Fix CYG GCC build fail on retf.
[mirror_edk2.git] / EdkCompatibilityPkg / Compatibility / BootScriptSaveOnS3SaveStateThunk / X64 / AsmDispatchExecute.S
1 #
2 # Copyright (c) 2010, Intel Corporation. All rights reserved.<BR>
3 # This program and the accompanying materials
4 # are licensed and made available under the terms and conditions of the BSD License
5 # which accompanies this distribution. The full text of the license may be found at
6 # http://opensource.org/licenses/bsd-license.php
7 #
8 # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
9 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
10 #
11 #
12 # Module Name:
13 #
14 # AsmDispatchExecute.asm
15 #
16 # Abstract:
17 #
18 # This is the assembly code to transition from long mode to compatibility mode to execute 32-bit code and then
19 # transit back to long mode.
20 #
21 #-------------------------------------------------------------------------------
22
23 #----------------------------------------------------------------------------
24 # Procedure: AsmExecute32BitCode
25 #
26 # Input: None
27 #
28 # Output: None
29 #
30 # Prototype: EFI_STATUS
31 # AsmExecute32BitCode (
32 # IN UINT64 Function,
33 # IN UINT64 Param1,
34 # IN UINT64 Param2,
35 # IN IA32_DESCRIPTOR *InternalGdtr
36 # );
37 #
38 #
39 # Description: A thunk function to execute 32-bit code in long mode.
40 #
41 #----------------------------------------------------------------------------
42
43 ASM_GLOBAL ASM_PFX(AsmExecute32BitCode)
44 ASM_PFX(AsmExecute32BitCode):
45 #
46 # save orignal GDTR and CS
47 #
48 movq %ds, %rax
49 push %rax
50 movq %cs, %rax
51 push %rax
52 subq $0x10, %rsp
53 sgdt (%rsp)
54 #
55 # load internal GDT
56 #
57 lgdt (%r9)
58 #
59 # Save general purpose register and rflag register
60 #
61 pushfq
62 push %rdi
63 push %rsi
64 push %rbp
65 push %rbx
66
67 #
68 # save CR3
69 #
70 movq %cr3, %rax
71 movq %rax, %rbp
72
73 #
74 # Prepare the CS and return address for the transition from 32-bit to 64-bit mode
75 #
76 movq $0x10, %rax # load long mode selector
77 shl $32, %rax
78 lea ReloadCS(%rip), %r9 #Assume the ReloadCS is under 4G
79 orq %r9, %rax
80 push %rax
81 #
82 # Save parameters for 32-bit function call
83 #
84 movq %r8, %rax
85 shl $32, %rax
86 orq %rdx, %rax
87 push %rax
88 #
89 # save the 32-bit function entry and the return address into stack which will be
90 # retrieve in compatibility mode.
91 #
92 lea ReturnBack(%rip), %rax #Assume the ReloadCS is under 4G
93 shl $32, %rax
94 orq %rcx, %rax
95 push %rax
96
97 #
98 # let rax save DS
99 #
100 movq $0x18, %rax
101
102 #
103 # Change to Compatible Segment
104 #
105 movq $8, %rcx # load compatible mode selector
106 shl $32, %rcx
107 lea Compatible(%rip), %rdx # assume address < 4G
108 orq %rdx, %rcx
109 push %rcx
110 .byte 0xcb # retf
111
112 Compatible:
113 # reload DS/ES/SS to make sure they are correct referred to current GDT
114 movw %ax, %ds
115 movw %ax, %es
116 movw %ax, %ss
117
118 #
119 # Disable paging
120 #
121 movq %cr0, %rcx
122 btc $31, %ecx
123 movq %rcx, %cr0
124 #
125 # Clear EFER.LME
126 #
127 movl $0xC0000080, %ecx
128 rdmsr
129 btc $8, %eax
130 wrmsr
131
132 # Now we are in protected mode
133 #
134 # Call 32-bit function. Assume the function entry address and parameter value is less than 4G
135 #
136 pop %rax # Here is the function entry
137 #
138 # Now the parameter is at the bottom of the stack, then call in to IA32 function.
139 #
140 jmp *%rax
141 ReturnBack:
142 pop %rcx # drop param1
143 pop %rcx # drop param2
144
145 #
146 # restore CR4
147 #
148 movq %cr4, %rax
149 bts $5, %eax
150 movq %rax, %cr4
151
152 #
153 # restore CR3
154 #
155 movl %ebp, %eax
156 movq %rax, %cr3
157
158 #
159 # Set EFER.LME to re-enable ia32-e
160 #
161 movl $0xC0000080, %ecx
162 rdmsr
163 bts $8, %eax
164 wrmsr
165 #
166 # Enable paging
167 #
168 movq %cr0, %rax
169 bts $31, %eax
170 mov %rax, %cr0
171 # Now we are in compatible mode
172
173 #
174 # Reload cs register
175 #
176 .byte 0xcb # retf
177 ReloadCS:
178 #
179 # Now we're in Long Mode
180 #
181 #
182 # Restore C register and eax hold the return status from 32-bit function.
183 # Note: Do not touch rax from now which hold the return value from IA32 function
184 #
185 pop %rbx
186 pop %rbp
187 pop %rsi
188 pop %rdi
189 popfq
190 #
191 # Switch to orignal GDT and CS. here rsp is pointer to the orignal GDT descriptor.
192 #
193 lgdt (%rsp)
194 #
195 # drop GDT descriptor in stack
196 #
197 addq $0x10, %rsp
198 #
199 # switch to orignal CS and GDTR
200 #
201 pop %r9 # get CS
202 shl $32, %r9 # rcx[32..47] <- Cs
203 lea ReturnToLongMode(%rip), %rcx
204 orq %r9, %rcx
205 push %rcx
206 .byte 0xcb # retf
207 ReturnToLongMode:
208 #
209 # Reload original DS/ES/SS
210 #
211 pop %rcx
212 movq %rcx, %ds
213 movq %rcx, %es
214 movq %rcx, %ss
215 ret
216