Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754012AbdLNWYQ (ORCPT ); Thu, 14 Dec 2017 17:24:16 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:38484 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753272AbdLNWYN (ORCPT ); Thu, 14 Dec 2017 17:24:13 -0500 Date: Thu, 14 Dec 2017 23:23:55 +0100 (CET) From: Thomas Gleixner To: Linus Torvalds cc: Andy Lutomirski , Peter Zijlstra , "linux-kernel@vger.kernel.org" , X86 ML , Dave Hansen , Borislav Petkov , Greg KH , Kees Cook , Hugh Dickins , Brian Gerst , Josh Poimboeuf , Denys Vlasenko , Boris Ostrovsky , Juergen Gross , David Laight , Eduardo Valentin , "Liguori, Anthony" , Will Deacon , "linux-mm@kvack.org" , "Kirill A. Shutemov" , Dan Williams Subject: Re: [PATCH v2 11/17] selftests/x86/ldt_gdt: Prepare for access bit forced In-Reply-To: Message-ID: References: <20171214112726.742649793@infradead.org> <20171214113851.647809433@infradead.org> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 660 Lines: 23 On Thu, 14 Dec 2017, Linus Torvalds wrote: > On Thu, Dec 14, 2017 at 1:22 PM, Andy Lutomirski wrote: > > > > Which kind of kills the whole thing. There's no way the idea of > > putting the LDT in a VMA is okay if it's RW. > > Sure there is. > > I really don't understand why you guys think it has to be RO. > > All it has to be is not _user_ accessible. And that's a requirement > regardless, because no way in hell should users be able to read the > damn thing. The user knows the LDT contents because he put it there and it can be read via modify_ldt(0, ) anyway. Or am I misunderstanding what you are trying to say? Thanks, tglx