[PATCH] DVB: misc driver updates

[linux-2.6/history.git] / scripts / kallsyms.c

/* 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%.
 *
 */

#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;
        char type;
        unsigned char flags;
        unsigned char len;
        unsigned char *sym;
};


static struct sym_entry *table;
static int size, cnt;
static unsigned long long _stext, _etext, _sinittext, _einittext;
static int all_symbols = 0;

struct token {
        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][MAX_TOK_SIZE+1];
unsigned char best_table_len[256];


static void
usage(void)
{
        fprintf(stderr, "Usage: kallsyms [--all-symbols] < in.map > out.S\n");
        exit(1);
}

static int
read_symbol(FILE *in, struct sym_entry *s)
{
        char str[500];
        int rc;

        rc = fscanf(in, "%llx %c %499s\n", &s->addr, &s->type, str);
        if (rc != 3) {
                if (rc != EOF) {
                        /* skip line */
                        fgets(str, 500, in);
                }
                return -1;
        }

        /* Ignore most absolute/undefined (?) symbols. */
        if (strcmp(str, "_stext") == 0)
                _stext = s->addr;
        else if (strcmp(str, "_etext") == 0)
                _etext = s->addr;
        else if (strcmp(str, "_sinittext") == 0)
                _sinittext = s->addr;
        else if (strcmp(str, "_einittext") == 0)
                _einittext = s->addr;
        else if (toupper(s->type) == 'A' || toupper(s->type) == 'U')
                return -1;

        /* include the type field in the symbol name, so that it gets
         * compressed together */
        s->len = strlen(str) + 1;
        s->sym = (char *) malloc(s->len + 1);
        strcpy(s->sym + 1, str);
        s->sym[0] = s->type;

        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;

        /* 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))
                        return 0;
        }

        /* Exclude symbols which vary between passes. */
        if (strstr(s->sym + 1, "_compiled."))
                return 0;

        for (i = 0; special_symbols[i]; i++)
                if( strcmp(s->sym + 1, special_symbols[i]) == 0 )
                        return 0;

        return 1;
}

static void
read_map(FILE *in)
{
        while (!feof(in)) {
                if (cnt >= size) {
                        size += 10000;
                        table = realloc(table, sizeof(*table) * size);
                        if (!table) {
                                fprintf(stderr, "out of memory\n");
                                exit (1);
                        }
                }
                if (read_symbol(in, &table[cnt]) == 0)
                        cnt++;
        }
}

static void output_label(char *label)
{
        printf(".globl %s\n",label);
        printf("\tALGN\n");
        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)
{
        int i, k, off, valid;
        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");

        output_label("kallsyms_addresses");
        valid = 0;
        for (i = 0; i < cnt; i++) {
                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", valid);
        printf("\n");

        /* table of offset markers, that give the offset in the compressed stream
         * every 256 symbols */
        markers = (unsigned int *) malloc(sizeof(unsigned int)*((valid + 255) / 256));

        output_label("kallsyms_names");
        valid = 0;
        off = 0;
        for (i = 0; i < cnt; i++) {

                if (!table[i].flags & SYM_FLAG_VALID)
                        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(", 0x%02x", table[i].sym[k]);
                printf("\n");

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

        output_label("kallsyms_markers");
        for (i = 0; i < ((valid + 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 */

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++)
                learn_token(symbol + i, len - i);
}

/* 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++)
                forget_token(symbol + i, len - i);
}

/* set all the symbol flags and do the initial token count */
static void build_initial_tok_table(void)
{
        int i, use_it, valid;

        valid = 0;
        for (i = 0; i < cnt; i++) {
                table[i].flags = 0;
                if ( symbol_valid(&table[i]) ) {
                        table[i].flags |= SYM_FLAG_VALID;
                        valid++;
                }
        }

        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 tlen, int idx)
{
        int i, len, learn, size;
        unsigned char *p;

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

                if (!(table[i].flags & SYM_FLAG_VALID)) continue;

                len = table[i].len;
                learn = 0;
                p = table[i].sym;

                do {
                        /* find the token on the symbol */
                        p = (unsigned char *) strstr((char *) p, (char *) str);
                        if (!p) break;

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

                        *p = idx;
                        size = (len - (p - table[i].sym)) - tlen + 1;
                        memmove(p + 1, p + tlen, size);
                        p++;
                        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 struct token *find_best_token(void)
{
        struct token *ptr,*best,*head;
        int bestprofit;

        bestprofit=-10000;

        /* failsafe: if the "good" list is empty search from the "bad" list */
        if(good_head.right == &good_head) head = &bad_head;
        else head = &good_head;

        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)
{
        struct token *best;
        int i;

        /* 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] = best->len;
                        memcpy(best_table[i], best->data, best_table_len[i]);
                        /* zero terminate the token so that we can use strstr
                           in compress_symbols */
                        best_table[i][best_table_len[i]]='\0';

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

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

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

        for (i = 0; i < cnt; i++) {
                if (table[i].flags & SYM_FLAG_VALID) {
                        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)
{
        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();

        optimize_result();
}


int
main(int argc, char **argv)
{
        if (argc == 2 && strcmp(argv[1], "--all-symbols") == 0)
                all_symbols = 1;
        else if (argc != 1)
                usage();

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

        return 0;
}