;------------------------------------------------------------------------------ | |
; @file | |
; Search for the Boot Firmware Volume (BFV) base address | |
; | |
; Copyright (c) 2008 - 2009, Intel Corporation. All rights reserved.<BR> | |
; 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 | |