5 files changed, 180 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
index b6472e463284..9ee96640744e 100644
--- a/tools/perf/Documentation/perf.data-file-format.txt
+++ b/tools/perf/Documentation/perf.data-file-format.txt
@@ -389,6 +389,19 @@ struct {
 Example:
  cpu pmu capabilities: branches=32, max_precise=3, pmu_name=icelake
 
+	HEADER_CLOCK_DATA = 29,
+
+	Contains clock id and its reference time together with wall clock
+	time taken at the 'same time', both values are in nanoseconds.
+	The format of data is as below.
+
+struct {
+	u32 version;  /* version = 1 */
+	u32 clockid;
+	u64 wall_clock_ns;
+	u64 clockid_time_ns;
+};
+
 	other bits are reserved and should ignored for now
 	HEADER_FEAT_BITS	= 256,
 
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index c9a07a1a75af..b21a8769db21 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -71,6 +71,7 @@
 #include <linux/time64.h>
 #include <linux/zalloc.h>
 #include <linux/bitmap.h>
+#include <sys/time.h>
 
 struct switch_output {
 	bool		 enabled;
@@ -1204,6 +1205,9 @@ static void record__init_features(struct record *rec)
 	if (!(rec->opts.use_clockid && rec->opts.clockid_res_ns))
 		perf_header__clear_feat(&session->header, HEADER_CLOCKID);
 
+	if (!rec->opts.use_clockid)
+		perf_header__clear_feat(&session->header, HEADER_CLOCK_DATA);
+
 	perf_header__clear_feat(&session->header, HEADER_DIR_FORMAT);
 	if (!record__comp_enabled(rec))
 		perf_header__clear_feat(&session->header, HEADER_COMPRESSED);
@@ -1552,6 +1556,40 @@ static int record__setup_sb_evlist(struct record *rec)
 	return 0;
 }
 
+static int record__init_clock(struct record *rec)
+{
+	struct perf_session *session = rec->session;
+	struct timespec ref_clockid;
+	struct timeval ref_tod;
+	u64 ref;
+
+	if (!rec->opts.use_clockid)
+		return 0;
+
+	session->header.env.clock.clockid = rec->opts.clockid;
+
+	if (gettimeofday(&ref_tod, NULL) != 0) {
+		pr_err("gettimeofday failed, cannot set reference time.\n");
+		return -1;
+	}
+
+	if (clock_gettime(rec->opts.clockid, &ref_clockid)) {
+		pr_err("clock_gettime failed, cannot set reference time.\n");
+		return -1;
+	}
+
+	ref = (u64) ref_tod.tv_sec * NSEC_PER_SEC +
+	      (u64) ref_tod.tv_usec * NSEC_PER_USEC;
+
+	session->header.env.clock.tod_ns = ref;
+
+	ref = (u64) ref_clockid.tv_sec * NSEC_PER_SEC +
+	      (u64) ref_clockid.tv_nsec;
+
+	session->header.env.clock.clockid_ns = ref;
+	return 0;
+}
+
 static int __cmd_record(struct record *rec, int argc, const char **argv)
 {
 	int err;
@@ -1632,6 +1670,9 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 		return -1;
 	}
 
+	if (record__init_clock(rec))
+		return -1;
+
 	record__init_features(rec);
 
 	if (rec->opts.use_clockid && rec->opts.clockid_res_ns)
diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
index 1ab2682d5d2b..7218f7db57af 100644
--- a/tools/perf/util/env.h
+++ b/tools/perf/util/env.h
@@ -100,6 +100,18 @@ struct perf_env {
 	/* For fast cpu to numa node lookup via perf_env__numa_node */
 	int			*numa_map;
 	int			 nr_numa_map;
+
+	/* For real clock time reference. */
+	struct {
+		u64	tod_ns;
+		u64	clockid_ns;
+		int	clockid;
+		/*
+		 * enabled is valid for report mode, and is true if above
+		 * values are set, it's set in process_clock_data
+		 */
+		bool	enabled;
+	} clock;
 };
 
 enum perf_compress_type {
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 7a67d017d72c..eece94cf6f86 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -46,6 +46,7 @@
 #include "util/util.h" // perf_exe()
 #include "cputopo.h"
 #include "bpf-event.h"
+#include "clockid.h"
 
 #include <linux/ctype.h>
 #include <internal/lib.h>
@@ -895,6 +896,40 @@ static int write_clockid(struct feat_fd *ff,
 			sizeof(ff->ph->env.clockid_res_ns));
 }
 
+static int write_clock_data(struct feat_fd *ff,
+			    struct evlist *evlist __maybe_unused)
+{
+	u64 *data64;
+	u32 data32;
+	int ret;
+
+	/* version */
+	data32 = 1;
+
+	ret = do_write(ff, &data32, sizeof(data32));
+	if (ret < 0)
+		return ret;
+
+	/* clockid */
+	data32 = ff->ph->env.clock.clockid;
+
+	ret = do_write(ff, &data32, sizeof(data32));
+	if (ret < 0)
+		return ret;
+
+	/* TOD ref time */
+	data64 = &ff->ph->env.clock.tod_ns;
+
+	ret = do_write(ff, data64, sizeof(*data64));
+	if (ret < 0)
+		return ret;
+
+	/* clockid ref time */
+	data64 = &ff->ph->env.clock.clockid_ns;
+
+	return do_write(ff, data64, sizeof(*data64));
+}
+
 static int write_dir_format(struct feat_fd *ff,
 			    struct evlist *evlist __maybe_unused)
 {
@@ -1549,6 +1584,49 @@ static void print_clockid(struct feat_fd *ff, FILE *fp)
 		ff->ph->env.clockid_res_ns * 1000);
 }
 
+static void print_clock_data(struct feat_fd *ff, FILE *fp)
+{
+	struct timespec clockid_ns;
+	char tstr[64], date[64];
+	struct timeval tod_ns;
+	clockid_t clockid;
+	struct tm ltime;
+	u64 ref;
+
+	if (!ff->ph->env.clock.enabled) {
+		fprintf(fp, "# reference time disabled\n");
+		return;
+	}
+
+	/* Compute TOD time. */
+	ref = ff->ph->env.clock.tod_ns;
+	tod_ns.tv_sec = ref / NSEC_PER_SEC;
+	ref -= tod_ns.tv_sec * NSEC_PER_SEC;
+	tod_ns.tv_usec = ref / NSEC_PER_USEC;
+
+	/* Compute clockid time. */
+	ref = ff->ph->env.clock.clockid_ns;
+	clockid_ns.tv_sec = ref / NSEC_PER_SEC;
+	ref -= clockid_ns.tv_sec * NSEC_PER_SEC;
+	clockid_ns.tv_nsec = ref;
+
+	clockid = ff->ph->env.clock.clockid;
+
+	if (localtime_r(&tod_ns.tv_sec, &ltime) == NULL)
+		snprintf(tstr, sizeof(tstr), "<error>");
+	else {
+		strftime(date, sizeof(date), "%F %T", &ltime);
+		scnprintf(tstr, sizeof(tstr), "%s.%06d",
+			  date, (int) tod_ns.tv_usec);
+	}
+
+	fprintf(fp, "# clockid: %s (%u)\n", clockid_name(clockid), clockid);
+	fprintf(fp, "# reference time: %s = %ld.%06d (TOD) = %ld.%09ld (%s)\n",
+		    tstr, tod_ns.tv_sec, (int) tod_ns.tv_usec,
+		    clockid_ns.tv_sec, clockid_ns.tv_nsec,
+		    clockid_name(clockid));
+}
+
 static void print_dir_format(struct feat_fd *ff, FILE *fp)
 {
 	struct perf_session *session;
@@ -2738,6 +2816,40 @@ static int process_clockid(struct feat_fd *ff,
 	return 0;
 }
 
+static int process_clock_data(struct feat_fd *ff,
+			      void *_data __maybe_unused)
+{
+	u32 data32;
+	u64 data64;
+
+	/* version */
+	if (do_read_u32(ff, &data32))
+		return -1;
+
+	if (data32 != 1)
+		return -1;
+
+	/* clockid */
+	if (do_read_u32(ff, &data32))
+		return -1;
+
+	ff->ph->env.clock.clockid = data32;
+
+	/* TOD ref time */
+	if (do_read_u64(ff, &data64))
+		return -1;
+
+	ff->ph->env.clock.tod_ns = data64;
+
+	/* clockid ref time */
+	if (do_read_u64(ff, &data64))
+		return -1;
+
+	ff->ph->env.clock.clockid_ns = data64;
+	ff->ph->env.clock.enabled = true;
+	return 0;
+}
+
 static int process_dir_format(struct feat_fd *ff,
 			      void *_data __maybe_unused)
 {
@@ -3008,6 +3120,7 @@ const struct perf_header_feature_ops feat_ops[HEADER_LAST_FEATURE] = {
 	FEAT_OPR(BPF_BTF,       bpf_btf,        false),
 	FEAT_OPR(COMPRESSED,	compressed,	false),
 	FEAT_OPR(CPU_PMU_CAPS,	cpu_pmu_caps,	false),
+	FEAT_OPR(CLOCK_DATA,	clock_data,	false),
 };
 
 struct header_print_data {
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 650bd1c7a99b..2aca71763ecf 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -44,6 +44,7 @@ enum {
 	HEADER_BPF_BTF,
 	HEADER_COMPRESSED,
 	HEADER_CPU_PMU_CAPS,
+	HEADER_CLOCK_DATA,
 	HEADER_LAST_FEATURE,
 	HEADER_FEAT_BITS	= 256,
 };