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/cp15.h>
  16 #include <asm/pgalloc.h>
  17 #include <asm/page.h>
  18 #include <asm/tlbflush.h>
  19
  20 #include "mm.h"
  21
  22 #ifdef CONFIG_ARM_LPAE
  23 #define __pgd_alloc()   kmalloc(PTRS_PER_PGD * sizeof(pgd_t), GFP_KERNEL)
  24 #define __pgd_free(pgd) kfree(pgd)
  25 #else
  26 #define __pgd_alloc()   (pgd_t *)__get_free_pages(GFP_KERNEL, 2)
  27 #define __pgd_free(pgd) free_pages((unsigned long)pgd, 2)
  28 #endif
  29
  30 /*
  31  * need to get a 16k page for level 1
  32  */
  33 pgd_t *pgd_alloc(struct mm_struct *mm)
  34 {
  35         pgd_t *new_pgd, *init_pgd;
  36         pud_t *new_pud, *init_pud;
  37         pmd_t *new_pmd, *init_pmd;
  38         pte_t *new_pte, *init_pte;
  39
  40         new_pgd = __pgd_alloc();
  41         if (!new_pgd)
  42                 goto no_pgd;
  43
  44         memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
  45
  46         /*
  47          * Copy over the kernel and IO PGD entries
  48          */
  49         init_pgd = pgd_offset_k(0);
  50         memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
  51                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
  52
  53         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
  54
  55 #ifdef CONFIG_ARM_LPAE
  56         /*
  57          * Allocate PMD table for modules and pkmap mappings.
  58          */
  59         new_pud = pud_alloc(mm, new_pgd + pgd_index(MODULES_VADDR),
  60                             MODULES_VADDR);
  61         if (!new_pud)
  62                 goto no_pud;
  63
  64         new_pmd = pmd_alloc(mm, new_pud, 0);
  65         if (!new_pmd)
  66                 goto no_pmd;
  67 #endif
  68
  69         if (!vectors_high()) {
  70                 /*
  71                  * On ARM, first page must always be allocated since it
  72                  * contains the machine vectors. The vectors are always high
  73                  * with LPAE.
  74                  */
  75                 new_pud = pud_alloc(mm, new_pgd, 0);
  76                 if (!new_pud)
  77                         goto no_pud;
  78
  79                 new_pmd = pmd_alloc(mm, new_pud, 0);
  80                 if (!new_pmd)
  81                         goto no_pmd;
  82
  83                 new_pte = pte_alloc_map(mm, new_pmd, 0);
  84                 if (!new_pte)
  85                         goto no_pte;
  86
  87 #ifndef CONFIG_ARM_LPAE
  88                 /*
  89                  * Modify the PTE pointer to have the correct domain.  This
  90                  * needs to be the vectors domain to avoid the low vectors
  91                  * being unmapped.
  92                  */
  93                 pmd_val(*new_pmd) &= ~PMD_DOMAIN_MASK;
  94                 pmd_val(*new_pmd) |= PMD_DOMAIN(DOMAIN_VECTORS);
  95 #endif
  96
  97                 init_pud = pud_offset(init_pgd, 0);
  98                 init_pmd = pmd_offset(init_pud, 0);
  99                 init_pte = pte_offset_map(init_pmd, 0);
 100                 set_pte_ext(new_pte + 0, init_pte[0], 0);
 101                 set_pte_ext(new_pte + 1, init_pte[1], 0);
 102                 pte_unmap(init_pte);
 103                 pte_unmap(new_pte);
 104         }
 105
 106         return new_pgd;
 107
 108 no_pte:
 109         pmd_free(mm, new_pmd);
 110         mm_dec_nr_pmds(mm);
 111 no_pmd:
 112         pud_free(mm, new_pud);
 113 no_pud:
 114         __pgd_free(new_pgd);
 115 no_pgd:
 116         return NULL;
 117 }
 118
 119 void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
 120 {
 121         pgd_t *pgd;
 122         pud_t *pud;
 123         pmd_t *pmd;
 124         pgtable_t pte;
 125
 126         if (!pgd_base)
 127                 return;
 128
 129         pgd = pgd_base + pgd_index(0);
 130         if (pgd_none_or_clear_bad(pgd))
 131                 goto no_pgd;
 132
 133         pud = pud_offset(pgd, 0);
 134         if (pud_none_or_clear_bad(pud))
 135                 goto no_pud;
 136
 137         pmd = pmd_offset(pud, 0);
 138         if (pmd_none_or_clear_bad(pmd))
 139                 goto no_pmd;
 140
 141         pte = pmd_pgtable(*pmd);
 142         pmd_clear(pmd);
 143         pte_free(mm, pte);
 144         atomic_long_dec(&mm->nr_ptes);
 145 no_pmd:
 146         pud_clear(pud);
 147         pmd_free(mm, pmd);
 148         mm_dec_nr_pmds(mm);
 149 no_pud:
 150         pgd_clear(pgd);
 151         pud_free(mm, pud);
 152 no_pgd:
 153 #ifdef CONFIG_ARM_LPAE
 154         /*
 155          * Free modules/pkmap or identity pmd tables.
 156          */
 157         for (pgd = pgd_base; pgd < pgd_base + PTRS_PER_PGD; pgd++) {
 158                 if (pgd_none_or_clear_bad(pgd))
 159                         continue;
 160                 if (pgd_val(*pgd) & L_PGD_SWAPPER)
 161                         continue;
 162                 pud = pud_offset(pgd, 0);
 163                 if (pud_none_or_clear_bad(pud))
 164                         continue;
 165                 pmd = pmd_offset(pud, 0);
 166                 pud_clear(pud);
 167                 pmd_free(mm, pmd);
 168                 mm_dec_nr_pmds(mm);
 169                 pgd_clear(pgd);
 170                 pud_free(mm, pud);
 171         }
 172 #endif
 173         __pgd_free(pgd_base);
 174 }