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 | |
ad6ccfad MK |
35 | /* |
36 | * These will be re-linked against their real values | |
37 | * during the second link stage. | |
38 | */ | |
52f5684c | 39 | extern const unsigned long kallsyms_addresses[] __weak; |
2213e9a6 | 40 | extern const int kallsyms_offsets[] __weak; |
52f5684c | 41 | extern const u8 kallsyms_names[] __weak; |
1da177e4 | 42 | |
ad6ccfad MK |
43 | /* |
44 | * Tell the compiler that the count isn't in the small data section if the arch | |
45 | * has one (eg: FRV). | |
9e6c1e63 | 46 | */ |
80ffbaa5 | 47 | extern const unsigned int kallsyms_num_syms |
33def849 | 48 | __section(".rodata") __attribute__((weak)); |
9e6c1e63 | 49 | |
2213e9a6 | 50 | extern const unsigned long kallsyms_relative_base |
33def849 | 51 | __section(".rodata") __attribute__((weak)); |
2213e9a6 | 52 | |
cde26a6e | 53 | extern const char kallsyms_token_table[] __weak; |
52f5684c | 54 | extern const u16 kallsyms_token_index[] __weak; |
1da177e4 | 55 | |
80ffbaa5 | 56 | extern const unsigned int kallsyms_markers[] __weak; |
1da177e4 | 57 | |
ad6ccfad MK |
58 | /* |
59 | * Expand a compressed symbol data into the resulting uncompressed string, | |
e3f26752 | 60 | * if uncompressed string is too long (>= maxlen), it will be truncated, |
ad6ccfad MK |
61 | * given the offset to where the symbol is in the compressed stream. |
62 | */ | |
e3f26752 CG |
63 | static unsigned int kallsyms_expand_symbol(unsigned int off, |
64 | char *result, size_t maxlen) | |
1da177e4 LT |
65 | { |
66 | int len, skipped_first = 0; | |
cde26a6e MY |
67 | const char *tptr; |
68 | const u8 *data; | |
1da177e4 | 69 | |
ad6ccfad | 70 | /* Get the compressed symbol length from the first symbol byte. */ |
1da177e4 LT |
71 | data = &kallsyms_names[off]; |
72 | len = *data; | |
73 | data++; | |
74 | ||
ad6ccfad MK |
75 | /* |
76 | * Update the offset to return the offset for the next symbol on | |
77 | * the compressed stream. | |
78 | */ | |
1da177e4 LT |
79 | off += len + 1; |
80 | ||
ad6ccfad MK |
81 | /* |
82 | * For every byte on the compressed symbol data, copy the table | |
83 | * entry for that byte. | |
84 | */ | |
85 | while (len) { | |
86 | tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; | |
1da177e4 LT |
87 | data++; |
88 | len--; | |
89 | ||
90 | while (*tptr) { | |
ad6ccfad | 91 | if (skipped_first) { |
e3f26752 CG |
92 | if (maxlen <= 1) |
93 | goto tail; | |
1da177e4 LT |
94 | *result = *tptr; |
95 | result++; | |
e3f26752 | 96 | maxlen--; |
1da177e4 LT |
97 | } else |
98 | skipped_first = 1; | |
99 | tptr++; | |
100 | } | |
101 | } | |
102 | ||
e3f26752 CG |
103 | tail: |
104 | if (maxlen) | |
105 | *result = '\0'; | |
1da177e4 | 106 | |
ad6ccfad | 107 | /* Return to offset to the next symbol. */ |
1da177e4 LT |
108 | return off; |
109 | } | |
110 | ||
ad6ccfad MK |
111 | /* |
112 | * Get symbol type information. This is encoded as a single char at the | |
113 | * beginning of the symbol name. | |
114 | */ | |
1da177e4 LT |
115 | static char kallsyms_get_symbol_type(unsigned int off) |
116 | { | |
ad6ccfad MK |
117 | /* |
118 | * Get just the first code, look it up in the token table, | |
119 | * and return the first char from this token. | |
120 | */ | |
121 | return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; | |
1da177e4 LT |
122 | } |
123 | ||
124 | ||
ad6ccfad MK |
125 | /* |
126 | * Find the offset on the compressed stream given and index in the | |
127 | * kallsyms array. | |
128 | */ | |
1da177e4 LT |
129 | static unsigned int get_symbol_offset(unsigned long pos) |
130 | { | |
aad09470 | 131 | const u8 *name; |
1da177e4 LT |
132 | int i; |
133 | ||
ad6ccfad MK |
134 | /* |
135 | * Use the closest marker we have. We have markers every 256 positions, | |
136 | * so that should be close enough. | |
137 | */ | |
138 | name = &kallsyms_names[kallsyms_markers[pos >> 8]]; | |
1da177e4 | 139 | |
ad6ccfad MK |
140 | /* |
141 | * Sequentially scan all the symbols up to the point we're searching | |
142 | * for. Every symbol is stored in a [<len>][<len> bytes of data] format, | |
143 | * so we just need to add the len to the current pointer for every | |
144 | * symbol we wish to skip. | |
145 | */ | |
146 | for (i = 0; i < (pos & 0xFF); i++) | |
1da177e4 LT |
147 | name = name + (*name) + 1; |
148 | ||
149 | return name - kallsyms_names; | |
150 | } | |
151 | ||
2213e9a6 AB |
152 | static unsigned long kallsyms_sym_address(int idx) |
153 | { | |
154 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) | |
155 | return kallsyms_addresses[idx]; | |
156 | ||
157 | /* values are unsigned offsets if --absolute-percpu is not in effect */ | |
158 | if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU)) | |
159 | return kallsyms_relative_base + (u32)kallsyms_offsets[idx]; | |
160 | ||
161 | /* ...otherwise, positive offsets are absolute values */ | |
162 | if (kallsyms_offsets[idx] >= 0) | |
163 | return kallsyms_offsets[idx]; | |
164 | ||
165 | /* ...and negative offsets are relative to kallsyms_relative_base - 1 */ | |
166 | return kallsyms_relative_base - 1 - kallsyms_offsets[idx]; | |
167 | } | |
168 | ||
6eb4bd92 | 169 | static bool cleanup_symbol_name(char *s) |
8b8e6b5d ST |
170 | { |
171 | char *res; | |
172 | ||
6eb4bd92 ND |
173 | if (!IS_ENABLED(CONFIG_LTO_CLANG)) |
174 | return false; | |
175 | ||
176 | /* | |
177 | * LLVM appends various suffixes for local functions and variables that | |
178 | * must be promoted to global scope as part of LTO. This can break | |
179 | * hooking of static functions with kprobes. '.' is not a valid | |
180 | * character in an identifier in C. Suffixes observed: | |
181 | * - foo.llvm.[0-9a-f]+ | |
182 | * - foo.[0-9a-f]+ | |
183 | * - foo.[0-9a-f]+.cfi_jt | |
184 | */ | |
185 | res = strchr(s, '.'); | |
186 | if (res) { | |
187 | *res = '\0'; | |
188 | return true; | |
189 | } | |
190 | ||
191 | if (!IS_ENABLED(CONFIG_CFI_CLANG) || | |
192 | !IS_ENABLED(CONFIG_LTO_CLANG_THIN) || | |
193 | CONFIG_CLANG_VERSION >= 130000) | |
194 | return false; | |
195 | ||
196 | /* | |
197 | * Prior to LLVM 13, the following suffixes were observed when thinLTO | |
198 | * and CFI are both enabled: | |
199 | * - foo$[0-9]+ | |
200 | */ | |
8b8e6b5d | 201 | res = strrchr(s, '$'); |
6eb4bd92 | 202 | if (res) { |
8b8e6b5d | 203 | *res = '\0'; |
6eb4bd92 ND |
204 | return true; |
205 | } | |
8b8e6b5d | 206 | |
6eb4bd92 | 207 | return false; |
8b8e6b5d | 208 | } |
8b8e6b5d | 209 | |
1da177e4 LT |
210 | /* Lookup the address for this symbol. Returns 0 if not found. */ |
211 | unsigned long kallsyms_lookup_name(const char *name) | |
212 | { | |
9281acea | 213 | char namebuf[KSYM_NAME_LEN]; |
1da177e4 LT |
214 | unsigned long i; |
215 | unsigned int off; | |
216 | ||
aecf489f JO |
217 | /* Skip the search for empty string. */ |
218 | if (!*name) | |
219 | return 0; | |
220 | ||
1da177e4 | 221 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
e3f26752 | 222 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
1da177e4 LT |
223 | |
224 | if (strcmp(namebuf, name) == 0) | |
2213e9a6 | 225 | return kallsyms_sym_address(i); |
8b8e6b5d ST |
226 | |
227 | if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0) | |
228 | return kallsyms_sym_address(i); | |
1da177e4 LT |
229 | } |
230 | return module_kallsyms_lookup_name(name); | |
231 | } | |
1da177e4 | 232 | |
013c1667 CH |
233 | /* |
234 | * Iterate over all symbols in vmlinux. For symbols from modules use | |
235 | * module_kallsyms_on_each_symbol instead. | |
236 | */ | |
75a66614 AK |
237 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, |
238 | unsigned long), | |
239 | void *data) | |
240 | { | |
241 | char namebuf[KSYM_NAME_LEN]; | |
242 | unsigned long i; | |
243 | unsigned int off; | |
244 | int ret; | |
245 | ||
246 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
e3f26752 | 247 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
2213e9a6 | 248 | ret = fn(data, namebuf, NULL, kallsyms_sym_address(i)); |
75a66614 AK |
249 | if (ret != 0) |
250 | return ret; | |
f5bdb34b | 251 | cond_resched(); |
75a66614 | 252 | } |
013c1667 | 253 | return 0; |
75a66614 | 254 | } |
75a66614 | 255 | |
ffc50891 FBH |
256 | static unsigned long get_symbol_pos(unsigned long addr, |
257 | unsigned long *symbolsize, | |
258 | unsigned long *offset) | |
259 | { | |
260 | unsigned long symbol_start = 0, symbol_end = 0; | |
261 | unsigned long i, low, high, mid; | |
262 | ||
2ea03891 | 263 | /* This kernel should never had been booted. */ |
2213e9a6 AB |
264 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) |
265 | BUG_ON(!kallsyms_addresses); | |
266 | else | |
267 | BUG_ON(!kallsyms_offsets); | |
2ea03891 | 268 | |
ad6ccfad | 269 | /* Do a binary search on the sorted kallsyms_addresses array. */ |
ffc50891 FBH |
270 | low = 0; |
271 | high = kallsyms_num_syms; | |
272 | ||
273 | while (high - low > 1) { | |
2fc9c4e1 | 274 | mid = low + (high - low) / 2; |
2213e9a6 | 275 | if (kallsyms_sym_address(mid) <= addr) |
ffc50891 FBH |
276 | low = mid; |
277 | else | |
278 | high = mid; | |
279 | } | |
280 | ||
281 | /* | |
ad6ccfad MK |
282 | * Search for the first aliased symbol. Aliased |
283 | * symbols are symbols with the same address. | |
ffc50891 | 284 | */ |
2213e9a6 | 285 | while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low)) |
ffc50891 FBH |
286 | --low; |
287 | ||
2213e9a6 | 288 | symbol_start = kallsyms_sym_address(low); |
ffc50891 | 289 | |
ad6ccfad | 290 | /* Search for next non-aliased symbol. */ |
ffc50891 | 291 | for (i = low + 1; i < kallsyms_num_syms; i++) { |
2213e9a6 AB |
292 | if (kallsyms_sym_address(i) > symbol_start) { |
293 | symbol_end = kallsyms_sym_address(i); | |
ffc50891 FBH |
294 | break; |
295 | } | |
296 | } | |
297 | ||
ad6ccfad | 298 | /* If we found no next symbol, we use the end of the section. */ |
ffc50891 FBH |
299 | if (!symbol_end) { |
300 | if (is_kernel_inittext(addr)) | |
301 | symbol_end = (unsigned long)_einittext; | |
63b23e2c | 302 | else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) |
ffc50891 FBH |
303 | symbol_end = (unsigned long)_end; |
304 | else | |
305 | symbol_end = (unsigned long)_etext; | |
306 | } | |
307 | ||
ffb45122 AD |
308 | if (symbolsize) |
309 | *symbolsize = symbol_end - symbol_start; | |
310 | if (offset) | |
311 | *offset = addr - symbol_start; | |
ffc50891 FBH |
312 | |
313 | return low; | |
314 | } | |
315 | ||
316 | /* | |
317 | * Lookup an address but don't bother to find any names. | |
318 | */ | |
319 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, | |
320 | unsigned long *offset) | |
321 | { | |
6dd06c9f | 322 | char namebuf[KSYM_NAME_LEN]; |
74451e66 | 323 | |
2a1a3fa0 MZ |
324 | if (is_ksym_addr(addr)) { |
325 | get_symbol_pos(addr, symbolsize, offset); | |
326 | return 1; | |
327 | } | |
9294523e | 328 | return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) || |
74451e66 | 329 | !!__bpf_address_lookup(addr, symbolsize, offset, namebuf); |
ffc50891 FBH |
330 | } |
331 | ||
9294523e SB |
332 | static const char *kallsyms_lookup_buildid(unsigned long addr, |
333 | unsigned long *symbolsize, | |
334 | unsigned long *offset, char **modname, | |
335 | const unsigned char **modbuildid, char *namebuf) | |
1da177e4 | 336 | { |
74451e66 DB |
337 | const char *ret; |
338 | ||
9281acea | 339 | namebuf[KSYM_NAME_LEN - 1] = 0; |
1da177e4 LT |
340 | namebuf[0] = 0; |
341 | ||
ffc50891 FBH |
342 | if (is_ksym_addr(addr)) { |
343 | unsigned long pos; | |
1da177e4 | 344 | |
ffc50891 | 345 | pos = get_symbol_pos(addr, symbolsize, offset); |
1da177e4 | 346 | /* Grab name */ |
e3f26752 CG |
347 | kallsyms_expand_symbol(get_symbol_offset(pos), |
348 | namebuf, KSYM_NAME_LEN); | |
7a74fc49 KM |
349 | if (modname) |
350 | *modname = NULL; | |
9294523e SB |
351 | if (modbuildid) |
352 | *modbuildid = NULL; | |
8b8e6b5d ST |
353 | |
354 | ret = namebuf; | |
355 | goto found; | |
1da177e4 LT |
356 | } |
357 | ||
74451e66 DB |
358 | /* See if it's in a module or a BPF JITed image. */ |
359 | ret = module_address_lookup(addr, symbolsize, offset, | |
9294523e | 360 | modname, modbuildid, namebuf); |
74451e66 DB |
361 | if (!ret) |
362 | ret = bpf_address_lookup(addr, symbolsize, | |
363 | offset, modname, namebuf); | |
aba4b5c2 SRV |
364 | |
365 | if (!ret) | |
366 | ret = ftrace_mod_address_lookup(addr, symbolsize, | |
367 | offset, modname, namebuf); | |
8b8e6b5d ST |
368 | |
369 | found: | |
370 | cleanup_symbol_name(namebuf); | |
74451e66 | 371 | return ret; |
1da177e4 LT |
372 | } |
373 | ||
9294523e SB |
374 | /* |
375 | * Lookup an address | |
376 | * - modname is set to NULL if it's in the kernel. | |
377 | * - We guarantee that the returned name is valid until we reschedule even if. | |
378 | * It resides in a module. | |
379 | * - We also guarantee that modname will be valid until rescheduled. | |
380 | */ | |
381 | const char *kallsyms_lookup(unsigned long addr, | |
382 | unsigned long *symbolsize, | |
383 | unsigned long *offset, | |
384 | char **modname, char *namebuf) | |
385 | { | |
386 | return kallsyms_lookup_buildid(addr, symbolsize, offset, modname, | |
387 | NULL, namebuf); | |
388 | } | |
389 | ||
9d65cb4a AD |
390 | int lookup_symbol_name(unsigned long addr, char *symname) |
391 | { | |
8b8e6b5d ST |
392 | int res; |
393 | ||
9d65cb4a | 394 | symname[0] = '\0'; |
9281acea | 395 | symname[KSYM_NAME_LEN - 1] = '\0'; |
9d65cb4a AD |
396 | |
397 | if (is_ksym_addr(addr)) { | |
398 | unsigned long pos; | |
399 | ||
400 | pos = get_symbol_pos(addr, NULL, NULL); | |
401 | /* Grab name */ | |
e3f26752 CG |
402 | kallsyms_expand_symbol(get_symbol_offset(pos), |
403 | symname, KSYM_NAME_LEN); | |
8b8e6b5d | 404 | goto found; |
9d65cb4a | 405 | } |
ad6ccfad | 406 | /* See if it's in a module. */ |
8b8e6b5d ST |
407 | res = lookup_module_symbol_name(addr, symname); |
408 | if (res) | |
409 | return res; | |
410 | ||
411 | found: | |
412 | cleanup_symbol_name(symname); | |
413 | return 0; | |
9d65cb4a AD |
414 | } |
415 | ||
a5c43dae AD |
416 | int lookup_symbol_attrs(unsigned long addr, unsigned long *size, |
417 | unsigned long *offset, char *modname, char *name) | |
418 | { | |
8b8e6b5d ST |
419 | int res; |
420 | ||
a5c43dae | 421 | name[0] = '\0'; |
9281acea | 422 | name[KSYM_NAME_LEN - 1] = '\0'; |
a5c43dae AD |
423 | |
424 | if (is_ksym_addr(addr)) { | |
425 | unsigned long pos; | |
426 | ||
427 | pos = get_symbol_pos(addr, size, offset); | |
428 | /* Grab name */ | |
e3f26752 CG |
429 | kallsyms_expand_symbol(get_symbol_offset(pos), |
430 | name, KSYM_NAME_LEN); | |
a5c43dae | 431 | modname[0] = '\0'; |
8b8e6b5d | 432 | goto found; |
a5c43dae | 433 | } |
ad6ccfad | 434 | /* See if it's in a module. */ |
8b8e6b5d ST |
435 | res = lookup_module_symbol_attrs(addr, size, offset, modname, name); |
436 | if (res) | |
437 | return res; | |
438 | ||
439 | found: | |
440 | cleanup_symbol_name(name); | |
441 | return 0; | |
a5c43dae AD |
442 | } |
443 | ||
42e38083 | 444 | /* Look up a kernel symbol and return it in a text buffer. */ |
0f77a8d3 | 445 | static int __sprint_symbol(char *buffer, unsigned long address, |
9294523e | 446 | int symbol_offset, int add_offset, int add_buildid) |
1da177e4 LT |
447 | { |
448 | char *modname; | |
9294523e | 449 | const unsigned char *buildid; |
1da177e4 LT |
450 | const char *name; |
451 | unsigned long offset, size; | |
966c8c12 | 452 | int len; |
1da177e4 | 453 | |
0f77a8d3 | 454 | address += symbol_offset; |
9294523e SB |
455 | name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid, |
456 | buffer); | |
1da177e4 | 457 | if (!name) |
b86280aa | 458 | return sprintf(buffer, "0x%lx", address - symbol_offset); |
19769b76 | 459 | |
966c8c12 HD |
460 | if (name != buffer) |
461 | strcpy(buffer, name); | |
462 | len = strlen(buffer); | |
0f77a8d3 | 463 | offset -= symbol_offset; |
966c8c12 | 464 | |
4796dd20 SB |
465 | if (add_offset) |
466 | len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); | |
467 | ||
9294523e SB |
468 | if (modname) { |
469 | len += sprintf(buffer + len, " [%s", modname); | |
470 | #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) | |
471 | if (add_buildid && buildid) { | |
472 | /* build ID should match length of sprintf */ | |
473 | #if IS_ENABLED(CONFIG_MODULES) | |
474 | static_assert(sizeof(typeof_member(struct module, build_id)) == 20); | |
475 | #endif | |
476 | len += sprintf(buffer + len, " %20phN", buildid); | |
477 | } | |
478 | #endif | |
479 | len += sprintf(buffer + len, "]"); | |
480 | } | |
966c8c12 HD |
481 | |
482 | return len; | |
42e38083 | 483 | } |
0f77a8d3 NK |
484 | |
485 | /** | |
486 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer | |
487 | * @buffer: buffer to be stored | |
488 | * @address: address to lookup | |
489 | * | |
490 | * This function looks up a kernel symbol with @address and stores its name, | |
491 | * offset, size and module name to @buffer if possible. If no symbol was found, | |
492 | * just saves its @address as is. | |
493 | * | |
494 | * This function returns the number of bytes stored in @buffer. | |
495 | */ | |
496 | int sprint_symbol(char *buffer, unsigned long address) | |
497 | { | |
9294523e | 498 | return __sprint_symbol(buffer, address, 0, 1, 0); |
0f77a8d3 | 499 | } |
ad6ccfad | 500 | EXPORT_SYMBOL_GPL(sprint_symbol); |
42e38083 | 501 | |
9294523e SB |
502 | /** |
503 | * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer | |
504 | * @buffer: buffer to be stored | |
505 | * @address: address to lookup | |
506 | * | |
507 | * This function looks up a kernel symbol with @address and stores its name, | |
508 | * offset, size, module name and module build ID to @buffer if possible. If no | |
509 | * symbol was found, just saves its @address as is. | |
510 | * | |
511 | * This function returns the number of bytes stored in @buffer. | |
512 | */ | |
513 | int sprint_symbol_build_id(char *buffer, unsigned long address) | |
514 | { | |
515 | return __sprint_symbol(buffer, address, 0, 1, 1); | |
516 | } | |
517 | EXPORT_SYMBOL_GPL(sprint_symbol_build_id); | |
518 | ||
4796dd20 SB |
519 | /** |
520 | * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer | |
521 | * @buffer: buffer to be stored | |
522 | * @address: address to lookup | |
523 | * | |
524 | * This function looks up a kernel symbol with @address and stores its name | |
525 | * and module name to @buffer if possible. If no symbol was found, just saves | |
526 | * its @address as is. | |
527 | * | |
528 | * This function returns the number of bytes stored in @buffer. | |
529 | */ | |
530 | int sprint_symbol_no_offset(char *buffer, unsigned long address) | |
531 | { | |
9294523e | 532 | return __sprint_symbol(buffer, address, 0, 0, 0); |
4796dd20 SB |
533 | } |
534 | EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); | |
535 | ||
0f77a8d3 NK |
536 | /** |
537 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer | |
538 | * @buffer: buffer to be stored | |
539 | * @address: address to lookup | |
540 | * | |
541 | * This function is for stack backtrace and does the same thing as | |
542 | * sprint_symbol() but with modified/decreased @address. If there is a | |
543 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
544 | * the call so that the stack-saved return address could point outside of the | |
545 | * caller. This function ensures that kallsyms will find the original caller | |
546 | * by decreasing @address. | |
547 | * | |
548 | * This function returns the number of bytes stored in @buffer. | |
549 | */ | |
550 | int sprint_backtrace(char *buffer, unsigned long address) | |
551 | { | |
9294523e SB |
552 | return __sprint_symbol(buffer, address, -1, 1, 0); |
553 | } | |
554 | ||
555 | /** | |
556 | * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer | |
557 | * @buffer: buffer to be stored | |
558 | * @address: address to lookup | |
559 | * | |
560 | * This function is for stack backtrace and does the same thing as | |
561 | * sprint_symbol() but with modified/decreased @address. If there is a | |
562 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
563 | * the call so that the stack-saved return address could point outside of the | |
564 | * caller. This function ensures that kallsyms will find the original caller | |
565 | * by decreasing @address. This function also appends the module build ID to | |
566 | * the @buffer if @address is within a kernel module. | |
567 | * | |
568 | * This function returns the number of bytes stored in @buffer. | |
569 | */ | |
570 | int sprint_backtrace_build_id(char *buffer, unsigned long address) | |
571 | { | |
572 | return __sprint_symbol(buffer, address, -1, 1, 1); | |
0f77a8d3 NK |
573 | } |
574 | ||
1da177e4 | 575 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ |
ad6ccfad | 576 | struct kallsym_iter { |
1da177e4 | 577 | loff_t pos; |
d83212d5 | 578 | loff_t pos_arch_end; |
74451e66 | 579 | loff_t pos_mod_end; |
6171a031 | 580 | loff_t pos_ftrace_mod_end; |
d002b8bc | 581 | loff_t pos_bpf_end; |
1da177e4 | 582 | unsigned long value; |
ad6ccfad | 583 | unsigned int nameoff; /* If iterating in core kernel symbols. */ |
1da177e4 | 584 | char type; |
9281acea TH |
585 | char name[KSYM_NAME_LEN]; |
586 | char module_name[MODULE_NAME_LEN]; | |
ea07890a | 587 | int exported; |
c0f3ea15 | 588 | int show_value; |
1da177e4 LT |
589 | }; |
590 | ||
d83212d5 AS |
591 | int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value, |
592 | char *type, char *name) | |
593 | { | |
594 | return -EINVAL; | |
595 | } | |
596 | ||
597 | static int get_ksymbol_arch(struct kallsym_iter *iter) | |
598 | { | |
599 | int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms, | |
600 | &iter->value, &iter->type, | |
601 | iter->name); | |
602 | ||
603 | if (ret < 0) { | |
604 | iter->pos_arch_end = iter->pos; | |
605 | return 0; | |
606 | } | |
607 | ||
608 | return 1; | |
609 | } | |
610 | ||
1da177e4 LT |
611 | static int get_ksymbol_mod(struct kallsym_iter *iter) |
612 | { | |
d83212d5 | 613 | int ret = module_get_kallsym(iter->pos - iter->pos_arch_end, |
74451e66 DB |
614 | &iter->value, &iter->type, |
615 | iter->name, iter->module_name, | |
616 | &iter->exported); | |
617 | if (ret < 0) { | |
618 | iter->pos_mod_end = iter->pos; | |
1da177e4 | 619 | return 0; |
74451e66 DB |
620 | } |
621 | ||
1da177e4 LT |
622 | return 1; |
623 | } | |
624 | ||
fc0ea795 AH |
625 | /* |
626 | * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace | |
627 | * purposes. In that case "__builtin__ftrace" is used as a module name, even | |
628 | * though "__builtin__ftrace" is not a module. | |
629 | */ | |
6171a031 SRV |
630 | static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter) |
631 | { | |
632 | int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end, | |
633 | &iter->value, &iter->type, | |
634 | iter->name, iter->module_name, | |
635 | &iter->exported); | |
636 | if (ret < 0) { | |
637 | iter->pos_ftrace_mod_end = iter->pos; | |
638 | return 0; | |
639 | } | |
640 | ||
641 | return 1; | |
642 | } | |
643 | ||
74451e66 DB |
644 | static int get_ksymbol_bpf(struct kallsym_iter *iter) |
645 | { | |
d002b8bc AH |
646 | int ret; |
647 | ||
6934058d | 648 | strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN); |
74451e66 | 649 | iter->exported = 0; |
d002b8bc AH |
650 | ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end, |
651 | &iter->value, &iter->type, | |
652 | iter->name); | |
653 | if (ret < 0) { | |
654 | iter->pos_bpf_end = iter->pos; | |
655 | return 0; | |
656 | } | |
657 | ||
658 | return 1; | |
659 | } | |
660 | ||
661 | /* | |
662 | * This uses "__builtin__kprobes" as a module name for symbols for pages | |
663 | * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a | |
664 | * module. | |
665 | */ | |
666 | static int get_ksymbol_kprobe(struct kallsym_iter *iter) | |
667 | { | |
668 | strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN); | |
669 | iter->exported = 0; | |
670 | return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end, | |
671 | &iter->value, &iter->type, | |
672 | iter->name) < 0 ? 0 : 1; | |
74451e66 DB |
673 | } |
674 | ||
1da177e4 LT |
675 | /* Returns space to next name. */ |
676 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
677 | { | |
678 | unsigned off = iter->nameoff; | |
679 | ||
ea07890a | 680 | iter->module_name[0] = '\0'; |
2213e9a6 | 681 | iter->value = kallsyms_sym_address(iter->pos); |
1da177e4 LT |
682 | |
683 | iter->type = kallsyms_get_symbol_type(off); | |
684 | ||
e3f26752 | 685 | off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name)); |
1da177e4 LT |
686 | |
687 | return off - iter->nameoff; | |
688 | } | |
689 | ||
690 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
691 | { | |
692 | iter->name[0] = '\0'; | |
693 | iter->nameoff = get_symbol_offset(new_pos); | |
694 | iter->pos = new_pos; | |
6171a031 | 695 | if (new_pos == 0) { |
d83212d5 | 696 | iter->pos_arch_end = 0; |
74451e66 | 697 | iter->pos_mod_end = 0; |
6171a031 | 698 | iter->pos_ftrace_mod_end = 0; |
d002b8bc | 699 | iter->pos_bpf_end = 0; |
6171a031 | 700 | } |
74451e66 DB |
701 | } |
702 | ||
b9667942 AH |
703 | /* |
704 | * The end position (last + 1) of each additional kallsyms section is recorded | |
705 | * in iter->pos_..._end as each section is added, and so can be used to | |
706 | * determine which get_ksymbol_...() function to call next. | |
707 | */ | |
74451e66 DB |
708 | static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) |
709 | { | |
710 | iter->pos = pos; | |
711 | ||
d83212d5 AS |
712 | if ((!iter->pos_arch_end || iter->pos_arch_end > pos) && |
713 | get_ksymbol_arch(iter)) | |
714 | return 1; | |
715 | ||
b9667942 AH |
716 | if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && |
717 | get_ksymbol_mod(iter)) | |
6171a031 | 718 | return 1; |
6171a031 | 719 | |
b9667942 AH |
720 | if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) && |
721 | get_ksymbol_ftrace_mod(iter)) | |
722 | return 1; | |
74451e66 | 723 | |
d002b8bc AH |
724 | if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) && |
725 | get_ksymbol_bpf(iter)) | |
726 | return 1; | |
727 | ||
728 | return get_ksymbol_kprobe(iter); | |
1da177e4 LT |
729 | } |
730 | ||
731 | /* Returns false if pos at or past end of file. */ | |
732 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
733 | { | |
734 | /* Module symbols can be accessed randomly. */ | |
74451e66 DB |
735 | if (pos >= kallsyms_num_syms) |
736 | return update_iter_mod(iter, pos); | |
ad6ccfad | 737 | |
1da177e4 LT |
738 | /* If we're not on the desired position, reset to new position. */ |
739 | if (pos != iter->pos) | |
740 | reset_iter(iter, pos); | |
741 | ||
742 | iter->nameoff += get_ksymbol_core(iter); | |
743 | iter->pos++; | |
744 | ||
745 | return 1; | |
746 | } | |
747 | ||
748 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
749 | { | |
750 | (*pos)++; | |
751 | ||
752 | if (!update_iter(m->private, *pos)) | |
753 | return NULL; | |
754 | return p; | |
755 | } | |
756 | ||
757 | static void *s_start(struct seq_file *m, loff_t *pos) | |
758 | { | |
759 | if (!update_iter(m->private, *pos)) | |
760 | return NULL; | |
761 | return m->private; | |
762 | } | |
763 | ||
764 | static void s_stop(struct seq_file *m, void *p) | |
765 | { | |
766 | } | |
767 | ||
768 | static int s_show(struct seq_file *m, void *p) | |
769 | { | |
668533dc | 770 | void *value; |
1da177e4 LT |
771 | struct kallsym_iter *iter = m->private; |
772 | ||
ad6ccfad | 773 | /* Some debugging symbols have no name. Ignore them. */ |
1da177e4 LT |
774 | if (!iter->name[0]) |
775 | return 0; | |
776 | ||
668533dc | 777 | value = iter->show_value ? (void *)iter->value : NULL; |
c0f3ea15 | 778 | |
ea07890a AD |
779 | if (iter->module_name[0]) { |
780 | char type; | |
781 | ||
ad6ccfad MK |
782 | /* |
783 | * Label it "global" if it is exported, | |
784 | * "local" if not exported. | |
785 | */ | |
ea07890a AD |
786 | type = iter->exported ? toupper(iter->type) : |
787 | tolower(iter->type); | |
668533dc | 788 | seq_printf(m, "%px %c %s\t[%s]\n", value, |
9f36e2c4 | 789 | type, iter->name, iter->module_name); |
ea07890a | 790 | } else |
668533dc | 791 | seq_printf(m, "%px %c %s\n", value, |
9f36e2c4 | 792 | iter->type, iter->name); |
1da177e4 LT |
793 | return 0; |
794 | } | |
795 | ||
15ad7cdc | 796 | static const struct seq_operations kallsyms_op = { |
1da177e4 LT |
797 | .start = s_start, |
798 | .next = s_next, | |
799 | .stop = s_stop, | |
800 | .show = s_show | |
801 | }; | |
802 | ||
647cafa2 AM |
803 | #ifdef CONFIG_BPF_SYSCALL |
804 | ||
805 | struct bpf_iter__ksym { | |
806 | __bpf_md_ptr(struct bpf_iter_meta *, meta); | |
807 | __bpf_md_ptr(struct kallsym_iter *, ksym); | |
808 | }; | |
809 | ||
810 | static int ksym_prog_seq_show(struct seq_file *m, bool in_stop) | |
811 | { | |
812 | struct bpf_iter__ksym ctx; | |
813 | struct bpf_iter_meta meta; | |
814 | struct bpf_prog *prog; | |
815 | ||
816 | meta.seq = m; | |
817 | prog = bpf_iter_get_info(&meta, in_stop); | |
818 | if (!prog) | |
819 | return 0; | |
820 | ||
821 | ctx.meta = &meta; | |
822 | ctx.ksym = m ? m->private : NULL; | |
823 | return bpf_iter_run_prog(prog, &ctx); | |
824 | } | |
825 | ||
826 | static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p) | |
827 | { | |
828 | return ksym_prog_seq_show(m, false); | |
829 | } | |
830 | ||
831 | static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p) | |
832 | { | |
833 | if (!p) | |
834 | (void) ksym_prog_seq_show(m, true); | |
835 | else | |
836 | s_stop(m, p); | |
837 | } | |
838 | ||
839 | static const struct seq_operations bpf_iter_ksym_ops = { | |
840 | .start = s_start, | |
841 | .next = s_next, | |
842 | .stop = bpf_iter_ksym_seq_stop, | |
843 | .show = bpf_iter_ksym_seq_show, | |
844 | }; | |
845 | ||
846 | static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux) | |
847 | { | |
848 | struct kallsym_iter *iter = priv_data; | |
849 | ||
850 | reset_iter(iter, 0); | |
851 | ||
852 | /* cache here as in kallsyms_open() case; use current process | |
853 | * credentials to tell BPF iterators if values should be shown. | |
854 | */ | |
855 | iter->show_value = kallsyms_show_value(current_cred()); | |
856 | ||
857 | return 0; | |
858 | } | |
859 | ||
860 | DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym) | |
861 | ||
862 | static const struct bpf_iter_seq_info ksym_iter_seq_info = { | |
863 | .seq_ops = &bpf_iter_ksym_ops, | |
864 | .init_seq_private = bpf_iter_ksym_init, | |
865 | .fini_seq_private = NULL, | |
866 | .seq_priv_size = sizeof(struct kallsym_iter), | |
867 | }; | |
868 | ||
869 | static struct bpf_iter_reg ksym_iter_reg_info = { | |
870 | .target = "ksym", | |
871 | .feature = BPF_ITER_RESCHED, | |
872 | .ctx_arg_info_size = 1, | |
873 | .ctx_arg_info = { | |
874 | { offsetof(struct bpf_iter__ksym, ksym), | |
875 | PTR_TO_BTF_ID_OR_NULL }, | |
876 | }, | |
877 | .seq_info = &ksym_iter_seq_info, | |
878 | }; | |
879 | ||
880 | BTF_ID_LIST(btf_ksym_iter_id) | |
881 | BTF_ID(struct, kallsym_iter) | |
882 | ||
883 | static int __init bpf_ksym_iter_register(void) | |
884 | { | |
885 | ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id; | |
886 | return bpf_iter_reg_target(&ksym_iter_reg_info); | |
887 | } | |
888 | ||
889 | late_initcall(bpf_ksym_iter_register); | |
890 | ||
891 | #endif /* CONFIG_BPF_SYSCALL */ | |
892 | ||
c0f3ea15 LT |
893 | static inline int kallsyms_for_perf(void) |
894 | { | |
895 | #ifdef CONFIG_PERF_EVENTS | |
896 | extern int sysctl_perf_event_paranoid; | |
897 | if (sysctl_perf_event_paranoid <= 1) | |
898 | return 1; | |
899 | #endif | |
900 | return 0; | |
901 | } | |
902 | ||
903 | /* | |
904 | * We show kallsyms information even to normal users if we've enabled | |
905 | * kernel profiling and are explicitly not paranoid (so kptr_restrict | |
906 | * is clear, and sysctl_perf_event_paranoid isn't set). | |
907 | * | |
908 | * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to | |
909 | * block even that). | |
910 | */ | |
16025184 | 911 | bool kallsyms_show_value(const struct cred *cred) |
c0f3ea15 LT |
912 | { |
913 | switch (kptr_restrict) { | |
914 | case 0: | |
915 | if (kallsyms_for_perf()) | |
16025184 | 916 | return true; |
df561f66 | 917 | fallthrough; |
c0f3ea15 | 918 | case 1: |
16025184 KC |
919 | if (security_capable(cred, &init_user_ns, CAP_SYSLOG, |
920 | CAP_OPT_NOAUDIT) == 0) | |
921 | return true; | |
df561f66 | 922 | fallthrough; |
c0f3ea15 | 923 | default: |
16025184 | 924 | return false; |
c0f3ea15 LT |
925 | } |
926 | } | |
927 | ||
1da177e4 LT |
928 | static int kallsyms_open(struct inode *inode, struct file *file) |
929 | { | |
ad6ccfad MK |
930 | /* |
931 | * We keep iterator in m->private, since normal case is to | |
1da177e4 | 932 | * s_start from where we left off, so we avoid doing |
ad6ccfad MK |
933 | * using get_symbol_offset for every symbol. |
934 | */ | |
1da177e4 | 935 | struct kallsym_iter *iter; |
0049f26a | 936 | iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter)); |
1da177e4 LT |
937 | if (!iter) |
938 | return -ENOMEM; | |
939 | reset_iter(iter, 0); | |
940 | ||
16025184 KC |
941 | /* |
942 | * Instead of checking this on every s_show() call, cache | |
943 | * the result here at open time. | |
944 | */ | |
945 | iter->show_value = kallsyms_show_value(file->f_cred); | |
0049f26a | 946 | return 0; |
1da177e4 LT |
947 | } |
948 | ||
67fc4e0c JW |
949 | #ifdef CONFIG_KGDB_KDB |
950 | const char *kdb_walk_kallsyms(loff_t *pos) | |
951 | { | |
952 | static struct kallsym_iter kdb_walk_kallsyms_iter; | |
953 | if (*pos == 0) { | |
954 | memset(&kdb_walk_kallsyms_iter, 0, | |
955 | sizeof(kdb_walk_kallsyms_iter)); | |
956 | reset_iter(&kdb_walk_kallsyms_iter, 0); | |
957 | } | |
958 | while (1) { | |
959 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) | |
960 | return NULL; | |
961 | ++*pos; | |
962 | /* Some debugging symbols have no name. Ignore them. */ | |
963 | if (kdb_walk_kallsyms_iter.name[0]) | |
964 | return kdb_walk_kallsyms_iter.name; | |
965 | } | |
966 | } | |
967 | #endif /* CONFIG_KGDB_KDB */ | |
968 | ||
97a32539 AD |
969 | static const struct proc_ops kallsyms_proc_ops = { |
970 | .proc_open = kallsyms_open, | |
971 | .proc_read = seq_read, | |
972 | .proc_lseek = seq_lseek, | |
973 | .proc_release = seq_release_private, | |
1da177e4 LT |
974 | }; |
975 | ||
976 | static int __init kallsyms_init(void) | |
977 | { | |
97a32539 | 978 | proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops); |
1da177e4 LT |
979 | return 0; |
980 | } | |
ad6ccfad | 981 | device_initcall(kallsyms_init); |