From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 2A7586B02EC for ; Wed, 8 Nov 2017 14:47:17 -0500 (EST) Received: by mail-pg0-f72.google.com with SMTP id r18so3561461pgu.9 for ; Wed, 08 Nov 2017 11:47:17 -0800 (PST) Received: from mga06.intel.com (mga06.intel.com. [134.134.136.31]) by mx.google.com with ESMTPS id r28si4496275pgu.451.2017.11.08.11.47.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 Nov 2017 11:47:16 -0800 (PST) Subject: [PATCH 10/30] x86, kaiser: allow NX to be set in p4d/pgd From: Dave Hansen Date: Wed, 08 Nov 2017 11:47:04 -0800 References: <20171108194646.907A1942@viggo.jf.intel.com> In-Reply-To: <20171108194646.907A1942@viggo.jf.intel.com> Message-Id: <20171108194704.62B7DBCE@viggo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: 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, richard.fellner@student.tugraz.at, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, x86@kernel.org From: Dave Hansen 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: Richard Fellner 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 2017-11-08 10:45:31.308681390 -0800 +++ b/arch/x86/include/asm/pgtable.h 2017-11-08 10:45:31.312681390 -0800 @@ -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) _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org