uboot/tools/mips-relocs.c
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   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
 100bool is_64, is_be;
 101uint64_t text_base;
 102
 103struct mips_reloc {
 104        uint8_t type;
 105        uint64_t offset;
 106} *relocs;
 107size_t relocs_sz, relocs_idx;
 108
 109static 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
 149static 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
 163static 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
 176static 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
 188static 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
 195int 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;
 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_Shdr *shdr32;
 206        Elf64_Shdr *shdr64;
 207        struct stat st;
 208        int err, fd;
 209        void *elf;
 210        bool skip;
 211
 212        fd = open(argv[1], O_RDWR);
 213        if (fd == -1) {
 214                fprintf(stderr, "Unable to open input file %s\n", argv[1]);
 215                err = errno;
 216                goto out_ret;
 217        }
 218
 219        err = fstat(fd, &st);
 220        if (err) {
 221                fprintf(stderr, "Unable to fstat() input file\n");
 222                goto out_close_fd;
 223        }
 224
 225        elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 226        if (elf == MAP_FAILED) {
 227                fprintf(stderr, "Unable to mmap() input file\n");
 228                err = errno;
 229                goto out_close_fd;
 230        }
 231
 232        ehdr32 = elf;
 233        ehdr64 = elf;
 234
 235        if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) {
 236                fprintf(stderr, "Input file is not an ELF\n");
 237                err = -EINVAL;
 238                goto out_free_relocs;
 239        }
 240
 241        if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) {
 242                fprintf(stderr, "Unrecognised ELF version\n");
 243                err = -EINVAL;
 244                goto out_free_relocs;
 245        }
 246
 247        switch (ehdr32->e_ident[EI_CLASS]) {
 248        case ELFCLASS32:
 249                is_64 = false;
 250                break;
 251        case ELFCLASS64:
 252                is_64 = true;
 253                break;
 254        default:
 255                fprintf(stderr, "Unrecognised ELF class\n");
 256                err = -EINVAL;
 257                goto out_free_relocs;
 258        }
 259
 260        switch (ehdr32->e_ident[EI_DATA]) {
 261        case ELFDATA2LSB:
 262                is_be = false;
 263                break;
 264        case ELFDATA2MSB:
 265                is_be = true;
 266                break;
 267        default:
 268                fprintf(stderr, "Unrecognised ELF data encoding\n");
 269                err = -EINVAL;
 270                goto out_free_relocs;
 271        }
 272
 273        if (ehdr_field(e_type) != ET_EXEC) {
 274                fprintf(stderr, "Input ELF is not an executable\n");
 275                printf("type 0x%lx\n", ehdr_field(e_type));
 276                err = -EINVAL;
 277                goto out_free_relocs;
 278        }
 279
 280        if (ehdr_field(e_machine) != EM_MIPS) {
 281                fprintf(stderr, "Input ELF does not target MIPS\n");
 282                err = -EINVAL;
 283                goto out_free_relocs;
 284        }
 285
 286        shdr32 = elf + ehdr_field(e_shoff);
 287        shdr64 = elf + ehdr_field(e_shoff);
 288        shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset);
 289
 290        i_rel_shdr = UINT_MAX;
 291        for (i = 0; i < ehdr_field(e_shnum); i++) {
 292                sh_name = shstr(shdr_field(i, sh_name));
 293
 294                if (!strcmp(sh_name, ".data.reloc")) {
 295                        i_rel_shdr = i;
 296                        continue;
 297                }
 298
 299                if (!strcmp(sh_name, ".text")) {
 300                        text_base = shdr_field(i, sh_addr);
 301                        continue;
 302                }
 303        }
 304        if (i_rel_shdr == UINT_MAX) {
 305                fprintf(stderr, "Unable to find .rel section\n");
 306                err = -EINVAL;
 307                goto out_free_relocs;
 308        }
 309        if (!text_base) {
 310                fprintf(stderr, "Unable to find .text base address\n");
 311                err = -EINVAL;
 312                goto out_free_relocs;
 313        }
 314
 315        rel_pfx = is_64 ? ".rela" : ".rel";
 316
 317        for (i = 0; i < ehdr_field(e_shnum); i++) {
 318                sh_type = shdr_field(i, sh_type);
 319                if ((sh_type != SHT_REL) && (sh_type != SHT_RELA))
 320                        continue;
 321
 322                sh_name = shstr(shdr_field(i, sh_name));
 323                if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) {
 324                        fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name);
 325                        continue;
 326                }
 327                if (!strcmp(sh_name, ".rel") || !strcmp(sh_name, ".rel.dyn"))
 328                        continue;
 329
 330                /*
 331                 * Skip reloc sections which either don't correspond to another
 332                 * section in the ELF, or whose corresponding section isn't
 333                 * loaded as part of the U-Boot binary (ie. doesn't have the
 334                 * alloc flags set).
 335                 */
 336                skip = true;
 337                for (j = 0; j < ehdr_field(e_shnum); j++) {
 338                        if (strcmp(&sh_name[strlen(rel_pfx)], shstr(shdr_field(j, sh_name))))
 339                                continue;
 340
 341                        skip = !(shdr_field(j, sh_flags) & SHF_ALLOC);
 342                        break;
 343                }
 344                if (skip)
 345                        continue;
 346
 347                sh_offset = shdr_field(i, sh_offset);
 348                sh_entsize = shdr_field(i, sh_entsize);
 349                sh_entries = shdr_field(i, sh_size) / sh_entsize;
 350
 351                if (sh_type == SHT_REL) {
 352                        if (is_64) {
 353                                fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n");
 354                                err = -EINVAL;
 355                                goto out_free_relocs;
 356                        } else {
 357                                parse_fn = parse_mips32_rel;
 358                        }
 359                } else {
 360                        if (is_64) {
 361                                parse_fn = parse_mips64_rela;
 362                        } else {
 363                                fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n");
 364                                err = -EINVAL;
 365                                goto out_free_relocs;
 366                        }
 367                }
 368
 369                for (j = 0; j < sh_entries; j++) {
 370                        err = parse_fn(elf + sh_offset + (j * sh_entsize));
 371                        if (err)
 372                                goto out_free_relocs;
 373                }
 374        }
 375
 376        /* Sort relocs in ascending order of offset */
 377        qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs);
 378
 379        /* Make reloc offsets relative to their predecessor */
 380        for (i = relocs_idx - 1; i > 0; i--)
 381                relocs[i].offset -= relocs[i - 1].offset;
 382
 383        /* Write the relocations to the .rel section */
 384        buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset);
 385        for (i = 0; i < relocs_idx; i++) {
 386                output_uint(&buf, relocs[i].type);
 387                output_uint(&buf, relocs[i].offset >> 2);
 388        }
 389
 390        /* Write a terminating R_MIPS_NONE (0) */
 391        output_uint(&buf, R_MIPS_NONE);
 392
 393        /* Ensure the relocs didn't overflow the .rel section */
 394        rel_size = shdr_field(i_rel_shdr, sh_size);
 395        rel_actual_size = buf - buf_start;
 396        if (rel_actual_size > rel_size) {
 397                fprintf(stderr, "Relocations overflow available space of 0x%lx (required 0x%lx)!\n",
 398                        rel_size, rel_actual_size);
 399                fprintf(stderr, "Please adjust CONFIG_MIPS_RELOCATION_TABLE_SIZE to at least 0x%lx\n",
 400                        (rel_actual_size + 0x100) & ~0xFF);
 401                err = -ENOMEM;
 402                goto out_free_relocs;
 403        }
 404
 405        /* Make sure data is written back to the file */
 406        err = msync(elf, st.st_size, MS_SYNC);
 407        if (err) {
 408                fprintf(stderr, "Failed to msync: %d\n", errno);
 409                goto out_free_relocs;
 410        }
 411
 412out_free_relocs:
 413        free(relocs);
 414        munmap(elf, st.st_size);
 415out_close_fd:
 416        close(fd);
 417out_ret:
 418        return err;
 419}
 420