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[109.80.100.85]) by smtp.gmail.com with ESMTPSA id t135sm931958wmt.44.2018.03.09.04.13.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 09 Mar 2018 04:13:54 -0800 (PST) From: Andrea Parri To: Palmer Dabbelt , Albert Ou Cc: Daniel Lustig , Alan Stern , Will Deacon , Peter Zijlstra , Boqun Feng , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , Paul McKenney , Akira Yokosawa , Ingo Molnar , Linus Torvalds , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Andrea Parri Subject: [PATCH v2 2/2] riscv/atomic: Strengthen implementations with fences Date: Fri, 9 Mar 2018 13:13:40 +0100 Message-Id: <1520597620-16650-1-git-send-email-parri.andrea@gmail.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Atomics present the same issue with locking: release and acquire variants need to be strengthened to meet the constraints defined by the Linux-kernel memory consistency model [1]. Atomics present a further issue: implementations of atomics such as atomic_cmpxchg() and atomic_add_unless() rely on LR/SC pairs, which do not give full-ordering with .aqrl; for example, current implementations allow the "lr-sc-aqrl-pair-vs-full-barrier" test below to end up with the state indicated in the "exists" clause. In order to "synchronize" LKMM and RISC-V's implementation, this commit strengthens the implementations of the atomics operations by replacing .rl and .aq with the use of ("lightweigth") fences, and by replacing .aqrl LR/SC pairs in sequences such as: 0: lr.w.aqrl %0, %addr bne %0, %old, 1f ... sc.w.aqrl %1, %new, %addr bnez %1, 0b 1: with sequences of the form: 0: lr.w %0, %addr bne %0, %old, 1f ... sc.w.rl %1, %new, %addr /* SC-release */ bnez %1, 0b fence rw, rw /* "full" fence */ 1: following Daniel's suggestion. These modifications were validated with simulation of the RISC-V memory consistency model. C lr-sc-aqrl-pair-vs-full-barrier {} P0(int *x, int *y, atomic_t *u) { int r0; int r1; WRITE_ONCE(*x, 1); r0 = atomic_cmpxchg(u, 0, 1); r1 = READ_ONCE(*y); } P1(int *x, int *y, atomic_t *v) { int r0; int r1; WRITE_ONCE(*y, 1); r0 = atomic_cmpxchg(v, 0, 1); r1 = READ_ONCE(*x); } exists (u=1 /\ v=1 /\ 0:r1=0 /\ 1:r1=0) [1] https://marc.info/?l=linux-kernel&m=151930201102853&w=2 https://groups.google.com/a/groups.riscv.org/forum/#!topic/isa-dev/hKywNHBkAXM https://marc.info/?l=linux-kernel&m=151633436614259&w=2 Suggested-by: Daniel Lustig Signed-off-by: Andrea Parri Cc: Palmer Dabbelt Cc: Albert Ou Cc: Daniel Lustig Cc: Alan Stern Cc: Will Deacon Cc: Peter Zijlstra Cc: Boqun Feng Cc: Nicholas Piggin Cc: David Howells Cc: Jade Alglave Cc: Luc Maranget Cc: "Paul E. McKenney" Cc: Akira Yokosawa Cc: Ingo Molnar Cc: Linus Torvalds Cc: linux-riscv@lists.infradead.org Cc: linux-kernel@vger.kernel.org --- arch/riscv/include/asm/atomic.h | 417 +++++++++++++++++++++++++-------------- arch/riscv/include/asm/cmpxchg.h | 391 +++++++++++++++++++++++++++++------- 2 files changed, 588 insertions(+), 220 deletions(-) diff --git a/arch/riscv/include/asm/atomic.h b/arch/riscv/include/asm/atomic.h index e65d1cd89e28b..855115ace98c8 100644 --- a/arch/riscv/include/asm/atomic.h +++ b/arch/riscv/include/asm/atomic.h @@ -24,6 +24,20 @@ #include #define ATOMIC_INIT(i) { (i) } + +#define __atomic_op_acquire(op, args...) \ +({ \ + typeof(op##_relaxed(args)) __ret = op##_relaxed(args); \ + __asm__ __volatile__(RISCV_ACQUIRE_BARRIER "" ::: "memory"); \ + __ret; \ +}) + +#define __atomic_op_release(op, args...) \ +({ \ + __asm__ __volatile__(RISCV_RELEASE_BARRIER "" ::: "memory"); \ + op##_relaxed(args); \ +}) + static __always_inline int atomic_read(const atomic_t *v) { return READ_ONCE(v->counter); @@ -50,22 +64,23 @@ static __always_inline void atomic64_set(atomic64_t *v, long i) * have the AQ or RL bits set. These don't return anything, so there's only * one version to worry about. */ -#define ATOMIC_OP(op, asm_op, I, asm_type, c_type, prefix) \ -static __always_inline void atomic##prefix##_##op(c_type i, atomic##prefix##_t *v) \ -{ \ - __asm__ __volatile__ ( \ - "amo" #asm_op "." #asm_type " zero, %1, %0" \ - : "+A" (v->counter) \ - : "r" (I) \ - : "memory"); \ -} +#define ATOMIC_OP(op, asm_op, I, asm_type, c_type, prefix) \ +static __always_inline \ +void atomic##prefix##_##op(c_type i, atomic##prefix##_t *v) \ +{ \ + __asm__ __volatile__ ( \ + " amo" #asm_op "." #asm_type " zero, %1, %0" \ + : "+A" (v->counter) \ + : "r" (I) \ + : "memory"); \ +} \ #ifdef CONFIG_GENERIC_ATOMIC64 -#define ATOMIC_OPS(op, asm_op, I) \ +#define ATOMIC_OPS(op, asm_op, I) \ ATOMIC_OP (op, asm_op, I, w, int, ) #else -#define ATOMIC_OPS(op, asm_op, I) \ - ATOMIC_OP (op, asm_op, I, w, int, ) \ +#define ATOMIC_OPS(op, asm_op, I) \ + ATOMIC_OP (op, asm_op, I, w, int, ) \ ATOMIC_OP (op, asm_op, I, d, long, 64) #endif @@ -79,75 +94,115 @@ ATOMIC_OPS(xor, xor, i) #undef ATOMIC_OPS /* - * Atomic ops that have ordered, relaxed, acquire, and relese variants. + * Atomic ops that have ordered, relaxed, acquire, and release variants. * There's two flavors of these: the arithmatic ops have both fetch and return * versions, while the logical ops only have fetch versions. */ -#define ATOMIC_FETCH_OP(op, asm_op, I, asm_or, c_or, asm_type, c_type, prefix) \ -static __always_inline c_type atomic##prefix##_fetch_##op##c_or(c_type i, atomic##prefix##_t *v) \ -{ \ - register c_type ret; \ - __asm__ __volatile__ ( \ - "amo" #asm_op "." #asm_type #asm_or " %1, %2, %0" \ - : "+A" (v->counter), "=r" (ret) \ - : "r" (I) \ - : "memory"); \ - return ret; \ +#define ATOMIC_FETCH_OP(op, asm_op, I, asm_type, c_type, prefix) \ +static __always_inline \ +c_type atomic##prefix##_fetch_##op##_relaxed(c_type i, \ + atomic##prefix##_t *v) \ +{ \ + register c_type ret; \ + __asm__ __volatile__ ( \ + " amo" #asm_op "." #asm_type " %1, %2, %0" \ + : "+A" (v->counter), "=r" (ret) \ + : "r" (I) \ + : "memory"); \ + return ret; \ +} \ +static __always_inline \ +c_type atomic##prefix##_fetch_##op(c_type i, atomic##prefix##_t *v) \ +{ \ + register c_type ret; \ + __asm__ __volatile__ ( \ + " amo" #asm_op "." #asm_type ".aqrl %1, %2, %0" \ + : "+A" (v->counter), "=r" (ret) \ + : "r" (I) \ + : "memory"); \ + return ret; \ } -#define ATOMIC_OP_RETURN(op, asm_op, c_op, I, asm_or, c_or, asm_type, c_type, prefix) \ -static __always_inline c_type atomic##prefix##_##op##_return##c_or(c_type i, atomic##prefix##_t *v) \ -{ \ - return atomic##prefix##_fetch_##op##c_or(i, v) c_op I; \ +#define ATOMIC_OP_RETURN(op, asm_op, c_op, I, asm_type, c_type, prefix) \ +static __always_inline \ +c_type atomic##prefix##_##op##_return_relaxed(c_type i, \ + atomic##prefix##_t *v) \ +{ \ + return atomic##prefix##_fetch_##op##_relaxed(i, v) c_op I; \ +} \ +static __always_inline \ +c_type atomic##prefix##_##op##_return(c_type i, atomic##prefix##_t *v) \ +{ \ + return atomic##prefix##_fetch_##op(i, v) c_op I; \ } #ifdef CONFIG_GENERIC_ATOMIC64 -#define ATOMIC_OPS(op, asm_op, c_op, I, asm_or, c_or) \ - ATOMIC_FETCH_OP (op, asm_op, I, asm_or, c_or, w, int, ) \ - ATOMIC_OP_RETURN(op, asm_op, c_op, I, asm_or, c_or, w, int, ) +#define ATOMIC_OPS(op, asm_op, c_op, I) \ + ATOMIC_FETCH_OP( op, asm_op, I, w, int, ) \ + ATOMIC_OP_RETURN(op, asm_op, c_op, I, w, int, ) #else -#define ATOMIC_OPS(op, asm_op, c_op, I, asm_or, c_or) \ - ATOMIC_FETCH_OP (op, asm_op, I, asm_or, c_or, w, int, ) \ - ATOMIC_OP_RETURN(op, asm_op, c_op, I, asm_or, c_or, w, int, ) \ - ATOMIC_FETCH_OP (op, asm_op, I, asm_or, c_or, d, long, 64) \ - ATOMIC_OP_RETURN(op, asm_op, c_op, I, asm_or, c_or, d, long, 64) +#define ATOMIC_OPS(op, asm_op, c_op, I) \ + ATOMIC_FETCH_OP( op, asm_op, I, w, int, ) \ + ATOMIC_OP_RETURN(op, asm_op, c_op, I, w, int, ) \ + ATOMIC_FETCH_OP( op, asm_op, I, d, long, 64) \ + ATOMIC_OP_RETURN(op, asm_op, c_op, I, d, long, 64) #endif -ATOMIC_OPS(add, add, +, i, , _relaxed) -ATOMIC_OPS(add, add, +, i, .aq , _acquire) -ATOMIC_OPS(add, add, +, i, .rl , _release) -ATOMIC_OPS(add, add, +, i, .aqrl, ) +ATOMIC_OPS(add, add, +, i) +ATOMIC_OPS(sub, add, +, -i) + +#define atomic_add_return_relaxed atomic_add_return_relaxed +#define atomic_sub_return_relaxed atomic_sub_return_relaxed +#define atomic_add_return atomic_add_return +#define atomic_sub_return atomic_sub_return -ATOMIC_OPS(sub, add, +, -i, , _relaxed) -ATOMIC_OPS(sub, add, +, -i, .aq , _acquire) -ATOMIC_OPS(sub, add, +, -i, .rl , _release) -ATOMIC_OPS(sub, add, +, -i, .aqrl, ) +#define atomic_fetch_add_relaxed atomic_fetch_add_relaxed +#define atomic_fetch_sub_relaxed atomic_fetch_sub_relaxed +#define atomic_fetch_add atomic_fetch_add +#define atomic_fetch_sub atomic_fetch_sub + +#ifndef CONFIG_GENERIC_ATOMIC64 +#define atomic64_add_return_relaxed atomic64_add_return_relaxed +#define atomic64_sub_return_relaxed atomic64_sub_return_relaxed +#define atomic64_add_return atomic64_add_return +#define atomic64_sub_return atomic64_sub_return + +#define atomic64_fetch_add_relaxed atomic64_fetch_add_relaxed +#define atomic64_fetch_sub_relaxed atomic64_fetch_sub_relaxed +#define atomic64_fetch_add atomic64_fetch_add +#define atomic64_fetch_sub atomic64_fetch_sub +#endif #undef ATOMIC_OPS #ifdef CONFIG_GENERIC_ATOMIC64 -#define ATOMIC_OPS(op, asm_op, I, asm_or, c_or) \ - ATOMIC_FETCH_OP(op, asm_op, I, asm_or, c_or, w, int, ) +#define ATOMIC_OPS(op, asm_op, I) \ + ATOMIC_FETCH_OP(op, asm_op, I, w, int, ) #else -#define ATOMIC_OPS(op, asm_op, I, asm_or, c_or) \ - ATOMIC_FETCH_OP(op, asm_op, I, asm_or, c_or, w, int, ) \ - ATOMIC_FETCH_OP(op, asm_op, I, asm_or, c_or, d, long, 64) +#define ATOMIC_OPS(op, asm_op, I) \ + ATOMIC_FETCH_OP(op, asm_op, I, w, int, ) \ + ATOMIC_FETCH_OP(op, asm_op, I, d, long, 64) #endif -ATOMIC_OPS(and, and, i, , _relaxed) -ATOMIC_OPS(and, and, i, .aq , _acquire) -ATOMIC_OPS(and, and, i, .rl , _release) -ATOMIC_OPS(and, and, i, .aqrl, ) +ATOMIC_OPS(and, and, i) +ATOMIC_OPS( or, or, i) +ATOMIC_OPS(xor, xor, i) -ATOMIC_OPS( or, or, i, , _relaxed) -ATOMIC_OPS( or, or, i, .aq , _acquire) -ATOMIC_OPS( or, or, i, .rl , _release) -ATOMIC_OPS( or, or, i, .aqrl, ) +#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 +#define atomic_fetch_and atomic_fetch_and +#define atomic_fetch_or atomic_fetch_or +#define atomic_fetch_xor atomic_fetch_xor -ATOMIC_OPS(xor, xor, i, , _relaxed) -ATOMIC_OPS(xor, xor, i, .aq , _acquire) -ATOMIC_OPS(xor, xor, i, .rl , _release) -ATOMIC_OPS(xor, xor, i, .aqrl, ) +#ifndef CONFIG_GENERIC_ATOMIC64 +#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 +#define atomic64_fetch_and atomic64_fetch_and +#define atomic64_fetch_or atomic64_fetch_or +#define atomic64_fetch_xor atomic64_fetch_xor +#endif #undef ATOMIC_OPS @@ -157,22 +212,24 @@ ATOMIC_OPS(xor, xor, i, .aqrl, ) /* * The extra atomic operations that are constructed from one of the core * AMO-based operations above (aside from sub, which is easier to fit above). - * These are required to perform a barrier, but they're OK this way because - * atomic_*_return is also required to perform a barrier. + * These are required to perform a full barrier, but they're OK this way + * because atomic_*_return is also required to perform a full barrier. + * */ -#define ATOMIC_OP(op, func_op, comp_op, I, c_type, prefix) \ -static __always_inline bool atomic##prefix##_##op(c_type i, atomic##prefix##_t *v) \ -{ \ - return atomic##prefix##_##func_op##_return(i, v) comp_op I; \ +#define ATOMIC_OP(op, func_op, comp_op, I, c_type, prefix) \ +static __always_inline \ +bool atomic##prefix##_##op(c_type i, atomic##prefix##_t *v) \ +{ \ + return atomic##prefix##_##func_op##_return(i, v) comp_op I; \ } #ifdef CONFIG_GENERIC_ATOMIC64 -#define ATOMIC_OPS(op, func_op, comp_op, I) \ - ATOMIC_OP (op, func_op, comp_op, I, int, ) +#define ATOMIC_OPS(op, func_op, comp_op, I) \ + ATOMIC_OP(op, func_op, comp_op, I, int, ) #else -#define ATOMIC_OPS(op, func_op, comp_op, I) \ - ATOMIC_OP (op, func_op, comp_op, I, int, ) \ - ATOMIC_OP (op, func_op, comp_op, I, long, 64) +#define ATOMIC_OPS(op, func_op, comp_op, I) \ + ATOMIC_OP(op, func_op, comp_op, I, int, ) \ + ATOMIC_OP(op, func_op, comp_op, I, long, 64) #endif ATOMIC_OPS(add_and_test, add, ==, 0) @@ -182,51 +239,87 @@ ATOMIC_OPS(add_negative, add, <, 0) #undef ATOMIC_OP #undef ATOMIC_OPS -#define ATOMIC_OP(op, func_op, I, c_type, prefix) \ -static __always_inline void atomic##prefix##_##op(atomic##prefix##_t *v) \ -{ \ - atomic##prefix##_##func_op(I, v); \ +#define ATOMIC_OP(op, func_op, I, c_type, prefix) \ +static __always_inline \ +void atomic##prefix##_##op(atomic##prefix##_t *v) \ +{ \ + atomic##prefix##_##func_op(I, v); \ } -#define ATOMIC_FETCH_OP(op, func_op, I, c_type, prefix) \ -static __always_inline c_type atomic##prefix##_fetch_##op(atomic##prefix##_t *v) \ -{ \ - return atomic##prefix##_fetch_##func_op(I, v); \ +#define ATOMIC_FETCH_OP(op, func_op, I, c_type, prefix) \ +static __always_inline \ +c_type atomic##prefix##_fetch_##op##_relaxed(atomic##prefix##_t *v) \ +{ \ + return atomic##prefix##_fetch_##func_op##_relaxed(I, v); \ +} \ +static __always_inline \ +c_type atomic##prefix##_fetch_##op(atomic##prefix##_t *v) \ +{ \ + return atomic##prefix##_fetch_##func_op(I, v); \ } -#define ATOMIC_OP_RETURN(op, asm_op, c_op, I, c_type, prefix) \ -static __always_inline c_type atomic##prefix##_##op##_return(atomic##prefix##_t *v) \ -{ \ - return atomic##prefix##_fetch_##op(v) c_op I; \ +#define ATOMIC_OP_RETURN(op, asm_op, c_op, I, c_type, prefix) \ +static __always_inline \ +c_type atomic##prefix##_##op##_return_relaxed(atomic##prefix##_t *v) \ +{ \ + return atomic##prefix##_fetch_##op##_relaxed(v) c_op I; \ +} \ +static __always_inline \ +c_type atomic##prefix##_##op##_return(atomic##prefix##_t *v) \ +{ \ + return atomic##prefix##_fetch_##op(v) c_op I; \ } #ifdef CONFIG_GENERIC_ATOMIC64 -#define ATOMIC_OPS(op, asm_op, c_op, I) \ - ATOMIC_OP (op, asm_op, I, int, ) \ - ATOMIC_FETCH_OP (op, asm_op, I, int, ) \ +#define ATOMIC_OPS(op, asm_op, c_op, I) \ + ATOMIC_OP( op, asm_op, I, int, ) \ + ATOMIC_FETCH_OP( op, asm_op, I, int, ) \ ATOMIC_OP_RETURN(op, asm_op, c_op, I, int, ) #else -#define ATOMIC_OPS(op, asm_op, c_op, I) \ - ATOMIC_OP (op, asm_op, I, int, ) \ - ATOMIC_FETCH_OP (op, asm_op, I, int, ) \ - ATOMIC_OP_RETURN(op, asm_op, c_op, I, int, ) \ - ATOMIC_OP (op, asm_op, I, long, 64) \ - ATOMIC_FETCH_OP (op, asm_op, I, long, 64) \ +#define ATOMIC_OPS(op, asm_op, c_op, I) \ + ATOMIC_OP( op, asm_op, I, int, ) \ + ATOMIC_FETCH_OP( op, asm_op, I, int, ) \ + ATOMIC_OP_RETURN(op, asm_op, c_op, I, int, ) \ + ATOMIC_OP( op, asm_op, I, long, 64) \ + ATOMIC_FETCH_OP( op, asm_op, I, long, 64) \ ATOMIC_OP_RETURN(op, asm_op, c_op, I, long, 64) #endif ATOMIC_OPS(inc, add, +, 1) ATOMIC_OPS(dec, add, +, -1) +#define atomic_inc_return_relaxed atomic_inc_return_relaxed +#define atomic_dec_return_relaxed atomic_dec_return_relaxed +#define atomic_inc_return atomic_inc_return +#define atomic_dec_return atomic_dec_return + +#define atomic_fetch_inc_relaxed atomic_fetch_inc_relaxed +#define atomic_fetch_dec_relaxed atomic_fetch_dec_relaxed +#define atomic_fetch_inc atomic_fetch_inc +#define atomic_fetch_dec atomic_fetch_dec + +#ifndef CONFIG_GENERIC_ATOMIC64 +#define atomic64_inc_return_relaxed atomic64_inc_return_relaxed +#define atomic64_dec_return_relaxed atomic64_dec_return_relaxed +#define atomic64_inc_return atomic64_inc_return +#define atomic64_dec_return atomic64_dec_return + +#define atomic64_fetch_inc_relaxed atomic64_fetch_inc_relaxed +#define atomic64_fetch_dec_relaxed atomic64_fetch_dec_relaxed +#define atomic64_fetch_inc atomic64_fetch_inc +#define atomic64_fetch_dec atomic64_fetch_dec +#endif + #undef ATOMIC_OPS #undef ATOMIC_OP #undef ATOMIC_FETCH_OP #undef ATOMIC_OP_RETURN -#define ATOMIC_OP(op, func_op, comp_op, I, prefix) \ -static __always_inline bool atomic##prefix##_##op(atomic##prefix##_t *v) \ -{ \ - return atomic##prefix##_##func_op##_return(v) comp_op I; \ +#define ATOMIC_OP(op, func_op, comp_op, I, prefix) \ +static __always_inline \ +bool atomic##prefix##_##op(atomic##prefix##_t *v) \ +{ \ + return atomic##prefix##_##func_op##_return(v) comp_op I; \ } ATOMIC_OP(inc_and_test, inc, ==, 0, ) @@ -238,19 +331,19 @@ ATOMIC_OP(dec_and_test, dec, ==, 0, 64) #undef ATOMIC_OP -/* This is required to provide a barrier on success. */ +/* This is required to provide a full barrier on success. */ static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u) { int prev, rc; __asm__ __volatile__ ( - "0:\n\t" - "lr.w.aqrl %[p], %[c]\n\t" - "beq %[p], %[u], 1f\n\t" - "add %[rc], %[p], %[a]\n\t" - "sc.w.aqrl %[rc], %[rc], %[c]\n\t" - "bnez %[rc], 0b\n\t" - "1:" + "0: lr.w %[p], %[c]\n" + " beq %[p], %[u], 1f\n" + " add %[rc], %[p], %[a]\n" + " sc.w.rl %[rc], %[rc], %[c]\n" + " bnez %[rc], 0b\n" + " fence rw, rw\n" + "1:\n" : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter) : [a]"r" (a), [u]"r" (u) : "memory"); @@ -263,13 +356,13 @@ static __always_inline long __atomic64_add_unless(atomic64_t *v, long a, long u) long prev, rc; __asm__ __volatile__ ( - "0:\n\t" - "lr.d.aqrl %[p], %[c]\n\t" - "beq %[p], %[u], 1f\n\t" - "add %[rc], %[p], %[a]\n\t" - "sc.d.aqrl %[rc], %[rc], %[c]\n\t" - "bnez %[rc], 0b\n\t" - "1:" + "0: lr.d %[p], %[c]\n" + " beq %[p], %[u], 1f\n" + " add %[rc], %[p], %[a]\n" + " sc.d.rl %[rc], %[rc], %[c]\n" + " bnez %[rc], 0b\n" + " fence rw, rw\n" + "1:\n" : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter) : [a]"r" (a), [u]"r" (u) : "memory"); @@ -300,37 +393,63 @@ static __always_inline long atomic64_inc_not_zero(atomic64_t *v) /* * atomic_{cmp,}xchg is required to have exactly the same ordering semantics as - * {cmp,}xchg and the operations that return, so they need a barrier. - */ -/* - * FIXME: atomic_cmpxchg_{acquire,release,relaxed} are all implemented by - * assigning the same barrier to both the LR and SC operations, but that might - * not make any sense. We're waiting on a memory model specification to - * determine exactly what the right thing to do is here. + * {cmp,}xchg and the operations that return, so they need a full barrier. */ -#define ATOMIC_OP(c_t, prefix, c_or, size, asm_or) \ -static __always_inline c_t atomic##prefix##_cmpxchg##c_or(atomic##prefix##_t *v, c_t o, c_t n) \ -{ \ - return __cmpxchg(&(v->counter), o, n, size, asm_or, asm_or); \ -} \ -static __always_inline c_t atomic##prefix##_xchg##c_or(atomic##prefix##_t *v, c_t n) \ -{ \ - return __xchg(n, &(v->counter), size, asm_or); \ +#define ATOMIC_OP(c_t, prefix, size) \ +static __always_inline \ +c_t atomic##prefix##_xchg_relaxed(atomic##prefix##_t *v, c_t n) \ +{ \ + return __xchg_relaxed(&(v->counter), n, size); \ +} \ +static __always_inline \ +c_t atomic##prefix##_xchg_acquire(atomic##prefix##_t *v, c_t n) \ +{ \ + return __xchg_acquire(&(v->counter), n, size); \ +} \ +static __always_inline \ +c_t atomic##prefix##_xchg_release(atomic##prefix##_t *v, c_t n) \ +{ \ + return __xchg_release(&(v->counter), n, size); \ +} \ +static __always_inline \ +c_t atomic##prefix##_xchg(atomic##prefix##_t *v, c_t n) \ +{ \ + return __xchg(&(v->counter), n, size); \ +} \ +static __always_inline \ +c_t atomic##prefix##_cmpxchg_relaxed(atomic##prefix##_t *v, \ + c_t o, c_t n) \ +{ \ + return __cmpxchg_relaxed(&(v->counter), o, n, size); \ +} \ +static __always_inline \ +c_t atomic##prefix##_cmpxchg_acquire(atomic##prefix##_t *v, \ + c_t o, c_t n) \ +{ \ + return __cmpxchg_acquire(&(v->counter), o, n, size); \ +} \ +static __always_inline \ +c_t atomic##prefix##_cmpxchg_release(atomic##prefix##_t *v, \ + c_t o, c_t n) \ +{ \ + return __cmpxchg_release(&(v->counter), o, n, size); \ +} \ +static __always_inline \ +c_t atomic##prefix##_cmpxchg(atomic##prefix##_t *v, c_t o, c_t n) \ +{ \ + return __cmpxchg(&(v->counter), o, n, size); \ } #ifdef CONFIG_GENERIC_ATOMIC64 -#define ATOMIC_OPS(c_or, asm_or) \ - ATOMIC_OP( int, , c_or, 4, asm_or) +#define ATOMIC_OPS() \ + ATOMIC_OP( int, , 4) #else -#define ATOMIC_OPS(c_or, asm_or) \ - ATOMIC_OP( int, , c_or, 4, asm_or) \ - ATOMIC_OP(long, 64, c_or, 8, asm_or) +#define ATOMIC_OPS() \ + ATOMIC_OP( int, , 4) \ + ATOMIC_OP(long, 64, 8) #endif -ATOMIC_OPS( , .aqrl) -ATOMIC_OPS(_acquire, .aq) -ATOMIC_OPS(_release, .rl) -ATOMIC_OPS(_relaxed, ) +ATOMIC_OPS() #undef ATOMIC_OPS #undef ATOMIC_OP @@ -340,13 +459,13 @@ static __always_inline int atomic_sub_if_positive(atomic_t *v, int offset) int prev, rc; __asm__ __volatile__ ( - "0:\n\t" - "lr.w.aqrl %[p], %[c]\n\t" - "sub %[rc], %[p], %[o]\n\t" - "bltz %[rc], 1f\n\t" - "sc.w.aqrl %[rc], %[rc], %[c]\n\t" - "bnez %[rc], 0b\n\t" - "1:" + "0: lr.w %[p], %[c]\n" + " sub %[rc], %[p], %[o]\n" + " bltz %[rc], 1f\n" + " sc.w.rl %[rc], %[rc], %[c]\n" + " bnez %[rc], 0b\n" + " fence rw, rw\n" + "1:\n" : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter) : [o]"r" (offset) : "memory"); @@ -361,13 +480,13 @@ static __always_inline long atomic64_sub_if_positive(atomic64_t *v, int offset) long prev, rc; __asm__ __volatile__ ( - "0:\n\t" - "lr.d.aqrl %[p], %[c]\n\t" - "sub %[rc], %[p], %[o]\n\t" - "bltz %[rc], 1f\n\t" - "sc.d.aqrl %[rc], %[rc], %[c]\n\t" - "bnez %[rc], 0b\n\t" - "1:" + "0: lr.d %[p], %[c]\n" + " sub %[rc], %[p], %[o]\n" + " bltz %[rc], 1f\n" + " sc.d.rl %[rc], %[rc], %[c]\n" + " bnez %[rc], 0b\n" + " fence rw, rw\n" + "1:\n" : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter) : [o]"r" (offset) : "memory"); diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h index db249dbc7b976..c12833f7b6bd1 100644 --- a/arch/riscv/include/asm/cmpxchg.h +++ b/arch/riscv/include/asm/cmpxchg.h @@ -17,45 +17,153 @@ #include #include +#include -#define __xchg(new, ptr, size, asm_or) \ -({ \ - __typeof__(ptr) __ptr = (ptr); \ - __typeof__(new) __new = (new); \ - __typeof__(*(ptr)) __ret; \ - switch (size) { \ - case 4: \ - __asm__ __volatile__ ( \ - "amoswap.w" #asm_or " %0, %2, %1" \ - : "=r" (__ret), "+A" (*__ptr) \ - : "r" (__new) \ - : "memory"); \ - break; \ - case 8: \ - __asm__ __volatile__ ( \ - "amoswap.d" #asm_or " %0, %2, %1" \ - : "=r" (__ret), "+A" (*__ptr) \ - : "r" (__new) \ - : "memory"); \ - break; \ - default: \ - BUILD_BUG(); \ - } \ - __ret; \ -}) - -#define xchg(ptr, x) (__xchg((x), (ptr), sizeof(*(ptr)), .aqrl)) - -#define xchg32(ptr, x) \ -({ \ - BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ - xchg((ptr), (x)); \ -}) - -#define xchg64(ptr, x) \ -({ \ - BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ - xchg((ptr), (x)); \ +#define __xchg_relaxed(ptr, new, size) \ +({ \ + __typeof__(ptr) __ptr = (ptr); \ + __typeof__(new) __new = (new); \ + __typeof__(*(ptr)) __ret; \ + switch (size) { \ + case 4: \ + __asm__ __volatile__ ( \ + " amoswap.w %0, %2, %1\n" \ + : "=r" (__ret), "+A" (*__ptr) \ + : "r" (__new) \ + : "memory"); \ + break; \ + case 8: \ + __asm__ __volatile__ ( \ + " amoswap.d %0, %2, %1\n" \ + : "=r" (__ret), "+A" (*__ptr) \ + : "r" (__new) \ + : "memory"); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ + __ret; \ +}) + +#define xchg_relaxed(ptr, x) \ +({ \ + __typeof__(*(ptr)) _x_ = (x); \ + (__typeof__(*(ptr))) __xchg_relaxed((ptr), \ + _x_, sizeof(*(ptr))); \ +}) + +#define __xchg_acquire(ptr, new, size) \ +({ \ + __typeof__(ptr) __ptr = (ptr); \ + __typeof__(new) __new = (new); \ + __typeof__(*(ptr)) __ret; \ + switch (size) { \ + case 4: \ + __asm__ __volatile__ ( \ + " amoswap.w %0, %2, %1\n" \ + RISCV_ACQUIRE_BARRIER \ + : "=r" (__ret), "+A" (*__ptr) \ + : "r" (__new) \ + : "memory"); \ + break; \ + case 8: \ + __asm__ __volatile__ ( \ + " amoswap.d %0, %2, %1\n" \ + RISCV_ACQUIRE_BARRIER \ + : "=r" (__ret), "+A" (*__ptr) \ + : "r" (__new) \ + : "memory"); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ + __ret; \ +}) + +#define xchg_acquire(ptr, x) \ +({ \ + __typeof__(*(ptr)) _x_ = (x); \ + (__typeof__(*(ptr))) __xchg_acquire((ptr), \ + _x_, sizeof(*(ptr))); \ +}) + +#define __xchg_release(ptr, new, size) \ +({ \ + __typeof__(ptr) __ptr = (ptr); \ + __typeof__(new) __new = (new); \ + __typeof__(*(ptr)) __ret; \ + switch (size) { \ + case 4: \ + __asm__ __volatile__ ( \ + RISCV_RELEASE_BARRIER \ + " amoswap.w %0, %2, %1\n" \ + : "=r" (__ret), "+A" (*__ptr) \ + : "r" (__new) \ + : "memory"); \ + break; \ + case 8: \ + __asm__ __volatile__ ( \ + RISCV_RELEASE_BARRIER \ + " amoswap.d %0, %2, %1\n" \ + : "=r" (__ret), "+A" (*__ptr) \ + : "r" (__new) \ + : "memory"); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ + __ret; \ +}) + +#define xchg_release(ptr, x) \ +({ \ + __typeof__(*(ptr)) _x_ = (x); \ + (__typeof__(*(ptr))) __xchg_release((ptr), \ + _x_, sizeof(*(ptr))); \ +}) + +#define __xchg(ptr, new, size) \ +({ \ + __typeof__(ptr) __ptr = (ptr); \ + __typeof__(new) __new = (new); \ + __typeof__(*(ptr)) __ret; \ + switch (size) { \ + case 4: \ + __asm__ __volatile__ ( \ + " amoswap.w.aqrl %0, %2, %1\n" \ + : "=r" (__ret), "+A" (*__ptr) \ + : "r" (__new) \ + : "memory"); \ + break; \ + case 8: \ + __asm__ __volatile__ ( \ + " amoswap.d.aqrl %0, %2, %1\n" \ + : "=r" (__ret), "+A" (*__ptr) \ + : "r" (__new) \ + : "memory"); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ + __ret; \ +}) + +#define xchg(ptr, x) \ +({ \ + __typeof__(*(ptr)) _x_ = (x); \ + (__typeof__(*(ptr))) __xchg((ptr), _x_, sizeof(*(ptr))); \ +}) + +#define xchg32(ptr, x) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ + xchg((ptr), (x)); \ +}) + +#define xchg64(ptr, x) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ + xchg((ptr), (x)); \ }) /* @@ -63,7 +171,51 @@ * store NEW in MEM. Return the initial value in MEM. Success is * indicated by comparing RETURN with OLD. */ -#define __cmpxchg(ptr, old, new, size, lrb, scb) \ +#define __cmpxchg_relaxed(ptr, old, new, size) \ +({ \ + __typeof__(ptr) __ptr = (ptr); \ + __typeof__(*(ptr)) __old = (old); \ + __typeof__(*(ptr)) __new = (new); \ + __typeof__(*(ptr)) __ret; \ + register unsigned int __rc; \ + switch (size) { \ + case 4: \ + __asm__ __volatile__ ( \ + "0: lr.w %0, %2\n" \ + " bne %0, %z3, 1f\n" \ + " sc.w %1, %z4, %2\n" \ + " bnez %1, 0b\n" \ + "1:\n" \ + : "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \ + : "rJ" (__old), "rJ" (__new) \ + : "memory"); \ + break; \ + case 8: \ + __asm__ __volatile__ ( \ + "0: lr.d %0, %2\n" \ + " bne %0, %z3, 1f\n" \ + " sc.d %1, %z4, %2\n" \ + " bnez %1, 0b\n" \ + "1:\n" \ + : "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \ + : "rJ" (__old), "rJ" (__new) \ + : "memory"); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ + __ret; \ +}) + +#define cmpxchg_relaxed(ptr, o, n) \ +({ \ + __typeof__(*(ptr)) _o_ = (o); \ + __typeof__(*(ptr)) _n_ = (n); \ + (__typeof__(*(ptr))) __cmpxchg_relaxed((ptr), \ + _o_, _n_, sizeof(*(ptr))); \ +}) + +#define __cmpxchg_acquire(ptr, old, new, size) \ ({ \ __typeof__(ptr) __ptr = (ptr); \ __typeof__(*(ptr)) __old = (old); \ @@ -73,24 +225,24 @@ switch (size) { \ case 4: \ __asm__ __volatile__ ( \ - "0:" \ - "lr.w" #scb " %0, %2\n" \ - "bne %0, %z3, 1f\n" \ - "sc.w" #lrb " %1, %z4, %2\n" \ - "bnez %1, 0b\n" \ - "1:" \ + "0: lr.w %0, %2\n" \ + " bne %0, %z3, 1f\n" \ + " sc.w %1, %z4, %2\n" \ + " bnez %1, 0b\n" \ + RISCV_ACQUIRE_BARRIER \ + "1:\n" \ : "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \ : "rJ" (__old), "rJ" (__new) \ : "memory"); \ break; \ case 8: \ __asm__ __volatile__ ( \ - "0:" \ - "lr.d" #scb " %0, %2\n" \ - "bne %0, %z3, 1f\n" \ - "sc.d" #lrb " %1, %z4, %2\n" \ - "bnez %1, 0b\n" \ - "1:" \ + "0: lr.d %0, %2\n" \ + " bne %0, %z3, 1f\n" \ + " sc.d %1, %z4, %2\n" \ + " bnez %1, 0b\n" \ + RISCV_ACQUIRE_BARRIER \ + "1:\n" \ : "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \ : "rJ" (__old), "rJ" (__new) \ : "memory"); \ @@ -101,34 +253,131 @@ __ret; \ }) -#define cmpxchg(ptr, o, n) \ - (__cmpxchg((ptr), (o), (n), sizeof(*(ptr)), .aqrl, .aqrl)) +#define cmpxchg_acquire(ptr, o, n) \ +({ \ + __typeof__(*(ptr)) _o_ = (o); \ + __typeof__(*(ptr)) _n_ = (n); \ + (__typeof__(*(ptr))) __cmpxchg_acquire((ptr), \ + _o_, _n_, sizeof(*(ptr))); \ +}) -#define cmpxchg_local(ptr, o, n) \ - (__cmpxchg((ptr), (o), (n), sizeof(*(ptr)), , )) +#define __cmpxchg_release(ptr, old, new, size) \ +({ \ + __typeof__(ptr) __ptr = (ptr); \ + __typeof__(*(ptr)) __old = (old); \ + __typeof__(*(ptr)) __new = (new); \ + __typeof__(*(ptr)) __ret; \ + register unsigned int __rc; \ + switch (size) { \ + case 4: \ + __asm__ __volatile__ ( \ + RISCV_RELEASE_BARRIER \ + "0: lr.w %0, %2\n" \ + " bne %0, %z3, 1f\n" \ + " sc.w %1, %z4, %2\n" \ + " bnez %1, 0b\n" \ + "1:\n" \ + : "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \ + : "rJ" (__old), "rJ" (__new) \ + : "memory"); \ + break; \ + case 8: \ + __asm__ __volatile__ ( \ + RISCV_RELEASE_BARRIER \ + "0: lr.d %0, %2\n" \ + " bne %0, %z3, 1f\n" \ + " sc.d %1, %z4, %2\n" \ + " bnez %1, 0b\n" \ + "1:\n" \ + : "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \ + : "rJ" (__old), "rJ" (__new) \ + : "memory"); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ + __ret; \ +}) + +#define cmpxchg_release(ptr, o, n) \ +({ \ + __typeof__(*(ptr)) _o_ = (o); \ + __typeof__(*(ptr)) _n_ = (n); \ + (__typeof__(*(ptr))) __cmpxchg_release((ptr), \ + _o_, _n_, sizeof(*(ptr))); \ +}) + +#define __cmpxchg(ptr, old, new, size) \ +({ \ + __typeof__(ptr) __ptr = (ptr); \ + __typeof__(*(ptr)) __old = (old); \ + __typeof__(*(ptr)) __new = (new); \ + __typeof__(*(ptr)) __ret; \ + register unsigned int __rc; \ + switch (size) { \ + case 4: \ + __asm__ __volatile__ ( \ + "0: lr.w %0, %2\n" \ + " bne %0, %z3, 1f\n" \ + " sc.w.rl %1, %z4, %2\n" \ + " bnez %1, 0b\n" \ + " fence rw, rw\n" \ + "1:\n" \ + : "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \ + : "rJ" (__old), "rJ" (__new) \ + : "memory"); \ + break; \ + case 8: \ + __asm__ __volatile__ ( \ + "0: lr.d %0, %2\n" \ + " bne %0, %z3, 1f\n" \ + " sc.d.rl %1, %z4, %2\n" \ + " bnez %1, 0b\n" \ + " fence rw, rw\n" \ + "1:\n" \ + : "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \ + : "rJ" (__old), "rJ" (__new) \ + : "memory"); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ + __ret; \ +}) -#define cmpxchg32(ptr, o, n) \ -({ \ - BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ - cmpxchg((ptr), (o), (n)); \ +#define cmpxchg(ptr, o, n) \ +({ \ + __typeof__(*(ptr)) _o_ = (o); \ + __typeof__(*(ptr)) _n_ = (n); \ + (__typeof__(*(ptr))) __cmpxchg((ptr), \ + _o_, _n_, sizeof(*(ptr))); \ }) -#define cmpxchg32_local(ptr, o, n) \ -({ \ - BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ - cmpxchg_local((ptr), (o), (n)); \ +#define cmpxchg_local(ptr, o, n) \ + (__cmpxchg_relaxed((ptr), (o), (n), sizeof(*(ptr)))) + +#define cmpxchg32(ptr, o, n) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ + cmpxchg((ptr), (o), (n)); \ }) -#define cmpxchg64(ptr, o, n) \ -({ \ - BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ - cmpxchg((ptr), (o), (n)); \ +#define cmpxchg32_local(ptr, o, n) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ + cmpxchg_relaxed((ptr), (o), (n)) \ }) -#define cmpxchg64_local(ptr, o, n) \ -({ \ - BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ - cmpxchg_local((ptr), (o), (n)); \ +#define cmpxchg64(ptr, o, n) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ + cmpxchg((ptr), (o), (n)); \ +}) + +#define cmpxchg64_local(ptr, o, n) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ + cmpxchg_relaxed((ptr), (o), (n)); \ }) #endif /* _ASM_RISCV_CMPXCHG_H */ -- 2.7.4