Re: [DynInst_API:] Inserting x86 traps before points of interest

[Yasser Shalabi <yassershalabi@xxxxxxxxx>]

Yeah there is a better way. LLVM compiler pass :P

But what I am compiling uses GCC specific features unimplemented in
LLVM... so my pass is useless. And GCC backend is not something I feel
like learning right now...

Okay. So after setting it the program runs to termination. But only
one int3 is inserted, even when I add each point in the program to the
vector of points to instrument.

Also, there is a huge new section being inserted into the binary.

Thoughts?

Yasser

On Mon, Oct 26, 2015 at 1:25 PM, Bill Williams <bill@xxxxxxxxxxx> wrote:
> On 10/26/2015 01:11 PM, Yasser Shalabi wrote:
>
> I need int3 to trigger the hypervisor. I am running in virtualized settings.
> I want to statically instrument the binary at points of interest to trigger
> these virtualization exits.
>
>
> Makes sense, though I have a nagging feeling there may be a better way to do
> this.
>
> Anyhow. Breakpoint snippets go through our runtime library's
> platform-independent breakpoint function; what you're seeing makes sense
> (possibly) if your DYNINSTAPI_RT_LIB environment variable is not set. We
> should be checking that before we blithely try to insert calls into the RT
> lib, though...
>
> I know rewriter mode on Linux can generally talk to the RT lib, though, and
> rewriter mode on Windows is still not working (it's on my ever-expanding
> TODO list, but it's not there yet). So I would guess it's either platform or
> environment problems.
>
> --bw
>
>
> On Mon, Oct 26, 2015, 1:07 PM Bill Williams <bill@xxxxxxxxxxx> wrote:
>>
>> On 10/26/2015 01:00 PM, Yasser Shalabi wrote:
>> > Thanks for the quick reply bill!
>> >
>> > When I try:
>> >
>> >      app->insertSnippet(BPatch_breakPointExpr(),
>> > instrumentation_points);
>> >      BPatch_binaryEdit *appBin = dynamic_cast<BPatch_binaryEdit *>(app);
>> >      appBin->writeFile(newName);
>> >
>> > I get an assertion failure:
>> >
>> > DyninstAPI-9.0.3/dyninstAPI/src/ast.C:2072: virtual bool
>> > AstCallNode::initRegisters(codeGen&): Assertion `callee' failed.
>> >
>> > Any tips on how to approach?
>> ...what function is it trying to insert a call to? (A call stack from
>> gdb should be sufficient.) And what platform are you on?
>>
>> In any event, a breakpointexpr may well not do the right thing in
>> rewriter mode; it's intended for use when Dyninst is serving as a live
>> debugger for the process. What's the bigger picture? What do you want to
>> accomplish when these traps are hit?
>>
>> On Mon, Oct 26, 2015 at 11:11 AM, Bill Williams <bill@xxxxxxxxxxx> wrote:
>> >> On 10/26/2015 10:33 AM, Yasser Shalabi wrote:
>> >>
>> >> I want to insert int3 before points of interest.I have collected these
>> >> points using Dyninst. Any pointers on which parts of the API to
>> >> instrument
>> >> these points with int3 instructions?
>> >>
>> >> A BPatch_breakpointExpr should do the trick.
>> >>
>> >> Thanks!
>> >> Yasser
>> >>
>> >>
>> >>
>> >> _______________________________________________
>> >> Dyninst-api mailing list
>> >> Dyninst-api@xxxxxxxxxxx
>> >> https://lists.cs.wisc.edu/mailman/listinfo/dyninst-api
>> >>
>> >>
>>
>