From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752183AbdLDRBI (ORCPT ); Mon, 4 Dec 2017 12:01:08 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:60328 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752489AbdLDQve (ORCPT ); Mon, 4 Dec 2017 11:51:34 -0500 Message-Id: <20171204150608.198490331@linutronix.de> User-Agent: quilt/0.63-1 Date: Mon, 04 Dec 2017 15:07:47 +0100 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Linus Torvalds , Andy Lutomirsky , Peter Zijlstra , Dave Hansen , Borislav Petkov , Greg KH , keescook@google.com, hughd@google.com, Brian Gerst , Josh Poimboeuf , Denys Vlasenko , Rik van Riel , Boris Ostrovsky , Juergen Gross , David Laight , Eduardo Valentin , aliguori@amazon.com, Will Deacon , daniel.gruss@iaik.tugraz.at Subject: [patch 41/60] x86/mm/kpti: Share entry text PMD References: <20171204140706.296109558@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=x86-kpti--Clone_entry_text_PMD.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner Share the entry text PMD of the kernel mapping with the user space mapping. If large pages are enabled this is a single PMD entry and at the point where it is copied into the user page table the RW bit has not been cleared yet. Clear it right away so the user space visible map becomes RX. Signed-off-by: Thomas Gleixner --- arch/x86/mm/kpti.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/arch/x86/mm/kpti.c +++ b/arch/x86/mm/kpti.c @@ -184,6 +184,15 @@ static void __init kpti_clone_user_share } /* + * Clone the populated PMDs of the entry and irqentry text and force it RO. + */ +static void __init kpti_clone_entry_text(void) +{ + kpti_clone_pmds((unsigned long) __entry_text_start, + (unsigned long) __irqentry_text_end, _PAGE_RW); +} + +/* * Ensure that the top level of the user page tables are entirely * populated. This ensures that all processes that get forked have the * same entries. This way, we do not have to ever go set up new entries in @@ -234,4 +243,5 @@ void __init kpti_init(void) kpti_init_all_pgds(); kpti_clone_user_shared(); + kpti_clone_entry_text(); }