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 static struct snapshot_data {
  31         struct snapshot_handle handle;
  32         int swap;
  33         int mode;
  34         bool frozen;
  35         bool ready;
  36         bool platform_support;
  37         bool free_bitmaps;
  38         struct inode *bd_inode;
  39 } snapshot_state;
  40
  41 int is_hibernate_resume_dev(const struct inode *bd_inode)
  42 {
  43         return hibernation_available() && snapshot_state.bd_inode == bd_inode;
  44 }
  45
  46 static int snapshot_open(struct inode *inode, struct file *filp)
  47 {
  48         struct snapshot_data *data;
  49         int error, nr_calls = 0;
  50
  51         if (!hibernation_available())
  52                 return -EPERM;
  53
  54         lock_system_sleep();
  55
  56         if (!hibernate_acquire()) {
  57                 error = -EBUSY;
  58                 goto Unlock;
  59         }
  60
  61         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
  62                 hibernate_release();
  63                 error = -ENOSYS;
  64                 goto Unlock;
  65         }
  66         nonseekable_open(inode, filp);
  67         data = &snapshot_state;
  68         filp->private_data = data;
  69         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  70         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  71                 /* Hibernating.  The image device should be accessible. */
  72                 data->swap = swsusp_resume_device ?
  73                         swap_type_of(swsusp_resume_device, 0, NULL) : -1;
  74                 data->mode = O_RDONLY;
  75                 data->free_bitmaps = false;
  76                 error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
  77                 if (error)
  78                         __pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
  79         } else {
  80                 /*
  81                  * Resuming.  We may need to wait for the image device to
  82                  * appear.
  83                  */
  84                 wait_for_device_probe();
  85
  86                 data->swap = -1;
  87                 data->mode = O_WRONLY;
  88                 error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
  89                 if (!error) {
  90                         error = create_basic_memory_bitmaps();
  91                         data->free_bitmaps = !error;
  92                 } else
  93                         nr_calls--;
  94
  95                 if (error)
  96                         __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
  97         }
  98         if (error)
  99                 hibernate_release();
 100
 101         data->frozen = false;
 102         data->ready = false;
 103         data->platform_support = false;
 104         data->bd_inode = NULL;
 105
 106  Unlock:
 107         unlock_system_sleep();
 108
 109         return error;
 110 }
 111
 112 static int snapshot_release(struct inode *inode, struct file *filp)
 113 {
 114         struct snapshot_data *data;
 115
 116         lock_system_sleep();
 117
 118         swsusp_free();
 119         data = filp->private_data;
 120         data->bd_inode = NULL;
 121         free_all_swap_pages(data->swap);
 122         if (data->frozen) {
 123                 pm_restore_gfp_mask();
 124                 free_basic_memory_bitmaps();
 125                 thaw_processes();
 126         } else if (data->free_bitmaps) {
 127                 free_basic_memory_bitmaps();
 128         }
 129         pm_notifier_call_chain(data->mode == O_RDONLY ?
 130                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 131         hibernate_release();
 132
 133         unlock_system_sleep();
 134
 135         return 0;
 136 }
 137
 138 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 139                              size_t count, loff_t *offp)
 140 {
 141         struct snapshot_data *data;
 142         ssize_t res;
 143         loff_t pg_offp = *offp & ~PAGE_MASK;
 144
 145         lock_system_sleep();
 146
 147         data = filp->private_data;
 148         if (!data->ready) {
 149                 res = -ENODATA;
 150                 goto Unlock;
 151         }
 152         if (!pg_offp) { /* on page boundary? */
 153                 res = snapshot_read_next(&data->handle);
 154                 if (res <= 0)
 155                         goto Unlock;
 156         } else {
 157                 res = PAGE_SIZE - pg_offp;
 158         }
 159
 160         res = simple_read_from_buffer(buf, count, &pg_offp,
 161                         data_of(data->handle), res);
 162         if (res > 0)
 163                 *offp += res;
 164
 165  Unlock:
 166         unlock_system_sleep();
 167
 168         return res;
 169 }
 170
 171 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 172                               size_t count, loff_t *offp)
 173 {
 174         struct snapshot_data *data;
 175         ssize_t res;
 176         loff_t pg_offp = *offp & ~PAGE_MASK;
 177
 178         lock_system_sleep();
 179
 180         data = filp->private_data;
 181
 182         if (!pg_offp) {
 183                 res = snapshot_write_next(&data->handle);
 184                 if (res <= 0)
 185                         goto unlock;
 186         } else {
 187                 res = PAGE_SIZE - pg_offp;
 188         }
 189
 190         if (!data_of(data->handle)) {
 191                 res = -EINVAL;
 192                 goto unlock;
 193         }
 194
 195         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 196                         buf, count);
 197         if (res > 0)
 198                 *offp += res;
 199 unlock:
 200         unlock_system_sleep();
 201
 202         return res;
 203 }
 204
 205 struct compat_resume_swap_area {
 206         compat_loff_t offset;
 207         u32 dev;
 208 } __packed;
 209
 210 static int snapshot_set_swap_area(struct snapshot_data *data,
 211                 void __user *argp)
 212 {
 213         struct block_device *bdev;
 214         sector_t offset;
 215         dev_t swdev;
 216
 217         if (swsusp_swap_in_use())
 218                 return -EPERM;
 219
 220         if (in_compat_syscall()) {
 221                 struct compat_resume_swap_area swap_area;
 222
 223                 if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
 224                         return -EFAULT;
 225                 swdev = new_decode_dev(swap_area.dev);
 226                 offset = swap_area.offset;
 227         } else {
 228                 struct resume_swap_area swap_area;
 229
 230                 if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
 231                         return -EFAULT;
 232                 swdev = new_decode_dev(swap_area.dev);
 233                 offset = swap_area.offset;
 234         }
 235
 236         /*
 237          * User space encodes device types as two-byte values,
 238          * so we need to recode them
 239          */
 240         if (!swdev) {
 241                 data->swap = -1;
 242                 return -EINVAL;
 243         }
 244         data->swap = swap_type_of(swdev, offset, &bdev);
 245         if (data->swap < 0)
 246                 return -ENODEV;
 247
 248         data->bd_inode = bdev->bd_inode;
 249         bdput(bdev);
 250         return 0;
 251 }
 252
 253 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 254                                                         unsigned long arg)
 255 {
 256         int error = 0;
 257         struct snapshot_data *data;
 258         loff_t size;
 259         sector_t offset;
 260
 261         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 262                 return -ENOTTY;
 263         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 264                 return -ENOTTY;
 265         if (!capable(CAP_SYS_ADMIN))
 266                 return -EPERM;
 267
 268         if (!mutex_trylock(&system_transition_mutex))
 269                 return -EBUSY;
 270
 271         lock_device_hotplug();
 272         data = filp->private_data;
 273
 274         switch (cmd) {
 275
 276         case SNAPSHOT_FREEZE:
 277                 if (data->frozen)
 278                         break;
 279
 280                 ksys_sync_helper();
 281
 282                 error = freeze_processes();
 283                 if (error)
 284                         break;
 285
 286                 error = create_basic_memory_bitmaps();
 287                 if (error)
 288                         thaw_processes();
 289                 else
 290                         data->frozen = true;
 291
 292                 break;
 293
 294         case SNAPSHOT_UNFREEZE:
 295                 if (!data->frozen || data->ready)
 296                         break;
 297                 pm_restore_gfp_mask();
 298                 free_basic_memory_bitmaps();
 299                 data->free_bitmaps = false;
 300                 thaw_processes();
 301                 data->frozen = false;
 302                 break;
 303
 304         case SNAPSHOT_CREATE_IMAGE:
 305                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 306                         error = -EPERM;
 307                         break;
 308                 }
 309                 pm_restore_gfp_mask();
 310                 error = hibernation_snapshot(data->platform_support);
 311                 if (!error) {
 312                         error = put_user(in_suspend, (int __user *)arg);
 313                         data->ready = !freezer_test_done && !error;
 314                         freezer_test_done = false;
 315                 }
 316                 break;
 317
 318         case SNAPSHOT_ATOMIC_RESTORE:
 319                 snapshot_write_finalize(&data->handle);
 320                 if (data->mode != O_WRONLY || !data->frozen ||
 321                     !snapshot_image_loaded(&data->handle)) {
 322                         error = -EPERM;
 323                         break;
 324                 }
 325                 error = hibernation_restore(data->platform_support);
 326                 break;
 327
 328         case SNAPSHOT_FREE:
 329                 swsusp_free();
 330                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 331                 data->ready = false;
 332                 /*
 333                  * It is necessary to thaw kernel threads here, because
 334                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 335                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 336                  * thawed, the preallocation of memory carried out by
 337                  * hibernation_snapshot() might run into problems (i.e. it
 338                  * might fail or even deadlock).
 339                  */
 340                 thaw_kernel_threads();
 341                 break;
 342
 343         case SNAPSHOT_PREF_IMAGE_SIZE:
 344                 image_size = arg;
 345                 break;
 346
 347         case SNAPSHOT_GET_IMAGE_SIZE:
 348                 if (!data->ready) {
 349                         error = -ENODATA;
 350                         break;
 351                 }
 352                 size = snapshot_get_image_size();
 353                 size <<= PAGE_SHIFT;
 354                 error = put_user(size, (loff_t __user *)arg);
 355                 break;
 356
 357         case SNAPSHOT_AVAIL_SWAP_SIZE:
 358                 size = count_swap_pages(data->swap, 1);
 359                 size <<= PAGE_SHIFT;
 360                 error = put_user(size, (loff_t __user *)arg);
 361                 break;
 362
 363         case SNAPSHOT_ALLOC_SWAP_PAGE:
 364                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 365                         error = -ENODEV;
 366                         break;
 367                 }
 368                 offset = alloc_swapdev_block(data->swap);
 369                 if (offset) {
 370                         offset <<= PAGE_SHIFT;
 371                         error = put_user(offset, (loff_t __user *)arg);
 372                 } else {
 373                         error = -ENOSPC;
 374                 }
 375                 break;
 376
 377         case SNAPSHOT_FREE_SWAP_PAGES:
 378                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 379                         error = -ENODEV;
 380                         break;
 381                 }
 382                 free_all_swap_pages(data->swap);
 383                 break;
 384
 385         case SNAPSHOT_S2RAM:
 386                 if (!data->frozen) {
 387                         error = -EPERM;
 388                         break;
 389                 }
 390                 /*
 391                  * Tasks are frozen and the notifiers have been called with
 392                  * PM_HIBERNATION_PREPARE
 393                  */
 394                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 395                 data->ready = false;
 396                 break;
 397
 398         case SNAPSHOT_PLATFORM_SUPPORT:
 399                 data->platform_support = !!arg;
 400                 break;
 401
 402         case SNAPSHOT_POWER_OFF:
 403                 if (data->platform_support)
 404                         error = hibernation_platform_enter();
 405                 break;
 406
 407         case SNAPSHOT_SET_SWAP_AREA:
 408                 error = snapshot_set_swap_area(data, (void __user *)arg);
 409                 break;
 410
 411         default:
 412                 error = -ENOTTY;
 413
 414         }
 415
 416         unlock_device_hotplug();
 417         mutex_unlock(&system_transition_mutex);
 418
 419         return error;
 420 }
 421
 422 #ifdef CONFIG_COMPAT
 423 static long
 424 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 425 {
 426         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 427
 428         switch (cmd) {
 429         case SNAPSHOT_GET_IMAGE_SIZE:
 430         case SNAPSHOT_AVAIL_SWAP_SIZE:
 431         case SNAPSHOT_ALLOC_SWAP_PAGE:
 432         case SNAPSHOT_CREATE_IMAGE:
 433         case SNAPSHOT_SET_SWAP_AREA:
 434                 return snapshot_ioctl(file, cmd,
 435                                       (unsigned long) compat_ptr(arg));
 436         default:
 437                 return snapshot_ioctl(file, cmd, arg);
 438         }
 439 }
 440 #endif /* CONFIG_COMPAT */
 441
 442 static const struct file_operations snapshot_fops = {
 443         .open = snapshot_open,
 444         .release = snapshot_release,
 445         .read = snapshot_read,
 446         .write = snapshot_write,
 447         .llseek = no_llseek,
 448         .unlocked_ioctl = snapshot_ioctl,
 449 #ifdef CONFIG_COMPAT
 450         .compat_ioctl = snapshot_compat_ioctl,
 451 #endif
 452 };
 453
 454 static struct miscdevice snapshot_device = {
 455         .minor = SNAPSHOT_MINOR,
 456         .name = "snapshot",
 457         .fops = &snapshot_fops,
 458 };
 459
 460 static int __init snapshot_device_init(void)
 461 {
 462         return misc_register(&snapshot_device);
 463 };
 464
 465 device_initcall(snapshot_device_init);