[tip:perf/core] perf pmu: Add check for valid cpuid in perf_pmu__find_map()

[tip-bot for Ganapatrao Kulkarni]

Commit-ID:  de3d0f12be476271d03f1ddb5a7c241c2f07f126
Gitweb:     https://git.kernel.org/tip/de3d0f12be476271d03f1ddb5a7c241c2f07f126
Author:     Ganapatrao Kulkarni <ganapatrao.kulkarni@xxxxxxxxxx>
AuthorDate: Tue, 17 Oct 2017 00:02:22 +0530
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 5 Dec 2017 15:43:51 -0300

perf pmu: Add check for valid cpuid in perf_pmu__find_map()

On some platforms(arm/arm64) which uses cpus map to get corresponding
cpuid string, cpuid can be NULL for PMUs other than CORE PMUs.  Adding
check for NULL cpuid in function perf_pmu__find_map to avoid
segmentation fault.

Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Ganapatrao Kulkarni <gklkml16@xxxxxxxxx>
Cc: Jayachandran C <jnair@xxxxxxxxxxxxxxxxxx>
Cc: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Robert Richter <robert.richter@xxxxxxxxxx>
Cc: Shaokun Zhang <zhangshaokun@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20171016183222.25750-6-ganapatrao.kulkarni@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/pmu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 732ff57..8b7c151 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -601,6 +601,12 @@ struct pmu_events_map *perf_pmu__find_map(struct perf_pmu *pmu)
 	char *cpuid = perf_pmu__getcpuid(pmu);
 	int i;
 
+	/* on some platforms which uses cpus map, cpuid can be NULL for
+	 * PMUs other than CORE PMUs.
+	 */
+	if (!cpuid)
+		return NULL;
+
 	i = 0;
 	for (;;) {
 		map = &pmu_events_map[i++];