[PATCH v3 5/6] powerpc: atomic: Implement xchg_* and atomic{,64}_xchg_* variants

Boqun Feng
2015-10-12T14:15:53Z

Implement xchg_relaxed and atomic{,64}_xchg_relaxed, based on these
_relaxed variants, release/acquire variants and fully ordered versions
can be built.

Note that xchg_relaxed and atomic_{,64}_xchg_relaxed are not compiler
barriers.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
arch/powerpc/include/asm/atomic.h | 2 ++
arch/powerpc/include/asm/cmpxchg.h | 69 +++++++++++++++++---------------------
2 files changed, 32 insertions(+), 39 deletions(-)

diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h
index 3143af9..8869fb3 100644
--- a/arch/powerpc/include/asm/atomic.h
+++ b/arch/powerpc/include/asm/atomic.h
@@ -192,6 +192,7 @@ static __inline__ int atomic_dec_return_relaxed(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
@@ -459,6 +460,7 @@ 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 d1a8d93..17c7e14 100644
--- a/arch/powerpc/include/asm/cmpxchg.h
+++ b/arch/powerpc/include/asm/cmpxchg.h
@@ -9,21 +9,20 @@
/*
* Atomic exchange
*
- * Changes the memory location '*ptr' to be val and returns
+ * Changes the memory location '*p' to be val and returns
* the previous value stored there.
*/
+
static __always_inline unsigned long
-__xchg_u32(volatile void *p, unsigned long val)
+__xchg_u32_local(volatile void *p, unsigned long val)
{
unsigned long prev;

__asm__ __volatile__(
- PPC_ATOMIC_ENTRY_BARRIER
"1: lwarx %0,0,%2 \n"
PPC405_ERR77(0,%2)
" stwcx. %3,0,%2 \n\
bne- 1b"
- PPC_ATOMIC_EXIT_BARRIER
: "=&r" (prev), "+m" (*(volatile unsigned int *)p)
: "r" (p), "r" (val)
: "cc", "memory");
@@ -31,42 +30,34 @@ __xchg_u32(volatile void *p, unsigned long val)
return prev;
}

-/*
- * Atomic exchange
- *
- * Changes the memory location '*ptr' to be val and returns
- * the previous value stored there.
- */
static __always_inline unsigned long
-__xchg_u32_local(volatile void *p, unsigned long val)
+__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" (*(volatile unsigned int *)p)
+"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", "memory");
+ : "cc");

return prev;
}

#ifdef CONFIG_PPC64
static __always_inline unsigned long
-__xchg_u64(volatile void *p, unsigned long val)
+__xchg_u64_local(volatile void *p, unsigned long val)
{
unsigned long prev;

__asm__ __volatile__(
- PPC_ATOMIC_ENTRY_BARRIER
"1: ldarx %0,0,%2 \n"
PPC405_ERR77(0,%2)
" stdcx. %3,0,%2 \n\
bne- 1b"
- PPC_ATOMIC_EXIT_BARRIER
: "=&r" (prev), "+m" (*(volatile unsigned long *)p)
: "r" (p), "r" (val)
: "cc", "memory");
@@ -75,18 +66,18 @@ __xchg_u64(volatile void *p, unsigned long val)
}

static __always_inline unsigned long
-__xchg_u64_local(volatile void *p, unsigned long val)
+__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" (*(volatile unsigned long *)p)
+"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", "memory");
+ : "cc");

return prev;
}
@@ -99,14 +90,14 @@ __xchg_u64_local(volatile void *p, unsigned long val)
extern void __xchg_called_with_bad_pointer(void);

static __always_inline unsigned long
-__xchg(volatile void *ptr, unsigned long x, unsigned int size)
+__xchg_local(volatile void *ptr, unsigned long x, unsigned int size)
{
switch (size) {
case 4:
- return __xchg_u32(ptr, x);
+ return __xchg_u32_local(ptr, x);
#ifdef CONFIG_PPC64
case 8:
- return __xchg_u64(ptr, x);
+ return __xchg_u64_local(ptr, x);
#endif
}
__xchg_called_with_bad_pointer();
@@ -114,25 +105,19 @@ __xchg(volatile void *ptr, unsigned long x, unsigned int size)
}

static __always_inline unsigned long
-__xchg_local(volatile void *ptr, unsigned long x, unsigned int size)
+__xchg_relaxed(void *ptr, unsigned long x, unsigned int size)
{
switch (size) {
case 4:
- return __xchg_u32_local(ptr, x);
+ return __xchg_u32_relaxed(ptr, x);
#ifdef CONFIG_PPC64
case 8:
- return __xchg_u64_local(ptr, x);
+ return __xchg_u64_relaxed(ptr, x);
#endif
}
__xchg_called_with_bad_pointer();
return x;
}
-#define xchg(ptr,x) \
- ({ \
- __typeof__(*(ptr)) _x_ = (x); \
- (__typeof__(*(ptr))) __xchg((ptr), (unsigned long)_x_, sizeof(*(ptr))); \
- })
-
#define xchg_local(ptr,x) \
({ \
__typeof__(*(ptr)) _x_ = (x); \
@@ -140,6 +125,12 @@ __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.
--
2.5.3