codememory.cpp

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/* src/mm/codememory.c - code memory management

   Copyright (C) 1996-2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/

#include "mm/codememory.hpp"
#include <stdlib.h>                     // for NULL
#include <sys/mman.h>                   // for MAP_PRIVATE, PROT_EXEC, etc
#include "config.h"
#include "mm/memory.hpp"                // for MEMORY_ALIGN, ALIGNSIZE
#include "threads/mutex.hpp"            // for Mutex
#include "vm/options.hpp"
#include "vm/os.hpp"                    // for os
#include "vm/types.hpp"                 // for ptrint
#include "vm/statistics.hpp"

STAT_DECLARE_GROUP(max_mem_stat)
STAT_DECLARE_GROUP(not_freed_mem_stat)
STAT_REGISTER_GROUP_VAR(int,maxcodememusage,0,"maxcodememusage","max. code memory",max_mem_stat)
STAT_REGISTER_GROUP_VAR(int,codememusage,0,"codememusage","max. code memory",not_freed_mem_stat)
/* global code memory variables ***********************************************/

#define DEFAULT_CODE_MEMORY_SIZE    128 * 1024 /* defaulting to 128kB         */

static Mutex  *code_memory_mutex = NULL;
static void   *code_memory       = NULL;
static size_t  code_memory_size  = 0;
static size_t  pagesize          = 0;


/* codememory_init *************************************************************

   Initialize the code memory subsystem.

*******************************************************************************/

void codememory_init(void)
{
    TRACESUBSYSTEMINITIALIZATION("codememory_init");

    /* create mutex for code memory */

    code_memory_mutex = new Mutex();

    /* Get the pagesize of this architecture. */

    pagesize = os::getpagesize();
}


/* codememory_get **************************************************************

   Allocates memory from the heap via mmap and make the memory read-,
   write-, and executeable.

*******************************************************************************/

void *codememory_get(size_t size)
{
    void *p;

    code_memory_mutex->lock();

    size = MEMORY_ALIGN(size, ALIGNSIZE);

    /* check if enough memory is available */

    if (size > code_memory_size) {
        /* set default code size */

        code_memory_size = DEFAULT_CODE_MEMORY_SIZE;

        /* do we need more? */

        if (size > code_memory_size)
            code_memory_size = size;

        /* align the size of the memory to be allocated */

        code_memory_size = MEMORY_ALIGN(code_memory_size, pagesize);

        STATISTICS(codememusage += code_memory_size);
        STATISTICS(maxcodememusage.max(codememusage.get()));

        /* allocate the memory */

        p = os::mmap_anonymous(NULL, code_memory_size,
                               PROT_READ | PROT_WRITE | PROT_EXEC,
                               MAP_PRIVATE);

        /* set global code memory pointer */

        code_memory = p;
    }

    /* get a memory chunk of the allocated memory */

    p = code_memory;

    code_memory       = (void *) ((ptrint) code_memory + size);
    code_memory_size -= size;

    code_memory_mutex->unlock();

    return p;
}


/* codememory_release **********************************************************

   Release the code memory and return it to the code memory
   management.

   IN:
       p ...... pointer to the code memory
       size ... size of the code memory

*******************************************************************************/

void codememory_release(void *p, size_t size)
{
    /* do nothing */
}


/*
 * These are local overrides for various environment variables in Emacs.
 * Please do not remove this and leave it at the end of the file, where
 * Emacs will automagically detect them.
 * ---------------------------------------------------------------------
 * Local variables:
 * mode: c++
 * indent-tabs-mode: t
 * c-basic-offset: 4
 * tab-width: 4
 * End:
 * vim:noexpandtab:sw=4:ts=4:
 */