xref: /openbmc/linux/kernel/power/user.c (revision bc000245) 
1 /*
2  * linux/kernel/power/user.c
3  *
4  * This file provides the user space interface for software suspend/resume.
5  *
6  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
7  *
8  * This file is released under the GPLv2.
9  *
10  */
11 
12 #include <linux/suspend.h>
13 #include <linux/syscalls.h>
14 #include <linux/reboot.h>
15 #include <linux/string.h>
16 #include <linux/device.h>
17 #include <linux/miscdevice.h>
18 #include <linux/mm.h>
19 #include <linux/swap.h>
20 #include <linux/swapops.h>
21 #include <linux/pm.h>
22 #include <linux/fs.h>
23 #include <linux/compat.h>
24 #include <linux/console.h>
25 #include <linux/cpu.h>
26 #include <linux/freezer.h>
27 
28 #include <asm/uaccess.h>
29 
30 #include "power.h"
31 
32 
33 #define SNAPSHOT_MINOR	231
34 
35 static struct snapshot_data {
36 	struct snapshot_handle handle;
37 	int swap;
38 	int mode;
39 	bool frozen;
40 	bool ready;
41 	bool platform_support;
42 	bool free_bitmaps;
43 } snapshot_state;
44 
45 atomic_t snapshot_device_available = ATOMIC_INIT(1);
46 
47 static int snapshot_open(struct inode *inode, struct file *filp)
48 {
49 	struct snapshot_data *data;
50 	int error;
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);
75 		if (error)
76 			pm_notifier_call_chain(PM_POST_HIBERNATION);
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);
87 		if (!error) {
88 			error = create_basic_memory_bitmaps();
89 			data->free_bitmaps = !error;
90 		}
91 		if (error)
92 			pm_notifier_call_chain(PM_POST_RESTORE);
93 	}
94 	if (error)
95 		atomic_inc(&snapshot_device_available);
96 
97 	data->frozen = false;
98 	data->ready = false;
99 	data->platform_support = false;
100 
101  Unlock:
102 	unlock_system_sleep();
103 
104 	return error;
105 }
106 
107 static int snapshot_release(struct inode *inode, struct file *filp)
108 {
109 	struct snapshot_data *data;
110 
111 	lock_system_sleep();
112 
113 	swsusp_free();
114 	data = filp->private_data;
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 	atomic_inc(&snapshot_device_available);
126 
127 	unlock_system_sleep();
128 
129 	return 0;
130 }
131 
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 
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 	lock_system_sleep();
173 
174 	data = filp->private_data;
175 
176 	if (!pg_offp) {
177 		res = snapshot_write_next(&data->handle);
178 		if (res <= 0)
179 			goto unlock;
180 	} else {
181 		res = PAGE_SIZE - pg_offp;
182 	}
183 
184 	res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
185 			buf, count);
186 	if (res > 0)
187 		*offp += res;
188 unlock:
189 	unlock_system_sleep();
190 
191 	return res;
192 }
193 
194 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
195 							unsigned long arg)
196 {
197 	int error = 0;
198 	struct snapshot_data *data;
199 	loff_t size;
200 	sector_t offset;
201 
202 	if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
203 		return -ENOTTY;
204 	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
205 		return -ENOTTY;
206 	if (!capable(CAP_SYS_ADMIN))
207 		return -EPERM;
208 
209 	if (!mutex_trylock(&pm_mutex))
210 		return -EBUSY;
211 
212 	lock_device_hotplug();
213 	data = filp->private_data;
214 
215 	switch (cmd) {
216 
217 	case SNAPSHOT_FREEZE:
218 		if (data->frozen)
219 			break;
220 
221 		printk("Syncing filesystems ... ");
222 		sys_sync();
223 		printk("done.\n");
224 
225 		error = freeze_processes();
226 		if (error)
227 			break;
228 
229 		error = create_basic_memory_bitmaps();
230 		if (error)
231 			thaw_processes();
232 		else
233 			data->frozen = true;
234 
235 		break;
236 
237 	case SNAPSHOT_UNFREEZE:
238 		if (!data->frozen || data->ready)
239 			break;
240 		pm_restore_gfp_mask();
241 		free_basic_memory_bitmaps();
242 		data->free_bitmaps = false;
243 		thaw_processes();
244 		data->frozen = false;
245 		break;
246 
247 	case SNAPSHOT_CREATE_IMAGE:
248 		if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
249 			error = -EPERM;
250 			break;
251 		}
252 		pm_restore_gfp_mask();
253 		error = hibernation_snapshot(data->platform_support);
254 		if (!error) {
255 			error = put_user(in_suspend, (int __user *)arg);
256 			data->ready = !freezer_test_done && !error;
257 			freezer_test_done = false;
258 		}
259 		break;
260 
261 	case SNAPSHOT_ATOMIC_RESTORE:
262 		snapshot_write_finalize(&data->handle);
263 		if (data->mode != O_WRONLY || !data->frozen ||
264 		    !snapshot_image_loaded(&data->handle)) {
265 			error = -EPERM;
266 			break;
267 		}
268 		error = hibernation_restore(data->platform_support);
269 		break;
270 
271 	case SNAPSHOT_FREE:
272 		swsusp_free();
273 		memset(&data->handle, 0, sizeof(struct snapshot_handle));
274 		data->ready = false;
275 		/*
276 		 * It is necessary to thaw kernel threads here, because
277 		 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
278 		 * SNAPSHOT_FREE.  In that case, if kernel threads were not
279 		 * thawed, the preallocation of memory carried out by
280 		 * hibernation_snapshot() might run into problems (i.e. it
281 		 * might fail or even deadlock).
282 		 */
283 		thaw_kernel_threads();
284 		break;
285 
286 	case SNAPSHOT_PREF_IMAGE_SIZE:
287 		image_size = arg;
288 		break;
289 
290 	case SNAPSHOT_GET_IMAGE_SIZE:
291 		if (!data->ready) {
292 			error = -ENODATA;
293 			break;
294 		}
295 		size = snapshot_get_image_size();
296 		size <<= PAGE_SHIFT;
297 		error = put_user(size, (loff_t __user *)arg);
298 		break;
299 
300 	case SNAPSHOT_AVAIL_SWAP_SIZE:
301 		size = count_swap_pages(data->swap, 1);
302 		size <<= PAGE_SHIFT;
303 		error = put_user(size, (loff_t __user *)arg);
304 		break;
305 
306 	case SNAPSHOT_ALLOC_SWAP_PAGE:
307 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
308 			error = -ENODEV;
309 			break;
310 		}
311 		offset = alloc_swapdev_block(data->swap);
312 		if (offset) {
313 			offset <<= PAGE_SHIFT;
314 			error = put_user(offset, (loff_t __user *)arg);
315 		} else {
316 			error = -ENOSPC;
317 		}
318 		break;
319 
320 	case SNAPSHOT_FREE_SWAP_PAGES:
321 		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
322 			error = -ENODEV;
323 			break;
324 		}
325 		free_all_swap_pages(data->swap);
326 		break;
327 
328 	case SNAPSHOT_S2RAM:
329 		if (!data->frozen) {
330 			error = -EPERM;
331 			break;
332 		}
333 		/*
334 		 * Tasks are frozen and the notifiers have been called with
335 		 * PM_HIBERNATION_PREPARE
336 		 */
337 		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
338 		data->ready = false;
339 		break;
340 
341 	case SNAPSHOT_PLATFORM_SUPPORT:
342 		data->platform_support = !!arg;
343 		break;
344 
345 	case SNAPSHOT_POWER_OFF:
346 		if (data->platform_support)
347 			error = hibernation_platform_enter();
348 		break;
349 
350 	case SNAPSHOT_SET_SWAP_AREA:
351 		if (swsusp_swap_in_use()) {
352 			error = -EPERM;
353 		} else {
354 			struct resume_swap_area swap_area;
355 			dev_t swdev;
356 
357 			error = copy_from_user(&swap_area, (void __user *)arg,
358 					sizeof(struct resume_swap_area));
359 			if (error) {
360 				error = -EFAULT;
361 				break;
362 			}
363 
364 			/*
365 			 * User space encodes device types as two-byte values,
366 			 * so we need to recode them
367 			 */
368 			swdev = new_decode_dev(swap_area.dev);
369 			if (swdev) {
370 				offset = swap_area.offset;
371 				data->swap = swap_type_of(swdev, offset, NULL);
372 				if (data->swap < 0)
373 					error = -ENODEV;
374 			} else {
375 				data->swap = -1;
376 				error = -EINVAL;
377 			}
378 		}
379 		break;
380 
381 	default:
382 		error = -ENOTTY;
383 
384 	}
385 
386 	unlock_device_hotplug();
387 	mutex_unlock(&pm_mutex);
388 
389 	return error;
390 }
391 
392 #ifdef CONFIG_COMPAT
393 
394 struct compat_resume_swap_area {
395 	compat_loff_t offset;
396 	u32 dev;
397 } __packed;
398 
399 static long
400 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
401 {
402 	BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
403 
404 	switch (cmd) {
405 	case SNAPSHOT_GET_IMAGE_SIZE:
406 	case SNAPSHOT_AVAIL_SWAP_SIZE:
407 	case SNAPSHOT_ALLOC_SWAP_PAGE: {
408 		compat_loff_t __user *uoffset = compat_ptr(arg);
409 		loff_t offset;
410 		mm_segment_t old_fs;
411 		int err;
412 
413 		old_fs = get_fs();
414 		set_fs(KERNEL_DS);
415 		err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
416 		set_fs(old_fs);
417 		if (!err && put_user(offset, uoffset))
418 			err = -EFAULT;
419 		return err;
420 	}
421 
422 	case SNAPSHOT_CREATE_IMAGE:
423 		return snapshot_ioctl(file, cmd,
424 				      (unsigned long) compat_ptr(arg));
425 
426 	case SNAPSHOT_SET_SWAP_AREA: {
427 		struct compat_resume_swap_area __user *u_swap_area =
428 			compat_ptr(arg);
429 		struct resume_swap_area swap_area;
430 		mm_segment_t old_fs;
431 		int err;
432 
433 		err = get_user(swap_area.offset, &u_swap_area->offset);
434 		err |= get_user(swap_area.dev, &u_swap_area->dev);
435 		if (err)
436 			return -EFAULT;
437 		old_fs = get_fs();
438 		set_fs(KERNEL_DS);
439 		err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
440 				     (unsigned long) &swap_area);
441 		set_fs(old_fs);
442 		return err;
443 	}
444 
445 	default:
446 		return snapshot_ioctl(file, cmd, arg);
447 	}
448 }
449 
450 #endif /* CONFIG_COMPAT */
451 
452 static const struct file_operations snapshot_fops = {
453 	.open = snapshot_open,
454 	.release = snapshot_release,
455 	.read = snapshot_read,
456 	.write = snapshot_write,
457 	.llseek = no_llseek,
458 	.unlocked_ioctl = snapshot_ioctl,
459 #ifdef CONFIG_COMPAT
460 	.compat_ioctl = snapshot_compat_ioctl,
461 #endif
462 };
463 
464 static struct miscdevice snapshot_device = {
465 	.minor = SNAPSHOT_MINOR,
466 	.name = "snapshot",
467 	.fops = &snapshot_fops,
468 };
469 
470 static int __init snapshot_device_init(void)
471 {
472 	return misc_register(&snapshot_device);
473 };
474 
475 device_initcall(snapshot_device_init);
476