kselftest/arm64: mte: user_mem: rework error handling

Future commits will have multiple iterations of tests in this function,
so make the error handling assume it will pass and then bail out if there
is an error.
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220209152240.52788-3-joey.gouly@arm.comSigned-off-by: Will Deacon <will@kernel.org>

tools/testing/selftests/arm64/mte/check_user_mem.c

@@ -27,7 +27,7 @@ static int check_usermem_access_fault(int mem_type, int mode, int mapping,
 	size_t len, read_len;
 	void *ptr, *ptr_next;
 
-	err = KSFT_FAIL;
+	err = KSFT_PASS;
 	len = 2 * page_sz;
 	mte_switch_mode(mode, MTE_ALLOW_NON_ZERO_TAG);
 	fd = create_temp_file();
@@ -71,14 +71,22 @@ static int check_usermem_access_fault(int mem_type, int mode, int mapping,
 	 * mode without fault but may not fail in async mode as per the
 	 * implemented MTE userspace support in Arm64 kernel.
 	 */
-	if (mode == MTE_SYNC_ERR &&
-	    !cur_mte_cxt.fault_valid && read_len < len) {
-		err = KSFT_PASS;
-	} else if (mode == MTE_ASYNC_ERR &&
-		   !cur_mte_cxt.fault_valid && read_len == len) {
-		err = KSFT_PASS;
+	if (cur_mte_cxt.fault_valid)
+		goto usermem_acc_err;
+
+	if (mode == MTE_SYNC_ERR && read_len < len) {
+		/* test passed */
+	} else if (mode == MTE_ASYNC_ERR && read_len == len) {
+		/* test passed */
+	} else {
+		goto usermem_acc_err;
 	}
+
+	goto exit;
+
 usermem_acc_err:
+	err = KSFT_FAIL;
+exit:
 	mte_free_memory((void *)ptr, len, mem_type, true);
 	close(fd);
 	return err;