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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
4 *
5 * Rewritten and vastly simplified by Rusty Russell for in-kernel
6 * module loader:
7 * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
8 *
9 * ChangeLog:
10 *
11 * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
12 * Changed the compression method from stem compression to "table lookup"
13 * compression (see scripts/kallsyms.c for a more complete description)
14 */
15#include <linux/kallsyms.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/ctype.h>
24#include <linux/slab.h>
25#include <linux/filter.h>
26#include <linux/ftrace.h>
27#include <linux/compiler.h>
28
29/*
30 * These will be re-linked against their real values
31 * during the second link stage.
32 */
33extern const unsigned long kallsyms_addresses[] __weak;
34extern const int kallsyms_offsets[] __weak;
35extern const u8 kallsyms_names[] __weak;
36
37/*
38 * Tell the compiler that the count isn't in the small data section if the arch
39 * has one (eg: FRV).
40 */
41extern const unsigned int kallsyms_num_syms
42__attribute__((weak, section(".rodata")));
43
44extern const unsigned long kallsyms_relative_base
45__attribute__((weak, section(".rodata")));
46
47extern const u8 kallsyms_token_table[] __weak;
48extern const u16 kallsyms_token_index[] __weak;
49
50extern const unsigned int kallsyms_markers[] __weak;
51
52/*
53 * Expand a compressed symbol data into the resulting uncompressed string,
54 * if uncompressed string is too long (>= maxlen), it will be truncated,
55 * given the offset to where the symbol is in the compressed stream.
56 */
57static unsigned int kallsyms_expand_symbol(unsigned int off,
58 char *result, size_t maxlen)
59{
60 int len, skipped_first = 0;
61 const u8 *tptr, *data;
62
63 /* Get the compressed symbol length from the first symbol byte. */
64 data = &kallsyms_names[off];
65 len = *data;
66 data++;
67
68 /*
69 * Update the offset to return the offset for the next symbol on
70 * the compressed stream.
71 */
72 off += len + 1;
73
74 /*
75 * For every byte on the compressed symbol data, copy the table
76 * entry for that byte.
77 */
78 while (len) {
79 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
80 data++;
81 len--;
82
83 while (*tptr) {
84 if (skipped_first) {
85 if (maxlen <= 1)
86 goto tail;
87 *result = *tptr;
88 result++;
89 maxlen--;
90 } else
91 skipped_first = 1;
92 tptr++;
93 }
94 }
95
96tail:
97 if (maxlen)
98 *result = '\0';
99
100 /* Return to offset to the next symbol. */
101 return off;
102}
103
104/*
105 * Get symbol type information. This is encoded as a single char at the
106 * beginning of the symbol name.
107 */
108static char kallsyms_get_symbol_type(unsigned int off)
109{
110 /*
111 * Get just the first code, look it up in the token table,
112 * and return the first char from this token.
113 */
114 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
115}
116
117
118/*
119 * Find the offset on the compressed stream given and index in the
120 * kallsyms array.
121 */
122static unsigned int get_symbol_offset(unsigned long pos)
123{
124 const u8 *name;
125 int i;
126
127 /*
128 * Use the closest marker we have. We have markers every 256 positions,
129 * so that should be close enough.
130 */
131 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
132
133 /*
134 * Sequentially scan all the symbols up to the point we're searching
135 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
136 * so we just need to add the len to the current pointer for every
137 * symbol we wish to skip.
138 */
139 for (i = 0; i < (pos & 0xFF); i++)
140 name = name + (*name) + 1;
141
142 return name - kallsyms_names;
143}
144
145static unsigned long kallsyms_sym_address(int idx)
146{
147 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
148 return kallsyms_addresses[idx];
149
150 /* values are unsigned offsets if --absolute-percpu is not in effect */
151 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
152 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
153
154 /* ...otherwise, positive offsets are absolute values */
155 if (kallsyms_offsets[idx] >= 0)
156 return kallsyms_offsets[idx];
157
158 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
159 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
160}
161
162/* Lookup the address for this symbol. Returns 0 if not found. */
163unsigned long kallsyms_lookup_name(const char *name)
164{
165 char namebuf[KSYM_NAME_LEN];
166 unsigned long i;
167 unsigned int off;
168
169 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
170 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
171
172 if (strcmp(namebuf, name) == 0)
173 return kallsyms_sym_address(i);
174 }
175 return module_kallsyms_lookup_name(name);
176}
177EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
178
179int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
180 unsigned long),
181 void *data)
182{
183 char namebuf[KSYM_NAME_LEN];
184 unsigned long i;
185 unsigned int off;
186 int ret;
187
188 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
189 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
190 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
191 if (ret != 0)
192 return ret;
193 }
194 return module_kallsyms_on_each_symbol(fn, data);
195}
196EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
197
198static unsigned long get_symbol_pos(unsigned long addr,
199 unsigned long *symbolsize,
200 unsigned long *offset)
201{
202 unsigned long symbol_start = 0, symbol_end = 0;
203 unsigned long i, low, high, mid;
204
205 /* This kernel should never had been booted. */
206 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
207 BUG_ON(!kallsyms_addresses);
208 else
209 BUG_ON(!kallsyms_offsets);
210
211 /* Do a binary search on the sorted kallsyms_addresses array. */
212 low = 0;
213 high = kallsyms_num_syms;
214
215 while (high - low > 1) {
216 mid = low + (high - low) / 2;
217 if (kallsyms_sym_address(mid) <= addr)
218 low = mid;
219 else
220 high = mid;
221 }
222
223 /*
224 * Search for the first aliased symbol. Aliased
225 * symbols are symbols with the same address.
226 */
227 while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
228 --low;
229
230 symbol_start = kallsyms_sym_address(low);
231
232 /* Search for next non-aliased symbol. */
233 for (i = low + 1; i < kallsyms_num_syms; i++) {
234 if (kallsyms_sym_address(i) > symbol_start) {
235 symbol_end = kallsyms_sym_address(i);
236 break;
237 }
238 }
239
240 /* If we found no next symbol, we use the end of the section. */
241 if (!symbol_end) {
242 if (is_kernel_inittext(addr))
243 symbol_end = (unsigned long)_einittext;
244 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
245 symbol_end = (unsigned long)_end;
246 else
247 symbol_end = (unsigned long)_etext;
248 }
249
250 if (symbolsize)
251 *symbolsize = symbol_end - symbol_start;
252 if (offset)
253 *offset = addr - symbol_start;
254
255 return low;
256}
257
258/*
259 * Lookup an address but don't bother to find any names.
260 */
261int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
262 unsigned long *offset)
263{
264 char namebuf[KSYM_NAME_LEN];
265
266 if (is_ksym_addr(addr)) {
267 get_symbol_pos(addr, symbolsize, offset);
268 return 1;
269 }
270 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) ||
271 !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
272}
273
274/*
275 * Lookup an address
276 * - modname is set to NULL if it's in the kernel.
277 * - We guarantee that the returned name is valid until we reschedule even if.
278 * It resides in a module.
279 * - We also guarantee that modname will be valid until rescheduled.
280 */
281const char *kallsyms_lookup(unsigned long addr,
282 unsigned long *symbolsize,
283 unsigned long *offset,
284 char **modname, char *namebuf)
285{
286 const char *ret;
287
288 namebuf[KSYM_NAME_LEN - 1] = 0;
289 namebuf[0] = 0;
290
291 if (is_ksym_addr(addr)) {
292 unsigned long pos;
293
294 pos = get_symbol_pos(addr, symbolsize, offset);
295 /* Grab name */
296 kallsyms_expand_symbol(get_symbol_offset(pos),
297 namebuf, KSYM_NAME_LEN);
298 if (modname)
299 *modname = NULL;
300 return namebuf;
301 }
302
303 /* See if it's in a module or a BPF JITed image. */
304 ret = module_address_lookup(addr, symbolsize, offset,
305 modname, namebuf);
306 if (!ret)
307 ret = bpf_address_lookup(addr, symbolsize,
308 offset, modname, namebuf);
309
310 if (!ret)
311 ret = ftrace_mod_address_lookup(addr, symbolsize,
312 offset, modname, namebuf);
313 return ret;
314}
315
316int lookup_symbol_name(unsigned long addr, char *symname)
317{
318 symname[0] = '\0';
319 symname[KSYM_NAME_LEN - 1] = '\0';
320
321 if (is_ksym_addr(addr)) {
322 unsigned long pos;
323
324 pos = get_symbol_pos(addr, NULL, NULL);
325 /* Grab name */
326 kallsyms_expand_symbol(get_symbol_offset(pos),
327 symname, KSYM_NAME_LEN);
328 return 0;
329 }
330 /* See if it's in a module. */
331 return lookup_module_symbol_name(addr, symname);
332}
333
334int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
335 unsigned long *offset, char *modname, char *name)
336{
337 name[0] = '\0';
338 name[KSYM_NAME_LEN - 1] = '\0';
339
340 if (is_ksym_addr(addr)) {
341 unsigned long pos;
342
343 pos = get_symbol_pos(addr, size, offset);
344 /* Grab name */
345 kallsyms_expand_symbol(get_symbol_offset(pos),
346 name, KSYM_NAME_LEN);
347 modname[0] = '\0';
348 return 0;
349 }
350 /* See if it's in a module. */
351 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
352}
353
354/* Look up a kernel symbol and return it in a text buffer. */
355static int __sprint_symbol(char *buffer, unsigned long address,
356 int symbol_offset, int add_offset)
357{
358 char *modname;
359 const char *name;
360 unsigned long offset, size;
361 int len;
362
363 address += symbol_offset;
364 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
365 if (!name)
366 return sprintf(buffer, "0x%lx", address - symbol_offset);
367
368 if (name != buffer)
369 strcpy(buffer, name);
370 len = strlen(buffer);
371 offset -= symbol_offset;
372
373 if (add_offset)
374 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
375
376 if (modname)
377 len += sprintf(buffer + len, " [%s]", modname);
378
379 return len;
380}
381
382/**
383 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
384 * @buffer: buffer to be stored
385 * @address: address to lookup
386 *
387 * This function looks up a kernel symbol with @address and stores its name,
388 * offset, size and module name to @buffer if possible. If no symbol was found,
389 * just saves its @address as is.
390 *
391 * This function returns the number of bytes stored in @buffer.
392 */
393int sprint_symbol(char *buffer, unsigned long address)
394{
395 return __sprint_symbol(buffer, address, 0, 1);
396}
397EXPORT_SYMBOL_GPL(sprint_symbol);
398
399/**
400 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
401 * @buffer: buffer to be stored
402 * @address: address to lookup
403 *
404 * This function looks up a kernel symbol with @address and stores its name
405 * and module name to @buffer if possible. If no symbol was found, just saves
406 * its @address as is.
407 *
408 * This function returns the number of bytes stored in @buffer.
409 */
410int sprint_symbol_no_offset(char *buffer, unsigned long address)
411{
412 return __sprint_symbol(buffer, address, 0, 0);
413}
414EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
415
416/**
417 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
418 * @buffer: buffer to be stored
419 * @address: address to lookup
420 *
421 * This function is for stack backtrace and does the same thing as
422 * sprint_symbol() but with modified/decreased @address. If there is a
423 * tail-call to the function marked "noreturn", gcc optimized out code after
424 * the call so that the stack-saved return address could point outside of the
425 * caller. This function ensures that kallsyms will find the original caller
426 * by decreasing @address.
427 *
428 * This function returns the number of bytes stored in @buffer.
429 */
430int sprint_backtrace(char *buffer, unsigned long address)
431{
432 return __sprint_symbol(buffer, address, -1, 1);
433}
434
435/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
436struct kallsym_iter {
437 loff_t pos;
438 loff_t pos_arch_end;
439 loff_t pos_mod_end;
440 loff_t pos_ftrace_mod_end;
441 unsigned long value;
442 unsigned int nameoff; /* If iterating in core kernel symbols. */
443 char type;
444 char name[KSYM_NAME_LEN];
445 char module_name[MODULE_NAME_LEN];
446 int exported;
447 int show_value;
448};
449
450int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
451 char *type, char *name)
452{
453 return -EINVAL;
454}
455
456static int get_ksymbol_arch(struct kallsym_iter *iter)
457{
458 int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,
459 &iter->value, &iter->type,
460 iter->name);
461
462 if (ret < 0) {
463 iter->pos_arch_end = iter->pos;
464 return 0;
465 }
466
467 return 1;
468}
469
470static int get_ksymbol_mod(struct kallsym_iter *iter)
471{
472 int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,
473 &iter->value, &iter->type,
474 iter->name, iter->module_name,
475 &iter->exported);
476 if (ret < 0) {
477 iter->pos_mod_end = iter->pos;
478 return 0;
479 }
480
481 return 1;
482}
483
484static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
485{
486 int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
487 &iter->value, &iter->type,
488 iter->name, iter->module_name,
489 &iter->exported);
490 if (ret < 0) {
491 iter->pos_ftrace_mod_end = iter->pos;
492 return 0;
493 }
494
495 return 1;
496}
497
498static int get_ksymbol_bpf(struct kallsym_iter *iter)
499{
500 strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
501 iter->exported = 0;
502 return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
503 &iter->value, &iter->type,
504 iter->name) < 0 ? 0 : 1;
505}
506
507/* Returns space to next name. */
508static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
509{
510 unsigned off = iter->nameoff;
511
512 iter->module_name[0] = '\0';
513 iter->value = kallsyms_sym_address(iter->pos);
514
515 iter->type = kallsyms_get_symbol_type(off);
516
517 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
518
519 return off - iter->nameoff;
520}
521
522static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
523{
524 iter->name[0] = '\0';
525 iter->nameoff = get_symbol_offset(new_pos);
526 iter->pos = new_pos;
527 if (new_pos == 0) {
528 iter->pos_arch_end = 0;
529 iter->pos_mod_end = 0;
530 iter->pos_ftrace_mod_end = 0;
531 }
532}
533
534/*
535 * The end position (last + 1) of each additional kallsyms section is recorded
536 * in iter->pos_..._end as each section is added, and so can be used to
537 * determine which get_ksymbol_...() function to call next.
538 */
539static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
540{
541 iter->pos = pos;
542
543 if ((!iter->pos_arch_end || iter->pos_arch_end > pos) &&
544 get_ksymbol_arch(iter))
545 return 1;
546
547 if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
548 get_ksymbol_mod(iter))
549 return 1;
550
551 if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
552 get_ksymbol_ftrace_mod(iter))
553 return 1;
554
555 return get_ksymbol_bpf(iter);
556}
557
558/* Returns false if pos at or past end of file. */
559static int update_iter(struct kallsym_iter *iter, loff_t pos)
560{
561 /* Module symbols can be accessed randomly. */
562 if (pos >= kallsyms_num_syms)
563 return update_iter_mod(iter, pos);
564
565 /* If we're not on the desired position, reset to new position. */
566 if (pos != iter->pos)
567 reset_iter(iter, pos);
568
569 iter->nameoff += get_ksymbol_core(iter);
570 iter->pos++;
571
572 return 1;
573}
574
575static void *s_next(struct seq_file *m, void *p, loff_t *pos)
576{
577 (*pos)++;
578
579 if (!update_iter(m->private, *pos))
580 return NULL;
581 return p;
582}
583
584static void *s_start(struct seq_file *m, loff_t *pos)
585{
586 if (!update_iter(m->private, *pos))
587 return NULL;
588 return m->private;
589}
590
591static void s_stop(struct seq_file *m, void *p)
592{
593}
594
595static int s_show(struct seq_file *m, void *p)
596{
597 void *value;
598 struct kallsym_iter *iter = m->private;
599
600 /* Some debugging symbols have no name. Ignore them. */
601 if (!iter->name[0])
602 return 0;
603
604 value = iter->show_value ? (void *)iter->value : NULL;
605
606 if (iter->module_name[0]) {
607 char type;
608
609 /*
610 * Label it "global" if it is exported,
611 * "local" if not exported.
612 */
613 type = iter->exported ? toupper(iter->type) :
614 tolower(iter->type);
615 seq_printf(m, "%px %c %s\t[%s]\n", value,
616 type, iter->name, iter->module_name);
617 } else
618 seq_printf(m, "%px %c %s\n", value,
619 iter->type, iter->name);
620 return 0;
621}
622
623static const struct seq_operations kallsyms_op = {
624 .start = s_start,
625 .next = s_next,
626 .stop = s_stop,
627 .show = s_show
628};
629
630static inline int kallsyms_for_perf(void)
631{
632#ifdef CONFIG_PERF_EVENTS
633 extern int sysctl_perf_event_paranoid;
634 if (sysctl_perf_event_paranoid <= 1)
635 return 1;
636#endif
637 return 0;
638}
639
640/*
641 * We show kallsyms information even to normal users if we've enabled
642 * kernel profiling and are explicitly not paranoid (so kptr_restrict
643 * is clear, and sysctl_perf_event_paranoid isn't set).
644 *
645 * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
646 * block even that).
647 */
648int kallsyms_show_value(void)
649{
650 switch (kptr_restrict) {
651 case 0:
652 if (kallsyms_for_perf())
653 return 1;
654 /* fallthrough */
655 case 1:
656 if (has_capability_noaudit(current, CAP_SYSLOG))
657 return 1;
658 /* fallthrough */
659 default:
660 return 0;
661 }
662}
663
664static int kallsyms_open(struct inode *inode, struct file *file)
665{
666 /*
667 * We keep iterator in m->private, since normal case is to
668 * s_start from where we left off, so we avoid doing
669 * using get_symbol_offset for every symbol.
670 */
671 struct kallsym_iter *iter;
672 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
673 if (!iter)
674 return -ENOMEM;
675 reset_iter(iter, 0);
676
677 iter->show_value = kallsyms_show_value();
678 return 0;
679}
680
681#ifdef CONFIG_KGDB_KDB
682const char *kdb_walk_kallsyms(loff_t *pos)
683{
684 static struct kallsym_iter kdb_walk_kallsyms_iter;
685 if (*pos == 0) {
686 memset(&kdb_walk_kallsyms_iter, 0,
687 sizeof(kdb_walk_kallsyms_iter));
688 reset_iter(&kdb_walk_kallsyms_iter, 0);
689 }
690 while (1) {
691 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
692 return NULL;
693 ++*pos;
694 /* Some debugging symbols have no name. Ignore them. */
695 if (kdb_walk_kallsyms_iter.name[0])
696 return kdb_walk_kallsyms_iter.name;
697 }
698}
699#endif /* CONFIG_KGDB_KDB */
700
701static const struct file_operations kallsyms_operations = {
702 .open = kallsyms_open,
703 .read = seq_read,
704 .llseek = seq_lseek,
705 .release = seq_release_private,
706};
707
708static int __init kallsyms_init(void)
709{
710 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
711 return 0;
712}
713device_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, int add_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 offset -= symbol_offset;
362
363 if (add_offset)
364 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
365
366 if (modname)
367 len += sprintf(buffer + len, " [%s]", modname);
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, 1);
386}
387EXPORT_SYMBOL_GPL(sprint_symbol);
388
389/**
390 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
391 * @buffer: buffer to be stored
392 * @address: address to lookup
393 *
394 * This function looks up a kernel symbol with @address and stores its name
395 * and module name to @buffer if possible. If no symbol was found, just saves
396 * its @address as is.
397 *
398 * This function returns the number of bytes stored in @buffer.
399 */
400int sprint_symbol_no_offset(char *buffer, unsigned long address)
401{
402 return __sprint_symbol(buffer, address, 0, 0);
403}
404EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
405
406/**
407 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
408 * @buffer: buffer to be stored
409 * @address: address to lookup
410 *
411 * This function is for stack backtrace and does the same thing as
412 * sprint_symbol() but with modified/decreased @address. If there is a
413 * tail-call to the function marked "noreturn", gcc optimized out code after
414 * the call so that the stack-saved return address could point outside of the
415 * caller. This function ensures that kallsyms will find the original caller
416 * by decreasing @address.
417 *
418 * This function returns the number of bytes stored in @buffer.
419 */
420int sprint_backtrace(char *buffer, unsigned long address)
421{
422 return __sprint_symbol(buffer, address, -1, 1);
423}
424
425/* Look up a kernel symbol and print it to the kernel messages. */
426void __print_symbol(const char *fmt, unsigned long address)
427{
428 char buffer[KSYM_SYMBOL_LEN];
429
430 sprint_symbol(buffer, address);
431
432 printk(fmt, buffer);
433}
434EXPORT_SYMBOL(__print_symbol);
435
436/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
437struct kallsym_iter {
438 loff_t pos;
439 unsigned long value;
440 unsigned int nameoff; /* If iterating in core kernel symbols. */
441 char type;
442 char name[KSYM_NAME_LEN];
443 char module_name[MODULE_NAME_LEN];
444 int exported;
445};
446
447static int get_ksymbol_mod(struct kallsym_iter *iter)
448{
449 if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
450 &iter->type, iter->name, iter->module_name,
451 &iter->exported) < 0)
452 return 0;
453 return 1;
454}
455
456/* Returns space to next name. */
457static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
458{
459 unsigned off = iter->nameoff;
460
461 iter->module_name[0] = '\0';
462 iter->value = kallsyms_addresses[iter->pos];
463
464 iter->type = kallsyms_get_symbol_type(off);
465
466 off = kallsyms_expand_symbol(off, iter->name);
467
468 return off - iter->nameoff;
469}
470
471static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
472{
473 iter->name[0] = '\0';
474 iter->nameoff = get_symbol_offset(new_pos);
475 iter->pos = new_pos;
476}
477
478/* Returns false if pos at or past end of file. */
479static int update_iter(struct kallsym_iter *iter, loff_t pos)
480{
481 /* Module symbols can be accessed randomly. */
482 if (pos >= kallsyms_num_syms) {
483 iter->pos = pos;
484 return get_ksymbol_mod(iter);
485 }
486
487 /* If we're not on the desired position, reset to new position. */
488 if (pos != iter->pos)
489 reset_iter(iter, pos);
490
491 iter->nameoff += get_ksymbol_core(iter);
492 iter->pos++;
493
494 return 1;
495}
496
497static void *s_next(struct seq_file *m, void *p, loff_t *pos)
498{
499 (*pos)++;
500
501 if (!update_iter(m->private, *pos))
502 return NULL;
503 return p;
504}
505
506static void *s_start(struct seq_file *m, loff_t *pos)
507{
508 if (!update_iter(m->private, *pos))
509 return NULL;
510 return m->private;
511}
512
513static void s_stop(struct seq_file *m, void *p)
514{
515}
516
517static int s_show(struct seq_file *m, void *p)
518{
519 struct kallsym_iter *iter = m->private;
520
521 /* Some debugging symbols have no name. Ignore them. */
522 if (!iter->name[0])
523 return 0;
524
525 if (iter->module_name[0]) {
526 char type;
527
528 /*
529 * Label it "global" if it is exported,
530 * "local" if not exported.
531 */
532 type = iter->exported ? toupper(iter->type) :
533 tolower(iter->type);
534 seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
535 type, iter->name, iter->module_name);
536 } else
537 seq_printf(m, "%pK %c %s\n", (void *)iter->value,
538 iter->type, iter->name);
539 return 0;
540}
541
542static const struct seq_operations kallsyms_op = {
543 .start = s_start,
544 .next = s_next,
545 .stop = s_stop,
546 .show = s_show
547};
548
549static int kallsyms_open(struct inode *inode, struct file *file)
550{
551 /*
552 * We keep iterator in m->private, since normal case is to
553 * s_start from where we left off, so we avoid doing
554 * using get_symbol_offset for every symbol.
555 */
556 struct kallsym_iter *iter;
557 int ret;
558
559 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
560 if (!iter)
561 return -ENOMEM;
562 reset_iter(iter, 0);
563
564 ret = seq_open(file, &kallsyms_op);
565 if (ret == 0)
566 ((struct seq_file *)file->private_data)->private = iter;
567 else
568 kfree(iter);
569 return ret;
570}
571
572#ifdef CONFIG_KGDB_KDB
573const char *kdb_walk_kallsyms(loff_t *pos)
574{
575 static struct kallsym_iter kdb_walk_kallsyms_iter;
576 if (*pos == 0) {
577 memset(&kdb_walk_kallsyms_iter, 0,
578 sizeof(kdb_walk_kallsyms_iter));
579 reset_iter(&kdb_walk_kallsyms_iter, 0);
580 }
581 while (1) {
582 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
583 return NULL;
584 ++*pos;
585 /* Some debugging symbols have no name. Ignore them. */
586 if (kdb_walk_kallsyms_iter.name[0])
587 return kdb_walk_kallsyms_iter.name;
588 }
589}
590#endif /* CONFIG_KGDB_KDB */
591
592static const struct file_operations kallsyms_operations = {
593 .open = kallsyms_open,
594 .read = seq_read,
595 .llseek = seq_lseek,
596 .release = seq_release_private,
597};
598
599static int __init kallsyms_init(void)
600{
601 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
602 return 0;
603}
604device_initcall(kallsyms_init);