perf evsel: Fixes topdown events in a weak group for the hybrid platform

perf evsel: Fixes topdown events in a weak group for the hybrid platform

The patch ("perf evlist: Keep topdown counters in weak group") fixes the
perf metrics topdown event issue when the topdown events are in a weak
group on a non-hybrid platform. However, it doesn't work for the hybrid
platform.

  $./perf stat -e '{cpu_core/slots/,cpu_core/topdown-bad-spec/,
  cpu_core/topdown-be-bound/,cpu_core/topdown-fe-bound/,
  cpu_core/topdown-retiring/,cpu_core/branch-instructions/,
  cpu_core/branch-misses/,cpu_core/bus-cycles/,cpu_core/cache-misses/,
  cpu_core/cache-references/,cpu_core/cpu-cycles/,cpu_core/instructions/,
  cpu_core/mem-loads/,cpu_core/mem-stores/,cpu_core/ref-cycles/,
  cpu_core/cache-misses/,cpu_core/cache-references/}:W' -a sleep 1

  Performance counter stats for 'system wide':

       751,765,068      cpu_core/slots/                        (84.07%)
   <not supported>      cpu_core/topdown-bad-spec/
   <not supported>      cpu_core/topdown-be-bound/
   <not supported>      cpu_core/topdown-fe-bound/
   <not supported>      cpu_core/topdown-retiring/
        12,398,197      cpu_core/branch-instructions/          (84.07%)
         1,054,218      cpu_core/branch-misses/                (84.24%)
       539,764,637      cpu_core/bus-cycles/                   (84.64%)
            14,683      cpu_core/cache-misses/                 (84.87%)
         7,277,809      cpu_core/cache-references/             (77.30%)
       222,299,439      cpu_core/cpu-cycles/                   (77.28%)
        63,661,714      cpu_core/instructions/                 (84.85%)
                 0      cpu_core/mem-loads/                    (77.29%)
        12,271,725      cpu_core/mem-stores/                   (77.30%)
       542,241,102      cpu_core/ref-cycles/                   (84.85%)
             8,854      cpu_core/cache-misses/                 (76.71%)
         7,179,013      cpu_core/cache-references/             (76.31%)

         1.003245250 seconds time elapsed

A hybrid platform has a different PMU name for the core PMUs, while
the current perf hard code the PMU name "cpu".

The evsel->pmu_name can be used to replace the "cpu" to fix the issue.
For a hybrid platform, the pmu_name must be non-NULL. Because there are
at least two core PMUs. The PMU has to be specified.
For a non-hybrid platform, the pmu_name may be NULL. Because there is
only one core PMU, "cpu". For a NULL pmu_name, we can safely assume that
it is a "cpu" PMU.

In case other PMUs also define the "slots" event, checking the PMU type
as well.

With the patch,

  $ perf stat -e '{cpu_core/slots/,cpu_core/topdown-bad-spec/,
  cpu_core/topdown-be-bound/,cpu_core/topdown-fe-bound/,
  cpu_core/topdown-retiring/,cpu_core/branch-instructions/,
  cpu_core/branch-misses/,cpu_core/bus-cycles/,cpu_core/cache-misses/,
  cpu_core/cache-references/,cpu_core/cpu-cycles/,cpu_core/instructions/,
  cpu_core/mem-loads/,cpu_core/mem-stores/,cpu_core/ref-cycles/,
  cpu_core/cache-misses/,cpu_core/cache-references/}:W' -a sleep 1

  Performance counter stats for 'system wide':

     766,620,266   cpu_core/slots/                                        (84.06%)
      73,172,129   cpu_core/topdown-bad-spec/ #    9.5% bad speculation   (84.06%)
     193,443,341   cpu_core/topdown-be-bound/ #    25.0% backend bound    (84.06%)
     403,940,929   cpu_core/topdown-fe-bound/ #    52.3% frontend bound   (84.06%)
     102,070,237   cpu_core/topdown-retiring/ #    13.2% retiring         (84.06%)
      12,364,429   cpu_core/branch-instructions/                          (84.03%)
       1,080,124   cpu_core/branch-misses/                                (84.24%)
     564,120,383   cpu_core/bus-cycles/                                   (84.65%)
          36,979   cpu_core/cache-misses/                                 (84.86%)
       7,298,094   cpu_core/cache-references/                             (77.30%)
     227,174,372   cpu_core/cpu-cycles/                                   (77.31%)
      63,886,523   cpu_core/instructions/                                 (84.87%)
               0   cpu_core/mem-loads/                                    (77.31%)
      12,208,782   cpu_core/mem-stores/                                   (77.31%)
     566,409,738   cpu_core/ref-cycles/                                   (84.87%)
          23,118   cpu_core/cache-misses/                                 (76.71%)
       7,212,602   cpu_core/cache-references/                             (76.29%)

       1.003228667 seconds time elapsed

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20220518143900.1493980-2-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>