diff options
| author |   Angelos Mouzakitis <a.mouzakitis@virtualopensystems.com> | 2023-10-10 14:33:42 +0000 |
|---|---|---|
| committer | Angelos Mouzakitis <a.mouzakitis@virtualopensystems.com> | 2023-10-10 14:33:42 +0000 |
| commit | af1a266670d040d2f4083ff309d732d648afba2a (patch) | |
| tree | 2fc46203448ddcc6f81546d379abfaeb323575e9 /roms/edk2/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm | |
| parent | e02cda008591317b1625707ff8e115a4841aa889 (diff) | |
Change-Id: Iaf8d18082d3991dec7c0ebbea540f092188eb4ec
Diffstat (limited to 'roms/edk2/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm')
| -rw-r--r-- | roms/edk2/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/roms/edk2/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm b/roms/edk2/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm new file mode 100644 index 000000000..190389c46 --- /dev/null +++ b/roms/edk2/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm @@ -0,0 +1,87 @@ +;------------------------------------------------------------------------------
+; @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
+
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