linux-kernel - Re: [PATCH 3/4] x86/insn: Extract more information about instructions

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Message-ID: <16fe17b6-c185-419e-9b7c-3d2a89b883cd@email.android.com>
Date:	Tue, 15 Apr 2014 21:31:29 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Sasha Levin <sasha.levin@...cle.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
CC:	vegard.nossum@...cle.com, penberg@...nel.org,
	jamie.iles@...cle.com, mingo@...hat.com, tglx@...utronix.de,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-mm@...r.kernel.org
Subject: Re: [PATCH 3/4] x86/insn: Extract more information about instructions

I really wonder if it makes sense...

On April 15, 2014 9:03:48 PM PDT, Sasha Levin <sasha.levin@...cle.com> wrote:
>On 04/15/2014 11:54 PM, H. Peter Anvin wrote:
>> On 04/15/2014 08:47 PM, Sasha Levin wrote:
>>> > 
>>> > Yes, if kmemcheck for some reason needs to figure out if an
>instruction
>>> > is a MOV variant we'll need to list quite a few mnemonics, but
>that list
>>> > will be much shorter and more readable than a corresponding list
>of opcodes.
>>> > 
>> You're completely missing my point.  If you are looking at MOV, with
>> 80%+ probability you're doing something very, very wrong, because you
>> will be including instructions that do something completely different
>> from what you thought.
>> 
>> This is true for a lot of the x86 instructions.
>
>Right, but assuming that the AND example I presented earlier makes
>sense, I
>can't create mnemonic entries only for instructions where doing so
>would
>"probably" be right.
>
>If there are use cases where working with mnemonics is correct, we
>should
>be doing that in kmemcheck. If the way kmemcheck deals with mnemonics
>is
>incorrect we should go ahead and fix kmemcheck.
>
>
>Thanks,
>Sasha

-- 
Sent from my mobile phone.  Please pardon brevity and lack of formatting.
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