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// SPDX-License-Identifier: GPL-2.0+
* Copyright (C) 2017 Andes Technology
* Chih-Mao Chen <>
* Statically process runtime relocations on RISC-V ELF images
* so that it can be directly executed when loaded at LMA
* without fixup. Both RV32 and RV64 are supported.
#define CONCAT_IMPL(x, y) x##y
#define CONCAT(x, y) CONCAT_IMPL(x, y)
#define CONCAT3(x, y, z) CONCAT(CONCAT(x, y), z)
#define prelink_nn CONCAT(prelink, PRELINK_INC_BITS)
#define uintnn_t CONCAT3(uint, PRELINK_INC_BITS, _t)
#define get_offset_nn CONCAT(get_offset_, PRELINK_INC_BITS)
#define Elf_Ehdr CONCAT3(Elf, PRELINK_INC_BITS, _Ehdr)
#define Elf_Phdr CONCAT3(Elf, PRELINK_INC_BITS, _Phdr)
#define Elf_Rela CONCAT3(Elf, PRELINK_INC_BITS, _Rela)
#define Elf_Sym CONCAT3(Elf, PRELINK_INC_BITS, _Sym)
#define Elf_Dyn CONCAT3(Elf, PRELINK_INC_BITS, _Dyn)
#define Elf_Addr CONCAT3(Elf, PRELINK_INC_BITS, _Addr)
static void* get_offset_nn (void* data, Elf_Phdr* phdrs, size_t phnum, Elf_Addr addr)
Elf_Phdr *p;
for (p = phdrs; p < phdrs + phnum; ++p)
if (p->p_vaddr <= addr && p->p_vaddr + p->p_memsz > addr)
return data + p->p_offset + (addr - p->p_vaddr);
return NULL;
static void prelink_nn(void *data)
Elf_Ehdr *ehdr = data;
Elf_Phdr *p;
Elf_Dyn *dyn;
Elf_Rela *r;
if (ehdr->e_machine != EM_RISCV)
die("Machine type is not RISC-V");
Elf_Phdr *phdrs = data + ehdr->e_phoff;
Elf_Dyn *dyns = NULL;
for (p = phdrs; p < phdrs + ehdr->e_phnum; ++p) {
if (p->p_type == PT_DYNAMIC) {
dyns = data + p->p_offset;
if (dyns == NULL)
die("No dynamic section found");
Elf_Rela *rela_dyn = NULL;
size_t rela_count = 0;
Elf_Sym *dynsym = NULL;
for (dyn = dyns;; ++dyn) {
if (dyn->d_tag == DT_NULL)
else if (dyn->d_tag == DT_RELA)
rela_dyn = get_offset_nn(data, phdrs, ehdr->e_phnum, + dyn->d_un.d_ptr);
else if (dyn->d_tag == DT_RELASZ)
rela_count = dyn->d_un.d_val / sizeof(Elf_Rela);
else if (dyn->d_tag == DT_SYMTAB)
dynsym = get_offset_nn(data, phdrs, ehdr->e_phnum, + dyn->d_un.d_ptr);
if (rela_dyn == NULL)
die("No .rela.dyn found");
if (dynsym == NULL)
die("No .dynsym found");
for (r = rela_dyn; r < rela_dyn + rela_count; ++r) {
void* buf = get_offset_nn(data, phdrs, ehdr->e_phnum, r->r_offset);
if (buf == NULL)
if (ELF_R_TYPE(r->r_info) == R_RISCV_RELATIVE)
*((uintnn_t*) buf) = r->r_addend;
else if (ELF_R_TYPE(r->r_info) == R_RISCV_32)
*((uint32_t*) buf) = dynsym[ELF_R_SYM(r->r_info)].st_value;
else if (ELF_R_TYPE(r->r_info) == R_RISCV_64)
*((uint64_t*) buf) = dynsym[ELF_R_SYM(r->r_info)].st_value;
#undef prelink_nn
#undef uintnn_t
#undef get_offset_nn
#undef Elf_Ehdr
#undef Elf_Phdr
#undef Elf_Rela
#undef Elf_Sym
#undef Elf_Dyn
#undef Elf_Addr
#undef ELF_R_TYPE
#undef ELF_R_SYM
#undef CONCAT
#undef CONCAT3