[RFC/PATCH 2/4] perf/core: Export perf_exclude_event()

[Namhyung Kim <namhyung@kernel.org>]

And increase the dropped_sample count when it returns 1.  Now it can
track how many samples are dropped due to the privilege filters in
software events.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 include/linux/perf_event.h |  2 ++
 kernel/events/core.c       | 11 +++++++----
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 955d39543398..c93673a8d66a 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1634,6 +1634,8 @@ static inline int perf_allow_tracepoint(struct perf_event_attr *attr)
 	return security_perf_event_open(attr, PERF_SECURITY_TRACEPOINT);
 }
 
+extern int perf_exclude_event(struct perf_event *event, struct pt_regs *regs);
+
 extern void perf_event_init(void);
 extern void perf_tp_event(u16 event_type, u64 count, void *record,
 			  int entry_size, struct pt_regs *regs,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4d72538628ee..8250e76f6335 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9978,18 +9978,21 @@ static void perf_swevent_event(struct perf_event *event, u64 nr,
 	perf_swevent_overflow(event, 0, data, regs);
 }
 
-static int perf_exclude_event(struct perf_event *event,
-			      struct pt_regs *regs)
+int perf_exclude_event(struct perf_event *event, struct pt_regs *regs)
 {
 	if (event->hw.state & PERF_HES_STOPPED)
 		return 1;
 
 	if (regs) {
-		if (event->attr.exclude_user && user_mode(regs))
+		if (event->attr.exclude_user && user_mode(regs)) {
+			atomic64_inc(&event->dropped_samples);
 			return 1;
+		}
 
-		if (event->attr.exclude_kernel && !user_mode(regs))
+		if (event->attr.exclude_kernel && !user_mode(regs)) {
+			atomic64_inc(&event->dropped_samples);
 			return 1;
+		}
 	}
 
 	return 0;
-- 
2.46.0.469.g59c65b2a67-goog