From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756197Ab0AVSht (ORCPT ); Fri, 22 Jan 2010 13:37:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756171Ab0AVSht (ORCPT ); Fri, 22 Jan 2010 13:37:49 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39361 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756159Ab0AVShr (ORCPT ); Fri, 22 Jan 2010 13:37:47 -0500 Message-ID: <4B59F032.2060801@redhat.com> Date: Fri, 22 Jan 2010 13:36:34 -0500 From: Masami Hiramatsu User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-3.fc11 Thunderbird/3.0 MIME-Version: 1.0 To: Peter Zijlstra CC: Srikar Dronamraju , Ingo Molnar , Ananth N Mavinakayanahalli , utrace-devel , Frederic Weisbecker , Maneesh Soni , Jim Keniston , Avi Kivity , Pekka Enberg , Mel Gorman , "Paul E. McKenney" , LKML Subject: Re: [RFC] [PATCH 0/7] UBP, XOL and Uprobes [ Summary of Comments and actions to be taken ] References: <20100111122521.22050.3654.sendpatchset@srikar.in.ibm.com> <20100122070232.GA2975@linux.vnet.ibm.com> <1264183574.4283.1558.camel@laptop> In-Reply-To: <1264183574.4283.1558.camel@laptop> X-Enigmail-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra wrote: > On Fri, 2010-01-22 at 12:32 +0530, Srikar Dronamraju wrote: > >> 2. XOL vma vs Emulation vs Single Stepping Inline vs using Protection >> Rings. >> XOL VMA is an additional process address vma. This is >> opposition to add an additional vma without user actually >> requesting for the same. >> >> XOL vma and single stepping inline are the two architecture >> independent implementations. While other implementations are >> more architecture specific. Single stepping inline wouldnt go >> well with multithreaded process. >> >> Even though XOL vma has its own issues, we will go with it since >> other implementations seem to have more complications. >> >> we would look forward to implementing boosters later. >> Later on, if we come across another techniques with lesser >> side-effects than the XOL vma, we would switch to using them. > > How about modifying glibc to reserve like 64 bytes on the TLS structure > it has and storing the ins and possible boost jmp there? Since each > thread can only have a single trap at any one time that should be > enough. Hmm, it is a good idea. Well, we'll have a copy of original insn in kernel, but it could be simpler than managing XOL vma. :-) Thank you, -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division e-mail: mhiramat@redhat.com