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