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 #define SNAPSHOT_MINOR 231 31 32 static struct snapshot_data { 33 struct snapshot_handle handle; 34 int swap; 35 int mode; 36 bool frozen; 37 bool ready; 38 bool platform_support; 39 bool free_bitmaps; 40 } snapshot_state; 41 42 atomic_t snapshot_device_available = ATOMIC_INIT(1); 43 44 static int snapshot_open(struct inode *inode, struct file *filp) 45 { 46 struct snapshot_data *data; 47 int error, nr_calls = 0; 48 49 if (!hibernation_available()) 50 return -EPERM; 51 52 lock_system_sleep(); 53 54 if (!atomic_add_unless(&snapshot_device_available, -1, 0)) { 55 error = -EBUSY; 56 goto Unlock; 57 } 58 59 if ((filp->f_flags & O_ACCMODE) == O_RDWR) { 60 atomic_inc(&snapshot_device_available); 61 error = -ENOSYS; 62 goto Unlock; 63 } 64 nonseekable_open(inode, filp); 65 data = &snapshot_state; 66 filp->private_data = data; 67 memset(&data->handle, 0, sizeof(struct snapshot_handle)); 68 if ((filp->f_flags & O_ACCMODE) == O_RDONLY) { 69 /* Hibernating. The image device should be accessible. */ 70 data->swap = swsusp_resume_device ? 71 swap_type_of(swsusp_resume_device, 0, NULL) : -1; 72 data->mode = O_RDONLY; 73 data->free_bitmaps = false; 74 error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls); 75 if (error) 76 __pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL); 77 } else { 78 /* 79 * Resuming. We may need to wait for the image device to 80 * appear. 81 */ 82 wait_for_device_probe(); 83 84 data->swap = -1; 85 data->mode = O_WRONLY; 86 error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls); 87 if (!error) { 88 error = create_basic_memory_bitmaps(); 89 data->free_bitmaps = !error; 90 } else 91 nr_calls--; 92 93 if (error) 94 __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL); 95 } 96 if (error) 97 atomic_inc(&snapshot_device_available); 98 99 data->frozen = false; 100 data->ready = false; 101 data->platform_support = false; 102 103 Unlock: 104 unlock_system_sleep(); 105 106 return error; 107 } 108 109 static int snapshot_release(struct inode *inode, struct file *filp) 110 { 111 struct snapshot_data *data; 112 113 lock_system_sleep(); 114 115 swsusp_free(); 116 data = filp->private_data; 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 atomic_inc(&snapshot_device_available); 128 129 unlock_system_sleep(); 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 struct snapshot_data *data; 138 ssize_t res; 139 loff_t pg_offp = *offp & ~PAGE_MASK; 140 141 lock_system_sleep(); 142 143 data = filp->private_data; 144 if (!data->ready) { 145 res = -ENODATA; 146 goto Unlock; 147 } 148 if (!pg_offp) { /* on page boundary? */ 149 res = snapshot_read_next(&data->handle); 150 if (res <= 0) 151 goto Unlock; 152 } else { 153 res = PAGE_SIZE - pg_offp; 154 } 155 156 res = simple_read_from_buffer(buf, count, &pg_offp, 157 data_of(data->handle), res); 158 if (res > 0) 159 *offp += res; 160 161 Unlock: 162 unlock_system_sleep(); 163 164 return res; 165 } 166 167 static ssize_t snapshot_write(struct file *filp, const char __user *buf, 168 size_t count, loff_t *offp) 169 { 170 struct snapshot_data *data; 171 ssize_t res; 172 loff_t pg_offp = *offp & ~PAGE_MASK; 173 174 lock_system_sleep(); 175 176 data = filp->private_data; 177 178 if (!pg_offp) { 179 res = snapshot_write_next(&data->handle); 180 if (res <= 0) 181 goto unlock; 182 } else { 183 res = PAGE_SIZE - pg_offp; 184 } 185 186 if (!data_of(data->handle)) { 187 res = -EINVAL; 188 goto unlock; 189 } 190 191 res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp, 192 buf, count); 193 if (res > 0) 194 *offp += res; 195 unlock: 196 unlock_system_sleep(); 197 198 return res; 199 } 200 201 static long snapshot_ioctl(struct file *filp, unsigned int cmd, 202 unsigned long arg) 203 { 204 int error = 0; 205 struct snapshot_data *data; 206 loff_t size; 207 sector_t offset; 208 209 if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC) 210 return -ENOTTY; 211 if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR) 212 return -ENOTTY; 213 if (!capable(CAP_SYS_ADMIN)) 214 return -EPERM; 215 216 if (!mutex_trylock(&system_transition_mutex)) 217 return -EBUSY; 218 219 lock_device_hotplug(); 220 data = filp->private_data; 221 222 switch (cmd) { 223 224 case SNAPSHOT_FREEZE: 225 if (data->frozen) 226 break; 227 228 ksys_sync_helper(); 229 230 error = freeze_processes(); 231 if (error) 232 break; 233 234 error = create_basic_memory_bitmaps(); 235 if (error) 236 thaw_processes(); 237 else 238 data->frozen = true; 239 240 break; 241 242 case SNAPSHOT_UNFREEZE: 243 if (!data->frozen || data->ready) 244 break; 245 pm_restore_gfp_mask(); 246 free_basic_memory_bitmaps(); 247 data->free_bitmaps = false; 248 thaw_processes(); 249 data->frozen = false; 250 break; 251 252 case SNAPSHOT_CREATE_IMAGE: 253 if (data->mode != O_RDONLY || !data->frozen || data->ready) { 254 error = -EPERM; 255 break; 256 } 257 pm_restore_gfp_mask(); 258 error = hibernation_snapshot(data->platform_support); 259 if (!error) { 260 error = put_user(in_suspend, (int __user *)arg); 261 data->ready = !freezer_test_done && !error; 262 freezer_test_done = false; 263 } 264 break; 265 266 case SNAPSHOT_ATOMIC_RESTORE: 267 snapshot_write_finalize(&data->handle); 268 if (data->mode != O_WRONLY || !data->frozen || 269 !snapshot_image_loaded(&data->handle)) { 270 error = -EPERM; 271 break; 272 } 273 error = hibernation_restore(data->platform_support); 274 break; 275 276 case SNAPSHOT_FREE: 277 swsusp_free(); 278 memset(&data->handle, 0, sizeof(struct snapshot_handle)); 279 data->ready = false; 280 /* 281 * It is necessary to thaw kernel threads here, because 282 * SNAPSHOT_CREATE_IMAGE may be invoked directly after 283 * SNAPSHOT_FREE. In that case, if kernel threads were not 284 * thawed, the preallocation of memory carried out by 285 * hibernation_snapshot() might run into problems (i.e. it 286 * might fail or even deadlock). 287 */ 288 thaw_kernel_threads(); 289 break; 290 291 case SNAPSHOT_PREF_IMAGE_SIZE: 292 image_size = arg; 293 break; 294 295 case SNAPSHOT_GET_IMAGE_SIZE: 296 if (!data->ready) { 297 error = -ENODATA; 298 break; 299 } 300 size = snapshot_get_image_size(); 301 size <<= PAGE_SHIFT; 302 error = put_user(size, (loff_t __user *)arg); 303 break; 304 305 case SNAPSHOT_AVAIL_SWAP_SIZE: 306 size = count_swap_pages(data->swap, 1); 307 size <<= PAGE_SHIFT; 308 error = put_user(size, (loff_t __user *)arg); 309 break; 310 311 case SNAPSHOT_ALLOC_SWAP_PAGE: 312 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) { 313 error = -ENODEV; 314 break; 315 } 316 offset = alloc_swapdev_block(data->swap); 317 if (offset) { 318 offset <<= PAGE_SHIFT; 319 error = put_user(offset, (loff_t __user *)arg); 320 } else { 321 error = -ENOSPC; 322 } 323 break; 324 325 case SNAPSHOT_FREE_SWAP_PAGES: 326 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) { 327 error = -ENODEV; 328 break; 329 } 330 free_all_swap_pages(data->swap); 331 break; 332 333 case SNAPSHOT_S2RAM: 334 if (!data->frozen) { 335 error = -EPERM; 336 break; 337 } 338 /* 339 * Tasks are frozen and the notifiers have been called with 340 * PM_HIBERNATION_PREPARE 341 */ 342 error = suspend_devices_and_enter(PM_SUSPEND_MEM); 343 data->ready = false; 344 break; 345 346 case SNAPSHOT_PLATFORM_SUPPORT: 347 data->platform_support = !!arg; 348 break; 349 350 case SNAPSHOT_POWER_OFF: 351 if (data->platform_support) 352 error = hibernation_platform_enter(); 353 break; 354 355 case SNAPSHOT_SET_SWAP_AREA: 356 if (swsusp_swap_in_use()) { 357 error = -EPERM; 358 } else { 359 struct resume_swap_area swap_area; 360 dev_t swdev; 361 362 error = copy_from_user(&swap_area, (void __user *)arg, 363 sizeof(struct resume_swap_area)); 364 if (error) { 365 error = -EFAULT; 366 break; 367 } 368 369 /* 370 * User space encodes device types as two-byte values, 371 * so we need to recode them 372 */ 373 swdev = new_decode_dev(swap_area.dev); 374 if (swdev) { 375 offset = swap_area.offset; 376 data->swap = swap_type_of(swdev, offset, NULL); 377 if (data->swap < 0) 378 error = -ENODEV; 379 } else { 380 data->swap = -1; 381 error = -EINVAL; 382 } 383 } 384 break; 385 386 default: 387 error = -ENOTTY; 388 389 } 390 391 unlock_device_hotplug(); 392 mutex_unlock(&system_transition_mutex); 393 394 return error; 395 } 396 397 #ifdef CONFIG_COMPAT 398 399 struct compat_resume_swap_area { 400 compat_loff_t offset; 401 u32 dev; 402 } __packed; 403 404 static long 405 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 406 { 407 BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t)); 408 409 switch (cmd) { 410 case SNAPSHOT_GET_IMAGE_SIZE: 411 case SNAPSHOT_AVAIL_SWAP_SIZE: 412 case SNAPSHOT_ALLOC_SWAP_PAGE: { 413 compat_loff_t __user *uoffset = compat_ptr(arg); 414 loff_t offset; 415 mm_segment_t old_fs; 416 int err; 417 418 old_fs = get_fs(); 419 set_fs(KERNEL_DS); 420 err = snapshot_ioctl(file, cmd, (unsigned long) &offset); 421 set_fs(old_fs); 422 if (!err && put_user(offset, uoffset)) 423 err = -EFAULT; 424 return err; 425 } 426 427 case SNAPSHOT_CREATE_IMAGE: 428 return snapshot_ioctl(file, cmd, 429 (unsigned long) compat_ptr(arg)); 430 431 case SNAPSHOT_SET_SWAP_AREA: { 432 struct compat_resume_swap_area __user *u_swap_area = 433 compat_ptr(arg); 434 struct resume_swap_area swap_area; 435 mm_segment_t old_fs; 436 int err; 437 438 err = get_user(swap_area.offset, &u_swap_area->offset); 439 err |= get_user(swap_area.dev, &u_swap_area->dev); 440 if (err) 441 return -EFAULT; 442 old_fs = get_fs(); 443 set_fs(KERNEL_DS); 444 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA, 445 (unsigned long) &swap_area); 446 set_fs(old_fs); 447 return err; 448 } 449 450 default: 451 return snapshot_ioctl(file, cmd, arg); 452 } 453 } 454 455 #endif /* CONFIG_COMPAT */ 456 457 static const struct file_operations snapshot_fops = { 458 .open = snapshot_open, 459 .release = snapshot_release, 460 .read = snapshot_read, 461 .write = snapshot_write, 462 .llseek = no_llseek, 463 .unlocked_ioctl = snapshot_ioctl, 464 #ifdef CONFIG_COMPAT 465 .compat_ioctl = snapshot_compat_ioctl, 466 #endif 467 }; 468 469 static struct miscdevice snapshot_device = { 470 .minor = SNAPSHOT_MINOR, 471 .name = "snapshot", 472 .fops = &snapshot_fops, 473 }; 474 475 static int __init snapshot_device_init(void) 476 { 477 return misc_register(&snapshot_device); 478 }; 479 480 device_initcall(snapshot_device_init); 481