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Fix the bug that if code is run above 4G, AsmDisablePaging64 will be failure. 

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@8478 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
klu2 2009-06-05 11:21:48 +00:00
parent aa4d03f7fb
commit ce4c0e31b0
1 changed files with 15 additions and 1 deletions
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16
MdePkg/Library/BaseLib/X64/DisablePaging64.asm
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@ -36,7 +36,17 @@
;------------------------------------------------------------------------------
InternalX86DisablePaging64 PROC
cli
lea r10, @F
lea rsi, @F ; rsi <- The start address of transition code
mov rdi, [rsp + 28h] ; rdi <- New stack
sub rdi, 64 ; rdi <- use 64 byte in stack to hold transition code
mov r10, rdi ; r10 <- The start address of transicition code below 4G
lea rax, mTransitionEnd ; rax <- end of transition code
sub rax, rsi ; rax <- The size of transition piece code
push rcx ; save rcx to stack
mov rcx, rax ; rcx <- The size of transition piece code
rep movsb ; copy transition code to (new stack - 64byte) below 4G
pop rcx ; restore rcx
mov esi, r8d
mov edi, r9d
mov eax, [rsp + 28h] ; eax <- New Stack
@ -44,6 +54,8 @@ InternalX86DisablePaging64 PROC
push r10
DB 48h ; prefix to composite "retq" with next "retf"
retf ; Use far return to load CS register from stack
; Start of transition code
@@:
mov esp, eax ; set up new stack
mov rax, cr0
@ -64,4 +76,6 @@ InternalX86DisablePaging64 PROC
hlt ; no one should get here
InternalX86DisablePaging64 ENDP
mTransitionEnd LABEL BYTE
END