xref: /linux-6.15/kernel/power/user.c (revision c8ea0d67) 
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 <[email protected]>
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 	struct inode *bd_inode;
39 } snapshot_state;
40 
41 int is_hibernate_resume_dev(const struct inode *bd_inode)
42 {
43 	return hibernation_available() && snapshot_state.bd_inode == bd_inode;
44 }
45 
46 static int snapshot_open(struct inode *inode, struct file *filp)
47 {
48 	struct snapshot_data *data;
49 	int error;
50 
51 	if (!hibernation_available())
52 		return -EPERM;
53 
54 	lock_system_sleep();
55 
56 	if (!hibernate_acquire()) {
57 		error = -EBUSY;
58 		goto Unlock;
59 	}
60 
61 	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
62 		hibernate_release();
63 		error = -ENOSYS;
64 		goto Unlock;
65 	}
66 	nonseekable_open(inode, filp);
67 	data = &snapshot_state;
68 	filp->private_data = data;
69 	memset(&data->handle, 0, sizeof(struct snapshot_handle));
70 	if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
71 		/* Hibernating.  The image device should be accessible. */
72 		data->swap = swsusp_resume_device ?
73 			swap_type_of(swsusp_resume_device, 0, NULL) : -1;
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 		wait_for_device_probe();
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->bd_inode = NULL;
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->bd_inode = NULL;
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 	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 	struct block_device *bdev;
208 	sector_t offset;
209 	dev_t swdev;
210 
211 	if (swsusp_swap_in_use())
212 		return -EPERM;
213 
214 	if (in_compat_syscall()) {
215 		struct compat_resume_swap_area swap_area;
216 
217 		if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
218 			return -EFAULT;
219 		swdev = new_decode_dev(swap_area.dev);
220 		offset = swap_area.offset;
221 	} else {
222 		struct resume_swap_area swap_area;
223 
224 		if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
225 			return -EFAULT;
226 		swdev = new_decode_dev(swap_area.dev);
227 		offset = swap_area.offset;
228 	}
229 
230 	/*
231 	 * User space encodes device types as two-byte values,
232 	 * so we need to recode them
233 	 */
234 	if (!swdev) {
235 		data->swap = -1;
236 		return -EINVAL;
237 	}
238 	data->swap = swap_type_of(swdev, offset, &bdev);
239 	if (data->swap < 0)
240 		return -ENODEV;
241 
242 	data->bd_inode = bdev->bd_inode;
243 	bdput(bdev);
244 	return 0;
245 }
246 
247 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
248 							unsigned long arg)
249 {
250 	int error = 0;
251 	struct snapshot_data *data;
252 	loff_t size;
253 	sector_t offset;
254 
255 	if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
256 		return -ENOTTY;
257 	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
258 		return -ENOTTY;
259 	if (!capable(CAP_SYS_ADMIN))
260 		return -EPERM;
261 
262 	if (!mutex_trylock(&system_transition_mutex))
263 		return -EBUSY;
264 
265 	lock_device_hotplug();
266 	data = filp->private_data;
267 
268 	switch (cmd) {
269 
270 	case SNAPSHOT_FREEZE:
271 		if (data->frozen)
272 			break;
273 
274 		ksys_sync_helper();
275 
276 		error = freeze_processes();
277 		if (error)
278 			break;
279 
280 		error = create_basic_memory_bitmaps();
281 		if (error)
282 			thaw_processes();
283 		else
284 			data->frozen = true;
285 
286 		break;
287 
288 	case SNAPSHOT_UNFREEZE:
289 		if (!data->frozen || data->ready)
290 			break;
291 		pm_restore_gfp_mask();
292 		free_basic_memory_bitmaps();
293 		data->free_bitmaps = false;
294 		thaw_processes();
295 		data->frozen = false;
296 		break;
297 
298 	case SNAPSHOT_CREATE_IMAGE:
299 		if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
300 			error = -EPERM;
301 			break;
302 		}
303 		pm_restore_gfp_mask();
304 		error = hibernation_snapshot(data->platform_support);
305 		if (!error) {
306 			error = put_user(in_suspend, (int __user *)arg);
307 			data->ready = !freezer_test_done && !error;
308 			freezer_test_done = false;
309 		}
310 		break;
311 
312 	case SNAPSHOT_ATOMIC_RESTORE:
313 		snapshot_write_finalize(&data->handle);
314 		if (data->mode != O_WRONLY || !data->frozen ||
315 		    !snapshot_image_loaded(&data->handle)) {
316 			error = -EPERM;
317 			break;
318 		}
319 		error = hibernation_restore(data->platform_support);
320 		break;
321 
322 	case SNAPSHOT_FREE:
323 		swsusp_free();
324 		memset(&data->handle, 0, sizeof(struct snapshot_handle));
325 		data->ready = false;
326 		/*
327 		 * It is necessary to thaw kernel threads here, because
328 		 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
329 		 * SNAPSHOT_FREE.  In that case, if kernel threads were not
330 		 * thawed, the preallocation of memory carried out by
331 		 * hibernation_snapshot() might run into problems (i.e. it
332 		 * might fail or even deadlock).
333 		 */
334 		thaw_kernel_threads();
335 		break;
336 
337 	case SNAPSHOT_PREF_IMAGE_SIZE:
338 		image_size = arg;
339 		break;
340 
341 	case SNAPSHOT_GET_IMAGE_SIZE:
342 		if (!data->ready) {
343 			error = -ENODATA;
344 			break;
345 		}
346 		size = snapshot_get_image_size();
347 		size <<= PAGE_SHIFT;
348 		error = put_user(size, (loff_t __user *)arg);
349 		break;
350 
351 	case SNAPSHOT_AVAIL_SWAP_SIZE:
352 		size = count_swap_pages(data->swap, 1);
353 		size <<= PAGE_SHIFT;
354 		error = put_user(size, (loff_t __user *)arg);
355 		break;
356 
357 	case SNAPSHOT_ALLOC_SWAP_PAGE:
358 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
359 			error = -ENODEV;
360 			break;
361 		}
362 		offset = alloc_swapdev_block(data->swap);
363 		if (offset) {
364 			offset <<= PAGE_SHIFT;
365 			error = put_user(offset, (loff_t __user *)arg);
366 		} else {
367 			error = -ENOSPC;
368 		}
369 		break;
370 
371 	case SNAPSHOT_FREE_SWAP_PAGES:
372 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
373 			error = -ENODEV;
374 			break;
375 		}
376 		free_all_swap_pages(data->swap);
377 		break;
378 
379 	case SNAPSHOT_S2RAM:
380 		if (!data->frozen) {
381 			error = -EPERM;
382 			break;
383 		}
384 		/*
385 		 * Tasks are frozen and the notifiers have been called with
386 		 * PM_HIBERNATION_PREPARE
387 		 */
388 		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
389 		data->ready = false;
390 		break;
391 
392 	case SNAPSHOT_PLATFORM_SUPPORT:
393 		data->platform_support = !!arg;
394 		break;
395 
396 	case SNAPSHOT_POWER_OFF:
397 		if (data->platform_support)
398 			error = hibernation_platform_enter();
399 		break;
400 
401 	case SNAPSHOT_SET_SWAP_AREA:
402 		error = snapshot_set_swap_area(data, (void __user *)arg);
403 		break;
404 
405 	default:
406 		error = -ENOTTY;
407 
408 	}
409 
410 	unlock_device_hotplug();
411 	mutex_unlock(&system_transition_mutex);
412 
413 	return error;
414 }
415 
416 #ifdef CONFIG_COMPAT
417 static long
418 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
419 {
420 	BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
421 
422 	switch (cmd) {
423 	case SNAPSHOT_GET_IMAGE_SIZE:
424 	case SNAPSHOT_AVAIL_SWAP_SIZE:
425 	case SNAPSHOT_ALLOC_SWAP_PAGE:
426 	case SNAPSHOT_CREATE_IMAGE:
427 	case SNAPSHOT_SET_SWAP_AREA:
428 		return snapshot_ioctl(file, cmd,
429 				      (unsigned long) compat_ptr(arg));
430 	default:
431 		return snapshot_ioctl(file, cmd, arg);
432 	}
433 }
434 #endif /* CONFIG_COMPAT */
435 
436 static const struct file_operations snapshot_fops = {
437 	.open = snapshot_open,
438 	.release = snapshot_release,
439 	.read = snapshot_read,
440 	.write = snapshot_write,
441 	.llseek = no_llseek,
442 	.unlocked_ioctl = snapshot_ioctl,
443 #ifdef CONFIG_COMPAT
444 	.compat_ioctl = snapshot_compat_ioctl,
445 #endif
446 };
447 
448 static struct miscdevice snapshot_device = {
449 	.minor = SNAPSHOT_MINOR,
450 	.name = "snapshot",
451 	.fops = &snapshot_fops,
452 };
453 
454 static int __init snapshot_device_init(void)
455 {
456 	return misc_register(&snapshot_device);
457 };
458 
459 device_initcall(snapshot_device_init);
460