perf inject: Fix output from a file to a pipe

When the input is a regular file but the output is a pipe, it should
write a pipe header.  But just repiping would write a portion of the
existing header which is different in 'size' value.  So we need to
prevent it and write a new pipe header along with other information
like event attributes and features.

This can handle something like this:

  # perf record -a -B sleep 1

  # perf inject -b -i perf.data | perf report -i -

Factor out perf_event__synthesize_for_pipe() to be shared between perf
record and inject.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.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/20210719223153.1618812-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 58 insertions, 1 deletions

diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 35aa0c0f7cd9..a7e981b2d7de 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only 
 
+#include "util/cgroup.h"
+#include "util/data.h"
 #include "util/debug.h"
 #include "util/dso.h"
 #include "util/event.h"
@@ -16,7 +18,6 @@
 #include "util/synthetic-events.h"
 #include "util/target.h"
 #include "util/time-utils.h"
-#include "util/cgroup.h"
 #include <linux/bitops.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
@@ -2179,3 +2180,53 @@ int perf_event__synthesize_features(struct perf_tool *tool, struct perf_session
 	free(ff.buf);
 	return ret;
 }
+
+int perf_event__synthesize_for_pipe(struct perf_tool *tool,
+				    struct perf_session *session,
+				    struct perf_data *data,
+				    perf_event__handler_t process)
+{
+	int err;
+	int ret = 0;
+	struct evlist *evlist = session->evlist;
+
+	/*
+	 * We need to synthesize events first, because some
+	 * features works on top of them (on report side).
+	 */
+	err = perf_event__synthesize_attrs(tool, evlist, process);
+	if (err < 0) {
+		pr_err("Couldn't synthesize attrs.\n");
+		return err;
+	}
+	ret += err;
+
+	err = perf_event__synthesize_features(tool, session, evlist, process);
+	if (err < 0) {
+		pr_err("Couldn't synthesize features.\n");
+		return err;
+	}
+	ret += err;
+
+	if (have_tracepoints(&evlist->core.entries)) {
+		int fd = perf_data__fd(data);
+
+		/*
+		 * FIXME err <= 0 here actually means that
+		 * there were no tracepoints so its not really
+		 * an error, just that we don't need to
+		 * synthesize anything.  We really have to
+		 * return this more properly and also
+		 * propagate errors that now are calling die()
+		 */
+		err = perf_event__synthesize_tracing_data(tool,	fd, evlist,
+							  process);
+		if (err <= 0) {
+			pr_err("Couldn't record tracing data.\n");
+			return err;
+		}
+		ret += err;
+	}
+
+	return ret;
+}
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index e7a3e9589738..c845e2b9b444 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -14,6 +14,7 @@ struct evsel;
 struct machine;
 struct perf_counts_values;
 struct perf_cpu_map;
+struct perf_data;
 struct perf_event_attr;
 struct perf_event_mmap_page;
 struct perf_sample;
@@ -101,4 +102,9 @@ static inline int perf_event__synthesize_bpf_events(struct perf_session *session
 }
 #endif // HAVE_LIBBPF_SUPPORT
 
+int perf_event__synthesize_for_pipe(struct perf_tool *tool,
+				    struct perf_session *session,
+				    struct perf_data *data,
+				    perf_event__handler_t process);
+
 #endif // __PERF_SYNTHETIC_EVENTS_H