Re: [PATCH 3/4] x86/boot: use -fno-builtin-bcmp

[Kees Cook]

On Mon, Aug 17, 2020 at 03:02:11PM -0700, Nick Desaulniers wrote:
> We're reverting
> commit 5f074f3e192f ("lib/string.c: implement a basic bcmp")
> in favor of -fno-builtin-bcmp. Remove the additional definition here,
> too.
> 
> arch/x86/purgatory/Makefile uses -ffreestanding, so there's no risk of
> this libcall optimization occurring for arch/x86/boot/purgatory.ro.
> 
> arch/x86/boot/Makefile resets KBUILD_CFLAGS, so make sure to reset this
> flag that was set for the top level Makefile.
> 
> Fixes: 4ce97317f41d ("x86/purgatory: Do not use __builtin_memcpy and __builtin_memset")
> Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-- 
Kees Cook