* 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 <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;
+ char *sym;
};
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)
{
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)
{
_sinittext = s->addr;
else if (strcmp(str, "_einittext") == 0)
_einittext = s->addr;
- else if (toupper(s->type) == 'A')
- {
- /* Keep these useful absolute symbols */
- if (strcmp(str, "__kernel_syscall_via_break") &&
- strcmp(str, "__kernel_syscall_via_epc") &&
- strcmp(str, "__kernel_sigtramp") &&
- strcmp(str, "__gp"))
- return -1;
-
- }
- else if (toupper(s->type) == 'U' ||
- is_arm_mapping_symbol(str))
+ 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;
-
+ s->sym = strdup(str);
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."))
+ /* Exclude 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.
+ */
+ if (strstr(s->sym, "_compiled.") ||
+ strcmp(s->sym, "kallsyms_addresses") == 0 ||
+ strcmp(s->sym, "kallsyms_num_syms") == 0 ||
+ strcmp(s->sym, "kallsyms_names") == 0)
return 0;
- for (i = 0; special_symbols[i]; i++)
- if( strcmp(s->sym + 1, special_symbols[i]) == 0 )
- return 0;
+ /* Exclude linker generated symbols which vary between passes */
+ if (strcmp(s->sym, "_SDA_BASE_") == 0 || /* ppc */
+ strcmp(s->sym, "_SDA2_BASE_") == 0) /* ppc */
+ return 0;
return 1;
}
}
}
-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];
+ int i, valid = 0;
+ char *prev;
printf("#include <asm/types.h>\n");
printf("#if BITS_PER_LONG == 64\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;
+ printf(".globl kallsyms_addresses\n");
+ printf("\tALGN\n");
+ printf("kallsyms_addresses:\n");
for (i = 0; i < cnt; i++) {
-
- if (!table[i].flags & SYM_FLAG_VALID)
+ if (!symbol_valid(&table[i]))
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;
+ printf("\tPTR\t%#llx\n", table[i].addr);
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(".globl kallsyms_num_syms\n");
+ printf("\tALGN\n");
+ printf("kallsyms_num_syms:\n");
+ printf("\tPTR\t%d\n", valid);
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;
+ printf(".globl kallsyms_names\n");
+ printf("\tALGN\n");
+ printf("kallsyms_names:\n");
+ prev = "";
for (i = 0; i < cnt; i++) {
+ int k;
- 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;
+ if (!symbol_valid(&table[i]))
+ continue;
- memset(best_table, 0, sizeof(best_table));
- memset(best_table_len, 0, sizeof(best_table_len));
+ for (k = 0; table[i].sym[k] && table[i].sym[k] == prev[k]; ++k)
+ ;
- 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;
- }
- }
+ printf("\t.byte 0x%02x\n\t.asciz\t\"%s\"\n", k, table[i].sym + k);
+ prev = table[i].sym;
}
+ printf("\n");
}
-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)
{
usage();
read_map(stdin);
- optimize_token_table();
write_src();
return 0;
git://git.onelab.eu / linux-2.6.git / blobdiff