From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753625Ab3AJWnI (ORCPT ); Thu, 10 Jan 2013 17:43:08 -0500 Received: from mx1.redhat.com ([209.132.183.28]:26422 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753168Ab3AJWnH (ORCPT ); Thu, 10 Jan 2013 17:43:07 -0500 Message-ID: <50EF43F8.3040403@redhat.com> Date: Thu, 10 Jan 2013 14:43:04 -0800 From: Josh Stone User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Anton Arapov CC: Oleg Nesterov , Srikar Dronamraju , LKML , Frank Eigler Subject: Re: [RFC PATCH 5/6] uprobes: add bp_vaddr argument to consumer handler References: <1356088596-17858-1-git-send-email-anton@redhat.com> <1356088596-17858-6-git-send-email-anton@redhat.com> <20121222163545.GE18082@redhat.com> <20121222171329.GA20691@redhat.com> <20121223154910.GA7106@redhat.com> <20130108142715.GA16849@bandura.brq.redhat.com> In-Reply-To: <20130108142715.GA16849@bandura.brq.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 01/08/2013 06:27 AM, Anton Arapov wrote: > On Sun, Dec 23, 2012 at 04:49:10PM +0100, Oleg Nesterov wrote: >> On 12/22, Oleg Nesterov wrote: >>>> Just change regs->ip before calling ->handler(). >>> >>> Josh, Frank, will it work for you? >> >> Wait, probably I was confused by this patch and 4/6... >> >> To simplify, lets ignore the normal uprobes. Yes I still think that it >> would be better to set "regs->ip = orig_return_vaddr" before calling >> ->handler() and not pass it as an argument. >> >> But, probably uprobe_consumer also needs to know bp_vaddr? IOW, the >> address of the function which we are going to return from? In this case, >> yes, we also need another argument. And prepare_uretprobe/etc should >> be changed to record bp_vaddr passed from handle_swbp(). And >> uretprobe_run_handlers() should pass this bp_vaddr, not orig_return_vaddr. >> >> Or I am confused. >> >> Anton? > > Oleg, you are absolutely right and change the ip before calling the > ->handle is much better then what I 'invented'. > > I'm working on v2 to address this and other issues, will post it soon. For uprobes, systemtap wants regs->ip to be the real breakpoint address, and for uretprobes we want the original return address. With the utrace-based uprobes we would munge it by modifying regs->ip before continuing with the rest of our handler. If uprobes now wants to prepare regs->ip for us in the same way, I think that's fine. Josh