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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
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> | |
1da177e4 LT |
16 | #include <linux/init.h> |
17 | #include <linux/seq_file.h> | |
18 | #include <linux/fs.h> | |
67fc4e0c | 19 | #include <linux/kdb.h> |
1da177e4 LT |
20 | #include <linux/err.h> |
21 | #include <linux/proc_fs.h> | |
4e57b681 | 22 | #include <linux/sched.h> /* for cond_resched */ |
07354a00 | 23 | #include <linux/ctype.h> |
5a0e3ad6 | 24 | #include <linux/slab.h> |
74451e66 | 25 | #include <linux/filter.h> |
aba4b5c2 | 26 | #include <linux/ftrace.h> |
d002b8bc | 27 | #include <linux/kprobes.h> |
9294523e | 28 | #include <linux/build_bug.h> |
52f5684c | 29 | #include <linux/compiler.h> |
9294523e SB |
30 | #include <linux/module.h> |
31 | #include <linux/kernel.h> | |
1da177e4 | 32 | |
ad6ccfad MK |
33 | /* |
34 | * These will be re-linked against their real values | |
35 | * during the second link stage. | |
36 | */ | |
52f5684c | 37 | extern const unsigned long kallsyms_addresses[] __weak; |
2213e9a6 | 38 | extern const int kallsyms_offsets[] __weak; |
52f5684c | 39 | extern const u8 kallsyms_names[] __weak; |
1da177e4 | 40 | |
ad6ccfad MK |
41 | /* |
42 | * Tell the compiler that the count isn't in the small data section if the arch | |
43 | * has one (eg: FRV). | |
9e6c1e63 | 44 | */ |
80ffbaa5 | 45 | extern const unsigned int kallsyms_num_syms |
33def849 | 46 | __section(".rodata") __attribute__((weak)); |
9e6c1e63 | 47 | |
2213e9a6 | 48 | extern const unsigned long kallsyms_relative_base |
33def849 | 49 | __section(".rodata") __attribute__((weak)); |
2213e9a6 | 50 | |
cde26a6e | 51 | extern const char kallsyms_token_table[] __weak; |
52f5684c | 52 | extern const u16 kallsyms_token_index[] __weak; |
1da177e4 | 53 | |
80ffbaa5 | 54 | extern const unsigned int kallsyms_markers[] __weak; |
1da177e4 | 55 | |
ad6ccfad MK |
56 | /* |
57 | * Expand a compressed symbol data into the resulting uncompressed string, | |
e3f26752 | 58 | * if uncompressed string is too long (>= maxlen), it will be truncated, |
ad6ccfad MK |
59 | * given the offset to where the symbol is in the compressed stream. |
60 | */ | |
e3f26752 CG |
61 | static unsigned int kallsyms_expand_symbol(unsigned int off, |
62 | char *result, size_t maxlen) | |
1da177e4 LT |
63 | { |
64 | int len, skipped_first = 0; | |
cde26a6e MY |
65 | const char *tptr; |
66 | const u8 *data; | |
1da177e4 | 67 | |
ad6ccfad | 68 | /* Get the compressed symbol length from the first symbol byte. */ |
1da177e4 LT |
69 | data = &kallsyms_names[off]; |
70 | len = *data; | |
71 | data++; | |
72 | ||
ad6ccfad MK |
73 | /* |
74 | * Update the offset to return the offset for the next symbol on | |
75 | * the compressed stream. | |
76 | */ | |
1da177e4 LT |
77 | off += len + 1; |
78 | ||
ad6ccfad MK |
79 | /* |
80 | * For every byte on the compressed symbol data, copy the table | |
81 | * entry for that byte. | |
82 | */ | |
83 | while (len) { | |
84 | tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; | |
1da177e4 LT |
85 | data++; |
86 | len--; | |
87 | ||
88 | while (*tptr) { | |
ad6ccfad | 89 | if (skipped_first) { |
e3f26752 CG |
90 | if (maxlen <= 1) |
91 | goto tail; | |
1da177e4 LT |
92 | *result = *tptr; |
93 | result++; | |
e3f26752 | 94 | maxlen--; |
1da177e4 LT |
95 | } else |
96 | skipped_first = 1; | |
97 | tptr++; | |
98 | } | |
99 | } | |
100 | ||
e3f26752 CG |
101 | tail: |
102 | if (maxlen) | |
103 | *result = '\0'; | |
1da177e4 | 104 | |
ad6ccfad | 105 | /* Return to offset to the next symbol. */ |
1da177e4 LT |
106 | return off; |
107 | } | |
108 | ||
ad6ccfad MK |
109 | /* |
110 | * Get symbol type information. This is encoded as a single char at the | |
111 | * beginning of the symbol name. | |
112 | */ | |
1da177e4 LT |
113 | static char kallsyms_get_symbol_type(unsigned int off) |
114 | { | |
ad6ccfad MK |
115 | /* |
116 | * Get just the first code, look it up in the token table, | |
117 | * and return the first char from this token. | |
118 | */ | |
119 | return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; | |
1da177e4 LT |
120 | } |
121 | ||
122 | ||
ad6ccfad MK |
123 | /* |
124 | * Find the offset on the compressed stream given and index in the | |
125 | * kallsyms array. | |
126 | */ | |
1da177e4 LT |
127 | static unsigned int get_symbol_offset(unsigned long pos) |
128 | { | |
aad09470 | 129 | const u8 *name; |
1da177e4 LT |
130 | int i; |
131 | ||
ad6ccfad MK |
132 | /* |
133 | * Use the closest marker we have. We have markers every 256 positions, | |
134 | * so that should be close enough. | |
135 | */ | |
136 | name = &kallsyms_names[kallsyms_markers[pos >> 8]]; | |
1da177e4 | 137 | |
ad6ccfad MK |
138 | /* |
139 | * Sequentially scan all the symbols up to the point we're searching | |
140 | * for. Every symbol is stored in a [<len>][<len> bytes of data] format, | |
141 | * so we just need to add the len to the current pointer for every | |
142 | * symbol we wish to skip. | |
143 | */ | |
144 | for (i = 0; i < (pos & 0xFF); i++) | |
1da177e4 LT |
145 | name = name + (*name) + 1; |
146 | ||
147 | return name - kallsyms_names; | |
148 | } | |
149 | ||
2213e9a6 AB |
150 | static unsigned long kallsyms_sym_address(int idx) |
151 | { | |
152 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) | |
153 | return kallsyms_addresses[idx]; | |
154 | ||
155 | /* values are unsigned offsets if --absolute-percpu is not in effect */ | |
156 | if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU)) | |
157 | return kallsyms_relative_base + (u32)kallsyms_offsets[idx]; | |
158 | ||
159 | /* ...otherwise, positive offsets are absolute values */ | |
160 | if (kallsyms_offsets[idx] >= 0) | |
161 | return kallsyms_offsets[idx]; | |
162 | ||
163 | /* ...and negative offsets are relative to kallsyms_relative_base - 1 */ | |
164 | return kallsyms_relative_base - 1 - kallsyms_offsets[idx]; | |
165 | } | |
166 | ||
8b8e6b5d ST |
167 | #if defined(CONFIG_CFI_CLANG) && defined(CONFIG_LTO_CLANG_THIN) |
168 | /* | |
169 | * LLVM appends a hash to static function names when ThinLTO and CFI are | |
170 | * both enabled, i.e. foo() becomes foo$707af9a22804d33c81801f27dcfe489b. | |
171 | * This causes confusion and potentially breaks user space tools, so we | |
172 | * strip the suffix from expanded symbol names. | |
173 | */ | |
174 | static inline bool cleanup_symbol_name(char *s) | |
175 | { | |
176 | char *res; | |
177 | ||
178 | res = strrchr(s, '$'); | |
179 | if (res) | |
180 | *res = '\0'; | |
181 | ||
182 | return res != NULL; | |
183 | } | |
184 | #else | |
185 | static inline bool cleanup_symbol_name(char *s) { return false; } | |
186 | #endif | |
187 | ||
1da177e4 LT |
188 | /* Lookup the address for this symbol. Returns 0 if not found. */ |
189 | unsigned long kallsyms_lookup_name(const char *name) | |
190 | { | |
9281acea | 191 | char namebuf[KSYM_NAME_LEN]; |
1da177e4 LT |
192 | unsigned long i; |
193 | unsigned int off; | |
194 | ||
195 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
e3f26752 | 196 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
1da177e4 LT |
197 | |
198 | if (strcmp(namebuf, name) == 0) | |
2213e9a6 | 199 | return kallsyms_sym_address(i); |
8b8e6b5d ST |
200 | |
201 | if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0) | |
202 | return kallsyms_sym_address(i); | |
1da177e4 LT |
203 | } |
204 | return module_kallsyms_lookup_name(name); | |
205 | } | |
1da177e4 | 206 | |
3e355205 | 207 | #ifdef CONFIG_LIVEPATCH |
013c1667 CH |
208 | /* |
209 | * Iterate over all symbols in vmlinux. For symbols from modules use | |
210 | * module_kallsyms_on_each_symbol instead. | |
211 | */ | |
75a66614 AK |
212 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, |
213 | unsigned long), | |
214 | void *data) | |
215 | { | |
216 | char namebuf[KSYM_NAME_LEN]; | |
217 | unsigned long i; | |
218 | unsigned int off; | |
219 | int ret; | |
220 | ||
221 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
e3f26752 | 222 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
2213e9a6 | 223 | ret = fn(data, namebuf, NULL, kallsyms_sym_address(i)); |
75a66614 AK |
224 | if (ret != 0) |
225 | return ret; | |
226 | } | |
013c1667 | 227 | return 0; |
75a66614 | 228 | } |
3e355205 | 229 | #endif /* CONFIG_LIVEPATCH */ |
75a66614 | 230 | |
ffc50891 FBH |
231 | static unsigned long get_symbol_pos(unsigned long addr, |
232 | unsigned long *symbolsize, | |
233 | unsigned long *offset) | |
234 | { | |
235 | unsigned long symbol_start = 0, symbol_end = 0; | |
236 | unsigned long i, low, high, mid; | |
237 | ||
2ea03891 | 238 | /* This kernel should never had been booted. */ |
2213e9a6 AB |
239 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) |
240 | BUG_ON(!kallsyms_addresses); | |
241 | else | |
242 | BUG_ON(!kallsyms_offsets); | |
2ea03891 | 243 | |
ad6ccfad | 244 | /* Do a binary search on the sorted kallsyms_addresses array. */ |
ffc50891 FBH |
245 | low = 0; |
246 | high = kallsyms_num_syms; | |
247 | ||
248 | while (high - low > 1) { | |
2fc9c4e1 | 249 | mid = low + (high - low) / 2; |
2213e9a6 | 250 | if (kallsyms_sym_address(mid) <= addr) |
ffc50891 FBH |
251 | low = mid; |
252 | else | |
253 | high = mid; | |
254 | } | |
255 | ||
256 | /* | |
ad6ccfad MK |
257 | * Search for the first aliased symbol. Aliased |
258 | * symbols are symbols with the same address. | |
ffc50891 | 259 | */ |
2213e9a6 | 260 | while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low)) |
ffc50891 FBH |
261 | --low; |
262 | ||
2213e9a6 | 263 | symbol_start = kallsyms_sym_address(low); |
ffc50891 | 264 | |
ad6ccfad | 265 | /* Search for next non-aliased symbol. */ |
ffc50891 | 266 | for (i = low + 1; i < kallsyms_num_syms; i++) { |
2213e9a6 AB |
267 | if (kallsyms_sym_address(i) > symbol_start) { |
268 | symbol_end = kallsyms_sym_address(i); | |
ffc50891 FBH |
269 | break; |
270 | } | |
271 | } | |
272 | ||
ad6ccfad | 273 | /* If we found no next symbol, we use the end of the section. */ |
ffc50891 FBH |
274 | if (!symbol_end) { |
275 | if (is_kernel_inittext(addr)) | |
276 | symbol_end = (unsigned long)_einittext; | |
63b23e2c | 277 | else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) |
ffc50891 FBH |
278 | symbol_end = (unsigned long)_end; |
279 | else | |
280 | symbol_end = (unsigned long)_etext; | |
281 | } | |
282 | ||
ffb45122 AD |
283 | if (symbolsize) |
284 | *symbolsize = symbol_end - symbol_start; | |
285 | if (offset) | |
286 | *offset = addr - symbol_start; | |
ffc50891 FBH |
287 | |
288 | return low; | |
289 | } | |
290 | ||
291 | /* | |
292 | * Lookup an address but don't bother to find any names. | |
293 | */ | |
294 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, | |
295 | unsigned long *offset) | |
296 | { | |
6dd06c9f | 297 | char namebuf[KSYM_NAME_LEN]; |
74451e66 | 298 | |
2a1a3fa0 MZ |
299 | if (is_ksym_addr(addr)) { |
300 | get_symbol_pos(addr, symbolsize, offset); | |
301 | return 1; | |
302 | } | |
9294523e | 303 | return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) || |
74451e66 | 304 | !!__bpf_address_lookup(addr, symbolsize, offset, namebuf); |
ffc50891 FBH |
305 | } |
306 | ||
9294523e SB |
307 | static const char *kallsyms_lookup_buildid(unsigned long addr, |
308 | unsigned long *symbolsize, | |
309 | unsigned long *offset, char **modname, | |
310 | const unsigned char **modbuildid, char *namebuf) | |
1da177e4 | 311 | { |
74451e66 DB |
312 | const char *ret; |
313 | ||
9281acea | 314 | namebuf[KSYM_NAME_LEN - 1] = 0; |
1da177e4 LT |
315 | namebuf[0] = 0; |
316 | ||
ffc50891 FBH |
317 | if (is_ksym_addr(addr)) { |
318 | unsigned long pos; | |
1da177e4 | 319 | |
ffc50891 | 320 | pos = get_symbol_pos(addr, symbolsize, offset); |
1da177e4 | 321 | /* Grab name */ |
e3f26752 CG |
322 | kallsyms_expand_symbol(get_symbol_offset(pos), |
323 | namebuf, KSYM_NAME_LEN); | |
7a74fc49 KM |
324 | if (modname) |
325 | *modname = NULL; | |
9294523e SB |
326 | if (modbuildid) |
327 | *modbuildid = NULL; | |
8b8e6b5d ST |
328 | |
329 | ret = namebuf; | |
330 | goto found; | |
1da177e4 LT |
331 | } |
332 | ||
74451e66 DB |
333 | /* See if it's in a module or a BPF JITed image. */ |
334 | ret = module_address_lookup(addr, symbolsize, offset, | |
9294523e | 335 | modname, modbuildid, namebuf); |
74451e66 DB |
336 | if (!ret) |
337 | ret = bpf_address_lookup(addr, symbolsize, | |
338 | offset, modname, namebuf); | |
aba4b5c2 SRV |
339 | |
340 | if (!ret) | |
341 | ret = ftrace_mod_address_lookup(addr, symbolsize, | |
342 | offset, modname, namebuf); | |
8b8e6b5d ST |
343 | |
344 | found: | |
345 | cleanup_symbol_name(namebuf); | |
74451e66 | 346 | return ret; |
1da177e4 LT |
347 | } |
348 | ||
9294523e SB |
349 | /* |
350 | * Lookup an address | |
351 | * - modname is set to NULL if it's in the kernel. | |
352 | * - We guarantee that the returned name is valid until we reschedule even if. | |
353 | * It resides in a module. | |
354 | * - We also guarantee that modname will be valid until rescheduled. | |
355 | */ | |
356 | const char *kallsyms_lookup(unsigned long addr, | |
357 | unsigned long *symbolsize, | |
358 | unsigned long *offset, | |
359 | char **modname, char *namebuf) | |
360 | { | |
361 | return kallsyms_lookup_buildid(addr, symbolsize, offset, modname, | |
362 | NULL, namebuf); | |
363 | } | |
364 | ||
9d65cb4a AD |
365 | int lookup_symbol_name(unsigned long addr, char *symname) |
366 | { | |
8b8e6b5d ST |
367 | int res; |
368 | ||
9d65cb4a | 369 | symname[0] = '\0'; |
9281acea | 370 | symname[KSYM_NAME_LEN - 1] = '\0'; |
9d65cb4a AD |
371 | |
372 | if (is_ksym_addr(addr)) { | |
373 | unsigned long pos; | |
374 | ||
375 | pos = get_symbol_pos(addr, NULL, NULL); | |
376 | /* Grab name */ | |
e3f26752 CG |
377 | kallsyms_expand_symbol(get_symbol_offset(pos), |
378 | symname, KSYM_NAME_LEN); | |
8b8e6b5d | 379 | goto found; |
9d65cb4a | 380 | } |
ad6ccfad | 381 | /* See if it's in a module. */ |
8b8e6b5d ST |
382 | res = lookup_module_symbol_name(addr, symname); |
383 | if (res) | |
384 | return res; | |
385 | ||
386 | found: | |
387 | cleanup_symbol_name(symname); | |
388 | return 0; | |
9d65cb4a AD |
389 | } |
390 | ||
a5c43dae AD |
391 | int lookup_symbol_attrs(unsigned long addr, unsigned long *size, |
392 | unsigned long *offset, char *modname, char *name) | |
393 | { | |
8b8e6b5d ST |
394 | int res; |
395 | ||
a5c43dae | 396 | name[0] = '\0'; |
9281acea | 397 | name[KSYM_NAME_LEN - 1] = '\0'; |
a5c43dae AD |
398 | |
399 | if (is_ksym_addr(addr)) { | |
400 | unsigned long pos; | |
401 | ||
402 | pos = get_symbol_pos(addr, size, offset); | |
403 | /* Grab name */ | |
e3f26752 CG |
404 | kallsyms_expand_symbol(get_symbol_offset(pos), |
405 | name, KSYM_NAME_LEN); | |
a5c43dae | 406 | modname[0] = '\0'; |
8b8e6b5d | 407 | goto found; |
a5c43dae | 408 | } |
ad6ccfad | 409 | /* See if it's in a module. */ |
8b8e6b5d ST |
410 | res = lookup_module_symbol_attrs(addr, size, offset, modname, name); |
411 | if (res) | |
412 | return res; | |
413 | ||
414 | found: | |
415 | cleanup_symbol_name(name); | |
416 | return 0; | |
a5c43dae AD |
417 | } |
418 | ||
42e38083 | 419 | /* Look up a kernel symbol and return it in a text buffer. */ |
0f77a8d3 | 420 | static int __sprint_symbol(char *buffer, unsigned long address, |
9294523e | 421 | int symbol_offset, int add_offset, int add_buildid) |
1da177e4 LT |
422 | { |
423 | char *modname; | |
9294523e | 424 | const unsigned char *buildid; |
1da177e4 LT |
425 | const char *name; |
426 | unsigned long offset, size; | |
966c8c12 | 427 | int len; |
1da177e4 | 428 | |
0f77a8d3 | 429 | address += symbol_offset; |
9294523e SB |
430 | name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid, |
431 | buffer); | |
1da177e4 | 432 | if (!name) |
b86280aa | 433 | return sprintf(buffer, "0x%lx", address - symbol_offset); |
19769b76 | 434 | |
966c8c12 HD |
435 | if (name != buffer) |
436 | strcpy(buffer, name); | |
437 | len = strlen(buffer); | |
0f77a8d3 | 438 | offset -= symbol_offset; |
966c8c12 | 439 | |
4796dd20 SB |
440 | if (add_offset) |
441 | len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); | |
442 | ||
9294523e SB |
443 | if (modname) { |
444 | len += sprintf(buffer + len, " [%s", modname); | |
445 | #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) | |
446 | if (add_buildid && buildid) { | |
447 | /* build ID should match length of sprintf */ | |
448 | #if IS_ENABLED(CONFIG_MODULES) | |
449 | static_assert(sizeof(typeof_member(struct module, build_id)) == 20); | |
450 | #endif | |
451 | len += sprintf(buffer + len, " %20phN", buildid); | |
452 | } | |
453 | #endif | |
454 | len += sprintf(buffer + len, "]"); | |
455 | } | |
966c8c12 HD |
456 | |
457 | return len; | |
42e38083 | 458 | } |
0f77a8d3 NK |
459 | |
460 | /** | |
461 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer | |
462 | * @buffer: buffer to be stored | |
463 | * @address: address to lookup | |
464 | * | |
465 | * This function looks up a kernel symbol with @address and stores its name, | |
466 | * offset, size and module name to @buffer if possible. If no symbol was found, | |
467 | * just saves its @address as is. | |
468 | * | |
469 | * This function returns the number of bytes stored in @buffer. | |
470 | */ | |
471 | int sprint_symbol(char *buffer, unsigned long address) | |
472 | { | |
9294523e | 473 | return __sprint_symbol(buffer, address, 0, 1, 0); |
0f77a8d3 | 474 | } |
ad6ccfad | 475 | EXPORT_SYMBOL_GPL(sprint_symbol); |
42e38083 | 476 | |
9294523e SB |
477 | /** |
478 | * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer | |
479 | * @buffer: buffer to be stored | |
480 | * @address: address to lookup | |
481 | * | |
482 | * This function looks up a kernel symbol with @address and stores its name, | |
483 | * offset, size, module name and module build ID to @buffer if possible. If no | |
484 | * symbol was found, just saves its @address as is. | |
485 | * | |
486 | * This function returns the number of bytes stored in @buffer. | |
487 | */ | |
488 | int sprint_symbol_build_id(char *buffer, unsigned long address) | |
489 | { | |
490 | return __sprint_symbol(buffer, address, 0, 1, 1); | |
491 | } | |
492 | EXPORT_SYMBOL_GPL(sprint_symbol_build_id); | |
493 | ||
4796dd20 SB |
494 | /** |
495 | * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer | |
496 | * @buffer: buffer to be stored | |
497 | * @address: address to lookup | |
498 | * | |
499 | * This function looks up a kernel symbol with @address and stores its name | |
500 | * and module name to @buffer if possible. If no symbol was found, just saves | |
501 | * its @address as is. | |
502 | * | |
503 | * This function returns the number of bytes stored in @buffer. | |
504 | */ | |
505 | int sprint_symbol_no_offset(char *buffer, unsigned long address) | |
506 | { | |
9294523e | 507 | return __sprint_symbol(buffer, address, 0, 0, 0); |
4796dd20 SB |
508 | } |
509 | EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); | |
510 | ||
0f77a8d3 NK |
511 | /** |
512 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer | |
513 | * @buffer: buffer to be stored | |
514 | * @address: address to lookup | |
515 | * | |
516 | * This function is for stack backtrace and does the same thing as | |
517 | * sprint_symbol() but with modified/decreased @address. If there is a | |
518 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
519 | * the call so that the stack-saved return address could point outside of the | |
520 | * caller. This function ensures that kallsyms will find the original caller | |
521 | * by decreasing @address. | |
522 | * | |
523 | * This function returns the number of bytes stored in @buffer. | |
524 | */ | |
525 | int sprint_backtrace(char *buffer, unsigned long address) | |
526 | { | |
9294523e SB |
527 | return __sprint_symbol(buffer, address, -1, 1, 0); |
528 | } | |
529 | ||
530 | /** | |
531 | * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer | |
532 | * @buffer: buffer to be stored | |
533 | * @address: address to lookup | |
534 | * | |
535 | * This function is for stack backtrace and does the same thing as | |
536 | * sprint_symbol() but with modified/decreased @address. If there is a | |
537 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
538 | * the call so that the stack-saved return address could point outside of the | |
539 | * caller. This function ensures that kallsyms will find the original caller | |
540 | * by decreasing @address. This function also appends the module build ID to | |
541 | * the @buffer if @address is within a kernel module. | |
542 | * | |
543 | * This function returns the number of bytes stored in @buffer. | |
544 | */ | |
545 | int sprint_backtrace_build_id(char *buffer, unsigned long address) | |
546 | { | |
547 | return __sprint_symbol(buffer, address, -1, 1, 1); | |
0f77a8d3 NK |
548 | } |
549 | ||
1da177e4 | 550 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ |
ad6ccfad | 551 | struct kallsym_iter { |
1da177e4 | 552 | loff_t pos; |
d83212d5 | 553 | loff_t pos_arch_end; |
74451e66 | 554 | loff_t pos_mod_end; |
6171a031 | 555 | loff_t pos_ftrace_mod_end; |
d002b8bc | 556 | loff_t pos_bpf_end; |
1da177e4 | 557 | unsigned long value; |
ad6ccfad | 558 | unsigned int nameoff; /* If iterating in core kernel symbols. */ |
1da177e4 | 559 | char type; |
9281acea TH |
560 | char name[KSYM_NAME_LEN]; |
561 | char module_name[MODULE_NAME_LEN]; | |
ea07890a | 562 | int exported; |
c0f3ea15 | 563 | int show_value; |
1da177e4 LT |
564 | }; |
565 | ||
d83212d5 AS |
566 | int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value, |
567 | char *type, char *name) | |
568 | { | |
569 | return -EINVAL; | |
570 | } | |
571 | ||
572 | static int get_ksymbol_arch(struct kallsym_iter *iter) | |
573 | { | |
574 | int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms, | |
575 | &iter->value, &iter->type, | |
576 | iter->name); | |
577 | ||
578 | if (ret < 0) { | |
579 | iter->pos_arch_end = iter->pos; | |
580 | return 0; | |
581 | } | |
582 | ||
583 | return 1; | |
584 | } | |
585 | ||
1da177e4 LT |
586 | static int get_ksymbol_mod(struct kallsym_iter *iter) |
587 | { | |
d83212d5 | 588 | int ret = module_get_kallsym(iter->pos - iter->pos_arch_end, |
74451e66 DB |
589 | &iter->value, &iter->type, |
590 | iter->name, iter->module_name, | |
591 | &iter->exported); | |
592 | if (ret < 0) { | |
593 | iter->pos_mod_end = iter->pos; | |
1da177e4 | 594 | return 0; |
74451e66 DB |
595 | } |
596 | ||
1da177e4 LT |
597 | return 1; |
598 | } | |
599 | ||
fc0ea795 AH |
600 | /* |
601 | * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace | |
602 | * purposes. In that case "__builtin__ftrace" is used as a module name, even | |
603 | * though "__builtin__ftrace" is not a module. | |
604 | */ | |
6171a031 SRV |
605 | static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter) |
606 | { | |
607 | int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end, | |
608 | &iter->value, &iter->type, | |
609 | iter->name, iter->module_name, | |
610 | &iter->exported); | |
611 | if (ret < 0) { | |
612 | iter->pos_ftrace_mod_end = iter->pos; | |
613 | return 0; | |
614 | } | |
615 | ||
616 | return 1; | |
617 | } | |
618 | ||
74451e66 DB |
619 | static int get_ksymbol_bpf(struct kallsym_iter *iter) |
620 | { | |
d002b8bc AH |
621 | int ret; |
622 | ||
6934058d | 623 | strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN); |
74451e66 | 624 | iter->exported = 0; |
d002b8bc AH |
625 | ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end, |
626 | &iter->value, &iter->type, | |
627 | iter->name); | |
628 | if (ret < 0) { | |
629 | iter->pos_bpf_end = iter->pos; | |
630 | return 0; | |
631 | } | |
632 | ||
633 | return 1; | |
634 | } | |
635 | ||
636 | /* | |
637 | * This uses "__builtin__kprobes" as a module name for symbols for pages | |
638 | * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a | |
639 | * module. | |
640 | */ | |
641 | static int get_ksymbol_kprobe(struct kallsym_iter *iter) | |
642 | { | |
643 | strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN); | |
644 | iter->exported = 0; | |
645 | return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end, | |
646 | &iter->value, &iter->type, | |
647 | iter->name) < 0 ? 0 : 1; | |
74451e66 DB |
648 | } |
649 | ||
1da177e4 LT |
650 | /* Returns space to next name. */ |
651 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
652 | { | |
653 | unsigned off = iter->nameoff; | |
654 | ||
ea07890a | 655 | iter->module_name[0] = '\0'; |
2213e9a6 | 656 | iter->value = kallsyms_sym_address(iter->pos); |
1da177e4 LT |
657 | |
658 | iter->type = kallsyms_get_symbol_type(off); | |
659 | ||
e3f26752 | 660 | off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name)); |
1da177e4 LT |
661 | |
662 | return off - iter->nameoff; | |
663 | } | |
664 | ||
665 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
666 | { | |
667 | iter->name[0] = '\0'; | |
668 | iter->nameoff = get_symbol_offset(new_pos); | |
669 | iter->pos = new_pos; | |
6171a031 | 670 | if (new_pos == 0) { |
d83212d5 | 671 | iter->pos_arch_end = 0; |
74451e66 | 672 | iter->pos_mod_end = 0; |
6171a031 | 673 | iter->pos_ftrace_mod_end = 0; |
d002b8bc | 674 | iter->pos_bpf_end = 0; |
6171a031 | 675 | } |
74451e66 DB |
676 | } |
677 | ||
b9667942 AH |
678 | /* |
679 | * The end position (last + 1) of each additional kallsyms section is recorded | |
680 | * in iter->pos_..._end as each section is added, and so can be used to | |
681 | * determine which get_ksymbol_...() function to call next. | |
682 | */ | |
74451e66 DB |
683 | static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) |
684 | { | |
685 | iter->pos = pos; | |
686 | ||
d83212d5 AS |
687 | if ((!iter->pos_arch_end || iter->pos_arch_end > pos) && |
688 | get_ksymbol_arch(iter)) | |
689 | return 1; | |
690 | ||
b9667942 AH |
691 | if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && |
692 | get_ksymbol_mod(iter)) | |
6171a031 | 693 | return 1; |
6171a031 | 694 | |
b9667942 AH |
695 | if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) && |
696 | get_ksymbol_ftrace_mod(iter)) | |
697 | return 1; | |
74451e66 | 698 | |
d002b8bc AH |
699 | if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) && |
700 | get_ksymbol_bpf(iter)) | |
701 | return 1; | |
702 | ||
703 | return get_ksymbol_kprobe(iter); | |
1da177e4 LT |
704 | } |
705 | ||
706 | /* Returns false if pos at or past end of file. */ | |
707 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
708 | { | |
709 | /* Module symbols can be accessed randomly. */ | |
74451e66 DB |
710 | if (pos >= kallsyms_num_syms) |
711 | return update_iter_mod(iter, pos); | |
ad6ccfad | 712 | |
1da177e4 LT |
713 | /* If we're not on the desired position, reset to new position. */ |
714 | if (pos != iter->pos) | |
715 | reset_iter(iter, pos); | |
716 | ||
717 | iter->nameoff += get_ksymbol_core(iter); | |
718 | iter->pos++; | |
719 | ||
720 | return 1; | |
721 | } | |
722 | ||
723 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
724 | { | |
725 | (*pos)++; | |
726 | ||
727 | if (!update_iter(m->private, *pos)) | |
728 | return NULL; | |
729 | return p; | |
730 | } | |
731 | ||
732 | static void *s_start(struct seq_file *m, loff_t *pos) | |
733 | { | |
734 | if (!update_iter(m->private, *pos)) | |
735 | return NULL; | |
736 | return m->private; | |
737 | } | |
738 | ||
739 | static void s_stop(struct seq_file *m, void *p) | |
740 | { | |
741 | } | |
742 | ||
743 | static int s_show(struct seq_file *m, void *p) | |
744 | { | |
668533dc | 745 | void *value; |
1da177e4 LT |
746 | struct kallsym_iter *iter = m->private; |
747 | ||
ad6ccfad | 748 | /* Some debugging symbols have no name. Ignore them. */ |
1da177e4 LT |
749 | if (!iter->name[0]) |
750 | return 0; | |
751 | ||
668533dc | 752 | value = iter->show_value ? (void *)iter->value : NULL; |
c0f3ea15 | 753 | |
ea07890a AD |
754 | if (iter->module_name[0]) { |
755 | char type; | |
756 | ||
ad6ccfad MK |
757 | /* |
758 | * Label it "global" if it is exported, | |
759 | * "local" if not exported. | |
760 | */ | |
ea07890a AD |
761 | type = iter->exported ? toupper(iter->type) : |
762 | tolower(iter->type); | |
668533dc | 763 | seq_printf(m, "%px %c %s\t[%s]\n", value, |
9f36e2c4 | 764 | type, iter->name, iter->module_name); |
ea07890a | 765 | } else |
668533dc | 766 | seq_printf(m, "%px %c %s\n", value, |
9f36e2c4 | 767 | iter->type, iter->name); |
1da177e4 LT |
768 | return 0; |
769 | } | |
770 | ||
15ad7cdc | 771 | static const struct seq_operations kallsyms_op = { |
1da177e4 LT |
772 | .start = s_start, |
773 | .next = s_next, | |
774 | .stop = s_stop, | |
775 | .show = s_show | |
776 | }; | |
777 | ||
c0f3ea15 LT |
778 | static inline int kallsyms_for_perf(void) |
779 | { | |
780 | #ifdef CONFIG_PERF_EVENTS | |
781 | extern int sysctl_perf_event_paranoid; | |
782 | if (sysctl_perf_event_paranoid <= 1) | |
783 | return 1; | |
784 | #endif | |
785 | return 0; | |
786 | } | |
787 | ||
788 | /* | |
789 | * We show kallsyms information even to normal users if we've enabled | |
790 | * kernel profiling and are explicitly not paranoid (so kptr_restrict | |
791 | * is clear, and sysctl_perf_event_paranoid isn't set). | |
792 | * | |
793 | * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to | |
794 | * block even that). | |
795 | */ | |
16025184 | 796 | bool kallsyms_show_value(const struct cred *cred) |
c0f3ea15 LT |
797 | { |
798 | switch (kptr_restrict) { | |
799 | case 0: | |
800 | if (kallsyms_for_perf()) | |
16025184 | 801 | return true; |
df561f66 | 802 | fallthrough; |
c0f3ea15 | 803 | case 1: |
16025184 KC |
804 | if (security_capable(cred, &init_user_ns, CAP_SYSLOG, |
805 | CAP_OPT_NOAUDIT) == 0) | |
806 | return true; | |
df561f66 | 807 | fallthrough; |
c0f3ea15 | 808 | default: |
16025184 | 809 | return false; |
c0f3ea15 LT |
810 | } |
811 | } | |
812 | ||
1da177e4 LT |
813 | static int kallsyms_open(struct inode *inode, struct file *file) |
814 | { | |
ad6ccfad MK |
815 | /* |
816 | * We keep iterator in m->private, since normal case is to | |
1da177e4 | 817 | * s_start from where we left off, so we avoid doing |
ad6ccfad MK |
818 | * using get_symbol_offset for every symbol. |
819 | */ | |
1da177e4 | 820 | struct kallsym_iter *iter; |
0049f26a | 821 | iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter)); |
1da177e4 LT |
822 | if (!iter) |
823 | return -ENOMEM; | |
824 | reset_iter(iter, 0); | |
825 | ||
16025184 KC |
826 | /* |
827 | * Instead of checking this on every s_show() call, cache | |
828 | * the result here at open time. | |
829 | */ | |
830 | iter->show_value = kallsyms_show_value(file->f_cred); | |
0049f26a | 831 | return 0; |
1da177e4 LT |
832 | } |
833 | ||
67fc4e0c JW |
834 | #ifdef CONFIG_KGDB_KDB |
835 | const char *kdb_walk_kallsyms(loff_t *pos) | |
836 | { | |
837 | static struct kallsym_iter kdb_walk_kallsyms_iter; | |
838 | if (*pos == 0) { | |
839 | memset(&kdb_walk_kallsyms_iter, 0, | |
840 | sizeof(kdb_walk_kallsyms_iter)); | |
841 | reset_iter(&kdb_walk_kallsyms_iter, 0); | |
842 | } | |
843 | while (1) { | |
844 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) | |
845 | return NULL; | |
846 | ++*pos; | |
847 | /* Some debugging symbols have no name. Ignore them. */ | |
848 | if (kdb_walk_kallsyms_iter.name[0]) | |
849 | return kdb_walk_kallsyms_iter.name; | |
850 | } | |
851 | } | |
852 | #endif /* CONFIG_KGDB_KDB */ | |
853 | ||
97a32539 AD |
854 | static const struct proc_ops kallsyms_proc_ops = { |
855 | .proc_open = kallsyms_open, | |
856 | .proc_read = seq_read, | |
857 | .proc_lseek = seq_lseek, | |
858 | .proc_release = seq_release_private, | |
1da177e4 LT |
859 | }; |
860 | ||
861 | static int __init kallsyms_init(void) | |
862 | { | |
97a32539 | 863 | proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops); |
1da177e4 LT |
864 | return 0; |
865 | } | |
ad6ccfad | 866 | device_initcall(kallsyms_init); |