libperf rc_check: Add RC_CHK_EQUAL

Comparing pointers with reference count checking is tricky to avoid a
SEGV. Add a convenience macro to simplify and use.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: James Clark <james.clark@arm.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: liuwenyu <liuwenyu7@huawei.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20231024222353.3024098-5-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Author: captain5050

tools/lib/perf/include/internal/rc_check.h

@@ -54,6 +54,9 @@
 /* A put operation removing the indirection layer. */
 #define RC_CHK_PUT(object) {}
 
+/* Pointer equality when the indirection may or may not be there. */
+#define RC_CHK_EQUAL(object1, object2) (object1 == object2)
+
 #else
 
 /* Replaces "struct foo" so that the pointer may be interposed. */
@@ -101,6 +104,10 @@
 		}				\
 	} while(0)
 
+/* Pointer equality when the indirection may or may not be there. */
+#define RC_CHK_EQUAL(object1, object2) (object1 == object2 || \
+		(object1 && object2 && object1->orig == object2->orig))
+
 #endif
 
 #endif /* __LIBPERF_INTERNAL_RC_CHECK_H */

tools/perf/builtin-sched.c

@@ -1385,7 +1385,7 @@ static int pid_cmp(struct work_atoms *l, struct work_atoms *r)
 {
 	pid_t l_tid, r_tid;
 
-	if (RC_CHK_ACCESS(l->thread) == RC_CHK_ACCESS(r->thread))
+	if (RC_CHK_EQUAL(l->thread, r->thread))
 		return 0;
 	l_tid = thread__tid(l->thread);
 	r_tid = thread__tid(r->thread);

tools/perf/tests/hists_link.c

@@ -148,8 +148,8 @@ static int find_sample(struct sample *samples, size_t nr_samples,
 		       struct thread *t, struct map *m, struct symbol *s)
 {
 	while (nr_samples--) {
-		if (RC_CHK_ACCESS(samples->thread) == RC_CHK_ACCESS(t) &&
-		    RC_CHK_ACCESS(samples->map) == RC_CHK_ACCESS(m) &&
+		if (RC_CHK_EQUAL(samples->thread, t) &&
+		    RC_CHK_EQUAL(samples->map, m) &&
 		    samples->sym == s)
 			return 1;
 		samples++;

tools/perf/tests/thread-maps-share.c

@@ -46,9 +46,9 @@ static int test__thread_maps_share(struct test_suite *test __maybe_unused, int s
 	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(maps)), 4);
 
 	/* test the maps pointer is shared */
-	TEST_ASSERT_VAL("maps don't match", RC_CHK_ACCESS(maps) == RC_CHK_ACCESS(thread__maps(t1)));
-	TEST_ASSERT_VAL("maps don't match", RC_CHK_ACCESS(maps) == RC_CHK_ACCESS(thread__maps(t2)));
-	TEST_ASSERT_VAL("maps don't match", RC_CHK_ACCESS(maps) == RC_CHK_ACCESS(thread__maps(t3)));
+	TEST_ASSERT_VAL("maps don't match", RC_CHK_EQUAL(maps, thread__maps(t1)));
+	TEST_ASSERT_VAL("maps don't match", RC_CHK_EQUAL(maps, thread__maps(t2)));
+	TEST_ASSERT_VAL("maps don't match", RC_CHK_EQUAL(maps, thread__maps(t3)));
 
 	/*
 	 * Verify the other leader was created by previous call.
@@ -73,8 +73,7 @@ static int test__thread_maps_share(struct test_suite *test __maybe_unused, int s
 	other_maps = thread__maps(other);
 	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(other_maps)), 2);
 
-	TEST_ASSERT_VAL("maps don't match", RC_CHK_ACCESS(other_maps) ==
-					    RC_CHK_ACCESS(thread__maps(other_leader)));
+	TEST_ASSERT_VAL("maps don't match", RC_CHK_EQUAL(other_maps, thread__maps(other_leader)));
 
 	/* release thread group */
 	thread__put(t3);

tools/perf/util/callchain.c

@@ -1142,7 +1142,7 @@ int fill_callchain_info(struct addr_location *al, struct callchain_cursor_node *
 		if (al->map == NULL)
 			goto out;
 	}
-	if (RC_CHK_ACCESS(al->maps) == RC_CHK_ACCESS(machine__kernel_maps(machine))) {
+	if (RC_CHK_EQUAL(al->maps, machine__kernel_maps(machine))) {
 		if (machine__is_host(machine)) {
 			al->cpumode = PERF_RECORD_MISC_KERNEL;
 			al->level = 'k';

tools/perf/util/hist.c

@@ -2142,7 +2142,7 @@ static bool hists__filter_entry_by_thread(struct hists *hists,
 					  struct hist_entry *he)
 {
 	if (hists->thread_filter != NULL &&
-	    RC_CHK_ACCESS(he->thread) != RC_CHK_ACCESS(hists->thread_filter)) {
+	    !RC_CHK_EQUAL(he->thread, hists->thread_filter)) {
 		he->filtered |= (1 << HIST_FILTER__THREAD);
 		return true;
 	}

tools/perf/util/machine.c

@@ -969,7 +969,7 @@ static int machine__process_ksymbol_unregister(struct machine *machine,
 	if (!map)
 		return 0;
 
-	if (RC_CHK_ACCESS(map) != RC_CHK_ACCESS(machine->vmlinux_map))
+	if (!RC_CHK_EQUAL(map, machine->vmlinux_map))
 		maps__remove(machine__kernel_maps(machine), map);
 	else {
 		struct dso *dso = map__dso(map);
@@ -2058,7 +2058,7 @@ static void __machine__remove_thread(struct machine *machine, struct thread_rb_n
 	if (!nd)
 		nd = thread_rb_node__find(th, &threads->entries.rb_root);
 
-	if (threads->last_match && RC_CHK_ACCESS(threads->last_match) == RC_CHK_ACCESS(th))
+	if (threads->last_match && RC_CHK_EQUAL(threads->last_match, th))
 		threads__set_last_match(threads, NULL);
 
 	if (lock)

tools/perf/util/sort.c

@@ -128,7 +128,7 @@ static int hist_entry__thread_filter(struct hist_entry *he, int type, const void
 	if (type != HIST_FILTER__THREAD)
 		return -1;
 
-	return th && RC_CHK_ACCESS(he->thread) != RC_CHK_ACCESS(th);
+	return th && !RC_CHK_EQUAL(he->thread, th);
 }
 
 struct sort_entry sort_thread = {

tools/perf/util/symbol.c

@@ -877,7 +877,7 @@ static int maps__split_kallsyms(struct maps *kmaps, struct dso *dso, u64 delta,
 			*module++ = '\0';
 			curr_map_dso = map__dso(curr_map);
 			if (strcmp(curr_map_dso->short_name, module)) {
-				if (RC_CHK_ACCESS(curr_map) != RC_CHK_ACCESS(initial_map) &&
+				if (!RC_CHK_EQUAL(curr_map, initial_map) &&
 				    dso->kernel == DSO_SPACE__KERNEL_GUEST &&
 				    machine__is_default_guest(machine)) {
 					/*
@@ -1469,7 +1469,7 @@ static int dso__load_kcore(struct dso *dso, struct map *map,
 
 		list_del_init(&new_node->node);
 
-		if (RC_CHK_ACCESS(new_map) == RC_CHK_ACCESS(replacement_map)) {
+		if (RC_CHK_EQUAL(new_map, replacement_map)) {
 			struct map *map_ref;
 
 			map__set_start(map, map__start(new_map));