From f627b51aaa041cba715b59026cf2d9cb1476c7ed Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 29 Jul 2025 16:41:00 -0700 Subject: compiler_types: Provide __no_kstack_erase to disable coverage only on Clang In order to support Clang's stack depth tracking (for Linux's kstack_erase feature), the coverage sanitizer needed to be disabled for __init (and __head) section code. Doing this universally (i.e. for GCC too) created a number of unexpected problems, ranging from changes to inlining logic to failures to DCE code on earlier GCC versions. Since this change is only needed for Clang, specialize it so that GCC doesn't see the change as it isn't needed there (the GCC implementation of kstack_erase uses a GCC plugin that removes stack depth tracking instrumentation from __init sections during a late pass in the IR). Successfully build and boot tested with GCC 12 and Clang 22. Fixes: 381a38ea53d2 ("init.h: Disable sanitizer coverage for __init and __head") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202507270258.neWuiXLd-lkp@intel.com/ Reported-by: syzbot+5245cb609175fb6e8122@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6888d004.a00a0220.26d0e1.0004.GAE@google.com/ Reviewed-by: Nathan Chancellor Reviewed-by: Marco Elver Link: https://lore.kernel.org/r/20250729234055.it.233-kees@kernel.org Signed-off-by: Kees Cook --- include/linux/compiler-clang.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/compiler-clang.h') diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index 4fc8e26914ad..fa4ffe037bc7 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -89,6 +89,9 @@ #define __no_sanitize_coverage #endif +/* Only Clang needs to disable the coverage sanitizer for kstack_erase. */ +#define __no_kstack_erase __no_sanitize_coverage + #if __has_feature(shadow_call_stack) # define __noscs __attribute__((__no_sanitize__("shadow-call-stack"))) #endif -- cgit