arch/i386/power/suspend.c

   1 /*
   2  * Suspend support specific for i386 - temporary page tables
   3  *
   4  * Distribute under GPLv2
   5  *
   6  * Copyright (c) 2006 Rafael J. Wysocki <rjw@sisk.pl>
   7  */
   8
   9 #include <linux/suspend.h>
  10 #include <linux/bootmem.h>
  11
  12 #include <asm/system.h>
  13 #include <asm/page.h>
  14 #include <asm/pgtable.h>
  15
  16 /* Defined in arch/i386/power/swsusp.S */
  17 extern int restore_image(void);
  18
  19 /* Pointer to the temporary resume page tables */
  20 pgd_t *resume_pg_dir;
  21
  22 /* The following three functions are based on the analogous code in
  23  * arch/i386/mm/init.c
  24  */
  25
  26 /*
  27  * Create a middle page table on a resume-safe page and put a pointer to it in
  28  * the given global directory entry.  This only returns the gd entry
  29  * in non-PAE compilation mode, since the middle layer is folded.
  30  */
  31 static pmd_t *resume_one_md_table_init(pgd_t *pgd)
  32 {
  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         pud = pud_offset(pgd, 0);
  43
  44         BUG_ON(pmd_table != pmd_offset(pud, 0));
  45 #else
  46         pud = pud_offset(pgd, 0);
  47         pmd_table = pmd_offset(pud, 0);
  48 #endif
  49
  50         return pmd_table;
  51 }
  52
  53 /*
  54  * Create a page table on a resume-safe page and place a pointer to it in
  55  * a middle page directory entry.
  56  */
  57 static pte_t *resume_one_page_table_init(pmd_t *pmd)
  58 {
  59         if (pmd_none(*pmd)) {
  60                 pte_t *page_table = (pte_t *)get_safe_page(GFP_ATOMIC);
  61                 if (!page_table)
  62                         return NULL;
  63
  64                 set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
  65
  66                 BUG_ON(page_table != pte_offset_kernel(pmd, 0));
  67
  68                 return page_table;
  69         }
  70
  71         return pte_offset_kernel(pmd, 0);
  72 }
  73
  74 /*
  75  * This maps the physical memory to kernel virtual address space, a total
  76  * of max_low_pfn pages, by creating page tables starting from address
  77  * PAGE_OFFSET.  The page tables are allocated out of resume-safe pages.
  78  */
  79 static int resume_physical_mapping_init(pgd_t *pgd_base)
  80 {
  81         unsigned long pfn;
  82         pgd_t *pgd;
  83         pmd_t *pmd;
  84         pte_t *pte;
  85         int pgd_idx, pmd_idx;
  86
  87         pgd_idx = pgd_index(PAGE_OFFSET);
  88         pgd = pgd_base + pgd_idx;
  89         pfn = 0;
  90
  91         for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
  92                 pmd = resume_one_md_table_init(pgd);
  93                 if (!pmd)
  94                         return -ENOMEM;
  95
  96                 if (pfn >= max_low_pfn)
  97                         continue;
  98
  99                 for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD; pmd++, pmd_idx++) {
 100                         if (pfn >= max_low_pfn)
 101                                 break;
 102
 103                         /* Map with big pages if possible, otherwise create
 104                          * normal page tables.
 105                          * NOTE: We can mark everything as executable here
 106                          */
 107                         if (cpu_has_pse) {
 108                                 set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
 109                                 pfn += PTRS_PER_PTE;
 110                         } else {
 111                                 pte_t *max_pte;
 112
 113                                 pte = resume_one_page_table_init(pmd);
 114                                 if (!pte)
 115                                         return -ENOMEM;
 116
 117                                 max_pte = pte + PTRS_PER_PTE;
 118                                 for (; pte < max_pte; pte++, pfn++) {
 119                                         if (pfn >= max_low_pfn)
 120                                                 break;
 121
 122                                         set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
 123                                 }
 124                         }
 125                 }
 126         }
 127         return 0;
 128 }
 129
 130 static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
 131 {
 132 #ifdef CONFIG_X86_PAE
 133         int i;
 134
 135         /* Init entries of the first-level page table to the zero page */
 136         for (i = 0; i < PTRS_PER_PGD; i++)
 137                 set_pgd(pg_dir + i,
 138                         __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
 139 #endif
 140 }
 141
 142 int swsusp_arch_resume(void)
 143 {
 144         int error;
 145
 146         resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
 147         if (!resume_pg_dir)
 148                 return -ENOMEM;
 149
 150         resume_init_first_level_page_table(resume_pg_dir);
 151         error = resume_physical_mapping_init(resume_pg_dir);
 152         if (error)
 153                 return error;
 154
 155         /* We have got enough memory and from now on we cannot recover */
 156         restore_image();
 157         return 0;
 158 }