CorebootModulePkg: Replace BSD License with BSD+Patent License

[mirror_edk2.git] / CorebootModulePkg / SecCore / Ia32 / Stack.asm

;------------------------------------------------------------------------------\r
;\r
; Copyright (c) 2013, Intel Corporation. All rights reserved.<BR>\r
; SPDX-License-Identifier: BSD-2-Clause-Patent\r
;\r
; Abstract:\r
;\r
;   Switch the stack from temporary memory to permanent memory.\r
;\r
;------------------------------------------------------------------------------\r
\r
    .586p\r
    .model  flat,C\r
    .code\r
    \r
;------------------------------------------------------------------------------\r
; VOID\r
; EFIAPI\r
; SecSwitchStack (\r
;   UINT32   TemporaryMemoryBase,\r
;   UINT32   PermenentMemoryBase\r
;   );\r
;------------------------------------------------------------------------------    \r
SecSwitchStack   PROC\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 ptr [esp]         ; copy pushed register's value to permanent memory\r
    mov   dword ptr [eax], edx    \r
    mov   edx, dword ptr [esp + 4]\r
    mov   dword ptr [eax + 4], edx    \r
    mov   edx, dword ptr [esp + 8]\r
    mov   dword ptr [eax + 8], edx    \r
    mov   edx, dword ptr [esp + 12]\r
    mov   dword ptr [eax + 12], edx    \r
    mov   edx, dword ptr [esp + 16]    ; Update this function's return address into permanent memory\r
    mov   dword ptr [eax + 16], edx    \r
    mov   esp, eax                     ; From now, esp is pointed to permanent memory\r
        \r
    ;\r
    ; Fixup the ebp point to permanent 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
SecSwitchStack   ENDP\r
\r
    END\r