From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guo Ren Subject: Re: [PATCH V9 21/21] csky: support dword access for get_user_size() Date: Thu, 18 Oct 2018 11:41:18 +0800 Message-ID: <20181018034117.GD15088@guoren-Inspiron-7460> References: <4bc11ff0cff5960892a464189605f9bc808383fc.1539655732.git.ren_guo@c-sky.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Arnd Bergmann Cc: Andrew Morton , Daniel Lezcano , David Miller , gregkh , Christoph Hellwig , Marc Zyngier , Mark Rutland , Peter Zijlstra , Rob Herring , Thomas Gleixner , Linux Kernel Mailing List , linux-arch , DTML , Rob Herring , c-sky_gcc_upstream@c-sky.com List-Id: linux-arch.vger.kernel.org On Wed, Oct 17, 2018 at 05:44:17PM +0200, Arnd Bergmann wrote: > On Tue, Oct 16, 2018 at 5:33 AM Guo Ren wrote: > > > > Support dword access for get_user_size and redesign put_user_size with > > the same style of get_user_size. It's Ok to use xxx_user_asm_common for > > all size of variable with ldb, ldh, ldw, ld.d > > > > ld.d rx, (addr, 0) could "rx <= addr" "and r(x+1) <= addr+4" and this also > > follow abiv2 gcc ABI for dword access. > > Are you sure this is correct for this? > > static inline u32 get_64_to_32(__u64 __user *p) > { > u32 ret; > get_user(ret, p); > return ret; > } > > If I read __get_user_asm_common() right, the ld.d would overwrite > two registers, but the caller only expects one, so it clobbers one > that might be in use. Ah... BUG! I only consider the get_user(u64, u64 *) :P Change to: case 8: \ __get_user_asm_dword((x), ptr, "ld.d", retval); \ break; #define __get_user_asm_dword(x, ptr, err) \ do { \ u64 tmp; \ __get_user_asm_common(tmp, ptr, "ld.d", err); \ x = typeof(x) tmp; \ } while(0) #define __put_user_asm_dword(x, ptr, err) \ do { \ u64 tmp = (u64) x; \ __put_user_asm_common(tmp, ptr, "st.d", err); \ } while(0) Hmm? Best Regards Guo Ren From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp2200-217.mail.aliyun.com ([121.197.200.217]:40939 "EHLO smtp2200-217.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727297AbeJRLkt (ORCPT ); Thu, 18 Oct 2018 07:40:49 -0400 Date: Thu, 18 Oct 2018 11:41:18 +0800 From: Guo Ren Subject: Re: [PATCH V9 21/21] csky: support dword access for get_user_size() Message-ID: <20181018034117.GD15088@guoren-Inspiron-7460> References: <4bc11ff0cff5960892a464189605f9bc808383fc.1539655732.git.ren_guo@c-sky.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Arnd Bergmann Cc: Andrew Morton , Daniel Lezcano , David Miller , gregkh , Christoph Hellwig , Marc Zyngier , Mark Rutland , Peter Zijlstra , Rob Herring , Thomas Gleixner , Linux Kernel Mailing List , linux-arch , DTML , Rob Herring , c-sky_gcc_upstream@c-sky.com Message-ID: <20181018034118.RyCcO5nr34pMXY75PHZIvKfB2wRnmnkSWNv-eUWFahc@z> On Wed, Oct 17, 2018 at 05:44:17PM +0200, Arnd Bergmann wrote: > On Tue, Oct 16, 2018 at 5:33 AM Guo Ren wrote: > > > > Support dword access for get_user_size and redesign put_user_size with > > the same style of get_user_size. It's Ok to use xxx_user_asm_common for > > all size of variable with ldb, ldh, ldw, ld.d > > > > ld.d rx, (addr, 0) could "rx <= addr" "and r(x+1) <= addr+4" and this also > > follow abiv2 gcc ABI for dword access. > > Are you sure this is correct for this? > > static inline u32 get_64_to_32(__u64 __user *p) > { > u32 ret; > get_user(ret, p); > return ret; > } > > If I read __get_user_asm_common() right, the ld.d would overwrite > two registers, but the caller only expects one, so it clobbers one > that might be in use. Ah... BUG! I only consider the get_user(u64, u64 *) :P Change to: case 8: \ __get_user_asm_dword((x), ptr, "ld.d", retval); \ break; #define __get_user_asm_dword(x, ptr, err) \ do { \ u64 tmp; \ __get_user_asm_common(tmp, ptr, "ld.d", err); \ x = typeof(x) tmp; \ } while(0) #define __put_user_asm_dword(x, ptr, err) \ do { \ u64 tmp = (u64) x; \ __put_user_asm_common(tmp, ptr, "st.d", err); \ } while(0) Hmm? Best Regards Guo Ren