Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751437AbaLOLXW (ORCPT ); Mon, 15 Dec 2014 06:23:22 -0500 Received: from gw-1.arm.linux.org.uk ([78.32.30.217]:59447 "EHLO pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750782AbaLOLXT (ORCPT ); Mon, 15 Dec 2014 06:23:19 -0500 Date: Mon, 15 Dec 2014 11:23:11 +0000 From: Russell King - ARM Linux To: Will Deacon Cc: "Michael S. Tsirkin" , "linux-arch@vger.kernel.org" , Arnd Bergmann , Catalin Marinas , "linux-kernel@vger.kernel.org" , Christopher Covington , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH 03/18] arm64/uaccess: fix sparse errors Message-ID: <20141215112310.GG11285@n2100.arm.linux.org.uk> References: <1418575877-21488-1-git-send-email-mst@redhat.com> <1418575877-21488-4-git-send-email-mst@redhat.com> <20141215111716.GG20738@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141215111716.GG20738@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 15, 2014 at 11:17:16AM +0000, Will Deacon wrote: > On Sun, Dec 14, 2014 at 04:52:09PM +0000, Michael S. Tsirkin wrote: > > virtio wants to read bitwise types from userspace using get_user. At the > > moment this triggers sparse errors, since the value is passed through an > > integer. > > > > Fix that up using __force. > > > > Signed-off-by: Michael S. Tsirkin > > --- > > arch/arm64/include/asm/uaccess.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h > > index 3bf8f4e..8d66bcf 100644 > > --- a/arch/arm64/include/asm/uaccess.h > > +++ b/arch/arm64/include/asm/uaccess.h > > @@ -147,7 +147,7 @@ do { \ > > default: \ > > BUILD_BUG(); \ > > } \ > > - (x) = (__typeof__(*(ptr)))__gu_val; \ > > + (x) = (__force __typeof__(*(ptr)))__gu_val; \ > > } while (0) > > > > #define __get_user(x, ptr) \ > > Acked-by: Will Deacon This also means you can do stuff like: u32 *p; __le32 v; err = get_user(p, v); which is not right. Both the dereferenced pointer type and the destination type should be compatible, and if one is a bitwise type but the other isn't, that seems like a valid case to warn. I don't see any use of get_user() in drivers/virtio in mainline, so I can't check further. -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/