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