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SubjectRe: [PATCH V2 11/19] csky: Atomic operations
On Thu, Jul 05, 2018 at 08:00:08PM +0200, Peter Zijlstra wrote:
> On Mon, Jul 02, 2018 at 01:30:14AM +0800, Guo Ren wrote:
> > +#ifdef CONFIG_CPU_HAS_LDSTEX
> > +ENTRY(csky_cmpxchg)
> > + USPTOKSP
> > + mfcr a3, epc
> > + INCTRAP a3
> > +
> > + subi sp, 8
> > + stw a3, (sp, 0)
> > + mfcr a3, epsr
> > + stw a3, (sp, 4)
> > +
> > + psrset ee
> > +1:
> > + ldex a3, (a2)
> > + cmpne a0, a3
> > + bt16 2f
> > + mov a3, a1
> > + stex a3, (a2)
> > + bez a3, 1b
> > +2:
> > + sync.is
> > + mvc a0
> > + ldw a3, (sp, 0)
> > + mtcr a3, epc
> > + ldw a3, (sp, 4)
> > + mtcr a3, epsr
> > + addi sp, 8
> > + KSPTOUSP
> > + rte
> > +END(csky_cmpxchg)
> > +#else
>
> Please explain... if the CPU has LDEX/STEX, then _why_ do you need this?
Our libc use csky_cmpxchg and we want it compatible. Of course, we'll
also implement the ldex/stex atomic operations in libs in future.

Guo Ren

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