On Tue, Dec 11, 2018 at 2:35 PM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > Building little-endian allmodconfig kernels on arm64 started failing > with the generated atomic.h implementation, since we now try to call > kasan helpers from the EFI stub: > > aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set': > include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write' > > I suspect that we get similar problems in other files that explicitly > disable KASAN for some reason but call atomic_t based helper functions. > > We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro > that the compiler sets instead of checking CONFIG_KASAN, but this in turn > requires a small hack in mm/kasan/common.c so we do see the extern > declaration there instead of the inline function. Alexander, I think you are doing a similar thing for similar reasons in KMSAN patch (see KMSAN_CHECK_ATOMIC_PARAMS): https://github.com/google/kmsan/commit/17ebbfe19624c84adf79b0e5a74fd258c49ff12b Namely, non-KMSAN-instrumented files must not get KMSAN callbacks from atomics too. Arnd patch does it the other way around: non-instrumented files need to opt-in instead of opt-out. Let's settle on a common way to do this, so that we can use it consistently across all tools. > Fixes: b1864b828644 ("locking/atomics: build atomic headers as required") > Reported-by: Anders Roxell <anders.roxell@xxxxxxxxxx> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > --- > include/linux/kasan-checks.h | 2 +- > mm/kasan/common.c | 2 ++ > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h > index d314150658a4..a61dc075e2ce 100644 > --- a/include/linux/kasan-checks.h > +++ b/include/linux/kasan-checks.h > @@ -2,7 +2,7 @@ > #ifndef _LINUX_KASAN_CHECKS_H > #define _LINUX_KASAN_CHECKS_H > > -#ifdef CONFIG_KASAN > +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL) > void kasan_check_read(const volatile void *p, unsigned int size); > void kasan_check_write(const volatile void *p, unsigned int size); > #else > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 03d5d1374ca7..51a7932c33a3 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -14,6 +14,8 @@ > * > */ > > +#define __KASAN_INTERNAL > + > #include <linux/export.h> > #include <linux/interrupt.h> > #include <linux/init.h> > -- > 2.20.0 >
