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/memblock.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        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 */
  62static 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 */
  84static 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
 136static 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
 148asmlinkage 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
 170int 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}
 176