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; 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); 463