From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [PATCH 4.7 143/186] metag: Fix __cmpxchg_u32 asm constraint for CMP Date: Thu, 18 Aug 2016 15:59:20 +0200 Message-ID: <20160818135938.361466669@linuxfoundation.org> References: <20160818135932.219369981@linuxfoundation.org> Mime-Version: 1.0 Return-path: In-Reply-To: <20160818135932.219369981@linuxfoundation.org> Sender: stable-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, James Hogan , linux-metag@vger.kernel.org 4.7-stable 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: Greg Kroah-Hartman --- 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" );