From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f53.google.com (mail-oi0-f53.google.com [209.85.218.53]) by kanga.kvack.org (Postfix) with ESMTP id 4BDD36B0253 for ; Fri, 10 Jul 2015 17:16:23 -0400 (EDT) Received: by oiyy130 with SMTP id y130so219763369oiy.0 for ; Fri, 10 Jul 2015 14:16:23 -0700 (PDT) Received: from g1t5424.austin.hp.com (g1t5424.austin.hp.com. [15.216.225.54]) by mx.google.com with ESMTPS id b5si7676767oej.10.2015.07.10.14.16.22 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 10 Jul 2015 14:16:22 -0700 (PDT) Message-ID: <1436562922.3214.124.camel@hp.com> Subject: Re: [PATCH 1/2] x86: Fix pXd_flags() to handle _PAGE_PAT_LARGE From: Toshi Kani Date: Fri, 10 Jul 2015 15:15:22 -0600 In-Reply-To: <559F4293.1090801@suse.com> References: <1436461431-27305-1-git-send-email-toshi.kani@hp.com> <1436461431-27305-2-git-send-email-toshi.kani@hp.com> <559F4293.1090801@suse.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Juergen Gross , hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com Cc: akpm@linux-foundation.org, bp@alien8.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, konrad.wilk@oracle.com, elliott@hp.com On Fri, 2015-07-10 at 05:57 +0200, Juergen Gross wrote: > On 07/09/2015 07:03 PM, Toshi Kani wrote: > > The PAT bit gets relocated to bit 12 when PUD and PMD mappings are > > used. This bit 12, however, is not covered by PTE_FLAGS_MASK, > > which > > is corrently used for masking the flag bits for all cases. > > > > Fix pud_flags() and pmd_flags() to cover the PAT bit, > > _PAGE_PAT_LARGE, > > when they are used to map a large page with _PAGE_PSE set. : > Hmm, I think this covers only half of the problem. pud_pfn() and > pmd_pfn() will return wrong results for large pages with PAT bit > set as well. > > I'd rather use something like: > > static inline unsigned long pmd_pfn_mask(pmd_t pmd) > { > if (pmd_large(pmd)) > return PMD_PAGE_MASK & PHYSICAL_PAGE_MASK; > else > return PTE_PFN_MASK; > } > > static inline unsigned long pmd_flags_mask(pmd_t pmd) > { > if (pmd_large(pmd)) > return ~(PMD_PAGE_MASK & PHYSICAL_PAGE_MASK); > else > return ~PTE_PFN_MASK; > } > > static inline unsigned long pmd_pfn(pmd_t pmd) > { > return (pmd_val(pmd) & pmd_pfn_mask(pmd)) >> PAGE_SHIFT; > } > > static inline pmdval_t pmd_flags(pmd_t pmd) > { > return native_pmd_val(pmd) & ~pmd_flags_mask(pmd); > } Thanks for the suggestion! I agree that it is cleaner in this way. I am updating the patches and found the following changes are needed as well: - Define PGTABLE_LEVELS to 2 in "arch/x86/entry/vdso/vdso32/vclock_gettime.c". This file redefines to X86_32. Setting to 2 levels (since X86_PAE is not set) allows be included to define PMD_SHIFT. - Move PUD_PAGE_SIZE & PUD_PAGE_MASK from to . This allows X86_32 to refer the PUD macros. - Nit: pmd_large() cannot be used in pmd_xxx_mask() since it calls pmd_flags(). Use (native_pud_val(pud) & _PAGE_PSE), instead. Thanks, -Toshi -- 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