From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17800 invoked by alias); 12 Dec 2013 10:31:57 -0000 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 Received: (qmail 17788 invoked by uid 89); 12 Dec 2013 10:31:56 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.6 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail9.hitachi.co.jp Received: from mail9.hitachi.co.jp (HELO mail9.hitachi.co.jp) (133.145.228.44) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 12 Dec 2013 10:31:55 +0000 Received: from mlsv7.hitachi.co.jp (unknown [133.144.234.166]) by mail9.hitachi.co.jp (Postfix) with ESMTP id 4EA0D37C85; Thu, 12 Dec 2013 19:31:53 +0900 (JST) Received: from mfilter03.hitachi.co.jp by mlsv7.hitachi.co.jp (8.13.1/8.13.1) id rBCAVrrO022211; Thu, 12 Dec 2013 19:31:53 +0900 Received: from vshuts01.hitachi.co.jp (vshuts01.hitachi.co.jp [10.201.6.83]) by mfilter03.hitachi.co.jp (Switch-3.3.4/Switch-3.3.4) with ESMTP id rBCAVpFh014240; Thu, 12 Dec 2013 19:31:52 +0900 Received: from gxml20a.ad.clb.hitachi.co.jp (unknown [158.213.157.160]) by vshuts01.hitachi.co.jp (Postfix) with ESMTP id 199202F003A; Thu, 12 Dec 2013 19:31:51 +0900 (JST) Received: from [10.198.211.167] by gxml20a.ad.clb.hitachi.co.jp (Switch-3.1.10/Switch-3.1.9) id 5BCA1VEZS00007630; Thu, 12 Dec 2013 19:31:50 +0900 Message-ID: <52A99092.6080305@hitachi.com> Date: Thu, 12 Dec 2013 10:31:00 -0000 From: Masami Hiramatsu User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Jiri Kosina Cc: Steven Rostedt , Ingo Molnar , Andi Kleen , Ananth N Mavinakayanahalli , Sandeepa Prabhu , Frederic Weisbecker , x86@kernel.org, lkml , Andrew Morton , Ingo Molnar , systemtap@sourceware.org, "H. Peter Anvin" , Sasha Levin , Thomas Gleixner , Seiji Aguchi , "David S. Miller" Subject: Re: [PATCH -tip v4 6/6] [RFC] kprobes/x86: Call exception handlers directly from do_int3/do_debug References: <20131204012841.22118.82992.stgit@kbuild-fedora.novalocal> <20131204012856.22118.91079.stgit@kbuild-fedora.novalocal> <20131203213904.5ff1794c@gandalf.local.home> <52A93E3A.9080600@hitachi.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2013-q4/txt/msg00401.txt.bz2 (2013/12/12 18:59), Jiri Kosina wrote: > On Thu, 12 Dec 2013, Masami Hiramatsu wrote: > >>> Yeah, it's broken. Obviously, if you happen to trigger int3 before the >>> notifier has been registered, it'd cause int3 exception to be unhandled. >>> See >>> >>> commit 17f41571bb2c4a398785452ac2718a6c5d77180e >>> Author: Jiri Kosina >>> Date: Tue Jul 23 10:09:28 2013 +0200 >>> >>> kprobes/x86: Call out into INT3 handler directly instead of using notifier >>> >>> for one such issue that happened with jump labels. >>> >>>> Hmm, if there's no users of the int3 notifier, should we just remove it? >>> >>> Hmm, there are still uprobes, right? >> >> Right, uprobes still use it, however, since it only handles user-space >> breakpoint, there is no problem. > > Agreed. But therefore the notifier can't just be removed, unless uprobes > are converted to direct call as well (but I don't think that'd be > beneficial, notifier is sufficient in this case). Ah, I don't intended to remove notify_die from do_int3, since notify_die notifies many other exceptions too. :) Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com