Commit 3eb3e07b authored Jul 11, 2018 by Leo Yan Committed by Arnaldo Carvalho de Melo Jul 31, 2018

perf cs-etm: Fix start tracing packet handling



Usually the start tracing packet is a CS_ETM_TRACE_ON packet, this
packet is passed to cs_etm__flush();  cs_etm__flush() will check the
condition 'prev_packet->sample_type == CS_ETM_RANGE' but 'prev_packet'
is allocated by zalloc() so 'prev_packet->sample_type' is zero in
initialization and this condition is false.  So cs_etm__flush() will
directly bail out without handling the start tracing packet.

This patch is to introduce a new sample type CS_ETM_EMPTY, which is used
to indicate the packet is an empty packet.  cs_etm__flush() will swap
packets when it finds the previous packet is empty, so this can record
the start tracing packet into 'etmq->prev_packet'.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Walker <robert.walker@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1531295145-596-4-git-send-email-leo.yan@linaro.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 83868bf7

tools/perf/util/cs-etm-decoder/cs-etm-decoder.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -23,6 +23,7 @@ struct cs_etm_buffer {
		};

		enum cs_etm_sample_type {
		CS_ETM_EMPTY = 0,
		CS_ETM_RANGE = 1 << 0,
		CS_ETM_TRACE_ON = 1 << 1,
		};

tools/perf/util/cs-etm.c

+18 −1

Original line number	Diff line number	Diff line
		@@ -924,8 +924,14 @@ static int cs_etm__flush(struct cs_etm_queue *etmq)
		int err = 0;
		struct cs_etm_packet *tmp;

		if (!etmq->prev_packet)
		return 0;

		/* Handle start tracing packet */
		if (etmq->prev_packet->sample_type == CS_ETM_EMPTY)
		goto swap_packet;

		if (etmq->etm->synth_opts.last_branch &&
		etmq->prev_packet &&
		etmq->prev_packet->sample_type == CS_ETM_RANGE) {
		/*
		* Generate a last branch event for the branches left in the
		@@ -944,6 +950,10 @@ static int cs_etm__flush(struct cs_etm_queue *etmq)

		etmq->period_instructions = 0;

		}

		swap_packet:
		if (etmq->etm->synth_opts.last_branch) {
		/*
		* Swap PACKET with PREV_PACKET: PACKET becomes PREV_PACKET for
		* the next incoming packet.
		@@ -1023,6 +1033,13 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
		*/
		cs_etm__flush(etmq);
		break;
		case CS_ETM_EMPTY:
		/*
		* Should not receive empty packet,
		* report error.
		*/
		pr_err("CS ETM Trace: empty packet\n");
		return -EINVAL;
		default:
		break;
		}