| 1 | |
| 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 <[email protected]> IBM Corporation
|
| 8 | *
|
| 9 | * ChangeLog:
|
| 10 | *
|
| 11 | * (25/Aug/2004) Paulo Marques <[email protected]>
|
| 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>
|
| 23 | #include <linux/ctype.h>
|
| 24 | #include <linux/slab.h>
|
| 25 | #include <linux/filter.h>
|
| 26 | #include <linux/ftrace.h>
|
| 27 | #include <linux/kprobes.h>
|
| 28 | #include <linux/build_bug.h>
|
| 29 | #include <linux/compiler.h>
|
| 30 | #include <linux/module.h>
|
| 31 | #include <linux/kernel.h>
|
| 32 | #include <linux/bsearch.h>
|
| 33 | #include <linux/btf_ids.h>
|
| 34 |
|
| 35 | #include "kallsyms_internal.h"
|
| 36 |
|
| 37 | |
| 38 | * Expand a compressed symbol data into the resulting uncompressed string,
|
| 39 | * if uncompressed string is too long (>= maxlen), it will be truncated,
|
| 40 | * given the offset to where the symbol is in the compressed stream.
|
| 41 |
|
| 42 | static unsigned int kallsyms_expand_symbol(unsigned int off,
|
| 43 | char *result, size_t maxlen)
|
| 44 | {
|
| 45 | int len, skipped_first = 0;
|
| 46 | const char *tptr;
|
| 47 | const u8 *data;
|
| 48 |
|
| 49 |
|
| 50 | data = &kallsyms_names[off];
|
| 51 | len = *data;
|
| 52 | data++;
|
| 53 | off++;
|
| 54 |
|
| 55 |
|
| 56 | if ((len & 0x80) != 0) {
|
| 57 | len = (len & 0x7F) | (*data << 7);
|
| 58 | data++;
|
| 59 | off++;
|
| 60 | }
|
| 61 |
|
| 62 | |
| 63 | * Update the offset to return the offset for the next symbol on
|
| 64 | * the compressed stream.
|
| 65 |
|
| 66 | off += len;
|
| 67 |
|
| 68 | |
| 69 | * For every byte on the compressed symbol data, copy the table
|
| 70 | * entry for that byte.
|
| 71 |
|
| 72 | while (len) {
|
| 73 | tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
|
| 74 | data++;
|
| 75 | len--;
|
| 76 |
|
| 77 | while (*tptr) {
|
| 78 | if (skipped_first) {
|
| 79 | if (maxlen <= 1)
|
| 80 | goto tail;
|
| 81 | *result = *tptr;
|
| 82 | result++;
|
| 83 | maxlen--;
|
| 84 | } else
|
| 85 | skipped_first = 1;
|
| 86 | tptr++;
|
| 87 | }
|
| 88 | }
|
| 89 |
|
| 90 | tail:
|
| 91 | if (maxlen)
|
| 92 | *result = '\0';
|
| 93 |
|
| 94 |
|
| 95 | return off;
|
| 96 | }
|
| 97 |
|
| 98 | |
| 99 | * Get symbol type information. This is encoded as a single char at the
|
| 100 | * beginning of the symbol name.
|
| 101 |
|
| 102 | static char kallsyms_get_symbol_type(unsigned int off)
|
| 103 | {
|
| 104 | |
| 105 | * Get just the first code, look it up in the token table,
|
| 106 | * and return the first char from this token.
|
| 107 |
|
| 108 | return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
|
| 109 | }
|
| 110 |
|
| 111 |
|
| 112 | |
| 113 | * Find the offset on the compressed stream given and index in the
|
| 114 | * kallsyms array.
|
| 115 |
|
| 116 | static unsigned int get_symbol_offset(unsigned long pos)
|
| 117 | {
|
| 118 | const u8 *name;
|
| 119 | int i, len;
|
| 120 |
|
| 121 | |
| 122 | * Use the closest marker we have. We have markers every 256 positions,
|
| 123 | * so that should be close enough.
|
| 124 |
|
| 125 | name = &kallsyms_names[kallsyms_markers[pos >> 8]];
|
| 126 |
|
| 127 | |
| 128 | * Sequentially scan all the symbols up to the point we're searching
|
| 129 | * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
|
| 130 | * so we just need to add the len to the current pointer for every
|
| 131 | * symbol we wish to skip.
|
| 132 |
|
| 133 | for (i = 0; i < (pos & 0xFF); i++) {
|
| 134 | len = *name;
|
| 135 |
|
| 136 | |
| 137 | * If MSB is 1, it is a "big" symbol, so we need to look into
|
| 138 | * the next byte (and skip it, too).
|
| 139 |
|
| 140 | if ((len & 0x80) != 0)
|
| 141 | len = ((len & 0x7F) | (name[1] << 7)) + 1;
|
| 142 |
|
| 143 | name = name + len + 1;
|
| 144 | }
|
| 145 |
|
| 146 | return name - kallsyms_names;
|
| 147 | }
|
| 148 |
|
| 149 | unsigned long kallsyms_sym_address(int idx)
|
| 150 | {
|
| 151 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
|
| 152 | return kallsyms_addresses[idx];
|
| 153 |
|
| 154 |
|
| 155 | if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
|
| 156 | return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
|
| 157 |
|
| 158 |
|
| 159 | if (kallsyms_offsets[idx] >= 0)
|
| 160 | return kallsyms_offsets[idx];
|
| 161 |
|
| 162 |
|
| 163 | return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
|
| 164 | }
|
| 165 |
|
| 166 | static void cleanup_symbol_name(char *s)
|
| 167 | {
|
| 168 | char *res;
|
| 169 |
|
| 170 | if (!IS_ENABLED(CONFIG_LTO_CLANG))
|
| 171 | return;
|
| 172 |
|
| 173 | |
| 174 | * LLVM appends various suffixes for local functions and variables that
|
| 175 | * must be promoted to global scope as part of LTO. This can break
|
| 176 | * hooking of static functions with kprobes. '.' is not a valid
|
| 177 | * character in an identifier in C. Suffixes only in LLVM LTO observed:
|
| 178 | * - foo.llvm.[0-9a-f]+
|
| 179 |
|
| 180 | res = strstr(s, ".llvm.");
|
| 181 | if (res)
|
| 182 | *res = '\0';
|
| 183 |
|
| 184 | return;
|
| 185 | }
|
| 186 |
|
| 187 | static int compare_symbol_name(const char *name, char *namebuf)
|
| 188 | {
|
| 189 | |
| 190 | * cleanup_symbol_name() (see scripts/kallsyms.c) if clang lto is enabled.
|
| 191 | * To ensure correct bisection in kallsyms_lookup_names(), do
|
| 192 | * cleanup_symbol_name(namebuf) before comparing name and namebuf.
|
| 193 |
|
| 194 | cleanup_symbol_name(namebuf);
|
| 195 | return strcmp(name, namebuf);
|
| 196 | }
|
| 197 |
|
| 198 | static unsigned int get_symbol_seq(int index)
|
| 199 | {
|
| 200 | unsigned int i, seq = 0;
|
| 201 |
|
| 202 | for (i = 0; i < 3; i++)
|
| 203 | seq = (seq << 8) | kallsyms_seqs_of_names[3 * index + i];
|
| 204 |
|
| 205 | return seq;
|
| 206 | }
|
| 207 |
|
| 208 | static int kallsyms_lookup_names(const char *name,
|
| 209 | unsigned int *start,
|
| 210 | unsigned int *end)
|
| 211 | {
|
| 212 | int ret;
|
| 213 | int low, mid, high;
|
| 214 | unsigned int seq, off;
|
| 215 | char namebuf[KSYM_NAME_LEN];
|
| 216 |
|
| 217 | low = 0;
|
| 218 | high = kallsyms_num_syms - 1;
|
| 219 |
|
| 220 | while (low <= high) {
|
| 221 | mid = low + (high - low) / 2;
|
| 222 | seq = get_symbol_seq(mid);
|
| 223 | off = get_symbol_offset(seq);
|
| 224 | kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
|
| 225 | ret = compare_symbol_name(name, namebuf);
|
| 226 | if (ret > 0)
|
| 227 | low = mid + 1;
|
| 228 | else if (ret < 0)
|
| 229 | high = mid - 1;
|
| 230 | else
|
| 231 | break;
|
| 232 | }
|
| 233 |
|
| 234 | if (low > high)
|
| 235 | return -ESRCH;
|
| 236 |
|
| 237 | low = mid;
|
| 238 | while (low) {
|
| 239 | seq = get_symbol_seq(low - 1);
|
| 240 | off = get_symbol_offset(seq);
|
| 241 | kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
|
| 242 | if (compare_symbol_name(name, namebuf))
|
| 243 | break;
|
| 244 | low--;
|
| 245 | }
|
| 246 | *start = low;
|
| 247 |
|
| 248 | if (end) {
|
| 249 | high = mid;
|
| 250 | while (high < kallsyms_num_syms - 1) {
|
| 251 | seq = get_symbol_seq(high + 1);
|
| 252 | off = get_symbol_offset(seq);
|
| 253 | kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
|
| 254 | if (compare_symbol_name(name, namebuf))
|
| 255 | break;
|
| 256 | high++;
|
| 257 | }
|
| 258 | *end = high;
|
| 259 | }
|
| 260 |
|
| 261 | return 0;
|
| 262 | }
|
| 263 |
|
| 264 |
|
| 265 | unsigned long kallsyms_lookup_name(const char *name)
|
| 266 | {
|
| 267 | int ret;
|
| 268 | unsigned int i;
|
| 269 |
|
| 270 |
|
| 271 | if (!*name)
|
| 272 | return 0;
|
| 273 |
|
| 274 | ret = kallsyms_lookup_names(name, &i, NULL);
|
| 275 | if (!ret)
|
| 276 | return kallsyms_sym_address(get_symbol_seq(i));
|
| 277 |
|
| 278 | return module_kallsyms_lookup_name(name);
|
| 279 | }
|
| 280 |
|
| 281 | |
| 282 | * Iterate over all symbols in vmlinux. For symbols from modules use
|
| 283 | * module_kallsyms_on_each_symbol instead.
|
| 284 |
|
| 285 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long),
|
| 286 | void *data)
|
| 287 | {
|
| 288 | char namebuf[KSYM_NAME_LEN];
|
| 289 | unsigned long i;
|
| 290 | unsigned int off;
|
| 291 | int ret;
|
| 292 |
|
| 293 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
|
| 294 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
|
| 295 | ret = fn(data, namebuf, kallsyms_sym_address(i));
|
| 296 | if (ret != 0)
|
| 297 | return ret;
|
| 298 | cond_resched();
|
| 299 | }
|
| 300 | return 0;
|
| 301 | }
|
| 302 |
|
| 303 | int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long),
|
| 304 | const char *name, void *data)
|
| 305 | {
|
| 306 | int ret;
|
| 307 | unsigned int i, start, end;
|
| 308 |
|
| 309 | ret = kallsyms_lookup_names(name, &start, &end);
|
| 310 | if (ret)
|
| 311 | return 0;
|
| 312 |
|
| 313 | for (i = start; !ret && i <= end; i++) {
|
| 314 | ret = fn(data, kallsyms_sym_address(get_symbol_seq(i)));
|
| 315 | cond_resched();
|
| 316 | }
|
| 317 |
|
| 318 | return ret;
|
| 319 | }
|
| 320 |
|
| 321 | static unsigned long get_symbol_pos(unsigned long addr,
|
| 322 | unsigned long *symbolsize,
|
| 323 | unsigned long *offset)
|
| 324 | {
|
| 325 | unsigned long symbol_start = 0, symbol_end = 0;
|
| 326 | unsigned long i, low, high, mid;
|
| 327 |
|
| 328 |
|
| 329 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
|
| 330 | BUG_ON(!kallsyms_addresses);
|
| 331 | else
|
| 332 | BUG_ON(!kallsyms_offsets);
|
| 333 |
|
| 334 |
|
| 335 | low = 0;
|
| 336 | high = kallsyms_num_syms;
|
| 337 |
|
| 338 | while (high - low > 1) {
|
| 339 | mid = low + (high - low) / 2;
|
| 340 | if (kallsyms_sym_address(mid) <= addr)
|
| 341 | low = mid;
|
| 342 | else
|
| 343 | high = mid;
|
| 344 | }
|
| 345 |
|
| 346 | |
| 347 | * Search for the first aliased symbol. Aliased
|
| 348 | * symbols are symbols with the same address.
|
| 349 |
|
| 350 | while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
|
| 351 | --low;
|
| 352 |
|
| 353 | symbol_start = kallsyms_sym_address(low);
|
| 354 |
|
| 355 |
|
| 356 | for (i = low + 1; i < kallsyms_num_syms; i++) {
|
| 357 | if (kallsyms_sym_address(i) > symbol_start) {
|
| 358 | symbol_end = kallsyms_sym_address(i);
|
| 359 | break;
|
| 360 | }
|
| 361 | }
|
| 362 |
|
| 363 |
|
| 364 | if (!symbol_end) {
|
| 365 | if (is_kernel_inittext(addr))
|
| 366 | symbol_end = (unsigned long)_einittext;
|
| 367 | else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
|
| 368 | symbol_end = (unsigned long)_end;
|
| 369 | else
|
| 370 | symbol_end = (unsigned long)_etext;
|
| 371 | }
|
| 372 |
|
| 373 | if (symbolsize)
|
| 374 | *symbolsize = symbol_end - symbol_start;
|
| 375 | if (offset)
|
| 376 | *offset = addr - symbol_start;
|
| 377 |
|
| 378 | return low;
|
| 379 | }
|
| 380 |
|
| 381 | |
| 382 | * Lookup an address but don't bother to find any names.
|
| 383 |
|
| 384 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
|
| 385 | unsigned long *offset)
|
| 386 | {
|
| 387 | char namebuf[KSYM_NAME_LEN];
|
| 388 |
|
| 389 | if (is_ksym_addr(addr)) {
|
| 390 | get_symbol_pos(addr, symbolsize, offset);
|
| 391 | return 1;
|
| 392 | }
|
| 393 | return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) ||
|
| 394 | !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
|
| 395 | }
|
| 396 |
|
| 397 | static const char *kallsyms_lookup_buildid(unsigned long addr,
|
| 398 | unsigned long *symbolsize,
|
| 399 | unsigned long *offset, char **modname,
|
| 400 | const unsigned char **modbuildid, char *namebuf)
|
| 401 | {
|
| 402 | const char *ret;
|
| 403 |
|
| 404 | namebuf[KSYM_NAME_LEN - 1] = 0;
|
| 405 | namebuf[0] = 0;
|
| 406 |
|
| 407 | if (is_ksym_addr(addr)) {
|
| 408 | unsigned long pos;
|
| 409 |
|
| 410 | pos = get_symbol_pos(addr, symbolsize, offset);
|
| 411 |
|
| 412 | kallsyms_expand_symbol(get_symbol_offset(pos),
|
| 413 | namebuf, KSYM_NAME_LEN);
|
| 414 | if (modname)
|
| 415 | *modname = NULL;
|
| 416 | if (modbuildid)
|
| 417 | *modbuildid = NULL;
|
| 418 |
|
| 419 | ret = namebuf;
|
| 420 | goto found;
|
| 421 | }
|
| 422 |
|
| 423 |
|
| 424 | ret = module_address_lookup(addr, symbolsize, offset,
|
| 425 | modname, modbuildid, namebuf);
|
| 426 | if (!ret)
|
| 427 | ret = bpf_address_lookup(addr, symbolsize,
|
| 428 | offset, modname, namebuf);
|
| 429 |
|
| 430 | if (!ret)
|
| 431 | ret = ftrace_mod_address_lookup(addr, symbolsize,
|
| 432 | offset, modname, namebuf);
|
| 433 |
|
| 434 | found:
|
| 435 | cleanup_symbol_name(namebuf);
|
| 436 | return ret;
|
| 437 | }
|
| 438 |
|
| 439 | |
| 440 | * Lookup an address
|
| 441 | * - modname is set to NULL if it's in the kernel.
|
| 442 | * - We guarantee that the returned name is valid until we reschedule even if.
|
| 443 | * It resides in a module.
|
| 444 | * - We also guarantee that modname will be valid until rescheduled.
|
| 445 |
|
| 446 | const char *kallsyms_lookup(unsigned long addr,
|
| 447 | unsigned long *symbolsize,
|
| 448 | unsigned long *offset,
|
| 449 | char **modname, char *namebuf)
|
| 450 | {
|
| 451 | return kallsyms_lookup_buildid(addr, symbolsize, offset, modname,
|
| 452 | NULL, namebuf);
|
| 453 | }
|
| 454 |
|
| 455 | int lookup_symbol_name(unsigned long addr, char *symname)
|
| 456 | {
|
| 457 | int res;
|
| 458 |
|
| 459 | symname[0] = '\0';
|
| 460 | symname[KSYM_NAME_LEN - 1] = '\0';
|
| 461 |
|
| 462 | if (is_ksym_addr(addr)) {
|
| 463 | unsigned long pos;
|
| 464 |
|
| 465 | pos = get_symbol_pos(addr, NULL, NULL);
|
| 466 |
|
| 467 | kallsyms_expand_symbol(get_symbol_offset(pos),
|
| 468 | symname, KSYM_NAME_LEN);
|
| 469 | goto found;
|
| 470 | }
|
| 471 |
|
| 472 | res = lookup_module_symbol_name(addr, symname);
|
| 473 | if (res)
|
| 474 | return res;
|
| 475 |
|
| 476 | found:
|
| 477 | cleanup_symbol_name(symname);
|
| 478 | return 0;
|
| 479 | }
|
| 480 |
|
| 481 |
|
| 482 | static int __sprint_symbol(char *buffer, unsigned long address,
|
| 483 | int symbol_offset, int add_offset, int add_buildid)
|
| 484 | {
|
| 485 | char *modname;
|
| 486 | const unsigned char *buildid;
|
| 487 | const char *name;
|
| 488 | unsigned long offset, size;
|
| 489 | int len;
|
| 490 |
|
| 491 | address += symbol_offset;
|
| 492 | name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid,
|
| 493 | buffer);
|
| 494 | if (!name)
|
| 495 | return sprintf(buffer, "0x%lx", address - symbol_offset);
|
| 496 |
|
| 497 | if (name != buffer)
|
| 498 | strcpy(buffer, name);
|
| 499 | len = strlen(buffer);
|
| 500 | offset -= symbol_offset;
|
| 501 |
|
| 502 | if (add_offset)
|
| 503 | len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
|
| 504 |
|
| 505 | if (modname) {
|
| 506 | len += sprintf(buffer + len, " [%s", modname);
|
| 507 | #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
|
| 508 | if (add_buildid && buildid) {
|
| 509 |
|
| 510 | #if IS_ENABLED(CONFIG_MODULES)
|
| 511 | static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
|
| 512 | #endif
|
| 513 | len += sprintf(buffer + len, " %20phN", buildid);
|
| 514 | }
|
| 515 | #endif
|
| 516 | len += sprintf(buffer + len, "]");
|
| 517 | }
|
| 518 |
|
| 519 | return len;
|
| 520 | }
|
| 521 |
|
| 522 | |
| 523 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer
|
| 524 | * @buffer: buffer to be stored
|
| 525 | * @address: address to lookup
|
| 526 | *
|
| 527 | * This function looks up a kernel symbol with @address and stores its name,
|
| 528 | * offset, size and module name to @buffer if possible. If no symbol was found,
|
| 529 | * just saves its @address as is.
|
| 530 | *
|
| 531 | * This function returns the number of bytes stored in @buffer.
|
| 532 |
|
| 533 | int sprint_symbol(char *buffer, unsigned long address)
|
| 534 | {
|
| 535 | return __sprint_symbol(buffer, address, 0, 1, 0);
|
| 536 | }
|
| 537 | EXPORT_SYMBOL_GPL(sprint_symbol);
|
| 538 |
|
| 539 | |
| 540 | * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
|
| 541 | * @buffer: buffer to be stored
|
| 542 | * @address: address to lookup
|
| 543 | *
|
| 544 | * This function looks up a kernel symbol with @address and stores its name,
|
| 545 | * offset, size, module name and module build ID to @buffer if possible. If no
|
| 546 | * symbol was found, just saves its @address as is.
|
| 547 | *
|
| 548 | * This function returns the number of bytes stored in @buffer.
|
| 549 |
|
| 550 | int sprint_symbol_build_id(char *buffer, unsigned long address)
|
| 551 | {
|
| 552 | return __sprint_symbol(buffer, address, 0, 1, 1);
|
| 553 | }
|
| 554 | EXPORT_SYMBOL_GPL(sprint_symbol_build_id);
|
| 555 |
|
| 556 | |
| 557 | * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
|
| 558 | * @buffer: buffer to be stored
|
| 559 | * @address: address to lookup
|
| 560 | *
|
| 561 | * This function looks up a kernel symbol with @address and stores its name
|
| 562 | * and module name to @buffer if possible. If no symbol was found, just saves
|
| 563 | * its @address as is.
|
| 564 | *
|
| 565 | * This function returns the number of bytes stored in @buffer.
|
| 566 |
|
| 567 | int sprint_symbol_no_offset(char *buffer, unsigned long address)
|
| 568 | {
|
| 569 | return __sprint_symbol(buffer, address, 0, 0, 0);
|
| 570 | }
|
| 571 | EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
|
| 572 |
|
| 573 | |
| 574 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
|
| 575 | * @buffer: buffer to be stored
|
| 576 | * @address: address to lookup
|
| 577 | *
|
| 578 | * This function is for stack backtrace and does the same thing as
|
| 579 | * sprint_symbol() but with modified/decreased @address. If there is a
|
| 580 | * tail-call to the function marked "noreturn", gcc optimized out code after
|
| 581 | * the call so that the stack-saved return address could point outside of the
|
| 582 | * caller. This function ensures that kallsyms will find the original caller
|
| 583 | * by decreasing @address.
|
| 584 | *
|
| 585 | * This function returns the number of bytes stored in @buffer.
|
| 586 |
|
| 587 | int sprint_backtrace(char *buffer, unsigned long address)
|
| 588 | {
|
| 589 | return __sprint_symbol(buffer, address, -1, 1, 0);
|
| 590 | }
|
| 591 |
|
| 592 | |
| 593 | * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
|
| 594 | * @buffer: buffer to be stored
|
| 595 | * @address: address to lookup
|
| 596 | *
|
| 597 | * This function is for stack backtrace and does the same thing as
|
| 598 | * sprint_symbol() but with modified/decreased @address. If there is a
|
| 599 | * tail-call to the function marked "noreturn", gcc optimized out code after
|
| 600 | * the call so that the stack-saved return address could point outside of the
|
| 601 | * caller. This function ensures that kallsyms will find the original caller
|
| 602 | * by decreasing @address. This function also appends the module build ID to
|
| 603 | * the @buffer if @address is within a kernel module.
|
| 604 | *
|
| 605 | * This function returns the number of bytes stored in @buffer.
|
| 606 |
|
| 607 | int sprint_backtrace_build_id(char *buffer, unsigned long address)
|
| 608 | {
|
| 609 | return __sprint_symbol(buffer, address, -1, 1, 1);
|
| 610 | }
|
| 611 |
|
| 612 |
|
| 613 | struct kallsym_iter {
|
| 614 | loff_t pos;
|
| 615 | loff_t pos_mod_end;
|
| 616 | loff_t pos_ftrace_mod_end;
|
| 617 | loff_t pos_bpf_end;
|
| 618 | unsigned long value;
|
| 619 | unsigned int nameoff;
|
| 620 | char type;
|
| 621 | char name[KSYM_NAME_LEN];
|
| 622 | char module_name[MODULE_NAME_LEN];
|
| 623 | int exported;
|
| 624 | int show_value;
|
| 625 | };
|
| 626 |
|
| 627 | static int get_ksymbol_mod(struct kallsym_iter *iter)
|
| 628 | {
|
| 629 | int ret = module_get_kallsym(iter->pos - kallsyms_num_syms,
|
| 630 | &iter->value, &iter->type,
|
| 631 | iter->name, iter->module_name,
|
| 632 | &iter->exported);
|
| 633 | if (ret < 0) {
|
| 634 | iter->pos_mod_end = iter->pos;
|
| 635 | return 0;
|
| 636 | }
|
| 637 |
|
| 638 | return 1;
|
| 639 | }
|
| 640 |
|
| 641 | |
| 642 | * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
|
| 643 | * purposes. In that case "__builtin__ftrace" is used as a module name, even
|
| 644 | * though "__builtin__ftrace" is not a module.
|
| 645 |
|
| 646 | static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
|
| 647 | {
|
| 648 | int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
|
| 649 | &iter->value, &iter->type,
|
| 650 | iter->name, iter->module_name,
|
| 651 | &iter->exported);
|
| 652 | if (ret < 0) {
|
| 653 | iter->pos_ftrace_mod_end = iter->pos;
|
| 654 | return 0;
|
| 655 | }
|
| 656 |
|
| 657 | return 1;
|
| 658 | }
|
| 659 |
|
| 660 | static int get_ksymbol_bpf(struct kallsym_iter *iter)
|
| 661 | {
|
| 662 | int ret;
|
| 663 |
|
| 664 | strscpy(iter->module_name, "bpf", MODULE_NAME_LEN);
|
| 665 | iter->exported = 0;
|
| 666 | ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
|
| 667 | &iter->value, &iter->type,
|
| 668 | iter->name);
|
| 669 | if (ret < 0) {
|
| 670 | iter->pos_bpf_end = iter->pos;
|
| 671 | return 0;
|
| 672 | }
|
| 673 |
|
| 674 | return 1;
|
| 675 | }
|
| 676 |
|
| 677 | |
| 678 | * This uses "__builtin__kprobes" as a module name for symbols for pages
|
| 679 | * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
|
| 680 | * module.
|
| 681 |
|
| 682 | static int get_ksymbol_kprobe(struct kallsym_iter *iter)
|
| 683 | {
|
| 684 | strscpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
|
| 685 | iter->exported = 0;
|
| 686 | return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
|
| 687 | &iter->value, &iter->type,
|
| 688 | iter->name) < 0 ? 0 : 1;
|
| 689 | }
|
| 690 |
|
| 691 |
|
| 692 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
|
| 693 | {
|
| 694 | unsigned off = iter->nameoff;
|
| 695 |
|
| 696 | iter->module_name[0] = '\0';
|
| 697 | iter->value = kallsyms_sym_address(iter->pos);
|
| 698 |
|
| 699 | iter->type = kallsyms_get_symbol_type(off);
|
| 700 |
|
| 701 | off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
|
| 702 |
|
| 703 | return off - iter->nameoff;
|
| 704 | }
|
| 705 |
|
| 706 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
|
| 707 | {
|
| 708 | iter->name[0] = '\0';
|
| 709 | iter->nameoff = get_symbol_offset(new_pos);
|
| 710 | iter->pos = new_pos;
|
| 711 | if (new_pos == 0) {
|
| 712 | iter->pos_mod_end = 0;
|
| 713 | iter->pos_ftrace_mod_end = 0;
|
| 714 | iter->pos_bpf_end = 0;
|
| 715 | }
|
| 716 | }
|
| 717 |
|
| 718 | |
| 719 | * The end position (last + 1) of each additional kallsyms section is recorded
|
| 720 | * in iter->pos_..._end as each section is added, and so can be used to
|
| 721 | * determine which get_ksymbol_...() function to call next.
|
| 722 |
|
| 723 | static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
|
| 724 | {
|
| 725 | iter->pos = pos;
|
| 726 |
|
| 727 | if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
|
| 728 | get_ksymbol_mod(iter))
|
| 729 | return 1;
|
| 730 |
|
| 731 | if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
|
| 732 | get_ksymbol_ftrace_mod(iter))
|
| 733 | return 1;
|
| 734 |
|
| 735 | if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
|
| 736 | get_ksymbol_bpf(iter))
|
| 737 | return 1;
|
| 738 |
|
| 739 | return get_ksymbol_kprobe(iter);
|
| 740 | }
|
| 741 |
|
| 742 |
|
| 743 | static int update_iter(struct kallsym_iter *iter, loff_t pos)
|
| 744 | {
|
| 745 |
|
| 746 | if (pos >= kallsyms_num_syms)
|
| 747 | return update_iter_mod(iter, pos);
|
| 748 |
|
| 749 |
|
| 750 | if (pos != iter->pos)
|
| 751 | reset_iter(iter, pos);
|
| 752 |
|
| 753 | iter->nameoff += get_ksymbol_core(iter);
|
| 754 | iter->pos++;
|
| 755 |
|
| 756 | return 1;
|
| 757 | }
|
| 758 |
|
| 759 | static void *s_next(struct seq_file *m, void *p, loff_t *pos)
|
| 760 | {
|
| 761 | (*pos)++;
|
| 762 |
|
| 763 | if (!update_iter(m->private, *pos))
|
| 764 | return NULL;
|
| 765 | return p;
|
| 766 | }
|
| 767 |
|
| 768 | static void *s_start(struct seq_file *m, loff_t *pos)
|
| 769 | {
|
| 770 | if (!update_iter(m->private, *pos))
|
| 771 | return NULL;
|
| 772 | return m->private;
|
| 773 | }
|
| 774 |
|
| 775 | static void s_stop(struct seq_file *m, void *p)
|
| 776 | {
|
| 777 | }
|
| 778 |
|
| 779 | static int s_show(struct seq_file *m, void *p)
|
| 780 | {
|
| 781 | void *value;
|
| 782 | struct kallsym_iter *iter = m->private;
|
| 783 |
|
| 784 |
|
| 785 | if (!iter->name[0])
|
| 786 | return 0;
|
| 787 |
|
| 788 | value = iter->show_value ? (void *)iter->value : NULL;
|
| 789 |
|
| 790 | if (iter->module_name[0]) {
|
| 791 | char type;
|
| 792 |
|
| 793 | |
| 794 | * Label it "global" if it is exported,
|
| 795 | * "local" if not exported.
|
| 796 |
|
| 797 | type = iter->exported ? toupper(iter->type) :
|
| 798 | tolower(iter->type);
|
| 799 | seq_printf(m, "%px %c %s\t[%s]\n", value,
|
| 800 | type, iter->name, iter->module_name);
|
| 801 | } else
|
| 802 | seq_printf(m, "%px %c %s\n", value,
|
| 803 | iter->type, iter->name);
|
| 804 | return 0;
|
| 805 | }
|
| 806 |
|
| 807 | static const struct seq_operations kallsyms_op = {
|
| 808 | .start = s_start,
|
| 809 | .next = s_next,
|
| 810 | .stop = s_stop,
|
| 811 | .show = s_show
|
| 812 | };
|
| 813 |
|
| 814 | #ifdef CONFIG_BPF_SYSCALL
|
| 815 |
|
| 816 | struct bpf_iter__ksym {
|
| 817 | __bpf_md_ptr(struct bpf_iter_meta *, meta);
|
| 818 | __bpf_md_ptr(struct kallsym_iter *, ksym);
|
| 819 | };
|
| 820 |
|
| 821 | static int ksym_prog_seq_show(struct seq_file *m, bool in_stop)
|
| 822 | {
|
| 823 | struct bpf_iter__ksym ctx;
|
| 824 | struct bpf_iter_meta meta;
|
| 825 | struct bpf_prog *prog;
|
| 826 |
|
| 827 | meta.seq = m;
|
| 828 | prog = bpf_iter_get_info(&meta, in_stop);
|
| 829 | if (!prog)
|
| 830 | return 0;
|
| 831 |
|
| 832 | ctx.meta = &meta;
|
| 833 | ctx.ksym = m ? m->private : NULL;
|
| 834 | return bpf_iter_run_prog(prog, &ctx);
|
| 835 | }
|
| 836 |
|
| 837 | static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p)
|
| 838 | {
|
| 839 | return ksym_prog_seq_show(m, false);
|
| 840 | }
|
| 841 |
|
| 842 | static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p)
|
| 843 | {
|
| 844 | if (!p)
|
| 845 | (void) ksym_prog_seq_show(m, true);
|
| 846 | else
|
| 847 | s_stop(m, p);
|
| 848 | }
|
| 849 |
|
| 850 | static const struct seq_operations bpf_iter_ksym_ops = {
|
| 851 | .start = s_start,
|
| 852 | .next = s_next,
|
| 853 | .stop = bpf_iter_ksym_seq_stop,
|
| 854 | .show = bpf_iter_ksym_seq_show,
|
| 855 | };
|
| 856 |
|
| 857 | static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux)
|
| 858 | {
|
| 859 | struct kallsym_iter *iter = priv_data;
|
| 860 |
|
| 861 | reset_iter(iter, 0);
|
| 862 |
|
| 863 | |
| 864 | * credentials to tell BPF iterators if values should be shown.
|
| 865 |
|
| 866 | iter->show_value = kallsyms_show_value(current_cred());
|
| 867 |
|
| 868 | return 0;
|
| 869 | }
|
| 870 |
|
| 871 | DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym)
|
| 872 |
|
| 873 | static const struct bpf_iter_seq_info ksym_iter_seq_info = {
|
| 874 | .seq_ops = &bpf_iter_ksym_ops,
|
| 875 | .init_seq_private = bpf_iter_ksym_init,
|
| 876 | .fini_seq_private = NULL,
|
| 877 | .seq_priv_size = sizeof(struct kallsym_iter),
|
| 878 | };
|
| 879 |
|
| 880 | static struct bpf_iter_reg ksym_iter_reg_info = {
|
| 881 | .target = "ksym",
|
| 882 | .feature = BPF_ITER_RESCHED,
|
| 883 | .ctx_arg_info_size = 1,
|
| 884 | .ctx_arg_info = {
|
| 885 | { offsetof(struct bpf_iter__ksym, ksym),
|
| 886 | PTR_TO_BTF_ID_OR_NULL },
|
| 887 | },
|
| 888 | .seq_info = &ksym_iter_seq_info,
|
| 889 | };
|
| 890 |
|
| 891 | BTF_ID_LIST(btf_ksym_iter_id)
|
| 892 | BTF_ID(struct, kallsym_iter)
|
| 893 |
|
| 894 | static int __init bpf_ksym_iter_register(void)
|
| 895 | {
|
| 896 | ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id;
|
| 897 | return bpf_iter_reg_target(&ksym_iter_reg_info);
|
| 898 | }
|
| 899 |
|
| 900 | late_initcall(bpf_ksym_iter_register);
|
| 901 |
|
| 902 | #endif
|
| 903 |
|
| 904 | static int kallsyms_open(struct inode *inode, struct file *file)
|
| 905 | {
|
| 906 | |
| 907 | * We keep iterator in m->private, since normal case is to
|
| 908 | * s_start from where we left off, so we avoid doing
|
| 909 | * using get_symbol_offset for every symbol.
|
| 910 |
|
| 911 | struct kallsym_iter *iter;
|
| 912 | iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
|
| 913 | if (!iter)
|
| 914 | return -ENOMEM;
|
| 915 | reset_iter(iter, 0);
|
| 916 |
|
| 917 | |
| 918 | * Instead of checking this on every s_show() call, cache
|
| 919 | * the result here at open time.
|
| 920 |
|
| 921 | iter->show_value = kallsyms_show_value(file->f_cred);
|
| 922 | return 0;
|
| 923 | }
|
| 924 |
|
| 925 | #ifdef CONFIG_KGDB_KDB
|
| 926 | const char *kdb_walk_kallsyms(loff_t *pos)
|
| 927 | {
|
| 928 | static struct kallsym_iter kdb_walk_kallsyms_iter;
|
| 929 | if (*pos == 0) {
|
| 930 | memset(&kdb_walk_kallsyms_iter, 0,
|
| 931 | sizeof(kdb_walk_kallsyms_iter));
|
| 932 | reset_iter(&kdb_walk_kallsyms_iter, 0);
|
| 933 | }
|
| 934 | while (1) {
|
| 935 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
|
| 936 | return NULL;
|
| 937 | ++*pos;
|
| 938 |
|
| 939 | if (kdb_walk_kallsyms_iter.name[0])
|
| 940 | return kdb_walk_kallsyms_iter.name;
|
| 941 | }
|
| 942 | }
|
| 943 | #endif
|
| 944 |
|
| 945 | static const struct proc_ops kallsyms_proc_ops = {
|
| 946 | .proc_open = kallsyms_open,
|
| 947 | .proc_read = seq_read,
|
| 948 | .proc_lseek = seq_lseek,
|
| 949 | .proc_release = seq_release_private,
|
| 950 | };
|
| 951 |
|
| 952 | static int __init kallsyms_init(void)
|
| 953 | {
|
| 954 | proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
|
| 955 | return 0;
|
| 956 | }
|
| 957 | device_initcall(kallsyms_init);
|