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Re: [RFC][PATCH 1/4] kprobe-based symbol resolution for stap-translator


Prerna Saxena <prerna@linux.vnet.ibm.com> writes:

> Here's a set of patches which enable the stap-translator to utilize
> kprobes for resolving function addresses.  ( Similar to James
> Bottomley's patch sent out last july ) In place of resolving probe
> points in semantic pass (Pass 2 ) by consulting vmlinux/debuginfo,
> this approach defers symbol resolution to the generated kprobes
> module. [...]

I remain unfond of this approach for a variety of reasons.  Perhaps the
best thing is to add this as a separate probe point family entirely,
like    kernel.kprobe("name")   Then there will be no expectation
that wildcards or $-variables should work, nor would there be any
disruption to the dwarf-based code currently in the translator.


> In its present form, it is capable of probing function entry & returns
> (non-inlines). It does /*not*/ support :
>    *  a wildcard - based search for module/function names

The re-forthcoming symbol-table-based probing would enable this.

>    *  probing  select/all functions in a given source file
>    *  probing inline functions.
>    *  statement probes

And of course these are impossible without debuginfo


- FChE


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