arch/unicore32/mm/pgd.c

   1 /*
   2  * linux/arch/unicore32/mm/pgd.c
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  * Copyright (C) 2001-2010 GUAN Xue-tao
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/mm.h>
  13 #include <linux/gfp.h>
  14 #include <linux/highmem.h>
  15
  16 #include <asm/pgalloc.h>
  17 #include <asm/page.h>
  18 #include <asm/tlbflush.h>
  19
  20 #include "mm.h"
  21
  22 #define FIRST_KERNEL_PGD_NR     (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
  23
  24 /*
  25  * need to get a 4k page for level 1
  26  */
  27 pgd_t *get_pgd_slow(struct mm_struct *mm)
  28 {
  29         pgd_t *new_pgd, *init_pgd;
  30         pmd_t *new_pmd, *init_pmd;
  31         pte_t *new_pte, *init_pte;
  32
  33         new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 0);
  34         if (!new_pgd)
  35                 goto no_pgd;
  36
  37         memset(new_pgd, 0, FIRST_KERNEL_PGD_NR * sizeof(pgd_t));
  38
  39         /*
  40          * Copy over the kernel and IO PGD entries
  41          */
  42         init_pgd = pgd_offset_k(0);
  43         memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
  44                        (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
  45
  46         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
  47
  48         if (!vectors_high()) {
  49                 /*
  50                  * On UniCore, first page must always be allocated since it
  51                  * contains the machine vectors.
  52                  */
  53                 new_pmd = pmd_alloc(mm, (pud_t *)new_pgd, 0);
  54                 if (!new_pmd)
  55                         goto no_pmd;
  56
  57                 new_pte = pte_alloc_map(mm, NULL, new_pmd, 0);
  58                 if (!new_pte)
  59                         goto no_pte;
  60
  61                 init_pmd = pmd_offset((pud_t *)init_pgd, 0);
  62                 init_pte = pte_offset_map(init_pmd, 0);
  63                 set_pte(new_pte, *init_pte);
  64                 pte_unmap(init_pte);
  65                 pte_unmap(new_pte);
  66         }
  67
  68         return new_pgd;
  69
  70 no_pte:
  71         pmd_free(mm, new_pmd);
  72         mm_dec_nr_pmds(mm);
  73 no_pmd:
  74         free_pages((unsigned long)new_pgd, 0);
  75 no_pgd:
  76         return NULL;
  77 }
  78
  79 void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd)
  80 {
  81         pmd_t *pmd;
  82         pgtable_t pte;
  83
  84         if (!pgd)
  85                 return;
  86
  87         /* pgd is always present and good */
  88         pmd = pmd_off(pgd, 0);
  89         if (pmd_none(*pmd))
  90                 goto free;
  91         if (pmd_bad(*pmd)) {
  92                 pmd_ERROR(*pmd);
  93                 pmd_clear(pmd);
  94                 goto free;
  95         }
  96
  97         pte = pmd_pgtable(*pmd);
  98         pmd_clear(pmd);
  99         pte_free(mm, pte);
 100         atomic_long_dec(&mm->nr_ptes);
 101         pmd_free(mm, pmd);
 102         mm_dec_nr_pmds(mm);
 103 free:
 104         free_pages((unsigned long) pgd, 0);
 105 }