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 static bool need_wait;
  33
  34 #define SNAPSHOT_MINOR  231
  35
  36 static struct snapshot_data {
  37         struct snapshot_handle handle;
  38         int swap;
  39         int mode;
  40         bool frozen;
  41         bool ready;
  42         bool platform_support;
  43         bool free_bitmaps;
  44 } snapshot_state;
  45
  46 atomic_t snapshot_device_available = ATOMIC_INIT(1);
  47
  48 static int snapshot_open(struct inode *inode, struct file *filp)
  49 {
  50         struct snapshot_data *data;
  51         int error, nr_calls = 0;
  52
  53         if (!hibernation_available())
  54                 return -EPERM;
  55
  56         lock_system_sleep();
  57
  58         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
  59                 error = -EBUSY;
  60                 goto Unlock;
  61         }
  62
  63         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
  64                 atomic_inc(&snapshot_device_available);
  65                 error = -ENOSYS;
  66                 goto Unlock;
  67         }
  68         nonseekable_open(inode, filp);
  69         data = &snapshot_state;
  70         filp->private_data = data;
  71         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  72         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  73                 /* Hibernating.  The image device should be accessible. */
  74                 data->swap = swsusp_resume_device ?
  75                         swap_type_of(swsusp_resume_device, 0, NULL) : -1;
  76                 data->mode = O_RDONLY;
  77                 data->free_bitmaps = false;
  78                 error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
  79                 if (error)
  80                         __pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
  81         } else {
  82                 /*
  83                  * Resuming.  We may need to wait for the image device to
  84                  * appear.
  85                  */
  86                 need_wait = true;
  87
  88                 data->swap = -1;
  89                 data->mode = O_WRONLY;
  90                 error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
  91                 if (!error) {
  92                         error = create_basic_memory_bitmaps();
  93                         data->free_bitmaps = !error;
  94                 } else
  95                         nr_calls--;
  96
  97                 if (error)
  98                         __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
  99         }
 100         if (error)
 101                 atomic_inc(&snapshot_device_available);
 102
 103         data->frozen = false;
 104         data->ready = false;
 105         data->platform_support = false;
 106
 107  Unlock:
 108         unlock_system_sleep();
 109
 110         return error;
 111 }
 112
 113 static int snapshot_release(struct inode *inode, struct file *filp)
 114 {
 115         struct snapshot_data *data;
 116
 117         lock_system_sleep();
 118
 119         swsusp_free();
 120         data = filp->private_data;
 121         free_all_swap_pages(data->swap);
 122         if (data->frozen) {
 123                 pm_restore_gfp_mask();
 124                 free_basic_memory_bitmaps();
 125                 thaw_processes();
 126         } else if (data->free_bitmaps) {
 127                 free_basic_memory_bitmaps();
 128         }
 129         pm_notifier_call_chain(data->mode == O_RDONLY ?
 130                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 131         atomic_inc(&snapshot_device_available);
 132
 133         unlock_system_sleep();
 134
 135         return 0;
 136 }
 137
 138 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 139                              size_t count, loff_t *offp)
 140 {
 141         struct snapshot_data *data;
 142         ssize_t res;
 143         loff_t pg_offp = *offp & ~PAGE_MASK;
 144
 145         lock_system_sleep();
 146
 147         data = filp->private_data;
 148         if (!data->ready) {
 149                 res = -ENODATA;
 150                 goto Unlock;
 151         }
 152         if (!pg_offp) { /* on page boundary? */
 153                 res = snapshot_read_next(&data->handle);
 154                 if (res <= 0)
 155                         goto Unlock;
 156         } else {
 157                 res = PAGE_SIZE - pg_offp;
 158         }
 159
 160         res = simple_read_from_buffer(buf, count, &pg_offp,
 161                         data_of(data->handle), res);
 162         if (res > 0)
 163                 *offp += res;
 164
 165  Unlock:
 166         unlock_system_sleep();
 167
 168         return res;
 169 }
 170
 171 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 172                               size_t count, loff_t *offp)
 173 {
 174         struct snapshot_data *data;
 175         ssize_t res;
 176         loff_t pg_offp = *offp & ~PAGE_MASK;
 177
 178         if (need_wait) {
 179                 wait_for_device_probe();
 180                 need_wait = false;
 181         }
 182
 183         lock_system_sleep();
 184
 185         data = filp->private_data;
 186
 187         if (!pg_offp) {
 188                 res = snapshot_write_next(&data->handle);
 189                 if (res <= 0)
 190                         goto unlock;
 191         } else {
 192                 res = PAGE_SIZE - pg_offp;
 193         }
 194
 195         if (!data_of(data->handle)) {
 196                 res = -EINVAL;
 197                 goto unlock;
 198         }
 199
 200         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 201                         buf, count);
 202         if (res > 0)
 203                 *offp += res;
 204 unlock:
 205         unlock_system_sleep();
 206
 207         return res;
 208 }
 209
 210 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 211                                                         unsigned long arg)
 212 {
 213         int error = 0;
 214         struct snapshot_data *data;
 215         loff_t size;
 216         sector_t offset;
 217
 218         if (need_wait) {
 219                 wait_for_device_probe();
 220                 need_wait = false;
 221         }
 222
 223         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 224                 return -ENOTTY;
 225         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 226                 return -ENOTTY;
 227         if (!capable(CAP_SYS_ADMIN))
 228                 return -EPERM;
 229
 230         if (!mutex_trylock(&system_transition_mutex))
 231                 return -EBUSY;
 232
 233         lock_device_hotplug();
 234         data = filp->private_data;
 235
 236         switch (cmd) {
 237
 238         case SNAPSHOT_FREEZE:
 239                 if (data->frozen)
 240                         break;
 241
 242                 printk("Syncing filesystems ... ");
 243                 ksys_sync();
 244                 printk("done.\n");
 245
 246                 error = freeze_processes();
 247                 if (error)
 248                         break;
 249
 250                 error = create_basic_memory_bitmaps();
 251                 if (error)
 252                         thaw_processes();
 253                 else
 254                         data->frozen = true;
 255
 256                 break;
 257
 258         case SNAPSHOT_UNFREEZE:
 259                 if (!data->frozen || data->ready)
 260                         break;
 261                 pm_restore_gfp_mask();
 262                 free_basic_memory_bitmaps();
 263                 data->free_bitmaps = false;
 264                 thaw_processes();
 265                 data->frozen = false;
 266                 break;
 267
 268         case SNAPSHOT_CREATE_IMAGE:
 269                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 270                         error = -EPERM;
 271                         break;
 272                 }
 273                 pm_restore_gfp_mask();
 274                 error = hibernation_snapshot(data->platform_support);
 275                 if (!error) {
 276                         error = put_user(in_suspend, (int __user *)arg);
 277                         data->ready = !freezer_test_done && !error;
 278                         freezer_test_done = false;
 279                 }
 280                 break;
 281
 282         case SNAPSHOT_ATOMIC_RESTORE:
 283                 snapshot_write_finalize(&data->handle);
 284                 if (data->mode != O_WRONLY || !data->frozen ||
 285                     !snapshot_image_loaded(&data->handle)) {
 286                         error = -EPERM;
 287                         break;
 288                 }
 289                 error = hibernation_restore(data->platform_support);
 290                 break;
 291
 292         case SNAPSHOT_FREE:
 293                 swsusp_free();
 294                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 295                 data->ready = false;
 296                 /*
 297                  * It is necessary to thaw kernel threads here, because
 298                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 299                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 300                  * thawed, the preallocation of memory carried out by
 301                  * hibernation_snapshot() might run into problems (i.e. it
 302                  * might fail or even deadlock).
 303                  */
 304                 thaw_kernel_threads();
 305                 break;
 306
 307         case SNAPSHOT_PREF_IMAGE_SIZE:
 308                 image_size = arg;
 309                 break;
 310
 311         case SNAPSHOT_GET_IMAGE_SIZE:
 312                 if (!data->ready) {
 313                         error = -ENODATA;
 314                         break;
 315                 }
 316                 size = snapshot_get_image_size();
 317                 size <<= PAGE_SHIFT;
 318                 error = put_user(size, (loff_t __user *)arg);
 319                 break;
 320
 321         case SNAPSHOT_AVAIL_SWAP_SIZE:
 322                 size = count_swap_pages(data->swap, 1);
 323                 size <<= PAGE_SHIFT;
 324                 error = put_user(size, (loff_t __user *)arg);
 325                 break;
 326
 327         case SNAPSHOT_ALLOC_SWAP_PAGE:
 328                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 329                         error = -ENODEV;
 330                         break;
 331                 }
 332                 offset = alloc_swapdev_block(data->swap);
 333                 if (offset) {
 334                         offset <<= PAGE_SHIFT;
 335                         error = put_user(offset, (loff_t __user *)arg);
 336                 } else {
 337                         error = -ENOSPC;
 338                 }
 339                 break;
 340
 341         case SNAPSHOT_FREE_SWAP_PAGES:
 342                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 343                         error = -ENODEV;
 344                         break;
 345                 }
 346                 free_all_swap_pages(data->swap);
 347                 break;
 348
 349         case SNAPSHOT_S2RAM:
 350                 if (!data->frozen) {
 351                         error = -EPERM;
 352                         break;
 353                 }
 354                 /*
 355                  * Tasks are frozen and the notifiers have been called with
 356                  * PM_HIBERNATION_PREPARE
 357                  */
 358                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 359                 data->ready = false;
 360                 break;
 361
 362         case SNAPSHOT_PLATFORM_SUPPORT:
 363                 data->platform_support = !!arg;
 364                 break;
 365
 366         case SNAPSHOT_POWER_OFF:
 367                 if (data->platform_support)
 368                         error = hibernation_platform_enter();
 369                 break;
 370
 371         case SNAPSHOT_SET_SWAP_AREA:
 372                 if (swsusp_swap_in_use()) {
 373                         error = -EPERM;
 374                 } else {
 375                         struct resume_swap_area swap_area;
 376                         dev_t swdev;
 377
 378                         error = copy_from_user(&swap_area, (void __user *)arg,
 379                                         sizeof(struct resume_swap_area));
 380                         if (error) {
 381                                 error = -EFAULT;
 382                                 break;
 383                         }
 384
 385                         /*
 386                          * User space encodes device types as two-byte values,
 387                          * so we need to recode them
 388                          */
 389                         swdev = new_decode_dev(swap_area.dev);
 390                         if (swdev) {
 391                                 offset = swap_area.offset;
 392                                 data->swap = swap_type_of(swdev, offset, NULL);
 393                                 if (data->swap < 0)
 394                                         error = -ENODEV;
 395                         } else {
 396                                 data->swap = -1;
 397                                 error = -EINVAL;
 398                         }
 399                 }
 400                 break;
 401
 402         default:
 403                 error = -ENOTTY;
 404
 405         }
 406
 407         unlock_device_hotplug();
 408         mutex_unlock(&system_transition_mutex);
 409
 410         return error;
 411 }
 412
 413 #ifdef CONFIG_COMPAT
 414
 415 struct compat_resume_swap_area {
 416         compat_loff_t offset;
 417         u32 dev;
 418 } __packed;
 419
 420 static long
 421 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 422 {
 423         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 424
 425         switch (cmd) {
 426         case SNAPSHOT_GET_IMAGE_SIZE:
 427         case SNAPSHOT_AVAIL_SWAP_SIZE:
 428         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 429                 compat_loff_t __user *uoffset = compat_ptr(arg);
 430                 loff_t offset;
 431                 mm_segment_t old_fs;
 432                 int err;
 433
 434                 old_fs = get_fs();
 435                 set_fs(KERNEL_DS);
 436                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 437                 set_fs(old_fs);
 438                 if (!err && put_user(offset, uoffset))
 439                         err = -EFAULT;
 440                 return err;
 441         }
 442
 443         case SNAPSHOT_CREATE_IMAGE:
 444                 return snapshot_ioctl(file, cmd,
 445                                       (unsigned long) compat_ptr(arg));
 446
 447         case SNAPSHOT_SET_SWAP_AREA: {
 448                 struct compat_resume_swap_area __user *u_swap_area =
 449                         compat_ptr(arg);
 450                 struct resume_swap_area swap_area;
 451                 mm_segment_t old_fs;
 452                 int err;
 453
 454                 err = get_user(swap_area.offset, &u_swap_area->offset);
 455                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 456                 if (err)
 457                         return -EFAULT;
 458                 old_fs = get_fs();
 459                 set_fs(KERNEL_DS);
 460                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 461                                      (unsigned long) &swap_area);
 462                 set_fs(old_fs);
 463                 return err;
 464         }
 465
 466         default:
 467                 return snapshot_ioctl(file, cmd, arg);
 468         }
 469 }
 470
 471 #endif /* CONFIG_COMPAT */
 472
 473 static const struct file_operations snapshot_fops = {
 474         .open = snapshot_open,
 475         .release = snapshot_release,
 476         .read = snapshot_read,
 477         .write = snapshot_write,
 478         .llseek = no_llseek,
 479         .unlocked_ioctl = snapshot_ioctl,
 480 #ifdef CONFIG_COMPAT
 481         .compat_ioctl = snapshot_compat_ioctl,
 482 #endif
 483 };
 484
 485 static struct miscdevice snapshot_device = {
 486         .minor = SNAPSHOT_MINOR,
 487         .name = "snapshot",
 488         .fops = &snapshot_fops,
 489 };
 490
 491 static int __init snapshot_device_init(void)
 492 {
 493         return misc_register(&snapshot_device);
 494 };
 495
 496 device_initcall(snapshot_device_init);