From patchwork Sat Dec 2 11:18:21 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jisheng Zhang X-Patchwork-Id: 172814 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:bcd1:0:b0:403:3b70:6f57 with SMTP id r17csp1709060vqy; Sat, 2 Dec 2023 03:31:27 -0800 (PST) X-Google-Smtp-Source: AGHT+IENf7MsTdUq4Z+ISmTbGsbI5nb2/IXDcIRckwoxz0re6SEmhiwWxr3glCAsAWjJX+WX4SaE X-Received: by 2002:a05:6a20:12c7:b0:187:4329:f06d with SMTP id v7-20020a056a2012c700b001874329f06dmr1132312pzg.31.1701516687336; Sat, 02 Dec 2023 03:31:27 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1701516687; cv=none; d=google.com; s=arc-20160816; b=PElM0Am+z9PihhrK2UvGPLKh58hSZp0vio3XBhfPwc7bJrSu5+Ql3mxNllni6BdQF1 YA67j/tlnzVz7TTqs+ouETw9YaTbRPTGNZTcAcxbJ32Tz9qf6zqOG4rkKEqJlpQyGvQz bMOLyAj/jxPV9jHnjm0R1JW5o4dsz/F4H79BFUyXJlkivmUrDNchqCyv1oFRj3laQGMK KEsH4sI9l3skwCksMFev1IEkLlI3vImU26PU5Bv5yAVjf4OAZsWs86yi9lkvv66kY26U 2ZYOjjbFEHb+wQGgJJZlueKkSeRAe/wwDk2u5rGVwPhFAIyqlhxKpePyv0b9rdam9JtY Gmyw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=VDxUpLDg0jA6jTJIZOk6kuPm7FANu37yPDuTw0kSlVI=; fh=srb/EijQIrMEdOeqn3qQX6qrsAGyqHAqeSFkl/qDdLM=; b=Jsy41EyOraaC4UXv2a+yyGY8HYuy3n1CaH1h9HJMkb7wTufK4YsJhT8BUsPSiGOlo2 mU5W6Wd5RH1jfQNSRjYlnjLm4Zct7VIfjF+Z24vmP/ZNrDWbKTvSGRj4jMH/SE1G9ozR rmi+rPD8Bt2PDQu1XmzP1wZVxq+USQkN3iPMY6I/0/BPmtHRta9/0e/8uSaKmvXyw7qX EFdJF+8iFlZ/8Y5T0GKYcODvsvSH7uLrfTK7dFa2Cs2/j7773sXWqQjfwsBuUyXJYo9p h884osH+oIk6tWQL8GKLrhHh//fMTAoGjQoXQ0TRHVdtI+LnPkakW6Tm1ozp/b0e5TIs i/hA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=ZeZCW75w; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from morse.vger.email (morse.vger.email. [23.128.96.31]) by mx.google.com with ESMTPS id q33-20020a635061000000b005bdbedcaf61si4871045pgl.674.2023.12.02.03.31.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 Dec 2023 03:31:27 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) client-ip=23.128.96.31; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=ZeZCW75w; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by morse.vger.email (Postfix) with ESMTP id EF241803DB00; Sat, 2 Dec 2023 03:31:24 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at morse.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232539AbjLBLap (ORCPT + 99 others); Sat, 2 Dec 2023 06:30:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232138AbjLBLan (ORCPT ); Sat, 2 Dec 2023 06:30:43 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1195E18C for ; Sat, 2 Dec 2023 03:30:50 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 854DEC433C9; Sat, 2 Dec 2023 11:30:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701516649; bh=oaq++MapooJ2EycnyO1+1SBXzHdLUChecLPa1P5lthc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZeZCW75wrX6ms+WZ1Q1JgUt/WzAHbFZf1HVXg2hrKN0kBjzw08Dy8KNefoQkj8QC9 CIbXEeuGws/75/j8IxDFJPY7WGCDnK4OnHFcKM+Jy+ijxoxxT0eRNeOCgzbKzZgh+d 8+ISGPYJgWL7hHCdil9LwMReV/TUPNhlFWZ4gkZKwKtmSNzfEDBSYPB0+ng5k+iV9g yckiS4b1k3jHwNDXGXit+F8HnicCnTOjKY3Nava6OZCxlh+d3jJ4iTookCYTDn7r1O ap+b3UJE72tLvB5dAFCaf1nxn0htHgn+LPssyVIvrUVOub1zx7vN2eRPm3GyWkb6gY K3uvO57syMwjw== From: Jisheng Zhang To: Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] riscv: introduce RISCV_EFFICIENT_UNALIGNED_ACCESS Date: Sat, 2 Dec 2023 19:18:21 +0800 Message-Id: <20231202111822.3569-2-jszhang@kernel.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20231202111822.3569-1-jszhang@kernel.org> References: <20231202111822.3569-1-jszhang@kernel.org> MIME-Version: 1.0 X-Spam-Status: No, score=-1.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Sat, 02 Dec 2023 03:31:25 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1784169561892697223 X-GMAIL-MSGID: 1784169561892697223 Some riscv implementations such as T-HEAD's C906, C908, C910 and C920 supports efficient unaligned access, for performance reason we want to enable HAVE_EFFICIENT_UNALIGNED_ACCESS on these platforms. To avoid performance regressions on other non efficient unaligned access platforms, HAVE_EFFICIENT_UNALIGNED_ACCESS can't be globaly selected. To solve this problem, runtime code patching based on the detected speed is a good solution. But that's not easy, it involves lots of work to modify vairous subsystems such as net, mm, lib and so on. This can be done step by step. Now let's introduce RISCV_EFFICIENT_UNALIGNED_ACCESS which depends on NONPORTABLE, if users know during config time that the kernel will be only run on those efficient unaligned access hw platforms, they can enable it. Obviously, generic unified kernel Image should enable it. Signed-off-by: Jisheng Zhang --- arch/riscv/Kconfig | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 7f8aa25457ba..0a76209e9b02 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -654,6 +654,18 @@ config RISCV_MISALIGNED load/store for both kernel and userspace. When disable, misaligned accesses will generate SIGBUS in userspace and panic in kernel. +config RISCV_EFFICIENT_UNALIGNED_ACCESS + bool "Use unaligned access for some functions" + depends on NONPORTABLE + select HAVE_EFFICIENT_UNALIGNED_ACCESS + default n + help + Say Y here if you want the kernel only run on hardware platforms which + support efficient unaligned access, then unaligned access will be used + in some functions for optimized performance. + + If unsure what to do here, say N. + endmenu # "Platform type" menu "Kernel features"