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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2021-01-29 00:52:19 +0300 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-01-29 20:41:06 +0300 |
| commit | 20bf2b378729c4a0366a53e2018a0b70ace94bcd (patch) | |
| tree | 3d87eb862bfeccbf6172bdb04ca701b11857df25 | |
| parent | 6ee1d745b7c9fd573fba142a2efdad76a9f1cb04 (diff) | |
| download | linux-20bf2b378729c4a0366a53e2018a0b70ace94bcd.tar.xz | |
x86/build: Disable CET instrumentation in the kernel
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: 29be86d7f9cb ("kbuild: add -fcf-protection=none when using retpoline flags")
Reported-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay 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@treble
| -rw-r--r-- | Makefile | 6 | ||||
| -rw-r--r-- | arch/x86/Makefile | 3 |
2 files changed, 3 insertions, 6 deletions
@@ -948,12 +948,6 @@ 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 diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 7116da3980be..5857917f83ee 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -120,6 +120,9 @@ 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 |