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