perf report: Fix --task and --stat with pipe input

Current 'perf report' fails to process a pipe input when --task or
--stat options are used.  This is because they reset all the tool
callbacks and fails to find a matching event for a sample.

When pipe input is used, the event info is passed via ATTR records so it
needs to handle that operation.  Otherwise the following error occurs.
Note, -14 (= -EFAULT) comes from evlist__parse_sample():

  # perf record -a -o- sleep 1 | perf report -i- --stat
  Can't parse sample, err = -14
  0x271044 [0x38]: failed to process type: 9
  Error:
  failed to process sample
  #

Committer testing:

Before:

  $ perf record -o- sleep 1 | perf report -i- --stat
  Can't parse sample, err = -14
  [ perf record: Woken up 1 times to write data ]
  0x1350 [0x30]: failed to process type: 9
  Error:
  failed to process sample
  [ perf record: Captured and wrote 0.000 MB - ]
  $

After:

  $ perf record -o- sleep 1 | perf report -i- --stat
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]

  Aggregated stats:
             TOTAL events:         41
              COMM events:          2  ( 4.9%)
              EXIT events:          1  ( 2.4%)
            SAMPLE events:          9  (22.0%)
             MMAP2 events:          4  ( 9.8%)
              ATTR events:          1  ( 2.4%)
    FINISHED_ROUND events:          1  ( 2.4%)
        THREAD_MAP events:          1  ( 2.4%)
           CPU_MAP events:          1  ( 2.4%)
      EVENT_UPDATE events:          1  ( 2.4%)
         TIME_CONV events:          1  ( 2.4%)
           FEATURE events:         19  (46.3%)
  cycles:uhH stats:
            SAMPLE events:          9
  $

Fixes: a4a4d0a7 ("perf report: Add --stats option to display quick data statistics")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210630043058.1131295-1-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-report.c

@@ -729,9 +729,14 @@ static int count_sample_event(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
+static int process_attr(struct perf_tool *tool __maybe_unused,
+			union perf_event *event,
+			struct evlist **pevlist);
+
 static void stats_setup(struct report *rep)
 {
 	memset(&rep->tool, 0, sizeof(rep->tool));
+	rep->tool.attr = process_attr;
 	rep->tool.sample = count_sample_event;
 	rep->tool.no_warn = true;
 }
@@ -753,6 +758,7 @@ static void tasks_setup(struct report *rep)
 		rep->tool.mmap = perf_event__process_mmap;
 		rep->tool.mmap2 = perf_event__process_mmap2;
 	}
+	rep->tool.attr = process_attr;
 	rep->tool.comm = perf_event__process_comm;
 	rep->tool.exit = perf_event__process_exit;
 	rep->tool.fork = perf_event__process_fork;