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