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 observed:
178 * - foo.llvm.[0-9a-f]+
181 res
= strchr(s
, '.');
190 /* Lookup the address for this symbol. Returns 0 if not found. */
191 unsigned long kallsyms_lookup_name(const char *name
)
193 char namebuf
[KSYM_NAME_LEN
];
197 /* Skip the search for empty string. */
201 for (i
= 0, off
= 0; i
< kallsyms_num_syms
; i
++) {
202 off
= kallsyms_expand_symbol(off
, namebuf
, ARRAY_SIZE(namebuf
));
204 if (strcmp(namebuf
, name
) == 0)
205 return kallsyms_sym_address(i
);
207 if (cleanup_symbol_name(namebuf
) && strcmp(namebuf
, name
) == 0)
208 return kallsyms_sym_address(i
);
210 return module_kallsyms_lookup_name(name
);
214 * Iterate over all symbols in vmlinux. For symbols from modules use
215 * module_kallsyms_on_each_symbol instead.
217 int kallsyms_on_each_symbol(int (*fn
)(void *, const char *, struct module
*,
221 char namebuf
[KSYM_NAME_LEN
];
226 for (i
= 0, off
= 0; i
< kallsyms_num_syms
; i
++) {
227 off
= kallsyms_expand_symbol(off
, namebuf
, ARRAY_SIZE(namebuf
));
228 ret
= fn(data
, namebuf
, NULL
, kallsyms_sym_address(i
));
236 static unsigned long get_symbol_pos(unsigned long addr
,
237 unsigned long *symbolsize
,
238 unsigned long *offset
)
240 unsigned long symbol_start
= 0, symbol_end
= 0;
241 unsigned long i
, low
, high
, mid
;
243 /* This kernel should never had been booted. */
244 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE
))
245 BUG_ON(!kallsyms_addresses
);
247 BUG_ON(!kallsyms_offsets
);
249 /* Do a binary search on the sorted kallsyms_addresses array. */
251 high
= kallsyms_num_syms
;
253 while (high
- low
> 1) {
254 mid
= low
+ (high
- low
) / 2;
255 if (kallsyms_sym_address(mid
) <= addr
)
262 * Search for the first aliased symbol. Aliased
263 * symbols are symbols with the same address.
265 while (low
&& kallsyms_sym_address(low
-1) == kallsyms_sym_address(low
))
268 symbol_start
= kallsyms_sym_address(low
);
270 /* Search for next non-aliased symbol. */
271 for (i
= low
+ 1; i
< kallsyms_num_syms
; i
++) {
272 if (kallsyms_sym_address(i
) > symbol_start
) {
273 symbol_end
= kallsyms_sym_address(i
);
278 /* If we found no next symbol, we use the end of the section. */
280 if (is_kernel_inittext(addr
))
281 symbol_end
= (unsigned long)_einittext
;
282 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL
))
283 symbol_end
= (unsigned long)_end
;
285 symbol_end
= (unsigned long)_etext
;
289 *symbolsize
= symbol_end
- symbol_start
;
291 *offset
= addr
- symbol_start
;
297 * Lookup an address but don't bother to find any names.
299 int kallsyms_lookup_size_offset(unsigned long addr
, unsigned long *symbolsize
,
300 unsigned long *offset
)
302 char namebuf
[KSYM_NAME_LEN
];
304 if (is_ksym_addr(addr
)) {
305 get_symbol_pos(addr
, symbolsize
, offset
);
308 return !!module_address_lookup(addr
, symbolsize
, offset
, NULL
, NULL
, namebuf
) ||
309 !!__bpf_address_lookup(addr
, symbolsize
, offset
, namebuf
);
312 static const char *kallsyms_lookup_buildid(unsigned long addr
,
313 unsigned long *symbolsize
,
314 unsigned long *offset
, char **modname
,
315 const unsigned char **modbuildid
, char *namebuf
)
319 namebuf
[KSYM_NAME_LEN
- 1] = 0;
322 if (is_ksym_addr(addr
)) {
325 pos
= get_symbol_pos(addr
, symbolsize
, offset
);
327 kallsyms_expand_symbol(get_symbol_offset(pos
),
328 namebuf
, KSYM_NAME_LEN
);
338 /* See if it's in a module or a BPF JITed image. */
339 ret
= module_address_lookup(addr
, symbolsize
, offset
,
340 modname
, modbuildid
, namebuf
);
342 ret
= bpf_address_lookup(addr
, symbolsize
,
343 offset
, modname
, namebuf
);
346 ret
= ftrace_mod_address_lookup(addr
, symbolsize
,
347 offset
, modname
, namebuf
);
350 cleanup_symbol_name(namebuf
);
356 * - modname is set to NULL if it's in the kernel.
357 * - We guarantee that the returned name is valid until we reschedule even if.
358 * It resides in a module.
359 * - We also guarantee that modname will be valid until rescheduled.
361 const char *kallsyms_lookup(unsigned long addr
,
362 unsigned long *symbolsize
,
363 unsigned long *offset
,
364 char **modname
, char *namebuf
)
366 return kallsyms_lookup_buildid(addr
, symbolsize
, offset
, modname
,
370 int lookup_symbol_name(unsigned long addr
, char *symname
)
375 symname
[KSYM_NAME_LEN
- 1] = '\0';
377 if (is_ksym_addr(addr
)) {
380 pos
= get_symbol_pos(addr
, NULL
, NULL
);
382 kallsyms_expand_symbol(get_symbol_offset(pos
),
383 symname
, KSYM_NAME_LEN
);
386 /* See if it's in a module. */
387 res
= lookup_module_symbol_name(addr
, symname
);
392 cleanup_symbol_name(symname
);
396 int lookup_symbol_attrs(unsigned long addr
, unsigned long *size
,
397 unsigned long *offset
, char *modname
, char *name
)
402 name
[KSYM_NAME_LEN
- 1] = '\0';
404 if (is_ksym_addr(addr
)) {
407 pos
= get_symbol_pos(addr
, size
, offset
);
409 kallsyms_expand_symbol(get_symbol_offset(pos
),
410 name
, KSYM_NAME_LEN
);
414 /* See if it's in a module. */
415 res
= lookup_module_symbol_attrs(addr
, size
, offset
, modname
, name
);
420 cleanup_symbol_name(name
);
424 /* Look up a kernel symbol and return it in a text buffer. */
425 static int __sprint_symbol(char *buffer
, unsigned long address
,
426 int symbol_offset
, int add_offset
, int add_buildid
)
429 const unsigned char *buildid
;
431 unsigned long offset
, size
;
434 address
+= symbol_offset
;
435 name
= kallsyms_lookup_buildid(address
, &size
, &offset
, &modname
, &buildid
,
438 return sprintf(buffer
, "0x%lx", address
- symbol_offset
);
441 strcpy(buffer
, name
);
442 len
= strlen(buffer
);
443 offset
-= symbol_offset
;
446 len
+= sprintf(buffer
+ len
, "+%#lx/%#lx", offset
, size
);
449 len
+= sprintf(buffer
+ len
, " [%s", modname
);
450 #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
451 if (add_buildid
&& buildid
) {
452 /* build ID should match length of sprintf */
453 #if IS_ENABLED(CONFIG_MODULES)
454 static_assert(sizeof(typeof_member(struct module
, build_id
)) == 20);
456 len
+= sprintf(buffer
+ len
, " %20phN", buildid
);
459 len
+= sprintf(buffer
+ len
, "]");
466 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
467 * @buffer: buffer to be stored
468 * @address: address to lookup
470 * This function looks up a kernel symbol with @address and stores its name,
471 * offset, size and module name to @buffer if possible. If no symbol was found,
472 * just saves its @address as is.
474 * This function returns the number of bytes stored in @buffer.
476 int sprint_symbol(char *buffer
, unsigned long address
)
478 return __sprint_symbol(buffer
, address
, 0, 1, 0);
480 EXPORT_SYMBOL_GPL(sprint_symbol
);
483 * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
484 * @buffer: buffer to be stored
485 * @address: address to lookup
487 * This function looks up a kernel symbol with @address and stores its name,
488 * offset, size, module name and module build ID to @buffer if possible. If no
489 * symbol was found, just saves its @address as is.
491 * This function returns the number of bytes stored in @buffer.
493 int sprint_symbol_build_id(char *buffer
, unsigned long address
)
495 return __sprint_symbol(buffer
, address
, 0, 1, 1);
497 EXPORT_SYMBOL_GPL(sprint_symbol_build_id
);
500 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
501 * @buffer: buffer to be stored
502 * @address: address to lookup
504 * This function looks up a kernel symbol with @address and stores its name
505 * and module name to @buffer if possible. If no symbol was found, just saves
506 * its @address as is.
508 * This function returns the number of bytes stored in @buffer.
510 int sprint_symbol_no_offset(char *buffer
, unsigned long address
)
512 return __sprint_symbol(buffer
, address
, 0, 0, 0);
514 EXPORT_SYMBOL_GPL(sprint_symbol_no_offset
);
517 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
518 * @buffer: buffer to be stored
519 * @address: address to lookup
521 * This function is for stack backtrace and does the same thing as
522 * sprint_symbol() but with modified/decreased @address. If there is a
523 * tail-call to the function marked "noreturn", gcc optimized out code after
524 * the call so that the stack-saved return address could point outside of the
525 * caller. This function ensures that kallsyms will find the original caller
526 * by decreasing @address.
528 * This function returns the number of bytes stored in @buffer.
530 int sprint_backtrace(char *buffer
, unsigned long address
)
532 return __sprint_symbol(buffer
, address
, -1, 1, 0);
536 * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
537 * @buffer: buffer to be stored
538 * @address: address to lookup
540 * This function is for stack backtrace and does the same thing as
541 * sprint_symbol() but with modified/decreased @address. If there is a
542 * tail-call to the function marked "noreturn", gcc optimized out code after
543 * the call so that the stack-saved return address could point outside of the
544 * caller. This function ensures that kallsyms will find the original caller
545 * by decreasing @address. This function also appends the module build ID to
546 * the @buffer if @address is within a kernel module.
548 * This function returns the number of bytes stored in @buffer.
550 int sprint_backtrace_build_id(char *buffer
, unsigned long address
)
552 return __sprint_symbol(buffer
, address
, -1, 1, 1);
555 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
556 struct kallsym_iter
{
560 loff_t pos_ftrace_mod_end
;
563 unsigned int nameoff
; /* If iterating in core kernel symbols. */
565 char name
[KSYM_NAME_LEN
];
566 char module_name
[MODULE_NAME_LEN
];
571 int __weak
arch_get_kallsym(unsigned int symnum
, unsigned long *value
,
572 char *type
, char *name
)
577 static int get_ksymbol_arch(struct kallsym_iter
*iter
)
579 int ret
= arch_get_kallsym(iter
->pos
- kallsyms_num_syms
,
580 &iter
->value
, &iter
->type
,
584 iter
->pos_arch_end
= iter
->pos
;
591 static int get_ksymbol_mod(struct kallsym_iter
*iter
)
593 int ret
= module_get_kallsym(iter
->pos
- iter
->pos_arch_end
,
594 &iter
->value
, &iter
->type
,
595 iter
->name
, iter
->module_name
,
598 iter
->pos_mod_end
= iter
->pos
;
606 * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
607 * purposes. In that case "__builtin__ftrace" is used as a module name, even
608 * though "__builtin__ftrace" is not a module.
610 static int get_ksymbol_ftrace_mod(struct kallsym_iter
*iter
)
612 int ret
= ftrace_mod_get_kallsym(iter
->pos
- iter
->pos_mod_end
,
613 &iter
->value
, &iter
->type
,
614 iter
->name
, iter
->module_name
,
617 iter
->pos_ftrace_mod_end
= iter
->pos
;
624 static int get_ksymbol_bpf(struct kallsym_iter
*iter
)
628 strlcpy(iter
->module_name
, "bpf", MODULE_NAME_LEN
);
630 ret
= bpf_get_kallsym(iter
->pos
- iter
->pos_ftrace_mod_end
,
631 &iter
->value
, &iter
->type
,
634 iter
->pos_bpf_end
= iter
->pos
;
642 * This uses "__builtin__kprobes" as a module name for symbols for pages
643 * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
646 static int get_ksymbol_kprobe(struct kallsym_iter
*iter
)
648 strlcpy(iter
->module_name
, "__builtin__kprobes", MODULE_NAME_LEN
);
650 return kprobe_get_kallsym(iter
->pos
- iter
->pos_bpf_end
,
651 &iter
->value
, &iter
->type
,
652 iter
->name
) < 0 ? 0 : 1;
655 /* Returns space to next name. */
656 static unsigned long get_ksymbol_core(struct kallsym_iter
*iter
)
658 unsigned off
= iter
->nameoff
;
660 iter
->module_name
[0] = '\0';
661 iter
->value
= kallsyms_sym_address(iter
->pos
);
663 iter
->type
= kallsyms_get_symbol_type(off
);
665 off
= kallsyms_expand_symbol(off
, iter
->name
, ARRAY_SIZE(iter
->name
));
667 return off
- iter
->nameoff
;
670 static void reset_iter(struct kallsym_iter
*iter
, loff_t new_pos
)
672 iter
->name
[0] = '\0';
673 iter
->nameoff
= get_symbol_offset(new_pos
);
676 iter
->pos_arch_end
= 0;
677 iter
->pos_mod_end
= 0;
678 iter
->pos_ftrace_mod_end
= 0;
679 iter
->pos_bpf_end
= 0;
684 * The end position (last + 1) of each additional kallsyms section is recorded
685 * in iter->pos_..._end as each section is added, and so can be used to
686 * determine which get_ksymbol_...() function to call next.
688 static int update_iter_mod(struct kallsym_iter
*iter
, loff_t pos
)
692 if ((!iter
->pos_arch_end
|| iter
->pos_arch_end
> pos
) &&
693 get_ksymbol_arch(iter
))
696 if ((!iter
->pos_mod_end
|| iter
->pos_mod_end
> pos
) &&
697 get_ksymbol_mod(iter
))
700 if ((!iter
->pos_ftrace_mod_end
|| iter
->pos_ftrace_mod_end
> pos
) &&
701 get_ksymbol_ftrace_mod(iter
))
704 if ((!iter
->pos_bpf_end
|| iter
->pos_bpf_end
> pos
) &&
705 get_ksymbol_bpf(iter
))
708 return get_ksymbol_kprobe(iter
);
711 /* Returns false if pos at or past end of file. */
712 static int update_iter(struct kallsym_iter
*iter
, loff_t pos
)
714 /* Module symbols can be accessed randomly. */
715 if (pos
>= kallsyms_num_syms
)
716 return update_iter_mod(iter
, pos
);
718 /* If we're not on the desired position, reset to new position. */
719 if (pos
!= iter
->pos
)
720 reset_iter(iter
, pos
);
722 iter
->nameoff
+= get_ksymbol_core(iter
);
728 static void *s_next(struct seq_file
*m
, void *p
, loff_t
*pos
)
732 if (!update_iter(m
->private, *pos
))
737 static void *s_start(struct seq_file
*m
, loff_t
*pos
)
739 if (!update_iter(m
->private, *pos
))
744 static void s_stop(struct seq_file
*m
, void *p
)
748 static int s_show(struct seq_file
*m
, void *p
)
751 struct kallsym_iter
*iter
= m
->private;
753 /* Some debugging symbols have no name. Ignore them. */
757 value
= iter
->show_value
? (void *)iter
->value
: NULL
;
759 if (iter
->module_name
[0]) {
763 * Label it "global" if it is exported,
764 * "local" if not exported.
766 type
= iter
->exported
? toupper(iter
->type
) :
768 seq_printf(m
, "%px %c %s\t[%s]\n", value
,
769 type
, iter
->name
, iter
->module_name
);
771 seq_printf(m
, "%px %c %s\n", value
,
772 iter
->type
, iter
->name
);
776 static const struct seq_operations kallsyms_op
= {
783 #ifdef CONFIG_BPF_SYSCALL
785 struct bpf_iter__ksym
{
786 __bpf_md_ptr(struct bpf_iter_meta
*, meta
);
787 __bpf_md_ptr(struct kallsym_iter
*, ksym
);
790 static int ksym_prog_seq_show(struct seq_file
*m
, bool in_stop
)
792 struct bpf_iter__ksym ctx
;
793 struct bpf_iter_meta meta
;
794 struct bpf_prog
*prog
;
797 prog
= bpf_iter_get_info(&meta
, in_stop
);
802 ctx
.ksym
= m
? m
->private : NULL
;
803 return bpf_iter_run_prog(prog
, &ctx
);
806 static int bpf_iter_ksym_seq_show(struct seq_file
*m
, void *p
)
808 return ksym_prog_seq_show(m
, false);
811 static void bpf_iter_ksym_seq_stop(struct seq_file
*m
, void *p
)
814 (void) ksym_prog_seq_show(m
, true);
819 static const struct seq_operations bpf_iter_ksym_ops
= {
822 .stop
= bpf_iter_ksym_seq_stop
,
823 .show
= bpf_iter_ksym_seq_show
,
826 static int bpf_iter_ksym_init(void *priv_data
, struct bpf_iter_aux_info
*aux
)
828 struct kallsym_iter
*iter
= priv_data
;
832 /* cache here as in kallsyms_open() case; use current process
833 * credentials to tell BPF iterators if values should be shown.
835 iter
->show_value
= kallsyms_show_value(current_cred());
840 DEFINE_BPF_ITER_FUNC(ksym
, struct bpf_iter_meta
*meta
, struct kallsym_iter
*ksym
)
842 static const struct bpf_iter_seq_info ksym_iter_seq_info
= {
843 .seq_ops
= &bpf_iter_ksym_ops
,
844 .init_seq_private
= bpf_iter_ksym_init
,
845 .fini_seq_private
= NULL
,
846 .seq_priv_size
= sizeof(struct kallsym_iter
),
849 static struct bpf_iter_reg ksym_iter_reg_info
= {
851 .feature
= BPF_ITER_RESCHED
,
852 .ctx_arg_info_size
= 1,
854 { offsetof(struct bpf_iter__ksym
, ksym
),
855 PTR_TO_BTF_ID_OR_NULL
},
857 .seq_info
= &ksym_iter_seq_info
,
860 BTF_ID_LIST(btf_ksym_iter_id
)
861 BTF_ID(struct, kallsym_iter
)
863 static int __init
bpf_ksym_iter_register(void)
865 ksym_iter_reg_info
.ctx_arg_info
[0].btf_id
= *btf_ksym_iter_id
;
866 return bpf_iter_reg_target(&ksym_iter_reg_info
);
869 late_initcall(bpf_ksym_iter_register
);
871 #endif /* CONFIG_BPF_SYSCALL */
873 static inline int kallsyms_for_perf(void)
875 #ifdef CONFIG_PERF_EVENTS
876 extern int sysctl_perf_event_paranoid
;
877 if (sysctl_perf_event_paranoid
<= 1)
884 * We show kallsyms information even to normal users if we've enabled
885 * kernel profiling and are explicitly not paranoid (so kptr_restrict
886 * is clear, and sysctl_perf_event_paranoid isn't set).
888 * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
891 bool kallsyms_show_value(const struct cred
*cred
)
893 switch (kptr_restrict
) {
895 if (kallsyms_for_perf())
899 if (security_capable(cred
, &init_user_ns
, CAP_SYSLOG
,
900 CAP_OPT_NOAUDIT
) == 0)
908 static int kallsyms_open(struct inode
*inode
, struct file
*file
)
911 * We keep iterator in m->private, since normal case is to
912 * s_start from where we left off, so we avoid doing
913 * using get_symbol_offset for every symbol.
915 struct kallsym_iter
*iter
;
916 iter
= __seq_open_private(file
, &kallsyms_op
, sizeof(*iter
));
922 * Instead of checking this on every s_show() call, cache
923 * the result here at open time.
925 iter
->show_value
= kallsyms_show_value(file
->f_cred
);
929 #ifdef CONFIG_KGDB_KDB
930 const char *kdb_walk_kallsyms(loff_t
*pos
)
932 static struct kallsym_iter kdb_walk_kallsyms_iter
;
934 memset(&kdb_walk_kallsyms_iter
, 0,
935 sizeof(kdb_walk_kallsyms_iter
));
936 reset_iter(&kdb_walk_kallsyms_iter
, 0);
939 if (!update_iter(&kdb_walk_kallsyms_iter
, *pos
))
942 /* Some debugging symbols have no name. Ignore them. */
943 if (kdb_walk_kallsyms_iter
.name
[0])
944 return kdb_walk_kallsyms_iter
.name
;
947 #endif /* CONFIG_KGDB_KDB */
949 static const struct proc_ops kallsyms_proc_ops
= {
950 .proc_open
= kallsyms_open
,
951 .proc_read
= seq_read
,
952 .proc_lseek
= seq_lseek
,
953 .proc_release
= seq_release_private
,
956 static int __init
kallsyms_init(void)
958 proc_create("kallsyms", 0444, NULL
, &kallsyms_proc_ops
);
961 device_initcall(kallsyms_init
);