linux-kernel - Re: [PATCH 2/2] perf annotate: add powerpc support

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Message-Id: <20160610143822.GT18654@naverao1-tp.localdomain>
Date:	Fri, 10 Jun 2016 20:08:22 +0530
From:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	Anton Blanchard <anton@...abs.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	He Kuang <hekuang@...wei.com>
Subject: Re: [PATCH 2/2] perf annotate: add powerpc support

On 2016/06/10 10:36AM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Jun 10, 2016 at 06:32:51PM +0530, Naveen N. Rao escreveu:
> > Convert ins__find() to a __weak function for generic functionality,
> > while adding a powerpc-specific variant. We look at the function name
> > for branch instructions and classify the instructions to one among a
> > branch, a function call (branch with LR update) or a function return
> > (branch to LR).
> 
> How would this allow one to get a perf.data collected on a powerpc
> system, transfer it to a x86-64 (or aarch64, to mention another
> workstation wannabe chip) system and then try annotating it?
> 
> There was a previous discussion about this, and it involved having all
> yout ppc tables available as well as other arches tables, and then
> choosing which one to use based on:
> 
> 	normalize_arch(thread->mg->machine->env->arch)
> 
> just like was done for support cross unwinding, see recent patch kit by
> He Kuang, CCed.

Nice. This would be good to have. I will look at adding powerpc support 
for cross-architecture unwind.

However, for cross-architecture annotation, I think there will be a lot 
more dependencies since perf currently uses objdump to obtain the 
disassembly. In addition, the actual binaries will also be needed.


- Naveen