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MdePkg BaseLib NASM Thunk16: Remove remaining 'DB' code

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Convert remaining 'DB' code to assembly code by:
* Move instruction immediate data labels to end of instruction
* Use strict keyword to make sure immediate data size is not optimized

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16024 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Jordan Justen
2014-09-01 17:23:57 +00:00
committed by jljusten
parent f6888eea46
commit 7458df400c
2 changed files with 46 additions and 49 deletions
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47
MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
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@@ -59,7 +59,7 @@ SECTION .data
; These are global constant to convey information to C code.
;
ASM_PFX(m16Size) DW InternalAsmThunk16 - ASM_PFX(m16Start)
ASM_PFX(mThunk16Attr) DW _BackFromUserCode.ThunkAttr - ASM_PFX(m16Start)
ASM_PFX(mThunk16Attr) DW _BackFromUserCode.ThunkAttrEnd - 4 - ASM_PFX(m16Start)
ASM_PFX(m16Gdt) DW _NullSegDesc - ASM_PFX(m16Start)
ASM_PFX(m16GdtrBase) DW _16GdtrBase - ASM_PFX(m16Start)
ASM_PFX(mTransition) DW _EntryPoint - ASM_PFX(m16Start)
@@ -94,8 +94,8 @@ o32 call dword .Base ; push eip
push es
push ds
pushad
DB 66h, 0bah ; mov edx, imm32
.ThunkAttr: dd 0
mov edx, strict dword 0
.ThunkAttrEnd:
test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15
jz .1
mov ax, 2401h
@@ -116,18 +116,18 @@ o32 call dword .Base ; push eip
mov bx, [bp - IA32_REGS.size + IA32_REGS._EIP]
shl eax, 4 ; shl eax, 4
add ebp, eax ; add ebp, eax
DB 66h, 0b8h ; mov eax, imm32
.SavedCr4: DD 0
mov eax, strict dword 0
.SavedCr4End:
mov cr4, eax
o32 lgdt [cs:bx + (SavedGdt - .Base)]
DB 66h, 0b8h ; mov eax, imm32
.SavedCr0: DD 0
mov eax, strict dword 0
.SavedCr0End:
mov cr0, eax
DB 0b8h ; mov ax, imm16
.SavedSs DW 0
mov ax, strict word 0
.SavedSsEnd:
mov ss, eax
DB 66h, 0bch ; mov esp, imm32
.SavedEsp DD 0
mov esp, strict dword 0
.SavedEspEnd:
o32 retf ; return to protected mode
_EntryPoint:
@@ -155,15 +155,14 @@ BITS 16
mov gs, cx
mov cr0, eax ; real mode starts at next instruction
; which (per SDM) *must* be a far JMP.
DB 0eah
.RealAddr: DW 0, 0
jmp 0:strict word 0
.RealAddrEnd:
mov cr4, ebp
mov ss, si ; set up 16-bit stack segment
xchg esp, ebx ; set up 16-bit stack pointer
mov bp, [esp + IA32_REGS.size]
mov [cs:bp + (_BackFromUserCode.SavedSs - _BackFromUserCode)], dx
mov [cs:bp + (_BackFromUserCode.SavedEsp - _BackFromUserCode)], ebx
mov [cs:bp + (_BackFromUserCode.SavedSsEnd - 2 - _BackFromUserCode)], dx
mov [cs:bp + (_BackFromUserCode.SavedEspEnd - 4 - _BackFromUserCode)], ebx
lidt [cs:bp + (_16Idtr - _BackFromUserCode)]
popad
@@ -224,28 +223,28 @@ BITS 32
rep movsd ; copy RegSet
mov eax, [esp + 40] ; eax <- address of transition code
mov esi, edx ; esi <- 16-bit stack segment
lea edx, [eax + (_BackFromUserCode.SavedCr0 - ASM_PFX(m16Start))]
lea edx, [eax + (_BackFromUserCode.SavedCr0End - ASM_PFX(m16Start))]
mov ecx, eax
and ecx, 0fh
shl eax, 12
lea ecx, [ecx + (_BackFromUserCode - ASM_PFX(m16Start))]
mov ax, cx
stosd ; [edi] <- return address of user code
add eax, _ToUserCode.RealAddr + 4 - _BackFromUserCode
mov [edx + (_ToUserCode.RealAddr - _BackFromUserCode.SavedCr0)], eax
sgdt [edx + (SavedGdt - _BackFromUserCode.SavedCr0)]
add eax, _ToUserCode.RealAddrEnd - _BackFromUserCode
mov [edx + (_ToUserCode.RealAddrEnd - 4 - _BackFromUserCode.SavedCr0End)], eax
sgdt [edx + (SavedGdt - _BackFromUserCode.SavedCr0End)]
sidt [esp + 36] ; save IDT stack in argument space
mov eax, cr0
mov [edx], eax ; save CR0 in _BackFromUserCode.SavedCr0
mov [edx - 4], eax ; save CR0 in _BackFromUserCode.SavedCr0End - 4
and eax, 7ffffffeh ; clear PE, PG bits
mov ebp, cr4
mov [edx + (_BackFromUserCode.SavedCr4 - _BackFromUserCode.SavedCr0)], ebp
mov [edx + (_BackFromUserCode.SavedCr4End - 4 - _BackFromUserCode.SavedCr0End)], ebp
and ebp, ~30h ; clear PAE, PSE bits
push 10h
pop ecx ; ecx <- selector for data segments
lgdt [edx + (_16Gdtr - _BackFromUserCode.SavedCr0)]
lgdt [edx + (_16Gdtr - _BackFromUserCode.SavedCr0End)]
pushfd ; Save df/if indeed
call dword far [edx + (_EntryPoint - _BackFromUserCode.SavedCr0)]
call dword far [edx + (_EntryPoint - _BackFromUserCode.SavedCr0End)]
popfd
lidt [esp + 36] ; restore protected mode IDTR
lea eax, [ebp - IA32_REGS.size] ; eax <- the address of IA32_REGS