MdePkg/Library/SmmServicesTableLib/SmmServicesTableLib.c

   1 /** @file
   2   SMM Services Table Library.
   3
   4   Copyright (c) 2009 - 2018, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include <PiSmm.h>
  10 #include <Protocol/SmmBase2.h>
  11 #include <Library/SmmServicesTableLib.h>
  12 #include <Library/DebugLib.h>
  13
  14 EFI_SMM_SYSTEM_TABLE2   *gSmst             = NULL;
  15
  16 /**
  17   The constructor function caches the pointer of SMM Services Table.
  18
  19   @param  ImageHandle   The firmware allocated handle for the EFI image.
  20   @param  SystemTable   A pointer to the EFI System Table.
  21
  22   @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
  23
  24 **/
  25 EFI_STATUS
  26 EFIAPI
  27 SmmServicesTableLibConstructor (
  28   IN EFI_HANDLE        ImageHandle,
  29   IN EFI_SYSTEM_TABLE  *SystemTable
  30   )
  31 {
  32   EFI_STATUS              Status;
  33   EFI_SMM_BASE2_PROTOCOL  *InternalSmmBase2;
  34
  35   InternalSmmBase2 = NULL;
  36   //
  37   // Retrieve SMM Base2 Protocol,  Do not use gBS from UefiBootServicesTableLib on purpose
  38   // to prevent inclusion of gBS, gST, and gImageHandle from SMM Drivers unless the
  39   // SMM driver explicity declares that dependency.
  40   //
  41   Status = SystemTable->BootServices->LocateProtocol (
  42                                         &gEfiSmmBase2ProtocolGuid,
  43                                         NULL,
  44                                         (VOID **)&InternalSmmBase2
  45                                         );
  46   ASSERT_EFI_ERROR (Status);
  47   ASSERT (InternalSmmBase2 != NULL);
  48
  49   //
  50   // We are in SMM, retrieve the pointer to SMM System Table
  51   //
  52   InternalSmmBase2->GetSmstLocation (InternalSmmBase2, &gSmst);
  53   ASSERT (gSmst != NULL);
  54
  55   return EFI_SUCCESS;
  56 }
  57
  58 /**
  59   This function allows the caller to determine if the driver is executing in
  60   System Management Mode(SMM).
  61
  62   This function returns TRUE if the driver is executing in SMM and FALSE if the
  63   driver is not executing in SMM.
  64
  65   @retval  TRUE  The driver is executing in System Management Mode (SMM).
  66   @retval  FALSE The driver is not executing in System Management Mode (SMM).
  67
  68 **/
  69 BOOLEAN
  70 EFIAPI
  71 InSmm (
  72   VOID
  73   )
  74 {
  75   //
  76   // We are already in SMM
  77   //
  78   return TRUE;
  79 }