arch/x86/power/hibernate_32.c

   1 /*
   2  * Hibernation 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/gfp.h>
  10 #include <linux/suspend.h>
  11 #include <linux/bootmem.h>
  12
  13 #include <asm/page.h>
  14 #include <asm/pgtable.h>
  15 #include <asm/mmzone.h>
  16
  17 /* Defined in hibernate_asm_32.S */
  18 extern int restore_image(void);
  19
  20 /* References to section boundaries */
  21 extern const void __nosave_begin, __nosave_end;
  22
  23 /* Pointer to the temporary resume page tables */
  24 pgd_t *resume_pg_dir;
  25
  26 /* The following three functions are based on the analogous code in
  27  * arch/x86/mm/init_32.c
  28  */
  29
  30 /*
  31  * Create a middle page table on a resume-safe page and put a pointer to it in
  32  * the given global directory entry.  This only returns the gd entry
  33  * in non-PAE compilation mode, since the middle layer is folded.
  34  */
  35 static pmd_t *resume_one_md_table_init(pgd_t *pgd)
  36 {
  37         pud_t *pud;
  38         pmd_t *pmd_table;
  39
  40 #ifdef CONFIG_X86_PAE
  41         pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
  42         if (!pmd_table)
  43                 return NULL;
  44
  45         set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
  46         pud = pud_offset(pgd, 0);
  47
  48         BUG_ON(pmd_table != pmd_offset(pud, 0));
  49 #else
  50         pud = pud_offset(pgd, 0);
  51         pmd_table = pmd_offset(pud, 0);
  52 #endif
  53
  54         return pmd_table;
  55 }
  56
  57 /*
  58  * Create a page table on a resume-safe page and place a pointer to it in
  59  * a middle page directory entry.
  60  */
  61 static pte_t *resume_one_page_table_init(pmd_t *pmd)
  62 {
  63         if (pmd_none(*pmd)) {
  64                 pte_t *page_table = (pte_t *)get_safe_page(GFP_ATOMIC);
  65                 if (!page_table)
  66                         return NULL;
  67
  68                 set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
  69
  70                 BUG_ON(page_table != pte_offset_kernel(pmd, 0));
  71
  72                 return page_table;
  73         }
  74
  75         return pte_offset_kernel(pmd, 0);
  76 }
  77
  78 /*
  79  * This maps the physical memory to kernel virtual address space, a total
  80  * of max_low_pfn pages, by creating page tables starting from address
  81  * PAGE_OFFSET.  The page tables are allocated out of resume-safe pages.
  82  */
  83 static int resume_physical_mapping_init(pgd_t *pgd_base)
  84 {
  85         unsigned long pfn;
  86         pgd_t *pgd;
  87         pmd_t *pmd;
  88         pte_t *pte;
  89         int pgd_idx, pmd_idx;
  90
  91         pgd_idx = pgd_index(PAGE_OFFSET);
  92         pgd = pgd_base + pgd_idx;
  93         pfn = 0;
  94
  95         for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
  96                 pmd = resume_one_md_table_init(pgd);
  97                 if (!pmd)
  98                         return -ENOMEM;
  99
 100                 if (pfn >= max_low_pfn)
 101                         continue;
 102
 103                 for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD; pmd++, pmd_idx++) {
 104                         if (pfn >= max_low_pfn)
 105                                 break;
 106
 107                         /* Map with big pages if possible, otherwise create
 108                          * normal page tables.
 109                          * NOTE: We can mark everything as executable here
 110                          */
 111                         if (cpu_has_pse) {
 112                                 set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
 113                                 pfn += PTRS_PER_PTE;
 114                         } else {
 115                                 pte_t *max_pte;
 116
 117                                 pte = resume_one_page_table_init(pmd);
 118                                 if (!pte)
 119                                         return -ENOMEM;
 120
 121                                 max_pte = pte + PTRS_PER_PTE;
 122                                 for (; pte < max_pte; pte++, pfn++) {
 123                                         if (pfn >= max_low_pfn)
 124                                                 break;
 125
 126                                         set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
 127                                 }
 128                         }
 129                 }
 130         }
 131
 132         return 0;
 133 }
 134
 135 static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
 136 {
 137 #ifdef CONFIG_X86_PAE
 138         int i;
 139
 140         /* Init entries of the first-level page table to the zero page */
 141         for (i = 0; i < PTRS_PER_PGD; i++)
 142                 set_pgd(pg_dir + i,
 143                         __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
 144 #endif
 145 }
 146
 147 int swsusp_arch_resume(void)
 148 {
 149         int error;
 150
 151         resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
 152         if (!resume_pg_dir)
 153                 return -ENOMEM;
 154
 155         resume_init_first_level_page_table(resume_pg_dir);
 156         error = resume_physical_mapping_init(resume_pg_dir);
 157         if (error)
 158                 return error;
 159
 160         /* We have got enough memory and from now on we cannot recover */
 161         restore_image();
 162         return 0;
 163 }
 164
 165 /*
 166  *      pfn_is_nosave - check if given pfn is in the 'nosave' section
 167  */
 168
 169 int pfn_is_nosave(unsigned long pfn)
 170 {
 171         unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
 172         unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
 173         return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
 174 }