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Added an extra GDT entry to the GDT used by thunk code. SS register will always be loaded as flat segment before switching to 16-bit mode, since SS might not be always valid for NULL selector is allowed in 64-bit mode.

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git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@1541 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
bxing 2006-09-14 16:04:47 +00:00
parent 0f008d9ad4
commit f23d790a79
1 changed files with 40 additions and 24 deletions
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64
MdePkg/Library/BaseLib/X64/Thunk16.asm
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@ -49,7 +49,7 @@ IA32_REGS ENDS
m16Size DW InternalAsmThunk16 - m16Start m16Size DW InternalAsmThunk16 - m16Start
mThunk16Attr DW _ThunkAttr - m16Start mThunk16Attr DW _ThunkAttr - m16Start
m16Gdt DW _NullSegDesc - m16Start m16Gdt DW _NullSeg - m16Start
m16GdtrBase DW _16GdtrBase - m16Start m16GdtrBase DW _16GdtrBase - m16Start
mTransition DW _EntryPoint - m16Start mTransition DW _EntryPoint - m16Start
@ -123,10 +123,10 @@ SavedEsp DD ?
_BackFromUserCode ENDP _BackFromUserCode ENDP
_EntryPoint DD _ToUserCode - m16Start _EntryPoint DD _ToUserCode - m16Start
DW 8h DW CODE16
_16Gdtr LABEL FWORD _16Gdtr LABEL FWORD
DW GdtEnd - _NullSegDesc - 1 DW GDT_SIZE - 1
_16GdtrBase DQ _NullSegDesc _16GdtrBase DQ _NullSeg
_16Idtr FWORD (1 SHL 10) - 1 _16Idtr FWORD (1 SHL 10) - 1
;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------
@ -134,7 +134,6 @@ _16Idtr FWORD (1 SHL 10) - 1
; It will be shadowed to somewhere in memory below 1MB. ; It will be shadowed to somewhere in memory below 1MB.
;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------
_ToUserCode PROC _ToUserCode PROC
mov edi, ss
mov ss, edx ; set new segment selectors mov ss, edx ; set new segment selectors
mov ds, edx mov ds, edx
mov es, edx mov es, edx
@ -158,8 +157,9 @@ _ToUserCode PROC
push rax push rax
retf retf
@RealMode: @RealMode:
DB 6ah, DATA32
DB 2eh ; cs: DB 2eh ; cs:
mov [rsi + (SavedSs - @Base)], edi pop [rsi + (SavedSs - @Base)]
DB 2eh ; cs: DB 2eh ; cs:
mov [rsi + (SavedEsp - @Base)], bx mov [rsi + (SavedEsp - @Base)], bx
DB 66h, 2eh ; CS and operand size override DB 66h, 2eh ; CS and operand size override
@ -175,22 +175,34 @@ _ToUserCode PROC
retf ; transfer control to user code retf ; transfer control to user code
_ToUserCode ENDP _ToUserCode ENDP
_NullSegDesc DQ 0 CODE16 = _16Code - $
_16CsDesc LABEL QWORD DATA16 = _16Data - $
DW -1 DATA32 = _32Data - $
DW 0
DB 0 _NullSeg DQ 0
DB 9bh _16Code LABEL QWORD
DB 8fh ; 16-bit segment, 4GB limit DW -1
DB 0 DW 0
_16DsDesc LABEL QWORD DB 0
DW -1 DB 9bh
DW 0 DB 8fh ; 16-bit segment, 4GB limit
DB 0 DB 0
DB 93h _16Data LABEL QWORD
DB 8fh ; 16-bit segment, 4GB limit DW -1
DB 0 DW 0
GdtEnd LABEL QWORD 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 * ; IA32_REGISTER_SET *
@ -203,6 +215,7 @@ GdtEnd LABEL QWORD
InternalAsmThunk16 PROC USES rbp rbx rsi rdi InternalAsmThunk16 PROC USES rbp rbx rsi rdi
mov r10d, ds mov r10d, ds
mov r11d, es mov r11d, es
mov r9d, ss
push fs push fs
push gs push gs
mov rsi, rcx mov rsi, rcx
@ -231,16 +244,19 @@ InternalAsmThunk16 PROC USES rbp rbx rsi rdi
mov [rcx], ebp ; save CR4 in SavedCr4 mov [rcx], ebp ; save CR4 in SavedCr4
and ebp, 300h ; clear all but PCE and OSFXSR bits and ebp, 300h ; clear all but PCE and OSFXSR bits
mov esi, r8d ; esi <- 16-bit stack segment mov esi, r8d ; esi <- 16-bit stack segment
push 10h DB 6ah, DATA32 ; push DATA32
pop rdx ; rdx <- selector for data segments pop rdx ; rdx <- 32-bit data segment selector
lgdt fword ptr [rcx + (_16Gdtr - SavedCr4)] lgdt fword ptr [rcx + (_16Gdtr - SavedCr4)]
mov ss, edx
pushfq pushfq
lea edx, [rdx + DATA16 - DATA32]
call fword ptr [rcx + (_EntryPoint - SavedCr4)] call fword ptr [rcx + (_EntryPoint - SavedCr4)]
popfq popfq
lidt fword ptr [rsp + 38h] ; restore protected mode IDTR lidt fword ptr [rsp + 38h] ; restore protected mode IDTR
lea eax, [rbp - sizeof (IA32_REGS)] lea eax, [rbp - sizeof (IA32_REGS)]
pop gs pop gs
pop fs pop fs
mov ss, r9d
mov es, r11d mov es, r11d
mov ds, r10d mov ds, r10d
ret ret