linux-kernel - Re: [PATCH 2/6] perf cs-etm: Initialise architecture based on TRCIDR1

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Date:   Thu, 22 Jul 2021 12:10:35 +0100
From:   Mike Leach <mike.leach@...aro.org>
To:     James Clark <james.clark@....com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Coresight ML <coresight@...ts.linaro.org>,
        Leo Yan <leo.yan@...aro.org>, Al Grant <al.grant@....com>,
        "Suzuki K. Poulose" <suzuki.poulose@....com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 2/6] perf cs-etm: Initialise architecture based on TRCIDR1

HI James

On Wed, 21 Jul 2021 at 10:07, James Clark <james.clark@....com> wrote:
>
> Currently the architecture is hard coded as ARCH_V8, but with the
> introduction of ETE we want to pick ARCH_AA64. And this change is also
> applicable to ETM v4.4 onwards as well.
>
> Signed-off-by: James Clark <james.clark@....com>
> ---
>  tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> index 30889a9d0165..5972a8afcc6b 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> @@ -126,6 +126,18 @@ static int cs_etm_decoder__gen_etmv3_config(struct cs_etm_trace_params *params,
>         return 0;
>  }
>
> +#define TRCIDR1_TRCARCHMIN_SHIFT 4
> +#define TRCIDR1_TRCARCHMIN_MASK  GENMASK(7, 4)
> +#define TRCIDR1_TRCARCHMIN(x)    (((x) & TRCIDR1_TRCARCHMIN_MASK) >> TRCIDR1_TRCARCHMIN_SHIFT)
> +static enum _ocsd_arch_version cs_etm_decoder__get_arch_ver(u32 reg_idr1)
> +{
> +       /*
> +        * If the ETM trace minor version is 4 or more then we can assume
> +        * the architecture is ARCH_AA64 rather than just V8
> +        */
> +       return TRCIDR1_TRCARCHMIN(reg_idr1) >= 4 ? ARCH_AA64 : ARCH_V8;
> +}

This is true for ETM4.x & ETE 1.x (arch 5.x) but not ETM 3.x
Probably need to beef up this comment or the function name to emphasise this.

Also only true because we don't currently support AArch32 builds of
the ETM4.x driver.

Regards

Mike

> +
>  static void cs_etm_decoder__gen_etmv4_config(struct cs_etm_trace_params *params,
>                                              ocsd_etmv4_cfg *config)
>  {
> @@ -140,7 +152,7 @@ static void cs_etm_decoder__gen_etmv4_config(struct cs_etm_trace_params *params,
>         config->reg_idr11 = 0;
>         config->reg_idr12 = 0;
>         config->reg_idr13 = 0;
> -       config->arch_ver = ARCH_V8;
> +       config->arch_ver = cs_etm_decoder__get_arch_ver(params->etmv4.reg_idr1);
>         config->core_prof = profile_CortexA;
>  }
>
> --
> 2.28.0
>


-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK