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Message-ID: <20131107133625.GU10651@twins.programming.kicks-ass.net>
Date: Thu, 7 Nov 2013 14:36:25 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Will Deacon <will.deacon@....com>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Victor Kaplansky <VICTORK@...ibm.com>,
Oleg Nesterov <oleg@...hat.com>,
Anton Blanchard <anton@...ba.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Frederic Weisbecker <fweisbec@...il.com>,
LKML <linux-kernel@...r.kernel.org>,
Linux PPC dev <linuxppc-dev@...abs.org>,
Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
Michael Ellerman <michael@...erman.id.au>,
Michael Neuling <mikey@...ling.org>,
Russell King <linux@....linux.org.uk>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Tony Luck <tony.luck@...el.com>
Subject: Re: [RFC] arch: Introduce new TSO memory barrier smp_tmb()
On Thu, Nov 07, 2013 at 11:17:41AM +0000, Will Deacon wrote:
> Hi Peter,
>
> Couple of minor fixes on the arm64 side...
>
> On Wed, Nov 06, 2013 at 01:57:36PM +0000, Peter Zijlstra wrote:
> > --- a/arch/arm64/include/asm/barrier.h
> > +++ b/arch/arm64/include/asm/barrier.h
> > @@ -35,11 +35,59 @@
> > #define smp_mb() barrier()
> > #define smp_rmb() barrier()
> > #define smp_wmb() barrier()
> > +
> > +#define smp_store_release(p, v) \
> > +do { \
> > + compiletime_assert_atomic_type(*p); \
> > + smp_mb(); \
> > + ACCESS_ONCE(*p) = (v); \
> > +} while (0)
> > +
> > +#define smp_load_acquire(p) \
> > +({ \
> > + typeof(*p) ___p1 = ACCESS_ONCE(*p); \
> > + compiletime_assert_atomic_type(*p); \
> > + smp_mb(); \
> > + ___p1; \
> > +})
> > +
> > #else
> > +
> > #define smp_mb() asm volatile("dmb ish" : : : "memory")
> > #define smp_rmb() asm volatile("dmb ishld" : : : "memory")
> > #define smp_wmb() asm volatile("dmb ishst" : : : "memory")
> > -#endif
>
> Why are you getting rid of this #endif?
oops..
> > +#define smp_store_release(p, v) \
> > +do { \
> > + compiletime_assert_atomic_type(*p); \
> > + switch (sizeof(*p)) { \
> > + case 4: \
> > + asm volatile ("stlr %w1, [%0]" \
> > + : "=Q" (*p) : "r" (v) : "memory"); \
> > + break; \
> > + case 8: \
> > + asm volatile ("stlr %1, [%0]" \
> > + : "=Q" (*p) : "r" (v) : "memory"); \
> > + break; \
> > + } \
> > +} while (0)
> > +
> > +#define smp_load_acquire(p) \
> > +({ \
> > + typeof(*p) ___p1; \
> > + compiletime_assert_atomic_type(*p); \
> > + switch (sizeof(*p)) { \
> > + case 4: \
> > + asm volatile ("ldar %w0, [%1]" \
> > + : "=r" (___p1) : "Q" (*p) : "memory"); \
> > + break; \
> > + case 8: \
> > + asm volatile ("ldar %0, [%1]" \
> > + : "=r" (___p1) : "Q" (*p) : "memory"); \
> > + break; \
> > + } \
> > + ___p1; \
> > +})
>
> You don't need the square brackets when using the "Q" constraint (otherwise
> it will expand to something like [[x0]], which gas won't accept).
>
> With those changes, for the general idea and arm/arm64 parts:
>
> Acked-by: Will Deacon <will.deacon@....com>
Thanks, I did that split-up I talked about yesterday, I was going to
compile them for all archs I have a compiler for before posting again.
---
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -62,11 +62,11 @@ do { \
compiletime_assert_atomic_type(*p); \
switch (sizeof(*p)) { \
case 4: \
- asm volatile ("stlr %w1, [%0]" \
+ asm volatile ("stlr %w1, %0" \
: "=Q" (*p) : "r" (v) : "memory"); \
break; \
case 8: \
- asm volatile ("stlr %1, [%0]" \
+ asm volatile ("stlr %1, %0" \
: "=Q" (*p) : "r" (v) : "memory"); \
break; \
} \
@@ -78,17 +78,19 @@ do { \
compiletime_assert_atomic_type(*p); \
switch (sizeof(*p)) { \
case 4: \
- asm volatile ("ldar %w0, [%1]" \
+ asm volatile ("ldar %w0, %1" \
: "=r" (___p1) : "Q" (*p) : "memory"); \
break; \
case 8: \
- asm volatile ("ldar %0, [%1]" \
+ asm volatile ("ldar %0, %1" \
: "=r" (___p1) : "Q" (*p) : "memory"); \
break; \
} \
___p1; \
})
+#endif
+
#define read_barrier_depends() do { } while(0)
#define smp_read_barrier_depends() do { } while(0)
--
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