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1da177e4 LT |
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/mm.h> | |
22 | ||
23 | #include <asm/sections.h> | |
24 | ||
25 | #ifdef CONFIG_KALLSYMS_ALL | |
26 | #define all_var 1 | |
27 | #else | |
28 | #define all_var 0 | |
29 | #endif | |
30 | ||
31 | /* These will be re-linked against their real values during the second link stage */ | |
32 | extern unsigned long kallsyms_addresses[] __attribute__((weak)); | |
33 | extern unsigned long kallsyms_num_syms __attribute__((weak,section("data"))); | |
34 | extern u8 kallsyms_names[] __attribute__((weak)); | |
35 | ||
36 | extern u8 kallsyms_token_table[] __attribute__((weak)); | |
37 | extern u16 kallsyms_token_index[] __attribute__((weak)); | |
38 | ||
39 | extern unsigned long kallsyms_markers[] __attribute__((weak)); | |
40 | ||
41 | static inline int is_kernel_inittext(unsigned long addr) | |
42 | { | |
43 | if (addr >= (unsigned long)_sinittext | |
44 | && addr <= (unsigned long)_einittext) | |
45 | return 1; | |
46 | return 0; | |
47 | } | |
48 | ||
075d6eb1 DW |
49 | static inline int is_kernel_extratext(unsigned long addr) |
50 | { | |
51 | if (addr >= (unsigned long)_sextratext | |
52 | && addr <= (unsigned long)_eextratext) | |
53 | return 1; | |
54 | return 0; | |
55 | } | |
56 | ||
1da177e4 LT |
57 | static inline int is_kernel_text(unsigned long addr) |
58 | { | |
59 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) | |
60 | return 1; | |
61 | return in_gate_area_no_task(addr); | |
62 | } | |
63 | ||
64 | static inline int is_kernel(unsigned long addr) | |
65 | { | |
66 | if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) | |
67 | return 1; | |
68 | return in_gate_area_no_task(addr); | |
69 | } | |
70 | ||
71 | /* expand a compressed symbol data into the resulting uncompressed string, | |
72 | given the offset to where the symbol is in the compressed stream */ | |
73 | static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) | |
74 | { | |
75 | int len, skipped_first = 0; | |
76 | u8 *tptr, *data; | |
77 | ||
78 | /* get the compressed symbol length from the first symbol byte */ | |
79 | data = &kallsyms_names[off]; | |
80 | len = *data; | |
81 | data++; | |
82 | ||
83 | /* update the offset to return the offset for the next symbol on | |
84 | * the compressed stream */ | |
85 | off += len + 1; | |
86 | ||
87 | /* for every byte on the compressed symbol data, copy the table | |
88 | entry for that byte */ | |
89 | while(len) { | |
90 | tptr = &kallsyms_token_table[ kallsyms_token_index[*data] ]; | |
91 | data++; | |
92 | len--; | |
93 | ||
94 | while (*tptr) { | |
95 | if(skipped_first) { | |
96 | *result = *tptr; | |
97 | result++; | |
98 | } else | |
99 | skipped_first = 1; | |
100 | tptr++; | |
101 | } | |
102 | } | |
103 | ||
104 | *result = '\0'; | |
105 | ||
106 | /* return to offset to the next symbol */ | |
107 | return off; | |
108 | } | |
109 | ||
110 | /* get symbol type information. This is encoded as a single char at the | |
111 | * begining of the symbol name */ | |
112 | static char kallsyms_get_symbol_type(unsigned int off) | |
113 | { | |
114 | /* get just the first code, look it up in the token table, and return the | |
115 | * first char from this token */ | |
116 | return kallsyms_token_table[ kallsyms_token_index[ kallsyms_names[off+1] ] ]; | |
117 | } | |
118 | ||
119 | ||
120 | /* find the offset on the compressed stream given and index in the | |
121 | * kallsyms array */ | |
122 | static unsigned int get_symbol_offset(unsigned long pos) | |
123 | { | |
124 | u8 *name; | |
125 | int i; | |
126 | ||
127 | /* use the closest marker we have. We have markers every 256 positions, | |
128 | * so that should be close enough */ | |
129 | name = &kallsyms_names[ kallsyms_markers[pos>>8] ]; | |
130 | ||
131 | /* sequentially scan all the symbols up to the point we're searching for. | |
132 | * Every symbol is stored in a [<len>][<len> bytes of data] format, so we | |
133 | * just need to add the len to the current pointer for every symbol we | |
134 | * wish to skip */ | |
135 | for(i = 0; i < (pos&0xFF); i++) | |
136 | name = name + (*name) + 1; | |
137 | ||
138 | return name - kallsyms_names; | |
139 | } | |
140 | ||
141 | /* Lookup the address for this symbol. Returns 0 if not found. */ | |
142 | unsigned long kallsyms_lookup_name(const char *name) | |
143 | { | |
144 | char namebuf[KSYM_NAME_LEN+1]; | |
145 | unsigned long i; | |
146 | unsigned int off; | |
147 | ||
148 | for (i = 0, off = 0; i < kallsyms_num_syms; i++) { | |
149 | off = kallsyms_expand_symbol(off, namebuf); | |
150 | ||
151 | if (strcmp(namebuf, name) == 0) | |
152 | return kallsyms_addresses[i]; | |
153 | } | |
154 | return module_kallsyms_lookup_name(name); | |
155 | } | |
156 | EXPORT_SYMBOL_GPL(kallsyms_lookup_name); | |
157 | ||
158 | /* | |
159 | * Lookup an address | |
160 | * - modname is set to NULL if it's in the kernel | |
161 | * - we guarantee that the returned name is valid until we reschedule even if | |
162 | * it resides in a module | |
163 | * - we also guarantee that modname will be valid until rescheduled | |
164 | */ | |
165 | const char *kallsyms_lookup(unsigned long addr, | |
166 | unsigned long *symbolsize, | |
167 | unsigned long *offset, | |
168 | char **modname, char *namebuf) | |
169 | { | |
170 | unsigned long i, low, high, mid; | |
171 | const char *msym; | |
172 | ||
173 | /* This kernel should never had been booted. */ | |
174 | BUG_ON(!kallsyms_addresses); | |
175 | ||
176 | namebuf[KSYM_NAME_LEN] = 0; | |
177 | namebuf[0] = 0; | |
178 | ||
179 | if ((all_var && is_kernel(addr)) || | |
075d6eb1 DW |
180 | (!all_var && (is_kernel_text(addr) || is_kernel_inittext(addr) || |
181 | is_kernel_extratext(addr)))) { | |
182 | unsigned long symbol_end = 0; | |
1da177e4 LT |
183 | |
184 | /* do a binary search on the sorted kallsyms_addresses array */ | |
185 | low = 0; | |
186 | high = kallsyms_num_syms; | |
187 | ||
188 | while (high-low > 1) { | |
189 | mid = (low + high) / 2; | |
190 | if (kallsyms_addresses[mid] <= addr) low = mid; | |
191 | else high = mid; | |
192 | } | |
193 | ||
194 | /* search for the first aliased symbol. Aliased symbols are | |
195 | symbols with the same address */ | |
196 | while (low && kallsyms_addresses[low - 1] == kallsyms_addresses[low]) | |
197 | --low; | |
198 | ||
199 | /* Grab name */ | |
200 | kallsyms_expand_symbol(get_symbol_offset(low), namebuf); | |
201 | ||
202 | /* Search for next non-aliased symbol */ | |
203 | for (i = low + 1; i < kallsyms_num_syms; i++) { | |
204 | if (kallsyms_addresses[i] > kallsyms_addresses[low]) { | |
205 | symbol_end = kallsyms_addresses[i]; | |
206 | break; | |
207 | } | |
208 | } | |
209 | ||
210 | /* if we found no next symbol, we use the end of the section */ | |
211 | if (!symbol_end) { | |
212 | if (is_kernel_inittext(addr)) | |
213 | symbol_end = (unsigned long)_einittext; | |
214 | else | |
215 | symbol_end = all_var ? (unsigned long)_end : (unsigned long)_etext; | |
216 | } | |
217 | ||
218 | *symbolsize = symbol_end - kallsyms_addresses[low]; | |
219 | *modname = NULL; | |
220 | *offset = addr - kallsyms_addresses[low]; | |
221 | return namebuf; | |
222 | } | |
223 | ||
224 | /* see if it's in a module */ | |
225 | msym = module_address_lookup(addr, symbolsize, offset, modname); | |
226 | if (msym) | |
227 | return strncpy(namebuf, msym, KSYM_NAME_LEN); | |
228 | ||
229 | return NULL; | |
230 | } | |
231 | ||
232 | /* Replace "%s" in format with address, or returns -errno. */ | |
233 | void __print_symbol(const char *fmt, unsigned long address) | |
234 | { | |
235 | char *modname; | |
236 | const char *name; | |
237 | unsigned long offset, size; | |
238 | char namebuf[KSYM_NAME_LEN+1]; | |
239 | char buffer[sizeof("%s+%#lx/%#lx [%s]") + KSYM_NAME_LEN + | |
240 | 2*(BITS_PER_LONG*3/10) + MODULE_NAME_LEN + 1]; | |
241 | ||
242 | name = kallsyms_lookup(address, &size, &offset, &modname, namebuf); | |
243 | ||
244 | if (!name) | |
245 | sprintf(buffer, "0x%lx", address); | |
246 | else { | |
247 | if (modname) | |
248 | sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset, | |
249 | size, modname); | |
250 | else | |
251 | sprintf(buffer, "%s+%#lx/%#lx", name, offset, size); | |
252 | } | |
253 | printk(fmt, buffer); | |
254 | } | |
255 | ||
256 | /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ | |
257 | struct kallsym_iter | |
258 | { | |
259 | loff_t pos; | |
260 | struct module *owner; | |
261 | unsigned long value; | |
262 | unsigned int nameoff; /* If iterating in core kernel symbols */ | |
263 | char type; | |
264 | char name[KSYM_NAME_LEN+1]; | |
265 | }; | |
266 | ||
267 | /* Only label it "global" if it is exported. */ | |
268 | static void upcase_if_global(struct kallsym_iter *iter) | |
269 | { | |
270 | if (is_exported(iter->name, iter->owner)) | |
271 | iter->type += 'A' - 'a'; | |
272 | } | |
273 | ||
274 | static int get_ksymbol_mod(struct kallsym_iter *iter) | |
275 | { | |
276 | iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms, | |
277 | &iter->value, | |
278 | &iter->type, iter->name); | |
279 | if (iter->owner == NULL) | |
280 | return 0; | |
281 | ||
282 | upcase_if_global(iter); | |
283 | return 1; | |
284 | } | |
285 | ||
286 | /* Returns space to next name. */ | |
287 | static unsigned long get_ksymbol_core(struct kallsym_iter *iter) | |
288 | { | |
289 | unsigned off = iter->nameoff; | |
290 | ||
291 | iter->owner = NULL; | |
292 | iter->value = kallsyms_addresses[iter->pos]; | |
293 | ||
294 | iter->type = kallsyms_get_symbol_type(off); | |
295 | ||
296 | off = kallsyms_expand_symbol(off, iter->name); | |
297 | ||
298 | return off - iter->nameoff; | |
299 | } | |
300 | ||
301 | static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) | |
302 | { | |
303 | iter->name[0] = '\0'; | |
304 | iter->nameoff = get_symbol_offset(new_pos); | |
305 | iter->pos = new_pos; | |
306 | } | |
307 | ||
308 | /* Returns false if pos at or past end of file. */ | |
309 | static int update_iter(struct kallsym_iter *iter, loff_t pos) | |
310 | { | |
311 | /* Module symbols can be accessed randomly. */ | |
312 | if (pos >= kallsyms_num_syms) { | |
313 | iter->pos = pos; | |
314 | return get_ksymbol_mod(iter); | |
315 | } | |
316 | ||
317 | /* If we're not on the desired position, reset to new position. */ | |
318 | if (pos != iter->pos) | |
319 | reset_iter(iter, pos); | |
320 | ||
321 | iter->nameoff += get_ksymbol_core(iter); | |
322 | iter->pos++; | |
323 | ||
324 | return 1; | |
325 | } | |
326 | ||
327 | static void *s_next(struct seq_file *m, void *p, loff_t *pos) | |
328 | { | |
329 | (*pos)++; | |
330 | ||
331 | if (!update_iter(m->private, *pos)) | |
332 | return NULL; | |
333 | return p; | |
334 | } | |
335 | ||
336 | static void *s_start(struct seq_file *m, loff_t *pos) | |
337 | { | |
338 | if (!update_iter(m->private, *pos)) | |
339 | return NULL; | |
340 | return m->private; | |
341 | } | |
342 | ||
343 | static void s_stop(struct seq_file *m, void *p) | |
344 | { | |
345 | } | |
346 | ||
347 | static int s_show(struct seq_file *m, void *p) | |
348 | { | |
349 | struct kallsym_iter *iter = m->private; | |
350 | ||
351 | /* Some debugging symbols have no name. Ignore them. */ | |
352 | if (!iter->name[0]) | |
353 | return 0; | |
354 | ||
355 | if (iter->owner) | |
356 | seq_printf(m, "%0*lx %c %s\t[%s]\n", | |
357 | (int)(2*sizeof(void*)), | |
358 | iter->value, iter->type, iter->name, | |
359 | module_name(iter->owner)); | |
360 | else | |
361 | seq_printf(m, "%0*lx %c %s\n", | |
362 | (int)(2*sizeof(void*)), | |
363 | iter->value, iter->type, iter->name); | |
364 | return 0; | |
365 | } | |
366 | ||
367 | static struct seq_operations kallsyms_op = { | |
368 | .start = s_start, | |
369 | .next = s_next, | |
370 | .stop = s_stop, | |
371 | .show = s_show | |
372 | }; | |
373 | ||
374 | static int kallsyms_open(struct inode *inode, struct file *file) | |
375 | { | |
376 | /* We keep iterator in m->private, since normal case is to | |
377 | * s_start from where we left off, so we avoid doing | |
378 | * using get_symbol_offset for every symbol */ | |
379 | struct kallsym_iter *iter; | |
380 | int ret; | |
381 | ||
382 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
383 | if (!iter) | |
384 | return -ENOMEM; | |
385 | reset_iter(iter, 0); | |
386 | ||
387 | ret = seq_open(file, &kallsyms_op); | |
388 | if (ret == 0) | |
389 | ((struct seq_file *)file->private_data)->private = iter; | |
390 | else | |
391 | kfree(iter); | |
392 | return ret; | |
393 | } | |
394 | ||
395 | static int kallsyms_release(struct inode *inode, struct file *file) | |
396 | { | |
397 | struct seq_file *m = (struct seq_file *)file->private_data; | |
398 | kfree(m->private); | |
399 | return seq_release(inode, file); | |
400 | } | |
401 | ||
402 | static struct file_operations kallsyms_operations = { | |
403 | .open = kallsyms_open, | |
404 | .read = seq_read, | |
405 | .llseek = seq_lseek, | |
406 | .release = kallsyms_release, | |
407 | }; | |
408 | ||
409 | static int __init kallsyms_init(void) | |
410 | { | |
411 | struct proc_dir_entry *entry; | |
412 | ||
413 | entry = create_proc_entry("kallsyms", 0444, NULL); | |
414 | if (entry) | |
415 | entry->proc_fops = &kallsyms_operations; | |
416 | return 0; | |
417 | } | |
418 | __initcall(kallsyms_init); | |
419 | ||
420 | EXPORT_SYMBOL(__print_symbol); |