* [PATCH bpf-next 1/2] selftests/bpf: Move verifier failure tests out of test_global_percpu_data
@ 2026-09-04 3:19 Thiébaud Weksteen
2026-09-04 3:19 ` [PATCH bpf-next 2/2] bpftool: Reject non-autoload programs for light skeletons Thiébaud Weksteen
2026-09-04 6:07 ` [PATCH bpf-next 1/2] selftests/bpf: Move verifier failure tests out of test_global_percpu_data Leon Hwang
0 siblings, 2 replies; 4+ messages in thread
From: Thiébaud Weksteen @ 2026-09-04 3:19 UTC (permalink / raw)
To: Quentin Monnet, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi,
Shuah Khan, Leon Hwang, Emil Tsalapatis, Thiébaud Weksteen
Cc: Martin KaFai Lau, Song Liu, Yonghong Song, Jiri Olsa,
Ihor Solodrai, Sid Nayyar, linux-kernel, bpf, linux-kselftest
Commit 4c9241bd731a ("selftests/bpf: Add tests to verify global percpu
data") added test_global_percpu_data.c to LSKELS_EXTRA. Later, in commit
1ed2294b31fc ("selftests/bpf: Test verifier log for global percpu data")
two verifier failure tests were added (verifier_strncmp and
verifier_snprintf), both marked as non-autoload (SEC("?kprobe")).
When bpftool generates light skeletons, non-autoloaded programs are
skipped during loading, causing the loader program to store subsequent
program FDs into incorrect skeleton struct fields (e.g. dump_percpu_data's
FD was stored into verifier_strncmp's descriptor).
Move the two verifier failure tests to a dedicated test file,
test_global_percpu_data_failure.c, and run them via RUN_TESTS in
global_data_init.c. This leaves test_global_percpu_data.c with only
autoloaded programs, ensuring the light skeleton can be generated cleanly
and correctly.
Fixes: 4c9241bd731a ("selftests/bpf: Add tests to verify global percpu data")
Fixes: 1ed2294b31fc ("selftests/bpf: Test verifier log for global percpu data")
Signed-off-by: Thiébaud Weksteen <tweek@google.com>
---
.../bpf/prog_tests/global_data_init.c | 3 +-
.../bpf/progs/test_global_percpu_data.c | 23 --------------
.../progs/test_global_percpu_data_failure.c | 30 +++++++++++++++++++
3 files changed, 32 insertions(+), 24 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c
diff --git a/tools/testing/selftests/bpf/prog_tests/global_data_init.c b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
index 7c539cbcf3a1..dbb7de534f7d 100644
--- a/tools/testing/selftests/bpf/prog_tests/global_data_init.c
+++ b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
@@ -3,6 +3,7 @@
#include "bpf/libbpf_internal.h"
#include "test_global_percpu_data.skel.h"
#include "test_global_percpu_data.lskel.h"
+#include "test_global_percpu_data_failure.skel.h"
void test_global_data_init(void)
{
@@ -372,7 +373,7 @@ static void test_global_percpu_data_rdonly_direct_write(void)
static void test_global_percpu_data_verifier_log(void)
{
- RUN_TESTS(test_global_percpu_data);
+ RUN_TESTS(test_global_percpu_data_failure);
}
static void test_global_percpu_data_iter(void)
diff --git a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
index 2765cd46e9af..bc748df4a6cc 100644
--- a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
+++ b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
@@ -42,29 +42,6 @@ int update_percpu_data(void *ctx)
return 0;
}
-static const char fmt[] SEC(".percpu.fmt") = "data %d\n";
-
-SEC("?kprobe")
-__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
-int verifier_strncmp(void *ctx)
-{
- return bpf_strncmp("test", 5, fmt);
-}
-
-SEC("?kprobe")
-__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
-int verifier_snprintf(void *ctx)
-{
- u64 args[] = { data };
- char buf[128];
- int len;
-
- len = bpf_snprintf(buf, sizeof(buf), fmt, args, sizeof(args));
- if (len > 0)
- bpf_printk("snprintf: %s\n", buf);
- return 0;
-}
-
volatile const __u32 num_cpus = 0;
volatile const int num_off;
volatile const int elem_sz;
diff --git a/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c b/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c
new file mode 100644
index 000000000000..3a823acb42d7
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+int data SEC(".percpu") = -1;
+static const char fmt[] SEC(".percpu.fmt") = "data %d\n";
+
+SEC("?kprobe")
+__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
+int verifier_strncmp(void *ctx)
+{
+ return bpf_strncmp("test", 5, fmt);
+}
+
+SEC("?kprobe")
+__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
+int verifier_snprintf(void *ctx)
+{
+ u64 args[] = { data };
+ char buf[128];
+ int len;
+
+ len = bpf_snprintf(buf, sizeof(buf), fmt, args, sizeof(args));
+ if (len > 0)
+ bpf_printk("snprintf: %s\n", buf);
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.55.0.979.g7e5102b832-goog
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH bpf-next 2/2] bpftool: Reject non-autoload programs for light skeletons
2026-09-04 3:19 [PATCH bpf-next 1/2] selftests/bpf: Move verifier failure tests out of test_global_percpu_data Thiébaud Weksteen
@ 2026-09-04 3:19 ` Thiébaud Weksteen
2026-09-04 4:13 ` bot+bpf-ci
2026-09-04 6:07 ` [PATCH bpf-next 1/2] selftests/bpf: Move verifier failure tests out of test_global_percpu_data Leon Hwang
1 sibling, 1 reply; 4+ messages in thread
From: Thiébaud Weksteen @ 2026-09-04 3:19 UTC (permalink / raw)
To: Quentin Monnet, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi,
Shuah Khan, Leon Hwang, Emil Tsalapatis, Thiébaud Weksteen
Cc: Martin KaFai Lau, Song Liu, Yonghong Song, Jiri Olsa,
Ihor Solodrai, Sid Nayyar, linux-kernel, bpf, linux-kselftest
When generating a light skeleton (bpftool gen skeleton -L), there is no
libbpf runtime object or bpf_program__set_autoload() API available to
enable/disable the autoloading of programs. If a BPF program in the
object has autoload disabled (e.g. via SEC("?...")), bpf_object__load()
silently skips loading it. bpftool still generates struct bpf_prog_desc
fields and attach functions in the light skeleton header, leaving
skel->progs.<name>.prog_fd uninitialized (0).
Explicitly reject non-autoloaded programs when use_loader is true with
an error message, preventing the generation of broken light skeleton
headers.
Signed-off-by: Thiébaud Weksteen <tweek@google.com>
---
tools/bpf/bpftool/gen.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index a50540ef6521..1583150241c8 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -1340,6 +1340,12 @@ static int do_skeleton(int argc, char **argv)
}
bpf_object__for_each_program(prog, obj) {
prog_cnt++;
+
+ if (use_loader && !bpf_program__autoload(prog)) {
+ p_err("program '%s' is marked as non-autoload, which is not supported for light skeletons",
+ bpf_program__name(prog));
+ return -1;
+ }
}
get_header_guard(header_guard, obj_name, "SKEL_H");
--
2.55.0.979.g7e5102b832-goog
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH bpf-next 2/2] bpftool: Reject non-autoload programs for light skeletons
2026-09-04 3:19 ` [PATCH bpf-next 2/2] bpftool: Reject non-autoload programs for light skeletons Thiébaud Weksteen
@ 2026-09-04 4:13 ` bot+bpf-ci
0 siblings, 0 replies; 4+ messages in thread
From: bot+bpf-ci @ 2026-09-04 4:13 UTC (permalink / raw)
To: tweek, qmo, ast, daniel, andrii, eddyz87, memxor, shuah,
leon.hwang, emil, tweek
Cc: martin.lau, song, yonghong.song, jolsa, ihor.solodrai, sidnayyar,
linux-kernel, bpf, linux-kselftest, ast, andrii, daniel,
martin.lau, eddyz87, yonghong.song, mason, ihor.solodrai
[-- Attachment #1: Type: text/plain, Size: 1387 bytes --]
> commit 2f59d25442273a3dd4e46bd4a77ca4bbf1633e3c
> Author: Thiébaud Weksteen <tweek@google.com>
> Date: Fri Sep 4 13:19:12 2026 +1000
>
> bpftool: Reject non-autoload programs for light skeletons
>
> When generating a light skeleton (bpftool gen skeleton -L), there is no
> libbpf runtime object or bpf_program__set_autoload() API available to
> enable/disable the autoloading of programs. If a BPF program in the
> object has autoload disabled (e.g. via SEC("?...")), bpf_object__load()
> silently skips loading it. bpftool still generates struct bpf_prog_desc
> fields and attach functions in the light skeleton header, leaving
> skel->progs.<name>.prog_fd uninitialized (0).
>
> Explicitly reject non-autoloaded programs when use_loader is true with
> an error message, preventing the generation of broken light skeleton
> headers.
>
> Signed-off-by: Thiébaud Weksteen <tweek@google.com>
This looks like a bug fix for light skeleton generation. Should this
include a Fixes: tag?
Fixes: d510296d331a ("bpftool: Use syscall/loader program in \"prog load\" and \"gen skeleton\" command.")
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/33833567672
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next 1/2] selftests/bpf: Move verifier failure tests out of test_global_percpu_data
2026-09-04 3:19 [PATCH bpf-next 1/2] selftests/bpf: Move verifier failure tests out of test_global_percpu_data Thiébaud Weksteen
2026-09-04 3:19 ` [PATCH bpf-next 2/2] bpftool: Reject non-autoload programs for light skeletons Thiébaud Weksteen
@ 2026-09-04 6:07 ` Leon Hwang
1 sibling, 0 replies; 4+ messages in thread
From: Leon Hwang @ 2026-09-04 6:07 UTC (permalink / raw)
To: Thiébaud Weksteen, Quentin Monnet, Alexei Starovoitov,
Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman,
Kumar Kartikeya Dwivedi, Shuah Khan, Emil Tsalapatis
Cc: Martin KaFai Lau, Song Liu, Yonghong Song, Jiri Olsa,
Ihor Solodrai, Sid Nayyar, linux-kernel, bpf, linux-kselftest
On 4/9/26 11:19, Thiébaud Weksteen wrote:
> Commit 4c9241bd731a ("selftests/bpf: Add tests to verify global percpu
> data") added test_global_percpu_data.c to LSKELS_EXTRA. Later, in commit
> 1ed2294b31fc ("selftests/bpf: Test verifier log for global percpu data")
> two verifier failure tests were added (verifier_strncmp and
> verifier_snprintf), both marked as non-autoload (SEC("?kprobe")).
>
> When bpftool generates light skeletons, non-autoloaded programs are
> skipped during loading, causing the loader program to store subsequent
> program FDs into incorrect skeleton struct fields (e.g. dump_percpu_data's
> FD was stored into verifier_strncmp's descriptor).
IIUC, patch 2 will fix the issue totally.
Better to add a subtest to verify both the issue and the fix?
Thanks,
Leon
> [...]
^ permalink raw reply [flat|nested] 4+ messages in thread
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2026-09-04 3:19 [PATCH bpf-next 1/2] selftests/bpf: Move verifier failure tests out of test_global_percpu_data Thiébaud Weksteen
2026-09-04 3:19 ` [PATCH bpf-next 2/2] bpftool: Reject non-autoload programs for light skeletons Thiébaud Weksteen
2026-09-04 4:13 ` bot+bpf-ci
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