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Date: Thu, 18 Aug 2016 15:54:54 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, James Hogan <james.hogan@...tec.com>, linux-metag@...r.kernel.org Subject: [PATCH 3.14 32/46] metag: Fix __cmpxchg_u32 asm constraint for CMP 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: James Hogan <james.hogan@...tec.com> 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 <james.hogan@...tec.com> Cc: linux-metag@...r.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- 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" );
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