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