On Fri, Apr 22, 2016 at 11:04:31AM +0200, Peter Zijlstra wrote:
> Implement FETCH-OP atomic primitives, these are very similar to the
> existing OP-RETURN primitives we already have, except they return the
> value of the atomic variable _before_ modification.
>
> This is especially useful for irreversible operations -- such as
> bitops (because it becomes impossible to reconstruct the state prior
> to modification).
>
>
> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
> ---
> arch/powerpc/include/asm/atomic.h | 83
> +++++++++++++++++++++++++++++++++-----
> 1 file changed, 74 insertions(+), 9 deletions(-)
>
> --- a/arch/powerpc/include/asm/atomic.h
> +++ b/arch/powerpc/include/asm/atomic.h
> @@ -78,21 +78,53 @@ static inline int atomic_##op##_return_r
> return t; \
> }
>
> +#define ATOMIC_FETCH_OP_RELAXED(op, asm_op) \
> +static inline int atomic_fetch_##op##_relaxed(int a, atomic_t *v) \
> +{ \
> + int res, t; \
> + \
> + __asm__ __volatile__( \
> +"1: lwarx %0,0,%4 # atomic_fetch_" #op "_relaxed\n" \
> + #asm_op " %1,%2,%0\n" \
Should be
#asm_op " %1,%3,%0\n"
right? Because %2 is v->counter and %3 is @a.
Regards,
Boqun
> + PPC405_ERR77(0, %4) \
> +" stwcx. %1,0,%4\n" \
> +" bne- 1b\n" \
> + : "=&r" (res), "=&r" (t), "+m" (v->counter) \
> + : "r" (a), "r" (&v->counter) \
> + : "cc"); \
> + \
> + return res; \
> +}
> +
> #define ATOMIC_OPS(op, asm_op)
> \
> ATOMIC_OP(op, asm_op) \
> - ATOMIC_OP_RETURN_RELAXED(op, asm_op)
> + ATOMIC_OP_RETURN_RELAXED(op, asm_op) \
> + ATOMIC_FETCH_OP_RELAXED(op, asm_op)
>
> ATOMIC_OPS(add, add)
> ATOMIC_OPS(sub, subf)
>
> -ATOMIC_OP(and, and)
> -ATOMIC_OP(or, or)
> -ATOMIC_OP(xor, xor)
> -
> #define atomic_add_return_relaxed atomic_add_return_relaxed
> #define atomic_sub_return_relaxed atomic_sub_return_relaxed
>
> +#define atomic_fetch_add_relaxed atomic_fetch_add_relaxed
> +#define atomic_fetch_sub_relaxed atomic_fetch_sub_relaxed
> +
> +#undef ATOMIC_OPS
> +#define ATOMIC_OPS(op, asm_op)
> \
> + ATOMIC_OP(op, asm_op) \
> + ATOMIC_FETCH_OP_RELAXED(op, asm_op)
> +
> +ATOMIC_OPS(and, and)
> +ATOMIC_OPS(or, or)
> +ATOMIC_OPS(xor, xor)
> +
> +#define atomic_fetch_and_relaxed atomic_fetch_and_relaxed
> +#define atomic_fetch_or_relaxed atomic_fetch_or_relaxed
> +#define atomic_fetch_xor_relaxed atomic_fetch_xor_relaxed
> +
> #undef ATOMIC_OPS
> +#undef ATOMIC_FETCH_OP_RELAXED
> #undef ATOMIC_OP_RETURN_RELAXED
> #undef ATOMIC_OP
>
> @@ -329,20 +361,53 @@ atomic64_##op##_return_relaxed(long a, a
> return t; \
> }
>
> +#define ATOMIC64_FETCH_OP_RELAXED(op, asm_op)
> \
> +static inline long \
> +atomic64_fetch_##op##_relaxed(long a, atomic64_t *v) \
> +{ \
> + long res, t; \
> + \
> + __asm__ __volatile__( \
> +"1: ldarx %0,0,%4 # atomic64_fetch_" #op "_relaxed\n" \
> + #asm_op " %1,%3,%0\n" \
> +" stdcx. %1,0,%4\n" \
> +" bne- 1b\n" \
> + : "=&r" (res), "=&r" (t), "+m" (v->counter) \
> + : "r" (a), "r" (&v->counter) \
> + : "cc"); \
> + \
> + return t; \
> +}
> +
> #define ATOMIC64_OPS(op, asm_op) \
> ATOMIC64_OP(op, asm_op) \
> - ATOMIC64_OP_RETURN_RELAXED(op, asm_op)
> + ATOMIC64_OP_RETURN_RELAXED(op, asm_op) \
> + ATOMIC64_FETCH_OP_RELAXED(op, asm_op)
>
> ATOMIC64_OPS(add, add)
> ATOMIC64_OPS(sub, subf)
> -ATOMIC64_OP(and, and)
> -ATOMIC64_OP(or, or)
> -ATOMIC64_OP(xor, xor)
>
> #define atomic64_add_return_relaxed atomic64_add_return_relaxed
> #define atomic64_sub_return_relaxed atomic64_sub_return_relaxed
>
> +#define atomic64_fetch_add_relaxed atomic64_fetch_add_relaxed
> +#define atomic64_fetch_sub_relaxed atomic64_fetch_sub_relaxed
> +
> +#undef ATOMIC64_OPS
> +#define ATOMIC64_OPS(op, asm_op) \
> + ATOMIC64_OP(op, asm_op) \
> + ATOMIC64_FETCH_OP_RELAXED(op, asm_op)
> +
> +ATOMIC64_OPS(and, and)
> +ATOMIC64_OPS(or, or)
> +ATOMIC64_OPS(xor, xor)
> +
> +#define atomic64_fetch_and_relaxed atomic64_fetch_and_relaxed
> +#define atomic64_fetch_or_relaxed atomic64_fetch_or_relaxed
> +#define atomic64_fetch_xor_relaxed atomic64_fetch_xor_relaxed
> +
> #undef ATOPIC64_OPS
> +#undef ATOMIC64_FETCH_OP_RELAXED
> #undef ATOMIC64_OP_RETURN_RELAXED
> #undef ATOMIC64_OP
>
>
>
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