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 /* How much of the kernel log to snapshot */
  93 unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
  94 module_param(kmsg_bytes, ulong, 0444);
  95 MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)");
  96
  97 /* Compression parameters */
  98 static struct crypto_comp *tfm;
  99
 100 struct pstore_zbackend {
 101         int (*zbufsize)(size_t size);
 102         const char *name;
 103 };
 104
 105 static char *big_oops_buf;
 106 static size_t big_oops_buf_sz;
 107
 108 void pstore_set_kmsg_bytes(int bytes)
 109 {
 110         kmsg_bytes = bytes;
 111 }
 112
 113 /* Tag each group of saved records with a sequence number */
 114 static int      oopscount;
 115
 116 const char *pstore_type_to_name(enum pstore_type_id type)
 117 {
 118         BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
 119
 120         if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
 121                 return "unknown";
 122
 123         return pstore_type_names[type];
 124 }
 125 EXPORT_SYMBOL_GPL(pstore_type_to_name);
 126
 127 enum pstore_type_id pstore_name_to_type(const char *name)
 128 {
 129         int i;
 130
 131         for (i = 0; i < PSTORE_TYPE_MAX; i++) {
 132                 if (!strcmp(pstore_type_names[i], name))
 133                         return i;
 134         }
 135
 136         return PSTORE_TYPE_MAX;
 137 }
 138 EXPORT_SYMBOL_GPL(pstore_name_to_type);
 139
 140 static void pstore_timer_kick(void)
 141 {
 142         if (pstore_update_ms < 0)
 143                 return;
 144
 145         mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 146 }
 147
 148 static bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 149 {
 150         /*
 151          * In case of NMI path, pstore shouldn't be blocked
 152          * regardless of reason.
 153          */
 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         /*
 161          * Emergency restart shouldn't be blocked by spinning on
 162          * pstore_info::buf_lock.
 163          */
 164         case KMSG_DUMP_EMERG:
 165                 return true;
 166         default:
 167                 return false;
 168         }
 169 }
 170
 171 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 172 static int zbufsize_deflate(size_t size)
 173 {
 174         size_t cmpr;
 175
 176         switch (size) {
 177         /* buffer range for efivars */
 178         case 1000 ... 2000:
 179                 cmpr = 56;
 180                 break;
 181         case 2001 ... 3000:
 182                 cmpr = 54;
 183                 break;
 184         case 3001 ... 3999:
 185                 cmpr = 52;
 186                 break;
 187         /* buffer range for nvram, erst */
 188         case 4000 ... 10000:
 189                 cmpr = 45;
 190                 break;
 191         default:
 192                 cmpr = 60;
 193                 break;
 194         }
 195
 196         return (size * 100) / cmpr;
 197 }
 198 #endif
 199
 200 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 201 static int zbufsize_lzo(size_t size)
 202 {
 203         return lzo1x_worst_compress(size);
 204 }
 205 #endif
 206
 207 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 208 static int zbufsize_lz4(size_t size)
 209 {
 210         return LZ4_compressBound(size);
 211 }
 212 #endif
 213
 214 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 215 static int zbufsize_842(size_t size)
 216 {
 217         return size;
 218 }
 219 #endif
 220
 221 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 222 static int zbufsize_zstd(size_t size)
 223 {
 224         return zstd_compress_bound(size);
 225 }
 226 #endif
 227
 228 static const struct pstore_zbackend *zbackend __ro_after_init;
 229
 230 static const struct pstore_zbackend zbackends[] = {
 231 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 232         {
 233                 .zbufsize       = zbufsize_deflate,
 234                 .name           = "deflate",
 235         },
 236 #endif
 237 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 238         {
 239                 .zbufsize       = zbufsize_lzo,
 240                 .name           = "lzo",
 241         },
 242 #endif
 243 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
 244         {
 245                 .zbufsize       = zbufsize_lz4,
 246                 .name           = "lz4",
 247         },
 248 #endif
 249 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 250         {
 251                 .zbufsize       = zbufsize_lz4,
 252                 .name           = "lz4hc",
 253         },
 254 #endif
 255 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 256         {
 257                 .zbufsize       = zbufsize_842,
 258                 .name           = "842",
 259         },
 260 #endif
 261 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 262         {
 263                 .zbufsize       = zbufsize_zstd,
 264                 .name           = "zstd",
 265         },
 266 #endif
 267         { }
 268 };
 269
 270 static int pstore_compress(const void *in, void *out,
 271                            unsigned int inlen, unsigned int outlen)
 272 {
 273         int ret;
 274
 275         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
 276                 return -EINVAL;
 277
 278         ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
 279         if (ret) {
 280                 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
 281                 return ret;
 282         }
 283
 284         return outlen;
 285 }
 286
 287 static void allocate_buf_for_compression(void)
 288 {
 289         struct crypto_comp *ctx;
 290         int size;
 291         char *buf;
 292
 293         /* Skip if not built-in or compression backend not selected yet. */
 294         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
 295                 return;
 296
 297         /* Skip if no pstore backend yet or compression init already done. */
 298         if (!psinfo || tfm)
 299                 return;
 300
 301         if (!crypto_has_comp(zbackend->name, 0, 0)) {
 302                 pr_err("Unknown compression: %s\n", zbackend->name);
 303                 return;
 304         }
 305
 306         size = zbackend->zbufsize(psinfo->bufsize);
 307         if (size <= 0) {
 308                 pr_err("Invalid compression size for %s: %d\n",
 309                        zbackend->name, size);
 310                 return;
 311         }
 312
 313         buf = kmalloc(size, GFP_KERNEL);
 314         if (!buf) {
 315                 pr_err("Failed %d byte compression buffer allocation for: %s\n",
 316                        size, zbackend->name);
 317                 return;
 318         }
 319
 320         ctx = crypto_alloc_comp(zbackend->name, 0, 0);
 321         if (IS_ERR_OR_NULL(ctx)) {
 322                 kfree(buf);
 323                 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
 324                        PTR_ERR(ctx));
 325                 return;
 326         }
 327
 328         /* A non-NULL big_oops_buf indicates compression is available. */
 329         tfm = ctx;
 330         big_oops_buf_sz = size;
 331         big_oops_buf = buf;
 332
 333         pr_info("Using crash dump compression: %s\n", zbackend->name);
 334 }
 335
 336 static void free_buf_for_compression(void)
 337 {
 338         if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
 339                 crypto_free_comp(tfm);
 340                 tfm = NULL;
 341         }
 342         kfree(big_oops_buf);
 343         big_oops_buf = NULL;
 344         big_oops_buf_sz = 0;
 345 }
 346
 347 /*
 348  * Called when compression fails, since the printk buffer
 349  * would be fetched for compression calling it again when
 350  * compression fails would have moved the iterator of
 351  * printk buffer which results in fetching old contents.
 352  * Copy the recent messages from big_oops_buf to psinfo->buf
 353  */
 354 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 355 {
 356         size_t total_len;
 357         size_t diff;
 358
 359         total_len = hsize + len;
 360
 361         if (total_len > psinfo->bufsize) {
 362                 diff = total_len - psinfo->bufsize + hsize;
 363                 memcpy(psinfo->buf, big_oops_buf, hsize);
 364                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 365                                         psinfo->bufsize - hsize);
 366                 total_len = psinfo->bufsize;
 367         } else
 368                 memcpy(psinfo->buf, big_oops_buf, total_len);
 369
 370         return total_len;
 371 }
 372
 373 void pstore_record_init(struct pstore_record *record,
 374                         struct pstore_info *psinfo)
 375 {
 376         memset(record, 0, sizeof(*record));
 377
 378         record->psi = psinfo;
 379
 380         /* Report zeroed timestamp if called before timekeeping has resumed. */
 381         record->time = ns_to_timespec64(ktime_get_real_fast_ns());
 382 }
 383
 384 /*
 385  * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
 386  * end of the buffer.
 387  */
 388 static void pstore_dump(struct kmsg_dumper *dumper,
 389                         enum kmsg_dump_reason reason)
 390 {
 391         struct kmsg_dump_iter iter;
 392         unsigned long   total = 0;
 393         const char      *why;
 394         unsigned int    part = 1;
 395         unsigned long   flags = 0;
 396         int             saved_ret = 0;
 397         int             ret;
 398
 399         why = kmsg_dump_reason_str(reason);
 400
 401         if (pstore_cannot_block_path(reason)) {
 402                 if (!spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
 403                         pr_err("dump skipped in %s path because of concurrent dump\n",
 404                                         in_nmi() ? "NMI" : why);
 405                         return;
 406                 }
 407         } else {
 408                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 409         }
 410
 411         kmsg_dump_rewind(&iter);
 412
 413         oopscount++;
 414         while (total < kmsg_bytes) {
 415                 char *dst;
 416                 size_t dst_size;
 417                 int header_size;
 418                 int zipped_len = -1;
 419                 size_t dump_size;
 420                 struct pstore_record record;
 421
 422                 pstore_record_init(&record, psinfo);
 423                 record.type = PSTORE_TYPE_DMESG;
 424                 record.count = oopscount;
 425                 record.reason = reason;
 426                 record.part = part;
 427                 record.buf = psinfo->buf;
 428
 429                 if (big_oops_buf) {
 430                         dst = big_oops_buf;
 431                         dst_size = big_oops_buf_sz;
 432                 } else {
 433                         dst = psinfo->buf;
 434                         dst_size = psinfo->bufsize;
 435                 }
 436
 437                 /* Write dump header. */
 438                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 439                                  oopscount, part);
 440                 dst_size -= header_size;
 441
 442                 /* Write dump contents. */
 443                 if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
 444                                           dst_size, &dump_size))
 445                         break;
 446
 447                 if (big_oops_buf) {
 448                         zipped_len = pstore_compress(dst, psinfo->buf,
 449                                                 header_size + dump_size,
 450                                                 psinfo->bufsize);
 451
 452                         if (zipped_len > 0) {
 453                                 record.compressed = true;
 454                                 record.size = zipped_len;
 455                         } else {
 456                                 record.size = copy_kmsg_to_buffer(header_size,
 457                                                                   dump_size);
 458                         }
 459                 } else {
 460                         record.size = header_size + dump_size;
 461                 }
 462
 463                 ret = psinfo->write(&record);
 464                 if (ret == 0 && reason == KMSG_DUMP_OOPS) {
 465                         pstore_new_entry = 1;
 466                         pstore_timer_kick();
 467                 } else {
 468                         /* Preserve only the first non-zero returned value. */
 469                         if (!saved_ret)
 470                                 saved_ret = ret;
 471                 }
 472
 473                 total += record.size;
 474                 part++;
 475         }
 476         spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 477
 478         if (saved_ret) {
 479                 pr_err_once("backend (%s) writing error (%d)\n", psinfo->name,
 480                             saved_ret);
 481         }
 482 }
 483
 484 static struct kmsg_dumper pstore_dumper = {
 485         .dump = pstore_dump,
 486 };
 487
 488 /*
 489  * Register with kmsg_dump to save last part of console log on panic.
 490  */
 491 static void pstore_register_kmsg(void)
 492 {
 493         kmsg_dump_register(&pstore_dumper);
 494 }
 495
 496 static void pstore_unregister_kmsg(void)
 497 {
 498         kmsg_dump_unregister(&pstore_dumper);
 499 }
 500
 501 #ifdef CONFIG_PSTORE_CONSOLE
 502 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 503 {
 504         struct pstore_record record;
 505
 506         if (!c)
 507                 return;
 508
 509         pstore_record_init(&record, psinfo);
 510         record.type = PSTORE_TYPE_CONSOLE;
 511
 512         record.buf = (char *)s;
 513         record.size = c;
 514         psinfo->write(&record);
 515 }
 516
 517 static struct console pstore_console = {
 518         .write  = pstore_console_write,
 519         .index  = -1,
 520 };
 521
 522 static void pstore_register_console(void)
 523 {
 524         /* Show which backend is going to get console writes. */
 525         strscpy(pstore_console.name, psinfo->name,
 526                 sizeof(pstore_console.name));
 527         /*
 528          * Always initialize flags here since prior unregister_console()
 529          * calls may have changed settings (specifically CON_ENABLED).
 530          */
 531         pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
 532         register_console(&pstore_console);
 533 }
 534
 535 static void pstore_unregister_console(void)
 536 {
 537         unregister_console(&pstore_console);
 538 }
 539 #else
 540 static void pstore_register_console(void) {}
 541 static void pstore_unregister_console(void) {}
 542 #endif
 543
 544 static int pstore_write_user_compat(struct pstore_record *record,
 545                                     const char __user *buf)
 546 {
 547         int ret = 0;
 548
 549         if (record->buf)
 550                 return -EINVAL;
 551
 552         record->buf = memdup_user(buf, record->size);
 553         if (IS_ERR(record->buf)) {
 554                 ret = PTR_ERR(record->buf);
 555                 goto out;
 556         }
 557
 558         ret = record->psi->write(record);
 559
 560         kfree(record->buf);
 561 out:
 562         record->buf = NULL;
 563
 564         return unlikely(ret < 0) ? ret : record->size;
 565 }
 566
 567 /*
 568  * platform specific persistent storage driver registers with
 569  * us here. If pstore is already mounted, call the platform
 570  * read function right away to populate the file system. If not
 571  * then the pstore mount code will call us later to fill out
 572  * the file system.
 573  */
 574 int pstore_register(struct pstore_info *psi)
 575 {
 576         if (backend && strcmp(backend, psi->name)) {
 577                 pr_warn("backend '%s' already in use: ignoring '%s'\n",
 578                         backend, psi->name);
 579                 return -EBUSY;
 580         }
 581
 582         /* Sanity check flags. */
 583         if (!psi->flags) {
 584                 pr_warn("backend '%s' must support at least one frontend\n",
 585                         psi->name);
 586                 return -EINVAL;
 587         }
 588
 589         /* Check for required functions. */
 590         if (!psi->read || !psi->write) {
 591                 pr_warn("backend '%s' must implement read() and write()\n",
 592                         psi->name);
 593                 return -EINVAL;
 594         }
 595
 596         mutex_lock(&psinfo_lock);
 597         if (psinfo) {
 598                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 599                         psinfo->name, psi->name);
 600                 mutex_unlock(&psinfo_lock);
 601                 return -EBUSY;
 602         }
 603
 604         if (!psi->write_user)
 605                 psi->write_user = pstore_write_user_compat;
 606         psinfo = psi;
 607         mutex_init(&psinfo->read_mutex);
 608         spin_lock_init(&psinfo->buf_lock);
 609
 610         if (psi->flags & PSTORE_FLAGS_DMESG)
 611                 allocate_buf_for_compression();
 612
 613         pstore_get_records(0);
 614
 615         if (psi->flags & PSTORE_FLAGS_DMESG) {
 616                 pstore_dumper.max_reason = psinfo->max_reason;
 617                 pstore_register_kmsg();
 618         }
 619         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 620                 pstore_register_console();
 621         if (psi->flags & PSTORE_FLAGS_FTRACE)
 622                 pstore_register_ftrace();
 623         if (psi->flags & PSTORE_FLAGS_PMSG)
 624                 pstore_register_pmsg();
 625
 626         /* Start watching for new records, if desired. */
 627         pstore_timer_kick();
 628
 629         /*
 630          * Update the module parameter backend, so it is visible
 631          * through /sys/module/pstore/parameters/backend
 632          */
 633         backend = kstrdup(psi->name, GFP_KERNEL);
 634
 635         pr_info("Registered %s as persistent store backend\n", psi->name);
 636
 637         mutex_unlock(&psinfo_lock);
 638         return 0;
 639 }
 640 EXPORT_SYMBOL_GPL(pstore_register);
 641
 642 void pstore_unregister(struct pstore_info *psi)
 643 {
 644         /* It's okay to unregister nothing. */
 645         if (!psi)
 646                 return;
 647
 648         mutex_lock(&psinfo_lock);
 649
 650         /* Only one backend can be registered at a time. */
 651         if (WARN_ON(psi != psinfo)) {
 652                 mutex_unlock(&psinfo_lock);
 653                 return;
 654         }
 655
 656         /* Unregister all callbacks. */
 657         if (psi->flags & PSTORE_FLAGS_PMSG)
 658                 pstore_unregister_pmsg();
 659         if (psi->flags & PSTORE_FLAGS_FTRACE)
 660                 pstore_unregister_ftrace();
 661         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 662                 pstore_unregister_console();
 663         if (psi->flags & PSTORE_FLAGS_DMESG)
 664                 pstore_unregister_kmsg();
 665
 666         /* Stop timer and make sure all work has finished. */
 667         del_timer_sync(&pstore_timer);
 668         flush_work(&pstore_work);
 669
 670         /* Remove all backend records from filesystem tree. */
 671         pstore_put_backend_records(psi);
 672
 673         free_buf_for_compression();
 674
 675         psinfo = NULL;
 676         kfree(backend);
 677         backend = NULL;
 678
 679         pr_info("Unregistered %s as persistent store backend\n", psi->name);
 680         mutex_unlock(&psinfo_lock);
 681 }
 682 EXPORT_SYMBOL_GPL(pstore_unregister);
 683
 684 static void decompress_record(struct pstore_record *record)
 685 {
 686         int ret;
 687         int unzipped_len;
 688         char *unzipped, *workspace;
 689
 690         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
 691                 return;
 692
 693         /* Only PSTORE_TYPE_DMESG support compression. */
 694         if (record->type != PSTORE_TYPE_DMESG) {
 695                 pr_warn("ignored compressed record type %d\n", record->type);
 696                 return;
 697         }
 698
 699         /* Missing compression buffer means compression was not initialized. */
 700         if (!big_oops_buf) {
 701                 pr_warn("no decompression method initialized!\n");
 702                 return;
 703         }
 704
 705         /* Allocate enough space to hold max decompression and ECC. */
 706         unzipped_len = big_oops_buf_sz;
 707         workspace = kmalloc(unzipped_len + record->ecc_notice_size,
 708                             GFP_KERNEL);
 709         if (!workspace)
 710                 return;
 711
 712         /* After decompression "unzipped_len" is almost certainly smaller. */
 713         ret = crypto_comp_decompress(tfm, record->buf, record->size,
 714                                           workspace, &unzipped_len);
 715         if (ret) {
 716                 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
 717                 kfree(workspace);
 718                 return;
 719         }
 720
 721         /* Append ECC notice to decompressed buffer. */
 722         memcpy(workspace + unzipped_len, record->buf + record->size,
 723                record->ecc_notice_size);
 724
 725         /* Copy decompressed contents into an minimum-sized allocation. */
 726         unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
 727                            GFP_KERNEL);
 728         kfree(workspace);
 729         if (!unzipped)
 730                 return;
 731
 732         /* Swap out compressed contents with decompressed contents. */
 733         kfree(record->buf);
 734         record->buf = unzipped;
 735         record->size = unzipped_len;
 736         record->compressed = false;
 737 }
 738
 739 /*
 740  * Read all the records from one persistent store backend. Create
 741  * files in our filesystem.  Don't warn about -EEXIST errors
 742  * when we are re-scanning the backing store looking to add new
 743  * error records.
 744  */
 745 void pstore_get_backend_records(struct pstore_info *psi,
 746                                 struct dentry *root, int quiet)
 747 {
 748         int failed = 0;
 749         unsigned int stop_loop = 65536;
 750
 751         if (!psi || !root)
 752                 return;
 753
 754         mutex_lock(&psi->read_mutex);
 755         if (psi->open && psi->open(psi))
 756                 goto out;
 757
 758         /*
 759          * Backend callback read() allocates record.buf. decompress_record()
 760          * may reallocate record.buf. On success, pstore_mkfile() will keep
 761          * the record.buf, so free it only on failure.
 762          */
 763         for (; stop_loop; stop_loop--) {
 764                 struct pstore_record *record;
 765                 int rc;
 766
 767                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 768                 if (!record) {
 769                         pr_err("out of memory creating record\n");
 770                         break;
 771                 }
 772                 pstore_record_init(record, psi);
 773
 774                 record->size = psi->read(record);
 775
 776                 /* No more records left in backend? */
 777                 if (record->size <= 0) {
 778                         kfree(record);
 779                         break;
 780                 }
 781
 782                 decompress_record(record);
 783                 rc = pstore_mkfile(root, record);
 784                 if (rc) {
 785                         /* pstore_mkfile() did not take record, so free it. */
 786                         kfree(record->buf);
 787                         kfree(record->priv);
 788                         kfree(record);
 789                         if (rc != -EEXIST || !quiet)
 790                                 failed++;
 791                 }
 792         }
 793         if (psi->close)
 794                 psi->close(psi);
 795 out:
 796         mutex_unlock(&psi->read_mutex);
 797
 798         if (failed)
 799                 pr_warn("failed to create %d record(s) from '%s'\n",
 800                         failed, psi->name);
 801         if (!stop_loop)
 802                 pr_err("looping? Too many records seen from '%s'\n",
 803                         psi->name);
 804 }
 805
 806 static void pstore_dowork(struct work_struct *work)
 807 {
 808         pstore_get_records(1);
 809 }
 810
 811 static void pstore_timefunc(struct timer_list *unused)
 812 {
 813         if (pstore_new_entry) {
 814                 pstore_new_entry = 0;
 815                 schedule_work(&pstore_work);
 816         }
 817
 818         pstore_timer_kick();
 819 }
 820
 821 static void __init pstore_choose_compression(void)
 822 {
 823         const struct pstore_zbackend *step;
 824
 825         if (!compress)
 826                 return;
 827
 828         for (step = zbackends; step->name; step++) {
 829                 if (!strcmp(compress, step->name)) {
 830                         zbackend = step;
 831                         return;
 832                 }
 833         }
 834 }
 835
 836 static int __init pstore_init(void)
 837 {
 838         int ret;
 839
 840         pstore_choose_compression();
 841
 842         /*
 843          * Check if any pstore backends registered earlier but did not
 844          * initialize compression because crypto was not ready. If so,
 845          * initialize compression now.
 846          */
 847         allocate_buf_for_compression();
 848
 849         ret = pstore_init_fs();
 850         if (ret)
 851                 free_buf_for_compression();
 852
 853         return ret;
 854 }
 855 late_initcall(pstore_init);
 856
 857 static void __exit pstore_exit(void)
 858 {
 859         pstore_exit_fs();
 860 }
 861 module_exit(pstore_exit)
 862
 863 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 864 MODULE_LICENSE("GPL");