From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 11FFD6B0005 for ; Tue, 7 Aug 2018 06:24:37 -0400 (EDT) Received: by mail-ed1-f72.google.com with SMTP id f8-v6so5227794eds.6 for ; Tue, 07 Aug 2018 03:24:37 -0700 (PDT) Received: from theia.8bytes.org (8bytes.org. [2a01:238:4383:600:38bc:a715:4b6d:a889]) by mx.google.com with ESMTPS id t18-v6si664794edf.80.2018.08.07.03.24.35 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Aug 2018 03:24:35 -0700 (PDT) From: Joerg Roedel Subject: [PATCH 2/3] x86/mm/pti: Don't clear permissions in pti_clone_pmd() Date: Tue, 7 Aug 2018 12:24:30 +0200 Message-Id: <1533637471-30953-3-git-send-email-joro@8bytes.org> In-Reply-To: <1533637471-30953-1-git-send-email-joro@8bytes.org> References: <1533637471-30953-1-git-send-email-joro@8bytes.org> Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waiman Long , Pavel Machek , "David H . Gutteridge" , jroedel@suse.de, joro@8bytes.org From: Joerg Roedel The function sets the global-bit on cloned PMD entries, which only makes sense when the permissions are identical between the user and the kernel page-table. Further, only write-permissions are cleared for entry-text and kernel-text sections, which are not writeable anyway. Signed-off-by: Joerg Roedel --- arch/x86/mm/pti.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 113ba14..5164c98 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -291,7 +291,7 @@ static void __init pti_setup_vsyscall(void) { } #endif static void -pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear) +pti_clone_pmds(unsigned long start, unsigned long end) { unsigned long addr; @@ -352,7 +352,7 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear) * tables will share the last-level page tables of this * address range */ - *target_pmd = pmd_clear_flags(*pmd, clear); + *target_pmd = *pmd; } } @@ -398,7 +398,7 @@ static void __init pti_clone_user_shared(void) start = CPU_ENTRY_AREA_BASE; end = start + (PAGE_SIZE * CPU_ENTRY_AREA_PAGES); - pti_clone_pmds(start, end, 0); + pti_clone_pmds(start, end); } #endif /* CONFIG_X86_64 */ @@ -418,8 +418,7 @@ static void __init pti_setup_espfix64(void) static void pti_clone_entry_text(void) { pti_clone_pmds((unsigned long) __entry_text_start, - (unsigned long) __irqentry_text_end, - _PAGE_RW); + (unsigned long) __irqentry_text_end); } /* @@ -501,7 +500,7 @@ static void pti_clone_kernel_text(void) * pti_set_kernel_image_nonglobal() did to clear the * global bit. */ - pti_clone_pmds(start, end_clone, _PAGE_RW); + pti_clone_pmds(start, end_clone); /* * pti_clone_pmds() will set the global bit in any PMDs -- 2.7.4