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1 | /* | |
2 | * kallsyms.c: in-kernel printing of symbolic oopses and stack traces. | |
3 | * | |
4 | * Rewritten and vastly simplified by Rusty Russell for in-kernel | |
5 | * module loader: | |
6 | * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation | |
7 | * | |
8 | * ChangeLog: | |
9 | * | |
10 | * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com> | |
11 | * Changed the compression method from stem compression to "table lookup" | |
12 | * compression (see scripts/kallsyms.c for a more complete description) | |
13 | */ | |
14 | #include <linux/kallsyms.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/seq_file.h> | |
18 | #include <linux/fs.h> | |
19 | #include <linux/kdb.h> | |
20 | #include <linux/err.h> | |
21 | #include <linux/proc_fs.h> | |
22 | #include <linux/sched.h> /* for cond_resched */ | |
23 | #include <linux/mm.h> | |
24 | #include <linux/ctype.h> | |
25 | #include <linux/slab.h> | |
26 | #include <linux/filter.h> | |
27 | #include <linux/ftrace.h> | |
28 | #include <linux/compiler.h> | |
29 | ||
30 | #include <asm/sections.h> | |
31 | ||
32 | /* | |
33 | * These will be re-linked against their real values | |
34 | * during the second link stage. | |
35 | */ | |
36 | extern const unsigned long kallsyms_addresses[] __weak; | |
37 | extern const int kallsyms_offsets[] __weak; | |
38 | extern const u8 kallsyms_names[] __weak; | |
39 | ||
40 | /* | |
41 | * Tell the compiler that the count isn't in the small data section if the arch | |
42 | * has one (eg: FRV). | |
43 | */ | |
44 | extern const unsigned long kallsyms_num_syms | |
45 | __attribute__((weak, section(".rodata"))); | |
46 | ||
47 | extern const unsigned long kallsyms_relative_base | |
48 | __attribute__((weak, section(".rodata"))); | |
49 | ||
50 | extern const u8 kallsyms_token_table[] __weak; | |
51 | extern const u16 kallsyms_token_index[] __weak; | |
52 | ||
53 | extern const unsigned long kallsyms_markers[] __weak; | |
54 | ||
55 | static inline int is_kernel_inittext(unsigned long addr) | |
56 | { | |
57 | if (addr >= (unsigned long)_sinittext | |
58 | && addr <= (unsigned long)_einittext) | |
59 | return 1; | |
60 | return 0; | |
61 | } | |
62 | ||
63 | static inline int is_kernel_text(unsigned long addr) | |
64 | { | |
65 | if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) || | |
66 | arch_is_kernel_text(addr)) | |
67 | return 1; | |
68 | return in_gate_area_no_mm(addr); | |
69 | } | |
70 | ||
71 | static inline int is_kernel(unsigned long addr) | |
72 | { | |
73 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) | |
74 | return 1; | |
75 | return in_gate_area_no_mm(addr); | |
76 | } | |
77 | ||
78 | static int is_ksym_addr(unsigned long addr) | |
79 | { | |
80 | if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) | |
81 | return is_kernel(addr); | |
82 | ||
83 | return is_kernel_text(addr) || is_kernel_inittext(addr); | |
84 | } | |
85 | ||
86 | /* | |
87 | * Expand a compressed symbol data into the resulting uncompressed string, | |
88 | * if uncompressed string is too long (>= maxlen), it will be truncated, | |
89 | * given the offset to where the symbol is in the compressed stream. | |
90 | */ | |
91 | static unsigned int kallsyms_expand_symbol(unsigned int off, | |
92 | char *result, size_t maxlen) | |
93 | { | |
94 | int len, skipped_first = 0; | |
95 | const u8 *tptr, *data; | |
96 | ||
97 | /* Get the compressed symbol length from the first symbol byte. */ | |
98 | data = &kallsyms_names[off]; | |
99 | len = *data; | |
100 | data++; | |
101 | ||
102 | /* | |
103 | * Update the offset to return the offset for the next symbol on | |
104 | * the compressed stream. | |
105 | */ | |
106 | off += len + 1; | |
107 | ||
108 | /* | |
109 | * For every byte on the compressed symbol data, copy the table | |
110 | * entry for that byte. | |
111 | */ | |
112 | while (len) { | |
113 | tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; | |
114 | data++; | |
115 | len--; | |
116 | ||
117 | while (*tptr) { | |
118 | if (skipped_first) { | |
119 | if (maxlen <= 1) | |
120 | goto tail; | |
121 | *result = *tptr; | |
122 | result++; | |
123 | maxlen--; | |
124 | } else | |
125 | skipped_first = 1; | |
126 | tptr++; | |
127 | } | |
128 | } | |
129 | ||
130 | tail: | |
131 | if (maxlen) | |
132 | *result = '\0'; | |
133 | ||
134 | /* Return to offset to the next symbol. */ | |
135 | return off; | |
136 | } | |
137 | ||
138 | /* | |
139 | * Get symbol type information. This is encoded as a single char at the | |
140 | * beginning of the symbol name. | |
141 | */ | |
142 | static char kallsyms_get_symbol_type(unsigned int off) | |
143 | { | |
144 | /* | |
145 | * Get just the first code, look it up in the token table, | |
146 | * and return the first char from this token. | |
147 | */ | |
148 | return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; | |
149 | } | |
150 | ||
151 | ||
152 | /* | |
153 | * Find the offset on the compressed stream given and index in the | |
154 | * kallsyms array. | |
155 | */ | |
156 | static unsigned int get_symbol_offset(unsigned long pos) | |
157 | { | |
158 | const u8 *name; | |
159 | int i; | |
160 | ||
161 | /* | |
162 | * Use the closest marker we have. We have markers every 256 positions, | |
163 | * so that should be close enough. | |
164 | */ | |
165 | name = &kallsyms_names[kallsyms_markers[pos >> 8]]; | |
166 | ||
167 | /* | |
168 | * Sequentially scan all the symbols up to the point we're searching | |
169 | * for. Every symbol is stored in a [<len>][<len> bytes of data] format, | |
170 | * so we just need to add the len to the current pointer for every | |
171 | * symbol we wish to skip. | |
172 | */ | |
173 | for (i = 0; i < (pos & 0xFF); i++) | |
174 | name = name + (*name) + 1; | |
175 | ||
176 | return name - kallsyms_names; | |
177 | } | |
178 | ||
179 | static unsigned long kallsyms_sym_address(int idx) | |
180 | { | |
181 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) | |
182 | return kallsyms_addresses[idx]; | |
183 | ||
184 | /* values are unsigned offsets if --absolute-percpu is not in effect */ | |
185 | if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU)) | |
186 | return kallsyms_relative_base + (u32)kallsyms_offsets[idx]; | |
187 | ||
188 | /* ...otherwise, positive offsets are absolute values */ | |
189 | if (kallsyms_offsets[idx] >= 0) | |
190 | return kallsyms_offsets[idx]; | |
191 | ||
192 | /* ...and negative offsets are relative to kallsyms_relative_base - 1 */ | |
193 | return kallsyms_relative_base - 1 - kallsyms_offsets[idx]; | |
194 | } | |
195 | ||
196 | /* Lookup the address for this symbol. Returns 0 if not found. */ | |
197 | unsigned long kallsyms_lookup_name(const char *name) | |
198 | { | |
199 | char namebuf[KSYM_NAME_LEN]; | |
200 | unsigned long i; | |
201 | unsigned int off; | |
202 | ||
203 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
204 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); | |
205 | ||
206 | if (strcmp(namebuf, name) == 0) | |
207 | return kallsyms_sym_address(i); | |
208 | } | |
209 | return module_kallsyms_lookup_name(name); | |
210 | } | |
211 | EXPORT_SYMBOL_GPL(kallsyms_lookup_name); | |
212 | ||
213 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, | |
214 | unsigned long), | |
215 | void *data) | |
216 | { | |
217 | char namebuf[KSYM_NAME_LEN]; | |
218 | unsigned long i; | |
219 | unsigned int off; | |
220 | int ret; | |
221 | ||
222 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
223 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); | |
224 | ret = fn(data, namebuf, NULL, kallsyms_sym_address(i)); | |
225 | if (ret != 0) | |
226 | return ret; | |
227 | } | |
228 | return module_kallsyms_on_each_symbol(fn, data); | |
229 | } | |
230 | EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol); | |
231 | ||
232 | static unsigned long get_symbol_pos(unsigned long addr, | |
233 | unsigned long *symbolsize, | |
234 | unsigned long *offset) | |
235 | { | |
236 | unsigned long symbol_start = 0, symbol_end = 0; | |
237 | unsigned long i, low, high, mid; | |
238 | ||
239 | /* This kernel should never had been booted. */ | |
240 | if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) | |
241 | BUG_ON(!kallsyms_addresses); | |
242 | else | |
243 | BUG_ON(!kallsyms_offsets); | |
244 | ||
245 | /* Do a binary search on the sorted kallsyms_addresses array. */ | |
246 | low = 0; | |
247 | high = kallsyms_num_syms; | |
248 | ||
249 | while (high - low > 1) { | |
250 | mid = low + (high - low) / 2; | |
251 | if (kallsyms_sym_address(mid) <= addr) | |
252 | low = mid; | |
253 | else | |
254 | high = mid; | |
255 | } | |
256 | ||
257 | /* | |
258 | * Search for the first aliased symbol. Aliased | |
259 | * symbols are symbols with the same address. | |
260 | */ | |
261 | while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low)) | |
262 | --low; | |
263 | ||
264 | symbol_start = kallsyms_sym_address(low); | |
265 | ||
266 | /* Search for next non-aliased symbol. */ | |
267 | for (i = low + 1; i < kallsyms_num_syms; i++) { | |
268 | if (kallsyms_sym_address(i) > symbol_start) { | |
269 | symbol_end = kallsyms_sym_address(i); | |
270 | break; | |
271 | } | |
272 | } | |
273 | ||
274 | /* If we found no next symbol, we use the end of the section. */ | |
275 | if (!symbol_end) { | |
276 | if (is_kernel_inittext(addr)) | |
277 | symbol_end = (unsigned long)_einittext; | |
278 | else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) | |
279 | symbol_end = (unsigned long)_end; | |
280 | else | |
281 | symbol_end = (unsigned long)_etext; | |
282 | } | |
283 | ||
284 | if (symbolsize) | |
285 | *symbolsize = symbol_end - symbol_start; | |
286 | if (offset) | |
287 | *offset = addr - symbol_start; | |
288 | ||
289 | return low; | |
290 | } | |
291 | ||
292 | /* | |
293 | * Lookup an address but don't bother to find any names. | |
294 | */ | |
295 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, | |
296 | unsigned long *offset) | |
297 | { | |
298 | char namebuf[KSYM_NAME_LEN]; | |
299 | ||
300 | if (is_ksym_addr(addr)) { | |
301 | get_symbol_pos(addr, symbolsize, offset); | |
302 | return 1; | |
303 | } | |
304 | return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) || | |
305 | !!__bpf_address_lookup(addr, symbolsize, offset, namebuf); | |
306 | } | |
307 | ||
308 | /* | |
309 | * Lookup an address | |
310 | * - modname is set to NULL if it's in the kernel. | |
311 | * - We guarantee that the returned name is valid until we reschedule even if. | |
312 | * It resides in a module. | |
313 | * - We also guarantee that modname will be valid until rescheduled. | |
314 | */ | |
315 | const char *kallsyms_lookup(unsigned long addr, | |
316 | unsigned long *symbolsize, | |
317 | unsigned long *offset, | |
318 | char **modname, char *namebuf) | |
319 | { | |
320 | const char *ret; | |
321 | ||
322 | namebuf[KSYM_NAME_LEN - 1] = 0; | |
323 | namebuf[0] = 0; | |
324 | ||
325 | if (is_ksym_addr(addr)) { | |
326 | unsigned long pos; | |
327 | ||
328 | pos = get_symbol_pos(addr, symbolsize, offset); | |
329 | /* Grab name */ | |
330 | kallsyms_expand_symbol(get_symbol_offset(pos), | |
331 | namebuf, KSYM_NAME_LEN); | |
332 | if (modname) | |
333 | *modname = NULL; | |
334 | return namebuf; | |
335 | } | |
336 | ||
337 | /* See if it's in a module or a BPF JITed image. */ | |
338 | ret = module_address_lookup(addr, symbolsize, offset, | |
339 | modname, namebuf); | |
340 | if (!ret) | |
341 | ret = bpf_address_lookup(addr, symbolsize, | |
342 | offset, modname, namebuf); | |
343 | ||
344 | if (!ret) | |
345 | ret = ftrace_mod_address_lookup(addr, symbolsize, | |
346 | offset, modname, namebuf); | |
347 | return ret; | |
348 | } | |
349 | ||
350 | int lookup_symbol_name(unsigned long addr, char *symname) | |
351 | { | |
352 | symname[0] = '\0'; | |
353 | symname[KSYM_NAME_LEN - 1] = '\0'; | |
354 | ||
355 | if (is_ksym_addr(addr)) { | |
356 | unsigned long pos; | |
357 | ||
358 | pos = get_symbol_pos(addr, NULL, NULL); | |
359 | /* Grab name */ | |
360 | kallsyms_expand_symbol(get_symbol_offset(pos), | |
361 | symname, KSYM_NAME_LEN); | |
362 | return 0; | |
363 | } | |
364 | /* See if it's in a module. */ | |
365 | return lookup_module_symbol_name(addr, symname); | |
366 | } | |
367 | ||
368 | int lookup_symbol_attrs(unsigned long addr, unsigned long *size, | |
369 | unsigned long *offset, char *modname, char *name) | |
370 | { | |
371 | name[0] = '\0'; | |
372 | name[KSYM_NAME_LEN - 1] = '\0'; | |
373 | ||
374 | if (is_ksym_addr(addr)) { | |
375 | unsigned long pos; | |
376 | ||
377 | pos = get_symbol_pos(addr, size, offset); | |
378 | /* Grab name */ | |
379 | kallsyms_expand_symbol(get_symbol_offset(pos), | |
380 | name, KSYM_NAME_LEN); | |
381 | modname[0] = '\0'; | |
382 | return 0; | |
383 | } | |
384 | /* See if it's in a module. */ | |
385 | return lookup_module_symbol_attrs(addr, size, offset, modname, name); | |
386 | } | |
387 | ||
388 | /* Look up a kernel symbol and return it in a text buffer. */ | |
389 | static int __sprint_symbol(char *buffer, unsigned long address, | |
390 | int symbol_offset, int add_offset) | |
391 | { | |
392 | char *modname; | |
393 | const char *name; | |
394 | unsigned long offset, size; | |
395 | int len; | |
396 | ||
397 | address += symbol_offset; | |
398 | name = kallsyms_lookup(address, &size, &offset, &modname, buffer); | |
399 | if (!name) | |
400 | return sprintf(buffer, "0x%lx", address - symbol_offset); | |
401 | ||
402 | if (name != buffer) | |
403 | strcpy(buffer, name); | |
404 | len = strlen(buffer); | |
405 | offset -= symbol_offset; | |
406 | ||
407 | if (add_offset) | |
408 | len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); | |
409 | ||
410 | if (modname) | |
411 | len += sprintf(buffer + len, " [%s]", modname); | |
412 | ||
413 | return len; | |
414 | } | |
415 | ||
416 | /** | |
417 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer | |
418 | * @buffer: buffer to be stored | |
419 | * @address: address to lookup | |
420 | * | |
421 | * This function looks up a kernel symbol with @address and stores its name, | |
422 | * offset, size and module name to @buffer if possible. If no symbol was found, | |
423 | * just saves its @address as is. | |
424 | * | |
425 | * This function returns the number of bytes stored in @buffer. | |
426 | */ | |
427 | int sprint_symbol(char *buffer, unsigned long address) | |
428 | { | |
429 | return __sprint_symbol(buffer, address, 0, 1); | |
430 | } | |
431 | EXPORT_SYMBOL_GPL(sprint_symbol); | |
432 | ||
433 | /** | |
434 | * sprint_symbol_no_offset - 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 | * and module name to @buffer if possible. If no symbol was found, just saves | |
440 | * its @address as is. | |
441 | * | |
442 | * This function returns the number of bytes stored in @buffer. | |
443 | */ | |
444 | int sprint_symbol_no_offset(char *buffer, unsigned long address) | |
445 | { | |
446 | return __sprint_symbol(buffer, address, 0, 0); | |
447 | } | |
448 | EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); | |
449 | ||
450 | /** | |
451 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer | |
452 | * @buffer: buffer to be stored | |
453 | * @address: address to lookup | |
454 | * | |
455 | * This function is for stack backtrace and does the same thing as | |
456 | * sprint_symbol() but with modified/decreased @address. If there is a | |
457 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
458 | * the call so that the stack-saved return address could point outside of the | |
459 | * caller. This function ensures that kallsyms will find the original caller | |
460 | * by decreasing @address. | |
461 | * | |
462 | * This function returns the number of bytes stored in @buffer. | |
463 | */ | |
464 | int sprint_backtrace(char *buffer, unsigned long address) | |
465 | { | |
466 | return __sprint_symbol(buffer, address, -1, 1); | |
467 | } | |
468 | ||
469 | /* Look up a kernel symbol and print it to the kernel messages. */ | |
470 | void __print_symbol(const char *fmt, unsigned long address) | |
471 | { | |
472 | char buffer[KSYM_SYMBOL_LEN]; | |
473 | ||
474 | sprint_symbol(buffer, address); | |
475 | ||
476 | printk(fmt, buffer); | |
477 | } | |
478 | EXPORT_SYMBOL(__print_symbol); | |
479 | ||
480 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ | |
481 | struct kallsym_iter { | |
482 | loff_t pos; | |
483 | loff_t pos_mod_end; | |
484 | loff_t pos_ftrace_mod_end; | |
485 | unsigned long value; | |
486 | unsigned int nameoff; /* If iterating in core kernel symbols. */ | |
487 | char type; | |
488 | char name[KSYM_NAME_LEN]; | |
489 | char module_name[MODULE_NAME_LEN]; | |
490 | int exported; | |
491 | int show_value; | |
492 | }; | |
493 | ||
494 | static int get_ksymbol_mod(struct kallsym_iter *iter) | |
495 | { | |
496 | int ret = module_get_kallsym(iter->pos - kallsyms_num_syms, | |
497 | &iter->value, &iter->type, | |
498 | iter->name, iter->module_name, | |
499 | &iter->exported); | |
500 | if (ret < 0) { | |
501 | iter->pos_mod_end = iter->pos; | |
502 | return 0; | |
503 | } | |
504 | ||
505 | return 1; | |
506 | } | |
507 | ||
508 | static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter) | |
509 | { | |
510 | int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end, | |
511 | &iter->value, &iter->type, | |
512 | iter->name, iter->module_name, | |
513 | &iter->exported); | |
514 | if (ret < 0) { | |
515 | iter->pos_ftrace_mod_end = iter->pos; | |
516 | return 0; | |
517 | } | |
518 | ||
519 | return 1; | |
520 | } | |
521 | ||
522 | static int get_ksymbol_bpf(struct kallsym_iter *iter) | |
523 | { | |
524 | iter->module_name[0] = '\0'; | |
525 | iter->exported = 0; | |
526 | return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end, | |
527 | &iter->value, &iter->type, | |
528 | iter->name) < 0 ? 0 : 1; | |
529 | } | |
530 | ||
531 | /* Returns space to next name. */ | |
532 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
533 | { | |
534 | unsigned off = iter->nameoff; | |
535 | ||
536 | iter->module_name[0] = '\0'; | |
537 | iter->value = kallsyms_sym_address(iter->pos); | |
538 | ||
539 | iter->type = kallsyms_get_symbol_type(off); | |
540 | ||
541 | off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name)); | |
542 | ||
543 | return off - iter->nameoff; | |
544 | } | |
545 | ||
546 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
547 | { | |
548 | iter->name[0] = '\0'; | |
549 | iter->nameoff = get_symbol_offset(new_pos); | |
550 | iter->pos = new_pos; | |
551 | if (new_pos == 0) { | |
552 | iter->pos_mod_end = 0; | |
553 | iter->pos_ftrace_mod_end = 0; | |
554 | } | |
555 | } | |
556 | ||
557 | static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) | |
558 | { | |
559 | iter->pos = pos; | |
560 | ||
561 | if (iter->pos_ftrace_mod_end > 0 && | |
562 | iter->pos_ftrace_mod_end < iter->pos) | |
563 | return get_ksymbol_bpf(iter); | |
564 | ||
565 | if (iter->pos_mod_end > 0 && | |
566 | iter->pos_mod_end < iter->pos) { | |
567 | if (!get_ksymbol_ftrace_mod(iter)) | |
568 | return get_ksymbol_bpf(iter); | |
569 | return 1; | |
570 | } | |
571 | ||
572 | if (!get_ksymbol_mod(iter)) { | |
573 | if (!get_ksymbol_ftrace_mod(iter)) | |
574 | return get_ksymbol_bpf(iter); | |
575 | } | |
576 | ||
577 | return 1; | |
578 | } | |
579 | ||
580 | /* Returns false if pos at or past end of file. */ | |
581 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
582 | { | |
583 | /* Module symbols can be accessed randomly. */ | |
584 | if (pos >= kallsyms_num_syms) | |
585 | return update_iter_mod(iter, pos); | |
586 | ||
587 | /* If we're not on the desired position, reset to new position. */ | |
588 | if (pos != iter->pos) | |
589 | reset_iter(iter, pos); | |
590 | ||
591 | iter->nameoff += get_ksymbol_core(iter); | |
592 | iter->pos++; | |
593 | ||
594 | return 1; | |
595 | } | |
596 | ||
597 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
598 | { | |
599 | (*pos)++; | |
600 | ||
601 | if (!update_iter(m->private, *pos)) | |
602 | return NULL; | |
603 | return p; | |
604 | } | |
605 | ||
606 | static void *s_start(struct seq_file *m, loff_t *pos) | |
607 | { | |
608 | if (!update_iter(m->private, *pos)) | |
609 | return NULL; | |
610 | return m->private; | |
611 | } | |
612 | ||
613 | static void s_stop(struct seq_file *m, void *p) | |
614 | { | |
615 | } | |
616 | ||
617 | static int s_show(struct seq_file *m, void *p) | |
618 | { | |
619 | void *value; | |
620 | struct kallsym_iter *iter = m->private; | |
621 | ||
622 | /* Some debugging symbols have no name. Ignore them. */ | |
623 | if (!iter->name[0]) | |
624 | return 0; | |
625 | ||
626 | value = iter->show_value ? (void *)iter->value : NULL; | |
627 | ||
628 | if (iter->module_name[0]) { | |
629 | char type; | |
630 | ||
631 | /* | |
632 | * Label it "global" if it is exported, | |
633 | * "local" if not exported. | |
634 | */ | |
635 | type = iter->exported ? toupper(iter->type) : | |
636 | tolower(iter->type); | |
637 | seq_printf(m, "%px %c %s\t[%s]\n", value, | |
638 | type, iter->name, iter->module_name); | |
639 | } else | |
640 | seq_printf(m, "%px %c %s\n", value, | |
641 | iter->type, iter->name); | |
642 | return 0; | |
643 | } | |
644 | ||
645 | static const struct seq_operations kallsyms_op = { | |
646 | .start = s_start, | |
647 | .next = s_next, | |
648 | .stop = s_stop, | |
649 | .show = s_show | |
650 | }; | |
651 | ||
652 | static inline int kallsyms_for_perf(void) | |
653 | { | |
654 | #ifdef CONFIG_PERF_EVENTS | |
655 | extern int sysctl_perf_event_paranoid; | |
656 | if (sysctl_perf_event_paranoid <= 1) | |
657 | return 1; | |
658 | #endif | |
659 | return 0; | |
660 | } | |
661 | ||
662 | /* | |
663 | * We show kallsyms information even to normal users if we've enabled | |
664 | * kernel profiling and are explicitly not paranoid (so kptr_restrict | |
665 | * is clear, and sysctl_perf_event_paranoid isn't set). | |
666 | * | |
667 | * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to | |
668 | * block even that). | |
669 | */ | |
670 | int kallsyms_show_value(void) | |
671 | { | |
672 | switch (kptr_restrict) { | |
673 | case 0: | |
674 | if (kallsyms_for_perf()) | |
675 | return 1; | |
676 | /* fallthrough */ | |
677 | case 1: | |
678 | if (has_capability_noaudit(current, CAP_SYSLOG)) | |
679 | return 1; | |
680 | /* fallthrough */ | |
681 | default: | |
682 | return 0; | |
683 | } | |
684 | } | |
685 | ||
686 | static int kallsyms_open(struct inode *inode, struct file *file) | |
687 | { | |
688 | /* | |
689 | * We keep iterator in m->private, since normal case is to | |
690 | * s_start from where we left off, so we avoid doing | |
691 | * using get_symbol_offset for every symbol. | |
692 | */ | |
693 | struct kallsym_iter *iter; | |
694 | iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter)); | |
695 | if (!iter) | |
696 | return -ENOMEM; | |
697 | reset_iter(iter, 0); | |
698 | ||
699 | iter->show_value = kallsyms_show_value(); | |
700 | return 0; | |
701 | } | |
702 | ||
703 | #ifdef CONFIG_KGDB_KDB | |
704 | const char *kdb_walk_kallsyms(loff_t *pos) | |
705 | { | |
706 | static struct kallsym_iter kdb_walk_kallsyms_iter; | |
707 | if (*pos == 0) { | |
708 | memset(&kdb_walk_kallsyms_iter, 0, | |
709 | sizeof(kdb_walk_kallsyms_iter)); | |
710 | reset_iter(&kdb_walk_kallsyms_iter, 0); | |
711 | } | |
712 | while (1) { | |
713 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) | |
714 | return NULL; | |
715 | ++*pos; | |
716 | /* Some debugging symbols have no name. Ignore them. */ | |
717 | if (kdb_walk_kallsyms_iter.name[0]) | |
718 | return kdb_walk_kallsyms_iter.name; | |
719 | } | |
720 | } | |
721 | #endif /* CONFIG_KGDB_KDB */ | |
722 | ||
723 | static const struct file_operations kallsyms_operations = { | |
724 | .open = kallsyms_open, | |
725 | .read = seq_read, | |
726 | .llseek = seq_lseek, | |
727 | .release = seq_release_private, | |
728 | }; | |
729 | ||
730 | static int __init kallsyms_init(void) | |
731 | { | |
732 | proc_create("kallsyms", 0444, NULL, &kallsyms_operations); | |
733 | return 0; | |
734 | } | |
735 | device_initcall(kallsyms_init); |