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 <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Kang Minchul <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Richter <[e-mail]>
Cc: Xing Zhengjun <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/pfm.c

···
 
 	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);