1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/kernel/power/user.c
5 * This file provides the user space interface for software suspend/resume.
7 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
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>
16 #include <linux/swap.h>
17 #include <linux/swapops.h>
20 #include <linux/compat.h>
21 #include <linux/console.h>
22 #include <linux/cpu.h>
23 #include <linux/freezer.h>
25 #include <linux/uaccess.h>
30 static struct snapshot_data {
31 struct snapshot_handle handle;
36 bool platform_support;
40 atomic_t snapshot_device_available = ATOMIC_INIT(1);
42 static int snapshot_open(struct inode *inode, struct file *filp)
44 struct snapshot_data *data;
45 int error, nr_calls = 0;
47 if (!hibernation_available())
52 if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
57 if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
58 atomic_inc(&snapshot_device_available);
62 nonseekable_open(inode, filp);
63 data = &snapshot_state;
64 filp->private_data = data;
65 memset(&data->handle, 0, sizeof(struct snapshot_handle));
66 if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
67 /* Hibernating. The image device should be accessible. */
68 data->swap = swsusp_resume_device ?
69 swap_type_of(swsusp_resume_device, 0, NULL) : -1;
70 data->mode = O_RDONLY;
71 data->free_bitmaps = false;
72 error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
74 __pm_notifier_call_chain(PM_POST_HIBERNATION, --nr_calls, NULL);
77 * Resuming. We may need to wait for the image device to
80 wait_for_device_probe();
83 data->mode = O_WRONLY;
84 error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
86 error = create_basic_memory_bitmaps();
87 data->free_bitmaps = !error;
92 __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
95 atomic_inc(&snapshot_device_available);
99 data->platform_support = false;
102 unlock_system_sleep();
107 static int snapshot_release(struct inode *inode, struct file *filp)
109 struct snapshot_data *data;
114 data = filp->private_data;
115 free_all_swap_pages(data->swap);
117 pm_restore_gfp_mask();
118 free_basic_memory_bitmaps();
120 } else if (data->free_bitmaps) {
121 free_basic_memory_bitmaps();
123 pm_notifier_call_chain(data->mode == O_RDONLY ?
124 PM_POST_HIBERNATION : PM_POST_RESTORE);
125 atomic_inc(&snapshot_device_available);
127 unlock_system_sleep();
132 static ssize_t snapshot_read(struct file *filp, char __user *buf,
133 size_t count, loff_t *offp)
135 struct snapshot_data *data;
137 loff_t pg_offp = *offp & ~PAGE_MASK;
141 data = filp->private_data;
146 if (!pg_offp) { /* on page boundary? */
147 res = snapshot_read_next(&data->handle);
151 res = PAGE_SIZE - pg_offp;
154 res = simple_read_from_buffer(buf, count, &pg_offp,
155 data_of(data->handle), res);
160 unlock_system_sleep();
165 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
166 size_t count, loff_t *offp)
168 struct snapshot_data *data;
170 loff_t pg_offp = *offp & ~PAGE_MASK;
174 data = filp->private_data;
177 res = snapshot_write_next(&data->handle);
181 res = PAGE_SIZE - pg_offp;
184 if (!data_of(data->handle)) {
189 res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
194 unlock_system_sleep();
199 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
203 struct snapshot_data *data;
207 if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
209 if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
211 if (!capable(CAP_SYS_ADMIN))
214 if (!mutex_trylock(&system_transition_mutex))
217 lock_device_hotplug();
218 data = filp->private_data;
222 case SNAPSHOT_FREEZE:
228 error = freeze_processes();
232 error = create_basic_memory_bitmaps();
240 case SNAPSHOT_UNFREEZE:
241 if (!data->frozen || data->ready)
243 pm_restore_gfp_mask();
244 free_basic_memory_bitmaps();
245 data->free_bitmaps = false;
247 data->frozen = false;
250 case SNAPSHOT_CREATE_IMAGE:
251 if (data->mode != O_RDONLY || !data->frozen || data->ready) {
255 pm_restore_gfp_mask();
256 error = hibernation_snapshot(data->platform_support);
258 error = put_user(in_suspend, (int __user *)arg);
259 data->ready = !freezer_test_done && !error;
260 freezer_test_done = false;
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)) {
271 error = hibernation_restore(data->platform_support);
276 memset(&data->handle, 0, sizeof(struct snapshot_handle));
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).
286 thaw_kernel_threads();
289 case SNAPSHOT_PREF_IMAGE_SIZE:
293 case SNAPSHOT_GET_IMAGE_SIZE:
298 size = snapshot_get_image_size();
300 error = put_user(size, (loff_t __user *)arg);
303 case SNAPSHOT_AVAIL_SWAP_SIZE:
304 size = count_swap_pages(data->swap, 1);
306 error = put_user(size, (loff_t __user *)arg);
309 case SNAPSHOT_ALLOC_SWAP_PAGE:
310 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
314 offset = alloc_swapdev_block(data->swap);
316 offset <<= PAGE_SHIFT;
317 error = put_user(offset, (loff_t __user *)arg);
323 case SNAPSHOT_FREE_SWAP_PAGES:
324 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
328 free_all_swap_pages(data->swap);
337 * Tasks are frozen and the notifiers have been called with
338 * PM_HIBERNATION_PREPARE
340 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
344 case SNAPSHOT_PLATFORM_SUPPORT:
345 data->platform_support = !!arg;
348 case SNAPSHOT_POWER_OFF:
349 if (data->platform_support)
350 error = hibernation_platform_enter();
353 case SNAPSHOT_SET_SWAP_AREA:
354 if (swsusp_swap_in_use()) {
357 struct resume_swap_area swap_area;
360 error = copy_from_user(&swap_area, (void __user *)arg,
361 sizeof(struct resume_swap_area));
368 * User space encodes device types as two-byte values,
369 * so we need to recode them
371 swdev = new_decode_dev(swap_area.dev);
373 offset = swap_area.offset;
374 data->swap = swap_type_of(swdev, offset, NULL);
389 unlock_device_hotplug();
390 mutex_unlock(&system_transition_mutex);
397 struct compat_resume_swap_area {
398 compat_loff_t offset;
403 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
405 BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
408 case SNAPSHOT_GET_IMAGE_SIZE:
409 case SNAPSHOT_AVAIL_SWAP_SIZE:
410 case SNAPSHOT_ALLOC_SWAP_PAGE:
411 case SNAPSHOT_CREATE_IMAGE:
412 return snapshot_ioctl(file, cmd,
413 (unsigned long) compat_ptr(arg));
415 case SNAPSHOT_SET_SWAP_AREA: {
416 struct compat_resume_swap_area __user *u_swap_area =
418 struct resume_swap_area swap_area;
422 err = get_user(swap_area.offset, &u_swap_area->offset);
423 err |= get_user(swap_area.dev, &u_swap_area->dev);
428 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
429 (unsigned long) &swap_area);
435 return snapshot_ioctl(file, cmd, arg);
439 #endif /* CONFIG_COMPAT */
441 static const struct file_operations snapshot_fops = {
442 .open = snapshot_open,
443 .release = snapshot_release,
444 .read = snapshot_read,
445 .write = snapshot_write,
447 .unlocked_ioctl = snapshot_ioctl,
449 .compat_ioctl = snapshot_compat_ioctl,
453 static struct miscdevice snapshot_device = {
454 .minor = SNAPSHOT_MINOR,
456 .fops = &snapshot_fops,
459 static int __init snapshot_device_init(void)
461 return misc_register(&snapshot_device);
464 device_initcall(snapshot_device_init);