diff options
Diffstat (limited to 'tools/mips-relocs.c')
| -rw-r--r-- | tools/mips-relocs.c | 426 |
1 files changed, 426 insertions, 0 deletions
diff --git a/tools/mips-relocs.c b/tools/mips-relocs.c new file mode 100644 index 0000000000..b690fa53c4 --- /dev/null +++ b/tools/mips-relocs.c @@ -0,0 +1,426 @@ +/* + * MIPS Relocation Data Generator + * + * Copyright (c) 2017 Imagination Technologies Ltd. + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include <elf.h> +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <stdio.h> +#include <stdlib.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <unistd.h> + +#include <asm/relocs.h> + +#define hdr_field(pfx, idx, field) ({ \ + uint64_t _val; \ + unsigned int _size; \ + \ + if (is_64) { \ + _val = pfx##hdr64[idx].field; \ + _size = sizeof(pfx##hdr64[0].field); \ + } else { \ + _val = pfx##hdr32[idx].field; \ + _size = sizeof(pfx##hdr32[0].field); \ + } \ + \ + switch (_size) { \ + case 1: \ + break; \ + case 2: \ + _val = is_be ? be16toh(_val) : le16toh(_val); \ + break; \ + case 4: \ + _val = is_be ? be32toh(_val) : le32toh(_val); \ + break; \ + case 8: \ + _val = is_be ? be64toh(_val) : le64toh(_val); \ + break; \ + } \ + \ + _val; \ +}) + +#define set_hdr_field(pfx, idx, field, val) ({ \ + uint64_t _val; \ + unsigned int _size; \ + \ + if (is_64) \ + _size = sizeof(pfx##hdr64[0].field); \ + else \ + _size = sizeof(pfx##hdr32[0].field); \ + \ + switch (_size) { \ + case 1: \ + _val = val; \ + break; \ + case 2: \ + _val = is_be ? htobe16(val) : htole16(val); \ + break; \ + case 4: \ + _val = is_be ? htobe32(val) : htole32(val); \ + break; \ + case 8: \ + _val = is_be ? htobe64(val) : htole64(val); \ + break; \ + } \ + \ + if (is_64) \ + pfx##hdr64[idx].field = _val; \ + else \ + pfx##hdr32[idx].field = _val; \ +}) + +#define ehdr_field(field) \ + hdr_field(e, 0, field) +#define phdr_field(idx, field) \ + hdr_field(p, idx, field) +#define shdr_field(idx, field) \ + hdr_field(s, idx, field) + +#define set_phdr_field(idx, field, val) \ + set_hdr_field(p, idx, field, val) +#define set_shdr_field(idx, field, val) \ + set_hdr_field(s, idx, field, val) + +#define shstr(idx) (&shstrtab[idx]) + +bool is_64, is_be; +uint64_t text_base; + +struct mips_reloc { + uint8_t type; + uint64_t offset; +} *relocs; +size_t relocs_sz, relocs_idx; + +static int add_reloc(unsigned int type, uint64_t off) +{ + struct mips_reloc *new; + size_t new_sz; + + switch (type) { + case R_MIPS_NONE: + case R_MIPS_LO16: + case R_MIPS_PC16: + case R_MIPS_HIGHER: + case R_MIPS_HIGHEST: + case R_MIPS_PC21_S2: + case R_MIPS_PC26_S2: + /* Skip these relocs */ + return 0; + + default: + break; + } + + if (relocs_idx == relocs_sz) { + new_sz = relocs_sz ? relocs_sz * 2 : 128; + new = realloc(relocs, new_sz * sizeof(*relocs)); + if (!new) { + fprintf(stderr, "Out of memory\n"); + return -ENOMEM; + } + + relocs = new; + relocs_sz = new_sz; + } + + relocs[relocs_idx++] = (struct mips_reloc){ + .type = type, + .offset = off, + }; + + return 0; +} + +static int parse_mips32_rel(const void *_rel) +{ + const Elf32_Rel *rel = _rel; + uint32_t off, type; + + off = is_be ? be32toh(rel->r_offset) : le32toh(rel->r_offset); + off -= text_base; + + type = is_be ? be32toh(rel->r_info) : le32toh(rel->r_info); + type = ELF32_R_TYPE(type); + + return add_reloc(type, off); +} + +static int parse_mips64_rela(const void *_rel) +{ + const Elf64_Rela *rel = _rel; + uint64_t off, type; + + off = is_be ? be64toh(rel->r_offset) : le64toh(rel->r_offset); + off -= text_base; + + type = rel->r_info >> (64 - 8); + + return add_reloc(type, off); +} + +static void output_uint(uint8_t **buf, uint64_t val) +{ + uint64_t tmp; + + do { + tmp = val & 0x7f; + val >>= 7; + tmp |= !!val << 7; + *(*buf)++ = tmp; + } while (val); +} + +static int compare_relocs(const void *a, const void *b) +{ + const struct mips_reloc *ra = a, *rb = b; + + return ra->offset - rb->offset; +} + +int main(int argc, char *argv[]) +{ + unsigned int i, j, i_rel_shdr, sh_type, sh_entsize, sh_entries; + size_t rel_size, rel_actual_size, load_sz; + const char *shstrtab, *sh_name, *rel_pfx; + int (*parse_fn)(const void *rel); + uint8_t *buf_start, *buf; + const Elf32_Ehdr *ehdr32; + const Elf64_Ehdr *ehdr64; + uintptr_t sh_offset; + Elf32_Phdr *phdr32; + Elf64_Phdr *phdr64; + Elf32_Shdr *shdr32; + Elf64_Shdr *shdr64; + struct stat st; + int err, fd; + void *elf; + bool skip; + + fd = open(argv[1], O_RDWR); + if (fd == -1) { + fprintf(stderr, "Unable to open input file %s\n", argv[1]); + err = errno; + goto out_ret; + } + + err = fstat(fd, &st); + if (err) { + fprintf(stderr, "Unable to fstat() input file\n"); + goto out_close_fd; + } + + elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + if (elf == MAP_FAILED) { + fprintf(stderr, "Unable to mmap() input file\n"); + err = errno; + goto out_close_fd; + } + + ehdr32 = elf; + ehdr64 = elf; + + if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) { + fprintf(stderr, "Input file is not an ELF\n"); + err = -EINVAL; + goto out_free_relocs; + } + + if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) { + fprintf(stderr, "Unrecognised ELF version\n"); + err = -EINVAL; + goto out_free_relocs; + } + + switch (ehdr32->e_ident[EI_CLASS]) { + case ELFCLASS32: + is_64 = false; + break; + case ELFCLASS64: + is_64 = true; + break; + default: + fprintf(stderr, "Unrecognised ELF class\n"); + err = -EINVAL; + goto out_free_relocs; + } + + switch (ehdr32->e_ident[EI_DATA]) { + case ELFDATA2LSB: + is_be = false; + break; + case ELFDATA2MSB: + is_be = true; + break; + default: + fprintf(stderr, "Unrecognised ELF data encoding\n"); + err = -EINVAL; + goto out_free_relocs; + } + + if (ehdr_field(e_type) != ET_EXEC) { + fprintf(stderr, "Input ELF is not an executable\n"); + printf("type 0x%lx\n", ehdr_field(e_type)); + err = -EINVAL; + goto out_free_relocs; + } + + if (ehdr_field(e_machine) != EM_MIPS) { + fprintf(stderr, "Input ELF does not target MIPS\n"); + err = -EINVAL; + goto out_free_relocs; + } + + phdr32 = elf + ehdr_field(e_phoff); + phdr64 = elf + ehdr_field(e_phoff); + shdr32 = elf + ehdr_field(e_shoff); + shdr64 = elf + ehdr_field(e_shoff); + shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset); + + i_rel_shdr = UINT_MAX; + for (i = 0; i < ehdr_field(e_shnum); i++) { + sh_name = shstr(shdr_field(i, sh_name)); + + if (!strcmp(sh_name, ".rel")) { + i_rel_shdr = i; + continue; + } + + if (!strcmp(sh_name, ".text")) { + text_base = shdr_field(i, sh_addr); + continue; + } + } + if (i_rel_shdr == UINT_MAX) { + fprintf(stderr, "Unable to find .rel section\n"); + err = -EINVAL; + goto out_free_relocs; + } + if (!text_base) { + fprintf(stderr, "Unable to find .text base address\n"); + err = -EINVAL; + goto out_free_relocs; + } + + rel_pfx = is_64 ? ".rela." : ".rel."; + + for (i = 0; i < ehdr_field(e_shnum); i++) { + sh_type = shdr_field(i, sh_type); + if ((sh_type != SHT_REL) && (sh_type != SHT_RELA)) + continue; + + sh_name = shstr(shdr_field(i, sh_name)); + if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) { + if (strcmp(sh_name, ".rel") && strcmp(sh_name, ".rel.dyn")) + fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name); + continue; + } + + /* + * Skip reloc sections which either don't correspond to another + * section in the ELF, or whose corresponding section isn't + * loaded as part of the U-Boot binary (ie. doesn't have the + * alloc flags set). + */ + skip = true; + for (j = 0; j < ehdr_field(e_shnum); j++) { + if (strcmp(&sh_name[strlen(rel_pfx) - 1], shstr(shdr_field(j, sh_name)))) + continue; + + skip = !(shdr_field(j, sh_flags) & SHF_ALLOC); + break; + } + if (skip) + continue; + + sh_offset = shdr_field(i, sh_offset); + sh_entsize = shdr_field(i, sh_entsize); + sh_entries = shdr_field(i, sh_size) / sh_entsize; + + if (sh_type == SHT_REL) { + if (is_64) { + fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n"); + err = -EINVAL; + goto out_free_relocs; + } else { + parse_fn = parse_mips32_rel; + } + } else { + if (is_64) { + parse_fn = parse_mips64_rela; + } else { + fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n"); + err = -EINVAL; + goto out_free_relocs; + } + } + + for (j = 0; j < sh_entries; j++) { + err = parse_fn(elf + sh_offset + (j * sh_entsize)); + if (err) + goto out_free_relocs; + } + } + + /* Sort relocs in ascending order of offset */ + qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs); + + /* Make reloc offsets relative to their predecessor */ + for (i = relocs_idx - 1; i > 0; i--) + relocs[i].offset -= relocs[i - 1].offset; + + /* Write the relocations to the .rel section */ + buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset); + for (i = 0; i < relocs_idx; i++) { + output_uint(&buf, relocs[i].type); + output_uint(&buf, relocs[i].offset >> 2); + } + + /* Write a terminating R_MIPS_NONE (0) */ + output_uint(&buf, R_MIPS_NONE); + + /* Ensure the relocs didn't overflow the .rel section */ + rel_size = shdr_field(i_rel_shdr, sh_size); + rel_actual_size = buf - buf_start; + if (rel_actual_size > rel_size) { + fprintf(stderr, "Relocs overflowed .rel section\n"); + return -ENOMEM; + } + + /* Update the .rel section's size */ + set_shdr_field(i_rel_shdr, sh_size, rel_actual_size); + + /* Shrink the PT_LOAD program header filesz (ie. shrink u-boot.bin) */ + for (i = 0; i < ehdr_field(e_phnum); i++) { + if (phdr_field(i, p_type) != PT_LOAD) + continue; + + load_sz = phdr_field(i, p_filesz); + load_sz -= rel_size - rel_actual_size; + set_phdr_field(i, p_filesz, load_sz); + break; + } + + /* Make sure data is written back to the file */ + err = msync(elf, st.st_size, MS_SYNC); + if (err) { + fprintf(stderr, "Failed to msync: %d\n", errno); + goto out_free_relocs; + } + +out_free_relocs: + free(relocs); + munmap(elf, st.st_size); +out_close_fd: + close(fd); +out_ret: + return err; +} |