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   1 /*
   2  * linux/kernel/power/user.c
   3  *
   4  * This file provides the user space interface for software suspend/resume.
   5  *
   6  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
   7  *
   8  * This file is released under the GPLv2.
   9  *
  10  */
  11
  12 #include <linux/suspend.h>
  13 #include <linux/syscalls.h>
  14 #include <linux/string.h>
  15 #include <linux/device.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/mm.h>
  18 #include <linux/swap.h>
  19 #include <linux/swapops.h>
  20 #include <linux/pm.h>
  21 #include <linux/fs.h>
  22
  23 #include <asm/uaccess.h>
  24
  25 #include "power.h"
  26
  27 #define SNAPSHOT_MINOR  231
  28
  29 static struct snapshot_data {
  30         struct snapshot_handle handle;
  31         int swap;
  32         struct bitmap_page *bitmap;
  33         int mode;
  34         char frozen;
  35         char ready;
  36 } snapshot_state;
  37
  38 static atomic_t device_available = ATOMIC_INIT(1);
  39
  40 static int snapshot_open(struct inode *inode, struct file *filp)
  41 {
  42         struct snapshot_data *data;
  43
  44         if (!atomic_add_unless(&device_available, -1, 0))
  45                 return -EBUSY;
  46
  47         if ((filp->f_flags & O_ACCMODE) == O_RDWR)
  48                 return -ENOSYS;
  49
  50         nonseekable_open(inode, filp);
  51         data = &snapshot_state;
  52         filp->private_data = data;
  53         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  54         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  55                 data->swap = swsusp_resume_device ? swap_type_of(swsusp_resume_device) : -1;
  56                 data->mode = O_RDONLY;
  57         } else {
  58                 data->swap = -1;
  59                 data->mode = O_WRONLY;
  60         }
  61         data->bitmap = NULL;
  62         data->frozen = 0;
  63         data->ready = 0;
  64
  65         return 0;
  66 }
  67
  68 static int snapshot_release(struct inode *inode, struct file *filp)
  69 {
  70         struct snapshot_data *data;
  71
  72         swsusp_free();
  73         data = filp->private_data;
  74         free_all_swap_pages(data->swap, data->bitmap);
  75         free_bitmap(data->bitmap);
  76         if (data->frozen) {
  77                 down(&pm_sem);
  78                 thaw_processes();
  79                 enable_nonboot_cpus();
  80                 up(&pm_sem);
  81         }
  82         atomic_inc(&device_available);
  83         return 0;
  84 }
  85
  86 static ssize_t snapshot_read(struct file *filp, char __user *buf,
  87                              size_t count, loff_t *offp)
  88 {
  89         struct snapshot_data *data;
  90         ssize_t res;
  91
  92         data = filp->private_data;
  93         res = snapshot_read_next(&data->handle, count);
  94         if (res > 0) {
  95                 if (copy_to_user(buf, data_of(data->handle), res))
  96                         res = -EFAULT;
  97                 else
  98                         *offp = data->handle.offset;
  99         }
 100         return res;
 101 }
 102
 103 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 104                               size_t count, loff_t *offp)
 105 {
 106         struct snapshot_data *data;
 107         ssize_t res;
 108
 109         data = filp->private_data;
 110         res = snapshot_write_next(&data->handle, count);
 111         if (res > 0) {
 112                 if (copy_from_user(data_of(data->handle), buf, res))
 113                         res = -EFAULT;
 114                 else
 115                         *offp = data->handle.offset;
 116         }
 117         return res;
 118 }
 119
 120 static int snapshot_ioctl(struct inode *inode, struct file *filp,
 121                           unsigned int cmd, unsigned long arg)
 122 {
 123         int error = 0;
 124         struct snapshot_data *data;
 125         loff_t offset, avail;
 126
 127         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 128                 return -ENOTTY;
 129         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 130                 return -ENOTTY;
 131         if (!capable(CAP_SYS_ADMIN))
 132                 return -EPERM;
 133
 134         data = filp->private_data;
 135
 136         switch (cmd) {
 137
 138         case SNAPSHOT_FREEZE:
 139                 if (data->frozen)
 140                         break;
 141                 down(&pm_sem);
 142                 pm_prepare_console();
 143                 disable_nonboot_cpus();
 144                 if (freeze_processes()) {
 145                         thaw_processes();
 146                         enable_nonboot_cpus();
 147                         pm_restore_console();
 148                         error = -EBUSY;
 149                 }
 150                 up(&pm_sem);
 151                 if (!error)
 152                         data->frozen = 1;
 153                 break;
 154
 155         case SNAPSHOT_UNFREEZE:
 156                 if (!data->frozen)
 157                         break;
 158                 down(&pm_sem);
 159                 thaw_processes();
 160                 enable_nonboot_cpus();
 161                 pm_restore_console();
 162                 up(&pm_sem);
 163                 data->frozen = 0;
 164                 break;
 165
 166         case SNAPSHOT_ATOMIC_SNAPSHOT:
 167                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 168                         error = -EPERM;
 169                         break;
 170                 }
 171                 down(&pm_sem);
 172                 /* Free memory before shutting down devices. */
 173                 error = swsusp_shrink_memory();
 174                 if (!error) {
 175                         error = device_suspend(PMSG_FREEZE);
 176                         if (!error) {
 177                                 in_suspend = 1;
 178                                 error = swsusp_suspend();
 179                                 device_resume();
 180                         }
 181                 }
 182                 up(&pm_sem);
 183                 if (!error)
 184                         error = put_user(in_suspend, (unsigned int __user *)arg);
 185                 if (!error)
 186                         data->ready = 1;
 187                 break;
 188
 189         case SNAPSHOT_ATOMIC_RESTORE:
 190                 if (data->mode != O_WRONLY || !data->frozen ||
 191                     !snapshot_image_loaded(&data->handle)) {
 192                         error = -EPERM;
 193                         break;
 194                 }
 195                 down(&pm_sem);
 196                 pm_prepare_console();
 197                 error = device_suspend(PMSG_FREEZE);
 198                 if (!error) {
 199                         error = swsusp_resume();
 200                         device_resume();
 201                 }
 202                 pm_restore_console();
 203                 up(&pm_sem);
 204                 break;
 205
 206         case SNAPSHOT_FREE:
 207                 swsusp_free();
 208                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 209                 data->ready = 0;
 210                 break;
 211
 212         case SNAPSHOT_SET_IMAGE_SIZE:
 213                 image_size = arg;
 214                 break;
 215
 216         case SNAPSHOT_AVAIL_SWAP:
 217                 avail = count_swap_pages(data->swap, 1);
 218                 avail <<= PAGE_SHIFT;
 219                 error = put_user(avail, (loff_t __user *)arg);
 220                 break;
 221
 222         case SNAPSHOT_GET_SWAP_PAGE:
 223                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 224                         error = -ENODEV;
 225                         break;
 226                 }
 227                 if (!data->bitmap) {
 228                         data->bitmap = alloc_bitmap(count_swap_pages(data->swap, 0));
 229                         if (!data->bitmap) {
 230                                 error = -ENOMEM;
 231                                 break;
 232                         }
 233                 }
 234                 offset = alloc_swap_page(data->swap, data->bitmap);
 235                 if (offset) {
 236                         offset <<= PAGE_SHIFT;
 237                         error = put_user(offset, (loff_t __user *)arg);
 238                 } else {
 239                         error = -ENOSPC;
 240                 }
 241                 break;
 242
 243         case SNAPSHOT_FREE_SWAP_PAGES:
 244                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 245                         error = -ENODEV;
 246                         break;
 247                 }
 248                 free_all_swap_pages(data->swap, data->bitmap);
 249                 free_bitmap(data->bitmap);
 250                 data->bitmap = NULL;
 251                 break;
 252
 253         case SNAPSHOT_SET_SWAP_FILE:
 254                 if (!data->bitmap) {
 255                         /*
 256                          * User space encodes device types as two-byte values,
 257                          * so we need to recode them
 258                          */
 259                         if (old_decode_dev(arg)) {
 260                                 data->swap = swap_type_of(old_decode_dev(arg));
 261                                 if (data->swap < 0)
 262                                         error = -ENODEV;
 263                         } else {
 264                                 data->swap = -1;
 265                                 error = -EINVAL;
 266                         }
 267                 } else {
 268                         error = -EPERM;
 269                 }
 270                 break;
 271
 272         default:
 273                 error = -ENOTTY;
 274
 275         }
 276
 277         return error;
 278 }
 279
 280 static struct file_operations snapshot_fops = {
 281         .open = snapshot_open,
 282         .release = snapshot_release,
 283         .read = snapshot_read,
 284         .write = snapshot_write,
 285         .llseek = no_llseek,
 286         .ioctl = snapshot_ioctl,
 287 };
 288
 289 static struct miscdevice snapshot_device = {
 290         .minor = SNAPSHOT_MINOR,
 291         .name = "snapshot",
 292         .fops = &snapshot_fops,
 293 };
 294
 295 static int __init snapshot_device_init(void)
 296 {
 297         return misc_register(&snapshot_device);
 298 };
 299
 300 device_initcall(snapshot_device_init);