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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 | |
44cf7a02 | 14 | # Thunk16.S\r |
878ddf1f | 15 | #\r |
16 | # Abstract:\r | |
17 | #\r | |
18 | # Real mode thunk\r | |
19 | #\r | |
20 | #------------------------------------------------------------------------------\r | |
21 | \r | |
b7089db1 | 22 | .globl _m16Start, _m16Size, _mThunk16Attr, _m16Gdt, _m16GdtrBase, _mTransition\r |
23 | .globl _InternalAsmThunk16\r | |
44cf7a02 | 24 | \r |
3f566587 | 25 | _m16Start:\r |
44cf7a02 | 26 | \r |
27 | SavedGdt: .space 6\r | |
28 | \r | |
29 | _BackFromUserCode:\r | |
30 | push %ss\r | |
31 | push %cs\r | |
32 | .byte 0x66\r | |
b7089db1 | 33 | call L_Base1 # push eip\r |
34 | L_Base1:\r | |
44cf7a02 | 35 | pushfw # pushfd actually\r |
36 | cli # disable interrupts\r | |
37 | push %gs\r | |
38 | push %fs\r | |
39 | push %es\r | |
40 | push %ds\r | |
41 | pushaw # pushad actually\r | |
b7089db1 | 42 | .byte 0x66, 0xba # mov edx, imm32\r |
44cf7a02 | 43 | _ThunkAttr: .space 4\r |
44 | testb $THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15, %dl\r | |
b7089db1 | 45 | jz 1f\r |
44cf7a02 | 46 | movl $0x15cd2401, %eax # mov ax, 2401h & int 15h\r |
47 | cli # disable interrupts\r | |
b7089db1 | 48 | jnc 2f\r |
49 | 1:\r | |
44cf7a02 | 50 | testb $THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL, %dl\r |
b7089db1 | 51 | jz 2f\r |
44cf7a02 | 52 | inb $0x92, %al\r |
53 | orb $2, %al\r | |
54 | outb %al, $0x92 # deactivate A20M#\r | |
b7089db1 | 55 | 2:\r |
44cf7a02 | 56 | movl %ss, %eax\r |
57 | .byte 0x67, 0x66, 0x8d, 0x6c, 0x24, 0x34, 0x66\r | |
3f566587 | 58 | mov %ebp, 0xffffffd8(%esi)\r |
59 | mov 0xfffffff8(%esi), %ebx\r | |
44cf7a02 | 60 | shlw $4, %ax # shl eax, 4\r |
61 | addw %ax, %bp # add ebp, eax\r | |
3f566587 | 62 | .byte 0x66, 0xb8 # mov eax, imm32\r |
44cf7a02 | 63 | SavedCr4: .space 4\r |
64 | movl %eax, %cr4\r | |
3f566587 | 65 | lgdtw %cs:0xfffffff2(%edi)\r |
66 | .byte 0x66, 0xb8 # mov eax, imm32\r | |
44cf7a02 | 67 | SavedCr0: .space 4\r |
68 | movl %eax, %cr0\r | |
69 | .byte 0xb8 # mov ax, imm16\r | |
70 | SavedSs: .space 2\r | |
71 | movl %eax, %ss\r | |
3f566587 | 72 | .byte 0x66, 0xbc # mov esp, imm32\r |
44cf7a02 | 73 | SavedEsp: .space 4\r |
74 | .byte 0x66\r | |
75 | lret # return to protected mode\r | |
76 | \r | |
77 | _EntryPoint: .long _ToUserCode - _m16Start\r | |
78 | .word 0x8\r | |
79 | _16Idtr: .word 0x3ff\r | |
80 | .long 0\r | |
81 | _16Gdtr: .word GdtEnd - _NullSegDesc - 1\r | |
82 | _16GdtrBase: .long _NullSegDesc\r | |
83 | \r | |
84 | _ToUserCode:\r | |
85 | movl %ss, %edx\r | |
86 | movl %ecx, %ss # set new segment selectors\r | |
87 | movl %ecx, %ds\r | |
88 | movl %ecx, %es\r | |
89 | movl %ecx, %fs\r | |
90 | movl %ecx, %gs\r | |
91 | movl %eax, %cr0\r | |
92 | movl %ebp, %cr4 # real mode starts at next instruction\r | |
93 | movl %esi, %ss # set up 16-bit stack segment\r | |
94 | xchgw %bx, %sp # set up 16-bit stack pointer\r | |
95 | .byte 0x66\r | |
b7089db1 | 96 | call L_Base # push eip\r |
97 | L_Base:\r | |
98 | popw %bp # ebp <- offset L_Base\r | |
44cf7a02 | 99 | addr16 pushl 36(%si)\r |
100 | .byte 0x36\r | |
3f566587 | 101 | lea 0xc(%esi), %eax\r |
102 | push %eax\r | |
44cf7a02 | 103 | lret\r |
104 | \r | |
b7089db1 | 105 | L_RealMode:\r |
3f566587 | 106 | mov %edx, %cs:0xffffffc5(%esi)\r |
107 | mov %bx, %cs:0xffffffcb(%esi)\r | |
44cf7a02 | 108 | lidtw %cs:0xffffffd7(%esi)\r |
109 | popaw # popad actually\r | |
3f566587 | 110 | pop %ds\r |
111 | pop %es\r | |
112 | pop %fs\r | |
113 | pop %gs\r | |
44cf7a02 | 114 | popfw # popfd\r |
115 | lretw # transfer control to user code\r | |
116 | \r | |
117 | _NullSegDesc: .quad 0\r | |
118 | _16CsDesc:\r | |
119 | .word -1\r | |
120 | .word 0\r | |
121 | .byte 0\r | |
122 | .byte 0x9b\r | |
123 | .byte 0x8f # 16-bit segment, 4GB limit\r | |
124 | .byte 0\r | |
125 | _16DsDesc:\r | |
126 | .word -1\r | |
127 | .word 0\r | |
128 | .byte 0\r | |
129 | .byte 0x93\r | |
130 | .byte 0x8f # 16-bit segment, 4GB limit\r | |
131 | .byte 0\r | |
132 | GdtEnd:\r | |
133 | \r | |
134 | #\r | |
135 | # @param RegSet Pointer to a IA32_DWORD_REGS structure\r | |
136 | # @param Transition Pointer to the transition code\r | |
137 | # @return The address of the 16-bit stack after returning from user code\r | |
138 | #\r | |
bd0cd44b | 139 | _InternalAsmThunk16:\r |
44cf7a02 | 140 | push %ebp\r |
141 | push %ebx\r | |
142 | push %esi\r | |
143 | push %edi\r | |
144 | push %ds\r | |
145 | push %es\r | |
146 | push %fs\r | |
147 | push %gs\r | |
148 | movl 36(%esp), %esi # esi <- RegSet\r | |
3f566587 | 149 | movzwl 0x32(%esi), %edx\r |
150 | mov 0xc(%esi), %edi\r | |
151 | add $0xffffffc8, %edi\r | |
44cf7a02 | 152 | movl %edi, %ebx # ebx <- stack offset\r |
3f566587 | 153 | imul $0x10, %edx, %eax\r |
44cf7a02 | 154 | push $0xd\r |
155 | addl %eax, %edi # edi <- linear address of 16-bit stack\r | |
3f566587 | 156 | pop %ecx\r |
44cf7a02 | 157 | rep\r |
158 | movsl # copy RegSet\r | |
159 | movl 40(%esp), %eax # eax <- address of transition code\r | |
160 | movl %edx, %esi # esi <- 16-bit stack segment\r | |
3f566587 | 161 | lea 0x5e(%eax), %edx\r |
44cf7a02 | 162 | movl %eax, %ecx\r |
163 | andl $0xf, %ecx\r | |
164 | shll $12, %eax\r | |
3f566587 | 165 | lea 0x6(%ecx), %ecx\r |
44cf7a02 | 166 | movw %cx, %ax\r |
167 | stosl # [edi] <- return address of user code\r | |
3f566587 | 168 | sgdtl 0xffffffa2(%edx)\r |
44cf7a02 | 169 | sidtl 0x24(%esp)\r |
170 | movl %cr0, %eax\r | |
171 | movl %eax, (%edx) # save CR0 in SavedCr0\r | |
172 | andl $0x7ffffffe, %eax # clear PE, PG bits\r | |
173 | movl %cr4, %ebp\r | |
3f566587 | 174 | mov %ebp, 0xfffffff1(%edx)\r |
44cf7a02 | 175 | andl $0x300, %ebp # clear all but PCE and OSFXSR bits\r |
176 | pushl $0x10\r | |
3f566587 | 177 | pop %ecx # ecx <- selector for data segments\r |
44cf7a02 | 178 | lgdtl 0x20(%edx)\r |
179 | pushfl\r | |
180 | lcall *0x14(%edx)\r | |
181 | popfl\r | |
182 | lidtl 0x24(%esp)\r | |
3f566587 | 183 | lea 0xffffffcc(%ebp), %eax\r |
44cf7a02 | 184 | pop %gs\r |
185 | pop %fs\r | |
186 | pop %es\r | |
187 | pop %ds\r | |
188 | pop %edi\r | |
189 | pop %esi\r | |
190 | pop %ebx\r | |
191 | pop %ebp\r | |
192 | ret\r | |
193 | \r | |
3f566587 | 194 | .const:\r |
44cf7a02 | 195 | \r |
196 | _m16Size: .word _InternalAsmThunk16 - _m16Start\r | |
197 | _mThunk16Attr: .word _ThunkAttr - _m16Start\r | |
198 | _m16Gdt: .word _NullSegDesc - _m16Start\r | |
199 | _m16GdtrBase: .word _16GdtrBase - _m16Start\r | |
200 | _mTransition: .word _EntryPoint - _m16Start\r |