Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752334Ab3G2JHB (ORCPT ); Mon, 29 Jul 2013 05:07:01 -0400 Received: from cantor2.suse.de ([195.135.220.15]:56141 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751652Ab3G2JG7 (ORCPT ); Mon, 29 Jul 2013 05:06:59 -0400 Date: Mon, 29 Jul 2013 11:06:53 +0200 (CEST) From: Jiri Kosina To: "H. Peter Anvin" Cc: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, masami.hiramatsu.pt@hitachi.com, rostedt@goodmis.org, tglx@linutronix.de, fengguang.wu@intel.com, tip-bot for Jiri Kosina , linux-tip-commits@vger.kernel.org Subject: Re: [tip:perf/core] kprobes/x86: Call out into INT3 handler directly instead of using notifier In-Reply-To: <51EFE5A8.1060109@linux.intel.com> Message-ID: References: <51EFE5A8.1060109@linux.intel.com> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1418 Lines: 35 On Wed, 24 Jul 2013, H. Peter Anvin wrote: > > Commit-ID: 17f41571bb2c4a398785452ac2718a6c5d77180e > > Gitweb: http://git.kernel.org/tip/17f41571bb2c4a398785452ac2718a6c5d77180e > > Author: Jiri Kosina > > AuthorDate: Tue, 23 Jul 2013 10:09:28 +0200 > > Committer: Ingo Molnar > > CommitDate: Tue, 23 Jul 2013 10:12:57 +0200 > > > > kprobes/x86: Call out into INT3 handler directly instead of using notifier > > > > In fd4363fff3d96 ("x86: Introduce int3 (breakpoint)-based > > instruction patching"), the mechanism that was introduced for > > notifying alternatives code from int3 exception handler that and > > exception occured was die_notifier. > > > > This is however problematic, as early code might be using jump > > labels even before the notifier registration has been performed, > > which will then lead to an oops due to unhandled exception. One > > of such occurences has been encountered by Fengguang: > > > > Please note that putting this patch in perf/core means x86/jumplabel is > completely nonfunctional by itself. I'd like to point out that this is still the case ... TIA, -- Jiri Kosina SUSE Labs -- 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/