diff options
Diffstat (limited to 'MdePkg/Library/BaseLib/X64')
| -rw-r--r-- | MdePkg/Library/BaseLib/X64/Thunk16.nasm | 334 |
1 files changed, 334 insertions, 0 deletions
diff --git a/MdePkg/Library/BaseLib/X64/Thunk16.nasm b/MdePkg/Library/BaseLib/X64/Thunk16.nasm new file mode 100644 index 0000000000..edd418c15a --- /dev/null +++ b/MdePkg/Library/BaseLib/X64/Thunk16.nasm @@ -0,0 +1,334 @@ +
+#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
+;
+;------------------------------------------------------------------------------
+
+global ASM_PFX(m16Size)
+global ASM_PFX(mThunk16Attr)
+global ASM_PFX(m16Gdt)
+global ASM_PFX(m16GdtrBase)
+global ASM_PFX(mTransition)
+global ASM_PFX(m16Start)
+
+struc IA32_REGS
+
+ ._EDI: resd 1
+ ._ESI: resd 1
+ ._EBP: resd 1
+ ._ESP: resd 1
+ ._EBX: resd 1
+ ._EDX: resd 1
+ ._ECX: resd 1
+ ._EAX: resd 1
+ ._DS: resw 1
+ ._ES: resw 1
+ ._FS: resw 1
+ ._GS: resw 1
+ ._EFLAGS: resq 1
+ ._EIP: resd 1
+ ._CS: resw 1
+ ._SS: resw 1
+ .size:
+
+endstruc
+
+SECTION .data
+
+;
+; These are global constant to convey information to C code.
+;
+ASM_PFX(m16Size) DW InternalAsmThunk16 - ASM_PFX(m16Start)
+ASM_PFX(mThunk16Attr) DW _ThunkAttr - ASM_PFX(m16Start)
+ASM_PFX(m16Gdt) DW _NullSeg - ASM_PFX(m16Start)
+ASM_PFX(m16GdtrBase) DW _16GdtrBase - ASM_PFX(m16Start)
+ASM_PFX(mTransition) DW _EntryPoint - ASM_PFX(m16Start)
+
+SECTION .text
+
+ASM_PFX(m16Start):
+
+SavedGdt:
+ dw 0
+ dq 0
+
+;------------------------------------------------------------------------------
+; _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:
+ ;
+ ; 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
+ pushfw ; 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 0
+ 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 + 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
+ 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 ecx, 0c0000080h
+ rdmsr
+ or ah, 1
+ wrmsr
+ DB 66h, 0b8h ; mov eax, imm32
+SavedCr0: DD 0
+ mov cr0, rax
+ DB 66h, 0eah ; jmp far cs:@64Bit
+@64Eip: DD 0
+SavedCs: DW 0
+@64BitCode:
+ db 090h
+ db 048h, 0bch ; mov rsp, imm64
+SavedSp: DQ 0 ; restore stack
+ nop
+ ret
+
+_EntryPoint:
+ DD _ToUserCode - ASM_PFX(m16Start)
+ DW CODE16
+_16Gdtr:
+ DW GDT_SIZE - 1
+_16GdtrBase:
+ DQ _NullSeg
+_16Idtr:
+ DW (1 << 10) - 1
+ DD 0
+
+;------------------------------------------------------------------------------
+; _ToUserCode() takes control in real mode before passing control to user code.
+; 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
+ mov ecx, 0c0000080h
+ mov cr0, rax ; 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 @ToUserCodeBase ; push eip
+@ToUserCodeBase:
+ pop bp ; ebp <- address of @ToUserCodeBase
+ push qword [esp + IA32_REGS.size + 2]
+ lea eax, [rsi + (@RealMode - @ToUserCodeBase)] ; 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 [rsi + (_16Idtr - @ToUserCodeBase)]
+ DB 66h, 61h ; popad
+ DB 1fh ; pop ds
+ DB 07h ; 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
+
+ALIGN 8
+
+CODE16 equ _16Code - $
+DATA16 equ _16Data - $
+DATA32 equ _32Data - $
+
+_NullSeg DQ 0
+_16Code:
+ DW -1
+ DW 0
+ DB 0
+ DB 9bh
+ DB 8fh ; 16-bit segment, 4GB limit
+ DB 0
+_16Data:
+ DW -1
+ DW 0
+ DB 0
+ DB 93h
+ DB 8fh ; 16-bit segment, 4GB limit
+ DB 0
+_32Data:
+ DW -1
+ DW 0
+ DB 0
+ DB 93h
+ DB 0cfh ; 16-bit segment, 4GB limit
+ DB 0
+
+GDT_SIZE equ $ - _NullSeg
+
+;------------------------------------------------------------------------------
+; IA32_REGISTER_SET *
+; EFIAPI
+; InternalAsmThunk16 (
+; IN IA32_REGISTER_SET *RegisterSet,
+; IN OUT VOID *Transition
+; );
+;------------------------------------------------------------------------------
+global ASM_PFX(InternalAsmThunk16)
+ASM_PFX(InternalAsmThunk16):
+ push rbp
+ push rbx
+ push rsi
+ push rdi
+
+ mov ebx, ds
+ push rbx ; Save ds segment register on the stack
+ mov ebx, es
+ push rbx ; Save es segment register on the stack
+ mov ebx, ss
+ push rbx ; Save ss segment register on the stack
+
+ push fs
+ push gs
+ mov rsi, rcx
+ movzx r8d, word [rsi + IA32_REGS._SS]
+ mov edi, [rsi + IA32_REGS._ESP]
+ lea rdi, [edi - (IA32_REGS.size + 4)]
+ imul eax, r8d, 16 ; eax <- r8d(stack segment) * 16
+ mov ebx, edi ; ebx <- stack for 16-bit code
+ push IA32_REGS.size / 4
+ add edi, eax ; edi <- linear address of 16-bit stack
+ pop rcx
+ rep movsd ; copy RegSet
+ lea ecx, [rdx + (SavedCr4 - ASM_PFX(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 - ASM_PFX(m16Start))] ; offset address
+ stosd ; [edi] <- return address of user code
+
+ sgdt [rsp + 60h] ; save GDT stack in argument space
+ movzx r10, word [rsp + 60h] ; r10 <- GDT limit
+ lea r11, [rcx + (InternalAsmThunk16 - SavedCr4) + 0xf]
+ and r11, ~0xf ; r11 <- 16-byte aligned shadowed GDT table in real mode buffer
+
+ mov [rcx + (SavedGdt - SavedCr4)], r10w ; save the limit of shadowed GDT table
+ mov [rcx + (SavedGdt - SavedCr4) + 2], r11 ; save the base address of shadowed GDT table
+
+ mov rsi, [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 [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, ~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 [rcx + (_16Gdtr - SavedCr4)]
+ mov ss, edx
+ pushfq
+ lea edx, [rdx + DATA16 - DATA32]
+ lea r8, [REL @RetFromRealMode]
+ push r8
+ mov r8d, cs
+ mov [rcx + (SavedCs - SavedCr4)], r8w
+ mov [rcx + (SavedSp - SavedCr4)], rsp
+ jmp dword far [rcx + (_EntryPoint - SavedCr4)]
+@RetFromRealMode:
+ popfq
+ lgdt [rsp + 60h] ; restore protected mode GDTR
+ lidt [rsp + 50h] ; restore protected mode IDTR
+ lea eax, [rbp - IA32_REGS.size]
+ pop gs
+ pop fs
+ pop rbx
+ mov ss, ebx
+ pop rbx
+ mov es, ebx
+ pop rbx
+ mov ds, ebx
+
+ pop rdi
+ pop rsi
+ pop rbx
+ pop rbp
+
+ ret
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