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authorArd Biesheuvel <ardb@kernel.org>2022-10-27 17:59:07 +0200
committerWill Deacon <will@kernel.org>2022-11-09 18:06:35 +0000
commit9beccca0984022a844850e32f0d7dd80d4a225de (patch)
treef9a9128498d40dee1958e15b212707872f039e38 /Makefile
parent68c76ad4a9571a2b603665c85cf8229bcf04982a (diff)
scs: add support for dynamic shadow call stacks
In order to allow arches to use code patching to conditionally emit the shadow stack pushes and pops, rather than always taking the performance hit even on CPUs that implement alternatives such as stack pointer authentication on arm64, add a Kconfig symbol that can be set by the arch to omit the SCS codegen itself, without otherwise affecting how support code for SCS and compiler options (for register reservation, for instance) are emitted. Also, add a static key and some plumbing to omit the allocation of shadow call stack for dynamic SCS configurations if SCS is disabled at runtime. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sami Tolvanen <samitolvanen@google.com> Link: https://lore.kernel.org/r/20221027155908.1940624-3-ardb@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile2
1 files changed, 2 insertions, 0 deletions
diff --git a/Makefile b/Makefile
index ac2ec990422d..69b40b629f3c 100644
--- a/Makefile
+++ b/Makefile
@@ -966,8 +966,10 @@ LDFLAGS_vmlinux += --gc-sections
endif
ifdef CONFIG_SHADOW_CALL_STACK
+ifndef CONFIG_DYNAMIC_SCS
CC_FLAGS_SCS := -fsanitize=shadow-call-stack
KBUILD_CFLAGS += $(CC_FLAGS_SCS)
+endif
export CC_FLAGS_SCS
endif