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