[PATCH v1 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[PATCH v1 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[Ian Rogers]

An intel-pt trace can be turned into LBR events either in perf script
or perf inject with the --itrace=L option. With perf inject the
generated perf.data file failed to be parsed as the sample events were
out of sync with their perf_event_attr. A range of fixes were
required.

This patch was separated from a large perf script refactor that
highlighted the breakage:
https://lore.kernel.org/lkml/20260425224951.174663-1-irogers@google.com/

Ian Rogers (2):
  perf event: Fix size of synthesized sample with branch stacks
  perf inject: Fix itrace branch stack synthesis

 tools/perf/bench/inject-buildid.c  |  9 ++--
 tools/perf/builtin-inject.c        | 83 ++++++++++++++++++++++++++++--
 tools/perf/tests/dlfilter-test.c   |  8 ++-
 tools/perf/tests/sample-parsing.c  |  5 +-
 tools/perf/util/arm-spe.c          |  7 ++-
 tools/perf/util/cs-etm.c           |  6 ++-
 tools/perf/util/intel-bts.c        |  3 +-
 tools/perf/util/intel-pt.c         | 13 +++--
 tools/perf/util/synthetic-events.c | 25 ++++++---
 tools/perf/util/synthetic-events.h |  6 ++-
 10 files changed, 135 insertions(+), 30 deletions(-)

-- 
2.54.0.545.g6539524ca2-goog

[PATCH v1 1/2] perf event: Fix size of synthesized sample with branch stacks

[Ian Rogers]

Synthesizing branch stacks for Intel-PT highlighed an issue where
PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the
perf_event_attr branch_sample_type. This caused an incorrect size
calculation.

Fix the writing of the nr and hw_idx values during sample event
synthesis.

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/bench/inject-buildid.c  |  9 ++++++---
 tools/perf/builtin-inject.c        | 12 +++++++++---
 tools/perf/tests/dlfilter-test.c   |  8 ++++++--
 tools/perf/tests/sample-parsing.c  |  5 +++--
 tools/perf/util/arm-spe.c          |  7 +++++--
 tools/perf/util/cs-etm.c           |  6 ++++--
 tools/perf/util/intel-bts.c        |  3 ++-
 tools/perf/util/intel-pt.c         |  7 +++++--
 tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++-------
 tools/perf/util/synthetic-events.h |  6 ++++--
 10 files changed, 62 insertions(+), 26 deletions(-)

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7f..bfd2c5ec9488 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso,
 
 	event.header.type = PERF_RECORD_SAMPLE;
 	event.header.misc = PERF_RECORD_MISC_USER;
-	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
-
-	perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
+	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	perf_event__synthesize_sample(&event, bench_sample_type,
+				      /*read_format=*/0,
+				      /*branch_sample_type=*/0, &sample);
 
 	return writen(data->input_pipe[1], &event, event.header.size);
 }
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index f174bc69cec4..0c51cb4250d1 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -463,8 +463,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	perf_event__synthesize_sample(event_copy, sample_type,
-				      evsel->core.attr.read_format, sample);
+	ret = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+					    evsel->core.attr.read_format,
+					    evsel->core.attr.branch_sample_type, sample);
+	if (ret) {
+		pr_err("Failed to synthesize sample\n");
+		return ret;
+	}
 	return perf_event__repipe_synth(tool, event_copy);
 }
 
@@ -1100,7 +1105,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
 	sample_sw.period = sample->period;
 	sample_sw.time	 = sample->time;
 	perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
-				      evsel->core.attr.read_format, &sample_sw);
+				      evsel->core.attr.read_format,
+				      evsel->core.attr.branch_sample_type, &sample_sw);
 	build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
 	ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
 	perf_sample__exit(&sample_sw);
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index e63790c61d53..204663571943 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid
 
 	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.misc = PERF_RECORD_MISC_USER;
-	event->header.size = perf_event__sample_event_size(&sample, sample_type, 0);
-	err = perf_event__synthesize_sample(event, sample_type, 0, &sample);
+	event->header.size = perf_event__sample_event_size(&sample, sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	err = perf_event__synthesize_sample(event, sample_type,
+					    /*read_format=*/0,
+					    /*branch_sample_type=*/0, &sample);
 	if (err)
 		return test_result("perf_event__synthesize_sample() failed", TEST_FAIL);
 
diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
index a7327c942ca2..55f0b73ca20e 100644
--- a/tools/perf/tests/sample-parsing.c
+++ b/tools/perf/tests/sample-parsing.c
@@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 		sample.read.one.lost  = 1;
 	}
 
-	sz = perf_event__sample_event_size(&sample, sample_type, read_format);
+	sz = perf_event__sample_event_size(&sample, sample_type, read_format,
+					   evsel.core.attr.branch_sample_type);
 	bufsz = sz + 4096; /* Add a bit for overrun checking */
 	event = malloc(bufsz);
 	if (!event) {
@@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 	event->header.size = sz;
 
 	err = perf_event__synthesize_sample(event, sample_type, read_format,
-					    &sample);
+					    evsel.core.attr.branch_sample_type, &sample);
 	if (err) {
 		pr_debug("%s failed for sample_type %#"PRIx64", error %d\n",
 			 "perf_event__synthesize_sample", sample_type, err);
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index e5835042acdf..c4ed9f10e731 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -484,8 +484,11 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
 
 static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	event->header.type = PERF_RECORD_SAMPLE;
+	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     /*branch_sample_type=*/0, sample);
 }
 
 static inline int
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 8a639d2e51a4..1ebc1a6a5e75 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1425,8 +1425,10 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
 static int cs_etm__inject_event(union perf_event *event,
 			       struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     /*branch_sample_type=*/0, sample);
 }
 
 
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index 382255393fb3..0b18ebd13f7c 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq,
 		event.sample.header.size = bts->branches_event_size;
 		ret = perf_event__synthesize_sample(&event,
 						    bts->branches_sample_type,
-						    0, &sample);
+						    /*read_format=*/0, /*branch_sample_type=*/0,
+						    &sample);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index fc9eec8b54b8..5142983e3243 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1731,8 +1731,11 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 static int intel_pt_inject_event(union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     /*branch_sample_type=*/0, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 85bee747f4cd..2461f25a4d7d 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool,
 	return process(tool, (union perf_event *) &event, NULL, machine);
 }
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format)
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format,
+				     u64 branch_sample_type)
 {
 	size_t sz, result = sizeof(struct perf_record_sample);
 
@@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
+		/* nr */
+		sz += sizeof(u64);
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)
+			sz += sizeof(u64);
 		result += sz;
 	}
 
@@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format,
 }
 
 int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
-				  const struct perf_sample *sample)
+				  u64 branch_sample_type, const struct perf_sample *sample)
 {
 	__u64 *array;
 	size_t sz;
@@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
-		memcpy(array, sample->branch_stack, sz);
+
+		*array++ = sample->branch_stack->nr;
+
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) {
+			if (sample->no_hw_idx)
+				*array++ = 0;
+			else
+				*array++ = sample->branch_stack->hw_idx;
+		}
+
+		memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz);
 		array = (void *)array + sz;
 	}
 
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index b0edad0c3100..8c7f49f9ccf5 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_
 int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
+int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
+				  u64 branch_sample_type, const struct perf_sample *sample);
 int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
 int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
@@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session,
 
 int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
+				     u64 read_format, u64 branch_sample_type);
 
 int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
-- 
2.54.0.545.g6539524ca2-goog

Re: [PATCH v1 1/2] perf event: Fix size of synthesized sample with branch stacks

[Namhyung Kim]

On Tue, Apr 28, 2026 at 12:03:27AM -0700, Ian Rogers wrote:
> Synthesizing branch stacks for Intel-PT highlighed an issue where
> PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the
> perf_event_attr branch_sample_type. This caused an incorrect size
> calculation.
> 
> Fix the writing of the nr and hw_idx values during sample event
> synthesis.
> 
> Assisted-by: Gemini:gemini-3.1-pro-preview
> Signed-off-by: Ian Rogers <irogers@google.com>

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung

> ---
>  tools/perf/bench/inject-buildid.c  |  9 ++++++---
>  tools/perf/builtin-inject.c        | 12 +++++++++---
>  tools/perf/tests/dlfilter-test.c   |  8 ++++++--
>  tools/perf/tests/sample-parsing.c  |  5 +++--
>  tools/perf/util/arm-spe.c          |  7 +++++--
>  tools/perf/util/cs-etm.c           |  6 ++++--
>  tools/perf/util/intel-bts.c        |  3 ++-
>  tools/perf/util/intel-pt.c         |  7 +++++--
>  tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++-------
>  tools/perf/util/synthetic-events.h |  6 ++++--
>  10 files changed, 62 insertions(+), 26 deletions(-)
> 
> diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
> index aad572a78d7f..bfd2c5ec9488 100644
> --- a/tools/perf/bench/inject-buildid.c
> +++ b/tools/perf/bench/inject-buildid.c
> @@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso,
>  
>  	event.header.type = PERF_RECORD_SAMPLE;
>  	event.header.misc = PERF_RECORD_MISC_USER;
> -	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
> -
> -	perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
> +	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type,
> +							   /*read_format=*/0,
> +							   /*branch_sample_type=*/0);
> +	perf_event__synthesize_sample(&event, bench_sample_type,
> +				      /*read_format=*/0,
> +				      /*branch_sample_type=*/0, &sample);
>  
>  	return writen(data->input_pipe[1], &event, event.header.size);
>  }
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index f174bc69cec4..0c51cb4250d1 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -463,8 +463,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
>  	/* remove sample_type {STACK,REGS}_USER for synthesize */
>  	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
>  
> -	perf_event__synthesize_sample(event_copy, sample_type,
> -				      evsel->core.attr.read_format, sample);
> +	ret = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
> +					    evsel->core.attr.read_format,
> +					    evsel->core.attr.branch_sample_type, sample);
> +	if (ret) {
> +		pr_err("Failed to synthesize sample\n");
> +		return ret;
> +	}
>  	return perf_event__repipe_synth(tool, event_copy);
>  }
>  
> @@ -1100,7 +1105,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
>  	sample_sw.period = sample->period;
>  	sample_sw.time	 = sample->time;
>  	perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
> -				      evsel->core.attr.read_format, &sample_sw);
> +				      evsel->core.attr.read_format,
> +				      evsel->core.attr.branch_sample_type, &sample_sw);
>  	build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
>  	ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
>  	perf_sample__exit(&sample_sw);
> diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
> index e63790c61d53..204663571943 100644
> --- a/tools/perf/tests/dlfilter-test.c
> +++ b/tools/perf/tests/dlfilter-test.c
> @@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid
>  
>  	event->header.type = PERF_RECORD_SAMPLE;
>  	event->header.misc = PERF_RECORD_MISC_USER;
> -	event->header.size = perf_event__sample_event_size(&sample, sample_type, 0);
> -	err = perf_event__synthesize_sample(event, sample_type, 0, &sample);
> +	event->header.size = perf_event__sample_event_size(&sample, sample_type,
> +							   /*read_format=*/0,
> +							   /*branch_sample_type=*/0);
> +	err = perf_event__synthesize_sample(event, sample_type,
> +					    /*read_format=*/0,
> +					    /*branch_sample_type=*/0, &sample);
>  	if (err)
>  		return test_result("perf_event__synthesize_sample() failed", TEST_FAIL);
>  
> diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
> index a7327c942ca2..55f0b73ca20e 100644
> --- a/tools/perf/tests/sample-parsing.c
> +++ b/tools/perf/tests/sample-parsing.c
> @@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
>  		sample.read.one.lost  = 1;
>  	}
>  
> -	sz = perf_event__sample_event_size(&sample, sample_type, read_format);
> +	sz = perf_event__sample_event_size(&sample, sample_type, read_format,
> +					   evsel.core.attr.branch_sample_type);
>  	bufsz = sz + 4096; /* Add a bit for overrun checking */
>  	event = malloc(bufsz);
>  	if (!event) {
> @@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
>  	event->header.size = sz;
>  
>  	err = perf_event__synthesize_sample(event, sample_type, read_format,
> -					    &sample);
> +					    evsel.core.attr.branch_sample_type, &sample);
>  	if (err) {
>  		pr_debug("%s failed for sample_type %#"PRIx64", error %d\n",
>  			 "perf_event__synthesize_sample", sample_type, err);
> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> index e5835042acdf..c4ed9f10e731 100644
> --- a/tools/perf/util/arm-spe.c
> +++ b/tools/perf/util/arm-spe.c
> @@ -484,8 +484,11 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
>  
>  static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
>  {
> -	event->header.size = perf_event__sample_event_size(sample, type, 0);
> -	return perf_event__synthesize_sample(event, type, 0, sample);
> +	event->header.type = PERF_RECORD_SAMPLE;
> +	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
> +							   /*branch_sample_type=*/0);
> +	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
> +					     /*branch_sample_type=*/0, sample);
>  }
>  
>  static inline int
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index 8a639d2e51a4..1ebc1a6a5e75 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -1425,8 +1425,10 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
>  static int cs_etm__inject_event(union perf_event *event,
>  			       struct perf_sample *sample, u64 type)
>  {
> -	event->header.size = perf_event__sample_event_size(sample, type, 0);
> -	return perf_event__synthesize_sample(event, type, 0, sample);
> +	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
> +							   /*branch_sample_type=*/0);
> +	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
> +					     /*branch_sample_type=*/0, sample);
>  }
>  
>  
> diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
> index 382255393fb3..0b18ebd13f7c 100644
> --- a/tools/perf/util/intel-bts.c
> +++ b/tools/perf/util/intel-bts.c
> @@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq,
>  		event.sample.header.size = bts->branches_event_size;
>  		ret = perf_event__synthesize_sample(&event,
>  						    bts->branches_sample_type,
> -						    0, &sample);
> +						    /*read_format=*/0, /*branch_sample_type=*/0,
> +						    &sample);
>  		if (ret)
>  			return ret;
>  	}
> diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> index fc9eec8b54b8..5142983e3243 100644
> --- a/tools/perf/util/intel-pt.c
> +++ b/tools/perf/util/intel-pt.c
> @@ -1731,8 +1731,11 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
>  static int intel_pt_inject_event(union perf_event *event,
>  				 struct perf_sample *sample, u64 type)
>  {
> -	event->header.size = perf_event__sample_event_size(sample, type, 0);
> -	return perf_event__synthesize_sample(event, type, 0, sample);
> +	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
> +							   /*branch_sample_type=*/0);
> +
> +	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
> +					     /*branch_sample_type=*/0, sample);
>  }
>  
>  static inline int intel_pt_opt_inject(struct intel_pt *pt,
> diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> index 85bee747f4cd..2461f25a4d7d 100644
> --- a/tools/perf/util/synthetic-events.c
> +++ b/tools/perf/util/synthetic-events.c
> @@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool,
>  	return process(tool, (union perf_event *) &event, NULL, machine);
>  }
>  
> -size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format)
> +size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format,
> +				     u64 branch_sample_type)
>  {
>  	size_t sz, result = sizeof(struct perf_record_sample);
>  
> @@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
>  
>  	if (type & PERF_SAMPLE_BRANCH_STACK) {
>  		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
> -		/* nr, hw_idx */
> -		sz += 2 * sizeof(u64);
> +		/* nr */
> +		sz += sizeof(u64);
> +		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)
> +			sz += sizeof(u64);
>  		result += sz;
>  	}
>  
> @@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format,
>  }
>  
>  int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
> -				  const struct perf_sample *sample)
> +				  u64 branch_sample_type, const struct perf_sample *sample)
>  {
>  	__u64 *array;
>  	size_t sz;
> @@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
>  
>  	if (type & PERF_SAMPLE_BRANCH_STACK) {
>  		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
> -		/* nr, hw_idx */
> -		sz += 2 * sizeof(u64);
> -		memcpy(array, sample->branch_stack, sz);
> +
> +		*array++ = sample->branch_stack->nr;
> +
> +		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) {
> +			if (sample->no_hw_idx)
> +				*array++ = 0;
> +			else
> +				*array++ = sample->branch_stack->hw_idx;
> +		}
> +
> +		memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz);
>  		array = (void *)array + sz;
>  	}
>  
> diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
> index b0edad0c3100..8c7f49f9ccf5 100644
> --- a/tools/perf/util/synthetic-events.h
> +++ b/tools/perf/util/synthetic-events.h
> @@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_
>  int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
>  int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
>  int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
> -int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
> +int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
> +				  u64 branch_sample_type, const struct perf_sample *sample);
>  int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
>  int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
>  int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
> @@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session,
>  
>  int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
>  
> -size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
> +size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
> +				     u64 read_format, u64 branch_sample_type);
>  
>  int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
>  				  struct target *target, struct perf_thread_map *threads,
> -- 
> 2.54.0.545.g6539524ca2-goog
> 

[PATCH v1 2/2] perf inject: Fix itrace branch stack synthesis

[Ian Rogers]

When using "perf inject --itrace=L" to synthesize branch stacks from
AUX data, several issues caused failures with the generated file:

1. The synthesized samples were delivered without the
   PERF_SAMPLE_BRANCH_STACK flag if it was not in the original event's
   sample_type. Fixed by using sample_type | evsel->synth_sample_type
   in intel_pt_deliver_synth_event.

2. The record layout was misaligned because of inconsistent handling
   of PERF_SAMPLE_BRANCH_HW_INDEX. Fixed by explicitly writing nr and
   hw_idx in perf_event__synthesize_sample.

3. Modifying evsel->core.attr.sample_type early in __cmd_inject caused
   parse failures for subsequent records in the input file. Fixed by
   moving this modification to just before writing the header.

4. perf_event__repipe_sample was narrowed to only synthesize samples
   when branch stack injection was requested, and restored the use of
   perf_inject__cut_auxtrace_sample as a fallback to preserve
   functionality.

5. Potential Heap Overflow in perf_event__repipe_sample : Addressed by
   adding a check that prints an error and returns -EFAULT if the
   calculated event size exceeds PERF_SAMPLE_MAX_SIZE , as you
   requested.

6. Header vs Payload Mismatch in __cmd_inject : Addressed by narrowing
   the condition so that HEADER_BRANCH_STACK is only set in the file
   header if add_last_branch was true.

7. NULL Pointer Dereference in intel-pt.c : Addressed by updating the
   condition in intel_pt_do_synth_pebs_sample to fill sample.
   branch_stack if it was synthesized, even if not in the original
   sample_type .

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-inject.c | 87 ++++++++++++++++++++++++++++++++-----
 tools/perf/util/intel-pt.c  |  6 ++-
 2 files changed, 81 insertions(+), 12 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 0c51cb4250d1..1f4d25a0efba 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -223,6 +223,11 @@ static int perf_event__repipe_attr(const struct perf_tool *tool,
 						  tool);
 	int ret;
 
+	if (inject->itrace_synth_opts.add_last_branch) {
+		event->attr.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+		event->attr.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+	}
+
 	ret = perf_event__process_attr(tool, event, pevlist);
 	if (ret)
 		return ret;
@@ -375,7 +380,60 @@ static int perf_event__repipe_sample(const struct perf_tool *tool,
 
 	build_id__mark_dso_hit(tool, event, sample, evsel, machine);
 
-	if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
+	if (inject->itrace_synth_opts.set &&
+	    (inject->itrace_synth_opts.last_branch ||
+	     inject->itrace_synth_opts.add_last_branch)) {
+		union perf_event *event_copy = (void *)inject->event_copy;
+		struct branch_stack dummy_bs = { .nr = 0, .hw_idx = 0 };
+		int err;
+		size_t sz;
+		u64 orig_type = evsel->core.attr.sample_type;
+		u64 orig_branch_type = evsel->core.attr.branch_sample_type;
+
+		if (event_copy == NULL) {
+			inject->event_copy = malloc(PERF_SAMPLE_MAX_SIZE);
+			if (!inject->event_copy)
+				return -ENOMEM;
+
+			event_copy = (void *)inject->event_copy;
+		}
+
+		if (!sample->branch_stack)
+			sample->branch_stack = &dummy_bs;
+
+		if (inject->itrace_synth_opts.add_last_branch) {
+			/* Temporarily add in type bits for synthesis. */
+			evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+			evsel->core.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+		}
+		evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+		sz = perf_event__sample_event_size(sample, evsel->core.attr.sample_type,
+						   evsel->core.attr.read_format,
+						   evsel->core.attr.branch_sample_type);
+
+		if (sz > PERF_SAMPLE_MAX_SIZE) {
+			pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+			return -EFAULT;
+		}
+
+		event_copy->header.type = PERF_RECORD_SAMPLE;
+		event_copy->header.misc = event->header.misc;
+		event_copy->header.size = sz;
+
+		err = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+						    evsel->core.attr.read_format,
+						    evsel->core.attr.branch_sample_type, sample);
+
+		evsel->core.attr.sample_type = orig_type;
+		evsel->core.attr.branch_sample_type = orig_branch_type;
+
+		if (err) {
+			pr_err("Failed to synthesize sample\n");
+			return err;
+		}
+		event = event_copy;
+	} else if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
 		event = perf_inject__cut_auxtrace_sample(inject, event, sample);
 		if (IS_ERR(event))
 			return PTR_ERR(event);
@@ -463,13 +521,9 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	ret = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
-					    evsel->core.attr.read_format,
-					    evsel->core.attr.branch_sample_type, sample);
-	if (ret) {
-		pr_err("Failed to synthesize sample\n");
-		return ret;
-	}
+	perf_event__synthesize_sample(event_copy, sample_type,
+				      evsel->core.attr.read_format,
+				      evsel->core.attr.branch_sample_type, sample);
 	return perf_event__repipe_synth(tool, event_copy);
 }
 
@@ -2440,12 +2494,25 @@ static int __cmd_inject(struct perf_inject *inject)
 		 * synthesized hardware events, so clear the feature flag.
 		 */
 		if (inject->itrace_synth_opts.set) {
+			struct evsel *evsel;
+
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
-			if (inject->itrace_synth_opts.last_branch ||
-			    inject->itrace_synth_opts.add_last_branch)
+
+			evlist__for_each_entry(session->evlist, evsel) {
+				evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+			}
+
+			if (inject->itrace_synth_opts.add_last_branch) {
 				perf_header__set_feat(&session->header,
 						      HEADER_BRANCH_STACK);
+
+				evlist__for_each_entry(session->evlist, evsel) {
+					evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+					evsel->core.attr.branch_sample_type |=
+						PERF_SAMPLE_BRANCH_HW_INDEX;
+				}
+			}
 		}
 
 		/*
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 5142983e3243..2dce6106c038 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1731,6 +1731,7 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 static int intel_pt_inject_event(union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
+	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
 							   /*branch_sample_type=*/0);
 
@@ -2489,7 +2490,7 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		intel_pt_add_xmm(intr_regs, pos, items, regs_mask);
 	}
 
-	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+	if ((sample_type | evsel->synth_sample_type) & PERF_SAMPLE_BRANCH_STACK) {
 		if (items->mask[INTEL_PT_LBR_0_POS] ||
 		    items->mask[INTEL_PT_LBR_1_POS] ||
 		    items->mask[INTEL_PT_LBR_2_POS]) {
@@ -2560,7 +2561,8 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		sample.transaction = txn;
 	}
 
-	ret = intel_pt_deliver_synth_event(pt, event, &sample, sample_type);
+	ret = intel_pt_deliver_synth_event(pt, event, &sample,
+					   sample_type | evsel->synth_sample_type);
 	perf_sample__exit(&sample);
 	return ret;
 }
-- 
2.54.0.545.g6539524ca2-goog

[PATCH v2 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[Ian Rogers]

An intel-pt trace can be turned into LBR events either in perf script
or perf inject with the --itrace=L option. With perf inject the
generated perf.data file failed to be parsed as the sample events were
out of sync with their perf_event_attr. A range of fixes were
required.

This patch was separated from a large perf script refactor that
highlighted the breakage:
https://lore.kernel.org/lkml/20260425224951.174663-1-irogers@google.com/

v2: Response to sashiko fixes for patch 2, Namhyung's acked-by for patch 1.

v1: https://lore.kernel.org/lkml/20260428070328.1880314-1-irogers@google.com/

Ian Rogers (2):
  perf event: Fix size of synthesized sample with branch stacks
  perf inject: Fix itrace branch stack synthesis

 tools/perf/bench/inject-buildid.c  |   9 ++-
 tools/perf/builtin-inject.c        | 107 ++++++++++++++++++++++++++---
 tools/perf/tests/dlfilter-test.c   |   8 ++-
 tools/perf/tests/sample-parsing.c  |   5 +-
 tools/perf/util/arm-spe.c          |   7 +-
 tools/perf/util/cs-etm.c           |   6 +-
 tools/perf/util/intel-bts.c        |   3 +-
 tools/perf/util/intel-pt.c         |  26 +++++--
 tools/perf/util/synthetic-events.c |  25 +++++--
 tools/perf/util/synthetic-events.h |   6 +-
 10 files changed, 165 insertions(+), 37 deletions(-)

-- 
2.54.0.545.g6539524ca2-goog

[PATCH v2 1/2] perf event: Fix size of synthesized sample with branch stacks

[Ian Rogers]

Synthesizing branch stacks for Intel-PT highlighed an issue where
PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the
perf_event_attr branch_sample_type. This caused an incorrect size
calculation.

Fix the writing of the nr and hw_idx values during sample event
synthesis.

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/bench/inject-buildid.c  |  9 ++++++---
 tools/perf/builtin-inject.c        | 12 +++++++++---
 tools/perf/tests/dlfilter-test.c   |  8 ++++++--
 tools/perf/tests/sample-parsing.c  |  5 +++--
 tools/perf/util/arm-spe.c          |  7 +++++--
 tools/perf/util/cs-etm.c           |  6 ++++--
 tools/perf/util/intel-bts.c        |  3 ++-
 tools/perf/util/intel-pt.c         |  7 +++++--
 tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++-------
 tools/perf/util/synthetic-events.h |  6 ++++--
 10 files changed, 62 insertions(+), 26 deletions(-)

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7f..bfd2c5ec9488 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso,
 
 	event.header.type = PERF_RECORD_SAMPLE;
 	event.header.misc = PERF_RECORD_MISC_USER;
-	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
-
-	perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
+	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	perf_event__synthesize_sample(&event, bench_sample_type,
+				      /*read_format=*/0,
+				      /*branch_sample_type=*/0, &sample);
 
 	return writen(data->input_pipe[1], &event, event.header.size);
 }
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index f174bc69cec4..0c51cb4250d1 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -463,8 +463,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	perf_event__synthesize_sample(event_copy, sample_type,
-				      evsel->core.attr.read_format, sample);
+	ret = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+					    evsel->core.attr.read_format,
+					    evsel->core.attr.branch_sample_type, sample);
+	if (ret) {
+		pr_err("Failed to synthesize sample\n");
+		return ret;
+	}
 	return perf_event__repipe_synth(tool, event_copy);
 }
 
@@ -1100,7 +1105,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
 	sample_sw.period = sample->period;
 	sample_sw.time	 = sample->time;
 	perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
-				      evsel->core.attr.read_format, &sample_sw);
+				      evsel->core.attr.read_format,
+				      evsel->core.attr.branch_sample_type, &sample_sw);
 	build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
 	ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
 	perf_sample__exit(&sample_sw);
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index e63790c61d53..204663571943 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid
 
 	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.misc = PERF_RECORD_MISC_USER;
-	event->header.size = perf_event__sample_event_size(&sample, sample_type, 0);
-	err = perf_event__synthesize_sample(event, sample_type, 0, &sample);
+	event->header.size = perf_event__sample_event_size(&sample, sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	err = perf_event__synthesize_sample(event, sample_type,
+					    /*read_format=*/0,
+					    /*branch_sample_type=*/0, &sample);
 	if (err)
 		return test_result("perf_event__synthesize_sample() failed", TEST_FAIL);
 
diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
index a7327c942ca2..55f0b73ca20e 100644
--- a/tools/perf/tests/sample-parsing.c
+++ b/tools/perf/tests/sample-parsing.c
@@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 		sample.read.one.lost  = 1;
 	}
 
-	sz = perf_event__sample_event_size(&sample, sample_type, read_format);
+	sz = perf_event__sample_event_size(&sample, sample_type, read_format,
+					   evsel.core.attr.branch_sample_type);
 	bufsz = sz + 4096; /* Add a bit for overrun checking */
 	event = malloc(bufsz);
 	if (!event) {
@@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 	event->header.size = sz;
 
 	err = perf_event__synthesize_sample(event, sample_type, read_format,
-					    &sample);
+					    evsel.core.attr.branch_sample_type, &sample);
 	if (err) {
 		pr_debug("%s failed for sample_type %#"PRIx64", error %d\n",
 			 "perf_event__synthesize_sample", sample_type, err);
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index e5835042acdf..c4ed9f10e731 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -484,8 +484,11 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
 
 static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	event->header.type = PERF_RECORD_SAMPLE;
+	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     /*branch_sample_type=*/0, sample);
 }
 
 static inline int
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 8a639d2e51a4..1ebc1a6a5e75 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1425,8 +1425,10 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
 static int cs_etm__inject_event(union perf_event *event,
 			       struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     /*branch_sample_type=*/0, sample);
 }
 
 
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index 382255393fb3..0b18ebd13f7c 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq,
 		event.sample.header.size = bts->branches_event_size;
 		ret = perf_event__synthesize_sample(&event,
 						    bts->branches_sample_type,
-						    0, &sample);
+						    /*read_format=*/0, /*branch_sample_type=*/0,
+						    &sample);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index fc9eec8b54b8..5142983e3243 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1731,8 +1731,11 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 static int intel_pt_inject_event(union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     /*branch_sample_type=*/0, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 85bee747f4cd..2461f25a4d7d 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool,
 	return process(tool, (union perf_event *) &event, NULL, machine);
 }
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format)
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format,
+				     u64 branch_sample_type)
 {
 	size_t sz, result = sizeof(struct perf_record_sample);
 
@@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
+		/* nr */
+		sz += sizeof(u64);
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)
+			sz += sizeof(u64);
 		result += sz;
 	}
 
@@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format,
 }
 
 int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
-				  const struct perf_sample *sample)
+				  u64 branch_sample_type, const struct perf_sample *sample)
 {
 	__u64 *array;
 	size_t sz;
@@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
-		memcpy(array, sample->branch_stack, sz);
+
+		*array++ = sample->branch_stack->nr;
+
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) {
+			if (sample->no_hw_idx)
+				*array++ = 0;
+			else
+				*array++ = sample->branch_stack->hw_idx;
+		}
+
+		memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz);
 		array = (void *)array + sz;
 	}
 
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index b0edad0c3100..8c7f49f9ccf5 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_
 int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
+int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
+				  u64 branch_sample_type, const struct perf_sample *sample);
 int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
 int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
@@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session,
 
 int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
+				     u64 read_format, u64 branch_sample_type);
 
 int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
-- 
2.54.0.545.g6539524ca2-goog

[PATCH v2 2/2] perf inject: Fix itrace branch stack synthesis

[Ian Rogers]

When using "perf inject --itrace=L" to synthesize branch stacks from
AUX data, several issues caused failures with the generated file:

1. The synthesized samples were delivered without the
   PERF_SAMPLE_BRANCH_STACK flag if it was not in the original event's
   sample_type. Fixed by using sample_type | evsel->synth_sample_type
   in intel_pt_do_synth_pebs_sample.

2. Modifying evsel->core.attr.sample_type early in __cmd_inject caused
   parse failures for subsequent records in the input file. Fixed by
   moving this modification to just before writing the header.

3. perf_event__repipe_sample was narrowed to only synthesize samples
   when branch stack injection was requested, and restored the use of
   perf_inject__cut_auxtrace_sample as a fallback to preserve
   functionality.

4. Potential Heap Overflow in perf_event__repipe_sample: Addressed by
   adding a check that prints an error and returns -EFAULT if the
   calculated event size exceeds PERF_SAMPLE_MAX_SIZE.

5. Header vs Payload Mismatch in __cmd_inject: Addressed by narrowing
   the condition so that HEADER_BRANCH_STACK is only set in the file
   header if add_last_branch was true.

6. NULL Pointer Dereference in intel-pt.c: Addressed by updating the
   condition in intel_pt_do_synth_pebs_sample to fill sample.
   branch_stack if it was synthesized, even if not in the original
   sample_type.

7. Modifying event attributes in perf_event__repipe_attr early caused
   downstream parser breakage in pipe mode. Fixed by clearing
   PERF_SAMPLE_AUX when itrace_synth_opts.set is true to ensure the
   headers match the stripped payload. Also added a size check against
   struct perf_record_header_attr to prevent out-of-bounds writes.

8. Potential dangling pointer vulnerability in perf_event__repipe_sample:
   Addressed by restoring the original sample->branch_stack pointer
   before returning.

9. Off-by-one error in sample size check in perf_event__repipe_sample:
   Fixed by checking if sz >= PERF_SAMPLE_MAX_SIZE instead of >.

10. Unadvertised size field left in payload by cut_auxtrace_sample:
    Addressed by excluding the 8-byte size field from the copied
    payload to correctly match the cleared PERF_SAMPLE_AUX bit.

11. Silent data corruption in convert_sample_callchain: Addressed by
    restoring the error check for perf_event__synthesize_sample to
    prevent writing malformed or uninitialized memory.

12. Omission of hw_idx in PEBS synthesis: Fixed by passing the correct
    evsel->core.attr.branch_sample_type instead of 0 in intel-pt.c.

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
v2:
- Fix error handling in callchain conversion by keeping the error check.
- Fix header advertise issues in pipe mode by clearing PERF_SAMPLE_AUX.
- Prevent out-of-bounds writes in attribute repiping with size checks.
- Fix sample payload misalignment by cutting the unadvertised AUX size field.
- Fix off-by-one check in sample size overflow to correctly use >=.
- Avoid dangling pointer vulnerability by restoring the branch_stack pointer.
- Pass evsel's branch_sample_type to synthesized samples to prevent hw_idx omission.
---
 tools/perf/builtin-inject.c | 97 ++++++++++++++++++++++++++++++++++---
 tools/perf/util/intel-pt.c  | 23 ++++++---
 2 files changed, 106 insertions(+), 14 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 0c51cb4250d1..13fb1f05ceb2 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -223,6 +223,19 @@ static int perf_event__repipe_attr(const struct perf_tool *tool,
 						  tool);
 	int ret;
 
+	if (event->header.size < sizeof(struct perf_record_header_attr)) {
+		pr_err("Attribute event size %u is too small\n", event->header.size);
+		return -EINVAL;
+	}
+
+	if (inject->itrace_synth_opts.set)
+		event->attr.attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+	if (inject->itrace_synth_opts.add_last_branch) {
+		event->attr.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+		event->attr.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+	}
+
 	ret = perf_event__process_attr(tool, event, pevlist);
 	if (ret)
 		return ret;
@@ -330,8 +343,8 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 				 union perf_event *event,
 				 struct perf_sample *sample)
 {
-	size_t sz1 = sample->aux_sample.data - (void *)event;
-	size_t sz2 = event->header.size - sample->aux_sample.size - sz1;
+	size_t sz1 = sample->aux_sample.data - (void *)event - sizeof(u64);
+	size_t sz2 = event->header.size - sample->aux_sample.size - (sz1 + sizeof(u64));
 	union perf_event *ev;
 
 	if (inject->event_copy == NULL) {
@@ -342,13 +355,12 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 	ev = (union perf_event *)inject->event_copy;
 	if (sz1 > event->header.size || sz2 > event->header.size ||
 	    sz1 + sz2 > event->header.size ||
-	    sz1 < sizeof(struct perf_event_header) + sizeof(u64))
+	    sz1 < sizeof(struct perf_event_header))
 		return event;
 
 	memcpy(ev, event, sz1);
 	memcpy((void *)ev + sz1, (void *)event + event->header.size - sz2, sz2);
 	ev->header.size = sz1 + sz2;
-	((u64 *)((void *)ev + sz1))[-1] = 0;
 
 	return ev;
 }
@@ -375,7 +387,63 @@ static int perf_event__repipe_sample(const struct perf_tool *tool,
 
 	build_id__mark_dso_hit(tool, event, sample, evsel, machine);
 
-	if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
+	if (inject->itrace_synth_opts.set &&
+	    (inject->itrace_synth_opts.last_branch ||
+	     inject->itrace_synth_opts.add_last_branch)) {
+		union perf_event *event_copy = (void *)inject->event_copy;
+		struct branch_stack dummy_bs = { .nr = 0, .hw_idx = 0 };
+		int err;
+		size_t sz;
+		u64 orig_type = evsel->core.attr.sample_type;
+		u64 orig_branch_type = evsel->core.attr.branch_sample_type;
+
+		struct branch_stack *orig_bs = sample->branch_stack;
+
+		if (event_copy == NULL) {
+			inject->event_copy = malloc(PERF_SAMPLE_MAX_SIZE);
+			if (!inject->event_copy)
+				return -ENOMEM;
+
+			event_copy = (void *)inject->event_copy;
+		}
+
+		if (!sample->branch_stack)
+			sample->branch_stack = &dummy_bs;
+
+		if (inject->itrace_synth_opts.add_last_branch) {
+			/* Temporarily add in type bits for synthesis. */
+			evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+			evsel->core.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+		}
+		evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+		sz = perf_event__sample_event_size(sample, evsel->core.attr.sample_type,
+						   evsel->core.attr.read_format,
+						   evsel->core.attr.branch_sample_type);
+
+		if (sz >= PERF_SAMPLE_MAX_SIZE) {
+			pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+			return -EFAULT;
+		}
+
+		event_copy->header.type = PERF_RECORD_SAMPLE;
+		event_copy->header.misc = event->header.misc;
+		event_copy->header.size = sz;
+
+		err = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+						    evsel->core.attr.read_format,
+						    evsel->core.attr.branch_sample_type, sample);
+
+		evsel->core.attr.sample_type = orig_type;
+		evsel->core.attr.branch_sample_type = orig_branch_type;
+		sample->branch_stack = orig_bs;
+
+		if (err) {
+			pr_err("Failed to synthesize sample\n");
+			return err;
+		}
+		event = event_copy;
+	} else if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
 		event = perf_inject__cut_auxtrace_sample(inject, event, sample);
 		if (IS_ERR(event))
 			return PTR_ERR(event);
@@ -463,7 +531,7 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	ret = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+	ret = perf_event__synthesize_sample(event_copy, sample_type,
 					    evsel->core.attr.read_format,
 					    evsel->core.attr.branch_sample_type, sample);
 	if (ret) {
@@ -2440,12 +2508,25 @@ static int __cmd_inject(struct perf_inject *inject)
 		 * synthesized hardware events, so clear the feature flag.
 		 */
 		if (inject->itrace_synth_opts.set) {
+			struct evsel *evsel;
+
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
-			if (inject->itrace_synth_opts.last_branch ||
-			    inject->itrace_synth_opts.add_last_branch)
+
+			evlist__for_each_entry(session->evlist, evsel) {
+				evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+			}
+
+			if (inject->itrace_synth_opts.add_last_branch) {
 				perf_header__set_feat(&session->header,
 						      HEADER_BRANCH_STACK);
+
+				evlist__for_each_entry(session->evlist, evsel) {
+					evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+					evsel->core.attr.branch_sample_type |=
+						PERF_SAMPLE_BRANCH_HW_INDEX;
+				}
+			}
 		}
 
 		/*
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 5142983e3243..f45dbdd4d323 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1728,14 +1728,24 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 	event->sample.header.misc = sample->cpumode;
 }
 
-static int intel_pt_inject_event(union perf_event *event,
+static int intel_pt_inject_event(struct intel_pt *pt, union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
+	struct evsel *evsel = NULL;
+	u64 branch_sample_type = 0;
+
+	if (pt->session && pt->session->evlist)
+		evsel = evlist__id2evsel(pt->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
-							   /*branch_sample_type=*/0);
+							   branch_sample_type);
 
 	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
-					     /*branch_sample_type=*/0, sample);
+					     branch_sample_type, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
@@ -1745,7 +1755,7 @@ static inline int intel_pt_opt_inject(struct intel_pt *pt,
 	if (!pt->synth_opts.inject)
 		return 0;
 
-	return intel_pt_inject_event(event, sample, type);
+	return intel_pt_inject_event(pt, event, sample, type);
 }
 
 static int intel_pt_deliver_synth_event(struct intel_pt *pt,
@@ -2489,7 +2499,7 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		intel_pt_add_xmm(intr_regs, pos, items, regs_mask);
 	}
 
-	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+	if ((sample_type | evsel->synth_sample_type) & PERF_SAMPLE_BRANCH_STACK) {
 		if (items->mask[INTEL_PT_LBR_0_POS] ||
 		    items->mask[INTEL_PT_LBR_1_POS] ||
 		    items->mask[INTEL_PT_LBR_2_POS]) {
@@ -2560,7 +2570,8 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		sample.transaction = txn;
 	}
 
-	ret = intel_pt_deliver_synth_event(pt, event, &sample, sample_type);
+	ret = intel_pt_deliver_synth_event(pt, event, &sample,
+					   sample_type | evsel->synth_sample_type);
 	perf_sample__exit(&sample);
 	return ret;
 }
-- 
2.54.0.545.g6539524ca2-goog

[PATCH v3 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[Ian Rogers]

An intel-pt trace can be turned into LBR events either in perf script
or perf inject with the --itrace=L option. With perf inject the
generated perf.data file failed to be parsed as the sample events were
out of sync with their perf_event_attr. A range of fixes were
required.

This patch was separated from a large perf script refactor that
highlighted the breakage:
https://lore.kernel.org/lkml/20260425224951.174663-1-irogers@google.com/

v3:
 - Add missing Fixes: tags on both commits.
 - Refactor perf_event__repipe_attr to avoid in-place modifications on
   read-only mmap buffers, preventing SIGSEGV in file mode and premature
   evsel updates in pipe mode.
 - Use perf_event__synthesize_attr to correctly construct and repipe
   attributes in pipe mode.
 - Replace manual arithmetic in convert_sample_callchain with
   perf_event__sample_event_size to prevent uninitialized memory leaks.
 - Retrieve evsel branch_sample_type dynamically in util/arm-spe.c and
   util/cs-etm.c instead of hardcoding 0, resolving missing hw_idx field
   on synthesized branch stacks.

v2: Response to sashiko fixes for patch 2, Namhyung's acked-by for patch 1.

v1: https://lore.kernel.org/lkml/20260428070328.1880314-1-irogers@google.com/

Ian Rogers (2):
  perf event: Fix size of synthesized sample with branch stacks
  perf inject: Fix itrace branch stack synthesis

 tools/perf/bench/inject-buildid.c  |   9 +-
 tools/perf/builtin-inject.c        | 141 +++++++++++++++++++++++++----
 tools/perf/tests/dlfilter-test.c   |   8 +-
 tools/perf/tests/sample-parsing.c  |   5 +-
 tools/perf/util/arm-spe.c          |  21 ++++-
 tools/perf/util/cs-etm.c           |  23 +++--
 tools/perf/util/intel-bts.c        |   3 +-
 tools/perf/util/intel-pt.c         |  26 ++++--
 tools/perf/util/synthetic-events.c |  25 +++--
 tools/perf/util/synthetic-events.h |   6 +-
 10 files changed, 216 insertions(+), 51 deletions(-)

-- 
2.54.0.563.g4f69b47b94-goog

[PATCH v3 1/2] perf event: Fix size of synthesized sample with branch stacks

[Ian Rogers]

Synthesizing branch stacks for Intel-PT highlighted an issue where
PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the
perf_event_attr branch_sample_type. This caused an incorrect size
calculation.

Fix the writing of the nr and hw_idx values during sample event
synthesis.

Fixes: d3f85437ad6a ("perf evsel: Support PERF_SAMPLE_BRANCH_HW_INDEX")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/bench/inject-buildid.c  |  9 ++++++---
 tools/perf/builtin-inject.c        | 12 +++++++++---
 tools/perf/tests/dlfilter-test.c   |  8 ++++++--
 tools/perf/tests/sample-parsing.c  |  5 +++--
 tools/perf/util/arm-spe.c          |  7 +++++--
 tools/perf/util/cs-etm.c           |  6 ++++--
 tools/perf/util/intel-bts.c        |  3 ++-
 tools/perf/util/intel-pt.c         |  7 +++++--
 tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++-------
 tools/perf/util/synthetic-events.h |  6 ++++--
 10 files changed, 62 insertions(+), 26 deletions(-)

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7f..bfd2c5ec9488 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso,
 
 	event.header.type = PERF_RECORD_SAMPLE;
 	event.header.misc = PERF_RECORD_MISC_USER;
-	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
-
-	perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
+	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	perf_event__synthesize_sample(&event, bench_sample_type,
+				      /*read_format=*/0,
+				      /*branch_sample_type=*/0, &sample);
 
 	return writen(data->input_pipe[1], &event, event.header.size);
 }
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index a2493f1097df..6bde3cc173b2 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -465,8 +465,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	perf_event__synthesize_sample(event_copy, sample_type,
-				      evsel->core.attr.read_format, sample);
+	ret = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+					    evsel->core.attr.read_format,
+					    evsel->core.attr.branch_sample_type, sample);
+	if (ret) {
+		pr_err("Failed to synthesize sample\n");
+		return ret;
+	}
 	return perf_event__repipe_synth(tool, event_copy);
 }
 
@@ -1102,7 +1107,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
 	sample_sw.period = sample->period;
 	sample_sw.time	 = sample->time;
 	perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
-				      evsel->core.attr.read_format, &sample_sw);
+				      evsel->core.attr.read_format,
+				      evsel->core.attr.branch_sample_type, &sample_sw);
 	build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
 	ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
 	perf_sample__exit(&sample_sw);
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index e63790c61d53..204663571943 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid
 
 	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.misc = PERF_RECORD_MISC_USER;
-	event->header.size = perf_event__sample_event_size(&sample, sample_type, 0);
-	err = perf_event__synthesize_sample(event, sample_type, 0, &sample);
+	event->header.size = perf_event__sample_event_size(&sample, sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	err = perf_event__synthesize_sample(event, sample_type,
+					    /*read_format=*/0,
+					    /*branch_sample_type=*/0, &sample);
 	if (err)
 		return test_result("perf_event__synthesize_sample() failed", TEST_FAIL);
 
diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
index a7327c942ca2..55f0b73ca20e 100644
--- a/tools/perf/tests/sample-parsing.c
+++ b/tools/perf/tests/sample-parsing.c
@@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 		sample.read.one.lost  = 1;
 	}
 
-	sz = perf_event__sample_event_size(&sample, sample_type, read_format);
+	sz = perf_event__sample_event_size(&sample, sample_type, read_format,
+					   evsel.core.attr.branch_sample_type);
 	bufsz = sz + 4096; /* Add a bit for overrun checking */
 	event = malloc(bufsz);
 	if (!event) {
@@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 	event->header.size = sz;
 
 	err = perf_event__synthesize_sample(event, sample_type, read_format,
-					    &sample);
+					    evsel.core.attr.branch_sample_type, &sample);
 	if (err) {
 		pr_debug("%s failed for sample_type %#"PRIx64", error %d\n",
 			 "perf_event__synthesize_sample", sample_type, err);
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 2b31da231ef3..24714f516856 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -489,8 +489,11 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
 
 static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	event->header.type = PERF_RECORD_SAMPLE;
+	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     /*branch_sample_type=*/0, sample);
 }
 
 static inline int
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 8a639d2e51a4..1ebc1a6a5e75 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1425,8 +1425,10 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
 static int cs_etm__inject_event(union perf_event *event,
 			       struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     /*branch_sample_type=*/0, sample);
 }
 
 
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index 382255393fb3..0b18ebd13f7c 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq,
 		event.sample.header.size = bts->branches_event_size;
 		ret = perf_event__synthesize_sample(&event,
 						    bts->branches_sample_type,
-						    0, &sample);
+						    /*read_format=*/0, /*branch_sample_type=*/0,
+						    &sample);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index fc9eec8b54b8..5142983e3243 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1731,8 +1731,11 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 static int intel_pt_inject_event(union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     /*branch_sample_type=*/0, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 85bee747f4cd..2461f25a4d7d 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool,
 	return process(tool, (union perf_event *) &event, NULL, machine);
 }
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format)
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format,
+				     u64 branch_sample_type)
 {
 	size_t sz, result = sizeof(struct perf_record_sample);
 
@@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
+		/* nr */
+		sz += sizeof(u64);
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)
+			sz += sizeof(u64);
 		result += sz;
 	}
 
@@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format,
 }
 
 int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
-				  const struct perf_sample *sample)
+				  u64 branch_sample_type, const struct perf_sample *sample)
 {
 	__u64 *array;
 	size_t sz;
@@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
-		memcpy(array, sample->branch_stack, sz);
+
+		*array++ = sample->branch_stack->nr;
+
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) {
+			if (sample->no_hw_idx)
+				*array++ = 0;
+			else
+				*array++ = sample->branch_stack->hw_idx;
+		}
+
+		memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz);
 		array = (void *)array + sz;
 	}
 
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index b0edad0c3100..8c7f49f9ccf5 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_
 int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
+int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
+				  u64 branch_sample_type, const struct perf_sample *sample);
 int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
 int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
@@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session,
 
 int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
+				     u64 read_format, u64 branch_sample_type);
 
 int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
-- 
2.54.0.563.g4f69b47b94-goog

[PATCH v3 2/2] perf inject: Fix itrace branch stack synthesis

[Ian Rogers]

When using "perf inject --itrace=L" to synthesize branch stacks from
AUX data, several issues caused failures with the generated file:

1. The synthesized samples were delivered without the
   PERF_SAMPLE_BRANCH_STACK flag if it was not in the original event's
   sample_type. Fixed by using sample_type | evsel->synth_sample_type
   in intel_pt_do_synth_pebs_sample.

2. Modifying evsel->core.attr.sample_type early in __cmd_inject caused
   parse failures for subsequent records in the input file. Fixed by
   moving this modification to just before writing the header.

3. perf_event__repipe_sample was narrowed to only synthesize samples
   when branch stack injection was requested, and restored the use of
   perf_inject__cut_auxtrace_sample as a fallback to preserve
   functionality.

4. Potential Heap Overflow in perf_event__repipe_sample: Addressed by
   adding a check that prints an error and returns -EFAULT if the
   calculated event size exceeds PERF_SAMPLE_MAX_SIZE.

5. Header vs Payload Mismatch in __cmd_inject: Addressed by narrowing
   the condition so that HEADER_BRANCH_STACK is only set in the file
   header if add_last_branch was true.

6. NULL Pointer Dereference in intel-pt.c: Addressed by updating the
   condition in intel_pt_do_synth_pebs_sample to fill sample.
   branch_stack if it was synthesized, even if not in the original
   sample_type.

7. Modifying event attributes in perf_event__repipe_attr in-place caused
   SIGSEGV on read-only mmap buffers in file mode and downstream parser
   breakage in pipe mode. Fixed by processing the unmodified attribute
   first, returning immediately in non-pipe mode, and correctly
   synthesizing a new attribute event for pipe output using
   perf_event__synthesize_attr.

8. Potential dangling pointer vulnerability in perf_event__repipe_sample:
   Addressed by restoring the original sample->branch_stack pointer
   before returning.

9. Off-by-one error in sample size check in perf_event__repipe_sample:
   Fixed by checking if sz >= PERF_SAMPLE_MAX_SIZE instead of >.

10. Unadvertised size field left in payload by cut_auxtrace_sample:
    Addressed by excluding the 8-byte size field from the copied
    payload to correctly match the cleared PERF_SAMPLE_AUX bit.

11. Inaccurate sample size calculation and uninitialized memory leaks in
    convert_sample_callchain: Fixed by replacing manual arithmetic with
    perf_event__sample_event_size and adding a bounds check against
    PERF_SAMPLE_MAX_SIZE.

12. Omission of hw_idx in synthesized samples: Fixed by retrieving the
    correct evsel->core.attr.branch_sample_type instead of hardcoding 0 in
    intel-pt.c, arm-spe.c, and cs-etm.c.

Fixes: 0f0aa5e0693c ("perf inject: Add Instruction Tracing support")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-inject.c | 131 +++++++++++++++++++++++++++++++-----
 tools/perf/util/arm-spe.c   |  18 +++--
 tools/perf/util/cs-etm.c    |  21 ++++--
 tools/perf/util/intel-pt.c  |  23 +++++--
 4 files changed, 161 insertions(+), 32 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 6bde3cc173b2..04921fb47b35 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -216,12 +216,23 @@ static int perf_event__repipe_op4_synth(const struct perf_tool *tool,
 	return perf_event__repipe_synth(tool, event);
 }
 
+static int perf_event__repipe_synth_cb(const struct perf_tool *tool,
+				       union perf_event *event,
+				       struct perf_sample *sample __maybe_unused,
+				       struct machine *machine __maybe_unused)
+{
+	return perf_event__repipe_synth(tool, event);
+}
+
 static int perf_event__repipe_attr(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct evlist **pevlist)
 {
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
 						  tool);
+	struct perf_event_attr attr;
+	size_t n_ids;
+	u64 *ids;
 	int ret;
 
 	ret = perf_event__process_attr(tool, event, pevlist);
@@ -232,7 +243,24 @@ static int perf_event__repipe_attr(const struct perf_tool *tool,
 	if (!inject->output.is_pipe)
 		return 0;
 
-	return perf_event__repipe_synth(tool, event);
+	if (!inject->itrace_synth_opts.set)
+		return perf_event__repipe_synth(tool, event);
+
+	attr = event->attr.attr;
+	n_ids = event->header.size - sizeof(event->header) - event->attr.attr.size;
+	n_ids /= sizeof(u64);
+	ids = perf_record_header_attr_id(event);
+
+	attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+	if (inject->itrace_synth_opts.add_last_branch) {
+		attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+		if (attr.size < PERF_ATTR_SIZE_VER2)
+			attr.size = PERF_ATTR_SIZE_VER2;
+		attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+	}
+	return perf_event__synthesize_attr(tool, &attr, (u32)n_ids, ids,
+					   perf_event__repipe_synth_cb);
 }
 
 static int perf_event__repipe_event_update(const struct perf_tool *tool,
@@ -331,8 +359,8 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 				 union perf_event *event,
 				 struct perf_sample *sample)
 {
-	size_t sz1 = sample->aux_sample.data - (void *)event;
-	size_t sz2 = event->header.size - sample->aux_sample.size - sz1;
+	size_t sz1 = sample->aux_sample.data - (void *)event - sizeof(u64);
+	size_t sz2 = event->header.size - sample->aux_sample.size - (sz1 + sizeof(u64));
 	union perf_event *ev;
 
 	if (inject->event_copy == NULL) {
@@ -343,13 +371,12 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 	ev = (union perf_event *)inject->event_copy;
 	if (sz1 > event->header.size || sz2 > event->header.size ||
 	    sz1 + sz2 > event->header.size ||
-	    sz1 < sizeof(struct perf_event_header) + sizeof(u64))
+	    sz1 < sizeof(struct perf_event_header))
 		return event;
 
 	memcpy(ev, event, sz1);
 	memcpy((void *)ev + sz1, (void *)event + event->header.size - sz2, sz2);
 	ev->header.size = sz1 + sz2;
-	((u64 *)((void *)ev + sz1))[-1] = 0;
 
 	return ev;
 }
@@ -376,7 +403,63 @@ static int perf_event__repipe_sample(const struct perf_tool *tool,
 
 	build_id__mark_dso_hit(tool, event, sample, evsel, machine);
 
-	if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
+	if (inject->itrace_synth_opts.set &&
+	    (inject->itrace_synth_opts.last_branch ||
+	     inject->itrace_synth_opts.add_last_branch)) {
+		union perf_event *event_copy = (void *)inject->event_copy;
+		struct branch_stack dummy_bs = { .nr = 0, .hw_idx = 0 };
+		int err;
+		size_t sz;
+		u64 orig_type = evsel->core.attr.sample_type;
+		u64 orig_branch_type = evsel->core.attr.branch_sample_type;
+
+		struct branch_stack *orig_bs = sample->branch_stack;
+
+		if (event_copy == NULL) {
+			inject->event_copy = malloc(PERF_SAMPLE_MAX_SIZE);
+			if (!inject->event_copy)
+				return -ENOMEM;
+
+			event_copy = (void *)inject->event_copy;
+		}
+
+		if (!sample->branch_stack)
+			sample->branch_stack = &dummy_bs;
+
+		if (inject->itrace_synth_opts.add_last_branch) {
+			/* Temporarily add in type bits for synthesis. */
+			evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+			evsel->core.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+		}
+		evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+		sz = perf_event__sample_event_size(sample, evsel->core.attr.sample_type,
+						   evsel->core.attr.read_format,
+						   evsel->core.attr.branch_sample_type);
+
+		if (sz >= PERF_SAMPLE_MAX_SIZE) {
+			pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+			return -EFAULT;
+		}
+
+		event_copy->header.type = PERF_RECORD_SAMPLE;
+		event_copy->header.misc = event->header.misc;
+		event_copy->header.size = sz;
+
+		err = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+						    evsel->core.attr.read_format,
+						    evsel->core.attr.branch_sample_type, sample);
+
+		evsel->core.attr.sample_type = orig_type;
+		evsel->core.attr.branch_sample_type = orig_branch_type;
+		sample->branch_stack = orig_bs;
+
+		if (err) {
+			pr_err("Failed to synthesize sample\n");
+			return err;
+		}
+		event = event_copy;
+	} else if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
 		event = perf_inject__cut_auxtrace_sample(inject, event, sample);
 		if (IS_ERR(event))
 			return PTR_ERR(event);
@@ -397,7 +480,7 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	struct callchain_cursor_node *node;
 	struct thread *thread;
 	u64 sample_type = evsel->core.attr.sample_type;
-	u32 sample_size = event->header.size;
+	size_t sz;
 	u64 i, k;
 	int ret;
 
@@ -456,16 +539,19 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 out:
 	memcpy(event_copy, event, sizeof(event->header));
 
-	/* adjust sample size for stack and regs */
-	sample_size -= sample->user_stack.size;
-	sample_size -= (hweight64(evsel->core.attr.sample_regs_user) + 1) * sizeof(u64);
-	sample_size += (sample->callchain->nr + 1) * sizeof(u64);
-	event_copy->header.size = sample_size;
-
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	ret = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+	sz = perf_event__sample_event_size(sample, sample_type,
+					   evsel->core.attr.read_format,
+					   evsel->core.attr.branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event_copy->header.size = sz;
+
+	ret = perf_event__synthesize_sample(event_copy, sample_type,
 					    evsel->core.attr.read_format,
 					    evsel->core.attr.branch_sample_type, sample);
 	if (ret) {
@@ -2442,12 +2528,25 @@ static int __cmd_inject(struct perf_inject *inject)
 		 * synthesized hardware events, so clear the feature flag.
 		 */
 		if (inject->itrace_synth_opts.set) {
+			struct evsel *evsel;
+
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
-			if (inject->itrace_synth_opts.last_branch ||
-			    inject->itrace_synth_opts.add_last_branch)
+
+			evlist__for_each_entry(session->evlist, evsel) {
+				evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+			}
+
+			if (inject->itrace_synth_opts.add_last_branch) {
 				perf_header__set_feat(&session->header,
 						      HEADER_BRANCH_STACK);
+
+				evlist__for_each_entry(session->evlist, evsel) {
+					evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+					evsel->core.attr.branch_sample_type |=
+						PERF_SAMPLE_BRANCH_HW_INDEX;
+				}
+			}
 		}
 
 		/*
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 24714f516856..ae14bfda9f50 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -487,13 +487,23 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
 	bstack->hw_idx = -1ULL;
 }
 
-static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
+static int arm_spe__inject_event(struct arm_spe *spe, union perf_event *event,
+				 struct perf_sample *sample, u64 type)
 {
+	struct evsel *evsel = NULL;
+	u64 branch_sample_type = 0;
+
+	if (spe->session && spe->session->evlist)
+		evsel = evlist__id2evsel(spe->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
 	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
-							   /*branch_sample_type=*/0);
+							   branch_sample_type);
 	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
-					     /*branch_sample_type=*/0, sample);
+					     branch_sample_type, sample);
 }
 
 static inline int
@@ -505,7 +515,7 @@ arm_spe_deliver_synth_event(struct arm_spe *spe,
 	int ret;
 
 	if (spe->synth_opts.inject) {
-		ret = arm_spe__inject_event(event, sample, spe->sample_type);
+		ret = arm_spe__inject_event(spe, event, sample, spe->sample_type);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 1ebc1a6a5e75..7922e830e0c9 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1422,13 +1422,22 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
 		bs->nr += 1;
 }
 
-static int cs_etm__inject_event(union perf_event *event,
-			       struct perf_sample *sample, u64 type)
+static int cs_etm__inject_event(struct cs_etm_auxtrace *etm, union perf_event *event,
+				struct perf_sample *sample, u64 type)
 {
+	struct evsel *evsel = NULL;
+	u64 branch_sample_type = 0;
+
+	if (etm->session && etm->session->evlist)
+		evsel = evlist__id2evsel(etm->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
 	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
-							   /*branch_sample_type=*/0);
+							   branch_sample_type);
 	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
-					     /*branch_sample_type=*/0, sample);
+					     branch_sample_type, sample);
 }
 
 
@@ -1594,7 +1603,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
 		sample.branch_stack = tidq->last_branch;
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->instructions_sample_type);
 		if (ret)
 			return ret;
@@ -1669,7 +1678,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
 	}
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->branches_sample_type);
 		if (ret)
 			return ret;
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 5142983e3243..f45dbdd4d323 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1728,14 +1728,24 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 	event->sample.header.misc = sample->cpumode;
 }
 
-static int intel_pt_inject_event(union perf_event *event,
+static int intel_pt_inject_event(struct intel_pt *pt, union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
+	struct evsel *evsel = NULL;
+	u64 branch_sample_type = 0;
+
+	if (pt->session && pt->session->evlist)
+		evsel = evlist__id2evsel(pt->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0,
-							   /*branch_sample_type=*/0);
+							   branch_sample_type);
 
 	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
-					     /*branch_sample_type=*/0, sample);
+					     branch_sample_type, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
@@ -1745,7 +1755,7 @@ static inline int intel_pt_opt_inject(struct intel_pt *pt,
 	if (!pt->synth_opts.inject)
 		return 0;
 
-	return intel_pt_inject_event(event, sample, type);
+	return intel_pt_inject_event(pt, event, sample, type);
 }
 
 static int intel_pt_deliver_synth_event(struct intel_pt *pt,
@@ -2489,7 +2499,7 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		intel_pt_add_xmm(intr_regs, pos, items, regs_mask);
 	}
 
-	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+	if ((sample_type | evsel->synth_sample_type) & PERF_SAMPLE_BRANCH_STACK) {
 		if (items->mask[INTEL_PT_LBR_0_POS] ||
 		    items->mask[INTEL_PT_LBR_1_POS] ||
 		    items->mask[INTEL_PT_LBR_2_POS]) {
@@ -2560,7 +2570,8 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		sample.transaction = txn;
 	}
 
-	ret = intel_pt_deliver_synth_event(pt, event, &sample, sample_type);
+	ret = intel_pt_deliver_synth_event(pt, event, &sample,
+					   sample_type | evsel->synth_sample_type);
 	perf_sample__exit(&sample);
 	return ret;
 }
-- 
2.54.0.563.g4f69b47b94-goog

[PATCH v4 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[Ian Rogers]

An intel-pt trace can be turned into LBR events either in perf script
or perf inject with the --itrace=L option. With perf inject the
generated perf.data file failed to be parsed as the sample events were
out of sync with their perf_event_attr. A range of fixes were
required.

This patch was separated from a large perf script refactor that
highlighted the breakage:
https://lore.kernel.org/lkml/20260425224951.174663-1-irogers@google.com/

v4:
 - Avoid temporary regressions in Commit 1:
   * Used local masked sample_type in convert_sample_callchain instead of
     unmasked evsel attribute, preventing heap overflows.
   * Promoted hardware tracer signature changes and dynamic retrieval of
     branch_sample_type to Commit 1, removing hardcoded 0 bugs.
   * Checked sample->evsel first before performing evlist__id2evsel lookup
     to optimize evsel retrieval when already populated.
 - Address critical security and correctness feedback in Commit 2:
   * Added check in perf_event__repipe_attr to prevent n_ids underflow.
   * Fixed early return error path in perf_event__repipe_sample to
     prevent state corruption and dangling pointers on dummy_bs.
   * Ensured perf_inject__cut_auxtrace_sample cuts the 8-byte size field
     even when aux_sample.size is 0 to prevent parser misalignment.
   * Expanded older attributes to PERF_ATTR_SIZE_VER2 in file mode
     within __cmd_inject to prevent silent truncation of
     branch_sample_type.
   * Added bounds checks against PERF_SAMPLE_MAX_SIZE to all hardware
     tracing synthetic helpers to prevent heap buffer overflows.
   * Fixed checkpatch.pl warnings/errors for line-wrapping.

v3:
 - Add missing Fixes: tags on both commits.
 - Refactor perf_event__repipe_attr to avoid in-place modifications on
   read-only mmap buffers, preventing SIGSEGV in file mode and premature
   evsel updates in pipe mode.
 - Use perf_event__synthesize_attr to correctly construct and repipe
   attributes in pipe mode.
 - Replace manual arithmetic in convert_sample_callchain with
   perf_event__sample_event_size to prevent uninitialized memory leaks.
 - Retrieve evsel branch_sample_type dynamically in util/arm-spe.c and
   util/cs-etm.c instead of hardcoding 0, resolving missing hw_idx field
   on synthesized branch stacks.

v2: Response to sashiko fixes for patch 2, Namhyung's acked-by for patch 1.

v1: https://lore.kernel.org/lkml/20260428070328.1880314-1-irogers@google.com/

Ian Rogers (2):
  perf event: Fix size of synthesized sample with branch stacks
  perf inject: Fix itrace branch stack synthesis

 tools/perf/bench/inject-buildid.c  |   9 +-
 tools/perf/builtin-inject.c        | 151 +++++++++++++++++++++++++----
 tools/perf/tests/dlfilter-test.c   |   8 +-
 tools/perf/tests/sample-parsing.c  |   5 +-
 tools/perf/util/arm-spe.c          |  28 +++++-
 tools/perf/util/cs-etm.c           |  28 +++++-
 tools/perf/util/intel-bts.c        |   3 +-
 tools/perf/util/intel-pt.c         |  27 +++++-
 tools/perf/util/synthetic-events.c |  25 +++--
 tools/perf/util/synthetic-events.h |   6 +-
 10 files changed, 242 insertions(+), 48 deletions(-)

-- 
2.54.0.563.g4f69b47b94-goog

[PATCH v4 1/2] perf event: Fix size of synthesized sample with branch stacks

[Ian Rogers]

Synthesizing branch stacks for Intel-PT highlighted an issue where
PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the
perf_event_attr branch_sample_type. This caused an incorrect size
calculation.

Fix the writing of the nr and hw_idx values during sample event
synthesis by passing the branch_sample_type into the sample size
and synthesis functions. Also update hardware tracers (Intel PT,
ARM SPE, CS-ETM) to retrieve and pass their branch_sample_type
dynamically to prevent payload misalignment.

Fixes: d3f85437ad6a ("perf evsel: Support PERF_SAMPLE_BRANCH_HW_INDEX")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/bench/inject-buildid.c  |  9 ++++++---
 tools/perf/builtin-inject.c        | 12 +++++++++---
 tools/perf/tests/dlfilter-test.c   |  8 ++++++--
 tools/perf/tests/sample-parsing.c  |  5 +++--
 tools/perf/util/arm-spe.c          | 28 ++++++++++++++++++++++++----
 tools/perf/util/cs-etm.c           | 28 +++++++++++++++++++++++-----
 tools/perf/util/intel-bts.c        |  3 ++-
 tools/perf/util/intel-pt.c         | 27 +++++++++++++++++++++++----
 tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++-------
 tools/perf/util/synthetic-events.h |  6 ++++--
 10 files changed, 118 insertions(+), 33 deletions(-)

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7f..bfd2c5ec9488 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso,
 
 	event.header.type = PERF_RECORD_SAMPLE;
 	event.header.misc = PERF_RECORD_MISC_USER;
-	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
-
-	perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
+	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	perf_event__synthesize_sample(&event, bench_sample_type,
+				      /*read_format=*/0,
+				      /*branch_sample_type=*/0, &sample);
 
 	return writen(data->input_pipe[1], &event, event.header.size);
 }
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index a2493f1097df..2f20e782c7f2 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -465,8 +465,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	perf_event__synthesize_sample(event_copy, sample_type,
-				      evsel->core.attr.read_format, sample);
+	ret = perf_event__synthesize_sample(event_copy, sample_type,
+					    evsel->core.attr.read_format,
+					    evsel->core.attr.branch_sample_type, sample);
+	if (ret) {
+		pr_err("Failed to synthesize sample\n");
+		return ret;
+	}
 	return perf_event__repipe_synth(tool, event_copy);
 }
 
@@ -1102,7 +1107,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
 	sample_sw.period = sample->period;
 	sample_sw.time	 = sample->time;
 	perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
-				      evsel->core.attr.read_format, &sample_sw);
+				      evsel->core.attr.read_format,
+				      evsel->core.attr.branch_sample_type, &sample_sw);
 	build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
 	ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
 	perf_sample__exit(&sample_sw);
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index e63790c61d53..204663571943 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid
 
 	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.misc = PERF_RECORD_MISC_USER;
-	event->header.size = perf_event__sample_event_size(&sample, sample_type, 0);
-	err = perf_event__synthesize_sample(event, sample_type, 0, &sample);
+	event->header.size = perf_event__sample_event_size(&sample, sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	err = perf_event__synthesize_sample(event, sample_type,
+					    /*read_format=*/0,
+					    /*branch_sample_type=*/0, &sample);
 	if (err)
 		return test_result("perf_event__synthesize_sample() failed", TEST_FAIL);
 
diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
index a7327c942ca2..55f0b73ca20e 100644
--- a/tools/perf/tests/sample-parsing.c
+++ b/tools/perf/tests/sample-parsing.c
@@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 		sample.read.one.lost  = 1;
 	}
 
-	sz = perf_event__sample_event_size(&sample, sample_type, read_format);
+	sz = perf_event__sample_event_size(&sample, sample_type, read_format,
+					   evsel.core.attr.branch_sample_type);
 	bufsz = sz + 4096; /* Add a bit for overrun checking */
 	event = malloc(bufsz);
 	if (!event) {
@@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 	event->header.size = sz;
 
 	err = perf_event__synthesize_sample(event, sample_type, read_format,
-					    &sample);
+					    evsel.core.attr.branch_sample_type, &sample);
 	if (err) {
 		pr_debug("%s failed for sample_type %#"PRIx64", error %d\n",
 			 "perf_event__synthesize_sample", sample_type, err);
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 2b31da231ef3..31f05f467810 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -487,10 +487,30 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
 	bstack->hw_idx = -1ULL;
 }
 
-static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
+static int arm_spe__inject_event(struct arm_spe *spe, union perf_event *event,
+				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && spe->session && spe->session->evlist)
+		evsel = evlist__id2evsel(spe->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int
@@ -502,7 +522,7 @@ arm_spe_deliver_synth_event(struct arm_spe *spe,
 	int ret;
 
 	if (spe->synth_opts.inject) {
-		ret = arm_spe__inject_event(event, sample, spe->sample_type);
+		ret = arm_spe__inject_event(spe, event, sample, spe->sample_type);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 8a639d2e51a4..6ec48de29441 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1422,11 +1422,29 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
 		bs->nr += 1;
 }
 
-static int cs_etm__inject_event(union perf_event *event,
+static int cs_etm__inject_event(struct cs_etm_auxtrace *etm, union perf_event *event,
 			       struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && etm->session && etm->session->evlist)
+		evsel = evlist__id2evsel(etm->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 
@@ -1592,7 +1610,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
 		sample.branch_stack = tidq->last_branch;
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->instructions_sample_type);
 		if (ret)
 			return ret;
@@ -1667,7 +1685,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
 	}
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->branches_sample_type);
 		if (ret)
 			return ret;
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index 382255393fb3..0b18ebd13f7c 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq,
 		event.sample.header.size = bts->branches_event_size;
 		ret = perf_event__synthesize_sample(&event,
 						    bts->branches_sample_type,
-						    0, &sample);
+						    /*read_format=*/0, /*branch_sample_type=*/0,
+						    &sample);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index fc9eec8b54b8..dd2637678b40 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1728,11 +1728,30 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 	event->sample.header.misc = sample->cpumode;
 }
 
-static int intel_pt_inject_event(union perf_event *event,
+static int intel_pt_inject_event(struct intel_pt *pt, union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && pt->session && pt->session->evlist)
+		evsel = evlist__id2evsel(pt->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
@@ -1742,7 +1761,7 @@ static inline int intel_pt_opt_inject(struct intel_pt *pt,
 	if (!pt->synth_opts.inject)
 		return 0;
 
-	return intel_pt_inject_event(event, sample, type);
+	return intel_pt_inject_event(pt, event, sample, type);
 }
 
 static int intel_pt_deliver_synth_event(struct intel_pt *pt,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 85bee747f4cd..2461f25a4d7d 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool,
 	return process(tool, (union perf_event *) &event, NULL, machine);
 }
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format)
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format,
+				     u64 branch_sample_type)
 {
 	size_t sz, result = sizeof(struct perf_record_sample);
 
@@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
+		/* nr */
+		sz += sizeof(u64);
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)
+			sz += sizeof(u64);
 		result += sz;
 	}
 
@@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format,
 }
 
 int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
-				  const struct perf_sample *sample)
+				  u64 branch_sample_type, const struct perf_sample *sample)
 {
 	__u64 *array;
 	size_t sz;
@@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
-		memcpy(array, sample->branch_stack, sz);
+
+		*array++ = sample->branch_stack->nr;
+
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) {
+			if (sample->no_hw_idx)
+				*array++ = 0;
+			else
+				*array++ = sample->branch_stack->hw_idx;
+		}
+
+		memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz);
 		array = (void *)array + sz;
 	}
 
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index b0edad0c3100..8c7f49f9ccf5 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_
 int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
+int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
+				  u64 branch_sample_type, const struct perf_sample *sample);
 int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
 int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
@@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session,
 
 int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
+				     u64 read_format, u64 branch_sample_type);
 
 int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
-- 
2.54.0.563.g4f69b47b94-goog

[PATCH v4 2/2] perf inject: Fix itrace branch stack synthesis

[Ian Rogers]

When using "perf inject --itrace=L" to synthesize branch stacks from
AUX data, several issues caused failures with the generated file:

1. The synthesized samples were delivered without the
   PERF_SAMPLE_BRANCH_STACK flag if it was not in the original event's
   sample_type. Fixed by using sample_type | evsel->synth_sample_type
   in intel_pt_do_synth_pebs_sample.

2. Modifying evsel->core.attr.sample_type early in __cmd_inject caused
   parse failures for subsequent records in the input file. Fixed by
   moving this modification to just before writing the header.

3. perf_event__repipe_sample was narrowed to only synthesize samples
   when branch stack injection was requested, and restored the use of
   perf_inject__cut_auxtrace_sample as a fallback to preserve
   functionality.

4. Potential Heap Overflow in perf_event__repipe_sample: Addressed by
   adding a check that prints an error and returns -EFAULT if the
   calculated event size exceeds PERF_SAMPLE_MAX_SIZE.

5. Header vs Payload Mismatch in __cmd_inject: Addressed by narrowing
   the condition so that HEADER_BRANCH_STACK is only set in the file
   header if add_last_branch was true.

6. NULL Pointer Dereference in intel-pt.c: Addressed by updating the
   condition in intel_pt_do_synth_pebs_sample to fill sample.
   branch_stack if it warrants synthesis, even if not in the original
   sample_type.

7. Modifying event attributes in perf_event__repipe_attr in-place caused
   SIGSEGV on read-only mmap buffers in file mode and downstream parser
   breakage in pipe mode. Fixed by processing the unmodified attribute
   first, returning immediately in non-pipe mode, and correctly
   synthesizing a new attribute event for pipe output using
   perf_event__synthesize_attr. Also added a size validation check to
   prevent n_ids underflow when parsing header size.

8. Potential dangling pointer vulnerability in perf_event__repipe_sample:
   Addressed by restoring the original sample->branch_stack pointer
   before returning, including on early error return paths.

9. Off-by-one error in sample size check in perf_event__repipe_sample:
   Fixed by checking if sz >= PERF_SAMPLE_MAX_SIZE instead of >.

10. Unadvertised size field left in payload by cut_auxtrace_sample:
    Addressed by excluding the 8-byte size field from the copied
    payload to correctly match the cleared PERF_SAMPLE_AUX bit. Cut
    the AUX sample payload even if size is 0.

11. Inaccurate sample size calculation and uninitialized memory leaks in
    convert_sample_callchain: Fixed by replacing manual arithmetic with
    perf_event__sample_event_size and adding a bounds check against
    PERF_SAMPLE_MAX_SIZE.

12. Omission of branch_sample_type in file headers: Addressed by
    expanding older, smaller attributes to PERF_ATTR_SIZE_VER2 in
    __cmd_inject to ensure branch_sample_type is not silently omitted.

Fixes: 0f0aa5e0693c ("perf inject: Add Instruction Tracing support")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-inject.c | 139 ++++++++++++++++++++++++++++++++----
 1 file changed, 124 insertions(+), 15 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 2f20e782c7f2..3d6ec2c7f990 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -216,12 +216,23 @@ static int perf_event__repipe_op4_synth(const struct perf_tool *tool,
 	return perf_event__repipe_synth(tool, event);
 }
 
+static int perf_event__repipe_synth_cb(const struct perf_tool *tool,
+				       union perf_event *event,
+				       struct perf_sample *sample __maybe_unused,
+				       struct machine *machine __maybe_unused)
+{
+	return perf_event__repipe_synth(tool, event);
+}
+
 static int perf_event__repipe_attr(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct evlist **pevlist)
 {
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
 						  tool);
+	struct perf_event_attr attr;
+	size_t n_ids;
+	u64 *ids;
 	int ret;
 
 	ret = perf_event__process_attr(tool, event, pevlist);
@@ -232,7 +243,28 @@ static int perf_event__repipe_attr(const struct perf_tool *tool,
 	if (!inject->output.is_pipe)
 		return 0;
 
-	return perf_event__repipe_synth(tool, event);
+	if (!inject->itrace_synth_opts.set)
+		return perf_event__repipe_synth(tool, event);
+
+	attr = event->attr.attr;
+	if (event->header.size < sizeof(event->header) + event->attr.attr.size) {
+		pr_err("Attribute event size %u is too small\n", event->header.size);
+		return -EINVAL;
+	}
+	n_ids = event->header.size - sizeof(event->header) - event->attr.attr.size;
+	n_ids /= sizeof(u64);
+	ids = perf_record_header_attr_id(event);
+
+	attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+	if (inject->itrace_synth_opts.add_last_branch) {
+		attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+		if (attr.size < PERF_ATTR_SIZE_VER2)
+			attr.size = PERF_ATTR_SIZE_VER2;
+		attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+	}
+	return perf_event__synthesize_attr(tool, &attr, (u32)n_ids, ids,
+					   perf_event__repipe_synth_cb);
 }
 
 static int perf_event__repipe_event_update(const struct perf_tool *tool,
@@ -331,8 +363,8 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 				 union perf_event *event,
 				 struct perf_sample *sample)
 {
-	size_t sz1 = sample->aux_sample.data - (void *)event;
-	size_t sz2 = event->header.size - sample->aux_sample.size - sz1;
+	size_t sz1 = sample->aux_sample.data - (void *)event - sizeof(u64);
+	size_t sz2 = event->header.size - sample->aux_sample.size - (sz1 + sizeof(u64));
 	union perf_event *ev;
 
 	if (inject->event_copy == NULL) {
@@ -343,13 +375,12 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 	ev = (union perf_event *)inject->event_copy;
 	if (sz1 > event->header.size || sz2 > event->header.size ||
 	    sz1 + sz2 > event->header.size ||
-	    sz1 < sizeof(struct perf_event_header) + sizeof(u64))
+	    sz1 < sizeof(struct perf_event_header))
 		return event;
 
 	memcpy(ev, event, sz1);
 	memcpy((void *)ev + sz1, (void *)event + event->header.size - sz2, sz2);
 	ev->header.size = sz1 + sz2;
-	((u64 *)((void *)ev + sz1))[-1] = 0;
 
 	return ev;
 }
@@ -376,7 +407,67 @@ static int perf_event__repipe_sample(const struct perf_tool *tool,
 
 	build_id__mark_dso_hit(tool, event, sample, evsel, machine);
 
-	if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
+	if (inject->itrace_synth_opts.set &&
+	    (inject->itrace_synth_opts.last_branch ||
+	     inject->itrace_synth_opts.add_last_branch)) {
+		union perf_event *event_copy = (void *)inject->event_copy;
+		struct branch_stack dummy_bs = { .nr = 0, .hw_idx = 0 };
+		int err;
+		size_t sz;
+		u64 orig_type = evsel->core.attr.sample_type;
+		u64 orig_branch_type = evsel->core.attr.branch_sample_type;
+
+		struct branch_stack *orig_bs = sample->branch_stack;
+
+		if (event_copy == NULL) {
+			inject->event_copy = malloc(PERF_SAMPLE_MAX_SIZE);
+			if (!inject->event_copy)
+				return -ENOMEM;
+
+			event_copy = (void *)inject->event_copy;
+		}
+
+		if (!sample->branch_stack)
+			sample->branch_stack = &dummy_bs;
+
+		if (inject->itrace_synth_opts.add_last_branch) {
+			/* Temporarily add in type bits for synthesis. */
+			evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+			evsel->core.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+		}
+		evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+		sz = perf_event__sample_event_size(sample, evsel->core.attr.sample_type,
+						   evsel->core.attr.read_format,
+						   evsel->core.attr.branch_sample_type);
+
+		if (sz >= PERF_SAMPLE_MAX_SIZE) {
+			pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+			evsel->core.attr.sample_type = orig_type;
+			evsel->core.attr.branch_sample_type = orig_branch_type;
+			sample->branch_stack = orig_bs;
+			return -EFAULT;
+		}
+
+		event_copy->header.type = PERF_RECORD_SAMPLE;
+		event_copy->header.misc = event->header.misc;
+		event_copy->header.size = sz;
+
+		err = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+						    evsel->core.attr.read_format,
+						    evsel->core.attr.branch_sample_type, sample);
+
+		evsel->core.attr.sample_type = orig_type;
+		evsel->core.attr.branch_sample_type = orig_branch_type;
+		sample->branch_stack = orig_bs;
+
+		if (err) {
+			pr_err("Failed to synthesize sample\n");
+			return err;
+		}
+		event = event_copy;
+	} else if (inject->itrace_synth_opts.set &&
+		   (evsel->core.attr.sample_type & PERF_SAMPLE_AUX)) {
 		event = perf_inject__cut_auxtrace_sample(inject, event, sample);
 		if (IS_ERR(event))
 			return PTR_ERR(event);
@@ -397,7 +488,7 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	struct callchain_cursor_node *node;
 	struct thread *thread;
 	u64 sample_type = evsel->core.attr.sample_type;
-	u32 sample_size = event->header.size;
+	size_t sz;
 	u64 i, k;
 	int ret;
 
@@ -456,15 +547,18 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 out:
 	memcpy(event_copy, event, sizeof(event->header));
 
-	/* adjust sample size for stack and regs */
-	sample_size -= sample->user_stack.size;
-	sample_size -= (hweight64(evsel->core.attr.sample_regs_user) + 1) * sizeof(u64);
-	sample_size += (sample->callchain->nr + 1) * sizeof(u64);
-	event_copy->header.size = sample_size;
-
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
+	sz = perf_event__sample_event_size(sample, sample_type,
+					   evsel->core.attr.read_format,
+					   evsel->core.attr.branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event_copy->header.size = sz;
+
 	ret = perf_event__synthesize_sample(event_copy, sample_type,
 					    evsel->core.attr.read_format,
 					    evsel->core.attr.branch_sample_type, sample);
@@ -2442,12 +2536,27 @@ static int __cmd_inject(struct perf_inject *inject)
 		 * synthesized hardware events, so clear the feature flag.
 		 */
 		if (inject->itrace_synth_opts.set) {
+			struct evsel *evsel;
+
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
-			if (inject->itrace_synth_opts.last_branch ||
-			    inject->itrace_synth_opts.add_last_branch)
+
+			evlist__for_each_entry(session->evlist, evsel) {
+				evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+			}
+
+			if (inject->itrace_synth_opts.add_last_branch) {
 				perf_header__set_feat(&session->header,
 						      HEADER_BRANCH_STACK);
+
+				evlist__for_each_entry(session->evlist, evsel) {
+					evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+					if (evsel->core.attr.size < PERF_ATTR_SIZE_VER2)
+						evsel->core.attr.size = PERF_ATTR_SIZE_VER2;
+					evsel->core.attr.branch_sample_type |=
+						PERF_SAMPLE_BRANCH_HW_INDEX;
+				}
+			}
 		}
 
 		/*
-- 
2.54.0.563.g4f69b47b94-goog

[PATCH v5 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[Ian Rogers]

An intel-pt trace can be turned into LBR events either in perf script
or perf inject with the --itrace=L option. With perf inject the
generated perf.data file failed to be parsed as the sample events were
out of sync with their perf_event_attr. A range of fixes were
required.

This patch was separated from a large perf script refactor that
highlighted the breakage:
https://lore.kernel.org/lkml/20260425224951.174663-1-irogers@google.com/

v5:
 - Restored the missing PEBS branch stack synthesis fixes in intel-pt.c
   which were accidentally dropped in a previous rebase/conflict
   resolution.
 - Addressed the pipe mode size mismatch and ID array out-of-bounds read:
   * Safely copy the incoming attribute payload using min_t and
     memset zero, preventing trailing ID corruption.
   * Explicitly set the synthesized event's attr.size to match the tool's
     physical sizeof(struct perf_event_attr), guaranteeing perfect offset
     alignment and removing any risk of hallucinated/garbage IDs or
     underflow out-of-bounds reads.
 - Refactored both commit descriptions to strictly focus on code changes,
   deferring meta-commentary and implementation details exclusively to
   the cover letter.

v4:
 - Avoid temporary regressions in Commit 1:
   * Used local masked sample_type in convert_sample_callchain instead of
     unmasked evsel attribute, preventing heap overflows.
   * Promoted hardware tracer signature changes and dynamic retrieval of
     branch_sample_type to Commit 1, removing hardcoded 0 bugs.
   * Checked sample->evsel first before performing evlist__id2evsel lookup
     to optimize evsel retrieval when already populated.
 - Address critical security and correctness feedback in Commit 2:
   * Added check in perf_event__repipe_attr to prevent n_ids underflow.
   * Fixed early return error path in perf_event__repipe_sample to
     prevent state corruption and dangling pointers on dummy_bs.
   * Ensured perf_inject__cut_auxtrace_sample cuts the 8-byte size field
     even when aux_sample.size is 0 to prevent parser misalignment.
   * Expanded older attributes to PERF_ATTR_SIZE_VER2 in file mode
     within __cmd_inject to prevent silent truncation of
     branch_sample_type.
   * Added bounds checks against PERF_SAMPLE_MAX_SIZE to all hardware
     tracing synthetic helpers to prevent heap buffer overflows.
   * Fixed checkpatch.pl warnings/errors for line-wrapping.

v3:
 - Add missing Fixes: tags on both commits.
 - Refactor perf_event__repipe_attr to avoid in-place modifications on
   read-only mmap buffers, preventing SIGSEGV in file mode and premature
   evsel updates in pipe mode.
 - Use perf_event__synthesize_attr to correctly construct and repipe
   attributes in pipe mode.
 - Replace manual arithmetic in convert_sample_callchain with
   perf_event__sample_event_size to prevent uninitialized memory leaks.
 - Retrieve evsel branch_sample_type dynamically in util/arm-spe.c and
   util/cs-etm.c instead of hardcoding 0, resolving missing hw_idx field
   on synthesized branch stacks.

v2: Response to sashiko fixes for patch 2, Namhyung's acked-by for patch 1.

v1: https://lore.kernel.org/lkml/20260428070328.1880314-1-irogers@google.com/

Ian Rogers (2):
  perf event: Fix size of synthesized sample with branch stacks
  perf inject: Fix itrace branch stack synthesis

 tools/perf/bench/inject-buildid.c  |   9 +-
 tools/perf/builtin-inject.c        | 153 +++++++++++++++++++++++++----
 tools/perf/tests/dlfilter-test.c   |   8 +-
 tools/perf/tests/sample-parsing.c  |   5 +-
 tools/perf/util/arm-spe.c          |  28 +++++-
 tools/perf/util/cs-etm.c           |  28 +++++-
 tools/perf/util/intel-bts.c        |   3 +-
 tools/perf/util/intel-pt.c         |  32 ++++--
 tools/perf/util/synthetic-events.c |  25 +++--
 tools/perf/util/synthetic-events.h |   6 +-
 10 files changed, 247 insertions(+), 50 deletions(-)

-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v5 1/2] perf event: Fix size of synthesized sample with branch stacks

[Ian Rogers]

Synthesizing branch stacks for Intel-PT highlighted an issue where
PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the
perf_event_attr branch_sample_type. This caused an incorrect size
calculation.

Fix the writing of the nr and hw_idx values during sample event
synthesis by passing the branch_sample_type into the sample size
and synthesis functions. Also update hardware tracers (Intel PT,
ARM SPE, CS-ETM) to retrieve and pass their branch_sample_type
dynamically to prevent payload misalignment.

Fixes: d3f85437ad6a ("perf evsel: Support PERF_SAMPLE_BRANCH_HW_INDEX")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/bench/inject-buildid.c  |  9 ++++++---
 tools/perf/builtin-inject.c        | 12 +++++++++---
 tools/perf/tests/dlfilter-test.c   |  8 ++++++--
 tools/perf/tests/sample-parsing.c  |  5 +++--
 tools/perf/util/arm-spe.c          | 28 ++++++++++++++++++++++++----
 tools/perf/util/cs-etm.c           | 28 +++++++++++++++++++++++-----
 tools/perf/util/intel-bts.c        |  3 ++-
 tools/perf/util/intel-pt.c         | 27 +++++++++++++++++++++++----
 tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++-------
 tools/perf/util/synthetic-events.h |  6 ++++--
 10 files changed, 118 insertions(+), 33 deletions(-)

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7f..bfd2c5ec9488 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso,
 
 	event.header.type = PERF_RECORD_SAMPLE;
 	event.header.misc = PERF_RECORD_MISC_USER;
-	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
-
-	perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
+	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	perf_event__synthesize_sample(&event, bench_sample_type,
+				      /*read_format=*/0,
+				      /*branch_sample_type=*/0, &sample);
 
 	return writen(data->input_pipe[1], &event, event.header.size);
 }
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index a2493f1097df..2f20e782c7f2 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -465,8 +465,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	perf_event__synthesize_sample(event_copy, sample_type,
-				      evsel->core.attr.read_format, sample);
+	ret = perf_event__synthesize_sample(event_copy, sample_type,
+					    evsel->core.attr.read_format,
+					    evsel->core.attr.branch_sample_type, sample);
+	if (ret) {
+		pr_err("Failed to synthesize sample\n");
+		return ret;
+	}
 	return perf_event__repipe_synth(tool, event_copy);
 }
 
@@ -1102,7 +1107,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
 	sample_sw.period = sample->period;
 	sample_sw.time	 = sample->time;
 	perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
-				      evsel->core.attr.read_format, &sample_sw);
+				      evsel->core.attr.read_format,
+				      evsel->core.attr.branch_sample_type, &sample_sw);
 	build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
 	ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
 	perf_sample__exit(&sample_sw);
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index e63790c61d53..204663571943 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid
 
 	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.misc = PERF_RECORD_MISC_USER;
-	event->header.size = perf_event__sample_event_size(&sample, sample_type, 0);
-	err = perf_event__synthesize_sample(event, sample_type, 0, &sample);
+	event->header.size = perf_event__sample_event_size(&sample, sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	err = perf_event__synthesize_sample(event, sample_type,
+					    /*read_format=*/0,
+					    /*branch_sample_type=*/0, &sample);
 	if (err)
 		return test_result("perf_event__synthesize_sample() failed", TEST_FAIL);
 
diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
index a7327c942ca2..55f0b73ca20e 100644
--- a/tools/perf/tests/sample-parsing.c
+++ b/tools/perf/tests/sample-parsing.c
@@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 		sample.read.one.lost  = 1;
 	}
 
-	sz = perf_event__sample_event_size(&sample, sample_type, read_format);
+	sz = perf_event__sample_event_size(&sample, sample_type, read_format,
+					   evsel.core.attr.branch_sample_type);
 	bufsz = sz + 4096; /* Add a bit for overrun checking */
 	event = malloc(bufsz);
 	if (!event) {
@@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 	event->header.size = sz;
 
 	err = perf_event__synthesize_sample(event, sample_type, read_format,
-					    &sample);
+					    evsel.core.attr.branch_sample_type, &sample);
 	if (err) {
 		pr_debug("%s failed for sample_type %#"PRIx64", error %d\n",
 			 "perf_event__synthesize_sample", sample_type, err);
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 2b31da231ef3..31f05f467810 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -487,10 +487,30 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
 	bstack->hw_idx = -1ULL;
 }
 
-static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
+static int arm_spe__inject_event(struct arm_spe *spe, union perf_event *event,
+				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && spe->session && spe->session->evlist)
+		evsel = evlist__id2evsel(spe->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int
@@ -502,7 +522,7 @@ arm_spe_deliver_synth_event(struct arm_spe *spe,
 	int ret;
 
 	if (spe->synth_opts.inject) {
-		ret = arm_spe__inject_event(event, sample, spe->sample_type);
+		ret = arm_spe__inject_event(spe, event, sample, spe->sample_type);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 8a639d2e51a4..6ec48de29441 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1422,11 +1422,29 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
 		bs->nr += 1;
 }
 
-static int cs_etm__inject_event(union perf_event *event,
+static int cs_etm__inject_event(struct cs_etm_auxtrace *etm, union perf_event *event,
 			       struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && etm->session && etm->session->evlist)
+		evsel = evlist__id2evsel(etm->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 
@@ -1592,7 +1610,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
 		sample.branch_stack = tidq->last_branch;
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->instructions_sample_type);
 		if (ret)
 			return ret;
@@ -1667,7 +1685,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
 	}
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->branches_sample_type);
 		if (ret)
 			return ret;
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index 382255393fb3..0b18ebd13f7c 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq,
 		event.sample.header.size = bts->branches_event_size;
 		ret = perf_event__synthesize_sample(&event,
 						    bts->branches_sample_type,
-						    0, &sample);
+						    /*read_format=*/0, /*branch_sample_type=*/0,
+						    &sample);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index fc9eec8b54b8..dd2637678b40 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1728,11 +1728,30 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 	event->sample.header.misc = sample->cpumode;
 }
 
-static int intel_pt_inject_event(union perf_event *event,
+static int intel_pt_inject_event(struct intel_pt *pt, union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && pt->session && pt->session->evlist)
+		evsel = evlist__id2evsel(pt->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
@@ -1742,7 +1761,7 @@ static inline int intel_pt_opt_inject(struct intel_pt *pt,
 	if (!pt->synth_opts.inject)
 		return 0;
 
-	return intel_pt_inject_event(event, sample, type);
+	return intel_pt_inject_event(pt, event, sample, type);
 }
 
 static int intel_pt_deliver_synth_event(struct intel_pt *pt,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 85bee747f4cd..2461f25a4d7d 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool,
 	return process(tool, (union perf_event *) &event, NULL, machine);
 }
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format)
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format,
+				     u64 branch_sample_type)
 {
 	size_t sz, result = sizeof(struct perf_record_sample);
 
@@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
+		/* nr */
+		sz += sizeof(u64);
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)
+			sz += sizeof(u64);
 		result += sz;
 	}
 
@@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format,
 }
 
 int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
-				  const struct perf_sample *sample)
+				  u64 branch_sample_type, const struct perf_sample *sample)
 {
 	__u64 *array;
 	size_t sz;
@@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
-		memcpy(array, sample->branch_stack, sz);
+
+		*array++ = sample->branch_stack->nr;
+
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) {
+			if (sample->no_hw_idx)
+				*array++ = 0;
+			else
+				*array++ = sample->branch_stack->hw_idx;
+		}
+
+		memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz);
 		array = (void *)array + sz;
 	}
 
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index b0edad0c3100..8c7f49f9ccf5 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_
 int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
+int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
+				  u64 branch_sample_type, const struct perf_sample *sample);
 int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
 int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
@@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session,
 
 int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
+				     u64 read_format, u64 branch_sample_type);
 
 int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v5 2/2] perf inject: Fix itrace branch stack synthesis

[Ian Rogers]

When using "perf inject --itrace=L" to synthesize branch stacks from
AUX data, several issues caused failures with the generated file:

1. The synthesized samples were delivered without the
   PERF_SAMPLE_BRANCH_STACK flag if it was not in the original event's
   sample_type. Fixed by using sample_type | evsel->synth_sample_type
   in intel_pt_do_synth_pebs_sample.

2. Modifying evsel->core.attr.sample_type early in __cmd_inject caused
   parse failures for subsequent records in the input file. Fixed by
   moving this modification to just before writing the header.

3. perf_event__repipe_sample was narrowed to only synthesize samples
   when branch stack injection was requested, and restored the use of
   perf_inject__cut_auxtrace_sample as a fallback to preserve
   functionality.

4. Potential Heap Overflow in perf_event__repipe_sample: Addressed by
   adding a check that prints an error and returns -EFAULT if the
   calculated event size exceeds PERF_SAMPLE_MAX_SIZE.

5. Header vs Payload Mismatch in __cmd_inject: Addressed by narrowing
   the condition so that HEADER_BRANCH_STACK is only set in the file
   header if add_last_branch was true.

6. NULL Pointer Dereference in intel-pt.c: Addressed by updating the
   condition in intel_pt_do_synth_pebs_sample to fill sample.
   branch_stack if it warrants synthesis, even if not in the original
   sample_type.

7. Modifying event attributes in perf_event__repipe_attr in-place caused
   SIGSEGV on read-only mmap buffers in file mode and downstream parser
   breakage in pipe mode. Fixed by processing the unmodified attribute
   first, returning immediately in non-pipe mode, and correctly
   synthesizing a new attribute event for pipe output using
   perf_event__synthesize_attr. Also added a size validation check to
   prevent n_ids underflow when parsing header size.

8. Potential dangling pointer vulnerability in perf_event__repipe_sample:
   Addressed by restoring the original sample->branch_stack pointer
   before returning, including on early error return paths.

9. Off-by-one error in sample size check in perf_event__repipe_sample:
   Fixed by checking if sz >= PERF_SAMPLE_MAX_SIZE instead of >.

10. Unadvertised size field left in payload by cut_auxtrace_sample:
    Addressed by excluding the 8-byte size field from the copied
    payload to correctly match the cleared PERF_SAMPLE_AUX bit. Cut
    the AUX sample payload even if size is 0.

11. Inaccurate sample size calculation and uninitialized memory leaks in
    convert_sample_callchain: Fixed by replacing manual arithmetic with
    perf_event__sample_event_size and adding a bounds check against
    PERF_SAMPLE_MAX_SIZE.

12. Omission of branch_sample_type in file headers: Addressed by
    expanding older, smaller attributes to PERF_ATTR_SIZE_VER2 in
    __cmd_inject to ensure branch_sample_type is not silently omitted.

Fixes: 0f0aa5e0693c ("perf inject: Add Instruction Tracing support")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-inject.c | 141 ++++++++++++++++++++++++++++++++----
 tools/perf/util/intel-pt.c  |   5 +-
 2 files changed, 129 insertions(+), 17 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 2f20e782c7f2..dbc3f640815d 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -216,12 +216,23 @@ static int perf_event__repipe_op4_synth(const struct perf_tool *tool,
 	return perf_event__repipe_synth(tool, event);
 }
 
+static int perf_event__repipe_synth_cb(const struct perf_tool *tool,
+				       union perf_event *event,
+				       struct perf_sample *sample __maybe_unused,
+				       struct machine *machine __maybe_unused)
+{
+	return perf_event__repipe_synth(tool, event);
+}
+
 static int perf_event__repipe_attr(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct evlist **pevlist)
 {
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
 						  tool);
+	struct perf_event_attr attr;
+	size_t n_ids;
+	u64 *ids;
 	int ret;
 
 	ret = perf_event__process_attr(tool, event, pevlist);
@@ -232,7 +243,30 @@ static int perf_event__repipe_attr(const struct perf_tool *tool,
 	if (!inject->output.is_pipe)
 		return 0;
 
-	return perf_event__repipe_synth(tool, event);
+	if (!inject->itrace_synth_opts.set)
+		return perf_event__repipe_synth(tool, event);
+
+	memset(&attr, 0, sizeof(attr));
+	memcpy(&attr, &event->attr.attr,
+	       min_t(size_t, sizeof(attr), (size_t)event->attr.attr.size));
+
+	if (event->header.size < sizeof(event->header) + event->attr.attr.size) {
+		pr_err("Attribute event size %u is too small\n", event->header.size);
+		return -EINVAL;
+	}
+	n_ids = event->header.size - sizeof(event->header) - event->attr.attr.size;
+	n_ids /= sizeof(u64);
+	ids = perf_record_header_attr_id(event);
+
+	attr.size = sizeof(struct perf_event_attr);
+	attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+	if (inject->itrace_synth_opts.add_last_branch) {
+		attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+		attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+	}
+	return perf_event__synthesize_attr(tool, &attr, (u32)n_ids, ids,
+					   perf_event__repipe_synth_cb);
 }
 
 static int perf_event__repipe_event_update(const struct perf_tool *tool,
@@ -331,8 +365,8 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 				 union perf_event *event,
 				 struct perf_sample *sample)
 {
-	size_t sz1 = sample->aux_sample.data - (void *)event;
-	size_t sz2 = event->header.size - sample->aux_sample.size - sz1;
+	size_t sz1 = sample->aux_sample.data - (void *)event - sizeof(u64);
+	size_t sz2 = event->header.size - sample->aux_sample.size - (sz1 + sizeof(u64));
 	union perf_event *ev;
 
 	if (inject->event_copy == NULL) {
@@ -343,13 +377,12 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 	ev = (union perf_event *)inject->event_copy;
 	if (sz1 > event->header.size || sz2 > event->header.size ||
 	    sz1 + sz2 > event->header.size ||
-	    sz1 < sizeof(struct perf_event_header) + sizeof(u64))
+	    sz1 < sizeof(struct perf_event_header))
 		return event;
 
 	memcpy(ev, event, sz1);
 	memcpy((void *)ev + sz1, (void *)event + event->header.size - sz2, sz2);
 	ev->header.size = sz1 + sz2;
-	((u64 *)((void *)ev + sz1))[-1] = 0;
 
 	return ev;
 }
@@ -376,7 +409,67 @@ static int perf_event__repipe_sample(const struct perf_tool *tool,
 
 	build_id__mark_dso_hit(tool, event, sample, evsel, machine);
 
-	if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
+	if (inject->itrace_synth_opts.set &&
+	    (inject->itrace_synth_opts.last_branch ||
+	     inject->itrace_synth_opts.add_last_branch)) {
+		union perf_event *event_copy = (void *)inject->event_copy;
+		struct branch_stack dummy_bs = { .nr = 0, .hw_idx = 0 };
+		int err;
+		size_t sz;
+		u64 orig_type = evsel->core.attr.sample_type;
+		u64 orig_branch_type = evsel->core.attr.branch_sample_type;
+
+		struct branch_stack *orig_bs = sample->branch_stack;
+
+		if (event_copy == NULL) {
+			inject->event_copy = malloc(PERF_SAMPLE_MAX_SIZE);
+			if (!inject->event_copy)
+				return -ENOMEM;
+
+			event_copy = (void *)inject->event_copy;
+		}
+
+		if (!sample->branch_stack)
+			sample->branch_stack = &dummy_bs;
+
+		if (inject->itrace_synth_opts.add_last_branch) {
+			/* Temporarily add in type bits for synthesis. */
+			evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+			evsel->core.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+		}
+		evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+		sz = perf_event__sample_event_size(sample, evsel->core.attr.sample_type,
+						   evsel->core.attr.read_format,
+						   evsel->core.attr.branch_sample_type);
+
+		if (sz >= PERF_SAMPLE_MAX_SIZE) {
+			pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+			evsel->core.attr.sample_type = orig_type;
+			evsel->core.attr.branch_sample_type = orig_branch_type;
+			sample->branch_stack = orig_bs;
+			return -EFAULT;
+		}
+
+		event_copy->header.type = PERF_RECORD_SAMPLE;
+		event_copy->header.misc = event->header.misc;
+		event_copy->header.size = sz;
+
+		err = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+						    evsel->core.attr.read_format,
+						    evsel->core.attr.branch_sample_type, sample);
+
+		evsel->core.attr.sample_type = orig_type;
+		evsel->core.attr.branch_sample_type = orig_branch_type;
+		sample->branch_stack = orig_bs;
+
+		if (err) {
+			pr_err("Failed to synthesize sample\n");
+			return err;
+		}
+		event = event_copy;
+	} else if (inject->itrace_synth_opts.set &&
+		   (evsel->core.attr.sample_type & PERF_SAMPLE_AUX)) {
 		event = perf_inject__cut_auxtrace_sample(inject, event, sample);
 		if (IS_ERR(event))
 			return PTR_ERR(event);
@@ -397,7 +490,7 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	struct callchain_cursor_node *node;
 	struct thread *thread;
 	u64 sample_type = evsel->core.attr.sample_type;
-	u32 sample_size = event->header.size;
+	size_t sz;
 	u64 i, k;
 	int ret;
 
@@ -456,15 +549,18 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 out:
 	memcpy(event_copy, event, sizeof(event->header));
 
-	/* adjust sample size for stack and regs */
-	sample_size -= sample->user_stack.size;
-	sample_size -= (hweight64(evsel->core.attr.sample_regs_user) + 1) * sizeof(u64);
-	sample_size += (sample->callchain->nr + 1) * sizeof(u64);
-	event_copy->header.size = sample_size;
-
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
+	sz = perf_event__sample_event_size(sample, sample_type,
+					   evsel->core.attr.read_format,
+					   evsel->core.attr.branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event_copy->header.size = sz;
+
 	ret = perf_event__synthesize_sample(event_copy, sample_type,
 					    evsel->core.attr.read_format,
 					    evsel->core.attr.branch_sample_type, sample);
@@ -2442,12 +2538,27 @@ static int __cmd_inject(struct perf_inject *inject)
 		 * synthesized hardware events, so clear the feature flag.
 		 */
 		if (inject->itrace_synth_opts.set) {
+			struct evsel *evsel;
+
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
-			if (inject->itrace_synth_opts.last_branch ||
-			    inject->itrace_synth_opts.add_last_branch)
+
+			evlist__for_each_entry(session->evlist, evsel) {
+				evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+			}
+
+			if (inject->itrace_synth_opts.add_last_branch) {
 				perf_header__set_feat(&session->header,
 						      HEADER_BRANCH_STACK);
+
+				evlist__for_each_entry(session->evlist, evsel) {
+					evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+					if (evsel->core.attr.size < PERF_ATTR_SIZE_VER2)
+						evsel->core.attr.size = PERF_ATTR_SIZE_VER2;
+					evsel->core.attr.branch_sample_type |=
+						PERF_SAMPLE_BRANCH_HW_INDEX;
+				}
+			}
 		}
 
 		/*
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index dd2637678b40..7153b48cfe63 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -2505,7 +2505,7 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		intel_pt_add_xmm(intr_regs, pos, items, regs_mask);
 	}
 
-	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+	if ((sample_type | evsel->synth_sample_type) & PERF_SAMPLE_BRANCH_STACK) {
 		if (items->mask[INTEL_PT_LBR_0_POS] ||
 		    items->mask[INTEL_PT_LBR_1_POS] ||
 		    items->mask[INTEL_PT_LBR_2_POS]) {
@@ -2576,7 +2576,8 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		sample.transaction = txn;
 	}
 
-	ret = intel_pt_deliver_synth_event(pt, event, &sample, sample_type);
+	ret = intel_pt_deliver_synth_event(pt, event, &sample,
+					   sample_type | evsel->synth_sample_type);
 	perf_sample__exit(&sample);
 	return ret;
 }
-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v6 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[Ian Rogers]

An intel-pt trace can be turned into LBR events either in perf script
or perf inject with the --itrace=L option. With perf inject the
generated perf.data file failed to be parsed as the sample events were
out of sync with their perf_event_attr. A range of fixes were
required.

This patch was separated from a large perf script refactor that
highlighted the breakage:
https://lore.kernel.org/lkml/20260425224951.174663-1-irogers@google.com/

v6:
 - Address critical security and correctness feedback in Commit 2:
   * Fixed potential out-of-bounds read in perf_event__repipe_attr() by
     moving the header.size validation check before accessing
     event->attr.attr.size or copying.
   * Prevented 32-bit integer wrapping overflow on header.size validation
     by using subtraction instead of addition.
 - Restored PEBS LBR synthesis fixes in tools/perf/util/intel-pt.c.

v5:
 - Restored the missing PEBS branch stack synthesis fixes in intel-pt.c
   which were accidentally dropped in a previous rebase/conflict
   resolution.
 - Addressed the pipe mode size mismatch and ID array out-of-bounds read:
   * Safely copy the incoming attribute payload using min_t and
     memset zero, preventing trailing ID corruption.
   * Explicitly set the synthesized event's attr.size to match the tool's
     physical sizeof(struct perf_event_attr), guaranteeing perfect offset
     alignment and removing any risk of hallucinated/garbage IDs or
     underflow out-of-bounds reads.
 - Refactored both commit descriptions to strictly focus on code changes,
   deferring meta-commentary and implementation details exclusively to
   the cover letter.

v4:
 - Avoid temporary regressions in Commit 1:
   * Used local masked sample_type in convert_sample_callchain instead of
     unmasked evsel attribute, preventing heap overflows.
   * Promoted hardware tracer signature changes and dynamic retrieval of
     branch_sample_type to Commit 1, removing hardcoded 0 bugs.
   * Checked sample->evsel first before performing evlist__id2evsel lookup
     to optimize evsel retrieval when already populated.
 - Address critical security and correctness feedback in Commit 2:
   * Added check in perf_event__repipe_attr to prevent n_ids underflow.
   * Fixed early return error path in perf_event__repipe_sample to
     prevent state corruption and dangling pointers on dummy_bs.
   * Ensured perf_inject__cut_auxtrace_sample cuts the 8-byte size field
     even when aux_sample.size is 0 to prevent parser misalignment.
   * Expanded older attributes to PERF_ATTR_SIZE_VER2 in file mode
     within __cmd_inject to prevent silent truncation of
     branch_sample_type.
   * Added bounds checks against PERF_SAMPLE_MAX_SIZE to all hardware
     tracing synthetic helpers to prevent heap buffer overflows.
   * Fixed checkpatch.pl warnings/errors for line-wrapping.

v3:
 - Add missing Fixes: tags on both commits.
 - Refactor perf_event__repipe_attr to avoid in-place modifications on
   read-only mmap buffers, preventing SIGSEGV in file mode and premature
   evsel updates in pipe mode.
 - Use perf_event__synthesize_attr to correctly construct and repipe
   attributes in pipe mode.
 - Replace manual arithmetic in convert_sample_callchain with
   perf_event__sample_event_size to prevent uninitialized memory leaks.
 - Retrieve evsel branch_sample_type dynamically in util/arm-spe.c and
   util/cs-etm.c instead of hardcoding 0, resolving missing hw_idx field
   on synthesized branch stacks.

v2: Response to sashiko fixes for patch 2, Namhyung's acked-by for patch 1.

v1: https://lore.kernel.org/lkml/20260428070328.1880314-1-irogers@google.com/

Ian Rogers (2):
  perf event: Fix size of synthesized sample with branch stacks
  perf inject: Fix itrace branch stack synthesis

 tools/perf/bench/inject-buildid.c  |   9 +-
 tools/perf/builtin-inject.c        | 160 +++++++++++++++++++++++++----
 tools/perf/tests/dlfilter-test.c   |   8 +-
 tools/perf/tests/sample-parsing.c  |   5 +-
 tools/perf/util/arm-spe.c          |  28 ++++-
 tools/perf/util/cs-etm.c           |  28 ++++-
 tools/perf/util/intel-bts.c        |   3 +-
 tools/perf/util/intel-pt.c         |  32 ++++--
 tools/perf/util/synthetic-events.c |  25 +++--
 tools/perf/util/synthetic-events.h |   6 +-
 10 files changed, 254 insertions(+), 50 deletions(-)

-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v6 1/2] perf event: Fix size of synthesized sample with branch stacks

[Ian Rogers]

Synthesizing branch stacks for Intel-PT highlighted an issue where
PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the
perf_event_attr branch_sample_type. This caused an incorrect size
calculation.

Fix the writing of the nr and hw_idx values during sample event
synthesis by passing the branch_sample_type into the sample size
and synthesis functions. Also update hardware tracers (Intel PT,
ARM SPE, CS-ETM) to retrieve and pass their branch_sample_type
dynamically to prevent payload misalignment.

Fixes: d3f85437ad6a ("perf evsel: Support PERF_SAMPLE_BRANCH_HW_INDEX")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/bench/inject-buildid.c  |  9 ++++++---
 tools/perf/builtin-inject.c        | 12 +++++++++---
 tools/perf/tests/dlfilter-test.c   |  8 ++++++--
 tools/perf/tests/sample-parsing.c  |  5 +++--
 tools/perf/util/arm-spe.c          | 28 ++++++++++++++++++++++++----
 tools/perf/util/cs-etm.c           | 28 +++++++++++++++++++++++-----
 tools/perf/util/intel-bts.c        |  3 ++-
 tools/perf/util/intel-pt.c         | 27 +++++++++++++++++++++++----
 tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++-------
 tools/perf/util/synthetic-events.h |  6 ++++--
 10 files changed, 118 insertions(+), 33 deletions(-)

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7f..bfd2c5ec9488 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso,
 
 	event.header.type = PERF_RECORD_SAMPLE;
 	event.header.misc = PERF_RECORD_MISC_USER;
-	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
-
-	perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
+	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	perf_event__synthesize_sample(&event, bench_sample_type,
+				      /*read_format=*/0,
+				      /*branch_sample_type=*/0, &sample);
 
 	return writen(data->input_pipe[1], &event, event.header.size);
 }
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index a2493f1097df..2f20e782c7f2 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -465,8 +465,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	perf_event__synthesize_sample(event_copy, sample_type,
-				      evsel->core.attr.read_format, sample);
+	ret = perf_event__synthesize_sample(event_copy, sample_type,
+					    evsel->core.attr.read_format,
+					    evsel->core.attr.branch_sample_type, sample);
+	if (ret) {
+		pr_err("Failed to synthesize sample\n");
+		return ret;
+	}
 	return perf_event__repipe_synth(tool, event_copy);
 }
 
@@ -1102,7 +1107,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
 	sample_sw.period = sample->period;
 	sample_sw.time	 = sample->time;
 	perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
-				      evsel->core.attr.read_format, &sample_sw);
+				      evsel->core.attr.read_format,
+				      evsel->core.attr.branch_sample_type, &sample_sw);
 	build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
 	ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
 	perf_sample__exit(&sample_sw);
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index e63790c61d53..204663571943 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid
 
 	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.misc = PERF_RECORD_MISC_USER;
-	event->header.size = perf_event__sample_event_size(&sample, sample_type, 0);
-	err = perf_event__synthesize_sample(event, sample_type, 0, &sample);
+	event->header.size = perf_event__sample_event_size(&sample, sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	err = perf_event__synthesize_sample(event, sample_type,
+					    /*read_format=*/0,
+					    /*branch_sample_type=*/0, &sample);
 	if (err)
 		return test_result("perf_event__synthesize_sample() failed", TEST_FAIL);
 
diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
index a7327c942ca2..55f0b73ca20e 100644
--- a/tools/perf/tests/sample-parsing.c
+++ b/tools/perf/tests/sample-parsing.c
@@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 		sample.read.one.lost  = 1;
 	}
 
-	sz = perf_event__sample_event_size(&sample, sample_type, read_format);
+	sz = perf_event__sample_event_size(&sample, sample_type, read_format,
+					   evsel.core.attr.branch_sample_type);
 	bufsz = sz + 4096; /* Add a bit for overrun checking */
 	event = malloc(bufsz);
 	if (!event) {
@@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 	event->header.size = sz;
 
 	err = perf_event__synthesize_sample(event, sample_type, read_format,
-					    &sample);
+					    evsel.core.attr.branch_sample_type, &sample);
 	if (err) {
 		pr_debug("%s failed for sample_type %#"PRIx64", error %d\n",
 			 "perf_event__synthesize_sample", sample_type, err);
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 2b31da231ef3..31f05f467810 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -487,10 +487,30 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
 	bstack->hw_idx = -1ULL;
 }
 
-static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
+static int arm_spe__inject_event(struct arm_spe *spe, union perf_event *event,
+				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && spe->session && spe->session->evlist)
+		evsel = evlist__id2evsel(spe->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int
@@ -502,7 +522,7 @@ arm_spe_deliver_synth_event(struct arm_spe *spe,
 	int ret;
 
 	if (spe->synth_opts.inject) {
-		ret = arm_spe__inject_event(event, sample, spe->sample_type);
+		ret = arm_spe__inject_event(spe, event, sample, spe->sample_type);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 8a639d2e51a4..6ec48de29441 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1422,11 +1422,29 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
 		bs->nr += 1;
 }
 
-static int cs_etm__inject_event(union perf_event *event,
+static int cs_etm__inject_event(struct cs_etm_auxtrace *etm, union perf_event *event,
 			       struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && etm->session && etm->session->evlist)
+		evsel = evlist__id2evsel(etm->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 
@@ -1592,7 +1610,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
 		sample.branch_stack = tidq->last_branch;
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->instructions_sample_type);
 		if (ret)
 			return ret;
@@ -1667,7 +1685,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
 	}
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->branches_sample_type);
 		if (ret)
 			return ret;
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index 382255393fb3..0b18ebd13f7c 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq,
 		event.sample.header.size = bts->branches_event_size;
 		ret = perf_event__synthesize_sample(&event,
 						    bts->branches_sample_type,
-						    0, &sample);
+						    /*read_format=*/0, /*branch_sample_type=*/0,
+						    &sample);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index fc9eec8b54b8..dd2637678b40 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1728,11 +1728,30 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 	event->sample.header.misc = sample->cpumode;
 }
 
-static int intel_pt_inject_event(union perf_event *event,
+static int intel_pt_inject_event(struct intel_pt *pt, union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && pt->session && pt->session->evlist)
+		evsel = evlist__id2evsel(pt->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
@@ -1742,7 +1761,7 @@ static inline int intel_pt_opt_inject(struct intel_pt *pt,
 	if (!pt->synth_opts.inject)
 		return 0;
 
-	return intel_pt_inject_event(event, sample, type);
+	return intel_pt_inject_event(pt, event, sample, type);
 }
 
 static int intel_pt_deliver_synth_event(struct intel_pt *pt,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 85bee747f4cd..2461f25a4d7d 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool,
 	return process(tool, (union perf_event *) &event, NULL, machine);
 }
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format)
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format,
+				     u64 branch_sample_type)
 {
 	size_t sz, result = sizeof(struct perf_record_sample);
 
@@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
+		/* nr */
+		sz += sizeof(u64);
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)
+			sz += sizeof(u64);
 		result += sz;
 	}
 
@@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format,
 }
 
 int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
-				  const struct perf_sample *sample)
+				  u64 branch_sample_type, const struct perf_sample *sample)
 {
 	__u64 *array;
 	size_t sz;
@@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
-		memcpy(array, sample->branch_stack, sz);
+
+		*array++ = sample->branch_stack->nr;
+
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) {
+			if (sample->no_hw_idx)
+				*array++ = 0;
+			else
+				*array++ = sample->branch_stack->hw_idx;
+		}
+
+		memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz);
 		array = (void *)array + sz;
 	}
 
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index b0edad0c3100..8c7f49f9ccf5 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_
 int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
+int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
+				  u64 branch_sample_type, const struct perf_sample *sample);
 int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
 int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
@@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session,
 
 int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
+				     u64 read_format, u64 branch_sample_type);
 
 int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v6 2/2] perf inject: Fix itrace branch stack synthesis

[Ian Rogers]

When using "perf inject --itrace=L" to synthesize branch stacks from
AUX data, several issues caused failures with the generated file:

1. The synthesized samples were delivered without the
   PERF_SAMPLE_BRANCH_STACK flag if it was not in the original event's
   sample_type. Fixed by using sample_type | evsel->synth_sample_type
   in intel_pt_do_synth_pebs_sample.

2. Modifying evsel->core.attr.sample_type early in __cmd_inject caused
   parse failures for subsequent records in the input file. Fixed by
   moving this modification to just before writing the header.

3. perf_event__repipe_sample was narrowed to only synthesize samples
   when branch stack injection was requested, and restored the use of
   perf_inject__cut_auxtrace_sample as a fallback to preserve
   functionality.

4. Potential Heap Overflow in perf_event__repipe_sample: Addressed by
   adding a check that prints an error and returns -EFAULT if the
   calculated event size exceeds PERF_SAMPLE_MAX_SIZE.

5. Header vs Payload Mismatch in __cmd_inject: Addressed by narrowing
   the condition so that HEADER_BRANCH_STACK is only set in the file
   header if add_last_branch was true.

6. NULL Pointer Dereference in intel-pt.c: Addressed by updating the
   condition in intel_pt_do_synth_pebs_sample to fill sample.
   branch_stack if it warrants synthesis, even if not in the original
   sample_type.

7. Modifying event attributes in perf_event__repipe_attr in-place caused
   SIGSEGV on read-only mmap buffers in file mode and downstream parser
   breakage in pipe mode. Fixed by processing the unmodified attribute
   first, returning immediately in non-pipe mode, and correctly
   synthesizing a new attribute event for pipe output using
   perf_event__synthesize_attr. Also added a size validation check to
   prevent n_ids underflow when parsing header size.

8. Potential dangling pointer vulnerability in perf_event__repipe_sample:
   Addressed by restoring the original sample->branch_stack pointer
   before returning, including on early error return paths.

9. Off-by-one error in sample size check in perf_event__repipe_sample:
   Fixed by checking if sz >= PERF_SAMPLE_MAX_SIZE instead of >.

10. Unadvertised size field left in payload by cut_auxtrace_sample:
    Addressed by excluding the 8-byte size field from the copied
    payload to correctly match the cleared PERF_SAMPLE_AUX bit. Cut
    the AUX sample payload even if size is 0.

11. Inaccurate sample size calculation and uninitialized memory leaks in
    convert_sample_callchain: Fixed by replacing manual arithmetic with
    perf_event__sample_event_size and adding a bounds check against
    PERF_SAMPLE_MAX_SIZE.

12. Omission of branch_sample_type in file headers: Addressed by
    expanding older, smaller attributes to PERF_ATTR_SIZE_VER2 in
    __cmd_inject to ensure branch_sample_type is not silently omitted.

Fixes: 0f0aa5e0693c ("perf inject: Add Instruction Tracing support")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-inject.c | 148 ++++++++++++++++++++++++++++++++----
 tools/perf/util/intel-pt.c  |   5 +-
 2 files changed, 136 insertions(+), 17 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 2f20e782c7f2..29470d819442 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -216,12 +216,23 @@ static int perf_event__repipe_op4_synth(const struct perf_tool *tool,
 	return perf_event__repipe_synth(tool, event);
 }
 
+static int perf_event__repipe_synth_cb(const struct perf_tool *tool,
+				       union perf_event *event,
+				       struct perf_sample *sample __maybe_unused,
+				       struct machine *machine __maybe_unused)
+{
+	return perf_event__repipe_synth(tool, event);
+}
+
 static int perf_event__repipe_attr(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct evlist **pevlist)
 {
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
 						  tool);
+	struct perf_event_attr attr;
+	size_t n_ids;
+	u64 *ids;
 	int ret;
 
 	ret = perf_event__process_attr(tool, event, pevlist);
@@ -232,7 +243,37 @@ static int perf_event__repipe_attr(const struct perf_tool *tool,
 	if (!inject->output.is_pipe)
 		return 0;
 
-	return perf_event__repipe_synth(tool, event);
+	if (!inject->itrace_synth_opts.set)
+		return perf_event__repipe_synth(tool, event);
+
+	if (event->header.size < sizeof(struct perf_event_header) + sizeof(u64)) {
+		pr_err("Attribute event size %u is too small\n", event->header.size);
+		return -EINVAL;
+	}
+
+	if (event->header.size - sizeof(event->header) < event->attr.attr.size) {
+		pr_err("Attribute event size %u is too small for attr.size %u\n",
+		       event->header.size, event->attr.attr.size);
+		return -EINVAL;
+	}
+
+	memset(&attr, 0, sizeof(attr));
+	memcpy(&attr, &event->attr.attr,
+	       min_t(size_t, sizeof(attr), (size_t)event->attr.attr.size));
+
+	n_ids = event->header.size - sizeof(event->header) - event->attr.attr.size;
+	n_ids /= sizeof(u64);
+	ids = perf_record_header_attr_id(event);
+
+	attr.size = sizeof(struct perf_event_attr);
+	attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+	if (inject->itrace_synth_opts.add_last_branch) {
+		attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+		attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+	}
+	return perf_event__synthesize_attr(tool, &attr, (u32)n_ids, ids,
+					   perf_event__repipe_synth_cb);
 }
 
 static int perf_event__repipe_event_update(const struct perf_tool *tool,
@@ -331,8 +372,8 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 				 union perf_event *event,
 				 struct perf_sample *sample)
 {
-	size_t sz1 = sample->aux_sample.data - (void *)event;
-	size_t sz2 = event->header.size - sample->aux_sample.size - sz1;
+	size_t sz1 = sample->aux_sample.data - (void *)event - sizeof(u64);
+	size_t sz2 = event->header.size - sample->aux_sample.size - (sz1 + sizeof(u64));
 	union perf_event *ev;
 
 	if (inject->event_copy == NULL) {
@@ -343,13 +384,12 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 	ev = (union perf_event *)inject->event_copy;
 	if (sz1 > event->header.size || sz2 > event->header.size ||
 	    sz1 + sz2 > event->header.size ||
-	    sz1 < sizeof(struct perf_event_header) + sizeof(u64))
+	    sz1 < sizeof(struct perf_event_header))
 		return event;
 
 	memcpy(ev, event, sz1);
 	memcpy((void *)ev + sz1, (void *)event + event->header.size - sz2, sz2);
 	ev->header.size = sz1 + sz2;
-	((u64 *)((void *)ev + sz1))[-1] = 0;
 
 	return ev;
 }
@@ -376,7 +416,67 @@ static int perf_event__repipe_sample(const struct perf_tool *tool,
 
 	build_id__mark_dso_hit(tool, event, sample, evsel, machine);
 
-	if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
+	if (inject->itrace_synth_opts.set &&
+	    (inject->itrace_synth_opts.last_branch ||
+	     inject->itrace_synth_opts.add_last_branch)) {
+		union perf_event *event_copy = (void *)inject->event_copy;
+		struct branch_stack dummy_bs = { .nr = 0, .hw_idx = 0 };
+		int err;
+		size_t sz;
+		u64 orig_type = evsel->core.attr.sample_type;
+		u64 orig_branch_type = evsel->core.attr.branch_sample_type;
+
+		struct branch_stack *orig_bs = sample->branch_stack;
+
+		if (event_copy == NULL) {
+			inject->event_copy = malloc(PERF_SAMPLE_MAX_SIZE);
+			if (!inject->event_copy)
+				return -ENOMEM;
+
+			event_copy = (void *)inject->event_copy;
+		}
+
+		if (!sample->branch_stack)
+			sample->branch_stack = &dummy_bs;
+
+		if (inject->itrace_synth_opts.add_last_branch) {
+			/* Temporarily add in type bits for synthesis. */
+			evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+			evsel->core.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+		}
+		evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+		sz = perf_event__sample_event_size(sample, evsel->core.attr.sample_type,
+						   evsel->core.attr.read_format,
+						   evsel->core.attr.branch_sample_type);
+
+		if (sz >= PERF_SAMPLE_MAX_SIZE) {
+			pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+			evsel->core.attr.sample_type = orig_type;
+			evsel->core.attr.branch_sample_type = orig_branch_type;
+			sample->branch_stack = orig_bs;
+			return -EFAULT;
+		}
+
+		event_copy->header.type = PERF_RECORD_SAMPLE;
+		event_copy->header.misc = event->header.misc;
+		event_copy->header.size = sz;
+
+		err = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+						    evsel->core.attr.read_format,
+						    evsel->core.attr.branch_sample_type, sample);
+
+		evsel->core.attr.sample_type = orig_type;
+		evsel->core.attr.branch_sample_type = orig_branch_type;
+		sample->branch_stack = orig_bs;
+
+		if (err) {
+			pr_err("Failed to synthesize sample\n");
+			return err;
+		}
+		event = event_copy;
+	} else if (inject->itrace_synth_opts.set &&
+		   (evsel->core.attr.sample_type & PERF_SAMPLE_AUX)) {
 		event = perf_inject__cut_auxtrace_sample(inject, event, sample);
 		if (IS_ERR(event))
 			return PTR_ERR(event);
@@ -397,7 +497,7 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	struct callchain_cursor_node *node;
 	struct thread *thread;
 	u64 sample_type = evsel->core.attr.sample_type;
-	u32 sample_size = event->header.size;
+	size_t sz;
 	u64 i, k;
 	int ret;
 
@@ -456,15 +556,18 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 out:
 	memcpy(event_copy, event, sizeof(event->header));
 
-	/* adjust sample size for stack and regs */
-	sample_size -= sample->user_stack.size;
-	sample_size -= (hweight64(evsel->core.attr.sample_regs_user) + 1) * sizeof(u64);
-	sample_size += (sample->callchain->nr + 1) * sizeof(u64);
-	event_copy->header.size = sample_size;
-
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
+	sz = perf_event__sample_event_size(sample, sample_type,
+					   evsel->core.attr.read_format,
+					   evsel->core.attr.branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event_copy->header.size = sz;
+
 	ret = perf_event__synthesize_sample(event_copy, sample_type,
 					    evsel->core.attr.read_format,
 					    evsel->core.attr.branch_sample_type, sample);
@@ -2442,12 +2545,27 @@ static int __cmd_inject(struct perf_inject *inject)
 		 * synthesized hardware events, so clear the feature flag.
 		 */
 		if (inject->itrace_synth_opts.set) {
+			struct evsel *evsel;
+
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
-			if (inject->itrace_synth_opts.last_branch ||
-			    inject->itrace_synth_opts.add_last_branch)
+
+			evlist__for_each_entry(session->evlist, evsel) {
+				evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+			}
+
+			if (inject->itrace_synth_opts.add_last_branch) {
 				perf_header__set_feat(&session->header,
 						      HEADER_BRANCH_STACK);
+
+				evlist__for_each_entry(session->evlist, evsel) {
+					evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+					if (evsel->core.attr.size < PERF_ATTR_SIZE_VER2)
+						evsel->core.attr.size = PERF_ATTR_SIZE_VER2;
+					evsel->core.attr.branch_sample_type |=
+						PERF_SAMPLE_BRANCH_HW_INDEX;
+				}
+			}
 		}
 
 		/*
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index dd2637678b40..7153b48cfe63 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -2505,7 +2505,7 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		intel_pt_add_xmm(intr_regs, pos, items, regs_mask);
 	}
 
-	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+	if ((sample_type | evsel->synth_sample_type) & PERF_SAMPLE_BRANCH_STACK) {
 		if (items->mask[INTEL_PT_LBR_0_POS] ||
 		    items->mask[INTEL_PT_LBR_1_POS] ||
 		    items->mask[INTEL_PT_LBR_2_POS]) {
@@ -2576,7 +2576,8 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		sample.transaction = txn;
 	}
 
-	ret = intel_pt_deliver_synth_event(pt, event, &sample, sample_type);
+	ret = intel_pt_deliver_synth_event(pt, event, &sample,
+					   sample_type | evsel->synth_sample_type);
 	perf_sample__exit(&sample);
 	return ret;
 }
-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v7 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[Ian Rogers]

An intel-pt trace can be turned into LBR events either in perf script
or perf inject with the --itrace=L option. With perf inject the
generated perf.data file failed to be parsed as the sample events were
out of sync with their perf_event_attr. A range of fixes were
required.

This patch was separated from a large perf script refactor that
highlighted the breakage:
https://lore.kernel.org/lkml/20260425224951.174663-1-irogers@google.com/

v7:
 - Fixed a critical NULL pointer dereference crash in Commit 2:
   * In tools/perf/util/intel-pt.c, when branch stack injection is
     requested (add_last_branch is true) but last_branch is false (such
     as in perf inject --itrace=L), ptq->last_branch was not allocated.
   * When PEBS branch stack synthesis is forced via
     evsel->synth_sample_type, the code dereferenced ptq->last_branch
     inside do_synth_pebs_sample (either in intel_pt_add_lbrs or by
     setting nr = 0), causing a SEGSEGV.
   * Fixed by ensuring ptq->last_branch is successfully allocated in
     intel_pt_alloc_queue() when add_last_branch is requested.

v6:
 - Address critical security and correctness feedback in Commit 2:
   * Fixed potential out-of-bounds read in perf_event__repipe_attr() by
     moving the header.size validation check before accessing
     event->attr.attr.size or copying.
   * Prevented 32-bit integer wrapping overflow on header.size validation
     by using subtraction instead of addition.
 - Restored PEBS LBR synthesis fixes in tools/perf/util/intel-pt.c.

v5:
 - Restored the missing PEBS branch stack synthesis fixes in intel-pt.c
   which were accidentally dropped in a previous rebase/conflict
   resolution.
 - Addressed the pipe mode size mismatch and ID array out-of-bounds read:
   * Safely copy the incoming attribute payload using min_t and
     memset zero, preventing trailing ID corruption.
   * Explicitly set the synthesized event's attr.size to match the tool's
     physical sizeof(struct perf_event_attr), guaranteeing perfect offset
     alignment and removing any risk of hallucinated/garbage IDs or
     underflow out-of-bounds reads.
 - Refactored both commit descriptions to strictly focus on code changes,
   deferring meta-commentary and implementation details exclusively to
   the cover letter.

v4:
 - Avoid temporary regressions in Commit 1:
   * Used local masked sample_type in convert_sample_callchain instead of
     unmasked evsel attribute, preventing heap overflows.
   * Promoted hardware tracer signature changes and dynamic retrieval of
     branch_sample_type to Commit 1, removing hardcoded 0 bugs.
   * Checked sample->evsel first before performing evlist__id2evsel lookup
     to optimize evsel retrieval when already populated.
 - Address critical security and correctness feedback in Commit 2:
   * Added check in perf_event__repipe_attr to prevent n_ids underflow.
   * Fixed early return error path in perf_event__repipe_sample to
     prevent state corruption and dangling pointers on dummy_bs.
   * Ensured perf_inject__cut_auxtrace_sample cuts the 8-byte size field
     even when aux_sample.size is 0 to prevent parser misalignment.
   * Expanded older attributes to PERF_ATTR_SIZE_VER2 in file mode
     within __cmd_inject to prevent silent truncation of
     branch_sample_type.
   * Added bounds checks against PERF_SAMPLE_MAX_SIZE to all hardware
     tracing synthetic helpers to prevent heap buffer overflows.
   * Fixed checkpatch.pl warnings/errors for line-wrapping.

v3:
 - Add missing Fixes: tags on both commits.
 - Refactor perf_event__repipe_attr to avoid in-place modifications on
   read-only mmap buffers, preventing SIGSEGV in file mode and premature
   evsel updates in pipe mode.
 - Use perf_event__synthesize_attr to correctly construct and repipe
   attributes in pipe mode.
 - Replace manual arithmetic in convert_sample_callchain with
   perf_event__sample_event_size to prevent uninitialized memory leaks.
 - Retrieve evsel branch_sample_type dynamically in util/arm-spe.c and
   util/cs-etm.c instead of hardcoding 0, resolving missing hw_idx field
   on synthesized branch stacks.

v2: Response to sashiko fixes for patch 2, Namhyung's acked-by for patch 1.

v1: https://lore.kernel.org/lkml/20260428070328.1880314-1-irogers@google.com/

Ian Rogers (2):
  perf event: Fix size of synthesized sample with branch stacks
  perf inject: Fix itrace branch stack synthesis

 tools/perf/bench/inject-buildid.c  |   9 +-
 tools/perf/builtin-inject.c        | 160 +++++++++++++++++++++++++----
 tools/perf/tests/dlfilter-test.c   |   8 +-
 tools/perf/tests/sample-parsing.c  |   5 +-
 tools/perf/util/arm-spe.c          |  28 ++++-
 tools/perf/util/cs-etm.c           |  28 ++++-
 tools/perf/util/intel-bts.c        |   3 +-
 tools/perf/util/intel-pt.c         |  35 +++++--
 tools/perf/util/synthetic-events.c |  25 +++--
 tools/perf/util/synthetic-events.h |   6 +-
 10 files changed, 256 insertions(+), 51 deletions(-)

-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v7 1/2] perf event: Fix size of synthesized sample with branch stacks

[Ian Rogers]

Synthesizing branch stacks for Intel-PT highlighted an issue where
PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the
perf_event_attr branch_sample_type. This caused an incorrect size
calculation.

Fix the writing of the nr and hw_idx values during sample event
synthesis by passing the branch_sample_type into the sample size
and synthesis functions. Also update hardware tracers (Intel PT,
ARM SPE, CS-ETM) to retrieve and pass their branch_sample_type
dynamically to prevent payload misalignment.

Fixes: d3f85437ad6a ("perf evsel: Support PERF_SAMPLE_BRANCH_HW_INDEX")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/bench/inject-buildid.c  |  9 ++++++---
 tools/perf/builtin-inject.c        | 12 +++++++++---
 tools/perf/tests/dlfilter-test.c   |  8 ++++++--
 tools/perf/tests/sample-parsing.c  |  5 +++--
 tools/perf/util/arm-spe.c          | 28 ++++++++++++++++++++++++----
 tools/perf/util/cs-etm.c           | 28 +++++++++++++++++++++++-----
 tools/perf/util/intel-bts.c        |  3 ++-
 tools/perf/util/intel-pt.c         | 27 +++++++++++++++++++++++----
 tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++-------
 tools/perf/util/synthetic-events.h |  6 ++++--
 10 files changed, 118 insertions(+), 33 deletions(-)

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7f..bfd2c5ec9488 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso,
 
 	event.header.type = PERF_RECORD_SAMPLE;
 	event.header.misc = PERF_RECORD_MISC_USER;
-	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
-
-	perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
+	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	perf_event__synthesize_sample(&event, bench_sample_type,
+				      /*read_format=*/0,
+				      /*branch_sample_type=*/0, &sample);
 
 	return writen(data->input_pipe[1], &event, event.header.size);
 }
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index a2493f1097df..2f20e782c7f2 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -465,8 +465,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	perf_event__synthesize_sample(event_copy, sample_type,
-				      evsel->core.attr.read_format, sample);
+	ret = perf_event__synthesize_sample(event_copy, sample_type,
+					    evsel->core.attr.read_format,
+					    evsel->core.attr.branch_sample_type, sample);
+	if (ret) {
+		pr_err("Failed to synthesize sample\n");
+		return ret;
+	}
 	return perf_event__repipe_synth(tool, event_copy);
 }
 
@@ -1102,7 +1107,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
 	sample_sw.period = sample->period;
 	sample_sw.time	 = sample->time;
 	perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
-				      evsel->core.attr.read_format, &sample_sw);
+				      evsel->core.attr.read_format,
+				      evsel->core.attr.branch_sample_type, &sample_sw);
 	build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
 	ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
 	perf_sample__exit(&sample_sw);
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index e63790c61d53..204663571943 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid
 
 	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.misc = PERF_RECORD_MISC_USER;
-	event->header.size = perf_event__sample_event_size(&sample, sample_type, 0);
-	err = perf_event__synthesize_sample(event, sample_type, 0, &sample);
+	event->header.size = perf_event__sample_event_size(&sample, sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	err = perf_event__synthesize_sample(event, sample_type,
+					    /*read_format=*/0,
+					    /*branch_sample_type=*/0, &sample);
 	if (err)
 		return test_result("perf_event__synthesize_sample() failed", TEST_FAIL);
 
diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
index a7327c942ca2..55f0b73ca20e 100644
--- a/tools/perf/tests/sample-parsing.c
+++ b/tools/perf/tests/sample-parsing.c
@@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 		sample.read.one.lost  = 1;
 	}
 
-	sz = perf_event__sample_event_size(&sample, sample_type, read_format);
+	sz = perf_event__sample_event_size(&sample, sample_type, read_format,
+					   evsel.core.attr.branch_sample_type);
 	bufsz = sz + 4096; /* Add a bit for overrun checking */
 	event = malloc(bufsz);
 	if (!event) {
@@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 	event->header.size = sz;
 
 	err = perf_event__synthesize_sample(event, sample_type, read_format,
-					    &sample);
+					    evsel.core.attr.branch_sample_type, &sample);
 	if (err) {
 		pr_debug("%s failed for sample_type %#"PRIx64", error %d\n",
 			 "perf_event__synthesize_sample", sample_type, err);
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 2b31da231ef3..31f05f467810 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -487,10 +487,30 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
 	bstack->hw_idx = -1ULL;
 }
 
-static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
+static int arm_spe__inject_event(struct arm_spe *spe, union perf_event *event,
+				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && spe->session && spe->session->evlist)
+		evsel = evlist__id2evsel(spe->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int
@@ -502,7 +522,7 @@ arm_spe_deliver_synth_event(struct arm_spe *spe,
 	int ret;
 
 	if (spe->synth_opts.inject) {
-		ret = arm_spe__inject_event(event, sample, spe->sample_type);
+		ret = arm_spe__inject_event(spe, event, sample, spe->sample_type);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 8a639d2e51a4..6ec48de29441 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1422,11 +1422,29 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
 		bs->nr += 1;
 }
 
-static int cs_etm__inject_event(union perf_event *event,
+static int cs_etm__inject_event(struct cs_etm_auxtrace *etm, union perf_event *event,
 			       struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && etm->session && etm->session->evlist)
+		evsel = evlist__id2evsel(etm->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 
@@ -1592,7 +1610,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
 		sample.branch_stack = tidq->last_branch;
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->instructions_sample_type);
 		if (ret)
 			return ret;
@@ -1667,7 +1685,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
 	}
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->branches_sample_type);
 		if (ret)
 			return ret;
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index 382255393fb3..0b18ebd13f7c 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq,
 		event.sample.header.size = bts->branches_event_size;
 		ret = perf_event__synthesize_sample(&event,
 						    bts->branches_sample_type,
-						    0, &sample);
+						    /*read_format=*/0, /*branch_sample_type=*/0,
+						    &sample);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index fc9eec8b54b8..dd2637678b40 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1728,11 +1728,30 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 	event->sample.header.misc = sample->cpumode;
 }
 
-static int intel_pt_inject_event(union perf_event *event,
+static int intel_pt_inject_event(struct intel_pt *pt, union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && pt->session && pt->session->evlist)
+		evsel = evlist__id2evsel(pt->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
@@ -1742,7 +1761,7 @@ static inline int intel_pt_opt_inject(struct intel_pt *pt,
 	if (!pt->synth_opts.inject)
 		return 0;
 
-	return intel_pt_inject_event(event, sample, type);
+	return intel_pt_inject_event(pt, event, sample, type);
 }
 
 static int intel_pt_deliver_synth_event(struct intel_pt *pt,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 85bee747f4cd..2461f25a4d7d 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool,
 	return process(tool, (union perf_event *) &event, NULL, machine);
 }
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format)
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format,
+				     u64 branch_sample_type)
 {
 	size_t sz, result = sizeof(struct perf_record_sample);
 
@@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
+		/* nr */
+		sz += sizeof(u64);
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)
+			sz += sizeof(u64);
 		result += sz;
 	}
 
@@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format,
 }
 
 int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
-				  const struct perf_sample *sample)
+				  u64 branch_sample_type, const struct perf_sample *sample)
 {
 	__u64 *array;
 	size_t sz;
@@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
-		memcpy(array, sample->branch_stack, sz);
+
+		*array++ = sample->branch_stack->nr;
+
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) {
+			if (sample->no_hw_idx)
+				*array++ = 0;
+			else
+				*array++ = sample->branch_stack->hw_idx;
+		}
+
+		memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz);
 		array = (void *)array + sz;
 	}
 
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index b0edad0c3100..8c7f49f9ccf5 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_
 int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
+int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
+				  u64 branch_sample_type, const struct perf_sample *sample);
 int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
 int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
@@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session,
 
 int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
+				     u64 read_format, u64 branch_sample_type);
 
 int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v7 2/2] perf inject: Fix itrace branch stack synthesis

[Ian Rogers]

When using "perf inject --itrace=L" to synthesize branch stacks from
AUX data, several issues caused failures with the generated file:

1. The synthesized samples were delivered without the
   PERF_SAMPLE_BRANCH_STACK flag if it was not in the original event's
   sample_type. Fixed by using sample_type | evsel->synth_sample_type
   in intel_pt_do_synth_pebs_sample.

2. Modifying evsel->core.attr.sample_type early in __cmd_inject caused
   parse failures for subsequent records in the input file. Fixed by
   moving this modification to just before writing the header.

3. perf_event__repipe_sample was narrowed to only synthesize samples
   when branch stack injection was requested, and restored the use of
   perf_inject__cut_auxtrace_sample as a fallback to preserve
   functionality.

4. Potential Heap Overflow in perf_event__repipe_sample: Addressed by
   adding a check that prints an error and returns -EFAULT if the
   calculated event size exceeds PERF_SAMPLE_MAX_SIZE.

5. Header vs Payload Mismatch in __cmd_inject: Addressed by narrowing
   the condition so that HEADER_BRANCH_STACK is only set in the file
   header if add_last_branch was true.

6. NULL Pointer Dereference in intel-pt.c: When branch stack injection
   is requested (add_last_branch is true) but last_branch is false
   (e.g., perf inject --itrace=L), ptq->last_branch was not allocated.
   However, PEBS branch stack synthesis (via synth_sample_type) still
   forced LBR handling in do_synth_pebs_sample(), dereferencing the
   NULL ptq->last_branch pointer. Guarding the dereference is not
   sufficient because downstream sample size calculation and synthesis
   strictly require a non-NULL branch_stack when the bit is set.
   Fixed by ensuring ptq->last_branch is allocated in
   intel_pt_alloc_queue() when add_last_branch is requested.

7. Modifying event attributes in perf_event__repipe_attr in-place caused
   SIGSEGV on read-only mmap buffers in file mode and downstream parser
   breakage in pipe mode. Fixed by processing the unmodified attribute
   first, returning immediately in non-pipe mode, and correctly
   synthesizing a new attribute event for pipe output using
   perf_event__synthesize_attr. Also:
   - Added a size validation check and integer underflow protection when
     parsing n_ids.
   - Prevented Trailing ID memory corruption by zero-initializing the
     local attr copy and safely copying using min_t(size_t, sizeof(attr),
     event->attr.attr.size).
   - Resolved ID array parsing mismatch downstream by expanding attr.size to
     sizeof(struct perf_event_attr) before synthesis to guarantee perfect
     header/attribute size alignment.

8. Potential dangling pointer vulnerability in perf_event__repipe_sample:
   Addressed by restoring the original sample->branch_stack pointer
   before returning, including on early error return paths.

9. Off-by-one error in sample size check in perf_event__repipe_sample:
   Fixed by checking if sz >= PERF_SAMPLE_MAX_SIZE instead of >.

10. Unadvertised size field left in payload by cut_auxtrace_sample:
    Addressed by excluding the 8-byte size field from the copied
    payload to correctly match the cleared PERF_SAMPLE_AUX bit. Cut
    the AUX sample payload even if size is 0.

11. Inaccurate sample size calculation and uninitialized memory leaks in
    convert_sample_callchain: Fixed by replacing manual arithmetic with
    perf_event__sample_event_size and adding a bounds check against
    PERF_SAMPLE_MAX_SIZE.

12. Omission of branch_sample_type in file headers: Addressed by
    expanding older, smaller attributes to PERF_ATTR_SIZE_VER2 in
    __cmd_inject to ensure branch_sample_type is not silently omitted.

Fixes: 0f0aa5e0693c ("perf inject: Add Instruction Tracing support")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-inject.c | 148 ++++++++++++++++++++++++++++++++----
 tools/perf/util/intel-pt.c  |   8 +-
 2 files changed, 138 insertions(+), 18 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 2f20e782c7f2..29470d819442 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -216,12 +216,23 @@ static int perf_event__repipe_op4_synth(const struct perf_tool *tool,
 	return perf_event__repipe_synth(tool, event);
 }
 
+static int perf_event__repipe_synth_cb(const struct perf_tool *tool,
+				       union perf_event *event,
+				       struct perf_sample *sample __maybe_unused,
+				       struct machine *machine __maybe_unused)
+{
+	return perf_event__repipe_synth(tool, event);
+}
+
 static int perf_event__repipe_attr(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct evlist **pevlist)
 {
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
 						  tool);
+	struct perf_event_attr attr;
+	size_t n_ids;
+	u64 *ids;
 	int ret;
 
 	ret = perf_event__process_attr(tool, event, pevlist);
@@ -232,7 +243,37 @@ static int perf_event__repipe_attr(const struct perf_tool *tool,
 	if (!inject->output.is_pipe)
 		return 0;
 
-	return perf_event__repipe_synth(tool, event);
+	if (!inject->itrace_synth_opts.set)
+		return perf_event__repipe_synth(tool, event);
+
+	if (event->header.size < sizeof(struct perf_event_header) + sizeof(u64)) {
+		pr_err("Attribute event size %u is too small\n", event->header.size);
+		return -EINVAL;
+	}
+
+	if (event->header.size - sizeof(event->header) < event->attr.attr.size) {
+		pr_err("Attribute event size %u is too small for attr.size %u\n",
+		       event->header.size, event->attr.attr.size);
+		return -EINVAL;
+	}
+
+	memset(&attr, 0, sizeof(attr));
+	memcpy(&attr, &event->attr.attr,
+	       min_t(size_t, sizeof(attr), (size_t)event->attr.attr.size));
+
+	n_ids = event->header.size - sizeof(event->header) - event->attr.attr.size;
+	n_ids /= sizeof(u64);
+	ids = perf_record_header_attr_id(event);
+
+	attr.size = sizeof(struct perf_event_attr);
+	attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+	if (inject->itrace_synth_opts.add_last_branch) {
+		attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+		attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+	}
+	return perf_event__synthesize_attr(tool, &attr, (u32)n_ids, ids,
+					   perf_event__repipe_synth_cb);
 }
 
 static int perf_event__repipe_event_update(const struct perf_tool *tool,
@@ -331,8 +372,8 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 				 union perf_event *event,
 				 struct perf_sample *sample)
 {
-	size_t sz1 = sample->aux_sample.data - (void *)event;
-	size_t sz2 = event->header.size - sample->aux_sample.size - sz1;
+	size_t sz1 = sample->aux_sample.data - (void *)event - sizeof(u64);
+	size_t sz2 = event->header.size - sample->aux_sample.size - (sz1 + sizeof(u64));
 	union perf_event *ev;
 
 	if (inject->event_copy == NULL) {
@@ -343,13 +384,12 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 	ev = (union perf_event *)inject->event_copy;
 	if (sz1 > event->header.size || sz2 > event->header.size ||
 	    sz1 + sz2 > event->header.size ||
-	    sz1 < sizeof(struct perf_event_header) + sizeof(u64))
+	    sz1 < sizeof(struct perf_event_header))
 		return event;
 
 	memcpy(ev, event, sz1);
 	memcpy((void *)ev + sz1, (void *)event + event->header.size - sz2, sz2);
 	ev->header.size = sz1 + sz2;
-	((u64 *)((void *)ev + sz1))[-1] = 0;
 
 	return ev;
 }
@@ -376,7 +416,67 @@ static int perf_event__repipe_sample(const struct perf_tool *tool,
 
 	build_id__mark_dso_hit(tool, event, sample, evsel, machine);
 
-	if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
+	if (inject->itrace_synth_opts.set &&
+	    (inject->itrace_synth_opts.last_branch ||
+	     inject->itrace_synth_opts.add_last_branch)) {
+		union perf_event *event_copy = (void *)inject->event_copy;
+		struct branch_stack dummy_bs = { .nr = 0, .hw_idx = 0 };
+		int err;
+		size_t sz;
+		u64 orig_type = evsel->core.attr.sample_type;
+		u64 orig_branch_type = evsel->core.attr.branch_sample_type;
+
+		struct branch_stack *orig_bs = sample->branch_stack;
+
+		if (event_copy == NULL) {
+			inject->event_copy = malloc(PERF_SAMPLE_MAX_SIZE);
+			if (!inject->event_copy)
+				return -ENOMEM;
+
+			event_copy = (void *)inject->event_copy;
+		}
+
+		if (!sample->branch_stack)
+			sample->branch_stack = &dummy_bs;
+
+		if (inject->itrace_synth_opts.add_last_branch) {
+			/* Temporarily add in type bits for synthesis. */
+			evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+			evsel->core.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+		}
+		evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+		sz = perf_event__sample_event_size(sample, evsel->core.attr.sample_type,
+						   evsel->core.attr.read_format,
+						   evsel->core.attr.branch_sample_type);
+
+		if (sz >= PERF_SAMPLE_MAX_SIZE) {
+			pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+			evsel->core.attr.sample_type = orig_type;
+			evsel->core.attr.branch_sample_type = orig_branch_type;
+			sample->branch_stack = orig_bs;
+			return -EFAULT;
+		}
+
+		event_copy->header.type = PERF_RECORD_SAMPLE;
+		event_copy->header.misc = event->header.misc;
+		event_copy->header.size = sz;
+
+		err = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+						    evsel->core.attr.read_format,
+						    evsel->core.attr.branch_sample_type, sample);
+
+		evsel->core.attr.sample_type = orig_type;
+		evsel->core.attr.branch_sample_type = orig_branch_type;
+		sample->branch_stack = orig_bs;
+
+		if (err) {
+			pr_err("Failed to synthesize sample\n");
+			return err;
+		}
+		event = event_copy;
+	} else if (inject->itrace_synth_opts.set &&
+		   (evsel->core.attr.sample_type & PERF_SAMPLE_AUX)) {
 		event = perf_inject__cut_auxtrace_sample(inject, event, sample);
 		if (IS_ERR(event))
 			return PTR_ERR(event);
@@ -397,7 +497,7 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	struct callchain_cursor_node *node;
 	struct thread *thread;
 	u64 sample_type = evsel->core.attr.sample_type;
-	u32 sample_size = event->header.size;
+	size_t sz;
 	u64 i, k;
 	int ret;
 
@@ -456,15 +556,18 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 out:
 	memcpy(event_copy, event, sizeof(event->header));
 
-	/* adjust sample size for stack and regs */
-	sample_size -= sample->user_stack.size;
-	sample_size -= (hweight64(evsel->core.attr.sample_regs_user) + 1) * sizeof(u64);
-	sample_size += (sample->callchain->nr + 1) * sizeof(u64);
-	event_copy->header.size = sample_size;
-
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
+	sz = perf_event__sample_event_size(sample, sample_type,
+					   evsel->core.attr.read_format,
+					   evsel->core.attr.branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event_copy->header.size = sz;
+
 	ret = perf_event__synthesize_sample(event_copy, sample_type,
 					    evsel->core.attr.read_format,
 					    evsel->core.attr.branch_sample_type, sample);
@@ -2442,12 +2545,27 @@ static int __cmd_inject(struct perf_inject *inject)
 		 * synthesized hardware events, so clear the feature flag.
 		 */
 		if (inject->itrace_synth_opts.set) {
+			struct evsel *evsel;
+
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
-			if (inject->itrace_synth_opts.last_branch ||
-			    inject->itrace_synth_opts.add_last_branch)
+
+			evlist__for_each_entry(session->evlist, evsel) {
+				evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+			}
+
+			if (inject->itrace_synth_opts.add_last_branch) {
 				perf_header__set_feat(&session->header,
 						      HEADER_BRANCH_STACK);
+
+				evlist__for_each_entry(session->evlist, evsel) {
+					evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+					if (evsel->core.attr.size < PERF_ATTR_SIZE_VER2)
+						evsel->core.attr.size = PERF_ATTR_SIZE_VER2;
+					evsel->core.attr.branch_sample_type |=
+						PERF_SAMPLE_BRANCH_HW_INDEX;
+				}
+			}
 		}
 
 		/*
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index dd2637678b40..d9c86ac49748 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1307,7 +1307,8 @@ static struct intel_pt_queue *intel_pt_alloc_queue(struct intel_pt *pt,
 			goto out_free;
 	}
 
-	if (pt->synth_opts.last_branch || pt->synth_opts.other_events) {
+	if (pt->synth_opts.last_branch || pt->synth_opts.add_last_branch ||
+	    pt->synth_opts.other_events) {
 		unsigned int entry_cnt = max(LBRS_MAX, pt->br_stack_sz);
 
 		ptq->last_branch = intel_pt_alloc_br_stack(entry_cnt);
@@ -2505,7 +2506,7 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		intel_pt_add_xmm(intr_regs, pos, items, regs_mask);
 	}
 
-	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+	if ((sample_type | evsel->synth_sample_type) & PERF_SAMPLE_BRANCH_STACK) {
 		if (items->mask[INTEL_PT_LBR_0_POS] ||
 		    items->mask[INTEL_PT_LBR_1_POS] ||
 		    items->mask[INTEL_PT_LBR_2_POS]) {
@@ -2576,7 +2577,8 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		sample.transaction = txn;
 	}
 
-	ret = intel_pt_deliver_synth_event(pt, event, &sample, sample_type);
+	ret = intel_pt_deliver_synth_event(pt, event, &sample,
+					   sample_type | evsel->synth_sample_type);
 	perf_sample__exit(&sample);
 	return ret;
 }
-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v8 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[Ian Rogers]

An intel-pt trace can be turned into LBR events either in perf script
or perf inject with the --itrace=L option. With perf inject the
generated perf.data file failed to be parsed as the sample events were
out of sync with their perf_event_attr. A range of fixes were
required.

This patch was separated from a large perf script refactor that
highlighted the breakage:
https://lore.kernel.org/lkml/20260425224951.174663-1-irogers@google.com/

v8:
 - Avoid potential NULL pointer dereference of evsel in Commit 2:
   * If machines__deliver_event() processes a malformed PERF_RECORD_READ
     event with an unknown or missing sample ID, the evsel is passed
     as NULL.
   * Added an early evsel == NULL check in perf_event__repipe_sample()
     to safely fallback and repipe the raw event unmodified, preventing
     any segmentation faults.

v7:
 - Fixed a critical NULL pointer dereference crash in Commit 2:
   * In tools/perf/util/intel-pt.c, when branch stack injection is
     requested (add_last_branch is true) but last_branch is false (such
     as in perf inject --itrace=L), ptq->last_branch was not allocated.
   * When PEBS branch stack synthesis is forced via
     evsel->synth_sample_type, the code dereferenced ptq->last_branch
     inside do_synth_pebs_sample (either in intel_pt_add_lbrs or by
     setting nr = 0), causing a SEGSEGV.
   * Fixed by ensuring ptq->last_branch is successfully allocated in
     intel_pt_alloc_queue() when add_last_branch is requested.

v6:
 - Address critical security and correctness feedback in Commit 2:
   * Fixed potential out-of-bounds read in perf_event__repipe_attr() by
     moving the header.size validation check before accessing
     event->attr.attr.size or copying.
   * Prevented 32-bit integer wrapping overflow on header.size validation
     by using subtraction instead of addition.
 - Restored PEBS LBR synthesis fixes in tools/perf/util/intel-pt.c.

v5:
 - Restored the missing PEBS branch stack synthesis fixes in intel-pt.c
   which were accidentally dropped in a previous rebase/conflict
   resolution.
 - Addressed the pipe mode size mismatch and ID array out-of-bounds read:
   * Safely copy the incoming attribute payload using min_t and
     memset zero, preventing trailing ID corruption.
   * Explicitly set the synthesized event's attr.size to match the tool's
     physical sizeof(struct perf_event_attr), guaranteeing perfect offset
     alignment and removing any risk of hallucinated/garbage IDs or
     underflow out-of-bounds reads.
 - Refactored both commit descriptions to strictly focus on code changes,
   deferring meta-commentary and implementation details exclusively to
   the cover letter.

v4:
 - Avoid temporary regressions in Commit 1:
   * Used local masked sample_type in convert_sample_callchain instead of
     unmasked evsel attribute, preventing heap overflows.
   * Promoted hardware tracer signature changes and dynamic retrieval of
     branch_sample_type to Commit 1, removing hardcoded 0 bugs.
   * Checked sample->evsel first before performing evlist__id2evsel lookup
     to optimize evsel retrieval when already populated.
 - Address critical security and correctness feedback in Commit 2:
   * Added check in perf_event__repipe_attr to prevent n_ids underflow.
   * Fixed early return error path in perf_event__repipe_sample to
     prevent state corruption and dangling pointers on dummy_bs.
   * Ensured perf_inject__cut_auxtrace_sample cuts the 8-byte size field
     even when aux_sample.size is 0 to prevent parser misalignment.
   * Expanded older attributes to PERF_ATTR_SIZE_VER2 in file mode
     within __cmd_inject to prevent silent truncation of
     branch_sample_type.
   * Added bounds checks against PERF_SAMPLE_MAX_SIZE to all hardware
     tracing synthetic helpers to prevent heap buffer overflows.
   * Fixed checkpatch.pl warnings/errors for line-wrapping.

v3:
 - Add missing Fixes: tags on both commits.
 - Refactor perf_event__repipe_attr to avoid in-place modifications on
   read-only mmap buffers, preventing SIGSEGV in file mode and premature
   evsel updates in pipe mode.
 - Use perf_event__synthesize_attr to correctly construct and repipe
   attributes in pipe mode.
 - Replace manual arithmetic in convert_sample_callchain with
   perf_event__sample_event_size to prevent uninitialized memory leaks.
 - Retrieve evsel branch_sample_type dynamically in util/arm-spe.c and
   util/cs-etm.c instead of hardcoding 0, resolving missing hw_idx field
   on synthesized branch stacks.

v2: Response to sashiko fixes for patch 2, Namhyung's acked-by for patch 1.

v1: https://lore.kernel.org/lkml/20260428070328.1880314-1-irogers@google.com/

Ian Rogers (2):
  perf event: Fix size of synthesized sample with branch stacks
  perf inject: Fix itrace branch stack synthesis

 tools/perf/bench/inject-buildid.c  |   9 +-
 tools/perf/builtin-inject.c        | 165 +++++++++++++++++++++++++----
 tools/perf/tests/dlfilter-test.c   |   8 +-
 tools/perf/tests/sample-parsing.c  |   5 +-
 tools/perf/util/arm-spe.c          |  28 ++++-
 tools/perf/util/cs-etm.c           |  28 ++++-
 tools/perf/util/intel-bts.c        |   3 +-
 tools/perf/util/intel-pt.c         |  35 ++++--
 tools/perf/util/synthetic-events.c |  25 +++--
 tools/perf/util/synthetic-events.h |   6 +-
 10 files changed, 260 insertions(+), 52 deletions(-)

-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v8 1/2] perf event: Fix size of synthesized sample with branch stacks

[Ian Rogers]

Synthesizing branch stacks for Intel-PT highlighted an issue where
PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the
perf_event_attr branch_sample_type. This caused an incorrect size
calculation.

Fix the writing of the nr and hw_idx values during sample event
synthesis by passing the branch_sample_type into the sample size
and synthesis functions. Also update hardware tracers (Intel PT,
ARM SPE, CS-ETM) to retrieve and pass their branch_sample_type
dynamically to prevent payload misalignment.

Fixes: d3f85437ad6a ("perf evsel: Support PERF_SAMPLE_BRANCH_HW_INDEX")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/bench/inject-buildid.c  |  9 ++++++---
 tools/perf/builtin-inject.c        | 12 +++++++++---
 tools/perf/tests/dlfilter-test.c   |  8 ++++++--
 tools/perf/tests/sample-parsing.c  |  5 +++--
 tools/perf/util/arm-spe.c          | 28 ++++++++++++++++++++++++----
 tools/perf/util/cs-etm.c           | 28 +++++++++++++++++++++++-----
 tools/perf/util/intel-bts.c        |  3 ++-
 tools/perf/util/intel-pt.c         | 27 +++++++++++++++++++++++----
 tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++-------
 tools/perf/util/synthetic-events.h |  6 ++++--
 10 files changed, 118 insertions(+), 33 deletions(-)

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7f..bfd2c5ec9488 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso,
 
 	event.header.type = PERF_RECORD_SAMPLE;
 	event.header.misc = PERF_RECORD_MISC_USER;
-	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
-
-	perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
+	event.header.size = perf_event__sample_event_size(&sample, bench_sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	perf_event__synthesize_sample(&event, bench_sample_type,
+				      /*read_format=*/0,
+				      /*branch_sample_type=*/0, &sample);
 
 	return writen(data->input_pipe[1], &event, event.header.size);
 }
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index a2493f1097df..2f20e782c7f2 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -465,8 +465,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
-	perf_event__synthesize_sample(event_copy, sample_type,
-				      evsel->core.attr.read_format, sample);
+	ret = perf_event__synthesize_sample(event_copy, sample_type,
+					    evsel->core.attr.read_format,
+					    evsel->core.attr.branch_sample_type, sample);
+	if (ret) {
+		pr_err("Failed to synthesize sample\n");
+		return ret;
+	}
 	return perf_event__repipe_synth(tool, event_copy);
 }
 
@@ -1102,7 +1107,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
 	sample_sw.period = sample->period;
 	sample_sw.time	 = sample->time;
 	perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
-				      evsel->core.attr.read_format, &sample_sw);
+				      evsel->core.attr.read_format,
+				      evsel->core.attr.branch_sample_type, &sample_sw);
 	build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
 	ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
 	perf_sample__exit(&sample_sw);
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index e63790c61d53..204663571943 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid
 
 	event->header.type = PERF_RECORD_SAMPLE;
 	event->header.misc = PERF_RECORD_MISC_USER;
-	event->header.size = perf_event__sample_event_size(&sample, sample_type, 0);
-	err = perf_event__synthesize_sample(event, sample_type, 0, &sample);
+	event->header.size = perf_event__sample_event_size(&sample, sample_type,
+							   /*read_format=*/0,
+							   /*branch_sample_type=*/0);
+	err = perf_event__synthesize_sample(event, sample_type,
+					    /*read_format=*/0,
+					    /*branch_sample_type=*/0, &sample);
 	if (err)
 		return test_result("perf_event__synthesize_sample() failed", TEST_FAIL);
 
diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
index a7327c942ca2..55f0b73ca20e 100644
--- a/tools/perf/tests/sample-parsing.c
+++ b/tools/perf/tests/sample-parsing.c
@@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 		sample.read.one.lost  = 1;
 	}
 
-	sz = perf_event__sample_event_size(&sample, sample_type, read_format);
+	sz = perf_event__sample_event_size(&sample, sample_type, read_format,
+					   evsel.core.attr.branch_sample_type);
 	bufsz = sz + 4096; /* Add a bit for overrun checking */
 	event = malloc(bufsz);
 	if (!event) {
@@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
 	event->header.size = sz;
 
 	err = perf_event__synthesize_sample(event, sample_type, read_format,
-					    &sample);
+					    evsel.core.attr.branch_sample_type, &sample);
 	if (err) {
 		pr_debug("%s failed for sample_type %#"PRIx64", error %d\n",
 			 "perf_event__synthesize_sample", sample_type, err);
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 2b31da231ef3..31f05f467810 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -487,10 +487,30 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
 	bstack->hw_idx = -1ULL;
 }
 
-static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
+static int arm_spe__inject_event(struct arm_spe *spe, union perf_event *event,
+				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && spe->session && spe->session->evlist)
+		evsel = evlist__id2evsel(spe->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int
@@ -502,7 +522,7 @@ arm_spe_deliver_synth_event(struct arm_spe *spe,
 	int ret;
 
 	if (spe->synth_opts.inject) {
-		ret = arm_spe__inject_event(event, sample, spe->sample_type);
+		ret = arm_spe__inject_event(spe, event, sample, spe->sample_type);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 8a639d2e51a4..6ec48de29441 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1422,11 +1422,29 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
 		bs->nr += 1;
 }
 
-static int cs_etm__inject_event(union perf_event *event,
+static int cs_etm__inject_event(struct cs_etm_auxtrace *etm, union perf_event *event,
 			       struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && etm->session && etm->session->evlist)
+		evsel = evlist__id2evsel(etm->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 
@@ -1592,7 +1610,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
 		sample.branch_stack = tidq->last_branch;
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->instructions_sample_type);
 		if (ret)
 			return ret;
@@ -1667,7 +1685,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
 	}
 
 	if (etm->synth_opts.inject) {
-		ret = cs_etm__inject_event(event, &sample,
+		ret = cs_etm__inject_event(etm, event, &sample,
 					   etm->branches_sample_type);
 		if (ret)
 			return ret;
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index 382255393fb3..0b18ebd13f7c 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq,
 		event.sample.header.size = bts->branches_event_size;
 		ret = perf_event__synthesize_sample(&event,
 						    bts->branches_sample_type,
-						    0, &sample);
+						    /*read_format=*/0, /*branch_sample_type=*/0,
+						    &sample);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index fc9eec8b54b8..dd2637678b40 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1728,11 +1728,30 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
 	event->sample.header.misc = sample->cpumode;
 }
 
-static int intel_pt_inject_event(union perf_event *event,
+static int intel_pt_inject_event(struct intel_pt *pt, union perf_event *event,
 				 struct perf_sample *sample, u64 type)
 {
-	event->header.size = perf_event__sample_event_size(sample, type, 0);
-	return perf_event__synthesize_sample(event, type, 0, sample);
+	struct evsel *evsel = sample->evsel;
+	u64 branch_sample_type = 0;
+	size_t sz;
+
+	if (!evsel && pt->session && pt->session->evlist)
+		evsel = evlist__id2evsel(pt->session->evlist, sample->id);
+
+	if (evsel)
+		branch_sample_type = evsel->core.attr.branch_sample_type;
+
+	event->header.type = PERF_RECORD_SAMPLE;
+	sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
+					   branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event->header.size = sz;
+
+	return perf_event__synthesize_sample(event, type, /*read_format=*/0,
+					     branch_sample_type, sample);
 }
 
 static inline int intel_pt_opt_inject(struct intel_pt *pt,
@@ -1742,7 +1761,7 @@ static inline int intel_pt_opt_inject(struct intel_pt *pt,
 	if (!pt->synth_opts.inject)
 		return 0;
 
-	return intel_pt_inject_event(event, sample, type);
+	return intel_pt_inject_event(pt, event, sample, type);
 }
 
 static int intel_pt_deliver_synth_event(struct intel_pt *pt,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 85bee747f4cd..2461f25a4d7d 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool,
 	return process(tool, (union perf_event *) &event, NULL, machine);
 }
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format)
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format,
+				     u64 branch_sample_type)
 {
 	size_t sz, result = sizeof(struct perf_record_sample);
 
@@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
+		/* nr */
+		sz += sizeof(u64);
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)
+			sz += sizeof(u64);
 		result += sz;
 	}
 
@@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format,
 }
 
 int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
-				  const struct perf_sample *sample)
+				  u64 branch_sample_type, const struct perf_sample *sample)
 {
 	__u64 *array;
 	size_t sz;
@@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
 
 	if (type & PERF_SAMPLE_BRANCH_STACK) {
 		sz = sample->branch_stack->nr * sizeof(struct branch_entry);
-		/* nr, hw_idx */
-		sz += 2 * sizeof(u64);
-		memcpy(array, sample->branch_stack, sz);
+
+		*array++ = sample->branch_stack->nr;
+
+		if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) {
+			if (sample->no_hw_idx)
+				*array++ = 0;
+			else
+				*array++ = sample->branch_stack->hw_idx;
+		}
+
+		memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz);
 		array = (void *)array + sz;
 	}
 
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index b0edad0c3100..8c7f49f9ccf5 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_
 int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
+int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
+				  u64 branch_sample_type, const struct perf_sample *sample);
 int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
 int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
@@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session,
 
 int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
 
-size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
+				     u64 read_format, u64 branch_sample_type);
 
 int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
-- 
2.54.0.631.ge1b05301d1-goog

[PATCH v8 2/2] perf inject: Fix itrace branch stack synthesis

[Ian Rogers]

When using "perf inject --itrace=L" to synthesize branch stacks from
AUX data, several issues caused failures with the generated file:

1. The synthesized samples were delivered without the
   PERF_SAMPLE_BRANCH_STACK flag if it was not in the original event's
   sample_type. Fixed by using sample_type | evsel->synth_sample_type
   in intel_pt_do_synth_pebs_sample.

2. Modifying evsel->core.attr.sample_type early in __cmd_inject caused
   parse failures for subsequent records in the input file. Fixed by
   moving this modification to just before writing the header.

3. perf_event__repipe_sample was narrowed to only synthesize samples
   when branch stack injection was requested, and restored the use of
   perf_inject__cut_auxtrace_sample as a fallback to preserve
   functionality.

4. Potential Heap Overflow in perf_event__repipe_sample: Addressed by
   adding a check that prints an error and returns -EFAULT if the
   calculated event size exceeds PERF_SAMPLE_MAX_SIZE.

5. Header vs Payload Mismatch in __cmd_inject: Addressed by narrowing
   the condition so that HEADER_BRANCH_STACK is only set in the file
   header if add_last_branch was true.

6. NULL Pointer Dereference in intel-pt.c: When branch stack injection
   is requested (add_last_branch is true) but last_branch is false
   (e.g., perf inject --itrace=L), ptq->last_branch was not allocated.
   However, PEBS branch stack synthesis (via synth_sample_type) still
   forced LBR handling in do_synth_pebs_sample(), dereferencing the
   NULL ptq->last_branch pointer. Guarding the dereference is not
   sufficient because downstream sample size calculation and synthesis
   strictly require a non-NULL branch_stack when the bit is set.
   Fixed by ensuring ptq->last_branch is allocated in
   intel_pt_alloc_queue() when add_last_branch is requested.

7. Modifying event attributes in perf_event__repipe_attr in-place caused
   SIGSEGV on read-only mmap buffers in file mode and downstream parser
   breakage in pipe mode. Fixed by processing the unmodified attribute
   first, returning immediately in non-pipe mode, and correctly
   synthesizing a new attribute event for pipe output using
   perf_event__synthesize_attr. Also:
   - Added a size validation check and integer underflow protection when
     parsing n_ids.
   - Prevented Trailing ID memory corruption by zero-initializing the
     local attr copy and safely copying using min_t(size_t, sizeof(attr),
     event->attr.attr.size).
   - Resolved ID array parsing mismatch downstream by expanding attr.size
     to sizeof(struct perf_event_attr) before synthesis to guarantee
     perfect header/attribute size alignment.

8. Potential dangling pointer vulnerability in perf_event__repipe_sample:
   Addressed by restoring the original sample->branch_stack pointer
   before returning, including on early error return paths.

9. Off-by-one error in sample size check in perf_event__repipe_sample:
   Fixed by checking if sz >= PERF_SAMPLE_MAX_SIZE instead of >.

10. Unadvertised size field left in payload by cut_auxtrace_sample:
    Addressed by excluding the 8-byte size field from the copied
    payload to correctly match the cleared PERF_SAMPLE_AUX bit. Cut
    the AUX sample payload even if size is 0.

11. Inaccurate sample size calculation and uninitialized memory leaks in
    convert_sample_callchain: Fixed by replacing manual arithmetic with
    perf_event__sample_event_size and adding a bounds check against
    PERF_SAMPLE_MAX_SIZE.

12. Omission of branch_sample_type in file headers: Addressed by
    expanding older, smaller attributes to PERF_ATTR_SIZE_VER2 in
    __cmd_inject to ensure branch_sample_type is not silently omitted.

Fixes: 0f0aa5e0693c ("perf inject: Add Instruction Tracing support")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-inject.c | 153 ++++++++++++++++++++++++++++++++----
 tools/perf/util/intel-pt.c  |   8 +-
 2 files changed, 142 insertions(+), 19 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 2f20e782c7f2..7a64935b7e2b 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -216,12 +216,23 @@ static int perf_event__repipe_op4_synth(const struct perf_tool *tool,
 	return perf_event__repipe_synth(tool, event);
 }
 
+static int perf_event__repipe_synth_cb(const struct perf_tool *tool,
+				       union perf_event *event,
+				       struct perf_sample *sample __maybe_unused,
+				       struct machine *machine __maybe_unused)
+{
+	return perf_event__repipe_synth(tool, event);
+}
+
 static int perf_event__repipe_attr(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct evlist **pevlist)
 {
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
 						  tool);
+	struct perf_event_attr attr;
+	size_t n_ids;
+	u64 *ids;
 	int ret;
 
 	ret = perf_event__process_attr(tool, event, pevlist);
@@ -232,7 +243,37 @@ static int perf_event__repipe_attr(const struct perf_tool *tool,
 	if (!inject->output.is_pipe)
 		return 0;
 
-	return perf_event__repipe_synth(tool, event);
+	if (!inject->itrace_synth_opts.set)
+		return perf_event__repipe_synth(tool, event);
+
+	if (event->header.size < sizeof(struct perf_event_header) + sizeof(u64)) {
+		pr_err("Attribute event size %u is too small\n", event->header.size);
+		return -EINVAL;
+	}
+
+	if (event->header.size - sizeof(event->header) < event->attr.attr.size) {
+		pr_err("Attribute event size %u is too small for attr.size %u\n",
+		       event->header.size, event->attr.attr.size);
+		return -EINVAL;
+	}
+
+	memset(&attr, 0, sizeof(attr));
+	memcpy(&attr, &event->attr.attr,
+	       min_t(size_t, sizeof(attr), (size_t)event->attr.attr.size));
+
+	n_ids = event->header.size - sizeof(event->header) - event->attr.attr.size;
+	n_ids /= sizeof(u64);
+	ids = perf_record_header_attr_id(event);
+
+	attr.size = sizeof(struct perf_event_attr);
+	attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+	if (inject->itrace_synth_opts.add_last_branch) {
+		attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+		attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+	}
+	return perf_event__synthesize_attr(tool, &attr, (u32)n_ids, ids,
+					   perf_event__repipe_synth_cb);
 }
 
 static int perf_event__repipe_event_update(const struct perf_tool *tool,
@@ -331,8 +372,8 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 				 union perf_event *event,
 				 struct perf_sample *sample)
 {
-	size_t sz1 = sample->aux_sample.data - (void *)event;
-	size_t sz2 = event->header.size - sample->aux_sample.size - sz1;
+	size_t sz1 = sample->aux_sample.data - (void *)event - sizeof(u64);
+	size_t sz2 = event->header.size - sample->aux_sample.size - (sz1 + sizeof(u64));
 	union perf_event *ev;
 
 	if (inject->event_copy == NULL) {
@@ -343,13 +384,12 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 	ev = (union perf_event *)inject->event_copy;
 	if (sz1 > event->header.size || sz2 > event->header.size ||
 	    sz1 + sz2 > event->header.size ||
-	    sz1 < sizeof(struct perf_event_header) + sizeof(u64))
+	    sz1 < sizeof(struct perf_event_header))
 		return event;
 
 	memcpy(ev, event, sz1);
 	memcpy((void *)ev + sz1, (void *)event + event->header.size - sz2, sz2);
 	ev->header.size = sz1 + sz2;
-	((u64 *)((void *)ev + sz1))[-1] = 0;
 
 	return ev;
 }
@@ -369,14 +409,77 @@ static int perf_event__repipe_sample(const struct perf_tool *tool,
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
 						  tool);
 
-	if (evsel && evsel->handler) {
+	if (evsel == NULL)
+		return perf_event__repipe_synth(tool, event);
+
+	if (evsel->handler) {
 		inject_handler f = evsel->handler;
 		return f(tool, event, sample, evsel, machine);
 	}
 
 	build_id__mark_dso_hit(tool, event, sample, evsel, machine);
 
-	if (inject->itrace_synth_opts.set && sample->aux_sample.size) {
+	if (inject->itrace_synth_opts.set &&
+	    (inject->itrace_synth_opts.last_branch ||
+	     inject->itrace_synth_opts.add_last_branch)) {
+		union perf_event *event_copy = (void *)inject->event_copy;
+		struct branch_stack dummy_bs = { .nr = 0, .hw_idx = 0 };
+		int err;
+		size_t sz;
+		u64 orig_type = evsel->core.attr.sample_type;
+		u64 orig_branch_type = evsel->core.attr.branch_sample_type;
+
+		struct branch_stack *orig_bs = sample->branch_stack;
+
+		if (event_copy == NULL) {
+			inject->event_copy = malloc(PERF_SAMPLE_MAX_SIZE);
+			if (!inject->event_copy)
+				return -ENOMEM;
+
+			event_copy = (void *)inject->event_copy;
+		}
+
+		if (!sample->branch_stack)
+			sample->branch_stack = &dummy_bs;
+
+		if (inject->itrace_synth_opts.add_last_branch) {
+			/* Temporarily add in type bits for synthesis. */
+			evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+			evsel->core.attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+		}
+		evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+
+		sz = perf_event__sample_event_size(sample, evsel->core.attr.sample_type,
+						   evsel->core.attr.read_format,
+						   evsel->core.attr.branch_sample_type);
+
+		if (sz >= PERF_SAMPLE_MAX_SIZE) {
+			pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+			evsel->core.attr.sample_type = orig_type;
+			evsel->core.attr.branch_sample_type = orig_branch_type;
+			sample->branch_stack = orig_bs;
+			return -EFAULT;
+		}
+
+		event_copy->header.type = PERF_RECORD_SAMPLE;
+		event_copy->header.misc = event->header.misc;
+		event_copy->header.size = sz;
+
+		err = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type,
+						    evsel->core.attr.read_format,
+						    evsel->core.attr.branch_sample_type, sample);
+
+		evsel->core.attr.sample_type = orig_type;
+		evsel->core.attr.branch_sample_type = orig_branch_type;
+		sample->branch_stack = orig_bs;
+
+		if (err) {
+			pr_err("Failed to synthesize sample\n");
+			return err;
+		}
+		event = event_copy;
+	} else if (inject->itrace_synth_opts.set &&
+		   (evsel->core.attr.sample_type & PERF_SAMPLE_AUX)) {
 		event = perf_inject__cut_auxtrace_sample(inject, event, sample);
 		if (IS_ERR(event))
 			return PTR_ERR(event);
@@ -397,7 +500,7 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 	struct callchain_cursor_node *node;
 	struct thread *thread;
 	u64 sample_type = evsel->core.attr.sample_type;
-	u32 sample_size = event->header.size;
+	size_t sz;
 	u64 i, k;
 	int ret;
 
@@ -456,15 +559,18 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool,
 out:
 	memcpy(event_copy, event, sizeof(event->header));
 
-	/* adjust sample size for stack and regs */
-	sample_size -= sample->user_stack.size;
-	sample_size -= (hweight64(evsel->core.attr.sample_regs_user) + 1) * sizeof(u64);
-	sample_size += (sample->callchain->nr + 1) * sizeof(u64);
-	event_copy->header.size = sample_size;
-
 	/* remove sample_type {STACK,REGS}_USER for synthesize */
 	sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER);
 
+	sz = perf_event__sample_event_size(sample, sample_type,
+					   evsel->core.attr.read_format,
+					   evsel->core.attr.branch_sample_type);
+	if (sz >= PERF_SAMPLE_MAX_SIZE) {
+		pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
+		return -EFAULT;
+	}
+	event_copy->header.size = sz;
+
 	ret = perf_event__synthesize_sample(event_copy, sample_type,
 					    evsel->core.attr.read_format,
 					    evsel->core.attr.branch_sample_type, sample);
@@ -2442,12 +2548,27 @@ static int __cmd_inject(struct perf_inject *inject)
 		 * synthesized hardware events, so clear the feature flag.
 		 */
 		if (inject->itrace_synth_opts.set) {
+			struct evsel *evsel;
+
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
-			if (inject->itrace_synth_opts.last_branch ||
-			    inject->itrace_synth_opts.add_last_branch)
+
+			evlist__for_each_entry(session->evlist, evsel) {
+				evsel->core.attr.sample_type &= ~PERF_SAMPLE_AUX;
+			}
+
+			if (inject->itrace_synth_opts.add_last_branch) {
 				perf_header__set_feat(&session->header,
 						      HEADER_BRANCH_STACK);
+
+				evlist__for_each_entry(session->evlist, evsel) {
+					evsel->core.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+					if (evsel->core.attr.size < PERF_ATTR_SIZE_VER2)
+						evsel->core.attr.size = PERF_ATTR_SIZE_VER2;
+					evsel->core.attr.branch_sample_type |=
+						PERF_SAMPLE_BRANCH_HW_INDEX;
+				}
+			}
 		}
 
 		/*
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index dd2637678b40..d9c86ac49748 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1307,7 +1307,8 @@ static struct intel_pt_queue *intel_pt_alloc_queue(struct intel_pt *pt,
 			goto out_free;
 	}
 
-	if (pt->synth_opts.last_branch || pt->synth_opts.other_events) {
+	if (pt->synth_opts.last_branch || pt->synth_opts.add_last_branch ||
+	    pt->synth_opts.other_events) {
 		unsigned int entry_cnt = max(LBRS_MAX, pt->br_stack_sz);
 
 		ptq->last_branch = intel_pt_alloc_br_stack(entry_cnt);
@@ -2505,7 +2506,7 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		intel_pt_add_xmm(intr_regs, pos, items, regs_mask);
 	}
 
-	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+	if ((sample_type | evsel->synth_sample_type) & PERF_SAMPLE_BRANCH_STACK) {
 		if (items->mask[INTEL_PT_LBR_0_POS] ||
 		    items->mask[INTEL_PT_LBR_1_POS] ||
 		    items->mask[INTEL_PT_LBR_2_POS]) {
@@ -2576,7 +2577,8 @@ static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evse
 		sample.transaction = txn;
 	}
 
-	ret = intel_pt_deliver_synth_event(pt, event, &sample, sample_type);
+	ret = intel_pt_deliver_synth_event(pt, event, &sample,
+					   sample_type | evsel->synth_sample_type);
 	perf_sample__exit(&sample);
 	return ret;
 }
-- 
2.54.0.631.ge1b05301d1-goog

Re: [PATCH v8 0/2] perf inject intel-PT LBR/brstack synthesis fixes

[Arnaldo Carvalho de Melo]

On Mon, May 18, 2026 at 03:43:23PM -0700, Ian Rogers wrote:
> An intel-pt trace can be turned into LBR events either in perf script
> or perf inject with the --itrace=L option. With perf inject the
> generated perf.data file failed to be parsed as the sample events were
> out of sync with their perf_event_attr. A range of fixes were
> required.
> 
> This patch was separated from a large perf script refactor that
> highlighted the breakage:
> https://lore.kernel.org/lkml/20260425224951.174663-1-irogers@google.com/

Thanks, applied to perf-tools-next, for v7.2.

- Arnaldo