From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19827 invoked by alias); 23 Jul 2007 16:06:28 -0000 Received: (qmail 19818 invoked by uid 22791); 23 Jul 2007 16:06:27 -0000 X-Spam-Check-By: sourceware.org Received: from venus.billgatliff.com (HELO venus.billgatliff.com) (209.251.101.201) by sourceware.org (qpsmtpd/0.31) with ESMTP; Mon, 23 Jul 2007 16:06:20 +0000 Received: from [192.168.2.10] (adsl-75-23-81-9.dsl.peoril.sbcglobal.net [75.23.81.9]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by venus.billgatliff.com (Postfix) with ESMTP id 97D69A418B; Mon, 23 Jul 2007 11:06:17 -0500 (CDT) Message-ID: <46A4D1F5.1060005@billgatliff.com> Date: Mon, 23 Jul 2007 16:15:00 -0000 From: Bill Gatliff User-Agent: Icedove 1.5.0.10 (X11/20070329) MIME-Version: 1.0 To: Bill Gatliff , gdb@sourceware.org, linuxppc-embedded@ozlabs.org Subject: Re: Gdbserver syscall clobber References: <469B922D.3050701@billgatliff.com> <20070716155348.GA5281@caradoc.them.org> <469E550E.5080905@billgatliff.com> <20070718183143.GA25324@caradoc.them.org> In-Reply-To: <20070718183143.GA25324@caradoc.them.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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: 2007-07/txt/msg00160.txt.bz2 Daniel Jacobowitz wrote: > On Wed, Jul 18, 2007 at 12:59:42PM -0500, Bill Gatliff wrote: > >> Now, I'm a little rusty on PPC asm (I've been doing a lot of ARM >> lately), but it looks to me like the kernel is setting bit 0 in CR0 >> (oris r10, r10, 0x1000) a.k.a LT, but the user side is looking at CR0 >> (bnslr+) bit 3 a.k.a. SO. Or maybe the other way around, I'm not sure >> after reading Sections 1.2 and 2.1 of the Programming Environments manual. >> > > It's not checking for restart here - userspace isn't supposed to have to. > It's probably checking for error. Check for the bit of kernel code > that's supposed to back you up two instructions. > > I don't see it in this kernel. What I see is this after the call to the syscall handler: li r10,-_LAST_ERRNO cmpl 0,r3,r10 blt 30f neg r3,r3 cmpi 0,r3,ERESTARTNOHAND bne 22f li r3,EINTR 22: lwz r10,_CCR(r1) /* Set SO bit in CR */ oris r10,r10,0x1000 stw r10,_CCR(r1) 30: stw r3,GPR3(r1) /* Update return value */ b ret_from_except 66: li r3,ENOSYS b 22b ? -- Bill Gatliff bgat@billgatliff.com