From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751884AbbH1CtF (ORCPT ); Thu, 27 Aug 2015 22:49:05 -0400 Received: from mail-io0-f178.google.com ([209.85.223.178]:33592 "EHLO mail-io0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751666AbbH1CtC (ORCPT ); Thu, 27 Aug 2015 22:49:02 -0400 From: Boqun Feng To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Peter Zijlstra , Ingo Molnar , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Thomas Gleixner , Will Deacon , "Paul E. McKenney" , Waiman Long , Boqun Feng Subject: [RFC 4/5] powerpc: atomic: implement xchg_* and atomic{,64}_xchg_* variants Date: Fri, 28 Aug 2015 10:48:18 +0800 Message-Id: <1440730099-29133-5-git-send-email-boqun.feng@gmail.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1440730099-29133-1-git-send-email-boqun.feng@gmail.com> References: <1440730099-29133-1-git-send-email-boqun.feng@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Implement xchg_relaxed and define atomic{,64}_xchg_* as xchg_relaxed, based on these _relaxed variants, release/acquire variants can be built. Note that xchg_relaxed and atomic_{,64}_xchg_relaxed are not compiler barriers. Signed-off-by: Boqun Feng --- arch/powerpc/include/asm/atomic.h | 2 ++ arch/powerpc/include/asm/cmpxchg.h | 64 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 66 insertions(+) diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h index 806ce50..4965dcf 100644 --- a/arch/powerpc/include/asm/atomic.h +++ b/arch/powerpc/include/asm/atomic.h @@ -193,6 +193,7 @@ static __inline__ int atomic_dec_return(atomic_t *v) #define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n))) #define atomic_xchg(v, new) (xchg(&((v)->counter), new)) +#define atomic_xchg_relaxed(v, new) xchg_relaxed(&((v)->counter), (new)) /** * __atomic_add_unless - add unless the number is a given value @@ -461,6 +462,7 @@ static __inline__ long atomic64_dec_if_positive(atomic64_t *v) #define atomic64_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n))) #define atomic64_xchg(v, new) (xchg(&((v)->counter), new)) +#define atomic64_xchg_relaxed(v, new) xchg_relaxed(&((v)->counter), (new)) /** * atomic64_add_unless - add unless the number is a given value diff --git a/arch/powerpc/include/asm/cmpxchg.h b/arch/powerpc/include/asm/cmpxchg.h index ad6263c..66374f4 100644 --- a/arch/powerpc/include/asm/cmpxchg.h +++ b/arch/powerpc/include/asm/cmpxchg.h @@ -54,6 +54,32 @@ __xchg_u32_local(volatile void *p, unsigned long val) return prev; } +/* + * Atomic exchange relaxed + * + * Changes the memory location '*p' to be val and returns + * the previous value stored there. + * + * Note that this is not a compiler barrier, there is no order + * guarantee around. + */ +static __always_inline unsigned long +__xchg_u32_relaxed(u32 *p, unsigned long val) +{ + unsigned long prev; + + __asm__ __volatile__( +"1: lwarx %0,0,%2\n" + PPC405_ERR77(0, %2) +" stwcx. %3,0,%2\n" +" bne- 1b" + : "=&r" (prev), "+m" (*p) + : "r" (p), "r" (val) + : "cc"); + + return prev; +} + #ifdef CONFIG_PPC64 static __always_inline unsigned long __xchg_u64(volatile void *p, unsigned long val) @@ -90,6 +116,23 @@ __xchg_u64_local(volatile void *p, unsigned long val) return prev; } + +static __always_inline unsigned long +__xchg_u64_relaxed(u64 *p, unsigned long val) +{ + unsigned long prev; + + __asm__ __volatile__( +"1: ldarx %0,0,%2\n" + PPC405_ERR77(0, %2) +" stdcx. %3,0,%2\n" +" bne- 1b" + : "=&r" (prev), "+m" (*p) + : "r" (p), "r" (val) + : "cc"); + + return prev; +} #endif /* @@ -127,6 +170,21 @@ __xchg_local(volatile void *ptr, unsigned long x, unsigned int size) __xchg_called_with_bad_pointer(); return x; } + +static __always_inline unsigned long +__xchg_relaxed(void *ptr, unsigned long x, unsigned int size) +{ + switch (size) { + case 4: + return __xchg_u32_relaxed(ptr, x); +#ifdef CONFIG_PPC64 + case 8: + return __xchg_u64_relaxed(ptr, x); +#endif + } + __xchg_called_with_bad_pointer(); + return x; +} #define xchg(ptr,x) \ ({ \ __typeof__(*(ptr)) _x_ = (x); \ @@ -140,6 +198,12 @@ __xchg_local(volatile void *ptr, unsigned long x, unsigned int size) (unsigned long)_x_, sizeof(*(ptr))); \ }) +#define xchg_relaxed(ptr, x) \ +({ \ + __typeof__(*(ptr)) _x_ = (x); \ + (__typeof__(*(ptr))) __xchg_relaxed((ptr), \ + (unsigned long)_x_, sizeof(*(ptr))); \ +}) /* * Compare and exchange - if *p == old, set it to new, * and return the old value of *p. -- 2.5.0