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 
is_hibernate_resume_dev(dev_t dev)42 int is_hibernate_resume_dev(dev_t dev)
43 {
44 	return hibernation_available() && snapshot_state.dev == dev;
45 }
46 
snapshot_open(struct inode * inode,struct file * filp)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 
snapshot_release(struct inode * inode,struct file * filp)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 
snapshot_read(struct file * filp,char __user * buf,size_t count,loff_t * offp)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 
snapshot_write(struct file * filp,const char __user * buf,size_t count,loff_t * offp)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 
snapshot_set_swap_area(struct snapshot_data * data,void __user * argp)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 
snapshot_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)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 		snapshot_write_finalize(&data->handle);
321 		if (data->mode != O_WRONLY || !data->frozen ||
322 		    !snapshot_image_loaded(&data->handle)) {
323 			error = -EPERM;
324 			break;
325 		}
326 		error = hibernation_restore(data->platform_support);
327 		break;
328 
329 	case SNAPSHOT_FREE:
330 		swsusp_free();
331 		memset(&data->handle, 0, sizeof(struct snapshot_handle));
332 		data->ready = false;
333 		/*
334 		 * It is necessary to thaw kernel threads here, because
335 		 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
336 		 * SNAPSHOT_FREE.  In that case, if kernel threads were not
337 		 * thawed, the preallocation of memory carried out by
338 		 * hibernation_snapshot() might run into problems (i.e. it
339 		 * might fail or even deadlock).
340 		 */
341 		thaw_kernel_threads();
342 		break;
343 
344 	case SNAPSHOT_PREF_IMAGE_SIZE:
345 		image_size = arg;
346 		break;
347 
348 	case SNAPSHOT_GET_IMAGE_SIZE:
349 		if (!data->ready) {
350 			error = -ENODATA;
351 			break;
352 		}
353 		size = snapshot_get_image_size();
354 		size <<= PAGE_SHIFT;
355 		error = put_user(size, (loff_t __user *)arg);
356 		break;
357 
358 	case SNAPSHOT_AVAIL_SWAP_SIZE:
359 		size = count_swap_pages(data->swap, 1);
360 		size <<= PAGE_SHIFT;
361 		error = put_user(size, (loff_t __user *)arg);
362 		break;
363 
364 	case SNAPSHOT_ALLOC_SWAP_PAGE:
365 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
366 			error = -ENODEV;
367 			break;
368 		}
369 		offset = alloc_swapdev_block(data->swap);
370 		if (offset) {
371 			offset <<= PAGE_SHIFT;
372 			error = put_user(offset, (loff_t __user *)arg);
373 		} else {
374 			error = -ENOSPC;
375 		}
376 		break;
377 
378 	case SNAPSHOT_FREE_SWAP_PAGES:
379 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
380 			error = -ENODEV;
381 			break;
382 		}
383 		free_all_swap_pages(data->swap);
384 		break;
385 
386 	case SNAPSHOT_S2RAM:
387 		if (!data->frozen) {
388 			error = -EPERM;
389 			break;
390 		}
391 		/*
392 		 * Tasks are frozen and the notifiers have been called with
393 		 * PM_HIBERNATION_PREPARE
394 		 */
395 		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
396 		data->ready = false;
397 		break;
398 
399 	case SNAPSHOT_PLATFORM_SUPPORT:
400 		data->platform_support = !!arg;
401 		break;
402 
403 	case SNAPSHOT_POWER_OFF:
404 		if (data->platform_support)
405 			error = hibernation_platform_enter();
406 		break;
407 
408 	case SNAPSHOT_SET_SWAP_AREA:
409 		error = snapshot_set_swap_area(data, (void __user *)arg);
410 		break;
411 
412 	default:
413 		error = -ENOTTY;
414 
415 	}
416 
417 	unlock_device_hotplug();
418 	mutex_unlock(&system_transition_mutex);
419 
420 	return error;
421 }
422 
423 #ifdef CONFIG_COMPAT
424 static long
snapshot_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)425 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
426 {
427 	BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
428 
429 	switch (cmd) {
430 	case SNAPSHOT_GET_IMAGE_SIZE:
431 	case SNAPSHOT_AVAIL_SWAP_SIZE:
432 	case SNAPSHOT_ALLOC_SWAP_PAGE:
433 	case SNAPSHOT_CREATE_IMAGE:
434 	case SNAPSHOT_SET_SWAP_AREA:
435 		return snapshot_ioctl(file, cmd,
436 				      (unsigned long) compat_ptr(arg));
437 	default:
438 		return snapshot_ioctl(file, cmd, arg);
439 	}
440 }
441 #endif /* CONFIG_COMPAT */
442 
443 static const struct file_operations snapshot_fops = {
444 	.open = snapshot_open,
445 	.release = snapshot_release,
446 	.read = snapshot_read,
447 	.write = snapshot_write,
448 	.llseek = no_llseek,
449 	.unlocked_ioctl = snapshot_ioctl,
450 #ifdef CONFIG_COMPAT
451 	.compat_ioctl = snapshot_compat_ioctl,
452 #endif
453 };
454 
455 static struct miscdevice snapshot_device = {
456 	.minor = SNAPSHOT_MINOR,
457 	.name = "snapshot",
458 	.fops = &snapshot_fops,
459 };
460 
snapshot_device_init(void)461 static int __init snapshot_device_init(void)
462 {
463 	return misc_register(&snapshot_device);
464 };
465 
466 device_initcall(snapshot_device_init);
467