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/highmem.h>
  12
  13 #include <asm/pgalloc.h>
  14 #include <asm/page.h>
  15 #include <asm/tlbflush.h>
  16
  17 #include "mm.h"
  18
  19 #define FIRST_KERNEL_PGD_NR     (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
  20
  21 /*
  22  * need to get a 16k page for level 1
  23  */
  24 pgd_t *get_pgd_slow(struct mm_struct *mm)
  25 {
  26         pgd_t *new_pgd, *init_pgd;
  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, FIRST_KERNEL_PGD_NR * 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 + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
  41                        (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * 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_pmd = pmd_alloc(mm, new_pgd, 0);
  51                 if (!new_pmd)
  52                         goto no_pmd;
  53
  54                 new_pte = pte_alloc_map(mm, new_pmd, 0);
  55                 if (!new_pte)
  56                         goto no_pte;
  57
  58                 init_pmd = pmd_offset(init_pgd, 0);
  59                 init_pte = pte_offset_map_nested(init_pmd, 0);
  60                 set_pte_ext(new_pte, *init_pte, 0);
  61                 pte_unmap_nested(init_pte);
  62                 pte_unmap(new_pte);
  63         }
  64
  65         return new_pgd;
  66
  67 no_pte:
  68         pmd_free(mm, new_pmd);
  69 no_pmd:
  70         free_pages((unsigned long)new_pgd, 2);
  71 no_pgd:
  72         return NULL;
  73 }
  74
  75 void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd)
  76 {
  77         pmd_t *pmd;
  78         pgtable_t pte;
  79
  80         if (!pgd)
  81                 return;
  82
  83         /* pgd is always present and good */
  84         pmd = pmd_off(pgd, 0);
  85         if (pmd_none(*pmd))
  86                 goto free;
  87         if (pmd_bad(*pmd)) {
  88                 pmd_ERROR(*pmd);
  89                 pmd_clear(pmd);
  90                 goto free;
  91         }
  92
  93         pte = pmd_pgtable(*pmd);
  94         pmd_clear(pmd);
  95         pte_free(mm, pte);
  96         pmd_free(mm, pmd);
  97 free:
  98         free_pages((unsigned long) pgd, 2);
  99 }