Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753716AbbGXPuV (ORCPT ); Fri, 24 Jul 2015 11:50:21 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:9467 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752047AbbGXPuT (ORCPT ); Fri, 24 Jul 2015 11:50:19 -0400 Date: Fri, 24 Jul 2015 17:49:26 +0200 From: Willy Tarreau To: Steven Rostedt Cc: Peter Zijlstra , Linus Torvalds , Andy Lutomirski , X86 ML , "linux-kernel@vger.kernel.org" , Borislav Petkov , Thomas Gleixner , Brian Gerst Subject: Re: Dealing with the NMI mess Message-ID: <20150724154926.GE3612@1wt.eu> References: <20150724081326.GO25159@twins.programming.kicks-ass.net> <20150724075841.40f209f4@gandalf.local.home> <20150724124304.GH19282@twins.programming.kicks-ass.net> <20150724090342.6d11e16d@gandalf.local.home> <20150724132128.GA3612@1wt.eu> <20150724103127.3c3f4693@gandalf.local.home> <20150724145901.GB3612@1wt.eu> <20150724111621.34713023@gandalf.local.home> <20150724152637.GC3612@1wt.eu> <20150724113426.3b0d3706@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150724113426.3b0d3706@gandalf.local.home> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1053 Lines: 30 On Fri, Jul 24, 2015 at 11:34:26AM -0400, Steven Rostedt wrote: > On Fri, 24 Jul 2015 17:26:37 +0200 > Willy Tarreau wrote: > > > > > The point is, if we trigger a #DB on an instruction breakpoint > > > while !IF, then we simply disable that breakpoint and do the RET. > > > > Yes but the breakpoint remains disabled then. Or I'm missing > > something. > > Do we care? If it was an instruction breakpoint with !IF set, then it > had to have happened in the kernel. And kgdb or whatever added it there > needs to deal with that. I was concerned that an RW BP would remain disabled when returning to user space but Peter cleared that out by pointing me to the discussion where it was explained that they are re-enabled when returning to user space. So no problem here for me. Thanks, Willy -- 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/