[PATCH] perf: Fix display of kernel symbols

Christophe Leroy christophe.leroy at csgroup.eu
Tue Jan 7 06:38:29 AEDT 2025


Since commit 659ad3492b91 ("perf maps: Switch from rbtree to lazily
sorted array for addresses"), perf doesn't display anymore kernel
symbols on powerpc, allthough it still detects them as kernel addresses.

	# Overhead  Command     Shared Object  Symbol
	# ........  ..........  ............. ......................................
	#
	    80.49%  Coeur main  [unknown]      [k] 0xc005f0f8
	     3.91%  Coeur main  gau            [.] engine_loop.constprop.0.isra.0
	     1.72%  Coeur main  [unknown]      [k] 0xc005f11c
	     1.09%  Coeur main  [unknown]      [k] 0xc01f82c8
	     0.44%  Coeur main  libc.so.6      [.] epoll_wait
	     0.38%  Coeur main  [unknown]      [k] 0xc0011718
	     0.36%  Coeur main  [unknown]      [k] 0xc01f45c0

This is because function maps__find_next_entry() now returns current
entry instead of next entry, leading to kernel map end address
getting mis-configured with its own start address instead of the
start address of the following map.

Fix it by really taking the next entry.

Fixes: 659ad3492b91 ("perf maps: Switch from rbtree to lazily sorted array for addresses")
Signed-off-by: Christophe Leroy <christophe.leroy at csgroup.eu>
Reviewed-by: Arnaldo Carvalho de Melo <acme at redhat.com>
---
 tools/perf/util/maps.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index 432399cbe5dd..d39bf27a5fdd 100644
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -1137,7 +1137,7 @@ struct map *maps__find_next_entry(struct maps *maps, struct map *map)
 
 	down_read(maps__lock(maps));
 	i = maps__by_address_index(maps, map);
-	if (i < maps__nr_maps(maps))
+	if (++i < maps__nr_maps(maps))
 		result = map__get(maps__maps_by_address(maps)[i]);
 
 	up_read(maps__lock(maps));
-- 
2.47.0



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