MdePkg/Library/SmmServicesTableLib/SmmServicesTableLib.c

   1 /** @file
   2   SMM Services Table Library.
   3
   4   Copyright (c) 2009 - 2015, Intel Corporation. All rights reserved.<BR>
   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 <PiSmm.h>
  16 #include <Protocol/SmmBase2.h>
  17 #include <Library/SmmServicesTableLib.h>
  18 #include <Library/DebugLib.h>
  19
  20 EFI_SMM_SYSTEM_TABLE2   *gSmst             = NULL;
  21
  22 /**
  23   The constructor function caches the pointer of SMM Services Table.
  24
  25   @param  ImageHandle   The firmware allocated handle for the EFI image.
  26   @param  SystemTable   A pointer to the EFI System Table.
  27
  28   @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
  29
  30 **/
  31 EFI_STATUS
  32 EFIAPI
  33 SmmServicesTableLibConstructor (
  34   IN EFI_HANDLE        ImageHandle,
  35   IN EFI_SYSTEM_TABLE  *SystemTable
  36   )
  37 {
  38   EFI_STATUS              Status;
  39   EFI_SMM_BASE2_PROTOCOL  *InternalSmmBase2;
  40
  41   InternalSmmBase2 = NULL;
  42   //
  43   // Retrieve SMM Base2 Protocol,  Do not use gBS from UefiBootServicesTableLib on purpose
  44   // to prevent inclusion of gBS, gST, and gImageHandle from SMM Drivers unless the
  45   // SMM driver explicity declares that dependency.
  46   //
  47   Status = SystemTable->BootServices->LocateProtocol (
  48                                         &gEfiSmmBase2ProtocolGuid,
  49                                         NULL,
  50                                         (VOID **)&InternalSmmBase2
  51                                         );
  52   ASSERT_EFI_ERROR (Status);
  53   ASSERT (InternalSmmBase2 != NULL);
  54
  55   //
  56   // We are in SMM, retrieve the pointer to SMM System Table
  57   //
  58   InternalSmmBase2->GetSmstLocation (InternalSmmBase2, &gSmst);
  59   ASSERT (gSmst != NULL);
  60
  61   return EFI_SUCCESS;
  62 }
  63
  64 /**
  65   This function allows the caller to determine if the driver is executing in
  66   System Management Mode(SMM).
  67
  68   This function returns TRUE if the driver is executing in SMM and FALSE if the
  69   driver is not executing in SMM.
  70
  71   @retval  TRUE  The driver is executing in System Management Mode (SMM).
  72   @retval  FALSE The driver is not executing in System Management Mode (SMM).
  73
  74 **/
  75 BOOLEAN
  76 EFIAPI
  77 InSmm (
  78   VOID
  79   )
  80 {
  81   //
  82   // We are already in SMM
  83   //
  84   return TRUE;
  85 }