From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:42742 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729280AbeKVFrQ (ORCPT ); Thu, 22 Nov 2018 00:47:16 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Rutland , Russell King , "David A. Long" Subject: [PATCH 4.9 57/59] ARM: use __inttype() in get_user() Date: Wed, 21 Nov 2018 20:07:12 +0100 Message-Id: <20181121183510.556421815@linuxfoundation.org> In-Reply-To: <20181121183508.262873520@linuxfoundation.org> References: <20181121183508.262873520@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Russell King Commit d09fbb327d670737ab40fd8bbb0765ae06b8b739 upstream. Borrow the x86 implementation of __inttype() to use in get_user() to select an integer type suitable to temporarily hold the result value. This is necessary to avoid propagating the volatile nature of the result argument, which can cause the following warning: lib/iov_iter.c:413:5: warning: optimization may eliminate reads and/or writes to register variables [-Wvolatile-register-var] Acked-by: Mark Rutland Signed-off-by: Russell King Signed-off-by: David A. Long Signed-off-by: Greg Kroah-Hartman --- arch/arm/include/asm/uaccess.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -115,6 +115,13 @@ static inline void set_fs(mm_segment_t f flag; }) /* + * This is a type: either unsigned long, if the argument fits into + * that type, or otherwise unsigned long long. + */ +#define __inttype(x) \ + __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) + +/* * Single-value transfer routines. They automatically use the right * size if we just have the right pointer type. Note that the functions * which read from user space (*get_*) need to take care not to leak @@ -183,7 +190,7 @@ extern int __get_user_64t_4(void *); ({ \ unsigned long __limit = current_thread_info()->addr_limit - 1; \ register const typeof(*(p)) __user *__p asm("r0") = (p);\ - register typeof(x) __r2 asm("r2"); \ + register __inttype(x) __r2 asm("r2"); \ register unsigned long __l asm("r1") = __limit; \ register int __e asm("r0"); \ unsigned int __ua_flags = uaccess_save_and_enable(); \