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/* $Id: locks.S,v 1.15 1998/10/14 09:18:55 jj Exp $
* locks.S: SMP low-level lock primitives on Sparc.
*
* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1998 Anton Blanchard (anton@progsoc.uts.edu.au)
* Copyright (C) 1998 Jakub Jelinek (jj@ultra.linux.cz)
*/
#include <asm/cprefix.h>
#include <asm/ptrace.h>
#include <asm/psr.h>
#include <asm/smp.h>
#include <asm/spinlock.h>
.text
.align 4
/* This is called when the initial acquisition attempt of a spin
* lock fails. The calling convention is weird, return address
* is in %o7 as usual but we agree with the caller to only touch
* and use %g2 as a temporary. We are passed a ptr to the lock
* itself in %g1, %g4 must be restored into %o7 when we return,
* and the caller wants us to return to him at three instructions
* previous to the call instruction which got us here. See how
* this is used in asm/spinlock.h if what I just said confuses
* you to no end.
*/
.globl ___spinlock_waitfor
___spinlock_waitfor:
1: orcc %g2, 0x0, %g0
bne,a 1b
ldub [%g1], %g2
ldstub [%g1], %g2
jmpl %o7 - 12, %g0
mov %g4, %o7
/* Read/writer locks, as usual this is overly clever to make it
* as fast as possible.
*/
/* caches... */
___rw_read_enter_spin_on_wlock:
orcc %g2, 0x0, %g0
be,a ___rw_read_enter
ldstub [%g1 + 3], %g2
b ___rw_read_enter_spin_on_wlock
ldub [%g1 + 3], %g2
___rw_read_exit_spin_on_wlock:
orcc %g2, 0x0, %g0
be,a ___rw_read_exit
ldstub [%g1 + 3], %g2
b ___rw_read_exit_spin_on_wlock
ldub [%g1 + 3], %g2
___rw_write_enter_spin_on_wlock:
orcc %g2, 0x0, %g0
be,a ___rw_write_enter
ldstub [%g1 + 3], %g2
b ___rw_write_enter_spin_on_wlock
ld [%g1], %g2
.globl ___rw_read_enter
___rw_read_enter:
orcc %g2, 0x0, %g0
bne,a ___rw_read_enter_spin_on_wlock
ldub [%g1 + 3], %g2
ld [%g1], %g2
add %g2, 1, %g2
st %g2, [%g1]
retl
mov %g4, %o7
.globl ___rw_read_exit
___rw_read_exit:
orcc %g2, 0x0, %g0
bne,a ___rw_read_exit_spin_on_wlock
ldub [%g1 + 3], %g2
ld [%g1], %g2
sub %g2, 0x1ff, %g2
st %g2, [%g1]
retl
mov %g4, %o7
.globl ___rw_write_enter
___rw_write_enter:
orcc %g2, 0x0, %g0
bne ___rw_write_enter_spin_on_wlock
ld [%g1], %g2
andncc %g2, 0xff, %g0
bne,a ___rw_write_enter_spin_on_wlock
stb %g0, [%g1 + 3]
retl
mov %g4, %o7
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