提交 881dc3ea 编写于 作者: J Josh Poimboeuf 提交者: Zheng Zengkai

x86/build: Disable CET instrumentation in the kernel

stable inclusion
from stable-5.10.15
commit 2a2dfe6a319afb47448b28bedd65319aa59faef0
bugzilla: 48167

--------------------------------

commit 20bf2b37 upstream.

With retpolines disabled, some configurations of GCC, and specifically
the GCC versions 9 and 10 in Ubuntu will add Intel CET instrumentation
to the kernel by default. That breaks certain tracing scenarios by
adding a superfluous ENDBR64 instruction before the fentry call, for
functions which can be called indirectly.

CET instrumentation isn't currently necessary in the kernel, as CET is
only supported in user space. Disable it unconditionally and move it
into the x86's Makefile as CET/CFI... enablement should be a per-arch
decision anyway.

 [ bp: Massage and extend commit message. ]

Fixes: 29be86d7 ("kbuild: add -fcf-protection=none when using retpoline flags")
Reported-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Tested-by: NNikolay Borisov <nborisov@suse.com>
Cc: <stable@vger.kernel.org>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Link: https://lkml.kernel.org/r/20210128215219.6kct3h2eiustncws@trebleSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
上级 19d76e3d
无相关合并请求
......@@ -950,12 +950,6 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
# change __FILE__ to the relative path from the srctree
KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
# ensure -fcf-protection is disabled when using retpoline as it is
# incompatible with -mindirect-branch=thunk-extern
ifdef CONFIG_RETPOLINE
KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
endif
# include additional Makefiles when needed
include-y := scripts/Makefile.extrawarn
include-$(CONFIG_KASAN) += scripts/Makefile.kasan
......
......@@ -127,6 +127,9 @@ else
KBUILD_CFLAGS += -mno-red-zone
KBUILD_CFLAGS += -mcmodel=kernel
# Intel CET isn't enabled in the kernel
KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
endif
ifdef CONFIG_X86_X32
......
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