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1da177e4 LT |
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> | |
4e57b681 | 21 | #include <linux/sched.h> /* for cond_resched */ |
1da177e4 | 22 | #include <linux/mm.h> |
07354a00 | 23 | #include <linux/ctype.h> |
1da177e4 LT |
24 | |
25 | #include <asm/sections.h> | |
26 | ||
27 | #ifdef CONFIG_KALLSYMS_ALL | |
28 | #define all_var 1 | |
29 | #else | |
30 | #define all_var 0 | |
31 | #endif | |
32 | ||
33 | /* These will be re-linked against their real values during the second link stage */ | |
aad09470 JB |
34 | extern const unsigned long kallsyms_addresses[] __attribute__((weak)); |
35 | extern const unsigned long kallsyms_num_syms __attribute__((weak)); | |
36 | extern const u8 kallsyms_names[] __attribute__((weak)); | |
1da177e4 | 37 | |
aad09470 JB |
38 | extern const u8 kallsyms_token_table[] __attribute__((weak)); |
39 | extern const u16 kallsyms_token_index[] __attribute__((weak)); | |
1da177e4 | 40 | |
aad09470 | 41 | extern const unsigned long kallsyms_markers[] __attribute__((weak)); |
1da177e4 LT |
42 | |
43 | static inline int is_kernel_inittext(unsigned long addr) | |
44 | { | |
45 | if (addr >= (unsigned long)_sinittext | |
46 | && addr <= (unsigned long)_einittext) | |
47 | return 1; | |
48 | return 0; | |
49 | } | |
50 | ||
075d6eb1 DW |
51 | static inline int is_kernel_extratext(unsigned long addr) |
52 | { | |
53 | if (addr >= (unsigned long)_sextratext | |
54 | && addr <= (unsigned long)_eextratext) | |
55 | return 1; | |
56 | return 0; | |
57 | } | |
58 | ||
1da177e4 LT |
59 | static inline int is_kernel_text(unsigned long addr) |
60 | { | |
61 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) | |
62 | return 1; | |
63 | return in_gate_area_no_task(addr); | |
64 | } | |
65 | ||
66 | static inline int is_kernel(unsigned long addr) | |
67 | { | |
68 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) | |
69 | return 1; | |
70 | return in_gate_area_no_task(addr); | |
71 | } | |
72 | ||
ffc50891 FBH |
73 | static int is_ksym_addr(unsigned long addr) |
74 | { | |
75 | if (all_var) | |
76 | return is_kernel(addr); | |
77 | ||
78 | return is_kernel_text(addr) || is_kernel_inittext(addr) || | |
79 | is_kernel_extratext(addr); | |
80 | } | |
81 | ||
1da177e4 LT |
82 | /* expand a compressed symbol data into the resulting uncompressed string, |
83 | given the offset to where the symbol is in the compressed stream */ | |
84 | static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) | |
85 | { | |
86 | int len, skipped_first = 0; | |
aad09470 | 87 | const u8 *tptr, *data; |
1da177e4 LT |
88 | |
89 | /* get the compressed symbol length from the first symbol byte */ | |
90 | data = &kallsyms_names[off]; | |
91 | len = *data; | |
92 | data++; | |
93 | ||
94 | /* update the offset to return the offset for the next symbol on | |
95 | * the compressed stream */ | |
96 | off += len + 1; | |
97 | ||
98 | /* for every byte on the compressed symbol data, copy the table | |
99 | entry for that byte */ | |
100 | while(len) { | |
101 | tptr = &kallsyms_token_table[ kallsyms_token_index[*data] ]; | |
102 | data++; | |
103 | len--; | |
104 | ||
105 | while (*tptr) { | |
106 | if(skipped_first) { | |
107 | *result = *tptr; | |
108 | result++; | |
109 | } else | |
110 | skipped_first = 1; | |
111 | tptr++; | |
112 | } | |
113 | } | |
114 | ||
115 | *result = '\0'; | |
116 | ||
117 | /* return to offset to the next symbol */ | |
118 | return off; | |
119 | } | |
120 | ||
121 | /* get symbol type information. This is encoded as a single char at the | |
122 | * begining of the symbol name */ | |
123 | static char kallsyms_get_symbol_type(unsigned int off) | |
124 | { | |
125 | /* get just the first code, look it up in the token table, and return the | |
126 | * first char from this token */ | |
127 | return kallsyms_token_table[ kallsyms_token_index[ kallsyms_names[off+1] ] ]; | |
128 | } | |
129 | ||
130 | ||
131 | /* find the offset on the compressed stream given and index in the | |
132 | * kallsyms array */ | |
133 | static unsigned int get_symbol_offset(unsigned long pos) | |
134 | { | |
aad09470 | 135 | const u8 *name; |
1da177e4 LT |
136 | int i; |
137 | ||
138 | /* use the closest marker we have. We have markers every 256 positions, | |
139 | * so that should be close enough */ | |
140 | name = &kallsyms_names[ kallsyms_markers[pos>>8] ]; | |
141 | ||
142 | /* sequentially scan all the symbols up to the point we're searching for. | |
143 | * Every symbol is stored in a [<len>][<len> bytes of data] format, so we | |
144 | * just need to add the len to the current pointer for every symbol we | |
145 | * wish to skip */ | |
146 | for(i = 0; i < (pos&0xFF); i++) | |
147 | name = name + (*name) + 1; | |
148 | ||
149 | return name - kallsyms_names; | |
150 | } | |
151 | ||
152 | /* Lookup the address for this symbol. Returns 0 if not found. */ | |
153 | unsigned long kallsyms_lookup_name(const char *name) | |
154 | { | |
155 | char namebuf[KSYM_NAME_LEN+1]; | |
156 | unsigned long i; | |
157 | unsigned int off; | |
158 | ||
159 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
160 | off = kallsyms_expand_symbol(off, namebuf); | |
161 | ||
162 | if (strcmp(namebuf, name) == 0) | |
163 | return kallsyms_addresses[i]; | |
164 | } | |
165 | return module_kallsyms_lookup_name(name); | |
166 | } | |
1da177e4 | 167 | |
ffc50891 FBH |
168 | static unsigned long get_symbol_pos(unsigned long addr, |
169 | unsigned long *symbolsize, | |
170 | unsigned long *offset) | |
171 | { | |
172 | unsigned long symbol_start = 0, symbol_end = 0; | |
173 | unsigned long i, low, high, mid; | |
174 | ||
175 | /* This kernel should never had been booted. */ | |
176 | BUG_ON(!kallsyms_addresses); | |
177 | ||
178 | /* do a binary search on the sorted kallsyms_addresses array */ | |
179 | low = 0; | |
180 | high = kallsyms_num_syms; | |
181 | ||
182 | while (high - low > 1) { | |
183 | mid = (low + high) / 2; | |
184 | if (kallsyms_addresses[mid] <= addr) | |
185 | low = mid; | |
186 | else | |
187 | high = mid; | |
188 | } | |
189 | ||
190 | /* | |
191 | * search for the first aliased symbol. Aliased | |
192 | * symbols are symbols with the same address | |
193 | */ | |
194 | while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low]) | |
195 | --low; | |
196 | ||
197 | symbol_start = kallsyms_addresses[low]; | |
198 | ||
199 | /* Search for next non-aliased symbol */ | |
200 | for (i = low + 1; i < kallsyms_num_syms; i++) { | |
201 | if (kallsyms_addresses[i] > symbol_start) { | |
202 | symbol_end = kallsyms_addresses[i]; | |
203 | break; | |
204 | } | |
205 | } | |
206 | ||
207 | /* if we found no next symbol, we use the end of the section */ | |
208 | if (!symbol_end) { | |
209 | if (is_kernel_inittext(addr)) | |
210 | symbol_end = (unsigned long)_einittext; | |
211 | else if (all_var) | |
212 | symbol_end = (unsigned long)_end; | |
213 | else | |
214 | symbol_end = (unsigned long)_etext; | |
215 | } | |
216 | ||
ffb45122 AD |
217 | if (symbolsize) |
218 | *symbolsize = symbol_end - symbol_start; | |
219 | if (offset) | |
220 | *offset = addr - symbol_start; | |
ffc50891 FBH |
221 | |
222 | return low; | |
223 | } | |
224 | ||
225 | /* | |
226 | * Lookup an address but don't bother to find any names. | |
227 | */ | |
228 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, | |
229 | unsigned long *offset) | |
230 | { | |
231 | if (is_ksym_addr(addr)) | |
232 | return !!get_symbol_pos(addr, symbolsize, offset); | |
233 | ||
234 | return !!module_address_lookup(addr, symbolsize, offset, NULL); | |
235 | } | |
236 | ||
1da177e4 LT |
237 | /* |
238 | * Lookup an address | |
239 | * - modname is set to NULL if it's in the kernel | |
240 | * - we guarantee that the returned name is valid until we reschedule even if | |
241 | * it resides in a module | |
242 | * - we also guarantee that modname will be valid until rescheduled | |
243 | */ | |
244 | const char *kallsyms_lookup(unsigned long addr, | |
245 | unsigned long *symbolsize, | |
246 | unsigned long *offset, | |
247 | char **modname, char *namebuf) | |
248 | { | |
1da177e4 LT |
249 | const char *msym; |
250 | ||
1da177e4 LT |
251 | namebuf[KSYM_NAME_LEN] = 0; |
252 | namebuf[0] = 0; | |
253 | ||
ffc50891 FBH |
254 | if (is_ksym_addr(addr)) { |
255 | unsigned long pos; | |
1da177e4 | 256 | |
ffc50891 | 257 | pos = get_symbol_pos(addr, symbolsize, offset); |
1da177e4 | 258 | /* Grab name */ |
ffc50891 | 259 | kallsyms_expand_symbol(get_symbol_offset(pos), namebuf); |
1da177e4 | 260 | *modname = NULL; |
1da177e4 LT |
261 | return namebuf; |
262 | } | |
263 | ||
264 | /* see if it's in a module */ | |
265 | msym = module_address_lookup(addr, symbolsize, offset, modname); | |
266 | if (msym) | |
267 | return strncpy(namebuf, msym, KSYM_NAME_LEN); | |
268 | ||
269 | return NULL; | |
270 | } | |
271 | ||
9d65cb4a AD |
272 | int lookup_symbol_name(unsigned long addr, char *symname) |
273 | { | |
274 | symname[0] = '\0'; | |
275 | symname[KSYM_NAME_LEN] = '\0'; | |
276 | ||
277 | if (is_ksym_addr(addr)) { | |
278 | unsigned long pos; | |
279 | ||
280 | pos = get_symbol_pos(addr, NULL, NULL); | |
281 | /* Grab name */ | |
282 | kallsyms_expand_symbol(get_symbol_offset(pos), symname); | |
283 | return 0; | |
284 | } | |
285 | /* see if it's in a module */ | |
286 | return lookup_module_symbol_name(addr, symname); | |
287 | } | |
288 | ||
42e38083 RP |
289 | /* Look up a kernel symbol and return it in a text buffer. */ |
290 | int sprint_symbol(char *buffer, unsigned long address) | |
1da177e4 LT |
291 | { |
292 | char *modname; | |
293 | const char *name; | |
294 | unsigned long offset, size; | |
295 | char namebuf[KSYM_NAME_LEN+1]; | |
1da177e4 LT |
296 | |
297 | name = kallsyms_lookup(address, &size, &offset, &modname, namebuf); | |
1da177e4 | 298 | if (!name) |
42e38083 | 299 | return sprintf(buffer, "0x%lx", address); |
1da177e4 LT |
300 | else { |
301 | if (modname) | |
42e38083 | 302 | return sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset, |
1da177e4 LT |
303 | size, modname); |
304 | else | |
42e38083 | 305 | return sprintf(buffer, "%s+%#lx/%#lx", name, offset, size); |
1da177e4 | 306 | } |
42e38083 RP |
307 | } |
308 | ||
309 | /* Look up a kernel symbol and print it to the kernel messages. */ | |
310 | void __print_symbol(const char *fmt, unsigned long address) | |
311 | { | |
312 | char buffer[KSYM_SYMBOL_LEN]; | |
313 | ||
314 | sprint_symbol(buffer, address); | |
315 | ||
1da177e4 LT |
316 | printk(fmt, buffer); |
317 | } | |
318 | ||
319 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ | |
320 | struct kallsym_iter | |
321 | { | |
322 | loff_t pos; | |
1da177e4 LT |
323 | unsigned long value; |
324 | unsigned int nameoff; /* If iterating in core kernel symbols */ | |
325 | char type; | |
326 | char name[KSYM_NAME_LEN+1]; | |
ea07890a AD |
327 | char module_name[MODULE_NAME_LEN + 1]; |
328 | int exported; | |
1da177e4 LT |
329 | }; |
330 | ||
1da177e4 LT |
331 | static int get_ksymbol_mod(struct kallsym_iter *iter) |
332 | { | |
ea07890a AD |
333 | if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value, |
334 | &iter->type, iter->name, iter->module_name, | |
335 | &iter->exported) < 0) | |
1da177e4 | 336 | return 0; |
1da177e4 LT |
337 | return 1; |
338 | } | |
339 | ||
340 | /* Returns space to next name. */ | |
341 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
342 | { | |
343 | unsigned off = iter->nameoff; | |
344 | ||
ea07890a | 345 | iter->module_name[0] = '\0'; |
1da177e4 LT |
346 | iter->value = kallsyms_addresses[iter->pos]; |
347 | ||
348 | iter->type = kallsyms_get_symbol_type(off); | |
349 | ||
350 | off = kallsyms_expand_symbol(off, iter->name); | |
351 | ||
352 | return off - iter->nameoff; | |
353 | } | |
354 | ||
355 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
356 | { | |
357 | iter->name[0] = '\0'; | |
358 | iter->nameoff = get_symbol_offset(new_pos); | |
359 | iter->pos = new_pos; | |
360 | } | |
361 | ||
362 | /* Returns false if pos at or past end of file. */ | |
363 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
364 | { | |
365 | /* Module symbols can be accessed randomly. */ | |
366 | if (pos >= kallsyms_num_syms) { | |
367 | iter->pos = pos; | |
368 | return get_ksymbol_mod(iter); | |
369 | } | |
370 | ||
371 | /* If we're not on the desired position, reset to new position. */ | |
372 | if (pos != iter->pos) | |
373 | reset_iter(iter, pos); | |
374 | ||
375 | iter->nameoff += get_ksymbol_core(iter); | |
376 | iter->pos++; | |
377 | ||
378 | return 1; | |
379 | } | |
380 | ||
381 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
382 | { | |
383 | (*pos)++; | |
384 | ||
385 | if (!update_iter(m->private, *pos)) | |
386 | return NULL; | |
387 | return p; | |
388 | } | |
389 | ||
390 | static void *s_start(struct seq_file *m, loff_t *pos) | |
391 | { | |
392 | if (!update_iter(m->private, *pos)) | |
393 | return NULL; | |
394 | return m->private; | |
395 | } | |
396 | ||
397 | static void s_stop(struct seq_file *m, void *p) | |
398 | { | |
399 | } | |
400 | ||
401 | static int s_show(struct seq_file *m, void *p) | |
402 | { | |
403 | struct kallsym_iter *iter = m->private; | |
404 | ||
405 | /* Some debugging symbols have no name. Ignore them. */ | |
406 | if (!iter->name[0]) | |
407 | return 0; | |
408 | ||
ea07890a AD |
409 | if (iter->module_name[0]) { |
410 | char type; | |
411 | ||
412 | /* Label it "global" if it is exported, | |
413 | * "local" if not exported. */ | |
414 | type = iter->exported ? toupper(iter->type) : | |
415 | tolower(iter->type); | |
1da177e4 LT |
416 | seq_printf(m, "%0*lx %c %s\t[%s]\n", |
417 | (int)(2*sizeof(void*)), | |
ea07890a AD |
418 | iter->value, type, iter->name, iter->module_name); |
419 | } else | |
1da177e4 LT |
420 | seq_printf(m, "%0*lx %c %s\n", |
421 | (int)(2*sizeof(void*)), | |
422 | iter->value, iter->type, iter->name); | |
423 | return 0; | |
424 | } | |
425 | ||
15ad7cdc | 426 | static const struct seq_operations kallsyms_op = { |
1da177e4 LT |
427 | .start = s_start, |
428 | .next = s_next, | |
429 | .stop = s_stop, | |
430 | .show = s_show | |
431 | }; | |
432 | ||
433 | static int kallsyms_open(struct inode *inode, struct file *file) | |
434 | { | |
435 | /* We keep iterator in m->private, since normal case is to | |
436 | * s_start from where we left off, so we avoid doing | |
437 | * using get_symbol_offset for every symbol */ | |
438 | struct kallsym_iter *iter; | |
439 | int ret; | |
440 | ||
441 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
442 | if (!iter) | |
443 | return -ENOMEM; | |
444 | reset_iter(iter, 0); | |
445 | ||
446 | ret = seq_open(file, &kallsyms_op); | |
447 | if (ret == 0) | |
448 | ((struct seq_file *)file->private_data)->private = iter; | |
449 | else | |
450 | kfree(iter); | |
451 | return ret; | |
452 | } | |
453 | ||
454 | static int kallsyms_release(struct inode *inode, struct file *file) | |
455 | { | |
456 | struct seq_file *m = (struct seq_file *)file->private_data; | |
457 | kfree(m->private); | |
458 | return seq_release(inode, file); | |
459 | } | |
460 | ||
15ad7cdc | 461 | static const struct file_operations kallsyms_operations = { |
1da177e4 LT |
462 | .open = kallsyms_open, |
463 | .read = seq_read, | |
464 | .llseek = seq_lseek, | |
465 | .release = kallsyms_release, | |
466 | }; | |
467 | ||
468 | static int __init kallsyms_init(void) | |
469 | { | |
470 | struct proc_dir_entry *entry; | |
471 | ||
472 | entry = create_proc_entry("kallsyms", 0444, NULL); | |
473 | if (entry) | |
474 | entry->proc_fops = &kallsyms_operations; | |
475 | return 0; | |
476 | } | |
477 | __initcall(kallsyms_init); | |
478 | ||
479 | EXPORT_SYMBOL(__print_symbol); | |
42e38083 | 480 | EXPORT_SYMBOL_GPL(sprint_symbol); |