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         pud_t *new_pud, *init_pud;
  27         pmd_t *new_pmd, *init_pmd;
  28         pte_t *new_pte, *init_pte;
  29
  30         new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 2);
  31         if (!new_pgd)
  32                 goto no_pgd;
  33
  34         memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
  35
  36         /*
  37          * Copy over the kernel and IO PGD entries
  38          */
  39         init_pgd = pgd_offset_k(0);
  40         memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
  41                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
  42
  43         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
  44
  45         if (!vectors_high()) {
  46                 /*
  47                  * On ARM, first page must always be allocated since it
  48                  * contains the machine vectors.
  49                  */
  50                 new_pud = pud_alloc(mm, new_pgd, 0);
  51                 if (!new_pud)
  52                         goto no_pud;
  53
  54                 new_pmd = pmd_alloc(mm, new_pud, 0);
  55                 if (!new_pmd)
  56                         goto no_pmd;
  57
  58                 new_pte = pte_alloc_map(mm, NULL, new_pmd, 0);
  59                 if (!new_pte)
  60                         goto no_pte;
  61
  62                 init_pud = pud_offset(init_pgd, 0);
  63                 init_pmd = pmd_offset(init_pud, 0);
  64                 init_pte = pte_offset_map(init_pmd, 0);
  65                 set_pte_ext(new_pte, *init_pte, 0);
  66                 pte_unmap(init_pte);
  67                 pte_unmap(new_pte);
  68         }
  69
  70         return new_pgd;
  71
  72 no_pte:
  73         pmd_free(mm, new_pmd);
  74 no_pmd:
  75         pud_free(mm, new_pud);
  76 no_pud:
  77         free_pages((unsigned long)new_pgd, 2);
  78 no_pgd:
  79         return NULL;
  80 }
  81
  82 void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
  83 {
  84         pgd_t *pgd;
  85         pud_t *pud;
  86         pmd_t *pmd;
  87         pgtable_t pte;
  88
  89         if (!pgd_base)
  90                 return;
  91
  92         pgd = pgd_base + pgd_index(0);
  93         if (pgd_none_or_clear_bad(pgd))
  94                 goto no_pgd;
  95
  96         pud = pud_offset(pgd, 0);
  97         if (pud_none_or_clear_bad(pud))
  98                 goto no_pud;
  99
 100         pmd = pmd_offset(pud, 0);
 101         if (pmd_none_or_clear_bad(pmd))
 102                 goto no_pmd;
 103
 104         pte = pmd_pgtable(*pmd);
 105         pmd_clear(pmd);
 106         pte_free(mm, pte);
 107 no_pmd:
 108         pud_clear(pud);
 109         pmd_free(mm, pmd);
 110 no_pud:
 111         pgd_clear(pgd);
 112         pud_free(mm, pud);
 113 no_pgd:
 114         free_pages((unsigned long) pgd_base, 2);
 115 }