On 03/02/2017 07:38 PM, Arnd Bergmann wrote: > When CONFIG_KASAN is set, we can run into some code that uses incredible > amounts of kernel stack: > > drivers/staging/dgnc/dgnc_neo.c:1056:1: error: the frame size of 11112 bytes is larger than 2048 bytes [-Werror=frame-larger-than=] > drivers/media/i2c/cx25840/cx25840-core.c:4960:1: error: the frame size of 94000 bytes is larger than 2048 bytes [-Werror=frame-larger-than=] > drivers/media/dvb-frontends/stv090x.c:3430:1: error: the frame size of 5312 bytes is larger than 3072 bytes [-Werror=frame-larger-than=] > > This happens when a sanitizer uses stack memory each time an inline function > gets called. This introduces a new annotation for those functions to make > them either 'inline' or 'noinline' dependning on the CONFIG_KASAN symbol. > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > --- > include/linux/compiler.h | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > index f8110051188f..56b90897a459 100644 > --- a/include/linux/compiler.h > +++ b/include/linux/compiler.h > @@ -416,6 +416,17 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s > */ > #define noinline_for_stack noinline > > +/* > + * CONFIG_KASAN can lead to extreme stack usage with certain patterns when > + * one function gets inlined many times and each instance requires a stack > + * ckeck. > + */ > +#ifdef CONFIG_KASAN > +#define noinline_for_kasan noinline __maybe_unused noinline_iff_kasan might be a better name. noinline_for_kasan gives the impression that we always noinline function for the sake of kasan, while noinline_iff_kasan clearly indicates that function is noinline only if kasan is used. > +#else > +#define noinline_for_kasan inline > +#endif > + > #ifndef __always_inline > #define __always_inline inline > #endif >
