MdePkg/Library/UefiPalLib/UefiPalLib.c

   1 /** @file
   2   PAL Library implementation retrieving the PAL Entry Point from the SAL System Table
   3   register in the EFI System Confguration Table.
   4
   5   Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
   6   This program and the accompanying materials are
   7   licensed and made available under the terms and conditions of
   8   the BSD License which accompanies this distribution.  The full
   9   text of the license may be found at
  10   http://opensource.org/licenses/bsd-license.php.
  11
  12   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  13   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  14
  15 **/
  16
  17 #include <PiDxe.h>
  18
  19 #include <IndustryStandard/Sal.h>
  20 #include <Library/UefiLib.h>
  21 #include <Library/BaseLib.h>
  22 #include <Library/DebugLib.h>
  23
  24 #include <Guid/SalSystemTable.h>
  25
  26 UINT64               mPalProcEntry;
  27
  28 /**
  29   Makes a PAL procedure call.
  30
  31   This is a wrapper function to make a PAL procedure call.  Based on the Index value,
  32   this API will make static or stacked PAL call. Architected procedures may be designated
  33   as required or optional.  If a PAL procedure is specified as optional, a unique return
  34   code of 0xFFFFFFFFFFFFFFFF is returned in the Status field of the PAL_CALL_RETURN structure.
  35   This indicates that the procedure is not present in this PAL implementation.  It is the
  36   caller's responsibility to check for this return code after calling any optional PAL
  37   procedure. No parameter checking is performed on the 4 input parameters, but there are
  38   some common rules that the caller should follow when making a PAL call.  Any address
  39   passed to PAL as buffers for return parameters must be 8-byte aligned.  Unaligned addresses
  40   may cause undefined results.  For those parameters defined as reserved or some fields
  41   defined as reserved must be zero filled or the invalid argument return value may be
  42   returned or undefined result may occur during the execution of the procedure.
  43   This function is only available on IPF.
  44
  45   @param Index  The PAL procedure Index number.
  46   @param Arg2   The 2nd parameter for PAL procedure calls.
  47   @param Arg3   The 3rd parameter for PAL procedure calls.
  48   @param Arg4   The 4th parameter for PAL procedure calls.
  49
  50   @return Structure returned from the PAL Call procedure, including the status and return value.
  51
  52 **/
  53 PAL_CALL_RETURN
  54 EFIAPI
  55 PalCall (
  56   IN UINT64                  Index,
  57   IN UINT64                  Arg2,
  58   IN UINT64                  Arg3,
  59   IN UINT64                  Arg4
  60   )
  61 {
  62   //
  63   // mPalProcEntry is initialized in library constructor as PAL entry.
  64   //
  65   return AsmPalCall (
  66            mPalProcEntry,
  67            Index,
  68            Arg2,
  69            Arg3,
  70            Arg4
  71            );
  72
  73 }
  74
  75 /**
  76   The constructor function of UEFI Pal Lib.
  77
  78   The constructor function looks up the SAL System Table in the EFI System Configuration
  79   Table. Once the SAL System Table is found, the PAL Entry Point in the SAL System Table
  80   will be derived and stored into a global variable for library usage.
  81   It will ASSERT() if the SAL System Table cannot be found or the data in the SAL System
  82   Table is not the valid data.
  83
  84   @param  ImageHandle   The firmware allocated handle for the EFI image.
  85   @param  SystemTable   A pointer to the EFI System Table.
  86
  87   @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
  88
  89 **/
  90 EFI_STATUS
  91 EFIAPI
  92 UefiPalLibConstructor (
  93   IN EFI_HANDLE        ImageHandle,
  94   IN EFI_SYSTEM_TABLE  *SystemTable
  95   )
  96 {
  97   EFI_STATUS                     Status;
  98   SAL_ST_ENTRY_POINT_DESCRIPTOR  *SalStEntryDes;
  99   SAL_SYSTEM_TABLE_HEADER        *SalSystemTable;
 100
 101   Status = EfiGetSystemConfigurationTable (
 102              &gEfiSalSystemTableGuid,
 103              (VOID **) &SalSystemTable
 104              );
 105   ASSERT_EFI_ERROR (Status);
 106   ASSERT (SalSystemTable != NULL);
 107
 108   //
 109   // Check the first entry of SAL System Table,
 110   // because the SAL entry is in ascending order with the entry type,
 111   // the type 0 entry should be the first if exist.
 112   //
 113   SalStEntryDes = (SAL_ST_ENTRY_POINT_DESCRIPTOR *)(SalSystemTable + 1);
 114
 115   //
 116   // Assure the SAL ENTRY Type is 0
 117   //
 118   ASSERT (SalStEntryDes->Type == EFI_SAL_ST_ENTRY_POINT);
 119
 120   mPalProcEntry = SalStEntryDes->PalProcEntry;
 121   //
 122   // Make sure the PalCallAddress has the valid value
 123   //
 124   ASSERT (mPalProcEntry != 0);
 125
 126   return EFI_SUCCESS;
 127 }