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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 C9C88CA9ED0 for ; Fri, 1 Nov 2019 11:12:05 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A217020659 for ; Fri, 1 Nov 2019 11:12:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="pko4pNbL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A217020659 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=0BGzkgIz/QjpH97i6JM3YIsMFTDKazpugSAudzjsc9c=; b=pko4pNbLZm32vGopjyhbKWvEZ W/iCMG2FceZdrtug1s8XLogJ3ljL6InSQ/J3SlphA0rgYiCmWwjh2p/FONEM+Vvfv6iIxEILjN6E3 l6zk3PW/b1oh4aicgPH+iDXO0Z4qlnujGlHLO5efGwOeSyVnKjA0NW+XSsP4ZKWD+UEqmoK8tMECd 2p5yC3t1+f+mJvV4UsQmpOdbrWTYGFgdNGojMKkU3t8A+S/S+dysqh7PfRjptiZtpNLeBmtokrIFX Yp0XOhb9QxZO2mgfcCDNpRdMwEtn49O9K5Nc2GPZ/oXQEVjph+kxqplSOFqNyu6W/GDU8pKtqPSwH blbZuwerQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iQUqT-0008WU-Nt; Fri, 01 Nov 2019 11:11:57 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iQUqP-0008UT-Ma for linux-arm-kernel@lists.infradead.org; Fri, 01 Nov 2019 11:11:55 +0000 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 8150C46A; Fri, 1 Nov 2019 04:11:50 -0700 (PDT) Received: from [192.168.1.124] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C2D683F6C4; Fri, 1 Nov 2019 04:11:49 -0700 (PDT) Subject: Re: [PATCH] arm64: perf: Simplify the ARMv8 PMUv3 event attributes To: Will Deacon References: <1572407177-48229-1-git-send-email-zhangshaokun@hisilicon.com> <20191031160804.GA28325@willie-the-truck> <20191101085319.GA3508@blommer> <20191101103616.GA2392@willie-the-truck> <20191101105557.GC2392@willie-the-truck> From: Robin Murphy Message-ID: <7b1e730e-9083-75b9-f1bc-7d84c686c97c@arm.com> Date: Fri, 1 Nov 2019 11:11:49 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <20191101105557.GC2392@willie-the-truck> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191101_041153_823904_025FB50F X-CRM114-Status: GOOD ( 15.46 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Shaokun Zhang , linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2019-11-01 10:55 am, Will Deacon wrote: > On Fri, Nov 01, 2019 at 10:54:21AM +0000, Robin Murphy wrote: >> On 2019-11-01 10:36 am, Will Deacon wrote: >>> On Fri, Nov 01, 2019 at 08:53:19AM +0000, Mark Rutland wrote: >>>> On Thu, Oct 31, 2019 at 04:08:04PM +0000, Will Deacon wrote: >>>>> On Wed, Oct 30, 2019 at 11:46:17AM +0800, Shaokun Zhang wrote: >>>>>> For each PMU event, there is a ARMV8_EVENT_ATTR(xx, XX) and >>>>>> &armv8_event_attr_xx.attr.attr. Let's redefine the ARMV8_EVENT_ATTR >>>>>> to simplify the armv8_pmuv3_event_attrs. >>>>>> >>>>>> Cc: Will Deacon >>>>>> Cc: Mark Rutland >>>>>> Signed-off-by: Shaokun Zhang >>>>>> --- >>>>>> arch/arm64/kernel/perf_event.c | 189 ++++++++++++++--------------------------- >>>>>> 1 file changed, 65 insertions(+), 124 deletions(-) >>>>>> >>>>>> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c >>>>>> index a0b4f1bca491..d0f084939bcf 100644 >>>>>> --- a/arch/arm64/kernel/perf_event.c >>>>>> +++ b/arch/arm64/kernel/perf_event.c >>>>>> @@ -159,132 +159,73 @@ armv8pmu_events_sysfs_show(struct device *dev, >>>>>> } >>>>> >>>>> [...] >>>>> >>>>>> + (&((struct perf_pmu_events_attr[]) { \ >>>>>> + { .attr = __ATTR(name, 0444, armv8pmu_events_sysfs_show, NULL), \ >>>>>> + .id = config, } \ >>>>>> + })[0].attr.attr) >>>>> >>>>> I don't get the need for the array here. Why can't you do: >>>>> >>>>> (&((struct perf_pmu_events_attr) { >>>>> .attr = ..., >>>>> .id = ..., >>>>> }).attr.attr) >>>> >>>> You need want &(obj.attr.attr) rather than &(obj).attr.attr, i.e. >>>> >>>> #define ARMV8_EVENT_ATTR(name, config) \ >>>> (&((struct perf_pmu_events_attr) { \ >>>> .attr = __ATTR(name, 0444, armv8pmu_events_sysfs_show, NULL), \ >>>> .id = config, \ >>>> }.attr.attr)) >>>> ... which compiles for me. >>> >>> Weird, the following compiles fine for me with both GCC and clang: >>> >>> #define ARMV8_EVENT_ATTR(name, config) \ >>> (&((struct perf_pmu_events_attr) { \ >>> .attr = __ATTR(name, 0444, armv8pmu_events_sysfs_show, NULL), \ >>> .id = config, \ >>> }).attr.attr) >> >> You know that the expressions are equivalent because unary "&" has lower >> precedence than ".", right? ;) > > Right, which is why it's weird that Shaokun claims that the version I posted > doesn't compile. I assume it didn't build for Mark either, hence his extra > brackets. Because different compilers have different ideas of whether "obj" is a valid thing to dereference at all, regardless of where you put parentheses. From what I remember, the array trick was the only way to convince older GCCs to treat the floating struct initialiser as an actual object definition. I guess newer versions are a bit more lenient. Robin. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel