* 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;
- char type;
- char *sym;
+ unsigned int len;
+ unsigned char *sym;
};
static struct sym_entry *table;
-static int size, cnt;
-static unsigned long long _stext, _etext, _sinittext, _einittext;
+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];
-static void
-usage(void)
+/* 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] < in.map > out.S\n");
+ fprintf(stderr, "Usage: kallsyms [--all-symbols] [--symbol-prefix=<prefix char>] < in.map > out.S\n");
exit(1);
}
-static int
-read_symbol(FILE *in, struct sym_entry *s)
+/*
+ * 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, &s->type, str);
+ rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str);
if (rc != 3) {
if (rc != EOF) {
/* skip line */
return -1;
}
+ sym = str;
+ /* skip prefix char */
+ if (symbol_prefix_char && str[0] == symbol_prefix_char)
+ sym++;
+
/* Ignore most absolute/undefined (?) symbols. */
- if (strcmp(str, "_stext") == 0)
+ if (strcmp(sym, "_text") == 0)
+ _text = s->addr;
+ else if (strcmp(sym, "_stext") == 0)
_stext = s->addr;
- else if (strcmp(str, "_etext") == 0)
+ else if (strcmp(sym, "_etext") == 0)
_etext = s->addr;
- else if (strcmp(str, "_sinittext") == 0)
+ else if (strcmp(sym, "_sinittext") == 0)
_sinittext = s->addr;
- else if (strcmp(str, "_einittext") == 0)
+ else if (strcmp(sym, "_einittext") == 0)
_einittext = s->addr;
- else if (toupper(s->type) == 'A' || toupper(s->type) == 'U')
+ 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;
- s->sym = strdup(str);
+ /* 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)
+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 < _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;
}
- if (strstr(s->sym, "_compiled."))
+ /* 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)
+static void read_map(FILE *in)
{
while (!feof(in)) {
- if (cnt >= size) {
- size += 10000;
- table = realloc(table, sizeof(*table) * size);
+ 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[cnt]) == 0)
- cnt++;
+ 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)
+static void write_src(void)
{
- int i, valid = 0;
- char *prev;
+ 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 ALGN .align 4\n");
printf("#endif\n");
- printf(".data\n");
+ printf("\t.section .rodata, \"a\"\n");
- printf(".globl kallsyms_addresses\n");
- printf("\tALGN\n");
- printf("kallsyms_addresses:\n");
- for (i = 0; i < cnt; i++) {
- if (!symbol_valid(&table[i]))
- continue;
-
- printf("\tPTR\t%#llx\n", table[i].addr);
- valid++;
+ /* 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') {
+ 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");
- printf(".globl kallsyms_num_syms\n");
- printf("\tALGN\n");
- printf("kallsyms_num_syms:\n");
- printf("\tPTR\t%d\n", valid);
+ output_label("kallsyms_num_syms");
+ printf("\tPTR\t%d\n", table_cnt);
printf("\n");
- printf(".globl kallsyms_names\n");
- printf("\tALGN\n");
- printf("kallsyms_names:\n");
- prev = "";
- for (i = 0; i < cnt; i++) {
- int k;
+ /* 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);
+ }
- if (!symbol_valid(&table[i]))
- continue;
+ output_label("kallsyms_names");
+ off = 0;
+ for (i = 0; i < table_cnt; i++) {
+ if ((i & 0xFF) == 0)
+ markers[i >> 8] = off;
- for (k = 0; table[i].sym[k] && table[i].sym[k] == prev[k]; ++k)
- ;
+ 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");
- printf("\t.byte 0x%02x\n\t.asciz\t\"%s\"\n", k, table[i].sym + k);
- prev = table[i].sym;
+ 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;
}
-int
-main(int argc, char **argv)
+/* this is the core of the algorithm: calculate the "best" table */
+static void optimize_result(void)
{
- if (argc == 2 && strcmp(argv[1], "--all-symbols") == 0)
- all_symbols = 1;
- else if (argc != 1)
+ 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;
}
-
git://git.onelab.eu / linux-2.6.git / blobdiff