tools/prelink-riscv.inc

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