On Sun, Oct 12, 2008 at 07:47:32AM +0200, Nick Piggin wrote:
> +static inline int __mutex_cmpxchg_lock(atomic_t *v, int old, int new)
> +{
> +     int t;
> +
> +     __asm__ __volatile__ (
> +"1:  lwarx   %0,0,%1         # mutex trylock\n\
> +     cmpw    0,%0,%2\n\
> +     bne-    2f\n"
> +     PPC405_ERR77(0,%1)
> +"    stwcx.  %3,0,%1\n\
> +     bne-    1b"
> +     ISYNC_ON_SMP
> +     "\n\
> +2:"
> +     : "=&r" (t)
> +     : "r" (&v->counter), "r" (old), "r" (new)
> +     : "cc", "memory");

This will break if the compiler picks r0 for &v->counter.  Use "b" as the
constraint, or better yet do "lwarx %0, %y1", with a "Z" (v->counter)
constraint.

-Scott
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