x86: idle wakeup event in the HLT loop
[linux-2.6] / 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_extratext(unsigned long addr)
57 {
58         if (addr >= (unsigned long)_sextratext
59             && addr <= (unsigned long)_eextratext)
60                 return 1;
61         return 0;
62 }
63
64 static inline int is_kernel_text(unsigned long addr)
65 {
66         if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext)
67                 return 1;
68         return in_gate_area_no_task(addr);
69 }
70
71 static inline int is_kernel(unsigned long addr)
72 {
73         if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
74                 return 1;
75         return in_gate_area_no_task(addr);
76 }
77
78 static int is_ksym_addr(unsigned long addr)
79 {
80         if (all_var)
81                 return is_kernel(addr);
82
83         return is_kernel_text(addr) || is_kernel_inittext(addr) ||
84                 is_kernel_extratext(addr);
85 }
86
87 /* expand a compressed symbol data into the resulting uncompressed string,
88    given the offset to where the symbol is in the compressed stream */
89 static unsigned int kallsyms_expand_symbol(unsigned int off, char *result)
90 {
91         int len, skipped_first = 0;
92         const u8 *tptr, *data;
93
94         /* get the compressed symbol length from the first symbol byte */
95         data = &kallsyms_names[off];
96         len = *data;
97         data++;
98
99         /* update the offset to return the offset for the next symbol on
100          * the compressed stream */
101         off += len + 1;
102
103         /* for every byte on the compressed symbol data, copy the table
104            entry for that byte */
105         while(len) {
106                 tptr = &kallsyms_token_table[ kallsyms_token_index[*data] ];
107                 data++;
108                 len--;
109
110                 while (*tptr) {
111                         if(skipped_first) {
112                                 *result = *tptr;
113                                 result++;
114                         } else
115                                 skipped_first = 1;
116                         tptr++;
117                 }
118         }
119
120         *result = '\0';
121
122         /* return to offset to the next symbol */
123         return off;
124 }
125
126 /* get symbol type information. This is encoded as a single char at the
127  * begining of the symbol name */
128 static char kallsyms_get_symbol_type(unsigned int off)
129 {
130         /* get just the first code, look it up in the token table, and return the
131          * first char from this token */
132         return kallsyms_token_table[ kallsyms_token_index[ kallsyms_names[off+1] ] ];
133 }
134
135
136 /* find the offset on the compressed stream given and index in the
137  * kallsyms array */
138 static unsigned int get_symbol_offset(unsigned long pos)
139 {
140         const u8 *name;
141         int i;
142
143         /* use the closest marker we have. We have markers every 256 positions,
144          * so that should be close enough */
145         name = &kallsyms_names[ kallsyms_markers[pos>>8] ];
146
147         /* sequentially scan all the symbols up to the point we're searching for.
148          * Every symbol is stored in a [<len>][<len> bytes of data] format, so we
149          * just need to add the len to the current pointer for every symbol we
150          * wish to skip */
151         for(i = 0; i < (pos&0xFF); i++)
152                 name = name + (*name) + 1;
153
154         return name - kallsyms_names;
155 }
156
157 /* Lookup the address for this symbol. Returns 0 if not found. */
158 unsigned long kallsyms_lookup_name(const char *name)
159 {
160         char namebuf[KSYM_NAME_LEN];
161         unsigned long i;
162         unsigned int off;
163
164         for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
165                 off = kallsyms_expand_symbol(off, namebuf);
166
167                 if (strcmp(namebuf, name) == 0)
168                         return kallsyms_addresses[i];
169         }
170         return module_kallsyms_lookup_name(name);
171 }
172
173 static unsigned long get_symbol_pos(unsigned long addr,
174                                     unsigned long *symbolsize,
175                                     unsigned long *offset)
176 {
177         unsigned long symbol_start = 0, symbol_end = 0;
178         unsigned long i, low, high, mid;
179
180         /* This kernel should never had been booted. */
181         BUG_ON(!kallsyms_addresses);
182
183         /* do a binary search on the sorted kallsyms_addresses array */
184         low = 0;
185         high = kallsyms_num_syms;
186
187         while (high - low > 1) {
188                 mid = (low + high) / 2;
189                 if (kallsyms_addresses[mid] <= addr)
190                         low = mid;
191                 else
192                         high = mid;
193         }
194
195         /*
196          * search for the first aliased symbol. Aliased
197          * symbols are symbols with the same address
198          */
199         while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low])
200                 --low;
201
202         symbol_start = kallsyms_addresses[low];
203
204         /* Search for next non-aliased symbol */
205         for (i = low + 1; i < kallsyms_num_syms; i++) {
206                 if (kallsyms_addresses[i] > symbol_start) {
207                         symbol_end = kallsyms_addresses[i];
208                         break;
209                 }
210         }
211
212         /* if we found no next symbol, we use the end of the section */
213         if (!symbol_end) {
214                 if (is_kernel_inittext(addr))
215                         symbol_end = (unsigned long)_einittext;
216                 else if (all_var)
217                         symbol_end = (unsigned long)_end;
218                 else
219                         symbol_end = (unsigned long)_etext;
220         }
221
222         if (symbolsize)
223                 *symbolsize = symbol_end - symbol_start;
224         if (offset)
225                 *offset = addr - symbol_start;
226
227         return low;
228 }
229
230 /*
231  * Lookup an address but don't bother to find any names.
232  */
233 int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
234                                 unsigned long *offset)
235 {
236         char namebuf[KSYM_NAME_LEN];
237         if (is_ksym_addr(addr))
238                 return !!get_symbol_pos(addr, symbolsize, offset);
239
240         return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
241 }
242
243 /*
244  * Lookup an address
245  * - modname is set to NULL if it's in the kernel
246  * - we guarantee that the returned name is valid until we reschedule even if
247  *   it resides in a module
248  * - we also guarantee that modname will be valid until rescheduled
249  */
250 const char *kallsyms_lookup(unsigned long addr,
251                             unsigned long *symbolsize,
252                             unsigned long *offset,
253                             char **modname, char *namebuf)
254 {
255         namebuf[KSYM_NAME_LEN - 1] = 0;
256         namebuf[0] = 0;
257
258         if (is_ksym_addr(addr)) {
259                 unsigned long pos;
260
261                 pos = get_symbol_pos(addr, symbolsize, offset);
262                 /* Grab name */
263                 kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);
264                 if (modname)
265                         *modname = NULL;
266                 return namebuf;
267         }
268
269         /* see if it's in a module */
270         return module_address_lookup(addr, symbolsize, offset, modname,
271                                      namebuf);
272         return NULL;
273 }
274
275 int lookup_symbol_name(unsigned long addr, char *symname)
276 {
277         symname[0] = '\0';
278         symname[KSYM_NAME_LEN - 1] = '\0';
279
280         if (is_ksym_addr(addr)) {
281                 unsigned long pos;
282
283                 pos = get_symbol_pos(addr, NULL, NULL);
284                 /* Grab name */
285                 kallsyms_expand_symbol(get_symbol_offset(pos), symname);
286                 return 0;
287         }
288         /* see if it's in a module */
289         return lookup_module_symbol_name(addr, symname);
290 }
291
292 int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
293                         unsigned long *offset, char *modname, char *name)
294 {
295         name[0] = '\0';
296         name[KSYM_NAME_LEN - 1] = '\0';
297
298         if (is_ksym_addr(addr)) {
299                 unsigned long pos;
300
301                 pos = get_symbol_pos(addr, size, offset);
302                 /* Grab name */
303                 kallsyms_expand_symbol(get_symbol_offset(pos), name);
304                 modname[0] = '\0';
305                 return 0;
306         }
307         /* see if it's in a module */
308         return lookup_module_symbol_attrs(addr, size, offset, modname, name);
309 }
310
311 /* Look up a kernel symbol and return it in a text buffer. */
312 int sprint_symbol(char *buffer, unsigned long address)
313 {
314         char *modname;
315         const char *name;
316         unsigned long offset, size;
317         char namebuf[KSYM_NAME_LEN];
318
319         name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);
320         if (!name)
321                 return sprintf(buffer, "0x%lx", address);
322
323         if (modname)
324                 return sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset,
325                                 size, modname);
326         else
327                 return sprintf(buffer, "%s+%#lx/%#lx", name, offset, size);
328 }
329
330 /* Look up a kernel symbol and print it to the kernel messages. */
331 void __print_symbol(const char *fmt, unsigned long address)
332 {
333         char buffer[KSYM_SYMBOL_LEN];
334
335         sprint_symbol(buffer, address);
336
337         printk(fmt, buffer);
338 }
339
340 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
341 struct kallsym_iter
342 {
343         loff_t pos;
344         unsigned long value;
345         unsigned int nameoff; /* If iterating in core kernel symbols */
346         char type;
347         char name[KSYM_NAME_LEN];
348         char module_name[MODULE_NAME_LEN];
349         int exported;
350 };
351
352 static int get_ksymbol_mod(struct kallsym_iter *iter)
353 {
354         if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
355                                 &iter->type, iter->name, iter->module_name,
356                                 &iter->exported) < 0)
357                 return 0;
358         return 1;
359 }
360
361 /* Returns space to next name. */
362 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
363 {
364         unsigned off = iter->nameoff;
365
366         iter->module_name[0] = '\0';
367         iter->value = kallsyms_addresses[iter->pos];
368
369         iter->type = kallsyms_get_symbol_type(off);
370
371         off = kallsyms_expand_symbol(off, iter->name);
372
373         return off - iter->nameoff;
374 }
375
376 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
377 {
378         iter->name[0] = '\0';
379         iter->nameoff = get_symbol_offset(new_pos);
380         iter->pos = new_pos;
381 }
382
383 /* Returns false if pos at or past end of file. */
384 static int update_iter(struct kallsym_iter *iter, loff_t pos)
385 {
386         /* Module symbols can be accessed randomly. */
387         if (pos >= kallsyms_num_syms) {
388                 iter->pos = pos;
389                 return get_ksymbol_mod(iter);
390         }
391         
392         /* If we're not on the desired position, reset to new position. */
393         if (pos != iter->pos)
394                 reset_iter(iter, pos);
395
396         iter->nameoff += get_ksymbol_core(iter);
397         iter->pos++;
398
399         return 1;
400 }
401
402 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
403 {
404         (*pos)++;
405
406         if (!update_iter(m->private, *pos))
407                 return NULL;
408         return p;
409 }
410
411 static void *s_start(struct seq_file *m, loff_t *pos)
412 {
413         if (!update_iter(m->private, *pos))
414                 return NULL;
415         return m->private;
416 }
417
418 static void s_stop(struct seq_file *m, void *p)
419 {
420 }
421
422 static int s_show(struct seq_file *m, void *p)
423 {
424         struct kallsym_iter *iter = m->private;
425
426         /* Some debugging symbols have no name.  Ignore them. */ 
427         if (!iter->name[0])
428                 return 0;
429
430         if (iter->module_name[0]) {
431                 char type;
432
433                 /* Label it "global" if it is exported,
434                  * "local" if not exported. */
435                 type = iter->exported ? toupper(iter->type) :
436                                         tolower(iter->type);
437                 seq_printf(m, "%0*lx %c %s\t[%s]\n",
438                            (int)(2*sizeof(void*)),
439                            iter->value, type, iter->name, iter->module_name);
440         } else
441                 seq_printf(m, "%0*lx %c %s\n",
442                            (int)(2*sizeof(void*)),
443                            iter->value, iter->type, iter->name);
444         return 0;
445 }
446
447 static const struct seq_operations kallsyms_op = {
448         .start = s_start,
449         .next = s_next,
450         .stop = s_stop,
451         .show = s_show
452 };
453
454 static int kallsyms_open(struct inode *inode, struct file *file)
455 {
456         /* We keep iterator in m->private, since normal case is to
457          * s_start from where we left off, so we avoid doing
458          * using get_symbol_offset for every symbol */
459         struct kallsym_iter *iter;
460         int ret;
461
462         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
463         if (!iter)
464                 return -ENOMEM;
465         reset_iter(iter, 0);
466
467         ret = seq_open(file, &kallsyms_op);
468         if (ret == 0)
469                 ((struct seq_file *)file->private_data)->private = iter;
470         else
471                 kfree(iter);
472         return ret;
473 }
474
475 static const struct file_operations kallsyms_operations = {
476         .open = kallsyms_open,
477         .read = seq_read,
478         .llseek = seq_lseek,
479         .release = seq_release_private,
480 };
481
482 static int __init kallsyms_init(void)
483 {
484         struct proc_dir_entry *entry;
485
486         entry = create_proc_entry("kallsyms", 0444, NULL);
487         if (entry)
488                 entry->proc_fops = &kallsyms_operations;
489         return 0;
490 }
491 __initcall(kallsyms_init);
492
493 EXPORT_SYMBOL(__print_symbol);
494 EXPORT_SYMBOL_GPL(sprint_symbol);