perf_counter: Synthesize VDSO mmap event

perf record synthesizes mmap events for the running process.
Right now it just catches file mappings, but we can check for
the vdso symbol and add that too.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090716104817.517264409@samba.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

tools/perf/builtin-record.c

@@ -313,6 +313,10 @@ static void pid_synthesize_mmap_samples(pid_t pid)
 		if (*pbf == 'x') { /* vm_exec */
 			char *execname = strchr(bf, '/');
 
+			/* Catch VDSO */
+			if (execname == NULL)
+				execname = strstr(bf, "[vdso]");
+
 			if (execname == NULL)
 				continue;