From: Seth Forshee seth.forshee@canonical.com
[ 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@canonical.com Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com Signed-off-by: Sasha Levin sashal@kernel.org --- Makefile | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/Makefile b/Makefile index 62ce3766032c9..1d50905aaf425 100644 --- a/Makefile +++ b/Makefile @@ -840,6 +840,12 @@ 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)