Re: [Xen-devel] [PATCH 10/10] xen: arm: use more specific barriers for read and write barriers.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2013-07-04 at 12:42 +0100, Tim Deegan wrote:
> At 17:10 +0100 on 28 Jun (1372439456), Ian Campbell wrote:
> > Note that 32-bit does not provide a load variant of the inner shareable
> > barrier, so that remains a full any-any barrier.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > ---
> >  xen/include/asm-arm/system.h |   13 +++++++++----
> >  1 files changed, 9 insertions(+), 4 deletions(-)
> > 
> > diff --git a/xen/include/asm-arm/system.h b/xen/include/asm-arm/system.h
> > index 7c3e42d..efaf645 100644
> > --- a/xen/include/asm-arm/system.h
> > +++ b/xen/include/asm-arm/system.h
> > @@ -17,12 +17,17 @@
> >  #define dmb(scope)      asm volatile("dmb " scope : : : "memory")
> >  
> >  #define mb()            dsb("sy")
> > -#define rmb()           dsb("sy")
> > -#define wmb()           dsb("sy")
> > +#define rmb()           dsb("ld")
> 
> This doesn't exist on arm32; it'll have to be dsb("sy") there, just like
> you've done for smb_rmb() below.

Right, suggests that rmb isn't actually used anywhere (since I'm sure I
compile tested) but lets at least make it correct...

> 
> With that change, Acked-by: Tim Deegan <tim@xxxxxxx>

Thanks,
Ian.

> 
> > +#define wmb()           dsb("st")
> >  
> >  #define smp_mb()        dmb("ish")
> > -#define smp_rmb()       dmb("ish")
> > -#define smp_wmb()       dmb("ish")
> > +#ifdef CONFIG_ARM_64
> > +#define smp_rmb()       dmb("ishld")
> > +#else
> > +#define smp_rmb()       dmb("ish") /* 32-bit has no ishld variant. */
> > +#endif
> > +
> > +#define smp_wmb()       dmb("ishst")
> >  
> >  #define xchg(ptr,x) \
> >          ((__typeof__(*(ptr)))__xchg((unsigned 
> > long)(x),(ptr),sizeof(*(ptr))))
> > -- 
> > 1.7.2.5
> > 
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxx
> > http://lists.xen.org/xen-devel



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