[RFC][PATCH 05/31] locking,arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()

From: Peter Zijlstra
Date: Fri Apr 22 2016 - 05:59:56 EST

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).

XXX lacking LSE bits


Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/arm64/include/asm/atomic.h | 32 ++++++++++
arch/arm64/include/asm/atomic_ll_sc.h | 108 ++++++++++++++++++++++++++--------
2 files changed, 116 insertions(+), 24 deletions(-)

--- a/arch/arm64/include/asm/atomic.h
+++ b/arch/arm64/include/asm/atomic.h
@@ -76,6 +76,36 @@
#define atomic_dec_return_release(v) atomic_sub_return_release(1, (v))
#define atomic_dec_return(v) atomic_sub_return(1, (v))

+#define atomic_fetch_add_relaxed atomic_fetch_add_relaxed
+#define atomic_fetch_add_acquire atomic_fetch_add_acquire
+#define atomic_fetch_add_release atomic_fetch_add_release
+#define atomic_fetch_add atomic_fetch_add
+
+#define atomic_fetch_sub_relaxed atomic_fetch_sub_relaxed
+#define atomic_fetch_sub_acquire atomic_fetch_sub_acquire
+#define atomic_fetch_sub_release atomic_fetch_sub_release
+#define atomic_fetch_sub atomic_fetch_sub
+
+#define atomic_fetch_and_relaxed atomic_fetch_and_relaxed
+#define atomic_fetch_and_acquire atomic_fetch_and_acquire
+#define atomic_fetch_and_release atomic_fetch_and_release
+#define atomic_fetch_and atomic_fetch_and
+
+#define atomic_fetch_andnot_relaxed atomic_fetch_andnot_relaxed
+#define atomic_fetch_andnot_acquire atomic_fetch_andnot_acquire
+#define atomic_fetch_andnot_release atomic_fetch_andnot_release
+#define atomic_fetch_andnot atomic_fetch_andnot
+
+#define atomic_fetch_or_relaxed atomic_fetch_or_relaxed
+#define atomic_fetch_or_acquire atomic_fetch_or_acquire
+#define atomic_fetch_or_release atomic_fetch_or_release
+#define atomic_fetch_or atomic_fetch_or
+
+#define atomic_fetch_xor_relaxed atomic_fetch_xor_relaxed
+#define atomic_fetch_xor_acquire atomic_fetch_xor_acquire
+#define atomic_fetch_xor_release atomic_fetch_xor_release
+#define atomic_fetch_xor atomic_fetch_xor
+
#define atomic_xchg_relaxed(v, new) xchg_relaxed(&((v)->counter), (new))
#define atomic_xchg_acquire(v, new) xchg_acquire(&((v)->counter), (new))
#define atomic_xchg_release(v, new) xchg_release(&((v)->counter), (new))
@@ -98,6 +128,8 @@
#define __atomic_add_unless(v, a, u) ___atomic_add_unless(v, a, u,)
#define atomic_andnot atomic_andnot

+#define atomic_fetch_or atomic_fetch_or
+
/*
* 64-bit atomic operations.
*/
--- a/arch/arm64/include/asm/atomic_ll_sc.h
+++ b/arch/arm64/include/asm/atomic_ll_sc.h
@@ -77,25 +77,55 @@ __LL_SC_PREFIX(atomic_##op##_return##nam
} \
__LL_SC_EXPORT(atomic_##op##_return##name);

+#define ATOMIC_FETCH_OP(name, mb, acq, rel, cl, op, asm_op) \
+__LL_SC_INLINE int \
+__LL_SC_PREFIX(atomic_fetch_##op##name(int i, atomic_t *v)) \
+{ \
+ unsigned long tmp; \
+ int val, result; \
+ \
+ asm volatile("// atomic_fetch_" #op #name "\n" \
+" prfm pstl1strm, %3\n" \
+"1: ld" #acq "xr %w0, %3\n" \
+" " #asm_op " %w1, %w0, %w4\n" \
+" st" #rel "xr %w2, %w1, %3\n" \
+" cbnz %w2, 1b\n" \
+" " #mb \
+ : "=&r" (result), "=&r" (val), "=&r" (tmp), "+Q" (v->counter) \
+ : "Ir" (i) \
+ : cl); \
+ \
+ return result; \
+} \
+__LL_SC_EXPORT(atomic_fetch_##op##name);
+
#define ATOMIC_OPS(...) \
ATOMIC_OP(__VA_ARGS__) \
- ATOMIC_OP_RETURN( , dmb ish, , l, "memory", __VA_ARGS__)
-
-#define ATOMIC_OPS_RLX(...) \
- ATOMIC_OPS(__VA_ARGS__) \
+ ATOMIC_OP_RETURN( , dmb ish, , l, "memory", __VA_ARGS__)\
ATOMIC_OP_RETURN(_relaxed, , , , , __VA_ARGS__)\
ATOMIC_OP_RETURN(_acquire, , a, , "memory", __VA_ARGS__)\
- ATOMIC_OP_RETURN(_release, , , l, "memory", __VA_ARGS__)
+ ATOMIC_OP_RETURN(_release, , , l, "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP ( , dmb ish, , l, "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_relaxed, , , , , __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_acquire, , a, , "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_release, , , l, "memory", __VA_ARGS__)

-ATOMIC_OPS_RLX(add, add)
-ATOMIC_OPS_RLX(sub, sub)
+ATOMIC_OPS(add, add)
+ATOMIC_OPS(sub, sub)

-ATOMIC_OP(and, and)
-ATOMIC_OP(andnot, bic)
-ATOMIC_OP(or, orr)
-ATOMIC_OP(xor, eor)
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(...) \
+ ATOMIC_OP(__VA_ARGS__) \
+ ATOMIC_FETCH_OP ( , dmb ish, , l, "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_relaxed, , , , , __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_acquire, , a, , "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_release, , , l, "memory", __VA_ARGS__)
+
+ATOMIC_OPS(and, and)
+ATOMIC_OPS(andnot, bic)
+ATOMIC_OPS(or, orr)
+ATOMIC_OPS(xor, eor)

-#undef ATOMIC_OPS_RLX
#undef ATOMIC_OPS
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
@@ -140,25 +170,55 @@ __LL_SC_PREFIX(atomic64_##op##_return##n
} \
__LL_SC_EXPORT(atomic64_##op##_return##name);

+#define ATOMIC64_FETCH_OP(name, mb, acq, rel, cl, op, asm_op) \
+__LL_SC_INLINE long \
+__LL_SC_PREFIX(atomic64_fetch_##op##name(long i, atomic64_t *v)) \
+{ \
+ long result, val; \
+ unsigned long tmp; \
+ \
+ asm volatile("// atomic64_fetch_" #op #name "\n" \
+" prfm pstl1strm, %3\n" \
+"1: ld" #acq "xr %0, %3\n" \
+" " #asm_op " %1, %0, %4\n" \
+" st" #rel "xr %w2, %1, %3\n" \
+" cbnz %w2, 1b\n" \
+" " #mb \
+ : "=&r" (result), "=&r" (val), "=&r" (tmp), "+Q" (v->counter) \
+ : "Ir" (i) \
+ : cl); \
+ \
+ return result; \
+} \
+__LL_SC_EXPORT(atomic64_##op##_return##name);
+
#define ATOMIC64_OPS(...) \
ATOMIC64_OP(__VA_ARGS__) \
- ATOMIC64_OP_RETURN(, dmb ish, , l, "memory", __VA_ARGS__)
-
-#define ATOMIC64_OPS_RLX(...) \
- ATOMIC64_OPS(__VA_ARGS__) \
+ ATOMIC64_OP_RETURN(, dmb ish, , l, "memory", __VA_ARGS__) \
ATOMIC64_OP_RETURN(_relaxed,, , , , __VA_ARGS__) \
ATOMIC64_OP_RETURN(_acquire,, a, , "memory", __VA_ARGS__) \
- ATOMIC64_OP_RETURN(_release,, , l, "memory", __VA_ARGS__)
+ ATOMIC64_OP_RETURN(_release,, , l, "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (, dmb ish, , l, "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_relaxed,, , , , __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_acquire,, a, , "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_release,, , l, "memory", __VA_ARGS__)

-ATOMIC64_OPS_RLX(add, add)
-ATOMIC64_OPS_RLX(sub, sub)
+ATOMIC64_OPS(add, add)
+ATOMIC64_OPS(sub, sub)

-ATOMIC64_OP(and, and)
-ATOMIC64_OP(andnot, bic)
-ATOMIC64_OP(or, orr)
-ATOMIC64_OP(xor, eor)
+#undef ATOMIC_OPS
+#define ATOMIC64_OPS(...) \
+ ATOMIC64_OP(__VA_ARGS__) \
+ ATOMIC64_FETCH_OP (, dmb ish, , l, "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_relaxed,, , , , __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_acquire,, a, , "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_release,, , l, "memory", __VA_ARGS__)
+
+ATOMIC64_OPS(and, and)
+ATOMIC64_OPS(andnot, bic)
+ATOMIC64_OPS(or, orr)
+ATOMIC64_OPS(xor, eor)

-#undef ATOMIC64_OPS_RLX
#undef ATOMIC64_OPS
#undef ATOMIC64_OP_RETURN
#undef ATOMIC64_OP