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                 data->free_bitmaps = false;
  74                 error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
  75                 if (error)
  76                         pm_notifier_call_chain(PM_POST_HIBERNATION);
  77         } else {
  78                 /*
  79                  * Resuming.  We may need to wait for the image device to
  80                  * appear.
  81                  */
  82                 wait_for_device_probe();
  83
  84                 data->swap = -1;
  85                 data->mode = O_WRONLY;
  86                 error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
  87                 if (!error) {
  88                         error = create_basic_memory_bitmaps();
  89                         data->free_bitmaps = !error;
  90                 }
  91                 if (error)
  92                         pm_notifier_call_chain(PM_POST_RESTORE);
  93         }
  94         if (error)
  95                 atomic_inc(&snapshot_device_available);
  96
  97         data->frozen = false;
  98         data->ready = false;
  99         data->platform_support = false;
 100
 101  Unlock:
 102         unlock_system_sleep();
 103
 104         return error;
 105 }
 106
 107 static int snapshot_release(struct inode *inode, struct file *filp)
 108 {
 109         struct snapshot_data *data;
 110
 111         lock_system_sleep();
 112
 113         swsusp_free();
 114         data = filp->private_data;
 115         free_all_swap_pages(data->swap);
 116         if (data->frozen) {
 117                 pm_restore_gfp_mask();
 118                 free_basic_memory_bitmaps();
 119                 thaw_processes();
 120         } else if (data->free_bitmaps) {
 121                 free_basic_memory_bitmaps();
 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         lock_device_hotplug();
 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 = freeze_processes();
 226                 if (error)
 227                         break;
 228
 229                 error = create_basic_memory_bitmaps();
 230                 if (error)
 231                         thaw_processes();
 232                 else
 233                         data->frozen = true;
 234
 235                 break;
 236
 237         case SNAPSHOT_UNFREEZE:
 238                 if (!data->frozen || data->ready)
 239                         break;
 240                 pm_restore_gfp_mask();
 241                 free_basic_memory_bitmaps();
 242                 data->free_bitmaps = false;
 243                 thaw_processes();
 244                 data->frozen = false;
 245                 break;
 246
 247         case SNAPSHOT_CREATE_IMAGE:
 248                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 249                         error = -EPERM;
 250                         break;
 251                 }
 252                 pm_restore_gfp_mask();
 253                 error = hibernation_snapshot(data->platform_support);
 254                 if (!error) {
 255                         error = put_user(in_suspend, (int __user *)arg);
 256                         data->ready = !freezer_test_done && !error;
 257                         freezer_test_done = false;
 258                 }
 259                 break;
 260
 261         case SNAPSHOT_ATOMIC_RESTORE:
 262                 snapshot_write_finalize(&data->handle);
 263                 if (data->mode != O_WRONLY || !data->frozen ||
 264                     !snapshot_image_loaded(&data->handle)) {
 265                         error = -EPERM;
 266                         break;
 267                 }
 268                 error = hibernation_restore(data->platform_support);
 269                 break;
 270
 271         case SNAPSHOT_FREE:
 272                 swsusp_free();
 273                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 274                 data->ready = false;
 275                 /*
 276                  * It is necessary to thaw kernel threads here, because
 277                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 278                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 279                  * thawed, the preallocation of memory carried out by
 280                  * hibernation_snapshot() might run into problems (i.e. it
 281                  * might fail or even deadlock).
 282                  */
 283                 thaw_kernel_threads();
 284                 break;
 285
 286         case SNAPSHOT_PREF_IMAGE_SIZE:
 287                 image_size = arg;
 288                 break;
 289
 290         case SNAPSHOT_GET_IMAGE_SIZE:
 291                 if (!data->ready) {
 292                         error = -ENODATA;
 293                         break;
 294                 }
 295                 size = snapshot_get_image_size();
 296                 size <<= PAGE_SHIFT;
 297                 error = put_user(size, (loff_t __user *)arg);
 298                 break;
 299
 300         case SNAPSHOT_AVAIL_SWAP_SIZE:
 301                 size = count_swap_pages(data->swap, 1);
 302                 size <<= PAGE_SHIFT;
 303                 error = put_user(size, (loff_t __user *)arg);
 304                 break;
 305
 306         case SNAPSHOT_ALLOC_SWAP_PAGE:
 307                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 308                         error = -ENODEV;
 309                         break;
 310                 }
 311                 offset = alloc_swapdev_block(data->swap);
 312                 if (offset) {
 313                         offset <<= PAGE_SHIFT;
 314                         error = put_user(offset, (loff_t __user *)arg);
 315                 } else {
 316                         error = -ENOSPC;
 317                 }
 318                 break;
 319
 320         case SNAPSHOT_FREE_SWAP_PAGES:
 321                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 322                         error = -ENODEV;
 323                         break;
 324                 }
 325                 free_all_swap_pages(data->swap);
 326                 break;
 327
 328         case SNAPSHOT_S2RAM:
 329                 if (!data->frozen) {
 330                         error = -EPERM;
 331                         break;
 332                 }
 333                 /*
 334                  * Tasks are frozen and the notifiers have been called with
 335                  * PM_HIBERNATION_PREPARE
 336                  */
 337                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 338                 data->ready = false;
 339                 break;
 340
 341         case SNAPSHOT_PLATFORM_SUPPORT:
 342                 data->platform_support = !!arg;
 343                 break;
 344
 345         case SNAPSHOT_POWER_OFF:
 346                 if (data->platform_support)
 347                         error = hibernation_platform_enter();
 348                 break;
 349
 350         case SNAPSHOT_SET_SWAP_AREA:
 351                 if (swsusp_swap_in_use()) {
 352                         error = -EPERM;
 353                 } else {
 354                         struct resume_swap_area swap_area;
 355                         dev_t swdev;
 356
 357                         error = copy_from_user(&swap_area, (void __user *)arg,
 358                                         sizeof(struct resume_swap_area));
 359                         if (error) {
 360                                 error = -EFAULT;
 361                                 break;
 362                         }
 363
 364                         /*
 365                          * User space encodes device types as two-byte values,
 366                          * so we need to recode them
 367                          */
 368                         swdev = new_decode_dev(swap_area.dev);
 369                         if (swdev) {
 370                                 offset = swap_area.offset;
 371                                 data->swap = swap_type_of(swdev, offset, NULL);
 372                                 if (data->swap < 0)
 373                                         error = -ENODEV;
 374                         } else {
 375                                 data->swap = -1;
 376                                 error = -EINVAL;
 377                         }
 378                 }
 379                 break;
 380
 381         default:
 382                 error = -ENOTTY;
 383
 384         }
 385
 386         unlock_device_hotplug();
 387         mutex_unlock(&pm_mutex);
 388
 389         return error;
 390 }
 391
 392 #ifdef CONFIG_COMPAT
 393
 394 struct compat_resume_swap_area {
 395         compat_loff_t offset;
 396         u32 dev;
 397 } __packed;
 398
 399 static long
 400 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 401 {
 402         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 403
 404         switch (cmd) {
 405         case SNAPSHOT_GET_IMAGE_SIZE:
 406         case SNAPSHOT_AVAIL_SWAP_SIZE:
 407         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 408                 compat_loff_t __user *uoffset = compat_ptr(arg);
 409                 loff_t offset;
 410                 mm_segment_t old_fs;
 411                 int err;
 412
 413                 old_fs = get_fs();
 414                 set_fs(KERNEL_DS);
 415                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 416                 set_fs(old_fs);
 417                 if (!err && put_user(offset, uoffset))
 418                         err = -EFAULT;
 419                 return err;
 420         }
 421
 422         case SNAPSHOT_CREATE_IMAGE:
 423                 return snapshot_ioctl(file, cmd,
 424                                       (unsigned long) compat_ptr(arg));
 425
 426         case SNAPSHOT_SET_SWAP_AREA: {
 427                 struct compat_resume_swap_area __user *u_swap_area =
 428                         compat_ptr(arg);
 429                 struct resume_swap_area swap_area;
 430                 mm_segment_t old_fs;
 431                 int err;
 432
 433                 err = get_user(swap_area.offset, &u_swap_area->offset);
 434                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 435                 if (err)
 436                         return -EFAULT;
 437                 old_fs = get_fs();
 438                 set_fs(KERNEL_DS);
 439                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 440                                      (unsigned long) &swap_area);
 441                 set_fs(old_fs);
 442                 return err;
 443         }
 444
 445         default:
 446                 return snapshot_ioctl(file, cmd, arg);
 447         }
 448 }
 449
 450 #endif /* CONFIG_COMPAT */
 451
 452 static const struct file_operations snapshot_fops = {
 453         .open = snapshot_open,
 454         .release = snapshot_release,
 455         .read = snapshot_read,
 456         .write = snapshot_write,
 457         .llseek = no_llseek,
 458         .unlocked_ioctl = snapshot_ioctl,
 459 #ifdef CONFIG_COMPAT
 460         .compat_ioctl = snapshot_compat_ioctl,
 461 #endif
 462 };
 463
 464 static struct miscdevice snapshot_device = {
 465         .minor = SNAPSHOT_MINOR,
 466         .name = "snapshot",
 467         .fops = &snapshot_fops,
 468 };
 469
 470 static int __init snapshot_device_init(void)
 471 {
 472         return misc_register(&snapshot_device);
 473 };
 474
 475 device_initcall(snapshot_device_init);