[PATCH v1] perf arm: Workaround ARM PMUs cpu maps having offline cpus

From: Ian Rogers
Date: Fri Jun 07 2024 - 02:54:10 EST


When PMUs have a cpu map in the 'cpus' or 'cpumask' file, perf will
try to open events on those CPUs. ARM doesn't remove offline CPUs
meaning taking a CPU offline will cause perf commands to fail unless a
CPU map is passed on the command line.

More context in:
https://lore.kernel.org/lkml/20240603092812.46616-1-yangyicong@xxxxxxxxxx/

Reported-by: Yicong Yang <yangyicong@xxxxxxxxxx>
Closes: https://lore.kernel.org/lkml/20240603092812.46616-2-yangyicong@xxxxxxxxxx/
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
tools/perf/arch/arm/util/pmu.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/tools/perf/arch/arm/util/pmu.c b/tools/perf/arch/arm/util/pmu.c
index 8b7cb68ba1a8..6b544edbd3f6 100644
--- a/tools/perf/arch/arm/util/pmu.c
+++ b/tools/perf/arch/arm/util/pmu.c
@@ -11,12 +11,15 @@

#include "arm-spe.h"
#include "hisi-ptt.h"
+#include "../../../util/cpumap.h"
#include "../../../util/pmu.h"
#include "../../../util/cs-etm.h"
#include "../../arm64/util/mem-events.h"

-void perf_pmu__arch_init(struct perf_pmu *pmu __maybe_unused)
+void perf_pmu__arch_init(struct perf_pmu *pmu)
{
+ struct perf_cpu_map *intersect;
+
#ifdef HAVE_AUXTRACE_SUPPORT
if (!strcmp(pmu->name, CORESIGHT_ETM_PMU_NAME)) {
/* add ETM default config here */
@@ -33,6 +36,9 @@ void perf_pmu__arch_init(struct perf_pmu *pmu __maybe_unused)
pmu->selectable = true;
#endif
}
-
#endif
+ /* Workaround some ARM PMU's failing to correctly set CPU maps for online processors. */
+ intersect = perf_cpu_map__intersect(cpu_map__online(), pmu->cpus);
+ perf_cpu_map__put(pmu->cpus);
+ pmu->cpus = intersect;
}
--
2.45.2.505.gda0bf45e8d-goog