From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753266AbbKQDgB (ORCPT ); Mon, 16 Nov 2015 22:36:01 -0500 Received: from mga02.intel.com ([134.134.136.20]:18167 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753244AbbKQDf6 (ORCPT ); Mon, 16 Nov 2015 22:35:58 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,305,1444719600"; d="scan'208";a="852379574" Subject: [PATCH 19/37] x86, mm: simplify get_user_pages() PTE bit handling To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Dave Hansen , dave.hansen@linux.intel.com From: Dave Hansen Date: Mon, 16 Nov 2015 19:35:37 -0800 References: <20151117033511.BFFA1440@viggo.jf.intel.com> In-Reply-To: <20151117033511.BFFA1440@viggo.jf.intel.com> Message-Id: <20151117033537.C2DBB366@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen The current get_user_pages() code is a wee bit more complicated than it needs to be for pte bit checking. Currently, it establishes a mask of required pte _PAGE_* bits and ensures that the pte it goes after has all those bits. This consolidates the three identical copies of this code. Signed-off-by: Dave Hansen --- b/arch/x86/mm/gup.c | 46 +++++++++++++++++++++++++++++----------------- 1 file changed, 29 insertions(+), 17 deletions(-) diff -puN arch/x86/mm/gup.c~pkeys-16-gup-swizzle arch/x86/mm/gup.c --- a/arch/x86/mm/gup.c~pkeys-16-gup-swizzle 2015-11-16 12:35:43.690550937 -0800 +++ b/arch/x86/mm/gup.c 2015-11-16 12:35:43.693551073 -0800 @@ -63,6 +63,31 @@ retry: #endif } +static inline int pte_allows_gup(pte_t pte, int write) +{ + /* + * 'entry_flags' can come from a pte, pmd or pud. Make + * sure to only check flags here that are valid *and* the + * same value on all 3 types. (PAT is currently the only + * one where that is true and is not checked here). + */ + if (!(pte_flags(pte) & (_PAGE_PRESENT|_PAGE_USER))) + return 0; + if (write && !(pte_write(pte))) + return 0; + return 1; +} + +static inline int pmd_allows_gup(pmd_t pmd, int write) +{ + return pte_allows_gup(*(pte_t *)&pmd, write); +} + +static inline int pud_allows_gup(pud_t pud, int write) +{ + return pte_allows_gup(*(pte_t *)&pud, write); +} + /* * The performance critical leaf functions are made noinline otherwise gcc * inlines everything into a single function which results in too much @@ -71,13 +96,8 @@ retry: static noinline int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) { - unsigned long mask; pte_t *ptep; - mask = _PAGE_PRESENT|_PAGE_USER; - if (write) - mask |= _PAGE_RW; - ptep = pte_offset_map(&pmd, addr); do { pte_t pte = gup_get_pte(ptep); @@ -88,8 +108,8 @@ static noinline int gup_pte_range(pmd_t pte_unmap(ptep); return 0; } - - if ((pte_flags(pte) & (mask | _PAGE_SPECIAL)) != mask) { + if (!pte_allows_gup(pte, write) || + pte_special(pte)) { pte_unmap(ptep); return 0; } @@ -117,14 +137,10 @@ static inline void get_head_page_multipl static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) { - unsigned long mask; struct page *head, *page; int refs; - mask = _PAGE_PRESENT|_PAGE_USER; - if (write) - mask |= _PAGE_RW; - if ((pmd_flags(pmd) & mask) != mask) + if (!pmd_allows_gup(pmd, write)) return 0; /* hugepages are never "special" */ VM_BUG_ON(pmd_flags(pmd) & _PAGE_SPECIAL); @@ -193,14 +209,10 @@ static int gup_pmd_range(pud_t pud, unsi static noinline int gup_huge_pud(pud_t pud, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) { - unsigned long mask; struct page *head, *page; int refs; - mask = _PAGE_PRESENT|_PAGE_USER; - if (write) - mask |= _PAGE_RW; - if ((pud_flags(pud) & mask) != mask) + if (!pud_allows_gup(pud, write)) return 0; /* hugepages are never "special" */ VM_BUG_ON(pud_flags(pud) & _PAGE_SPECIAL); _