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++; | |
53 | ||
ad6ccfad MK |
54 | /* |
55 | * Update the offset to return the offset for the next symbol on | |
56 | * the compressed stream. | |
57 | */ | |
1da177e4 LT |
58 | off += len + 1; |
59 | ||
ad6ccfad MK |
60 | /* |
61 | * For every byte on the compressed symbol data, copy the table | |
62 | * entry for that byte. | |
63 | */ | |
64 | while (len) { | |
65 | tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; | |
1da177e4 LT |
66 | data++; |
67 | len--; | |
68 | ||
69 | while (*tptr) { | |
ad6ccfad | 70 | if (skipped_first) { |
e3f26752 CG |
71 | if (maxlen <= 1) |
72 | goto tail; | |
1da177e4 LT |
73 | *result = *tptr; |
74 | result++; | |
e3f26752 | 75 | maxlen--; |
1da177e4 LT |
76 | } else |
77 | skipped_first = 1; | |
78 | tptr++; | |
79 | } | |
80 | } | |
81 | ||
e3f26752 CG |
82 | tail: |
83 | if (maxlen) | |
84 | *result = '\0'; | |
1da177e4 | 85 | |
ad6ccfad | 86 | /* Return to offset to the next symbol. */ |
1da177e4 LT |
87 | return off; |
88 | } | |
89 | ||
ad6ccfad MK |
90 | /* |
91 | * Get symbol type information. This is encoded as a single char at the | |
92 | * beginning of the symbol name. | |
93 | */ | |
1da177e4 LT |
94 | static char kallsyms_get_symbol_type(unsigned int off) |
95 | { | |
ad6ccfad MK |
96 | /* |
97 | * Get just the first code, look it up in the token table, | |
98 | * and return the first char from this token. | |
99 | */ | |
100 | return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; | |
1da177e4 LT |
101 | } |
102 | ||
103 | ||
ad6ccfad MK |
104 | /* |
105 | * Find the offset on the compressed stream given and index in the | |
106 | * kallsyms array. | |
107 | */ | |
1da177e4 LT |
108 | static unsigned int get_symbol_offset(unsigned long pos) |
109 | { | |
aad09470 | 110 | const u8 *name; |
1da177e4 LT |
111 | int i; |
112 | ||
ad6ccfad MK |
113 | /* |
114 | * Use the closest marker we have. We have markers every 256 positions, | |
115 | * so that should be close enough. | |
116 | */ | |
117 | name = &kallsyms_names[kallsyms_markers[pos >> 8]]; | |
1da177e4 | 118 | |
ad6ccfad MK |
119 | /* |
120 | * Sequentially scan all the symbols up to the point we're searching | |
121 | * for. Every symbol is stored in a [<len>][<len> bytes of data] format, | |
122 | * so we just need to add the len to the current pointer for every | |
123 | * symbol we wish to skip. | |
124 | */ | |
125 | for (i = 0; i < (pos & 0xFF); i++) | |
1da177e4 LT |
126 | name = name + (*name) + 1; |
127 | ||
128 | return name - kallsyms_names; | |
129 | } | |
130 | ||
2213e9a6 AB |
131 | static unsigned long kallsyms_sym_address(int idx) |
132 | { | |
133 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) | |
134 | return kallsyms_addresses[idx]; | |
135 | ||
136 | /* values are unsigned offsets if --absolute-percpu is not in effect */ | |
137 | if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU)) | |
138 | return kallsyms_relative_base + (u32)kallsyms_offsets[idx]; | |
139 | ||
140 | /* ...otherwise, positive offsets are absolute values */ | |
141 | if (kallsyms_offsets[idx] >= 0) | |
142 | return kallsyms_offsets[idx]; | |
143 | ||
144 | /* ...and negative offsets are relative to kallsyms_relative_base - 1 */ | |
145 | return kallsyms_relative_base - 1 - kallsyms_offsets[idx]; | |
146 | } | |
147 | ||
6eb4bd92 | 148 | static bool cleanup_symbol_name(char *s) |
8b8e6b5d ST |
149 | { |
150 | char *res; | |
151 | ||
6eb4bd92 ND |
152 | if (!IS_ENABLED(CONFIG_LTO_CLANG)) |
153 | return false; | |
154 | ||
155 | /* | |
156 | * LLVM appends various suffixes for local functions and variables that | |
157 | * must be promoted to global scope as part of LTO. This can break | |
158 | * hooking of static functions with kprobes. '.' is not a valid | |
159 | * character in an identifier in C. Suffixes observed: | |
160 | * - foo.llvm.[0-9a-f]+ | |
161 | * - foo.[0-9a-f]+ | |
162 | * - foo.[0-9a-f]+.cfi_jt | |
163 | */ | |
164 | res = strchr(s, '.'); | |
165 | if (res) { | |
166 | *res = '\0'; | |
167 | return true; | |
168 | } | |
169 | ||
170 | if (!IS_ENABLED(CONFIG_CFI_CLANG) || | |
171 | !IS_ENABLED(CONFIG_LTO_CLANG_THIN) || | |
172 | CONFIG_CLANG_VERSION >= 130000) | |
173 | return false; | |
174 | ||
175 | /* | |
176 | * Prior to LLVM 13, the following suffixes were observed when thinLTO | |
177 | * and CFI are both enabled: | |
178 | * - foo$[0-9]+ | |
179 | */ | |
8b8e6b5d | 180 | res = strrchr(s, '$'); |
6eb4bd92 | 181 | if (res) { |
8b8e6b5d | 182 | *res = '\0'; |
6eb4bd92 ND |
183 | return true; |
184 | } | |
8b8e6b5d | 185 | |
6eb4bd92 | 186 | return false; |
8b8e6b5d | 187 | } |
8b8e6b5d | 188 | |
1da177e4 LT |
189 | /* Lookup the address for this symbol. Returns 0 if not found. */ |
190 | unsigned long kallsyms_lookup_name(const char *name) | |
191 | { | |
9281acea | 192 | char namebuf[KSYM_NAME_LEN]; |
1da177e4 LT |
193 | unsigned long i; |
194 | unsigned int off; | |
195 | ||
aecf489f JO |
196 | /* Skip the search for empty string. */ |
197 | if (!*name) | |
198 | return 0; | |
199 | ||
1da177e4 | 200 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
e3f26752 | 201 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
1da177e4 LT |
202 | |
203 | if (strcmp(namebuf, name) == 0) | |
2213e9a6 | 204 | return kallsyms_sym_address(i); |
8b8e6b5d ST |
205 | |
206 | if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0) | |
207 | return kallsyms_sym_address(i); | |
1da177e4 LT |
208 | } |
209 | return module_kallsyms_lookup_name(name); | |
210 | } | |
1da177e4 | 211 | |
013c1667 CH |
212 | /* |
213 | * Iterate over all symbols in vmlinux. For symbols from modules use | |
214 | * module_kallsyms_on_each_symbol instead. | |
215 | */ | |
75a66614 AK |
216 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, |
217 | unsigned long), | |
218 | void *data) | |
219 | { | |
220 | char namebuf[KSYM_NAME_LEN]; | |
221 | unsigned long i; | |
222 | unsigned int off; | |
223 | int ret; | |
224 | ||
225 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
e3f26752 | 226 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
2213e9a6 | 227 | ret = fn(data, namebuf, NULL, kallsyms_sym_address(i)); |
75a66614 AK |
228 | if (ret != 0) |
229 | return ret; | |
f5bdb34b | 230 | cond_resched(); |
75a66614 | 231 | } |
013c1667 | 232 | return 0; |
75a66614 | 233 | } |
75a66614 | 234 | |
ffc50891 FBH |
235 | static unsigned long get_symbol_pos(unsigned long addr, |
236 | unsigned long *symbolsize, | |
237 | unsigned long *offset) | |
238 | { | |
239 | unsigned long symbol_start = 0, symbol_end = 0; | |
240 | unsigned long i, low, high, mid; | |
241 | ||
2ea03891 | 242 | /* This kernel should never had been booted. */ |
2213e9a6 AB |
243 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) |
244 | BUG_ON(!kallsyms_addresses); | |
245 | else | |
246 | BUG_ON(!kallsyms_offsets); | |
2ea03891 | 247 | |
ad6ccfad | 248 | /* Do a binary search on the sorted kallsyms_addresses array. */ |
ffc50891 FBH |
249 | low = 0; |
250 | high = kallsyms_num_syms; | |
251 | ||
252 | while (high - low > 1) { | |
2fc9c4e1 | 253 | mid = low + (high - low) / 2; |
2213e9a6 | 254 | if (kallsyms_sym_address(mid) <= addr) |
ffc50891 FBH |
255 | low = mid; |
256 | else | |
257 | high = mid; | |
258 | } | |
259 | ||
260 | /* | |
ad6ccfad MK |
261 | * Search for the first aliased symbol. Aliased |
262 | * symbols are symbols with the same address. | |
ffc50891 | 263 | */ |
2213e9a6 | 264 | while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low)) |
ffc50891 FBH |
265 | --low; |
266 | ||
2213e9a6 | 267 | symbol_start = kallsyms_sym_address(low); |
ffc50891 | 268 | |
ad6ccfad | 269 | /* Search for next non-aliased symbol. */ |
ffc50891 | 270 | for (i = low + 1; i < kallsyms_num_syms; i++) { |
2213e9a6 AB |
271 | if (kallsyms_sym_address(i) > symbol_start) { |
272 | symbol_end = kallsyms_sym_address(i); | |
ffc50891 FBH |
273 | break; |
274 | } | |
275 | } | |
276 | ||
ad6ccfad | 277 | /* If we found no next symbol, we use the end of the section. */ |
ffc50891 FBH |
278 | if (!symbol_end) { |
279 | if (is_kernel_inittext(addr)) | |
280 | symbol_end = (unsigned long)_einittext; | |
63b23e2c | 281 | else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) |
ffc50891 FBH |
282 | symbol_end = (unsigned long)_end; |
283 | else | |
284 | symbol_end = (unsigned long)_etext; | |
285 | } | |
286 | ||
ffb45122 AD |
287 | if (symbolsize) |
288 | *symbolsize = symbol_end - symbol_start; | |
289 | if (offset) | |
290 | *offset = addr - symbol_start; | |
ffc50891 FBH |
291 | |
292 | return low; | |
293 | } | |
294 | ||
295 | /* | |
296 | * Lookup an address but don't bother to find any names. | |
297 | */ | |
298 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, | |
299 | unsigned long *offset) | |
300 | { | |
6dd06c9f | 301 | char namebuf[KSYM_NAME_LEN]; |
74451e66 | 302 | |
2a1a3fa0 MZ |
303 | if (is_ksym_addr(addr)) { |
304 | get_symbol_pos(addr, symbolsize, offset); | |
305 | return 1; | |
306 | } | |
9294523e | 307 | return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) || |
74451e66 | 308 | !!__bpf_address_lookup(addr, symbolsize, offset, namebuf); |
ffc50891 FBH |
309 | } |
310 | ||
9294523e SB |
311 | static const char *kallsyms_lookup_buildid(unsigned long addr, |
312 | unsigned long *symbolsize, | |
313 | unsigned long *offset, char **modname, | |
314 | const unsigned char **modbuildid, char *namebuf) | |
1da177e4 | 315 | { |
74451e66 DB |
316 | const char *ret; |
317 | ||
9281acea | 318 | namebuf[KSYM_NAME_LEN - 1] = 0; |
1da177e4 LT |
319 | namebuf[0] = 0; |
320 | ||
ffc50891 FBH |
321 | if (is_ksym_addr(addr)) { |
322 | unsigned long pos; | |
1da177e4 | 323 | |
ffc50891 | 324 | pos = get_symbol_pos(addr, symbolsize, offset); |
1da177e4 | 325 | /* Grab name */ |
e3f26752 CG |
326 | kallsyms_expand_symbol(get_symbol_offset(pos), |
327 | namebuf, KSYM_NAME_LEN); | |
7a74fc49 KM |
328 | if (modname) |
329 | *modname = NULL; | |
9294523e SB |
330 | if (modbuildid) |
331 | *modbuildid = NULL; | |
8b8e6b5d ST |
332 | |
333 | ret = namebuf; | |
334 | goto found; | |
1da177e4 LT |
335 | } |
336 | ||
74451e66 DB |
337 | /* See if it's in a module or a BPF JITed image. */ |
338 | ret = module_address_lookup(addr, symbolsize, offset, | |
9294523e | 339 | modname, modbuildid, namebuf); |
74451e66 DB |
340 | if (!ret) |
341 | ret = bpf_address_lookup(addr, symbolsize, | |
342 | offset, modname, namebuf); | |
aba4b5c2 SRV |
343 | |
344 | if (!ret) | |
345 | ret = ftrace_mod_address_lookup(addr, symbolsize, | |
346 | offset, modname, namebuf); | |
8b8e6b5d ST |
347 | |
348 | found: | |
349 | cleanup_symbol_name(namebuf); | |
74451e66 | 350 | return ret; |
1da177e4 LT |
351 | } |
352 | ||
9294523e SB |
353 | /* |
354 | * Lookup an address | |
355 | * - modname is set to NULL if it's in the kernel. | |
356 | * - We guarantee that the returned name is valid until we reschedule even if. | |
357 | * It resides in a module. | |
358 | * - We also guarantee that modname will be valid until rescheduled. | |
359 | */ | |
360 | const char *kallsyms_lookup(unsigned long addr, | |
361 | unsigned long *symbolsize, | |
362 | unsigned long *offset, | |
363 | char **modname, char *namebuf) | |
364 | { | |
365 | return kallsyms_lookup_buildid(addr, symbolsize, offset, modname, | |
366 | NULL, namebuf); | |
367 | } | |
368 | ||
9d65cb4a AD |
369 | int lookup_symbol_name(unsigned long addr, char *symname) |
370 | { | |
8b8e6b5d ST |
371 | int res; |
372 | ||
9d65cb4a | 373 | symname[0] = '\0'; |
9281acea | 374 | symname[KSYM_NAME_LEN - 1] = '\0'; |
9d65cb4a AD |
375 | |
376 | if (is_ksym_addr(addr)) { | |
377 | unsigned long pos; | |
378 | ||
379 | pos = get_symbol_pos(addr, NULL, NULL); | |
380 | /* Grab name */ | |
e3f26752 CG |
381 | kallsyms_expand_symbol(get_symbol_offset(pos), |
382 | symname, KSYM_NAME_LEN); | |
8b8e6b5d | 383 | goto found; |
9d65cb4a | 384 | } |
ad6ccfad | 385 | /* See if it's in a module. */ |
8b8e6b5d ST |
386 | res = lookup_module_symbol_name(addr, symname); |
387 | if (res) | |
388 | return res; | |
389 | ||
390 | found: | |
391 | cleanup_symbol_name(symname); | |
392 | return 0; | |
9d65cb4a AD |
393 | } |
394 | ||
a5c43dae AD |
395 | int lookup_symbol_attrs(unsigned long addr, unsigned long *size, |
396 | unsigned long *offset, char *modname, char *name) | |
397 | { | |
8b8e6b5d ST |
398 | int res; |
399 | ||
a5c43dae | 400 | name[0] = '\0'; |
9281acea | 401 | name[KSYM_NAME_LEN - 1] = '\0'; |
a5c43dae AD |
402 | |
403 | if (is_ksym_addr(addr)) { | |
404 | unsigned long pos; | |
405 | ||
406 | pos = get_symbol_pos(addr, size, offset); | |
407 | /* Grab name */ | |
e3f26752 CG |
408 | kallsyms_expand_symbol(get_symbol_offset(pos), |
409 | name, KSYM_NAME_LEN); | |
a5c43dae | 410 | modname[0] = '\0'; |
8b8e6b5d | 411 | goto found; |
a5c43dae | 412 | } |
ad6ccfad | 413 | /* See if it's in a module. */ |
8b8e6b5d ST |
414 | res = lookup_module_symbol_attrs(addr, size, offset, modname, name); |
415 | if (res) | |
416 | return res; | |
417 | ||
418 | found: | |
419 | cleanup_symbol_name(name); | |
420 | return 0; | |
a5c43dae AD |
421 | } |
422 | ||
42e38083 | 423 | /* Look up a kernel symbol and return it in a text buffer. */ |
0f77a8d3 | 424 | static int __sprint_symbol(char *buffer, unsigned long address, |
9294523e | 425 | int symbol_offset, int add_offset, int add_buildid) |
1da177e4 LT |
426 | { |
427 | char *modname; | |
9294523e | 428 | const unsigned char *buildid; |
1da177e4 LT |
429 | const char *name; |
430 | unsigned long offset, size; | |
966c8c12 | 431 | int len; |
1da177e4 | 432 | |
0f77a8d3 | 433 | address += symbol_offset; |
9294523e SB |
434 | name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid, |
435 | buffer); | |
1da177e4 | 436 | if (!name) |
b86280aa | 437 | return sprintf(buffer, "0x%lx", address - symbol_offset); |
19769b76 | 438 | |
966c8c12 HD |
439 | if (name != buffer) |
440 | strcpy(buffer, name); | |
441 | len = strlen(buffer); | |
0f77a8d3 | 442 | offset -= symbol_offset; |
966c8c12 | 443 | |
4796dd20 SB |
444 | if (add_offset) |
445 | len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); | |
446 | ||
9294523e SB |
447 | if (modname) { |
448 | len += sprintf(buffer + len, " [%s", modname); | |
449 | #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) | |
450 | if (add_buildid && buildid) { | |
451 | /* build ID should match length of sprintf */ | |
452 | #if IS_ENABLED(CONFIG_MODULES) | |
453 | static_assert(sizeof(typeof_member(struct module, build_id)) == 20); | |
454 | #endif | |
455 | len += sprintf(buffer + len, " %20phN", buildid); | |
456 | } | |
457 | #endif | |
458 | len += sprintf(buffer + len, "]"); | |
459 | } | |
966c8c12 HD |
460 | |
461 | return len; | |
42e38083 | 462 | } |
0f77a8d3 NK |
463 | |
464 | /** | |
465 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer | |
466 | * @buffer: buffer to be stored | |
467 | * @address: address to lookup | |
468 | * | |
469 | * This function looks up a kernel symbol with @address and stores its name, | |
470 | * offset, size and module name to @buffer if possible. If no symbol was found, | |
471 | * just saves its @address as is. | |
472 | * | |
473 | * This function returns the number of bytes stored in @buffer. | |
474 | */ | |
475 | int sprint_symbol(char *buffer, unsigned long address) | |
476 | { | |
9294523e | 477 | return __sprint_symbol(buffer, address, 0, 1, 0); |
0f77a8d3 | 478 | } |
ad6ccfad | 479 | EXPORT_SYMBOL_GPL(sprint_symbol); |
42e38083 | 480 | |
9294523e SB |
481 | /** |
482 | * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer | |
483 | * @buffer: buffer to be stored | |
484 | * @address: address to lookup | |
485 | * | |
486 | * This function looks up a kernel symbol with @address and stores its name, | |
487 | * offset, size, module name and module build ID to @buffer if possible. If no | |
488 | * symbol was found, just saves its @address as is. | |
489 | * | |
490 | * This function returns the number of bytes stored in @buffer. | |
491 | */ | |
492 | int sprint_symbol_build_id(char *buffer, unsigned long address) | |
493 | { | |
494 | return __sprint_symbol(buffer, address, 0, 1, 1); | |
495 | } | |
496 | EXPORT_SYMBOL_GPL(sprint_symbol_build_id); | |
497 | ||
4796dd20 SB |
498 | /** |
499 | * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer | |
500 | * @buffer: buffer to be stored | |
501 | * @address: address to lookup | |
502 | * | |
503 | * This function looks up a kernel symbol with @address and stores its name | |
504 | * and module name to @buffer if possible. If no symbol was found, just saves | |
505 | * its @address as is. | |
506 | * | |
507 | * This function returns the number of bytes stored in @buffer. | |
508 | */ | |
509 | int sprint_symbol_no_offset(char *buffer, unsigned long address) | |
510 | { | |
9294523e | 511 | return __sprint_symbol(buffer, address, 0, 0, 0); |
4796dd20 SB |
512 | } |
513 | EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); | |
514 | ||
0f77a8d3 NK |
515 | /** |
516 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer | |
517 | * @buffer: buffer to be stored | |
518 | * @address: address to lookup | |
519 | * | |
520 | * This function is for stack backtrace and does the same thing as | |
521 | * sprint_symbol() but with modified/decreased @address. If there is a | |
522 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
523 | * the call so that the stack-saved return address could point outside of the | |
524 | * caller. This function ensures that kallsyms will find the original caller | |
525 | * by decreasing @address. | |
526 | * | |
527 | * This function returns the number of bytes stored in @buffer. | |
528 | */ | |
529 | int sprint_backtrace(char *buffer, unsigned long address) | |
530 | { | |
9294523e SB |
531 | return __sprint_symbol(buffer, address, -1, 1, 0); |
532 | } | |
533 | ||
534 | /** | |
535 | * sprint_backtrace_build_id - 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. This function also appends the module build ID to | |
545 | * the @buffer if @address is within a kernel module. | |
546 | * | |
547 | * This function returns the number of bytes stored in @buffer. | |
548 | */ | |
549 | int sprint_backtrace_build_id(char *buffer, unsigned long address) | |
550 | { | |
551 | return __sprint_symbol(buffer, address, -1, 1, 1); | |
0f77a8d3 NK |
552 | } |
553 | ||
1da177e4 | 554 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ |
ad6ccfad | 555 | struct kallsym_iter { |
1da177e4 | 556 | loff_t pos; |
d83212d5 | 557 | loff_t pos_arch_end; |
74451e66 | 558 | loff_t pos_mod_end; |
6171a031 | 559 | loff_t pos_ftrace_mod_end; |
d002b8bc | 560 | loff_t pos_bpf_end; |
1da177e4 | 561 | unsigned long value; |
ad6ccfad | 562 | unsigned int nameoff; /* If iterating in core kernel symbols. */ |
1da177e4 | 563 | char type; |
9281acea TH |
564 | char name[KSYM_NAME_LEN]; |
565 | char module_name[MODULE_NAME_LEN]; | |
ea07890a | 566 | int exported; |
c0f3ea15 | 567 | int show_value; |
1da177e4 LT |
568 | }; |
569 | ||
d83212d5 AS |
570 | int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value, |
571 | char *type, char *name) | |
572 | { | |
573 | return -EINVAL; | |
574 | } | |
575 | ||
576 | static int get_ksymbol_arch(struct kallsym_iter *iter) | |
577 | { | |
578 | int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms, | |
579 | &iter->value, &iter->type, | |
580 | iter->name); | |
581 | ||
582 | if (ret < 0) { | |
583 | iter->pos_arch_end = iter->pos; | |
584 | return 0; | |
585 | } | |
586 | ||
587 | return 1; | |
588 | } | |
589 | ||
1da177e4 LT |
590 | static int get_ksymbol_mod(struct kallsym_iter *iter) |
591 | { | |
d83212d5 | 592 | int ret = module_get_kallsym(iter->pos - iter->pos_arch_end, |
74451e66 DB |
593 | &iter->value, &iter->type, |
594 | iter->name, iter->module_name, | |
595 | &iter->exported); | |
596 | if (ret < 0) { | |
597 | iter->pos_mod_end = iter->pos; | |
1da177e4 | 598 | return 0; |
74451e66 DB |
599 | } |
600 | ||
1da177e4 LT |
601 | return 1; |
602 | } | |
603 | ||
fc0ea795 AH |
604 | /* |
605 | * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace | |
606 | * purposes. In that case "__builtin__ftrace" is used as a module name, even | |
607 | * though "__builtin__ftrace" is not a module. | |
608 | */ | |
6171a031 SRV |
609 | static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter) |
610 | { | |
611 | int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end, | |
612 | &iter->value, &iter->type, | |
613 | iter->name, iter->module_name, | |
614 | &iter->exported); | |
615 | if (ret < 0) { | |
616 | iter->pos_ftrace_mod_end = iter->pos; | |
617 | return 0; | |
618 | } | |
619 | ||
620 | return 1; | |
621 | } | |
622 | ||
74451e66 DB |
623 | static int get_ksymbol_bpf(struct kallsym_iter *iter) |
624 | { | |
d002b8bc AH |
625 | int ret; |
626 | ||
6934058d | 627 | strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN); |
74451e66 | 628 | iter->exported = 0; |
d002b8bc AH |
629 | ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end, |
630 | &iter->value, &iter->type, | |
631 | iter->name); | |
632 | if (ret < 0) { | |
633 | iter->pos_bpf_end = iter->pos; | |
634 | return 0; | |
635 | } | |
636 | ||
637 | return 1; | |
638 | } | |
639 | ||
640 | /* | |
641 | * This uses "__builtin__kprobes" as a module name for symbols for pages | |
642 | * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a | |
643 | * module. | |
644 | */ | |
645 | static int get_ksymbol_kprobe(struct kallsym_iter *iter) | |
646 | { | |
647 | strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN); | |
648 | iter->exported = 0; | |
649 | return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end, | |
650 | &iter->value, &iter->type, | |
651 | iter->name) < 0 ? 0 : 1; | |
74451e66 DB |
652 | } |
653 | ||
1da177e4 LT |
654 | /* Returns space to next name. */ |
655 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
656 | { | |
657 | unsigned off = iter->nameoff; | |
658 | ||
ea07890a | 659 | iter->module_name[0] = '\0'; |
2213e9a6 | 660 | iter->value = kallsyms_sym_address(iter->pos); |
1da177e4 LT |
661 | |
662 | iter->type = kallsyms_get_symbol_type(off); | |
663 | ||
e3f26752 | 664 | off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name)); |
1da177e4 LT |
665 | |
666 | return off - iter->nameoff; | |
667 | } | |
668 | ||
669 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
670 | { | |
671 | iter->name[0] = '\0'; | |
672 | iter->nameoff = get_symbol_offset(new_pos); | |
673 | iter->pos = new_pos; | |
6171a031 | 674 | if (new_pos == 0) { |
d83212d5 | 675 | iter->pos_arch_end = 0; |
74451e66 | 676 | iter->pos_mod_end = 0; |
6171a031 | 677 | iter->pos_ftrace_mod_end = 0; |
d002b8bc | 678 | iter->pos_bpf_end = 0; |
6171a031 | 679 | } |
74451e66 DB |
680 | } |
681 | ||
b9667942 AH |
682 | /* |
683 | * The end position (last + 1) of each additional kallsyms section is recorded | |
684 | * in iter->pos_..._end as each section is added, and so can be used to | |
685 | * determine which get_ksymbol_...() function to call next. | |
686 | */ | |
74451e66 DB |
687 | static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) |
688 | { | |
689 | iter->pos = pos; | |
690 | ||
d83212d5 AS |
691 | if ((!iter->pos_arch_end || iter->pos_arch_end > pos) && |
692 | get_ksymbol_arch(iter)) | |
693 | return 1; | |
694 | ||
b9667942 AH |
695 | if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && |
696 | get_ksymbol_mod(iter)) | |
6171a031 | 697 | return 1; |
6171a031 | 698 | |
b9667942 AH |
699 | if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) && |
700 | get_ksymbol_ftrace_mod(iter)) | |
701 | return 1; | |
74451e66 | 702 | |
d002b8bc AH |
703 | if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) && |
704 | get_ksymbol_bpf(iter)) | |
705 | return 1; | |
706 | ||
707 | return get_ksymbol_kprobe(iter); | |
1da177e4 LT |
708 | } |
709 | ||
710 | /* Returns false if pos at or past end of file. */ | |
711 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
712 | { | |
713 | /* Module symbols can be accessed randomly. */ | |
74451e66 DB |
714 | if (pos >= kallsyms_num_syms) |
715 | return update_iter_mod(iter, pos); | |
ad6ccfad | 716 | |
1da177e4 LT |
717 | /* If we're not on the desired position, reset to new position. */ |
718 | if (pos != iter->pos) | |
719 | reset_iter(iter, pos); | |
720 | ||
721 | iter->nameoff += get_ksymbol_core(iter); | |
722 | iter->pos++; | |
723 | ||
724 | return 1; | |
725 | } | |
726 | ||
727 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
728 | { | |
729 | (*pos)++; | |
730 | ||
731 | if (!update_iter(m->private, *pos)) | |
732 | return NULL; | |
733 | return p; | |
734 | } | |
735 | ||
736 | static void *s_start(struct seq_file *m, loff_t *pos) | |
737 | { | |
738 | if (!update_iter(m->private, *pos)) | |
739 | return NULL; | |
740 | return m->private; | |
741 | } | |
742 | ||
743 | static void s_stop(struct seq_file *m, void *p) | |
744 | { | |
745 | } | |
746 | ||
747 | static int s_show(struct seq_file *m, void *p) | |
748 | { | |
668533dc | 749 | void *value; |
1da177e4 LT |
750 | struct kallsym_iter *iter = m->private; |
751 | ||
ad6ccfad | 752 | /* Some debugging symbols have no name. Ignore them. */ |
1da177e4 LT |
753 | if (!iter->name[0]) |
754 | return 0; | |
755 | ||
668533dc | 756 | value = iter->show_value ? (void *)iter->value : NULL; |
c0f3ea15 | 757 | |
ea07890a AD |
758 | if (iter->module_name[0]) { |
759 | char type; | |
760 | ||
ad6ccfad MK |
761 | /* |
762 | * Label it "global" if it is exported, | |
763 | * "local" if not exported. | |
764 | */ | |
ea07890a AD |
765 | type = iter->exported ? toupper(iter->type) : |
766 | tolower(iter->type); | |
668533dc | 767 | seq_printf(m, "%px %c %s\t[%s]\n", value, |
9f36e2c4 | 768 | type, iter->name, iter->module_name); |
ea07890a | 769 | } else |
668533dc | 770 | seq_printf(m, "%px %c %s\n", value, |
9f36e2c4 | 771 | iter->type, iter->name); |
1da177e4 LT |
772 | return 0; |
773 | } | |
774 | ||
15ad7cdc | 775 | static const struct seq_operations kallsyms_op = { |
1da177e4 LT |
776 | .start = s_start, |
777 | .next = s_next, | |
778 | .stop = s_stop, | |
779 | .show = s_show | |
780 | }; | |
781 | ||
647cafa2 AM |
782 | #ifdef CONFIG_BPF_SYSCALL |
783 | ||
784 | struct bpf_iter__ksym { | |
785 | __bpf_md_ptr(struct bpf_iter_meta *, meta); | |
786 | __bpf_md_ptr(struct kallsym_iter *, ksym); | |
787 | }; | |
788 | ||
789 | static int ksym_prog_seq_show(struct seq_file *m, bool in_stop) | |
790 | { | |
791 | struct bpf_iter__ksym ctx; | |
792 | struct bpf_iter_meta meta; | |
793 | struct bpf_prog *prog; | |
794 | ||
795 | meta.seq = m; | |
796 | prog = bpf_iter_get_info(&meta, in_stop); | |
797 | if (!prog) | |
798 | return 0; | |
799 | ||
800 | ctx.meta = &meta; | |
801 | ctx.ksym = m ? m->private : NULL; | |
802 | return bpf_iter_run_prog(prog, &ctx); | |
803 | } | |
804 | ||
805 | static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p) | |
806 | { | |
807 | return ksym_prog_seq_show(m, false); | |
808 | } | |
809 | ||
810 | static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p) | |
811 | { | |
812 | if (!p) | |
813 | (void) ksym_prog_seq_show(m, true); | |
814 | else | |
815 | s_stop(m, p); | |
816 | } | |
817 | ||
818 | static const struct seq_operations bpf_iter_ksym_ops = { | |
819 | .start = s_start, | |
820 | .next = s_next, | |
821 | .stop = bpf_iter_ksym_seq_stop, | |
822 | .show = bpf_iter_ksym_seq_show, | |
823 | }; | |
824 | ||
825 | static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux) | |
826 | { | |
827 | struct kallsym_iter *iter = priv_data; | |
828 | ||
829 | reset_iter(iter, 0); | |
830 | ||
831 | /* cache here as in kallsyms_open() case; use current process | |
832 | * credentials to tell BPF iterators if values should be shown. | |
833 | */ | |
834 | iter->show_value = kallsyms_show_value(current_cred()); | |
835 | ||
836 | return 0; | |
837 | } | |
838 | ||
839 | DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym) | |
840 | ||
841 | static const struct bpf_iter_seq_info ksym_iter_seq_info = { | |
842 | .seq_ops = &bpf_iter_ksym_ops, | |
843 | .init_seq_private = bpf_iter_ksym_init, | |
844 | .fini_seq_private = NULL, | |
845 | .seq_priv_size = sizeof(struct kallsym_iter), | |
846 | }; | |
847 | ||
848 | static struct bpf_iter_reg ksym_iter_reg_info = { | |
849 | .target = "ksym", | |
850 | .feature = BPF_ITER_RESCHED, | |
851 | .ctx_arg_info_size = 1, | |
852 | .ctx_arg_info = { | |
853 | { offsetof(struct bpf_iter__ksym, ksym), | |
854 | PTR_TO_BTF_ID_OR_NULL }, | |
855 | }, | |
856 | .seq_info = &ksym_iter_seq_info, | |
857 | }; | |
858 | ||
859 | BTF_ID_LIST(btf_ksym_iter_id) | |
860 | BTF_ID(struct, kallsym_iter) | |
861 | ||
862 | static int __init bpf_ksym_iter_register(void) | |
863 | { | |
864 | ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id; | |
865 | return bpf_iter_reg_target(&ksym_iter_reg_info); | |
866 | } | |
867 | ||
868 | late_initcall(bpf_ksym_iter_register); | |
869 | ||
870 | #endif /* CONFIG_BPF_SYSCALL */ | |
871 | ||
c0f3ea15 LT |
872 | static inline int kallsyms_for_perf(void) |
873 | { | |
874 | #ifdef CONFIG_PERF_EVENTS | |
875 | extern int sysctl_perf_event_paranoid; | |
876 | if (sysctl_perf_event_paranoid <= 1) | |
877 | return 1; | |
878 | #endif | |
879 | return 0; | |
880 | } | |
881 | ||
882 | /* | |
883 | * We show kallsyms information even to normal users if we've enabled | |
884 | * kernel profiling and are explicitly not paranoid (so kptr_restrict | |
885 | * is clear, and sysctl_perf_event_paranoid isn't set). | |
886 | * | |
887 | * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to | |
888 | * block even that). | |
889 | */ | |
16025184 | 890 | bool kallsyms_show_value(const struct cred *cred) |
c0f3ea15 LT |
891 | { |
892 | switch (kptr_restrict) { | |
893 | case 0: | |
894 | if (kallsyms_for_perf()) | |
16025184 | 895 | return true; |
df561f66 | 896 | fallthrough; |
c0f3ea15 | 897 | case 1: |
16025184 KC |
898 | if (security_capable(cred, &init_user_ns, CAP_SYSLOG, |
899 | CAP_OPT_NOAUDIT) == 0) | |
900 | return true; | |
df561f66 | 901 | fallthrough; |
c0f3ea15 | 902 | default: |
16025184 | 903 | return false; |
c0f3ea15 LT |
904 | } |
905 | } | |
906 | ||
1da177e4 LT |
907 | static int kallsyms_open(struct inode *inode, struct file *file) |
908 | { | |
ad6ccfad MK |
909 | /* |
910 | * We keep iterator in m->private, since normal case is to | |
1da177e4 | 911 | * s_start from where we left off, so we avoid doing |
ad6ccfad MK |
912 | * using get_symbol_offset for every symbol. |
913 | */ | |
1da177e4 | 914 | struct kallsym_iter *iter; |
0049f26a | 915 | iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter)); |
1da177e4 LT |
916 | if (!iter) |
917 | return -ENOMEM; | |
918 | reset_iter(iter, 0); | |
919 | ||
16025184 KC |
920 | /* |
921 | * Instead of checking this on every s_show() call, cache | |
922 | * the result here at open time. | |
923 | */ | |
924 | iter->show_value = kallsyms_show_value(file->f_cred); | |
0049f26a | 925 | return 0; |
1da177e4 LT |
926 | } |
927 | ||
67fc4e0c JW |
928 | #ifdef CONFIG_KGDB_KDB |
929 | const char *kdb_walk_kallsyms(loff_t *pos) | |
930 | { | |
931 | static struct kallsym_iter kdb_walk_kallsyms_iter; | |
932 | if (*pos == 0) { | |
933 | memset(&kdb_walk_kallsyms_iter, 0, | |
934 | sizeof(kdb_walk_kallsyms_iter)); | |
935 | reset_iter(&kdb_walk_kallsyms_iter, 0); | |
936 | } | |
937 | while (1) { | |
938 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) | |
939 | return NULL; | |
940 | ++*pos; | |
941 | /* Some debugging symbols have no name. Ignore them. */ | |
942 | if (kdb_walk_kallsyms_iter.name[0]) | |
943 | return kdb_walk_kallsyms_iter.name; | |
944 | } | |
945 | } | |
946 | #endif /* CONFIG_KGDB_KDB */ | |
947 | ||
97a32539 AD |
948 | static const struct proc_ops kallsyms_proc_ops = { |
949 | .proc_open = kallsyms_open, | |
950 | .proc_read = seq_read, | |
951 | .proc_lseek = seq_lseek, | |
952 | .proc_release = seq_release_private, | |
1da177e4 LT |
953 | }; |
954 | ||
955 | static int __init kallsyms_init(void) | |
956 | { | |
97a32539 | 957 | proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops); |
1da177e4 LT |
958 | return 0; |
959 | } | |
ad6ccfad | 960 | device_initcall(kallsyms_init); |