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CommitLineData
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>
67fc4e0c 19#include <linux/kdb.h>
1da177e4
LT
20#include <linux/err.h>
21#include <linux/proc_fs.h>
4e57b681 22#include <linux/sched.h> /* for cond_resched */
1da177e4 23#include <linux/mm.h>
07354a00 24#include <linux/ctype.h>
5a0e3ad6 25#include <linux/slab.h>
74451e66 26#include <linux/filter.h>
aba4b5c2 27#include <linux/ftrace.h>
52f5684c 28#include <linux/compiler.h>
1da177e4
LT
29
30#include <asm/sections.h>
31
ad6ccfad
MK
32/*
33 * These will be re-linked against their real values
34 * during the second link stage.
35 */
52f5684c 36extern const unsigned long kallsyms_addresses[] __weak;
2213e9a6 37extern const int kallsyms_offsets[] __weak;
52f5684c 38extern const u8 kallsyms_names[] __weak;
1da177e4 39
ad6ccfad
MK
40/*
41 * Tell the compiler that the count isn't in the small data section if the arch
42 * has one (eg: FRV).
9e6c1e63
DH
43 */
44extern const unsigned long kallsyms_num_syms
2ea03891 45__attribute__((weak, section(".rodata")));
9e6c1e63 46
2213e9a6
AB
47extern const unsigned long kallsyms_relative_base
48__attribute__((weak, section(".rodata")));
49
52f5684c
GID
50extern const u8 kallsyms_token_table[] __weak;
51extern const u16 kallsyms_token_index[] __weak;
1da177e4 52
52f5684c 53extern const unsigned long kallsyms_markers[] __weak;
1da177e4
LT
54
55static inline int is_kernel_inittext(unsigned long addr)
56{
57 if (addr >= (unsigned long)_sinittext
58 && addr <= (unsigned long)_einittext)
59 return 1;
60 return 0;
61}
62
63static inline int is_kernel_text(unsigned long addr)
64{
128e8db3
MF
65 if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) ||
66 arch_is_kernel_text(addr))
1da177e4 67 return 1;
cae5d390 68 return in_gate_area_no_mm(addr);
1da177e4
LT
69}
70
71static inline int is_kernel(unsigned long addr)
72{
73 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
74 return 1;
cae5d390 75 return in_gate_area_no_mm(addr);
1da177e4
LT
76}
77
ffc50891
FBH
78static int is_ksym_addr(unsigned long addr)
79{
63b23e2c 80 if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
ffc50891
FBH
81 return is_kernel(addr);
82
a3b81113 83 return is_kernel_text(addr) || is_kernel_inittext(addr);
ffc50891
FBH
84}
85
ad6ccfad
MK
86/*
87 * Expand a compressed symbol data into the resulting uncompressed string,
e3f26752 88 * if uncompressed string is too long (>= maxlen), it will be truncated,
ad6ccfad
MK
89 * given the offset to where the symbol is in the compressed stream.
90 */
e3f26752
CG
91static unsigned int kallsyms_expand_symbol(unsigned int off,
92 char *result, size_t maxlen)
1da177e4
LT
93{
94 int len, skipped_first = 0;
aad09470 95 const u8 *tptr, *data;
1da177e4 96
ad6ccfad 97 /* Get the compressed symbol length from the first symbol byte. */
1da177e4
LT
98 data = &kallsyms_names[off];
99 len = *data;
100 data++;
101
ad6ccfad
MK
102 /*
103 * Update the offset to return the offset for the next symbol on
104 * the compressed stream.
105 */
1da177e4
LT
106 off += len + 1;
107
ad6ccfad
MK
108 /*
109 * For every byte on the compressed symbol data, copy the table
110 * entry for that byte.
111 */
112 while (len) {
113 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
1da177e4
LT
114 data++;
115 len--;
116
117 while (*tptr) {
ad6ccfad 118 if (skipped_first) {
e3f26752
CG
119 if (maxlen <= 1)
120 goto tail;
1da177e4
LT
121 *result = *tptr;
122 result++;
e3f26752 123 maxlen--;
1da177e4
LT
124 } else
125 skipped_first = 1;
126 tptr++;
127 }
128 }
129
e3f26752
CG
130tail:
131 if (maxlen)
132 *result = '\0';
1da177e4 133
ad6ccfad 134 /* Return to offset to the next symbol. */
1da177e4
LT
135 return off;
136}
137
ad6ccfad
MK
138/*
139 * Get symbol type information. This is encoded as a single char at the
140 * beginning of the symbol name.
141 */
1da177e4
LT
142static char kallsyms_get_symbol_type(unsigned int off)
143{
ad6ccfad
MK
144 /*
145 * Get just the first code, look it up in the token table,
146 * and return the first char from this token.
147 */
148 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
1da177e4
LT
149}
150
151
ad6ccfad
MK
152/*
153 * Find the offset on the compressed stream given and index in the
154 * kallsyms array.
155 */
1da177e4
LT
156static unsigned int get_symbol_offset(unsigned long pos)
157{
aad09470 158 const u8 *name;
1da177e4
LT
159 int i;
160
ad6ccfad
MK
161 /*
162 * Use the closest marker we have. We have markers every 256 positions,
163 * so that should be close enough.
164 */
165 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
1da177e4 166
ad6ccfad
MK
167 /*
168 * Sequentially scan all the symbols up to the point we're searching
169 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
170 * so we just need to add the len to the current pointer for every
171 * symbol we wish to skip.
172 */
173 for (i = 0; i < (pos & 0xFF); i++)
1da177e4
LT
174 name = name + (*name) + 1;
175
176 return name - kallsyms_names;
177}
178
2213e9a6
AB
179static unsigned long kallsyms_sym_address(int idx)
180{
181 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
182 return kallsyms_addresses[idx];
183
184 /* values are unsigned offsets if --absolute-percpu is not in effect */
185 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
186 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
187
188 /* ...otherwise, positive offsets are absolute values */
189 if (kallsyms_offsets[idx] >= 0)
190 return kallsyms_offsets[idx];
191
192 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
193 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
194}
195
1da177e4
LT
196/* Lookup the address for this symbol. Returns 0 if not found. */
197unsigned long kallsyms_lookup_name(const char *name)
198{
9281acea 199 char namebuf[KSYM_NAME_LEN];
1da177e4
LT
200 unsigned long i;
201 unsigned int off;
202
203 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
e3f26752 204 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
1da177e4
LT
205
206 if (strcmp(namebuf, name) == 0)
2213e9a6 207 return kallsyms_sym_address(i);
1da177e4
LT
208 }
209 return module_kallsyms_lookup_name(name);
210}
f60d24d2 211EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
1da177e4 212
75a66614
AK
213int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
214 unsigned long),
215 void *data)
216{
217 char namebuf[KSYM_NAME_LEN];
218 unsigned long i;
219 unsigned int off;
220 int ret;
221
222 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
e3f26752 223 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
2213e9a6 224 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
75a66614
AK
225 if (ret != 0)
226 return ret;
227 }
228 return module_kallsyms_on_each_symbol(fn, data);
229}
230EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
231
ffc50891
FBH
232static unsigned long get_symbol_pos(unsigned long addr,
233 unsigned long *symbolsize,
234 unsigned long *offset)
235{
236 unsigned long symbol_start = 0, symbol_end = 0;
237 unsigned long i, low, high, mid;
238
2ea03891 239 /* This kernel should never had been booted. */
2213e9a6
AB
240 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
241 BUG_ON(!kallsyms_addresses);
242 else
243 BUG_ON(!kallsyms_offsets);
2ea03891 244
ad6ccfad 245 /* Do a binary search on the sorted kallsyms_addresses array. */
ffc50891
FBH
246 low = 0;
247 high = kallsyms_num_syms;
248
249 while (high - low > 1) {
2fc9c4e1 250 mid = low + (high - low) / 2;
2213e9a6 251 if (kallsyms_sym_address(mid) <= addr)
ffc50891
FBH
252 low = mid;
253 else
254 high = mid;
255 }
256
257 /*
ad6ccfad
MK
258 * Search for the first aliased symbol. Aliased
259 * symbols are symbols with the same address.
ffc50891 260 */
2213e9a6 261 while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
ffc50891
FBH
262 --low;
263
2213e9a6 264 symbol_start = kallsyms_sym_address(low);
ffc50891 265
ad6ccfad 266 /* Search for next non-aliased symbol. */
ffc50891 267 for (i = low + 1; i < kallsyms_num_syms; i++) {
2213e9a6
AB
268 if (kallsyms_sym_address(i) > symbol_start) {
269 symbol_end = kallsyms_sym_address(i);
ffc50891
FBH
270 break;
271 }
272 }
273
ad6ccfad 274 /* If we found no next symbol, we use the end of the section. */
ffc50891
FBH
275 if (!symbol_end) {
276 if (is_kernel_inittext(addr))
277 symbol_end = (unsigned long)_einittext;
63b23e2c 278 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
ffc50891
FBH
279 symbol_end = (unsigned long)_end;
280 else
281 symbol_end = (unsigned long)_etext;
282 }
283
ffb45122
AD
284 if (symbolsize)
285 *symbolsize = symbol_end - symbol_start;
286 if (offset)
287 *offset = addr - symbol_start;
ffc50891
FBH
288
289 return low;
290}
291
292/*
293 * Lookup an address but don't bother to find any names.
294 */
295int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
296 unsigned long *offset)
297{
6dd06c9f 298 char namebuf[KSYM_NAME_LEN];
74451e66 299
ffc50891
FBH
300 if (is_ksym_addr(addr))
301 return !!get_symbol_pos(addr, symbolsize, offset);
74451e66
DB
302 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) ||
303 !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
ffc50891
FBH
304}
305
1da177e4
LT
306/*
307 * Lookup an address
ad6ccfad
MK
308 * - modname is set to NULL if it's in the kernel.
309 * - We guarantee that the returned name is valid until we reschedule even if.
310 * It resides in a module.
311 * - We also guarantee that modname will be valid until rescheduled.
1da177e4
LT
312 */
313const char *kallsyms_lookup(unsigned long addr,
314 unsigned long *symbolsize,
315 unsigned long *offset,
316 char **modname, char *namebuf)
317{
74451e66
DB
318 const char *ret;
319
9281acea 320 namebuf[KSYM_NAME_LEN - 1] = 0;
1da177e4
LT
321 namebuf[0] = 0;
322
ffc50891
FBH
323 if (is_ksym_addr(addr)) {
324 unsigned long pos;
1da177e4 325
ffc50891 326 pos = get_symbol_pos(addr, symbolsize, offset);
1da177e4 327 /* Grab name */
e3f26752
CG
328 kallsyms_expand_symbol(get_symbol_offset(pos),
329 namebuf, KSYM_NAME_LEN);
7a74fc49
KM
330 if (modname)
331 *modname = NULL;
1da177e4
LT
332 return namebuf;
333 }
334
74451e66
DB
335 /* See if it's in a module or a BPF JITed image. */
336 ret = module_address_lookup(addr, symbolsize, offset,
337 modname, namebuf);
338 if (!ret)
339 ret = bpf_address_lookup(addr, symbolsize,
340 offset, modname, namebuf);
aba4b5c2
SRV
341
342 if (!ret)
343 ret = ftrace_mod_address_lookup(addr, symbolsize,
344 offset, modname, namebuf);
74451e66 345 return ret;
1da177e4
LT
346}
347
9d65cb4a
AD
348int lookup_symbol_name(unsigned long addr, char *symname)
349{
350 symname[0] = '\0';
9281acea 351 symname[KSYM_NAME_LEN - 1] = '\0';
9d65cb4a
AD
352
353 if (is_ksym_addr(addr)) {
354 unsigned long pos;
355
356 pos = get_symbol_pos(addr, NULL, NULL);
357 /* Grab name */
e3f26752
CG
358 kallsyms_expand_symbol(get_symbol_offset(pos),
359 symname, KSYM_NAME_LEN);
9d65cb4a
AD
360 return 0;
361 }
ad6ccfad 362 /* See if it's in a module. */
9d65cb4a
AD
363 return lookup_module_symbol_name(addr, symname);
364}
365
a5c43dae
AD
366int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
367 unsigned long *offset, char *modname, char *name)
368{
369 name[0] = '\0';
9281acea 370 name[KSYM_NAME_LEN - 1] = '\0';
a5c43dae
AD
371
372 if (is_ksym_addr(addr)) {
373 unsigned long pos;
374
375 pos = get_symbol_pos(addr, size, offset);
376 /* Grab name */
e3f26752
CG
377 kallsyms_expand_symbol(get_symbol_offset(pos),
378 name, KSYM_NAME_LEN);
a5c43dae
AD
379 modname[0] = '\0';
380 return 0;
381 }
ad6ccfad 382 /* See if it's in a module. */
a5c43dae
AD
383 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
384}
385
42e38083 386/* Look up a kernel symbol and return it in a text buffer. */
0f77a8d3 387static int __sprint_symbol(char *buffer, unsigned long address,
4796dd20 388 int symbol_offset, int add_offset)
1da177e4
LT
389{
390 char *modname;
391 const char *name;
392 unsigned long offset, size;
966c8c12 393 int len;
1da177e4 394
0f77a8d3 395 address += symbol_offset;
966c8c12 396 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
1da177e4 397 if (!name)
b86280aa 398 return sprintf(buffer, "0x%lx", address - symbol_offset);
19769b76 399
966c8c12
HD
400 if (name != buffer)
401 strcpy(buffer, name);
402 len = strlen(buffer);
0f77a8d3 403 offset -= symbol_offset;
966c8c12 404
4796dd20
SB
405 if (add_offset)
406 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
407
19769b76 408 if (modname)
4796dd20 409 len += sprintf(buffer + len, " [%s]", modname);
966c8c12
HD
410
411 return len;
42e38083 412}
0f77a8d3
NK
413
414/**
415 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
416 * @buffer: buffer to be stored
417 * @address: address to lookup
418 *
419 * This function looks up a kernel symbol with @address and stores its name,
420 * offset, size and module name to @buffer if possible. If no symbol was found,
421 * just saves its @address as is.
422 *
423 * This function returns the number of bytes stored in @buffer.
424 */
425int sprint_symbol(char *buffer, unsigned long address)
426{
4796dd20 427 return __sprint_symbol(buffer, address, 0, 1);
0f77a8d3 428}
ad6ccfad 429EXPORT_SYMBOL_GPL(sprint_symbol);
42e38083 430
4796dd20
SB
431/**
432 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
433 * @buffer: buffer to be stored
434 * @address: address to lookup
435 *
436 * This function looks up a kernel symbol with @address and stores its name
437 * and module name to @buffer if possible. If no symbol was found, just saves
438 * its @address as is.
439 *
440 * This function returns the number of bytes stored in @buffer.
441 */
442int sprint_symbol_no_offset(char *buffer, unsigned long address)
443{
444 return __sprint_symbol(buffer, address, 0, 0);
445}
446EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
447
0f77a8d3
NK
448/**
449 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
450 * @buffer: buffer to be stored
451 * @address: address to lookup
452 *
453 * This function is for stack backtrace and does the same thing as
454 * sprint_symbol() but with modified/decreased @address. If there is a
455 * tail-call to the function marked "noreturn", gcc optimized out code after
456 * the call so that the stack-saved return address could point outside of the
457 * caller. This function ensures that kallsyms will find the original caller
458 * by decreasing @address.
459 *
460 * This function returns the number of bytes stored in @buffer.
461 */
462int sprint_backtrace(char *buffer, unsigned long address)
463{
4796dd20 464 return __sprint_symbol(buffer, address, -1, 1);
0f77a8d3
NK
465}
466
42e38083
RP
467/* Look up a kernel symbol and print it to the kernel messages. */
468void __print_symbol(const char *fmt, unsigned long address)
469{
470 char buffer[KSYM_SYMBOL_LEN];
471
472 sprint_symbol(buffer, address);
473
1da177e4
LT
474 printk(fmt, buffer);
475}
ad6ccfad 476EXPORT_SYMBOL(__print_symbol);
1da177e4
LT
477
478/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
ad6ccfad 479struct kallsym_iter {
1da177e4 480 loff_t pos;
74451e66 481 loff_t pos_mod_end;
6171a031 482 loff_t pos_ftrace_mod_end;
1da177e4 483 unsigned long value;
ad6ccfad 484 unsigned int nameoff; /* If iterating in core kernel symbols. */
1da177e4 485 char type;
9281acea
TH
486 char name[KSYM_NAME_LEN];
487 char module_name[MODULE_NAME_LEN];
ea07890a 488 int exported;
c0f3ea15 489 int show_value;
1da177e4
LT
490};
491
1da177e4
LT
492static int get_ksymbol_mod(struct kallsym_iter *iter)
493{
74451e66
DB
494 int ret = module_get_kallsym(iter->pos - kallsyms_num_syms,
495 &iter->value, &iter->type,
496 iter->name, iter->module_name,
497 &iter->exported);
498 if (ret < 0) {
499 iter->pos_mod_end = iter->pos;
1da177e4 500 return 0;
74451e66
DB
501 }
502
1da177e4
LT
503 return 1;
504}
505
6171a031
SRV
506static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
507{
508 int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
509 &iter->value, &iter->type,
510 iter->name, iter->module_name,
511 &iter->exported);
512 if (ret < 0) {
513 iter->pos_ftrace_mod_end = iter->pos;
514 return 0;
515 }
516
517 return 1;
518}
519
74451e66
DB
520static int get_ksymbol_bpf(struct kallsym_iter *iter)
521{
522 iter->module_name[0] = '\0';
523 iter->exported = 0;
6171a031 524 return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
74451e66
DB
525 &iter->value, &iter->type,
526 iter->name) < 0 ? 0 : 1;
527}
528
1da177e4
LT
529/* Returns space to next name. */
530static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
531{
532 unsigned off = iter->nameoff;
533
ea07890a 534 iter->module_name[0] = '\0';
2213e9a6 535 iter->value = kallsyms_sym_address(iter->pos);
1da177e4
LT
536
537 iter->type = kallsyms_get_symbol_type(off);
538
e3f26752 539 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
1da177e4
LT
540
541 return off - iter->nameoff;
542}
543
544static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
545{
546 iter->name[0] = '\0';
547 iter->nameoff = get_symbol_offset(new_pos);
548 iter->pos = new_pos;
6171a031 549 if (new_pos == 0) {
74451e66 550 iter->pos_mod_end = 0;
6171a031
SRV
551 iter->pos_ftrace_mod_end = 0;
552 }
74451e66
DB
553}
554
555static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
556{
557 iter->pos = pos;
558
6171a031
SRV
559 if (iter->pos_ftrace_mod_end > 0 &&
560 iter->pos_ftrace_mod_end < iter->pos)
74451e66
DB
561 return get_ksymbol_bpf(iter);
562
6171a031
SRV
563 if (iter->pos_mod_end > 0 &&
564 iter->pos_mod_end < iter->pos) {
565 if (!get_ksymbol_ftrace_mod(iter))
566 return get_ksymbol_bpf(iter);
567 return 1;
568 }
569
570 if (!get_ksymbol_mod(iter)) {
571 if (!get_ksymbol_ftrace_mod(iter))
572 return get_ksymbol_bpf(iter);
573 }
74451e66
DB
574
575 return 1;
1da177e4
LT
576}
577
578/* Returns false if pos at or past end of file. */
579static int update_iter(struct kallsym_iter *iter, loff_t pos)
580{
581 /* Module symbols can be accessed randomly. */
74451e66
DB
582 if (pos >= kallsyms_num_syms)
583 return update_iter_mod(iter, pos);
ad6ccfad 584
1da177e4
LT
585 /* If we're not on the desired position, reset to new position. */
586 if (pos != iter->pos)
587 reset_iter(iter, pos);
588
589 iter->nameoff += get_ksymbol_core(iter);
590 iter->pos++;
591
592 return 1;
593}
594
595static void *s_next(struct seq_file *m, void *p, loff_t *pos)
596{
597 (*pos)++;
598
599 if (!update_iter(m->private, *pos))
600 return NULL;
601 return p;
602}
603
604static void *s_start(struct seq_file *m, loff_t *pos)
605{
606 if (!update_iter(m->private, *pos))
607 return NULL;
608 return m->private;
609}
610
611static void s_stop(struct seq_file *m, void *p)
612{
613}
614
615static int s_show(struct seq_file *m, void *p)
616{
668533dc 617 void *value;
1da177e4
LT
618 struct kallsym_iter *iter = m->private;
619
ad6ccfad 620 /* Some debugging symbols have no name. Ignore them. */
1da177e4
LT
621 if (!iter->name[0])
622 return 0;
623
668533dc 624 value = iter->show_value ? (void *)iter->value : NULL;
c0f3ea15 625
ea07890a
AD
626 if (iter->module_name[0]) {
627 char type;
628
ad6ccfad
MK
629 /*
630 * Label it "global" if it is exported,
631 * "local" if not exported.
632 */
ea07890a
AD
633 type = iter->exported ? toupper(iter->type) :
634 tolower(iter->type);
668533dc 635 seq_printf(m, "%px %c %s\t[%s]\n", value,
9f36e2c4 636 type, iter->name, iter->module_name);
ea07890a 637 } else
668533dc 638 seq_printf(m, "%px %c %s\n", value,
9f36e2c4 639 iter->type, iter->name);
1da177e4
LT
640 return 0;
641}
642
15ad7cdc 643static const struct seq_operations kallsyms_op = {
1da177e4
LT
644 .start = s_start,
645 .next = s_next,
646 .stop = s_stop,
647 .show = s_show
648};
649
c0f3ea15
LT
650static inline int kallsyms_for_perf(void)
651{
652#ifdef CONFIG_PERF_EVENTS
653 extern int sysctl_perf_event_paranoid;
654 if (sysctl_perf_event_paranoid <= 1)
655 return 1;
656#endif
657 return 0;
658}
659
660/*
661 * We show kallsyms information even to normal users if we've enabled
662 * kernel profiling and are explicitly not paranoid (so kptr_restrict
663 * is clear, and sysctl_perf_event_paranoid isn't set).
664 *
665 * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
666 * block even that).
667 */
516fb7f2 668int kallsyms_show_value(void)
c0f3ea15
LT
669{
670 switch (kptr_restrict) {
671 case 0:
672 if (kallsyms_for_perf())
673 return 1;
674 /* fallthrough */
675 case 1:
676 if (has_capability_noaudit(current, CAP_SYSLOG))
677 return 1;
678 /* fallthrough */
679 default:
680 return 0;
681 }
682}
683
1da177e4
LT
684static int kallsyms_open(struct inode *inode, struct file *file)
685{
ad6ccfad
MK
686 /*
687 * We keep iterator in m->private, since normal case is to
1da177e4 688 * s_start from where we left off, so we avoid doing
ad6ccfad
MK
689 * using get_symbol_offset for every symbol.
690 */
1da177e4 691 struct kallsym_iter *iter;
0049f26a 692 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
1da177e4
LT
693 if (!iter)
694 return -ENOMEM;
695 reset_iter(iter, 0);
696
c0f3ea15 697 iter->show_value = kallsyms_show_value();
0049f26a 698 return 0;
1da177e4
LT
699}
700
67fc4e0c
JW
701#ifdef CONFIG_KGDB_KDB
702const char *kdb_walk_kallsyms(loff_t *pos)
703{
704 static struct kallsym_iter kdb_walk_kallsyms_iter;
705 if (*pos == 0) {
706 memset(&kdb_walk_kallsyms_iter, 0,
707 sizeof(kdb_walk_kallsyms_iter));
708 reset_iter(&kdb_walk_kallsyms_iter, 0);
709 }
710 while (1) {
711 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
712 return NULL;
713 ++*pos;
714 /* Some debugging symbols have no name. Ignore them. */
715 if (kdb_walk_kallsyms_iter.name[0])
716 return kdb_walk_kallsyms_iter.name;
717 }
718}
719#endif /* CONFIG_KGDB_KDB */
720
15ad7cdc 721static const struct file_operations kallsyms_operations = {
1da177e4
LT
722 .open = kallsyms_open,
723 .read = seq_read,
724 .llseek = seq_lseek,
5a0c6a0d 725 .release = seq_release_private,
1da177e4
LT
726};
727
728static int __init kallsyms_init(void)
729{
33e0d57f 730 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
1da177e4
LT
731 return 0;
732}
ad6ccfad 733device_initcall(kallsyms_init);