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