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
  30 #define SNAPSHOT_MINOR  231
  31
  32 static struct snapshot_data {
  33         struct snapshot_handle handle;
  34         int swap;
  35         int mode;
  36         bool frozen;
  37         bool ready;
  38         bool platform_support;
  39         bool free_bitmaps;
  40 } snapshot_state;
  41
  42 atomic_t snapshot_device_available = ATOMIC_INIT(1);
  43
  44 static int snapshot_open(struct inode *inode, struct file *filp)
  45 {
  46         struct snapshot_data *data;
  47         int error, nr_calls = 0;
  48
  49         if (!hibernation_available())
  50                 return -EPERM;
  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, -1, &nr_calls);
  75                 if (error)
  76                         __pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
  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, -1, &nr_calls);
  87                 if (!error) {
  88                         error = create_basic_memory_bitmaps();
  89                         data->free_bitmaps = !error;
  90                 } else
  91                         nr_calls--;
  92
  93                 if (error)
  94                         __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
  95         }
  96         if (error)
  97                 atomic_inc(&snapshot_device_available);
  98
  99         data->frozen = false;
 100         data->ready = false;
 101         data->platform_support = false;
 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         data = filp->private_data;
 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         atomic_inc(&snapshot_device_available);
 128
 129         unlock_system_sleep();
 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         struct snapshot_data *data;
 138         ssize_t res;
 139         loff_t pg_offp = *offp & ~PAGE_MASK;
 140
 141         lock_system_sleep();
 142
 143         data = filp->private_data;
 144         if (!data->ready) {
 145                 res = -ENODATA;
 146                 goto Unlock;
 147         }
 148         if (!pg_offp) { /* on page boundary? */
 149                 res = snapshot_read_next(&data->handle);
 150                 if (res <= 0)
 151                         goto Unlock;
 152         } else {
 153                 res = PAGE_SIZE - pg_offp;
 154         }
 155
 156         res = simple_read_from_buffer(buf, count, &pg_offp,
 157                         data_of(data->handle), res);
 158         if (res > 0)
 159                 *offp += res;
 160
 161  Unlock:
 162         unlock_system_sleep();
 163
 164         return res;
 165 }
 166
 167 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 168                               size_t count, loff_t *offp)
 169 {
 170         struct snapshot_data *data;
 171         ssize_t res;
 172         loff_t pg_offp = *offp & ~PAGE_MASK;
 173
 174         lock_system_sleep();
 175
 176         data = filp->private_data;
 177
 178         if (!pg_offp) {
 179                 res = snapshot_write_next(&data->handle);
 180                 if (res <= 0)
 181                         goto unlock;
 182         } else {
 183                 res = PAGE_SIZE - pg_offp;
 184         }
 185
 186         if (!data_of(data->handle)) {
 187                 res = -EINVAL;
 188                 goto unlock;
 189         }
 190
 191         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 192                         buf, count);
 193         if (res > 0)
 194                 *offp += res;
 195 unlock:
 196         unlock_system_sleep();
 197
 198         return res;
 199 }
 200
 201 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 202                                                         unsigned long arg)
 203 {
 204         int error = 0;
 205         struct snapshot_data *data;
 206         loff_t size;
 207         sector_t offset;
 208
 209         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 210                 return -ENOTTY;
 211         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 212                 return -ENOTTY;
 213         if (!capable(CAP_SYS_ADMIN))
 214                 return -EPERM;
 215
 216         if (!mutex_trylock(&system_transition_mutex))
 217                 return -EBUSY;
 218
 219         lock_device_hotplug();
 220         data = filp->private_data;
 221
 222         switch (cmd) {
 223
 224         case SNAPSHOT_FREEZE:
 225                 if (data->frozen)
 226                         break;
 227
 228                 ksys_sync_helper();
 229
 230                 error = freeze_processes();
 231                 if (error)
 232                         break;
 233
 234                 error = create_basic_memory_bitmaps();
 235                 if (error)
 236                         thaw_processes();
 237                 else
 238                         data->frozen = true;
 239
 240                 break;
 241
 242         case SNAPSHOT_UNFREEZE:
 243                 if (!data->frozen || data->ready)
 244                         break;
 245                 pm_restore_gfp_mask();
 246                 free_basic_memory_bitmaps();
 247                 data->free_bitmaps = false;
 248                 thaw_processes();
 249                 data->frozen = false;
 250                 break;
 251
 252         case SNAPSHOT_CREATE_IMAGE:
 253                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 254                         error = -EPERM;
 255                         break;
 256                 }
 257                 pm_restore_gfp_mask();
 258                 error = hibernation_snapshot(data->platform_support);
 259                 if (!error) {
 260                         error = put_user(in_suspend, (int __user *)arg);
 261                         data->ready = !freezer_test_done && !error;
 262                         freezer_test_done = false;
 263                 }
 264                 break;
 265
 266         case SNAPSHOT_ATOMIC_RESTORE:
 267                 snapshot_write_finalize(&data->handle);
 268                 if (data->mode != O_WRONLY || !data->frozen ||
 269                     !snapshot_image_loaded(&data->handle)) {
 270                         error = -EPERM;
 271                         break;
 272                 }
 273                 error = hibernation_restore(data->platform_support);
 274                 break;
 275
 276         case SNAPSHOT_FREE:
 277                 swsusp_free();
 278                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 279                 data->ready = false;
 280                 /*
 281                  * It is necessary to thaw kernel threads here, because
 282                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 283                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 284                  * thawed, the preallocation of memory carried out by
 285                  * hibernation_snapshot() might run into problems (i.e. it
 286                  * might fail or even deadlock).
 287                  */
 288                 thaw_kernel_threads();
 289                 break;
 290
 291         case SNAPSHOT_PREF_IMAGE_SIZE:
 292                 image_size = arg;
 293                 break;
 294
 295         case SNAPSHOT_GET_IMAGE_SIZE:
 296                 if (!data->ready) {
 297                         error = -ENODATA;
 298                         break;
 299                 }
 300                 size = snapshot_get_image_size();
 301                 size <<= PAGE_SHIFT;
 302                 error = put_user(size, (loff_t __user *)arg);
 303                 break;
 304
 305         case SNAPSHOT_AVAIL_SWAP_SIZE:
 306                 size = count_swap_pages(data->swap, 1);
 307                 size <<= PAGE_SHIFT;
 308                 error = put_user(size, (loff_t __user *)arg);
 309                 break;
 310
 311         case SNAPSHOT_ALLOC_SWAP_PAGE:
 312                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 313                         error = -ENODEV;
 314                         break;
 315                 }
 316                 offset = alloc_swapdev_block(data->swap);
 317                 if (offset) {
 318                         offset <<= PAGE_SHIFT;
 319                         error = put_user(offset, (loff_t __user *)arg);
 320                 } else {
 321                         error = -ENOSPC;
 322                 }
 323                 break;
 324
 325         case SNAPSHOT_FREE_SWAP_PAGES:
 326                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 327                         error = -ENODEV;
 328                         break;
 329                 }
 330                 free_all_swap_pages(data->swap);
 331                 break;
 332
 333         case SNAPSHOT_S2RAM:
 334                 if (!data->frozen) {
 335                         error = -EPERM;
 336                         break;
 337                 }
 338                 /*
 339                  * Tasks are frozen and the notifiers have been called with
 340                  * PM_HIBERNATION_PREPARE
 341                  */
 342                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 343                 data->ready = false;
 344                 break;
 345
 346         case SNAPSHOT_PLATFORM_SUPPORT:
 347                 data->platform_support = !!arg;
 348                 break;
 349
 350         case SNAPSHOT_POWER_OFF:
 351                 if (data->platform_support)
 352                         error = hibernation_platform_enter();
 353                 break;
 354
 355         case SNAPSHOT_SET_SWAP_AREA:
 356                 if (swsusp_swap_in_use()) {
 357                         error = -EPERM;
 358                 } else {
 359                         struct resume_swap_area swap_area;
 360                         dev_t swdev;
 361
 362                         error = copy_from_user(&swap_area, (void __user *)arg,
 363                                         sizeof(struct resume_swap_area));
 364                         if (error) {
 365                                 error = -EFAULT;
 366                                 break;
 367                         }
 368
 369                         /*
 370                          * User space encodes device types as two-byte values,
 371                          * so we need to recode them
 372                          */
 373                         swdev = new_decode_dev(swap_area.dev);
 374                         if (swdev) {
 375                                 offset = swap_area.offset;
 376                                 data->swap = swap_type_of(swdev, offset, NULL);
 377                                 if (data->swap < 0)
 378                                         error = -ENODEV;
 379                         } else {
 380                                 data->swap = -1;
 381                                 error = -EINVAL;
 382                         }
 383                 }
 384                 break;
 385
 386         default:
 387                 error = -ENOTTY;
 388
 389         }
 390
 391         unlock_device_hotplug();
 392         mutex_unlock(&system_transition_mutex);
 393
 394         return error;
 395 }
 396
 397 #ifdef CONFIG_COMPAT
 398
 399 struct compat_resume_swap_area {
 400         compat_loff_t offset;
 401         u32 dev;
 402 } __packed;
 403
 404 static long
 405 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 406 {
 407         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 408
 409         switch (cmd) {
 410         case SNAPSHOT_GET_IMAGE_SIZE:
 411         case SNAPSHOT_AVAIL_SWAP_SIZE:
 412         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 413                 compat_loff_t __user *uoffset = compat_ptr(arg);
 414                 loff_t offset;
 415                 mm_segment_t old_fs;
 416                 int err;
 417
 418                 old_fs = get_fs();
 419                 set_fs(KERNEL_DS);
 420                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 421                 set_fs(old_fs);
 422                 if (!err && put_user(offset, uoffset))
 423                         err = -EFAULT;
 424                 return err;
 425         }
 426
 427         case SNAPSHOT_CREATE_IMAGE:
 428                 return snapshot_ioctl(file, cmd,
 429                                       (unsigned long) compat_ptr(arg));
 430
 431         case SNAPSHOT_SET_SWAP_AREA: {
 432                 struct compat_resume_swap_area __user *u_swap_area =
 433                         compat_ptr(arg);
 434                 struct resume_swap_area swap_area;
 435                 mm_segment_t old_fs;
 436                 int err;
 437
 438                 err = get_user(swap_area.offset, &u_swap_area->offset);
 439                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 440                 if (err)
 441                         return -EFAULT;
 442                 old_fs = get_fs();
 443                 set_fs(KERNEL_DS);
 444                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 445                                      (unsigned long) &swap_area);
 446                 set_fs(old_fs);
 447                 return err;
 448         }
 449
 450         default:
 451                 return snapshot_ioctl(file, cmd, arg);
 452         }
 453 }
 454
 455 #endif /* CONFIG_COMPAT */
 456
 457 static const struct file_operations snapshot_fops = {
 458         .open = snapshot_open,
 459         .release = snapshot_release,
 460         .read = snapshot_read,
 461         .write = snapshot_write,
 462         .llseek = no_llseek,
 463         .unlocked_ioctl = snapshot_ioctl,
 464 #ifdef CONFIG_COMPAT
 465         .compat_ioctl = snapshot_compat_ioctl,
 466 #endif
 467 };
 468
 469 static struct miscdevice snapshot_device = {
 470         .minor = SNAPSHOT_MINOR,
 471         .name = "snapshot",
 472         .fops = &snapshot_fops,
 473 };
 474
 475 static int __init snapshot_device_init(void)
 476 {
 477         return misc_register(&snapshot_device);
 478 };
 479
 480 device_initcall(snapshot_device_init);