perf: add perf-inject builtin

Currently, perf 'live mode' writes build-ids at the end of the
session, which isn't actually useful for processing live mode events.

What would be better would be to have the build-ids sent before any of
the samples that reference them, which can be done by processing the
event stream and retrieving the build-ids on the first hit.  Doing
that in perf-record itself, however, is off-limits.

This patch introduces perf-inject, which does the same job while
leaving perf-record untouched.  Normal mode perf still records the
build-ids at the end of the session as it should, but for live mode,
perf-inject can be injected in between the record and report steps
e.g.:

perf record -o - ./hackbench 10 | perf inject -v -b | perf report -v -i -

perf-inject reads a perf-record event stream and repipes it to stdout.
At any point the processing code can inject other events into the
event stream - in this case build-ids (-b option) are read and
injected as needed into the event stream.

Build-ids are just the first user of perf-inject - potentially
anything that needs userspace processing to augment the trace stream
with additional information could make use of this facility.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1272696080-16435-3-git-send-email-tzanussi@gmail.com>
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 27 insertions, 8 deletions

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 2d1d97e..79da0e5 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -713,10 +713,18 @@ static int __event_process_build_id(struct build_id_event *bev,
 
 	dso = __dsos__findnew(head, filename);
 	if (dso != NULL) {
+		char sbuild_id[BUILD_ID_SIZE * 2 + 1];
+
 		dso__set_build_id(dso, &bev->build_id);
-			if (filename[0] == '[')
-				dso->kernel = dso_type;
-		}
+
+		if (filename[0] == '[')
+			dso->kernel = dso_type;
+
+		build_id__sprintf(dso->build_id, sizeof(dso->build_id),
+				  sbuild_id);
+		pr_debug("build id event received for %s: %s\n",
+			 dso->long_name, sbuild_id);
+	}
 
 	err = 0;
 out:
@@ -767,7 +775,7 @@ static int perf_file_section__process(struct perf_file_section *self,
 
 	switch (feat) {
 	case HEADER_TRACE_INFO:
-		trace_report(fd);
+		trace_report(fd, false);
 		break;
 
 	case HEADER_BUILD_ID:
@@ -782,12 +790,16 @@ static int perf_file_section__process(struct perf_file_section *self,
 }
 
 static int perf_file_header__read_pipe(struct perf_pipe_file_header *self,
-				       struct perf_header *ph, int fd)
+				       struct perf_header *ph, int fd,
+				       bool repipe)
 {
 	if (do_read(fd, self, sizeof(*self)) <= 0 ||
 	    memcmp(&self->magic, __perf_magic, sizeof(self->magic)))
 		return -1;
 
+	if (repipe && do_write(STDOUT_FILENO, self, sizeof(*self)) < 0)
+		return -1;
+
 	if (self->size != sizeof(*self)) {
 		u64 size = bswap_64(self->size);
 
@@ -805,7 +817,8 @@ static int perf_header__read_pipe(struct perf_session *session, int fd)
 	struct perf_header *self = &session->header;
 	struct perf_pipe_file_header f_header;
 
-	if (perf_file_header__read_pipe(&f_header, self, fd) < 0) {
+	if (perf_file_header__read_pipe(&f_header, self, fd,
+					session->repipe) < 0) {
 		pr_debug("incompatible file format\n");
 		return -EINVAL;
 	}
@@ -1096,12 +1109,17 @@ int event__process_tracing_data(event_t *self,
 	lseek(session->fd, offset + sizeof(struct tracing_data_event),
 	      SEEK_SET);
 
-	size_read = trace_report(session->fd);
+	size_read = trace_report(session->fd, session->repipe);
 
 	padding = ALIGN(size_read, sizeof(u64)) - size_read;
 
 	if (read(session->fd, buf, padding) < 0)
 		die("reading input file");
+	if (session->repipe) {
+		int retw = write(STDOUT_FILENO, buf, padding);
+		if (retw <= 0 || retw != padding)
+			die("repiping tracing data padding");
+	}
 
 	if (size_read + padding != size)
 		die("tracing data size mismatch");
@@ -1110,7 +1128,8 @@ int event__process_tracing_data(event_t *self,
 }
 
 int event__synthesize_build_id(struct dso *pos, u16 misc,
-			       event__handler_t process, struct machine *machine,
+			       event__handler_t process,
+			       struct machine *machine,
 			       struct perf_session *session)
 {
 	event_t ev;