Re: [DynInst_API:] Is the dynamic mode dyninst disable ptrace?

[Matthew LeGendre <legendre1@xxxxxxxx>]

On Tue, 17 Feb 2015, Bill Williams wrote:
> On 02/17/2015 07:05 AM, Xi Chen wrote:
> > Hi,
> >    I recently try to debug the dynamic mode dyninst because I found the
> > result is inconsistent with the static rewrite. I basically want to
> > attach to mutatee process, and see how the instrumentation code be
> > executed. However, when I do that in GDB, it tell me the ptrace
> > operation is not permitted (I have teh yama/ptrace_scope as 0). I wonder
> > if there are any way I can attach to the mutatee's address space and
> > debug there?
> Not without detaching your mutator first; ptrace only allows one debugger at 
> a time to be attached.
> You can, however, use breakpoint snippets and the stack walking interface in 
> BPatch_process for programmatic debugging. You can also enable 
> DYNINST_DEBUG_RELOC and/or DYNINST_DEBUG_SPRINGBOARD in your environment to 
> see what, exactly, we're generating for relocated/instrumented code and for 
> branches that lead to it, respectively.
Core files can also be a convenient way to debug generated 
instrumentation.  Just send the process a SIGSEGV after instrumenting. 
You can't walk through the code as it runs, but with gdb's 'disass' 
command you can dump the assembly showing what was generated and modified.
-Matt