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>
};
enum cs_etm_sample_type {
+ CS_ETM_EMPTY = 0,
CS_ETM_RANGE = 1 << 0,
CS_ETM_TRACE_ON = 1 << 1,
};
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
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.
*/
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;
}