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Annotation of sys/arch/i386/i386/mutex.S, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: mutex.S,v 1.4 2007/05/27 18:34:01 art Exp $   */
                      2:
                      3: /*
                      4:  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
                      5:  * All rights reserved.
                      6:  *
                      7:  * Redistribution and use in source and binary forms, with or without
                      8:  * modification, are permitted provided that the following conditions
                      9:  * are met:
                     10:  *
                     11:  * 1. Redistributions of source code must retain the above copyright
                     12:  *    notice, this list of conditions and the following disclaimer.
                     13:  * 2. The name of the author may not be used to endorse or promote products
                     14:  *    derived from this software without specific prior written permission.
                     15:  *
                     16:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
                     17:  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
                     18:  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
                     19:  * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
                     20:  * EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLUDING, BUT NOT LIMITED TO,
                     21:  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
                     22:  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
                     23:  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
                     24:  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
                     25:  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
                     26:  */
                     27:
                     28: #include "assym.h"
                     29: /*
                     30:  * Yeah, we don't really need to implement mtx_init here, but let's keep
                     31:  * all the functions in the same place.
                     32:  */
                     33: ENTRY(mtx_init)
                     34:        pushl   %ebp
                     35:        movl    %esp, %ebp
                     36:        movl    8(%esp), %eax
                     37:        movl    12(%esp), %edx
                     38:        movl    %edx, MTX_WANTIPL(%eax)
                     39:        xorl    %edx, %edx
                     40:        movl    %edx, MTX_OLDIPL(%eax)
                     41:        movl    %edx, MTX_LOCK(%eax)
                     42:        movl    %edx, MTX_OWNER(%eax)
                     43:        leave
                     44:        ret
                     45:
                     46: #define SOFF   8
                     47:
                     48: ENTRY(mtx_enter)
                     49:        pushl   %ebp
                     50:        movl    %esp, %ebp
                     51: 1:     movl    SOFF(%ebp), %ecx
                     52:        movl    MTX_WANTIPL(%ecx), %eax
                     53:        movl    CPL, %edx               # oipl = cpl;
                     54:        cmpl    %edx, %eax              # if (cpl < mtx->mtx_wantipl)
                     55:        jle     2f
                     56:        movl    %eax, CPL               #       cpl = mtx->mtx_wantipl;
                     57: 2:     /*
                     58:         * %edx now contains the oldipl.
                     59:         * %ecx contains the mtx.
                     60:         */
                     61:        movl    $1, %eax
                     62:        xchgl   %eax, MTX_LOCK(%ecx)    # test_and_set(mtx->mtx_lock)
                     63:        testl   %eax, %eax              # if (already held)
                     64:        jnz     3f
                     65:        movl    CPUVAR(SELF), %eax
                     66:        movl    %eax, MTX_OWNER(%ecx)
                     67:        movl    %edx, MTX_OLDIPL(%ecx)
                     68:        leave
                     69:        ret
                     70:
                     71:        /* We failed to obtain the lock. splx, spin and retry. */
                     72: 3:     pushl   %edx
                     73:        call    _C_LABEL(splx)
                     74:        movl    %ebp, %esp
                     75:        movl    SOFF(%ebp), %ecx                # %ecx clobbered
                     76: 4:
                     77: #ifdef DIAGNOSTIC
                     78:        movl    CPUVAR(SELF), %edx
                     79:        cmpl    MTX_OWNER(%ecx), %edx
                     80:        je      5f
                     81: #endif
                     82:        movl    MTX_LOCK(%ecx), %eax
                     83:        testl   %eax, %eax
                     84:        jz      1b
                     85:        jmp     4b
                     86: #ifdef DIAGNOSTIC
                     87: 5:     pushl   $6f
                     88:        call    _C_LABEL(panic)
                     89: 6:     .asciz  "mtx_enter: locking against myself"
                     90: #endif
                     91:
                     92: ENTRY(mtx_leave)
                     93:        pushl   %ebp
                     94:        movl    %esp, %ebp
                     95:        movl    SOFF(%ebp), %ecx
                     96:        xorl    %eax, %eax
                     97:        movl    %eax, MTX_OWNER(%ecx)
                     98:        pushl   MTX_OLDIPL(%ecx)
                     99:        movl    %eax, MTX_OLDIPL(%ecx)
                    100:        movl    %eax, MTX_LOCK(%ecx)
                    101:        call    _C_LABEL(splx)
                    102:        leave
                    103:        ret