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