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 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 void 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.");
187 static int compare_symbol_name(const char *name
, char *namebuf
)
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.
194 cleanup_symbol_name(namebuf
);
195 return strcmp(name
, namebuf
);
198 static unsigned int get_symbol_seq(int index
)
200 unsigned int i
, seq
= 0;
202 for (i
= 0; i
< 3; i
++)
203 seq
= (seq
<< 8) | kallsyms_seqs_of_names
[3 * index
+ i
];
208 static int kallsyms_lookup_names(const char *name
,
214 unsigned int seq
, off
;
215 char namebuf
[KSYM_NAME_LEN
];
218 high
= kallsyms_num_syms
- 1;
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
);
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
))
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
))
264 /* Lookup the address for this symbol. Returns 0 if not found. */
265 unsigned long kallsyms_lookup_name(const char *name
)
270 /* Skip the search for empty string. */
274 ret
= kallsyms_lookup_names(name
, &i
, NULL
);
276 return kallsyms_sym_address(get_symbol_seq(i
));
278 return module_kallsyms_lookup_name(name
);
282 * Iterate over all symbols in vmlinux. For symbols from modules use
283 * module_kallsyms_on_each_symbol instead.
285 int kallsyms_on_each_symbol(int (*fn
)(void *, const char *, unsigned long),
288 char namebuf
[KSYM_NAME_LEN
];
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
));
303 int kallsyms_on_each_match_symbol(int (*fn
)(void *, unsigned long),
304 const char *name
, void *data
)
307 unsigned int i
, start
, end
;
309 ret
= kallsyms_lookup_names(name
, &start
, &end
);
313 for (i
= start
; !ret
&& i
<= end
; i
++) {
314 ret
= fn(data
, kallsyms_sym_address(get_symbol_seq(i
)));
321 static unsigned long get_symbol_pos(unsigned long addr
,
322 unsigned long *symbolsize
,
323 unsigned long *offset
)
325 unsigned long symbol_start
= 0, symbol_end
= 0;
326 unsigned long i
, low
, high
, mid
;
328 /* This kernel should never had been booted. */
329 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE
))
330 BUG_ON(!kallsyms_addresses
);
332 BUG_ON(!kallsyms_offsets
);
334 /* Do a binary search on the sorted kallsyms_addresses array. */
336 high
= kallsyms_num_syms
;
338 while (high
- low
> 1) {
339 mid
= low
+ (high
- low
) / 2;
340 if (kallsyms_sym_address(mid
) <= addr
)
347 * Search for the first aliased symbol. Aliased
348 * symbols are symbols with the same address.
350 while (low
&& kallsyms_sym_address(low
-1) == kallsyms_sym_address(low
))
353 symbol_start
= kallsyms_sym_address(low
);
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
);
363 /* If we found no next symbol, we use the end of the section. */
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
;
370 symbol_end
= (unsigned long)_etext
;
374 *symbolsize
= symbol_end
- symbol_start
;
376 *offset
= addr
- symbol_start
;
382 * Lookup an address but don't bother to find any names.
384 int kallsyms_lookup_size_offset(unsigned long addr
, unsigned long *symbolsize
,
385 unsigned long *offset
)
387 char namebuf
[KSYM_NAME_LEN
];
389 if (is_ksym_addr(addr
)) {
390 get_symbol_pos(addr
, symbolsize
, offset
);
393 return !!module_address_lookup(addr
, symbolsize
, offset
, NULL
, NULL
, namebuf
) ||
394 !!__bpf_address_lookup(addr
, symbolsize
, offset
, namebuf
);
397 static 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
)
404 namebuf
[KSYM_NAME_LEN
- 1] = 0;
407 if (is_ksym_addr(addr
)) {
410 pos
= get_symbol_pos(addr
, symbolsize
, offset
);
412 kallsyms_expand_symbol(get_symbol_offset(pos
),
413 namebuf
, KSYM_NAME_LEN
);
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
);
427 ret
= bpf_address_lookup(addr
, symbolsize
,
428 offset
, modname
, namebuf
);
431 ret
= ftrace_mod_address_lookup(addr
, symbolsize
,
432 offset
, modname
, namebuf
);
435 cleanup_symbol_name(namebuf
);
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.
446 const char *kallsyms_lookup(unsigned long addr
,
447 unsigned long *symbolsize
,
448 unsigned long *offset
,
449 char **modname
, char *namebuf
)
451 return kallsyms_lookup_buildid(addr
, symbolsize
, offset
, modname
,
455 int lookup_symbol_name(unsigned long addr
, char *symname
)
460 symname
[KSYM_NAME_LEN
- 1] = '\0';
462 if (is_ksym_addr(addr
)) {
465 pos
= get_symbol_pos(addr
, NULL
, NULL
);
467 kallsyms_expand_symbol(get_symbol_offset(pos
),
468 symname
, KSYM_NAME_LEN
);
471 /* See if it's in a module. */
472 res
= lookup_module_symbol_name(addr
, symname
);
477 cleanup_symbol_name(symname
);
481 /* Look up a kernel symbol and return it in a text buffer. */
482 static int __sprint_symbol(char *buffer
, unsigned long address
,
483 int symbol_offset
, int add_offset
, int add_buildid
)
486 const unsigned char *buildid
;
488 unsigned long offset
, size
;
491 address
+= symbol_offset
;
492 name
= kallsyms_lookup_buildid(address
, &size
, &offset
, &modname
, &buildid
,
495 return sprintf(buffer
, "0x%lx", address
- symbol_offset
);
498 strcpy(buffer
, name
);
499 len
= strlen(buffer
);
500 offset
-= symbol_offset
;
503 len
+= sprintf(buffer
+ len
, "+%#lx/%#lx", offset
, size
);
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);
513 len
+= sprintf(buffer
+ len
, " %20phN", buildid
);
516 len
+= sprintf(buffer
+ len
, "]");
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
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.
531 * This function returns the number of bytes stored in @buffer.
533 int sprint_symbol(char *buffer
, unsigned long address
)
535 return __sprint_symbol(buffer
, address
, 0, 1, 0);
537 EXPORT_SYMBOL_GPL(sprint_symbol
);
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
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.
548 * This function returns the number of bytes stored in @buffer.
550 int sprint_symbol_build_id(char *buffer
, unsigned long address
)
552 return __sprint_symbol(buffer
, address
, 0, 1, 1);
554 EXPORT_SYMBOL_GPL(sprint_symbol_build_id
);
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
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.
565 * This function returns the number of bytes stored in @buffer.
567 int sprint_symbol_no_offset(char *buffer
, unsigned long address
)
569 return __sprint_symbol(buffer
, address
, 0, 0, 0);
571 EXPORT_SYMBOL_GPL(sprint_symbol_no_offset
);
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
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.
585 * This function returns the number of bytes stored in @buffer.
587 int sprint_backtrace(char *buffer
, unsigned long address
)
589 return __sprint_symbol(buffer
, address
, -1, 1, 0);
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
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.
605 * This function returns the number of bytes stored in @buffer.
607 int sprint_backtrace_build_id(char *buffer
, unsigned long address
)
609 return __sprint_symbol(buffer
, address
, -1, 1, 1);
612 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
613 struct kallsym_iter
{
616 loff_t pos_ftrace_mod_end
;
619 unsigned int nameoff
; /* If iterating in core kernel symbols. */
621 char name
[KSYM_NAME_LEN
];
622 char module_name
[MODULE_NAME_LEN
];
627 static int get_ksymbol_mod(struct kallsym_iter
*iter
)
629 int ret
= module_get_kallsym(iter
->pos
- kallsyms_num_syms
,
630 &iter
->value
, &iter
->type
,
631 iter
->name
, iter
->module_name
,
634 iter
->pos_mod_end
= iter
->pos
;
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.
646 static int get_ksymbol_ftrace_mod(struct kallsym_iter
*iter
)
648 int ret
= ftrace_mod_get_kallsym(iter
->pos
- iter
->pos_mod_end
,
649 &iter
->value
, &iter
->type
,
650 iter
->name
, iter
->module_name
,
653 iter
->pos_ftrace_mod_end
= iter
->pos
;
660 static int get_ksymbol_bpf(struct kallsym_iter
*iter
)
664 strscpy(iter
->module_name
, "bpf", MODULE_NAME_LEN
);
666 ret
= bpf_get_kallsym(iter
->pos
- iter
->pos_ftrace_mod_end
,
667 &iter
->value
, &iter
->type
,
670 iter
->pos_bpf_end
= iter
->pos
;
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
682 static int get_ksymbol_kprobe(struct kallsym_iter
*iter
)
684 strscpy(iter
->module_name
, "__builtin__kprobes", MODULE_NAME_LEN
);
686 return kprobe_get_kallsym(iter
->pos
- iter
->pos_bpf_end
,
687 &iter
->value
, &iter
->type
,
688 iter
->name
) < 0 ? 0 : 1;
691 /* Returns space to next name. */
692 static unsigned long get_ksymbol_core(struct kallsym_iter
*iter
)
694 unsigned off
= iter
->nameoff
;
696 iter
->module_name
[0] = '\0';
697 iter
->value
= kallsyms_sym_address(iter
->pos
);
699 iter
->type
= kallsyms_get_symbol_type(off
);
701 off
= kallsyms_expand_symbol(off
, iter
->name
, ARRAY_SIZE(iter
->name
));
703 return off
- iter
->nameoff
;
706 static void reset_iter(struct kallsym_iter
*iter
, loff_t new_pos
)
708 iter
->name
[0] = '\0';
709 iter
->nameoff
= get_symbol_offset(new_pos
);
712 iter
->pos_mod_end
= 0;
713 iter
->pos_ftrace_mod_end
= 0;
714 iter
->pos_bpf_end
= 0;
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.
723 static int update_iter_mod(struct kallsym_iter
*iter
, loff_t pos
)
727 if ((!iter
->pos_mod_end
|| iter
->pos_mod_end
> pos
) &&
728 get_ksymbol_mod(iter
))
731 if ((!iter
->pos_ftrace_mod_end
|| iter
->pos_ftrace_mod_end
> pos
) &&
732 get_ksymbol_ftrace_mod(iter
))
735 if ((!iter
->pos_bpf_end
|| iter
->pos_bpf_end
> pos
) &&
736 get_ksymbol_bpf(iter
))
739 return get_ksymbol_kprobe(iter
);
742 /* Returns false if pos at or past end of file. */
743 static int update_iter(struct kallsym_iter
*iter
, loff_t pos
)
745 /* Module symbols can be accessed randomly. */
746 if (pos
>= kallsyms_num_syms
)
747 return update_iter_mod(iter
, pos
);
749 /* If we're not on the desired position, reset to new position. */
750 if (pos
!= iter
->pos
)
751 reset_iter(iter
, pos
);
753 iter
->nameoff
+= get_ksymbol_core(iter
);
759 static void *s_next(struct seq_file
*m
, void *p
, loff_t
*pos
)
763 if (!update_iter(m
->private, *pos
))
768 static void *s_start(struct seq_file
*m
, loff_t
*pos
)
770 if (!update_iter(m
->private, *pos
))
775 static void s_stop(struct seq_file
*m
, void *p
)
779 static int s_show(struct seq_file
*m
, void *p
)
782 struct kallsym_iter
*iter
= m
->private;
784 /* Some debugging symbols have no name. Ignore them. */
788 value
= iter
->show_value
? (void *)iter
->value
: NULL
;
790 if (iter
->module_name
[0]) {
794 * Label it "global" if it is exported,
795 * "local" if not exported.
797 type
= iter
->exported
? toupper(iter
->type
) :
799 seq_printf(m
, "%px %c %s\t[%s]\n", value
,
800 type
, iter
->name
, iter
->module_name
);
802 seq_printf(m
, "%px %c %s\n", value
,
803 iter
->type
, iter
->name
);
807 static const struct seq_operations kallsyms_op
= {
814 #ifdef CONFIG_BPF_SYSCALL
816 struct bpf_iter__ksym
{
817 __bpf_md_ptr(struct bpf_iter_meta
*, meta
);
818 __bpf_md_ptr(struct kallsym_iter
*, ksym
);
821 static int ksym_prog_seq_show(struct seq_file
*m
, bool in_stop
)
823 struct bpf_iter__ksym ctx
;
824 struct bpf_iter_meta meta
;
825 struct bpf_prog
*prog
;
828 prog
= bpf_iter_get_info(&meta
, in_stop
);
833 ctx
.ksym
= m
? m
->private : NULL
;
834 return bpf_iter_run_prog(prog
, &ctx
);
837 static int bpf_iter_ksym_seq_show(struct seq_file
*m
, void *p
)
839 return ksym_prog_seq_show(m
, false);
842 static void bpf_iter_ksym_seq_stop(struct seq_file
*m
, void *p
)
845 (void) ksym_prog_seq_show(m
, true);
850 static const struct seq_operations bpf_iter_ksym_ops
= {
853 .stop
= bpf_iter_ksym_seq_stop
,
854 .show
= bpf_iter_ksym_seq_show
,
857 static int bpf_iter_ksym_init(void *priv_data
, struct bpf_iter_aux_info
*aux
)
859 struct kallsym_iter
*iter
= priv_data
;
863 /* cache here as in kallsyms_open() case; use current process
864 * credentials to tell BPF iterators if values should be shown.
866 iter
->show_value
= kallsyms_show_value(current_cred());
871 DEFINE_BPF_ITER_FUNC(ksym
, struct bpf_iter_meta
*meta
, struct kallsym_iter
*ksym
)
873 static 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
),
880 static struct bpf_iter_reg ksym_iter_reg_info
= {
882 .feature
= BPF_ITER_RESCHED
,
883 .ctx_arg_info_size
= 1,
885 { offsetof(struct bpf_iter__ksym
, ksym
),
886 PTR_TO_BTF_ID_OR_NULL
},
888 .seq_info
= &ksym_iter_seq_info
,
891 BTF_ID_LIST(btf_ksym_iter_id
)
892 BTF_ID(struct, kallsym_iter
)
894 static int __init
bpf_ksym_iter_register(void)
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
);
900 late_initcall(bpf_ksym_iter_register
);
902 #endif /* CONFIG_BPF_SYSCALL */
904 static int kallsyms_open(struct inode
*inode
, struct file
*file
)
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.
911 struct kallsym_iter
*iter
;
912 iter
= __seq_open_private(file
, &kallsyms_op
, sizeof(*iter
));
918 * Instead of checking this on every s_show() call, cache
919 * the result here at open time.
921 iter
->show_value
= kallsyms_show_value(file
->f_cred
);
925 #ifdef CONFIG_KGDB_KDB
926 const char *kdb_walk_kallsyms(loff_t
*pos
)
928 static struct kallsym_iter kdb_walk_kallsyms_iter
;
930 memset(&kdb_walk_kallsyms_iter
, 0,
931 sizeof(kdb_walk_kallsyms_iter
));
932 reset_iter(&kdb_walk_kallsyms_iter
, 0);
935 if (!update_iter(&kdb_walk_kallsyms_iter
, *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
;
943 #endif /* CONFIG_KGDB_KDB */
945 static 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
,
952 static int __init
kallsyms_init(void)
954 proc_create("kallsyms", 0444, NULL
, &kallsyms_proc_ops
);
957 device_initcall(kallsyms_init
);