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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B19EC25B0C for ; Tue, 9 Aug 2022 13:54:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244035AbiHINyC (ORCPT ); Tue, 9 Aug 2022 09:54:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241782AbiHINx4 (ORCPT ); Tue, 9 Aug 2022 09:53:56 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6FB3963F7 for ; Tue, 9 Aug 2022 06:53:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0E38D6119C for ; Tue, 9 Aug 2022 13:53:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 694BFC433D7; Tue, 9 Aug 2022 13:53:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660053234; bh=ZPOL6VRGLr3cwR50wMtN7UPDd2SZQTKj6fGYSXQQiJ4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=HDzwep5/+dlBWSHaIVIJeEr4UClYY2zEOvjtpBzHrcKY50bvtY03oX3f20S6k/LzB m6ZkO0Cz2XiNPbP/Q0Q//IQ9iiWRr7uinV5uyTtcBfDWXC4dcYjhMBepR2iIUMUyRK jxrgu7pYfLES2dFqR9sWjyiBq+ESgn3xnaxJQTuJGVNWE3nWE4dzb22tJ6AIYUTizr pGmmXCvKRdb7RDEQCkcfiMjjTf1JAgE16VLbMIk5EOVSspUxAgDg3FtmyxQDTggi9b G5vEB8SY7lmVPdkmMQ9yEIPrrdyZ5votZZfpcKo3F3QSCYTswFad7MysVTvdW+d8Ke H0FttX0EwIDDQ== Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1oLPg8-001vSO-5u; Tue, 09 Aug 2022 14:53:52 +0100 Date: Tue, 09 Aug 2022 14:53:51 +0100 Message-ID: <87wnbhv7yo.wl-maz@kernel.org> From: Marc Zyngier To: Yang Yingliang Cc: , , , , , , Subject: Re: [PATCH v2] KVM: arm64: fix compile error because of shift overflow In-Reply-To: <20220809135127.480285-1-yangyingliang@huawei.com> References: <20220809135127.480285-1-yangyingliang@huawei.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: yangyingliang@huawei.com, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 09 Aug 2022 14:51:27 +0100, Yang Yingliang wrote: >=20 > Using GENMASK() to generate the masks of device type and device id, it ma= kes > code unambiguous, also it can fix the following fix compile error because= of > shift overflow when using low verison gcc(mine version is 7.5): >=20 > In function =E2=80=98kvm_vm_ioctl_set_device_addr.isra.38=E2=80=99, > inlined from =E2=80=98kvm_arch_vm_ioctl=E2=80=99 at arch/arm64/kvm/ar= m.c:1454:10: > ././include/linux/compiler_types.h:354:38: error: call to =E2=80=98__comp= iletime_assert_599=E2=80=99 \ > declared with attribute error: FIELD_GET: mask is not constant > _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) >=20 > Fixes: 9f968c9266aa ("KVM: arm64: vgic-v2: Add helper for legacy dist/cpu= if base address setting") > Signed-off-by: Yang Yingliang > --- > v2: > Using GENMASK() to generate the masks. > --- > arch/arm64/include/uapi/asm/kvm.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) >=20 > diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/= asm/kvm.h > index 3bb134355874..5e7dfaf76ec1 100644 > --- a/arch/arm64/include/uapi/asm/kvm.h > +++ b/arch/arm64/include/uapi/asm/kvm.h > @@ -75,9 +75,9 @@ struct kvm_regs { > =20 > /* KVM_ARM_SET_DEVICE_ADDR ioctl id encoding */ > #define KVM_ARM_DEVICE_TYPE_SHIFT 0 > -#define KVM_ARM_DEVICE_TYPE_MASK (0xffff << KVM_ARM_DEVICE_TYPE_SHIFT) > +#define KVM_ARM_DEVICE_TYPE_MASK GENMASK(15, KVM_ARM_DEVICE_TYPE_SHIFT) > #define KVM_ARM_DEVICE_ID_SHIFT 16 > -#define KVM_ARM_DEVICE_ID_MASK (0xffff << KVM_ARM_DEVICE_ID_SHIFT) > +#define KVM_ARM_DEVICE_ID_MASK GENMASK(31, KVM_ARM_DEVICE_ID_SHIFT) > =20 > /* Supported device IDs */ > #define KVM_ARM_DEVICE_VGIC_V2 0 This is marginally better, but what I was expecting is something like: #define KVM_ARM_DEVICE_ID_MASK GENMASK(KVM_ARM_DEVICE_ID_SHIFT + 15, \ KVM_ARM_DEVICE_ID_SHIFT) which I find a bit more readable. Thanks, M. --=20 Without deviation from the norm, progress is not possible.