* [PATCH] kbuild: add -fcf-protection=none to retpoline flags
@ 2019-07-09 18:49 Seth Forshee
2019-07-15 12:21 ` Masahiro Yamada
0 siblings, 1 reply; 2+ messages in thread
From: Seth Forshee @ 2019-07-09 18:49 UTC (permalink / raw)
To: Masahiro Yamada, Michal Marek; +Cc: linux-kbuild, linux-kernel
-mindirect-branch and -fcf-protection are not compatible, and
so kernel builds fail with a gcc build where -fcf-protection is
enabled by default. Add -fcf-protection=none to the retpoline
flags to fix this.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
---
Makefile | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/Makefile b/Makefile
index 3e4868a6498b..050f11d19777 100644
--- a/Makefile
+++ b/Makefile
@@ -636,6 +636,10 @@ RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk
RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline
RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))
RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG)))
+# -mindirect-branch is incompatible with -fcf-protection, so ensure the
+# latter is disabled
+RETPOLINE_CFLAGS += $(call cc-option,-fcf-protection=none,)
+RETPOLINE_VDSO_CFLAGS += $(call cc-option,-fcf-protection=none,)
export RETPOLINE_CFLAGS
export RETPOLINE_VDSO_CFLAGS
--
2.20.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] kbuild: add -fcf-protection=none to retpoline flags
2019-07-09 18:49 [PATCH] kbuild: add -fcf-protection=none to retpoline flags Seth Forshee
@ 2019-07-15 12:21 ` Masahiro Yamada
0 siblings, 0 replies; 2+ messages in thread
From: Masahiro Yamada @ 2019-07-15 12:21 UTC (permalink / raw)
To: Seth Forshee
Cc: Michal Marek, Linux Kbuild mailing list, Linux Kernel Mailing List
On Wed, Jul 10, 2019 at 3:49 AM Seth Forshee <seth.forshee@canonical.com> wrote:
>
> -mindirect-branch and -fcf-protection are not compatible, and
> so kernel builds fail with a gcc build where -fcf-protection is
> enabled by default. Add -fcf-protection=none to the retpoline
> flags to fix this.
>
> Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
> ---
Applied to linux-kbuild. Thanks.
> Makefile | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 3e4868a6498b..050f11d19777 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -636,6 +636,10 @@ RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk
> RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline
> RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))
> RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG)))
> +# -mindirect-branch is incompatible with -fcf-protection, so ensure the
> +# latter is disabled
> +RETPOLINE_CFLAGS += $(call cc-option,-fcf-protection=none,)
> +RETPOLINE_VDSO_CFLAGS += $(call cc-option,-fcf-protection=none,)
> export RETPOLINE_CFLAGS
> export RETPOLINE_VDSO_CFLAGS
>
> --
> 2.20.1
>
--
Best Regards
Masahiro Yamada
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