perf symbols: Synthesize anonymous mmap events
Anton Blanchard [Mon, 29 Aug 2011 23:15:06 +0000 (09:15 +1000)]
perf_event__synthesize_mmap_events does not create anonymous mmap events
even though the kernel does. As a result an already running application
with dynamically created code will not get profiled - all samples end up
in the unknown bucket.

This patch skips any entries with '[' in the name to avoid adding events
for special regions (eg the vsyscall page). All other executable mmaps
are assumed to be anonymous and an event is synthesized.

Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Link: http://lkml.kernel.org/r/20110830091506.60b51fe8@kryten
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/event.c

index 3c1b8a6..437f8ca 100644 (file)
@@ -169,12 +169,17 @@ static int perf_event__synthesize_mmap_events(union perf_event *event,
                        continue;
                pbf += n + 3;
                if (*pbf == 'x') { /* vm_exec */
+                       char anonstr[] = "//anon\n";
                        char *execname = strchr(bf, '/');
 
                        /* Catch VDSO */
                        if (execname == NULL)
                                execname = strstr(bf, "[vdso]");
 
+                       /* Catch anonymous mmaps */
+                       if ((execname == NULL) && !strstr(bf, "["))
+                               execname = anonstr;
+
                        if (execname == NULL)
                                continue;