Subject: Re: [PATCH v6 2/8] perf cs-etm: Set sample flags for instruction range packet

From: Mathieu Poirier <[email-masked]>
Date: Wed, 23 Jan 2019 14:03:48 -0700

On Sat, Jan 19, 2019 at 09:43:41AM +0800, Leo Yan wrote:
> The perf sample data contains flags to indicate the hardware trace data
> is belonging to which type branch instruction, thus this can be used to
> print out the human readable string.  Arm CoreSight ETM sample data is
> missed to set flags and it is always set to zeros, this results in perf
> tool skips to print string for instruction types.
> 
> This patch is to set branch instruction flags for instruction range
> packet.
> 
> Signed-off-by: Leo Yan <[email-masked]>
> ---
>  .../perf/util/cs-etm-decoder/cs-etm-decoder.c |  2 +
>  .../perf/util/cs-etm-decoder/cs-etm-decoder.h |  1 +
>  tools/perf/util/cs-etm.c                      | 90 ++++++++++++++++++-
>  3 files changed, 91 insertions(+), 2 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 8a19310500d9..e98ee49a1527 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> @@ -293,6 +293,7 @@ static void cs_etm_decoder__clear_buffer(struct cs_etm_decoder *decoder)
>  		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].flags = 0;
>  		decoder->packet_buffer[i].cpu = INT_MIN;
>  	}
>  }
> @@ -329,6 +330,7 @@ cs_etm_decoder__buffer_packet(struct cs_etm_decoder *decoder,
>  	decoder->packet_buffer[et].last_instr_type = 0;
>  	decoder->packet_buffer[et].last_instr_subtype = 0;
>  	decoder->packet_buffer[et].last_instr_cond = 0;
> +	decoder->packet_buffer[et].flags = 0;
>  
>  	if (decoder->packet_count == MAX_BUFFER - 1)
>  		return OCSD_RESP_WAIT;
> 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 7cdd6a9c68a7..23600e57a215 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> @@ -45,6 +45,7 @@ struct cs_etm_packet {
>  	u32 instr_count;
>  	u32 last_instr_type;
>  	u32 last_instr_subtype;
> +	u32 flags;
>  	u8 last_instr_cond;
>  	u8 last_instr_taken_branch;
>  	u8 last_instr_size;
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index 27a374ddf661..d05cac5295f1 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -12,6 +12,7 @@
>  #include <linux/log2.h>
>  #include <linux/types.h>
>  
> +#include <opencsd/ocsd_if_types.h>
>  #include <stdlib.h>
>  
>  #include "auxtrace.h"
> @@ -719,7 +720,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
>  	sample.stream_id = etmq->etm->instructions_id;
>  	sample.period = period;
>  	sample.cpu = etmq->packet->cpu;
> -	sample.flags = 0;
> +	sample.flags = etmq->prev_packet->flags;
>  	sample.insn_len = 1;
>  	sample.cpumode = event->sample.header.misc;
>  
> @@ -778,7 +779,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq)
>  	sample.stream_id = etmq->etm->branches_id;
>  	sample.period = 1;
>  	sample.cpu = etmq->packet->cpu;
> -	sample.flags = 0;
> +	sample.flags = etmq->prev_packet->flags;
>  	sample.cpumode = event->sample.header.misc;
>  
>  	/*
> @@ -1107,6 +1108,80 @@ static int cs_etm__end_block(struct cs_etm_queue *etmq)
>  	return 0;
>  }
>  
> +static int cs_etm__set_sample_flags(struct cs_etm_queue *etmq)
> +{
> +	struct cs_etm_packet *packet = etmq->packet;
> +
> +	switch (packet->sample_type) {
> +	case CS_ETM_RANGE:
> +		/*
> +		 * Immediate branch instruction without neither link nor
> +		 * return flag, it's normal branch instruction within
> +		 * the function.
> +		 */
> +		if (packet->last_instr_type == OCSD_INSTR_BR &&
> +		    packet->last_instr_subtype == OCSD_S_INSTR_NONE) {
> +			packet->flags = PERF_IP_FLAG_BRANCH;
> +
> +			if (packet->last_instr_cond)
> +				packet->flags |= PERF_IP_FLAG_CONDITIONAL;
> +		}
> +
> +		/*
> +		 * Immediate branch instruction with link (e.g. BL), this is
> +		 * branch instruction for function call.
> +		 */
> +		if (packet->last_instr_type == OCSD_INSTR_BR &&
> +		    packet->last_instr_subtype == OCSD_S_INSTR_BR_LINK)
> +			packet->flags = PERF_IP_FLAG_BRANCH |
> +					PERF_IP_FLAG_CALL;
> +
> +		/*
> +		 * Indirect branch instruction with link (e.g. BLR), this is
> +		 * branch instruction for function call.
> +		 */
> +		if (packet->last_instr_type == OCSD_INSTR_BR_INDIRECT &&
> +		    packet->last_instr_subtype == OCSD_S_INSTR_BR_LINK)
> +			packet->flags = PERF_IP_FLAG_BRANCH |
> +					PERF_IP_FLAG_CALL;
> +
> +		/*
> +		 * Indirect branch instruction with subtype of
> +		 * OCSD_S_INSTR_V7_IMPLIED_RET, this is explicit hint for
> +		 * function return for A32/T32.
> +		 */
> +		if (packet->last_instr_type == OCSD_INSTR_BR_INDIRECT &&
> +		    packet->last_instr_subtype == OCSD_S_INSTR_V7_IMPLIED_RET)
> +			packet->flags = PERF_IP_FLAG_BRANCH |
> +					PERF_IP_FLAG_RETURN;
> +
> +		/*
> +		 * Indirect branch instruction without link (e.g. BR), usually
> +		 * this is used for function return, especially for functions
> +		 * within dynamic link lib.
> +		 */
> +		if (packet->last_instr_type == OCSD_INSTR_BR_INDIRECT &&
> +		    packet->last_instr_subtype == OCSD_S_INSTR_NONE)
> +			packet->flags = PERF_IP_FLAG_BRANCH |
> +					PERF_IP_FLAG_RETURN;
> +
> +		/* Return instruction for function return. */
> +		if (packet->last_instr_type == OCSD_INSTR_BR_INDIRECT &&
> +		    packet->last_instr_subtype == OCSD_S_INSTR_V8_RET)
> +			packet->flags = PERF_IP_FLAG_BRANCH |
> +					PERF_IP_FLAG_RETURN;
> +		break;
> +	case CS_ETM_DISCONTINUITY:
> +	case CS_ETM_EXCEPTION:
> +	case CS_ETM_EXCEPTION_RET:
> +	case CS_ETM_EMPTY:
> +	default:
> +		break;
> +	}
> +
> +	return 0;
> +}
> +
>  static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
>  {
>  	struct cs_etm_auxtrace *etm = etmq->etm;
> @@ -1158,6 +1233,17 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
>  					 */
>  					break;
>  
> +				/*
> +				 * Since packet addresses are swapped in packet
> +				 * handling within below switch() statements,
> +				 * thus setting sample flags must be called
> +				 * prior to switch() statement to use address
> +				 * information before packets swapping.
> +				 */
> +				err = cs_etm__set_sample_flags(etmq);
> +				if (err < 0)
> +					break;
> +
>  				switch (etmq->packet->sample_type) {
>  				case CS_ETM_RANGE:
>  					/*

Reviewed-by: Mathieu Poirier <[email-masked]>

> -- 
> 2.17.1

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