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