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 static unsigned long kmsg_bytes = 10240;
 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 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 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(in, inlen, out, &outlen, workspace);
 346         if (ret) {
 347                 pr_err("lz4_compress error, ret = %d!\n", ret);
 348                 return -EIO;
 349         }
 350
 351         return outlen;
 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_unknownoutputsize(in, inlen, out, &outlen);
 359         if (ret) {
 360                 pr_err("lz4_decompress error, ret = %d!\n", ret);
 361                 return -EIO;
 362         }
 363
 364         return outlen;
 365 }
 366
 367 static void allocate_lz4(void)
 368 {
 369         big_oops_buf_sz = lz4_compressbound(psinfo->bufsize);
 370         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 371         if (big_oops_buf) {
 372                 workspace = kmalloc(LZ4_MEM_COMPRESS, GFP_KERNEL);
 373                 if (!workspace) {
 374                         pr_err("No memory for compression workspace; skipping compression\n");
 375                         kfree(big_oops_buf);
 376                         big_oops_buf = NULL;
 377                 }
 378         } else {
 379                 pr_err("No memory for uncompressed data; skipping compression\n");
 380                 workspace = NULL;
 381         }
 382 }
 383
 384 static void free_lz4(void)
 385 {
 386         kfree(workspace);
 387         kfree(big_oops_buf);
 388         big_oops_buf = NULL;
 389         big_oops_buf_sz = 0;
 390 }
 391
 392 static struct pstore_zbackend backend_lz4 = {
 393         .compress       = compress_lz4,
 394         .decompress     = decompress_lz4,
 395         .allocate       = allocate_lz4,
 396         .free           = free_lz4,
 397         .name           = "lz4",
 398 };
 399 #endif
 400
 401 static struct pstore_zbackend *zbackend =
 402 #if defined(CONFIG_PSTORE_ZLIB_COMPRESS)
 403         &backend_zlib;
 404 #elif defined(CONFIG_PSTORE_LZO_COMPRESS)
 405         &backend_lzo;
 406 #elif defined(CONFIG_PSTORE_LZ4_COMPRESS)
 407         &backend_lz4;
 408 #else
 409         NULL;
 410 #endif
 411
 412 static int pstore_compress(const void *in, void *out,
 413                            size_t inlen, size_t outlen)
 414 {
 415         if (zbackend)
 416                 return zbackend->compress(in, out, inlen, outlen);
 417         else
 418                 return -EIO;
 419 }
 420
 421 static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
 422 {
 423         if (zbackend)
 424                 return zbackend->decompress(in, out, inlen, outlen);
 425         else
 426                 return -EIO;
 427 }
 428
 429 static void allocate_buf_for_compression(void)
 430 {
 431         if (zbackend) {
 432                 pr_info("using %s compression\n", zbackend->name);
 433                 zbackend->allocate();
 434         } else {
 435                 pr_err("allocate compression buffer error!\n");
 436         }
 437 }
 438
 439 static void free_buf_for_compression(void)
 440 {
 441         if (zbackend)
 442                 zbackend->free();
 443         else
 444                 pr_err("free compression buffer error!\n");
 445 }
 446
 447 /*
 448  * Called when compression fails, since the printk buffer
 449  * would be fetched for compression calling it again when
 450  * compression fails would have moved the iterator of
 451  * printk buffer which results in fetching old contents.
 452  * Copy the recent messages from big_oops_buf to psinfo->buf
 453  */
 454 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 455 {
 456         size_t total_len;
 457         size_t diff;
 458
 459         total_len = hsize + len;
 460
 461         if (total_len > psinfo->bufsize) {
 462                 diff = total_len - psinfo->bufsize + hsize;
 463                 memcpy(psinfo->buf, big_oops_buf, hsize);
 464                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 465                                         psinfo->bufsize - hsize);
 466                 total_len = psinfo->bufsize;
 467         } else
 468                 memcpy(psinfo->buf, big_oops_buf, total_len);
 469
 470         return total_len;
 471 }
 472
 473 /*
 474  * callback from kmsg_dump. (s2,l2) has the most recently
 475  * written bytes, older bytes are in (s1,l1). Save as much
 476  * as we can from the end of the buffer.
 477  */
 478 static void pstore_dump(struct kmsg_dumper *dumper,
 479                         enum kmsg_dump_reason reason)
 480 {
 481         unsigned long   total = 0;
 482         const char      *why;
 483         u64             id;
 484         unsigned int    part = 1;
 485         unsigned long   flags = 0;
 486         int             is_locked;
 487         int             ret;
 488
 489         why = get_reason_str(reason);
 490
 491         if (pstore_cannot_block_path(reason)) {
 492                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 493                 if (!is_locked) {
 494                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 495                                        , in_nmi() ? "NMI" : why);
 496                         return;
 497                 }
 498         } else {
 499                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 500                 is_locked = 1;
 501         }
 502         oopscount++;
 503         while (total < kmsg_bytes) {
 504                 char *dst;
 505                 unsigned long size;
 506                 int hsize;
 507                 int zipped_len = -1;
 508                 size_t len;
 509                 bool compressed = false;
 510                 size_t total_len;
 511
 512                 if (big_oops_buf && is_locked) {
 513                         dst = big_oops_buf;
 514                         size = big_oops_buf_sz;
 515                 } else {
 516                         dst = psinfo->buf;
 517                         size = psinfo->bufsize;
 518                 }
 519
 520                 hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount, part);
 521                 size -= hsize;
 522
 523                 if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
 524                                           size, &len))
 525                         break;
 526
 527                 if (big_oops_buf && is_locked) {
 528                         zipped_len = pstore_compress(dst, psinfo->buf,
 529                                                 hsize + len, psinfo->bufsize);
 530
 531                         if (zipped_len > 0) {
 532                                 compressed = true;
 533                                 total_len = zipped_len;
 534                         } else {
 535                                 total_len = copy_kmsg_to_buffer(hsize, len);
 536                         }
 537                 } else {
 538                         total_len = hsize + len;
 539                 }
 540
 541                 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
 542                                     oopscount, compressed, total_len, psinfo);
 543                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 544                         pstore_new_entry = 1;
 545
 546                 total += total_len;
 547                 part++;
 548         }
 549         if (is_locked)
 550                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 551 }
 552
 553 static struct kmsg_dumper pstore_dumper = {
 554         .dump = pstore_dump,
 555 };
 556
 557 /*
 558  * Register with kmsg_dump to save last part of console log on panic.
 559  */
 560 static void pstore_register_kmsg(void)
 561 {
 562         kmsg_dump_register(&pstore_dumper);
 563 }
 564
 565 static void pstore_unregister_kmsg(void)
 566 {
 567         kmsg_dump_unregister(&pstore_dumper);
 568 }
 569
 570 #ifdef CONFIG_PSTORE_CONSOLE
 571 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 572 {
 573         const char *e = s + c;
 574
 575         while (s < e) {
 576                 unsigned long flags;
 577                 u64 id;
 578
 579                 if (c > psinfo->bufsize)
 580                         c = psinfo->bufsize;
 581
 582                 if (oops_in_progress) {
 583                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 584                                 break;
 585                 } else {
 586                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 587                 }
 588                 psinfo->write_buf(PSTORE_TYPE_CONSOLE, 0, &id, 0,
 589                                   s, 0, c, psinfo);
 590                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 591                 s += c;
 592                 c = e - s;
 593         }
 594 }
 595
 596 static struct console pstore_console = {
 597         .name   = "pstore",
 598         .write  = pstore_console_write,
 599         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 600         .index  = -1,
 601 };
 602
 603 static void pstore_register_console(void)
 604 {
 605         register_console(&pstore_console);
 606 }
 607
 608 static void pstore_unregister_console(void)
 609 {
 610         unregister_console(&pstore_console);
 611 }
 612 #else
 613 static void pstore_register_console(void) {}
 614 static void pstore_unregister_console(void) {}
 615 #endif
 616
 617 static int pstore_write_compat(enum pstore_type_id type,
 618                                enum kmsg_dump_reason reason,
 619                                u64 *id, unsigned int part, int count,
 620                                bool compressed, size_t size,
 621                                struct pstore_info *psi)
 622 {
 623         return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
 624                              size, psi);
 625 }
 626
 627 static int pstore_write_buf_user_compat(enum pstore_type_id type,
 628                                enum kmsg_dump_reason reason,
 629                                u64 *id, unsigned int part,
 630                                const char __user *buf,
 631                                bool compressed, size_t size,
 632                                struct pstore_info *psi)
 633 {
 634         unsigned long flags = 0;
 635         size_t i, bufsize = size;
 636         long ret = 0;
 637
 638         if (unlikely(!access_ok(VERIFY_READ, buf, size)))
 639                 return -EFAULT;
 640         if (bufsize > psinfo->bufsize)
 641                 bufsize = psinfo->bufsize;
 642         spin_lock_irqsave(&psinfo->buf_lock, flags);
 643         for (i = 0; i < size; ) {
 644                 size_t c = min(size - i, bufsize);
 645
 646                 ret = __copy_from_user(psinfo->buf, buf + i, c);
 647                 if (unlikely(ret != 0)) {
 648                         ret = -EFAULT;
 649                         break;
 650                 }
 651                 ret = psi->write_buf(type, reason, id, part, psinfo->buf,
 652                                      compressed, c, psi);
 653                 if (unlikely(ret < 0))
 654                         break;
 655                 i += c;
 656         }
 657         spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 658         return unlikely(ret < 0) ? ret : size;
 659 }
 660
 661 /*
 662  * platform specific persistent storage driver registers with
 663  * us here. If pstore is already mounted, call the platform
 664  * read function right away to populate the file system. If not
 665  * then the pstore mount code will call us later to fill out
 666  * the file system.
 667  */
 668 int pstore_register(struct pstore_info *psi)
 669 {
 670         struct module *owner = psi->owner;
 671
 672         if (backend && strcmp(backend, psi->name))
 673                 return -EPERM;
 674
 675         spin_lock(&pstore_lock);
 676         if (psinfo) {
 677                 spin_unlock(&pstore_lock);
 678                 return -EBUSY;
 679         }
 680
 681         if (!psi->write)
 682                 psi->write = pstore_write_compat;
 683         if (!psi->write_buf_user)
 684                 psi->write_buf_user = pstore_write_buf_user_compat;
 685         psinfo = psi;
 686         mutex_init(&psinfo->read_mutex);
 687         spin_unlock(&pstore_lock);
 688
 689         if (owner && !try_module_get(owner)) {
 690                 psinfo = NULL;
 691                 return -EINVAL;
 692         }
 693
 694         allocate_buf_for_compression();
 695
 696         if (pstore_is_mounted())
 697                 pstore_get_records(0);
 698
 699         if (psi->flags & PSTORE_FLAGS_DMESG)
 700                 pstore_register_kmsg();
 701         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 702                 pstore_register_console();
 703         if (psi->flags & PSTORE_FLAGS_FTRACE)
 704                 pstore_register_ftrace();
 705         if (psi->flags & PSTORE_FLAGS_PMSG)
 706                 pstore_register_pmsg();
 707
 708         if (pstore_update_ms >= 0) {
 709                 pstore_timer.expires = jiffies +
 710                         msecs_to_jiffies(pstore_update_ms);
 711                 add_timer(&pstore_timer);
 712         }
 713
 714         /*
 715          * Update the module parameter backend, so it is visible
 716          * through /sys/module/pstore/parameters/backend
 717          */
 718         backend = psi->name;
 719
 720         module_put(owner);
 721
 722         pr_info("Registered %s as persistent store backend\n", psi->name);
 723
 724         return 0;
 725 }
 726 EXPORT_SYMBOL_GPL(pstore_register);
 727
 728 void pstore_unregister(struct pstore_info *psi)
 729 {
 730         if (psi->flags & PSTORE_FLAGS_PMSG)
 731                 pstore_unregister_pmsg();
 732         if (psi->flags & PSTORE_FLAGS_FTRACE)
 733                 pstore_unregister_ftrace();
 734         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 735                 pstore_unregister_console();
 736         if (psi->flags & PSTORE_FLAGS_DMESG)
 737                 pstore_unregister_kmsg();
 738
 739         free_buf_for_compression();
 740
 741         psinfo = NULL;
 742         backend = NULL;
 743 }
 744 EXPORT_SYMBOL_GPL(pstore_unregister);
 745
 746 /*
 747  * Read all the records from the persistent store. Create
 748  * files in our filesystem.  Don't warn about -EEXIST errors
 749  * when we are re-scanning the backing store looking to add new
 750  * error records.
 751  */
 752 void pstore_get_records(int quiet)
 753 {
 754         struct pstore_info *psi = psinfo;
 755         char                    *buf = NULL;
 756         ssize_t                 size;
 757         u64                     id;
 758         int                     count;
 759         enum pstore_type_id     type;
 760         struct timespec         time;
 761         int                     failed = 0, rc;
 762         bool                    compressed;
 763         int                     unzipped_len = -1;
 764         ssize_t                 ecc_notice_size = 0;
 765
 766         if (!psi)
 767                 return;
 768
 769         mutex_lock(&psi->read_mutex);
 770         if (psi->open && psi->open(psi))
 771                 goto out;
 772
 773         while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
 774                                  &ecc_notice_size, psi)) > 0) {
 775                 if (compressed && (type == PSTORE_TYPE_DMESG)) {
 776                         if (big_oops_buf)
 777                                 unzipped_len = pstore_decompress(buf,
 778                                                         big_oops_buf, size,
 779                                                         big_oops_buf_sz);
 780
 781                         if (unzipped_len > 0) {
 782                                 if (ecc_notice_size)
 783                                         memcpy(big_oops_buf + unzipped_len,
 784                                                buf + size, ecc_notice_size);
 785                                 kfree(buf);
 786                                 buf = big_oops_buf;
 787                                 size = unzipped_len;
 788                                 compressed = false;
 789                         } else {
 790                                 pr_err("decompression failed;returned %d\n",
 791                                        unzipped_len);
 792                                 compressed = true;
 793                         }
 794                 }
 795                 rc = pstore_mkfile(type, psi->name, id, count, buf,
 796                                    compressed, size + ecc_notice_size,
 797                                    time, psi);
 798                 if (unzipped_len < 0) {
 799                         /* Free buffer other than big oops */
 800                         kfree(buf);
 801                         buf = NULL;
 802                 } else
 803                         unzipped_len = -1;
 804                 if (rc && (rc != -EEXIST || !quiet))
 805                         failed++;
 806         }
 807         if (psi->close)
 808                 psi->close(psi);
 809 out:
 810         mutex_unlock(&psi->read_mutex);
 811
 812         if (failed)
 813                 pr_warn("failed to load %d record(s) from '%s'\n",
 814                         failed, psi->name);
 815 }
 816
 817 static void pstore_dowork(struct work_struct *work)
 818 {
 819         pstore_get_records(1);
 820 }
 821
 822 static void pstore_timefunc(unsigned long dummy)
 823 {
 824         if (pstore_new_entry) {
 825                 pstore_new_entry = 0;
 826                 schedule_work(&pstore_work);
 827         }
 828
 829         mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 830 }
 831
 832 module_param(backend, charp, 0444);
 833 MODULE_PARM_DESC(backend, "Pstore backend to use");