From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32D98C4363A for ; Thu, 8 Oct 2020 13:45:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D797A21D80 for ; Thu, 8 Oct 2020 13:45:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730394AbgJHNpy (ORCPT ); Thu, 8 Oct 2020 09:45:54 -0400 Received: from foss.arm.com ([217.140.110.172]:58462 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730387AbgJHNpy (ORCPT ); Thu, 8 Oct 2020 09:45:54 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 59FB91529; Thu, 8 Oct 2020 06:45:53 -0700 (PDT) Received: from [192.168.2.22] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 65DDF3F70D; Thu, 8 Oct 2020 06:45:50 -0700 (PDT) From: =?UTF-8?Q?Andr=c3=a9_Przywara?= Subject: Re: [PATCH v2 03/14] perf arm-spe: Refactor payload length calculation To: Leo Yan , Arnaldo Carvalho de Melo , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Wei Li , James Clark , Dave Martin , linux-kernel@vger.kernel.org, Al Grant References: <20200929133917.9224-1-leo.yan@linaro.org> <20200929133917.9224-4-leo.yan@linaro.org> Organization: ARM Ltd. Message-ID: <995b40af-13b9-faef-fb3b-235f04289eb5@arm.com> Date: Thu, 8 Oct 2020 14:44:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200929133917.9224-4-leo.yan@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/09/2020 14:39, Leo Yan wrote: Hi Leo, > Defines macro for payload length calculation instead of static function. What is the reason for that? I thought the kernel's direction is more the other way: replacing macros with static functions ("Don't write CPP, write C")? Ideally the compiler would generate the same code. > 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 > --- > .../arm-spe-decoder/arm-spe-pkt-decoder.c | 26 ++++++++----------- > .../arm-spe-decoder/arm-spe-pkt-decoder.h | 4 +++ > 2 files changed, 15 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)) This change of the expression is good (although it should be 1U), but please keep it a function. The return type should be unsigned, I guess. The rest looks fine. Cheers, Andre > > 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..f2d0af39a58c 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 > @@ -9,6 +9,7 @@ > > #include > #include > +#include > > #define ARM_SPE_PKT_DESC_MAX 256 > > @@ -36,6 +37,9 @@ struct arm_spe_pkt { > uint64_t payload; > }; > > +#define SPE_HEADER_SZ_SHIFT (4) > +#define SPE_HEADER_SZ_MASK GENMASK_ULL(5, 4) > + > #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) >