From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752692AbbLNIJU (ORCPT ); Mon, 14 Dec 2015 03:09:20 -0500 Received: from mail-wm0-f48.google.com ([74.125.82.48]:35689 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751045AbbLNIJT (ORCPT ); Mon, 14 Dec 2015 03:09:19 -0500 Date: Mon, 14 Dec 2015 09:09:14 +0100 From: Ingo Molnar To: Jeff Merkey Cc: Andy Lutomirski , Thomas Gleixner , LKML , Ingo Molnar , "H. Peter Anvin" , X86 ML , Peter Zijlstra , Andy Lutomirski , Masami Hiramatsu , Steven Rostedt , Borislav Petkov , Jiri Olsa Subject: Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Message-ID: <20151214080914.GA20556@gmail.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? * Jeff Merkey wrote: > I trigger it by writing to the dr7 and dr1, 2, 3 or four register and > set an execute breakpoint without going through > arch_install_hw_breakpoint. When the breakpoint fires, the system > crashes and hangs on the processor stuck in an endless loop inside the > int1 handler in hw_breakpoint.c -- What is still not clear to me, can you trigger the hang not via some special kernel driver that goes outside regular APIs and messes with the state of the debug registers, but via the proper access methods, i.e. various user-space ABIs? Thanks, Ingo