| #include <stdlib.h> |
| #include <stdio.h> |
| #include <stdarg.h> |
| #include <inttypes.h> |
| #include <elf.h> |
| #include <unistd.h> |
| #include <fcntl.h> |
| |
| #include "thunk.h" |
| |
| /* all dynamically generated functions begin with this code */ |
| #define OP_PREFIX "op" |
| |
| int elf_must_swap(Elf32_Ehdr *h) |
| { |
| union { |
| uint32_t i; |
| uint8_t b[4]; |
| } swaptest; |
| |
| swaptest.i = 1; |
| return (h->e_ident[EI_DATA] == ELFDATA2MSB) != |
| (swaptest.b[0] == 0); |
| } |
| |
| void swab16s(uint16_t *p) |
| { |
| *p = bswap16(*p); |
| } |
| |
| void swab32s(uint32_t *p) |
| { |
| *p = bswap32(*p); |
| } |
| |
| void swab64s(uint32_t *p) |
| { |
| *p = bswap64(*p); |
| } |
| |
| void elf_swap_ehdr(Elf32_Ehdr *h) |
| { |
| swab16s(&h->e_type); /* Object file type */ |
| swab16s(&h-> e_machine); /* Architecture */ |
| swab32s(&h-> e_version); /* Object file version */ |
| swab32s(&h-> e_entry); /* Entry point virtual address */ |
| swab32s(&h-> e_phoff); /* Program header table file offset */ |
| swab32s(&h-> e_shoff); /* Section header table file offset */ |
| swab32s(&h-> e_flags); /* Processor-specific flags */ |
| swab16s(&h-> e_ehsize); /* ELF header size in bytes */ |
| swab16s(&h-> e_phentsize); /* Program header table entry size */ |
| swab16s(&h-> e_phnum); /* Program header table entry count */ |
| swab16s(&h-> e_shentsize); /* Section header table entry size */ |
| swab16s(&h-> e_shnum); /* Section header table entry count */ |
| swab16s(&h-> e_shstrndx); /* Section header string table index */ |
| } |
| |
| void elf_swap_shdr(Elf32_Shdr *h) |
| { |
| swab32s(&h-> sh_name); /* Section name (string tbl index) */ |
| swab32s(&h-> sh_type); /* Section type */ |
| swab32s(&h-> sh_flags); /* Section flags */ |
| swab32s(&h-> sh_addr); /* Section virtual addr at execution */ |
| swab32s(&h-> sh_offset); /* Section file offset */ |
| swab32s(&h-> sh_size); /* Section size in bytes */ |
| swab32s(&h-> sh_link); /* Link to another section */ |
| swab32s(&h-> sh_info); /* Additional section information */ |
| swab32s(&h-> sh_addralign); /* Section alignment */ |
| swab32s(&h-> sh_entsize); /* Entry size if section holds table */ |
| } |
| |
| void elf_swap_phdr(Elf32_Phdr *h) |
| { |
| swab32s(&h->p_type); /* Segment type */ |
| swab32s(&h->p_offset); /* Segment file offset */ |
| swab32s(&h->p_vaddr); /* Segment virtual address */ |
| swab32s(&h->p_paddr); /* Segment physical address */ |
| swab32s(&h->p_filesz); /* Segment size in file */ |
| swab32s(&h->p_memsz); /* Segment size in memory */ |
| swab32s(&h->p_flags); /* Segment flags */ |
| swab32s(&h->p_align); /* Segment alignment */ |
| } |
| |
| int do_swap; |
| int e_machine; |
| |
| uint16_t get16(uint16_t *p) |
| { |
| uint16_t val; |
| val = *p; |
| if (do_swap) |
| val = bswap16(val); |
| return val; |
| } |
| |
| uint32_t get32(uint32_t *p) |
| { |
| uint32_t val; |
| val = *p; |
| if (do_swap) |
| val = bswap32(val); |
| return val; |
| } |
| |
| void put16(uint16_t *p, uint16_t val) |
| { |
| if (do_swap) |
| val = bswap16(val); |
| *p = val; |
| } |
| |
| void put32(uint32_t *p, uint32_t val) |
| { |
| if (do_swap) |
| val = bswap32(val); |
| *p = val; |
| } |
| |
| void __attribute__((noreturn)) error(const char *fmt, ...) |
| { |
| va_list ap; |
| va_start(ap, fmt); |
| fprintf(stderr, "dyngen: "); |
| vfprintf(stderr, fmt, ap); |
| fprintf(stderr, "\n"); |
| va_end(ap); |
| exit(1); |
| } |
| |
| |
| Elf32_Shdr *find_elf_section(Elf32_Shdr *shdr, int shnum, const char *shstr, |
| const char *name) |
| { |
| int i; |
| const char *shname; |
| Elf32_Shdr *sec; |
| |
| for(i = 0; i < shnum; i++) { |
| sec = &shdr[i]; |
| if (!sec->sh_name) |
| continue; |
| shname = shstr + sec->sh_name; |
| if (!strcmp(shname, name)) |
| return sec; |
| } |
| return NULL; |
| } |
| |
| void *load_data(int fd, long offset, unsigned int size) |
| { |
| char *data; |
| |
| data = malloc(size); |
| if (!data) |
| return NULL; |
| lseek(fd, offset, SEEK_SET); |
| if (read(fd, data, size) != size) { |
| free(data); |
| return NULL; |
| } |
| return data; |
| } |
| |
| int strstart(const char *str, const char *val, const char **ptr) |
| { |
| const char *p, *q; |
| p = str; |
| q = val; |
| while (*q != '\0') { |
| if (*p != *q) |
| return 0; |
| p++; |
| q++; |
| } |
| if (ptr) |
| *ptr = p; |
| return 1; |
| } |
| |
| #define MAX_ARGS 3 |
| |
| /* generate op code */ |
| void gen_code(const char *name, unsigned long offset, unsigned long size, |
| FILE *outfile, uint8_t *text, void *relocs, int nb_relocs, int reloc_sh_type, |
| Elf32_Sym *symtab, char *strtab) |
| { |
| int copy_size = 0; |
| uint8_t *p_start, *p_end; |
| int nb_args, i; |
| uint8_t args_present[MAX_ARGS]; |
| const char *sym_name, *p; |
| |
| /* compute exact size excluding return instruction */ |
| p_start = text + offset; |
| p_end = p_start + size; |
| switch(e_machine) { |
| case EM_386: |
| { |
| uint8_t *p; |
| p = p_end - 1; |
| /* find ret */ |
| while (p > p_start && *p != 0xc3) |
| p--; |
| /* skip double ret */ |
| if (p > p_start && p[-1] == 0xc3) |
| p--; |
| if (p == p_start) |
| error("empty code for %s", name); |
| copy_size = p - p_start; |
| } |
| break; |
| case EM_PPC: |
| { |
| uint8_t *p; |
| p = (void *)(p_end - 4); |
| /* find ret */ |
| while (p > p_start && get32((uint32_t *)p) != 0x4e800020) |
| p -= 4; |
| /* skip double ret */ |
| if (p > p_start && get32((uint32_t *)(p - 4)) == 0x4e800020) |
| p -= 4; |
| if (p == p_start) |
| error("empty code for %s", name); |
| copy_size = p - p_start; |
| } |
| break; |
| default: |
| error("unsupported CPU (%d)", e_machine); |
| } |
| |
| /* compute the number of arguments by looking at the relocations */ |
| for(i = 0;i < MAX_ARGS; i++) |
| args_present[i] = 0; |
| |
| if (reloc_sh_type == SHT_REL) { |
| Elf32_Rel *rel; |
| int n; |
| for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) { |
| if (rel->r_offset >= offset && rel->r_offset < offset + copy_size) { |
| sym_name = strtab + symtab[ELF32_R_SYM(rel->r_info)].st_name; |
| if (strstart(sym_name, "__op_param", &p)) { |
| n = strtoul(p, NULL, 10); |
| if (n >= MAX_ARGS) |
| error("too many arguments in %s", name); |
| args_present[n - 1] = 1; |
| } |
| } |
| } |
| } else { |
| Elf32_Rela *rel; |
| int n; |
| for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) { |
| if (rel->r_offset >= offset && rel->r_offset < offset + copy_size) { |
| sym_name = strtab + symtab[ELF32_R_SYM(rel->r_info)].st_name; |
| if (strstart(sym_name, "__op_param", &p)) { |
| n = strtoul(p, NULL, 10); |
| if (n >= MAX_ARGS) |
| error("too many arguments in %s", name); |
| args_present[n - 1] = 1; |
| } |
| } |
| } |
| } |
| |
| nb_args = 0; |
| while (nb_args < MAX_ARGS && args_present[nb_args]) |
| nb_args++; |
| for(i = nb_args; i < MAX_ARGS; i++) { |
| if (args_present[i]) |
| error("inconsistent argument numbering in %s", name); |
| } |
| |
| /* output C code */ |
| fprintf(outfile, "extern void %s();\n", name); |
| fprintf(outfile, "static inline void gen_%s(", name); |
| if (nb_args == 0) { |
| fprintf(outfile, "void"); |
| } else { |
| for(i = 0; i < nb_args; i++) { |
| if (i != 0) |
| fprintf(outfile, ", "); |
| fprintf(outfile, "long param%d", i + 1); |
| } |
| } |
| fprintf(outfile, ")\n"); |
| fprintf(outfile, "{\n"); |
| fprintf(outfile, " memcpy(gen_code_ptr, &%s, %d);\n", name, copy_size); |
| |
| /* patch relocations */ |
| switch(e_machine) { |
| case EM_386: |
| { |
| Elf32_Rel *rel; |
| char name[256]; |
| int type; |
| long addend; |
| for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) { |
| if (rel->r_offset >= offset && rel->r_offset < offset + copy_size) { |
| sym_name = strtab + symtab[ELF32_R_SYM(rel->r_info)].st_name; |
| if (strstart(sym_name, "__op_param", &p)) { |
| snprintf(name, sizeof(name), "param%s", p); |
| } else { |
| snprintf(name, sizeof(name), "(long)(&%s)", sym_name); |
| } |
| type = ELF32_R_TYPE(rel->r_info); |
| addend = get32((uint32_t *)(text + rel->r_offset)); |
| switch(type) { |
| case R_386_32: |
| fprintf(outfile, " *(uint32_t *)(gen_code_ptr + %ld) = %s + %ld;\n", |
| rel->r_offset - offset, name, addend); |
| break; |
| case R_386_PC32: |
| fprintf(outfile, " *(uint32_t *)(gen_code_ptr + %ld) = %s - (long)(gen_code_ptr + %ld) + %ld;\n", |
| rel->r_offset - offset, name, rel->r_offset - offset, addend); |
| break; |
| default: |
| error("unsupported i386 relocation (%d)", type); |
| } |
| } |
| } |
| } |
| break; |
| default: |
| error("unsupported CPU for relocations (%d)", e_machine); |
| } |
| |
| |
| fprintf(outfile, " gen_code_ptr += %d;\n", copy_size); |
| fprintf(outfile, "}\n\n"); |
| } |
| |
| /* load an elf object file */ |
| int load_elf(const char *filename, FILE *outfile) |
| { |
| int fd; |
| Elf32_Ehdr ehdr; |
| Elf32_Shdr *sec, *shdr, *symtab_sec, *strtab_sec, *text_sec; |
| int i, j, nb_syms; |
| Elf32_Sym *symtab, *sym; |
| const char *cpu_name; |
| char *shstr, *strtab; |
| uint8_t *text; |
| void *relocs; |
| int nb_relocs, reloc_sh_type; |
| |
| fd = open(filename, O_RDONLY); |
| if (fd < 0) |
| error("can't open file '%s'", filename); |
| |
| /* Read ELF header. */ |
| if (read(fd, &ehdr, sizeof (ehdr)) != sizeof (ehdr)) |
| error("unable to read file header"); |
| |
| /* Check ELF identification. */ |
| if (ehdr.e_ident[EI_MAG0] != ELFMAG0 |
| || ehdr.e_ident[EI_MAG1] != ELFMAG1 |
| || ehdr.e_ident[EI_MAG2] != ELFMAG2 |
| || ehdr.e_ident[EI_MAG3] != ELFMAG3 |
| || ehdr.e_ident[EI_CLASS] != ELFCLASS32 |
| || ehdr.e_ident[EI_VERSION] != EV_CURRENT) { |
| error("bad ELF header"); |
| } |
| |
| do_swap = elf_must_swap(&ehdr); |
| if (do_swap) |
| elf_swap_ehdr(&ehdr); |
| if (ehdr.e_type != ET_REL) |
| error("ELF object file expected"); |
| if (ehdr.e_version != EV_CURRENT) |
| error("Invalid ELF version"); |
| e_machine = ehdr.e_machine; |
| |
| /* read section headers */ |
| shdr = load_data(fd, ehdr.e_shoff, ehdr.e_shnum * sizeof(Elf32_Shdr)); |
| if (do_swap) { |
| for(i = 0; i < ehdr.e_shnum; i++) { |
| elf_swap_shdr(&shdr[i]); |
| } |
| } |
| |
| sec = &shdr[ehdr.e_shstrndx]; |
| shstr = load_data(fd, sec->sh_offset, sec->sh_size); |
| |
| /* text section */ |
| |
| text_sec = find_elf_section(shdr, ehdr.e_shnum, shstr, ".text"); |
| if (!text_sec) |
| error("could not find .text section"); |
| text = load_data(fd, text_sec->sh_offset, text_sec->sh_size); |
| |
| /* find text relocations, if any */ |
| nb_relocs = 0; |
| relocs = NULL; |
| reloc_sh_type = 0; |
| for(i = 0; i < ehdr.e_shnum; i++) { |
| sec = &shdr[i]; |
| if ((sec->sh_type == SHT_REL || sec->sh_type == SHT_RELA) && |
| sec->sh_info == (text_sec - shdr)) { |
| reloc_sh_type = sec->sh_type; |
| relocs = load_data(fd, sec->sh_offset, sec->sh_size); |
| nb_relocs = sec->sh_size / sec->sh_entsize; |
| if (do_swap) { |
| if (sec->sh_type == SHT_REL) { |
| Elf32_Rel *rel = relocs; |
| for(j = 0, rel = relocs; j < nb_relocs; j++, rel++) { |
| swab32s(&rel->r_offset); |
| swab32s(&rel->r_info); |
| } |
| } else { |
| Elf32_Rela *rel = relocs; |
| for(j = 0, rel = relocs; j < nb_relocs; j++, rel++) { |
| swab32s(&rel->r_offset); |
| swab32s(&rel->r_info); |
| swab32s(&rel->r_addend); |
| } |
| } |
| } |
| break; |
| } |
| } |
| |
| symtab_sec = find_elf_section(shdr, ehdr.e_shnum, shstr, ".symtab"); |
| if (!symtab_sec) |
| error("could not find .symtab section"); |
| strtab_sec = &shdr[symtab_sec->sh_link]; |
| |
| symtab = load_data(fd, symtab_sec->sh_offset, symtab_sec->sh_size); |
| strtab = load_data(fd, strtab_sec->sh_offset, strtab_sec->sh_size); |
| |
| nb_syms = symtab_sec->sh_size / sizeof(Elf32_Sym); |
| if (do_swap) { |
| for(i = 0, sym = symtab; i < nb_syms; i++, sym++) { |
| swab32s(&sym->st_name); |
| swab32s(&sym->st_value); |
| swab32s(&sym->st_size); |
| swab16s(&sym->st_shndx); |
| } |
| } |
| |
| switch(e_machine) { |
| case EM_386: |
| cpu_name = "i386"; |
| break; |
| case EM_PPC: |
| cpu_name = "ppc"; |
| break; |
| case EM_MIPS: |
| cpu_name = "mips"; |
| break; |
| case EM_ARM: |
| cpu_name = "arm"; |
| break; |
| case EM_SPARC: |
| cpu_name = "sparc"; |
| break; |
| default: |
| error("unsupported CPU (e_machine=%d)", e_machine); |
| } |
| |
| fprintf(outfile, "#include \"gen-%s.h\"\n\n", cpu_name); |
| |
| for(i = 0, sym = symtab; i < nb_syms; i++, sym++) { |
| const char *name; |
| name = strtab + sym->st_name; |
| if (strstart(name, "op_", NULL) || |
| strstart(name, "op1_", NULL) || |
| strstart(name, "op2_", NULL) || |
| strstart(name, "op3_", NULL)) { |
| #if 0 |
| printf("%4d: %s pos=0x%08x len=%d\n", |
| i, name, sym->st_value, sym->st_size); |
| #endif |
| if (sym->st_shndx != (text_sec - shdr)) |
| error("invalid section for opcode (0x%x)", sym->st_shndx); |
| gen_code(name, sym->st_value, sym->st_size, outfile, |
| text, relocs, nb_relocs, reloc_sh_type, symtab, strtab); |
| } |
| } |
| |
| close(fd); |
| return 0; |
| } |
| |
| void usage(void) |
| { |
| printf("dyngen (c) 2003 Fabrice Bellard\n" |
| "usage: dyngen [-o outfile] objfile\n" |
| "Generate a dynamic code generator from an object file\n"); |
| exit(1); |
| } |
| |
| int main(int argc, char **argv) |
| { |
| int c; |
| const char *filename, *outfilename; |
| FILE *outfile; |
| |
| outfilename = "out.c"; |
| for(;;) { |
| c = getopt(argc, argv, "ho:"); |
| if (c == -1) |
| break; |
| switch(c) { |
| case 'h': |
| usage(); |
| break; |
| case 'o': |
| outfilename = optarg; |
| break; |
| } |
| } |
| if (optind >= argc) |
| usage(); |
| filename = argv[optind]; |
| outfile = fopen(outfilename, "w"); |
| if (!outfile) |
| error("could not open '%s'", outfilename); |
| load_elf(filename, outfile); |
| fclose(outfile); |
| return 0; |
| } |
