+++ /dev/null
-;------------------------------------------------------------------------------\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
-EXTERNDEF m16Start:BYTE\r
-EXTERNDEF m16Size:WORD\r
-EXTERNDEF mThunk16Attr:WORD\r
-EXTERNDEF m16Gdt:WORD\r
-EXTERNDEF m16GdtrBase:WORD\r
-EXTERNDEF mTransition:WORD\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 DQ ?\r
-_EIP DD ?\r
-_CS DW ?\r
-_SS DW ?\r
-IA32_REGS ENDS\r
-\r
- .const\r
-\r
-m16Size DW InternalAsmThunk16 - m16Start\r
-mThunk16Attr DW _ThunkAttr - m16Start\r
-m16Gdt DW _NullSeg - 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
- DQ ?\r
-\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
- ;\r
- ; The order of saved registers on the stack matches the order they appears\r
- ; in IA32_REGS structure. This facilitates wrapper function to extract them\r
- ; into that structure.\r
- ;\r
- ; Some instructions for manipulation of segment registers have to be written\r
- ; in opcode since 64-bit MASM prevents accesses to those registers.\r
- ;\r
- DB 16h ; push ss\r
- DB 0eh ; push cs\r
- DB 66h\r
- call @Base ; push eip\r
-@Base:\r
- DB 66h\r
- push 0 ; reserved high order 32 bits of EFlags\r
- pushf ; pushfd actually\r
- cli ; disable interrupts\r
- push gs\r
- push fs\r
- DB 6 ; push es\r
- DB 1eh ; push ds\r
- DB 66h, 60h ; pushad\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
- lea bp, [esp + sizeof (IA32_REGS)]\r
- ;\r
- ; rsi in the following 2 instructions is indeed bp in 16-bit code\r
- ;\r
- mov word ptr (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._ESP, bp\r
- DB 66h\r
- mov ebx, (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._EIP\r
- shl ax, 4 ; shl eax, 4\r
- add bp, ax ; add ebp, eax\r
- mov ax, cs\r
- shl ax, 4\r
- lea ax, [eax + ebx + (@64BitCode - @Base)]\r
- DB 66h, 2eh, 89h, 87h ; mov cs:[bx + (@64Eip - @Base)], eax\r
- DW @64Eip - @Base\r
- DB 66h, 0b8h ; mov eax, imm32\r
-SavedCr4 DD ?\r
- mov cr4, rax\r
- ;\r
- ; rdi in the instruction below is indeed bx in 16-bit code\r
- ;\r
- DB 66h, 2eh ; 2eh is "cs:" segment override\r
- lgdt fword ptr [rdi + (SavedGdt - @Base)]\r
- DB 66h\r
- mov ecx, 0c0000080h\r
- rdmsr\r
- or ah, 1\r
- wrmsr\r
- DB 66h, 0b8h ; mov eax, imm32\r
-SavedCr0 DD ?\r
- mov cr0, rax\r
- DB 66h, 0eah ; jmp far cs:@64Bit\r
-@64Eip DD ?\r
-SavedCs DW ?\r
-@64BitCode:\r
- mov rsp, r8 ; restore stack\r
- ret\r
-_BackFromUserCode ENDP\r
-\r
-_EntryPoint DD _ToUserCode - m16Start\r
- DW CODE16\r
-_16Gdtr LABEL FWORD\r
- DW GDT_SIZE - 1\r
-_16GdtrBase DQ _NullSeg\r
-_16Idtr FWORD (1 SHL 10) - 1\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 ss, edx ; set new segment selectors\r
- mov ds, edx\r
- mov es, edx\r
- mov fs, edx\r
- mov gs, edx\r
- DB 66h\r
- mov ecx, 0c0000080h\r
- mov cr0, rax ; real mode starts at next instruction\r
- rdmsr\r
- and ah, NOT 1\r
- wrmsr\r
- mov cr4, rbp\r
- mov ss, esi ; set up 16-bit stack segment\r
- mov sp, bx ; set up 16-bit stack pointer\r
- DB 66h ; make the following call 32-bit\r
- call @Base ; push eip\r
-@Base:\r
- pop bp ; ebp <- address of @Base\r
- push [esp + sizeof (IA32_REGS) + 2]\r
- lea eax, [rsi + (@RealMode - @Base)] ; rsi is "bp" in 16-bit code\r
- push rax\r
- retf ; execution begins at next instruction\r
-@RealMode:\r
- DB 66h, 2eh ; CS and operand size override\r
- lidt fword ptr [rsi + (_16Idtr - @Base)]\r
- DB 66h, 61h ; popad\r
- DB 1fh ; pop ds\r
- DB 07h ; pop es\r
- pop fs\r
- pop gs\r
- popf ; popfd\r
- lea sp, [esp + 4] ; skip high order 32 bits of EFlags\r
- DB 66h ; make the following retf 32-bit\r
- retf ; transfer control to user code\r
-_ToUserCode ENDP\r
-\r
-CODE16 = _16Code - $\r
-DATA16 = _16Data - $\r
-DATA32 = _32Data - $\r
-\r
-_NullSeg DQ 0\r
-_16Code 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
-_16Data 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
-_32Data LABEL QWORD\r
- DW -1\r
- DW 0\r
- DB 0\r
- DB 93h\r
- DB 0cfh ; 16-bit segment, 4GB limit\r
- DB 0\r
-\r
-GDT_SIZE = $ - _NullSeg\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 rbp rbx rsi rdi\r
- mov r10d, ds ; r9 ~ r11 are not accessible in 16-bit\r
- mov r11d, es ; so use them for saving seg registers\r
- mov r9d, ss\r
- push fs\r
- push gs\r
- mov rsi, rcx\r
- movzx r8d, (IA32_REGS ptr [rsi])._SS\r
- mov edi, (IA32_REGS ptr [rsi])._ESP\r
- lea rdi, [edi - (sizeof (IA32_REGS) + 4)]\r
- imul eax, r8d, 16 ; eax <- r8d(stack segment) * 16\r
- mov ebx, edi ; ebx <- stack for 16-bit code\r
- push sizeof (IA32_REGS) / 4\r
- add edi, eax ; edi <- linear address of 16-bit stack\r
- pop rcx\r
- rep movsd ; copy RegSet\r
- lea ecx, [rdx + (SavedCr4 - m16Start)]\r
- mov eax, edx ; eax <- transition code address\r
- and edx, 0fh\r
- shl eax, 12 ; segment address in high order 16 bits\r
- lea ax, [rdx + (_BackFromUserCode - m16Start)] ; offset address\r
- stosd ; [edi] <- return address of user code\r
- sgdt fword ptr [rcx + (SavedGdt - SavedCr4)]\r
- sidt fword ptr [rsp + 38h] ; save IDT stack in argument space\r
- mov rax, cr0\r
- mov [rcx + (SavedCr0 - SavedCr4)], eax\r
- and eax, 7ffffffeh ; clear PE, PG bits\r
- mov rbp, cr4\r
- mov [rcx], ebp ; save CR4 in SavedCr4\r
- and ebp, 300h ; clear all but PCE and OSFXSR bits\r
- mov esi, r8d ; esi <- 16-bit stack segment\r
- DB 6ah, DATA32 ; push DATA32\r
- pop rdx ; rdx <- 32-bit data segment selector\r
- lgdt fword ptr [rcx + (_16Gdtr - SavedCr4)]\r
- mov ss, edx\r
- pushfq\r
- lea edx, [rdx + DATA16 - DATA32]\r
- lea r8, @RetFromRealMode\r
- push r8\r
- mov r8d, cs\r
- mov [rcx + (SavedCs - SavedCr4)], r8w\r
- mov r8, rsp\r
- jmp fword ptr [rcx + (_EntryPoint - SavedCr4)]\r
-@RetFromRealMode:\r
- popfq\r
- lidt fword ptr [rsp + 38h] ; restore protected mode IDTR\r
- lea eax, [rbp - sizeof (IA32_REGS)]\r
- pop gs\r
- pop fs\r
- mov ss, r9d\r
- mov es, r11d\r
- mov ds, r10d\r
- ret\r
-InternalAsmThunk16 ENDP\r
-\r
- END\r
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