From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754080AbdJaWc6 (ORCPT ); Tue, 31 Oct 2017 18:32:58 -0400 Received: from mga14.intel.com ([192.55.52.115]:12072 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933051AbdJaWc0 (ORCPT ); Tue, 31 Oct 2017 18:32:26 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,326,1505804400"; d="scan'208";a="1237918347" Subject: [PATCH 09/23] x86, kaiser: allow NX to be set in p4d/pgd To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, dave.hansen@linux.intel.com, moritz.lipp@iaik.tugraz.at, daniel.gruss@iaik.tugraz.at, michael.schwarz@iaik.tugraz.at, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, x86@kernel.org From: Dave Hansen Date: Tue, 31 Oct 2017 15:32:03 -0700 References: <20171031223146.6B47C861@viggo.jf.intel.com> In-Reply-To: <20171031223146.6B47C861@viggo.jf.intel.com> Message-Id: <20171031223203.9EECAD78@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We protect user portion of the kernel page tables with the NX bit to cripple it. But, that trips the p4d/pgd_bad() checks. Make sure it does not do that. Signed-off-by: Dave Hansen Cc: Moritz Lipp Cc: Daniel Gruss Cc: Michael Schwarz Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Kees Cook Cc: Hugh Dickins Cc: x86@kernel.org --- b/arch/x86/include/asm/pgtable.h | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff -puN arch/x86/include/asm/pgtable.h~kaiser-p4d-allow-nx arch/x86/include/asm/pgtable.h --- a/arch/x86/include/asm/pgtable.h~kaiser-p4d-allow-nx 2017-10-31 15:03:53.299252767 -0700 +++ b/arch/x86/include/asm/pgtable.h 2017-10-31 15:03:53.304253004 -0700 @@ -845,7 +845,12 @@ static inline pud_t *pud_offset(p4d_t *p static inline int p4d_bad(p4d_t p4d) { - return (p4d_flags(p4d) & ~(_KERNPG_TABLE | _PAGE_USER)) != 0; + unsigned long ignore_flags = _KERNPG_TABLE | _PAGE_USER; + + if (IS_ENABLED(CONFIG_KAISER)) + ignore_flags |= _PAGE_NX; + + return (p4d_flags(p4d) & ~ignore_flags) != 0; } #endif /* CONFIG_PGTABLE_LEVELS > 3 */ @@ -879,7 +884,12 @@ static inline p4d_t *p4d_offset(pgd_t *p static inline int pgd_bad(pgd_t pgd) { - return (pgd_flags(pgd) & ~_PAGE_USER) != _KERNPG_TABLE; + unsigned long ignore_flags = _PAGE_USER; + + if (IS_ENABLED(CONFIG_KAISER)) + ignore_flags |= _PAGE_NX; + + return (pgd_flags(pgd) & ~ignore_flags) != _KERNPG_TABLE; } static inline int pgd_none(pgd_t pgd) _