xref: /openbmc/linux/kernel/power/user.c (revision a44e4f3a) 
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 #define SNAPSHOT_MINOR	231
31 
32 static struct snapshot_data {
33 	struct snapshot_handle handle;
34 	int swap;
35 	int mode;
36 	bool frozen;
37 	bool ready;
38 	bool platform_support;
39 	bool free_bitmaps;
40 } snapshot_state;
41 
42 atomic_t snapshot_device_available = ATOMIC_INIT(1);
43 
44 static int snapshot_open(struct inode *inode, struct file *filp)
45 {
46 	struct snapshot_data *data;
47 	int error, nr_calls = 0;
48 
49 	if (!hibernation_available())
50 		return -EPERM;
51 
52 	lock_system_sleep();
53 
54 	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
55 		error = -EBUSY;
56 		goto Unlock;
57 	}
58 
59 	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
60 		atomic_inc(&snapshot_device_available);
61 		error = -ENOSYS;
62 		goto Unlock;
63 	}
64 	nonseekable_open(inode, filp);
65 	data = &snapshot_state;
66 	filp->private_data = data;
67 	memset(&data->handle, 0, sizeof(struct snapshot_handle));
68 	if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
69 		/* Hibernating.  The image device should be accessible. */
70 		data->swap = swsusp_resume_device ?
71 			swap_type_of(swsusp_resume_device, 0, NULL) : -1;
72 		data->mode = O_RDONLY;
73 		data->free_bitmaps = false;
74 		error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
75 		if (error)
76 			__pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
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(PM_RESTORE_PREPARE, -1, &nr_calls);
87 		if (!error) {
88 			error = create_basic_memory_bitmaps();
89 			data->free_bitmaps = !error;
90 		} else
91 			nr_calls--;
92 
93 		if (error)
94 			__pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
95 	}
96 	if (error)
97 		atomic_inc(&snapshot_device_available);
98 
99 	data->frozen = false;
100 	data->ready = false;
101 	data->platform_support = false;
102 
103  Unlock:
104 	unlock_system_sleep();
105 
106 	return error;
107 }
108 
109 static int snapshot_release(struct inode *inode, struct file *filp)
110 {
111 	struct snapshot_data *data;
112 
113 	lock_system_sleep();
114 
115 	swsusp_free();
116 	data = filp->private_data;
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 	atomic_inc(&snapshot_device_available);
128 
129 	unlock_system_sleep();
130 
131 	return 0;
132 }
133 
134 static ssize_t snapshot_read(struct file *filp, char __user *buf,
135                              size_t count, loff_t *offp)
136 {
137 	struct snapshot_data *data;
138 	ssize_t res;
139 	loff_t pg_offp = *offp & ~PAGE_MASK;
140 
141 	lock_system_sleep();
142 
143 	data = filp->private_data;
144 	if (!data->ready) {
145 		res = -ENODATA;
146 		goto Unlock;
147 	}
148 	if (!pg_offp) { /* on page boundary? */
149 		res = snapshot_read_next(&data->handle);
150 		if (res <= 0)
151 			goto Unlock;
152 	} else {
153 		res = PAGE_SIZE - pg_offp;
154 	}
155 
156 	res = simple_read_from_buffer(buf, count, &pg_offp,
157 			data_of(data->handle), res);
158 	if (res > 0)
159 		*offp += res;
160 
161  Unlock:
162 	unlock_system_sleep();
163 
164 	return res;
165 }
166 
167 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
168                               size_t count, loff_t *offp)
169 {
170 	struct snapshot_data *data;
171 	ssize_t res;
172 	loff_t pg_offp = *offp & ~PAGE_MASK;
173 
174 	lock_system_sleep();
175 
176 	data = filp->private_data;
177 
178 	if (!pg_offp) {
179 		res = snapshot_write_next(&data->handle);
180 		if (res <= 0)
181 			goto unlock;
182 	} else {
183 		res = PAGE_SIZE - pg_offp;
184 	}
185 
186 	if (!data_of(data->handle)) {
187 		res = -EINVAL;
188 		goto unlock;
189 	}
190 
191 	res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
192 			buf, count);
193 	if (res > 0)
194 		*offp += res;
195 unlock:
196 	unlock_system_sleep();
197 
198 	return res;
199 }
200 
201 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
202 							unsigned long arg)
203 {
204 	int error = 0;
205 	struct snapshot_data *data;
206 	loff_t size;
207 	sector_t offset;
208 
209 	if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
210 		return -ENOTTY;
211 	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
212 		return -ENOTTY;
213 	if (!capable(CAP_SYS_ADMIN))
214 		return -EPERM;
215 
216 	if (!mutex_trylock(&system_transition_mutex))
217 		return -EBUSY;
218 
219 	lock_device_hotplug();
220 	data = filp->private_data;
221 
222 	switch (cmd) {
223 
224 	case SNAPSHOT_FREEZE:
225 		if (data->frozen)
226 			break;
227 
228 		ksys_sync_helper();
229 
230 		error = freeze_processes();
231 		if (error)
232 			break;
233 
234 		error = create_basic_memory_bitmaps();
235 		if (error)
236 			thaw_processes();
237 		else
238 			data->frozen = true;
239 
240 		break;
241 
242 	case SNAPSHOT_UNFREEZE:
243 		if (!data->frozen || data->ready)
244 			break;
245 		pm_restore_gfp_mask();
246 		free_basic_memory_bitmaps();
247 		data->free_bitmaps = false;
248 		thaw_processes();
249 		data->frozen = false;
250 		break;
251 
252 	case SNAPSHOT_CREATE_IMAGE:
253 		if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
254 			error = -EPERM;
255 			break;
256 		}
257 		pm_restore_gfp_mask();
258 		error = hibernation_snapshot(data->platform_support);
259 		if (!error) {
260 			error = put_user(in_suspend, (int __user *)arg);
261 			data->ready = !freezer_test_done && !error;
262 			freezer_test_done = false;
263 		}
264 		break;
265 
266 	case SNAPSHOT_ATOMIC_RESTORE:
267 		snapshot_write_finalize(&data->handle);
268 		if (data->mode != O_WRONLY || !data->frozen ||
269 		    !snapshot_image_loaded(&data->handle)) {
270 			error = -EPERM;
271 			break;
272 		}
273 		error = hibernation_restore(data->platform_support);
274 		break;
275 
276 	case SNAPSHOT_FREE:
277 		swsusp_free();
278 		memset(&data->handle, 0, sizeof(struct snapshot_handle));
279 		data->ready = false;
280 		/*
281 		 * It is necessary to thaw kernel threads here, because
282 		 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
283 		 * SNAPSHOT_FREE.  In that case, if kernel threads were not
284 		 * thawed, the preallocation of memory carried out by
285 		 * hibernation_snapshot() might run into problems (i.e. it
286 		 * might fail or even deadlock).
287 		 */
288 		thaw_kernel_threads();
289 		break;
290 
291 	case SNAPSHOT_PREF_IMAGE_SIZE:
292 		image_size = arg;
293 		break;
294 
295 	case SNAPSHOT_GET_IMAGE_SIZE:
296 		if (!data->ready) {
297 			error = -ENODATA;
298 			break;
299 		}
300 		size = snapshot_get_image_size();
301 		size <<= PAGE_SHIFT;
302 		error = put_user(size, (loff_t __user *)arg);
303 		break;
304 
305 	case SNAPSHOT_AVAIL_SWAP_SIZE:
306 		size = count_swap_pages(data->swap, 1);
307 		size <<= PAGE_SHIFT;
308 		error = put_user(size, (loff_t __user *)arg);
309 		break;
310 
311 	case SNAPSHOT_ALLOC_SWAP_PAGE:
312 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
313 			error = -ENODEV;
314 			break;
315 		}
316 		offset = alloc_swapdev_block(data->swap);
317 		if (offset) {
318 			offset <<= PAGE_SHIFT;
319 			error = put_user(offset, (loff_t __user *)arg);
320 		} else {
321 			error = -ENOSPC;
322 		}
323 		break;
324 
325 	case SNAPSHOT_FREE_SWAP_PAGES:
326 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
327 			error = -ENODEV;
328 			break;
329 		}
330 		free_all_swap_pages(data->swap);
331 		break;
332 
333 	case SNAPSHOT_S2RAM:
334 		if (!data->frozen) {
335 			error = -EPERM;
336 			break;
337 		}
338 		/*
339 		 * Tasks are frozen and the notifiers have been called with
340 		 * PM_HIBERNATION_PREPARE
341 		 */
342 		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
343 		data->ready = false;
344 		break;
345 
346 	case SNAPSHOT_PLATFORM_SUPPORT:
347 		data->platform_support = !!arg;
348 		break;
349 
350 	case SNAPSHOT_POWER_OFF:
351 		if (data->platform_support)
352 			error = hibernation_platform_enter();
353 		break;
354 
355 	case SNAPSHOT_SET_SWAP_AREA:
356 		if (swsusp_swap_in_use()) {
357 			error = -EPERM;
358 		} else {
359 			struct resume_swap_area swap_area;
360 			dev_t swdev;
361 
362 			error = copy_from_user(&swap_area, (void __user *)arg,
363 					sizeof(struct resume_swap_area));
364 			if (error) {
365 				error = -EFAULT;
366 				break;
367 			}
368 
369 			/*
370 			 * User space encodes device types as two-byte values,
371 			 * so we need to recode them
372 			 */
373 			swdev = new_decode_dev(swap_area.dev);
374 			if (swdev) {
375 				offset = swap_area.offset;
376 				data->swap = swap_type_of(swdev, offset, NULL);
377 				if (data->swap < 0)
378 					error = -ENODEV;
379 			} else {
380 				data->swap = -1;
381 				error = -EINVAL;
382 			}
383 		}
384 		break;
385 
386 	default:
387 		error = -ENOTTY;
388 
389 	}
390 
391 	unlock_device_hotplug();
392 	mutex_unlock(&system_transition_mutex);
393 
394 	return error;
395 }
396 
397 #ifdef CONFIG_COMPAT
398 
399 struct compat_resume_swap_area {
400 	compat_loff_t offset;
401 	u32 dev;
402 } __packed;
403 
404 static long
405 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
406 {
407 	BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
408 
409 	switch (cmd) {
410 	case SNAPSHOT_GET_IMAGE_SIZE:
411 	case SNAPSHOT_AVAIL_SWAP_SIZE:
412 	case SNAPSHOT_ALLOC_SWAP_PAGE: {
413 		compat_loff_t __user *uoffset = compat_ptr(arg);
414 		loff_t offset;
415 		mm_segment_t old_fs;
416 		int err;
417 
418 		old_fs = get_fs();
419 		set_fs(KERNEL_DS);
420 		err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
421 		set_fs(old_fs);
422 		if (!err && put_user(offset, uoffset))
423 			err = -EFAULT;
424 		return err;
425 	}
426 
427 	case SNAPSHOT_CREATE_IMAGE:
428 		return snapshot_ioctl(file, cmd,
429 				      (unsigned long) compat_ptr(arg));
430 
431 	case SNAPSHOT_SET_SWAP_AREA: {
432 		struct compat_resume_swap_area __user *u_swap_area =
433 			compat_ptr(arg);
434 		struct resume_swap_area swap_area;
435 		mm_segment_t old_fs;
436 		int err;
437 
438 		err = get_user(swap_area.offset, &u_swap_area->offset);
439 		err |= get_user(swap_area.dev, &u_swap_area->dev);
440 		if (err)
441 			return -EFAULT;
442 		old_fs = get_fs();
443 		set_fs(KERNEL_DS);
444 		err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
445 				     (unsigned long) &swap_area);
446 		set_fs(old_fs);
447 		return err;
448 	}
449 
450 	default:
451 		return snapshot_ioctl(file, cmd, arg);
452 	}
453 }
454 
455 #endif /* CONFIG_COMPAT */
456 
457 static const struct file_operations snapshot_fops = {
458 	.open = snapshot_open,
459 	.release = snapshot_release,
460 	.read = snapshot_read,
461 	.write = snapshot_write,
462 	.llseek = no_llseek,
463 	.unlocked_ioctl = snapshot_ioctl,
464 #ifdef CONFIG_COMPAT
465 	.compat_ioctl = snapshot_compat_ioctl,
466 #endif
467 };
468 
469 static struct miscdevice snapshot_device = {
470 	.minor = SNAPSHOT_MINOR,
471 	.name = "snapshot",
472 	.fops = &snapshot_fops,
473 };
474 
475 static int __init snapshot_device_init(void)
476 {
477 	return misc_register(&snapshot_device);
478 };
479 
480 device_initcall(snapshot_device_init);
481