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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 <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/kdb.h>
20#include <linux/err.h>
21#include <linux/proc_fs.h>
22#include <linux/sched.h> /* for cond_resched */
23#include <linux/mm.h>
24#include <linux/ctype.h>
25#include <linux/slab.h>
26#include <linux/compiler.h>
27
28#include <asm/sections.h>
29
30#ifdef CONFIG_KALLSYMS_ALL
31#define all_var 1
32#else
33#define all_var 0
34#endif
35
36/*
37 * These will be re-linked against their real values
38 * during the second link stage.
39 */
40extern const unsigned long kallsyms_addresses[] __weak;
41extern const int kallsyms_offsets[] __weak;
42extern const u8 kallsyms_names[] __weak;
43
44/*
45 * Tell the compiler that the count isn't in the small data section if the arch
46 * has one (eg: FRV).
47 */
48extern const unsigned long kallsyms_num_syms
49__attribute__((weak, section(".rodata")));
50
51extern const unsigned long kallsyms_relative_base
52__attribute__((weak, section(".rodata")));
53
54extern const u8 kallsyms_token_table[] __weak;
55extern const u16 kallsyms_token_index[] __weak;
56
57extern const unsigned long kallsyms_markers[] __weak;
58
59static inline int is_kernel_inittext(unsigned long addr)
60{
61 if (addr >= (unsigned long)_sinittext
62 && addr <= (unsigned long)_einittext)
63 return 1;
64 return 0;
65}
66
67static inline int is_kernel_text(unsigned long addr)
68{
69 if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) ||
70 arch_is_kernel_text(addr))
71 return 1;
72 return in_gate_area_no_mm(addr);
73}
74
75static inline int is_kernel(unsigned long addr)
76{
77 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
78 return 1;
79 return in_gate_area_no_mm(addr);
80}
81
82static int is_ksym_addr(unsigned long addr)
83{
84 if (all_var)
85 return is_kernel(addr);
86
87 return is_kernel_text(addr) || is_kernel_inittext(addr);
88}
89
90/*
91 * Expand a compressed symbol data into the resulting uncompressed string,
92 * if uncompressed string is too long (>= maxlen), it will be truncated,
93 * given the offset to where the symbol is in the compressed stream.
94 */
95static unsigned int kallsyms_expand_symbol(unsigned int off,
96 char *result, size_t maxlen)
97{
98 int len, skipped_first = 0;
99 const u8 *tptr, *data;
100
101 /* Get the compressed symbol length from the first symbol byte. */
102 data = &kallsyms_names[off];
103 len = *data;
104 data++;
105
106 /*
107 * Update the offset to return the offset for the next symbol on
108 * the compressed stream.
109 */
110 off += len + 1;
111
112 /*
113 * For every byte on the compressed symbol data, copy the table
114 * entry for that byte.
115 */
116 while (len) {
117 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
118 data++;
119 len--;
120
121 while (*tptr) {
122 if (skipped_first) {
123 if (maxlen <= 1)
124 goto tail;
125 *result = *tptr;
126 result++;
127 maxlen--;
128 } else
129 skipped_first = 1;
130 tptr++;
131 }
132 }
133
134tail:
135 if (maxlen)
136 *result = '\0';
137
138 /* Return to offset to the next symbol. */
139 return off;
140}
141
142/*
143 * Get symbol type information. This is encoded as a single char at the
144 * beginning of the symbol name.
145 */
146static char kallsyms_get_symbol_type(unsigned int off)
147{
148 /*
149 * Get just the first code, look it up in the token table,
150 * and return the first char from this token.
151 */
152 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
153}
154
155
156/*
157 * Find the offset on the compressed stream given and index in the
158 * kallsyms array.
159 */
160static unsigned int get_symbol_offset(unsigned long pos)
161{
162 const u8 *name;
163 int i;
164
165 /*
166 * Use the closest marker we have. We have markers every 256 positions,
167 * so that should be close enough.
168 */
169 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
170
171 /*
172 * Sequentially scan all the symbols up to the point we're searching
173 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
174 * so we just need to add the len to the current pointer for every
175 * symbol we wish to skip.
176 */
177 for (i = 0; i < (pos & 0xFF); i++)
178 name = name + (*name) + 1;
179
180 return name - kallsyms_names;
181}
182
183static unsigned long kallsyms_sym_address(int idx)
184{
185 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
186 return kallsyms_addresses[idx];
187
188 /* values are unsigned offsets if --absolute-percpu is not in effect */
189 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
190 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
191
192 /* ...otherwise, positive offsets are absolute values */
193 if (kallsyms_offsets[idx] >= 0)
194 return kallsyms_offsets[idx];
195
196 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
197 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
198}
199
200/* Lookup the address for this symbol. Returns 0 if not found. */
201unsigned long kallsyms_lookup_name(const char *name)
202{
203 char namebuf[KSYM_NAME_LEN];
204 unsigned long i;
205 unsigned int off;
206
207 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
208 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
209
210 if (strcmp(namebuf, name) == 0)
211 return kallsyms_sym_address(i);
212 }
213 return module_kallsyms_lookup_name(name);
214}
215EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
216
217int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
218 unsigned long),
219 void *data)
220{
221 char namebuf[KSYM_NAME_LEN];
222 unsigned long i;
223 unsigned int off;
224 int ret;
225
226 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
227 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
228 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
229 if (ret != 0)
230 return ret;
231 }
232 return module_kallsyms_on_each_symbol(fn, data);
233}
234EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
235
236static unsigned long get_symbol_pos(unsigned long addr,
237 unsigned long *symbolsize,
238 unsigned long *offset)
239{
240 unsigned long symbol_start = 0, symbol_end = 0;
241 unsigned long i, low, high, mid;
242
243 /* This kernel should never had been booted. */
244 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
245 BUG_ON(!kallsyms_addresses);
246 else
247 BUG_ON(!kallsyms_offsets);
248
249 /* Do a binary search on the sorted kallsyms_addresses array. */
250 low = 0;
251 high = kallsyms_num_syms;
252
253 while (high - low > 1) {
254 mid = low + (high - low) / 2;
255 if (kallsyms_sym_address(mid) <= addr)
256 low = mid;
257 else
258 high = mid;
259 }
260
261 /*
262 * Search for the first aliased symbol. Aliased
263 * symbols are symbols with the same address.
264 */
265 while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
266 --low;
267
268 symbol_start = kallsyms_sym_address(low);
269
270 /* Search for next non-aliased symbol. */
271 for (i = low + 1; i < kallsyms_num_syms; i++) {
272 if (kallsyms_sym_address(i) > symbol_start) {
273 symbol_end = kallsyms_sym_address(i);
274 break;
275 }
276 }
277
278 /* If we found no next symbol, we use the end of the section. */
279 if (!symbol_end) {
280 if (is_kernel_inittext(addr))
281 symbol_end = (unsigned long)_einittext;
282 else if (all_var)
283 symbol_end = (unsigned long)_end;
284 else
285 symbol_end = (unsigned long)_etext;
286 }
287
288 if (symbolsize)
289 *symbolsize = symbol_end - symbol_start;
290 if (offset)
291 *offset = addr - symbol_start;
292
293 return low;
294}
295
296/*
297 * Lookup an address but don't bother to find any names.
298 */
299int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
300 unsigned long *offset)
301{
302 char namebuf[KSYM_NAME_LEN];
303 if (is_ksym_addr(addr))
304 return !!get_symbol_pos(addr, symbolsize, offset);
305
306 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
307}
308
309/*
310 * Lookup an address
311 * - modname is set to NULL if it's in the kernel.
312 * - We guarantee that the returned name is valid until we reschedule even if.
313 * It resides in a module.
314 * - We also guarantee that modname will be valid until rescheduled.
315 */
316const char *kallsyms_lookup(unsigned long addr,
317 unsigned long *symbolsize,
318 unsigned long *offset,
319 char **modname, char *namebuf)
320{
321 namebuf[KSYM_NAME_LEN - 1] = 0;
322 namebuf[0] = 0;
323
324 if (is_ksym_addr(addr)) {
325 unsigned long pos;
326
327 pos = get_symbol_pos(addr, symbolsize, offset);
328 /* Grab name */
329 kallsyms_expand_symbol(get_symbol_offset(pos),
330 namebuf, KSYM_NAME_LEN);
331 if (modname)
332 *modname = NULL;
333 return namebuf;
334 }
335
336 /* See if it's in a module. */
337 return module_address_lookup(addr, symbolsize, offset, modname,
338 namebuf);
339}
340
341int lookup_symbol_name(unsigned long addr, char *symname)
342{
343 symname[0] = '\0';
344 symname[KSYM_NAME_LEN - 1] = '\0';
345
346 if (is_ksym_addr(addr)) {
347 unsigned long pos;
348
349 pos = get_symbol_pos(addr, NULL, NULL);
350 /* Grab name */
351 kallsyms_expand_symbol(get_symbol_offset(pos),
352 symname, KSYM_NAME_LEN);
353 return 0;
354 }
355 /* See if it's in a module. */
356 return lookup_module_symbol_name(addr, symname);
357}
358
359int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
360 unsigned long *offset, char *modname, char *name)
361{
362 name[0] = '\0';
363 name[KSYM_NAME_LEN - 1] = '\0';
364
365 if (is_ksym_addr(addr)) {
366 unsigned long pos;
367
368 pos = get_symbol_pos(addr, size, offset);
369 /* Grab name */
370 kallsyms_expand_symbol(get_symbol_offset(pos),
371 name, KSYM_NAME_LEN);
372 modname[0] = '\0';
373 return 0;
374 }
375 /* See if it's in a module. */
376 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
377}
378
379/* Look up a kernel symbol and return it in a text buffer. */
380static int __sprint_symbol(char *buffer, unsigned long address,
381 int symbol_offset, int add_offset)
382{
383 char *modname;
384 const char *name;
385 unsigned long offset, size;
386 int len;
387
388 address += symbol_offset;
389 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
390 if (!name)
391 return sprintf(buffer, "0x%lx", address - symbol_offset);
392
393 if (name != buffer)
394 strcpy(buffer, name);
395 len = strlen(buffer);
396 offset -= symbol_offset;
397
398 if (add_offset)
399 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
400
401 if (modname)
402 len += sprintf(buffer + len, " [%s]", modname);
403
404 return len;
405}
406
407/**
408 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
409 * @buffer: buffer to be stored
410 * @address: address to lookup
411 *
412 * This function looks up a kernel symbol with @address and stores its name,
413 * offset, size and module name to @buffer if possible. If no symbol was found,
414 * just saves its @address as is.
415 *
416 * This function returns the number of bytes stored in @buffer.
417 */
418int sprint_symbol(char *buffer, unsigned long address)
419{
420 return __sprint_symbol(buffer, address, 0, 1);
421}
422EXPORT_SYMBOL_GPL(sprint_symbol);
423
424/**
425 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
426 * @buffer: buffer to be stored
427 * @address: address to lookup
428 *
429 * This function looks up a kernel symbol with @address and stores its name
430 * and module name to @buffer if possible. If no symbol was found, just saves
431 * its @address as is.
432 *
433 * This function returns the number of bytes stored in @buffer.
434 */
435int sprint_symbol_no_offset(char *buffer, unsigned long address)
436{
437 return __sprint_symbol(buffer, address, 0, 0);
438}
439EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
440
441/**
442 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
443 * @buffer: buffer to be stored
444 * @address: address to lookup
445 *
446 * This function is for stack backtrace and does the same thing as
447 * sprint_symbol() but with modified/decreased @address. If there is a
448 * tail-call to the function marked "noreturn", gcc optimized out code after
449 * the call so that the stack-saved return address could point outside of the
450 * caller. This function ensures that kallsyms will find the original caller
451 * by decreasing @address.
452 *
453 * This function returns the number of bytes stored in @buffer.
454 */
455int sprint_backtrace(char *buffer, unsigned long address)
456{
457 return __sprint_symbol(buffer, address, -1, 1);
458}
459
460/* Look up a kernel symbol and print it to the kernel messages. */
461void __print_symbol(const char *fmt, unsigned long address)
462{
463 char buffer[KSYM_SYMBOL_LEN];
464
465 sprint_symbol(buffer, address);
466
467 printk(fmt, buffer);
468}
469EXPORT_SYMBOL(__print_symbol);
470
471/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
472struct kallsym_iter {
473 loff_t pos;
474 unsigned long value;
475 unsigned int nameoff; /* If iterating in core kernel symbols. */
476 char type;
477 char name[KSYM_NAME_LEN];
478 char module_name[MODULE_NAME_LEN];
479 int exported;
480};
481
482static int get_ksymbol_mod(struct kallsym_iter *iter)
483{
484 if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
485 &iter->type, iter->name, iter->module_name,
486 &iter->exported) < 0)
487 return 0;
488 return 1;
489}
490
491/* Returns space to next name. */
492static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
493{
494 unsigned off = iter->nameoff;
495
496 iter->module_name[0] = '\0';
497 iter->value = kallsyms_sym_address(iter->pos);
498
499 iter->type = kallsyms_get_symbol_type(off);
500
501 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
502
503 return off - iter->nameoff;
504}
505
506static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
507{
508 iter->name[0] = '\0';
509 iter->nameoff = get_symbol_offset(new_pos);
510 iter->pos = new_pos;
511}
512
513/* Returns false if pos at or past end of file. */
514static int update_iter(struct kallsym_iter *iter, loff_t pos)
515{
516 /* Module symbols can be accessed randomly. */
517 if (pos >= kallsyms_num_syms) {
518 iter->pos = pos;
519 return get_ksymbol_mod(iter);
520 }
521
522 /* If we're not on the desired position, reset to new position. */
523 if (pos != iter->pos)
524 reset_iter(iter, pos);
525
526 iter->nameoff += get_ksymbol_core(iter);
527 iter->pos++;
528
529 return 1;
530}
531
532static void *s_next(struct seq_file *m, void *p, loff_t *pos)
533{
534 (*pos)++;
535
536 if (!update_iter(m->private, *pos))
537 return NULL;
538 return p;
539}
540
541static void *s_start(struct seq_file *m, loff_t *pos)
542{
543 if (!update_iter(m->private, *pos))
544 return NULL;
545 return m->private;
546}
547
548static void s_stop(struct seq_file *m, void *p)
549{
550}
551
552static int s_show(struct seq_file *m, void *p)
553{
554 struct kallsym_iter *iter = m->private;
555
556 /* Some debugging symbols have no name. Ignore them. */
557 if (!iter->name[0])
558 return 0;
559
560 if (iter->module_name[0]) {
561 char type;
562
563 /*
564 * Label it "global" if it is exported,
565 * "local" if not exported.
566 */
567 type = iter->exported ? toupper(iter->type) :
568 tolower(iter->type);
569 seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
570 type, iter->name, iter->module_name);
571 } else
572 seq_printf(m, "%pK %c %s\n", (void *)iter->value,
573 iter->type, iter->name);
574 return 0;
575}
576
577static const struct seq_operations kallsyms_op = {
578 .start = s_start,
579 .next = s_next,
580 .stop = s_stop,
581 .show = s_show
582};
583
584static int kallsyms_open(struct inode *inode, struct file *file)
585{
586 /*
587 * We keep iterator in m->private, since normal case is to
588 * s_start from where we left off, so we avoid doing
589 * using get_symbol_offset for every symbol.
590 */
591 struct kallsym_iter *iter;
592 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
593 if (!iter)
594 return -ENOMEM;
595 reset_iter(iter, 0);
596
597 return 0;
598}
599
600#ifdef CONFIG_KGDB_KDB
601const char *kdb_walk_kallsyms(loff_t *pos)
602{
603 static struct kallsym_iter kdb_walk_kallsyms_iter;
604 if (*pos == 0) {
605 memset(&kdb_walk_kallsyms_iter, 0,
606 sizeof(kdb_walk_kallsyms_iter));
607 reset_iter(&kdb_walk_kallsyms_iter, 0);
608 }
609 while (1) {
610 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
611 return NULL;
612 ++*pos;
613 /* Some debugging symbols have no name. Ignore them. */
614 if (kdb_walk_kallsyms_iter.name[0])
615 return kdb_walk_kallsyms_iter.name;
616 }
617}
618#endif /* CONFIG_KGDB_KDB */
619
620static const struct file_operations kallsyms_operations = {
621 .open = kallsyms_open,
622 .read = seq_read,
623 .llseek = seq_lseek,
624 .release = seq_release_private,
625};
626
627static int __init kallsyms_init(void)
628{
629 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
630 return 0;
631}
632device_initcall(kallsyms_init);
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/kdb.h>
20#include <linux/err.h>
21#include <linux/proc_fs.h>
22#include <linux/sched.h> /* for cond_resched */
23#include <linux/mm.h>
24#include <linux/ctype.h>
25#include <linux/slab.h>
26
27#include <asm/sections.h>
28
29#ifdef CONFIG_KALLSYMS_ALL
30#define all_var 1
31#else
32#define all_var 0
33#endif
34
35/*
36 * These will be re-linked against their real values
37 * during the second link stage.
38 */
39extern const unsigned long kallsyms_addresses[] __attribute__((weak));
40extern const u8 kallsyms_names[] __attribute__((weak));
41
42/*
43 * Tell the compiler that the count isn't in the small data section if the arch
44 * has one (eg: FRV).
45 */
46extern const unsigned long kallsyms_num_syms
47__attribute__((weak, section(".rodata")));
48
49extern const u8 kallsyms_token_table[] __attribute__((weak));
50extern const u16 kallsyms_token_index[] __attribute__((weak));
51
52extern const unsigned long kallsyms_markers[] __attribute__((weak));
53
54static inline int is_kernel_inittext(unsigned long addr)
55{
56 if (addr >= (unsigned long)_sinittext
57 && addr <= (unsigned long)_einittext)
58 return 1;
59 return 0;
60}
61
62static inline int is_kernel_text(unsigned long addr)
63{
64 if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) ||
65 arch_is_kernel_text(addr))
66 return 1;
67 return in_gate_area_no_mm(addr);
68}
69
70static inline int is_kernel(unsigned long addr)
71{
72 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
73 return 1;
74 return in_gate_area_no_mm(addr);
75}
76
77static int is_ksym_addr(unsigned long addr)
78{
79 if (all_var)
80 return is_kernel(addr);
81
82 return is_kernel_text(addr) || is_kernel_inittext(addr);
83}
84
85/*
86 * Expand a compressed symbol data into the resulting uncompressed string,
87 * given the offset to where the symbol is in the compressed stream.
88 */
89static 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 /*
100 * Update the offset to return the offset for the next symbol on
101 * the compressed stream.
102 */
103 off += len + 1;
104
105 /*
106 * For every byte on the compressed symbol data, copy the table
107 * entry for that byte.
108 */
109 while (len) {
110 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
111 data++;
112 len--;
113
114 while (*tptr) {
115 if (skipped_first) {
116 *result = *tptr;
117 result++;
118 } else
119 skipped_first = 1;
120 tptr++;
121 }
122 }
123
124 *result = '\0';
125
126 /* Return to offset to the next symbol. */
127 return off;
128}
129
130/*
131 * Get symbol type information. This is encoded as a single char at the
132 * beginning of the symbol name.
133 */
134static char kallsyms_get_symbol_type(unsigned int off)
135{
136 /*
137 * Get just the first code, look it up in the token table,
138 * and return the first char from this token.
139 */
140 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
141}
142
143
144/*
145 * Find the offset on the compressed stream given and index in the
146 * kallsyms array.
147 */
148static unsigned int get_symbol_offset(unsigned long pos)
149{
150 const u8 *name;
151 int i;
152
153 /*
154 * Use the closest marker we have. We have markers every 256 positions,
155 * so that should be close enough.
156 */
157 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
158
159 /*
160 * Sequentially scan all the symbols up to the point we're searching
161 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
162 * so we just need to add the len to the current pointer for every
163 * symbol we wish to skip.
164 */
165 for (i = 0; i < (pos & 0xFF); i++)
166 name = name + (*name) + 1;
167
168 return name - kallsyms_names;
169}
170
171/* Lookup the address for this symbol. Returns 0 if not found. */
172unsigned long kallsyms_lookup_name(const char *name)
173{
174 char namebuf[KSYM_NAME_LEN];
175 unsigned long i;
176 unsigned int off;
177
178 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
179 off = kallsyms_expand_symbol(off, namebuf);
180
181 if (strcmp(namebuf, name) == 0)
182 return kallsyms_addresses[i];
183 }
184 return module_kallsyms_lookup_name(name);
185}
186EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
187
188int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
189 unsigned long),
190 void *data)
191{
192 char namebuf[KSYM_NAME_LEN];
193 unsigned long i;
194 unsigned int off;
195 int ret;
196
197 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
198 off = kallsyms_expand_symbol(off, namebuf);
199 ret = fn(data, namebuf, NULL, kallsyms_addresses[i]);
200 if (ret != 0)
201 return ret;
202 }
203 return module_kallsyms_on_each_symbol(fn, data);
204}
205EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
206
207static unsigned long get_symbol_pos(unsigned long addr,
208 unsigned long *symbolsize,
209 unsigned long *offset)
210{
211 unsigned long symbol_start = 0, symbol_end = 0;
212 unsigned long i, low, high, mid;
213
214 /* This kernel should never had been booted. */
215 BUG_ON(!kallsyms_addresses);
216
217 /* Do a binary search on the sorted kallsyms_addresses array. */
218 low = 0;
219 high = kallsyms_num_syms;
220
221 while (high - low > 1) {
222 mid = low + (high - low) / 2;
223 if (kallsyms_addresses[mid] <= addr)
224 low = mid;
225 else
226 high = mid;
227 }
228
229 /*
230 * Search for the first aliased symbol. Aliased
231 * symbols are symbols with the same address.
232 */
233 while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low])
234 --low;
235
236 symbol_start = kallsyms_addresses[low];
237
238 /* Search for next non-aliased symbol. */
239 for (i = low + 1; i < kallsyms_num_syms; i++) {
240 if (kallsyms_addresses[i] > symbol_start) {
241 symbol_end = kallsyms_addresses[i];
242 break;
243 }
244 }
245
246 /* If we found no next symbol, we use the end of the section. */
247 if (!symbol_end) {
248 if (is_kernel_inittext(addr))
249 symbol_end = (unsigned long)_einittext;
250 else if (all_var)
251 symbol_end = (unsigned long)_end;
252 else
253 symbol_end = (unsigned long)_etext;
254 }
255
256 if (symbolsize)
257 *symbolsize = symbol_end - symbol_start;
258 if (offset)
259 *offset = addr - symbol_start;
260
261 return low;
262}
263
264/*
265 * Lookup an address but don't bother to find any names.
266 */
267int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
268 unsigned long *offset)
269{
270 char namebuf[KSYM_NAME_LEN];
271 if (is_ksym_addr(addr))
272 return !!get_symbol_pos(addr, symbolsize, offset);
273
274 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
275}
276
277/*
278 * Lookup an address
279 * - modname is set to NULL if it's in the kernel.
280 * - We guarantee that the returned name is valid until we reschedule even if.
281 * It resides in a module.
282 * - We also guarantee that modname will be valid until rescheduled.
283 */
284const char *kallsyms_lookup(unsigned long addr,
285 unsigned long *symbolsize,
286 unsigned long *offset,
287 char **modname, char *namebuf)
288{
289 namebuf[KSYM_NAME_LEN - 1] = 0;
290 namebuf[0] = 0;
291
292 if (is_ksym_addr(addr)) {
293 unsigned long pos;
294
295 pos = get_symbol_pos(addr, symbolsize, offset);
296 /* Grab name */
297 kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);
298 if (modname)
299 *modname = NULL;
300 return namebuf;
301 }
302
303 /* See if it's in a module. */
304 return module_address_lookup(addr, symbolsize, offset, modname,
305 namebuf);
306}
307
308int lookup_symbol_name(unsigned long addr, char *symname)
309{
310 symname[0] = '\0';
311 symname[KSYM_NAME_LEN - 1] = '\0';
312
313 if (is_ksym_addr(addr)) {
314 unsigned long pos;
315
316 pos = get_symbol_pos(addr, NULL, NULL);
317 /* Grab name */
318 kallsyms_expand_symbol(get_symbol_offset(pos), symname);
319 return 0;
320 }
321 /* See if it's in a module. */
322 return lookup_module_symbol_name(addr, symname);
323}
324
325int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
326 unsigned long *offset, char *modname, char *name)
327{
328 name[0] = '\0';
329 name[KSYM_NAME_LEN - 1] = '\0';
330
331 if (is_ksym_addr(addr)) {
332 unsigned long pos;
333
334 pos = get_symbol_pos(addr, size, offset);
335 /* Grab name */
336 kallsyms_expand_symbol(get_symbol_offset(pos), name);
337 modname[0] = '\0';
338 return 0;
339 }
340 /* See if it's in a module. */
341 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
342}
343
344/* Look up a kernel symbol and return it in a text buffer. */
345static int __sprint_symbol(char *buffer, unsigned long address,
346 int symbol_offset)
347{
348 char *modname;
349 const char *name;
350 unsigned long offset, size;
351 int len;
352
353 address += symbol_offset;
354 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
355 if (!name)
356 return sprintf(buffer, "0x%lx", address);
357
358 if (name != buffer)
359 strcpy(buffer, name);
360 len = strlen(buffer);
361 buffer += len;
362 offset -= symbol_offset;
363
364 if (modname)
365 len += sprintf(buffer, "+%#lx/%#lx [%s]", offset, size, modname);
366 else
367 len += sprintf(buffer, "+%#lx/%#lx", offset, size);
368
369 return len;
370}
371
372/**
373 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
374 * @buffer: buffer to be stored
375 * @address: address to lookup
376 *
377 * This function looks up a kernel symbol with @address and stores its name,
378 * offset, size and module name to @buffer if possible. If no symbol was found,
379 * just saves its @address as is.
380 *
381 * This function returns the number of bytes stored in @buffer.
382 */
383int sprint_symbol(char *buffer, unsigned long address)
384{
385 return __sprint_symbol(buffer, address, 0);
386}
387
388EXPORT_SYMBOL_GPL(sprint_symbol);
389
390/**
391 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
392 * @buffer: buffer to be stored
393 * @address: address to lookup
394 *
395 * This function is for stack backtrace and does the same thing as
396 * sprint_symbol() but with modified/decreased @address. If there is a
397 * tail-call to the function marked "noreturn", gcc optimized out code after
398 * the call so that the stack-saved return address could point outside of the
399 * caller. This function ensures that kallsyms will find the original caller
400 * by decreasing @address.
401 *
402 * This function returns the number of bytes stored in @buffer.
403 */
404int sprint_backtrace(char *buffer, unsigned long address)
405{
406 return __sprint_symbol(buffer, address, -1);
407}
408
409/* Look up a kernel symbol and print it to the kernel messages. */
410void __print_symbol(const char *fmt, unsigned long address)
411{
412 char buffer[KSYM_SYMBOL_LEN];
413
414 sprint_symbol(buffer, address);
415
416 printk(fmt, buffer);
417}
418EXPORT_SYMBOL(__print_symbol);
419
420/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
421struct kallsym_iter {
422 loff_t pos;
423 unsigned long value;
424 unsigned int nameoff; /* If iterating in core kernel symbols. */
425 char type;
426 char name[KSYM_NAME_LEN];
427 char module_name[MODULE_NAME_LEN];
428 int exported;
429};
430
431static int get_ksymbol_mod(struct kallsym_iter *iter)
432{
433 if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
434 &iter->type, iter->name, iter->module_name,
435 &iter->exported) < 0)
436 return 0;
437 return 1;
438}
439
440/* Returns space to next name. */
441static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
442{
443 unsigned off = iter->nameoff;
444
445 iter->module_name[0] = '\0';
446 iter->value = kallsyms_addresses[iter->pos];
447
448 iter->type = kallsyms_get_symbol_type(off);
449
450 off = kallsyms_expand_symbol(off, iter->name);
451
452 return off - iter->nameoff;
453}
454
455static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
456{
457 iter->name[0] = '\0';
458 iter->nameoff = get_symbol_offset(new_pos);
459 iter->pos = new_pos;
460}
461
462/* Returns false if pos at or past end of file. */
463static int update_iter(struct kallsym_iter *iter, loff_t pos)
464{
465 /* Module symbols can be accessed randomly. */
466 if (pos >= kallsyms_num_syms) {
467 iter->pos = pos;
468 return get_ksymbol_mod(iter);
469 }
470
471 /* If we're not on the desired position, reset to new position. */
472 if (pos != iter->pos)
473 reset_iter(iter, pos);
474
475 iter->nameoff += get_ksymbol_core(iter);
476 iter->pos++;
477
478 return 1;
479}
480
481static void *s_next(struct seq_file *m, void *p, loff_t *pos)
482{
483 (*pos)++;
484
485 if (!update_iter(m->private, *pos))
486 return NULL;
487 return p;
488}
489
490static void *s_start(struct seq_file *m, loff_t *pos)
491{
492 if (!update_iter(m->private, *pos))
493 return NULL;
494 return m->private;
495}
496
497static void s_stop(struct seq_file *m, void *p)
498{
499}
500
501static int s_show(struct seq_file *m, void *p)
502{
503 struct kallsym_iter *iter = m->private;
504
505 /* Some debugging symbols have no name. Ignore them. */
506 if (!iter->name[0])
507 return 0;
508
509 if (iter->module_name[0]) {
510 char type;
511
512 /*
513 * Label it "global" if it is exported,
514 * "local" if not exported.
515 */
516 type = iter->exported ? toupper(iter->type) :
517 tolower(iter->type);
518 seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
519 type, iter->name, iter->module_name);
520 } else
521 seq_printf(m, "%pK %c %s\n", (void *)iter->value,
522 iter->type, iter->name);
523 return 0;
524}
525
526static const struct seq_operations kallsyms_op = {
527 .start = s_start,
528 .next = s_next,
529 .stop = s_stop,
530 .show = s_show
531};
532
533static int kallsyms_open(struct inode *inode, struct file *file)
534{
535 /*
536 * We keep iterator in m->private, since normal case is to
537 * s_start from where we left off, so we avoid doing
538 * using get_symbol_offset for every symbol.
539 */
540 struct kallsym_iter *iter;
541 int ret;
542
543 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
544 if (!iter)
545 return -ENOMEM;
546 reset_iter(iter, 0);
547
548 ret = seq_open(file, &kallsyms_op);
549 if (ret == 0)
550 ((struct seq_file *)file->private_data)->private = iter;
551 else
552 kfree(iter);
553 return ret;
554}
555
556#ifdef CONFIG_KGDB_KDB
557const char *kdb_walk_kallsyms(loff_t *pos)
558{
559 static struct kallsym_iter kdb_walk_kallsyms_iter;
560 if (*pos == 0) {
561 memset(&kdb_walk_kallsyms_iter, 0,
562 sizeof(kdb_walk_kallsyms_iter));
563 reset_iter(&kdb_walk_kallsyms_iter, 0);
564 }
565 while (1) {
566 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
567 return NULL;
568 ++*pos;
569 /* Some debugging symbols have no name. Ignore them. */
570 if (kdb_walk_kallsyms_iter.name[0])
571 return kdb_walk_kallsyms_iter.name;
572 }
573}
574#endif /* CONFIG_KGDB_KDB */
575
576static const struct file_operations kallsyms_operations = {
577 .open = kallsyms_open,
578 .read = seq_read,
579 .llseek = seq_lseek,
580 .release = seq_release_private,
581};
582
583static int __init kallsyms_init(void)
584{
585 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
586 return 0;
587}
588device_initcall(kallsyms_init);