* Re: [PATCH] x86/Kconfig: Drop check for '-mabi=ms' for CONFIG_EFI_STUB
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
2022-10-17 15:03 ` Nathan Chancellor
2022-10-17 15:45 ` Ard Biesheuvel
2 siblings, 0 replies; 4+ messages in thread
From: Nick Desaulniers @ 2022-09-29 18:28 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Ard Biesheuvel, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Tom Rix, linux-kernel, llvm,
patches, stable
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
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] x86/Kconfig: Drop check for '-mabi=ms' for CONFIG_EFI_STUB
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
@ 2022-10-17 15:03 ` Nathan Chancellor
2022-10-17 15:45 ` Ard Biesheuvel
2 siblings, 0 replies; 4+ messages in thread
From: Nathan Chancellor @ 2022-10-17 15:03 UTC (permalink / raw)
To: Ard Biesheuvel, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86
Cc: H. Peter Anvin, Nick Desaulniers, Tom Rix, linux-kernel, llvm,
patches, stable
Hi x86 folks,
Would it be possible to pick this up for 6.1 so it can start filtering
into the stable trees? I know it came down towards the beginning of the
merge window so I understand the silence but I have had a couple of
people independently report this problem when they used a newer snapshot
of LLVM. This problem is not immediately obvious if you do not have a
previous configuration to diff against.
Cheers,
Nathan
On Thu, Sep 29, 2022 at 08:20:10AM -0700, Nathan Chancellor 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>
> ---
> 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
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] x86/Kconfig: Drop check for '-mabi=ms' for CONFIG_EFI_STUB
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
2022-10-17 15:03 ` Nathan Chancellor
@ 2022-10-17 15:45 ` Ard Biesheuvel
2 siblings, 0 replies; 4+ messages in thread
From: Ard Biesheuvel @ 2022-10-17 15:45 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
H. Peter Anvin, Nick Desaulniers, Tom Rix, linux-kernel, llvm,
patches, stable
On Thu, 29 Sept 2022 at 17:20, 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>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
I can take this as a EFI fix as well.
> ---
> 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
>
^ permalink raw reply [flat|nested] 4+ messages in thread