[PATCH v2 1/1] MdeModulePkg/PiSmmCore: Pad POOL_HEADER to be 8-byte aligned

[Hao Wu <hao.a.wu@intel.com>]

According to the PI spec (Vol 4, Section 3.2 SmmAllocatePool()):
The SmmAllocatePool() function ... All allocations are eight-byte aligned.

The commit adds a padding field in structure 'POOL_HEADER' to ensure the
above requirement is met.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
---
 MdeModulePkg/Core/PiSmmCore/PiSmmCore.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h
index c12805a2dd..0692661114 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h
@@ -1200,6 +1200,14 @@ typedef struct {
   UINTN           Size;
   BOOLEAN         Available;
   EFI_MEMORY_TYPE Type;
+  //
+  // According to the PI spec, buffers allocated by SmmAllocatePool should
+  // be 8-byte aligned. Here, the pad bytes make sure that the structure
+  // is 8-byte aligned:
+  // For IA32, sizeof (POOL_HEADER) is 16.
+  // For X64, sizeof (POOL_HEADER) is 24.
+  //
+  UINT32          Padding;
 } POOL_HEADER;
 
 typedef struct {
-- 
2.12.0.windows.1