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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
29static bool need_wait;
30
31static struct snapshot_data {
32 struct snapshot_handle handle;
33 int swap;
34 int mode;
35 bool frozen;
36 bool ready;
37 bool platform_support;
38 bool free_bitmaps;
39 dev_t dev;
40} snapshot_state;
41
42int is_hibernate_resume_dev(dev_t dev)
43{
44 return hibernation_available() && snapshot_state.dev == dev;
45}
46
47static int snapshot_open(struct inode *inode, struct file *filp)
48{
49 struct snapshot_data *data;
50 unsigned int sleep_flags;
51 int error;
52
53 if (!hibernation_available())
54 return -EPERM;
55
56 sleep_flags = lock_system_sleep();
57
58 if (!hibernate_acquire()) {
59 error = -EBUSY;
60 goto Unlock;
61 }
62
63 if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
64 hibernate_release();
65 error = -ENOSYS;
66 goto Unlock;
67 }
68 nonseekable_open(inode, filp);
69 data = &snapshot_state;
70 filp->private_data = data;
71 memset(&data->handle, 0, sizeof(struct snapshot_handle));
72 if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
73 /* Hibernating. The image device should be accessible. */
74 data->swap = pin_hibernation_swap_type(swsusp_resume_device, 0);
75 data->mode = O_RDONLY;
76 data->free_bitmaps = false;
77 error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
78 } else {
79 /*
80 * Resuming. We may need to wait for the image device to
81 * appear.
82 */
83 need_wait = true;
84
85 data->swap = -1;
86 data->mode = O_WRONLY;
87 error = pm_notifier_call_chain_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE);
88 if (!error) {
89 error = create_basic_memory_bitmaps();
90 data->free_bitmaps = !error;
91 }
92 }
93 if (error) {
94 unpin_hibernation_swap_type(data->swap);
95 hibernate_release();
96 }
97
98 data->frozen = false;
99 data->ready = false;
100 data->platform_support = false;
101 data->dev = 0;
102
103 Unlock:
104 unlock_system_sleep(sleep_flags);
105
106 return error;
107}
108
109static int snapshot_release(struct inode *inode, struct file *filp)
110{
111 struct snapshot_data *data;
112 unsigned int sleep_flags;
113
114 sleep_flags = lock_system_sleep();
115
116 swsusp_free();
117 data = filp->private_data;
118 data->dev = 0;
119 free_all_swap_pages(data->swap);
120 unpin_hibernation_swap_type(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(sleep_flags);
133
134 return 0;
135}
136
137static ssize_t snapshot_read(struct file *filp, char __user *buf,
138 size_t count, loff_t *offp)
139{
140 loff_t pg_offp = *offp & ~PAGE_MASK;
141 struct snapshot_data *data;
142 unsigned int sleep_flags;
143 ssize_t res;
144
145 sleep_flags = lock_system_sleep();
146
147 data = filp->private_data;
148 if (!data->ready) {
149 res = -ENODATA;
150 goto Unlock;
151 }
152 if (!pg_offp) { /* on page boundary? */
153 res = snapshot_read_next(&data->handle);
154 if (res <= 0)
155 goto Unlock;
156 } else {
157 res = PAGE_SIZE - pg_offp;
158 }
159
160 res = simple_read_from_buffer(buf, count, &pg_offp,
161 data_of(data->handle), res);
162 if (res > 0)
163 *offp += res;
164
165 Unlock:
166 unlock_system_sleep(sleep_flags);
167
168 return res;
169}
170
171static ssize_t snapshot_write(struct file *filp, const char __user *buf,
172 size_t count, loff_t *offp)
173{
174 loff_t pg_offp = *offp & ~PAGE_MASK;
175 struct snapshot_data *data;
176 unsigned long sleep_flags;
177 ssize_t res;
178
179 if (need_wait) {
180 wait_for_device_probe();
181 need_wait = false;
182 }
183
184 sleep_flags = lock_system_sleep();
185
186 data = filp->private_data;
187
188 if (!pg_offp) {
189 res = snapshot_write_next(&data->handle);
190 if (res <= 0)
191 goto unlock;
192 } else {
193 res = PAGE_SIZE;
194 }
195
196 if (!data_of(data->handle)) {
197 res = -EINVAL;
198 goto unlock;
199 }
200
201 res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
202 buf, count);
203 if (res > 0)
204 *offp += res;
205unlock:
206 unlock_system_sleep(sleep_flags);
207
208 return res;
209}
210
211struct compat_resume_swap_area {
212 compat_loff_t offset;
213 u32 dev;
214} __packed;
215
216static int snapshot_set_swap_area(struct snapshot_data *data,
217 void __user *argp)
218{
219 sector_t offset;
220 dev_t swdev;
221
222 if (swsusp_swap_in_use())
223 return -EPERM;
224
225 if (in_compat_syscall()) {
226 struct compat_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 } else {
233 struct resume_swap_area swap_area;
234
235 if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
236 return -EFAULT;
237 swdev = new_decode_dev(swap_area.dev);
238 offset = swap_area.offset;
239 }
240
241 /*
242 * Unpin the swap device if a swap area was already
243 * set by SNAPSHOT_SET_SWAP_AREA.
244 */
245 unpin_hibernation_swap_type(data->swap);
246
247 /*
248 * User space encodes device types as two-byte values,
249 * so we need to recode them
250 */
251 data->swap = pin_hibernation_swap_type(swdev, offset);
252 if (data->swap < 0)
253 return swdev ? -ENODEV : -EINVAL;
254 data->dev = swdev;
255 return 0;
256}
257
258static long snapshot_ioctl(struct file *filp, unsigned int cmd,
259 unsigned long arg)
260{
261 int error = 0;
262 struct snapshot_data *data;
263 loff_t size;
264 sector_t offset;
265
266 if (need_wait) {
267 wait_for_device_probe();
268 need_wait = false;
269 }
270
271 if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
272 return -ENOTTY;
273 if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
274 return -ENOTTY;
275 if (!capable(CAP_SYS_ADMIN))
276 return -EPERM;
277
278 if (!mutex_trylock(&system_transition_mutex))
279 return -EBUSY;
280
281 lock_device_hotplug();
282 data = filp->private_data;
283
284 switch (cmd) {
285
286 case SNAPSHOT_FREEZE:
287 if (data->frozen)
288 break;
289
290 error = pm_sleep_fs_sync();
291 if (error)
292 break;
293
294 error = freeze_processes();
295 if (error)
296 break;
297
298 error = create_basic_memory_bitmaps();
299 if (error)
300 thaw_processes();
301 else
302 data->frozen = true;
303
304 break;
305
306 case SNAPSHOT_UNFREEZE:
307 if (!data->frozen || data->ready)
308 break;
309 pm_restore_gfp_mask();
310 free_basic_memory_bitmaps();
311 data->free_bitmaps = false;
312 thaw_processes();
313 data->frozen = false;
314 break;
315
316 case SNAPSHOT_CREATE_IMAGE:
317 if (data->mode != O_RDONLY || !data->frozen || data->ready) {
318 error = -EPERM;
319 break;
320 }
321 pm_restore_gfp_mask();
322 error = hibernation_snapshot(data->platform_support);
323 if (!error) {
324 error = put_user(in_suspend, (int __user *)arg);
325 data->ready = !freezer_test_done && !error;
326 freezer_test_done = false;
327 }
328 break;
329
330 case SNAPSHOT_ATOMIC_RESTORE:
331 error = snapshot_write_finalize(&data->handle);
332 if (error)
333 break;
334 if (data->mode != O_WRONLY || !data->frozen) {
335 error = -EPERM;
336 break;
337 }
338 if (!snapshot_image_loaded(&data->handle)) {
339 error = -ENODATA;
340 break;
341 }
342 error = hibernation_restore(data->platform_support);
343 break;
344
345 case SNAPSHOT_FREE:
346 swsusp_free();
347 memset(&data->handle, 0, sizeof(struct snapshot_handle));
348 data->ready = false;
349 /*
350 * It is necessary to thaw kernel threads here, because
351 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
352 * SNAPSHOT_FREE. In that case, if kernel threads were not
353 * thawed, the preallocation of memory carried out by
354 * hibernation_snapshot() might run into problems (i.e. it
355 * might fail or even deadlock).
356 */
357 thaw_kernel_threads();
358 break;
359
360 case SNAPSHOT_PREF_IMAGE_SIZE:
361 image_size = arg;
362 break;
363
364 case SNAPSHOT_GET_IMAGE_SIZE:
365 if (!data->ready) {
366 error = -ENODATA;
367 break;
368 }
369 size = snapshot_get_image_size();
370 size <<= PAGE_SHIFT;
371 error = put_user(size, (loff_t __user *)arg);
372 break;
373
374 case SNAPSHOT_AVAIL_SWAP_SIZE:
375 size = count_swap_pages(data->swap, 1);
376 size <<= PAGE_SHIFT;
377 error = put_user(size, (loff_t __user *)arg);
378 break;
379
380 case SNAPSHOT_ALLOC_SWAP_PAGE:
381 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
382 error = -ENODEV;
383 break;
384 }
385 offset = alloc_swapdev_block(data->swap);
386 if (offset) {
387 offset <<= PAGE_SHIFT;
388 error = put_user(offset, (loff_t __user *)arg);
389 } else {
390 error = -ENOSPC;
391 }
392 break;
393
394 case SNAPSHOT_FREE_SWAP_PAGES:
395 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
396 error = -ENODEV;
397 break;
398 }
399 free_all_swap_pages(data->swap);
400 break;
401
402 case SNAPSHOT_S2RAM:
403 if (!data->frozen) {
404 error = -EPERM;
405 break;
406 }
407 /*
408 * Tasks are frozen and the notifiers have been called with
409 * PM_HIBERNATION_PREPARE
410 */
411 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
412 data->ready = false;
413 break;
414
415 case SNAPSHOT_PLATFORM_SUPPORT:
416 data->platform_support = !!arg;
417 break;
418
419 case SNAPSHOT_POWER_OFF:
420 if (data->platform_support)
421 error = hibernation_platform_enter();
422 break;
423
424 case SNAPSHOT_SET_SWAP_AREA:
425 error = snapshot_set_swap_area(data, (void __user *)arg);
426 break;
427
428 default:
429 error = -ENOTTY;
430
431 }
432
433 unlock_device_hotplug();
434 mutex_unlock(&system_transition_mutex);
435
436 return error;
437}
438
439#ifdef CONFIG_COMPAT
440static long
441snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
442{
443 BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
444
445 switch (cmd) {
446 case SNAPSHOT_GET_IMAGE_SIZE:
447 case SNAPSHOT_AVAIL_SWAP_SIZE:
448 case SNAPSHOT_ALLOC_SWAP_PAGE:
449 case SNAPSHOT_CREATE_IMAGE:
450 case SNAPSHOT_SET_SWAP_AREA:
451 return snapshot_ioctl(file, cmd,
452 (unsigned long) compat_ptr(arg));
453 default:
454 return snapshot_ioctl(file, cmd, arg);
455 }
456}
457#endif /* CONFIG_COMPAT */
458
459static const struct file_operations snapshot_fops = {
460 .open = snapshot_open,
461 .release = snapshot_release,
462 .read = snapshot_read,
463 .write = snapshot_write,
464 .unlocked_ioctl = snapshot_ioctl,
465#ifdef CONFIG_COMPAT
466 .compat_ioctl = snapshot_compat_ioctl,
467#endif
468};
469
470static struct miscdevice snapshot_device = {
471 .minor = SNAPSHOT_MINOR,
472 .name = "snapshot",
473 .fops = &snapshot_fops,
474};
475
476static int __init snapshot_device_init(void)
477{
478 return misc_register(&snapshot_device);
479};
480
481device_initcall(snapshot_device_init);