hibernate_32.c revision 97a70e548bd97d5a46ae9d44f24aafcc013fd701 
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/suspend.h>
10#include <linux/bootmem.h>
11
12#include <asm/system.h>
13#include <asm/page.h>
14#include <asm/pgtable.h>
15#include <asm/mmzone.h>
16
17/* Defined in hibernate_asm_32.S */
18extern int restore_image(void);
19
20/* References to section boundaries */
21extern const void __nosave_begin, __nosave_end;
22
23/* Pointer to the temporary resume page tables */
24pgd_t *resume_pg_dir;
25
26/* The following three functions are based on the analogous code in
27 * arch/x86/mm/init_32.c
28 */
29
30/*
31 * Create a middle page table on a resume-safe page and put a pointer to it in
32 * the given global directory entry.  This only returns the gd entry
33 * in non-PAE compilation mode, since the middle layer is folded.
34 */
35static pmd_t *resume_one_md_table_init(pgd_t *pgd)
36{
37	pud_t *pud;
38	pmd_t *pmd_table;
39
40#ifdef CONFIG_X86_PAE
41	pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
42	if (!pmd_table)
43		return NULL;
44
45	set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
46	pud = pud_offset(pgd, 0);
47
48	BUG_ON(pmd_table != pmd_offset(pud, 0));
49#else
50	pud = pud_offset(pgd, 0);
51	pmd_table = pmd_offset(pud, 0);
52#endif
53
54	return pmd_table;
55}
56
57/*
58 * Create a page table on a resume-safe page and place a pointer to it in
59 * a middle page directory entry.
60 */
61static pte_t *resume_one_page_table_init(pmd_t *pmd)
62{
63	if (pmd_none(*pmd)) {
64		pte_t *page_table = (pte_t *)get_safe_page(GFP_ATOMIC);
65		if (!page_table)
66			return NULL;
67
68		set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
69
70		BUG_ON(page_table != pte_offset_kernel(pmd, 0));
71
72		return page_table;
73	}
74
75	return pte_offset_kernel(pmd, 0);
76}
77
78/*
79 * This maps the physical memory to kernel virtual address space, a total
80 * of max_low_pfn pages, by creating page tables starting from address
81 * PAGE_OFFSET.  The page tables are allocated out of resume-safe pages.
82 */
83static int resume_physical_mapping_init(pgd_t *pgd_base)
84{
85	unsigned long pfn;
86	pgd_t *pgd;
87	pmd_t *pmd;
88	pte_t *pte;
89	int pgd_idx, pmd_idx;
90
91	pgd_idx = pgd_index(PAGE_OFFSET);
92	pgd = pgd_base + pgd_idx;
93	pfn = 0;
94
95	for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
96		pmd = resume_one_md_table_init(pgd);
97		if (!pmd)
98			return -ENOMEM;
99
100		if (pfn >= max_low_pfn)
101			continue;
102
103		for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD; pmd++, pmd_idx++) {
104			if (pfn >= max_low_pfn)
105				break;
106
107			/* Map with big pages if possible, otherwise create
108			 * normal page tables.
109			 * NOTE: We can mark everything as executable here
110			 */
111			if (cpu_has_pse) {
112				set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
113				pfn += PTRS_PER_PTE;
114			} else {
115				pte_t *max_pte;
116
117				pte = resume_one_page_table_init(pmd);
118				if (!pte)
119					return -ENOMEM;
120
121				max_pte = pte + PTRS_PER_PTE;
122				for (; pte < max_pte; pte++, pfn++) {
123					if (pfn >= max_low_pfn)
124						break;
125
126					set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
127				}
128			}
129		}
130	}
131
132	resume_map_numa_kva(pgd_base);
133
134	return 0;
135}
136
137static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
138{
139#ifdef CONFIG_X86_PAE
140	int i;
141
142	/* Init entries of the first-level page table to the zero page */
143	for (i = 0; i < PTRS_PER_PGD; i++)
144		set_pgd(pg_dir + i,
145			__pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
146#endif
147}
148
149int swsusp_arch_resume(void)
150{
151	int error;
152
153	resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
154	if (!resume_pg_dir)
155		return -ENOMEM;
156
157	resume_init_first_level_page_table(resume_pg_dir);
158	error = resume_physical_mapping_init(resume_pg_dir);
159	if (error)
160		return error;
161
162	/* We have got enough memory and from now on we cannot recover */
163	restore_image();
164	return 0;
165}
166
167/*
168 *	pfn_is_nosave - check if given pfn is in the 'nosave' section
169 */
170
171int pfn_is_nosave(unsigned long pfn)
172{
173	unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
174	unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
175	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
176}
177