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Date:   Tue, 19 Mar 2019 15:13:16 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     kan.liang@linux.intel.com
Cc:     acme@kernel.org, mingo@redhat.com, linux-kernel@vger.kernel.org,
        tglx@linutronix.de, jolsa@kernel.org, eranian@google.com,
        alexander.shishkin@linux.intel.com, ak@linux.intel.com
Subject: Re: [PATCH 01/22] perf/core: Support outputting registers from a
 separate array
Message-ID: <20190319141316.GH6521@hirez.programming.kicks-ass.net>
References: <20190318214144.4639-1-kan.liang@linux.intel.com>
 <20190318214144.4639-2-kan.liang@linux.intel.com>
 <20190319130004.GF5996@hirez.programming.kicks-ass.net>
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On Tue, Mar 19, 2019 at 02:00:04PM +0100, Peter Zijlstra wrote:
> On Mon, Mar 18, 2019 at 02:41:23PM -0700, kan.liang@linux.intel.com wrote:

> > @@ -6274,6 +6275,7 @@ void perf_output_sample(struct perf_output_handle *handle,
> >  			u64 mask = event->attr.sample_regs_user;
> >  			perf_output_sample_regs(handle,
> >  						data->regs_user.regs,
> > +						NULL,
> >  						mask);
> >  		}
> >  	}
> > @@ -6306,6 +6308,7 @@ void perf_output_sample(struct perf_output_handle *handle,
> >  
> >  			perf_output_sample_regs(handle,
> >  						data->regs_intr.regs,
> > +						data->extra_regs,
> >  						mask);
> >  		}
> >  	}
> 
> See, I think most of this is completely unnessecary. Both sites pass:
> &perf_regs::regs to perf_output_sample_regs()<-perf_reg_value().
> 
> So all you need to do is add the XMM crud to perf_regs, and use
> container_of() on the pt_regs pointer in perf_reg_value() to get back to
> perf_regs and voila, XMM registers.

Ah, that's not quite true, but I still think you can make something like
that work.