[PATCH V6 08/25] perf session: Add hooks to allow transparent decoding of AUX area tracing data

[Adrian Hunter]

Hook into session processing so that AUX area decoding can
synthesize events transparently to the tools.

The advantages of transparent decoding are that tools can be used
directly with perf.data files containing AUX area tracing data,
which is easier for the user and more efficient than having a
separate decoding tool.

This will work as follows:
1. Tools will feed auxtrace events to the decoder using
perf_tool->auxtrace() (support for that still to come).
2. The decoder can process side-band events as needed due
to the auxtrace->process_event() hook.
3. The decoder can deliver synthesized events into the
event stream using perf_session__deliver_synth_event().

Note the expectation is that decoding will work on data that is
time-ordered with respect to the per-cpu or per-thread contexts
that were recorded.

Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
 tools/perf/util/auxtrace.h | 55 ++++++++++++++++++++++++++++++++++++
 tools/perf/util/session.c  | 70 +++++++++++++++++++++++++++++++++++-----------
 tools/perf/util/session.h  |  3 ++
 3 files changed, 111 insertions(+), 17 deletions(-)

diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index 6b433e6..909df80 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -23,6 +23,7 @@
 #include <linux/types.h>
 
 #include "../perf.h"
+#include "session.h"
 
 union perf_event;
 struct perf_session;
@@ -32,6 +33,24 @@ struct record_opts;
 struct auxtrace_info_event;
 
 /**
+ * struct auxtrace - session callbacks to allow AUX area data decoding.
+ * @process_event: lets the decoder see all session events
+ * @flush_events: process any remaining data
+ * @free_events: free resources associated with event processing
+ * @free: free resources associated with the session
+ */
+struct auxtrace {
+	int (*process_event)(struct perf_session *session,
+			     union perf_event *event,
+			     struct perf_sample *sample,
+			     struct perf_tool *tool);
+	int (*flush_events)(struct perf_session *session,
+			    struct perf_tool *tool);
+	void (*free_events)(struct perf_session *session);
+	void (*free)(struct perf_session *session);
+};
+
+/**
  * struct auxtrace_mmap - records an mmap of the auxtrace buffer.
  * @base: address of mapped area
  * @userpg: pointer to buffer's perf_event_mmap_page
@@ -152,4 +171,40 @@ int perf_event__synthesize_auxtrace(struct perf_tool *tool,
 				    size_t size, u64 offset, u64 ref, int idx,
 				    u32 tid, u32 cpu);
 
+static inline int auxtrace__process_event(struct perf_session *session,
+					  union perf_event *event,
+					  struct perf_sample *sample,
+					  struct perf_tool *tool)
+{
+	if (!session->auxtrace)
+		return 0;
+
+	return session->auxtrace->process_event(session, event, sample, tool);
+}
+
+static inline int auxtrace__flush_events(struct perf_session *session,
+					 struct perf_tool *tool)
+{
+	if (!session->auxtrace)
+		return 0;
+
+	return session->auxtrace->flush_events(session, tool);
+}
+
+static inline void auxtrace__free_events(struct perf_session *session)
+{
+	if (!session->auxtrace)
+		return;
+
+	return session->auxtrace->free_events(session);
+}
+
+static inline void auxtrace__free(struct perf_session *session)
+{
+	if (!session->auxtrace)
+		return;
+
+	return session->auxtrace->free(session);
+}
+
 #endif
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index b4cac8b..918554d 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -15,12 +15,7 @@
 #include "cpumap.h"
 #include "perf_regs.h"
 #include "asm/bug.h"
-
-static int machines__deliver_event(struct machines *machines,
-				   struct perf_evlist *evlist,
-				   union perf_event *event,
-				   struct perf_sample *sample,
-				   struct perf_tool *tool, u64 file_offset);
+#include "auxtrace.h"
 
 static int perf_session__open(struct perf_session *session)
 {
@@ -92,13 +87,9 @@ static void perf_session__set_comm_exec(struct perf_session *session)
 	machines__set_comm_exec(&session->machines, comm_exec);
 }
 
-static int ordered_events__deliver_event(struct ordered_events *oe,
-					 struct ordered_event *event,
-					 struct perf_sample *sample)
-{
-	return machines__deliver_event(oe->machines, oe->evlist, event->event,
-				       sample, oe->tool, event->file_offset);
-}
+static int perf_session__deliver_ordered_event(struct ordered_events *oe,
+					       struct ordered_event *event,
+					       struct perf_sample *sample);
 
 struct perf_session *perf_session__new(struct perf_data_file *file,
 				       bool repipe, struct perf_tool *tool)
@@ -141,7 +132,8 @@ struct perf_session *perf_session__new(struct perf_data_file *file,
 		tool->ordered_events = false;
 	} else {
 		ordered_events__init(&session->ordered_events, &session->machines,
-				     session->evlist, tool, ordered_events__deliver_event);
+				     session->evlist, tool,
+				     perf_session__deliver_ordered_event);
 	}
 
 	return session;
@@ -177,6 +169,7 @@ static void perf_session_env__delete(struct perf_session_env *env)
 
 void perf_session__delete(struct perf_session *session)
 {
+	auxtrace__free(session);
 	perf_session__destroy_kernel_maps(session);
 	perf_session__delete_threads(session);
 	perf_session_env__delete(&session->header.env);
@@ -1022,6 +1015,35 @@ static int machines__deliver_event(struct machines *machines,
 	}
 }
 
+static int perf_session__deliver_event(struct perf_session *session,
+				       union perf_event *event,
+				       struct perf_sample *sample,
+				       struct perf_tool *tool,
+				       u64 file_offset)
+{
+	int ret;
+
+	ret = auxtrace__process_event(session, event, sample, tool);
+	if (ret < 0)
+		return ret;
+	if (ret > 0)
+		return 0;
+
+	return machines__deliver_event(&session->machines, session->evlist,
+				       event, sample, tool, file_offset);
+}
+
+static int perf_session__deliver_ordered_event(struct ordered_events *oe,
+					       struct ordered_event *event,
+					       struct perf_sample *sample)
+{
+	struct perf_session *session =
+			container_of(oe, struct perf_session, ordered_events);
+
+	return perf_session__deliver_event(session, event->event, sample,
+					   oe->tool, event->file_offset);
+}
+
 static s64 perf_session__process_user_event(struct perf_session *session,
 					    union perf_event *event,
 					    u64 file_offset)
@@ -1182,8 +1204,8 @@ static s64 perf_session__process_event(struct perf_session *session,
 			return ret;
 	}
 
-	return machines__deliver_event(&session->machines, evlist, event,
-				       &sample, tool, file_offset);
+	return perf_session__deliver_event(session, event, &sample, tool,
+					   file_offset);
 }
 
 void perf_event_header__bswap(struct perf_event_header *hdr)
@@ -1340,10 +1362,14 @@ more:
 done:
 	/* do the final flush for ordered samples */
 	err = ordered_events__flush(oe, OE_FLUSH__FINAL);
+	if (err)
+		goto out_err;
+	err = auxtrace__flush_events(session, tool);
 out_err:
 	free(buf);
 	perf_tool__warn_about_errors(tool, &session->evlist->stats);
 	ordered_events__free(&session->ordered_events);
+	auxtrace__free_events(session);
 	return err;
 }
 
@@ -1486,10 +1512,14 @@ more:
 out:
 	/* do the final flush for ordered samples */
 	err = ordered_events__flush(oe, OE_FLUSH__FINAL);
+	if (err)
+		goto out_err;
+	err = auxtrace__flush_events(session, tool);
 out_err:
 	ui_progress__finish();
 	perf_tool__warn_about_errors(tool, &session->evlist->stats);
 	ordered_events__free(&session->ordered_events);
+	auxtrace__free_events(session);
 	session->one_mmap = false;
 	return err;
 }
@@ -1569,7 +1599,13 @@ size_t perf_session__fprintf_dsos_buildid(struct perf_session *session, FILE *fp
 
 size_t perf_session__fprintf_nr_events(struct perf_session *session, FILE *fp)
 {
-	size_t ret = fprintf(fp, "Aggregated stats:\n");
+	size_t ret;
+	const char *msg = "";
+
+	if (perf_header__has_feat(&session->header, HEADER_AUXTRACE))
+		msg = " (excludes AUX area (e.g. instruction trace) decoded / synthesized events)";
+
+	ret = fprintf(fp, "Aggregated stats:%s\n", msg);
 
 	ret += events_stats__fprintf(&session->evlist->stats, fp);
 	return ret;
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index 1310998..8575d6f 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -15,10 +15,13 @@
 struct ip_callchain;
 struct thread;
 
+struct auxtrace;
+
 struct perf_session {
 	struct perf_header	header;
 	struct machines		machines;
 	struct perf_evlist	*evlist;
+	struct auxtrace		*auxtrace;
 	struct trace_event	tevent;
 	bool			repipe;
 	bool			one_mmap;
-- 
1.9.1

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