;------------------------------------------------------------------------------ | |
; @file | |
; Search for the Boot Firmware Volume (BFV) base address | |
; | |
; Copyright (c) 2008 - 2009, Intel Corporation. All rights reserved.<BR> | |
; Copyright (c) 2019, Citrix Systems, Inc. | |
; | |
; SPDX-License-Identifier: BSD-2-Clause-Patent | |
; | |
;------------------------------------------------------------------------------ | |
;#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, ECX | |
; Preserved: EDI, ESP | |
; | |
; @param[in] EAX Start search from here | |
; @param[out] EBP Address of Boot Firmware Volume (BFV) | |
; | |
Flat32SearchForBfvBase: | |
mov ecx, eax | |
searchingForBfvHeaderLoop: | |
; | |
; We check for a firmware volume at every 4KB address in the 16MB | |
; just below where we started, ECX. | |
; | |
sub eax, 0x1000 | |
mov ebx, ecx | |
sub ebx, eax | |
cmp ebx, 0x01000000 | |
; if ECX-EAX > 16MB; jump notfound | |
ja 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] | |
cmp ebx, ecx | |
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 | |