kernel/power/user.c

   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/reboot.h>
  15 #include <linux/string.h>
  16 #include <linux/device.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/mm.h>
  19 #include <linux/swap.h>
  20 #include <linux/swapops.h>
  21 #include <linux/pm.h>
  22 #include <linux/fs.h>
  23 #include <linux/compat.h>
  24 #include <linux/console.h>
  25 #include <linux/cpu.h>
  26 #include <linux/freezer.h>
  27 #include <scsi/scsi_scan.h>
  28
  29 #include <asm/uaccess.h>
  30
  31 #include "power.h"
  32
  33
  34 #define SNAPSHOT_MINOR  231
  35
  36 static struct snapshot_data {
  37         struct snapshot_handle handle;
  38         int swap;
  39         int mode;
  40         char frozen;
  41         char ready;
  42         char platform_support;
  43 } snapshot_state;
  44
  45 atomic_t snapshot_device_available = ATOMIC_INIT(1);
  46
  47 static int snapshot_open(struct inode *inode, struct file *filp)
  48 {
  49         struct snapshot_data *data;
  50         int error;
  51
  52         lock_system_sleep();
  53
  54         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
  55                 error = -EBUSY;
  56                 goto Unlock;
  57         }
  58
  59         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
  60                 atomic_inc(&snapshot_device_available);
  61                 error = -ENOSYS;
  62                 goto Unlock;
  63         }
  64         if(create_basic_memory_bitmaps()) {
  65                 atomic_inc(&snapshot_device_available);
  66                 error = -ENOMEM;
  67                 goto Unlock;
  68         }
  69         nonseekable_open(inode, filp);
  70         data = &snapshot_state;
  71         filp->private_data = data;
  72         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  73         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  74                 /* Hibernating.  The image device should be accessible. */
  75                 data->swap = swsusp_resume_device ?
  76                         swap_type_of(swsusp_resume_device, 0, NULL) : -1;
  77                 data->mode = O_RDONLY;
  78                 error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
  79                 if (error)
  80                         pm_notifier_call_chain(PM_POST_HIBERNATION);
  81         } else {
  82                 /*
  83                  * Resuming.  We may need to wait for the image device to
  84                  * appear.
  85                  */
  86                 wait_for_device_probe();
  87                 scsi_complete_async_scans();
  88
  89                 data->swap = -1;
  90                 data->mode = O_WRONLY;
  91                 error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
  92                 if (error)
  93                         pm_notifier_call_chain(PM_POST_RESTORE);
  94         }
  95         if (error) {
  96                 free_basic_memory_bitmaps();
  97                 atomic_inc(&snapshot_device_available);
  98         }
  99         data->frozen = 0;
 100         data->ready = 0;
 101         data->platform_support = 0;
 102
 103  Unlock:
 104         unlock_system_sleep();
 105
 106         return error;
 107 }
 108
 109 static int snapshot_release(struct inode *inode, struct file *filp)
 110 {
 111         struct snapshot_data *data;
 112
 113         lock_system_sleep();
 114
 115         swsusp_free();
 116         free_basic_memory_bitmaps();
 117         data = filp->private_data;
 118         free_all_swap_pages(data->swap);
 119         if (data->frozen) {
 120                 pm_restore_gfp_mask();
 121                 thaw_processes();
 122         }
 123         pm_notifier_call_chain(data->mode == O_RDONLY ?
 124                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 125         atomic_inc(&snapshot_device_available);
 126
 127         unlock_system_sleep();
 128
 129         return 0;
 130 }
 131
 132 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 133                              size_t count, loff_t *offp)
 134 {
 135         struct snapshot_data *data;
 136         ssize_t res;
 137         loff_t pg_offp = *offp & ~PAGE_MASK;
 138
 139         lock_system_sleep();
 140
 141         data = filp->private_data;
 142         if (!data->ready) {
 143                 res = -ENODATA;
 144                 goto Unlock;
 145         }
 146         if (!pg_offp) { /* on page boundary? */
 147                 res = snapshot_read_next(&data->handle);
 148                 if (res <= 0)
 149                         goto Unlock;
 150         } else {
 151                 res = PAGE_SIZE - pg_offp;
 152         }
 153
 154         res = simple_read_from_buffer(buf, count, &pg_offp,
 155                         data_of(data->handle), res);
 156         if (res > 0)
 157                 *offp += res;
 158
 159  Unlock:
 160         unlock_system_sleep();
 161
 162         return res;
 163 }
 164
 165 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 166                               size_t count, loff_t *offp)
 167 {
 168         struct snapshot_data *data;
 169         ssize_t res;
 170         loff_t pg_offp = *offp & ~PAGE_MASK;
 171
 172         lock_system_sleep();
 173
 174         data = filp->private_data;
 175
 176         if (!pg_offp) {
 177                 res = snapshot_write_next(&data->handle);
 178                 if (res <= 0)
 179                         goto unlock;
 180         } else {
 181                 res = PAGE_SIZE - pg_offp;
 182         }
 183
 184         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 185                         buf, count);
 186         if (res > 0)
 187                 *offp += res;
 188 unlock:
 189         unlock_system_sleep();
 190
 191         return res;
 192 }
 193
 194 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 195                                                         unsigned long arg)
 196 {
 197         int error = 0;
 198         struct snapshot_data *data;
 199         loff_t size;
 200         sector_t offset;
 201
 202         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 203                 return -ENOTTY;
 204         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 205                 return -ENOTTY;
 206         if (!capable(CAP_SYS_ADMIN))
 207                 return -EPERM;
 208
 209         if (!mutex_trylock(&pm_mutex))
 210                 return -EBUSY;
 211
 212         data = filp->private_data;
 213
 214         switch (cmd) {
 215
 216         case SNAPSHOT_FREEZE:
 217                 if (data->frozen)
 218                         break;
 219
 220                 printk("Syncing filesystems ... ");
 221                 sys_sync();
 222                 printk("done.\n");
 223
 224                 error = freeze_processes();
 225                 if (!error)
 226                         data->frozen = 1;
 227                 break;
 228
 229         case SNAPSHOT_UNFREEZE:
 230                 if (!data->frozen || data->ready)
 231                         break;
 232                 pm_restore_gfp_mask();
 233                 thaw_processes();
 234                 data->frozen = 0;
 235                 break;
 236
 237         case SNAPSHOT_CREATE_IMAGE:
 238                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 239                         error = -EPERM;
 240                         break;
 241                 }
 242                 pm_restore_gfp_mask();
 243                 error = hibernation_snapshot(data->platform_support);
 244                 if (error) {
 245                         thaw_kernel_threads();
 246                 } else {
 247                         error = put_user(in_suspend, (int __user *)arg);
 248                         if (!error && !freezer_test_done)
 249                                 data->ready = 1;
 250                         if (freezer_test_done) {
 251                                 freezer_test_done = false;
 252                                 thaw_kernel_threads();
 253                         }
 254                 }
 255                 break;
 256
 257         case SNAPSHOT_ATOMIC_RESTORE:
 258                 snapshot_write_finalize(&data->handle);
 259                 if (data->mode != O_WRONLY || !data->frozen ||
 260                     !snapshot_image_loaded(&data->handle)) {
 261                         error = -EPERM;
 262                         break;
 263                 }
 264                 error = hibernation_restore(data->platform_support);
 265                 break;
 266
 267         case SNAPSHOT_FREE:
 268                 swsusp_free();
 269                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 270                 data->ready = 0;
 271                 /*
 272                  * It is necessary to thaw kernel threads here, because
 273                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 274                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 275                  * thawed, the preallocation of memory carried out by
 276                  * hibernation_snapshot() might run into problems (i.e. it
 277                  * might fail or even deadlock).
 278                  */
 279                 thaw_kernel_threads();
 280                 break;
 281
 282         case SNAPSHOT_PREF_IMAGE_SIZE:
 283                 image_size = arg;
 284                 break;
 285
 286         case SNAPSHOT_GET_IMAGE_SIZE:
 287                 if (!data->ready) {
 288                         error = -ENODATA;
 289                         break;
 290                 }
 291                 size = snapshot_get_image_size();
 292                 size <<= PAGE_SHIFT;
 293                 error = put_user(size, (loff_t __user *)arg);
 294                 break;
 295
 296         case SNAPSHOT_AVAIL_SWAP_SIZE:
 297                 size = count_swap_pages(data->swap, 1);
 298                 size <<= PAGE_SHIFT;
 299                 error = put_user(size, (loff_t __user *)arg);
 300                 break;
 301
 302         case SNAPSHOT_ALLOC_SWAP_PAGE:
 303                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 304                         error = -ENODEV;
 305                         break;
 306                 }
 307                 offset = alloc_swapdev_block(data->swap);
 308                 if (offset) {
 309                         offset <<= PAGE_SHIFT;
 310                         error = put_user(offset, (loff_t __user *)arg);
 311                 } else {
 312                         error = -ENOSPC;
 313                 }
 314                 break;
 315
 316         case SNAPSHOT_FREE_SWAP_PAGES:
 317                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 318                         error = -ENODEV;
 319                         break;
 320                 }
 321                 free_all_swap_pages(data->swap);
 322                 break;
 323
 324         case SNAPSHOT_S2RAM:
 325                 if (!data->frozen) {
 326                         error = -EPERM;
 327                         break;
 328                 }
 329                 /*
 330                  * Tasks are frozen and the notifiers have been called with
 331                  * PM_HIBERNATION_PREPARE
 332                  */
 333                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 334                 data->ready = 0;
 335                 break;
 336
 337         case SNAPSHOT_PLATFORM_SUPPORT:
 338                 data->platform_support = !!arg;
 339                 break;
 340
 341         case SNAPSHOT_POWER_OFF:
 342                 if (data->platform_support)
 343                         error = hibernation_platform_enter();
 344                 break;
 345
 346         case SNAPSHOT_SET_SWAP_AREA:
 347                 if (swsusp_swap_in_use()) {
 348                         error = -EPERM;
 349                 } else {
 350                         struct resume_swap_area swap_area;
 351                         dev_t swdev;
 352
 353                         error = copy_from_user(&swap_area, (void __user *)arg,
 354                                         sizeof(struct resume_swap_area));
 355                         if (error) {
 356                                 error = -EFAULT;
 357                                 break;
 358                         }
 359
 360                         /*
 361                          * User space encodes device types as two-byte values,
 362                          * so we need to recode them
 363                          */
 364                         swdev = new_decode_dev(swap_area.dev);
 365                         if (swdev) {
 366                                 offset = swap_area.offset;
 367                                 data->swap = swap_type_of(swdev, offset, NULL);
 368                                 if (data->swap < 0)
 369                                         error = -ENODEV;
 370                         } else {
 371                                 data->swap = -1;
 372                                 error = -EINVAL;
 373                         }
 374                 }
 375                 break;
 376
 377         default:
 378                 error = -ENOTTY;
 379
 380         }
 381
 382         mutex_unlock(&pm_mutex);
 383
 384         return error;
 385 }
 386
 387 #ifdef CONFIG_COMPAT
 388
 389 struct compat_resume_swap_area {
 390         compat_loff_t offset;
 391         u32 dev;
 392 } __packed;
 393
 394 static long
 395 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 396 {
 397         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 398
 399         switch (cmd) {
 400         case SNAPSHOT_GET_IMAGE_SIZE:
 401         case SNAPSHOT_AVAIL_SWAP_SIZE:
 402         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 403                 compat_loff_t __user *uoffset = compat_ptr(arg);
 404                 loff_t offset;
 405                 mm_segment_t old_fs;
 406                 int err;
 407
 408                 old_fs = get_fs();
 409                 set_fs(KERNEL_DS);
 410                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 411                 set_fs(old_fs);
 412                 if (!err && put_user(offset, uoffset))
 413                         err = -EFAULT;
 414                 return err;
 415         }
 416
 417         case SNAPSHOT_CREATE_IMAGE:
 418                 return snapshot_ioctl(file, cmd,
 419                                       (unsigned long) compat_ptr(arg));
 420
 421         case SNAPSHOT_SET_SWAP_AREA: {
 422                 struct compat_resume_swap_area __user *u_swap_area =
 423                         compat_ptr(arg);
 424                 struct resume_swap_area swap_area;
 425                 mm_segment_t old_fs;
 426                 int err;
 427
 428                 err = get_user(swap_area.offset, &u_swap_area->offset);
 429                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 430                 if (err)
 431                         return -EFAULT;
 432                 old_fs = get_fs();
 433                 set_fs(KERNEL_DS);
 434                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 435                                      (unsigned long) &swap_area);
 436                 set_fs(old_fs);
 437                 return err;
 438         }
 439
 440         default:
 441                 return snapshot_ioctl(file, cmd, arg);
 442         }
 443 }
 444
 445 #endif /* CONFIG_COMPAT */
 446
 447 static const struct file_operations snapshot_fops = {
 448         .open = snapshot_open,
 449         .release = snapshot_release,
 450         .read = snapshot_read,
 451         .write = snapshot_write,
 452         .llseek = no_llseek,
 453         .unlocked_ioctl = snapshot_ioctl,
 454 #ifdef CONFIG_COMPAT
 455         .compat_ioctl = snapshot_compat_ioctl,
 456 #endif
 457 };
 458
 459 static struct miscdevice snapshot_device = {
 460         .minor = SNAPSHOT_MINOR,
 461         .name = "snapshot",
 462         .fops = &snapshot_fops,
 463 };
 464
 465 static int __init snapshot_device_init(void)
 466 {
 467         return misc_register(&snapshot_device);
 468 };
 469
 470 device_initcall(snapshot_device_init);