EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.c

   1 /** @file
   2
   3   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   4
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include <Uefi.h>
  10
  11 #include <Library/BaseLib.h>
  12 #include <Library/DebugLib.h>
  13 #include <Library/UefiBootServicesTableLib.h>
  14 #include <Library/UefiRuntimeServicesTableLib.h>
  15
  16 #include <Protocol/MonotonicCounter.h>
  17
  18 UINT64  gCurrentMonotonicCount = 0;
  19
  20 EFI_STATUS
  21 EFIAPI
  22 GetNextMonotonicCount (
  23   OUT UINT64  *Count
  24   )
  25 {
  26   if (Count == NULL) {
  27     return EFI_INVALID_PARAMETER;
  28   }
  29
  30   *Count = gCurrentMonotonicCount++;
  31   return EFI_SUCCESS;
  32 }
  33
  34 EFI_STATUS
  35 EFIAPI
  36 GetNextHighMonotonicCount (
  37   OUT UINT32  *HighCount
  38   )
  39 {
  40   if (HighCount == NULL) {
  41     return EFI_INVALID_PARAMETER;
  42   }
  43
  44   gCurrentMonotonicCount += 0x0000000100000000ULL;
  45
  46   *HighCount = (UINT32)RShiftU64 (gCurrentMonotonicCount, 32) & 0xFFFFFFFF;
  47
  48   return EFI_SUCCESS;
  49 }
  50
  51 EFI_STATUS
  52 EFIAPI
  53 MonotonicCounterDriverInitialize (
  54   IN EFI_HANDLE        ImageHandle,
  55   IN EFI_SYSTEM_TABLE  *SystemTable
  56   )
  57 {
  58   EFI_STATUS  Status;
  59   EFI_HANDLE  Handle = NULL;
  60
  61   // Make sure the Monotonic Counter Architectural Protocol is not already installed in the system
  62   ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiMonotonicCounterArchProtocolGuid);
  63
  64   // Fill in the EFI Boot Services and EFI Runtime Services Monotonic Counter Fields
  65   gBS->GetNextMonotonicCount     = GetNextMonotonicCount;
  66   gRT->GetNextHighMonotonicCount = GetNextHighMonotonicCount;
  67
  68   // Install the Monotonic Counter Architectural Protocol onto a new handle
  69   Status = gBS->InstallMultipleProtocolInterfaces (
  70                   &Handle,
  71                   &gEfiMonotonicCounterArchProtocolGuid,
  72                   NULL,
  73                   NULL
  74                   );
  75   return Status;
  76 }