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v5.9
  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}
v6.2
  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] 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
 50struct 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
 59struct addr_range {
 60	const char *start_sym, *end_sym;
 61	unsigned long long start, end;
 62};
 63
 64static unsigned long long _text;
 65static unsigned long long relative_base;
 66static 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
 73static struct addr_range percpu_range = {
 74	"__per_cpu_start", "__per_cpu_end", -1ULL, 0
 75};
 76
 77static struct sym_entry **table;
 78static unsigned int table_size, table_cnt;
 79static int all_symbols;
 80static int absolute_percpu;
 81static int base_relative;
 82static int lto_clang;
 83
 84static int token_profit[0x10000];
 85
 86/* the table that holds the result of the compression */
 87static unsigned char best_table[256][2];
 88static unsigned char best_table_len[256];
 89
 90
 91static 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
 98static char *sym_name(const struct sym_entry *s)
 99{
100	return (char *)s->sym + 1;
101}
102
103static 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		/* Exclude linker generated symbols which vary between passes */
123		"_SDA_BASE_",		/* ppc */
124		"_SDA2_BASE_",		/* ppc */
125		NULL
126	};
127
128	/* Symbol names that begin with the following are ignored.*/
129	static const char * const ignored_prefixes[] = {
 
 
 
130		"__efistub_",		/* arm64 EFI stub namespace */
131		"__kvm_nvhe_$",		/* arm64 local symbols in non-VHE KVM namespace */
132		"__kvm_nvhe_.L",	/* arm64 local symbols in non-VHE KVM namespace */
133		"__AArch64ADRPThunk_",	/* arm64 lld */
134		"__ARMV5PILongThunk_",	/* arm lld */
135		"__ARMV7PILongThunk_",
136		"__ThumbV7PILongThunk_",
137		"__LA25Thunk_",		/* mips lld */
138		"__microLA25Thunk_",
139		"__kcfi_typeid_",	/* CFI type identifiers */
140		NULL
141	};
142
143	/* Symbol names that end with the following are ignored.*/
144	static const char * const ignored_suffixes[] = {
145		"_from_arm",		/* arm */
146		"_from_thumb",		/* arm */
147		"_veneer",		/* arm */
148		NULL
149	};
150
151	/* Symbol names that contain the following are ignored.*/
152	static const char * const ignored_matches[] = {
153		".long_branch.",	/* ppc stub */
154		".plt_branch.",		/* ppc stub */
155		NULL
156	};
157
158	const char * const *p;
159
160	for (p = ignored_symbols; *p; p++)
161		if (!strcmp(name, *p))
162			return true;
163
164	for (p = ignored_prefixes; *p; p++)
165		if (!strncmp(name, *p, strlen(*p)))
166			return true;
167
168	for (p = ignored_suffixes; *p; p++) {
169		int l = strlen(name) - strlen(*p);
170
171		if (l >= 0 && !strcmp(name + l, *p))
172			return true;
173	}
174
175	for (p = ignored_matches; *p; p++) {
176		if (strstr(name, *p))
177			return true;
178	}
179
180	if (type == 'U' || type == 'u')
181		return true;
182	/* exclude debugging symbols */
183	if (type == 'N' || type == 'n')
184		return true;
185
186	if (toupper(type) == 'A') {
187		/* Keep these useful absolute symbols */
188		if (strcmp(name, "__kernel_syscall_via_break") &&
189		    strcmp(name, "__kernel_syscall_via_epc") &&
190		    strcmp(name, "__kernel_sigtramp") &&
191		    strcmp(name, "__gp"))
192			return true;
193	}
194
195	return false;
196}
197
198static void check_symbol_range(const char *sym, unsigned long long addr,
199			       struct addr_range *ranges, int entries)
200{
201	size_t i;
202	struct addr_range *ar;
203
204	for (i = 0; i < entries; ++i) {
205		ar = &ranges[i];
206
207		if (strcmp(sym, ar->start_sym) == 0) {
208			ar->start = addr;
209			return;
210		} else if (strcmp(sym, ar->end_sym) == 0) {
211			ar->end = addr;
212			return;
213		}
214	}
215}
216
217static struct sym_entry *read_symbol(FILE *in)
218{
219	char name[KSYM_NAME_LEN_BUFFER+1], type;
220	unsigned long long addr;
221	unsigned int len;
222	struct sym_entry *sym;
223	int rc;
224
225	rc = fscanf(in, "%llx %c %" _stringify(KSYM_NAME_LEN_BUFFER) "s\n", &addr, &type, name);
226	if (rc != 3) {
227		if (rc != EOF && fgets(name, ARRAY_SIZE(name), in) == NULL)
228			fprintf(stderr, "Read error or end of file.\n");
229		return NULL;
230	}
231	if (strlen(name) >= KSYM_NAME_LEN) {
232		fprintf(stderr, "Symbol %s too long for kallsyms (%zu >= %d).\n"
233				"Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",
234			name, strlen(name), KSYM_NAME_LEN);
235		return NULL;
236	}
237
238	if (strcmp(name, "_text") == 0)
239		_text = addr;
240
241	/* Ignore most absolute/undefined (?) symbols. */
242	if (is_ignored_symbol(name, type))
243		return NULL;
244
245	check_symbol_range(name, addr, text_ranges, ARRAY_SIZE(text_ranges));
246	check_symbol_range(name, addr, &percpu_range, 1);
247
248	/* include the type field in the symbol name, so that it gets
249	 * compressed together */
250
251	len = strlen(name) + 1;
252
253	sym = malloc(sizeof(*sym) + len + 1);
254	if (!sym) {
255		fprintf(stderr, "kallsyms failure: "
256			"unable to allocate required amount of memory\n");
257		exit(EXIT_FAILURE);
258	}
259	sym->addr = addr;
260	sym->len = len;
261	sym->sym[0] = type;
262	strcpy(sym_name(sym), name);
263	sym->percpu_absolute = 0;
264
265	return sym;
266}
267
268static int symbol_in_range(const struct sym_entry *s,
269			   const struct addr_range *ranges, int entries)
270{
271	size_t i;
272	const struct addr_range *ar;
273
274	for (i = 0; i < entries; ++i) {
275		ar = &ranges[i];
276
277		if (s->addr >= ar->start && s->addr <= ar->end)
278			return 1;
279	}
280
281	return 0;
282}
283
284static int symbol_valid(const struct sym_entry *s)
285{
286	const char *name = sym_name(s);
287
288	/* if --all-symbols is not specified, then symbols outside the text
289	 * and inittext sections are discarded */
290	if (!all_symbols) {
291		if (symbol_in_range(s, text_ranges,
292				    ARRAY_SIZE(text_ranges)) == 0)
293			return 0;
294		/* Corner case.  Discard any symbols with the same value as
295		 * _etext _einittext; they can move between pass 1 and 2 when
296		 * the kallsyms data are added.  If these symbols move then
297		 * they may get dropped in pass 2, which breaks the kallsyms
298		 * rules.
299		 */
300		if ((s->addr == text_range_text->end &&
301		     strcmp(name, text_range_text->end_sym)) ||
302		    (s->addr == text_range_inittext->end &&
303		     strcmp(name, text_range_inittext->end_sym)))
304			return 0;
305	}
306
307	return 1;
308}
309
310/* remove all the invalid symbols from the table */
311static void shrink_table(void)
312{
313	unsigned int i, pos;
314
315	pos = 0;
316	for (i = 0; i < table_cnt; i++) {
317		if (symbol_valid(table[i])) {
318			if (pos != i)
319				table[pos] = table[i];
320			pos++;
321		} else {
322			free(table[i]);
323		}
324	}
325	table_cnt = pos;
326
327	/* When valid symbol is not registered, exit to error */
328	if (!table_cnt) {
329		fprintf(stderr, "No valid symbol.\n");
330		exit(1);
331	}
332}
333
334static void read_map(const char *in)
335{
336	FILE *fp;
337	struct sym_entry *sym;
338
339	fp = fopen(in, "r");
340	if (!fp) {
341		perror(in);
342		exit(1);
343	}
344
345	while (!feof(fp)) {
346		sym = read_symbol(fp);
347		if (!sym)
348			continue;
349
350		sym->start_pos = table_cnt;
351
352		if (table_cnt >= table_size) {
353			table_size += 10000;
354			table = realloc(table, sizeof(*table) * table_size);
355			if (!table) {
356				fprintf(stderr, "out of memory\n");
357				fclose(fp);
358				exit (1);
359			}
360		}
361
362		table[table_cnt++] = sym;
363	}
364
365	fclose(fp);
366}
367
368static void output_label(const char *label)
369{
370	printf(".globl %s\n", label);
371	printf("\tALGN\n");
372	printf("%s:\n", label);
373}
374
375/* Provide proper symbols relocatability by their '_text' relativeness. */
376static void output_address(unsigned long long addr)
377{
378	if (_text <= addr)
379		printf("\tPTR\t_text + %#llx\n", addr - _text);
380	else
381		printf("\tPTR\t_text - %#llx\n", _text - addr);
382}
383
384/* uncompress a compressed symbol. When this function is called, the best table
385 * might still be compressed itself, so the function needs to be recursive */
386static int expand_symbol(const unsigned char *data, int len, char *result)
387{
388	int c, rlen, total=0;
389
390	while (len) {
391		c = *data;
392		/* if the table holds a single char that is the same as the one
393		 * we are looking for, then end the search */
394		if (best_table[c][0]==c && best_table_len[c]==1) {
395			*result++ = c;
396			total++;
397		} else {
398			/* if not, recurse and expand */
399			rlen = expand_symbol(best_table[c], best_table_len[c], result);
400			total += rlen;
401			result += rlen;
402		}
403		data++;
404		len--;
405	}
406	*result=0;
407
408	return total;
409}
410
411static int symbol_absolute(const struct sym_entry *s)
412{
413	return s->percpu_absolute;
414}
415
416static char * s_name(char *buf)
417{
418	/* Skip the symbol type */
419	return buf + 1;
420}
421
422static void cleanup_symbol_name(char *s)
423{
424	char *p;
425
426	if (!lto_clang)
427		return;
428
429	/*
430	 * ASCII[.]   = 2e
431	 * ASCII[0-9] = 30,39
432	 * ASCII[A-Z] = 41,5a
433	 * ASCII[_]   = 5f
434	 * ASCII[a-z] = 61,7a
435	 *
436	 * As above, replacing '.' with '\0' does not affect the main sorting,
437	 * but it helps us with subsorting.
438	 */
439	p = strchr(s, '.');
440	if (p)
441		*p = '\0';
442}
443
444static int compare_names(const void *a, const void *b)
445{
446	int ret;
447	char sa_namebuf[KSYM_NAME_LEN];
448	char sb_namebuf[KSYM_NAME_LEN];
449	const struct sym_entry *sa = *(const struct sym_entry **)a;
450	const struct sym_entry *sb = *(const struct sym_entry **)b;
451
452	expand_symbol(sa->sym, sa->len, sa_namebuf);
453	expand_symbol(sb->sym, sb->len, sb_namebuf);
454	cleanup_symbol_name(s_name(sa_namebuf));
455	cleanup_symbol_name(s_name(sb_namebuf));
456	ret = strcmp(s_name(sa_namebuf), s_name(sb_namebuf));
457	if (!ret) {
458		if (sa->addr > sb->addr)
459			return 1;
460		else if (sa->addr < sb->addr)
461			return -1;
462
463		/* keep old order */
464		return (int)(sa->seq - sb->seq);
465	}
466
467	return ret;
468}
469
470static void sort_symbols_by_name(void)
471{
472	qsort(table, table_cnt, sizeof(table[0]), compare_names);
473}
474
475static void write_src(void)
476{
477	unsigned int i, k, off;
478	unsigned int best_idx[256];
479	unsigned int *markers;
480	char buf[KSYM_NAME_LEN];
481
482	printf("#include <asm/bitsperlong.h>\n");
483	printf("#if BITS_PER_LONG == 64\n");
484	printf("#define PTR .quad\n");
485	printf("#define ALGN .balign 8\n");
486	printf("#else\n");
487	printf("#define PTR .long\n");
488	printf("#define ALGN .balign 4\n");
489	printf("#endif\n");
490
491	printf("\t.section .rodata, \"a\"\n");
492
493	if (!base_relative)
494		output_label("kallsyms_addresses");
495	else
496		output_label("kallsyms_offsets");
497
498	for (i = 0; i < table_cnt; i++) {
499		if (base_relative) {
500			/*
501			 * Use the offset relative to the lowest value
502			 * encountered of all relative symbols, and emit
503			 * non-relocatable fixed offsets that will be fixed
504			 * up at runtime.
505			 */
506
507			long long offset;
508			int overflow;
509
510			if (!absolute_percpu) {
511				offset = table[i]->addr - relative_base;
512				overflow = (offset < 0 || offset > UINT_MAX);
513			} else if (symbol_absolute(table[i])) {
514				offset = table[i]->addr;
515				overflow = (offset < 0 || offset > INT_MAX);
516			} else {
517				offset = relative_base - table[i]->addr - 1;
518				overflow = (offset < INT_MIN || offset >= 0);
519			}
520			if (overflow) {
521				fprintf(stderr, "kallsyms failure: "
522					"%s symbol value %#llx out of range in relative mode\n",
523					symbol_absolute(table[i]) ? "absolute" : "relative",
524					table[i]->addr);
525				exit(EXIT_FAILURE);
526			}
527			printf("\t.long\t%#x\n", (int)offset);
528		} else if (!symbol_absolute(table[i])) {
529			output_address(table[i]->addr);
530		} else {
531			printf("\tPTR\t%#llx\n", table[i]->addr);
532		}
533	}
534	printf("\n");
535
536	if (base_relative) {
537		output_label("kallsyms_relative_base");
538		output_address(relative_base);
539		printf("\n");
540	}
541
542	output_label("kallsyms_num_syms");
543	printf("\t.long\t%u\n", table_cnt);
544	printf("\n");
545
546	/* table of offset markers, that give the offset in the compressed stream
547	 * every 256 symbols */
548	markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
549	if (!markers) {
550		fprintf(stderr, "kallsyms failure: "
551			"unable to allocate required memory\n");
552		exit(EXIT_FAILURE);
553	}
554
555	output_label("kallsyms_names");
556	off = 0;
557	for (i = 0; i < table_cnt; i++) {
558		if ((i & 0xFF) == 0)
559			markers[i >> 8] = off;
560		table[i]->seq = i;
561
562		/* There cannot be any symbol of length zero. */
563		if (table[i]->len == 0) {
564			fprintf(stderr, "kallsyms failure: "
565				"unexpected zero symbol length\n");
566			exit(EXIT_FAILURE);
567		}
568
569		/* Only lengths that fit in up-to-two-byte ULEB128 are supported. */
570		if (table[i]->len > 0x3FFF) {
571			fprintf(stderr, "kallsyms failure: "
572				"unexpected huge symbol length\n");
573			exit(EXIT_FAILURE);
574		}
575
576		/* Encode length with ULEB128. */
577		if (table[i]->len <= 0x7F) {
578			/* Most symbols use a single byte for the length. */
579			printf("\t.byte 0x%02x", table[i]->len);
580			off += table[i]->len + 1;
581		} else {
582			/* "Big" symbols use two bytes. */
583			printf("\t.byte 0x%02x, 0x%02x",
584				(table[i]->len & 0x7F) | 0x80,
585				(table[i]->len >> 7) & 0x7F);
586			off += table[i]->len + 2;
587		}
588		for (k = 0; k < table[i]->len; k++)
589			printf(", 0x%02x", table[i]->sym[k]);
590		printf("\n");
 
 
591	}
592	printf("\n");
593
594	output_label("kallsyms_markers");
595	for (i = 0; i < ((table_cnt + 255) >> 8); i++)
596		printf("\t.long\t%u\n", markers[i]);
597	printf("\n");
598
599	free(markers);
600
601	sort_symbols_by_name();
602	output_label("kallsyms_seqs_of_names");
603	for (i = 0; i < table_cnt; i++)
604		printf("\t.byte 0x%02x, 0x%02x, 0x%02x\n",
605			(unsigned char)(table[i]->seq >> 16),
606			(unsigned char)(table[i]->seq >> 8),
607			(unsigned char)(table[i]->seq >> 0));
608	printf("\n");
609
610	output_label("kallsyms_token_table");
611	off = 0;
612	for (i = 0; i < 256; i++) {
613		best_idx[i] = off;
614		expand_symbol(best_table[i], best_table_len[i], buf);
615		printf("\t.asciz\t\"%s\"\n", buf);
616		off += strlen(buf) + 1;
617	}
618	printf("\n");
619
620	output_label("kallsyms_token_index");
621	for (i = 0; i < 256; i++)
622		printf("\t.short\t%d\n", best_idx[i]);
623	printf("\n");
624}
625
626
627/* table lookup compression functions */
628
629/* count all the possible tokens in a symbol */
630static void learn_symbol(const unsigned char *symbol, int len)
631{
632	int i;
633
634	for (i = 0; i < len - 1; i++)
635		token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
636}
637
638/* decrease the count for all the possible tokens in a symbol */
639static void forget_symbol(const unsigned char *symbol, int len)
640{
641	int i;
642
643	for (i = 0; i < len - 1; i++)
644		token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
645}
646
647/* do the initial token count */
648static void build_initial_token_table(void)
649{
650	unsigned int i;
651
652	for (i = 0; i < table_cnt; i++)
653		learn_symbol(table[i]->sym, table[i]->len);
654}
655
656static unsigned char *find_token(unsigned char *str, int len,
657				 const unsigned char *token)
658{
659	int i;
660
661	for (i = 0; i < len - 1; i++) {
662		if (str[i] == token[0] && str[i+1] == token[1])
663			return &str[i];
664	}
665	return NULL;
666}
667
668/* replace a given token in all the valid symbols. Use the sampled symbols
669 * to update the counts */
670static void compress_symbols(const unsigned char *str, int idx)
671{
672	unsigned int i, len, size;
673	unsigned char *p1, *p2;
674
675	for (i = 0; i < table_cnt; i++) {
676
677		len = table[i]->len;
678		p1 = table[i]->sym;
679
680		/* find the token on the symbol */
681		p2 = find_token(p1, len, str);
682		if (!p2) continue;
683
684		/* decrease the counts for this symbol's tokens */
685		forget_symbol(table[i]->sym, len);
686
687		size = len;
688
689		do {
690			*p2 = idx;
691			p2++;
692			size -= (p2 - p1);
693			memmove(p2, p2 + 1, size);
694			p1 = p2;
695			len--;
696
697			if (size < 2) break;
698
699			/* find the token on the symbol */
700			p2 = find_token(p1, size, str);
701
702		} while (p2);
703
704		table[i]->len = len;
705
706		/* increase the counts for this symbol's new tokens */
707		learn_symbol(table[i]->sym, len);
708	}
709}
710
711/* search the token with the maximum profit */
712static int find_best_token(void)
713{
714	int i, best, bestprofit;
715
716	bestprofit=-10000;
717	best = 0;
718
719	for (i = 0; i < 0x10000; i++) {
720		if (token_profit[i] > bestprofit) {
721			best = i;
722			bestprofit = token_profit[i];
723		}
724	}
725	return best;
726}
727
728/* this is the core of the algorithm: calculate the "best" table */
729static void optimize_result(void)
730{
731	int i, best;
732
733	/* using the '\0' symbol last allows compress_symbols to use standard
734	 * fast string functions */
735	for (i = 255; i >= 0; i--) {
736
737		/* if this table slot is empty (it is not used by an actual
738		 * original char code */
739		if (!best_table_len[i]) {
740
741			/* find the token with the best profit value */
742			best = find_best_token();
743			if (token_profit[best] == 0)
744				break;
745
746			/* place it in the "best" table */
747			best_table_len[i] = 2;
748			best_table[i][0] = best & 0xFF;
749			best_table[i][1] = (best >> 8) & 0xFF;
750
751			/* replace this token in all the valid symbols */
752			compress_symbols(best_table[i], i);
753		}
754	}
755}
756
757/* start by placing the symbols that are actually used on the table */
758static void insert_real_symbols_in_table(void)
759{
760	unsigned int i, j, c;
761
762	for (i = 0; i < table_cnt; i++) {
763		for (j = 0; j < table[i]->len; j++) {
764			c = table[i]->sym[j];
765			best_table[c][0]=c;
766			best_table_len[c]=1;
767		}
768	}
769}
770
771static void optimize_token_table(void)
772{
773	build_initial_token_table();
774
775	insert_real_symbols_in_table();
776
777	optimize_result();
778}
779
780/* guess for "linker script provide" symbol */
781static int may_be_linker_script_provide_symbol(const struct sym_entry *se)
782{
783	const char *symbol = sym_name(se);
784	int len = se->len - 1;
785
786	if (len < 8)
787		return 0;
788
789	if (symbol[0] != '_' || symbol[1] != '_')
790		return 0;
791
792	/* __start_XXXXX */
793	if (!memcmp(symbol + 2, "start_", 6))
794		return 1;
795
796	/* __stop_XXXXX */
797	if (!memcmp(symbol + 2, "stop_", 5))
798		return 1;
799
800	/* __end_XXXXX */
801	if (!memcmp(symbol + 2, "end_", 4))
802		return 1;
803
804	/* __XXXXX_start */
805	if (!memcmp(symbol + len - 6, "_start", 6))
806		return 1;
807
808	/* __XXXXX_end */
809	if (!memcmp(symbol + len - 4, "_end", 4))
810		return 1;
811
812	return 0;
813}
814
815static int compare_symbols(const void *a, const void *b)
816{
817	const struct sym_entry *sa = *(const struct sym_entry **)a;
818	const struct sym_entry *sb = *(const struct sym_entry **)b;
819	int wa, wb;
820
821	/* sort by address first */
822	if (sa->addr > sb->addr)
823		return 1;
824	if (sa->addr < sb->addr)
825		return -1;
826
827	/* sort by "weakness" type */
828	wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
829	wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
830	if (wa != wb)
831		return wa - wb;
832
833	/* sort by "linker script provide" type */
834	wa = may_be_linker_script_provide_symbol(sa);
835	wb = may_be_linker_script_provide_symbol(sb);
836	if (wa != wb)
837		return wa - wb;
838
839	/* sort by the number of prefix underscores */
840	wa = strspn(sym_name(sa), "_");
841	wb = strspn(sym_name(sb), "_");
842	if (wa != wb)
843		return wa - wb;
844
845	/* sort by initial order, so that other symbols are left undisturbed */
846	return sa->start_pos - sb->start_pos;
847}
848
849static void sort_symbols(void)
850{
851	qsort(table, table_cnt, sizeof(table[0]), compare_symbols);
852}
853
854static void make_percpus_absolute(void)
855{
856	unsigned int i;
857
858	for (i = 0; i < table_cnt; i++)
859		if (symbol_in_range(table[i], &percpu_range, 1)) {
860			/*
861			 * Keep the 'A' override for percpu symbols to
862			 * ensure consistent behavior compared to older
863			 * versions of this tool.
864			 */
865			table[i]->sym[0] = 'A';
866			table[i]->percpu_absolute = 1;
867		}
868}
869
870/* find the minimum non-absolute symbol address */
871static void record_relative_base(void)
872{
873	unsigned int i;
874
875	for (i = 0; i < table_cnt; i++)
876		if (!symbol_absolute(table[i])) {
877			/*
878			 * The table is sorted by address.
879			 * Take the first non-absolute symbol value.
880			 */
881			relative_base = table[i]->addr;
882			return;
883		}
884}
885
886int main(int argc, char **argv)
887{
888	while (1) {
889		static struct option long_options[] = {
890			{"all-symbols",     no_argument, &all_symbols,     1},
891			{"absolute-percpu", no_argument, &absolute_percpu, 1},
892			{"base-relative",   no_argument, &base_relative,   1},
893			{"lto-clang",       no_argument, &lto_clang,       1},
894			{},
895		};
896
897		int c = getopt_long(argc, argv, "", long_options, NULL);
898
899		if (c == -1)
900			break;
901		if (c != 0)
902			usage();
903	}
904
905	if (optind >= argc)
906		usage();
907
908	read_map(argv[optind]);
909	shrink_table();
910	if (absolute_percpu)
911		make_percpus_absolute();
912	sort_symbols();
913	if (base_relative)
914		record_relative_base();
915	optimize_token_table();
916	write_src();
917
918	return 0;
919}