docs: Sync with upstream

Author: danobi

docs/master.html

@@ -1862,6 +1862,11 @@ <h2 id="_functions">Functions</h2>
 <td class="tableblock halign-left valign-top"><p class="tableblock">Async</p></td>
 </tr>
 <tr>
+<td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#functions-len"><code>len</code></a></p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Count ustack/kstack frames</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Sync</p></td>
+</tr>
+<tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#functions-macaddr"><code>macaddr</code></a></p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">Convert MAC address data</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">Sync</p></td>
@@ -2371,6 +2376,24 @@ <h3 id="functions-ksym">ksym</h3>
 </div>
 </div>
 <div class="sect2">
+<h3 id="functions-len">len</h3>
+<div class="ulist">
+<div class="title">variants</div>
+<ul>
+<li>
+<p><code>int64 len(ustack stack)</code></p>
+</li>
+<li>
+<p><code>int64 len(kstack stack)</code></p>
+</li>
+</ul>
+</div>
+<div class="paragraph">
+<p>Retrieve the depth (measured in # of frames) of the call stack
+specified by <code>stack</code>.</p>
+</div>
+</div>
+<div class="sect2">
 <h3 id="functions-macaddr">macaddr</h3>
 <div class="ulist">
 <div class="title">variants</div>

src/docs/master.adoc

@@ -21,9 +21,9 @@ When _FILENAME_ is "_-_", bpftrace will read program code from stdin.
 
 == Description
 
-bpftrace is a high-level tracing language for Linux. bpftrace uses LLVM as 
-a backend to compile scripts to eBPF-bytecode and makes use of libbpf and bcc 
-for interacting with the Linux BPF subsystem, as well as existing Linux 
+bpftrace is a high-level tracing language for Linux. bpftrace uses LLVM as
+a backend to compile scripts to eBPF-bytecode and makes use of libbpf and bcc
+for interacting with the Linux BPF subsystem, as well as existing Linux
 tracing capabilities.
 
 == Examples
@@ -1334,6 +1334,10 @@ Tracing block I/O sizes > 0 bytes
 | Resolve kernel address
 | Async
 
+| <<functions-len, `len`>>
+| Count ustack/kstack frames
+| Sync
+
 | <<functions-macaddr, `macaddr`>>
 | Convert MAC address data
 | Sync
@@ -1713,6 +1717,16 @@ kprobe:do_nanosleep
  */
 ----
 
+[#functions-len]
+=== len
+
+.variants
+* `int64 len(ustack stack)`
+* `int64 len(kstack stack)`
+
+Retrieve the depth (measured in # of frames) of the call stack
+specified by `stack`.
+
 [#functions-macaddr]
 === macaddr