MdePkg/Library/MmServicesTableLib/MmServicesTableLib.c

   1 /** @file
   2   MM Services Table Library.
   3
   4   Copyright (c) 2009 - 2018, Intel Corporation. All rights reserved.<BR>
   5   Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7
   8 **/
   9
  10 #include <PiMm.h>
  11 #include <Protocol/MmBase.h>
  12 #include <Library/MmServicesTableLib.h>
  13 #include <Library/DebugLib.h>
  14
  15 EFI_MM_SYSTEM_TABLE   *gMmst             = NULL;
  16
  17 /**
  18   The constructor function caches the pointer of the MM Services Table.
  19
  20   @param  ImageHandle   The firmware allocated handle for the EFI image.
  21   @param  SystemTable   A pointer to the EFI System Table.
  22
  23   @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
  24
  25 **/
  26 EFI_STATUS
  27 EFIAPI
  28 MmServicesTableLibConstructor (
  29   IN EFI_HANDLE        ImageHandle,
  30   IN EFI_SYSTEM_TABLE  *SystemTable
  31   )
  32 {
  33   EFI_STATUS              Status;
  34   EFI_MM_BASE_PROTOCOL    *InternalMmBase;
  35
  36   InternalMmBase = NULL;
  37   //
  38   // Retrieve MM Base Protocol,  Do not use gBS from UefiBootServicesTableLib on purpose
  39   // to prevent inclusion of gBS, gST, and gImageHandle from SMM Drivers unless the
  40   // MM driver explicity declares that dependency.
  41   //
  42   Status = SystemTable->BootServices->LocateProtocol (
  43                                         &gEfiMmBaseProtocolGuid,
  44                                         NULL,
  45                                         (VOID **)&InternalMmBase
  46                                         );
  47   ASSERT_EFI_ERROR (Status);
  48   ASSERT (InternalMmBase != NULL);
  49
  50   //
  51   // We are in MM, retrieve the pointer to MM System Table
  52   //
  53   InternalMmBase->GetMmstLocation (InternalMmBase, &gMmst);
  54   ASSERT (gMmst != NULL);
  55
  56   return EFI_SUCCESS;
  57 }