bfd/elf32-wasm32.c

   1 /* 32-bit ELF for the WebAssembly target
   2    Copyright (C) 2017-2018 Free Software Foundation, Inc.
   3
   4    This file is part of BFD, the Binary File Descriptor library.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 51 Franklin Street - Fifth Floor,
  19    Boston, MA 02110-1301, USA.  */
  20
  21 #include "sysdep.h"
  22 #include "bfd.h"
  23 #include "libbfd.h"
  24 #include "elf-bfd.h"
  25 #include "bfd_stdint.h"
  26 #include "libiberty.h"
  27 #include "elf/wasm32.h"
  28
  29 static reloc_howto_type elf32_wasm32_howto_table[] =
  30 {
  31   HOWTO (R_WASM32_NONE,         /* type */
  32          0,                     /* rightshift */
  33          3,                     /* size (0 = byte, 1 = short, 2 = long) */
  34          0,                     /* bitsize */
  35          FALSE,                 /* pc_relative */
  36          0,                     /* bitpos */
  37          complain_overflow_dont,/* complain_on_overflow */
  38          bfd_elf_generic_reloc, /* special_function */
  39          "R_WASM32_NONE",       /* name */
  40          FALSE,                 /* partial_inplace */
  41          0,                     /* src_mask */
  42          0,                     /* dst_mask */
  43          FALSE),                /* pcrel_offset */
  44
  45   /* 32 bit absolute */
  46   HOWTO (R_WASM32_32,           /* type */
  47          0,                     /* rightshift */
  48          2,                     /* size (0 = byte, 1 = short, 2 = long) */
  49          32,                    /* bitsize */
  50          FALSE,                 /* pc_relative */
  51          0,                     /* bitpos */
  52          complain_overflow_bitfield,/* complain_on_overflow */
  53          bfd_elf_generic_reloc, /* special_function */
  54          "R_WASM32_32", /* name */
  55          FALSE,                 /* partial_inplace */
  56          0xffffffff,            /* src_mask */
  57          0xffffffff,            /* dst_mask */
  58          FALSE),                /* pcrel_offset */
  59 };
  60
  61 /* Look up the relocation CODE.  */
  62
  63 static reloc_howto_type *
  64 elf32_wasm32_reloc_type_lookup (bfd *abfd ATTRIBUTE_UNUSED,
  65                                 bfd_reloc_code_real_type code)
  66 {
  67   switch (code)
  68     {
  69     case BFD_RELOC_NONE:
  70       return &elf32_wasm32_howto_table[R_WASM32_NONE];
  71     case BFD_RELOC_32:
  72       return &elf32_wasm32_howto_table[R_WASM32_32];
  73     default:
  74       break;
  75     }
  76
  77   return NULL;
  78 }
  79
  80 /* Look up the relocation R_NAME.  */
  81
  82 static reloc_howto_type *
  83 elf32_wasm32_reloc_name_lookup (bfd *abfd ATTRIBUTE_UNUSED,
  84                                 const char *r_name)
  85 {
  86   unsigned int i;
  87
  88   for (i = 0; i < ARRAY_SIZE (elf32_wasm32_howto_table); i++)
  89     if (elf32_wasm32_howto_table[i].name != NULL
  90         && strcasecmp (elf32_wasm32_howto_table[i].name, r_name) == 0)
  91       return &elf32_wasm32_howto_table[i];
  92
  93   return NULL;
  94 }
  95
  96 /* Look up the relocation R_TYPE.  */
  97
  98 static reloc_howto_type *
  99 elf32_wasm32_rtype_to_howto (bfd *abfd, unsigned r_type)
 100 {
 101   unsigned int i = r_type;
 102
 103   if (i >= ARRAY_SIZE (elf32_wasm32_howto_table))
 104     {
 105       /* xgettext:c-format */
 106       _bfd_error_handler (_("%pB: unsupported relocation type %#x"),
 107                           abfd, r_type);
 108       bfd_set_error (bfd_error_bad_value);
 109       return NULL;
 110     }
 111
 112   if (elf32_wasm32_howto_table[i].type != r_type)
 113     return NULL;
 114
 115   return elf32_wasm32_howto_table + i;
 116 }
 117
 118 /* Translate the ELF-internal relocation RELA into CACHE_PTR.  */
 119
 120 static bfd_boolean
 121 elf32_wasm32_info_to_howto_rela (bfd *abfd,
 122                                 arelent *cache_ptr,
 123                                 Elf_Internal_Rela *dst)
 124 {
 125   unsigned int r_type = ELF32_R_TYPE (dst->r_info);
 126
 127   cache_ptr->howto = elf32_wasm32_rtype_to_howto (abfd, r_type);
 128   return cache_ptr->howto != NULL;
 129 }
 130
 131 #define ELF_ARCH                bfd_arch_wasm32
 132 #define ELF_TARGET_ID           EM_WEBASSEMBLY
 133 #define ELF_MACHINE_CODE        EM_WEBASSEMBLY
 134 /* FIXME we don't have paged executables, see:
 135    https://github.com/pipcet/binutils-gdb/issues/4  */
 136 #define ELF_MAXPAGESIZE         4096
 137
 138 #define TARGET_LITTLE_SYM       wasm32_elf32_vec
 139 #define TARGET_LITTLE_NAME      "elf32-wasm32"
 140
 141 #define elf_backend_can_gc_sections     1
 142 #define elf_backend_rela_normal         1
 143 /* For testing. */
 144 #define elf_backend_want_dynrelro       1
 145
 146 #define elf_info_to_howto               elf32_wasm32_info_to_howto_rela
 147 #define elf_info_to_howto_rel           NULL
 148
 149 #define bfd_elf32_bfd_reloc_type_lookup elf32_wasm32_reloc_type_lookup
 150 #define bfd_elf32_bfd_reloc_name_lookup elf32_wasm32_reloc_name_lookup
 151
 152 #define ELF_DYNAMIC_INTERPRETER  "/sbin/elf-dynamic-interpreter.so"
 153
 154 #define elf_backend_want_got_plt        1
 155 #define elf_backend_plt_readonly        1
 156 #define elf_backend_got_header_size     0
 157
 158 #include "elf32-target.h"