scripts/kallsyms.c - kernel/msm-4.19 - Gitiles

 /* 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
  *
  * ChangeLog:
  *
  * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
  *      Changed the compression method from stem compression to "table lookup"
  *      compression
  *
  *      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%.
  *
  */

 #define _GNU_SOURCE

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>

 #define KSYM_NAME_LEN		127


 struct sym_entry {
 	unsigned long long addr;
 	unsigned int len;
 	unsigned char *sym;
 };


 static struct sym_entry *table;
 static unsigned int table_size, table_cnt;
 static unsigned long long _text, _stext, _etext, _sinittext, _einittext, _sextratext, _eextratext;
 static int all_symbols = 0;
 static char symbol_prefix_char = '\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>] < 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("atd", str[1])
 	       && (str[2] == '\0' || str[2] == '.');
 }

 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) {
 			/* skip line */
 			fgets(str, 500, in);
 		}
 		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 (strcmp(sym, "_stext") == 0)
 		_stext = s->addr;
 	else if (strcmp(sym, "_etext") == 0)
 		_etext = s->addr;
 	else if (strcmp(sym, "_sinittext") == 0)
 		_sinittext = s->addr;
 	else if (strcmp(sym, "_einittext") == 0)
 		_einittext = s->addr;
 	else if (strcmp(sym, "_sextratext") == 0)
 		_sextratext = s->addr;
 	else if (strcmp(sym, "_eextratext") == 0)
 		_eextratext = s->addr;
 	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;

 	/* 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;

 	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_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 };
 	int i;
 	int offset = 1;

 	/* skip prefix char */
 	if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char)
 		offset++;

 	/* if --all-symbols is not specified, then symbols outside the text
 	 * and inittext sections are discarded */
 	if (!all_symbols) {
 		if ((s->addr < _stext || s->addr > _etext)
 		    && (s->addr < _sinittext || s->addr > _einittext)
 		    && (s->addr < _sextratext || s->addr > _eextratext))
 			return 0;
 		/* Corner case.  Discard any symbols with the same value as
 		 * _etext _einittext or _eextratext; 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 == _etext && strcmp((char*)s->sym + offset, "_etext")) ||
 		    (s->addr == _einittext && strcmp((char*)s->sym + offset, "_einittext")) ||
 		    (s->addr == _eextratext && strcmp((char*)s->sym + offset, "_eextratext")))
 			return 0;
 	}

 	/* Exclude symbols which vary between passes. */
 	if (strstr((char *)s->sym + offset, "_compiled."))
 		return 0;

 	for (i = 0; special_symbols[i]; i++)
 		if( strcmp((char *)s->sym + offset, special_symbols[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_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 void write_src(void)
 {
 	unsigned int i, k, off;
 	unsigned int best_idx[256];
 	unsigned int *markers;
 	char buf[KSYM_NAME_LEN+1];

 	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(".data\n");

 	/* Provide proper symbols relocatability by their '_text'
 	 * relativeness.  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.
 	 */
 	output_label("kallsyms_addresses");
 	for (i = 0; i < table_cnt; i++) {
 		if (toupper(table[i].sym[0]) != 'A') {
 			printf("\tPTR\t_text + %#llx\n",
 				table[i].addr - _text);
 		} else {
 			printf("\tPTR\t%#llx\n", table[i].addr);
 		}
 	}
 	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;

 	pos = 0;
 	for (i = 0; i < table_cnt; i++) {
 		if ( symbol_valid(&table[i]) ) {
 			if (pos != i)
 				table[pos] = table[i];
 			learn_symbol(table[pos].sym, table[pos].len);
 			pos++;
 		}
 	}
 	table_cnt = pos;
 }

 /* replace a given token in all the valid symbols. Use the sampled symbols
  * to update the counts */
 static void compress_symbols(unsigned char *str, int idx)
 {
 	unsigned int i, len, size;
 	unsigned char *p1, *p2;

 	for (i = 0; i < table_cnt; i++) {

 		len = table[i].len;
 		p1 = table[i].sym;

 		/* find the token on the symbol */
 		p2 = memmem(p1, len, str, 2);
 		if (!p2) continue;

 		/* decrease the counts for this symbol's tokens */
 		forget_symbol(table[i].sym, len);

 		size = len;

 		do {
 			*p2 = idx;
 			p2++;
 			size -= (p2 - p1);
 			memmove(p2, p2 + 1, size);
 			p1 = p2;
 			len--;

 			if (size < 2) break;

 			/* find the token on the symbol */
 			p2 = memmem(p1, size, str, 2);

 		} while (p2);

 		table[i].len = len;

 		/* increase the counts for this symbol's new tokens */
 		learn_symbol(table[i].sym, len);
 	}
 }

 /* search the token with the maximum profit */
 static int find_best_token(void)
 {
 	int i, best, bestprofit;

 	bestprofit=-10000;
 	best = 0;

 	for (i = 0; i < 0x10000; i++) {
 		if (token_profit[i] > bestprofit) {
 			best = i;
 			bestprofit = token_profit[i];
 		}
 	}
 	return best;
 }

 /* this is the core of the algorithm: calculate the "best" table */
 static void optimize_result(void)
 {
 	int i, best;

 	/* using the '\0' symbol last allows compress_symbols to use standard
 	 * fast string functions */
 	for (i = 255; i >= 0; i--) {

 		/* if this table slot is empty (it is not used by an actual
 		 * original char code */
 		if (!best_table_len[i]) {

 			/* find the token with the breates profit value */
 			best = find_best_token();

 			/* place it in the "best" table */
 			best_table_len[i] = 2;
 			best_table[i][0] = best & 0xFF;
 			best_table[i][1] = (best >> 8) & 0xFF;

 			/* replace this token in all the valid symbols */
 			compress_symbols(best_table[i], i);
 		}
 	}
 }

 /* start by placing the symbols that are actually used on the table */
 static void insert_real_symbols_in_table(void)
 {
 	unsigned int i, j, c;

 	memset(best_table, 0, sizeof(best_table));
 	memset(best_table_len, 0, sizeof(best_table_len));

 	for (i = 0; i < table_cnt; i++) {
 		for (j = 0; j < table[i].len; j++) {
 			c = table[i].sym[j];
 			best_table[c][0]=c;
 			best_table_len[c]=1;
 		}
 	}
 }

 static void optimize_token_table(void)
 {
 	build_initial_tok_table();

 	insert_real_symbols_in_table();

 	/* When valid symbol is not registered, exit to error */
 	if (!table_cnt) {
 		fprintf(stderr, "No valid symbol.\n");
 		exit(1);
 	}

 	optimize_result();
 }


 int main(int argc, char **argv)
 {
 	if (argc >= 2) {
 		int i;
 		for (i = 1; i < argc; i++) {
 			if(strcmp(argv[i], "--all-symbols") == 0)
 				all_symbols = 1;
 			else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) {
 				char *p = &argv[i][16];
 				/* skip quote */
 				if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
 					p++;
 				symbol_prefix_char = *p;
 			} else
 				usage();
 		}
 	} else if (argc != 1)
 		usage();

 	read_map(stdin);
 	optimize_token_table();
 	write_src();

 	return 0;
 }
	/* 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
	*
	* ChangeLog:
	*
	* (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
	* Changed the compression method from stem compression to "table lookup"
	* compression
	*
	* 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%.
	*
	*/

	#define _GNU_SOURCE

	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <ctype.h>

	#define KSYM_NAME_LEN 127


	struct sym_entry {
	unsigned long long addr;
	unsigned int len;
	unsigned char *sym;
	};


	static struct sym_entry *table;
	static unsigned int table_size, table_cnt;
	static unsigned long long _text, _stext, _etext, _sinittext, _einittext, _sextratext, _eextratext;
	static int all_symbols = 0;
	static char symbol_prefix_char = '\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>] < 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("atd", str[1])
	&& (str[2] == '\0' \|\| str[2] == '.');
	}

	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) {
	/* skip line */
	fgets(str, 500, in);
	}
	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 (strcmp(sym, "_stext") == 0)
	_stext = s->addr;
	else if (strcmp(sym, "_etext") == 0)
	_etext = s->addr;
	else if (strcmp(sym, "_sinittext") == 0)
	_sinittext = s->addr;
	else if (strcmp(sym, "_einittext") == 0)
	_einittext = s->addr;
	else if (strcmp(sym, "_sextratext") == 0)
	_sextratext = s->addr;
	else if (strcmp(sym, "_eextratext") == 0)
	_eextratext = s->addr;
	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;

	/* 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;

	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_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 };
	int i;
	int offset = 1;

	/* skip prefix char */
	if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char)
	offset++;

	/* if --all-symbols is not specified, then symbols outside the text
	* and inittext sections are discarded */
	if (!all_symbols) {
	if ((s->addr < _stext \|\| s->addr > _etext)
	&& (s->addr < _sinittext \|\| s->addr > _einittext)
	&& (s->addr < _sextratext \|\| s->addr > _eextratext))
	return 0;
	/* Corner case. Discard any symbols with the same value as
	* _etext _einittext or _eextratext; 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 == _etext && strcmp((char*)s->sym + offset, "_etext")) \|\|
	(s->addr == _einittext && strcmp((char*)s->sym + offset, "_einittext")) \|\|
	(s->addr == _eextratext && strcmp((char*)s->sym + offset, "_eextratext")))
	return 0;
	}

	/* Exclude symbols which vary between passes. */
	if (strstr((char *)s->sym + offset, "_compiled."))
	return 0;

	for (i = 0; special_symbols[i]; i++)
	if( strcmp((char *)s->sym + offset, special_symbols[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_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 void write_src(void)
	{
	unsigned int i, k, off;
	unsigned int best_idx[256];
	unsigned int *markers;
	char buf[KSYM_NAME_LEN+1];

	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(".data\n");

	/* Provide proper symbols relocatability by their '_text'
	* relativeness. 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.
	*/
	output_label("kallsyms_addresses");
	for (i = 0; i < table_cnt; i++) {
	if (toupper(table[i].sym[0]) != 'A') {
	printf("\tPTR\t_text + %#llx\n",
	table[i].addr - _text);
	} else {
	printf("\tPTR\t%#llx\n", table[i].addr);
	}
	}
	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;

	pos = 0;
	for (i = 0; i < table_cnt; i++) {
	if ( symbol_valid(&table[i]) ) {
	if (pos != i)
	table[pos] = table[i];
	learn_symbol(table[pos].sym, table[pos].len);
	pos++;
	}
	}
	table_cnt = pos;
	}

	/* replace a given token in all the valid symbols. Use the sampled symbols
	* to update the counts */
	static void compress_symbols(unsigned char *str, int idx)
	{
	unsigned int i, len, size;
	unsigned char p1, p2;

	for (i = 0; i < table_cnt; i++) {

	len = table[i].len;
	p1 = table[i].sym;

	/* find the token on the symbol */
	p2 = memmem(p1, len, str, 2);
	if (!p2) continue;

	/* decrease the counts for this symbol's tokens */
	forget_symbol(table[i].sym, len);

	size = len;

	do {
	*p2 = idx;
	p2++;
	size -= (p2 - p1);
	memmove(p2, p2 + 1, size);
	p1 = p2;
	len--;

	if (size < 2) break;

	/* find the token on the symbol */
	p2 = memmem(p1, size, str, 2);

	} while (p2);

	table[i].len = len;

	/* increase the counts for this symbol's new tokens */
	learn_symbol(table[i].sym, len);
	}
	}

	/* search the token with the maximum profit */
	static int find_best_token(void)
	{
	int i, best, bestprofit;

	bestprofit=-10000;
	best = 0;

	for (i = 0; i < 0x10000; i++) {
	if (token_profit[i] > bestprofit) {
	best = i;
	bestprofit = token_profit[i];
	}
	}
	return best;
	}

	/* this is the core of the algorithm: calculate the "best" table */
	static void optimize_result(void)
	{
	int i, best;

	/* using the '\0' symbol last allows compress_symbols to use standard
	* fast string functions */
	for (i = 255; i >= 0; i--) {

	/* if this table slot is empty (it is not used by an actual
	* original char code */
	if (!best_table_len[i]) {

	/* find the token with the breates profit value */
	best = find_best_token();

	/* place it in the "best" table */
	best_table_len[i] = 2;
	best_table[i][0] = best & 0xFF;
	best_table[i][1] = (best >> 8) & 0xFF;

	/* replace this token in all the valid symbols */
	compress_symbols(best_table[i], i);
	}
	}
	}

	/* start by placing the symbols that are actually used on the table */
	static void insert_real_symbols_in_table(void)
	{
	unsigned int i, j, c;

	memset(best_table, 0, sizeof(best_table));
	memset(best_table_len, 0, sizeof(best_table_len));

	for (i = 0; i < table_cnt; i++) {
	for (j = 0; j < table[i].len; j++) {
	c = table[i].sym[j];
	best_table[c][0]=c;
	best_table_len[c]=1;
	}
	}
	}

	static void optimize_token_table(void)
	{
	build_initial_tok_table();

	insert_real_symbols_in_table();

	/* When valid symbol is not registered, exit to error */
	if (!table_cnt) {
	fprintf(stderr, "No valid symbol.\n");
	exit(1);
	}

	optimize_result();
	}


	int main(int argc, char **argv)
	{
	if (argc >= 2) {
	int i;
	for (i = 1; i < argc; i++) {
	if(strcmp(argv[i], "--all-symbols") == 0)
	all_symbols = 1;
	else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) {
	char *p = &argv[i][16];
	/* skip quote */
	if ((p == '"' && (p+2) == '"') \|\| (p == '\'' && (p+2) == '\''))
	p++;
	symbol_prefix_char = *p;
	} else
	usage();
	}
	} else if (argc != 1)
	usage();

	read_map(stdin);
	optimize_token_table();
	write_src();

	return 0;
	}