[RFC][PATCH 07/10] tracing: Add eBPF program support to static trace events

[Tom Zanussi <tom.zanussi@linux.intel.com>]

Have perf_trace_*() and perf_syscall_enter()/exit() make calls to
trace_call_bpf() if there's a TRACE_EVENT program associated with a
trace event.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 include/trace/perf.h          | 10 ++++++++++
 kernel/trace/trace_syscalls.c | 18 ++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/include/trace/perf.h b/include/trace/perf.h
index 26486fc..0d8069c 100644
--- a/include/trace/perf.h
+++ b/include/trace/perf.h
@@ -1,3 +1,5 @@
+#include <linux/filter.h>
+#include <linux/bpf.h>
 
 #undef TRACE_SYSTEM_VAR
 
@@ -35,6 +37,7 @@ static notrace void							\
 perf_trace_##call(void *__data, proto)					\
 {									\
 	struct trace_event_call *event_call = __data;			\
+	struct bpf_prog *prog = event_call->prog;			\
 	struct trace_event_data_offsets_##call __maybe_unused __data_offsets;\
 	struct trace_event_raw_##call *entry;				\
 	struct pt_regs *__regs;						\
@@ -67,6 +70,13 @@ perf_trace_##call(void *__data, proto)					\
 									\
 	{ assign; }							\
 									\
+	if (prog && prog->type == BPF_PROG_TYPE_TRACE_EVENT) {		\
+		struct trace_event_context ctx = { event_call, entry };	\
+									\
+		if (!trace_call_bpf(prog, &ctx))			\
+			return;						\
+	}								\
+									\
 	perf_trace_buf_submit(entry, __entry_size, rctx, __addr,	\
 		__count, __regs, head, __task);				\
 }
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 50be560..feea899 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -6,6 +6,8 @@
 #include <linux/module.h>	/* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */
 #include <linux/ftrace.h>
 #include <linux/perf_event.h>
+#include <linux/filter.h>
+#include <linux/bpf.h>
 #include <asm/syscall.h>
 
 #include "trace_output.h"
@@ -562,6 +564,7 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 	struct syscall_metadata *sys_data;
 	struct syscall_trace_enter *rec;
 	struct hlist_head *head;
+	struct bpf_prog *prog;
 	int syscall_nr;
 	int rctx;
 	int size;
@@ -576,6 +579,8 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 	if (!sys_data)
 		return;
 
+	prog = sys_data->enter_event->prog;
+
 	head = this_cpu_ptr(sys_data->enter_event->perf_events);
 	if (hlist_empty(head))
 		return;
@@ -593,6 +598,11 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 	rec->nr = syscall_nr;
 	syscall_get_arguments(current, regs, 0, sys_data->nb_args,
 			       (unsigned long *)&rec->args);
+	if (prog && prog->type == BPF_PROG_TYPE_TRACE_EVENT) {
+		struct trace_event_context ctx = { sys_data->enter_event, rec };
+		if (!trace_call_bpf(prog, &ctx))
+			return;
+	}
 	perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 }
 
@@ -636,6 +646,7 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 	struct syscall_metadata *sys_data;
 	struct syscall_trace_exit *rec;
 	struct hlist_head *head;
+	struct bpf_prog *prog;
 	int syscall_nr;
 	int rctx;
 	int size;
@@ -650,6 +661,8 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 	if (!sys_data)
 		return;
 
+	prog = sys_data->enter_event->prog;
+
 	head = this_cpu_ptr(sys_data->exit_event->perf_events);
 	if (hlist_empty(head))
 		return;
@@ -665,6 +678,11 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 
 	rec->nr = syscall_nr;
 	rec->ret = syscall_get_return_value(current, regs);
+	if (prog && prog->type == BPF_PROG_TYPE_TRACE_EVENT) {
+		struct trace_event_context ctx = { sys_data->exit_event, rec };
+		if (!trace_call_bpf(prog, &ctx))
+			return;
+	}
 	perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 }
 
-- 
1.9.3