lib/dynamic_debug.c

   1 /*
   2  * lib/dynamic_debug.c
   3  *
   4  * make pr_debug()/dev_dbg() calls runtime configurable based upon their
   5  * source module.
   6  *
   7  * Copyright (C) 2008 Jason Baron <jbaron@redhat.com>
   8  * By Greg Banks <gnb@melbourne.sgi.com>
   9  * Copyright (c) 2008 Silicon Graphics Inc.  All Rights Reserved.
  10  * Copyright (C) 2011 Bart Van Assche.  All Rights Reserved.
  11  * Copyright (C) 2013 Du, Changbin <changbin.du@gmail.com>
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/kallsyms.h>
  20 #include <linux/types.h>
  21 #include <linux/mutex.h>
  22 #include <linux/proc_fs.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/list.h>
  25 #include <linux/sysctl.h>
  26 #include <linux/ctype.h>
  27 #include <linux/string.h>
  28 #include <linux/parser.h>
  29 #include <linux/string_helpers.h>
  30 #include <linux/uaccess.h>
  31 #include <linux/dynamic_debug.h>
  32 #include <linux/debugfs.h>
  33 #include <linux/slab.h>
  34 #include <linux/jump_label.h>
  35 #include <linux/hardirq.h>
  36 #include <linux/sched.h>
  37 #include <linux/device.h>
  38 #include <linux/netdevice.h>
  39
  40 extern struct _ddebug __start___verbose[];
  41 extern struct _ddebug __stop___verbose[];
  42
  43 struct ddebug_table {
  44         struct list_head link;
  45         const char *mod_name;
  46         unsigned int num_ddebugs;
  47         struct _ddebug *ddebugs;
  48 };
  49
  50 struct ddebug_query {
  51         const char *filename;
  52         const char *module;
  53         const char *function;
  54         const char *format;
  55         unsigned int first_lineno, last_lineno;
  56 };
  57
  58 struct ddebug_iter {
  59         struct ddebug_table *table;
  60         unsigned int idx;
  61 };
  62
  63 static DEFINE_MUTEX(ddebug_lock);
  64 static LIST_HEAD(ddebug_tables);
  65 static int verbose;
  66 module_param(verbose, int, 0644);
  67
  68 /* Return the path relative to source root */
  69 static inline const char *trim_prefix(const char *path)
  70 {
  71         int skip = strlen(__FILE__) - strlen("lib/dynamic_debug.c");
  72
  73         if (strncmp(path, __FILE__, skip))
  74                 skip = 0; /* prefix mismatch, don't skip */
  75
  76         return path + skip;
  77 }
  78
  79 static struct { unsigned flag:8; char opt_char; } opt_array[] = {
  80         { _DPRINTK_FLAGS_PRINT, 'p' },
  81         { _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
  82         { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
  83         { _DPRINTK_FLAGS_INCL_LINENO, 'l' },
  84         { _DPRINTK_FLAGS_INCL_TID, 't' },
  85         { _DPRINTK_FLAGS_NONE, '_' },
  86 };
  87
  88 /* format a string into buf[] which describes the _ddebug's flags */
  89 static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
  90                                     size_t maxlen)
  91 {
  92         char *p = buf;
  93         int i;
  94
  95         BUG_ON(maxlen < 6);
  96         for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
  97                 if (dp->flags & opt_array[i].flag)
  98                         *p++ = opt_array[i].opt_char;
  99         if (p == buf)
 100                 *p++ = '_';
 101         *p = '\0';
 102
 103         return buf;
 104 }
 105
 106 #define vpr_info(fmt, ...)                                      \
 107 do {                                                            \
 108         if (verbose)                                            \
 109                 pr_info(fmt, ##__VA_ARGS__);                    \
 110 } while (0)
 111
 112 static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
 113 {
 114         /* trim any trailing newlines */
 115         int fmtlen = 0;
 116
 117         if (query->format) {
 118                 fmtlen = strlen(query->format);
 119                 while (fmtlen && query->format[fmtlen - 1] == '\n')
 120                         fmtlen--;
 121         }
 122
 123         vpr_info("%s: func=\"%s\" file=\"%s\" module=\"%s\" format=\"%.*s\" lineno=%u-%u\n",
 124                  msg,
 125                  query->function ? query->function : "",
 126                  query->filename ? query->filename : "",
 127                  query->module ? query->module : "",
 128                  fmtlen, query->format ? query->format : "",
 129                  query->first_lineno, query->last_lineno);
 130 }
 131
 132 /*
 133  * Search the tables for _ddebug's which match the given `query' and
 134  * apply the `flags' and `mask' to them.  Returns number of matching
 135  * callsites, normally the same as number of changes.  If verbose,
 136  * logs the changes.  Takes ddebug_lock.
 137  */
 138 static int ddebug_change(const struct ddebug_query *query,
 139                         unsigned int flags, unsigned int mask)
 140 {
 141         int i;
 142         struct ddebug_table *dt;
 143         unsigned int newflags;
 144         unsigned int nfound = 0;
 145         char flagbuf[10];
 146
 147         /* search for matching ddebugs */
 148         mutex_lock(&ddebug_lock);
 149         list_for_each_entry(dt, &ddebug_tables, link) {
 150
 151                 /* match against the module name */
 152                 if (query->module &&
 153                     !match_wildcard(query->module, dt->mod_name))
 154                         continue;
 155
 156                 for (i = 0; i < dt->num_ddebugs; i++) {
 157                         struct _ddebug *dp = &dt->ddebugs[i];
 158
 159                         /* match against the source filename */
 160                         if (query->filename &&
 161                             !match_wildcard(query->filename, dp->filename) &&
 162                             !match_wildcard(query->filename,
 163                                            kbasename(dp->filename)) &&
 164                             !match_wildcard(query->filename,
 165                                            trim_prefix(dp->filename)))
 166                                 continue;
 167
 168                         /* match against the function */
 169                         if (query->function &&
 170                             !match_wildcard(query->function, dp->function))
 171                                 continue;
 172
 173                         /* match against the format */
 174                         if (query->format &&
 175                             !strstr(dp->format, query->format))
 176                                 continue;
 177
 178                         /* match against the line number range */
 179                         if (query->first_lineno &&
 180                             dp->lineno < query->first_lineno)
 181                                 continue;
 182                         if (query->last_lineno &&
 183                             dp->lineno > query->last_lineno)
 184                                 continue;
 185
 186                         nfound++;
 187
 188                         newflags = (dp->flags & mask) | flags;
 189                         if (newflags == dp->flags)
 190                                 continue;
 191                         dp->flags = newflags;
 192                         vpr_info("changed %s:%d [%s]%s =%s\n",
 193                                  trim_prefix(dp->filename), dp->lineno,
 194                                  dt->mod_name, dp->function,
 195                                  ddebug_describe_flags(dp, flagbuf,
 196                                                        sizeof(flagbuf)));
 197                 }
 198         }
 199         mutex_unlock(&ddebug_lock);
 200
 201         if (!nfound && verbose)
 202                 pr_info("no matches for query\n");
 203
 204         return nfound;
 205 }
 206
 207 /*
 208  * Split the buffer `buf' into space-separated words.
 209  * Handles simple " and ' quoting, i.e. without nested,
 210  * embedded or escaped \".  Return the number of words
 211  * or <0 on error.
 212  */
 213 static int ddebug_tokenize(char *buf, char *words[], int maxwords)
 214 {
 215         int nwords = 0;
 216
 217         while (*buf) {
 218                 char *end;
 219
 220                 /* Skip leading whitespace */
 221                 buf = skip_spaces(buf);
 222                 if (!*buf)
 223                         break;  /* oh, it was trailing whitespace */
 224                 if (*buf == '#')
 225                         break;  /* token starts comment, skip rest of line */
 226
 227                 /* find `end' of word, whitespace separated or quoted */
 228                 if (*buf == '"' || *buf == '\'') {
 229                         int quote = *buf++;
 230                         for (end = buf; *end && *end != quote; end++)
 231                                 ;
 232                         if (!*end) {
 233                                 pr_err("unclosed quote: %s\n", buf);
 234                                 return -EINVAL; /* unclosed quote */
 235                         }
 236                 } else {
 237                         for (end = buf; *end && !isspace(*end); end++)
 238                                 ;
 239                         BUG_ON(end == buf);
 240                 }
 241
 242                 /* `buf' is start of word, `end' is one past its end */
 243                 if (nwords == maxwords) {
 244                         pr_err("too many words, legal max <=%d\n", maxwords);
 245                         return -EINVAL; /* ran out of words[] before bytes */
 246                 }
 247                 if (*end)
 248                         *end++ = '\0';  /* terminate the word */
 249                 words[nwords++] = buf;
 250                 buf = end;
 251         }
 252
 253         if (verbose) {
 254                 int i;
 255                 pr_info("split into words:");
 256                 for (i = 0; i < nwords; i++)
 257                         pr_cont(" \"%s\"", words[i]);
 258                 pr_cont("\n");
 259         }
 260
 261         return nwords;
 262 }
 263
 264 /*
 265  * Parse a single line number.  Note that the empty string ""
 266  * is treated as a special case and converted to zero, which
 267  * is later treated as a "don't care" value.
 268  */
 269 static inline int parse_lineno(const char *str, unsigned int *val)
 270 {
 271         BUG_ON(str == NULL);
 272         if (*str == '\0') {
 273                 *val = 0;
 274                 return 0;
 275         }
 276         if (kstrtouint(str, 10, val) < 0) {
 277                 pr_err("bad line-number: %s\n", str);
 278                 return -EINVAL;
 279         }
 280         return 0;
 281 }
 282
 283 static int check_set(const char **dest, char *src, char *name)
 284 {
 285         int rc = 0;
 286
 287         if (*dest) {
 288                 rc = -EINVAL;
 289                 pr_err("match-spec:%s val:%s overridden by %s\n",
 290                        name, *dest, src);
 291         }
 292         *dest = src;
 293         return rc;
 294 }
 295
 296 /*
 297  * Parse words[] as a ddebug query specification, which is a series
 298  * of (keyword, value) pairs chosen from these possibilities:
 299  *
 300  * func <function-name>
 301  * file <full-pathname>
 302  * file <base-filename>
 303  * module <module-name>
 304  * format <escaped-string-to-find-in-format>
 305  * line <lineno>
 306  * line <first-lineno>-<last-lineno> // where either may be empty
 307  *
 308  * Only 1 of each type is allowed.
 309  * Returns 0 on success, <0 on error.
 310  */
 311 static int ddebug_parse_query(char *words[], int nwords,
 312                         struct ddebug_query *query, const char *modname)
 313 {
 314         unsigned int i;
 315         int rc = 0;
 316
 317         /* check we have an even number of words */
 318         if (nwords % 2 != 0) {
 319                 pr_err("expecting pairs of match-spec <value>\n");
 320                 return -EINVAL;
 321         }
 322         memset(query, 0, sizeof(*query));
 323
 324         if (modname)
 325                 /* support $modname.dyndbg=<multiple queries> */
 326                 query->module = modname;
 327
 328         for (i = 0; i < nwords; i += 2) {
 329                 if (!strcmp(words[i], "func")) {
 330                         rc = check_set(&query->function, words[i+1], "func");
 331                 } else if (!strcmp(words[i], "file")) {
 332                         rc = check_set(&query->filename, words[i+1], "file");
 333                 } else if (!strcmp(words[i], "module")) {
 334                         rc = check_set(&query->module, words[i+1], "module");
 335                 } else if (!strcmp(words[i], "format")) {
 336                         string_unescape_inplace(words[i+1], UNESCAPE_SPACE |
 337                                                             UNESCAPE_OCTAL |
 338                                                             UNESCAPE_SPECIAL);
 339                         rc = check_set(&query->format, words[i+1], "format");
 340                 } else if (!strcmp(words[i], "line")) {
 341                         char *first = words[i+1];
 342                         char *last = strchr(first, '-');
 343                         if (query->first_lineno || query->last_lineno) {
 344                                 pr_err("match-spec: line used 2x\n");
 345                                 return -EINVAL;
 346                         }
 347                         if (last)
 348                                 *last++ = '\0';
 349                         if (parse_lineno(first, &query->first_lineno) < 0)
 350                                 return -EINVAL;
 351                         if (last) {
 352                                 /* range <first>-<last> */
 353                                 if (parse_lineno(last, &query->last_lineno) < 0)
 354                                         return -EINVAL;
 355
 356                                 if (query->last_lineno < query->first_lineno) {
 357                                         pr_err("last-line:%d < 1st-line:%d\n",
 358                                                 query->last_lineno,
 359                                                 query->first_lineno);
 360                                         return -EINVAL;
 361                                 }
 362                         } else {
 363                                 query->last_lineno = query->first_lineno;
 364                         }
 365                 } else {
 366                         pr_err("unknown keyword \"%s\"\n", words[i]);
 367                         return -EINVAL;
 368                 }
 369                 if (rc)
 370                         return rc;
 371         }
 372         vpr_info_dq(query, "parsed");
 373         return 0;
 374 }
 375
 376 /*
 377  * Parse `str' as a flags specification, format [-+=][p]+.
 378  * Sets up *maskp and *flagsp to be used when changing the
 379  * flags fields of matched _ddebug's.  Returns 0 on success
 380  * or <0 on error.
 381  */
 382 static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 383                                unsigned int *maskp)
 384 {
 385         unsigned flags = 0;
 386         int op = '=', i;
 387
 388         switch (*str) {
 389         case '+':
 390         case '-':
 391         case '=':
 392                 op = *str++;
 393                 break;
 394         default:
 395                 pr_err("bad flag-op %c, at start of %s\n", *str, str);
 396                 return -EINVAL;
 397         }
 398         vpr_info("op='%c'\n", op);
 399
 400         for (; *str ; ++str) {
 401                 for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
 402                         if (*str == opt_array[i].opt_char) {
 403                                 flags |= opt_array[i].flag;
 404                                 break;
 405                         }
 406                 }
 407                 if (i < 0) {
 408                         pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
 409                         return -EINVAL;
 410                 }
 411         }
 412         vpr_info("flags=0x%x\n", flags);
 413
 414         /* calculate final *flagsp, *maskp according to mask and op */
 415         switch (op) {
 416         case '=':
 417                 *maskp = 0;
 418                 *flagsp = flags;
 419                 break;
 420         case '+':
 421                 *maskp = ~0U;
 422                 *flagsp = flags;
 423                 break;
 424         case '-':
 425                 *maskp = ~flags;
 426                 *flagsp = 0;
 427                 break;
 428         }
 429         vpr_info("*flagsp=0x%x *maskp=0x%x\n", *flagsp, *maskp);
 430         return 0;
 431 }
 432
 433 static int ddebug_exec_query(char *query_string, const char *modname)
 434 {
 435         unsigned int flags = 0, mask = 0;
 436         struct ddebug_query query;
 437 #define MAXWORDS 9
 438         int nwords, nfound;
 439         char *words[MAXWORDS];
 440
 441         nwords = ddebug_tokenize(query_string, words, MAXWORDS);
 442         if (nwords <= 0) {
 443                 pr_err("tokenize failed\n");
 444                 return -EINVAL;
 445         }
 446         /* check flags 1st (last arg) so query is pairs of spec,val */
 447         if (ddebug_parse_flags(words[nwords-1], &flags, &mask)) {
 448                 pr_err("flags parse failed\n");
 449                 return -EINVAL;
 450         }
 451         if (ddebug_parse_query(words, nwords-1, &query, modname)) {
 452                 pr_err("query parse failed\n");
 453                 return -EINVAL;
 454         }
 455         /* actually go and implement the change */
 456         nfound = ddebug_change(&query, flags, mask);
 457         vpr_info_dq(&query, nfound ? "applied" : "no-match");
 458
 459         return nfound;
 460 }
 461
 462 /* handle multiple queries in query string, continue on error, return
 463    last error or number of matching callsites.  Module name is either
 464    in param (for boot arg) or perhaps in query string.
 465 */
 466 static int ddebug_exec_queries(char *query, const char *modname)
 467 {
 468         char *split;
 469         int i, errs = 0, exitcode = 0, rc, nfound = 0;
 470
 471         for (i = 0; query; query = split) {
 472                 split = strpbrk(query, ";\n");
 473                 if (split)
 474                         *split++ = '\0';
 475
 476                 query = skip_spaces(query);
 477                 if (!query || !*query || *query == '#')
 478                         continue;
 479
 480                 vpr_info("query %d: \"%s\"\n", i, query);
 481
 482                 rc = ddebug_exec_query(query, modname);
 483                 if (rc < 0) {
 484                         errs++;
 485                         exitcode = rc;
 486                 } else {
 487                         nfound += rc;
 488                 }
 489                 i++;
 490         }
 491         vpr_info("processed %d queries, with %d matches, %d errs\n",
 492                  i, nfound, errs);
 493
 494         if (exitcode)
 495                 return exitcode;
 496         return nfound;
 497 }
 498
 499 #define PREFIX_SIZE 64
 500
 501 static int remaining(int wrote)
 502 {
 503         if (PREFIX_SIZE - wrote > 0)
 504                 return PREFIX_SIZE - wrote;
 505         return 0;
 506 }
 507
 508 static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
 509 {
 510         int pos_after_tid;
 511         int pos = 0;
 512
 513         *buf = '\0';
 514
 515         if (desc->flags & _DPRINTK_FLAGS_INCL_TID) {
 516                 if (in_interrupt())
 517                         pos += snprintf(buf + pos, remaining(pos), "<intr> ");
 518                 else
 519                         pos += snprintf(buf + pos, remaining(pos), "[%d] ",
 520                                         task_pid_vnr(current));
 521         }
 522         pos_after_tid = pos;
 523         if (desc->flags & _DPRINTK_FLAGS_INCL_MODNAME)
 524                 pos += snprintf(buf + pos, remaining(pos), "%s:",
 525                                 desc->modname);
 526         if (desc->flags & _DPRINTK_FLAGS_INCL_FUNCNAME)
 527                 pos += snprintf(buf + pos, remaining(pos), "%s:",
 528                                 desc->function);
 529         if (desc->flags & _DPRINTK_FLAGS_INCL_LINENO)
 530                 pos += snprintf(buf + pos, remaining(pos), "%d:",
 531                                 desc->lineno);
 532         if (pos - pos_after_tid)
 533                 pos += snprintf(buf + pos, remaining(pos), " ");
 534         if (pos >= PREFIX_SIZE)
 535                 buf[PREFIX_SIZE - 1] = '\0';
 536
 537         return buf;
 538 }
 539
 540 void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...)
 541 {
 542         va_list args;
 543         struct va_format vaf;
 544         char buf[PREFIX_SIZE];
 545
 546         BUG_ON(!descriptor);
 547         BUG_ON(!fmt);
 548
 549         va_start(args, fmt);
 550
 551         vaf.fmt = fmt;
 552         vaf.va = &args;
 553
 554         printk(KERN_DEBUG "%s%pV", dynamic_emit_prefix(descriptor, buf), &vaf);
 555
 556         va_end(args);
 557 }
 558 EXPORT_SYMBOL(__dynamic_pr_debug);
 559
 560 void __dynamic_dev_dbg(struct _ddebug *descriptor,
 561                       const struct device *dev, const char *fmt, ...)
 562 {
 563         struct va_format vaf;
 564         va_list args;
 565
 566         BUG_ON(!descriptor);
 567         BUG_ON(!fmt);
 568
 569         va_start(args, fmt);
 570
 571         vaf.fmt = fmt;
 572         vaf.va = &args;
 573
 574         if (!dev) {
 575                 printk(KERN_DEBUG "(NULL device *): %pV", &vaf);
 576         } else {
 577                 char buf[PREFIX_SIZE];
 578
 579                 dev_printk_emit(LOGLEVEL_DEBUG, dev, "%s%s %s: %pV",
 580                                 dynamic_emit_prefix(descriptor, buf),
 581                                 dev_driver_string(dev), dev_name(dev),
 582                                 &vaf);
 583         }
 584
 585         va_end(args);
 586 }
 587 EXPORT_SYMBOL(__dynamic_dev_dbg);
 588
 589 #ifdef CONFIG_NET
 590
 591 void __dynamic_netdev_dbg(struct _ddebug *descriptor,
 592                           const struct net_device *dev, const char *fmt, ...)
 593 {
 594         struct va_format vaf;
 595         va_list args;
 596
 597         BUG_ON(!descriptor);
 598         BUG_ON(!fmt);
 599
 600         va_start(args, fmt);
 601
 602         vaf.fmt = fmt;
 603         vaf.va = &args;
 604
 605         if (dev && dev->dev.parent) {
 606                 char buf[PREFIX_SIZE];
 607
 608                 dev_printk_emit(LOGLEVEL_DEBUG, dev->dev.parent,
 609                                 "%s%s %s %s%s: %pV",
 610                                 dynamic_emit_prefix(descriptor, buf),
 611                                 dev_driver_string(dev->dev.parent),
 612                                 dev_name(dev->dev.parent),
 613                                 netdev_name(dev), netdev_reg_state(dev),
 614                                 &vaf);
 615         } else if (dev) {
 616                 printk(KERN_DEBUG "%s%s: %pV", netdev_name(dev),
 617                        netdev_reg_state(dev), &vaf);
 618         } else {
 619                 printk(KERN_DEBUG "(NULL net_device): %pV", &vaf);
 620         }
 621
 622         va_end(args);
 623 }
 624 EXPORT_SYMBOL(__dynamic_netdev_dbg);
 625
 626 #endif
 627
 628 #define DDEBUG_STRING_SIZE 1024
 629 static __initdata char ddebug_setup_string[DDEBUG_STRING_SIZE];
 630
 631 static __init int ddebug_setup_query(char *str)
 632 {
 633         if (strlen(str) >= DDEBUG_STRING_SIZE) {
 634                 pr_warn("ddebug boot param string too large\n");
 635                 return 0;
 636         }
 637         strlcpy(ddebug_setup_string, str, DDEBUG_STRING_SIZE);
 638         return 1;
 639 }
 640
 641 __setup("ddebug_query=", ddebug_setup_query);
 642
 643 /*
 644  * File_ops->write method for <debugfs>/dynamic_debug/control.  Gathers the
 645  * command text from userspace, parses and executes it.
 646  */
 647 #define USER_BUF_PAGE 4096
 648 static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
 649                                   size_t len, loff_t *offp)
 650 {
 651         char *tmpbuf;
 652         int ret;
 653
 654         if (len == 0)
 655                 return 0;
 656         if (len > USER_BUF_PAGE - 1) {
 657                 pr_warn("expected <%d bytes into control\n", USER_BUF_PAGE);
 658                 return -E2BIG;
 659         }
 660         tmpbuf = memdup_user_nul(ubuf, len);
 661         if (IS_ERR(tmpbuf))
 662                 return PTR_ERR(tmpbuf);
 663         vpr_info("read %d bytes from userspace\n", (int)len);
 664
 665         ret = ddebug_exec_queries(tmpbuf, NULL);
 666         kfree(tmpbuf);
 667         if (ret < 0)
 668                 return ret;
 669
 670         *offp += len;
 671         return len;
 672 }
 673
 674 /*
 675  * Set the iterator to point to the first _ddebug object
 676  * and return a pointer to that first object.  Returns
 677  * NULL if there are no _ddebugs at all.
 678  */
 679 static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
 680 {
 681         if (list_empty(&ddebug_tables)) {
 682                 iter->table = NULL;
 683                 iter->idx = 0;
 684                 return NULL;
 685         }
 686         iter->table = list_entry(ddebug_tables.next,
 687                                  struct ddebug_table, link);
 688         iter->idx = 0;
 689         return &iter->table->ddebugs[iter->idx];
 690 }
 691
 692 /*
 693  * Advance the iterator to point to the next _ddebug
 694  * object from the one the iterator currently points at,
 695  * and returns a pointer to the new _ddebug.  Returns
 696  * NULL if the iterator has seen all the _ddebugs.
 697  */
 698 static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
 699 {
 700         if (iter->table == NULL)
 701                 return NULL;
 702         if (++iter->idx == iter->table->num_ddebugs) {
 703                 /* iterate to next table */
 704                 iter->idx = 0;
 705                 if (list_is_last(&iter->table->link, &ddebug_tables)) {
 706                         iter->table = NULL;
 707                         return NULL;
 708                 }
 709                 iter->table = list_entry(iter->table->link.next,
 710                                          struct ddebug_table, link);
 711         }
 712         return &iter->table->ddebugs[iter->idx];
 713 }
 714
 715 /*
 716  * Seq_ops start method.  Called at the start of every
 717  * read() call from userspace.  Takes the ddebug_lock and
 718  * seeks the seq_file's iterator to the given position.
 719  */
 720 static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
 721 {
 722         struct ddebug_iter *iter = m->private;
 723         struct _ddebug *dp;
 724         int n = *pos;
 725
 726         vpr_info("called m=%p *pos=%lld\n", m, (unsigned long long)*pos);
 727
 728         mutex_lock(&ddebug_lock);
 729
 730         if (!n)
 731                 return SEQ_START_TOKEN;
 732         if (n < 0)
 733                 return NULL;
 734         dp = ddebug_iter_first(iter);
 735         while (dp != NULL && --n > 0)
 736                 dp = ddebug_iter_next(iter);
 737         return dp;
 738 }
 739
 740 /*
 741  * Seq_ops next method.  Called several times within a read()
 742  * call from userspace, with ddebug_lock held.  Walks to the
 743  * next _ddebug object with a special case for the header line.
 744  */
 745 static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
 746 {
 747         struct ddebug_iter *iter = m->private;
 748         struct _ddebug *dp;
 749
 750         vpr_info("called m=%p p=%p *pos=%lld\n",
 751                  m, p, (unsigned long long)*pos);
 752
 753         if (p == SEQ_START_TOKEN)
 754                 dp = ddebug_iter_first(iter);
 755         else
 756                 dp = ddebug_iter_next(iter);
 757         ++*pos;
 758         return dp;
 759 }
 760
 761 /*
 762  * Seq_ops show method.  Called several times within a read()
 763  * call from userspace, with ddebug_lock held.  Formats the
 764  * current _ddebug as a single human-readable line, with a
 765  * special case for the header line.
 766  */
 767 static int ddebug_proc_show(struct seq_file *m, void *p)
 768 {
 769         struct ddebug_iter *iter = m->private;
 770         struct _ddebug *dp = p;
 771         char flagsbuf[10];
 772
 773         vpr_info("called m=%p p=%p\n", m, p);
 774
 775         if (p == SEQ_START_TOKEN) {
 776                 seq_puts(m,
 777                          "# filename:lineno [module]function flags format\n");
 778                 return 0;
 779         }
 780
 781         seq_printf(m, "%s:%u [%s]%s =%s \"",
 782                    trim_prefix(dp->filename), dp->lineno,
 783                    iter->table->mod_name, dp->function,
 784                    ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
 785         seq_escape(m, dp->format, "\t\r\n\"");
 786         seq_puts(m, "\"\n");
 787
 788         return 0;
 789 }
 790
 791 /*
 792  * Seq_ops stop method.  Called at the end of each read()
 793  * call from userspace.  Drops ddebug_lock.
 794  */
 795 static void ddebug_proc_stop(struct seq_file *m, void *p)
 796 {
 797         vpr_info("called m=%p p=%p\n", m, p);
 798         mutex_unlock(&ddebug_lock);
 799 }
 800
 801 static const struct seq_operations ddebug_proc_seqops = {
 802         .start = ddebug_proc_start,
 803         .next = ddebug_proc_next,
 804         .show = ddebug_proc_show,
 805         .stop = ddebug_proc_stop
 806 };
 807
 808 /*
 809  * File_ops->open method for <debugfs>/dynamic_debug/control.  Does
 810  * the seq_file setup dance, and also creates an iterator to walk the
 811  * _ddebugs.  Note that we create a seq_file always, even for O_WRONLY
 812  * files where it's not needed, as doing so simplifies the ->release
 813  * method.
 814  */
 815 static int ddebug_proc_open(struct inode *inode, struct file *file)
 816 {
 817         vpr_info("called\n");
 818         return seq_open_private(file, &ddebug_proc_seqops,
 819                                 sizeof(struct ddebug_iter));
 820 }
 821
 822 static const struct file_operations ddebug_proc_fops = {
 823         .owner = THIS_MODULE,
 824         .open = ddebug_proc_open,
 825         .read = seq_read,
 826         .llseek = seq_lseek,
 827         .release = seq_release_private,
 828         .write = ddebug_proc_write
 829 };
 830
 831 /*
 832  * Allocate a new ddebug_table for the given module
 833  * and add it to the global list.
 834  */
 835 int ddebug_add_module(struct _ddebug *tab, unsigned int n,
 836                              const char *name)
 837 {
 838         struct ddebug_table *dt;
 839         const char *new_name;
 840
 841         dt = kzalloc(sizeof(*dt), GFP_KERNEL);
 842         if (dt == NULL)
 843                 return -ENOMEM;
 844         new_name = kstrdup_const(name, GFP_KERNEL);
 845         if (new_name == NULL) {
 846                 kfree(dt);
 847                 return -ENOMEM;
 848         }
 849         dt->mod_name = new_name;
 850         dt->num_ddebugs = n;
 851         dt->ddebugs = tab;
 852
 853         mutex_lock(&ddebug_lock);
 854         list_add_tail(&dt->link, &ddebug_tables);
 855         mutex_unlock(&ddebug_lock);
 856
 857         vpr_info("%u debug prints in module %s\n", n, dt->mod_name);
 858         return 0;
 859 }
 860 EXPORT_SYMBOL_GPL(ddebug_add_module);
 861
 862 /* helper for ddebug_dyndbg_(boot|module)_param_cb */
 863 static int ddebug_dyndbg_param_cb(char *param, char *val,
 864                                 const char *modname, int on_err)
 865 {
 866         char *sep;
 867
 868         sep = strchr(param, '.');
 869         if (sep) {
 870                 /* needed only for ddebug_dyndbg_boot_param_cb */
 871                 *sep = '\0';
 872                 modname = param;
 873                 param = sep + 1;
 874         }
 875         if (strcmp(param, "dyndbg"))
 876                 return on_err; /* determined by caller */
 877
 878         ddebug_exec_queries((val ? val : "+p"), modname);
 879
 880         return 0; /* query failure shouldnt stop module load */
 881 }
 882
 883 /* handle both dyndbg and $module.dyndbg params at boot */
 884 static int ddebug_dyndbg_boot_param_cb(char *param, char *val,
 885                                 const char *unused, void *arg)
 886 {
 887         vpr_info("%s=\"%s\"\n", param, val);
 888         return ddebug_dyndbg_param_cb(param, val, NULL, 0);
 889 }
 890
 891 /*
 892  * modprobe foo finds foo.params in boot-args, strips "foo.", and
 893  * passes them to load_module().  This callback gets unknown params,
 894  * processes dyndbg params, rejects others.
 895  */
 896 int ddebug_dyndbg_module_param_cb(char *param, char *val, const char *module)
 897 {
 898         vpr_info("module: %s %s=\"%s\"\n", module, param, val);
 899         return ddebug_dyndbg_param_cb(param, val, module, -ENOENT);
 900 }
 901
 902 static void ddebug_table_free(struct ddebug_table *dt)
 903 {
 904         list_del_init(&dt->link);
 905         kfree_const(dt->mod_name);
 906         kfree(dt);
 907 }
 908
 909 /*
 910  * Called in response to a module being unloaded.  Removes
 911  * any ddebug_table's which point at the module.
 912  */
 913 int ddebug_remove_module(const char *mod_name)
 914 {
 915         struct ddebug_table *dt, *nextdt;
 916         int ret = -ENOENT;
 917
 918         vpr_info("removing module \"%s\"\n", mod_name);
 919
 920         mutex_lock(&ddebug_lock);
 921         list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
 922                 if (!strcmp(dt->mod_name, mod_name)) {
 923                         ddebug_table_free(dt);
 924                         ret = 0;
 925                 }
 926         }
 927         mutex_unlock(&ddebug_lock);
 928         return ret;
 929 }
 930 EXPORT_SYMBOL_GPL(ddebug_remove_module);
 931
 932 static void ddebug_remove_all_tables(void)
 933 {
 934         mutex_lock(&ddebug_lock);
 935         while (!list_empty(&ddebug_tables)) {
 936                 struct ddebug_table *dt = list_entry(ddebug_tables.next,
 937                                                       struct ddebug_table,
 938                                                       link);
 939                 ddebug_table_free(dt);
 940         }
 941         mutex_unlock(&ddebug_lock);
 942 }
 943
 944 static __initdata int ddebug_init_success;
 945
 946 static int __init dynamic_debug_init_debugfs(void)
 947 {
 948         struct dentry *dir, *file;
 949
 950         if (!ddebug_init_success)
 951                 return -ENODEV;
 952
 953         dir = debugfs_create_dir("dynamic_debug", NULL);
 954         if (!dir)
 955                 return -ENOMEM;
 956         file = debugfs_create_file("control", 0644, dir, NULL,
 957                                         &ddebug_proc_fops);
 958         if (!file) {
 959                 debugfs_remove(dir);
 960                 return -ENOMEM;
 961         }
 962         return 0;
 963 }
 964
 965 static int __init dynamic_debug_init(void)
 966 {
 967         struct _ddebug *iter, *iter_start;
 968         const char *modname = NULL;
 969         char *cmdline;
 970         int ret = 0;
 971         int n = 0, entries = 0, modct = 0;
 972         int verbose_bytes = 0;
 973
 974         if (__start___verbose == __stop___verbose) {
 975                 pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
 976                 return 1;
 977         }
 978         iter = __start___verbose;
 979         modname = iter->modname;
 980         iter_start = iter;
 981         for (; iter < __stop___verbose; iter++) {
 982                 entries++;
 983                 verbose_bytes += strlen(iter->modname) + strlen(iter->function)
 984                         + strlen(iter->filename) + strlen(iter->format);
 985
 986                 if (strcmp(modname, iter->modname)) {
 987                         modct++;
 988                         ret = ddebug_add_module(iter_start, n, modname);
 989                         if (ret)
 990                                 goto out_err;
 991                         n = 0;
 992                         modname = iter->modname;
 993                         iter_start = iter;
 994                 }
 995                 n++;
 996         }
 997         ret = ddebug_add_module(iter_start, n, modname);
 998         if (ret)
 999                 goto out_err;
1000
1001         ddebug_init_success = 1;
1002         vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in (readonly) verbose section\n",
1003                  modct, entries, (int)(modct * sizeof(struct ddebug_table)),
1004                  verbose_bytes + (int)(__stop___verbose - __start___verbose));
1005
1006         /* apply ddebug_query boot param, dont unload tables on err */
1007         if (ddebug_setup_string[0] != '\0') {
1008                 pr_warn("ddebug_query param name is deprecated, change it to dyndbg\n");
1009                 ret = ddebug_exec_queries(ddebug_setup_string, NULL);
1010                 if (ret < 0)
1011                         pr_warn("Invalid ddebug boot param %s\n",
1012                                 ddebug_setup_string);
1013                 else
1014                         pr_info("%d changes by ddebug_query\n", ret);
1015         }
1016         /* now that ddebug tables are loaded, process all boot args
1017          * again to find and activate queries given in dyndbg params.
1018          * While this has already been done for known boot params, it
1019          * ignored the unknown ones (dyndbg in particular).  Reusing
1020          * parse_args avoids ad-hoc parsing.  This will also attempt
1021          * to activate queries for not-yet-loaded modules, which is
1022          * slightly noisy if verbose, but harmless.
1023          */
1024         cmdline = kstrdup(saved_command_line, GFP_KERNEL);
1025         parse_args("dyndbg params", cmdline, NULL,
1026                    0, 0, 0, NULL, &ddebug_dyndbg_boot_param_cb);
1027         kfree(cmdline);
1028         return 0;
1029
1030 out_err:
1031         ddebug_remove_all_tables();
1032         return 0;
1033 }
1034 /* Allow early initialization for boot messages via boot param */
1035 early_initcall(dynamic_debug_init);
1036
1037 /* Debugfs setup must be done later */
1038 fs_initcall(dynamic_debug_init_debugfs);