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 #include <linux/slab.h>
  14
  15 #include <asm/pgalloc.h>
  16 #include <asm/page.h>
  17 #include <asm/tlbflush.h>
  18
  19 #include "mm.h"
  20
  21 #ifdef CONFIG_ARM_LPAE
  22 #define __pgd_alloc()   kmalloc(PTRS_PER_PGD * sizeof(pgd_t), GFP_KERNEL)
  23 #define __pgd_free(pgd) kfree(pgd)
  24 #else
  25 #define __pgd_alloc()   (pgd_t *)__get_free_pages(GFP_KERNEL, 2)
  26 #define __pgd_free(pgd) free_pages((unsigned long)pgd, 2)
  27 #endif
  28
  29 /*
  30  * need to get a 16k page for level 1
  31  */
  32 pgd_t *pgd_alloc(struct mm_struct *mm)
  33 {
  34         pgd_t *new_pgd, *init_pgd;
  35         pud_t *new_pud, *init_pud;
  36         pmd_t *new_pmd, *init_pmd;
  37         pte_t *new_pte, *init_pte;
  38
  39         new_pgd = __pgd_alloc();
  40         if (!new_pgd)
  41                 goto no_pgd;
  42
  43         memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
  44
  45         /*
  46          * Copy over the kernel and IO PGD entries
  47          */
  48         init_pgd = pgd_offset_k(0);
  49         memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
  50                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
  51
  52         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
  53
  54 #ifdef CONFIG_ARM_LPAE
  55         /*
  56          * Allocate PMD table for modules and pkmap mappings.
  57          */
  58         new_pud = pud_alloc(mm, new_pgd + pgd_index(MODULES_VADDR),
  59                             MODULES_VADDR);
  60         if (!new_pud)
  61                 goto no_pud;
  62
  63         new_pmd = pmd_alloc(mm, new_pud, 0);
  64         if (!new_pmd)
  65                 goto no_pmd;
  66 #endif
  67
  68         if (!vectors_high()) {
  69                 /*
  70                  * On ARM, first page must always be allocated since it
  71                  * contains the machine vectors. The vectors are always high
  72                  * with LPAE.
  73                  */
  74                 new_pud = pud_alloc(mm, new_pgd, 0);
  75                 if (!new_pud)
  76                         goto no_pud;
  77
  78                 new_pmd = pmd_alloc(mm, new_pud, 0);
  79                 if (!new_pmd)
  80                         goto no_pmd;
  81
  82                 new_pte = pte_alloc_map(mm, NULL, new_pmd, 0);
  83                 if (!new_pte)
  84                         goto no_pte;
  85
  86                 init_pud = pud_offset(init_pgd, 0);
  87                 init_pmd = pmd_offset(init_pud, 0);
  88                 init_pte = pte_offset_map(init_pmd, 0);
  89                 set_pte_ext(new_pte, *init_pte, 0);
  90                 pte_unmap(init_pte);
  91                 pte_unmap(new_pte);
  92         }
  93
  94         return new_pgd;
  95
  96 no_pte:
  97         pmd_free(mm, new_pmd);
  98 no_pmd:
  99         pud_free(mm, new_pud);
 100 no_pud:
 101         __pgd_free(new_pgd);
 102 no_pgd:
 103         return NULL;
 104 }
 105
 106 void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
 107 {
 108         pgd_t *pgd;
 109         pud_t *pud;
 110         pmd_t *pmd;
 111         pgtable_t pte;
 112
 113         if (!pgd_base)
 114                 return;
 115
 116         pgd = pgd_base + pgd_index(0);
 117         if (pgd_none_or_clear_bad(pgd))
 118                 goto no_pgd;
 119
 120         pud = pud_offset(pgd, 0);
 121         if (pud_none_or_clear_bad(pud))
 122                 goto no_pud;
 123
 124         pmd = pmd_offset(pud, 0);
 125         if (pmd_none_or_clear_bad(pmd))
 126                 goto no_pmd;
 127
 128         pte = pmd_pgtable(*pmd);
 129         pmd_clear(pmd);
 130         pte_free(mm, pte);
 131 no_pmd:
 132         pud_clear(pud);
 133         pmd_free(mm, pmd);
 134 no_pud:
 135         pgd_clear(pgd);
 136         pud_free(mm, pud);
 137 no_pgd:
 138 #ifdef CONFIG_ARM_LPAE
 139         /*
 140          * Free modules/pkmap or identity pmd tables.
 141          */
 142         for (pgd = pgd_base; pgd < pgd_base + PTRS_PER_PGD; pgd++) {
 143                 if (pgd_none_or_clear_bad(pgd))
 144                         continue;
 145                 if (pgd_val(*pgd) & L_PGD_SWAPPER)
 146                         continue;
 147                 pud = pud_offset(pgd, 0);
 148                 if (pud_none_or_clear_bad(pud))
 149                         continue;
 150                 pmd = pmd_offset(pud, 0);
 151                 pud_clear(pud);
 152                 pmd_free(mm, pmd);
 153                 pgd_clear(pgd);
 154                 pud_free(mm, pud);
 155         }
 156 #endif
 157         __pgd_free(pgd_base);
 158 }