On Thu, Sep 28, 2017 at 4:30 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Thu, Sep 28, 2017 at 6:09 AM, Andrey Ryabinin > <aryabinin@xxxxxxxxxxxxx> wrote: >> On 09/27/2017 04:26 PM, Arnd Bergmann wrote: >>> On Tue, Sep 26, 2017 at 9:49 AM, Andrey Ryabinin >>> <aryabinin@xxxxxxxxxxxxx> wrote: > >>> --- a/include/linux/string.h >>> +++ b/include/linux/string.h >>> @@ -227,7 +227,7 @@ static inline const char *kbasename(const char *path) >>> #define __FORTIFY_INLINE extern __always_inline __attribute__((gnu_inline)) >>> #define __RENAME(x) __asm__(#x) >>> >>> -void fortify_panic(const char *name) __noreturn __cold; >>> +void fortify_panic(const char *name) __cold; >>> void __read_overflow(void) __compiletime_error("detected read beyond >>> size of object passed as 1st parameter"); >>> void __read_overflow2(void) __compiletime_error("detected read beyond >>> size of object passed as 2nd parameter"); >>> void __read_overflow3(void) __compiletime_error("detected read beyond >>> size of object passed as 3rd parameter"); >>> >>> I don't immediately see why the __noreturn changes the behavior here, any idea? >>> >> >> >> At first I thought that this somehow might be related to __asan_handle_no_return(). GCC calls it >> before noreturn function. So I made patch to remove generation of these calls (we don't need them in the kernel anyway) >> but it didn't help. It must be something else than. > > I made a reduced test case yesterday (see http://paste.ubuntu.com/25628030/), > and it shows the same behavior with and without the sanitizer, it uses 128 > bytes without the noreturn attribute and 480 bytes when its added, the sanitizer > adds a factor of 1.5x on top. It's possible that I did something wrong while > reducing, since the original driver file uses very little stack (a few hundred > bytes) without -fsanitize=kernel-address, but finding out what happens in > the reduced case may still help understand the other one. This is now GCC PR82365, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 I've come up with a workaround, but I'm not sure if that is any better than the alternatives, will send the patch as a follow-up in a bit. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html