linux-kernel - Re: [PATCH v6 1/8] perf cs-etm: Add last instruction information in packet

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Message-ID: <20190123210307.GA620@xps15>
Date:   Wed, 23 Jan 2019 14:03:07 -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>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Mike Leach <mike.leach@...aro.org>,
        Robert Walker <robert.walker@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Coresight ML <coresight@...ts.linaro.org>
Subject: Re: [PATCH v6 1/8] perf cs-etm: Add last instruction information in
 packet

On Sat, Jan 19, 2019 at 09:43:40AM +0800, Leo Yan wrote:
> Decoder provides last instruction related information, these information
> can be used for trace analysis; specifically we can get to know what
> kind of branch instruction has been executed, mainly the information
> are contained in three element fields:
> 
>   last_i_type: this is significant type for waypoint calculation, it
>   indicates the last instruction is one of immediate branch instruction,
>   indirect branch instruction, instruction barrier (ISB), or data
>   barrier (DSB/DMB).
> 
>   last_i_subtype: this is used for instruction sub type, it can be
>   branch with link, ARMv8 return instruction, ARMv8 eret instruction
>   (return from exception), or ARMv7 instruction which could imply
>   return (e.g. MOV PC, LR; POP { ,PC}).
> 
>   last_instr_cond: it indicates if the last instruction was conditional.
> 
> But these three fields are not saved into cs_etm_packet struct, thus
> cs-etm layer don't know related information and cannot generate sample
> flags for branch instructions.
> 
> This patch add corresponding three new fields in cs_etm_packet struct
> and save related value into the packet structure, it is preparation for
> supporting sample flags.
> 
> Signed-off-by: Leo Yan <leo.yan@...aro.org>
> ---
>  tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 9 +++++++++
>  tools/perf/util/cs-etm-decoder/cs-etm-decoder.h | 3 +++
>  2 files changed, 12 insertions(+)
> 
> 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 8c155575c6c5..8a19310500d9 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> @@ -290,6 +290,9 @@ static void cs_etm_decoder__clear_buffer(struct cs_etm_decoder *decoder)
>  		decoder->packet_buffer[i].instr_count = 0;
>  		decoder->packet_buffer[i].last_instr_taken_branch = false;
>  		decoder->packet_buffer[i].last_instr_size = 0;
> +		decoder->packet_buffer[i].last_instr_type = 0;
> +		decoder->packet_buffer[i].last_instr_subtype = 0;
> +		decoder->packet_buffer[i].last_instr_cond = 0;
>  		decoder->packet_buffer[i].cpu = INT_MIN;
>  	}
>  }
> @@ -323,6 +326,9 @@ cs_etm_decoder__buffer_packet(struct cs_etm_decoder *decoder,
>  	decoder->packet_buffer[et].instr_count = 0;
>  	decoder->packet_buffer[et].last_instr_taken_branch = false;
>  	decoder->packet_buffer[et].last_instr_size = 0;
> +	decoder->packet_buffer[et].last_instr_type = 0;
> +	decoder->packet_buffer[et].last_instr_subtype = 0;
> +	decoder->packet_buffer[et].last_instr_cond = 0;
>  
>  	if (decoder->packet_count == MAX_BUFFER - 1)
>  		return OCSD_RESP_WAIT;
> @@ -366,6 +372,9 @@ cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder,
>  	packet->start_addr = elem->st_addr;
>  	packet->end_addr = elem->en_addr;
>  	packet->instr_count = elem->num_instr_range;
> +	packet->last_instr_type = elem->last_i_type;
> +	packet->last_instr_subtype = elem->last_i_subtype;
> +	packet->last_instr_cond = elem->last_instr_cond;
>  
>  	switch (elem->last_i_type) {
>  	case OCSD_INSTR_BR:
> diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> index a6407d41598f..7cdd6a9c68a7 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> @@ -43,6 +43,9 @@ struct cs_etm_packet {
>  	u64 start_addr;
>  	u64 end_addr;
>  	u32 instr_count;
> +	u32 last_instr_type;
> +	u32 last_instr_subtype;
> +	u8 last_instr_cond;
>  	u8 last_instr_taken_branch;
>  	u8 last_instr_size;
>  	int cpu;

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

> -- 
> 2.17.1
>