perf evlist: Allow reusing the side band thread for more purposes

I.e. so far we had just one event in that side band thread, a dummy one
with attr.bpf_event set, so that 'perf record' can go ahead and ask the
kernel for further information about BPF programs being loaded.

Allow for more than one event to be there, so that we can use it as
well for the upcoming --switch-output-event feature.

Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Link: http://lore.kernel.org/lkml/20200429131106.27974-6-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/tools/perf/util/sideband_evlist.c b/tools/perf/util/sideband_evlist.c
index 073d201bb6ea..1d6f470d64c4 100644
--- a/tools/perf/util/sideband_evlist.c
+++ b/tools/perf/util/sideband_evlist.c
@@ -4,6 +4,7 @@
 #include "util/evlist.h"
 #include "util/evsel.h"
 #include "util/mmap.h"
+#include "util/perf_api_probe.h"
 #include <perf/mmap.h>
 #include <linux/perf_event.h>
 #include <limits.h>
@@ -80,6 +81,19 @@ static void *perf_evlist__poll_thread(void *arg)
 	return NULL;
 }
 
+void evlist__set_cb(struct evlist *evlist, perf_evsel__sb_cb_t cb, void *data)
+{
+	struct evsel *evsel;
+
+	evlist__for_each_entry(evlist, evsel) {
+		evsel->core.attr.sample_id_all    = 1;
+		evsel->core.attr.watermark        = 1;
+		evsel->core.attr.wakeup_watermark = 1;
+		evsel->side_band.cb   = cb;
+		evsel->side_band.data = data;
+      }
+}
+
 int perf_evlist__start_sb_thread(struct evlist *evlist, struct target *target)
 {
 	struct evsel *counter;
@@ -90,6 +104,15 @@ int perf_evlist__start_sb_thread(struct evlist *evlist, struct target *target)
 	if (perf_evlist__create_maps(evlist, target))
 		goto out_delete_evlist;
 
+	if (evlist->core.nr_entries > 1) {
+		bool can_sample_identifier = perf_can_sample_identifier();
+
+		evlist__for_each_entry(evlist, counter)
+			perf_evsel__set_sample_id(counter, can_sample_identifier);
+
+		perf_evlist__set_id_pos(evlist);
+	}
+
 	evlist__for_each_entry(evlist, counter) {
 		if (evsel__open(counter, evlist->core.cpus, evlist->core.threads) < 0)
 			goto out_delete_evlist;