linux-kernel - Re: [PATCH v3 6/8] perf cs-etm: Add helper cs_etm__get_pid

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Date:   Mon, 8 Feb 2021 13:32:10 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Daniel Kiss <Daniel.Kiss@....com>,
        Denis Nikitin <denik@...omium.org>,
        Al Grant <al.grant@....com>, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 6/8] perf cs-etm: Add helper cs_etm__get_pid_fmt()

On Sat, Feb 06, 2021 at 11:08:31PM +0800, Leo Yan wrote:
> This patch adds helper function cs_etm__get_pid_fmt(), by passing
> parameter "traceID", it returns the PID format.
> 
> Signed-off-by: Leo Yan <leo.yan@...aro.org>

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

> ---
>  tools/perf/util/cs-etm.c | 42 ++++++++++++++++++++++++++++++++++++++++
>  tools/perf/util/cs-etm.h |  1 +
>  2 files changed, 43 insertions(+)
> 
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index a2a369e2fbb6..b9c1d329a7f1 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -7,6 +7,7 @@
>   */
>  
>  #include <linux/bitops.h>
> +#include <linux/coresight-pmu.h>
>  #include <linux/err.h>
>  #include <linux/kernel.h>
>  #include <linux/log2.h>
> @@ -156,6 +157,47 @@ int cs_etm__get_cpu(u8 trace_chan_id, int *cpu)
>  	return 0;
>  }
>  
> +/*
> + * The returned PID format is presented by two bits:
> + *
> + *   Bit ETM_OPT_CTXTID: CONTEXTIDR or CONTEXTIDR_EL1 is traced;
> + *   Bit ETM_OPT_CTXTID2: CONTEXTIDR_EL2 is traced.
> + *
> + * It's possible that the two bits ETM_OPT_CTXTID and ETM_OPT_CTXTID2
> + * are enabled at the same time when the session runs on an EL2 kernel.
> + * This means the CONTEXTIDR_EL1 and CONTEXTIDR_EL2 both will be
> + * recorded in the trace data, the tool will selectively use
> + * CONTEXTIDR_EL2 as PID.
> + */
> +int cs_etm__get_pid_fmt(u8 trace_chan_id, u64 *pid_fmt)
> +{
> +	struct int_node *inode;
> +	u64 *metadata, val;
> +
> +	inode = intlist__find(traceid_list, trace_chan_id);
> +	if (!inode)
> +		return -EINVAL;
> +
> +	metadata = inode->priv;
> +
> +	if (metadata[CS_ETM_MAGIC] == __perf_cs_etmv3_magic) {
> +		val = metadata[CS_ETM_ETMCR];
> +		/* CONTEXTIDR is traced */
> +		if (val & BIT(ETM_OPT_CTXTID))
> +			*pid_fmt = BIT(ETM_OPT_CTXTID);
> +	} else {
> +		val = metadata[CS_ETMV4_TRCCONFIGR];
> +		/* CONTEXTIDR_EL2 is traced */
> +		if (val & (BIT(ETM4_CFG_BIT_VMID) | BIT(ETM4_CFG_BIT_VMID_OPT)))
> +			*pid_fmt = BIT(ETM_OPT_CTXTID2);
> +		/* CONTEXTIDR_EL1 is traced */
> +		else if (val & BIT(ETM4_CFG_BIT_CTXTID))
> +			*pid_fmt = BIT(ETM_OPT_CTXTID);
> +	}
> +
> +	return 0;
> +}
> +
>  void cs_etm__etmq_set_traceid_queue_timestamp(struct cs_etm_queue *etmq,
>  					      u8 trace_chan_id)
>  {
> diff --git a/tools/perf/util/cs-etm.h b/tools/perf/util/cs-etm.h
> index 4ad925d6d799..7cc3bba0017d 100644
> --- a/tools/perf/util/cs-etm.h
> +++ b/tools/perf/util/cs-etm.h
> @@ -173,6 +173,7 @@ struct cs_etm_packet_queue {
>  int cs_etm__process_auxtrace_info(union perf_event *event,
>  				  struct perf_session *session);
>  int cs_etm__get_cpu(u8 trace_chan_id, int *cpu);
> +int cs_etm__get_pid_fmt(u8 trace_chan_id, u64 *pid_fmt);
>  int cs_etm__etmq_set_tid(struct cs_etm_queue *etmq,
>  			 pid_t tid, u8 trace_chan_id);
>  bool cs_etm__etmq_is_timeless(struct cs_etm_queue *etmq);
> -- 
> 2.25.1
>