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Diffstat (limited to 'scripts/kallsyms.c')
| -rw-r--r-- | scripts/kallsyms.c | 920 |
1 files changed, 920 insertions, 0 deletions
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c new file mode 100644 index 000000000..ff8cce175 --- /dev/null +++ b/scripts/kallsyms.c @@ -0,0 +1,920 @@ +/* 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: kallsyms [--all-symbols] [--absolute-percpu] + * [--base-relative] [--lto-clang] in.map > out.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 <getopt.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <ctype.h> +#include <limits.h> + +#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0])) + +#define _stringify_1(x) #x +#define _stringify(x) _stringify_1(x) + +#define KSYM_NAME_LEN 512 + +/* + * A substantially bigger size than the current maximum. + * + * It cannot be defined as an expression because it gets stringified + * for the fscanf() format string. Therefore, a _Static_assert() is + * used instead to maintain the relationship with KSYM_NAME_LEN. + */ +#define KSYM_NAME_LEN_BUFFER 2048 +_Static_assert( + KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4, + "Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN" +); + +struct sym_entry { + unsigned long long addr; + unsigned int len; + unsigned int seq; + unsigned int start_pos; + unsigned int percpu_absolute; + unsigned char sym[]; +}; + +struct addr_range { + const char *start_sym, *end_sym; + unsigned long long start, end; +}; + +static unsigned long long _text; +static unsigned long long relative_base; +static struct addr_range text_ranges[] = { + { "_stext", "_etext" }, + { "_sinittext", "_einittext" }, +}; +#define text_range_text (&text_ranges[0]) +#define text_range_inittext (&text_ranges[1]) + +static struct addr_range percpu_range = { + "__per_cpu_start", "__per_cpu_end", -1ULL, 0 +}; + +static struct sym_entry **table; +static unsigned int table_size, table_cnt; +static int all_symbols; +static int absolute_percpu; +static int base_relative; +static int lto_clang; + +static int token_profit[0x10000]; + +/* the table that holds the result of the compression */ +static unsigned char best_table[256][2]; +static unsigned char best_table_len[256]; + + +static void usage(void) +{ + fprintf(stderr, "Usage: kallsyms [--all-symbols] [--absolute-percpu] " + "[--base-relative] [--lto-clang] in.map > out.S\n"); + exit(1); +} + +static char *sym_name(const struct sym_entry *s) +{ + return (char *)s->sym + 1; +} + +static bool is_ignored_symbol(const char *name, char type) +{ + /* Symbol names that exactly match to the following are ignored.*/ + static const char * const ignored_symbols[] = { + /* + * 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. + */ + "kallsyms_addresses", + "kallsyms_offsets", + "kallsyms_relative_base", + "kallsyms_num_syms", + "kallsyms_names", + "kallsyms_markers", + "kallsyms_token_table", + "kallsyms_token_index", + "kallsyms_seqs_of_names", + /* Exclude linker generated symbols which vary between passes */ + "_SDA_BASE_", /* ppc */ + "_SDA2_BASE_", /* ppc */ + NULL + }; + + /* Symbol names that begin with the following are ignored.*/ + static const char * const ignored_prefixes[] = { + "__efistub_", /* arm64 EFI stub namespace */ + "__kvm_nvhe_$", /* arm64 local symbols in non-VHE KVM namespace */ + "__kvm_nvhe_.L", /* arm64 local symbols in non-VHE KVM namespace */ + "__AArch64ADRPThunk_", /* arm64 lld */ + "__ARMV5PILongThunk_", /* arm lld */ + "__ARMV7PILongThunk_", + "__ThumbV7PILongThunk_", + "__LA25Thunk_", /* mips lld */ + "__microLA25Thunk_", + "__kcfi_typeid_", /* CFI type identifiers */ + NULL + }; + + /* Symbol names that end with the following are ignored.*/ + static const char * const ignored_suffixes[] = { + "_from_arm", /* arm */ + "_from_thumb", /* arm */ + "_veneer", /* arm */ + NULL + }; + + /* Symbol names that contain the following are ignored.*/ + static const char * const ignored_matches[] = { + ".long_branch.", /* ppc stub */ + ".plt_branch.", /* ppc stub */ + NULL + }; + + const char * const *p; + + for (p = ignored_symbols; *p; p++) + if (!strcmp(name, *p)) + return true; + + for (p = ignored_prefixes; *p; p++) + if (!strncmp(name, *p, strlen(*p))) + return true; + + for (p = ignored_suffixes; *p; p++) { + int l = strlen(name) - strlen(*p); + + if (l >= 0 && !strcmp(name + l, *p)) + return true; + } + + for (p = ignored_matches; *p; p++) { + if (strstr(name, *p)) + return true; + } + + if (type == 'U' || type == 'u') + return true; + /* exclude debugging symbols */ + if (type == 'N' || type == 'n') + return true; + + if (toupper(type) == 'A') { + /* Keep these useful absolute symbols */ + if (strcmp(name, "__kernel_syscall_via_break") && + strcmp(name, "__kernel_syscall_via_epc") && + strcmp(name, "__kernel_sigtramp") && + strcmp(name, "__gp")) + return true; + } + + return false; +} + +static void check_symbol_range(const char *sym, unsigned long long addr, + struct addr_range *ranges, int entries) +{ + size_t i; + struct addr_range *ar; + + for (i = 0; i < entries; ++i) { + ar = &ranges[i]; + + if (strcmp(sym, ar->start_sym) == 0) { + ar->start = addr; + return; + } else if (strcmp(sym, ar->end_sym) == 0) { + ar->end = addr; + return; + } + } +} + +static struct sym_entry *read_symbol(FILE *in) +{ + char name[KSYM_NAME_LEN_BUFFER+1], type; + unsigned long long addr; + unsigned int len; + struct sym_entry *sym; + int rc; + + rc = fscanf(in, "%llx %c %" _stringify(KSYM_NAME_LEN_BUFFER) "s\n", &addr, &type, name); + if (rc != 3) { + if (rc != EOF && fgets(name, ARRAY_SIZE(name), in) == NULL) + fprintf(stderr, "Read error or end of file.\n"); + return NULL; + } + if (strlen(name) >= KSYM_NAME_LEN) { + fprintf(stderr, "Symbol %s too long for kallsyms (%zu >= %d).\n" + "Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n", + name, strlen(name), KSYM_NAME_LEN); + return NULL; + } + + if (strcmp(name, "_text") == 0) + _text = addr; + + /* Ignore most absolute/undefined (?) symbols. */ + if (is_ignored_symbol(name, type)) + return NULL; + + check_symbol_range(name, addr, text_ranges, ARRAY_SIZE(text_ranges)); + check_symbol_range(name, addr, &percpu_range, 1); + + /* include the type field in the symbol name, so that it gets + * compressed together */ + + len = strlen(name) + 1; + + sym = malloc(sizeof(*sym) + len + 1); + if (!sym) { + fprintf(stderr, "kallsyms failure: " + "unable to allocate required amount of memory\n"); + exit(EXIT_FAILURE); + } + sym->addr = addr; + sym->len = len; + sym->sym[0] = type; + strcpy(sym_name(sym), name); + sym->percpu_absolute = 0; + + return sym; +} + +static int symbol_in_range(const struct sym_entry *s, + const struct addr_range *ranges, int entries) +{ + size_t i; + const struct addr_range *ar; + + for (i = 0; i < entries; ++i) { + ar = &ranges[i]; + + if (s->addr >= ar->start && s->addr <= ar->end) + return 1; + } + + return 0; +} + +static int symbol_valid(const struct sym_entry *s) +{ + const char *name = sym_name(s); + + /* if --all-symbols is not specified, then symbols outside the text + * and inittext sections are discarded */ + if (!all_symbols) { + if (symbol_in_range(s, text_ranges, + ARRAY_SIZE(text_ranges)) == 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(name, text_range_text->end_sym)) || + (s->addr == text_range_inittext->end && + strcmp(name, text_range_inittext->end_sym))) + return 0; + } + + return 1; +} + +/* remove all the invalid symbols from the table */ +static void shrink_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]; + pos++; + } else { + free(table[i]); + } + } + table_cnt = pos; + + /* When valid symbol is not registered, exit to error */ + if (!table_cnt) { + fprintf(stderr, "No valid symbol.\n"); + exit(1); + } +} + +static void read_map(const char *in) +{ + FILE *fp; + struct sym_entry *sym; + + fp = fopen(in, "r"); + if (!fp) { + perror(in); + exit(1); + } + + while (!feof(fp)) { + sym = read_symbol(fp); + if (!sym) + continue; + + sym->start_pos = table_cnt; + + if (table_cnt >= table_size) { + table_size += 10000; + table = realloc(table, sizeof(*table) * table_size); + if (!table) { + fprintf(stderr, "out of memory\n"); + fclose(fp); + exit (1); + } + } + + table[table_cnt++] = sym; + } + + fclose(fp); +} + +static void output_label(const char *label) +{ + printf(".globl %s\n", label); + printf("\tALGN\n"); + printf("%s:\n", label); +} + +/* Provide proper symbols relocatability by their '_text' relativeness. */ +static void output_address(unsigned long long addr) +{ + if (_text <= addr) + printf("\tPTR\t_text + %#llx\n", addr - _text); + else + printf("\tPTR\t_text - %#llx\n", _text - addr); +} + +/* 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(const 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 int symbol_absolute(const struct sym_entry *s) +{ + return s->percpu_absolute; +} + +static char * s_name(char *buf) +{ + /* Skip the symbol type */ + return buf + 1; +} + +static void cleanup_symbol_name(char *s) +{ + char *p; + + if (!lto_clang) + return; + + /* + * ASCII[.] = 2e + * ASCII[0-9] = 30,39 + * ASCII[A-Z] = 41,5a + * ASCII[_] = 5f + * ASCII[a-z] = 61,7a + * + * As above, replacing the first '.' in ".llvm." with '\0' does not + * affect the main sorting, but it helps us with subsorting. + */ + p = strstr(s, ".llvm."); + if (p) + *p = '\0'; +} + +static int compare_names(const void *a, const void *b) +{ + int ret; + char sa_namebuf[KSYM_NAME_LEN]; + char sb_namebuf[KSYM_NAME_LEN]; + const struct sym_entry *sa = *(const struct sym_entry **)a; + const struct sym_entry *sb = *(const struct sym_entry **)b; + + expand_symbol(sa->sym, sa->len, sa_namebuf); + expand_symbol(sb->sym, sb->len, sb_namebuf); + cleanup_symbol_name(s_name(sa_namebuf)); + cleanup_symbol_name(s_name(sb_namebuf)); + ret = strcmp(s_name(sa_namebuf), s_name(sb_namebuf)); + if (!ret) { + if (sa->addr > sb->addr) + return 1; + else if (sa->addr < sb->addr) + return -1; + + /* keep old order */ + return (int)(sa->seq - sb->seq); + } + + return ret; +} + +static void sort_symbols_by_name(void) +{ + qsort(table, table_cnt, sizeof(table[0]), compare_names); +} + +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/bitsperlong.h>\n"); + printf("#if BITS_PER_LONG == 64\n"); + printf("#define PTR .quad\n"); + printf("#define ALGN .balign 8\n"); + printf("#else\n"); + printf("#define PTR .long\n"); + printf("#define ALGN .balign 4\n"); + printf("#endif\n"); + + printf("\t.section .rodata, \"a\"\n"); + + if (!base_relative) + output_label("kallsyms_addresses"); + else + output_label("kallsyms_offsets"); + + for (i = 0; i < table_cnt; i++) { + if (base_relative) { + /* + * Use the offset relative to the lowest value + * encountered of all relative symbols, and emit + * non-relocatable fixed offsets that will be fixed + * up at runtime. + */ + + long long offset; + int overflow; + + if (!absolute_percpu) { + offset = table[i]->addr - relative_base; + overflow = (offset < 0 || offset > UINT_MAX); + } else if (symbol_absolute(table[i])) { + offset = table[i]->addr; + overflow = (offset < 0 || offset > INT_MAX); + } else { + offset = relative_base - table[i]->addr - 1; + overflow = (offset < INT_MIN || offset >= 0); + } + if (overflow) { + fprintf(stderr, "kallsyms failure: " + "%s symbol value %#llx out of range in relative mode\n", + symbol_absolute(table[i]) ? "absolute" : "relative", + table[i]->addr); + exit(EXIT_FAILURE); + } + printf("\t.long\t%#x\n", (int)offset); + } else if (!symbol_absolute(table[i])) { + output_address(table[i]->addr); + } else { + printf("\tPTR\t%#llx\n", table[i]->addr); + } + } + printf("\n"); + + if (base_relative) { + output_label("kallsyms_relative_base"); + output_address(relative_base); + printf("\n"); + } + + output_label("kallsyms_num_syms"); + printf("\t.long\t%u\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; + table[i]->seq = i; + + /* There cannot be any symbol of length zero. */ + if (table[i]->len == 0) { + fprintf(stderr, "kallsyms failure: " + "unexpected zero symbol length\n"); + exit(EXIT_FAILURE); + } + + /* Only lengths that fit in up-to-two-byte ULEB128 are supported. */ + if (table[i]->len > 0x3FFF) { + fprintf(stderr, "kallsyms failure: " + "unexpected huge symbol length\n"); + exit(EXIT_FAILURE); + } + + /* Encode length with ULEB128. */ + if (table[i]->len <= 0x7F) { + /* Most symbols use a single byte for the length. */ + printf("\t.byte 0x%02x", table[i]->len); + off += table[i]->len + 1; + } else { + /* "Big" symbols use two bytes. */ + printf("\t.byte 0x%02x, 0x%02x", + (table[i]->len & 0x7F) | 0x80, + (table[i]->len >> 7) & 0x7F); + off += table[i]->len + 2; + } + for (k = 0; k < table[i]->len; k++) + printf(", 0x%02x", table[i]->sym[k]); + printf("\n"); + } + printf("\n"); + + output_label("kallsyms_markers"); + for (i = 0; i < ((table_cnt + 255) >> 8); i++) + printf("\t.long\t%u\n", markers[i]); + printf("\n"); + + free(markers); + + sort_symbols_by_name(); + output_label("kallsyms_seqs_of_names"); + for (i = 0; i < table_cnt; i++) + printf("\t.byte 0x%02x, 0x%02x, 0x%02x\n", + (unsigned char)(table[i]->seq >> 16), + (unsigned char)(table[i]->seq >> 8), + (unsigned char)(table[i]->seq >> 0)); + printf("\n"); + + 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(const 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(const unsigned char *symbol, int len) +{ + int i; + + for (i = 0; i < len - 1; i++) + token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--; +} + +/* do the initial token count */ +static void build_initial_tok_table(void) +{ + unsigned int i; + + for (i = 0; i < table_cnt; i++) + learn_symbol(table[i]->sym, table[i]->len); +} + +static unsigned char *find_token(unsigned char *str, int len, + const 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(const 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 best 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; + + 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(); + + optimize_result(); +} + +/* guess for "linker script provide" symbol */ +static int may_be_linker_script_provide_symbol(const struct sym_entry *se) +{ + const char *symbol = sym_name(se); + 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 compare_symbols(const void *a, const void *b) +{ + const struct sym_entry *sa = *(const struct sym_entry **)a; + const struct sym_entry *sb = *(const struct sym_entry **)b; + int wa, wb; + + /* 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 = strspn(sym_name(sa), "_"); + wb = strspn(sym_name(sb), "_"); + 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(table[0]), compare_symbols); +} + +static void make_percpus_absolute(void) +{ + unsigned int i; + + for (i = 0; i < table_cnt; i++) + if (symbol_in_range(table[i], &percpu_range, 1)) { + /* + * Keep the 'A' override for percpu symbols to + * ensure consistent behavior compared to older + * versions of this tool. + */ + table[i]->sym[0] = 'A'; + table[i]->percpu_absolute = 1; + } +} + +/* find the minimum non-absolute symbol address */ +static void record_relative_base(void) +{ + unsigned int i; + + for (i = 0; i < table_cnt; i++) + if (!symbol_absolute(table[i])) { + /* + * The table is sorted by address. + * Take the first non-absolute symbol value. + */ + relative_base = table[i]->addr; + return; + } +} + +int main(int argc, char **argv) +{ + while (1) { + static struct option long_options[] = { + {"all-symbols", no_argument, &all_symbols, 1}, + {"absolute-percpu", no_argument, &absolute_percpu, 1}, + {"base-relative", no_argument, &base_relative, 1}, + {"lto-clang", no_argument, <o_clang, 1}, + {}, + }; + + int c = getopt_long(argc, argv, "", long_options, NULL); + + if (c == -1) + break; + if (c != 0) + usage(); + } + + if (optind >= argc) + usage(); + + read_map(argv[optind]); + shrink_table(); + if (absolute_percpu) + make_percpus_absolute(); + sort_symbols(); + if (base_relative) + record_relative_base(); + optimize_token_table(); + write_src(); + + return 0; +} |