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From: Joel Stanley <joel@jms.id.au>
Date: Wed, 25 Mar 2020 05:22:31 +0000
Message-ID: <CACPK8Xf70Yq2szW110G_2f2Q3J6inVqQY4Y-y0tggkVmT7tmfw@mail.gmail.com>
Subject: Re: [PATCH] powerpc/boot: Delete unneeded .globl _zimage_start
To: Fangrui Song <maskray@google.com>, Alan Modra <amodra@gmail.com>
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Cc: Nick Desaulniers <ndesaulniers@google.com>, linuxppc-dev@lists.ozlabs.org,
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On Wed, 25 Mar 2020 at 05:19, Fangrui Song <maskray@google.com> wrote:
>
> .globl sets the symbol binding to STB_GLOBAL while .weak sets the
> binding to STB_WEAK. They should not be used together. It is accidetal
> rather then intentional that GNU as let .weak override .globl while
> clang integrated assembler let the last win.
>
> Fixes: cd197ffcf10b "[POWERPC] zImage: Cleanup and improve zImage entry point"
> Fixes: ee9d21b3b358 "powerpc/boot: Ensure _zimage_start is a weak symbol"
> Link: https://github.com/ClangBuiltLinux/linux/issues/937
> Signed-off-by: Fangrui Song <maskray@google.com>
> Cc: Joel Stanley <joel@jms.id.au>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: clang-built-linux@googlegroups.com
> ---
>  arch/powerpc/boot/crt0.S | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S
> index 92608f34d312..1d83966f5ef6 100644
> --- a/arch/powerpc/boot/crt0.S
> +++ b/arch/powerpc/boot/crt0.S
> @@ -44,9 +44,6 @@ p_end:                .long   _end
>  p_pstack:      .long   _platform_stack_top
>  #endif
>
> -       .globl  _zimage_start
> -       /* Clang appears to require the .weak directive to be after the symbol
> -        * is defined. See https://bugs.llvm.org/show_bug.cgi?id=38921  */
>         .weak   _zimage_start
>  _zimage_start:

Your explanation makes sense to me. I've added Alan to cc for his review.

Reviewed-by: Joel Stanley <joel@jms.id.au>

Thanks for the patch.

Cheers,

Joel

>         .globl  _zimage_start_lib
> --
> 2.25.1.696.g5e7596f4ac-goog
>