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Message-Id: <1440730099-29133-6-git-send-email-boqun.feng@gmail.com>
Date: Fri, 28 Aug 2015 10:48:19 +0800
From: Boqun Feng <boqun.feng@...il.com>
To: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>,
Thomas Gleixner <tglx@...utronix.de>,
Will Deacon <will.deacon@....com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Waiman Long <waiman.long@...com>,
Boqun Feng <boqun.feng@...il.com>
Subject: [RFC 5/5] powerpc: atomic: implement cmpxchg{,64}_* and atomic{,64}_cmpxchg_* variants
Unlike other atomic operation variants, cmpxchg{,64}_acquire and
atomic{,64}_cmpxchg_acquire don't have acquire semantics if the cmp part
fails, so we need to implement these using assembly.
Note cmpxchg{,64}_relaxed and atomic{,64}_cmpxchg_relaxed are not
compiler barriers.
Signed-off-by: Boqun Feng <boqun.feng@...il.com>
---
arch/powerpc/include/asm/atomic.h | 10 +++
arch/powerpc/include/asm/cmpxchg.h | 141 ++++++++++++++++++++++++++++++++++++-
2 files changed, 150 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h
index 4965dcf..ef8d062 100644
--- a/arch/powerpc/include/asm/atomic.h
+++ b/arch/powerpc/include/asm/atomic.h
@@ -192,6 +192,11 @@ static __inline__ int atomic_dec_return(atomic_t *v)
}
#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
+#define atomic_cmpxchg_relaxed(v, o, n) \
+ cmpxchg_relaxed(&((v)->counter), (o), (n))
+#define atomic_cmpxchg_acquire(v, o, n) \
+ cmpxchg_acquire(&((v)->counter), (o), (n))
+
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
#define atomic_xchg_relaxed(v, new) xchg_relaxed(&((v)->counter), (new))
@@ -461,6 +466,11 @@ static __inline__ long atomic64_dec_if_positive(atomic64_t *v)
}
#define atomic64_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
+#define atomic64_cmpxchg_relaxed(v, o, n) \
+ cmpxchg_relaxed(&((v)->counter), (o), (n))
+#define atomic64_cmpxchg_acquire(v, o, n) \
+ cmpxchg_acquire(&((v)->counter), (o), (n))
+
#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
#define atomic64_xchg_relaxed(v, new) xchg_relaxed(&((v)->counter), (new))
diff --git a/arch/powerpc/include/asm/cmpxchg.h b/arch/powerpc/include/asm/cmpxchg.h
index 66374f4..f40f295 100644
--- a/arch/powerpc/include/asm/cmpxchg.h
+++ b/arch/powerpc/include/asm/cmpxchg.h
@@ -254,6 +254,48 @@ __cmpxchg_u32_local(volatile unsigned int *p, unsigned long old,
return prev;
}
+static __always_inline unsigned long
+__cmpxchg_u32_relaxed(u32 *p, unsigned long old, unsigned long new)
+{
+ unsigned long prev;
+
+ __asm__ __volatile__ (
+"1: lwarx %0,0,%2 # __cmpxchg_u32_relaxed\n"
+" cmpw 0,%0,%3\n"
+" bne- 2f\n"
+ PPC405_ERR77(0, %2)
+" stwcx. %4,0,%2\n"
+" bne- 1b\n"
+"2:"
+ : "=&r" (prev), "+m" (*p)
+ : "r" (p), "r" (old), "r" (new)
+ : "cc");
+
+ return prev;
+}
+
+static __always_inline unsigned long
+__cmpxchg_u32_acquire(u32 *p, unsigned long old, unsigned long new)
+{
+ unsigned long prev;
+
+ __asm__ __volatile__ (
+"1: lwarx %0,0,%2 # __cmpxchg_u32_acquire\n"
+" cmpw 0,%0,%3\n"
+" bne- 2f\n"
+ PPC405_ERR77(0, %2)
+" stwcx. %4,0,%2\n"
+" bne- 1b\n"
+ PPC_ACQUIRE_BARRIER
+ "\n"
+"2:"
+ : "=&r" (prev), "+m" (*p)
+ : "r" (p), "r" (old), "r" (new)
+ : "cc", "memory");
+
+ return prev;
+}
+
#ifdef CONFIG_PPC64
static __always_inline unsigned long
__cmpxchg_u64(volatile unsigned long *p, unsigned long old, unsigned long new)
@@ -297,6 +339,46 @@ __cmpxchg_u64_local(volatile unsigned long *p, unsigned long old,
return prev;
}
+
+static __always_inline unsigned long
+__cmpxchg_u64_relaxed(u64 *p, unsigned long old, unsigned long new)
+{
+ unsigned long prev;
+
+ __asm__ __volatile__ (
+"1: ldarx %0,0,%2 # __cmpxchg_u64_relaxed\n"
+" cmpd 0,%0,%3\n"
+" bne- 2f\n"
+" stdcx. %4,0,%2\n"
+" bne- 1b\n"
+"2:"
+ : "=&r" (prev), "+m" (*p)
+ : "r" (p), "r" (old), "r" (new)
+ : "cc");
+
+ return prev;
+}
+
+static __always_inline unsigned long
+__cmpxchg_u64_acquire(u64 *p, unsigned long old, unsigned long new)
+{
+ unsigned long prev;
+
+ __asm__ __volatile__ (
+"1: ldarx %0,0,%2 # __cmpxchg_u64_acquire\n"
+" cmpd 0,%0,%3\n"
+" bne- 2f\n"
+" stdcx. %4,0,%2\n"
+" bne- 1b\n"
+ PPC_ACQUIRE_BARRIER
+ "\n"
+"2:"
+ : "=&r" (prev), "+m" (*p)
+ : "r" (p), "r" (old), "r" (new)
+ : "cc", "memory");
+
+ return prev;
+}
#endif
/* This function doesn't exist, so you'll get a linker error
@@ -335,6 +417,37 @@ __cmpxchg_local(volatile void *ptr, unsigned long old, unsigned long new,
return old;
}
+static __always_inline unsigned long
+__cmpxchg_relaxed(void *ptr, unsigned long old, unsigned long new,
+ unsigned int size)
+{
+ switch (size) {
+ case 4:
+ return __cmpxchg_u32_relaxed(ptr, old, new);
+#ifdef CONFIG_PPC64
+ case 8:
+ return __cmpxchg_u64_relaxed(ptr, old, new);
+#endif
+ }
+ __cmpxchg_called_with_bad_pointer();
+ return old;
+}
+
+static __always_inline unsigned long
+__cmpxchg_acquire(void *ptr, unsigned long old, unsigned long new,
+ unsigned int size)
+{
+ switch (size) {
+ case 4:
+ return __cmpxchg_u32_acquire(ptr, old, new);
+#ifdef CONFIG_PPC64
+ case 8:
+ return __cmpxchg_u64_acquire(ptr, old, new);
+#endif
+ }
+ __cmpxchg_called_with_bad_pointer();
+ return old;
+}
#define cmpxchg(ptr, o, n) \
({ \
__typeof__(*(ptr)) _o_ = (o); \
@@ -352,6 +465,23 @@ __cmpxchg_local(volatile void *ptr, unsigned long old, unsigned long new,
(unsigned long)_n_, sizeof(*(ptr))); \
})
+#define cmpxchg_relaxed(ptr, o, n) \
+({ \
+ __typeof__(*(ptr)) _o_ = (o); \
+ __typeof__(*(ptr)) _n_ = (n); \
+ (__typeof__(*(ptr))) __cmpxchg_relaxed((ptr), \
+ (unsigned long)_o_, (unsigned long)_n_, \
+ sizeof(*(ptr))); \
+})
+
+#define cmpxchg_acquire(ptr, o, n) \
+({ \
+ __typeof__(*(ptr)) _o_ = (o); \
+ __typeof__(*(ptr)) _n_ = (n); \
+ (__typeof__(*(ptr))) __cmpxchg_acquire((ptr), \
+ (unsigned long)_o_, (unsigned long)_n_, \
+ sizeof(*(ptr))); \
+})
#ifdef CONFIG_PPC64
#define cmpxchg64(ptr, o, n) \
({ \
@@ -363,7 +493,16 @@ __cmpxchg_local(volatile void *ptr, unsigned long old, unsigned long new,
BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
cmpxchg_local((ptr), (o), (n)); \
})
-#define cmpxchg64_relaxed cmpxchg64_local
+#define cmpxchg64_relaxed(ptr, o, n) \
+({ \
+ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
+ cmpxchg_relaxed((ptr), (o), (n)); \
+})
+#define cmpxchg64_acquire(ptr, o, n) \
+({ \
+ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
+ cmpxchg_acquire((ptr), (o), (n)); \
+})
#else
#include <asm-generic/cmpxchg-local.h>
#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
--
2.5.0
--
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