Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 31/34] kbuild: add -fcf-protection=none when using retpoline flags | Date | Fri, 8 Nov 2019 19:50:38 +0100 |
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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) -- 2.20.1
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