From: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> [ Upstream commit 29be86d7f9cb18df4123f309ac7857570513e8bc ] 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 <seth.forshee@xxxxxxxxxxxxx> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- Makefile | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Makefile b/Makefile index 6b09890b170cd..43d0a98a9fe60 100644 --- a/Makefile +++ b/Makefile @@ -823,6 +823,12 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=strict-prototypes) # Prohibit date/time macros, which would make the build non-deterministic KBUILD_CFLAGS += $(call cc-option,-Werror=date-time) +# 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) -- 2.20.1
