293 lines
14 KiB
Plaintext
293 lines
14 KiB
Plaintext
# SPDX-FileCopyrightText: 2022 Andrius Štikonas <andrius@stikonas.eu>
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# SPDX-FileCopyrightText: 2017 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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# efi_main(void *image_handle, struct efi_system_table *system)
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:_start
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4889E5 ; mov_rbp,rsp # save stack pointer
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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 %LOADED_IMAGE_PROTOCOL ; 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 %SIMPLE_FS_PROTOCOL ; 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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50 ; push_rax # allocate shadow stack space for UEFI function
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50 ; push_rax # 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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58 ; pop_rax # deallocate stack
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58 ; pop_rax # 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
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4839D3 ; cmp_rbx,rdx # Check if we are done
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74 !loop_options_done ; 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 !loop_options ; 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 !loop_options ; jmp !loop_options # next argument
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:loop_options_done
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# Open file for reading
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4158 ; pop_r8 # arg3 = in
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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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4157 ; push_r15 # save image_handle
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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
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# Read a byte
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E8 %read_byte ; call %read_byte
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# process byte
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E8 %hex ; call %hex
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# deal with -1 values
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85C0 ; test_eax,eax
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7C !loop ; 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 !print ; 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 !loop ; jmp !loop
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# process second byte of pair
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:print
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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 %write_byte ; call %write_byte
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EB !loop ; jmp !loop
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:hex
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# Purge Comment Lines (#)
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3C 23 ; cmp_al, !35
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74 !purge_comment ; je !purge_comment
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# Purge Comment Lines (;)
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3C 3B ; cmp_al, !59
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74 !purge_comment ; 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 !ascii_other ; 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 !ascii_num ; 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 !ascii_other ; 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 !ascii_high ; 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 !ascii_other ; 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 !ascii_low ; jl !ascii_low
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# The rest that remains needs to be ignored
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EB !ascii_other ; jmp !ascii_other
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:purge_comment
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# Read a byte
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E8 %read_byte ; call %read_byte
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# Loop if not LF
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3C 0A ; cmp_al, !10
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75 !purge_comment ; jne !purge_comment
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# Otherwise return -1
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:ascii_other
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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
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2C 30 ; sub_al, !48
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C3 ; ret
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:ascii_low
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2C 20 ; sub_al, !32 # convert to uppercase
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:ascii_high
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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
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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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50 ; push_rax # allocate shadow stack space for UEFI function
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50 ; push_rax # allocate shadow stack space for UEFI function
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50 ; push_rax # allocate shadow stack space for UEFI function
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FF51 28 ; call_[rcx+BYTE] !40 # fout->write()
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4883C4 28 ; add_rsp, !40 # deallocate stack
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C3 ; ret # return
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:read_byte
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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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31F6 ; xor_esi,esi # zero rsi
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56 ; push_rsi # allocate stack
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4989E0 ; mov_r8,rsp # arg3 = &input
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50 ; push_rax # allocate shadow stack space for UEFI function
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50 ; push_rax # allocate shadow stack space for UEFI function
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50 ; push_rax # allocate shadow stack space for UEFI function
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FF51 20 ; call_[rcx+BYTE] !32 # fin->read()
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58 ; pop_rax # deallocate stack
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58 ; pop_rax # deallocate stack
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58 ; pop_rax # 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 !terminate ; je !terminate # then we are done
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C3 ; ret # return
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:terminate
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58 ; pop_rax # remove last return address from stack
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5E ; pop_rsi # restore rootdir
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415F ; pop_r15 # restore image_handle
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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 %SIMPLE_FS_PROTOCOL ; 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 %LOADED_IMAGE_PROTOCOL ; 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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4889EC ; mov_rsp,rbp # restore stack
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C3 ; ret # return to UEFI
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# Protocol GUIDs
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:LOADED_IMAGE_PROTOCOL
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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
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22 5B 4E 96 ; %0x0964e5b22
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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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:PE32_end
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