pgd.c 2.1 KB

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  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. #include <asm/pgalloc.h>
  13. #include <asm/page.h>
  14. #include <asm/tlbflush.h>
  15. #include "mm.h"
  16. #define FIRST_KERNEL_PGD_NR (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
  17. /*
  18. * need to get a 16k page for level 1
  19. */
  20. pgd_t *get_pgd_slow(struct mm_struct *mm)
  21. {
  22. pgd_t *new_pgd, *init_pgd;
  23. pmd_t *new_pmd, *init_pmd;
  24. pte_t *new_pte, *init_pte;
  25. new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 2);
  26. if (!new_pgd)
  27. goto no_pgd;
  28. memzero(new_pgd, FIRST_KERNEL_PGD_NR * sizeof(pgd_t));
  29. /*
  30. * Copy over the kernel and IO PGD entries
  31. */
  32. init_pgd = pgd_offset_k(0);
  33. memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
  34. (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
  35. clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
  36. if (!vectors_high()) {
  37. /*
  38. * On ARM, first page must always be allocated since it
  39. * contains the machine vectors.
  40. */
  41. new_pmd = pmd_alloc(mm, new_pgd, 0);
  42. if (!new_pmd)
  43. goto no_pmd;
  44. new_pte = pte_alloc_map(mm, new_pmd, 0);
  45. if (!new_pte)
  46. goto no_pte;
  47. init_pmd = pmd_offset(init_pgd, 0);
  48. init_pte = pte_offset_map_nested(init_pmd, 0);
  49. set_pte_ext(new_pte, *init_pte, 0);
  50. pte_unmap_nested(init_pte);
  51. pte_unmap(new_pte);
  52. }
  53. return new_pgd;
  54. no_pte:
  55. pmd_free(new_pmd);
  56. no_pmd:
  57. free_pages((unsigned long)new_pgd, 2);
  58. no_pgd:
  59. return NULL;
  60. }
  61. void free_pgd_slow(pgd_t *pgd)
  62. {
  63. pmd_t *pmd;
  64. struct page *pte;
  65. if (!pgd)
  66. return;
  67. /* pgd is always present and good */
  68. pmd = pmd_off(pgd, 0);
  69. if (pmd_none(*pmd))
  70. goto free;
  71. if (pmd_bad(*pmd)) {
  72. pmd_ERROR(*pmd);
  73. pmd_clear(pmd);
  74. goto free;
  75. }
  76. pte = pmd_page(*pmd);
  77. pmd_clear(pmd);
  78. dec_zone_page_state(virt_to_page((unsigned long *)pgd), NR_PAGETABLE);
  79. pte_lock_deinit(pte);
  80. pte_free(pte);
  81. pmd_free(pmd);
  82. free:
  83. free_pages((unsigned long) pgd, 2);
  84. }