[PATCH 06/12] perf tools: Insert split maps correctly into origin group

From: Arnaldo Carvalho de Melo
Date: Thu Nov 05 2015 - 11:03:13 EST

From: Jiri Olsa <jolsa@xxxxxxxxxx>

When new maps are cloned out of split map they are added into origin
map's group, but their groups pointer is not updated.

This could lead to a segfault, because map->groups is expected to be
always set as reported by Markus:

__map__is_kernel (map=map@entry=0x1abb7a0) at util/map.c:238
238 return __machine__kernel_map(map->groups->machine, map->type) =
(gdb) bt
#0 __map__is_kernel (map=map@entry=0x1abb7a0) at util/map.c:238
#1 0x00000000004393e4 in symbol_filter (map=map@entry=0x1abb7a0, sym=sym@entry
#2 0x00000000004fcd4d in dso__load_sym (dso=dso@entry=0x166dae0, map=map@entry
#3 0x00000000004a64e0 in dso__load (dso=0x166dae0, map=map@entry=0x1abb7a0, fi
#4 0x00000000004b941f in map__load (filter=0x4393c0 <symbol_filter>, map=<opti
#5 map__find_symbol (map=0x1abb7a0, addr=40188, filter=0x4393c0 <symbol_filter

Adding __map_groups__insert function to add map into groups together
with map->groups pointer update. It takes no lock as opposed to existing
map_groups__insert, as maps__fixup_overlappings(), where it is being
called, already has the necessary lock held.

Using __map_groups__insert to add new maps after map split.

Reported-by: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Tested-by: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20151104140811.GA32664@xxxxxxxxxxxxxxxxxxxx
Fixes: cfc5acd4c80b ("perf top: Filter symbols based on __map__is_kernel(map)")
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
tools/perf/util/map.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 4e38c396a897..afc6b56cf749 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -644,6 +644,12 @@ size_t map_groups__fprintf(struct map_groups *mg, FILE *fp)
return printed;

+static void __map_groups__insert(struct map_groups *mg, struct map *map)
+ __maps__insert(&mg->maps[map->type], map);
+ map->groups = mg;
static int maps__fixup_overlappings(struct maps *maps, struct map *map, FILE *fp)
struct rb_root *root;
@@ -682,7 +688,7 @@ static int maps__fixup_overlappings(struct maps *maps, struct map *map, FILE *fp

before->end = map->start;
- __maps__insert(maps, before);
+ __map_groups__insert(pos->groups, before);
if (verbose >= 2)
map__fprintf(before, fp);
@@ -696,7 +702,7 @@ static int maps__fixup_overlappings(struct maps *maps, struct map *map, FILE *fp

after->start = map->end;
- __maps__insert(maps, after);
+ __map_groups__insert(pos->groups, after);
if (verbose >= 2)
map__fprintf(after, fp);

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