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 */
19pgd_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 */
30static 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 */
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 (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
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
145static 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
171asmlinkage 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