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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/err.h> |
20 | #include <linux/proc_fs.h> |
21 | #include <linux/sched.h> /* for cond_resched */ |
22 | #include <linux/mm.h> |
23 | #include <linux/ctype.h> |
24 | #include <linux/slab.h> |
25 | |
26 | #include <asm/sections.h> |
27 | |
28 | #ifdef CONFIG_KALLSYMS_ALL |
29 | #define all_var 1 |
30 | #else |
31 | #define all_var 0 |
32 | #endif |
33 | |
34 | /* |
35 | * These will be re-linked against their real values |
36 | * during the second link stage. |
37 | */ |
38 | extern const unsigned long kallsyms_addresses[] __attribute__((weak)); |
39 | extern const u8 kallsyms_names[] __attribute__((weak)); |
40 | |
41 | /* |
42 | * Tell the compiler that the count isn't in the small data section if the arch |
43 | * has one (eg: FRV). |
44 | */ |
45 | extern const unsigned long kallsyms_num_syms |
46 | __attribute__((weak, section(".rodata"))); |
47 | |
48 | extern const u8 kallsyms_token_table[] __attribute__((weak)); |
49 | extern const u16 kallsyms_token_index[] __attribute__((weak)); |
50 | |
51 | extern const unsigned long kallsyms_markers[] __attribute__((weak)); |
52 | |
53 | static inline int is_kernel_inittext(unsigned long addr) |
54 | { |
55 | if (addr >= (unsigned long)_sinittext |
56 | && addr <= (unsigned long)_einittext) |
57 | return 1; |
58 | return 0; |
59 | } |
60 | |
61 | static inline int is_kernel_text(unsigned long addr) |
62 | { |
63 | if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) || |
64 | arch_is_kernel_text(addr)) |
65 | return 1; |
66 | return in_gate_area_no_task(addr); |
67 | } |
68 | |
69 | static inline int is_kernel(unsigned long addr) |
70 | { |
71 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) |
72 | return 1; |
73 | return in_gate_area_no_task(addr); |
74 | } |
75 | |
76 | static int is_ksym_addr(unsigned long addr) |
77 | { |
78 | if (all_var) |
79 | return is_kernel(addr); |
80 | |
81 | return is_kernel_text(addr) || is_kernel_inittext(addr); |
82 | } |
83 | |
84 | /* |
85 | * Expand a compressed symbol data into the resulting uncompressed string, |
86 | * given the offset to where the symbol is in the compressed stream. |
87 | */ |
88 | static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) |
89 | { |
90 | int len, skipped_first = 0; |
91 | const u8 *tptr, *data; |
92 | |
93 | /* Get the compressed symbol length from the first symbol byte. */ |
94 | data = &kallsyms_names[off]; |
95 | len = *data; |
96 | data++; |
97 | |
98 | /* |
99 | * Update the offset to return the offset for the next symbol on |
100 | * the compressed stream. |
101 | */ |
102 | off += len + 1; |
103 | |
104 | /* |
105 | * For every byte on the compressed symbol data, copy the table |
106 | * entry for that byte. |
107 | */ |
108 | while (len) { |
109 | tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; |
110 | data++; |
111 | len--; |
112 | |
113 | while (*tptr) { |
114 | if (skipped_first) { |
115 | *result = *tptr; |
116 | result++; |
117 | } else |
118 | skipped_first = 1; |
119 | tptr++; |
120 | } |
121 | } |
122 | |
123 | *result = '\0'; |
124 | |
125 | /* Return to offset to the next symbol. */ |
126 | return off; |
127 | } |
128 | |
129 | /* |
130 | * Get symbol type information. This is encoded as a single char at the |
131 | * beginning of the symbol name. |
132 | */ |
133 | static char kallsyms_get_symbol_type(unsigned int off) |
134 | { |
135 | /* |
136 | * Get just the first code, look it up in the token table, |
137 | * and return the first char from this token. |
138 | */ |
139 | return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; |
140 | } |
141 | |
142 | |
143 | /* |
144 | * Find the offset on the compressed stream given and index in the |
145 | * kallsyms array. |
146 | */ |
147 | static unsigned int get_symbol_offset(unsigned long pos) |
148 | { |
149 | const u8 *name; |
150 | int i; |
151 | |
152 | /* |
153 | * Use the closest marker we have. We have markers every 256 positions, |
154 | * so that should be close enough. |
155 | */ |
156 | name = &kallsyms_names[kallsyms_markers[pos >> 8]]; |
157 | |
158 | /* |
159 | * Sequentially scan all the symbols up to the point we're searching |
160 | * for. Every symbol is stored in a [<len>][<len> bytes of data] format, |
161 | * so we just need to add the len to the current pointer for every |
162 | * symbol we wish to skip. |
163 | */ |
164 | for (i = 0; i < (pos & 0xFF); i++) |
165 | name = name + (*name) + 1; |
166 | |
167 | return name - kallsyms_names; |
168 | } |
169 | |
170 | /* Lookup the address for this symbol. Returns 0 if not found. */ |
171 | unsigned long kallsyms_lookup_name(const char *name) |
172 | { |
173 | char namebuf[KSYM_NAME_LEN]; |
174 | unsigned long i; |
175 | unsigned int off; |
176 | |
177 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
178 | off = kallsyms_expand_symbol(off, namebuf); |
179 | |
180 | if (strcmp(namebuf, name) == 0) |
181 | return kallsyms_addresses[i]; |
182 | } |
183 | return module_kallsyms_lookup_name(name); |
184 | } |
185 | EXPORT_SYMBOL_GPL(kallsyms_lookup_name); |
186 | |
187 | int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, |
188 | unsigned long), |
189 | void *data) |
190 | { |
191 | char namebuf[KSYM_NAME_LEN]; |
192 | unsigned long i; |
193 | unsigned int off; |
194 | int ret; |
195 | |
196 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
197 | off = kallsyms_expand_symbol(off, namebuf); |
198 | ret = fn(data, namebuf, NULL, kallsyms_addresses[i]); |
199 | if (ret != 0) |
200 | return ret; |
201 | } |
202 | return module_kallsyms_on_each_symbol(fn, data); |
203 | } |
204 | EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol); |
205 | |
206 | static unsigned long get_symbol_pos(unsigned long addr, |
207 | unsigned long *symbolsize, |
208 | unsigned long *offset) |
209 | { |
210 | unsigned long symbol_start = 0, symbol_end = 0; |
211 | unsigned long i, low, high, mid; |
212 | |
213 | /* This kernel should never had been booted. */ |
214 | BUG_ON(!kallsyms_addresses); |
215 | |
216 | /* Do a binary search on the sorted kallsyms_addresses array. */ |
217 | low = 0; |
218 | high = kallsyms_num_syms; |
219 | |
220 | while (high - low > 1) { |
221 | mid = low + (high - low) / 2; |
222 | if (kallsyms_addresses[mid] <= addr) |
223 | low = mid; |
224 | else |
225 | high = mid; |
226 | } |
227 | |
228 | /* |
229 | * Search for the first aliased symbol. Aliased |
230 | * symbols are symbols with the same address. |
231 | */ |
232 | while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low]) |
233 | --low; |
234 | |
235 | symbol_start = kallsyms_addresses[low]; |
236 | |
237 | /* Search for next non-aliased symbol. */ |
238 | for (i = low + 1; i < kallsyms_num_syms; i++) { |
239 | if (kallsyms_addresses[i] > symbol_start) { |
240 | symbol_end = kallsyms_addresses[i]; |
241 | break; |
242 | } |
243 | } |
244 | |
245 | /* If we found no next symbol, we use the end of the section. */ |
246 | if (!symbol_end) { |
247 | if (is_kernel_inittext(addr)) |
248 | symbol_end = (unsigned long)_einittext; |
249 | else if (all_var) |
250 | symbol_end = (unsigned long)_end; |
251 | else |
252 | symbol_end = (unsigned long)_etext; |
253 | } |
254 | |
255 | if (symbolsize) |
256 | *symbolsize = symbol_end - symbol_start; |
257 | if (offset) |
258 | *offset = addr - symbol_start; |
259 | |
260 | return low; |
261 | } |
262 | |
263 | /* |
264 | * Lookup an address but don't bother to find any names. |
265 | */ |
266 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, |
267 | unsigned long *offset) |
268 | { |
269 | char namebuf[KSYM_NAME_LEN]; |
270 | if (is_ksym_addr(addr)) |
271 | return !!get_symbol_pos(addr, symbolsize, offset); |
272 | |
273 | return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf); |
274 | } |
275 | |
276 | /* |
277 | * Lookup an address |
278 | * - modname is set to NULL if it's in the kernel. |
279 | * - We guarantee that the returned name is valid until we reschedule even if. |
280 | * It resides in a module. |
281 | * - We also guarantee that modname will be valid until rescheduled. |
282 | */ |
283 | const char *kallsyms_lookup(unsigned long addr, |
284 | unsigned long *symbolsize, |
285 | unsigned long *offset, |
286 | char **modname, char *namebuf) |
287 | { |
288 | namebuf[KSYM_NAME_LEN - 1] = 0; |
289 | namebuf[0] = 0; |
290 | |
291 | if (is_ksym_addr(addr)) { |
292 | unsigned long pos; |
293 | |
294 | pos = get_symbol_pos(addr, symbolsize, offset); |
295 | /* Grab name */ |
296 | kallsyms_expand_symbol(get_symbol_offset(pos), namebuf); |
297 | if (modname) |
298 | *modname = NULL; |
299 | return namebuf; |
300 | } |
301 | |
302 | /* See if it's in a module. */ |
303 | return module_address_lookup(addr, symbolsize, offset, modname, |
304 | namebuf); |
305 | } |
306 | |
307 | int lookup_symbol_name(unsigned long addr, char *symname) |
308 | { |
309 | symname[0] = '\0'; |
310 | symname[KSYM_NAME_LEN - 1] = '\0'; |
311 | |
312 | if (is_ksym_addr(addr)) { |
313 | unsigned long pos; |
314 | |
315 | pos = get_symbol_pos(addr, NULL, NULL); |
316 | /* Grab name */ |
317 | kallsyms_expand_symbol(get_symbol_offset(pos), symname); |
318 | return 0; |
319 | } |
320 | /* See if it's in a module. */ |
321 | return lookup_module_symbol_name(addr, symname); |
322 | } |
323 | |
324 | int lookup_symbol_attrs(unsigned long addr, unsigned long *size, |
325 | unsigned long *offset, char *modname, char *name) |
326 | { |
327 | name[0] = '\0'; |
328 | name[KSYM_NAME_LEN - 1] = '\0'; |
329 | |
330 | if (is_ksym_addr(addr)) { |
331 | unsigned long pos; |
332 | |
333 | pos = get_symbol_pos(addr, size, offset); |
334 | /* Grab name */ |
335 | kallsyms_expand_symbol(get_symbol_offset(pos), name); |
336 | modname[0] = '\0'; |
337 | return 0; |
338 | } |
339 | /* See if it's in a module. */ |
340 | return lookup_module_symbol_attrs(addr, size, offset, modname, name); |
341 | } |
342 | |
343 | /* Look up a kernel symbol and return it in a text buffer. */ |
344 | int sprint_symbol(char *buffer, unsigned long address) |
345 | { |
346 | char *modname; |
347 | const char *name; |
348 | unsigned long offset, size; |
349 | int len; |
350 | |
351 | name = kallsyms_lookup(address, &size, &offset, &modname, buffer); |
352 | if (!name) |
353 | return sprintf(buffer, "0x%lx", address); |
354 | |
355 | if (name != buffer) |
356 | strcpy(buffer, name); |
357 | len = strlen(buffer); |
358 | buffer += len; |
359 | |
360 | if (modname) |
361 | len += sprintf(buffer, "+%#lx/%#lx [%s]", |
362 | offset, size, modname); |
363 | else |
364 | len += sprintf(buffer, "+%#lx/%#lx", offset, size); |
365 | |
366 | return len; |
367 | } |
368 | EXPORT_SYMBOL_GPL(sprint_symbol); |
369 | |
370 | /* Look up a kernel symbol and print it to the kernel messages. */ |
371 | void __print_symbol(const char *fmt, unsigned long address) |
372 | { |
373 | char buffer[KSYM_SYMBOL_LEN]; |
374 | |
375 | sprint_symbol(buffer, address); |
376 | |
377 | printk(fmt, buffer); |
378 | } |
379 | EXPORT_SYMBOL(__print_symbol); |
380 | |
381 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ |
382 | struct kallsym_iter { |
383 | loff_t pos; |
384 | unsigned long value; |
385 | unsigned int nameoff; /* If iterating in core kernel symbols. */ |
386 | char type; |
387 | char name[KSYM_NAME_LEN]; |
388 | char module_name[MODULE_NAME_LEN]; |
389 | int exported; |
390 | }; |
391 | |
392 | static int get_ksymbol_mod(struct kallsym_iter *iter) |
393 | { |
394 | if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value, |
395 | &iter->type, iter->name, iter->module_name, |
396 | &iter->exported) < 0) |
397 | return 0; |
398 | return 1; |
399 | } |
400 | |
401 | /* Returns space to next name. */ |
402 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) |
403 | { |
404 | unsigned off = iter->nameoff; |
405 | |
406 | iter->module_name[0] = '\0'; |
407 | iter->value = kallsyms_addresses[iter->pos]; |
408 | |
409 | iter->type = kallsyms_get_symbol_type(off); |
410 | |
411 | off = kallsyms_expand_symbol(off, iter->name); |
412 | |
413 | return off - iter->nameoff; |
414 | } |
415 | |
416 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) |
417 | { |
418 | iter->name[0] = '\0'; |
419 | iter->nameoff = get_symbol_offset(new_pos); |
420 | iter->pos = new_pos; |
421 | } |
422 | |
423 | /* Returns false if pos at or past end of file. */ |
424 | static int update_iter(struct kallsym_iter *iter, loff_t pos) |
425 | { |
426 | /* Module symbols can be accessed randomly. */ |
427 | if (pos >= kallsyms_num_syms) { |
428 | iter->pos = pos; |
429 | return get_ksymbol_mod(iter); |
430 | } |
431 | |
432 | /* If we're not on the desired position, reset to new position. */ |
433 | if (pos != iter->pos) |
434 | reset_iter(iter, pos); |
435 | |
436 | iter->nameoff += get_ksymbol_core(iter); |
437 | iter->pos++; |
438 | |
439 | return 1; |
440 | } |
441 | |
442 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) |
443 | { |
444 | (*pos)++; |
445 | |
446 | if (!update_iter(m->private, *pos)) |
447 | return NULL; |
448 | return p; |
449 | } |
450 | |
451 | static void *s_start(struct seq_file *m, loff_t *pos) |
452 | { |
453 | if (!update_iter(m->private, *pos)) |
454 | return NULL; |
455 | return m->private; |
456 | } |
457 | |
458 | static void s_stop(struct seq_file *m, void *p) |
459 | { |
460 | } |
461 | |
462 | static int s_show(struct seq_file *m, void *p) |
463 | { |
464 | struct kallsym_iter *iter = m->private; |
465 | |
466 | /* Some debugging symbols have no name. Ignore them. */ |
467 | if (!iter->name[0]) |
468 | return 0; |
469 | |
470 | if (iter->module_name[0]) { |
471 | char type; |
472 | |
473 | /* |
474 | * Label it "global" if it is exported, |
475 | * "local" if not exported. |
476 | */ |
477 | type = iter->exported ? toupper(iter->type) : |
478 | tolower(iter->type); |
479 | seq_printf(m, "%0*lx %c %s\t[%s]\n", |
480 | (int)(2 * sizeof(void *)), |
481 | iter->value, type, iter->name, iter->module_name); |
482 | } else |
483 | seq_printf(m, "%0*lx %c %s\n", |
484 | (int)(2 * sizeof(void *)), |
485 | iter->value, iter->type, iter->name); |
486 | return 0; |
487 | } |
488 | |
489 | static const struct seq_operations kallsyms_op = { |
490 | .start = s_start, |
491 | .next = s_next, |
492 | .stop = s_stop, |
493 | .show = s_show |
494 | }; |
495 | |
496 | static int kallsyms_open(struct inode *inode, struct file *file) |
497 | { |
498 | /* |
499 | * We keep iterator in m->private, since normal case is to |
500 | * s_start from where we left off, so we avoid doing |
501 | * using get_symbol_offset for every symbol. |
502 | */ |
503 | struct kallsym_iter *iter; |
504 | int ret; |
505 | |
506 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); |
507 | if (!iter) |
508 | return -ENOMEM; |
509 | reset_iter(iter, 0); |
510 | |
511 | ret = seq_open(file, &kallsyms_op); |
512 | if (ret == 0) |
513 | ((struct seq_file *)file->private_data)->private = iter; |
514 | else |
515 | kfree(iter); |
516 | return ret; |
517 | } |
518 | |
519 | static const struct file_operations kallsyms_operations = { |
520 | .open = kallsyms_open, |
521 | .read = seq_read, |
522 | .llseek = seq_lseek, |
523 | .release = seq_release_private, |
524 | }; |
525 | |
526 | static int __init kallsyms_init(void) |
527 | { |
528 | proc_create("kallsyms", 0444, NULL, &kallsyms_operations); |
529 | return 0; |
530 | } |
531 | device_initcall(kallsyms_init); |
532 |
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