From: Nick Desaulniers <ndesaulniers@google.com>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Tom Rix <trix@redhat.com>,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
patches@lists.linux.dev, stable@vger.kernel.org
Subject: Re: [PATCH] x86/Kconfig: Drop check for '-mabi=ms' for CONFIG_EFI_STUB
Date: Thu, 29 Sep 2022 11:28:14 -0700 [thread overview]
Message-ID: <CAKwvOdn61SYD81r5opTN1N8MAWe5YObPJ8wELei1qOySsoxJyA@mail.gmail.com> (raw)
In-Reply-To: <20220929152010.835906-1-nathan@kernel.org>
On Thu, Sep 29, 2022 at 8:20 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> A recent change in LLVM made CONFIG_EFI_STUB unselectable because it no
> longer pretends to support '-mabi=ms', breaking the dependency in
> Kconfig. Lack of CONFIG_EFI_STUB can prevent kernels from booting via
> EFI in certain circumstances.
>
> This check was added by commit 8f24f8c2fc82 ("efi/libstub: Annotate
> firmware routines as __efiapi") to ensure that '__attribute__((ms_abi))'
> was available, as '-mabi=ms' is not actually used in any cflags.
> According to the GCC documentation, this attribute has been supported
> since GCC 4.4.7. The kernel currently requires GCC 5.1 so this check is
> not necessary; even when that change landed in 5.6, the kernel required
> GCC 4.9 so it was unnecessary then as well. Clang supports
> '__attribute__((ms_abi))' for all versions that are supported for
> building the kernel so no additional check is needed. Remove the
> 'depends on' line altogether to allow CONFIG_EFI_STUB to be selected
> when CONFIG_EFI is enabled, regardless of compiler.
>
> Cc: stable@vger.kernel.org
> Fixes: 8f24f8c2fc82 ("efi/libstub: Annotate firmware routines as __efiapi")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1725
> Link: https://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/Function-Attributes.html
> Link: https://github.com/llvm/llvm-project/commit/d1ad006a8f64bdc17f618deffa9e7c91d82c444d
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
> arch/x86/Kconfig | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index f9920f1341c8..81012154d9ed 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1956,7 +1956,6 @@ config EFI
> config EFI_STUB
> bool "EFI stub support"
> depends on EFI
> - depends on $(cc-option,-mabi=ms) || X86_32
> select RELOCATABLE
> help
> This kernel feature allows a bzImage to be loaded directly
>
> base-commit: f76349cf41451c5c42a99f18a9163377e4b364ff
> --
> 2.37.3
>
--
Thanks,
~Nick Desaulniers
next prev parent reply other threads:[~2022-09-29 18:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-29 15:20 [PATCH] x86/Kconfig: Drop check for '-mabi=ms' for CONFIG_EFI_STUB Nathan Chancellor
2022-09-29 18:28 ` Nick Desaulniers [this message]
2022-10-17 15:03 ` Nathan Chancellor
2022-10-17 15:45 ` Ard Biesheuvel
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