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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - scripts/kallsyms.c
1 /* Generate assembler source containing symbol information
3 * Copyright 2002 by Kai Germaschewski
5 * This software may be used and distributed according to the terms
6 * of the GNU General Public License, incorporated herein by reference.
8 * Usage: nm -n vmlinux | scripts/kallsyms [--all-symbols] > symbols.S
10 * Table compression uses all the unused char codes on the symbols and
11 * maps these to the most used substrings (tokens). For instance, it might
12 * map char code 0xF7 to represent "write_" and then in every symbol where
13 * "write_" appears it can be replaced by 0xF7, saving 5 bytes.
14 * The used codes themselves are also placed in the table so that the
15 * decompresion can work without "special cases".
16 * Applied to kernel symbols, this usually produces a compression ratio
28 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
31 #define KSYM_NAME_LEN 128
34 unsigned long long addr
;
36 unsigned int start_pos
;
38 unsigned int percpu_absolute
;
42 const char *start_sym
, *end_sym
;
43 unsigned long long start
, end
;
46 static unsigned long long _text
;
47 static unsigned long long relative_base
;
48 static struct addr_range text_ranges
[] = {
49 { "_stext", "_etext" },
50 { "_sinittext", "_einittext" },
52 #define text_range_text (&text_ranges[0])
53 #define text_range_inittext (&text_ranges[1])
55 static struct addr_range percpu_range
= {
56 "__per_cpu_start", "__per_cpu_end", -1ULL, 0
59 static struct sym_entry
*table
;
60 static unsigned int table_size
, table_cnt
;
61 static int all_symbols
= 0;
62 static int absolute_percpu
= 0;
63 static int base_relative
= 0;
65 static int token_profit
[0x10000];
67 /* the table that holds the result of the compression */
68 static unsigned char best_table
[256][2];
69 static unsigned char best_table_len
[256];
72 static void usage(void)
74 fprintf(stderr
, "Usage: kallsyms [--all-symbols] "
75 "[--base-relative] < in.map > out.S\n");
80 * This ignores the intensely annoying "mapping symbols" found
81 * in ARM ELF files: $a, $t and $d.
83 static int is_arm_mapping_symbol(const char *str
)
85 return str
[0] == '$' && strchr("axtd", str
[1])
86 && (str
[2] == '\0' || str
[2] == '.');
89 static int check_symbol_range(const char *sym
, unsigned long long addr
,
90 struct addr_range
*ranges
, int entries
)
93 struct addr_range
*ar
;
95 for (i
= 0; i
< entries
; ++i
) {
98 if (strcmp(sym
, ar
->start_sym
) == 0) {
101 } else if (strcmp(sym
, ar
->end_sym
) == 0) {
110 static int read_symbol(FILE *in
, struct sym_entry
*s
)
112 char sym
[500], stype
;
115 rc
= fscanf(in
, "%llx %c %499s\n", &s
->addr
, &stype
, sym
);
117 if (rc
!= EOF
&& fgets(sym
, 500, in
) == NULL
)
118 fprintf(stderr
, "Read error or end of file.\n");
121 if (strlen(sym
) >= KSYM_NAME_LEN
) {
122 fprintf(stderr
, "Symbol %s too long for kallsyms (%zu >= %d).\n"
123 "Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",
124 sym
, strlen(sym
), KSYM_NAME_LEN
);
128 /* Ignore most absolute/undefined (?) symbols. */
129 if (strcmp(sym
, "_text") == 0)
131 else if (check_symbol_range(sym
, s
->addr
, text_ranges
,
132 ARRAY_SIZE(text_ranges
)) == 0)
134 else if (toupper(stype
) == 'A')
136 /* Keep these useful absolute symbols */
137 if (strcmp(sym
, "__kernel_syscall_via_break") &&
138 strcmp(sym
, "__kernel_syscall_via_epc") &&
139 strcmp(sym
, "__kernel_sigtramp") &&
144 else if (toupper(stype
) == 'U' ||
145 is_arm_mapping_symbol(sym
))
147 /* exclude also MIPS ELF local symbols ($L123 instead of .L123) */
148 else if (sym
[0] == '$')
150 /* exclude debugging symbols */
151 else if (stype
== 'N' || stype
== 'n')
154 /* include the type field in the symbol name, so that it gets
155 * compressed together */
156 s
->len
= strlen(sym
) + 1;
157 s
->sym
= malloc(s
->len
+ 1);
159 fprintf(stderr
, "kallsyms failure: "
160 "unable to allocate required amount of memory\n");
163 strcpy((char *)s
->sym
+ 1, sym
);
166 s
->percpu_absolute
= 0;
168 /* Record if we've found __per_cpu_start/end. */
169 check_symbol_range(sym
, s
->addr
, &percpu_range
, 1);
174 static int symbol_in_range(struct sym_entry
*s
, struct addr_range
*ranges
,
178 struct addr_range
*ar
;
180 for (i
= 0; i
< entries
; ++i
) {
183 if (s
->addr
>= ar
->start
&& s
->addr
<= ar
->end
)
190 static int symbol_valid(struct sym_entry
*s
)
192 /* Symbols which vary between passes. Passes 1 and 2 must have
193 * identical symbol lists. The kallsyms_* symbols below are only added
194 * after pass 1, they would be included in pass 2 when --all-symbols is
195 * specified so exclude them to get a stable symbol list.
197 static char *special_symbols
[] = {
198 "kallsyms_addresses",
200 "kallsyms_relative_base",
204 "kallsyms_token_table",
205 "kallsyms_token_index",
207 /* Exclude linker generated symbols which vary between passes */
208 "_SDA_BASE_", /* ppc */
209 "_SDA2_BASE_", /* ppc */
212 static char *special_prefixes
[] = {
213 "__crc_", /* modversions */
214 "__efistub_", /* arm64 EFI stub namespace */
217 static char *special_suffixes
[] = {
219 "_from_arm", /* arm */
220 "_from_thumb", /* arm */
224 char *sym_name
= (char *)s
->sym
+ 1;
226 /* if --all-symbols is not specified, then symbols outside the text
227 * and inittext sections are discarded */
229 if (symbol_in_range(s
, text_ranges
,
230 ARRAY_SIZE(text_ranges
)) == 0)
232 /* Corner case. Discard any symbols with the same value as
233 * _etext _einittext; they can move between pass 1 and 2 when
234 * the kallsyms data are added. If these symbols move then
235 * they may get dropped in pass 2, which breaks the kallsyms
238 if ((s
->addr
== text_range_text
->end
&&
240 text_range_text
->end_sym
)) ||
241 (s
->addr
== text_range_inittext
->end
&&
243 text_range_inittext
->end_sym
)))
247 /* Exclude symbols which vary between passes. */
248 for (i
= 0; special_symbols
[i
]; i
++)
249 if (strcmp(sym_name
, special_symbols
[i
]) == 0)
252 for (i
= 0; special_prefixes
[i
]; i
++) {
253 int l
= strlen(special_prefixes
[i
]);
255 if (l
<= strlen(sym_name
) &&
256 strncmp(sym_name
, special_prefixes
[i
], l
) == 0)
260 for (i
= 0; special_suffixes
[i
]; i
++) {
261 int l
= strlen(sym_name
) - strlen(special_suffixes
[i
]);
263 if (l
>= 0 && strcmp(sym_name
+ l
, special_suffixes
[i
]) == 0)
270 static void read_map(FILE *in
)
273 if (table_cnt
>= table_size
) {
275 table
= realloc(table
, sizeof(*table
) * table_size
);
277 fprintf(stderr
, "out of memory\n");
281 if (read_symbol(in
, &table
[table_cnt
]) == 0) {
282 table
[table_cnt
].start_pos
= table_cnt
;
288 static void output_label(char *label
)
290 printf(".globl %s\n", label
);
292 printf("%s:\n", label
);
295 /* uncompress a compressed symbol. When this function is called, the best table
296 * might still be compressed itself, so the function needs to be recursive */
297 static int expand_symbol(unsigned char *data
, int len
, char *result
)
299 int c
, rlen
, total
=0;
303 /* if the table holds a single char that is the same as the one
304 * we are looking for, then end the search */
305 if (best_table
[c
][0]==c
&& best_table_len
[c
]==1) {
309 /* if not, recurse and expand */
310 rlen
= expand_symbol(best_table
[c
], best_table_len
[c
], result
);
322 static int symbol_absolute(struct sym_entry
*s
)
324 return s
->percpu_absolute
;
327 static void write_src(void)
329 unsigned int i
, k
, off
;
330 unsigned int best_idx
[256];
331 unsigned int *markers
;
332 char buf
[KSYM_NAME_LEN
];
334 printf("#include <asm/bitsperlong.h>\n");
335 printf("#if BITS_PER_LONG == 64\n");
336 printf("#define PTR .quad\n");
337 printf("#define ALGN .balign 8\n");
339 printf("#define PTR .long\n");
340 printf("#define ALGN .balign 4\n");
343 printf("\t.section .rodata, \"a\"\n");
345 /* Provide proper symbols relocatability by their relativeness
346 * to a fixed anchor point in the runtime image, either '_text'
347 * for absolute address tables, in which case the linker will
348 * emit the final addresses at build time. Otherwise, use the
349 * offset relative to the lowest value encountered of all relative
350 * symbols, and emit non-relocatable fixed offsets that will be fixed
353 * The symbol names cannot be used to construct normal symbol
354 * references as the list of symbols contains symbols that are
355 * declared static and are private to their .o files. This prevents
356 * .tmp_kallsyms.o or any other object from referencing them.
359 output_label("kallsyms_addresses");
361 output_label("kallsyms_offsets");
363 for (i
= 0; i
< table_cnt
; i
++) {
368 if (!absolute_percpu
) {
369 offset
= table
[i
].addr
- relative_base
;
370 overflow
= (offset
< 0 || offset
> UINT_MAX
);
371 } else if (symbol_absolute(&table
[i
])) {
372 offset
= table
[i
].addr
;
373 overflow
= (offset
< 0 || offset
> INT_MAX
);
375 offset
= relative_base
- table
[i
].addr
- 1;
376 overflow
= (offset
< INT_MIN
|| offset
>= 0);
379 fprintf(stderr
, "kallsyms failure: "
380 "%s symbol value %#llx out of range in relative mode\n",
381 symbol_absolute(&table
[i
]) ? "absolute" : "relative",
385 printf("\t.long\t%#x\n", (int)offset
);
386 } else if (!symbol_absolute(&table
[i
])) {
387 if (_text
<= table
[i
].addr
)
388 printf("\tPTR\t_text + %#llx\n",
389 table
[i
].addr
- _text
);
391 printf("\tPTR\t_text - %#llx\n",
392 _text
- table
[i
].addr
);
394 printf("\tPTR\t%#llx\n", table
[i
].addr
);
400 output_label("kallsyms_relative_base");
401 printf("\tPTR\t_text - %#llx\n", _text
- relative_base
);
405 output_label("kallsyms_num_syms");
406 printf("\t.long\t%u\n", table_cnt
);
409 /* table of offset markers, that give the offset in the compressed stream
410 * every 256 symbols */
411 markers
= malloc(sizeof(unsigned int) * ((table_cnt
+ 255) / 256));
413 fprintf(stderr
, "kallsyms failure: "
414 "unable to allocate required memory\n");
418 output_label("kallsyms_names");
420 for (i
= 0; i
< table_cnt
; i
++) {
422 markers
[i
>> 8] = off
;
424 printf("\t.byte 0x%02x", table
[i
].len
);
425 for (k
= 0; k
< table
[i
].len
; k
++)
426 printf(", 0x%02x", table
[i
].sym
[k
]);
429 off
+= table
[i
].len
+ 1;
433 output_label("kallsyms_markers");
434 for (i
= 0; i
< ((table_cnt
+ 255) >> 8); i
++)
435 printf("\t.long\t%u\n", markers
[i
]);
440 output_label("kallsyms_token_table");
442 for (i
= 0; i
< 256; i
++) {
444 expand_symbol(best_table
[i
], best_table_len
[i
], buf
);
445 printf("\t.asciz\t\"%s\"\n", buf
);
446 off
+= strlen(buf
) + 1;
450 output_label("kallsyms_token_index");
451 for (i
= 0; i
< 256; i
++)
452 printf("\t.short\t%d\n", best_idx
[i
]);
457 /* table lookup compression functions */
459 /* count all the possible tokens in a symbol */
460 static void learn_symbol(unsigned char *symbol
, int len
)
464 for (i
= 0; i
< len
- 1; i
++)
465 token_profit
[ symbol
[i
] + (symbol
[i
+ 1] << 8) ]++;
468 /* decrease the count for all the possible tokens in a symbol */
469 static void forget_symbol(unsigned char *symbol
, int len
)
473 for (i
= 0; i
< len
- 1; i
++)
474 token_profit
[ symbol
[i
] + (symbol
[i
+ 1] << 8) ]--;
477 /* remove all the invalid symbols from the table and do the initial token count */
478 static void build_initial_tok_table(void)
483 for (i
= 0; i
< table_cnt
; i
++) {
484 if ( symbol_valid(&table
[i
]) ) {
486 table
[pos
] = table
[i
];
487 learn_symbol(table
[pos
].sym
, table
[pos
].len
);
494 static void *find_token(unsigned char *str
, int len
, unsigned char *token
)
498 for (i
= 0; i
< len
- 1; i
++) {
499 if (str
[i
] == token
[0] && str
[i
+1] == token
[1])
505 /* replace a given token in all the valid symbols. Use the sampled symbols
506 * to update the counts */
507 static void compress_symbols(unsigned char *str
, int idx
)
509 unsigned int i
, len
, size
;
510 unsigned char *p1
, *p2
;
512 for (i
= 0; i
< table_cnt
; i
++) {
517 /* find the token on the symbol */
518 p2
= find_token(p1
, len
, str
);
521 /* decrease the counts for this symbol's tokens */
522 forget_symbol(table
[i
].sym
, len
);
530 memmove(p2
, p2
+ 1, size
);
536 /* find the token on the symbol */
537 p2
= find_token(p1
, size
, str
);
543 /* increase the counts for this symbol's new tokens */
544 learn_symbol(table
[i
].sym
, len
);
548 /* search the token with the maximum profit */
549 static int find_best_token(void)
551 int i
, best
, bestprofit
;
556 for (i
= 0; i
< 0x10000; i
++) {
557 if (token_profit
[i
] > bestprofit
) {
559 bestprofit
= token_profit
[i
];
565 /* this is the core of the algorithm: calculate the "best" table */
566 static void optimize_result(void)
570 /* using the '\0' symbol last allows compress_symbols to use standard
571 * fast string functions */
572 for (i
= 255; i
>= 0; i
--) {
574 /* if this table slot is empty (it is not used by an actual
575 * original char code */
576 if (!best_table_len
[i
]) {
578 /* find the token with the best profit value */
579 best
= find_best_token();
580 if (token_profit
[best
] == 0)
583 /* place it in the "best" table */
584 best_table_len
[i
] = 2;
585 best_table
[i
][0] = best
& 0xFF;
586 best_table
[i
][1] = (best
>> 8) & 0xFF;
588 /* replace this token in all the valid symbols */
589 compress_symbols(best_table
[i
], i
);
594 /* start by placing the symbols that are actually used on the table */
595 static void insert_real_symbols_in_table(void)
597 unsigned int i
, j
, c
;
599 for (i
= 0; i
< table_cnt
; i
++) {
600 for (j
= 0; j
< table
[i
].len
; j
++) {
608 static void optimize_token_table(void)
610 build_initial_tok_table();
612 insert_real_symbols_in_table();
614 /* When valid symbol is not registered, exit to error */
616 fprintf(stderr
, "No valid symbol.\n");
623 /* guess for "linker script provide" symbol */
624 static int may_be_linker_script_provide_symbol(const struct sym_entry
*se
)
626 const char *symbol
= (char *)se
->sym
+ 1;
627 int len
= se
->len
- 1;
632 if (symbol
[0] != '_' || symbol
[1] != '_')
636 if (!memcmp(symbol
+ 2, "start_", 6))
640 if (!memcmp(symbol
+ 2, "stop_", 5))
644 if (!memcmp(symbol
+ 2, "end_", 4))
648 if (!memcmp(symbol
+ len
- 6, "_start", 6))
652 if (!memcmp(symbol
+ len
- 4, "_end", 4))
658 static int prefix_underscores_count(const char *str
)
660 const char *tail
= str
;
668 static int compare_symbols(const void *a
, const void *b
)
670 const struct sym_entry
*sa
;
671 const struct sym_entry
*sb
;
677 /* sort by address first */
678 if (sa
->addr
> sb
->addr
)
680 if (sa
->addr
< sb
->addr
)
683 /* sort by "weakness" type */
684 wa
= (sa
->sym
[0] == 'w') || (sa
->sym
[0] == 'W');
685 wb
= (sb
->sym
[0] == 'w') || (sb
->sym
[0] == 'W');
689 /* sort by "linker script provide" type */
690 wa
= may_be_linker_script_provide_symbol(sa
);
691 wb
= may_be_linker_script_provide_symbol(sb
);
695 /* sort by the number of prefix underscores */
696 wa
= prefix_underscores_count((const char *)sa
->sym
+ 1);
697 wb
= prefix_underscores_count((const char *)sb
->sym
+ 1);
701 /* sort by initial order, so that other symbols are left undisturbed */
702 return sa
->start_pos
- sb
->start_pos
;
705 static void sort_symbols(void)
707 qsort(table
, table_cnt
, sizeof(struct sym_entry
), compare_symbols
);
710 static void make_percpus_absolute(void)
714 for (i
= 0; i
< table_cnt
; i
++)
715 if (symbol_in_range(&table
[i
], &percpu_range
, 1)) {
717 * Keep the 'A' override for percpu symbols to
718 * ensure consistent behavior compared to older
719 * versions of this tool.
721 table
[i
].sym
[0] = 'A';
722 table
[i
].percpu_absolute
= 1;
726 /* find the minimum non-absolute symbol address */
727 static void record_relative_base(void)
731 relative_base
= -1ULL;
732 for (i
= 0; i
< table_cnt
; i
++)
733 if (!symbol_absolute(&table
[i
]) &&
734 table
[i
].addr
< relative_base
)
735 relative_base
= table
[i
].addr
;
738 int main(int argc
, char **argv
)
742 for (i
= 1; i
< argc
; i
++) {
743 if(strcmp(argv
[i
], "--all-symbols") == 0)
745 else if (strcmp(argv
[i
], "--absolute-percpu") == 0)
747 else if (strcmp(argv
[i
], "--base-relative") == 0)
752 } else if (argc
!= 1)
757 make_percpus_absolute();
759 record_relative_base();
761 optimize_token_table();