From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 28462 invoked by alias); 10 Jun 2007 06:24:19 -0000 Received: (qmail 28455 invoked by uid 22791); 10 Jun 2007 06:24:19 -0000 X-Spam-Status: No, hits=0.6 required=5.0 tests=BAYES_50,DK_POLICY_SIGNSOME,SARE_MSGID_LONG40 X-Spam-Check-By: sourceware.org Received: from py-out-1112.google.com (HELO py-out-1112.google.com) (64.233.166.183) by sourceware.org (qpsmtpd/0.31) with ESMTP; Sun, 10 Jun 2007 06:24:17 +0000 Received: by py-out-1112.google.com with SMTP id d32so2188765pye for ; Sat, 09 Jun 2007 23:24:15 -0700 (PDT) Received: by 10.114.204.13 with SMTP id b13mr4273098wag.1181456655146; Sat, 09 Jun 2007 23:24:15 -0700 (PDT) Received: by 10.114.196.9 with HTTP; Sat, 9 Jun 2007 23:24:15 -0700 (PDT) Message-ID: <5640c7e00706092324kd0ea8e0pef4a4cd764fce5d3@mail.gmail.com> Date: Sun, 10 Jun 2007 06:24:00 -0000 From: "Ian McDonald" To: prasanna@in.ibm.com Subject: Re: [PATCH] Kprobes i386 fix for mark ro data Cc: "Andrew Morton" , "Andi Kleen" , "Jim Keniston" , "Chuck Ebbert" , "Linux Kernel Mailing List" , ananth@in.ibm.com, anil.s.keshavamurthy@intel.com, "David S. Miller" , "Patrick Andrieux" , "DCCP Mailing List" , jbeulich@novell.com, systemtap@sources.redhat.com In-Reply-To: <20070607042229.GA9350@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <5640c7e00706061347v42c9ecbahb5354f6687a70a78@mail.gmail.com> <46673B76.2090508@redhat.com> <5640c7e00706061612h62074699wdbd2725654a164@mail.gmail.com> <20070607042229.GA9350@in.ibm.com> Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2007-q2/txt/msg00550.txt.bz2 On 6/7/07, S. P. Prasanna wrote: > > >It faulted when it tried to write the breakpoint instruction into the > > >running kernel's executable code. Apparently the kernel code is now marked > > >read-only? > > > > > > > > Yes it would appear to be the case as user has CONFIG_DEBUG_RODATA > > set. Patrick - can you turn this off and retest? It's under Kernel > > Hacking, Write protect kernel read only data structures. > > > > Ian, > > Please find the fix as suggested by Andi Kleen > for the above stated problem. > > Thanks > Prasanna > > I went to test the fix and first of all went to replicate the problem. My build has CONFIG_DEBUG_RODATA set but the problem does not occur without the patch. Should I be concerned about this and raise a bug for that as I would think that means there is a problem that the read only protection isn't working (this is off Linus' tree synced tonight). Patrick - can you test whether this patch fixes your problem? You said disabling CONFIG_DEBUG_RODATA fixed your problem but can you try re-enabling and testing this patch? Ian -- Web: http://wand.net.nz/~iam4/ Blog: http://iansblog.jandi.co.nz WAND Network Research Group