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/* $Id: rwlock.S,v 1.4 2000/09/09 00:00:34 davem Exp $
* rwlocks.S: These things are too big to do inline.
*
* Copyright (C) 1999 David S. Miller (davem@redhat.com)
*/
.text
.align 64
.globl rwlock_impl_begin, rwlock_impl_end
/* The non-contention read lock usage is 2 cache lines. */
.globl __read_lock, __read_unlock
rwlock_impl_begin:
__read_lock: /* %o0 = lock_ptr */
ldsw [%o0], %g5
brlz,pn %g5, __read_wait_for_writer
4: add %g5, 1, %g7
cas [%o0], %g5, %g7
cmp %g5, %g7
bne,pn %icc, __read_lock
membar #StoreLoad | #StoreStore
99: retl
nop
__read_unlock: /* %o0 = lock_ptr */
lduw [%o0], %g5
sub %g5, 1, %g7
cas [%o0], %g5, %g7
cmp %g5, %g7
be,pt %xcc, 99b
membar #StoreLoad | #StoreStore
ba,a,pt %xcc, __read_unlock
__read_wait_for_writer:
ldsw [%o0], %g5
brlz,pt %g5, __read_wait_for_writer
membar #LoadLoad
ba,a,pt %xcc, 4b
__write_wait_for_any:
lduw [%o0], %g5
brnz,pt %g5, __write_wait_for_any
membar #LoadLoad
ba,a,pt %xcc, 4f
.align 64
.globl __write_unlock
__write_unlock: /* %o0 = lock_ptr */
membar #LoadStore | #StoreStore
retl
stw %g0, [%o0]
.globl __write_lock
__write_lock: /* %o0 = lock_ptr */
sethi %hi(0x80000000), %g2
1: lduw [%o0], %g5
brnz,pn %g5, __write_wait_for_any
4: or %g5, %g2, %g7
cas [%o0], %g5, %g7
cmp %g5, %g7
be,pt %icc, 99b
membar #StoreLoad | #StoreStore
ba,a,pt %xcc, 1b
rwlock_impl_end:
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