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/kmod.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 #include <scsi/scsi_scan.h>
  29
  30 #include <asm/uaccess.h>
  31
  32 #include "power.h"
  33
  34
  35 #define SNAPSHOT_MINOR  231
  36
  37 static struct snapshot_data {
  38         struct snapshot_handle handle;
  39         int swap;
  40         int mode;
  41         char frozen;
  42         char ready;
  43         char platform_support;
  44 } snapshot_state;
  45
  46 atomic_t snapshot_device_available = ATOMIC_INIT(1);
  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                 scsi_complete_async_scans();
  89
  90                 data->swap = -1;
  91                 data->mode = O_WRONLY;
  92                 error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
  93                 if (error)
  94                         pm_notifier_call_chain(PM_POST_RESTORE);
  95         }
  96         if (error) {
  97                 free_basic_memory_bitmaps();
  98                 atomic_inc(&snapshot_device_available);
  99         }
 100         data->frozen = 0;
 101         data->ready = 0;
 102         data->platform_support = 0;
 103
 104  Unlock:
 105         unlock_system_sleep();
 106
 107         return error;
 108 }
 109
 110 static int snapshot_release(struct inode *inode, struct file *filp)
 111 {
 112         struct snapshot_data *data;
 113
 114         lock_system_sleep();
 115
 116         swsusp_free();
 117         free_basic_memory_bitmaps();
 118         data = filp->private_data;
 119         free_all_swap_pages(data->swap);
 120         if (data->frozen) {
 121                 pm_restore_gfp_mask();
 122                 thaw_processes();
 123         }
 124         pm_notifier_call_chain(data->mode == O_RDONLY ?
 125                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 126         atomic_inc(&snapshot_device_available);
 127
 128         unlock_system_sleep();
 129
 130         return 0;
 131 }
 132
 133 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 134                              size_t count, loff_t *offp)
 135 {
 136         struct snapshot_data *data;
 137         ssize_t res;
 138         loff_t pg_offp = *offp & ~PAGE_MASK;
 139
 140         lock_system_sleep();
 141
 142         data = filp->private_data;
 143         if (!data->ready) {
 144                 res = -ENODATA;
 145                 goto Unlock;
 146         }
 147         if (!pg_offp) { /* on page boundary? */
 148                 res = snapshot_read_next(&data->handle);
 149                 if (res <= 0)
 150                         goto Unlock;
 151         } else {
 152                 res = PAGE_SIZE - pg_offp;
 153         }
 154
 155         res = simple_read_from_buffer(buf, count, &pg_offp,
 156                         data_of(data->handle), res);
 157         if (res > 0)
 158                 *offp += res;
 159
 160  Unlock:
 161         unlock_system_sleep();
 162
 163         return res;
 164 }
 165
 166 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 167                               size_t count, loff_t *offp)
 168 {
 169         struct snapshot_data *data;
 170         ssize_t res;
 171         loff_t pg_offp = *offp & ~PAGE_MASK;
 172
 173         lock_system_sleep();
 174
 175         data = filp->private_data;
 176
 177         if (!pg_offp) {
 178                 res = snapshot_write_next(&data->handle);
 179                 if (res <= 0)
 180                         goto unlock;
 181         } else {
 182                 res = PAGE_SIZE - pg_offp;
 183         }
 184
 185         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 186                         buf, count);
 187         if (res > 0)
 188                 *offp += res;
 189 unlock:
 190         unlock_system_sleep();
 191
 192         return res;
 193 }
 194
 195 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 196                                                         unsigned long arg)
 197 {
 198         int error = 0;
 199         struct snapshot_data *data;
 200         loff_t size;
 201         sector_t offset;
 202
 203         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 204                 return -ENOTTY;
 205         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 206                 return -ENOTTY;
 207         if (!capable(CAP_SYS_ADMIN))
 208                 return -EPERM;
 209
 210         if (!mutex_trylock(&pm_mutex))
 211                 return -EBUSY;
 212
 213         data = filp->private_data;
 214
 215         switch (cmd) {
 216
 217         case SNAPSHOT_FREEZE:
 218                 if (data->frozen)
 219                         break;
 220
 221                 printk("Syncing filesystems ... ");
 222                 sys_sync();
 223                 printk("done.\n");
 224
 225                 error = usermodehelper_disable();
 226                 if (error)
 227                         break;
 228
 229                 error = freeze_processes();
 230                 if (error)
 231                         usermodehelper_enable();
 232                 else
 233                         data->frozen = 1;
 234                 break;
 235
 236         case SNAPSHOT_UNFREEZE:
 237                 if (!data->frozen || data->ready)
 238                         break;
 239                 pm_restore_gfp_mask();
 240                 thaw_processes();
 241                 usermodehelper_enable();
 242                 data->frozen = 0;
 243                 break;
 244
 245         case SNAPSHOT_CREATE_IMAGE:
 246                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 247                         error = -EPERM;
 248                         break;
 249                 }
 250                 pm_restore_gfp_mask();
 251                 error = hibernation_snapshot(data->platform_support);
 252                 if (!error) {
 253                         error = put_user(in_suspend, (int __user *)arg);
 254                         data->ready = !freezer_test_done && !error;
 255                         freezer_test_done = false;
 256                 }
 257                 break;
 258
 259         case SNAPSHOT_ATOMIC_RESTORE:
 260                 snapshot_write_finalize(&data->handle);
 261                 if (data->mode != O_WRONLY || !data->frozen ||
 262                     !snapshot_image_loaded(&data->handle)) {
 263                         error = -EPERM;
 264                         break;
 265                 }
 266                 error = hibernation_restore(data->platform_support);
 267                 break;
 268
 269         case SNAPSHOT_FREE:
 270                 swsusp_free();
 271                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 272                 data->ready = 0;
 273                 /*
 274                  * It is necessary to thaw kernel threads here, because
 275                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 276                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 277                  * thawed, the preallocation of memory carried out by
 278                  * hibernation_snapshot() might run into problems (i.e. it
 279                  * might fail or even deadlock).
 280                  */
 281                 thaw_kernel_threads();
 282                 break;
 283
 284         case SNAPSHOT_PREF_IMAGE_SIZE:
 285                 image_size = arg;
 286                 break;
 287
 288         case SNAPSHOT_GET_IMAGE_SIZE:
 289                 if (!data->ready) {
 290                         error = -ENODATA;
 291                         break;
 292                 }
 293                 size = snapshot_get_image_size();
 294                 size <<= PAGE_SHIFT;
 295                 error = put_user(size, (loff_t __user *)arg);
 296                 break;
 297
 298         case SNAPSHOT_AVAIL_SWAP_SIZE:
 299                 size = count_swap_pages(data->swap, 1);
 300                 size <<= PAGE_SHIFT;
 301                 error = put_user(size, (loff_t __user *)arg);
 302                 break;
 303
 304         case SNAPSHOT_ALLOC_SWAP_PAGE:
 305                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 306                         error = -ENODEV;
 307                         break;
 308                 }
 309                 offset = alloc_swapdev_block(data->swap);
 310                 if (offset) {
 311                         offset <<= PAGE_SHIFT;
 312                         error = put_user(offset, (loff_t __user *)arg);
 313                 } else {
 314                         error = -ENOSPC;
 315                 }
 316                 break;
 317
 318         case SNAPSHOT_FREE_SWAP_PAGES:
 319                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 320                         error = -ENODEV;
 321                         break;
 322                 }
 323                 free_all_swap_pages(data->swap);
 324                 break;
 325
 326         case SNAPSHOT_S2RAM:
 327                 if (!data->frozen) {
 328                         error = -EPERM;
 329                         break;
 330                 }
 331                 /*
 332                  * Tasks are frozen and the notifiers have been called with
 333                  * PM_HIBERNATION_PREPARE
 334                  */
 335                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 336                 data->ready = 0;
 337                 break;
 338
 339         case SNAPSHOT_PLATFORM_SUPPORT:
 340                 data->platform_support = !!arg;
 341                 break;
 342
 343         case SNAPSHOT_POWER_OFF:
 344                 if (data->platform_support)
 345                         error = hibernation_platform_enter();
 346                 break;
 347
 348         case SNAPSHOT_SET_SWAP_AREA:
 349                 if (swsusp_swap_in_use()) {
 350                         error = -EPERM;
 351                 } else {
 352                         struct resume_swap_area swap_area;
 353                         dev_t swdev;
 354
 355                         error = copy_from_user(&swap_area, (void __user *)arg,
 356                                         sizeof(struct resume_swap_area));
 357                         if (error) {
 358                                 error = -EFAULT;
 359                                 break;
 360                         }
 361
 362                         /*
 363                          * User space encodes device types as two-byte values,
 364                          * so we need to recode them
 365                          */
 366                         swdev = new_decode_dev(swap_area.dev);
 367                         if (swdev) {
 368                                 offset = swap_area.offset;
 369                                 data->swap = swap_type_of(swdev, offset, NULL);
 370                                 if (data->swap < 0)
 371                                         error = -ENODEV;
 372                         } else {
 373                                 data->swap = -1;
 374                                 error = -EINVAL;
 375                         }
 376                 }
 377                 break;
 378
 379         default:
 380                 error = -ENOTTY;
 381
 382         }
 383
 384         mutex_unlock(&pm_mutex);
 385
 386         return error;
 387 }
 388
 389 #ifdef CONFIG_COMPAT
 390
 391 struct compat_resume_swap_area {
 392         compat_loff_t offset;
 393         u32 dev;
 394 } __packed;
 395
 396 static long
 397 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 398 {
 399         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 400
 401         switch (cmd) {
 402         case SNAPSHOT_GET_IMAGE_SIZE:
 403         case SNAPSHOT_AVAIL_SWAP_SIZE:
 404         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 405                 compat_loff_t __user *uoffset = compat_ptr(arg);
 406                 loff_t offset;
 407                 mm_segment_t old_fs;
 408                 int err;
 409
 410                 old_fs = get_fs();
 411                 set_fs(KERNEL_DS);
 412                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 413                 set_fs(old_fs);
 414                 if (!err && put_user(offset, uoffset))
 415                         err = -EFAULT;
 416                 return err;
 417         }
 418
 419         case SNAPSHOT_CREATE_IMAGE:
 420                 return snapshot_ioctl(file, cmd,
 421                                       (unsigned long) compat_ptr(arg));
 422
 423         case SNAPSHOT_SET_SWAP_AREA: {
 424                 struct compat_resume_swap_area __user *u_swap_area =
 425                         compat_ptr(arg);
 426                 struct resume_swap_area swap_area;
 427                 mm_segment_t old_fs;
 428                 int err;
 429
 430                 err = get_user(swap_area.offset, &u_swap_area->offset);
 431                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 432                 if (err)
 433                         return -EFAULT;
 434                 old_fs = get_fs();
 435                 set_fs(KERNEL_DS);
 436                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 437                                      (unsigned long) &swap_area);
 438                 set_fs(old_fs);
 439                 return err;
 440         }
 441
 442         default:
 443                 return snapshot_ioctl(file, cmd, arg);
 444         }
 445 }
 446
 447 #endif /* CONFIG_COMPAT */
 448
 449 static const struct file_operations snapshot_fops = {
 450         .open = snapshot_open,
 451         .release = snapshot_release,
 452         .read = snapshot_read,
 453         .write = snapshot_write,
 454         .llseek = no_llseek,
 455         .unlocked_ioctl = snapshot_ioctl,
 456 #ifdef CONFIG_COMPAT
 457         .compat_ioctl = snapshot_compat_ioctl,
 458 #endif
 459 };
 460
 461 static struct miscdevice snapshot_device = {
 462         .minor = SNAPSHOT_MINOR,
 463         .name = "snapshot",
 464         .fops = &snapshot_fops,
 465 };
 466
 467 static int __init snapshot_device_init(void)
 468 {
 469         return misc_register(&snapshot_device);
 470 };
 471
 472 device_initcall(snapshot_device_init);