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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_nr</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="ch03s03.html" title="System Call Tracing" /><link rel="next" href="re33.html" title="syscall_rollback" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>syscall_get_nr</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch03s03.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="re33.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="syscall_get_nr"><a id="API-syscall-get-nr"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>syscall_get_nr —
find what system call a task is executing
</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">int <b class="fsfunc">syscall_get_nr </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><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2896493"></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></dl></div></div><div class="refsect1" title="Description"><a id="id2896546"></a><h2>Description</h2><p>
If <em class="parameter"><code>task</code></em> is executing a system call or is at system call
tracing about to attempt one, returns the system call number.
If <em class="parameter"><code>task</code></em> is not executing a system call, i.e. it's blocked
inside the kernel for a fault or signal, returns -1.
</p><p>
Note this returns int even on 64-bit machines. Only 32 bits of
system call number can be meaningful. If the actual arch value
is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
</p><p>
It's only valid to call this when <em class="parameter"><code>task</code></em> is known to be blocked.
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