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 #define FIRST_KERNEL_PGD_NR     (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
  21
  22 /*
  23  * need to get a 16k page for level 1
  24  */
  25 pgd_t *get_pgd_slow(struct mm_struct *mm)
  26 {
  27         pgd_t *new_pgd, *init_pgd;
  28         pmd_t *new_pmd, *init_pmd;
  29         pte_t *new_pte, *init_pte;
  30
  31         new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 2);
  32         if (!new_pgd)
  33                 goto no_pgd;
  34
  35         memset(new_pgd, 0, FIRST_KERNEL_PGD_NR * sizeof(pgd_t));
  36
  37         /*
  38          * Copy over the kernel and IO PGD entries
  39          */
  40         init_pgd = pgd_offset_k(0);
  41         memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
  42                        (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
  43
  44         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
  45
  46         if (!vectors_high()) {
  47                 /*
  48                  * On ARM, first page must always be allocated since it
  49                  * contains the machine vectors.
  50                  */
  51                 new_pmd = pmd_alloc(mm, new_pgd, 0);
  52                 if (!new_pmd)
  53                         goto no_pmd;
  54
  55                 new_pte = pte_alloc_map(mm, new_pmd, 0);
  56                 if (!new_pte)
  57                         goto no_pte;
  58
  59                 init_pmd = pmd_offset(init_pgd, 0);
  60                 init_pte = pte_offset_map_nested(init_pmd, 0);
  61                 set_pte_ext(new_pte, *init_pte, 0);
  62                 pte_unmap_nested(init_pte);
  63                 pte_unmap(new_pte);
  64         }
  65
  66         return new_pgd;
  67
  68 no_pte:
  69         pmd_free(mm, new_pmd);
  70 no_pmd:
  71         free_pages((unsigned long)new_pgd, 2);
  72 no_pgd:
  73         return NULL;
  74 }
  75
  76 void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd)
  77 {
  78         pmd_t *pmd;
  79         pgtable_t pte;
  80
  81         if (!pgd)
  82                 return;
  83
  84         /* pgd is always present and good */
  85         pmd = pmd_off(pgd, 0);
  86         if (pmd_none(*pmd))
  87                 goto free;
  88         if (pmd_bad(*pmd)) {
  89                 pmd_ERROR(*pmd);
  90                 pmd_clear(pmd);
  91                 goto free;
  92         }
  93
  94         pte = pmd_pgtable(*pmd);
  95         pmd_clear(pmd);
  96         pte_free(mm, pte);
  97         pmd_free(mm, pmd);
  98 free:
  99         free_pages((unsigned long) pgd, 2);
 100 }