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, 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         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 190                         buf, count);
 191         if (res > 0)
 192                 *offp += res;
 193 unlock:
 194         unlock_system_sleep();
 195
 196         return res;
 197 }
 198
 199 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 200                                                         unsigned long arg)
 201 {
 202         int error = 0;
 203         struct snapshot_data *data;
 204         loff_t size;
 205         sector_t offset;
 206
 207         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 208                 return -ENOTTY;
 209         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 210                 return -ENOTTY;
 211         if (!capable(CAP_SYS_ADMIN))
 212                 return -EPERM;
 213
 214         if (!mutex_trylock(&pm_mutex))
 215                 return -EBUSY;
 216
 217         lock_device_hotplug();
 218         data = filp->private_data;
 219
 220         switch (cmd) {
 221
 222         case SNAPSHOT_FREEZE:
 223                 if (data->frozen)
 224                         break;
 225
 226                 printk("Syncing filesystems ... ");
 227                 sys_sync();
 228                 printk("done.\n");
 229
 230                 error = freeze_processes();
 231                 if (error)
 232                         break;
 233
 234                 error = create_basic_memory_bitmaps();
 235                 if (error)
 236                         thaw_processes();
 237                 else
 238                         data->frozen = true;
 239
 240                 break;
 241
 242         case SNAPSHOT_UNFREEZE:
 243                 if (!data->frozen || data->ready)
 244                         break;
 245                 pm_restore_gfp_mask();
 246                 free_basic_memory_bitmaps();
 247                 data->free_bitmaps = false;
 248                 thaw_processes();
 249                 data->frozen = false;
 250                 break;
 251
 252         case SNAPSHOT_CREATE_IMAGE:
 253                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 254                         error = -EPERM;
 255                         break;
 256                 }
 257                 pm_restore_gfp_mask();
 258                 error = hibernation_snapshot(data->platform_support);
 259                 if (!error) {
 260                         error = put_user(in_suspend, (int __user *)arg);
 261                         data->ready = !freezer_test_done && !error;
 262                         freezer_test_done = false;
 263                 }
 264                 break;
 265
 266         case SNAPSHOT_ATOMIC_RESTORE:
 267                 snapshot_write_finalize(&data->handle);
 268                 if (data->mode != O_WRONLY || !data->frozen ||
 269                     !snapshot_image_loaded(&data->handle)) {
 270                         error = -EPERM;
 271                         break;
 272                 }
 273                 error = hibernation_restore(data->platform_support);
 274                 break;
 275
 276         case SNAPSHOT_FREE:
 277                 swsusp_free();
 278                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 279                 data->ready = false;
 280                 /*
 281                  * It is necessary to thaw kernel threads here, because
 282                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 283                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 284                  * thawed, the preallocation of memory carried out by
 285                  * hibernation_snapshot() might run into problems (i.e. it
 286                  * might fail or even deadlock).
 287                  */
 288                 thaw_kernel_threads();
 289                 break;
 290
 291         case SNAPSHOT_PREF_IMAGE_SIZE:
 292                 image_size = arg;
 293                 break;
 294
 295         case SNAPSHOT_GET_IMAGE_SIZE:
 296                 if (!data->ready) {
 297                         error = -ENODATA;
 298                         break;
 299                 }
 300                 size = snapshot_get_image_size();
 301                 size <<= PAGE_SHIFT;
 302                 error = put_user(size, (loff_t __user *)arg);
 303                 break;
 304
 305         case SNAPSHOT_AVAIL_SWAP_SIZE:
 306                 size = count_swap_pages(data->swap, 1);
 307                 size <<= PAGE_SHIFT;
 308                 error = put_user(size, (loff_t __user *)arg);
 309                 break;
 310
 311         case SNAPSHOT_ALLOC_SWAP_PAGE:
 312                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 313                         error = -ENODEV;
 314                         break;
 315                 }
 316                 offset = alloc_swapdev_block(data->swap);
 317                 if (offset) {
 318                         offset <<= PAGE_SHIFT;
 319                         error = put_user(offset, (loff_t __user *)arg);
 320                 } else {
 321                         error = -ENOSPC;
 322                 }
 323                 break;
 324
 325         case SNAPSHOT_FREE_SWAP_PAGES:
 326                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 327                         error = -ENODEV;
 328                         break;
 329                 }
 330                 free_all_swap_pages(data->swap);
 331                 break;
 332
 333         case SNAPSHOT_S2RAM:
 334                 if (!data->frozen) {
 335                         error = -EPERM;
 336                         break;
 337                 }
 338                 /*
 339                  * Tasks are frozen and the notifiers have been called with
 340                  * PM_HIBERNATION_PREPARE
 341                  */
 342                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 343                 data->ready = false;
 344                 break;
 345
 346         case SNAPSHOT_PLATFORM_SUPPORT:
 347                 data->platform_support = !!arg;
 348                 break;
 349
 350         case SNAPSHOT_POWER_OFF:
 351                 if (data->platform_support)
 352                         error = hibernation_platform_enter();
 353                 break;
 354
 355         case SNAPSHOT_SET_SWAP_AREA:
 356                 if (swsusp_swap_in_use()) {
 357                         error = -EPERM;
 358                 } else {
 359                         struct resume_swap_area swap_area;
 360                         dev_t swdev;
 361
 362                         error = copy_from_user(&swap_area, (void __user *)arg,
 363                                         sizeof(struct resume_swap_area));
 364                         if (error) {
 365                                 error = -EFAULT;
 366                                 break;
 367                         }
 368
 369                         /*
 370                          * User space encodes device types as two-byte values,
 371                          * so we need to recode them
 372                          */
 373                         swdev = new_decode_dev(swap_area.dev);
 374                         if (swdev) {
 375                                 offset = swap_area.offset;
 376                                 data->swap = swap_type_of(swdev, offset, NULL);
 377                                 if (data->swap < 0)
 378                                         error = -ENODEV;
 379                         } else {
 380                                 data->swap = -1;
 381                                 error = -EINVAL;
 382                         }
 383                 }
 384                 break;
 385
 386         default:
 387                 error = -ENOTTY;
 388
 389         }
 390
 391         unlock_device_hotplug();
 392         mutex_unlock(&pm_mutex);
 393
 394         return error;
 395 }
 396
 397 #ifdef CONFIG_COMPAT
 398
 399 struct compat_resume_swap_area {
 400         compat_loff_t offset;
 401         u32 dev;
 402 } __packed;
 403
 404 static long
 405 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 406 {
 407         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 408
 409         switch (cmd) {
 410         case SNAPSHOT_GET_IMAGE_SIZE:
 411         case SNAPSHOT_AVAIL_SWAP_SIZE:
 412         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 413                 compat_loff_t __user *uoffset = compat_ptr(arg);
 414                 loff_t offset;
 415                 mm_segment_t old_fs;
 416                 int err;
 417
 418                 old_fs = get_fs();
 419                 set_fs(KERNEL_DS);
 420                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 421                 set_fs(old_fs);
 422                 if (!err && put_user(offset, uoffset))
 423                         err = -EFAULT;
 424                 return err;
 425         }
 426
 427         case SNAPSHOT_CREATE_IMAGE:
 428                 return snapshot_ioctl(file, cmd,
 429                                       (unsigned long) compat_ptr(arg));
 430
 431         case SNAPSHOT_SET_SWAP_AREA: {
 432                 struct compat_resume_swap_area __user *u_swap_area =
 433                         compat_ptr(arg);
 434                 struct resume_swap_area swap_area;
 435                 mm_segment_t old_fs;
 436                 int err;
 437
 438                 err = get_user(swap_area.offset, &u_swap_area->offset);
 439                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 440                 if (err)
 441                         return -EFAULT;
 442                 old_fs = get_fs();
 443                 set_fs(KERNEL_DS);
 444                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 445                                      (unsigned long) &swap_area);
 446                 set_fs(old_fs);
 447                 return err;
 448         }
 449
 450         default:
 451                 return snapshot_ioctl(file, cmd, arg);
 452         }
 453 }
 454
 455 #endif /* CONFIG_COMPAT */
 456
 457 static const struct file_operations snapshot_fops = {
 458         .open = snapshot_open,
 459         .release = snapshot_release,
 460         .read = snapshot_read,
 461         .write = snapshot_write,
 462         .llseek = no_llseek,
 463         .unlocked_ioctl = snapshot_ioctl,
 464 #ifdef CONFIG_COMPAT
 465         .compat_ioctl = snapshot_compat_ioctl,
 466 #endif
 467 };
 468
 469 static struct miscdevice snapshot_device = {
 470         .minor = SNAPSHOT_MINOR,
 471         .name = "snapshot",
 472         .fops = &snapshot_fops,
 473 };
 474
 475 static int __init snapshot_device_init(void)
 476 {
 477         return misc_register(&snapshot_device);
 478 };
 479
 480 device_initcall(snapshot_device_init);