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