IntelFsp2Pkg: BaseFspSwitchStackLib Support for X64

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=3832
Add BaseFspSwitchStackLib Support for X64.

Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Ashraf Ali S <ashraf.ali.s@intel.com>
Signed-off-by: Ted Kuo <ted.kuo@intel.com>
Reviewed-by: Chasel Chiu <chasel.chiu@intel.com>

IntelFsp2Pkg/Library/BaseFspSwitchStackLib/X64/Stack.nasm

@@ -0,0 +1,72 @@
+;------------------------------------------------------------------------------
+;
+; 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
+
+%include    "PushPopRegsNasm.inc"
+
+extern ASM_PFX(SwapStack)
+
+;------------------------------------------------------------------------------
+; UINT32
+; EFIAPI
+; Pei2LoaderSwitchStack (
+;   VOID
+;   )
+;------------------------------------------------------------------------------
+global ASM_PFX(Pei2LoaderSwitchStack)
+ASM_PFX(Pei2LoaderSwitchStack):
+    xor     rax, rax
+    jmp     ASM_PFX(FspSwitchStack)
+
+;------------------------------------------------------------------------------
+; UINT32
+; EFIAPI
+; Loader2PeiSwitchStack (
+;   VOID
+;   )
+;------------------------------------------------------------------------------
+global ASM_PFX(Loader2PeiSwitchStack)
+ASM_PFX(Loader2PeiSwitchStack):
+    jmp     ASM_PFX(FspSwitchStack)
+
+;------------------------------------------------------------------------------
+; UINT32
+; EFIAPI
+; FspSwitchStack (
+;   VOID
+;   )
+;------------------------------------------------------------------------------
+global ASM_PFX(FspSwitchStack)
+ASM_PFX(FspSwitchStack):
+    ; Save current contexts
+    push    rdx     ; ApiParam2
+    push    rcx     ; ApiParam1
+    push    rax     ; FspInfoHeader
+    pushfq
+    cli
+    PUSHA_64
+    sub     rsp, 16
+    sidt    [rsp]
+
+    ; Load new stack
+    mov     rcx, rsp
+    call    ASM_PFX(SwapStack)
+    mov     rsp, rax
+
+    ; Restore previous contexts
+    lidt    [rsp]
+    add     rsp, 16
+    POPA_64
+    popfq
+    add     rsp, 24 ; FspInfoHeader + ApiParam[2]
+    ret
+