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 static struct snapshot_data {
  32         struct snapshot_handle handle;
  33         int swap;
  34         int mode;
  35         bool frozen;
  36         bool ready;
  37         bool platform_support;
  38         bool free_bitmaps;
  39         dev_t dev;
  40 } snapshot_state;
  41
  42 int is_hibernate_resume_dev(dev_t dev)
  43 {
  44         return hibernation_available() && snapshot_state.dev == dev;
  45 }
  46
  47 static int snapshot_open(struct inode *inode, struct file *filp)
  48 {
  49         struct snapshot_data *data;
  50         unsigned int sleep_flags;
  51         int error;
  52
  53         if (!hibernation_available())
  54                 return -EPERM;
  55
  56         sleep_flags = lock_system_sleep();
  57
  58         if (!hibernate_acquire()) {
  59                 error = -EBUSY;
  60                 goto Unlock;
  61         }
  62
  63         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
  64                 hibernate_release();
  65                 error = -ENOSYS;
  66                 goto Unlock;
  67         }
  68         nonseekable_open(inode, filp);
  69         data = &snapshot_state;
  70         filp->private_data = data;
  71         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  72         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  73                 /* Hibernating.  The image device should be accessible. */
  74                 data->swap = swap_type_of(swsusp_resume_device, 0);
  75                 data->mode = O_RDONLY;
  76                 data->free_bitmaps = false;
  77                 error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
  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_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE);
  88                 if (!error) {
  89                         error = create_basic_memory_bitmaps();
  90                         data->free_bitmaps = !error;
  91                 }
  92         }
  93         if (error)
  94                 hibernate_release();
  95
  96         data->frozen = false;
  97         data->ready = false;
  98         data->platform_support = false;
  99         data->dev = 0;
 100
 101  Unlock:
 102         unlock_system_sleep(sleep_flags);
 103
 104         return error;
 105 }
 106
 107 static int snapshot_release(struct inode *inode, struct file *filp)
 108 {
 109         struct snapshot_data *data;
 110         unsigned int sleep_flags;
 111
 112         sleep_flags = lock_system_sleep();
 113
 114         swsusp_free();
 115         data = filp->private_data;
 116         data->dev = 0;
 117         free_all_swap_pages(data->swap);
 118         if (data->frozen) {
 119                 pm_restore_gfp_mask();
 120                 free_basic_memory_bitmaps();
 121                 thaw_processes();
 122         } else if (data->free_bitmaps) {
 123                 free_basic_memory_bitmaps();
 124         }
 125         pm_notifier_call_chain(data->mode == O_RDONLY ?
 126                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 127         hibernate_release();
 128
 129         unlock_system_sleep(sleep_flags);
 130
 131         return 0;
 132 }
 133
 134 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 135                              size_t count, loff_t *offp)
 136 {
 137         loff_t pg_offp = *offp & ~PAGE_MASK;
 138         struct snapshot_data *data;
 139         unsigned int sleep_flags;
 140         ssize_t res;
 141
 142         sleep_flags = 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(sleep_flags);
 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         loff_t pg_offp = *offp & ~PAGE_MASK;
 172         struct snapshot_data *data;
 173         unsigned long sleep_flags;
 174         ssize_t res;
 175
 176         if (need_wait) {
 177                 wait_for_device_probe();
 178                 need_wait = false;
 179         }
 180
 181         sleep_flags = lock_system_sleep();
 182
 183         data = filp->private_data;
 184
 185         if (!pg_offp) {
 186                 res = snapshot_write_next(&data->handle);
 187                 if (res <= 0)
 188                         goto unlock;
 189         } else {
 190                 res = PAGE_SIZE;
 191         }
 192
 193         if (!data_of(data->handle)) {
 194                 res = -EINVAL;
 195                 goto unlock;
 196         }
 197
 198         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 199                         buf, count);
 200         if (res > 0)
 201                 *offp += res;
 202 unlock:
 203         unlock_system_sleep(sleep_flags);
 204
 205         return res;
 206 }
 207
 208 struct compat_resume_swap_area {
 209         compat_loff_t offset;
 210         u32 dev;
 211 } __packed;
 212
 213 static int snapshot_set_swap_area(struct snapshot_data *data,
 214                 void __user *argp)
 215 {
 216         sector_t offset;
 217         dev_t swdev;
 218
 219         if (swsusp_swap_in_use())
 220                 return -EPERM;
 221
 222         if (in_compat_syscall()) {
 223                 struct compat_resume_swap_area swap_area;
 224
 225                 if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
 226                         return -EFAULT;
 227                 swdev = new_decode_dev(swap_area.dev);
 228                 offset = swap_area.offset;
 229         } else {
 230                 struct resume_swap_area swap_area;
 231
 232                 if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
 233                         return -EFAULT;
 234                 swdev = new_decode_dev(swap_area.dev);
 235                 offset = swap_area.offset;
 236         }
 237
 238         /*
 239          * User space encodes device types as two-byte values,
 240          * so we need to recode them
 241          */
 242         data->swap = swap_type_of(swdev, offset);
 243         if (data->swap < 0)
 244                 return swdev ? -ENODEV : -EINVAL;
 245         data->dev = swdev;
 246         return 0;
 247 }
 248
 249 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 250                                                         unsigned long arg)
 251 {
 252         int error = 0;
 253         struct snapshot_data *data;
 254         loff_t size;
 255         sector_t offset;
 256
 257         if (need_wait) {
 258                 wait_for_device_probe();
 259                 need_wait = false;
 260         }
 261
 262         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 263                 return -ENOTTY;
 264         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 265                 return -ENOTTY;
 266         if (!capable(CAP_SYS_ADMIN))
 267                 return -EPERM;
 268
 269         if (!mutex_trylock(&system_transition_mutex))
 270                 return -EBUSY;
 271
 272         lock_device_hotplug();
 273         data = filp->private_data;
 274
 275         switch (cmd) {
 276
 277         case SNAPSHOT_FREEZE:
 278                 if (data->frozen)
 279                         break;
 280
 281                 ksys_sync_helper();
 282
 283                 error = freeze_processes();
 284                 if (error)
 285                         break;
 286
 287                 error = create_basic_memory_bitmaps();
 288                 if (error)
 289                         thaw_processes();
 290                 else
 291                         data->frozen = true;
 292
 293                 break;
 294
 295         case SNAPSHOT_UNFREEZE:
 296                 if (!data->frozen || data->ready)
 297                         break;
 298                 pm_restore_gfp_mask();
 299                 free_basic_memory_bitmaps();
 300                 data->free_bitmaps = false;
 301                 thaw_processes();
 302                 data->frozen = false;
 303                 break;
 304
 305         case SNAPSHOT_CREATE_IMAGE:
 306                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 307                         error = -EPERM;
 308                         break;
 309                 }
 310                 pm_restore_gfp_mask();
 311                 error = hibernation_snapshot(data->platform_support);
 312                 if (!error) {
 313                         error = put_user(in_suspend, (int __user *)arg);
 314                         data->ready = !freezer_test_done && !error;
 315                         freezer_test_done = false;
 316                 }
 317                 break;
 318
 319         case SNAPSHOT_ATOMIC_RESTORE:
 320                 error = snapshot_write_finalize(&data->handle);
 321                 if (error)
 322                         break;
 323                 if (data->mode != O_WRONLY || !data->frozen ||
 324                     !snapshot_image_loaded(&data->handle)) {
 325                         error = -EPERM;
 326                         break;
 327                 }
 328                 error = hibernation_restore(data->platform_support);
 329                 break;
 330
 331         case SNAPSHOT_FREE:
 332                 swsusp_free();
 333                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 334                 data->ready = false;
 335                 /*
 336                  * It is necessary to thaw kernel threads here, because
 337                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 338                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 339                  * thawed, the preallocation of memory carried out by
 340                  * hibernation_snapshot() might run into problems (i.e. it
 341                  * might fail or even deadlock).
 342                  */
 343                 thaw_kernel_threads();
 344                 break;
 345
 346         case SNAPSHOT_PREF_IMAGE_SIZE:
 347                 image_size = arg;
 348                 break;
 349
 350         case SNAPSHOT_GET_IMAGE_SIZE:
 351                 if (!data->ready) {
 352                         error = -ENODATA;
 353                         break;
 354                 }
 355                 size = snapshot_get_image_size();
 356                 size <<= PAGE_SHIFT;
 357                 error = put_user(size, (loff_t __user *)arg);
 358                 break;
 359
 360         case SNAPSHOT_AVAIL_SWAP_SIZE:
 361                 size = count_swap_pages(data->swap, 1);
 362                 size <<= PAGE_SHIFT;
 363                 error = put_user(size, (loff_t __user *)arg);
 364                 break;
 365
 366         case SNAPSHOT_ALLOC_SWAP_PAGE:
 367                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 368                         error = -ENODEV;
 369                         break;
 370                 }
 371                 offset = alloc_swapdev_block(data->swap);
 372                 if (offset) {
 373                         offset <<= PAGE_SHIFT;
 374                         error = put_user(offset, (loff_t __user *)arg);
 375                 } else {
 376                         error = -ENOSPC;
 377                 }
 378                 break;
 379
 380         case SNAPSHOT_FREE_SWAP_PAGES:
 381                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 382                         error = -ENODEV;
 383                         break;
 384                 }
 385                 free_all_swap_pages(data->swap);
 386                 break;
 387
 388         case SNAPSHOT_S2RAM:
 389                 if (!data->frozen) {
 390                         error = -EPERM;
 391                         break;
 392                 }
 393                 /*
 394                  * Tasks are frozen and the notifiers have been called with
 395                  * PM_HIBERNATION_PREPARE
 396                  */
 397                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 398                 data->ready = false;
 399                 break;
 400
 401         case SNAPSHOT_PLATFORM_SUPPORT:
 402                 data->platform_support = !!arg;
 403                 break;
 404
 405         case SNAPSHOT_POWER_OFF:
 406                 if (data->platform_support)
 407                         error = hibernation_platform_enter();
 408                 break;
 409
 410         case SNAPSHOT_SET_SWAP_AREA:
 411                 error = snapshot_set_swap_area(data, (void __user *)arg);
 412                 break;
 413
 414         default:
 415                 error = -ENOTTY;
 416
 417         }
 418
 419         unlock_device_hotplug();
 420         mutex_unlock(&system_transition_mutex);
 421
 422         return error;
 423 }
 424
 425 #ifdef CONFIG_COMPAT
 426 static long
 427 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 428 {
 429         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 430
 431         switch (cmd) {
 432         case SNAPSHOT_GET_IMAGE_SIZE:
 433         case SNAPSHOT_AVAIL_SWAP_SIZE:
 434         case SNAPSHOT_ALLOC_SWAP_PAGE:
 435         case SNAPSHOT_CREATE_IMAGE:
 436         case SNAPSHOT_SET_SWAP_AREA:
 437                 return snapshot_ioctl(file, cmd,
 438                                       (unsigned long) compat_ptr(arg));
 439         default:
 440                 return snapshot_ioctl(file, cmd, arg);
 441         }
 442 }
 443 #endif /* CONFIG_COMPAT */
 444
 445 static const struct file_operations snapshot_fops = {
 446         .open = snapshot_open,
 447         .release = snapshot_release,
 448         .read = snapshot_read,
 449         .write = snapshot_write,
 450         .unlocked_ioctl = snapshot_ioctl,
 451 #ifdef CONFIG_COMPAT
 452         .compat_ioctl = snapshot_compat_ioctl,
 453 #endif
 454 };
 455
 456 static struct miscdevice snapshot_device = {
 457         .minor = SNAPSHOT_MINOR,
 458         .name = "snapshot",
 459         .fops = &snapshot_fops,
 460 };
 461
 462 static int __init snapshot_device_init(void)
 463 {
 464         return misc_register(&snapshot_device);
 465 };
 466
 467 device_initcall(snapshot_device_init);