kernel/power/user.c

   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         char frozen;
  40         char ready;
  41         char platform_support;
  42 } snapshot_state;
  43
  44 atomic_t snapshot_device_available = ATOMIC_INIT(1);
  45
  46 static int snapshot_open(struct inode *inode, struct file *filp)
  47 {
  48         struct snapshot_data *data;
  49         int error;
  50
  51         lock_system_sleep();
  52
  53         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
  54                 error = -EBUSY;
  55                 goto Unlock;
  56         }
  57
  58         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
  59                 atomic_inc(&snapshot_device_available);
  60                 error = -ENOSYS;
  61                 goto Unlock;
  62         }
  63         if(create_basic_memory_bitmaps()) {
  64                 atomic_inc(&snapshot_device_available);
  65                 error = -ENOMEM;
  66                 goto Unlock;
  67         }
  68         nonseekable_open(inode, filp);
  69         data = &snapshot_state;
  70         filp->private_data = data;
  71         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  72         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  73                 /* Hibernating.  The image device should be accessible. */
  74                 data->swap = swsusp_resume_device ?
  75                         swap_type_of(swsusp_resume_device, 0, NULL) : -1;
  76                 data->mode = O_RDONLY;
  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                         pm_notifier_call_chain(PM_POST_RESTORE);
  92         }
  93         if (error) {
  94                 free_basic_memory_bitmaps();
  95                 atomic_inc(&snapshot_device_available);
  96         }
  97         data->frozen = 0;
  98         data->ready = 0;
  99         data->platform_support = 0;
 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         free_basic_memory_bitmaps();
 115         data = filp->private_data;
 116         free_all_swap_pages(data->swap);
 117         if (data->frozen) {
 118                 pm_restore_gfp_mask();
 119                 thaw_processes();
 120         }
 121         pm_notifier_call_chain(data->mode == O_RDONLY ?
 122                         PM_POST_HIBERNATION : PM_POST_RESTORE);
 123         atomic_inc(&snapshot_device_available);
 124
 125         unlock_system_sleep();
 126
 127         return 0;
 128 }
 129
 130 static ssize_t snapshot_read(struct file *filp, char __user *buf,
 131                              size_t count, loff_t *offp)
 132 {
 133         struct snapshot_data *data;
 134         ssize_t res;
 135         loff_t pg_offp = *offp & ~PAGE_MASK;
 136
 137         lock_system_sleep();
 138
 139         data = filp->private_data;
 140         if (!data->ready) {
 141                 res = -ENODATA;
 142                 goto Unlock;
 143         }
 144         if (!pg_offp) { /* on page boundary? */
 145                 res = snapshot_read_next(&data->handle);
 146                 if (res <= 0)
 147                         goto Unlock;
 148         } else {
 149                 res = PAGE_SIZE - pg_offp;
 150         }
 151
 152         res = simple_read_from_buffer(buf, count, &pg_offp,
 153                         data_of(data->handle), res);
 154         if (res > 0)
 155                 *offp += res;
 156
 157  Unlock:
 158         unlock_system_sleep();
 159
 160         return res;
 161 }
 162
 163 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 164                               size_t count, loff_t *offp)
 165 {
 166         struct snapshot_data *data;
 167         ssize_t res;
 168         loff_t pg_offp = *offp & ~PAGE_MASK;
 169
 170         lock_system_sleep();
 171
 172         data = filp->private_data;
 173
 174         if (!pg_offp) {
 175                 res = snapshot_write_next(&data->handle);
 176                 if (res <= 0)
 177                         goto unlock;
 178         } else {
 179                 res = PAGE_SIZE - pg_offp;
 180         }
 181
 182         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
 183                         buf, count);
 184         if (res > 0)
 185                 *offp += res;
 186 unlock:
 187         unlock_system_sleep();
 188
 189         return res;
 190 }
 191
 192 static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 193                                                         unsigned long arg)
 194 {
 195         int error = 0;
 196         struct snapshot_data *data;
 197         loff_t size;
 198         sector_t offset;
 199
 200         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 201                 return -ENOTTY;
 202         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 203                 return -ENOTTY;
 204         if (!capable(CAP_SYS_ADMIN))
 205                 return -EPERM;
 206
 207         if (!mutex_trylock(&pm_mutex))
 208                 return -EBUSY;
 209
 210         data = filp->private_data;
 211
 212         switch (cmd) {
 213
 214         case SNAPSHOT_FREEZE:
 215                 if (data->frozen)
 216                         break;
 217
 218                 printk("Syncing filesystems ... ");
 219                 sys_sync();
 220                 printk("done.\n");
 221
 222                 error = freeze_processes();
 223                 if (!error)
 224                         data->frozen = 1;
 225                 break;
 226
 227         case SNAPSHOT_UNFREEZE:
 228                 if (!data->frozen || data->ready)
 229                         break;
 230                 pm_restore_gfp_mask();
 231                 thaw_processes();
 232                 data->frozen = 0;
 233                 break;
 234
 235         case SNAPSHOT_CREATE_IMAGE:
 236                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 237                         error = -EPERM;
 238                         break;
 239                 }
 240                 pm_restore_gfp_mask();
 241                 error = hibernation_snapshot(data->platform_support);
 242                 if (!error) {
 243                         error = put_user(in_suspend, (int __user *)arg);
 244                         data->ready = !freezer_test_done && !error;
 245                         freezer_test_done = false;
 246                 }
 247                 break;
 248
 249         case SNAPSHOT_ATOMIC_RESTORE:
 250                 snapshot_write_finalize(&data->handle);
 251                 if (data->mode != O_WRONLY || !data->frozen ||
 252                     !snapshot_image_loaded(&data->handle)) {
 253                         error = -EPERM;
 254                         break;
 255                 }
 256                 error = hibernation_restore(data->platform_support);
 257                 break;
 258
 259         case SNAPSHOT_FREE:
 260                 swsusp_free();
 261                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 262                 data->ready = 0;
 263                 /*
 264                  * It is necessary to thaw kernel threads here, because
 265                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
 266                  * SNAPSHOT_FREE.  In that case, if kernel threads were not
 267                  * thawed, the preallocation of memory carried out by
 268                  * hibernation_snapshot() might run into problems (i.e. it
 269                  * might fail or even deadlock).
 270                  */
 271                 thaw_kernel_threads();
 272                 break;
 273
 274         case SNAPSHOT_PREF_IMAGE_SIZE:
 275                 image_size = arg;
 276                 break;
 277
 278         case SNAPSHOT_GET_IMAGE_SIZE:
 279                 if (!data->ready) {
 280                         error = -ENODATA;
 281                         break;
 282                 }
 283                 size = snapshot_get_image_size();
 284                 size <<= PAGE_SHIFT;
 285                 error = put_user(size, (loff_t __user *)arg);
 286                 break;
 287
 288         case SNAPSHOT_AVAIL_SWAP_SIZE:
 289                 size = count_swap_pages(data->swap, 1);
 290                 size <<= PAGE_SHIFT;
 291                 error = put_user(size, (loff_t __user *)arg);
 292                 break;
 293
 294         case SNAPSHOT_ALLOC_SWAP_PAGE:
 295                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 296                         error = -ENODEV;
 297                         break;
 298                 }
 299                 offset = alloc_swapdev_block(data->swap);
 300                 if (offset) {
 301                         offset <<= PAGE_SHIFT;
 302                         error = put_user(offset, (loff_t __user *)arg);
 303                 } else {
 304                         error = -ENOSPC;
 305                 }
 306                 break;
 307
 308         case SNAPSHOT_FREE_SWAP_PAGES:
 309                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 310                         error = -ENODEV;
 311                         break;
 312                 }
 313                 free_all_swap_pages(data->swap);
 314                 break;
 315
 316         case SNAPSHOT_S2RAM:
 317                 if (!data->frozen) {
 318                         error = -EPERM;
 319                         break;
 320                 }
 321                 /*
 322                  * Tasks are frozen and the notifiers have been called with
 323                  * PM_HIBERNATION_PREPARE
 324                  */
 325                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
 326                 data->ready = 0;
 327                 break;
 328
 329         case SNAPSHOT_PLATFORM_SUPPORT:
 330                 data->platform_support = !!arg;
 331                 break;
 332
 333         case SNAPSHOT_POWER_OFF:
 334                 if (data->platform_support)
 335                         error = hibernation_platform_enter();
 336                 break;
 337
 338         case SNAPSHOT_SET_SWAP_AREA:
 339                 if (swsusp_swap_in_use()) {
 340                         error = -EPERM;
 341                 } else {
 342                         struct resume_swap_area swap_area;
 343                         dev_t swdev;
 344
 345                         error = copy_from_user(&swap_area, (void __user *)arg,
 346                                         sizeof(struct resume_swap_area));
 347                         if (error) {
 348                                 error = -EFAULT;
 349                                 break;
 350                         }
 351
 352                         /*
 353                          * User space encodes device types as two-byte values,
 354                          * so we need to recode them
 355                          */
 356                         swdev = new_decode_dev(swap_area.dev);
 357                         if (swdev) {
 358                                 offset = swap_area.offset;
 359                                 data->swap = swap_type_of(swdev, offset, NULL);
 360                                 if (data->swap < 0)
 361                                         error = -ENODEV;
 362                         } else {
 363                                 data->swap = -1;
 364                                 error = -EINVAL;
 365                         }
 366                 }
 367                 break;
 368
 369         default:
 370                 error = -ENOTTY;
 371
 372         }
 373
 374         mutex_unlock(&pm_mutex);
 375
 376         return error;
 377 }
 378
 379 #ifdef CONFIG_COMPAT
 380
 381 struct compat_resume_swap_area {
 382         compat_loff_t offset;
 383         u32 dev;
 384 } __packed;
 385
 386 static long
 387 snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 388 {
 389         BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
 390
 391         switch (cmd) {
 392         case SNAPSHOT_GET_IMAGE_SIZE:
 393         case SNAPSHOT_AVAIL_SWAP_SIZE:
 394         case SNAPSHOT_ALLOC_SWAP_PAGE: {
 395                 compat_loff_t __user *uoffset = compat_ptr(arg);
 396                 loff_t offset;
 397                 mm_segment_t old_fs;
 398                 int err;
 399
 400                 old_fs = get_fs();
 401                 set_fs(KERNEL_DS);
 402                 err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
 403                 set_fs(old_fs);
 404                 if (!err && put_user(offset, uoffset))
 405                         err = -EFAULT;
 406                 return err;
 407         }
 408
 409         case SNAPSHOT_CREATE_IMAGE:
 410                 return snapshot_ioctl(file, cmd,
 411                                       (unsigned long) compat_ptr(arg));
 412
 413         case SNAPSHOT_SET_SWAP_AREA: {
 414                 struct compat_resume_swap_area __user *u_swap_area =
 415                         compat_ptr(arg);
 416                 struct resume_swap_area swap_area;
 417                 mm_segment_t old_fs;
 418                 int err;
 419
 420                 err = get_user(swap_area.offset, &u_swap_area->offset);
 421                 err |= get_user(swap_area.dev, &u_swap_area->dev);
 422                 if (err)
 423                         return -EFAULT;
 424                 old_fs = get_fs();
 425                 set_fs(KERNEL_DS);
 426                 err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
 427                                      (unsigned long) &swap_area);
 428                 set_fs(old_fs);
 429                 return err;
 430         }
 431
 432         default:
 433                 return snapshot_ioctl(file, cmd, arg);
 434         }
 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
 457 static int __init snapshot_device_init(void)
 458 {
 459         return misc_register(&snapshot_device);
 460 };
 461
 462 device_initcall(snapshot_device_init);