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5ddacef6 SLM |
1 | From 3aab4df41bb811b40815bdfc42158254fd8ddfe3 Mon Sep 17 00:00:00 2001 |
2 | From: Stephane Eranian <eranian@google.com> | |
3 | Date: Thu, 7 Mar 2019 10:52:33 -0800 | |
4 | Subject: perf/core: Restore mmap record type correctly | |
5 | ||
6 | [ Upstream commit d9c1bb2f6a2157b38e8eb63af437cb22701d31ee ] | |
7 | ||
8 | On mmap(), perf_events generates a RECORD_MMAP record and then checks | |
9 | which events are interested in this record. There are currently 2 | |
10 | versions of mmap records: RECORD_MMAP and RECORD_MMAP2. MMAP2 is larger. | |
11 | The event configuration controls which version the user level tool | |
12 | accepts. | |
13 | ||
14 | If the event->attr.mmap2=1 field then MMAP2 record is returned. The | |
15 | perf_event_mmap_output() takes care of this. It checks attr->mmap2 and | |
16 | corrects the record fields before putting it in the sampling buffer of | |
17 | the event. At the end the function restores the modified MMAP record | |
18 | fields. | |
19 | ||
20 | The problem is that the function restores the size but not the type. | |
21 | Thus, if a subsequent event only accepts MMAP type, then it would | |
22 | instead receive an MMAP2 record with a size of MMAP record. | |
23 | ||
24 | This patch fixes the problem by restoring the record type on exit. | |
25 | ||
26 | Signed-off-by: Stephane Eranian <eranian@google.com> | |
27 | Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> | |
28 | Cc: Andi Kleen <ak@linux.intel.com> | |
29 | Cc: Jiri Olsa <jolsa@redhat.com> | |
30 | Cc: Kan Liang <kan.liang@linux.intel.com> | |
31 | Fixes: 13d7a2410fa6 ("perf: Add attr->mmap2 attribute to an event") | |
32 | Link: http://lkml.kernel.org/r/20190307185233.225521-1-eranian@google.com | |
33 | Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> | |
34 | Signed-off-by: Sasha Levin <sashal@kernel.org> | |
35 | --- | |
36 | kernel/events/core.c | 2 ++ | |
37 | 1 file changed, 2 insertions(+) | |
38 | ||
39 | diff --git a/kernel/events/core.c b/kernel/events/core.c | |
40 | index 5cbb2eda80b5..7929526e96e2 100644 | |
41 | --- a/kernel/events/core.c | |
42 | +++ b/kernel/events/core.c | |
43 | @@ -6616,6 +6616,7 @@ static void perf_event_mmap_output(struct perf_event *event, | |
44 | struct perf_output_handle handle; | |
45 | struct perf_sample_data sample; | |
46 | int size = mmap_event->event_id.header.size; | |
47 | + u32 type = mmap_event->event_id.header.type; | |
48 | int ret; | |
49 | ||
50 | if (!perf_event_mmap_match(event, data)) | |
51 | @@ -6659,6 +6660,7 @@ static void perf_event_mmap_output(struct perf_event *event, | |
52 | perf_output_end(&handle); | |
53 | out: | |
54 | mmap_event->event_id.header.size = size; | |
55 | + mmap_event->event_id.header.type = type; | |
56 | } | |
57 | ||
58 | static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) | |
59 | -- | |
60 | 2.19.1 | |
61 |