xref: /linux-6.15/kernel/power/user.c (revision 29bcff78) 
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 	dev_t dev;
39 } snapshot_state;
40 
41 int is_hibernate_resume_dev(dev_t dev)
42 {
43 	return hibernation_available() && snapshot_state.dev == dev;
44 }
45 
46 static int snapshot_open(struct inode *inode, struct file *filp)
47 {
48 	struct snapshot_data *data;
49 	int error, nr_calls = 0;
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 = swap_type_of(swsusp_resume_device, 0);
73 		data->mode = O_RDONLY;
74 		data->free_bitmaps = false;
75 		error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
76 		if (error)
77 			__pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
78 	} else {
79 		/*
80 		 * Resuming.  We may need to wait for the image device to
81 		 * appear.
82 		 */
83 		wait_for_device_probe();
84 
85 		data->swap = -1;
86 		data->mode = O_WRONLY;
87 		error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
88 		if (!error) {
89 			error = create_basic_memory_bitmaps();
90 			data->free_bitmaps = !error;
91 		} else
92 			nr_calls--;
93 
94 		if (error)
95 			__pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
96 	}
97 	if (error)
98 		hibernate_release();
99 
100 	data->frozen = false;
101 	data->ready = false;
102 	data->platform_support = false;
103 	data->dev = 0;
104 
105  Unlock:
106 	unlock_system_sleep();
107 
108 	return error;
109 }
110 
111 static int snapshot_release(struct inode *inode, struct file *filp)
112 {
113 	struct snapshot_data *data;
114 
115 	lock_system_sleep();
116 
117 	swsusp_free();
118 	data = filp->private_data;
119 	data->dev = 0;
120 	free_all_swap_pages(data->swap);
121 	if (data->frozen) {
122 		pm_restore_gfp_mask();
123 		free_basic_memory_bitmaps();
124 		thaw_processes();
125 	} else if (data->free_bitmaps) {
126 		free_basic_memory_bitmaps();
127 	}
128 	pm_notifier_call_chain(data->mode == O_RDONLY ?
129 			PM_POST_HIBERNATION : PM_POST_RESTORE);
130 	hibernate_release();
131 
132 	unlock_system_sleep();
133 
134 	return 0;
135 }
136 
137 static ssize_t snapshot_read(struct file *filp, char __user *buf,
138                              size_t count, loff_t *offp)
139 {
140 	struct snapshot_data *data;
141 	ssize_t res;
142 	loff_t pg_offp = *offp & ~PAGE_MASK;
143 
144 	lock_system_sleep();
145 
146 	data = filp->private_data;
147 	if (!data->ready) {
148 		res = -ENODATA;
149 		goto Unlock;
150 	}
151 	if (!pg_offp) { /* on page boundary? */
152 		res = snapshot_read_next(&data->handle);
153 		if (res <= 0)
154 			goto Unlock;
155 	} else {
156 		res = PAGE_SIZE - pg_offp;
157 	}
158 
159 	res = simple_read_from_buffer(buf, count, &pg_offp,
160 			data_of(data->handle), res);
161 	if (res > 0)
162 		*offp += res;
163 
164  Unlock:
165 	unlock_system_sleep();
166 
167 	return res;
168 }
169 
170 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
171                               size_t count, loff_t *offp)
172 {
173 	struct snapshot_data *data;
174 	ssize_t res;
175 	loff_t pg_offp = *offp & ~PAGE_MASK;
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 - pg_offp;
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 (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
254 		return -ENOTTY;
255 	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
256 		return -ENOTTY;
257 	if (!capable(CAP_SYS_ADMIN))
258 		return -EPERM;
259 
260 	if (!mutex_trylock(&system_transition_mutex))
261 		return -EBUSY;
262 
263 	lock_device_hotplug();
264 	data = filp->private_data;
265 
266 	switch (cmd) {
267 
268 	case SNAPSHOT_FREEZE:
269 		if (data->frozen)
270 			break;
271 
272 		ksys_sync_helper();
273 
274 		error = freeze_processes();
275 		if (error)
276 			break;
277 
278 		error = create_basic_memory_bitmaps();
279 		if (error)
280 			thaw_processes();
281 		else
282 			data->frozen = true;
283 
284 		break;
285 
286 	case SNAPSHOT_UNFREEZE:
287 		if (!data->frozen || data->ready)
288 			break;
289 		pm_restore_gfp_mask();
290 		free_basic_memory_bitmaps();
291 		data->free_bitmaps = false;
292 		thaw_processes();
293 		data->frozen = false;
294 		break;
295 
296 	case SNAPSHOT_CREATE_IMAGE:
297 		if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
298 			error = -EPERM;
299 			break;
300 		}
301 		pm_restore_gfp_mask();
302 		error = hibernation_snapshot(data->platform_support);
303 		if (!error) {
304 			error = put_user(in_suspend, (int __user *)arg);
305 			data->ready = !freezer_test_done && !error;
306 			freezer_test_done = false;
307 		}
308 		break;
309 
310 	case SNAPSHOT_ATOMIC_RESTORE:
311 		snapshot_write_finalize(&data->handle);
312 		if (data->mode != O_WRONLY || !data->frozen ||
313 		    !snapshot_image_loaded(&data->handle)) {
314 			error = -EPERM;
315 			break;
316 		}
317 		error = hibernation_restore(data->platform_support);
318 		break;
319 
320 	case SNAPSHOT_FREE:
321 		swsusp_free();
322 		memset(&data->handle, 0, sizeof(struct snapshot_handle));
323 		data->ready = false;
324 		/*
325 		 * It is necessary to thaw kernel threads here, because
326 		 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
327 		 * SNAPSHOT_FREE.  In that case, if kernel threads were not
328 		 * thawed, the preallocation of memory carried out by
329 		 * hibernation_snapshot() might run into problems (i.e. it
330 		 * might fail or even deadlock).
331 		 */
332 		thaw_kernel_threads();
333 		break;
334 
335 	case SNAPSHOT_PREF_IMAGE_SIZE:
336 		image_size = arg;
337 		break;
338 
339 	case SNAPSHOT_GET_IMAGE_SIZE:
340 		if (!data->ready) {
341 			error = -ENODATA;
342 			break;
343 		}
344 		size = snapshot_get_image_size();
345 		size <<= PAGE_SHIFT;
346 		error = put_user(size, (loff_t __user *)arg);
347 		break;
348 
349 	case SNAPSHOT_AVAIL_SWAP_SIZE:
350 		size = count_swap_pages(data->swap, 1);
351 		size <<= PAGE_SHIFT;
352 		error = put_user(size, (loff_t __user *)arg);
353 		break;
354 
355 	case SNAPSHOT_ALLOC_SWAP_PAGE:
356 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
357 			error = -ENODEV;
358 			break;
359 		}
360 		offset = alloc_swapdev_block(data->swap);
361 		if (offset) {
362 			offset <<= PAGE_SHIFT;
363 			error = put_user(offset, (loff_t __user *)arg);
364 		} else {
365 			error = -ENOSPC;
366 		}
367 		break;
368 
369 	case SNAPSHOT_FREE_SWAP_PAGES:
370 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
371 			error = -ENODEV;
372 			break;
373 		}
374 		free_all_swap_pages(data->swap);
375 		break;
376 
377 	case SNAPSHOT_S2RAM:
378 		if (!data->frozen) {
379 			error = -EPERM;
380 			break;
381 		}
382 		/*
383 		 * Tasks are frozen and the notifiers have been called with
384 		 * PM_HIBERNATION_PREPARE
385 		 */
386 		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
387 		data->ready = false;
388 		break;
389 
390 	case SNAPSHOT_PLATFORM_SUPPORT:
391 		data->platform_support = !!arg;
392 		break;
393 
394 	case SNAPSHOT_POWER_OFF:
395 		if (data->platform_support)
396 			error = hibernation_platform_enter();
397 		break;
398 
399 	case SNAPSHOT_SET_SWAP_AREA:
400 		error = snapshot_set_swap_area(data, (void __user *)arg);
401 		break;
402 
403 	default:
404 		error = -ENOTTY;
405 
406 	}
407 
408 	unlock_device_hotplug();
409 	mutex_unlock(&system_transition_mutex);
410 
411 	return error;
412 }
413 
414 #ifdef CONFIG_COMPAT
415 static long
416 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
417 {
418 	BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
419 
420 	switch (cmd) {
421 	case SNAPSHOT_GET_IMAGE_SIZE:
422 	case SNAPSHOT_AVAIL_SWAP_SIZE:
423 	case SNAPSHOT_ALLOC_SWAP_PAGE:
424 	case SNAPSHOT_CREATE_IMAGE:
425 	case SNAPSHOT_SET_SWAP_AREA:
426 		return snapshot_ioctl(file, cmd,
427 				      (unsigned long) compat_ptr(arg));
428 	default:
429 		return snapshot_ioctl(file, cmd, arg);
430 	}
431 }
432 #endif /* CONFIG_COMPAT */
433 
434 static const struct file_operations snapshot_fops = {
435 	.open = snapshot_open,
436 	.release = snapshot_release,
437 	.read = snapshot_read,
438 	.write = snapshot_write,
439 	.llseek = no_llseek,
440 	.unlocked_ioctl = snapshot_ioctl,
441 #ifdef CONFIG_COMPAT
442 	.compat_ioctl = snapshot_compat_ioctl,
443 #endif
444 };
445 
446 static struct miscdevice snapshot_device = {
447 	.minor = SNAPSHOT_MINOR,
448 	.name = "snapshot",
449 	.fops = &snapshot_fops,
450 };
451 
452 static int __init snapshot_device_init(void)
453 {
454 	return misc_register(&snapshot_device);
455 };
456 
457 device_initcall(snapshot_device_init);
458