Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752808Ab3J3VLO (ORCPT ); Wed, 30 Oct 2013 17:11:14 -0400 Received: from mail-pd0-f174.google.com ([209.85.192.174]:33119 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752640Ab3J3VLL (ORCPT ); Wed, 30 Oct 2013 17:11:11 -0400 Message-ID: <527175EB.9000809@linaro.org> Date: Wed, 30 Oct 2013 17:11:07 -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 02/13] uprobes: allow ignoring of probe hits References: <1381871068-27660-1-git-send-email-dave.long@linaro.org> <1381871068-27660-3-git-send-email-dave.long@linaro.org> <20131019170214.GA8324@redhat.com> <20131028185425.GA12863@redhat.com> In-Reply-To: <20131028185425.GA12863@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: 1358 Lines: 47 Sorry for the delay, all this week it's me that's traveling. On 10/28/13 14:54, Oleg Nesterov wrote: > David, sorry for delay. > > On 10/19, Oleg Nesterov wrote: >> >> On 10/15, David Long wrote: >>> >>> @@ -1732,9 +1732,6 @@ static void handle_swbp(struct pt_regs *regs) >>> return; >>> } >>> >>> - /* change it in advance for ->handler() and restart */ >>> - instruction_pointer_set(regs, bp_vaddr); >>> - >> >> Well, this looks obviously wrong. This SET_IP() has the comment ;) >> >> Note also that with this breaks __skip_sstep() on x86. > > Hmm. Thinking more, it seems that this patch has another problem. > > IIUC, the whole point of arch_uprobe_ignore() is to avoid > handler_chain() if the condition was not satisfied, so you need > to call it before handler_chain() ? Yes, you're right. I can see now that is a bad merge of an earlier version of the patch. I have just tested the fix. Thanks for finding this. > > Otherwise this logic should go into can_skip_sstep() and we simply > do not need the new hook, just we need to tweak the (ugly) > UPROBE_SKIP_SSTEP logic. > > Oleg. > -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/