linux-kernel - Re: [PATCH v2 1/2] x86/build: Remove -ffreestanding on i386 with GCC

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Message-ID: <20250308091746.GA707537@ax162>
Date: Sat, 8 Mar 2025 10:17:46 +0100
From: Nathan Chancellor <nathan@...nel.org>
To: Kees Cook <kees@...nel.org>
Cc: Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	Paul Moore <paul@...l-moore.com>, James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org,
	linux-security-module@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH v2 1/2] x86/build: Remove -ffreestanding on i386 with GCC

On Fri, Mar 07, 2025 at 08:29:25PM -0800, Kees Cook wrote:
> The use of -ffreestanding is a leftover that is only needed for certain
> versions of Clang. Adjust this to be Clang-only. A later patch will make
> this a versioned check.
> 
> Signed-off-by: Kees Cook <kees@...nel.org>

This could also adjust the comment but it is probably not that big of a
deal since the "temporary" is already pretty stale.

Reviewed-by: Nathan Chancellor <nathan@...nel.org>

> ---
> Cc: Nathan Chancellor <nathan@...nel.org>
> Cc: Nick Desaulniers <nick.desaulniers+lkml@...il.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: x86@...nel.org
> Cc: "H. Peter Anvin" <hpa@...or.com>
> ---
>  arch/x86/Makefile | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index 5b773b34768d..d25ed25fb7d9 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -137,8 +137,10 @@ ifeq ($(CONFIG_X86_32),y)
>          include $(srctree)/arch/x86/Makefile_32.cpu
>          KBUILD_CFLAGS += $(cflags-y)
>  
> +    ifeq ($(CONFIG_CC_IS_CLANG),y)
>          # temporary until string.h is fixed
>          KBUILD_CFLAGS += -ffreestanding
> +    endif
>  
>      ifeq ($(CONFIG_STACKPROTECTOR),y)
>          ifeq ($(CONFIG_SMP),y)
> -- 
> 2.34.1
>