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-rw-r--r--MdePkg/Library/BaseLib/X64/DisablePaging64.S17
1 files changed, 14 insertions, 3 deletions
diff --git a/MdePkg/Library/BaseLib/X64/DisablePaging64.S b/MdePkg/Library/BaseLib/X64/DisablePaging64.S
index 038af71..242c0a0 100644
--- a/MdePkg/Library/BaseLib/X64/DisablePaging64.S
+++ b/MdePkg/Library/BaseLib/X64/DisablePaging64.S
@@ -37,8 +37,19 @@
ASM_GLOBAL ASM_PFX(InternalX86DisablePaging64)
ASM_PFX(InternalX86DisablePaging64):
- cli
- lea L1(%rip), %r10
+ cli
+ lea L1(%rip), %rsi # rsi <- The start address of transition code
+ mov 0x28(%rsp), %rdi # rdi <- New stack
+ sub $64, %rdi # rdi <- use 64 byte in stack to hold transition code
+ mov %rdi, %r10 # r10 <- The start address of transicition code below 4G
+ lea _mTransitionEnd(%rip), %rax # rax <- end of transition code
+ sub %rsi, %rax # rax <- The size of transition piece code
+ push %rcx # save rcx to stack
+ mov %rax, %rcx # rcx <- The size of transition piece code
+ rep
+ movsb # copy transition code to (new stack - 64byte) below 4G
+ pop %rcx # restore rcx
+
mov %r8d, %esi
mov %r9d, %edi
mov 0x28(%rsp), %eax # eax <- New Stack
@@ -64,4 +75,4 @@ L1:
push %rsi # push Context1
callq *%rbx # transfer control to EntryPoint
jmp . # no one should get here
-
+ _mTransitionEnd :