fs/pstore/platform.c

   1 /*
   2  * Persistent Storage - platform driver interface parts.
   3  *
   4  * Copyright (C) 2007-2008 Google, Inc.
   5  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #define pr_fmt(fmt) "pstore: " fmt
  22
  23 #include <linux/atomic.h>
  24 #include <linux/types.h>
  25 #include <linux/errno.h>
  26 #include <linux/init.h>
  27 #include <linux/kmsg_dump.h>
  28 #include <linux/console.h>
  29 #include <linux/module.h>
  30 #include <linux/pstore.h>
  31 #ifdef CONFIG_PSTORE_ZLIB_COMPRESS
  32 #include <linux/zlib.h>
  33 #endif
  34 #ifdef CONFIG_PSTORE_LZO_COMPRESS
  35 #include <linux/lzo.h>
  36 #endif
  37 #ifdef CONFIG_PSTORE_LZ4_COMPRESS
  38 #include <linux/lz4.h>
  39 #endif
  40 #include <linux/string.h>
  41 #include <linux/timer.h>
  42 #include <linux/slab.h>
  43 #include <linux/uaccess.h>
  44 #include <linux/hardirq.h>
  45 #include <linux/jiffies.h>
  46 #include <linux/workqueue.h>
  47
  48 #include "internal.h"
  49
  50 /*
  51  * We defer making "oops" entries appear in pstore - see
  52  * whether the system is actually still running well enough
  53  * to let someone see the entry
  54  */
  55 static int pstore_update_ms = -1;
  56 module_param_named(update_ms, pstore_update_ms, int, 0600);
  57 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
  58                  "(default is -1, which means runtime updates are disabled; "
  59                  "enabling this option is not safe, it may lead to further "
  60                  "corruption on Oopses)");
  61
  62 static int pstore_new_entry;
  63
  64 static void pstore_timefunc(unsigned long);
  65 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
  66
  67 static void pstore_dowork(struct work_struct *);
  68 static DECLARE_WORK(pstore_work, pstore_dowork);
  69
  70 /*
  71  * pstore_lock just protects "psinfo" during
  72  * calls to pstore_register()
  73  */
  74 static DEFINE_SPINLOCK(pstore_lock);
  75 struct pstore_info *psinfo;
  76
  77 static char *backend;
  78
  79 /* Compression parameters */
  80 #ifdef CONFIG_PSTORE_ZLIB_COMPRESS
  81 #define COMPR_LEVEL 6
  82 #define WINDOW_BITS 12
  83 #define MEM_LEVEL 4
  84 static struct z_stream_s stream;
  85 #else
  86 static unsigned char *workspace;
  87 #endif
  88
  89 struct pstore_zbackend {
  90         int (*compress)(const void *in, void *out, size_t inlen, size_t outlen);
  91         int (*decompress)(void *in, void *out, size_t inlen, size_t outlen);
  92         void (*allocate)(void);
  93         void (*free)(void);
  94
  95         const char *name;
  96 };
  97
  98 static char *big_oops_buf;
  99 static size_t big_oops_buf_sz;
 100
 101 /* How much of the console log to snapshot */
 102 static unsigned long kmsg_bytes = 10240;
 103
 104 void pstore_set_kmsg_bytes(int bytes)
 105 {
 106         kmsg_bytes = bytes;
 107 }
 108
 109 /* Tag each group of saved records with a sequence number */
 110 static int      oopscount;
 111
 112 static const char *get_reason_str(enum kmsg_dump_reason reason)
 113 {
 114         switch (reason) {
 115         case KMSG_DUMP_PANIC:
 116                 return "Panic";
 117         case KMSG_DUMP_OOPS:
 118                 return "Oops";
 119         case KMSG_DUMP_EMERG:
 120                 return "Emergency";
 121         case KMSG_DUMP_RESTART:
 122                 return "Restart";
 123         case KMSG_DUMP_HALT:
 124                 return "Halt";
 125         case KMSG_DUMP_POWEROFF:
 126                 return "Poweroff";
 127         default:
 128                 return "Unknown";
 129         }
 130 }
 131
 132 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 133 {
 134         /*
 135          * In case of NMI path, pstore shouldn't be blocked
 136          * regardless of reason.
 137          */
 138         if (in_nmi())
 139                 return true;
 140
 141         switch (reason) {
 142         /* In panic case, other cpus are stopped by smp_send_stop(). */
 143         case KMSG_DUMP_PANIC:
 144         /* Emergency restart shouldn't be blocked by spin lock. */
 145         case KMSG_DUMP_EMERG:
 146                 return true;
 147         default:
 148                 return false;
 149         }
 150 }
 151 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
 152
 153 #ifdef CONFIG_PSTORE_ZLIB_COMPRESS
 154 /* Derived from logfs_compress() */
 155 static int compress_zlib(const void *in, void *out, size_t inlen, size_t outlen)
 156 {
 157         int err, ret;
 158
 159         ret = -EIO;
 160         err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
 161                                                 MEM_LEVEL, Z_DEFAULT_STRATEGY);
 162         if (err != Z_OK)
 163                 goto error;
 164
 165         stream.next_in = in;
 166         stream.avail_in = inlen;
 167         stream.total_in = 0;
 168         stream.next_out = out;
 169         stream.avail_out = outlen;
 170         stream.total_out = 0;
 171
 172         err = zlib_deflate(&stream, Z_FINISH);
 173         if (err != Z_STREAM_END)
 174                 goto error;
 175
 176         err = zlib_deflateEnd(&stream);
 177         if (err != Z_OK)
 178                 goto error;
 179
 180         if (stream.total_out >= stream.total_in)
 181                 goto error;
 182
 183         ret = stream.total_out;
 184 error:
 185         return ret;
 186 }
 187
 188 /* Derived from logfs_uncompress */
 189 static int decompress_zlib(void *in, void *out, size_t inlen, size_t outlen)
 190 {
 191         int err, ret;
 192
 193         ret = -EIO;
 194         err = zlib_inflateInit2(&stream, WINDOW_BITS);
 195         if (err != Z_OK)
 196                 goto error;
 197
 198         stream.next_in = in;
 199         stream.avail_in = inlen;
 200         stream.total_in = 0;
 201         stream.next_out = out;
 202         stream.avail_out = outlen;
 203         stream.total_out = 0;
 204
 205         err = zlib_inflate(&stream, Z_FINISH);
 206         if (err != Z_STREAM_END)
 207                 goto error;
 208
 209         err = zlib_inflateEnd(&stream);
 210         if (err != Z_OK)
 211                 goto error;
 212
 213         ret = stream.total_out;
 214 error:
 215         return ret;
 216 }
 217
 218 static void allocate_zlib(void)
 219 {
 220         size_t size;
 221         size_t cmpr;
 222
 223         switch (psinfo->bufsize) {
 224         /* buffer range for efivars */
 225         case 1000 ... 2000:
 226                 cmpr = 56;
 227                 break;
 228         case 2001 ... 3000:
 229                 cmpr = 54;
 230                 break;
 231         case 3001 ... 3999:
 232                 cmpr = 52;
 233                 break;
 234         /* buffer range for nvram, erst */
 235         case 4000 ... 10000:
 236                 cmpr = 45;
 237                 break;
 238         default:
 239                 cmpr = 60;
 240                 break;
 241         }
 242
 243         big_oops_buf_sz = (psinfo->bufsize * 100) / cmpr;
 244         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 245         if (big_oops_buf) {
 246                 size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
 247                         zlib_inflate_workspacesize());
 248                 stream.workspace = kmalloc(size, GFP_KERNEL);
 249                 if (!stream.workspace) {
 250                         pr_err("No memory for compression workspace; skipping compression\n");
 251                         kfree(big_oops_buf);
 252                         big_oops_buf = NULL;
 253                 }
 254         } else {
 255                 pr_err("No memory for uncompressed data; skipping compression\n");
 256                 stream.workspace = NULL;
 257         }
 258
 259 }
 260
 261 static void free_zlib(void)
 262 {
 263         kfree(stream.workspace);
 264         stream.workspace = NULL;
 265         kfree(big_oops_buf);
 266         big_oops_buf = NULL;
 267         big_oops_buf_sz = 0;
 268 }
 269
 270 static const struct pstore_zbackend backend_zlib = {
 271         .compress       = compress_zlib,
 272         .decompress     = decompress_zlib,
 273         .allocate       = allocate_zlib,
 274         .free           = free_zlib,
 275         .name           = "zlib",
 276 };
 277 #endif
 278
 279 #ifdef CONFIG_PSTORE_LZO_COMPRESS
 280 static int compress_lzo(const void *in, void *out, size_t inlen, size_t outlen)
 281 {
 282         int ret;
 283
 284         ret = lzo1x_1_compress(in, inlen, out, &outlen, workspace);
 285         if (ret != LZO_E_OK) {
 286                 pr_err("lzo_compress error, ret = %d!\n", ret);
 287                 return -EIO;
 288         }
 289
 290         return outlen;
 291 }
 292
 293 static int decompress_lzo(void *in, void *out, size_t inlen, size_t outlen)
 294 {
 295         int ret;
 296
 297         ret = lzo1x_decompress_safe(in, inlen, out, &outlen);
 298         if (ret != LZO_E_OK) {
 299                 pr_err("lzo_decompress error, ret = %d!\n", ret);
 300                 return -EIO;
 301         }
 302
 303         return outlen;
 304 }
 305
 306 static void allocate_lzo(void)
 307 {
 308         big_oops_buf_sz = lzo1x_worst_compress(psinfo->bufsize);
 309         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 310         if (big_oops_buf) {
 311                 workspace = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 312                 if (!workspace) {
 313                         pr_err("No memory for compression workspace; skipping compression\n");
 314                         kfree(big_oops_buf);
 315                         big_oops_buf = NULL;
 316                 }
 317         } else {
 318                 pr_err("No memory for uncompressed data; skipping compression\n");
 319                 workspace = NULL;
 320         }
 321 }
 322
 323 static void free_lzo(void)
 324 {
 325         kfree(workspace);
 326         kfree(big_oops_buf);
 327         big_oops_buf = NULL;
 328         big_oops_buf_sz = 0;
 329 }
 330
 331 static const struct pstore_zbackend backend_lzo = {
 332         .compress       = compress_lzo,
 333         .decompress     = decompress_lzo,
 334         .allocate       = allocate_lzo,
 335         .free           = free_lzo,
 336         .name           = "lzo",
 337 };
 338 #endif
 339
 340 #ifdef CONFIG_PSTORE_LZ4_COMPRESS
 341 static int compress_lz4(const void *in, void *out, size_t inlen, size_t outlen)
 342 {
 343         int ret;
 344
 345         ret = LZ4_compress_default(in, out, inlen, outlen, workspace);
 346         if (!ret) {
 347                 pr_err("LZ4_compress_default error; compression failed!\n");
 348                 return -EIO;
 349         }
 350
 351         return ret;
 352 }
 353
 354 static int decompress_lz4(void *in, void *out, size_t inlen, size_t outlen)
 355 {
 356         int ret;
 357
 358         ret = LZ4_decompress_safe(in, out, inlen, outlen);
 359         if (ret < 0) {
 360                 /*
 361                  * LZ4_decompress_safe will return an error code
 362                  * (< 0) if decompression failed
 363                  */
 364                 pr_err("LZ4_decompress_safe error, ret = %d!\n", ret);
 365                 return -EIO;
 366         }
 367
 368         return ret;
 369 }
 370
 371 static void allocate_lz4(void)
 372 {
 373         big_oops_buf_sz = LZ4_compressBound(psinfo->bufsize);
 374         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 375         if (big_oops_buf) {
 376                 workspace = kmalloc(LZ4_MEM_COMPRESS, GFP_KERNEL);
 377                 if (!workspace) {
 378                         pr_err("No memory for compression workspace; skipping compression\n");
 379                         kfree(big_oops_buf);
 380                         big_oops_buf = NULL;
 381                 }
 382         } else {
 383                 pr_err("No memory for uncompressed data; skipping compression\n");
 384                 workspace = NULL;
 385         }
 386 }
 387
 388 static void free_lz4(void)
 389 {
 390         kfree(workspace);
 391         kfree(big_oops_buf);
 392         big_oops_buf = NULL;
 393         big_oops_buf_sz = 0;
 394 }
 395
 396 static const struct pstore_zbackend backend_lz4 = {
 397         .compress       = compress_lz4,
 398         .decompress     = decompress_lz4,
 399         .allocate       = allocate_lz4,
 400         .free           = free_lz4,
 401         .name           = "lz4",
 402 };
 403 #endif
 404
 405 static const struct pstore_zbackend *zbackend =
 406 #if defined(CONFIG_PSTORE_ZLIB_COMPRESS)
 407         &backend_zlib;
 408 #elif defined(CONFIG_PSTORE_LZO_COMPRESS)
 409         &backend_lzo;
 410 #elif defined(CONFIG_PSTORE_LZ4_COMPRESS)
 411         &backend_lz4;
 412 #else
 413         NULL;
 414 #endif
 415
 416 static int pstore_compress(const void *in, void *out,
 417                            size_t inlen, size_t outlen)
 418 {
 419         if (zbackend)
 420                 return zbackend->compress(in, out, inlen, outlen);
 421         else
 422                 return -EIO;
 423 }
 424
 425 static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
 426 {
 427         if (zbackend)
 428                 return zbackend->decompress(in, out, inlen, outlen);
 429         else
 430                 return -EIO;
 431 }
 432
 433 static void allocate_buf_for_compression(void)
 434 {
 435         if (zbackend) {
 436                 pr_info("using %s compression\n", zbackend->name);
 437                 zbackend->allocate();
 438         } else {
 439                 pr_err("allocate compression buffer error!\n");
 440         }
 441 }
 442
 443 static void free_buf_for_compression(void)
 444 {
 445         if (zbackend)
 446                 zbackend->free();
 447         else
 448                 pr_err("free compression buffer error!\n");
 449 }
 450
 451 /*
 452  * Called when compression fails, since the printk buffer
 453  * would be fetched for compression calling it again when
 454  * compression fails would have moved the iterator of
 455  * printk buffer which results in fetching old contents.
 456  * Copy the recent messages from big_oops_buf to psinfo->buf
 457  */
 458 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 459 {
 460         size_t total_len;
 461         size_t diff;
 462
 463         total_len = hsize + len;
 464
 465         if (total_len > psinfo->bufsize) {
 466                 diff = total_len - psinfo->bufsize + hsize;
 467                 memcpy(psinfo->buf, big_oops_buf, hsize);
 468                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 469                                         psinfo->bufsize - hsize);
 470                 total_len = psinfo->bufsize;
 471         } else
 472                 memcpy(psinfo->buf, big_oops_buf, total_len);
 473
 474         return total_len;
 475 }
 476
 477 /*
 478  * callback from kmsg_dump. (s2,l2) has the most recently
 479  * written bytes, older bytes are in (s1,l1). Save as much
 480  * as we can from the end of the buffer.
 481  */
 482 static void pstore_dump(struct kmsg_dumper *dumper,
 483                         enum kmsg_dump_reason reason)
 484 {
 485         unsigned long   total = 0;
 486         const char      *why;
 487         unsigned int    part = 1;
 488         unsigned long   flags = 0;
 489         int             is_locked;
 490         int             ret;
 491
 492         why = get_reason_str(reason);
 493
 494         if (pstore_cannot_block_path(reason)) {
 495                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 496                 if (!is_locked) {
 497                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 498                                        , in_nmi() ? "NMI" : why);
 499                         return;
 500                 }
 501         } else {
 502                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 503                 is_locked = 1;
 504         }
 505         oopscount++;
 506         while (total < kmsg_bytes) {
 507                 char *dst;
 508                 size_t dst_size;
 509                 int header_size;
 510                 int zipped_len = -1;
 511                 size_t dump_size;
 512                 struct pstore_record record = {
 513                         .type = PSTORE_TYPE_DMESG,
 514                         .count = oopscount,
 515                         .reason = reason,
 516                         .part = part,
 517                         .compressed = false,
 518                         .buf = psinfo->buf,
 519                         .psi = psinfo,
 520                 };
 521
 522                 if (big_oops_buf && is_locked) {
 523                         dst = big_oops_buf;
 524                         dst_size = big_oops_buf_sz;
 525                 } else {
 526                         dst = psinfo->buf;
 527                         dst_size = psinfo->bufsize;
 528                 }
 529
 530                 /* Write dump header. */
 531                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 532                                  oopscount, part);
 533                 dst_size -= header_size;
 534
 535                 /* Write dump contents. */
 536                 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
 537                                           dst_size, &dump_size))
 538                         break;
 539
 540                 if (big_oops_buf && is_locked) {
 541                         zipped_len = pstore_compress(dst, psinfo->buf,
 542                                                 header_size + dump_size,
 543                                                 psinfo->bufsize);
 544
 545                         if (zipped_len > 0) {
 546                                 record.compressed = true;
 547                                 record.size = zipped_len;
 548                         } else {
 549                                 record.size = copy_kmsg_to_buffer(header_size,
 550                                                                   dump_size);
 551                         }
 552                 } else {
 553                         record.size = header_size + dump_size;
 554                 }
 555
 556                 ret = psinfo->write(&record);
 557                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 558                         pstore_new_entry = 1;
 559
 560                 total += record.size;
 561                 part++;
 562         }
 563         if (is_locked)
 564                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 565 }
 566
 567 static struct kmsg_dumper pstore_dumper = {
 568         .dump = pstore_dump,
 569 };
 570
 571 /*
 572  * Register with kmsg_dump to save last part of console log on panic.
 573  */
 574 static void pstore_register_kmsg(void)
 575 {
 576         kmsg_dump_register(&pstore_dumper);
 577 }
 578
 579 static void pstore_unregister_kmsg(void)
 580 {
 581         kmsg_dump_unregister(&pstore_dumper);
 582 }
 583
 584 #ifdef CONFIG_PSTORE_CONSOLE
 585 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 586 {
 587         const char *e = s + c;
 588
 589         while (s < e) {
 590                 struct pstore_record record = {
 591                         .type = PSTORE_TYPE_CONSOLE,
 592                         .psi = psinfo,
 593                 };
 594                 unsigned long flags;
 595
 596                 if (c > psinfo->bufsize)
 597                         c = psinfo->bufsize;
 598
 599                 if (oops_in_progress) {
 600                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 601                                 break;
 602                 } else {
 603                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 604                 }
 605                 record.buf = (char *)s;
 606                 record.size = c;
 607                 psinfo->write(&record);
 608                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 609                 s += c;
 610                 c = e - s;
 611         }
 612 }
 613
 614 static struct console pstore_console = {
 615         .name   = "pstore",
 616         .write  = pstore_console_write,
 617         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 618         .index  = -1,
 619 };
 620
 621 static void pstore_register_console(void)
 622 {
 623         register_console(&pstore_console);
 624 }
 625
 626 static void pstore_unregister_console(void)
 627 {
 628         unregister_console(&pstore_console);
 629 }
 630 #else
 631 static void pstore_register_console(void) {}
 632 static void pstore_unregister_console(void) {}
 633 #endif
 634
 635 static int pstore_write_user_compat(struct pstore_record *record,
 636                                     const char __user *buf)
 637 {
 638         int ret = 0;
 639
 640         if (record->buf)
 641                 return -EINVAL;
 642
 643         record->buf = kmalloc(record->size, GFP_KERNEL);
 644         if (!record->buf)
 645                 return -ENOMEM;
 646
 647         if (unlikely(copy_from_user(record->buf, buf, record->size))) {
 648                 ret = -EFAULT;
 649                 goto out;
 650         }
 651
 652         ret = record->psi->write(record);
 653
 654 out:
 655         kfree(record->buf);
 656         record->buf = NULL;
 657
 658         return unlikely(ret < 0) ? ret : record->size;
 659 }
 660
 661 /*
 662  * platform specific persistent storage driver registers with
 663  * us here. If pstore is already mounted, call the platform
 664  * read function right away to populate the file system. If not
 665  * then the pstore mount code will call us later to fill out
 666  * the file system.
 667  */
 668 int pstore_register(struct pstore_info *psi)
 669 {
 670         struct module *owner = psi->owner;
 671
 672         if (backend && strcmp(backend, psi->name)) {
 673                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 674                 return -EPERM;
 675         }
 676
 677         /* Sanity check flags. */
 678         if (!psi->flags) {
 679                 pr_warn("backend '%s' must support at least one frontend\n",
 680                         psi->name);
 681                 return -EINVAL;
 682         }
 683
 684         /* Check for required functions. */
 685         if (!psi->read || !psi->write) {
 686                 pr_warn("backend '%s' must implement read() and write()\n",
 687                         psi->name);
 688                 return -EINVAL;
 689         }
 690
 691         spin_lock(&pstore_lock);
 692         if (psinfo) {
 693                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 694                         psinfo->name, psi->name);
 695                 spin_unlock(&pstore_lock);
 696                 return -EBUSY;
 697         }
 698
 699         if (!psi->write_user)
 700                 psi->write_user = pstore_write_user_compat;
 701         psinfo = psi;
 702         mutex_init(&psinfo->read_mutex);
 703         spin_unlock(&pstore_lock);
 704
 705         if (owner && !try_module_get(owner)) {
 706                 psinfo = NULL;
 707                 return -EINVAL;
 708         }
 709
 710         allocate_buf_for_compression();
 711
 712         if (pstore_is_mounted())
 713                 pstore_get_records(0);
 714
 715         if (psi->flags & PSTORE_FLAGS_DMESG)
 716                 pstore_register_kmsg();
 717         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 718                 pstore_register_console();
 719         if (psi->flags & PSTORE_FLAGS_FTRACE)
 720                 pstore_register_ftrace();
 721         if (psi->flags & PSTORE_FLAGS_PMSG)
 722                 pstore_register_pmsg();
 723
 724         /* Start watching for new records, if desired. */
 725         if (pstore_update_ms >= 0) {
 726                 pstore_timer.expires = jiffies +
 727                         msecs_to_jiffies(pstore_update_ms);
 728                 add_timer(&pstore_timer);
 729         }
 730
 731         /*
 732          * Update the module parameter backend, so it is visible
 733          * through /sys/module/pstore/parameters/backend
 734          */
 735         backend = psi->name;
 736
 737         pr_info("Registered %s as persistent store backend\n", psi->name);
 738
 739         module_put(owner);
 740
 741         return 0;
 742 }
 743 EXPORT_SYMBOL_GPL(pstore_register);
 744
 745 void pstore_unregister(struct pstore_info *psi)
 746 {
 747         /* Stop timer and make sure all work has finished. */
 748         pstore_update_ms = -1;
 749         del_timer_sync(&pstore_timer);
 750         flush_work(&pstore_work);
 751
 752         if (psi->flags & PSTORE_FLAGS_PMSG)
 753                 pstore_unregister_pmsg();
 754         if (psi->flags & PSTORE_FLAGS_FTRACE)
 755                 pstore_unregister_ftrace();
 756         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 757                 pstore_unregister_console();
 758         if (psi->flags & PSTORE_FLAGS_DMESG)
 759                 pstore_unregister_kmsg();
 760
 761         free_buf_for_compression();
 762
 763         psinfo = NULL;
 764         backend = NULL;
 765 }
 766 EXPORT_SYMBOL_GPL(pstore_unregister);
 767
 768 static void decompress_record(struct pstore_record *record)
 769 {
 770         int unzipped_len;
 771         char *decompressed;
 772
 773         /* Only PSTORE_TYPE_DMESG support compression. */
 774         if (!record->compressed || record->type != PSTORE_TYPE_DMESG) {
 775                 pr_warn("ignored compressed record type %d\n", record->type);
 776                 return;
 777         }
 778
 779         /* No compression method has created the common buffer. */
 780         if (!big_oops_buf) {
 781                 pr_warn("no decompression buffer allocated\n");
 782                 return;
 783         }
 784
 785         unzipped_len = pstore_decompress(record->buf, big_oops_buf,
 786                                          record->size, big_oops_buf_sz);
 787         if (unzipped_len <= 0) {
 788                 pr_err("decompression failed: %d\n", unzipped_len);
 789                 return;
 790         }
 791
 792         /* Build new buffer for decompressed contents. */
 793         decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
 794                                GFP_KERNEL);
 795         if (!decompressed) {
 796                 pr_err("decompression ran out of memory\n");
 797                 return;
 798         }
 799         memcpy(decompressed, big_oops_buf, unzipped_len);
 800
 801         /* Append ECC notice to decompressed buffer. */
 802         memcpy(decompressed + unzipped_len, record->buf + record->size,
 803                record->ecc_notice_size);
 804
 805         /* Swap out compresed contents with decompressed contents. */
 806         kfree(record->buf);
 807         record->buf = decompressed;
 808         record->size = unzipped_len;
 809         record->compressed = false;
 810 }
 811
 812 /*
 813  * Read all the records from one persistent store backend. Create
 814  * files in our filesystem.  Don't warn about -EEXIST errors
 815  * when we are re-scanning the backing store looking to add new
 816  * error records.
 817  */
 818 void pstore_get_backend_records(struct pstore_info *psi,
 819                                 struct dentry *root, int quiet)
 820 {
 821         int failed = 0;
 822
 823         if (!psi || !root)
 824                 return;
 825
 826         mutex_lock(&psi->read_mutex);
 827         if (psi->open && psi->open(psi))
 828                 goto out;
 829
 830         /*
 831          * Backend callback read() allocates record.buf. decompress_record()
 832          * may reallocate record.buf. On success, pstore_mkfile() will keep
 833          * the record.buf, so free it only on failure.
 834          */
 835         for (;;) {
 836                 struct pstore_record *record;
 837                 int rc;
 838
 839                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 840                 if (!record) {
 841                         pr_err("out of memory creating record\n");
 842                         break;
 843                 }
 844                 record->psi = psi;
 845
 846                 record->size = psi->read(record);
 847
 848                 /* No more records left in backend? */
 849                 if (record->size <= 0)
 850                         break;
 851
 852                 decompress_record(record);
 853                 rc = pstore_mkfile(root, record);
 854                 if (rc) {
 855                         /* pstore_mkfile() did not take record, so free it. */
 856                         kfree(record->buf);
 857                         kfree(record);
 858                         if (rc != -EEXIST || !quiet)
 859                                 failed++;
 860                 }
 861         }
 862         if (psi->close)
 863                 psi->close(psi);
 864 out:
 865         mutex_unlock(&psi->read_mutex);
 866
 867         if (failed)
 868                 pr_warn("failed to load %d record(s) from '%s'\n",
 869                         failed, psi->name);
 870 }
 871
 872 static void pstore_dowork(struct work_struct *work)
 873 {
 874         pstore_get_records(1);
 875 }
 876
 877 static void pstore_timefunc(unsigned long dummy)
 878 {
 879         if (pstore_new_entry) {
 880                 pstore_new_entry = 0;
 881                 schedule_work(&pstore_work);
 882         }
 883
 884         if (pstore_update_ms >= 0)
 885                 mod_timer(&pstore_timer,
 886                           jiffies + msecs_to_jiffies(pstore_update_ms));
 887 }
 888
 889 module_param(backend, charp, 0444);
 890 MODULE_PARM_DESC(backend, "Pstore backend to use");