perf symbols: Synthesize anonymous mmap events

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 <[email protected]>
Cc: Eric B Munson <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Pekka Enberg <[email protected]>
Link: http://lkml.kernel.org/r/20110830091506.60b51fe8@kryten
Signed-off-by: Anton Blanchard <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/perf/util/event.c

@@ -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;