1 files changed, 148 insertions, 0 deletions
diff --git a/tools/perf/util/sideband_evlist.c b/tools/perf/util/sideband_evlist.c
new file mode 100644
index 000000000..ded9ced02
--- /dev/null
+++ b/tools/perf/util/sideband_evlist.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "util/debug.h"
+#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>
+#include <pthread.h>
+#include <sched.h>
+#include <stdbool.h>
+
+int perf_evlist__add_sb_event(struct evlist *evlist, struct perf_event_attr *attr,
+			      evsel__sb_cb_t cb, void *data)
+{
+	struct evsel *evsel;
+
+	if (!attr->sample_id_all) {
+		pr_warning("enabling sample_id_all for all side band events\n");
+		attr->sample_id_all = 1;
+	}
+
+	evsel = evsel__new_idx(attr, evlist->core.nr_entries);
+	if (!evsel)
+		return -1;
+
+	evsel->side_band.cb = cb;
+	evsel->side_band.data = data;
+	evlist__add(evlist, evsel);
+	return 0;
+}
+
+static void *perf_evlist__poll_thread(void *arg)
+{
+	struct evlist *evlist = arg;
+	bool draining = false;
+	int i, done = 0;
+	/*
+	 * In order to read symbols from other namespaces perf to needs to call
+	 * setns(2).  This isn't permitted if the struct_fs has multiple users.
+	 * unshare(2) the fs so that we may continue to setns into namespaces
+	 * that we're observing when, for instance, reading the build-ids at
+	 * the end of a 'perf record' session.
+	 */
+	unshare(CLONE_FS);
+
+	while (!done) {
+		bool got_data = false;
+
+		if (evlist->thread.done)
+			draining = true;
+
+		if (!draining)
+			evlist__poll(evlist, 1000);
+
+		for (i = 0; i < evlist->core.nr_mmaps; i++) {
+			struct mmap *map = &evlist->mmap[i];
+			union perf_event *event;
+
+			if (perf_mmap__read_init(&map->core))
+				continue;
+			while ((event = perf_mmap__read_event(&map->core)) != NULL) {
+				struct evsel *evsel = perf_evlist__event2evsel(evlist, event);
+
+				if (evsel && evsel->side_band.cb)
+					evsel->side_band.cb(event, evsel->side_band.data);
+				else
+					pr_warning("cannot locate proper evsel for the side band event\n");
+
+				perf_mmap__consume(&map->core);
+				got_data = true;
+			}
+			perf_mmap__read_done(&map->core);
+		}
+
+		if (draining && !got_data)
+			break;
+	}
+	return NULL;
+}
+
+void evlist__set_cb(struct evlist *evlist, 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;
+
+	if (!evlist)
+		return 0;
+
+	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)
+			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;
+	}
+
+	if (evlist__mmap(evlist, UINT_MAX))
+		goto out_delete_evlist;
+
+	evlist__for_each_entry(evlist, counter) {
+		if (evsel__enable(counter))
+			goto out_delete_evlist;
+	}
+
+	evlist->thread.done = 0;
+	if (pthread_create(&evlist->thread.th, NULL, perf_evlist__poll_thread, evlist))
+		goto out_delete_evlist;
+
+	return 0;
+
+out_delete_evlist:
+	evlist__delete(evlist);
+	evlist = NULL;
+	return -1;
+}
+
+void perf_evlist__stop_sb_thread(struct evlist *evlist)
+{
+	if (!evlist)
+		return;
+	evlist->thread.done = 1;
+	pthread_join(evlist->thread.th, NULL);
+	evlist__delete(evlist);
+}