/** @file | |
Random number generator service that uses the RNDR instruction | |
to provide pseudorandom numbers. | |
Copyright (c) 2023, Arm Limited. All rights reserved.<BR> | |
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/BaseMemoryLib.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 (); | |
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; | |
} | |
/** | |
Get a GUID identifying the RNG algorithm implementation. | |
@param [out] RngGuid If success, contains the GUID identifying | |
the RNG algorithm implementation. | |
@retval EFI_SUCCESS Success. | |
@retval EFI_UNSUPPORTED Not supported. | |
@retval EFI_INVALID_PARAMETER Invalid parameter. | |
**/ | |
EFI_STATUS | |
EFIAPI | |
GetRngGuid ( | |
GUID *RngGuid | |
) | |
{ | |
GUID *RngLibGuid; | |
if (RngGuid == NULL) { | |
return EFI_INVALID_PARAMETER; | |
} | |
if (!mRndrSupported) { | |
return EFI_UNSUPPORTED; | |
} | |
// | |
// If the platform advertises the algorithm behind RNDR instruction, | |
// use it. Otherwise use gEfiRngAlgorithmArmRndr. | |
// | |
RngLibGuid = PcdGetPtr (PcdCpuRngSupportedAlgorithm); | |
if (!IsZeroGuid (RngLibGuid)) { | |
CopyMem (RngGuid, RngLibGuid, sizeof (*RngGuid)); | |
} else { | |
CopyMem (RngGuid, &gEfiRngAlgorithmArmRndr, sizeof (*RngGuid)); | |
} | |
return EFI_SUCCESS; | |
} |