MdePkg/BaseRngLib: Add support for ARMv8.5 RNG instructions

Make BaseRngLib more generic by moving x86-specific functionality into
'Rand' and adding files under 'AArch64' to support the optional ARMv8.5
RNG instruction RNDR that is a part of FEAT_RNG.

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

MdePkg/Library/BaseRngLib/Rand/RdRand.c

@@ -0,0 +1,131 @@
+/** @file
+  Random number generator services that uses RdRand instruction access
+  to provide high-quality random numbers.
+
+Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
+Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>
+
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Uefi.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+
+#include "BaseRngLibInternals.h"
+
+//
+// Bit mask used to determine if RdRand instruction is supported.
+//
+#define RDRAND_MASK                  BIT30
+
+
+STATIC BOOLEAN mRdRandSupported;
+
+/**
+  The constructor function checks whether or not RDRAND instruction is supported
+  by the host hardware.
+
+  The constructor function checks whether or not RDRAND instruction is supported.
+  It will ASSERT() if RDRAND instruction is not supported.
+  It will always return EFI_SUCCESS.
+
+  @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
+
+**/
+EFI_STATUS
+EFIAPI
+BaseRngLibConstructor (
+  VOID
+  )
+{
+  UINT32  RegEcx;
+
+  //
+  // Determine RDRAND support by examining bit 30 of the ECX register returned by
+  // CPUID. A value of 1 indicates that processor support RDRAND instruction.
+  //
+  AsmCpuid (1, 0, 0, &RegEcx, 0);
+  ASSERT ((RegEcx & RDRAND_MASK) == RDRAND_MASK);
+
+  mRdRandSupported = ((RegEcx & RDRAND_MASK) == RDRAND_MASK);
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Generates a 16-bit random number.
+
+  @param[out] Rand     Buffer pointer to store the 16-bit random value.
+
+  @retval TRUE         Random number generated successfully.
+  @retval FALSE        Failed to generate the random number.
+
+**/
+BOOLEAN
+EFIAPI
+ArchGetRandomNumber16 (
+  OUT     UINT16                    *Rand
+  )
+{
+  return AsmRdRand16 (Rand);
+}
+
+/**
+  Generates a 32-bit random number.
+
+  @param[out] Rand     Buffer pointer to store the 32-bit random value.
+
+  @retval TRUE         Random number generated successfully.
+  @retval FALSE        Failed to generate the random number.
+
+**/
+BOOLEAN
+EFIAPI
+ArchGetRandomNumber32 (
+  OUT     UINT32                    *Rand
+  )
+{
+  return AsmRdRand32 (Rand);
+}
+
+/**
+  Generates a 64-bit random number.
+
+  @param[out] Rand     Buffer pointer to store the 64-bit random value.
+
+  @retval TRUE         Random number generated successfully.
+  @retval FALSE        Failed to generate the random number.
+
+**/
+BOOLEAN
+EFIAPI
+ArchGetRandomNumber64 (
+  OUT     UINT64                    *Rand
+  )
+{
+  return AsmRdRand64 (Rand);
+}
+
+/**
+  Checks whether RDRAND is supported.
+
+  @retval TRUE         RDRAND is supported.
+  @retval FALSE        RDRAND is not supported.
+
+**/
+BOOLEAN
+EFIAPI
+ArchIsRngSupported (
+  VOID
+  )
+{
+  /*
+     Existing software depends on this always returning TRUE, so for
+     now hard-code it.
+
+     return mRdRandSupported;
+  */
+  return TRUE;
+}