On 10/14/21 2:50 AM, Nick Desaulniers wrote:

On Wed, Oct 13, 2021 at 11:03 AM Dan Li [off-list ref] wrote:

quoted

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 62c3c1d..da2da8c 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -81,7 +81,7 @@ config ARM64
         select ARCH_SUPPORTS_DEBUG_PAGEALLOC
         select ARCH_SUPPORTS_HUGETLBFS
         select ARCH_SUPPORTS_MEMORY_FAILURE
-       select ARCH_SUPPORTS_SHADOW_CALL_STACK if CC_HAVE_SHADOW_CALL_STACK
+       select ARCH_SUPPORTS_SHADOW_CALL_STACK if (CC_HAVE_SHADOW_CALL_STACK || GCC_PLUGIN_SHADOW_CALL_STACK)
         select ARCH_SUPPORTS_LTO_CLANG if CPU_LITTLE_ENDIAN
         select ARCH_SUPPORTS_LTO_CLANG_THIN
         select ARCH_SUPPORTS_CFI_CLANG

@@ -1062,7 +1062,7 @@ config ARCH_HAS_FILTER_PGPROT

  # Supported by clang >= 7.0
  config CC_HAVE_SHADOW_CALL_STACK
-       def_bool $(cc-option, -fsanitize=shadow-call-stack -ffixed-x18)
+       def_bool (CC_IS_CLANG && $(cc-option, -fsanitize=shadow-call-stack -ffixed-x18))

I guess since clang supported SCS since clang-7, but the minimally
supported version of clang according to
Documentation/process/changes.rst is 10.0.1, then this could be:

def_boot CC_IS_CLANG || $(cc-option, -fsanitize=shadow-call-stack -ffixed-x18)

Then we won't have to touch it again once SCS lands in upstream GCC,
as the cc-option test will start to pass?

Thanks Nick,

That sounds reasonable.