/* $OpenBSD: mutex.S,v 1.4 2007/05/27 18:34:01 art Exp $ */
/*
* Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "assym.h"
/*
* Yeah, we don't really need to implement mtx_init here, but let's keep
* all the functions in the same place.
*/
ENTRY(mtx_init)
pushl %ebp
movl %esp, %ebp
movl 8(%esp), %eax
movl 12(%esp), %edx
movl %edx, MTX_WANTIPL(%eax)
xorl %edx, %edx
movl %edx, MTX_OLDIPL(%eax)
movl %edx, MTX_LOCK(%eax)
movl %edx, MTX_OWNER(%eax)
leave
ret
#define SOFF 8
ENTRY(mtx_enter)
pushl %ebp
movl %esp, %ebp
1: movl SOFF(%ebp), %ecx
movl MTX_WANTIPL(%ecx), %eax
movl CPL, %edx # oipl = cpl;
cmpl %edx, %eax # if (cpl < mtx->mtx_wantipl)
jle 2f
movl %eax, CPL # cpl = mtx->mtx_wantipl;
2: /*
* %edx now contains the oldipl.
* %ecx contains the mtx.
*/
movl $1, %eax
xchgl %eax, MTX_LOCK(%ecx) # test_and_set(mtx->mtx_lock)
testl %eax, %eax # if (already held)
jnz 3f
movl CPUVAR(SELF), %eax
movl %eax, MTX_OWNER(%ecx)
movl %edx, MTX_OLDIPL(%ecx)
leave
ret
/* We failed to obtain the lock. splx, spin and retry. */
3: pushl %edx
call _C_LABEL(splx)
movl %ebp, %esp
movl SOFF(%ebp), %ecx # %ecx clobbered
4:
#ifdef DIAGNOSTIC
movl CPUVAR(SELF), %edx
cmpl MTX_OWNER(%ecx), %edx
je 5f
#endif
movl MTX_LOCK(%ecx), %eax
testl %eax, %eax
jz 1b
jmp 4b
#ifdef DIAGNOSTIC
5: pushl $6f
call _C_LABEL(panic)
6: .asciz "mtx_enter: locking against myself"
#endif
ENTRY(mtx_leave)
pushl %ebp
movl %esp, %ebp
movl SOFF(%ebp), %ecx
xorl %eax, %eax
movl %eax, MTX_OWNER(%ecx)
pushl MTX_OLDIPL(%ecx)
movl %eax, MTX_OLDIPL(%ecx)
movl %eax, MTX_LOCK(%ecx)
call _C_LABEL(splx)
leave
ret