perf evsel: Improve AMD IBS (Instruction-Based Sampling) error handling messages

Improve the error message returned on failed perf_event_open() on AMD
systems when using IBS (Instruction-Based Sampling).

Output of executing 'perf record -e ibs_op// true' as a non root user
BEFORE this patch (perf will add the 'u' modifier at the end to exclude
kernel/hypervisor sampling):

  The sys_perf_event_open() syscall returned with 22 (Invalid argument)for event (ibs_op//u).
  /bin/dmesg | grep -i perf may provide additional information.

Output after:

  AMD IBS can't exclude kernel events.  Try running at a higher privilege level.

Output of executing 'sudo perf record -e ibs_op// true' BEFORE this patch:

  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (ibs_op//).
  /bin/dmesg | grep -i perf may provide additional information.

Output after:

  Error:
  Invalid event (ibs_op//) in per-thread mode, enable system wide with '-a'.

Folowing the suggestion:

  $ sudo perf record -a -e ibs_op// true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 1.664 MB perf.data (194 samples) ]
  $

Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: João Martins <joao.m.martins@oracle.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20220322221517.2510440-12-eranian@google.com
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 5ecf8f8..2a1729e 100644 (file)
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2847,9 +2847,23 @@ static bool find_process(const char *name)
        return ret ? false : true;
 }
 
+static bool is_amd(const char *arch, const char *cpuid)
+{
+       return arch && !strcmp("x86", arch) && cpuid && strstarts(cpuid, "AuthenticAMD");
+}
+
+static bool is_amd_ibs(struct evsel *evsel)
+{
+       return evsel->core.attr.precise_ip
+           || (evsel->pmu_name && !strncmp(evsel->pmu_name, "ibs", 3));
+}
+
 int evsel__open_strerror(struct evsel *evsel, struct target *target,
                         int err, char *msg, size_t size)
 {
+       struct perf_env *env = evsel__env(evsel);
+       const char *arch = perf_env__arch(env);
+       const char *cpuid = perf_env__cpuid(env);
        char sbuf[STRERR_BUFSIZE];
        int printed = 0, enforced = 0;
 
@@ -2953,6 +2967,17 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
                        return scnprintf(msg, size,
        "Invalid event (%s) in per-thread mode, enable system wide with '-a'.",
                                        evsel__name(evsel));
+               if (is_amd(arch, cpuid)) {
+                       if (is_amd_ibs(evsel)) {
+                               if (evsel->core.attr.exclude_kernel)
+                                       return scnprintf(msg, size,
+       "AMD IBS can't exclude kernel events.  Try running at a higher privilege level.");
+                               if (!evsel->core.system_wide)
+                                       return scnprintf(msg, size,
+       "AMD IBS may only be available in system-wide/per-cpu mode.  Try using -a, or -C and workload affinity");
+                       }
+               }
+
                break;
        case ENODATA:
                return scnprintf(msg, size, "Cannot collect data source with the load latency event alone. "