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