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
  28 #include <asm/uaccess.h>
  29
  30 #include "power.h"
  31
  32
  33 #define SNAPSHOT_MINOR  231
  34
  35 static struct snapshot_data {
  36         struct snapshot_handle handle;
  37         int swap;
  38         int mode;
  39         bool frozen;
  40         bool ready;
  41         bool platform_support;
  42         bool free_bitmaps;
  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         if (!hibernation_available())
  53                 return -EPERM;
  54
  55         lock_system_sleep();
  56
  57         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
  58                 error = -EBUSY;
  59                 goto Unlock;
  60         }
  61
  62         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
  63                 atomic_inc(&snapshot_device_available);
  64                 error = -ENOSYS;
  65                 goto Unlock;
  66         }
  67         nonseekable_open(inode, filp);
  68         data = &snapshot_state;
  69         filp->private_data = data;
  70         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  71         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  72                 /* Hibernating.  The image device should be accessible. */
  73                 data->swap = swsusp_resume_device ?
  74                         swap_type_of(swsusp_resume_device, 0, NULL) : -1;
  75                 data->mode = O_RDONLY;
  76                 data->free_bitmaps = false;
  77                 error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
  78                 if (error)
  79                         pm_notifier_call_chain(PM_POST_HIBERNATION);
  80         } else {
  81                 /*
  82                  * Resuming.  We may need to wait for the image device to
  83                  * appear.
  84                  */
  85                 wait_for_device_probe();
  86
  87                 data->swap = -1;
  88                 data->mode = O_WRONLY;
  89                 error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
  90                 if (!error) {
  91                         error = create_basic_memory_bitmaps();
  92                         data->free_bitmaps = !error;
  93                 }
  94                 if (error)
  95                         pm_notifier_call_chain(PM_POST_RESTORE);
  96         }
  97         if (error)
  98                 atomic_inc(&snapshot_device_available);
  99
 100         data->frozen = false;
 101         data->ready = false;
 102         data->platform_support = false;
 103
 104  Unlock:
 105         unlock_system_sleep();
 106
 107         return error;
 108 }
 109
 110 static int snapshot_release(struct inode *inode, struct file *filp)
 111 {
 112         struct snapshot_data *data;
 113
 114         lock_system_sleep();
 115
 116         swsusp_free();
 117         data = filp->private_data;
 118         free_all_swap_pages(data->swap);
 119         if (data->frozen) {
 120                 pm_restore_gfp_mask();
 121                 free_basic_memory_bitmaps();
 122                 thaw_processes();
 123         } else if (data->free_bitmaps) {
 124                 free_basic_memory_bitmaps();
 125         }
 126         pm_notifier_call_chain(data->mode == O_RDONLY ?
 127                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 128         atomic_inc(&snapshot_device_available);
 129
 130         unlock_system_sleep();
 131
 132         return 0;
 133 }
 134
 135 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 136                              size_t count, loff_t *offp)
 137 {
 138         struct snapshot_data *data;
 139         ssize_t res;
 140         loff_t pg_offp = *offp & ~PAGE_MASK;
 141
 142         lock_system_sleep();
 143
 144         data = filp->private_data;
 145         if (!data->ready) {
 146                 res = -ENODATA;
 147                 goto Unlock;
 148         }
 149         if (!pg_offp) { /* on page boundary? */
 150                 res = snapshot_read_next(&data->handle);
 151                 if (res <= 0)
 152                         goto Unlock;
 153         } else {
 154                 res = PAGE_SIZE - pg_offp;
 155         }
 156
 157         res = simple_read_from_buffer(buf, count, &pg_offp,
 158                         data_of(data->handle), res);
 159         if (res > 0)
 160                 *offp += res;
 161
 162  Unlock:
 163         unlock_system_sleep();
 164
 165         return res;
 166 }
 167
 168 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 169                               size_t count, loff_t *offp)
 170 {
 171         struct snapshot_data *data;
 172         ssize_t res;
 173         loff_t pg_offp = *offp & ~PAGE_MASK;
 174
 175         lock_system_sleep();
 176
 177         data = filp->private_data;
 178
 179         if (!pg_offp) {
 180                 res = snapshot_write_next(&data->handle);
 181                 if (res <= 0)
 182                         goto unlock;
 183         } else {
 184                 res = PAGE_SIZE - pg_offp;
 185         }
 186
 187         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 188                         buf, count);
 189         if (res > 0)
 190                 *offp += res;
 191 unlock:
 192         unlock_system_sleep();
 193
 194         return res;
 195 }
 196
 197 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 198                                                         unsigned long arg)
 199 {
 200         int error = 0;
 201         struct snapshot_data *data;
 202         loff_t size;
 203         sector_t offset;
 204
 205         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 206                 return -ENOTTY;
 207         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 208                 return -ENOTTY;
 209         if (!capable(CAP_SYS_ADMIN))
 210                 return -EPERM;
 211
 212         if (!mutex_trylock(&pm_mutex))
 213                 return -EBUSY;
 214
 215         lock_device_hotplug();
 216         data = filp->private_data;
 217
 218         switch (cmd) {
 219
 220         case SNAPSHOT_FREEZE:
 221                 if (data->frozen)
 222                         break;
 223
 224                 printk("Syncing filesystems ... ");
 225                 sys_sync();
 226                 printk("done.\n");
 227
 228                 error = freeze_processes();
 229                 if (error)
 230                         break;
 231
 232                 error = create_basic_memory_bitmaps();
 233                 if (error)
 234                         thaw_processes();
 235                 else
 236                         data->frozen = true;
 237
 238                 break;
 239
 240         case SNAPSHOT_UNFREEZE:
 241                 if (!data->frozen || data->ready)
 242                         break;
 243                 pm_restore_gfp_mask();
 244                 free_basic_memory_bitmaps();
 245                 data->free_bitmaps = false;
 246                 thaw_processes();
 247                 data->frozen = false;
 248                 break;
 249
 250         case SNAPSHOT_CREATE_IMAGE:
 251                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 252                         error = -EPERM;
 253                         break;
 254                 }
 255                 pm_restore_gfp_mask();
 256                 error = hibernation_snapshot(data->platform_support);
 257                 if (!error) {
 258                         error = put_user(in_suspend, (int __user *)arg);
 259                         data->ready = !freezer_test_done && !error;
 260                         freezer_test_done = false;
 261                 }
 262                 break;
 263
 264         case SNAPSHOT_ATOMIC_RESTORE:
 265                 snapshot_write_finalize(&data->handle);
 266                 if (data->mode != O_WRONLY || !data->frozen ||
 267                     !snapshot_image_loaded(&data->handle)) {
 268                         error = -EPERM;
 269                         break;
 270                 }
 271                 error = hibernation_restore(data->platform_support);
 272                 break;
 273
 274         case SNAPSHOT_FREE:
 275                 swsusp_free();
 276                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 277                 data->ready = false;
 278                 /*
 279                  * It is necessary to thaw kernel threads here, because
 280                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 281                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 282                  * thawed, the preallocation of memory carried out by
 283                  * hibernation_snapshot() might run into problems (i.e. it
 284                  * might fail or even deadlock).
 285                  */
 286                 thaw_kernel_threads();
 287                 break;
 288
 289         case SNAPSHOT_PREF_IMAGE_SIZE:
 290                 image_size = arg;
 291                 break;
 292
 293         case SNAPSHOT_GET_IMAGE_SIZE:
 294                 if (!data->ready) {
 295                         error = -ENODATA;
 296                         break;
 297                 }
 298                 size = snapshot_get_image_size();
 299                 size <<= PAGE_SHIFT;
 300                 error = put_user(size, (loff_t __user *)arg);
 301                 break;
 302
 303         case SNAPSHOT_AVAIL_SWAP_SIZE:
 304                 size = count_swap_pages(data->swap, 1);
 305                 size <<= PAGE_SHIFT;
 306                 error = put_user(size, (loff_t __user *)arg);
 307                 break;
 308
 309         case SNAPSHOT_ALLOC_SWAP_PAGE:
 310                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 311                         error = -ENODEV;
 312                         break;
 313                 }
 314                 offset = alloc_swapdev_block(data->swap);
 315                 if (offset) {
 316                         offset <<= PAGE_SHIFT;
 317                         error = put_user(offset, (loff_t __user *)arg);
 318                 } else {
 319                         error = -ENOSPC;
 320                 }
 321                 break;
 322
 323         case SNAPSHOT_FREE_SWAP_PAGES:
 324                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 325                         error = -ENODEV;
 326                         break;
 327                 }
 328                 free_all_swap_pages(data->swap);
 329                 break;
 330
 331         case SNAPSHOT_S2RAM:
 332                 if (!data->frozen) {
 333                         error = -EPERM;
 334                         break;
 335                 }
 336                 /*
 337                  * Tasks are frozen and the notifiers have been called with
 338                  * PM_HIBERNATION_PREPARE
 339                  */
 340                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 341                 data->ready = false;
 342                 break;
 343
 344         case SNAPSHOT_PLATFORM_SUPPORT:
 345                 data->platform_support = !!arg;
 346                 break;
 347
 348         case SNAPSHOT_POWER_OFF:
 349                 if (data->platform_support)
 350                         error = hibernation_platform_enter();
 351                 break;
 352
 353         case SNAPSHOT_SET_SWAP_AREA:
 354                 if (swsusp_swap_in_use()) {
 355                         error = -EPERM;
 356                 } else {
 357                         struct resume_swap_area swap_area;
 358                         dev_t swdev;
 359
 360                         error = copy_from_user(&swap_area, (void __user *)arg,
 361                                         sizeof(struct resume_swap_area));
 362                         if (error) {
 363                                 error = -EFAULT;
 364                                 break;
 365                         }
 366
 367                         /*
 368                          * User space encodes device types as two-byte values,
 369                          * so we need to recode them
 370                          */
 371                         swdev = new_decode_dev(swap_area.dev);
 372                         if (swdev) {
 373                                 offset = swap_area.offset;
 374                                 data->swap = swap_type_of(swdev, offset, NULL);
 375                                 if (data->swap < 0)
 376                                         error = -ENODEV;
 377                         } else {
 378                                 data->swap = -1;
 379                                 error = -EINVAL;
 380                         }
 381                 }
 382                 break;
 383
 384         default:
 385                 error = -ENOTTY;
 386
 387         }
 388
 389         unlock_device_hotplug();
 390         mutex_unlock(&pm_mutex);
 391
 392         return error;
 393 }
 394
 395 #ifdef CONFIG_COMPAT
 396
 397 struct compat_resume_swap_area {
 398         compat_loff_t offset;
 399         u32 dev;
 400 } __packed;
 401
 402 static long
 403 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 404 {
 405         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 406
 407         switch (cmd) {
 408         case SNAPSHOT_GET_IMAGE_SIZE:
 409         case SNAPSHOT_AVAIL_SWAP_SIZE:
 410         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 411                 compat_loff_t __user *uoffset = compat_ptr(arg);
 412                 loff_t offset;
 413                 mm_segment_t old_fs;
 414                 int err;
 415
 416                 old_fs = get_fs();
 417                 set_fs(KERNEL_DS);
 418                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 419                 set_fs(old_fs);
 420                 if (!err && put_user(offset, uoffset))
 421                         err = -EFAULT;
 422                 return err;
 423         }
 424
 425         case SNAPSHOT_CREATE_IMAGE:
 426                 return snapshot_ioctl(file, cmd,
 427                                       (unsigned long) compat_ptr(arg));
 428
 429         case SNAPSHOT_SET_SWAP_AREA: {
 430                 struct compat_resume_swap_area __user *u_swap_area =
 431                         compat_ptr(arg);
 432                 struct resume_swap_area swap_area;
 433                 mm_segment_t old_fs;
 434                 int err;
 435
 436                 err = get_user(swap_area.offset, &u_swap_area->offset);
 437                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 438                 if (err)
 439                         return -EFAULT;
 440                 old_fs = get_fs();
 441                 set_fs(KERNEL_DS);
 442                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 443                                      (unsigned long) &swap_area);
 444                 set_fs(old_fs);
 445                 return err;
 446         }
 447
 448         default:
 449                 return snapshot_ioctl(file, cmd, arg);
 450         }
 451 }
 452
 453 #endif /* CONFIG_COMPAT */
 454
 455 static const struct file_operations snapshot_fops = {
 456         .open = snapshot_open,
 457         .release = snapshot_release,
 458         .read = snapshot_read,
 459         .write = snapshot_write,
 460         .llseek = no_llseek,
 461         .unlocked_ioctl = snapshot_ioctl,
 462 #ifdef CONFIG_COMPAT
 463         .compat_ioctl = snapshot_compat_ioctl,
 464 #endif
 465 };
 466
 467 static struct miscdevice snapshot_device = {
 468         .minor = SNAPSHOT_MINOR,
 469         .name = "snapshot",
 470         .fops = &snapshot_fops,
 471 };
 472
 473 static int __init snapshot_device_init(void)
 474 {
 475         return misc_register(&snapshot_device);
 476 };
 477
 478 device_initcall(snapshot_device_init);