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
  17/* Defined in hibernate_asm_32.S */
  18extern int restore_image(void);
  19
  20/* References to section boundaries */
  21extern const void __nosave_begin, __nosave_end;
  22
  23/* Pointer to the temporary resume page tables */
  24pgd_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 */
  35static 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 */
  61static 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 */
  83static 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
 135static 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
 147int 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
 169int 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}
 175