Re: [PATCH v8 01/12] add support for Clang's Shadow Call Stack (SCS)

diff --git a/arch/Kconfig b/arch/Kconfig
index 98de654b79b3..66b34fd0df54 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig

@@ -526,6 +526,40 @@ config STACKPROTECTOR_STRONG
 	  about 20% of all kernel functions, which increases the kernel code
 	  size by about 2%.
 
+config ARCH_SUPPORTS_SHADOW_CALL_STACK
+	bool
+	help
+	  An architecture should select this if it supports Clang's Shadow
+	  Call Stack, has asm/scs.h, and implements runtime support for shadow
+	  stack switching.
+
+config SHADOW_CALL_STACK
+	bool "Clang Shadow Call Stack"
+	depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
+	help
+	  This option enables Clang's Shadow Call Stack, which uses a
+	  shadow stack to protect function return addresses from being
+	  overwritten by an attacker. More information can be found from

+	  Clang's documentation:
+
+	    https://clang.llvm.org/docs/ShadowCallStack.html
+
+	  Note that security guarantees in the kernel differ from the ones
+	  documented for user space. The kernel must store addresses of shadow
+	  stacks used by other tasks and interrupt handlers in memory, which
+	  means an attacker capable reading and writing arbitrary memory may

+	  be able to locate them and hijack control flow by modifying shadow
+	  stacks that are not currently in use.
+
+config SHADOW_CALL_STACK_VMAP
+	bool "Use virtually mapped shadow call stacks"
+	depends on SHADOW_CALL_STACK
+	help
+	  Use virtually mapped shadow call stacks. Selecting this option
+	  provides better stack exhaustion protection, but increases per-thread
+	  memory consumption as a full page is allocated for each shadow stack.
+
+
 config HAVE_ARCH_WITHIN_STACK_FRAMES
 	bool
 	help