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 2eh ; cs:\r
+ mov [rdi + (@64Eip - @Base)], ax\r
DB 66h, 0b8h ; mov eax, imm32\r
SavedCr4 DD ?\r
mov cr4, rax\r
DB 66h, 0b8h ; mov eax, imm32\r
SavedCr0 DD ?\r
mov cr0, rax\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
+ DB 66h, 0eah ; jmp far cs:@64Bit\r
+@64Eip DD ?\r
+SavedCs DW ?\r
+@64BitCode:\r
+ DB 48h, 0b8h ; mov rax, imm64\r
+SavedRip DQ ?\r
+ jmp rax ; return to caller\r
_BackFromUserCode ENDP\r
\r
_EntryPoint DD _ToUserCode - m16Start\r
wrmsr\r
mov cr4, rbp\r
mov ss, esi ; set up 16-bit stack segment\r
- xchg sp, bx ; set up 16-bit stack pointer\r
+ mov sp, bx ; set up 16-bit stack pointer\r
DB 66h\r
call @Base ; push eip\r
@Base:\r
push rax\r
retf\r
@RealMode:\r
- DB 6ah, DATA32\r
- DB 2eh ; cs:\r
- pop [rsi + (SavedSs - @Base)]\r
- DB 2eh ; cs:\r
- mov [rsi + (SavedEsp - @Base)], bx\r
DB 66h, 2eh ; CS and operand size override\r
lidt fword ptr [rsi + (_16Idtr - @Base)]\r
DB 66h, 61h ; popad\r
mov eax, edx ; eax <- transition code address\r
and edx, 0fh\r
shl eax, 12\r
- lea edx, [rdx + (_BackFromUserCode - m16Start)]\r
- mov ax, dx\r
+ lea ax, [rdx + (_BackFromUserCode - m16Start)]\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 ss, edx\r
pushfq\r
lea edx, [rdx + DATA16 - DATA32]\r
- call fword ptr [rcx + (_EntryPoint - SavedCr4)]\r
+ lea r8, @RetFromRealMode\r
+ mov [rcx + (SavedRip - SavedCr4)], 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
+ mov rsp, r8\r
popfq\r
lidt fword ptr [rsp + 38h] ; restore protected mode IDTR\r
lea eax, [rbp - sizeof (IA32_REGS)]\r