fs/pstore/platform.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Persistent Storage - platform driver interface parts.
   4  *
   5  * Copyright (C) 2007-2008 Google, Inc.
   6  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   7  */
   8
   9 #define pr_fmt(fmt) "pstore: " fmt
  10
  11 #include <linux/atomic.h>
  12 #include <linux/types.h>
  13 #include <linux/errno.h>
  14 #include <linux/init.h>
  15 #include <linux/kmsg_dump.h>
  16 #include <linux/console.h>
  17 #include <linux/module.h>
  18 #include <linux/pstore.h>
  19 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
  20 #include <linux/lzo.h>
  21 #endif
  22 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
  23 #include <linux/lz4.h>
  24 #endif
  25 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
  26 #include <linux/zstd.h>
  27 #endif
  28 #include <linux/crypto.h>
  29 #include <linux/string.h>
  30 #include <linux/timer.h>
  31 #include <linux/slab.h>
  32 #include <linux/uaccess.h>
  33 #include <linux/jiffies.h>
  34 #include <linux/workqueue.h>
  35
  36 #include "internal.h"
  37
  38 /*
  39  * We defer making "oops" entries appear in pstore - see
  40  * whether the system is actually still running well enough
  41  * to let someone see the entry
  42  */
  43 static int pstore_update_ms = -1;
  44 module_param_named(update_ms, pstore_update_ms, int, 0600);
  45 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
  46                  "(default is -1, which means runtime updates are disabled; "
  47                  "enabling this option may not be safe; it may lead to further "
  48                  "corruption on Oopses)");
  49
  50 /* Names should be in the same order as the enum pstore_type_id */
  51 static const char * const pstore_type_names[] = {
  52         "dmesg",
  53         "mce",
  54         "console",
  55         "ftrace",
  56         "rtas",
  57         "powerpc-ofw",
  58         "powerpc-common",
  59         "pmsg",
  60         "powerpc-opal",
  61 };
  62
  63 static int pstore_new_entry;
  64
  65 static void pstore_timefunc(struct timer_list *);
  66 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
  67
  68 static void pstore_dowork(struct work_struct *);
  69 static DECLARE_WORK(pstore_work, pstore_dowork);
  70
  71 /*
  72  * psinfo_lock protects "psinfo" during calls to
  73  * pstore_register(), pstore_unregister(), and
  74  * the filesystem mount/unmount routines.
  75  */
  76 static DEFINE_MUTEX(psinfo_lock);
  77 struct pstore_info *psinfo;
  78
  79 static char *backend;
  80 module_param(backend, charp, 0444);
  81 MODULE_PARM_DESC(backend, "specific backend to use");
  82
  83 static char *compress =
  84 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
  85                 CONFIG_PSTORE_COMPRESS_DEFAULT;
  86 #else
  87                 NULL;
  88 #endif
  89 module_param(compress, charp, 0444);
  90 MODULE_PARM_DESC(compress, "compression to use");
  91
  92 /* Compression parameters */
  93 static struct crypto_comp *tfm;
  94
  95 struct pstore_zbackend {
  96         int (*zbufsize)(size_t size);
  97         const char *name;
  98 };
  99
 100 static char *big_oops_buf;
 101 static size_t big_oops_buf_sz;
 102
 103 /* How much of the console log to snapshot */
 104 unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
 105
 106 void pstore_set_kmsg_bytes(int bytes)
 107 {
 108         kmsg_bytes = bytes;
 109 }
 110
 111 /* Tag each group of saved records with a sequence number */
 112 static int      oopscount;
 113
 114 const char *pstore_type_to_name(enum pstore_type_id type)
 115 {
 116         BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
 117
 118         if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
 119                 return "unknown";
 120
 121         return pstore_type_names[type];
 122 }
 123 EXPORT_SYMBOL_GPL(pstore_type_to_name);
 124
 125 enum pstore_type_id pstore_name_to_type(const char *name)
 126 {
 127         int i;
 128
 129         for (i = 0; i < PSTORE_TYPE_MAX; i++) {
 130                 if (!strcmp(pstore_type_names[i], name))
 131                         return i;
 132         }
 133
 134         return PSTORE_TYPE_MAX;
 135 }
 136 EXPORT_SYMBOL_GPL(pstore_name_to_type);
 137
 138 static void pstore_timer_kick(void)
 139 {
 140         if (pstore_update_ms < 0)
 141                 return;
 142
 143         mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 144 }
 145
 146 /*
 147  * Should pstore_dump() wait for a concurrent pstore_dump()? If
 148  * not, the current pstore_dump() will report a failure to dump
 149  * and return.
 150  */
 151 static bool pstore_cannot_wait(enum kmsg_dump_reason reason)
 152 {
 153         /* In NMI path, pstore shouldn't block regardless of reason. */
 154         if (in_nmi())
 155                 return true;
 156
 157         switch (reason) {
 158         /* In panic case, other cpus are stopped by smp_send_stop(). */
 159         case KMSG_DUMP_PANIC:
 160         /* Emergency restart shouldn't be blocked. */
 161         case KMSG_DUMP_EMERG:
 162                 return true;
 163         default:
 164                 return false;
 165         }
 166 }
 167
 168 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 169 static int zbufsize_deflate(size_t size)
 170 {
 171         size_t cmpr;
 172
 173         switch (size) {
 174         /* buffer range for efivars */
 175         case 1000 ... 2000:
 176                 cmpr = 56;
 177                 break;
 178         case 2001 ... 3000:
 179                 cmpr = 54;
 180                 break;
 181         case 3001 ... 3999:
 182                 cmpr = 52;
 183                 break;
 184         /* buffer range for nvram, erst */
 185         case 4000 ... 10000:
 186                 cmpr = 45;
 187                 break;
 188         default:
 189                 cmpr = 60;
 190                 break;
 191         }
 192
 193         return (size * 100) / cmpr;
 194 }
 195 #endif
 196
 197 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 198 static int zbufsize_lzo(size_t size)
 199 {
 200         return lzo1x_worst_compress(size);
 201 }
 202 #endif
 203
 204 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 205 static int zbufsize_lz4(size_t size)
 206 {
 207         return LZ4_compressBound(size);
 208 }
 209 #endif
 210
 211 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 212 static int zbufsize_842(size_t size)
 213 {
 214         return size;
 215 }
 216 #endif
 217
 218 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 219 static int zbufsize_zstd(size_t size)
 220 {
 221         return ZSTD_compressBound(size);
 222 }
 223 #endif
 224
 225 static const struct pstore_zbackend *zbackend __ro_after_init;
 226
 227 static const struct pstore_zbackend zbackends[] = {
 228 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 229         {
 230                 .zbufsize       = zbufsize_deflate,
 231                 .name           = "deflate",
 232         },
 233 #endif
 234 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 235         {
 236                 .zbufsize       = zbufsize_lzo,
 237                 .name           = "lzo",
 238         },
 239 #endif
 240 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
 241         {
 242                 .zbufsize       = zbufsize_lz4,
 243                 .name           = "lz4",
 244         },
 245 #endif
 246 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 247         {
 248                 .zbufsize       = zbufsize_lz4,
 249                 .name           = "lz4hc",
 250         },
 251 #endif
 252 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 253         {
 254                 .zbufsize       = zbufsize_842,
 255                 .name           = "842",
 256         },
 257 #endif
 258 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 259         {
 260                 .zbufsize       = zbufsize_zstd,
 261                 .name           = "zstd",
 262         },
 263 #endif
 264         { }
 265 };
 266
 267 static int pstore_compress(const void *in, void *out,
 268                            unsigned int inlen, unsigned int outlen)
 269 {
 270         int ret;
 271
 272         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESSION))
 273                 return -EINVAL;
 274
 275         ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
 276         if (ret) {
 277                 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
 278                 return ret;
 279         }
 280
 281         return outlen;
 282 }
 283
 284 static void allocate_buf_for_compression(void)
 285 {
 286         struct crypto_comp *ctx;
 287         int size;
 288         char *buf;
 289
 290         /* Skip if not built-in or compression backend not selected yet. */
 291         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
 292                 return;
 293
 294         /* Skip if no pstore backend yet or compression init already done. */
 295         if (!psinfo || tfm)
 296                 return;
 297
 298         if (!crypto_has_comp(zbackend->name, 0, 0)) {
 299                 pr_err("Unknown compression: %s\n", zbackend->name);
 300                 return;
 301         }
 302
 303         size = zbackend->zbufsize(psinfo->bufsize);
 304         if (size <= 0) {
 305                 pr_err("Invalid compression size for %s: %d\n",
 306                        zbackend->name, size);
 307                 return;
 308         }
 309
 310         buf = kmalloc(size, GFP_KERNEL);
 311         if (!buf) {
 312                 pr_err("Failed %d byte compression buffer allocation for: %s\n",
 313                        size, zbackend->name);
 314                 return;
 315         }
 316
 317         ctx = crypto_alloc_comp(zbackend->name, 0, 0);
 318         if (IS_ERR_OR_NULL(ctx)) {
 319                 kfree(buf);
 320                 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
 321                        PTR_ERR(ctx));
 322                 return;
 323         }
 324
 325         /* A non-NULL big_oops_buf indicates compression is available. */
 326         tfm = ctx;
 327         big_oops_buf_sz = size;
 328         big_oops_buf = buf;
 329
 330         pr_info("Using crash dump compression: %s\n", zbackend->name);
 331 }
 332
 333 static void free_buf_for_compression(void)
 334 {
 335         if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
 336                 crypto_free_comp(tfm);
 337                 tfm = NULL;
 338         }
 339         kfree(big_oops_buf);
 340         big_oops_buf = NULL;
 341         big_oops_buf_sz = 0;
 342 }
 343
 344 /*
 345  * Called when compression fails, since the printk buffer
 346  * would be fetched for compression calling it again when
 347  * compression fails would have moved the iterator of
 348  * printk buffer which results in fetching old contents.
 349  * Copy the recent messages from big_oops_buf to psinfo->buf
 350  */
 351 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 352 {
 353         size_t total_len;
 354         size_t diff;
 355
 356         total_len = hsize + len;
 357
 358         if (total_len > psinfo->bufsize) {
 359                 diff = total_len - psinfo->bufsize + hsize;
 360                 memcpy(psinfo->buf, big_oops_buf, hsize);
 361                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 362                                         psinfo->bufsize - hsize);
 363                 total_len = psinfo->bufsize;
 364         } else
 365                 memcpy(psinfo->buf, big_oops_buf, total_len);
 366
 367         return total_len;
 368 }
 369
 370 void pstore_record_init(struct pstore_record *record,
 371                         struct pstore_info *psinfo)
 372 {
 373         memset(record, 0, sizeof(*record));
 374
 375         record->psi = psinfo;
 376
 377         /* Report zeroed timestamp if called before timekeeping has resumed. */
 378         record->time = ns_to_timespec64(ktime_get_real_fast_ns());
 379 }
 380
 381 /*
 382  * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
 383  * end of the buffer.
 384  */
 385 static void pstore_dump(struct kmsg_dumper *dumper,
 386                         enum kmsg_dump_reason reason)
 387 {
 388         unsigned long   total = 0;
 389         const char      *why;
 390         unsigned int    part = 1;
 391         int             ret;
 392
 393         why = kmsg_dump_reason_str(reason);
 394
 395         if (down_trylock(&psinfo->buf_lock)) {
 396                 /* Failed to acquire lock: give up if we cannot wait. */
 397                 if (pstore_cannot_wait(reason)) {
 398                         pr_err("dump skipped in %s path: may corrupt error record\n",
 399                                 in_nmi() ? "NMI" : why);
 400                         return;
 401                 }
 402                 if (down_interruptible(&psinfo->buf_lock)) {
 403                         pr_err("could not grab semaphore?!\n");
 404                         return;
 405                 }
 406         }
 407
 408         oopscount++;
 409         while (total < kmsg_bytes) {
 410                 char *dst;
 411                 size_t dst_size;
 412                 int header_size;
 413                 int zipped_len = -1;
 414                 size_t dump_size;
 415                 struct pstore_record record;
 416
 417                 pstore_record_init(&record, psinfo);
 418                 record.type = PSTORE_TYPE_DMESG;
 419                 record.count = oopscount;
 420                 record.reason = reason;
 421                 record.part = part;
 422                 record.buf = psinfo->buf;
 423
 424                 if (big_oops_buf) {
 425                         dst = big_oops_buf;
 426                         dst_size = big_oops_buf_sz;
 427                 } else {
 428                         dst = psinfo->buf;
 429                         dst_size = psinfo->bufsize;
 430                 }
 431
 432                 /* Write dump header. */
 433                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 434                                  oopscount, part);
 435                 dst_size -= header_size;
 436
 437                 /* Write dump contents. */
 438                 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
 439                                           dst_size, &dump_size))
 440                         break;
 441
 442                 if (big_oops_buf) {
 443                         zipped_len = pstore_compress(dst, psinfo->buf,
 444                                                 header_size + dump_size,
 445                                                 psinfo->bufsize);
 446
 447                         if (zipped_len > 0) {
 448                                 record.compressed = true;
 449                                 record.size = zipped_len;
 450                         } else {
 451                                 record.size = copy_kmsg_to_buffer(header_size,
 452                                                                   dump_size);
 453                         }
 454                 } else {
 455                         record.size = header_size + dump_size;
 456                 }
 457
 458                 ret = psinfo->write(&record);
 459                 if (ret == 0 && reason == KMSG_DUMP_OOPS) {
 460                         pstore_new_entry = 1;
 461                         pstore_timer_kick();
 462                 }
 463
 464                 total += record.size;
 465                 part++;
 466         }
 467
 468         up(&psinfo->buf_lock);
 469 }
 470
 471 static struct kmsg_dumper pstore_dumper = {
 472         .dump = pstore_dump,
 473 };
 474
 475 /*
 476  * Register with kmsg_dump to save last part of console log on panic.
 477  */
 478 static void pstore_register_kmsg(void)
 479 {
 480         kmsg_dump_register(&pstore_dumper);
 481 }
 482
 483 static void pstore_unregister_kmsg(void)
 484 {
 485         kmsg_dump_unregister(&pstore_dumper);
 486 }
 487
 488 #ifdef CONFIG_PSTORE_CONSOLE
 489 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 490 {
 491         struct pstore_record record;
 492
 493         if (!c)
 494                 return;
 495
 496         pstore_record_init(&record, psinfo);
 497         record.type = PSTORE_TYPE_CONSOLE;
 498
 499         record.buf = (char *)s;
 500         record.size = c;
 501         psinfo->write(&record);
 502 }
 503
 504 static struct console pstore_console = {
 505         .write  = pstore_console_write,
 506         .index  = -1,
 507 };
 508
 509 static void pstore_register_console(void)
 510 {
 511         /* Show which backend is going to get console writes. */
 512         strscpy(pstore_console.name, psinfo->name,
 513                 sizeof(pstore_console.name));
 514         /*
 515          * Always initialize flags here since prior unregister_console()
 516          * calls may have changed settings (specifically CON_ENABLED).
 517          */
 518         pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
 519         register_console(&pstore_console);
 520 }
 521
 522 static void pstore_unregister_console(void)
 523 {
 524         unregister_console(&pstore_console);
 525 }
 526 #else
 527 static void pstore_register_console(void) {}
 528 static void pstore_unregister_console(void) {}
 529 #endif
 530
 531 static int pstore_write_user_compat(struct pstore_record *record,
 532                                     const char __user *buf)
 533 {
 534         int ret = 0;
 535
 536         if (record->buf)
 537                 return -EINVAL;
 538
 539         record->buf = memdup_user(buf, record->size);
 540         if (IS_ERR(record->buf)) {
 541                 ret = PTR_ERR(record->buf);
 542                 goto out;
 543         }
 544
 545         ret = record->psi->write(record);
 546
 547         kfree(record->buf);
 548 out:
 549         record->buf = NULL;
 550
 551         return unlikely(ret < 0) ? ret : record->size;
 552 }
 553
 554 /*
 555  * platform specific persistent storage driver registers with
 556  * us here. If pstore is already mounted, call the platform
 557  * read function right away to populate the file system. If not
 558  * then the pstore mount code will call us later to fill out
 559  * the file system.
 560  */
 561 int pstore_register(struct pstore_info *psi)
 562 {
 563         if (backend && strcmp(backend, psi->name)) {
 564                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 565                 return -EPERM;
 566         }
 567
 568         /* Sanity check flags. */
 569         if (!psi->flags) {
 570                 pr_warn("backend '%s' must support at least one frontend\n",
 571                         psi->name);
 572                 return -EINVAL;
 573         }
 574
 575         /* Check for required functions. */
 576         if (!psi->read || !psi->write) {
 577                 pr_warn("backend '%s' must implement read() and write()\n",
 578                         psi->name);
 579                 return -EINVAL;
 580         }
 581
 582         mutex_lock(&psinfo_lock);
 583         if (psinfo) {
 584                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 585                         psinfo->name, psi->name);
 586                 mutex_unlock(&psinfo_lock);
 587                 return -EBUSY;
 588         }
 589
 590         if (!psi->write_user)
 591                 psi->write_user = pstore_write_user_compat;
 592         psinfo = psi;
 593         mutex_init(&psinfo->read_mutex);
 594         sema_init(&psinfo->buf_lock, 1);
 595
 596         if (psi->flags & PSTORE_FLAGS_DMESG)
 597                 allocate_buf_for_compression();
 598
 599         pstore_get_records(0);
 600
 601         if (psi->flags & PSTORE_FLAGS_DMESG) {
 602                 pstore_dumper.max_reason = psinfo->max_reason;
 603                 pstore_register_kmsg();
 604         }
 605         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 606                 pstore_register_console();
 607         if (psi->flags & PSTORE_FLAGS_FTRACE)
 608                 pstore_register_ftrace();
 609         if (psi->flags & PSTORE_FLAGS_PMSG)
 610                 pstore_register_pmsg();
 611
 612         /* Start watching for new records, if desired. */
 613         pstore_timer_kick();
 614
 615         /*
 616          * Update the module parameter backend, so it is visible
 617          * through /sys/module/pstore/parameters/backend
 618          */
 619         backend = kstrdup(psi->name, GFP_KERNEL);
 620
 621         pr_info("Registered %s as persistent store backend\n", psi->name);
 622
 623         mutex_unlock(&psinfo_lock);
 624         return 0;
 625 }
 626 EXPORT_SYMBOL_GPL(pstore_register);
 627
 628 void pstore_unregister(struct pstore_info *psi)
 629 {
 630         /* It's okay to unregister nothing. */
 631         if (!psi)
 632                 return;
 633
 634         mutex_lock(&psinfo_lock);
 635
 636         /* Only one backend can be registered at a time. */
 637         if (WARN_ON(psi != psinfo)) {
 638                 mutex_unlock(&psinfo_lock);
 639                 return;
 640         }
 641
 642         /* Unregister all callbacks. */
 643         if (psi->flags & PSTORE_FLAGS_PMSG)
 644                 pstore_unregister_pmsg();
 645         if (psi->flags & PSTORE_FLAGS_FTRACE)
 646                 pstore_unregister_ftrace();
 647         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 648                 pstore_unregister_console();
 649         if (psi->flags & PSTORE_FLAGS_DMESG)
 650                 pstore_unregister_kmsg();
 651
 652         /* Stop timer and make sure all work has finished. */
 653         del_timer_sync(&pstore_timer);
 654         flush_work(&pstore_work);
 655
 656         /* Remove all backend records from filesystem tree. */
 657         pstore_put_backend_records(psi);
 658
 659         free_buf_for_compression();
 660
 661         psinfo = NULL;
 662         kfree(backend);
 663         backend = NULL;
 664         mutex_unlock(&psinfo_lock);
 665 }
 666 EXPORT_SYMBOL_GPL(pstore_unregister);
 667
 668 static void decompress_record(struct pstore_record *record)
 669 {
 670         int ret;
 671         int unzipped_len;
 672         char *unzipped, *workspace;
 673
 674         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESSION) || !record->compressed)
 675                 return;
 676
 677         /* Only PSTORE_TYPE_DMESG support compression. */
 678         if (record->type != PSTORE_TYPE_DMESG) {
 679                 pr_warn("ignored compressed record type %d\n", record->type);
 680                 return;
 681         }
 682
 683         /* Missing compression buffer means compression was not initialized. */
 684         if (!big_oops_buf) {
 685                 pr_warn("no decompression method initialized!\n");
 686                 return;
 687         }
 688
 689         /* Allocate enough space to hold max decompression and ECC. */
 690         unzipped_len = big_oops_buf_sz;
 691         workspace = kmalloc(unzipped_len + record->ecc_notice_size,
 692                             GFP_KERNEL);
 693         if (!workspace)
 694                 return;
 695
 696         /* After decompression "unzipped_len" is almost certainly smaller. */
 697         ret = crypto_comp_decompress(tfm, record->buf, record->size,
 698                                           workspace, &unzipped_len);
 699         if (ret) {
 700                 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
 701                 kfree(workspace);
 702                 return;
 703         }
 704
 705         /* Append ECC notice to decompressed buffer. */
 706         memcpy(workspace + unzipped_len, record->buf + record->size,
 707                record->ecc_notice_size);
 708
 709         /* Copy decompressed contents into an minimum-sized allocation. */
 710         unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
 711                            GFP_KERNEL);
 712         kfree(workspace);
 713         if (!unzipped)
 714                 return;
 715
 716         /* Swap out compressed contents with decompressed contents. */
 717         kfree(record->buf);
 718         record->buf = unzipped;
 719         record->size = unzipped_len;
 720         record->compressed = false;
 721 }
 722
 723 /*
 724  * Read all the records from one persistent store backend. Create
 725  * files in our filesystem.  Don't warn about -EEXIST errors
 726  * when we are re-scanning the backing store looking to add new
 727  * error records.
 728  */
 729 void pstore_get_backend_records(struct pstore_info *psi,
 730                                 struct dentry *root, int quiet)
 731 {
 732         int failed = 0;
 733         unsigned int stop_loop = 65536;
 734
 735         if (!psi || !root)
 736                 return;
 737
 738         mutex_lock(&psi->read_mutex);
 739         if (psi->open && psi->open(psi))
 740                 goto out;
 741
 742         /*
 743          * Backend callback read() allocates record.buf. decompress_record()
 744          * may reallocate record.buf. On success, pstore_mkfile() will keep
 745          * the record.buf, so free it only on failure.
 746          */
 747         for (; stop_loop; stop_loop--) {
 748                 struct pstore_record *record;
 749                 int rc;
 750
 751                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 752                 if (!record) {
 753                         pr_err("out of memory creating record\n");
 754                         break;
 755                 }
 756                 pstore_record_init(record, psi);
 757
 758                 record->size = psi->read(record);
 759
 760                 /* No more records left in backend? */
 761                 if (record->size <= 0) {
 762                         kfree(record);
 763                         break;
 764                 }
 765
 766                 decompress_record(record);
 767                 rc = pstore_mkfile(root, record);
 768                 if (rc) {
 769                         /* pstore_mkfile() did not take record, so free it. */
 770                         kfree(record->buf);
 771                         kfree(record);
 772                         if (rc != -EEXIST || !quiet)
 773                                 failed++;
 774                 }
 775         }
 776         if (psi->close)
 777                 psi->close(psi);
 778 out:
 779         mutex_unlock(&psi->read_mutex);
 780
 781         if (failed)
 782                 pr_warn("failed to create %d record(s) from '%s'\n",
 783                         failed, psi->name);
 784         if (!stop_loop)
 785                 pr_err("looping? Too many records seen from '%s'\n",
 786                         psi->name);
 787 }
 788
 789 static void pstore_dowork(struct work_struct *work)
 790 {
 791         pstore_get_records(1);
 792 }
 793
 794 static void pstore_timefunc(struct timer_list *unused)
 795 {
 796         if (pstore_new_entry) {
 797                 pstore_new_entry = 0;
 798                 schedule_work(&pstore_work);
 799         }
 800
 801         pstore_timer_kick();
 802 }
 803
 804 static void __init pstore_choose_compression(void)
 805 {
 806         const struct pstore_zbackend *step;
 807
 808         if (!compress)
 809                 return;
 810
 811         for (step = zbackends; step->name; step++) {
 812                 if (!strcmp(compress, step->name)) {
 813                         zbackend = step;
 814                         return;
 815                 }
 816         }
 817 }
 818
 819 static int __init pstore_init(void)
 820 {
 821         int ret;
 822
 823         pstore_choose_compression();
 824
 825         /*
 826          * Check if any pstore backends registered earlier but did not
 827          * initialize compression because crypto was not ready. If so,
 828          * initialize compression now.
 829          */
 830         allocate_buf_for_compression();
 831
 832         ret = pstore_init_fs();
 833         if (ret)
 834                 free_buf_for_compression();
 835
 836         return ret;
 837 }
 838 late_initcall(pstore_init);
 839
 840 static void __exit pstore_exit(void)
 841 {
 842         pstore_exit_fs();
 843 }
 844 module_exit(pstore_exit)
 845
 846 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 847 MODULE_LICENSE("GPL");