user.c

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/*
 * linux/kernel/power/user.c
 *
 * This file provides the user space interface for software suspend/resume.
 *
 * Copyright (C) 2006 Rafael J. Wysocki <[email protected]>
 *
 * This file is released under the GPLv2.
 *
 */

#include <linux/suspend.h>
#include <linux/syscalls.h>
#include <linux/reboot.h>
#include <linux/string.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/pm.h>
#include <linux/fs.h>
#include <linux/compat.h>
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/freezer.h>

#include <asm/uaccess.h>

#include "power.h"


#define SNAPSHOT_MINOR  231

static struct snapshot_data {
    struct snapshot_handle handle;
    int swap;
    int mode;
    char frozen;
    char ready;
    char platform_support;
} snapshot_state;

atomic_t snapshot_device_available = ATOMIC_INIT(1);

static int snapshot_open(struct inode *inode, struct file *filp)
{
    struct snapshot_data *data;
    int error;

    lock_system_sleep();

    if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
        error = -EBUSY;
        goto Unlock;
    }

    if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
        atomic_inc(&snapshot_device_available);
        error = -ENOSYS;
        goto Unlock;
    }
    if(create_basic_memory_bitmaps()) {
        atomic_inc(&snapshot_device_available);
        error = -ENOMEM;
        goto Unlock;
    }
    nonseekable_open(inode, filp);
    data = &snapshot_state;
    filp->private_data = data;
    memset(&data->handle, 0, sizeof(struct snapshot_handle));
    if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
        /* Hibernating.  The image device should be accessible. */
        data->swap = swsusp_resume_device ?
            swap_type_of(swsusp_resume_device, 0, NULL) : -1;
        data->mode = O_RDONLY;
        error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
        if (error)
            pm_notifier_call_chain(PM_POST_HIBERNATION);
    } else {
        /*
         * Resuming.  We may need to wait for the image device to
         * appear.
         */
        wait_for_device_probe();

        data->swap = -1;
        data->mode = O_WRONLY;
        error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
        if (error)
            pm_notifier_call_chain(PM_POST_RESTORE);
    }
    if (error) {
        free_basic_memory_bitmaps();
        atomic_inc(&snapshot_device_available);
    }
    data->frozen = 0;
    data->ready = 0;
    data->platform_support = 0;

 Unlock:
    unlock_system_sleep();

    return error;
}

static int snapshot_release(struct inode *inode, struct file *filp)
{
    struct snapshot_data *data;

    lock_system_sleep();

    swsusp_free();
    free_basic_memory_bitmaps();
    data = filp->private_data;
    free_all_swap_pages(data->swap);
    if (data->frozen) {
        pm_restore_gfp_mask();
        thaw_processes();
    }
    pm_notifier_call_chain(data->mode == O_RDONLY ?
            PM_POST_HIBERNATION : PM_POST_RESTORE);
    atomic_inc(&snapshot_device_available);

    unlock_system_sleep();

    return 0;
}

static ssize_t snapshot_read(struct file *filp, char __user *buf,
                             size_t count, loff_t *offp)
{
    struct snapshot_data *data;
    ssize_t res;
    loff_t pg_offp = *offp & ~PAGE_MASK;

    lock_system_sleep();

    data = filp->private_data;
    if (!data->ready) {
        res = -ENODATA;
        goto Unlock;
    }
    if (!pg_offp) { /* on page boundary? */
        res = snapshot_read_next(&data->handle);
        if (res <= 0)
            goto Unlock;
    } else {
        res = PAGE_SIZE - pg_offp;
    }

    res = simple_read_from_buffer(buf, count, &pg_offp,
            data_of(data->handle), res);
    if (res > 0)
        *offp += res;

 Unlock:
    unlock_system_sleep();

    return res;
}

static ssize_t snapshot_write(struct file *filp, const char __user *buf,
                              size_t count, loff_t *offp)
{
    struct snapshot_data *data;
    ssize_t res;
    loff_t pg_offp = *offp & ~PAGE_MASK;

    lock_system_sleep();

    data = filp->private_data;

    if (!pg_offp) {
        res = snapshot_write_next(&data->handle);
        if (res <= 0)
            goto unlock;
    } else {
        res = PAGE_SIZE - pg_offp;
    }

    res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
            buf, count);
    if (res > 0)
        *offp += res;
unlock:
    unlock_system_sleep();

    return res;
}

static long snapshot_ioctl(struct file *filp, unsigned int cmd,
                            unsigned long arg)
{
    int error = 0;
    struct snapshot_data *data;
    loff_t size;
    sector_t offset;

    if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
        return -ENOTTY;
    if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
        return -ENOTTY;
    if (!capable(CAP_SYS_ADMIN))
        return -EPERM;

    if (!mutex_trylock(&pm_mutex))
        return -EBUSY;

    data = filp->private_data;

    switch (cmd) {

    case SNAPSHOT_FREEZE:
        if (data->frozen)
            break;

        printk("Syncing filesystems ... ");
        sys_sync();
        printk("done.\n");

        error = freeze_processes();
        if (!error)
            data->frozen = 1;
        break;

    case SNAPSHOT_UNFREEZE:
        if (!data->frozen || data->ready)
            break;
        pm_restore_gfp_mask();
        thaw_processes();
        data->frozen = 0;
        break;

    case SNAPSHOT_CREATE_IMAGE:
        if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
            error = -EPERM;
            break;
        }
        pm_restore_gfp_mask();
        error = hibernation_snapshot(data->platform_support);
        if (!error) {
            error = put_user(in_suspend, (int __user *)arg);
            data->ready = !freezer_test_done && !error;
            freezer_test_done = false;
        }
        break;

    case SNAPSHOT_ATOMIC_RESTORE:
        snapshot_write_finalize(&data->handle);
        if (data->mode != O_WRONLY || !data->frozen ||
            !snapshot_image_loaded(&data->handle)) {
            error = -EPERM;
            break;
        }
        error = hibernation_restore(data->platform_support);
        break;

    case SNAPSHOT_FREE:
        swsusp_free();
        memset(&data->handle, 0, sizeof(struct snapshot_handle));
        data->ready = 0;
        /*
         * It is necessary to thaw kernel threads here, because
         * SNAPSHOT_CREATE_IMAGE may be invoked directly after
         * SNAPSHOT_FREE.  In that case, if kernel threads were not
         * thawed, the preallocation of memory carried out by
         * hibernation_snapshot() might run into problems (i.e. it
         * might fail or even deadlock).
         */
        thaw_kernel_threads();
        break;

    case SNAPSHOT_PREF_IMAGE_SIZE:
        image_size = arg;
        break;

    case SNAPSHOT_GET_IMAGE_SIZE:
        if (!data->ready) {
            error = -ENODATA;
            break;
        }
        size = snapshot_get_image_size();
        size <<= PAGE_SHIFT;
        error = put_user(size, (loff_t __user *)arg);
        break;

    case SNAPSHOT_AVAIL_SWAP_SIZE:
        size = count_swap_pages(data->swap, 1);
        size <<= PAGE_SHIFT;
        error = put_user(size, (loff_t __user *)arg);
        break;

    case SNAPSHOT_ALLOC_SWAP_PAGE:
        if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
            error = -ENODEV;
            break;
        }
        offset = alloc_swapdev_block(data->swap);
        if (offset) {
            offset <<= PAGE_SHIFT;
            error = put_user(offset, (loff_t __user *)arg);
        } else {
            error = -ENOSPC;
        }
        break;

    case SNAPSHOT_FREE_SWAP_PAGES:
        if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
            error = -ENODEV;
            break;
        }
        free_all_swap_pages(data->swap);
        break;

    case SNAPSHOT_S2RAM:
        if (!data->frozen) {
            error = -EPERM;
            break;
        }
        /*
         * Tasks are frozen and the notifiers have been called with
         * PM_HIBERNATION_PREPARE
         */
        error = suspend_devices_and_enter(PM_SUSPEND_MEM);
        data->ready = 0;
        break;

    case SNAPSHOT_PLATFORM_SUPPORT:
        data->platform_support = !!arg;
        break;

    case SNAPSHOT_POWER_OFF:
        if (data->platform_support)
            error = hibernation_platform_enter();
        break;

    case SNAPSHOT_SET_SWAP_AREA:
        if (swsusp_swap_in_use()) {
            error = -EPERM;
        } else {
            struct resume_swap_area swap_area;
            dev_t swdev;

            error = copy_from_user(&swap_area, (void __user *)arg,
                    sizeof(struct resume_swap_area));
            if (error) {
                error = -EFAULT;
                break;
            }

            /*
             * User space encodes device types as two-byte values,
             * so we need to recode them
             */
            swdev = new_decode_dev(swap_area.dev);
            if (swdev) {
                offset = swap_area.offset;
                data->swap = swap_type_of(swdev, offset, NULL);
                if (data->swap < 0)
                    error = -ENODEV;
            } else {
                data->swap = -1;
                error = -EINVAL;
            }
        }
        break;

    default:
        error = -ENOTTY;

    }

    mutex_unlock(&pm_mutex);

    return error;
}

#ifdef CONFIG_COMPAT

struct compat_resume_swap_area {
    compat_loff_t offset;
    u32 dev;
} __packed;

static long
snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));

    switch (cmd) {
    case SNAPSHOT_GET_IMAGE_SIZE:
    case SNAPSHOT_AVAIL_SWAP_SIZE:
    case SNAPSHOT_ALLOC_SWAP_PAGE: {
        compat_loff_t __user *uoffset = compat_ptr(arg);
        loff_t offset;
        mm_segment_t old_fs;
        int err;

        old_fs = get_fs();
        set_fs(KERNEL_DS);
        err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
        set_fs(old_fs);
        if (!err && put_user(offset, uoffset))
            err = -EFAULT;
        return err;
    }

    case SNAPSHOT_CREATE_IMAGE:
        return snapshot_ioctl(file, cmd,
                      (unsigned long) compat_ptr(arg));

    case SNAPSHOT_SET_SWAP_AREA: {
        struct compat_resume_swap_area __user *u_swap_area =
            compat_ptr(arg);
        struct resume_swap_area swap_area;
        mm_segment_t old_fs;
        int err;

        err = get_user(swap_area.offset, &u_swap_area->offset);
        err |= get_user(swap_area.dev, &u_swap_area->dev);
        if (err)
            return -EFAULT;
        old_fs = get_fs();
        set_fs(KERNEL_DS);
        err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
                     (unsigned long) &swap_area);
        set_fs(old_fs);
        return err;
    }

    default:
        return snapshot_ioctl(file, cmd, arg);
    }
}

#endif /* CONFIG_COMPAT */

static const struct file_operations snapshot_fops = {
    .open = snapshot_open,
    .release = snapshot_release,
    .read = snapshot_read,
    .write = snapshot_write,
    .llseek = no_llseek,
    .unlocked_ioctl = snapshot_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl = snapshot_compat_ioctl,
#endif
};

static struct miscdevice snapshot_device = {
    .minor = SNAPSHOT_MINOR,
    .name = "snapshot",
    .fops = &snapshot_fops,
};

static int __init snapshot_device_init(void)
{
    return misc_register(&snapshot_device);
};

device_initcall(snapshot_device_init);