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_COMPRESS))
 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         struct kmsg_dump_iter iter;
 389         unsigned long   total = 0;
 390         const char      *why;
 391         unsigned int    part = 1;
 392         int             ret;
 393
 394         why = kmsg_dump_reason_str(reason);
 395
 396         if (down_trylock(&psinfo->buf_lock)) {
 397                 /* Failed to acquire lock: give up if we cannot wait. */
 398                 if (pstore_cannot_wait(reason)) {
 399                         pr_err("dump skipped in %s path: may corrupt error record\n",
 400                                 in_nmi() ? "NMI" : why);
 401                         return;
 402                 }
 403                 if (down_interruptible(&psinfo->buf_lock)) {
 404                         pr_err("could not grab semaphore?!\n");
 405                         return;
 406                 }
 407         }
 408
 409         kmsg_dump_rewind(&iter);
 410
 411         oopscount++;
 412         while (total < kmsg_bytes) {
 413                 char *dst;
 414                 size_t dst_size;
 415                 int header_size;
 416                 int zipped_len = -1;
 417                 size_t dump_size;
 418                 struct pstore_record record;
 419
 420                 pstore_record_init(&record, psinfo);
 421                 record.type = PSTORE_TYPE_DMESG;
 422                 record.count = oopscount;
 423                 record.reason = reason;
 424                 record.part = part;
 425                 record.buf = psinfo->buf;
 426
 427                 if (big_oops_buf) {
 428                         dst = big_oops_buf;
 429                         dst_size = big_oops_buf_sz;
 430                 } else {
 431                         dst = psinfo->buf;
 432                         dst_size = psinfo->bufsize;
 433                 }
 434
 435                 /* Write dump header. */
 436                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 437                                  oopscount, part);
 438                 dst_size -= header_size;
 439
 440                 /* Write dump contents. */
 441                 if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
 442                                           dst_size, &dump_size))
 443                         break;
 444
 445                 if (big_oops_buf) {
 446                         zipped_len = pstore_compress(dst, psinfo->buf,
 447                                                 header_size + dump_size,
 448                                                 psinfo->bufsize);
 449
 450                         if (zipped_len > 0) {
 451                                 record.compressed = true;
 452                                 record.size = zipped_len;
 453                         } else {
 454                                 record.size = copy_kmsg_to_buffer(header_size,
 455                                                                   dump_size);
 456                         }
 457                 } else {
 458                         record.size = header_size + dump_size;
 459                 }
 460
 461                 ret = psinfo->write(&record);
 462                 if (ret == 0 && reason == KMSG_DUMP_OOPS) {
 463                         pstore_new_entry = 1;
 464                         pstore_timer_kick();
 465                 }
 466
 467                 total += record.size;
 468                 part++;
 469         }
 470
 471         up(&psinfo->buf_lock);
 472 }
 473
 474 static struct kmsg_dumper pstore_dumper = {
 475         .dump = pstore_dump,
 476 };
 477
 478 /*
 479  * Register with kmsg_dump to save last part of console log on panic.
 480  */
 481 static void pstore_register_kmsg(void)
 482 {
 483         kmsg_dump_register(&pstore_dumper);
 484 }
 485
 486 static void pstore_unregister_kmsg(void)
 487 {
 488         kmsg_dump_unregister(&pstore_dumper);
 489 }
 490
 491 #ifdef CONFIG_PSTORE_CONSOLE
 492 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 493 {
 494         struct pstore_record record;
 495
 496         if (!c)
 497                 return;
 498
 499         pstore_record_init(&record, psinfo);
 500         record.type = PSTORE_TYPE_CONSOLE;
 501
 502         record.buf = (char *)s;
 503         record.size = c;
 504         psinfo->write(&record);
 505 }
 506
 507 static struct console pstore_console = {
 508         .write  = pstore_console_write,
 509         .index  = -1,
 510 };
 511
 512 static void pstore_register_console(void)
 513 {
 514         /* Show which backend is going to get console writes. */
 515         strscpy(pstore_console.name, psinfo->name,
 516                 sizeof(pstore_console.name));
 517         /*
 518          * Always initialize flags here since prior unregister_console()
 519          * calls may have changed settings (specifically CON_ENABLED).
 520          */
 521         pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
 522         register_console(&pstore_console);
 523 }
 524
 525 static void pstore_unregister_console(void)
 526 {
 527         unregister_console(&pstore_console);
 528 }
 529 #else
 530 static void pstore_register_console(void) {}
 531 static void pstore_unregister_console(void) {}
 532 #endif
 533
 534 static int pstore_write_user_compat(struct pstore_record *record,
 535                                     const char __user *buf)
 536 {
 537         int ret = 0;
 538
 539         if (record->buf)
 540                 return -EINVAL;
 541
 542         record->buf = memdup_user(buf, record->size);
 543         if (IS_ERR(record->buf)) {
 544                 ret = PTR_ERR(record->buf);
 545                 goto out;
 546         }
 547
 548         ret = record->psi->write(record);
 549
 550         kfree(record->buf);
 551 out:
 552         record->buf = NULL;
 553
 554         return unlikely(ret < 0) ? ret : record->size;
 555 }
 556
 557 /*
 558  * platform specific persistent storage driver registers with
 559  * us here. If pstore is already mounted, call the platform
 560  * read function right away to populate the file system. If not
 561  * then the pstore mount code will call us later to fill out
 562  * the file system.
 563  */
 564 int pstore_register(struct pstore_info *psi)
 565 {
 566         if (backend && strcmp(backend, psi->name)) {
 567                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 568                 return -EPERM;
 569         }
 570
 571         /* Sanity check flags. */
 572         if (!psi->flags) {
 573                 pr_warn("backend '%s' must support at least one frontend\n",
 574                         psi->name);
 575                 return -EINVAL;
 576         }
 577
 578         /* Check for required functions. */
 579         if (!psi->read || !psi->write) {
 580                 pr_warn("backend '%s' must implement read() and write()\n",
 581                         psi->name);
 582                 return -EINVAL;
 583         }
 584
 585         mutex_lock(&psinfo_lock);
 586         if (psinfo) {
 587                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 588                         psinfo->name, psi->name);
 589                 mutex_unlock(&psinfo_lock);
 590                 return -EBUSY;
 591         }
 592
 593         if (!psi->write_user)
 594                 psi->write_user = pstore_write_user_compat;
 595         psinfo = psi;
 596         mutex_init(&psinfo->read_mutex);
 597         sema_init(&psinfo->buf_lock, 1);
 598
 599         if (psi->flags & PSTORE_FLAGS_DMESG)
 600                 allocate_buf_for_compression();
 601
 602         pstore_get_records(0);
 603
 604         if (psi->flags & PSTORE_FLAGS_DMESG) {
 605                 pstore_dumper.max_reason = psinfo->max_reason;
 606                 pstore_register_kmsg();
 607         }
 608         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 609                 pstore_register_console();
 610         if (psi->flags & PSTORE_FLAGS_FTRACE)
 611                 pstore_register_ftrace();
 612         if (psi->flags & PSTORE_FLAGS_PMSG)
 613                 pstore_register_pmsg();
 614
 615         /* Start watching for new records, if desired. */
 616         pstore_timer_kick();
 617
 618         /*
 619          * Update the module parameter backend, so it is visible
 620          * through /sys/module/pstore/parameters/backend
 621          */
 622         backend = kstrdup(psi->name, GFP_KERNEL);
 623
 624         pr_info("Registered %s as persistent store backend\n", psi->name);
 625
 626         mutex_unlock(&psinfo_lock);
 627         return 0;
 628 }
 629 EXPORT_SYMBOL_GPL(pstore_register);
 630
 631 void pstore_unregister(struct pstore_info *psi)
 632 {
 633         /* It's okay to unregister nothing. */
 634         if (!psi)
 635                 return;
 636
 637         mutex_lock(&psinfo_lock);
 638
 639         /* Only one backend can be registered at a time. */
 640         if (WARN_ON(psi != psinfo)) {
 641                 mutex_unlock(&psinfo_lock);
 642                 return;
 643         }
 644
 645         /* Unregister all callbacks. */
 646         if (psi->flags & PSTORE_FLAGS_PMSG)
 647                 pstore_unregister_pmsg();
 648         if (psi->flags & PSTORE_FLAGS_FTRACE)
 649                 pstore_unregister_ftrace();
 650         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 651                 pstore_unregister_console();
 652         if (psi->flags & PSTORE_FLAGS_DMESG)
 653                 pstore_unregister_kmsg();
 654
 655         /* Stop timer and make sure all work has finished. */
 656         del_timer_sync(&pstore_timer);
 657         flush_work(&pstore_work);
 658
 659         /* Remove all backend records from filesystem tree. */
 660         pstore_put_backend_records(psi);
 661
 662         free_buf_for_compression();
 663
 664         psinfo = NULL;
 665         kfree(backend);
 666         backend = NULL;
 667         mutex_unlock(&psinfo_lock);
 668 }
 669 EXPORT_SYMBOL_GPL(pstore_unregister);
 670
 671 static void decompress_record(struct pstore_record *record)
 672 {
 673         int ret;
 674         int unzipped_len;
 675         char *unzipped, *workspace;
 676
 677         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
 678                 return;
 679
 680         /* Only PSTORE_TYPE_DMESG support compression. */
 681         if (record->type != PSTORE_TYPE_DMESG) {
 682                 pr_warn("ignored compressed record type %d\n", record->type);
 683                 return;
 684         }
 685
 686         /* Missing compression buffer means compression was not initialized. */
 687         if (!big_oops_buf) {
 688                 pr_warn("no decompression method initialized!\n");
 689                 return;
 690         }
 691
 692         /* Allocate enough space to hold max decompression and ECC. */
 693         unzipped_len = big_oops_buf_sz;
 694         workspace = kmalloc(unzipped_len + record->ecc_notice_size,
 695                             GFP_KERNEL);
 696         if (!workspace)
 697                 return;
 698
 699         /* After decompression "unzipped_len" is almost certainly smaller. */
 700         ret = crypto_comp_decompress(tfm, record->buf, record->size,
 701                                           workspace, &unzipped_len);
 702         if (ret) {
 703                 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
 704                 kfree(workspace);
 705                 return;
 706         }
 707
 708         /* Append ECC notice to decompressed buffer. */
 709         memcpy(workspace + unzipped_len, record->buf + record->size,
 710                record->ecc_notice_size);
 711
 712         /* Copy decompressed contents into an minimum-sized allocation. */
 713         unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
 714                            GFP_KERNEL);
 715         kfree(workspace);
 716         if (!unzipped)
 717                 return;
 718
 719         /* Swap out compressed contents with decompressed contents. */
 720         kfree(record->buf);
 721         record->buf = unzipped;
 722         record->size = unzipped_len;
 723         record->compressed = false;
 724 }
 725
 726 /*
 727  * Read all the records from one persistent store backend. Create
 728  * files in our filesystem.  Don't warn about -EEXIST errors
 729  * when we are re-scanning the backing store looking to add new
 730  * error records.
 731  */
 732 void pstore_get_backend_records(struct pstore_info *psi,
 733                                 struct dentry *root, int quiet)
 734 {
 735         int failed = 0;
 736         unsigned int stop_loop = 65536;
 737
 738         if (!psi || !root)
 739                 return;
 740
 741         mutex_lock(&psi->read_mutex);
 742         if (psi->open && psi->open(psi))
 743                 goto out;
 744
 745         /*
 746          * Backend callback read() allocates record.buf. decompress_record()
 747          * may reallocate record.buf. On success, pstore_mkfile() will keep
 748          * the record.buf, so free it only on failure.
 749          */
 750         for (; stop_loop; stop_loop--) {
 751                 struct pstore_record *record;
 752                 int rc;
 753
 754                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 755                 if (!record) {
 756                         pr_err("out of memory creating record\n");
 757                         break;
 758                 }
 759                 pstore_record_init(record, psi);
 760
 761                 record->size = psi->read(record);
 762
 763                 /* No more records left in backend? */
 764                 if (record->size <= 0) {
 765                         kfree(record);
 766                         break;
 767                 }
 768
 769                 decompress_record(record);
 770                 rc = pstore_mkfile(root, record);
 771                 if (rc) {
 772                         /* pstore_mkfile() did not take record, so free it. */
 773                         kfree(record->buf);
 774                         kfree(record);
 775                         if (rc != -EEXIST || !quiet)
 776                                 failed++;
 777                 }
 778         }
 779         if (psi->close)
 780                 psi->close(psi);
 781 out:
 782         mutex_unlock(&psi->read_mutex);
 783
 784         if (failed)
 785                 pr_warn("failed to create %d record(s) from '%s'\n",
 786                         failed, psi->name);
 787         if (!stop_loop)
 788                 pr_err("looping? Too many records seen from '%s'\n",
 789                         psi->name);
 790 }
 791
 792 static void pstore_dowork(struct work_struct *work)
 793 {
 794         pstore_get_records(1);
 795 }
 796
 797 static void pstore_timefunc(struct timer_list *unused)
 798 {
 799         if (pstore_new_entry) {
 800                 pstore_new_entry = 0;
 801                 schedule_work(&pstore_work);
 802         }
 803
 804         pstore_timer_kick();
 805 }
 806
 807 static void __init pstore_choose_compression(void)
 808 {
 809         const struct pstore_zbackend *step;
 810
 811         if (!compress)
 812                 return;
 813
 814         for (step = zbackends; step->name; step++) {
 815                 if (!strcmp(compress, step->name)) {
 816                         zbackend = step;
 817                         return;
 818                 }
 819         }
 820 }
 821
 822 static int __init pstore_init(void)
 823 {
 824         int ret;
 825
 826         pstore_choose_compression();
 827
 828         /*
 829          * Check if any pstore backends registered earlier but did not
 830          * initialize compression because crypto was not ready. If so,
 831          * initialize compression now.
 832          */
 833         allocate_buf_for_compression();
 834
 835         ret = pstore_init_fs();
 836         if (ret)
 837                 free_buf_for_compression();
 838
 839         return ret;
 840 }
 841 late_initcall(pstore_init);
 842
 843 static void __exit pstore_exit(void)
 844 {
 845         pstore_exit_fs();
 846 }
 847 module_exit(pstore_exit)
 848
 849 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 850 MODULE_LICENSE("GPL");