1 files changed, 72 insertions, 0 deletions
diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c
new file mode 100644
index 0000000000..e8be217f8a
--- /dev/null
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c
@@ -0,0 +1,72 @@
+/** @file
+  Aarch64 specific code.
+
+  Copyright (c) 2022, Arm Limited. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Library/BaseLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/DebugLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/ArmTrngLib.h>
+
+#include "RngDxeInternals.h"
+
+// Maximum number of Rng algorithms.
+#define RNG_AVAILABLE_ALGO_MAX  2
+
+/** Allocate and initialize mAvailableAlgoArray with the available
+    Rng algorithms. Also update mAvailableAlgoArrayCount.
+
+  @retval EFI_SUCCESS             The function completed successfully.
+  @retval EFI_OUT_OF_RESOURCES    Could not allocate memory.
+**/
+EFI_STATUS
+EFIAPI
+GetAvailableAlgorithms (
+  VOID
+  )
+{
+  UINT64  DummyRand;
+  UINT16  MajorRevision;
+  UINT16  MinorRevision;
+
+  // Rng algorithms 2 times, one for the allocation, one to populate.
+  mAvailableAlgoArray = AllocateZeroPool (RNG_AVAILABLE_ALGO_MAX);
+  if (mAvailableAlgoArray == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  // Check RngGetBytes() before advertising PcdCpuRngSupportedAlgorithm.
+  if (!EFI_ERROR (RngGetBytes (sizeof (DummyRand), (UINT8 *)&DummyRand))) {
+    CopyMem (
+      &mAvailableAlgoArray[mAvailableAlgoArrayCount],
+      PcdGetPtr (PcdCpuRngSupportedAlgorithm),
+      sizeof (EFI_RNG_ALGORITHM)
+      );
+    mAvailableAlgoArrayCount++;
+
+    DEBUG_CODE_BEGIN ();
+    if (IsZeroGuid (PcdGetPtr (PcdCpuRngSupportedAlgorithm))) {
+      DEBUG ((
+        DEBUG_WARN,
+        "PcdCpuRngSupportedAlgorithm should be a non-zero GUID\n"
+        ));
+    }
+
+    DEBUG_CODE_END ();
+  }
+
+  // Raw algorithm (Trng)
+  if (!EFI_ERROR (GetArmTrngVersion (&MajorRevision, &MinorRevision))) {
+    CopyMem (
+      &mAvailableAlgoArray[mAvailableAlgoArrayCount],
+      &gEfiRngAlgorithmRaw,
+      sizeof (EFI_RNG_ALGORITHM)
+      );
+    mAvailableAlgoArrayCount++;
+  }
+
+  return EFI_SUCCESS;
+}