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/*
* Suspend support specific for i386 - temporary page tables
*
* Distribute under GPLv2
*
* Copyright (c) 2006 Rafael J. Wysocki <rjw@sisk.pl>
*/
#include <linux/suspend.h>
#include <linux/bootmem.h>
#include <asm/system.h>
#include <asm/page.h>
#include <asm/pgtable.h>
/* Defined in arch/i386/power/swsusp.S */
extern int restore_image(void);
/* References to section boundaries */
extern const void __nosave_begin, __nosave_end;
/* Pointer to the temporary resume page tables */
pgd_t *resume_pg_dir;
/* The following three functions are based on the analogous code in
* arch/i386/mm/init.c
*/
/*
* Create a middle page table on a resume-safe page and put a pointer to it in
* the given global directory entry. This only returns the gd entry
* in non-PAE compilation mode, since the middle layer is folded.
*/
static pmd_t *resume_one_md_table_init(pgd_t *pgd)
{
pud_t *pud;
pmd_t *pmd_table;
#ifdef CONFIG_X86_PAE
pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
if (!pmd_table)
return NULL;
set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
pud = pud_offset(pgd, 0);
BUG_ON(pmd_table != pmd_offset(pud, 0));
#else
pud = pud_offset(pgd, 0);
pmd_table = pmd_offset(pud, 0);
#endif
return pmd_table;
}
/*
* Create a page table on a resume-safe page and place a pointer to it in
* a middle page directory entry.
*/
static pte_t *resume_one_page_table_init(pmd_t *pmd)
{
if (pmd_none(*pmd)) {
pte_t *page_table = (pte_t *)get_safe_page(GFP_ATOMIC);
if (!page_table)
return NULL;
set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
BUG_ON(page_table != pte_offset_kernel(pmd, 0));
return page_table;
}
return pte_offset_kernel(pmd, 0);
}
/*
* This maps the physical memory to kernel virtual address space, a total
* of max_low_pfn pages, by creating page tables starting from address
* PAGE_OFFSET. The page tables are allocated out of resume-safe pages.
*/
static int resume_physical_mapping_init(pgd_t *pgd_base)
{
unsigned long pfn;
pgd_t *pgd;
pmd_t *pmd;
pte_t *pte;
int pgd_idx, pmd_idx;
pgd_idx = pgd_index(PAGE_OFFSET);
pgd = pgd_base + pgd_idx;
pfn = 0;
for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
pmd = resume_one_md_table_init(pgd);
if (!pmd)
return -ENOMEM;
if (pfn >= max_low_pfn)
continue;
for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD; pmd++, pmd_idx++) {
if (pfn >= max_low_pfn)
break;
/* Map with big pages if possible, otherwise create
* normal page tables.
* NOTE: We can mark everything as executable here
*/
if (cpu_has_pse) {
set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
pfn += PTRS_PER_PTE;
} else {
pte_t *max_pte;
pte = resume_one_page_table_init(pmd);
if (!pte)
return -ENOMEM;
max_pte = pte + PTRS_PER_PTE;
for (; pte < max_pte; pte++, pfn++) {
if (pfn >= max_low_pfn)
break;
set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
}
}
}
}
return 0;
}
static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
{
#ifdef CONFIG_X86_PAE
int i;
/* Init entries of the first-level page table to the zero page */
for (i = 0; i < PTRS_PER_PGD; i++)
set_pgd(pg_dir + i,
__pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
#endif
}
int swsusp_arch_resume(void)
{
int error;
resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
if (!resume_pg_dir)
return -ENOMEM;
resume_init_first_level_page_table(resume_pg_dir);
error = resume_physical_mapping_init(resume_pg_dir);
if (error)
return error;
/* We have got enough memory and from now on we cannot recover */
restore_image();
return 0;
}
/*
* pfn_is_nosave - check if given pfn is in the 'nosave' section
*/
int pfn_is_nosave(unsigned long pfn)
{
unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
}
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