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878ddf1f | 1 | ;------------------------------------------------------------------------------\r |
2 | ;\r | |
3 | ; Copyright (c) 2006, 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 | |
97d92bda | 22 | EXTERNDEF m16Start:BYTE\r |
23 | EXTERNDEF m16Size:WORD\r | |
24 | EXTERNDEF mThunk16Attr:WORD\r | |
25 | EXTERNDEF m16Gdt:WORD\r | |
26 | EXTERNDEF m16GdtrBase:WORD\r | |
27 | EXTERNDEF mTransition:WORD\r | |
878ddf1f | 28 | \r |
878ddf1f | 29 | IA32_REGS STRUC 4t\r |
30 | _EDI DD ?\r | |
31 | _ESI DD ?\r | |
32 | _EBP DD ?\r | |
33 | _ESP DD ?\r | |
34 | _EBX DD ?\r | |
35 | _EDX DD ?\r | |
36 | _ECX DD ?\r | |
37 | _EAX DD ?\r | |
38 | _DS DW ?\r | |
39 | _ES DW ?\r | |
40 | _FS DW ?\r | |
41 | _GS DW ?\r | |
97d92bda | 42 | _EFLAGS DQ ?\r |
878ddf1f | 43 | _EIP DD ?\r |
44 | _CS DW ?\r | |
45 | _SS DW ?\r | |
46 | IA32_REGS ENDS\r | |
47 | \r | |
97d92bda | 48 | .const\r |
49 | \r | |
bbe4ba81 | 50 | m16Size DW InternalAsmThunk16 - m16Start\r |
51 | mThunk16Attr DW _ThunkAttr - m16Start\r | |
f23d790a | 52 | m16Gdt DW _NullSeg - m16Start\r |
bbe4ba81 | 53 | m16GdtrBase DW _16GdtrBase - m16Start\r |
54 | mTransition DW _EntryPoint - m16Start\r | |
97d92bda | 55 | \r |
56 | .code\r | |
57 | \r | |
58 | m16Start LABEL BYTE\r | |
59 | \r | |
bbe4ba81 | 60 | SavedGdt LABEL FWORD\r |
61 | DW ?\r | |
62 | DQ ?\r | |
97d92bda | 63 | \r |
3f566587 | 64 | ;------------------------------------------------------------------------------\r |
65 | ; _BackFromUserCode() takes control in real mode after 'retf' has been executed\r | |
66 | ; by user code. It will be shadowed to somewhere in memory below 1MB.\r | |
67 | ;------------------------------------------------------------------------------\r | |
97d92bda | 68 | _BackFromUserCode PROC\r |
a9a812a0 | 69 | ;\r |
70 | ; The order of saved registers on the stack matches the order they appears\r | |
71 | ; in IA32_REGS structure. This facilitates wrapper function to extract them\r | |
72 | ; into that structure.\r | |
73 | ;\r | |
74 | ; Some instructions for manipulation of segment registers have to be written\r | |
75 | ; in opcode since 64-bit MASM prevents accesses to those registers.\r | |
76 | ;\r | |
97d92bda | 77 | DB 16h ; push ss\r |
78 | DB 0eh ; push cs\r | |
878ddf1f | 79 | DB 66h\r |
97d92bda | 80 | call @Base ; push eip\r |
81 | @Base:\r | |
878ddf1f | 82 | DB 66h\r |
97d92bda | 83 | push 0 ; reserved high order 32 bits of EFlags\r |
878ddf1f | 84 | pushf ; pushfd actually\r |
97d92bda | 85 | cli ; disable interrupts\r |
878ddf1f | 86 | push gs\r |
87 | push fs\r | |
88 | DB 6 ; push es\r | |
89 | DB 1eh ; push ds\r | |
90 | DB 66h, 60h ; pushad\r | |
97d92bda | 91 | DB 66h, 0bah ; mov edx, imm32\r |
92 | _ThunkAttr DD ?\r | |
93 | test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15\r | |
94 | jz @1\r | |
95 | mov eax, 15cd2401h ; mov ax, 2401h & int 15h\r | |
96 | cli ; disable interrupts\r | |
97 | jnc @2\r | |
98 | @1:\r | |
99 | test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL\r | |
100 | jz @2\r | |
101 | in al, 92h\r | |
102 | or al, 2\r | |
103 | out 92h, al ; deactivate A20M#\r | |
104 | @2:\r | |
105 | mov eax, ss\r | |
106 | lea bp, [esp + sizeof (IA32_REGS)]\r | |
733f4094 | 107 | ;\r |
108 | ; rsi in the following 2 instructions is indeed bp in 16-bit code\r | |
109 | ;\r | |
97d92bda | 110 | mov word ptr (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._ESP, bp\r |
733f4094 | 111 | DB 66h\r |
97d92bda | 112 | mov ebx, (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._EIP\r |
113 | shl ax, 4 ; shl eax, 4\r | |
114 | add bp, ax ; add ebp, eax\r | |
38b5365e | 115 | mov ax, cs\r |
116 | shl ax, 4\r | |
117 | lea ax, [eax + ebx + (@64BitCode - @Base)]\r | |
733f4094 | 118 | DB 66h, 2eh, 89h, 87h ; mov cs:[bx + (@64Eip - @Base)], eax\r |
119 | DW @64Eip - @Base\r | |
97d92bda | 120 | DB 66h, 0b8h ; mov eax, imm32\r |
121 | SavedCr4 DD ?\r | |
122 | mov cr4, rax\r | |
733f4094 | 123 | ;\r |
124 | ; rdi in the instruction below is indeed bx in 16-bit code\r | |
125 | ;\r | |
a9a812a0 | 126 | DB 66h, 2eh ; 2eh is "cs:" segment override\r |
bbe4ba81 | 127 | lgdt fword ptr [rdi + (SavedGdt - @Base)]\r |
878ddf1f | 128 | DB 66h\r |
129 | mov ecx, 0c0000080h\r | |
130 | rdmsr\r | |
97d92bda | 131 | or ah, 1\r |
878ddf1f | 132 | wrmsr\r |
97d92bda | 133 | DB 66h, 0b8h ; mov eax, imm32\r |
134 | SavedCr0 DD ?\r | |
135 | mov cr0, rax\r | |
38b5365e | 136 | DB 66h, 0eah ; jmp far cs:@64Bit\r |
137 | @64Eip DD ?\r | |
138 | SavedCs DW ?\r | |
139 | @64BitCode:\r | |
a9a812a0 | 140 | mov rsp, r8 ; restore stack\r |
141 | ret\r | |
97d92bda | 142 | _BackFromUserCode ENDP\r |
143 | \r | |
bbe4ba81 | 144 | _EntryPoint DD _ToUserCode - m16Start\r |
f23d790a | 145 | DW CODE16\r |
bbe4ba81 | 146 | _16Gdtr LABEL FWORD\r |
f23d790a | 147 | DW GDT_SIZE - 1\r |
148 | _16GdtrBase DQ _NullSeg\r | |
bbe4ba81 | 149 | _16Idtr FWORD (1 SHL 10) - 1\r |
97d92bda | 150 | \r |
3f566587 | 151 | ;------------------------------------------------------------------------------\r |
152 | ; _ToUserCode() takes control in real mode before passing control to user code.\r | |
153 | ; It will be shadowed to somewhere in memory below 1MB.\r | |
154 | ;------------------------------------------------------------------------------\r | |
97d92bda | 155 | _ToUserCode PROC\r |
97d92bda | 156 | mov ss, edx ; set new segment selectors\r |
157 | mov ds, edx\r | |
158 | mov es, edx\r | |
159 | mov fs, edx\r | |
160 | mov gs, edx\r | |
878ddf1f | 161 | DB 66h\r |
97d92bda | 162 | mov ecx, 0c0000080h\r |
163 | mov cr0, rax ; real mode starts at next instruction\r | |
164 | rdmsr\r | |
165 | and ah, NOT 1\r | |
166 | wrmsr\r | |
167 | mov cr4, rbp\r | |
168 | mov ss, esi ; set up 16-bit stack segment\r | |
38b5365e | 169 | mov sp, bx ; set up 16-bit stack pointer\r |
a9a812a0 | 170 | DB 66h ; make the following call 32-bit\r |
97d92bda | 171 | call @Base ; push eip\r |
172 | @Base:\r | |
bbe4ba81 | 173 | pop bp ; ebp <- address of @Base\r |
18c319ae | 174 | push [esp + sizeof (IA32_REGS) + 2]\r |
a9a812a0 | 175 | lea eax, [rsi + (@RealMode - @Base)] ; rsi is "bp" in 16-bit code\r |
18c319ae | 176 | push rax\r |
a9a812a0 | 177 | retf ; execution begins at next instruction\r |
18c319ae | 178 | @RealMode:\r |
97d92bda | 179 | DB 66h, 2eh ; CS and operand size override\r |
bbe4ba81 | 180 | lidt fword ptr [rsi + (_16Idtr - @Base)]\r |
97d92bda | 181 | DB 66h, 61h ; popad\r |
182 | DB 1fh ; pop ds\r | |
183 | DB 07h ; pop es\r | |
184 | pop fs\r | |
185 | pop gs\r | |
186 | popf ; popfd\r | |
187 | lea sp, [esp + 4] ; skip high order 32 bits of EFlags\r | |
a9a812a0 | 188 | DB 66h ; make the following retf 32-bit\r |
97d92bda | 189 | retf ; transfer control to user code\r |
190 | _ToUserCode ENDP\r | |
191 | \r | |
f23d790a | 192 | CODE16 = _16Code - $\r |
193 | DATA16 = _16Data - $\r | |
194 | DATA32 = _32Data - $\r | |
195 | \r | |
196 | _NullSeg DQ 0\r | |
197 | _16Code LABEL QWORD\r | |
198 | DW -1\r | |
199 | DW 0\r | |
200 | DB 0\r | |
201 | DB 9bh\r | |
202 | DB 8fh ; 16-bit segment, 4GB limit\r | |
203 | DB 0\r | |
204 | _16Data LABEL QWORD\r | |
205 | DW -1\r | |
206 | DW 0\r | |
207 | DB 0\r | |
208 | DB 93h\r | |
209 | DB 8fh ; 16-bit segment, 4GB limit\r | |
210 | DB 0\r | |
211 | _32Data LABEL QWORD\r | |
212 | DW -1\r | |
213 | DW 0\r | |
214 | DB 0\r | |
215 | DB 93h\r | |
216 | DB 0cfh ; 16-bit segment, 4GB limit\r | |
217 | DB 0\r | |
218 | \r | |
219 | GDT_SIZE = $ - _NullSeg\r | |
97d92bda | 220 | \r |
3f566587 | 221 | ;------------------------------------------------------------------------------\r |
222 | ; IA32_REGISTER_SET *\r | |
223 | ; EFIAPI\r | |
224 | ; InternalAsmThunk16 (\r | |
225 | ; IN IA32_REGISTER_SET *RegisterSet,\r | |
226 | ; IN OUT VOID *Transition\r | |
227 | ; );\r | |
228 | ;------------------------------------------------------------------------------\r | |
97d92bda | 229 | InternalAsmThunk16 PROC USES rbp rbx rsi rdi\r |
a9a812a0 | 230 | mov r10d, ds ; r9 ~ r11 are not accessible in 16-bit\r |
231 | mov r11d, es ; so use them for saving seg registers\r | |
f23d790a | 232 | mov r9d, ss\r |
97d92bda | 233 | push fs\r |
234 | push gs\r | |
235 | mov rsi, rcx\r | |
236 | movzx r8d, (IA32_REGS ptr [rsi])._SS\r | |
237 | mov edi, (IA32_REGS ptr [rsi])._ESP\r | |
238 | lea rdi, [edi - (sizeof (IA32_REGS) + 4)]\r | |
239 | imul eax, r8d, 16 ; eax <- r8d(stack segment) * 16\r | |
bbe4ba81 | 240 | mov ebx, edi ; ebx <- stack for 16-bit code\r |
97d92bda | 241 | push sizeof (IA32_REGS) / 4\r |
242 | add edi, eax ; edi <- linear address of 16-bit stack\r | |
243 | pop rcx\r | |
244 | rep movsd ; copy RegSet\r | |
bbe4ba81 | 245 | lea ecx, [rdx + (SavedCr4 - m16Start)]\r |
97d92bda | 246 | mov eax, edx ; eax <- transition code address\r |
247 | and edx, 0fh\r | |
a9a812a0 | 248 | shl eax, 12 ; segment address in high order 16 bits\r |
249 | lea ax, [rdx + (_BackFromUserCode - m16Start)] ; offset address\r | |
97d92bda | 250 | stosd ; [edi] <- return address of user code\r |
bbe4ba81 | 251 | sgdt fword ptr [rcx + (SavedGdt - SavedCr4)]\r |
97d92bda | 252 | sidt fword ptr [rsp + 38h] ; save IDT stack in argument space\r |
253 | mov rax, cr0\r | |
bbe4ba81 | 254 | mov [rcx + (SavedCr0 - SavedCr4)], eax\r |
97d92bda | 255 | and eax, 7ffffffeh ; clear PE, PG bits\r |
256 | mov rbp, cr4\r | |
257 | mov [rcx], ebp ; save CR4 in SavedCr4\r | |
258 | and ebp, 300h ; clear all but PCE and OSFXSR bits\r | |
259 | mov esi, r8d ; esi <- 16-bit stack segment\r | |
f23d790a | 260 | DB 6ah, DATA32 ; push DATA32\r |
261 | pop rdx ; rdx <- 32-bit data segment selector\r | |
bbe4ba81 | 262 | lgdt fword ptr [rcx + (_16Gdtr - SavedCr4)]\r |
f23d790a | 263 | mov ss, edx\r |
18c319ae | 264 | pushfq\r |
f23d790a | 265 | lea edx, [rdx + DATA16 - DATA32]\r |
38b5365e | 266 | lea r8, @RetFromRealMode\r |
a9a812a0 | 267 | push r8\r |
38b5365e | 268 | mov r8d, cs\r |
269 | mov [rcx + (SavedCs - SavedCr4)], r8w\r | |
270 | mov r8, rsp\r | |
271 | jmp fword ptr [rcx + (_EntryPoint - SavedCr4)]\r | |
272 | @RetFromRealMode:\r | |
18c319ae | 273 | popfq\r |
97d92bda | 274 | lidt fword ptr [rsp + 38h] ; restore protected mode IDTR\r |
275 | lea eax, [rbp - sizeof (IA32_REGS)]\r | |
878ddf1f | 276 | pop gs\r |
277 | pop fs\r | |
f23d790a | 278 | mov ss, r9d\r |
97d92bda | 279 | mov es, r11d\r |
280 | mov ds, r10d\r | |
878ddf1f | 281 | ret\r |
282 | InternalAsmThunk16 ENDP\r | |
283 | \r | |
284 | END\r |