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Subject[PATCH 53/85] perf cs-etm: Add support for CPU-wide trace scenarios
Date
From: Mathieu Poirier <mathieu.poirier@linaro.org>

Add support for CPU-wide trace scenarios by correlating range packets
with timestamp packets. That way range packets received on different
ETMQ/traceID channels can be processed and synthesized in chronological
order.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190524173508.29044-18-mathieu.poirier@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/cs-etm.c | 254 +++++++++++++++++++++++++++++++++++++--
1 file changed, 246 insertions(+), 8 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 91496a3a2209..0c7776b51045 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -90,12 +90,26 @@ struct cs_etm_queue {
};

static int cs_etm__update_queues(struct cs_etm_auxtrace *etm);
+static int cs_etm__process_queues(struct cs_etm_auxtrace *etm);
static int cs_etm__process_timeless_queues(struct cs_etm_auxtrace *etm,
pid_t tid);
+static int cs_etm__get_data_block(struct cs_etm_queue *etmq);
+static int cs_etm__decode_data_block(struct cs_etm_queue *etmq);

/* PTMs ETMIDR [11:8] set to b0011 */
#define ETMIDR_PTM_VERSION 0x00000300

+/*
+ * A struct auxtrace_heap_item only has a queue_nr and a timestamp to
+ * work with. One option is to modify to auxtrace_heap_XYZ() API or simply
+ * encode the etm queue number as the upper 16 bit and the channel as
+ * the lower 16 bit.
+ */
+#define TO_CS_QUEUE_NR(queue_nr, trace_id_chan) \
+ (queue_nr << 16 | trace_chan_id)
+#define TO_QUEUE_NR(cs_queue_nr) (cs_queue_nr >> 16)
+#define TO_TRACE_CHAN_ID(cs_queue_nr) (cs_queue_nr & 0x0000ffff)
+
static u32 cs_etm__get_v7_protocol_version(u32 etmidr)
{
etmidr &= ETMIDR_PTM_VERSION;
@@ -147,6 +161,29 @@ void cs_etm__etmq_set_traceid_queue_timestamp(struct cs_etm_queue *etmq,
etmq->pending_timestamp = trace_chan_id;
}

+static u64 cs_etm__etmq_get_timestamp(struct cs_etm_queue *etmq,
+ u8 *trace_chan_id)
+{
+ struct cs_etm_packet_queue *packet_queue;
+
+ if (!etmq->pending_timestamp)
+ return 0;
+
+ if (trace_chan_id)
+ *trace_chan_id = etmq->pending_timestamp;
+
+ packet_queue = cs_etm__etmq_get_packet_queue(etmq,
+ etmq->pending_timestamp);
+ if (!packet_queue)
+ return 0;
+
+ /* Acknowledge pending status */
+ etmq->pending_timestamp = 0;
+
+ /* See function cs_etm_decoder__do_{hard|soft}_timestamp() */
+ return packet_queue->timestamp;
+}
+
static void cs_etm__clear_packet_queue(struct cs_etm_packet_queue *queue)
{
int i;
@@ -171,6 +208,20 @@ static void cs_etm__clear_packet_queue(struct cs_etm_packet_queue *queue)
}
}

+static void cs_etm__clear_all_packet_queues(struct cs_etm_queue *etmq)
+{
+ int idx;
+ struct int_node *inode;
+ struct cs_etm_traceid_queue *tidq;
+ struct intlist *traceid_queues_list = etmq->traceid_queues_list;
+
+ intlist__for_each_entry(inode, traceid_queues_list) {
+ idx = (int)(intptr_t)inode->priv;
+ tidq = etmq->traceid_queues[idx];
+ cs_etm__clear_packet_queue(&tidq->packet_queue);
+ }
+}
+
static int cs_etm__init_traceid_queue(struct cs_etm_queue *etmq,
struct cs_etm_traceid_queue *tidq,
u8 trace_chan_id)
@@ -458,15 +509,15 @@ static int cs_etm__flush_events(struct perf_session *session,
if (!tool->ordered_events)
return -EINVAL;

- if (!etm->timeless_decoding)
- return -EINVAL;
-
ret = cs_etm__update_queues(etm);

if (ret < 0)
return ret;

- return cs_etm__process_timeless_queues(etm, -1);
+ if (etm->timeless_decoding)
+ return cs_etm__process_timeless_queues(etm, -1);
+
+ return cs_etm__process_queues(etm);
}

static void cs_etm__free_traceid_queues(struct cs_etm_queue *etmq)
@@ -685,6 +736,9 @@ static int cs_etm__setup_queue(struct cs_etm_auxtrace *etm,
unsigned int queue_nr)
{
int ret = 0;
+ unsigned int cs_queue_nr;
+ u8 trace_chan_id;
+ u64 timestamp;
struct cs_etm_queue *etmq = queue->priv;

if (list_empty(&queue->head) || etmq)
@@ -702,6 +756,67 @@ static int cs_etm__setup_queue(struct cs_etm_auxtrace *etm,
etmq->queue_nr = queue_nr;
etmq->offset = 0;

+ if (etm->timeless_decoding)
+ goto out;
+
+ /*
+ * We are under a CPU-wide trace scenario. As such we need to know
+ * when the code that generated the traces started to execute so that
+ * it can be correlated with execution on other CPUs. So we get a
+ * handle on the beginning of traces and decode until we find a
+ * timestamp. The timestamp is then added to the auxtrace min heap
+ * in order to know what nibble (of all the etmqs) to decode first.
+ */
+ while (1) {
+ /*
+ * Fetch an aux_buffer from this etmq. Bail if no more
+ * blocks or an error has been encountered.
+ */
+ ret = cs_etm__get_data_block(etmq);
+ if (ret <= 0)
+ goto out;
+
+ /*
+ * Run decoder on the trace block. The decoder will stop when
+ * encountering a timestamp, a full packet queue or the end of
+ * trace for that block.
+ */
+ ret = cs_etm__decode_data_block(etmq);
+ if (ret)
+ goto out;
+
+ /*
+ * Function cs_etm_decoder__do_{hard|soft}_timestamp() does all
+ * the timestamp calculation for us.
+ */
+ timestamp = cs_etm__etmq_get_timestamp(etmq, &trace_chan_id);
+
+ /* We found a timestamp, no need to continue. */
+ if (timestamp)
+ break;
+
+ /*
+ * We didn't find a timestamp so empty all the traceid packet
+ * queues before looking for another timestamp packet, either
+ * in the current data block or a new one. Packets that were
+ * just decoded are useless since no timestamp has been
+ * associated with them. As such simply discard them.
+ */
+ cs_etm__clear_all_packet_queues(etmq);
+ }
+
+ /*
+ * We have a timestamp. Add it to the min heap to reflect when
+ * instructions conveyed by the range packets of this traceID queue
+ * started to execute. Once the same has been done for all the traceID
+ * queues of each etmq, redenring and decoding can start in
+ * chronological order.
+ *
+ * Note that packets decoded above are still in the traceID's packet
+ * queue and will be processed in cs_etm__process_queues().
+ */
+ cs_queue_nr = TO_CS_QUEUE_NR(queue_nr, trace_id_chan);
+ ret = auxtrace_heap__add(&etm->heap, cs_queue_nr, timestamp);
out:
return ret;
}
@@ -1846,6 +1961,28 @@ static int cs_etm__process_traceid_queue(struct cs_etm_queue *etmq,
return ret;
}

+static void cs_etm__clear_all_traceid_queues(struct cs_etm_queue *etmq)
+{
+ int idx;
+ struct int_node *inode;
+ struct cs_etm_traceid_queue *tidq;
+ struct intlist *traceid_queues_list = etmq->traceid_queues_list;
+
+ intlist__for_each_entry(inode, traceid_queues_list) {
+ idx = (int)(intptr_t)inode->priv;
+ tidq = etmq->traceid_queues[idx];
+
+ /* Ignore return value */
+ cs_etm__process_traceid_queue(etmq, tidq);
+
+ /*
+ * Generate an instruction sample with the remaining
+ * branchstack entries.
+ */
+ cs_etm__flush(etmq, tidq);
+ }
+}
+
static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
{
int err = 0;
@@ -1913,6 +2050,105 @@ static int cs_etm__process_timeless_queues(struct cs_etm_auxtrace *etm,
return 0;
}

+static int cs_etm__process_queues(struct cs_etm_auxtrace *etm)
+{
+ int ret = 0;
+ unsigned int cs_queue_nr, queue_nr;
+ u8 trace_chan_id;
+ u64 timestamp;
+ struct auxtrace_queue *queue;
+ struct cs_etm_queue *etmq;
+ struct cs_etm_traceid_queue *tidq;
+
+ while (1) {
+ if (!etm->heap.heap_cnt)
+ goto out;
+
+ /* Take the entry at the top of the min heap */
+ cs_queue_nr = etm->heap.heap_array[0].queue_nr;
+ queue_nr = TO_QUEUE_NR(cs_queue_nr);
+ trace_chan_id = TO_TRACE_CHAN_ID(cs_queue_nr);
+ queue = &etm->queues.queue_array[queue_nr];
+ etmq = queue->priv;
+
+ /*
+ * Remove the top entry from the heap since we are about
+ * to process it.
+ */
+ auxtrace_heap__pop(&etm->heap);
+
+ tidq = cs_etm__etmq_get_traceid_queue(etmq, trace_chan_id);
+ if (!tidq) {
+ /*
+ * No traceID queue has been allocated for this traceID,
+ * which means something somewhere went very wrong. No
+ * other choice than simply exit.
+ */
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /*
+ * Packets associated with this timestamp are already in
+ * the etmq's traceID queue, so process them.
+ */
+ ret = cs_etm__process_traceid_queue(etmq, tidq);
+ if (ret < 0)
+ goto out;
+
+ /*
+ * Packets for this timestamp have been processed, time to
+ * move on to the next timestamp, fetching a new auxtrace_buffer
+ * if need be.
+ */
+refetch:
+ ret = cs_etm__get_data_block(etmq);
+ if (ret < 0)
+ goto out;
+
+ /*
+ * No more auxtrace_buffers to process in this etmq, simply
+ * move on to another entry in the auxtrace_heap.
+ */
+ if (!ret)
+ continue;
+
+ ret = cs_etm__decode_data_block(etmq);
+ if (ret)
+ goto out;
+
+ timestamp = cs_etm__etmq_get_timestamp(etmq, &trace_chan_id);
+
+ if (!timestamp) {
+ /*
+ * Function cs_etm__decode_data_block() returns when
+ * there is no more traces to decode in the current
+ * auxtrace_buffer OR when a timestamp has been
+ * encountered on any of the traceID queues. Since we
+ * did not get a timestamp, there is no more traces to
+ * process in this auxtrace_buffer. As such empty and
+ * flush all traceID queues.
+ */
+ cs_etm__clear_all_traceid_queues(etmq);
+
+ /* Fetch another auxtrace_buffer for this etmq */
+ goto refetch;
+ }
+
+ /*
+ * Add to the min heap the timestamp for packets that have
+ * just been decoded. They will be processed and synthesized
+ * during the next call to cs_etm__process_traceid_queue() for
+ * this queue/traceID.
+ */
+ cs_queue_nr = TO_CS_QUEUE_NR(queue_nr, trace_chan_id);
+ ret = auxtrace_heap__add(&etm->heap, cs_queue_nr, timestamp);
+ }
+
+out:
+ return ret;
+}
+
static int cs_etm__process_itrace_start(struct cs_etm_auxtrace *etm,
union perf_event *event)
{
@@ -1991,9 +2227,6 @@ static int cs_etm__process_event(struct perf_session *session,
return -EINVAL;
}

- if (!etm->timeless_decoding)
- return -EINVAL;
-
if (sample->time && (sample->time != (u64) -1))
timestamp = sample->time;
else
@@ -2005,7 +2238,8 @@ static int cs_etm__process_event(struct perf_session *session,
return err;
}

- if (event->header.type == PERF_RECORD_EXIT)
+ if (etm->timeless_decoding &&
+ event->header.type == PERF_RECORD_EXIT)
return cs_etm__process_timeless_queues(etm,
event->fork.tid);

@@ -2014,6 +2248,10 @@ static int cs_etm__process_event(struct perf_session *session,
else if (event->header.type == PERF_RECORD_SWITCH_CPU_WIDE)
return cs_etm__process_switch_cpu_wide(etm, event);

+ if (!etm->timeless_decoding &&
+ event->header.type == PERF_RECORD_AUX)
+ return cs_etm__process_queues(etm);
+
return 0;
}

--
2.20.1
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