From: Ian Rogers <irogers@google.com>
Date: Wed, 6 Sep 2023 23:44:16 +0000 (-0700)
Subject: perf list pfm: Retry supported test with exclude_kernel
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=6bd8c2ea6b93aabcb4a046ca7a6ad353b574d0a3;p=linux.git

perf list pfm: Retry supported test with exclude_kernel

With paranoia set at 2 evsel__open will fail with EACCES for non-root
users. To avoid this stopping libpfm4 events from being printed, retry
with exclude_kernel enabled - copying the regular is_event_supported
test.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kang Minchul <tegongkang@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20230906234416.3472339-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

diff --git a/tools/perf/util/pfm.c b/tools/perf/util/pfm.c
index 862e4a689868b..5ccfe4b64cdfe 100644
--- a/tools/perf/util/pfm.c
+++ b/tools/perf/util/pfm.c
@@ -145,7 +145,20 @@ static bool is_libpfm_event_supported(const char *name, struct perf_cpu_map *cpu
 
 	evsel->is_libpfm_event = true;
 
-	if (evsel__open(evsel, cpus, threads) < 0)
+	ret = evsel__open(evsel, cpus, threads);
+	if (ret == -EACCES) {
+		/*
+		 * This happens if the paranoid value
+		 * /proc/sys/kernel/perf_event_paranoid is set to 2
+		 * Re-run with exclude_kernel set; we don't do that
+		 * by default as some ARM machines do not support it.
+		 *
+		 */
+		evsel->core.attr.exclude_kernel = 1;
+		ret = evsel__open(evsel, cpus, threads);
+
+	}
+	if (ret < 0)
 		result = false;
 
 	evsel__close(evsel);