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@cavium.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ganapatrao Kulkarni <gklkml16@gmail.com>
Cc: Jayachandran C <jnair@caviumnetworks.com>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <robert.richter@cavium.com>
Cc: Shaokun Zhang <zhangshaokun@hisilicon.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20171016183222.25750-6-ganapatrao.kulkarni@cavium.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 732ff57..8b7c151 100644 (file)
--- 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++];