Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751505Ab0KPPSJ (ORCPT ); Tue, 16 Nov 2010 10:18:09 -0500 Received: from mail-iw0-f174.google.com ([209.85.214.174]:60201 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751014Ab0KPPSH convert rfc822-to-8bit (ORCPT ); Tue, 16 Nov 2010 10:18:07 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=N8t8t9Zpvx0i1fCbcN6NJiP+B56V5igQJEt52DSqA4Y8otcg5mWc5I2Iyh1Z1GmHSL 7IVEl08e+82IefF51TuoFFjlXpemAfkO/W3rtCQC7/7sWgn1PLM0LYxmEVxglPvr/3s7 hh1sRkRwvTM9kcuxox87ywRjWi8RDunNNXhq8= MIME-Version: 1.0 In-Reply-To: <20101115183014.GD31421@n2100.arm.linux.org.uk> References: <1289584840-18097-1-git-send-email-catalin.marinas@arm.com> <1289584840-18097-6-git-send-email-catalin.marinas@arm.com> <20101115183014.GD31421@n2100.arm.linux.org.uk> Date: Tue, 16 Nov 2010 15:18:03 +0000 X-Google-Sender-Auth: PQzsoYa0zIcOqWOPCR5pHmxXsaA Message-ID: Subject: Re: [PATCH v2 05/20] ARM: LPAE: Introduce L_PTE_NOEXEC and L_PTE_NOWRITE From: Catalin Marinas To: Russell King - ARM Linux Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2040 Lines: 47 On 15 November 2010 18:30, Russell King - ARM Linux wrote: > On Fri, Nov 12, 2010 at 06:00:25PM +0000, Catalin Marinas wrote: >> The LPAE page table format needs to explicitly disable execution or >> write permissions on a page by setting the corresponding bits (similar >> to the classic page table format with Access Flag enabled). This patch >> introduces null definitions for the 2-level format and the actual noexec >> and nowrite bits for the LPAE format. It also changes several PTE >> maintenance macros and masks. >> >> Signed-off-by: Catalin Marinas >> --- >> ?arch/arm/include/asm/pgtable-2level.h | ? ?2 + >> ?arch/arm/include/asm/pgtable.h ? ? ? ?| ? 44 +++++++++++++++++++++------------ >> ?arch/arm/mm/mmu.c ? ? ? ? ? ? ? ? ? ? | ? ?6 ++-- >> ?3 files changed, 33 insertions(+), 19 deletions(-) >> >> diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h >> index 36bdef7..4e21166 100644 >> --- a/arch/arm/include/asm/pgtable-2level.h >> +++ b/arch/arm/include/asm/pgtable-2level.h >> @@ -128,6 +128,8 @@ >> ?#define L_PTE_USER ? ? ? ? ? (1 << 8) >> ?#define L_PTE_EXEC ? ? ? ? ? (1 << 9) >> ?#define L_PTE_SHARED ? ? ? ? (1 << 10) ? ? ? /* shared(v6), coherent(xsc3) */ >> +#define L_PTE_NOEXEC ? ? ? ? (0) >> +#define L_PTE_NOWRITE ? ? ? ? ? ? ? ?(0) > > Let's not make this more complicated than it has to be. ?If we need the > inverse of WRITE and EXEC, then that's what we should change everyone to, > not invent a new system to work along side the old system. This adds an additional instruction in set_pte_ext, unless you can write the bit checking in a better way: tst r1, #L_PTE_NOWRITE orrne r3, r3, #PTE_EXT_APX tsteq r1, #L_PTE_DIRTY orreq r3, r3, #PTE_EXT_APX -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/