kernel/kallsyms.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
   4  *
   5  * Rewritten and vastly simplified by Rusty Russell for in-kernel
   6  * module loader:
   7  *   Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
   8  *
   9  * ChangeLog:
  10  *
  11  * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
  12  *      Changed the compression method from stem compression to "table lookup"
  13  *      compression (see scripts/kallsyms.c for a more complete description)
  14  */
  15 #include <linux/kallsyms.h>
  16 #include <linux/init.h>
  17 #include <linux/seq_file.h>
  18 #include <linux/fs.h>
  19 #include <linux/kdb.h>
  20 #include <linux/err.h>
  21 #include <linux/proc_fs.h>
  22 #include <linux/sched.h>        /* for cond_resched */
  23 #include <linux/ctype.h>
  24 #include <linux/slab.h>
  25 #include <linux/filter.h>
  26 #include <linux/ftrace.h>
  27 #include <linux/compiler.h>
  28
  29 /*
  30  * These will be re-linked against their real values
  31  * during the second link stage.
  32  */
  33 extern const unsigned long kallsyms_addresses[] __weak;
  34 extern const int kallsyms_offsets[] __weak;
  35 extern const u8 kallsyms_names[] __weak;
  36
  37 /*
  38  * Tell the compiler that the count isn't in the small data section if the arch
  39  * has one (eg: FRV).
  40  */
  41 extern const unsigned int kallsyms_num_syms
  42 __attribute__((weak, section(".rodata")));
  43
  44 extern const unsigned long kallsyms_relative_base
  45 __attribute__((weak, section(".rodata")));
  46
  47 extern const char kallsyms_token_table[] __weak;
  48 extern const u16 kallsyms_token_index[] __weak;
  49
  50 extern const unsigned int kallsyms_markers[] __weak;
  51
  52 /*
  53  * Expand a compressed symbol data into the resulting uncompressed string,
  54  * if uncompressed string is too long (>= maxlen), it will be truncated,
  55  * given the offset to where the symbol is in the compressed stream.
  56  */
  57 static unsigned int kallsyms_expand_symbol(unsigned int off,
  58                                            char *result, size_t maxlen)
  59 {
  60         int len, skipped_first = 0;
  61         const char *tptr;
  62         const u8 *data;
  63
  64         /* Get the compressed symbol length from the first symbol byte. */
  65         data = &kallsyms_names[off];
  66         len = *data;
  67         data++;
  68
  69         /*
  70          * Update the offset to return the offset for the next symbol on
  71          * the compressed stream.
  72          */
  73         off += len + 1;
  74
  75         /*
  76          * For every byte on the compressed symbol data, copy the table
  77          * entry for that byte.
  78          */
  79         while (len) {
  80                 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
  81                 data++;
  82                 len--;
  83
  84                 while (*tptr) {
  85                         if (skipped_first) {
  86                                 if (maxlen <= 1)
  87                                         goto tail;
  88                                 *result = *tptr;
  89                                 result++;
  90                                 maxlen--;
  91                         } else
  92                                 skipped_first = 1;
  93                         tptr++;
  94                 }
  95         }
  96
  97 tail:
  98         if (maxlen)
  99                 *result = '\0';
 100
 101         /* Return to offset to the next symbol. */
 102         return off;
 103 }
 104
 105 /*
 106  * Get symbol type information. This is encoded as a single char at the
 107  * beginning of the symbol name.
 108  */
 109 static char kallsyms_get_symbol_type(unsigned int off)
 110 {
 111         /*
 112          * Get just the first code, look it up in the token table,
 113          * and return the first char from this token.
 114          */
 115         return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
 116 }
 117
 118
 119 /*
 120  * Find the offset on the compressed stream given and index in the
 121  * kallsyms array.
 122  */
 123 static unsigned int get_symbol_offset(unsigned long pos)
 124 {
 125         const u8 *name;
 126         int i;
 127
 128         /*
 129          * Use the closest marker we have. We have markers every 256 positions,
 130          * so that should be close enough.
 131          */
 132         name = &kallsyms_names[kallsyms_markers[pos >> 8]];
 133
 134         /*
 135          * Sequentially scan all the symbols up to the point we're searching
 136          * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
 137          * so we just need to add the len to the current pointer for every
 138          * symbol we wish to skip.
 139          */
 140         for (i = 0; i < (pos & 0xFF); i++)
 141                 name = name + (*name) + 1;
 142
 143         return name - kallsyms_names;
 144 }
 145
 146 static unsigned long kallsyms_sym_address(int idx)
 147 {
 148         if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
 149                 return kallsyms_addresses[idx];
 150
 151         /* values are unsigned offsets if --absolute-percpu is not in effect */
 152         if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
 153                 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
 154
 155         /* ...otherwise, positive offsets are absolute values */
 156         if (kallsyms_offsets[idx] >= 0)
 157                 return kallsyms_offsets[idx];
 158
 159         /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
 160         return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
 161 }
 162
 163 /* Lookup the address for this symbol. Returns 0 if not found. */
 164 unsigned long kallsyms_lookup_name(const char *name)
 165 {
 166         char namebuf[KSYM_NAME_LEN];
 167         unsigned long i;
 168         unsigned int off;
 169
 170         for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
 171                 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
 172
 173                 if (strcmp(namebuf, name) == 0)
 174                         return kallsyms_sym_address(i);
 175         }
 176         return module_kallsyms_lookup_name(name);
 177 }
 178 EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
 179
 180 int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
 181                                       unsigned long),
 182                             void *data)
 183 {
 184         char namebuf[KSYM_NAME_LEN];
 185         unsigned long i;
 186         unsigned int off;
 187         int ret;
 188
 189         for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
 190                 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
 191                 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
 192                 if (ret != 0)
 193                         return ret;
 194         }
 195         return module_kallsyms_on_each_symbol(fn, data);
 196 }
 197 EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
 198
 199 static unsigned long get_symbol_pos(unsigned long addr,
 200                                     unsigned long *symbolsize,
 201                                     unsigned long *offset)
 202 {
 203         unsigned long symbol_start = 0, symbol_end = 0;
 204         unsigned long i, low, high, mid;
 205
 206         /* This kernel should never had been booted. */
 207         if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
 208                 BUG_ON(!kallsyms_addresses);
 209         else
 210                 BUG_ON(!kallsyms_offsets);
 211
 212         /* Do a binary search on the sorted kallsyms_addresses array. */
 213         low = 0;
 214         high = kallsyms_num_syms;
 215
 216         while (high - low > 1) {
 217                 mid = low + (high - low) / 2;
 218                 if (kallsyms_sym_address(mid) <= addr)
 219                         low = mid;
 220                 else
 221                         high = mid;
 222         }
 223
 224         /*
 225          * Search for the first aliased symbol. Aliased
 226          * symbols are symbols with the same address.
 227          */
 228         while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
 229                 --low;
 230
 231         symbol_start = kallsyms_sym_address(low);
 232
 233         /* Search for next non-aliased symbol. */
 234         for (i = low + 1; i < kallsyms_num_syms; i++) {
 235                 if (kallsyms_sym_address(i) > symbol_start) {
 236                         symbol_end = kallsyms_sym_address(i);
 237                         break;
 238                 }
 239         }
 240
 241         /* If we found no next symbol, we use the end of the section. */
 242         if (!symbol_end) {
 243                 if (is_kernel_inittext(addr))
 244                         symbol_end = (unsigned long)_einittext;
 245                 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
 246                         symbol_end = (unsigned long)_end;
 247                 else
 248                         symbol_end = (unsigned long)_etext;
 249         }
 250
 251         if (symbolsize)
 252                 *symbolsize = symbol_end - symbol_start;
 253         if (offset)
 254                 *offset = addr - symbol_start;
 255
 256         return low;
 257 }
 258
 259 /*
 260  * Lookup an address but don't bother to find any names.
 261  */
 262 int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
 263                                 unsigned long *offset)
 264 {
 265         char namebuf[KSYM_NAME_LEN];
 266
 267         if (is_ksym_addr(addr)) {
 268                 get_symbol_pos(addr, symbolsize, offset);
 269                 return 1;
 270         }
 271         return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) ||
 272                !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
 273 }
 274
 275 /*
 276  * Lookup an address
 277  * - modname is set to NULL if it's in the kernel.
 278  * - We guarantee that the returned name is valid until we reschedule even if.
 279  *   It resides in a module.
 280  * - We also guarantee that modname will be valid until rescheduled.
 281  */
 282 const char *kallsyms_lookup(unsigned long addr,
 283                             unsigned long *symbolsize,
 284                             unsigned long *offset,
 285                             char **modname, char *namebuf)
 286 {
 287         const char *ret;
 288
 289         namebuf[KSYM_NAME_LEN - 1] = 0;
 290         namebuf[0] = 0;
 291
 292         if (is_ksym_addr(addr)) {
 293                 unsigned long pos;
 294
 295                 pos = get_symbol_pos(addr, symbolsize, offset);
 296                 /* Grab name */
 297                 kallsyms_expand_symbol(get_symbol_offset(pos),
 298                                        namebuf, KSYM_NAME_LEN);
 299                 if (modname)
 300                         *modname = NULL;
 301                 return namebuf;
 302         }
 303
 304         /* See if it's in a module or a BPF JITed image. */
 305         ret = module_address_lookup(addr, symbolsize, offset,
 306                                     modname, namebuf);
 307         if (!ret)
 308                 ret = bpf_address_lookup(addr, symbolsize,
 309                                          offset, modname, namebuf);
 310
 311         if (!ret)
 312                 ret = ftrace_mod_address_lookup(addr, symbolsize,
 313                                                 offset, modname, namebuf);
 314         return ret;
 315 }
 316
 317 int lookup_symbol_name(unsigned long addr, char *symname)
 318 {
 319         symname[0] = '\0';
 320         symname[KSYM_NAME_LEN - 1] = '\0';
 321
 322         if (is_ksym_addr(addr)) {
 323                 unsigned long pos;
 324
 325                 pos = get_symbol_pos(addr, NULL, NULL);
 326                 /* Grab name */
 327                 kallsyms_expand_symbol(get_symbol_offset(pos),
 328                                        symname, KSYM_NAME_LEN);
 329                 return 0;
 330         }
 331         /* See if it's in a module. */
 332         return lookup_module_symbol_name(addr, symname);
 333 }
 334
 335 int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
 336                         unsigned long *offset, char *modname, char *name)
 337 {
 338         name[0] = '\0';
 339         name[KSYM_NAME_LEN - 1] = '\0';
 340
 341         if (is_ksym_addr(addr)) {
 342                 unsigned long pos;
 343
 344                 pos = get_symbol_pos(addr, size, offset);
 345                 /* Grab name */
 346                 kallsyms_expand_symbol(get_symbol_offset(pos),
 347                                        name, KSYM_NAME_LEN);
 348                 modname[0] = '\0';
 349                 return 0;
 350         }
 351         /* See if it's in a module. */
 352         return lookup_module_symbol_attrs(addr, size, offset, modname, name);
 353 }
 354
 355 /* Look up a kernel symbol and return it in a text buffer. */
 356 static int __sprint_symbol(char *buffer, unsigned long address,
 357                            int symbol_offset, int add_offset)
 358 {
 359         char *modname;
 360         const char *name;
 361         unsigned long offset, size;
 362         int len;
 363
 364         address += symbol_offset;
 365         name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
 366         if (!name)
 367                 return sprintf(buffer, "0x%lx", address - symbol_offset);
 368
 369         if (name != buffer)
 370                 strcpy(buffer, name);
 371         len = strlen(buffer);
 372         offset -= symbol_offset;
 373
 374         if (add_offset)
 375                 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
 376
 377         if (modname)
 378                 len += sprintf(buffer + len, " [%s]", modname);
 379
 380         return len;
 381 }
 382
 383 /**
 384  * sprint_symbol - Look up a kernel symbol and return it in a text buffer
 385  * @buffer: buffer to be stored
 386  * @address: address to lookup
 387  *
 388  * This function looks up a kernel symbol with @address and stores its name,
 389  * offset, size and module name to @buffer if possible. If no symbol was found,
 390  * just saves its @address as is.
 391  *
 392  * This function returns the number of bytes stored in @buffer.
 393  */
 394 int sprint_symbol(char *buffer, unsigned long address)
 395 {
 396         return __sprint_symbol(buffer, address, 0, 1);
 397 }
 398 EXPORT_SYMBOL_GPL(sprint_symbol);
 399
 400 /**
 401  * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
 402  * @buffer: buffer to be stored
 403  * @address: address to lookup
 404  *
 405  * This function looks up a kernel symbol with @address and stores its name
 406  * and module name to @buffer if possible. If no symbol was found, just saves
 407  * its @address as is.
 408  *
 409  * This function returns the number of bytes stored in @buffer.
 410  */
 411 int sprint_symbol_no_offset(char *buffer, unsigned long address)
 412 {
 413         return __sprint_symbol(buffer, address, 0, 0);
 414 }
 415 EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
 416
 417 /**
 418  * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
 419  * @buffer: buffer to be stored
 420  * @address: address to lookup
 421  *
 422  * This function is for stack backtrace and does the same thing as
 423  * sprint_symbol() but with modified/decreased @address. If there is a
 424  * tail-call to the function marked "noreturn", gcc optimized out code after
 425  * the call so that the stack-saved return address could point outside of the
 426  * caller. This function ensures that kallsyms will find the original caller
 427  * by decreasing @address.
 428  *
 429  * This function returns the number of bytes stored in @buffer.
 430  */
 431 int sprint_backtrace(char *buffer, unsigned long address)
 432 {
 433         return __sprint_symbol(buffer, address, -1, 1);
 434 }
 435
 436 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
 437 struct kallsym_iter {
 438         loff_t pos;
 439         loff_t pos_arch_end;
 440         loff_t pos_mod_end;
 441         loff_t pos_ftrace_mod_end;
 442         unsigned long value;
 443         unsigned int nameoff; /* If iterating in core kernel symbols. */
 444         char type;
 445         char name[KSYM_NAME_LEN];
 446         char module_name[MODULE_NAME_LEN];
 447         int exported;
 448         int show_value;
 449 };
 450
 451 int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
 452                             char *type, char *name)
 453 {
 454         return -EINVAL;
 455 }
 456
 457 static int get_ksymbol_arch(struct kallsym_iter *iter)
 458 {
 459         int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,
 460                                    &iter->value, &iter->type,
 461                                    iter->name);
 462
 463         if (ret < 0) {
 464                 iter->pos_arch_end = iter->pos;
 465                 return 0;
 466         }
 467
 468         return 1;
 469 }
 470
 471 static int get_ksymbol_mod(struct kallsym_iter *iter)
 472 {
 473         int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,
 474                                      &iter->value, &iter->type,
 475                                      iter->name, iter->module_name,
 476                                      &iter->exported);
 477         if (ret < 0) {
 478                 iter->pos_mod_end = iter->pos;
 479                 return 0;
 480         }
 481
 482         return 1;
 483 }
 484
 485 static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
 486 {
 487         int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
 488                                          &iter->value, &iter->type,
 489                                          iter->name, iter->module_name,
 490                                          &iter->exported);
 491         if (ret < 0) {
 492                 iter->pos_ftrace_mod_end = iter->pos;
 493                 return 0;
 494         }
 495
 496         return 1;
 497 }
 498
 499 static int get_ksymbol_bpf(struct kallsym_iter *iter)
 500 {
 501         strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
 502         iter->exported = 0;
 503         return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
 504                                &iter->value, &iter->type,
 505                                iter->name) < 0 ? 0 : 1;
 506 }
 507
 508 /* Returns space to next name. */
 509 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
 510 {
 511         unsigned off = iter->nameoff;
 512
 513         iter->module_name[0] = '\0';
 514         iter->value = kallsyms_sym_address(iter->pos);
 515
 516         iter->type = kallsyms_get_symbol_type(off);
 517
 518         off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
 519
 520         return off - iter->nameoff;
 521 }
 522
 523 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
 524 {
 525         iter->name[0] = '\0';
 526         iter->nameoff = get_symbol_offset(new_pos);
 527         iter->pos = new_pos;
 528         if (new_pos == 0) {
 529                 iter->pos_arch_end = 0;
 530                 iter->pos_mod_end = 0;
 531                 iter->pos_ftrace_mod_end = 0;
 532         }
 533 }
 534
 535 /*
 536  * The end position (last + 1) of each additional kallsyms section is recorded
 537  * in iter->pos_..._end as each section is added, and so can be used to
 538  * determine which get_ksymbol_...() function to call next.
 539  */
 540 static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
 541 {
 542         iter->pos = pos;
 543
 544         if ((!iter->pos_arch_end || iter->pos_arch_end > pos) &&
 545             get_ksymbol_arch(iter))
 546                 return 1;
 547
 548         if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
 549             get_ksymbol_mod(iter))
 550                 return 1;
 551
 552         if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
 553             get_ksymbol_ftrace_mod(iter))
 554                 return 1;
 555
 556         return get_ksymbol_bpf(iter);
 557 }
 558
 559 /* Returns false if pos at or past end of file. */
 560 static int update_iter(struct kallsym_iter *iter, loff_t pos)
 561 {
 562         /* Module symbols can be accessed randomly. */
 563         if (pos >= kallsyms_num_syms)
 564                 return update_iter_mod(iter, pos);
 565
 566         /* If we're not on the desired position, reset to new position. */
 567         if (pos != iter->pos)
 568                 reset_iter(iter, pos);
 569
 570         iter->nameoff += get_ksymbol_core(iter);
 571         iter->pos++;
 572
 573         return 1;
 574 }
 575
 576 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
 577 {
 578         (*pos)++;
 579
 580         if (!update_iter(m->private, *pos))
 581                 return NULL;
 582         return p;
 583 }
 584
 585 static void *s_start(struct seq_file *m, loff_t *pos)
 586 {
 587         if (!update_iter(m->private, *pos))
 588                 return NULL;
 589         return m->private;
 590 }
 591
 592 static void s_stop(struct seq_file *m, void *p)
 593 {
 594 }
 595
 596 static int s_show(struct seq_file *m, void *p)
 597 {
 598         void *value;
 599         struct kallsym_iter *iter = m->private;
 600
 601         /* Some debugging symbols have no name.  Ignore them. */
 602         if (!iter->name[0])
 603                 return 0;
 604
 605         value = iter->show_value ? (void *)iter->value : NULL;
 606
 607         if (iter->module_name[0]) {
 608                 char type;
 609
 610                 /*
 611                  * Label it "global" if it is exported,
 612                  * "local" if not exported.
 613                  */
 614                 type = iter->exported ? toupper(iter->type) :
 615                                         tolower(iter->type);
 616                 seq_printf(m, "%px %c %s\t[%s]\n", value,
 617                            type, iter->name, iter->module_name);
 618         } else
 619                 seq_printf(m, "%px %c %s\n", value,
 620                            iter->type, iter->name);
 621         return 0;
 622 }
 623
 624 static const struct seq_operations kallsyms_op = {
 625         .start = s_start,
 626         .next = s_next,
 627         .stop = s_stop,
 628         .show = s_show
 629 };
 630
 631 static inline int kallsyms_for_perf(void)
 632 {
 633 #ifdef CONFIG_PERF_EVENTS
 634         extern int sysctl_perf_event_paranoid;
 635         if (sysctl_perf_event_paranoid <= 1)
 636                 return 1;
 637 #endif
 638         return 0;
 639 }
 640
 641 /*
 642  * We show kallsyms information even to normal users if we've enabled
 643  * kernel profiling and are explicitly not paranoid (so kptr_restrict
 644  * is clear, and sysctl_perf_event_paranoid isn't set).
 645  *
 646  * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
 647  * block even that).
 648  */
 649 int kallsyms_show_value(void)
 650 {
 651         switch (kptr_restrict) {
 652         case 0:
 653                 if (kallsyms_for_perf())
 654                         return 1;
 655         /* fallthrough */
 656         case 1:
 657                 if (has_capability_noaudit(current, CAP_SYSLOG))
 658                         return 1;
 659         /* fallthrough */
 660         default:
 661                 return 0;
 662         }
 663 }
 664
 665 static int kallsyms_open(struct inode *inode, struct file *file)
 666 {
 667         /*
 668          * We keep iterator in m->private, since normal case is to
 669          * s_start from where we left off, so we avoid doing
 670          * using get_symbol_offset for every symbol.
 671          */
 672         struct kallsym_iter *iter;
 673         iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
 674         if (!iter)
 675                 return -ENOMEM;
 676         reset_iter(iter, 0);
 677
 678         iter->show_value = kallsyms_show_value();
 679         return 0;
 680 }
 681
 682 #ifdef  CONFIG_KGDB_KDB
 683 const char *kdb_walk_kallsyms(loff_t *pos)
 684 {
 685         static struct kallsym_iter kdb_walk_kallsyms_iter;
 686         if (*pos == 0) {
 687                 memset(&kdb_walk_kallsyms_iter, 0,
 688                        sizeof(kdb_walk_kallsyms_iter));
 689                 reset_iter(&kdb_walk_kallsyms_iter, 0);
 690         }
 691         while (1) {
 692                 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
 693                         return NULL;
 694                 ++*pos;
 695                 /* Some debugging symbols have no name.  Ignore them. */
 696                 if (kdb_walk_kallsyms_iter.name[0])
 697                         return kdb_walk_kallsyms_iter.name;
 698         }
 699 }
 700 #endif  /* CONFIG_KGDB_KDB */
 701
 702 static const struct proc_ops kallsyms_proc_ops = {
 703         .proc_open      = kallsyms_open,
 704         .proc_read      = seq_read,
 705         .proc_lseek     = seq_lseek,
 706         .proc_release   = seq_release_private,
 707 };
 708
 709 static int __init kallsyms_init(void)
 710 {
 711         proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
 712         return 0;
 713 }
 714 device_initcall(kallsyms_init);