From patchwork Tue Jul 20 02:21:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunsheng Lin X-Patchwork-Id: 482042 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 794C9C07E95 for ; Tue, 20 Jul 2021 02:35:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 51B5861164 for ; Tue, 20 Jul 2021 02:35:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345012AbhGTByO (ORCPT ); Mon, 19 Jul 2021 21:54:14 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:12229 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344641AbhGTBmB (ORCPT ); Mon, 19 Jul 2021 21:42:01 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.54]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4GTMm14W4yz1CLM4; Tue, 20 Jul 2021 10:16:49 +0800 (CST) Received: from dggpemm500005.china.huawei.com (7.185.36.74) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 20 Jul 2021 10:22:34 +0800 Received: from localhost.localdomain (10.69.192.56) by dggpemm500005.china.huawei.com (7.185.36.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 20 Jul 2021 10:22:34 +0800 From: Yunsheng Lin To: , , , CC: , , , , , , , , , , , , Subject: [PATCH v2 3/4] tools headers UAPI: add cpu_relax() implementation for x86 and arm64 Date: Tue, 20 Jul 2021 10:21:48 +0800 Message-ID: <1626747709-34013-4-git-send-email-linyunsheng@huawei.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1626747709-34013-1-git-send-email-linyunsheng@huawei.com> References: <1626747709-34013-1-git-send-email-linyunsheng@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.69.192.56] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500005.china.huawei.com (7.185.36.74) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org As x86 and arm64 is the two available systems that I can build and test the cpu_relax() implementation, so only add cpu_relax() implementation for x86 and arm64, other arches can be added easily when needed. Signed-off-by: Yunsheng Lin --- tools/include/asm/processor.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 tools/include/asm/processor.h diff --git a/tools/include/asm/processor.h b/tools/include/asm/processor.h new file mode 100644 index 0000000..f9b3902 --- /dev/null +++ b/tools/include/asm/processor.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef __TOOLS_LINUX_ASM_PROCESSOR_H +#define __TOOLS_LINUX_ASM_PROCESSOR_H + +#if defined(__i386__) || defined(__x86_64__) +/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */ +static __always_inline void rep_nop(void) +{ + asm volatile("rep; nop" ::: "memory"); +} + +static __always_inline void cpu_relax(void) +{ + rep_nop(); +} +#elif defined(__aarch64__) +static inline void cpu_relax(void) +{ + asm volatile("yield" ::: "memory"); +} +#else +#error "Architecture not supported" +#endif + +#endif