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 static bool need_wait;
  30
  31 static struct snapshot_data {
  32         struct snapshot_handle handle;
  33         int swap;
  34         int mode;
  35         bool frozen;
  36         bool ready;
  37         bool platform_support;
  38         bool free_bitmaps;
  39         dev_t dev;
  40 } snapshot_state;
  41
  42 int is_hibernate_resume_dev(dev_t dev)
  43 {
  44         return hibernation_available() && snapshot_state.dev == dev;
  45 }
  46
  47 static int snapshot_open(struct inode *inode, struct file *filp)
  48 {
  49         struct snapshot_data *data;
  50         int error;
  51
  52         if (!hibernation_available())
  53                 return -EPERM;
  54
  55         lock_system_sleep();
  56
  57         if (!hibernate_acquire()) {
  58                 error = -EBUSY;
  59                 goto Unlock;
  60         }
  61
  62         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
  63                 hibernate_release();
  64                 error = -ENOSYS;
  65                 goto Unlock;
  66         }
  67         nonseekable_open(inode, filp);
  68         data = &snapshot_state;
  69         filp->private_data = data;
  70         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  71         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  72                 /* Hibernating.  The image device should be accessible. */
  73                 data->swap = swap_type_of(swsusp_resume_device, 0);
  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                 need_wait = true;
  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->dev = 0;
  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->dev = 0;
 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         if (need_wait) {
 173                 wait_for_device_probe();
 174                 need_wait = false;
 175         }
 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 (need_wait) {
 254                 wait_for_device_probe();
 255                 need_wait = false;
 256         }
 257
 258         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 259                 return -ENOTTY;
 260         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 261                 return -ENOTTY;
 262         if (!capable(CAP_SYS_ADMIN))
 263                 return -EPERM;
 264
 265         if (!mutex_trylock(&system_transition_mutex))
 266                 return -EBUSY;
 267
 268         lock_device_hotplug();
 269         data = filp->private_data;
 270
 271         switch (cmd) {
 272
 273         case SNAPSHOT_FREEZE:
 274                 if (data->frozen)
 275                         break;
 276
 277                 ksys_sync_helper();
 278
 279                 error = freeze_processes();
 280                 if (error)
 281                         break;
 282
 283                 error = create_basic_memory_bitmaps();
 284                 if (error)
 285                         thaw_processes();
 286                 else
 287                         data->frozen = true;
 288
 289                 break;
 290
 291         case SNAPSHOT_UNFREEZE:
 292                 if (!data->frozen || data->ready)
 293                         break;
 294                 pm_restore_gfp_mask();
 295                 free_basic_memory_bitmaps();
 296                 data->free_bitmaps = false;
 297                 thaw_processes();
 298                 data->frozen = false;
 299                 break;
 300
 301         case SNAPSHOT_CREATE_IMAGE:
 302                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 303                         error = -EPERM;
 304                         break;
 305                 }
 306                 pm_restore_gfp_mask();
 307                 error = hibernation_snapshot(data->platform_support);
 308                 if (!error) {
 309                         error = put_user(in_suspend, (int __user *)arg);
 310                         data->ready = !freezer_test_done && !error;
 311                         freezer_test_done = false;
 312                 }
 313                 break;
 314
 315         case SNAPSHOT_ATOMIC_RESTORE:
 316                 snapshot_write_finalize(&data->handle);
 317                 if (data->mode != O_WRONLY || !data->frozen ||
 318                     !snapshot_image_loaded(&data->handle)) {
 319                         error = -EPERM;
 320                         break;
 321                 }
 322                 error = hibernation_restore(data->platform_support);
 323                 break;
 324
 325         case SNAPSHOT_FREE:
 326                 swsusp_free();
 327                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 328                 data->ready = false;
 329                 /*
 330                  * It is necessary to thaw kernel threads here, because
 331                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 332                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 333                  * thawed, the preallocation of memory carried out by
 334                  * hibernation_snapshot() might run into problems (i.e. it
 335                  * might fail or even deadlock).
 336                  */
 337                 thaw_kernel_threads();
 338                 break;
 339
 340         case SNAPSHOT_PREF_IMAGE_SIZE:
 341                 image_size = arg;
 342                 break;
 343
 344         case SNAPSHOT_GET_IMAGE_SIZE:
 345                 if (!data->ready) {
 346                         error = -ENODATA;
 347                         break;
 348                 }
 349                 size = snapshot_get_image_size();
 350                 size <<= PAGE_SHIFT;
 351                 error = put_user(size, (loff_t __user *)arg);
 352                 break;
 353
 354         case SNAPSHOT_AVAIL_SWAP_SIZE:
 355                 size = count_swap_pages(data->swap, 1);
 356                 size <<= PAGE_SHIFT;
 357                 error = put_user(size, (loff_t __user *)arg);
 358                 break;
 359
 360         case SNAPSHOT_ALLOC_SWAP_PAGE:
 361                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 362                         error = -ENODEV;
 363                         break;
 364                 }
 365                 offset = alloc_swapdev_block(data->swap);
 366                 if (offset) {
 367                         offset <<= PAGE_SHIFT;
 368                         error = put_user(offset, (loff_t __user *)arg);
 369                 } else {
 370                         error = -ENOSPC;
 371                 }
 372                 break;
 373
 374         case SNAPSHOT_FREE_SWAP_PAGES:
 375                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 376                         error = -ENODEV;
 377                         break;
 378                 }
 379                 free_all_swap_pages(data->swap);
 380                 break;
 381
 382         case SNAPSHOT_S2RAM:
 383                 if (!data->frozen) {
 384                         error = -EPERM;
 385                         break;
 386                 }
 387                 /*
 388                  * Tasks are frozen and the notifiers have been called with
 389                  * PM_HIBERNATION_PREPARE
 390                  */
 391                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 392                 data->ready = false;
 393                 break;
 394
 395         case SNAPSHOT_PLATFORM_SUPPORT:
 396                 data->platform_support = !!arg;
 397                 break;
 398
 399         case SNAPSHOT_POWER_OFF:
 400                 if (data->platform_support)
 401                         error = hibernation_platform_enter();
 402                 break;
 403
 404         case SNAPSHOT_SET_SWAP_AREA:
 405                 error = snapshot_set_swap_area(data, (void __user *)arg);
 406                 break;
 407
 408         default:
 409                 error = -ENOTTY;
 410
 411         }
 412
 413         unlock_device_hotplug();
 414         mutex_unlock(&system_transition_mutex);
 415
 416         return error;
 417 }
 418
 419 #ifdef CONFIG_COMPAT
 420 static long
 421 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 422 {
 423         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 424
 425         switch (cmd) {
 426         case SNAPSHOT_GET_IMAGE_SIZE:
 427         case SNAPSHOT_AVAIL_SWAP_SIZE:
 428         case SNAPSHOT_ALLOC_SWAP_PAGE:
 429         case SNAPSHOT_CREATE_IMAGE:
 430         case SNAPSHOT_SET_SWAP_AREA:
 431                 return snapshot_ioctl(file, cmd,
 432                                       (unsigned long) compat_ptr(arg));
 433         default:
 434                 return snapshot_ioctl(file, cmd, arg);
 435         }
 436 }
 437 #endif /* CONFIG_COMPAT */
 438
 439 static const struct file_operations snapshot_fops = {
 440         .open = snapshot_open,
 441         .release = snapshot_release,
 442         .read = snapshot_read,
 443         .write = snapshot_write,
 444         .llseek = no_llseek,
 445         .unlocked_ioctl = snapshot_ioctl,
 446 #ifdef CONFIG_COMPAT
 447         .compat_ioctl = snapshot_compat_ioctl,
 448 #endif
 449 };
 450
 451 static struct miscdevice snapshot_device = {
 452         .minor = SNAPSHOT_MINOR,
 453         .name = "snapshot",
 454         .fops = &snapshot_fops,
 455 };
 456
 457 static int __init snapshot_device_init(void)
 458 {
 459         return misc_register(&snapshot_device);
 460 };
 461
 462 device_initcall(snapshot_device_init);