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 static unsigned long get_symbol_pos(unsigned long addr,
165 unsigned long *symbolsize,
166 unsigned long *offset)
167 {
168 unsigned long symbol_start = 0, symbol_end = 0;
169 unsigned long i, low, high, mid;
170
171 /* This kernel should never had been booted. */
172 BUG_ON(!kallsyms_addresses);
173
174 /* do a binary search on the sorted kallsyms_addresses array */
175 low = 0;
176 high = kallsyms_num_syms;
177
178 while (high - low > 1) {
179 mid = (low + high) / 2;
180 if (kallsyms_addresses[mid] <= addr)
181 low = mid;
182 else
183 high = mid;
184 }
185
186 /*
187 * search for the first aliased symbol. Aliased
188 * symbols are symbols with the same address
189 */
190 while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low])
191 --low;
192
193 symbol_start = kallsyms_addresses[low];
194
195 /* Search for next non-aliased symbol */
196 for (i = low + 1; i < kallsyms_num_syms; i++) {
197 if (kallsyms_addresses[i] > symbol_start) {
198 symbol_end = kallsyms_addresses[i];
199 break;
200 }
201 }
202
203 /* if we found no next symbol, we use the end of the section */
204 if (!symbol_end) {
205 if (is_kernel_inittext(addr))
206 symbol_end = (unsigned long)_einittext;
207 else if (all_var)
208 symbol_end = (unsigned long)_end;
209 else
210 symbol_end = (unsigned long)_etext;
211 }
212
213 if (symbolsize)
214 *symbolsize = symbol_end - symbol_start;
215 if (offset)
216 *offset = addr - symbol_start;
217
218 return low;
219 }
220
221 /*
222 * Lookup an address but don't bother to find any names.
223 */
224 int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
225 unsigned long *offset)
226 {
227 char namebuf[KSYM_NAME_LEN];
228 if (is_ksym_addr(addr))
229 return !!get_symbol_pos(addr, symbolsize, offset);
230
231 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
232 }
233
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 {
246 namebuf[KSYM_NAME_LEN - 1] = 0;
247 namebuf[0] = 0;
248
249 if (is_ksym_addr(addr)) {
250 unsigned long pos;
251
252 pos = get_symbol_pos(addr, symbolsize, offset);
253 /* Grab name */
254 kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);
255 if (modname)
256 *modname = NULL;
257 return namebuf;
258 }
259
260 /* see if it's in a module */
261 return module_address_lookup(addr, symbolsize, offset, modname,
262 namebuf);
263 return NULL;
264 }
265
266 int lookup_symbol_name(unsigned long addr, char *symname)
267 {
268 symname[0] = '\0';
269 symname[KSYM_NAME_LEN - 1] = '\0';
270
271 if (is_ksym_addr(addr)) {
272 unsigned long pos;
273
274 pos = get_symbol_pos(addr, NULL, NULL);
275 /* Grab name */
276 kallsyms_expand_symbol(get_symbol_offset(pos), symname);
277 return 0;
278 }
279 /* see if it's in a module */
280 return lookup_module_symbol_name(addr, symname);
281 }
282
283 int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
284 unsigned long *offset, char *modname, char *name)
285 {
286 name[0] = '\0';
287 name[KSYM_NAME_LEN - 1] = '\0';
288
289 if (is_ksym_addr(addr)) {
290 unsigned long pos;
291
292 pos = get_symbol_pos(addr, size, offset);
293 /* Grab name */
294 kallsyms_expand_symbol(get_symbol_offset(pos), name);
295 modname[0] = '\0';
296 return 0;
297 }
298 /* see if it's in a module */
299 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
300 }
301
302 /* Look up a kernel symbol and return it in a text buffer. */
303 int sprint_symbol(char *buffer, unsigned long address)
304 {
305 char *modname;
306 const char *name;
307 unsigned long offset, size;
308 char namebuf[KSYM_NAME_LEN];
309
310 name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);
311 if (!name)
312 return sprintf(buffer, "0x%lx", address);
313
314 if (modname)
315 return sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset,
316 size, modname);
317 else
318 return sprintf(buffer, "%s+%#lx/%#lx", name, offset, size);
319 }
320
321 /* Look up a kernel symbol and print it to the kernel messages. */
322 void __print_symbol(const char *fmt, unsigned long address)
323 {
324 char buffer[KSYM_SYMBOL_LEN];
325
326 sprint_symbol(buffer, address);
327
328 printk(fmt, buffer);
329 }
330
331 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
332 struct kallsym_iter
333 {
334 loff_t pos;
335 unsigned long value;
336 unsigned int nameoff; /* If iterating in core kernel symbols */
337 char type;
338 char name[KSYM_NAME_LEN];
339 char module_name[MODULE_NAME_LEN];
340 int exported;
341 };
342
343 static int get_ksymbol_mod(struct kallsym_iter *iter)
344 {
345 if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
346 &iter->type, iter->name, iter->module_name,
347 &iter->exported) < 0)
348 return 0;
349 return 1;
350 }
351
352 /* Returns space to next name. */
353 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
354 {
355 unsigned off = iter->nameoff;
356
357 iter->module_name[0] = '\0';
358 iter->value = kallsyms_addresses[iter->pos];
359
360 iter->type = kallsyms_get_symbol_type(off);
361
362 off = kallsyms_expand_symbol(off, iter->name);
363
364 return off - iter->nameoff;
365 }
366
367 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
368 {
369 iter->name[0] = '\0';
370 iter->nameoff = get_symbol_offset(new_pos);
371 iter->pos = new_pos;
372 }
373
374 /* Returns false if pos at or past end of file. */
375 static int update_iter(struct kallsym_iter *iter, loff_t pos)
376 {
377 /* Module symbols can be accessed randomly. */
378 if (pos >= kallsyms_num_syms) {
379 iter->pos = pos;
380 return get_ksymbol_mod(iter);
381 }
382
383 /* If we're not on the desired position, reset to new position. */
384 if (pos != iter->pos)
385 reset_iter(iter, pos);
386
387 iter->nameoff += get_ksymbol_core(iter);
388 iter->pos++;
389
390 return 1;
391 }
392
393 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
394 {
395 (*pos)++;
396
397 if (!update_iter(m->private, *pos))
398 return NULL;
399 return p;
400 }
401
402 static void *s_start(struct seq_file *m, loff_t *pos)
403 {
404 if (!update_iter(m->private, *pos))
405 return NULL;
406 return m->private;
407 }
408
409 static void s_stop(struct seq_file *m, void *p)
410 {
411 }
412
413 static int s_show(struct seq_file *m, void *p)
414 {
415 struct kallsym_iter *iter = m->private;
416
417 /* Some debugging symbols have no name. Ignore them. */
418 if (!iter->name[0])
419 return 0;
420
421 if (iter->module_name[0]) {
422 char type;
423
424 /* Label it "global" if it is exported,
425 * "local" if not exported. */
426 type = iter->exported ? toupper(iter->type) :
427 tolower(iter->type);
428 seq_printf(m, "%0*lx %c %s\t[%s]\n",
429 (int)(2*sizeof(void*)),
430 iter->value, type, iter->name, iter->module_name);
431 } else
432 seq_printf(m, "%0*lx %c %s\n",
433 (int)(2*sizeof(void*)),
434 iter->value, iter->type, iter->name);
435 return 0;
436 }
437
438 static const struct seq_operations kallsyms_op = {
439 .start = s_start,
440 .next = s_next,
441 .stop = s_stop,
442 .show = s_show
443 };
444
445 static int kallsyms_open(struct inode *inode, struct file *file)
446 {
447 /* We keep iterator in m->private, since normal case is to
448 * s_start from where we left off, so we avoid doing
449 * using get_symbol_offset for every symbol */
450 struct kallsym_iter *iter;
451 int ret;
452
453 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
454 if (!iter)
455 return -ENOMEM;
456 reset_iter(iter, 0);
457
458 ret = seq_open(file, &kallsyms_op);
459 if (ret == 0)
460 ((struct seq_file *)file->private_data)->private = iter;
461 else
462 kfree(iter);
463 return ret;
464 }
465
466 static const struct file_operations kallsyms_operations = {
467 .open = kallsyms_open,
468 .read = seq_read,
469 .llseek = seq_lseek,
470 .release = seq_release_private,
471 };
472
473 static int __init kallsyms_init(void)
474 {
475 struct proc_dir_entry *entry;
476
477 entry = create_proc_entry("kallsyms", 0444, NULL);
478 if (entry)
479 entry->proc_fops = &kallsyms_operations;
480 return 0;
481 }
482 __initcall(kallsyms_init);
483
484 EXPORT_SYMBOL(__print_symbol);
485 EXPORT_SYMBOL_GPL(sprint_symbol);
486
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