linux-kernel - Re: [PATCH 0/4] perf cs-etm: Track exception level

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Date:   Mon, 5 Jun 2023 16:44:45 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     James Clark <james.clark@....com>
Cc:     coresight@...ts.linaro.org, denik@...omium.org,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        John Garry <john.g.garry@...cle.com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] perf cs-etm: Track exception level

Em Wed, May 24, 2023 at 02:19:54PM +0100, James Clark escreveu:
> Some fixes to support an issue reported by Denis Nikitin where decoding
> trace that contains different EL1 and EL2 kernels can crash or go into
> an infinite loop because the wrong kernel maps are used for the decode.
> 
> This still doesn't support distinguishing guest and host userspace,
> we'd still have to fix the timestamps and do a bit more work to
> correlate that. And I've removed PERF_RECORD_MISC_HYPERVISOR as a
> possible outcome of cs_etm__cpu_mode(). As far as I know this could
> never have been returned anyway because machine__is_host(machine) was
> always true due to session.machines.host being hard coded. And I'm not
> sure of the relevance of the difference between PERF_RECORD_MISC_KERNEL
> and PERF_RECORD_MISC_HYPERVISOR in this scenario.
> 
> The first commit is a tidy up, second fixes a bug that I found when
> comparing the exception level and thread of branch records, the third
> is the main fix, and the last commit is some extra error checking. 
> 
> Applies to acme/perf-tools (4e111f0cf0)

So there seems to be agreement the first two patches can be applied? May
I go ahead and do that now?

- Arnaldo
 
> James Clark (4):
>   perf cs-etm: Only track threads instead of PID and TIDs
>   perf cs-etm: Use previous thread for branch sample source IP
>   perf cs-etm: Track exception level
>   perf cs-etm: Add exception level consistency check
> 
>  .../perf/util/cs-etm-decoder/cs-etm-decoder.c |  13 +-
>  .../perf/util/cs-etm-decoder/cs-etm-decoder.h |   4 +-
>  tools/perf/util/cs-etm.c                      | 220 +++++++++---------
>  tools/perf/util/cs-etm.h                      |   5 +-
>  4 files changed, 126 insertions(+), 116 deletions(-)
> 
> -- 
> 2.34.1
> 

-- 

- Arnaldo