On Sat, Apr 30, 2016 at 01:20:31AM +0100, James Hogan wrote:
> > + asm volatile ( \
> > + "1: LNKGETD %1, [%2]\n" \
> > + " " #op " %0, %1, %3\n" \
>
> i was hoping never to have to think about meta asm constraints again :-P
There is a solution for that: rm -rf arch/metag :-)
> and/or/xor are only available in the data units, as determined by %1 in
> this case, so the constraint for result shouldn't have "a" in it.
>
> diff --git a/arch/metag/include/asm/atomic_lnkget.h
> b/arch/metag/include/asm/atomic_lnkget.h
> index 50ad05050947..def2c642f053 100644
> --- a/arch/metag/include/asm/atomic_lnkget.h
> +++ b/arch/metag/include/asm/atomic_lnkget.h
> @@ -84,7 +84,7 @@ static inline int atomic_fetch_##op(int i, atomic_t *v)
> \
> " ANDT %0, %0, #HI(0x3f000000)\n" \
> " CMPT %0, #HI(0x02000000)\n" \
> " BNZ 1b\n" \
> - : "=&d" (temp), "=&da" (result) \
> + : "=&d" (temp), "=&d" (result) \
> : "da" (&v->counter), "bd" (i) \
> : "cc"); \
>
> That also ensures the "bd" constraint for %3 (meaning "an op2 register
> where op1 [%1 in this case] is a data unit register and the instruction
> supports O2R") is consistent.
>
> So with that change this patch looks good to me:
Right, so I'd _never_ have thought to look at that,
> Acked-by: James Hogan <james.ho...@imgtec.com>
Thanks!
> Note that for the ATOMIC_OP_RETURN() case (add/sub only) either address
> or data units can be used (hence the "da" for %1), but then the "bd"
> constraint on %3 is wrong as op1 [%1] may not be in data unit (sorry I
> didn't spot that at the time). I'll queue a fix, something like below
> probably ("br" means "An Op2 register and the instruction supports O2R",
> i.e. op1/%1 doesn't have to be a data unit register):
>
> diff --git a/arch/metag/include/asm/atomic_lnkget.h
> b/arch/metag/include/asm/atomic_lnkget.h
> index 50ad05050947..def2c642f053 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(); \
> \
> \
Thanks, again :-)
