Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261790AbVDVAbK (ORCPT ); Thu, 21 Apr 2005 20:31:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261897AbVDVAav (ORCPT ); Thu, 21 Apr 2005 20:30:51 -0400 Received: from quark.didntduck.org ([69.55.226.66]:43999 "EHLO quark.didntduck.org") by vger.kernel.org with ESMTP id S261790AbVDVA17 (ORCPT ); Thu, 21 Apr 2005 20:27:59 -0400 Message-ID: <42684603.5050500@didntduck.org> Date: Thu, 21 Apr 2005 20:32:03 -0400 From: Brian Gerst User-Agent: Mozilla Thunderbird 1.0.2-1 (X11/20050323) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Alexander Nyberg CC: ak@suse.de, linux-kernel@vger.kernel.org, akpm@osdl.org, nicolas@boichat.ch Subject: Re: x86_64: Bug in new out of line put_user() References: <1114038609.500.2.camel@localhost.localdomain> In-Reply-To: <1114038609.500.2.camel@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2517 Lines: 100 Alexander Nyberg wrote: > The new out of line put_user() assembly on x86_64 changes %rcx without > telling GCC about it causing things like: > > http://bugme.osdl.org/show_bug.cgi?id=4515 > > See to it that %rcx is not changed (made it consistent with get_user()). > > > Signed-off-by: Alexander Nyberg > > Index: test/arch/x86_64/lib/getuser.S > =================================================================== > --- test.orig/arch/x86_64/lib/getuser.S 2005-04-20 23:55:35.000000000 +0200 > +++ test/arch/x86_64/lib/getuser.S 2005-04-21 00:54:16.000000000 +0200 > @@ -78,9 +78,9 @@ > __get_user_8: > GET_THREAD_INFO(%r8) > addq $7,%rcx > - jc bad_get_user > + jc 40f > cmpq threadinfo_addr_limit(%r8),%rcx > - jae bad_get_user > + jae 40f > subq $7,%rcx > 4: movq (%rcx),%rdx > xorl %eax,%eax > Index: test/arch/x86_64/lib/putuser.S > =================================================================== > --- test.orig/arch/x86_64/lib/putuser.S 2005-04-21 00:50:24.000000000 +0200 > +++ test/arch/x86_64/lib/putuser.S 2005-04-21 01:02:15.000000000 +0200 > @@ -46,36 +46,45 @@ > __put_user_2: > GET_THREAD_INFO(%r8) > addq $1,%rcx > - jc bad_put_user > + jc 20f > cmpq threadinfo_addr_limit(%r8),%rcx > - jae bad_put_user > -2: movw %dx,-1(%rcx) > + jae 20f > +2: decq %rcx > + movw %dx,(%rcx) > xorl %eax,%eax > ret > +20: decq %rcx > + jmp bad_put_user > > .p2align 4 > .globl __put_user_4 > __put_user_4: > GET_THREAD_INFO(%r8) > addq $3,%rcx > - jc bad_put_user > + jc 30f > cmpq threadinfo_addr_limit(%r8),%rcx > - jae bad_put_user > -3: movl %edx,-3(%rcx) > + jae 30f > +3: subq $3,%rcx > + movl %edx,(%rcx) > xorl %eax,%eax > ret > +30: subq $3,%rcx > + jmp bad_put_user > > .p2align 4 > .globl __put_user_8 > __put_user_8: > GET_THREAD_INFO(%r8) > addq $7,%rcx > - jc bad_put_user > + jc 40f > cmpq threadinfo_addr_limit(%r8),%rcx > - jae bad_put_user > -4: movq %rdx,-7(%rcx) > + jae 40f > +4: subq $7,%rcx > + movq %rdx,(%rcx) > xorl %eax,%eax > ret > +40: subq $7,%rcx > + jmp bad_put_user > > bad_put_user: > movq $(-EFAULT),%rax > > > - This patch has a serious bug. The 2, 3 and 4 labels must be on the mov instructions in order to catch faults. -- Brian Gerst - 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/