sravan/system76-edk2
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1. Added comments to ASM files

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2. Fixed a bug in 64-bit AsmDisablePaging64(), which may cause a #GP exception.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@2206 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
bxing
2007-01-10 06:57:04 +00:00
parent 741fb36417
commit a9a812a0ed
45 changed files with 184 additions and 77 deletions
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18
MdePkg/Library/BaseLib/Ia32/Thunk16.asm
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@@ -75,6 +75,11 @@ SavedGdt LABEL FWORD
; by user code. It will be shadowed to somewhere in memory below 1MB.
;------------------------------------------------------------------------------
_BackFromUserCode PROC
;
; The order of saved registers on the stack matches the order they appears
; in IA32_REGS structure. This facilitates wrapper function to extract them
; into that structure.
;
push ss
push cs
DB 66h
@@ -104,6 +109,11 @@ _ThunkAttr DD ?
mov eax, ss
DB 67h
lea bp, [esp + sizeof (IA32_REGS)]
;
; esi's in the following 2 instructions are indeed bp in 16-bit code. Fact
; is "esi" in 32-bit addressing mode has the same encoding of "bp" in 16-
; bit addressing mode.
;
mov word ptr (IA32_REGS ptr [esi - sizeof (IA32_REGS)])._ESP, bp
mov ebx, (IA32_REGS ptr [esi - sizeof (IA32_REGS)])._EIP
shl ax, 4 ; shl eax, 4
@@ -167,7 +177,7 @@ _ToUserCode PROC
pop fs
pop gs
popf ; popfd
DB 66h
DB 66h ; Use 32-bit addressing for "retf" below
retf ; transfer control to user code
_ToUserCode ENDP
@@ -197,7 +207,7 @@ GdtEnd LABEL QWORD
; );
;------------------------------------------------------------------------------
InternalAsmThunk16 PROC USES ebp ebx esi edi ds es fs gs
mov esi, [esp + 36] ; esi <- RegSet
mov esi, [esp + 36] ; esi <- RegSet, the 1st parameter
movzx edx, (IA32_REGS ptr [esi])._SS
mov edi, (IA32_REGS ptr [esi])._ESP
add edi, - (sizeof (IA32_REGS) + 4) ; reserve stack space
@@ -227,11 +237,11 @@ InternalAsmThunk16 PROC USES ebp ebx esi edi ds es fs gs
push 10h
pop ecx ; ecx <- selector for data segments
lgdt fword ptr [edx + (_16Gdtr - SavedCr0)]
pushfd
pushfd ; Save df/if indeed
call fword ptr [edx + (_EntryPoint - SavedCr0)]
popfd
lidt fword ptr [esp + 36] ; restore protected mode IDTR
lea eax, [ebp - sizeof (IA32_REGS)]
lea eax, [ebp - sizeof (IA32_REGS)] ; eax <- the address of IA32_REGS
ret
InternalAsmThunk16 ENDP