diff options
author | qhuang8 <qhuang8@6f19259b-4bc3-4df7-8a09-765794883524> | 2009-04-17 07:38:57 +0000 |
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committer | qhuang8 <qhuang8@6f19259b-4bc3-4df7-8a09-765794883524> | 2009-04-17 07:38:57 +0000 |
commit | 0fe43214e33e4276741872a783528d896d82e785 (patch) | |
tree | 538a362c0124d6be88648e62afed8aaac8830400 /MdePkg/Library/BaseLib/X64/Thunk16.asm | |
parent | 14ca06407d7fdeeb9fdaf9bfa5f9163c43776e1e (diff) | |
download | edk2-platforms-0fe43214e33e4276741872a783528d896d82e785.tar.xz |
Save segment registers on stack in case the thunk code assembly calls CF9 soft reset and the x64 registers get cleared.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@8123 6f19259b-4bc3-4df7-8a09-765794883524
Diffstat (limited to 'MdePkg/Library/BaseLib/X64/Thunk16.asm')
-rw-r--r-- | MdePkg/Library/BaseLib/X64/Thunk16.asm | 30 |
1 files changed, 20 insertions, 10 deletions
diff --git a/MdePkg/Library/BaseLib/X64/Thunk16.asm b/MdePkg/Library/BaseLib/X64/Thunk16.asm index d93af44597..cef63d98e1 100644 --- a/MdePkg/Library/BaseLib/X64/Thunk16.asm +++ b/MdePkg/Library/BaseLib/X64/Thunk16.asm @@ -140,7 +140,10 @@ SavedCr0 DD ? @64Eip DD ?
SavedCs DW ?
@64BitCode:
- mov rsp, r8 ; restore stack
+ db 090h
+ db 067h, 0bch ; mov esp, imm32
+SavedSp DD ? ; restore stack
+ nop
ret
_BackFromUserCode ENDP
@@ -230,9 +233,13 @@ GDT_SIZE = $ - _NullSeg ; );
;------------------------------------------------------------------------------
InternalAsmThunk16 PROC USES rbp rbx rsi rdi
- mov r10d, ds ; r9 ~ r11 are not accessible in 16-bit
- mov r11d, es ; so use them for saving seg registers
- mov r9d, ss
+ mov rbx, ds
+ push rbx ; Save ds segment register on the stack
+ mov rbx, es
+ push rbx ; Save es segment register on the stack
+ mov rbx, ss
+ push rbx ; Save ss segment register on the stack
+
push fs
push gs
mov rsi, rcx
@@ -252,7 +259,7 @@ InternalAsmThunk16 PROC USES rbp rbx rsi rdi lea ax, [rdx + (_BackFromUserCode - m16Start)] ; offset address
stosd ; [edi] <- return address of user code
sgdt fword ptr [rcx + (SavedGdt - SavedCr4)]
- sidt fword ptr [rsp + 38h] ; save IDT stack in argument space
+ sidt fword ptr [rsp + 50h] ; save IDT stack in argument space
mov rax, cr0
mov [rcx + (SavedCr0 - SavedCr4)], eax
and eax, 7ffffffeh ; clear PE, PG bits
@@ -270,17 +277,20 @@ InternalAsmThunk16 PROC USES rbp rbx rsi rdi push r8
mov r8d, cs
mov [rcx + (SavedCs - SavedCr4)], r8w
- mov r8, rsp
+ mov [rcx + (SavedSp - SavedCr4)], esp
jmp fword ptr [rcx + (_EntryPoint - SavedCr4)]
@RetFromRealMode:
popfq
- lidt fword ptr [rsp + 38h] ; restore protected mode IDTR
+ lidt fword ptr [rsp + 50h] ; restore protected mode IDTR
lea eax, [rbp - sizeof (IA32_REGS)]
pop gs
pop fs
- mov ss, r9d
- mov es, r11d
- mov ds, r10d
+ pop rbx
+ mov ss, rbx
+ pop rbx
+ mov es, rbx
+ pop rbx
+ mov ds, rbx
ret
InternalAsmThunk16 ENDP
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