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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>System Call Tracing</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="The utrace User Debugging Infrastructure" /><link rel="up" href="ch03.html" title="Chapter 3. Machine State" /><link rel="prev" href="re31.html" title="task_current_syscall" /><link rel="next" href="re32.html" title="syscall_get_nr" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><code class="filename">System Call Tracing</code></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re31.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Machine State</th><td width="20%" align="right"> <a accesskey="n" href="re32.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="System Call Tracing"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="syscall"></a><code class="filename">System Call Tracing</code></h2></div></div></div><div class="toc"><dl><dt><span class="refentrytitle"><a href="re32.html"><span>syscall_get_nr</span></a></span><span class="refpurpose"> —
find what system call a task is executing
</span></dt><dt><span class="refentrytitle"><a href="re33.html"><span>syscall_rollback</span></a></span><span class="refpurpose"> —
roll back registers after an aborted system call
</span></dt><dt><span class="refentrytitle"><a href="re34.html"><span>syscall_get_error</span></a></span><span class="refpurpose"> —
check result of traced system call
</span></dt><dt><span class="refentrytitle"><a href="re35.html"><span>syscall_get_return_value</span></a></span><span class="refpurpose"> —
get the return value of a traced system call
</span></dt><dt><span class="refentrytitle"><a href="re36.html"><span>syscall_set_return_value</span></a></span><span class="refpurpose"> —
change the return value of a traced system call
</span></dt><dt><span class="refentrytitle"><a href="re37.html"><span>syscall_get_arguments</span></a></span><span class="refpurpose"> —
extract system call parameter values
</span></dt><dt><span class="refentrytitle"><a href="re38.html"><span>syscall_set_arguments</span></a></span><span class="refpurpose"> —
change system call parameter value
</span></dt></dl></div><p>
The arch API for system call information is declared in
<code class="filename"><asm/syscall.h></code>.
Each of these calls can be used only at system call entry tracing,
or can be used only at system call exit and the subsequent safe points
before returning to user mode.
At system call entry tracing means either during a
<em class="structfield"><code>report_syscall_entry</code></em> callback,
or any time after that callback has returned <code class="constant">UTRACE_STOP</code>.
</p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re31.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch03.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re32.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>task_current_syscall</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>syscall_get_nr</span></td></tr></table></div></body></html>
