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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/build_bug.h>
29#include <linux/compiler.h>
30#include <linux/module.h>
31#include <linux/kernel.h>
32
33
34
35
36
37extern const unsigned long kallsyms_addresses[] __weak;
38extern const int kallsyms_offsets[] __weak;
39extern const u8 kallsyms_names[] __weak;
40
41
42
43
44
45extern const unsigned int kallsyms_num_syms
46__section(".rodata") __attribute__((weak));
47
48extern const unsigned long kallsyms_relative_base
49__section(".rodata") __attribute__((weak));
50
51extern const char kallsyms_token_table[] __weak;
52extern const u16 kallsyms_token_index[] __weak;
53
54extern const unsigned int kallsyms_markers[] __weak;
55
56
57
58
59
60
61static unsigned int kallsyms_expand_symbol(unsigned int off,
62 char *result, size_t maxlen)
63{
64 int len, skipped_first = 0;
65 const char *tptr;
66 const u8 *data;
67
68
69 data = &kallsyms_names[off];
70 len = *data;
71 data++;
72
73
74
75
76
77 off += len + 1;
78
79
80
81
82
83 while (len) {
84 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
85 data++;
86 len--;
87
88 while (*tptr) {
89 if (skipped_first) {
90 if (maxlen <= 1)
91 goto tail;
92 *result = *tptr;
93 result++;
94 maxlen--;
95 } else
96 skipped_first = 1;
97 tptr++;
98 }
99 }
100
101tail:
102 if (maxlen)
103 *result = '\0';
104
105
106 return off;
107}
108
109
110
111
112
113static char kallsyms_get_symbol_type(unsigned int off)
114{
115
116
117
118
119 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
120}
121
122
123
124
125
126
127static unsigned int get_symbol_offset(unsigned long pos)
128{
129 const u8 *name;
130 int i;
131
132
133
134
135
136 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
137
138
139
140
141
142
143
144 for (i = 0; i < (pos & 0xFF); i++)
145 name = name + (*name) + 1;
146
147 return name - kallsyms_names;
148}
149
150static unsigned long kallsyms_sym_address(int idx)
151{
152 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
153 return kallsyms_addresses[idx];
154
155
156 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
157 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
158
159
160 if (kallsyms_offsets[idx] >= 0)
161 return kallsyms_offsets[idx];
162
163
164 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
165}
166
167#if defined(CONFIG_CFI_CLANG) && defined(CONFIG_LTO_CLANG_THIN)
168
169
170
171
172
173
174static inline bool cleanup_symbol_name(char *s)
175{
176 char *res;
177
178 res = strrchr(s, '$');
179 if (res)
180 *res = '\0';
181
182 return res != NULL;
183}
184#else
185static inline bool cleanup_symbol_name(char *s) { return false; }
186#endif
187
188
189unsigned long kallsyms_lookup_name(const char *name)
190{
191 char namebuf[KSYM_NAME_LEN];
192 unsigned long i;
193 unsigned int off;
194
195 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
196 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
197
198 if (strcmp(namebuf, name) == 0)
199 return kallsyms_sym_address(i);
200
201 if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0)
202 return kallsyms_sym_address(i);
203 }
204 return module_kallsyms_lookup_name(name);
205}
206
207#ifdef CONFIG_LIVEPATCH
208
209
210
211
212int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
213 unsigned long),
214 void *data)
215{
216 char namebuf[KSYM_NAME_LEN];
217 unsigned long i;
218 unsigned int off;
219 int ret;
220
221 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
222 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
223 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
224 if (ret != 0)
225 return ret;
226 }
227 return 0;
228}
229#endif
230
231static unsigned long get_symbol_pos(unsigned long addr,
232 unsigned long *symbolsize,
233 unsigned long *offset)
234{
235 unsigned long symbol_start = 0, symbol_end = 0;
236 unsigned long i, low, high, mid;
237
238
239 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
240 BUG_ON(!kallsyms_addresses);
241 else
242 BUG_ON(!kallsyms_offsets);
243
244
245 low = 0;
246 high = kallsyms_num_syms;
247
248 while (high - low > 1) {
249 mid = low + (high - low) / 2;
250 if (kallsyms_sym_address(mid) <= addr)
251 low = mid;
252 else
253 high = mid;
254 }
255
256
257
258
259
260 while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
261 --low;
262
263 symbol_start = kallsyms_sym_address(low);
264
265
266 for (i = low + 1; i < kallsyms_num_syms; i++) {
267 if (kallsyms_sym_address(i) > symbol_start) {
268 symbol_end = kallsyms_sym_address(i);
269 break;
270 }
271 }
272
273
274 if (!symbol_end) {
275 if (is_kernel_inittext(addr))
276 symbol_end = (unsigned long)_einittext;
277 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
278 symbol_end = (unsigned long)_end;
279 else
280 symbol_end = (unsigned long)_etext;
281 }
282
283 if (symbolsize)
284 *symbolsize = symbol_end - symbol_start;
285 if (offset)
286 *offset = addr - symbol_start;
287
288 return low;
289}
290
291
292
293
294int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
295 unsigned long *offset)
296{
297 char namebuf[KSYM_NAME_LEN];
298
299 if (is_ksym_addr(addr)) {
300 get_symbol_pos(addr, symbolsize, offset);
301 return 1;
302 }
303 return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) ||
304 !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
305}
306
307static const char *kallsyms_lookup_buildid(unsigned long addr,
308 unsigned long *symbolsize,
309 unsigned long *offset, char **modname,
310 const unsigned char **modbuildid, char *namebuf)
311{
312 const char *ret;
313
314 namebuf[KSYM_NAME_LEN - 1] = 0;
315 namebuf[0] = 0;
316
317 if (is_ksym_addr(addr)) {
318 unsigned long pos;
319
320 pos = get_symbol_pos(addr, symbolsize, offset);
321
322 kallsyms_expand_symbol(get_symbol_offset(pos),
323 namebuf, KSYM_NAME_LEN);
324 if (modname)
325 *modname = NULL;
326 if (modbuildid)
327 *modbuildid = NULL;
328
329 ret = namebuf;
330 goto found;
331 }
332
333
334 ret = module_address_lookup(addr, symbolsize, offset,
335 modname, modbuildid, namebuf);
336 if (!ret)
337 ret = bpf_address_lookup(addr, symbolsize,
338 offset, modname, namebuf);
339
340 if (!ret)
341 ret = ftrace_mod_address_lookup(addr, symbolsize,
342 offset, modname, namebuf);
343
344found:
345 cleanup_symbol_name(namebuf);
346 return ret;
347}
348
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353
354
355
356const char *kallsyms_lookup(unsigned long addr,
357 unsigned long *symbolsize,
358 unsigned long *offset,
359 char **modname, char *namebuf)
360{
361 return kallsyms_lookup_buildid(addr, symbolsize, offset, modname,
362 NULL, namebuf);
363}
364
365int lookup_symbol_name(unsigned long addr, char *symname)
366{
367 int res;
368
369 symname[0] = '\0';
370 symname[KSYM_NAME_LEN - 1] = '\0';
371
372 if (is_ksym_addr(addr)) {
373 unsigned long pos;
374
375 pos = get_symbol_pos(addr, NULL, NULL);
376
377 kallsyms_expand_symbol(get_symbol_offset(pos),
378 symname, KSYM_NAME_LEN);
379 goto found;
380 }
381
382 res = lookup_module_symbol_name(addr, symname);
383 if (res)
384 return res;
385
386found:
387 cleanup_symbol_name(symname);
388 return 0;
389}
390
391int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
392 unsigned long *offset, char *modname, char *name)
393{
394 int res;
395
396 name[0] = '\0';
397 name[KSYM_NAME_LEN - 1] = '\0';
398
399 if (is_ksym_addr(addr)) {
400 unsigned long pos;
401
402 pos = get_symbol_pos(addr, size, offset);
403
404 kallsyms_expand_symbol(get_symbol_offset(pos),
405 name, KSYM_NAME_LEN);
406 modname[0] = '\0';
407 goto found;
408 }
409
410 res = lookup_module_symbol_attrs(addr, size, offset, modname, name);
411 if (res)
412 return res;
413
414found:
415 cleanup_symbol_name(name);
416 return 0;
417}
418
419
420static int __sprint_symbol(char *buffer, unsigned long address,
421 int symbol_offset, int add_offset, int add_buildid)
422{
423 char *modname;
424 const unsigned char *buildid;
425 const char *name;
426 unsigned long offset, size;
427 int len;
428
429 address += symbol_offset;
430 name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid,
431 buffer);
432 if (!name)
433 return sprintf(buffer, "0x%lx", address - symbol_offset);
434
435 if (name != buffer)
436 strcpy(buffer, name);
437 len = strlen(buffer);
438 offset -= symbol_offset;
439
440 if (add_offset)
441 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
442
443 if (modname) {
444 len += sprintf(buffer + len, " [%s", modname);
445#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
446 if (add_buildid && buildid) {
447
448#if IS_ENABLED(CONFIG_MODULES)
449 static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
450#endif
451 len += sprintf(buffer + len, " %20phN", buildid);
452 }
453#endif
454 len += sprintf(buffer + len, "]");
455 }
456
457 return len;
458}
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470
471int sprint_symbol(char *buffer, unsigned long address)
472{
473 return __sprint_symbol(buffer, address, 0, 1, 0);
474}
475EXPORT_SYMBOL_GPL(sprint_symbol);
476
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486
487
488int sprint_symbol_build_id(char *buffer, unsigned long address)
489{
490 return __sprint_symbol(buffer, address, 0, 1, 1);
491}
492EXPORT_SYMBOL_GPL(sprint_symbol_build_id);
493
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504
505int sprint_symbol_no_offset(char *buffer, unsigned long address)
506{
507 return __sprint_symbol(buffer, address, 0, 0, 0);
508}
509EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
510
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524
525int sprint_backtrace(char *buffer, unsigned long address)
526{
527 return __sprint_symbol(buffer, address, -1, 1, 0);
528}
529
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543
544
545int sprint_backtrace_build_id(char *buffer, unsigned long address)
546{
547 return __sprint_symbol(buffer, address, -1, 1, 1);
548}
549
550
551struct kallsym_iter {
552 loff_t pos;
553 loff_t pos_arch_end;
554 loff_t pos_mod_end;
555 loff_t pos_ftrace_mod_end;
556 loff_t pos_bpf_end;
557 unsigned long value;
558 unsigned int nameoff;
559 char type;
560 char name[KSYM_NAME_LEN];
561 char module_name[MODULE_NAME_LEN];
562 int exported;
563 int show_value;
564};
565
566int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
567 char *type, char *name)
568{
569 return -EINVAL;
570}
571
572static int get_ksymbol_arch(struct kallsym_iter *iter)
573{
574 int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,
575 &iter->value, &iter->type,
576 iter->name);
577
578 if (ret < 0) {
579 iter->pos_arch_end = iter->pos;
580 return 0;
581 }
582
583 return 1;
584}
585
586static int get_ksymbol_mod(struct kallsym_iter *iter)
587{
588 int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,
589 &iter->value, &iter->type,
590 iter->name, iter->module_name,
591 &iter->exported);
592 if (ret < 0) {
593 iter->pos_mod_end = iter->pos;
594 return 0;
595 }
596
597 return 1;
598}
599
600
601
602
603
604
605static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
606{
607 int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
608 &iter->value, &iter->type,
609 iter->name, iter->module_name,
610 &iter->exported);
611 if (ret < 0) {
612 iter->pos_ftrace_mod_end = iter->pos;
613 return 0;
614 }
615
616 return 1;
617}
618
619static int get_ksymbol_bpf(struct kallsym_iter *iter)
620{
621 int ret;
622
623 strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
624 iter->exported = 0;
625 ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
626 &iter->value, &iter->type,
627 iter->name);
628 if (ret < 0) {
629 iter->pos_bpf_end = iter->pos;
630 return 0;
631 }
632
633 return 1;
634}
635
636
637
638
639
640
641static int get_ksymbol_kprobe(struct kallsym_iter *iter)
642{
643 strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
644 iter->exported = 0;
645 return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
646 &iter->value, &iter->type,
647 iter->name) < 0 ? 0 : 1;
648}
649
650
651static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
652{
653 unsigned off = iter->nameoff;
654
655 iter->module_name[0] = '\0';
656 iter->value = kallsyms_sym_address(iter->pos);
657
658 iter->type = kallsyms_get_symbol_type(off);
659
660 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
661
662 return off - iter->nameoff;
663}
664
665static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
666{
667 iter->name[0] = '\0';
668 iter->nameoff = get_symbol_offset(new_pos);
669 iter->pos = new_pos;
670 if (new_pos == 0) {
671 iter->pos_arch_end = 0;
672 iter->pos_mod_end = 0;
673 iter->pos_ftrace_mod_end = 0;
674 iter->pos_bpf_end = 0;
675 }
676}
677
678
679
680
681
682
683static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
684{
685 iter->pos = pos;
686
687 if ((!iter->pos_arch_end || iter->pos_arch_end > pos) &&
688 get_ksymbol_arch(iter))
689 return 1;
690
691 if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
692 get_ksymbol_mod(iter))
693 return 1;
694
695 if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
696 get_ksymbol_ftrace_mod(iter))
697 return 1;
698
699 if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
700 get_ksymbol_bpf(iter))
701 return 1;
702
703 return get_ksymbol_kprobe(iter);
704}
705
706
707static int update_iter(struct kallsym_iter *iter, loff_t pos)
708{
709
710 if (pos >= kallsyms_num_syms)
711 return update_iter_mod(iter, pos);
712
713
714 if (pos != iter->pos)
715 reset_iter(iter, pos);
716
717 iter->nameoff += get_ksymbol_core(iter);
718 iter->pos++;
719
720 return 1;
721}
722
723static void *s_next(struct seq_file *m, void *p, loff_t *pos)
724{
725 (*pos)++;
726
727 if (!update_iter(m->private, *pos))
728 return NULL;
729 return p;
730}
731
732static void *s_start(struct seq_file *m, loff_t *pos)
733{
734 if (!update_iter(m->private, *pos))
735 return NULL;
736 return m->private;
737}
738
739static void s_stop(struct seq_file *m, void *p)
740{
741}
742
743static int s_show(struct seq_file *m, void *p)
744{
745 void *value;
746 struct kallsym_iter *iter = m->private;
747
748
749 if (!iter->name[0])
750 return 0;
751
752 value = iter->show_value ? (void *)iter->value : NULL;
753
754 if (iter->module_name[0]) {
755 char type;
756
757
758
759
760
761 type = iter->exported ? toupper(iter->type) :
762 tolower(iter->type);
763 seq_printf(m, "%px %c %s\t[%s]\n", value,
764 type, iter->name, iter->module_name);
765 } else
766 seq_printf(m, "%px %c %s\n", value,
767 iter->type, iter->name);
768 return 0;
769}
770
771static const struct seq_operations kallsyms_op = {
772 .start = s_start,
773 .next = s_next,
774 .stop = s_stop,
775 .show = s_show
776};
777
778static inline int kallsyms_for_perf(void)
779{
780#ifdef CONFIG_PERF_EVENTS
781 extern int sysctl_perf_event_paranoid;
782 if (sysctl_perf_event_paranoid <= 1)
783 return 1;
784#endif
785 return 0;
786}
787
788
789
790
791
792
793
794
795
796bool kallsyms_show_value(const struct cred *cred)
797{
798 switch (kptr_restrict) {
799 case 0:
800 if (kallsyms_for_perf())
801 return true;
802 fallthrough;
803 case 1:
804 if (security_capable(cred, &init_user_ns, CAP_SYSLOG,
805 CAP_OPT_NOAUDIT) == 0)
806 return true;
807 fallthrough;
808 default:
809 return false;
810 }
811}
812
813static int kallsyms_open(struct inode *inode, struct file *file)
814{
815
816
817
818
819
820 struct kallsym_iter *iter;
821 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
822 if (!iter)
823 return -ENOMEM;
824 reset_iter(iter, 0);
825
826
827
828
829
830 iter->show_value = kallsyms_show_value(file->f_cred);
831 return 0;
832}
833
834#ifdef CONFIG_KGDB_KDB
835const char *kdb_walk_kallsyms(loff_t *pos)
836{
837 static struct kallsym_iter kdb_walk_kallsyms_iter;
838 if (*pos == 0) {
839 memset(&kdb_walk_kallsyms_iter, 0,
840 sizeof(kdb_walk_kallsyms_iter));
841 reset_iter(&kdb_walk_kallsyms_iter, 0);
842 }
843 while (1) {
844 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
845 return NULL;
846 ++*pos;
847
848 if (kdb_walk_kallsyms_iter.name[0])
849 return kdb_walk_kallsyms_iter.name;
850 }
851}
852#endif
853
854static const struct proc_ops kallsyms_proc_ops = {
855 .proc_open = kallsyms_open,
856 .proc_read = seq_read,
857 .proc_lseek = seq_lseek,
858 .proc_release = seq_release_private,
859};
860
861static int __init kallsyms_init(void)
862{
863 proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
864 return 0;
865}
866device_initcall(kallsyms_init);
867