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Message-ID: <20180309183644.GA3092@andrea>
Date: Fri, 9 Mar 2018 19:36:44 +0100
From: Andrea Parri <parri.andrea@...il.com>
To: Palmer Dabbelt <palmer@...ive.com>
Cc: albert@...ive.com, Daniel Lustig <dlustig@...dia.com>,
stern@...land.harvard.edu, Will Deacon <will.deacon@....com>,
peterz@...radead.org, boqun.feng@...il.com, npiggin@...il.com,
dhowells@...hat.com, j.alglave@....ac.uk, luc.maranget@...ia.fr,
paulmck@...ux.vnet.ibm.com, akiyks@...il.com, mingo@...nel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] riscv/atomic: Strengthen implementations with
fences
On Fri, Mar 09, 2018 at 09:56:21AM -0800, Palmer Dabbelt wrote:
> On Fri, 09 Mar 2018 04:13:40 PST (-0800), parri.andrea@...il.com wrote:
> >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 <dlustig@...dia.com>
> >Signed-off-by: Andrea Parri <parri.andrea@...il.com>
> >Cc: Palmer Dabbelt <palmer@...ive.com>
> >Cc: Albert Ou <albert@...ive.com>
> >Cc: Daniel Lustig <dlustig@...dia.com>
> >Cc: Alan Stern <stern@...land.harvard.edu>
> >Cc: Will Deacon <will.deacon@....com>
> >Cc: Peter Zijlstra <peterz@...radead.org>
> >Cc: Boqun Feng <boqun.feng@...il.com>
> >Cc: Nicholas Piggin <npiggin@...il.com>
> >Cc: David Howells <dhowells@...hat.com>
> >Cc: Jade Alglave <j.alglave@....ac.uk>
> >Cc: Luc Maranget <luc.maranget@...ia.fr>
> >Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
> >Cc: Akira Yokosawa <akiyks@...il.com>
> >Cc: Ingo Molnar <mingo@...nel.org>
> >Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> >Cc: linux-riscv@...ts.infradead.org
> >Cc: linux-kernel@...r.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 <asm/barrier.h>
> >
> > #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"); \
> >+} \
>
> Just to be sure: this is just a whitespace change, right?
This belongs to the "few style fixes" (in the specific, 80-chars lines)
mentioned in the cover letter; I could not resist ;-), but I'll remove
them in v3 if you like so.
>
> > #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)
>
> Sorry, I must be missing something, but how do the acquire and release atomics
> get generated with this new code?
This proposal relies on the generic definition,
include/linux/atomic.h ,
and on the
__atomic_op_acquire()
__atomic_op_release()
above to build the acquire/release atomics (except for the xchg,cmpxchg,
where the ACQUIRE_BARRIER is inserted conditionally/on success).
Andrea
>
> >+
> >+#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 <linux/bug.h>
> >
> > #include <asm/barrier.h>
> >+#include <asm/fence.h>
> >
> >-#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 */
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