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 * Update the offset to return the offset for the next symbol on
56 * the compressed stream.
61 * For every byte on the compressed symbol data, copy the table
62 * entry for that byte.
65 tptr
= &kallsyms_token_table
[kallsyms_token_index
[*data
]];
86 /* Return to offset to the next symbol. */
91 * Get symbol type information. This is encoded as a single char at the
92 * beginning of the symbol name.
94 static char kallsyms_get_symbol_type(unsigned int off
)
97 * Get just the first code, look it up in the token table,
98 * and return the first char from this token.
100 return kallsyms_token_table
[kallsyms_token_index
[kallsyms_names
[off
+ 1]]];
105 * Find the offset on the compressed stream given and index in the
108 static unsigned int get_symbol_offset(unsigned long pos
)
114 * Use the closest marker we have. We have markers every 256 positions,
115 * so that should be close enough.
117 name
= &kallsyms_names
[kallsyms_markers
[pos
>> 8]];
120 * Sequentially scan all the symbols up to the point we're searching
121 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
122 * so we just need to add the len to the current pointer for every
123 * symbol we wish to skip.
125 for (i
= 0; i
< (pos
& 0xFF); i
++)
126 name
= name
+ (*name
) + 1;
128 return name
- kallsyms_names
;
131 static unsigned long kallsyms_sym_address(int idx
)
133 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE
))
134 return kallsyms_addresses
[idx
];
136 /* values are unsigned offsets if --absolute-percpu is not in effect */
137 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU
))
138 return kallsyms_relative_base
+ (u32
)kallsyms_offsets
[idx
];
140 /* ...otherwise, positive offsets are absolute values */
141 if (kallsyms_offsets
[idx
] >= 0)
142 return kallsyms_offsets
[idx
];
144 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
145 return kallsyms_relative_base
- 1 - kallsyms_offsets
[idx
];
148 static bool cleanup_symbol_name(char *s
)
152 if (!IS_ENABLED(CONFIG_LTO_CLANG
))
156 * LLVM appends various suffixes for local functions and variables that
157 * must be promoted to global scope as part of LTO. This can break
158 * hooking of static functions with kprobes. '.' is not a valid
159 * character in an identifier in C. Suffixes observed:
160 * - foo.llvm.[0-9a-f]+
162 * - foo.[0-9a-f]+.cfi_jt
164 res
= strchr(s
, '.');
170 if (!IS_ENABLED(CONFIG_CFI_CLANG
) ||
171 !IS_ENABLED(CONFIG_LTO_CLANG_THIN
) ||
172 CONFIG_CLANG_VERSION
>= 130000)
176 * Prior to LLVM 13, the following suffixes were observed when thinLTO
177 * and CFI are both enabled:
180 res
= strrchr(s
, '$');
189 /* Lookup the address for this symbol. Returns 0 if not found. */
190 unsigned long kallsyms_lookup_name(const char *name
)
192 char namebuf
[KSYM_NAME_LEN
];
196 /* Skip the search for empty string. */
200 for (i
= 0, off
= 0; i
< kallsyms_num_syms
; i
++) {
201 off
= kallsyms_expand_symbol(off
, namebuf
, ARRAY_SIZE(namebuf
));
203 if (strcmp(namebuf
, name
) == 0)
204 return kallsyms_sym_address(i
);
206 if (cleanup_symbol_name(namebuf
) && strcmp(namebuf
, name
) == 0)
207 return kallsyms_sym_address(i
);
209 return module_kallsyms_lookup_name(name
);
213 * Iterate over all symbols in vmlinux. For symbols from modules use
214 * module_kallsyms_on_each_symbol instead.
216 int kallsyms_on_each_symbol(int (*fn
)(void *, const char *, struct module
*,
220 char namebuf
[KSYM_NAME_LEN
];
225 for (i
= 0, off
= 0; i
< kallsyms_num_syms
; i
++) {
226 off
= kallsyms_expand_symbol(off
, namebuf
, ARRAY_SIZE(namebuf
));
227 ret
= fn(data
, namebuf
, NULL
, kallsyms_sym_address(i
));
235 static unsigned long get_symbol_pos(unsigned long addr
,
236 unsigned long *symbolsize
,
237 unsigned long *offset
)
239 unsigned long symbol_start
= 0, symbol_end
= 0;
240 unsigned long i
, low
, high
, mid
;
242 /* This kernel should never had been booted. */
243 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE
))
244 BUG_ON(!kallsyms_addresses
);
246 BUG_ON(!kallsyms_offsets
);
248 /* Do a binary search on the sorted kallsyms_addresses array. */
250 high
= kallsyms_num_syms
;
252 while (high
- low
> 1) {
253 mid
= low
+ (high
- low
) / 2;
254 if (kallsyms_sym_address(mid
) <= addr
)
261 * Search for the first aliased symbol. Aliased
262 * symbols are symbols with the same address.
264 while (low
&& kallsyms_sym_address(low
-1) == kallsyms_sym_address(low
))
267 symbol_start
= kallsyms_sym_address(low
);
269 /* Search for next non-aliased symbol. */
270 for (i
= low
+ 1; i
< kallsyms_num_syms
; i
++) {
271 if (kallsyms_sym_address(i
) > symbol_start
) {
272 symbol_end
= kallsyms_sym_address(i
);
277 /* If we found no next symbol, we use the end of the section. */
279 if (is_kernel_inittext(addr
))
280 symbol_end
= (unsigned long)_einittext
;
281 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL
))
282 symbol_end
= (unsigned long)_end
;
284 symbol_end
= (unsigned long)_etext
;
288 *symbolsize
= symbol_end
- symbol_start
;
290 *offset
= addr
- symbol_start
;
296 * Lookup an address but don't bother to find any names.
298 int kallsyms_lookup_size_offset(unsigned long addr
, unsigned long *symbolsize
,
299 unsigned long *offset
)
301 char namebuf
[KSYM_NAME_LEN
];
303 if (is_ksym_addr(addr
)) {
304 get_symbol_pos(addr
, symbolsize
, offset
);
307 return !!module_address_lookup(addr
, symbolsize
, offset
, NULL
, NULL
, namebuf
) ||
308 !!__bpf_address_lookup(addr
, symbolsize
, offset
, namebuf
);
311 static const char *kallsyms_lookup_buildid(unsigned long addr
,
312 unsigned long *symbolsize
,
313 unsigned long *offset
, char **modname
,
314 const unsigned char **modbuildid
, char *namebuf
)
318 namebuf
[KSYM_NAME_LEN
- 1] = 0;
321 if (is_ksym_addr(addr
)) {
324 pos
= get_symbol_pos(addr
, symbolsize
, offset
);
326 kallsyms_expand_symbol(get_symbol_offset(pos
),
327 namebuf
, KSYM_NAME_LEN
);
337 /* See if it's in a module or a BPF JITed image. */
338 ret
= module_address_lookup(addr
, symbolsize
, offset
,
339 modname
, modbuildid
, namebuf
);
341 ret
= bpf_address_lookup(addr
, symbolsize
,
342 offset
, modname
, namebuf
);
345 ret
= ftrace_mod_address_lookup(addr
, symbolsize
,
346 offset
, modname
, namebuf
);
349 cleanup_symbol_name(namebuf
);
355 * - modname is set to NULL if it's in the kernel.
356 * - We guarantee that the returned name is valid until we reschedule even if.
357 * It resides in a module.
358 * - We also guarantee that modname will be valid until rescheduled.
360 const char *kallsyms_lookup(unsigned long addr
,
361 unsigned long *symbolsize
,
362 unsigned long *offset
,
363 char **modname
, char *namebuf
)
365 return kallsyms_lookup_buildid(addr
, symbolsize
, offset
, modname
,
369 int lookup_symbol_name(unsigned long addr
, char *symname
)
374 symname
[KSYM_NAME_LEN
- 1] = '\0';
376 if (is_ksym_addr(addr
)) {
379 pos
= get_symbol_pos(addr
, NULL
, NULL
);
381 kallsyms_expand_symbol(get_symbol_offset(pos
),
382 symname
, KSYM_NAME_LEN
);
385 /* See if it's in a module. */
386 res
= lookup_module_symbol_name(addr
, symname
);
391 cleanup_symbol_name(symname
);
395 int lookup_symbol_attrs(unsigned long addr
, unsigned long *size
,
396 unsigned long *offset
, char *modname
, char *name
)
401 name
[KSYM_NAME_LEN
- 1] = '\0';
403 if (is_ksym_addr(addr
)) {
406 pos
= get_symbol_pos(addr
, size
, offset
);
408 kallsyms_expand_symbol(get_symbol_offset(pos
),
409 name
, KSYM_NAME_LEN
);
413 /* See if it's in a module. */
414 res
= lookup_module_symbol_attrs(addr
, size
, offset
, modname
, name
);
419 cleanup_symbol_name(name
);
423 /* Look up a kernel symbol and return it in a text buffer. */
424 static int __sprint_symbol(char *buffer
, unsigned long address
,
425 int symbol_offset
, int add_offset
, int add_buildid
)
428 const unsigned char *buildid
;
430 unsigned long offset
, size
;
433 address
+= symbol_offset
;
434 name
= kallsyms_lookup_buildid(address
, &size
, &offset
, &modname
, &buildid
,
437 return sprintf(buffer
, "0x%lx", address
- symbol_offset
);
440 strcpy(buffer
, name
);
441 len
= strlen(buffer
);
442 offset
-= symbol_offset
;
445 len
+= sprintf(buffer
+ len
, "+%#lx/%#lx", offset
, size
);
448 len
+= sprintf(buffer
+ len
, " [%s", modname
);
449 #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
450 if (add_buildid
&& buildid
) {
451 /* build ID should match length of sprintf */
452 #if IS_ENABLED(CONFIG_MODULES)
453 static_assert(sizeof(typeof_member(struct module
, build_id
)) == 20);
455 len
+= sprintf(buffer
+ len
, " %20phN", buildid
);
458 len
+= sprintf(buffer
+ len
, "]");
465 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
466 * @buffer: buffer to be stored
467 * @address: address to lookup
469 * This function looks up a kernel symbol with @address and stores its name,
470 * offset, size and module name to @buffer if possible. If no symbol was found,
471 * just saves its @address as is.
473 * This function returns the number of bytes stored in @buffer.
475 int sprint_symbol(char *buffer
, unsigned long address
)
477 return __sprint_symbol(buffer
, address
, 0, 1, 0);
479 EXPORT_SYMBOL_GPL(sprint_symbol
);
482 * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
483 * @buffer: buffer to be stored
484 * @address: address to lookup
486 * This function looks up a kernel symbol with @address and stores its name,
487 * offset, size, module name and module build ID to @buffer if possible. If no
488 * symbol was found, just saves its @address as is.
490 * This function returns the number of bytes stored in @buffer.
492 int sprint_symbol_build_id(char *buffer
, unsigned long address
)
494 return __sprint_symbol(buffer
, address
, 0, 1, 1);
496 EXPORT_SYMBOL_GPL(sprint_symbol_build_id
);
499 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
500 * @buffer: buffer to be stored
501 * @address: address to lookup
503 * This function looks up a kernel symbol with @address and stores its name
504 * and module name to @buffer if possible. If no symbol was found, just saves
505 * its @address as is.
507 * This function returns the number of bytes stored in @buffer.
509 int sprint_symbol_no_offset(char *buffer
, unsigned long address
)
511 return __sprint_symbol(buffer
, address
, 0, 0, 0);
513 EXPORT_SYMBOL_GPL(sprint_symbol_no_offset
);
516 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
517 * @buffer: buffer to be stored
518 * @address: address to lookup
520 * This function is for stack backtrace and does the same thing as
521 * sprint_symbol() but with modified/decreased @address. If there is a
522 * tail-call to the function marked "noreturn", gcc optimized out code after
523 * the call so that the stack-saved return address could point outside of the
524 * caller. This function ensures that kallsyms will find the original caller
525 * by decreasing @address.
527 * This function returns the number of bytes stored in @buffer.
529 int sprint_backtrace(char *buffer
, unsigned long address
)
531 return __sprint_symbol(buffer
, address
, -1, 1, 0);
535 * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
536 * @buffer: buffer to be stored
537 * @address: address to lookup
539 * This function is for stack backtrace and does the same thing as
540 * sprint_symbol() but with modified/decreased @address. If there is a
541 * tail-call to the function marked "noreturn", gcc optimized out code after
542 * the call so that the stack-saved return address could point outside of the
543 * caller. This function ensures that kallsyms will find the original caller
544 * by decreasing @address. This function also appends the module build ID to
545 * the @buffer if @address is within a kernel module.
547 * This function returns the number of bytes stored in @buffer.
549 int sprint_backtrace_build_id(char *buffer
, unsigned long address
)
551 return __sprint_symbol(buffer
, address
, -1, 1, 1);
554 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
555 struct kallsym_iter
{
559 loff_t pos_ftrace_mod_end
;
562 unsigned int nameoff
; /* If iterating in core kernel symbols. */
564 char name
[KSYM_NAME_LEN
];
565 char module_name
[MODULE_NAME_LEN
];
570 int __weak
arch_get_kallsym(unsigned int symnum
, unsigned long *value
,
571 char *type
, char *name
)
576 static int get_ksymbol_arch(struct kallsym_iter
*iter
)
578 int ret
= arch_get_kallsym(iter
->pos
- kallsyms_num_syms
,
579 &iter
->value
, &iter
->type
,
583 iter
->pos_arch_end
= iter
->pos
;
590 static int get_ksymbol_mod(struct kallsym_iter
*iter
)
592 int ret
= module_get_kallsym(iter
->pos
- iter
->pos_arch_end
,
593 &iter
->value
, &iter
->type
,
594 iter
->name
, iter
->module_name
,
597 iter
->pos_mod_end
= iter
->pos
;
605 * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
606 * purposes. In that case "__builtin__ftrace" is used as a module name, even
607 * though "__builtin__ftrace" is not a module.
609 static int get_ksymbol_ftrace_mod(struct kallsym_iter
*iter
)
611 int ret
= ftrace_mod_get_kallsym(iter
->pos
- iter
->pos_mod_end
,
612 &iter
->value
, &iter
->type
,
613 iter
->name
, iter
->module_name
,
616 iter
->pos_ftrace_mod_end
= iter
->pos
;
623 static int get_ksymbol_bpf(struct kallsym_iter
*iter
)
627 strlcpy(iter
->module_name
, "bpf", MODULE_NAME_LEN
);
629 ret
= bpf_get_kallsym(iter
->pos
- iter
->pos_ftrace_mod_end
,
630 &iter
->value
, &iter
->type
,
633 iter
->pos_bpf_end
= iter
->pos
;
641 * This uses "__builtin__kprobes" as a module name for symbols for pages
642 * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
645 static int get_ksymbol_kprobe(struct kallsym_iter
*iter
)
647 strlcpy(iter
->module_name
, "__builtin__kprobes", MODULE_NAME_LEN
);
649 return kprobe_get_kallsym(iter
->pos
- iter
->pos_bpf_end
,
650 &iter
->value
, &iter
->type
,
651 iter
->name
) < 0 ? 0 : 1;
654 /* Returns space to next name. */
655 static unsigned long get_ksymbol_core(struct kallsym_iter
*iter
)
657 unsigned off
= iter
->nameoff
;
659 iter
->module_name
[0] = '\0';
660 iter
->value
= kallsyms_sym_address(iter
->pos
);
662 iter
->type
= kallsyms_get_symbol_type(off
);
664 off
= kallsyms_expand_symbol(off
, iter
->name
, ARRAY_SIZE(iter
->name
));
666 return off
- iter
->nameoff
;
669 static void reset_iter(struct kallsym_iter
*iter
, loff_t new_pos
)
671 iter
->name
[0] = '\0';
672 iter
->nameoff
= get_symbol_offset(new_pos
);
675 iter
->pos_arch_end
= 0;
676 iter
->pos_mod_end
= 0;
677 iter
->pos_ftrace_mod_end
= 0;
678 iter
->pos_bpf_end
= 0;
683 * The end position (last + 1) of each additional kallsyms section is recorded
684 * in iter->pos_..._end as each section is added, and so can be used to
685 * determine which get_ksymbol_...() function to call next.
687 static int update_iter_mod(struct kallsym_iter
*iter
, loff_t pos
)
691 if ((!iter
->pos_arch_end
|| iter
->pos_arch_end
> pos
) &&
692 get_ksymbol_arch(iter
))
695 if ((!iter
->pos_mod_end
|| iter
->pos_mod_end
> pos
) &&
696 get_ksymbol_mod(iter
))
699 if ((!iter
->pos_ftrace_mod_end
|| iter
->pos_ftrace_mod_end
> pos
) &&
700 get_ksymbol_ftrace_mod(iter
))
703 if ((!iter
->pos_bpf_end
|| iter
->pos_bpf_end
> pos
) &&
704 get_ksymbol_bpf(iter
))
707 return get_ksymbol_kprobe(iter
);
710 /* Returns false if pos at or past end of file. */
711 static int update_iter(struct kallsym_iter
*iter
, loff_t pos
)
713 /* Module symbols can be accessed randomly. */
714 if (pos
>= kallsyms_num_syms
)
715 return update_iter_mod(iter
, pos
);
717 /* If we're not on the desired position, reset to new position. */
718 if (pos
!= iter
->pos
)
719 reset_iter(iter
, pos
);
721 iter
->nameoff
+= get_ksymbol_core(iter
);
727 static void *s_next(struct seq_file
*m
, void *p
, loff_t
*pos
)
731 if (!update_iter(m
->private, *pos
))
736 static void *s_start(struct seq_file
*m
, loff_t
*pos
)
738 if (!update_iter(m
->private, *pos
))
743 static void s_stop(struct seq_file
*m
, void *p
)
747 static int s_show(struct seq_file
*m
, void *p
)
750 struct kallsym_iter
*iter
= m
->private;
752 /* Some debugging symbols have no name. Ignore them. */
756 value
= iter
->show_value
? (void *)iter
->value
: NULL
;
758 if (iter
->module_name
[0]) {
762 * Label it "global" if it is exported,
763 * "local" if not exported.
765 type
= iter
->exported
? toupper(iter
->type
) :
767 seq_printf(m
, "%px %c %s\t[%s]\n", value
,
768 type
, iter
->name
, iter
->module_name
);
770 seq_printf(m
, "%px %c %s\n", value
,
771 iter
->type
, iter
->name
);
775 static const struct seq_operations kallsyms_op
= {
782 #ifdef CONFIG_BPF_SYSCALL
784 struct bpf_iter__ksym
{
785 __bpf_md_ptr(struct bpf_iter_meta
*, meta
);
786 __bpf_md_ptr(struct kallsym_iter
*, ksym
);
789 static int ksym_prog_seq_show(struct seq_file
*m
, bool in_stop
)
791 struct bpf_iter__ksym ctx
;
792 struct bpf_iter_meta meta
;
793 struct bpf_prog
*prog
;
796 prog
= bpf_iter_get_info(&meta
, in_stop
);
801 ctx
.ksym
= m
? m
->private : NULL
;
802 return bpf_iter_run_prog(prog
, &ctx
);
805 static int bpf_iter_ksym_seq_show(struct seq_file
*m
, void *p
)
807 return ksym_prog_seq_show(m
, false);
810 static void bpf_iter_ksym_seq_stop(struct seq_file
*m
, void *p
)
813 (void) ksym_prog_seq_show(m
, true);
818 static const struct seq_operations bpf_iter_ksym_ops
= {
821 .stop
= bpf_iter_ksym_seq_stop
,
822 .show
= bpf_iter_ksym_seq_show
,
825 static int bpf_iter_ksym_init(void *priv_data
, struct bpf_iter_aux_info
*aux
)
827 struct kallsym_iter
*iter
= priv_data
;
831 /* cache here as in kallsyms_open() case; use current process
832 * credentials to tell BPF iterators if values should be shown.
834 iter
->show_value
= kallsyms_show_value(current_cred());
839 DEFINE_BPF_ITER_FUNC(ksym
, struct bpf_iter_meta
*meta
, struct kallsym_iter
*ksym
)
841 static const struct bpf_iter_seq_info ksym_iter_seq_info
= {
842 .seq_ops
= &bpf_iter_ksym_ops
,
843 .init_seq_private
= bpf_iter_ksym_init
,
844 .fini_seq_private
= NULL
,
845 .seq_priv_size
= sizeof(struct kallsym_iter
),
848 static struct bpf_iter_reg ksym_iter_reg_info
= {
850 .feature
= BPF_ITER_RESCHED
,
851 .ctx_arg_info_size
= 1,
853 { offsetof(struct bpf_iter__ksym
, ksym
),
854 PTR_TO_BTF_ID_OR_NULL
},
856 .seq_info
= &ksym_iter_seq_info
,
859 BTF_ID_LIST(btf_ksym_iter_id
)
860 BTF_ID(struct, kallsym_iter
)
862 static int __init
bpf_ksym_iter_register(void)
864 ksym_iter_reg_info
.ctx_arg_info
[0].btf_id
= *btf_ksym_iter_id
;
865 return bpf_iter_reg_target(&ksym_iter_reg_info
);
868 late_initcall(bpf_ksym_iter_register
);
870 #endif /* CONFIG_BPF_SYSCALL */
872 static inline int kallsyms_for_perf(void)
874 #ifdef CONFIG_PERF_EVENTS
875 extern int sysctl_perf_event_paranoid
;
876 if (sysctl_perf_event_paranoid
<= 1)
883 * We show kallsyms information even to normal users if we've enabled
884 * kernel profiling and are explicitly not paranoid (so kptr_restrict
885 * is clear, and sysctl_perf_event_paranoid isn't set).
887 * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
890 bool kallsyms_show_value(const struct cred
*cred
)
892 switch (kptr_restrict
) {
894 if (kallsyms_for_perf())
898 if (security_capable(cred
, &init_user_ns
, CAP_SYSLOG
,
899 CAP_OPT_NOAUDIT
) == 0)
907 static int kallsyms_open(struct inode
*inode
, struct file
*file
)
910 * We keep iterator in m->private, since normal case is to
911 * s_start from where we left off, so we avoid doing
912 * using get_symbol_offset for every symbol.
914 struct kallsym_iter
*iter
;
915 iter
= __seq_open_private(file
, &kallsyms_op
, sizeof(*iter
));
921 * Instead of checking this on every s_show() call, cache
922 * the result here at open time.
924 iter
->show_value
= kallsyms_show_value(file
->f_cred
);
928 #ifdef CONFIG_KGDB_KDB
929 const char *kdb_walk_kallsyms(loff_t
*pos
)
931 static struct kallsym_iter kdb_walk_kallsyms_iter
;
933 memset(&kdb_walk_kallsyms_iter
, 0,
934 sizeof(kdb_walk_kallsyms_iter
));
935 reset_iter(&kdb_walk_kallsyms_iter
, 0);
938 if (!update_iter(&kdb_walk_kallsyms_iter
, *pos
))
941 /* Some debugging symbols have no name. Ignore them. */
942 if (kdb_walk_kallsyms_iter
.name
[0])
943 return kdb_walk_kallsyms_iter
.name
;
946 #endif /* CONFIG_KGDB_KDB */
948 static const struct proc_ops kallsyms_proc_ops
= {
949 .proc_open
= kallsyms_open
,
950 .proc_read
= seq_read
,
951 .proc_lseek
= seq_lseek
,
952 .proc_release
= seq_release_private
,
955 static int __init
kallsyms_init(void)
957 proc_create("kallsyms", 0444, NULL
, &kallsyms_proc_ops
);
960 device_initcall(kallsyms_init
);