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 <assert.h> 10 #include <elf.h> 11 #include <errno.h> 12 #include <fcntl.h> 13 #include <limits.h> 14 #include <stdbool.h> 15 #include <stdio.h> 16 #include <stdlib.h> 17 #include <sys/mman.h> 18 #include <sys/stat.h> 19 #include <unistd.h> 20 21 #include <asm/relocs.h> 22 23 #define hdr_field(pfx, idx, field) ({ \ 24 uint64_t _val; \ 25 unsigned int _size; \ 26 \ 27 if (is_64) { \ 28 _val = pfx##hdr64[idx].field; \ 29 _size = sizeof(pfx##hdr64[0].field); \ 30 } else { \ 31 _val = pfx##hdr32[idx].field; \ 32 _size = sizeof(pfx##hdr32[0].field); \ 33 } \ 34 \ 35 switch (_size) { \ 36 case 1: \ 37 break; \ 38 case 2: \ 39 _val = is_be ? be16toh(_val) : le16toh(_val); \ 40 break; \ 41 case 4: \ 42 _val = is_be ? be32toh(_val) : le32toh(_val); \ 43 break; \ 44 case 8: \ 45 _val = is_be ? be64toh(_val) : le64toh(_val); \ 46 break; \ 47 } \ 48 \ 49 _val; \ 50 }) 51 52 #define set_hdr_field(pfx, idx, field, val) ({ \ 53 uint64_t _val; \ 54 unsigned int _size; \ 55 \ 56 if (is_64) \ 57 _size = sizeof(pfx##hdr64[0].field); \ 58 else \ 59 _size = sizeof(pfx##hdr32[0].field); \ 60 \ 61 switch (_size) { \ 62 case 1: \ 63 _val = val; \ 64 break; \ 65 case 2: \ 66 _val = is_be ? htobe16(val) : htole16(val); \ 67 break; \ 68 case 4: \ 69 _val = is_be ? htobe32(val) : htole32(val); \ 70 break; \ 71 case 8: \ 72 _val = is_be ? htobe64(val) : htole64(val); \ 73 break; \ 74 default: \ 75 /* We should never reach here */ \ 76 _val = 0; \ 77 assert(0); \ 78 break; \ 79 } \ 80 \ 81 if (is_64) \ 82 pfx##hdr64[idx].field = _val; \ 83 else \ 84 pfx##hdr32[idx].field = _val; \ 85 }) 86 87 #define ehdr_field(field) \ 88 hdr_field(e, 0, field) 89 #define phdr_field(idx, field) \ 90 hdr_field(p, idx, field) 91 #define shdr_field(idx, field) \ 92 hdr_field(s, idx, field) 93 94 #define set_phdr_field(idx, field, val) \ 95 set_hdr_field(p, idx, field, val) 96 #define set_shdr_field(idx, field, val) \ 97 set_hdr_field(s, idx, field, val) 98 99 #define shstr(idx) (&shstrtab[idx]) 100 101 bool is_64, is_be; 102 uint64_t text_base; 103 104 struct mips_reloc { 105 uint8_t type; 106 uint64_t offset; 107 } *relocs; 108 size_t relocs_sz, relocs_idx; 109 110 static int add_reloc(unsigned int type, uint64_t off) 111 { 112 struct mips_reloc *new; 113 size_t new_sz; 114 115 switch (type) { 116 case R_MIPS_NONE: 117 case R_MIPS_LO16: 118 case R_MIPS_PC16: 119 case R_MIPS_HIGHER: 120 case R_MIPS_HIGHEST: 121 case R_MIPS_PC21_S2: 122 case R_MIPS_PC26_S2: 123 /* Skip these relocs */ 124 return 0; 125 126 default: 127 break; 128 } 129 130 if (relocs_idx == relocs_sz) { 131 new_sz = relocs_sz ? relocs_sz * 2 : 128; 132 new = realloc(relocs, new_sz * sizeof(*relocs)); 133 if (!new) { 134 fprintf(stderr, "Out of memory\n"); 135 return -ENOMEM; 136 } 137 138 relocs = new; 139 relocs_sz = new_sz; 140 } 141 142 relocs[relocs_idx++] = (struct mips_reloc){ 143 .type = type, 144 .offset = off, 145 }; 146 147 return 0; 148 } 149 150 static int parse_mips32_rel(const void *_rel) 151 { 152 const Elf32_Rel *rel = _rel; 153 uint32_t off, type; 154 155 off = is_be ? be32toh(rel->r_offset) : le32toh(rel->r_offset); 156 off -= text_base; 157 158 type = is_be ? be32toh(rel->r_info) : le32toh(rel->r_info); 159 type = ELF32_R_TYPE(type); 160 161 return add_reloc(type, off); 162 } 163 164 static int parse_mips64_rela(const void *_rel) 165 { 166 const Elf64_Rela *rel = _rel; 167 uint64_t off, type; 168 169 off = is_be ? be64toh(rel->r_offset) : le64toh(rel->r_offset); 170 off -= text_base; 171 172 type = rel->r_info >> (64 - 8); 173 174 return add_reloc(type, off); 175 } 176 177 static void output_uint(uint8_t **buf, uint64_t val) 178 { 179 uint64_t tmp; 180 181 do { 182 tmp = val & 0x7f; 183 val >>= 7; 184 tmp |= !!val << 7; 185 *(*buf)++ = tmp; 186 } while (val); 187 } 188 189 static int compare_relocs(const void *a, const void *b) 190 { 191 const struct mips_reloc *ra = a, *rb = b; 192 193 return ra->offset - rb->offset; 194 } 195 196 int main(int argc, char *argv[]) 197 { 198 unsigned int i, j, i_rel_shdr, sh_type, sh_entsize, sh_entries; 199 size_t rel_size, rel_actual_size, load_sz; 200 const char *shstrtab, *sh_name, *rel_pfx; 201 int (*parse_fn)(const void *rel); 202 uint8_t *buf_start, *buf; 203 const Elf32_Ehdr *ehdr32; 204 const Elf64_Ehdr *ehdr64; 205 uintptr_t sh_offset; 206 Elf32_Phdr *phdr32; 207 Elf64_Phdr *phdr64; 208 Elf32_Shdr *shdr32; 209 Elf64_Shdr *shdr64; 210 struct stat st; 211 int err, fd; 212 void *elf; 213 bool skip; 214 215 fd = open(argv[1], O_RDWR); 216 if (fd == -1) { 217 fprintf(stderr, "Unable to open input file %s\n", argv[1]); 218 err = errno; 219 goto out_ret; 220 } 221 222 err = fstat(fd, &st); 223 if (err) { 224 fprintf(stderr, "Unable to fstat() input file\n"); 225 goto out_close_fd; 226 } 227 228 elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); 229 if (elf == MAP_FAILED) { 230 fprintf(stderr, "Unable to mmap() input file\n"); 231 err = errno; 232 goto out_close_fd; 233 } 234 235 ehdr32 = elf; 236 ehdr64 = elf; 237 238 if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) { 239 fprintf(stderr, "Input file is not an ELF\n"); 240 err = -EINVAL; 241 goto out_free_relocs; 242 } 243 244 if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) { 245 fprintf(stderr, "Unrecognised ELF version\n"); 246 err = -EINVAL; 247 goto out_free_relocs; 248 } 249 250 switch (ehdr32->e_ident[EI_CLASS]) { 251 case ELFCLASS32: 252 is_64 = false; 253 break; 254 case ELFCLASS64: 255 is_64 = true; 256 break; 257 default: 258 fprintf(stderr, "Unrecognised ELF class\n"); 259 err = -EINVAL; 260 goto out_free_relocs; 261 } 262 263 switch (ehdr32->e_ident[EI_DATA]) { 264 case ELFDATA2LSB: 265 is_be = false; 266 break; 267 case ELFDATA2MSB: 268 is_be = true; 269 break; 270 default: 271 fprintf(stderr, "Unrecognised ELF data encoding\n"); 272 err = -EINVAL; 273 goto out_free_relocs; 274 } 275 276 if (ehdr_field(e_type) != ET_EXEC) { 277 fprintf(stderr, "Input ELF is not an executable\n"); 278 printf("type 0x%lx\n", ehdr_field(e_type)); 279 err = -EINVAL; 280 goto out_free_relocs; 281 } 282 283 if (ehdr_field(e_machine) != EM_MIPS) { 284 fprintf(stderr, "Input ELF does not target MIPS\n"); 285 err = -EINVAL; 286 goto out_free_relocs; 287 } 288 289 phdr32 = elf + ehdr_field(e_phoff); 290 phdr64 = elf + ehdr_field(e_phoff); 291 shdr32 = elf + ehdr_field(e_shoff); 292 shdr64 = elf + ehdr_field(e_shoff); 293 shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset); 294 295 i_rel_shdr = UINT_MAX; 296 for (i = 0; i < ehdr_field(e_shnum); i++) { 297 sh_name = shstr(shdr_field(i, sh_name)); 298 299 if (!strcmp(sh_name, ".rel")) { 300 i_rel_shdr = i; 301 continue; 302 } 303 304 if (!strcmp(sh_name, ".text")) { 305 text_base = shdr_field(i, sh_addr); 306 continue; 307 } 308 } 309 if (i_rel_shdr == UINT_MAX) { 310 fprintf(stderr, "Unable to find .rel section\n"); 311 err = -EINVAL; 312 goto out_free_relocs; 313 } 314 if (!text_base) { 315 fprintf(stderr, "Unable to find .text base address\n"); 316 err = -EINVAL; 317 goto out_free_relocs; 318 } 319 320 rel_pfx = is_64 ? ".rela." : ".rel."; 321 322 for (i = 0; i < ehdr_field(e_shnum); i++) { 323 sh_type = shdr_field(i, sh_type); 324 if ((sh_type != SHT_REL) && (sh_type != SHT_RELA)) 325 continue; 326 327 sh_name = shstr(shdr_field(i, sh_name)); 328 if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) { 329 if (strcmp(sh_name, ".rel") && strcmp(sh_name, ".rel.dyn")) 330 fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name); 331 continue; 332 } 333 334 /* 335 * Skip reloc sections which either don't correspond to another 336 * section in the ELF, or whose corresponding section isn't 337 * loaded as part of the U-Boot binary (ie. doesn't have the 338 * alloc flags set). 339 */ 340 skip = true; 341 for (j = 0; j < ehdr_field(e_shnum); j++) { 342 if (strcmp(&sh_name[strlen(rel_pfx) - 1], shstr(shdr_field(j, sh_name)))) 343 continue; 344 345 skip = !(shdr_field(j, sh_flags) & SHF_ALLOC); 346 break; 347 } 348 if (skip) 349 continue; 350 351 sh_offset = shdr_field(i, sh_offset); 352 sh_entsize = shdr_field(i, sh_entsize); 353 sh_entries = shdr_field(i, sh_size) / sh_entsize; 354 355 if (sh_type == SHT_REL) { 356 if (is_64) { 357 fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n"); 358 err = -EINVAL; 359 goto out_free_relocs; 360 } else { 361 parse_fn = parse_mips32_rel; 362 } 363 } else { 364 if (is_64) { 365 parse_fn = parse_mips64_rela; 366 } else { 367 fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n"); 368 err = -EINVAL; 369 goto out_free_relocs; 370 } 371 } 372 373 for (j = 0; j < sh_entries; j++) { 374 err = parse_fn(elf + sh_offset + (j * sh_entsize)); 375 if (err) 376 goto out_free_relocs; 377 } 378 } 379 380 /* Sort relocs in ascending order of offset */ 381 qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs); 382 383 /* Make reloc offsets relative to their predecessor */ 384 for (i = relocs_idx - 1; i > 0; i--) 385 relocs[i].offset -= relocs[i - 1].offset; 386 387 /* Write the relocations to the .rel section */ 388 buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset); 389 for (i = 0; i < relocs_idx; i++) { 390 output_uint(&buf, relocs[i].type); 391 output_uint(&buf, relocs[i].offset >> 2); 392 } 393 394 /* Write a terminating R_MIPS_NONE (0) */ 395 output_uint(&buf, R_MIPS_NONE); 396 397 /* Ensure the relocs didn't overflow the .rel section */ 398 rel_size = shdr_field(i_rel_shdr, sh_size); 399 rel_actual_size = buf - buf_start; 400 if (rel_actual_size > rel_size) { 401 fprintf(stderr, "Relocs overflowed .rel section\n"); 402 return -ENOMEM; 403 } 404 405 /* Update the .rel section's size */ 406 set_shdr_field(i_rel_shdr, sh_size, rel_actual_size); 407 408 /* Shrink the PT_LOAD program header filesz (ie. shrink u-boot.bin) */ 409 for (i = 0; i < ehdr_field(e_phnum); i++) { 410 if (phdr_field(i, p_type) != PT_LOAD) 411 continue; 412 413 load_sz = phdr_field(i, p_filesz); 414 load_sz -= rel_size - rel_actual_size; 415 set_phdr_field(i, p_filesz, load_sz); 416 break; 417 } 418 419 /* Make sure data is written back to the file */ 420 err = msync(elf, st.st_size, MS_SYNC); 421 if (err) { 422 fprintf(stderr, "Failed to msync: %d\n", errno); 423 goto out_free_relocs; 424 } 425 426 out_free_relocs: 427 free(relocs); 428 munmap(elf, st.st_size); 429 out_close_fd: 430 close(fd); 431 out_ret: 432 return err; 433 } 434