Subject: [PATCH 6/9] arm64: Add new routine local_disable

From: [email-masked] (Mark Rutland)
Date: Tue, 26 Aug 2014 17:23:24 +0100

On Tue, Aug 26, 2014 at 05:04:43PM +0100, Catalin Marinas wrote:
> On Fri, Aug 22, 2014 at 08:49:16PM +0100, Geoff Levand wrote:
> > Add the new arm64 routine local_disable() to allow the masking of several DAIF
> > flags in one operation.  Currently, we only have routines to mask individual
> > flags, and to mask several flags multiple calls to daifset are required.
> > 
> > Signed-off-by: Geoff Levand <[email-masked]>
> > ---
> >  arch/arm64/include/asm/irqflags.h | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
> > 
> > diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h
> > index 11cc941..28521d4 100644
> > --- a/arch/arm64/include/asm/irqflags.h
> > +++ b/arch/arm64/include/asm/irqflags.h
> > @@ -113,5 +113,18 @@ static inline int arch_irqs_disabled_flags(unsigned long flags)
> >  #define local_dbg_enable()	asm("msr	daifclr, #8" : : : "memory")
> >  #define local_dbg_disable()	asm("msr	daifset, #8" : : : "memory")
> >  
> > +enum daif_flag {
> > +	DAIF_FIQ   = (1UL << 6),
> > +	DAIF_IRQ   = (1UL << 7),
> > +	DAIF_ASYNC = (1UL << 8),
> > +	DAIF_DBG   = (1UL << 9),
> > +	DAIF_ALL   = (0xffUL << 6),
> > +};
> > +
> > +static inline void local_disable(unsigned long daif_flags)
> > +{
> > +	arch_local_irq_restore(daif_flags | arch_local_save_flags());
> > +}
> 
> Who's using this function? I don't see any patch in this series calling
> it.

This was for implementing the spin-table cpu-return-addr idea. Before
returning to the spin-table we need to mask everything, and not doing
that as four back-to-back context-synchronizing writes would be nice.

It should probably be introduced by the cpu-return-addr series unless
this is useful elsewhere. If we don't actually have another use, we
could just have a msr daifset, #0xf (arch_local_disable_all?).

Thanks,
Mark.