Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754880Ab0ARMOr (ORCPT ); Mon, 18 Jan 2010 07:14:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754627Ab0ARMOq (ORCPT ); Mon, 18 Jan 2010 07:14:46 -0500 Received: from casper.infradead.org ([85.118.1.10]:53074 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754406Ab0ARMOm (ORCPT ); Mon, 18 Jan 2010 07:14:42 -0500 Subject: Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP) From: Peter Zijlstra To: Avi Kivity Cc: ananth@in.ibm.com, Jim Keniston , Srikar Dronamraju , Ingo Molnar , Arnaldo Carvalho de Melo , utrace-devel , Frederic Weisbecker , Masami Hiramatsu , Maneesh Soni , Mark Wielaard , LKML In-Reply-To: <4B544F8E.1080603@redhat.com> References: <20100111122521.22050.3654.sendpatchset@srikar.in.ibm.com> <20100111122529.22050.32596.sendpatchset@srikar.in.ibm.com> <1263467289.4244.288.camel@laptop> <1263498366.4875.25.camel@localhost.localdomain> <1263546228.4244.343.camel@laptop> <20100115093831.GC26396@in.ibm.com> <1263549014.4244.374.camel@laptop> <4B53213C.9050303@redhat.com> <1263739939.557.20938.camel@twins> <4B5325CF.5000001@redhat.com> <1263740593.557.20967.camel@twins> <4B53661A.9090907@redhat.com> <1263800752.4283.19.camel@laptop> <4B543F93.3060509@redhat.com> <1263815072.4283.305.camel@laptop> <4B544D7C.2060708@redhat.com> <1263816396.4283.361.camel@laptop> <4B544F8E.1080603@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Mon, 18 Jan 2010 13:14:17 +0100 Message-ID: <1263816857.4283.381.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 928 Lines: 22 On Mon, 2010-01-18 at 14:09 +0200, Avi Kivity wrote: > On 01/18/2010 02:06 PM, Peter Zijlstra wrote: > > On Mon, 2010-01-18 at 14:01 +0200, Avi Kivity wrote: > > > >> Maybe you place no value on uprobes. But people who debug userspace > >> likely will see a reason. > >> > > I do see value in uprobes, I just don't like it mucking about with the > > address space. Nor does it appear required. > > > > Well, the alternatives are very unappealing. Emulation and > single-stepping are going to be very slow compared to a couple of jumps. With CPL2 or RPL on user segments the protection issue seems to be manageable for running the instructions from kernel space. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/