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Date:   Mon, 13 Sep 2021 09:28:38 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Nathan Chancellor <nathan@kernel.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Joe Perches <joe@perches.com>, Arnd Bergmann <arnd@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>, llvm@lists.linux.dev,
        linux-kernel@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 10/10] vmlinux.lds.h: remove old check for GCC 4.9
Message-ID: <202109130927.6E5447B04C@keescook>
References: <20210910234047.1019925-1-ndesaulniers@google.com>
 <20210910234047.1019925-11-ndesaulniers@google.com>
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On Fri, Sep 10, 2021 at 04:40:47PM -0700, Nick Desaulniers wrote:
> Now that GCC 5.1 is the minimally supported version of GCC, we can
> effectively revert
> 
> commit 85c2ce9104eb ("sched, vmlinux.lds: Increase STRUCT_ALIGNMENT to
> 64 bytes for GCC-4.9")
> 
> Cc: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>  include/asm-generic/vmlinux.lds.h | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index aa50bf2959fe..f2984af2b85b 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -116,11 +116,7 @@
>   * GCC 4.5 and later have a 32 bytes section alignment for structures.
>   * Except GCC 4.9, that feels the need to align on 64 bytes.
>   */
> -#if __GNUC__ == 4 && __GNUC_MINOR__ == 9
> -#define STRUCT_ALIGNMENT 64
> -#else
>  #define STRUCT_ALIGNMENT 32
> -#endif
>  #define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT)

Yeah, looking at users of the macro, I think it's best to keep the macro
instead of hard-coding it everywhere.

Acked-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook