perf tools: Stop copying kallsyms into the perf.data file header

Since we now ask libtraceevent, the only user of this payload, to use
perf's symbol resolution routines, there is no need to carry about
~4.5MB per perf.data when we can get it from one of the places the perf
symbol resolution looks for that symtab (debuginfo, ~/.debug/,
/proc/kallsyms, --symfs, etc), using the kernel and modules build-ids to
make sure the right table is used.

Acked-by: David Ahern <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Steven Rostedt <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 8 insertions, 14 deletions

diff --git a/tools/perf/util/trace-event-info.c b/tools/perf/util/trace-event-info.c
index eb72716017ac..22245986e59e 100644
--- a/tools/perf/util/trace-event-info.c
+++ b/tools/perf/util/trace-event-info.c
@@ -341,20 +341,14 @@ out:
 
 static int record_proc_kallsyms(void)
 {
-	unsigned int size;
-	const char *path = "/proc/kallsyms";
-	struct stat st;
-	int ret, err = 0;
-
-	ret = stat(path, &st);
-	if (ret < 0) {
-		/* not found */
-		size = 0;
-		if (write(output_fd, &size, 4) != 4)
-			err = -EIO;
-		return err;
-	}
-	return record_file(path, 4);
+	unsigned long long size = 0;
+	/*
+	 * Just to keep older perf.data file parsers happy, record a zero
+	 * sized kallsyms file, i.e. do the same thing that was done when
+	 * /proc/kallsyms (or something specified via --kallsyms, in a
+	 * different path) couldn't be read.
+	 */
+	return write(output_fd, &size, 4) != 4 ? -EIO : 0;
 }
 
 static int record_ftrace_printk(void)