tools/mips-relocs.c

   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 }