From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751805AbaDPEEJ (ORCPT ); Wed, 16 Apr 2014 00:04:09 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:41824 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750783AbaDPEEH (ORCPT ); Wed, 16 Apr 2014 00:04:07 -0400 Message-ID: <534E0124.70700@oracle.com> Date: Wed, 16 Apr 2014 00:03:48 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: "H. Peter Anvin" , Masami Hiramatsu CC: vegard.nossum@oracle.com, penberg@kernel.org, jamie.iles@oracle.com, mingo@redhat.com, tglx@linutronix.de, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@vger.kernel.org Subject: Re: [PATCH 3/4] x86/insn: Extract more information about instructions References: <1397497450-6440-1-git-send-email-sasha.levin@oracle.com> <1397497450-6440-3-git-send-email-sasha.levin@oracle.com> <534CA38C.80501@hitachi.com> <534D4BF3.3020102@oracle.com> <534DF868.2020901@zytor.com> <534DFD61.4070700@oracle.com> <534DFEDC.8090503@zytor.com> In-Reply-To: <534DFEDC.8090503@zytor.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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