blob: 1627f8d6e0cdd5f918c30666f4434407df25c293 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 */
32extern unsigned long kallsyms_addresses[] __attribute__((weak));
33extern unsigned long kallsyms_num_syms __attribute__((weak,section("data")));
34extern u8 kallsyms_names[] __attribute__((weak));
35
36extern u8 kallsyms_token_table[] __attribute__((weak));
37extern u16 kallsyms_token_index[] __attribute__((weak));
38
39extern unsigned long kallsyms_markers[] __attribute__((weak));
40
41static 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
49static 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
56static 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 */
65static 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 */
104static 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 */
114static 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. */
134unsigned 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}
148EXPORT_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 */
157const 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. */
224void __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. */
248struct 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. */
259static void upcase_if_global(struct kallsym_iter *iter)
260{
261 if (is_exported(iter->name, iter->owner))
262 iter->type += 'A' - 'a';
263}
264
265static 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. */
278static 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
292static 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. */
300static 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
318static 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
327static 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
334static void s_stop(struct seq_file *m, void *p)
335{
336}
337
338static 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
358static struct seq_operations kallsyms_op = {
359 .start = s_start,
360 .next = s_next,
361 .stop = s_stop,
362 .show = s_show
363};
364
365static 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
386static 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
393static struct file_operations kallsyms_operations = {
394 .open = kallsyms_open,
395 .read = seq_read,
396 .llseek = seq_lseek,
397 .release = kallsyms_release,
398};
399
400static 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
411EXPORT_SYMBOL(__print_symbol);