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 static bool need_wait;
30
31 static 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
is_hibernate_resume_dev(dev_t dev)42 int is_hibernate_resume_dev(dev_t dev)
43 {
44 return hibernation_available() && snapshot_state.dev == dev;
45 }
46
snapshot_open(struct inode * inode,struct file * filp)47 static int snapshot_open(struct inode *inode, struct file *filp)
48 {
49 struct snapshot_data *data;
50 int error;
51
52 if (!hibernation_available())
53 return -EPERM;
54
55 lock_system_sleep();
56
57 if (!hibernate_acquire()) {
58 error = -EBUSY;
59 goto Unlock;
60 }
61
62 if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
63 hibernate_release();
64 error = -ENOSYS;
65 goto Unlock;
66 }
67 nonseekable_open(inode, filp);
68 data = &snapshot_state;
69 filp->private_data = data;
70 memset(&data->handle, 0, sizeof(struct snapshot_handle));
71 if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
72 /* Hibernating. The image device should be accessible. */
73 data->swap = swap_type_of(swsusp_resume_device, 0);
74 data->mode = O_RDONLY;
75 data->free_bitmaps = false;
76 error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
77 } else {
78 /*
79 * Resuming. We may need to wait for the image device to
80 * appear.
81 */
82 need_wait = true;
83
84 data->swap = -1;
85 data->mode = O_WRONLY;
86 error = pm_notifier_call_chain_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE);
87 if (!error) {
88 error = create_basic_memory_bitmaps();
89 data->free_bitmaps = !error;
90 }
91 }
92 if (error)
93 hibernate_release();
94
95 data->frozen = false;
96 data->ready = false;
97 data->platform_support = false;
98 data->dev = 0;
99
100 Unlock:
101 unlock_system_sleep();
102
103 return error;
104 }
105
snapshot_release(struct inode * inode,struct file * filp)106 static int snapshot_release(struct inode *inode, struct file *filp)
107 {
108 struct snapshot_data *data;
109
110 lock_system_sleep();
111
112 swsusp_free();
113 data = filp->private_data;
114 data->dev = 0;
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 hibernate_release();
126
127 unlock_system_sleep();
128
129 return 0;
130 }
131
snapshot_read(struct file * filp,char __user * buf,size_t count,loff_t * offp)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
snapshot_write(struct file * filp,const char __user * buf,size_t count,loff_t * offp)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 if (need_wait) {
173 wait_for_device_probe();
174 need_wait = false;
175 }
176
177 lock_system_sleep();
178
179 data = filp->private_data;
180
181 if (!pg_offp) {
182 res = snapshot_write_next(&data->handle);
183 if (res <= 0)
184 goto unlock;
185 } else {
186 res = PAGE_SIZE - pg_offp;
187 }
188
189 if (!data_of(data->handle)) {
190 res = -EINVAL;
191 goto unlock;
192 }
193
194 res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
195 buf, count);
196 if (res > 0)
197 *offp += res;
198 unlock:
199 unlock_system_sleep();
200
201 return res;
202 }
203
204 struct compat_resume_swap_area {
205 compat_loff_t offset;
206 u32 dev;
207 } __packed;
208
snapshot_set_swap_area(struct snapshot_data * data,void __user * argp)209 static int snapshot_set_swap_area(struct snapshot_data *data,
210 void __user *argp)
211 {
212 sector_t offset;
213 dev_t swdev;
214
215 if (swsusp_swap_in_use())
216 return -EPERM;
217
218 if (in_compat_syscall()) {
219 struct compat_resume_swap_area swap_area;
220
221 if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
222 return -EFAULT;
223 swdev = new_decode_dev(swap_area.dev);
224 offset = swap_area.offset;
225 } else {
226 struct 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 }
233
234 /*
235 * User space encodes device types as two-byte values,
236 * so we need to recode them
237 */
238 data->swap = swap_type_of(swdev, offset);
239 if (data->swap < 0)
240 return swdev ? -ENODEV : -EINVAL;
241 data->dev = swdev;
242 return 0;
243 }
244
snapshot_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)245 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
246 unsigned long arg)
247 {
248 int error = 0;
249 struct snapshot_data *data;
250 loff_t size;
251 sector_t offset;
252
253 if (need_wait) {
254 wait_for_device_probe();
255 need_wait = false;
256 }
257
258 if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
259 return -ENOTTY;
260 if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
261 return -ENOTTY;
262 if (!capable(CAP_SYS_ADMIN))
263 return -EPERM;
264
265 if (!mutex_trylock(&system_transition_mutex))
266 return -EBUSY;
267
268 lock_device_hotplug();
269 data = filp->private_data;
270
271 switch (cmd) {
272
273 case SNAPSHOT_FREEZE:
274 if (data->frozen)
275 break;
276
277 ksys_sync_helper();
278
279 error = freeze_processes();
280 if (error)
281 break;
282
283 error = create_basic_memory_bitmaps();
284 if (error)
285 thaw_processes();
286 else
287 data->frozen = true;
288
289 break;
290
291 case SNAPSHOT_UNFREEZE:
292 if (!data->frozen || data->ready)
293 break;
294 pm_restore_gfp_mask();
295 free_basic_memory_bitmaps();
296 data->free_bitmaps = false;
297 thaw_processes();
298 data->frozen = false;
299 break;
300
301 case SNAPSHOT_CREATE_IMAGE:
302 if (data->mode != O_RDONLY || !data->frozen || data->ready) {
303 error = -EPERM;
304 break;
305 }
306 pm_restore_gfp_mask();
307 error = hibernation_snapshot(data->platform_support);
308 if (!error) {
309 error = put_user(in_suspend, (int __user *)arg);
310 data->ready = !freezer_test_done && !error;
311 freezer_test_done = false;
312 }
313 break;
314
315 case SNAPSHOT_ATOMIC_RESTORE:
316 snapshot_write_finalize(&data->handle);
317 if (data->mode != O_WRONLY || !data->frozen ||
318 !snapshot_image_loaded(&data->handle)) {
319 error = -EPERM;
320 break;
321 }
322 error = hibernation_restore(data->platform_support);
323 break;
324
325 case SNAPSHOT_FREE:
326 swsusp_free();
327 memset(&data->handle, 0, sizeof(struct snapshot_handle));
328 data->ready = false;
329 /*
330 * It is necessary to thaw kernel threads here, because
331 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
332 * SNAPSHOT_FREE. In that case, if kernel threads were not
333 * thawed, the preallocation of memory carried out by
334 * hibernation_snapshot() might run into problems (i.e. it
335 * might fail or even deadlock).
336 */
337 thaw_kernel_threads();
338 break;
339
340 case SNAPSHOT_PREF_IMAGE_SIZE:
341 image_size = arg;
342 break;
343
344 case SNAPSHOT_GET_IMAGE_SIZE:
345 if (!data->ready) {
346 error = -ENODATA;
347 break;
348 }
349 size = snapshot_get_image_size();
350 size <<= PAGE_SHIFT;
351 error = put_user(size, (loff_t __user *)arg);
352 break;
353
354 case SNAPSHOT_AVAIL_SWAP_SIZE:
355 size = count_swap_pages(data->swap, 1);
356 size <<= PAGE_SHIFT;
357 error = put_user(size, (loff_t __user *)arg);
358 break;
359
360 case SNAPSHOT_ALLOC_SWAP_PAGE:
361 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
362 error = -ENODEV;
363 break;
364 }
365 offset = alloc_swapdev_block(data->swap);
366 if (offset) {
367 offset <<= PAGE_SHIFT;
368 error = put_user(offset, (loff_t __user *)arg);
369 } else {
370 error = -ENOSPC;
371 }
372 break;
373
374 case SNAPSHOT_FREE_SWAP_PAGES:
375 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
376 error = -ENODEV;
377 break;
378 }
379 free_all_swap_pages(data->swap);
380 break;
381
382 case SNAPSHOT_S2RAM:
383 if (!data->frozen) {
384 error = -EPERM;
385 break;
386 }
387 /*
388 * Tasks are frozen and the notifiers have been called with
389 * PM_HIBERNATION_PREPARE
390 */
391 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
392 data->ready = false;
393 break;
394
395 case SNAPSHOT_PLATFORM_SUPPORT:
396 data->platform_support = !!arg;
397 break;
398
399 case SNAPSHOT_POWER_OFF:
400 if (data->platform_support)
401 error = hibernation_platform_enter();
402 break;
403
404 case SNAPSHOT_SET_SWAP_AREA:
405 error = snapshot_set_swap_area(data, (void __user *)arg);
406 break;
407
408 default:
409 error = -ENOTTY;
410
411 }
412
413 unlock_device_hotplug();
414 mutex_unlock(&system_transition_mutex);
415
416 return error;
417 }
418
419 #ifdef CONFIG_COMPAT
420 static long
snapshot_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)421 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
422 {
423 BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
424
425 switch (cmd) {
426 case SNAPSHOT_GET_IMAGE_SIZE:
427 case SNAPSHOT_AVAIL_SWAP_SIZE:
428 case SNAPSHOT_ALLOC_SWAP_PAGE:
429 case SNAPSHOT_CREATE_IMAGE:
430 case SNAPSHOT_SET_SWAP_AREA:
431 return snapshot_ioctl(file, cmd,
432 (unsigned long) compat_ptr(arg));
433 default:
434 return snapshot_ioctl(file, cmd, arg);
435 }
436 }
437 #endif /* CONFIG_COMPAT */
438
439 static const struct file_operations snapshot_fops = {
440 .open = snapshot_open,
441 .release = snapshot_release,
442 .read = snapshot_read,
443 .write = snapshot_write,
444 .llseek = no_llseek,
445 .unlocked_ioctl = snapshot_ioctl,
446 #ifdef CONFIG_COMPAT
447 .compat_ioctl = snapshot_compat_ioctl,
448 #endif
449 };
450
451 static struct miscdevice snapshot_device = {
452 .minor = SNAPSHOT_MINOR,
453 .name = "snapshot",
454 .fops = &snapshot_fops,
455 };
456
snapshot_device_init(void)457 static int __init snapshot_device_init(void)
458 {
459 return misc_register(&snapshot_device);
460 };
461
462 device_initcall(snapshot_device_init);
463