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 <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 }