linux-kernel - [PATCH v5 1/5] perf arm-spe: Save clock parameters from TIME

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Date:   Wed, 19 May 2021 15:19:35 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        James Clark <james.clark@....com>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Dave Martin <Dave.Martin@....com>, Al Grant <Al.Grant@....com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v5 1/5] perf arm-spe: Save clock parameters from TIME_CONV event

During the recording phase, "perf record" tool synthesizes event
PERF_RECORD_TIME_CONV for the hardware clock parameters and saves the
event into the data file.

Afterwards, when processing the data file, the event TIME_CONV will be
processed at the very early time and is stored into session context.

This patch extracts these parameters from the session context and saves
into the structure "spe->tc" with the type perf_tsc_conversion, so that
the parameters are ready for conversion between clock counter and time
stamp.

Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 tools/perf/util/arm-spe.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 2539d4baec44..d2ae5a5c13ee 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -26,6 +26,7 @@
 #include "symbol.h"
 #include "thread.h"
 #include "thread-stack.h"
+#include "tsc.h"
 #include "tool.h"
 #include "util/synthetic-events.h"
 
@@ -45,6 +46,8 @@ struct arm_spe {
 	struct machine			*machine;
 	u32				pmu_type;
 
+	struct perf_tsc_conversion	tc;
+
 	u8				timeless_decoding;
 	u8				data_queued;
 
@@ -1006,6 +1009,7 @@ int arm_spe_process_auxtrace_info(union perf_event *event,
 {
 	struct perf_record_auxtrace_info *auxtrace_info = &event->auxtrace_info;
 	size_t min_sz = sizeof(u64) * ARM_SPE_AUXTRACE_PRIV_MAX;
+	struct perf_record_time_conv *tc = &session->time_conv;
 	struct arm_spe *spe;
 	int err;
 
@@ -1027,6 +1031,28 @@ int arm_spe_process_auxtrace_info(union perf_event *event,
 	spe->pmu_type = auxtrace_info->priv[ARM_SPE_PMU_TYPE];
 
 	spe->timeless_decoding = arm_spe__is_timeless_decoding(spe);
+
+	/*
+	 * The synthesized event PERF_RECORD_TIME_CONV has been handled ahead
+	 * and the parameters for hardware clock are stored in the session
+	 * context.  Passes these parameters to the struct perf_tsc_conversion
+	 * in "spe->tc", which is used for later conversion between clock
+	 * counter and timestamp.
+	 *
+	 * For backward compatibility, copies the fields starting from
+	 * "time_cycles" only if they are contained in the event.
+	 */
+	spe->tc.time_shift = tc->time_shift;
+	spe->tc.time_mult = tc->time_mult;
+	spe->tc.time_zero = tc->time_zero;
+
+	if (event_contains(*tc, time_cycles)) {
+		spe->tc.time_cycles = tc->time_cycles;
+		spe->tc.time_mask = tc->time_mask;
+		spe->tc.cap_user_time_zero = tc->cap_user_time_zero;
+		spe->tc.cap_user_time_short = tc->cap_user_time_short;
+	}
+
 	spe->auxtrace.process_event = arm_spe_process_event;
 	spe->auxtrace.process_auxtrace_event = arm_spe_process_auxtrace_event;
 	spe->auxtrace.flush_events = arm_spe_flush;
-- 
2.25.1