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