From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751867AbaEFRBp (ORCPT ); Tue, 6 May 2014 13:01:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11454 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750857AbaEFRBn (ORCPT ); Tue, 6 May 2014 13:01:43 -0400 Message-ID: <5369156C.4000602@redhat.com> Date: Tue, 06 May 2014 19:01:32 +0200 From: Denys Vlasenko User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Oleg Nesterov CC: linux-kernel@vger.kernel.org, Jim Keniston , Masami Hiramatsu , Srikar Dronamraju , Ingo Molnar Subject: Re: [PATCH 1/2] uprobes: add comment with insn opcodes, mnemonics and why we dont support them References: <1399314247-7368-1-git-send-email-dvlasenk@redhat.com> <20140505194100.GA26916@redhat.com> In-Reply-To: <20140505194100.GA26916@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/05/2014 09:41 PM, Oleg Nesterov wrote: > On 05/05, Denys Vlasenko wrote: >> >> + * Opcodes we'll probably never support: >> + * 6c-6f - ins,outs. SEGVs if used in userspace >> + * e4-e7 - in,out imm. SEGVs if used in userspace >> + * ec-ef - in,out acc. SEGVs if used in userspace > > Well. I have no idea why they are nacked, but this is not the reason. > > SEGVs are fine. Plus we have ioperm(). Noted. Oleg, can you clear for me the following - If the probed instruction triggers an "illegal insn" or "privileged insn" CPU exception - are we completely fine? Or there are some problems? how bad are they? Slightly wrong signal stack? Wrong EFLAGs on stack? Wrong address of failing insn?