From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f171.google.com (mail-pf0-f171.google.com [209.85.192.171]) by kanga.kvack.org (Postfix) with ESMTP id F2837828F3 for ; Fri, 12 Feb 2016 16:02:29 -0500 (EST) Received: by mail-pf0-f171.google.com with SMTP id x65so53108886pfb.1 for ; Fri, 12 Feb 2016 13:02:29 -0800 (PST) Received: from mga03.intel.com (mga03.intel.com. [134.134.136.65]) by mx.google.com with ESMTP id dg7si22158755pad.75.2016.02.12.13.02.18 for ; Fri, 12 Feb 2016 13:02:18 -0800 (PST) Subject: [PATCH 18/33] x86, mm: simplify get_user_pages() PTE bit handling From: Dave Hansen Date: Fri, 12 Feb 2016 13:02:18 -0800 References: <20160212210152.9CAD15B0@viggo.jf.intel.com> In-Reply-To: <20160212210152.9CAD15B0@viggo.jf.intel.com> Message-Id: <20160212210218.3A2D4045@viggo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, x86@kernel.org, torvalds@linux-foundation.org, Dave Hansen , dave.hansen@linux.intel.com 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 Reviewed-by: Thomas Gleixner --- b/arch/x86/mm/gup.c | 38 ++++++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 16 deletions(-) diff -puN arch/x86/mm/gup.c~pkeys-12-gup-swizzle arch/x86/mm/gup.c --- a/arch/x86/mm/gup.c~pkeys-12-gup-swizzle 2016-02-12 10:44:21.572490755 -0800 +++ b/arch/x86/mm/gup.c 2016-02-12 10:44:21.575490892 -0800 @@ -75,6 +75,24 @@ static void undo_dev_pagemap(int *nr, in } /* + * 'pteval' can come from a pte, pmd or pud. We only check + * _PAGE_PRESENT, _PAGE_USER, and _PAGE_RW in here which are the + * same value on all 3 types. + */ +static inline int pte_allows_gup(unsigned long pteval, int write) +{ + unsigned long need_pte_bits = _PAGE_PRESENT|_PAGE_USER; + + if (write) + need_pte_bits |= _PAGE_RW; + + if ((pteval & need_pte_bits) != need_pte_bits) + return 0; + + return 1; +} + +/* * The performance critical leaf functions are made noinline otherwise gcc * inlines everything into a single function which results in too much * register pressure. @@ -83,14 +101,9 @@ static noinline int gup_pte_range(pmd_t unsigned long end, int write, struct page **pages, int *nr) { struct dev_pagemap *pgmap = NULL; - unsigned long mask; int nr_start = *nr; 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); @@ -110,7 +123,8 @@ static noinline int gup_pte_range(pmd_t pte_unmap(ptep); return 0; } - } else if ((pte_flags(pte) & (mask | _PAGE_SPECIAL)) != mask) { + } else if (!pte_allows_gup(pte_val(pte), write) || + pte_special(pte)) { pte_unmap(ptep); return 0; } @@ -164,14 +178,10 @@ static int __gup_device_huge_pmd(pmd_t p 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 (!pte_allows_gup(pmd_val(pmd), write)) return 0; VM_BUG_ON(!pfn_valid(pmd_pfn(pmd))); @@ -231,14 +241,10 @@ 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 (!pte_allows_gup(pud_val(pud), write)) return 0; /* hugepages are never "special" */ VM_BUG_ON(pud_flags(pud) & _PAGE_SPECIAL); _ -- 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