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 = swap_type_of(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 hibernate_release(); 95 96 data->frozen = false; 97 data->ready = false; 98 data->platform_support = false; 99 data->dev = 0; 100 101 Unlock: 102 unlock_system_sleep(sleep_flags); 103 104 return error; 105 } 106 107 static int snapshot_release(struct inode *inode, struct file *filp) 108 { 109 struct snapshot_data *data; 110 unsigned int sleep_flags; 111 112 sleep_flags = lock_system_sleep(); 113 114 swsusp_free(); 115 data = filp->private_data; 116 data->dev = 0; 117 free_all_swap_pages(data->swap); 118 if (data->frozen) { 119 pm_restore_gfp_mask(); 120 free_basic_memory_bitmaps(); 121 thaw_processes(); 122 } else if (data->free_bitmaps) { 123 free_basic_memory_bitmaps(); 124 } 125 pm_notifier_call_chain(data->mode == O_RDONLY ? 126 PM_POST_HIBERNATION : PM_POST_RESTORE); 127 hibernate_release(); 128 129 unlock_system_sleep(sleep_flags); 130 131 return 0; 132 } 133 134 static ssize_t snapshot_read(struct file *filp, char __user *buf, 135 size_t count, loff_t *offp) 136 { 137 loff_t pg_offp = *offp & ~PAGE_MASK; 138 struct snapshot_data *data; 139 unsigned int sleep_flags; 140 ssize_t res; 141 142 sleep_flags = lock_system_sleep(); 143 144 data = filp->private_data; 145 if (!data->ready) { 146 res = -ENODATA; 147 goto Unlock; 148 } 149 if (!pg_offp) { /* on page boundary? */ 150 res = snapshot_read_next(&data->handle); 151 if (res <= 0) 152 goto Unlock; 153 } else { 154 res = PAGE_SIZE - pg_offp; 155 } 156 157 res = simple_read_from_buffer(buf, count, &pg_offp, 158 data_of(data->handle), res); 159 if (res > 0) 160 *offp += res; 161 162 Unlock: 163 unlock_system_sleep(sleep_flags); 164 165 return res; 166 } 167 168 static ssize_t snapshot_write(struct file *filp, const char __user *buf, 169 size_t count, loff_t *offp) 170 { 171 loff_t pg_offp = *offp & ~PAGE_MASK; 172 struct snapshot_data *data; 173 unsigned long sleep_flags; 174 ssize_t res; 175 176 if (need_wait) { 177 wait_for_device_probe(); 178 need_wait = false; 179 } 180 181 sleep_flags = lock_system_sleep(); 182 183 data = filp->private_data; 184 185 if (!pg_offp) { 186 res = snapshot_write_next(&data->handle); 187 if (res <= 0) 188 goto unlock; 189 } else { 190 res = PAGE_SIZE; 191 } 192 193 if (!data_of(data->handle)) { 194 res = -EINVAL; 195 goto unlock; 196 } 197 198 res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp, 199 buf, count); 200 if (res > 0) 201 *offp += res; 202 unlock: 203 unlock_system_sleep(sleep_flags); 204 205 return res; 206 } 207 208 struct compat_resume_swap_area { 209 compat_loff_t offset; 210 u32 dev; 211 } __packed; 212 213 static int snapshot_set_swap_area(struct snapshot_data *data, 214 void __user *argp) 215 { 216 sector_t offset; 217 dev_t swdev; 218 219 if (swsusp_swap_in_use()) 220 return -EPERM; 221 222 if (in_compat_syscall()) { 223 struct compat_resume_swap_area swap_area; 224 225 if (copy_from_user(&swap_area, argp, sizeof(swap_area))) 226 return -EFAULT; 227 swdev = new_decode_dev(swap_area.dev); 228 offset = swap_area.offset; 229 } else { 230 struct resume_swap_area swap_area; 231 232 if (copy_from_user(&swap_area, argp, sizeof(swap_area))) 233 return -EFAULT; 234 swdev = new_decode_dev(swap_area.dev); 235 offset = swap_area.offset; 236 } 237 238 /* 239 * User space encodes device types as two-byte values, 240 * so we need to recode them 241 */ 242 data->swap = swap_type_of(swdev, offset); 243 if (data->swap < 0) 244 return swdev ? -ENODEV : -EINVAL; 245 data->dev = swdev; 246 return 0; 247 } 248 249 static long snapshot_ioctl(struct file *filp, unsigned int cmd, 250 unsigned long arg) 251 { 252 int error = 0; 253 struct snapshot_data *data; 254 loff_t size; 255 sector_t offset; 256 257 if (need_wait) { 258 wait_for_device_probe(); 259 need_wait = false; 260 } 261 262 if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC) 263 return -ENOTTY; 264 if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR) 265 return -ENOTTY; 266 if (!capable(CAP_SYS_ADMIN)) 267 return -EPERM; 268 269 if (!mutex_trylock(&system_transition_mutex)) 270 return -EBUSY; 271 272 lock_device_hotplug(); 273 data = filp->private_data; 274 275 switch (cmd) { 276 277 case SNAPSHOT_FREEZE: 278 if (data->frozen) 279 break; 280 281 ksys_sync_helper(); 282 283 error = freeze_processes(); 284 if (error) 285 break; 286 287 error = create_basic_memory_bitmaps(); 288 if (error) 289 thaw_processes(); 290 else 291 data->frozen = true; 292 293 break; 294 295 case SNAPSHOT_UNFREEZE: 296 if (!data->frozen || data->ready) 297 break; 298 pm_restore_gfp_mask(); 299 free_basic_memory_bitmaps(); 300 data->free_bitmaps = false; 301 thaw_processes(); 302 data->frozen = false; 303 break; 304 305 case SNAPSHOT_CREATE_IMAGE: 306 if (data->mode != O_RDONLY || !data->frozen || data->ready) { 307 error = -EPERM; 308 break; 309 } 310 pm_restore_gfp_mask(); 311 error = hibernation_snapshot(data->platform_support); 312 if (!error) { 313 error = put_user(in_suspend, (int __user *)arg); 314 data->ready = !freezer_test_done && !error; 315 freezer_test_done = false; 316 } 317 break; 318 319 case SNAPSHOT_ATOMIC_RESTORE: 320 error = snapshot_write_finalize(&data->handle); 321 if (error) 322 break; 323 if (data->mode != O_WRONLY || !data->frozen || 324 !snapshot_image_loaded(&data->handle)) { 325 error = -EPERM; 326 break; 327 } 328 error = hibernation_restore(data->platform_support); 329 break; 330 331 case SNAPSHOT_FREE: 332 swsusp_free(); 333 memset(&data->handle, 0, sizeof(struct snapshot_handle)); 334 data->ready = false; 335 /* 336 * It is necessary to thaw kernel threads here, because 337 * SNAPSHOT_CREATE_IMAGE may be invoked directly after 338 * SNAPSHOT_FREE. In that case, if kernel threads were not 339 * thawed, the preallocation of memory carried out by 340 * hibernation_snapshot() might run into problems (i.e. it 341 * might fail or even deadlock). 342 */ 343 thaw_kernel_threads(); 344 break; 345 346 case SNAPSHOT_PREF_IMAGE_SIZE: 347 image_size = arg; 348 break; 349 350 case SNAPSHOT_GET_IMAGE_SIZE: 351 if (!data->ready) { 352 error = -ENODATA; 353 break; 354 } 355 size = snapshot_get_image_size(); 356 size <<= PAGE_SHIFT; 357 error = put_user(size, (loff_t __user *)arg); 358 break; 359 360 case SNAPSHOT_AVAIL_SWAP_SIZE: 361 size = count_swap_pages(data->swap, 1); 362 size <<= PAGE_SHIFT; 363 error = put_user(size, (loff_t __user *)arg); 364 break; 365 366 case SNAPSHOT_ALLOC_SWAP_PAGE: 367 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) { 368 error = -ENODEV; 369 break; 370 } 371 offset = alloc_swapdev_block(data->swap); 372 if (offset) { 373 offset <<= PAGE_SHIFT; 374 error = put_user(offset, (loff_t __user *)arg); 375 } else { 376 error = -ENOSPC; 377 } 378 break; 379 380 case SNAPSHOT_FREE_SWAP_PAGES: 381 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) { 382 error = -ENODEV; 383 break; 384 } 385 free_all_swap_pages(data->swap); 386 break; 387 388 case SNAPSHOT_S2RAM: 389 if (!data->frozen) { 390 error = -EPERM; 391 break; 392 } 393 /* 394 * Tasks are frozen and the notifiers have been called with 395 * PM_HIBERNATION_PREPARE 396 */ 397 error = suspend_devices_and_enter(PM_SUSPEND_MEM); 398 data->ready = false; 399 break; 400 401 case SNAPSHOT_PLATFORM_SUPPORT: 402 data->platform_support = !!arg; 403 break; 404 405 case SNAPSHOT_POWER_OFF: 406 if (data->platform_support) 407 error = hibernation_platform_enter(); 408 break; 409 410 case SNAPSHOT_SET_SWAP_AREA: 411 error = snapshot_set_swap_area(data, (void __user *)arg); 412 break; 413 414 default: 415 error = -ENOTTY; 416 417 } 418 419 unlock_device_hotplug(); 420 mutex_unlock(&system_transition_mutex); 421 422 return error; 423 } 424 425 #ifdef CONFIG_COMPAT 426 static long 427 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 428 { 429 BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t)); 430 431 switch (cmd) { 432 case SNAPSHOT_GET_IMAGE_SIZE: 433 case SNAPSHOT_AVAIL_SWAP_SIZE: 434 case SNAPSHOT_ALLOC_SWAP_PAGE: 435 case SNAPSHOT_CREATE_IMAGE: 436 case SNAPSHOT_SET_SWAP_AREA: 437 return snapshot_ioctl(file, cmd, 438 (unsigned long) compat_ptr(arg)); 439 default: 440 return snapshot_ioctl(file, cmd, arg); 441 } 442 } 443 #endif /* CONFIG_COMPAT */ 444 445 static const struct file_operations snapshot_fops = { 446 .open = snapshot_open, 447 .release = snapshot_release, 448 .read = snapshot_read, 449 .write = snapshot_write, 450 .llseek = no_llseek, 451 .unlocked_ioctl = snapshot_ioctl, 452 #ifdef CONFIG_COMPAT 453 .compat_ioctl = snapshot_compat_ioctl, 454 #endif 455 }; 456 457 static struct miscdevice snapshot_device = { 458 .minor = SNAPSHOT_MINOR, 459 .name = "snapshot", 460 .fops = &snapshot_fops, 461 }; 462 463 static int __init snapshot_device_init(void) 464 { 465 return misc_register(&snapshot_device); 466 }; 467 468 device_initcall(snapshot_device_init); 469