[mirror_edk2.git] / MdePkg / Library / BaseLib / Ia32 / Thunk16.asm

;------------------------------------------------------------------------------\r
;\r
; Copyright (c) 2006, Intel Corporation\r
; All rights reserved. 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
    .model  flat,C\r
\r
EXTERNDEF   C   m16Start:BYTE\r
EXTERNDEF   C   m16Size:WORD\r
EXTERNDEF   C   mThunk16Attr:WORD\r
EXTERNDEF   C   m16Gdt:WORD\r
EXTERNDEF   C   m16GdtrBase:WORD\r
EXTERNDEF   C   mTransition:WORD\r
\r
;\r
; Here is the layout of the real mode stack. _ToUserCode() is responsible for\r
; loading all these registers from real mode stack.\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
    .const\r
\r
;\r
; These are global constant to convey information to C code.\r
;\r
m16Size         DW      InternalAsmThunk16 - m16Start\r
mThunk16Attr    DW      _ThunkAttr - m16Start\r
m16Gdt          DW      _NullSegDesc - 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
            DD      ?\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
    push    ss\r
    push    cs\r
    DB      66h\r
    call    @Base                       ; push eip\r
@Base:\r
    pushf                               ; pushfd actually\r
    cli                                 ; disable interrupts\r
    push    gs\r
    push    fs\r
    push    es\r
    push    ds\r
    pushaw                              ; pushad actually\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
    mov     eax, ss\r
    DB      67h\r
    lea     bp, [esp + sizeof (IA32_REGS)]\r
    mov     word ptr (IA32_REGS ptr [esi - sizeof (IA32_REGS)])._ESP, bp\r
    mov     ebx, (IA32_REGS ptr [esi - sizeof (IA32_REGS)])._EIP\r
    shl     ax, 4                       ; shl eax, 4\r
    add     bp, ax                      ; add ebp, eax\r
    DB      66h, 0b8h                   ; mov eax, imm32\r
SavedCr4    DD      ?\r
    mov     cr4, eax\r
    DB      66h\r
    lgdt    fword ptr cs:[edi + (SavedGdt - @Base)]\r
    DB      66h, 0b8h                   ; mov eax, imm32\r
SavedCr0    DD      ?\r
    mov     cr0, eax\r
    DB      0b8h                        ; mov ax, imm16\r
SavedSs     DW      ?\r
    mov     ss, eax\r
    DB      66h, 0bch                   ; mov esp, imm32\r
SavedEsp    DD      ?\r
    DB      66h\r
    retf                                ; return to protected mode\r
_BackFromUserCode   ENDP\r
\r
_EntryPoint DD      _ToUserCode - m16Start\r
            DW      8h\r
_16Idtr     FWORD   (1 SHL 10) - 1\r
_16Gdtr     LABEL   FWORD\r
            DW      GdtEnd - _NullSegDesc - 1\r
_16GdtrBase DD      _NullSegDesc\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     edx, ss\r
    mov     ss, ecx                     ; set new segment selectors\r
    mov     ds, ecx\r
    mov     es, ecx\r
    mov     fs, ecx\r
    mov     gs, ecx\r
    mov     cr0, eax\r
    mov     cr4, ebp                    ; real mode starts at next instruction\r
    mov     ss, esi                     ; set up 16-bit stack segment\r
    xchg    sp, bx                      ; set up 16-bit stack pointer\r
    DB      66h\r
    call    @Base                       ; push eip\r
@Base:\r
    pop     bp                          ; ebp <- address of @Base\r
    DB      67h                         ; address size override\r
    push    [esp + sizeof (IA32_REGS) + 2]\r
    lea     eax, [esi + (@RealMode - @Base)]\r
    push    eax\r
    retf\r
@RealMode:\r
    mov     cs:[esi + (SavedSs - @Base)], edx\r
    mov     cs:[esi + (SavedEsp - @Base)], bx\r
    DB      66h\r
    lidt    fword ptr cs:[esi + (_16Idtr - @Base)]\r
    popaw                               ; popad actually\r
    pop     ds\r
    pop     es\r
    pop     fs\r
    pop     gs\r
    popf                                ; popfd\r
    DB      66h\r
    retf                                ; transfer control to user code\r
_ToUserCode ENDP\r
\r
_NullSegDesc    DQ      0\r
_16CsDesc       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
_16DsDesc       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
GdtEnd          LABEL   QWORD\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    ebp ebx esi edi ds  es  fs  gs\r
    mov     esi, [esp + 36]             ; esi <- RegSet\r
    movzx   edx, (IA32_REGS ptr [esi])._SS\r
    mov     edi, (IA32_REGS ptr [esi])._ESP\r
    add     edi, - (sizeof (IA32_REGS) + 4) ; reserve stack space\r
    mov     ebx, edi                    ; ebx <- stack offset\r
    imul    eax, edx, 16                ; eax <- edx * 16\r
    push    sizeof (IA32_REGS) / 4\r
    add     edi, eax                    ; edi <- linear address of 16-bit stack\r
    pop     ecx\r
    rep     movsd                       ; copy RegSet\r
    mov     eax, [esp + 40]             ; eax <- address of transition code\r
    mov     esi, edx                    ; esi <- 16-bit stack segment\r
    lea     edx, [eax + (SavedCr0 - m16Start)]\r
    mov     ecx, eax\r
    and     ecx, 0fh\r
    shl     eax, 12\r
    lea     ecx, [ecx + (_BackFromUserCode - m16Start)]\r
    mov     ax, cx\r
    stosd                               ; [edi] <- return address of user code\r
    sgdt    fword ptr [edx + (SavedGdt - SavedCr0)]\r
    sidt    fword ptr [esp + 36]        ; save IDT stack in argument space\r
    mov     eax, cr0\r
    mov     [edx], eax                  ; save CR0 in SavedCr0\r
    and     eax, 7ffffffeh              ; clear PE, PG bits\r
    mov     ebp, cr4\r
    mov     [edx + (SavedCr4 - SavedCr0)], ebp\r
    and     ebp, 300h                   ; clear all but PCE and OSFXSR bits\r
    push    10h\r
    pop     ecx                         ; ecx <- selector for data segments\r
    lgdt    fword ptr [edx + (_16Gdtr - SavedCr0)]\r
    pushfd\r
    call    fword ptr [edx + (_EntryPoint - SavedCr0)]\r
    popfd\r
    lidt    fword ptr [esp + 36]        ; restore protected mode IDTR\r
    lea     eax, [ebp - sizeof (IA32_REGS)]\r
    ret\r
InternalAsmThunk16  ENDP\r
\r
    END\r
Commit	Line	Data
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
	22	.686p\r
	23	.model flat,C\r
	24	\r
97d92bda	25	EXTERNDEF C m16Start:BYTE\r
	26	EXTERNDEF C m16Size:WORD\r
	27	EXTERNDEF C mThunk16Attr:WORD\r
	28	EXTERNDEF C m16Gdt:WORD\r
	29	EXTERNDEF C m16GdtrBase:WORD\r
	30	EXTERNDEF C mTransition:WORD\r
878ddf1f	31	\r
3f566587	32	;\r
	33	; Here is the layout of the real mode stack. _ToUserCode() is responsible for\r
	34	; loading all these registers from real mode stack.\r
	35	;\r
878ddf1f	36	IA32_REGS STRUC 4t\r
	37	_EDI DD ?\r
	38	_ESI DD ?\r
	39	_EBP DD ?\r
	40	_ESP DD ?\r
	41	_EBX DD ?\r
	42	_EDX DD ?\r
	43	_ECX DD ?\r
	44	_EAX DD ?\r
	45	_DS DW ?\r
	46	_ES DW ?\r
	47	_FS DW ?\r
	48	_GS DW ?\r
	49	_EFLAGS DD ?\r
	50	_EIP DD ?\r
	51	_CS DW ?\r
	52	_SS DW ?\r
	53	IA32_REGS ENDS\r
	54	\r
97d92bda	55	.const\r
97d92bda	56	\r
3f566587	57	;\r
	58	; These are global constant to convey information to C code.\r
	59	;\r
bbe4ba81	60	m16Size DW InternalAsmThunk16 - m16Start\r
	61	mThunk16Attr DW _ThunkAttr - m16Start\r
	62	m16Gdt DW _NullSegDesc - m16Start\r
	63	m16GdtrBase DW _16GdtrBase - m16Start\r
	64	mTransition DW _EntryPoint - m16Start\r
97d92bda	65	\r
	66	.code\r
	67	\r
	68	m16Start LABEL BYTE\r
	69	\r
bbe4ba81	70	SavedGdt LABEL FWORD\r
	71	DW ?\r
	72	DD ?\r
3f566587	73	;------------------------------------------------------------------------------\r
	74	; _BackFromUserCode() takes control in real mode after 'retf' has been executed\r
	75	; by user code. It will be shadowed to somewhere in memory below 1MB.\r
	76	;------------------------------------------------------------------------------\r
97d92bda	77	_BackFromUserCode PROC\r
	78	push ss\r
	79	push cs\r
878ddf1f	80	DB 66h\r
97d92bda	81	call @Base ; push eip\r
97d92bda	82	@Base:\r
878ddf1f	83	pushf ; pushfd actually\r
97d92bda	84	cli ; disable interrupts\r
878ddf1f	85	push gs\r
	86	push fs\r
	87	push es\r
	88	push ds\r
	89	pushaw ; pushad actually\r
97d92bda	90	DB 66h, 0bah ; mov edx, imm32\r
	91	_ThunkAttr DD ?\r
	92	test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15\r
	93	jz @1\r
	94	mov eax, 15cd2401h ; mov ax, 2401h & int 15h\r
	95	cli ; disable interrupts\r
	96	jnc @2\r
	97	@1:\r
	98	test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL\r
	99	jz @2\r
	100	in al, 92h\r
	101	or al, 2\r
	102	out 92h, al ; deactivate A20M#\r
	103	@2:\r
878ddf1f	104	mov eax, ss\r
878ddf1f	105	DB 67h\r
97d92bda	106	lea bp, [esp + sizeof (IA32_REGS)]\r
	107	mov word ptr (IA32_REGS ptr [esi - sizeof (IA32_REGS)])._ESP, bp\r
	108	mov ebx, (IA32_REGS ptr [esi - sizeof (IA32_REGS)])._EIP\r
	109	shl ax, 4 ; shl eax, 4\r
	110	add bp, ax ; add ebp, eax\r
	111	DB 66h, 0b8h ; mov eax, imm32\r
	112	SavedCr4 DD ?\r
	113	mov cr4, eax\r
	114	DB 66h\r
bbe4ba81	115	lgdt fword ptr cs:[edi + (SavedGdt - @Base)]\r
97d92bda	116	DB 66h, 0b8h ; mov eax, imm32\r
	117	SavedCr0 DD ?\r
	118	mov cr0, eax\r
	119	DB 0b8h ; mov ax, imm16\r
	120	SavedSs DW ?\r
	121	mov ss, eax\r
	122	DB 66h, 0bch ; mov esp, imm32\r
	123	SavedEsp DD ?\r
878ddf1f	124	DB 66h\r
97d92bda	125	retf ; return to protected mode\r
	126	_BackFromUserCode ENDP\r
	127	\r
bbe4ba81	128	_EntryPoint DD _ToUserCode - m16Start\r
	129	DW 8h\r
	130	_16Idtr FWORD (1 SHL 10) - 1\r
	131	_16Gdtr LABEL FWORD\r
	132	DW GdtEnd - _NullSegDesc - 1\r
	133	_16GdtrBase DD _NullSegDesc\r
97d92bda	134	\r
3f566587	135	;------------------------------------------------------------------------------\r
	136	; _ToUserCode() takes control in real mode before passing control to user code.\r
	137	; It will be shadowed to somewhere in memory below 1MB.\r
	138	;------------------------------------------------------------------------------\r
97d92bda	139	_ToUserCode PROC\r
	140	mov edx, ss\r
	141	mov ss, ecx ; set new segment selectors\r
	142	mov ds, ecx\r
	143	mov es, ecx\r
	144	mov fs, ecx\r
	145	mov gs, ecx\r
	146	mov cr0, eax\r
	147	mov cr4, ebp ; real mode starts at next instruction\r
	148	mov ss, esi ; set up 16-bit stack segment\r
	149	xchg sp, bx ; set up 16-bit stack pointer\r
	150	DB 66h\r
	151	call @Base ; push eip\r
	152	@Base:\r
bbe4ba81	153	pop bp ; ebp <- address of @Base\r
18c319ae	154	DB 67h ; address size override\r
18c319ae	155	push [esp + sizeof (IA32_REGS) + 2]\r
bbe4ba81	156	lea eax, [esi + (@RealMode - @Base)]\r
18c319ae	157	push eax\r
	158	retf\r
	159	@RealMode:\r
bbe4ba81	160	mov cs:[esi + (SavedSs - @Base)], edx\r
bbe4ba81	161	mov cs:[esi + (SavedEsp - @Base)], bx\r
97d92bda	162	DB 66h\r
bbe4ba81	163	lidt fword ptr cs:[esi + (_16Idtr - @Base)]\r
97d92bda	164	popaw ; popad actually\r
	165	pop ds\r
	166	pop es\r
	167	pop fs\r
	168	pop gs\r
	169	popf ; popfd\r
	170	DB 66h\r
	171	retf ; transfer control to user code\r
	172	_ToUserCode ENDP\r
	173	\r
	174	_NullSegDesc DQ 0\r
	175	_16CsDesc LABEL QWORD\r
	176	DW -1\r
	177	DW 0\r
	178	DB 0\r
	179	DB 9bh\r
	180	DB 8fh ; 16-bit segment, 4GB limit\r
	181	DB 0\r
	182	_16DsDesc LABEL QWORD\r
	183	DW -1\r
	184	DW 0\r
	185	DB 0\r
	186	DB 93h\r
	187	DB 8fh ; 16-bit segment, 4GB limit\r
	188	DB 0\r
	189	GdtEnd LABEL QWORD\r
	190	\r
3f566587	191	;------------------------------------------------------------------------------\r
	192	; IA32_REGISTER_SET *\r
	193	; EFIAPI\r
	194	; InternalAsmThunk16 (\r
	195	; IN IA32_REGISTER_SET *RegisterSet,\r
	196	; IN OUT VOID *Transition\r
	197	; );\r
	198	;------------------------------------------------------------------------------\r
97d92bda	199	InternalAsmThunk16 PROC USES ebp ebx esi edi ds es fs gs\r
	200	mov esi, [esp + 36] ; esi <- RegSet\r
	201	movzx edx, (IA32_REGS ptr [esi])._SS\r
	202	mov edi, (IA32_REGS ptr [esi])._ESP\r
	203	add edi, - (sizeof (IA32_REGS) + 4) ; reserve stack space\r
	204	mov ebx, edi ; ebx <- stack offset\r
	205	imul eax, edx, 16 ; eax <- edx * 16\r
	206	push sizeof (IA32_REGS) / 4\r
	207	add edi, eax ; edi <- linear address of 16-bit stack\r
	208	pop ecx\r
	209	rep movsd ; copy RegSet\r
	210	mov eax, [esp + 40] ; eax <- address of transition code\r
	211	mov esi, edx ; esi <- 16-bit stack segment\r
bbe4ba81	212	lea edx, [eax + (SavedCr0 - m16Start)]\r
97d92bda	213	mov ecx, eax\r
	214	and ecx, 0fh\r
	215	shl eax, 12\r
bbe4ba81	216	lea ecx, [ecx + (_BackFromUserCode - m16Start)]\r
97d92bda	217	mov ax, cx\r
97d92bda	218	stosd ; [edi] <- return address of user code\r
bbe4ba81	219	sgdt fword ptr [edx + (SavedGdt - SavedCr0)]\r
97d92bda	220	sidt fword ptr [esp + 36] ; save IDT stack in argument space\r
	221	mov eax, cr0\r
	222	mov [edx], eax ; save CR0 in SavedCr0\r
	223	and eax, 7ffffffeh ; clear PE, PG bits\r
	224	mov ebp, cr4\r
bbe4ba81	225	mov [edx + (SavedCr4 - SavedCr0)], ebp\r
97d92bda	226	and ebp, 300h ; clear all but PCE and OSFXSR bits\r
	227	push 10h\r
	228	pop ecx ; ecx <- selector for data segments\r
bbe4ba81	229	lgdt fword ptr [edx + (_16Gdtr - SavedCr0)]\r
18c319ae	230	pushfd\r
bbe4ba81	231	call fword ptr [edx + (_EntryPoint - SavedCr0)]\r
18c319ae	232	popfd\r
878ddf1f	233	lidt fword ptr [esp + 36] ; restore protected mode IDTR\r
97d92bda	234	lea eax, [ebp - sizeof (IA32_REGS)]\r
878ddf1f	235	ret\r
	236	InternalAsmThunk16 ENDP\r
	237	\r
	238	END\r