perf evsel: Provide meaningful warning when trying to use 'aux_output' on older kernels

Just like we do with the 'write_backwards' feature:

Before:

  # perf record -e {intel_pt/branch=0/,cycles/aux-output/ppp} uname
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cycles/aux-output/ppp).
  /bin/dmesg | grep -i perf may provide additional information.

  #

After:

  # perf record -e {intel_pt/branch=0/,cycles/aux-output/ppp} uname
  Error:
  The 'aux_output' feature is not supported, update the kernel.
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/n/tip-wgjsjroe1e150c0metgwmqwd@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 5da40511546b84bc746d37ac736410d115f530f4..0a33f7322eccbd338ac129b59a185ff0baf4b920 100644 (file)
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1738,7 +1738,8 @@ int evsel__open(struct evsel *evsel, struct perf_cpu_map *cpus,
        int pid = -1, err;
        enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE;
 
-       if (perf_missing_features.write_backward && evsel->core.attr.write_backward)
+       if ((perf_missing_features.write_backward && evsel->core.attr.write_backward) ||
+           (perf_missing_features.aux_output     && evsel->core.attr.aux_output))
                return -EINVAL;
 
        if (cpus == NULL) {
@@ -1912,7 +1913,11 @@ try_fallback:
         * Must probe features in the order they were added to the
         * perf_event_attr interface.
         */
-       if (!perf_missing_features.bpf_event && evsel->core.attr.bpf_event) {
+       if (!perf_missing_features.aux_output && evsel->core.attr.aux_output) {
+               perf_missing_features.aux_output = true;
+               pr_debug2("Kernel has no attr.aux_output support, bailing out\n");
+               goto out_close;
+       } else if (!perf_missing_features.bpf_event && evsel->core.attr.bpf_event) {
                perf_missing_features.bpf_event = true;
                pr_debug2("switching off bpf_event\n");
                goto fallback_missing_features;
@@ -2926,6 +2931,8 @@ int perf_evsel__open_strerror(struct evsel *evsel, struct target *target,
                        return scnprintf(msg, size, "clockid feature not supported.");
                if (perf_missing_features.clockid_wrong)
                        return scnprintf(msg, size, "wrong clockid (%d).", clockid);
+               if (perf_missing_features.aux_output)
+                       return scnprintf(msg, size, "The 'aux_output' feature is not supported, update the kernel.");
                break;
        default:
                break;

diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 8a316dd54cd0bd0a07b36a68e3d9a54067256936..9cd6e3ae479a719896a7907fc5148bcad553e537 100644 (file)
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -184,6 +184,7 @@ struct perf_missing_features {
        bool group_read;
        bool ksymbol;
        bool bpf_event;
+       bool aux_output;
 };
 
 extern struct perf_missing_features perf_missing_features;