1 /* 2 * MIPS Relocation Data Generator 3 * 4 * Copyright (c) 2017 Imagination Technologies Ltd. 5 * 6 * SPDX-License-Identifier: GPL-2.0+ 7 */ 8 9 #include <elf.h> 10 #include <errno.h> 11 #include <fcntl.h> 12 #include <limits.h> 13 #include <stdio.h> 14 #include <stdlib.h> 15 #include <sys/mman.h> 16 #include <sys/stat.h> 17 #include <unistd.h> 18 19 #include <asm/relocs.h> 20 21 #define hdr_field(pfx, idx, field) ({ \ 22 uint64_t _val; \ 23 unsigned int _size; \ 24 \ 25 if (is_64) { \ 26 _val = pfx##hdr64[idx].field; \ 27 _size = sizeof(pfx##hdr64[0].field); \ 28 } else { \ 29 _val = pfx##hdr32[idx].field; \ 30 _size = sizeof(pfx##hdr32[0].field); \ 31 } \ 32 \ 33 switch (_size) { \ 34 case 1: \ 35 break; \ 36 case 2: \ 37 _val = is_be ? be16toh(_val) : le16toh(_val); \ 38 break; \ 39 case 4: \ 40 _val = is_be ? be32toh(_val) : le32toh(_val); \ 41 break; \ 42 case 8: \ 43 _val = is_be ? be64toh(_val) : le64toh(_val); \ 44 break; \ 45 } \ 46 \ 47 _val; \ 48 }) 49 50 #define set_hdr_field(pfx, idx, field, val) ({ \ 51 uint64_t _val; \ 52 unsigned int _size; \ 53 \ 54 if (is_64) \ 55 _size = sizeof(pfx##hdr64[0].field); \ 56 else \ 57 _size = sizeof(pfx##hdr32[0].field); \ 58 \ 59 switch (_size) { \ 60 case 1: \ 61 _val = val; \ 62 break; \ 63 case 2: \ 64 _val = is_be ? htobe16(val) : htole16(val); \ 65 break; \ 66 case 4: \ 67 _val = is_be ? htobe32(val) : htole32(val); \ 68 break; \ 69 case 8: \ 70 _val = is_be ? htobe64(val) : htole64(val); \ 71 break; \ 72 } \ 73 \ 74 if (is_64) \ 75 pfx##hdr64[idx].field = _val; \ 76 else \ 77 pfx##hdr32[idx].field = _val; \ 78 }) 79 80 #define ehdr_field(field) \ 81 hdr_field(e, 0, field) 82 #define phdr_field(idx, field) \ 83 hdr_field(p, idx, field) 84 #define shdr_field(idx, field) \ 85 hdr_field(s, idx, field) 86 87 #define set_phdr_field(idx, field, val) \ 88 set_hdr_field(p, idx, field, val) 89 #define set_shdr_field(idx, field, val) \ 90 set_hdr_field(s, idx, field, val) 91 92 #define shstr(idx) (&shstrtab[idx]) 93 94 bool is_64, is_be; 95 uint64_t text_base; 96 97 struct mips_reloc { 98 uint8_t type; 99 uint64_t offset; 100 } *relocs; 101 size_t relocs_sz, relocs_idx; 102 103 static int add_reloc(unsigned int type, uint64_t off) 104 { 105 struct mips_reloc *new; 106 size_t new_sz; 107 108 switch (type) { 109 case R_MIPS_NONE: 110 case R_MIPS_LO16: 111 case R_MIPS_PC16: 112 case R_MIPS_HIGHER: 113 case R_MIPS_HIGHEST: 114 case R_MIPS_PC21_S2: 115 case R_MIPS_PC26_S2: 116 /* Skip these relocs */ 117 return 0; 118 119 default: 120 break; 121 } 122 123 if (relocs_idx == relocs_sz) { 124 new_sz = relocs_sz ? relocs_sz * 2 : 128; 125 new = realloc(relocs, new_sz * sizeof(*relocs)); 126 if (!new) { 127 fprintf(stderr, "Out of memory\n"); 128 return -ENOMEM; 129 } 130 131 relocs = new; 132 relocs_sz = new_sz; 133 } 134 135 relocs[relocs_idx++] = (struct mips_reloc){ 136 .type = type, 137 .offset = off, 138 }; 139 140 return 0; 141 } 142 143 static int parse_mips32_rel(const void *_rel) 144 { 145 const Elf32_Rel *rel = _rel; 146 uint32_t off, type; 147 148 off = is_be ? be32toh(rel->r_offset) : le32toh(rel->r_offset); 149 off -= text_base; 150 151 type = is_be ? be32toh(rel->r_info) : le32toh(rel->r_info); 152 type = ELF32_R_TYPE(type); 153 154 return add_reloc(type, off); 155 } 156 157 static int parse_mips64_rela(const void *_rel) 158 { 159 const Elf64_Rela *rel = _rel; 160 uint64_t off, type; 161 162 off = is_be ? be64toh(rel->r_offset) : le64toh(rel->r_offset); 163 off -= text_base; 164 165 type = rel->r_info >> (64 - 8); 166 167 return add_reloc(type, off); 168 } 169 170 static void output_uint(uint8_t **buf, uint64_t val) 171 { 172 uint64_t tmp; 173 174 do { 175 tmp = val & 0x7f; 176 val >>= 7; 177 tmp |= !!val << 7; 178 *(*buf)++ = tmp; 179 } while (val); 180 } 181 182 static int compare_relocs(const void *a, const void *b) 183 { 184 const struct mips_reloc *ra = a, *rb = b; 185 186 return ra->offset - rb->offset; 187 } 188 189 int main(int argc, char *argv[]) 190 { 191 unsigned int i, j, i_rel_shdr, sh_type, sh_entsize, sh_entries; 192 size_t rel_size, rel_actual_size, load_sz; 193 const char *shstrtab, *sh_name, *rel_pfx; 194 int (*parse_fn)(const void *rel); 195 uint8_t *buf_start, *buf; 196 const Elf32_Ehdr *ehdr32; 197 const Elf64_Ehdr *ehdr64; 198 uintptr_t sh_offset; 199 Elf32_Phdr *phdr32; 200 Elf64_Phdr *phdr64; 201 Elf32_Shdr *shdr32; 202 Elf64_Shdr *shdr64; 203 struct stat st; 204 int err, fd; 205 void *elf; 206 bool skip; 207 208 fd = open(argv[1], O_RDWR); 209 if (fd == -1) { 210 fprintf(stderr, "Unable to open input file %s\n", argv[1]); 211 err = errno; 212 goto out_ret; 213 } 214 215 err = fstat(fd, &st); 216 if (err) { 217 fprintf(stderr, "Unable to fstat() input file\n"); 218 goto out_close_fd; 219 } 220 221 elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); 222 if (elf == MAP_FAILED) { 223 fprintf(stderr, "Unable to mmap() input file\n"); 224 err = errno; 225 goto out_close_fd; 226 } 227 228 ehdr32 = elf; 229 ehdr64 = elf; 230 231 if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) { 232 fprintf(stderr, "Input file is not an ELF\n"); 233 err = -EINVAL; 234 goto out_free_relocs; 235 } 236 237 if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) { 238 fprintf(stderr, "Unrecognised ELF version\n"); 239 err = -EINVAL; 240 goto out_free_relocs; 241 } 242 243 switch (ehdr32->e_ident[EI_CLASS]) { 244 case ELFCLASS32: 245 is_64 = false; 246 break; 247 case ELFCLASS64: 248 is_64 = true; 249 break; 250 default: 251 fprintf(stderr, "Unrecognised ELF class\n"); 252 err = -EINVAL; 253 goto out_free_relocs; 254 } 255 256 switch (ehdr32->e_ident[EI_DATA]) { 257 case ELFDATA2LSB: 258 is_be = false; 259 break; 260 case ELFDATA2MSB: 261 is_be = true; 262 break; 263 default: 264 fprintf(stderr, "Unrecognised ELF data encoding\n"); 265 err = -EINVAL; 266 goto out_free_relocs; 267 } 268 269 if (ehdr_field(e_type) != ET_EXEC) { 270 fprintf(stderr, "Input ELF is not an executable\n"); 271 printf("type 0x%lx\n", ehdr_field(e_type)); 272 err = -EINVAL; 273 goto out_free_relocs; 274 } 275 276 if (ehdr_field(e_machine) != EM_MIPS) { 277 fprintf(stderr, "Input ELF does not target MIPS\n"); 278 err = -EINVAL; 279 goto out_free_relocs; 280 } 281 282 phdr32 = elf + ehdr_field(e_phoff); 283 phdr64 = elf + ehdr_field(e_phoff); 284 shdr32 = elf + ehdr_field(e_shoff); 285 shdr64 = elf + ehdr_field(e_shoff); 286 shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset); 287 288 i_rel_shdr = UINT_MAX; 289 for (i = 0; i < ehdr_field(e_shnum); i++) { 290 sh_name = shstr(shdr_field(i, sh_name)); 291 292 if (!strcmp(sh_name, ".rel")) { 293 i_rel_shdr = i; 294 continue; 295 } 296 297 if (!strcmp(sh_name, ".text")) { 298 text_base = shdr_field(i, sh_addr); 299 continue; 300 } 301 } 302 if (i_rel_shdr == UINT_MAX) { 303 fprintf(stderr, "Unable to find .rel section\n"); 304 err = -EINVAL; 305 goto out_free_relocs; 306 } 307 if (!text_base) { 308 fprintf(stderr, "Unable to find .text base address\n"); 309 err = -EINVAL; 310 goto out_free_relocs; 311 } 312 313 rel_pfx = is_64 ? ".rela." : ".rel."; 314 315 for (i = 0; i < ehdr_field(e_shnum); i++) { 316 sh_type = shdr_field(i, sh_type); 317 if ((sh_type != SHT_REL) && (sh_type != SHT_RELA)) 318 continue; 319 320 sh_name = shstr(shdr_field(i, sh_name)); 321 if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) { 322 if (strcmp(sh_name, ".rel") && strcmp(sh_name, ".rel.dyn")) 323 fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name); 324 continue; 325 } 326 327 /* 328 * Skip reloc sections which either don't correspond to another 329 * section in the ELF, or whose corresponding section isn't 330 * loaded as part of the U-Boot binary (ie. doesn't have the 331 * alloc flags set). 332 */ 333 skip = true; 334 for (j = 0; j < ehdr_field(e_shnum); j++) { 335 if (strcmp(&sh_name[strlen(rel_pfx) - 1], shstr(shdr_field(j, sh_name)))) 336 continue; 337 338 skip = !(shdr_field(j, sh_flags) & SHF_ALLOC); 339 break; 340 } 341 if (skip) 342 continue; 343 344 sh_offset = shdr_field(i, sh_offset); 345 sh_entsize = shdr_field(i, sh_entsize); 346 sh_entries = shdr_field(i, sh_size) / sh_entsize; 347 348 if (sh_type == SHT_REL) { 349 if (is_64) { 350 fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n"); 351 err = -EINVAL; 352 goto out_free_relocs; 353 } else { 354 parse_fn = parse_mips32_rel; 355 } 356 } else { 357 if (is_64) { 358 parse_fn = parse_mips64_rela; 359 } else { 360 fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n"); 361 err = -EINVAL; 362 goto out_free_relocs; 363 } 364 } 365 366 for (j = 0; j < sh_entries; j++) { 367 err = parse_fn(elf + sh_offset + (j * sh_entsize)); 368 if (err) 369 goto out_free_relocs; 370 } 371 } 372 373 /* Sort relocs in ascending order of offset */ 374 qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs); 375 376 /* Make reloc offsets relative to their predecessor */ 377 for (i = relocs_idx - 1; i > 0; i--) 378 relocs[i].offset -= relocs[i - 1].offset; 379 380 /* Write the relocations to the .rel section */ 381 buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset); 382 for (i = 0; i < relocs_idx; i++) { 383 output_uint(&buf, relocs[i].type); 384 output_uint(&buf, relocs[i].offset >> 2); 385 } 386 387 /* Write a terminating R_MIPS_NONE (0) */ 388 output_uint(&buf, R_MIPS_NONE); 389 390 /* Ensure the relocs didn't overflow the .rel section */ 391 rel_size = shdr_field(i_rel_shdr, sh_size); 392 rel_actual_size = buf - buf_start; 393 if (rel_actual_size > rel_size) { 394 fprintf(stderr, "Relocs overflowed .rel section\n"); 395 return -ENOMEM; 396 } 397 398 /* Update the .rel section's size */ 399 set_shdr_field(i_rel_shdr, sh_size, rel_actual_size); 400 401 /* Shrink the PT_LOAD program header filesz (ie. shrink u-boot.bin) */ 402 for (i = 0; i < ehdr_field(e_phnum); i++) { 403 if (phdr_field(i, p_type) != PT_LOAD) 404 continue; 405 406 load_sz = phdr_field(i, p_filesz); 407 load_sz -= rel_size - rel_actual_size; 408 set_phdr_field(i, p_filesz, load_sz); 409 break; 410 } 411 412 /* Make sure data is written back to the file */ 413 err = msync(elf, st.st_size, MS_SYNC); 414 if (err) { 415 fprintf(stderr, "Failed to msync: %d\n", errno); 416 goto out_free_relocs; 417 } 418 419 out_free_relocs: 420 free(relocs); 421 munmap(elf, st.st_size); 422 out_close_fd: 423 close(fd); 424 out_ret: 425 return err; 426 } 427