1/*
2 * Hibernation support specific for i386 - temporary page tables
3 *
4 * Distribute under GPLv2
5 *
6 * Copyright (c) 2006 Rafael J. Wysocki <rjw@sisk.pl>
7 */
8
9#include <linux/gfp.h>
10#include <linux/suspend.h>
11#include <linux/bootmem.h>
12
13#include <asm/page.h>
14#include <asm/pgtable.h>
15#include <asm/mmzone.h>
16#include <asm/sections.h>
17
18/* Defined in hibernate_asm_32.S */
19extern int restore_image(void);
20
21/* Pointer to the temporary resume page tables */
22pgd_t *resume_pg_dir;
23
24/* The following three functions are based on the analogous code in
25 * arch/x86/mm/init_32.c
26 */
27
28/*
29 * Create a middle page table on a resume-safe page and put a pointer to it in
30 * the given global directory entry.  This only returns the gd entry
31 * in non-PAE compilation mode, since the middle layer is folded.
32 */
33static pmd_t *resume_one_md_table_init(pgd_t *pgd)
34{
35	pud_t *pud;
36	pmd_t *pmd_table;
37
38#ifdef CONFIG_X86_PAE
39	pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
40	if (!pmd_table)
41		return NULL;
42
43	set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
44	pud = pud_offset(pgd, 0);
45
46	BUG_ON(pmd_table != pmd_offset(pud, 0));
47#else
48	pud = pud_offset(pgd, 0);
49	pmd_table = pmd_offset(pud, 0);
50#endif
51
52	return pmd_table;
53}
54
55/*
56 * Create a page table on a resume-safe page and place a pointer to it in
57 * a middle page directory entry.
58 */
59static pte_t *resume_one_page_table_init(pmd_t *pmd)
60{
61	if (pmd_none(*pmd)) {
62		pte_t *page_table = (pte_t *)get_safe_page(GFP_ATOMIC);
63		if (!page_table)
64			return NULL;
65
66		set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
67
68		BUG_ON(page_table != pte_offset_kernel(pmd, 0));
69
70		return page_table;
71	}
72
73	return pte_offset_kernel(pmd, 0);
74}
75
76/*
77 * This maps the physical memory to kernel virtual address space, a total
78 * of max_low_pfn pages, by creating page tables starting from address
79 * PAGE_OFFSET.  The page tables are allocated out of resume-safe pages.
80 */
81static int resume_physical_mapping_init(pgd_t *pgd_base)
82{
83	unsigned long pfn;
84	pgd_t *pgd;
85	pmd_t *pmd;
86	pte_t *pte;
87	int pgd_idx, pmd_idx;
88
89	pgd_idx = pgd_index(PAGE_OFFSET);
90	pgd = pgd_base + pgd_idx;
91	pfn = 0;
92
93	for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
94		pmd = resume_one_md_table_init(pgd);
95		if (!pmd)
96			return -ENOMEM;
97
98		if (pfn >= max_low_pfn)
99			continue;
100
101		for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD; pmd++, pmd_idx++) {
102			if (pfn >= max_low_pfn)
103				break;
104
105			/* Map with big pages if possible, otherwise create
106			 * normal page tables.
107			 * NOTE: We can mark everything as executable here
108			 */
109			if (cpu_has_pse) {
110				set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
111				pfn += PTRS_PER_PTE;
112			} else {
113				pte_t *max_pte;
114
115				pte = resume_one_page_table_init(pmd);
116				if (!pte)
117					return -ENOMEM;
118
119				max_pte = pte + PTRS_PER_PTE;
120				for (; pte < max_pte; pte++, pfn++) {
121					if (pfn >= max_low_pfn)
122						break;
123
124					set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
125				}
126			}
127		}
128	}
129
130	return 0;
131}
132
133static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
134{
135#ifdef CONFIG_X86_PAE
136	int i;
137
138	/* Init entries of the first-level page table to the zero page */
139	for (i = 0; i < PTRS_PER_PGD; i++)
140		set_pgd(pg_dir + i,
141			__pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
142#endif
143}
144
145int swsusp_arch_resume(void)
146{
147	int error;
148
149	resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
150	if (!resume_pg_dir)
151		return -ENOMEM;
152
153	resume_init_first_level_page_table(resume_pg_dir);
154	error = resume_physical_mapping_init(resume_pg_dir);
155	if (error)
156		return error;
157
158	/* We have got enough memory and from now on we cannot recover */
159	restore_image();
160	return 0;
161}
162
163/*
164 *	pfn_is_nosave - check if given pfn is in the 'nosave' section
165 */
166
167int pfn_is_nosave(unsigned long pfn)
168{
169	unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
170	unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
171	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
172}
173