1 files changed, 72 insertions, 0 deletions
diff --git a/src/VBox/Devices/EFI/Firmware/IntelFsp2Pkg/FspSecCore/Ia32/Stack.nasm b/src/VBox/Devices/EFI/Firmware/IntelFsp2Pkg/FspSecCore/Ia32/Stack.nasm
new file mode 100644
index 00000000..a0fa9a20
--- /dev/null
+++ b/src/VBox/Devices/EFI/Firmware/IntelFsp2Pkg/FspSecCore/Ia32/Stack.nasm
@@ -0,0 +1,72 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2015 - 2019, Intel Corporation. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Abstract:
+;
+;   Switch the stack from temporary memory to permanent memory.
+;
+;------------------------------------------------------------------------------
+
+SECTION .text
+
+;------------------------------------------------------------------------------
+; VOID
+; EFIAPI
+; SecSwitchStack (
+;   UINT32   TemporaryMemoryBase,
+;   UINT32   PermenentMemoryBase
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(SecSwitchStack)
+ASM_PFX(SecSwitchStack):
+    ;
+    ; Save three register: eax, ebx, ecx
+    ;
+    push  eax
+    push  ebx
+    push  ecx
+    push  edx
+
+    ;
+    ; !!CAUTION!! this function address's is pushed into stack after
+    ; migration of whole temporary memory, so need save it to permanent
+    ; memory at first!
+    ;
+
+    mov   ebx, [esp + 20]          ; Save the first parameter
+    mov   ecx, [esp + 24]          ; Save the second parameter
+
+    ;
+    ; Save this function's return address into permanent memory at first.
+    ; Then, Fixup the esp point to permanent memory
+    ;
+    mov   eax, esp
+    sub   eax, ebx
+    add   eax, ecx
+    mov   edx, dword [esp]         ; copy pushed register's value to permanent memory
+    mov   dword [eax], edx
+    mov   edx, dword [esp + 4]
+    mov   dword [eax + 4], edx
+    mov   edx, dword [esp + 8]
+    mov   dword [eax + 8], edx
+    mov   edx, dword [esp + 12]
+    mov   dword [eax + 12], edx
+    mov   edx, dword [esp + 16]    ; Update this function's return address into permanent memory
+    mov   dword [eax + 16], edx
+    mov   esp, eax                     ; From now, esp is pointed to permanent memory
+
+    ;
+    ; Fixup the ebp point to permanent memory
+    ;
+    mov   eax, ebp
+    sub   eax, ebx
+    add   eax, ecx
+    mov   ebp, eax                ; From now, ebp is pointed to permanent memory
+
+    pop   edx
+    pop   ecx
+    pop   ebx
+    pop   eax
+    ret