EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.c

   1 /** @file
   2
   3   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   4
   5   This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #include <Uefi.h>
  16
  17 #include <Library/BaseLib.h>
  18 #include <Library/DebugLib.h>
  19 #include <Library/UefiBootServicesTableLib.h>
  20 #include <Library/UefiRuntimeServicesTableLib.h>
  21
  22 #include <Protocol/MonotonicCounter.h>
  23
  24 UINT64 gCurrentMonotonicCount = 0;
  25
  26 EFI_STATUS
  27 EFIAPI
  28 GetNextMonotonicCount (
  29   OUT UINT64  *Count
  30   )
  31 {
  32   if (Count == NULL) {
  33     return EFI_INVALID_PARAMETER;
  34   }
  35
  36   *Count = gCurrentMonotonicCount++;
  37   return EFI_SUCCESS;
  38 }
  39
  40 EFI_STATUS
  41 EFIAPI
  42 GetNextHighMonotonicCount (
  43   OUT UINT32  *HighCount
  44   )
  45 {
  46   if (HighCount == NULL) {
  47     return EFI_INVALID_PARAMETER;
  48   }
  49
  50   gCurrentMonotonicCount += 0x0000000100000000ULL;
  51
  52   *HighCount = (UINT32)RShiftU64 (gCurrentMonotonicCount, 32) & 0xFFFFFFFF;
  53
  54   return EFI_SUCCESS;
  55 }
  56
  57
  58 EFI_STATUS
  59 EFIAPI
  60 MonotonicCounterDriverInitialize (
  61   IN EFI_HANDLE        ImageHandle,
  62   IN EFI_SYSTEM_TABLE  *SystemTable
  63   )
  64 {
  65   EFI_STATUS  Status;
  66   EFI_HANDLE  Handle = NULL;
  67
  68   // Make sure the Monotonic Counter Architectural Protocol is not already installed in the system
  69   ASSERT_PROTOCOL_ALREADY_INSTALLED(NULL, &gEfiMonotonicCounterArchProtocolGuid);
  70
  71   // Fill in the EFI Boot Services and EFI Runtime Services Monotonic Counter Fields
  72   gBS->GetNextMonotonicCount     = GetNextMonotonicCount;
  73   gRT->GetNextHighMonotonicCount = GetNextHighMonotonicCount;
  74
  75   // Install the Monotonic Counter Architectural Protocol onto a new handle
  76   Status = gBS->InstallMultipleProtocolInterfaces (
  77                   &Handle,
  78                   &gEfiMonotonicCounterArchProtocolGuid,    NULL,
  79                   NULL
  80                   );
  81   return Status;
  82 }