tools/mips-relocs.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * MIPS Relocation Data Generator
   4  *
   5  * Copyright (c) 2017 Imagination Technologies Ltd.
   6  */
   7
   8 #include <assert.h>
   9 #include <elf.h>
  10 #include <errno.h>
  11 #include <fcntl.h>
  12 #include <limits.h>
  13 #include <stdbool.h>
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <sys/mman.h>
  17 #include <sys/stat.h>
  18 #include <unistd.h>
  19
  20 #include <asm/relocs.h>
  21
  22 #define hdr_field(pfx, idx, field) ({                           \
  23         uint64_t _val;                                          \
  24         unsigned int _size;                                     \
  25                                                                 \
  26         if (is_64) {                                            \
  27                 _val = pfx##hdr64[idx].field;                   \
  28                 _size = sizeof(pfx##hdr64[0].field);            \
  29         } else {                                                \
  30                 _val = pfx##hdr32[idx].field;                   \
  31                 _size = sizeof(pfx##hdr32[0].field);            \
  32         }                                                       \
  33                                                                 \
  34         switch (_size) {                                        \
  35         case 1:                                                 \
  36                 break;                                          \
  37         case 2:                                                 \
  38                 _val = is_be ? be16toh(_val) : le16toh(_val);   \
  39                 break;                                          \
  40         case 4:                                                 \
  41                 _val = is_be ? be32toh(_val) : le32toh(_val);   \
  42                 break;                                          \
  43         case 8:                                                 \
  44                 _val = is_be ? be64toh(_val) : le64toh(_val);   \
  45                 break;                                          \
  46         }                                                       \
  47                                                                 \
  48         _val;                                                   \
  49 })
  50
  51 #define set_hdr_field(pfx, idx, field, val) ({                  \
  52         uint64_t _val;                                          \
  53         unsigned int _size;                                     \
  54                                                                 \
  55         if (is_64)                                              \
  56                 _size = sizeof(pfx##hdr64[0].field);            \
  57         else                                                    \
  58                 _size = sizeof(pfx##hdr32[0].field);            \
  59                                                                 \
  60         switch (_size) {                                        \
  61         case 1:                                                 \
  62                 _val = val;                                     \
  63                 break;                                          \
  64         case 2:                                                 \
  65                 _val = is_be ? htobe16(val) : htole16(val);     \
  66                 break;                                          \
  67         case 4:                                                 \
  68                 _val = is_be ? htobe32(val) : htole32(val);     \
  69                 break;                                          \
  70         case 8:                                                 \
  71                 _val = is_be ? htobe64(val) : htole64(val);     \
  72                 break;                                          \
  73         default:                                                \
  74                 /* We should never reach here */                \
  75                 _val = 0;                                       \
  76                 assert(0);                                      \
  77                 break;                                          \
  78         }                                                       \
  79                                                                 \
  80         if (is_64)                                              \
  81                 pfx##hdr64[idx].field = _val;                   \
  82         else                                                    \
  83                 pfx##hdr32[idx].field = _val;                   \
  84 })
  85
  86 #define ehdr_field(field) \
  87         hdr_field(e, 0, field)
  88 #define phdr_field(idx, field) \
  89         hdr_field(p, idx, field)
  90 #define shdr_field(idx, field) \
  91         hdr_field(s, idx, field)
  92
  93 #define set_phdr_field(idx, field, val) \
  94         set_hdr_field(p, idx, field, val)
  95 #define set_shdr_field(idx, field, val) \
  96         set_hdr_field(s, idx, field, val)
  97
  98 #define shstr(idx) (&shstrtab[idx])
  99
 100 bool is_64, is_be;
 101 uint64_t text_base;
 102
 103 struct mips_reloc {
 104         uint8_t type;
 105         uint64_t offset;
 106 } *relocs;
 107 size_t relocs_sz, relocs_idx;
 108
 109 static int add_reloc(unsigned int type, uint64_t off)
 110 {
 111         struct mips_reloc *new;
 112         size_t new_sz;
 113
 114         switch (type) {
 115         case R_MIPS_NONE:
 116         case R_MIPS_LO16:
 117         case R_MIPS_PC16:
 118         case R_MIPS_HIGHER:
 119         case R_MIPS_HIGHEST:
 120         case R_MIPS_PC21_S2:
 121         case R_MIPS_PC26_S2:
 122                 /* Skip these relocs */
 123                 return 0;
 124
 125         default:
 126                 break;
 127         }
 128
 129         if (relocs_idx == relocs_sz) {
 130                 new_sz = relocs_sz ? relocs_sz * 2 : 128;
 131                 new = realloc(relocs, new_sz * sizeof(*relocs));
 132                 if (!new) {
 133                         fprintf(stderr, "Out of memory\n");
 134                         return -ENOMEM;
 135                 }
 136
 137                 relocs = new;
 138                 relocs_sz = new_sz;
 139         }
 140
 141         relocs[relocs_idx++] = (struct mips_reloc){
 142                 .type = type,
 143                 .offset = off,
 144         };
 145
 146         return 0;
 147 }
 148
 149 static int parse_mips32_rel(const void *_rel)
 150 {
 151         const Elf32_Rel *rel = _rel;
 152         uint32_t off, type;
 153
 154         off = is_be ? be32toh(rel->r_offset) : le32toh(rel->r_offset);
 155         off -= text_base;
 156
 157         type = is_be ? be32toh(rel->r_info) : le32toh(rel->r_info);
 158         type = ELF32_R_TYPE(type);
 159
 160         return add_reloc(type, off);
 161 }
 162
 163 static int parse_mips64_rela(const void *_rel)
 164 {
 165         const Elf64_Rela *rel = _rel;
 166         uint64_t off, type;
 167
 168         off = is_be ? be64toh(rel->r_offset) : le64toh(rel->r_offset);
 169         off -= text_base;
 170
 171         type = rel->r_info >> (64 - 8);
 172
 173         return add_reloc(type, off);
 174 }
 175
 176 static void output_uint(uint8_t **buf, uint64_t val)
 177 {
 178         uint64_t tmp;
 179
 180         do {
 181                 tmp = val & 0x7f;
 182                 val >>= 7;
 183                 tmp |= !!val << 7;
 184                 *(*buf)++ = tmp;
 185         } while (val);
 186 }
 187
 188 static int compare_relocs(const void *a, const void *b)
 189 {
 190         const struct mips_reloc *ra = a, *rb = b;
 191
 192         return ra->offset - rb->offset;
 193 }
 194
 195 int main(int argc, char *argv[])
 196 {
 197         unsigned int i, j, i_rel_shdr, sh_type, sh_entsize, sh_entries;
 198         size_t rel_size, rel_actual_size, load_sz;
 199         const char *shstrtab, *sh_name, *rel_pfx;
 200         int (*parse_fn)(const void *rel);
 201         uint8_t *buf_start, *buf;
 202         const Elf32_Ehdr *ehdr32;
 203         const Elf64_Ehdr *ehdr64;
 204         uintptr_t sh_offset;
 205         Elf32_Phdr *phdr32;
 206         Elf64_Phdr *phdr64;
 207         Elf32_Shdr *shdr32;
 208         Elf64_Shdr *shdr64;
 209         struct stat st;
 210         int err, fd;
 211         void *elf;
 212         bool skip;
 213
 214         fd = open(argv[1], O_RDWR);
 215         if (fd == -1) {
 216                 fprintf(stderr, "Unable to open input file %s\n", argv[1]);
 217                 err = errno;
 218                 goto out_ret;
 219         }
 220
 221         err = fstat(fd, &st);
 222         if (err) {
 223                 fprintf(stderr, "Unable to fstat() input file\n");
 224                 goto out_close_fd;
 225         }
 226
 227         elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 228         if (elf == MAP_FAILED) {
 229                 fprintf(stderr, "Unable to mmap() input file\n");
 230                 err = errno;
 231                 goto out_close_fd;
 232         }
 233
 234         ehdr32 = elf;
 235         ehdr64 = elf;
 236
 237         if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) {
 238                 fprintf(stderr, "Input file is not an ELF\n");
 239                 err = -EINVAL;
 240                 goto out_free_relocs;
 241         }
 242
 243         if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) {
 244                 fprintf(stderr, "Unrecognised ELF version\n");
 245                 err = -EINVAL;
 246                 goto out_free_relocs;
 247         }
 248
 249         switch (ehdr32->e_ident[EI_CLASS]) {
 250         case ELFCLASS32:
 251                 is_64 = false;
 252                 break;
 253         case ELFCLASS64:
 254                 is_64 = true;
 255                 break;
 256         default:
 257                 fprintf(stderr, "Unrecognised ELF class\n");
 258                 err = -EINVAL;
 259                 goto out_free_relocs;
 260         }
 261
 262         switch (ehdr32->e_ident[EI_DATA]) {
 263         case ELFDATA2LSB:
 264                 is_be = false;
 265                 break;
 266         case ELFDATA2MSB:
 267                 is_be = true;
 268                 break;
 269         default:
 270                 fprintf(stderr, "Unrecognised ELF data encoding\n");
 271                 err = -EINVAL;
 272                 goto out_free_relocs;
 273         }
 274
 275         if (ehdr_field(e_type) != ET_EXEC) {
 276                 fprintf(stderr, "Input ELF is not an executable\n");
 277                 printf("type 0x%lx\n", ehdr_field(e_type));
 278                 err = -EINVAL;
 279                 goto out_free_relocs;
 280         }
 281
 282         if (ehdr_field(e_machine) != EM_MIPS) {
 283                 fprintf(stderr, "Input ELF does not target MIPS\n");
 284                 err = -EINVAL;
 285                 goto out_free_relocs;
 286         }
 287
 288         phdr32 = elf + ehdr_field(e_phoff);
 289         phdr64 = elf + ehdr_field(e_phoff);
 290         shdr32 = elf + ehdr_field(e_shoff);
 291         shdr64 = elf + ehdr_field(e_shoff);
 292         shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset);
 293
 294         i_rel_shdr = UINT_MAX;
 295         for (i = 0; i < ehdr_field(e_shnum); i++) {
 296                 sh_name = shstr(shdr_field(i, sh_name));
 297
 298                 if (!strcmp(sh_name, ".rel")) {
 299                         i_rel_shdr = i;
 300                         continue;
 301                 }
 302
 303                 if (!strcmp(sh_name, ".text")) {
 304                         text_base = shdr_field(i, sh_addr);
 305                         continue;
 306                 }
 307         }
 308         if (i_rel_shdr == UINT_MAX) {
 309                 fprintf(stderr, "Unable to find .rel section\n");
 310                 err = -EINVAL;
 311                 goto out_free_relocs;
 312         }
 313         if (!text_base) {
 314                 fprintf(stderr, "Unable to find .text base address\n");
 315                 err = -EINVAL;
 316                 goto out_free_relocs;
 317         }
 318
 319         rel_pfx = is_64 ? ".rela." : ".rel.";
 320
 321         for (i = 0; i < ehdr_field(e_shnum); i++) {
 322                 sh_type = shdr_field(i, sh_type);
 323                 if ((sh_type != SHT_REL) && (sh_type != SHT_RELA))
 324                         continue;
 325
 326                 sh_name = shstr(shdr_field(i, sh_name));
 327                 if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) {
 328                         if (strcmp(sh_name, ".rel") && strcmp(sh_name, ".rel.dyn"))
 329                                 fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name);
 330                         continue;
 331                 }
 332
 333                 /*
 334                  * Skip reloc sections which either don't correspond to another
 335                  * section in the ELF, or whose corresponding section isn't
 336                  * loaded as part of the U-Boot binary (ie. doesn't have the
 337                  * alloc flags set).
 338                  */
 339                 skip = true;
 340                 for (j = 0; j < ehdr_field(e_shnum); j++) {
 341                         if (strcmp(&sh_name[strlen(rel_pfx) - 1], shstr(shdr_field(j, sh_name))))
 342                                 continue;
 343
 344                         skip = !(shdr_field(j, sh_flags) & SHF_ALLOC);
 345                         break;
 346                 }
 347                 if (skip)
 348                         continue;
 349
 350                 sh_offset = shdr_field(i, sh_offset);
 351                 sh_entsize = shdr_field(i, sh_entsize);
 352                 sh_entries = shdr_field(i, sh_size) / sh_entsize;
 353
 354                 if (sh_type == SHT_REL) {
 355                         if (is_64) {
 356                                 fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n");
 357                                 err = -EINVAL;
 358                                 goto out_free_relocs;
 359                         } else {
 360                                 parse_fn = parse_mips32_rel;
 361                         }
 362                 } else {
 363                         if (is_64) {
 364                                 parse_fn = parse_mips64_rela;
 365                         } else {
 366                                 fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n");
 367                                 err = -EINVAL;
 368                                 goto out_free_relocs;
 369                         }
 370                 }
 371
 372                 for (j = 0; j < sh_entries; j++) {
 373                         err = parse_fn(elf + sh_offset + (j * sh_entsize));
 374                         if (err)
 375                                 goto out_free_relocs;
 376                 }
 377         }
 378
 379         /* Sort relocs in ascending order of offset */
 380         qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs);
 381
 382         /* Make reloc offsets relative to their predecessor */
 383         for (i = relocs_idx - 1; i > 0; i--)
 384                 relocs[i].offset -= relocs[i - 1].offset;
 385
 386         /* Write the relocations to the .rel section */
 387         buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset);
 388         for (i = 0; i < relocs_idx; i++) {
 389                 output_uint(&buf, relocs[i].type);
 390                 output_uint(&buf, relocs[i].offset >> 2);
 391         }
 392
 393         /* Write a terminating R_MIPS_NONE (0) */
 394         output_uint(&buf, R_MIPS_NONE);
 395
 396         /* Ensure the relocs didn't overflow the .rel section */
 397         rel_size = shdr_field(i_rel_shdr, sh_size);
 398         rel_actual_size = buf - buf_start;
 399         if (rel_actual_size > rel_size) {
 400                 fprintf(stderr, "Relocs overflowed .rel section\n");
 401                 return -ENOMEM;
 402         }
 403
 404         /* Update the .rel section's size */
 405         set_shdr_field(i_rel_shdr, sh_size, rel_actual_size);
 406
 407         /* Shrink the PT_LOAD program header filesz (ie. shrink u-boot.bin) */
 408         for (i = 0; i < ehdr_field(e_phnum); i++) {
 409                 if (phdr_field(i, p_type) != PT_LOAD)
 410                         continue;
 411
 412                 load_sz = phdr_field(i, p_filesz);
 413                 load_sz -= rel_size - rel_actual_size;
 414                 set_phdr_field(i, p_filesz, load_sz);
 415                 break;
 416         }
 417
 418         /* Make sure data is written back to the file */
 419         err = msync(elf, st.st_size, MS_SYNC);
 420         if (err) {
 421                 fprintf(stderr, "Failed to msync: %d\n", errno);
 422                 goto out_free_relocs;
 423         }
 424
 425 out_free_relocs:
 426         free(relocs);
 427         munmap(elf, st.st_size);
 428 out_close_fd:
 429         close(fd);
 430 out_ret:
 431         return err;
 432 }