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< title > Mu - linux/104new-segment.subx< / title >
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< a href = 'https://github.com/akkartik/mu/blob/main/linux/104new-segment.subx' > https://github.com/akkartik/mu/blob/main/linux/104new-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 (pool of memory for allocating chunks from) in the form< / span >
< span id = "L2" class = "LineNr" > 2 < / span > < span class = "subxComment" > # of an *allocation descriptor* that can be passed to the memory allocator< / span >
< span id = "L3" class = "LineNr" > 3 < / span > < span class = "subxComment" > # (defined in a later layer).< / span >
< span id = "L4" class = "LineNr" > 4 < / span > < span class = "subxComment" > #< / span >
< span id = "L5" class = "LineNr" > 5 < / span > < span class = "subxComment" > # Currently an allocation descriptor consists of just the bounds of the pool of< / span >
< span id = "L6" class = "LineNr" > 6 < / span > < span class = "subxComment" > # available memory:< / span >
< span id = "L7" class = "LineNr" > 7 < / span > < span class = "subxComment" > #< / span >
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< span id = "L8" class = "LineNr" > 8 < / span > < span class = "subxComment" > # curr: address< / span >
< span id = "L9" class = "LineNr" > 9 < / span > < span class = "subxComment" > # end: address< / span >
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< span id = "L10" class = "LineNr" > 10 < / span > < span class = "subxComment" > #< / span >
< span id = "L11" class = "LineNr" > 11 < / span > < span class = "subxComment" > # This isn't enough information to reclaim individual allocations. We can't< / span >
< span id = "L12" class = "LineNr" > 12 < / span > < span class = "subxComment" > # support arbitrary reclamation yet.< / span >
< span id = "L13" class = "LineNr" > 13 < / span >
< span id = "L14" class = "LineNr" > 14 < / span > == code
< span id = "L15" class = "LineNr" > 15 < / span > < span class = "subxComment" > # instruction effective address register displacement immediate< / span >
< span id = "L16" class = "LineNr" > 16 < / span > < span class = "subxS1Comment" > # . op subop mod rm32 base index scale r32< / span >
< span id = "L17" class = "LineNr" > 17 < / 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 >
< span id = "L18" class = "LineNr" > 18 < / span >
< span id = "L19" class = "LineNr" > 19 < / span > < span class = "SpecialChar" > Entry< / span > : < span class = "subxComment" > # manual test< / span >
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< span id = "L20" class = "LineNr" > 20 < / span > < span class = "subxComment" > # var ad/ecx: allocation-descriptor< / span >
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< span id = "L21" class = "LineNr" > 21 < / span > 68/push 0/imm32/limit
< span id = "L22" class = "LineNr" > 22 < / span > 68/push 0/imm32/curr
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< span id = "L23" class = "LineNr" > 23 < / span > 89/copy 3/mod/direct 1/rm32/ecx < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 4/r32/esp < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "subxComment" > # copy esp to ecx< / span >
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< span id = "L24" class = "LineNr" > 24 < / span > < span class = "subxComment" > # new-segment(0x1000, ad)< / span >
< span id = "L25" class = "LineNr" > 25 < / span > < span class = "subxS2Comment" > # . . push args< / span >
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< span id = "L26" class = "LineNr" > 26 < / span > 51/push-ecx
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< span id = "L27" class = "LineNr" > 27 < / span > 68/push 0x1000/imm32
< span id = "L28" class = "LineNr" > 28 < / span > < span class = "subxS2Comment" > # . . call< / span >
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< span id = "L29" class = "LineNr" > 29 < / span > e8/call < a href = '104new-segment.subx.html#L40' > new-segment< / a > /disp32
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< span id = "L30" class = "LineNr" > 30 < / span > < span class = "subxS2Comment" > # . . discard args< / span >
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< span id = "L31" class = "LineNr" > 31 < / span > 81 0/subop/add 3/mod/direct 4/rm32/esp < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 8/imm32 < span class = "subxComment" > # add to esp< / span >
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< span id = "L32" class = "LineNr" > 32 < / span > < span class = "subxComment" > # var eax: (addr _) = ad-> curr< / span >
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< span id = "L33" class = "LineNr" > 33 < / span > 8b/copy 0/mod/indirect 1/rm32/ecx < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 0/r32/eax < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "subxComment" > # copy *ecx to eax< / span >
< span id = "L34" class = "LineNr" > 34 < / span > < span class = "subxComment" > # write to *eax to check that we have access to the newly-allocated segment< / span >
< span id = "L35" class = "LineNr" > 35 < / span > c7 0/subop/copy 0/mod/direct 0/rm32/eax < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 0x34/imm32 < span class = "subxComment" > # copy to *eax< / span >
< span id = "L36" class = "LineNr" > 36 < / span > < span class = "subxComment" > # syscall(exit, eax)< / span >
< span id = "L37" class = "LineNr" > 37 < / span > 89/copy 3/mod/direct 3/rm32/ebx < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 0/r32/eax < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "subxComment" > # copy eax to ebx< / span >
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< span id = "L38" class = "LineNr" > 38 < / span > e8/call < a href = '000init.subx.html#L18' > syscall_exit< / a > /disp32
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< span id = "L39" class = "LineNr" > 39 < / span >
< span id = "L40" class = "LineNr" > 40 < / span > < span class = "subxFunction" > new-segment< / span > : < span class = "subxComment" > # len: int, ad: (addr allocation-descriptor)< / span >
< span id = "L41" class = "LineNr" > 41 < / span > < span class = "subxS1Comment" > # . prologue< / span >
< span id = "L42" class = "LineNr" > 42 < / span > 55/push-ebp
< span id = "L43" class = "LineNr" > 43 < / span > 89/copy 3/mod/direct 5/rm32/ebp < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 4/r32/esp < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "subxComment" > # copy esp to ebp< / span >
< span id = "L44" class = "LineNr" > 44 < / span > < span class = "subxS1Comment" > # . save registers< / span >
< span id = "L45" class = "LineNr" > 45 < / span > 50/push-eax
< span id = "L46" class = "LineNr" > 46 < / span > 53/push-ebx
< span id = "L47" class = "LineNr" > 47 < / span > < span class = "subxComment" > # copy len to _mmap-new-segment-> len< / span >
< span id = "L48" class = "LineNr" > 48 < / span > 8b/copy 1/mod/*+disp8 5/rm32/ebp < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 0/r32/eax 8/disp8 < span class = "Normal" > . < / span > < span class = "subxComment" > # copy *(ebp+8) to eax< / span >
< span id = "L49" class = "LineNr" > 49 < / span > 89/copy 0/mod/indirect 5/rm32/.disp32 < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 0/r32/eax $_mmap-new-segment:len/disp32 < span class = "subxComment" > # copy eax to *$_mmap-new-segment:len< / span >
< span id = "L50" class = "LineNr" > 50 < / span > < span class = "subxComment" > # mmap(_mmap-new-segment)< / span >
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< span id = "L51" class = "LineNr" > 51 < / span > bb/copy-to-ebx < a href = '104new-segment.subx.html#L73' > _mmap-new-segment< / a > /imm32
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< span id = "L52" class = "LineNr" > 52 < / span > e8/call < a href = '000init.subx.html#L71' > syscall_mmap< / a > /disp32
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< span id = "L53" class = "LineNr" > 53 < / span > < span class = "subxComment" > # copy {eax, eax+len} to *ad< / span >
< span id = "L54" class = "LineNr" > 54 < / span > < span class = "subxS1Comment" > # . ebx = ad< / span >
< span id = "L55" class = "LineNr" > 55 < / span > 8b/copy 1/mod/*+disp8 5/rm32/ebp < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 3/r32/ebx 0xc/disp8 < span class = "Normal" > . < / span > < span class = "subxComment" > # copy *(ebp+12) to ebx< / span >
< span id = "L56" class = "LineNr" > 56 < / span > < span class = "subxS1Comment" > # . ad-> curr = eax< / span >
< span id = "L57" class = "LineNr" > 57 < / span > 89/copy 0/mod/indirect 3/rm32/ebx < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 0/r32/eax < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "subxComment" > # copy eax to *ebx< / span >
< span id = "L58" class = "LineNr" > 58 < / span > < span class = "subxS1Comment" > # . ad-> end = eax+len< / span >
< span id = "L59" class = "LineNr" > 59 < / span > 03/add 1/mod/*+disp8 5/rm32/ebp < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 0/r32/eax 8/disp8 < span class = "Normal" > . < / span > < span class = "subxComment" > # add *(ebp+8) to eax< / span >
< span id = "L60" class = "LineNr" > 60 < / span > 89/copy 1/mod/*+disp8 3/rm32/ebx < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 0/r32/eax 4/disp8 < span class = "Normal" > . < / span > < span class = "subxComment" > # copy eax to *(ebx+4)< / span >
< span id = "L61" class = "LineNr" > 61 < / span > < span class = "Constant" > $new-segment:end< / span > :
< span id = "L62" class = "LineNr" > 62 < / span > < span class = "subxS1Comment" > # . restore registers< / span >
< span id = "L63" class = "LineNr" > 63 < / span > 5b/pop-to-ebx
< span id = "L64" class = "LineNr" > 64 < / span > 58/pop-to-eax
< span id = "L65" class = "LineNr" > 65 < / span > < span class = "subxS1Comment" > # . epilogue< / span >
< span id = "L66" class = "LineNr" > 66 < / span > 89/copy 3/mod/direct 4/rm32/esp < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > 5/r32/ebp < span class = "Normal" > . < / span > < span class = "Normal" > . < / span > < span class = "subxComment" > # copy ebp to esp< / span >
< span id = "L67" class = "LineNr" > 67 < / span > 5d/pop-to-ebp
< span id = "L68" class = "LineNr" > 68 < / span > c3/return
< span id = "L69" class = "LineNr" > 69 < / span >
< span id = "L70" class = "LineNr" > 70 < / span > == data
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< span id = "L71" class = "LineNr" > 71 < / span >
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< span id = "L72" class = "LineNr" > 72 < / span > < span class = "subxComment" > # various constants used here were found in the Linux sources (search for file mman-common.h)< / span >
< span id = "L73" class = "LineNr" > 73 < / span > < span class = "subxMinorFunction" > _mmap-new-segment< / span > : < span class = "subxComment" > # mmap_arg_struct< / span >
< span id = "L74" class = "LineNr" > 74 < / span > < span class = "subxComment" > # addr< / span >
< span id = "L75" class = "LineNr" > 75 < / span > 0/imm32
< span id = "L76" class = "LineNr" > 76 < / span > < span class = "Constant" > $_mmap-new-segment:len< / span > :
< span id = "L77" class = "LineNr" > 77 < / span > < span class = "subxComment" > # len< / span >
< span id = "L78" class = "LineNr" > 78 < / span > 0/imm32
< span id = "L79" class = "LineNr" > 79 < / span > < span class = "subxComment" > # protection flags< / span >
< span id = "L80" class = "LineNr" > 80 < / span > 3/imm32 < span class = "subxComment" > # PROT_READ | PROT_WRITE< / span >
< span id = "L81" class = "LineNr" > 81 < / span > < span class = "subxComment" > # sharing flags< / span >
< span id = "L82" class = "LineNr" > 82 < / span > 0x22/imm32 < span class = "subxComment" > # MAP_PRIVATE | MAP_ANONYMOUS< / span >
< span id = "L83" class = "LineNr" > 83 < / span > < span class = "subxComment" > # fd< / span >
< span id = "L84" class = "LineNr" > 84 < / span > -1/imm32 < span class = "subxComment" > # since MAP_ANONYMOUS is specified< / span >
< span id = "L85" class = "LineNr" > 85 < / span > < span class = "subxComment" > # offset< / span >
< span id = "L86" class = "LineNr" > 86 < / span > 0/imm32 < span class = "subxComment" > # since MAP_ANONYMOUS is specified< / span >
< span id = "L87" class = "LineNr" > 87 < / span >
< span id = "L88" class = "LineNr" > 88 < / span > < span class = "subxS2Comment" > # . . vim: nowrap:textwidth=0< / span >
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