[PATCH v4 4/5] perf/powerpc: Count dropped samples in core-book3s PMU

[Namhyung Kim <namhyung@kernel.org>]

Due to the hardware limitation, sometimes it could sample kernel address
while attr.exclude_kernel is set.  In that case it silently drops the
sample.  Let's count that case in the new dropped_samples counter.

Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 arch/powerpc/perf/core-book3s.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 42867469752d73cf..553e288b9f113836 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -2287,8 +2287,10 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
 	 */
 	if (event->attr.exclude_kernel &&
 	    (event->attr.sample_type & PERF_SAMPLE_IP) &&
-	    is_kernel_addr(mfspr(SPRN_SIAR)))
+	    is_kernel_addr(mfspr(SPRN_SIAR))) {
+		atomic64_inc(&event->dropped_samples);
 		record = 0;
+	}
 
 	/*
 	 * Finally record data if requested.
-- 
2.47.0.105.g07ac214952-goog