[PATCH] metag: Fix atomic_*_return inline asm constraints

[PATCH] metag: Fix atomic_*_return inline asm constraints

[James Hogan]

The argument i of atomic_*_return() operations is given to inline asm
with the "bd" constraint, which means "An Op2 register where Op1 is a
data unit register and the instruction supports O2R", however Op1 is
constrained by "da" which allows an address unit register to be used.

Fix the constraint to use "br", meaning "An Op2 register and the
instruction supports O2R", i.e. not requiring Op1 to be a data unit
register.

Fixes: d6dfe2509da9 ("locking,arch,metag: Fold atomic_ops")
Signed-off-by: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Cc: linux-metag-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
 arch/metag/include/asm/atomic_lnkget.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/metag/include/asm/atomic_lnkget.h b/arch/metag/include/asm/atomic_lnkget.h
index a62581815624..88fa25fae8bd 100644
--- a/arch/metag/include/asm/atomic_lnkget.h
+++ b/arch/metag/include/asm/atomic_lnkget.h
@@ -61,7 +61,7 @@ static inline int atomic_##op##_return(int i, atomic_t *v)		\
 		"	CMPT	%0, #HI(0x02000000)\n"			\
 		"	BNZ 1b\n"					\
 		: "=&d" (temp), "=&da" (result)				\
-		: "da" (&v->counter), "bd" (i)				\
+		: "da" (&v->counter), "br" (i)				\
 		: "cc");						\
 									\
 	smp_mb();							\
-- 
2.4.10

Re: [PATCH] metag: Fix atomic_*_return inline asm constraints

[Peter Zijlstra]

On Tue, May 03, 2016 at 09:40:59AM +0100, James Hogan wrote:
> The argument i of atomic_*_return() operations is given to inline asm
> with the "bd" constraint, which means "An Op2 register where Op1 is a
> data unit register and the instruction supports O2R", however Op1 is
> constrained by "da" which allows an address unit register to be used.
> 
> Fix the constraint to use "br", meaning "An Op2 register and the
> instruction supports O2R", i.e. not requiring Op1 to be a data unit
> register.
> 
> Fixes: d6dfe2509da9 ("locking,arch,metag: Fold atomic_ops")
> Signed-off-by: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
> Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
> Cc: linux-metag-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

Thanks James, I'd give an ack, but I really don't know about these funny
constraints you have, so I'm not sure it'd actually mean something.

Re: [PATCH] metag: Fix atomic_*_return inline asm constraints

[James Hogan]

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On Tue, May 03, 2016 at 10:52:46AM +0200, Peter Zijlstra wrote:
> On Tue, May 03, 2016 at 09:40:59AM +0100, James Hogan wrote:
> > The argument i of atomic_*_return() operations is given to inline asm
> > with the "bd" constraint, which means "An Op2 register where Op1 is a
> > data unit register and the instruction supports O2R", however Op1 is
> > constrained by "da" which allows an address unit register to be used.
> > 
> > Fix the constraint to use "br", meaning "An Op2 register and the
> > instruction supports O2R", i.e. not requiring Op1 to be a data unit
> > register.
> > 
> > Fixes: d6dfe2509da9 ("locking,arch,metag: Fold atomic_ops")
> > Signed-off-by: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
> > Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
> > Cc: linux-metag-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> 
> Thanks James, I'd give an ack, but I really don't know about these funny
> constraints you have, so I'm not sure it'd actually mean something.

No problem, meta is quite a quirky and non-orthogonal architecture. I've
applied anyway.

Thanks
James

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