SecurityPkg Variable: Remove mStorageData buffer allocation and use Scratch buffer instead to reduce SMRAM consumption.

It can reduce MAX (PcdGet32 (PcdMaxVariableSize), PcdGet32 (PcdMaxHardwareErrorVariableSize)) size of SMRAM consumption.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Guo Dong <guo.dong@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14855 6f19259b-4bc3-4df7-8a09-765794883524

SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.c

@@ -48,14 +48,6 @@ CONST UINT8 mRsaE[] = { 0x01, 0x00, 0x01 };
 //
 VOID  *mHashCtx = NULL;
 
-//
-// Pointer to runtime buffer.
-// For "Append" operation to an existing variable, a read/modify/write operation
-// is supported by firmware internally. Reserve runtime buffer to cache previous
-// variable data in runtime phase because memory allocation is forbidden in virtual mode.
-//
-VOID  *mStorageArea = NULL;
-
 //
 // The serialization of the values of the VariableName, VendorGuid and Attributes
 // parameters of the SetVariable() call and the TimeStamp component of the
@@ -191,14 +183,6 @@ AutenticatedVariableServiceInitialize (
     return EFI_OUT_OF_RESOURCES;
   }
 
-  //
-  // Reserved runtime buffer for "Append" operation in virtual mode.
-  //
-  mStorageArea  = AllocateRuntimePool (MAX (PcdGet32 (PcdMaxVariableSize), PcdGet32 (PcdMaxHardwareErrorVariableSize)));
-  if (mStorageArea == NULL) {
-    return EFI_OUT_OF_RESOURCES;
-  }
-
   //
   // Prepare runtime buffer for serialized data of time-based authenticated
   // Variable, i.e. (VariableName, VendorGuid, Attributes, TimeStamp, Data).

SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.h

@@ -329,7 +329,6 @@ VerifyTimeBasedPayload (
 extern UINT8  mPubKeyStore[MAX_KEYDB_SIZE];
 extern UINT32 mPubKeyNumber;
 extern VOID   *mHashCtx;
-extern VOID   *mStorageArea;
 extern UINT8  *mSerializationRuntimeBuffer;
 
 #endif

SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.c

@@ -1752,7 +1752,9 @@ UpdateVariable (
   VARIABLE_POINTER_TRACK              NvVariable;
   VARIABLE_STORE_HEADER               *VariableStoreHeader;
   UINTN                               CacheOffset;
-  UINTN                               BufSize;
+  UINT8                               *BufferForMerge;
+  UINTN                               MergedBufSize;
+  BOOLEAN                             DataReady;
   UINTN                               DataOffset;
 
   if (mVariableModuleGlobal->FvbInstance == NULL) {
@@ -1802,7 +1804,8 @@ UpdateVariable (
   //
   NextVariable = GetEndPointer ((VARIABLE_STORE_HEADER *) ((UINTN) mVariableModuleGlobal->VariableGlobal.VolatileVariableBase));
   ScratchSize = MAX (PcdGet32 (PcdMaxVariableSize), PcdGet32 (PcdMaxHardwareErrorVariableSize));
-
+  SetMem (NextVariable, ScratchSize, 0xff);
+  DataReady = FALSE;
 
   if (Variable->CurrPtr != NULL) {
     //
@@ -1911,42 +1914,42 @@ UpdateVariable (
       //
       if ((Attributes & EFI_VARIABLE_APPEND_WRITE) != 0) {
         //
-        // Cache the previous variable data into StorageArea.
+        // NOTE: From 0 to DataOffset of NextVariable is reserved for Variable Header and Name.
+        // From DataOffset of NextVariable is to save the existing variable data.
         //
         DataOffset = sizeof (VARIABLE_HEADER) + Variable->CurrPtr->NameSize + GET_PAD_SIZE (Variable->CurrPtr->NameSize);
-        CopyMem (mStorageArea, (UINT8*)((UINTN) Variable->CurrPtr + DataOffset), Variable->CurrPtr->DataSize);
+        BufferForMerge = (UINT8 *) ((UINTN) NextVariable + DataOffset);
+        CopyMem (BufferForMerge, (UINT8 *) ((UINTN) Variable->CurrPtr + DataOffset), Variable->CurrPtr->DataSize);
 
         //
         // Set Max Common Variable Data Size as default MaxDataSize 
         //
-        MaxDataSize = PcdGet32 (PcdMaxVariableSize) - sizeof (VARIABLE_HEADER) - StrSize (VariableName) - GET_PAD_SIZE (StrSize (VariableName));
+        MaxDataSize = PcdGet32 (PcdMaxVariableSize) - DataOffset;
-
 
         if ((CompareGuid (VendorGuid, &gEfiImageSecurityDatabaseGuid) &&
             ((StrCmp (VariableName, EFI_IMAGE_SECURITY_DATABASE) == 0) || (StrCmp (VariableName, EFI_IMAGE_SECURITY_DATABASE1) == 0))) ||
             (CompareGuid (VendorGuid, &gEfiGlobalVariableGuid) && (StrCmp (VariableName, EFI_KEY_EXCHANGE_KEY_NAME) == 0))) {
-
           //
           // For variables with formatted as EFI_SIGNATURE_LIST, the driver shall not perform an append of
           // EFI_SIGNATURE_DATA values that are already part of the existing variable value.
           //
           Status = AppendSignatureList (
-                     mStorageArea, 
+                     BufferForMerge,
                      Variable->CurrPtr->DataSize, 
                      MaxDataSize - Variable->CurrPtr->DataSize,
                      Data,
                      DataSize,
-                     &BufSize
+                     &MergedBufSize
                      );
           if (Status == EFI_BUFFER_TOO_SMALL) {
             //
-            // Signture List is too long, Failed to Append
+            // Signature List is too long, Failed to Append.
             //
             Status = EFI_INVALID_PARAMETER;
             goto Done;
           }
 
-          if (BufSize == Variable->CurrPtr->DataSize) {
+          if (MergedBufSize == Variable->CurrPtr->DataSize) {
             if ((TimeStamp == NULL) || CompareTimeStamp (TimeStamp, &Variable->CurrPtr->TimeStamp)) {
               //
               // New EFI_SIGNATURE_DATA is not found and timestamp is not later
@@ -1959,29 +1962,30 @@ UpdateVariable (
           }
         } else {
           //
-          // For other Variables, append the new data to the end of previous data.
+          // For other Variables, append the new data to the end of existing data.
           // Max Harware error record variable data size is different from common variable
           //
           if ((Attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD) == EFI_VARIABLE_HARDWARE_ERROR_RECORD) {
-            MaxDataSize = PcdGet32 (PcdMaxHardwareErrorVariableSize) - sizeof (VARIABLE_HEADER) - StrSize (VariableName) - GET_PAD_SIZE (StrSize (VariableName));
+            MaxDataSize = PcdGet32 (PcdMaxHardwareErrorVariableSize) - DataOffset;
           }
 
           if (Variable->CurrPtr->DataSize + DataSize > MaxDataSize) {
             //
-            // Exsiting data + Appended data exceed maximum variable size limitation 
+            // Existing data size + new data size exceed maximum variable size limitation.
             //
             Status = EFI_INVALID_PARAMETER;
             goto Done;
           }
-          CopyMem ((UINT8*)((UINTN) mStorageArea + Variable->CurrPtr->DataSize), Data, DataSize);
+          CopyMem ((UINT8*) ((UINTN) BufferForMerge + Variable->CurrPtr->DataSize), Data, DataSize);
-          BufSize = Variable->CurrPtr->DataSize + DataSize;
+          MergedBufSize = Variable->CurrPtr->DataSize + DataSize;
         }
 
         //
-        // Override Data and DataSize which are used for combined data area including previous and new data.
+        // BufferForMerge(from DataOffset of NextVariable) has included the merged existing and new data.
         //
-        Data     = mStorageArea;
+        Data      = BufferForMerge;
-        DataSize = BufSize;
+        DataSize  = MergedBufSize;
+        DataReady = TRUE;
       }
 
       //
@@ -2038,9 +2042,7 @@ UpdateVariable (
   //
   // Function part - create a new variable and copy the data.
   // Both update a variable and create a variable will come here.
-
+  //
-  SetMem (NextVariable, ScratchSize, 0xff);
-
   NextVariable->StartId     = VARIABLE_DATA;
   //
   // NextVariable->State = VAR_ADDED;
@@ -2082,11 +2084,19 @@ UpdateVariable (
     VarNameSize
     );
   VarDataOffset = VarNameOffset + VarNameSize + GET_PAD_SIZE (VarNameSize);
+
+  //
+  // If DataReady is TRUE, it means the variable data has been saved into
+  // NextVariable during EFI_VARIABLE_APPEND_WRITE operation preparation.
+  //
+  if (!DataReady) {
     CopyMem (
       (UINT8 *) ((UINTN) NextVariable + VarDataOffset),
       Data,
       DataSize
       );
+  }
+
   CopyMem (&NextVariable->VendorGuid, VendorGuid, sizeof (EFI_GUID));
   //
   // There will be pad bytes after Data, the NextVariable->NameSize and

SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableDxe.c

@@ -241,7 +241,6 @@ VariableClassAddressChangeEvent (
   EfiConvertPointer (0x0, (VOID **) &mVariableModuleGlobal->VariableGlobal.VolatileVariableBase);
   EfiConvertPointer (0x0, (VOID **) &mVariableModuleGlobal);
   EfiConvertPointer (0x0, (VOID **) &mHashCtx);
-  EfiConvertPointer (0x0, (VOID **) &mStorageArea);
   EfiConvertPointer (0x0, (VOID **) &mSerializationRuntimeBuffer);
   EfiConvertPointer (0x0, (VOID **) &mNvVariableCache);