mmap emulation

[thirdparty/qemu.git] / exec.c

/*
 *  virtual page mapping
 * 
 *  Copyright (c) 2003 Fabrice Bellard
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <inttypes.h>

#include "cpu-i386.h"

/* XXX: pack the flags in the low bits of the pointer ? */
typedef struct PageDesc {
    struct TranslationBlock *first_tb;
    unsigned long flags;
} PageDesc;

#define L2_BITS 10
#define L1_BITS (32 - L2_BITS - TARGET_PAGE_BITS)

#define L1_SIZE (1 << L1_BITS)
#define L2_SIZE (1 << L2_BITS)

unsigned long real_host_page_size;
unsigned long host_page_bits;
unsigned long host_page_size;
unsigned long host_page_mask;

static PageDesc *l1_map[L1_SIZE];

void page_init(void)
{
    /* NOTE: we can always suppose that host_page_size >=
       TARGET_PAGE_SIZE */
    real_host_page_size = getpagesize();
    if (host_page_size == 0)
        host_page_size = real_host_page_size;
    if (host_page_size < TARGET_PAGE_SIZE)
        host_page_size = TARGET_PAGE_SIZE;
    host_page_bits = 0;
    while ((1 << host_page_bits) < host_page_size)
        host_page_bits++;
    host_page_mask = ~(host_page_size - 1);
}

/* dump memory mappings */
void page_dump(FILE *f)
{
    unsigned long start, end;
    int i, j, prot, prot1;
    PageDesc *p;

    fprintf(f, "%-8s %-8s %-8s %s\n",
            "start", "end", "size", "prot");
    start = -1;
    end = -1;
    prot = 0;
    for(i = 0; i <= L1_SIZE; i++) {
        if (i < L1_SIZE)
            p = l1_map[i];
        else
            p = NULL;
        for(j = 0;j < L2_SIZE; j++) {
            if (!p)
                prot1 = 0;
            else
                prot1 = p[j].flags;
            if (prot1 != prot) {
                end = (i << (32 - L1_BITS)) | (j << TARGET_PAGE_BITS);
                if (start != -1) {
                    fprintf(f, "%08lx-%08lx %08lx %c%c%c\n",
                            start, end, end - start, 
                            prot & PAGE_READ ? 'r' : '-',
                            prot & PAGE_WRITE ? 'w' : '-',
                            prot & PAGE_EXEC ? 'x' : '-');
                }
                if (prot1 != 0)
                    start = end;
                else
                    start = -1;
                prot = prot1;
            }
            if (!p)
                break;
        }
    }
}


static inline PageDesc *page_find_alloc(unsigned long address)
{
    unsigned int index;
    PageDesc **lp, *p;

    index = address >> TARGET_PAGE_BITS;
    lp = &l1_map[index >> L2_BITS];
    p = *lp;
    if (!p) {
        /* allocate if not found */
        p = malloc(sizeof(PageDesc) * L2_SIZE);
        memset(p, 0, sizeof(sizeof(PageDesc) * L2_SIZE));
        *lp = p;
    }
    return p + (index & (L2_SIZE - 1));
}

int page_get_flags(unsigned long address)
{
    unsigned int index;
    PageDesc *p;

    index = address >> TARGET_PAGE_BITS;
    p = l1_map[index >> L2_BITS];
    if (!p)
        return 0;
    return p[index & (L2_SIZE - 1)].flags;
}

void page_set_flags(unsigned long start, unsigned long end, int flags)
{
    PageDesc *p;
    unsigned long addr;

    start = start & TARGET_PAGE_MASK;
    end = TARGET_PAGE_ALIGN(end);
    for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {
        p = page_find_alloc(addr);
        p->flags = flags;
    }
}