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locking/atomic, arch/xtensa: Implement atomic_fetch_{add,sub,and,or,xor}()
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) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Zankel <chris@zankel.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-xtensa@linux-xtensa.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -98,6 +98,26 @@ static inline int atomic_##op##_return(int i, atomic_t * v) \
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return result; \
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return result; \
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}
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}
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#define ATOMIC_FETCH_OP(op) \
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static inline int atomic_fetch_##op(int i, atomic_t * v) \
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{ \
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unsigned long tmp; \
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int result; \
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\
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__asm__ __volatile__( \
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"1: l32i %1, %3, 0\n" \
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" wsr %1, scompare1\n" \
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" " #op " %0, %1, %2\n" \
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" s32c1i %0, %3, 0\n" \
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" bne %0, %1, 1b\n" \
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: "=&a" (result), "=&a" (tmp) \
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: "a" (i), "a" (v) \
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: "memory" \
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); \
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\
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return result; \
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}
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#else /* XCHAL_HAVE_S32C1I */
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#else /* XCHAL_HAVE_S32C1I */
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#define ATOMIC_OP(op) \
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#define ATOMIC_OP(op) \
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@ -138,18 +158,44 @@ static inline int atomic_##op##_return(int i, atomic_t * v) \
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return vval; \
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return vval; \
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}
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}
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#define ATOMIC_FETCH_OP(op) \
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static inline int atomic_fetch_##op(int i, atomic_t * v) \
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{ \
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unsigned int tmp, vval; \
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\
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__asm__ __volatile__( \
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" rsil a15,"__stringify(TOPLEVEL)"\n" \
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" l32i %0, %3, 0\n" \
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" " #op " %1, %0, %2\n" \
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" s32i %1, %3, 0\n" \
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" wsr a15, ps\n" \
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" rsync\n" \
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: "=&a" (vval), "=&a" (tmp) \
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: "a" (i), "a" (v) \
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: "a15", "memory" \
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); \
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\
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return vval; \
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}
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#endif /* XCHAL_HAVE_S32C1I */
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#endif /* XCHAL_HAVE_S32C1I */
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#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
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#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op) ATOMIC_OP_RETURN(op)
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ATOMIC_OPS(add)
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ATOMIC_OPS(add)
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ATOMIC_OPS(sub)
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ATOMIC_OPS(sub)
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ATOMIC_OP(and)
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#undef ATOMIC_OPS
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ATOMIC_OP(or)
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#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op)
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ATOMIC_OP(xor)
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#define atomic_fetch_or atomic_fetch_or
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ATOMIC_OPS(and)
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ATOMIC_OPS(or)
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ATOMIC_OPS(xor)
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#undef ATOMIC_OPS
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#undef ATOMIC_OPS
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#undef ATOMIC_FETCH_OP
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#undef ATOMIC_OP_RETURN
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#undef ATOMIC_OP_RETURN
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#undef ATOMIC_OP
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#undef ATOMIC_OP
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