MdePkg/Library/BaseLib/x86DisablePaging64.c

   1 /** @file
   2   IA-32/x64 AsmDisablePaging64()
   3
   4   Copyright (c) 2006, Intel Corporation<BR>
   5   All rights reserved. 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 //
  16 // Include common header file for this module.
  17 //
  18
  19
  20 #include "BaseLibInternals.h"
  21
  22 /**
  23   Disables the 64-bit paging mode on the CPU.
  24
  25   Disables the 64-bit paging mode on the CPU and returns to 32-bit protected
  26   mode. This function assumes the current execution mode is 64-paging mode.
  27   This function is only available on X64. After the 64-bit paging mode is
  28   disabled, control is transferred to the function specified by EntryPoint
  29   using the new stack specified by NewStack and passing in the parameters
  30   specified by Context1 and Context2. Context1 and Context2 are optional and
  31   may be 0. The function EntryPoint must never return.
  32
  33   If the current execution mode is not 64-bit paged mode, then ASSERT().
  34   If EntryPoint is 0, then ASSERT().
  35   If NewStack is 0, then ASSERT().
  36
  37   @param  Cs          The 16-bit selector to load in the CS before EntryPoint
  38                       is called. The descriptor in the GDT that this selector
  39                       references must be setup for 32-bit protected mode.
  40   @param  EntryPoint  The 64-bit virtual address of the function to call with
  41                       the new stack after paging is disabled.
  42   @param  Context1    The 64-bit virtual address of the context to pass into
  43                       the EntryPoint function as the first parameter after
  44                       paging is disabled.
  45   @param  Context2    The 64-bit virtual address of the context to pass into
  46                       the EntryPoint function as the second parameter after
  47                       paging is disabled.
  48   @param  NewStack    The 64-bit virtual address of the new stack to use for
  49                       the EntryPoint function after paging is disabled.
  50
  51 **/
  52 VOID
  53 EFIAPI
  54 AsmDisablePaging64 (
  55   IN      UINT16                    Cs,
  56   IN      UINT32                    EntryPoint,
  57   IN      UINT32                    Context1,  OPTIONAL
  58   IN      UINT32                    Context2,  OPTIONAL
  59   IN      UINT32                    NewStack
  60   )
  61 {
  62   ASSERT (EntryPoint != 0);
  63   ASSERT (NewStack != 0);
  64   InternalX86DisablePaging64 (Cs, EntryPoint, Context1, Context2, NewStack);
  65 }