From patchwork Fri Mar 30 14:29:58 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sinan Kaya X-Patchwork-Id: 10317793 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7259F60212 for ; Fri, 30 Mar 2018 14:30:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 60FD42A599 for ; Fri, 30 Mar 2018 14:30:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 558DE2A5AB; Fri, 30 Mar 2018 14:30:23 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0221F2A599 for ; Fri, 30 Mar 2018 14:30:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751263AbeC3OaJ (ORCPT ); Fri, 30 Mar 2018 10:30:09 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:45276 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751223AbeC3OaI (ORCPT ); Fri, 30 Mar 2018 10:30:08 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 7C76660C65; Fri, 30 Mar 2018 14:30:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1522420207; bh=KrL3rspnoXhFNfc6kJLCf/rGowwlDCfFnZzVO6i2oyc=; h=From:To:Cc:Subject:Date:From; b=JLfAxOFVh58y4RbdPbWhr4rW6lV5rzOYaXtWbBSTrMIgfUbYfvzxcl+o8XDU67lKV caO1RDa0ZNygJ5DJdQPBfARIXE/zCNa9z9CRg3GHkHJQCvCTsMfrs97PU+MxVlgyw3 5ze2hz0L5+WlpE0hpK1/5G8/bUKhlVA/lUDB8wcc= Received: from drakthul.qualcomm.com (global_nat1_iad_fw.qualcomm.com [129.46.232.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: okaya@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 0AF0760ACA; Fri, 30 Mar 2018 14:30:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1522420206; bh=KrL3rspnoXhFNfc6kJLCf/rGowwlDCfFnZzVO6i2oyc=; h=From:To:Cc:Subject:Date:From; b=hspspHNSGj9r9X3Y2IfK7lLH3Z8IId4v2qQ5PB2r6kx7UROD/O7pbRt6ozC0XHCmC YDlnGE+9tTYK5E8gJFthykWGfsWfiU9kNoRmFpQlEoCdxQau04Eb/hS1+rYjqo9b1y oGyLx1g3SbdvhoEslnJHuI+4cb6Llc5tP8B3CiYU= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 0AF0760ACA Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=okaya@codeaurora.org From: Sinan Kaya To: arnd@arndb.de, timur@codeaurora.org, sulrich@codeaurora.org Cc: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] io: prevent compiler reordering on the default writeX() implementation Date: Fri, 30 Mar 2018 10:29:58 -0400 Message-Id: <1522420199-23548-1-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The default implementation of mapping writeX() to __raw_writeX() is wrong. writeX() has stronger ordering semantics. Compiler is allowed to reorder __raw_writeX(). In the abscence of a write barrier or when using a strongly ordered architecture, writeX() should at least have a compiler barrier in it to prevent commpiler from clobbering the execution order. Signed-off-by: Sinan Kaya --- include/asm-generic/io.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h index b4531e3..fbbf2bb 100644 --- a/include/asm-generic/io.h +++ b/include/asm-generic/io.h @@ -153,6 +153,7 @@ static inline void writeb(u8 value, volatile void __iomem *addr) static inline void writew(u16 value, volatile void __iomem *addr) { __raw_writew(cpu_to_le16(value), addr); + barrier(); } #endif @@ -161,6 +162,7 @@ static inline void writew(u16 value, volatile void __iomem *addr) static inline void writel(u32 value, volatile void __iomem *addr) { __raw_writel(__cpu_to_le32(value), addr); + barrier(); } #endif @@ -170,6 +172,7 @@ static inline void writel(u32 value, volatile void __iomem *addr) static inline void writeq(u64 value, volatile void __iomem *addr) { __raw_writeq(__cpu_to_le64(value), addr); + barrier(); } #endif #endif /* CONFIG_64BIT */