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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/compiler.h> | |
27 | ||
28 | #include <asm/sections.h> | |
29 | ||
30 | #ifdef CONFIG_KALLSYMS_ALL | |
31 | #define all_var 1 | |
32 | #else | |
33 | #define all_var 0 | |
34 | #endif | |
35 | ||
36 | /* | |
37 | * These will be re-linked against their real values | |
38 | * during the second link stage. | |
39 | */ | |
40 | extern const unsigned long kallsyms_addresses[] __weak; | |
41 | extern const u8 kallsyms_names[] __weak; | |
42 | ||
43 | /* | |
44 | * Tell the compiler that the count isn't in the small data section if the arch | |
45 | * has one (eg: FRV). | |
46 | */ | |
47 | extern const unsigned long kallsyms_num_syms | |
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 (all_var) | |
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 | /* Lookup the address for this symbol. Returns 0 if not found. */ | |
180 | unsigned long kallsyms_lookup_name(const char *name) | |
181 | { | |
182 | char namebuf[KSYM_NAME_LEN]; | |
183 | unsigned long i; | |
184 | unsigned int off; | |
185 | ||
186 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
187 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); | |
188 | ||
189 | if (strcmp(namebuf, name) == 0) | |
190 | return kallsyms_addresses[i]; | |
191 | } | |
192 | return module_kallsyms_lookup_name(name); | |
193 | } | |
194 | EXPORT_SYMBOL_GPL(kallsyms_lookup_name); | |
195 | ||
196 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, | |
197 | unsigned long), | |
198 | void *data) | |
199 | { | |
200 | char namebuf[KSYM_NAME_LEN]; | |
201 | unsigned long i; | |
202 | unsigned int off; | |
203 | int ret; | |
204 | ||
205 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
206 | off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); | |
207 | ret = fn(data, namebuf, NULL, kallsyms_addresses[i]); | |
208 | if (ret != 0) | |
209 | return ret; | |
210 | } | |
211 | return module_kallsyms_on_each_symbol(fn, data); | |
212 | } | |
213 | EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol); | |
214 | ||
215 | static unsigned long get_symbol_pos(unsigned long addr, | |
216 | unsigned long *symbolsize, | |
217 | unsigned long *offset) | |
218 | { | |
219 | unsigned long symbol_start = 0, symbol_end = 0; | |
220 | unsigned long i, low, high, mid; | |
221 | ||
222 | /* This kernel should never had been booted. */ | |
223 | BUG_ON(!kallsyms_addresses); | |
224 | ||
225 | /* Do a binary search on the sorted kallsyms_addresses array. */ | |
226 | low = 0; | |
227 | high = kallsyms_num_syms; | |
228 | ||
229 | while (high - low > 1) { | |
230 | mid = low + (high - low) / 2; | |
231 | if (kallsyms_addresses[mid] <= addr) | |
232 | low = mid; | |
233 | else | |
234 | high = mid; | |
235 | } | |
236 | ||
237 | /* | |
238 | * Search for the first aliased symbol. Aliased | |
239 | * symbols are symbols with the same address. | |
240 | */ | |
241 | while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low]) | |
242 | --low; | |
243 | ||
244 | symbol_start = kallsyms_addresses[low]; | |
245 | ||
246 | /* Search for next non-aliased symbol. */ | |
247 | for (i = low + 1; i < kallsyms_num_syms; i++) { | |
248 | if (kallsyms_addresses[i] > symbol_start) { | |
249 | symbol_end = kallsyms_addresses[i]; | |
250 | break; | |
251 | } | |
252 | } | |
253 | ||
254 | /* If we found no next symbol, we use the end of the section. */ | |
255 | if (!symbol_end) { | |
256 | if (is_kernel_inittext(addr)) | |
257 | symbol_end = (unsigned long)_einittext; | |
258 | else if (all_var) | |
259 | symbol_end = (unsigned long)_end; | |
260 | else | |
261 | symbol_end = (unsigned long)_etext; | |
262 | } | |
263 | ||
264 | if (symbolsize) | |
265 | *symbolsize = symbol_end - symbol_start; | |
266 | if (offset) | |
267 | *offset = addr - symbol_start; | |
268 | ||
269 | return low; | |
270 | } | |
271 | ||
272 | /* | |
273 | * Lookup an address but don't bother to find any names. | |
274 | */ | |
275 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, | |
276 | unsigned long *offset) | |
277 | { | |
278 | char namebuf[KSYM_NAME_LEN]; | |
279 | if (is_ksym_addr(addr)) | |
280 | return !!get_symbol_pos(addr, symbolsize, offset); | |
281 | ||
282 | return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf); | |
283 | } | |
284 | ||
285 | /* | |
286 | * Lookup an address | |
287 | * - modname is set to NULL if it's in the kernel. | |
288 | * - We guarantee that the returned name is valid until we reschedule even if. | |
289 | * It resides in a module. | |
290 | * - We also guarantee that modname will be valid until rescheduled. | |
291 | */ | |
292 | const char *kallsyms_lookup(unsigned long addr, | |
293 | unsigned long *symbolsize, | |
294 | unsigned long *offset, | |
295 | char **modname, char *namebuf) | |
296 | { | |
297 | namebuf[KSYM_NAME_LEN - 1] = 0; | |
298 | namebuf[0] = 0; | |
299 | ||
300 | if (is_ksym_addr(addr)) { | |
301 | unsigned long pos; | |
302 | ||
303 | pos = get_symbol_pos(addr, symbolsize, offset); | |
304 | /* Grab name */ | |
305 | kallsyms_expand_symbol(get_symbol_offset(pos), | |
306 | namebuf, KSYM_NAME_LEN); | |
307 | if (modname) | |
308 | *modname = NULL; | |
309 | return namebuf; | |
310 | } | |
311 | ||
312 | /* See if it's in a module. */ | |
313 | return module_address_lookup(addr, symbolsize, offset, modname, | |
314 | namebuf); | |
315 | } | |
316 | ||
317 | int lookup_symbol_name(unsigned long addr, char *symname) | |
318 | { | |
319 | symname[0] = '\0'; | |
320 | symname[KSYM_NAME_LEN - 1] = '\0'; | |
321 | ||
322 | if (is_ksym_addr(addr)) { | |
323 | unsigned long pos; | |
324 | ||
325 | pos = get_symbol_pos(addr, NULL, NULL); | |
326 | /* Grab name */ | |
327 | kallsyms_expand_symbol(get_symbol_offset(pos), | |
328 | symname, KSYM_NAME_LEN); | |
329 | return 0; | |
330 | } | |
331 | /* See if it's in a module. */ | |
332 | return lookup_module_symbol_name(addr, symname); | |
333 | } | |
334 | ||
335 | int lookup_symbol_attrs(unsigned long addr, unsigned long *size, | |
336 | unsigned long *offset, char *modname, char *name) | |
337 | { | |
338 | name[0] = '\0'; | |
339 | name[KSYM_NAME_LEN - 1] = '\0'; | |
340 | ||
341 | if (is_ksym_addr(addr)) { | |
342 | unsigned long pos; | |
343 | ||
344 | pos = get_symbol_pos(addr, size, offset); | |
345 | /* Grab name */ | |
346 | kallsyms_expand_symbol(get_symbol_offset(pos), | |
347 | name, KSYM_NAME_LEN); | |
348 | modname[0] = '\0'; | |
349 | return 0; | |
350 | } | |
351 | /* See if it's in a module. */ | |
352 | return lookup_module_symbol_attrs(addr, size, offset, modname, name); | |
353 | } | |
354 | ||
355 | /* Look up a kernel symbol and return it in a text buffer. */ | |
356 | static int __sprint_symbol(char *buffer, unsigned long address, | |
357 | int symbol_offset, int add_offset) | |
358 | { | |
359 | char *modname; | |
360 | const char *name; | |
361 | unsigned long offset, size; | |
362 | int len; | |
363 | ||
364 | address += symbol_offset; | |
365 | name = kallsyms_lookup(address, &size, &offset, &modname, buffer); | |
366 | if (!name) | |
367 | return sprintf(buffer, "0x%lx", address - symbol_offset); | |
368 | ||
369 | if (name != buffer) | |
370 | strcpy(buffer, name); | |
371 | len = strlen(buffer); | |
372 | offset -= symbol_offset; | |
373 | ||
374 | if (add_offset) | |
375 | len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); | |
376 | ||
377 | if (modname) | |
378 | len += sprintf(buffer + len, " [%s]", modname); | |
379 | ||
380 | return len; | |
381 | } | |
382 | ||
383 | /** | |
384 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer | |
385 | * @buffer: buffer to be stored | |
386 | * @address: address to lookup | |
387 | * | |
388 | * This function looks up a kernel symbol with @address and stores its name, | |
389 | * offset, size and module name to @buffer if possible. If no symbol was found, | |
390 | * just saves its @address as is. | |
391 | * | |
392 | * This function returns the number of bytes stored in @buffer. | |
393 | */ | |
394 | int sprint_symbol(char *buffer, unsigned long address) | |
395 | { | |
396 | return __sprint_symbol(buffer, address, 0, 1); | |
397 | } | |
398 | EXPORT_SYMBOL_GPL(sprint_symbol); | |
399 | ||
400 | /** | |
401 | * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer | |
402 | * @buffer: buffer to be stored | |
403 | * @address: address to lookup | |
404 | * | |
405 | * This function looks up a kernel symbol with @address and stores its name | |
406 | * and module name to @buffer if possible. If no symbol was found, just saves | |
407 | * its @address as is. | |
408 | * | |
409 | * This function returns the number of bytes stored in @buffer. | |
410 | */ | |
411 | int sprint_symbol_no_offset(char *buffer, unsigned long address) | |
412 | { | |
413 | return __sprint_symbol(buffer, address, 0, 0); | |
414 | } | |
415 | EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); | |
416 | ||
417 | /** | |
418 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer | |
419 | * @buffer: buffer to be stored | |
420 | * @address: address to lookup | |
421 | * | |
422 | * This function is for stack backtrace and does the same thing as | |
423 | * sprint_symbol() but with modified/decreased @address. If there is a | |
424 | * tail-call to the function marked "noreturn", gcc optimized out code after | |
425 | * the call so that the stack-saved return address could point outside of the | |
426 | * caller. This function ensures that kallsyms will find the original caller | |
427 | * by decreasing @address. | |
428 | * | |
429 | * This function returns the number of bytes stored in @buffer. | |
430 | */ | |
431 | int sprint_backtrace(char *buffer, unsigned long address) | |
432 | { | |
433 | return __sprint_symbol(buffer, address, -1, 1); | |
434 | } | |
435 | ||
436 | /* Look up a kernel symbol and print it to the kernel messages. */ | |
437 | void __print_symbol(const char *fmt, unsigned long address) | |
438 | { | |
439 | char buffer[KSYM_SYMBOL_LEN]; | |
440 | ||
441 | sprint_symbol(buffer, address); | |
442 | ||
443 | printk(fmt, buffer); | |
444 | } | |
445 | EXPORT_SYMBOL(__print_symbol); | |
446 | ||
447 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ | |
448 | struct kallsym_iter { | |
449 | loff_t pos; | |
450 | unsigned long value; | |
451 | unsigned int nameoff; /* If iterating in core kernel symbols. */ | |
452 | char type; | |
453 | char name[KSYM_NAME_LEN]; | |
454 | char module_name[MODULE_NAME_LEN]; | |
455 | int exported; | |
456 | }; | |
457 | ||
458 | static int get_ksymbol_mod(struct kallsym_iter *iter) | |
459 | { | |
460 | if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value, | |
461 | &iter->type, iter->name, iter->module_name, | |
462 | &iter->exported) < 0) | |
463 | return 0; | |
464 | return 1; | |
465 | } | |
466 | ||
467 | /* Returns space to next name. */ | |
468 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
469 | { | |
470 | unsigned off = iter->nameoff; | |
471 | ||
472 | iter->module_name[0] = '\0'; | |
473 | iter->value = kallsyms_addresses[iter->pos]; | |
474 | ||
475 | iter->type = kallsyms_get_symbol_type(off); | |
476 | ||
477 | off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name)); | |
478 | ||
479 | return off - iter->nameoff; | |
480 | } | |
481 | ||
482 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
483 | { | |
484 | iter->name[0] = '\0'; | |
485 | iter->nameoff = get_symbol_offset(new_pos); | |
486 | iter->pos = new_pos; | |
487 | } | |
488 | ||
489 | /* Returns false if pos at or past end of file. */ | |
490 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
491 | { | |
492 | /* Module symbols can be accessed randomly. */ | |
493 | if (pos >= kallsyms_num_syms) { | |
494 | iter->pos = pos; | |
495 | return get_ksymbol_mod(iter); | |
496 | } | |
497 | ||
498 | /* If we're not on the desired position, reset to new position. */ | |
499 | if (pos != iter->pos) | |
500 | reset_iter(iter, pos); | |
501 | ||
502 | iter->nameoff += get_ksymbol_core(iter); | |
503 | iter->pos++; | |
504 | ||
505 | return 1; | |
506 | } | |
507 | ||
508 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
509 | { | |
510 | (*pos)++; | |
511 | ||
512 | if (!update_iter(m->private, *pos)) | |
513 | return NULL; | |
514 | return p; | |
515 | } | |
516 | ||
517 | static void *s_start(struct seq_file *m, loff_t *pos) | |
518 | { | |
519 | if (!update_iter(m->private, *pos)) | |
520 | return NULL; | |
521 | return m->private; | |
522 | } | |
523 | ||
524 | static void s_stop(struct seq_file *m, void *p) | |
525 | { | |
526 | } | |
527 | ||
528 | static int s_show(struct seq_file *m, void *p) | |
529 | { | |
530 | struct kallsym_iter *iter = m->private; | |
531 | ||
532 | /* Some debugging symbols have no name. Ignore them. */ | |
533 | if (!iter->name[0]) | |
534 | return 0; | |
535 | ||
536 | if (iter->module_name[0]) { | |
537 | char type; | |
538 | ||
539 | /* | |
540 | * Label it "global" if it is exported, | |
541 | * "local" if not exported. | |
542 | */ | |
543 | type = iter->exported ? toupper(iter->type) : | |
544 | tolower(iter->type); | |
545 | seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value, | |
546 | type, iter->name, iter->module_name); | |
547 | } else | |
548 | seq_printf(m, "%pK %c %s\n", (void *)iter->value, | |
549 | iter->type, iter->name); | |
550 | return 0; | |
551 | } | |
552 | ||
553 | static const struct seq_operations kallsyms_op = { | |
554 | .start = s_start, | |
555 | .next = s_next, | |
556 | .stop = s_stop, | |
557 | .show = s_show | |
558 | }; | |
559 | ||
560 | static int kallsyms_open(struct inode *inode, struct file *file) | |
561 | { | |
562 | /* | |
563 | * We keep iterator in m->private, since normal case is to | |
564 | * s_start from where we left off, so we avoid doing | |
565 | * using get_symbol_offset for every symbol. | |
566 | */ | |
567 | struct kallsym_iter *iter; | |
568 | iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter)); | |
569 | if (!iter) | |
570 | return -ENOMEM; | |
571 | reset_iter(iter, 0); | |
572 | ||
573 | return 0; | |
574 | } | |
575 | ||
576 | #ifdef CONFIG_KGDB_KDB | |
577 | const char *kdb_walk_kallsyms(loff_t *pos) | |
578 | { | |
579 | static struct kallsym_iter kdb_walk_kallsyms_iter; | |
580 | if (*pos == 0) { | |
581 | memset(&kdb_walk_kallsyms_iter, 0, | |
582 | sizeof(kdb_walk_kallsyms_iter)); | |
583 | reset_iter(&kdb_walk_kallsyms_iter, 0); | |
584 | } | |
585 | while (1) { | |
586 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) | |
587 | return NULL; | |
588 | ++*pos; | |
589 | /* Some debugging symbols have no name. Ignore them. */ | |
590 | if (kdb_walk_kallsyms_iter.name[0]) | |
591 | return kdb_walk_kallsyms_iter.name; | |
592 | } | |
593 | } | |
594 | #endif /* CONFIG_KGDB_KDB */ | |
595 | ||
596 | static const struct file_operations kallsyms_operations = { | |
597 | .open = kallsyms_open, | |
598 | .read = seq_read, | |
599 | .llseek = seq_lseek, | |
600 | .release = seq_release_private, | |
601 | }; | |
602 | ||
603 | static int __init kallsyms_init(void) | |
604 | { | |
605 | proc_create("kallsyms", 0444, NULL, &kallsyms_operations); | |
606 | return 0; | |
607 | } | |
608 | device_initcall(kallsyms_init); |