| /* $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 */ |
| membar #StoreLoad | #LoadLoad |
| lduw [%o0], %g5 |
| sub %g5, 1, %g7 |
| cas [%o0], %g5, %g7 |
| cmp %g5, %g7 |
| be,pt %xcc, 99b |
| nop |
| 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: |
| |
