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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>
23#include <linux/ctype.h>
24#include <linux/slab.h>
25#include <linux/filter.h>
26#include <linux/ftrace.h>
27#include <linux/kprobes.h>
28#include <linux/compiler.h>
29
30
31
32
33
34extern const unsigned long kallsyms_addresses[] __weak;
35extern const int kallsyms_offsets[] __weak;
36extern const u8 kallsyms_names[] __weak;
37
38
39
40
41
42extern const unsigned int kallsyms_num_syms
43__section(".rodata") __attribute__((weak));
44
45extern const unsigned long kallsyms_relative_base
46__section(".rodata") __attribute__((weak));
47
48extern const char kallsyms_token_table[] __weak;
49extern const u16 kallsyms_token_index[] __weak;
50
51extern const unsigned int kallsyms_markers[] __weak;
52
53
54
55
56
57
58static unsigned int kallsyms_expand_symbol(unsigned int off,
59 char *result, size_t maxlen)
60{
61 int len, skipped_first = 0;
62 const char *tptr;
63 const u8 *data;
64
65
66 data = &kallsyms_names[off];
67 len = *data;
68 data++;
69
70
71
72
73
74 off += len + 1;
75
76
77
78
79
80 while (len) {
81 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
82 data++;
83 len--;
84
85 while (*tptr) {
86 if (skipped_first) {
87 if (maxlen <= 1)
88 goto tail;
89 *result = *tptr;
90 result++;
91 maxlen--;
92 } else
93 skipped_first = 1;
94 tptr++;
95 }
96 }
97
98tail:
99 if (maxlen)
100 *result = '\0';
101
102
103 return off;
104}
105
106
107
108
109
110static char kallsyms_get_symbol_type(unsigned int off)
111{
112
113
114
115
116 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
117}
118
119
120
121
122
123
124static unsigned int get_symbol_offset(unsigned long pos)
125{
126 const u8 *name;
127 int i;
128
129
130
131
132
133 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
134
135
136
137
138
139
140
141 for (i = 0; i < (pos & 0xFF); i++)
142 name = name + (*name) + 1;
143
144 return name - kallsyms_names;
145}
146
147static unsigned long kallsyms_sym_address(int idx)
148{
149 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
150 return kallsyms_addresses[idx];
151
152
153 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
154 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
155
156
157 if (kallsyms_offsets[idx] >= 0)
158 return kallsyms_offsets[idx];
159
160
161 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
162}
163
164#if defined(CONFIG_CFI_CLANG) && defined(CONFIG_LTO_CLANG_THIN)
165
166
167
168
169
170
171static inline bool cleanup_symbol_name(char *s)
172{
173 char *res;
174
175 res = strrchr(s, '$');
176 if (res)
177 *res = '\0';
178
179 return res != NULL;
180}
181#else
182static inline bool cleanup_symbol_name(char *s) { return false; }
183#endif
184
185
186unsigned long kallsyms_lookup_name(const char *name)
187{
188 char namebuf[KSYM_NAME_LEN];
189 unsigned long i;
190 unsigned int off;
191
192 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
193 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
194
195 if (strcmp(namebuf, name) == 0)
196 return kallsyms_sym_address(i);
197
198 if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0)
199 return kallsyms_sym_address(i);
200 }
201 return module_kallsyms_lookup_name(name);
202}
203
204#ifdef CONFIG_LIVEPATCH
205
206
207
208
209int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
210 unsigned long),
211 void *data)
212{
213 char namebuf[KSYM_NAME_LEN];
214 unsigned long i;
215 unsigned int off;
216 int ret;
217
218 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
219 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
220 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
221 if (ret != 0)
222 return ret;
223 }
224 return 0;
225}
226#endif
227
228static unsigned long get_symbol_pos(unsigned long addr,
229 unsigned long *symbolsize,
230 unsigned long *offset)
231{
232 unsigned long symbol_start = 0, symbol_end = 0;
233 unsigned long i, low, high, mid;
234
235
236 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
237 BUG_ON(!kallsyms_addresses);
238 else
239 BUG_ON(!kallsyms_offsets);
240
241
242 low = 0;
243 high = kallsyms_num_syms;
244
245 while (high - low > 1) {
246 mid = low + (high - low) / 2;
247 if (kallsyms_sym_address(mid) <= addr)
248 low = mid;
249 else
250 high = mid;
251 }
252
253
254
255
256
257 while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
258 --low;
259
260 symbol_start = kallsyms_sym_address(low);
261
262
263 for (i = low + 1; i < kallsyms_num_syms; i++) {
264 if (kallsyms_sym_address(i) > symbol_start) {
265 symbol_end = kallsyms_sym_address(i);
266 break;
267 }
268 }
269
270
271 if (!symbol_end) {
272 if (is_kernel_inittext(addr))
273 symbol_end = (unsigned long)_einittext;
274 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
275 symbol_end = (unsigned long)_end;
276 else
277 symbol_end = (unsigned long)_etext;
278 }
279
280 if (symbolsize)
281 *symbolsize = symbol_end - symbol_start;
282 if (offset)
283 *offset = addr - symbol_start;
284
285 return low;
286}
287
288
289
290
291int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
292 unsigned long *offset)
293{
294 char namebuf[KSYM_NAME_LEN];
295
296 if (is_ksym_addr(addr)) {
297 get_symbol_pos(addr, symbolsize, offset);
298 return 1;
299 }
300 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) ||
301 !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
302}
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309
310
311const char *kallsyms_lookup(unsigned long addr,
312 unsigned long *symbolsize,
313 unsigned long *offset,
314 char **modname, char *namebuf)
315{
316 const char *ret;
317
318 namebuf[KSYM_NAME_LEN - 1] = 0;
319 namebuf[0] = 0;
320
321 if (is_ksym_addr(addr)) {
322 unsigned long pos;
323
324 pos = get_symbol_pos(addr, symbolsize, offset);
325
326 kallsyms_expand_symbol(get_symbol_offset(pos),
327 namebuf, KSYM_NAME_LEN);
328 if (modname)
329 *modname = NULL;
330
331 ret = namebuf;
332 goto found;
333 }
334
335
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);
341
342 if (!ret)
343 ret = ftrace_mod_address_lookup(addr, symbolsize,
344 offset, modname, namebuf);
345
346found:
347 cleanup_symbol_name(namebuf);
348 return ret;
349}
350
351int lookup_symbol_name(unsigned long addr, char *symname)
352{
353 int res;
354
355 symname[0] = '\0';
356 symname[KSYM_NAME_LEN - 1] = '\0';
357
358 if (is_ksym_addr(addr)) {
359 unsigned long pos;
360
361 pos = get_symbol_pos(addr, NULL, NULL);
362
363 kallsyms_expand_symbol(get_symbol_offset(pos),
364 symname, KSYM_NAME_LEN);
365 goto found;
366 }
367
368 res = lookup_module_symbol_name(addr, symname);
369 if (res)
370 return res;
371
372found:
373 cleanup_symbol_name(symname);
374 return 0;
375}
376
377int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
378 unsigned long *offset, char *modname, char *name)
379{
380 int res;
381
382 name[0] = '\0';
383 name[KSYM_NAME_LEN - 1] = '\0';
384
385 if (is_ksym_addr(addr)) {
386 unsigned long pos;
387
388 pos = get_symbol_pos(addr, size, offset);
389
390 kallsyms_expand_symbol(get_symbol_offset(pos),
391 name, KSYM_NAME_LEN);
392 modname[0] = '\0';
393 goto found;
394 }
395
396 res = lookup_module_symbol_attrs(addr, size, offset, modname, name);
397 if (res)
398 return res;
399
400found:
401 cleanup_symbol_name(name);
402 return 0;
403}
404
405
406static int __sprint_symbol(char *buffer, unsigned long address,
407 int symbol_offset, int add_offset)
408{
409 char *modname;
410 const char *name;
411 unsigned long offset, size;
412 int len;
413
414 address += symbol_offset;
415 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
416 if (!name)
417 return sprintf(buffer, "0x%lx", address - symbol_offset);
418
419 if (name != buffer)
420 strcpy(buffer, name);
421 len = strlen(buffer);
422 offset -= symbol_offset;
423
424 if (add_offset)
425 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
426
427 if (modname)
428 len += sprintf(buffer + len, " [%s]", modname);
429
430 return len;
431}
432
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443
444int sprint_symbol(char *buffer, unsigned long address)
445{
446 return __sprint_symbol(buffer, address, 0, 1);
447}
448EXPORT_SYMBOL_GPL(sprint_symbol);
449
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460
461int sprint_symbol_no_offset(char *buffer, unsigned long address)
462{
463 return __sprint_symbol(buffer, address, 0, 0);
464}
465EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
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480
481int sprint_backtrace(char *buffer, unsigned long address)
482{
483 return __sprint_symbol(buffer, address, -1, 1);
484}
485
486
487struct kallsym_iter {
488 loff_t pos;
489 loff_t pos_arch_end;
490 loff_t pos_mod_end;
491 loff_t pos_ftrace_mod_end;
492 loff_t pos_bpf_end;
493 unsigned long value;
494 unsigned int nameoff;
495 char type;
496 char name[KSYM_NAME_LEN];
497 char module_name[MODULE_NAME_LEN];
498 int exported;
499 int show_value;
500};
501
502int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
503 char *type, char *name)
504{
505 return -EINVAL;
506}
507
508static int get_ksymbol_arch(struct kallsym_iter *iter)
509{
510 int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,
511 &iter->value, &iter->type,
512 iter->name);
513
514 if (ret < 0) {
515 iter->pos_arch_end = iter->pos;
516 return 0;
517 }
518
519 return 1;
520}
521
522static int get_ksymbol_mod(struct kallsym_iter *iter)
523{
524 int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,
525 &iter->value, &iter->type,
526 iter->name, iter->module_name,
527 &iter->exported);
528 if (ret < 0) {
529 iter->pos_mod_end = iter->pos;
530 return 0;
531 }
532
533 return 1;
534}
535
536
537
538
539
540
541static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
542{
543 int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
544 &iter->value, &iter->type,
545 iter->name, iter->module_name,
546 &iter->exported);
547 if (ret < 0) {
548 iter->pos_ftrace_mod_end = iter->pos;
549 return 0;
550 }
551
552 return 1;
553}
554
555static int get_ksymbol_bpf(struct kallsym_iter *iter)
556{
557 int ret;
558
559 strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
560 iter->exported = 0;
561 ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
562 &iter->value, &iter->type,
563 iter->name);
564 if (ret < 0) {
565 iter->pos_bpf_end = iter->pos;
566 return 0;
567 }
568
569 return 1;
570}
571
572
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574
575
576
577static int get_ksymbol_kprobe(struct kallsym_iter *iter)
578{
579 strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
580 iter->exported = 0;
581 return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
582 &iter->value, &iter->type,
583 iter->name) < 0 ? 0 : 1;
584}
585
586
587static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
588{
589 unsigned off = iter->nameoff;
590
591 iter->module_name[0] = '\0';
592 iter->value = kallsyms_sym_address(iter->pos);
593
594 iter->type = kallsyms_get_symbol_type(off);
595
596 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
597
598 return off - iter->nameoff;
599}
600
601static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
602{
603 iter->name[0] = '\0';
604 iter->nameoff = get_symbol_offset(new_pos);
605 iter->pos = new_pos;
606 if (new_pos == 0) {
607 iter->pos_arch_end = 0;
608 iter->pos_mod_end = 0;
609 iter->pos_ftrace_mod_end = 0;
610 iter->pos_bpf_end = 0;
611 }
612}
613
614
615
616
617
618
619static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
620{
621 iter->pos = pos;
622
623 if ((!iter->pos_arch_end || iter->pos_arch_end > pos) &&
624 get_ksymbol_arch(iter))
625 return 1;
626
627 if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
628 get_ksymbol_mod(iter))
629 return 1;
630
631 if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
632 get_ksymbol_ftrace_mod(iter))
633 return 1;
634
635 if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
636 get_ksymbol_bpf(iter))
637 return 1;
638
639 return get_ksymbol_kprobe(iter);
640}
641
642
643static int update_iter(struct kallsym_iter *iter, loff_t pos)
644{
645
646 if (pos >= kallsyms_num_syms)
647 return update_iter_mod(iter, pos);
648
649
650 if (pos != iter->pos)
651 reset_iter(iter, pos);
652
653 iter->nameoff += get_ksymbol_core(iter);
654 iter->pos++;
655
656 return 1;
657}
658
659static void *s_next(struct seq_file *m, void *p, loff_t *pos)
660{
661 (*pos)++;
662
663 if (!update_iter(m->private, *pos))
664 return NULL;
665 return p;
666}
667
668static void *s_start(struct seq_file *m, loff_t *pos)
669{
670 if (!update_iter(m->private, *pos))
671 return NULL;
672 return m->private;
673}
674
675static void s_stop(struct seq_file *m, void *p)
676{
677}
678
679static int s_show(struct seq_file *m, void *p)
680{
681 void *value;
682 struct kallsym_iter *iter = m->private;
683
684
685 if (!iter->name[0])
686 return 0;
687
688 value = iter->show_value ? (void *)iter->value : NULL;
689
690 if (iter->module_name[0]) {
691 char type;
692
693
694
695
696
697 type = iter->exported ? toupper(iter->type) :
698 tolower(iter->type);
699 seq_printf(m, "%px %c %s\t[%s]\n", value,
700 type, iter->name, iter->module_name);
701 } else
702 seq_printf(m, "%px %c %s\n", value,
703 iter->type, iter->name);
704 return 0;
705}
706
707static const struct seq_operations kallsyms_op = {
708 .start = s_start,
709 .next = s_next,
710 .stop = s_stop,
711 .show = s_show
712};
713
714static inline int kallsyms_for_perf(void)
715{
716#ifdef CONFIG_PERF_EVENTS
717 extern int sysctl_perf_event_paranoid;
718 if (sysctl_perf_event_paranoid <= 1)
719 return 1;
720#endif
721 return 0;
722}
723
724
725
726
727
728
729
730
731
732bool kallsyms_show_value(const struct cred *cred)
733{
734 switch (kptr_restrict) {
735 case 0:
736 if (kallsyms_for_perf())
737 return true;
738 fallthrough;
739 case 1:
740 if (security_capable(cred, &init_user_ns, CAP_SYSLOG,
741 CAP_OPT_NOAUDIT) == 0)
742 return true;
743 fallthrough;
744 default:
745 return false;
746 }
747}
748
749static int kallsyms_open(struct inode *inode, struct file *file)
750{
751
752
753
754
755
756 struct kallsym_iter *iter;
757 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
758 if (!iter)
759 return -ENOMEM;
760 reset_iter(iter, 0);
761
762
763
764
765
766 iter->show_value = kallsyms_show_value(file->f_cred);
767 return 0;
768}
769
770#ifdef CONFIG_KGDB_KDB
771const char *kdb_walk_kallsyms(loff_t *pos)
772{
773 static struct kallsym_iter kdb_walk_kallsyms_iter;
774 if (*pos == 0) {
775 memset(&kdb_walk_kallsyms_iter, 0,
776 sizeof(kdb_walk_kallsyms_iter));
777 reset_iter(&kdb_walk_kallsyms_iter, 0);
778 }
779 while (1) {
780 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
781 return NULL;
782 ++*pos;
783
784 if (kdb_walk_kallsyms_iter.name[0])
785 return kdb_walk_kallsyms_iter.name;
786 }
787}
788#endif
789
790static const struct proc_ops kallsyms_proc_ops = {
791 .proc_open = kallsyms_open,
792 .proc_read = seq_read,
793 .proc_lseek = seq_lseek,
794 .proc_release = seq_release_private,
795};
796
797static int __init kallsyms_init(void)
798{
799 proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
800 return 0;
801}
802device_initcall(kallsyms_init);
803