diff options
| author | qhuang8 <qhuang8@6f19259b-4bc3-4df7-8a09-765794883524> | 2009-04-17 07:38:57 +0000 |
|---|---|---|
| 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.S | |
| 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.S')
| -rw-r--r-- | MdePkg/Library/BaseLib/X64/Thunk16.S | 34 |
1 files changed, 22 insertions, 12 deletions
diff --git a/MdePkg/Library/BaseLib/X64/Thunk16.S b/MdePkg/Library/BaseLib/X64/Thunk16.S index b829685b43..f9770b258c 100644 --- a/MdePkg/Library/BaseLib/X64/Thunk16.S +++ b/MdePkg/Library/BaseLib/X64/Thunk16.S @@ -136,10 +136,13 @@ SavedCr4: .space 4 SavedCr0: .space 4
movq %rax, %cr0
.byte 0x66,0xea # jmp far cs:L_64Bit
-L_64Eip: .space 4
+L_64Eip: .space 4
SavedCs: .space 2
L_64BitCode:
- movq %r8, %rsp
+ .byte 0x90
+ .byte 0x67,0xbc # mov esp, imm32
+SavedSp: .space 4 # restore stack
+ nop
ret
_EntryPoint: .long ASM_PFX(ToUserCode) - ASM_PFX(m16Start)
@@ -227,7 +230,6 @@ ASM_PFX(_32Data): # IN OUT VOID *Transition
# );
#------------------------------------------------------------------------------
-# MISMATCH: "InternalAsmThunk16 PROC USES rbp rbx rsi rdi"
.globl ASM_PFX(InternalAsmThunk16)
ASM_PFX(InternalAsmThunk16):
@@ -236,9 +238,13 @@ ASM_PFX(InternalAsmThunk16): pushq %rsi
pushq %rdi
- movl %ds, %r10d # r9 ~ r11 are not accessible in 16-bit
- movl %es, %r11d # so use them for saving seg registers
- movl %ss, %r9d
+ movq %ds, %rbx
+ pushq %rbx # Save ds segment register on the stack
+ movq %es, %rbx
+ pushq %rbx # Save es segment register on the stack
+ movq %ss, %rbx
+ pushq %rbx # Save ss segment register on the stack
+
.byte 0x0f, 0xa0 #push fs
.byte 0x0f, 0xa8 #push gs
movq %rcx, %rsi
@@ -259,7 +265,7 @@ ASM_PFX(InternalAsmThunk16): lea (_BackFromUserCode - ASM_PFX(m16Start))(%rdx), %ax
stosl # [edi] <- return address of user code
sgdt (SavedGdt - SavedCr4)(%rcx)
- sidt 0x38(%rsp)
+ sidt 0x50(%rsp)
movq %cr0, %rax
movl %eax, (SavedCr0 - SavedCr4)(%rcx)
andl $0x7ffffffe,%eax # clear PE, PG bits
@@ -277,18 +283,22 @@ ASM_PFX(InternalAsmThunk16): pushq %r8
movl %cs, %r8d
movw %r8w, (SavedCs - SavedCr4)(%rcx)
- movq %rsp, %r8
+ movl %esp, (SavedSp - SavedCr4)(%rcx)
.byte 0xff, 0x69 # jmp (_EntryPoint - SavedCr4)(%rcx)
.byte _EntryPoint - SavedCr4
L_RetFromRealMode:
popfq
- lidt 0x38(%rsp)
+ lidt 0x50(%rsp)
lea -IA32_REGS_SIZE(%rbp), %eax
.byte 0x0f, 0xa9 # pop gs
.byte 0x0f, 0xa1 # pop fs
- movl %r9d, %ss
- movl %r11d, %es
- movl %r10d, %ds
+
+ popq %rbx + movq %rbx, %ss + popq %rbx + movq %rbx, %es + popq %rbx + movq %rbx, %ds popq %rdi
popq %rsi
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