bfd/cpu-i386.c

   1 /* BFD support for the Intel 386 architecture.
   2    Copyright (C) 1992-2021 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, Boston,
  19    MA 02110-1301, USA.  */
  20
  21 #include "sysdep.h"
  22 #include "bfd.h"
  23 #include "libbfd.h"
  24 #include "libiberty.h"
  25
  26 extern void * bfd_arch_i386_short_nop_fill (bfd_size_type, bfd_boolean,
  27                                             bfd_boolean);
  28
  29 static const bfd_arch_info_type *
  30 bfd_i386_compatible (const bfd_arch_info_type *a,
  31                      const bfd_arch_info_type *b)
  32 {
  33   const bfd_arch_info_type *compat = bfd_default_compatible (a, b);
  34
  35   /* Don't allow mixing x64_32 with x86_64.  */
  36   if (compat
  37       && (a->mach & bfd_mach_x64_32) != (b->mach & bfd_mach_x64_32))
  38     compat = NULL;
  39
  40   return compat;
  41 }
  42
  43 /* Fill the buffer with zero or nop instruction if CODE is TRUE.  Use
  44    multi byte nop instructions if LONG_NOP is TRUE.  */
  45
  46 static void *
  47 bfd_arch_i386_fill (bfd_size_type count, bfd_boolean code,
  48                     bfd_boolean long_nop)
  49 {
  50   /* nop */
  51   static const char nop_1[] = { 0x90 };
  52   /* xchg %ax,%ax */
  53   static const char nop_2[] = { 0x66, 0x90 };
  54   /* nopl (%[re]ax) */
  55   static const char nop_3[] = { 0x0f, 0x1f, 0x00 };
  56   /* nopl 0(%[re]ax) */
  57   static const char nop_4[] = { 0x0f, 0x1f, 0x40, 0x00 };
  58   /* nopl 0(%[re]ax,%[re]ax,1) */
  59   static const char nop_5[] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
  60   /* nopw 0(%[re]ax,%[re]ax,1) */
  61   static const char nop_6[] = { 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00 };
  62   /* nopl 0L(%[re]ax) */
  63   static const char nop_7[] = { 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00 };
  64   /* nopl 0L(%[re]ax,%[re]ax,1) */
  65   static const char nop_8[] =
  66     { 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00};
  67   /* nopw 0L(%[re]ax,%[re]ax,1) */
  68   static const char nop_9[] =
  69     { 0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00 };
  70   /* nopw %cs:0L(%[re]ax,%[re]ax,1) */
  71   static const char nop_10[] =
  72     { 0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00 };
  73   static const char *const nops[] =
  74     { nop_1, nop_2, nop_3, nop_4, nop_5,
  75       nop_6, nop_7, nop_8, nop_9, nop_10 };
  76   bfd_size_type nop_size = long_nop ? ARRAY_SIZE (nops) : 2;
  77
  78   void *fill = bfd_malloc (count);
  79   if (fill == NULL)
  80     return fill;
  81
  82   if (code)
  83     {
  84       bfd_byte *p = fill;
  85       while (count >= nop_size)
  86         {
  87           memcpy (p, nops[nop_size - 1], nop_size);
  88           p += nop_size;
  89           count -= nop_size;
  90         }
  91       if (count != 0)
  92         memcpy (p, nops[count - 1], count);
  93     }
  94   else
  95     memset (fill, 0, count);
  96
  97   return fill;
  98 }
  99
 100 /* Fill the buffer with zero or short nop instruction if CODE is TRUE.  */
 101
 102 void *
 103 bfd_arch_i386_short_nop_fill (bfd_size_type count,
 104                               bfd_boolean is_bigendian ATTRIBUTE_UNUSED,
 105                               bfd_boolean code)
 106 {
 107   return bfd_arch_i386_fill (count, code, FALSE);
 108 }
 109
 110 /* Fill the buffer with zero or long nop instruction if CODE is TRUE.  */
 111
 112 static void *
 113 bfd_arch_i386_long_nop_fill (bfd_size_type count,
 114                              bfd_boolean is_bigendian ATTRIBUTE_UNUSED,
 115                              bfd_boolean code)
 116 {
 117   return bfd_arch_i386_fill (count, code, TRUE);
 118 }
 119
 120 #define N(BITS, MACH, NAME, PRINT, DEF, FILL, NEXT)     \
 121   { BITS, /* Bits in a word.  */                \
 122     BITS, /* Bits in an address.  */            \
 123     8,    /* Bits in a byte. */                 \
 124     bfd_arch_i386,                              \
 125     MACH, /* Machine number.  */                \
 126     NAME,                                       \
 127     PRINT,                                      \
 128     3,   /* Section alignment power.  */        \
 129     DEF, /* Default architecture version ?  */  \
 130     bfd_i386_compatible,                        \
 131     bfd_default_scan,                           \
 132     FILL,                                       \
 133     NEXT,                                       \
 134     0 /* Maximum instruction length.  */        \
 135   }
 136
 137
 138 static const bfd_arch_info_type bfd_x64_32_arch_intel_syntax =
 139   N (64, bfd_mach_x64_32_intel_syntax, "i386:intel", "i386:x64-32:intel",
 140      FALSE, bfd_arch_i386_long_nop_fill, NULL);
 141
 142 static const bfd_arch_info_type bfd_x86_64_arch_intel_syntax =
 143   N (64, bfd_mach_x86_64_intel_syntax, "i386:intel", "i386:x86-64:intel",
 144      FALSE, bfd_arch_i386_long_nop_fill, &bfd_x64_32_arch_intel_syntax);
 145
 146 static const bfd_arch_info_type bfd_i386_arch_intel_syntax =
 147   N (32, bfd_mach_i386_i386_intel_syntax, "i386:intel", "i386:intel",
 148      TRUE, bfd_arch_i386_short_nop_fill, &bfd_x86_64_arch_intel_syntax);
 149
 150
 151 static const bfd_arch_info_type i8086_arch =
 152   N (32, bfd_mach_i386_i8086, "i8086", "i8086",
 153      FALSE, bfd_arch_i386_short_nop_fill, &bfd_i386_arch_intel_syntax);
 154
 155 static const bfd_arch_info_type bfd_x64_32_arch =
 156   N (64, bfd_mach_x64_32, "i386", "i386:x64-32",
 157      FALSE, bfd_arch_i386_long_nop_fill, &i8086_arch);
 158
 159 static const bfd_arch_info_type bfd_x86_64_arch =
 160   N (64, bfd_mach_x86_64, "i386", "i386:x86-64",
 161      FALSE, bfd_arch_i386_long_nop_fill, &bfd_x64_32_arch);
 162
 163 const bfd_arch_info_type bfd_i386_arch =
 164   N (32, bfd_mach_i386_i386, "i386", "i386",
 165      TRUE, bfd_arch_i386_short_nop_fill, &bfd_x86_64_arch);