[PATCH v21 1/7] x86/cet/ibt: Update Kconfig for user-mode Indirect Branch Tracking

[Yu-cheng Yu]

Indirect branch tracking is a hardware security feature that verifies near
indirect call/jump instructions arrive at intended targets, which are
labeled by the compiler with ENDBR opcodes.  If such instructions reach
unlabeled locations, the processor raises control-protection faults.

Check the compiler is up-to-date at config time.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 arch/x86/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cafa4a2c1d2d..5e157031bf82 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1963,6 +1963,7 @@ config X86_CET
 	def_bool n
 	depends on AS_WRUSS
 	depends on ARCH_HAS_SHADOW_STACK
+	depends on $(cc-option,-fcf-protection)
 	select ARCH_USES_HIGH_VMA_FLAGS
 	select ARCH_MAYBE_MKWRITE
 	select ARCH_USE_GNU_PROPERTY
-- 
2.21.0