LXR linux/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_array(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 */
  33pgd_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
 108no_pte:
 109        pmd_free(mm, new_pmd);
 110        mm_dec_nr_pmds(mm);
 111no_pmd:
 112        pud_free(mm, new_pud);
 113no_pud:
 114        __pgd_free(new_pgd);
 115no_pgd:
 116        return NULL;
 117}
 118
 119void 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        mm_dec_nr_ptes(mm);
 145no_pmd:
 146        pud_clear(pud);
 147        pmd_free(mm, pmd);
 148        mm_dec_nr_pmds(mm);
 149no_pud:
 150        pgd_clear(pgd);
 151        pud_free(mm, pud);
 152no_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}
 175