Commit | Line | Data |
---|---|---|
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 | ||
6eb4bd92 | 167 | static bool cleanup_symbol_name(char *s) |
8b8e6b5d ST |
168 | { |
169 | char *res; | |
170 | ||
6eb4bd92 ND |
171 | if (!IS_ENABLED(CONFIG_LTO_CLANG)) |
172 | return false; | |
173 | ||
174 | /* | |
175 | * LLVM appends various suffixes for local functions and variables that | |
176 | * must be promoted to global scope as part of LTO. This can break | |
177 | * hooking of static functions with kprobes. '.' is not a valid | |
178 | * character in an identifier in C. Suffixes observed: | |
179 | * - foo.llvm.[0-9a-f]+ | |
180 | * - foo.[0-9a-f]+ | |
181 | * - foo.[0-9a-f]+.cfi_jt | |
182 | */ | |
183 | res = strchr(s, '.'); | |
184 | if (res) { | |
185 | *res = '\0'; | |
186 | return true; | |
187 | } | |
188 | ||
189 | if (!IS_ENABLED(CONFIG_CFI_CLANG) || | |
190 | !IS_ENABLED(CONFIG_LTO_CLANG_THIN) || | |
191 | CONFIG_CLANG_VERSION >= 130000) | |
192 | return false; | |
193 | ||
194 | /* | |
195 | * Prior to LLVM 13, the following suffixes were observed when thinLTO | |
196 | * and CFI are both enabled: | |
197 | * - foo$[0-9]+ | |
198 | */ | |
8b8e6b5d | 199 | res = strrchr(s, '$'); |
6eb4bd92 | 200 | if (res) { |
8b8e6b5d | 201 | *res = '\0'; |
6eb4bd92 ND |
202 | return true; |
203 | } | |
8b8e6b5d | 204 | |
6eb4bd92 | 205 | return false; |
8b8e6b5d | 206 | } |
8b8e6b5d | 207 | |
1da177e4 LT |
208 | /* Lookup the address for this symbol. Returns 0 if not found. */ |
209 | unsigned long kallsyms_lookup_name(const char *name) | |
210 | { | |
9281acea | 211 | char namebuf[KSYM_NAME_LEN]; |
1da177e4 LT |
212 | unsigned long i; |
213 | unsigned int off; | |
214 | ||
aecf489f JO |
215 | /* Skip the search for empty string. */ |
216 | if (!*name) | |
217 | return 0; | |
218 | ||
1da177e4 | 219 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
e3f26752 | 220 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
1da177e4 LT |
221 | |
222 | if (strcmp(namebuf, name) == 0) | |
2213e9a6 | 223 | return kallsyms_sym_address(i); |
8b8e6b5d ST |
224 | |
225 | if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0) | |
226 | return kallsyms_sym_address(i); | |
1da177e4 LT |
227 | } |
228 | return module_kallsyms_lookup_name(name); | |
229 | } | |
1da177e4 | 230 | |
013c1667 CH |
231 | /* |
232 | * Iterate over all symbols in vmlinux. For symbols from modules use | |
233 | * module_kallsyms_on_each_symbol instead. | |
234 | */ | |
75a66614 AK |
235 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, |
236 | unsigned long), | |
237 | void *data) | |
238 | { | |
239 | char namebuf[KSYM_NAME_LEN]; | |
240 | unsigned long i; | |
241 | unsigned int off; | |
242 | int ret; | |
243 | ||
244 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
e3f26752 | 245 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
2213e9a6 | 246 | ret = fn(data, namebuf, NULL, kallsyms_sym_address(i)); |
75a66614 AK |
247 | if (ret != 0) |
248 | return ret; | |
f5bdb34b | 249 | cond_resched(); |
75a66614 | 250 | } |
013c1667 | 251 | return 0; |
75a66614 | 252 | } |
75a66614 | 253 | |
ffc50891 FBH |
254 | static unsigned long get_symbol_pos(unsigned long addr, |
255 | unsigned long *symbolsize, | |
256 | unsigned long *offset) | |
257 | { | |
258 | unsigned long symbol_start = 0, symbol_end = 0; | |
259 | unsigned long i, low, high, mid; | |
260 | ||
2ea03891 | 261 | /* This kernel should never had been booted. */ |
2213e9a6 AB |
262 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) |
263 | BUG_ON(!kallsyms_addresses); | |
264 | else | |
265 | BUG_ON(!kallsyms_offsets); | |
2ea03891 | 266 | |
ad6ccfad | 267 | /* Do a binary search on the sorted kallsyms_addresses array. */ |
ffc50891 FBH |
268 | low = 0; |
269 | high = kallsyms_num_syms; | |
270 | ||
271 | while (high - low > 1) { | |
2fc9c4e1 | 272 | mid = low + (high - low) / 2; |
2213e9a6 | 273 | if (kallsyms_sym_address(mid) <= addr) |
ffc50891 FBH |
274 | low = mid; |
275 | else | |
276 | high = mid; | |
277 | } | |
278 | ||
279 | /* | |
ad6ccfad MK |
280 | * Search for the first aliased symbol. Aliased |
281 | * symbols are symbols with the same address. | |
ffc50891 | 282 | */ |
2213e9a6 | 283 | while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low)) |
ffc50891 FBH |
284 | --low; |
285 | ||
2213e9a6 | 286 | symbol_start = kallsyms_sym_address(low); |
ffc50891 | 287 | |
ad6ccfad | 288 | /* Search for next non-aliased symbol. */ |
ffc50891 | 289 | for (i = low + 1; i < kallsyms_num_syms; i++) { |
2213e9a6 AB |
290 | if (kallsyms_sym_address(i) > symbol_start) { |
291 | symbol_end = kallsyms_sym_address(i); | |
ffc50891 FBH |
292 | break; |
293 | } | |
294 | } | |
295 | ||
ad6ccfad | 296 | /* If we found no next symbol, we use the end of the section. */ |
ffc50891 FBH |
297 | if (!symbol_end) { |
298 | if (is_kernel_inittext(addr)) | |
299 | symbol_end = (unsigned long)_einittext; | |
63b23e2c | 300 | else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) |
ffc50891 FBH |
301 | symbol_end = (unsigned long)_end; |
302 | else | |
303 | symbol_end = (unsigned long)_etext; | |
304 | } | |
305 | ||
ffb45122 AD |
306 | if (symbolsize) |
307 | *symbolsize = symbol_end - symbol_start; | |
308 | if (offset) | |
309 | *offset = addr - symbol_start; | |
ffc50891 FBH |
310 | |
311 | return low; | |
312 | } | |
313 | ||
314 | /* | |
315 | * Lookup an address but don't bother to find any names. | |
316 | */ | |
317 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, | |
318 | unsigned long *offset) | |
319 | { | |
6dd06c9f | 320 | char namebuf[KSYM_NAME_LEN]; |
74451e66 | 321 | |
2a1a3fa0 MZ |
322 | if (is_ksym_addr(addr)) { |
323 | get_symbol_pos(addr, symbolsize, offset); | |
324 | return 1; | |
325 | } | |
9294523e | 326 | return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) || |
74451e66 | 327 | !!__bpf_address_lookup(addr, symbolsize, offset, namebuf); |
ffc50891 FBH |
328 | } |
329 | ||
9294523e SB |
330 | static const char *kallsyms_lookup_buildid(unsigned long addr, |
331 | unsigned long *symbolsize, | |
332 | unsigned long *offset, char **modname, | |
333 | const unsigned char **modbuildid, char *namebuf) | |
1da177e4 | 334 | { |
74451e66 DB |
335 | const char *ret; |
336 | ||
9281acea | 337 | namebuf[KSYM_NAME_LEN - 1] = 0; |
1da177e4 LT |
338 | namebuf[0] = 0; |
339 | ||
ffc50891 FBH |
340 | if (is_ksym_addr(addr)) { |
341 | unsigned long pos; | |
1da177e4 | 342 | |
ffc50891 | 343 | pos = get_symbol_pos(addr, symbolsize, offset); |
1da177e4 | 344 | /* Grab name */ |
e3f26752 CG |
345 | kallsyms_expand_symbol(get_symbol_offset(pos), |
346 | namebuf, KSYM_NAME_LEN); | |
7a74fc49 KM |
347 | if (modname) |
348 | *modname = NULL; | |
9294523e SB |
349 | if (modbuildid) |
350 | *modbuildid = NULL; | |
8b8e6b5d ST |
351 | |
352 | ret = namebuf; | |
353 | goto found; | |
1da177e4 LT |
354 | } |
355 | ||
74451e66 DB |
356 | /* See if it's in a module or a BPF JITed image. */ |
357 | ret = module_address_lookup(addr, symbolsize, offset, | |
9294523e | 358 | modname, modbuildid, namebuf); |
74451e66 DB |
359 | if (!ret) |
360 | ret = bpf_address_lookup(addr, symbolsize, | |
361 | offset, modname, namebuf); | |
aba4b5c2 SRV |
362 | |
363 | if (!ret) | |
364 | ret = ftrace_mod_address_lookup(addr, symbolsize, | |
365 | offset, modname, namebuf); | |
8b8e6b5d ST |
366 | |
367 | found: | |
368 | cleanup_symbol_name(namebuf); | |
74451e66 | 369 | return ret; |
1da177e4 LT |
370 | } |
371 | ||
9294523e SB |
372 | /* |
373 | * Lookup an address | |
374 | * - modname is set to NULL if it's in the kernel. | |
375 | * - We guarantee that the returned name is valid until we reschedule even if. | |
376 | * It resides in a module. | |
377 | * - We also guarantee that modname will be valid until rescheduled. | |
378 | */ | |
379 | const char *kallsyms_lookup(unsigned long addr, | |
380 | unsigned long *symbolsize, | |
381 | unsigned long *offset, | |
382 | char **modname, char *namebuf) | |
383 | { | |
384 | return kallsyms_lookup_buildid(addr, symbolsize, offset, modname, | |
385 | NULL, namebuf); | |
386 | } | |
387 | ||
9d65cb4a AD |
388 | int lookup_symbol_name(unsigned long addr, char *symname) |
389 | { | |
8b8e6b5d ST |
390 | int res; |
391 | ||
9d65cb4a | 392 | symname[0] = '\0'; |
9281acea | 393 | symname[KSYM_NAME_LEN - 1] = '\0'; |
9d65cb4a AD |
394 | |
395 | if (is_ksym_addr(addr)) { | |
396 | unsigned long pos; | |
397 | ||
398 | pos = get_symbol_pos(addr, NULL, NULL); | |
399 | /* Grab name */ | |
e3f26752 CG |
400 | kallsyms_expand_symbol(get_symbol_offset(pos), |
401 | symname, KSYM_NAME_LEN); | |
8b8e6b5d | 402 | goto found; |
9d65cb4a | 403 | } |
ad6ccfad | 404 | /* See if it's in a module. */ |
8b8e6b5d ST |
405 | res = lookup_module_symbol_name(addr, symname); |
406 | if (res) | |
407 | return res; | |
408 | ||
409 | found: | |
410 | cleanup_symbol_name(symname); | |
411 | return 0; | |
9d65cb4a AD |
412 | } |
413 | ||
a5c43dae AD |
414 | int lookup_symbol_attrs(unsigned long addr, unsigned long *size, |
415 | unsigned long *offset, char *modname, char *name) | |
416 | { | |
8b8e6b5d ST |
417 | int res; |
418 | ||
a5c43dae | 419 | name[0] = '\0'; |
9281acea | 420 | name[KSYM_NAME_LEN - 1] = '\0'; |
a5c43dae AD |
421 | |
422 | if (is_ksym_addr(addr)) { | |
423 | unsigned long pos; | |
424 | ||
425 | pos = get_symbol_pos(addr, size, offset); | |
426 | /* Grab name */ | |
e3f26752 CG |
427 | kallsyms_expand_symbol(get_symbol_offset(pos), |
428 | name, KSYM_NAME_LEN); | |
a5c43dae | 429 | modname[0] = '\0'; |
8b8e6b5d | 430 | goto found; |
a5c43dae | 431 | } |
ad6ccfad | 432 | /* See if it's in a module. */ |
8b8e6b5d ST |
433 | res = lookup_module_symbol_attrs(addr, size, offset, modname, name); |
434 | if (res) | |
435 | return res; | |
436 | ||
437 | found: | |
438 | cleanup_symbol_name(name); | |
439 | return 0; | |
a5c43dae AD |
440 | } |
441 | ||
42e38083 | 442 | /* Look up a kernel symbol and return it in a text buffer. */ |
0f77a8d3 | 443 | static int __sprint_symbol(char *buffer, unsigned long address, |
9294523e | 444 | int symbol_offset, int add_offset, int add_buildid) |
1da177e4 LT |
445 | { |
446 | char *modname; | |
9294523e | 447 | const unsigned char *buildid; |
1da177e4 LT |
448 | const char *name; |
449 | unsigned long offset, size; | |
966c8c12 | 450 | int len; |
1da177e4 | 451 | |
0f77a8d3 | 452 | address += symbol_offset; |
9294523e SB |
453 | name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid, |
454 | buffer); | |
1da177e4 | 455 | if (!name) |
b86280aa | 456 | return sprintf(buffer, "0x%lx", address - symbol_offset); |
19769b76 | 457 | |
966c8c12 HD |
458 | if (name != buffer) |
459 | strcpy(buffer, name); | |
460 | len = strlen(buffer); | |
0f77a8d3 | 461 | offset -= symbol_offset; |
966c8c12 | 462 | |
4796dd20 SB |
463 | if (add_offset) |
464 | len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); | |
465 | ||
9294523e SB |
466 | if (modname) { |
467 | len += sprintf(buffer + len, " [%s", modname); | |
468 | #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) | |
469 | if (add_buildid && buildid) { | |
470 | /* build ID should match length of sprintf */ | |
471 | #if IS_ENABLED(CONFIG_MODULES) | |
472 | static_assert(sizeof(typeof_member(struct module, build_id)) == 20); | |
473 | #endif | |
474 | len += sprintf(buffer + len, " %20phN", buildid); | |
475 | } | |
476 | #endif | |
477 | len += sprintf(buffer + len, "]"); | |
478 | } | |
966c8c12 HD |
479 | |
480 | return len; | |
42e38083 | 481 | } |
0f77a8d3 NK |
482 | |
483 | /** | |
484 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer | |
485 | * @buffer: buffer to be stored | |
486 | * @address: address to lookup | |
487 | * | |
488 | * This function looks up a kernel symbol with @address and stores its name, | |
489 | * offset, size and module name to @buffer if possible. If no symbol was found, | |
490 | * just saves its @address as is. | |
491 | * | |
492 | * This function returns the number of bytes stored in @buffer. | |
493 | */ | |
494 | int sprint_symbol(char *buffer, unsigned long address) | |
495 | { | |
9294523e | 496 | return __sprint_symbol(buffer, address, 0, 1, 0); |
0f77a8d3 | 497 | } |
ad6ccfad | 498 | EXPORT_SYMBOL_GPL(sprint_symbol); |
42e38083 | 499 | |
9294523e SB |
500 | /** |
501 | * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer | |
502 | * @buffer: buffer to be stored | |
503 | * @address: address to lookup | |
504 | * | |
505 | * This function looks up a kernel symbol with @address and stores its name, | |
506 | * offset, size, module name and module build ID to @buffer if possible. If no | |
507 | * symbol was found, just saves its @address as is. | |
508 | * | |
509 | * This function returns the number of bytes stored in @buffer. | |
510 | */ | |
511 | int sprint_symbol_build_id(char *buffer, unsigned long address) | |
512 | { | |
513 | return __sprint_symbol(buffer, address, 0, 1, 1); | |
514 | } | |
515 | EXPORT_SYMBOL_GPL(sprint_symbol_build_id); | |
516 | ||
4796dd20 SB |
517 | /** |
518 | * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer | |
519 | * @buffer: buffer to be stored | |
520 | * @address: address to lookup | |
521 | * | |
522 | * This function looks up a kernel symbol with @address and stores its name | |
523 | * and module name to @buffer if possible. If no symbol was found, just saves | |
524 | * its @address as is. | |
525 | * | |
526 | * This function returns the number of bytes stored in @buffer. | |
527 | */ | |
528 | int sprint_symbol_no_offset(char *buffer, unsigned long address) | |
529 | { | |
9294523e | 530 | return __sprint_symbol(buffer, address, 0, 0, 0); |
4796dd20 SB |
531 | } |
532 | EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); | |
533 | ||
0f77a8d3 NK |
534 | /** |
535 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer | |
536 | * @buffer: buffer to be stored | |
537 | * @address: address to lookup | |
538 | * | |
539 | * This function is for stack backtrace and does the same thing as | |
540 | * sprint_symbol() but with modified/decreased @address. If there is a | |
541 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
542 | * the call so that the stack-saved return address could point outside of the | |
543 | * caller. This function ensures that kallsyms will find the original caller | |
544 | * by decreasing @address. | |
545 | * | |
546 | * This function returns the number of bytes stored in @buffer. | |
547 | */ | |
548 | int sprint_backtrace(char *buffer, unsigned long address) | |
549 | { | |
9294523e SB |
550 | return __sprint_symbol(buffer, address, -1, 1, 0); |
551 | } | |
552 | ||
553 | /** | |
554 | * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer | |
555 | * @buffer: buffer to be stored | |
556 | * @address: address to lookup | |
557 | * | |
558 | * This function is for stack backtrace and does the same thing as | |
559 | * sprint_symbol() but with modified/decreased @address. If there is a | |
560 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
561 | * the call so that the stack-saved return address could point outside of the | |
562 | * caller. This function ensures that kallsyms will find the original caller | |
563 | * by decreasing @address. This function also appends the module build ID to | |
564 | * the @buffer if @address is within a kernel module. | |
565 | * | |
566 | * This function returns the number of bytes stored in @buffer. | |
567 | */ | |
568 | int sprint_backtrace_build_id(char *buffer, unsigned long address) | |
569 | { | |
570 | return __sprint_symbol(buffer, address, -1, 1, 1); | |
0f77a8d3 NK |
571 | } |
572 | ||
1da177e4 | 573 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ |
ad6ccfad | 574 | struct kallsym_iter { |
1da177e4 | 575 | loff_t pos; |
d83212d5 | 576 | loff_t pos_arch_end; |
74451e66 | 577 | loff_t pos_mod_end; |
6171a031 | 578 | loff_t pos_ftrace_mod_end; |
d002b8bc | 579 | loff_t pos_bpf_end; |
1da177e4 | 580 | unsigned long value; |
ad6ccfad | 581 | unsigned int nameoff; /* If iterating in core kernel symbols. */ |
1da177e4 | 582 | char type; |
9281acea TH |
583 | char name[KSYM_NAME_LEN]; |
584 | char module_name[MODULE_NAME_LEN]; | |
ea07890a | 585 | int exported; |
c0f3ea15 | 586 | int show_value; |
1da177e4 LT |
587 | }; |
588 | ||
d83212d5 AS |
589 | int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value, |
590 | char *type, char *name) | |
591 | { | |
592 | return -EINVAL; | |
593 | } | |
594 | ||
595 | static int get_ksymbol_arch(struct kallsym_iter *iter) | |
596 | { | |
597 | int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms, | |
598 | &iter->value, &iter->type, | |
599 | iter->name); | |
600 | ||
601 | if (ret < 0) { | |
602 | iter->pos_arch_end = iter->pos; | |
603 | return 0; | |
604 | } | |
605 | ||
606 | return 1; | |
607 | } | |
608 | ||
1da177e4 LT |
609 | static int get_ksymbol_mod(struct kallsym_iter *iter) |
610 | { | |
d83212d5 | 611 | int ret = module_get_kallsym(iter->pos - iter->pos_arch_end, |
74451e66 DB |
612 | &iter->value, &iter->type, |
613 | iter->name, iter->module_name, | |
614 | &iter->exported); | |
615 | if (ret < 0) { | |
616 | iter->pos_mod_end = iter->pos; | |
1da177e4 | 617 | return 0; |
74451e66 DB |
618 | } |
619 | ||
1da177e4 LT |
620 | return 1; |
621 | } | |
622 | ||
fc0ea795 AH |
623 | /* |
624 | * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace | |
625 | * purposes. In that case "__builtin__ftrace" is used as a module name, even | |
626 | * though "__builtin__ftrace" is not a module. | |
627 | */ | |
6171a031 SRV |
628 | static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter) |
629 | { | |
630 | int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end, | |
631 | &iter->value, &iter->type, | |
632 | iter->name, iter->module_name, | |
633 | &iter->exported); | |
634 | if (ret < 0) { | |
635 | iter->pos_ftrace_mod_end = iter->pos; | |
636 | return 0; | |
637 | } | |
638 | ||
639 | return 1; | |
640 | } | |
641 | ||
74451e66 DB |
642 | static int get_ksymbol_bpf(struct kallsym_iter *iter) |
643 | { | |
d002b8bc AH |
644 | int ret; |
645 | ||
6934058d | 646 | strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN); |
74451e66 | 647 | iter->exported = 0; |
d002b8bc AH |
648 | ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end, |
649 | &iter->value, &iter->type, | |
650 | iter->name); | |
651 | if (ret < 0) { | |
652 | iter->pos_bpf_end = iter->pos; | |
653 | return 0; | |
654 | } | |
655 | ||
656 | return 1; | |
657 | } | |
658 | ||
659 | /* | |
660 | * This uses "__builtin__kprobes" as a module name for symbols for pages | |
661 | * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a | |
662 | * module. | |
663 | */ | |
664 | static int get_ksymbol_kprobe(struct kallsym_iter *iter) | |
665 | { | |
666 | strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN); | |
667 | iter->exported = 0; | |
668 | return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end, | |
669 | &iter->value, &iter->type, | |
670 | iter->name) < 0 ? 0 : 1; | |
74451e66 DB |
671 | } |
672 | ||
1da177e4 LT |
673 | /* Returns space to next name. */ |
674 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
675 | { | |
676 | unsigned off = iter->nameoff; | |
677 | ||
ea07890a | 678 | iter->module_name[0] = '\0'; |
2213e9a6 | 679 | iter->value = kallsyms_sym_address(iter->pos); |
1da177e4 LT |
680 | |
681 | iter->type = kallsyms_get_symbol_type(off); | |
682 | ||
e3f26752 | 683 | off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name)); |
1da177e4 LT |
684 | |
685 | return off - iter->nameoff; | |
686 | } | |
687 | ||
688 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
689 | { | |
690 | iter->name[0] = '\0'; | |
691 | iter->nameoff = get_symbol_offset(new_pos); | |
692 | iter->pos = new_pos; | |
6171a031 | 693 | if (new_pos == 0) { |
d83212d5 | 694 | iter->pos_arch_end = 0; |
74451e66 | 695 | iter->pos_mod_end = 0; |
6171a031 | 696 | iter->pos_ftrace_mod_end = 0; |
d002b8bc | 697 | iter->pos_bpf_end = 0; |
6171a031 | 698 | } |
74451e66 DB |
699 | } |
700 | ||
b9667942 AH |
701 | /* |
702 | * The end position (last + 1) of each additional kallsyms section is recorded | |
703 | * in iter->pos_..._end as each section is added, and so can be used to | |
704 | * determine which get_ksymbol_...() function to call next. | |
705 | */ | |
74451e66 DB |
706 | static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) |
707 | { | |
708 | iter->pos = pos; | |
709 | ||
d83212d5 AS |
710 | if ((!iter->pos_arch_end || iter->pos_arch_end > pos) && |
711 | get_ksymbol_arch(iter)) | |
712 | return 1; | |
713 | ||
b9667942 AH |
714 | if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && |
715 | get_ksymbol_mod(iter)) | |
6171a031 | 716 | return 1; |
6171a031 | 717 | |
b9667942 AH |
718 | if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) && |
719 | get_ksymbol_ftrace_mod(iter)) | |
720 | return 1; | |
74451e66 | 721 | |
d002b8bc AH |
722 | if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) && |
723 | get_ksymbol_bpf(iter)) | |
724 | return 1; | |
725 | ||
726 | return get_ksymbol_kprobe(iter); | |
1da177e4 LT |
727 | } |
728 | ||
729 | /* Returns false if pos at or past end of file. */ | |
730 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
731 | { | |
732 | /* Module symbols can be accessed randomly. */ | |
74451e66 DB |
733 | if (pos >= kallsyms_num_syms) |
734 | return update_iter_mod(iter, pos); | |
ad6ccfad | 735 | |
1da177e4 LT |
736 | /* If we're not on the desired position, reset to new position. */ |
737 | if (pos != iter->pos) | |
738 | reset_iter(iter, pos); | |
739 | ||
740 | iter->nameoff += get_ksymbol_core(iter); | |
741 | iter->pos++; | |
742 | ||
743 | return 1; | |
744 | } | |
745 | ||
746 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
747 | { | |
748 | (*pos)++; | |
749 | ||
750 | if (!update_iter(m->private, *pos)) | |
751 | return NULL; | |
752 | return p; | |
753 | } | |
754 | ||
755 | static void *s_start(struct seq_file *m, loff_t *pos) | |
756 | { | |
757 | if (!update_iter(m->private, *pos)) | |
758 | return NULL; | |
759 | return m->private; | |
760 | } | |
761 | ||
762 | static void s_stop(struct seq_file *m, void *p) | |
763 | { | |
764 | } | |
765 | ||
766 | static int s_show(struct seq_file *m, void *p) | |
767 | { | |
668533dc | 768 | void *value; |
1da177e4 LT |
769 | struct kallsym_iter *iter = m->private; |
770 | ||
ad6ccfad | 771 | /* Some debugging symbols have no name. Ignore them. */ |
1da177e4 LT |
772 | if (!iter->name[0]) |
773 | return 0; | |
774 | ||
668533dc | 775 | value = iter->show_value ? (void *)iter->value : NULL; |
c0f3ea15 | 776 | |
ea07890a AD |
777 | if (iter->module_name[0]) { |
778 | char type; | |
779 | ||
ad6ccfad MK |
780 | /* |
781 | * Label it "global" if it is exported, | |
782 | * "local" if not exported. | |
783 | */ | |
ea07890a AD |
784 | type = iter->exported ? toupper(iter->type) : |
785 | tolower(iter->type); | |
668533dc | 786 | seq_printf(m, "%px %c %s\t[%s]\n", value, |
9f36e2c4 | 787 | type, iter->name, iter->module_name); |
ea07890a | 788 | } else |
668533dc | 789 | seq_printf(m, "%px %c %s\n", value, |
9f36e2c4 | 790 | iter->type, iter->name); |
1da177e4 LT |
791 | return 0; |
792 | } | |
793 | ||
15ad7cdc | 794 | static const struct seq_operations kallsyms_op = { |
1da177e4 LT |
795 | .start = s_start, |
796 | .next = s_next, | |
797 | .stop = s_stop, | |
798 | .show = s_show | |
799 | }; | |
800 | ||
c0f3ea15 LT |
801 | static inline int kallsyms_for_perf(void) |
802 | { | |
803 | #ifdef CONFIG_PERF_EVENTS | |
804 | extern int sysctl_perf_event_paranoid; | |
805 | if (sysctl_perf_event_paranoid <= 1) | |
806 | return 1; | |
807 | #endif | |
808 | return 0; | |
809 | } | |
810 | ||
811 | /* | |
812 | * We show kallsyms information even to normal users if we've enabled | |
813 | * kernel profiling and are explicitly not paranoid (so kptr_restrict | |
814 | * is clear, and sysctl_perf_event_paranoid isn't set). | |
815 | * | |
816 | * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to | |
817 | * block even that). | |
818 | */ | |
16025184 | 819 | bool kallsyms_show_value(const struct cred *cred) |
c0f3ea15 LT |
820 | { |
821 | switch (kptr_restrict) { | |
822 | case 0: | |
823 | if (kallsyms_for_perf()) | |
16025184 | 824 | return true; |
df561f66 | 825 | fallthrough; |
c0f3ea15 | 826 | case 1: |
16025184 KC |
827 | if (security_capable(cred, &init_user_ns, CAP_SYSLOG, |
828 | CAP_OPT_NOAUDIT) == 0) | |
829 | return true; | |
df561f66 | 830 | fallthrough; |
c0f3ea15 | 831 | default: |
16025184 | 832 | return false; |
c0f3ea15 LT |
833 | } |
834 | } | |
835 | ||
1da177e4 LT |
836 | static int kallsyms_open(struct inode *inode, struct file *file) |
837 | { | |
ad6ccfad MK |
838 | /* |
839 | * We keep iterator in m->private, since normal case is to | |
1da177e4 | 840 | * s_start from where we left off, so we avoid doing |
ad6ccfad MK |
841 | * using get_symbol_offset for every symbol. |
842 | */ | |
1da177e4 | 843 | struct kallsym_iter *iter; |
0049f26a | 844 | iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter)); |
1da177e4 LT |
845 | if (!iter) |
846 | return -ENOMEM; | |
847 | reset_iter(iter, 0); | |
848 | ||
16025184 KC |
849 | /* |
850 | * Instead of checking this on every s_show() call, cache | |
851 | * the result here at open time. | |
852 | */ | |
853 | iter->show_value = kallsyms_show_value(file->f_cred); | |
0049f26a | 854 | return 0; |
1da177e4 LT |
855 | } |
856 | ||
67fc4e0c JW |
857 | #ifdef CONFIG_KGDB_KDB |
858 | const char *kdb_walk_kallsyms(loff_t *pos) | |
859 | { | |
860 | static struct kallsym_iter kdb_walk_kallsyms_iter; | |
861 | if (*pos == 0) { | |
862 | memset(&kdb_walk_kallsyms_iter, 0, | |
863 | sizeof(kdb_walk_kallsyms_iter)); | |
864 | reset_iter(&kdb_walk_kallsyms_iter, 0); | |
865 | } | |
866 | while (1) { | |
867 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) | |
868 | return NULL; | |
869 | ++*pos; | |
870 | /* Some debugging symbols have no name. Ignore them. */ | |
871 | if (kdb_walk_kallsyms_iter.name[0]) | |
872 | return kdb_walk_kallsyms_iter.name; | |
873 | } | |
874 | } | |
875 | #endif /* CONFIG_KGDB_KDB */ | |
876 | ||
97a32539 AD |
877 | static const struct proc_ops kallsyms_proc_ops = { |
878 | .proc_open = kallsyms_open, | |
879 | .proc_read = seq_read, | |
880 | .proc_lseek = seq_lseek, | |
881 | .proc_release = seq_release_private, | |
1da177e4 LT |
882 | }; |
883 | ||
884 | static int __init kallsyms_init(void) | |
885 | { | |
97a32539 | 886 | proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops); |
1da177e4 LT |
887 | return 0; |
888 | } | |
ad6ccfad | 889 | device_initcall(kallsyms_init); |