linux-kernel - Re: [PATCH] x86/alternatives: Fix alt_max

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Message-ID: <20171005145454.v52uzhzqtqshtksc@pd.tnic>
Date:   Thu, 5 Oct 2017 16:55:08 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Mathias Krause <minipli@...glemail.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86-ml <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Michael Matz <matz@...e.de>
Subject: Re: [PATCH] x86/alternatives: Fix alt_max_short macro to really be a
 max()

On Thu, Oct 05, 2017 at 02:35:33PM +0200, Mathias Krause wrote:
> Oh, btw., quoting its counter part from arch/x86/include/asm/alternative-asm.h:
> 
> /*
>  * max without conditionals. Idea adapted from:
>  * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
>  */
> #define alt_max_short(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
> 
> Note the "<"! ...comment is wrong, though the implementation works!

Ok, please fix that comment in alternative-asm.h and add

Reviewed-and-tested-by: Borislav Petkov <bp@...e.de>

to v2 before sending it.

Thanks!

-- 
Regards/Gruss,
    Boris.

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