2.6.32-458

#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, _***tratext, _eextratext;
 static int all_symbols = 0;
 static char symbol_prefix_char = ”;

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] == ” || 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, “_***tratext”) == 0)
 _***tratext = 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 < _***tratext || 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 < 0×10000; 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 ” 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;
 }