linux-kernel - Re: [PATCH 1/2] perf cs-etm: Support sample flags 'insn' and 'insnlen'

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Date:   Mon, 19 Aug 2019 11:23:21 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Leo Yan <leo.yan@...aro.org>
Cc:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Mike Leach <mike.leach@...aro.org>,
        Robert Walker <robert.walker@....com>,
        coresight@...ts.linaro.org
Subject: Re: [PATCH 1/2] perf cs-etm: Support sample flags 'insn' and
 'insnlen'

Em Thu, Aug 15, 2019 at 04:28:54PM +0800, Leo Yan escreveu:
> The synthetic branch and instruction samples are missed to set
> instruction related info, thus perf tool fails to display samples with
> flags '-F,+insn,+insnlen'.
> 
> CoreSight trace decoder has provided sufficient information to decide
> the instruction size based on the isa type: A64/A32 instruction are
> 32-bit size, but one exception is the T32 instruction size, which might
> be 32-bit or 16-bit.
> 
> This patch handles for these cases and it reads the instruction values
> from DSO file; thus can support flags '-F,+insn,+insnlen'.

Mathieu, can I have your Acked-by/Reviewed-by?

- Arnaldo
 
> Before:
> 
>   # perf script -F,insn,insnlen,ip,sym
>                 0 [unknown] ilen: 0
>      ffff97174044 _start ilen: 0
>      ffff97174938 _dl_start ilen: 0
>      ffff97174938 _dl_start ilen: 0
>      ffff97174938 _dl_start ilen: 0
>      ffff97174938 _dl_start ilen: 0
>      ffff97174938 _dl_start ilen: 0
>      ffff97174938 _dl_start ilen: 0
>      ffff97174938 _dl_start ilen: 0
>      ffff97174938 _dl_start ilen: 0
> 
>   [...]
> 
> After:
> 
>   # perf script -F,insn,insnlen,ip,sym
>                 0 [unknown] ilen: 0
>      ffff97174044 _start ilen: 4 insn: 2f 02 00 94
>      ffff97174938 _dl_start ilen: 4 insn: c1 ff ff 54
>      ffff97174938 _dl_start ilen: 4 insn: c1 ff ff 54
>      ffff97174938 _dl_start ilen: 4 insn: c1 ff ff 54
>      ffff97174938 _dl_start ilen: 4 insn: c1 ff ff 54
>      ffff97174938 _dl_start ilen: 4 insn: c1 ff ff 54
>      ffff97174938 _dl_start ilen: 4 insn: c1 ff ff 54
>      ffff97174938 _dl_start ilen: 4 insn: c1 ff ff 54
>      ffff97174938 _dl_start ilen: 4 insn: c1 ff ff 54
> 
>   [...]
> 
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Cc: Suzuki Poulouse <suzuki.poulose@....com>
> Cc: Mike Leach <mike.leach@...aro.org>
> Cc: Robert Walker <robert.walker@....com>
> Cc: coresight@...ts.linaro.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Signed-off-by: Leo Yan <leo.yan@...aro.org>
> ---
>  tools/perf/util/cs-etm.c | 35 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index ed6f7fd5b90b..b3a5daaf1a8f 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -1076,6 +1076,35 @@ bool cs_etm__etmq_is_timeless(struct cs_etm_queue *etmq)
>  	return !!etmq->etm->timeless_decoding;
>  }
>  
> +static void cs_etm__copy_insn(struct cs_etm_queue *etmq,
> +			      u64 trace_chan_id,
> +			      const struct cs_etm_packet *packet,
> +			      struct perf_sample *sample)
> +{
> +	/*
> +	 * It's pointless to read instructions for the CS_ETM_DISCONTINUITY
> +	 * packet, so directly bail out with 'insn_len' = 0.
> +	 */
> +	if (packet->sample_type == CS_ETM_DISCONTINUITY) {
> +		sample->insn_len = 0;
> +		return;
> +	}
> +
> +	/*
> +	 * T32 instruction size might be 32-bit or 16-bit, decide by calling
> +	 * cs_etm__t32_instr_size().
> +	 */
> +	if (packet->isa == CS_ETM_ISA_T32)
> +		sample->insn_len = cs_etm__t32_instr_size(etmq, trace_chan_id,
> +							  sample->ip);
> +	/* Otherwise, A64 and A32 instruction size are always 32-bit. */
> +	else
> +		sample->insn_len = 4;
> +
> +	cs_etm__mem_access(etmq, trace_chan_id, sample->ip,
> +			   sample->insn_len, (void *)sample->insn);
> +}
> +
>  static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
>  					    struct cs_etm_traceid_queue *tidq,
>  					    u64 addr, u64 period)
> @@ -1097,9 +1126,10 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
>  	sample.period = period;
>  	sample.cpu = tidq->packet->cpu;
>  	sample.flags = tidq->prev_packet->flags;
> -	sample.insn_len = 1;
>  	sample.cpumode = event->sample.header.misc;
>  
> +	cs_etm__copy_insn(etmq, tidq->trace_chan_id, tidq->packet, &sample);
> +
>  	if (etm->synth_opts.last_branch) {
>  		cs_etm__copy_last_branch_rb(etmq, tidq);
>  		sample.branch_stack = tidq->last_branch;
> @@ -1159,6 +1189,9 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
>  	sample.flags = tidq->prev_packet->flags;
>  	sample.cpumode = event->sample.header.misc;
>  
> +	cs_etm__copy_insn(etmq, tidq->trace_chan_id, tidq->prev_packet,
> +			  &sample);
> +
>  	/*
>  	 * perf report cannot handle events without a branch stack
>  	 */
> -- 
> 2.17.1

-- 

- Arnaldo