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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>syscall_get_arguments</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="ch03s03.html" title="System Call Tracing" /><link rel="prev" href="re36.html" title="syscall_set_return_value" /><link rel="next" href="re38.html" title="syscall_set_arguments" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>syscall_get_arguments</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re36.html">Prev</a> </td><th width="60%" align="center"><code class="filename">System Call Tracing</code></th><td width="20%" align="right"> <a accesskey="n" href="re38.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="syscall_get_arguments"><a id="API-syscall-get-arguments"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>syscall_get_arguments —
extract system call parameter values
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">syscall_get_arguments </b>(</code></td><td>struct task_struct * <var class="pdparam">task</var>, </td></tr><tr><td> </td><td>struct pt_regs * <var class="pdparam">regs</var>, </td></tr><tr><td> </td><td>unsigned int <var class="pdparam">i</var>, </td></tr><tr><td> </td><td>unsigned int <var class="pdparam">n</var>, </td></tr><tr><td> </td><td>unsigned long * <var class="pdparam">args</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id3104596"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>task</code></em></span></dt><dd><p>
task of interest, must be blocked
</p></dd><dt><span class="term"><em class="parameter"><code>regs</code></em></span></dt><dd><p>
<code class="function">task_pt_regs</code> of <em class="parameter"><code>task</code></em>
</p></dd><dt><span class="term"><em class="parameter"><code>i</code></em></span></dt><dd><p>
argument index [0,5]
</p></dd><dt><span class="term"><em class="parameter"><code>n</code></em></span></dt><dd><p>
number of arguments; n+i must be [1,6].
</p></dd><dt><span class="term"><em class="parameter"><code>args</code></em></span></dt><dd><p>
array filled with argument values
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id3104698"></a><h2>Description</h2><p>
Fetches <em class="parameter"><code>n</code></em> arguments to the system call starting with the <em class="parameter"><code>i</code></em>'th argument
(from 0 through 5). Argument <em class="parameter"><code>i</code></em> is stored in <em class="parameter"><code>args</code></em>[0], and so on.
An arch inline version is probably optimal when <em class="parameter"><code>i</code></em> and <em class="parameter"><code>n</code></em> are constants.
</p><p>
It's only valid to call this when <em class="parameter"><code>task</code></em> is stopped for tracing on
entry to a system call, due to <code class="constant">TIF_SYSCALL_TRACE</code> or <code class="constant">TIF_SYSCALL_AUDIT</code>.
It's invalid to call this with <em class="parameter"><code>i</code></em> + <em class="parameter"><code>n</code></em> > 6; we only support system calls
taking up to 6 arguments.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re36.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch03s03.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re38.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>syscall_set_return_value</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_set_arguments</span></td></tr></table></div></body></html>
