[tip:perf/urgent] perf evsel: Store ids for events with their own cpus perf_event__synthesize_event_update_cpus

From: tip-bot for Jiri Olsa
Date: Thu Oct 18 2018 - 02:21:20 EST

Commit-ID: 4ab8455f8bd83298bf7f67ab9357e3b1cc765c7d
Gitweb: https://git.kernel.org/tip/4ab8455f8bd83298bf7f67ab9357e3b1cc765c7d
Author: Jiri Olsa <jolsa@xxxxxxxxxx>
AuthorDate: Wed, 3 Oct 2018 23:20:52 +0200
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 16 Oct 2018 08:18:52 -0300

perf evsel: Store ids for events with their own cpus perf_event__synthesize_event_update_cpus

John reported crash when recording on an event under PMU with cpumask defined:

root@localhost:~# ./perf_debug_ record -e armv8_pmuv3_0/br_mis_pred/ sleep 1
perf: Segmentation fault
Obtained 9 stack frames.
./perf_debug_() [0x4c5ef8]
./perf_debug_() [0x4bc5a8]
./perf_debug_() [0x419550]
./perf_debug_() [0x41a928]
./perf_debug_() [0x472f58]
./perf_debug_() [0x473210]
./perf_debug_() [0x4070f4]
/lib/aarch64-linux-gnu/libc.so.6(__libc_start_main+0xe0) [0xffff8294c8a0]
Segmentation fault (core dumped)

We synthesize an update event that needs to touch the evsel id array, which is
not defined at that time. Fixing this by forcing the id allocation for events
with their own cpus.

Reported-by: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Tested-by: John Garry <john.garry@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linuxarm@xxxxxxxxxx
Fixes: bfd8f72c2778 ("perf record: Synthesize unit/scale/... in event update")
Link: http://lkml.kernel.org/r/20181003212052.GA32371@krava
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
tools/perf/builtin-report.c | 1 +
tools/perf/util/evsel.c | 3 +++
2 files changed, 4 insertions(+)

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 76e12bcd1765..b2188e623e22 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -981,6 +981,7 @@ int cmd_report(int argc, const char **argv)
.id_index = perf_event__process_id_index,
.auxtrace_info = perf_event__process_auxtrace_info,
.auxtrace = perf_event__process_auxtrace,
+ .event_update = perf_event__process_event_update,
.feature = process_feature_event,
.ordered_events = true,
.ordering_requires_timestamps = true,
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 1a61628a1c12..e596ae358c4d 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1089,6 +1089,9 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts,
attr->exclude_user = 1;

+ if (evsel->own_cpus)
+ evsel->attr.read_format |= PERF_FORMAT_ID;
* Apply event specific term settings,
* it overloads any global configuration.