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Diffstat (limited to 'scripts/kallsyms.c')
| -rw-r--r-- | scripts/kallsyms.c | 661 |
1 files changed, 661 insertions, 0 deletions
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c new file mode 100644 index 00000000..487ac6f3 --- /dev/null +++ b/scripts/kallsyms.c @@ -0,0 +1,661 @@ +/* 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 + * + * 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> + +#ifndef ARRAY_SIZE +#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0])) +#endif + +#define KSYM_NAME_LEN 128 + +struct sym_entry { + unsigned long long addr; + unsigned int len; + unsigned int start_pos; + unsigned char *sym; +}; + +struct text_range { + const char *stext, *etext; + unsigned long long start, end; +}; + +static unsigned long long _text; +static struct text_range text_ranges[] = { + { "_stext", "_etext" }, + { "_sinittext", "_einittext" }, + { "_stext_l1", "_etext_l1" }, /* Blackfin on-chip L1 inst SRAM */ + { "_stext_l2", "_etext_l2" }, /* Blackfin on-chip L2 SRAM */ +}; +#define text_range_text (&text_ranges[0]) +#define text_range_inittext (&text_ranges[1]) + +static struct sym_entry *table; +static unsigned int table_size, table_cnt; +static int all_symbols = 0; +static char symbol_prefix_char = '\0'; + +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] == '\0' || str[2] == '.'); +} + +static int read_symbol_tr(const char *sym, unsigned long long addr) +{ + size_t i; + struct text_range *tr; + + for (i = 0; i < ARRAY_SIZE(text_ranges); ++i) { + tr = &text_ranges[i]; + + if (strcmp(sym, tr->stext) == 0) { + tr->start = addr; + return 0; + } else if (strcmp(sym, tr->etext) == 0) { + tr->end = addr; + return 0; + } + } + + return 1; +} + +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 && fgets(str, 500, in) == NULL) + fprintf(stderr, "Read error or end of file.\n"); + 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 (read_symbol_tr(sym, s->addr) == 0) + /* nothing to do */; + 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; + /* exclude debugging symbols */ + else if (stype == 'N') + 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_tr(struct sym_entry *s) +{ + size_t i; + struct text_range *tr; + + for (i = 0; i < ARRAY_SIZE(text_ranges); ++i) { + tr = &text_ranges[i]; + + if (s->addr >= tr->start && s->addr <= tr->end) + return 1; + } + + 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 (symbol_valid_tr(s) == 0) + return 0; + /* Corner case. Discard any symbols with the same value as + * _etext _einittext; 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 == text_range_text->end && + strcmp((char *)s->sym + offset, text_range_text->etext)) || + (s->addr == text_range_inittext->end && + strcmp((char *)s->sym + offset, text_range_inittext->etext))) + 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[table_cnt].start_pos = table_cnt; + 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]; + + 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("\t.section .rodata, \"a\"\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') { + 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"); + + 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; +} + +static void *find_token(unsigned char *str, int len, unsigned char *token) +{ + int i; + + for (i = 0; i < len - 1; i++) { + if (str[i] == token[0] && str[i+1] == token[1]) + return &str[i]; + } + return NULL; +} + +/* 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 = find_token(p1, len, str); + 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 = find_token(p1, size, str); + + } 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; +} + +/* this is the core of the algorithm: calculate the "best" table */ +static void optimize_result(void) +{ + 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(); + if (token_profit[best] == 0) + break; + + /* 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(); +} + +/* guess for "linker script provide" symbol */ +static int may_be_linker_script_provide_symbol(const struct sym_entry *se) +{ + const char *symbol = (char *)se->sym + 1; + int len = se->len - 1; + + if (len < 8) + return 0; + + if (symbol[0] != '_' || symbol[1] != '_') + return 0; + + /* __start_XXXXX */ + if (!memcmp(symbol + 2, "start_", 6)) + return 1; + + /* __stop_XXXXX */ + if (!memcmp(symbol + 2, "stop_", 5)) + return 1; + + /* __end_XXXXX */ + if (!memcmp(symbol + 2, "end_", 4)) + return 1; + + /* __XXXXX_start */ + if (!memcmp(symbol + len - 6, "_start", 6)) + return 1; + + /* __XXXXX_end */ + if (!memcmp(symbol + len - 4, "_end", 4)) + return 1; + + return 0; +} + +static int prefix_underscores_count(const char *str) +{ + const char *tail = str; + + while (*tail == '_') + tail++; + + return tail - str; +} + +static int compare_symbols(const void *a, const void *b) +{ + const struct sym_entry *sa; + const struct sym_entry *sb; + int wa, wb; + + sa = a; + sb = b; + + /* sort by address first */ + if (sa->addr > sb->addr) + return 1; + if (sa->addr < sb->addr) + return -1; + + /* sort by "weakness" type */ + wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W'); + wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W'); + if (wa != wb) + return wa - wb; + + /* sort by "linker script provide" type */ + wa = may_be_linker_script_provide_symbol(sa); + wb = may_be_linker_script_provide_symbol(sb); + if (wa != wb) + return wa - wb; + + /* sort by the number of prefix underscores */ + wa = prefix_underscores_count((const char *)sa->sym + 1); + wb = prefix_underscores_count((const char *)sb->sym + 1); + if (wa != wb) + return wa - wb; + + /* sort by initial order, so that other symbols are left undisturbed */ + return sa->start_pos - sb->start_pos; +} + +static void sort_symbols(void) +{ + qsort(table, table_cnt, sizeof(struct sym_entry), compare_symbols); +} + +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); + sort_symbols(); + optimize_token_table(); + write_src(); + + return 0; +} |