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  */
resume_one_md_table_init(pgd_t * pgd)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  */
resume_one_page_table_init(pmd_t * pmd)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  */
resume_physical_mapping_init(pgd_t * pgd_base)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 
resume_init_first_level_page_table(pgd_t * pg_dir)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 
set_up_temporary_text_mapping(pgd_t * pgd_base)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 
swsusp_arch_resume(void)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