Messages in this thread | | | Date | Mon, 4 Apr 2016 15:12:05 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH 3/3] locking,arm64: Introduce cmpwait() |
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On Mon, Apr 04, 2016 at 02:22:53PM +0200, Peter Zijlstra wrote: > +#define __CMPWAIT_GEN(w, sz, name) \
+static inline \
> +void __cmpwait_case_##name(volatile void *ptr, unsigned long val) \ > +{ \ > + unsigned long tmp; \ > + \ > + asm volatile( \ > + " ldxr" #sz "\t%" #w "[tmp], %[v]\n" \ > + " eor %" #w "[tmp], %" #w "[tmp], %" #w "[val]\n" \ > + " cbnz %" #w "[tmp], 1f\n" \ > + " wfe\n" \ > + "1:" \ > + : [tmp] "=&r" (tmp), [val] "=&r" (val), \ > + [v] "+Q" (*(unsigned long *)ptr)); \
And this probably wants a "memory" clobber to force reload values after this returns.
> +}
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