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/highmem.h>
12
13#include <asm/pgalloc.h>
14#include <asm/page.h>
15#include <asm/tlbflush.h>
16
17#include "mm.h"
18
19#define FIRST_KERNEL_PGD_NR	(FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
20
21/*
22 * need to get a 16k page for level 1
23 */
24pgd_t *get_pgd_slow(struct mm_struct *mm)
25{
26	pgd_t *new_pgd, *init_pgd;
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	memzero(new_pgd, FIRST_KERNEL_PGD_NR * 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 + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
41		       (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * 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_pmd = pmd_alloc(mm, new_pgd, 0);
51		if (!new_pmd)
52			goto no_pmd;
53
54		new_pte = pte_alloc_map(mm, new_pmd, 0);
55		if (!new_pte)
56			goto no_pte;
57
58		init_pmd = pmd_offset(init_pgd, 0);
59		init_pte = pte_offset_map_nested(init_pmd, 0);
60		set_pte_ext(new_pte, *init_pte, 0);
61		pte_unmap_nested(init_pte);
62		pte_unmap(new_pte);
63	}
64
65	return new_pgd;
66
67no_pte:
68	pmd_free(new_pmd);
69no_pmd:
70	free_pages((unsigned long)new_pgd, 2);
71no_pgd:
72	return NULL;
73}
74
75void free_pgd_slow(pgd_t *pgd)
76{
77	pmd_t *pmd;
78	struct page *pte;
79
80	if (!pgd)
81		return;
82
83	/* pgd is always present and good */
84	pmd = pmd_off(pgd, 0);
85	if (pmd_none(*pmd))
86		goto free;
87	if (pmd_bad(*pmd)) {
88		pmd_ERROR(*pmd);
89		pmd_clear(pmd);
90		goto free;
91	}
92
93	pte = pmd_page(*pmd);
94	pmd_clear(pmd);
95	dec_zone_page_state(virt_to_page((unsigned long *)pgd), NR_PAGETABLE);
96	pte_lock_deinit(pte);
97	pte_free(pte);
98	pmd_free(pmd);
99free:
100	free_pages((unsigned long) pgd, 2);
101}
102