Attachment #67560 for bug #104393

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 *
 */

#define _GNU_SOURCE

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

/* maximum token length used. It doesn't pay to increase it a lot, because
 * very long substrings probably don't repeat themselves too often. */
#define MAX_TOK_SIZE		11
#define KSYM_NAME_LEN		127

/* we use only a subset of the complete symbol table to gather the token count,
 * to speed up compression, at the expense of a little compression ratio */
#define WORKING_SET		1024

/* first find the best token only on the list of tokens that would profit more
 * than GOOD_BAD_THRESHOLD. Only if this list is empty go to the "bad" list.
 * Increasing this value will put less tokens on the "good" list, so the search
 * is faster. However, if the good list runs out of tokens, we must painfully
 * search the bad list. */
#define GOOD_BAD_THRESHOLD	10

/* token hash parameters */
#define HASH_BITS		18
#define HASH_TABLE_SIZE		(1 << HASH_BITS)
#define HASH_MASK		(HASH_TABLE_SIZE - 1)
#define HASH_BASE_OFFSET	2166136261U
#define HASH_FOLD(a)		((a)&(HASH_MASK))

/* flags to mark symbols */
#define SYM_FLAG_VALID		1
#define SYM_FLAG_SAMPLED	2

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


static struct sym_entry *table;
static unsigned int table_size, table_cnt;
static unsigned long long _stext, _etext, _sinittext, _einittext, _sextratext, _eextratext;
static int all_symbols = 0;
static char symbol_prefix_char = '\0';

int token_profit[0x10000];
	unsigned char data[MAX_TOK_SIZE];
	unsigned char len;
	/* profit: the number of bytes that could be saved by inserting this
	 * token into the table */
	int profit;
	struct token *next;	/* next token on the hash list */
	struct token *right;	/* next token on the good/bad list */
	struct token *left;    /* previous token on the good/bad list */
	struct token *smaller; /* token that is less one letter than this one */
	};

struct token bad_head, good_head;
struct token *hash_table[HASH_TABLE_SIZE];

/* 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)
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 $d.
 */
static inline int is_arm_mapping_symbol(const char *str)
is_arm_mapping_symbol(const char *str)
{
	return str[0] == '$' && strchr("atd", str[1])
	       && (str[2] == '\0' || str[2] == '.');
}

static int read_symbol(FILE *in, struct sym_entry *s)
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 */

		_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") &&

			return -1;

	}
	else if (toupper(stype) == 'U' ||
		 is_arm_mapping_symbol(sym))
		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);
	strcpy((char *)s->sym + 1, str);
	s->sym[0] = stype;

	return 0;
}

static int symbol_valid(struct sym_entry *s)
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

	}

	/* 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)
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++;
	}
}


	return total;
}

static void write_src(void)
write_src(void)
{
	unsigned int i, k, off;
	unsigned int best_idx[256];
	unsigned int *markers;
	char buf[KSYM_NAME_LEN+1];

	printf(".data\n");

	output_label("kallsyms_addresses");
	for (i = 0; i < table_cnt; i++) {
		printf("\tPTR\t%#llx\n", table[i].addr);
		if (table[i].flags & SYM_FLAG_VALID) {
			printf("\tPTR\t%#llx\n", table[i].addr);
			valid++;
		}
	}
	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 = (unsigned int *) malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));

	output_label("kallsyms_names");
	valid = 0;
	off = 0;
	for (i = 0; i < table_cnt; i++) {
		if ((i & 0xFF) == 0)
			markers[i >> 8] = off;
			continue;

		if ((valid & 0xFF) == 0)
			markers[valid >> 8] = off;

		printf("\t.byte 0x%02x", table[i].len);
		for (k = 0; k < table[i].len; k++)

		printf("\n");

		off += table[i].len + 1;
		valid++;
	}
	printf("\n");

	output_label("kallsyms_markers");
	for (i = 0; i < ((table_cnt + 255) >> 8); i++)
		printf("\tPTR\t%d\n", markers[i]);
	printf("\n");


	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;
	}


/* table lookup compression functions */

static inline unsigned int rehash_token(unsigned int hash, unsigned char data)
{
	return ((hash * 16777619) ^ data);
}

static unsigned int hash_token(unsigned char *data, int len)
{
	unsigned int hash=HASH_BASE_OFFSET;
	int i;

	for (i = 0; i < len; i++)
		hash = rehash_token(hash, data[i]);

	return HASH_FOLD(hash);
}

/* find a token given its data and hash value */
static struct token *find_token_hash(unsigned char *data, int len, unsigned int hash)
{
	struct token *ptr;

	ptr = hash_table[hash];

	while (ptr) {
		if ((ptr->len == len) && (memcmp(ptr->data, data, len) == 0))
			return ptr;
		ptr=ptr->next;
	}

	return NULL;
}

static inline void insert_token_in_group(struct token *head, struct token *ptr)
{
	ptr->right = head->right;
	ptr->right->left = ptr;
	head->right = ptr;
	ptr->left = head;
}

static inline void remove_token_from_group(struct token *ptr)
{
	ptr->left->right = ptr->right;
	ptr->right->left = ptr->left;
}


/* build the counts for all the tokens that start with "data", and have lenghts
 * from 2 to "len" */
static void learn_token(unsigned char *data, int len)
{
	struct token *ptr,*last_ptr;
	int i, newprofit;
	unsigned int hash = HASH_BASE_OFFSET;
	unsigned int hashes[MAX_TOK_SIZE + 1];

	if (len > MAX_TOK_SIZE)
		len = MAX_TOK_SIZE;

	/* calculate and store the hash values for all the sub-tokens */
	hash = rehash_token(hash, data[0]);
	for (i = 2; i <= len; i++) {
		hash = rehash_token(hash, data[i-1]);
		hashes[i] = HASH_FOLD(hash);
	}

	last_ptr = NULL;
	ptr = NULL;

	for (i = len; i >= 2; i--) {
		hash = hashes[i];

		if (!ptr) ptr = find_token_hash(data, i, hash);

		if (!ptr) {
			/* create a new token entry */
			ptr = (struct token *) malloc(sizeof(*ptr));

			memcpy(ptr->data, data, i);
			ptr->len = i;

			/* when we create an entry, it's profit is 0 because
			 * we also take into account the size of the token on
			 * the compressed table. We then subtract GOOD_BAD_THRESHOLD
			 * so that the test to see if this token belongs to
			 * the good or bad list, is a comparison to zero */
			ptr->profit = -GOOD_BAD_THRESHOLD;

			ptr->next = hash_table[hash];
			hash_table[hash] = ptr;

			insert_token_in_group(&bad_head, ptr);

			ptr->smaller = NULL;
		} else {
			newprofit = ptr->profit + (ptr->len - 1);
			/* check to see if this token needs to be moved to a
			 * different list */
			if((ptr->profit < 0) && (newprofit >= 0)) {
				remove_token_from_group(ptr);
				insert_token_in_group(&good_head,ptr);
			}
			ptr->profit = newprofit;
		}

		if (last_ptr) last_ptr->smaller = ptr;
		last_ptr = ptr;

		ptr = ptr->smaller;
	}
}

/* decrease the counts for all the tokens that start with "data", and have lenghts
 * from 2 to "len". This function is much simpler than learn_token because we have
 * more guarantees (tho tokens exist, the ->smaller pointer is set, etc.)
 * The two separate functions exist only because of compression performance */
static void forget_token(unsigned char *data, int len)
{
	struct token *ptr;
	int i, newprofit;
	unsigned int hash=0;

	if (len > MAX_TOK_SIZE) len = MAX_TOK_SIZE;

	hash = hash_token(data, len);
	ptr = find_token_hash(data, len, hash);

	for (i = len; i >= 2; i--) {

		newprofit = ptr->profit - (ptr->len - 1);
		if ((ptr->profit >= 0) && (newprofit < 0)) {
			remove_token_from_group(ptr);
			insert_token_in_group(&bad_head, ptr);
		}
		ptr->profit=newprofit;

		ptr=ptr->smaller;
	}
}

/* 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 */

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

		/* subsample the available symbols. This method is almost like
		 * a Bresenham's algorithm to get uniformly distributed samples
		 * across the symbol table */
		if (table[i].flags & SYM_FLAG_VALID) {

			use_it += WORKING_SET;

			if (use_it >= valid) {
				table[i].flags |= SYM_FLAG_SAMPLED;
				use_it -= valid;
			}
		}
		if (table[i].flags & SYM_FLAG_SAMPLED)
			learn_symbol(table[i].sym, table[i].len);
	}
}

/* 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 < cnt; i++) {

	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);
			if (!p) break;

		} while (p2);
				/* if this symbol was used to count, decrease it */
				if (table[i].flags & SYM_FLAG_SAMPLED)
					forget_symbol(table[i].sym, len);
				learn = 1;
			}

		table[i].len = len;

		/* increase the counts for this symbol's new tokens */
		learn_symbol(table[i].sym, len);
			len -= tlen - 1;

		} while (size >= tlen);

		if(learn) {
			table[i].len = len;
			/* if this symbol was used to count, learn it again */
			if(table[i].flags & SYM_FLAG_SAMPLED)
				learn_symbol(table[i].sym, len);
		}
	}
}

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

	bestprofit=-10000;
	best = 0;

	for (i = 0; i < 0x10000; i++) {
		if (token_profit[i] > bestprofit) {
			best = i;
			bestprofit = token_profit[i];
	ptr = head->right;
	best = NULL;
	while (ptr != head) {
		if (ptr->profit > bestprofit) {
			bestprofit = ptr->profit;
			best = ptr;
		}
		ptr = ptr->right;
	}

	return best;
}

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

	/* using the '\0' symbol last allows compress_symbols to use standard
	 * fast string functions */

			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;
			   in compress_symbols */
			best_table[i][best_table_len[i]]='\0';

			/* 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;
				best_table_len[c]=1;
			}
		}
	}
}

static void optimize_token_table(void)
{
	memset(hash_table, 0, sizeof(hash_table));

	good_head.left = &good_head;
	good_head.right = &good_head;

	bad_head.left = &bad_head;
	bad_head.right = &bad_head;

	build_initial_tok_table();

	insert_real_symbols_in_table();

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

}


int main(int argc, char **argv)
main(int argc, char **argv)
{
	if (argc >= 2) {
		int i;

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