On Mon, May 6, 2013 at 1:01 PM, Will Deacon <will.deacon@xxxxxxx> wrote: > The Alpha Architecture Reference Manual states that any memory access > performed between an LD_xL and a STx_C instruction may cause the > store-conditional to fail unconditionally and, as such, `no useful > program should do this'. > > Linux is a useful program, so fix up the Alpha spinlock implementation > to use logical operations rather than load-address instructions for > generating immediates. > > Cc: Richard Henderson <rth@xxxxxxxxxxx> > Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx> > Cc: Matt Turner <mattst88@xxxxxxxxx> > Signed-off-by: Will Deacon <will.deacon@xxxxxxx> > --- > arch/alpha/include/asm/spinlock.h | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/arch/alpha/include/asm/spinlock.h b/arch/alpha/include/asm/spinlock.h > index 3bba21e..0c357cd 100644 > --- a/arch/alpha/include/asm/spinlock.h > +++ b/arch/alpha/include/asm/spinlock.h > @@ -29,7 +29,7 @@ static inline void arch_spin_lock(arch_spinlock_t * lock) > __asm__ __volatile__( > "1: ldl_l %0,%1\n" > " bne %0,2f\n" > - " lda %0,1\n" > + " mov 1,%0\n" > " stl_c %0,%1\n" > " beq %0,2f\n" > " mb\n" > @@ -86,7 +86,7 @@ static inline void arch_write_lock(arch_rwlock_t *lock) > __asm__ __volatile__( > "1: ldl_l %1,%0\n" > " bne %1,6f\n" > - " lda %1,1\n" > + " mov 1,%1\n" > " stl_c %1,%0\n" > " beq %1,6f\n" > " mb\n" > @@ -106,7 +106,7 @@ static inline int arch_read_trylock(arch_rwlock_t * lock) > > __asm__ __volatile__( > "1: ldl_l %1,%0\n" > - " lda %2,0\n" > + " mov 0,%2\n" > " blbs %1,2f\n" > " subl %1,2,%2\n" > " stl_c %2,%0\n" > @@ -128,9 +128,9 @@ static inline int arch_write_trylock(arch_rwlock_t * lock) > > __asm__ __volatile__( > "1: ldl_l %1,%0\n" > - " lda %2,0\n" > + " mov 0,%2\n" > " bne %1,2f\n" > - " lda %2,1\n" > + " mov 1,%2\n" > " stl_c %2,%0\n" > " beq %2,6f\n" > "2: mb\n" > -- > 1.8.2.2 I'm not sure of the interpretation that LDA counts as a memory access. The manual says it's Ra <- Rbv + SEXT(disp). It's not touching memory that I can see. Does this fix a known problem or is it just something that you noticed? Matt -- To unsubscribe from this list: send the line "unsubscribe linux-alpha" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
