Rndr.c

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#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;
 
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          = ArmReadIdAA64Isar0Reg ();
  mRndrSupported = !!((Isar0 >> ARM_ID_AA64ISAR0_EL1_RNDR_SHIFT) & ARM_ID_AA64ISAR0_EL1_RNDR_MASK);
 
  return EFI_SUCCESS;
}
 
BOOLEAN
EFIAPI
ArchGetRandomNumber16 (
  OUT     UINT16  *Rand
  )
{
  UINT64  Rand64;
 
  if (ArchGetRandomNumber64 (&Rand64)) {
    *Rand = Rand64 & MAX_UINT16;
    return TRUE;
  }
 
  return FALSE;
}
 
BOOLEAN
EFIAPI
ArchGetRandomNumber32 (
  OUT     UINT32  *Rand
  )
{
  UINT64  Rand64;
 
  if (ArchGetRandomNumber64 (&Rand64)) {
    *Rand = Rand64 & MAX_UINT32;
    return TRUE;
  }
 
  return FALSE;
}
 
BOOLEAN
EFIAPI
ArchGetRandomNumber64 (
  OUT     UINT64  *Rand
  )
{
  return ArmRndr (Rand);
}
 
BOOLEAN
EFIAPI
ArchIsRngSupported (
  VOID
  )
{
  return mRndrSupported;
}
 
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;
}