433 lines
19 KiB
Plaintext
433 lines
19 KiB
Plaintext
# SPDX-FileCopyrightText: 2022 Andrius Štikonas <andrius@stikonas.eu>
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# SPDX-FileCopyrightText: 2022 Jeremiah Orians <jeremiah@pdp10.guru>
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#
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# SPDX-License-Identifier: GPL-3.0-or-later
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# Usage: hex0 file.hex0 file
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# Does not validate the arguments or check for success
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# Calling convention:
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# First four arguments are passed via registers rcx, rdx, r8, r9 (if they fit in 64-bits)
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# but we need to leave stack space
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# rax, rcx, rdx, r8, r9, r10 and r11 are volatile and can be changed by called function
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# Stack must be 16-byte aligned before UEFI calls.
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# DOS MZ header
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4D 5A # Signature
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00 00 # Number of bytes in the last page.
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00 00 # Number of whole/partial pages
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00 00 # Number of entries in the relocation table.
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00 00 # Header size
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00 00 # Minimum allocation
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00 00 # Maximum allocation
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00 00 # Relocatable segment address for SS
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00 00 # Initial value for SP
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00 00 # Checksum (I don't think is looked at)
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00 00 # Initial value for IP (Seems ignored)
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00 00 # Relocatable segment address for CS (Seems ignored)
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00 00 # The (absolute) offset to the relocation table.
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00 00 # Value used for overlay management. If zero, this is the main executable
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00 00 00 00 00 00 00 00 # Reserved in PE
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00 00 # OEM identifier
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00 00 # OEM info
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00 00 00 00 00 00 00 00 00 00 # The required reserved 20 bytes of NULLS
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00 00 00 00 00 00 00 00 00 00
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40 00 00 00 # Starting address of the PE header
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# [0x40]
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# PE header
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50 45 00 00 # Signature "PE"
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64 86 # Machine
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01 00 # number of sections
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00 00 00 00 # Timestamp supposedly
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00 00 00 00 # PointerToSymbolTable
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00 00 00 00 # number of symbols
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F0 00 # SizeOfOptionalHeader
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00 00 # 'Characteristics'
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# [0x58]
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# COFF header bits
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0B 02 # Magic PE32+ (64 bit)
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00 00 # Linker version
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00 00 00 00 # size of code
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00 00 00 00 # sizeOfInitializedData
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00 00 00 00 # SizeOfUninitializedData
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00 10 00 00 # AddressOfEntryPoint
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00 00 00 00 # BaseOfCode
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00 00 00 00 00 00 00 00 # ImageBase
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01 00 00 00 # SectionAlignment
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01 00 00 00 # FileAlignment
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00 00 00 00 # OperatingSystemVersion
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00 00 00 00 # ImageVersion
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00 00 00 00 # SubsystemVersion
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00 00 00 00 # Win32VersionValue
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00 20 00 00 # SizeOfImage
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70 01 00 00 # SizeOfHeaders
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00 00 00 00 # CheckSum (isn't used at all)
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0A 00 # Subsystem
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00 00 # DllCharacteristics
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00 00 00 00 # SizeOfStackReserve
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00 00 00 00 # SizeOfStackCommit
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00 00 00 00 # SizeOfHeapReserve
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00 00 00 00 # SizeOfHeapCommit
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00 00 00 00 # LoaderFlags
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00 00 00 00 # NumberOfRvaAndSizes
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# [0xB8]
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# Data directories (has to be 16 entries always 16bytes per entry)
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00 00 00 00 # Export Table
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00 00 00 00 # Size of Export Table
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00 00 00 00 # Import Table
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10 00 00 00 # Size of Import Table
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00 00 00 00 # Resource Table
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00 00 00 00 # Size of Resource Table
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00 00 00 00 # Exception Table
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00 00 00 00 # Size of Exception Table
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00 00 00 00 # Certificate Table
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00 00 00 00 # Size of Certificate Table
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00 00 00 00 # Base Relocation Table
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00 00 00 00 # Size of Base Relocation Table
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00 00 00 00 # Debug Table
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00 00 00 00 # Size of Debug Table
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00 00 00 00 # Architecture Data Table
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00 00 00 00 # Size of Architecture Data Table
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00 00 00 00 # Global Pointer
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00 00 00 00 # NULL
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00 00 00 00 # TLS Table
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00 00 00 00 # Size of TLS Table
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00 00 00 00 # Load Config Table
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00 00 00 00 # Size of Load Config Table
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00 00 00 00 # Bound Import Table
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00 00 00 00 # Size of Bound Import Table
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00 00 00 00 # Import Address Table
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00 00 00 00 # Size of Import Address Table
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00 00 00 00 # Delay Import Descriptor Table
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00 00 00 00 # Size of Delay Import Descriptor Table
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00 00 00 00 # CLR Runtime header table
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00 00 00 00 # Size of CLR Runtime Header table
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00 00 00 00 00 00 00 00 # MUST BE NULL
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# no idea what it is yet
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00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00
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# [0x148]
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# Start of section headers
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00 00 00 00 00 00 00 00 ; Name of the section (empty) but could set to ".text"
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EF 01 00 00 ; VirtualSize
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00 10 00 00 ; VirtualAddress
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EF 01 00 00 ; SizeOfRawData
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70 01 00 00 ; PointerToRawData
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00 00 00 00 ; PointerToRelocations
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00 00 00 00 ; PointerToLinenumbers
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00 00 ; NumberOfRelocations
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00 00 ; NumberOfLinenumbers
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00 00 00 00 ; 'Characteristics'
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# [0x170]
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# Our actual program
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# efi_main(void *image_handle, struct efi_system_table *system)
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# :_start
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# Save non-volatile registers
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55 ; push_rbp
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53 ; push_rbx
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57 ; push_rdi
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56 ; push_rsi
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4154 ; push_r12
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4155 ; push_r13
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4156 ; push_r14
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4157 ; push_r15
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4989CF ; mov_r15,rcx # save image_handle
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4C8B72 60 ; mov_r14,[rdx+BYTE] !96 # system->boot
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# Open Loaded Image protocol
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4D89F9 ; mov_r9,r15 # arg4 = image_handle
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488D15 B2010000 ; lea_rdx,[rip+DWORD] %LOADED_IMAGE_PROTOCOL # guid = &LOADED_IMAGE_PROTOCOL
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4C89C9 ; mov_rcx,r9 # arg1 = image_handle
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50 ; push_rax # allocate stack for image
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4989E0 ; mov_r8,rsp # arg3 = &image
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6A 01 ; push !1 # arg6 = EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL
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6A 00 ; push !0 # arg5 = NULL
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4883EC 20 ; sub_rsp, !32 # allocate shadow stack space for UEFI function
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41FF96 18010000 ; call_[r14+DWORD] %280 # system->boot->open_protocol(image_handle, &guid, &image, image_handle, 0, EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL)
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4883C4 30 ; add_rsp, !48 # deallocate stack
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5F ; pop_rdi # get image
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# Get root file system
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4D89F9 ; mov_r9,r15 # arg4 = image_handle
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488D15 9D010000 ; lea_rdx,[rip+DWORD] %SIMPLE_FS_PROTOCOL # guid = &SIMPLE_FS_PROTOCOL
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488B4F 18 ; mov_rcx,[rdi+BYTE] !24 # arg1 = root_device = image->device
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4989CD ; mov_r13,rcx # save root_device
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50 ; push_rax # allocate stack for rootfs
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4989E0 ; mov_r8,rsp # arg3 = &rootfs
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6A 01 ; push !1 # arg6 = EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL
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6A 00 ; push !0 # arg5 = NULL
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4883EC 20 ; sub_rsp, !32 # allocate shadow stack space for UEFI function
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41FF96 18010000 ; call_[r14+DWORD] %280 # system->boot->open_protocol(root_device, &guid, &rootfs, image_handle, 0, EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL)
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4883C4 30 ; add_rsp, !48 # deallocate stack
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59 ; pop rcx # get rootfs
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# Get root directory
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50 ; push_rax # allocate stack for rootdir
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4889E2 ; mov_rdx,rsp # arg2 = &rootdir
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4883EC 20 ; sub_rsp, !32 # allocate shadow stack space for UEFI function
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FF51 08 ; call_[rcx+BYTE] !8 # rootfs->open_volume(rootfs, &rootdir)
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4883C4 20 ; add_rsp, !32 # deallocate stack
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5E ; pop_rsi # save rootdir
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# Push command line arguments onto stack
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488B5F 38 ; mov_rbx,[rdi+BYTE] !56 # options = image->load_options
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4889DA ; mov_rdx,rbx # save beginning of load_options
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48035F 30 ; add_rbx,[rdi+BYTE] !48 # go to the end of load_options
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# :loop_options [_start + 0x7C]
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4839D3 ; cmp_rbx,rdx # Check if we are done
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74 14 ; je !loop_options_done # We are done
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4883EB 02 ; sub_rbx, !2 # --options
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8A03 ; mov_al,[rbx] # *options
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3C 20 ; cmp_al, !0x20 # if *options != ' '
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75 F1 ; jne !loop_options # then continue looping
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C603 00 ; mov_[rbx], !0 # zero it
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4883C3 02 ; add_rbx, !2 # ++options
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53 ; push_rbx # push another argument onto stack
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EB E7 ; jmp !loop_options # next argument
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# :loop_options_done [_start + 0x95]
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# Open file for reading
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4158 ; pop_r8 # arg3 = in
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4883E4 F0 ; and_rsp, !-16 # align stack to 16 bytes
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52 ; push_rdx # allocate stack for fin
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4889E2 ; mov_rdx,rsp # arg2 = &fin
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6A 01 ; push !1 # arg5 = EFI_FILE_READ_ONLY
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6A 01 ; push !1 # prepare to set arg4 to EFI_FILE_MODE_READ
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4159 ; pop_r9 # arg4 = EFI_FILE_MODE_READ
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4889F1 ; mov_rcx,rsi # arg1 = rootdir
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4883EC 20 ; sub_rsp, !32 # allocate shadow stack space for UEFI function
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FF51 08 ; call_[rcx+BYTE] !8 # rootdir->open()
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4883C4 28 ; add_rsp, !40 # deallocate stack
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415C ; pop_r12 # get fin
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# Open file for writing
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4158 ; pop_r8 # arg3 = out
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4155 ; push_r13 # save root_device
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52 ; push_rdx # allocate stack for fout
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4889E2 ; mov_rdx,rsp # arg2 = &fout
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6A 00 ; push !0 # arg5 = 0
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6A 07 ; push !7 # to get 0x8000000000000003 we set the rightmost 3 bits
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4159 ; pop_r9 # and then do right rotation by 1
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49D1C9 ; ror_r9 # arg4 = EFI_FILE_MODE_CREATE| EFI_FILE_MODE_WRITE | EFI_FILE_MODE_READ
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4889F1 ; mov_rcx,rsi # arg1 = rootdir
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4883EC 20 ; sub_rsp, !32 # allocate shadow stack space for UEFI function
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FF51 08 ; call_[rcx+BYTE] !8 # rootdir->open()
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4883C4 28 ; add_rsp, !40 # deallocate stack
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415D ; pop_r13 # get fout
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# Save variables that are needed for cleanup
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4156 ; push_r14 # save system->boot
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56 ; push_rsi # save rootdir
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# Our flag for byte processing
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6A FF ; push !-1
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5B ; pop_rbx # rbx = -1
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# temp storage for the sum
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31FF ; xor_edi,edi # rdi = 0
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# :loop [_start+0xDE]
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# Read a byte
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E8 72000000 ; call %read_byte
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# process byte
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E8 1C000000 ; call %hex
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# deal with -1 values
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85C0 ; test_eax,eax
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7C F2 ; jl !loop
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# deal with toggle
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85DB ; test_ebx,ebx # jump if ebx >= 0
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7D 06 ; jge !print
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# process first byte of pair
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89C7 ; mov_edi,eax
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31DB ; xor_ebx,ebx # rbx = 0
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EB E8 ; jmp !loop
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# process second byte of pair
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# :print [_start+0xF6]
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# update the sum and store in output
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C1E7 04 ; shl_edi, !4
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01F8 ; add_eax,edi
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# flip the toggle
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FFCB ; dec_ebx # rbx = -1
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E8 3B000000 ; call %write_byte
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EB DA ; jmp !loop
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# :hex [_start+0x104]
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# Purge Comment Lines (#)
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3C 23 ; cmp_al, !35
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74 1E ; je !purge_comment
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# Purge Comment Lines (;)
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3C 3B ; cmp_al, !59
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74 1A ; je !purge_comment
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# deal all ascii less than '0'
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3C 30 ; cmp_al, !48
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7C 21 ; jl !ascii_other
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# deal with 0-9
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3C 3A ; cmp_al, !58
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7C 21 ; jl !ascii_num
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# deal with all ascii less than 'A'
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3C 41 ; cmp_al, !65
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7C 19 ; jl !ascii_other
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# deal with 'A'-'F'
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3C 47 ; cmp_al, !71
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7C 1E ; jl !ascii_high
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# deal with all ascii less than 'a'
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3C 61 ; cmp_al, !97
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7C 11 ; jl !ascii_other
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#deal with 'a'-'f'
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3C 67 ; cmp_al, !103
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7C 14 ; jl !ascii_low
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# The rest that remains needs to be ignored
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EB 0B ; jmp !ascii_other
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# :purge_comment [_start+0x126]
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53 ; push_rbx # align stack to 16 bytes
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E8 29000000 ; call %read_byte # Read a byte
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5B ; pop_rbx # deallocate stack
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# Loop if not LF
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3C 0A ; cmp_al, !10
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75 F5 ; jne !purge_comment
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# Otherwise return -1
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# :ascii_other [_start+0x131]
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6A FF ; push !-1
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58 ; pop_rax # return = -1
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C3 ; ret
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# :ascii_num [_start+0x135]
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2C 30 ; sub_al, !48
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C3 ; ret
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# :ascii_low [_start+0x138]
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2C 20 ; sub_al, !32 # convert to uppercase
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# :ascii_high [_start+0x13A]
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2C 37 ; sub_al, !55
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C3 ; ret
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# Writes byte stored in al
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# :write_byte [_start+0x13D]
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4C89E9 ; mov_rcx,r13 # arg1 = fout
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6A 01 ; push !1 # size = 1
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4889E2 ; mov_rdx,rsp # arg2 = &size
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50 ; push_rax # allocate stack
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4989E0 ; mov_r8,rsp # arg3 = &output
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4883EC 28 ; sub_rsp, !40 # allocate shadow stack space for UEFI function
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FF51 28 ; call_[rcx+BYTE] !40 # fout->write()
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4883C4 38 ; add_rsp, !56 # deallocate stack
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C3 ; ret # return
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# :read_byte [_start+0x155]
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4C89E1 ; mov_rcx,r12 # arg1 = fin
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6A 01 ; push !1 # size = 1
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4889E2 ; mov_rdx,rsp # arg2 = &size
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6A 00 ; push_rsi # allocate stack
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4989E0 ; mov_r8,rsp # arg3 = &input
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4883EC 28 ; sub_rsp, !40 # allocate shadow stack space for UEFI function
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FF51 20 ; call_[rcx+BYTE] !32 # fin->read()
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4883C4 28 ; add_rsp, !40 # deallocate stack
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58 ; pop_rax # save input to rax
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5E ; pop_rsi # save size to rsi
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# If the file ended (0 bytes read) terminate
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85F6 ; test_esi,esi # if size = 0
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74 01 ; je !terminate # then we are done
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C3 ; ret # return
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# :terminate [_start+0x174]
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58 ; pop_rax # deallocate stack (return code of read_byte)
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5E ; pop_rsi # restore rootdir
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415E ; pop_r14 # restore system->boot
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5B ; pop_rbx # restore root_device
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53 ; push_rbx # allocate stack
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4C89E1 ; mov_rcx,r12 # arg1 = fin
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FF51 10 ; call_[rcx+BYTE] !16 # fin->close()
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4C89E9 ; mov_rcx,r13 # arg1 = fout
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FF51 10 ; call_[rcx+BYTE] !16 # fout->close()
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4889F1 ; mov_rcx,rsi # arg1 = rootdir
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FF51 10 ; call_[rcx+BYTE] !16 # rootdir->close()
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4D89F8 ; mov_r8,r15 # arg3 = image_handle
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488D15 49000000 ; lea_rdx,[rip+DWORD] %SIMPLE_FS_PROTOCOL # guid = &SIMPLE_FS_PROTOCOL
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4889D9 ; mov_rcx,rbx # arg1 = root_device
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4D31C9 ; xor_r9,r9 # arg4 = NULL
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4883EC 20 ; sub_rsp, !32 # allocate shadow stack space for UEFI function
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41FF96 20010000 ; call_[r14+DWORD] %288 # system->boot->close_protocol(root_device, &guid, image_handle, 0)
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4D89F8 ; mov_r8,r15 # arg3 = image_handle
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488D15 1E000000 ; lea_rdx,[rip+DWORD] %LOADED_IMAGE_PROTOCOL # guid = &LOADED_IMAGE_PROTOCOL
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4C89C1 ; mov_rcx,r8 # arg1 = image_handle
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4D31C9 ; xor_r9,r9 # arg4 = NULL
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41FF96 20010000 ; call_[r14+DWORD] %288 # system->boot->close_protocol(image_handle, &guid, image_handle, 0)
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4883C4 28 ; add_rsp, !40 # deallocate stack
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# Restore non-volatile registers
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415F ; pop_r15
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415E ; pop_r14
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415D ; pop_r13
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415C ; pop_r12
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5E ; pop_rsi
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5F ; pop_rdi
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5B ; pop_rbx
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5D ; pop_rbp
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C3 ; ret # return to UEFI
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# Protocol GUIDs
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# :LOADED_IMAGE_PROTOCOL [_start+0x1CF]
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A1 31 1B 5B ; %0x5b1b31a1
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62 95 ; $0x9562
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D2 11 ; $0x11d2
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8E 3F 00 A0 C9 69 72 3B ; !0x8e !0x3f !0 !0xa0 !0xc9 !0x69 !0x72 !0x3b
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# :SIMPLE_FS_PROTOCOL [_start+0x1DF]
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22 5B 4E 96 ; %0x964e5b22
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59 64 ; $0x6459
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D2 11 ; $0x11d2
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8E 39 00 A0 C9 69 72 3B ; !0x8e !0x39 !0 !0xa0 !0xc9 !0x69 !0x72 !0x3b
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# :ELF_end [_start+0x1EF]
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