Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * 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);

}