Re: [PATCH v1 5/5] perf cs-etm: Track exception number

[Mathieu Poirier]

On Sun, Nov 11, 2018 at 12:59:43PM +0800, Leo Yan wrote:
> When an exception packet comes, it contains the info for exception
> number; the exception number indicates the exception types, so from it
> we can know if the exception is taken for interrupt, system call or
> other traps, etc.  But because the exception return packet cannot
> delivery exception number correctly by decoder thus when prepare sample
> flags we cannot know what's type for exception return.
> 
> This patch adds a new 'exc_num' array in decoder structure to record
> exception number per CPU, the exception number is recorded in the array
> when the exception packet comes and this exception number can be used by
> exception return packet.  If detect there have discontinuous trace with
> TRACE_ON or TRACE_OFF packet, the exception number is set to invalid
> value.
> 
> Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> ---
>  tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 67 ++++++++++++++++++++++---
>  1 file changed, 59 insertions(+), 8 deletions(-)
> 
> 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 b8cb7a3e..d1a6cbc 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> @@ -43,6 +43,7 @@ struct cs_etm_decoder {
>  	u32 packet_count;
>  	u32 head;
>  	u32 tail;
> +	u32 *exc_num;
>  	struct cs_etm_packet packet_buffer[MAX_BUFFER];
>  };
>  
> @@ -368,24 +369,64 @@ static ocsd_datapath_resp_t
>  cs_etm_decoder__buffer_trace_off(struct cs_etm_decoder *decoder,
>  				 const uint8_t trace_chan_id)
>  {
> -	return cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> -					     CS_ETM_TRACE_OFF);
> +	int ret;
> +	struct cs_etm_packet *packet;
> +
> +	ret = cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> +					    CS_ETM_TRACE_OFF);
> +	if (ret != OCSD_RESP_CONT && ret != OCSD_RESP_WAIT)
> +		return ret;
> +
> +	packet = &decoder->packet_buffer[decoder->tail];
> +
> +	/* Clear execption number for discontinuous trace */
> +	decoder->exc_num[packet->cpu] = UINT32_MAX;
> +
> +	return ret;
>  }
>  
>  static ocsd_datapath_resp_t
>  cs_etm_decoder__buffer_trace_on(struct cs_etm_decoder *decoder,
>  				const uint8_t trace_chan_id)
>  {
> -	return cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> -					     CS_ETM_TRACE_ON);
> +	int ret;
> +	struct cs_etm_packet *packet;
> +
> +	ret = cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> +					    CS_ETM_TRACE_ON);
> +	if (ret != OCSD_RESP_CONT && ret != OCSD_RESP_WAIT)
> +		return ret;
> +
> +	packet = &decoder->packet_buffer[decoder->tail];
> +
> +	/* Clear execption number for discontinuous trace */
> +	decoder->exc_num[packet->cpu] = UINT32_MAX;
> +
> +	return ret;
>  }
>  
>  static ocsd_datapath_resp_t
>  cs_etm_decoder__buffer_exception(struct cs_etm_decoder *decoder,
> +				 const ocsd_generic_trace_elem *elem,
>  				 const uint8_t trace_chan_id)
>  {
> -	return cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> -					     CS_ETM_EXCEPTION);
> +	int ret;
> +	struct cs_etm_packet *packet;
> +
> +	ret = cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> +					    CS_ETM_EXCEPTION);
> +	if (ret != OCSD_RESP_CONT && ret != OCSD_RESP_WAIT)
> +		return ret;
> +
> +	packet = &decoder->packet_buffer[decoder->tail];
> +
> +	/*
> +	 * Exception number is recorded per CPU and later can be used
> +	 * for exception return instruction analysis.
> +	 */
> +	decoder->exc_num[packet->cpu] = elem->exception_number;

Am I missing something or the information about the exception number that is
recorded here isn't used anywhere?  If you want to use this in perf report/script,
the exception number will have to be added to the cs_etm_packet struct.

I am done with the revision of this set.

Thanks,
Mathieu

> +
> +	return ret;
>  }
>  
>  static ocsd_datapath_resp_t
> @@ -423,7 +464,7 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
>  						    trace_chan_id);
>  		break;
>  	case OCSD_GEN_TRC_ELEM_EXCEPTION:
> -		resp = cs_etm_decoder__buffer_exception(decoder,
> +		resp = cs_etm_decoder__buffer_exception(decoder, elem,
>  							trace_chan_id);
>  		break;
>  	case OCSD_GEN_TRC_ELEM_EXCEPTION_RET:
> @@ -511,6 +552,10 @@ cs_etm_decoder__new(int num_cpu, struct cs_etm_decoder_params *d_params,
>  	if (!decoder)
>  		return NULL;
>  
> +	decoder->exc_num = zalloc(sizeof(*decoder->exc_num) * num_cpu);
> +	if (!decoder->exc_num)
> +		goto err_free_decoder;
> +
>  	decoder->data = d_params->data;
>  	decoder->prev_return = OCSD_RESP_CONT;
>  	cs_etm_decoder__clear_buffer(decoder);
> @@ -531,7 +576,7 @@ cs_etm_decoder__new(int num_cpu, struct cs_etm_decoder_params *d_params,
>  	decoder->dcd_tree = ocsd_create_dcd_tree(format, flags);
>  
>  	if (decoder->dcd_tree == 0)
> -		goto err_free_decoder;
> +		goto err_free_decoder_exc_num;
>  
>  	/* init library print logging support */
>  	ret = cs_etm_decoder__init_def_logger_printing(d_params, decoder);
> @@ -542,6 +587,9 @@ cs_etm_decoder__new(int num_cpu, struct cs_etm_decoder_params *d_params,
>  	cs_etm_decoder__init_raw_frame_logging(d_params, decoder);
>  
>  	for (i = 0; i < num_cpu; i++) {
> +		/* init expcetion number to an invalid value */
> +		decoder->exc_num[i] = UINT32_MAX;
> +
>  		ret = cs_etm_decoder__create_etm_decoder(d_params,
>  							 &t_params[i],
>  							 decoder);
> @@ -553,6 +601,8 @@ cs_etm_decoder__new(int num_cpu, struct cs_etm_decoder_params *d_params,
>  
>  err_free_decoder_tree:
>  	ocsd_destroy_dcd_tree(decoder->dcd_tree);
> +err_free_decoder_exc_num:
> +	free(decoder->exc_num);
>  err_free_decoder:
>  	free(decoder);
>  	return NULL;
> @@ -613,5 +663,6 @@ void cs_etm_decoder__free(struct cs_etm_decoder *decoder)
>  
>  	ocsd_destroy_dcd_tree(decoder->dcd_tree);
>  	decoder->dcd_tree = NULL;
> +	free(decoder->exc_num);
>  	free(decoder);
>  }
> -- 
> 2.7.4
>