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<div class="moz-cite-prefix">On 12/10/15 12:06 AM, Andres Torres
Garcia via llvm-dev wrote:<br>
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<p>Hi,</p>
<p><br>
</p>
<p>I want to use LLVM to make a dynamic fault injection. My
primary goal is to modify the value of a particular register
in a particular instruction and do, for example, bit
flipping on that register.</p>
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<br>
By dynamic, do you mean that you want to change which faults are
injected while the program is running, or is it sufficient to
recompile the program and rerun it when you want to inject new
faults?<br>
<br>
Also, are you wanting to inject faults at the LLVM IR level, or do
you want to inject faults after the program's machine code has been
generated (e.g., you want to inject faults into a particular
register)?<br>
<br>
The answers to these questions will determine whether you need to
write an LLVM IR pass or an LLVM MachineFunction pass (or whether
you really want to be modifying a dynamic binary translator like
QEMU/Valgrind instead of using LLVM).<br>
<br>
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<p><br>
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<p>I've studying some tutorials and codes about LLVM but I'm
still not sure how to begin with. I know that I need to
program a LLVM pass that iterates over blocks and check
which instruction modify to later check which operand in
that instruction modify. Is that the correct?</p>
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<br>
I think the first three documents to read are:<br>
<br>
1) How to Write an LLVM Pass<br>
2) The LLVM Programmer's Manual<br>
3) The LLVM Language Reference Manual<br>
<br>
The first document explains how to add a new analysis/transform to
the compiler. The second explains some of the utility functions and
idioms that you will see in existing LLVM code. The third describes
(in gory detail) the LLVM IR instruction set.<br>
<br>
Regards,<br>
<br>
John Criswell<br>
<br>
<br>
<pre class="moz-signature" cols="72">--
John Criswell
Assistant Professor
Department of Computer Science, University of Rochester
<a class="moz-txt-link-freetext" href="http://www.cs.rochester.edu/u/criswell">http://www.cs.rochester.edu/u/criswell</a></pre>
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