arch/x86/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 /* References to section boundaries */
  20 extern const void __nosave_begin, __nosave_end;
  21
  22 /* Pointer to the temporary resume page tables */
  23 pgd_t *resume_pg_dir;
  24
  25 /* The following three functions are based on the analogous code in
  26  * arch/i386/mm/init.c
  27  */
  28
  29 /*
  30  * Create a middle page table on a resume-safe page and put a pointer to it in
  31  * the given global directory entry.  This only returns the gd entry
  32  * in non-PAE compilation mode, since the middle layer is folded.
  33  */
  34 static pmd_t *resume_one_md_table_init(pgd_t *pgd)
  35 {
  36         pud_t *pud;
  37         pmd_t *pmd_table;
  38
  39 #ifdef CONFIG_X86_PAE
  40         pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
  41         if (!pmd_table)
  42                 return NULL;
  43
  44         set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
  45         pud = pud_offset(pgd, 0);
  46
  47         BUG_ON(pmd_table != pmd_offset(pud, 0));
  48 #else
  49         pud = pud_offset(pgd, 0);
  50         pmd_table = pmd_offset(pud, 0);
  51 #endif
  52
  53         return pmd_table;
  54 }
  55
  56 /*
  57  * Create a page table on a resume-safe page and place a pointer to it in
  58  * a middle page directory entry.
  59  */
  60 static pte_t *resume_one_page_table_init(pmd_t *pmd)
  61 {
  62         if (pmd_none(*pmd)) {
  63                 pte_t *page_table = (pte_t *)get_safe_page(GFP_ATOMIC);
  64                 if (!page_table)
  65                         return NULL;
  66
  67                 set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
  68
  69                 BUG_ON(page_table != pte_offset_kernel(pmd, 0));
  70
  71                 return page_table;
  72         }
  73
  74         return pte_offset_kernel(pmd, 0);
  75 }
  76
  77 /*
  78  * This maps the physical memory to kernel virtual address space, a total
  79  * of max_low_pfn pages, by creating page tables starting from address
  80  * PAGE_OFFSET.  The page tables are allocated out of resume-safe pages.
  81  */
  82 static int resume_physical_mapping_init(pgd_t *pgd_base)
  83 {
  84         unsigned long pfn;
  85         pgd_t *pgd;
  86         pmd_t *pmd;
  87         pte_t *pte;
  88         int pgd_idx, pmd_idx;
  89
  90         pgd_idx = pgd_index(PAGE_OFFSET);
  91         pgd = pgd_base + pgd_idx;
  92         pfn = 0;
  93
  94         for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
  95                 pmd = resume_one_md_table_init(pgd);
  96                 if (!pmd)
  97                         return -ENOMEM;
  98
  99                 if (pfn >= max_low_pfn)
 100                         continue;
 101
 102                 for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD; pmd++, pmd_idx++) {
 103                         if (pfn >= max_low_pfn)
 104                                 break;
 105
 106                         /* Map with big pages if possible, otherwise create
 107                          * normal page tables.
 108                          * NOTE: We can mark everything as executable here
 109                          */
 110                         if (cpu_has_pse) {
 111                                 set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
 112                                 pfn += PTRS_PER_PTE;
 113                         } else {
 114                                 pte_t *max_pte;
 115
 116                                 pte = resume_one_page_table_init(pmd);
 117                                 if (!pte)
 118                                         return -ENOMEM;
 119
 120                                 max_pte = pte + PTRS_PER_PTE;
 121                                 for (; pte < max_pte; pte++, pfn++) {
 122                                         if (pfn >= max_low_pfn)
 123                                                 break;
 124
 125                                         set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
 126                                 }
 127                         }
 128                 }
 129         }
 130         return 0;
 131 }
 132
 133 static 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
 145 int swsusp_arch_resume(void)
 146 {
 147         int error;
 148
 149         resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
 150         if (!resume_pg_dir)
 151                 return -ENOMEM;
 152
 153         resume_init_first_level_page_table(resume_pg_dir);
 154         error = resume_physical_mapping_init(resume_pg_dir);
 155         if (error)
 156                 return error;
 157
 158         /* We have got enough memory and from now on we cannot recover */
 159         restore_image();
 160         return 0;
 161 }
 162
 163 /*
 164  *      pfn_is_nosave - check if given pfn is in the 'nosave' section
 165  */
 166
 167 int pfn_is_nosave(unsigned long pfn)
 168 {
 169         unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
 170         unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
 171         return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
 172 }