[PATCH v4 2/5] perf/core: Export perf_exclude_event()

[Namhyung Kim <namhyung@xxxxxxxxxx>]

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.

While at it, rename the same function in s390 cpum_sf PMU and also count
the dropped samples.

Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: Thomas Richter <tmricht@xxxxxxxxxxxxx>
Cc: linux-s390@xxxxxxxxxxxxxxx
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 arch/s390/kernel/perf_cpum_sf.c |  8 +++++---
 include/linux/perf_event.h      |  6 ++++++
 kernel/events/core.c            | 11 +++++++----
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index 5b765e3ccf0cadc8..ff9e694f2be45c6b 100644
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -996,7 +996,7 @@ static void cpumsf_pmu_disable(struct pmu *pmu)
 	cpuhw->flags &= ~PMU_F_ENABLED;
 }
 
-/* perf_exclude_event() - Filter event
+/* perf_event_exclude() - Filter event
  * @event:	The perf event
  * @regs:	pt_regs structure
  * @sde_regs:	Sample-data-entry (sde) regs structure
@@ -1005,7 +1005,7 @@ static void cpumsf_pmu_disable(struct pmu *pmu)
  *
  * Return non-zero if the event shall be excluded.
  */
-static int perf_exclude_event(struct perf_event *event, struct pt_regs *regs,
+static int perf_event_exclude(struct perf_event *event, struct pt_regs *regs,
 			      struct perf_sf_sde_regs *sde_regs)
 {
 	if (event->attr.exclude_user && user_mode(regs))
@@ -1088,8 +1088,10 @@ static int perf_push_sample(struct perf_event *event,
 	data.tid_entry.pid = basic->hpp & LPP_PID_MASK;
 
 	overflow = 0;
-	if (perf_exclude_event(event, &regs, sde_regs))
+	if (perf_event_exclude(event, &regs, sde_regs)) {
+		atomic64_inc(&event->dropped_samples);
 		goto out;
+	}
 	if (perf_event_overflow(event, &data, &regs)) {
 		overflow = 1;
 		event->pmu->stop(event, 0);
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index c1e6340e561c400e..6b31958a2b1db8db 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1649,6 +1649,8 @@ 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,
@@ -1832,6 +1834,10 @@ static inline u64 perf_event_pause(struct perf_event *event, bool reset)
 {
 	return 0;
 }
+static inline int perf_exclude_event(struct perf_event *event, struct pt_regs *regs)
+{
+	return 0;
+}
 #endif
 
 #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7e15fe0a8dee4ee7..5d24597180dec167 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10001,18 +10001,21 @@ 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;
-- 
2.47.0.105.g07ac214952-goog