Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754071Ab1D0GI1 (ORCPT ); Wed, 27 Apr 2011 02:08:27 -0400 Received: from ozlabs.org ([203.10.76.45]:58947 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753799Ab1D0GHP (ORCPT ); Wed, 27 Apr 2011 02:07:15 -0400 From: Rusty Russell To: Jan Glauber Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, castet.matthieu@free.fr, sliakh.lkml@gmail.com, jiang@cs.ncsu.edu, mingo@elte.hu Subject: Re: Undoing module RONX protection fix In-Reply-To: <20110421141949.GA10675@hal> References: <20110418092348.GB7786@hal> <20110418092801.GC3837@infradead.org> <874o5v6drb.fsf@rustcorp.com.au> <20110421141949.GA10675@hal> User-Agent: Notmuch/0.3.1 (http://notmuchmail.org) Emacs/23.1.1 (i686-pc-linux-gnu) Date: Wed, 27 Apr 2011 14:42:34 +0930 Message-ID: <87ipu0l1kt.fsf@rustcorp.com.au> 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: 2088 Lines: 45 On Thu, 21 Apr 2011 16:19:49 +0200, Jan Glauber wrote: > On Mon, Apr 18, 2011 at 08:13:36PM +0930, Rusty Russell wrote: > > On Mon, 18 Apr 2011 11:23:48 +0200, Jan Glauber wrote: > > > While debugging I stumbled over two problems in the code that protects module > > > pages. > > > > > > First issue is that disabling the protection before freeing init or unload of > > > a module is not symmetric with the enablement. For instance, if pages are set > > > to RO the page range from module_core to module_core + core_ro_size is > > > protected. If a module is unloaded the page range from module_core to > > > module_core + core_size is set back to RW. > > > So pages that were not set to RO are also changed to RW. > > > This is not critical but IMHO it should be symmetric. > > > > > > Second issue is that while set_memory_rw & set_memory_ro are used for > > > RO/RW changes only set_memory_nx is involved for NX/X. One would await that > > > the inverse function is called when the NX protection should be removed, > > > which is not the case here, unless I'm missing something. > > > > > > The following patch addresses both issues. Works on s390. Boot tested on x86. > > > > > > Please comment, > > > > Applied, minus the S/390 EXPORT_SYMBOL which Christoph pointed out. I > > turned your mail into the commit message, since it was clearer and more > > verbose. I don't see why they would be different. > > There's a bug in my patch which just killed one of my s390 machines. > Can you merge this with the previuos patch? Hmm... Applied, but that function is really kind of silly. We should probably just split into unset_section_ro_nx() into unset_module_init_ro_nx() and unset_module_core_ro_nx(). (And why isn't that function static anyway?) Patch appreciated :) Rusty. -- 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/