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3eb9473e | 1 | ;*****************************************************************************\r |
2 | ;*\r | |
3 | ;* Copyright (c) 2006 - 2007, Intel Corporation \r | |
4 | ;* All rights reserved. This program and the accompanying materials \r | |
5 | ;* are licensed and made available under the terms and conditions of the BSD License \r | |
6 | ;* which accompanies this distribution. The full text of the license may be found at \r | |
7 | ;* http://opensource.org/licenses/bsd-license.php \r | |
8 | ;* \r | |
9 | ;* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r | |
10 | ;* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r | |
11 | ;* \r | |
12 | ;* Module Name:\r | |
13 | ;*\r | |
14 | ;* Thunk.asm\r | |
15 | ;* \r | |
16 | ;* Abstract:\r | |
17 | ;* \r | |
18 | ;* Real mode thunk\r | |
19 | ;* \r | |
20 | ;*****************************************************************************\r | |
21 | \r | |
22 | .686p\r | |
23 | \r | |
24 | EXTERNDEF C mCode16Size:DWORD\r | |
25 | \r | |
26 | CONST SEGMENT FLAT "DATA" READONLY\r | |
27 | \r | |
28 | mCode16Size DD _TEXT16SIZE\r | |
29 | \r | |
30 | CONST ENDS\r | |
31 | \r | |
32 | _DATA SEGMENT FLAT "DATA"\r | |
33 | \r | |
34 | NullSegSel DQ 0\r | |
35 | _16BitCsSel LABEL QWORD\r | |
36 | DW -1\r | |
37 | DW 0\r | |
38 | DB 0\r | |
39 | DB 9bh\r | |
40 | DB 8fh ; 16-bit segment\r | |
41 | DB 0\r | |
42 | _16BitSsSel LABEL QWORD\r | |
43 | DW -1\r | |
44 | DW 0\r | |
45 | DB 0\r | |
46 | DB 93h\r | |
47 | DB 8fh ; 16-bit segment\r | |
48 | DB 0\r | |
49 | \r | |
50 | _16Gdtr LABEL FWORD\r | |
51 | DW $ - offset NullSegSel - 1\r | |
52 | DD offset NullSegSel\r | |
53 | \r | |
54 | _DATA ENDS\r | |
55 | \r | |
56 | _TEXT SEGMENT FLAT "CODE" PARA\r | |
57 | \r | |
58 | IA32_REGS STRUC 4t\r | |
59 | _EDI DD ?\r | |
60 | _ESI DD ?\r | |
61 | _EBP DD ?\r | |
62 | _ESP DD ?\r | |
63 | _EBX DD ?\r | |
64 | _EDX DD ?\r | |
65 | _ECX DD ?\r | |
66 | _EAX DD ?\r | |
67 | _DS DW ?\r | |
68 | _ES DW ?\r | |
69 | _FS DW ?\r | |
70 | _GS DW ?\r | |
71 | _EFLAGS DD ?\r | |
72 | _EIP DD ?\r | |
73 | _CS DW ?\r | |
74 | _SS DW ?\r | |
75 | IA32_REGS ENDS\r | |
76 | \r | |
77 | _STK16 STRUC 1t\r | |
78 | RetEip DD ?\r | |
79 | RetCs DW ?\r | |
80 | ThunkFlags DW ?\r | |
81 | SavedEsp DD ?\r | |
82 | SavedSs DW ?\r | |
83 | SavedGdtr FWORD ?\r | |
84 | SavedCr0 DD ?\r | |
85 | SavedCr4 DD ?\r | |
86 | _STK16 ENDS\r | |
87 | \r | |
88 | ASSUME ds:_DATA\r | |
89 | \r | |
90 | __Thunk16 PROC USES ebp ebx esi edi ds es fs gs\r | |
91 | ASSUME esi:PTR IA32_REGS\r | |
92 | mov esi, [esp + 36]\r | |
93 | movzx edx, [esi]._SS\r | |
94 | mov edi, [esi]._ESP\r | |
95 | add edi, - sizeof (_STK16) - sizeof (IA32_REGS)\r | |
96 | push edi ; save stack offset\r | |
97 | imul eax, edx, 16 ; eax <- edx*16\r | |
98 | add edi, eax ; edi <- linear address of 16-bit stack\r | |
99 | push sizeof (IA32_REGS) / 4\r | |
100 | pop ecx\r | |
101 | rep movsd ; copy context to 16-bit stack\r | |
102 | pop ebx ; ebx <- 16-bit stack offset\r | |
103 | mov eax, offset @F ; return offset\r | |
104 | stosd\r | |
105 | mov eax, cs ; return segment\r | |
106 | stosw\r | |
107 | mov eax, [esp + 40] ; THUNK flags\r | |
108 | stosw\r | |
109 | mov eax, esp\r | |
110 | stosd ; save esp\r | |
111 | mov eax, ss ; save ss\r | |
112 | stosw\r | |
113 | sgdt fword ptr [edi] ; save GDTR\r | |
114 | sidt fword ptr [esp + 36] ; save IDTR\r | |
115 | mov esi, cr0\r | |
116 | mov [edi + 6], esi ; save CR0\r | |
117 | and esi, NOT 80000001h ; esi <- CR0 to set\r | |
118 | mov eax, cr4\r | |
119 | mov [edi + 10], eax ; save CR4\r | |
120 | and al, NOT 30h ; clear PAE & PSE\r | |
121 | mov edi, edx ; edi <- 16-bit stack segment\r | |
122 | mov edx, [esp + 44]\r | |
123 | shl edx, 16\r | |
124 | push edx\r | |
125 | pop edx\r | |
126 | mov dx, _16BitSsSel - NullSegSel\r | |
127 | lgdt _16Gdtr ; load 16-bit GDTR\r | |
128 | DB 0eah\r | |
129 | DD offset @16Bit\r | |
130 | DW _16BitCsSel - NullSegSel ; jmp far 8:@16Bit\r | |
131 | @16Bit:\r | |
132 | mov ss, dx\r | |
133 | mov cr0, esi ; disable protected mode\r | |
134 | mov cr4, eax ; disable PAE & PSE\r | |
135 | db 67h, 0FFh, 06Ch, 024h, 0FCh ; jmp dword ptr [esp-4]\r | |
136 | @@:\r | |
137 | mov eax, ss\r | |
138 | shl eax, 4\r | |
139 | add eax, esp ; eax <- address of 16-bit stack\r | |
140 | lss esp, fword ptr (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedEsp\r | |
141 | lidt fword ptr [esp + 36] ; restore IDTR\r | |
142 | ret\r | |
143 | __Thunk16 ENDP\r | |
144 | \r | |
145 | _TEXT ENDS\r | |
146 | \r | |
147 | _TEXT16 SEGMENT USE16 "CODE" PARA\r | |
148 | \r | |
149 | _Code16Addr PROC C\r | |
150 | _Code16Addr ENDP\r | |
151 | \r | |
152 | RealMode PROC\r | |
153 | mov ss, di ; set up stack\r | |
154 | mov esp, ebx\r | |
155 | lidt fword ptr cs:[_16Idtr - _Code16Addr]\r | |
156 | popad\r | |
157 | pop ds\r | |
158 | pop es\r | |
159 | pop fs\r | |
160 | pop gs\r | |
161 | add sp, 4 ; skip EFlags\r | |
162 | test (_STK16 ptr [esp + 8]).ThunkFlags, 1\r | |
163 | jz @F\r | |
164 | pushf\r | |
165 | @@:\r | |
166 | push cs\r | |
167 | ; push @FarCallRet - _Code16Addr\r | |
168 | DB 68h ; push /iw\r | |
169 | DW @FarCallRet - _Code16Addr\r | |
170 | jz @F\r | |
171 | jmp fword ptr [esp + 6]\r | |
172 | @@:\r | |
173 | jmp fword ptr [esp + 4]\r | |
174 | @FarCallRet:\r | |
175 | pushfd\r | |
176 | push gs\r | |
177 | push fs\r | |
178 | push es\r | |
179 | push ds\r | |
180 | pushad\r | |
181 | cli\r | |
182 | DB 66h\r | |
183 | lgdt (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedGdtr\r | |
184 | mov eax, (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedCr4\r | |
185 | mov cr4, eax\r | |
186 | mov eax, (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedCr0\r | |
187 | mov cr0, eax ; restore CR0\r | |
188 | jmp fword ptr (_STK16 ptr [esp + sizeof (IA32_REGS)]).RetEip\r | |
189 | RealMode ENDP\r | |
190 | \r | |
191 | _16Idtr FWORD (1 SHL 10) - 1\r | |
192 | \r | |
193 | _TEXT16END:\r | |
194 | \r | |
195 | _TEXT16SIZE = _TEXT16END - _Code16Addr\r | |
196 | \r | |
197 | _TEXT16 ENDS\r | |
198 | \r | |
199 | END\r |