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Annotation of objc/objc-moninit-i386.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.0 (the 'License').  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License."
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: #ifdef SHLIB
        !            25: #import "shlib.h"
        !            26: #undef moninitobjc
        !            27: #endif
        !            28: 
        !            29: #ifndef __i386__
        !            30: #error "this is i386 machine dependent"
        !            31: #endif
        !            32: 
        !            33: #include <mach/mach.h>
        !            34: 
        !            35: /*
        !            36:  * objc_exitPoints is a private_extern defined in the objective-C messager
        !            37:  * which is a zero terminated table of a list of text lables to write
        !            38:  * instructions which will cause the objective-C messager to then call
        !            39:  * moncount for each message it dispatches.  The instruction at each of these
        !            40:  * text lables is a "jmp *%eax@" instruction.  The objective-C messager has
        !            41:  * allocated space after each of these instructions for moninitobjc to write
        !            42:  * the instructions to call moncount for each message it dispatches.
        !            43:  * 
        !            44:  * The instructions written over the "jmp *%eax@" and the allocated space after
        !            45:  * it are:
        !            46:  * exitPoint1: jmp     *%eax@
        !            47:  *             | replace with the following instructions
        !            48:  *             pushl   %eax
        !            49:  *             pushl   %eax
        !            50:  *             pushl   8(%esp)
        !            51:  *             call    _moncount
        !            52:  *             addl    $8,%esp
        !            53:  *             popl    %eax
        !            54:  *             jmp     *%eax@
        !            55:  */
        !            56: extern unsigned long objc_exitPoints[];
        !            57: 
        !            58: /*
        !            59:  * objc_entryPoints is a private_extern defined in the objective-C messager
        !            60:  * which is a zero terminated table of a list of text lables that should not
        !            61:  * have a call inserted to moncount in their shared library branch table slot.
        !            62:  */
        !            63: extern unsigned long objc_entryPoints[];
        !            64: 
        !            65: /*
        !            66:  * moninitobjc() is a machine dependent routine that causes objective-C
        !            67:  * messager to call moncount() for each message it sends.
        !            68:  */
        !            69: unsigned long *
        !            70: moninitobjc(
        !            71: unsigned long moncount_addr)
        !            72: {
        !            73:     unsigned long i, min, max, addr;
        !            74:     char *p;
        !            75:     kern_return_t r;
        !            76: 
        !            77:        if(objc_exitPoints[0] == 0)
        !            78:            return(objc_entryPoints);
        !            79: 
        !            80:        /*
        !            81:         * Determine the area to vm_protect() for writing the code.
        !            82:         */
        !            83:        min = 0xffffffff;
        !            84:        max = 0;
        !            85:        for(i = 0; objc_exitPoints[i] != 0; i++){
        !            86:            if(objc_exitPoints[i] < min)
        !            87:                min = objc_exitPoints[i];
        !            88:            if(objc_exitPoints[i] > max)
        !            89:                max = objc_exitPoints[i];
        !            90:        }
        !            91:        max += 24;
        !            92: 
        !            93:        if((r = vm_protect(task_self(), (vm_address_t)min, (vm_size_t)(max-min),
        !            94:                           FALSE, VM_PROT_READ | VM_PROT_WRITE |
        !            95:                           VM_PROT_EXECUTE)) != KERN_SUCCESS)
        !            96:            return(objc_entryPoints);
        !            97: 
        !            98:        /*
        !            99:         * Write in the code to call moncount.
        !           100:         */
        !           101:        for(i = 0; objc_exitPoints[i] != 0; i++){
        !           102:            p = (char *)(objc_exitPoints[i]);
        !           103:            /* pushl %eax */
        !           104:            *p++ = 0x50;
        !           105:            /* pushl %eax */
        !           106:            *p++ = 0x50;
        !           107:            /* pushl 8(%esp) */
        !           108:            *p++ = 0xff;
        !           109:            *p++ = 0x74;
        !           110:            *p++ = 0x24;
        !           111:            *p++ = 0x08;
        !           112:            /* call moncount */
        !           113:            addr = moncount_addr - ((unsigned long)p + 5);
        !           114:            *p++ = 0xe8;
        !           115:            *p++ = (addr) & 0xff;
        !           116:            *p++ = (addr >>  8) & 0xff;
        !           117:            *p++ = (addr >> 16) & 0xff;
        !           118:            *p++ = (addr >> 24) & 0xff;
        !           119:            /* addl $0x08,%esp */
        !           120:            *p++ = 0x83;
        !           121:            *p++ = 0xc4;
        !           122:            *p++ = 0x08;
        !           123:            /* popl %eax */
        !           124:            *p++ = 0x58;
        !           125:            /* jmp *%eax@ */
        !           126:            *p++ = 0xff;
        !           127:            *p++ = 0xe0;
        !           128:        }
        !           129:        /*
        !           130:         * The text cache for the this code now needs to be flushed since
        !           131:         * it was just written on so that future calls will get the new
        !           132:         * instructions.
        !           133:        cache_flush(min, max-min);
        !           134:         */
        !           135:        asm("jmp 1f");
        !           136:        asm("1: nop");
        !           137: 
        !           138:        return(objc_entryPoints);
        !           139: }

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