1 files changed, 26 insertions, 14 deletions
diff --git a/IntelFsp2Pkg/FspSecCore/X64/FspApiEntryT.nasm b/IntelFsp2Pkg/FspSecCore/X64/FspApiEntryT.nasm
index 7dd89c5..cdebe90 100644
--- a/IntelFsp2Pkg/FspSecCore/X64/FspApiEntryT.nasm
+++ b/IntelFsp2Pkg/FspSecCore/X64/FspApiEntryT.nasm
@@ -21,7 +21,7 @@ extern   ASM_PFX(PcdGet32 (PcdFspReservedBufferSize))
 ; Following functions will be provided in PlatformSecLib
 ;
 extern ASM_PFX(AsmGetFspBaseAddress)
-extern ASM_PFX(AsmGetFspInfoHeader)
+extern ASM_PFX(AsmGetFspInfoHeaderNoStack)
 ;extern ASM_PFX(LoadMicrocode)    ; @todo: needs a weak implementation
 extern ASM_PFX(SecPlatformInit)   ; @todo: needs a weak implementation
 extern ASM_PFX(SecCarInit)
@@ -87,6 +87,14 @@ struc LoadMicrocodeParamsFsp24
     .size:
 endstruc
 
+%macro CALL_RDI  1
+
+  mov     rdi,  %%ReturnAddress
+  jmp     %1
+%%ReturnAddress:
+
+%endmacro
+
 ;
 ; @todo: The strong/weak implementation does not work.
 ;        This needs to be reviewed later.
@@ -116,8 +124,7 @@ ASM_PFX(LoadMicrocodeDefault):
    ; Inputs:
    ;   rcx -> LoadMicrocodeParams pointer
    ; Register Usage:
-   ;   rsp  Preserved
-   ;   All others destroyed
+   ;   All are destroyed
    ; Assumptions:
    ;   No memory available, stack is hard-coded and used for return address
    ;   Executed by SBSP and NBSP
@@ -420,10 +427,6 @@ ASM_PFX(TempRamInitApi):
   ENABLE_SSE
   ENABLE_AVX
   ;
-  ; Save Input Parameter in YMM10
-  ;
-  SAVE_RCX
-  ;
   ; Save RBP, RBX, RSI, RDI and RSP in YMM7, YMM8 and YMM6
   ;
   SAVE_REGS
@@ -434,6 +437,22 @@ ASM_PFX(TempRamInitApi):
   SAVE_BFV  rbp
 
   ;
+  ; Save Input Parameter in YMM10
+  ;
+  cmp       rcx, 0
+  jnz       ParamValid
+
+  ;
+  ; Fall back to default UPD
+  ;
+  CALL_RDI  ASM_PFX(AsmGetFspInfoHeaderNoStack)
+  xor       rcx, rcx
+  mov       ecx,  DWORD [rax + 01Ch]      ; Read FsptImageBaseAddress
+  add       ecx,  DWORD [rax + 024h]      ; Get Cfg Region base address = FsptImageBaseAddress + CfgRegionOffset
+ParamValid:
+  SAVE_RCX
+
+  ;
   ; Save timestamp into YMM6
   ;
   rdtsc
@@ -442,13 +461,6 @@ ASM_PFX(TempRamInitApi):
   SAVE_TS   rax
 
   ;
-  ; Check Parameter
-  ;
-  cmp       rcx, 0
-  mov       rcx, 08000000000000002h
-  jz        TempRamInitExit
-
-  ;
   ; Sec Platform Init
   ;
   CALL_YMM  ASM_PFX(SecPlatformInit)