On Thu, Sep 23, 2021 at 12:07:17PM +0200, Marco Elver wrote: > On Wed, 22 Sept 2021 at 22:55, Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > Currently, the asan-stack parameter is only passed along if > > CFLAGS_KASAN_SHADOW is not empty, which requires KASAN_SHADOW_OFFSET to > > be defined in Kconfig so that the value can be checked. In RISC-V's > > case, KASAN_SHADOW_OFFSET is not defined in Kconfig, which means that > > asan-stack does not get disabled with clang even when CONFIG_KASAN_STACK > > is disabled, resulting in large stack warnings with allmodconfig: > > > > drivers/video/fbdev/omap2/omapfb/displays/panel-lgphilips-lb035q02.c:117:12: > > error: stack frame size (14400) exceeds limit (2048) in function > > 'lb035q02_connect' [-Werror,-Wframe-larger-than] > > static int lb035q02_connect(struct omap_dss_device *dssdev) > > ^ > > 1 error generated. > > > > Ensure that the value of CONFIG_KASAN_STACK is always passed along to > > the compiler so that these warnings do not happen when > > CONFIG_KASAN_STACK is disabled. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1453 > > References: 6baec880d7a5 ("kasan: turn off asan-stack for clang-8 and earlier") > > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> > > Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Thanks! > [ Which tree are you planning to take it through? ] Gah, I was intending for it to go through -mm, then I cc'd neither Andrew nor linux-mm... :/ Andrew, do you want me to resend or can you grab it from LKML? > Note, arch/riscv/include/asm/kasan.h mentions KASAN_SHADOW_OFFSET in > comment (copied from arm64). Did RISC-V just forget to copy over the > Kconfig option? I do see it defined in that file as well but you are right that they did not copy the Kconfig logic, even though it was present in the tree when RISC-V KASAN was implemented. Perhaps they should so that they get access to the other flags in the "else" branch? > > --- > > scripts/Makefile.kasan | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan > > index 801c415bac59..b9e94c5e7097 100644 > > --- a/scripts/Makefile.kasan > > +++ b/scripts/Makefile.kasan > > @@ -33,10 +33,11 @@ else > > CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \ > > $(call cc-param,asan-globals=1) \ > > $(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \ > > - $(call cc-param,asan-stack=$(stack_enable)) \ > > $(call cc-param,asan-instrument-allocas=1) > > endif > > > > +CFLAGS_KASAN += $(call cc-param,asan-stack=$(stack_enable)) > > + > > endif # CONFIG_KASAN_GENERIC > > > > ifdef CONFIG_KASAN_SW_TAGS > > > > base-commit: 4057525736b159bd456732d11270af2cc49ec21f > > -- > > 2.33.0.514.g99c99ed825 > > > >
