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/* Generate assembler source containing symbol information * * Copyright 2002       by Kai Germaschewski * * This software may be used and distributed according to the terms * of the GNU General Public License, incorporated herein by reference. * * Usage: nm -n vmlinux | scripts/kallsyms [--all-symbols] > symbols.S * *      Table compression uses all the unused char codes on the symbols and *  maps these to the most used substrings (tokens). For instance, it might *  map char code 0xF7 to represent "write_" and then in every symbol where *  "write_" appears it can be replaced by 0xF7, saving 5 bytes. *      The used codes themselves are also placed in the table so that the *  decompresion can work without "special cases". *      Applied to kernel symbols, this usually produces a compression ratio *  of about 50%. * */ #include <stdio.h>#include <stdlib.h>#include <string.h>#include <ctype.h>#include <limits.h> #ifndef ARRAY_SIZE#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))#endif #define KSYM_NAME_LEN		128 struct sym_entry {	unsigned long long addr;	unsigned int len;	unsigned int start_pos;	unsigned char *sym;	unsigned int percpu_absolute;}; struct addr_range {	const char *start_sym, *end_sym;	unsigned long long start, end;}; static unsigned long long _text;static unsigned long long relative_base;static struct addr_range text_ranges[] = {	{ "_stext",     "_etext"     },	{ "_sinittext", "_einittext" },	{ "_stext_l1",  "_etext_l1"  },	/* Blackfin on-chip L1 inst SRAM */	{ "_stext_l2",  "_etext_l2"  },	/* Blackfin on-chip L2 SRAM */};#define text_range_text     (&text_ranges[0])#define text_range_inittext (&text_ranges[1]) static struct addr_range percpu_range = {	"__per_cpu_start", "__per_cpu_end", -1ULL, 0}; static struct sym_entry *table;static unsigned int table_size, table_cnt;static int all_symbols = 0;static int absolute_percpu = 0;static char symbol_prefix_char = '\0';static int base_relative = 0; int token_profit[0x10000]; /* the table that holds the result of the compression */unsigned char best_table[256][2];unsigned char best_table_len[256];  static void usage(void){	fprintf(stderr, "Usage: kallsyms [--all-symbols] "			"[--symbol-prefix=<prefix char>] "			"[--base-relative] < in.map > out.S\n");	exit(1);} /* * This ignores the intensely annoying "mapping symbols" found * in ARM ELF files: $a, $t and $d. */static inline int is_arm_mapping_symbol(const char *str){	return str[0] == '$' && strchr("axtd", str[1])	       && (str[2] == '\0' || str[2] == '.');} static int check_symbol_range(const char *sym, unsigned long long addr,			      struct addr_range *ranges, int entries){	size_t i;	struct addr_range *ar; 	for (i = 0; i < entries; ++i) {		ar = &ranges[i]; 		if (strcmp(sym, ar->start_sym) == 0) {			ar->start = addr;			return 0;		} else if (strcmp(sym, ar->end_sym) == 0) {			ar->end = addr;			return 0;		}	} 	return 1;} static int read_symbol(FILE *in, struct sym_entry *s){	char str[500];	char *sym, stype;	int rc; 	rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str);	if (rc != 3) {		if (rc != EOF && fgets(str, 500, in) == NULL)			fprintf(stderr, "Read error or end of file.\n");		return -1;	}	if (strlen(str) > KSYM_NAME_LEN) {		fprintf(stderr, "Symbol %s too long for kallsyms (%zu vs %d).\n"				"Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",			str, strlen(str), KSYM_NAME_LEN);		return -1;	} 	sym = str;	/* skip prefix char */	if (symbol_prefix_char && str[0] == symbol_prefix_char)		sym++; 	/* Ignore most absolute/undefined (?) symbols. */	if (strcmp(sym, "_text") == 0)		_text = s->addr;	else if (check_symbol_range(sym, s->addr, text_ranges,				    ARRAY_SIZE(text_ranges)) == 0)		/* nothing to do */;	else if (toupper(stype) == 'A')	{		/* Keep these useful absolute symbols */		if (strcmp(sym, "__kernel_syscall_via_break") &&		    strcmp(sym, "__kernel_syscall_via_epc") &&		    strcmp(sym, "__kernel_sigtramp") &&		    strcmp(sym, "__gp"))			return -1; 	}	else if (toupper(stype) == 'U' ||		 is_arm_mapping_symbol(sym))		return -1;	/* exclude also MIPS ELF local symbols ($L123 instead of .L123) */	else if (str[0] == '$')		return -1;	/* exclude debugging symbols */	else if (stype == 'N')		return -1; 	/* include the type field in the symbol name, so that it gets	 * compressed together */	s->len = strlen(str) + 1;	s->sym = malloc(s->len + 1);	if (!s->sym) {		fprintf(stderr, "kallsyms failure: "			"unable to allocate required amount of memory\n");		exit(EXIT_FAILURE);	}	strcpy((char *)s->sym + 1, str);	s->sym[0] = stype; 	s->percpu_absolute = 0; 	/* Record if we've found __per_cpu_start/end. */	check_symbol_range(sym, s->addr, &percpu_range, 1); 	return 0;} static int symbol_in_range(struct sym_entry *s, struct addr_range *ranges,			   int entries){	size_t i;	struct addr_range *ar; 	for (i = 0; i < entries; ++i) {		ar = &ranges[i]; 		if (s->addr >= ar->start && s->addr <= ar->end)			return 1;	} 	return 0;} static int symbol_valid(struct sym_entry *s){	/* Symbols which vary between passes.  Passes 1 and 2 must have	 * identical symbol lists.  The kallsyms_* symbols below are only added	 * after pass 1, they would be included in pass 2 when --all-symbols is	 * specified so exclude them to get a stable symbol list.	 */	static char *special_symbols[] = {		"kallsyms_addresses",		"kallsyms_offsets",		"kallsyms_relative_base",		"kallsyms_num_syms",		"kallsyms_names",		"kallsyms_markers",		"kallsyms_token_table",		"kallsyms_token_index", 	/* Exclude linker generated symbols which vary between passes */		"_SDA_BASE_",		/* ppc */		"_SDA2_BASE_",		/* ppc */		NULL }; 	static char *special_prefixes[] = {		"__crc_",		/* modversions */		NULL }; 	static char *special_suffixes[] = {		"_veneer",		/* arm */		"_from_arm",		/* arm */		"_from_thumb",		/* arm */		NULL }; 	int i;	char *sym_name = (char *)s->sym + 1; 	/* skip prefix char */	if (symbol_prefix_char && *sym_name == symbol_prefix_char)		sym_name++;  	/* if --all-symbols is not specified, then symbols outside the text	 * and inittext sections are discarded */	if (!all_symbols) {		if (symbol_in_range(s, text_ranges,				    ARRAY_SIZE(text_ranges)) == 0)			return 0;		/* Corner case.  Discard any symbols with the same value as		 * _etext _einittext; they can move between pass 1 and 2 when		 * the kallsyms data are added.  If these symbols move then		 * they may get dropped in pass 2, which breaks the kallsyms		 * rules.		 */		if ((s->addr == text_range_text->end &&				strcmp(sym_name,				       text_range_text->end_sym)) ||		    (s->addr == text_range_inittext->end &&				strcmp(sym_name,				       text_range_inittext->end_sym)))			return 0;	} 	/* Exclude symbols which vary between passes. */	for (i = 0; special_symbols[i]; i++)		if (strcmp(sym_name, special_symbols[i]) == 0)			return 0; 	for (i = 0; special_prefixes[i]; i++) {		int l = strlen(special_prefixes[i]); 		if (l <= strlen(sym_name) &&		    strncmp(sym_name, special_prefixes[i], l) == 0)			return 0;	} 	for (i = 0; special_suffixes[i]; i++) {		int l = strlen(sym_name) - strlen(special_suffixes[i]); 		if (l >= 0 && strcmp(sym_name + l, special_suffixes[i]) == 0)			return 0;	} 	return 1;} static void read_map(FILE *in){	while (!feof(in)) {		if (table_cnt >= table_size) {			table_size += 10000;			table = realloc(table, sizeof(*table) * table_size);			if (!table) {				fprintf(stderr, "out of memory\n");				exit (1);			}		}		if (read_symbol(in, &table[table_cnt]) == 0) {			table[table_cnt].start_pos = table_cnt;			table_cnt++;		}	}} static void output_label(char *label){	if (symbol_prefix_char)		printf(".globl %c%s\n", symbol_prefix_char, label);	else		printf(".globl %s\n", label);	printf("\tALGN\n");	if (symbol_prefix_char)		printf("%c%s:\n", symbol_prefix_char, label);	else		printf("%s:\n", label);} /* uncompress a compressed symbol. When this function is called, the best table * might still be compressed itself, so the function needs to be recursive */static int expand_symbol(unsigned char *data, int len, char *result){	int c, rlen, total=0; 	while (len) {		c = *data;		/* if the table holds a single char that is the same as the one		 * we are looking for, then end the search */		if (best_table[c][0]==c && best_table_len[c]==1) {			*result++ = c;			total++;		} else {			/* if not, recurse and expand */			rlen = expand_symbol(best_table[c], best_table_len[c], result);			total += rlen;			result += rlen;		}		data++;		len--;	}	*result=0; 	return total;} static int symbol_absolute(struct sym_entry *s){	return s->percpu_absolute;} static void write_src(void){	unsigned int i, k, off;	unsigned int best_idx[256];	unsigned int *markers;	char buf[KSYM_NAME_LEN]; 	printf("#include <asm/types.h>\n");	printf("#if BITS_PER_LONG == 64\n");	printf("#define PTR .quad\n");	printf("#define ALGN .align 8\n");	printf("#else\n");	printf("#define PTR .long\n");	printf("#define ALGN .align 4\n");	printf("#endif\n"); 	printf("\t.section .rodata, \"a\"\n"); 	/* Provide proper symbols relocatability by their relativeness	 * to a fixed anchor point in the runtime image, either '_text'	 * for absolute address tables, in which case the linker will	 * emit the final addresses at build time. Otherwise, use the	 * offset relative to the lowest value encountered of all relative	 * symbols, and emit non-relocatable fixed offsets that will be fixed	 * up at runtime.	 *	 * The symbol names cannot be used to construct normal symbol	 * references as the list of symbols contains symbols that are	 * declared static and are private to their .o files.  This prevents	 * .tmp_kallsyms.o or any other object from referencing them.	 */	if (!base_relative)		output_label("kallsyms_addresses");	else		output_label("kallsyms_offsets"); 	for (i = 0; i < table_cnt; i++) {		if (base_relative) {			long long offset;			int overflow; 			if (!absolute_percpu) {				offset = table[i].addr - relative_base;				overflow = (offset < 0 || offset > UINT_MAX);			} else if (symbol_absolute(&table[i])) {				offset = table[i].addr;				overflow = (offset < 0 || offset > INT_MAX);			} else {				offset = relative_base - table[i].addr - 1;				overflow = (offset < INT_MIN || offset >= 0);			}			if (overflow) {				fprintf(stderr, "kallsyms failure: "					"%s symbol value %#llx out of range in relative mode\n",					symbol_absolute(&table[i]) ? "absolute" : "relative",					table[i].addr);				exit(EXIT_FAILURE);			}			printf("\t.long\t%#x\n", (int)offset);		} else if (!symbol_absolute(&table[i])) {			if (_text <= table[i].addr)				printf("\tPTR\t_text + %#llx\n",					table[i].addr - _text);			else				printf("\tPTR\t_text - %#llx\n",					_text - table[i].addr);		} else {			printf("\tPTR\t%#llx\n", table[i].addr);		}	}	printf("\n"); 	if (base_relative) {		output_label("kallsyms_relative_base");		printf("\tPTR\t_text - %#llx\n", _text - relative_base);		printf("\n");	} 	output_label("kallsyms_num_syms");	printf("\tPTR\t%d\n", table_cnt);	printf("\n"); 	/* table of offset markers, that give the offset in the compressed stream	 * every 256 symbols */	markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));	if (!markers) {		fprintf(stderr, "kallsyms failure: "			"unable to allocate required memory\n");		exit(EXIT_FAILURE);	} 	output_label("kallsyms_names");	off = 0;	for (i = 0; i < table_cnt; i++) {		if ((i & 0xFF) == 0)			markers[i >> 8] = off; 		printf("\t.byte 0x%02x", table[i].len);		for (k = 0; k < table[i].len; k++)			printf(", 0x%02x", table[i].sym[k]);		printf("\n"); 		off += table[i].len + 1;	}	printf("\n"); 	output_label("kallsyms_markers");	for (i = 0; i < ((table_cnt + 255) >> 8); i++)		printf("\tPTR\t%d\n", markers[i]);	printf("\n"); 	free(markers); 	output_label("kallsyms_token_table");	off = 0;	for (i = 0; i < 256; i++) {		best_idx[i] = off;		expand_symbol(best_table[i], best_table_len[i], buf);		printf("\t.asciz\t\"%s\"\n", buf);		off += strlen(buf) + 1;	}	printf("\n"); 	output_label("kallsyms_token_index");	for (i = 0; i < 256; i++)		printf("\t.short\t%d\n", best_idx[i]);	printf("\n");}  /* table lookup compression functions */ /* count all the possible tokens in a symbol */static void learn_symbol(unsigned char *symbol, int len){	int i; 	for (i = 0; i < len - 1; i++)		token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;} /* decrease the count for all the possible tokens in a symbol */static void forget_symbol(unsigned char *symbol, int len){	int i; 	for (i = 0; i < len - 1; i++)		token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;} /* remove all the invalid symbols from the table and do the initial token count */static void build_initial_tok_table(void){	unsigned int i, pos;

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