Re: [DynInst_API:] Inserting multiple snippets at an insertion point?

[Bill Williams <bill@xxxxxxxxxxx>]

On 07/21/2014 11:45 AM, Wayne Motycka wrote:
> I've been trying to find ways to instrument the edges in the Dyninst CFG
> but instrumenting the back edge from a system library call, e.g. calling
> printf(), doesn't give insertion points that seem reasonable/valid (the
> insertion point addresses given by getExitPoints() and getAllPoints()
> appears to be out of the local programs address ranges.)
It's possible (and if memory serves, it's likely) that when you're 
inserting edge instrumentation, its instpoint address will be somewhere 
in relocated code and will not correspond neatly to an original address. 
(This is particularly true for call/return edges, as a particular 
interprocedural edge doesn't live anywhere in the original binary.) We 
*should* hand back NULL instpoints if they're really unusable.
> So, I'm thinking of moving that edge instrumenting code block into the
> edge that connects the calling block to the subsequent block along with
> the instrumenting code for that connecting edge, effectively marking that
> connecting edge as both the return path from the printf() system call and
> the inter-block connecting edge (which is EdgeTypeEnum type of "post-call
> fallthrough")
This is also a reasonable approach, and call fallthrough edges exist for 
this sort of simplification.
> My question is if it is possible to insert two snippets referencing calls
> to my edge marking library routine?
Yes, it's valid to insert multiple snippets at the same instrumentation 
point; the "before/after" parameter to insertSnippet governs the 
relative order of execution, if that's relevant to you.
> Thanks,
> Wayne Motycka
> E2 Lab @ Univ. of Nebraska - Lincoln
>
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--
--bw

Bill Williams
Paradyn Project
bill@xxxxxxxxxxx