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