From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753630AbdKXJUz (ORCPT ); Fri, 24 Nov 2017 04:20:55 -0500 Received: from mail-wr0-f196.google.com ([209.85.128.196]:42225 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753278AbdKXJPo (ORCPT ); Fri, 24 Nov 2017 04:15:44 -0500 X-Google-Smtp-Source: AGs4zMbBbHCJhDVYJC8UsDkFmt5q3AMH5PnI7fhRCbA5TIbY6WeP80L8UvOAFxeUnARnr/e4ORXpuw== From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Dave Hansen , Andy Lutomirski , Thomas Gleixner , "H . Peter Anvin" , Peter Zijlstra , Borislav Petkov , Linus Torvalds Subject: [PATCH 26/43] x86/mm/kaiser: Allow NX poison to be set in p4d/pgd Date: Fri, 24 Nov 2017 10:14:31 +0100 Message-Id: <20171124091448.7649-27-mingo@kernel.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171124091448.7649-1-mingo@kernel.org> References: <20171124091448.7649-1-mingo@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen The user portion of the kernel page tables use the NX bit to poison them for userspace. But, that trips the p4d/pgd_bad() checks. Make sure it does not do that. Signed-off-by: Dave Hansen Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Daniel Gruss Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Kees Cook Cc: Linus Torvalds Cc: Michael Schwarz Cc: Moritz Lipp Cc: Peter Zijlstra Cc: Richard Fellner Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20171123003448.C6AB3575@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/pgtable.h | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index d3901124143f..9cceaf6c0405 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -846,7 +846,12 @@ static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address) 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 */ @@ -880,7 +885,12 @@ static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address) 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) -- 2.14.1