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 unsigned int sleep_flags; 51 int error; 52 53 if (!hibernation_available()) 54 return -EPERM; 55 56 sleep_flags = lock_system_sleep(); 57 58 if (!hibernate_acquire()) { 59 error = -EBUSY; 60 goto Unlock; 61 } 62 63 if ((filp->f_flags & O_ACCMODE) == O_RDWR) { 64 hibernate_release(); 65 error = -ENOSYS; 66 goto Unlock; 67 } 68 nonseekable_open(inode, filp); 69 data = &snapshot_state; 70 filp->private_data = data; 71 memset(&data->handle, 0, sizeof(struct snapshot_handle)); 72 if ((filp->f_flags & O_ACCMODE) == O_RDONLY) { 73 /* Hibernating. The image device should be accessible. */ 74 data->swap = pin_hibernation_swap_type(swsusp_resume_device, 0); 75 data->mode = O_RDONLY; 76 data->free_bitmaps = false; 77 error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION); 78 } else { 79 /* 80 * Resuming. We may need to wait for the image device to 81 * appear. 82 */ 83 need_wait = true; 84 85 data->swap = -1; 86 data->mode = O_WRONLY; 87 error = pm_notifier_call_chain_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE); 88 if (!error) { 89 error = create_basic_memory_bitmaps(); 90 data->free_bitmaps = !error; 91 } 92 } 93 if (error) { 94 unpin_hibernation_swap_type(data->swap); 95 hibernate_release(); 96 } 97 98 data->frozen = false; 99 data->ready = false; 100 data->platform_support = false; 101 data->dev = 0; 102 103 Unlock: 104 unlock_system_sleep(sleep_flags); 105 106 return error; 107 } 108 109 static int snapshot_release(struct inode *inode, struct file *filp) 110 { 111 struct snapshot_data *data; 112 unsigned int sleep_flags; 113 114 sleep_flags = lock_system_sleep(); 115 116 swsusp_free(); 117 data = filp->private_data; 118 data->dev = 0; 119 free_all_swap_pages(data->swap); 120 unpin_hibernation_swap_type(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(sleep_flags); 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 loff_t pg_offp = *offp & ~PAGE_MASK; 141 struct snapshot_data *data; 142 unsigned int sleep_flags; 143 ssize_t res; 144 145 sleep_flags = lock_system_sleep(); 146 147 data = filp->private_data; 148 if (!data->ready) { 149 res = -ENODATA; 150 goto Unlock; 151 } 152 if (!pg_offp) { /* on page boundary? */ 153 res = snapshot_read_next(&data->handle); 154 if (res <= 0) 155 goto Unlock; 156 } else { 157 res = PAGE_SIZE - pg_offp; 158 } 159 160 res = simple_read_from_buffer(buf, count, &pg_offp, 161 data_of(data->handle), res); 162 if (res > 0) 163 *offp += res; 164 165 Unlock: 166 unlock_system_sleep(sleep_flags); 167 168 return res; 169 } 170 171 static ssize_t snapshot_write(struct file *filp, const char __user *buf, 172 size_t count, loff_t *offp) 173 { 174 loff_t pg_offp = *offp & ~PAGE_MASK; 175 struct snapshot_data *data; 176 unsigned long sleep_flags; 177 ssize_t res; 178 179 if (need_wait) { 180 wait_for_device_probe(); 181 need_wait = false; 182 } 183 184 sleep_flags = lock_system_sleep(); 185 186 data = filp->private_data; 187 188 if (!pg_offp) { 189 res = snapshot_write_next(&data->handle); 190 if (res <= 0) 191 goto unlock; 192 } else { 193 res = PAGE_SIZE; 194 } 195 196 if (!data_of(data->handle)) { 197 res = -EINVAL; 198 goto unlock; 199 } 200 201 res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp, 202 buf, count); 203 if (res > 0) 204 *offp += res; 205 unlock: 206 unlock_system_sleep(sleep_flags); 207 208 return res; 209 } 210 211 struct compat_resume_swap_area { 212 compat_loff_t offset; 213 u32 dev; 214 } __packed; 215 216 static int snapshot_set_swap_area(struct snapshot_data *data, 217 void __user *argp) 218 { 219 sector_t offset; 220 dev_t swdev; 221 222 if (swsusp_swap_in_use()) 223 return -EPERM; 224 225 if (in_compat_syscall()) { 226 struct compat_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 } else { 233 struct resume_swap_area swap_area; 234 235 if (copy_from_user(&swap_area, argp, sizeof(swap_area))) 236 return -EFAULT; 237 swdev = new_decode_dev(swap_area.dev); 238 offset = swap_area.offset; 239 } 240 241 /* 242 * Unpin the swap device if a swap area was already 243 * set by SNAPSHOT_SET_SWAP_AREA. 244 */ 245 unpin_hibernation_swap_type(data->swap); 246 247 /* 248 * User space encodes device types as two-byte values, 249 * so we need to recode them 250 */ 251 data->swap = pin_hibernation_swap_type(swdev, offset); 252 if (data->swap < 0) 253 return swdev ? -ENODEV : -EINVAL; 254 data->dev = swdev; 255 return 0; 256 } 257 258 static long snapshot_ioctl(struct file *filp, unsigned int cmd, 259 unsigned long arg) 260 { 261 int error = 0; 262 struct snapshot_data *data; 263 loff_t size; 264 sector_t offset; 265 266 if (need_wait) { 267 wait_for_device_probe(); 268 need_wait = false; 269 } 270 271 if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC) 272 return -ENOTTY; 273 if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR) 274 return -ENOTTY; 275 if (!capable(CAP_SYS_ADMIN)) 276 return -EPERM; 277 278 if (!mutex_trylock(&system_transition_mutex)) 279 return -EBUSY; 280 281 lock_device_hotplug(); 282 data = filp->private_data; 283 284 switch (cmd) { 285 286 case SNAPSHOT_FREEZE: 287 if (data->frozen) 288 break; 289 290 error = pm_sleep_fs_sync(); 291 if (error) 292 break; 293 294 error = freeze_processes(); 295 if (error) 296 break; 297 298 error = create_basic_memory_bitmaps(); 299 if (error) 300 thaw_processes(); 301 else 302 data->frozen = true; 303 304 break; 305 306 case SNAPSHOT_UNFREEZE: 307 if (!data->frozen || data->ready) 308 break; 309 pm_restore_gfp_mask(); 310 free_basic_memory_bitmaps(); 311 data->free_bitmaps = false; 312 thaw_processes(); 313 data->frozen = false; 314 break; 315 316 case SNAPSHOT_CREATE_IMAGE: 317 if (data->mode != O_RDONLY || !data->frozen || data->ready) { 318 error = -EPERM; 319 break; 320 } 321 pm_restore_gfp_mask(); 322 error = hibernation_snapshot(data->platform_support); 323 if (!error) { 324 error = put_user(in_suspend, (int __user *)arg); 325 data->ready = !freezer_test_done && !error; 326 freezer_test_done = false; 327 } 328 break; 329 330 case SNAPSHOT_ATOMIC_RESTORE: 331 error = snapshot_write_finalize(&data->handle); 332 if (error) 333 break; 334 if (data->mode != O_WRONLY || !data->frozen) { 335 error = -EPERM; 336 break; 337 } 338 if (!snapshot_image_loaded(&data->handle)) { 339 error = -ENODATA; 340 break; 341 } 342 error = hibernation_restore(data->platform_support); 343 break; 344 345 case SNAPSHOT_FREE: 346 swsusp_free(); 347 memset(&data->handle, 0, sizeof(struct snapshot_handle)); 348 data->ready = false; 349 /* 350 * It is necessary to thaw kernel threads here, because 351 * SNAPSHOT_CREATE_IMAGE may be invoked directly after 352 * SNAPSHOT_FREE. In that case, if kernel threads were not 353 * thawed, the preallocation of memory carried out by 354 * hibernation_snapshot() might run into problems (i.e. it 355 * might fail or even deadlock). 356 */ 357 thaw_kernel_threads(); 358 break; 359 360 case SNAPSHOT_PREF_IMAGE_SIZE: 361 image_size = arg; 362 break; 363 364 case SNAPSHOT_GET_IMAGE_SIZE: 365 if (!data->ready) { 366 error = -ENODATA; 367 break; 368 } 369 size = snapshot_get_image_size(); 370 size <<= PAGE_SHIFT; 371 error = put_user(size, (loff_t __user *)arg); 372 break; 373 374 case SNAPSHOT_AVAIL_SWAP_SIZE: 375 size = count_swap_pages(data->swap, 1); 376 size <<= PAGE_SHIFT; 377 error = put_user(size, (loff_t __user *)arg); 378 break; 379 380 case SNAPSHOT_ALLOC_SWAP_PAGE: 381 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) { 382 error = -ENODEV; 383 break; 384 } 385 offset = alloc_swapdev_block(data->swap); 386 if (offset) { 387 offset <<= PAGE_SHIFT; 388 error = put_user(offset, (loff_t __user *)arg); 389 } else { 390 error = -ENOSPC; 391 } 392 break; 393 394 case SNAPSHOT_FREE_SWAP_PAGES: 395 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) { 396 error = -ENODEV; 397 break; 398 } 399 free_all_swap_pages(data->swap); 400 break; 401 402 case SNAPSHOT_S2RAM: 403 if (!data->frozen) { 404 error = -EPERM; 405 break; 406 } 407 /* 408 * Tasks are frozen and the notifiers have been called with 409 * PM_HIBERNATION_PREPARE 410 */ 411 error = suspend_devices_and_enter(PM_SUSPEND_MEM); 412 data->ready = false; 413 break; 414 415 case SNAPSHOT_PLATFORM_SUPPORT: 416 data->platform_support = !!arg; 417 break; 418 419 case SNAPSHOT_POWER_OFF: 420 if (data->platform_support) 421 error = hibernation_platform_enter(); 422 break; 423 424 case SNAPSHOT_SET_SWAP_AREA: 425 error = snapshot_set_swap_area(data, (void __user *)arg); 426 break; 427 428 default: 429 error = -ENOTTY; 430 431 } 432 433 unlock_device_hotplug(); 434 mutex_unlock(&system_transition_mutex); 435 436 return error; 437 } 438 439 #ifdef CONFIG_COMPAT 440 static long 441 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 442 { 443 BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t)); 444 445 switch (cmd) { 446 case SNAPSHOT_GET_IMAGE_SIZE: 447 case SNAPSHOT_AVAIL_SWAP_SIZE: 448 case SNAPSHOT_ALLOC_SWAP_PAGE: 449 case SNAPSHOT_CREATE_IMAGE: 450 case SNAPSHOT_SET_SWAP_AREA: 451 return snapshot_ioctl(file, cmd, 452 (unsigned long) compat_ptr(arg)); 453 default: 454 return snapshot_ioctl(file, cmd, arg); 455 } 456 } 457 #endif /* CONFIG_COMPAT */ 458 459 static const struct file_operations snapshot_fops = { 460 .open = snapshot_open, 461 .release = snapshot_release, 462 .read = snapshot_read, 463 .write = snapshot_write, 464 .unlocked_ioctl = snapshot_ioctl, 465 #ifdef CONFIG_COMPAT 466 .compat_ioctl = snapshot_compat_ioctl, 467 #endif 468 }; 469 470 static struct miscdevice snapshot_device = { 471 .minor = SNAPSHOT_MINOR, 472 .name = "snapshot", 473 .fops = &snapshot_fops, 474 }; 475 476 static int __init snapshot_device_init(void) 477 { 478 return misc_register(&snapshot_device); 479 }; 480 481 device_initcall(snapshot_device_init); 482