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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 | |
27 | #include <asm/sections.h> |
28 | |
29 | #ifdef CONFIG_KALLSYMS_ALL |
30 | #define all_var 1 |
31 | #else |
32 | #define all_var 0 |
33 | #endif |
34 | |
35 | /* |
36 | * These will be re-linked against their real values |
37 | * during the second link stage. |
38 | */ |
39 | extern const unsigned long kallsyms_addresses[] __attribute__((weak)); |
40 | extern const u8 kallsyms_names[] __attribute__((weak)); |
41 | |
42 | /* |
43 | * Tell the compiler that the count isn't in the small data section if the arch |
44 | * has one (eg: FRV). |
45 | */ |
46 | extern const unsigned long kallsyms_num_syms |
47 | __attribute__((weak, section(".rodata"))); |
48 | |
49 | extern const u8 kallsyms_token_table[] __attribute__((weak)); |
50 | extern const u16 kallsyms_token_index[] __attribute__((weak)); |
51 | |
52 | extern const unsigned long kallsyms_markers[] __attribute__((weak)); |
53 | |
54 | static inline int is_kernel_inittext(unsigned long addr) |
55 | { |
56 | if (addr >= (unsigned long)_sinittext |
57 | && addr <= (unsigned long)_einittext) |
58 | return 1; |
59 | return 0; |
60 | } |
61 | |
62 | static inline int is_kernel_text(unsigned long addr) |
63 | { |
64 | if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) || |
65 | arch_is_kernel_text(addr)) |
66 | return 1; |
67 | return in_gate_area_no_mm(addr); |
68 | } |
69 | |
70 | static inline int is_kernel(unsigned long addr) |
71 | { |
72 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) |
73 | return 1; |
74 | return in_gate_area_no_mm(addr); |
75 | } |
76 | |
77 | static int is_ksym_addr(unsigned long addr) |
78 | { |
79 | if (all_var) |
80 | return is_kernel(addr); |
81 | |
82 | return is_kernel_text(addr) || is_kernel_inittext(addr); |
83 | } |
84 | |
85 | /* |
86 | * Expand a compressed symbol data into the resulting uncompressed string, |
87 | * given the offset to where the symbol is in the compressed stream. |
88 | */ |
89 | static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) |
90 | { |
91 | int len, skipped_first = 0; |
92 | const u8 *tptr, *data; |
93 | |
94 | /* Get the compressed symbol length from the first symbol byte. */ |
95 | data = &kallsyms_names[off]; |
96 | len = *data; |
97 | data++; |
98 | |
99 | /* |
100 | * Update the offset to return the offset for the next symbol on |
101 | * the compressed stream. |
102 | */ |
103 | off += len + 1; |
104 | |
105 | /* |
106 | * For every byte on the compressed symbol data, copy the table |
107 | * entry for that byte. |
108 | */ |
109 | while (len) { |
110 | tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; |
111 | data++; |
112 | len--; |
113 | |
114 | while (*tptr) { |
115 | if (skipped_first) { |
116 | *result = *tptr; |
117 | result++; |
118 | } else |
119 | skipped_first = 1; |
120 | tptr++; |
121 | } |
122 | } |
123 | |
124 | *result = '\0'; |
125 | |
126 | /* Return to offset to the next symbol. */ |
127 | return off; |
128 | } |
129 | |
130 | /* |
131 | * Get symbol type information. This is encoded as a single char at the |
132 | * beginning of the symbol name. |
133 | */ |
134 | static char kallsyms_get_symbol_type(unsigned int off) |
135 | { |
136 | /* |
137 | * Get just the first code, look it up in the token table, |
138 | * and return the first char from this token. |
139 | */ |
140 | return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; |
141 | } |
142 | |
143 | |
144 | /* |
145 | * Find the offset on the compressed stream given and index in the |
146 | * kallsyms array. |
147 | */ |
148 | static unsigned int get_symbol_offset(unsigned long pos) |
149 | { |
150 | const u8 *name; |
151 | int i; |
152 | |
153 | /* |
154 | * Use the closest marker we have. We have markers every 256 positions, |
155 | * so that should be close enough. |
156 | */ |
157 | name = &kallsyms_names[kallsyms_markers[pos >> 8]]; |
158 | |
159 | /* |
160 | * Sequentially scan all the symbols up to the point we're searching |
161 | * for. Every symbol is stored in a [<len>][<len> bytes of data] format, |
162 | * so we just need to add the len to the current pointer for every |
163 | * symbol we wish to skip. |
164 | */ |
165 | for (i = 0; i < (pos & 0xFF); i++) |
166 | name = name + (*name) + 1; |
167 | |
168 | return name - kallsyms_names; |
169 | } |
170 | |
171 | /* Lookup the address for this symbol. Returns 0 if not found. */ |
172 | unsigned long kallsyms_lookup_name(const char *name) |
173 | { |
174 | char namebuf[KSYM_NAME_LEN]; |
175 | unsigned long i; |
176 | unsigned int off; |
177 | |
178 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
179 | off = kallsyms_expand_symbol(off, namebuf); |
180 | |
181 | if (strcmp(namebuf, name) == 0) |
182 | return kallsyms_addresses[i]; |
183 | } |
184 | return module_kallsyms_lookup_name(name); |
185 | } |
186 | EXPORT_SYMBOL_GPL(kallsyms_lookup_name); |
187 | |
188 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, |
189 | unsigned long), |
190 | void *data) |
191 | { |
192 | char namebuf[KSYM_NAME_LEN]; |
193 | unsigned long i; |
194 | unsigned int off; |
195 | int ret; |
196 | |
197 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
198 | off = kallsyms_expand_symbol(off, namebuf); |
199 | ret = fn(data, namebuf, NULL, kallsyms_addresses[i]); |
200 | if (ret != 0) |
201 | return ret; |
202 | } |
203 | return module_kallsyms_on_each_symbol(fn, data); |
204 | } |
205 | EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol); |
206 | |
207 | static unsigned long get_symbol_pos(unsigned long addr, |
208 | unsigned long *symbolsize, |
209 | unsigned long *offset) |
210 | { |
211 | unsigned long symbol_start = 0, symbol_end = 0; |
212 | unsigned long i, low, high, mid; |
213 | |
214 | /* This kernel should never had been booted. */ |
215 | BUG_ON(!kallsyms_addresses); |
216 | |
217 | /* Do a binary search on the sorted kallsyms_addresses array. */ |
218 | low = 0; |
219 | high = kallsyms_num_syms; |
220 | |
221 | while (high - low > 1) { |
222 | mid = low + (high - low) / 2; |
223 | if (kallsyms_addresses[mid] <= addr) |
224 | low = mid; |
225 | else |
226 | high = mid; |
227 | } |
228 | |
229 | /* |
230 | * Search for the first aliased symbol. Aliased |
231 | * symbols are symbols with the same address. |
232 | */ |
233 | while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low]) |
234 | --low; |
235 | |
236 | symbol_start = kallsyms_addresses[low]; |
237 | |
238 | /* Search for next non-aliased symbol. */ |
239 | for (i = low + 1; i < kallsyms_num_syms; i++) { |
240 | if (kallsyms_addresses[i] > symbol_start) { |
241 | symbol_end = kallsyms_addresses[i]; |
242 | break; |
243 | } |
244 | } |
245 | |
246 | /* If we found no next symbol, we use the end of the section. */ |
247 | if (!symbol_end) { |
248 | if (is_kernel_inittext(addr)) |
249 | symbol_end = (unsigned long)_einittext; |
250 | else if (all_var) |
251 | symbol_end = (unsigned long)_end; |
252 | else |
253 | symbol_end = (unsigned long)_etext; |
254 | } |
255 | |
256 | if (symbolsize) |
257 | *symbolsize = symbol_end - symbol_start; |
258 | if (offset) |
259 | *offset = addr - symbol_start; |
260 | |
261 | return low; |
262 | } |
263 | |
264 | /* |
265 | * Lookup an address but don't bother to find any names. |
266 | */ |
267 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, |
268 | unsigned long *offset) |
269 | { |
270 | char namebuf[KSYM_NAME_LEN]; |
271 | if (is_ksym_addr(addr)) |
272 | return !!get_symbol_pos(addr, symbolsize, offset); |
273 | |
274 | return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf); |
275 | } |
276 | |
277 | /* |
278 | * Lookup an address |
279 | * - modname is set to NULL if it's in the kernel. |
280 | * - We guarantee that the returned name is valid until we reschedule even if. |
281 | * It resides in a module. |
282 | * - We also guarantee that modname will be valid until rescheduled. |
283 | */ |
284 | const char *kallsyms_lookup(unsigned long addr, |
285 | unsigned long *symbolsize, |
286 | unsigned long *offset, |
287 | char **modname, char *namebuf) |
288 | { |
289 | namebuf[KSYM_NAME_LEN - 1] = 0; |
290 | namebuf[0] = 0; |
291 | |
292 | if (is_ksym_addr(addr)) { |
293 | unsigned long pos; |
294 | |
295 | pos = get_symbol_pos(addr, symbolsize, offset); |
296 | /* Grab name */ |
297 | kallsyms_expand_symbol(get_symbol_offset(pos), namebuf); |
298 | if (modname) |
299 | *modname = NULL; |
300 | return namebuf; |
301 | } |
302 | |
303 | /* See if it's in a module. */ |
304 | return module_address_lookup(addr, symbolsize, offset, modname, |
305 | namebuf); |
306 | } |
307 | |
308 | int lookup_symbol_name(unsigned long addr, char *symname) |
309 | { |
310 | symname[0] = '\0'; |
311 | symname[KSYM_NAME_LEN - 1] = '\0'; |
312 | |
313 | if (is_ksym_addr(addr)) { |
314 | unsigned long pos; |
315 | |
316 | pos = get_symbol_pos(addr, NULL, NULL); |
317 | /* Grab name */ |
318 | kallsyms_expand_symbol(get_symbol_offset(pos), symname); |
319 | return 0; |
320 | } |
321 | /* See if it's in a module. */ |
322 | return lookup_module_symbol_name(addr, symname); |
323 | } |
324 | |
325 | int lookup_symbol_attrs(unsigned long addr, unsigned long *size, |
326 | unsigned long *offset, char *modname, char *name) |
327 | { |
328 | name[0] = '\0'; |
329 | name[KSYM_NAME_LEN - 1] = '\0'; |
330 | |
331 | if (is_ksym_addr(addr)) { |
332 | unsigned long pos; |
333 | |
334 | pos = get_symbol_pos(addr, size, offset); |
335 | /* Grab name */ |
336 | kallsyms_expand_symbol(get_symbol_offset(pos), name); |
337 | modname[0] = '\0'; |
338 | return 0; |
339 | } |
340 | /* See if it's in a module. */ |
341 | return lookup_module_symbol_attrs(addr, size, offset, modname, name); |
342 | } |
343 | |
344 | /* Look up a kernel symbol and return it in a text buffer. */ |
345 | static int __sprint_symbol(char *buffer, unsigned long address, |
346 | int symbol_offset, int add_offset) |
347 | { |
348 | char *modname; |
349 | const char *name; |
350 | unsigned long offset, size; |
351 | int len; |
352 | |
353 | address += symbol_offset; |
354 | name = kallsyms_lookup(address, &size, &offset, &modname, buffer); |
355 | if (!name) |
356 | return sprintf(buffer, "0x%lx", address); |
357 | |
358 | if (name != buffer) |
359 | strcpy(buffer, name); |
360 | len = strlen(buffer); |
361 | offset -= symbol_offset; |
362 | |
363 | if (add_offset) |
364 | len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); |
365 | |
366 | if (modname) |
367 | len += sprintf(buffer + len, " [%s]", modname); |
368 | |
369 | return len; |
370 | } |
371 | |
372 | /** |
373 | * sprint_symbol - Look up a kernel symbol and return it in a text buffer |
374 | * @buffer: buffer to be stored |
375 | * @address: address to lookup |
376 | * |
377 | * This function looks up a kernel symbol with @address and stores its name, |
378 | * offset, size and module name to @buffer if possible. If no symbol was found, |
379 | * just saves its @address as is. |
380 | * |
381 | * This function returns the number of bytes stored in @buffer. |
382 | */ |
383 | int sprint_symbol(char *buffer, unsigned long address) |
384 | { |
385 | return __sprint_symbol(buffer, address, 0, 1); |
386 | } |
387 | EXPORT_SYMBOL_GPL(sprint_symbol); |
388 | |
389 | /** |
390 | * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer |
391 | * @buffer: buffer to be stored |
392 | * @address: address to lookup |
393 | * |
394 | * This function looks up a kernel symbol with @address and stores its name |
395 | * and module name to @buffer if possible. If no symbol was found, just saves |
396 | * its @address as is. |
397 | * |
398 | * This function returns the number of bytes stored in @buffer. |
399 | */ |
400 | int sprint_symbol_no_offset(char *buffer, unsigned long address) |
401 | { |
402 | return __sprint_symbol(buffer, address, 0, 0); |
403 | } |
404 | EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); |
405 | |
406 | /** |
407 | * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer |
408 | * @buffer: buffer to be stored |
409 | * @address: address to lookup |
410 | * |
411 | * This function is for stack backtrace and does the same thing as |
412 | * sprint_symbol() but with modified/decreased @address. If there is a |
413 | * tail-call to the function marked "noreturn", gcc optimized out code after |
414 | * the call so that the stack-saved return address could point outside of the |
415 | * caller. This function ensures that kallsyms will find the original caller |
416 | * by decreasing @address. |
417 | * |
418 | * This function returns the number of bytes stored in @buffer. |
419 | */ |
420 | int sprint_backtrace(char *buffer, unsigned long address) |
421 | { |
422 | return __sprint_symbol(buffer, address, -1, 1); |
423 | } |
424 | |
425 | /* Look up a kernel symbol and print it to the kernel messages. */ |
426 | void __print_symbol(const char *fmt, unsigned long address) |
427 | { |
428 | char buffer[KSYM_SYMBOL_LEN]; |
429 | |
430 | sprint_symbol(buffer, address); |
431 | |
432 | printk(fmt, buffer); |
433 | } |
434 | EXPORT_SYMBOL(__print_symbol); |
435 | |
436 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ |
437 | struct kallsym_iter { |
438 | loff_t pos; |
439 | unsigned long value; |
440 | unsigned int nameoff; /* If iterating in core kernel symbols. */ |
441 | char type; |
442 | char name[KSYM_NAME_LEN]; |
443 | char module_name[MODULE_NAME_LEN]; |
444 | int exported; |
445 | }; |
446 | |
447 | static int get_ksymbol_mod(struct kallsym_iter *iter) |
448 | { |
449 | if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value, |
450 | &iter->type, iter->name, iter->module_name, |
451 | &iter->exported) < 0) |
452 | return 0; |
453 | return 1; |
454 | } |
455 | |
456 | /* Returns space to next name. */ |
457 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) |
458 | { |
459 | unsigned off = iter->nameoff; |
460 | |
461 | iter->module_name[0] = '\0'; |
462 | iter->value = kallsyms_addresses[iter->pos]; |
463 | |
464 | iter->type = kallsyms_get_symbol_type(off); |
465 | |
466 | off = kallsyms_expand_symbol(off, iter->name); |
467 | |
468 | return off - iter->nameoff; |
469 | } |
470 | |
471 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) |
472 | { |
473 | iter->name[0] = '\0'; |
474 | iter->nameoff = get_symbol_offset(new_pos); |
475 | iter->pos = new_pos; |
476 | } |
477 | |
478 | /* Returns false if pos at or past end of file. */ |
479 | static int update_iter(struct kallsym_iter *iter, loff_t pos) |
480 | { |
481 | /* Module symbols can be accessed randomly. */ |
482 | if (pos >= kallsyms_num_syms) { |
483 | iter->pos = pos; |
484 | return get_ksymbol_mod(iter); |
485 | } |
486 | |
487 | /* If we're not on the desired position, reset to new position. */ |
488 | if (pos != iter->pos) |
489 | reset_iter(iter, pos); |
490 | |
491 | iter->nameoff += get_ksymbol_core(iter); |
492 | iter->pos++; |
493 | |
494 | return 1; |
495 | } |
496 | |
497 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) |
498 | { |
499 | (*pos)++; |
500 | |
501 | if (!update_iter(m->private, *pos)) |
502 | return NULL; |
503 | return p; |
504 | } |
505 | |
506 | static void *s_start(struct seq_file *m, loff_t *pos) |
507 | { |
508 | if (!update_iter(m->private, *pos)) |
509 | return NULL; |
510 | return m->private; |
511 | } |
512 | |
513 | static void s_stop(struct seq_file *m, void *p) |
514 | { |
515 | } |
516 | |
517 | static int s_show(struct seq_file *m, void *p) |
518 | { |
519 | struct kallsym_iter *iter = m->private; |
520 | |
521 | /* Some debugging symbols have no name. Ignore them. */ |
522 | if (!iter->name[0]) |
523 | return 0; |
524 | |
525 | if (iter->module_name[0]) { |
526 | char type; |
527 | |
528 | /* |
529 | * Label it "global" if it is exported, |
530 | * "local" if not exported. |
531 | */ |
532 | type = iter->exported ? toupper(iter->type) : |
533 | tolower(iter->type); |
534 | seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value, |
535 | type, iter->name, iter->module_name); |
536 | } else |
537 | seq_printf(m, "%pK %c %s\n", (void *)iter->value, |
538 | iter->type, iter->name); |
539 | return 0; |
540 | } |
541 | |
542 | static const struct seq_operations kallsyms_op = { |
543 | .start = s_start, |
544 | .next = s_next, |
545 | .stop = s_stop, |
546 | .show = s_show |
547 | }; |
548 | |
549 | static int kallsyms_open(struct inode *inode, struct file *file) |
550 | { |
551 | /* |
552 | * We keep iterator in m->private, since normal case is to |
553 | * s_start from where we left off, so we avoid doing |
554 | * using get_symbol_offset for every symbol. |
555 | */ |
556 | struct kallsym_iter *iter; |
557 | int ret; |
558 | |
559 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); |
560 | if (!iter) |
561 | return -ENOMEM; |
562 | reset_iter(iter, 0); |
563 | |
564 | ret = seq_open(file, &kallsyms_op); |
565 | if (ret == 0) |
566 | ((struct seq_file *)file->private_data)->private = iter; |
567 | else |
568 | kfree(iter); |
569 | return ret; |
570 | } |
571 | |
572 | #ifdef CONFIG_KGDB_KDB |
573 | const char *kdb_walk_kallsyms(loff_t *pos) |
574 | { |
575 | static struct kallsym_iter kdb_walk_kallsyms_iter; |
576 | if (*pos == 0) { |
577 | memset(&kdb_walk_kallsyms_iter, 0, |
578 | sizeof(kdb_walk_kallsyms_iter)); |
579 | reset_iter(&kdb_walk_kallsyms_iter, 0); |
580 | } |
581 | while (1) { |
582 | if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) |
583 | return NULL; |
584 | ++*pos; |
585 | /* Some debugging symbols have no name. Ignore them. */ |
586 | if (kdb_walk_kallsyms_iter.name[0]) |
587 | return kdb_walk_kallsyms_iter.name; |
588 | } |
589 | } |
590 | #endif /* CONFIG_KGDB_KDB */ |
591 | |
592 | static const struct file_operations kallsyms_operations = { |
593 | .open = kallsyms_open, |
594 | .read = seq_read, |
595 | .llseek = seq_lseek, |
596 | .release = seq_release_private, |
597 | }; |
598 | |
599 | static int __init kallsyms_init(void) |
600 | { |
601 | proc_create("kallsyms", 0444, NULL, &kallsyms_operations); |
602 | return 0; |
603 | } |
604 | device_initcall(kallsyms_init); |
605 |
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