From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759668AbYESXL1 (ORCPT ); Mon, 19 May 2008 19:11:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755417AbYESXLS (ORCPT ); Mon, 19 May 2008 19:11:18 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:39657 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752989AbYESXLR (ORCPT ); Mon, 19 May 2008 19:11:17 -0400 Date: Mon, 19 May 2008 16:10:02 -0700 (PDT) From: Linus Torvalds To: Hugh Dickins cc: Theodore Tso , Gabriel C , Keith Packard , "Pallipadi, Venkatesh" , Eric Anholt , linux-kernel@vger.kernel.org, Ingo Molnar , "Siddha, Suresh B" , bugme-daemon@bugzilla.kernel.org, airlied@linux.ie, "Barnes, Jesse" , Jeremy Fitzhardinge , Andrew Morton , "Rafael J. Wysocki" Subject: Re: [Bug 10732] REGRESSION: 2.6.26-rc2-git4: X server failed start onX61s laptop In-Reply-To: Message-ID: References: <924EFEDD5F540B4284297C4DC59F3DEE01119AFE@orsmsx423.amr.corp.intel.com> <20080517154131.GA7651@mit.edu> <924EFEDD5F540B4284297C4DC59F3DEE01119B07@orsmsx423.amr.corp.intel.com> <1211047916.27447.314.camel@koto.keithp.com> <482F24C6.2050705@frugalware.org> <20080517184626.GA16496@mit.edu> User-Agent: Alpine 1.10 (LFD 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 19 May 2008, Hugh Dickins wrote: > > This comes from an assumption in 1c12c4cf9411eb130b245fa8d0fbbaf989477c7b > mprotect: prevent alteration of the PAT bits, that PTE_MASK is what it's > supposed to be: whereas it's been wrong forever with PAE, staying 32-bit > where 64-bit is needed. Can we *please* just fix PTE_MASK? And can we agree to never EVER use that PAGE_MASK thing (which was only ever meant to work on *addresses*) for any pte operations (including the definition of PTE_MASK)? Because PAGE_MASK is very much the word-size, and in 32-bit PAE, the page table entry is bigger. IOE, PTE_MASK should be a "pteval_t". And it should have absolutely *nothing* to do with PAGE_MASK. EVER. IOW, maybe something like this? And no, I haven't tested this at all. But it should make PTE_MASK have (a) the right type ("pteval_t", not "long" - the latter is pure and utter crap) (b) the right value (proper mask, not a sign-extended long - again, the latter is pure and utter crap) but for all I know there might be some broken code that depends on the current incorrect and totally broken #defines, so this needs testing and thinking about. It also causes these warnings on 32-bit PAE: AS arch/x86/kernel/head_32.o arch/x86/kernel/head_32.S: Assembler messages: arch/x86/kernel/head_32.S:225: Warning: left operand is a bignum; integer 0 assumed arch/x86/kernel/head_32.S:609: Warning: left operand is a bignum; integer 0 assumed and I do not see why (the end result seems to be identical). Ingo, comments? Oh, and those #define's should be moved from to , I think. They have nothing to do with pages (despite the name of "physical_page_mask", and really are meaningful only in the context of some kind of page table entry. Linus --- include/asm-x86/page.h | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/include/asm-x86/page.h b/include/asm-x86/page.h index b381f4a..34b4845 100644 --- a/include/asm-x86/page.h +++ b/include/asm-x86/page.h @@ -10,8 +10,8 @@ #ifdef __KERNEL__ -#define PHYSICAL_PAGE_MASK (PAGE_MASK & __PHYSICAL_MASK) -#define PTE_MASK (_AT(long, PHYSICAL_PAGE_MASK)) +#define PHYSICAL_PAGE_MASK (__PHYSICAL_MASK & ~__PHYSICAL_LOW_BITS) +#define PTE_MASK (_AT(pteval_t, PHYSICAL_PAGE_MASK)) #define PMD_PAGE_SIZE (_AC(1, UL) << PMD_SHIFT) #define PMD_PAGE_MASK (~(PMD_PAGE_SIZE-1)) @@ -24,6 +24,7 @@ /* to align the pointer to the (next) page boundary */ #define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK) +#define __PHYSICAL_LOW_BITS _AT(phys_addr_t, (PAGE_SIZE-1)) #define __PHYSICAL_MASK _AT(phys_addr_t, (_AC(1,ULL) << __PHYSICAL_MASK_SHIFT) - 1) #define __VIRTUAL_MASK ((_AC(1,UL) << __VIRTUAL_MASK_SHIFT) - 1)