From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751351AbeBTIcY (ORCPT ); Tue, 20 Feb 2018 03:32:24 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:55377 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751043AbeBTIcX (ORCPT ); Tue, 20 Feb 2018 03:32:23 -0500 X-Google-Smtp-Source: AH8x226GleKCmS5bnriUaYwLjtPk21EfcASdY5LDlF+LXYV49uWbJVcd4y2FQUGvUGNeEihRFDpXyg== Date: Tue, 20 Feb 2018 09:32:11 +0100 From: Ingo Molnar To: Jan Beulich Cc: mingo@elte.hu, tglx@linutronix.de, Boris Ostrovsky , Juergen Gross , linux-kernel@vger.kernel.org, hpa@zytor.com Subject: Re: [PATCH RESEND] x86: consider effective protection attributes in W+X check Message-ID: <20180220083211.s5wr5r7ocpzzizgp@gmail.com> References: <5A8BDF3602000078001A96CD@prv-mh.provo.novell.com> <20180220081042.wgriecqneizg3df7@gmail.com> <5A8BE8C602000078001A9729@prv-mh.provo.novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5A8BE8C602000078001A9729@prv-mh.provo.novell.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jan Beulich wrote: > >>> On 20.02.18 at 09:10, wrote: > > * Jan Beulich wrote: > >> Using just the leaf page table entry flags would cause a false warning > >> in case _PAGE_RW is clear or _PAGE_NX is set in a higher level entry. > > > > Under what circumstances did you see false positive warnings? > > As explained in the 2-patch series this was originally part of, there > continues to be that W+X warning when running under Xen, as > commit 2cc42bac1c ("x86-64/Xen: eliminate W+X mappings") has > to make the necessary adjustment in L2 rather than L1 (the > reason is explained there). I.e. _PAGE_RW is clear there in L1, > but _PAGE_NX is set in L2. This would make an excellent additional paragraph of the v2 changelog. Thanks, Ingo