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(unsigned long);
  65 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
  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         if (__getnstimeofday(&record->time)) {
 486                 record->time.tv_sec = 0;
 487                 record->time.tv_nsec = 0;
 488         }
 489 }
 490
 491 /*
 492  * callback from kmsg_dump. (s2,l2) has the most recently
 493  * written bytes, older bytes are in (s1,l1). Save as much
 494  * as we can from the end of the buffer.
 495  */
 496 static void pstore_dump(struct kmsg_dumper *dumper,
 497                         enum kmsg_dump_reason reason)
 498 {
 499         unsigned long   total = 0;
 500         const char      *why;
 501         unsigned int    part = 1;
 502         unsigned long   flags = 0;
 503         int             is_locked;
 504         int             ret;
 505
 506         why = get_reason_str(reason);
 507
 508         if (pstore_cannot_block_path(reason)) {
 509                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 510                 if (!is_locked) {
 511                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 512                                        , in_nmi() ? "NMI" : why);
 513                         return;
 514                 }
 515         } else {
 516                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 517                 is_locked = 1;
 518         }
 519         oopscount++;
 520         while (total < kmsg_bytes) {
 521                 char *dst;
 522                 size_t dst_size;
 523                 int header_size;
 524                 int zipped_len = -1;
 525                 size_t dump_size;
 526                 struct pstore_record record;
 527
 528                 pstore_record_init(&record, psinfo);
 529                 record.type = PSTORE_TYPE_DMESG;
 530                 record.count = oopscount;
 531                 record.reason = reason;
 532                 record.part = part;
 533                 record.buf = psinfo->buf;
 534
 535                 if (big_oops_buf && is_locked) {
 536                         dst = big_oops_buf;
 537                         dst_size = big_oops_buf_sz;
 538                 } else {
 539                         dst = psinfo->buf;
 540                         dst_size = psinfo->bufsize;
 541                 }
 542
 543                 /* Write dump header. */
 544                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 545                                  oopscount, part);
 546                 dst_size -= header_size;
 547
 548                 /* Write dump contents. */
 549                 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
 550                                           dst_size, &dump_size))
 551                         break;
 552
 553                 if (big_oops_buf && is_locked) {
 554                         zipped_len = pstore_compress(dst, psinfo->buf,
 555                                                 header_size + dump_size,
 556                                                 psinfo->bufsize);
 557
 558                         if (zipped_len > 0) {
 559                                 record.compressed = true;
 560                                 record.size = zipped_len;
 561                         } else {
 562                                 record.size = copy_kmsg_to_buffer(header_size,
 563                                                                   dump_size);
 564                         }
 565                 } else {
 566                         record.size = header_size + dump_size;
 567                 }
 568
 569                 ret = psinfo->write(&record);
 570                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 571                         pstore_new_entry = 1;
 572
 573                 total += record.size;
 574                 part++;
 575         }
 576         if (is_locked)
 577                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 578 }
 579
 580 static struct kmsg_dumper pstore_dumper = {
 581         .dump = pstore_dump,
 582 };
 583
 584 /*
 585  * Register with kmsg_dump to save last part of console log on panic.
 586  */
 587 static void pstore_register_kmsg(void)
 588 {
 589         kmsg_dump_register(&pstore_dumper);
 590 }
 591
 592 static void pstore_unregister_kmsg(void)
 593 {
 594         kmsg_dump_unregister(&pstore_dumper);
 595 }
 596
 597 #ifdef CONFIG_PSTORE_CONSOLE
 598 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 599 {
 600         const char *e = s + c;
 601
 602         while (s < e) {
 603                 struct pstore_record record;
 604                 unsigned long flags;
 605
 606                 pstore_record_init(&record, psinfo);
 607                 record.type = PSTORE_TYPE_CONSOLE;
 608
 609                 if (c > psinfo->bufsize)
 610                         c = psinfo->bufsize;
 611
 612                 if (oops_in_progress) {
 613                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 614                                 break;
 615                 } else {
 616                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 617                 }
 618                 record.buf = (char *)s;
 619                 record.size = c;
 620                 psinfo->write(&record);
 621                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 622                 s += c;
 623                 c = e - s;
 624         }
 625 }
 626
 627 static struct console pstore_console = {
 628         .name   = "pstore",
 629         .write  = pstore_console_write,
 630         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 631         .index  = -1,
 632 };
 633
 634 static void pstore_register_console(void)
 635 {
 636         register_console(&pstore_console);
 637 }
 638
 639 static void pstore_unregister_console(void)
 640 {
 641         unregister_console(&pstore_console);
 642 }
 643 #else
 644 static void pstore_register_console(void) {}
 645 static void pstore_unregister_console(void) {}
 646 #endif
 647
 648 static int pstore_write_user_compat(struct pstore_record *record,
 649                                     const char __user *buf)
 650 {
 651         int ret = 0;
 652
 653         if (record->buf)
 654                 return -EINVAL;
 655
 656         record->buf = memdup_user(buf, record->size);
 657         if (unlikely(IS_ERR(record->buf))) {
 658                 ret = PTR_ERR(record->buf);
 659                 goto out;
 660         }
 661
 662         ret = record->psi->write(record);
 663
 664         kfree(record->buf);
 665 out:
 666         record->buf = NULL;
 667
 668         return unlikely(ret < 0) ? ret : record->size;
 669 }
 670
 671 /*
 672  * platform specific persistent storage driver registers with
 673  * us here. If pstore is already mounted, call the platform
 674  * read function right away to populate the file system. If not
 675  * then the pstore mount code will call us later to fill out
 676  * the file system.
 677  */
 678 int pstore_register(struct pstore_info *psi)
 679 {
 680         struct module *owner = psi->owner;
 681
 682         if (backend && strcmp(backend, psi->name)) {
 683                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 684                 return -EPERM;
 685         }
 686
 687         /* Sanity check flags. */
 688         if (!psi->flags) {
 689                 pr_warn("backend '%s' must support at least one frontend\n",
 690                         psi->name);
 691                 return -EINVAL;
 692         }
 693
 694         /* Check for required functions. */
 695         if (!psi->read || !psi->write) {
 696                 pr_warn("backend '%s' must implement read() and write()\n",
 697                         psi->name);
 698                 return -EINVAL;
 699         }
 700
 701         spin_lock(&pstore_lock);
 702         if (psinfo) {
 703                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 704                         psinfo->name, psi->name);
 705                 spin_unlock(&pstore_lock);
 706                 return -EBUSY;
 707         }
 708
 709         if (!psi->write_user)
 710                 psi->write_user = pstore_write_user_compat;
 711         psinfo = psi;
 712         mutex_init(&psinfo->read_mutex);
 713         spin_unlock(&pstore_lock);
 714
 715         if (owner && !try_module_get(owner)) {
 716                 psinfo = NULL;
 717                 return -EINVAL;
 718         }
 719
 720         allocate_buf_for_compression();
 721
 722         if (pstore_is_mounted())
 723                 pstore_get_records(0);
 724
 725         if (psi->flags & PSTORE_FLAGS_DMESG)
 726                 pstore_register_kmsg();
 727         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 728                 pstore_register_console();
 729         if (psi->flags & PSTORE_FLAGS_FTRACE)
 730                 pstore_register_ftrace();
 731         if (psi->flags & PSTORE_FLAGS_PMSG)
 732                 pstore_register_pmsg();
 733
 734         /* Start watching for new records, if desired. */
 735         if (pstore_update_ms >= 0) {
 736                 pstore_timer.expires = jiffies +
 737                         msecs_to_jiffies(pstore_update_ms);
 738                 add_timer(&pstore_timer);
 739         }
 740
 741         /*
 742          * Update the module parameter backend, so it is visible
 743          * through /sys/module/pstore/parameters/backend
 744          */
 745         backend = psi->name;
 746
 747         pr_info("Registered %s as persistent store backend\n", psi->name);
 748
 749         module_put(owner);
 750
 751         return 0;
 752 }
 753 EXPORT_SYMBOL_GPL(pstore_register);
 754
 755 void pstore_unregister(struct pstore_info *psi)
 756 {
 757         /* Stop timer and make sure all work has finished. */
 758         pstore_update_ms = -1;
 759         del_timer_sync(&pstore_timer);
 760         flush_work(&pstore_work);
 761
 762         if (psi->flags & PSTORE_FLAGS_PMSG)
 763                 pstore_unregister_pmsg();
 764         if (psi->flags & PSTORE_FLAGS_FTRACE)
 765                 pstore_unregister_ftrace();
 766         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 767                 pstore_unregister_console();
 768         if (psi->flags & PSTORE_FLAGS_DMESG)
 769                 pstore_unregister_kmsg();
 770
 771         free_buf_for_compression();
 772
 773         psinfo = NULL;
 774         backend = NULL;
 775 }
 776 EXPORT_SYMBOL_GPL(pstore_unregister);
 777
 778 static void decompress_record(struct pstore_record *record)
 779 {
 780         int unzipped_len;
 781         char *decompressed;
 782
 783         if (!record->compressed)
 784                 return;
 785
 786         /* Only PSTORE_TYPE_DMESG support compression. */
 787         if (record->type != PSTORE_TYPE_DMESG) {
 788                 pr_warn("ignored compressed record type %d\n", record->type);
 789                 return;
 790         }
 791
 792         /* No compression method has created the common buffer. */
 793         if (!big_oops_buf) {
 794                 pr_warn("no decompression buffer allocated\n");
 795                 return;
 796         }
 797
 798         unzipped_len = pstore_decompress(record->buf, big_oops_buf,
 799                                          record->size, big_oops_buf_sz);
 800         if (unzipped_len <= 0) {
 801                 pr_err("decompression failed: %d\n", unzipped_len);
 802                 return;
 803         }
 804
 805         /* Build new buffer for decompressed contents. */
 806         decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
 807                                GFP_KERNEL);
 808         if (!decompressed) {
 809                 pr_err("decompression ran out of memory\n");
 810                 return;
 811         }
 812         memcpy(decompressed, big_oops_buf, unzipped_len);
 813
 814         /* Append ECC notice to decompressed buffer. */
 815         memcpy(decompressed + unzipped_len, record->buf + record->size,
 816                record->ecc_notice_size);
 817
 818         /* Swap out compresed contents with decompressed contents. */
 819         kfree(record->buf);
 820         record->buf = decompressed;
 821         record->size = unzipped_len;
 822         record->compressed = false;
 823 }
 824
 825 /*
 826  * Read all the records from one persistent store backend. Create
 827  * files in our filesystem.  Don't warn about -EEXIST errors
 828  * when we are re-scanning the backing store looking to add new
 829  * error records.
 830  */
 831 void pstore_get_backend_records(struct pstore_info *psi,
 832                                 struct dentry *root, int quiet)
 833 {
 834         int failed = 0;
 835         unsigned int stop_loop = 65536;
 836
 837         if (!psi || !root)
 838                 return;
 839
 840         mutex_lock(&psi->read_mutex);
 841         if (psi->open && psi->open(psi))
 842                 goto out;
 843
 844         /*
 845          * Backend callback read() allocates record.buf. decompress_record()
 846          * may reallocate record.buf. On success, pstore_mkfile() will keep
 847          * the record.buf, so free it only on failure.
 848          */
 849         for (; stop_loop; stop_loop--) {
 850                 struct pstore_record *record;
 851                 int rc;
 852
 853                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 854                 if (!record) {
 855                         pr_err("out of memory creating record\n");
 856                         break;
 857                 }
 858                 pstore_record_init(record, psi);
 859
 860                 record->size = psi->read(record);
 861
 862                 /* No more records left in backend? */
 863                 if (record->size <= 0) {
 864                         kfree(record);
 865                         break;
 866                 }
 867
 868                 decompress_record(record);
 869                 rc = pstore_mkfile(root, record);
 870                 if (rc) {
 871                         /* pstore_mkfile() did not take record, so free it. */
 872                         kfree(record->buf);
 873                         kfree(record);
 874                         if (rc != -EEXIST || !quiet)
 875                                 failed++;
 876                 }
 877         }
 878         if (psi->close)
 879                 psi->close(psi);
 880 out:
 881         mutex_unlock(&psi->read_mutex);
 882
 883         if (failed)
 884                 pr_warn("failed to create %d record(s) from '%s'\n",
 885                         failed, psi->name);
 886         if (!stop_loop)
 887                 pr_err("looping? Too many records seen from '%s'\n",
 888                         psi->name);
 889 }
 890
 891 static void pstore_dowork(struct work_struct *work)
 892 {
 893         pstore_get_records(1);
 894 }
 895
 896 static void pstore_timefunc(unsigned long dummy)
 897 {
 898         if (pstore_new_entry) {
 899                 pstore_new_entry = 0;
 900                 schedule_work(&pstore_work);
 901         }
 902
 903         if (pstore_update_ms >= 0)
 904                 mod_timer(&pstore_timer,
 905                           jiffies + msecs_to_jiffies(pstore_update_ms));
 906 }
 907
 908 module_param(backend, charp, 0444);
 909 MODULE_PARM_DESC(backend, "Pstore backend to use");