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1/* Generate assembler source containing symbol information
2 *
3 * Copyright 2002 by Kai Germaschewski
4 *
5 * This software may be used and distributed according to the terms
6 * of the GNU General Public License, incorporated herein by reference.
7 *
8 * Usage: nm -n vmlinux | scripts/kallsyms [--all-symbols] > symbols.S
9 *
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
17 * of about 50%.
18 *
19 */
20
21#include <stdio.h>
22#include <stdlib.h>
23#include <string.h>
24#include <ctype.h>
25
26#ifndef ARRAY_SIZE
27#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
28#endif
29
30#define KSYM_NAME_LEN 128
31
32struct sym_entry {
33 unsigned long long addr;
34 unsigned int len;
35 unsigned int start_pos;
36 unsigned char *sym;
37};
38
39struct text_range {
40 const char *stext, *etext;
41 unsigned long long start, end;
42};
43
44static unsigned long long _text;
45static struct text_range text_ranges[] = {
46 { "_stext", "_etext" },
47 { "_sinittext", "_einittext" },
48 { "_stext_l1", "_etext_l1" }, /* Blackfin on-chip L1 inst SRAM */
49 { "_stext_l2", "_etext_l2" }, /* Blackfin on-chip L2 SRAM */
50};
51#define text_range_text (&text_ranges[0])
52#define text_range_inittext (&text_ranges[1])
53
54static struct sym_entry *table;
55static unsigned int table_size, table_cnt;
56static int all_symbols = 0;
57static char symbol_prefix_char = '\0';
58
59int token_profit[0x10000];
60
61/* the table that holds the result of the compression */
62unsigned char best_table[256][2];
63unsigned char best_table_len[256];
64
65
66static void usage(void)
67{
68 fprintf(stderr, "Usage: kallsyms [--all-symbols] [--symbol-prefix=<prefix char>] < in.map > out.S\n");
69 exit(1);
70}
71
72/*
73 * This ignores the intensely annoying "mapping symbols" found
74 * in ARM ELF files: $a, $t and $d.
75 */
76static inline int is_arm_mapping_symbol(const char *str)
77{
78 return str[0] == '$' && strchr("atd", str[1])
79 && (str[2] == '\0' || str[2] == '.');
80}
81
82static int read_symbol_tr(const char *sym, unsigned long long addr)
83{
84 size_t i;
85 struct text_range *tr;
86
87 for (i = 0; i < ARRAY_SIZE(text_ranges); ++i) {
88 tr = &text_ranges[i];
89
90 if (strcmp(sym, tr->stext) == 0) {
91 tr->start = addr;
92 return 0;
93 } else if (strcmp(sym, tr->etext) == 0) {
94 tr->end = addr;
95 return 0;
96 }
97 }
98
99 return 1;
100}
101
102static int read_symbol(FILE *in, struct sym_entry *s)
103{
104 char str[500];
105 char *sym, stype;
106 int rc;
107
108 rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str);
109 if (rc != 3) {
110 if (rc != EOF && fgets(str, 500, in) == NULL)
111 fprintf(stderr, "Read error or end of file.\n");
112 return -1;
113 }
114
115 sym = str;
116 /* skip prefix char */
117 if (symbol_prefix_char && str[0] == symbol_prefix_char)
118 sym++;
119
120 /* Ignore most absolute/undefined (?) symbols. */
121 if (strcmp(sym, "_text") == 0)
122 _text = s->addr;
123 else if (read_symbol_tr(sym, s->addr) == 0)
124 /* nothing to do */;
125 else if (toupper(stype) == 'A')
126 {
127 /* Keep these useful absolute symbols */
128 if (strcmp(sym, "__kernel_syscall_via_break") &&
129 strcmp(sym, "__kernel_syscall_via_epc") &&
130 strcmp(sym, "__kernel_sigtramp") &&
131 strcmp(sym, "__gp"))
132 return -1;
133
134 }
135 else if (toupper(stype) == 'U' ||
136 is_arm_mapping_symbol(sym))
137 return -1;
138 /* exclude also MIPS ELF local symbols ($L123 instead of .L123) */
139 else if (str[0] == '$')
140 return -1;
141 /* exclude debugging symbols */
142 else if (stype == 'N')
143 return -1;
144
145 /* include the type field in the symbol name, so that it gets
146 * compressed together */
147 s->len = strlen(str) + 1;
148 s->sym = malloc(s->len + 1);
149 if (!s->sym) {
150 fprintf(stderr, "kallsyms failure: "
151 "unable to allocate required amount of memory\n");
152 exit(EXIT_FAILURE);
153 }
154 strcpy((char *)s->sym + 1, str);
155 s->sym[0] = stype;
156
157 return 0;
158}
159
160static int symbol_valid_tr(struct sym_entry *s)
161{
162 size_t i;
163 struct text_range *tr;
164
165 for (i = 0; i < ARRAY_SIZE(text_ranges); ++i) {
166 tr = &text_ranges[i];
167
168 if (s->addr >= tr->start && s->addr <= tr->end)
169 return 1;
170 }
171
172 return 0;
173}
174
175static int symbol_valid(struct sym_entry *s)
176{
177 /* Symbols which vary between passes. Passes 1 and 2 must have
178 * identical symbol lists. The kallsyms_* symbols below are only added
179 * after pass 1, they would be included in pass 2 when --all-symbols is
180 * specified so exclude them to get a stable symbol list.
181 */
182 static char *special_symbols[] = {
183 "kallsyms_addresses",
184 "kallsyms_num_syms",
185 "kallsyms_names",
186 "kallsyms_markers",
187 "kallsyms_token_table",
188 "kallsyms_token_index",
189
190 /* Exclude linker generated symbols which vary between passes */
191 "_SDA_BASE_", /* ppc */
192 "_SDA2_BASE_", /* ppc */
193 NULL };
194 int i;
195 int offset = 1;
196
197 /* skip prefix char */
198 if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char)
199 offset++;
200
201 /* if --all-symbols is not specified, then symbols outside the text
202 * and inittext sections are discarded */
203 if (!all_symbols) {
204 if (symbol_valid_tr(s) == 0)
205 return 0;
206 /* Corner case. Discard any symbols with the same value as
207 * _etext _einittext; they can move between pass 1 and 2 when
208 * the kallsyms data are added. If these symbols move then
209 * they may get dropped in pass 2, which breaks the kallsyms
210 * rules.
211 */
212 if ((s->addr == text_range_text->end &&
213 strcmp((char *)s->sym + offset, text_range_text->etext)) ||
214 (s->addr == text_range_inittext->end &&
215 strcmp((char *)s->sym + offset, text_range_inittext->etext)))
216 return 0;
217 }
218
219 /* Exclude symbols which vary between passes. */
220 if (strstr((char *)s->sym + offset, "_compiled."))
221 return 0;
222
223 for (i = 0; special_symbols[i]; i++)
224 if( strcmp((char *)s->sym + offset, special_symbols[i]) == 0 )
225 return 0;
226
227 return 1;
228}
229
230static void read_map(FILE *in)
231{
232 while (!feof(in)) {
233 if (table_cnt >= table_size) {
234 table_size += 10000;
235 table = realloc(table, sizeof(*table) * table_size);
236 if (!table) {
237 fprintf(stderr, "out of memory\n");
238 exit (1);
239 }
240 }
241 if (read_symbol(in, &table[table_cnt]) == 0) {
242 table[table_cnt].start_pos = table_cnt;
243 table_cnt++;
244 }
245 }
246}
247
248static void output_label(char *label)
249{
250 if (symbol_prefix_char)
251 printf(".globl %c%s\n", symbol_prefix_char, label);
252 else
253 printf(".globl %s\n", label);
254 printf("\tALGN\n");
255 if (symbol_prefix_char)
256 printf("%c%s:\n", symbol_prefix_char, label);
257 else
258 printf("%s:\n", label);
259}
260
261/* uncompress a compressed symbol. When this function is called, the best table
262 * might still be compressed itself, so the function needs to be recursive */
263static int expand_symbol(unsigned char *data, int len, char *result)
264{
265 int c, rlen, total=0;
266
267 while (len) {
268 c = *data;
269 /* if the table holds a single char that is the same as the one
270 * we are looking for, then end the search */
271 if (best_table[c][0]==c && best_table_len[c]==1) {
272 *result++ = c;
273 total++;
274 } else {
275 /* if not, recurse and expand */
276 rlen = expand_symbol(best_table[c], best_table_len[c], result);
277 total += rlen;
278 result += rlen;
279 }
280 data++;
281 len--;
282 }
283 *result=0;
284
285 return total;
286}
287
288static void write_src(void)
289{
290 unsigned int i, k, off;
291 unsigned int best_idx[256];
292 unsigned int *markers;
293 char buf[KSYM_NAME_LEN];
294
295 printf("#include <asm/types.h>\n");
296 printf("#if BITS_PER_LONG == 64\n");
297 printf("#define PTR .quad\n");
298 printf("#define ALGN .align 8\n");
299 printf("#else\n");
300 printf("#define PTR .long\n");
301 printf("#define ALGN .align 4\n");
302 printf("#endif\n");
303
304 printf("\t.section .rodata, \"a\"\n");
305
306 /* Provide proper symbols relocatability by their '_text'
307 * relativeness. The symbol names cannot be used to construct
308 * normal symbol references as the list of symbols contains
309 * symbols that are declared static and are private to their
310 * .o files. This prevents .tmp_kallsyms.o or any other
311 * object from referencing them.
312 */
313 output_label("kallsyms_addresses");
314 for (i = 0; i < table_cnt; i++) {
315 if (toupper(table[i].sym[0]) != 'A') {
316 if (_text <= table[i].addr)
317 printf("\tPTR\t_text + %#llx\n",
318 table[i].addr - _text);
319 else
320 printf("\tPTR\t_text - %#llx\n",
321 _text - table[i].addr);
322 } else {
323 printf("\tPTR\t%#llx\n", table[i].addr);
324 }
325 }
326 printf("\n");
327
328 output_label("kallsyms_num_syms");
329 printf("\tPTR\t%d\n", table_cnt);
330 printf("\n");
331
332 /* table of offset markers, that give the offset in the compressed stream
333 * every 256 symbols */
334 markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
335 if (!markers) {
336 fprintf(stderr, "kallsyms failure: "
337 "unable to allocate required memory\n");
338 exit(EXIT_FAILURE);
339 }
340
341 output_label("kallsyms_names");
342 off = 0;
343 for (i = 0; i < table_cnt; i++) {
344 if ((i & 0xFF) == 0)
345 markers[i >> 8] = off;
346
347 printf("\t.byte 0x%02x", table[i].len);
348 for (k = 0; k < table[i].len; k++)
349 printf(", 0x%02x", table[i].sym[k]);
350 printf("\n");
351
352 off += table[i].len + 1;
353 }
354 printf("\n");
355
356 output_label("kallsyms_markers");
357 for (i = 0; i < ((table_cnt + 255) >> 8); i++)
358 printf("\tPTR\t%d\n", markers[i]);
359 printf("\n");
360
361 free(markers);
362
363 output_label("kallsyms_token_table");
364 off = 0;
365 for (i = 0; i < 256; i++) {
366 best_idx[i] = off;
367 expand_symbol(best_table[i], best_table_len[i], buf);
368 printf("\t.asciz\t\"%s\"\n", buf);
369 off += strlen(buf) + 1;
370 }
371 printf("\n");
372
373 output_label("kallsyms_token_index");
374 for (i = 0; i < 256; i++)
375 printf("\t.short\t%d\n", best_idx[i]);
376 printf("\n");
377}
378
379
380/* table lookup compression functions */
381
382/* count all the possible tokens in a symbol */
383static void learn_symbol(unsigned char *symbol, int len)
384{
385 int i;
386
387 for (i = 0; i < len - 1; i++)
388 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
389}
390
391/* decrease the count for all the possible tokens in a symbol */
392static void forget_symbol(unsigned char *symbol, int len)
393{
394 int i;
395
396 for (i = 0; i < len - 1; i++)
397 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
398}
399
400/* remove all the invalid symbols from the table and do the initial token count */
401static void build_initial_tok_table(void)
402{
403 unsigned int i, pos;
404
405 pos = 0;
406 for (i = 0; i < table_cnt; i++) {
407 if ( symbol_valid(&table[i]) ) {
408 if (pos != i)
409 table[pos] = table[i];
410 learn_symbol(table[pos].sym, table[pos].len);
411 pos++;
412 }
413 }
414 table_cnt = pos;
415}
416
417static void *find_token(unsigned char *str, int len, unsigned char *token)
418{
419 int i;
420
421 for (i = 0; i < len - 1; i++) {
422 if (str[i] == token[0] && str[i+1] == token[1])
423 return &str[i];
424 }
425 return NULL;
426}
427
428/* replace a given token in all the valid symbols. Use the sampled symbols
429 * to update the counts */
430static void compress_symbols(unsigned char *str, int idx)
431{
432 unsigned int i, len, size;
433 unsigned char *p1, *p2;
434
435 for (i = 0; i < table_cnt; i++) {
436
437 len = table[i].len;
438 p1 = table[i].sym;
439
440 /* find the token on the symbol */
441 p2 = find_token(p1, len, str);
442 if (!p2) continue;
443
444 /* decrease the counts for this symbol's tokens */
445 forget_symbol(table[i].sym, len);
446
447 size = len;
448
449 do {
450 *p2 = idx;
451 p2++;
452 size -= (p2 - p1);
453 memmove(p2, p2 + 1, size);
454 p1 = p2;
455 len--;
456
457 if (size < 2) break;
458
459 /* find the token on the symbol */
460 p2 = find_token(p1, size, str);
461
462 } while (p2);
463
464 table[i].len = len;
465
466 /* increase the counts for this symbol's new tokens */
467 learn_symbol(table[i].sym, len);
468 }
469}
470
471/* search the token with the maximum profit */
472static int find_best_token(void)
473{
474 int i, best, bestprofit;
475
476 bestprofit=-10000;
477 best = 0;
478
479 for (i = 0; i < 0x10000; i++) {
480 if (token_profit[i] > bestprofit) {
481 best = i;
482 bestprofit = token_profit[i];
483 }
484 }
485 return best;
486}
487
488/* this is the core of the algorithm: calculate the "best" table */
489static void optimize_result(void)
490{
491 int i, best;
492
493 /* using the '\0' symbol last allows compress_symbols to use standard
494 * fast string functions */
495 for (i = 255; i >= 0; i--) {
496
497 /* if this table slot is empty (it is not used by an actual
498 * original char code */
499 if (!best_table_len[i]) {
500
501 /* find the token with the breates profit value */
502 best = find_best_token();
503 if (token_profit[best] == 0)
504 break;
505
506 /* place it in the "best" table */
507 best_table_len[i] = 2;
508 best_table[i][0] = best & 0xFF;
509 best_table[i][1] = (best >> 8) & 0xFF;
510
511 /* replace this token in all the valid symbols */
512 compress_symbols(best_table[i], i);
513 }
514 }
515}
516
517/* start by placing the symbols that are actually used on the table */
518static void insert_real_symbols_in_table(void)
519{
520 unsigned int i, j, c;
521
522 memset(best_table, 0, sizeof(best_table));
523 memset(best_table_len, 0, sizeof(best_table_len));
524
525 for (i = 0; i < table_cnt; i++) {
526 for (j = 0; j < table[i].len; j++) {
527 c = table[i].sym[j];
528 best_table[c][0]=c;
529 best_table_len[c]=1;
530 }
531 }
532}
533
534static void optimize_token_table(void)
535{
536 build_initial_tok_table();
537
538 insert_real_symbols_in_table();
539
540 /* When valid symbol is not registered, exit to error */
541 if (!table_cnt) {
542 fprintf(stderr, "No valid symbol.\n");
543 exit(1);
544 }
545
546 optimize_result();
547}
548
549/* guess for "linker script provide" symbol */
550static int may_be_linker_script_provide_symbol(const struct sym_entry *se)
551{
552 const char *symbol = (char *)se->sym + 1;
553 int len = se->len - 1;
554
555 if (len < 8)
556 return 0;
557
558 if (symbol[0] != '_' || symbol[1] != '_')
559 return 0;
560
561 /* __start_XXXXX */
562 if (!memcmp(symbol + 2, "start_", 6))
563 return 1;
564
565 /* __stop_XXXXX */
566 if (!memcmp(symbol + 2, "stop_", 5))
567 return 1;
568
569 /* __end_XXXXX */
570 if (!memcmp(symbol + 2, "end_", 4))
571 return 1;
572
573 /* __XXXXX_start */
574 if (!memcmp(symbol + len - 6, "_start", 6))
575 return 1;
576
577 /* __XXXXX_end */
578 if (!memcmp(symbol + len - 4, "_end", 4))
579 return 1;
580
581 return 0;
582}
583
584static int prefix_underscores_count(const char *str)
585{
586 const char *tail = str;
587
588 while (*tail == '_')
589 tail++;
590
591 return tail - str;
592}
593
594static int compare_symbols(const void *a, const void *b)
595{
596 const struct sym_entry *sa;
597 const struct sym_entry *sb;
598 int wa, wb;
599
600 sa = a;
601 sb = b;
602
603 /* sort by address first */
604 if (sa->addr > sb->addr)
605 return 1;
606 if (sa->addr < sb->addr)
607 return -1;
608
609 /* sort by "weakness" type */
610 wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
611 wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
612 if (wa != wb)
613 return wa - wb;
614
615 /* sort by "linker script provide" type */
616 wa = may_be_linker_script_provide_symbol(sa);
617 wb = may_be_linker_script_provide_symbol(sb);
618 if (wa != wb)
619 return wa - wb;
620
621 /* sort by the number of prefix underscores */
622 wa = prefix_underscores_count((const char *)sa->sym + 1);
623 wb = prefix_underscores_count((const char *)sb->sym + 1);
624 if (wa != wb)
625 return wa - wb;
626
627 /* sort by initial order, so that other symbols are left undisturbed */
628 return sa->start_pos - sb->start_pos;
629}
630
631static void sort_symbols(void)
632{
633 qsort(table, table_cnt, sizeof(struct sym_entry), compare_symbols);
634}
635
636int main(int argc, char **argv)
637{
638 if (argc >= 2) {
639 int i;
640 for (i = 1; i < argc; i++) {
641 if(strcmp(argv[i], "--all-symbols") == 0)
642 all_symbols = 1;
643 else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) {
644 char *p = &argv[i][16];
645 /* skip quote */
646 if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
647 p++;
648 symbol_prefix_char = *p;
649 } else
650 usage();
651 }
652 } else if (argc != 1)
653 usage();
654
655 read_map(stdin);
656 sort_symbols();
657 optimize_token_table();
658 write_src();
659
660 return 0;
661}
1/* Generate assembler source containing symbol information
2 *
3 * Copyright 2002 by Kai Germaschewski
4 *
5 * This software may be used and distributed according to the terms
6 * of the GNU General Public License, incorporated herein by reference.
7 *
8 * Usage: nm -n vmlinux | scripts/kallsyms [--all-symbols] > symbols.S
9 *
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
17 * of about 50%.
18 *
19 */
20
21#include <stdbool.h>
22#include <stdio.h>
23#include <stdlib.h>
24#include <string.h>
25#include <ctype.h>
26#include <limits.h>
27
28#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
29
30#define KSYM_NAME_LEN 128
31
32struct sym_entry {
33 unsigned long long addr;
34 unsigned int len;
35 unsigned int start_pos;
36 unsigned int percpu_absolute;
37 unsigned char sym[];
38};
39
40struct addr_range {
41 const char *start_sym, *end_sym;
42 unsigned long long start, end;
43};
44
45static unsigned long long _text;
46static unsigned long long relative_base;
47static struct addr_range text_ranges[] = {
48 { "_stext", "_etext" },
49 { "_sinittext", "_einittext" },
50};
51#define text_range_text (&text_ranges[0])
52#define text_range_inittext (&text_ranges[1])
53
54static struct addr_range percpu_range = {
55 "__per_cpu_start", "__per_cpu_end", -1ULL, 0
56};
57
58static struct sym_entry **table;
59static unsigned int table_size, table_cnt;
60static int all_symbols;
61static int absolute_percpu;
62static int base_relative;
63
64static int token_profit[0x10000];
65
66/* the table that holds the result of the compression */
67static unsigned char best_table[256][2];
68static unsigned char best_table_len[256];
69
70
71static void usage(void)
72{
73 fprintf(stderr, "Usage: kallsyms [--all-symbols] "
74 "[--base-relative] < in.map > out.S\n");
75 exit(1);
76}
77
78static char *sym_name(const struct sym_entry *s)
79{
80 return (char *)s->sym + 1;
81}
82
83static bool is_ignored_symbol(const char *name, char type)
84{
85 /* Symbol names that exactly match to the following are ignored.*/
86 static const char * const ignored_symbols[] = {
87 /*
88 * Symbols which vary between passes. Passes 1 and 2 must have
89 * identical symbol lists. The kallsyms_* symbols below are
90 * only added after pass 1, they would be included in pass 2
91 * when --all-symbols is specified so exclude them to get a
92 * stable symbol list.
93 */
94 "kallsyms_addresses",
95 "kallsyms_offsets",
96 "kallsyms_relative_base",
97 "kallsyms_num_syms",
98 "kallsyms_names",
99 "kallsyms_markers",
100 "kallsyms_token_table",
101 "kallsyms_token_index",
102 /* Exclude linker generated symbols which vary between passes */
103 "_SDA_BASE_", /* ppc */
104 "_SDA2_BASE_", /* ppc */
105 NULL
106 };
107
108 /* Symbol names that begin with the following are ignored.*/
109 static const char * const ignored_prefixes[] = {
110 "$", /* local symbols for ARM, MIPS, etc. */
111 ".LASANPC", /* s390 kasan local symbols */
112 "__crc_", /* modversions */
113 "__efistub_", /* arm64 EFI stub namespace */
114 "__kvm_nvhe_", /* arm64 non-VHE KVM namespace */
115 "__AArch64ADRPThunk_", /* arm64 lld */
116 "__ARMV5PILongThunk_", /* arm lld */
117 "__ARMV7PILongThunk_",
118 "__ThumbV7PILongThunk_",
119 "__LA25Thunk_", /* mips lld */
120 "__microLA25Thunk_",
121 NULL
122 };
123
124 /* Symbol names that end with the following are ignored.*/
125 static const char * const ignored_suffixes[] = {
126 "_from_arm", /* arm */
127 "_from_thumb", /* arm */
128 "_veneer", /* arm */
129 NULL
130 };
131
132 /* Symbol names that contain the following are ignored.*/
133 static const char * const ignored_matches[] = {
134 ".long_branch.", /* ppc stub */
135 ".plt_branch.", /* ppc stub */
136 NULL
137 };
138
139 const char * const *p;
140
141 for (p = ignored_symbols; *p; p++)
142 if (!strcmp(name, *p))
143 return true;
144
145 for (p = ignored_prefixes; *p; p++)
146 if (!strncmp(name, *p, strlen(*p)))
147 return true;
148
149 for (p = ignored_suffixes; *p; p++) {
150 int l = strlen(name) - strlen(*p);
151
152 if (l >= 0 && !strcmp(name + l, *p))
153 return true;
154 }
155
156 for (p = ignored_matches; *p; p++) {
157 if (strstr(name, *p))
158 return true;
159 }
160
161 if (type == 'U' || type == 'u')
162 return true;
163 /* exclude debugging symbols */
164 if (type == 'N' || type == 'n')
165 return true;
166
167 if (toupper(type) == 'A') {
168 /* Keep these useful absolute symbols */
169 if (strcmp(name, "__kernel_syscall_via_break") &&
170 strcmp(name, "__kernel_syscall_via_epc") &&
171 strcmp(name, "__kernel_sigtramp") &&
172 strcmp(name, "__gp"))
173 return true;
174 }
175
176 return false;
177}
178
179static void check_symbol_range(const char *sym, unsigned long long addr,
180 struct addr_range *ranges, int entries)
181{
182 size_t i;
183 struct addr_range *ar;
184
185 for (i = 0; i < entries; ++i) {
186 ar = &ranges[i];
187
188 if (strcmp(sym, ar->start_sym) == 0) {
189 ar->start = addr;
190 return;
191 } else if (strcmp(sym, ar->end_sym) == 0) {
192 ar->end = addr;
193 return;
194 }
195 }
196}
197
198static struct sym_entry *read_symbol(FILE *in)
199{
200 char name[500], type;
201 unsigned long long addr;
202 unsigned int len;
203 struct sym_entry *sym;
204 int rc;
205
206 rc = fscanf(in, "%llx %c %499s\n", &addr, &type, name);
207 if (rc != 3) {
208 if (rc != EOF && fgets(name, 500, in) == NULL)
209 fprintf(stderr, "Read error or end of file.\n");
210 return NULL;
211 }
212 if (strlen(name) >= KSYM_NAME_LEN) {
213 fprintf(stderr, "Symbol %s too long for kallsyms (%zu >= %d).\n"
214 "Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",
215 name, strlen(name), KSYM_NAME_LEN);
216 return NULL;
217 }
218
219 if (strcmp(name, "_text") == 0)
220 _text = addr;
221
222 /* Ignore most absolute/undefined (?) symbols. */
223 if (is_ignored_symbol(name, type))
224 return NULL;
225
226 check_symbol_range(name, addr, text_ranges, ARRAY_SIZE(text_ranges));
227 check_symbol_range(name, addr, &percpu_range, 1);
228
229 /* include the type field in the symbol name, so that it gets
230 * compressed together */
231
232 len = strlen(name) + 1;
233
234 sym = malloc(sizeof(*sym) + len + 1);
235 if (!sym) {
236 fprintf(stderr, "kallsyms failure: "
237 "unable to allocate required amount of memory\n");
238 exit(EXIT_FAILURE);
239 }
240 sym->addr = addr;
241 sym->len = len;
242 sym->sym[0] = type;
243 strcpy(sym_name(sym), name);
244 sym->percpu_absolute = 0;
245
246 return sym;
247}
248
249static int symbol_in_range(const struct sym_entry *s,
250 const struct addr_range *ranges, int entries)
251{
252 size_t i;
253 const struct addr_range *ar;
254
255 for (i = 0; i < entries; ++i) {
256 ar = &ranges[i];
257
258 if (s->addr >= ar->start && s->addr <= ar->end)
259 return 1;
260 }
261
262 return 0;
263}
264
265static int symbol_valid(const struct sym_entry *s)
266{
267 const char *name = sym_name(s);
268
269 /* if --all-symbols is not specified, then symbols outside the text
270 * and inittext sections are discarded */
271 if (!all_symbols) {
272 if (symbol_in_range(s, text_ranges,
273 ARRAY_SIZE(text_ranges)) == 0)
274 return 0;
275 /* Corner case. Discard any symbols with the same value as
276 * _etext _einittext; they can move between pass 1 and 2 when
277 * the kallsyms data are added. If these symbols move then
278 * they may get dropped in pass 2, which breaks the kallsyms
279 * rules.
280 */
281 if ((s->addr == text_range_text->end &&
282 strcmp(name, text_range_text->end_sym)) ||
283 (s->addr == text_range_inittext->end &&
284 strcmp(name, text_range_inittext->end_sym)))
285 return 0;
286 }
287
288 return 1;
289}
290
291/* remove all the invalid symbols from the table */
292static void shrink_table(void)
293{
294 unsigned int i, pos;
295
296 pos = 0;
297 for (i = 0; i < table_cnt; i++) {
298 if (symbol_valid(table[i])) {
299 if (pos != i)
300 table[pos] = table[i];
301 pos++;
302 } else {
303 free(table[i]);
304 }
305 }
306 table_cnt = pos;
307
308 /* When valid symbol is not registered, exit to error */
309 if (!table_cnt) {
310 fprintf(stderr, "No valid symbol.\n");
311 exit(1);
312 }
313}
314
315static void read_map(FILE *in)
316{
317 struct sym_entry *sym;
318
319 while (!feof(in)) {
320 sym = read_symbol(in);
321 if (!sym)
322 continue;
323
324 sym->start_pos = table_cnt;
325
326 if (table_cnt >= table_size) {
327 table_size += 10000;
328 table = realloc(table, sizeof(*table) * table_size);
329 if (!table) {
330 fprintf(stderr, "out of memory\n");
331 exit (1);
332 }
333 }
334
335 table[table_cnt++] = sym;
336 }
337}
338
339static void output_label(const char *label)
340{
341 printf(".globl %s\n", label);
342 printf("\tALGN\n");
343 printf("%s:\n", label);
344}
345
346/* Provide proper symbols relocatability by their '_text' relativeness. */
347static void output_address(unsigned long long addr)
348{
349 if (_text <= addr)
350 printf("\tPTR\t_text + %#llx\n", addr - _text);
351 else
352 printf("\tPTR\t_text - %#llx\n", _text - addr);
353}
354
355/* uncompress a compressed symbol. When this function is called, the best table
356 * might still be compressed itself, so the function needs to be recursive */
357static int expand_symbol(const unsigned char *data, int len, char *result)
358{
359 int c, rlen, total=0;
360
361 while (len) {
362 c = *data;
363 /* if the table holds a single char that is the same as the one
364 * we are looking for, then end the search */
365 if (best_table[c][0]==c && best_table_len[c]==1) {
366 *result++ = c;
367 total++;
368 } else {
369 /* if not, recurse and expand */
370 rlen = expand_symbol(best_table[c], best_table_len[c], result);
371 total += rlen;
372 result += rlen;
373 }
374 data++;
375 len--;
376 }
377 *result=0;
378
379 return total;
380}
381
382static int symbol_absolute(const struct sym_entry *s)
383{
384 return s->percpu_absolute;
385}
386
387static void write_src(void)
388{
389 unsigned int i, k, off;
390 unsigned int best_idx[256];
391 unsigned int *markers;
392 char buf[KSYM_NAME_LEN];
393
394 printf("#include <asm/bitsperlong.h>\n");
395 printf("#if BITS_PER_LONG == 64\n");
396 printf("#define PTR .quad\n");
397 printf("#define ALGN .balign 8\n");
398 printf("#else\n");
399 printf("#define PTR .long\n");
400 printf("#define ALGN .balign 4\n");
401 printf("#endif\n");
402
403 printf("\t.section .rodata, \"a\"\n");
404
405 if (!base_relative)
406 output_label("kallsyms_addresses");
407 else
408 output_label("kallsyms_offsets");
409
410 for (i = 0; i < table_cnt; i++) {
411 if (base_relative) {
412 /*
413 * Use the offset relative to the lowest value
414 * encountered of all relative symbols, and emit
415 * non-relocatable fixed offsets that will be fixed
416 * up at runtime.
417 */
418
419 long long offset;
420 int overflow;
421
422 if (!absolute_percpu) {
423 offset = table[i]->addr - relative_base;
424 overflow = (offset < 0 || offset > UINT_MAX);
425 } else if (symbol_absolute(table[i])) {
426 offset = table[i]->addr;
427 overflow = (offset < 0 || offset > INT_MAX);
428 } else {
429 offset = relative_base - table[i]->addr - 1;
430 overflow = (offset < INT_MIN || offset >= 0);
431 }
432 if (overflow) {
433 fprintf(stderr, "kallsyms failure: "
434 "%s symbol value %#llx out of range in relative mode\n",
435 symbol_absolute(table[i]) ? "absolute" : "relative",
436 table[i]->addr);
437 exit(EXIT_FAILURE);
438 }
439 printf("\t.long\t%#x\n", (int)offset);
440 } else if (!symbol_absolute(table[i])) {
441 output_address(table[i]->addr);
442 } else {
443 printf("\tPTR\t%#llx\n", table[i]->addr);
444 }
445 }
446 printf("\n");
447
448 if (base_relative) {
449 output_label("kallsyms_relative_base");
450 output_address(relative_base);
451 printf("\n");
452 }
453
454 output_label("kallsyms_num_syms");
455 printf("\t.long\t%u\n", table_cnt);
456 printf("\n");
457
458 /* table of offset markers, that give the offset in the compressed stream
459 * every 256 symbols */
460 markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
461 if (!markers) {
462 fprintf(stderr, "kallsyms failure: "
463 "unable to allocate required memory\n");
464 exit(EXIT_FAILURE);
465 }
466
467 output_label("kallsyms_names");
468 off = 0;
469 for (i = 0; i < table_cnt; i++) {
470 if ((i & 0xFF) == 0)
471 markers[i >> 8] = off;
472
473 printf("\t.byte 0x%02x", table[i]->len);
474 for (k = 0; k < table[i]->len; k++)
475 printf(", 0x%02x", table[i]->sym[k]);
476 printf("\n");
477
478 off += table[i]->len + 1;
479 }
480 printf("\n");
481
482 output_label("kallsyms_markers");
483 for (i = 0; i < ((table_cnt + 255) >> 8); i++)
484 printf("\t.long\t%u\n", markers[i]);
485 printf("\n");
486
487 free(markers);
488
489 output_label("kallsyms_token_table");
490 off = 0;
491 for (i = 0; i < 256; i++) {
492 best_idx[i] = off;
493 expand_symbol(best_table[i], best_table_len[i], buf);
494 printf("\t.asciz\t\"%s\"\n", buf);
495 off += strlen(buf) + 1;
496 }
497 printf("\n");
498
499 output_label("kallsyms_token_index");
500 for (i = 0; i < 256; i++)
501 printf("\t.short\t%d\n", best_idx[i]);
502 printf("\n");
503}
504
505
506/* table lookup compression functions */
507
508/* count all the possible tokens in a symbol */
509static void learn_symbol(const unsigned char *symbol, int len)
510{
511 int i;
512
513 for (i = 0; i < len - 1; i++)
514 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
515}
516
517/* decrease the count for all the possible tokens in a symbol */
518static void forget_symbol(const unsigned char *symbol, int len)
519{
520 int i;
521
522 for (i = 0; i < len - 1; i++)
523 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
524}
525
526/* do the initial token count */
527static void build_initial_tok_table(void)
528{
529 unsigned int i;
530
531 for (i = 0; i < table_cnt; i++)
532 learn_symbol(table[i]->sym, table[i]->len);
533}
534
535static unsigned char *find_token(unsigned char *str, int len,
536 const unsigned char *token)
537{
538 int i;
539
540 for (i = 0; i < len - 1; i++) {
541 if (str[i] == token[0] && str[i+1] == token[1])
542 return &str[i];
543 }
544 return NULL;
545}
546
547/* replace a given token in all the valid symbols. Use the sampled symbols
548 * to update the counts */
549static void compress_symbols(const unsigned char *str, int idx)
550{
551 unsigned int i, len, size;
552 unsigned char *p1, *p2;
553
554 for (i = 0; i < table_cnt; i++) {
555
556 len = table[i]->len;
557 p1 = table[i]->sym;
558
559 /* find the token on the symbol */
560 p2 = find_token(p1, len, str);
561 if (!p2) continue;
562
563 /* decrease the counts for this symbol's tokens */
564 forget_symbol(table[i]->sym, len);
565
566 size = len;
567
568 do {
569 *p2 = idx;
570 p2++;
571 size -= (p2 - p1);
572 memmove(p2, p2 + 1, size);
573 p1 = p2;
574 len--;
575
576 if (size < 2) break;
577
578 /* find the token on the symbol */
579 p2 = find_token(p1, size, str);
580
581 } while (p2);
582
583 table[i]->len = len;
584
585 /* increase the counts for this symbol's new tokens */
586 learn_symbol(table[i]->sym, len);
587 }
588}
589
590/* search the token with the maximum profit */
591static int find_best_token(void)
592{
593 int i, best, bestprofit;
594
595 bestprofit=-10000;
596 best = 0;
597
598 for (i = 0; i < 0x10000; i++) {
599 if (token_profit[i] > bestprofit) {
600 best = i;
601 bestprofit = token_profit[i];
602 }
603 }
604 return best;
605}
606
607/* this is the core of the algorithm: calculate the "best" table */
608static void optimize_result(void)
609{
610 int i, best;
611
612 /* using the '\0' symbol last allows compress_symbols to use standard
613 * fast string functions */
614 for (i = 255; i >= 0; i--) {
615
616 /* if this table slot is empty (it is not used by an actual
617 * original char code */
618 if (!best_table_len[i]) {
619
620 /* find the token with the best profit value */
621 best = find_best_token();
622 if (token_profit[best] == 0)
623 break;
624
625 /* place it in the "best" table */
626 best_table_len[i] = 2;
627 best_table[i][0] = best & 0xFF;
628 best_table[i][1] = (best >> 8) & 0xFF;
629
630 /* replace this token in all the valid symbols */
631 compress_symbols(best_table[i], i);
632 }
633 }
634}
635
636/* start by placing the symbols that are actually used on the table */
637static void insert_real_symbols_in_table(void)
638{
639 unsigned int i, j, c;
640
641 for (i = 0; i < table_cnt; i++) {
642 for (j = 0; j < table[i]->len; j++) {
643 c = table[i]->sym[j];
644 best_table[c][0]=c;
645 best_table_len[c]=1;
646 }
647 }
648}
649
650static void optimize_token_table(void)
651{
652 build_initial_tok_table();
653
654 insert_real_symbols_in_table();
655
656 optimize_result();
657}
658
659/* guess for "linker script provide" symbol */
660static int may_be_linker_script_provide_symbol(const struct sym_entry *se)
661{
662 const char *symbol = sym_name(se);
663 int len = se->len - 1;
664
665 if (len < 8)
666 return 0;
667
668 if (symbol[0] != '_' || symbol[1] != '_')
669 return 0;
670
671 /* __start_XXXXX */
672 if (!memcmp(symbol + 2, "start_", 6))
673 return 1;
674
675 /* __stop_XXXXX */
676 if (!memcmp(symbol + 2, "stop_", 5))
677 return 1;
678
679 /* __end_XXXXX */
680 if (!memcmp(symbol + 2, "end_", 4))
681 return 1;
682
683 /* __XXXXX_start */
684 if (!memcmp(symbol + len - 6, "_start", 6))
685 return 1;
686
687 /* __XXXXX_end */
688 if (!memcmp(symbol + len - 4, "_end", 4))
689 return 1;
690
691 return 0;
692}
693
694static int compare_symbols(const void *a, const void *b)
695{
696 const struct sym_entry *sa = *(const struct sym_entry **)a;
697 const struct sym_entry *sb = *(const struct sym_entry **)b;
698 int wa, wb;
699
700 /* sort by address first */
701 if (sa->addr > sb->addr)
702 return 1;
703 if (sa->addr < sb->addr)
704 return -1;
705
706 /* sort by "weakness" type */
707 wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
708 wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
709 if (wa != wb)
710 return wa - wb;
711
712 /* sort by "linker script provide" type */
713 wa = may_be_linker_script_provide_symbol(sa);
714 wb = may_be_linker_script_provide_symbol(sb);
715 if (wa != wb)
716 return wa - wb;
717
718 /* sort by the number of prefix underscores */
719 wa = strspn(sym_name(sa), "_");
720 wb = strspn(sym_name(sb), "_");
721 if (wa != wb)
722 return wa - wb;
723
724 /* sort by initial order, so that other symbols are left undisturbed */
725 return sa->start_pos - sb->start_pos;
726}
727
728static void sort_symbols(void)
729{
730 qsort(table, table_cnt, sizeof(table[0]), compare_symbols);
731}
732
733static void make_percpus_absolute(void)
734{
735 unsigned int i;
736
737 for (i = 0; i < table_cnt; i++)
738 if (symbol_in_range(table[i], &percpu_range, 1)) {
739 /*
740 * Keep the 'A' override for percpu symbols to
741 * ensure consistent behavior compared to older
742 * versions of this tool.
743 */
744 table[i]->sym[0] = 'A';
745 table[i]->percpu_absolute = 1;
746 }
747}
748
749/* find the minimum non-absolute symbol address */
750static void record_relative_base(void)
751{
752 unsigned int i;
753
754 for (i = 0; i < table_cnt; i++)
755 if (!symbol_absolute(table[i])) {
756 /*
757 * The table is sorted by address.
758 * Take the first non-absolute symbol value.
759 */
760 relative_base = table[i]->addr;
761 return;
762 }
763}
764
765int main(int argc, char **argv)
766{
767 if (argc >= 2) {
768 int i;
769 for (i = 1; i < argc; i++) {
770 if(strcmp(argv[i], "--all-symbols") == 0)
771 all_symbols = 1;
772 else if (strcmp(argv[i], "--absolute-percpu") == 0)
773 absolute_percpu = 1;
774 else if (strcmp(argv[i], "--base-relative") == 0)
775 base_relative = 1;
776 else
777 usage();
778 }
779 } else if (argc != 1)
780 usage();
781
782 read_map(stdin);
783 shrink_table();
784 if (absolute_percpu)
785 make_percpus_absolute();
786 sort_symbols();
787 if (base_relative)
788 record_relative_base();
789 optimize_token_table();
790 write_src();
791
792 return 0;
793}