From: Stephane Eranian eranian@google.com
[ Upstream commit d9c1bb2f6a2157b38e8eb63af437cb22701d31ee ]
On mmap(), perf_events generates a RECORD_MMAP record and then checks which events are interested in this record. There are currently 2 versions of mmap records: RECORD_MMAP and RECORD_MMAP2. MMAP2 is larger. The event configuration controls which version the user level tool accepts.
If the event->attr.mmap2=1 field then MMAP2 record is returned. The perf_event_mmap_output() takes care of this. It checks attr->mmap2 and corrects the record fields before putting it in the sampling buffer of the event. At the end the function restores the modified MMAP record fields.
The problem is that the function restores the size but not the type. Thus, if a subsequent event only accepts MMAP type, then it would instead receive an MMAP2 record with a size of MMAP record.
This patch fixes the problem by restoring the record type on exit.
Signed-off-by: Stephane Eranian eranian@google.com Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Cc: Andi Kleen ak@linux.intel.com Cc: Jiri Olsa jolsa@redhat.com Cc: Kan Liang kan.liang@linux.intel.com Fixes: 13d7a2410fa6 ("perf: Add attr->mmap2 attribute to an event") Link: http://lkml.kernel.org/r/20190307185233.225521-1-eranian@google.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/events/core.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/kernel/events/core.c b/kernel/events/core.c index aa996a0854b9..87bd96399d1c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7178,6 +7178,7 @@ static void perf_event_mmap_output(struct perf_event *event, struct perf_output_handle handle; struct perf_sample_data sample; int size = mmap_event->event_id.header.size; + u32 type = mmap_event->event_id.header.type; int ret;
if (!perf_event_mmap_match(event, data)) @@ -7221,6 +7222,7 @@ static void perf_event_mmap_output(struct perf_event *event, perf_output_end(&handle); out: mmap_event->event_id.header.size = size; + mmap_event->event_id.header.type = type; }
static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)