[RFC/PATCH] perf record: Save build-id of DSO in callchains

[Namhyung Kim]

Currently the build-id only recorded for sampled location, but in
order to correctly view/annotate callchains it might need the
build-id's of callchains too.  I guess this choice was due to a
performance impact on the post-processing at perf record time.

Add a new option --buildid-callchain to record this info.

$ perf record -o xxx -g -- perf > /dev/null
$ perf buildid-list -i xxx
6ebcee76c4b04895598b4df86ec445c49fc137a2 /lib/modules/3.18.6-1-ARCH/build/vmlinux
fc0759b71584d2513b04f1b530965a61b5e499e2 /usr/lib/ld-2.21.so

$ perf record -o yyy -g --buildid-callchain -- perf > /dev/null
$ perf buildid-list -i yyy
6ebcee76c4b04895598b4df86ec445c49fc137a2 /lib/modules/3.18.6-1-ARCH/build/vmlinux
4235ae90856f98d2746529648a3339ebfa6ede43 /home/namhyung/project/linux/tools/perf/perf
fc0759b71584d2513b04f1b530965a61b5e499e2 /usr/lib/ld-2.21.so
9ac81172d5ff96f40d984fe7c10073a98f1a6b2e /usr/lib/libc-2.21.so
864583bb881db1d260660a30a51b3f5022cd538b /usr/lib/libnuma.so.1.0.0

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/builtin-record.c |  2 ++
 tools/perf/util/build-id.c  | 24 +++++++++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 5a2ff510b75b..a43b1d96714b 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -841,6 +841,8 @@ struct option __record_options[] = {
 		    "Sample machine registers on interrupt"),
 	OPT_BOOLEAN(0, "running-time", &record.opts.running_time,
 		    "Record running/enabled time of read (:S) events"),
+	OPT_BOOLEAN(0, "buildid-callchain", &symbol_conf.use_callchain,
+		    "Record build-id of DSOs in callchain"),
 	OPT_END()
 };
 
diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index f7fb2587df69..401357f3425a 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -17,6 +17,7 @@
 #include "tool.h"
 #include "header.h"
 #include "vdso.h"
+#include "callchain.h"
 
 
 static bool no_buildid_cache;
@@ -24,13 +25,15 @@ static bool no_buildid_cache;
 int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
 			   union perf_event *event,
 			   struct perf_sample *sample,
-			   struct perf_evsel *evsel __maybe_unused,
+			   struct perf_evsel *evsel,
 			   struct machine *machine)
 {
 	struct addr_location al;
 	u8 cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;
 	struct thread *thread = machine__findnew_thread(machine, sample->pid,
 							sample->tid);
+	int err;
+	struct callchain_cursor_node *node;
 
 	if (thread == NULL) {
 		pr_err("problem processing %d event, skipping it.\n",
@@ -43,6 +46,25 @@ int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
 	if (al.map != NULL)
 		al.map->dso->hit = 1;
 
+	if (!symbol_conf.use_callchain)
+		return 0;
+
+	err = sample__resolve_callchain(sample, NULL, evsel, &al,
+					PERF_MAX_STACK_DEPTH);
+	if (err)
+		return err;
+
+	callchain_cursor_commit(&callchain_cursor);
+	node = callchain_cursor_current(&callchain_cursor);
+
+	while (node) {
+		if (node->map)
+			node->map->dso->hit = 1;
+
+		callchain_cursor_advance(&callchain_cursor);
+		node = callchain_cursor_current(&callchain_cursor);
+	}
+
 	return 0;
 }
 
-- 
2.3.3

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