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/uaccess.h>
  28 #include <linux/dynamic_debug.h>
  29 #include <linux/debugfs.h>
  30 #include <linux/slab.h>
  31 #include <linux/jump_label.h>
  32 #include <linux/hardirq.h>
  33 #include <linux/sched.h>
  34 #include <linux/device.h>
  35 #include <linux/netdevice.h>
  36
  37 extern struct _ddebug __start___verbose[];
  38 extern struct _ddebug __stop___verbose[];
  39
  40 struct ddebug_table {
  41         struct list_head link;
  42         char *mod_name;
  43         unsigned int num_ddebugs;
  44         struct _ddebug *ddebugs;
  45 };
  46
  47 struct ddebug_query {
  48         const char *filename;
  49         const char *module;
  50         const char *function;
  51         const char *format;
  52         unsigned int first_lineno, last_lineno;
  53 };
  54
  55 struct ddebug_iter {
  56         struct ddebug_table *table;
  57         unsigned int idx;
  58 };
  59
  60 static DEFINE_MUTEX(ddebug_lock);
  61 static LIST_HEAD(ddebug_tables);
  62 static int verbose = 0;
  63 module_param(verbose, int, 0644);
  64
  65 /* Return the last part of a pathname */
  66 static inline const char *basename(const char *path)
  67 {
  68         const char *tail = strrchr(path, '/');
  69         return tail ? tail+1 : path;
  70 }
  71
  72 /* Return the path relative to source root */
  73 static inline const char *trim_prefix(const char *path)
  74 {
  75         int skip = strlen(__FILE__) - strlen("lib/dynamic_debug.c");
  76
  77         if (strncmp(path, __FILE__, skip))
  78                 skip = 0; /* prefix mismatch, don't skip */
  79
  80         return path + skip;
  81 }
  82
  83 static struct { unsigned flag:8; char opt_char; } opt_array[] = {
  84         { _DPRINTK_FLAGS_PRINT, 'p' },
  85         { _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
  86         { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
  87         { _DPRINTK_FLAGS_INCL_LINENO, 'l' },
  88         { _DPRINTK_FLAGS_INCL_TID, 't' },
  89         { _DPRINTK_FLAGS_NONE, '_' },
  90 };
  91
  92 /* format a string into buf[] which describes the _ddebug's flags */
  93 static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
  94                                     size_t maxlen)
  95 {
  96         char *p = buf;
  97         int i;
  98
  99         BUG_ON(maxlen < 6);
 100         for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
 101                 if (dp->flags & opt_array[i].flag)
 102                         *p++ = opt_array[i].opt_char;
 103         if (p == buf)
 104                 *p++ = '_';
 105         *p = '\0';
 106
 107         return buf;
 108 }
 109
 110 #define vpr_info(fmt, ...) \
 111         if (verbose) do { pr_info(fmt, ##__VA_ARGS__); } while (0)
 112
 113 #define vpr_info_dq(q, msg)                                     \
 114 do {                                                            \
 115         /* trim last char off format print */                   \
 116         vpr_info("%s: func=\"%s\" file=\"%s\" "                 \
 117                 "module=\"%s\" format=\"%.*s\" "                \
 118                 "lineno=%u-%u",                                 \
 119                 msg,                                            \
 120                 q->function ? q->function : "",                 \
 121                 q->filename ? q->filename : "",                 \
 122                 q->module ? q->module : "",                     \
 123                 (int)(q->format ? strlen(q->format) - 1 : 0),   \
 124                 q->format ? q->format : "",                     \
 125                 q->first_lineno, q->last_lineno);               \
 126 } while (0)
 127
 128 /*
 129  * Search the tables for _ddebug's which match the given `query' and
 130  * apply the `flags' and `mask' to them.  Returns number of matching
 131  * callsites, normally the same as number of changes.  If verbose,
 132  * logs the changes.  Takes ddebug_lock.
 133  */
 134 static int ddebug_change(const struct ddebug_query *query,
 135                         unsigned int flags, unsigned int mask)
 136 {
 137         int i;
 138         struct ddebug_table *dt;
 139         unsigned int newflags;
 140         unsigned int nfound = 0;
 141         char flagbuf[10];
 142
 143         /* search for matching ddebugs */
 144         mutex_lock(&ddebug_lock);
 145         list_for_each_entry(dt, &ddebug_tables, link) {
 146
 147                 /* match against the module name */
 148                 if (query->module && strcmp(query->module, dt->mod_name))
 149                         continue;
 150
 151                 for (i = 0 ; i < dt->num_ddebugs ; i++) {
 152                         struct _ddebug *dp = &dt->ddebugs[i];
 153
 154                         /* match against the source filename */
 155                         if (query->filename &&
 156                             strcmp(query->filename, dp->filename) &&
 157                             strcmp(query->filename, basename(dp->filename)) &&
 158                             strcmp(query->filename, trim_prefix(dp->filename)))
 159                                 continue;
 160
 161                         /* match against the function */
 162                         if (query->function &&
 163                             strcmp(query->function, dp->function))
 164                                 continue;
 165
 166                         /* match against the format */
 167                         if (query->format &&
 168                             !strstr(dp->format, query->format))
 169                                 continue;
 170
 171                         /* match against the line number range */
 172                         if (query->first_lineno &&
 173                             dp->lineno < query->first_lineno)
 174                                 continue;
 175                         if (query->last_lineno &&
 176                             dp->lineno > query->last_lineno)
 177                                 continue;
 178
 179                         nfound++;
 180
 181                         newflags = (dp->flags & mask) | flags;
 182                         if (newflags == dp->flags)
 183                                 continue;
 184                         dp->flags = newflags;
 185                         vpr_info("changed %s:%d [%s]%s =%s\n",
 186                                 trim_prefix(dp->filename), dp->lineno,
 187                                 dt->mod_name, dp->function,
 188                                 ddebug_describe_flags(dp, flagbuf,
 189                                                 sizeof(flagbuf)));
 190                 }
 191         }
 192         mutex_unlock(&ddebug_lock);
 193
 194         if (!nfound && verbose)
 195                 pr_info("no matches for query\n");
 196
 197         return nfound;
 198 }
 199
 200 /*
 201  * Split the buffer `buf' into space-separated words.
 202  * Handles simple " and ' quoting, i.e. without nested,
 203  * embedded or escaped \".  Return the number of words
 204  * or <0 on error.
 205  */
 206 static int ddebug_tokenize(char *buf, char *words[], int maxwords)
 207 {
 208         int nwords = 0;
 209
 210         while (*buf) {
 211                 char *end;
 212
 213                 /* Skip leading whitespace */
 214                 buf = skip_spaces(buf);
 215                 if (!*buf)
 216                         break;  /* oh, it was trailing whitespace */
 217                 if (*buf == '#')
 218                         break;  /* token starts comment, skip rest of line */
 219
 220                 /* find `end' of word, whitespace separated or quoted */
 221                 if (*buf == '"' || *buf == '\'') {
 222                         int quote = *buf++;
 223                         for (end = buf ; *end && *end != quote ; end++)
 224                                 ;
 225                         if (!*end)
 226                                 return -EINVAL; /* unclosed quote */
 227                 } else {
 228                         for (end = buf ; *end && !isspace(*end) ; end++)
 229                                 ;
 230                         BUG_ON(end == buf);
 231                 }
 232
 233                 /* `buf' is start of word, `end' is one past its end */
 234                 if (nwords == maxwords)
 235                         return -EINVAL; /* ran out of words[] before bytes */
 236                 if (*end)
 237                         *end++ = '\0';  /* terminate the word */
 238                 words[nwords++] = buf;
 239                 buf = end;
 240         }
 241
 242         if (verbose) {
 243                 int i;
 244                 pr_info("split into words:");
 245                 for (i = 0 ; i < nwords ; i++)
 246                         pr_cont(" \"%s\"", words[i]);
 247                 pr_cont("\n");
 248         }
 249
 250         return nwords;
 251 }
 252
 253 /*
 254  * Parse a single line number.  Note that the empty string ""
 255  * is treated as a special case and converted to zero, which
 256  * is later treated as a "don't care" value.
 257  */
 258 static inline int parse_lineno(const char *str, unsigned int *val)
 259 {
 260         char *end = NULL;
 261         BUG_ON(str == NULL);
 262         if (*str == '\0') {
 263                 *val = 0;
 264                 return 0;
 265         }
 266         *val = simple_strtoul(str, &end, 10);
 267         return end == NULL || end == str || *end != '\0' ? -EINVAL : 0;
 268 }
 269
 270 /*
 271  * Undo octal escaping in a string, inplace.  This is useful to
 272  * allow the user to express a query which matches a format
 273  * containing embedded spaces.
 274  */
 275 #define isodigit(c)             ((c) >= '0' && (c) <= '7')
 276 static char *unescape(char *str)
 277 {
 278         char *in = str;
 279         char *out = str;
 280
 281         while (*in) {
 282                 if (*in == '\\') {
 283                         if (in[1] == '\\') {
 284                                 *out++ = '\\';
 285                                 in += 2;
 286                                 continue;
 287                         } else if (in[1] == 't') {
 288                                 *out++ = '\t';
 289                                 in += 2;
 290                                 continue;
 291                         } else if (in[1] == 'n') {
 292                                 *out++ = '\n';
 293                                 in += 2;
 294                                 continue;
 295                         } else if (isodigit(in[1]) &&
 296                                  isodigit(in[2]) &&
 297                                  isodigit(in[3])) {
 298                                 *out++ = ((in[1] - '0')<<6) |
 299                                           ((in[2] - '0')<<3) |
 300                                           (in[3] - '0');
 301                                 in += 4;
 302                                 continue;
 303                         }
 304                 }
 305                 *out++ = *in++;
 306         }
 307         *out = '\0';
 308
 309         return str;
 310 }
 311
 312 static int check_set(const char **dest, char *src, char *name)
 313 {
 314         int rc = 0;
 315
 316         if (*dest) {
 317                 rc = -EINVAL;
 318                 pr_err("match-spec:%s val:%s overridden by %s",
 319                         name, *dest, src);
 320         }
 321         *dest = src;
 322         return rc;
 323 }
 324
 325 /*
 326  * Parse words[] as a ddebug query specification, which is a series
 327  * of (keyword, value) pairs chosen from these possibilities:
 328  *
 329  * func <function-name>
 330  * file <full-pathname>
 331  * file <base-filename>
 332  * module <module-name>
 333  * format <escaped-string-to-find-in-format>
 334  * line <lineno>
 335  * line <first-lineno>-<last-lineno> // where either may be empty
 336  *
 337  * Only 1 of each type is allowed.
 338  * Returns 0 on success, <0 on error.
 339  */
 340 static int ddebug_parse_query(char *words[], int nwords,
 341                                struct ddebug_query *query)
 342 {
 343         unsigned int i;
 344         int rc;
 345
 346         /* check we have an even number of words */
 347         if (nwords % 2 != 0)
 348                 return -EINVAL;
 349         memset(query, 0, sizeof(*query));
 350
 351         for (i = 0 ; i < nwords ; i += 2) {
 352                 if (!strcmp(words[i], "func"))
 353                         rc = check_set(&query->function, words[i+1], "func");
 354                 else if (!strcmp(words[i], "file"))
 355                         rc = check_set(&query->filename, words[i+1], "file");
 356                 else if (!strcmp(words[i], "module"))
 357                         rc = check_set(&query->module, words[i+1], "module");
 358                 else if (!strcmp(words[i], "format"))
 359                         rc = check_set(&query->format, unescape(words[i+1]),
 360                                 "format");
 361                 else if (!strcmp(words[i], "line")) {
 362                         char *first = words[i+1];
 363                         char *last = strchr(first, '-');
 364                         if (query->first_lineno || query->last_lineno) {
 365                                 pr_err("match-spec:line given 2 times\n");
 366                                 return -EINVAL;
 367                         }
 368                         if (last)
 369                                 *last++ = '\0';
 370                         if (parse_lineno(first, &query->first_lineno) < 0)
 371                                 return -EINVAL;
 372                         if (last) {
 373                                 /* range <first>-<last> */
 374                                 if (parse_lineno(last, &query->last_lineno)
 375                                     < query->first_lineno) {
 376                                         pr_err("last-line < 1st-line\n");
 377                                         return -EINVAL;
 378                                 }
 379                         } else {
 380                                 query->last_lineno = query->first_lineno;
 381                         }
 382                 } else {
 383                         pr_err("unknown keyword \"%s\"\n", words[i]);
 384                         return -EINVAL;
 385                 }
 386                 if (rc)
 387                         return rc;
 388         }
 389         vpr_info_dq(query, "parsed");
 390         return 0;
 391 }
 392
 393 /*
 394  * Parse `str' as a flags specification, format [-+=][p]+.
 395  * Sets up *maskp and *flagsp to be used when changing the
 396  * flags fields of matched _ddebug's.  Returns 0 on success
 397  * or <0 on error.
 398  */
 399 static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 400                                unsigned int *maskp)
 401 {
 402         unsigned flags = 0;
 403         int op = '=', i;
 404
 405         switch (*str) {
 406         case '+':
 407         case '-':
 408         case '=':
 409                 op = *str++;
 410                 break;
 411         default:
 412                 return -EINVAL;
 413         }
 414         vpr_info("op='%c'\n", op);
 415
 416         for ( ; *str ; ++str) {
 417                 for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
 418                         if (*str == opt_array[i].opt_char) {
 419                                 flags |= opt_array[i].flag;
 420                                 break;
 421                         }
 422                 }
 423                 if (i < 0)
 424                         return -EINVAL;
 425         }
 426         vpr_info("flags=0x%x\n", flags);
 427
 428         /* calculate final *flagsp, *maskp according to mask and op */
 429         switch (op) {
 430         case '=':
 431                 *maskp = 0;
 432                 *flagsp = flags;
 433                 break;
 434         case '+':
 435                 *maskp = ~0U;
 436                 *flagsp = flags;
 437                 break;
 438         case '-':
 439                 *maskp = ~flags;
 440                 *flagsp = 0;
 441                 break;
 442         }
 443         vpr_info("*flagsp=0x%x *maskp=0x%x\n", *flagsp, *maskp);
 444         return 0;
 445 }
 446
 447 static int ddebug_exec_query(char *query_string)
 448 {
 449         unsigned int flags = 0, mask = 0;
 450         struct ddebug_query query;
 451 #define MAXWORDS 9
 452         int nwords, nfound;
 453         char *words[MAXWORDS];
 454
 455         nwords = ddebug_tokenize(query_string, words, MAXWORDS);
 456         if (nwords <= 0)
 457                 return -EINVAL;
 458         if (ddebug_parse_query(words, nwords-1, &query))
 459                 return -EINVAL;
 460         if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
 461                 return -EINVAL;
 462
 463         /* actually go and implement the change */
 464         nfound = ddebug_change(&query, flags, mask);
 465         vpr_info_dq((&query), (nfound) ? "applied" : "no-match");
 466
 467         return nfound;
 468 }
 469
 470 /* handle multiple queries in query string, continue on error, return
 471    last error or number of matching callsites.  Module name is either
 472    in param (for boot arg) or perhaps in query string.
 473 */
 474 static int ddebug_exec_queries(char *query)
 475 {
 476         char *split;
 477         int i, errs = 0, exitcode = 0, rc, nfound = 0;
 478
 479         for (i = 0; query; query = split) {
 480                 split = strpbrk(query, ";\n");
 481                 if (split)
 482                         *split++ = '\0';
 483
 484                 query = skip_spaces(query);
 485                 if (!query || !*query || *query == '#')
 486                         continue;
 487
 488                 vpr_info("query %d: \"%s\"\n", i, query);
 489
 490                 rc = ddebug_exec_query(query);
 491                 if (rc < 0) {
 492                         errs++;
 493                         exitcode = rc;
 494                 } else
 495                         nfound += rc;
 496                 i++;
 497         }
 498         vpr_info("processed %d queries, with %d matches, %d errs\n",
 499                  i, nfound, errs);
 500
 501         if (exitcode)
 502                 return exitcode;
 503         return nfound;
 504 }
 505
 506 #define PREFIX_SIZE 64
 507
 508 static int remaining(int wrote)
 509 {
 510         if (PREFIX_SIZE - wrote > 0)
 511                 return PREFIX_SIZE - wrote;
 512         return 0;
 513 }
 514
 515 static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
 516 {
 517         int pos_after_tid;
 518         int pos = 0;
 519
 520         pos += snprintf(buf + pos, remaining(pos), "%s", KERN_DEBUG);
 521         if (desc->flags & _DPRINTK_FLAGS_INCL_TID) {
 522                 if (in_interrupt())
 523                         pos += snprintf(buf + pos, remaining(pos), "%s ",
 524                                                 "<intr>");
 525                 else
 526                         pos += snprintf(buf + pos, remaining(pos), "[%d] ",
 527                                                 task_pid_vnr(current));
 528         }
 529         pos_after_tid = pos;
 530         if (desc->flags & _DPRINTK_FLAGS_INCL_MODNAME)
 531                 pos += snprintf(buf + pos, remaining(pos), "%s:",
 532                                         desc->modname);
 533         if (desc->flags & _DPRINTK_FLAGS_INCL_FUNCNAME)
 534                 pos += snprintf(buf + pos, remaining(pos), "%s:",
 535                                         desc->function);
 536         if (desc->flags & _DPRINTK_FLAGS_INCL_LINENO)
 537                 pos += snprintf(buf + pos, remaining(pos), "%d:",
 538                                         desc->lineno);
 539         if (pos - pos_after_tid)
 540                 pos += snprintf(buf + pos, remaining(pos), " ");
 541         if (pos >= PREFIX_SIZE)
 542                 buf[PREFIX_SIZE - 1] = '\0';
 543
 544         return buf;
 545 }
 546
 547 int __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...)
 548 {
 549         va_list args;
 550         int res;
 551         struct va_format vaf;
 552         char buf[PREFIX_SIZE];
 553
 554         BUG_ON(!descriptor);
 555         BUG_ON(!fmt);
 556
 557         va_start(args, fmt);
 558         vaf.fmt = fmt;
 559         vaf.va = &args;
 560         res = printk("%s%pV", dynamic_emit_prefix(descriptor, buf), &vaf);
 561         va_end(args);
 562
 563         return res;
 564 }
 565 EXPORT_SYMBOL(__dynamic_pr_debug);
 566
 567 int __dynamic_dev_dbg(struct _ddebug *descriptor,
 568                       const struct device *dev, const char *fmt, ...)
 569 {
 570         struct va_format vaf;
 571         va_list args;
 572         int res;
 573         char buf[PREFIX_SIZE];
 574
 575         BUG_ON(!descriptor);
 576         BUG_ON(!fmt);
 577
 578         va_start(args, fmt);
 579         vaf.fmt = fmt;
 580         vaf.va = &args;
 581         res = __dev_printk(dynamic_emit_prefix(descriptor, buf), dev, &vaf);
 582         va_end(args);
 583
 584         return res;
 585 }
 586 EXPORT_SYMBOL(__dynamic_dev_dbg);
 587
 588 #ifdef CONFIG_NET
 589
 590 int __dynamic_netdev_dbg(struct _ddebug *descriptor,
 591                       const struct net_device *dev, const char *fmt, ...)
 592 {
 593         struct va_format vaf;
 594         va_list args;
 595         int res;
 596         char buf[PREFIX_SIZE];
 597
 598         BUG_ON(!descriptor);
 599         BUG_ON(!fmt);
 600
 601         va_start(args, fmt);
 602         vaf.fmt = fmt;
 603         vaf.va = &args;
 604         res = __netdev_printk(dynamic_emit_prefix(descriptor, buf), dev, &vaf);
 605         va_end(args);
 606
 607         return res;
 608 }
 609 EXPORT_SYMBOL(__dynamic_netdev_dbg);
 610
 611 #endif
 612
 613 #define DDEBUG_STRING_SIZE 1024
 614 static __initdata char ddebug_setup_string[DDEBUG_STRING_SIZE];
 615
 616 static __init int ddebug_setup_query(char *str)
 617 {
 618         if (strlen(str) >= DDEBUG_STRING_SIZE) {
 619                 pr_warn("ddebug boot param string too large\n");
 620                 return 0;
 621         }
 622         strlcpy(ddebug_setup_string, str, DDEBUG_STRING_SIZE);
 623         return 1;
 624 }
 625
 626 __setup("ddebug_query=", ddebug_setup_query);
 627
 628 /*
 629  * File_ops->write method for <debugfs>/dynamic_debug/conrol.  Gathers the
 630  * command text from userspace, parses and executes it.
 631  */
 632 #define USER_BUF_PAGE 4096
 633 static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
 634                                   size_t len, loff_t *offp)
 635 {
 636         char *tmpbuf;
 637         int ret;
 638
 639         if (len == 0)
 640                 return 0;
 641         if (len > USER_BUF_PAGE - 1) {
 642                 pr_warn("expected <%d bytes into control\n", USER_BUF_PAGE);
 643                 return -E2BIG;
 644         }
 645         tmpbuf = kmalloc(len + 1, GFP_KERNEL);
 646         if (!tmpbuf)
 647                 return -ENOMEM;
 648         if (copy_from_user(tmpbuf, ubuf, len)) {
 649                 kfree(tmpbuf);
 650                 return -EFAULT;
 651         }
 652         tmpbuf[len] = '\0';
 653         vpr_info("read %d bytes from userspace\n", (int)len);
 654
 655         ret = ddebug_exec_queries(tmpbuf);
 656         kfree(tmpbuf);
 657         if (ret < 0)
 658                 return ret;
 659
 660         *offp += len;
 661         return len;
 662 }
 663
 664 /*
 665  * Set the iterator to point to the first _ddebug object
 666  * and return a pointer to that first object.  Returns
 667  * NULL if there are no _ddebugs at all.
 668  */
 669 static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
 670 {
 671         if (list_empty(&ddebug_tables)) {
 672                 iter->table = NULL;
 673                 iter->idx = 0;
 674                 return NULL;
 675         }
 676         iter->table = list_entry(ddebug_tables.next,
 677                                  struct ddebug_table, link);
 678         iter->idx = 0;
 679         return &iter->table->ddebugs[iter->idx];
 680 }
 681
 682 /*
 683  * Advance the iterator to point to the next _ddebug
 684  * object from the one the iterator currently points at,
 685  * and returns a pointer to the new _ddebug.  Returns
 686  * NULL if the iterator has seen all the _ddebugs.
 687  */
 688 static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
 689 {
 690         if (iter->table == NULL)
 691                 return NULL;
 692         if (++iter->idx == iter->table->num_ddebugs) {
 693                 /* iterate to next table */
 694                 iter->idx = 0;
 695                 if (list_is_last(&iter->table->link, &ddebug_tables)) {
 696                         iter->table = NULL;
 697                         return NULL;
 698                 }
 699                 iter->table = list_entry(iter->table->link.next,
 700                                          struct ddebug_table, link);
 701         }
 702         return &iter->table->ddebugs[iter->idx];
 703 }
 704
 705 /*
 706  * Seq_ops start method.  Called at the start of every
 707  * read() call from userspace.  Takes the ddebug_lock and
 708  * seeks the seq_file's iterator to the given position.
 709  */
 710 static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
 711 {
 712         struct ddebug_iter *iter = m->private;
 713         struct _ddebug *dp;
 714         int n = *pos;
 715
 716         vpr_info("called m=%p *pos=%lld\n", m, (unsigned long long)*pos);
 717
 718         mutex_lock(&ddebug_lock);
 719
 720         if (!n)
 721                 return SEQ_START_TOKEN;
 722         if (n < 0)
 723                 return NULL;
 724         dp = ddebug_iter_first(iter);
 725         while (dp != NULL && --n > 0)
 726                 dp = ddebug_iter_next(iter);
 727         return dp;
 728 }
 729
 730 /*
 731  * Seq_ops next method.  Called several times within a read()
 732  * call from userspace, with ddebug_lock held.  Walks to the
 733  * next _ddebug object with a special case for the header line.
 734  */
 735 static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
 736 {
 737         struct ddebug_iter *iter = m->private;
 738         struct _ddebug *dp;
 739
 740         vpr_info("called m=%p p=%p *pos=%lld\n",
 741                 m, p, (unsigned long long)*pos);
 742
 743         if (p == SEQ_START_TOKEN)
 744                 dp = ddebug_iter_first(iter);
 745         else
 746                 dp = ddebug_iter_next(iter);
 747         ++*pos;
 748         return dp;
 749 }
 750
 751 /*
 752  * Seq_ops show method.  Called several times within a read()
 753  * call from userspace, with ddebug_lock held.  Formats the
 754  * current _ddebug as a single human-readable line, with a
 755  * special case for the header line.
 756  */
 757 static int ddebug_proc_show(struct seq_file *m, void *p)
 758 {
 759         struct ddebug_iter *iter = m->private;
 760         struct _ddebug *dp = p;
 761         char flagsbuf[10];
 762
 763         vpr_info("called m=%p p=%p\n", m, p);
 764
 765         if (p == SEQ_START_TOKEN) {
 766                 seq_puts(m,
 767                         "# filename:lineno [module]function flags format\n");
 768                 return 0;
 769         }
 770
 771         seq_printf(m, "%s:%u [%s]%s =%s \"",
 772                 trim_prefix(dp->filename), dp->lineno,
 773                 iter->table->mod_name, dp->function,
 774                 ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
 775         seq_escape(m, dp->format, "\t\r\n\"");
 776         seq_puts(m, "\"\n");
 777
 778         return 0;
 779 }
 780
 781 /*
 782  * Seq_ops stop method.  Called at the end of each read()
 783  * call from userspace.  Drops ddebug_lock.
 784  */
 785 static void ddebug_proc_stop(struct seq_file *m, void *p)
 786 {
 787         vpr_info("called m=%p p=%p\n", m, p);
 788         mutex_unlock(&ddebug_lock);
 789 }
 790
 791 static const struct seq_operations ddebug_proc_seqops = {
 792         .start = ddebug_proc_start,
 793         .next = ddebug_proc_next,
 794         .show = ddebug_proc_show,
 795         .stop = ddebug_proc_stop
 796 };
 797
 798 /*
 799  * File_ops->open method for <debugfs>/dynamic_debug/control.  Does
 800  * the seq_file setup dance, and also creates an iterator to walk the
 801  * _ddebugs.  Note that we create a seq_file always, even for O_WRONLY
 802  * files where it's not needed, as doing so simplifies the ->release
 803  * method.
 804  */
 805 static int ddebug_proc_open(struct inode *inode, struct file *file)
 806 {
 807         struct ddebug_iter *iter;
 808         int err;
 809
 810         vpr_info("called\n");
 811
 812         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
 813         if (iter == NULL)
 814                 return -ENOMEM;
 815
 816         err = seq_open(file, &ddebug_proc_seqops);
 817         if (err) {
 818                 kfree(iter);
 819                 return err;
 820         }
 821         ((struct seq_file *) file->private_data)->private = iter;
 822         return 0;
 823 }
 824
 825 static const struct file_operations ddebug_proc_fops = {
 826         .owner = THIS_MODULE,
 827         .open = ddebug_proc_open,
 828         .read = seq_read,
 829         .llseek = seq_lseek,
 830         .release = seq_release_private,
 831         .write = ddebug_proc_write
 832 };
 833
 834 /*
 835  * Allocate a new ddebug_table for the given module
 836  * and add it to the global list.
 837  */
 838 int ddebug_add_module(struct _ddebug *tab, unsigned int n,
 839                              const char *name)
 840 {
 841         struct ddebug_table *dt;
 842         char *new_name;
 843
 844         dt = kzalloc(sizeof(*dt), GFP_KERNEL);
 845         if (dt == NULL)
 846                 return -ENOMEM;
 847         new_name = kstrdup(name, GFP_KERNEL);
 848         if (new_name == NULL) {
 849                 kfree(dt);
 850                 return -ENOMEM;
 851         }
 852         dt->mod_name = new_name;
 853         dt->num_ddebugs = n;
 854         dt->ddebugs = tab;
 855
 856         mutex_lock(&ddebug_lock);
 857         list_add_tail(&dt->link, &ddebug_tables);
 858         mutex_unlock(&ddebug_lock);
 859
 860         vpr_info("%u debug prints in module %s\n", n, dt->mod_name);
 861         return 0;
 862 }
 863 EXPORT_SYMBOL_GPL(ddebug_add_module);
 864
 865 /* helper for ddebug_dyndbg_(boot|module)_param_cb */
 866 static int ddebug_dyndbg_param_cb(char *param, char *val,
 867                                 const char *modname, int on_err)
 868 {
 869         char *sep;
 870
 871         sep = strchr(param, '.');
 872         if (sep) {
 873                 /* needed only for ddebug_dyndbg_boot_param_cb */
 874                 *sep = '\0';
 875                 modname = param;
 876                 param = sep + 1;
 877         }
 878         if (strcmp(param, "dyndbg"))
 879                 return on_err; /* determined by caller */
 880
 881         ddebug_exec_queries(val ? val : "+p");
 882         return 0; /* query failure shouldnt stop module load */
 883 }
 884
 885 /* handle both dyndbg and $module.dyndbg params at boot */
 886 static int ddebug_dyndbg_boot_param_cb(char *param, char *val,
 887                                 const char *unused)
 888 {
 889         vpr_info("%s=\"%s\"\n", param, val);
 890         return ddebug_dyndbg_param_cb(param, val, NULL, 0);
 891 }
 892
 893 /*
 894  * modprobe foo finds foo.params in boot-args, strips "foo.", and
 895  * passes them to load_module().  This callback gets unknown params,
 896  * processes dyndbg params, rejects others.
 897  */
 898 int ddebug_dyndbg_module_param_cb(char *param, char *val, const char *module)
 899 {
 900         vpr_info("module: %s %s=\"%s\"\n", module, param, val);
 901         return ddebug_dyndbg_param_cb(param, val, module, -ENOENT);
 902 }
 903
 904 static void ddebug_table_free(struct ddebug_table *dt)
 905 {
 906         list_del_init(&dt->link);
 907         kfree(dt->mod_name);
 908         kfree(dt);
 909 }
 910
 911 /*
 912  * Called in response to a module being unloaded.  Removes
 913  * any ddebug_table's which point at the module.
 914  */
 915 int ddebug_remove_module(const char *mod_name)
 916 {
 917         struct ddebug_table *dt, *nextdt;
 918         int ret = -ENOENT;
 919
 920         vpr_info("removing module \"%s\"\n", mod_name);
 921
 922         mutex_lock(&ddebug_lock);
 923         list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
 924                 if (!strcmp(dt->mod_name, mod_name)) {
 925                         ddebug_table_free(dt);
 926                         ret = 0;
 927                 }
 928         }
 929         mutex_unlock(&ddebug_lock);
 930         return ret;
 931 }
 932 EXPORT_SYMBOL_GPL(ddebug_remove_module);
 933
 934 static void ddebug_remove_all_tables(void)
 935 {
 936         mutex_lock(&ddebug_lock);
 937         while (!list_empty(&ddebug_tables)) {
 938                 struct ddebug_table *dt = list_entry(ddebug_tables.next,
 939                                                       struct ddebug_table,
 940                                                       link);
 941                 ddebug_table_free(dt);
 942         }
 943         mutex_unlock(&ddebug_lock);
 944 }
 945
 946 static __initdata int ddebug_init_success;
 947
 948 static int __init dynamic_debug_init_debugfs(void)
 949 {
 950         struct dentry *dir, *file;
 951
 952         if (!ddebug_init_success)
 953                 return -ENODEV;
 954
 955         dir = debugfs_create_dir("dynamic_debug", NULL);
 956         if (!dir)
 957                 return -ENOMEM;
 958         file = debugfs_create_file("control", 0644, dir, NULL,
 959                                         &ddebug_proc_fops);
 960         if (!file) {
 961                 debugfs_remove(dir);
 962                 return -ENOMEM;
 963         }
 964         return 0;
 965 }
 966
 967 static int __init dynamic_debug_init(void)
 968 {
 969         struct _ddebug *iter, *iter_start;
 970         const char *modname = NULL;
 971         char *cmdline;
 972         int ret = 0;
 973         int n = 0, entries = 0, modct = 0;
 974         int verbose_bytes = 0;
 975
 976         if (__start___verbose == __stop___verbose) {
 977                 pr_warn("_ddebug table is empty in a "
 978                         "CONFIG_DYNAMIC_DEBUG build");
 979                 return 1;
 980         }
 981         iter = __start___verbose;
 982         modname = iter->modname;
 983         iter_start = iter;
 984         for (; iter < __stop___verbose; iter++) {
 985                 entries++;
 986                 verbose_bytes += strlen(iter->modname) + strlen(iter->function)
 987                         + strlen(iter->filename) + strlen(iter->format);
 988
 989                 if (strcmp(modname, iter->modname)) {
 990                         modct++;
 991                         ret = ddebug_add_module(iter_start, n, modname);
 992                         if (ret)
 993                                 goto out_err;
 994                         n = 0;
 995                         modname = iter->modname;
 996                         iter_start = iter;
 997                 }
 998                 n++;
 999         }
1000         ret = ddebug_add_module(iter_start, n, modname);
1001         if (ret)
1002                 goto out_err;
1003
1004         ddebug_init_success = 1;
1005         vpr_info("%d modules, %d entries and %d bytes in ddebug tables,"
1006                 " %d bytes in (readonly) verbose section\n",
1007                 modct, entries, (int)( modct * sizeof(struct ddebug_table)),
1008                 verbose_bytes + (int)(__stop___verbose - __start___verbose));
1009
1010         /* apply ddebug_query boot param, dont unload tables on err */
1011         if (ddebug_setup_string[0] != '\0') {
1012                 pr_warn("ddebug_query param name is deprecated,"
1013                         " change it to dyndbg\n");
1014                 ret = ddebug_exec_queries(ddebug_setup_string);
1015                 if (ret < 0)
1016                         pr_warn("Invalid ddebug boot param %s",
1017                                 ddebug_setup_string);
1018                 else
1019                         pr_info("%d changes by ddebug_query\n", ret);
1020         }
1021         /* now that ddebug tables are loaded, process all boot args
1022          * again to find and activate queries given in dyndbg params.
1023          * While this has already been done for known boot params, it
1024          * ignored the unknown ones (dyndbg in particular).  Reusing
1025          * parse_args avoids ad-hoc parsing.  This will also attempt
1026          * to activate queries for not-yet-loaded modules, which is
1027          * slightly noisy if verbose, but harmless.
1028          */
1029         cmdline = kstrdup(saved_command_line, GFP_KERNEL);
1030         parse_args("dyndbg params", cmdline, NULL,
1031                    0, 0, 0, &ddebug_dyndbg_boot_param_cb);
1032         kfree(cmdline);
1033         return 0;
1034
1035 out_err:
1036         ddebug_remove_all_tables();
1037         return 0;
1038 }
1039 /* Allow early initialization for boot messages via boot param */
1040 arch_initcall(dynamic_debug_init);
1041
1042 /* Debugfs setup must be done later */
1043 module_init(dynamic_debug_init_debugfs);