perf map: Add map__refcnt() accessor to use in the maps test

To remove one more direct access to 'struct map' so that we can intecept
accesses to its instantiations and refcount check it to catch use after
free, etc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Link: https://lore.kernel.org/lkml/ZDbRIJknafLnDwtO@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/maps.c

@@ -30,7 +30,7 @@ static int check_maps(struct map_def *merged, unsigned int size, struct maps *ma
 			if (map__start(map) != merged[i].start ||
 			    map__end(map) != merged[i].end ||
 			    strcmp(map__dso(map)->name, merged[i].name) ||
-			    refcount_read(&map->refcnt) != 1) {
+			    refcount_read(map__refcnt(map)) != 1) {
 				failed = true;
 			}
 			i++;
@@ -50,7 +50,7 @@ static int check_maps(struct map_def *merged, unsigned int size, struct maps *ma
 				map__start(map),
 				map__end(map),
 				map__dso(map)->name,
-				refcount_read(&map->refcnt));
+				refcount_read(map__refcnt(map)));
 		}
 	}
 	return failed ? TEST_FAIL : TEST_OK;

tools/perf/util/map.h

@@ -97,6 +97,11 @@ static inline bool map__priv(const struct map *map)
 	return map->priv;
 }
 
+static inline refcount_t *map__refcnt(struct map *map)
+{
+	return &map->refcnt;
+}
+
 static inline size_t map__size(const struct map *map)
 {
 	return map__end(map) - map__start(map);