1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Hibernation support specific for i386 - temporary page tables
4 *
5 * Copyright (c) 2006 Rafael J. Wysocki <rjw@sisk.pl>
6 */
7
8 #include <linux/gfp.h>
9 #include <linux/suspend.h>
10 #include <linux/memblock.h>
11 #include <linux/pgtable.h>
12
13 #include <asm/page.h>
14 #include <asm/mmzone.h>
15 #include <asm/sections.h>
16 #include <asm/suspend.h>
17
18 /* Pointer to the temporary resume page tables */
19 pgd_t *resume_pg_dir;
20
21 /* The following three functions are based on the analogous code in
22 * arch/x86/mm/init_32.c
23 */
24
25 /*
26 * Create a middle page table on a resume-safe page and put a pointer to it in
27 * the given global directory entry. This only returns the gd entry
28 * in non-PAE compilation mode, since the middle layer is folded.
29 */
30 static pmd_t *resume_one_md_table_init(pgd_t *pgd)
31 {
32 p4d_t *p4d;
33 pud_t *pud;
34 pmd_t *pmd_table;
35
36 #ifdef CONFIG_X86_PAE
37 pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
38 if (!pmd_table)
39 return NULL;
40
41 set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
42 p4d = p4d_offset(pgd, 0);
43 pud = pud_offset(p4d, 0);
44
45 BUG_ON(pmd_table != pmd_offset(pud, 0));
46 #else
47 p4d = p4d_offset(pgd, 0);
48 pud = pud_offset(p4d, 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 */
59 static 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 */
81 static 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 (boot_cpu_has(X86_FEATURE_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
133 static 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
145 static int set_up_temporary_text_mapping(pgd_t *pgd_base)
146 {
147 pgd_t *pgd;
148 pmd_t *pmd;
149 pte_t *pte;
150
151 pgd = pgd_base + pgd_index(restore_jump_address);
152
153 pmd = resume_one_md_table_init(pgd);
154 if (!pmd)
155 return -ENOMEM;
156
157 if (boot_cpu_has(X86_FEATURE_PSE)) {
158 set_pmd(pmd + pmd_index(restore_jump_address),
159 __pmd((jump_address_phys & PMD_MASK) | pgprot_val(PAGE_KERNEL_LARGE_EXEC)));
160 } else {
161 pte = resume_one_page_table_init(pmd);
162 if (!pte)
163 return -ENOMEM;
164 set_pte(pte + pte_index(restore_jump_address),
165 __pte((jump_address_phys & PAGE_MASK) | pgprot_val(PAGE_KERNEL_EXEC)));
166 }
167
168 return 0;
169 }
170
171 asmlinkage int swsusp_arch_resume(void)
172 {
173 int error;
174
175 resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
176 if (!resume_pg_dir)
177 return -ENOMEM;
178
179 resume_init_first_level_page_table(resume_pg_dir);
180
181 error = set_up_temporary_text_mapping(resume_pg_dir);
182 if (error)
183 return error;
184
185 error = resume_physical_mapping_init(resume_pg_dir);
186 if (error)
187 return error;
188
189 temp_pgt = __pa(resume_pg_dir);
190
191 error = relocate_restore_code();
192 if (error)
193 return error;
194
195 /* We have got enough memory and from now on we cannot recover */
196 restore_image();
197 return 0;
198 }
199
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