x86/build: Disable CET instrumentation in the kernel
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: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 Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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08143844
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