linux/arch/x86/power/hibernate_32.c
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   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
  12#include <asm/page.h>
  13#include <asm/pgtable.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