1#------------------------------------------------------------------------------
2#
3# Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
4# 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      UINT32                    EntryPoint,
32#   IN      UINT32                    Context1,  OPTIONAL
33#   IN      UINT32                    Context2,  OPTIONAL
34#   IN      UINT32                    NewStack
35#   );
36#------------------------------------------------------------------------------
37
38ASM_GLOBAL ASM_PFX(InternalX86DisablePaging64)
39ASM_PFX(InternalX86DisablePaging64):
40    cli
41    lea    L1(%rip), %rsi                 # rsi <- The start address of transition code
42    mov    0x28(%rsp), %edi               # rdi <- New stack
43    lea    _mTransitionEnd(%rip), %rax    # rax <- end of transition code
44    sub    %rsi, %rax                     # rax <- The size of transition piece code
45    add    $4, %rax                       # round rax up to the next 4 byte boundary
46    and    $0xfc, %al
47    sub    %rax, %rdi                     # rdi <- use stack to hold transition code
48    mov    %edi, %r10d                    # r10 <- The start address of transicition code below 4G
49    push   %rcx                           # save rcx to stack
50    mov    %rax, %rcx                     # rcx <- The size of transition piece code
51    rep
52    movsb                                 # copy transition code to (new stack - 64byte) below 4G
53    pop    %rcx                           # restore rcx
54
55    mov    %r8d, %esi
56    mov    %r9d, %edi
57    mov    %r10d, %eax
58    sub    $4, %eax
59    push   %rcx                           # push Cs to stack
60    push   %r10                           # push address of transition code on stack
61    .byte  0x48, 0xcb                     # retq: Use far return to load CS register from stack
62                                          # (Use raw byte code since some GNU assemblers generates incorrect code for "retq")
63L1:
64    mov    %eax,%esp                      # set up new stack
65    mov    %cr0,%rax
66    btr    $0x1f,%eax                     # clear CR0.PG
67    mov    %rax,%cr0                      # disable paging
68
69    mov    %edx,%ebx                      # save EntryPoint to ebx, for rdmsr will overwrite edx
70    mov    $0xc0000080,%ecx
71    rdmsr
72    and    $0xfe,%ah                      # clear LME
73    wrmsr
74    mov    %cr4,%rax
75    and    $0xdf,%al                      # clear PAE
76    mov    %rax,%cr4
77    push   %rdi                           # push Context2
78    push   %rsi                           # push Context1
79    callq  *%rbx                          # transfer control to EntryPoint
80    jmp    .                              # no one should get here
81
82_mTransitionEnd :
83