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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 LT |
22 | #include <linux/mm.h> |
23 | ||
24 | #include <asm/sections.h> | |
25 | ||
26 | #ifdef CONFIG_KALLSYMS_ALL | |
27 | #define all_var 1 | |
28 | #else | |
29 | #define all_var 0 | |
30 | #endif | |
31 | ||
32 | /* These will be re-linked against their real values during the second link stage */ | |
33 | extern unsigned long kallsyms_addresses[] __attribute__((weak)); | |
34 | extern unsigned long kallsyms_num_syms __attribute__((weak,section("data"))); | |
35 | extern u8 kallsyms_names[] __attribute__((weak)); | |
36 | ||
37 | extern u8 kallsyms_token_table[] __attribute__((weak)); | |
38 | extern u16 kallsyms_token_index[] __attribute__((weak)); | |
39 | ||
40 | extern unsigned long kallsyms_markers[] __attribute__((weak)); | |
41 | ||
42 | static inline int is_kernel_inittext(unsigned long addr) | |
43 | { | |
44 | if (addr >= (unsigned long)_sinittext | |
45 | && addr <= (unsigned long)_einittext) | |
46 | return 1; | |
47 | return 0; | |
48 | } | |
49 | ||
075d6eb1 DW |
50 | static inline int is_kernel_extratext(unsigned long addr) |
51 | { | |
52 | if (addr >= (unsigned long)_sextratext | |
53 | && addr <= (unsigned long)_eextratext) | |
54 | return 1; | |
55 | return 0; | |
56 | } | |
57 | ||
1da177e4 LT |
58 | static inline int is_kernel_text(unsigned long addr) |
59 | { | |
60 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) | |
61 | return 1; | |
62 | return in_gate_area_no_task(addr); | |
63 | } | |
64 | ||
65 | static inline int is_kernel(unsigned long addr) | |
66 | { | |
67 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) | |
68 | return 1; | |
69 | return in_gate_area_no_task(addr); | |
70 | } | |
71 | ||
ffc50891 FBH |
72 | static int is_ksym_addr(unsigned long addr) |
73 | { | |
74 | if (all_var) | |
75 | return is_kernel(addr); | |
76 | ||
77 | return is_kernel_text(addr) || is_kernel_inittext(addr) || | |
78 | is_kernel_extratext(addr); | |
79 | } | |
80 | ||
1da177e4 LT |
81 | /* expand a compressed symbol data into the resulting uncompressed string, |
82 | given the offset to where the symbol is in the compressed stream */ | |
83 | static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) | |
84 | { | |
85 | int len, skipped_first = 0; | |
86 | u8 *tptr, *data; | |
87 | ||
88 | /* get the compressed symbol length from the first symbol byte */ | |
89 | data = &kallsyms_names[off]; | |
90 | len = *data; | |
91 | data++; | |
92 | ||
93 | /* update the offset to return the offset for the next symbol on | |
94 | * the compressed stream */ | |
95 | off += len + 1; | |
96 | ||
97 | /* for every byte on the compressed symbol data, copy the table | |
98 | entry for that byte */ | |
99 | while(len) { | |
100 | tptr = &kallsyms_token_table[ kallsyms_token_index[*data] ]; | |
101 | data++; | |
102 | len--; | |
103 | ||
104 | while (*tptr) { | |
105 | if(skipped_first) { | |
106 | *result = *tptr; | |
107 | result++; | |
108 | } else | |
109 | skipped_first = 1; | |
110 | tptr++; | |
111 | } | |
112 | } | |
113 | ||
114 | *result = '\0'; | |
115 | ||
116 | /* return to offset to the next symbol */ | |
117 | return off; | |
118 | } | |
119 | ||
120 | /* get symbol type information. This is encoded as a single char at the | |
121 | * begining of the symbol name */ | |
122 | static char kallsyms_get_symbol_type(unsigned int off) | |
123 | { | |
124 | /* get just the first code, look it up in the token table, and return the | |
125 | * first char from this token */ | |
126 | return kallsyms_token_table[ kallsyms_token_index[ kallsyms_names[off+1] ] ]; | |
127 | } | |
128 | ||
129 | ||
130 | /* find the offset on the compressed stream given and index in the | |
131 | * kallsyms array */ | |
132 | static unsigned int get_symbol_offset(unsigned long pos) | |
133 | { | |
134 | u8 *name; | |
135 | int i; | |
136 | ||
137 | /* use the closest marker we have. We have markers every 256 positions, | |
138 | * so that should be close enough */ | |
139 | name = &kallsyms_names[ kallsyms_markers[pos>>8] ]; | |
140 | ||
141 | /* sequentially scan all the symbols up to the point we're searching for. | |
142 | * Every symbol is stored in a [<len>][<len> bytes of data] format, so we | |
143 | * just need to add the len to the current pointer for every symbol we | |
144 | * wish to skip */ | |
145 | for(i = 0; i < (pos&0xFF); i++) | |
146 | name = name + (*name) + 1; | |
147 | ||
148 | return name - kallsyms_names; | |
149 | } | |
150 | ||
151 | /* Lookup the address for this symbol. Returns 0 if not found. */ | |
152 | unsigned long kallsyms_lookup_name(const char *name) | |
153 | { | |
154 | char namebuf[KSYM_NAME_LEN+1]; | |
155 | unsigned long i; | |
156 | unsigned int off; | |
157 | ||
158 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
159 | off = kallsyms_expand_symbol(off, namebuf); | |
160 | ||
161 | if (strcmp(namebuf, name) == 0) | |
162 | return kallsyms_addresses[i]; | |
163 | } | |
164 | return module_kallsyms_lookup_name(name); | |
165 | } | |
1da177e4 | 166 | |
ffc50891 FBH |
167 | static unsigned long get_symbol_pos(unsigned long addr, |
168 | unsigned long *symbolsize, | |
169 | unsigned long *offset) | |
170 | { | |
171 | unsigned long symbol_start = 0, symbol_end = 0; | |
172 | unsigned long i, low, high, mid; | |
173 | ||
174 | /* This kernel should never had been booted. */ | |
175 | BUG_ON(!kallsyms_addresses); | |
176 | ||
177 | /* do a binary search on the sorted kallsyms_addresses array */ | |
178 | low = 0; | |
179 | high = kallsyms_num_syms; | |
180 | ||
181 | while (high - low > 1) { | |
182 | mid = (low + high) / 2; | |
183 | if (kallsyms_addresses[mid] <= addr) | |
184 | low = mid; | |
185 | else | |
186 | high = mid; | |
187 | } | |
188 | ||
189 | /* | |
190 | * search for the first aliased symbol. Aliased | |
191 | * symbols are symbols with the same address | |
192 | */ | |
193 | while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low]) | |
194 | --low; | |
195 | ||
196 | symbol_start = kallsyms_addresses[low]; | |
197 | ||
198 | /* Search for next non-aliased symbol */ | |
199 | for (i = low + 1; i < kallsyms_num_syms; i++) { | |
200 | if (kallsyms_addresses[i] > symbol_start) { | |
201 | symbol_end = kallsyms_addresses[i]; | |
202 | break; | |
203 | } | |
204 | } | |
205 | ||
206 | /* if we found no next symbol, we use the end of the section */ | |
207 | if (!symbol_end) { | |
208 | if (is_kernel_inittext(addr)) | |
209 | symbol_end = (unsigned long)_einittext; | |
210 | else if (all_var) | |
211 | symbol_end = (unsigned long)_end; | |
212 | else | |
213 | symbol_end = (unsigned long)_etext; | |
214 | } | |
215 | ||
216 | *symbolsize = symbol_end - symbol_start; | |
217 | *offset = addr - symbol_start; | |
218 | ||
219 | return low; | |
220 | } | |
221 | ||
222 | /* | |
223 | * Lookup an address but don't bother to find any names. | |
224 | */ | |
225 | int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, | |
226 | unsigned long *offset) | |
227 | { | |
228 | if (is_ksym_addr(addr)) | |
229 | return !!get_symbol_pos(addr, symbolsize, offset); | |
230 | ||
231 | return !!module_address_lookup(addr, symbolsize, offset, NULL); | |
232 | } | |
233 | ||
1da177e4 LT |
234 | /* |
235 | * Lookup an address | |
236 | * - modname is set to NULL if it's in the kernel | |
237 | * - we guarantee that the returned name is valid until we reschedule even if | |
238 | * it resides in a module | |
239 | * - we also guarantee that modname will be valid until rescheduled | |
240 | */ | |
241 | const char *kallsyms_lookup(unsigned long addr, | |
242 | unsigned long *symbolsize, | |
243 | unsigned long *offset, | |
244 | char **modname, char *namebuf) | |
245 | { | |
1da177e4 LT |
246 | const char *msym; |
247 | ||
1da177e4 LT |
248 | namebuf[KSYM_NAME_LEN] = 0; |
249 | namebuf[0] = 0; | |
250 | ||
ffc50891 FBH |
251 | if (is_ksym_addr(addr)) { |
252 | unsigned long pos; | |
1da177e4 | 253 | |
ffc50891 | 254 | pos = get_symbol_pos(addr, symbolsize, offset); |
1da177e4 | 255 | /* Grab name */ |
ffc50891 | 256 | kallsyms_expand_symbol(get_symbol_offset(pos), namebuf); |
1da177e4 | 257 | *modname = NULL; |
1da177e4 LT |
258 | return namebuf; |
259 | } | |
260 | ||
261 | /* see if it's in a module */ | |
262 | msym = module_address_lookup(addr, symbolsize, offset, modname); | |
263 | if (msym) | |
264 | return strncpy(namebuf, msym, KSYM_NAME_LEN); | |
265 | ||
266 | return NULL; | |
267 | } | |
268 | ||
269 | /* Replace "%s" in format with address, or returns -errno. */ | |
270 | void __print_symbol(const char *fmt, unsigned long address) | |
271 | { | |
272 | char *modname; | |
273 | const char *name; | |
274 | unsigned long offset, size; | |
275 | char namebuf[KSYM_NAME_LEN+1]; | |
276 | char buffer[sizeof("%s+%#lx/%#lx [%s]") + KSYM_NAME_LEN + | |
277 | 2*(BITS_PER_LONG*3/10) + MODULE_NAME_LEN + 1]; | |
278 | ||
279 | name = kallsyms_lookup(address, &size, &offset, &modname, namebuf); | |
280 | ||
281 | if (!name) | |
282 | sprintf(buffer, "0x%lx", address); | |
283 | else { | |
284 | if (modname) | |
285 | sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset, | |
286 | size, modname); | |
287 | else | |
288 | sprintf(buffer, "%s+%#lx/%#lx", name, offset, size); | |
289 | } | |
290 | printk(fmt, buffer); | |
291 | } | |
292 | ||
293 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ | |
294 | struct kallsym_iter | |
295 | { | |
296 | loff_t pos; | |
297 | struct module *owner; | |
298 | unsigned long value; | |
299 | unsigned int nameoff; /* If iterating in core kernel symbols */ | |
300 | char type; | |
301 | char name[KSYM_NAME_LEN+1]; | |
302 | }; | |
303 | ||
304 | /* Only label it "global" if it is exported. */ | |
305 | static void upcase_if_global(struct kallsym_iter *iter) | |
306 | { | |
307 | if (is_exported(iter->name, iter->owner)) | |
308 | iter->type += 'A' - 'a'; | |
309 | } | |
310 | ||
311 | static int get_ksymbol_mod(struct kallsym_iter *iter) | |
312 | { | |
313 | iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms, | |
098c5eea AG |
314 | &iter->value, &iter->type, |
315 | iter->name, sizeof(iter->name)); | |
1da177e4 LT |
316 | if (iter->owner == NULL) |
317 | return 0; | |
318 | ||
319 | upcase_if_global(iter); | |
320 | return 1; | |
321 | } | |
322 | ||
323 | /* Returns space to next name. */ | |
324 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
325 | { | |
326 | unsigned off = iter->nameoff; | |
327 | ||
328 | iter->owner = NULL; | |
329 | iter->value = kallsyms_addresses[iter->pos]; | |
330 | ||
331 | iter->type = kallsyms_get_symbol_type(off); | |
332 | ||
333 | off = kallsyms_expand_symbol(off, iter->name); | |
334 | ||
335 | return off - iter->nameoff; | |
336 | } | |
337 | ||
338 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
339 | { | |
340 | iter->name[0] = '\0'; | |
341 | iter->nameoff = get_symbol_offset(new_pos); | |
342 | iter->pos = new_pos; | |
343 | } | |
344 | ||
345 | /* Returns false if pos at or past end of file. */ | |
346 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
347 | { | |
348 | /* Module symbols can be accessed randomly. */ | |
349 | if (pos >= kallsyms_num_syms) { | |
350 | iter->pos = pos; | |
351 | return get_ksymbol_mod(iter); | |
352 | } | |
353 | ||
354 | /* If we're not on the desired position, reset to new position. */ | |
355 | if (pos != iter->pos) | |
356 | reset_iter(iter, pos); | |
357 | ||
358 | iter->nameoff += get_ksymbol_core(iter); | |
359 | iter->pos++; | |
360 | ||
361 | return 1; | |
362 | } | |
363 | ||
364 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
365 | { | |
366 | (*pos)++; | |
367 | ||
368 | if (!update_iter(m->private, *pos)) | |
369 | return NULL; | |
370 | return p; | |
371 | } | |
372 | ||
373 | static void *s_start(struct seq_file *m, loff_t *pos) | |
374 | { | |
375 | if (!update_iter(m->private, *pos)) | |
376 | return NULL; | |
377 | return m->private; | |
378 | } | |
379 | ||
380 | static void s_stop(struct seq_file *m, void *p) | |
381 | { | |
382 | } | |
383 | ||
384 | static int s_show(struct seq_file *m, void *p) | |
385 | { | |
386 | struct kallsym_iter *iter = m->private; | |
387 | ||
388 | /* Some debugging symbols have no name. Ignore them. */ | |
389 | if (!iter->name[0]) | |
390 | return 0; | |
391 | ||
392 | if (iter->owner) | |
393 | seq_printf(m, "%0*lx %c %s\t[%s]\n", | |
394 | (int)(2*sizeof(void*)), | |
395 | iter->value, iter->type, iter->name, | |
396 | module_name(iter->owner)); | |
397 | else | |
398 | seq_printf(m, "%0*lx %c %s\n", | |
399 | (int)(2*sizeof(void*)), | |
400 | iter->value, iter->type, iter->name); | |
401 | return 0; | |
402 | } | |
403 | ||
404 | static struct seq_operations kallsyms_op = { | |
405 | .start = s_start, | |
406 | .next = s_next, | |
407 | .stop = s_stop, | |
408 | .show = s_show | |
409 | }; | |
410 | ||
411 | static int kallsyms_open(struct inode *inode, struct file *file) | |
412 | { | |
413 | /* We keep iterator in m->private, since normal case is to | |
414 | * s_start from where we left off, so we avoid doing | |
415 | * using get_symbol_offset for every symbol */ | |
416 | struct kallsym_iter *iter; | |
417 | int ret; | |
418 | ||
419 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
420 | if (!iter) | |
421 | return -ENOMEM; | |
422 | reset_iter(iter, 0); | |
423 | ||
424 | ret = seq_open(file, &kallsyms_op); | |
425 | if (ret == 0) | |
426 | ((struct seq_file *)file->private_data)->private = iter; | |
427 | else | |
428 | kfree(iter); | |
429 | return ret; | |
430 | } | |
431 | ||
432 | static int kallsyms_release(struct inode *inode, struct file *file) | |
433 | { | |
434 | struct seq_file *m = (struct seq_file *)file->private_data; | |
435 | kfree(m->private); | |
436 | return seq_release(inode, file); | |
437 | } | |
438 | ||
439 | static struct file_operations kallsyms_operations = { | |
440 | .open = kallsyms_open, | |
441 | .read = seq_read, | |
442 | .llseek = seq_lseek, | |
443 | .release = kallsyms_release, | |
444 | }; | |
445 | ||
446 | static int __init kallsyms_init(void) | |
447 | { | |
448 | struct proc_dir_entry *entry; | |
449 | ||
450 | entry = create_proc_entry("kallsyms", 0444, NULL); | |
451 | if (entry) | |
452 | entry->proc_fops = &kallsyms_operations; | |
453 | return 0; | |
454 | } | |
455 | __initcall(kallsyms_init); | |
456 | ||
457 | EXPORT_SYMBOL(__print_symbol); |