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
35static 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
45atomic_t snapshot_device_available = ATOMIC_INIT(1);
46
47static 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 (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
58		error = -EBUSY;
59		goto Unlock;
60	}
61
62	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
63		atomic_inc(&snapshot_device_available);
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 = swsusp_resume_device ?
74			swap_type_of(swsusp_resume_device, 0, NULL) : -1;
75		data->mode = O_RDONLY;
76		data->free_bitmaps = false;
77		error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
78		if (error)
79			pm_notifier_call_chain(PM_POST_HIBERNATION);
80	} else {
81		/*
82		 * Resuming.  We may need to wait for the image device to
83		 * appear.
84		 */
85		wait_for_device_probe();
86
87		data->swap = -1;
88		data->mode = O_WRONLY;
89		error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
90		if (!error) {
91			error = create_basic_memory_bitmaps();
92			data->free_bitmaps = !error;
93		}
94		if (error)
95			pm_notifier_call_chain(PM_POST_RESTORE);
96	}
97	if (error)
98		atomic_inc(&snapshot_device_available);
99
100	data->frozen = false;
101	data->ready = false;
102	data->platform_support = false;
103
104 Unlock:
105	unlock_system_sleep();
106
107	return error;
108}
109
110static int snapshot_release(struct inode *inode, struct file *filp)
111{
112	struct snapshot_data *data;
113
114	lock_system_sleep();
115
116	swsusp_free();
117	data = filp->private_data;
118	free_all_swap_pages(data->swap);
119	if (data->frozen) {
120		pm_restore_gfp_mask();
121		free_basic_memory_bitmaps();
122		thaw_processes();
123	} else if (data->free_bitmaps) {
124		free_basic_memory_bitmaps();
125	}
126	pm_notifier_call_chain(data->mode == O_RDONLY ?
127			PM_POST_HIBERNATION : PM_POST_RESTORE);
128	atomic_inc(&snapshot_device_available);
129
130	unlock_system_sleep();
131
132	return 0;
133}
134
135static ssize_t snapshot_read(struct file *filp, char __user *buf,
136                             size_t count, loff_t *offp)
137{
138	struct snapshot_data *data;
139	ssize_t res;
140	loff_t pg_offp = *offp & ~PAGE_MASK;
141
142	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(&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(buf, count, &pg_offp,
158			data_of(data->handle), res);
159	if (res > 0)
160		*offp += res;
161
162 Unlock:
163	unlock_system_sleep();
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	struct snapshot_data *data;
172	ssize_t res;
173	loff_t pg_offp = *offp & ~PAGE_MASK;
174
175	lock_system_sleep();
176
177	data = filp->private_data;
178
179	if (!pg_offp) {
180		res = snapshot_write_next(&data->handle);
181		if (res <= 0)
182			goto unlock;
183	} else {
184		res = PAGE_SIZE - pg_offp;
185	}
186
187	res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
188			buf, count);
189	if (res > 0)
190		*offp += res;
191unlock:
192	unlock_system_sleep();
193
194	return res;
195}
196
197static long snapshot_ioctl(struct file *filp, unsigned int cmd,
198							unsigned long arg)
199{
200	int error = 0;
201	struct snapshot_data *data;
202	loff_t size;
203	sector_t offset;
204
205	if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
206		return -ENOTTY;
207	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
208		return -ENOTTY;
209	if (!capable(CAP_SYS_ADMIN))
210		return -EPERM;
211
212	if (!mutex_trylock(&pm_mutex))
213		return -EBUSY;
214
215	lock_device_hotplug();
216	data = filp->private_data;
217
218	switch (cmd) {
219
220	case SNAPSHOT_FREEZE:
221		if (data->frozen)
222			break;
223
224		printk("Syncing filesystems ... ");
225		sys_sync();
226		printk("done.\n");
227
228		error = freeze_processes();
229		if (error)
230			break;
231
232		error = create_basic_memory_bitmaps();
233		if (error)
234			thaw_processes();
235		else
236			data->frozen = true;
237
238		break;
239
240	case SNAPSHOT_UNFREEZE:
241		if (!data->frozen || data->ready)
242			break;
243		pm_restore_gfp_mask();
244		free_basic_memory_bitmaps();
245		data->free_bitmaps = false;
246		thaw_processes();
247		data->frozen = false;
248		break;
249
250	case SNAPSHOT_CREATE_IMAGE:
251		if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
252			error = -EPERM;
253			break;
254		}
255		pm_restore_gfp_mask();
256		error = hibernation_snapshot(data->platform_support);
257		if (!error) {
258			error = put_user(in_suspend, (int __user *)arg);
259			data->ready = !freezer_test_done && !error;
260			freezer_test_done = false;
261		}
262		break;
263
264	case SNAPSHOT_ATOMIC_RESTORE:
265		snapshot_write_finalize(&data->handle);
266		if (data->mode != O_WRONLY || !data->frozen ||
267		    !snapshot_image_loaded(&data->handle)) {
268			error = -EPERM;
269			break;
270		}
271		error = hibernation_restore(data->platform_support);
272		break;
273
274	case SNAPSHOT_FREE:
275		swsusp_free();
276		memset(&data->handle, 0, sizeof(struct snapshot_handle));
277		data->ready = false;
278		/*
279		 * It is necessary to thaw kernel threads here, because
280		 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
281		 * SNAPSHOT_FREE.  In that case, if kernel threads were not
282		 * thawed, the preallocation of memory carried out by
283		 * hibernation_snapshot() might run into problems (i.e. it
284		 * might fail or even deadlock).
285		 */
286		thaw_kernel_threads();
287		break;
288
289	case SNAPSHOT_PREF_IMAGE_SIZE:
290		image_size = arg;
291		break;
292
293	case SNAPSHOT_GET_IMAGE_SIZE:
294		if (!data->ready) {
295			error = -ENODATA;
296			break;
297		}
298		size = snapshot_get_image_size();
299		size <<= PAGE_SHIFT;
300		error = put_user(size, (loff_t __user *)arg);
301		break;
302
303	case SNAPSHOT_AVAIL_SWAP_SIZE:
304		size = count_swap_pages(data->swap, 1);
305		size <<= PAGE_SHIFT;
306		error = put_user(size, (loff_t __user *)arg);
307		break;
308
309	case SNAPSHOT_ALLOC_SWAP_PAGE:
310		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
311			error = -ENODEV;
312			break;
313		}
314		offset = alloc_swapdev_block(data->swap);
315		if (offset) {
316			offset <<= PAGE_SHIFT;
317			error = put_user(offset, (loff_t __user *)arg);
318		} else {
319			error = -ENOSPC;
320		}
321		break;
322
323	case SNAPSHOT_FREE_SWAP_PAGES:
324		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
325			error = -ENODEV;
326			break;
327		}
328		free_all_swap_pages(data->swap);
329		break;
330
331	case SNAPSHOT_S2RAM:
332		if (!data->frozen) {
333			error = -EPERM;
334			break;
335		}
336		/*
337		 * Tasks are frozen and the notifiers have been called with
338		 * PM_HIBERNATION_PREPARE
339		 */
340		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
341		data->ready = false;
342		break;
343
344	case SNAPSHOT_PLATFORM_SUPPORT:
345		data->platform_support = !!arg;
346		break;
347
348	case SNAPSHOT_POWER_OFF:
349		if (data->platform_support)
350			error = hibernation_platform_enter();
351		break;
352
353	case SNAPSHOT_SET_SWAP_AREA:
354		if (swsusp_swap_in_use()) {
355			error = -EPERM;
356		} else {
357			struct resume_swap_area swap_area;
358			dev_t swdev;
359
360			error = copy_from_user(&swap_area, (void __user *)arg,
361					sizeof(struct resume_swap_area));
362			if (error) {
363				error = -EFAULT;
364				break;
365			}
366
367			/*
368			 * User space encodes device types as two-byte values,
369			 * so we need to recode them
370			 */
371			swdev = new_decode_dev(swap_area.dev);
372			if (swdev) {
373				offset = swap_area.offset;
374				data->swap = swap_type_of(swdev, offset, NULL);
375				if (data->swap < 0)
376					error = -ENODEV;
377			} else {
378				data->swap = -1;
379				error = -EINVAL;
380			}
381		}
382		break;
383
384	default:
385		error = -ENOTTY;
386
387	}
388
389	unlock_device_hotplug();
390	mutex_unlock(&pm_mutex);
391
392	return error;
393}
394
395#ifdef CONFIG_COMPAT
396
397struct compat_resume_swap_area {
398	compat_loff_t offset;
399	u32 dev;
400} __packed;
401
402static long
403snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
404{
405	BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
406
407	switch (cmd) {
408	case SNAPSHOT_GET_IMAGE_SIZE:
409	case SNAPSHOT_AVAIL_SWAP_SIZE:
410	case SNAPSHOT_ALLOC_SWAP_PAGE: {
411		compat_loff_t __user *uoffset = compat_ptr(arg);
412		loff_t offset;
413		mm_segment_t old_fs;
414		int err;
415
416		old_fs = get_fs();
417		set_fs(KERNEL_DS);
418		err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
419		set_fs(old_fs);
420		if (!err && put_user(offset, uoffset))
421			err = -EFAULT;
422		return err;
423	}
424
425	case SNAPSHOT_CREATE_IMAGE:
426		return snapshot_ioctl(file, cmd,
427				      (unsigned long) compat_ptr(arg));
428
429	case SNAPSHOT_SET_SWAP_AREA: {
430		struct compat_resume_swap_area __user *u_swap_area =
431			compat_ptr(arg);
432		struct resume_swap_area swap_area;
433		mm_segment_t old_fs;
434		int err;
435
436		err = get_user(swap_area.offset, &u_swap_area->offset);
437		err |= get_user(swap_area.dev, &u_swap_area->dev);
438		if (err)
439			return -EFAULT;
440		old_fs = get_fs();
441		set_fs(KERNEL_DS);
442		err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
443				     (unsigned long) &swap_area);
444		set_fs(old_fs);
445		return err;
446	}
447
448	default:
449		return snapshot_ioctl(file, cmd, arg);
450	}
451}
452
453#endif /* CONFIG_COMPAT */
454
455static const struct file_operations snapshot_fops = {
456	.open = snapshot_open,
457	.release = snapshot_release,
458	.read = snapshot_read,
459	.write = snapshot_write,
460	.llseek = no_llseek,
461	.unlocked_ioctl = snapshot_ioctl,
462#ifdef CONFIG_COMPAT
463	.compat_ioctl = snapshot_compat_ioctl,
464#endif
465};
466
467static struct miscdevice snapshot_device = {
468	.minor = SNAPSHOT_MINOR,
469	.name = "snapshot",
470	.fops = &snapshot_fops,
471};
472
473static int __init snapshot_device_init(void)
474{
475	return misc_register(&snapshot_device);
476};
477
478device_initcall(snapshot_device_init);
479