[mirror_edk2.git] / EdkCompatibilityPkg / Foundation / Library / EdkIIGlueLib / Library / BaseLib / X64 / Thunk16.asm

; Copyright (c) 2004 - 2011, Intel Corporation. All rights reserved.<BR>\r
; This program and the accompanying materials                          \r
; are licensed and made available under the terms and conditions of the BSD License         \r
; which accompanies this distribution.  The full text of the license may be found at        \r
; http://opensource.org/licenses/bsd-license.php                                            \r
;                                                                                           \r
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     \r
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.    \r
;\r
; Module Name:\r
;\r
;   Thunk.asm\r
;\r
; Abstract:\r
;\r
;   Real mode thunk\r
;\r
;------------------------------------------------------------------------------\r
\r
EXTERNDEF   m16Start:BYTE\r
EXTERNDEF   m16Size:WORD\r
EXTERNDEF   mThunk16Attr:WORD\r
EXTERNDEF   m16Gdt:WORD\r
EXTERNDEF   m16GdtrBase:WORD\r
EXTERNDEF   mTransition:WORD\r
\r
THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15     EQU 2\r
THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL   EQU 4\r
\r
IA32_REGS   STRUC   4t\r
_EDI        DD      ?\r
_ESI        DD      ?\r
_EBP        DD      ?\r
_ESP        DD      ?\r
_EBX        DD      ?\r
_EDX        DD      ?\r
_ECX        DD      ?\r
_EAX        DD      ?\r
_DS         DW      ?\r
_ES         DW      ?\r
_FS         DW      ?\r
_GS         DW      ?\r
_EFLAGS     DQ      ?\r
_EIP        DD      ?\r
_CS         DW      ?\r
_SS         DW      ?\r
IA32_REGS   ENDS\r
\r
    .const\r
\r
m16Size         DW      InternalAsmThunk16 - m16Start\r
mThunk16Attr    DW      _ThunkAttr - m16Start\r
m16Gdt          DW      _NullSeg - m16Start\r
m16GdtrBase     DW      _16GdtrBase - m16Start\r
mTransition     DW      _EntryPoint - m16Start\r
\r
    .code\r
\r
m16Start    LABEL   BYTE\r
\r
SavedGdt    LABEL   FWORD\r
            DW      ?\r
            DQ      ?\r
\r
;------------------------------------------------------------------------------\r
; _BackFromUserCode() takes control in real mode after 'retf' has been executed\r
; by user code. It will be shadowed to somewhere in memory below 1MB.\r
;------------------------------------------------------------------------------\r
_BackFromUserCode   PROC\r
    ;\r
    ; The order of saved registers on the stack matches the order they appears\r
    ; in IA32_REGS structure. This facilitates wrapper function to extract them\r
    ; into that structure.\r
    ;\r
    ; Some instructions for manipulation of segment registers have to be written\r
    ; in opcode since 64-bit MASM prevents accesses to those registers.\r
    ;\r
    DB      16h                         ; push ss\r
    DB      0eh                         ; push cs\r
    DB      66h\r
    call    @Base                       ; push eip\r
@Base:\r
    DB      66h\r
    push    0                           ; reserved high order 32 bits of EFlags\r
    pushf                               ; pushfd actually\r
    cli                                 ; disable interrupts\r
    push    gs\r
    push    fs\r
    DB      6                           ; push es\r
    DB      1eh                         ; push ds\r
    DB      66h, 60h                    ; pushad\r
    DB      66h, 0bah                   ; mov edx, imm32\r
_ThunkAttr  DD      ?\r
    test    dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15\r
    jz      @1\r
    mov     eax, 15cd2401h              ; mov ax, 2401h & int 15h\r
    cli                                 ; disable interrupts\r
    jnc     @2\r
@1:\r
    test    dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL\r
    jz      @2\r
    in      al, 92h\r
    or      al, 2\r
    out     92h, al                     ; deactivate A20M#\r
@2:\r
    xor     ax, ax                      ; xor eax, eax\r
    mov     eax, ss                     ; mov ax, ss\r
    lea     bp, [esp + sizeof (IA32_REGS)]\r
    ;\r
    ; rsi in the following 2 instructions is indeed bp in 16-bit code\r
    ;\r
    mov     word ptr (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._ESP, bp\r
    DB      66h\r
    mov     ebx, (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._EIP\r
    shl     ax, 4                       ; shl eax, 4\r
    add     bp, ax                      ; add ebp, eax\r
    mov     ax, cs\r
    shl     ax, 4\r
    lea     ax, [eax + ebx + (@64BitCode - @Base)]\r
    DB      66h, 2eh, 89h, 87h          ; mov cs:[bx + (@64Eip - @Base)], eax\r
    DW      @64Eip - @Base\r
    DB      66h, 0b8h                   ; mov eax, imm32\r
SavedCr4    DD      ?\r
    mov     cr4, rax\r
    ;\r
    ; rdi in the instruction below is indeed bx in 16-bit code\r
    ;\r
    DB      66h, 2eh                    ; 2eh is "cs:" segment override\r
    lgdt    fword ptr [rdi + (SavedGdt - @Base)]\r
    DB      66h\r
    mov     ecx, 0c0000080h\r
    rdmsr\r
    or      ah, 1\r
    wrmsr\r
    DB      66h, 0b8h                   ; mov eax, imm32\r
SavedCr0    DD      ?\r
    mov     cr0, rax\r
    DB      66h, 0eah                   ; jmp far cs:@64Bit\r
@64Eip      DD      ?\r
SavedCs     DW      ?\r
@64BitCode:\r
    db      090h \r
    db      067h, 0bch                 ; mov esp, imm32\r
SavedSp     DD   ?                     ; restore stack\r
    nop\r
    ret\r
_BackFromUserCode   ENDP\r
\r
_EntryPoint DD      _ToUserCode - m16Start\r
            DW      CODE16\r
_16Gdtr     LABEL   FWORD\r
            DW      GDT_SIZE - 1\r
_16GdtrBase DQ      _NullSeg\r
_16Idtr     FWORD   (1 SHL 10) - 1\r
\r
;------------------------------------------------------------------------------\r
; _ToUserCode() takes control in real mode before passing control to user code.\r
; It will be shadowed to somewhere in memory below 1MB.\r
;------------------------------------------------------------------------------\r
_ToUserCode PROC\r
    mov     ss, edx                     ; set new segment selectors\r
    mov     ds, edx\r
    mov     es, edx\r
    mov     fs, edx\r
    mov     gs, edx\r
    DB      66h\r
    mov     ecx, 0c0000080h\r
    mov     cr0, rax                    ; real mode starts at next instruction\r
    rdmsr\r
    and     ah, NOT 1\r
    wrmsr\r
    mov     cr4, rbp\r
    mov     ss, esi                     ; set up 16-bit stack segment\r
    mov     sp, bx                      ; set up 16-bit stack pointer\r
    DB      66h                         ; make the following call 32-bit\r
    call    @Base                       ; push eip\r
@Base:\r
    pop     bp                          ; ebp <- address of @Base\r
    push    [esp + sizeof (IA32_REGS) + 2]\r
    lea     eax, [rsi + (@RealMode - @Base)]    ; rsi is "bp" in 16-bit code\r
    push    rax\r
    retf                                ; execution begins at next instruction\r
@RealMode:\r
    DB      66h, 2eh                    ; CS and operand size override\r
    lidt    fword ptr [rsi + (_16Idtr - @Base)]\r
    DB      66h, 61h                    ; popad\r
    DB      1fh                         ; pop ds\r
    DB      07h                         ; pop es\r
    pop     fs\r
    pop     gs\r
    popf                                ; popfd\r
    lea     sp, [esp + 4]               ; skip high order 32 bits of EFlags\r
    DB      66h                         ; make the following retf 32-bit\r
    retf                                ; transfer control to user code\r
_ToUserCode ENDP\r
\r
CODE16  = _16Code - $\r
DATA16  = _16Data - $\r
DATA32  = _32Data - $\r
\r
_NullSeg    DQ      0\r
_16Code     LABEL   QWORD\r
            DW      -1\r
            DW      0\r
            DB      0\r
            DB      9bh\r
            DB      8fh                 ; 16-bit segment, 4GB limit\r
            DB      0\r
_16Data     LABEL   QWORD\r
            DW      -1\r
            DW      0\r
            DB      0\r
            DB      93h\r
            DB      8fh                 ; 16-bit segment, 4GB limit\r
            DB      0\r
_32Data     LABEL   QWORD\r
            DW      -1\r
            DW      0\r
            DB      0\r
            DB      93h\r
            DB      0cfh                ; 16-bit segment, 4GB limit\r
            DB      0\r
\r
GDT_SIZE = $ - _NullSeg\r
\r
;------------------------------------------------------------------------------\r
; IA32_REGISTER_SET *\r
; EFIAPI\r
; InternalAsmThunk16 (\r
;   IN      IA32_REGISTER_SET         *RegisterSet,\r
;   IN OUT  VOID                      *Transition\r
;   );\r
;------------------------------------------------------------------------------\r
InternalAsmThunk16  PROC    USES    rbp rbx rsi rdi\r
    mov     rbx, ds\r
    push    rbx          ; Save ds segment register on the stack\r
    mov     rbx, es\r
    push    rbx          ; Save es segment register on the stack\r
    mov     rbx, ss\r
    push    rbx          ; Save ss segment register on the stack\r
    \r
    push    fs\r
    push    gs\r
    mov     rsi, rcx\r
    movzx   r8d, (IA32_REGS ptr [rsi])._SS\r
    mov     edi, (IA32_REGS ptr [rsi])._ESP\r
    lea     rdi, [edi - (sizeof (IA32_REGS) + 4)]\r
    imul    eax, r8d, 16                ; eax <- r8d(stack segment) * 16\r
    mov     ebx, edi                    ; ebx <- stack for 16-bit code\r
    push    sizeof (IA32_REGS) / 4\r
    add     edi, eax                    ; edi <- linear address of 16-bit stack\r
    pop     rcx\r
    rep     movsd                       ; copy RegSet\r
    lea     ecx, [rdx + (SavedCr4 - m16Start)]\r
    mov     eax, edx                    ; eax <- transition code address\r
    and     edx, 0fh\r
    shl     eax, 12                     ; segment address in high order 16 bits\r
    lea     ax, [rdx + (_BackFromUserCode - m16Start)]  ; offset address\r
    stosd                               ; [edi] <- return address of user code\r
    sgdt    fword ptr [rcx + (SavedGdt - SavedCr4)]\r
    sidt    fword ptr [rsp + 50h]       ; save IDT stack in argument space\r
    mov     rax, cr0\r
    mov     [rcx + (SavedCr0 - SavedCr4)], eax\r
    and     eax, 7ffffffeh              ; clear PE, PG bits\r
    mov     rbp, cr4\r
    mov     [rcx], ebp                  ; save CR4 in SavedCr4\r
    and     ebp, 300h                   ; clear all but PCE and OSFXSR bits\r
    mov     esi, r8d                    ; esi <- 16-bit stack segment\r
    DB      6ah, DATA32                 ; push DATA32\r
    pop     rdx                         ; rdx <- 32-bit data segment selector\r
    lgdt    fword ptr [rcx + (_16Gdtr - SavedCr4)]\r
    mov     ss, edx\r
    pushfq\r
    lea     edx, [rdx + DATA16 - DATA32]\r
    lea     r8, @RetFromRealMode\r
    push    r8\r
    mov     r8d, cs\r
    mov     [rcx + (SavedCs - SavedCr4)], r8w\r
    mov     [rcx + (SavedSp - SavedCr4)], esp\r
    jmp     fword ptr [rcx + (_EntryPoint - SavedCr4)]\r
@RetFromRealMode:\r
    popfq\r
    lidt    fword ptr [rsp + 50h]       ; restore protected mode IDTR\r
    lea     eax, [rbp - sizeof (IA32_REGS)]\r
    pop     gs\r
    pop     fs\r
    pop     rbx\r
    mov     ss, rbx\r
    pop     rbx\r
    mov     es, rbx\r
    pop     rbx\r
    mov     ds, rbx\r
    ret\r
InternalAsmThunk16  ENDP\r
\r
    END\r
Commit	Line	Data
0249feb8	1	; Copyright (c) 2004 - 2011, Intel Corporation. All rights reserved.<BR>\r
2c7e5c2f	2	; This program and the accompanying materials \r
3eb9473e	3	; are licensed and made available under the terms and conditions of the BSD License \r
	4	; which accompanies this distribution. The full text of the license may be found at \r
	5	; http://opensource.org/licenses/bsd-license.php \r
	6	; \r
	7	; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r
	8	; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r
	9	;\r
	10	; Module Name:\r
	11	;\r
	12	; Thunk.asm\r
	13	;\r
	14	; Abstract:\r
	15	;\r
	16	; Real mode thunk\r
	17	;\r
	18	;------------------------------------------------------------------------------\r
	19	\r
	20	EXTERNDEF m16Start:BYTE\r
	21	EXTERNDEF m16Size:WORD\r
	22	EXTERNDEF mThunk16Attr:WORD\r
	23	EXTERNDEF m16Gdt:WORD\r
	24	EXTERNDEF m16GdtrBase:WORD\r
	25	EXTERNDEF mTransition:WORD\r
	26	\r
	27	THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 EQU 2\r
	28	THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL EQU 4\r
	29	\r
	30	IA32_REGS STRUC 4t\r
	31	_EDI DD ?\r
	32	_ESI DD ?\r
	33	_EBP DD ?\r
	34	_ESP DD ?\r
	35	_EBX DD ?\r
	36	_EDX DD ?\r
	37	_ECX DD ?\r
	38	_EAX DD ?\r
	39	_DS DW ?\r
	40	_ES DW ?\r
	41	_FS DW ?\r
	42	_GS DW ?\r
	43	_EFLAGS DQ ?\r
	44	_EIP DD ?\r
	45	_CS DW ?\r
	46	_SS DW ?\r
	47	IA32_REGS ENDS\r
	48	\r
	49	.const\r
	50	\r
	51	m16Size DW InternalAsmThunk16 - m16Start\r
	52	mThunk16Attr DW _ThunkAttr - m16Start\r
	53	m16Gdt DW _NullSeg - m16Start\r
	54	m16GdtrBase DW _16GdtrBase - m16Start\r
	55	mTransition DW _EntryPoint - m16Start\r
	56	\r
	57	.code\r
	58	\r
	59	m16Start LABEL BYTE\r
	60	\r
	61	SavedGdt LABEL FWORD\r
	62	DW ?\r
	63	DQ ?\r
	64	\r
	65	;------------------------------------------------------------------------------\r
	66	; _BackFromUserCode() takes control in real mode after 'retf' has been executed\r
67	; by user code. It will be shadowed to somewhere in memory below 1MB.\r
68	;------------------------------------------------------------------------------\r
69	_BackFromUserCode PROC\r
70	;\r
71	; The order of saved registers on the stack matches the order they appears\r
72	; in IA32_REGS structure. This facilitates wrapper function to extract them\r
73	; into that structure.\r
74	;\r
75	; Some instructions for manipulation of segment registers have to be written\r
76	; in opcode since 64-bit MASM prevents accesses to those registers.\r
77	;\r
78	DB 16h ; push ss\r
79	DB 0eh ; push cs\r
80	DB 66h\r
81	call @Base ; push eip\r
82	@Base:\r
83	DB 66h\r
84	push 0 ; reserved high order 32 bits of EFlags\r
85	pushf ; pushfd actually\r
86	cli ; disable interrupts\r
87	push gs\r
88	push fs\r
89	DB 6 ; push es\r
90	DB 1eh ; push ds\r
91	DB 66h, 60h ; pushad\r
92	DB 66h, 0bah ; mov edx, imm32\r
93	_ThunkAttr DD ?\r
94	test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15\r
95	jz @1\r
96	mov eax, 15cd2401h ; mov ax, 2401h & int 15h\r
97	cli ; disable interrupts\r
98	jnc @2\r
99	@1:\r
100	test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL\r
101	jz @2\r
102	in al, 92h\r
103	or al, 2\r
104	out 92h, al ; deactivate A20M#\r
105	@2:\r
0249feb8 LG	106	xor ax, ax ; xor eax, eax\r
0249feb8 LG	107	mov eax, ss ; mov ax, ss\r
3eb9473e	108	lea bp, [esp + sizeof (IA32_REGS)]\r
	109	;\r
	110	; rsi in the following 2 instructions is indeed bp in 16-bit code\r
	111	;\r
	112	mov word ptr (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._ESP, bp\r
	113	DB 66h\r
	114	mov ebx, (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._EIP\r
	115	shl ax, 4 ; shl eax, 4\r
	116	add bp, ax ; add ebp, eax\r
	117	mov ax, cs\r
	118	shl ax, 4\r
	119	lea ax, [eax + ebx + (@64BitCode - @Base)]\r
	120	DB 66h, 2eh, 89h, 87h ; mov cs:[bx + (@64Eip - @Base)], eax\r
	121	DW @64Eip - @Base\r
	122	DB 66h, 0b8h ; mov eax, imm32\r
	123	SavedCr4 DD ?\r
	124	mov cr4, rax\r
	125	;\r
	126	; rdi in the instruction below is indeed bx in 16-bit code\r
	127	;\r
	128	DB 66h, 2eh ; 2eh is "cs:" segment override\r
	129	lgdt fword ptr [rdi + (SavedGdt - @Base)]\r
	130	DB 66h\r
	131	mov ecx, 0c0000080h\r
	132	rdmsr\r
	133	or ah, 1\r
	134	wrmsr\r
	135	DB 66h, 0b8h ; mov eax, imm32\r
	136	SavedCr0 DD ?\r
	137	mov cr0, rax\r
	138	DB 66h, 0eah ; jmp far cs:@64Bit\r
	139	@64Eip DD ?\r
	140	SavedCs DW ?\r
	141	@64BitCode:\r
1e437167	142	db 090h \r
	143	db 067h, 0bch ; mov esp, imm32\r
	144	SavedSp DD ? ; restore stack\r
	145	nop\r
3eb9473e	146	ret\r
	147	_BackFromUserCode ENDP\r
	148	\r
	149	_EntryPoint DD _ToUserCode - m16Start\r
	150	DW CODE16\r
	151	_16Gdtr LABEL FWORD\r
	152	DW GDT_SIZE - 1\r
	153	_16GdtrBase DQ _NullSeg\r
	154	_16Idtr FWORD (1 SHL 10) - 1\r
	155	\r
	156	;------------------------------------------------------------------------------\r
	157	; _ToUserCode() takes control in real mode before passing control to user code.\r
	158	; It will be shadowed to somewhere in memory below 1MB.\r
	159	;------------------------------------------------------------------------------\r
	160	_ToUserCode PROC\r
	161	mov ss, edx ; set new segment selectors\r
	162	mov ds, edx\r
	163	mov es, edx\r
	164	mov fs, edx\r
	165	mov gs, edx\r
	166	DB 66h\r
	167	mov ecx, 0c0000080h\r
	168	mov cr0, rax ; real mode starts at next instruction\r
	169	rdmsr\r
	170	and ah, NOT 1\r
	171	wrmsr\r
	172	mov cr4, rbp\r
	173	mov ss, esi ; set up 16-bit stack segment\r
	174	mov sp, bx ; set up 16-bit stack pointer\r
	175	DB 66h ; make the following call 32-bit\r
	176	call @Base ; push eip\r
	177	@Base:\r
	178	pop bp ; ebp <- address of @Base\r
	179	push [esp + sizeof (IA32_REGS) + 2]\r
	180	lea eax, [rsi + (@RealMode - @Base)] ; rsi is "bp" in 16-bit code\r
	181	push rax\r
	182	retf ; execution begins at next instruction\r
	183	@RealMode:\r
	184	DB 66h, 2eh ; CS and operand size override\r
	185	lidt fword ptr [rsi + (_16Idtr - @Base)]\r
	186	DB 66h, 61h ; popad\r
	187	DB 1fh ; pop ds\r
	188	DB 07h ; pop es\r
	189	pop fs\r
	190	pop gs\r
	191	popf ; popfd\r
	192	lea sp, [esp + 4] ; skip high order 32 bits of EFlags\r
	193	DB 66h ; make the following retf 32-bit\r
	194	retf ; transfer control to user code\r
	195	_ToUserCode ENDP\r
	196	\r
	197	CODE16 = _16Code - $\r
	198	DATA16 = _16Data - $\r
	199	DATA32 = _32Data - $\r
	200	\r
	201	_NullSeg DQ 0\r
	202	_16Code LABEL QWORD\r
	203	DW -1\r
	204	DW 0\r
	205	DB 0\r
	206	DB 9bh\r
	207	DB 8fh ; 16-bit segment, 4GB limit\r
	208	DB 0\r
	209	_16Data LABEL QWORD\r
210	DW -1\r
211	DW 0\r
212	DB 0\r
213	DB 93h\r
214	DB 8fh ; 16-bit segment, 4GB limit\r
215	DB 0\r
216	_32Data LABEL QWORD\r
217	DW -1\r
218	DW 0\r
219	DB 0\r
220	DB 93h\r
221	DB 0cfh ; 16-bit segment, 4GB limit\r
222	DB 0\r
223	\r
224	GDT_SIZE = $ - _NullSeg\r
225	\r
226	;------------------------------------------------------------------------------\r
227	; IA32_REGISTER_SET *\r
228	; EFIAPI\r
229	; InternalAsmThunk16 (\r
230	; IN IA32_REGISTER_SET *RegisterSet,\r
231	; IN OUT VOID *Transition\r
232	; );\r
233	;------------------------------------------------------------------------------\r
234	InternalAsmThunk16 PROC USES rbp rbx rsi rdi\r
1e437167	235	mov rbx, ds\r
	236	push rbx ; Save ds segment register on the stack\r
	237	mov rbx, es\r
	238	push rbx ; Save es segment register on the stack\r
	239	mov rbx, ss\r
	240	push rbx ; Save ss segment register on the stack\r
	241	\r
3eb9473e	242	push fs\r
	243	push gs\r
	244	mov rsi, rcx\r
	245	movzx r8d, (IA32_REGS ptr [rsi])._SS\r
	246	mov edi, (IA32_REGS ptr [rsi])._ESP\r
	247	lea rdi, [edi - (sizeof (IA32_REGS) + 4)]\r
	248	imul eax, r8d, 16 ; eax <- r8d(stack segment) * 16\r
	249	mov ebx, edi ; ebx <- stack for 16-bit code\r
	250	push sizeof (IA32_REGS) / 4\r
	251	add edi, eax ; edi <- linear address of 16-bit stack\r
	252	pop rcx\r
	253	rep movsd ; copy RegSet\r
	254	lea ecx, [rdx + (SavedCr4 - m16Start)]\r
	255	mov eax, edx ; eax <- transition code address\r
	256	and edx, 0fh\r
	257	shl eax, 12 ; segment address in high order 16 bits\r
	258	lea ax, [rdx + (_BackFromUserCode - m16Start)] ; offset address\r
	259	stosd ; [edi] <- return address of user code\r
	260	sgdt fword ptr [rcx + (SavedGdt - SavedCr4)]\r
1e437167	261	sidt fword ptr [rsp + 50h] ; save IDT stack in argument space\r
3eb9473e	262	mov rax, cr0\r
	263	mov [rcx + (SavedCr0 - SavedCr4)], eax\r
	264	and eax, 7ffffffeh ; clear PE, PG bits\r
	265	mov rbp, cr4\r
	266	mov [rcx], ebp ; save CR4 in SavedCr4\r
	267	and ebp, 300h ; clear all but PCE and OSFXSR bits\r
	268	mov esi, r8d ; esi <- 16-bit stack segment\r
	269	DB 6ah, DATA32 ; push DATA32\r
	270	pop rdx ; rdx <- 32-bit data segment selector\r
	271	lgdt fword ptr [rcx + (_16Gdtr - SavedCr4)]\r
	272	mov ss, edx\r
	273	pushfq\r
	274	lea edx, [rdx + DATA16 - DATA32]\r
	275	lea r8, @RetFromRealMode\r
	276	push r8\r
	277	mov r8d, cs\r
	278	mov [rcx + (SavedCs - SavedCr4)], r8w\r
1e437167	279	mov [rcx + (SavedSp - SavedCr4)], esp\r
3eb9473e	280	jmp fword ptr [rcx + (_EntryPoint - SavedCr4)]\r
	281	@RetFromRealMode:\r
	282	popfq\r
1e437167	283	lidt fword ptr [rsp + 50h] ; restore protected mode IDTR\r
3eb9473e	284	lea eax, [rbp - sizeof (IA32_REGS)]\r
	285	pop gs\r
	286	pop fs\r
1e437167	287	pop rbx\r
	288	mov ss, rbx\r
	289	pop rbx\r
	290	mov es, rbx\r
	291	pop rbx\r
	292	mov ds, rbx\r
3eb9473e	293	ret\r
	294	InternalAsmThunk16 ENDP\r
	295	\r
	296	END\r