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| author | Kartik Agaram <vc@akkartik.com> | 2021-03-23 17:31:08 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2021-03-23 17:31:08 -0700 |
| commit | 3350c34a74844e21ea69077e01efff3bae64bdcd (patch) | |
| tree | fa06ba58542297d1cff6b78958d4547a40a25d21 /html/linux/313index-bounds-check.subx.html | |
| parent | 62a244211024a8367332541c571621883c05bcce (diff) | |
| download | mu-3350c34a74844e21ea69077e01efff3bae64bdcd.tar.gz | |
.
Diffstat (limited to 'html/linux/313index-bounds-check.subx.html')
| -rw-r--r-- | html/linux/313index-bounds-check.subx.html | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/html/linux/313index-bounds-check.subx.html b/html/linux/313index-bounds-check.subx.html new file mode 100644 index 00000000..fbbd8000 --- /dev/null +++ b/html/linux/313index-bounds-check.subx.html @@ -0,0 +1,148 @@ +<!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 - linux/313index-bounds-check.subx</title> +<meta name="Generator" content="Vim/8.1"> +<meta name="plugin-version" content="vim8.1_v1"> +<meta name="syntax" content="none"> +<meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy="> +<meta name="colorscheme" content="minimal-light"> +<style type="text/css"> +<!-- +pre { white-space: pre-wrap; 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; } +.subxS1Comment { color: #0000af; } +.LineNr { } +.Constant { color: #008787; } +.SpecialChar { color: #d70000; } +.subxMinorFunction { color: #875f5f; } +.CommentedCode { color: #8a8a8a; } +--> +</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; + } + var 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/main/linux/313index-bounds-check.subx'>https://github.com/akkartik/mu/blob/main/linux/313index-bounds-check.subx</a> +<pre id='vimCodeElement'> +<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># Helper to check an array's bounds, and to abort if they're violated.</span> +<span id="L2" class="LineNr"> 2 </span><span class="subxComment"># Really only intended to be called from code generated by mu.subx.</span> +<span id="L3" class="LineNr"> 3 </span> +<span id="L4" class="LineNr"> 4 </span>== code +<span id="L5" class="LineNr"> 5 </span> +<span id="L6" class="LineNr"> 6 </span><span class="subxMinorFunction">__check-mu-array-bounds</span>: <span class="subxComment"># index: int, elem-size: int, arr-size: int, function-name: (addr array byte), array-name: (addr array byte)</span> +<span id="L7" class="LineNr"> 7 </span> <span class="subxS1Comment"># . prologue</span> +<span id="L8" class="LineNr"> 8 </span> 55/push-ebp +<span id="L9" class="LineNr"> 9 </span> 89/<- %ebp 4/r32/esp +<span id="L10" class="LineNr">10 </span> <span class="subxS1Comment"># . save registers</span> +<span id="L11" class="LineNr">11 </span> 50/push-eax +<span id="L12" class="LineNr">12 </span> 51/push-ecx +<span id="L13" class="LineNr">13 </span> 52/push-edx +<span id="L14" class="LineNr">14 </span> <span class="subxS1Comment"># . not bothering saving ebx; it's only clobbered if we're going to abort</span> +<span id="L15" class="LineNr">15 </span> <span class="subxComment"># ecx = arr-size</span> +<span id="L16" class="LineNr">16 </span> 8b/-> *(ebp+0x10) 1/r32/ecx +<span id="L17" class="LineNr">17 </span> <span class="subxComment"># var overflow/edx: int = 0</span> +<span id="L18" class="LineNr">18 </span> ba/copy-to-edx 0/imm32 +<span id="L19" class="LineNr">19 </span> <span class="subxComment"># var offset/eax: int = index * elem-size</span> +<span id="L20" class="LineNr">20 </span> 8b/-> *(ebp+8) 0/r32/eax +<span id="L21" class="LineNr">21 </span> f7 4/subop/multiply-eax-with *(ebp+0xc) +<span id="L22" class="LineNr">22 </span> <span class="subxComment"># check for overflow</span> +<span id="L23" class="LineNr">23 </span> 81 7/subop/compare %edx 0/imm32 +<span id="L24" class="LineNr">24 </span> 0f 85/jump-if-!= <a href='313index-bounds-check.subx.html#L6'>__check-mu-array-bounds</a>:overflow/disp32 +<span id="L25" class="LineNr">25 </span> <span class="subxComment"># check bounds</span> +<span id="L26" class="LineNr">26 </span> 39/compare %eax 1/r32/ecx +<span id="L27" class="LineNr">27 </span> 0f 82/jump-if-unsigned< $__check-mu-array-bounds:end/disp32 <span class="subxComment"># negative index should always abort</span> +<span id="L28" class="LineNr">28 </span> <span class="subxComment"># abort if necessary</span> +<span id="L29" class="LineNr">29 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> <span class="Constant">"fn "</span>) +<span id="L30" class="LineNr">30 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> *(ebp+0x14)) +<span id="L31" class="LineNr">31 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> <span class="Constant">": offset "</span>) +<span id="L32" class="LineNr">32 </span> (<a href='117write-int-hex.subx.html#L288'>write-int32-hex-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> %eax) +<span id="L33" class="LineNr">33 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> <span class="Constant">" is too large for array '"</span>) +<span id="L34" class="LineNr">34 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> *(ebp+0x18)) +<span id="L35" class="LineNr">35 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> <span class="Constant">"'\n"</span>) +<span id="L36" class="LineNr">36 </span> (<a href='115write-byte.subx.html#L81'>flush</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span>) +<span id="L37" class="LineNr">37 </span> <span class="subxComment"># exit(1)</span> +<span id="L38" class="LineNr">38 </span> bb/copy-to-ebx 1/imm32 +<span id="L39" class="LineNr">39 </span> e8/call <a href='000init.subx.html#L18'>syscall_exit</a>/disp32 +<span id="L40" class="LineNr">40 </span> <span class="subxComment"># never gets here</span> +<span id="L41" class="LineNr">41 </span><span class="Constant">$__check-mu-array-bounds:end</span>: +<span id="L42" class="LineNr">42 </span> <span class="subxS1Comment"># . restore registers</span> +<span id="L43" class="LineNr">43 </span> 5a/pop-to-edx +<span id="L44" class="LineNr">44 </span> 59/pop-to-ecx +<span id="L45" class="LineNr">45 </span> 58/pop-to-eax +<span id="L46" class="LineNr">46 </span> <span class="subxS1Comment"># . epilogue</span> +<span id="L47" class="LineNr">47 </span> 89/<- %esp 5/r32/ebp +<span id="L48" class="LineNr">48 </span> 5d/pop-to-ebp +<span id="L49" class="LineNr">49 </span> c3/return +<span id="L50" class="LineNr">50 </span> +<span id="L51" class="LineNr">51 </span><span class="subxMinorFunction">__check-mu-array-bounds:overflow</span>: +<span id="L52" class="LineNr">52 </span> <span class="subxComment"># "fn " function-name ": offset to array '" array-name "' overflowed 32 bits\n"</span> +<span id="L53" class="LineNr">53 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> <span class="Constant">"fn "</span>) +<span id="L54" class="LineNr">54 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> *(ebp+0x14)) +<span id="L55" class="LineNr">55 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> <span class="Constant">": offset to array '"</span>) +<span id="L56" class="LineNr">56 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> *(ebp+0x18)) +<span id="L57" class="LineNr">57 </span> (<a href='116write-buffered.subx.html#L8'>write-buffered</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span> <span class="Constant">"' overflowed 32 bits\n"</span>) +<span id="L58" class="LineNr">58 </span> (<a href='115write-byte.subx.html#L81'>flush</a> <span class="SpecialChar"><a href='116write-buffered.subx.html#L209'>Stderr</a></span>) +<span id="L59" class="LineNr">59 </span> <span class="subxComment"># exit(1)</span> +<span id="L60" class="LineNr">60 </span> bb/copy-to-ebx 1/imm32 +<span id="L61" class="LineNr">61 </span> e8/call <a href='000init.subx.html#L18'>syscall_exit</a>/disp32 +<span id="L62" class="LineNr">62 </span> <span class="subxComment"># never gets here</span> +<span id="L63" class="LineNr">63 </span> +<span id="L64" class="LineNr">64 </span><span class="subxComment"># potential alternative</span> +<span id="L65" class="LineNr">65 </span> +<span id="L66" class="LineNr">66 </span><span class="CommentedCode">#? __bounds-check: # msg: (addr array byte)</span> +<span id="L67" class="LineNr">67 </span><span class="CommentedCode">#? (write-buffered Stderr "abort: array bounds exceeded in fn ")</span> +<span id="L68" class="LineNr">68 </span><span class="CommentedCode">#? 8b/-> *(esp+4) 0/r32/eax # we're going to abort, so just clobber away</span> +<span id="L69" class="LineNr">69 </span><span class="CommentedCode">#? (write-buffered Stderr %eax)</span> +<span id="L70" class="LineNr">70 </span><span class="CommentedCode">#? (write-buffered Stderr Newline)</span> +<span id="L71" class="LineNr">71 </span><span class="CommentedCode">#? # exit(1)</span> +<span id="L72" class="LineNr">72 </span><span class="CommentedCode">#? bb/copy-to-ebx 1/imm32</span> +<span id="L73" class="LineNr">73 </span><span class="CommentedCode">#? e8/call syscall_exit/disp32</span> +<span id="L74" class="LineNr">74 </span> +<span id="L75" class="LineNr">75 </span><span class="subxComment"># to be called as follows:</span> +<span id="L76" class="LineNr">76 </span><span class="subxComment"># var/reg <- index arr/rega: (addr array T), idx/regi: int</span> +<span id="L77" class="LineNr">77 </span><span class="subxComment"># | if size-of(T) is 1, 2, 4 or 8</span> +<span id="L78" class="LineNr">78 </span><span class="subxComment"># => # temporarily save array size to reg to check bounds</span> +<span id="L79" class="LineNr">79 </span><span class="subxComment"># "8b/-> *" rega " " reg "/r32"</span> +<span id="L80" class="LineNr">80 </span><span class="subxComment"># "c1/shift 5/subop/right %" reg " " log2(size-of(T)) "/imm32"</span> +<span id="L81" class="LineNr">81 </span><span class="subxComment"># "3b/compare " reg "/r32 *" rega</span> +<span id="L82" class="LineNr">82 </span><span class="subxComment"># "68/push \"" function "\"/imm32" # pass function name to error message</span> +<span id="L83" class="LineNr">83 </span><span class="subxComment"># "0f 8d/jump-if->= __bounds_check/disp32"</span> +<span id="L84" class="LineNr">84 </span><span class="subxComment"># "81 0/subop/add %esp 4/imm32" # drop function name</span> +<span id="L85" class="LineNr">85 </span><span class="subxComment"># # actually save the index addr in reg</span> +<span id="L86" class="LineNr">86 </span><span class="subxComment"># "8d/copy-address *(" rega "+" regi "<<" log2(size-of(T)) "+4) " reg "/r32"</span> +</pre> +</body> +</html> +<!-- vim: set foldmethod=manual : --> |