Re: [PATCH 1/1] perf arm-spe: Inject SPE samples in perf-inject

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: German Gomez <german.gomez@arm.com>
Cc: James Clark <james.clark@arm.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Leo Yan <leo.yan@linaro.org>, Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] perf arm-spe: Inject SPE samples in perf-inject
Date: Wed, 17 Nov 2021 14:24:41 -0300	[thread overview]
Message-ID: <YZU62ekT9/NimdSq@kernel.org> (raw)
In-Reply-To: <aa79a8eb-e7fa-ad81-f4a3-a843b63020b2@arm.com>

Em Wed, Nov 17, 2021 at 04:27:27PM +0000, German Gomez escreveu:
> Hi Arnaldo,
> 
> On 17/11/2021 15:29, Arnaldo Carvalho de Melo wrote:
> > [...]
> > Next time please expand this explanations a bit more: why should we
> > inject such samples? Is this enabling some new mode of operation, fixing
> > something, what is an example of output before this patch and after it?
> I will keep this in mind, thanks. In this case the support was missing
> and I included the context in the cover letter but not the commit msg.

Got it, I'm adding it to the cset comment:

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perf-inject is currently not working for Arm SPE. When you try to run
perf-inject and perf-report with a perf.data file that contains SPE
traces, the tool reports a "Bad address" error:

  # ./perf record -e arm_spe_0/ts_enable=1,store_filter=1,branch_filter=1,load_filter=1/ -a -- sleep 1
  # ./perf inject -i perf.data -o perf.inject.data --itrace
  # ./perf report -i perf.inject.data --stdio

  0x42c00 [0x8]: failed to process type: 9 [Bad address]
  Error:
  failed to process sample

As far as I know, the issue was first spotted in [1], but perf-inject
was not yet injecting the samples. This patch does something similar to
what cs_etm does for injecting the samples [2], but for SPE.

[1] https://patchwork.kernel.org/project/linux-arm-kernel/cover/20210412091006.468557-1-leo.yan@linaro.org/#24117339
[2] https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/perf/util/cs-etm.c?h=perf/core&id=133fe2e617e48ca0948983329f43877064ffda3e#n1196
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