From patchwork Fri Mar 30 15:58:13 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sinan Kaya X-Patchwork-Id: 10318089 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 98FF06055B for ; Fri, 30 Mar 2018 15:58:44 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 884E42A5A1 for ; Fri, 30 Mar 2018 15:58:44 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7C6A62A5A5; Fri, 30 Mar 2018 15:58:44 +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 218A72A5A1 for ; Fri, 30 Mar 2018 15:58:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751968AbeC3P6b (ORCPT ); Fri, 30 Mar 2018 11:58:31 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:57464 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751264AbeC3P6V (ORCPT ); Fri, 30 Mar 2018 11:58:21 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 15C7960588; Fri, 30 Mar 2018 15:58:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1522425501; bh=QZbzmzB+wngm0aJQ8lOWK+iJYyejFtpxDn5Ruh/0EeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LGlyNs+XfmB9ADhAXJhUti9wC4sm0BFHhKg7DYysNTGU4xQdRV5q5BmKGZe++ZyCJ oEeDOcQuIFvaDNCZXhe5chpwJiLjJrq/dt/+hXnqPJR9jzJZImWWfTU4UCKdYmhfQ5 XZNqnEcAktdQGDAIqg/oEm9c8Ig0VYzuvidkhMtw= 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 9FEE360817; Fri, 30 Mar 2018 15:58:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1522425500; bh=QZbzmzB+wngm0aJQ8lOWK+iJYyejFtpxDn5Ruh/0EeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S4HBD+wwBseNc77kgjhxfzDkWNMQGHu6jn/y+og0IgVOaffXxvdd67PdsI019Lcib trDcFGLhhuab3P5pne6bQKNXIRzP4g1Gg5cmBgFdeSl3sP8byMAQ48bhMoV3hTh1ok mmRL9Omtdcjvc0F9apBU9lZ9Ea2prMF8Ngkdkm00= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 9FEE360817 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 v2 2/2] io: prevent compiler reordering on the default readX() implementation Date: Fri, 30 Mar 2018 11:58:13 -0400 Message-Id: <1522425494-2916-2-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1522425494-2916-1-git-send-email-okaya@codeaurora.org> References: <1522425494-2916-1-git-send-email-okaya@codeaurora.org> 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 readX() to __raw_readX() is wrong. readX() has stronger ordering semantics. Compiler is allowed to reorder __raw_readX(). In the abscence of a read barrier or when using a strongly ordered architecture, readX() 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 | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h index e8c2078..2554f15 100644 --- a/include/asm-generic/io.h +++ b/include/asm-generic/io.h @@ -110,7 +110,12 @@ static inline void __raw_writeq(u64 value, volatile void __iomem *addr) #define readb readb static inline u8 readb(const volatile void __iomem *addr) { - return __raw_readb(addr); + u8 val; + + val = __raw_readb(addr); + barrier(); + + return val; } #endif @@ -118,7 +123,12 @@ static inline u8 readb(const volatile void __iomem *addr) #define readw readw static inline u16 readw(const volatile void __iomem *addr) { - return __le16_to_cpu(__raw_readw(addr)); + u16 val; + + val = __le16_to_cpu(__raw_readw(addr)); + barrier(); + + return val; } #endif @@ -126,7 +136,12 @@ static inline u16 readw(const volatile void __iomem *addr) #define readl readl static inline u32 readl(const volatile void __iomem *addr) { - return __le32_to_cpu(__raw_readl(addr)); + u32 val; + + val = __le32_to_cpu(__raw_readl(addr)); + barrier(); + + return val; } #endif @@ -135,7 +150,12 @@ static inline u32 readl(const volatile void __iomem *addr) #define readq readq static inline u64 readq(const volatile void __iomem *addr) { - return __le64_to_cpu(__raw_readq(addr)); + u64 val; + + val = __le64_to_cpu(__raw_readq(addr)); + barrier(); + + return val; } #endif #endif /* CONFIG_64BIT */