--- /dev/null
+;------------------------------------------------------------------------------\r
+;\r
+; Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>\r
+; This program and the accompanying materials\r
+; are licensed and made available under the terms and conditions of the BSD License\r
+; which accompanies this distribution. The full text of the license may be found at\r
+; http://opensource.org/licenses/bsd-license.php.\r
+;\r
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
+;\r
+; Abstract:\r
+;\r
+; Switch the stack from temporary memory to permanent memory.\r
+;\r
+;------------------------------------------------------------------------------\r
+\r
+SECTION .text\r
+\r
+;------------------------------------------------------------------------------\r
+; VOID\r
+; EFIAPI\r
+; SecSwitchStack (\r
+; UINT32 TemporaryMemoryBase,\r
+; UINT32 PermenentMemoryBase\r
+; );\r
+;------------------------------------------------------------------------------\r
+global ASM_PFX(SecSwitchStack)\r
+ASM_PFX(SecSwitchStack):\r
+ ;\r
+ ; Save three register: eax, ebx, ecx\r
+ ;\r
+ push eax\r
+ push ebx\r
+ push ecx\r
+ push edx\r
+\r
+ ;\r
+ ; !!CAUTION!! this function address's is pushed into stack after\r
+ ; migration of whole temporary memory, so need save it to permanent\r
+ ; memory at first!\r
+ ;\r
+\r
+ mov ebx, [esp + 20] ; Save the first parameter\r
+ mov ecx, [esp + 24] ; Save the second parameter\r
+\r
+ ;\r
+ ; Save this function's return address into permanent memory at first.\r
+ ; Then, Fixup the esp point to permanent memory\r
+ ;\r
+ mov eax, esp\r
+ sub eax, ebx\r
+ add eax, ecx\r
+ mov edx, dword [esp] ; copy pushed register's value to permanent memory\r
+ mov dword [eax], edx\r
+ mov edx, dword [esp + 4]\r
+ mov dword [eax + 4], edx\r
+ mov edx, dword [esp + 8]\r
+ mov dword [eax + 8], edx\r
+ mov edx, dword [esp + 12]\r
+ mov dword [eax + 12], edx\r
+ mov edx, dword [esp + 16] ; Update this function's return address into permanent memory\r
+ mov dword [eax + 16], edx\r
+ mov esp, eax ; From now, esp is pointed to permanent memory\r
+\r
+ ;\r
+ ; Fixup the ebp point to permenent memory\r
+ ;\r
+ mov eax, ebp\r
+ sub eax, ebx\r
+ add eax, ecx\r
+ mov ebp, eax ; From now, ebp is pointed to permanent memory\r
+\r
+ pop edx\r
+ pop ecx\r
+ pop ebx\r
+ pop eax\r
+ ret\r