Re: [DynInst_API:] Stackwalking in a mutatee

[Matthew LeGendre <legendre1@xxxxxxxx>]

It's been several years since I tried doing 1st-party stackwalks from an 
instrumented mutatee and things may have changed.  But the last time I did 
this you could add a call to
  BPatch::setInstrStackFrames(true);

before you insert instrumentation.  This would cause Dyninst to generate 
stack frames around generated instrumentation.  That adds runtime 
overhead, but also gives a stack walker sufficient information to walk out 
of the instrumentation.

I believe there's also efforts underway to have Dyninst start updating 
existing DWARF stack unwinding information as it instruments and relocates 
code.  But I'm not sure where those efforts stand or when they'd appear in 
a released Dyninst.  Someone from the Dyninst team would have to comment.
-Matt

On Wed, 28 Aug 2013, Marc Brünink wrote:
> Dear all,
>
> short version:
> What is the appropriate way to walk the stack in a mutatee?
>
> long version:
> StackwalkerAPI implements basic stack walking. Some code in Dyninst 
> implements the additional tweaks necessary to handle the complexity added by 
> instrumentation. Thus, we can still perform a third party stackwalk of 
> instrumented code.
> But how do I perform a first party stackwalk in the mutatee? The problem is 
> that only the mutator knows about all this additional Dyninst features, e.g. 
> which code got relocated, etc.
> I suppose this is a very common problem. However, at the moment I fail to 
> find a nice, clean, and easy way to walk the stack in the mutatee.
> Before I dive into this in more detail, let me ask a simple question:
>
> Is there an obvious way to walk the stack in the mutatee which I just don't 
> know about? Or do I have to manually make sure the FrameSteppers etc. in my 
> mutatee are up-to-date?
> Marc
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