MdePkg/Library/BaseLib/X86DisablePaging64.c

   1 /** @file
   2   IA-32/x64 AsmDisablePaging64()
   3
   4   Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include "BaseLibInternals.h"
  10
  11 /**
  12   Disables the 64-bit paging mode on the CPU.
  13
  14   Disables the 64-bit paging mode on the CPU and returns to 32-bit protected
  15   mode. This function assumes the current execution mode is 64-paging mode.
  16   This function is only available on x64. After the 64-bit paging mode is
  17   disabled, control is transferred to the function specified by EntryPoint
  18   using the new stack specified by NewStack and passing in the parameters
  19   specified by Context1 and Context2. Context1 and Context2 are optional and
  20   may be 0. The function EntryPoint must never return.
  21
  22   If the current execution mode is not 64-bit paged mode, then ASSERT().
  23   If EntryPoint is 0, then ASSERT().
  24   If NewStack is 0, then ASSERT().
  25
  26   @param  Cs          The 16-bit selector to load in the CS before EntryPoint
  27                       is called. The descriptor in the GDT that this selector
  28                       references must be setup for 32-bit protected mode.
  29   @param  EntryPoint  The 64-bit virtual address of the function to call with
  30                       the new stack after paging is disabled.
  31   @param  Context1    The 64-bit virtual address of the context to pass into
  32                       the EntryPoint function as the first parameter after
  33                       paging is disabled.
  34   @param  Context2    The 64-bit virtual address of the context to pass into
  35                       the EntryPoint function as the second parameter after
  36                       paging is disabled.
  37   @param  NewStack    The 64-bit virtual address of the new stack to use for
  38                       the EntryPoint function after paging is disabled.
  39
  40 **/
  41 VOID
  42 EFIAPI
  43 AsmDisablePaging64 (
  44   IN      UINT16  Cs,
  45   IN      UINT32  EntryPoint,
  46   IN      UINT32  Context1   OPTIONAL,
  47   IN      UINT32  Context2   OPTIONAL,
  48   IN      UINT32  NewStack
  49   )
  50 {
  51   ASSERT (EntryPoint != 0);
  52   ASSERT (NewStack != 0);
  53   InternalX86DisablePaging64 (Cs, EntryPoint, Context1, Context2, NewStack);
  54 }