arch/nds32/mm/mm-nds32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2005-2017 Andes Technology Corporation
   3
   4 #include <linux/init_task.h>
   5
   6 #define __HAVE_ARCH_PGD_FREE
   7 #include <asm/pgalloc.h>
   8
   9 #define FIRST_KERNEL_PGD_NR     (USER_PTRS_PER_PGD)
  10
  11 /*
  12  * need to get a page for level 1
  13  */
  14
  15 pgd_t *pgd_alloc(struct mm_struct *mm)
  16 {
  17         pgd_t *new_pgd, *init_pgd;
  18         int i;
  19
  20         new_pgd = (pgd_t *) __get_free_pages(GFP_KERNEL, 0);
  21         if (!new_pgd)
  22                 return NULL;
  23         for (i = 0; i < PTRS_PER_PGD; i++) {
  24                 (*new_pgd) = 1;
  25                 new_pgd++;
  26         }
  27         new_pgd -= PTRS_PER_PGD;
  28
  29         init_pgd = pgd_offset_k(0);
  30
  31         memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
  32                (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
  33
  34         cpu_dcache_wb_range((unsigned long)new_pgd,
  35                             (unsigned long)new_pgd +
  36                             PTRS_PER_PGD * sizeof(pgd_t));
  37         inc_lruvec_page_state(virt_to_page((unsigned long *)new_pgd),
  38                               NR_PAGETABLE);
  39
  40         return new_pgd;
  41 }
  42
  43 void pgd_free(struct mm_struct *mm, pgd_t * pgd)
  44 {
  45         pmd_t *pmd;
  46         struct page *pte;
  47
  48         if (!pgd)
  49                 return;
  50
  51         pmd = (pmd_t *) pgd;
  52         if (pmd_none(*pmd))
  53                 goto free;
  54         if (pmd_bad(*pmd)) {
  55                 pmd_ERROR(*pmd);
  56                 pmd_clear(pmd);
  57                 goto free;
  58         }
  59
  60         pte = pmd_page(*pmd);
  61         pmd_clear(pmd);
  62         dec_lruvec_page_state(virt_to_page((unsigned long *)pgd), NR_PAGETABLE);
  63         pte_free(mm, pte);
  64         mm_dec_nr_ptes(mm);
  65         pmd_free(mm, pmd);
  66 free:
  67         free_pages((unsigned long)pgd, 0);
  68 }
  69
  70 /*
  71  * In order to soft-boot, we need to insert a 1:1 mapping in place of
  72  * the user-mode pages.  This will then ensure that we have predictable
  73  * results when turning the mmu off
  74  */
  75 void setup_mm_for_reboot(char mode)
  76 {
  77         unsigned long pmdval;
  78         pgd_t *pgd;
  79         p4d_t *p4d;
  80         pud_t *pud;
  81         pmd_t *pmd;
  82         int i;
  83
  84         if (current->mm && current->mm->pgd)
  85                 pgd = current->mm->pgd;
  86         else
  87                 pgd = init_mm.pgd;
  88
  89         for (i = 0; i < USER_PTRS_PER_PGD; i++) {
  90                 pmdval = (i << PGDIR_SHIFT);
  91                 p4d = p4d_offset(pgd, i << PGDIR_SHIFT);
  92                 pud = pud_offset(p4d, i << PGDIR_SHIFT);
  93                 pmd = pmd_offset(pud + i, i << PGDIR_SHIFT);
  94                 set_pmd(pmd, __pmd(pmdval));
  95         }
  96 }