linux-kernel - Re: [PATCH] efi/libstub: Disable some warnings for x86{,

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Date:   Tue, 6 Nov 2018 15:16:31 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     sedat.dilek@...il.com
Cc:     Nathan Chancellor <natechancellor@...il.com>,
        linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH] efi/libstub: Disable some warnings for x86{,_64}

On 6 November 2018 at 14:15, Sedat Dilek <sedat.dilek@...il.com> wrote:
> On Mon, Nov 5, 2018 at 1:52 PM Ard Biesheuvel <ard.biesheuvel@...aro.org> wrote:
>>
>> On 24 October 2018 at 09:22, Sedat Dilek <sedat.dilek@...il.com> wrote:
>> > On Tue, Oct 23, 2018 at 7:53 PM Nathan Chancellor
>> > <natechancellor@...il.com> wrote:
>> >>
>> >> On Fri, Oct 12, 2018 at 06:03:49PM -0700, Nathan Chancellor wrote:
>> >> > When building the kernel with Clang, some disabled warnings appear
>> >> > because this Makefile overrides KBUILD_CFLAGS for x86{,_64}. Add them to
>> >> > this list so that the build is clean again.
>> >> >
>> >> > -Wpointer-sign was disabled for the whole kernel before the beginning
>> >> > of git history.
>> >> >
>> >> > -Waddress-of-packed-member was disabled for the whole kernel in
>> >> > commit bfb38988c51e ("kbuild: clang: Disable 'address-of-packed-member'
>> >> > warning") and for x86/boot/compressed in commit 20c6c1890455 ("x86/boot:
>> >> > Disable the address-of-packed-member compiler warning").
>> >> >
>> >> > -Wgnu was disabled for the whole kernel in commit 61163efae020 ("kbuild:
>> >> > LLVMLinux: Add Kbuild support for building kernel with Clang") and for
>> >> > x86/boot/compressed in commit 6c3b56b19730 ("x86/boot: Disable Clang
>> >> > warnings about GNU extensions").
>> >> >
>> >> > Link: https://github.com/ClangBuiltLinux/linux/issues/112
>> >> > Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
>> >> > ---
>> >> >
>> >> > Nick expressed concern that this Makefile is overwriting KBUILD_CFLAGS
>> >> > and suggested potentially rewriting the x86 portion of this Makefile to
>> >> > behave like the arm/arm64 one where problematic flags are filtered out.
>> >> > While that comes to fruition, it would be nice for this folder to behave
>> >> > like the rest of the kernel when it comes to this warnings so that the
>> >> > build is cleaner, thus this patch.
>> >> >
>> >> >  drivers/firmware/efi/libstub/Makefile | 5 ++++-
>> >> >  1 file changed, 4 insertions(+), 1 deletion(-)
>> >> >
>> >> > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
>> >> > index c51627660dbb..d9845099635e 100644
>> >> > --- a/drivers/firmware/efi/libstub/Makefile
>> >> > +++ b/drivers/firmware/efi/libstub/Makefile
>> >> > @@ -9,7 +9,10 @@ cflags-$(CONFIG_X86_32)              := -march=i386
>> >> >  cflags-$(CONFIG_X86_64)              := -mcmodel=small
>> >> >  cflags-$(CONFIG_X86)         += -m$(BITS) -D__KERNEL__ -O2 \
>> >> >                                  -fPIC -fno-strict-aliasing -mno-red-zone \
>> >> > -                                -mno-mmx -mno-sse -fshort-wchar
>> >> > +                                -mno-mmx -mno-sse -fshort-wchar \
>> >> > +                                -Wno-pointer-sign \
>> >> > +                                $(call cc-disable-warning, address-of-packed-member) \
>> >> > +                                $(call cc-disable-warning, gnu)
>> >> >
>> >> >  # arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
>> >> >  # disable the stackleak plugin
>> >> > --
>> >> > 2.19.1
>> >> >
>> >>
>> >> + Sedat for review/testing.
>> >
>> > Thanks Nathan.
>> >
>> > Reviewed-by: Sedat Dilek <sedat.dilek@...il.com>
>> > Tested-by: Sedat Dilek <sedat.dilek@...il.com>
>> > [ Reported-by: Sedat Dilek <sedat.dilek@...il.com> ]
>> > [ See duplicate "arch/x86/include/asm/processor.h: Warning
>> > -Waddress-of-packed-member "
>> > <https://github.com/ClangBuiltLinux/linux/issues/234> ]
>> >
>>
>> Queued in efi/next
>>
>
> Thanks Ard.
> This means efi-for-4.21 / efi-for-5.0?
>

Yes