xref: /openbmc/linux/kernel/power/user.c (revision 12a5b00a) 
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 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 } snapshot_state;
39 
40 atomic_t snapshot_device_available = ATOMIC_INIT(1);
41 
42 static int snapshot_open(struct inode *inode, struct file *filp)
43 {
44 	struct snapshot_data *data;
45 	int error, nr_calls = 0;
46 
47 	if (!hibernation_available())
48 		return -EPERM;
49 
50 	lock_system_sleep();
51 
52 	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
53 		error = -EBUSY;
54 		goto Unlock;
55 	}
56 
57 	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
58 		atomic_inc(&snapshot_device_available);
59 		error = -ENOSYS;
60 		goto Unlock;
61 	}
62 	nonseekable_open(inode, filp);
63 	data = &snapshot_state;
64 	filp->private_data = data;
65 	memset(&data->handle, 0, sizeof(struct snapshot_handle));
66 	if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
67 		/* Hibernating.  The image device should be accessible. */
68 		data->swap = swsusp_resume_device ?
69 			swap_type_of(swsusp_resume_device, 0, NULL) : -1;
70 		data->mode = O_RDONLY;
71 		data->free_bitmaps = false;
72 		error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
73 		if (error)
74 			__pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
75 	} else {
76 		/*
77 		 * Resuming.  We may need to wait for the image device to
78 		 * appear.
79 		 */
80 		wait_for_device_probe();
81 
82 		data->swap = -1;
83 		data->mode = O_WRONLY;
84 		error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
85 		if (!error) {
86 			error = create_basic_memory_bitmaps();
87 			data->free_bitmaps = !error;
88 		} else
89 			nr_calls--;
90 
91 		if (error)
92 			__pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
93 	}
94 	if (error)
95 		atomic_inc(&snapshot_device_available);
96 
97 	data->frozen = false;
98 	data->ready = false;
99 	data->platform_support = false;
100 
101  Unlock:
102 	unlock_system_sleep();
103 
104 	return error;
105 }
106 
107 static int snapshot_release(struct inode *inode, struct file *filp)
108 {
109 	struct snapshot_data *data;
110 
111 	lock_system_sleep();
112 
113 	swsusp_free();
114 	data = filp->private_data;
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 	atomic_inc(&snapshot_device_available);
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 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
200 							unsigned long arg)
201 {
202 	int error = 0;
203 	struct snapshot_data *data;
204 	loff_t size;
205 	sector_t offset;
206 
207 	if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
208 		return -ENOTTY;
209 	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
210 		return -ENOTTY;
211 	if (!capable(CAP_SYS_ADMIN))
212 		return -EPERM;
213 
214 	if (!mutex_trylock(&system_transition_mutex))
215 		return -EBUSY;
216 
217 	lock_device_hotplug();
218 	data = filp->private_data;
219 
220 	switch (cmd) {
221 
222 	case SNAPSHOT_FREEZE:
223 		if (data->frozen)
224 			break;
225 
226 		ksys_sync_helper();
227 
228 		error = freeze_processes();
229 		if (error)
230 			break;
231 
232 		error = create_basic_memory_bitmaps();
233 		if (error)
234 			thaw_processes();
235 		else
236 			data->frozen = true;
237 
238 		break;
239 
240 	case SNAPSHOT_UNFREEZE:
241 		if (!data->frozen || data->ready)
242 			break;
243 		pm_restore_gfp_mask();
244 		free_basic_memory_bitmaps();
245 		data->free_bitmaps = false;
246 		thaw_processes();
247 		data->frozen = false;
248 		break;
249 
250 	case SNAPSHOT_CREATE_IMAGE:
251 		if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
252 			error = -EPERM;
253 			break;
254 		}
255 		pm_restore_gfp_mask();
256 		error = hibernation_snapshot(data->platform_support);
257 		if (!error) {
258 			error = put_user(in_suspend, (int __user *)arg);
259 			data->ready = !freezer_test_done && !error;
260 			freezer_test_done = false;
261 		}
262 		break;
263 
264 	case SNAPSHOT_ATOMIC_RESTORE:
265 		snapshot_write_finalize(&data->handle);
266 		if (data->mode != O_WRONLY || !data->frozen ||
267 		    !snapshot_image_loaded(&data->handle)) {
268 			error = -EPERM;
269 			break;
270 		}
271 		error = hibernation_restore(data->platform_support);
272 		break;
273 
274 	case SNAPSHOT_FREE:
275 		swsusp_free();
276 		memset(&data->handle, 0, sizeof(struct snapshot_handle));
277 		data->ready = false;
278 		/*
279 		 * It is necessary to thaw kernel threads here, because
280 		 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
281 		 * SNAPSHOT_FREE.  In that case, if kernel threads were not
282 		 * thawed, the preallocation of memory carried out by
283 		 * hibernation_snapshot() might run into problems (i.e. it
284 		 * might fail or even deadlock).
285 		 */
286 		thaw_kernel_threads();
287 		break;
288 
289 	case SNAPSHOT_PREF_IMAGE_SIZE:
290 		image_size = arg;
291 		break;
292 
293 	case SNAPSHOT_GET_IMAGE_SIZE:
294 		if (!data->ready) {
295 			error = -ENODATA;
296 			break;
297 		}
298 		size = snapshot_get_image_size();
299 		size <<= PAGE_SHIFT;
300 		error = put_user(size, (loff_t __user *)arg);
301 		break;
302 
303 	case SNAPSHOT_AVAIL_SWAP_SIZE:
304 		size = count_swap_pages(data->swap, 1);
305 		size <<= PAGE_SHIFT;
306 		error = put_user(size, (loff_t __user *)arg);
307 		break;
308 
309 	case SNAPSHOT_ALLOC_SWAP_PAGE:
310 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
311 			error = -ENODEV;
312 			break;
313 		}
314 		offset = alloc_swapdev_block(data->swap);
315 		if (offset) {
316 			offset <<= PAGE_SHIFT;
317 			error = put_user(offset, (loff_t __user *)arg);
318 		} else {
319 			error = -ENOSPC;
320 		}
321 		break;
322 
323 	case SNAPSHOT_FREE_SWAP_PAGES:
324 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
325 			error = -ENODEV;
326 			break;
327 		}
328 		free_all_swap_pages(data->swap);
329 		break;
330 
331 	case SNAPSHOT_S2RAM:
332 		if (!data->frozen) {
333 			error = -EPERM;
334 			break;
335 		}
336 		/*
337 		 * Tasks are frozen and the notifiers have been called with
338 		 * PM_HIBERNATION_PREPARE
339 		 */
340 		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
341 		data->ready = false;
342 		break;
343 
344 	case SNAPSHOT_PLATFORM_SUPPORT:
345 		data->platform_support = !!arg;
346 		break;
347 
348 	case SNAPSHOT_POWER_OFF:
349 		if (data->platform_support)
350 			error = hibernation_platform_enter();
351 		break;
352 
353 	case SNAPSHOT_SET_SWAP_AREA:
354 		if (swsusp_swap_in_use()) {
355 			error = -EPERM;
356 		} else {
357 			struct resume_swap_area swap_area;
358 			dev_t swdev;
359 
360 			error = copy_from_user(&swap_area, (void __user *)arg,
361 					sizeof(struct resume_swap_area));
362 			if (error) {
363 				error = -EFAULT;
364 				break;
365 			}
366 
367 			/*
368 			 * User space encodes device types as two-byte values,
369 			 * so we need to recode them
370 			 */
371 			swdev = new_decode_dev(swap_area.dev);
372 			if (swdev) {
373 				offset = swap_area.offset;
374 				data->swap = swap_type_of(swdev, offset, NULL);
375 				if (data->swap < 0)
376 					error = -ENODEV;
377 			} else {
378 				data->swap = -1;
379 				error = -EINVAL;
380 			}
381 		}
382 		break;
383 
384 	default:
385 		error = -ENOTTY;
386 
387 	}
388 
389 	unlock_device_hotplug();
390 	mutex_unlock(&system_transition_mutex);
391 
392 	return error;
393 }
394 
395 #ifdef CONFIG_COMPAT
396 
397 struct compat_resume_swap_area {
398 	compat_loff_t offset;
399 	u32 dev;
400 } __packed;
401 
402 static long
403 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
404 {
405 	BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
406 
407 	switch (cmd) {
408 	case SNAPSHOT_GET_IMAGE_SIZE:
409 	case SNAPSHOT_AVAIL_SWAP_SIZE:
410 	case SNAPSHOT_ALLOC_SWAP_PAGE:
411 	case SNAPSHOT_CREATE_IMAGE:
412 		return snapshot_ioctl(file, cmd,
413 				      (unsigned long) compat_ptr(arg));
414 
415 	case SNAPSHOT_SET_SWAP_AREA: {
416 		struct compat_resume_swap_area __user *u_swap_area =
417 			compat_ptr(arg);
418 		struct resume_swap_area swap_area;
419 		mm_segment_t old_fs;
420 		int err;
421 
422 		err = get_user(swap_area.offset, &u_swap_area->offset);
423 		err |= get_user(swap_area.dev, &u_swap_area->dev);
424 		if (err)
425 			return -EFAULT;
426 		old_fs = get_fs();
427 		set_fs(KERNEL_DS);
428 		err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
429 				     (unsigned long) &swap_area);
430 		set_fs(old_fs);
431 		return err;
432 	}
433 
434 	default:
435 		return snapshot_ioctl(file, cmd, arg);
436 	}
437 }
438 
439 #endif /* CONFIG_COMPAT */
440 
441 static const struct file_operations snapshot_fops = {
442 	.open = snapshot_open,
443 	.release = snapshot_release,
444 	.read = snapshot_read,
445 	.write = snapshot_write,
446 	.llseek = no_llseek,
447 	.unlocked_ioctl = snapshot_ioctl,
448 #ifdef CONFIG_COMPAT
449 	.compat_ioctl = snapshot_compat_ioctl,
450 #endif
451 };
452 
453 static struct miscdevice snapshot_device = {
454 	.minor = SNAPSHOT_MINOR,
455 	.name = "snapshot",
456 	.fops = &snapshot_fops,
457 };
458 
459 static int __init snapshot_device_init(void)
460 {
461 	return misc_register(&snapshot_device);
462 };
463 
464 device_initcall(snapshot_device_init);
465