kallsyms: make KSYM_NAME_LEN include space for trailing '\0'
[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 unsigned long kallsyms_num_syms __attribute__((weak));
36 extern const u8 kallsyms_names[] __attribute__((weak));
37
38 extern const u8 kallsyms_token_table[] __attribute__((weak));
39 extern const u16 kallsyms_token_index[] __attribute__((weak));
40
41 extern const unsigned long kallsyms_markers[] __attribute__((weak));
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
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
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
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
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;
87         const u8 *tptr, *data;
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 {
135         const u8 *name;
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];
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 }
167
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
217         if (symbolsize)
218                 *symbolsize = symbol_end - symbol_start;
219         if (offset)
220                 *offset = addr - symbol_start;
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
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 {
249         const char *msym;
250
251         namebuf[KSYM_NAME_LEN - 1] = 0;
252         namebuf[0] = 0;
253
254         if (is_ksym_addr(addr)) {
255                 unsigned long pos;
256
257                 pos = get_symbol_pos(addr, symbolsize, offset);
258                 /* Grab name */
259                 kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);
260                 if (modname)
261                         *modname = NULL;
262                 return namebuf;
263         }
264
265         /* see if it's in a module */
266         msym = module_address_lookup(addr, symbolsize, offset, modname);
267         if (msym)
268                 return strncpy(namebuf, msym, KSYM_NAME_LEN - 1);
269
270         return NULL;
271 }
272
273 int lookup_symbol_name(unsigned long addr, char *symname)
274 {
275         symname[0] = '\0';
276         symname[KSYM_NAME_LEN - 1] = '\0';
277
278         if (is_ksym_addr(addr)) {
279                 unsigned long pos;
280
281                 pos = get_symbol_pos(addr, NULL, NULL);
282                 /* Grab name */
283                 kallsyms_expand_symbol(get_symbol_offset(pos), symname);
284                 return 0;
285         }
286         /* see if it's in a module */
287         return lookup_module_symbol_name(addr, symname);
288 }
289
290 int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
291                         unsigned long *offset, char *modname, char *name)
292 {
293         name[0] = '\0';
294         name[KSYM_NAME_LEN - 1] = '\0';
295
296         if (is_ksym_addr(addr)) {
297                 unsigned long pos;
298
299                 pos = get_symbol_pos(addr, size, offset);
300                 /* Grab name */
301                 kallsyms_expand_symbol(get_symbol_offset(pos), name);
302                 modname[0] = '\0';
303                 return 0;
304         }
305         /* see if it's in a module */
306         return lookup_module_symbol_attrs(addr, size, offset, modname, name);
307 }
308
309 /* Look up a kernel symbol and return it in a text buffer. */
310 int sprint_symbol(char *buffer, unsigned long address)
311 {
312         char *modname;
313         const char *name;
314         unsigned long offset, size;
315         char namebuf[KSYM_NAME_LEN];
316
317         name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);
318         if (!name)
319                 return sprintf(buffer, "0x%lx", address);
320
321         if (modname)
322                 return sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset,
323                                 size, modname);
324         else
325                 return sprintf(buffer, "%s+%#lx/%#lx", name, offset, size);
326 }
327
328 /* Look up a kernel symbol and print it to the kernel messages. */
329 void __print_symbol(const char *fmt, unsigned long address)
330 {
331         char buffer[KSYM_SYMBOL_LEN];
332
333         sprint_symbol(buffer, address);
334
335         printk(fmt, buffer);
336 }
337
338 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
339 struct kallsym_iter
340 {
341         loff_t pos;
342         unsigned long value;
343         unsigned int nameoff; /* If iterating in core kernel symbols */
344         char type;
345         char name[KSYM_NAME_LEN];
346         char module_name[MODULE_NAME_LEN];
347         int exported;
348 };
349
350 static int get_ksymbol_mod(struct kallsym_iter *iter)
351 {
352         if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
353                                 &iter->type, iter->name, iter->module_name,
354                                 &iter->exported) < 0)
355                 return 0;
356         return 1;
357 }
358
359 /* Returns space to next name. */
360 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
361 {
362         unsigned off = iter->nameoff;
363
364         iter->module_name[0] = '\0';
365         iter->value = kallsyms_addresses[iter->pos];
366
367         iter->type = kallsyms_get_symbol_type(off);
368
369         off = kallsyms_expand_symbol(off, iter->name);
370
371         return off - iter->nameoff;
372 }
373
374 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
375 {
376         iter->name[0] = '\0';
377         iter->nameoff = get_symbol_offset(new_pos);
378         iter->pos = new_pos;
379 }
380
381 /* Returns false if pos at or past end of file. */
382 static int update_iter(struct kallsym_iter *iter, loff_t pos)
383 {
384         /* Module symbols can be accessed randomly. */
385         if (pos >= kallsyms_num_syms) {
386                 iter->pos = pos;
387                 return get_ksymbol_mod(iter);
388         }
389         
390         /* If we're not on the desired position, reset to new position. */
391         if (pos != iter->pos)
392                 reset_iter(iter, pos);
393
394         iter->nameoff += get_ksymbol_core(iter);
395         iter->pos++;
396
397         return 1;
398 }
399
400 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
401 {
402         (*pos)++;
403
404         if (!update_iter(m->private, *pos))
405                 return NULL;
406         return p;
407 }
408
409 static void *s_start(struct seq_file *m, loff_t *pos)
410 {
411         if (!update_iter(m->private, *pos))
412                 return NULL;
413         return m->private;
414 }
415
416 static void s_stop(struct seq_file *m, void *p)
417 {
418 }
419
420 static int s_show(struct seq_file *m, void *p)
421 {
422         struct kallsym_iter *iter = m->private;
423
424         /* Some debugging symbols have no name.  Ignore them. */ 
425         if (!iter->name[0])
426                 return 0;
427
428         if (iter->module_name[0]) {
429                 char type;
430
431                 /* Label it "global" if it is exported,
432                  * "local" if not exported. */
433                 type = iter->exported ? toupper(iter->type) :
434                                         tolower(iter->type);
435                 seq_printf(m, "%0*lx %c %s\t[%s]\n",
436                            (int)(2*sizeof(void*)),
437                            iter->value, type, iter->name, iter->module_name);
438         } else
439                 seq_printf(m, "%0*lx %c %s\n",
440                            (int)(2*sizeof(void*)),
441                            iter->value, iter->type, iter->name);
442         return 0;
443 }
444
445 static const struct seq_operations kallsyms_op = {
446         .start = s_start,
447         .next = s_next,
448         .stop = s_stop,
449         .show = s_show
450 };
451
452 static int kallsyms_open(struct inode *inode, struct file *file)
453 {
454         /* We keep iterator in m->private, since normal case is to
455          * s_start from where we left off, so we avoid doing
456          * using get_symbol_offset for every symbol */
457         struct kallsym_iter *iter;
458         int ret;
459
460         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
461         if (!iter)
462                 return -ENOMEM;
463         reset_iter(iter, 0);
464
465         ret = seq_open(file, &kallsyms_op);
466         if (ret == 0)
467                 ((struct seq_file *)file->private_data)->private = iter;
468         else
469                 kfree(iter);
470         return ret;
471 }
472
473 static const struct file_operations kallsyms_operations = {
474         .open = kallsyms_open,
475         .read = seq_read,
476         .llseek = seq_lseek,
477         .release = seq_release_private,
478 };
479
480 static int __init kallsyms_init(void)
481 {
482         struct proc_dir_entry *entry;
483
484         entry = create_proc_entry("kallsyms", 0444, NULL);
485         if (entry)
486                 entry->proc_fops = &kallsyms_operations;
487         return 0;
488 }
489 __initcall(kallsyms_init);
490
491 EXPORT_SYMBOL(__print_symbol);
492 EXPORT_SYMBOL_GPL(sprint_symbol);