IntelFsp2Pkg/Library/SecFspSecPlatformLibNull/Ia32/Flat32.nasm

   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 - 2018, Intel Corporation. All rights reserved.<BR>
   6 ; SPDX-License-Identifier: BSD-2-Clause-Patent
   7 ;;
   8
   9 ;
  10 ; Define assembler characteristics
  11 ;
  12
  13 extern   ASM_PFX(TempRamInitApi)
  14
  15 SECTION .text
  16
  17 %macro RET_ESI  0
  18
  19   movd    esi, mm7                      ; restore ESP from MM7
  20   jmp     esi
  21
  22 %endmacro
  23
  24 ;
  25 ; Perform early platform initialization
  26 ;
  27 global ASM_PFX(SecPlatformInit)
  28 ASM_PFX(SecPlatformInit):
  29
  30   RET_ESI
  31
  32 ;
  33 ; Protected mode portion initializes stack, configures cache, and calls C entry point
  34 ;
  35
  36 ;----------------------------------------------------------------------------
  37 ;
  38 ; Procedure:    ProtectedModeEntryPoint
  39 ;
  40 ; Input:        Executing in 32 Bit Protected (flat) mode
  41 ;               cs: 0-4GB
  42 ;               ds: 0-4GB
  43 ;               es: 0-4GB
  44 ;               fs: 0-4GB
  45 ;               gs: 0-4GB
  46 ;               ss: 0-4GB
  47 ;
  48 ; Output:       This function never returns
  49 ;
  50 ; Destroys:
  51 ;               ecx
  52 ;               edi
  53 ;               esi
  54 ;               esp
  55 ;
  56 ; Description:
  57 ;               Perform any essential early platform initilaisation
  58 ;               Setup a stack
  59 ;
  60 ;----------------------------------------------------------------------------
  61 global ASM_PFX(ProtectedModeEntryPoint)
  62 ASM_PFX(ProtectedModeEntryPoint):
  63   ;
  64   ; Dummy function. Consume 2 API to make sure they can be linked.
  65   ;
  66   mov  eax, ASM_PFX(TempRamInitApi)
  67
  68   ; Should never return
  69   jmp  $
  70
  71 ;
  72 ; ROM-based Global-Descriptor Table for the PEI Phase
  73 ;
  74 align 16
  75 global  ASM_PFX(BootGdtTable)
  76
  77 ;
  78 ; GDT[0]: 0x00: Null entry, never used.
  79 ;
  80 NULL_SEL        equ     $ - GDT_BASE        ; Selector [0]
  81 GDT_BASE:
  82 ASM_PFX(BootGdtTable):    DD      0
  83                           DD      0
  84 ;
  85 ; Linear code segment descriptor
  86 ;
  87 LINEAR_CODE_SEL equ     $ - GDT_BASE        ; Selector [0x8]
  88         DW      0FFFFh                      ; limit 0xFFFF
  89         DW      0                           ; base 0
  90         DB      0
  91         DB      09Bh                        ; present, ring 0, data, expand-up, not-writable
  92         DB      0CFh                        ; page-granular, 32-bit
  93         DB      0
  94 ;
  95 ; System data segment descriptor
  96 ;
  97 SYS_DATA_SEL    equ     $ - GDT_BASE        ; Selector [0x10]
  98         DW      0FFFFh                      ; limit 0xFFFF
  99         DW      0                           ; base 0
 100         DB      0
 101         DB      093h                        ; present, ring 0, data, expand-up, not-writable
 102         DB      0CFh                        ; page-granular, 32-bit
 103         DB      0
 104
 105 GDT_SIZE        EQU     $ - GDT_BASE        ; Size, in bytes
 106
 107 ;
 108 ; GDT Descriptor
 109 ;
 110 GdtDesc:                                    ; GDT descriptor
 111         DW      GDT_SIZE - 1                ; GDT limit
 112         DD      GDT_BASE                    ; GDT base address
 113
 114 global ASM_PFX(ProtectedModeEntryLinearAddress)
 115 global ASM_PFX(ProtectedModeEntryLinearOffset)
 116
 117 ASM_PFX(ProtectedModeEntryLinearAddress):
 118 ASM_PFX(ProtectedModeEntryLinearOffset):
 119   DD      ASM_PFX(ProtectedModeEntryPoint)  ; Offset of our 32 bit code
 120   DW      LINEAR_CODE_SEL
 121