From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9395 invoked by alias); 3 Apr 2012 14:18:07 -0000 Received: (qmail 9387 invoked by uid 22791); 3 Apr 2012 14:18:06 -0000 X-SWARE-Spam-Status: No, hits=-7.0 required=5.0 tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,KHOP_THREADED,RCVD_IN_DNSWL_HI,RCVD_IN_HOSTKARMA_W,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 03 Apr 2012 14:17:48 +0000 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q33EHlC9032395 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 3 Apr 2012 10:17:47 -0400 Received: from [10.11.8.108] (vpn-8-108.rdu.redhat.com [10.11.8.108]) by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q33EHktZ019915; Tue, 3 Apr 2012 10:17:47 -0400 Message-ID: <4F7B068A.9090708@redhat.com> Date: Tue, 03 Apr 2012 14:18:00 -0000 From: William Cohen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.3) Gecko/20120307 Thunderbird/10.0.3 MIME-Version: 1.0 To: David Smith CC: systemtap@sourceware.org Subject: Re: Improve build-id checking when the task we're interested in isn't 'current'. git commit causing problems on ARM and IA64 References: <4F76225B.8010600@redhat.com> <4F79FE43.9010902@redhat.com> <4F7A091E.6040208@redhat.com> <4F7A23DB.5000800@redhat.com> In-Reply-To: <4F7A23DB.5000800@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes 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: 2012-q2/txt/msg00010.txt.bz2 On 04/02/2012 06:10 PM, David Smith wrote: > On 04/02/2012 03:16 PM, William Cohen wrote: > >> On 04/02/2012 03:30 PM, David Smith wrote: >>> ../install/bin/stap -k ../systemtap/testsuite/systemtap.base/add.stp >> >> Hi David, >> >> Thanks for taking a look at this problem. >> >> The git checkin fixes the problem for ia64. >> >> The arm machine is using a kernel from the linus torvald's git repo. This particular kernel doesn't > >> have utrace support in it, so it doesn't have CONFIG_UTRACE set. >> Thus, things still fail in the same way on the ARM machine. > >> >> Does this code work with stock x86_64 kernel? I am wondering why this problem wasn't seen on the x86 > >> machine. Does the x86 not need to do the explicit flushes unlike the >> ia64 and ARM? > > Right. From what I've been looking at on the stock x86_64 kernel, > copy_to_user_page() boils down to a memcpy() call. > > Since x86_64 doesn't have an arch-specific cacheflush.h file, it > inherits the following from asm-generic/cacheflush.h: > > ==== > .... > #define flush_icache_user_range(vma,pg,adr,len) do { } while (0) > .... > #define copy_to_user_page(vma, page, vaddr, dst, src, len) \ > do { \ > memcpy(dst, src, len); \ > flush_icache_user_range(vma, page, vaddr, len); \ > } while (0) > ==== > > Arm has a arch-specific copy_to_user_page() (defined in > arch/arm/include/cacheflush.h) which isn't exported. Sigh. > > It looks like on current kernels access_process_vm() is exported, which > means we could use the real function instead of our copy (can you check > and make sure this is exported on arm?). However, we've added the > __access_process_vm_noflush() variant which isn't present upstream. > > I'm not sure there are easy answers here. > I looked through Module.symvers for the currently running kernel on the ARM machine and didn't see access_process_vm listed. Also seems that all the uses of access_process_vm() were for things that are built into the kernel rather than modules. -Will