LXR linux/arch/x86/power/hibernate

   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 */
  19extern int restore_image(void);
  20
  21/* Pointer to the temporary resume page tables */
  22pgd_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 */
  33static pmd_t *resume_one_md_table_init(pgd_t *pgd)
  34{
  35        pud_t *pud;
  36        pmd_t *pmd_table;
  37
  38#ifdef CONFIG_X86_PAE
  39        pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
  40        if (!pmd_table)
  41                return NULL;
  42
  43        set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
  44        pud = pud_offset(pgd, 0);
  45
  46        BUG_ON(pmd_table != pmd_offset(pud, 0));
  47#else
  48        pud = pud_offset(pgd, 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 (cpu_has_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
 145int 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
 167int 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}
 173