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/kprobes.h>
28 #include <linux/compiler.h>
29
30 /*
31 * These will be re-linked against their real values
32 * during the second link stage.
33 */
34 extern const unsigned long kallsyms_addresses[] __weak;
35 extern const int kallsyms_offsets[] __weak;
36 extern const u8 kallsyms_names[] __weak;
37
38 /*
39 * Tell the compiler that the count isn't in the small data section if the arch
40 * has one (eg: FRV).
41 */
42 extern const unsigned int kallsyms_num_syms
43 __section(".rodata") __attribute__((weak));
44
45 extern const unsigned long kallsyms_relative_base
46 __section(".rodata") __attribute__((weak));
47
48 extern const char kallsyms_token_table[] __weak;
49 extern const u16 kallsyms_token_index[] __weak;
50
51 extern const unsigned int kallsyms_markers[] __weak;
52
53 /*
54 * Expand a compressed symbol data into the resulting uncompressed string,
55 * if uncompressed string is too long (>= maxlen), it will be truncated,
56 * given the offset to where the symbol is in the compressed stream.
57 */
kallsyms_expand_symbol(unsigned int off,char * result,size_t maxlen)58 static 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 /* Get the compressed symbol length from the first symbol byte. */
66 data = &kallsyms_names[off];
67 len = *data;
68 data++;
69
70 /*
71 * Update the offset to return the offset for the next symbol on
72 * the compressed stream.
73 */
74 off += len + 1;
75
76 /*
77 * For every byte on the compressed symbol data, copy the table
78 * entry for that byte.
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
98 tail:
99 if (maxlen)
100 *result = '\0';
101
102 /* Return to offset to the next symbol. */
103 return off;
104 }
105
106 /*
107 * Get symbol type information. This is encoded as a single char at the
108 * beginning of the symbol name.
109 */
kallsyms_get_symbol_type(unsigned int off)110 static char kallsyms_get_symbol_type(unsigned int off)
111 {
112 /*
113 * Get just the first code, look it up in the token table,
114 * and return the first char from this token.
115 */
116 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
117 }
118
119
120 /*
121 * Find the offset on the compressed stream given and index in the
122 * kallsyms array.
123 */
get_symbol_offset(unsigned long pos)124 static unsigned int get_symbol_offset(unsigned long pos)
125 {
126 const u8 *name;
127 int i;
128
129 /*
130 * Use the closest marker we have. We have markers every 256 positions,
131 * so that should be close enough.
132 */
133 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
134
135 /*
136 * Sequentially scan all the symbols up to the point we're searching
137 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
138 * so we just need to add the len to the current pointer for every
139 * symbol we wish to skip.
140 */
141 for (i = 0; i < (pos & 0xFF); i++)
142 name = name + (*name) + 1;
143
144 return name - kallsyms_names;
145 }
146
kallsyms_sym_address(int idx)147 static unsigned long kallsyms_sym_address(int idx)
148 {
149 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
150 return kallsyms_addresses[idx];
151
152 /* values are unsigned offsets if --absolute-percpu is not in effect */
153 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
154 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
155
156 /* ...otherwise, positive offsets are absolute values */
157 if (kallsyms_offsets[idx] >= 0)
158 return kallsyms_offsets[idx];
159
160 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
161 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
162 }
163
164 /* Lookup the address for this symbol. Returns 0 if not found. */
kallsyms_lookup_name(const char * name)165 unsigned long kallsyms_lookup_name(const char *name)
166 {
167 char namebuf[KSYM_NAME_LEN];
168 unsigned long i;
169 unsigned int off;
170
171 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
172 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
173
174 if (strcmp(namebuf, name) == 0)
175 return kallsyms_sym_address(i);
176 }
177 return module_kallsyms_lookup_name(name);
178 }
179
kallsyms_on_each_symbol(int (* fn)(void *,const char *,struct module *,unsigned long),void * data)180 int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
181 unsigned long),
182 void *data)
183 {
184 char namebuf[KSYM_NAME_LEN];
185 unsigned long i;
186 unsigned int off;
187 int ret;
188
189 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
190 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
191 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
192 if (ret != 0)
193 return ret;
194 }
195 return module_kallsyms_on_each_symbol(fn, data);
196 }
197
get_symbol_pos(unsigned long addr,unsigned long * symbolsize,unsigned long * offset)198 static 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 */
kallsyms_lookup_size_offset(unsigned long addr,unsigned long * symbolsize,unsigned long * offset)261 int 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 */
kallsyms_lookup(unsigned long addr,unsigned long * symbolsize,unsigned long * offset,char ** modname,char * namebuf)281 const 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
lookup_symbol_name(unsigned long addr,char * symname)316 int 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
lookup_symbol_attrs(unsigned long addr,unsigned long * size,unsigned long * offset,char * modname,char * name)334 int 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. */
__sprint_symbol(char * buffer,unsigned long address,int symbol_offset,int add_offset)355 static 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 */
sprint_symbol(char * buffer,unsigned long address)393 int sprint_symbol(char *buffer, unsigned long address)
394 {
395 return __sprint_symbol(buffer, address, 0, 1);
396 }
397 EXPORT_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 */
sprint_symbol_no_offset(char * buffer,unsigned long address)410 int sprint_symbol_no_offset(char *buffer, unsigned long address)
411 {
412 return __sprint_symbol(buffer, address, 0, 0);
413 }
414 EXPORT_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 */
sprint_backtrace(char * buffer,unsigned long address)430 int 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. */
436 struct 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 loff_t pos_bpf_end;
442 unsigned long value;
443 unsigned int nameoff; /* If iterating in core kernel symbols. */
444 char type;
445 char name[KSYM_NAME_LEN];
446 char module_name[MODULE_NAME_LEN];
447 int exported;
448 int show_value;
449 };
450
arch_get_kallsym(unsigned int symnum,unsigned long * value,char * type,char * name)451 int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
452 char *type, char *name)
453 {
454 return -EINVAL;
455 }
456
get_ksymbol_arch(struct kallsym_iter * iter)457 static int get_ksymbol_arch(struct kallsym_iter *iter)
458 {
459 int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,
460 &iter->value, &iter->type,
461 iter->name);
462
463 if (ret < 0) {
464 iter->pos_arch_end = iter->pos;
465 return 0;
466 }
467
468 return 1;
469 }
470
get_ksymbol_mod(struct kallsym_iter * iter)471 static int get_ksymbol_mod(struct kallsym_iter *iter)
472 {
473 int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,
474 &iter->value, &iter->type,
475 iter->name, iter->module_name,
476 &iter->exported);
477 if (ret < 0) {
478 iter->pos_mod_end = iter->pos;
479 return 0;
480 }
481
482 return 1;
483 }
484
485 /*
486 * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
487 * purposes. In that case "__builtin__ftrace" is used as a module name, even
488 * though "__builtin__ftrace" is not a module.
489 */
get_ksymbol_ftrace_mod(struct kallsym_iter * iter)490 static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
491 {
492 int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
493 &iter->value, &iter->type,
494 iter->name, iter->module_name,
495 &iter->exported);
496 if (ret < 0) {
497 iter->pos_ftrace_mod_end = iter->pos;
498 return 0;
499 }
500
501 return 1;
502 }
503
get_ksymbol_bpf(struct kallsym_iter * iter)504 static int get_ksymbol_bpf(struct kallsym_iter *iter)
505 {
506 int ret;
507
508 strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
509 iter->exported = 0;
510 ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
511 &iter->value, &iter->type,
512 iter->name);
513 if (ret < 0) {
514 iter->pos_bpf_end = iter->pos;
515 return 0;
516 }
517
518 return 1;
519 }
520
521 /*
522 * This uses "__builtin__kprobes" as a module name for symbols for pages
523 * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
524 * module.
525 */
get_ksymbol_kprobe(struct kallsym_iter * iter)526 static int get_ksymbol_kprobe(struct kallsym_iter *iter)
527 {
528 strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
529 iter->exported = 0;
530 return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
531 &iter->value, &iter->type,
532 iter->name) < 0 ? 0 : 1;
533 }
534
535 /* Returns space to next name. */
get_ksymbol_core(struct kallsym_iter * iter)536 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
537 {
538 unsigned off = iter->nameoff;
539
540 iter->module_name[0] = '\0';
541 iter->value = kallsyms_sym_address(iter->pos);
542
543 iter->type = kallsyms_get_symbol_type(off);
544
545 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
546
547 return off - iter->nameoff;
548 }
549
reset_iter(struct kallsym_iter * iter,loff_t new_pos)550 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
551 {
552 iter->name[0] = '\0';
553 iter->nameoff = get_symbol_offset(new_pos);
554 iter->pos = new_pos;
555 if (new_pos == 0) {
556 iter->pos_arch_end = 0;
557 iter->pos_mod_end = 0;
558 iter->pos_ftrace_mod_end = 0;
559 iter->pos_bpf_end = 0;
560 }
561 }
562
563 /*
564 * The end position (last + 1) of each additional kallsyms section is recorded
565 * in iter->pos_..._end as each section is added, and so can be used to
566 * determine which get_ksymbol_...() function to call next.
567 */
update_iter_mod(struct kallsym_iter * iter,loff_t pos)568 static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
569 {
570 iter->pos = pos;
571
572 if ((!iter->pos_arch_end || iter->pos_arch_end > pos) &&
573 get_ksymbol_arch(iter))
574 return 1;
575
576 if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
577 get_ksymbol_mod(iter))
578 return 1;
579
580 if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
581 get_ksymbol_ftrace_mod(iter))
582 return 1;
583
584 if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
585 get_ksymbol_bpf(iter))
586 return 1;
587
588 return get_ksymbol_kprobe(iter);
589 }
590
591 /* Returns false if pos at or past end of file. */
update_iter(struct kallsym_iter * iter,loff_t pos)592 static int update_iter(struct kallsym_iter *iter, loff_t pos)
593 {
594 /* Module symbols can be accessed randomly. */
595 if (pos >= kallsyms_num_syms)
596 return update_iter_mod(iter, pos);
597
598 /* If we're not on the desired position, reset to new position. */
599 if (pos != iter->pos)
600 reset_iter(iter, pos);
601
602 iter->nameoff += get_ksymbol_core(iter);
603 iter->pos++;
604
605 return 1;
606 }
607
s_next(struct seq_file * m,void * p,loff_t * pos)608 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
609 {
610 (*pos)++;
611
612 if (!update_iter(m->private, *pos))
613 return NULL;
614 return p;
615 }
616
s_start(struct seq_file * m,loff_t * pos)617 static void *s_start(struct seq_file *m, loff_t *pos)
618 {
619 if (!update_iter(m->private, *pos))
620 return NULL;
621 return m->private;
622 }
623
s_stop(struct seq_file * m,void * p)624 static void s_stop(struct seq_file *m, void *p)
625 {
626 }
627
s_show(struct seq_file * m,void * p)628 static int s_show(struct seq_file *m, void *p)
629 {
630 void *value;
631 struct kallsym_iter *iter = m->private;
632
633 /* Some debugging symbols have no name. Ignore them. */
634 if (!iter->name[0])
635 return 0;
636
637 value = iter->show_value ? (void *)iter->value : NULL;
638
639 if (iter->module_name[0]) {
640 char type;
641
642 /*
643 * Label it "global" if it is exported,
644 * "local" if not exported.
645 */
646 type = iter->exported ? toupper(iter->type) :
647 tolower(iter->type);
648 seq_printf(m, "%px %c %s\t[%s]\n", value,
649 type, iter->name, iter->module_name);
650 } else
651 seq_printf(m, "%px %c %s\n", value,
652 iter->type, iter->name);
653 return 0;
654 }
655
656 static const struct seq_operations kallsyms_op = {
657 .start = s_start,
658 .next = s_next,
659 .stop = s_stop,
660 .show = s_show
661 };
662
kallsyms_for_perf(void)663 static inline int kallsyms_for_perf(void)
664 {
665 #ifdef CONFIG_PERF_EVENTS
666 extern int sysctl_perf_event_paranoid;
667 if (sysctl_perf_event_paranoid <= 1)
668 return 1;
669 #endif
670 return 0;
671 }
672
673 /*
674 * We show kallsyms information even to normal users if we've enabled
675 * kernel profiling and are explicitly not paranoid (so kptr_restrict
676 * is clear, and sysctl_perf_event_paranoid isn't set).
677 *
678 * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
679 * block even that).
680 */
kallsyms_show_value(const struct cred * cred)681 bool kallsyms_show_value(const struct cred *cred)
682 {
683 switch (kptr_restrict) {
684 case 0:
685 if (kallsyms_for_perf())
686 return true;
687 fallthrough;
688 case 1:
689 if (security_capable(cred, &init_user_ns, CAP_SYSLOG,
690 CAP_OPT_NOAUDIT) == 0)
691 return true;
692 fallthrough;
693 default:
694 return false;
695 }
696 }
697
kallsyms_open(struct inode * inode,struct file * file)698 static int kallsyms_open(struct inode *inode, struct file *file)
699 {
700 /*
701 * We keep iterator in m->private, since normal case is to
702 * s_start from where we left off, so we avoid doing
703 * using get_symbol_offset for every symbol.
704 */
705 struct kallsym_iter *iter;
706 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
707 if (!iter)
708 return -ENOMEM;
709 reset_iter(iter, 0);
710
711 /*
712 * Instead of checking this on every s_show() call, cache
713 * the result here at open time.
714 */
715 iter->show_value = kallsyms_show_value(file->f_cred);
716 return 0;
717 }
718
719 #ifdef CONFIG_KGDB_KDB
kdb_walk_kallsyms(loff_t * pos)720 const char *kdb_walk_kallsyms(loff_t *pos)
721 {
722 static struct kallsym_iter kdb_walk_kallsyms_iter;
723 if (*pos == 0) {
724 memset(&kdb_walk_kallsyms_iter, 0,
725 sizeof(kdb_walk_kallsyms_iter));
726 reset_iter(&kdb_walk_kallsyms_iter, 0);
727 }
728 while (1) {
729 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
730 return NULL;
731 ++*pos;
732 /* Some debugging symbols have no name. Ignore them. */
733 if (kdb_walk_kallsyms_iter.name[0])
734 return kdb_walk_kallsyms_iter.name;
735 }
736 }
737 #endif /* CONFIG_KGDB_KDB */
738
739 static const struct proc_ops kallsyms_proc_ops = {
740 .proc_open = kallsyms_open,
741 .proc_read = seq_read,
742 .proc_lseek = seq_lseek,
743 .proc_release = seq_release_private,
744 };
745
kallsyms_init(void)746 static int __init kallsyms_init(void)
747 {
748 proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
749 return 0;
750 }
751 device_initcall(kallsyms_init);
752
