From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94FA8C433DF for ; Tue, 16 Jun 2020 14:39:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 714CE20644 for ; Tue, 16 Jun 2020 14:39:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726817AbgFPOjq (ORCPT ); Tue, 16 Jun 2020 10:39:46 -0400 Received: from verein.lst.de ([213.95.11.211]:38516 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726341AbgFPOjp (ORCPT ); Tue, 16 Jun 2020 10:39:45 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 08C8368AEF; Tue, 16 Jun 2020 16:39:41 +0200 (CEST) Date: Tue, 16 Jun 2020 16:39:40 +0200 From: Christoph Hellwig To: Peter Zijlstra Cc: Christoph Hellwig , Dexuan Cui , vkuznets , Stephen Hemminger , Andy Lutomirski , Andy Lutomirski , Michael Kelley , Ju-Hyoung Lee , "x86@kernel.org" , "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" , KY Srinivasan , Tom Lendacky Subject: Re: hv_hypercall_pg page permissios Message-ID: <20200616143940.GA15676@lst.de> References: <20200616072318.GA17600@lst.de> <20200616101807.GO2531@hirez.programming.kicks-ass.net> <20200616102350.GA29684@lst.de> <20200616102412.GB29684@lst.de> <20200616103137.GQ2531@hirez.programming.kicks-ass.net> <20200616103313.GA30833@lst.de> <20200616104032.GR2531@hirez.programming.kicks-ass.net> <20200616104230.GA31314@lst.de> <20200616105200.GA32175@lst.de> <20200616112415.GT2531@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200616112415.GT2531@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-hyperv-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Tue, Jun 16, 2020 at 01:24:15PM +0200, Peter Zijlstra wrote: > > +void *module_alloc_prot(unsigned long size, pgprot_t prot) > > { > > + unsigned int flags = (pgprot_val(prot) & _PAGE_NX) ? > > + 0 : VM_FLUSH_RESET_PERMS; > > void *p; > > > > if (PAGE_ALIGN(size) > MODULES_LEN) > > @@ -75,7 +77,7 @@ void *module_alloc(unsigned long size) > > p = __vmalloc_node_range(size, MODULE_ALIGN, > > MODULES_VADDR + get_module_load_offset(), > > MODULES_END, GFP_KERNEL, > > - PAGE_KERNEL, 0, NUMA_NO_NODE, > > + prot, flags, NUMA_NO_NODE, > > __builtin_return_address(0)); > > if (p && (kasan_module_alloc(p, size) < 0)) { > > vfree(p); > > Hurmm.. Yes it would. It just doesn't feel right though. Can't we > unconditionally set the flag? At worst it makes free a little bit more > expensive. > > The thing is, I don't think _NX is the only prot that needs restoring. > Any prot other than the default (RW IIRC) needs restoring. If that actually is the case I think we should just check for a non-default permission in __vmalloc_node_range itself and handle it there, which seems like a nice solution.