Archipelago » qemu

/*

 *  mmap support for qemu

 * 

 *  Copyright (c) 2003 Fabrice Bellard

 *

 *  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 of the License, 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., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

#include <stdlib.h>

#include <stdio.h>

#include <stdarg.h>

#include <string.h>

#include <unistd.h>

#include <errno.h>

#include <sys/mman.h>

#include "qemu.h"

//#define DEBUG_MMAP

/* NOTE: all the constants are the HOST ones */

int target_mprotect(unsigned long start, unsigned long len, int prot)

{

    unsigned long end, host_start, host_end, addr;

    int prot1, ret;

#ifdef DEBUG_MMAP

    printf("mprotect: start=0x%lx len=0x%lx prot=%c%c%c\n", start, len,

           prot & PROT_READ ? 'r' : '-',

           prot & PROT_WRITE ? 'w' : '-',

           prot & PROT_EXEC ? 'x' : '-');

#endif

    if ((start & ~TARGET_PAGE_MASK) != 0)

        return -EINVAL;

    len = TARGET_PAGE_ALIGN(len);

    end = start + len;

    if (end < start)

        return -EINVAL;

    if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC))

        return -EINVAL;

    if (len == 0)

        return 0;

    host_start = start & host_page_mask;

    host_end = HOST_PAGE_ALIGN(end);

    if (start > host_start) {

        /* handle host page containing start */

        prot1 = prot;

        for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {

            prot1 |= page_get_flags(addr);

        }

        ret = mprotect((void *)host_start, host_page_size, prot1 & PAGE_BITS);

        if (ret != 0)

            return ret;

        host_start += host_page_size;

    }

    if (end < host_end) {

        /* handle host page containing end (can be the same as first page) */

        prot1 = prot;

        for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {

            prot1 |= page_get_flags(addr);

        }

        ret = mprotect((void *)(host_end - host_page_size), host_page_size, 

                       prot1 & PAGE_BITS);

        if (ret != 0)

            return ret;

        host_end -= host_page_size;

    }

    /* handle the pages in the middle */

    if (host_start < host_end) {

        ret = mprotect((void *)host_start, host_end - host_start, prot);

        if (ret != 0)

            return ret;

    }

    page_set_flags(start, start + len, prot | PAGE_VALID);

    return 0;

}

/* map an incomplete host page */

int mmap_frag(unsigned long host_start, 

               unsigned long start, unsigned long end, 

               int prot, int flags, int fd, unsigned long offset)

{

    unsigned long host_end, ret, addr;

    int prot1, prot_new;

    host_end = host_start + host_page_size;

    /* get the protection of the target pages outside the mapping */

    prot1 = 0;

    for(addr = host_start; addr < host_end; addr++) {

        if (addr < start || addr >= end)

            prot1 |= page_get_flags(addr);

    }

    if (prot1 == 0) {

        /* no page was there, so we allocate one */

        ret = (long)mmap((void *)host_start, host_page_size, prot, 

                         flags | MAP_ANONYMOUS, -1, 0);

        if (ret == -1)

            return ret;

    }

    prot1 &= PAGE_BITS;

    prot_new = prot | prot1;

    if (!(flags & MAP_ANONYMOUS)) {

        /* msync() won't work here, so we return an error if write is

           possible while it is a shared mapping */

        if ((flags & MAP_TYPE) == MAP_SHARED &&

            (prot & PROT_WRITE))

            return -EINVAL;

        /* adjust protection to be able to read */

        if (!(prot1 & PROT_WRITE))

            mprotect((void *)host_start, host_page_size, prot1 | PROT_WRITE);

        /* read the corresponding file data */

        pread(fd, (void *)start, end - start, offset);

        /* put final protection */

        if (prot_new != (prot1 | PROT_WRITE))

            mprotect((void *)host_start, host_page_size, prot_new);

    } else {

        /* just update the protection */

        if (prot_new != prot1) {

            mprotect((void *)host_start, host_page_size, prot_new);

        }

    }

    return 0;

}

/* NOTE: all the constants are the HOST ones */

long target_mmap(unsigned long start, unsigned long len, int prot, 

                 int flags, int fd, unsigned long offset)

{

    unsigned long ret, end, host_start, host_end, retaddr, host_offset, host_len;

#ifdef DEBUG_MMAP

    {

        printf("mmap: start=0x%lx len=0x%lx prot=%c%c%c flags=",

               start, len, 

               prot & PROT_READ ? 'r' : '-',

               prot & PROT_WRITE ? 'w' : '-',

               prot & PROT_EXEC ? 'x' : '-');

        if (flags & MAP_FIXED)

            printf("MAP_FIXED ");

        if (flags & MAP_ANONYMOUS)

            printf("MAP_ANON ");

        switch(flags & MAP_TYPE) {

        case MAP_PRIVATE:

            printf("MAP_PRIVATE ");

            break;

        case MAP_SHARED:

            printf("MAP_SHARED ");

            break;

        default:

            printf("[MAP_TYPE=0x%x] ", flags & MAP_TYPE);

            break;

        }

        printf("fd=%d offset=%lx\n", fd, offset);

    }

#endif

    if (offset & ~TARGET_PAGE_MASK)

        return -EINVAL;

    len = TARGET_PAGE_ALIGN(len);

    if (len == 0)

        return start;

    host_start = start & host_page_mask;

    if (!(flags & MAP_FIXED)) {

        if (host_page_size != real_host_page_size) {

            /* NOTE: this code is only for debugging with '-p' option */

            /* reserve a memory area */

            host_len = HOST_PAGE_ALIGN(len) + host_page_size - TARGET_PAGE_SIZE;

            host_start = (long)mmap((void *)host_start, host_len, PROT_NONE, 

                                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

            if (host_start == -1)

                return host_start;

            host_end = host_start + host_len;

            start = HOST_PAGE_ALIGN(host_start);

            end = start + HOST_PAGE_ALIGN(len);

            if (start > host_start)

                munmap((void *)host_start, start - host_start);

            if (end < host_end)

                munmap((void *)end, host_end - end);

            /* use it as a fixed mapping */

            flags |= MAP_FIXED;

        } else {

            /* if not fixed, no need to do anything */

            host_offset = offset & host_page_mask;

            host_len = len + offset - host_offset;

            start = (long)mmap((void *)host_start, host_len, 

                               prot, flags, fd, host_offset);

            if (start == -1)

                return start;

            /* update start so that it points to the file position at 'offset' */

            if (!(flags & MAP_ANONYMOUS)) 

                start += offset - host_offset;

            goto the_end1;

        }

    }

    if (start & ~TARGET_PAGE_MASK)

        return -EINVAL;

    end = start + len;

    host_end = HOST_PAGE_ALIGN(end);

    /* worst case: we cannot map the file because the offset is not

       aligned, so we read it */

    if (!(flags & MAP_ANONYMOUS) &&

        (offset & ~host_page_mask) != (start & ~host_page_mask)) {

        /* msync() won't work here, so we return an error if write is

           possible while it is a shared mapping */

        if ((flags & MAP_TYPE) == MAP_SHARED &&

            (prot & PROT_WRITE))

            return -EINVAL;

        retaddr = target_mmap(start, len, prot | PROT_WRITE, 

                              MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, 

                              -1, 0);

        if (retaddr == -1)

            return retaddr;

        pread(fd, (void *)start, len, offset);

        if (!(prot & PROT_WRITE)) {

            ret = target_mprotect(start, len, prot);

            if (ret != 0)

                return ret;

        }

        goto the_end;

    }

    /* handle the start of the mapping */

    if (start > host_start) {

        if (host_end == host_start + host_page_size) {

            /* one single host page */

            ret = mmap_frag(host_start, start, end,

                            prot, flags, fd, offset);

            if (ret == -1)

                return ret;

            goto the_end1;

        }

        ret = mmap_frag(host_start, start, host_start + host_page_size,

                        prot, flags, fd, offset);

        if (ret == -1)

            return ret;

        host_start += host_page_size;

    }

    /* handle the end of the mapping */

    if (end < host_end) {

        ret = mmap_frag(host_end - host_page_size, 

                        host_end - host_page_size, host_end,

                        prot, flags, fd, 

                        offset + host_end - host_page_size - start);

        if (ret == -1)

            return ret;

        host_end -= host_page_size;

    }

    /* map the middle (easier) */

    if (host_start < host_end) {

        ret = (long)mmap((void *)host_start, host_end - host_start, 

                         prot, flags, fd, offset + host_start - start);

        if (ret == -1)

            return ret;

    }

 the_end1:

    page_set_flags(start, start + len, prot | PAGE_VALID);

 the_end:

#ifdef DEBUG_MMAP

    page_dump(stdout);

    printf("\n");

#endif

    return start;

}

int target_munmap(unsigned long start, unsigned long len)

{

    unsigned long end, host_start, host_end, addr;

    int prot, ret;

#ifdef DEBUG_MMAP

    printf("munmap: start=0x%lx len=0x%lx\n", start, len);

#endif

    if (start & ~TARGET_PAGE_MASK)

        return -EINVAL;

    len = TARGET_PAGE_ALIGN(len);

    if (len == 0)

        return -EINVAL;

    end = start + len;

    host_start = start & host_page_mask;

    host_end = HOST_PAGE_ALIGN(end);

    if (start > host_start) {

        /* handle host page containing start */

        prot = 0;

        for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {

            prot |= page_get_flags(addr);

        }

        if (prot != 0)

            host_start += host_page_size;

    }

    if (end < host_end) {

        /* handle host page containing end (can be the same as first page) */

        prot = 0;

        for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {

            prot |= page_get_flags(addr);

        }

        if (prot != 0)

            host_end -= host_page_size;

    }

    /* unmap what we can */

    if (host_start < host_end) {

        ret = munmap((void *)host_start, host_end - host_start);

        if (ret != 0)

            return ret;

    }

    page_set_flags(start, start + len, 0);

    return 0;

}

/* XXX: currently, we only handle MAP_ANONYMOUS and not MAP_FIXED

   blocks which have been allocated starting on a host page */

long target_mremap(unsigned long old_addr, unsigned long old_size, 

                   unsigned long new_size, unsigned long flags,

                   unsigned long new_addr)

{

    int prot;

    /* XXX: use 5 args syscall */

    new_addr = (long)mremap((void *)old_addr, old_size, new_size, flags);

    if (new_addr == -1)

        return new_addr;

    prot = page_get_flags(old_addr);

    page_set_flags(old_addr, old_addr + old_size, 0);

    page_set_flags(new_addr, new_addr + new_size, prot | PAGE_VALID);

    return new_addr;

}

int target_msync(unsigned long start, unsigned long len, int flags)

{

    unsigned long end;

    if (start & ~TARGET_PAGE_MASK)

        return -EINVAL;

    len = TARGET_PAGE_ALIGN(len);

    if (len == 0)

        return 0;

    end = start + len;

    start &= host_page_mask;

    return msync((void *)start, len, flags);

}