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=-15.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 7F205C47083 for ; Wed, 2 Jun 2021 10:51:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5579A61361 for ; Wed, 2 Jun 2021 10:51:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232123AbhFBKxK (ORCPT ); Wed, 2 Jun 2021 06:53:10 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:6139 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230124AbhFBKvy (ORCPT ); Wed, 2 Jun 2021 06:51:54 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Fw5MG3jqzzYpXh; Wed, 2 Jun 2021 18:47:22 +0800 (CST) Received: from dggema757-chm.china.huawei.com (10.1.198.199) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Wed, 2 Jun 2021 18:50:03 +0800 Received: from [127.0.0.1] (10.69.38.203) by dggema757-chm.china.huawei.com (10.1.198.199) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Wed, 2 Jun 2021 18:50:03 +0800 Subject: Re: [PATCH v2 1/9] perf: Add EVENT_ATTR_ID to simplify event attributes To: Will Deacon CC: Linuxarm , , , Peter Zijlstra , "Ingo Molnar" , Arnaldo Carvalho de Melo , "Mark Rutland" , Alexander Shishkin References: <1621417919-6632-1-git-send-email-liuqi115@huawei.com> <1621417919-6632-2-git-send-email-liuqi115@huawei.com> <20210601131020.GD28025@willie-the-truck> <30abdbec-3174-1f8a-47d4-63a4de3b1e47@huawei.com> <20210602094922.GA30503@willie-the-truck> From: "liuqi (BA)" Message-ID: <9b764f1c-3c69-b825-5d5e-640d26be79e4@huawei.com> Date: Wed, 2 Jun 2021 18:49:57 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20210602094922.GA30503@willie-the-truck> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Originating-IP: [10.69.38.203] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggema757-chm.china.huawei.com (10.1.198.199) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Will, On 2021/6/2 17:49, Will Deacon wrote: > On Wed, Jun 02, 2021 at 04:45:23PM +0800, liuqi (BA) wrote: >> >> Hi Will, >> >> Thanks for reviewing this patch. >> >> On 2021/6/1 21:10, Will Deacon wrote: >>> On Wed, May 19, 2021 at 05:51:51PM +0800, Qi Liu wrote: >>>> Similar EVENT_ATTR macros are defined in many PMU drivers, >>>> like HiSilicon PMU driver, Arm PMU driver, Arm SMMU PMU >>>> driver. So Add a generic macro to simplify code. >>>> >>>> Cc: Peter Zijlstra >>>> Cc: Ingo Molnar >>>> Cc: Arnaldo Carvalho de Melo >>>> Cc: Mark Rutland >>>> Cc: Alexander Shishkin >>>> Signed-off-by: Qi Liu >>>> --- >>>> include/linux/perf_event.h | 6 ++++++ >>>> kernel/events/core.c | 2 ++ >>>> 2 files changed, 8 insertions(+) >>>> >>>> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h >>>> index f5a6a2f..d0aa74e 100644 >>>> --- a/include/linux/perf_event.h >>>> +++ b/include/linux/perf_event.h >>>> @@ -1576,6 +1576,12 @@ static struct perf_pmu_events_attr _var = { \ >>>> .event_str = _str, \ >>>> }; >>>> +#define PMU_EVENT_ATTR_ID(_name, _id) \ >>>> + (&((struct perf_pmu_events_attr[]) { \ >>>> + { .attr = __ATTR(_name, 0444, perf_event_sysfs_show, NULL), \ >>>> + .id = _id, } \ >>>> + })[0].attr.attr) >>>> + >>>> #define PMU_FORMAT_ATTR(_name, _format) \ >>>> static ssize_t \ >>>> _name##_show(struct device *dev, \ >>>> diff --git a/kernel/events/core.c b/kernel/events/core.c >>>> index 0ac818b..330d9cc 100644 >>>> --- a/kernel/events/core.c >>>> +++ b/kernel/events/core.c >>>> @@ -13295,6 +13295,8 @@ ssize_t perf_event_sysfs_show(struct device *dev, struct device_attribute *attr, >>>> if (pmu_attr->event_str) >>>> return sprintf(page, "%s\n", pmu_attr->event_str); >>>> + else >>>> + return sprintf(page, "config=%#llx\n", pmu_attr->id); >>> >>> I think it's a really bad idea to hardcode this here. For example, I think >>> this patch series breaks user ABI for the SMMU PMU which used to print: >>> >>> "event=0x%02llx\n" >>> >>> and by the looks of it many of the other conversions are unsound too. >>> >> Got it, so I'll use pmu_attr->event_str here, for example, >> SMMU_EVENT_ATTR(cycles, "event=0x00") > > You could, but honestly I don't really see this being any better than the > current code. The advantage of using "event=0x%02llx\n" is that things are > consistent by construction and therefore userspace can parse the information > easily. We lose that if we just hardcode the string and it's error-prone to > extend. > > Will Got it, thanks. So how about adding a common macro like this: #define PMU_EVENT_ATTR_ID(_name,_func, _id) \ (&((struct perf_pmu_events_attr[]) { \ { .attr = __ATTR(_name, 0444, _func, NULL), \ .id = _id, } \ })[0].attr.attr) Drivers could define thir private macro, like SMMU_PMU_EVENT_ATTR, and use their private event_show() functions if they need, or use the common function perf_event_sysfs_show(). Thanks, Qi > . >