| 1 | /* |
| 2 | * kallsyms.c: in-kernel printing of symbolic oopses and stack traces. |
| 3 | * |
| 4 | * Rewritten and vastly simplified by Rusty Russell for in-kernel |
| 5 | * module loader: |
| 6 | * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation |
| 7 | * |
| 8 | * ChangeLog: |
| 9 | * |
| 10 | * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com> |
| 11 | * Changed the compression method from stem compression to "table lookup" |
| 12 | * compression (see scripts/kallsyms.c for a more complete description) |
| 13 | */ |
| 14 | #include <linux/kallsyms.h> |
| 15 | #include <linux/module.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/mm.h> |
| 24 | #include <linux/ctype.h> |
| 25 | #include <linux/slab.h> |
| 26 | |
| 27 | #include <asm/sections.h> |
| 28 | |
| 29 | #ifdef CONFIG_KALLSYMS_ALL |
| 30 | #define all_var 1 |
| 31 | #else |
| 32 | #define all_var 0 |
| 33 | #endif |
| 34 | |
| 35 | /* |
| 36 | * These will be re-linked against their real values |
| 37 | * during the second link stage. |
| 38 | */ |
| 39 | extern const unsigned long kallsyms_addresses[] __attribute__((weak)); |
| 40 | extern const u8 kallsyms_names[] __attribute__((weak)); |
| 41 | |
| 42 | /* |
| 43 | * Tell the compiler that the count isn't in the small data section if the arch |
| 44 | * has one (eg: FRV). |
| 45 | */ |
| 46 | extern const unsigned long kallsyms_num_syms |
| 47 | __attribute__((weak, section(".rodata"))); |
| 48 | |
| 49 | extern const u8 kallsyms_token_table[] __attribute__((weak)); |
| 50 | extern const u16 kallsyms_token_index[] __attribute__((weak)); |
| 51 | |
| 52 | extern const unsigned long kallsyms_markers[] __attribute__((weak)); |
| 53 | |
| 54 | static inline int is_kernel_inittext(unsigned long addr) |
| 55 | { |
| 56 | if (addr >= (unsigned long)_sinittext |
| 57 | && addr <= (unsigned long)_einittext) |
| 58 | return 1; |
| 59 | return 0; |
| 60 | } |
| 61 | |
| 62 | static inline int is_kernel_text(unsigned long addr) |
| 63 | { |
| 64 | if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) || |
| 65 | arch_is_kernel_text(addr)) |
| 66 | return 1; |
| 67 | return in_gate_area_no_mm(addr); |
| 68 | } |
| 69 | |
| 70 | static inline int is_kernel(unsigned long addr) |
| 71 | { |
| 72 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) |
| 73 | return 1; |
| 74 | return in_gate_area_no_mm(addr); |
| 75 | } |
| 76 | |
| 77 | static int is_ksym_addr(unsigned long addr) |
| 78 | { |
| 79 | if (all_var) |
| 80 | return is_kernel(addr); |
| 81 | |
| 82 | return is_kernel_text(addr) || is_kernel_inittext(addr); |
| 83 | } |
| 84 | |
| 85 | /* |
| 86 | * Expand a compressed symbol data into the resulting uncompressed string, |
| 87 | * given the offset to where the symbol is in the compressed stream. |
| 88 | */ |
| 89 | static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) |
| 90 | { |
| 91 | int len, skipped_first = 0; |
| 92 | const u8 *tptr, *data; |
| 93 | |
| 94 | /* Get the compressed symbol length from the first symbol byte. */ |
| 95 | data = &kallsyms_names[off]; |
| 96 | len = *data; |
| 97 | data++; |
| 98 | |
| 99 | /* |
| 100 | * Update the offset to return the offset for the next symbol on |
| 101 | * the compressed stream. |
| 102 | */ |
| 103 | off += len + 1; |
| 104 | |
| 105 | /* |
| 106 | * For every byte on the compressed symbol data, copy the table |
| 107 | * entry for that byte. |
| 108 | */ |
| 109 | while (len) { |
| 110 | tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; |
| 111 | data++; |
| 112 | len--; |
| 113 | |
| 114 | while (*tptr) { |
| 115 | if (skipped_first) { |
| 116 | *result = *tptr; |
| 117 | result++; |
| 118 | } else |
| 119 | skipped_first = 1; |
| 120 | tptr++; |
| 121 | } |
| 122 | } |
| 123 | |
| 124 | *result = '\0'; |
| 125 | |
| 126 | /* Return to offset to the next symbol. */ |
| 127 | return off; |
| 128 | } |
| 129 | |
| 130 | /* |
| 131 | * Get symbol type information. This is encoded as a single char at the |
| 132 | * beginning of the symbol name. |
| 133 | */ |
| 134 | static char kallsyms_get_symbol_type(unsigned int off) |
| 135 | { |
| 136 | /* |
| 137 | * Get just the first code, look it up in the token table, |
| 138 | * and return the first char from this token. |
| 139 | */ |
| 140 | return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; |
| 141 | } |
| 142 | |
| 143 | |
| 144 | /* |
| 145 | * Find the offset on the compressed stream given and index in the |
| 146 | * kallsyms array. |
| 147 | */ |
| 148 | static unsigned int get_symbol_offset(unsigned long pos) |
| 149 | { |
| 150 | const u8 *name; |
| 151 | int i; |
| 152 | |
| 153 | /* |
| 154 | * Use the closest marker we have. We have markers every 256 positions, |
| 155 | * so that should be close enough. |
| 156 | */ |
| 157 | name = &kallsyms_names[kallsyms_markers[pos >> 8]]; |
| 158 | |
| 159 | /* |
| 160 | * Sequentially scan all the symbols up to the point we're searching |
| 161 | * for. Every symbol is stored in a [<len>][<len> bytes of data] format, |
| 162 | * so we just need to add the len to the current pointer for every |
| 163 | * symbol we wish to skip. |
| 164 | */ |
| 165 | for (i = 0; i < (pos & 0xFF); i++) |
| 166 | name = name + (*name) + 1; |
| 167 | |
| 168 | return name - kallsyms_names; |
| 169 | } |
| 170 | |
| 171 | /* Lookup the address for this symbol. Returns 0 if not found. */ |
| 172 | unsigned long kallsyms_lookup_name(const char *name) |
| 173 | { |
| 174 | char namebuf[KSYM_NAME_LEN]; |
| 175 | unsigned long i; |
| 176 | unsigned int off; |
| 177 | |
| 178 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
| 179 | off = kallsyms_expand_symbol(off, namebuf); |
| 180 | |
| 181 | if (strcmp(namebuf, name) == 0) |
| 182 | return kallsyms_addresses[i]; |
| 183 | } |
| 184 | return module_kallsyms_lookup_name(name); |
| 185 | } |
| 186 | EXPORT_SYMBOL_GPL(kallsyms_lookup_name); |
| 187 | |
| 188 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, |
| 189 | unsigned long), |
| 190 | void *data) |
| 191 | { |
| 192 | char namebuf[KSYM_NAME_LEN]; |
| 193 | unsigned long i; |
| 194 | unsigned int off; |
| 195 | int ret; |
| 196 | |
| 197 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
| 198 | off = kallsyms_expand_symbol(off, namebuf); |
| 199 | ret = fn(data, namebuf, NULL, kallsyms_addresses[i]); |
| 200 | if (ret != 0) |
| 201 | return ret; |
| 202 | } |
| 203 | return module_kallsyms_on_each_symbol(fn, data); |
| 204 | } |
| 205 | EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol); |
| 206 | |
| 207 | static unsigned long get_symbol_pos(unsigned long addr, |
| 208 | unsigned long *symbolsize, |
| 209 | unsigned long *offset) |
| 210 | { |
| 211 | unsigned long symbol_start = 0, symbol_end = 0; |
| 212 | unsigned long i, low, high, mid; |
| 213 | |
| 214 | /* This kernel should never had been booted. */ |
| 215 | BUG_ON(!kallsyms_addresses); |
| 216 | |
| 217 | /* Do a binary search on the sorted kallsyms_addresses array. */ |
| 218 | low = 0; |
| 219 | high = kallsyms_num_syms; |
| 220 | |
| 221 | while (high - low > 1) { |
| 222 | mid = low + (high - low) / 2; |
| 223 | if (kallsyms_addresses[mid] <= addr) |
| 224 | low = mid; |
| 225 | else |
| 226 | high = mid; |
| 227 | } |
| 228 | |
| 229 | /* |
| 230 | * Search for the first aliased symbol. Aliased |
| 231 | * symbols are symbols with the same address. |
| 232 | */ |
| 233 | while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low]) |
| 234 | --low; |
| 235 | |
| 236 | symbol_start = kallsyms_addresses[low]; |
| 237 | |
| 238 | /* Search for next non-aliased symbol. */ |
| 239 | for (i = low + 1; i < kallsyms_num_syms; i++) { |
| 240 | if (kallsyms_addresses[i] > symbol_start) { |
| 241 | symbol_end = kallsyms_addresses[i]; |
| 242 | break; |
| 243 | } |
| 244 | } |
| 245 | |
| 246 | /* If we found no next symbol, we use the end of the section. */ |
| 247 | if (!symbol_end) { |
| 248 | if (is_kernel_inittext(addr)) |
| 249 | symbol_end = (unsigned long)_einittext; |
| 250 | else if (all_var) |
| 251 | symbol_end = (unsigned long)_end; |
| 252 | else |
| 253 | symbol_end = (unsigned long)_etext; |
| 254 | } |
| 255 | |
| 256 | if (symbolsize) |
| 257 | *symbolsize = symbol_end - symbol_start; |
| 258 | if (offset) |
| 259 | *offset = addr - symbol_start; |
| 260 | |
| 261 | return low; |
| 262 | } |
| 263 | |
| 264 | /* |
| 265 | * Lookup an address but don't bother to find any names. |
| 266 | */ |
| 267 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, |
| 268 | unsigned long *offset) |
| 269 | { |
| 270 | char namebuf[KSYM_NAME_LEN]; |
| 271 | if (is_ksym_addr(addr)) |
| 272 | return !!get_symbol_pos(addr, symbolsize, offset); |
| 273 | |
| 274 | return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf); |
| 275 | } |
| 276 | |
| 277 | /* |
| 278 | * Lookup an address |
| 279 | * - modname is set to NULL if it's in the kernel. |
| 280 | * - We guarantee that the returned name is valid until we reschedule even if. |
| 281 | * It resides in a module. |
| 282 | * - We also guarantee that modname will be valid until rescheduled. |
| 283 | */ |
| 284 | const char *kallsyms_lookup(unsigned long addr, |
| 285 | unsigned long *symbolsize, |
| 286 | unsigned long *offset, |
| 287 | char **modname, char *namebuf) |
| 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), namebuf); |
| 298 | if (modname) |
| 299 | *modname = NULL; |
| 300 | return namebuf; |
| 301 | } |
| 302 | |
| 303 | /* See if it's in a module. */ |
| 304 | return module_address_lookup(addr, symbolsize, offset, modname, |
| 305 | namebuf); |
| 306 | } |
| 307 | |
| 308 | int lookup_symbol_name(unsigned long addr, char *symname) |
| 309 | { |
| 310 | symname[0] = '\0'; |
| 311 | symname[KSYM_NAME_LEN - 1] = '\0'; |
| 312 | |
| 313 | if (is_ksym_addr(addr)) { |
| 314 | unsigned long pos; |
| 315 | |
| 316 | pos = get_symbol_pos(addr, NULL, NULL); |
| 317 | /* Grab name */ |
| 318 | kallsyms_expand_symbol(get_symbol_offset(pos), symname); |
| 319 | return 0; |
| 320 | } |
| 321 | /* See if it's in a module. */ |
| 322 | return lookup_module_symbol_name(addr, symname); |
| 323 | } |
| 324 | |
| 325 | int lookup_symbol_attrs(unsigned long addr, unsigned long *size, |
| 326 | unsigned long *offset, char *modname, char *name) |
| 327 | { |
| 328 | name[0] = '\0'; |
| 329 | name[KSYM_NAME_LEN - 1] = '\0'; |
| 330 | |
| 331 | if (is_ksym_addr(addr)) { |
| 332 | unsigned long pos; |
| 333 | |
| 334 | pos = get_symbol_pos(addr, size, offset); |
| 335 | /* Grab name */ |
| 336 | kallsyms_expand_symbol(get_symbol_offset(pos), name); |
| 337 | modname[0] = '\0'; |
| 338 | return 0; |
| 339 | } |
| 340 | /* See if it's in a module. */ |
| 341 | return lookup_module_symbol_attrs(addr, size, offset, modname, name); |
| 342 | } |
| 343 | |
| 344 | /* Look up a kernel symbol and return it in a text buffer. */ |
| 345 | static int __sprint_symbol(char *buffer, unsigned long address, |
| 346 | int symbol_offset) |
| 347 | { |
| 348 | char *modname; |
| 349 | const char *name; |
| 350 | unsigned long offset, size; |
| 351 | int len; |
| 352 | |
| 353 | address += symbol_offset; |
| 354 | name = kallsyms_lookup(address, &size, &offset, &modname, buffer); |
| 355 | if (!name) |
| 356 | return sprintf(buffer, "0x%lx", address); |
| 357 | |
| 358 | if (name != buffer) |
| 359 | strcpy(buffer, name); |
| 360 | len = strlen(buffer); |
| 361 | buffer += len; |
| 362 | offset -= symbol_offset; |
| 363 | |
| 364 | if (modname) |
| 365 | len += sprintf(buffer, "+%#lx/%#lx [%s]", offset, size, modname); |
| 366 | else |
| 367 | len += sprintf(buffer, "+%#lx/%#lx", offset, size); |
| 368 | |
| 369 | return len; |
| 370 | } |
| 371 | |
| 372 | /** |
| 373 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer |
| 374 | * @buffer: buffer to be stored |
| 375 | * @address: address to lookup |
| 376 | * |
| 377 | * This function looks up a kernel symbol with @address and stores its name, |
| 378 | * offset, size and module name to @buffer if possible. If no symbol was found, |
| 379 | * just saves its @address as is. |
| 380 | * |
| 381 | * This function returns the number of bytes stored in @buffer. |
| 382 | */ |
| 383 | int sprint_symbol(char *buffer, unsigned long address) |
| 384 | { |
| 385 | return __sprint_symbol(buffer, address, 0); |
| 386 | } |
| 387 | |
| 388 | EXPORT_SYMBOL_GPL(sprint_symbol); |
| 389 | |
| 390 | /** |
| 391 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer |
| 392 | * @buffer: buffer to be stored |
| 393 | * @address: address to lookup |
| 394 | * |
| 395 | * This function is for stack backtrace and does the same thing as |
| 396 | * sprint_symbol() but with modified/decreased @address. If there is a |
| 397 | * tail-call to the function marked "noreturn", gcc optimized out code after |
| 398 | * the call so that the stack-saved return address could point outside of the |
| 399 | * caller. This function ensures that kallsyms will find the original caller |
| 400 | * by decreasing @address. |
| 401 | * |
| 402 | * This function returns the number of bytes stored in @buffer. |
| 403 | */ |
| 404 | int sprint_backtrace(char *buffer, unsigned long address) |
| 405 | { |
| 406 | return __sprint_symbol(buffer, address, -1); |
| 407 | } |
| 408 | |
| 409 | /* Look up a kernel symbol and print it to the kernel messages. */ |
| 410 | void __print_symbol(const char *fmt, unsigned long address) |
| 411 | { |
| 412 | char buffer[KSYM_SYMBOL_LEN]; |
| 413 | |
| 414 | sprint_symbol(buffer, address); |
| 415 | |
| 416 | printk(fmt, buffer); |
| 417 | } |
| 418 | EXPORT_SYMBOL(__print_symbol); |
| 419 | |
| 420 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ |
| 421 | struct kallsym_iter { |
| 422 | loff_t pos; |
| 423 | unsigned long value; |
| 424 | unsigned int nameoff; /* If iterating in core kernel symbols. */ |
| 425 | char type; |
| 426 | char name[KSYM_NAME_LEN]; |
| 427 | char module_name[MODULE_NAME_LEN]; |
| 428 | int exported; |
| 429 | }; |
| 430 | |
| 431 | static int get_ksymbol_mod(struct kallsym_iter *iter) |
| 432 | { |
| 433 | if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value, |
| 434 | &iter->type, iter->name, iter->module_name, |
| 435 | &iter->exported) < 0) |
| 436 | return 0; |
| 437 | return 1; |
| 438 | } |
| 439 | |
| 440 | /* Returns space to next name. */ |
| 441 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) |
| 442 | { |
| 443 | unsigned off = iter->nameoff; |
| 444 | |
| 445 | iter->module_name[0] = '\0'; |
| 446 | iter->value = kallsyms_addresses[iter->pos]; |
| 447 | |
| 448 | iter->type = kallsyms_get_symbol_type(off); |
| 449 | |
| 450 | off = kallsyms_expand_symbol(off, iter->name); |
| 451 | |
| 452 | return off - iter->nameoff; |
| 453 | } |
| 454 | |
| 455 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) |
| 456 | { |
| 457 | iter->name[0] = '\0'; |
| 458 | iter->nameoff = get_symbol_offset(new_pos); |
| 459 | iter->pos = new_pos; |
| 460 | } |
| 461 | |
| 462 | /* Returns false if pos at or past end of file. */ |
| 463 | static int update_iter(struct kallsym_iter *iter, loff_t pos) |
| 464 | { |
| 465 | /* Module symbols can be accessed randomly. */ |
| 466 | if (pos >= kallsyms_num_syms) { |
| 467 | iter->pos = pos; |
| 468 | return get_ksymbol_mod(iter); |
| 469 | } |
| 470 | |
| 471 | /* If we're not on the desired position, reset to new position. */ |
| 472 | if (pos != iter->pos) |
| 473 | reset_iter(iter, pos); |
| 474 | |
| 475 | iter->nameoff += get_ksymbol_core(iter); |
| 476 | iter->pos++; |
| 477 | |
| 478 | return 1; |
| 479 | } |
| 480 | |
| 481 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) |
| 482 | { |
| 483 | (*pos)++; |
| 484 | |
| 485 | if (!update_iter(m->private, *pos)) |
| 486 | return NULL; |
| 487 | return p; |
| 488 | } |
| 489 | |
| 490 | static void *s_start(struct seq_file *m, loff_t *pos) |
| 491 | { |
| 492 | if (!update_iter(m->private, *pos)) |
| 493 | return NULL; |
| 494 | return m->private; |
| 495 | } |
| 496 | |
| 497 | static void s_stop(struct seq_file *m, void *p) |
| 498 | { |
| 499 | } |
| 500 | |
| 501 | static int s_show(struct seq_file *m, void *p) |
| 502 | { |
| 503 | struct kallsym_iter *iter = m->private; |
| 504 | |
| 505 | /* Some debugging symbols have no name. Ignore them. */ |
| 506 | if (!iter->name[0]) |
| 507 | return 0; |
| 508 | |
| 509 | if (iter->module_name[0]) { |
| 510 | char type; |
| 511 | |
| 512 | /* |
| 513 | * Label it "global" if it is exported, |
| 514 | * "local" if not exported. |
| 515 | */ |
| 516 | type = iter->exported ? toupper(iter->type) : |
| 517 | tolower(iter->type); |
| 518 | seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value, |
| 519 | type, iter->name, iter->module_name); |
| 520 | } else |
| 521 | seq_printf(m, "%pK %c %s\n", (void *)iter->value, |
| 522 | iter->type, iter->name); |
| 523 | return 0; |
| 524 | } |
| 525 | |
| 526 | static const struct seq_operations kallsyms_op = { |
| 527 | .start = s_start, |
| 528 | .next = s_next, |
| 529 | .stop = s_stop, |
| 530 | .show = s_show |
| 531 | }; |
| 532 | |
| 533 | static int kallsyms_open(struct inode *inode, struct file *file) |
| 534 | { |
| 535 | /* |
| 536 | * We keep iterator in m->private, since normal case is to |
| 537 | * s_start from where we left off, so we avoid doing |
| 538 | * using get_symbol_offset for every symbol. |
| 539 | */ |
| 540 | struct kallsym_iter *iter; |
| 541 | int ret; |
| 542 | |
| 543 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); |
| 544 | if (!iter) |
| 545 | return -ENOMEM; |
| 546 | reset_iter(iter, 0); |
| 547 | |
| 548 | ret = seq_open(file, &kallsyms_op); |
| 549 | if (ret == 0) |
| 550 | ((struct seq_file *)file->private_data)->private = iter; |
| 551 | else |
| 552 | kfree(iter); |
| 553 | return ret; |
| 554 | } |
| 555 | |
| 556 | #ifdef CONFIG_KGDB_KDB |
| 557 | const char *kdb_walk_kallsyms(loff_t *pos) |
| 558 | { |
| 559 | static struct kallsym_iter kdb_walk_kallsyms_iter; |
| 560 | if (*pos == 0) { |
| 561 | memset(&kdb_walk_kallsyms_iter, 0, |
| 562 | sizeof(kdb_walk_kallsyms_iter)); |
| 563 | reset_iter(&kdb_walk_kallsyms_iter, 0); |
| 564 | } |
| 565 | while (1) { |
| 566 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) |
| 567 | return NULL; |
| 568 | ++*pos; |
| 569 | /* Some debugging symbols have no name. Ignore them. */ |
| 570 | if (kdb_walk_kallsyms_iter.name[0]) |
| 571 | return kdb_walk_kallsyms_iter.name; |
| 572 | } |
| 573 | } |
| 574 | #endif /* CONFIG_KGDB_KDB */ |
| 575 | |
| 576 | static const struct file_operations kallsyms_operations = { |
| 577 | .open = kallsyms_open, |
| 578 | .read = seq_read, |
| 579 | .llseek = seq_lseek, |
| 580 | .release = seq_release_private, |
| 581 | }; |
| 582 | |
| 583 | static int __init kallsyms_init(void) |
| 584 | { |
| 585 | proc_create("kallsyms", 0444, NULL, &kallsyms_operations); |
| 586 | return 0; |
| 587 | } |
| 588 | device_initcall(kallsyms_init); |