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