kasan: Forbid kunit tests when async mode is enabled

Architectures supported by KASAN_HW_TAGS can provide a sync or async
mode of execution. KASAN KUNIT tests can be executed only when sync
mode is enabled.

Forbid the execution of the KASAN KUNIT tests when async mode is
enabled.

Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>

lib/test_kasan.c

@@ -52,6 +52,11 @@ static int kasan_test_init(struct kunit *test)
 		return -1;
 	}
 
+	if (!hw_is_mode_sync()) {
+		kunit_err(test, "can't run KASAN tests in async mode");
+		return -1;
+	}
+
 	multishot = kasan_save_enable_multi_shot();
 	hw_set_tagging_report_once(false);
 	return 0;

mm/kasan/kasan.h

@@ -296,6 +296,7 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 
 #define hw_enable_tagging_sync()		arch_enable_tagging_sync()
 #define hw_enable_tagging_async()		arch_enable_tagging_async()
+#define hw_is_mode_sync()			arch_is_mode_sync()
 #define hw_init_tags(max_tag)			arch_init_tags(max_tag)
 #define hw_set_tagging_report_once(state)	arch_set_tagging_report_once(state)
 #define hw_get_random_tag()			arch_get_random_tag()
@@ -306,6 +307,7 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 
 #define hw_enable_tagging_sync()
 #define hw_enable_tagging_async()
+#define hw_is_mode_sync()
 #define hw_set_tagging_report_once(state)
 
 #endif /* CONFIG_KASAN_HW_TAGS */