perf kmaps: Check kmaps to make code more robust

This patch add checks in places where map__kmap is used to get kmaps
from struct kmap.

Error messages are added at map__kmap to warn invalid accessing of kmap
(for the case of !map->dso->kernel, kmap(map) does not exists at all).

Also, introduces map__kmaps() to warn uninitialized kmaps.

Reviewed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: pi3orama@163.com
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1428394966-131044-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 62ca9f2607d5..a14f08f41686 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -778,3 +778,23 @@ struct map *maps__next(struct map *map)
 		return rb_entry(next, struct map, rb_node);
 	return NULL;
 }
+
+struct kmap *map__kmap(struct map *map)
+{
+	if (!map->dso || !map->dso->kernel) {
+		pr_err("Internal error: map__kmap with a non-kernel map\n");
+		return NULL;
+	}
+	return (struct kmap *)(map + 1);
+}
+
+struct map_groups *map__kmaps(struct map *map)
+{
+	struct kmap *kmap = map__kmap(map);
+
+	if (!kmap || !kmap->kmaps) {
+		pr_err("Internal error: map__kmaps with a non-kernel map\n");
+		return NULL;
+	}
+	return kmap->kmaps;
+}