1 /* 2 * arch/arm/mm/hugetlbpage.c 3 * 4 * Copyright (C) 2012 ARM Ltd. 5 * 6 * Based on arch/x86/include/asm/hugetlb.h and Bill Carson's patches 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21 22 #include <linux/init.h> 23 #include <linux/fs.h> 24 #include <linux/mm.h> 25 #include <linux/hugetlb.h> 26 #include <linux/pagemap.h> 27 #include <linux/err.h> 28 #include <linux/sysctl.h> 29 #include <asm/mman.h> 30 #include <asm/tlb.h> 31 #include <asm/tlbflush.h> 32 #include <asm/pgalloc.h> 33 34 /* 35 * On ARM, huge pages are backed by pmd's rather than pte's, so we do a lot 36 * of type casting from pmd_t * to pte_t *. 37 */ 38 39 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) 40 { 41 pgd_t *pgd; 42 pud_t *pud; 43 pmd_t *pmd = NULL; 44 45 pgd = pgd_offset(mm, addr); 46 if (pgd_present(*pgd)) { 47 pud = pud_offset(pgd, addr); 48 if (pud_present(*pud)) 49 pmd = pmd_offset(pud, addr); 50 } 51 52 return (pte_t *)pmd; 53 } 54 55 struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, 56 int write) 57 { 58 return ERR_PTR(-EINVAL); 59 } 60 61 int pud_huge(pud_t pud) 62 { 63 return 0; 64 } 65 66 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) 67 { 68 return 0; 69 } 70 71 pte_t *huge_pte_alloc(struct mm_struct *mm, 72 unsigned long addr, unsigned long sz) 73 { 74 pgd_t *pgd; 75 pud_t *pud; 76 pte_t *pte = NULL; 77 78 pgd = pgd_offset(mm, addr); 79 pud = pud_alloc(mm, pgd, addr); 80 if (pud) 81 pte = (pte_t *)pmd_alloc(mm, pud, addr); 82 83 return pte; 84 } 85 86 struct page * 87 follow_huge_pmd(struct mm_struct *mm, unsigned long address, 88 pmd_t *pmd, int write) 89 { 90 struct page *page; 91 92 page = pte_page(*(pte_t *)pmd); 93 if (page) 94 page += ((address & ~PMD_MASK) >> PAGE_SHIFT); 95 return page; 96 } 97 98 int pmd_huge(pmd_t pmd) 99 { 100 return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT); 101 } 102