linux/kernel/power/user.c
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   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        char frozen;
  40        char ready;
  41        char platform_support;
  42} snapshot_state;
  43
  44atomic_t snapshot_device_available = ATOMIC_INIT(1);
  45
  46static 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
 107static 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
 130static 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
 163static 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;
 186unlock:
 187        unlock_system_sleep();
 188
 189        return res;
 190}
 191
 192static 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
 381struct compat_resume_swap_area {
 382        compat_loff_t offset;
 383        u32 dev;
 384} __packed;
 385
 386static long
 387snapshot_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
 439static 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
 451static struct miscdevice snapshot_device = {
 452        .minor = SNAPSHOT_MINOR,
 453        .name = "snapshot",
 454        .fops = &snapshot_fops,
 455};
 456
 457static int __init snapshot_device_init(void)
 458{
 459        return misc_register(&snapshot_device);
 460};
 461
 462device_initcall(snapshot_device_init);
 463
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