PNaCl documentation: link to ARM 32-bit sandbox internals

native_client_sdk/doc_generated/reference/sandbox_internals/arm-32-bit-sandbox.html

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 <section id="arm-32-bit-sandbox">
-<h1 id="arm-32-bit-sandbox">ARM 32-bit Sandbox</h1>
+<span id="id1"></span><h1 id="arm-32-bit-sandbox"><span id="id1"></span>ARM 32-bit Sandbox</h1>
 <p>Native Client for ARM is a sandboxing technology for running
 programs&#8212;even malicious ones&#8212;safely, on computers that use 32-bit
 ARM processors. The ARM sandbox is an extension of earlier work on
 Native Client for x86 processors. Security is provided with a low
 performance overhead of about 10% over regular ARM code, and as you&#8217;ll
 see in this document the sandbox model is beautifully simple, meaning
 that the trusted codebase is much easier to validate.</p>
 <p>As an implementation detail, the Native Client 32-bit ARM sandbox is
 currently used by Portable Native Client to execute code on 32-bit ARM
 machines in a safe manner. The portable bitcode contained in a <strong>pexe</strong>
 is translated to a 32-bit ARM <strong>nexe</strong> before execution. This may change
 at a point in time: Portable Native Client doesn&#8217;t necessarily need this
 sandbox to execute code on ARM. Note that the Portable Native Client
 compiler itself is also untrusted: it too runs in the ARM sandbox
 described in this document.</p>
 <p>On this page, we describe how Native Client works on 32-bit ARM. We
 assume no prior knowledge about the internals of Native Client, on x86
 or any other architecture, but we do assume some familiarity with
 assembly languages in general.</p>
 <div class="contents local" id="contents" style="display: none">
 <ul class="small-gap">
-<li><p class="first"><a class="reference internal" href="#an-introduction-to-the-arm-architecture" id="id2">An Introduction to the ARM Architecture</a></p>
+<li><p class="first"><a class="reference internal" href="#an-introduction-to-the-arm-architecture" id="id3">An Introduction to the ARM Architecture</a></p>
 <ul class="small-gap">
-<li><a class="reference internal" href="#about-arm-and-armv7-a" id="id3">About ARM and ARMv7-A</a></li>
-<li><a class="reference internal" href="#arm-programmer-s-model" id="id4">ARM Programmer&#8217;s Model</a></li>
+<li><a class="reference internal" href="#about-arm-and-armv7-a" id="id4">About ARM and ARMv7-A</a></li>
+<li><a class="reference internal" href="#arm-programmer-s-model" id="id5">ARM Programmer&#8217;s Model</a></li>
 </ul>
 </li>
-<li><p class="first"><a class="reference internal" href="#the-native-client-approach" id="id5">The Native Client Approach</a></p>
+<li><p class="first"><a class="reference internal" href="#the-native-client-approach" id="id6">The Native Client Approach</a></p>
 <ul class="small-gap">
-<li><p class="first"><a class="reference internal" href="#nacl-arm-pure-software-fault-isolation" id="id6">NaCl/ARM: Pure Software Fault Isolation</a></p>
+<li><p class="first"><a class="reference internal" href="#nacl-arm-pure-software-fault-isolation" id="id7">NaCl/ARM: Pure Software Fault Isolation</a></p>
 <ul class="small-gap">
-<li><a class="reference internal" href="#load-and-store" id="id7"><em>Load</em> and <em>Store</em></a></li>
-<li><a class="reference internal" href="#the-stack-pointer-thread-pointer-and-program-counter" id="id8">The Stack Pointer, Thread Pointer, and Program Counter</a></li>
-<li><a class="reference internal" href="#indirect-branch" id="id9"><em>Indirect Branch</em></a></li>
-<li><a class="reference internal" href="#literal-pools-and-data-bundles" id="id10">Literal Pools and Data Bundles</a></li>
+<li><a class="reference internal" href="#load-and-store" id="id8"><em>Load</em> and <em>Store</em></a></li>
+<li><a class="reference internal" href="#the-stack-pointer-thread-pointer-and-program-counter" id="id9">The Stack Pointer, Thread Pointer, and Program Counter</a></li>
+<li><a class="reference internal" href="#indirect-branch" id="id10"><em>Indirect Branch</em></a></li>
+<li><a class="reference internal" href="#literal-pools-and-data-bundles" id="id11">Literal Pools and Data Bundles</a></li>
 </ul>
 </li>
-<li><p class="first"><a class="reference internal" href="#trampolines-and-memory-layout" id="id11">Trampolines and Memory Layout</a></p>
+<li><p class="first"><a class="reference internal" href="#trampolines-and-memory-layout" id="id12">Trampolines and Memory Layout</a></p>
 <ul class="small-gap">
-<li><a class="reference internal" href="#memory-map" id="id12">Memory Map</a></li>
-<li><a class="reference internal" href="#inside-a-trampoline" id="id13">Inside a Trampoline</a></li>
+<li><a class="reference internal" href="#memory-map" id="id13">Memory Map</a></li>
+<li><a class="reference internal" href="#inside-a-trampoline" id="id14">Inside a Trampoline</a></li>
 </ul>
 </li>
-<li><p class="first"><a class="reference internal" href="#loose-ends" id="id14">Loose Ends</a></p>
+<li><p class="first"><a class="reference internal" href="#loose-ends" id="id15">Loose Ends</a></p>
 <ul class="small-gap">
-<li><a class="reference internal" href="#forbidden-instructions" id="id15">Forbidden Instructions</a></li>
-<li><a class="reference internal" href="#coprocessors" id="id16">Coprocessors</a></li>
-<li><a class="reference internal" href="#validator-code" id="id17">Validator Code</a></li>
+<li><a class="reference internal" href="#forbidden-instructions" id="id16">Forbidden Instructions</a></li>
+<li><a class="reference internal" href="#coprocessors" id="id17">Coprocessors</a></li>
+<li><a class="reference internal" href="#validator-code" id="id18">Validator Code</a></li>
 </ul>
 </li>
 </ul>
 </li>
 </ul>
 
 </div><section id="an-introduction-to-the-arm-architecture">
 <h2 id="an-introduction-to-the-arm-architecture">An Introduction to the ARM Architecture</h2>
 <p>In this section, we summarize the relevant parts of the ARM processor
 architecture.</p>
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 <h4 id="validator-code">Validator Code</h4>
 <p>By now you&#8217;re itching to see the sandbox validator&#8217;s code and dissect
 it. You&#8217;ll have a disapointing read: at less that 500 lines of code
 <a class="reference external" href="http://src.chromium.org/viewvc/native_client/trunk/src/native_client/src/trusted/validator_arm/validator.cc">validator.cc</a>
 is quite simple to understand and much shorter than this document. It&#8217;s
 of course dependent on the <a class="reference external" href="http://src.chromium.org/viewvc/native_client/trunk/src/native_client/src/trusted/validator_arm/armv7.table">ARMv7 instruction table definition</a>,
 which teaches it about the ARMv7 instruction set.</p>
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