[mirror_edk2.git] / EdkCompatibilityPkg / Foundation / Library / Thunk16 / Ia32 / Thunk16.asm

;*****************************************************************************\r
;*\r
;*   Copyright (c) 2006 - 2007, 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
    .686p\r
\r
EXTERNDEF   C   mCode16Size:DWORD\r
\r
CONST   SEGMENT FLAT    "DATA"  READONLY\r
\r
mCode16Size     DD      _TEXT16SIZE\r
\r
CONST   ENDS\r
\r
_DATA   SEGMENT FLAT    "DATA"\r
\r
NullSegSel      DQ      0\r
_16BitCsSel     LABEL   QWORD\r
                DW      -1\r
                DW      0\r
                DB      0\r
                DB      9bh\r
                DB      8fh             ; 16-bit segment\r
                DB      0\r
_16BitSsSel     LABEL   QWORD\r
                DW      -1\r
                DW      0\r
                DB      0\r
                DB      93h\r
                DB      8fh            ; 16-bit segment\r
                DB      0\r
\r
_16Gdtr         LABEL   FWORD\r
                DW      $ - offset NullSegSel - 1\r
                DD      offset NullSegSel\r
\r
_DATA   ENDS\r
\r
_TEXT   SEGMENT FLAT    "CODE"  PARA\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     DD      ?\r
_EIP        DD      ?\r
_CS         DW      ?\r
_SS         DW      ?\r
IA32_REGS   ENDS\r
\r
_STK16      STRUC   1t\r
RetEip      DD      ?\r
RetCs       DW      ?\r
ThunkFlags  DW      ?\r
SavedEsp    DD      ?\r
SavedSs     DW      ?\r
SavedGdtr   FWORD   ?\r
SavedCr0    DD      ?\r
SavedCr4    DD      ?\r
_STK16      ENDS\r
\r
    ASSUME  ds:_DATA\r
\r
__Thunk16   PROC    USES    ebp ebx esi edi ds  es  fs  gs\r
    ASSUME  esi:PTR IA32_REGS\r
    mov     esi, [esp + 36]\r
    movzx   edx, [esi]._SS\r
    mov     edi, [esi]._ESP\r
    add     edi, - sizeof (_STK16) - sizeof (IA32_REGS)\r
    push    edi                         ; save stack offset\r
    imul    eax, edx, 16                ; eax <- edx*16\r
    add     edi, eax                    ; edi <- linear address of 16-bit stack\r
    push    sizeof (IA32_REGS) / 4\r
    pop     ecx\r
    rep     movsd                       ; copy context to 16-bit stack\r
    pop     ebx                         ; ebx <- 16-bit stack offset\r
    mov     eax, offset @F              ; return offset\r
    stosd\r
    mov     eax, cs                     ; return segment\r
    stosw\r
    mov     eax, [esp + 40]             ; THUNK flags\r
    stosw\r
    mov     eax, esp\r
    stosd                               ; save esp\r
    mov     eax, ss                     ; save ss\r
    stosw\r
    sgdt    fword ptr [edi]             ; save GDTR\r
    sidt    fword ptr [esp + 36]        ; save IDTR\r
    mov     esi, cr0\r
    mov     [edi + 6], esi              ; save CR0\r
    and     esi, NOT 80000001h          ; esi <- CR0 to set\r
    mov     eax, cr4\r
    mov     [edi + 10], eax             ; save CR4\r
    and     al, NOT 30h                 ; clear PAE & PSE\r
    mov     edi, edx                    ; edi <- 16-bit stack segment\r
    mov     edx, [esp + 44]\r
    shl     edx, 16\r
    push    edx\r
    pop     edx\r
    mov     dx, _16BitSsSel - NullSegSel\r
    lgdt    _16Gdtr                     ; load 16-bit GDTR\r
    DB      0eah\r
    DD      offset @16Bit\r
    DW      _16BitCsSel - NullSegSel    ; jmp far 8:@16Bit\r
@16Bit:\r
    mov     ss, dx\r
    mov     cr0, esi                    ; disable protected mode\r
    mov     cr4, eax                    ; disable PAE & PSE\r
    db      67h, 0FFh, 06Ch, 024h, 0FCh ; jmp     dword ptr [esp-4]\r
@@:\r
    mov     eax, ss\r
    shl     eax, 4\r
    add     eax, esp                    ; eax <- address of 16-bit stack\r
    lss     esp, fword ptr (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedEsp\r
    lidt    fword ptr [esp + 36]        ; restore IDTR\r
    ret\r
__Thunk16   ENDP\r
\r
_TEXT   ENDS\r
\r
_TEXT16 SEGMENT USE16   "CODE"  PARA\r
\r
_Code16Addr PROC    C\r
_Code16Addr ENDP\r
\r
RealMode    PROC\r
    mov     ss, di                      ; set up stack\r
    mov     esp, ebx\r
    lidt    fword ptr cs:[_16Idtr - _Code16Addr]\r
    popad\r
    pop     ds\r
    pop     es\r
    pop     fs\r
    pop     gs\r
    add     sp, 4                       ; skip EFlags\r
    test    (_STK16 ptr [esp + 8]).ThunkFlags, 1\r
    jz      @F\r
    pushf\r
@@:\r
    push    cs\r
;    push    @FarCallRet - _Code16Addr\r
    DB      68h                         ; push /iw\r
    DW      @FarCallRet - _Code16Addr\r
    jz      @F\r
    jmp     fword ptr [esp + 6]\r
@@:\r
    jmp     fword ptr [esp + 4]\r
@FarCallRet:\r
    pushfd\r
    push    gs\r
    push    fs\r
    push    es\r
    push    ds\r
    pushad\r
    cli\r
    DB      66h\r
    lgdt    (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedGdtr\r
    mov     eax, (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedCr4\r
    mov     cr4, eax\r
    mov     eax, (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedCr0\r
    mov     cr0, eax                    ; restore CR0\r
    jmp     fword ptr (_STK16 ptr [esp + sizeof (IA32_REGS)]).RetEip\r
RealMode    ENDP\r
\r
_16Idtr     FWORD   (1 SHL 10) - 1\r
\r
_TEXT16END:\r
\r
_TEXT16SIZE = _TEXT16END - _Code16Addr\r
\r
_TEXT16 ENDS\r
\r
    END\r
Commit	Line	Data
3eb9473e	1	;*****************************************************************************\r
3eb9473e	2	;*\r
4ea9375a HT	3	;* Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR>\r
4ea9375a HT	4	;* This program and the accompanying materials \r
3eb9473e	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