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Clarify what we are doing in r234583 a little better: eieio and isync do

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not provide general barriers, but only barriers in the context of the
atomic sequences here. As such, make them private and keep the global
*mb() routines using a variant of sync.
This commit is contained in:
Nathan Whitehorn 2012-04-22 21:11:01 +00:00
parent 83ae3d5531
commit a6349a998d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=234584
1 changed files with 23 additions and 15 deletions
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38
sys/powerpc/include/atomic.h
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@ -37,13 +37,21 @@
#endif
/* NOTE: lwsync is equivalent to sync on systems without lwsync */
#define mb() __asm __volatile("lwsync" : : : "memory")
#define mb() __asm __volatile("lwsync" : : : "memory")
#define wmb() __asm __volatile("lwsync" : : : "memory")
#define rmb() __asm __volatile("lwsync" : : : "memory")
/*
* The __ATOMIC_XMB() macros provide memory barriers only in conjunction
* with the atomic lXarx/stXcx. sequences below. See Appendix B.2 of Book II
* of the architecture manual.
*/
#ifdef __powerpc64__
#define wmb() __asm __volatile("lwsync" : : : "memory")
#define rmb() __asm __volatile("lwsync" : : : "memory")
#define __ATOMIC_WMB() __asm __volatile("lwsync" : : : "memory")
#define __ATOMIC_RMB() __asm __volatile("lwsync" : : : "memory")
#else
#define wmb() __asm __volatile("eieio" : : : "memory")
#define rmb() __asm __volatile("isync" : : : "memory")
#define __ATOMIC_WMB() __asm __volatile("eieio" : : : "memory")
#define __ATOMIC_RMB() __asm __volatile("isync" : : : "memory")
#endif
/*
@ -97,13 +105,13 @@
atomic_add_acq_##type(volatile u_##type *p, u_##type v) { \
u_##type t; \
__atomic_add_##type(p, v, t); \
rmb(); \
__ATOMIC_RMB(); \
} \
\
static __inline void \
atomic_add_rel_##type(volatile u_##type *p, u_##type v) { \
u_##type t; \
wmb(); \
__ATOMIC_WMB(); \
__atomic_add_##type(p, v, t); \
} \
/* _ATOMIC_ADD */
@ -183,13 +191,13 @@ _ATOMIC_ADD(long)
atomic_clear_acq_##type(volatile u_##type *p, u_##type v) { \
u_##type t; \
__atomic_clear_##type(p, v, t); \
rmb(); \
__ATOMIC_RMB(); \
} \
\
static __inline void \
atomic_clear_rel_##type(volatile u_##type *p, u_##type v) { \
u_##type t; \
wmb(); \
__ATOMIC_WMB(); \
__atomic_clear_##type(p, v, t); \
} \
/* _ATOMIC_CLEAR */
@ -285,13 +293,13 @@ _ATOMIC_CLEAR(long)
atomic_set_acq_##type(volatile u_##type *p, u_##type v) { \
u_##type t; \
__atomic_set_##type(p, v, t); \
rmb(); \
__ATOMIC_RMB(); \
} \
\
static __inline void \
atomic_set_rel_##type(volatile u_##type *p, u_##type v) { \
u_##type t; \
wmb(); \
__ATOMIC_WMB(); \
__atomic_set_##type(p, v, t); \
} \
/* _ATOMIC_SET */
@ -371,13 +379,13 @@ _ATOMIC_SET(long)
atomic_subtract_acq_##type(volatile u_##type *p, u_##type v) { \
u_##type t; \
__atomic_subtract_##type(p, v, t); \
rmb(); \
__ATOMIC_RMB(); \
} \
\
static __inline void \
atomic_subtract_rel_##type(volatile u_##type *p, u_##type v) { \
u_##type t; \
wmb(); \
__ATOMIC_WMB(); \
__atomic_subtract_##type(p, v, t); \
} \
/* _ATOMIC_SUBTRACT */
@ -601,7 +609,7 @@ atomic_cmpset_acq_int(volatile u_int *p, u_int cmpval, u_int newval)
int retval;
retval = atomic_cmpset_int(p, cmpval, newval);
rmb();
__ATOMIC_RMB();
return (retval);
}
@ -618,7 +626,7 @@ atomic_cmpset_acq_long(volatile u_long *p, u_long cmpval, u_long newval)
u_long retval;
retval = atomic_cmpset_long(p, cmpval, newval);
rmb();
__ATOMIC_RMB();
return (retval);
}