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