Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752640Ab3JWSU6 (ORCPT ); Wed, 23 Oct 2013 14:20:58 -0400 Received: from mail-yh0-f49.google.com ([209.85.213.49]:57264 "EHLO mail-yh0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751480Ab3JWSU5 (ORCPT ); Wed, 23 Oct 2013 14:20:57 -0400 Message-ID: <5268137F.3030809@linaro.org> Date: Wed, 23 Oct 2013 14:20:47 -0400 From: David Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: Oleg Nesterov CC: linux-arm-kernel@lists.infradead.org, Rabin Vincent , "Jon Medhurst (Tixy)" , Srikar Dronamraju , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 05/13] uprobes: add arch write opcode hook References: <1381871068-27660-1-git-send-email-dave.long@linaro.org> <1381871068-27660-6-git-send-email-dave.long@linaro.org> <20131019165051.GC7837@redhat.com> In-Reply-To: <20131019165051.GC7837@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1505 Lines: 43 On 10/19/13 12:50, Oleg Nesterov wrote: > On 10/15, David Long wrote: >> >> Allow arches to write the opcode with a custom function. ARM needs to >> customize the swbp instruction depending on the condition code of the >> instruction it replaces. > > Well, we already have "__weak set_swbp(auprobe, ...)", can't arm use it? > > If not, > >> +void __weak arch_uprobe_write_opcode(struct arch_uprobe *auprobe, void *vaddr, >> + uprobe_opcode_t opcode) >> +{ >> + memcpy(vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); >> +} >> ... >> - copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); >> + vaddr_new = kmap_atomic(new_page); >> + arch_uprobe_write_opcode(auprobe, vaddr_new + (vaddr & ~PAGE_MASK), >> + opcode); >> + kunmap_atomic(vaddr_new); > > Again, if you need to add the new __weak helper, I think it should simply > do copy_to_page(). > > Oleg. > Unfortunately, providing an alternative set_swbp() would mean duplicating a moderate chunk of code from kernel/uprobes.c. Adding arch_uprobe_write_opcode() feels a little more like the right thing to do to me. I notice there don't seem to be any alternative set_swbp functions in the (rc6) kernel tree. I will adjust the arch_uprobe_write_opcode imlementation as suggested. -dl -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/