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 #include <asm/sections.h>
  17
  18 /* Defined in hibernate_asm_32.S */
  19 extern int restore_image(void);
  20
  21 /* Pointer to the temporary resume page tables */
  22 pgd_t *resume_pg_dir;
  23
  24 /* The following three functions are based on the analogous code in
  25  * arch/x86/mm/init_32.c
  26  */
  27
  28 /*
  29  * Create a middle page table on a resume-safe page and put a pointer to it in
  30  * the given global directory entry.  This only returns the gd entry
  31  * in non-PAE compilation mode, since the middle layer is folded.
  32  */
  33 static pmd_t *resume_one_md_table_init(pgd_t *pgd)
  34 {
  35         p4d_t *p4d;
  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         p4d = p4d_offset(pgd, 0);
  46         pud = pud_offset(p4d, 0);
  47
  48         BUG_ON(pmd_table != pmd_offset(pud, 0));
  49 #else
  50         p4d = p4d_offset(pgd, 0);
  51         pud = pud_offset(p4d, 0);
  52         pmd_table = pmd_offset(pud, 0);
  53 #endif
  54
  55         return pmd_table;
  56 }
  57
  58 /*
  59  * Create a page table on a resume-safe page and place a pointer to it in
  60  * a middle page directory entry.
  61  */
  62 static pte_t *resume_one_page_table_init(pmd_t *pmd)
  63 {
  64         if (pmd_none(*pmd)) {
  65                 pte_t *page_table = (pte_t *)get_safe_page(GFP_ATOMIC);
  66                 if (!page_table)
  67                         return NULL;
  68
  69                 set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
  70
  71                 BUG_ON(page_table != pte_offset_kernel(pmd, 0));
  72
  73                 return page_table;
  74         }
  75
  76         return pte_offset_kernel(pmd, 0);
  77 }
  78
  79 /*
  80  * This maps the physical memory to kernel virtual address space, a total
  81  * of max_low_pfn pages, by creating page tables starting from address
  82  * PAGE_OFFSET.  The page tables are allocated out of resume-safe pages.
  83  */
  84 static int resume_physical_mapping_init(pgd_t *pgd_base)
  85 {
  86         unsigned long pfn;
  87         pgd_t *pgd;
  88         pmd_t *pmd;
  89         pte_t *pte;
  90         int pgd_idx, pmd_idx;
  91
  92         pgd_idx = pgd_index(PAGE_OFFSET);
  93         pgd = pgd_base + pgd_idx;
  94         pfn = 0;
  95
  96         for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
  97                 pmd = resume_one_md_table_init(pgd);
  98                 if (!pmd)
  99                         return -ENOMEM;
 100
 101                 if (pfn >= max_low_pfn)
 102                         continue;
 103
 104                 for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD; pmd++, pmd_idx++) {
 105                         if (pfn >= max_low_pfn)
 106                                 break;
 107
 108                         /* Map with big pages if possible, otherwise create
 109                          * normal page tables.
 110                          * NOTE: We can mark everything as executable here
 111                          */
 112                         if (boot_cpu_has(X86_FEATURE_PSE)) {
 113                                 set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
 114                                 pfn += PTRS_PER_PTE;
 115                         } else {
 116                                 pte_t *max_pte;
 117
 118                                 pte = resume_one_page_table_init(pmd);
 119                                 if (!pte)
 120                                         return -ENOMEM;
 121
 122                                 max_pte = pte + PTRS_PER_PTE;
 123                                 for (; pte < max_pte; pte++, pfn++) {
 124                                         if (pfn >= max_low_pfn)
 125                                                 break;
 126
 127                                         set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
 128                                 }
 129                         }
 130                 }
 131         }
 132
 133         return 0;
 134 }
 135
 136 static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
 137 {
 138 #ifdef CONFIG_X86_PAE
 139         int i;
 140
 141         /* Init entries of the first-level page table to the zero page */
 142         for (i = 0; i < PTRS_PER_PGD; i++)
 143                 set_pgd(pg_dir + i,
 144                         __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
 145 #endif
 146 }
 147
 148 int swsusp_arch_resume(void)
 149 {
 150         int error;
 151
 152         resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
 153         if (!resume_pg_dir)
 154                 return -ENOMEM;
 155
 156         resume_init_first_level_page_table(resume_pg_dir);
 157         error = resume_physical_mapping_init(resume_pg_dir);
 158         if (error)
 159                 return error;
 160
 161         /* We have got enough memory and from now on we cannot recover */
 162         restore_image();
 163         return 0;
 164 }
 165
 166 /*
 167  *      pfn_is_nosave - check if given pfn is in the 'nosave' section
 168  */
 169
 170 int pfn_is_nosave(unsigned long pfn)
 171 {
 172         unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
 173         unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
 174         return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
 175 }