Merge branch 'bpf-add-support-for-sys-enter-exit-tracepoints'

Yonghong Song says:

====================
bpf: add support for sys_{enter|exit}_* tracepoints

Currently, bpf programs cannot be attached to sys_enter_* and sys_exit_*
style tracepoints. The main reason is that syscalls/sys_enter_* and syscalls/sys_exit_*
tracepoints are treated differently from other tracepoints and there
is no bpf hook to it.

This patch set adds bpf support for these syscalls tracepoints and also
adds a test case for it.

Changelogs:
v3 -> v4:
 - Check the legality of ctx offset access for syscall tracepoint as well.
   trace_event_get_offsets will return correct max offset for each
   specific syscall tracepoint.
 - Use variable length array to avoid hardcode 6 as the maximum
   arguments beyond syscall_nr.
v2 -> v3:
 - Fix a build issue
v1 -> v2:
 - Do not use TRACE_EVENT_FL_CAP_ANY to identify syscall tracepoint.
   Instead use trace_event_call->class.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 3cb15ea48aee..c9170218e9e6 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -172,8 +172,20 @@ extern struct trace_event_functions exit_syscall_print_funcs;
 	static struct syscall_metadata __used			\
 	  __attribute__((section("__syscalls_metadata")))	\
 	 *__p_syscall_meta_##sname = &__syscall_meta_##sname;
+
+static inline int is_syscall_trace_event(struct trace_event_call *tp_event)
+{
+	return tp_event->class == &event_class_syscall_enter ||
+	       tp_event->class == &event_class_syscall_exit;
+}
+
 #else
 #define SYSCALL_METADATA(sname, nb, ...)
+
+static inline int is_syscall_trace_event(struct trace_event_call *tp_event)
+{
+	return 0;
+}
 #endif
 
 #define SYSCALL_DEFINE0(sname)					\