From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 9B3EA6B0253 for ; Thu, 2 Nov 2017 03:07:49 -0400 (EDT) Received: by mail-pg0-f70.google.com with SMTP id s75so5018342pgs.12 for ; Thu, 02 Nov 2017 00:07:49 -0700 (PDT) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id o11si1385710pll.537.2017.11.02.00.07.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 02 Nov 2017 00:07:48 -0700 (PDT) Received: from mail-io0-f181.google.com (mail-io0-f181.google.com [209.85.223.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 171732193B for ; Thu, 2 Nov 2017 07:07:48 +0000 (UTC) Received: by mail-io0-f181.google.com with SMTP id p186so11586069ioe.12 for ; Thu, 02 Nov 2017 00:07:48 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <20171031223146.6B47C861@viggo.jf.intel.com> <20171031223150.AB41C68F@viggo.jf.intel.com> From: Andy Lutomirski Date: Thu, 2 Nov 2017 00:07:26 -0700 Message-ID: Subject: Re: [PATCH 02/23] x86, kaiser: do not set _PAGE_USER for init_mm page tables Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner Cc: Andy Lutomirski , Dave Hansen , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , moritz.lipp@iaik.tugraz.at, Daniel Gruss , michael.schwarz@iaik.tugraz.at, Linus Torvalds , Kees Cook , Hugh Dickins , X86 ML On Wed, Nov 1, 2017 at 2:28 PM, Thomas Gleixner wrote: > On Wed, 1 Nov 2017, Andy Lutomirski wrote: > >> On Wed, Nov 1, 2017 at 2:11 PM, Thomas Gleixner wrote: >> > On Tue, 31 Oct 2017, Dave Hansen wrote: >> > >> >> >> >> init_mm is for kernel-exclusive use. If someone is allocating page >> >> tables in it, do not set _PAGE_USER on them. This ensures that >> >> we do *not* set NX on these page tables in the KAISER code. >> > >> > This changelog is confusing at best. >> > >> > Why is this a kaiser issue? Nothing should ever create _PAGE_USER entries >> > in init_mm, right? >> >> The vsyscall page is _PAGE_USER and lives in init_mm via the fixmap. > > Groan, forgot about that abomination, but still there is no point in having > it marked PAGE_USER in the init_mm at all, kaiser or not. > How can it be PAGE_USER in user mms but not init_mm? It's the same page table. > Thanks, > > tglx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org