IntelFsp2Pkg/Library/SecFspSecPlatformLibNull/Ia32/Flat32.asm

   1 ;; @file
   2 ;  This is the code that goes from real-mode to protected mode.
   3 ;  It consumes the reset vector, configures the stack.
   4 ;
   5 ; Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
   6 ; This program and the accompanying materials
   7 ; are licensed and made available under the terms and conditions of the BSD License
   8 ; which accompanies this distribution.  The full text of the license may be found at
   9 ; http://opensource.org/licenses/bsd-license.php.
  10 ;
  11 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13 ;;
  14
  15 ;
  16 ; Define assembler characteristics
  17 ;
  18 .586p
  19 .xmm
  20 .model flat, c
  21
  22 EXTRN   TempRamInitApi:NEAR
  23
  24 .code
  25
  26 RET_ESI  MACRO
  27
  28   movd    esi, mm7                      ; restore ESP from MM7
  29   jmp     esi
  30
  31 ENDM
  32
  33 ;
  34 ; Perform early platform initialization
  35 ;
  36 SecPlatformInit    PROC    NEAR    PUBLIC
  37
  38   RET_ESI
  39
  40 SecPlatformInit    ENDP
  41
  42 ;
  43 ; Protected mode portion initializes stack, configures cache, and calls C entry point
  44 ;
  45
  46 ;----------------------------------------------------------------------------
  47 ;
  48 ; Procedure:    ProtectedModeEntryPoint
  49 ;
  50 ; Input:        Executing in 32 Bit Protected (flat) mode
  51 ;               cs: 0-4GB
  52 ;               ds: 0-4GB
  53 ;               es: 0-4GB
  54 ;               fs: 0-4GB
  55 ;               gs: 0-4GB
  56 ;               ss: 0-4GB
  57 ;
  58 ; Output:       This function never returns
  59 ;
  60 ; Destroys:
  61 ;               ecx
  62 ;               edi
  63 ;               esi
  64 ;               esp
  65 ;
  66 ; Description:
  67 ;               Perform any essential early platform initilaisation
  68 ;               Setup a stack
  69 ;
  70 ;----------------------------------------------------------------------------
  71
  72 ProtectedModeEntryPoint PROC NEAR C PUBLIC
  73   ;
  74   ; Dummy function. Consume 2 API to make sure they can be linked.
  75   ;
  76   mov  eax, TempRamInitApi
  77
  78   ; Should never return
  79   jmp  $
  80
  81 ProtectedModeEntryPoint ENDP
  82
  83 ;
  84 ; ROM-based Global-Descriptor Table for the PEI Phase
  85 ;
  86 align 16
  87 PUBLIC  BootGdtTable
  88
  89 ;
  90 ; GDT[0]: 0x00: Null entry, never used.
  91 ;
  92 NULL_SEL        equ     $ - GDT_BASE        ; Selector [0]
  93 GDT_BASE:
  94 BootGdtTable    DD      0
  95                 DD      0
  96 ;
  97 ; Linear code segment descriptor
  98 ;
  99 LINEAR_CODE_SEL equ     $ - GDT_BASE        ; Selector [0x8]
 100         DW      0FFFFh                      ; limit 0xFFFF
 101         DW      0                           ; base 0
 102         DB      0
 103         DB      09Bh                        ; present, ring 0, data, expand-up, not-writable
 104         DB      0CFh                        ; page-granular, 32-bit
 105         DB      0
 106 ;
 107 ; System data segment descriptor
 108 ;
 109 SYS_DATA_SEL    equ     $ - GDT_BASE        ; Selector [0x10]
 110         DW      0FFFFh                      ; limit 0xFFFF
 111         DW      0                           ; base 0
 112         DB      0
 113         DB      093h                        ; present, ring 0, data, expand-up, not-writable
 114         DB      0CFh                        ; page-granular, 32-bit
 115         DB      0
 116
 117 GDT_SIZE        EQU     $ - BootGDTtable    ; Size, in bytes
 118
 119 ;
 120 ; GDT Descriptor
 121 ;
 122 GdtDesc:                                    ; GDT descriptor
 123         DW      GDT_SIZE - 1                ; GDT limit
 124         DD      OFFSET BootGdtTable         ; GDT base address
 125
 126 ProtectedModeEntryLinearAddress   LABEL   FWORD
 127 ProtectedModeEntryLinearOffset    LABEL   DWORD
 128   DD      OFFSET ProtectedModeEntryPoint  ; Offset of our 32 bit code
 129   DW      LINEAR_CODE_SEL
 130
 131 END