From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932681AbcKNCX0 (ORCPT ); Sun, 13 Nov 2016 21:23:26 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:47094 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754085AbcKNCXW (ORCPT ); Sun, 13 Nov 2016 21:23:22 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, linux-metag@vger.kernel.org, "James Hogan" Date: Mon, 14 Nov 2016 00:14:20 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 146/346] metag: Fix __cmpxchg_u32 asm constraint for CMP In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.39-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: James Hogan commit 6154c187b97ee7513046bb4eb317a89f738f13ef upstream. The LNKGET based atomic sequence in __cmpxchg_u32 has slightly incorrect constraints for the return value which under certain circumstances can allow an address unit register to be used as the first operand of a CMP instruction. This isn't a valid instruction however as the encodings only allow a data unit to be specified. This would result in an assembler error like the following: Error: failed to assemble instruction: "CMP A0.2,D0Ar6" Fix by changing the constraint from "=&da" (assigned, early clobbered, data or address unit register) to "=&d" (data unit register only). The constraint for the second operand, "bd" (an op2 register where op1 is a data unit register and the instruction supports O2R) is already correct assuming the first operand is a data unit register. Other cases of CMP in inline asm have had their constraints checked, and appear to all be fine. Fixes: 6006c0d8ce94 ("metag: Atomics, locks and bitops") Signed-off-by: James Hogan Cc: linux-metag@vger.kernel.org Signed-off-by: Ben Hutchings --- arch/metag/include/asm/cmpxchg_lnkget.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/metag/include/asm/cmpxchg_lnkget.h +++ b/arch/metag/include/asm/cmpxchg_lnkget.h @@ -73,7 +73,7 @@ static inline unsigned long __cmpxchg_u3 " DCACHE [%2], %0\n" #endif "2:\n" - : "=&d" (temp), "=&da" (retval) + : "=&d" (temp), "=&d" (retval) : "da" (m), "bd" (old), "da" (new) : "cc" );