From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14122 invoked by alias); 27 Feb 2006 14:05:55 -0000 Received: (qmail 14111 invoked by uid 22791); 27 Feb 2006 14:05:54 -0000 X-Spam-Status: No, hits=-1.2 required=5.0 tests=AWL,BAYES_20,DNS_FROM_RFC_ABUSE,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mtagate3.uk.ibm.com (HELO mtagate3.uk.ibm.com) (195.212.29.136) by sourceware.org (qpsmtpd/0.31) with ESMTP; Mon, 27 Feb 2006 14:05:52 +0000 Received: from d06nrmr1407.portsmouth.uk.ibm.com (d06nrmr1407.portsmouth.uk.ibm.com [9.149.38.185]) by mtagate3.uk.ibm.com (8.12.10/8.12.10) with ESMTP id k1RE5mTJ037914 for ; Mon, 27 Feb 2006 14:05:48 GMT Received: from d06av02.portsmouth.uk.ibm.com (d06av02.portsmouth.uk.ibm.com [9.149.37.228]) by d06nrmr1407.portsmouth.uk.ibm.com (8.12.10/NCO/VER6.8) with ESMTP id k1RE5xSh152826 for ; Mon, 27 Feb 2006 14:05:59 GMT Received: from d06av02.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av02.portsmouth.uk.ibm.com (8.12.11/8.13.3) with ESMTP id k1RE5moE029996 for ; Mon, 27 Feb 2006 14:05:48 GMT Received: from d06ml065.portsmouth.uk.ibm.com (d06ml065.portsmouth.uk.ibm.com [9.149.38.138]) by d06av02.portsmouth.uk.ibm.com (8.12.11/8.12.11) with ESMTP id k1RE5mVp029984 for ; Mon, 27 Feb 2006 14:05:48 GMT In-Reply-To: Subject: Re: Single-stepping with interrupts enabled. Sensitivity: To: fche@redhat.com (Frank Ch. Eigler) Cc: systemtap@sources.redhat.com X-Mailer: Lotus Notes Release 6.5.1IBM February 19, 2004 Message-ID: From: Richard J Moore Date: Mon, 27 Feb 2006 14:05:00 -0000 X-MIMETrack: Serialize by Router on D06ML065/06/M/IBM(Release 6.53HF247 | January 6, 2005) at 27/02/2006 14:05:58 MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2006-q1/txt/msg00641.txt.bz2 You can't do without post-handlers. SystemTap might not use them explicitly but post-handling of the single-step (in kprobes) is required whether or not a user handler is registered. For example for correcting the outcome of an instructions execution (certain adjustments may have to be made - E49, etc..); for handling exceptions from the single-stepped instruction correctly; for giving the correct 'logical' view at a higher level of a trace event following the generation of a recoverable page-fault on single-step; for correcting IF manipulating instructions where the state of the interrupt flag is not actually as the probed program logically thinks it is; for correcting the TRAP Flag for the same reasons as IF. There must be more. - - Richard J Moore IBM Advanced Linux Response Team - Linux Technology Centre MOBEX: 264807; Mobile (+44) (0)7739-875237 Office: (+44) (0)1962-817072 fche@redhat.com (Frank Ch. Eigler) To Sent by: Richard J Moore/UK/IBM@IBMGB fche@redhat.com cc systemtap@sources.redhat.com bcc 27/02/2006 13:51 Subject Re: Single-stepping with interrupts enabled. richardj_moore wrote: > [...] The problem is down to the need to save state over the > single-step, so that pre- and post-processing either side of the > single-step can be correctly associated with each other. [...] How much of this would be simplified if we did away with support for post_handlers (which we don't use in systemtap)? - FChE