| Message ID | 20230907130642.245222-2-glider@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] kmsan: simplify kmsan_internal_memmove_metadata() | expand |
Hi Alexander, kernel test robot noticed the following build errors: [auto build test ERROR on akpm-mm/mm-everything] [also build test ERROR on linus/master v6.5 next-20230908] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Alexander-Potapenko/kmsan-prevent-optimizations-in-memcpy-tests/20230907-210817 base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything patch link: https://lore.kernel.org/r/20230907130642.245222-2-glider%40google.com patch subject: [PATCH 2/2] kmsan: prevent optimizations in memcpy tests config: x86_64-buildonly-randconfig-006-20230910 (https://download.01.org/0day-ci/archive/20230910/202309100805.cRHktAYd-lkp@intel.com/config) compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230910/202309100805.cRHktAYd-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202309100805.cRHktAYd-lkp@intel.com/ All errors (new ones prefixed by >>): >> mm/kmsan/kmsan_test.c:414:16: error: passing 'volatile void *' to parameter of type 'void *' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers] return memcpy(dst, src, size); ^~~ arch/x86/include/asm/string_64.h:18:27: note: passing argument to parameter 'to' here extern void *memcpy(void *to, const void *from, size_t len); ^ >> mm/kmsan/kmsan_test.c:414:21: error: passing 'const volatile void *' to parameter of type 'const void *' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers] return memcpy(dst, src, size); ^~~ arch/x86/include/asm/string_64.h:18:43: note: passing argument to parameter 'from' here extern void *memcpy(void *to, const void *from, size_t len); ^ >> mm/kmsan/kmsan_test.c:468:21: error: passing 'volatile int *' to parameter of type 'const void *' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers] kmsan_check_memory(&uninit_src, sizeof(uninit_src)); ^~~~~~~~~~~ include/linux/kmsan-checks.h:47:37: note: passing argument to parameter 'address' here void kmsan_check_memory(const void *address, size_t size); ^ 3 errors generated. vim +414 mm/kmsan/kmsan_test.c 409 410 /* Prevent the compiler from inlining a memcpy() call. */ 411 static noinline void *memcpy_noinline(volatile void *dst, 412 const volatile void *src, size_t size) 413 { > 414 return memcpy(dst, src, size); 415 } 416 417 /* Test case: ensure that memcpy() correctly copies initialized values. */ 418 static void test_init_memcpy(struct kunit *test) 419 { 420 EXPECTATION_NO_REPORT(expect); 421 volatile int src; 422 volatile int dst = 0; 423 424 src = 1; 425 kunit_info( 426 test, 427 "memcpy()ing aligned initialized src to aligned dst (no reports)\n"); 428 memcpy_noinline((void *)&dst, (void *)&src, sizeof(src)); 429 kmsan_check_memory((void *)&dst, sizeof(dst)); 430 KUNIT_EXPECT_TRUE(test, report_matches(&expect)); 431 } 432 433 /* 434 * Test case: ensure that memcpy() correctly copies uninitialized values between 435 * aligned `src` and `dst`. 436 */ 437 static void test_memcpy_aligned_to_aligned(struct kunit *test) 438 { 439 EXPECTATION_UNINIT_VALUE_FN(expect, "test_memcpy_aligned_to_aligned"); 440 volatile int uninit_src; 441 volatile int dst = 0; 442 443 kunit_info( 444 test, 445 "memcpy()ing aligned uninit src to aligned dst (UMR report)\n"); 446 memcpy_noinline((void *)&dst, (void *)&uninit_src, sizeof(uninit_src)); 447 kmsan_check_memory((void *)&dst, sizeof(dst)); 448 KUNIT_EXPECT_TRUE(test, report_matches(&expect)); 449 } 450 451 /* 452 * Test case: ensure that memcpy() correctly copies uninitialized values between 453 * aligned `src` and unaligned `dst`. 454 * 455 * Copying aligned 4-byte value to an unaligned one leads to touching two 456 * aligned 4-byte values. This test case checks that KMSAN correctly reports an 457 * error on the first of the two values. 458 */ 459 static void test_memcpy_aligned_to_unaligned(struct kunit *test) 460 { 461 EXPECTATION_UNINIT_VALUE_FN(expect, "test_memcpy_aligned_to_unaligned"); 462 volatile int uninit_src; 463 volatile char dst[8] = { 0 }; 464 465 kunit_info( 466 test, 467 "memcpy()ing aligned uninit src to unaligned dst (UMR report)\n"); > 468 kmsan_check_memory(&uninit_src, sizeof(uninit_src)); 469 memcpy_noinline((void *)&dst[1], (void *)&uninit_src, 470 sizeof(uninit_src)); 471 kmsan_check_memory((void *)dst, 4); 472 KUNIT_EXPECT_TRUE(test, report_matches(&expect)); 473 } 474
diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c index 312989aa2865c..0c32c917b489a 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(dst, 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; - 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(&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)); \
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. Signed-off-by: Alexander Potapenko <glider@google.com> --- mm/kmsan/kmsan_test.c | 37 ++++++++++++++----------------------- 1 file changed, 14 insertions(+), 23 deletions(-)