[RFC PATCH] perf stat: Separate bperf from bpf_profiler

[Dmitrii Dolgov <9erthalion6@gmail.com>]

It seems that perf stat -b <prog id> doesn't produce any results:

    $ perf stat -e cycles -b 4 -I 10000 -vvv
    Control descriptor is not initialized
    cycles: 0 0 0
                time        counts unit      events
	10.007641640    <not supported>      cycles

Looks like this happens because fentry/fexit progs are getting loaded, but the
corresponding perf event is not enabled and not added into the events bpf map.
I think there is some mixing up between two type of bpf support, one for bperf
and one for bpf_profiler. Both are identified via evsel__is_bpf, based on which
perf events are enabled, but for the latter (bpf_profiler) a perf event is
required. Using evsel__is_bperf to check only bperf produces expected results:

    $ perf stat -e cycles -b 4 -I 10000 -vvv
    Control descriptor is not initialized
    ------------------------------------------------------------
    perf_event_attr:
      size                             136
      sample_type                      IDENTIFIER
      read_format                      TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
      disabled                         1
      exclude_guest                    1
    ------------------------------------------------------------
    sys_perf_event_open: pid -1  cpu 0  group_fd -1  flags 0x8 = 3
    ------------------------------------------------------------
    [...perf_event_attr for other CPUs...]
    ------------------------------------------------------------
    cycles: 309426 169009 169009
		time             counts unit events
	10.010091271             309426      cycles

The final numbers correspond (at least in the level of magnitude) to the
same metric obtained via bpftool.

Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com>
---
 tools/perf/builtin-stat.c | 4 ++--
 tools/perf/util/evsel.h   | 5 +++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index d3cbee7460f..23b8d684ca6 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -712,7 +712,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 		counter->reset_group = false;
 		if (bpf_counter__load(counter, &target))
 			return -1;
-		if (!evsel__is_bpf(counter))
+		if (!(evsel__is_bperf(counter)))
 			all_counters_use_bpf = false;
 	}
 
@@ -728,7 +728,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 
 		if (counter->reset_group || counter->errored)
 			continue;
-		if (evsel__is_bpf(counter))
+		if (evsel__is_bperf(counter))
 			continue;
 try_again:
 		if (create_perf_stat_counter(counter, &stat_config, &target,
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 68072ec655c..f0aa17dcf3d 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -269,6 +269,11 @@ static inline bool evsel__is_bpf(struct evsel *evsel)
 	return evsel->bpf_counter_ops != NULL;
 }
 
+static inline bool evsel__is_bperf(struct evsel *evsel)
+{
+	return evsel->bpf_counter_ops != NULL && list_empty(&evsel->bpf_counter_list);
+}
+
 #define EVSEL__MAX_ALIASES 8
 
 extern const char *const evsel__hw_cache[PERF_COUNT_HW_CACHE_MAX][EVSEL__MAX_ALIASES];
-- 
2.32.0