// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/kernel/power/user.c
 *
 * This file provides the user space interface for software suspend/resume.
 *
 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
 */

#include <linux/suspend.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 <linux/uaccess.h>

#include "power.h"

static bool need_wait;

static struct snapshot_data {
        struct snapshot_handle handle;
        int swap;
        int mode;
        bool frozen;
        bool ready;
        bool platform_support;
        bool free_bitmaps;
        dev_t dev;
} snapshot_state;

int is_hibernate_resume_dev(dev_t dev)
{
        return hibernation_available() && snapshot_state.dev == dev;
}

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

        if (!hibernation_available())
                return -EPERM;

        sleep_flags = lock_system_sleep();

        if (!hibernate_acquire()) {
                error = -EBUSY;
                goto Unlock;
        }

        if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
                hibernate_release();
                error = -ENOSYS;
                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 = swap_type_of(swsusp_resume_device, 0);
                data->mode = O_RDONLY;
                data->free_bitmaps = false;
                error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
        } else {
                /*
                 * Resuming.  We may need to wait for the image device to
                 * appear.
                 */
                need_wait = true;

                data->swap = -1;
                data->mode = O_WRONLY;
                error = pm_notifier_call_chain_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE);
                if (!error) {
                        error = create_basic_memory_bitmaps();
                        data->free_bitmaps = !error;
                }
        }
        if (error)
                hibernate_release();

        data->frozen = false;
        data->ready = false;
        data->platform_support = false;
        data->dev = 0;

 Unlock:
        unlock_system_sleep(sleep_flags);

        return error;
}

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

        sleep_flags = lock_system_sleep();

        swsusp_free();
        data = filp->private_data;
        data->dev = 0;
        free_all_swap_pages(data->swap);
        if (data->frozen) {
                pm_restore_gfp_mask();
                free_basic_memory_bitmaps();
                thaw_processes();
        } else if (data->free_bitmaps) {
                free_basic_memory_bitmaps();
        }
        pm_notifier_call_chain(data->mode == O_RDONLY ?
                        PM_POST_HIBERNATION : PM_POST_RESTORE);
        hibernate_release();

        unlock_system_sleep(sleep_flags);

        return 0;
}

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

        sleep_flags = 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(sleep_flags);

        return res;
}

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

        if (need_wait) {
                wait_for_device_probe();
                need_wait = false;
        }

        sleep_flags = 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;
        }

        if (!data_of(data->handle)) {
                res = -EINVAL;
                goto unlock;
        }

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

        return res;
}

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

static int snapshot_set_swap_area(struct snapshot_data *data,
                void __user *argp)
{
        sector_t offset;
        dev_t swdev;

        if (swsusp_swap_in_use())
                return -EPERM;

        if (in_compat_syscall()) {
                struct compat_resume_swap_area swap_area;

                if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
                        return -EFAULT;
                swdev = new_decode_dev(swap_area.dev);
                offset = swap_area.offset;
        } else {
                struct resume_swap_area swap_area;

                if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
                        return -EFAULT;
                swdev = new_decode_dev(swap_area.dev);
                offset = swap_area.offset;
        }

        /*
         * User space encodes device types as two-byte values,
         * so we need to recode them
         */
        data->swap = swap_type_of(swdev, offset);
        if (data->swap < 0)
                return swdev ? -ENODEV : -EINVAL;
        data->dev = swdev;
        return 0;
}

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 (need_wait) {
                wait_for_device_probe();
                need_wait = false;
        }

        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(&system_transition_mutex))
                return -EBUSY;

        lock_device_hotplug();
        data = filp->private_data;

        switch (cmd) {

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

                error = pm_sleep_fs_sync();
                if (error)
                        break;

                error = freeze_processes();
                if (error)
                        break;

                error = create_basic_memory_bitmaps();
                if (error)
                        thaw_processes();
                else
                        data->frozen = true;

                break;

        case SNAPSHOT_UNFREEZE:
                if (!data->frozen || data->ready)
                        break;
                pm_restore_gfp_mask();
                free_basic_memory_bitmaps();
                data->free_bitmaps = false;
                thaw_processes();
                data->frozen = false;
                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:
                error = snapshot_write_finalize(&data->handle);
                if (error)
                        break;
                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 = false;
                /*
                 * 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 = false;
                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:
                error = snapshot_set_swap_area(data, (void __user *)arg);
                break;

        default:
                error = -ENOTTY;

        }

        unlock_device_hotplug();
        mutex_unlock(&system_transition_mutex);

        return error;
}

#ifdef CONFIG_COMPAT
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:
        case SNAPSHOT_CREATE_IMAGE:
        case SNAPSHOT_SET_SWAP_AREA:
                return snapshot_ioctl(file, cmd,
                                      (unsigned long) compat_ptr(arg));
        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,
        .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);