InOsEmuPkg/Library/PeiCoreServicesTablePointerLib/PeiServicesTablePointer.c

   1 /** @file
   2   PEI Services Table Pointer Library for PEI Core.
   3
   4   This library is used for PEI Core which does executed from flash device directly but
   5   executed in memory. When the PEI Core does a Set of the PEI Service table pointer
   6   a PPI is reinstalled so that PEIMs can update the copy of the PEI Services table
   7   they have cached.
   8
   9   Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
  10   Portiions copyrigth (c) 2011, Apple Inc. All rights reserved.
  11   This program and the accompanying materials
  12   are licensed and made available under the terms and conditions of the BSD License
  13   which accompanies this distribution.  The full text of the license may be found at
  14   http://opensource.org/licenses/bsd-license.php.
  15
  16   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  17   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  18
  19 **/
  20
  21 #include <PiPei.h>
  22 #include <Library/PeiServicesTablePointerLib.h>
  23 #include <Library/DebugLib.h>
  24
  25 #include <Ppi/EmuPeiServicesTableUpdate.h>
  26
  27
  28 CONST EFI_PEI_SERVICES  **gPeiServices = NULL;
  29
  30 /**
  31   Caches a pointer PEI Services Table.
  32
  33   Caches the pointer to the PEI Services Table specified by PeiServicesTablePointer
  34   in a CPU specific manner as specified in the CPU binding section of the Platform Initialization
  35   Pre-EFI Initialization Core Interface Specification.
  36
  37   If PeiServicesTablePointer is NULL, then ASSERT().
  38
  39   @param    PeiServicesTablePointer   The address of PeiServices pointer.
  40 **/
  41 VOID
  42 EFIAPI
  43 SetPeiServicesTablePointer (
  44   IN CONST EFI_PEI_SERVICES **PeiServicesTablePointer
  45   )
  46 {
  47   EFI_STATUS              Status;
  48   EFI_PEI_PPI_DESCRIPTOR  *PpiDescriptor;
  49   VOID                    *NotUsed;
  50
  51   gPeiServices = PeiServicesTablePointer;
  52
  53   Status = (*PeiServicesTablePointer)->LocatePpi (
  54                                         PeiServicesTablePointer,
  55                                         &gEmuPeiServicesTableUpdatePpiGuid, // GUID
  56                                         0,                 // INSTANCE
  57                                         &PpiDescriptor,    // EFI_PEI_PPI_DESCRIPTOR
  58                                         &NotUsed           // PPI
  59                                         );
  60   if (!EFI_ERROR (Status)) {
  61     //
  62     // Standard PI Mechanism is to use negative offset from IDT.
  63     // We can't do that in the emulator, so we make up a constant location
  64     // that every one can use. The first try may fail as the PEI Core is still
  65     // initializing its self, but that is OK.
  66     //
  67
  68     // Reinstall PPI to consumers know to update PEI Services pointer
  69     Status = (*PeiServicesTablePointer)->ReInstallPpi (
  70                                             PeiServicesTablePointer,
  71                                             PpiDescriptor,
  72                                             PpiDescriptor
  73                                             );
  74
  75   }
  76
  77 }
  78
  79 /**
  80   Retrieves the cached value of the PEI Services Table pointer.
  81
  82   Returns the cached value of the PEI Services Table pointer in a CPU specific manner
  83   as specified in the CPU binding section of the Platform Initialization Pre-EFI
  84   Initialization Core Interface Specification.
  85
  86   If the cached PEI Services Table pointer is NULL, then ASSERT().
  87
  88   @return  The pointer to PeiServices.
  89
  90 **/
  91 CONST EFI_PEI_SERVICES **
  92 EFIAPI
  93 GetPeiServicesTablePointer (
  94   VOID
  95   )
  96 {
  97   ASSERT (gPeiServices != NULL);
  98   ASSERT (*gPeiServices != NULL);
  99   return gPeiServices;
 100 }
 101
 102