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 6af1c13d8753b..729467fe0933f 100644 --- a/Makefile +++ b/Makefile @@ -835,6 +835,12 @@ 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) -- 2.20.1
