linux-kernel - Re: [PATCH v3 0/5] perf cs-etm: Track exception level

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Message-ID: <94e91db2-182e-836f-2edc-f804c4bb7290@arm.com>
Date:   Tue, 13 Jun 2023 09:56:29 +0100
From:   James Clark <james.clark@....com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     coresight@...ts.linaro.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 v3 0/5] perf cs-etm: Track exception level



On 12/06/2023 19:32, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jun 12, 2023 at 12:13:57PM +0100, James Clark escreveu:
>> Changes since v2:
>>
>>   * Rename prev_thread -> prev_packet_thread and prev_el ->
>>     prev_packet_el
>>   * Add a comment about tracking the previous packet's thread
>>
>> Changes since v1:
>>
>>   * Always assume host kernel when the trace was captured at EL1 (nVHE)
>>   * Fix EL validation to work with ETMv3
>>   * Add a commit to make PID format accessible from struct
>>     cs_etm_auxtrace
> 
> Please take a look in my tmp.perf-tools-next branch, there were some
> conflicts I had to fix as those files were touched by refactorings for
> addr_location and thread reference counting.
> 

Yeah I got the same result and the tests are still passing. Thanks for
fixing those.

> ⬢[acme@...lbox perf-tools-next]$ git log --oneline -10
> aa53fb2c482e70c2 (HEAD -> perf-tools-next) perf cs-etm: Add exception level consistency check
> 2918e9895224541f perf cs-etm: Track exception level
> f492a33909829a75 perf cs-etm: Make PID format accessible from struct cs_etm_auxtrace
> e29ec19b0751c6b2 perf cs-etm: Use previous thread for branch sample source IP
> e9e03e9c3ca7088c perf cs-etm: Only track threads instead of PID and TIDs
> 6fd34445b8c94aa7 perf map: Fix double 'struct map' reference free found with -DREFCNT_CHECKING=1
> e9c0a7f63e45e76f perf srcline: Optimize comparision against SRCLINE_UNKNOWN
> fd87a79c7ed62804 perf hist: Fix srcline memory leak
> 933f9651d47cdda2 perf srcline: Change free_srcline to zfree_srcline
> d22cfb063bcc674e perf callchain: Use pthread keys for tls callchain_cursor
> ⬢[acme@...lbox perf-tools-next]$
> 
> 
> - Arnaldo
>  
>> ======
>>
>> 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-next (42713dafc)
>>
>> James Clark (5):
>>   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: Make PID format accessible from struct cs_etm_auxtrace
>>   perf cs-etm: Track exception level
>>   perf cs-etm: Add exception level consistency check
>>
>>  .../perf/util/cs-etm-decoder/cs-etm-decoder.c |  33 +-
>>  .../perf/util/cs-etm-decoder/cs-etm-decoder.h |   4 +-
>>  tools/perf/util/cs-etm.c                      | 282 ++++++++++--------
>>  tools/perf/util/cs-etm.h                      |  13 +-
>>  4 files changed, 184 insertions(+), 148 deletions(-)
>>
>> -- 
>> 2.34.1
>>
>