linux-kernel - [PATCH RESEND v1 03/13] perf arm-spe: Refactor payload length calculation

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Date:   Mon, 17 Aug 2020 15:53:38 +0100
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        James Clark <james.clark@....com>,
        Will Deacon <will@...nel.org>, Al Grant <Al.Grant@....com>,
        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>,
        Wei Li <liwei391@...wei.com>, linux-kernel@...r.kernel.org,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Mike Leach <mike.leach@...aro.org>
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH RESEND v1 03/13] perf arm-spe: Refactor payload length calculation

Defines macro for payload length calculation instead of static function.

Currently the event packet's 'index' is assigned as payload length, but
the flow is not directive: it firstly gets the packet length (includes
header length and payload length) and then reduces header length from
packet length, so finally get the payload length; to simplify the code,
this patch directly assigns payload length to event packet's index.

Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 .../arm-spe-decoder/arm-spe-pkt-decoder.c     | 26 ++++++++-----------
 .../arm-spe-decoder/arm-spe-pkt-decoder.h     |  3 +++
 2 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
index 7c7b5eb09fba..5a8696031e16 100644
--- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
+++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
@@ -69,22 +69,20 @@ const char *arm_spe_pkt_name(enum arm_spe_pkt_type type)
 	return arm_spe_packet_name[type];
 }
 
-/* return ARM SPE payload size from its encoding,
- * which is in bits 5:4 of the byte.
- * 00 : byte
- * 01 : halfword (2)
- * 10 : word (4)
- * 11 : doubleword (8)
+/*
+ * Return ARM SPE payload size from header bits 5:4
+ *   00 : byte
+ *   01 : halfword (2)
+ *   10 : word (4)
+ *   11 : doubleword (8)
  */
-static int payloadlen(unsigned char byte)
-{
-	return 1 << ((byte & 0x30) >> 4);
-}
+#define PAYLOAD_LEN(val)	\
+	(1 << (((val) & SPE_HEADER_SZ_MASK) >> SPE_HEADER_SZ_SHIFT))
 
 static int arm_spe_get_payload(const unsigned char *buf, size_t len,
 			       struct arm_spe_pkt *packet)
 {
-	size_t payload_len = payloadlen(buf[0]);
+	size_t payload_len = PAYLOAD_LEN(buf[0]);
 
 	if (len < 1 + payload_len)
 		return ARM_SPE_NEED_MORE_BYTES;
@@ -136,8 +134,6 @@ static int arm_spe_get_timestamp(const unsigned char *buf, size_t len,
 static int arm_spe_get_events(const unsigned char *buf, size_t len,
 			      struct arm_spe_pkt *packet)
 {
-	int ret = arm_spe_get_payload(buf, len, packet);
-
 	packet->type = ARM_SPE_EVENTS;
 
 	/* we use index to identify Events with a less number of
@@ -145,9 +141,9 @@ static int arm_spe_get_events(const unsigned char *buf, size_t len,
 	 * LLC-REFILL, and REMOTE-ACCESS events are identified if
 	 * index > 1.
 	 */
-	packet->index = ret - 1;
+	packet->index = PAYLOAD_LEN(buf[0]);
 
-	return ret;
+	return arm_spe_get_payload(buf, len, packet);
 }
 
 static int arm_spe_get_data_source(const unsigned char *buf, size_t len,
diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h
index 4c870521b8eb..aca919159cad 100644
--- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h
+++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h
@@ -36,6 +36,9 @@ struct arm_spe_pkt {
 	uint64_t		payload;
 };
 
+#define SPE_HEADER_SZ_SHIFT		(4)
+#define SPE_HEADER_SZ_MASK		(0x30)
+
 #define SPE_ADDR_PKT_HDR_INDEX_INS		(0x0)
 #define SPE_ADDR_PKT_HDR_INDEX_BRANCH		(0x1)
 #define SPE_ADDR_PKT_HDR_INDEX_DATA_VIRT	(0x2)
-- 
2.17.1