2 files changed, 71 insertions, 8 deletions

diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 89b390623b63..3ca5d9399680 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -2006,14 +2006,6 @@ int perf_event__synthesize_stat_events(struct perf_stat_config *config, struct p
 	return 0;
 }
 
-int __weak perf_event__synth_time_conv(const struct perf_event_mmap_page *pc __maybe_unused,
-				       struct perf_tool *tool __maybe_unused,
-				       perf_event__handler_t process __maybe_unused,
-				       struct machine *machine __maybe_unused)
-{
-	return 0;
-}
-
 extern const struct perf_header_feature_ops feat_ops[HEADER_LAST_FEATURE];
 
 int perf_event__synthesize_features(struct perf_tool *tool, struct perf_session *session,
diff --git a/tools/perf/util/tsc.c b/tools/perf/util/tsc.c
index bfa782421cbd..9e3f04ddddf8 100644
--- a/tools/perf/util/tsc.c
+++ b/tools/perf/util/tsc.c
@@ -1,7 +1,16 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+
 #include <linux/compiler.h>
+#include <linux/perf_event.h>
+#include <linux/stddef.h>
 #include <linux/types.h>
 
+#include <asm/barrier.h>
+
+#include "event.h"
+#include "synthetic-events.h"
+#include "debug.h"
 #include "tsc.h"
 
 u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
@@ -25,6 +34,68 @@ u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
 	       ((rem * tc->time_mult) >> tc->time_shift);
 }
 
+int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
+			     struct perf_tsc_conversion *tc)
+{
+	bool cap_user_time_zero;
+	u32 seq;
+	int i = 0;
+
+	while (1) {
+		seq = pc->lock;
+		rmb();
+		tc->time_mult = pc->time_mult;
+		tc->time_shift = pc->time_shift;
+		tc->time_zero = pc->time_zero;
+		cap_user_time_zero = pc->cap_user_time_zero;
+		rmb();
+		if (pc->lock == seq && !(seq & 1))
+			break;
+		if (++i > 10000) {
+			pr_debug("failed to get perf_event_mmap_page lock\n");
+			return -EINVAL;
+		}
+	}
+
+	if (!cap_user_time_zero)
+		return -EOPNOTSUPP;
+
+	return 0;
+}
+
+int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc,
+				struct perf_tool *tool,
+				perf_event__handler_t process,
+				struct machine *machine)
+{
+	union perf_event event = {
+		.time_conv = {
+			.header = {
+				.type = PERF_RECORD_TIME_CONV,
+				.size = sizeof(struct perf_record_time_conv),
+			},
+		},
+	};
+	struct perf_tsc_conversion tc;
+	int err;
+
+	if (!pc)
+		return 0;
+	err = perf_read_tsc_conversion(pc, &tc);
+	if (err == -EOPNOTSUPP)
+		return 0;
+	if (err)
+		return err;
+
+	pr_debug2("Synthesizing TSC conversion information\n");
+
+	event.time_conv.time_mult  = tc.time_mult;
+	event.time_conv.time_shift = tc.time_shift;
+	event.time_conv.time_zero  = tc.time_zero;
+
+	return process(tool, &event, NULL, machine);
+}
+
 u64 __weak rdtsc(void)
 {
 	return 0;