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

From: Namhyung Kim
Date: Fri Aug 30 2024 - 19:29:31 EST


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@xxxxxxxxxx>
---
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