From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753001Ab2KLT6f (ORCPT ); Mon, 12 Nov 2012 14:58:35 -0500 Received: from mail-vc0-f174.google.com ([209.85.220.174]:56536 "EHLO mail-vc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752055Ab2KLT6d (ORCPT ); Mon, 12 Nov 2012 14:58:33 -0500 MIME-Version: 1.0 In-Reply-To: <20121112192727.GB28341@n2100.arm.linux.org.uk> References: <1352495853-9790-1-git-send-email-rob.clark@linaro.org> <20121112192727.GB28341@n2100.arm.linux.org.uk> Date: Mon, 12 Nov 2012 13:58:32 -0600 X-Google-Sender-Auth: CXkNJnk_7ua9x0qB2bXWqj8Rbjk Message-ID: Subject: Re: [PATCH] ARM: add get_user() support for 8 byte types From: Rob Clark To: Russell King - ARM Linux Cc: linux-arm-kernel@lists.infradead.org, patches@linaro.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, dri-devel@lists.freedesktop.org, Arnd Bergmann Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 12, 2012 at 1:27 PM, Russell King - ARM Linux wrote: > On Fri, Nov 09, 2012 at 03:17:33PM -0600, Rob Clark wrote: >> From: Rob Clark >> >> A new atomic modeset/pageflip ioctl being developed in DRM requires >> get_user() to work for 64bit types (in addition to just put_user()). > > NAK. > > (I did write a better email explaining all the ins and outs of why this > won't work and why 64-bit get_user isn't possible, but my editor crapped > out and lost all that well written message; I don't fancy typing it all > out again.) > > Nevertheless, > int test_ptr(unsigned int **v, unsigned int **p) > { > return get_user(*v, p); > } > > produces a warning, and you can't get away from that if you stick 64-bit > support into get_user(). Actually, it seems like using 'register typeof(x) __r2 asm("r2");' does avoid that warning.. I don't know if that was the only argument against 64-bit get_user(). But it will at least be inconvenient that get_user() works for 64bit on x86 but not arm.. BR, -R > Sorry, 64-bit get_user() is a no-no. > > -- > To unsubscribe from this list: send the line "unsubscribe linux-omap" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html