perf: Add vm_ops->name call for mmap event name retrieval

The following patch added another way to get mmap name: 78d683e8
("mm, fs: Add vm_ops->name as an alternative to arch_vma_name")

The vdso vma mapping already switch to this and we no longer get vdso
name via arch_vma_name function. Adding this way to the perf mmap
event name retrieval code.

Caught this via perf test:

  $ sudo ./perf test -v 7
   7: Validate PERF_RECORD_* events & perf_sample fields     :
  --- start ---

SNIP

  PERF_RECORD_MMAP for [vdso] missing!
  test child finished with 255
  ---- end ----
  Validate PERF_RECORD_* events & perf_sample fields: FAILED!
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1405353439-14211-1-git-send-email-jolsa@kernel.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

kernel/events/core.c

@@ -5266,6 +5266,12 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
 
 		goto got_name;
 	} else {
+		if (vma->vm_ops && vma->vm_ops->name) {
+			name = (char *) vma->vm_ops->name(vma);
+			if (name)
+				goto cpy_name;
+		}
+
 		name = (char *)arch_vma_name(vma);
 		if (name)
 			goto cpy_name;