linux-kernel - Re: [PATCH v2.1 02/23] x86/mmx_32: Remove X86_USE

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Date:   Tue, 16 Nov 2021 19:25:43 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.orgg, linux-kernel@...r.kernel.org, jpoimboe@...hat.com,
        mark.rutland@....com, dvyukov@...gle.com, seanjc@...gle.com,
        pbonzini@...hat.com, mbenes@...e.cz
Subject: Re: [PATCH v2.1 02/23] x86/mmx_32: Remove X86_USE_3DNOW

On Mon, Nov 15, 2021 at 05:54:37PM +0100, Peter Zijlstra wrote:
> 
> 
> The alternative (har har) for this patch is the below, which seems
> favoured by Boris.
> 
> ---
> Subject: x86/mmx_32: Remove X86_USE_3DNOW
> From: Peter Zijlstra <peterz@...radead.org>
> Date: Mon Nov 15 17:46:39 CET 2021
> 
> This code puts an exception table entry on the PREFETCH instruction to
> overwrite it with a JMP.d8 when it triggers an exception. Except of
> course, our code is no longer writable, also SMP.
> 
> Instead of fixing this broken mess, simply take it out.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
>  arch/x86/Kconfig                               |    2 
>  arch/x86/Kconfig.cpu                           |    4 
>  arch/x86/include/asm/mmx.h                     |   15 
>  arch/x86/include/asm/page_32.h                 |   14 
>  arch/x86/include/asm/required-features.h       |    4 
>  arch/x86/include/asm/string_32.h               |   33 --
>  arch/x86/lib/Makefile                          |    1 
>  arch/x86/lib/memcpy_32.c                       |    4 
>  arch/x86/lib/mmx_32.c                          |  388 -------------------------
>  arch/x86/lib/usercopy_32.c                     |    1 
>  tools/arch/x86/include/asm/required-features.h |    4 
>  11 files changed, 1 insertion(+), 469 deletions(-)

Acked-by: Borislav Petkov <bp@...e.de>

Obviously. :-)

-- 
Regards/Gruss,
    Boris.

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