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1715d67231
A ArmReadIdAA64Isar0Reg() function was recently added to BaseLib. Use it instead of its ArmReadIdIsar0() equivalent, which was private to the BaseRngLib library. This also allows to avoid the confusion between the following registers: - ID_ISAR0_EL1: allows to probe for Divide instructions, Debug instructions, ... - ID_AA64ISAR0_EL1: AARCH64 specific register allowing to probe for AESE, RNDR, ... instructions Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
176 lines
3.8 KiB
C
176 lines
3.8 KiB
C
/** @file
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Random number generator service that uses the RNDR instruction
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to provide pseudorandom numbers.
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Copyright (c) 2023, Arm Limited. All rights reserved.<BR>
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Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
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Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include <Uefi.h>
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#include <Library/BaseLib.h>
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#include <Library/BaseMemoryLib.h>
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#include <Library/DebugLib.h>
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#include <Library/RngLib.h>
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#include "ArmRng.h"
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#include "BaseRngLibInternals.h"
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STATIC BOOLEAN mRndrSupported;
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/**
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The constructor function checks whether or not RNDR instruction is supported
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by the host hardware.
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The constructor function checks whether or not RNDR instruction is supported.
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It will ASSERT() if RNDR instruction is not supported.
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It will always return EFI_SUCCESS.
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@retval EFI_SUCCESS The constructor always returns EFI_SUCCESS.
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**/
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EFI_STATUS
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EFIAPI
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BaseRngLibConstructor (
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VOID
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)
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{
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UINT64 Isar0;
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//
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// Determine RNDR support by examining bits 63:60 of the ISAR0 register returned by
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// MSR. A non-zero value indicates that the processor supports the RNDR instruction.
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//
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Isar0 = ArmReadIdAA64Isar0Reg ();
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mRndrSupported = !!((Isar0 >> ARM_ID_AA64ISAR0_EL1_RNDR_SHIFT) & ARM_ID_AA64ISAR0_EL1_RNDR_MASK);
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return EFI_SUCCESS;
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}
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/**
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Generates a 16-bit random number.
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@param[out] Rand Buffer pointer to store the 16-bit random value.
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@retval TRUE Random number generated successfully.
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@retval FALSE Failed to generate the random number.
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**/
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BOOLEAN
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EFIAPI
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ArchGetRandomNumber16 (
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OUT UINT16 *Rand
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)
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{
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UINT64 Rand64;
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if (ArchGetRandomNumber64 (&Rand64)) {
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*Rand = Rand64 & MAX_UINT16;
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return TRUE;
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}
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return FALSE;
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}
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/**
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Generates a 32-bit random number.
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@param[out] Rand Buffer pointer to store the 32-bit random value.
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@retval TRUE Random number generated successfully.
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@retval FALSE Failed to generate the random number.
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**/
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BOOLEAN
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EFIAPI
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ArchGetRandomNumber32 (
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OUT UINT32 *Rand
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)
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{
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UINT64 Rand64;
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if (ArchGetRandomNumber64 (&Rand64)) {
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*Rand = Rand64 & MAX_UINT32;
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return TRUE;
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}
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return FALSE;
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}
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/**
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Generates a 64-bit random number.
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@param[out] Rand Buffer pointer to store the 64-bit random value.
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@retval TRUE Random number generated successfully.
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@retval FALSE Failed to generate the random number.
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**/
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BOOLEAN
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EFIAPI
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ArchGetRandomNumber64 (
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OUT UINT64 *Rand
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)
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{
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return ArmRndr (Rand);
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}
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/**
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Checks whether RNDR is supported.
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@retval TRUE RNDR is supported.
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@retval FALSE RNDR is not supported.
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**/
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BOOLEAN
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EFIAPI
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ArchIsRngSupported (
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VOID
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)
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{
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return mRndrSupported;
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}
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/**
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Get a GUID identifying the RNG algorithm implementation.
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@param [out] RngGuid If success, contains the GUID identifying
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the RNG algorithm implementation.
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@retval EFI_SUCCESS Success.
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@retval EFI_UNSUPPORTED Not supported.
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@retval EFI_INVALID_PARAMETER Invalid parameter.
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**/
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EFI_STATUS
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EFIAPI
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GetRngGuid (
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GUID *RngGuid
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)
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{
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GUID *RngLibGuid;
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if (RngGuid == NULL) {
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return EFI_INVALID_PARAMETER;
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}
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if (!mRndrSupported) {
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return EFI_UNSUPPORTED;
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}
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//
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// If the platform advertises the algorithm behind RNDR instruction,
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// use it. Otherwise use gEfiRngAlgorithmArmRndr.
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//
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RngLibGuid = PcdGetPtr (PcdCpuRngSupportedAlgorithm);
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if (!IsZeroGuid (RngLibGuid)) {
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CopyMem (RngGuid, RngLibGuid, sizeof (*RngGuid));
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} else {
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CopyMem (RngGuid, &gEfiRngAlgorithmArmRndr, sizeof (*RngGuid));
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}
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return EFI_SUCCESS;
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}
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