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 dev_t dev;
39 } snapshot_state;
40
is_hibernate_resume_dev(dev_t dev)41 int is_hibernate_resume_dev(dev_t dev)
42 {
43 return hibernation_available() && snapshot_state.dev == dev;
44 }
45
snapshot_open(struct inode * inode,struct file * filp)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 = swap_type_of(swsusp_resume_device, 0);
73 data->mode = O_RDONLY;
74 data->free_bitmaps = false;
75 error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
76 } else {
77 /*
78 * Resuming. We may need to wait for the image device to
79 * appear.
80 */
81 wait_for_device_probe();
82
83 data->swap = -1;
84 data->mode = O_WRONLY;
85 error = pm_notifier_call_chain_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE);
86 if (!error) {
87 error = create_basic_memory_bitmaps();
88 data->free_bitmaps = !error;
89 }
90 }
91 if (error)
92 hibernate_release();
93
94 data->frozen = false;
95 data->ready = false;
96 data->platform_support = false;
97 data->dev = 0;
98
99 Unlock:
100 unlock_system_sleep();
101
102 return error;
103 }
104
snapshot_release(struct inode * inode,struct file * filp)105 static int snapshot_release(struct inode *inode, struct file *filp)
106 {
107 struct snapshot_data *data;
108
109 lock_system_sleep();
110
111 swsusp_free();
112 data = filp->private_data;
113 data->dev = 0;
114 free_all_swap_pages(data->swap);
115 if (data->frozen) {
116 pm_restore_gfp_mask();
117 free_basic_memory_bitmaps();
118 thaw_processes();
119 } else if (data->free_bitmaps) {
120 free_basic_memory_bitmaps();
121 }
122 pm_notifier_call_chain(data->mode == O_RDONLY ?
123 PM_POST_HIBERNATION : PM_POST_RESTORE);
124 hibernate_release();
125
126 unlock_system_sleep();
127
128 return 0;
129 }
130
snapshot_read(struct file * filp,char __user * buf,size_t count,loff_t * offp)131 static ssize_t snapshot_read(struct file *filp, char __user *buf,
132 size_t count, loff_t *offp)
133 {
134 struct snapshot_data *data;
135 ssize_t res;
136 loff_t pg_offp = *offp & ~PAGE_MASK;
137
138 lock_system_sleep();
139
140 data = filp->private_data;
141 if (!data->ready) {
142 res = -ENODATA;
143 goto Unlock;
144 }
145 if (!pg_offp) { /* on page boundary? */
146 res = snapshot_read_next(&data->handle);
147 if (res <= 0)
148 goto Unlock;
149 } else {
150 res = PAGE_SIZE - pg_offp;
151 }
152
153 res = simple_read_from_buffer(buf, count, &pg_offp,
154 data_of(data->handle), res);
155 if (res > 0)
156 *offp += res;
157
158 Unlock:
159 unlock_system_sleep();
160
161 return res;
162 }
163
snapshot_write(struct file * filp,const char __user * buf,size_t count,loff_t * offp)164 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
165 size_t count, loff_t *offp)
166 {
167 struct snapshot_data *data;
168 ssize_t res;
169 loff_t pg_offp = *offp & ~PAGE_MASK;
170
171 lock_system_sleep();
172
173 data = filp->private_data;
174
175 if (!pg_offp) {
176 res = snapshot_write_next(&data->handle);
177 if (res <= 0)
178 goto unlock;
179 } else {
180 res = PAGE_SIZE - pg_offp;
181 }
182
183 if (!data_of(data->handle)) {
184 res = -EINVAL;
185 goto unlock;
186 }
187
188 res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
189 buf, count);
190 if (res > 0)
191 *offp += res;
192 unlock:
193 unlock_system_sleep();
194
195 return res;
196 }
197
198 struct compat_resume_swap_area {
199 compat_loff_t offset;
200 u32 dev;
201 } __packed;
202
snapshot_set_swap_area(struct snapshot_data * data,void __user * argp)203 static int snapshot_set_swap_area(struct snapshot_data *data,
204 void __user *argp)
205 {
206 sector_t offset;
207 dev_t swdev;
208
209 if (swsusp_swap_in_use())
210 return -EPERM;
211
212 if (in_compat_syscall()) {
213 struct compat_resume_swap_area swap_area;
214
215 if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
216 return -EFAULT;
217 swdev = new_decode_dev(swap_area.dev);
218 offset = swap_area.offset;
219 } else {
220 struct resume_swap_area swap_area;
221
222 if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
223 return -EFAULT;
224 swdev = new_decode_dev(swap_area.dev);
225 offset = swap_area.offset;
226 }
227
228 /*
229 * User space encodes device types as two-byte values,
230 * so we need to recode them
231 */
232 data->swap = swap_type_of(swdev, offset);
233 if (data->swap < 0)
234 return swdev ? -ENODEV : -EINVAL;
235 data->dev = swdev;
236 return 0;
237 }
238
snapshot_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)239 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
240 unsigned long arg)
241 {
242 int error = 0;
243 struct snapshot_data *data;
244 loff_t size;
245 sector_t offset;
246
247 if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
248 return -ENOTTY;
249 if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
250 return -ENOTTY;
251 if (!capable(CAP_SYS_ADMIN))
252 return -EPERM;
253
254 if (!mutex_trylock(&system_transition_mutex))
255 return -EBUSY;
256
257 lock_device_hotplug();
258 data = filp->private_data;
259
260 switch (cmd) {
261
262 case SNAPSHOT_FREEZE:
263 if (data->frozen)
264 break;
265
266 ksys_sync_helper();
267
268 error = freeze_processes();
269 if (error)
270 break;
271
272 error = create_basic_memory_bitmaps();
273 if (error)
274 thaw_processes();
275 else
276 data->frozen = true;
277
278 break;
279
280 case SNAPSHOT_UNFREEZE:
281 if (!data->frozen || data->ready)
282 break;
283 pm_restore_gfp_mask();
284 free_basic_memory_bitmaps();
285 data->free_bitmaps = false;
286 thaw_processes();
287 data->frozen = false;
288 break;
289
290 case SNAPSHOT_CREATE_IMAGE:
291 if (data->mode != O_RDONLY || !data->frozen || data->ready) {
292 error = -EPERM;
293 break;
294 }
295 pm_restore_gfp_mask();
296 error = hibernation_snapshot(data->platform_support);
297 if (!error) {
298 error = put_user(in_suspend, (int __user *)arg);
299 data->ready = !freezer_test_done && !error;
300 freezer_test_done = false;
301 }
302 break;
303
304 case SNAPSHOT_ATOMIC_RESTORE:
305 snapshot_write_finalize(&data->handle);
306 if (data->mode != O_WRONLY || !data->frozen ||
307 !snapshot_image_loaded(&data->handle)) {
308 error = -EPERM;
309 break;
310 }
311 error = hibernation_restore(data->platform_support);
312 break;
313
314 case SNAPSHOT_FREE:
315 swsusp_free();
316 memset(&data->handle, 0, sizeof(struct snapshot_handle));
317 data->ready = false;
318 /*
319 * It is necessary to thaw kernel threads here, because
320 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
321 * SNAPSHOT_FREE. In that case, if kernel threads were not
322 * thawed, the preallocation of memory carried out by
323 * hibernation_snapshot() might run into problems (i.e. it
324 * might fail or even deadlock).
325 */
326 thaw_kernel_threads();
327 break;
328
329 case SNAPSHOT_PREF_IMAGE_SIZE:
330 image_size = arg;
331 break;
332
333 case SNAPSHOT_GET_IMAGE_SIZE:
334 if (!data->ready) {
335 error = -ENODATA;
336 break;
337 }
338 size = snapshot_get_image_size();
339 size <<= PAGE_SHIFT;
340 error = put_user(size, (loff_t __user *)arg);
341 break;
342
343 case SNAPSHOT_AVAIL_SWAP_SIZE:
344 size = count_swap_pages(data->swap, 1);
345 size <<= PAGE_SHIFT;
346 error = put_user(size, (loff_t __user *)arg);
347 break;
348
349 case SNAPSHOT_ALLOC_SWAP_PAGE:
350 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
351 error = -ENODEV;
352 break;
353 }
354 offset = alloc_swapdev_block(data->swap);
355 if (offset) {
356 offset <<= PAGE_SHIFT;
357 error = put_user(offset, (loff_t __user *)arg);
358 } else {
359 error = -ENOSPC;
360 }
361 break;
362
363 case SNAPSHOT_FREE_SWAP_PAGES:
364 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
365 error = -ENODEV;
366 break;
367 }
368 free_all_swap_pages(data->swap);
369 break;
370
371 case SNAPSHOT_S2RAM:
372 if (!data->frozen) {
373 error = -EPERM;
374 break;
375 }
376 /*
377 * Tasks are frozen and the notifiers have been called with
378 * PM_HIBERNATION_PREPARE
379 */
380 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
381 data->ready = false;
382 break;
383
384 case SNAPSHOT_PLATFORM_SUPPORT:
385 data->platform_support = !!arg;
386 break;
387
388 case SNAPSHOT_POWER_OFF:
389 if (data->platform_support)
390 error = hibernation_platform_enter();
391 break;
392
393 case SNAPSHOT_SET_SWAP_AREA:
394 error = snapshot_set_swap_area(data, (void __user *)arg);
395 break;
396
397 default:
398 error = -ENOTTY;
399
400 }
401
402 unlock_device_hotplug();
403 mutex_unlock(&system_transition_mutex);
404
405 return error;
406 }
407
408 #ifdef CONFIG_COMPAT
409 static long
snapshot_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)410 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
411 {
412 BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
413
414 switch (cmd) {
415 case SNAPSHOT_GET_IMAGE_SIZE:
416 case SNAPSHOT_AVAIL_SWAP_SIZE:
417 case SNAPSHOT_ALLOC_SWAP_PAGE:
418 case SNAPSHOT_CREATE_IMAGE:
419 case SNAPSHOT_SET_SWAP_AREA:
420 return snapshot_ioctl(file, cmd,
421 (unsigned long) compat_ptr(arg));
422 default:
423 return snapshot_ioctl(file, cmd, arg);
424 }
425 }
426 #endif /* CONFIG_COMPAT */
427
428 static const struct file_operations snapshot_fops = {
429 .open = snapshot_open,
430 .release = snapshot_release,
431 .read = snapshot_read,
432 .write = snapshot_write,
433 .llseek = no_llseek,
434 .unlocked_ioctl = snapshot_ioctl,
435 #ifdef CONFIG_COMPAT
436 .compat_ioctl = snapshot_compat_ioctl,
437 #endif
438 };
439
440 static struct miscdevice snapshot_device = {
441 .minor = SNAPSHOT_MINOR,
442 .name = "snapshot",
443 .fops = &snapshot_fops,
444 };
445
snapshot_device_init(void)446 static int __init snapshot_device_init(void)
447 {
448 return misc_register(&snapshot_device);
449 };
450
451 device_initcall(snapshot_device_init);
452