diff options
author | Alexander Potapenko <glider@google.com> | 2023-09-11 16:57:00 +0200 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2023-10-04 10:32:22 -0700 |
commit | 0be7b2c232cfb1621660c78b0fd7260361c75e27 (patch) | |
tree | 22ab2cba4a295674bab7b06b1b2b0782a82dfa3d /mm/kmsan | |
parent | be1ab60eb04f27e559d8be9655beb04d2bc90b25 (diff) |
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>
Diffstat (limited to 'mm/kmsan')
-rw-r--r-- | mm/kmsan/kmsan_test.c | 41 |
1 files changed, 16 insertions, 25 deletions
diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c index 312989aa2865..a8d4ca4a1066 100644 --- a/mm/kmsan/kmsan_test.c +++ b/mm/kmsan/kmsan_test.c @@ -407,33 +407,25 @@ static void test_printk(struct kunit *test) KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } -/* - * Prevent the compiler from optimizing @var away. Without this, Clang may - * notice that @var is uninitialized and drop memcpy() calls that use it. - * - * There is OPTIMIZER_HIDE_VAR() in linux/compier.h that we cannot use here, - * because it is implemented as inline assembly receiving @var as a parameter - * and will enforce a KMSAN check. Same is true for e.g. barrier_data(var). - */ -#define DO_NOT_OPTIMIZE(var) barrier() +/* Prevent the compiler from inlining a memcpy() call. */ +static noinline void *memcpy_noinline(volatile void *dst, + const volatile void *src, size_t size) +{ + return memcpy((void *)dst, (const void *)src, size); +} -/* - * Test case: ensure that memcpy() correctly copies initialized values. - * Also serves as a regression test to ensure DO_NOT_OPTIMIZE() does not cause - * extra checks. - */ +/* Test case: ensure that memcpy() correctly copies initialized values. */ static void test_init_memcpy(struct kunit *test) { EXPECTATION_NO_REPORT(expect); - volatile int src; - volatile int dst = 0; + volatile long long src; + volatile long long dst = 0; - DO_NOT_OPTIMIZE(src); src = 1; kunit_info( test, "memcpy()ing aligned initialized src to aligned dst (no reports)\n"); - memcpy((void *)&dst, (void *)&src, sizeof(src)); + memcpy_noinline((void *)&dst, (void *)&src, sizeof(src)); kmsan_check_memory((void *)&dst, sizeof(dst)); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } @@ -451,8 +443,7 @@ static void test_memcpy_aligned_to_aligned(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to aligned dst (UMR report)\n"); - DO_NOT_OPTIMIZE(uninit_src); - memcpy((void *)&dst, (void *)&uninit_src, sizeof(uninit_src)); + memcpy_noinline((void *)&dst, (void *)&uninit_src, sizeof(uninit_src)); kmsan_check_memory((void *)&dst, sizeof(dst)); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } @@ -474,8 +465,9 @@ static void test_memcpy_aligned_to_unaligned(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to unaligned dst (UMR report)\n"); - DO_NOT_OPTIMIZE(uninit_src); - memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src)); + kmsan_check_memory((void *)&uninit_src, sizeof(uninit_src)); + memcpy_noinline((void *)&dst[1], (void *)&uninit_src, + sizeof(uninit_src)); kmsan_check_memory((void *)dst, 4); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } @@ -498,8 +490,8 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to unaligned dst - part 2 (UMR report)\n"); - DO_NOT_OPTIMIZE(uninit_src); - memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src)); + memcpy_noinline((void *)&dst[1], (void *)&uninit_src, + sizeof(uninit_src)); kmsan_check_memory((void *)&dst[4], sizeof(uninit_src)); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } @@ -513,7 +505,6 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test) \ kunit_info(test, \ "memset" #size "() should initialize memory\n"); \ - DO_NOT_OPTIMIZE(uninit); \ memset##size((uint##size##_t *)&uninit, 0, 1); \ kmsan_check_memory((void *)&uninit, sizeof(uninit)); \ KUNIT_EXPECT_TRUE(test, report_matches(&expect)); \ |