From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Tue, 18 Apr 2023 20:33:48 +0000 (-0300)
Subject: perf maps: Add maps__refcnt() accessor to allow checking maps pointer
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=fe693d951e3c303b4fb6c712f8affecbe9e8b001;p=linux.git

perf maps: Add maps__refcnt() accessor to allow checking maps pointer

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

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

diff --git a/tools/perf/tests/thread-maps-share.c b/tools/perf/tests/thread-maps-share.c
index 84edd82c519e2..caf8fbe7c4409 100644
--- a/tools/perf/tests/thread-maps-share.c
+++ b/tools/perf/tests/thread-maps-share.c
@@ -43,7 +43,7 @@ static int test__thread_maps_share(struct test_suite *test __maybe_unused, int s
 			leader && t1 && t2 && t3 && other);
 
 	maps = leader->maps;
-	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(&maps->refcnt), 4);
+	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(maps)), 4);
 
 	/* test the maps pointer is shared */
 	TEST_ASSERT_VAL("maps don't match", maps == t1->maps);
@@ -71,25 +71,25 @@ static int test__thread_maps_share(struct test_suite *test __maybe_unused, int s
 	machine__remove_thread(machine, other_leader);
 
 	other_maps = other->maps;
-	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(&other_maps->refcnt), 2);
+	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(other_maps)), 2);
 
 	TEST_ASSERT_VAL("maps don't match", other_maps == other_leader->maps);
 
 	/* release thread group */
 	thread__put(leader);
-	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(&maps->refcnt), 3);
+	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(maps)), 3);
 
 	thread__put(t1);
-	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(&maps->refcnt), 2);
+	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(maps)), 2);
 
 	thread__put(t2);
-	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(&maps->refcnt), 1);
+	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(maps)), 1);
 
 	thread__put(t3);
 
 	/* release other group  */
 	thread__put(other_leader);
-	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(&other_maps->refcnt), 1);
+	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(other_maps)), 1);
 
 	thread__put(other);
 
diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index 5afed53ea0b4a..953dc20d55d7d 100644
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -12,13 +12,13 @@
 
 static void maps__init(struct maps *maps, struct machine *machine)
 {
+	refcount_set(maps__refcnt(maps), 1);
 	maps->entries = RB_ROOT;
 	init_rwsem(maps__lock(maps));
 	maps->machine = machine;
 	maps->last_search_by_name = NULL;
 	maps->nr_maps = 0;
 	maps->maps_by_name = NULL;
-	refcount_set(&maps->refcnt, 1);
 }
 
 static void __maps__free_maps_by_name(struct maps *maps)
@@ -180,14 +180,14 @@ void maps__delete(struct maps *maps)
 struct maps *maps__get(struct maps *maps)
 {
 	if (maps)
-		refcount_inc(&maps->refcnt);
+		refcount_inc(maps__refcnt(maps));
 
 	return maps;
 }
 
 void maps__put(struct maps *maps)
 {
-	if (maps && refcount_dec_and_test(&maps->refcnt))
+	if (maps && refcount_dec_and_test(maps__refcnt(maps)))
 		maps__delete(maps);
 }
 
diff --git a/tools/perf/util/maps.h b/tools/perf/util/maps.h
index bde3390c7096d..cfb1b79d16713 100644
--- a/tools/perf/util/maps.h
+++ b/tools/perf/util/maps.h
@@ -88,6 +88,11 @@ static inline unsigned int maps__nr_maps(const struct maps *maps)
 	return maps->nr_maps;
 }
 
+static inline refcount_t *maps__refcnt(struct maps *maps)
+{
+	return &maps->refcnt;
+}
+
 #ifdef HAVE_LIBUNWIND_SUPPORT
 static inline void *maps__addr_space(struct maps *maps)
 {