Re: [PATCH v3 1/2] MdePkg/BaseRngLib: Add support for ARMv8.5 RNG instructions

["Sami Mujawar" <sami.mujawar@arm.com>]

This patch looks good to me.

Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>

Regards,

Sami Mujawar


On 10/05/2021 10:53 PM, Rebecca Cran wrote:
> 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>
> ---
>   MdePkg/MdePkg.dec                                    |   9 +-
>   MdePkg/MdePkg.dsc                                    |   4 +-
>   MdePkg/Library/BaseRngLib/BaseRngLib.inf             |  23 +++-
>   MdePkg/Library/BaseRngLib/AArch64/ArmRng.h           |  43 ++++++
>   MdePkg/Library/BaseRngLib/BaseRngLibInternals.h      |  78 +++++++++++
>   MdePkg/Library/BaseRngLib/AArch64/Rndr.c             | 139 ++++++++++++++++++++
>   MdePkg/Library/BaseRngLib/BaseRng.c                  |  87 ++++++------
>   MdePkg/Library/BaseRngLib/Rand/RdRand.c              | 131 ++++++++++++++++++
>   MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.S   |  31 +++++
>   MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.asm |  30 +++++
>   MdePkg/Library/BaseRngLib/AArch64/ArmRng.S           |  37 ++++++
>   MdePkg/Library/BaseRngLib/AArch64/ArmRng.asm         |  39 ++++++
>   MdePkg/Library/BaseRngLib/BaseRngLib.uni             |   6 +-
>   13 files changed, 603 insertions(+), 54 deletions(-)
>
> diff --git a/MdePkg/MdePkg.dec b/MdePkg/MdePkg.dec
> index 8965e903e093..b49f88d8e18f 100644
> --- a/MdePkg/MdePkg.dec
> +++ b/MdePkg/MdePkg.dec
> @@ -267,6 +267,11 @@ [LibraryClasses]
>     #
>     RegisterFilterLib|Include/Library/RegisterFilterLib.h
>
> +[LibraryClasses.IA32, LibraryClasses.X64, LibraryClasses.AARCH64]
> +  ##  @libraryclass  Provides services to generate random number.
> +  #
> +  RngLib|Include/Library/RngLib.h
> +
>   [LibraryClasses.IA32, LibraryClasses.X64]
>     ##  @libraryclass  Abstracts both S/W SMI generation and detection.
>     ##
> @@ -288,10 +293,6 @@ [LibraryClasses.IA32, LibraryClasses.X64]
>     #
>     SmmPeriodicSmiLib|Include/Library/SmmPeriodicSmiLib.h
>
> -  ##  @libraryclass  Provides services to generate random number.
> -  #
> -  RngLib|Include/Library/RngLib.h
> -
>     ##  @libraryclass  Provides services to log the SMI handler registration.
>     SmiHandlerProfileLib|Include/Library/SmiHandlerProfileLib.h
>
> diff --git a/MdePkg/MdePkg.dsc b/MdePkg/MdePkg.dsc
> index d363419006ea..a94959169b2f 100644
> --- a/MdePkg/MdePkg.dsc
> +++ b/MdePkg/MdePkg.dsc
> @@ -145,6 +145,9 @@ [Components.IA32, Components.X64, Components.ARM, Components.AARCH64]
>     MdePkg/Test/UnitTest/Library/BaseSafeIntLib/TestBaseSafeIntLibSmm.inf
>     MdePkg/Test/UnitTest/Library/BaseSafeIntLib/TestBaseSafeIntLibUefiShell.inf
>
> +[Components.IA32, Components.X64, Components.AARCH64]
> +  MdePkg/Library/BaseRngLib/BaseRngLib.inf
> +
>   [Components.IA32, Components.X64]
>     MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
>     MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicSev.inf
> @@ -168,7 +171,6 @@ [Components.IA32, Components.X64]
>     MdePkg/Library/BaseS3StallLib/BaseS3StallLib.inf
>     MdePkg/Library/SmmMemLib/SmmMemLib.inf
>     MdePkg/Library/SmmIoLib/SmmIoLib.inf
> -  MdePkg/Library/BaseRngLib/BaseRngLib.inf
>     MdePkg/Library/SmmPciExpressLib/SmmPciExpressLib.inf
>     MdePkg/Library/SmiHandlerProfileLibNull/SmiHandlerProfileLibNull.inf
>     MdePkg/Library/MmServicesTableLib/MmServicesTableLib.inf
> diff --git a/MdePkg/Library/BaseRngLib/BaseRngLib.inf b/MdePkg/Library/BaseRngLib/BaseRngLib.inf
> index 31740751c69c..1fcceb941495 100644
> --- a/MdePkg/Library/BaseRngLib/BaseRngLib.inf
> +++ b/MdePkg/Library/BaseRngLib/BaseRngLib.inf
> @@ -1,9 +1,10 @@
>   ## @file
>   #  Instance of RNG (Random Number Generator) Library.
>   #
> -#  BaseRng Library that uses CPU RdRand instruction access to provide
> -#  high-quality random numbers.
> +#  BaseRng Library that uses CPU RNG instructions (e.g. RdRand) to
> +#  provide 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
> @@ -22,11 +23,25 @@ [Defines]
>     CONSTRUCTOR                    = BaseRngLibConstructor
>
>   #
> -#  VALID_ARCHITECTURES           = IA32 X64
> +#  VALID_ARCHITECTURES           = IA32 X64 AARCH64
>   #
>
> -[Sources.Ia32, Sources.X64]
> +[Sources]
>     BaseRng.c
> +  BaseRngLibInternals.h
> +
> +[Sources.Ia32, Sources.X64]
> +  Rand/RdRand.c
> +
> +[Sources.AARCH64]
> +  AArch64/Rndr.c
> +  AArch64/ArmRng.h
> +
> +  AArch64/ArmReadIdIsar0.S   | GCC
> +  AArch64/ArmRng.S           | GCC
> +
> +  AArch64/ArmReadIdIsar0.asm | MSFT
> +  AArch64/ArmRng.asm         | MSFT
>
>   [Packages]
>     MdePkg/MdePkg.dec
> diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.h b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.h
> new file mode 100644
> index 000000000000..a597e98bf0d5
> --- /dev/null
> +++ b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.h
> @@ -0,0 +1,43 @@
> +/** @file
> +  Random number generator service that uses the RNDR instruction
> +  to provide pseudorandom numbers.
> +
> +  Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#ifndef ARM_RNG_H_
> +#define ARM_RNG_H_
> +
> +/**
> +  Generates a random number using RNDR.
> +  Returns TRUE on success; FALSE on failure.
> +
> +  @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
> +ArmRndr (
> +  OUT UINT64 *Rand
> +  );
> +
> +/**
> +  Reads the ID_AA64ISAR0 Register.
> +
> +  @return The contents of the ID_AA64ISAR0 register.
> +
> +**/
> +UINT64
> +EFIAPI
> +ArmReadIdIsar0 (
> +  VOID
> +  );
> +
> +#endif /* ARM_RNG_H_ */
> +
> diff --git a/MdePkg/Library/BaseRngLib/BaseRngLibInternals.h b/MdePkg/Library/BaseRngLib/BaseRngLibInternals.h
> new file mode 100644
> index 000000000000..b6b4e9eef227
> --- /dev/null
> +++ b/MdePkg/Library/BaseRngLib/BaseRngLibInternals.h
> @@ -0,0 +1,78 @@
> +/** @file
> +
> +  Architecture specific interface to RNG functionality.
> +
> +Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
> +
> +SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#ifndef BASE_RNGLIB_INTERNALS_H_
> +
> +/**
> +  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
> +  );
> +
> +/**
> +  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
> +  );
> +
> +/**
> +  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
> +  );
> +
> +/**
> +  Checks whether the RNG instruction is supported.
> +
> +  @retval TRUE         RNG instruction is supported.
> +  @retval FALSE        RNG instruction is not supported.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +ArchIsRngSupported (
> +  VOID
> +  );
> +
> +#if defined (MDE_CPU_AARCH64)
> +
> +// RNDR, Random Number
> +#define RNDR      S3_3_C2_C4_0
> +
> +#endif
> +
> +#endif    // BASE_RNGLIB_INTERNALS_H_
> diff --git a/MdePkg/Library/BaseRngLib/AArch64/Rndr.c b/MdePkg/Library/BaseRngLib/AArch64/Rndr.c
> new file mode 100644
> index 000000000000..c9f8c813ed35
> --- /dev/null
> +++ b/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;
> +}
> diff --git a/MdePkg/Library/BaseRngLib/BaseRng.c b/MdePkg/Library/BaseRngLib/BaseRng.c
> index 7ad7aec9d38f..5b63d8f7146b 100644
> --- a/MdePkg/Library/BaseRngLib/BaseRng.c
> +++ b/MdePkg/Library/BaseRngLib/BaseRng.c
> @@ -1,8 +1,10 @@
>   /** @file
> -  Random number generator services that uses RdRand instruction access
> -  to provide high-quality random numbers.
> +  Random number generator services that uses CPU RNG instructions to
> +  provide 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
>
>   **/
> @@ -10,46 +12,15 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
>   #include <Library/BaseLib.h>
>   #include <Library/DebugLib.h>
>
> -//
> -// Bit mask used to determine if RdRand instruction is supported.
> -//
> -#define RDRAND_MASK                  BIT30
> +#include "BaseRngLibInternals.h"
>
>   //
>   // Limited retry number when valid random data is returned.
>   // Uses the recommended value defined in Section 7.3.17 of "Intel 64 and IA-32
> -// Architectures Software Developer's Mannual".
> +// Architectures Software Developer's Manual".
>   //
> -#define RDRAND_RETRY_LIMIT           10
> +#define GETRANDOM_RETRY_LIMIT           10
>
> -/**
> -  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 RETURN_SUCCESS.
> -
> -  @retval RETURN_SUCCESS   The constructor always returns EFI_SUCCESS.
> -
> -**/
> -RETURN_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);
> -
> -  return RETURN_SUCCESS;
> -}
>
>   /**
>     Generates a 16-bit random number.
> @@ -72,11 +43,19 @@ GetRandomNumber16 (
>
>     ASSERT (Rand != NULL);
>
> +  if (Rand == NULL) {
> +    return FALSE;
> +  }
> +
> +  if (!ArchIsRngSupported ()) {
> +    return FALSE;
> +  }
> +
>     //
>     // A loop to fetch a 16 bit random value with a retry count limit.
>     //
> -  for (Index = 0; Index < RDRAND_RETRY_LIMIT; Index++) {
> -    if (AsmRdRand16 (Rand)) {
> +  for (Index = 0; Index < GETRANDOM_RETRY_LIMIT; Index++) {
> +    if (ArchGetRandomNumber16 (Rand)) {
>         return TRUE;
>       }
>     }
> @@ -105,11 +84,19 @@ GetRandomNumber32 (
>
>     ASSERT (Rand != NULL);
>
> +  if (Rand == NULL) {
> +    return FALSE;
> +  }
> +
> +  if (!ArchIsRngSupported ()) {
> +    return FALSE;
> +  }
> +
>     //
>     // A loop to fetch a 32 bit random value with a retry count limit.
>     //
> -  for (Index = 0; Index < RDRAND_RETRY_LIMIT; Index++) {
> -    if (AsmRdRand32 (Rand)) {
> +  for (Index = 0; Index < GETRANDOM_RETRY_LIMIT; Index++) {
> +    if (ArchGetRandomNumber32 (Rand)) {
>         return TRUE;
>       }
>     }
> @@ -138,11 +125,19 @@ GetRandomNumber64 (
>
>     ASSERT (Rand != NULL);
>
> +  if (Rand == NULL) {
> +    return FALSE;
> +  }
> +
> +  if (!ArchIsRngSupported ()) {
> +    return FALSE;
> +  }
> +
>     //
>     // A loop to fetch a 64 bit random value with a retry count limit.
>     //
> -  for (Index = 0; Index < RDRAND_RETRY_LIMIT; Index++) {
> -    if (AsmRdRand64 (Rand)) {
> +  for (Index = 0; Index < GETRANDOM_RETRY_LIMIT; Index++) {
> +    if (ArchGetRandomNumber64 (Rand)) {
>         return TRUE;
>       }
>     }
> @@ -169,6 +164,14 @@ GetRandomNumber128 (
>   {
>     ASSERT (Rand != NULL);
>
> +  if (Rand == NULL) {
> +    return FALSE;
> +  }
> +
> +  if (!ArchIsRngSupported ()) {
> +    return FALSE;
> +  }
> +
>     //
>     // Read first 64 bits
>     //
> diff --git a/MdePkg/Library/BaseRngLib/Rand/RdRand.c b/MdePkg/Library/BaseRngLib/Rand/RdRand.c
> new file mode 100644
> index 000000000000..09fb875ac3f9
> --- /dev/null
> +++ b/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;
> +}
> diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.S b/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.S
> new file mode 100644
> index 000000000000..82a00d362212
> --- /dev/null
> +++ b/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.S
> @@ -0,0 +1,31 @@
> +#------------------------------------------------------------------------------
> +#
> +# ArmReadIdIsar0() for AArch64
> +#
> +# Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
> +#
> +# SPDX-License-Identifier: BSD-2-Clause-Patent
> +#
> +#------------------------------------------------------------------------------
> +
> +.text
> +.p2align 2
> +GCC_ASM_EXPORT(ArmReadIdIsar0)
> +
> +#/**
> +#  Reads the ID_AA64ISAR0 Register.
> +#
> +#  @return The contents of the ID_AA64ISAR0 register.
> +#
> +#**/
> +#UINT64
> +#EFIAPI
> +#ArmReadIdIsar0 (
> +#  VOID
> +#  );
> +#
> +ASM_PFX(ArmReadIdIsar0):
> +  mrs  x0, id_aa64isar0_el1 // Read ID_AA64ISAR0 Register
> +  ret
> +
> +
> diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.asm b/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.asm
> new file mode 100644
> index 000000000000..1d9f9a808c0c
> --- /dev/null
> +++ b/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.asm
> @@ -0,0 +1,30 @@
> +;------------------------------------------------------------------------------
> +;
> +; ArmReadIdIsar0() for AArch64
> +;
> +; Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
> +;
> +; SPDX-License-Identifier: BSD-2-Clause-Patent
> +;
> +;------------------------------------------------------------------------------
> +
> +  EXPORT ArmReadIdIsar0
> +  AREA BaseLib_LowLevel, CODE, READONLY
> +
> +;/**
> +;  Reads the ID_AA64ISAR0 Register.
> +;
> +; @return The contents of the ID_AA64ISAR0 register.
> +;
> +;**/
> +;UINT64
> +;EFIAPI
> +;ArmReadIdIsar0 (
> +;  VOID
> +;  );
> +;
> +ArmReadIdIsar0
> +  mrs  x0, id_aa64isar0_el1 // Read ID_AA64ISAR0 Register
> +  ret
> +
> +  END
> diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.S b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.S
> new file mode 100644
> index 000000000000..5159f467e3a6
> --- /dev/null
> +++ b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.S
> @@ -0,0 +1,37 @@
> +#------------------------------------------------------------------------------
> +#
> +# ArmRndr() for AArch64
> +#
> +# Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
> +#
> +# SPDX-License-Identifier: BSD-2-Clause-Patent
> +#
> +#------------------------------------------------------------------------------
> +
> +#include "BaseRngLibInternals.h"
> +
> +.text
> +.p2align 2
> +GCC_ASM_EXPORT(ArmRndr)
> +
> +#/**
> +#  Generates a random number using RNDR.
> +#  Returns TRUE on success; FALSE on failure.
> +#
> +#  @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
> +#ArmRndr (
> +#  OUT UINT64 *Rand
> +#  );
> +#
> +ASM_PFX(ArmRndr):
> +  mrs  x1, RNDR
> +  str  x1, [x0]
> +  cset x0, ne    // RNDR sets NZCV to 0b0100 on failure
> +  ret
> diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.asm b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.asm
> new file mode 100644
> index 000000000000..33144196cb54
> --- /dev/null
> +++ b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.asm
> @@ -0,0 +1,39 @@
> +;------------------------------------------------------------------------------
> +;
> +; ArmRndr() for AArch64
> +;
> +; Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
> +;
> +; SPDX-License-Identifier: BSD-2-Clause-Patent
> +;
> +;------------------------------------------------------------------------------
> +
> +#include "BaseRngLibInternals.h"
> +
> +  EXPORT ArmRndr
> +  AREA BaseLib_LowLevel, CODE, READONLY
> +
> +
> +;/**
> +;  Generates a random number using RNDR.
> +;  Returns TRUE on success; FALSE on failure.
> +;
> +;  @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
> +;ArmRndr (
> +;  OUT UINT64 *Rand
> +;  );
> +;
> +ArmRndr
> +  mrs  x1, RNDR
> +  str  x1, [x0]
> +  cset x0, ne    // RNDR sets NZCV to 0b0100 on failure
> +  ret
> +
> +  END
> diff --git a/MdePkg/Library/BaseRngLib/BaseRngLib.uni b/MdePkg/Library/BaseRngLib/BaseRngLib.uni
> index f3ed954c5209..de5d4f9dd869 100644
> --- a/MdePkg/Library/BaseRngLib/BaseRngLib.uni
> +++ b/MdePkg/Library/BaseRngLib/BaseRngLib.uni
> @@ -1,8 +1,8 @@
>   // /** @file
>   // Instance of RNG (Random Number Generator) Library.
>   //
> -// BaseRng Library that uses CPU RdRand instruction access to provide
> -// high-quality random numbers.
> +// BaseRng Library that uses CPU RNG instructions to provide
> +// random numbers.
>   //
>   // Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>
>   //
> @@ -13,5 +13,5 @@
>
>   #string STR_MODULE_ABSTRACT             #language en-US "Instance of RNG Library"
>
> -#string STR_MODULE_DESCRIPTION          #language en-US "BaseRng Library that uses CPU RdRand instruction access to provide high-quality random numbers"
> +#string STR_MODULE_DESCRIPTION          #language en-US "BaseRng Library that uses CPU RNG instructions to provide random numbers"
>

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