kasan: test: support async (again) and asymm modes for HW_TAGS

Async mode support has already been implemented in commit e80a76aa1a91
("kasan, arm64: tests supports for HW_TAGS async mode") but then got
accidentally broken in commit 99734b535d9b ("kasan: detect false-positives
in tests").

Restore the changes removed by the latter patch and adapt them for asymm
mode: add a sync_fault flag to kunit_kasan_expectation that only get set
if the MTE fault was synchronous, and reenable MTE on such faults in
tests.

Also rename kunit_kasan_expectation to kunit_kasan_status and move its
definition to mm/kasan/kasan.h from include/linux/kasan.h, as this
structure is only internally used by KASAN.  Also put the structure
definition under IS_ENABLED(CONFIG_KUNIT).

Link: https://lkml.kernel.org/r/133970562ccacc93ba19d754012c562351d4a8c8.1645033139.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 17 deletions

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 2addd0c66acf..72391f992689 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -37,7 +37,7 @@ void *kasan_ptr_result;
 int kasan_int_result;
 
 static struct kunit_resource resource;
-static struct kunit_kasan_expectation fail_data;
+static struct kunit_kasan_status test_status;
 static bool multishot;
 
 /*
@@ -54,58 +54,63 @@ static int kasan_test_init(struct kunit *test)
 	}
 
 	multishot = kasan_save_enable_multi_shot();
-	fail_data.report_found = false;
+	test_status.report_found = false;
+	test_status.sync_fault = false;
 	kunit_add_named_resource(test, NULL, NULL, &resource,
-					"kasan_data", &fail_data);
+					"kasan_status", &test_status);
 	return 0;
 }
 
 static void kasan_test_exit(struct kunit *test)
 {
 	kasan_restore_multi_shot(multishot);
-	KUNIT_EXPECT_FALSE(test, fail_data.report_found);
+	KUNIT_EXPECT_FALSE(test, test_status.report_found);
 }
 
 /**
  * KUNIT_EXPECT_KASAN_FAIL() - check that the executed expression produces a
  * KASAN report; causes a test failure otherwise. This relies on a KUnit
- * resource named "kasan_data". Do not use this name for KUnit resources
+ * resource named "kasan_status". Do not use this name for KUnit resources
  * outside of KASAN tests.
  *
- * For hardware tag-based KASAN in sync mode, when a tag fault happens, tag
+ * For hardware tag-based KASAN, when a synchronous tag fault happens, tag
  * checking is auto-disabled. When this happens, this test handler reenables
  * tag checking. As tag checking can be only disabled or enabled per CPU,
  * this handler disables migration (preemption).
  *
- * Since the compiler doesn't see that the expression can change the fail_data
+ * Since the compiler doesn't see that the expression can change the test_status
  * fields, it can reorder or optimize away the accesses to those fields.
  * Use READ/WRITE_ONCE() for the accesses and compiler barriers around the
  * expression to prevent that.
  *
- * In between KUNIT_EXPECT_KASAN_FAIL checks, fail_data.report_found is kept as
- * false. This allows detecting KASAN reports that happen outside of the checks
- * by asserting !fail_data.report_found at the start of KUNIT_EXPECT_KASAN_FAIL
- * and in kasan_test_exit.
+ * In between KUNIT_EXPECT_KASAN_FAIL checks, test_status.report_found is kept
+ * as false. This allows detecting KASAN reports that happen outside of the
+ * checks by asserting !test_status.report_found at the start of
+ * KUNIT_EXPECT_KASAN_FAIL and in kasan_test_exit.
  */
 #define KUNIT_EXPECT_KASAN_FAIL(test, expression) do {			\
 	if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) &&				\
 	    kasan_sync_fault_possible())				\
 		migrate_disable();					\
-	KUNIT_EXPECT_FALSE(test, READ_ONCE(fail_data.report_found));	\
+	KUNIT_EXPECT_FALSE(test, READ_ONCE(test_status.report_found));	\
 	barrier();							\
 	expression;							\
 	barrier();							\
-	if (!READ_ONCE(fail_data.report_found)) {			\
+	if (kasan_async_fault_possible())				\
+		kasan_force_async_fault();				\
+	if (!READ_ONCE(test_status.report_found)) {			\
 		KUNIT_FAIL(test, KUNIT_SUBTEST_INDENT "KASAN failure "	\
 				"expected in \"" #expression		\
 				 "\", but none occurred");		\
 	}								\
-	if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) {				\
-		if (READ_ONCE(fail_data.report_found))			\
-			kasan_enable_tagging_sync();			\
+	if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) &&				\
+	    kasan_sync_fault_possible()) {				\
+		if (READ_ONCE(test_status.report_found) &&		\
+		    READ_ONCE(test_status.sync_fault))			\
+			kasan_enable_tagging();				\
 		migrate_enable();					\
 	}								\
-	WRITE_ONCE(fail_data.report_found, false);			\
+	WRITE_ONCE(test_status.report_found, false);			\
 } while (0)
 
 #define KASAN_TEST_NEEDS_CONFIG_ON(test, config) do {			\