[PATCH 09/14] perf cs-etm: Queue partial AUX records

[James Clark]

In snapshot mode AUX records may straddle the boundary of multiple trace
buffers. Currently we only queue AUX records whose range is contained
wholly within a single buffer.

Fix it by queuing any partial AUX range that overlaps any buffer.

Signed-off-by: James Clark <james.clark at linaro.org>
---
 tools/perf/util/cs-etm.c | 54 +++++++++++++++++++++++++++---------------------
 1 file changed, 30 insertions(+), 24 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 28f5ce63ba80..5bafee31cf4b 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -3197,7 +3197,8 @@ static int cs_etm__queue_aux_fragment(struct perf_session *session, off_t file_o
 	union perf_event *auxtrace_event_union;
 	struct perf_record_auxtrace *auxtrace_event;
 	union perf_event auxtrace_fragment;
-	__u64 aux_offset, aux_size;
+	__u64 aux_start, aux_end, auxtrace_start, auxtrace_end;
+	__u64 frag_start, frag_end, frag_size;
 	enum cs_etm_format format;
 
 	struct cs_etm_auxtrace *etm = container_of(session->auxtrace,
@@ -3245,42 +3246,41 @@ static int cs_etm__queue_aux_fragment(struct perf_session *session, off_t file_o
 	}
 
 	if (aux_event->flags & PERF_AUX_FLAG_OVERWRITE) {
-		/*
-		 * Clamp size in snapshot mode. The buffer size is clamped in
-		 * __auxtrace_mmap__read() for snapshots, so the aux record size doesn't reflect
-		 * the buffer size.
-		 */
-		aux_size = min(aux_event->aux_size, auxtrace_event->size);
-
 		/*
 		 * In this mode, the head also points to the end of the buffer so aux_offset
 		 * needs to have the size subtracted so it points to the beginning as in normal mode
 		 */
-		aux_offset = aux_event->aux_offset - aux_size;
+		aux_start = aux_event->aux_offset - aux_event->aux_size;
+		aux_end = aux_event->aux_offset;
 	} else {
-		aux_size = aux_event->aux_size;
-		aux_offset = aux_event->aux_offset;
+		aux_start = aux_event->aux_offset;
+		aux_end = aux_event->aux_offset + aux_event->aux_size;
 	}
 
-	if (aux_offset >= auxtrace_event->offset &&
-	    aux_offset + aux_size <= auxtrace_event->offset + auxtrace_event->size) {
+	auxtrace_start = auxtrace_event->offset;
+	auxtrace_end = auxtrace_start + auxtrace_event->size;
+	frag_start = max(aux_start, auxtrace_start);
+	frag_end = min(aux_end, auxtrace_end);
+
+	if (frag_start < frag_end) {
 		struct cs_etm_queue *etmq = cs_etm__get_queue(etm, sample->cpu);
 
 		if (!etmq)
 			return -EINVAL;
 
 		/*
-		 * If this AUX event was inside this buffer somewhere, create a new auxtrace event
-		 * based on the sizes of the aux event, and queue that fragment.
+		 * If this AUX event overlaps this buffer, create a new auxtrace event
+		 * for the overlapping range and queue that fragment.
 		 */
+		frag_size = frag_end - frag_start;
 		auxtrace_fragment.auxtrace = *auxtrace_event;
-		auxtrace_fragment.auxtrace.size = aux_size;
-		auxtrace_fragment.auxtrace.offset = aux_offset;
+		auxtrace_fragment.auxtrace.size = frag_size;
+		auxtrace_fragment.auxtrace.offset = frag_start;
 		auxtrace_fragment.auxtrace.idx = etmq->queue_nr;
-		file_offset += aux_offset - auxtrace_event->offset + auxtrace_event->header.size;
+		file_offset += frag_start - auxtrace_start + auxtrace_event->header.size;
 
 		pr_debug3("CS ETM: Queue buffer size: %#"PRI_lx64" offset: %#"PRI_lx64
-			  " tid: %d cpu: %d\n", aux_size, aux_offset, sample->tid, sample->cpu);
+			  " tid: %d cpu: %d\n", frag_size, frag_start, sample->tid, sample->cpu);
 		err = auxtrace_queues__add_event(&etm->queues, session, &auxtrace_fragment,
 						 file_offset, NULL);
 		if (err)
@@ -3320,6 +3320,7 @@ static int cs_etm__queue_aux_records_cb(struct perf_session *session, union perf
 	struct auxtrace_index *auxtrace_index;
 	struct evsel *evsel;
 	size_t i;
+	bool found = false;
 
 	/* Don't care about any other events, we're only queuing buffers for AUX events */
 	if (event->header.type != PERF_RECORD_AUX)
@@ -3353,11 +3354,14 @@ static int cs_etm__queue_aux_records_cb(struct perf_session *session, union perf
 			ret = cs_etm__queue_aux_fragment(session, ent->file_offset,
 							 ent->sz, &event->aux, &sample);
 			/*
-			 * Stop search on error or successful values. Continue search on
-			 * 1 ('not found')
+			 * Stop search on error values. Continue search on
+			 * 1 ('not found') or 0 ('queued')
 			 */
-			if (ret != 1)
+			if (ret < 0)
 				goto out;
+
+			if (!ret)
+				found = true;
 		}
 	}
 
@@ -3365,8 +3369,10 @@ static int cs_etm__queue_aux_records_cb(struct perf_session *session, union perf
 	 * Couldn't find the buffer corresponding to this aux record, something went wrong. Warn but
 	 * don't exit with an error because it will still be possible to decode other aux records.
 	 */
-	pr_err("CS ETM: Couldn't find auxtrace buffer for aux_offset: %#"PRI_lx64
-	       " tid: %d cpu: %d\n", event->aux.aux_offset, sample.tid, sample.cpu);
+	if (!found) {
+		pr_err("CS ETM: Couldn't find auxtrace buffer for aux_offset: %#"PRI_lx64
+		       " tid: %d cpu: %d\n", event->aux.aux_offset, sample.tid, sample.cpu);
+	}
 	ret = 0;
 out:
 	perf_sample__exit(&sample);

-- 
2.43.0