kmsan: merge test_memcpy_aligned_to_unaligned{,2}() together

Introduce report_reset() that allows checking for more than one KMSAN
report per testcase.

Fold test_memcpy_aligned_to_unaligned2() into
test_memcpy_aligned_to_unaligned(), so that they share the setup phase and
check the behavior of a single memcpy() call.

Link: https://lkml.kernel.org/r/20230911145702.2663753-3-glider@google.comSigned-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kmsan/kmsan_test.c

@@ -67,6 +67,17 @@ static bool report_available(void)
 	return READ_ONCE(observed.available);
 }
 
+/* Reset observed.available, so that the test can trigger another report. */
+static void report_reset(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&observed.lock, flags);
+	WRITE_ONCE(observed.available, false);
+	observed.ignore = false;
+	spin_unlock_irqrestore(&observed.lock, flags);
+}
+
 /* Information we expect in a report. */
 struct expect_report {
 	const char *error_type; /* Error type. */
@@ -454,7 +465,7 @@ static void test_memcpy_aligned_to_aligned(struct kunit *test)
  *
  * Copying aligned 4-byte value to an unaligned one leads to touching two
  * aligned 4-byte values. This test case checks that KMSAN correctly reports an
- * error on the first of the two values.
+ * error on the mentioned two values.
  */
 static void test_memcpy_aligned_to_unaligned(struct kunit *test)
 {
@@ -470,28 +481,7 @@ static void test_memcpy_aligned_to_unaligned(struct kunit *test)
 			sizeof(uninit_src));
 	kmsan_check_memory((void *)dst, 4);
 	KUNIT_EXPECT_TRUE(test, report_matches(&expect));
-}
-
-/*
- * Test case: ensure that memcpy() correctly copies uninitialized values between
- * aligned `src` and unaligned `dst`.
- *
- * Copying aligned 4-byte value to an unaligned one leads to touching two
- * aligned 4-byte values. This test case checks that KMSAN correctly reports an
- * error on the second of the two values.
- */
-static void test_memcpy_aligned_to_unaligned2(struct kunit *test)
-{
-	EXPECTATION_UNINIT_VALUE_FN(expect,
-				    "test_memcpy_aligned_to_unaligned2");
-	volatile int uninit_src;
-	volatile char dst[8] = { 0 };
-
-	kunit_info(
-		test,
-		"memcpy()ing aligned uninit src to unaligned dst - part 2 (UMR report)\n");
-	memcpy_noinline((void *)&dst[1], (void *)&uninit_src,
-			sizeof(uninit_src));
+	report_reset();
 	kmsan_check_memory((void *)&dst[4], sizeof(uninit_src));
 	KUNIT_EXPECT_TRUE(test, report_matches(&expect));
 }
@@ -589,7 +579,6 @@ static struct kunit_case kmsan_test_cases[] = {
 	KUNIT_CASE(test_init_memcpy),
 	KUNIT_CASE(test_memcpy_aligned_to_aligned),
 	KUNIT_CASE(test_memcpy_aligned_to_unaligned),
-	KUNIT_CASE(test_memcpy_aligned_to_unaligned2),
 	KUNIT_CASE(test_memset16),
 	KUNIT_CASE(test_memset32),
 	KUNIT_CASE(test_memset64),