Commit 8a92605d authored Sep 16, 2022 by Namhyung Kim Committed by Arnaldo Carvalho de Melo Sep 21, 2022

perf stat: Use evsel->core.cpus to iterate cpus in BPF cgroup counters



If it mixes core and uncore events, each evsel would have different cpu map.
But it assumed they are same with evlist's all_cpus and accessed by the same
index.  This resulted in a crash like below.

  $ perf stat -a --bpf-counters --for-each_cgroup ^. -e cycles,imc/cas_count_read/ sleep 1
  Segmentation fault

While it's not recommended to use uncore events for cgroup aggregation, it
should not crash.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20220916184132.1161506-4-namhyung@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 3da35231

tools/perf/util/bpf_counter_cgroup.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -115,14 +115,14 @@ static int bperf_load_program(struct evlist *evlist)
		evsel->cgrp = NULL;

		/* open single copy of the events w/o cgroup */
		err = evsel__open_per_cpu(evsel, evlist->core.all_cpus, -1);
		err = evsel__open_per_cpu(evsel, evsel->core.cpus, -1);
		if (err) {
		pr_err("Failed to open first cgroup events\n");
		goto out;
		}

		map_fd = bpf_map__fd(skel->maps.events);
		perf_cpu_map__for_each_cpu(cpu, j, evlist->core.all_cpus) {
		perf_cpu_map__for_each_cpu(cpu, j, evsel->core.cpus) {
		int fd = FD(evsel, j);
		__u32 idx = evsel->core.idx * total_cpus + cpu.cpu;

		@@ -269,7 +269,7 @@ static int bperf_cgrp__read(struct evsel *evsel)
		goto out;
		}

		perf_cpu_map__for_each_cpu(cpu, i, evlist->core.all_cpus) {
		perf_cpu_map__for_each_cpu(cpu, i, evsel->core.cpus) {
		counts = perf_counts(evsel->counts, i, 0);
		counts->val = values[cpu.cpu].counter;
		counts->ena = values[cpu.cpu].enabled;