From 0b53c374b9eff2255a386f1f1cfb9a928e52a5ae Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 14 Jun 2022 23:15:36 +0200 Subject: x86/retpoline: Use -mfunction-return Utilize -mfunction-return=thunk-extern when available to have the compiler replace RET instructions with direct JMPs to the symbol __x86_return_thunk. This does not affect assembler (.S) sources, only C sources. -mfunction-return=thunk-extern has been available since gcc 7.3 and clang 15. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Reviewed-by: Nick Desaulniers Reviewed-by: Josh Poimboeuf Tested-by: Nick Desaulniers Signed-off-by: Borislav Petkov --- arch/x86/Makefile | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/Makefile') diff --git a/arch/x86/Makefile b/arch/x86/Makefile index a74886aed349..6e16057737e5 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -15,11 +15,13 @@ endif ifdef CONFIG_CC_IS_GCC RETPOLINE_CFLAGS := $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register) RETPOLINE_CFLAGS += $(call cc-option,-mindirect-branch-cs-prefix) +RETPOLINE_CFLAGS += $(call cc-option,-mfunction-return=thunk-extern) RETPOLINE_VDSO_CFLAGS := $(call cc-option,-mindirect-branch=thunk-inline -mindirect-branch-register) endif ifdef CONFIG_CC_IS_CLANG RETPOLINE_CFLAGS := -mretpoline-external-thunk RETPOLINE_VDSO_CFLAGS := -mretpoline +RETPOLINE_CFLAGS += $(call cc-option,-mfunction-return=thunk-extern) endif export RETPOLINE_CFLAGS export RETPOLINE_VDSO_CFLAGS -- cgit