1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
|
;------------------------------------------------------------------------------
; @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
|
