arch/arm/mm/pgd.c

   1 /*
   2  *  linux/arch/arm/mm/pgd.c
   3  *
   4  *  Copyright (C) 1998-2005 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/mm.h>
  11 #include <linux/gfp.h>
  12 #include <linux/highmem.h>
  13
  14 #include <asm/pgalloc.h>
  15 #include <asm/page.h>
  16 #include <asm/tlbflush.h>
  17
  18 #include "mm.h"
  19
  20 /*
  21  * need to get a 16k page for level 1
  22  */
  23 pgd_t *pgd_alloc(struct mm_struct *mm)
  24 {
  25         pgd_t *new_pgd, *init_pgd;
  26         pmd_t *new_pmd, *init_pmd;
  27         pte_t *new_pte, *init_pte;
  28
  29         new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 2);
  30         if (!new_pgd)
  31                 goto no_pgd;
  32
  33         memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
  34
  35         /*
  36          * Copy over the kernel and IO PGD entries
  37          */
  38         init_pgd = pgd_offset_k(0);
  39         memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
  40                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
  41
  42         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
  43
  44         if (!vectors_high()) {
  45                 /*
  46                  * On ARM, first page must always be allocated since it
  47                  * contains the machine vectors.
  48                  */
  49                 new_pmd = pmd_alloc(mm, new_pgd, 0);
  50                 if (!new_pmd)
  51                         goto no_pmd;
  52
  53                 new_pte = pte_alloc_map(mm, NULL, new_pmd, 0);
  54                 if (!new_pte)
  55                         goto no_pte;
  56
  57                 init_pmd = pmd_offset(init_pgd, 0);
  58                 init_pte = pte_offset_map(init_pmd, 0);
  59                 set_pte_ext(new_pte, *init_pte, 0);
  60                 pte_unmap(init_pte);
  61                 pte_unmap(new_pte);
  62         }
  63
  64         return new_pgd;
  65
  66 no_pte:
  67         pmd_free(mm, new_pmd);
  68 no_pmd:
  69         free_pages((unsigned long)new_pgd, 2);
  70 no_pgd:
  71         return NULL;
  72 }
  73
  74 void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
  75 {
  76         pgd_t *pgd;
  77         pmd_t *pmd;
  78         pgtable_t pte;
  79
  80         if (!pgd_base)
  81                 return;
  82
  83         pgd = pgd_base + pgd_index(0);
  84         if (pgd_none_or_clear_bad(pgd))
  85                 goto no_pgd;
  86
  87         pmd = pmd_offset(pgd, 0);
  88         if (pmd_none_or_clear_bad(pmd))
  89                 goto no_pmd;
  90
  91         pte = pmd_pgtable(*pmd);
  92         pmd_clear(pmd);
  93         pte_free(mm, pte);
  94 no_pmd:
  95         pgd_clear(pgd);
  96         pmd_free(mm, pmd);
  97 no_pgd:
  98         free_pages((unsigned long) pgd_base, 2);
  99 }