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qemu/linux-user/mmap.c

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/*
* 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, but addresses are target. */
int target_mprotect(target_ulong start, target_ulong len, int prot)
{
target_ulong 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 & qemu_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);
}
if (host_end == host_start + qemu_host_page_size) {
for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
prot1 |= page_get_flags(addr);
}
end = host_end;
}
ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS);
if (ret != 0)
return ret;
host_start += qemu_host_page_size;
}
if (end < host_end) {
prot1 = prot;
for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
prot1 |= page_get_flags(addr);
}
ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size,
prot1 & PAGE_BITS);
if (ret != 0)
return ret;
host_end -= qemu_host_page_size;
}
/* handle the pages in the middle */
if (host_start < host_end) {
ret = mprotect(g2h(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 */
static int mmap_frag(target_ulong real_start,
target_ulong start, target_ulong end,
int prot, int flags, int fd, target_ulong offset)
{
target_ulong real_end, ret, addr;
void *host_start;
int prot1, prot_new;
real_end = real_start + qemu_host_page_size;
host_start = g2h(real_start);
/* get the protection of the target pages outside the mapping */
prot1 = 0;
for(addr = real_start; addr < real_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(host_start, qemu_host_page_size, prot,
flags | MAP_ANONYMOUS, -1, 0);
if (ret == -1)
return ret;
prot1 = prot;
}
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(host_start, qemu_host_page_size, prot1 | PROT_WRITE);
/* read the corresponding file data */
pread(fd, g2h(start), end - start, offset);
/* put final protection */
if (prot_new != (prot1 | PROT_WRITE))
mprotect(host_start, qemu_host_page_size, prot_new);
} else {
/* just update the protection */
if (prot_new != prot1) {
mprotect(host_start, qemu_host_page_size, prot_new);
}
}
return 0;
}
/* NOTE: all the constants are the HOST ones */
long target_mmap(target_ulong start, target_ulong len, int prot,
int flags, int fd, target_ulong offset)
{
target_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len;
long host_start;
#if defined(__alpha__) || defined(__sparc__) || defined(__x86_64__) || \
defined(__ia64)
static target_ulong last_start = 0x40000000;
#elif defined(__CYGWIN__)
/* Cygwin doesn't have a whole lot of address space. */
static target_ulong last_start = 0x18000000;
#endif
#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) {
errno = EINVAL;
return -1;
}
len = TARGET_PAGE_ALIGN(len);
if (len == 0)
return start;
real_start = start & qemu_host_page_mask;
if (!(flags & MAP_FIXED)) {
#if defined(__alpha__) || defined(__sparc__) || defined(__x86_64__) || \
defined(__ia64) || defined(__CYGWIN__)
/* tell the kenel to search at the same place as i386 */
if (real_start == 0) {
real_start = last_start;
last_start += HOST_PAGE_ALIGN(len);
}
#endif
if (qemu_host_page_size != qemu_real_host_page_size) {
/* NOTE: this code is only for debugging with '-p' option */
/* ??? Can also occur when TARGET_PAGE_SIZE > host page size. */
/* reserve a memory area */
/* ??? This needs fixing for remapping. */
abort();
host_len = HOST_PAGE_ALIGN(len) + qemu_host_page_size - TARGET_PAGE_SIZE;
real_start = (long)mmap(g2h(real_start), host_len, PROT_NONE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (real_start == -1)
return real_start;
real_end = real_start + host_len;
start = HOST_PAGE_ALIGN(real_start);
end = start + HOST_PAGE_ALIGN(len);
if (start > real_start)
munmap((void *)real_start, start - real_start);
if (end < real_end)
munmap((void *)end, real_end - end);
/* use it as a fixed mapping */
flags |= MAP_FIXED;
} else {
/* if not fixed, no need to do anything */
host_offset = offset & qemu_host_page_mask;
host_len = len + offset - host_offset;
host_start = (long)mmap(real_start ? g2h(real_start) : NULL,
host_len, prot, flags, fd, host_offset);
if (host_start == -1)
return host_start;
/* update start so that it points to the file position at 'offset' */
if (!(flags & MAP_ANONYMOUS))
host_start += offset - host_offset;
start = h2g(host_start);
goto the_end1;
}
}
if (start & ~TARGET_PAGE_MASK) {
errno = EINVAL;
return -1;
}
end = start + len;
real_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 & ~qemu_host_page_mask) != (start & ~qemu_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)) {
errno = EINVAL;
return -1;
}
retaddr = target_mmap(start, len, prot | PROT_WRITE,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
-1, 0);
if (retaddr == -1)
return retaddr;
pread(fd, g2h(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 > real_start) {
if (real_end == real_start + qemu_host_page_size) {
/* one single host page */
ret = mmap_frag(real_start, start, end,
prot, flags, fd, offset);
if (ret == -1)
return ret;
goto the_end1;
}
ret = mmap_frag(real_start, start, real_start + qemu_host_page_size,
prot, flags, fd, offset);
if (ret == -1)
return ret;
real_start += qemu_host_page_size;
}
/* handle the end of the mapping */
if (end < real_end) {
ret = mmap_frag(real_end - qemu_host_page_size,
real_end - qemu_host_page_size, real_end,
prot, flags, fd,
offset + real_end - qemu_host_page_size - start);
if (ret == -1)
return ret;
real_end -= qemu_host_page_size;
}
/* map the middle (easier) */
if (real_start < real_end) {
unsigned long offset1;
if (flags & MAP_ANONYMOUS)
offset1 = 0;
else
offset1 = offset + real_start - start;
ret = (long)mmap(g2h(real_start), real_end - real_start,
prot, flags, fd, offset1);
if (ret == -1)
return ret;
}
the_end1:
page_set_flags(start, start + len, prot | PAGE_VALID);
the_end:
#ifdef DEBUG_MMAP
printf("ret=0x%lx\n", (long)start);
page_dump(stdout);
printf("\n");
#endif
return start;
}
int target_munmap(target_ulong start, target_ulong len)
{
target_ulong end, real_start, real_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;
real_start = start & qemu_host_page_mask;
real_end = HOST_PAGE_ALIGN(end);
if (start > real_start) {
/* handle host page containing start */
prot = 0;
for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) {
prot |= page_get_flags(addr);
}
if (real_end == real_start + qemu_host_page_size) {
for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
prot |= page_get_flags(addr);
}
end = real_end;
}
if (prot != 0)
real_start += qemu_host_page_size;
}
if (end < real_end) {
prot = 0;
for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
prot |= page_get_flags(addr);
}
if (prot != 0)
real_end -= qemu_host_page_size;
}
/* unmap what we can */
if (real_start < real_end) {
ret = munmap((void *)real_start, real_end - real_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(target_ulong old_addr, target_ulong old_size,
target_ulong new_size, unsigned long flags,
target_ulong new_addr)
{
int prot;
/* XXX: use 5 args syscall */
new_addr = (long)mremap(g2h(old_addr), old_size, new_size, flags);
if (new_addr == -1)
return new_addr;
new_addr = h2g(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(target_ulong start, target_ulong len, int flags)
{
target_ulong end;
if (start & ~TARGET_PAGE_MASK)
return -EINVAL;
len = TARGET_PAGE_ALIGN(len);
end = start + len;
if (end < start)
return -EINVAL;
if (end == start)
return 0;
start &= qemu_host_page_mask;
return msync(g2h(start), end - start, flags);
}
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