MdePkg/DxeRngLib: Add gEfiRngAlgorithmArmRndr to the secure algorithms

DxeRngLib iterates over a list of secure algorithms before trying
to use the default algorithm provided by the Rng protocol. Add
gEfiRngAlgorithmArmRndr to this list. The algorithm represented by
this GUID is a secure DRBG of an unknown type, implemented by the
aarch64 RNDR instruction.
On AARCH64 platform, use the RNDR instruction as the first option
if it is available.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>

MdePkg/Library/DxeRngLib/DxeRngLib.c

@@ -33,6 +33,13 @@ typedef struct {
 // the RNG protocol and are generally considered secure.
 //
 GLOBAL_REMOVE_IF_UNREFERENCED SECURE_RNG_ALGO_ARRAY  mSecureHashAlgorithms[] = {
+ #ifdef MDE_CPU_AARCH64
+  {
+    &gEfiRngAlgorithmArmRndr, // unspecified SP800-90A DRBG (through RNDR instr.)
+    "ARM-RNDR",
+    FALSE,
+  },
+ #endif
   {
     &gEfiRngAlgorithmSp80090Ctr256Guid,  // SP800-90A DRBG CTR using AES-256
     "DRBG-CTR",

MdePkg/Library/DxeRngLib/DxeRngLib.inf

@@ -40,5 +40,8 @@
   gEfiRngAlgorithmSp80090Hmac256Guid
   gEfiRngAlgorithmRaw
 
+[Guids.AARCH64]
+  gEfiRngAlgorithmArmRndr
+
 [FixedPcd]
   gEfiMdePkgTokenSpaceGuid.PcdEnforceSecureRngAlgorithms ## CONSUMES