xref: /kernel/linux/linux-5.10/arch/nds32/mm/mm-nds32.c (revision 8c2ecf20) 
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_zone_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_zone_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