Re: [PATCH 1/5] compiler_types.h: Move __nocfi out of compiler-specific header

[Nathan Chancellor <nathan@kernel.org>]

On Mon, Aug 25, 2025 at 07:25:48AM -0700, Kees Cook wrote:
> From: Kees Cook <kees@outflux.net>
> 
> Prepare for GCC KCFI support and move the __nocfi attribute from
> compiler-clang.h to compiler_types.h. This was already effectively gated
> by CONFIG_CFI_CLANG, so this remains safe for non-KCFI GCC builds.
> 
> Signed-off-by: Kees Cook <kees@outflux.net>

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

> ---
>  include/linux/compiler-clang.h | 5 -----
>  include/linux/compiler_types.h | 4 +++-
>  2 files changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
> index fa4ffe037bc7..7a4568e421dc 100644
> --- a/include/linux/compiler-clang.h
> +++ b/include/linux/compiler-clang.h
> @@ -96,11 +96,6 @@
>  # define __noscs	__attribute__((__no_sanitize__("shadow-call-stack")))
>  #endif
>  
> -#if __has_feature(kcfi)
> -/* Disable CFI checking inside a function. */
> -#define __nocfi		__attribute__((__no_sanitize__("kcfi")))
> -#endif
> -
>  /*
>   * Turn individual warnings and errors on and off locally, depending
>   * on version.
> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
> index 16755431fc11..a910f9fa5341 100644
> --- a/include/linux/compiler_types.h
> +++ b/include/linux/compiler_types.h
> @@ -432,7 +432,9 @@ struct ftrace_likely_data {
>  # define __noscs
>  #endif
>  
> -#ifndef __nocfi
> +#if defined(CONFIG_CFI_CLANG)

I tend to prefer '#ifdef' for single symbols.

> +# define __nocfi		__attribute__((__no_sanitize__("kcfi")))
> +#else
>  # define __nocfi
>  #endif
>  
> -- 
> 2.34.1
>