From: James Clark james.clark@arm.com
mainline inclusion from mainline-v5.18-rc1 commit 8f431a28696d27e3370ebd1a5fd1681a8c773a8e category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8EC9K CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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EOPNOTSUPP is a possible return value when branch stacks are requested but they aren't enabled in the kernel or hardware. It's also returned if they aren't supported on the specific event type. The currently printed error message about sampling/overflow-interrupts is not correct in this case.
Add a check for branch stacks before sample_period is checked because sample_period is also set (to the default value) when using branch stacks.
Before this change (when branch stacks aren't supported):
perf record -j any Error: cycles: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'
After this change:
perf record -j any Error: cycles: PMU Hardware or event type doesn't support branch stack sampling.
Signed-off-by: James Clark james.clark@arm.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: German Gomez german.gomez@arm.com Cc: Jiri Olsa jolsa@kernel.org Cc: Leo Yan leo.yan@linaro.org Cc: Mark Rutland mark.rutland@arm.com Cc: Namhyung Kim namhyung@kernel.org Link: https://lore.kernel.org/r/20220307171917.2555829-2-james.clark@arm.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Junhao He hejunhao3@huawei.com --- tools/perf/util/evsel.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 1a1cbd16d76d..9fd9c3cb2330 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -2659,6 +2659,10 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target, "No such device - did you specify an out-of-range profile CPU?"); break; case EOPNOTSUPP: + if (evsel->core.attr.sample_type & PERF_SAMPLE_BRANCH_STACK) + return scnprintf(msg, size, + "%s: PMU Hardware or event type doesn't support branch stack sampling.", + evsel__name(evsel)); if (evsel->core.attr.aux_output) return scnprintf(msg, size, "%s: PMU Hardware doesn't support 'aux_output' feature",