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