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: kallsyms [--all-symbols] [--absolute-percpu]
9 * [--base-relative] [--lto-clang] in.map > out.S
10 *
11 * Table compression uses all the unused char codes on the symbols and
12 * maps these to the most used substrings (tokens). For instance, it might
13 * map char code 0xF7 to represent "write_" and then in every symbol where
14 * "write_" appears it can be replaced by 0xF7, saving 5 bytes.
15 * The used codes themselves are also placed in the table so that the
16 * decompresion can work without "special cases".
17 * Applied to kernel symbols, this usually produces a compression ratio
18 * of about 50%.
19 *
20 */
21
22 #include <getopt.h>
23 #include <stdbool.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <ctype.h>
28 #include <limits.h>
29
30 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
31
32 #define _stringify_1(x) #x
33 #define _stringify(x) _stringify_1(x)
34
35 #define KSYM_NAME_LEN 512
36
37 /*
38 * A substantially bigger size than the current maximum.
39 *
40 * It cannot be defined as an expression because it gets stringified
41 * for the fscanf() format string. Therefore, a _Static_assert() is
42 * used instead to maintain the relationship with KSYM_NAME_LEN.
43 */
44 #define KSYM_NAME_LEN_BUFFER 2048
45 _Static_assert(
46 KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4,
47 "Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN"
48 );
49
50 struct sym_entry {
51 unsigned long long addr;
52 unsigned int len;
53 unsigned int seq;
54 unsigned int start_pos;
55 unsigned int percpu_absolute;
56 unsigned char sym[];
57 };
58
59 struct addr_range {
60 const char *start_sym, *end_sym;
61 unsigned long long start, end;
62 };
63
64 static unsigned long long _text;
65 static unsigned long long relative_base;
66 static struct addr_range text_ranges[] = {
67 { "_stext", "_etext" },
68 { "_sinittext", "_einittext" },
69 };
70 #define text_range_text (&text_ranges[0])
71 #define text_range_inittext (&text_ranges[1])
72
73 static struct addr_range percpu_range = {
74 "__per_cpu_start", "__per_cpu_end", -1ULL, 0
75 };
76
77 static struct sym_entry **table;
78 static unsigned int table_size, table_cnt;
79 static int all_symbols;
80 static int absolute_percpu;
81 static int base_relative;
82 static int lto_clang;
83
84 static int token_profit[0x10000];
85
86 /* the table that holds the result of the compression */
87 static unsigned char best_table[256][2];
88 static unsigned char best_table_len[256];
89
90
usage(void)91 static void usage(void)
92 {
93 fprintf(stderr, "Usage: kallsyms [--all-symbols] [--absolute-percpu] "
94 "[--base-relative] [--lto-clang] in.map > out.S\n");
95 exit(1);
96 }
97
sym_name(const struct sym_entry * s)98 static char *sym_name(const struct sym_entry *s)
99 {
100 return (char *)s->sym + 1;
101 }
102
is_ignored_symbol(const char * name,char type)103 static bool is_ignored_symbol(const char *name, char type)
104 {
105 /* Symbol names that exactly match to the following are ignored.*/
106 static const char * const ignored_symbols[] = {
107 /*
108 * Symbols which vary between passes. Passes 1 and 2 must have
109 * identical symbol lists. The kallsyms_* symbols below are
110 * only added after pass 1, they would be included in pass 2
111 * when --all-symbols is specified so exclude them to get a
112 * stable symbol list.
113 */
114 "kallsyms_addresses",
115 "kallsyms_offsets",
116 "kallsyms_relative_base",
117 "kallsyms_num_syms",
118 "kallsyms_names",
119 "kallsyms_markers",
120 "kallsyms_token_table",
121 "kallsyms_token_index",
122 "kallsyms_seqs_of_names",
123 /* Exclude linker generated symbols which vary between passes */
124 "_SDA_BASE_", /* ppc */
125 "_SDA2_BASE_", /* ppc */
126 NULL
127 };
128
129 /* Symbol names that begin with the following are ignored.*/
130 static const char * const ignored_prefixes[] = {
131 "__efistub_", /* arm64 EFI stub namespace */
132 "__kvm_nvhe_$", /* arm64 local symbols in non-VHE KVM namespace */
133 "__kvm_nvhe_.L", /* arm64 local symbols in non-VHE KVM namespace */
134 "__AArch64ADRPThunk_", /* arm64 lld */
135 "__ARMV5PILongThunk_", /* arm lld */
136 "__ARMV7PILongThunk_",
137 "__ThumbV7PILongThunk_",
138 "__LA25Thunk_", /* mips lld */
139 "__microLA25Thunk_",
140 "__kcfi_typeid_", /* CFI type identifiers */
141 NULL
142 };
143
144 /* Symbol names that end with the following are ignored.*/
145 static const char * const ignored_suffixes[] = {
146 "_from_arm", /* arm */
147 "_from_thumb", /* arm */
148 "_veneer", /* arm */
149 NULL
150 };
151
152 /* Symbol names that contain the following are ignored.*/
153 static const char * const ignored_matches[] = {
154 ".long_branch.", /* ppc stub */
155 ".plt_branch.", /* ppc stub */
156 NULL
157 };
158
159 const char * const *p;
160
161 for (p = ignored_symbols; *p; p++)
162 if (!strcmp(name, *p))
163 return true;
164
165 for (p = ignored_prefixes; *p; p++)
166 if (!strncmp(name, *p, strlen(*p)))
167 return true;
168
169 for (p = ignored_suffixes; *p; p++) {
170 int l = strlen(name) - strlen(*p);
171
172 if (l >= 0 && !strcmp(name + l, *p))
173 return true;
174 }
175
176 for (p = ignored_matches; *p; p++) {
177 if (strstr(name, *p))
178 return true;
179 }
180
181 if (type == 'U' || type == 'u')
182 return true;
183 /* exclude debugging symbols */
184 if (type == 'N' || type == 'n')
185 return true;
186
187 if (toupper(type) == 'A') {
188 /* Keep these useful absolute symbols */
189 if (strcmp(name, "__kernel_syscall_via_break") &&
190 strcmp(name, "__kernel_syscall_via_epc") &&
191 strcmp(name, "__kernel_sigtramp") &&
192 strcmp(name, "__gp"))
193 return true;
194 }
195
196 return false;
197 }
198
check_symbol_range(const char * sym,unsigned long long addr,struct addr_range * ranges,int entries)199 static void check_symbol_range(const char *sym, unsigned long long addr,
200 struct addr_range *ranges, int entries)
201 {
202 size_t i;
203 struct addr_range *ar;
204
205 for (i = 0; i < entries; ++i) {
206 ar = &ranges[i];
207
208 if (strcmp(sym, ar->start_sym) == 0) {
209 ar->start = addr;
210 return;
211 } else if (strcmp(sym, ar->end_sym) == 0) {
212 ar->end = addr;
213 return;
214 }
215 }
216 }
217
read_symbol(FILE * in)218 static struct sym_entry *read_symbol(FILE *in)
219 {
220 char name[KSYM_NAME_LEN_BUFFER+1], type;
221 unsigned long long addr;
222 unsigned int len;
223 struct sym_entry *sym;
224 int rc;
225
226 rc = fscanf(in, "%llx %c %" _stringify(KSYM_NAME_LEN_BUFFER) "s\n", &addr, &type, name);
227 if (rc != 3) {
228 if (rc != EOF && fgets(name, ARRAY_SIZE(name), in) == NULL)
229 fprintf(stderr, "Read error or end of file.\n");
230 return NULL;
231 }
232 if (strlen(name) >= KSYM_NAME_LEN) {
233 fprintf(stderr, "Symbol %s too long for kallsyms (%zu >= %d).\n"
234 "Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",
235 name, strlen(name), KSYM_NAME_LEN);
236 return NULL;
237 }
238
239 if (strcmp(name, "_text") == 0)
240 _text = addr;
241
242 /* Ignore most absolute/undefined (?) symbols. */
243 if (is_ignored_symbol(name, type))
244 return NULL;
245
246 check_symbol_range(name, addr, text_ranges, ARRAY_SIZE(text_ranges));
247 check_symbol_range(name, addr, &percpu_range, 1);
248
249 /* include the type field in the symbol name, so that it gets
250 * compressed together */
251
252 len = strlen(name) + 1;
253
254 sym = malloc(sizeof(*sym) + len + 1);
255 if (!sym) {
256 fprintf(stderr, "kallsyms failure: "
257 "unable to allocate required amount of memory\n");
258 exit(EXIT_FAILURE);
259 }
260 sym->addr = addr;
261 sym->len = len;
262 sym->sym[0] = type;
263 strcpy(sym_name(sym), name);
264 sym->percpu_absolute = 0;
265
266 return sym;
267 }
268
symbol_in_range(const struct sym_entry * s,const struct addr_range * ranges,int entries)269 static int symbol_in_range(const struct sym_entry *s,
270 const struct addr_range *ranges, int entries)
271 {
272 size_t i;
273 const struct addr_range *ar;
274
275 for (i = 0; i < entries; ++i) {
276 ar = &ranges[i];
277
278 if (s->addr >= ar->start && s->addr <= ar->end)
279 return 1;
280 }
281
282 return 0;
283 }
284
symbol_valid(const struct sym_entry * s)285 static int symbol_valid(const struct sym_entry *s)
286 {
287 const char *name = sym_name(s);
288
289 /* if --all-symbols is not specified, then symbols outside the text
290 * and inittext sections are discarded */
291 if (!all_symbols) {
292 if (symbol_in_range(s, text_ranges,
293 ARRAY_SIZE(text_ranges)) == 0)
294 return 0;
295 /* Corner case. Discard any symbols with the same value as
296 * _etext _einittext; they can move between pass 1 and 2 when
297 * the kallsyms data are added. If these symbols move then
298 * they may get dropped in pass 2, which breaks the kallsyms
299 * rules.
300 */
301 if ((s->addr == text_range_text->end &&
302 strcmp(name, text_range_text->end_sym)) ||
303 (s->addr == text_range_inittext->end &&
304 strcmp(name, text_range_inittext->end_sym)))
305 return 0;
306 }
307
308 return 1;
309 }
310
311 /* remove all the invalid symbols from the table */
shrink_table(void)312 static void shrink_table(void)
313 {
314 unsigned int i, pos;
315
316 pos = 0;
317 for (i = 0; i < table_cnt; i++) {
318 if (symbol_valid(table[i])) {
319 if (pos != i)
320 table[pos] = table[i];
321 pos++;
322 } else {
323 free(table[i]);
324 }
325 }
326 table_cnt = pos;
327
328 /* When valid symbol is not registered, exit to error */
329 if (!table_cnt) {
330 fprintf(stderr, "No valid symbol.\n");
331 exit(1);
332 }
333 }
334
read_map(const char * in)335 static void read_map(const char *in)
336 {
337 FILE *fp;
338 struct sym_entry *sym;
339
340 fp = fopen(in, "r");
341 if (!fp) {
342 perror(in);
343 exit(1);
344 }
345
346 while (!feof(fp)) {
347 sym = read_symbol(fp);
348 if (!sym)
349 continue;
350
351 sym->start_pos = table_cnt;
352
353 if (table_cnt >= table_size) {
354 table_size += 10000;
355 table = realloc(table, sizeof(*table) * table_size);
356 if (!table) {
357 fprintf(stderr, "out of memory\n");
358 fclose(fp);
359 exit (1);
360 }
361 }
362
363 table[table_cnt++] = sym;
364 }
365
366 fclose(fp);
367 }
368
output_label(const char * label)369 static void output_label(const char *label)
370 {
371 printf(".globl %s\n", label);
372 printf("\tALGN\n");
373 printf("%s:\n", label);
374 }
375
376 /* Provide proper symbols relocatability by their '_text' relativeness. */
output_address(unsigned long long addr)377 static void output_address(unsigned long long addr)
378 {
379 if (_text <= addr)
380 printf("\tPTR\t_text + %#llx\n", addr - _text);
381 else
382 printf("\tPTR\t_text - %#llx\n", _text - addr);
383 }
384
385 /* uncompress a compressed symbol. When this function is called, the best table
386 * might still be compressed itself, so the function needs to be recursive */
expand_symbol(const unsigned char * data,int len,char * result)387 static int expand_symbol(const unsigned char *data, int len, char *result)
388 {
389 int c, rlen, total=0;
390
391 while (len) {
392 c = *data;
393 /* if the table holds a single char that is the same as the one
394 * we are looking for, then end the search */
395 if (best_table[c][0]==c && best_table_len[c]==1) {
396 *result++ = c;
397 total++;
398 } else {
399 /* if not, recurse and expand */
400 rlen = expand_symbol(best_table[c], best_table_len[c], result);
401 total += rlen;
402 result += rlen;
403 }
404 data++;
405 len--;
406 }
407 *result=0;
408
409 return total;
410 }
411
symbol_absolute(const struct sym_entry * s)412 static int symbol_absolute(const struct sym_entry *s)
413 {
414 return s->percpu_absolute;
415 }
416
s_name(char * buf)417 static char * s_name(char *buf)
418 {
419 /* Skip the symbol type */
420 return buf + 1;
421 }
422
cleanup_symbol_name(char * s)423 static void cleanup_symbol_name(char *s)
424 {
425 char *p;
426
427 if (!lto_clang)
428 return;
429
430 /*
431 * ASCII[.] = 2e
432 * ASCII[0-9] = 30,39
433 * ASCII[A-Z] = 41,5a
434 * ASCII[_] = 5f
435 * ASCII[a-z] = 61,7a
436 *
437 * As above, replacing the first '.' in ".llvm." with '\0' does not
438 * affect the main sorting, but it helps us with subsorting.
439 */
440 p = strstr(s, ".llvm.");
441 if (p)
442 *p = '\0';
443 }
444
compare_names(const void * a,const void * b)445 static int compare_names(const void *a, const void *b)
446 {
447 int ret;
448 char sa_namebuf[KSYM_NAME_LEN];
449 char sb_namebuf[KSYM_NAME_LEN];
450 const struct sym_entry *sa = *(const struct sym_entry **)a;
451 const struct sym_entry *sb = *(const struct sym_entry **)b;
452
453 expand_symbol(sa->sym, sa->len, sa_namebuf);
454 expand_symbol(sb->sym, sb->len, sb_namebuf);
455 cleanup_symbol_name(s_name(sa_namebuf));
456 cleanup_symbol_name(s_name(sb_namebuf));
457 ret = strcmp(s_name(sa_namebuf), s_name(sb_namebuf));
458 if (!ret) {
459 if (sa->addr > sb->addr)
460 return 1;
461 else if (sa->addr < sb->addr)
462 return -1;
463
464 /* keep old order */
465 return (int)(sa->seq - sb->seq);
466 }
467
468 return ret;
469 }
470
sort_symbols_by_name(void)471 static void sort_symbols_by_name(void)
472 {
473 qsort(table, table_cnt, sizeof(table[0]), compare_names);
474 }
475
write_src(void)476 static void write_src(void)
477 {
478 unsigned int i, k, off;
479 unsigned int best_idx[256];
480 unsigned int *markers;
481 char buf[KSYM_NAME_LEN];
482
483 printf("#include <asm/bitsperlong.h>\n");
484 printf("#if BITS_PER_LONG == 64\n");
485 printf("#define PTR .quad\n");
486 printf("#define ALGN .balign 8\n");
487 printf("#else\n");
488 printf("#define PTR .long\n");
489 printf("#define ALGN .balign 4\n");
490 printf("#endif\n");
491
492 printf("\t.section .rodata, \"a\"\n");
493
494 if (!base_relative)
495 output_label("kallsyms_addresses");
496 else
497 output_label("kallsyms_offsets");
498
499 for (i = 0; i < table_cnt; i++) {
500 if (base_relative) {
501 /*
502 * Use the offset relative to the lowest value
503 * encountered of all relative symbols, and emit
504 * non-relocatable fixed offsets that will be fixed
505 * up at runtime.
506 */
507
508 long long offset;
509 int overflow;
510
511 if (!absolute_percpu) {
512 offset = table[i]->addr - relative_base;
513 overflow = (offset < 0 || offset > UINT_MAX);
514 } else if (symbol_absolute(table[i])) {
515 offset = table[i]->addr;
516 overflow = (offset < 0 || offset > INT_MAX);
517 } else {
518 offset = relative_base - table[i]->addr - 1;
519 overflow = (offset < INT_MIN || offset >= 0);
520 }
521 if (overflow) {
522 fprintf(stderr, "kallsyms failure: "
523 "%s symbol value %#llx out of range in relative mode\n",
524 symbol_absolute(table[i]) ? "absolute" : "relative",
525 table[i]->addr);
526 exit(EXIT_FAILURE);
527 }
528 printf("\t.long\t%#x\n", (int)offset);
529 } else if (!symbol_absolute(table[i])) {
530 output_address(table[i]->addr);
531 } else {
532 printf("\tPTR\t%#llx\n", table[i]->addr);
533 }
534 }
535 printf("\n");
536
537 if (base_relative) {
538 output_label("kallsyms_relative_base");
539 output_address(relative_base);
540 printf("\n");
541 }
542
543 output_label("kallsyms_num_syms");
544 printf("\t.long\t%u\n", table_cnt);
545 printf("\n");
546
547 /* table of offset markers, that give the offset in the compressed stream
548 * every 256 symbols */
549 markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
550 if (!markers) {
551 fprintf(stderr, "kallsyms failure: "
552 "unable to allocate required memory\n");
553 exit(EXIT_FAILURE);
554 }
555
556 output_label("kallsyms_names");
557 off = 0;
558 for (i = 0; i < table_cnt; i++) {
559 if ((i & 0xFF) == 0)
560 markers[i >> 8] = off;
561 table[i]->seq = i;
562
563 /* There cannot be any symbol of length zero. */
564 if (table[i]->len == 0) {
565 fprintf(stderr, "kallsyms failure: "
566 "unexpected zero symbol length\n");
567 exit(EXIT_FAILURE);
568 }
569
570 /* Only lengths that fit in up-to-two-byte ULEB128 are supported. */
571 if (table[i]->len > 0x3FFF) {
572 fprintf(stderr, "kallsyms failure: "
573 "unexpected huge symbol length\n");
574 exit(EXIT_FAILURE);
575 }
576
577 /* Encode length with ULEB128. */
578 if (table[i]->len <= 0x7F) {
579 /* Most symbols use a single byte for the length. */
580 printf("\t.byte 0x%02x", table[i]->len);
581 off += table[i]->len + 1;
582 } else {
583 /* "Big" symbols use two bytes. */
584 printf("\t.byte 0x%02x, 0x%02x",
585 (table[i]->len & 0x7F) | 0x80,
586 (table[i]->len >> 7) & 0x7F);
587 off += table[i]->len + 2;
588 }
589 for (k = 0; k < table[i]->len; k++)
590 printf(", 0x%02x", table[i]->sym[k]);
591 printf("\n");
592 }
593 printf("\n");
594
595 output_label("kallsyms_markers");
596 for (i = 0; i < ((table_cnt + 255) >> 8); i++)
597 printf("\t.long\t%u\n", markers[i]);
598 printf("\n");
599
600 free(markers);
601
602 sort_symbols_by_name();
603 output_label("kallsyms_seqs_of_names");
604 for (i = 0; i < table_cnt; i++)
605 printf("\t.byte 0x%02x, 0x%02x, 0x%02x\n",
606 (unsigned char)(table[i]->seq >> 16),
607 (unsigned char)(table[i]->seq >> 8),
608 (unsigned char)(table[i]->seq >> 0));
609 printf("\n");
610
611 output_label("kallsyms_token_table");
612 off = 0;
613 for (i = 0; i < 256; i++) {
614 best_idx[i] = off;
615 expand_symbol(best_table[i], best_table_len[i], buf);
616 printf("\t.asciz\t\"%s\"\n", buf);
617 off += strlen(buf) + 1;
618 }
619 printf("\n");
620
621 output_label("kallsyms_token_index");
622 for (i = 0; i < 256; i++)
623 printf("\t.short\t%d\n", best_idx[i]);
624 printf("\n");
625 }
626
627
628 /* table lookup compression functions */
629
630 /* count all the possible tokens in a symbol */
learn_symbol(const unsigned char * symbol,int len)631 static void learn_symbol(const unsigned char *symbol, int len)
632 {
633 int i;
634
635 for (i = 0; i < len - 1; i++)
636 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
637 }
638
639 /* decrease the count for all the possible tokens in a symbol */
forget_symbol(const unsigned char * symbol,int len)640 static void forget_symbol(const unsigned char *symbol, int len)
641 {
642 int i;
643
644 for (i = 0; i < len - 1; i++)
645 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
646 }
647
648 /* do the initial token count */
build_initial_tok_table(void)649 static void build_initial_tok_table(void)
650 {
651 unsigned int i;
652
653 for (i = 0; i < table_cnt; i++)
654 learn_symbol(table[i]->sym, table[i]->len);
655 }
656
find_token(unsigned char * str,int len,const unsigned char * token)657 static unsigned char *find_token(unsigned char *str, int len,
658 const unsigned char *token)
659 {
660 int i;
661
662 for (i = 0; i < len - 1; i++) {
663 if (str[i] == token[0] && str[i+1] == token[1])
664 return &str[i];
665 }
666 return NULL;
667 }
668
669 /* replace a given token in all the valid symbols. Use the sampled symbols
670 * to update the counts */
compress_symbols(const unsigned char * str,int idx)671 static void compress_symbols(const unsigned char *str, int idx)
672 {
673 unsigned int i, len, size;
674 unsigned char *p1, *p2;
675
676 for (i = 0; i < table_cnt; i++) {
677
678 len = table[i]->len;
679 p1 = table[i]->sym;
680
681 /* find the token on the symbol */
682 p2 = find_token(p1, len, str);
683 if (!p2) continue;
684
685 /* decrease the counts for this symbol's tokens */
686 forget_symbol(table[i]->sym, len);
687
688 size = len;
689
690 do {
691 *p2 = idx;
692 p2++;
693 size -= (p2 - p1);
694 memmove(p2, p2 + 1, size);
695 p1 = p2;
696 len--;
697
698 if (size < 2) break;
699
700 /* find the token on the symbol */
701 p2 = find_token(p1, size, str);
702
703 } while (p2);
704
705 table[i]->len = len;
706
707 /* increase the counts for this symbol's new tokens */
708 learn_symbol(table[i]->sym, len);
709 }
710 }
711
712 /* search the token with the maximum profit */
find_best_token(void)713 static int find_best_token(void)
714 {
715 int i, best, bestprofit;
716
717 bestprofit=-10000;
718 best = 0;
719
720 for (i = 0; i < 0x10000; i++) {
721 if (token_profit[i] > bestprofit) {
722 best = i;
723 bestprofit = token_profit[i];
724 }
725 }
726 return best;
727 }
728
729 /* this is the core of the algorithm: calculate the "best" table */
optimize_result(void)730 static void optimize_result(void)
731 {
732 int i, best;
733
734 /* using the '\0' symbol last allows compress_symbols to use standard
735 * fast string functions */
736 for (i = 255; i >= 0; i--) {
737
738 /* if this table slot is empty (it is not used by an actual
739 * original char code */
740 if (!best_table_len[i]) {
741
742 /* find the token with the best profit value */
743 best = find_best_token();
744 if (token_profit[best] == 0)
745 break;
746
747 /* place it in the "best" table */
748 best_table_len[i] = 2;
749 best_table[i][0] = best & 0xFF;
750 best_table[i][1] = (best >> 8) & 0xFF;
751
752 /* replace this token in all the valid symbols */
753 compress_symbols(best_table[i], i);
754 }
755 }
756 }
757
758 /* start by placing the symbols that are actually used on the table */
insert_real_symbols_in_table(void)759 static void insert_real_symbols_in_table(void)
760 {
761 unsigned int i, j, c;
762
763 for (i = 0; i < table_cnt; i++) {
764 for (j = 0; j < table[i]->len; j++) {
765 c = table[i]->sym[j];
766 best_table[c][0]=c;
767 best_table_len[c]=1;
768 }
769 }
770 }
771
optimize_token_table(void)772 static void optimize_token_table(void)
773 {
774 build_initial_tok_table();
775
776 insert_real_symbols_in_table();
777
778 optimize_result();
779 }
780
781 /* guess for "linker script provide" symbol */
may_be_linker_script_provide_symbol(const struct sym_entry * se)782 static int may_be_linker_script_provide_symbol(const struct sym_entry *se)
783 {
784 const char *symbol = sym_name(se);
785 int len = se->len - 1;
786
787 if (len < 8)
788 return 0;
789
790 if (symbol[0] != '_' || symbol[1] != '_')
791 return 0;
792
793 /* __start_XXXXX */
794 if (!memcmp(symbol + 2, "start_", 6))
795 return 1;
796
797 /* __stop_XXXXX */
798 if (!memcmp(symbol + 2, "stop_", 5))
799 return 1;
800
801 /* __end_XXXXX */
802 if (!memcmp(symbol + 2, "end_", 4))
803 return 1;
804
805 /* __XXXXX_start */
806 if (!memcmp(symbol + len - 6, "_start", 6))
807 return 1;
808
809 /* __XXXXX_end */
810 if (!memcmp(symbol + len - 4, "_end", 4))
811 return 1;
812
813 return 0;
814 }
815
compare_symbols(const void * a,const void * b)816 static int compare_symbols(const void *a, const void *b)
817 {
818 const struct sym_entry *sa = *(const struct sym_entry **)a;
819 const struct sym_entry *sb = *(const struct sym_entry **)b;
820 int wa, wb;
821
822 /* sort by address first */
823 if (sa->addr > sb->addr)
824 return 1;
825 if (sa->addr < sb->addr)
826 return -1;
827
828 /* sort by "weakness" type */
829 wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
830 wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
831 if (wa != wb)
832 return wa - wb;
833
834 /* sort by "linker script provide" type */
835 wa = may_be_linker_script_provide_symbol(sa);
836 wb = may_be_linker_script_provide_symbol(sb);
837 if (wa != wb)
838 return wa - wb;
839
840 /* sort by the number of prefix underscores */
841 wa = strspn(sym_name(sa), "_");
842 wb = strspn(sym_name(sb), "_");
843 if (wa != wb)
844 return wa - wb;
845
846 /* sort by initial order, so that other symbols are left undisturbed */
847 return sa->start_pos - sb->start_pos;
848 }
849
sort_symbols(void)850 static void sort_symbols(void)
851 {
852 qsort(table, table_cnt, sizeof(table[0]), compare_symbols);
853 }
854
make_percpus_absolute(void)855 static void make_percpus_absolute(void)
856 {
857 unsigned int i;
858
859 for (i = 0; i < table_cnt; i++)
860 if (symbol_in_range(table[i], &percpu_range, 1)) {
861 /*
862 * Keep the 'A' override for percpu symbols to
863 * ensure consistent behavior compared to older
864 * versions of this tool.
865 */
866 table[i]->sym[0] = 'A';
867 table[i]->percpu_absolute = 1;
868 }
869 }
870
871 /* find the minimum non-absolute symbol address */
record_relative_base(void)872 static void record_relative_base(void)
873 {
874 unsigned int i;
875
876 for (i = 0; i < table_cnt; i++)
877 if (!symbol_absolute(table[i])) {
878 /*
879 * The table is sorted by address.
880 * Take the first non-absolute symbol value.
881 */
882 relative_base = table[i]->addr;
883 return;
884 }
885 }
886
main(int argc,char ** argv)887 int main(int argc, char **argv)
888 {
889 while (1) {
890 static struct option long_options[] = {
891 {"all-symbols", no_argument, &all_symbols, 1},
892 {"absolute-percpu", no_argument, &absolute_percpu, 1},
893 {"base-relative", no_argument, &base_relative, 1},
894 {"lto-clang", no_argument, <o_clang, 1},
895 {},
896 };
897
898 int c = getopt_long(argc, argv, "", long_options, NULL);
899
900 if (c == -1)
901 break;
902 if (c != 0)
903 usage();
904 }
905
906 if (optind >= argc)
907 usage();
908
909 read_map(argv[optind]);
910 shrink_table();
911 if (absolute_percpu)
912 make_percpus_absolute();
913 sort_symbols();
914 if (base_relative)
915 record_relative_base();
916 optimize_token_table();
917 write_src();
918
919 return 0;
920 }
921