1 files changed, 73 insertions, 0 deletions
diff --git a/IntelFsp2Pkg/FspSecCore/X64/Stack.nasm b/IntelFsp2Pkg/FspSecCore/X64/Stack.nasm
new file mode 100644
index 0000000000..0af7f54f6f
--- /dev/null
+++ b/IntelFsp2Pkg/FspSecCore/X64/Stack.nasm
@@ -0,0 +1,73 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2022, 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 (
+;   UINT64   TemporaryMemoryBase,
+;   UINT64   PermanentMemoryBase
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(SecSwitchStack)
+ASM_PFX(SecSwitchStack):
+    ;
+    ; Save four register: rax, rbx, rcx, rdx
+    ;
+    push  rax
+    push  rbx
+    push  rcx
+    push  rdx
+
+    ;
+    ; !!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   rbx, rcx                 ; Save the first parameter
+    mov   rcx, rdx                 ; Save the second parameter
+
+    ;
+    ; Save this function's return address into permanent memory at first.
+    ; Then, Fixup the esp point to permanent memory
+    ;
+    mov   rax, rsp
+    sub   rax, rbx
+    add   rax, rcx
+    mov   rdx, qword [rsp]         ; copy pushed register's value to permanent memory
+    mov   qword [rax], rdx
+    mov   rdx, qword [rsp + 8]
+    mov   qword [rax + 8], rdx
+    mov   rdx, qword [rsp + 16]
+    mov   qword [rax + 16], rdx
+    mov   rdx, qword [rsp + 24]
+    mov   qword [rax + 24], rdx
+    mov   rdx, qword [rsp + 32]    ; Update this function's return address into permanent memory
+    mov   qword [rax + 32], rdx
+    mov   rsp, rax                 ; From now, rsp is pointed to permanent memory
+
+    ;
+    ; Fixup the rbp point to permanent memory
+    ;
+    mov   rax, rbp
+    sub   rax, rbx
+    add   rax, rcx
+    mov   rbp, rax                 ; From now, rbp is pointed to permanent memory
+
+    pop   rdx
+    pop   rcx
+    pop   rbx
+    pop   rax
+    ret
+