perf record: Add finished init event

In preparation for recording sideband events in a virtual machine guest so
that they can be injected into a host perf.data file.

This is needed to enable injecting events after the initial synthesized
user events (that have an all zero id sample) but before regular events.

Committer notes:

Add entry about PERF_RECORD_FINISHED_INIT to
tools/perf/Documentation/perf.data-file-format.txt.

Committer testing:

Before:

  # perf report -D | grep FINISHED
  0 0x5910 [0x8]: PERF_RECORD_FINISHED_ROUND
    FINISHED_ROUND events:          1  ( 0.5%)
  #

After:

  # perf record -- sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.020 MB perf.data (7 samples) ]
  # perf report -D | grep FINISHED
  0 0x5068 [0x8]: PERF_RECORD_FINISHED_INIT: unhandled!
  0 0x5390 [0x8]: PERF_RECORD_FINISHED_ROUND
    FINISHED_ROUND events:          1  ( 0.5%)
     FINISHED_INIT events:          1  ( 0.5%)
  #

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20220610113316.6682-5-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 40dca1fba4e3..cf5c5379ceaa 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1388,6 +1388,11 @@ static struct perf_event_header finished_round_event = {
 	.type = PERF_RECORD_FINISHED_ROUND,
 };
 
+static struct perf_event_header finished_init_event = {
+	.size = sizeof(struct perf_event_header),
+	.type = PERF_RECORD_FINISHED_INIT,
+};
+
 static void record__adjust_affinity(struct record *rec, struct mmap *map)
 {
 	if (rec->opts.affinity != PERF_AFFINITY_SYS &&
@@ -1696,6 +1701,14 @@ static int record__synthesize_workload(struct record *rec, bool tail)
 	return err;
 }
 
+static int write_finished_init(struct record *rec, bool tail)
+{
+	if (rec->opts.tail_synthesize != tail)
+		return 0;
+
+	return record__write(rec, NULL, &finished_init_event, sizeof(finished_init_event));
+}
+
 static int record__synthesize(struct record *rec, bool tail);
 
 static int
@@ -1710,6 +1723,8 @@ record__switch_output(struct record *rec, bool at_exit)
 
 	record__aio_mmap_read_sync(rec);
 
+	write_finished_init(rec, true);
+
 	record__synthesize(rec, true);
 	if (target__none(&rec->opts.target))
 		record__synthesize_workload(rec, true);
@@ -1764,6 +1779,7 @@ record__switch_output(struct record *rec, bool at_exit)
 		 */
 		if (target__none(&rec->opts.target))
 			record__synthesize_workload(rec, false);
+		write_finished_init(rec, false);
 	}
 	return fd;
 }
@@ -2419,6 +2435,15 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 	trigger_ready(&auxtrace_snapshot_trigger);
 	trigger_ready(&switch_output_trigger);
 	perf_hooks__invoke_record_start();
+
+	/*
+	 * Must write FINISHED_INIT so it will be seen after all other
+	 * synthesized user events, but before any regular events.
+	 */
+	err = write_finished_init(rec, false);
+	if (err < 0)
+		goto out_child;
+
 	for (;;) {
 		unsigned long long hits = thread->samples;
 
@@ -2563,6 +2588,8 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 		fprintf(stderr, "[ perf record: Woken up %ld times to write data ]\n",
 			record__waking(rec));
 
+	write_finished_init(rec, true);
+
 	if (target__none(&rec->opts.target))
 		record__synthesize_workload(rec, true);