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authorArd Biesheuvel <ardb@kernel.org>2022-10-27 18:59:07 +0300
committerWill Deacon <will@kernel.org>2022-11-09 21:06:35 +0300
commit9beccca0984022a844850e32f0d7dd80d4a225de (patch)
treef9a9128498d40dee1958e15b212707872f039e38 /arch/Kconfig
parent68c76ad4a9571a2b603665c85cf8229bcf04982a (diff)
downloadlinux-9beccca0984022a844850e32f0d7dd80d4a225de.tar.xz
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 'arch/Kconfig')
-rw-r--r--arch/Kconfig7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 8f138e580d1a..072a1b39e3af 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -651,6 +651,13 @@ config SHADOW_CALL_STACK
reading and writing arbitrary memory may be able to locate them
and hijack control flow by modifying the stacks.
+config DYNAMIC_SCS
+ bool
+ help
+ Set by the arch code if it relies on code patching to insert the
+ shadow call stack push and pop instructions rather than on the
+ compiler.
+
config LTO
bool
help