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kmsan: prevent optimizations in memcpy tests
Clang 18 learned to optimize away memcpy() calls of small uninitialized scalar values. To ensure that memcpy tests in kmsan_test.c still perform calls to memcpy() (which KMSAN replaces with __msan_memcpy()), declare a separate memcpy_noinline() function with volatile parameters, which won't be optimized. Also retire DO_NOT_OPTIMIZE(), as memcpy_noinline() is apparently enough. Link: https://lkml.kernel.org/r/20230911145702.2663753-2-glider@google.com Signed-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>
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@ -407,33 +407,25 @@ static void test_printk(struct kunit *test)
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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}
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}
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/*
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/* Prevent the compiler from inlining a memcpy() call. */
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* Prevent the compiler from optimizing @var away. Without this, Clang may
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static noinline void *memcpy_noinline(volatile void *dst,
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* notice that @var is uninitialized and drop memcpy() calls that use it.
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const volatile void *src, size_t size)
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*
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{
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* There is OPTIMIZER_HIDE_VAR() in linux/compier.h that we cannot use here,
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return memcpy((void *)dst, (const void *)src, size);
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* because it is implemented as inline assembly receiving @var as a parameter
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}
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* and will enforce a KMSAN check. Same is true for e.g. barrier_data(var).
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*/
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#define DO_NOT_OPTIMIZE(var) barrier()
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/*
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/* Test case: ensure that memcpy() correctly copies initialized values. */
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* Test case: ensure that memcpy() correctly copies initialized values.
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* Also serves as a regression test to ensure DO_NOT_OPTIMIZE() does not cause
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* extra checks.
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*/
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static void test_init_memcpy(struct kunit *test)
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static void test_init_memcpy(struct kunit *test)
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{
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{
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EXPECTATION_NO_REPORT(expect);
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EXPECTATION_NO_REPORT(expect);
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volatile int src;
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volatile long long src;
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volatile int dst = 0;
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volatile long long dst = 0;
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DO_NOT_OPTIMIZE(src);
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src = 1;
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src = 1;
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kunit_info(
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kunit_info(
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test,
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test,
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"memcpy()ing aligned initialized src to aligned dst (no reports)\n");
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"memcpy()ing aligned initialized src to aligned dst (no reports)\n");
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memcpy((void *)&dst, (void *)&src, sizeof(src));
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memcpy_noinline((void *)&dst, (void *)&src, sizeof(src));
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kmsan_check_memory((void *)&dst, sizeof(dst));
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kmsan_check_memory((void *)&dst, sizeof(dst));
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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}
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}
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@ -451,8 +443,7 @@ static void test_memcpy_aligned_to_aligned(struct kunit *test)
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kunit_info(
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kunit_info(
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test,
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test,
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"memcpy()ing aligned uninit src to aligned dst (UMR report)\n");
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"memcpy()ing aligned uninit src to aligned dst (UMR report)\n");
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DO_NOT_OPTIMIZE(uninit_src);
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memcpy_noinline((void *)&dst, (void *)&uninit_src, sizeof(uninit_src));
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memcpy((void *)&dst, (void *)&uninit_src, sizeof(uninit_src));
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kmsan_check_memory((void *)&dst, sizeof(dst));
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kmsan_check_memory((void *)&dst, sizeof(dst));
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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}
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}
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@ -474,8 +465,9 @@ static void test_memcpy_aligned_to_unaligned(struct kunit *test)
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kunit_info(
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kunit_info(
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test,
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test,
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"memcpy()ing aligned uninit src to unaligned dst (UMR report)\n");
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"memcpy()ing aligned uninit src to unaligned dst (UMR report)\n");
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DO_NOT_OPTIMIZE(uninit_src);
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kmsan_check_memory((void *)&uninit_src, sizeof(uninit_src));
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memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src));
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memcpy_noinline((void *)&dst[1], (void *)&uninit_src,
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sizeof(uninit_src));
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kmsan_check_memory((void *)dst, 4);
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kmsan_check_memory((void *)dst, 4);
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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}
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}
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@ -498,8 +490,8 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test)
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kunit_info(
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kunit_info(
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test,
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test,
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"memcpy()ing aligned uninit src to unaligned dst - part 2 (UMR report)\n");
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"memcpy()ing aligned uninit src to unaligned dst - part 2 (UMR report)\n");
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DO_NOT_OPTIMIZE(uninit_src);
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memcpy_noinline((void *)&dst[1], (void *)&uninit_src,
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memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src));
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sizeof(uninit_src));
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kmsan_check_memory((void *)&dst[4], sizeof(uninit_src));
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kmsan_check_memory((void *)&dst[4], sizeof(uninit_src));
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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KUNIT_EXPECT_TRUE(test, report_matches(&expect));
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}
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}
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@ -513,7 +505,6 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test)
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\
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\
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kunit_info(test, \
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kunit_info(test, \
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"memset" #size "() should initialize memory\n"); \
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"memset" #size "() should initialize memory\n"); \
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DO_NOT_OPTIMIZE(uninit); \
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memset##size((uint##size##_t *)&uninit, 0, 1); \
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memset##size((uint##size##_t *)&uninit, 0, 1); \
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kmsan_check_memory((void *)&uninit, sizeof(uninit)); \
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kmsan_check_memory((void *)&uninit, sizeof(uninit)); \
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KUNIT_EXPECT_TRUE(test, report_matches(&expect)); \
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KUNIT_EXPECT_TRUE(test, report_matches(&expect)); \
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