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 #define SNAPSHOT_MINOR 231
31
32 static struct snapshot_data {
33 struct snapshot_handle handle;
34 int swap;
35 int mode;
36 bool frozen;
37 bool ready;
38 bool platform_support;
39 bool free_bitmaps;
40 } snapshot_state;
41
42 atomic_t snapshot_device_available = ATOMIC_INIT(1);
43
snapshot_open(struct inode * inode,struct file * filp)44 static int snapshot_open(struct inode *inode, struct file *filp)
45 {
46 struct snapshot_data *data;
47 int error, nr_calls = 0;
48
49 if (!hibernation_available())
50 return -EPERM;
51
52 lock_system_sleep();
53
54 if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
55 error = -EBUSY;
56 goto Unlock;
57 }
58
59 if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
60 atomic_inc(&snapshot_device_available);
61 error = -ENOSYS;
62 goto Unlock;
63 }
64 nonseekable_open(inode, filp);
65 data = &snapshot_state;
66 filp->private_data = data;
67 memset(&data->handle, 0, sizeof(struct snapshot_handle));
68 if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
69 /* Hibernating. The image device should be accessible. */
70 data->swap = swsusp_resume_device ?
71 swap_type_of(swsusp_resume_device, 0, NULL) : -1;
72 data->mode = O_RDONLY;
73 data->free_bitmaps = false;
74 error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
75 if (error)
76 __pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
77 } else {
78 /*
79 * Resuming. We may need to wait for the image device to
80 * appear.
81 */
82 wait_for_device_probe();
83
84 data->swap = -1;
85 data->mode = O_WRONLY;
86 error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
87 if (!error) {
88 error = create_basic_memory_bitmaps();
89 data->free_bitmaps = !error;
90 } else
91 nr_calls--;
92
93 if (error)
94 __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
95 }
96 if (error)
97 atomic_inc(&snapshot_device_available);
98
99 data->frozen = false;
100 data->ready = false;
101 data->platform_support = false;
102
103 Unlock:
104 unlock_system_sleep();
105
106 return error;
107 }
108
snapshot_release(struct inode * inode,struct file * filp)109 static int snapshot_release(struct inode *inode, struct file *filp)
110 {
111 struct snapshot_data *data;
112
113 lock_system_sleep();
114
115 swsusp_free();
116 data = filp->private_data;
117 free_all_swap_pages(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(data->mode == O_RDONLY ?
126 PM_POST_HIBERNATION : PM_POST_RESTORE);
127 atomic_inc(&snapshot_device_available);
128
129 unlock_system_sleep();
130
131 return 0;
132 }
133
snapshot_read(struct file * filp,char __user * buf,size_t count,loff_t * offp)134 static ssize_t snapshot_read(struct file *filp, char __user *buf,
135 size_t count, loff_t *offp)
136 {
137 struct snapshot_data *data;
138 ssize_t res;
139 loff_t pg_offp = *offp & ~PAGE_MASK;
140
141 lock_system_sleep();
142
143 data = filp->private_data;
144 if (!data->ready) {
145 res = -ENODATA;
146 goto Unlock;
147 }
148 if (!pg_offp) { /* on page boundary? */
149 res = snapshot_read_next(&data->handle);
150 if (res <= 0)
151 goto Unlock;
152 } else {
153 res = PAGE_SIZE - pg_offp;
154 }
155
156 res = simple_read_from_buffer(buf, count, &pg_offp,
157 data_of(data->handle), res);
158 if (res > 0)
159 *offp += res;
160
161 Unlock:
162 unlock_system_sleep();
163
164 return res;
165 }
166
snapshot_write(struct file * filp,const char __user * buf,size_t count,loff_t * offp)167 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
168 size_t count, loff_t *offp)
169 {
170 struct snapshot_data *data;
171 ssize_t res;
172 loff_t pg_offp = *offp & ~PAGE_MASK;
173
174 lock_system_sleep();
175
176 data = filp->private_data;
177
178 if (!pg_offp) {
179 res = snapshot_write_next(&data->handle);
180 if (res <= 0)
181 goto unlock;
182 } else {
183 res = PAGE_SIZE - pg_offp;
184 }
185
186 if (!data_of(data->handle)) {
187 res = -EINVAL;
188 goto unlock;
189 }
190
191 res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
192 buf, count);
193 if (res > 0)
194 *offp += res;
195 unlock:
196 unlock_system_sleep();
197
198 return res;
199 }
200
snapshot_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)201 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
202 unsigned long arg)
203 {
204 int error = 0;
205 struct snapshot_data *data;
206 loff_t size;
207 sector_t offset;
208
209 if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
210 return -ENOTTY;
211 if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
212 return -ENOTTY;
213 if (!capable(CAP_SYS_ADMIN))
214 return -EPERM;
215
216 if (!mutex_trylock(&system_transition_mutex))
217 return -EBUSY;
218
219 lock_device_hotplug();
220 data = filp->private_data;
221
222 switch (cmd) {
223
224 case SNAPSHOT_FREEZE:
225 if (data->frozen)
226 break;
227
228 ksys_sync_helper();
229
230 error = freeze_processes();
231 if (error)
232 break;
233
234 error = create_basic_memory_bitmaps();
235 if (error)
236 thaw_processes();
237 else
238 data->frozen = true;
239
240 break;
241
242 case SNAPSHOT_UNFREEZE:
243 if (!data->frozen || data->ready)
244 break;
245 pm_restore_gfp_mask();
246 free_basic_memory_bitmaps();
247 data->free_bitmaps = false;
248 thaw_processes();
249 data->frozen = false;
250 break;
251
252 case SNAPSHOT_CREATE_IMAGE:
253 if (data->mode != O_RDONLY || !data->frozen || data->ready) {
254 error = -EPERM;
255 break;
256 }
257 pm_restore_gfp_mask();
258 error = hibernation_snapshot(data->platform_support);
259 if (!error) {
260 error = put_user(in_suspend, (int __user *)arg);
261 data->ready = !freezer_test_done && !error;
262 freezer_test_done = false;
263 }
264 break;
265
266 case SNAPSHOT_ATOMIC_RESTORE:
267 snapshot_write_finalize(&data->handle);
268 if (data->mode != O_WRONLY || !data->frozen ||
269 !snapshot_image_loaded(&data->handle)) {
270 error = -EPERM;
271 break;
272 }
273 error = hibernation_restore(data->platform_support);
274 break;
275
276 case SNAPSHOT_FREE:
277 swsusp_free();
278 memset(&data->handle, 0, sizeof(struct snapshot_handle));
279 data->ready = false;
280 /*
281 * It is necessary to thaw kernel threads here, because
282 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
283 * SNAPSHOT_FREE. In that case, if kernel threads were not
284 * thawed, the preallocation of memory carried out by
285 * hibernation_snapshot() might run into problems (i.e. it
286 * might fail or even deadlock).
287 */
288 thaw_kernel_threads();
289 break;
290
291 case SNAPSHOT_PREF_IMAGE_SIZE:
292 image_size = arg;
293 break;
294
295 case SNAPSHOT_GET_IMAGE_SIZE:
296 if (!data->ready) {
297 error = -ENODATA;
298 break;
299 }
300 size = snapshot_get_image_size();
301 size <<= PAGE_SHIFT;
302 error = put_user(size, (loff_t __user *)arg);
303 break;
304
305 case SNAPSHOT_AVAIL_SWAP_SIZE:
306 size = count_swap_pages(data->swap, 1);
307 size <<= PAGE_SHIFT;
308 error = put_user(size, (loff_t __user *)arg);
309 break;
310
311 case SNAPSHOT_ALLOC_SWAP_PAGE:
312 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
313 error = -ENODEV;
314 break;
315 }
316 offset = alloc_swapdev_block(data->swap);
317 if (offset) {
318 offset <<= PAGE_SHIFT;
319 error = put_user(offset, (loff_t __user *)arg);
320 } else {
321 error = -ENOSPC;
322 }
323 break;
324
325 case SNAPSHOT_FREE_SWAP_PAGES:
326 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
327 error = -ENODEV;
328 break;
329 }
330 free_all_swap_pages(data->swap);
331 break;
332
333 case SNAPSHOT_S2RAM:
334 if (!data->frozen) {
335 error = -EPERM;
336 break;
337 }
338 /*
339 * Tasks are frozen and the notifiers have been called with
340 * PM_HIBERNATION_PREPARE
341 */
342 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
343 data->ready = false;
344 break;
345
346 case SNAPSHOT_PLATFORM_SUPPORT:
347 data->platform_support = !!arg;
348 break;
349
350 case SNAPSHOT_POWER_OFF:
351 if (data->platform_support)
352 error = hibernation_platform_enter();
353 break;
354
355 case SNAPSHOT_SET_SWAP_AREA:
356 if (swsusp_swap_in_use()) {
357 error = -EPERM;
358 } else {
359 struct resume_swap_area swap_area;
360 dev_t swdev;
361
362 error = copy_from_user(&swap_area, (void __user *)arg,
363 sizeof(struct resume_swap_area));
364 if (error) {
365 error = -EFAULT;
366 break;
367 }
368
369 /*
370 * User space encodes device types as two-byte values,
371 * so we need to recode them
372 */
373 swdev = new_decode_dev(swap_area.dev);
374 if (swdev) {
375 offset = swap_area.offset;
376 data->swap = swap_type_of(swdev, offset, NULL);
377 if (data->swap < 0)
378 error = -ENODEV;
379 } else {
380 data->swap = -1;
381 error = -EINVAL;
382 }
383 }
384 break;
385
386 default:
387 error = -ENOTTY;
388
389 }
390
391 unlock_device_hotplug();
392 mutex_unlock(&system_transition_mutex);
393
394 return error;
395 }
396
397 #ifdef CONFIG_COMPAT
398
399 struct compat_resume_swap_area {
400 compat_loff_t offset;
401 u32 dev;
402 } __packed;
403
404 static long
snapshot_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)405 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
406 {
407 BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
408
409 switch (cmd) {
410 case SNAPSHOT_GET_IMAGE_SIZE:
411 case SNAPSHOT_AVAIL_SWAP_SIZE:
412 case SNAPSHOT_ALLOC_SWAP_PAGE: {
413 compat_loff_t __user *uoffset = compat_ptr(arg);
414 loff_t offset;
415 mm_segment_t old_fs;
416 int err;
417
418 old_fs = get_fs();
419 set_fs(KERNEL_DS);
420 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
421 set_fs(old_fs);
422 if (!err && put_user(offset, uoffset))
423 err = -EFAULT;
424 return err;
425 }
426
427 case SNAPSHOT_CREATE_IMAGE:
428 return snapshot_ioctl(file, cmd,
429 (unsigned long) compat_ptr(arg));
430
431 case SNAPSHOT_SET_SWAP_AREA: {
432 struct compat_resume_swap_area __user *u_swap_area =
433 compat_ptr(arg);
434 struct resume_swap_area swap_area;
435 mm_segment_t old_fs;
436 int err;
437
438 err = get_user(swap_area.offset, &u_swap_area->offset);
439 err |= get_user(swap_area.dev, &u_swap_area->dev);
440 if (err)
441 return -EFAULT;
442 old_fs = get_fs();
443 set_fs(KERNEL_DS);
444 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
445 (unsigned long) &swap_area);
446 set_fs(old_fs);
447 return err;
448 }
449
450 default:
451 return snapshot_ioctl(file, cmd, arg);
452 }
453 }
454
455 #endif /* CONFIG_COMPAT */
456
457 static const struct file_operations snapshot_fops = {
458 .open = snapshot_open,
459 .release = snapshot_release,
460 .read = snapshot_read,
461 .write = snapshot_write,
462 .llseek = no_llseek,
463 .unlocked_ioctl = snapshot_ioctl,
464 #ifdef CONFIG_COMPAT
465 .compat_ioctl = snapshot_compat_ioctl,
466 #endif
467 };
468
469 static struct miscdevice snapshot_device = {
470 .minor = SNAPSHOT_MINOR,
471 .name = "snapshot",
472 .fops = &snapshot_fops,
473 };
474
snapshot_device_init(void)475 static int __init snapshot_device_init(void)
476 {
477 return misc_register(&snapshot_device);
478 };
479
480 device_initcall(snapshot_device_init);
481
