Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752552AbeAETRW (ORCPT + 1 other); Fri, 5 Jan 2018 14:17:22 -0500 Received: from mx2.suse.de ([195.135.220.15]:47828 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752166AbeAETRV (ORCPT ); Fri, 5 Jan 2018 14:17:21 -0500 Date: Fri, 5 Jan 2018 20:17:17 +0100 (CET) From: Jiri Kosina To: Dave Hansen cc: Yisheng Xie , linux-kernel@vger.kernel.org, linux-mm@kvack.org, richard.fellner@student.tugraz.at, moritz.lipp@iaik.tugraz.at, daniel.gruss@iaik.tugraz.at, michael.schwarz@iaik.tugraz.at, luto@kernel.org, Linus Torvalds , keescook@google.com, hughd@google.com, x86@kernel.org, Andrea Arcangeli Subject: Re: [PATCH 05/23] x86, kaiser: unmap kernel from userspace page tables (core patch) In-Reply-To: <282e2a56-ded1-6eb9-5ecb-22858c424bd7@linux.intel.com> Message-ID: References: <20171123003438.48A0EEDE@viggo.jf.intel.com> <20171123003447.1DB395E3@viggo.jf.intel.com> <93776eb2-b6d4-679a-280c-8ba558a69c34@linux.intel.com> <20a54a5f-f4e5-2126-fb73-6a995d13d52d@linux.intel.com> <282e2a56-ded1-6eb9-5ecb-22858c424bd7@linux.intel.com> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) 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 Return-Path: On Fri, 5 Jan 2018, Dave Hansen wrote: > > --- a/arch/x86/platform/efi/efi_64.c > > +++ b/arch/x86/platform/efi/efi_64.c > > @@ -95,6 +95,12 @@ pgd_t * __init efi_call_phys_prolog(void > > save_pgd[pgd] = *pgd_offset_k(pgd * PGDIR_SIZE); > > vaddress = (unsigned long)__va(pgd * PGDIR_SIZE); > > set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress)); > > + /* > > + * pgprot API doesn't clear it for PGD > > + * > > + * Will be brought back automatically in _epilog() > > + */ > > + pgd_offset_k(pgd * PGDIR_SIZE)->pgd &= ~_PAGE_NX; > > } > > __flush_tlb_all(); > > Wait a sec... Where does the _PAGE_USER come from? Shouldn't we see > the &init_mm in there and *not* set _PAGE_USER? That's because pgd_populate() uses _PAGE_TABLE and not _KERNPG_TABLE for reasons that are behind me. I did put this on my TODO list, but for later. (and yes, I tried clearing _PAGE_USER from init_mm's PGD, and no obvious breakages appeared, but I wanted to give it more thought later). -- Jiri Kosina SUSE Labs