projects/linux·blob v2.6.21 · refs

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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 <[email protected]> IBM Corporation
7 *
8 * ChangeLog:
9 *
10 * (25/Aug/2004) Paulo Marques <[email protected]>
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 */
34extern const unsigned long kallsyms_addresses[] __attribute__((weak));
35extern const unsigned long kallsyms_num_syms __attribute__((weak));
36extern const u8 kallsyms_names[] __attribute__((weak));
37
38extern const u8 kallsyms_token_table[] __attribute__((weak));
39extern const u16 kallsyms_token_index[] __attribute__((weak));
40
41extern const unsigned long kallsyms_markers[] __attribute__((weak));
42
43static 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
51static 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
59static 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
66static 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
73static 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 */
84static 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 */
123static 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 */
133static 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. */
153unsigned long kallsyms_lookup_name(const char *name)
154{
155 char namebuf[KSYM_NAME_LEN+1];
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
168static 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 *symbolsize = symbol_end - symbol_start;
218 *offset = addr - symbol_start;
219
220 return low;
221}
222
223/*
224 * Lookup an address but don't bother to find any names.
225 */
226int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
227 unsigned long *offset)
228{
229 if (is_ksym_addr(addr))
230 return !!get_symbol_pos(addr, symbolsize, offset);
231
232 return !!module_address_lookup(addr, symbolsize, offset, NULL);
233}
234
235/*
236 * Lookup an address
237 * - modname is set to NULL if it's in the kernel
238 * - we guarantee that the returned name is valid until we reschedule even if
239 * it resides in a module
240 * - we also guarantee that modname will be valid until rescheduled
241 */
242const char *kallsyms_lookup(unsigned long addr,
243 unsigned long *symbolsize,
244 unsigned long *offset,
245 char **modname, char *namebuf)
246{
247 const char *msym;
248
249 namebuf[KSYM_NAME_LEN] = 0;
250 namebuf[0] = 0;
251
252 if (is_ksym_addr(addr)) {
253 unsigned long pos;
254
255 pos = get_symbol_pos(addr, symbolsize, offset);
256 /* Grab name */
257 kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);
258 *modname = NULL;
259 return namebuf;
260 }
261
262 /* see if it's in a module */
263 msym = module_address_lookup(addr, symbolsize, offset, modname);
264 if (msym)
265 return strncpy(namebuf, msym, KSYM_NAME_LEN);
266
267 return NULL;
268}
269
270/* Replace "%s" in format with address, or returns -errno. */
271void __print_symbol(const char *fmt, unsigned long address)
272{
273 char *modname;
274 const char *name;
275 unsigned long offset, size;
276 char namebuf[KSYM_NAME_LEN+1];
277 char buffer[sizeof("%s+%#lx/%#lx [%s]") + KSYM_NAME_LEN +
278 2*(BITS_PER_LONG*3/10) + MODULE_NAME_LEN + 1];
279
280 name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);
281
282 if (!name)
283 sprintf(buffer, "0x%lx", address);
284 else {
285 if (modname)
286 sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset,
287 size, modname);
288 else
289 sprintf(buffer, "%s+%#lx/%#lx", name, offset, size);
290 }
291 printk(fmt, buffer);
292}
293
294/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
295struct kallsym_iter
296{
297 loff_t pos;
298 struct module *owner;
299 unsigned long value;
300 unsigned int nameoff; /* If iterating in core kernel symbols */
301 char type;
302 char name[KSYM_NAME_LEN+1];
303};
304
305static int get_ksymbol_mod(struct kallsym_iter *iter)
306{
307 iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms,
308 &iter->value, &iter->type,
309 iter->name, sizeof(iter->name));
310 if (iter->owner == NULL)
311 return 0;
312
313 /* Label it "global" if it is exported, "local" if not exported. */
314 iter->type = is_exported(iter->name, iter->owner)
315 ? toupper(iter->type) : tolower(iter->type);
316
317 return 1;
318}
319
320/* Returns space to next name. */
321static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
322{
323 unsigned off = iter->nameoff;
324
325 iter->owner = NULL;
326 iter->value = kallsyms_addresses[iter->pos];
327
328 iter->type = kallsyms_get_symbol_type(off);
329
330 off = kallsyms_expand_symbol(off, iter->name);
331
332 return off - iter->nameoff;
333}
334
335static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
336{
337 iter->name[0] = '\0';
338 iter->nameoff = get_symbol_offset(new_pos);
339 iter->pos = new_pos;
340}
341
342/* Returns false if pos at or past end of file. */
343static int update_iter(struct kallsym_iter *iter, loff_t pos)
344{
345 /* Module symbols can be accessed randomly. */
346 if (pos >= kallsyms_num_syms) {
347 iter->pos = pos;
348 return get_ksymbol_mod(iter);
349 }
350
351 /* If we're not on the desired position, reset to new position. */
352 if (pos != iter->pos)
353 reset_iter(iter, pos);
354
355 iter->nameoff += get_ksymbol_core(iter);
356 iter->pos++;
357
358 return 1;
359}
360
361static void *s_next(struct seq_file *m, void *p, loff_t *pos)
362{
363 (*pos)++;
364
365 if (!update_iter(m->private, *pos))
366 return NULL;
367 return p;
368}
369
370static void *s_start(struct seq_file *m, loff_t *pos)
371{
372 if (!update_iter(m->private, *pos))
373 return NULL;
374 return m->private;
375}
376
377static void s_stop(struct seq_file *m, void *p)
378{
379}
380
381static int s_show(struct seq_file *m, void *p)
382{
383 struct kallsym_iter *iter = m->private;
384
385 /* Some debugging symbols have no name. Ignore them. */
386 if (!iter->name[0])
387 return 0;
388
389 if (iter->owner)
390 seq_printf(m, "%0*lx %c %s\t[%s]\n",
391 (int)(2*sizeof(void*)),
392 iter->value, iter->type, iter->name,
393 module_name(iter->owner));
394 else
395 seq_printf(m, "%0*lx %c %s\n",
396 (int)(2*sizeof(void*)),
397 iter->value, iter->type, iter->name);
398 return 0;
399}
400
401static const struct seq_operations kallsyms_op = {
402 .start = s_start,
403 .next = s_next,
404 .stop = s_stop,
405 .show = s_show
406};
407
408static int kallsyms_open(struct inode *inode, struct file *file)
409{
410 /* We keep iterator in m->private, since normal case is to
411 * s_start from where we left off, so we avoid doing
412 * using get_symbol_offset for every symbol */
413 struct kallsym_iter *iter;
414 int ret;
415
416 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
417 if (!iter)
418 return -ENOMEM;
419 reset_iter(iter, 0);
420
421 ret = seq_open(file, &kallsyms_op);
422 if (ret == 0)
423 ((struct seq_file *)file->private_data)->private = iter;
424 else
425 kfree(iter);
426 return ret;
427}
428
429static int kallsyms_release(struct inode *inode, struct file *file)
430{
431 struct seq_file *m = (struct seq_file *)file->private_data;
432 kfree(m->private);
433 return seq_release(inode, file);
434}
435
436static const struct file_operations kallsyms_operations = {
437 .open = kallsyms_open,
438 .read = seq_read,
439 .llseek = seq_lseek,
440 .release = kallsyms_release,
441};
442
443static int __init kallsyms_init(void)
444{
445 struct proc_dir_entry *entry;
446
447 entry = create_proc_entry("kallsyms", 0444, NULL);
448 if (entry)
449 entry->proc_fops = &kallsyms_operations;
450 return 0;
451}
452__initcall(kallsyms_init);
453
454EXPORT_SYMBOL(__print_symbol);