xref: /openbmc/linux/scripts/kallsyms.c (revision 2d972b6a)
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 #include <limits.h>
26 
27 #ifndef ARRAY_SIZE
28 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
29 #endif
30 
31 #define KSYM_NAME_LEN		128
32 
33 struct sym_entry {
34 	unsigned long long addr;
35 	unsigned int len;
36 	unsigned int start_pos;
37 	unsigned char *sym;
38 	unsigned int percpu_absolute;
39 };
40 
41 struct addr_range {
42 	const char *start_sym, *end_sym;
43 	unsigned long long start, end;
44 };
45 
46 static unsigned long long _text;
47 static unsigned long long relative_base;
48 static struct addr_range text_ranges[] = {
49 	{ "_stext",     "_etext"     },
50 	{ "_sinittext", "_einittext" },
51 	{ "_stext_l1",  "_etext_l1"  },	/* Blackfin on-chip L1 inst SRAM */
52 	{ "_stext_l2",  "_etext_l2"  },	/* Blackfin on-chip L2 SRAM */
53 };
54 #define text_range_text     (&text_ranges[0])
55 #define text_range_inittext (&text_ranges[1])
56 
57 static struct addr_range percpu_range = {
58 	"__per_cpu_start", "__per_cpu_end", -1ULL, 0
59 };
60 
61 static struct sym_entry *table;
62 static unsigned int table_size, table_cnt;
63 static int all_symbols = 0;
64 static int absolute_percpu = 0;
65 static char symbol_prefix_char = '\0';
66 static int base_relative = 0;
67 
68 int token_profit[0x10000];
69 
70 /* the table that holds the result of the compression */
71 unsigned char best_table[256][2];
72 unsigned char best_table_len[256];
73 
74 
75 static void usage(void)
76 {
77 	fprintf(stderr, "Usage: kallsyms [--all-symbols] "
78 			"[--symbol-prefix=<prefix char>] "
79 			"[--base-relative] < in.map > out.S\n");
80 	exit(1);
81 }
82 
83 /*
84  * This ignores the intensely annoying "mapping symbols" found
85  * in ARM ELF files: $a, $t and $d.
86  */
87 static inline int is_arm_mapping_symbol(const char *str)
88 {
89 	return str[0] == '$' && strchr("axtd", str[1])
90 	       && (str[2] == '\0' || str[2] == '.');
91 }
92 
93 static int check_symbol_range(const char *sym, unsigned long long addr,
94 			      struct addr_range *ranges, int entries)
95 {
96 	size_t i;
97 	struct addr_range *ar;
98 
99 	for (i = 0; i < entries; ++i) {
100 		ar = &ranges[i];
101 
102 		if (strcmp(sym, ar->start_sym) == 0) {
103 			ar->start = addr;
104 			return 0;
105 		} else if (strcmp(sym, ar->end_sym) == 0) {
106 			ar->end = addr;
107 			return 0;
108 		}
109 	}
110 
111 	return 1;
112 }
113 
114 static int read_symbol(FILE *in, struct sym_entry *s)
115 {
116 	char str[500];
117 	char *sym, stype;
118 	int rc;
119 
120 	rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str);
121 	if (rc != 3) {
122 		if (rc != EOF && fgets(str, 500, in) == NULL)
123 			fprintf(stderr, "Read error or end of file.\n");
124 		return -1;
125 	}
126 	if (strlen(str) > KSYM_NAME_LEN) {
127 		fprintf(stderr, "Symbol %s too long for kallsyms (%zu vs %d).\n"
128 				"Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",
129 			str, strlen(str), KSYM_NAME_LEN);
130 		return -1;
131 	}
132 
133 	sym = str;
134 	/* skip prefix char */
135 	if (symbol_prefix_char && str[0] == symbol_prefix_char)
136 		sym++;
137 
138 	/* Ignore most absolute/undefined (?) symbols. */
139 	if (strcmp(sym, "_text") == 0)
140 		_text = s->addr;
141 	else if (check_symbol_range(sym, s->addr, text_ranges,
142 				    ARRAY_SIZE(text_ranges)) == 0)
143 		/* nothing to do */;
144 	else if (toupper(stype) == 'A')
145 	{
146 		/* Keep these useful absolute symbols */
147 		if (strcmp(sym, "__kernel_syscall_via_break") &&
148 		    strcmp(sym, "__kernel_syscall_via_epc") &&
149 		    strcmp(sym, "__kernel_sigtramp") &&
150 		    strcmp(sym, "__gp"))
151 			return -1;
152 
153 	}
154 	else if (toupper(stype) == 'U' ||
155 		 is_arm_mapping_symbol(sym))
156 		return -1;
157 	/* exclude also MIPS ELF local symbols ($L123 instead of .L123) */
158 	else if (str[0] == '$')
159 		return -1;
160 	/* exclude debugging symbols */
161 	else if (stype == 'N' || stype == 'n')
162 		return -1;
163 
164 	/* include the type field in the symbol name, so that it gets
165 	 * compressed together */
166 	s->len = strlen(str) + 1;
167 	s->sym = malloc(s->len + 1);
168 	if (!s->sym) {
169 		fprintf(stderr, "kallsyms failure: "
170 			"unable to allocate required amount of memory\n");
171 		exit(EXIT_FAILURE);
172 	}
173 	strcpy((char *)s->sym + 1, str);
174 	s->sym[0] = stype;
175 
176 	s->percpu_absolute = 0;
177 
178 	/* Record if we've found __per_cpu_start/end. */
179 	check_symbol_range(sym, s->addr, &percpu_range, 1);
180 
181 	return 0;
182 }
183 
184 static int symbol_in_range(struct sym_entry *s, struct addr_range *ranges,
185 			   int entries)
186 {
187 	size_t i;
188 	struct addr_range *ar;
189 
190 	for (i = 0; i < entries; ++i) {
191 		ar = &ranges[i];
192 
193 		if (s->addr >= ar->start && s->addr <= ar->end)
194 			return 1;
195 	}
196 
197 	return 0;
198 }
199 
200 static int symbol_valid(struct sym_entry *s)
201 {
202 	/* Symbols which vary between passes.  Passes 1 and 2 must have
203 	 * identical symbol lists.  The kallsyms_* symbols below are only added
204 	 * after pass 1, they would be included in pass 2 when --all-symbols is
205 	 * specified so exclude them to get a stable symbol list.
206 	 */
207 	static char *special_symbols[] = {
208 		"kallsyms_addresses",
209 		"kallsyms_offsets",
210 		"kallsyms_relative_base",
211 		"kallsyms_num_syms",
212 		"kallsyms_names",
213 		"kallsyms_markers",
214 		"kallsyms_token_table",
215 		"kallsyms_token_index",
216 
217 	/* Exclude linker generated symbols which vary between passes */
218 		"_SDA_BASE_",		/* ppc */
219 		"_SDA2_BASE_",		/* ppc */
220 		NULL };
221 
222 	static char *special_prefixes[] = {
223 		"__crc_",		/* modversions */
224 		"__efistub_",		/* arm64 EFI stub namespace */
225 		NULL };
226 
227 	static char *special_suffixes[] = {
228 		"_veneer",		/* arm */
229 		"_from_arm",		/* arm */
230 		"_from_thumb",		/* arm */
231 		NULL };
232 
233 	int i;
234 	char *sym_name = (char *)s->sym + 1;
235 
236 	/* skip prefix char */
237 	if (symbol_prefix_char && *sym_name == symbol_prefix_char)
238 		sym_name++;
239 
240 
241 	/* if --all-symbols is not specified, then symbols outside the text
242 	 * and inittext sections are discarded */
243 	if (!all_symbols) {
244 		if (symbol_in_range(s, text_ranges,
245 				    ARRAY_SIZE(text_ranges)) == 0)
246 			return 0;
247 		/* Corner case.  Discard any symbols with the same value as
248 		 * _etext _einittext; they can move between pass 1 and 2 when
249 		 * the kallsyms data are added.  If these symbols move then
250 		 * they may get dropped in pass 2, which breaks the kallsyms
251 		 * rules.
252 		 */
253 		if ((s->addr == text_range_text->end &&
254 				strcmp(sym_name,
255 				       text_range_text->end_sym)) ||
256 		    (s->addr == text_range_inittext->end &&
257 				strcmp(sym_name,
258 				       text_range_inittext->end_sym)))
259 			return 0;
260 	}
261 
262 	/* Exclude symbols which vary between passes. */
263 	for (i = 0; special_symbols[i]; i++)
264 		if (strcmp(sym_name, special_symbols[i]) == 0)
265 			return 0;
266 
267 	for (i = 0; special_prefixes[i]; i++) {
268 		int l = strlen(special_prefixes[i]);
269 
270 		if (l <= strlen(sym_name) &&
271 		    strncmp(sym_name, special_prefixes[i], l) == 0)
272 			return 0;
273 	}
274 
275 	for (i = 0; special_suffixes[i]; i++) {
276 		int l = strlen(sym_name) - strlen(special_suffixes[i]);
277 
278 		if (l >= 0 && strcmp(sym_name + l, special_suffixes[i]) == 0)
279 			return 0;
280 	}
281 
282 	return 1;
283 }
284 
285 static void read_map(FILE *in)
286 {
287 	while (!feof(in)) {
288 		if (table_cnt >= table_size) {
289 			table_size += 10000;
290 			table = realloc(table, sizeof(*table) * table_size);
291 			if (!table) {
292 				fprintf(stderr, "out of memory\n");
293 				exit (1);
294 			}
295 		}
296 		if (read_symbol(in, &table[table_cnt]) == 0) {
297 			table[table_cnt].start_pos = table_cnt;
298 			table_cnt++;
299 		}
300 	}
301 }
302 
303 static void output_label(char *label)
304 {
305 	if (symbol_prefix_char)
306 		printf(".globl %c%s\n", symbol_prefix_char, label);
307 	else
308 		printf(".globl %s\n", label);
309 	printf("\tALGN\n");
310 	if (symbol_prefix_char)
311 		printf("%c%s:\n", symbol_prefix_char, label);
312 	else
313 		printf("%s:\n", label);
314 }
315 
316 /* uncompress a compressed symbol. When this function is called, the best table
317  * might still be compressed itself, so the function needs to be recursive */
318 static int expand_symbol(unsigned char *data, int len, char *result)
319 {
320 	int c, rlen, total=0;
321 
322 	while (len) {
323 		c = *data;
324 		/* if the table holds a single char that is the same as the one
325 		 * we are looking for, then end the search */
326 		if (best_table[c][0]==c && best_table_len[c]==1) {
327 			*result++ = c;
328 			total++;
329 		} else {
330 			/* if not, recurse and expand */
331 			rlen = expand_symbol(best_table[c], best_table_len[c], result);
332 			total += rlen;
333 			result += rlen;
334 		}
335 		data++;
336 		len--;
337 	}
338 	*result=0;
339 
340 	return total;
341 }
342 
343 static int symbol_absolute(struct sym_entry *s)
344 {
345 	return s->percpu_absolute;
346 }
347 
348 static void write_src(void)
349 {
350 	unsigned int i, k, off;
351 	unsigned int best_idx[256];
352 	unsigned int *markers;
353 	char buf[KSYM_NAME_LEN];
354 
355 	printf("#include <asm/types.h>\n");
356 	printf("#if BITS_PER_LONG == 64\n");
357 	printf("#define PTR .quad\n");
358 	printf("#define ALGN .align 8\n");
359 	printf("#else\n");
360 	printf("#define PTR .long\n");
361 	printf("#define ALGN .align 4\n");
362 	printf("#endif\n");
363 
364 	printf("\t.section .rodata, \"a\"\n");
365 
366 	/* Provide proper symbols relocatability by their relativeness
367 	 * to a fixed anchor point in the runtime image, either '_text'
368 	 * for absolute address tables, in which case the linker will
369 	 * emit the final addresses at build time. Otherwise, use the
370 	 * offset relative to the lowest value encountered of all relative
371 	 * symbols, and emit non-relocatable fixed offsets that will be fixed
372 	 * up at runtime.
373 	 *
374 	 * The symbol names cannot be used to construct normal symbol
375 	 * references as the list of symbols contains symbols that are
376 	 * declared static and are private to their .o files.  This prevents
377 	 * .tmp_kallsyms.o or any other object from referencing them.
378 	 */
379 	if (!base_relative)
380 		output_label("kallsyms_addresses");
381 	else
382 		output_label("kallsyms_offsets");
383 
384 	for (i = 0; i < table_cnt; i++) {
385 		if (base_relative) {
386 			long long offset;
387 			int overflow;
388 
389 			if (!absolute_percpu) {
390 				offset = table[i].addr - relative_base;
391 				overflow = (offset < 0 || offset > UINT_MAX);
392 			} else if (symbol_absolute(&table[i])) {
393 				offset = table[i].addr;
394 				overflow = (offset < 0 || offset > INT_MAX);
395 			} else {
396 				offset = relative_base - table[i].addr - 1;
397 				overflow = (offset < INT_MIN || offset >= 0);
398 			}
399 			if (overflow) {
400 				fprintf(stderr, "kallsyms failure: "
401 					"%s symbol value %#llx out of range in relative mode\n",
402 					symbol_absolute(&table[i]) ? "absolute" : "relative",
403 					table[i].addr);
404 				exit(EXIT_FAILURE);
405 			}
406 			printf("\t.long\t%#x\n", (int)offset);
407 		} else if (!symbol_absolute(&table[i])) {
408 			if (_text <= table[i].addr)
409 				printf("\tPTR\t_text + %#llx\n",
410 					table[i].addr - _text);
411 			else
412 				printf("\tPTR\t_text - %#llx\n",
413 					_text - table[i].addr);
414 		} else {
415 			printf("\tPTR\t%#llx\n", table[i].addr);
416 		}
417 	}
418 	printf("\n");
419 
420 	if (base_relative) {
421 		output_label("kallsyms_relative_base");
422 		printf("\tPTR\t_text - %#llx\n", _text - relative_base);
423 		printf("\n");
424 	}
425 
426 	output_label("kallsyms_num_syms");
427 	printf("\tPTR\t%d\n", table_cnt);
428 	printf("\n");
429 
430 	/* table of offset markers, that give the offset in the compressed stream
431 	 * every 256 symbols */
432 	markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
433 	if (!markers) {
434 		fprintf(stderr, "kallsyms failure: "
435 			"unable to allocate required memory\n");
436 		exit(EXIT_FAILURE);
437 	}
438 
439 	output_label("kallsyms_names");
440 	off = 0;
441 	for (i = 0; i < table_cnt; i++) {
442 		if ((i & 0xFF) == 0)
443 			markers[i >> 8] = off;
444 
445 		printf("\t.byte 0x%02x", table[i].len);
446 		for (k = 0; k < table[i].len; k++)
447 			printf(", 0x%02x", table[i].sym[k]);
448 		printf("\n");
449 
450 		off += table[i].len + 1;
451 	}
452 	printf("\n");
453 
454 	output_label("kallsyms_markers");
455 	for (i = 0; i < ((table_cnt + 255) >> 8); i++)
456 		printf("\tPTR\t%d\n", markers[i]);
457 	printf("\n");
458 
459 	free(markers);
460 
461 	output_label("kallsyms_token_table");
462 	off = 0;
463 	for (i = 0; i < 256; i++) {
464 		best_idx[i] = off;
465 		expand_symbol(best_table[i], best_table_len[i], buf);
466 		printf("\t.asciz\t\"%s\"\n", buf);
467 		off += strlen(buf) + 1;
468 	}
469 	printf("\n");
470 
471 	output_label("kallsyms_token_index");
472 	for (i = 0; i < 256; i++)
473 		printf("\t.short\t%d\n", best_idx[i]);
474 	printf("\n");
475 }
476 
477 
478 /* table lookup compression functions */
479 
480 /* count all the possible tokens in a symbol */
481 static void learn_symbol(unsigned char *symbol, int len)
482 {
483 	int i;
484 
485 	for (i = 0; i < len - 1; i++)
486 		token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
487 }
488 
489 /* decrease the count for all the possible tokens in a symbol */
490 static void forget_symbol(unsigned char *symbol, int len)
491 {
492 	int i;
493 
494 	for (i = 0; i < len - 1; i++)
495 		token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
496 }
497 
498 /* remove all the invalid symbols from the table and do the initial token count */
499 static void build_initial_tok_table(void)
500 {
501 	unsigned int i, pos;
502 
503 	pos = 0;
504 	for (i = 0; i < table_cnt; i++) {
505 		if ( symbol_valid(&table[i]) ) {
506 			if (pos != i)
507 				table[pos] = table[i];
508 			learn_symbol(table[pos].sym, table[pos].len);
509 			pos++;
510 		}
511 	}
512 	table_cnt = pos;
513 }
514 
515 static void *find_token(unsigned char *str, int len, unsigned char *token)
516 {
517 	int i;
518 
519 	for (i = 0; i < len - 1; i++) {
520 		if (str[i] == token[0] && str[i+1] == token[1])
521 			return &str[i];
522 	}
523 	return NULL;
524 }
525 
526 /* replace a given token in all the valid symbols. Use the sampled symbols
527  * to update the counts */
528 static void compress_symbols(unsigned char *str, int idx)
529 {
530 	unsigned int i, len, size;
531 	unsigned char *p1, *p2;
532 
533 	for (i = 0; i < table_cnt; i++) {
534 
535 		len = table[i].len;
536 		p1 = table[i].sym;
537 
538 		/* find the token on the symbol */
539 		p2 = find_token(p1, len, str);
540 		if (!p2) continue;
541 
542 		/* decrease the counts for this symbol's tokens */
543 		forget_symbol(table[i].sym, len);
544 
545 		size = len;
546 
547 		do {
548 			*p2 = idx;
549 			p2++;
550 			size -= (p2 - p1);
551 			memmove(p2, p2 + 1, size);
552 			p1 = p2;
553 			len--;
554 
555 			if (size < 2) break;
556 
557 			/* find the token on the symbol */
558 			p2 = find_token(p1, size, str);
559 
560 		} while (p2);
561 
562 		table[i].len = len;
563 
564 		/* increase the counts for this symbol's new tokens */
565 		learn_symbol(table[i].sym, len);
566 	}
567 }
568 
569 /* search the token with the maximum profit */
570 static int find_best_token(void)
571 {
572 	int i, best, bestprofit;
573 
574 	bestprofit=-10000;
575 	best = 0;
576 
577 	for (i = 0; i < 0x10000; i++) {
578 		if (token_profit[i] > bestprofit) {
579 			best = i;
580 			bestprofit = token_profit[i];
581 		}
582 	}
583 	return best;
584 }
585 
586 /* this is the core of the algorithm: calculate the "best" table */
587 static void optimize_result(void)
588 {
589 	int i, best;
590 
591 	/* using the '\0' symbol last allows compress_symbols to use standard
592 	 * fast string functions */
593 	for (i = 255; i >= 0; i--) {
594 
595 		/* if this table slot is empty (it is not used by an actual
596 		 * original char code */
597 		if (!best_table_len[i]) {
598 
599 			/* find the token with the best profit value */
600 			best = find_best_token();
601 			if (token_profit[best] == 0)
602 				break;
603 
604 			/* place it in the "best" table */
605 			best_table_len[i] = 2;
606 			best_table[i][0] = best & 0xFF;
607 			best_table[i][1] = (best >> 8) & 0xFF;
608 
609 			/* replace this token in all the valid symbols */
610 			compress_symbols(best_table[i], i);
611 		}
612 	}
613 }
614 
615 /* start by placing the symbols that are actually used on the table */
616 static void insert_real_symbols_in_table(void)
617 {
618 	unsigned int i, j, c;
619 
620 	memset(best_table, 0, sizeof(best_table));
621 	memset(best_table_len, 0, sizeof(best_table_len));
622 
623 	for (i = 0; i < table_cnt; i++) {
624 		for (j = 0; j < table[i].len; j++) {
625 			c = table[i].sym[j];
626 			best_table[c][0]=c;
627 			best_table_len[c]=1;
628 		}
629 	}
630 }
631 
632 static void optimize_token_table(void)
633 {
634 	build_initial_tok_table();
635 
636 	insert_real_symbols_in_table();
637 
638 	/* When valid symbol is not registered, exit to error */
639 	if (!table_cnt) {
640 		fprintf(stderr, "No valid symbol.\n");
641 		exit(1);
642 	}
643 
644 	optimize_result();
645 }
646 
647 /* guess for "linker script provide" symbol */
648 static int may_be_linker_script_provide_symbol(const struct sym_entry *se)
649 {
650 	const char *symbol = (char *)se->sym + 1;
651 	int len = se->len - 1;
652 
653 	if (len < 8)
654 		return 0;
655 
656 	if (symbol[0] != '_' || symbol[1] != '_')
657 		return 0;
658 
659 	/* __start_XXXXX */
660 	if (!memcmp(symbol + 2, "start_", 6))
661 		return 1;
662 
663 	/* __stop_XXXXX */
664 	if (!memcmp(symbol + 2, "stop_", 5))
665 		return 1;
666 
667 	/* __end_XXXXX */
668 	if (!memcmp(symbol + 2, "end_", 4))
669 		return 1;
670 
671 	/* __XXXXX_start */
672 	if (!memcmp(symbol + len - 6, "_start", 6))
673 		return 1;
674 
675 	/* __XXXXX_end */
676 	if (!memcmp(symbol + len - 4, "_end", 4))
677 		return 1;
678 
679 	return 0;
680 }
681 
682 static int prefix_underscores_count(const char *str)
683 {
684 	const char *tail = str;
685 
686 	while (*tail == '_')
687 		tail++;
688 
689 	return tail - str;
690 }
691 
692 static int compare_symbols(const void *a, const void *b)
693 {
694 	const struct sym_entry *sa;
695 	const struct sym_entry *sb;
696 	int wa, wb;
697 
698 	sa = a;
699 	sb = b;
700 
701 	/* sort by address first */
702 	if (sa->addr > sb->addr)
703 		return 1;
704 	if (sa->addr < sb->addr)
705 		return -1;
706 
707 	/* sort by "weakness" type */
708 	wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
709 	wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
710 	if (wa != wb)
711 		return wa - wb;
712 
713 	/* sort by "linker script provide" type */
714 	wa = may_be_linker_script_provide_symbol(sa);
715 	wb = may_be_linker_script_provide_symbol(sb);
716 	if (wa != wb)
717 		return wa - wb;
718 
719 	/* sort by the number of prefix underscores */
720 	wa = prefix_underscores_count((const char *)sa->sym + 1);
721 	wb = prefix_underscores_count((const char *)sb->sym + 1);
722 	if (wa != wb)
723 		return wa - wb;
724 
725 	/* sort by initial order, so that other symbols are left undisturbed */
726 	return sa->start_pos - sb->start_pos;
727 }
728 
729 static void sort_symbols(void)
730 {
731 	qsort(table, table_cnt, sizeof(struct sym_entry), compare_symbols);
732 }
733 
734 static void make_percpus_absolute(void)
735 {
736 	unsigned int i;
737 
738 	for (i = 0; i < table_cnt; i++)
739 		if (symbol_in_range(&table[i], &percpu_range, 1)) {
740 			/*
741 			 * Keep the 'A' override for percpu symbols to
742 			 * ensure consistent behavior compared to older
743 			 * versions of this tool.
744 			 */
745 			table[i].sym[0] = 'A';
746 			table[i].percpu_absolute = 1;
747 		}
748 }
749 
750 /* find the minimum non-absolute symbol address */
751 static void record_relative_base(void)
752 {
753 	unsigned int i;
754 
755 	relative_base = -1ULL;
756 	for (i = 0; i < table_cnt; i++)
757 		if (!symbol_absolute(&table[i]) &&
758 		    table[i].addr < relative_base)
759 			relative_base = table[i].addr;
760 }
761 
762 int main(int argc, char **argv)
763 {
764 	if (argc >= 2) {
765 		int i;
766 		for (i = 1; i < argc; i++) {
767 			if(strcmp(argv[i], "--all-symbols") == 0)
768 				all_symbols = 1;
769 			else if (strcmp(argv[i], "--absolute-percpu") == 0)
770 				absolute_percpu = 1;
771 			else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) {
772 				char *p = &argv[i][16];
773 				/* skip quote */
774 				if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
775 					p++;
776 				symbol_prefix_char = *p;
777 			} else if (strcmp(argv[i], "--base-relative") == 0)
778 				base_relative = 1;
779 			else
780 				usage();
781 		}
782 	} else if (argc != 1)
783 		usage();
784 
785 	read_map(stdin);
786 	if (absolute_percpu)
787 		make_percpus_absolute();
788 	if (base_relative)
789 		record_relative_base();
790 	sort_symbols();
791 	optimize_token_table();
792 	write_src();
793 
794 	return 0;
795 }
796