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From: Borislav Petkov <bp@alien8.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
	Richard Narron <richard@aaazen.com>
Subject: Re: [PATCH] x86/alternative: Optimize single-byte NOPs at an arbitrary position
Date: Wed, 2 Jun 2021 12:37:32 +0200	[thread overview]
Message-ID: <YLdfbJBk20HIjfDE@zn.tnic> (raw)
In-Reply-To: <YLc+AniWgFBdMbX6@hirez.programming.kicks-ass.net>

On Wed, Jun 02, 2021 at 10:14:58AM +0200, Peter Zijlstra wrote:
> Who again insisted that wouldn't happen? :-)

Yours truly, ofc. :-P

> That's almost a proper comment, might as well finish it
> 
> /*
>  * optimize_nops_range() - Optimize a sequence of single byte NOPs (0x90)
>  * @instr: instruction byte stream
>  * @instrlen: length of the above
>  * @off: offset within @instr where the first NOP has been detected
>  *
>  * Return: number of NOPs found (and replaced)
>  */

Done.

> 	for (; i < instrlen && instr[i] == 0x90; i++)
> 		;
> 
> perhaps? (possibly too dense, up to you)

Yeah, let's leave it simple so that one can read it at a quick glance.

> > +
> > +	nnops = i - off;
> > +
> > +	if (nnops <= 1)
> > +		return nnops;
> 
> !nnops would be an error, no?

Yeah, just being overly cautious. It should not be 0 since we're being
called for the byte at offset being 0x90. But I have said "should not
be" before and have fallen flat on my face.

> We really needs that extra line?

Zapped.

> Anyway, irrespective of nits:
> 
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Thanks, all except one incorporated.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2021-06-02 10:38 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-01 21:21 Borislav Petkov
2021-06-02  8:14 ` Peter Zijlstra
2021-06-02 10:37   ` Borislav Petkov [this message]
2021-06-02 19:49 ` [tip: x86/urgent] " tip-bot2 for Borislav Petkov
2021-06-03 14:38 ` tip-bot2 for Borislav Petkov

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