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/AArch64/Rndr.c

@@ -0,0 +1,139 @@
+/** @file
+  Random number generator service that uses the RNDR instruction
+  to provide pseudorandom 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 <Library/RngLib.h>
+
+#include "ArmRng.h"
+#include "BaseRngLibInternals.h"
+
+STATIC BOOLEAN mRndrSupported;
+
+//
+// Bit mask used to determine if RNDR instruction is supported.
+//
+#define RNDR_MASK                  ((UINT64)MAX_UINT16 << 60U)
+
+/**
+  The constructor function checks whether or not RNDR instruction is supported
+  by the host hardware.
+
+  The constructor function checks whether or not RNDR instruction is supported.
+  It will ASSERT() if RNDR instruction is not supported.
+  It will always return EFI_SUCCESS.
+
+  @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
+
+**/
+EFI_STATUS
+EFIAPI
+BaseRngLibConstructor (
+  VOID
+  )
+{
+  UINT64 Isar0;
+  //
+  // Determine RNDR support by examining bits 63:60 of the ISAR0 register returned by
+  // MSR. A non-zero value indicates that the processor supports the RNDR instruction.
+  //
+  Isar0 = ArmReadIdIsar0 ();
+  ASSERT ((Isar0 & RNDR_MASK) != 0);
+
+  mRndrSupported = ((Isar0 & RNDR_MASK) != 0);
+
+  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
+  )
+{
+  UINT64 Rand64;
+
+  if (ArchGetRandomNumber64 (&Rand64)) {
+    *Rand = Rand64 & MAX_UINT16;
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
+/**
+  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
+  )
+{
+  UINT64 Rand64;
+
+  if (ArchGetRandomNumber64 (&Rand64)) {
+    *Rand = Rand64 & MAX_UINT32;
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
+/**
+  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 ArmRndr (Rand);
+}
+
+/**
+  Checks whether RNDR is supported.
+
+  @retval TRUE         RNDR is supported.
+  @retval FALSE        RNDR is not supported.
+
+**/
+BOOLEAN
+EFIAPI
+ArchIsRngSupported (
+  VOID
+  )
+{
+  return mRndrSupported;
+}