[PATCH v1 4/7] perf maps: Check map__start_cmp() in __maps__insert()

[Ian Rogers]

In __maps__insert(), maps_by_address_sorted is kept true if the previous
map's end is less than or equal to the new map's start. However, when a
map has an end of 0 (for example, an unmapped [0, 0) map or a map whose
end has not been set yet) and a [0, 0) map is inserted after it,
map__end(prev) <= map__start(new) evaluates to 0 <= 0 (true) even when
map__start_cmp(&prev, &new) > 0 (either because map__start(prev) > 0 or
because prev's pointer address is greater than new's pointer address).
This leaves maps_by_address_sorted set to true on an array that is not
ordered according to map__start_cmp(), causing bsearch() in
maps__by_address_index() to fail and return -1 during __maps__remove().

Also check map__start_cmp(&maps_by_address[nr_maps - 2], &new) <= 0 when
updating maps_by_address_sorted in __maps__insert().

Fixes: 659ad3492b91 ("perf maps: Switch from rbtree to lazily sorted array for addresses")
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/perf/util/maps.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index f808df2fe77b..675fe0223faa 100644
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -519,7 +519,8 @@ static int __maps__insert(struct maps *maps, struct map *new)
 		/* Sorted if maps were already sorted and this map starts after the last one. */
 		maps__set_maps_by_address_sorted(maps,
 			maps__maps_by_address_sorted(maps) &&
-			map__end(maps_by_address[nr_maps - 2]) <= map__start(new));
+			map__end(maps_by_address[nr_maps - 2]) <= map__start(new) &&
+			map__start_cmp(&maps_by_address[nr_maps - 2], &new) <= 0);
 		maps__set_maps_by_name_sorted(maps, false);
 	}
 	if (map__end(new) < map__start(new))
-- 
2.56.0.307.g5fe7bd680c-goog