MdePkg/Library/SmmServicesTableLib/SmmServicesTableLib.c

   1 /** @file
   2   SMM Services Table Library.
   3
   4   Copyright (c) 2009 - 2010, 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 EFI_SMM_BASE2_PROTOCOL  *mInternalSmmBase2 = NULL;
  22
  23 /**
  24   The constructor function caches the pointer of SMM Services Table.
  25
  26   @param  ImageHandle   The firmware allocated handle for the EFI image.
  27   @param  SystemTable   A pointer to the EFI System Table.
  28
  29   @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
  30
  31 **/
  32 EFI_STATUS
  33 EFIAPI
  34 SmmServicesTableLibConstructor (
  35   IN EFI_HANDLE        ImageHandle,
  36   IN EFI_SYSTEM_TABLE  *SystemTable
  37   )
  38 {
  39   EFI_STATUS  Status;
  40
  41   //
  42   // Retrieve SMM Base2 Protocol,  Do not use gBS from UefiBootServicesTableLib on purpose
  43   // to prevent inclusion of gBS, gST, and gImageHandle from SMM Drivers unless the
  44   // SMM driver explicity declares that dependency.
  45   //
  46   Status = SystemTable->BootServices->LocateProtocol (
  47                                         &gEfiSmmBase2ProtocolGuid,
  48                                         NULL,
  49                                         (VOID **)&mInternalSmmBase2
  50                                         );
  51   ASSERT_EFI_ERROR (Status);
  52   ASSERT (mInternalSmmBase2 != NULL);
  53
  54   //
  55   // Check to see if we are already in SMM
  56   //
  57   if (!InSmm ()) {
  58     //
  59     // We are not in SMM, so SMST is not needed
  60     //
  61     return EFI_SUCCESS;
  62   }
  63
  64   //
  65   // We are in SMM, retrieve the pointer to SMM System Table
  66   //
  67   mInternalSmmBase2->GetSmstLocation (mInternalSmmBase2, &gSmst);
  68   ASSERT (gSmst != NULL);
  69
  70   return EFI_SUCCESS;
  71 }
  72
  73 /**
  74   This function allows the caller to determine if the driver is executing in
  75   System Management Mode(SMM).
  76
  77   This function returns TRUE if the driver is executing in SMM and FALSE if the
  78   driver is not executing in SMM.
  79
  80   @retval  TRUE  The driver is executing in System Management Mode (SMM).
  81   @retval  FALSE The driver is not executing in System Management Mode (SMM).
  82
  83 **/
  84 BOOLEAN
  85 EFIAPI
  86 InSmm (
  87   VOID
  88   )
  89 {
  90   BOOLEAN  InSmm;
  91
  92   //
  93   // Check to see if we are already in SMM
  94   //
  95   mInternalSmmBase2->InSmm (mInternalSmmBase2, &InSmm);
  96   return InSmm;
  97 }