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< a href = 'https://github.com/akkartik/mu/blob/master/subx/053new_segment.subx' > https://github.com/akkartik/mu/blob/master/subx/053new_segment.subx< / a >
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< pre id = 'vimCodeElement' >
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< span id = "L1" class = "LineNr" > 1 < / span > < span class = "subxComment" > # Create a new segment (for data) using mmap().< / span >
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< span id = "L2" class = "LineNr" > 2 < / span >
< span id = "L3" class = "LineNr" > 3 < / span > == code
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< span id = "L4" class = "LineNr" > 4 < / span > < span class = "subxComment" > # instruction effective address register displacement immediate< / span >
< span id = "L5" class = "LineNr" > 5 < / span > < span class = "subxS1Comment" > # . op subop mod rm32 base index scale r32< / span >
< span id = "L6" class = "LineNr" > 6 < / span > < span class = "subxS1Comment" > # . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes< / span >
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< span id = "L7" class = "LineNr" > 7 < / span >
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< span id = "L8" class = "LineNr" > 8 < / span > < span class = "subxComment" > # main: (manual test if this is the last file loaded)< / span >
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< span id = "L9" class = "LineNr" > 9 < / span > < span class = "subxComment" > # EAX = new-segment(0x1000)< / span >
< span id = "L10" class = "LineNr" > 10 < / span > < span class = "subxS2Comment" > # . . push args< / span >
< span id = "L11" class = "LineNr" > 11 < / span > 68/push 0x1000/imm32
< span id = "L12" class = "LineNr" > 12 < / span > < span class = "subxS2Comment" > # . . call< / span >
< span id = "L13" class = "LineNr" > 13 < / span > e8/call new-segment/disp32
< span id = "L14" class = "LineNr" > 14 < / span > < span class = "subxS2Comment" > # . . discard args< / span >
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< span id = "L15" class = "LineNr" > 15 < / span > 81 0/subop/add 3/mod/direct 4/rm32/ESP < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > 4/imm32 < span class = "subxComment" > # add to ESP< / span >
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< span id = "L16" class = "LineNr" > 16 < / span >
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< span id = "L17" class = "LineNr" > 17 < / span > < span class = "subxComment" > # write to *EAX to check that we have access to the newly-allocated segment< / span >
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< span id = "L18" class = "LineNr" > 18 < / span > c7/copy 0/mod/direct 0/rm32/EAX < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > 0x34/imm32 < span class = "subxComment" > # copy to *EAX< / span >
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< span id = "L19" class = "LineNr" > 19 < / span >
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< span id = "L20" class = "LineNr" > 20 < / span > < span class = "subxComment" > # syscall(exit, EAX)< / span >
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< span id = "L21" class = "LineNr" > 21 < / span > 89/copy 3/mod/direct 3/rm32/EBX < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > 0/r32/EAX < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "subxComment" > # copy EAX to EBX< / span >
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< span id = "L22" class = "LineNr" > 22 < / span > b8/copy-to-EAX 1/imm32/exit
< span id = "L23" class = "LineNr" > 23 < / span > cd/syscall 0x80/imm8
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< span id = "L24" class = "LineNr" > 24 < / span >
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< span id = "L25" class = "LineNr" > 25 < / span > < span class = "subxFunction" > new-segment< / span > : < span class = "subxComment" > # len : int -> address< / span >
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< span id = "L26" class = "LineNr" > 26 < / span > < span class = "subxS1Comment" > # . prolog< / span >
< span id = "L27" class = "LineNr" > 27 < / span > 55/push-EBP
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< span id = "L28" class = "LineNr" > 28 < / span > 89/copy 3/mod/direct 5/rm32/EBP < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > 4/r32/ESP < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "subxComment" > # copy ESP to EBP< / span >
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< span id = "L29" class = "LineNr" > 29 < / span > 53/push-EBX
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< span id = "L30" class = "LineNr" > 30 < / span > < span class = "subxComment" > # copy len to _mmap-new-segment-> len< / span >
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< span id = "L31" class = "LineNr" > 31 < / span > < span class = "subxComment" > # TODO: compute _mmap-new-segment+4 before runtime< / span >
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< span id = "L32" class = "LineNr" > 32 < / span > 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none < span class = "CommentedCode" > . < / span > 0/r32/EAX 8/disp8 < span class = "CommentedCode" > . < / span > < span class = "subxComment" > # copy *(EBP+8) to EAX< / span >
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< span id = "L33" class = "LineNr" > 33 < / span > bb/copy-to-EBX _mmap-new-segment/imm32
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< span id = "L34" class = "LineNr" > 34 < / span > 89/copy 1/mod/*+disp8 3/rm32/EBX < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > 0/r32/EAX 4/disp8 < span class = "CommentedCode" > . < / span > < span class = "subxComment" > # copy EAX to *(EBX+4)< / span >
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< span id = "L35" class = "LineNr" > 35 < / span > < span class = "subxComment" > # mmap(_mmap-new-segment)< / span >
< span id = "L36" class = "LineNr" > 36 < / span > bb/copy-to-EBX _mmap-new-segment/imm32
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< span id = "L37" class = "LineNr" > 37 < / span > b8/copy-to-EAX 0x5a/imm32/mmap
< span id = "L38" class = "LineNr" > 38 < / span > cd/syscall 0x80/imm8
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< span id = "L39" class = "LineNr" > 39 < / span > < span class = "Constant" > $new-segment:end< / span > :
< span id = "L40" class = "LineNr" > 40 < / span > < span class = "subxS1Comment" > # . epilog< / span >
< span id = "L41" class = "LineNr" > 41 < / span > 5b/pop-to-EBX
< span id = "L42" class = "LineNr" > 42 < / span > 89/copy 3/mod/direct 4/rm32/ESP < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > 5/r32/EBP < span class = "CommentedCode" > . < / span > < span class = "CommentedCode" > . < / span > < span class = "subxComment" > # copy EBP to ESP< / span >
< span id = "L43" class = "LineNr" > 43 < / span > 5d/pop-to-EBP
< span id = "L44" class = "LineNr" > 44 < / span > c3/return
< span id = "L45" class = "LineNr" > 45 < / span >
< span id = "L46" class = "LineNr" > 46 < / span > == data
< span id = "L47" class = "LineNr" > 47 < / span >
< span id = "L48" class = "LineNr" > 48 < / span > < span class = "subxComment" > # various constants used here were found in the Linux sources (search for file mman-common.h)< / span >
< span id = "L49" class = "LineNr" > 49 < / span > < span class = "subxMinorFunction" > _mmap-new-segment< / span > : < span class = "subxComment" > # type mmap_arg_struct< / span >
< span id = "L50" class = "LineNr" > 50 < / span > < span class = "subxComment" > # addr< / span >
< span id = "L51" class = "LineNr" > 51 < / span > 00 00 00 00 < span class = "subxComment" > # null< / span >
< span id = "L52" class = "LineNr" > 52 < / span > < span class = "subxComment" > # len< / span >
< span id = "L53" class = "LineNr" > 53 < / span > 00 00 00 00 < span class = "subxComment" > # 0x1000< / span >
< span id = "L54" class = "LineNr" > 54 < / span > < span class = "subxComment" > # protection flags< / span >
< span id = "L55" class = "LineNr" > 55 < / span > 03 00 00 00 < span class = "subxComment" > # PROT_READ | PROT_WRITE< / span >
< span id = "L56" class = "LineNr" > 56 < / span > < span class = "subxComment" > # sharing flags< / span >
< span id = "L57" class = "LineNr" > 57 < / span > 22 00 00 00 < span class = "subxComment" > # MAP_PRIVATE | MAP_ANONYMOUS< / span >
< span id = "L58" class = "LineNr" > 58 < / span > < span class = "subxComment" > # fd< / span >
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< span id = "L59" class = "LineNr" > 59 < / span > ff ff ff ff < span class = "subxComment" > # -1 since MAP_ANONYMOUS is specified< / span >
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< span id = "L60" class = "LineNr" > 60 < / span > < span class = "subxComment" > # offset< / span >
< span id = "L61" class = "LineNr" > 61 < / span > 00 00 00 00 < span class = "subxComment" > # 0 since MAP_ANONYMOUS is specified< / span >
< span id = "L62" class = "LineNr" > 62 < / span >
< span id = "L63" class = "LineNr" > 63 < / span > < span class = "subxS2Comment" > # . . vim: nowrap:textwidth=0< / span >
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