kernel/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 #include <linux/zlib.h>
  32 #include <linux/string.h>
  33 #include <linux/timer.h>
  34 #include <linux/slab.h>
  35 #include <linux/uaccess.h>
  36 #include <linux/hardirq.h>
  37 #include <linux/jiffies.h>
  38 #include <linux/workqueue.h>
  39
  40 #include "internal.h"
  41
  42 /*
  43  * We defer making "oops" entries appear in pstore - see
  44  * whether the system is actually still running well enough
  45  * to let someone see the entry
  46  */
  47 static int pstore_update_ms = -1;
  48 module_param_named(update_ms, pstore_update_ms, int, 0600);
  49 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
  50                  "(default is -1, which means runtime updates are disabled; "
  51                  "enabling this option is not safe, it may lead to further "
  52                  "corruption on Oopses)");
  53
  54 static int pstore_new_entry;
  55
  56 static void pstore_timefunc(unsigned long);
  57 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
  58
  59 static void pstore_dowork(struct work_struct *);
  60 static DECLARE_WORK(pstore_work, pstore_dowork);
  61
  62 /*
  63  * pstore_lock just protects "psinfo" during
  64  * calls to pstore_register()
  65  */
  66 static DEFINE_SPINLOCK(pstore_lock);
  67 struct pstore_info *psinfo;
  68
  69 static char *backend;
  70
  71 /* Compression parameters */
  72 #define COMPR_LEVEL 6
  73 #define WINDOW_BITS 12
  74 #define MEM_LEVEL 4
  75 static struct z_stream_s stream;
  76
  77 static char *big_oops_buf;
  78 static size_t big_oops_buf_sz;
  79
  80 /* How much of the console log to snapshot */
  81 static unsigned long kmsg_bytes = 10240;
  82
  83 void pstore_set_kmsg_bytes(int bytes)
  84 {
  85         kmsg_bytes = bytes;
  86 }
  87
  88 /* Tag each group of saved records with a sequence number */
  89 static int      oopscount;
  90
  91 static const char *get_reason_str(enum kmsg_dump_reason reason)
  92 {
  93         switch (reason) {
  94         case KMSG_DUMP_PANIC:
  95                 return "Panic";
  96         case KMSG_DUMP_OOPS:
  97                 return "Oops";
  98         case KMSG_DUMP_EMERG:
  99                 return "Emergency";
 100         case KMSG_DUMP_RESTART:
 101                 return "Restart";
 102         case KMSG_DUMP_HALT:
 103                 return "Halt";
 104         case KMSG_DUMP_POWEROFF:
 105                 return "Poweroff";
 106         default:
 107                 return "Unknown";
 108         }
 109 }
 110
 111 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 112 {
 113         /*
 114          * In case of NMI path, pstore shouldn't be blocked
 115          * regardless of reason.
 116          */
 117         if (in_nmi())
 118                 return true;
 119
 120         switch (reason) {
 121         /* In panic case, other cpus are stopped by smp_send_stop(). */
 122         case KMSG_DUMP_PANIC:
 123         /* Emergency restart shouldn't be blocked by spin lock. */
 124         case KMSG_DUMP_EMERG:
 125                 return true;
 126         default:
 127                 return false;
 128         }
 129 }
 130 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
 131
 132 /* Derived from logfs_compress() */
 133 static int pstore_compress(const void *in, void *out, size_t inlen,
 134                                                         size_t outlen)
 135 {
 136         int err, ret;
 137
 138         ret = -EIO;
 139         err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
 140                                                 MEM_LEVEL, Z_DEFAULT_STRATEGY);
 141         if (err != Z_OK)
 142                 goto error;
 143
 144         stream.next_in = in;
 145         stream.avail_in = inlen;
 146         stream.total_in = 0;
 147         stream.next_out = out;
 148         stream.avail_out = outlen;
 149         stream.total_out = 0;
 150
 151         err = zlib_deflate(&stream, Z_FINISH);
 152         if (err != Z_STREAM_END)
 153                 goto error;
 154
 155         err = zlib_deflateEnd(&stream);
 156         if (err != Z_OK)
 157                 goto error;
 158
 159         if (stream.total_out >= stream.total_in)
 160                 goto error;
 161
 162         ret = stream.total_out;
 163 error:
 164         return ret;
 165 }
 166
 167 /* Derived from logfs_uncompress */
 168 static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
 169 {
 170         int err, ret;
 171
 172         ret = -EIO;
 173         err = zlib_inflateInit2(&stream, WINDOW_BITS);
 174         if (err != Z_OK)
 175                 goto error;
 176
 177         stream.next_in = in;
 178         stream.avail_in = inlen;
 179         stream.total_in = 0;
 180         stream.next_out = out;
 181         stream.avail_out = outlen;
 182         stream.total_out = 0;
 183
 184         err = zlib_inflate(&stream, Z_FINISH);
 185         if (err != Z_STREAM_END)
 186                 goto error;
 187
 188         err = zlib_inflateEnd(&stream);
 189         if (err != Z_OK)
 190                 goto error;
 191
 192         ret = stream.total_out;
 193 error:
 194         return ret;
 195 }
 196
 197 static void allocate_buf_for_compression(void)
 198 {
 199         size_t size;
 200         size_t cmpr;
 201
 202         switch (psinfo->bufsize) {
 203         /* buffer range for efivars */
 204         case 1000 ... 2000:
 205                 cmpr = 56;
 206                 break;
 207         case 2001 ... 3000:
 208                 cmpr = 54;
 209                 break;
 210         case 3001 ... 3999:
 211                 cmpr = 52;
 212                 break;
 213         /* buffer range for nvram, erst */
 214         case 4000 ... 10000:
 215                 cmpr = 45;
 216                 break;
 217         default:
 218                 cmpr = 60;
 219                 break;
 220         }
 221
 222         big_oops_buf_sz = (psinfo->bufsize * 100) / cmpr;
 223         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 224         if (big_oops_buf) {
 225                 size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
 226                         zlib_inflate_workspacesize());
 227                 stream.workspace = kmalloc(size, GFP_KERNEL);
 228                 if (!stream.workspace) {
 229                         pr_err("No memory for compression workspace; skipping compression\n");
 230                         kfree(big_oops_buf);
 231                         big_oops_buf = NULL;
 232                 }
 233         } else {
 234                 pr_err("No memory for uncompressed data; skipping compression\n");
 235                 stream.workspace = NULL;
 236         }
 237
 238 }
 239
 240 /*
 241  * Called when compression fails, since the printk buffer
 242  * would be fetched for compression calling it again when
 243  * compression fails would have moved the iterator of
 244  * printk buffer which results in fetching old contents.
 245  * Copy the recent messages from big_oops_buf to psinfo->buf
 246  */
 247 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 248 {
 249         size_t total_len;
 250         size_t diff;
 251
 252         total_len = hsize + len;
 253
 254         if (total_len > psinfo->bufsize) {
 255                 diff = total_len - psinfo->bufsize + hsize;
 256                 memcpy(psinfo->buf, big_oops_buf, hsize);
 257                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 258                                         psinfo->bufsize - hsize);
 259                 total_len = psinfo->bufsize;
 260         } else
 261                 memcpy(psinfo->buf, big_oops_buf, total_len);
 262
 263         return total_len;
 264 }
 265
 266 /*
 267  * callback from kmsg_dump. (s2,l2) has the most recently
 268  * written bytes, older bytes are in (s1,l1). Save as much
 269  * as we can from the end of the buffer.
 270  */
 271 static void pstore_dump(struct kmsg_dumper *dumper,
 272                         enum kmsg_dump_reason reason)
 273 {
 274         unsigned long   total = 0;
 275         const char      *why;
 276         u64             id;
 277         unsigned int    part = 1;
 278         unsigned long   flags = 0;
 279         int             is_locked = 0;
 280         int             ret;
 281
 282         why = get_reason_str(reason);
 283
 284         if (pstore_cannot_block_path(reason)) {
 285                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 286                 if (!is_locked) {
 287                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 288                                        , in_nmi() ? "NMI" : why);
 289                 }
 290         } else
 291                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 292         oopscount++;
 293         while (total < kmsg_bytes) {
 294                 char *dst;
 295                 unsigned long size;
 296                 int hsize;
 297                 int zipped_len = -1;
 298                 size_t len;
 299                 bool compressed;
 300                 size_t total_len;
 301
 302                 if (big_oops_buf) {
 303                         dst = big_oops_buf;
 304                         hsize = sprintf(dst, "%s#%d Part%u\n", why,
 305                                                         oopscount, part);
 306                         size = big_oops_buf_sz - hsize;
 307
 308                         if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
 309                                                                 size, &len))
 310                                 break;
 311
 312                         zipped_len = pstore_compress(dst, psinfo->buf,
 313                                                 hsize + len, psinfo->bufsize);
 314
 315                         if (zipped_len > 0) {
 316                                 compressed = true;
 317                                 total_len = zipped_len;
 318                         } else {
 319                                 compressed = false;
 320                                 total_len = copy_kmsg_to_buffer(hsize, len);
 321                         }
 322                 } else {
 323                         dst = psinfo->buf;
 324                         hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount,
 325                                                                         part);
 326                         size = psinfo->bufsize - hsize;
 327                         dst += hsize;
 328
 329                         if (!kmsg_dump_get_buffer(dumper, true, dst,
 330                                                                 size, &len))
 331                                 break;
 332
 333                         compressed = false;
 334                         total_len = hsize + len;
 335                 }
 336
 337                 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
 338                                     oopscount, compressed, total_len, psinfo);
 339                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 340                         pstore_new_entry = 1;
 341
 342                 total += total_len;
 343                 part++;
 344         }
 345         if (pstore_cannot_block_path(reason)) {
 346                 if (is_locked)
 347                         spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 348         } else
 349                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 350 }
 351
 352 static struct kmsg_dumper pstore_dumper = {
 353         .dump = pstore_dump,
 354 };
 355
 356 #ifdef CONFIG_PSTORE_CONSOLE
 357 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 358 {
 359         const char *e = s + c;
 360
 361         while (s < e) {
 362                 unsigned long flags;
 363                 u64 id;
 364
 365                 if (c > psinfo->bufsize)
 366                         c = psinfo->bufsize;
 367
 368                 if (oops_in_progress) {
 369                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 370                                 break;
 371                 } else {
 372                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 373                 }
 374                 memcpy(psinfo->buf, s, c);
 375                 psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
 376                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 377                 s += c;
 378                 c = e - s;
 379         }
 380 }
 381
 382 static struct console pstore_console = {
 383         .name   = "pstore",
 384         .write  = pstore_console_write,
 385         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 386         .index  = -1,
 387 };
 388
 389 static void pstore_register_console(void)
 390 {
 391         register_console(&pstore_console);
 392 }
 393 #else
 394 static void pstore_register_console(void) {}
 395 #endif
 396
 397 static int pstore_write_compat(enum pstore_type_id type,
 398                                enum kmsg_dump_reason reason,
 399                                u64 *id, unsigned int part, int count,
 400                                bool compressed, size_t size,
 401                                struct pstore_info *psi)
 402 {
 403         return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
 404                              size, psi);
 405 }
 406
 407 /*
 408  * platform specific persistent storage driver registers with
 409  * us here. If pstore is already mounted, call the platform
 410  * read function right away to populate the file system. If not
 411  * then the pstore mount code will call us later to fill out
 412  * the file system.
 413  *
 414  * Register with kmsg_dump to save last part of console log on panic.
 415  */
 416 int pstore_register(struct pstore_info *psi)
 417 {
 418         struct module *owner = psi->owner;
 419
 420         if (backend && strcmp(backend, psi->name))
 421                 return -EPERM;
 422
 423         spin_lock(&pstore_lock);
 424         if (psinfo) {
 425                 spin_unlock(&pstore_lock);
 426                 return -EBUSY;
 427         }
 428
 429         if (!psi->write)
 430                 psi->write = pstore_write_compat;
 431         psinfo = psi;
 432         mutex_init(&psinfo->read_mutex);
 433         spin_unlock(&pstore_lock);
 434
 435         if (owner && !try_module_get(owner)) {
 436                 psinfo = NULL;
 437                 return -EINVAL;
 438         }
 439
 440         allocate_buf_for_compression();
 441
 442         if (pstore_is_mounted())
 443                 pstore_get_records(0);
 444
 445         kmsg_dump_register(&pstore_dumper);
 446
 447         if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
 448                 pstore_register_console();
 449                 pstore_register_ftrace();
 450                 pstore_register_pmsg();
 451         }
 452
 453         if (pstore_update_ms >= 0) {
 454                 pstore_timer.expires = jiffies +
 455                         msecs_to_jiffies(pstore_update_ms);
 456                 add_timer(&pstore_timer);
 457         }
 458
 459         pr_info("Registered %s as persistent store backend\n", psi->name);
 460
 461         return 0;
 462 }
 463 EXPORT_SYMBOL_GPL(pstore_register);
 464
 465 /*
 466  * Read all the records from the persistent store. Create
 467  * files in our filesystem.  Don't warn about -EEXIST errors
 468  * when we are re-scanning the backing store looking to add new
 469  * error records.
 470  */
 471 void pstore_get_records(int quiet)
 472 {
 473         struct pstore_info *psi = psinfo;
 474         char                    *buf = NULL;
 475         ssize_t                 size;
 476         u64                     id;
 477         int                     count;
 478         enum pstore_type_id     type;
 479         struct timespec         time;
 480         int                     failed = 0, rc;
 481         bool                    compressed;
 482         int                     unzipped_len = -1;
 483
 484         if (!psi)
 485                 return;
 486
 487         mutex_lock(&psi->read_mutex);
 488         if (psi->open && psi->open(psi))
 489                 goto out;
 490
 491         while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
 492                                 psi)) > 0) {
 493                 if (compressed && (type == PSTORE_TYPE_DMESG)) {
 494                         if (big_oops_buf)
 495                                 unzipped_len = pstore_decompress(buf,
 496                                                         big_oops_buf, size,
 497                                                         big_oops_buf_sz);
 498
 499                         if (unzipped_len > 0) {
 500                                 kfree(buf);
 501                                 buf = big_oops_buf;
 502                                 size = unzipped_len;
 503                                 compressed = false;
 504                         } else {
 505                                 pr_err("decompression failed;returned %d\n",
 506                                        unzipped_len);
 507                                 compressed = true;
 508                         }
 509                 }
 510                 rc = pstore_mkfile(type, psi->name, id, count, buf,
 511                                   compressed, (size_t)size, time, psi);
 512                 if (unzipped_len < 0) {
 513                         /* Free buffer other than big oops */
 514                         kfree(buf);
 515                         buf = NULL;
 516                 } else
 517                         unzipped_len = -1;
 518                 if (rc && (rc != -EEXIST || !quiet))
 519                         failed++;
 520         }
 521         if (psi->close)
 522                 psi->close(psi);
 523 out:
 524         mutex_unlock(&psi->read_mutex);
 525
 526         if (failed)
 527                 pr_warn("failed to load %d record(s) from '%s'\n",
 528                         failed, psi->name);
 529 }
 530
 531 static void pstore_dowork(struct work_struct *work)
 532 {
 533         pstore_get_records(1);
 534 }
 535
 536 static void pstore_timefunc(unsigned long dummy)
 537 {
 538         if (pstore_new_entry) {
 539                 pstore_new_entry = 0;
 540                 schedule_work(&pstore_work);
 541         }
 542
 543         mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 544 }
 545
 546 module_param(backend, charp, 0444);
 547 MODULE_PARM_DESC(backend, "Pstore backend to use");