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=-10.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 AAAD0C54E8D for ; Mon, 11 May 2020 20:43:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7CFC32075E for ; Mon, 11 May 2020 20:43:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589229782; bh=+CCI+6XYW4jv1KuUrAbjuCuJOFWZCYBS4Rh74IvMaIg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Wku78RDqC8MsYTULPP38J2tD6UJVYNt9wejo1qs9RqeCIOSoxq18CU6JFmkBMPsZG YrblEvqDsumpFB5OrXvJP/SjZkKbN0YI2HRm4IgwGowFtF6Ge/zL+t71jGjtkLVFgG O1RCsLqETYOi2kWuacck9Ms2FLAdPm45wpeboEjA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731911AbgEKUnB (ORCPT ); Mon, 11 May 2020 16:43:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:54834 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731896AbgEKUnA (ORCPT ); Mon, 11 May 2020 16:43:00 -0400 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 63BC320A8B; Mon, 11 May 2020 20:42:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589229779; bh=+CCI+6XYW4jv1KuUrAbjuCuJOFWZCYBS4Rh74IvMaIg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pz19izpQ+98KiaT366Vmxvq72eia2cLiZRWxUSDMW99mQDAAlY+HHC1VarpNKfylO qurYlWz4bul5382PKI+fH/BfllETbIDkQDYEvFBK3vNN+bfI9SdAQMNsLGc5FLgZDF MIUYmvdiHhLhmFs7burG0C0tbc6yEaa9KODCSZr4= From: Will Deacon To: linux-kernel@vger.kernel.org Cc: elver@google.com, tglx@linutronix.de, paulmck@kernel.org, mingo@kernel.org, peterz@infradead.org, will@kernel.org Subject: [PATCH v5 16/18] kcsan: Rework data_race() so that it can be used by READ_ONCE() Date: Mon, 11 May 2020 21:41:48 +0100 Message-Id: <20200511204150.27858-17-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200511204150.27858-1-will@kernel.org> References: <20200511204150.27858-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rework the data_race() macro so that it: - Accepts expressions which evaluate to a 'const' type - Attempts to discard volatile qualifiers from scalar types, avoiding pointless stack spills - Uses __kcsan_{disable,enable}_current(), allowing its use from code that is built independently from the kernel, such as the vDSO This will allow for its use by {READ,WRITE}_ONCE() in a subsequent patch. At the same time, fix-up some weird whitespace issues. Cc: Marco Elver Signed-off-by: Will Deacon --- include/linux/compiler.h | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 0caced170a8a..f2a64195ee8e 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -314,14 +314,15 @@ unsigned long read_word_at_a_time(const void *addr) * This macro *does not* affect normal code generation, but is a hint * to tooling that data races here are to be ignored. */ -#define data_race(expr) \ - ({ \ - typeof(({ expr; })) __val; \ - kcsan_disable_current(); \ - __val = ({ expr; }); \ - kcsan_enable_current(); \ - __val; \ - }) +#define data_race(expr) \ +({ \ + __kcsan_disable_current(); \ + ({ \ + __unqual_scalar_typeof(({ expr; })) __v = ({ expr; }); \ + __kcsan_enable_current(); \ + __v; \ + }); \ +}) #else #endif /* __KERNEL__ */ -- 2.26.2.645.ge9eca65c58-goog