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unixgc.c
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00001 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
00002 /* ***** BEGIN LICENSE BLOCK *****
00003  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
00004  *
00005  * The contents of this file are subject to the Mozilla Public License Version
00006  * 1.1 (the "License"); you may not use this file except in compliance with
00007  * the License. You may obtain a copy of the License at
00008  * http://www.mozilla.org/MPL/
00009  *
00010  * Software distributed under the License is distributed on an "AS IS" basis,
00011  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
00012  * for the specific language governing rights and limitations under the
00013  * License.
00014  *
00015  * The Original Code is the Netscape Portable Runtime (NSPR).
00016  *
00017  * The Initial Developer of the Original Code is
00018  * Netscape Communications Corporation.
00019  * Portions created by the Initial Developer are Copyright (C) 1998-2000
00020  * the Initial Developer. All Rights Reserved.
00021  *
00022  * Contributor(s):
00023  *
00024  * Alternatively, the contents of this file may be used under the terms of
00025  * either the GNU General Public License Version 2 or later (the "GPL"), or
00026  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
00027  * in which case the provisions of the GPL or the LGPL are applicable instead
00028  * of those above. If you wish to allow use of your version of this file only
00029  * under the terms of either the GPL or the LGPL, and not to allow others to
00030  * use your version of this file under the terms of the MPL, indicate your
00031  * decision by deleting the provisions above and replace them with the notice
00032  * and other provisions required by the GPL or the LGPL. If you do not delete
00033  * the provisions above, a recipient may use your version of this file under
00034  * the terms of any one of the MPL, the GPL or the LGPL.
00035  *
00036  * ***** END LICENSE BLOCK ***** */
00037 
00038 #include "prlock.h"
00039 #include "prlog.h"
00040 #include "prmem.h"
00041 #include "gcint.h"
00042 
00043 #include <stdio.h>
00044 #include <sys/types.h>
00045 #include <sys/stat.h>
00046 #include <fcntl.h>
00047 #include <sys/mman.h>
00048 
00049 #define _PR_GC_VMBASE 0x40000000
00050 
00051 #if defined(SOLARIS)
00052 #define _MD_MMAP_FLAGS MAP_SHARED
00053 #elif defined(RELIANTUNIX)
00054 #define _MD_MMAP_FLAGS MAP_PRIVATE|MAP_FIXED
00055 #else
00056 #define _MD_MMAP_FLAGS MAP_PRIVATE
00057 #endif
00058 
00059 static PRInt32 zero_fd = -1;
00060 static PRLock *zero_fd_lock = NULL;
00061 
00062 void _MD_InitGC(void)
00063 {
00064 #ifdef DEBUG
00065     /*
00066      * Disable using mmap(2) if NSPR_NO_MMAP is set
00067      */
00068     if (getenv("NSPR_NO_MMAP")) {
00069         zero_fd = -2;
00070         return;
00071     }
00072 #endif
00073     zero_fd = open("/dev/zero",O_RDWR , 0);
00074     zero_fd_lock = PR_NewLock();
00075 }
00076 
00077 /* This static variable is used by _MD_GrowGCHeap and _MD_ExtendGCHeap */
00078 static void *lastaddr = (void*) _PR_GC_VMBASE;
00079 
00080 void *_MD_GrowGCHeap(PRUint32 *sizep)
00081 {
00082        void *addr;
00083        PRUint32 size;
00084 
00085        size = *sizep;
00086 
00087        PR_Lock(zero_fd_lock);
00088        if (zero_fd < 0) {
00089               goto mmap_loses;
00090        }
00091 
00092        /* Extend the mapping */
00093        addr = mmap(lastaddr, size, PROT_READ|PROT_WRITE|PROT_EXEC,
00094            _MD_MMAP_FLAGS,
00095            zero_fd, 0);
00096        if (addr == (void*)-1) {
00097               zero_fd = -1;
00098               goto mmap_loses;
00099        }
00100        lastaddr = ((char*)addr + size);
00101 #ifdef DEBUG
00102        PR_LOG(_pr_msgc_lm, PR_LOG_WARNING,
00103            ("GC: heap extends from %08x to %08x\n",
00104            _PR_GC_VMBASE,
00105            _PR_GC_VMBASE + (char*)lastaddr - (char*)_PR_GC_VMBASE));
00106 #endif
00107        PR_Unlock(zero_fd_lock);
00108        return addr;
00109 
00110 mmap_loses:
00111        PR_Unlock(zero_fd_lock);
00112        return PR_MALLOC(size);
00113 }
00114 
00115 /* XXX - This is disabled.  MAP_FIXED just does not work. */
00116 #if 0
00117 PRBool _MD_ExtendGCHeap(char *base, PRInt32 oldSize, PRInt32 newSize) {
00118        PRBool rv = PR_FALSE;
00119        void* addr;
00120        PRInt32 allocSize = newSize - oldSize;
00121 
00122        PR_Lock(zero_fd_lock);
00123        addr = mmap(base + oldSize, allocSize, PROT_READ|PROT_WRITE|PROT_EXEC,
00124            _MD_MMAP_FLAGS | MAP_FIXED, zero_fd, 0);
00125        if (addr == (void*)-1) {
00126               goto loser;
00127        }
00128        if (addr != (void*) (base + oldSize)) {
00129               munmap(base + oldSize, allocSize);
00130               goto loser;
00131        }
00132        lastaddr = ((char*)base + newSize);
00133        PR_LOG(_pr_msgc_lm, PR_LOG_ALWAYS,
00134            ("GC: heap now extends from %p to %p",
00135            base, base + newSize));
00136        rv = PR_TRUE;
00137 
00138 loser:
00139        PR_Unlock(zero_fd_lock);
00140        return rv;
00141 }
00142 #else
00143 PRBool _MD_ExtendGCHeap(char *base, PRInt32 oldSize, PRInt32 newSize) {
00144        return PR_FALSE;
00145 }
00146 #endif
00147 
00148 void _MD_FreeGCSegment(void *base, PRInt32 len)
00149 {
00150        if (zero_fd < 0) {
00151               PR_DELETE(base);
00152        } else {
00153               (void) munmap(base, len);
00154        }
00155 }