1;------------------------------------------------------------------------------ 2; @file 3; Search for the Boot Firmware Volume (BFV) base address 4; 5; Copyright (c) 2008 - 2009, Intel Corporation. All rights reserved.<BR> 6; SPDX-License-Identifier: BSD-2-Clause-Patent 7; 8;------------------------------------------------------------------------------ 9 10;#define EFI_FIRMWARE_FILE_SYSTEM2_GUID \ 11; { 0x8c8ce578, 0x8a3d, 0x4f1c, { 0x99, 0x35, 0x89, 0x61, 0x85, 0xc3, 0x2d, 0xd3 } } 12%define FFS_GUID_DWORD0 0x8c8ce578 13%define FFS_GUID_DWORD1 0x4f1c8a3d 14%define FFS_GUID_DWORD2 0x61893599 15%define FFS_GUID_DWORD3 0xd32dc385 16 17BITS 32 18 19; 20; Modified: EAX, EBX 21; Preserved: EDI, ESP 22; 23; @param[out] EBP Address of Boot Firmware Volume (BFV) 24; 25Flat32SearchForBfvBase: 26 27 xor eax, eax 28searchingForBfvHeaderLoop: 29 ; 30 ; We check for a firmware volume at every 4KB address in the top 16MB 31 ; just below 4GB. (Addresses at 0xffHHH000 where H is any hex digit.) 32 ; 33 sub eax, 0x1000 34 cmp eax, 0xff000000 35 jb searchedForBfvHeaderButNotFound 36 37 ; 38 ; Check FFS GUID 39 ; 40 cmp dword [eax + 0x10], FFS_GUID_DWORD0 41 jne searchingForBfvHeaderLoop 42 cmp dword [eax + 0x14], FFS_GUID_DWORD1 43 jne searchingForBfvHeaderLoop 44 cmp dword [eax + 0x18], FFS_GUID_DWORD2 45 jne searchingForBfvHeaderLoop 46 cmp dword [eax + 0x1c], FFS_GUID_DWORD3 47 jne searchingForBfvHeaderLoop 48 49 ; 50 ; Check FV Length 51 ; 52 cmp dword [eax + 0x24], 0 53 jne searchingForBfvHeaderLoop 54 mov ebx, eax 55 add ebx, dword [eax + 0x20] 56 jnz searchingForBfvHeaderLoop 57 58 jmp searchedForBfvHeaderAndItWasFound 59 60searchedForBfvHeaderButNotFound: 61 ; 62 ; Hang if the SEC entry point was not found 63 ; 64 debugShowPostCode POSTCODE_BFV_NOT_FOUND 65 66 ; 67 ; 0xbfbfbfbf in the EAX & EBP registers helps signal what failed 68 ; for debugging purposes. 69 ; 70 mov eax, 0xBFBFBFBF 71 mov ebp, eax 72 jmp $ 73 74searchedForBfvHeaderAndItWasFound: 75 mov ebp, eax 76 77 debugShowPostCode POSTCODE_BFV_FOUND 78 79 OneTimeCallRet Flat32SearchForBfvBase 80 81