arch/nios2/mm/pgtable.c

   1 /*
   2  * Copyright (C) 2009 Wind River Systems Inc
   3  *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
   4  *
   5  * This file is subject to the terms and conditions of the GNU General Public
   6  * License.  See the file "COPYING" in the main directory of this archive
   7  * for more details.
   8  */
   9
  10 #include <linux/mm.h>
  11 #include <linux/sched.h>
  12
  13 #include <asm/cpuinfo.h>
  14
  15 /* pteaddr:
  16  *   ptbase | vpn* | zero
  17  *   31-22  | 21-2 | 1-0
  18  *
  19  *   *vpn is preserved on double fault
  20  *
  21  * tlbacc:
  22  *   IG   |*flags| pfn
  23  *   31-25|24-20 | 19-0
  24  *
  25  *   *crwxg
  26  *
  27  * tlbmisc:
  28  *   resv  |way   |rd | we|pid |dbl|bad|perm|d
  29  *   31-24 |23-20 |19 | 20|17-4|3  |2  |1   |0
  30  *
  31  */
  32
  33 /*
  34  * Initialize a new pgd / pmd table with invalid pointers.
  35  */
  36 static void pgd_init(pgd_t *pgd)
  37 {
  38         unsigned long *p = (unsigned long *) pgd;
  39         int i;
  40
  41         for (i = 0; i < USER_PTRS_PER_PGD; i += 8) {
  42                 p[i + 0] = (unsigned long) invalid_pte_table;
  43                 p[i + 1] = (unsigned long) invalid_pte_table;
  44                 p[i + 2] = (unsigned long) invalid_pte_table;
  45                 p[i + 3] = (unsigned long) invalid_pte_table;
  46                 p[i + 4] = (unsigned long) invalid_pte_table;
  47                 p[i + 5] = (unsigned long) invalid_pte_table;
  48                 p[i + 6] = (unsigned long) invalid_pte_table;
  49                 p[i + 7] = (unsigned long) invalid_pte_table;
  50         }
  51 }
  52
  53 pgd_t *pgd_alloc(struct mm_struct *mm)
  54 {
  55         pgd_t *ret, *init;
  56
  57         ret = (pgd_t *) __get_free_page(GFP_KERNEL);
  58         if (ret) {
  59                 init = pgd_offset(&init_mm, 0UL);
  60                 pgd_init(ret);
  61                 memcpy(ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
  62                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
  63         }
  64
  65         return ret;
  66 }
  67
  68 void __init pagetable_init(void)
  69 {
  70         /* Initialize the entire pgd.  */
  71         pgd_init(swapper_pg_dir);
  72         pgd_init(swapper_pg_dir + USER_PTRS_PER_PGD);
  73 }