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-rw-r--r--MdePkg/Library/BaseLib/Ia32/Thunk16.nasm81
-rw-r--r--MdePkg/Library/BaseLib/X64/Thunk16.nasm121
2 files changed, 87 insertions, 115 deletions
diff --git a/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm b/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
index c00e3ab078..a1093e0107 100644
--- a/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
+++ b/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
@@ -82,23 +82,24 @@ _BackFromUserCode:
; in IA32_REGS structure. This facilitates wrapper function to extract them
; into that structure.
;
+BITS 16
push ss
push cs
- DB 66h
- call .Base ; push eip
+o32 call dword .Base ; push eip
.Base:
- pushfw ; pushfd actually
+ pushfd
cli ; disable interrupts
push gs
push fs
push es
push ds
- pushaw ; pushad actually
+ pushad
DB 66h, 0bah ; mov edx, imm32
.ThunkAttr: dd 0
test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15
jz .1
- mov eax, 15cd2401h ; mov ax, 2401h & int 15h
+ mov ax, 2401h
+ int 15h
cli ; disable interrupts
jnc .2
.1:
@@ -108,24 +109,17 @@ _BackFromUserCode:
or al, 2
out 92h, al ; deactivate A20M#
.2:
- xor ax, ax ; xor eax, eax
- mov eax, ss ; mov ax, ss
- DB 67h
- lea bp, [esp + IA32_REGS.size]
- ;
- ; esi's in the following 2 instructions are indeed bp in 16-bit code. Fact
- ; is "esi" in 32-bit addressing mode has the same encoding of "bp" in 16-
- ; bit addressing mode.
- ;
- mov [esi - IA32_REGS.size + IA32_REGS._ESP], bp
- mov ebx, [esi - IA32_REGS.size + IA32_REGS._EIP]
- shl ax, 4 ; shl eax, 4
- add bp, ax ; add ebp, eax
+ xor eax, eax
+ mov ax, ss
+ lea ebp, [esp + IA32_REGS.size]
+ mov [bp - IA32_REGS.size + IA32_REGS._ESP], ebp
+ mov bx, [bp - IA32_REGS.size + IA32_REGS._EIP]
+ shl eax, 4 ; shl eax, 4
+ add ebp, eax ; add ebp, eax
DB 66h, 0b8h ; mov eax, imm32
.SavedCr4: DD 0
mov cr4, eax
- DB 66h
- lgdt [cs:edi + (SavedGdt - .Base)]
+o32 lgdt [cs:bx + (SavedGdt - .Base)]
DB 66h, 0b8h ; mov eax, imm32
.SavedCr0: DD 0
mov cr0, eax
@@ -134,8 +128,7 @@ _BackFromUserCode:
mov ss, eax
DB 66h, 0bch ; mov esp, imm32
.SavedEsp DD 0
- DB 66h
- retf ; return to protected mode
+o32 retf ; return to protected mode
_EntryPoint:
DD _ToUserCode - ASM_PFX(m16Start)
@@ -153,45 +146,34 @@ _16GdtrBase:
; It will be shadowed to somewhere in memory below 1MB.
;------------------------------------------------------------------------------
_ToUserCode:
- mov edx, ss
- mov ss, ecx ; set new segment selectors
- mov ds, ecx
- mov es, ecx
- mov fs, ecx
- mov gs, ecx
+BITS 16
+ mov dx, ss
+ mov ss, cx ; set new segment selectors
+ mov ds, cx
+ mov es, cx
+ mov fs, cx
+ mov gs, cx
mov cr0, eax ; real mode starts at next instruction
; which (per SDM) *must* be a far JMP.
DB 0eah
.RealAddr: DW 0, 0
mov cr4, ebp
- mov ss, esi ; set up 16-bit stack segment
- xchg sp, bx ; set up 16-bit stack pointer
-
-; mov bp, [esp + sizeof(IA32_REGS)
- DB 67h
- mov ebp, [esp + IA32_REGS.size] ; BackFromUserCode address from stack
-
-; mov cs:[bp + (_BackFromUserCode.SavedSs - _BackFromUserCode)], dx
- mov [cs:esi + (_BackFromUserCode.SavedSs - _BackFromUserCode)], edx
+ mov ss, si ; set up 16-bit stack segment
+ xchg esp, ebx ; set up 16-bit stack pointer
+ mov bp, [esp + IA32_REGS.size]
+ mov [cs:bp + (_BackFromUserCode.SavedSs - _BackFromUserCode)], dx
+ mov [cs:bp + (_BackFromUserCode.SavedEsp - _BackFromUserCode)], ebx
+ lidt [cs:bp + (_16Idtr - _BackFromUserCode)]
-; mov cs:[bp + (_BackFromUserCode.SavedEsp - _BackFromUserCode)], ebx
- DB 2eh, 66h, 89h, 9eh
- DW _BackFromUserCode.SavedEsp - _BackFromUserCode
-
-; lidt cs:[bp + (_16Idtr - _BackFromUserCode)]
- DB 2eh, 66h, 0fh, 01h, 9eh
- DW _16Idtr - _BackFromUserCode
-
- popaw ; popad actually
+ popad
pop ds
pop es
pop fs
pop gs
- popfw ; popfd
+ popfd
- DB 66h ; Use 32-bit addressing for "retf" below
- retf ; transfer control to user code
+o32 retf ; transfer control to user code
ALIGN 16
_NullSegDesc DQ 0
@@ -221,6 +203,7 @@ GdtEnd:
;------------------------------------------------------------------------------
global ASM_PFX(InternalAsmThunk16)
ASM_PFX(InternalAsmThunk16):
+BITS 32
push ebp
push ebx
push esi
diff --git a/MdePkg/Library/BaseLib/X64/Thunk16.nasm b/MdePkg/Library/BaseLib/X64/Thunk16.nasm
index cabe9d94d1..5fa705998e 100644
--- a/MdePkg/Library/BaseLib/X64/Thunk16.nasm
+++ b/MdePkg/Library/BaseLib/X64/Thunk16.nasm
@@ -80,28 +80,25 @@ _BackFromUserCode:
; in IA32_REGS structure. This facilitates wrapper function to extract them
; into that structure.
;
- ; Some instructions for manipulation of segment registers have to be written
- ; in opcode since 64-bit MASM prevents accesses to those registers.
- ;
- DB 16h ; push ss
- DB 0eh ; push cs
- DB 66h
- call .Base ; push eip
+BITS 16
+ push ss
+ push cs
+o32 call dword .Base ; push eip
.Base:
- DB 66h
- push 0 ; reserved high order 32 bits of EFlags
- pushfw ; pushfd actually
+ push dword 0 ; reserved high order 32 bits of EFlags
+ pushfd
cli ; disable interrupts
push gs
push fs
- DB 6 ; push es
- DB 1eh ; push ds
- DB 66h, 60h ; pushad
+ push es
+ push ds
+ pushad
DB 66h, 0bah ; mov edx, imm32
-.ThunkAttr: dd 0
+.ThunkAttr: dd 0
test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15
jz .1
- mov eax, 15cd2401h ; mov ax, 2401h & int 15h
+ mov ax, 2401h
+ int 15h
cli ; disable interrupts
jnc .2
.1:
@@ -111,43 +108,34 @@ _BackFromUserCode:
or al, 2
out 92h, al ; deactivate A20M#
.2:
- xor ax, ax ; xor eax, eax
- mov eax, ss ; mov ax, ss
- lea bp, [esp + IA32_REGS.size]
- ;
- ; rsi in the following 2 instructions is indeed bp in 16-bit code
- ;
- mov [rsi - IA32_REGS.size + IA32_REGS._ESP], bp
- DB 66h
- mov ebx, [rsi - IA32_REGS.size + IA32_REGS._EIP]
- shl ax, 4 ; shl eax, 4
- add bp, ax ; add ebp, eax
- mov ax, cs
- shl ax, 4
- lea ax, [eax + ebx + (.64BitCode - .Base)]
- DB 66h, 2eh, 89h, 87h ; mov cs:[bx + (.64Eip - .Base)], eax
- DW .64Eip - .Base
+ xor eax, eax
+ mov ax, ss
+ lea ebp, [esp + IA32_REGS.size]
+ mov [bp - IA32_REGS.size + IA32_REGS._ESP], ebp
+ mov ebx, [bp - IA32_REGS.size + IA32_REGS._EIP]
+ shl eax, 4 ; shl eax, 4
+ add ebp, eax ; add ebp, eax
+ mov eax, cs
+ shl eax, 4
+ lea eax, [eax + ebx + (.64BitCode - .Base)]
+ mov [cs:bx + (.64Eip - .Base)], eax
DB 66h, 0b8h ; mov eax, imm32
.SavedCr4: DD 0
- mov cr4, rax
- ;
- ; rdi in the instruction below is indeed bx in 16-bit code
- ;
- DB 66h, 2eh ; 2eh is "cs:" segment override
- lgdt [rdi + (SavedGdt - .Base)]
- DB 66h
+ mov cr4, eax
+o32 lgdt [cs:bx + (SavedGdt - .Base)]
mov ecx, 0c0000080h
rdmsr
or ah, 1
wrmsr
DB 66h, 0b8h ; mov eax, imm32
.SavedCr0: DD 0
- mov cr0, rax
+ mov cr0, eax
DB 66h, 0eah ; jmp far cs:.64Bit
.64Eip: DD 0
.SavedCs: DW 0
.64BitCode:
- db 090h
+BITS 64
+ nop
db 048h, 0bch ; mov rsp, imm64
.SavedSp: DQ 0 ; restore stack
nop
@@ -169,40 +157,40 @@ _16Idtr:
; It will be shadowed to somewhere in memory below 1MB.
;------------------------------------------------------------------------------
_ToUserCode:
- mov ss, edx ; set new segment selectors
- mov ds, edx
- mov es, edx
- mov fs, edx
- mov gs, edx
- DB 66h
+BITS 16
+ mov ss, dx ; set new segment selectors
+ mov ds, dx
+ mov es, dx
+ mov fs, dx
+ mov gs, dx
mov ecx, 0c0000080h
- mov cr0, rax ; real mode starts at next instruction
+ mov cr0, eax ; real mode starts at next instruction
rdmsr
and ah, ~1
wrmsr
- mov cr4, rbp
- mov ss, esi ; set up 16-bit stack segment
- mov sp, bx ; set up 16-bit stack pointer
- DB 66h ; make the following call 32-bit
- call .Base ; push eip
+ mov cr4, ebp
+ mov ss, si ; set up 16-bit stack segment
+ mov esp, ebx ; set up 16-bit stack pointer
+ call dword .Base ; push eip
.Base:
- pop bp ; ebp <- address of .Base
- push qword [esp + IA32_REGS.size + 2]
- lea eax, [rsi + (.RealMode - .Base)] ; rsi is "bp" in 16-bit code
- push rax
+ pop ebp ; ebp <- address of .Base
+ push word [dword esp + IA32_REGS.size + 2]
+ lea ax, [bp + (.RealMode - .Base)]
+ push ax
retf ; execution begins at next instruction
.RealMode:
- DB 66h, 2eh ; CS and operand size override
- lidt [rsi + (_16Idtr - .Base)]
- DB 66h, 61h ; popad
- DB 1fh ; pop ds
- DB 07h ; pop es
+
+o32 lidt [cs:bp + (_16Idtr - .Base)]
+
+ popad
+ pop ds
+ pop es
pop fs
pop gs
- popfw ; popfd
- lea sp, [esp + 4] ; skip high order 32 bits of EFlags
- DB 66h ; make the following retf 32-bit
- retf ; transfer control to user code
+ popfd
+ lea esp, [esp + 4] ; skip high order 32 bits of EFlags
+
+o32 retf ; transfer control to user code
ALIGN 8
@@ -245,6 +233,7 @@ GDT_SIZE equ $ - _NullSeg
;------------------------------------------------------------------------------
global ASM_PFX(InternalAsmThunk16)
ASM_PFX(InternalAsmThunk16):
+BITS 64
push rbp
push rbx
push rsi
@@ -300,7 +289,7 @@ ASM_PFX(InternalAsmThunk16):
mov [rcx], ebp ; save CR4 in _BackFromUserCode.SavedCr4
and ebp, ~30h ; clear PAE, PSE bits
mov esi, r8d ; esi <- 16-bit stack segment
- DB 6ah, DATA32 ; push DATA32
+ push DATA32
pop rdx ; rdx <- 32-bit data segment selector
lgdt [rcx + (_16Gdtr - _BackFromUserCode.SavedCr4)]
mov ss, edx
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-04 20:33:50 +0000