linux-kernel - Re: [PATCH v3] x86, mem: move memmove to out of line assembler

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Message-ID: <202209271413.314FCFC3@keescook>
Date:   Tue, 27 Sep 2022 14:14:22 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     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>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        llvm@...ts.linux.dev, Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH v3] x86, mem: move memmove to out of line assembler

On Tue, Sep 27, 2022 at 02:02:48PM -0700, Nick Desaulniers wrote:
> [...]
> Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
> ---
> Changes v2 -> v3:
> * Fix bug I introduced in v1 when I changed one of temp register
>   operands for one of the two instructions performing a mem to mem swap,
>   but not the other instruction's operand, and discovered by Kees.
>   Verified KUnit memcpy tests are passing via:
>   $ ./tools/testing/kunit/kunit.py run --arch=i386 --make_options LLVM=1
>   $ ./tools/testing/kunit/kunit.py run --arch=i386
>   Fixed by using symbolic identifiers rather than open coded registers
>   for the less-than-word-size temporary registers.
> * Expand the comment about callee saved registers on i386 with a
>   reference to the psABI.

Thanks! This looks good.

Reviewed-by: Kees Cook <keescook@...omium.org>
Tested-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook