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atomic: Add atomic_cmpset_masked to powerpc and use it

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Summary:
This is a more optimal way of doing atomic_compset_masked() than the
fallback in sys/_atomic_subword.h.  There's also an override for
_atomic_fcmpset_masked_word(), which may or may not be necessary, and is
unused for powerpc.

Reviewed by:	kevans, kib
Differential Revision:	https://reviews.freebsd.org/D22359
This commit is contained in:
Justin Hibbits 2019-11-15 04:33:07 +00:00
parent a109294221
commit d0bdb11139
2 changed files with 36 additions and 0 deletions
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32
sys/powerpc/include/atomic.h
View File

@ -608,6 +608,38 @@ atomic_cmpset_short(volatile u_short *p, u_short cmpval, u_short newval)
return (ret);
}
#else
static __inline int
atomic_cmpset_masked(uint32_t *p, uint32_t cmpval, uint32_t newval,
uint32_t mask)
{
int ret;
uint32_t tmp;
__asm __volatile (
"1:\tlwarx %2, 0, %2\n\t" /* load old value */
"and %0, %2, %7\n\t"
"cmplw %4, %0\n\t" /* compare */
"bne- 2f\n\t" /* exit if not equal */
"andc %2, %2, %7\n\t"
"or %2, %2, %5\n\t"
"stwcx. %2, 0, %3\n\t" /* attempt to store */
"bne- 1b\n\t" /* spin if failed */
"li %0, 1\n\t" /* success - retval = 1 */
"b 3f\n\t" /* we've succeeded */
"2:\n\t"
"stwcx. %2, 0, %3\n\t" /* clear reservation (74xx) */
"li %0, 0\n\t" /* failure - retval = 0 */
"3:\n\t"
: "=&r" (ret), "=m" (*p), "+&r" (tmp)
: "r" (p), "r" (cmpval), "r" (newval), "m" (*p),
"r" (mask)
: "cr0", "memory");
return (ret);
}
#define _atomic_cmpset_masked_word(a,o,v,m) atomic_cmpset_masked(a, o, v, m)
#endif
static __inline int

4
sys/sys/_atomic_subword.h
View File

@ -63,6 +63,7 @@
((((__uintptr_t)(p) % 4)) * NBBY)
#endif
#ifndef _atomic_cmpset_masked_word
/*
* Pass these bad boys a couple words and a mask of the bits you care about,
* they'll loop until we either succeed or fail because of those bits rather
@ -92,7 +93,9 @@ _atomic_cmpset_masked_word(uint32_t *addr, uint32_t old, uint32_t val,
return (ret);
}
#endif
#ifndef _atomic_fcmpset_masked_word
static __inline int
_atomic_fcmpset_masked_word(uint32_t *addr, uint32_t *old, uint32_t val,
uint32_t mask)
@ -108,6 +111,7 @@ _atomic_fcmpset_masked_word(uint32_t *addr, uint32_t *old, uint32_t val,
*old = (*addr & ~mask) | *old;
return (atomic_fcmpset_32(addr, old, (*old & ~mask) | val));
}
#endif
static __inline int
atomic_cmpset_8(__volatile uint8_t *addr, uint8_t old, uint8_t val)