linux-kernel - [PATCH perf/urgent] perf tools: Fix crash on synthesizing the unit

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Message-Id: <20181112130012.5424-1-jolsa@kernel.org>
Date:   Mon, 12 Nov 2018 14:00:12 +0100
From:   Jiri Olsa <jolsa@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Adam Lee <leeadamrobert@...il.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [PATCH perf/urgent] perf tools: Fix crash on synthesizing the unit

Adam reported a record command crash for simple session like:
  $ perf record -e cpu-clock ls

with following backtrace:

  Program received signal SIGSEGV, Segmentation fault.
  3543            ev = event_update_event__new(size + 1, PERF_EVENT_UPDATE__UNIT, evsel->id[0]);
  (gdb) bt
  #0  perf_event__synthesize_event_update_unit
  #1  0x000000000051e469 in perf_event__synthesize_extra_attr
  #2  0x00000000004445cb in record__synthesize
  #3  0x0000000000444bc5 in __cmd_record
  ...

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 unit defined.

Reflecting possible read_format ID bit in the attr tests.

Cc: Adam Lee <leeadamrobert@...il.com>
Reported-by: Yongxin Liu <yongxin.liu@...look.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201477
Fixes: bfd8f72c2778 ("perf record: Synthesize unit/scale/... in event update")
Link: http://lkml.kernel.org/n/tip-hmt7oavo3w97btxl8sfq8n0i@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/perf/tests/attr/base-record | 2 +-
 tools/perf/util/evsel.c           | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/attr/base-record b/tools/perf/tests/attr/base-record
index 37940665f736..efd0157b9d22 100644
--- a/tools/perf/tests/attr/base-record
+++ b/tools/perf/tests/attr/base-record
@@ -9,7 +9,7 @@ size=112
 config=0
 sample_period=*
 sample_type=263
-read_format=0
+read_format=0|4
 disabled=1
 inherit=1
 pinned=0
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index d37bb1566cd9..dbc0466db368 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1092,7 +1092,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts,
 		attr->exclude_user   = 1;
 	}
 
-	if (evsel->own_cpus)
+	if (evsel->own_cpus || evsel->unit)
 		evsel->attr.read_format |= PERF_FORMAT_ID;
 
 	/*
-- 
2.17.2