On Tue, Dec 11, 2018 at 2:45 PM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > > 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. I'll need to double-check, but it occurs to me that we won't need additional hooks for atomics in KMSAN - the compiler instrumentation should suffice. > Arnd patch does it the other way around: non-instrumented files need > to opt-in instead of opt-out. Shouldn't we put __SANITIZE_ADDRESS__ somewhere into mm/kasan/kasan.h then? > 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 > > -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg
