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