From 29be86d7f9cb18df4123f309ac7857570513e8bc Mon Sep 17 00:00:00 2001 From: Seth Forshee Date: Wed, 17 Jul 2019 11:06:26 -0500 Subject: [PATCH] kbuild: add -fcf-protection=none when using retpoline flags The gcc -fcf-protection=branch option is not compatible with -mindirect-branch=thunk-extern. The latter is used when CONFIG_RETPOLINE is selected, and this will fail to build with a gcc which has -fcf-protection=branch enabled by default. Adding -fcf-protection=none when building with retpoline enabled prevents such build failures. Signed-off-by: Seth Forshee Signed-off-by: Masahiro Yamada --- Makefile | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Makefile b/Makefile index 86d26c0ad9a9..fd6f7949bc1a 100644 --- a/Makefile +++ b/Makefile @@ -882,6 +882,12 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init) # change __FILE__ to the relative path from the srctree KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=) +# ensure -fcf-protection is disabled when using retpoline as it is +# incompatible with -mindirect-branch=thunk-extern +ifdef CONFIG_RETPOLINE +KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none) +endif + # use the deterministic mode of AR if available KBUILD_ARFLAGS := $(call ar-option,D)