[PATCH AUTOSEL 4.19 204/206] perf parse-events: Use strcmp() to compare the PMU name

From: Sasha Levin
Date: Thu Sep 17 2020 - 22:12:36 EST

From: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>

[ Upstream commit 8510895bafdbf7c4dd24c22946d925691135c2b2 ]

A big uncore event group is split into multiple small groups which only
include the uncore events from the same PMU. This has been supported in
the commit 3cdc5c2cb924a ("perf parse-events: Handle uncore event
aliases in small groups properly").

If the event's PMU name starts to repeat, it must be a new event.
That can be used to distinguish the leader from other members.
But now it only compares the pointer of pmu_name
(leader->pmu_name == evsel->pmu_name).

If we use "perf stat -M LLC_MISSES.PCIE_WRITE -a" on cascadelakex,
the event list is:

evsel->name evsel->pmu_name
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_4 (as leader)
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_2
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_0
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_5
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_3
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_1
unc_iio_data_req_of_cpu.mem_write.part1 uncore_iio_4

For the event "unc_iio_data_req_of_cpu.mem_write.part1" with
"uncore_iio_4", it should be the event from PMU "uncore_iio_4".
It's not a new leader for this PMU.

But if we use "(leader->pmu_name == evsel->pmu_name)", the check
would be failed and the event is stored to leaders[] as a new
PMU leader.

So this patch uses strcmp to compare the PMU name between events.

Fixes: d4953f7ef1a2 ("perf parse-events: Fix 3 use after frees found with clang ASAN")
Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Jin Yao <yao.jin@xxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/20200430003618.17002-1-yao.jin@xxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
tools/perf/util/parse-events.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 426f1984c143e..5ab5c69f50500 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1423,12 +1423,11 @@ parse_events__set_leader_for_uncore_aliase(char *name, struct list_head *list,
* event. That can be used to distinguish the leader from
* other members, even they have the same event name.
- if ((leader != evsel) && (leader->pmu_name == evsel->pmu_name)) {
+ if ((leader != evsel) &&
+ !strcmp(leader->pmu_name, evsel->pmu_name)) {
is_leader = false;
- /* The name is always alias name */
- WARN_ON(strcmp(leader->name, evsel->name));

/* Store the leader event for each PMU */
leaders[nr_pmu++] = (uintptr_t) evsel;