/* 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]) { Lines 1–500 of 661. 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/* 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]) {