Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755039Ab0ASSGU (ORCPT ); Tue, 19 Jan 2010 13:06:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754459Ab0ASSGT (ORCPT ); Tue, 19 Jan 2010 13:06:19 -0500 Received: from mail-fx0-f215.google.com ([209.85.220.215]:37339 "EHLO mail-fx0-f215.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754147Ab0ASSGS (ORCPT ); Tue, 19 Jan 2010 13:06:18 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=Il9NpxrLH+MeXoXekBzUOwyMAFGbckpt/8ifgDz99tn/4S9uKN1dHEOC8iA3efMgNb 5dU+0vzHBNmUuOd+l6+pPMnYYSX9f7On4LLEefrX8sm+9/aSjWxIX4RBoCUppfOEKuWP yHjeuEhKEb7ebUsaWv69o9HLyQSwifMDT9zDI= Date: Tue, 19 Jan 2010 19:06:12 +0100 From: Frederic Weisbecker To: Jim Keniston Cc: Avi Kivity , Pekka Enberg , Srikar Dronamraju , Peter Zijlstra , ananth@in.ibm.com, Ingo Molnar , Arnaldo Carvalho de Melo , utrace-devel , Masami Hiramatsu , Maneesh Soni , Mark Wielaard , LKML Subject: Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP) Message-ID: <20100119180610.GA11005@nowhere> References: <4B544F8E.1080603@redhat.com> <84144f021001180413w76a8ca2axb0b9f07ee4dea67e@mail.gmail.com> <4B545146.3080001@redhat.com> <20100118124419.GC1628@linux.vnet.ibm.com> <84144f021001180451k2a84f17x3dc24796fea986c9@mail.gmail.com> <4B5459CA.9060603@redhat.com> <4B545ACF.40203@cs.helsinki.fi> <1263852957.2266.38.camel@localhost.localdomain> <4B556855.6040800@redhat.com> <1263923265.4998.28.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1263923265.4998.28.camel@localhost.localdomain> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1211 Lines: 26 On Tue, Jan 19, 2010 at 09:47:45AM -0800, Jim Keniston wrote: > > Do you have plans for a variant > > that's completely in userspace? > > I don't know of any such plans, but I'd be interested to read more of > your thoughts here. As I understand it, you've suggested replacing the > probed instruction with a jump into an instrumentation vma (the XOL > area, or something similar). Masami has demonstrated -- through his > djprobes enhancement to kprobes -- that this can be done for many x86 > instructions. > > What does the code in the jumped-to vma do? Is the instrumentation code > that corresponds to the uprobe handlers encoded in an ad hoc .so? Once the instrumentation is requested by a process that is not the instrumented one, this looks impossible to set a uprobe without a minimal voluntary collaboration from the instrumented process (events sent through IPC or whatever). So that looks too limited, this is not anymore a true dynamic uprobe. -- 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/