tools/prelink-riscv.inc

   1 /*
   2  * Copyright (C) 2017 Andes Technology
   3  * Chih-Mao Chen <cmchen@andestech.com>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  *
   7  * Statically process runtime relocations on RISC-V ELF images
   8  * so that it can be directly executed when loaded at LMA
   9  * without fixup. Both RV32 and RV64 are supported.
  10  */
  11
  12 #define CONCAT_IMPL(x, y) x##y
  13 #define CONCAT(x, y) CONCAT_IMPL(x, y)
  14 #define CONCAT3(x, y, z) CONCAT(CONCAT(x, y), z)
  15
  16 #define prelink_nn      CONCAT(prelink, PRELINK_INC_BITS)
  17 #define uintnn_t        CONCAT3(uint, PRELINK_INC_BITS, _t)
  18 #define get_offset_nn   CONCAT(get_offset_, PRELINK_INC_BITS)
  19 #define Elf_Ehdr        CONCAT3(Elf, PRELINK_INC_BITS, _Ehdr)
  20 #define Elf_Phdr        CONCAT3(Elf, PRELINK_INC_BITS, _Phdr)
  21 #define Elf_Rela        CONCAT3(Elf, PRELINK_INC_BITS, _Rela)
  22 #define Elf_Sym         CONCAT3(Elf, PRELINK_INC_BITS, _Sym)
  23 #define Elf_Dyn         CONCAT3(Elf, PRELINK_INC_BITS, _Dyn)
  24 #define Elf_Addr        CONCAT3(Elf, PRELINK_INC_BITS, _Addr)
  25 #define ELF_R_TYPE      CONCAT3(ELF, PRELINK_INC_BITS, _R_TYPE)
  26 #define ELF_R_SYM       CONCAT3(ELF, PRELINK_INC_BITS, _R_SYM)
  27
  28 static void* get_offset_nn (void* data, Elf_Phdr* phdrs, size_t phnum, Elf_Addr addr)
  29 {
  30         Elf_Phdr *p;
  31
  32         for (p = phdrs; p < phdrs + phnum; ++p)
  33                 if (p->p_vaddr <= addr && p->p_vaddr + p->p_memsz > addr)
  34                         return data + p->p_offset + (addr - p->p_vaddr);
  35
  36         return NULL;
  37 }
  38
  39 static void prelink_nn(void *data)
  40 {
  41         Elf_Ehdr *ehdr = data;
  42         Elf_Phdr *p;
  43         Elf_Dyn *dyn;
  44         Elf_Rela *r;
  45
  46         if (ehdr->e_machine != EM_RISCV)
  47                 die("Machine type is not RISC-V");
  48
  49         Elf_Phdr *phdrs = data + ehdr->e_phoff;
  50
  51         Elf_Dyn *dyns = NULL;
  52         for (p = phdrs; p < phdrs + ehdr->e_phnum; ++p) {
  53                 if (p->p_type == PT_DYNAMIC) {
  54                         dyns = data + p->p_offset;
  55                         break;
  56                 }
  57         }
  58
  59         if (dyns == NULL)
  60                 die("No dynamic section found");
  61
  62         Elf_Rela *rela_dyn = NULL;
  63         size_t rela_count = 0;
  64         Elf_Sym *dynsym = NULL;
  65         for (dyn = dyns;; ++dyn) {
  66                 if (dyn->d_tag == DT_NULL)
  67                         break;
  68                 else if (dyn->d_tag == DT_RELA)
  69                         rela_dyn = get_offset_nn(data, phdrs, ehdr->e_phnum, + dyn->d_un.d_ptr);
  70                 else if (dyn->d_tag == DT_RELASZ)
  71                         rela_count = dyn->d_un.d_val / sizeof(Elf_Rela);
  72                 else if (dyn->d_tag == DT_SYMTAB)
  73                         dynsym = get_offset_nn(data, phdrs, ehdr->e_phnum, + dyn->d_un.d_ptr);
  74
  75         }
  76
  77         if (rela_dyn == NULL)
  78                 die("No .rela.dyn found");
  79
  80         if (dynsym == NULL)
  81                 die("No .dynsym found");
  82
  83         for (r = rela_dyn; r < rela_dyn + rela_count; ++r) {
  84                 void* buf = get_offset_nn(data, phdrs, ehdr->e_phnum, r->r_offset);
  85
  86                 if (buf == NULL)
  87                         continue;
  88
  89                 if (ELF_R_TYPE(r->r_info) == R_RISCV_RELATIVE)
  90                         *((uintnn_t*) buf) = r->r_addend;
  91                 else if (ELF_R_TYPE(r->r_info) == R_RISCV_32)
  92                         *((uint32_t*) buf) = dynsym[ELF_R_SYM(r->r_info)].st_value;
  93                 else if (ELF_R_TYPE(r->r_info) == R_RISCV_64)
  94                         *((uint64_t*) buf) = dynsym[ELF_R_SYM(r->r_info)].st_value;
  95         }
  96 }
  97
  98 #undef prelink_nn
  99 #undef uintnn_t
 100 #undef get_offset_nn
 101 #undef Elf_Ehdr
 102 #undef Elf_Phdr
 103 #undef Elf_Rela
 104 #undef Elf_Sym
 105 #undef Elf_Dyn
 106 #undef Elf_Addr
 107 #undef ELF_R_TYPE
 108 #undef ELF_R_SYM
 109
 110 #undef CONCAT_IMPL
 111 #undef CONCAT
 112 #undef CONCAT3