diff options
Diffstat (limited to 'OvmfPkg/ResetVector/Ia32/SearchForSecEntry.asm')
| -rw-r--r-- | OvmfPkg/ResetVector/Ia32/SearchForSecEntry.asm | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/OvmfPkg/ResetVector/Ia32/SearchForSecEntry.asm b/OvmfPkg/ResetVector/Ia32/SearchForSecEntry.asm new file mode 100644 index 0000000000..01d051918c --- /dev/null +++ b/OvmfPkg/ResetVector/Ia32/SearchForSecEntry.asm @@ -0,0 +1,196 @@ +;------------------------------------------------------------------------------
+; @file
+; Search for the SEC Core entry point
+;
+; Copyright (c) 2008 - 2009, Intel Corporation
+; All rights reserved. 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.
+;
+;------------------------------------------------------------------------------
+
+BITS 32
+
+%define EFI_FV_FILETYPE_SECURITY_CORE 0x03
+
+;
+; Modified: EAX, EBX, ECX, EDX
+; Preserved: EDI, EBP, ESP
+;
+; @param[in] EBP Address of Boot Firmware Volume (BFV)
+; @param[out] ESI SEC Core Entry Point Address
+;
+Flat32SearchForSecEntryPoint:
+
+ ;
+ ; Initialize EBP and ESI to 0
+ ;
+ xor ebx, ebx
+ mov esi, ebx
+
+ ;
+ ; Pass over the BFV header
+ ;
+ mov eax, ebp
+ mov bx, [ebp + 0x30]
+ add eax, ebx
+ jc secEntryPointWasNotFound
+
+ jmp searchingForFfsFileHeaderLoop
+
+moveForwardWhileSearchingForFfsFileHeaderLoop:
+ ;
+ ; Make forward progress in the search
+ ;
+ inc eax
+ jc secEntryPointWasNotFound
+
+searchingForFfsFileHeaderLoop:
+ test eax, eax
+ jz secEntryPointWasNotFound
+
+ ;
+ ; Ensure 8 byte alignment
+ ;
+ add eax, 7
+ jc secEntryPointWasNotFound
+ and al, 0xf8
+
+ ;
+ ; Look to see if there is an FFS file at eax
+ ;
+ mov bl, [eax + 0x17]
+ test bl, 0x20
+ jz moveForwardWhileSearchingForFfsFileHeaderLoop
+ mov ecx, [eax + 0x14]
+ and ecx, 0x00ffffff
+ or ecx, ecx
+ jz moveForwardWhileSearchingForFfsFileHeaderLoop
+ add ecx, eax
+ jz jumpSinceWeFoundTheLastFfsFile
+ jc moveForwardWhileSearchingForFfsFileHeaderLoop
+jumpSinceWeFoundTheLastFfsFile:
+
+ ;
+ ; There seems to be a valid file at eax
+ ;
+ cmp byte [eax + 0x12], EFI_FV_FILETYPE_SECURITY_CORE ; Check File Type
+ jne readyToTryFfsFileAtEcx
+
+fileTypeIsSecCore:
+ OneTimeCall GetEntryPointOfFfsFile
+ test eax, eax
+ jnz doneSeachingForSecEntryPoint
+
+readyToTryFfsFileAtEcx:
+ ;
+ ; Try the next FFS file at ECX
+ ;
+ mov eax, ecx
+ jmp searchingForFfsFileHeaderLoop
+
+secEntryPointWasNotFound:
+ xor eax, eax
+
+doneSeachingForSecEntryPoint:
+ mov esi, eax
+
+ test esi, esi
+ jnz secCoreEntryPointWasFound
+
+secCoreEntryPointWasNotFound:
+ ;
+ ; Hang if the SEC entry point was not found
+ ;
+ debugShowPostCode POSTCODE_SEC_NOT_FOUND
+ jz $
+
+secCoreEntryPointWasFound:
+ debugShowPostCode POSTCODE_SEC_FOUND
+
+ OneTimeCallRet Flat32SearchForSecEntryPoint
+
+%define EFI_SECTION_PE32 0x10
+
+;
+; Input:
+; EAX - Start of FFS file
+; ECX - End of FFS file
+;
+; Output:
+; EAX - Entry point of PE32 (or 0 if not found)
+;
+; Modified:
+; EBX
+;
+GetEntryPointOfFfsFile:
+ test eax, eax
+ jz getEntryPointOfFfsFileErrorReturn
+ add eax, 0x18 ; EAX = Start of section
+
+getEntryPointOfFfsFileLoopForSections:
+ cmp eax, ecx
+ jae getEntryPointOfFfsFileErrorReturn
+
+ cmp byte [eax + 3], EFI_SECTION_PE32
+ je getEntryPointOfFfsFileFoundPe32Section
+
+ ;
+ ; The section type was not PE32, so move to next section
+ ;
+ mov ebx, dword [eax]
+ and ebx, 0x00ffffff
+ add eax, ebx
+ jc getEntryPointOfFfsFileErrorReturn
+
+ ;
+ ; Ensure that FFS section is 32-bit aligned
+ ;
+ add eax, 3
+ jc getEntryPointOfFfsFileErrorReturn
+ and al, 0xfc
+ jmp getEntryPointOfFfsFileLoopForSections
+
+getEntryPointOfFfsFileFoundPe32Section:
+ add eax, 4 ; EAX = Start of PE32 image
+
+ mov ebx, eax
+ cmp word [eax], 'MZ'
+ jne thereIsNotAnMzSignature
+ movzx ebx, word [eax + 0x3c]
+ add ebx, eax
+thereIsNotAnMzSignature:
+
+ ; if (Hdr.Te->Signature == EFI_TE_IMAGE_HEADER_SIGNATURE)
+ cmp word [ebx], 'VZ'
+ jne thereIsNoVzSignature
+ ; *EntryPoint = (VOID *)((UINTN)Pe32Data +
+ ; (UINTN)(Hdr.Te->AddressOfEntryPoint & 0x0ffffffff) +
+ ; sizeof(EFI_TE_IMAGE_HEADER) - Hdr.Te->StrippedSize);
+ add eax, [ebx + 0x8]
+ add eax, 0x28
+ movzx ebx, word [ebx + 0x6]
+ sub eax, ebx
+ jmp getEntryPointOfFfsFileReturn
+
+thereIsNoVzSignature:
+
+ ; if (Hdr.Pe32->Signature == EFI_IMAGE_NT_SIGNATURE)
+ cmp dword [ebx], `PE\x00\x00`
+ jne getEntryPointOfFfsFileErrorReturn
+
+ ; *EntryPoint = (VOID *)((UINTN)Pe32Data +
+ ; (UINTN)(Hdr.Pe32->OptionalHeader.AddressOfEntryPoint & 0x0ffffffff));
+ add eax, [ebx + 0x4 + 0x14 + 0x10]
+ jmp getEntryPointOfFfsFileReturn
+
+getEntryPointOfFfsFileErrorReturn:
+ mov eax, 0
+
+getEntryPointOfFfsFileReturn:
+ OneTimeCallRet GetEntryPointOfFfsFile
+
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