From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13201 invoked by alias); 12 Oct 2012 05:59:48 -0000 Received: (qmail 13192 invoked by uid 22791); 12 Oct 2012 05:59:46 -0000 X-SWARE-Spam-Status: No, hits=-4.8 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,KHOP_RCVD_TRUST,KHOP_THREADED,RCVD_IN_DNSWL_LOW,RCVD_IN_HOSTKARMA_YE X-Spam-Check-By: sourceware.org Received: from mail-wi0-f177.google.com (HELO mail-wi0-f177.google.com) (209.85.212.177) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 12 Oct 2012 05:59:43 +0000 Received: by mail-wi0-f177.google.com with SMTP id hj13so242682wib.12 for ; Thu, 11 Oct 2012 22:59:42 -0700 (PDT) MIME-Version: 1.0 Received: by 10.216.201.198 with SMTP id b48mr1919297weo.126.1350021581898; Thu, 11 Oct 2012 22:59:41 -0700 (PDT) Received: by 10.216.109.201 with HTTP; Thu, 11 Oct 2012 22:59:41 -0700 (PDT) In-Reply-To: <87mwzs8m30.fsf@gmail.com> References: <87y5jfr1ri.fsf@gmail.com> <87mwzs8m30.fsf@gmail.com> Date: Fri, 12 Oct 2012 05:59:00 -0000 Message-ID: Subject: Re: Extending GDB: Python: Wrong handling of 64-bit pointers From: Andrew Pinski To: chandan r Cc: gdb@sourceware.org Content-Type: text/plain; charset=UTF-8 X-IsSubscribed: yes Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2012-10/txt/msg00060.txt.bz2 On Thu, Oct 11, 2012 at 7:23 PM, chandan r wrote: > > Andrew Pinski writes: > >> On Tue, Oct 9, 2012 at 10:30 AM, chandan r wrote: >>> Hi all, >>> >>> As the following CLI interactions show, GDB's python support code seems to be >>> mishandling 64-bit pointers (GNU/Linux on x86-64): >>> >>> NOTE: "p" is a pointer of type "struct task_struct *" >>> >>> (gdb) python print gdb.parse_and_eval("p") >>> 0xffff88001f5f7600 >>> (gdb) python print long(gdb.parse_and_eval("p")) >>> -131940868983296 >>> (gdb) show version >>> show version >>> GNU gdb (GDB) 7.5 >>> Copyright (C) 2012 Free Software Foundation, Inc. >>> License GPLv3+: GNU GPL version 3 or later >>> This is free software: you are free to change and redistribute it. >>> There is NO WARRANTY, to the extent permitted by law. Type "show copying" >>> and "show warranty" for details. >>> This GDB was configured as "x86_64-unknown-linux-gnu". >>> For bug reporting instructions, please see: >>> . >>> >>> Is it GDB or am I messing up something here? >> >> Nothing looks wrong as -131940868983296 is the same as >> 0xffff88001f5f7600 in signed integer. >> (gdb) p/x -131940868983296 >> $1 = 0xffff88001f5f7600 >> >> Thanks, >> Andrew Pinski >> >>> >>> -- >>> Chandan > > But shouldn't pointer values be read/printed without interpretting the sign > bit?. > > Right now I have to do 'long(str(gdb.parse_and_eval('p')), 16)' to obtain the > correct value. What is the correct value for pointers cast to an long? I don't see the issue here as you have a pointer which is 64bits and you cast directly to a signed long. Thanks, Andrew Pinski > > -- > chandan