/* * Hibernation support specific for i386 - temporary page tables * * Distribute under GPLv2 * * Copyright (c) 2006 Rafael J. Wysocki <rjw@sisk.pl> */ #include <linux/gfp.h> #include <linux/suspend.h> #include <linux/bootmem.h> #include <asm/page.h> #include <asm/pgtable.h> #include <asm/mmzone.h> #include <asm/sections.h> /* Defined in hibernate_asm_32.S */ extern int restore_image(void); /* Pointer to the temporary resume page tables */ pgd_t *resume_pg_dir; /* The following three functions are based on the analogous code in * arch/x86/mm/init_32.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); }