x86/power/hibernate_32.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Hibernation support specific for i386 - temporary page tables
0004  *
0005  * Copyright (c) 2006 Rafael J. Wysocki <rjw@sisk.pl>
0006  */
0007
0008 #include <linux/gfp.h>
0009 #include <linux/suspend.h>
0010 #include <linux/memblock.h>
0011 #include <linux/pgtable.h>
0012
0013 #include <asm/page.h>
0014 #include <asm/mmzone.h>
0015 #include <asm/sections.h>
0016 #include <asm/suspend.h>
0017
0018 /* Pointer to the temporary resume page tables */
0019 pgd_t *resume_pg_dir;
0020
0021 /* The following three functions are based on the analogous code in
0022  * arch/x86/mm/init_32.c
0023  */
0024
0025 /*
0026  * Create a middle page table on a resume-safe page and put a pointer to it in
0027  * the given global directory entry.  This only returns the gd entry
0028  * in non-PAE compilation mode, since the middle layer is folded.
0029  */
0030 static pmd_t *resume_one_md_table_init(pgd_t *pgd)
0031 {
0032     p4d_t *p4d;
0033     pud_t *pud;
0034     pmd_t *pmd_table;
0035
0036 #ifdef CONFIG_X86_PAE
0037     pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
0038     if (!pmd_table)
0039         return NULL;
0040
0041     set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
0042     p4d = p4d_offset(pgd, 0);
0043     pud = pud_offset(p4d, 0);
0044
0045     BUG_ON(pmd_table != pmd_offset(pud, 0));
0046 #else
0047     p4d = p4d_offset(pgd, 0);
0048     pud = pud_offset(p4d, 0);
0049     pmd_table = pmd_offset(pud, 0);
0050 #endif
0051
0052     return pmd_table;
0053 }
0054
0055 /*
0056  * Create a page table on a resume-safe page and place a pointer to it in
0057  * a middle page directory entry.
0058  */
0059 static pte_t *resume_one_page_table_init(pmd_t *pmd)
0060 {
0061     if (pmd_none(*pmd)) {
0062         pte_t *page_table = (pte_t *)get_safe_page(GFP_ATOMIC);
0063         if (!page_table)
0064             return NULL;
0065
0066         set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
0067
0068         BUG_ON(page_table != pte_offset_kernel(pmd, 0));
0069
0070         return page_table;
0071     }
0072
0073     return pte_offset_kernel(pmd, 0);
0074 }
0075
0076 /*
0077  * This maps the physical memory to kernel virtual address space, a total
0078  * of max_low_pfn pages, by creating page tables starting from address
0079  * PAGE_OFFSET.  The page tables are allocated out of resume-safe pages.
0080  */
0081 static int resume_physical_mapping_init(pgd_t *pgd_base)
0082 {
0083     unsigned long pfn;
0084     pgd_t *pgd;
0085     pmd_t *pmd;
0086     pte_t *pte;
0087     int pgd_idx, pmd_idx;
0088
0089     pgd_idx = pgd_index(PAGE_OFFSET);
0090     pgd = pgd_base + pgd_idx;
0091     pfn = 0;
0092
0093     for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
0094         pmd = resume_one_md_table_init(pgd);
0095         if (!pmd)
0096             return -ENOMEM;
0097
0098         if (pfn >= max_low_pfn)
0099             continue;
0100
0101         for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD; pmd++, pmd_idx++) {
0102             if (pfn >= max_low_pfn)
0103                 break;
0104
0105             /* Map with big pages if possible, otherwise create
0106              * normal page tables.
0107              * NOTE: We can mark everything as executable here
0108              */
0109             if (boot_cpu_has(X86_FEATURE_PSE)) {
0110                 set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
0111                 pfn += PTRS_PER_PTE;
0112             } else {
0113                 pte_t *max_pte;
0114
0115                 pte = resume_one_page_table_init(pmd);
0116                 if (!pte)
0117                     return -ENOMEM;
0118
0119                 max_pte = pte + PTRS_PER_PTE;
0120                 for (; pte < max_pte; pte++, pfn++) {
0121                     if (pfn >= max_low_pfn)
0122                         break;
0123
0124                     set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
0125                 }
0126             }
0127         }
0128     }
0129
0130     return 0;
0131 }
0132
0133 static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
0134 {
0135 #ifdef CONFIG_X86_PAE
0136     int i;
0137
0138     /* Init entries of the first-level page table to the zero page */
0139     for (i = 0; i < PTRS_PER_PGD; i++)
0140         set_pgd(pg_dir + i,
0141             __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
0142 #endif
0143 }
0144
0145 static int set_up_temporary_text_mapping(pgd_t *pgd_base)
0146 {
0147     pgd_t *pgd;
0148     pmd_t *pmd;
0149     pte_t *pte;
0150
0151     pgd = pgd_base + pgd_index(restore_jump_address);
0152
0153     pmd = resume_one_md_table_init(pgd);
0154     if (!pmd)
0155         return -ENOMEM;
0156
0157     if (boot_cpu_has(X86_FEATURE_PSE)) {
0158         set_pmd(pmd + pmd_index(restore_jump_address),
0159         __pmd((jump_address_phys & PMD_MASK) | pgprot_val(PAGE_KERNEL_LARGE_EXEC)));
0160     } else {
0161         pte = resume_one_page_table_init(pmd);
0162         if (!pte)
0163             return -ENOMEM;
0164         set_pte(pte + pte_index(restore_jump_address),
0165         __pte((jump_address_phys & PAGE_MASK) | pgprot_val(PAGE_KERNEL_EXEC)));
0166     }
0167
0168     return 0;
0169 }
0170
0171 asmlinkage int swsusp_arch_resume(void)
0172 {
0173     int error;
0174
0175     resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
0176     if (!resume_pg_dir)
0177         return -ENOMEM;
0178
0179     resume_init_first_level_page_table(resume_pg_dir);
0180
0181     error = set_up_temporary_text_mapping(resume_pg_dir);
0182     if (error)
0183         return error;
0184
0185     error = resume_physical_mapping_init(resume_pg_dir);
0186     if (error)
0187         return error;
0188
0189     temp_pgt = __pa(resume_pg_dir);
0190
0191     error = relocate_restore_code();
0192     if (error)
0193         return error;
0194
0195     /* We have got enough memory and from now on we cannot recover */
0196     restore_image();
0197     return 0;
0198 }