[PATCH] IntelFsp2Pkg: FSP can utilize bootloader stack

["Chasel, Chiu" <chasel.chiu@intel.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1485

Current FSP utilizes pre-allocated temporary memory from
boot loader for both heap and stack. To reduce overall
temporary memory usage FSP may share the same stack with
boot loader and only needs a smaller memory for heap,
no separate memory required for stack.
Setting PcdFspHeapSizePercentage to 0 to enable FSP sharing
stack with boot loader, in this case boot loader stack
has to be large enough for FSP to use. Default is 50
(half memory heap and half memory stack) for backward
compatible with original model.

Test: Verified on internal platform and booting successfully
      with both modes.

Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Chasel Chiu <chasel.chiu@intel.com>
---
 IntelFsp2Pkg/FspSecCore/SecMain.c              | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------------
 IntelFsp2Pkg/FspSecCore/FspSecCoreM.inf        |  3 ++-
 IntelFsp2Pkg/FspSecCore/Ia32/FspApiEntryM.nasm | 52 ++++++++++++++++++++++++++++++++++++++++++++++------
 IntelFsp2Pkg/FspSecCore/Ia32/ReadEsp.nasm      | 28 ++++++++++++++++++++++++++++
 IntelFsp2Pkg/IntelFsp2Pkg.dec                  |  4 ++++
 5 files changed, 154 insertions(+), 19 deletions(-)

diff --git a/IntelFsp2Pkg/FspSecCore/SecMain.c b/IntelFsp2Pkg/FspSecCore/SecMain.c
index 70460a3c8b..b0b5dda711 100644
--- a/IntelFsp2Pkg/FspSecCore/SecMain.c
+++ b/IntelFsp2Pkg/FspSecCore/SecMain.c
@@ -1,6 +1,6 @@
 /** @file
 
-  Copyright (c) 2014 - 2018, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2014 - 2019, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -38,6 +38,19 @@ UINT64  mIdtEntryTemplate = 0xffff8e000008ffe4ULL;
 
 /**
 
+  Return value of esp
+
+  @return  value of esp
+
+**/
+UINT32
+EFIAPI
+AsmReadEsp (
+  VOID
+  );
+
+/**
+
   Entry point to the C language phase of SEC. After the SEC assembly
   code has initialized some temporary memory and set up the stack,
   the control is transferred to this function.
@@ -83,7 +96,26 @@ SecStartup (
   //
   InitializeFloatingPointUnits ();
 
+  //
+  // Scenario 1 memory map when running on bootloader stack
+  //
+  // |-------------------|---->
+  // |Idt Table          |
+  // |-------------------|
+  // |PeiService Pointer |
+  // |-------------------|
+  // |                   |
+  // |                   |
+  // |      Heap         |
+  // |                   |
+  // |                   |
+  // |-------------------|---->  TempRamBase
+  // |Bootloader stack   |
+  // |-------------------|
 
+  //
+  // Scenario 2 memory map when running FSP on a separate stack
+  //
   // |-------------------|---->
   // |Idt Table          |
   // |-------------------|
@@ -135,11 +167,19 @@ SecStartup (
   SecCoreData.BootFirmwareVolumeSize = (UINT32)((EFI_FIRMWARE_VOLUME_HEADER *)BootFirmwareVolume)->FvLength;
 
   SecCoreData.TemporaryRamBase       = (VOID*)(UINTN) TempRamBase;
-  SecCoreData.TemporaryRamSize       = SizeOfRam;
-  SecCoreData.PeiTemporaryRamBase    = SecCoreData.TemporaryRamBase;
-  SecCoreData.PeiTemporaryRamSize    = SecCoreData.TemporaryRamSize * PcdGet8 (PcdFspHeapSizePercentage) / 100;
-  SecCoreData.StackBase              = (VOID*)(UINTN)((UINTN)SecCoreData.TemporaryRamBase + SecCoreData.PeiTemporaryRamSize);
-  SecCoreData.StackSize              = SecCoreData.TemporaryRamSize - SecCoreData.PeiTemporaryRamSize;
+  if (PcdGet8 (PcdFspHeapSizePercentage) == 0) {
+    SecCoreData.TemporaryRamSize       = SizeOfRam; // stack size that is going to be copied to the permanent memory
+    SecCoreData.PeiTemporaryRamBase    = SecCoreData.TemporaryRamBase;
+    SecCoreData.PeiTemporaryRamSize    = SecCoreData.TemporaryRamSize;
+    SecCoreData.StackBase              = (VOID *)GetFspEntryStack(); // Share the same boot loader stack
+    SecCoreData.StackSize              = 0;
+  } else {
+    SecCoreData.TemporaryRamSize       = SizeOfRam;
+    SecCoreData.PeiTemporaryRamBase    = SecCoreData.TemporaryRamBase;
+    SecCoreData.PeiTemporaryRamSize    = SecCoreData.TemporaryRamSize * PcdGet8 (PcdFspHeapSizePercentage) / 100;
+    SecCoreData.StackBase              = (VOID*)(UINTN)((UINTN)SecCoreData.TemporaryRamBase + SecCoreData.PeiTemporaryRamSize);
+    SecCoreData.StackSize              = SecCoreData.TemporaryRamSize - SecCoreData.PeiTemporaryRamSize;
+  }
 
   DEBUG ((DEBUG_INFO, "Fsp BootFirmwareVolumeBase - 0x%x\n", SecCoreData.BootFirmwareVolumeBase));
   DEBUG ((DEBUG_INFO, "Fsp BootFirmwareVolumeSize - 0x%x\n", SecCoreData.BootFirmwareVolumeSize));
@@ -194,15 +234,37 @@ SecTemporaryRamSupport (
   UINTN             HeapSize;
   UINTN             StackSize;
 
-  HeapSize   = CopySize * PcdGet8 (PcdFspHeapSizePercentage) / 100 ;
-  StackSize  = CopySize - HeapSize;
+  UINTN             CurrentStack;
+  UINTN             FspStackBase;
+
+  if (PcdGet8 (PcdFspHeapSizePercentage) == 0) {
 
-  OldHeap = (VOID*)(UINTN)TemporaryMemoryBase;
-  NewHeap = (VOID*)((UINTN)PermanentMemoryBase + StackSize);
+    CurrentStack = AsmReadEsp();
+    FspStackBase = (UINTN)GetFspEntryStack();
 
-  OldStack = (VOID*)((UINTN)TemporaryMemoryBase + HeapSize);
-  NewStack = (VOID*)(UINTN)PermanentMemoryBase;
+    StackSize = FspStackBase - CurrentStack;
+    HeapSize  = CopySize;
 
+    OldHeap = (VOID*)(UINTN)TemporaryMemoryBase;
+    NewHeap = (VOID*)((UINTN)PermanentMemoryBase);
+
+    OldStack = (VOID*)CurrentStack;
+    //
+    //The old stack is copied at the end of the stack region because stack grows down.
+    //
+    NewStack = (VOID*)((UINTN)PermanentMemoryBase - StackSize);
+
+  } else {
+    HeapSize   = CopySize * PcdGet8 (PcdFspHeapSizePercentage) / 100 ;
+    StackSize  = CopySize - HeapSize;
+
+    OldHeap = (VOID*)(UINTN)TemporaryMemoryBase;
+    NewHeap = (VOID*)((UINTN)PermanentMemoryBase + StackSize);
+
+    OldStack = (VOID*)((UINTN)TemporaryMemoryBase + HeapSize);
+    NewStack = (VOID*)(UINTN)PermanentMemoryBase;
+
+  }
   //
   // Migrate Heap
   //
diff --git a/IntelFsp2Pkg/FspSecCore/FspSecCoreM.inf b/IntelFsp2Pkg/FspSecCore/FspSecCoreM.inf
index dafe6f5993..0024254e0e 100644
--- a/IntelFsp2Pkg/FspSecCore/FspSecCoreM.inf
+++ b/IntelFsp2Pkg/FspSecCore/FspSecCoreM.inf
@@ -1,7 +1,7 @@
 ## @file
 #  Sec Core for FSP
 #
-#  Copyright (c) 2016 - 2018, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2016 - 2019, Intel Corporation. All rights reserved.<BR>
 #
 #  This program and the accompanying materials
 #  are licensed and made available under the terms and conditions of the BSD License
@@ -38,6 +38,7 @@
   Ia32/FspApiEntryM.nasm
   Ia32/FspApiEntryCommon.nasm
   Ia32/FspHelper.nasm
+  Ia32/ReadEsp.nasm
 
 [Binaries.Ia32]
   RAW|Vtf0/Bin/ResetVec.ia32.raw |GCC
diff --git a/IntelFsp2Pkg/FspSecCore/Ia32/FspApiEntryM.nasm b/IntelFsp2Pkg/FspSecCore/Ia32/FspApiEntryM.nasm
index 9c9a84db0a..916ad4ff0d 100644
--- a/IntelFsp2Pkg/FspSecCore/Ia32/FspApiEntryM.nasm
+++ b/IntelFsp2Pkg/FspSecCore/Ia32/FspApiEntryM.nasm
@@ -1,7 +1,7 @@
 ;; @file
 ;  Provide FSP API entry points.
 ;
-; Copyright (c) 2016 - 2018, Intel Corporation. All rights reserved.<BR>
+; Copyright (c) 2016 - 2019, Intel Corporation. All rights reserved.<BR>
 ; This program and the accompanying materials
 ; are licensed and made available under the terms and conditions of the BSD License
 ; which accompanies this distribution.  The full text of the license may be found at
@@ -19,6 +19,7 @@
 extern   ASM_PFX(PcdGet32(PcdTemporaryRamBase))
 extern   ASM_PFX(PcdGet32(PcdTemporaryRamSize))
 extern   ASM_PFX(PcdGet32(PcdFspTemporaryRamSize))
+extern   ASM_PFX(PcdGet8 (PcdFspHeapSizePercentage))
 
 struc FSPM_UPD_COMMON
     ; FSP_UPD_HEADER {
@@ -128,15 +129,55 @@ ASM_PFX(FspApiCommonContinue):
   add    edx, [eax + FSP_HEADER_CFGREG_OFFSET]
   pop    eax
 
-  FspStackSetup:
+FspStackSetup:
+  ;
+  ; StackBase = temp memory base, StackSize = temp memory size
+  ;
   mov    edi, [edx + FSPM_UPD_COMMON.StackBase]
   mov    ecx, [edx + FSPM_UPD_COMMON.StackSize]
+
+  ;
+  ; Keep using bootloader stack if heap size % is 0
+  ;
+  mov    bl, BYTE [ASM_PFX(PcdGet8 (PcdFspHeapSizePercentage))]
+  cmp    bl, 0
+  jz     SkipStackSwitch
+
+  ;
+  ; Set up a dedicated temp ram stack for FSP if FSP heap size % doesn't equal 0
+  ;
   add    edi, ecx
   ;
-  ; Setup new FSP stack
+  ; Switch to new FSP stack
   ;
-  xchg    edi, esp                                ; Exchange edi and esp, edi will be assigned to the current esp pointer and esp will be Stack base + Stack size
-  mov     ebx, esp                                ; Put Stack base + Stack size in ebx
+  xchg   edi, esp                                ; Exchange edi and esp, edi will be assigned to the current esp pointer and esp will be Stack base + Stack size
+
+SkipStackSwitch:
+  ;
+  ; If heap size % is 0:
+  ;   EDI is FSPM_UPD_COMMON.StackBase and will hold ESP later (boot loader stack pointer)
+  ;   ECX is FSPM_UPD_COMMON.StackSize
+  ;   ESP is boot loader stack pointer (no stack switch)
+  ;   BL  is 0 to indicate no stack switch (EBX will hold FSPM_UPD_COMMON.StackBase later)
+  ;
+  ; If heap size % is not 0
+  ;   EDI is boot loader stack pointer
+  ;   ECX is FSPM_UPD_COMMON.StackSize
+  ;   ESP is new stack (FSPM_UPD_COMMON.StackBase + FSPM_UPD_COMMON.StackSize)
+  ;   BL  is NOT 0 to indicate stack has switched
+  ;
+  cmp    bl, 0
+  jnz    StackHasBeenSwitched
+
+  mov    ebx, edi                                ; Put FSPM_UPD_COMMON.StackBase to ebx as temp memory base
+  mov    edi, esp                                ; Put boot loader stack pointer to edi
+  jmp    StackSetupDone
+
+StackHasBeenSwitched:
+  mov    ebx, esp                                ; Put Stack base + Stack size in ebx
+  sub    ebx, ecx                                ; Stack base + Stack size - Stack size as temp memory base
+
+StackSetupDone:
 
   ;
   ; Pass the API Idx to SecStartup
@@ -170,7 +211,6 @@ ASM_PFX(FspApiCommonContinue):
   ;
   ; Pass stack base and size into the PEI Core
   ;
-  sub     ebx, ecx            ; Stack base + Stack size - Stack size
   push    ebx
   push    ecx
 
diff --git a/IntelFsp2Pkg/FspSecCore/Ia32/ReadEsp.nasm b/IntelFsp2Pkg/FspSecCore/Ia32/ReadEsp.nasm
new file mode 100644
index 0000000000..ca29f0529c
--- /dev/null
+++ b/IntelFsp2Pkg/FspSecCore/Ia32/ReadEsp.nasm
@@ -0,0 +1,28 @@
+;; @file
+;  Provide read ESP function
+;
+; Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
+; This program and the accompanying materials
+; are licensed and made available under the terms and conditions of the BSD License
+; which accompanies this distribution.  The full text of the license may be found at
+; http://opensource.org/licenses/bsd-license.php.
+;
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+;;
+;------------------------------------------------------------------------------
+
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; UINT32
+; EFIAPI
+; AsmReadEsp (
+;   VOID
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmReadEsp)
+ASM_PFX(AsmReadEsp):
+    mov     eax, esp
+    ret
+
diff --git a/IntelFsp2Pkg/IntelFsp2Pkg.dec b/IntelFsp2Pkg/IntelFsp2Pkg.dec
index 64a31b3505..d4c6d221a1 100644
--- a/IntelFsp2Pkg/IntelFsp2Pkg.dec
+++ b/IntelFsp2Pkg/IntelFsp2Pkg.dec
@@ -86,8 +86,12 @@
   gIntelFsp2PkgTokenSpaceGuid.PcdFspBootFirmwareVolumeBase|0xFFF80000|UINT32|0x10000003
   gIntelFsp2PkgTokenSpaceGuid.PcdFspHeaderSpecVersion     |      0x20| UINT8|0x00000002
 
+  #
   # x % of FSP temporary memory will be used for heap
   # (100 - x) % of FSP temporary memory will be used for stack
+  # 0 means FSP will share the stack with boot loader and FSP temporary memory is heap
+  #   Note: This mode assumes boot loader stack is large enough for FSP to use.
+  #
   gIntelFsp2PkgTokenSpaceGuid.PcdFspHeapSizePercentage    |        50| UINT8|0x10000004
   #
   # Maximal Interrupt supported in IDT table.
-- 
2.13.3.windows.1