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