kernel/power/user.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/kernel/power/user.c
   4  *
   5  * This file provides the user space interface for software suspend/resume.
   6  *
   7  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
   8  */
   9
  10 #include <linux/suspend.h>
  11 #include <linux/reboot.h>
  12 #include <linux/string.h>
  13 #include <linux/device.h>
  14 #include <linux/miscdevice.h>
  15 #include <linux/mm.h>
  16 #include <linux/swap.h>
  17 #include <linux/swapops.h>
  18 #include <linux/pm.h>
  19 #include <linux/fs.h>
  20 #include <linux/compat.h>
  21 #include <linux/console.h>
  22 #include <linux/cpu.h>
  23 #include <linux/freezer.h>
  24
  25 #include <linux/uaccess.h>
  26
  27 #include "power.h"
  28
  29 static bool need_wait;
  30
  31 #define SNAPSHOT_MINOR  231
  32
  33 static struct snapshot_data {
  34         struct snapshot_handle handle;
  35         int swap;
  36         int mode;
  37         bool frozen;
  38         bool ready;
  39         bool platform_support;
  40         bool free_bitmaps;
  41 } snapshot_state;
  42
  43 atomic_t snapshot_device_available = ATOMIC_INIT(1);
  44
  45 static int snapshot_open(struct inode *inode, struct file *filp)
  46 {
  47         struct snapshot_data *data;
  48         int error, nr_calls = 0;
  49
  50         if (!hibernation_available())
  51                 return -EPERM;
  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         nonseekable_open(inode, filp);
  66         data = &snapshot_state;
  67         filp->private_data = data;
  68         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  69         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  70                 /* Hibernating.  The image device should be accessible. */
  71                 data->swap = swsusp_resume_device ?
  72                         swap_type_of(swsusp_resume_device, 0, NULL) : -1;
  73                 data->mode = O_RDONLY;
  74                 data->free_bitmaps = false;
  75                 error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
  76                 if (error)
  77                         __pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
  78         } else {
  79                 /*
  80                  * Resuming.  We may need to wait for the image device to
  81                  * appear.
  82                  */
  83                 need_wait = true;
  84
  85                 data->swap = -1;
  86                 data->mode = O_WRONLY;
  87                 error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
  88                 if (!error) {
  89                         error = create_basic_memory_bitmaps();
  90                         data->free_bitmaps = !error;
  91                 } else
  92                         nr_calls--;
  93
  94                 if (error)
  95                         __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
  96         }
  97         if (error)
  98                 atomic_inc(&snapshot_device_available);
  99
 100         data->frozen = false;
 101         data->ready = false;
 102         data->platform_support = false;
 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         data = filp->private_data;
 118         free_all_swap_pages(data->swap);
 119         if (data->frozen) {
 120                 pm_restore_gfp_mask();
 121                 free_basic_memory_bitmaps();
 122                 thaw_processes();
 123         } else if (data->free_bitmaps) {
 124                 free_basic_memory_bitmaps();
 125         }
 126         pm_notifier_call_chain(data->mode == O_RDONLY ?
 127                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 128         atomic_inc(&snapshot_device_available);
 129
 130         unlock_system_sleep();
 131
 132         return 0;
 133 }
 134
 135 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 136                              size_t count, loff_t *offp)
 137 {
 138         struct snapshot_data *data;
 139         ssize_t res;
 140         loff_t pg_offp = *offp & ~PAGE_MASK;
 141
 142         lock_system_sleep();
 143
 144         data = filp->private_data;
 145         if (!data->ready) {
 146                 res = -ENODATA;
 147                 goto Unlock;
 148         }
 149         if (!pg_offp) { /* on page boundary? */
 150                 res = snapshot_read_next(&data->handle);
 151                 if (res <= 0)
 152                         goto Unlock;
 153         } else {
 154                 res = PAGE_SIZE - pg_offp;
 155         }
 156
 157         res = simple_read_from_buffer(buf, count, &pg_offp,
 158                         data_of(data->handle), res);
 159         if (res > 0)
 160                 *offp += res;
 161
 162  Unlock:
 163         unlock_system_sleep();
 164
 165         return res;
 166 }
 167
 168 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 169                               size_t count, loff_t *offp)
 170 {
 171         struct snapshot_data *data;
 172         ssize_t res;
 173         loff_t pg_offp = *offp & ~PAGE_MASK;
 174
 175         if (need_wait) {
 176                 wait_for_device_probe();
 177                 need_wait = false;
 178         }
 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         if (!data_of(data->handle)) {
 193                 res = -EINVAL;
 194                 goto unlock;
 195         }
 196
 197         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 198                         buf, count);
 199         if (res > 0)
 200                 *offp += res;
 201 unlock:
 202         unlock_system_sleep();
 203
 204         return res;
 205 }
 206
 207 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 208                                                         unsigned long arg)
 209 {
 210         int error = 0;
 211         struct snapshot_data *data;
 212         loff_t size;
 213         sector_t offset;
 214
 215         if (need_wait) {
 216                 wait_for_device_probe();
 217                 need_wait = false;
 218         }
 219
 220         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 221                 return -ENOTTY;
 222         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 223                 return -ENOTTY;
 224         if (!capable(CAP_SYS_ADMIN))
 225                 return -EPERM;
 226
 227         if (!mutex_trylock(&system_transition_mutex))
 228                 return -EBUSY;
 229
 230         lock_device_hotplug();
 231         data = filp->private_data;
 232
 233         switch (cmd) {
 234
 235         case SNAPSHOT_FREEZE:
 236                 if (data->frozen)
 237                         break;
 238
 239                 ksys_sync_helper();
 240
 241                 error = freeze_processes();
 242                 if (error)
 243                         break;
 244
 245                 error = create_basic_memory_bitmaps();
 246                 if (error)
 247                         thaw_processes();
 248                 else
 249                         data->frozen = true;
 250
 251                 break;
 252
 253         case SNAPSHOT_UNFREEZE:
 254                 if (!data->frozen || data->ready)
 255                         break;
 256                 pm_restore_gfp_mask();
 257                 free_basic_memory_bitmaps();
 258                 data->free_bitmaps = false;
 259                 thaw_processes();
 260                 data->frozen = false;
 261                 break;
 262
 263         case SNAPSHOT_CREATE_IMAGE:
 264                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 265                         error = -EPERM;
 266                         break;
 267                 }
 268                 pm_restore_gfp_mask();
 269                 error = hibernation_snapshot(data->platform_support);
 270                 if (!error) {
 271                         error = put_user(in_suspend, (int __user *)arg);
 272                         data->ready = !freezer_test_done && !error;
 273                         freezer_test_done = false;
 274                 }
 275                 break;
 276
 277         case SNAPSHOT_ATOMIC_RESTORE:
 278                 snapshot_write_finalize(&data->handle);
 279                 if (data->mode != O_WRONLY || !data->frozen ||
 280                     !snapshot_image_loaded(&data->handle)) {
 281                         error = -EPERM;
 282                         break;
 283                 }
 284                 error = hibernation_restore(data->platform_support);
 285                 break;
 286
 287         case SNAPSHOT_FREE:
 288                 swsusp_free();
 289                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 290                 data->ready = false;
 291                 /*
 292                  * It is necessary to thaw kernel threads here, because
 293                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 294                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 295                  * thawed, the preallocation of memory carried out by
 296                  * hibernation_snapshot() might run into problems (i.e. it
 297                  * might fail or even deadlock).
 298                  */
 299                 thaw_kernel_threads();
 300                 break;
 301
 302         case SNAPSHOT_PREF_IMAGE_SIZE:
 303                 image_size = arg;
 304                 break;
 305
 306         case SNAPSHOT_GET_IMAGE_SIZE:
 307                 if (!data->ready) {
 308                         error = -ENODATA;
 309                         break;
 310                 }
 311                 size = snapshot_get_image_size();
 312                 size <<= PAGE_SHIFT;
 313                 error = put_user(size, (loff_t __user *)arg);
 314                 break;
 315
 316         case SNAPSHOT_AVAIL_SWAP_SIZE:
 317                 size = count_swap_pages(data->swap, 1);
 318                 size <<= PAGE_SHIFT;
 319                 error = put_user(size, (loff_t __user *)arg);
 320                 break;
 321
 322         case SNAPSHOT_ALLOC_SWAP_PAGE:
 323                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 324                         error = -ENODEV;
 325                         break;
 326                 }
 327                 offset = alloc_swapdev_block(data->swap);
 328                 if (offset) {
 329                         offset <<= PAGE_SHIFT;
 330                         error = put_user(offset, (loff_t __user *)arg);
 331                 } else {
 332                         error = -ENOSPC;
 333                 }
 334                 break;
 335
 336         case SNAPSHOT_FREE_SWAP_PAGES:
 337                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 338                         error = -ENODEV;
 339                         break;
 340                 }
 341                 free_all_swap_pages(data->swap);
 342                 break;
 343
 344         case SNAPSHOT_S2RAM:
 345                 if (!data->frozen) {
 346                         error = -EPERM;
 347                         break;
 348                 }
 349                 /*
 350                  * Tasks are frozen and the notifiers have been called with
 351                  * PM_HIBERNATION_PREPARE
 352                  */
 353                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 354                 data->ready = false;
 355                 break;
 356
 357         case SNAPSHOT_PLATFORM_SUPPORT:
 358                 data->platform_support = !!arg;
 359                 break;
 360
 361         case SNAPSHOT_POWER_OFF:
 362                 if (data->platform_support)
 363                         error = hibernation_platform_enter();
 364                 break;
 365
 366         case SNAPSHOT_SET_SWAP_AREA:
 367                 if (swsusp_swap_in_use()) {
 368                         error = -EPERM;
 369                 } else {
 370                         struct resume_swap_area swap_area;
 371                         dev_t swdev;
 372
 373                         error = copy_from_user(&swap_area, (void __user *)arg,
 374                                         sizeof(struct resume_swap_area));
 375                         if (error) {
 376                                 error = -EFAULT;
 377                                 break;
 378                         }
 379
 380                         /*
 381                          * User space encodes device types as two-byte values,
 382                          * so we need to recode them
 383                          */
 384                         swdev = new_decode_dev(swap_area.dev);
 385                         if (swdev) {
 386                                 offset = swap_area.offset;
 387                                 data->swap = swap_type_of(swdev, offset, NULL);
 388                                 if (data->swap < 0)
 389                                         error = -ENODEV;
 390                         } else {
 391                                 data->swap = -1;
 392                                 error = -EINVAL;
 393                         }
 394                 }
 395                 break;
 396
 397         default:
 398                 error = -ENOTTY;
 399
 400         }
 401
 402         unlock_device_hotplug();
 403         mutex_unlock(&system_transition_mutex);
 404
 405         return error;
 406 }
 407
 408 #ifdef CONFIG_COMPAT
 409
 410 struct compat_resume_swap_area {
 411         compat_loff_t offset;
 412         u32 dev;
 413 } __packed;
 414
 415 static long
 416 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 417 {
 418         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 419
 420         switch (cmd) {
 421         case SNAPSHOT_GET_IMAGE_SIZE:
 422         case SNAPSHOT_AVAIL_SWAP_SIZE:
 423         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 424                 compat_loff_t __user *uoffset = compat_ptr(arg);
 425                 loff_t offset;
 426                 mm_segment_t old_fs;
 427                 int err;
 428
 429                 old_fs = get_fs();
 430                 set_fs(KERNEL_DS);
 431                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 432                 set_fs(old_fs);
 433                 if (!err && put_user(offset, uoffset))
 434                         err = -EFAULT;
 435                 return err;
 436         }
 437
 438         case SNAPSHOT_CREATE_IMAGE:
 439                 return snapshot_ioctl(file, cmd,
 440                                       (unsigned long) compat_ptr(arg));
 441
 442         case SNAPSHOT_SET_SWAP_AREA: {
 443                 struct compat_resume_swap_area __user *u_swap_area =
 444                         compat_ptr(arg);
 445                 struct resume_swap_area swap_area;
 446                 mm_segment_t old_fs;
 447                 int err;
 448
 449                 err = get_user(swap_area.offset, &u_swap_area->offset);
 450                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 451                 if (err)
 452                         return -EFAULT;
 453                 old_fs = get_fs();
 454                 set_fs(KERNEL_DS);
 455                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 456                                      (unsigned long) &swap_area);
 457                 set_fs(old_fs);
 458                 return err;
 459         }
 460
 461         default:
 462                 return snapshot_ioctl(file, cmd, arg);
 463         }
 464 }
 465
 466 #endif /* CONFIG_COMPAT */
 467
 468 static const struct file_operations snapshot_fops = {
 469         .open = snapshot_open,
 470         .release = snapshot_release,
 471         .read = snapshot_read,
 472         .write = snapshot_write,
 473         .llseek = no_llseek,
 474         .unlocked_ioctl = snapshot_ioctl,
 475 #ifdef CONFIG_COMPAT
 476         .compat_ioctl = snapshot_compat_ioctl,
 477 #endif
 478 };
 479
 480 static struct miscdevice snapshot_device = {
 481         .minor = SNAPSHOT_MINOR,
 482         .name = "snapshot",
 483         .fops = &snapshot_fops,
 484 };
 485
 486 static int __init snapshot_device_init(void)
 487 {
 488         return misc_register(&snapshot_device);
 489 };
 490
 491 device_initcall(snapshot_device_init);