LXR linux/arch/arm/mm/hugetlbpage.c

   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
  39pte_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
  55struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
  56                              int write)
  57{
  58        return ERR_PTR(-EINVAL);
  59}
  60
  61int pud_huge(pud_t pud)
  62{
  63        return 0;
  64}
  65
  66int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
  67{
  68        return 0;
  69}
  70
  71pte_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
  86struct page *
  87follow_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
  98int pmd_huge(pmd_t pmd)
  99{
 100        return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
 101}
 102