From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933261AbdLRLyc (ORCPT ); Mon, 18 Dec 2017 06:54:32 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:45266 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932677AbdLRLy1 (ORCPT ); Mon, 18 Dec 2017 06:54:27 -0500 Message-Id: <20171218115256.392572732@linutronix.de> User-Agent: quilt/0.63-1 Date: Mon, 18 Dec 2017 12:42:49 +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, Kees Cook , Borislav Petkov Subject: [patch V163 34/51] x86/mm/pti: Map ESPFIX into user space References: <20171218114215.239543034@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=x86-mm-pti--Map-ESPFIX-into-user-space.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Lutomirski Map the ESPFIX pages into user space when PTI is enabled. Move init_espfix_bsp() before pti_init() so it can be correcly populated. Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Cc: Kees Cook Cc: Peter Zijlstra Cc: Brian Gerst Cc: David Laight Cc: Borislav Petkov --- arch/x86/mm/pti.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -232,6 +232,24 @@ pti_clone_pmds(unsigned long start, unsi } } +static void __init pti_setup_espfix64(void) +{ +#ifdef CONFIG_X86_ESPFIX64 + /* + * ESPFIX64 uses a single p4d (i.e. a top-level entry on 4-level + * systems and a next-level entry on 5-level systems. Share that + * entry between the user and kernel pagetables. + */ + pgd_t *kernel_pgd; + p4d_t *kernel_p4d, *user_p4d; + + user_p4d = pti_user_pagetable_walk_p4d(ESPFIX_BASE_ADDR); + kernel_pgd = pgd_offset_k(ESPFIX_BASE_ADDR); + kernel_p4d = p4d_offset(kernel_pgd, ESPFIX_BASE_ADDR); + *user_p4d = *kernel_p4d; +#endif +} + /* * Clone the populated PMDs of the user shared fixmaps into the user space * visible page table. @@ -270,4 +288,5 @@ void __init pti_init(void) pti_clone_user_shared(); pti_clone_entry_text(); + pti_setup_espfix64(); }