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| author | Kartik Agaram <vc@akkartik.com> | 2018-08-13 21:25:22 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2018-08-13 21:25:22 -0700 |
| commit | 7328af20a1921d9258a60803ee5367da97a6082e (patch) | |
| tree | e809d6cff85f290073a71982a5d24255848678ac /html/subx/029translate.cc.html | |
| parent | 5cec03b41425940ff5fa73c10ea8fb402a3b5ffa (diff) | |
| download | mu-7328af20a1921d9258a60803ee5367da97a6082e.tar.gz | |
4521
Diffstat (limited to 'html/subx/029translate.cc.html')
| -rw-r--r-- | html/subx/029translate.cc.html | 288 |
1 files changed, 0 insertions, 288 deletions
diff --git a/html/subx/029translate.cc.html b/html/subx/029translate.cc.html deleted file mode 100644 index 53e77fa0..00000000 --- a/html/subx/029translate.cc.html +++ /dev/null @@ -1,288 +0,0 @@ -<!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/029translate.cc</title> -<meta name="Generator" content="Vim/7.4"> -<meta name="plugin-version" content="vim7.4_v2"> -<meta name="syntax" content="cpp"> -<meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy="> -<meta name="colorscheme" content="minimal"> -<style type="text/css"> -<!-- -pre { white-space: pre-wrap; font-family: monospace; color: #aaaaaa; background-color: #080808; } -body { font-size: 12pt; font-family: monospace; color: #aaaaaa; background-color: #080808; } -a { color:#eeeeee; text-decoration: none; } -a:hover { text-decoration: underline; } -* { font-size: 12pt; font-size: 1em; } -.Constant { color: #00a0a0; } -.SalientComment { color: #00ffff; } -.Comment { color: #9090ff; } -.Comment a { color:#0000ee; text-decoration:underline; } -.Delimiter { color: #800080; } -.LineNr { color: #444444; } -.Identifier { color: #c0a020; } -.Normal { color: #aaaaaa; background-color: #080808; padding-bottom: 1px; } -.cSpecial { color: #008000; } ---> -</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();'> -<pre id='vimCodeElement'> -<span id="L1" class="LineNr"> 1 </span><span class="Comment">//: The bedrock level 1 of abstraction is now done, and we're going to start</span> -<span id="L2" class="LineNr"> 2 </span><span class="Comment">//: building levels above it that make programming in x86 machine code a</span> -<span id="L3" class="LineNr"> 3 </span><span class="Comment">//: little more ergonomic.</span> -<span id="L4" class="LineNr"> 4 </span><span class="Comment">//:</span> -<span id="L5" class="LineNr"> 5 </span><span class="Comment">//: All levels will be "pass through by default". Whatever they don't</span> -<span id="L6" class="LineNr"> 6 </span><span class="Comment">//: understand they will silently pass through to lower levels.</span> -<span id="L7" class="LineNr"> 7 </span><span class="Comment">//:</span> -<span id="L8" class="LineNr"> 8 </span><span class="Comment">//: Since raw hex bytes of machine code are always possible to inject, SubX is</span> -<span id="L9" class="LineNr"> 9 </span><span class="Comment">//: not a language, and we aren't building a compiler. This is something</span> -<span id="L10" class="LineNr"> 10 </span><span class="Comment">//: deliberately leakier. Levels are more for improving auditing, checks and</span> -<span id="L11" class="LineNr"> 11 </span><span class="Comment">//: error messages rather than for hiding low-level details.</span> -<span id="L12" class="LineNr"> 12 </span> -<span id="L13" class="LineNr"> 13 </span><span class="Comment">//: Translator workflow: read 'source' file. Run a series of transforms on it,</span> -<span id="L14" class="LineNr"> 14 </span><span class="Comment">//: each passing through what it doesn't understand. The final program should</span> -<span id="L15" class="LineNr"> 15 </span><span class="Comment">//: be just machine code, suitable to write to an ELF binary.</span> -<span id="L16" class="LineNr"> 16 </span><span class="Comment">//:</span> -<span id="L17" class="LineNr"> 17 </span><span class="Comment">//: Higher levels usually transform code on the basis of metadata.</span> -<span id="L18" class="LineNr"> 18 </span> -<span id="L19" class="LineNr"> 19 </span><span class="Delimiter">:(before "End Main")</span> -<span id="L20" class="LineNr"> 20 </span><span class="Normal">if</span> <span class="Delimiter">(</span><a href='001help.cc.html#L89'>is_equal</a><span class="Delimiter">(</span>argv[<span class="Constant">1</span>]<span class="Delimiter">,</span> <span class="Constant">"translate"</span><span class="Delimiter">))</span> <span class="Delimiter">{</span> -<span id="L21" class="LineNr"> 21 </span> <a href='003trace.cc.html#L238'>START_TRACING_UNTIL_END_OF_SCOPE</a><span class="Delimiter">;</span> -<span id="L22" class="LineNr"> 22 </span> assert<span class="Delimiter">(</span>argc > <span class="Constant">3</span><span class="Delimiter">);</span> -<span id="L23" class="LineNr"> 23 </span> <a href='011run.cc.html#L96'>program</a> p<span class="Delimiter">;</span> -<span id="L24" class="LineNr"> 24 </span> ifstream fin<span class="Delimiter">(</span>argv[<span class="Constant">2</span>]<span class="Delimiter">);</span> -<span id="L25" class="LineNr"> 25 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>!fin<span class="Delimiter">)</span> <span class="Delimiter">{</span> -<span id="L26" class="LineNr"> 26 </span> cerr << <span class="Constant">"could not open "</span> << argv[<span class="Constant">2</span>] << <span class="cSpecial">'\n'</span><span class="Delimiter">;</span> -<span id="L27" class="LineNr"> 27 </span> <span class="Identifier">return</span> <span class="Constant">1</span><span class="Delimiter">;</span> -<span id="L28" class="LineNr"> 28 </span> <span class="Delimiter">}</span> -<span id="L29" class="LineNr"> 29 </span> <a href='011run.cc.html#L124'>parse</a><span class="Delimiter">(</span>fin<span class="Delimiter">,</span> p<span class="Delimiter">);</span> -<span id="L30" class="LineNr"> 30 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><a href='003trace.cc.html#L210'>trace_contains_errors</a><span class="Delimiter">())</span> <span class="Identifier">return</span> <span class="Constant">1</span><span class="Delimiter">;</span> -<span id="L31" class="LineNr"> 31 </span> transform<span class="Delimiter">(</span>p<span class="Delimiter">);</span> -<span id="L32" class="LineNr"> 32 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><a href='003trace.cc.html#L210'>trace_contains_errors</a><span class="Delimiter">())</span> <span class="Identifier">return</span> <span class="Constant">1</span><span class="Delimiter">;</span> -<span id="L33" class="LineNr"> 33 </span> <a href='029translate.cc.html#L105'>save_elf</a><span class="Delimiter">(</span>p<span class="Delimiter">,</span> argv[<span class="Constant">3</span>]<span class="Delimiter">);</span> -<span id="L34" class="LineNr"> 34 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><a href='003trace.cc.html#L210'>trace_contains_errors</a><span class="Delimiter">())</span> unlink<span class="Delimiter">(</span>argv[<span class="Constant">3</span>]<span class="Delimiter">);</span> -<span id="L35" class="LineNr"> 35 </span> <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span> -<span id="L36" class="LineNr"> 36 </span><span class="Delimiter">}</span> -<span id="L37" class="LineNr"> 37 </span> -<span id="L38" class="LineNr"> 38 </span><span class="Comment">//: Ordering transforms is a well-known hard problem when building compilers.</span> -<span id="L39" class="LineNr"> 39 </span><span class="Comment">//: In our case we also have the additional notion of layers. The ordering of</span> -<span id="L40" class="LineNr"> 40 </span><span class="Comment">//: layers can have nothing in common with the ordering of transforms when</span> -<span id="L41" class="LineNr"> 41 </span><span class="Comment">//: SubX is tangled and run. This can be confusing for readers, particularly</span> -<span id="L42" class="LineNr"> 42 </span><span class="Comment">//: if later layers start inserting transforms at arbitrary points between</span> -<span id="L43" class="LineNr"> 43 </span><span class="Comment">//: transforms introduced earlier. Over time adding transforms can get harder</span> -<span id="L44" class="LineNr"> 44 </span><span class="Comment">//: and harder, having to meet the constraints of everything that's come</span> -<span id="L45" class="LineNr"> 45 </span><span class="Comment">//: before. It's worth thinking about organization up-front so the ordering is</span> -<span id="L46" class="LineNr"> 46 </span><span class="Comment">//: easy to hold in our heads, and it's obvious where to add a new transform.</span> -<span id="L47" class="LineNr"> 47 </span><span class="Comment">//: Some constraints:</span> -<span id="L48" class="LineNr"> 48 </span><span class="Comment">//:</span> -<span id="L49" class="LineNr"> 49 </span><span class="Comment">//: 1. Layers force us to build SubX bottom-up; since we want to be able to</span> -<span id="L50" class="LineNr"> 50 </span><span class="Comment">//: build and run SubX after stopping loading at any layer, the overall</span> -<span id="L51" class="LineNr"> 51 </span><span class="Comment">//: organization has to be to introduce primitives before we start using</span> -<span id="L52" class="LineNr"> 52 </span><span class="Comment">//: them.</span> -<span id="L53" class="LineNr"> 53 </span><span class="Comment">//:</span> -<span id="L54" class="LineNr"> 54 </span><span class="Comment">//: 2. Transforms usually need to be run top-down, converting high-level</span> -<span id="L55" class="LineNr"> 55 </span><span class="Comment">//: representations to low-level ones so that low-level layers can be</span> -<span id="L56" class="LineNr"> 56 </span><span class="Comment">//: oblivious to them.</span> -<span id="L57" class="LineNr"> 57 </span><span class="Comment">//:</span> -<span id="L58" class="LineNr"> 58 </span><span class="Comment">//: 3. When running we'd often like new representations to be checked before</span> -<span id="L59" class="LineNr"> 59 </span><span class="Comment">//: they are transformed away. The whole reason for new representations is</span> -<span id="L60" class="LineNr"> 60 </span><span class="Comment">//: often to add new kinds of automatic checking for our machine code</span> -<span id="L61" class="LineNr"> 61 </span><span class="Comment">//: programs.</span> -<span id="L62" class="LineNr"> 62 </span><span class="Comment">//:</span> -<span id="L63" class="LineNr"> 63 </span><span class="Comment">//: Putting these constraints together, we'll use the following broad</span> -<span id="L64" class="LineNr"> 64 </span><span class="Comment">//: organization:</span> -<span id="L65" class="LineNr"> 65 </span><span class="Comment">//:</span> -<span id="L66" class="LineNr"> 66 </span><span class="Comment">//: a) We'll divide up our transforms into "levels", each level consisting</span> -<span id="L67" class="LineNr"> 67 </span><span class="Comment">//: of multiple transforms, and dealing in some new set of representational</span> -<span id="L68" class="LineNr"> 68 </span><span class="Comment">//: ideas. Levels will be added in reverse order to the one their transforms</span> -<span id="L69" class="LineNr"> 69 </span><span class="Comment">//: will be run in.</span> -<span id="L70" class="LineNr"> 70 </span><span class="Comment">//:</span> -<span id="L71" class="LineNr"> 71 </span><span class="Comment">//: To run all transforms:</span> -<span id="L72" class="LineNr"> 72 </span><span class="Comment">//: Load transforms for level n</span> -<span id="L73" class="LineNr"> 73 </span><span class="Comment">//: Load transforms for level n-1</span> -<span id="L74" class="LineNr"> 74 </span><span class="Comment">//: ...</span> -<span id="L75" class="LineNr"> 75 </span><span class="Comment">//: Load transforms for level 2</span> -<span id="L76" class="LineNr"> 76 </span><span class="Comment">//: Run code at level 1</span> -<span id="L77" class="LineNr"> 77 </span><span class="Comment">//:</span> -<span id="L78" class="LineNr"> 78 </span><span class="Comment">//: b) *Within* a level we'll usually introduce transforms in the order</span> -<span id="L79" class="LineNr"> 79 </span><span class="Comment">//: they're run in.</span> -<span id="L80" class="LineNr"> 80 </span><span class="Comment">//:</span> -<span id="L81" class="LineNr"> 81 </span><span class="Comment">//: To run transforms for level n:</span> -<span id="L82" class="LineNr"> 82 </span><span class="Comment">//: Perform transform of layer l</span> -<span id="L83" class="LineNr"> 83 </span><span class="Comment">//: Perform transform of layer l+1</span> -<span id="L84" class="LineNr"> 84 </span><span class="Comment">//: ...</span> -<span id="L85" class="LineNr"> 85 </span><span class="Comment">//:</span> -<span id="L86" class="LineNr"> 86 </span><span class="Comment">//: c) Within a level it's often most natural to introduce a new</span> -<span id="L87" class="LineNr"> 87 </span><span class="Comment">//: representation by showing how it's transformed to the level below. To</span> -<span id="L88" class="LineNr"> 88 </span><span class="Comment">//: make such exceptions more obvious checks usually won't be first-class</span> -<span id="L89" class="LineNr"> 89 </span><span class="Comment">//: transforms; instead code that keeps the program unmodified will run</span> -<span id="L90" class="LineNr"> 90 </span><span class="Comment">//: within transforms before they mutate the program.</span> -<span id="L91" class="LineNr"> 91 </span><span class="Comment">//:</span> -<span id="L92" class="LineNr"> 92 </span><span class="Comment">//: Level l transforms programs</span> -<span id="L93" class="LineNr"> 93 </span><span class="Comment">//: Level l+1 inserts checks to run *before* the transform of level l runs</span> -<span id="L94" class="LineNr"> 94 </span><span class="Comment">//:</span> -<span id="L95" class="LineNr"> 95 </span><span class="Comment">//: This may all seem abstract, but will hopefully make sense over time. The</span> -<span id="L96" class="LineNr"> 96 </span><span class="Comment">//: goals are basically to always have a working program after any layer, to</span> -<span id="L97" class="LineNr"> 97 </span><span class="Comment">//: have the order of layers make narrative sense, and to order transforms</span> -<span id="L98" class="LineNr"> 98 </span><span class="Comment">//: correctly at runtime.</span> -<span id="L99" class="LineNr"> 99 </span><span class="Delimiter">:(before "End One-time Setup")</span> -<span id="L100" class="LineNr">100 </span><span class="Comment">// Begin Transforms</span> -<span id="L101" class="LineNr">101 </span><span class="Comment">// End Transforms</span> -<span id="L102" class="LineNr">102 </span> -<span id="L103" class="LineNr">103 </span><span class="Delimiter">:(code)</span> -<span id="L104" class="LineNr">104 </span><span class="Comment">// write out a program to a bare-bones ELF file</span> -<span id="L105" class="LineNr">105 </span><span class="Normal">void</span> <a href='029translate.cc.html#L105'>save_elf</a><span class="Delimiter">(</span><span class="Normal">const</span> program& p<span class="Delimiter">,</span> <span class="Normal">const</span> <span class="Normal">char</span>* filename<span class="Delimiter">)</span> <span class="Delimiter">{</span> -<span id="L106" class="LineNr">106 </span> ofstream out<span class="Delimiter">(</span>filename<span class="Delimiter">,</span> ios::binary<span class="Delimiter">);</span> -<span id="L107" class="LineNr">107 </span> <a href='029translate.cc.html#L113'>write_elf_header</a><span class="Delimiter">(</span>out<span class="Delimiter">,</span> p<span class="Delimiter">);</span> -<span id="L108" class="LineNr">108 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">size_t</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">.</span>size<span class="Delimiter">();</span> ++i<span class="Delimiter">)</span> -<span id="L109" class="LineNr">109 </span> <a href='029translate.cc.html#L206'>write_segment</a><span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">),</span> out<span class="Delimiter">);</span> -<span id="L110" class="LineNr">110 </span> out<span class="Delimiter">.</span>close<span class="Delimiter">();</span> -<span id="L111" class="LineNr">111 </span><span class="Delimiter">}</span> -<span id="L112" class="LineNr">112 </span> -<span id="L113" class="LineNr">113 </span><span class="Normal">void</span> <a href='029translate.cc.html#L113'>write_elf_header</a><span class="Delimiter">(</span>ostream& out<span class="Delimiter">,</span> <span class="Normal">const</span> program& p<span class="Delimiter">)</span> <span class="Delimiter">{</span> -<span id="L114" class="LineNr">114 </span> <span class="Normal">char</span> c = <span class="cSpecial">'\0'</span><span class="Delimiter">;</span> -<span id="L115" class="LineNr">115 </span><span class="Comment">#define O(X) c = (X); out.write(&c, sizeof(c))</span> -<span id="L116" class="LineNr">116 </span><span class="Comment">// host is required to be little-endian</span> -<span id="L117" class="LineNr">117 </span><span class="Comment">#define emit(X) out.write(reinterpret_cast<const char*>(&X), sizeof(X))</span> -<span id="L118" class="LineNr">118 </span> <span class="SalientComment">//// ehdr</span> -<span id="L119" class="LineNr">119 </span> <span class="Comment">// e_ident</span> -<span id="L120" class="LineNr">120 </span> O<span class="Delimiter">(</span><span class="Constant">0x7f</span><span class="Delimiter">);</span> O<span class="Delimiter">(</span><span class="Comment">/*</span><span class="Comment">E</span><span class="Comment">*/</span><span class="Constant">0x45</span><span class="Delimiter">);</span> O<span class="Delimiter">(</span><span class="Comment">/*</span><span class="Comment">L</span><span class="Comment">*/</span><span class="Constant">0x4c</span><span class="Delimiter">);</span> O<span class="Delimiter">(</span><span class="Comment">/*</span><span class="Comment">F</span><span class="Comment">*/</span><span class="Constant">0x46</span><span class="Delimiter">);</span> -<span id="L121" class="LineNr">121 </span> O<span class="Delimiter">(</span><span class="Constant">0x1</span><span class="Delimiter">);</span> <span class="Comment">// 32-bit format</span> -<span id="L122" class="LineNr">122 </span> O<span class="Delimiter">(</span><span class="Constant">0x1</span><span class="Delimiter">);</span> <span class="Comment">// little-endian</span> -<span id="L123" class="LineNr">123 </span> O<span class="Delimiter">(</span><span class="Constant">0x1</span><span class="Delimiter">);</span> O<span class="Delimiter">(</span><span class="Constant">0x0</span><span class="Delimiter">);</span> -<span id="L124" class="LineNr">124 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">size_t</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < <span class="Constant">8</span><span class="Delimiter">;</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span> O<span class="Delimiter">(</span><span class="Constant">0x0</span><span class="Delimiter">);</span> <span class="Delimiter">}</span> -<span id="L125" class="LineNr">125 </span> <span class="Comment">// e_type</span> -<span id="L126" class="LineNr">126 </span> O<span class="Delimiter">(</span><span class="Constant">0x02</span><span class="Delimiter">);</span> O<span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span> -<span id="L127" class="LineNr">127 </span> <span class="Comment">// e_machine</span> -<span id="L128" class="LineNr">128 </span> O<span class="Delimiter">(</span><span class="Constant">0x03</span><span class="Delimiter">);</span> O<span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span> -<span id="L129" class="LineNr">129 </span> <span class="Comment">// e_version</span> -<span id="L130" class="LineNr">130 </span> O<span class="Delimiter">(</span><span class="Constant">0x01</span><span class="Delimiter">);</span> O<span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span> O<span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span> O<span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span> -<span id="L131" class="LineNr">131 </span> <span class="Comment">// e_entry</span> -<span id="L132" class="LineNr">132 </span> <span class="Normal">int</span> e_entry = p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span><a href='011run.cc.html#L105'>start</a><span class="Delimiter">;</span> <span class="Comment">// convention</span> -<span id="L133" class="LineNr">133 </span> emit<span class="Delimiter">(</span>e_entry<span class="Delimiter">);</span> -<span id="L134" class="LineNr">134 </span> <span class="Comment">// e_phoff -- immediately after ELF header</span> -<span id="L135" class="LineNr">135 </span> <span class="Normal">int</span> e_phoff = <span class="Constant">0x34</span><span class="Delimiter">;</span> -<span id="L136" class="LineNr">136 </span> emit<span class="Delimiter">(</span>e_phoff<span class="Delimiter">);</span> -<span id="L137" class="LineNr">137 </span> <span class="Comment">// e_shoff; unused</span> -<span id="L138" class="LineNr">138 </span> <span class="Normal">int</span> dummy32 = <span class="Constant">0</span><span class="Delimiter">;</span> -<span id="L139" class="LineNr">139 </span> emit<span class="Delimiter">(</span>dummy32<span class="Delimiter">);</span> -<span id="L140" class="LineNr">140 </span> <span class="Comment">// e_flags; unused</span> -<span id="L141" class="LineNr">141 </span> emit<span class="Delimiter">(</span>dummy32<span class="Delimiter">);</span> -<span id="L142" class="LineNr">142 </span> <span class="Comment">// e_ehsize</span> -<span id="L143" class="LineNr">143 </span> <span class="Normal">uint16_t</span> e_ehsize = <span class="Constant">0x34</span><span class="Delimiter">;</span> -<span id="L144" class="LineNr">144 </span> emit<span class="Delimiter">(</span>e_ehsize<span class="Delimiter">);</span> -<span id="L145" class="LineNr">145 </span> <span class="Comment">// e_phentsize</span> -<span id="L146" class="LineNr">146 </span> <span class="Normal">uint16_t</span> e_phentsize = <span class="Constant">0x20</span><span class="Delimiter">;</span> -<span id="L147" class="LineNr">147 </span> emit<span class="Delimiter">(</span>e_phentsize<span class="Delimiter">);</span> -<span id="L148" class="LineNr">148 </span> <span class="Comment">// e_phnum</span> -<span id="L149" class="LineNr">149 </span> <span class="Normal">uint16_t</span> e_phnum = <a href='001help.cc.html#L157'>SIZE</a><span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">);</span> -<span id="L150" class="LineNr">150 </span> emit<span class="Delimiter">(</span>e_phnum<span class="Delimiter">);</span> -<span id="L151" class="LineNr">151 </span> <span class="Comment">// e_shentsize</span> -<span id="L152" class="LineNr">152 </span> <span class="Normal">uint16_t</span> dummy16 = <span class="Constant">0x0</span><span class="Delimiter">;</span> -<span id="L153" class="LineNr">153 </span> emit<span class="Delimiter">(</span>dummy16<span class="Delimiter">);</span> -<span id="L154" class="LineNr">154 </span> <span class="Comment">// e_shnum</span> -<span id="L155" class="LineNr">155 </span> emit<span class="Delimiter">(</span>dummy16<span class="Delimiter">);</span> -<span id="L156" class="LineNr">156 </span> <span class="Comment">// e_shstrndx</span> -<span id="L157" class="LineNr">157 </span> emit<span class="Delimiter">(</span>dummy16<span class="Delimiter">);</span> -<span id="L158" class="LineNr">158 </span> -<span id="L159" class="LineNr">159 </span> <span class="Normal">uint32_t</span> p_offset = <span class="Comment">/*</span><span class="Comment">size of ehdr</span><span class="Comment">*/</span><span class="Constant">0x34</span> + <a href='001help.cc.html#L157'>SIZE</a><span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">)</span>*<span class="Constant">0x20</span><span class="Comment">/*</span><span class="Comment">size of each phdr</span><span class="Comment">*/</span><span class="Delimiter">;</span> -<span id="L160" class="LineNr">160 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < <a href='001help.cc.html#L157'>SIZE</a><span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span> -<span id="L161" class="LineNr">161 </span> <span class="SalientComment">//// phdr</span> -<span id="L162" class="LineNr">162 </span> <span class="Comment">// p_type</span> -<span id="L163" class="LineNr">163 </span> <span class="Normal">uint32_t</span> p_type = <span class="Constant">0x1</span><span class="Delimiter">;</span> -<span id="L164" class="LineNr">164 </span> emit<span class="Delimiter">(</span>p_type<span class="Delimiter">);</span> -<span id="L165" class="LineNr">165 </span> <span class="Comment">// p_offset</span> -<span id="L166" class="LineNr">166 </span> emit<span class="Delimiter">(</span>p_offset<span class="Delimiter">);</span> -<span id="L167" class="LineNr">167 </span> <span class="Comment">// p_vaddr</span> -<span id="L168" class="LineNr">168 </span> emit<span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span><a href='011run.cc.html#L105'>start</a><span class="Delimiter">);</span> -<span id="L169" class="LineNr">169 </span> <span class="Comment">// p_paddr</span> -<span id="L170" class="LineNr">170 </span> emit<span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span><a href='011run.cc.html#L105'>start</a><span class="Delimiter">);</span> -<span id="L171" class="LineNr">171 </span> <span class="Comment">// p_filesz</span> -<span id="L172" class="LineNr">172 </span> <span class="Normal">uint32_t</span> size = <a href='029translate.cc.html#L216'>size_of</a><span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">));</span> -<span id="L173" class="LineNr">173 </span> assert<span class="Delimiter">(</span>size < <a href='012elf.cc.html#L105'>SEGMENT_SIZE</a><span class="Delimiter">);</span> -<span id="L174" class="LineNr">174 </span> emit<span class="Delimiter">(</span>size<span class="Delimiter">);</span> -<span id="L175" class="LineNr">175 </span> <span class="Comment">// p_memsz</span> -<span id="L176" class="LineNr">176 </span> emit<span class="Delimiter">(</span>size<span class="Delimiter">);</span> -<span id="L177" class="LineNr">177 </span> <span class="Comment">// p_flags</span> -<span id="L178" class="LineNr">178 </span> <span class="Normal">uint32_t</span> p_flags = <span class="Delimiter">(</span>i == <span class="Constant">0</span><span class="Delimiter">)</span> ? <span class="Comment">/*</span><span class="Comment">r-x</span><span class="Comment">*/</span><span class="Constant">0x5</span> : <span class="Comment">/*</span><span class="Comment">rw-</span><span class="Comment">*/</span><span class="Constant">0x6</span><span class="Delimiter">;</span> <span class="Comment">// convention: only first segment is code</span> -<span id="L179" class="LineNr">179 </span> emit<span class="Delimiter">(</span>p_flags<span class="Delimiter">);</span> -<span id="L180" class="LineNr">180 </span> -<span id="L181" class="LineNr">181 </span> <span class="Comment">// p_align</span> -<span id="L182" class="LineNr">182 </span> <span class="Comment">// "As the system creates or augments a process image, it logically copies</span> -<span id="L183" class="LineNr">183 </span> <span class="Comment">// a file's segment to a virtual memory segment. When—and if— the system</span> -<span id="L184" class="LineNr">184 </span> <span class="Comment">// physically reads the file depends on the program's execution behavior,</span> -<span id="L185" class="LineNr">185 </span> <span class="Comment">// system load, and so on. A process does not require a physical page</span> -<span id="L186" class="LineNr">186 </span> <span class="Comment">// unless it references the logical page during execution, and processes</span> -<span id="L187" class="LineNr">187 </span> <span class="Comment">// commonly leave many pages unreferenced. Therefore delaying physical</span> -<span id="L188" class="LineNr">188 </span> <span class="Comment">// reads frequently obviates them, improving system performance. To obtain</span> -<span id="L189" class="LineNr">189 </span> <span class="Comment">// this efficiency in practice, executable and shared object files must</span> -<span id="L190" class="LineNr">190 </span> <span class="Comment">// have segment images whose file offsets and virtual addresses are</span> -<span id="L191" class="LineNr">191 </span> <span class="Comment">// congruent, modulo the page size." -- <a href="http://refspecs.linuxbase.org/elf/elf.pdf">http://refspecs.linuxbase.org/elf/elf.pdf</a> (page 95)</span> -<span id="L192" class="LineNr">192 </span> <span class="Normal">uint32_t</span> p_align = <span class="Constant">0x1000</span><span class="Delimiter">;</span> <span class="Comment">// default page size on linux</span> -<span id="L193" class="LineNr">193 </span> emit<span class="Delimiter">(</span>p_align<span class="Delimiter">);</span> -<span id="L194" class="LineNr">194 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>p_offset % p_align != p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span><a href='011run.cc.html#L105'>start</a> % p_align<span class="Delimiter">)</span> <span class="Delimiter">{</span> -<span id="L195" class="LineNr">195 </span> <a href='003trace.cc.html#L197'>raise</a> << <span class="Constant">"segment starting at 0x"</span> << <a href='010vm.cc.html#L239'>HEXWORD</a> << p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span><a href='011run.cc.html#L105'>start</a> << <span class="Constant">" is improperly aligned; alignment for p_offset "</span> << p_offset << <span class="Constant">" should be "</span> << <span class="Delimiter">(</span>p_offset % p_align<span class="Delimiter">)</span> << <span class="Constant">" but is "</span> << <span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L97'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span><a href='011run.cc.html#L105'>start</a> % p_align<span class="Delimiter">)</span> << <span class="cSpecial">'\n'</span> << <a href='003trace.cc.html#L215'>end</a><span class="Delimiter">();</span> -<span id="L196" class="LineNr">196 </span> <span class="Identifier">return</span><span class="Delimiter">;</span> -<span id="L197" class="LineNr">197 </span> <span class="Delimiter">}</span> -<span id="L198" class="LineNr">198 </span> -<span id="L199" class="LineNr">199 </span> <span class="Comment">// prepare for next segment</span> -<span id="L200" class="LineNr">200 </span> p_offset += size<span class="Delimiter">;</span> -<span id="L201" class="LineNr">201 </span> <span class="Delimiter">}</span> -<span id="L202" class="LineNr">202 </span><span class="Comment">#undef O</span> -<span id="L203" class="LineNr">203 </span><span class="Comment">#undef emit</span> -<span id="L204" class="LineNr">204 </span><span class="Delimiter">}</span> -<span id="L205" class="LineNr">205 </span> -<span id="L206" class="LineNr">206 </span><span class="Normal">void</span> <a href='029translate.cc.html#L206'>write_segment</a><span class="Delimiter">(</span><span class="Normal">const</span> segment& s<span class="Delimiter">,</span> ostream& out<span class="Delimiter">)</span> <span class="Delimiter">{</span> -<span id="L207" class="LineNr">207 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < <a href='001help.cc.html#L157'>SIZE</a><span class="Delimiter">(</span>s<span class="Delimiter">.</span><a href='011run.cc.html#L106'>lines</a><span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span> -<span id="L208" class="LineNr">208 </span> <span class="Normal">const</span> vector<word>& w = s<span class="Delimiter">.</span><a href='011run.cc.html#L106'>lines</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span><a href='011run.cc.html#L111'>words</a><span class="Delimiter">;</span> -<span id="L209" class="LineNr">209 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> j = <span class="Constant">0</span><span class="Delimiter">;</span> j < <a href='001help.cc.html#L157'>SIZE</a><span class="Delimiter">(</span>w<span class="Delimiter">);</span> ++j<span class="Delimiter">)</span> <span class="Delimiter">{</span> -<span id="L210" class="LineNr">210 </span> <span class="Normal">uint8_t</span> x = <a href='011run.cc.html#L222'>hex_byte</a><span class="Delimiter">(</span>w<span class="Delimiter">.</span>at<span class="Delimiter">(</span>j<span class="Delimiter">).</span><a href='011run.cc.html#L117'>data</a><span class="Delimiter">);</span> <span class="Comment">// we're done with metadata by this point</span> -<span id="L211" class="LineNr">211 </span> out<span class="Delimiter">.</span>write<span class="Delimiter">(</span><span class="Normal">reinterpret_cast</span><<span class="Normal">const</span> <span class="Normal">char</span>*><span class="Delimiter">(</span>&x<span class="Delimiter">),</span> <span class="Comment">/*</span><span class="Comment">sizeof(byte)</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">);</span> -<span id="L212" class="LineNr">212 </span> <span class="Delimiter">}</span> -<span id="L213" class="LineNr">213 </span> <span class="Delimiter">}</span> -<span id="L214" class="LineNr">214 </span><span class="Delimiter">}</span> -<span id="L215" class="LineNr">215 </span> -<span id="L216" class="LineNr">216 </span><span class="Normal">uint32_t</span> <a href='029translate.cc.html#L216'>size_of</a><span class="Delimiter">(</span><span class="Normal">const</span> segment& s<span class="Delimiter">)</span> <span class="Delimiter">{</span> -<span id="L217" class="LineNr">217 </span> <span class="Normal">uint32_t</span> sum = <span class="Constant">0</span><span class="Delimiter">;</span> -<span id="L218" class="LineNr">218 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < <a href='001help.cc.html#L157'>SIZE</a><span class="Delimiter">(</span>s<span class="Delimiter">.</span><a href='011run.cc.html#L106'>lines</a><span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> -<span id="L219" class="LineNr">219 </span> sum += <a href='001help.cc.html#L157'>SIZE</a><span class="Delimiter">(</span>s<span class="Delimiter">.</span><a href='011run.cc.html#L106'>lines</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span><a href='011run.cc.html#L111'>words</a><span class="Delimiter">);</span> -<span id="L220" class="LineNr">220 </span> <span class="Identifier">return</span> sum<span class="Delimiter">;</span> -<span id="L221" class="LineNr">221 </span><span class="Delimiter">}</span> -<span id="L222" class="LineNr">222 </span> -<span id="L223" class="LineNr">223 </span><span class="Delimiter">:(before "End Includes")</span> -<span id="L224" class="LineNr">224 </span><span class="Normal">using</span> std::ios<span class="Delimiter">;</span> -</pre> -</body> -</html> -<!-- vim: set foldmethod=manual : --> |