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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 addr_range {
40 const char *start_sym, *end_sym;
41 unsigned long long start, end;
42};
43
44static unsigned long long _text;
45static struct addr_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 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 = 0;
61static int absolute_percpu = 0;
62static char symbol_prefix_char = '\0';
63static unsigned long long kernel_start_addr = 0;
64
65int token_profit[0x10000];
66
67/* the table that holds the result of the compression */
68unsigned char best_table[256][2];
69unsigned char best_table_len[256];
70
71
72static void usage(void)
73{
74 fprintf(stderr, "Usage: kallsyms [--all-symbols] "
75 "[--symbol-prefix=<prefix char>] "
76 "[--page-offset=<CONFIG_PAGE_OFFSET>] "
77 "< in.map > out.S\n");
78 exit(1);
79}
80
81/*
82 * This ignores the intensely annoying "mapping symbols" found
83 * in ARM ELF files: $a, $t and $d.
84 */
85static inline int is_arm_mapping_symbol(const char *str)
86{
87 return str[0] == '$' && strchr("atd", str[1])
88 && (str[2] == '\0' || str[2] == '.');
89}
90
91static int check_symbol_range(const char *sym, unsigned long long addr,
92 struct addr_range *ranges, int entries)
93{
94 size_t i;
95 struct addr_range *ar;
96
97 for (i = 0; i < entries; ++i) {
98 ar = &ranges[i];
99
100 if (strcmp(sym, ar->start_sym) == 0) {
101 ar->start = addr;
102 return 0;
103 } else if (strcmp(sym, ar->end_sym) == 0) {
104 ar->end = addr;
105 return 0;
106 }
107 }
108
109 return 1;
110}
111
112static int read_symbol(FILE *in, struct sym_entry *s)
113{
114 char str[500];
115 char *sym, stype;
116 int rc;
117
118 rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str);
119 if (rc != 3) {
120 if (rc != EOF && fgets(str, 500, in) == NULL)
121 fprintf(stderr, "Read error or end of file.\n");
122 return -1;
123 }
124 if (strlen(str) > KSYM_NAME_LEN) {
125 fprintf(stderr, "Symbol %s too long for kallsyms (%zu vs %d).\n"
126 "Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",
127 str, strlen(str), KSYM_NAME_LEN);
128 return -1;
129 }
130
131 sym = str;
132 /* skip prefix char */
133 if (symbol_prefix_char && str[0] == symbol_prefix_char)
134 sym++;
135
136 /* Ignore most absolute/undefined (?) symbols. */
137 if (strcmp(sym, "_text") == 0)
138 _text = s->addr;
139 else if (check_symbol_range(sym, s->addr, text_ranges,
140 ARRAY_SIZE(text_ranges)) == 0)
141 /* nothing to do */;
142 else if (toupper(stype) == 'A')
143 {
144 /* Keep these useful absolute symbols */
145 if (strcmp(sym, "__kernel_syscall_via_break") &&
146 strcmp(sym, "__kernel_syscall_via_epc") &&
147 strcmp(sym, "__kernel_sigtramp") &&
148 strcmp(sym, "__gp"))
149 return -1;
150
151 }
152 else if (toupper(stype) == 'U' ||
153 is_arm_mapping_symbol(sym))
154 return -1;
155 /* exclude also MIPS ELF local symbols ($L123 instead of .L123) */
156 else if (str[0] == '$')
157 return -1;
158 /* exclude debugging symbols */
159 else if (stype == 'N')
160 return -1;
161
162 /* include the type field in the symbol name, so that it gets
163 * compressed together */
164 s->len = strlen(str) + 1;
165 s->sym = malloc(s->len + 1);
166 if (!s->sym) {
167 fprintf(stderr, "kallsyms failure: "
168 "unable to allocate required amount of memory\n");
169 exit(EXIT_FAILURE);
170 }
171 strcpy((char *)s->sym + 1, str);
172 s->sym[0] = stype;
173
174 /* Record if we've found __per_cpu_start/end. */
175 check_symbol_range(sym, s->addr, &percpu_range, 1);
176
177 return 0;
178}
179
180static int symbol_in_range(struct sym_entry *s, struct addr_range *ranges,
181 int entries)
182{
183 size_t i;
184 struct addr_range *ar;
185
186 for (i = 0; i < entries; ++i) {
187 ar = &ranges[i];
188
189 if (s->addr >= ar->start && s->addr <= ar->end)
190 return 1;
191 }
192
193 return 0;
194}
195
196static int symbol_valid(struct sym_entry *s)
197{
198 /* Symbols which vary between passes. Passes 1 and 2 must have
199 * identical symbol lists. The kallsyms_* symbols below are only added
200 * after pass 1, they would be included in pass 2 when --all-symbols is
201 * specified so exclude them to get a stable symbol list.
202 */
203 static char *special_symbols[] = {
204 "kallsyms_addresses",
205 "kallsyms_num_syms",
206 "kallsyms_names",
207 "kallsyms_markers",
208 "kallsyms_token_table",
209 "kallsyms_token_index",
210
211 /* Exclude linker generated symbols which vary between passes */
212 "_SDA_BASE_", /* ppc */
213 "_SDA2_BASE_", /* ppc */
214 NULL };
215 int i;
216 int offset = 1;
217
218 if (s->addr < kernel_start_addr)
219 return 0;
220
221 /* skip prefix char */
222 if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char)
223 offset++;
224
225 /* if --all-symbols is not specified, then symbols outside the text
226 * and inittext sections are discarded */
227 if (!all_symbols) {
228 if (symbol_in_range(s, text_ranges,
229 ARRAY_SIZE(text_ranges)) == 0)
230 return 0;
231 /* Corner case. Discard any symbols with the same value as
232 * _etext _einittext; they can move between pass 1 and 2 when
233 * the kallsyms data are added. If these symbols move then
234 * they may get dropped in pass 2, which breaks the kallsyms
235 * rules.
236 */
237 if ((s->addr == text_range_text->end &&
238 strcmp((char *)s->sym + offset,
239 text_range_text->end_sym)) ||
240 (s->addr == text_range_inittext->end &&
241 strcmp((char *)s->sym + offset,
242 text_range_inittext->end_sym)))
243 return 0;
244 }
245
246 /* Exclude symbols which vary between passes. */
247 if (strstr((char *)s->sym + offset, "_compiled."))
248 return 0;
249
250 for (i = 0; special_symbols[i]; i++)
251 if( strcmp((char *)s->sym + offset, special_symbols[i]) == 0 )
252 return 0;
253
254 return 1;
255}
256
257static void read_map(FILE *in)
258{
259 while (!feof(in)) {
260 if (table_cnt >= table_size) {
261 table_size += 10000;
262 table = realloc(table, sizeof(*table) * table_size);
263 if (!table) {
264 fprintf(stderr, "out of memory\n");
265 exit (1);
266 }
267 }
268 if (read_symbol(in, &table[table_cnt]) == 0) {
269 table[table_cnt].start_pos = table_cnt;
270 table_cnt++;
271 }
272 }
273}
274
275static void output_label(char *label)
276{
277 if (symbol_prefix_char)
278 printf(".globl %c%s\n", symbol_prefix_char, label);
279 else
280 printf(".globl %s\n", label);
281 printf("\tALGN\n");
282 if (symbol_prefix_char)
283 printf("%c%s:\n", symbol_prefix_char, label);
284 else
285 printf("%s:\n", label);
286}
287
288/* uncompress a compressed symbol. When this function is called, the best table
289 * might still be compressed itself, so the function needs to be recursive */
290static int expand_symbol(unsigned char *data, int len, char *result)
291{
292 int c, rlen, total=0;
293
294 while (len) {
295 c = *data;
296 /* if the table holds a single char that is the same as the one
297 * we are looking for, then end the search */
298 if (best_table[c][0]==c && best_table_len[c]==1) {
299 *result++ = c;
300 total++;
301 } else {
302 /* if not, recurse and expand */
303 rlen = expand_symbol(best_table[c], best_table_len[c], result);
304 total += rlen;
305 result += rlen;
306 }
307 data++;
308 len--;
309 }
310 *result=0;
311
312 return total;
313}
314
315static int symbol_absolute(struct sym_entry *s)
316{
317 return toupper(s->sym[0]) == 'A';
318}
319
320static void write_src(void)
321{
322 unsigned int i, k, off;
323 unsigned int best_idx[256];
324 unsigned int *markers;
325 char buf[KSYM_NAME_LEN];
326
327 printf("#include <asm/types.h>\n");
328 printf("#if BITS_PER_LONG == 64\n");
329 printf("#define PTR .quad\n");
330 printf("#define ALGN .align 8\n");
331 printf("#else\n");
332 printf("#define PTR .long\n");
333 printf("#define ALGN .align 4\n");
334 printf("#endif\n");
335
336 printf("\t.section .rodata, \"a\"\n");
337
338 /* Provide proper symbols relocatability by their '_text'
339 * relativeness. The symbol names cannot be used to construct
340 * normal symbol references as the list of symbols contains
341 * symbols that are declared static and are private to their
342 * .o files. This prevents .tmp_kallsyms.o or any other
343 * object from referencing them.
344 */
345 output_label("kallsyms_addresses");
346 for (i = 0; i < table_cnt; i++) {
347 if (!symbol_absolute(&table[i])) {
348 if (_text <= table[i].addr)
349 printf("\tPTR\t_text + %#llx\n",
350 table[i].addr - _text);
351 else
352 printf("\tPTR\t_text - %#llx\n",
353 _text - table[i].addr);
354 } else {
355 printf("\tPTR\t%#llx\n", table[i].addr);
356 }
357 }
358 printf("\n");
359
360 output_label("kallsyms_num_syms");
361 printf("\tPTR\t%d\n", table_cnt);
362 printf("\n");
363
364 /* table of offset markers, that give the offset in the compressed stream
365 * every 256 symbols */
366 markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
367 if (!markers) {
368 fprintf(stderr, "kallsyms failure: "
369 "unable to allocate required memory\n");
370 exit(EXIT_FAILURE);
371 }
372
373 output_label("kallsyms_names");
374 off = 0;
375 for (i = 0; i < table_cnt; i++) {
376 if ((i & 0xFF) == 0)
377 markers[i >> 8] = off;
378
379 printf("\t.byte 0x%02x", table[i].len);
380 for (k = 0; k < table[i].len; k++)
381 printf(", 0x%02x", table[i].sym[k]);
382 printf("\n");
383
384 off += table[i].len + 1;
385 }
386 printf("\n");
387
388 output_label("kallsyms_markers");
389 for (i = 0; i < ((table_cnt + 255) >> 8); i++)
390 printf("\tPTR\t%d\n", markers[i]);
391 printf("\n");
392
393 free(markers);
394
395 output_label("kallsyms_token_table");
396 off = 0;
397 for (i = 0; i < 256; i++) {
398 best_idx[i] = off;
399 expand_symbol(best_table[i], best_table_len[i], buf);
400 printf("\t.asciz\t\"%s\"\n", buf);
401 off += strlen(buf) + 1;
402 }
403 printf("\n");
404
405 output_label("kallsyms_token_index");
406 for (i = 0; i < 256; i++)
407 printf("\t.short\t%d\n", best_idx[i]);
408 printf("\n");
409}
410
411
412/* table lookup compression functions */
413
414/* count all the possible tokens in a symbol */
415static void learn_symbol(unsigned char *symbol, int len)
416{
417 int i;
418
419 for (i = 0; i < len - 1; i++)
420 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
421}
422
423/* decrease the count for all the possible tokens in a symbol */
424static void forget_symbol(unsigned char *symbol, int len)
425{
426 int i;
427
428 for (i = 0; i < len - 1; i++)
429 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
430}
431
432/* remove all the invalid symbols from the table and do the initial token count */
433static void build_initial_tok_table(void)
434{
435 unsigned int i, pos;
436
437 pos = 0;
438 for (i = 0; i < table_cnt; i++) {
439 if ( symbol_valid(&table[i]) ) {
440 if (pos != i)
441 table[pos] = table[i];
442 learn_symbol(table[pos].sym, table[pos].len);
443 pos++;
444 }
445 }
446 table_cnt = pos;
447}
448
449static void *find_token(unsigned char *str, int len, unsigned char *token)
450{
451 int i;
452
453 for (i = 0; i < len - 1; i++) {
454 if (str[i] == token[0] && str[i+1] == token[1])
455 return &str[i];
456 }
457 return NULL;
458}
459
460/* replace a given token in all the valid symbols. Use the sampled symbols
461 * to update the counts */
462static void compress_symbols(unsigned char *str, int idx)
463{
464 unsigned int i, len, size;
465 unsigned char *p1, *p2;
466
467 for (i = 0; i < table_cnt; i++) {
468
469 len = table[i].len;
470 p1 = table[i].sym;
471
472 /* find the token on the symbol */
473 p2 = find_token(p1, len, str);
474 if (!p2) continue;
475
476 /* decrease the counts for this symbol's tokens */
477 forget_symbol(table[i].sym, len);
478
479 size = len;
480
481 do {
482 *p2 = idx;
483 p2++;
484 size -= (p2 - p1);
485 memmove(p2, p2 + 1, size);
486 p1 = p2;
487 len--;
488
489 if (size < 2) break;
490
491 /* find the token on the symbol */
492 p2 = find_token(p1, size, str);
493
494 } while (p2);
495
496 table[i].len = len;
497
498 /* increase the counts for this symbol's new tokens */
499 learn_symbol(table[i].sym, len);
500 }
501}
502
503/* search the token with the maximum profit */
504static int find_best_token(void)
505{
506 int i, best, bestprofit;
507
508 bestprofit=-10000;
509 best = 0;
510
511 for (i = 0; i < 0x10000; i++) {
512 if (token_profit[i] > bestprofit) {
513 best = i;
514 bestprofit = token_profit[i];
515 }
516 }
517 return best;
518}
519
520/* this is the core of the algorithm: calculate the "best" table */
521static void optimize_result(void)
522{
523 int i, best;
524
525 /* using the '\0' symbol last allows compress_symbols to use standard
526 * fast string functions */
527 for (i = 255; i >= 0; i--) {
528
529 /* if this table slot is empty (it is not used by an actual
530 * original char code */
531 if (!best_table_len[i]) {
532
533 /* find the token with the breates profit value */
534 best = find_best_token();
535 if (token_profit[best] == 0)
536 break;
537
538 /* place it in the "best" table */
539 best_table_len[i] = 2;
540 best_table[i][0] = best & 0xFF;
541 best_table[i][1] = (best >> 8) & 0xFF;
542
543 /* replace this token in all the valid symbols */
544 compress_symbols(best_table[i], i);
545 }
546 }
547}
548
549/* start by placing the symbols that are actually used on the table */
550static void insert_real_symbols_in_table(void)
551{
552 unsigned int i, j, c;
553
554 memset(best_table, 0, sizeof(best_table));
555 memset(best_table_len, 0, sizeof(best_table_len));
556
557 for (i = 0; i < table_cnt; i++) {
558 for (j = 0; j < table[i].len; j++) {
559 c = table[i].sym[j];
560 best_table[c][0]=c;
561 best_table_len[c]=1;
562 }
563 }
564}
565
566static void optimize_token_table(void)
567{
568 build_initial_tok_table();
569
570 insert_real_symbols_in_table();
571
572 /* When valid symbol is not registered, exit to error */
573 if (!table_cnt) {
574 fprintf(stderr, "No valid symbol.\n");
575 exit(1);
576 }
577
578 optimize_result();
579}
580
581/* guess for "linker script provide" symbol */
582static int may_be_linker_script_provide_symbol(const struct sym_entry *se)
583{
584 const char *symbol = (char *)se->sym + 1;
585 int len = se->len - 1;
586
587 if (len < 8)
588 return 0;
589
590 if (symbol[0] != '_' || symbol[1] != '_')
591 return 0;
592
593 /* __start_XXXXX */
594 if (!memcmp(symbol + 2, "start_", 6))
595 return 1;
596
597 /* __stop_XXXXX */
598 if (!memcmp(symbol + 2, "stop_", 5))
599 return 1;
600
601 /* __end_XXXXX */
602 if (!memcmp(symbol + 2, "end_", 4))
603 return 1;
604
605 /* __XXXXX_start */
606 if (!memcmp(symbol + len - 6, "_start", 6))
607 return 1;
608
609 /* __XXXXX_end */
610 if (!memcmp(symbol + len - 4, "_end", 4))
611 return 1;
612
613 return 0;
614}
615
616static int prefix_underscores_count(const char *str)
617{
618 const char *tail = str;
619
620 while (*tail == '_')
621 tail++;
622
623 return tail - str;
624}
625
626static int compare_symbols(const void *a, const void *b)
627{
628 const struct sym_entry *sa;
629 const struct sym_entry *sb;
630 int wa, wb;
631
632 sa = a;
633 sb = b;
634
635 /* sort by address first */
636 if (sa->addr > sb->addr)
637 return 1;
638 if (sa->addr < sb->addr)
639 return -1;
640
641 /* sort by "weakness" type */
642 wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
643 wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
644 if (wa != wb)
645 return wa - wb;
646
647 /* sort by "linker script provide" type */
648 wa = may_be_linker_script_provide_symbol(sa);
649 wb = may_be_linker_script_provide_symbol(sb);
650 if (wa != wb)
651 return wa - wb;
652
653 /* sort by the number of prefix underscores */
654 wa = prefix_underscores_count((const char *)sa->sym + 1);
655 wb = prefix_underscores_count((const char *)sb->sym + 1);
656 if (wa != wb)
657 return wa - wb;
658
659 /* sort by initial order, so that other symbols are left undisturbed */
660 return sa->start_pos - sb->start_pos;
661}
662
663static void sort_symbols(void)
664{
665 qsort(table, table_cnt, sizeof(struct sym_entry), compare_symbols);
666}
667
668static void make_percpus_absolute(void)
669{
670 unsigned int i;
671
672 for (i = 0; i < table_cnt; i++)
673 if (symbol_in_range(&table[i], &percpu_range, 1))
674 table[i].sym[0] = 'A';
675}
676
677int main(int argc, char **argv)
678{
679 if (argc >= 2) {
680 int i;
681 for (i = 1; i < argc; i++) {
682 if(strcmp(argv[i], "--all-symbols") == 0)
683 all_symbols = 1;
684 else if (strcmp(argv[i], "--absolute-percpu") == 0)
685 absolute_percpu = 1;
686 else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) {
687 char *p = &argv[i][16];
688 /* skip quote */
689 if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
690 p++;
691 symbol_prefix_char = *p;
692 } else if (strncmp(argv[i], "--page-offset=", 14) == 0) {
693 const char *p = &argv[i][14];
694 kernel_start_addr = strtoull(p, NULL, 16);
695 } else
696 usage();
697 }
698 } else if (argc != 1)
699 usage();
700
701 read_map(stdin);
702 if (absolute_percpu)
703 make_percpus_absolute();
704 sort_symbols();
705 optimize_token_table();
706 write_src();
707
708 return 0;
709}
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 NULL
116 };
117
118 /* Symbol names that end with the following are ignored.*/
119 static const char * const ignored_suffixes[] = {
120 "_from_arm", /* arm */
121 "_from_thumb", /* arm */
122 "_veneer", /* arm */
123 NULL
124 };
125
126 /* Symbol names that contain the following are ignored.*/
127 static const char * const ignored_matches[] = {
128 ".long_branch.", /* ppc stub */
129 ".plt_branch.", /* ppc stub */
130 NULL
131 };
132
133 const char * const *p;
134
135 for (p = ignored_symbols; *p; p++)
136 if (!strcmp(name, *p))
137 return true;
138
139 for (p = ignored_prefixes; *p; p++)
140 if (!strncmp(name, *p, strlen(*p)))
141 return true;
142
143 for (p = ignored_suffixes; *p; p++) {
144 int l = strlen(name) - strlen(*p);
145
146 if (l >= 0 && !strcmp(name + l, *p))
147 return true;
148 }
149
150 for (p = ignored_matches; *p; p++) {
151 if (strstr(name, *p))
152 return true;
153 }
154
155 if (type == 'U' || type == 'u')
156 return true;
157 /* exclude debugging symbols */
158 if (type == 'N' || type == 'n')
159 return true;
160
161 if (toupper(type) == 'A') {
162 /* Keep these useful absolute symbols */
163 if (strcmp(name, "__kernel_syscall_via_break") &&
164 strcmp(name, "__kernel_syscall_via_epc") &&
165 strcmp(name, "__kernel_sigtramp") &&
166 strcmp(name, "__gp"))
167 return true;
168 }
169
170 return false;
171}
172
173static void check_symbol_range(const char *sym, unsigned long long addr,
174 struct addr_range *ranges, int entries)
175{
176 size_t i;
177 struct addr_range *ar;
178
179 for (i = 0; i < entries; ++i) {
180 ar = &ranges[i];
181
182 if (strcmp(sym, ar->start_sym) == 0) {
183 ar->start = addr;
184 return;
185 } else if (strcmp(sym, ar->end_sym) == 0) {
186 ar->end = addr;
187 return;
188 }
189 }
190}
191
192static struct sym_entry *read_symbol(FILE *in)
193{
194 char name[500], type;
195 unsigned long long addr;
196 unsigned int len;
197 struct sym_entry *sym;
198 int rc;
199
200 rc = fscanf(in, "%llx %c %499s\n", &addr, &type, name);
201 if (rc != 3) {
202 if (rc != EOF && fgets(name, 500, in) == NULL)
203 fprintf(stderr, "Read error or end of file.\n");
204 return NULL;
205 }
206 if (strlen(name) >= KSYM_NAME_LEN) {
207 fprintf(stderr, "Symbol %s too long for kallsyms (%zu >= %d).\n"
208 "Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",
209 name, strlen(name), KSYM_NAME_LEN);
210 return NULL;
211 }
212
213 if (strcmp(name, "_text") == 0)
214 _text = addr;
215
216 /* Ignore most absolute/undefined (?) symbols. */
217 if (is_ignored_symbol(name, type))
218 return NULL;
219
220 check_symbol_range(name, addr, text_ranges, ARRAY_SIZE(text_ranges));
221 check_symbol_range(name, addr, &percpu_range, 1);
222
223 /* include the type field in the symbol name, so that it gets
224 * compressed together */
225
226 len = strlen(name) + 1;
227
228 sym = malloc(sizeof(*sym) + len + 1);
229 if (!sym) {
230 fprintf(stderr, "kallsyms failure: "
231 "unable to allocate required amount of memory\n");
232 exit(EXIT_FAILURE);
233 }
234 sym->addr = addr;
235 sym->len = len;
236 sym->sym[0] = type;
237 strcpy(sym_name(sym), name);
238 sym->percpu_absolute = 0;
239
240 return sym;
241}
242
243static int symbol_in_range(const struct sym_entry *s,
244 const struct addr_range *ranges, int entries)
245{
246 size_t i;
247 const struct addr_range *ar;
248
249 for (i = 0; i < entries; ++i) {
250 ar = &ranges[i];
251
252 if (s->addr >= ar->start && s->addr <= ar->end)
253 return 1;
254 }
255
256 return 0;
257}
258
259static int symbol_valid(const struct sym_entry *s)
260{
261 const char *name = sym_name(s);
262
263 /* if --all-symbols is not specified, then symbols outside the text
264 * and inittext sections are discarded */
265 if (!all_symbols) {
266 if (symbol_in_range(s, text_ranges,
267 ARRAY_SIZE(text_ranges)) == 0)
268 return 0;
269 /* Corner case. Discard any symbols with the same value as
270 * _etext _einittext; they can move between pass 1 and 2 when
271 * the kallsyms data are added. If these symbols move then
272 * they may get dropped in pass 2, which breaks the kallsyms
273 * rules.
274 */
275 if ((s->addr == text_range_text->end &&
276 strcmp(name, text_range_text->end_sym)) ||
277 (s->addr == text_range_inittext->end &&
278 strcmp(name, text_range_inittext->end_sym)))
279 return 0;
280 }
281
282 return 1;
283}
284
285/* remove all the invalid symbols from the table */
286static void shrink_table(void)
287{
288 unsigned int i, pos;
289
290 pos = 0;
291 for (i = 0; i < table_cnt; i++) {
292 if (symbol_valid(table[i])) {
293 if (pos != i)
294 table[pos] = table[i];
295 pos++;
296 } else {
297 free(table[i]);
298 }
299 }
300 table_cnt = pos;
301
302 /* When valid symbol is not registered, exit to error */
303 if (!table_cnt) {
304 fprintf(stderr, "No valid symbol.\n");
305 exit(1);
306 }
307}
308
309static void read_map(FILE *in)
310{
311 struct sym_entry *sym;
312
313 while (!feof(in)) {
314 sym = read_symbol(in);
315 if (!sym)
316 continue;
317
318 sym->start_pos = table_cnt;
319
320 if (table_cnt >= table_size) {
321 table_size += 10000;
322 table = realloc(table, sizeof(*table) * table_size);
323 if (!table) {
324 fprintf(stderr, "out of memory\n");
325 exit (1);
326 }
327 }
328
329 table[table_cnt++] = sym;
330 }
331}
332
333static void output_label(const char *label)
334{
335 printf(".globl %s\n", label);
336 printf("\tALGN\n");
337 printf("%s:\n", label);
338}
339
340/* Provide proper symbols relocatability by their '_text' relativeness. */
341static void output_address(unsigned long long addr)
342{
343 if (_text <= addr)
344 printf("\tPTR\t_text + %#llx\n", addr - _text);
345 else
346 printf("\tPTR\t_text - %#llx\n", _text - addr);
347}
348
349/* uncompress a compressed symbol. When this function is called, the best table
350 * might still be compressed itself, so the function needs to be recursive */
351static int expand_symbol(const unsigned char *data, int len, char *result)
352{
353 int c, rlen, total=0;
354
355 while (len) {
356 c = *data;
357 /* if the table holds a single char that is the same as the one
358 * we are looking for, then end the search */
359 if (best_table[c][0]==c && best_table_len[c]==1) {
360 *result++ = c;
361 total++;
362 } else {
363 /* if not, recurse and expand */
364 rlen = expand_symbol(best_table[c], best_table_len[c], result);
365 total += rlen;
366 result += rlen;
367 }
368 data++;
369 len--;
370 }
371 *result=0;
372
373 return total;
374}
375
376static int symbol_absolute(const struct sym_entry *s)
377{
378 return s->percpu_absolute;
379}
380
381static void write_src(void)
382{
383 unsigned int i, k, off;
384 unsigned int best_idx[256];
385 unsigned int *markers;
386 char buf[KSYM_NAME_LEN];
387
388 printf("#include <asm/bitsperlong.h>\n");
389 printf("#if BITS_PER_LONG == 64\n");
390 printf("#define PTR .quad\n");
391 printf("#define ALGN .balign 8\n");
392 printf("#else\n");
393 printf("#define PTR .long\n");
394 printf("#define ALGN .balign 4\n");
395 printf("#endif\n");
396
397 printf("\t.section .rodata, \"a\"\n");
398
399 if (!base_relative)
400 output_label("kallsyms_addresses");
401 else
402 output_label("kallsyms_offsets");
403
404 for (i = 0; i < table_cnt; i++) {
405 if (base_relative) {
406 /*
407 * Use the offset relative to the lowest value
408 * encountered of all relative symbols, and emit
409 * non-relocatable fixed offsets that will be fixed
410 * up at runtime.
411 */
412
413 long long offset;
414 int overflow;
415
416 if (!absolute_percpu) {
417 offset = table[i]->addr - relative_base;
418 overflow = (offset < 0 || offset > UINT_MAX);
419 } else if (symbol_absolute(table[i])) {
420 offset = table[i]->addr;
421 overflow = (offset < 0 || offset > INT_MAX);
422 } else {
423 offset = relative_base - table[i]->addr - 1;
424 overflow = (offset < INT_MIN || offset >= 0);
425 }
426 if (overflow) {
427 fprintf(stderr, "kallsyms failure: "
428 "%s symbol value %#llx out of range in relative mode\n",
429 symbol_absolute(table[i]) ? "absolute" : "relative",
430 table[i]->addr);
431 exit(EXIT_FAILURE);
432 }
433 printf("\t.long\t%#x\n", (int)offset);
434 } else if (!symbol_absolute(table[i])) {
435 output_address(table[i]->addr);
436 } else {
437 printf("\tPTR\t%#llx\n", table[i]->addr);
438 }
439 }
440 printf("\n");
441
442 if (base_relative) {
443 output_label("kallsyms_relative_base");
444 output_address(relative_base);
445 printf("\n");
446 }
447
448 output_label("kallsyms_num_syms");
449 printf("\t.long\t%u\n", table_cnt);
450 printf("\n");
451
452 /* table of offset markers, that give the offset in the compressed stream
453 * every 256 symbols */
454 markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
455 if (!markers) {
456 fprintf(stderr, "kallsyms failure: "
457 "unable to allocate required memory\n");
458 exit(EXIT_FAILURE);
459 }
460
461 output_label("kallsyms_names");
462 off = 0;
463 for (i = 0; i < table_cnt; i++) {
464 if ((i & 0xFF) == 0)
465 markers[i >> 8] = off;
466
467 printf("\t.byte 0x%02x", table[i]->len);
468 for (k = 0; k < table[i]->len; k++)
469 printf(", 0x%02x", table[i]->sym[k]);
470 printf("\n");
471
472 off += table[i]->len + 1;
473 }
474 printf("\n");
475
476 output_label("kallsyms_markers");
477 for (i = 0; i < ((table_cnt + 255) >> 8); i++)
478 printf("\t.long\t%u\n", markers[i]);
479 printf("\n");
480
481 free(markers);
482
483 output_label("kallsyms_token_table");
484 off = 0;
485 for (i = 0; i < 256; i++) {
486 best_idx[i] = off;
487 expand_symbol(best_table[i], best_table_len[i], buf);
488 printf("\t.asciz\t\"%s\"\n", buf);
489 off += strlen(buf) + 1;
490 }
491 printf("\n");
492
493 output_label("kallsyms_token_index");
494 for (i = 0; i < 256; i++)
495 printf("\t.short\t%d\n", best_idx[i]);
496 printf("\n");
497}
498
499
500/* table lookup compression functions */
501
502/* count all the possible tokens in a symbol */
503static void learn_symbol(const unsigned char *symbol, int len)
504{
505 int i;
506
507 for (i = 0; i < len - 1; i++)
508 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
509}
510
511/* decrease the count for all the possible tokens in a symbol */
512static void forget_symbol(const unsigned char *symbol, int len)
513{
514 int i;
515
516 for (i = 0; i < len - 1; i++)
517 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
518}
519
520/* do the initial token count */
521static void build_initial_tok_table(void)
522{
523 unsigned int i;
524
525 for (i = 0; i < table_cnt; i++)
526 learn_symbol(table[i]->sym, table[i]->len);
527}
528
529static unsigned char *find_token(unsigned char *str, int len,
530 const unsigned char *token)
531{
532 int i;
533
534 for (i = 0; i < len - 1; i++) {
535 if (str[i] == token[0] && str[i+1] == token[1])
536 return &str[i];
537 }
538 return NULL;
539}
540
541/* replace a given token in all the valid symbols. Use the sampled symbols
542 * to update the counts */
543static void compress_symbols(const unsigned char *str, int idx)
544{
545 unsigned int i, len, size;
546 unsigned char *p1, *p2;
547
548 for (i = 0; i < table_cnt; i++) {
549
550 len = table[i]->len;
551 p1 = table[i]->sym;
552
553 /* find the token on the symbol */
554 p2 = find_token(p1, len, str);
555 if (!p2) continue;
556
557 /* decrease the counts for this symbol's tokens */
558 forget_symbol(table[i]->sym, len);
559
560 size = len;
561
562 do {
563 *p2 = idx;
564 p2++;
565 size -= (p2 - p1);
566 memmove(p2, p2 + 1, size);
567 p1 = p2;
568 len--;
569
570 if (size < 2) break;
571
572 /* find the token on the symbol */
573 p2 = find_token(p1, size, str);
574
575 } while (p2);
576
577 table[i]->len = len;
578
579 /* increase the counts for this symbol's new tokens */
580 learn_symbol(table[i]->sym, len);
581 }
582}
583
584/* search the token with the maximum profit */
585static int find_best_token(void)
586{
587 int i, best, bestprofit;
588
589 bestprofit=-10000;
590 best = 0;
591
592 for (i = 0; i < 0x10000; i++) {
593 if (token_profit[i] > bestprofit) {
594 best = i;
595 bestprofit = token_profit[i];
596 }
597 }
598 return best;
599}
600
601/* this is the core of the algorithm: calculate the "best" table */
602static void optimize_result(void)
603{
604 int i, best;
605
606 /* using the '\0' symbol last allows compress_symbols to use standard
607 * fast string functions */
608 for (i = 255; i >= 0; i--) {
609
610 /* if this table slot is empty (it is not used by an actual
611 * original char code */
612 if (!best_table_len[i]) {
613
614 /* find the token with the best profit value */
615 best = find_best_token();
616 if (token_profit[best] == 0)
617 break;
618
619 /* place it in the "best" table */
620 best_table_len[i] = 2;
621 best_table[i][0] = best & 0xFF;
622 best_table[i][1] = (best >> 8) & 0xFF;
623
624 /* replace this token in all the valid symbols */
625 compress_symbols(best_table[i], i);
626 }
627 }
628}
629
630/* start by placing the symbols that are actually used on the table */
631static void insert_real_symbols_in_table(void)
632{
633 unsigned int i, j, c;
634
635 for (i = 0; i < table_cnt; i++) {
636 for (j = 0; j < table[i]->len; j++) {
637 c = table[i]->sym[j];
638 best_table[c][0]=c;
639 best_table_len[c]=1;
640 }
641 }
642}
643
644static void optimize_token_table(void)
645{
646 build_initial_tok_table();
647
648 insert_real_symbols_in_table();
649
650 optimize_result();
651}
652
653/* guess for "linker script provide" symbol */
654static int may_be_linker_script_provide_symbol(const struct sym_entry *se)
655{
656 const char *symbol = sym_name(se);
657 int len = se->len - 1;
658
659 if (len < 8)
660 return 0;
661
662 if (symbol[0] != '_' || symbol[1] != '_')
663 return 0;
664
665 /* __start_XXXXX */
666 if (!memcmp(symbol + 2, "start_", 6))
667 return 1;
668
669 /* __stop_XXXXX */
670 if (!memcmp(symbol + 2, "stop_", 5))
671 return 1;
672
673 /* __end_XXXXX */
674 if (!memcmp(symbol + 2, "end_", 4))
675 return 1;
676
677 /* __XXXXX_start */
678 if (!memcmp(symbol + len - 6, "_start", 6))
679 return 1;
680
681 /* __XXXXX_end */
682 if (!memcmp(symbol + len - 4, "_end", 4))
683 return 1;
684
685 return 0;
686}
687
688static int compare_symbols(const void *a, const void *b)
689{
690 const struct sym_entry *sa = *(const struct sym_entry **)a;
691 const struct sym_entry *sb = *(const struct sym_entry **)b;
692 int wa, wb;
693
694 /* sort by address first */
695 if (sa->addr > sb->addr)
696 return 1;
697 if (sa->addr < sb->addr)
698 return -1;
699
700 /* sort by "weakness" type */
701 wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
702 wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
703 if (wa != wb)
704 return wa - wb;
705
706 /* sort by "linker script provide" type */
707 wa = may_be_linker_script_provide_symbol(sa);
708 wb = may_be_linker_script_provide_symbol(sb);
709 if (wa != wb)
710 return wa - wb;
711
712 /* sort by the number of prefix underscores */
713 wa = strspn(sym_name(sa), "_");
714 wb = strspn(sym_name(sb), "_");
715 if (wa != wb)
716 return wa - wb;
717
718 /* sort by initial order, so that other symbols are left undisturbed */
719 return sa->start_pos - sb->start_pos;
720}
721
722static void sort_symbols(void)
723{
724 qsort(table, table_cnt, sizeof(table[0]), compare_symbols);
725}
726
727static void make_percpus_absolute(void)
728{
729 unsigned int i;
730
731 for (i = 0; i < table_cnt; i++)
732 if (symbol_in_range(table[i], &percpu_range, 1)) {
733 /*
734 * Keep the 'A' override for percpu symbols to
735 * ensure consistent behavior compared to older
736 * versions of this tool.
737 */
738 table[i]->sym[0] = 'A';
739 table[i]->percpu_absolute = 1;
740 }
741}
742
743/* find the minimum non-absolute symbol address */
744static void record_relative_base(void)
745{
746 unsigned int i;
747
748 for (i = 0; i < table_cnt; i++)
749 if (!symbol_absolute(table[i])) {
750 /*
751 * The table is sorted by address.
752 * Take the first non-absolute symbol value.
753 */
754 relative_base = table[i]->addr;
755 return;
756 }
757}
758
759int main(int argc, char **argv)
760{
761 if (argc >= 2) {
762 int i;
763 for (i = 1; i < argc; i++) {
764 if(strcmp(argv[i], "--all-symbols") == 0)
765 all_symbols = 1;
766 else if (strcmp(argv[i], "--absolute-percpu") == 0)
767 absolute_percpu = 1;
768 else if (strcmp(argv[i], "--base-relative") == 0)
769 base_relative = 1;
770 else
771 usage();
772 }
773 } else if (argc != 1)
774 usage();
775
776 read_map(stdin);
777 shrink_table();
778 if (absolute_percpu)
779 make_percpus_absolute();
780 sort_symbols();
781 if (base_relative)
782 record_relative_base();
783 optimize_token_table();
784 write_src();
785
786 return 0;
787}