1 /* BFD support for the Intel 386 architecture.
2 Copyright (C) 1992-2023 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, bool,
27 bool);
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, bool code,
48 bool 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 bool is_bigendian ATTRIBUTE_UNUSED,
105 bool 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 bool is_bigendian ATTRIBUTE_UNUSED,
115 bool 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);