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