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  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
  14
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/kallsyms.h>
  19 #include <linux/types.h>
  20 #include <linux/mutex.h>
  21 #include <linux/proc_fs.h>
  22 #include <linux/seq_file.h>
  23 #include <linux/list.h>
  24 #include <linux/sysctl.h>
  25 #include <linux/ctype.h>
  26 #include <linux/string.h>
  27 #include <linux/string_helpers.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/dynamic_debug.h>
  30 #include <linux/debugfs.h>
  31 #include <linux/slab.h>
  32 #include <linux/jump_label.h>
  33 #include <linux/hardirq.h>
  34 #include <linux/sched.h>
  35 #include <linux/device.h>
  36 #include <linux/netdevice.h>
  37
  38 extern struct _ddebug __start___verbose[];
  39 extern struct _ddebug __stop___verbose[];
  40
  41 struct ddebug_table {
  42         struct list_head link;
  43         char *mod_name;
  44         unsigned int num_ddebugs;
  45         struct _ddebug *ddebugs;
  46 };
  47
  48 struct ddebug_query {
  49         const char *filename;
  50         const char *module;
  51         const char *function;
  52         const char *format;
  53         unsigned int first_lineno, last_lineno;
  54 };
  55
  56 struct ddebug_iter {
  57         struct ddebug_table *table;
  58         unsigned int idx;
  59 };
  60
  61 static DEFINE_MUTEX(ddebug_lock);
  62 static LIST_HEAD(ddebug_tables);
  63 static int verbose;
  64 module_param(verbose, int, 0644);
  65
  66 /* Return the path relative to source root */
  67 static inline const char *trim_prefix(const char *path)
  68 {
  69         int skip = strlen(__FILE__) - strlen("lib/dynamic_debug.c");
  70
  71         if (strncmp(path, __FILE__, skip))
  72                 skip = 0; /* prefix mismatch, don't skip */
  73
  74         return path + skip;
  75 }
  76
  77 static struct { unsigned flag:8; char opt_char; } opt_array[] = {
  78         { _DPRINTK_FLAGS_PRINT, 'p' },
  79         { _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
  80         { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
  81         { _DPRINTK_FLAGS_INCL_LINENO, 'l' },
  82         { _DPRINTK_FLAGS_INCL_TID, 't' },
  83         { _DPRINTK_FLAGS_NONE, '_' },
  84 };
  85
  86 /* format a string into buf[] which describes the _ddebug's flags */
  87 static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
  88                                     size_t maxlen)
  89 {
  90         char *p = buf;
  91         int i;
  92
  93         BUG_ON(maxlen < 6);
  94         for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
  95                 if (dp->flags & opt_array[i].flag)
  96                         *p++ = opt_array[i].opt_char;
  97         if (p == buf)
  98                 *p++ = '_';
  99         *p = '\0';
 100
 101         return buf;
 102 }
 103
 104 #define vpr_info(fmt, ...)                                      \
 105 do {                                                            \
 106         if (verbose)                                            \
 107                 pr_info(fmt, ##__VA_ARGS__);                    \
 108 } while (0)
 109
 110 static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
 111 {
 112         /* trim any trailing newlines */
 113         int fmtlen = 0;
 114
 115         if (query->format) {
 116                 fmtlen = strlen(query->format);
 117                 while (fmtlen && query->format[fmtlen - 1] == '\n')
 118                         fmtlen--;
 119         }
 120
 121         vpr_info("%s: func=\"%s\" file=\"%s\" module=\"%s\" format=\"%.*s\" lineno=%u-%u\n",
 122                  msg,
 123                  query->function ? query->function : "",
 124                  query->filename ? query->filename : "",
 125                  query->module ? query->module : "",
 126                  fmtlen, query->format ? query->format : "",
 127                  query->first_lineno, query->last_lineno);
 128 }
 129
 130 /*
 131  * Search the tables for _ddebug's which match the given `query' and
 132  * apply the `flags' and `mask' to them.  Returns number of matching
 133  * callsites, normally the same as number of changes.  If verbose,
 134  * logs the changes.  Takes ddebug_lock.
 135  */
 136 static int ddebug_change(const struct ddebug_query *query,
 137                         unsigned int flags, unsigned int mask)
 138 {
 139         int i;
 140         struct ddebug_table *dt;
 141         unsigned int newflags;
 142         unsigned int nfound = 0;
 143         char flagbuf[10];
 144
 145         /* search for matching ddebugs */
 146         mutex_lock(&ddebug_lock);
 147         list_for_each_entry(dt, &ddebug_tables, link) {
 148
 149                 /* match against the module name */
 150                 if (query->module && strcmp(query->module, dt->mod_name))
 151                         continue;
 152
 153                 for (i = 0; i < dt->num_ddebugs; i++) {
 154                         struct _ddebug *dp = &dt->ddebugs[i];
 155
 156                         /* match against the source filename */
 157                         if (query->filename &&
 158                             strcmp(query->filename, dp->filename) &&
 159                             strcmp(query->filename, kbasename(dp->filename)) &&
 160                             strcmp(query->filename, trim_prefix(dp->filename)))
 161                                 continue;
 162
 163                         /* match against the function */
 164                         if (query->function &&
 165                             strcmp(query->function, dp->function))
 166                                 continue;
 167
 168                         /* match against the format */
 169                         if (query->format &&
 170                             !strstr(dp->format, query->format))
 171                                 continue;
 172
 173                         /* match against the line number range */
 174                         if (query->first_lineno &&
 175                             dp->lineno < query->first_lineno)
 176                                 continue;
 177                         if (query->last_lineno &&
 178                             dp->lineno > query->last_lineno)
 179                                 continue;
 180
 181                         nfound++;
 182
 183                         newflags = (dp->flags & mask) | flags;
 184                         if (newflags == dp->flags)
 185                                 continue;
 186                         dp->flags = newflags;
 187                         vpr_info("changed %s:%d [%s]%s =%s\n",
 188                                  trim_prefix(dp->filename), dp->lineno,
 189                                  dt->mod_name, dp->function,
 190                                  ddebug_describe_flags(dp, flagbuf,
 191                                                        sizeof(flagbuf)));
 192                 }
 193         }
 194         mutex_unlock(&ddebug_lock);
 195
 196         if (!nfound && verbose)
 197                 pr_info("no matches for query\n");
 198
 199         return nfound;
 200 }
 201
 202 /*
 203  * Split the buffer `buf' into space-separated words.
 204  * Handles simple " and ' quoting, i.e. without nested,
 205  * embedded or escaped \".  Return the number of words
 206  * or <0 on error.
 207  */
 208 static int ddebug_tokenize(char *buf, char *words[], int maxwords)
 209 {
 210         int nwords = 0;
 211
 212         while (*buf) {
 213                 char *end;
 214
 215                 /* Skip leading whitespace */
 216                 buf = skip_spaces(buf);
 217                 if (!*buf)
 218                         break;  /* oh, it was trailing whitespace */
 219                 if (*buf == '#')
 220                         break;  /* token starts comment, skip rest of line */
 221
 222                 /* find `end' of word, whitespace separated or quoted */
 223                 if (*buf == '"' || *buf == '\'') {
 224                         int quote = *buf++;
 225                         for (end = buf; *end && *end != quote; end++)
 226                                 ;
 227                         if (!*end) {
 228                                 pr_err("unclosed quote: %s\n", buf);
 229                                 return -EINVAL; /* unclosed quote */
 230                         }
 231                 } else {
 232                         for (end = buf; *end && !isspace(*end); end++)
 233                                 ;
 234                         BUG_ON(end == buf);
 235                 }
 236
 237                 /* `buf' is start of word, `end' is one past its end */
 238                 if (nwords == maxwords) {
 239                         pr_err("too many words, legal max <=%d\n", maxwords);
 240                         return -EINVAL; /* ran out of words[] before bytes */
 241                 }
 242                 if (*end)
 243                         *end++ = '\0';  /* terminate the word */
 244                 words[nwords++] = buf;
 245                 buf = end;
 246         }
 247
 248         if (verbose) {
 249                 int i;
 250                 pr_info("split into words:");
 251                 for (i = 0; i < nwords; i++)
 252                         pr_cont(" \"%s\"", words[i]);
 253                 pr_cont("\n");
 254         }
 255
 256         return nwords;
 257 }
 258
 259 /*
 260  * Parse a single line number.  Note that the empty string ""
 261  * is treated as a special case and converted to zero, which
 262  * is later treated as a "don't care" value.
 263  */
 264 static inline int parse_lineno(const char *str, unsigned int *val)
 265 {
 266         char *end = NULL;
 267         BUG_ON(str == NULL);
 268         if (*str == '\0') {
 269                 *val = 0;
 270                 return 0;
 271         }
 272         *val = simple_strtoul(str, &end, 10);
 273         if (end == NULL || end == str || *end != '\0') {
 274                 pr_err("bad line-number: %s\n", str);
 275                 return -EINVAL;
 276         }
 277         return 0;
 278 }
 279
 280 static int check_set(const char **dest, char *src, char *name)
 281 {
 282         int rc = 0;
 283
 284         if (*dest) {
 285                 rc = -EINVAL;
 286                 pr_err("match-spec:%s val:%s overridden by %s\n",
 287                        name, *dest, src);
 288         }
 289         *dest = src;
 290         return rc;
 291 }
 292
 293 /*
 294  * Parse words[] as a ddebug query specification, which is a series
 295  * of (keyword, value) pairs chosen from these possibilities:
 296  *
 297  * func <function-name>
 298  * file <full-pathname>
 299  * file <base-filename>
 300  * module <module-name>
 301  * format <escaped-string-to-find-in-format>
 302  * line <lineno>
 303  * line <first-lineno>-<last-lineno> // where either may be empty
 304  *
 305  * Only 1 of each type is allowed.
 306  * Returns 0 on success, <0 on error.
 307  */
 308 static int ddebug_parse_query(char *words[], int nwords,
 309                         struct ddebug_query *query, const char *modname)
 310 {
 311         unsigned int i;
 312         int rc;
 313
 314         /* check we have an even number of words */
 315         if (nwords % 2 != 0) {
 316                 pr_err("expecting pairs of match-spec <value>\n");
 317                 return -EINVAL;
 318         }
 319         memset(query, 0, sizeof(*query));
 320
 321         if (modname)
 322                 /* support $modname.dyndbg=<multiple queries> */
 323                 query->module = modname;
 324
 325         for (i = 0; i < nwords; i += 2) {
 326                 if (!strcmp(words[i], "func")) {
 327                         rc = check_set(&query->function, words[i+1], "func");
 328                 } else if (!strcmp(words[i], "file")) {
 329                         rc = check_set(&query->filename, words[i+1], "file");
 330                 } else if (!strcmp(words[i], "module")) {
 331                         rc = check_set(&query->module, words[i+1], "module");
 332                 } else if (!strcmp(words[i], "format")) {
 333                         string_unescape_inplace(words[i+1], UNESCAPE_SPACE |
 334                                                             UNESCAPE_OCTAL |
 335                                                             UNESCAPE_SPECIAL);
 336                         rc = check_set(&query->format, words[i+1], "format");
 337                 } else if (!strcmp(words[i], "line")) {
 338                         char *first = words[i+1];
 339                         char *last = strchr(first, '-');
 340                         if (query->first_lineno || query->last_lineno) {
 341                                 pr_err("match-spec: line used 2x\n");
 342                                 return -EINVAL;
 343                         }
 344                         if (last)
 345                                 *last++ = '\0';
 346                         if (parse_lineno(first, &query->first_lineno) < 0) {
 347                                 pr_err("line-number is <0\n");
 348                                 return -EINVAL;
 349                         }
 350                         if (last) {
 351                                 /* range <first>-<last> */
 352                                 if (parse_lineno(last, &query->last_lineno)
 353                                     < query->first_lineno) {
 354                                         pr_err("last-line:%d < 1st-line:%d\n",
 355                                                 query->last_lineno,
 356                                                 query->first_lineno);
 357                                         return -EINVAL;
 358                                 }
 359                         } else {
 360                                 query->last_lineno = query->first_lineno;
 361                         }
 362                 } else {
 363                         pr_err("unknown keyword \"%s\"\n", words[i]);
 364                         return -EINVAL;
 365                 }
 366                 if (rc)
 367                         return rc;
 368         }
 369         vpr_info_dq(query, "parsed");
 370         return 0;
 371 }
 372
 373 /*
 374  * Parse `str' as a flags specification, format [-+=][p]+.
 375  * Sets up *maskp and *flagsp to be used when changing the
 376  * flags fields of matched _ddebug's.  Returns 0 on success
 377  * or <0 on error.
 378  */
 379 static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 380                                unsigned int *maskp)
 381 {
 382         unsigned flags = 0;
 383         int op = '=', i;
 384
 385         switch (*str) {
 386         case '+':
 387         case '-':
 388         case '=':
 389                 op = *str++;
 390                 break;
 391         default:
 392                 pr_err("bad flag-op %c, at start of %s\n", *str, str);
 393                 return -EINVAL;
 394         }
 395         vpr_info("op='%c'\n", op);
 396
 397         for (; *str ; ++str) {
 398                 for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
 399                         if (*str == opt_array[i].opt_char) {
 400                                 flags |= opt_array[i].flag;
 401                                 break;
 402                         }
 403                 }
 404                 if (i < 0) {
 405                         pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
 406                         return -EINVAL;
 407                 }
 408         }
 409         vpr_info("flags=0x%x\n", flags);
 410
 411         /* calculate final *flagsp, *maskp according to mask and op */
 412         switch (op) {
 413         case '=':
 414                 *maskp = 0;
 415                 *flagsp = flags;
 416                 break;
 417         case '+':
 418                 *maskp = ~0U;
 419                 *flagsp = flags;
 420                 break;
 421         case '-':
 422                 *maskp = ~flags;
 423                 *flagsp = 0;
 424                 break;
 425         }
 426         vpr_info("*flagsp=0x%x *maskp=0x%x\n", *flagsp, *maskp);
 427         return 0;
 428 }
 429
 430 static int ddebug_exec_query(char *query_string, const char *modname)
 431 {
 432         unsigned int flags = 0, mask = 0;
 433         struct ddebug_query query;
 434 #define MAXWORDS 9
 435         int nwords, nfound;
 436         char *words[MAXWORDS];
 437
 438         nwords = ddebug_tokenize(query_string, words, MAXWORDS);
 439         if (nwords <= 0) {
 440                 pr_err("tokenize failed\n");
 441                 return -EINVAL;
 442         }
 443         /* check flags 1st (last arg) so query is pairs of spec,val */
 444         if (ddebug_parse_flags(words[nwords-1], &flags, &mask)) {
 445                 pr_err("flags parse failed\n");
 446                 return -EINVAL;
 447         }
 448         if (ddebug_parse_query(words, nwords-1, &query, modname)) {
 449                 pr_err("query parse failed\n");
 450                 return -EINVAL;
 451         }
 452         /* actually go and implement the change */
 453         nfound = ddebug_change(&query, flags, mask);
 454         vpr_info_dq(&query, nfound ? "applied" : "no-match");
 455
 456         return nfound;
 457 }
 458
 459 /* handle multiple queries in query string, continue on error, return
 460    last error or number of matching callsites.  Module name is either
 461    in param (for boot arg) or perhaps in query string.
 462 */
 463 static int ddebug_exec_queries(char *query, const char *modname)
 464 {
 465         char *split;
 466         int i, errs = 0, exitcode = 0, rc, nfound = 0;
 467
 468         for (i = 0; query; query = split) {
 469                 split = strpbrk(query, ";\n");
 470                 if (split)
 471                         *split++ = '\0';
 472
 473                 query = skip_spaces(query);
 474                 if (!query || !*query || *query == '#')
 475                         continue;
 476
 477                 vpr_info("query %d: \"%s\"\n", i, query);
 478
 479                 rc = ddebug_exec_query(query, modname);
 480                 if (rc < 0) {
 481                         errs++;
 482                         exitcode = rc;
 483                 } else {
 484                         nfound += rc;
 485                 }
 486                 i++;
 487         }
 488         vpr_info("processed %d queries, with %d matches, %d errs\n",
 489                  i, nfound, errs);
 490
 491         if (exitcode)
 492                 return exitcode;
 493         return nfound;
 494 }
 495
 496 #define PREFIX_SIZE 64
 497
 498 static int remaining(int wrote)
 499 {
 500         if (PREFIX_SIZE - wrote > 0)
 501                 return PREFIX_SIZE - wrote;
 502         return 0;
 503 }
 504
 505 static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
 506 {
 507         int pos_after_tid;
 508         int pos = 0;
 509
 510         *buf = '\0';
 511
 512         if (desc->flags & _DPRINTK_FLAGS_INCL_TID) {
 513                 if (in_interrupt())
 514                         pos += snprintf(buf + pos, remaining(pos), "<intr> ");
 515                 else
 516                         pos += snprintf(buf + pos, remaining(pos), "[%d] ",
 517                                         task_pid_vnr(current));
 518         }
 519         pos_after_tid = pos;
 520         if (desc->flags & _DPRINTK_FLAGS_INCL_MODNAME)
 521                 pos += snprintf(buf + pos, remaining(pos), "%s:",
 522                                 desc->modname);
 523         if (desc->flags & _DPRINTK_FLAGS_INCL_FUNCNAME)
 524                 pos += snprintf(buf + pos, remaining(pos), "%s:",
 525                                 desc->function);
 526         if (desc->flags & _DPRINTK_FLAGS_INCL_LINENO)
 527                 pos += snprintf(buf + pos, remaining(pos), "%d:",
 528                                 desc->lineno);
 529         if (pos - pos_after_tid)
 530                 pos += snprintf(buf + pos, remaining(pos), " ");
 531         if (pos >= PREFIX_SIZE)
 532                 buf[PREFIX_SIZE - 1] = '\0';
 533
 534         return buf;
 535 }
 536
 537 int __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...)
 538 {
 539         va_list args;
 540         int res;
 541         struct va_format vaf;
 542         char buf[PREFIX_SIZE];
 543
 544         BUG_ON(!descriptor);
 545         BUG_ON(!fmt);
 546
 547         va_start(args, fmt);
 548
 549         vaf.fmt = fmt;
 550         vaf.va = &args;
 551
 552         res = printk(KERN_DEBUG "%s%pV",
 553                      dynamic_emit_prefix(descriptor, buf), &vaf);
 554
 555         va_end(args);
 556
 557         return res;
 558 }
 559 EXPORT_SYMBOL(__dynamic_pr_debug);
 560
 561 int __dynamic_dev_dbg(struct _ddebug *descriptor,
 562                       const struct device *dev, const char *fmt, ...)
 563 {
 564         struct va_format vaf;
 565         va_list args;
 566         int res;
 567
 568         BUG_ON(!descriptor);
 569         BUG_ON(!fmt);
 570
 571         va_start(args, fmt);
 572
 573         vaf.fmt = fmt;
 574         vaf.va = &args;
 575
 576         if (!dev) {
 577                 res = printk(KERN_DEBUG "(NULL device *): %pV", &vaf);
 578         } else {
 579                 char buf[PREFIX_SIZE];
 580
 581                 res = dev_printk_emit(7, dev, "%s%s %s: %pV",
 582                                       dynamic_emit_prefix(descriptor, buf),
 583                                       dev_driver_string(dev), dev_name(dev),
 584                                       &vaf);
 585         }
 586
 587         va_end(args);
 588
 589         return res;
 590 }
 591 EXPORT_SYMBOL(__dynamic_dev_dbg);
 592
 593 #ifdef CONFIG_NET
 594
 595 int __dynamic_netdev_dbg(struct _ddebug *descriptor,
 596                          const struct net_device *dev, const char *fmt, ...)
 597 {
 598         struct va_format vaf;
 599         va_list args;
 600         int res;
 601
 602         BUG_ON(!descriptor);
 603         BUG_ON(!fmt);
 604
 605         va_start(args, fmt);
 606
 607         vaf.fmt = fmt;
 608         vaf.va = &args;
 609
 610         if (dev && dev->dev.parent) {
 611                 char buf[PREFIX_SIZE];
 612
 613                 res = dev_printk_emit(7, dev->dev.parent,
 614                                       "%s%s %s %s: %pV",
 615                                       dynamic_emit_prefix(descriptor, buf),
 616                                       dev_driver_string(dev->dev.parent),
 617                                       dev_name(dev->dev.parent),
 618                                       netdev_name(dev), &vaf);
 619         } else if (dev) {
 620                 res = printk(KERN_DEBUG "%s: %pV", netdev_name(dev), &vaf);
 621         } else {
 622                 res = printk(KERN_DEBUG "(NULL net_device): %pV", &vaf);
 623         }
 624
 625         va_end(args);
 626
 627         return res;
 628 }
 629 EXPORT_SYMBOL(__dynamic_netdev_dbg);
 630
 631 #endif
 632
 633 #define DDEBUG_STRING_SIZE 1024
 634 static __initdata char ddebug_setup_string[DDEBUG_STRING_SIZE];
 635
 636 static __init int ddebug_setup_query(char *str)
 637 {
 638         if (strlen(str) >= DDEBUG_STRING_SIZE) {
 639                 pr_warn("ddebug boot param string too large\n");
 640                 return 0;
 641         }
 642         strlcpy(ddebug_setup_string, str, DDEBUG_STRING_SIZE);
 643         return 1;
 644 }
 645
 646 __setup("ddebug_query=", ddebug_setup_query);
 647
 648 /*
 649  * File_ops->write method for <debugfs>/dynamic_debug/conrol.  Gathers the
 650  * command text from userspace, parses and executes it.
 651  */
 652 #define USER_BUF_PAGE 4096
 653 static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
 654                                   size_t len, loff_t *offp)
 655 {
 656         char *tmpbuf;
 657         int ret;
 658
 659         if (len == 0)
 660                 return 0;
 661         if (len > USER_BUF_PAGE - 1) {
 662                 pr_warn("expected <%d bytes into control\n", USER_BUF_PAGE);
 663                 return -E2BIG;
 664         }
 665         tmpbuf = kmalloc(len + 1, GFP_KERNEL);
 666         if (!tmpbuf)
 667                 return -ENOMEM;
 668         if (copy_from_user(tmpbuf, ubuf, len)) {
 669                 kfree(tmpbuf);
 670                 return -EFAULT;
 671         }
 672         tmpbuf[len] = '\0';
 673         vpr_info("read %d bytes from userspace\n", (int)len);
 674
 675         ret = ddebug_exec_queries(tmpbuf, NULL);
 676         kfree(tmpbuf);
 677         if (ret < 0)
 678                 return ret;
 679
 680         *offp += len;
 681         return len;
 682 }
 683
 684 /*
 685  * Set the iterator to point to the first _ddebug object
 686  * and return a pointer to that first object.  Returns
 687  * NULL if there are no _ddebugs at all.
 688  */
 689 static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
 690 {
 691         if (list_empty(&ddebug_tables)) {
 692                 iter->table = NULL;
 693                 iter->idx = 0;
 694                 return NULL;
 695         }
 696         iter->table = list_entry(ddebug_tables.next,
 697                                  struct ddebug_table, link);
 698         iter->idx = 0;
 699         return &iter->table->ddebugs[iter->idx];
 700 }
 701
 702 /*
 703  * Advance the iterator to point to the next _ddebug
 704  * object from the one the iterator currently points at,
 705  * and returns a pointer to the new _ddebug.  Returns
 706  * NULL if the iterator has seen all the _ddebugs.
 707  */
 708 static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
 709 {
 710         if (iter->table == NULL)
 711                 return NULL;
 712         if (++iter->idx == iter->table->num_ddebugs) {
 713                 /* iterate to next table */
 714                 iter->idx = 0;
 715                 if (list_is_last(&iter->table->link, &ddebug_tables)) {
 716                         iter->table = NULL;
 717                         return NULL;
 718                 }
 719                 iter->table = list_entry(iter->table->link.next,
 720                                          struct ddebug_table, link);
 721         }
 722         return &iter->table->ddebugs[iter->idx];
 723 }
 724
 725 /*
 726  * Seq_ops start method.  Called at the start of every
 727  * read() call from userspace.  Takes the ddebug_lock and
 728  * seeks the seq_file's iterator to the given position.
 729  */
 730 static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
 731 {
 732         struct ddebug_iter *iter = m->private;
 733         struct _ddebug *dp;
 734         int n = *pos;
 735
 736         vpr_info("called m=%p *pos=%lld\n", m, (unsigned long long)*pos);
 737
 738         mutex_lock(&ddebug_lock);
 739
 740         if (!n)
 741                 return SEQ_START_TOKEN;
 742         if (n < 0)
 743                 return NULL;
 744         dp = ddebug_iter_first(iter);
 745         while (dp != NULL && --n > 0)
 746                 dp = ddebug_iter_next(iter);
 747         return dp;
 748 }
 749
 750 /*
 751  * Seq_ops next method.  Called several times within a read()
 752  * call from userspace, with ddebug_lock held.  Walks to the
 753  * next _ddebug object with a special case for the header line.
 754  */
 755 static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
 756 {
 757         struct ddebug_iter *iter = m->private;
 758         struct _ddebug *dp;
 759
 760         vpr_info("called m=%p p=%p *pos=%lld\n",
 761                  m, p, (unsigned long long)*pos);
 762
 763         if (p == SEQ_START_TOKEN)
 764                 dp = ddebug_iter_first(iter);
 765         else
 766                 dp = ddebug_iter_next(iter);
 767         ++*pos;
 768         return dp;
 769 }
 770
 771 /*
 772  * Seq_ops show method.  Called several times within a read()
 773  * call from userspace, with ddebug_lock held.  Formats the
 774  * current _ddebug as a single human-readable line, with a
 775  * special case for the header line.
 776  */
 777 static int ddebug_proc_show(struct seq_file *m, void *p)
 778 {
 779         struct ddebug_iter *iter = m->private;
 780         struct _ddebug *dp = p;
 781         char flagsbuf[10];
 782
 783         vpr_info("called m=%p p=%p\n", m, p);
 784
 785         if (p == SEQ_START_TOKEN) {
 786                 seq_puts(m,
 787                          "# filename:lineno [module]function flags format\n");
 788                 return 0;
 789         }
 790
 791         seq_printf(m, "%s:%u [%s]%s =%s \"",
 792                    trim_prefix(dp->filename), dp->lineno,
 793                    iter->table->mod_name, dp->function,
 794                    ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
 795         seq_escape(m, dp->format, "\t\r\n\"");
 796         seq_puts(m, "\"\n");
 797
 798         return 0;
 799 }
 800
 801 /*
 802  * Seq_ops stop method.  Called at the end of each read()
 803  * call from userspace.  Drops ddebug_lock.
 804  */
 805 static void ddebug_proc_stop(struct seq_file *m, void *p)
 806 {
 807         vpr_info("called m=%p p=%p\n", m, p);
 808         mutex_unlock(&ddebug_lock);
 809 }
 810
 811 static const struct seq_operations ddebug_proc_seqops = {
 812         .start = ddebug_proc_start,
 813         .next = ddebug_proc_next,
 814         .show = ddebug_proc_show,
 815         .stop = ddebug_proc_stop
 816 };
 817
 818 /*
 819  * File_ops->open method for <debugfs>/dynamic_debug/control.  Does
 820  * the seq_file setup dance, and also creates an iterator to walk the
 821  * _ddebugs.  Note that we create a seq_file always, even for O_WRONLY
 822  * files where it's not needed, as doing so simplifies the ->release
 823  * method.
 824  */
 825 static int ddebug_proc_open(struct inode *inode, struct file *file)
 826 {
 827         struct ddebug_iter *iter;
 828         int err;
 829
 830         vpr_info("called\n");
 831
 832         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
 833         if (iter == NULL)
 834                 return -ENOMEM;
 835
 836         err = seq_open(file, &ddebug_proc_seqops);
 837         if (err) {
 838                 kfree(iter);
 839                 return err;
 840         }
 841         ((struct seq_file *)file->private_data)->private = iter;
 842         return 0;
 843 }
 844
 845 static const struct file_operations ddebug_proc_fops = {
 846         .owner = THIS_MODULE,
 847         .open = ddebug_proc_open,
 848         .read = seq_read,
 849         .llseek = seq_lseek,
 850         .release = seq_release_private,
 851         .write = ddebug_proc_write
 852 };
 853
 854 /*
 855  * Allocate a new ddebug_table for the given module
 856  * and add it to the global list.
 857  */
 858 int ddebug_add_module(struct _ddebug *tab, unsigned int n,
 859                              const char *name)
 860 {
 861         struct ddebug_table *dt;
 862         char *new_name;
 863
 864         dt = kzalloc(sizeof(*dt), GFP_KERNEL);
 865         if (dt == NULL)
 866                 return -ENOMEM;
 867         new_name = kstrdup(name, GFP_KERNEL);
 868         if (new_name == NULL) {
 869                 kfree(dt);
 870                 return -ENOMEM;
 871         }
 872         dt->mod_name = new_name;
 873         dt->num_ddebugs = n;
 874         dt->ddebugs = tab;
 875
 876         mutex_lock(&ddebug_lock);
 877         list_add_tail(&dt->link, &ddebug_tables);
 878         mutex_unlock(&ddebug_lock);
 879
 880         vpr_info("%u debug prints in module %s\n", n, dt->mod_name);
 881         return 0;
 882 }
 883 EXPORT_SYMBOL_GPL(ddebug_add_module);
 884
 885 /* helper for ddebug_dyndbg_(boot|module)_param_cb */
 886 static int ddebug_dyndbg_param_cb(char *param, char *val,
 887                                 const char *modname, int on_err)
 888 {
 889         char *sep;
 890
 891         sep = strchr(param, '.');
 892         if (sep) {
 893                 /* needed only for ddebug_dyndbg_boot_param_cb */
 894                 *sep = '\0';
 895                 modname = param;
 896                 param = sep + 1;
 897         }
 898         if (strcmp(param, "dyndbg"))
 899                 return on_err; /* determined by caller */
 900
 901         ddebug_exec_queries((val ? val : "+p"), modname);
 902
 903         return 0; /* query failure shouldnt stop module load */
 904 }
 905
 906 /* handle both dyndbg and $module.dyndbg params at boot */
 907 static int ddebug_dyndbg_boot_param_cb(char *param, char *val,
 908                                 const char *unused)
 909 {
 910         vpr_info("%s=\"%s\"\n", param, val);
 911         return ddebug_dyndbg_param_cb(param, val, NULL, 0);
 912 }
 913
 914 /*
 915  * modprobe foo finds foo.params in boot-args, strips "foo.", and
 916  * passes them to load_module().  This callback gets unknown params,
 917  * processes dyndbg params, rejects others.
 918  */
 919 int ddebug_dyndbg_module_param_cb(char *param, char *val, const char *module)
 920 {
 921         vpr_info("module: %s %s=\"%s\"\n", module, param, val);
 922         return ddebug_dyndbg_param_cb(param, val, module, -ENOENT);
 923 }
 924
 925 static void ddebug_table_free(struct ddebug_table *dt)
 926 {
 927         list_del_init(&dt->link);
 928         kfree(dt->mod_name);
 929         kfree(dt);
 930 }
 931
 932 /*
 933  * Called in response to a module being unloaded.  Removes
 934  * any ddebug_table's which point at the module.
 935  */
 936 int ddebug_remove_module(const char *mod_name)
 937 {
 938         struct ddebug_table *dt, *nextdt;
 939         int ret = -ENOENT;
 940
 941         vpr_info("removing module \"%s\"\n", mod_name);
 942
 943         mutex_lock(&ddebug_lock);
 944         list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
 945                 if (!strcmp(dt->mod_name, mod_name)) {
 946                         ddebug_table_free(dt);
 947                         ret = 0;
 948                 }
 949         }
 950         mutex_unlock(&ddebug_lock);
 951         return ret;
 952 }
 953 EXPORT_SYMBOL_GPL(ddebug_remove_module);
 954
 955 static void ddebug_remove_all_tables(void)
 956 {
 957         mutex_lock(&ddebug_lock);
 958         while (!list_empty(&ddebug_tables)) {
 959                 struct ddebug_table *dt = list_entry(ddebug_tables.next,
 960                                                       struct ddebug_table,
 961                                                       link);
 962                 ddebug_table_free(dt);
 963         }
 964         mutex_unlock(&ddebug_lock);
 965 }
 966
 967 static __initdata int ddebug_init_success;
 968
 969 static int __init dynamic_debug_init_debugfs(void)
 970 {
 971         struct dentry *dir, *file;
 972
 973         if (!ddebug_init_success)
 974                 return -ENODEV;
 975
 976         dir = debugfs_create_dir("dynamic_debug", NULL);
 977         if (!dir)
 978                 return -ENOMEM;
 979         file = debugfs_create_file("control", 0644, dir, NULL,
 980                                         &ddebug_proc_fops);
 981         if (!file) {
 982                 debugfs_remove(dir);
 983                 return -ENOMEM;
 984         }
 985         return 0;
 986 }
 987
 988 static int __init dynamic_debug_init(void)
 989 {
 990         struct _ddebug *iter, *iter_start;
 991         const char *modname = NULL;
 992         char *cmdline;
 993         int ret = 0;
 994         int n = 0, entries = 0, modct = 0;
 995         int verbose_bytes = 0;
 996
 997         if (__start___verbose == __stop___verbose) {
 998                 pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
 999                 return 1;
1000         }
1001         iter = __start___verbose;
1002         modname = iter->modname;
1003         iter_start = iter;
1004         for (; iter < __stop___verbose; iter++) {
1005                 entries++;
1006                 verbose_bytes += strlen(iter->modname) + strlen(iter->function)
1007                         + strlen(iter->filename) + strlen(iter->format);
1008
1009                 if (strcmp(modname, iter->modname)) {
1010                         modct++;
1011                         ret = ddebug_add_module(iter_start, n, modname);
1012                         if (ret)
1013                                 goto out_err;
1014                         n = 0;
1015                         modname = iter->modname;
1016                         iter_start = iter;
1017                 }
1018                 n++;
1019         }
1020         ret = ddebug_add_module(iter_start, n, modname);
1021         if (ret)
1022                 goto out_err;
1023
1024         ddebug_init_success = 1;
1025         vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in (readonly) verbose section\n",
1026                  modct, entries, (int)(modct * sizeof(struct ddebug_table)),
1027                  verbose_bytes + (int)(__stop___verbose - __start___verbose));
1028
1029         /* apply ddebug_query boot param, dont unload tables on err */
1030         if (ddebug_setup_string[0] != '\0') {
1031                 pr_warn("ddebug_query param name is deprecated, change it to dyndbg\n");
1032                 ret = ddebug_exec_queries(ddebug_setup_string, NULL);
1033                 if (ret < 0)
1034                         pr_warn("Invalid ddebug boot param %s\n",
1035                                 ddebug_setup_string);
1036                 else
1037                         pr_info("%d changes by ddebug_query\n", ret);
1038         }
1039         /* now that ddebug tables are loaded, process all boot args
1040          * again to find and activate queries given in dyndbg params.
1041          * While this has already been done for known boot params, it
1042          * ignored the unknown ones (dyndbg in particular).  Reusing
1043          * parse_args avoids ad-hoc parsing.  This will also attempt
1044          * to activate queries for not-yet-loaded modules, which is
1045          * slightly noisy if verbose, but harmless.
1046          */
1047         cmdline = kstrdup(saved_command_line, GFP_KERNEL);
1048         parse_args("dyndbg params", cmdline, NULL,
1049                    0, 0, 0, &ddebug_dyndbg_boot_param_cb);
1050         kfree(cmdline);
1051         return 0;
1052
1053 out_err:
1054         ddebug_remove_all_tables();
1055         return 0;
1056 }
1057 /* Allow early initialization for boot messages via boot param */
1058 early_initcall(dynamic_debug_init);
1059
1060 /* Debugfs setup must be done later */
1061 fs_initcall(dynamic_debug_init_debugfs);