tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * linux/arch/arm/mm/pgd.c
3 *
4 * Copyright (C) 1998-2005 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10#include <linux/mm.h>
11#include <linux/gfp.h>
12#include <linux/highmem.h>
13
14#include <asm/pgalloc.h>
15#include <asm/page.h>
16#include <asm/tlbflush.h>
17
18#include "mm.h"
19
20/*
21 * need to get a 16k page for level 1
22 */
23pgd_t *pgd_alloc(struct mm_struct *mm)
24{
25 pgd_t *new_pgd, *init_pgd;
26 pud_t *new_pud, *init_pud;
27 pmd_t *new_pmd, *init_pmd;
28 pte_t *new_pte, *init_pte;
29
30 new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 2);
31 if (!new_pgd)
32 goto no_pgd;
33
34 memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
35
36 /*
37 * Copy over the kernel and IO PGD entries
38 */
39 init_pgd = pgd_offset_k(0);
40 memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
41 (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
42
43 clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
44
45 if (!vectors_high()) {
46 /*
47 * On ARM, first page must always be allocated since it
48 * contains the machine vectors.
49 */
50 new_pud = pud_alloc(mm, new_pgd, 0);
51 if (!new_pud)
52 goto no_pud;
53
54 new_pmd = pmd_alloc(mm, new_pud, 0);
55 if (!new_pmd)
56 goto no_pmd;
57
58 new_pte = pte_alloc_map(mm, NULL, new_pmd, 0);
59 if (!new_pte)
60 goto no_pte;
61
62 init_pud = pud_offset(init_pgd, 0);
63 init_pmd = pmd_offset(init_pud, 0);
64 init_pte = pte_offset_map(init_pmd, 0);
65 set_pte_ext(new_pte, *init_pte, 0);
66 pte_unmap(init_pte);
67 pte_unmap(new_pte);
68 }
69
70 return new_pgd;
71
72no_pte:
73 pmd_free(mm, new_pmd);
74no_pmd:
75 pud_free(mm, new_pud);
76no_pud:
77 free_pages((unsigned long)new_pgd, 2);
78no_pgd:
79 return NULL;
80}
81
82void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
83{
84 pgd_t *pgd;
85 pud_t *pud;
86 pmd_t *pmd;
87 pgtable_t pte;
88
89 if (!pgd_base)
90 return;
91
92 pgd = pgd_base + pgd_index(0);
93 if (pgd_none_or_clear_bad(pgd))
94 goto no_pgd;
95
96 pud = pud_offset(pgd, 0);
97 if (pud_none_or_clear_bad(pud))
98 goto no_pud;
99
100 pmd = pmd_offset(pud, 0);
101 if (pmd_none_or_clear_bad(pmd))
102 goto no_pmd;
103
104 pte = pmd_pgtable(*pmd);
105 pmd_clear(pmd);
106 pte_free(mm, pte);
107no_pmd:
108 pud_clear(pud);
109 pmd_free(mm, pmd);
110no_pud:
111 pgd_clear(pgd);
112 pud_free(mm, pud);
113no_pgd:
114 free_pages((unsigned long) pgd_base, 2);
115}