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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#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);