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/export.h>
  16 #include <linux/string.h>
  17 #include <linux/device.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/mm.h>
  20 #include <linux/swap.h>
  21 #include <linux/swapops.h>
  22 #include <linux/pm.h>
  23 #include <linux/fs.h>
  24 #include <linux/compat.h>
  25 #include <linux/console.h>
  26 #include <linux/cpu.h>
  27 #include <linux/freezer.h>
  28
  29 #include <asm/uaccess.h>
  30
  31 #include "power.h"
  32
  33
  34 #define SNAPSHOT_MINOR  231
  35
  36 static struct snapshot_data {
  37         struct snapshot_handle handle;
  38         int swap;
  39         int mode;
  40         char frozen;
  41         char ready;
  42         char platform_support;
  43 } snapshot_state;
  44
  45 atomic_t snapshot_device_available = ATOMIC_INIT(1);
  46 EXPORT_SYMBOL_GPL(snapshot_device_available);
  47
  48 static int snapshot_open(struct inode *inode, struct file *filp)
  49 {
  50         struct snapshot_data *data;
  51         int error;
  52
  53         lock_system_sleep();
  54
  55         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
  56                 error = -EBUSY;
  57                 goto Unlock;
  58         }
  59
  60         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
  61                 atomic_inc(&snapshot_device_available);
  62                 error = -ENOSYS;
  63                 goto Unlock;
  64         }
  65         if(create_basic_memory_bitmaps()) {
  66                 atomic_inc(&snapshot_device_available);
  67                 error = -ENOMEM;
  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                 error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
  80                 if (error)
  81                         pm_notifier_call_chain(PM_POST_HIBERNATION);
  82         } else {
  83                 /*
  84                  * Resuming.  We may need to wait for the image device to
  85                  * appear.
  86                  */
  87                 wait_for_device_probe();
  88
  89                 data->swap = -1;
  90                 data->mode = O_WRONLY;
  91                 error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
  92                 if (error)
  93                         pm_notifier_call_chain(PM_POST_RESTORE);
  94         }
  95         if (error) {
  96                 free_basic_memory_bitmaps();
  97                 atomic_inc(&snapshot_device_available);
  98         }
  99         data->frozen = 0;
 100         data->ready = 0;
 101         data->platform_support = 0;
 102
 103  Unlock:
 104         unlock_system_sleep();
 105
 106         return error;
 107 }
 108
 109 static int snapshot_release(struct inode *inode, struct file *filp)
 110 {
 111         struct snapshot_data *data;
 112
 113         lock_system_sleep();
 114
 115         swsusp_free();
 116         free_basic_memory_bitmaps();
 117         data = filp->private_data;
 118         free_all_swap_pages(data->swap);
 119         if (data->frozen) {
 120                 pm_restore_gfp_mask();
 121                 thaw_processes();
 122         }
 123         pm_notifier_call_chain(data->mode == O_RDONLY ?
 124                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 125         atomic_inc(&snapshot_device_available);
 126
 127         unlock_system_sleep();
 128
 129         return 0;
 130 }
 131
 132 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 133                              size_t count, loff_t *offp)
 134 {
 135         struct snapshot_data *data;
 136         ssize_t res;
 137         loff_t pg_offp = *offp & ~PAGE_MASK;
 138
 139         lock_system_sleep();
 140
 141         data = filp->private_data;
 142         if (!data->ready) {
 143                 res = -ENODATA;
 144                 goto Unlock;
 145         }
 146         if (!pg_offp) { /* on page boundary? */
 147                 res = snapshot_read_next(&data->handle);
 148                 if (res <= 0)
 149                         goto Unlock;
 150         } else {
 151                 res = PAGE_SIZE - pg_offp;
 152         }
 153
 154         res = simple_read_from_buffer(buf, count, &pg_offp,
 155                         data_of(data->handle), res);
 156         if (res > 0)
 157                 *offp += res;
 158
 159  Unlock:
 160         unlock_system_sleep();
 161
 162         return res;
 163 }
 164
 165 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 166                               size_t count, loff_t *offp)
 167 {
 168         struct snapshot_data *data;
 169         ssize_t res;
 170         loff_t pg_offp = *offp & ~PAGE_MASK;
 171
 172         lock_system_sleep();
 173
 174         data = filp->private_data;
 175
 176         if (!pg_offp) {
 177                 res = snapshot_write_next(&data->handle);
 178                 if (res <= 0)
 179                         goto unlock;
 180         } else {
 181                 res = PAGE_SIZE - pg_offp;
 182         }
 183
 184         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 185                         buf, count);
 186         if (res > 0)
 187                 *offp += res;
 188 unlock:
 189         unlock_system_sleep();
 190
 191         return res;
 192 }
 193
 194 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 195                                                         unsigned long arg)
 196 {
 197         int error = 0;
 198         struct snapshot_data *data;
 199         loff_t size;
 200         sector_t offset;
 201
 202         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 203                 return -ENOTTY;
 204         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 205                 return -ENOTTY;
 206         if (!capable(CAP_SYS_ADMIN))
 207                 return -EPERM;
 208
 209         if (!mutex_trylock(&pm_mutex))
 210                 return -EBUSY;
 211
 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                         data->frozen = 1;
 227                 break;
 228
 229         case SNAPSHOT_UNFREEZE:
 230                 if (!data->frozen || data->ready)
 231                         break;
 232                 pm_restore_gfp_mask();
 233                 thaw_processes();
 234                 data->frozen = 0;
 235                 break;
 236
 237         case SNAPSHOT_CREATE_IMAGE:
 238                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 239                         error = -EPERM;
 240                         break;
 241                 }
 242                 pm_restore_gfp_mask();
 243                 error = hibernation_snapshot(data->platform_support);
 244                 if (!error) {
 245                         error = put_user(in_suspend, (int __user *)arg);
 246                         data->ready = !freezer_test_done && !error;
 247                         freezer_test_done = false;
 248                 }
 249                 break;
 250
 251         case SNAPSHOT_ATOMIC_RESTORE:
 252                 snapshot_write_finalize(&data->handle);
 253                 if (data->mode != O_WRONLY || !data->frozen ||
 254                     !snapshot_image_loaded(&data->handle)) {
 255                         error = -EPERM;
 256                         break;
 257                 }
 258                 error = hibernation_restore(data->platform_support);
 259                 break;
 260
 261         case SNAPSHOT_FREE:
 262                 swsusp_free();
 263                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 264                 data->ready = 0;
 265                 /*
 266                  * It is necessary to thaw kernel threads here, because
 267                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 268                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 269                  * thawed, the preallocation of memory carried out by
 270                  * hibernation_snapshot() might run into problems (i.e. it
 271                  * might fail or even deadlock).
 272                  */
 273                 thaw_kernel_threads();
 274                 break;
 275
 276         case SNAPSHOT_PREF_IMAGE_SIZE:
 277                 image_size = arg;
 278                 break;
 279
 280         case SNAPSHOT_GET_IMAGE_SIZE:
 281                 if (!data->ready) {
 282                         error = -ENODATA;
 283                         break;
 284                 }
 285                 size = snapshot_get_image_size();
 286                 size <<= PAGE_SHIFT;
 287                 error = put_user(size, (loff_t __user *)arg);
 288                 break;
 289
 290         case SNAPSHOT_AVAIL_SWAP_SIZE:
 291                 size = count_swap_pages(data->swap, 1);
 292                 size <<= PAGE_SHIFT;
 293                 error = put_user(size, (loff_t __user *)arg);
 294                 break;
 295
 296         case SNAPSHOT_ALLOC_SWAP_PAGE:
 297                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 298                         error = -ENODEV;
 299                         break;
 300                 }
 301                 offset = alloc_swapdev_block(data->swap);
 302                 if (offset) {
 303                         offset <<= PAGE_SHIFT;
 304                         error = put_user(offset, (loff_t __user *)arg);
 305                 } else {
 306                         error = -ENOSPC;
 307                 }
 308                 break;
 309
 310         case SNAPSHOT_FREE_SWAP_PAGES:
 311                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 312                         error = -ENODEV;
 313                         break;
 314                 }
 315                 free_all_swap_pages(data->swap);
 316                 break;
 317
 318         case SNAPSHOT_S2RAM:
 319                 if (!data->frozen) {
 320                         error = -EPERM;
 321                         break;
 322                 }
 323                 /*
 324                  * Tasks are frozen and the notifiers have been called with
 325                  * PM_HIBERNATION_PREPARE
 326                  */
 327                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 328                 data->ready = 0;
 329                 break;
 330
 331         case SNAPSHOT_PLATFORM_SUPPORT:
 332                 data->platform_support = !!arg;
 333                 break;
 334
 335         case SNAPSHOT_POWER_OFF:
 336                 if (data->platform_support)
 337                         error = hibernation_platform_enter();
 338                 break;
 339
 340         case SNAPSHOT_SET_SWAP_AREA:
 341                 if (swsusp_swap_in_use()) {
 342                         error = -EPERM;
 343                 } else {
 344                         struct resume_swap_area swap_area;
 345                         dev_t swdev;
 346
 347                         error = copy_from_user(&swap_area, (void __user *)arg,
 348                                         sizeof(struct resume_swap_area));
 349                         if (error) {
 350                                 error = -EFAULT;
 351                                 break;
 352                         }
 353
 354                         /*
 355                          * User space encodes device types as two-byte values,
 356                          * so we need to recode them
 357                          */
 358                         swdev = new_decode_dev(swap_area.dev);
 359                         if (swdev) {
 360                                 offset = swap_area.offset;
 361                                 data->swap = swap_type_of(swdev, offset, NULL);
 362                                 if (data->swap < 0)
 363                                         error = -ENODEV;
 364                         } else {
 365                                 data->swap = -1;
 366                                 error = -EINVAL;
 367                         }
 368                 }
 369                 break;
 370
 371         default:
 372                 error = -ENOTTY;
 373
 374         }
 375
 376         mutex_unlock(&pm_mutex);
 377
 378         return error;
 379 }
 380
 381 #ifdef CONFIG_COMPAT
 382
 383 struct compat_resume_swap_area {
 384         compat_loff_t offset;
 385         u32 dev;
 386 } __packed;
 387
 388 static long
 389 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 390 {
 391         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 392
 393         switch (cmd) {
 394         case SNAPSHOT_GET_IMAGE_SIZE:
 395         case SNAPSHOT_AVAIL_SWAP_SIZE:
 396         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 397                 compat_loff_t __user *uoffset = compat_ptr(arg);
 398                 loff_t offset;
 399                 mm_segment_t old_fs;
 400                 int err;
 401
 402                 old_fs = get_fs();
 403                 set_fs(KERNEL_DS);
 404                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 405                 set_fs(old_fs);
 406                 if (!err && put_user(offset, uoffset))
 407                         err = -EFAULT;
 408                 return err;
 409         }
 410
 411         case SNAPSHOT_CREATE_IMAGE:
 412                 return snapshot_ioctl(file, cmd,
 413                                       (unsigned long) compat_ptr(arg));
 414
 415         case SNAPSHOT_SET_SWAP_AREA: {
 416                 struct compat_resume_swap_area __user *u_swap_area =
 417                         compat_ptr(arg);
 418                 struct resume_swap_area swap_area;
 419                 mm_segment_t old_fs;
 420                 int err;
 421
 422                 err = get_user(swap_area.offset, &u_swap_area->offset);
 423                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 424                 if (err)
 425                         return -EFAULT;
 426                 old_fs = get_fs();
 427                 set_fs(KERNEL_DS);
 428                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 429                                      (unsigned long) &swap_area);
 430                 set_fs(old_fs);
 431                 return err;
 432         }
 433
 434         default:
 435                 return snapshot_ioctl(file, cmd, arg);
 436         }
 437 }
 438
 439 #endif /* CONFIG_COMPAT */
 440
 441 static const struct file_operations snapshot_fops = {
 442         .open = snapshot_open,
 443         .release = snapshot_release,
 444         .read = snapshot_read,
 445         .write = snapshot_write,
 446         .llseek = no_llseek,
 447         .unlocked_ioctl = snapshot_ioctl,
 448 #ifdef CONFIG_COMPAT
 449         .compat_ioctl = snapshot_compat_ioctl,
 450 #endif
 451 };
 452
 453 static struct miscdevice snapshot_device = {
 454         .minor = SNAPSHOT_MINOR,
 455         .name = "snapshot",
 456         .fops = &snapshot_fops,
 457 };
 458
 459 static int __init snapshot_device_init(void)
 460 {
 461         return misc_register(&snapshot_device);
 462 };
 463
 464 device_initcall(snapshot_device_init);