perf tools: Add __data_loc support

This patch is required to test the next patch for perf lock.

At 064739bc4b3d7f424b2f25547e6611bcf0132415 ,
support for the modifier "__data_loc" of format is added.

But, when I wanted to parse format of lock_acquired (or some
event else), raw_field_ptr() did not returned correct pointer.

So I modified raw_field_ptr() like this patch. Then
raw_field_ptr() works well.

Signed-off-by: Hitoshi Mitake <[e-mail]>
Acked-by: Frederic Weisbecker <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Tom Zanussi <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
LKML-Reference: <[e-mail]>
[ v3: fixed minor stylistic detail ]
Signed-off-by: Ingo Molnar <[e-mail]>

tools/perf/util/trace-event-parse.c

···
 	if (!field)
 		return NULL;
 
+	if (field->flags & FIELD_IS_STRING) {
+		int offset;
+
+		offset = *(int *)(data + field->offset);
+		offset &= 0xffff;
+
+		return data + offset;
+	}
+
 	return data + field->offset;
 }