linux/arch/nds32/mm/mm-nds32.c
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   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
  15pgd_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
  43void 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);
  66free:
  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 */
  75void 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}
  97
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