UefiCpuPkg/ResetVector/Vtf0/Main.asm

   1 ;------------------------------------------------------------------------------
   2 ; @file
   3 ; Main routine of the pre-SEC code up through the jump into SEC
   4 ;
   5 ; Copyright (c) 2008 - 2009, 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
  17 BITS    16
  18
  19 ;
  20 ; Modified:  EBX, ECX, EDX, EBP
  21 ;
  22 ; @param[in,out]  RAX/EAX  Initial value of the EAX register
  23 ;                          (BIST: Built-in Self Test)
  24 ; @param[in,out]  DI       'BP': boot-strap processor, or
  25 ;                          'AP': application processor
  26 ; @param[out]     RBP/EBP  Address of Boot Firmware Volume (BFV)
  27 ; @param[out]     DS       Selector allowing flat access to all addresses
  28 ; @param[out]     ES       Selector allowing flat access to all addresses
  29 ; @param[out]     FS       Selector allowing flat access to all addresses
  30 ; @param[out]     GS       Selector allowing flat access to all addresses
  31 ; @param[out]     SS       Selector allowing flat access to all addresses
  32 ;
  33 ; @return         None  This routine jumps to SEC and does not return
  34 ;
  35 Main16:
  36     OneTimeCall EarlyInit16
  37
  38     ;
  39     ; Transition the processor from 16-bit real mode to 32-bit flat mode
  40     ;
  41     OneTimeCall TransitionFromReal16To32BitFlat
  42
  43 BITS    32
  44
  45     ;
  46     ; Search for the Boot Firmware Volume (BFV)
  47     ;
  48     OneTimeCall Flat32SearchForBfvBase
  49
  50     ;
  51     ; EBP - Start of BFV
  52     ;
  53
  54     ;
  55     ; Search for the SEC entry point
  56     ;
  57     OneTimeCall Flat32SearchForSecEntryPoint
  58
  59     ;
  60     ; ESI - SEC Core entry point
  61     ; EBP - Start of BFV
  62     ;
  63
  64 %ifdef ARCH_IA32
  65
  66     ;
  67     ; Restore initial EAX value into the EAX register
  68     ;
  69     mov     eax, esp
  70
  71     ;
  72     ; Jump to the 32-bit SEC entry point
  73     ;
  74     jmp     esi
  75
  76 %else
  77
  78     ;
  79     ; Transition the processor from 32-bit flat mode to 64-bit flat mode
  80     ;
  81     OneTimeCall Transition32FlatTo64Flat
  82
  83 BITS    64
  84
  85     ;
  86     ; Some values were calculated in 32-bit mode.  Make sure the upper
  87     ; 32-bits of 64-bit registers are zero for these values.
  88     ;
  89     mov     rax, 0x00000000ffffffff
  90     and     rsi, rax
  91     and     rbp, rax
  92     and     rsp, rax
  93
  94     ;
  95     ; RSI - SEC Core entry point
  96     ; RBP - Start of BFV
  97     ;
  98
  99     ;
 100     ; Restore initial EAX value into the RAX register
 101     ;
 102     mov     rax, rsp
 103
 104     ;
 105     ; Jump to the 64-bit SEC entry point
 106     ;
 107     jmp     rsi
 108
 109 %endif
 110
 111