Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752117AbbBVSs4 (ORCPT ); Sun, 22 Feb 2015 13:48:56 -0500 Received: from relay4-d.mail.gandi.net ([217.70.183.196]:38838 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751810AbbBVSsz (ORCPT ); Sun, 22 Feb 2015 13:48:55 -0500 X-Originating-IP: 50.43.43.179 Date: Sun, 22 Feb 2015 10:48:45 -0800 From: Josh Triplett To: Arjan van de Ven Cc: paulmck@linux.vnet.ibm.com, Peter Zijlstra , linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods Message-ID: <20150222184844.GA4262@thin> References: <20150220050850.GA32639@linux.vnet.ibm.com> <20150220091107.GN21418@twins.programming.kicks-ass.net> <20150220163737.GL5745@linux.vnet.ibm.com> <20150220165409.GU5029@twins.programming.kicks-ass.net> <20150220171442.GM5745@linux.vnet.ibm.com> <54E76FB7.4060005@linux.intel.com> <20150220182745.GN5745@linux.vnet.ibm.com> <54E8A986.4090302@linux.intel.com> <20150222035806.GA4452@thin> <54EA207E.3090502@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54EA207E.3090502@linux.intel.com> 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 Content-Length: 961 Lines: 20 On Sun, Feb 22, 2015 at 10:31:26AM -0800, Arjan van de Ven wrote: > >>To show the boot time, I'm using the timestamp of the "Write protecting" line, > >>that's pretty much the last thing we print prior to ring 3 execution. > > > >That's a little sad; we ought to be write-protecting kernel read-only > >data as *early* as possible. > > well... if you are compromised before the first ring 3 instruction... > .... you have a slightly bigger problem than where in the kernel we write protect things. Definitely not talking about malicious compromise here; malicious code could just remove the write protection. However, write-protecting kernel read-only data also protects against a class of bugs. - Josh Triplett -- 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/