SecurityPkg: Add support for RngDxe on AARCH64

AARCH64 support has been added to BaseRngLib via the optional
ARMv8.5 FEAT_RNG.

Refactor RngDxe to support AARCH64, note support for it in the
VALID_ARCHITECTURES line of RngDxe.inf and enable it in SecurityPkg.dsc.

Signed-off-by: Rebecca Cran <rebecca@nuviainc.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>

SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RdRand.c

@@ -0,0 +1,128 @@
+/** @file
+  Support routines for RDRAND instruction access.
+
+Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
+(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+#include <Library/RngLib.h>
+
+#include "AesCore.h"
+#include "RdRand.h"
+#include "RngDxeInternals.h"
+
+/**
+  Creates a 128bit random value that is fully forward and backward prediction resistant,
+  suitable for seeding a NIST SP800-90 Compliant, FIPS 1402-2 certifiable SW DRBG.
+  This function takes multiple random numbers through RDRAND without intervening
+  delays to ensure reseeding and performs AES-CBC-MAC over the data to compute the
+  seed value.
+
+  @param[out]  SeedBuffer    Pointer to a 128bit buffer to store the random seed.
+
+  @retval EFI_SUCCESS        Random seed generation succeeded.
+  @retval EFI_NOT_READY      Failed to request random bytes.
+
+**/
+EFI_STATUS
+EFIAPI
+RdRandGetSeed128 (
+  OUT UINT8        *SeedBuffer
+  )
+{
+  EFI_STATUS  Status;
+  UINT8       RandByte[16];
+  UINT8       Key[16];
+  UINT8       Ffv[16];
+  UINT8       Xored[16];
+  UINT32      Index;
+  UINT32      Index2;
+
+  //
+  // Chose an arbitrary key and zero the feed_forward_value (FFV)
+  //
+  for (Index = 0; Index < 16; Index++) {
+    Key[Index] = (UINT8) Index;
+    Ffv[Index] = 0;
+  }
+
+  //
+  // Perform CBC_MAC over 32 * 128 bit values, with 10us gaps between 128 bit value
+  // The 10us gaps will ensure multiple reseeds within the HW RNG with a large design margin.
+  //
+  for (Index = 0; Index < 32; Index++) {
+    MicroSecondDelay (10);
+    Status = RngGetBytes (16, RandByte);
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
+
+    //
+    // Perform XOR operations on two 128-bit value.
+    //
+    for (Index2 = 0; Index2 < 16; Index2++) {
+      Xored[Index2] = RandByte[Index2] ^ Ffv[Index2];
+    }
+
+    AesEncrypt (Key, Xored, Ffv);
+  }
+
+  for (Index = 0; Index < 16; Index++) {
+    SeedBuffer[Index] = Ffv[Index];
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Generate high-quality entropy source through RDRAND.
+
+  @param[in]   Length        Size of the buffer, in bytes, to fill with.
+  @param[out]  Entropy       Pointer to the buffer to store the entropy data.
+
+  @retval EFI_SUCCESS        Entropy generation succeeded.
+  @retval EFI_NOT_READY      Failed to request random data.
+
+**/
+EFI_STATUS
+EFIAPI
+RdRandGenerateEntropy (
+  IN UINTN         Length,
+  OUT UINT8        *Entropy
+  )
+{
+  EFI_STATUS  Status;
+  UINTN       BlockCount;
+  UINT8       Seed[16];
+  UINT8       *Ptr;
+
+  Status     = EFI_NOT_READY;
+  BlockCount = Length / 16;
+  Ptr        = (UINT8 *)Entropy;
+
+  //
+  // Generate high-quality seed for DRBG Entropy
+  //
+  while (BlockCount > 0) {
+    Status = RdRandGetSeed128 (Seed);
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
+    CopyMem (Ptr, Seed, 16);
+
+    BlockCount--;
+    Ptr = Ptr + 16;
+  }
+
+  //
+  // Populate the remained data as request.
+  //
+  Status = RdRandGetSeed128 (Seed);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+  CopyMem (Ptr, Seed, (Length % 16));
+
+  return Status;
+}