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authorKartik Agaram <vc@akkartik.com>2019-01-03 17:02:17 -0800
committerKartik Agaram <vc@akkartik.com>2019-01-03 17:02:17 -0800
commit634b162a980f72ae1d822e593f7975fa8e1ad3e8 (patch)
tree9f3cd2b8c3a6445c36268392fc8ef2bf820401d6 /html/subx/053new-segment.subx.html
parent1ffb27a045c63217336e2c926058360e9521afc9 (diff)
downloadmu-634b162a980f72ae1d822e593f7975fa8e1ad3e8.tar.gz
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+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
+<html>
+<head>
+<meta http-equiv="content-type" content="text/html; charset=UTF-8">
+<title>Mu - subx/053new_segment.subx</title>
+<meta name="Generator" content="Vim/8.0">
+<meta name="plugin-version" content="vim7.4_v2">
+<meta name="syntax" content="none">
+<meta name="settings" content="number_lines,use_css,no_foldcolumn,expand_tabs,line_ids,prevent_copy=">
+<meta name="colorscheme" content="minimal-light">
+<style type="text/css">
+<!--
+pre { font-family: monospace; color: #000000; background-color: #c6c6c6; }
+body { font-size:12pt; font-family: monospace; color: #000000; background-color: #c6c6c6; }
+a { color:inherit; }
+* { font-size:12pt; font-size: 1em; }
+.subxComment { color: #005faf; }
+.subxS2Comment { color: #8a8a8a; }
+.subxMinorFunction { color: #875f5f; }
+.LineNr { }
+.subxS1Comment { color: #0000af; }
+.subxFunction { color: #af5f00; text-decoration: underline; }
+.Constant { color: #008787; }
+.Normal { color: #000000; background-color: #c6c6c6; padding-bottom: 1px; }
+-->
+</style>
+
+<script type='text/javascript'>
+<!--
+
+/* function to open any folds containing a jumped-to line before jumping to it */
+function JumpToLine()
+{
+  var lineNum;
+  lineNum = window.location.hash;
+  lineNum = lineNum.substr(1); /* strip off '#' */
+
+  if (lineNum.indexOf('L') == -1) {
+    lineNum = 'L'+lineNum;
+  }
+  lineElem = document.getElementById(lineNum);
+  /* Always jump to new location even if the line was hidden inside a fold, or
+   * we corrected the raw number to a line ID.
+   */
+  if (lineElem) {
+    lineElem.scrollIntoView(true);
+  }
+  return true;
+}
+if ('onhashchange' in window) {
+  window.onhashchange = JumpToLine;
+}
+
+-->
+</script>
+</head>
+<body onload='JumpToLine();'>
+<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>
+<pre id='vimCodeElement'>
+<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># Create a new segment (for data) using mmap().</span>
+<span id="L2" class="LineNr"> 2 </span>
+<span id="L3" class="LineNr"> 3 </span>== code
+<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>
+<span id="L7" class="LineNr"> 7 </span>
+<span id="L8" class="LineNr"> 8 </span><span class="subxComment"># main:  (manual test if this is the last file loaded)</span>
+<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  <a href='053new_segment.subx.html#L25'>new-segment</a>/disp32
+<span id="L14" class="LineNr">14 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L15" class="LineNr">15 </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>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L16" class="LineNr">16 </span>
+<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>
+<span id="L18" class="LineNr">18 </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="L19" class="LineNr">19 </span>
+<span id="L20" class="LineNr">20 </span>    <span class="subxComment"># syscall(exit, EAX)</span>
+<span id="L21" class="LineNr">21 </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>
+<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
+<span id="L24" class="LineNr">24 </span>
+<span id="L25" class="LineNr">25 </span><span class="subxFunction">new-segment</span>:  <span class="subxComment"># len : int -&gt; address</span>
+<span id="L26" class="LineNr">26 </span>    <span class="subxS1Comment"># . prolog</span>
+<span id="L27" class="LineNr">27 </span>    55/push-EBP
+<span id="L28" class="LineNr">28 </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="L29" class="LineNr">29 </span>    53/push-EBX
+<span id="L30" class="LineNr">30 </span>    <span class="subxComment"># copy len to _mmap-new-segment-&gt;len</span>
+<span id="L31" class="LineNr">31 </span>    <span class="subxComment"># TODO: compute _mmap-new-segment+4 before runtime</span>
+<span id="L32" class="LineNr">32 </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="L33" class="LineNr">33 </span>    bb/copy-to-EBX  <a href='053new_segment.subx.html#L49'>_mmap-new-segment</a>/imm32
+<span id="L34" class="LineNr">34 </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="L35" class="LineNr">35 </span>    <span class="subxComment"># mmap(_mmap-new-segment)</span>
+<span id="L36" class="LineNr">36 </span>    bb/copy-to-EBX  <a href='053new_segment.subx.html#L49'>_mmap-new-segment</a>/imm32
+<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
+<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="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="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>
+<span id="L59" class="LineNr">59 </span>    ff ff ff ff  <span class="subxComment"># -1 since MAP_ANONYMOUS is specified</span>
+<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&#0058;nowrap:textwidth=0</span>
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->

 

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