/*
* mmap support for qemu
*
* Copyright (c) 2003 - 2008 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, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu.h"
#include "qemu-common.h"
#include "bsd-mman.h"
#include "exec/exec-all.h"
//#define DEBUG_MMAP
static pthread_mutex_t mmap_mutex = PTHREAD_MUTEX_INITIALIZER;
static __thread int mmap_lock_count;
void mmap_lock(void)
{
if (mmap_lock_count++ == 0) {
pthread_mutex_lock(&mmap_mutex);
}
}
void mmap_unlock(void)
{
if (--mmap_lock_count == 0) {
pthread_mutex_unlock(&mmap_mutex);
}
}
bool have_mmap_lock(void)
{
return mmap_lock_count > 0 ? true : false;
}
/* Grab lock to make sure things are in a consistent state after fork(). */
void mmap_fork_start(void)
{
if (mmap_lock_count)
abort();
pthread_mutex_lock(&mmap_mutex);
}
void mmap_fork_end(int child)
{
if (child)
pthread_mutex_init(&mmap_mutex, NULL);
else
pthread_mutex_unlock(&mmap_mutex);
}
/* NOTE: all the constants are the HOST ones, but addresses are target. */
int target_mprotect(abi_ulong start, abi_ulong len, int prot)
{
abi_ulong end, host_start, host_end, addr;
int prot1, ret;
#ifdef DEBUG_MMAP
printf("mprotect: start=0x" TARGET_FMT_lx
" len=0x" TARGET_FMT_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;
prot &= PROT_READ | PROT_WRITE | PROT_EXEC;
if (len == 0)
return 0;
mmap_lock();
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_untagged(host_start),
qemu_host_page_size, prot1 & PAGE_BITS);
if (ret != 0)
goto error;
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_untagged(host_end - qemu_host_page_size),
qemu_host_page_size, prot1 & PAGE_BITS);
if (ret != 0)
goto error;
host_end -= qemu_host_page_size;
}
/* handle the pages in the middle */
if (host_start < host_end) {
ret = mprotect(g2h_untagged(host_start), host_end - host_start, prot);
if (ret != 0)
goto error;
}
page_set_flags(start, start + len, prot | PAGE_VALID);
mmap_unlock();
return 0;
error:
mmap_unlock();
return ret;
}
/* map an incomplete host page */
static int mmap_frag(abi_ulong real_start,
abi_ulong start, abi_ulong end,
int prot, int flags, int fd, abi_ulong offset)
{
abi_ulong real_end, addr;
void *host_start;
int prot1, prot_new;
real_end = real_start + qemu_host_page_size;
host_start = g2h_untagged(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 */
void *p = mmap(host_start, qemu_host_page_size, prot,
flags | MAP_ANON, -1, 0);
if (p == MAP_FAILED)
return -1;
prot1 = prot;
}
prot1 &= PAGE_BITS;
prot_new = prot | prot1;
if (!(flags & MAP_ANON)) {
/* msync() won't work here, so we return an error if write is
possible while it is a shared mapping */
if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
(prot & PROT_WRITE))
return -1;
/* 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_untagged(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;
}
static abi_ulong mmap_next_start = 0x40000000;
unsigned long last_brk;
/* find a free memory area of size 'size'. The search starts at
'start'. If 'start' == 0, then a default start address is used.
Return -1 if error.
*/
/* page_init() marks pages used by the host as reserved to be sure not
to use them. */
static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size)
{
abi_ulong addr, addr1, addr_start;
int prot;
unsigned long new_brk;
new_brk = (unsigned long)sbrk(0);
if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) {
/* This is a hack to catch the host allocating memory with brk().
If it uses mmap then we loose.
FIXME: We really want to avoid the host allocating memory in
the first place, and maybe leave some slack to avoid switching
to mmap. */
page_set_flags(last_brk & TARGET_PAGE_MASK,
TARGET_PAGE_ALIGN(new_brk),
PAGE_RESERVED);
}
last_brk = new_brk;
size = HOST_PAGE_ALIGN(size);
start = start & qemu_host_page_mask;
addr = start;
if (addr == 0)
addr = mmap_next_start;
addr_start = addr;
for(;;) {
prot = 0;
for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) {
prot |= page_get_flags(addr1);
}
if (prot == 0)
break;
addr += qemu_host_page_size;
/* we found nothing */
if (addr == addr_start)
return (abi_ulong)-1;
}
if (start == 0)
mmap_next_start = addr + size;
return addr;
}
/* NOTE: all the constants are the HOST ones */
abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
int flags, int fd, abi_ulong offset)
{
abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len;
unsigned long host_start;
mmap_lock();
#ifdef DEBUG_MMAP
{
printf("mmap: start=0x" TARGET_FMT_lx
" len=0x" TARGET_FMT_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_ANON)
printf("MAP_ANON ");
switch(flags & TARGET_BSD_MAP_FLAGMASK) {
case MAP_PRIVATE:
printf("MAP_PRIVATE ");
break;
case MAP_SHARED:
printf("MAP_SHARED ");
break;
default:
printf("[MAP_FLAGMASK=0x%x] ", flags & TARGET_BSD_MAP_FLAGMASK);
break;
}
printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset);
}
#endif
if (offset & ~TARGET_PAGE_MASK) {
errno = EINVAL;
goto fail;
}
len = TARGET_PAGE_ALIGN(len);
if (len == 0)
goto the_end;
real_start = start & qemu_host_page_mask;
if (!(flags & MAP_FIXED)) {
abi_ulong mmap_start;
void *p;
host_offset = offset & qemu_host_page_mask;
host_len = len + offset - host_offset;
host_len = HOST_PAGE_ALIGN(host_len);
mmap_start = mmap_find_vma(real_start, host_len);
if (mmap_start == (abi_ulong)-1) {
errno = ENOMEM;
goto fail;
}
/* Note: we prefer to control the mapping address. It is
especially important if qemu_host_page_size >
qemu_real_host_page_size */
p = mmap(g2h_untagged(mmap_start),
host_len, prot, flags | MAP_FIXED, fd, host_offset);
if (p == MAP_FAILED)
goto fail;
/* update start so that it points to the file position at 'offset' */
host_start = (unsigned long)p;
if (!(flags & MAP_ANON))
host_start += offset - host_offset;
start = h2g(host_start);
} else {
int flg;
target_ulong addr;
if (start & ~TARGET_PAGE_MASK) {
errno = EINVAL;
goto fail;
}
end = start + len;
real_end = HOST_PAGE_ALIGN(end);
for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) {
flg = page_get_flags(addr);
if (flg & PAGE_RESERVED) {
errno = ENXIO;
goto fail;
}
}
/* worst case: we cannot map the file because the offset is not
aligned, so we read it */
if (!(flags & MAP_ANON) &&
(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 & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
(prot & PROT_WRITE)) {
errno = EINVAL;
goto fail;
}
retaddr = target_mmap(start, len, prot | PROT_WRITE,
MAP_FIXED | MAP_PRIVATE | MAP_ANON,
-1, 0);
if (retaddr == -1)
goto fail;
pread(fd, g2h_untagged(start), len, offset);
if (!(prot & PROT_WRITE)) {
ret = target_mprotect(start, len, prot);
if (ret != 0) {
start = ret;
goto the_end;
}
}
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)
goto fail;
goto the_end1;
}
ret = mmap_frag(real_start, start, real_start + qemu_host_page_size,
prot, flags, fd, offset);
if (ret == -1)
goto fail;
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)
goto fail;
real_end -= qemu_host_page_size;
}
/* map the middle (easier) */
if (real_start < real_end) {
void *p;
unsigned long offset1;
if (flags & MAP_ANON)
offset1 = 0;
else
offset1 = offset + real_start - start;
p = mmap(g2h_untagged(real_start), real_end - real_start,
prot, flags, fd, offset1);
if (p == MAP_FAILED)
goto fail;
}
}
the_end1:
page_set_flags(start, start + len, prot | PAGE_VALID);
the_end:
#ifdef DEBUG_MMAP
printf("ret=0x" TARGET_FMT_lx "\n", start);
page_dump(stdout);
printf("\n");
#endif
mmap_unlock();
return start;
fail:
mmap_unlock();
return -1;
}
int target_munmap(abi_ulong start, abi_ulong len)
{
abi_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;
mmap_lock();
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;
}
ret = 0;
/* unmap what we can */
if (real_start < real_end) {
ret = munmap(g2h_untagged(real_start), real_end - real_start);
}
if (ret == 0)
page_set_flags(start, start + len, 0);
mmap_unlock();
return ret;
}
int target_msync(abi_ulong start, abi_ulong len, int flags)
{
abi_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_untagged(start), end - start, flags);
}
