diff options
Diffstat (limited to 'kernel/kcsan')
| -rw-r--r-- | kernel/kcsan/Makefile | 2 | ||||
| -rw-r--r-- | kernel/kcsan/core.c | 17 |
2 files changed, 14 insertions, 5 deletions
diff --git a/kernel/kcsan/Makefile b/kernel/kcsan/Makefile index 8cf70f068d92..a45f3dfc8d14 100644 --- a/kernel/kcsan/Makefile +++ b/kernel/kcsan/Makefile @@ -16,6 +16,6 @@ obj-y := core.o debugfs.o report.o KCSAN_INSTRUMENT_BARRIERS_selftest.o := y obj-$(CONFIG_KCSAN_SELFTEST) += selftest.o -CFLAGS_kcsan_test.o := $(CFLAGS_KCSAN) -g -fno-omit-frame-pointer +CFLAGS_kcsan_test.o := $(CFLAGS_KCSAN) -fno-omit-frame-pointer CFLAGS_kcsan_test.o += $(DISABLE_STRUCTLEAK_PLUGIN) obj-$(CONFIG_KCSAN_KUNIT_TEST) += kcsan_test.o diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c index 54d077e1a2dc..5a60cc52adc0 100644 --- a/kernel/kcsan/core.c +++ b/kernel/kcsan/core.c @@ -337,11 +337,20 @@ static void delay_access(int type) */ static __always_inline u64 read_instrumented_memory(const volatile void *ptr, size_t size) { + /* + * In the below we don't necessarily need the read of the location to + * be atomic, and we don't use READ_ONCE(), since all we need for race + * detection is to observe 2 different values. + * + * Furthermore, on certain architectures (such as arm64), READ_ONCE() + * may turn into more complex instructions than a plain load that cannot + * do unaligned accesses. + */ switch (size) { - case 1: return READ_ONCE(*(const u8 *)ptr); - case 2: return READ_ONCE(*(const u16 *)ptr); - case 4: return READ_ONCE(*(const u32 *)ptr); - case 8: return READ_ONCE(*(const u64 *)ptr); + case 1: return *(const volatile u8 *)ptr; + case 2: return *(const volatile u16 *)ptr; + case 4: return *(const volatile u32 *)ptr; + case 8: return *(const volatile u64 *)ptr; default: return 0; /* Ignore; we do not diff the values. */ } } |