UefiCpuPkg/CpuDxe/CpuMp.c

   1 /** @file
   2   CPU DXE Module.
   3
   4   Copyright (c) 2008 - 2014, 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 "CpuDxe.h"
  16 #include "CpuMp.h"
  17
  18 UINTN gMaxLogicalProcessorNumber;
  19 UINTN gApStackSize;
  20
  21 VOID *mCommonStack = 0;
  22 VOID *mTopOfApCommonStack = 0;
  23 VOID *mApStackStart = 0;
  24
  25 volatile UINTN mNumberOfProcessors;
  26
  27 /**
  28   Application Processor C code entry point.
  29
  30 **/
  31 VOID
  32 EFIAPI
  33 ApEntryPointInC (
  34   VOID
  35   )
  36 {
  37   mNumberOfProcessors++;
  38 }
  39
  40
  41 /**
  42   Initialize Multi-processor support.
  43
  44 **/
  45 VOID
  46 InitializeMpSupport (
  47   VOID
  48   )
  49 {
  50   gMaxLogicalProcessorNumber = (UINTN) PcdGet32 (PcdCpuMaxLogicalProcessorNumber);
  51   if (gMaxLogicalProcessorNumber < 1) {
  52     DEBUG ((DEBUG_ERROR, "Setting PcdCpuMaxLogicalProcessorNumber should be more than zero.\n"));
  53     return;
  54   }
  55
  56   if (gMaxLogicalProcessorNumber == 1) {
  57     return;
  58   }
  59
  60   gApStackSize = (UINTN) PcdGet32 (PcdCpuApStackSize);
  61   ASSERT ((gApStackSize & (SIZE_4KB - 1)) == 0);
  62
  63   mApStackStart = AllocatePages (EFI_SIZE_TO_PAGES (gMaxLogicalProcessorNumber * gApStackSize));
  64   ASSERT (mApStackStart != NULL);
  65
  66   //
  67   // the first buffer of stack size used for common stack, when the amount of AP
  68   // more than 1, we should never free the common stack which maybe used for AP reset.
  69   //
  70   mCommonStack = mApStackStart;
  71   mTopOfApCommonStack = (UINT8*) mApStackStart + gApStackSize;
  72   mApStackStart = mTopOfApCommonStack;
  73
  74   mNumberOfProcessors = 1;
  75
  76   if (mNumberOfProcessors == 1) {
  77     FreePages (mCommonStack, EFI_SIZE_TO_PAGES (gMaxLogicalProcessorNumber * gApStackSize));
  78     return;
  79   }
  80
  81   if (mNumberOfProcessors < gMaxLogicalProcessorNumber) {
  82     FreePages (mApStackStart, EFI_SIZE_TO_PAGES ((gMaxLogicalProcessorNumber - mNumberOfProcessors) *
  83                                                  gApStackSize));
  84   }
  85 }