linux-kernel - [PATCH v2 2/4] perf tools: add a mechanism to inject stack frames

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Message-Id: <20210210132213.8146-2-alexandre.truong@arm.com>
Date:   Wed, 10 Feb 2021 13:22:11 +0000
From:   Alexandre Truong <alexandre.truong@....com>
To:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Cc:     Alexandre Truong <alexandre.truong@....com>
Subject: [PATCH v2 2/4] perf tools: add a mechanism to inject stack frames

Add a mechanism for platforms to inject stack frames for the leaf
frame caller if there is enough information to determine a frame
is missing from dwarf or other post processing mechanisms.

Signed-off-by: Alexandre Truong <alexandre.truong@....com>
---
 tools/perf/util/machine.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 522ea3236bcc..40082d70eec1 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2671,6 +2671,12 @@ static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread,
 	return err;
 }
 
+static u64 get_leaf_frame_caller(struct perf_sample *sample __maybe_unused,
+		struct thread *thread __maybe_unused)
+{
+	return 0;
+}
+
 static int thread__resolve_callchain_sample(struct thread *thread,
 					    struct callchain_cursor *cursor,
 					    struct evsel *evsel,
@@ -2687,6 +2693,8 @@ static int thread__resolve_callchain_sample(struct thread *thread,
 	int i, j, err, nr_entries;
 	int skip_idx = -1;
 	int first_call = 0;
+	u64 leaf_frame_caller;
+	int pos;
 
 	if (chain)
 		chain_nr = chain->nr;
@@ -2811,6 +2819,21 @@ static int thread__resolve_callchain_sample(struct thread *thread,
 			continue;
 		}
 
+		pos = callchain_param.order == ORDER_CALLEE ? 2 : chain_nr - 2;
+
+		if (i == pos) {
+			leaf_frame_caller = get_leaf_frame_caller(sample, thread);
+
+			if (leaf_frame_caller && leaf_frame_caller != ip) {
+
+				err = add_callchain_ip(thread, cursor, parent,
+					       root_al, &cpumode, leaf_frame_caller,
+					       false, NULL, NULL, 0);
+				if (err)
+					return (err < 0) ? err : 0;
+			}
+		}
+
 		err = add_callchain_ip(thread, cursor, parent,
 				       root_al, &cpumode, ip,
 				       false, NULL, NULL, 0);
-- 
2.23.0