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|
;------------------------------------------------------------------------------
; @file
; Search for the Boot Firmware Volume (BFV) base address
;
; Copyright (c) 2008 - 2009, Intel Corporation
; All rights reserved. This program and the accompanying materials
; are licensed and made available under the terms and conditions of the BSD License
; which accompanies this distribution. The full text of the license may be found at
; http://opensource.org/licenses/bsd-license.php
;
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
;
;------------------------------------------------------------------------------
;#define EFI_FIRMWARE_FILE_SYSTEM2_GUID \
; { 0x8c8ce578, 0x8a3d, 0x4f1c, { 0x99, 0x35, 0x89, 0x61, 0x85, 0xc3, 0x2d, 0xd3 } }
%define FFS_GUID_DWORD0 0x8c8ce578
%define FFS_GUID_DWORD1 0x4f1c8a3d
%define FFS_GUID_DWORD2 0x61893599
%define FFS_GUID_DWORD3 0xd32dc385
BITS 32
;
; Modified: EAX, EBX
; Preserved: EDI, ESP
;
; @param[out] EBP Address of Boot Firmware Volume (BFV)
;
Flat32SearchForBfvBase:
xor eax, eax
searchingForBfvHeaderLoop:
;
; We check for a firmware volume at every 4KB address in the top 16MB
; just below 4GB. (Addresses at 0xffHHH000 where H is any hex digit.)
;
sub eax, 0x1000
cmp eax, 0xff000000
jb searchedForBfvHeaderButNotFound
;
; Check FFS GUID
;
cmp dword [eax + 0x10], FFS_GUID_DWORD0
jne searchingForBfvHeaderLoop
cmp dword [eax + 0x14], FFS_GUID_DWORD1
jne searchingForBfvHeaderLoop
cmp dword [eax + 0x18], FFS_GUID_DWORD2
jne searchingForBfvHeaderLoop
cmp dword [eax + 0x1c], FFS_GUID_DWORD3
jne searchingForBfvHeaderLoop
;
; Check FV Length
;
cmp dword [eax + 0x24], 0
jne searchingForBfvHeaderLoop
mov ebx, eax
add ebx, dword [eax + 0x20]
jnz searchingForBfvHeaderLoop
jmp searchedForBfvHeaderAndItWasFound
searchedForBfvHeaderButNotFound:
;
; Hang if the SEC entry point was not found
;
debugShowPostCode POSTCODE_BFV_NOT_FOUND
;
; 0xbfbfbfbf in the EAX & EBP registers helps signal what failed
; for debugging purposes.
;
mov eax, 0xBFBFBFBF
mov ebp, eax
jmp $
searchedForBfvHeaderAndItWasFound:
mov ebp, eax
debugShowPostCode POSTCODE_BFV_FOUND
OneTimeCallRet Flat32SearchForBfvBase
|
