On Fri, Oct 08, 2021 at 11:46:55AM -0700, Palmer Dabbelt wrote: > On Thu, 23 Sep 2021 07:59:46 PDT (-0700), nathan@xxxxxxxxxx wrote: > > 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? > > Acked-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx> > > (assuming you still want it through somewhere else) Thanks, it is now in mainline as commit 19532869feb9 ("kasan: always respect CONFIG_KASAN_STACK"). > > > 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? > > Ya, looks like we just screwed this up. I'm seeing some warnings like > > cc1: warning: ‘-fsanitize=kernel-address’ with stack protection is not supported without ‘-fasan-shadow-offset=’ for this target Hmmm, I thought I did a GCC build with this change but I must not have :/ > which is how I ended up here, I'm assuming that's what you're talking about > here? LMK if you were planning on sending along a fix or if you want me to > go figure it out. I took a look at moving the logic into Kconfig like arm64 before sending this change and I did not really understand it well enough to do so. I think it would be best if you were able to do that so that nothing gets messed up. Cheers, Nathan
