EdkCompatibilityPkg/Foundation/Library/Thunk16/Ia32/Thunk16.S

   1 #*****************************************************************************
   2 #*
   3 #*   Copyright (c) 2006 - 2009, 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 #*    Thunk.asm
  15 #*
  16 #*   Abstract:
  17 #*
  18 #*    Real mode thunk
  19 #*
  20 #*****************************************************************************
  21 #include <EfiBind.h>
  22
  23     .686p:
  24
  25 .globl ASM_PFX(mCode16Size)
  26
  27 .data
  28 mCode16Size:    .long   _TEXT16SIZE
  29
  30 .data
  31
  32 NullSegSel:     .quad   0
  33 _16BitCsSel:
  34                 .word   -1
  35                 .word   0
  36                 .byte   0
  37                 .byte   0x9b
  38                 .byte   0x8f            # 16-bit segment
  39                 .byte   0
  40 _16BitSsSel:
  41                 .word   -1
  42                 .word   0
  43                 .byte   0
  44                 .byte   0x93
  45                 .byte   0x8f           # 16-bit segment
  46                 .byte   0
  47
  48 _16Gdtr:
  49                 .word      _16Gdtr - NullSegSel - 1
  50                 .long      NullSegSel
  51
  52
  53 .text
  54
  55
  56 ASM_PFX(Thunk16):
  57     push   %ebp
  58     push   %ebx
  59     push   %esi
  60     push   %edi
  61     push   %ds
  62     push   %es
  63     push   %fs
  64     push   %gs
  65     mov    0x24(%esp),%esi
  66     movzwl 0x32(%esi),%edx
  67     mov    0xc(%esi),%edi
  68     add    $0xffffffb0,%edi
  69     push   %edi                       #; save stack offset
  70     imul   $0x10,%edx,%eax            #; eax <- edx*16
  71     add    %eax,%edi                  #; edi <- linear address of 16-bit stack
  72     push   $0xd
  73     pop    %ecx
  74     rep movsl %ds:(%esi),%es:(%edi)   #; copy context to 16-bit stack
  75     pop    %ebx                       #; ebx <- 16-bit stack offset
  76     mov    $L_Lable1,%eax
  77     stos   %eax,%es:(%edi)
  78     movl   %cs,%eax
  79     stos   %ax,%es:(%edi)
  80     mov    0x28(%esp),%eax
  81     stos   %ax,%es:(%edi)
  82     mov    %esp,%eax
  83     stos   %eax,%es:(%edi)
  84     movl   %ss,%eax
  85     stos   %ax,%es:(%edi)
  86     sgdtl  (%edi)
  87     sidtl  0x24(%esp)
  88     mov    %cr0,%esi
  89     mov    %esi,0x6(%edi)             #; save CR0
  90     and    $0x7ffffffe,%esi           #; esi <- CR0 to set
  91     mov    %cr4,%eax
  92     mov    %eax,0xa(%edi)             #; save CR4
  93     and    $0xcf,%al                  #; clear PAE & PSE
  94     mov    %edx,%edi                  #; edi <- 16-bit stack segment
  95     mov    0x2c(%esp),%edx
  96     shl    $0x10,%edx
  97     push   %edx
  98     pop    %edx
  99     mov    $(_16BitSsSel - NullSegSel),%dx
 100     lgdtl  _16Gdtr                    #bugbug mismatch.
 101     .byte  0xea
 102     .long  L_16Bit                    #bugbug mismatch.
 103     .word  _16BitCsSel - NullSegSel
 104 L_16Bit:
 105     .byte  0x66
 106     movw   %dx,%ss
 107     mov    %esi,%cr0
 108     mov    %eax,%cr4
 109     .byte  0x67
 110     .byte  0xff
 111     .byte  0x6c
 112     .byte  0x24
 113     .byte  0xfc
 114
 115 L_Lable1:
 116     movl   %ss,%eax
 117     shl    $0x4,%eax
 118     add    %esp,%eax
 119     lss    0x3c(%esp),%esp
 120     lidtl  0x24(%esp)
 121     pop    %gs
 122     pop    %fs
 123     pop    %es
 124     pop    %ds
 125     pop    %edi
 126     pop    %esi
 127     pop    %ebx
 128     pop    %ebp
 129     ret
 130
 131 .code16
 132 _Code16Addr:
 133 ASM_PFX(RealMode):
 134     movw    %di, %ss                    # set up stack
 135     movl    %ebx, %esp
 136     lidt    %cs:_16Idtr - _Code16Addr  #lidt    fword ptr cs:[_16Idtr - _Code16Addr]
 137     .byte   0x66
 138     popaw
 139     popw    %ds
 140     popw    %es
 141     popw    %fs
 142     popw    %gs
 143     addw    $4, %sp                     # skip EFlags
 144     testw   $1, 14(%esp)                  #(_STK16 ptr [esp + 8]).ThunkFlags, 1
 145     jz      1f
 146     pushf
 147 1:
 148     pushw   %cs
 149 #    push    @FarCallRet - _Code16Addr
 150     .byte   0x68                        # push /iw
 151     .word   FarCallRet - _Code16Addr
 152     jz      2f
 153     ljmp    *6(%esp)                  #bugbug
 154 2:
 155     ljmp    *4(%esp)                  #bugbug
 156 FarCallRet:
 157     pushfl
 158     pushw   %gs
 159     pushw   %fs
 160     pushw   %es
 161     pushw   %ds
 162     pushal
 163     cli
 164     .byte   0x66                        # sizeof (IA32_REGS) = 13 * 4 = 52
 165     lgdt    66(%esp)                    #lgdt    (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedGdtr
 166     mov     76(%esp), %eax
 167     movl    %eax, %cr4
 168     mov     72(%esp), %eax
 169     movl    %eax, %cr0                   # restore CR0
 170     ljmpl   *52(%esp)
 171 #RealMode ENDP
 172
 173 .text
 174 _16Idtr:
 175     .word 0x3ff                         #_16Idtr     FWORD   (1 SHL 10) - 1
 176     .byte 0x00
 177
 178 _TEXT16END:
 179
 180 _TEXT16SIZE = _TEXT16END - _Code16Addr
 181
 182