From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:36968 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729547AbeG0LdU (ORCPT ); Fri, 27 Jul 2018 07:33:20 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Bernd Edlinger , Arnd Bergmann Subject: [PATCH 4.4 23/23] ARM: fix put_user() for gcc-8 Date: Fri, 27 Jul 2018 12:09:24 +0200 Message-Id: <20180727100846.050436889@linuxfoundation.org> In-Reply-To: <20180727100845.054377089@linuxfoundation.org> References: <20180727100845.054377089@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Arnd Bergmann Building kernels before linux-4.7 with gcc-8 results in many build failures when gcc triggers a check that was meant to catch broken compilers: /tmp/ccCGMQmS.s:648: Error: .err encountered According to the discussion in the gcc bugzilla, a local "register asm()" variable is still supposed to be the correct way to force an inline assembly to use a particular register, but marking it 'const' lets the compiler do optimizations that break that, i.e the compiler is free to treat the variable as either 'const' or 'register' in that case. Upstream commit 9f73bd8bb445 ("ARM: uaccess: remove put_user() code duplication") fixed this problem in linux-4.8 as part of a larger change, but seems a little too big to be backported to 4.4. Let's take the simplest fix and change only the one broken line in the same way as newer kernels. Suggested-by: Bernd Edlinger Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85745 Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86673 Signed-off-by: Arnd Bergmann Signed-off-by: Greg Kroah-Hartman --- arch/arm/include/asm/uaccess.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -251,7 +251,7 @@ extern int __put_user_8(void *, unsigned ({ \ unsigned long __limit = current_thread_info()->addr_limit - 1; \ const typeof(*(p)) __user *__tmp_p = (p); \ - register const typeof(*(p)) __r2 asm("r2") = (x); \ + register typeof(*(p)) __r2 asm("r2") = (x); \ register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \ register unsigned long __l asm("r1") = __limit; \ register int __e asm("r0"); \