1 // SPDX-License-Identifier: GPL-2.0-only
3 * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
5 * Rewritten and vastly simplified by Rusty Russell for in-kernel
7 * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
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)
15 #include <linux/kallsyms.h>
16 #include <linux/init.h>
17 #include <linux/seq_file.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>
35 #include "kallsyms_internal.h"
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.
42 static unsigned int kallsyms_expand_symbol(unsigned int off,
43 char *result, size_t maxlen)
45 int len, skipped_first = 0;
49 /* Get the compressed symbol length from the first symbol byte. */
50 data = &kallsyms_names[off];
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);
63 * Update the offset to return the offset for the next symbol on
64 * the compressed stream.
69 * For every byte on the compressed symbol data, copy the table
70 * entry for that byte.
73 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
94 /* Return to offset to the next symbol. */
99 * Get symbol type information. This is encoded as a single char at the
100 * beginning of the symbol name.
102 static char kallsyms_get_symbol_type(unsigned int off)
105 * Get just the first code, look it up in the token table,
106 * and return the first char from this token.
108 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
113 * Find the offset on the compressed stream given and index in the
116 static unsigned int get_symbol_offset(unsigned long pos)
122 * Use the closest marker we have. We have markers every 256 positions,
123 * so that should be close enough.
125 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
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.
133 for (i = 0; i < (pos & 0xFF); i++) {
137 * If MSB is 1, it is a "big" symbol, so we need to look into
138 * the next byte (and skip it, too).
140 if ((len & 0x80) != 0)
141 len = ((len & 0x7F) | (name[1] << 7)) + 1;
143 name = name + len + 1;
146 return name - kallsyms_names;
149 static unsigned long kallsyms_sym_address(int idx)
151 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
152 return kallsyms_addresses[idx];
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];
158 /* ...otherwise, positive offsets are absolute values */
159 if (kallsyms_offsets[idx] >= 0)
160 return kallsyms_offsets[idx];
162 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
163 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
166 static bool cleanup_symbol_name(char *s)
170 if (!IS_ENABLED(CONFIG_LTO_CLANG))
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]+
180 res = strstr(s, ".llvm.");
189 static int compare_symbol_name(const char *name, char *namebuf)
191 /* The kallsyms_seqs_of_names is sorted based on names after
192 * cleanup_symbol_name() (see scripts/kallsyms.c) if clang lto is enabled.
193 * To ensure correct bisection in kallsyms_lookup_names(), do
194 * cleanup_symbol_name(namebuf) before comparing name and namebuf.
196 cleanup_symbol_name(namebuf);
197 return strcmp(name, namebuf);
200 static int kallsyms_lookup_names(const char *name,
206 unsigned int seq, off;
207 char namebuf[KSYM_NAME_LEN];
210 high = kallsyms_num_syms - 1;
212 while (low <= high) {
213 mid = low + (high - low) / 2;
214 seq = kallsyms_seqs_of_names[mid];
215 off = get_symbol_offset(seq);
216 kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
217 ret = compare_symbol_name(name, namebuf);
231 seq = kallsyms_seqs_of_names[low - 1];
232 off = get_symbol_offset(seq);
233 kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
234 if (compare_symbol_name(name, namebuf))
242 while (high < kallsyms_num_syms - 1) {
243 seq = kallsyms_seqs_of_names[high + 1];
244 off = get_symbol_offset(seq);
245 kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
246 if (compare_symbol_name(name, namebuf))
256 /* Lookup the address for this symbol. Returns 0 if not found. */
257 unsigned long kallsyms_lookup_name(const char *name)
262 /* Skip the search for empty string. */
266 ret = kallsyms_lookup_names(name, &i, NULL);
268 return kallsyms_sym_address(kallsyms_seqs_of_names[i]);
270 return module_kallsyms_lookup_name(name);
274 * Iterate over all symbols in vmlinux. For symbols from modules use
275 * module_kallsyms_on_each_symbol instead.
277 int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
281 char namebuf[KSYM_NAME_LEN];
286 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
287 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
288 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
296 static unsigned long get_symbol_pos(unsigned long addr,
297 unsigned long *symbolsize,
298 unsigned long *offset)
300 unsigned long symbol_start = 0, symbol_end = 0;
301 unsigned long i, low, high, mid;
303 /* This kernel should never had been booted. */
304 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
305 BUG_ON(!kallsyms_addresses);
307 BUG_ON(!kallsyms_offsets);
309 /* Do a binary search on the sorted kallsyms_addresses array. */
311 high = kallsyms_num_syms;
313 while (high - low > 1) {
314 mid = low + (high - low) / 2;
315 if (kallsyms_sym_address(mid) <= addr)
322 * Search for the first aliased symbol. Aliased
323 * symbols are symbols with the same address.
325 while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
328 symbol_start = kallsyms_sym_address(low);
330 /* Search for next non-aliased symbol. */
331 for (i = low + 1; i < kallsyms_num_syms; i++) {
332 if (kallsyms_sym_address(i) > symbol_start) {
333 symbol_end = kallsyms_sym_address(i);
338 /* If we found no next symbol, we use the end of the section. */
340 if (is_kernel_inittext(addr))
341 symbol_end = (unsigned long)_einittext;
342 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
343 symbol_end = (unsigned long)_end;
345 symbol_end = (unsigned long)_etext;
349 *symbolsize = symbol_end - symbol_start;
351 *offset = addr - symbol_start;
357 * Lookup an address but don't bother to find any names.
359 int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
360 unsigned long *offset)
362 char namebuf[KSYM_NAME_LEN];
364 if (is_ksym_addr(addr)) {
365 get_symbol_pos(addr, symbolsize, offset);
368 return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) ||
369 !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
372 static const char *kallsyms_lookup_buildid(unsigned long addr,
373 unsigned long *symbolsize,
374 unsigned long *offset, char **modname,
375 const unsigned char **modbuildid, char *namebuf)
379 namebuf[KSYM_NAME_LEN - 1] = 0;
382 if (is_ksym_addr(addr)) {
385 pos = get_symbol_pos(addr, symbolsize, offset);
387 kallsyms_expand_symbol(get_symbol_offset(pos),
388 namebuf, KSYM_NAME_LEN);
398 /* See if it's in a module or a BPF JITed image. */
399 ret = module_address_lookup(addr, symbolsize, offset,
400 modname, modbuildid, namebuf);
402 ret = bpf_address_lookup(addr, symbolsize,
403 offset, modname, namebuf);
406 ret = ftrace_mod_address_lookup(addr, symbolsize,
407 offset, modname, namebuf);
410 cleanup_symbol_name(namebuf);
416 * - modname is set to NULL if it's in the kernel.
417 * - We guarantee that the returned name is valid until we reschedule even if.
418 * It resides in a module.
419 * - We also guarantee that modname will be valid until rescheduled.
421 const char *kallsyms_lookup(unsigned long addr,
422 unsigned long *symbolsize,
423 unsigned long *offset,
424 char **modname, char *namebuf)
426 return kallsyms_lookup_buildid(addr, symbolsize, offset, modname,
430 int lookup_symbol_name(unsigned long addr, char *symname)
435 symname[KSYM_NAME_LEN - 1] = '\0';
437 if (is_ksym_addr(addr)) {
440 pos = get_symbol_pos(addr, NULL, NULL);
442 kallsyms_expand_symbol(get_symbol_offset(pos),
443 symname, KSYM_NAME_LEN);
446 /* See if it's in a module. */
447 res = lookup_module_symbol_name(addr, symname);
452 cleanup_symbol_name(symname);
456 int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
457 unsigned long *offset, char *modname, char *name)
462 name[KSYM_NAME_LEN - 1] = '\0';
464 if (is_ksym_addr(addr)) {
467 pos = get_symbol_pos(addr, size, offset);
469 kallsyms_expand_symbol(get_symbol_offset(pos),
470 name, KSYM_NAME_LEN);
474 /* See if it's in a module. */
475 res = lookup_module_symbol_attrs(addr, size, offset, modname, name);
480 cleanup_symbol_name(name);
484 /* Look up a kernel symbol and return it in a text buffer. */
485 static int __sprint_symbol(char *buffer, unsigned long address,
486 int symbol_offset, int add_offset, int add_buildid)
489 const unsigned char *buildid;
491 unsigned long offset, size;
494 address += symbol_offset;
495 name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid,
498 return sprintf(buffer, "0x%lx", address - symbol_offset);
501 strcpy(buffer, name);
502 len = strlen(buffer);
503 offset -= symbol_offset;
506 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
509 len += sprintf(buffer + len, " [%s", modname);
510 #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
511 if (add_buildid && buildid) {
512 /* build ID should match length of sprintf */
513 #if IS_ENABLED(CONFIG_MODULES)
514 static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
516 len += sprintf(buffer + len, " %20phN", buildid);
519 len += sprintf(buffer + len, "]");
526 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
527 * @buffer: buffer to be stored
528 * @address: address to lookup
530 * This function looks up a kernel symbol with @address and stores its name,
531 * offset, size and module name to @buffer if possible. If no symbol was found,
532 * just saves its @address as is.
534 * This function returns the number of bytes stored in @buffer.
536 int sprint_symbol(char *buffer, unsigned long address)
538 return __sprint_symbol(buffer, address, 0, 1, 0);
540 EXPORT_SYMBOL_GPL(sprint_symbol);
543 * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
544 * @buffer: buffer to be stored
545 * @address: address to lookup
547 * This function looks up a kernel symbol with @address and stores its name,
548 * offset, size, module name and module build ID to @buffer if possible. If no
549 * symbol was found, just saves its @address as is.
551 * This function returns the number of bytes stored in @buffer.
553 int sprint_symbol_build_id(char *buffer, unsigned long address)
555 return __sprint_symbol(buffer, address, 0, 1, 1);
557 EXPORT_SYMBOL_GPL(sprint_symbol_build_id);
560 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
561 * @buffer: buffer to be stored
562 * @address: address to lookup
564 * This function looks up a kernel symbol with @address and stores its name
565 * and module name to @buffer if possible. If no symbol was found, just saves
566 * its @address as is.
568 * This function returns the number of bytes stored in @buffer.
570 int sprint_symbol_no_offset(char *buffer, unsigned long address)
572 return __sprint_symbol(buffer, address, 0, 0, 0);
574 EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
577 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
578 * @buffer: buffer to be stored
579 * @address: address to lookup
581 * This function is for stack backtrace and does the same thing as
582 * sprint_symbol() but with modified/decreased @address. If there is a
583 * tail-call to the function marked "noreturn", gcc optimized out code after
584 * the call so that the stack-saved return address could point outside of the
585 * caller. This function ensures that kallsyms will find the original caller
586 * by decreasing @address.
588 * This function returns the number of bytes stored in @buffer.
590 int sprint_backtrace(char *buffer, unsigned long address)
592 return __sprint_symbol(buffer, address, -1, 1, 0);
596 * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
597 * @buffer: buffer to be stored
598 * @address: address to lookup
600 * This function is for stack backtrace and does the same thing as
601 * sprint_symbol() but with modified/decreased @address. If there is a
602 * tail-call to the function marked "noreturn", gcc optimized out code after
603 * the call so that the stack-saved return address could point outside of the
604 * caller. This function ensures that kallsyms will find the original caller
605 * by decreasing @address. This function also appends the module build ID to
606 * the @buffer if @address is within a kernel module.
608 * This function returns the number of bytes stored in @buffer.
610 int sprint_backtrace_build_id(char *buffer, unsigned long address)
612 return __sprint_symbol(buffer, address, -1, 1, 1);
615 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
616 struct kallsym_iter {
620 loff_t pos_ftrace_mod_end;
623 unsigned int nameoff; /* If iterating in core kernel symbols. */
625 char name[KSYM_NAME_LEN];
626 char module_name[MODULE_NAME_LEN];
631 int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
632 char *type, char *name)
637 static int get_ksymbol_arch(struct kallsym_iter *iter)
639 int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,
640 &iter->value, &iter->type,
644 iter->pos_arch_end = iter->pos;
651 static int get_ksymbol_mod(struct kallsym_iter *iter)
653 int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,
654 &iter->value, &iter->type,
655 iter->name, iter->module_name,
658 iter->pos_mod_end = iter->pos;
666 * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
667 * purposes. In that case "__builtin__ftrace" is used as a module name, even
668 * though "__builtin__ftrace" is not a module.
670 static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
672 int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
673 &iter->value, &iter->type,
674 iter->name, iter->module_name,
677 iter->pos_ftrace_mod_end = iter->pos;
684 static int get_ksymbol_bpf(struct kallsym_iter *iter)
688 strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
690 ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
691 &iter->value, &iter->type,
694 iter->pos_bpf_end = iter->pos;
702 * This uses "__builtin__kprobes" as a module name for symbols for pages
703 * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
706 static int get_ksymbol_kprobe(struct kallsym_iter *iter)
708 strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
710 return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
711 &iter->value, &iter->type,
712 iter->name) < 0 ? 0 : 1;
715 /* Returns space to next name. */
716 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
718 unsigned off = iter->nameoff;
720 iter->module_name[0] = '\0';
721 iter->value = kallsyms_sym_address(iter->pos);
723 iter->type = kallsyms_get_symbol_type(off);
725 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
727 return off - iter->nameoff;
730 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
732 iter->name[0] = '\0';
733 iter->nameoff = get_symbol_offset(new_pos);
736 iter->pos_arch_end = 0;
737 iter->pos_mod_end = 0;
738 iter->pos_ftrace_mod_end = 0;
739 iter->pos_bpf_end = 0;
744 * The end position (last + 1) of each additional kallsyms section is recorded
745 * in iter->pos_..._end as each section is added, and so can be used to
746 * determine which get_ksymbol_...() function to call next.
748 static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
752 if ((!iter->pos_arch_end || iter->pos_arch_end > pos) &&
753 get_ksymbol_arch(iter))
756 if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
757 get_ksymbol_mod(iter))
760 if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
761 get_ksymbol_ftrace_mod(iter))
764 if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
765 get_ksymbol_bpf(iter))
768 return get_ksymbol_kprobe(iter);
771 /* Returns false if pos at or past end of file. */
772 static int update_iter(struct kallsym_iter *iter, loff_t pos)
774 /* Module symbols can be accessed randomly. */
775 if (pos >= kallsyms_num_syms)
776 return update_iter_mod(iter, pos);
778 /* If we're not on the desired position, reset to new position. */
779 if (pos != iter->pos)
780 reset_iter(iter, pos);
782 iter->nameoff += get_ksymbol_core(iter);
788 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
792 if (!update_iter(m->private, *pos))
797 static void *s_start(struct seq_file *m, loff_t *pos)
799 if (!update_iter(m->private, *pos))
804 static void s_stop(struct seq_file *m, void *p)
808 static int s_show(struct seq_file *m, void *p)
811 struct kallsym_iter *iter = m->private;
813 /* Some debugging symbols have no name. Ignore them. */
817 value = iter->show_value ? (void *)iter->value : NULL;
819 if (iter->module_name[0]) {
823 * Label it "global" if it is exported,
824 * "local" if not exported.
826 type = iter->exported ? toupper(iter->type) :
828 seq_printf(m, "%px %c %s\t[%s]\n", value,
829 type, iter->name, iter->module_name);
831 seq_printf(m, "%px %c %s\n", value,
832 iter->type, iter->name);
836 static const struct seq_operations kallsyms_op = {
843 #ifdef CONFIG_BPF_SYSCALL
845 struct bpf_iter__ksym {
846 __bpf_md_ptr(struct bpf_iter_meta *, meta);
847 __bpf_md_ptr(struct kallsym_iter *, ksym);
850 static int ksym_prog_seq_show(struct seq_file *m, bool in_stop)
852 struct bpf_iter__ksym ctx;
853 struct bpf_iter_meta meta;
854 struct bpf_prog *prog;
857 prog = bpf_iter_get_info(&meta, in_stop);
862 ctx.ksym = m ? m->private : NULL;
863 return bpf_iter_run_prog(prog, &ctx);
866 static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p)
868 return ksym_prog_seq_show(m, false);
871 static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p)
874 (void) ksym_prog_seq_show(m, true);
879 static const struct seq_operations bpf_iter_ksym_ops = {
882 .stop = bpf_iter_ksym_seq_stop,
883 .show = bpf_iter_ksym_seq_show,
886 static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux)
888 struct kallsym_iter *iter = priv_data;
892 /* cache here as in kallsyms_open() case; use current process
893 * credentials to tell BPF iterators if values should be shown.
895 iter->show_value = kallsyms_show_value(current_cred());
900 DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym)
902 static const struct bpf_iter_seq_info ksym_iter_seq_info = {
903 .seq_ops = &bpf_iter_ksym_ops,
904 .init_seq_private = bpf_iter_ksym_init,
905 .fini_seq_private = NULL,
906 .seq_priv_size = sizeof(struct kallsym_iter),
909 static struct bpf_iter_reg ksym_iter_reg_info = {
911 .feature = BPF_ITER_RESCHED,
912 .ctx_arg_info_size = 1,
914 { offsetof(struct bpf_iter__ksym, ksym),
915 PTR_TO_BTF_ID_OR_NULL },
917 .seq_info = &ksym_iter_seq_info,
920 BTF_ID_LIST(btf_ksym_iter_id)
921 BTF_ID(struct, kallsym_iter)
923 static int __init bpf_ksym_iter_register(void)
925 ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id;
926 return bpf_iter_reg_target(&ksym_iter_reg_info);
929 late_initcall(bpf_ksym_iter_register);
931 #endif /* CONFIG_BPF_SYSCALL */
933 static inline int kallsyms_for_perf(void)
935 #ifdef CONFIG_PERF_EVENTS
936 extern int sysctl_perf_event_paranoid;
937 if (sysctl_perf_event_paranoid <= 1)
944 * We show kallsyms information even to normal users if we've enabled
945 * kernel profiling and are explicitly not paranoid (so kptr_restrict
946 * is clear, and sysctl_perf_event_paranoid isn't set).
948 * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
951 bool kallsyms_show_value(const struct cred *cred)
953 switch (kptr_restrict) {
955 if (kallsyms_for_perf())
959 if (security_capable(cred, &init_user_ns, CAP_SYSLOG,
960 CAP_OPT_NOAUDIT) == 0)
968 static int kallsyms_open(struct inode *inode, struct file *file)
971 * We keep iterator in m->private, since normal case is to
972 * s_start from where we left off, so we avoid doing
973 * using get_symbol_offset for every symbol.
975 struct kallsym_iter *iter;
976 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
982 * Instead of checking this on every s_show() call, cache
983 * the result here at open time.
985 iter->show_value = kallsyms_show_value(file->f_cred);
989 #ifdef CONFIG_KGDB_KDB
990 const char *kdb_walk_kallsyms(loff_t *pos)
992 static struct kallsym_iter kdb_walk_kallsyms_iter;
994 memset(&kdb_walk_kallsyms_iter, 0,
995 sizeof(kdb_walk_kallsyms_iter));
996 reset_iter(&kdb_walk_kallsyms_iter, 0);
999 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
1002 /* Some debugging symbols have no name. Ignore them. */
1003 if (kdb_walk_kallsyms_iter.name[0])
1004 return kdb_walk_kallsyms_iter.name;
1007 #endif /* CONFIG_KGDB_KDB */
1009 static const struct proc_ops kallsyms_proc_ops = {
1010 .proc_open = kallsyms_open,
1011 .proc_read = seq_read,
1012 .proc_lseek = seq_lseek,
1013 .proc_release = seq_release_private,
1016 static int __init kallsyms_init(void)
1018 proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
1021 device_initcall(kallsyms_init);