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