fs/pstore/platform.c

   1 /*
   2  * Persistent Storage - platform driver interface parts.
   3  *
   4  * Copyright (C) 2007-2008 Google, Inc.
   5  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #define pr_fmt(fmt) "pstore: " fmt
  22
  23 #include <linux/atomic.h>
  24 #include <linux/types.h>
  25 #include <linux/errno.h>
  26 #include <linux/init.h>
  27 #include <linux/kmsg_dump.h>
  28 #include <linux/console.h>
  29 #include <linux/module.h>
  30 #include <linux/pstore.h>
  31 #ifdef CONFIG_PSTORE_ZLIB_COMPRESS
  32 #include <linux/zlib.h>
  33 #endif
  34 #ifdef CONFIG_PSTORE_LZO_COMPRESS
  35 #include <linux/lzo.h>
  36 #endif
  37 #ifdef CONFIG_PSTORE_LZ4_COMPRESS
  38 #include <linux/lz4.h>
  39 #endif
  40 #include <linux/string.h>
  41 #include <linux/timer.h>
  42 #include <linux/slab.h>
  43 #include <linux/uaccess.h>
  44 #include <linux/hardirq.h>
  45 #include <linux/jiffies.h>
  46 #include <linux/workqueue.h>
  47
  48 #include "internal.h"
  49
  50 /*
  51  * We defer making "oops" entries appear in pstore - see
  52  * whether the system is actually still running well enough
  53  * to let someone see the entry
  54  */
  55 static int pstore_update_ms = -1;
  56 module_param_named(update_ms, pstore_update_ms, int, 0600);
  57 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
  58                  "(default is -1, which means runtime updates are disabled; "
  59                  "enabling this option is not safe, it may lead to further "
  60                  "corruption on Oopses)");
  61
  62 static int pstore_new_entry;
  63
  64 static void pstore_timefunc(struct timer_list *);
  65 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
  66
  67 static void pstore_dowork(struct work_struct *);
  68 static DECLARE_WORK(pstore_work, pstore_dowork);
  69
  70 /*
  71  * pstore_lock just protects "psinfo" during
  72  * calls to pstore_register()
  73  */
  74 static DEFINE_SPINLOCK(pstore_lock);
  75 struct pstore_info *psinfo;
  76
  77 static char *backend;
  78
  79 /* Compression parameters */
  80 #ifdef CONFIG_PSTORE_ZLIB_COMPRESS
  81 #define COMPR_LEVEL 6
  82 #define WINDOW_BITS 12
  83 #define MEM_LEVEL 4
  84 static struct z_stream_s stream;
  85 #else
  86 static unsigned char *workspace;
  87 #endif
  88
  89 struct pstore_zbackend {
  90         int (*compress)(const void *in, void *out, size_t inlen, size_t outlen);
  91         int (*decompress)(void *in, void *out, size_t inlen, size_t outlen);
  92         void (*allocate)(void);
  93         void (*free)(void);
  94
  95         const char *name;
  96 };
  97
  98 static char *big_oops_buf;
  99 static size_t big_oops_buf_sz;
 100
 101 /* How much of the console log to snapshot */
 102 unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
 103
 104 void pstore_set_kmsg_bytes(int bytes)
 105 {
 106         kmsg_bytes = bytes;
 107 }
 108
 109 /* Tag each group of saved records with a sequence number */
 110 static int      oopscount;
 111
 112 static const char *get_reason_str(enum kmsg_dump_reason reason)
 113 {
 114         switch (reason) {
 115         case KMSG_DUMP_PANIC:
 116                 return "Panic";
 117         case KMSG_DUMP_OOPS:
 118                 return "Oops";
 119         case KMSG_DUMP_EMERG:
 120                 return "Emergency";
 121         case KMSG_DUMP_RESTART:
 122                 return "Restart";
 123         case KMSG_DUMP_HALT:
 124                 return "Halt";
 125         case KMSG_DUMP_POWEROFF:
 126                 return "Poweroff";
 127         default:
 128                 return "Unknown";
 129         }
 130 }
 131
 132 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 133 {
 134         /*
 135          * In case of NMI path, pstore shouldn't be blocked
 136          * regardless of reason.
 137          */
 138         if (in_nmi())
 139                 return true;
 140
 141         switch (reason) {
 142         /* In panic case, other cpus are stopped by smp_send_stop(). */
 143         case KMSG_DUMP_PANIC:
 144         /* Emergency restart shouldn't be blocked by spin lock. */
 145         case KMSG_DUMP_EMERG:
 146                 return true;
 147         default:
 148                 return false;
 149         }
 150 }
 151 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
 152
 153 #ifdef CONFIG_PSTORE_ZLIB_COMPRESS
 154 /* Derived from logfs_compress() */
 155 static int compress_zlib(const void *in, void *out, size_t inlen, size_t outlen)
 156 {
 157         int err, ret;
 158
 159         ret = -EIO;
 160         err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
 161                                                 MEM_LEVEL, Z_DEFAULT_STRATEGY);
 162         if (err != Z_OK)
 163                 goto error;
 164
 165         stream.next_in = in;
 166         stream.avail_in = inlen;
 167         stream.total_in = 0;
 168         stream.next_out = out;
 169         stream.avail_out = outlen;
 170         stream.total_out = 0;
 171
 172         err = zlib_deflate(&stream, Z_FINISH);
 173         if (err != Z_STREAM_END)
 174                 goto error;
 175
 176         err = zlib_deflateEnd(&stream);
 177         if (err != Z_OK)
 178                 goto error;
 179
 180         if (stream.total_out >= stream.total_in)
 181                 goto error;
 182
 183         ret = stream.total_out;
 184 error:
 185         return ret;
 186 }
 187
 188 /* Derived from logfs_uncompress */
 189 static int decompress_zlib(void *in, void *out, size_t inlen, size_t outlen)
 190 {
 191         int err, ret;
 192
 193         ret = -EIO;
 194         err = zlib_inflateInit2(&stream, WINDOW_BITS);
 195         if (err != Z_OK)
 196                 goto error;
 197
 198         stream.next_in = in;
 199         stream.avail_in = inlen;
 200         stream.total_in = 0;
 201         stream.next_out = out;
 202         stream.avail_out = outlen;
 203         stream.total_out = 0;
 204
 205         err = zlib_inflate(&stream, Z_FINISH);
 206         if (err != Z_STREAM_END)
 207                 goto error;
 208
 209         err = zlib_inflateEnd(&stream);
 210         if (err != Z_OK)
 211                 goto error;
 212
 213         ret = stream.total_out;
 214 error:
 215         return ret;
 216 }
 217
 218 static void allocate_zlib(void)
 219 {
 220         size_t size;
 221         size_t cmpr;
 222
 223         switch (psinfo->bufsize) {
 224         /* buffer range for efivars */
 225         case 1000 ... 2000:
 226                 cmpr = 56;
 227                 break;
 228         case 2001 ... 3000:
 229                 cmpr = 54;
 230                 break;
 231         case 3001 ... 3999:
 232                 cmpr = 52;
 233                 break;
 234         /* buffer range for nvram, erst */
 235         case 4000 ... 10000:
 236                 cmpr = 45;
 237                 break;
 238         default:
 239                 cmpr = 60;
 240                 break;
 241         }
 242
 243         big_oops_buf_sz = (psinfo->bufsize * 100) / cmpr;
 244         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 245         if (big_oops_buf) {
 246                 size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
 247                         zlib_inflate_workspacesize());
 248                 stream.workspace = kmalloc(size, GFP_KERNEL);
 249                 if (!stream.workspace) {
 250                         pr_err("No memory for compression workspace; skipping compression\n");
 251                         kfree(big_oops_buf);
 252                         big_oops_buf = NULL;
 253                 }
 254         } else {
 255                 pr_err("No memory for uncompressed data; skipping compression\n");
 256                 stream.workspace = NULL;
 257         }
 258
 259 }
 260
 261 static void free_zlib(void)
 262 {
 263         kfree(stream.workspace);
 264         stream.workspace = NULL;
 265         kfree(big_oops_buf);
 266         big_oops_buf = NULL;
 267         big_oops_buf_sz = 0;
 268 }
 269
 270 static const struct pstore_zbackend backend_zlib = {
 271         .compress       = compress_zlib,
 272         .decompress     = decompress_zlib,
 273         .allocate       = allocate_zlib,
 274         .free           = free_zlib,
 275         .name           = "zlib",
 276 };
 277 #endif
 278
 279 #ifdef CONFIG_PSTORE_LZO_COMPRESS
 280 static int compress_lzo(const void *in, void *out, size_t inlen, size_t outlen)
 281 {
 282         int ret;
 283
 284         ret = lzo1x_1_compress(in, inlen, out, &outlen, workspace);
 285         if (ret != LZO_E_OK) {
 286                 pr_err("lzo_compress error, ret = %d!\n", ret);
 287                 return -EIO;
 288         }
 289
 290         return outlen;
 291 }
 292
 293 static int decompress_lzo(void *in, void *out, size_t inlen, size_t outlen)
 294 {
 295         int ret;
 296
 297         ret = lzo1x_decompress_safe(in, inlen, out, &outlen);
 298         if (ret != LZO_E_OK) {
 299                 pr_err("lzo_decompress error, ret = %d!\n", ret);
 300                 return -EIO;
 301         }
 302
 303         return outlen;
 304 }
 305
 306 static void allocate_lzo(void)
 307 {
 308         big_oops_buf_sz = lzo1x_worst_compress(psinfo->bufsize);
 309         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 310         if (big_oops_buf) {
 311                 workspace = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 312                 if (!workspace) {
 313                         pr_err("No memory for compression workspace; skipping compression\n");
 314                         kfree(big_oops_buf);
 315                         big_oops_buf = NULL;
 316                 }
 317         } else {
 318                 pr_err("No memory for uncompressed data; skipping compression\n");
 319                 workspace = NULL;
 320         }
 321 }
 322
 323 static void free_lzo(void)
 324 {
 325         kfree(workspace);
 326         kfree(big_oops_buf);
 327         big_oops_buf = NULL;
 328         big_oops_buf_sz = 0;
 329 }
 330
 331 static const struct pstore_zbackend backend_lzo = {
 332         .compress       = compress_lzo,
 333         .decompress     = decompress_lzo,
 334         .allocate       = allocate_lzo,
 335         .free           = free_lzo,
 336         .name           = "lzo",
 337 };
 338 #endif
 339
 340 #ifdef CONFIG_PSTORE_LZ4_COMPRESS
 341 static int compress_lz4(const void *in, void *out, size_t inlen, size_t outlen)
 342 {
 343         int ret;
 344
 345         ret = LZ4_compress_default(in, out, inlen, outlen, workspace);
 346         if (!ret) {
 347                 pr_err("LZ4_compress_default error; compression failed!\n");
 348                 return -EIO;
 349         }
 350
 351         return ret;
 352 }
 353
 354 static int decompress_lz4(void *in, void *out, size_t inlen, size_t outlen)
 355 {
 356         int ret;
 357
 358         ret = LZ4_decompress_safe(in, out, inlen, outlen);
 359         if (ret < 0) {
 360                 /*
 361                  * LZ4_decompress_safe will return an error code
 362                  * (< 0) if decompression failed
 363                  */
 364                 pr_err("LZ4_decompress_safe error, ret = %d!\n", ret);
 365                 return -EIO;
 366         }
 367
 368         return ret;
 369 }
 370
 371 static void allocate_lz4(void)
 372 {
 373         big_oops_buf_sz = LZ4_compressBound(psinfo->bufsize);
 374         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 375         if (big_oops_buf) {
 376                 workspace = kmalloc(LZ4_MEM_COMPRESS, GFP_KERNEL);
 377                 if (!workspace) {
 378                         pr_err("No memory for compression workspace; skipping compression\n");
 379                         kfree(big_oops_buf);
 380                         big_oops_buf = NULL;
 381                 }
 382         } else {
 383                 pr_err("No memory for uncompressed data; skipping compression\n");
 384                 workspace = NULL;
 385         }
 386 }
 387
 388 static void free_lz4(void)
 389 {
 390         kfree(workspace);
 391         kfree(big_oops_buf);
 392         big_oops_buf = NULL;
 393         big_oops_buf_sz = 0;
 394 }
 395
 396 static const struct pstore_zbackend backend_lz4 = {
 397         .compress       = compress_lz4,
 398         .decompress     = decompress_lz4,
 399         .allocate       = allocate_lz4,
 400         .free           = free_lz4,
 401         .name           = "lz4",
 402 };
 403 #endif
 404
 405 static const struct pstore_zbackend *zbackend =
 406 #if defined(CONFIG_PSTORE_ZLIB_COMPRESS)
 407         &backend_zlib;
 408 #elif defined(CONFIG_PSTORE_LZO_COMPRESS)
 409         &backend_lzo;
 410 #elif defined(CONFIG_PSTORE_LZ4_COMPRESS)
 411         &backend_lz4;
 412 #else
 413         NULL;
 414 #endif
 415
 416 static int pstore_compress(const void *in, void *out,
 417                            size_t inlen, size_t outlen)
 418 {
 419         if (zbackend)
 420                 return zbackend->compress(in, out, inlen, outlen);
 421         else
 422                 return -EIO;
 423 }
 424
 425 static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
 426 {
 427         if (zbackend)
 428                 return zbackend->decompress(in, out, inlen, outlen);
 429         else
 430                 return -EIO;
 431 }
 432
 433 static void allocate_buf_for_compression(void)
 434 {
 435         if (zbackend) {
 436                 pr_info("using %s compression\n", zbackend->name);
 437                 zbackend->allocate();
 438         } else {
 439                 pr_err("allocate compression buffer error!\n");
 440         }
 441 }
 442
 443 static void free_buf_for_compression(void)
 444 {
 445         if (zbackend)
 446                 zbackend->free();
 447         else
 448                 pr_err("free compression buffer error!\n");
 449 }
 450
 451 /*
 452  * Called when compression fails, since the printk buffer
 453  * would be fetched for compression calling it again when
 454  * compression fails would have moved the iterator of
 455  * printk buffer which results in fetching old contents.
 456  * Copy the recent messages from big_oops_buf to psinfo->buf
 457  */
 458 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 459 {
 460         size_t total_len;
 461         size_t diff;
 462
 463         total_len = hsize + len;
 464
 465         if (total_len > psinfo->bufsize) {
 466                 diff = total_len - psinfo->bufsize + hsize;
 467                 memcpy(psinfo->buf, big_oops_buf, hsize);
 468                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 469                                         psinfo->bufsize - hsize);
 470                 total_len = psinfo->bufsize;
 471         } else
 472                 memcpy(psinfo->buf, big_oops_buf, total_len);
 473
 474         return total_len;
 475 }
 476
 477 void pstore_record_init(struct pstore_record *record,
 478                         struct pstore_info *psinfo)
 479 {
 480         memset(record, 0, sizeof(*record));
 481
 482         record->psi = psinfo;
 483
 484         /* Report zeroed timestamp if called before timekeeping has resumed. */
 485         record->time = ns_to_timespec(ktime_get_real_fast_ns());
 486 }
 487
 488 /*
 489  * callback from kmsg_dump. (s2,l2) has the most recently
 490  * written bytes, older bytes are in (s1,l1). Save as much
 491  * as we can from the end of the buffer.
 492  */
 493 static void pstore_dump(struct kmsg_dumper *dumper,
 494                         enum kmsg_dump_reason reason)
 495 {
 496         unsigned long   total = 0;
 497         const char      *why;
 498         unsigned int    part = 1;
 499         unsigned long   flags = 0;
 500         int             is_locked;
 501         int             ret;
 502
 503         why = get_reason_str(reason);
 504
 505         if (pstore_cannot_block_path(reason)) {
 506                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 507                 if (!is_locked) {
 508                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 509                                        , in_nmi() ? "NMI" : why);
 510                         return;
 511                 }
 512         } else {
 513                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 514                 is_locked = 1;
 515         }
 516         oopscount++;
 517         while (total < kmsg_bytes) {
 518                 char *dst;
 519                 size_t dst_size;
 520                 int header_size;
 521                 int zipped_len = -1;
 522                 size_t dump_size;
 523                 struct pstore_record record;
 524
 525                 pstore_record_init(&record, psinfo);
 526                 record.type = PSTORE_TYPE_DMESG;
 527                 record.count = oopscount;
 528                 record.reason = reason;
 529                 record.part = part;
 530                 record.buf = psinfo->buf;
 531
 532                 if (big_oops_buf && is_locked) {
 533                         dst = big_oops_buf;
 534                         dst_size = big_oops_buf_sz;
 535                 } else {
 536                         dst = psinfo->buf;
 537                         dst_size = psinfo->bufsize;
 538                 }
 539
 540                 /* Write dump header. */
 541                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 542                                  oopscount, part);
 543                 dst_size -= header_size;
 544
 545                 /* Write dump contents. */
 546                 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
 547                                           dst_size, &dump_size))
 548                         break;
 549
 550                 if (big_oops_buf && is_locked) {
 551                         zipped_len = pstore_compress(dst, psinfo->buf,
 552                                                 header_size + dump_size,
 553                                                 psinfo->bufsize);
 554
 555                         if (zipped_len > 0) {
 556                                 record.compressed = true;
 557                                 record.size = zipped_len;
 558                         } else {
 559                                 record.size = copy_kmsg_to_buffer(header_size,
 560                                                                   dump_size);
 561                         }
 562                 } else {
 563                         record.size = header_size + dump_size;
 564                 }
 565
 566                 ret = psinfo->write(&record);
 567                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 568                         pstore_new_entry = 1;
 569
 570                 total += record.size;
 571                 part++;
 572         }
 573         if (is_locked)
 574                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 575 }
 576
 577 static struct kmsg_dumper pstore_dumper = {
 578         .dump = pstore_dump,
 579 };
 580
 581 /*
 582  * Register with kmsg_dump to save last part of console log on panic.
 583  */
 584 static void pstore_register_kmsg(void)
 585 {
 586         kmsg_dump_register(&pstore_dumper);
 587 }
 588
 589 static void pstore_unregister_kmsg(void)
 590 {
 591         kmsg_dump_unregister(&pstore_dumper);
 592 }
 593
 594 #ifdef CONFIG_PSTORE_CONSOLE
 595 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 596 {
 597         const char *e = s + c;
 598
 599         while (s < e) {
 600                 struct pstore_record record;
 601                 unsigned long flags;
 602
 603                 pstore_record_init(&record, psinfo);
 604                 record.type = PSTORE_TYPE_CONSOLE;
 605
 606                 if (c > psinfo->bufsize)
 607                         c = psinfo->bufsize;
 608
 609                 if (oops_in_progress) {
 610                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 611                                 break;
 612                 } else {
 613                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 614                 }
 615                 record.buf = (char *)s;
 616                 record.size = c;
 617                 psinfo->write(&record);
 618                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 619                 s += c;
 620                 c = e - s;
 621         }
 622 }
 623
 624 static struct console pstore_console = {
 625         .name   = "pstore",
 626         .write  = pstore_console_write,
 627         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 628         .index  = -1,
 629 };
 630
 631 static void pstore_register_console(void)
 632 {
 633         register_console(&pstore_console);
 634 }
 635
 636 static void pstore_unregister_console(void)
 637 {
 638         unregister_console(&pstore_console);
 639 }
 640 #else
 641 static void pstore_register_console(void) {}
 642 static void pstore_unregister_console(void) {}
 643 #endif
 644
 645 static int pstore_write_user_compat(struct pstore_record *record,
 646                                     const char __user *buf)
 647 {
 648         int ret = 0;
 649
 650         if (record->buf)
 651                 return -EINVAL;
 652
 653         record->buf = memdup_user(buf, record->size);
 654         if (IS_ERR(record->buf)) {
 655                 ret = PTR_ERR(record->buf);
 656                 goto out;
 657         }
 658
 659         ret = record->psi->write(record);
 660
 661         kfree(record->buf);
 662 out:
 663         record->buf = NULL;
 664
 665         return unlikely(ret < 0) ? ret : record->size;
 666 }
 667
 668 /*
 669  * platform specific persistent storage driver registers with
 670  * us here. If pstore is already mounted, call the platform
 671  * read function right away to populate the file system. If not
 672  * then the pstore mount code will call us later to fill out
 673  * the file system.
 674  */
 675 int pstore_register(struct pstore_info *psi)
 676 {
 677         struct module *owner = psi->owner;
 678
 679         if (backend && strcmp(backend, psi->name)) {
 680                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 681                 return -EPERM;
 682         }
 683
 684         /* Sanity check flags. */
 685         if (!psi->flags) {
 686                 pr_warn("backend '%s' must support at least one frontend\n",
 687                         psi->name);
 688                 return -EINVAL;
 689         }
 690
 691         /* Check for required functions. */
 692         if (!psi->read || !psi->write) {
 693                 pr_warn("backend '%s' must implement read() and write()\n",
 694                         psi->name);
 695                 return -EINVAL;
 696         }
 697
 698         spin_lock(&pstore_lock);
 699         if (psinfo) {
 700                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 701                         psinfo->name, psi->name);
 702                 spin_unlock(&pstore_lock);
 703                 return -EBUSY;
 704         }
 705
 706         if (!psi->write_user)
 707                 psi->write_user = pstore_write_user_compat;
 708         psinfo = psi;
 709         mutex_init(&psinfo->read_mutex);
 710         spin_unlock(&pstore_lock);
 711
 712         if (owner && !try_module_get(owner)) {
 713                 psinfo = NULL;
 714                 return -EINVAL;
 715         }
 716
 717         allocate_buf_for_compression();
 718
 719         if (pstore_is_mounted())
 720                 pstore_get_records(0);
 721
 722         if (psi->flags & PSTORE_FLAGS_DMESG)
 723                 pstore_register_kmsg();
 724         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 725                 pstore_register_console();
 726         if (psi->flags & PSTORE_FLAGS_FTRACE)
 727                 pstore_register_ftrace();
 728         if (psi->flags & PSTORE_FLAGS_PMSG)
 729                 pstore_register_pmsg();
 730
 731         /* Start watching for new records, if desired. */
 732         if (pstore_update_ms >= 0) {
 733                 pstore_timer.expires = jiffies +
 734                         msecs_to_jiffies(pstore_update_ms);
 735                 add_timer(&pstore_timer);
 736         }
 737
 738         /*
 739          * Update the module parameter backend, so it is visible
 740          * through /sys/module/pstore/parameters/backend
 741          */
 742         backend = psi->name;
 743
 744         pr_info("Registered %s as persistent store backend\n", psi->name);
 745
 746         module_put(owner);
 747
 748         return 0;
 749 }
 750 EXPORT_SYMBOL_GPL(pstore_register);
 751
 752 void pstore_unregister(struct pstore_info *psi)
 753 {
 754         /* Stop timer and make sure all work has finished. */
 755         pstore_update_ms = -1;
 756         del_timer_sync(&pstore_timer);
 757         flush_work(&pstore_work);
 758
 759         if (psi->flags & PSTORE_FLAGS_PMSG)
 760                 pstore_unregister_pmsg();
 761         if (psi->flags & PSTORE_FLAGS_FTRACE)
 762                 pstore_unregister_ftrace();
 763         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 764                 pstore_unregister_console();
 765         if (psi->flags & PSTORE_FLAGS_DMESG)
 766                 pstore_unregister_kmsg();
 767
 768         free_buf_for_compression();
 769
 770         psinfo = NULL;
 771         backend = NULL;
 772 }
 773 EXPORT_SYMBOL_GPL(pstore_unregister);
 774
 775 static void decompress_record(struct pstore_record *record)
 776 {
 777         int unzipped_len;
 778         char *decompressed;
 779
 780         if (!record->compressed)
 781                 return;
 782
 783         /* Only PSTORE_TYPE_DMESG support compression. */
 784         if (record->type != PSTORE_TYPE_DMESG) {
 785                 pr_warn("ignored compressed record type %d\n", record->type);
 786                 return;
 787         }
 788
 789         /* No compression method has created the common buffer. */
 790         if (!big_oops_buf) {
 791                 pr_warn("no decompression buffer allocated\n");
 792                 return;
 793         }
 794
 795         unzipped_len = pstore_decompress(record->buf, big_oops_buf,
 796                                          record->size, big_oops_buf_sz);
 797         if (unzipped_len <= 0) {
 798                 pr_err("decompression failed: %d\n", unzipped_len);
 799                 return;
 800         }
 801
 802         /* Build new buffer for decompressed contents. */
 803         decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
 804                                GFP_KERNEL);
 805         if (!decompressed) {
 806                 pr_err("decompression ran out of memory\n");
 807                 return;
 808         }
 809         memcpy(decompressed, big_oops_buf, unzipped_len);
 810
 811         /* Append ECC notice to decompressed buffer. */
 812         memcpy(decompressed + unzipped_len, record->buf + record->size,
 813                record->ecc_notice_size);
 814
 815         /* Swap out compresed contents with decompressed contents. */
 816         kfree(record->buf);
 817         record->buf = decompressed;
 818         record->size = unzipped_len;
 819         record->compressed = false;
 820 }
 821
 822 /*
 823  * Read all the records from one persistent store backend. Create
 824  * files in our filesystem.  Don't warn about -EEXIST errors
 825  * when we are re-scanning the backing store looking to add new
 826  * error records.
 827  */
 828 void pstore_get_backend_records(struct pstore_info *psi,
 829                                 struct dentry *root, int quiet)
 830 {
 831         int failed = 0;
 832         unsigned int stop_loop = 65536;
 833
 834         if (!psi || !root)
 835                 return;
 836
 837         mutex_lock(&psi->read_mutex);
 838         if (psi->open && psi->open(psi))
 839                 goto out;
 840
 841         /*
 842          * Backend callback read() allocates record.buf. decompress_record()
 843          * may reallocate record.buf. On success, pstore_mkfile() will keep
 844          * the record.buf, so free it only on failure.
 845          */
 846         for (; stop_loop; stop_loop--) {
 847                 struct pstore_record *record;
 848                 int rc;
 849
 850                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 851                 if (!record) {
 852                         pr_err("out of memory creating record\n");
 853                         break;
 854                 }
 855                 pstore_record_init(record, psi);
 856
 857                 record->size = psi->read(record);
 858
 859                 /* No more records left in backend? */
 860                 if (record->size <= 0) {
 861                         kfree(record);
 862                         break;
 863                 }
 864
 865                 decompress_record(record);
 866                 rc = pstore_mkfile(root, record);
 867                 if (rc) {
 868                         /* pstore_mkfile() did not take record, so free it. */
 869                         kfree(record->buf);
 870                         kfree(record);
 871                         if (rc != -EEXIST || !quiet)
 872                                 failed++;
 873                 }
 874         }
 875         if (psi->close)
 876                 psi->close(psi);
 877 out:
 878         mutex_unlock(&psi->read_mutex);
 879
 880         if (failed)
 881                 pr_warn("failed to create %d record(s) from '%s'\n",
 882                         failed, psi->name);
 883         if (!stop_loop)
 884                 pr_err("looping? Too many records seen from '%s'\n",
 885                         psi->name);
 886 }
 887
 888 static void pstore_dowork(struct work_struct *work)
 889 {
 890         pstore_get_records(1);
 891 }
 892
 893 static void pstore_timefunc(struct timer_list *unused)
 894 {
 895         if (pstore_new_entry) {
 896                 pstore_new_entry = 0;
 897                 schedule_work(&pstore_work);
 898         }
 899
 900         if (pstore_update_ms >= 0)
 901                 mod_timer(&pstore_timer,
 902                           jiffies + msecs_to_jiffies(pstore_update_ms));
 903 }
 904
 905 module_param(backend, charp, 0444);
 906 MODULE_PARM_DESC(backend, "Pstore backend to use");