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 <linux/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, nr_calls = 0;
  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, -1, &nr_calls);
  78                 if (error)
  79                         __pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
  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, -1, &nr_calls);
  90                 if (!error) {
  91                         error = create_basic_memory_bitmaps();
  92                         data->free_bitmaps = !error;
  93                 } else
  94                         nr_calls--;
  95
  96                 if (error)
  97                         __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
  98         }
  99         if (error)
 100                 atomic_inc(&snapshot_device_available);
 101
 102         data->frozen = false;
 103         data->ready = false;
 104         data->platform_support = false;
 105
 106  Unlock:
 107         unlock_system_sleep();
 108
 109         return error;
 110 }
 111
 112 static int snapshot_release(struct inode *inode, struct file *filp)
 113 {
 114         struct snapshot_data *data;
 115
 116         lock_system_sleep();
 117
 118         swsusp_free();
 119         data = filp->private_data;
 120         free_all_swap_pages(data->swap);
 121         if (data->frozen) {
 122                 pm_restore_gfp_mask();
 123                 free_basic_memory_bitmaps();
 124                 thaw_processes();
 125         } else if (data->free_bitmaps) {
 126                 free_basic_memory_bitmaps();
 127         }
 128         pm_notifier_call_chain(data->mode == O_RDONLY ?
 129                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 130         atomic_inc(&snapshot_device_available);
 131
 132         unlock_system_sleep();
 133
 134         return 0;
 135 }
 136
 137 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 138                              size_t count, loff_t *offp)
 139 {
 140         struct snapshot_data *data;
 141         ssize_t res;
 142         loff_t pg_offp = *offp & ~PAGE_MASK;
 143
 144         lock_system_sleep();
 145
 146         data = filp->private_data;
 147         if (!data->ready) {
 148                 res = -ENODATA;
 149                 goto Unlock;
 150         }
 151         if (!pg_offp) { /* on page boundary? */
 152                 res = snapshot_read_next(&data->handle);
 153                 if (res <= 0)
 154                         goto Unlock;
 155         } else {
 156                 res = PAGE_SIZE - pg_offp;
 157         }
 158
 159         res = simple_read_from_buffer(buf, count, &pg_offp,
 160                         data_of(data->handle), res);
 161         if (res > 0)
 162                 *offp += res;
 163
 164  Unlock:
 165         unlock_system_sleep();
 166
 167         return res;
 168 }
 169
 170 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 171                               size_t count, loff_t *offp)
 172 {
 173         struct snapshot_data *data;
 174         ssize_t res;
 175         loff_t pg_offp = *offp & ~PAGE_MASK;
 176
 177         lock_system_sleep();
 178
 179         data = filp->private_data;
 180
 181         if (!pg_offp) {
 182                 res = snapshot_write_next(&data->handle);
 183                 if (res <= 0)
 184                         goto unlock;
 185         } else {
 186                 res = PAGE_SIZE - pg_offp;
 187         }
 188
 189         if (!data_of(data->handle)) {
 190                 res = -EINVAL;
 191                 goto unlock;
 192         }
 193
 194         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 195                         buf, count);
 196         if (res > 0)
 197                 *offp += res;
 198 unlock:
 199         unlock_system_sleep();
 200
 201         return res;
 202 }
 203
 204 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 205                                                         unsigned long arg)
 206 {
 207         int error = 0;
 208         struct snapshot_data *data;
 209         loff_t size;
 210         sector_t offset;
 211
 212         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 213                 return -ENOTTY;
 214         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 215                 return -ENOTTY;
 216         if (!capable(CAP_SYS_ADMIN))
 217                 return -EPERM;
 218
 219         if (!mutex_trylock(&system_transition_mutex))
 220                 return -EBUSY;
 221
 222         lock_device_hotplug();
 223         data = filp->private_data;
 224
 225         switch (cmd) {
 226
 227         case SNAPSHOT_FREEZE:
 228                 if (data->frozen)
 229                         break;
 230
 231                 printk("Syncing filesystems ... ");
 232                 ksys_sync();
 233                 printk("done.\n");
 234
 235                 error = freeze_processes();
 236                 if (error)
 237                         break;
 238
 239                 error = create_basic_memory_bitmaps();
 240                 if (error)
 241                         thaw_processes();
 242                 else
 243                         data->frozen = true;
 244
 245                 break;
 246
 247         case SNAPSHOT_UNFREEZE:
 248                 if (!data->frozen || data->ready)
 249                         break;
 250                 pm_restore_gfp_mask();
 251                 free_basic_memory_bitmaps();
 252                 data->free_bitmaps = false;
 253                 thaw_processes();
 254                 data->frozen = false;
 255                 break;
 256
 257         case SNAPSHOT_CREATE_IMAGE:
 258                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 259                         error = -EPERM;
 260                         break;
 261                 }
 262                 pm_restore_gfp_mask();
 263                 error = hibernation_snapshot(data->platform_support);
 264                 if (!error) {
 265                         error = put_user(in_suspend, (int __user *)arg);
 266                         data->ready = !freezer_test_done && !error;
 267                         freezer_test_done = false;
 268                 }
 269                 break;
 270
 271         case SNAPSHOT_ATOMIC_RESTORE:
 272                 snapshot_write_finalize(&data->handle);
 273                 if (data->mode != O_WRONLY || !data->frozen ||
 274                     !snapshot_image_loaded(&data->handle)) {
 275                         error = -EPERM;
 276                         break;
 277                 }
 278                 error = hibernation_restore(data->platform_support);
 279                 break;
 280
 281         case SNAPSHOT_FREE:
 282                 swsusp_free();
 283                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 284                 data->ready = false;
 285                 /*
 286                  * It is necessary to thaw kernel threads here, because
 287                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 288                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 289                  * thawed, the preallocation of memory carried out by
 290                  * hibernation_snapshot() might run into problems (i.e. it
 291                  * might fail or even deadlock).
 292                  */
 293                 thaw_kernel_threads();
 294                 break;
 295
 296         case SNAPSHOT_PREF_IMAGE_SIZE:
 297                 image_size = arg;
 298                 break;
 299
 300         case SNAPSHOT_GET_IMAGE_SIZE:
 301                 if (!data->ready) {
 302                         error = -ENODATA;
 303                         break;
 304                 }
 305                 size = snapshot_get_image_size();
 306                 size <<= PAGE_SHIFT;
 307                 error = put_user(size, (loff_t __user *)arg);
 308                 break;
 309
 310         case SNAPSHOT_AVAIL_SWAP_SIZE:
 311                 size = count_swap_pages(data->swap, 1);
 312                 size <<= PAGE_SHIFT;
 313                 error = put_user(size, (loff_t __user *)arg);
 314                 break;
 315
 316         case SNAPSHOT_ALLOC_SWAP_PAGE:
 317                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 318                         error = -ENODEV;
 319                         break;
 320                 }
 321                 offset = alloc_swapdev_block(data->swap);
 322                 if (offset) {
 323                         offset <<= PAGE_SHIFT;
 324                         error = put_user(offset, (loff_t __user *)arg);
 325                 } else {
 326                         error = -ENOSPC;
 327                 }
 328                 break;
 329
 330         case SNAPSHOT_FREE_SWAP_PAGES:
 331                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 332                         error = -ENODEV;
 333                         break;
 334                 }
 335                 free_all_swap_pages(data->swap);
 336                 break;
 337
 338         case SNAPSHOT_S2RAM:
 339                 if (!data->frozen) {
 340                         error = -EPERM;
 341                         break;
 342                 }
 343                 /*
 344                  * Tasks are frozen and the notifiers have been called with
 345                  * PM_HIBERNATION_PREPARE
 346                  */
 347                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 348                 data->ready = false;
 349                 break;
 350
 351         case SNAPSHOT_PLATFORM_SUPPORT:
 352                 data->platform_support = !!arg;
 353                 break;
 354
 355         case SNAPSHOT_POWER_OFF:
 356                 if (data->platform_support)
 357                         error = hibernation_platform_enter();
 358                 break;
 359
 360         case SNAPSHOT_SET_SWAP_AREA:
 361                 if (swsusp_swap_in_use()) {
 362                         error = -EPERM;
 363                 } else {
 364                         struct resume_swap_area swap_area;
 365                         dev_t swdev;
 366
 367                         error = copy_from_user(&swap_area, (void __user *)arg,
 368                                         sizeof(struct resume_swap_area));
 369                         if (error) {
 370                                 error = -EFAULT;
 371                                 break;
 372                         }
 373
 374                         /*
 375                          * User space encodes device types as two-byte values,
 376                          * so we need to recode them
 377                          */
 378                         swdev = new_decode_dev(swap_area.dev);
 379                         if (swdev) {
 380                                 offset = swap_area.offset;
 381                                 data->swap = swap_type_of(swdev, offset, NULL);
 382                                 if (data->swap < 0)
 383                                         error = -ENODEV;
 384                         } else {
 385                                 data->swap = -1;
 386                                 error = -EINVAL;
 387                         }
 388                 }
 389                 break;
 390
 391         default:
 392                 error = -ENOTTY;
 393
 394         }
 395
 396         unlock_device_hotplug();
 397         mutex_unlock(&system_transition_mutex);
 398
 399         return error;
 400 }
 401
 402 #ifdef CONFIG_COMPAT
 403
 404 struct compat_resume_swap_area {
 405         compat_loff_t offset;
 406         u32 dev;
 407 } __packed;
 408
 409 static long
 410 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 411 {
 412         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 413
 414         switch (cmd) {
 415         case SNAPSHOT_GET_IMAGE_SIZE:
 416         case SNAPSHOT_AVAIL_SWAP_SIZE:
 417         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 418                 compat_loff_t __user *uoffset = compat_ptr(arg);
 419                 loff_t offset;
 420                 mm_segment_t old_fs;
 421                 int err;
 422
 423                 old_fs = get_fs();
 424                 set_fs(KERNEL_DS);
 425                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 426                 set_fs(old_fs);
 427                 if (!err && put_user(offset, uoffset))
 428                         err = -EFAULT;
 429                 return err;
 430         }
 431
 432         case SNAPSHOT_CREATE_IMAGE:
 433                 return snapshot_ioctl(file, cmd,
 434                                       (unsigned long) compat_ptr(arg));
 435
 436         case SNAPSHOT_SET_SWAP_AREA: {
 437                 struct compat_resume_swap_area __user *u_swap_area =
 438                         compat_ptr(arg);
 439                 struct resume_swap_area swap_area;
 440                 mm_segment_t old_fs;
 441                 int err;
 442
 443                 err = get_user(swap_area.offset, &u_swap_area->offset);
 444                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 445                 if (err)
 446                         return -EFAULT;
 447                 old_fs = get_fs();
 448                 set_fs(KERNEL_DS);
 449                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 450                                      (unsigned long) &swap_area);
 451                 set_fs(old_fs);
 452                 return err;
 453         }
 454
 455         default:
 456                 return snapshot_ioctl(file, cmd, arg);
 457         }
 458 }
 459
 460 #endif /* CONFIG_COMPAT */
 461
 462 static const struct file_operations snapshot_fops = {
 463         .open = snapshot_open,
 464         .release = snapshot_release,
 465         .read = snapshot_read,
 466         .write = snapshot_write,
 467         .llseek = no_llseek,
 468         .unlocked_ioctl = snapshot_ioctl,
 469 #ifdef CONFIG_COMPAT
 470         .compat_ioctl = snapshot_compat_ioctl,
 471 #endif
 472 };
 473
 474 static struct miscdevice snapshot_device = {
 475         .minor = SNAPSHOT_MINOR,
 476         .name = "snapshot",
 477         .fops = &snapshot_fops,
 478 };
 479
 480 static int __init snapshot_device_init(void)
 481 {
 482         return misc_register(&snapshot_device);
 483 };
 484
 485 device_initcall(snapshot_device_init);