From: John Garry john.garry@huawei.com
[ Upstream commit fc96ec4d5d4155c61cbafd49fb2dd403c899a9f4 ]
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@hu... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/metricgroup.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c index 26c990e32378..1af71ac1cc68 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);