// SPDX-License-Identifier: GPL-2.0+
/*
* MIPS Relocation Data Generator
*
* Copyright (c) 2017 Imagination Technologies Ltd.
*/
#include <assert.h>
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdbool.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; \
default: \
/* We should never reach here */ \
_val = 0; \
assert(0); \
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;
}