Commit | Line | Data |
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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> | |
bed0d9a5 | 32 | #include <linux/bsearch.h> |
647cafa2 | 33 | #include <linux/btf_ids.h> |
1da177e4 | 34 | |
71f8c155 | 35 | #include "kallsyms_internal.h" |
1da177e4 | 36 | |
ad6ccfad MK |
37 | /* |
38 | * Expand a compressed symbol data into the resulting uncompressed string, | |
e3f26752 | 39 | * if uncompressed string is too long (>= maxlen), it will be truncated, |
ad6ccfad MK |
40 | * given the offset to where the symbol is in the compressed stream. |
41 | */ | |
e3f26752 CG |
42 | static unsigned int kallsyms_expand_symbol(unsigned int off, |
43 | char *result, size_t maxlen) | |
1da177e4 LT |
44 | { |
45 | int len, skipped_first = 0; | |
cde26a6e MY |
46 | const char *tptr; |
47 | const u8 *data; | |
1da177e4 | 48 | |
ad6ccfad | 49 | /* Get the compressed symbol length from the first symbol byte. */ |
1da177e4 LT |
50 | data = &kallsyms_names[off]; |
51 | len = *data; | |
52 | data++; | |
73bbb944 MO |
53 | off++; |
54 | ||
55 | /* If MSB is 1, it is a "big" symbol, so needs an additional byte. */ | |
56 | if ((len & 0x80) != 0) { | |
57 | len = (len & 0x7F) | (*data << 7); | |
58 | data++; | |
59 | off++; | |
60 | } | |
1da177e4 | 61 | |
ad6ccfad MK |
62 | /* |
63 | * Update the offset to return the offset for the next symbol on | |
64 | * the compressed stream. | |
65 | */ | |
73bbb944 | 66 | off += len; |
1da177e4 | 67 | |
ad6ccfad MK |
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]]; | |
1da177e4 LT |
74 | data++; |
75 | len--; | |
76 | ||
77 | while (*tptr) { | |
ad6ccfad | 78 | if (skipped_first) { |
e3f26752 CG |
79 | if (maxlen <= 1) |
80 | goto tail; | |
1da177e4 LT |
81 | *result = *tptr; |
82 | result++; | |
e3f26752 | 83 | maxlen--; |
1da177e4 LT |
84 | } else |
85 | skipped_first = 1; | |
86 | tptr++; | |
87 | } | |
88 | } | |
89 | ||
e3f26752 CG |
90 | tail: |
91 | if (maxlen) | |
92 | *result = '\0'; | |
1da177e4 | 93 | |
ad6ccfad | 94 | /* Return to offset to the next symbol. */ |
1da177e4 LT |
95 | return off; |
96 | } | |
97 | ||
ad6ccfad MK |
98 | /* |
99 | * Get symbol type information. This is encoded as a single char at the | |
100 | * beginning of the symbol name. | |
101 | */ | |
1da177e4 LT |
102 | static char kallsyms_get_symbol_type(unsigned int off) |
103 | { | |
ad6ccfad MK |
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]]]; | |
1da177e4 LT |
109 | } |
110 | ||
111 | ||
ad6ccfad MK |
112 | /* |
113 | * Find the offset on the compressed stream given and index in the | |
114 | * kallsyms array. | |
115 | */ | |
1da177e4 LT |
116 | static unsigned int get_symbol_offset(unsigned long pos) |
117 | { | |
aad09470 | 118 | const u8 *name; |
73bbb944 | 119 | int i, len; |
1da177e4 | 120 | |
ad6ccfad MK |
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]]; | |
1da177e4 | 126 | |
ad6ccfad MK |
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 | */ | |
73bbb944 MO |
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 | } | |
1da177e4 LT |
145 | |
146 | return name - kallsyms_names; | |
147 | } | |
148 | ||
30f3bb09 | 149 | unsigned long kallsyms_sym_address(int idx) |
2213e9a6 AB |
150 | { |
151 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) | |
152 | return kallsyms_addresses[idx]; | |
153 | ||
154 | /* values are unsigned offsets if --absolute-percpu is not in effect */ | |
155 | if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU)) | |
156 | return kallsyms_relative_base + (u32)kallsyms_offsets[idx]; | |
157 | ||
158 | /* ...otherwise, positive offsets are absolute values */ | |
159 | if (kallsyms_offsets[idx] >= 0) | |
160 | return kallsyms_offsets[idx]; | |
161 | ||
162 | /* ...and negative offsets are relative to kallsyms_relative_base - 1 */ | |
163 | return kallsyms_relative_base - 1 - kallsyms_offsets[idx]; | |
164 | } | |
165 | ||
76903a96 | 166 | static void cleanup_symbol_name(char *s) |
8b8e6b5d ST |
167 | { |
168 | char *res; | |
169 | ||
6eb4bd92 | 170 | if (!IS_ENABLED(CONFIG_LTO_CLANG)) |
76903a96 | 171 | return; |
6eb4bd92 ND |
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 | |
8cc32a9b | 177 | * character in an identifier in C. Suffixes only in LLVM LTO observed: |
6eb4bd92 | 178 | * - foo.llvm.[0-9a-f]+ |
6eb4bd92 | 179 | */ |
8cc32a9b | 180 | res = strstr(s, ".llvm."); |
76903a96 | 181 | if (res) |
6eb4bd92 | 182 | *res = '\0'; |
6eb4bd92 | 183 | |
76903a96 | 184 | return; |
8b8e6b5d | 185 | } |
8b8e6b5d | 186 | |
60443c88 ZL |
187 | static int compare_symbol_name(const char *name, char *namebuf) |
188 | { | |
33f0467f YS |
189 | /* The kallsyms_seqs_of_names is sorted based on names after |
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); | |
60443c88 ZL |
196 | } |
197 | ||
19bd8981 ZL |
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 | ||
60443c88 ZL |
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; | |
19bd8981 | 222 | seq = get_symbol_seq(mid); |
60443c88 ZL |
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) { | |
19bd8981 | 239 | seq = get_symbol_seq(low - 1); |
60443c88 ZL |
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) { | |
19bd8981 | 251 | seq = get_symbol_seq(high + 1); |
60443c88 ZL |
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 | ||
1da177e4 LT |
264 | /* Lookup the address for this symbol. Returns 0 if not found. */ |
265 | unsigned long kallsyms_lookup_name(const char *name) | |
266 | { | |
60443c88 ZL |
267 | int ret; |
268 | unsigned int i; | |
1da177e4 | 269 | |
aecf489f JO |
270 | /* Skip the search for empty string. */ |
271 | if (!*name) | |
272 | return 0; | |
273 | ||
60443c88 ZL |
274 | ret = kallsyms_lookup_names(name, &i, NULL); |
275 | if (!ret) | |
19bd8981 | 276 | return kallsyms_sym_address(get_symbol_seq(i)); |
8b8e6b5d | 277 | |
1da177e4 LT |
278 | return module_kallsyms_lookup_name(name); |
279 | } | |
1da177e4 | 280 | |
013c1667 CH |
281 | /* |
282 | * Iterate over all symbols in vmlinux. For symbols from modules use | |
283 | * module_kallsyms_on_each_symbol instead. | |
284 | */ | |
3703bd54 | 285 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long), |
75a66614 AK |
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++) { | |
e3f26752 | 294 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
3703bd54 | 295 | ret = fn(data, namebuf, kallsyms_sym_address(i)); |
75a66614 AK |
296 | if (ret != 0) |
297 | return ret; | |
f5bdb34b | 298 | cond_resched(); |
75a66614 | 299 | } |
013c1667 | 300 | return 0; |
75a66614 | 301 | } |
75a66614 | 302 | |
4dc533e0 ZL |
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 | ||
ffc50891 FBH |
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 | ||
ad6ccfad | 328 | /* Do a binary search on the sorted kallsyms_addresses array. */ |
ffc50891 FBH |
329 | low = 0; |
330 | high = kallsyms_num_syms; | |
331 | ||
332 | while (high - low > 1) { | |
2fc9c4e1 | 333 | mid = low + (high - low) / 2; |
2213e9a6 | 334 | if (kallsyms_sym_address(mid) <= addr) |
ffc50891 FBH |
335 | low = mid; |
336 | else | |
337 | high = mid; | |
338 | } | |
339 | ||
340 | /* | |
ad6ccfad MK |
341 | * Search for the first aliased symbol. Aliased |
342 | * symbols are symbols with the same address. | |
ffc50891 | 343 | */ |
2213e9a6 | 344 | while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low)) |
ffc50891 FBH |
345 | --low; |
346 | ||
2213e9a6 | 347 | symbol_start = kallsyms_sym_address(low); |
ffc50891 | 348 | |
ad6ccfad | 349 | /* Search for next non-aliased symbol. */ |
ffc50891 | 350 | for (i = low + 1; i < kallsyms_num_syms; i++) { |
2213e9a6 AB |
351 | if (kallsyms_sym_address(i) > symbol_start) { |
352 | symbol_end = kallsyms_sym_address(i); | |
ffc50891 FBH |
353 | break; |
354 | } | |
355 | } | |
356 | ||
ad6ccfad | 357 | /* If we found no next symbol, we use the end of the section. */ |
ffc50891 FBH |
358 | if (!symbol_end) { |
359 | if (is_kernel_inittext(addr)) | |
360 | symbol_end = (unsigned long)_einittext; | |
63b23e2c | 361 | else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) |
ffc50891 FBH |
362 | symbol_end = (unsigned long)_end; |
363 | else | |
364 | symbol_end = (unsigned long)_etext; | |
365 | } | |
366 | ||
ffb45122 AD |
367 | if (symbolsize) |
368 | *symbolsize = symbol_end - symbol_start; | |
369 | if (offset) | |
370 | *offset = addr - symbol_start; | |
ffc50891 FBH |
371 | |
372 | return low; | |
373 | } | |
374 | ||
375 | /* | |
376 | * Lookup an address but don't bother to find any names. | |
377 | */ | |
378 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, | |
379 | unsigned long *offset) | |
380 | { | |
6dd06c9f | 381 | char namebuf[KSYM_NAME_LEN]; |
74451e66 | 382 | |
2a1a3fa0 MZ |
383 | if (is_ksym_addr(addr)) { |
384 | get_symbol_pos(addr, symbolsize, offset); | |
385 | return 1; | |
386 | } | |
9294523e | 387 | return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) || |
74451e66 | 388 | !!__bpf_address_lookup(addr, symbolsize, offset, namebuf); |
ffc50891 FBH |
389 | } |
390 | ||
9294523e SB |
391 | static const char *kallsyms_lookup_buildid(unsigned long addr, |
392 | unsigned long *symbolsize, | |
393 | unsigned long *offset, char **modname, | |
394 | const unsigned char **modbuildid, char *namebuf) | |
1da177e4 | 395 | { |
74451e66 DB |
396 | const char *ret; |
397 | ||
9281acea | 398 | namebuf[KSYM_NAME_LEN - 1] = 0; |
1da177e4 LT |
399 | namebuf[0] = 0; |
400 | ||
ffc50891 FBH |
401 | if (is_ksym_addr(addr)) { |
402 | unsigned long pos; | |
1da177e4 | 403 | |
ffc50891 | 404 | pos = get_symbol_pos(addr, symbolsize, offset); |
1da177e4 | 405 | /* Grab name */ |
e3f26752 CG |
406 | kallsyms_expand_symbol(get_symbol_offset(pos), |
407 | namebuf, KSYM_NAME_LEN); | |
7a74fc49 KM |
408 | if (modname) |
409 | *modname = NULL; | |
9294523e SB |
410 | if (modbuildid) |
411 | *modbuildid = NULL; | |
8b8e6b5d ST |
412 | |
413 | ret = namebuf; | |
414 | goto found; | |
1da177e4 LT |
415 | } |
416 | ||
74451e66 DB |
417 | /* See if it's in a module or a BPF JITed image. */ |
418 | ret = module_address_lookup(addr, symbolsize, offset, | |
9294523e | 419 | modname, modbuildid, namebuf); |
74451e66 DB |
420 | if (!ret) |
421 | ret = bpf_address_lookup(addr, symbolsize, | |
422 | offset, modname, namebuf); | |
aba4b5c2 SRV |
423 | |
424 | if (!ret) | |
425 | ret = ftrace_mod_address_lookup(addr, symbolsize, | |
426 | offset, modname, namebuf); | |
8b8e6b5d ST |
427 | |
428 | found: | |
429 | cleanup_symbol_name(namebuf); | |
74451e66 | 430 | return ret; |
1da177e4 LT |
431 | } |
432 | ||
9294523e SB |
433 | /* |
434 | * Lookup an address | |
435 | * - modname is set to NULL if it's in the kernel. | |
436 | * - We guarantee that the returned name is valid until we reschedule even if. | |
437 | * It resides in a module. | |
438 | * - We also guarantee that modname will be valid until rescheduled. | |
439 | */ | |
440 | const char *kallsyms_lookup(unsigned long addr, | |
441 | unsigned long *symbolsize, | |
442 | unsigned long *offset, | |
443 | char **modname, char *namebuf) | |
444 | { | |
445 | return kallsyms_lookup_buildid(addr, symbolsize, offset, modname, | |
446 | NULL, namebuf); | |
447 | } | |
448 | ||
9d65cb4a AD |
449 | int lookup_symbol_name(unsigned long addr, char *symname) |
450 | { | |
8b8e6b5d ST |
451 | int res; |
452 | ||
9d65cb4a | 453 | symname[0] = '\0'; |
9281acea | 454 | symname[KSYM_NAME_LEN - 1] = '\0'; |
9d65cb4a AD |
455 | |
456 | if (is_ksym_addr(addr)) { | |
457 | unsigned long pos; | |
458 | ||
459 | pos = get_symbol_pos(addr, NULL, NULL); | |
460 | /* Grab name */ | |
e3f26752 CG |
461 | kallsyms_expand_symbol(get_symbol_offset(pos), |
462 | symname, KSYM_NAME_LEN); | |
8b8e6b5d | 463 | goto found; |
9d65cb4a | 464 | } |
ad6ccfad | 465 | /* See if it's in a module. */ |
8b8e6b5d ST |
466 | res = lookup_module_symbol_name(addr, symname); |
467 | if (res) | |
468 | return res; | |
469 | ||
470 | found: | |
471 | cleanup_symbol_name(symname); | |
472 | return 0; | |
9d65cb4a AD |
473 | } |
474 | ||
42e38083 | 475 | /* Look up a kernel symbol and return it in a text buffer. */ |
0f77a8d3 | 476 | static int __sprint_symbol(char *buffer, unsigned long address, |
9294523e | 477 | int symbol_offset, int add_offset, int add_buildid) |
1da177e4 LT |
478 | { |
479 | char *modname; | |
9294523e | 480 | const unsigned char *buildid; |
1da177e4 LT |
481 | const char *name; |
482 | unsigned long offset, size; | |
966c8c12 | 483 | int len; |
1da177e4 | 484 | |
0f77a8d3 | 485 | address += symbol_offset; |
9294523e SB |
486 | name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid, |
487 | buffer); | |
1da177e4 | 488 | if (!name) |
b86280aa | 489 | return sprintf(buffer, "0x%lx", address - symbol_offset); |
19769b76 | 490 | |
966c8c12 HD |
491 | if (name != buffer) |
492 | strcpy(buffer, name); | |
493 | len = strlen(buffer); | |
0f77a8d3 | 494 | offset -= symbol_offset; |
966c8c12 | 495 | |
4796dd20 SB |
496 | if (add_offset) |
497 | len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); | |
498 | ||
9294523e SB |
499 | if (modname) { |
500 | len += sprintf(buffer + len, " [%s", modname); | |
501 | #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) | |
502 | if (add_buildid && buildid) { | |
503 | /* build ID should match length of sprintf */ | |
504 | #if IS_ENABLED(CONFIG_MODULES) | |
505 | static_assert(sizeof(typeof_member(struct module, build_id)) == 20); | |
506 | #endif | |
507 | len += sprintf(buffer + len, " %20phN", buildid); | |
508 | } | |
509 | #endif | |
510 | len += sprintf(buffer + len, "]"); | |
511 | } | |
966c8c12 HD |
512 | |
513 | return len; | |
42e38083 | 514 | } |
0f77a8d3 NK |
515 | |
516 | /** | |
517 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer | |
518 | * @buffer: buffer to be stored | |
519 | * @address: address to lookup | |
520 | * | |
521 | * This function looks up a kernel symbol with @address and stores its name, | |
522 | * offset, size and module name to @buffer if possible. If no symbol was found, | |
523 | * just saves its @address as is. | |
524 | * | |
525 | * This function returns the number of bytes stored in @buffer. | |
526 | */ | |
527 | int sprint_symbol(char *buffer, unsigned long address) | |
528 | { | |
9294523e | 529 | return __sprint_symbol(buffer, address, 0, 1, 0); |
0f77a8d3 | 530 | } |
ad6ccfad | 531 | EXPORT_SYMBOL_GPL(sprint_symbol); |
42e38083 | 532 | |
9294523e SB |
533 | /** |
534 | * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer | |
535 | * @buffer: buffer to be stored | |
536 | * @address: address to lookup | |
537 | * | |
538 | * This function looks up a kernel symbol with @address and stores its name, | |
539 | * offset, size, module name and module build ID to @buffer if possible. If no | |
540 | * symbol was found, just saves its @address as is. | |
541 | * | |
542 | * This function returns the number of bytes stored in @buffer. | |
543 | */ | |
544 | int sprint_symbol_build_id(char *buffer, unsigned long address) | |
545 | { | |
546 | return __sprint_symbol(buffer, address, 0, 1, 1); | |
547 | } | |
548 | EXPORT_SYMBOL_GPL(sprint_symbol_build_id); | |
549 | ||
4796dd20 SB |
550 | /** |
551 | * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer | |
552 | * @buffer: buffer to be stored | |
553 | * @address: address to lookup | |
554 | * | |
555 | * This function looks up a kernel symbol with @address and stores its name | |
556 | * and module name to @buffer if possible. If no symbol was found, just saves | |
557 | * its @address as is. | |
558 | * | |
559 | * This function returns the number of bytes stored in @buffer. | |
560 | */ | |
561 | int sprint_symbol_no_offset(char *buffer, unsigned long address) | |
562 | { | |
9294523e | 563 | return __sprint_symbol(buffer, address, 0, 0, 0); |
4796dd20 SB |
564 | } |
565 | EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); | |
566 | ||
0f77a8d3 NK |
567 | /** |
568 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer | |
569 | * @buffer: buffer to be stored | |
570 | * @address: address to lookup | |
571 | * | |
572 | * This function is for stack backtrace and does the same thing as | |
573 | * sprint_symbol() but with modified/decreased @address. If there is a | |
574 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
575 | * the call so that the stack-saved return address could point outside of the | |
576 | * caller. This function ensures that kallsyms will find the original caller | |
577 | * by decreasing @address. | |
578 | * | |
579 | * This function returns the number of bytes stored in @buffer. | |
580 | */ | |
581 | int sprint_backtrace(char *buffer, unsigned long address) | |
582 | { | |
9294523e SB |
583 | return __sprint_symbol(buffer, address, -1, 1, 0); |
584 | } | |
585 | ||
586 | /** | |
587 | * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer | |
588 | * @buffer: buffer to be stored | |
589 | * @address: address to lookup | |
590 | * | |
591 | * This function is for stack backtrace and does the same thing as | |
592 | * sprint_symbol() but with modified/decreased @address. If there is a | |
593 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
594 | * the call so that the stack-saved return address could point outside of the | |
595 | * caller. This function ensures that kallsyms will find the original caller | |
596 | * by decreasing @address. This function also appends the module build ID to | |
597 | * the @buffer if @address is within a kernel module. | |
598 | * | |
599 | * This function returns the number of bytes stored in @buffer. | |
600 | */ | |
601 | int sprint_backtrace_build_id(char *buffer, unsigned long address) | |
602 | { | |
603 | return __sprint_symbol(buffer, address, -1, 1, 1); | |
0f77a8d3 NK |
604 | } |
605 | ||
1da177e4 | 606 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ |
ad6ccfad | 607 | struct kallsym_iter { |
1da177e4 | 608 | loff_t pos; |
74451e66 | 609 | loff_t pos_mod_end; |
6171a031 | 610 | loff_t pos_ftrace_mod_end; |
d002b8bc | 611 | loff_t pos_bpf_end; |
1da177e4 | 612 | unsigned long value; |
ad6ccfad | 613 | unsigned int nameoff; /* If iterating in core kernel symbols. */ |
1da177e4 | 614 | char type; |
9281acea TH |
615 | char name[KSYM_NAME_LEN]; |
616 | char module_name[MODULE_NAME_LEN]; | |
ea07890a | 617 | int exported; |
c0f3ea15 | 618 | int show_value; |
1da177e4 LT |
619 | }; |
620 | ||
1da177e4 LT |
621 | static int get_ksymbol_mod(struct kallsym_iter *iter) |
622 | { | |
15d5daa0 | 623 | int ret = module_get_kallsym(iter->pos - kallsyms_num_syms, |
74451e66 DB |
624 | &iter->value, &iter->type, |
625 | iter->name, iter->module_name, | |
626 | &iter->exported); | |
627 | if (ret < 0) { | |
628 | iter->pos_mod_end = iter->pos; | |
1da177e4 | 629 | return 0; |
74451e66 DB |
630 | } |
631 | ||
1da177e4 LT |
632 | return 1; |
633 | } | |
634 | ||
fc0ea795 AH |
635 | /* |
636 | * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace | |
637 | * purposes. In that case "__builtin__ftrace" is used as a module name, even | |
638 | * though "__builtin__ftrace" is not a module. | |
639 | */ | |
6171a031 SRV |
640 | static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter) |
641 | { | |
642 | int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end, | |
643 | &iter->value, &iter->type, | |
644 | iter->name, iter->module_name, | |
645 | &iter->exported); | |
646 | if (ret < 0) { | |
647 | iter->pos_ftrace_mod_end = iter->pos; | |
648 | return 0; | |
649 | } | |
650 | ||
651 | return 1; | |
652 | } | |
653 | ||
74451e66 DB |
654 | static int get_ksymbol_bpf(struct kallsym_iter *iter) |
655 | { | |
d002b8bc AH |
656 | int ret; |
657 | ||
33457938 | 658 | strscpy(iter->module_name, "bpf", MODULE_NAME_LEN); |
74451e66 | 659 | iter->exported = 0; |
d002b8bc AH |
660 | ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end, |
661 | &iter->value, &iter->type, | |
662 | iter->name); | |
663 | if (ret < 0) { | |
664 | iter->pos_bpf_end = iter->pos; | |
665 | return 0; | |
666 | } | |
667 | ||
668 | return 1; | |
669 | } | |
670 | ||
671 | /* | |
672 | * This uses "__builtin__kprobes" as a module name for symbols for pages | |
673 | * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a | |
674 | * module. | |
675 | */ | |
676 | static int get_ksymbol_kprobe(struct kallsym_iter *iter) | |
677 | { | |
33457938 | 678 | strscpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN); |
d002b8bc AH |
679 | iter->exported = 0; |
680 | return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end, | |
681 | &iter->value, &iter->type, | |
682 | iter->name) < 0 ? 0 : 1; | |
74451e66 DB |
683 | } |
684 | ||
1da177e4 LT |
685 | /* Returns space to next name. */ |
686 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
687 | { | |
688 | unsigned off = iter->nameoff; | |
689 | ||
ea07890a | 690 | iter->module_name[0] = '\0'; |
2213e9a6 | 691 | iter->value = kallsyms_sym_address(iter->pos); |
1da177e4 LT |
692 | |
693 | iter->type = kallsyms_get_symbol_type(off); | |
694 | ||
e3f26752 | 695 | off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name)); |
1da177e4 LT |
696 | |
697 | return off - iter->nameoff; | |
698 | } | |
699 | ||
700 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
701 | { | |
702 | iter->name[0] = '\0'; | |
703 | iter->nameoff = get_symbol_offset(new_pos); | |
704 | iter->pos = new_pos; | |
6171a031 | 705 | if (new_pos == 0) { |
74451e66 | 706 | iter->pos_mod_end = 0; |
6171a031 | 707 | iter->pos_ftrace_mod_end = 0; |
d002b8bc | 708 | iter->pos_bpf_end = 0; |
6171a031 | 709 | } |
74451e66 DB |
710 | } |
711 | ||
b9667942 AH |
712 | /* |
713 | * The end position (last + 1) of each additional kallsyms section is recorded | |
714 | * in iter->pos_..._end as each section is added, and so can be used to | |
715 | * determine which get_ksymbol_...() function to call next. | |
716 | */ | |
74451e66 DB |
717 | static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) |
718 | { | |
719 | iter->pos = pos; | |
720 | ||
b9667942 AH |
721 | if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && |
722 | get_ksymbol_mod(iter)) | |
6171a031 | 723 | return 1; |
6171a031 | 724 | |
b9667942 AH |
725 | if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) && |
726 | get_ksymbol_ftrace_mod(iter)) | |
727 | return 1; | |
74451e66 | 728 | |
d002b8bc AH |
729 | if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) && |
730 | get_ksymbol_bpf(iter)) | |
731 | return 1; | |
732 | ||
733 | return get_ksymbol_kprobe(iter); | |
1da177e4 LT |
734 | } |
735 | ||
736 | /* Returns false if pos at or past end of file. */ | |
737 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
738 | { | |
739 | /* Module symbols can be accessed randomly. */ | |
74451e66 DB |
740 | if (pos >= kallsyms_num_syms) |
741 | return update_iter_mod(iter, pos); | |
ad6ccfad | 742 | |
1da177e4 LT |
743 | /* If we're not on the desired position, reset to new position. */ |
744 | if (pos != iter->pos) | |
745 | reset_iter(iter, pos); | |
746 | ||
747 | iter->nameoff += get_ksymbol_core(iter); | |
748 | iter->pos++; | |
749 | ||
750 | return 1; | |
751 | } | |
752 | ||
753 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
754 | { | |
755 | (*pos)++; | |
756 | ||
757 | if (!update_iter(m->private, *pos)) | |
758 | return NULL; | |
759 | return p; | |
760 | } | |
761 | ||
762 | static void *s_start(struct seq_file *m, loff_t *pos) | |
763 | { | |
764 | if (!update_iter(m->private, *pos)) | |
765 | return NULL; | |
766 | return m->private; | |
767 | } | |
768 | ||
769 | static void s_stop(struct seq_file *m, void *p) | |
770 | { | |
771 | } | |
772 | ||
773 | static int s_show(struct seq_file *m, void *p) | |
774 | { | |
668533dc | 775 | void *value; |
1da177e4 LT |
776 | struct kallsym_iter *iter = m->private; |
777 | ||
ad6ccfad | 778 | /* Some debugging symbols have no name. Ignore them. */ |
1da177e4 LT |
779 | if (!iter->name[0]) |
780 | return 0; | |
781 | ||
668533dc | 782 | value = iter->show_value ? (void *)iter->value : NULL; |
c0f3ea15 | 783 | |
ea07890a AD |
784 | if (iter->module_name[0]) { |
785 | char type; | |
786 | ||
ad6ccfad MK |
787 | /* |
788 | * Label it "global" if it is exported, | |
789 | * "local" if not exported. | |
790 | */ | |
ea07890a AD |
791 | type = iter->exported ? toupper(iter->type) : |
792 | tolower(iter->type); | |
668533dc | 793 | seq_printf(m, "%px %c %s\t[%s]\n", value, |
9f36e2c4 | 794 | type, iter->name, iter->module_name); |
ea07890a | 795 | } else |
668533dc | 796 | seq_printf(m, "%px %c %s\n", value, |
9f36e2c4 | 797 | iter->type, iter->name); |
1da177e4 LT |
798 | return 0; |
799 | } | |
800 | ||
15ad7cdc | 801 | static const struct seq_operations kallsyms_op = { |
1da177e4 LT |
802 | .start = s_start, |
803 | .next = s_next, | |
804 | .stop = s_stop, | |
805 | .show = s_show | |
806 | }; | |
807 | ||
647cafa2 AM |
808 | #ifdef CONFIG_BPF_SYSCALL |
809 | ||
810 | struct bpf_iter__ksym { | |
811 | __bpf_md_ptr(struct bpf_iter_meta *, meta); | |
812 | __bpf_md_ptr(struct kallsym_iter *, ksym); | |
813 | }; | |
814 | ||
815 | static int ksym_prog_seq_show(struct seq_file *m, bool in_stop) | |
816 | { | |
817 | struct bpf_iter__ksym ctx; | |
818 | struct bpf_iter_meta meta; | |
819 | struct bpf_prog *prog; | |
820 | ||
821 | meta.seq = m; | |
822 | prog = bpf_iter_get_info(&meta, in_stop); | |
823 | if (!prog) | |
824 | return 0; | |
825 | ||
826 | ctx.meta = &meta; | |
827 | ctx.ksym = m ? m->private : NULL; | |
828 | return bpf_iter_run_prog(prog, &ctx); | |
829 | } | |
830 | ||
831 | static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p) | |
832 | { | |
833 | return ksym_prog_seq_show(m, false); | |
834 | } | |
835 | ||
836 | static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p) | |
837 | { | |
838 | if (!p) | |
839 | (void) ksym_prog_seq_show(m, true); | |
840 | else | |
841 | s_stop(m, p); | |
842 | } | |
843 | ||
844 | static const struct seq_operations bpf_iter_ksym_ops = { | |
845 | .start = s_start, | |
846 | .next = s_next, | |
847 | .stop = bpf_iter_ksym_seq_stop, | |
848 | .show = bpf_iter_ksym_seq_show, | |
849 | }; | |
850 | ||
851 | static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux) | |
852 | { | |
853 | struct kallsym_iter *iter = priv_data; | |
854 | ||
855 | reset_iter(iter, 0); | |
856 | ||
857 | /* cache here as in kallsyms_open() case; use current process | |
858 | * credentials to tell BPF iterators if values should be shown. | |
859 | */ | |
860 | iter->show_value = kallsyms_show_value(current_cred()); | |
861 | ||
862 | return 0; | |
863 | } | |
864 | ||
865 | DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym) | |
866 | ||
867 | static const struct bpf_iter_seq_info ksym_iter_seq_info = { | |
868 | .seq_ops = &bpf_iter_ksym_ops, | |
869 | .init_seq_private = bpf_iter_ksym_init, | |
870 | .fini_seq_private = NULL, | |
871 | .seq_priv_size = sizeof(struct kallsym_iter), | |
872 | }; | |
873 | ||
874 | static struct bpf_iter_reg ksym_iter_reg_info = { | |
875 | .target = "ksym", | |
876 | .feature = BPF_ITER_RESCHED, | |
877 | .ctx_arg_info_size = 1, | |
878 | .ctx_arg_info = { | |
879 | { offsetof(struct bpf_iter__ksym, ksym), | |
880 | PTR_TO_BTF_ID_OR_NULL }, | |
881 | }, | |
882 | .seq_info = &ksym_iter_seq_info, | |
883 | }; | |
884 | ||
885 | BTF_ID_LIST(btf_ksym_iter_id) | |
886 | BTF_ID(struct, kallsym_iter) | |
887 | ||
888 | static int __init bpf_ksym_iter_register(void) | |
889 | { | |
890 | ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id; | |
891 | return bpf_iter_reg_target(&ksym_iter_reg_info); | |
892 | } | |
893 | ||
894 | late_initcall(bpf_ksym_iter_register); | |
895 | ||
896 | #endif /* CONFIG_BPF_SYSCALL */ | |
897 | ||
1da177e4 LT |
898 | static int kallsyms_open(struct inode *inode, struct file *file) |
899 | { | |
ad6ccfad MK |
900 | /* |
901 | * We keep iterator in m->private, since normal case is to | |
1da177e4 | 902 | * s_start from where we left off, so we avoid doing |
ad6ccfad MK |
903 | * using get_symbol_offset for every symbol. |
904 | */ | |
1da177e4 | 905 | struct kallsym_iter *iter; |
0049f26a | 906 | iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter)); |
1da177e4 LT |
907 | if (!iter) |
908 | return -ENOMEM; | |
909 | reset_iter(iter, 0); | |
910 | ||
16025184 KC |
911 | /* |
912 | * Instead of checking this on every s_show() call, cache | |
913 | * the result here at open time. | |
914 | */ | |
915 | iter->show_value = kallsyms_show_value(file->f_cred); | |
0049f26a | 916 | return 0; |
1da177e4 LT |
917 | } |
918 | ||
67fc4e0c JW |
919 | #ifdef CONFIG_KGDB_KDB |
920 | const char *kdb_walk_kallsyms(loff_t *pos) | |
921 | { | |
922 | static struct kallsym_iter kdb_walk_kallsyms_iter; | |
923 | if (*pos == 0) { | |
924 | memset(&kdb_walk_kallsyms_iter, 0, | |
925 | sizeof(kdb_walk_kallsyms_iter)); | |
926 | reset_iter(&kdb_walk_kallsyms_iter, 0); | |
927 | } | |
928 | while (1) { | |
929 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) | |
930 | return NULL; | |
931 | ++*pos; | |
932 | /* Some debugging symbols have no name. Ignore them. */ | |
933 | if (kdb_walk_kallsyms_iter.name[0]) | |
934 | return kdb_walk_kallsyms_iter.name; | |
935 | } | |
936 | } | |
937 | #endif /* CONFIG_KGDB_KDB */ | |
938 | ||
97a32539 AD |
939 | static const struct proc_ops kallsyms_proc_ops = { |
940 | .proc_open = kallsyms_open, | |
941 | .proc_read = seq_read, | |
942 | .proc_lseek = seq_lseek, | |
943 | .proc_release = seq_release_private, | |
1da177e4 LT |
944 | }; |
945 | ||
946 | static int __init kallsyms_init(void) | |
947 | { | |
97a32539 | 948 | proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops); |
1da177e4 LT |
949 | return 0; |
950 | } | |
ad6ccfad | 951 | device_initcall(kallsyms_init); |