diff options
Diffstat (limited to 'Core/MdePkg/Library/BaseLib/X64/Thunk16.asm')
| -rw-r--r-- | Core/MdePkg/Library/BaseLib/X64/Thunk16.asm | 315 |
1 files changed, 315 insertions, 0 deletions
diff --git a/Core/MdePkg/Library/BaseLib/X64/Thunk16.asm b/Core/MdePkg/Library/BaseLib/X64/Thunk16.asm new file mode 100644 index 0000000000..e01de272d2 --- /dev/null +++ b/Core/MdePkg/Library/BaseLib/X64/Thunk16.asm @@ -0,0 +1,315 @@ +
+#include "BaseLibInternals.h"
+
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
+; This program and the accompanying materials
+; are licensed and made available under the terms and conditions of the BSD License
+; which accompanies this distribution. The full text of the license may be found at
+; http://opensource.org/licenses/bsd-license.php.
+;
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+;
+; Module Name:
+;
+; Thunk.asm
+;
+; Abstract:
+;
+; Real mode thunk
+;
+;------------------------------------------------------------------------------
+
+EXTERNDEF m16Start:BYTE
+EXTERNDEF m16Size:WORD
+EXTERNDEF mThunk16Attr:WORD
+EXTERNDEF m16Gdt:WORD
+EXTERNDEF m16GdtrBase:WORD
+EXTERNDEF mTransition:WORD
+
+IA32_REGS STRUC 4t
+_EDI DD ?
+_ESI DD ?
+_EBP DD ?
+_ESP DD ?
+_EBX DD ?
+_EDX DD ?
+_ECX DD ?
+_EAX DD ?
+_DS DW ?
+_ES DW ?
+_FS DW ?
+_GS DW ?
+_EFLAGS DQ ?
+_EIP DD ?
+_CS DW ?
+_SS DW ?
+IA32_REGS ENDS
+
+ .const
+
+m16Size DW InternalAsmThunk16 - m16Start
+mThunk16Attr DW _ThunkAttr - m16Start
+m16Gdt DW _NullSeg - m16Start
+m16GdtrBase DW _16GdtrBase - m16Start
+mTransition DW _EntryPoint - m16Start
+
+ .code
+
+m16Start LABEL BYTE
+
+SavedGdt LABEL FWORD
+ DW ?
+ DQ ?
+
+;------------------------------------------------------------------------------
+; _BackFromUserCode() takes control in real mode after 'retf' has been executed
+; by user code. It will be shadowed to somewhere in memory below 1MB.
+;------------------------------------------------------------------------------
+_BackFromUserCode PROC
+ ;
+ ; The order of saved registers on the stack matches the order they appears
+ ; 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
+@Base:
+ DB 66h
+ push 0 ; reserved high order 32 bits of EFlags
+ pushf ; pushfd actually
+ cli ; disable interrupts
+ push gs
+ push fs
+ DB 6 ; push es
+ DB 1eh ; push ds
+ DB 66h, 60h ; pushad
+ DB 66h, 0bah ; mov edx, imm32
+_ThunkAttr DD ?
+ test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15
+ jz @1
+ mov eax, 15cd2401h ; mov ax, 2401h & int 15h
+ cli ; disable interrupts
+ jnc @2
+@1:
+ test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL
+ jz @2
+ in al, 92h
+ or al, 2
+ out 92h, al ; deactivate A20M#
+@2:
+ xor ax, ax ; xor eax, eax
+ mov eax, ss ; mov ax, ss
+ lea bp, [esp + sizeof (IA32_REGS)]
+ ;
+ ; rsi in the following 2 instructions is indeed bp in 16-bit code
+ ;
+ mov word ptr (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._ESP, bp
+ DB 66h
+ mov ebx, (IA32_REGS ptr [rsi - sizeof (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
+ DB 66h, 0b8h ; mov eax, imm32
+SavedCr4 DD ?
+ mov cr4, rax
+ ;
+ ; rdi in the instruction below is indeed bx in 16-bit code
+ ;
+ DB 66h, 2eh ; 2eh is "cs:" segment override
+ lgdt fword ptr [rdi + (SavedGdt - @Base)]
+ DB 66h
+ mov ecx, 0c0000080h
+ rdmsr
+ or ah, 1
+ wrmsr
+ DB 66h, 0b8h ; mov eax, imm32
+SavedCr0 DD ?
+ mov cr0, rax
+ DB 66h, 0eah ; jmp far cs:@64Bit
+@64Eip DD ?
+SavedCs DW ?
+@64BitCode:
+ db 090h
+ db 048h, 0bch ; mov rsp, imm64
+SavedSp DQ ? ; restore stack
+ nop
+ ret
+_BackFromUserCode ENDP
+
+_EntryPoint DD _ToUserCode - m16Start
+ DW CODE16
+_16Gdtr LABEL FWORD
+ DW GDT_SIZE - 1
+_16GdtrBase DQ _NullSeg
+_16Idtr FWORD (1 SHL 10) - 1
+
+;------------------------------------------------------------------------------
+; _ToUserCode() takes control in real mode before passing control to user code.
+; It will be shadowed to somewhere in memory below 1MB.
+;------------------------------------------------------------------------------
+_ToUserCode PROC
+ mov ss, edx ; set new segment selectors
+ mov ds, edx
+ mov es, edx
+ mov fs, edx
+ mov gs, edx
+ DB 66h
+ mov ecx, 0c0000080h
+ mov cr0, rax ; real mode starts at next instruction
+ rdmsr
+ and ah, NOT 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
+@Base:
+ pop bp ; ebp <- address of @Base
+ push [esp + sizeof (IA32_REGS) + 2]
+ lea eax, [rsi + (@RealMode - @Base)] ; rsi is "bp" in 16-bit code
+ push rax
+ retf ; execution begins at next instruction
+@RealMode:
+ DB 66h, 2eh ; CS and operand size override
+ lidt fword ptr [rsi + (_16Idtr - @Base)]
+ DB 66h, 61h ; popad
+ DB 1fh ; pop ds
+ DB 07h ; pop es
+ pop fs
+ pop gs
+ popf ; 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
+_ToUserCode ENDP
+
+CODE16 = _16Code - $
+DATA16 = _16Data - $
+DATA32 = _32Data - $
+
+_NullSeg DQ 0
+_16Code LABEL QWORD
+ DW -1
+ DW 0
+ DB 0
+ DB 9bh
+ DB 8fh ; 16-bit segment, 4GB limit
+ DB 0
+_16Data LABEL QWORD
+ DW -1
+ DW 0
+ DB 0
+ DB 93h
+ DB 8fh ; 16-bit segment, 4GB limit
+ DB 0
+_32Data LABEL QWORD
+ DW -1
+ DW 0
+ DB 0
+ DB 93h
+ DB 0cfh ; 16-bit segment, 4GB limit
+ DB 0
+
+GDT_SIZE = $ - _NullSeg
+
+;------------------------------------------------------------------------------
+; IA32_REGISTER_SET *
+; EFIAPI
+; InternalAsmThunk16 (
+; IN IA32_REGISTER_SET *RegisterSet,
+; IN OUT VOID *Transition
+; );
+;------------------------------------------------------------------------------
+InternalAsmThunk16 PROC USES rbp rbx rsi rdi
+ mov rbx, ds
+ push rbx ; Save ds segment register on the stack
+ mov rbx, es
+ push rbx ; Save es segment register on the stack
+ mov rbx, ss
+ push rbx ; Save ss segment register on the stack
+
+ push fs
+ push gs
+ mov rsi, rcx
+ movzx r8d, (IA32_REGS ptr [rsi])._SS
+ mov edi, (IA32_REGS ptr [rsi])._ESP
+ lea rdi, [edi - (sizeof (IA32_REGS) + 4)]
+ imul eax, r8d, 16 ; eax <- r8d(stack segment) * 16
+ mov ebx, edi ; ebx <- stack for 16-bit code
+ push sizeof (IA32_REGS) / 4
+ add edi, eax ; edi <- linear address of 16-bit stack
+ pop rcx
+ rep movsd ; copy RegSet
+ lea ecx, [rdx + (SavedCr4 - m16Start)]
+ mov eax, edx ; eax <- transition code address
+ and edx, 0fh
+ shl eax, 12 ; segment address in high order 16 bits
+ lea ax, [rdx + (_BackFromUserCode - m16Start)] ; offset address
+ stosd ; [edi] <- return address of user code
+
+ sgdt fword ptr [rsp + 60h] ; save GDT stack in argument space
+ movzx r10, word ptr [rsp + 60h] ; r10 <- GDT limit
+ lea r11, [rcx + (InternalAsmThunk16 - SavedCr4) + 0xf]
+ and r11, 0xfffffff0 ; r11 <- 16-byte aligned shadowed GDT table in real mode buffer
+
+ mov word ptr [rcx + (SavedGdt - SavedCr4)], r10w ; save the limit of shadowed GDT table
+ mov qword ptr [rcx + (SavedGdt - SavedCr4) + 2], r11 ; save the base address of shadowed GDT table
+
+ mov rsi, qword ptr [rsp + 62h] ; rsi <- the original GDT base address
+ xchg rcx, r10 ; save rcx to r10 and initialize rcx to be the limit of GDT table
+ inc rcx ; rcx <- the size of memory to copy
+ xchg rdi, r11 ; save rdi to r11 and initialize rdi to the base address of shadowed GDT table
+ rep movsb ; perform memory copy to shadow GDT table
+ mov rcx, r10 ; restore the orignal rcx before memory copy
+ mov rdi, r11 ; restore the original rdi before memory copy
+
+ sidt fword ptr [rsp + 50h] ; save IDT stack in argument space
+ mov rax, cr0
+ mov [rcx + (SavedCr0 - SavedCr4)], eax
+ and eax, 7ffffffeh ; clear PE, PG bits
+ mov rbp, cr4
+ mov [rcx], ebp ; save CR4 in SavedCr4
+ and ebp, NOT 30h ; clear PAE, PSE bits
+ mov esi, r8d ; esi <- 16-bit stack segment
+ DB 6ah, DATA32 ; push DATA32
+ pop rdx ; rdx <- 32-bit data segment selector
+ lgdt fword ptr [rcx + (_16Gdtr - SavedCr4)]
+ mov ss, edx
+ pushfq
+ lea edx, [rdx + DATA16 - DATA32]
+ lea r8, @RetFromRealMode
+ push r8
+ mov r8d, cs
+ mov [rcx + (SavedCs - SavedCr4)], r8w
+ mov [rcx + (SavedSp - SavedCr4)], rsp
+ jmp fword ptr [rcx + (_EntryPoint - SavedCr4)]
+@RetFromRealMode:
+ popfq
+ lgdt fword ptr [rsp + 60h] ; restore protected mode GDTR
+ lidt fword ptr [rsp + 50h] ; restore protected mode IDTR
+ lea eax, [rbp - sizeof (IA32_REGS)]
+ pop gs
+ pop fs
+ pop rbx
+ mov ss, rbx
+ pop rbx
+ mov es, rbx
+ pop rbx
+ mov ds, rbx
+ ret
+InternalAsmThunk16 ENDP
+
+ END
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