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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 u8 kallsyms_names[] __weak;
42
43/*
44 * Tell the compiler that the count isn't in the small data section if the arch
45 * has one (eg: FRV).
46 */
47extern const unsigned long kallsyms_num_syms
48__attribute__((weak, section(".rodata")));
49
50extern const u8 kallsyms_token_table[] __weak;
51extern const u16 kallsyms_token_index[] __weak;
52
53extern const unsigned long kallsyms_markers[] __weak;
54
55static inline int is_kernel_inittext(unsigned long addr)
56{
57 if (addr >= (unsigned long)_sinittext
58 && addr <= (unsigned long)_einittext)
59 return 1;
60 return 0;
61}
62
63static inline int is_kernel_text(unsigned long addr)
64{
65 if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) ||
66 arch_is_kernel_text(addr))
67 return 1;
68 return in_gate_area_no_mm(addr);
69}
70
71static inline int is_kernel(unsigned long addr)
72{
73 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
74 return 1;
75 return in_gate_area_no_mm(addr);
76}
77
78static int is_ksym_addr(unsigned long addr)
79{
80 if (all_var)
81 return is_kernel(addr);
82
83 return is_kernel_text(addr) || is_kernel_inittext(addr);
84}
85
86/*
87 * Expand a compressed symbol data into the resulting uncompressed string,
88 * if uncompressed string is too long (>= maxlen), it will be truncated,
89 * given the offset to where the symbol is in the compressed stream.
90 */
91static unsigned int kallsyms_expand_symbol(unsigned int off,
92 char *result, size_t maxlen)
93{
94 int len, skipped_first = 0;
95 const u8 *tptr, *data;
96
97 /* Get the compressed symbol length from the first symbol byte. */
98 data = &kallsyms_names[off];
99 len = *data;
100 data++;
101
102 /*
103 * Update the offset to return the offset for the next symbol on
104 * the compressed stream.
105 */
106 off += len + 1;
107
108 /*
109 * For every byte on the compressed symbol data, copy the table
110 * entry for that byte.
111 */
112 while (len) {
113 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
114 data++;
115 len--;
116
117 while (*tptr) {
118 if (skipped_first) {
119 if (maxlen <= 1)
120 goto tail;
121 *result = *tptr;
122 result++;
123 maxlen--;
124 } else
125 skipped_first = 1;
126 tptr++;
127 }
128 }
129
130tail:
131 if (maxlen)
132 *result = '\0';
133
134 /* Return to offset to the next symbol. */
135 return off;
136}
137
138/*
139 * Get symbol type information. This is encoded as a single char at the
140 * beginning of the symbol name.
141 */
142static char kallsyms_get_symbol_type(unsigned int off)
143{
144 /*
145 * Get just the first code, look it up in the token table,
146 * and return the first char from this token.
147 */
148 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
149}
150
151
152/*
153 * Find the offset on the compressed stream given and index in the
154 * kallsyms array.
155 */
156static unsigned int get_symbol_offset(unsigned long pos)
157{
158 const u8 *name;
159 int i;
160
161 /*
162 * Use the closest marker we have. We have markers every 256 positions,
163 * so that should be close enough.
164 */
165 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
166
167 /*
168 * Sequentially scan all the symbols up to the point we're searching
169 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
170 * so we just need to add the len to the current pointer for every
171 * symbol we wish to skip.
172 */
173 for (i = 0; i < (pos & 0xFF); i++)
174 name = name + (*name) + 1;
175
176 return name - kallsyms_names;
177}
178
179/* Lookup the address for this symbol. Returns 0 if not found. */
180unsigned long kallsyms_lookup_name(const char *name)
181{
182 char namebuf[KSYM_NAME_LEN];
183 unsigned long i;
184 unsigned int off;
185
186 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
187 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
188
189 if (strcmp(namebuf, name) == 0)
190 return kallsyms_addresses[i];
191 }
192 return module_kallsyms_lookup_name(name);
193}
194EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
195
196int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
197 unsigned long),
198 void *data)
199{
200 char namebuf[KSYM_NAME_LEN];
201 unsigned long i;
202 unsigned int off;
203 int ret;
204
205 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
206 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
207 ret = fn(data, namebuf, NULL, kallsyms_addresses[i]);
208 if (ret != 0)
209 return ret;
210 }
211 return module_kallsyms_on_each_symbol(fn, data);
212}
213EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
214
215static unsigned long get_symbol_pos(unsigned long addr,
216 unsigned long *symbolsize,
217 unsigned long *offset)
218{
219 unsigned long symbol_start = 0, symbol_end = 0;
220 unsigned long i, low, high, mid;
221
222 /* This kernel should never had been booted. */
223 BUG_ON(!kallsyms_addresses);
224
225 /* Do a binary search on the sorted kallsyms_addresses array. */
226 low = 0;
227 high = kallsyms_num_syms;
228
229 while (high - low > 1) {
230 mid = low + (high - low) / 2;
231 if (kallsyms_addresses[mid] <= addr)
232 low = mid;
233 else
234 high = mid;
235 }
236
237 /*
238 * Search for the first aliased symbol. Aliased
239 * symbols are symbols with the same address.
240 */
241 while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low])
242 --low;
243
244 symbol_start = kallsyms_addresses[low];
245
246 /* Search for next non-aliased symbol. */
247 for (i = low + 1; i < kallsyms_num_syms; i++) {
248 if (kallsyms_addresses[i] > symbol_start) {
249 symbol_end = kallsyms_addresses[i];
250 break;
251 }
252 }
253
254 /* If we found no next symbol, we use the end of the section. */
255 if (!symbol_end) {
256 if (is_kernel_inittext(addr))
257 symbol_end = (unsigned long)_einittext;
258 else if (all_var)
259 symbol_end = (unsigned long)_end;
260 else
261 symbol_end = (unsigned long)_etext;
262 }
263
264 if (symbolsize)
265 *symbolsize = symbol_end - symbol_start;
266 if (offset)
267 *offset = addr - symbol_start;
268
269 return low;
270}
271
272/*
273 * Lookup an address but don't bother to find any names.
274 */
275int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
276 unsigned long *offset)
277{
278 char namebuf[KSYM_NAME_LEN];
279 if (is_ksym_addr(addr))
280 return !!get_symbol_pos(addr, symbolsize, offset);
281
282 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
283}
284
285/*
286 * Lookup an address
287 * - modname is set to NULL if it's in the kernel.
288 * - We guarantee that the returned name is valid until we reschedule even if.
289 * It resides in a module.
290 * - We also guarantee that modname will be valid until rescheduled.
291 */
292const char *kallsyms_lookup(unsigned long addr,
293 unsigned long *symbolsize,
294 unsigned long *offset,
295 char **modname, char *namebuf)
296{
297 namebuf[KSYM_NAME_LEN - 1] = 0;
298 namebuf[0] = 0;
299
300 if (is_ksym_addr(addr)) {
301 unsigned long pos;
302
303 pos = get_symbol_pos(addr, symbolsize, offset);
304 /* Grab name */
305 kallsyms_expand_symbol(get_symbol_offset(pos),
306 namebuf, KSYM_NAME_LEN);
307 if (modname)
308 *modname = NULL;
309 return namebuf;
310 }
311
312 /* See if it's in a module. */
313 return module_address_lookup(addr, symbolsize, offset, modname,
314 namebuf);
315}
316
317int lookup_symbol_name(unsigned long addr, char *symname)
318{
319 symname[0] = '\0';
320 symname[KSYM_NAME_LEN - 1] = '\0';
321
322 if (is_ksym_addr(addr)) {
323 unsigned long pos;
324
325 pos = get_symbol_pos(addr, NULL, NULL);
326 /* Grab name */
327 kallsyms_expand_symbol(get_symbol_offset(pos),
328 symname, KSYM_NAME_LEN);
329 return 0;
330 }
331 /* See if it's in a module. */
332 return lookup_module_symbol_name(addr, symname);
333}
334
335int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
336 unsigned long *offset, char *modname, char *name)
337{
338 name[0] = '\0';
339 name[KSYM_NAME_LEN - 1] = '\0';
340
341 if (is_ksym_addr(addr)) {
342 unsigned long pos;
343
344 pos = get_symbol_pos(addr, size, offset);
345 /* Grab name */
346 kallsyms_expand_symbol(get_symbol_offset(pos),
347 name, KSYM_NAME_LEN);
348 modname[0] = '\0';
349 return 0;
350 }
351 /* See if it's in a module. */
352 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
353}
354
355/* Look up a kernel symbol and return it in a text buffer. */
356static int __sprint_symbol(char *buffer, unsigned long address,
357 int symbol_offset, int add_offset)
358{
359 char *modname;
360 const char *name;
361 unsigned long offset, size;
362 int len;
363
364 address += symbol_offset;
365 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
366 if (!name)
367 return sprintf(buffer, "0x%lx", address);
368
369 if (name != buffer)
370 strcpy(buffer, name);
371 len = strlen(buffer);
372 offset -= symbol_offset;
373
374 if (add_offset)
375 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
376
377 if (modname)
378 len += sprintf(buffer + len, " [%s]", modname);
379
380 return len;
381}
382
383/**
384 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
385 * @buffer: buffer to be stored
386 * @address: address to lookup
387 *
388 * This function looks up a kernel symbol with @address and stores its name,
389 * offset, size and module name to @buffer if possible. If no symbol was found,
390 * just saves its @address as is.
391 *
392 * This function returns the number of bytes stored in @buffer.
393 */
394int sprint_symbol(char *buffer, unsigned long address)
395{
396 return __sprint_symbol(buffer, address, 0, 1);
397}
398EXPORT_SYMBOL_GPL(sprint_symbol);
399
400/**
401 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
402 * @buffer: buffer to be stored
403 * @address: address to lookup
404 *
405 * This function looks up a kernel symbol with @address and stores its name
406 * and module name to @buffer if possible. If no symbol was found, just saves
407 * its @address as is.
408 *
409 * This function returns the number of bytes stored in @buffer.
410 */
411int sprint_symbol_no_offset(char *buffer, unsigned long address)
412{
413 return __sprint_symbol(buffer, address, 0, 0);
414}
415EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
416
417/**
418 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
419 * @buffer: buffer to be stored
420 * @address: address to lookup
421 *
422 * This function is for stack backtrace and does the same thing as
423 * sprint_symbol() but with modified/decreased @address. If there is a
424 * tail-call to the function marked "noreturn", gcc optimized out code after
425 * the call so that the stack-saved return address could point outside of the
426 * caller. This function ensures that kallsyms will find the original caller
427 * by decreasing @address.
428 *
429 * This function returns the number of bytes stored in @buffer.
430 */
431int sprint_backtrace(char *buffer, unsigned long address)
432{
433 return __sprint_symbol(buffer, address, -1, 1);
434}
435
436/* Look up a kernel symbol and print it to the kernel messages. */
437void __print_symbol(const char *fmt, unsigned long address)
438{
439 char buffer[KSYM_SYMBOL_LEN];
440
441 sprint_symbol(buffer, address);
442
443 printk(fmt, buffer);
444}
445EXPORT_SYMBOL(__print_symbol);
446
447/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
448struct kallsym_iter {
449 loff_t pos;
450 unsigned long value;
451 unsigned int nameoff; /* If iterating in core kernel symbols. */
452 char type;
453 char name[KSYM_NAME_LEN];
454 char module_name[MODULE_NAME_LEN];
455 int exported;
456};
457
458static int get_ksymbol_mod(struct kallsym_iter *iter)
459{
460 if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
461 &iter->type, iter->name, iter->module_name,
462 &iter->exported) < 0)
463 return 0;
464 return 1;
465}
466
467/* Returns space to next name. */
468static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
469{
470 unsigned off = iter->nameoff;
471
472 iter->module_name[0] = '\0';
473 iter->value = kallsyms_addresses[iter->pos];
474
475 iter->type = kallsyms_get_symbol_type(off);
476
477 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
478
479 return off - iter->nameoff;
480}
481
482static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
483{
484 iter->name[0] = '\0';
485 iter->nameoff = get_symbol_offset(new_pos);
486 iter->pos = new_pos;
487}
488
489/* Returns false if pos at or past end of file. */
490static int update_iter(struct kallsym_iter *iter, loff_t pos)
491{
492 /* Module symbols can be accessed randomly. */
493 if (pos >= kallsyms_num_syms) {
494 iter->pos = pos;
495 return get_ksymbol_mod(iter);
496 }
497
498 /* If we're not on the desired position, reset to new position. */
499 if (pos != iter->pos)
500 reset_iter(iter, pos);
501
502 iter->nameoff += get_ksymbol_core(iter);
503 iter->pos++;
504
505 return 1;
506}
507
508static void *s_next(struct seq_file *m, void *p, loff_t *pos)
509{
510 (*pos)++;
511
512 if (!update_iter(m->private, *pos))
513 return NULL;
514 return p;
515}
516
517static void *s_start(struct seq_file *m, loff_t *pos)
518{
519 if (!update_iter(m->private, *pos))
520 return NULL;
521 return m->private;
522}
523
524static void s_stop(struct seq_file *m, void *p)
525{
526}
527
528static int s_show(struct seq_file *m, void *p)
529{
530 struct kallsym_iter *iter = m->private;
531
532 /* Some debugging symbols have no name. Ignore them. */
533 if (!iter->name[0])
534 return 0;
535
536 if (iter->module_name[0]) {
537 char type;
538
539 /*
540 * Label it "global" if it is exported,
541 * "local" if not exported.
542 */
543 type = iter->exported ? toupper(iter->type) :
544 tolower(iter->type);
545 seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
546 type, iter->name, iter->module_name);
547 } else
548 seq_printf(m, "%pK %c %s\n", (void *)iter->value,
549 iter->type, iter->name);
550 return 0;
551}
552
553static const struct seq_operations kallsyms_op = {
554 .start = s_start,
555 .next = s_next,
556 .stop = s_stop,
557 .show = s_show
558};
559
560static int kallsyms_open(struct inode *inode, struct file *file)
561{
562 /*
563 * We keep iterator in m->private, since normal case is to
564 * s_start from where we left off, so we avoid doing
565 * using get_symbol_offset for every symbol.
566 */
567 struct kallsym_iter *iter;
568 int ret;
569
570 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
571 if (!iter)
572 return -ENOMEM;
573 reset_iter(iter, 0);
574
575 ret = seq_open(file, &kallsyms_op);
576 if (ret == 0)
577 ((struct seq_file *)file->private_data)->private = iter;
578 else
579 kfree(iter);
580 return ret;
581}
582
583#ifdef CONFIG_KGDB_KDB
584const char *kdb_walk_kallsyms(loff_t *pos)
585{
586 static struct kallsym_iter kdb_walk_kallsyms_iter;
587 if (*pos == 0) {
588 memset(&kdb_walk_kallsyms_iter, 0,
589 sizeof(kdb_walk_kallsyms_iter));
590 reset_iter(&kdb_walk_kallsyms_iter, 0);
591 }
592 while (1) {
593 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
594 return NULL;
595 ++*pos;
596 /* Some debugging symbols have no name. Ignore them. */
597 if (kdb_walk_kallsyms_iter.name[0])
598 return kdb_walk_kallsyms_iter.name;
599 }
600}
601#endif /* CONFIG_KGDB_KDB */
602
603static const struct file_operations kallsyms_operations = {
604 .open = kallsyms_open,
605 .read = seq_read,
606 .llseek = seq_lseek,
607 .release = seq_release_private,
608};
609
610static int __init kallsyms_init(void)
611{
612 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
613 return 0;
614}
615device_initcall(kallsyms_init);
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/build_bug.h>
29#include <linux/compiler.h>
30#include <linux/module.h>
31#include <linux/kernel.h>
32#include <linux/bsearch.h>
33#include <linux/btf_ids.h>
34
35#include "kallsyms_internal.h"
36
37/*
38 * Expand a compressed symbol data into the resulting uncompressed string,
39 * if uncompressed string is too long (>= maxlen), it will be truncated,
40 * given the offset to where the symbol is in the compressed stream.
41 */
42static unsigned int kallsyms_expand_symbol(unsigned int off,
43 char *result, size_t maxlen)
44{
45 int len, skipped_first = 0;
46 const char *tptr;
47 const u8 *data;
48
49 /* Get the compressed symbol length from the first symbol byte. */
50 data = &kallsyms_names[off];
51 len = *data;
52 data++;
53 off++;
54
55 /* If MSB is 1, it is a "big" symbol, so needs an additional byte. */
56 if ((len & 0x80) != 0) {
57 len = (len & 0x7F) | (*data << 7);
58 data++;
59 off++;
60 }
61
62 /*
63 * Update the offset to return the offset for the next symbol on
64 * the compressed stream.
65 */
66 off += len;
67
68 /*
69 * For every byte on the compressed symbol data, copy the table
70 * entry for that byte.
71 */
72 while (len) {
73 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
74 data++;
75 len--;
76
77 while (*tptr) {
78 if (skipped_first) {
79 if (maxlen <= 1)
80 goto tail;
81 *result = *tptr;
82 result++;
83 maxlen--;
84 } else
85 skipped_first = 1;
86 tptr++;
87 }
88 }
89
90tail:
91 if (maxlen)
92 *result = '\0';
93
94 /* Return to offset to the next symbol. */
95 return off;
96}
97
98/*
99 * Get symbol type information. This is encoded as a single char at the
100 * beginning of the symbol name.
101 */
102static char kallsyms_get_symbol_type(unsigned int off)
103{
104 /*
105 * Get just the first code, look it up in the token table,
106 * and return the first char from this token.
107 */
108 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
109}
110
111
112/*
113 * Find the offset on the compressed stream given and index in the
114 * kallsyms array.
115 */
116static unsigned int get_symbol_offset(unsigned long pos)
117{
118 const u8 *name;
119 int i, len;
120
121 /*
122 * Use the closest marker we have. We have markers every 256 positions,
123 * so that should be close enough.
124 */
125 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
126
127 /*
128 * Sequentially scan all the symbols up to the point we're searching
129 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
130 * so we just need to add the len to the current pointer for every
131 * symbol we wish to skip.
132 */
133 for (i = 0; i < (pos & 0xFF); i++) {
134 len = *name;
135
136 /*
137 * If MSB is 1, it is a "big" symbol, so we need to look into
138 * the next byte (and skip it, too).
139 */
140 if ((len & 0x80) != 0)
141 len = ((len & 0x7F) | (name[1] << 7)) + 1;
142
143 name = name + len + 1;
144 }
145
146 return name - kallsyms_names;
147}
148
149unsigned long kallsyms_sym_address(int idx)
150{
151 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
152 return kallsyms_addresses[idx];
153
154 /* values are unsigned offsets if --absolute-percpu is not in effect */
155 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
156 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
157
158 /* ...otherwise, positive offsets are absolute values */
159 if (kallsyms_offsets[idx] >= 0)
160 return kallsyms_offsets[idx];
161
162 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
163 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
164}
165
166static void cleanup_symbol_name(char *s)
167{
168 char *res;
169
170 if (!IS_ENABLED(CONFIG_LTO_CLANG))
171 return;
172
173 /*
174 * LLVM appends various suffixes for local functions and variables that
175 * must be promoted to global scope as part of LTO. This can break
176 * hooking of static functions with kprobes. '.' is not a valid
177 * character in an identifier in C. Suffixes only in LLVM LTO observed:
178 * - foo.llvm.[0-9a-f]+
179 */
180 res = strstr(s, ".llvm.");
181 if (res)
182 *res = '\0';
183
184 return;
185}
186
187static int compare_symbol_name(const char *name, char *namebuf)
188{
189 /* The kallsyms_seqs_of_names is sorted based on names after
190 * cleanup_symbol_name() (see scripts/kallsyms.c) if clang lto is enabled.
191 * To ensure correct bisection in kallsyms_lookup_names(), do
192 * cleanup_symbol_name(namebuf) before comparing name and namebuf.
193 */
194 cleanup_symbol_name(namebuf);
195 return strcmp(name, namebuf);
196}
197
198static unsigned int get_symbol_seq(int index)
199{
200 unsigned int i, seq = 0;
201
202 for (i = 0; i < 3; i++)
203 seq = (seq << 8) | kallsyms_seqs_of_names[3 * index + i];
204
205 return seq;
206}
207
208static int kallsyms_lookup_names(const char *name,
209 unsigned int *start,
210 unsigned int *end)
211{
212 int ret;
213 int low, mid, high;
214 unsigned int seq, off;
215 char namebuf[KSYM_NAME_LEN];
216
217 low = 0;
218 high = kallsyms_num_syms - 1;
219
220 while (low <= high) {
221 mid = low + (high - low) / 2;
222 seq = get_symbol_seq(mid);
223 off = get_symbol_offset(seq);
224 kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
225 ret = compare_symbol_name(name, namebuf);
226 if (ret > 0)
227 low = mid + 1;
228 else if (ret < 0)
229 high = mid - 1;
230 else
231 break;
232 }
233
234 if (low > high)
235 return -ESRCH;
236
237 low = mid;
238 while (low) {
239 seq = get_symbol_seq(low - 1);
240 off = get_symbol_offset(seq);
241 kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
242 if (compare_symbol_name(name, namebuf))
243 break;
244 low--;
245 }
246 *start = low;
247
248 if (end) {
249 high = mid;
250 while (high < kallsyms_num_syms - 1) {
251 seq = get_symbol_seq(high + 1);
252 off = get_symbol_offset(seq);
253 kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
254 if (compare_symbol_name(name, namebuf))
255 break;
256 high++;
257 }
258 *end = high;
259 }
260
261 return 0;
262}
263
264/* Lookup the address for this symbol. Returns 0 if not found. */
265unsigned long kallsyms_lookup_name(const char *name)
266{
267 int ret;
268 unsigned int i;
269
270 /* Skip the search for empty string. */
271 if (!*name)
272 return 0;
273
274 ret = kallsyms_lookup_names(name, &i, NULL);
275 if (!ret)
276 return kallsyms_sym_address(get_symbol_seq(i));
277
278 return module_kallsyms_lookup_name(name);
279}
280
281/*
282 * Iterate over all symbols in vmlinux. For symbols from modules use
283 * module_kallsyms_on_each_symbol instead.
284 */
285int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long),
286 void *data)
287{
288 char namebuf[KSYM_NAME_LEN];
289 unsigned long i;
290 unsigned int off;
291 int ret;
292
293 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
294 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
295 ret = fn(data, namebuf, kallsyms_sym_address(i));
296 if (ret != 0)
297 return ret;
298 cond_resched();
299 }
300 return 0;
301}
302
303int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long),
304 const char *name, void *data)
305{
306 int ret;
307 unsigned int i, start, end;
308
309 ret = kallsyms_lookup_names(name, &start, &end);
310 if (ret)
311 return 0;
312
313 for (i = start; !ret && i <= end; i++) {
314 ret = fn(data, kallsyms_sym_address(get_symbol_seq(i)));
315 cond_resched();
316 }
317
318 return ret;
319}
320
321static unsigned long get_symbol_pos(unsigned long addr,
322 unsigned long *symbolsize,
323 unsigned long *offset)
324{
325 unsigned long symbol_start = 0, symbol_end = 0;
326 unsigned long i, low, high, mid;
327
328 /* This kernel should never had been booted. */
329 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
330 BUG_ON(!kallsyms_addresses);
331 else
332 BUG_ON(!kallsyms_offsets);
333
334 /* Do a binary search on the sorted kallsyms_addresses array. */
335 low = 0;
336 high = kallsyms_num_syms;
337
338 while (high - low > 1) {
339 mid = low + (high - low) / 2;
340 if (kallsyms_sym_address(mid) <= addr)
341 low = mid;
342 else
343 high = mid;
344 }
345
346 /*
347 * Search for the first aliased symbol. Aliased
348 * symbols are symbols with the same address.
349 */
350 while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
351 --low;
352
353 symbol_start = kallsyms_sym_address(low);
354
355 /* Search for next non-aliased symbol. */
356 for (i = low + 1; i < kallsyms_num_syms; i++) {
357 if (kallsyms_sym_address(i) > symbol_start) {
358 symbol_end = kallsyms_sym_address(i);
359 break;
360 }
361 }
362
363 /* If we found no next symbol, we use the end of the section. */
364 if (!symbol_end) {
365 if (is_kernel_inittext(addr))
366 symbol_end = (unsigned long)_einittext;
367 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
368 symbol_end = (unsigned long)_end;
369 else
370 symbol_end = (unsigned long)_etext;
371 }
372
373 if (symbolsize)
374 *symbolsize = symbol_end - symbol_start;
375 if (offset)
376 *offset = addr - symbol_start;
377
378 return low;
379}
380
381/*
382 * Lookup an address but don't bother to find any names.
383 */
384int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
385 unsigned long *offset)
386{
387 char namebuf[KSYM_NAME_LEN];
388
389 if (is_ksym_addr(addr)) {
390 get_symbol_pos(addr, symbolsize, offset);
391 return 1;
392 }
393 return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) ||
394 !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
395}
396
397static const char *kallsyms_lookup_buildid(unsigned long addr,
398 unsigned long *symbolsize,
399 unsigned long *offset, char **modname,
400 const unsigned char **modbuildid, char *namebuf)
401{
402 const char *ret;
403
404 namebuf[KSYM_NAME_LEN - 1] = 0;
405 namebuf[0] = 0;
406
407 if (is_ksym_addr(addr)) {
408 unsigned long pos;
409
410 pos = get_symbol_pos(addr, symbolsize, offset);
411 /* Grab name */
412 kallsyms_expand_symbol(get_symbol_offset(pos),
413 namebuf, KSYM_NAME_LEN);
414 if (modname)
415 *modname = NULL;
416 if (modbuildid)
417 *modbuildid = NULL;
418
419 ret = namebuf;
420 goto found;
421 }
422
423 /* See if it's in a module or a BPF JITed image. */
424 ret = module_address_lookup(addr, symbolsize, offset,
425 modname, modbuildid, namebuf);
426 if (!ret)
427 ret = bpf_address_lookup(addr, symbolsize,
428 offset, modname, namebuf);
429
430 if (!ret)
431 ret = ftrace_mod_address_lookup(addr, symbolsize,
432 offset, modname, namebuf);
433
434found:
435 cleanup_symbol_name(namebuf);
436 return ret;
437}
438
439/*
440 * Lookup an address
441 * - modname is set to NULL if it's in the kernel.
442 * - We guarantee that the returned name is valid until we reschedule even if.
443 * It resides in a module.
444 * - We also guarantee that modname will be valid until rescheduled.
445 */
446const char *kallsyms_lookup(unsigned long addr,
447 unsigned long *symbolsize,
448 unsigned long *offset,
449 char **modname, char *namebuf)
450{
451 return kallsyms_lookup_buildid(addr, symbolsize, offset, modname,
452 NULL, namebuf);
453}
454
455int lookup_symbol_name(unsigned long addr, char *symname)
456{
457 int res;
458
459 symname[0] = '\0';
460 symname[KSYM_NAME_LEN - 1] = '\0';
461
462 if (is_ksym_addr(addr)) {
463 unsigned long pos;
464
465 pos = get_symbol_pos(addr, NULL, NULL);
466 /* Grab name */
467 kallsyms_expand_symbol(get_symbol_offset(pos),
468 symname, KSYM_NAME_LEN);
469 goto found;
470 }
471 /* See if it's in a module. */
472 res = lookup_module_symbol_name(addr, symname);
473 if (res)
474 return res;
475
476found:
477 cleanup_symbol_name(symname);
478 return 0;
479}
480
481/* Look up a kernel symbol and return it in a text buffer. */
482static int __sprint_symbol(char *buffer, unsigned long address,
483 int symbol_offset, int add_offset, int add_buildid)
484{
485 char *modname;
486 const unsigned char *buildid;
487 const char *name;
488 unsigned long offset, size;
489 int len;
490
491 address += symbol_offset;
492 name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid,
493 buffer);
494 if (!name)
495 return sprintf(buffer, "0x%lx", address - symbol_offset);
496
497 if (name != buffer)
498 strcpy(buffer, name);
499 len = strlen(buffer);
500 offset -= symbol_offset;
501
502 if (add_offset)
503 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
504
505 if (modname) {
506 len += sprintf(buffer + len, " [%s", modname);
507#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
508 if (add_buildid && buildid) {
509 /* build ID should match length of sprintf */
510#if IS_ENABLED(CONFIG_MODULES)
511 static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
512#endif
513 len += sprintf(buffer + len, " %20phN", buildid);
514 }
515#endif
516 len += sprintf(buffer + len, "]");
517 }
518
519 return len;
520}
521
522/**
523 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
524 * @buffer: buffer to be stored
525 * @address: address to lookup
526 *
527 * This function looks up a kernel symbol with @address and stores its name,
528 * offset, size and module name to @buffer if possible. If no symbol was found,
529 * just saves its @address as is.
530 *
531 * This function returns the number of bytes stored in @buffer.
532 */
533int sprint_symbol(char *buffer, unsigned long address)
534{
535 return __sprint_symbol(buffer, address, 0, 1, 0);
536}
537EXPORT_SYMBOL_GPL(sprint_symbol);
538
539/**
540 * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
541 * @buffer: buffer to be stored
542 * @address: address to lookup
543 *
544 * This function looks up a kernel symbol with @address and stores its name,
545 * offset, size, module name and module build ID to @buffer if possible. If no
546 * symbol was found, just saves its @address as is.
547 *
548 * This function returns the number of bytes stored in @buffer.
549 */
550int sprint_symbol_build_id(char *buffer, unsigned long address)
551{
552 return __sprint_symbol(buffer, address, 0, 1, 1);
553}
554EXPORT_SYMBOL_GPL(sprint_symbol_build_id);
555
556/**
557 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
558 * @buffer: buffer to be stored
559 * @address: address to lookup
560 *
561 * This function looks up a kernel symbol with @address and stores its name
562 * and module name to @buffer if possible. If no symbol was found, just saves
563 * its @address as is.
564 *
565 * This function returns the number of bytes stored in @buffer.
566 */
567int sprint_symbol_no_offset(char *buffer, unsigned long address)
568{
569 return __sprint_symbol(buffer, address, 0, 0, 0);
570}
571EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
572
573/**
574 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
575 * @buffer: buffer to be stored
576 * @address: address to lookup
577 *
578 * This function is for stack backtrace and does the same thing as
579 * sprint_symbol() but with modified/decreased @address. If there is a
580 * tail-call to the function marked "noreturn", gcc optimized out code after
581 * the call so that the stack-saved return address could point outside of the
582 * caller. This function ensures that kallsyms will find the original caller
583 * by decreasing @address.
584 *
585 * This function returns the number of bytes stored in @buffer.
586 */
587int sprint_backtrace(char *buffer, unsigned long address)
588{
589 return __sprint_symbol(buffer, address, -1, 1, 0);
590}
591
592/**
593 * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
594 * @buffer: buffer to be stored
595 * @address: address to lookup
596 *
597 * This function is for stack backtrace and does the same thing as
598 * sprint_symbol() but with modified/decreased @address. If there is a
599 * tail-call to the function marked "noreturn", gcc optimized out code after
600 * the call so that the stack-saved return address could point outside of the
601 * caller. This function ensures that kallsyms will find the original caller
602 * by decreasing @address. This function also appends the module build ID to
603 * the @buffer if @address is within a kernel module.
604 *
605 * This function returns the number of bytes stored in @buffer.
606 */
607int sprint_backtrace_build_id(char *buffer, unsigned long address)
608{
609 return __sprint_symbol(buffer, address, -1, 1, 1);
610}
611
612/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
613struct kallsym_iter {
614 loff_t pos;
615 loff_t pos_mod_end;
616 loff_t pos_ftrace_mod_end;
617 loff_t pos_bpf_end;
618 unsigned long value;
619 unsigned int nameoff; /* If iterating in core kernel symbols. */
620 char type;
621 char name[KSYM_NAME_LEN];
622 char module_name[MODULE_NAME_LEN];
623 int exported;
624 int show_value;
625};
626
627static int get_ksymbol_mod(struct kallsym_iter *iter)
628{
629 int ret = module_get_kallsym(iter->pos - kallsyms_num_syms,
630 &iter->value, &iter->type,
631 iter->name, iter->module_name,
632 &iter->exported);
633 if (ret < 0) {
634 iter->pos_mod_end = iter->pos;
635 return 0;
636 }
637
638 return 1;
639}
640
641/*
642 * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
643 * purposes. In that case "__builtin__ftrace" is used as a module name, even
644 * though "__builtin__ftrace" is not a module.
645 */
646static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
647{
648 int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
649 &iter->value, &iter->type,
650 iter->name, iter->module_name,
651 &iter->exported);
652 if (ret < 0) {
653 iter->pos_ftrace_mod_end = iter->pos;
654 return 0;
655 }
656
657 return 1;
658}
659
660static int get_ksymbol_bpf(struct kallsym_iter *iter)
661{
662 int ret;
663
664 strscpy(iter->module_name, "bpf", MODULE_NAME_LEN);
665 iter->exported = 0;
666 ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
667 &iter->value, &iter->type,
668 iter->name);
669 if (ret < 0) {
670 iter->pos_bpf_end = iter->pos;
671 return 0;
672 }
673
674 return 1;
675}
676
677/*
678 * This uses "__builtin__kprobes" as a module name for symbols for pages
679 * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
680 * module.
681 */
682static int get_ksymbol_kprobe(struct kallsym_iter *iter)
683{
684 strscpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
685 iter->exported = 0;
686 return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
687 &iter->value, &iter->type,
688 iter->name) < 0 ? 0 : 1;
689}
690
691/* Returns space to next name. */
692static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
693{
694 unsigned off = iter->nameoff;
695
696 iter->module_name[0] = '\0';
697 iter->value = kallsyms_sym_address(iter->pos);
698
699 iter->type = kallsyms_get_symbol_type(off);
700
701 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
702
703 return off - iter->nameoff;
704}
705
706static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
707{
708 iter->name[0] = '\0';
709 iter->nameoff = get_symbol_offset(new_pos);
710 iter->pos = new_pos;
711 if (new_pos == 0) {
712 iter->pos_mod_end = 0;
713 iter->pos_ftrace_mod_end = 0;
714 iter->pos_bpf_end = 0;
715 }
716}
717
718/*
719 * The end position (last + 1) of each additional kallsyms section is recorded
720 * in iter->pos_..._end as each section is added, and so can be used to
721 * determine which get_ksymbol_...() function to call next.
722 */
723static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
724{
725 iter->pos = pos;
726
727 if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
728 get_ksymbol_mod(iter))
729 return 1;
730
731 if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
732 get_ksymbol_ftrace_mod(iter))
733 return 1;
734
735 if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
736 get_ksymbol_bpf(iter))
737 return 1;
738
739 return get_ksymbol_kprobe(iter);
740}
741
742/* Returns false if pos at or past end of file. */
743static int update_iter(struct kallsym_iter *iter, loff_t pos)
744{
745 /* Module symbols can be accessed randomly. */
746 if (pos >= kallsyms_num_syms)
747 return update_iter_mod(iter, pos);
748
749 /* If we're not on the desired position, reset to new position. */
750 if (pos != iter->pos)
751 reset_iter(iter, pos);
752
753 iter->nameoff += get_ksymbol_core(iter);
754 iter->pos++;
755
756 return 1;
757}
758
759static void *s_next(struct seq_file *m, void *p, loff_t *pos)
760{
761 (*pos)++;
762
763 if (!update_iter(m->private, *pos))
764 return NULL;
765 return p;
766}
767
768static void *s_start(struct seq_file *m, loff_t *pos)
769{
770 if (!update_iter(m->private, *pos))
771 return NULL;
772 return m->private;
773}
774
775static void s_stop(struct seq_file *m, void *p)
776{
777}
778
779static int s_show(struct seq_file *m, void *p)
780{
781 void *value;
782 struct kallsym_iter *iter = m->private;
783
784 /* Some debugging symbols have no name. Ignore them. */
785 if (!iter->name[0])
786 return 0;
787
788 value = iter->show_value ? (void *)iter->value : NULL;
789
790 if (iter->module_name[0]) {
791 char type;
792
793 /*
794 * Label it "global" if it is exported,
795 * "local" if not exported.
796 */
797 type = iter->exported ? toupper(iter->type) :
798 tolower(iter->type);
799 seq_printf(m, "%px %c %s\t[%s]\n", value,
800 type, iter->name, iter->module_name);
801 } else
802 seq_printf(m, "%px %c %s\n", value,
803 iter->type, iter->name);
804 return 0;
805}
806
807static const struct seq_operations kallsyms_op = {
808 .start = s_start,
809 .next = s_next,
810 .stop = s_stop,
811 .show = s_show
812};
813
814#ifdef CONFIG_BPF_SYSCALL
815
816struct bpf_iter__ksym {
817 __bpf_md_ptr(struct bpf_iter_meta *, meta);
818 __bpf_md_ptr(struct kallsym_iter *, ksym);
819};
820
821static int ksym_prog_seq_show(struct seq_file *m, bool in_stop)
822{
823 struct bpf_iter__ksym ctx;
824 struct bpf_iter_meta meta;
825 struct bpf_prog *prog;
826
827 meta.seq = m;
828 prog = bpf_iter_get_info(&meta, in_stop);
829 if (!prog)
830 return 0;
831
832 ctx.meta = &meta;
833 ctx.ksym = m ? m->private : NULL;
834 return bpf_iter_run_prog(prog, &ctx);
835}
836
837static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p)
838{
839 return ksym_prog_seq_show(m, false);
840}
841
842static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p)
843{
844 if (!p)
845 (void) ksym_prog_seq_show(m, true);
846 else
847 s_stop(m, p);
848}
849
850static const struct seq_operations bpf_iter_ksym_ops = {
851 .start = s_start,
852 .next = s_next,
853 .stop = bpf_iter_ksym_seq_stop,
854 .show = bpf_iter_ksym_seq_show,
855};
856
857static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux)
858{
859 struct kallsym_iter *iter = priv_data;
860
861 reset_iter(iter, 0);
862
863 /* cache here as in kallsyms_open() case; use current process
864 * credentials to tell BPF iterators if values should be shown.
865 */
866 iter->show_value = kallsyms_show_value(current_cred());
867
868 return 0;
869}
870
871DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym)
872
873static const struct bpf_iter_seq_info ksym_iter_seq_info = {
874 .seq_ops = &bpf_iter_ksym_ops,
875 .init_seq_private = bpf_iter_ksym_init,
876 .fini_seq_private = NULL,
877 .seq_priv_size = sizeof(struct kallsym_iter),
878};
879
880static struct bpf_iter_reg ksym_iter_reg_info = {
881 .target = "ksym",
882 .feature = BPF_ITER_RESCHED,
883 .ctx_arg_info_size = 1,
884 .ctx_arg_info = {
885 { offsetof(struct bpf_iter__ksym, ksym),
886 PTR_TO_BTF_ID_OR_NULL },
887 },
888 .seq_info = &ksym_iter_seq_info,
889};
890
891BTF_ID_LIST(btf_ksym_iter_id)
892BTF_ID(struct, kallsym_iter)
893
894static int __init bpf_ksym_iter_register(void)
895{
896 ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id;
897 return bpf_iter_reg_target(&ksym_iter_reg_info);
898}
899
900late_initcall(bpf_ksym_iter_register);
901
902#endif /* CONFIG_BPF_SYSCALL */
903
904static int kallsyms_open(struct inode *inode, struct file *file)
905{
906 /*
907 * We keep iterator in m->private, since normal case is to
908 * s_start from where we left off, so we avoid doing
909 * using get_symbol_offset for every symbol.
910 */
911 struct kallsym_iter *iter;
912 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
913 if (!iter)
914 return -ENOMEM;
915 reset_iter(iter, 0);
916
917 /*
918 * Instead of checking this on every s_show() call, cache
919 * the result here at open time.
920 */
921 iter->show_value = kallsyms_show_value(file->f_cred);
922 return 0;
923}
924
925#ifdef CONFIG_KGDB_KDB
926const char *kdb_walk_kallsyms(loff_t *pos)
927{
928 static struct kallsym_iter kdb_walk_kallsyms_iter;
929 if (*pos == 0) {
930 memset(&kdb_walk_kallsyms_iter, 0,
931 sizeof(kdb_walk_kallsyms_iter));
932 reset_iter(&kdb_walk_kallsyms_iter, 0);
933 }
934 while (1) {
935 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
936 return NULL;
937 ++*pos;
938 /* Some debugging symbols have no name. Ignore them. */
939 if (kdb_walk_kallsyms_iter.name[0])
940 return kdb_walk_kallsyms_iter.name;
941 }
942}
943#endif /* CONFIG_KGDB_KDB */
944
945static const struct proc_ops kallsyms_proc_ops = {
946 .proc_open = kallsyms_open,
947 .proc_read = seq_read,
948 .proc_lseek = seq_lseek,
949 .proc_release = seq_release_private,
950};
951
952static int __init kallsyms_init(void)
953{
954 proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
955 return 0;
956}
957device_initcall(kallsyms_init);