path: root/kernel/power/tuxonice_highlevel.c

/*
 * kernel/power/tuxonice_highlevel.c
 */
/** \mainpage TuxOnIce.
 *
 * TuxOnIce provides support for saving and restoring an image of
 * system memory to an arbitrary storage device, either on the local computer,
 * or across some network. The support is entirely OS based, so TuxOnIce
 * works without requiring BIOS, APM or ACPI support. The vast majority of the
 * code is also architecture independant, so it should be very easy to port
 * the code to new architectures. TuxOnIce includes support for SMP, 4G HighMem
 * and preemption. Initramfses and initrds are also supported.
 *
 * TuxOnIce uses a modular design, in which the method of storing the image is
 * completely abstracted from the core code, as are transformations on the data
 * such as compression and/or encryption (multiple 'modules' can be used to
 * provide arbitrary combinations of functionality). The user interface is also
 * modular, so that arbitrarily simple or complex interfaces can be used to
 * provide anything from debugging information through to eye candy.
 *
 * \section Copyright
 *
 * TuxOnIce is released under the GPLv2.
 *
 * Copyright (C) 1998-2001 Gabor Kuti <seasons@fornax.hu><BR>
 * Copyright (C) 1998,2001,2002 Pavel Machek <pavel@suse.cz><BR>
 * Copyright (C) 2002-2003 Florent Chabaud <fchabaud@free.fr><BR>
 * Copyright (C) 2002-2015 Nigel Cunningham (nigel at nigelcunningham com au)<BR>
 *
 * \section Credits
 *
 * Nigel would like to thank the following people for their work:
 *
 * Bernard Blackham <bernard@blackham.com.au><BR>
 * Web page & Wiki administration, some coding. A person without whom
 * TuxOnIce would not be where it is.
 *
 * Michael Frank <mhf@linuxmail.org><BR>
 * Extensive testing and help with improving stability. I was constantly
 * amazed by the quality and quantity of Michael's help.
 *
 * Pavel Machek <pavel@ucw.cz><BR>
 * Modifications, defectiveness pointing, being with Gabor at the very
 * beginning, suspend to swap space, stop all tasks. Port to 2.4.18-ac and
 * 2.5.17. Even though Pavel and I disagree on the direction suspend to
 * disk should take, I appreciate the valuable work he did in helping Gabor
 * get the concept working.
 *
 * ..and of course the myriads of TuxOnIce users who have helped diagnose
 * and fix bugs, made suggestions on how to improve the code, proofread
 * documentation, and donated time and money.
 *
 * Thanks also to corporate sponsors:
 *
 * <B>Redhat.</B>Sometime employer from May 2006 (my fault, not Redhat's!).
 *
 * <B>Cyclades.com.</B> Nigel's employers from Dec 2004 until May 2006, who
 * allowed him to work on TuxOnIce and PM related issues on company time.
 *
 * <B>LinuxFund.org.</B> Sponsored Nigel's work on TuxOnIce for four months Oct
 * 2003 to Jan 2004.
 *
 * <B>LAC Linux.</B> Donated P4 hardware that enabled development and ongoing
 * maintenance of SMP and Highmem support.
 *
 * <B>OSDL.</B> Provided access to various hardware configurations, make
 * occasional small donations to the project.
 */

#include <linux/suspend.h>
#include <linux/module.h>
#include <linux/freezer.h>
#include <generated/utsrelease.h>
#include <linux/cpu.h>
#include <linux/console.h>
#include <linux/writeback.h>
#include <linux/uaccess.h> /* for get/set_fs & KERNEL_DS on i386 */
#include <linux/bio.h>
#include <linux/kgdb.h>

#include "tuxonice.h"
#include "tuxonice_modules.h"
#include "tuxonice_sysfs.h"
#include "tuxonice_prepare_image.h"
#include "tuxonice_io.h"
#include "tuxonice_ui.h"
#include "tuxonice_power_off.h"
#include "tuxonice_storage.h"
#include "tuxonice_checksum.h"
#include "tuxonice_builtin.h"
#include "tuxonice_atomic_copy.h"
#include "tuxonice_alloc.h"
#include "tuxonice_cluster.h"

/*! Pageset metadata. */
struct pagedir pagedir2 = {2};

static mm_segment_t oldfs;
static DEFINE_MUTEX(tuxonice_in_use);
static int block_dump_save;

int toi_trace_index;

/* Binary signature if an image is present */
char tuxonice_signature[9] = "\xed\xc3\x02\xe9\x98\x56\xe5\x0c";

unsigned long boot_kernel_data_buffer;

static char *result_strings[] = {
        "Hibernation was aborted",
        "The user requested that we cancel the hibernation",
        "No storage was available",
        "Insufficient storage was available",
        "Freezing filesystems and/or tasks failed",
        "A pre-existing image was used",
        "We would free memory, but image size limit doesn't allow this",
        "Unable to free enough memory to hibernate",
        "Unable to obtain the Power Management Semaphore",
        "A device suspend/resume returned an error",
        "A system device suspend/resume returned an error",
        "The extra pages allowance is too small",
        "We were unable to successfully prepare an image",
        "TuxOnIce module initialisation failed",
        "TuxOnIce module cleanup failed",
        "I/O errors were encountered",
        "Ran out of memory",
        "An error was encountered while reading the image",
        "Platform preparation failed",
        "CPU Hotplugging failed",
        "Architecture specific preparation failed",
        "Pages needed resaving, but we were told to abort if this happens",
        "We can't hibernate at the moment (invalid resume= or filewriter "
                "target?)",
        "A hibernation preparation notifier chain member cancelled the "
                "hibernation",
        "Pre-snapshot preparation failed",
        "Pre-restore preparation failed",
        "Failed to disable usermode helpers",
        "Can't resume from alternate image",
        "Header reservation too small",
        "Device Power Management Preparation failed",
};

/**
 * toi_finish_anything - cleanup after doing anything
 * @hibernate_or_resume:        Whether finishing a cycle or attempt at
 *                                resuming.
 *
 * This is our basic clean-up routine, matching start_anything below. We
 * call cleanup routines, drop module references and restore process fs and
 * cpus allowed masks, together with the global block_dump variable's value.
 **/
void toi_finish_anything(int hibernate_or_resume)
{
        toi_running = 0;
        toi_cleanup_modules(hibernate_or_resume);
        toi_put_modules();
        if (hibernate_or_resume) {
                block_dump = block_dump_save;
                set_cpus_allowed_ptr(current, cpu_all_mask);
                toi_alloc_print_debug_stats();
                atomic_inc(&snapshot_device_available);
                unlock_system_sleep();
        }

        set_fs(oldfs);
        mutex_unlock(&tuxonice_in_use);
}

/**
 * toi_start_anything - basic initialisation for TuxOnIce
 * @toi_or_resume:        Whether starting a cycle or attempt at resuming.
 *
 * Our basic initialisation routine. Take references on modules, use the
 * kernel segment, recheck resume= if no active allocator is set, initialise
 * modules, save and reset block_dump and ensure we're running on CPU0.
 **/
int toi_start_anything(int hibernate_or_resume)
{
        mutex_lock(&tuxonice_in_use);

        oldfs = get_fs();
        set_fs(KERNEL_DS);

        toi_trace_index = 0;

        if (hibernate_or_resume) {
            lock_system_sleep();

                if (!atomic_add_unless(&snapshot_device_available, -1, 0))
                        goto snapshotdevice_unavailable;
        }

        if (hibernate_or_resume == SYSFS_HIBERNATE)
                toi_print_modules();

        if (toi_get_modules()) {
                printk(KERN_INFO "TuxOnIce: Get modules failed!\n");
                goto prehibernate_err;
        }

        if (hibernate_or_resume) {
                block_dump_save = block_dump;
                block_dump = 0;
                set_cpus_allowed_ptr(current,
                                cpumask_of(cpumask_first(cpu_online_mask)));
        }

        if (toi_initialise_modules_early(hibernate_or_resume))
                goto early_init_err;

        if (!toiActiveAllocator)
                toi_attempt_to_parse_resume_device(!hibernate_or_resume);

        if (!toi_initialise_modules_late(hibernate_or_resume)) {
            toi_running = 1; /* For the swsusp code we use :< */
            return 0;
        }

        toi_cleanup_modules(hibernate_or_resume);
early_init_err:
        if (hibernate_or_resume) {
                block_dump_save = block_dump;
                set_cpus_allowed_ptr(current, cpu_all_mask);
        }
        toi_put_modules();
prehibernate_err:
        if (hibernate_or_resume)
                atomic_inc(&snapshot_device_available);
snapshotdevice_unavailable:
        if (hibernate_or_resume)
                mutex_unlock(&pm_mutex);
        release_super_lock();
        set_fs(oldfs);
        mutex_unlock(&tuxonice_in_use);
        return -EBUSY;
}

/*
 * Nosave page tracking.
 *
 * Here rather than in prepare_image because we want to do it once only at the
 * start of a cycle.
 */

/**
 * mark_nosave_pages - set up our Nosave bitmap
 *
 * Build a bitmap of Nosave pages from the list. The bitmap allows faster
 * use when preparing the image.
 **/
static void mark_nosave_pages(void)
{
        struct nosave_region *region;

        list_for_each_entry(region, &nosave_regions, list) {
                unsigned long pfn;

                for (pfn = region->start_pfn; pfn < region->end_pfn; pfn++)
                        if (pfn_valid(pfn)) {
                                SetPageNosave(pfn_to_page(pfn));
                        }
        }
}

/**
 * allocate_bitmaps - allocate bitmaps used to record page states
 *
 * Allocate the bitmaps we use to record the various TuxOnIce related
 * page states.
 **/
static int allocate_bitmaps(void)
{
        if (toi_alloc_bitmap(&pageset1_map) ||
            toi_alloc_bitmap(&pageset1_copy_map) ||
            toi_alloc_bitmap(&pageset2_map) ||
            toi_alloc_bitmap(&io_map) ||
            toi_alloc_bitmap(&nosave_map) ||
            toi_alloc_bitmap(&free_map) ||
            toi_alloc_bitmap(&compare_map) ||
            toi_alloc_bitmap(&page_resave_map))
                return 1;

        return 0;
}

/**
 * free_bitmaps - free the bitmaps used to record page states
 *
 * Free the bitmaps allocated above. It is not an error to call
 * memory_bm_free on a bitmap that isn't currently allocated.
 **/
static void free_bitmaps(void)
{
        toi_free_bitmap(&pageset1_map);
        toi_free_bitmap(&pageset1_copy_map);
        toi_free_bitmap(&pageset2_map);
        toi_free_bitmap(&io_map);
        toi_free_bitmap(&nosave_map);
        toi_free_bitmap(&free_map);
        toi_free_bitmap(&compare_map);
        toi_free_bitmap(&page_resave_map);
}

/**
 * io_MB_per_second - return the number of MB/s read or written
 * @write:        Whether to return the speed at which we wrote.
 *
 * Calculate the number of megabytes per second that were read or written.
 **/
static int io_MB_per_second(int write)
{
        return (toi_bkd.toi_io_time[write][1]) ?
                MB((unsigned long) toi_bkd.toi_io_time[write][0]) * HZ /
                toi_bkd.toi_io_time[write][1] : 0;
}

#define SNPRINTF(a...)         do { len += scnprintf(((char *) buffer) + len, \
                count - len - 1, ## a); } while (0)

/**
 * get_debug_info - fill a buffer with debugging information
 * @buffer:        The buffer to be filled.
 * @count:        The size of the buffer, in bytes.
 *
 * Fill a (usually PAGE_SIZEd) buffer with the debugging info that we will
 * either printk or return via sysfs.
 **/
static int get_toi_debug_info(const char *buffer, int count)
{
        int len = 0, i, first_result = 1;

        SNPRINTF("TuxOnIce debugging info:\n");
        SNPRINTF("- TuxOnIce core  : " TOI_CORE_VERSION "\n");
        SNPRINTF("- Kernel Version : " UTS_RELEASE "\n");
        SNPRINTF("- Compiler vers. : %d.%d\n", __GNUC__, __GNUC_MINOR__);
        SNPRINTF("- Attempt number : %d\n", nr_hibernates);
        SNPRINTF("- Parameters     : %ld %ld %ld %d %ld %ld\n",
                        toi_result,
                        toi_bkd.toi_action,
                        toi_bkd.toi_debug_state,
                        toi_bkd.toi_default_console_level,
                        image_size_limit,
                        toi_poweroff_method);
        SNPRINTF("- Overall expected compression percentage: %d.\n",
                        100 - toi_expected_compression_ratio());
        len += toi_print_module_debug_info(((char *) buffer) + len,
                        count - len - 1);
        if (toi_bkd.toi_io_time[0][1]) {
                if ((io_MB_per_second(0) < 5) || (io_MB_per_second(1) < 5)) {
                        SNPRINTF("- I/O speed: Write %ld KB/s",
                          (KB((unsigned long) toi_bkd.toi_io_time[0][0]) * HZ /
                          toi_bkd.toi_io_time[0][1]));
                        if (toi_bkd.toi_io_time[1][1])
                                SNPRINTF(", Read %ld KB/s",
                                  (KB((unsigned long)
                                      toi_bkd.toi_io_time[1][0]) * HZ /
                                  toi_bkd.toi_io_time[1][1]));
                } else {
                        SNPRINTF("- I/O speed: Write %ld MB/s",
                         (MB((unsigned long) toi_bkd.toi_io_time[0][0]) * HZ /
                          toi_bkd.toi_io_time[0][1]));
                        if (toi_bkd.toi_io_time[1][1])
                                SNPRINTF(", Read %ld MB/s",
                                 (MB((unsigned long)
                                     toi_bkd.toi_io_time[1][0]) * HZ /
                                  toi_bkd.toi_io_time[1][1]));
                }
                SNPRINTF(".\n");
        } else
                SNPRINTF("- No I/O speed stats available.\n");
        SNPRINTF("- Extra pages    : %lu used/%lu.\n",
                        extra_pd1_pages_used, extra_pd1_pages_allowance);

        for (i = 0; i < TOI_NUM_RESULT_STATES; i++)
                if (test_result_state(i)) {
                        SNPRINTF("%s: %s.\n", first_result ?
                                        "- Result         " :
                                        "                 ",
                                        result_strings[i]);
                        first_result = 0;
                }
        if (first_result)
                SNPRINTF("- Result         : %s.\n", nr_hibernates ?
                        "Succeeded" :
                        "No hibernation attempts so far");
        return len;
}

#ifdef CONFIG_TOI_INCREMENTAL
/**
 * get_toi_page_state - fill a buffer with page state information
 * @buffer:        The buffer to be filled.
 * @count:        The size of the buffer, in bytes.
 *
 * Fill a (usually PAGE_SIZEd) buffer with the debugging info that we will
 * either printk or return via sysfs.
 **/
static int get_toi_page_state(const char *buffer, int count)
{
    int free = 0, untracked = 0, dirty = 0, ro = 0, invalid = 0, other = 0, total = 0;
    int len = 0;
    struct zone *zone;
    int allocated_bitmaps = 0;

    set_cpus_allowed_ptr(current,
            cpumask_of(cpumask_first(cpu_online_mask)));

    if (!free_map) {
        BUG_ON(toi_alloc_bitmap(&free_map));
        allocated_bitmaps = 1;
    }

    toi_generate_free_page_map();

    for_each_populated_zone(zone) {
        unsigned long loop;

        total += zone->spanned_pages;

        for (loop = 0; loop < zone->spanned_pages; loop++) {
            unsigned long pfn = zone->zone_start_pfn + loop;
            struct page *page;
            int chunk_size;

            if (!pfn_valid(pfn)) {
                continue;
            }

            chunk_size = toi_size_of_free_region(zone, pfn);
            if (chunk_size) {
                /*
                 * If the page gets allocated, it will be need
                 * saving in an image.
                 * Don't bother with explicitly removing any
                 * RO protection applied below.
                 * We'll SetPageTOI_Dirty(page) if/when it
                 * gets allocated.
                 */
                free += chunk_size;
                loop += chunk_size - 1;
                continue;
            }

            page = pfn_to_page(pfn);

            if (PageTOI_Untracked(page)) {
                untracked++;
            } else if (PageTOI_RO(page)) {
                ro++;
            } else if (PageTOI_Dirty(page)) {
                dirty++;
            } else {
                printk("Page %ld state 'other'.\n", pfn);
                other++;
            }
        }
    }

    if (allocated_bitmaps) {
        toi_free_bitmap(&free_map);
    }

    set_cpus_allowed_ptr(current, cpu_all_mask);

    SNPRINTF("TuxOnIce page breakdown:\n");
    SNPRINTF("- Free           : %d\n", free);
    SNPRINTF("- Untracked      : %d\n", untracked);
    SNPRINTF("- Read only      : %d\n", ro);
    SNPRINTF("- Dirty          : %d\n", dirty);
    SNPRINTF("- Other          : %d\n", other);
    SNPRINTF("- Invalid        : %d\n", invalid);
    SNPRINTF("- Total          : %d\n", total);
    return len;
}
#endif

/**
 * do_cleanup - cleanup after attempting to hibernate or resume
 * @get_debug_info:        Whether to allocate and return debugging info.
 *
 * Cleanup after attempting to hibernate or resume, possibly getting
 * debugging info as we do so.
 **/
static void do_cleanup(int get_debug_info, int restarting)
{
        int i = 0;
        char *buffer = NULL;

        trap_non_toi_io = 0;

        if (get_debug_info)
                toi_prepare_status(DONT_CLEAR_BAR, "Cleaning up...");

        free_checksum_pages();

        toi_cbw_restore();
        toi_free_cbw_data();

        if (get_debug_info)
                buffer = (char *) toi_get_zeroed_page(20, TOI_ATOMIC_GFP);

        if (buffer)
                i = get_toi_debug_info(buffer, PAGE_SIZE);

        toi_free_extra_pagedir_memory();

        pagedir1.size = 0;
        pagedir2.size = 0;
        set_highmem_size(pagedir1, 0);
        set_highmem_size(pagedir2, 0);

        if (boot_kernel_data_buffer) {
                if (!test_toi_state(TOI_BOOT_KERNEL))
                        toi_free_page(37, boot_kernel_data_buffer);
                boot_kernel_data_buffer = 0;
        }

        if (test_toi_state(TOI_DEVICE_HOTPLUG_LOCKED)) {
                unlock_device_hotplug();
                clear_toi_state(TOI_DEVICE_HOTPLUG_LOCKED);
        }

        clear_toi_state(TOI_BOOT_KERNEL);
        if (current->flags & PF_SUSPEND_TASK)
                thaw_processes();

        if (!restarting)
                toi_stop_other_threads();

        if (toi_keeping_image &&
            !test_result_state(TOI_ABORTED)) {
                toi_message(TOI_ANY_SECTION, TOI_LOW, 1,
                        "TuxOnIce: Not invalidating the image due "
                        "to Keep Image or Incremental Image being enabled.");
                set_result_state(TOI_KEPT_IMAGE);

                /*
                 * For an incremental image, free unused storage so
                 * swap (if any) can be used for normal system operation,
                 * if so desired.
                 */

                toiActiveAllocator->free_unused_storage();
        } else
                if (toiActiveAllocator)
                        toiActiveAllocator->remove_image();

        free_bitmaps();
        usermodehelper_enable();

        if (test_toi_state(TOI_NOTIFIERS_PREPARE)) {
                pm_notifier_call_chain(PM_POST_HIBERNATION);
                clear_toi_state(TOI_NOTIFIERS_PREPARE);
        }

        if (buffer && i) {
                /* Printk can only handle 1023 bytes, including
                 * its level mangling. */
                for (i = 0; i < 3; i++)
                        printk(KERN_ERR "%s", buffer + (1023 * i));
                toi_free_page(20, (unsigned long) buffer);
        }

        if (!restarting)
                toi_cleanup_console();

        free_attention_list();

        if (!restarting)
                toi_deactivate_storage(0);

        clear_toi_state(TOI_IGNORE_LOGLEVEL);
        clear_toi_state(TOI_TRYING_TO_RESUME);
        clear_toi_state(TOI_NOW_RESUMING);
}

/**
 * check_still_keeping_image - we kept an image; check whether to reuse it.
 *
 * We enter this routine when we have kept an image. If the user has said they
 * want to still keep it, all we need to do is powerdown. If powering down
 * means hibernating to ram and the power doesn't run out, we'll return 1.
 * If we do power off properly or the battery runs out, we'll resume via the
 * normal paths.
 *
 * If the user has said they want to remove the previously kept image, we
 * remove it, and return 0. We'll then store a new image.
 **/
static int check_still_keeping_image(void)
{
    if (toi_keeping_image) {
        if (!test_action_state(TOI_INCREMENTAL_IMAGE)) {
            printk(KERN_INFO "Image already stored: powering down "
                    "immediately.");
            do_toi_step(STEP_HIBERNATE_POWERDOWN);
            return 1;
        }
        /**
         * Incremental image - need to write new part.
         * We detect that we're writing an incremental image by looking
         * at test_result_state(TOI_KEPT_IMAGE)
         **/
        return 0;
    }

    printk(KERN_INFO "Invalidating previous image.\n");
    toiActiveAllocator->remove_image();

    return 0;
}

/**
 * toi_init - prepare to hibernate to disk
 *
 * Initialise variables & data structures, in preparation for
 * hibernating to disk.
 **/
static int toi_init(int restarting)
{
        int result, i, j;

        toi_result = 0;

        printk(KERN_INFO "Initiating a hibernation cycle.\n");

        nr_hibernates++;

        for (i = 0; i < 2; i++)
                for (j = 0; j < 2; j++)
                        toi_bkd.toi_io_time[i][j] = 0;

        if (!test_toi_state(TOI_CAN_HIBERNATE) ||
            allocate_bitmaps())
                return 1;

        mark_nosave_pages();

        if (!restarting)
                toi_prepare_console();

        result = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
        if (result) {
                set_result_state(TOI_NOTIFIERS_PREPARE_FAILED);
                return 1;
        }
        set_toi_state(TOI_NOTIFIERS_PREPARE);

        if (!restarting) {
                printk(KERN_ERR "Starting other threads.");
                toi_start_other_threads();
        }

        result = usermodehelper_disable();
        if (result) {
                printk(KERN_ERR "TuxOnIce: Failed to disable usermode "
                                "helpers\n");
                set_result_state(TOI_USERMODE_HELPERS_ERR);
                return 1;
        }

        boot_kernel_data_buffer = toi_get_zeroed_page(37, TOI_ATOMIC_GFP);
        if (!boot_kernel_data_buffer) {
                printk(KERN_ERR "TuxOnIce: Failed to allocate "
                                "boot_kernel_data_buffer.\n");
                set_result_state(TOI_OUT_OF_MEMORY);
                return 1;
        }

        toi_allocate_cbw_data();

        return 0;
}

/**
 * can_hibernate - perform basic 'Can we hibernate?' tests
 *
 * Perform basic tests that must pass if we're going to be able to hibernate:
 * Can we get the pm_mutex? Is resume= valid (we need to know where to write
 * the image header).
 **/
static int can_hibernate(void)
{
        if (!test_toi_state(TOI_CAN_HIBERNATE))
                toi_attempt_to_parse_resume_device(0);

        if (!test_toi_state(TOI_CAN_HIBERNATE)) {
                printk(KERN_INFO "TuxOnIce: Hibernation is disabled.\n"
                        "This may be because you haven't put something along "
                        "the lines of\n\nresume=swap:/dev/hda1\n\n"
                        "in lilo.conf or equivalent. (Where /dev/hda1 is your "
                        "swap partition).\n");
                set_abort_result(TOI_CANT_SUSPEND);
                return 0;
        }

        if (strlen(alt_resume_param)) {
                attempt_to_parse_alt_resume_param();

                if (!strlen(alt_resume_param)) {
                        printk(KERN_INFO "Alternate resume parameter now "
                                        "invalid. Aborting.\n");
                        set_abort_result(TOI_CANT_USE_ALT_RESUME);
                        return 0;
                }
        }

        return 1;
}

/**
 * do_post_image_write - having written an image, figure out what to do next
 *
 * After writing an image, we might load an alternate image or power down.
 * Powering down might involve hibernating to ram, in which case we also
 * need to handle reloading pageset2.
 **/
static int do_post_image_write(void)
{
        /* If switching images fails, do normal powerdown */
        if (alt_resume_param[0])
                do_toi_step(STEP_RESUME_ALT_IMAGE);

        toi_power_down();

        barrier();
        mb();
        return 0;
}

/**
 * __save_image - do the hard work of saving the image
 *
 * High level routine for getting the image saved. The key assumptions made
 * are that processes have been frozen and sufficient memory is available.
 *
 * We also exit through here at resume time, coming back from toi_hibernate
 * after the atomic restore. This is the reason for the toi_in_hibernate
 * test.
 **/
static int __save_image(void)
{
        int temp_result, did_copy = 0;

        toi_prepare_status(DONT_CLEAR_BAR, "Starting to save the image..");

        toi_message(TOI_ANY_SECTION, TOI_LOW, 1,
                " - Final values: %d and %d.",
                pagedir1.size, pagedir2.size);

        toi_cond_pause(1, "About to write pagedir2.");

        temp_result = write_pageset(&pagedir2);

        if (temp_result == -1 || test_result_state(TOI_ABORTED))
                return 1;

        toi_cond_pause(1, "About to copy pageset 1.");

        if (test_result_state(TOI_ABORTED))
                return 1;

        toi_deactivate_storage(1);

        toi_prepare_status(DONT_CLEAR_BAR, "Doing atomic copy/restore.");

        toi_in_hibernate = 1;

        if (toi_go_atomic(PMSG_FREEZE, 1))
                goto Failed;

        temp_result = toi_hibernate();

#ifdef CONFIG_KGDB
        if (test_action_state(TOI_POST_RESUME_BREAKPOINT))
                kgdb_breakpoint();
#endif

        if (!temp_result)
                did_copy = 1;

        /* We return here at resume time too! */
        toi_end_atomic(ATOMIC_ALL_STEPS, toi_in_hibernate, temp_result);

Failed:
        if (toi_activate_storage(1))
                panic("Failed to reactivate our storage.");

        /* Resume time? */
        if (!toi_in_hibernate) {
                copyback_post();
                return 0;
        }

        /* Nope. Hibernating. So, see if we can save the image... */

        if (temp_result || test_result_state(TOI_ABORTED)) {
                if (did_copy)
                        goto abort_reloading_pagedir_two;
                else
                        return 1;
        }

        toi_update_status(pagedir2.size, pagedir1.size + pagedir2.size,
                        NULL);

        if (test_result_state(TOI_ABORTED))
                goto abort_reloading_pagedir_two;

        toi_cond_pause(1, "About to write pageset1.");

        toi_message(TOI_ANY_SECTION, TOI_LOW, 1, "-- Writing pageset1");

        temp_result = write_pageset(&pagedir1);

        /* We didn't overwrite any memory, so no reread needs to be done. */
        if (test_action_state(TOI_TEST_FILTER_SPEED) ||
            test_action_state(TOI_TEST_BIO))
                return 1;

        if (temp_result == 1 || test_result_state(TOI_ABORTED))
                goto abort_reloading_pagedir_two;

        toi_cond_pause(1, "About to write header.");

        if (test_result_state(TOI_ABORTED))
                goto abort_reloading_pagedir_two;

        temp_result = write_image_header();

        if (!temp_result && !test_result_state(TOI_ABORTED))
                return 0;

abort_reloading_pagedir_two:
        temp_result = read_pageset2(1);

        /* If that failed, we're sunk. Panic! */
        if (temp_result)
                panic("Attempt to reload pagedir 2 while aborting "
                                "a hibernate failed.");

        return 1;
}

static void map_ps2_pages(int enable)
{
        unsigned long pfn = 0;

        memory_bm_position_reset(pageset2_map);
        pfn = memory_bm_next_pfn(pageset2_map, 0);

        while (pfn != BM_END_OF_MAP) {
                struct page *page = pfn_to_page(pfn);
                kernel_map_pages(page, 1, enable);
                pfn = memory_bm_next_pfn(pageset2_map, 0);
        }
}

/**
 * do_save_image - save the image and handle the result
 *
 * Save the prepared image. If we fail or we're in the path returning
 * from the atomic restore, cleanup.
 **/
static int do_save_image(void)
{
        int result;
        map_ps2_pages(0);
        result = __save_image();
        map_ps2_pages(1);
        return result;
}

/**
 * do_prepare_image - try to prepare an image
 *
 * Seek to initialise and prepare an image to be saved. On failure,
 * cleanup.
 **/
static int do_prepare_image(void)
{
        int restarting = test_result_state(TOI_EXTRA_PAGES_ALLOW_TOO_SMALL);

        if (!restarting && toi_activate_storage(0))
                return 1;

        /*
         * If kept image and still keeping image and hibernating to RAM, (non
         * incremental image case) we will return 1 after hibernating and
         * resuming (provided the power doesn't run out. In that case, we skip
         * directly to cleaning up and exiting.
         */

        if (!can_hibernate() ||
            (test_result_state(TOI_KEPT_IMAGE) &&
             check_still_keeping_image()))
                return 1;

        if (toi_init(restarting) || toi_prepare_image() ||
                        test_result_state(TOI_ABORTED))
                return 1;

        trap_non_toi_io = 1;

        return 0;
}

/**
 * do_check_can_resume - find out whether an image has been stored
 *
 * Read whether an image exists. We use the same routine as the
 * image_exists sysfs entry, and just look to see whether the
 * first character in the resulting buffer is a '1'.
 **/
int do_check_can_resume(void)
{
        int result = -1;

        if (toi_activate_storage(0))
                return -1;

        if (!test_toi_state(TOI_RESUME_DEVICE_OK))
                toi_attempt_to_parse_resume_device(1);

        if (toiActiveAllocator)
                result = toiActiveAllocator->image_exists(1);

        toi_deactivate_storage(0);
        return result;
}

/**
 * do_load_atomic_copy - load the first part of an image, if it exists
 *
 * Check whether we have an image. If one exists, do sanity checking
 * (possibly invalidating the image or even rebooting if the user
 * requests that) before loading it into memory in preparation for the
 * atomic restore.
 *
 * If and only if we have an image loaded and ready to restore, we return 1.
 **/
static int do_load_atomic_copy(void)
{
        int read_image_result = 0;

        if (sizeof(swp_entry_t) != sizeof(long)) {
                printk(KERN_WARNING "TuxOnIce: The size of swp_entry_t != size"
                        " of long. Please report this!\n");
                return 1;
        }

        if (!resume_file[0])
                printk(KERN_WARNING "TuxOnIce: "
                        "You need to use a resume= command line parameter to "
                        "tell TuxOnIce where to look for an image.\n");

        toi_activate_storage(0);

        if (!(test_toi_state(TOI_RESUME_DEVICE_OK)) &&
                !toi_attempt_to_parse_resume_device(0)) {
                /*
                 * Without a usable storage device we can do nothing -
                 * even if noresume is given
                 */

                if (!toiNumAllocators)
                        printk(KERN_ALERT "TuxOnIce: "
                          "No storage allocators have been registered.\n");
                else
                        printk(KERN_ALERT "TuxOnIce: "
                                "Missing or invalid storage location "
                                "(resume= parameter). Please correct and "
                                "rerun lilo (or equivalent) before "
                                "hibernating.\n");
                toi_deactivate_storage(0);
                return 1;
        }

        if (allocate_bitmaps())
                return 1;

        read_image_result = read_pageset1(); /* non fatal error ignored */

        if (test_toi_state(TOI_NORESUME_SPECIFIED))
                clear_toi_state(TOI_NORESUME_SPECIFIED);

        toi_deactivate_storage(0);

        if (read_image_result)
                return 1;

        return 0;
}

/**
 * prepare_restore_load_alt_image - save & restore alt image variables
 *
 * Save and restore the pageset1 maps, when loading an alternate image.
 **/
static void prepare_restore_load_alt_image(int prepare)
{
        static struct memory_bitmap *pageset1_map_save, *pageset1_copy_map_save;

        if (prepare) {
                pageset1_map_save = pageset1_map;
                pageset1_map = NULL;
                pageset1_copy_map_save = pageset1_copy_map;
                pageset1_copy_map = NULL;
                set_toi_state(TOI_LOADING_ALT_IMAGE);
                toi_reset_alt_image_pageset2_pfn();
        } else {
                toi_free_bitmap(&pageset1_map);
                pageset1_map = pageset1_map_save;
                toi_free_bitmap(&pageset1_copy_map);
                pageset1_copy_map = pageset1_copy_map_save;
                clear_toi_state(TOI_NOW_RESUMING);
                clear_toi_state(TOI_LOADING_ALT_IMAGE);
        }
}

/**
 * do_toi_step - perform a step in hibernating or resuming
 *
 * Perform a step in hibernating or resuming an image. This abstraction
 * is in preparation for implementing cluster support, and perhaps replacing
 * uswsusp too (haven't looked whether that's possible yet).
 **/
int do_toi_step(int step)
{
        switch (step) {
        case STEP_HIBERNATE_PREPARE_IMAGE:
                return do_prepare_image();
        case STEP_HIBERNATE_SAVE_IMAGE:
                return do_save_image();
        case STEP_HIBERNATE_POWERDOWN:
                return do_post_image_write();
        case STEP_RESUME_CAN_RESUME:
                return do_check_can_resume();
        case STEP_RESUME_LOAD_PS1:
                return do_load_atomic_copy();
        case STEP_RESUME_DO_RESTORE:
                /*
                 * If we succeed, this doesn't return.
                 * Instead, we return from do_save_image() in the
                 * hibernated kernel.
                 */
                return toi_atomic_restore();
        case STEP_RESUME_ALT_IMAGE:
                printk(KERN_INFO "Trying to resume alternate image.\n");
                toi_in_hibernate = 0;
                save_restore_alt_param(SAVE, NOQUIET);
                prepare_restore_load_alt_image(1);
                if (!do_check_can_resume()) {
                        printk(KERN_INFO "Nothing to resume from.\n");
                        goto out;
                }
                if (!do_load_atomic_copy())
                        toi_atomic_restore();

                printk(KERN_INFO "Failed to load image.\n");
out:
                prepare_restore_load_alt_image(0);
                save_restore_alt_param(RESTORE, NOQUIET);
                break;
        case STEP_CLEANUP:
                do_cleanup(1, 0);
                break;
        case STEP_QUIET_CLEANUP:
                do_cleanup(0, 0);
                break;
        }

        return 0;
}

/* -- Functions for kickstarting a hibernate or resume --- */

/**
 * toi_try_resume - try to do the steps in resuming
 *
 * Check if we have an image and if so try to resume. Clear the status
 * flags too.
 **/
void toi_try_resume(void)
{
        set_toi_state(TOI_TRYING_TO_RESUME);
        resume_attempted = 1;

        current->flags |= PF_MEMALLOC;
        toi_start_other_threads();

        if (do_toi_step(STEP_RESUME_CAN_RESUME) &&
                        !do_toi_step(STEP_RESUME_LOAD_PS1))
                do_toi_step(STEP_RESUME_DO_RESTORE);

        toi_stop_other_threads();
        do_cleanup(0, 0);

        current->flags &= ~PF_MEMALLOC;

        clear_toi_state(TOI_IGNORE_LOGLEVEL);
        clear_toi_state(TOI_TRYING_TO_RESUME);
        clear_toi_state(TOI_NOW_RESUMING);
}

/**
 * toi_sys_power_disk_try_resume - wrapper calling toi_try_resume
 *
 * Wrapper for when __toi_try_resume is called from swsusp resume path,
 * rather than from echo > /sys/power/tuxonice/do_resume.
 **/
static void toi_sys_power_disk_try_resume(void)
{
        resume_attempted = 1;

        /*
         * There's a comment in kernel/power/disk.c that indicates
         * we should be able to use mutex_lock_nested below. That
         * doesn't seem to cut it, though, so let's just turn lockdep
         * off for now.
         */
        lockdep_off();

        if (toi_start_anything(SYSFS_RESUMING))
                goto out;

        toi_try_resume();

        /*
         * For initramfs, we have to clear the boot time
         * flag after trying to resume
         */
        clear_toi_state(TOI_BOOT_TIME);

        toi_finish_anything(SYSFS_RESUMING);
out:
        lockdep_on();
}

/**
 * toi_try_hibernate - try to start a hibernation cycle
 *
 * Start a hibernation cycle, coming in from either
 * echo > /sys/power/tuxonice/do_suspend
 *
 * or
 *
 * echo disk > /sys/power/state
 *
 * In the later case, we come in without pm_sem taken; in the
 * former, it has been taken.
 **/
int toi_try_hibernate(void)
{
        int result = 0, sys_power_disk = 0, retries = 0;

        if (!mutex_is_locked(&tuxonice_in_use)) {
                /* Came in via /sys/power/disk */
                if (toi_start_anything(SYSFS_HIBERNATING))
                        return -EBUSY;
                sys_power_disk = 1;
        }

        current->flags |= PF_MEMALLOC;

        if (test_toi_state(TOI_CLUSTER_MODE)) {
                toi_initiate_cluster_hibernate();
                goto out;
        }

prepare:
        result = do_toi_step(STEP_HIBERNATE_PREPARE_IMAGE);

        if (result)
                goto out;

        if (test_action_state(TOI_FREEZER_TEST))
                goto out_restore_gfp_mask;

        result = do_toi_step(STEP_HIBERNATE_SAVE_IMAGE);

        if (test_result_state(TOI_EXTRA_PAGES_ALLOW_TOO_SMALL)) {
                if (retries < 2) {
                        do_cleanup(0, 1);
                        retries++;
                        clear_result_state(TOI_ABORTED);
                        extra_pd1_pages_allowance = extra_pd1_pages_used + 500;
                        printk(KERN_INFO "Automatically adjusting the extra"
                                " pages allowance to %ld and restarting.\n",
                                extra_pd1_pages_allowance);
                        pm_restore_gfp_mask();
                        goto prepare;
                }

                printk(KERN_INFO "Adjusted extra pages allowance twice and "
                        "still couldn't hibernate successfully. Giving up.");
        }

        /* This code runs at resume time too! */
        if (!result && toi_in_hibernate)
                result = do_toi_step(STEP_HIBERNATE_POWERDOWN);

out_restore_gfp_mask:
        pm_restore_gfp_mask();
out:
        do_cleanup(1, 0);
        current->flags &= ~PF_MEMALLOC;

        if (sys_power_disk)
                toi_finish_anything(SYSFS_HIBERNATING);

        return result;
}

/*
 * channel_no: If !0, -c <channel_no> is added to args (userui).
 */
int toi_launch_userspace_program(char *command, int channel_no,
                int wait, int debug)
{
        int retval;
        static char *envp[] = {
                        "HOME=/",
                        "TERM=linux",
                        "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
                        NULL };
        static char *argv[] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
                };
        char *channel = NULL;
        int arg = 0, size;
        char test_read[255];
        char *orig_posn = command;

        if (!strlen(orig_posn))
                return 1;

        if (channel_no) {
                channel = toi_kzalloc(4, 6, GFP_KERNEL);
                if (!channel) {
                        printk(KERN_INFO "Failed to allocate memory in "
                                "preparing to launch userspace program.\n");
                        return 1;
                }
        }

        /* Up to 6 args supported */
        while (arg < 6) {
                sscanf(orig_posn, "%s", test_read);
                size = strlen(test_read);
                if (!(size))
                        break;
                argv[arg] = toi_kzalloc(5, size + 1, TOI_ATOMIC_GFP);
                strcpy(argv[arg], test_read);
                orig_posn += size + 1;
                *test_read = 0;
                arg++;
        }

        if (channel_no) {
                sprintf(channel, "-c%d", channel_no);
                argv[arg] = channel;
        } else
                arg--;

        if (debug) {
                argv[++arg] = toi_kzalloc(5, 8, TOI_ATOMIC_GFP);
                strcpy(argv[arg], "--debug");
        }

        retval = call_usermodehelper(argv[0], argv, envp, wait);

        /*
         * If the program reports an error, retval = 256. Don't complain
         * about that here.
         */
        if (retval && retval != 256)
                printk(KERN_ERR "Failed to launch userspace program '%s': "
                                "Error %d\n", command, retval);

        {
                int i;
                for (i = 0; i < arg; i++)
                        if (argv[i] && argv[i] != channel)
                                toi_kfree(5, argv[i], sizeof(*argv[i]));
        }

        toi_kfree(4, channel, sizeof(*channel));

        return retval;
}

/*
 * This array contains entries that are automatically registered at
 * boot. Modules and the console code register their own entries separately.
 */
static struct toi_sysfs_data sysfs_params[] = {
        SYSFS_LONG("extra_pages_allowance", SYSFS_RW,
                        &extra_pd1_pages_allowance, 0, LONG_MAX, 0),
        SYSFS_CUSTOM("image_exists", SYSFS_RW, image_exists_read,
                        image_exists_write, SYSFS_NEEDS_SM_FOR_BOTH, NULL),
        SYSFS_STRING("resume", SYSFS_RW, resume_file, 255,
                        SYSFS_NEEDS_SM_FOR_WRITE,
                        attempt_to_parse_resume_device2),
        SYSFS_STRING("alt_resume_param", SYSFS_RW, alt_resume_param, 255,
                        SYSFS_NEEDS_SM_FOR_WRITE,
                        attempt_to_parse_alt_resume_param),
        SYSFS_CUSTOM("debug_info", SYSFS_READONLY, get_toi_debug_info, NULL, 0,
                        NULL),
        SYSFS_BIT("ignore_rootfs", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_IGNORE_ROOTFS, 0),
        SYSFS_LONG("image_size_limit", SYSFS_RW, &image_size_limit, -2,
                        INT_MAX, 0),
        SYSFS_UL("last_result", SYSFS_RW, &toi_result, 0, 0, 0),
        SYSFS_BIT("no_multithreaded_io", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_NO_MULTITHREADED_IO, 0),
        SYSFS_BIT("no_flusher_thread", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_NO_FLUSHER_THREAD, 0),
        SYSFS_BIT("full_pageset2", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_PAGESET2_FULL, 0),
        SYSFS_BIT("reboot", SYSFS_RW, &toi_bkd.toi_action, TOI_REBOOT, 0),
        SYSFS_BIT("replace_swsusp", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_REPLACE_SWSUSP, 0),
        SYSFS_STRING("resume_commandline", SYSFS_RW,
                        toi_bkd.toi_nosave_commandline, COMMAND_LINE_SIZE, 0,
                        NULL),
        SYSFS_STRING("version", SYSFS_READONLY, TOI_CORE_VERSION, 0, 0, NULL),
        SYSFS_BIT("freezer_test", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_FREEZER_TEST, 0),
        SYSFS_BIT("test_bio", SYSFS_RW, &toi_bkd.toi_action, TOI_TEST_BIO, 0),
        SYSFS_BIT("test_filter_speed", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_TEST_FILTER_SPEED, 0),
        SYSFS_BIT("no_pageset2", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_NO_PAGESET2, 0),
        SYSFS_BIT("no_pageset2_if_unneeded", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_NO_PS2_IF_UNNEEDED, 0),
        SYSFS_STRING("binary_signature", SYSFS_READONLY,
                        tuxonice_signature, 9, 0, NULL),
        SYSFS_INT("max_workers", SYSFS_RW, &toi_max_workers, 0, NR_CPUS, 0,
                        NULL),
#ifdef CONFIG_KGDB
        SYSFS_BIT("post_resume_breakpoint", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_POST_RESUME_BREAKPOINT, 0),
#endif
        SYSFS_BIT("no_readahead", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_NO_READAHEAD, 0),
        SYSFS_BIT("trace_debug_on", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_TRACE_DEBUG_ON, 0),
#ifdef CONFIG_TOI_KEEP_IMAGE
        SYSFS_BIT("keep_image", SYSFS_RW , &toi_bkd.toi_action, TOI_KEEP_IMAGE,
                        0),
#endif
#ifdef CONFIG_TOI_INCREMENTAL
        SYSFS_CUSTOM("pagestate", SYSFS_READONLY, get_toi_page_state, NULL, 0,
                        NULL),
        SYSFS_BIT("incremental", SYSFS_RW, &toi_bkd.toi_action,
                        TOI_INCREMENTAL_IMAGE, 1),
#endif
};

static struct toi_core_fns my_fns = {
        .get_nonconflicting_page = __toi_get_nonconflicting_page,
        .post_context_save = __toi_post_context_save,
        .try_hibernate = toi_try_hibernate,
        .try_resume = toi_sys_power_disk_try_resume,
};

/**
 * core_load - initialisation of TuxOnIce core
 *
 * Initialise the core, beginning with sysfs. Checksum and so on are part of
 * the core, but have their own initialisation routines because they either
 * aren't compiled in all the time or have their own subdirectories.
 **/
static __init int core_load(void)
{
        int i,
            numfiles = sizeof(sysfs_params) / sizeof(struct toi_sysfs_data);

        printk(KERN_INFO "TuxOnIce " TOI_CORE_VERSION
                        " (http://tuxonice.net)\n");

        if (!hibernation_available()) {
          printk(KERN_INFO "TuxOnIce disabled due to request for hibernation"
              " to be disabled in this kernel.\n");
          return 1;
        }

        if (toi_sysfs_init())
                return 1;

        for (i = 0; i < numfiles; i++)
                toi_register_sysfs_file(tuxonice_kobj, &sysfs_params[i]);

        toi_core_fns = &my_fns;

        if (toi_alloc_init())
                return 1;
        if (toi_checksum_init())
                return 1;
        if (toi_usm_init())
                return 1;
        if (toi_ui_init())
                return 1;
        if (toi_poweroff_init())
                return 1;
        if (toi_cluster_init())
                return 1;
        if (toi_cbw_init())
                return 1;

        return 0;
}

late_initcall(core_load);