Ksplice: Add functions for walking kallsyms symbols
[linux-2.6.git] / kernel / kallsyms.c
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);