\r
m16Size DW InternalAsmThunk16 - m16Start\r
mThunk16Attr DW _ThunkAttr - m16Start\r
-m16Gdt DW _NullSegDesc - m16Start\r
+m16Gdt DW _NullSeg - m16Start\r
m16GdtrBase DW _16GdtrBase - m16Start\r
mTransition DW _EntryPoint - m16Start\r
\r
_BackFromUserCode ENDP\r
\r
_EntryPoint DD _ToUserCode - m16Start\r
- DW 8h\r
+ DW CODE16\r
_16Gdtr LABEL FWORD\r
- DW GdtEnd - _NullSegDesc - 1\r
-_16GdtrBase DQ _NullSegDesc\r
+ DW GDT_SIZE - 1\r
+_16GdtrBase DQ _NullSeg\r
_16Idtr FWORD (1 SHL 10) - 1\r
\r
;------------------------------------------------------------------------------\r
; It will be shadowed to somewhere in memory below 1MB.\r
;------------------------------------------------------------------------------\r
_ToUserCode PROC\r
- mov edi, ss\r
mov ss, edx ; set new segment selectors\r
mov ds, edx\r
mov es, edx\r
push rax\r
retf\r
@RealMode:\r
+ DB 6ah, DATA32\r
DB 2eh ; cs:\r
- mov [rsi + (SavedSs - @Base)], edi\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
retf ; transfer control to user code\r
_ToUserCode ENDP\r
\r
-_NullSegDesc DQ 0\r
-_16CsDesc 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
-_16DsDesc 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
-GdtEnd LABEL QWORD\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
InternalAsmThunk16 PROC USES rbp rbx rsi rdi\r
mov r10d, ds\r
mov r11d, es\r
+ mov r9d, ss\r
push fs\r
push gs\r
mov rsi, rcx\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
- push 10h\r
- pop rdx ; rdx <- selector for data segments\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
call fword ptr [rcx + (_EntryPoint - SavedCr4)]\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