MdePkg/Library/BaseLib/X64/DisablePaging64.S

   1 #------------------------------------------------------------------------------
   2 #
   3 # Copyright (c) 2006 - 2008, Intel Corporation
   4 # All rights reserved. This program and the accompanying materials
   5 # are licensed and made available under the terms and conditions of the BSD License
   6 # which accompanies this distribution.  The full text of the license may be found at
   7 # http://opensource.org/licenses/bsd-license.php
   8 #
   9 # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 #
  12 # Module Name:
  13 #
  14 #   DisablePaging64.S
  15 #
  16 # Abstract:
  17 #
  18 #   AsmDisablePaging64 function
  19 #
  20 # Notes:
  21 #
  22 #------------------------------------------------------------------------------
  23
  24
  25
  26 #------------------------------------------------------------------------------
  27 # VOID
  28 # EFIAPI
  29 # InternalX86DisablePaging64 (
  30 #   IN      UINT16                    Cs,
  31 #   IN      UINT64                    EntryPoint,
  32 #   IN      UINT64                    Context1,  OPTIONAL
  33 #   IN      UINT32                    Context2,  OPTIONAL
  34 #   IN      UINT64                    NewStack
  35 #   );
  36 #------------------------------------------------------------------------------
  37
  38 .global ASM_PFX(InternalX86DisablePaging64)
  39 ASM_PFX(InternalX86DisablePaging64):
  40     cli
  41     shl    $0x20,%rcx                     # rcx[32..47] <- Cs
  42     lea    L1, %eax
  43     mov    %r8d, %esi
  44     or     %rax, %rcx                     # rcx[0..47] <- Cs:@F
  45     mov    %r9d, %edi
  46     mov    0x28(%rsp), %eax               # eax <- New Stack
  47     push   %rcx
  48     ret                                   # switch to compatibility mode
  49 L1:
  50     mov    %eax,%esp                      # set up new stack
  51     mov    %cr0,%rax
  52     btr    $0x1f,%eax
  53     mov    %rax,%cr0                      # disable paging
  54     mov    $0xc0000080,%ecx
  55     rdmsr
  56     and    $0xfe,%ah                      # clear LME
  57     wrmsr
  58     mov    %cr4,%rax
  59     and    $0xdf,%al                      # clear PAE
  60     mov    %rax,%cr4
  61     push   %rdi                           # push Context2
  62     push   %rsi                           # push Context1
  63     callq  *%rdx                          # transfer control to EntryPoint
  64     jmp    .                              # no one should get here
  65