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author | John Garry <john.garry@huawei.com> | 2021-06-10 22:32:59 +0800 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2021-06-19 10:06:46 -0300 |
commit | fc96ec4d5d4155c61cbafd49fb2dd403c899a9f4 (patch) | |
tree | 7e4b18060cef8e88b7d164c544db0eb2773e5cf0 /tools/perf | |
parent | 9ed13a17e38e0537e24d9b507645002bf8d0201f (diff) | |
download | linux-stable-fc96ec4d5d4155c61cbafd49fb2dd403c899a9f4.tar.gz linux-stable-fc96ec4d5d4155c61cbafd49fb2dd403c899a9f4.tar.bz2 linux-stable-fc96ec4d5d4155c61cbafd49fb2dd403c899a9f4.zip |
perf metricgroup: Fix find_evsel_group() event selector
The following command segfaults on my x86 broadwell:
$ ./perf stat -M frontend_bound,retiring,backend_bound,bad_speculation sleep 1
WARNING: grouped events cpus do not match, disabling group:
anon group { raw 0x10e }
anon group { raw 0x10e }
perf: util/evsel.c:1596: get_group_fd: Assertion `!(!leader->core.fd)' failed.
Aborted (core dumped)
The issue shows itself as a use-after-free in evlist__check_cpu_maps(),
whereby the leader of an event selector (evsel) has been deleted (yet we
still attempt to verify for an evsel).
Fundamentally the problem comes from metricgroup__setup_events() ->
find_evsel_group(), and has developed from the previous fix attempt in
commit 9c880c24cb0d ("perf metricgroup: Fix for metrics containing
duration_time").
The problem now is that the logic in checking if an evsel is in the same
group is subtly broken for the "cycles" event. For the "cycles" event,
the pmu_name is NULL; however the logic in find_evsel_group() may set an
event matched against "cycles" as used, when it should not be.
This leads to a condition where an evsel is set, yet its leader is not.
Fix the check for evsel pmu_name by not matching evsels when either has a
NULL pmu_name.
There is still a pre-existing metric issue whereby the ordering of the
metrics may break the 'stat' function, as discussed at:
https://lore.kernel.org/lkml/49c6fccb-b716-1bf0-18a6-cace1cdb66b9@huawei.com/
Fixes: 9c880c24cb0d ("perf metricgroup: Fix for metrics containing duration_time")
Signed-off-by: John Garry <john.garry@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> # On a Thinkpad T450S
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/1623335580-187317-2-git-send-email-john.garry@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
-rw-r--r-- | tools/perf/util/metricgroup.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c index 8336dd8e8098..c456fdeae06a 100644 --- a/tools/perf/util/metricgroup.c +++ b/tools/perf/util/metricgroup.c @@ -162,10 +162,10 @@ static bool contains_event(struct evsel **metric_events, int num_events, return false; } -static bool evsel_same_pmu(struct evsel *ev1, struct evsel *ev2) +static bool evsel_same_pmu_or_none(struct evsel *ev1, struct evsel *ev2) { if (!ev1->pmu_name || !ev2->pmu_name) - return false; + return true; return !strcmp(ev1->pmu_name, ev2->pmu_name); } @@ -288,7 +288,7 @@ static struct evsel *find_evsel_group(struct evlist *perf_evlist, */ if (!has_constraint && ev->leader != metric_events[i]->leader && - evsel_same_pmu(ev->leader, metric_events[i]->leader)) + evsel_same_pmu_or_none(ev->leader, metric_events[i]->leader)) break; if (!strcmp(metric_events[i]->name, ev->name)) { set_bit(ev->idx, evlist_used); |