2
* mmap support for qemu
4
* Copyright (c) 2003 - 2008 Fabrice Bellard
6
* This program is free software; you can redistribute it and/or modify
7
* it under the terms of the GNU General Public License as published by
8
* the Free Software Foundation; either version 2 of the License, or
9
* (at your option) any later version.
11
* This program is distributed in the hope that it will be useful,
12
* but WITHOUT ANY WARRANTY; without even the implied warranty of
13
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14
* GNU General Public License for more details.
16
* You should have received a copy of the GNU General Public License
17
* along with this program; if not, write to the Free Software
18
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
29
#include "qemu-common.h"
34
pthread_mutex_t mmap_mutex;
35
static int __thread mmap_lock_count;
39
if (mmap_lock_count++ == 0) {
40
pthread_mutex_lock(&mmap_mutex);
44
void mmap_unlock(void)
46
if (--mmap_lock_count == 0) {
47
pthread_mutex_unlock(&mmap_mutex);
51
/* Grab lock to make sure things are in a consistent state after fork(). */
52
void mmap_fork_start(void)
56
pthread_mutex_lock(&mmap_mutex);
59
void mmap_fork_end(int child)
62
pthread_mutex_init(&mmap_mutex, NULL);
64
pthread_mutex_unlock(&mmap_mutex);
67
/* We aren't threadsafe to start with, so no need to worry about locking. */
72
void mmap_unlock(void)
77
void *qemu_vmalloc(size_t size)
82
/* Use map and mark the pages as used. */
83
p = mmap(NULL, size, PROT_READ | PROT_WRITE,
84
MAP_PRIVATE | MAP_ANON, -1, 0);
86
addr = (unsigned long)p;
87
if (addr == (target_ulong) addr) {
88
/* Allocated region overlaps guest address space.
90
page_set_flags(addr & TARGET_PAGE_MASK, TARGET_PAGE_ALIGN(addr + size),
98
void *qemu_malloc(size_t size)
102
p = qemu_vmalloc(size);
107
/* We use map, which is always zero initialized. */
108
void * qemu_mallocz(size_t size)
110
return qemu_malloc(size);
113
void qemu_free(void *ptr)
115
/* FIXME: We should unmark the reserved pages here. However this gets
116
complicated when one target page spans multiple host pages, so we
119
p = (size_t *)((char *)ptr - 16);
123
/* NOTE: all the constants are the HOST ones, but addresses are target. */
124
int target_mprotect(abi_ulong start, abi_ulong len, int prot)
126
abi_ulong end, host_start, host_end, addr;
130
printf("mprotect: start=0x" TARGET_FMT_lx
131
" len=0x" TARGET_FMT_lx " prot=%c%c%c\n", start, len,
132
prot & PROT_READ ? 'r' : '-',
133
prot & PROT_WRITE ? 'w' : '-',
134
prot & PROT_EXEC ? 'x' : '-');
137
if ((start & ~TARGET_PAGE_MASK) != 0)
139
len = TARGET_PAGE_ALIGN(len);
143
prot &= PROT_READ | PROT_WRITE | PROT_EXEC;
148
host_start = start & qemu_host_page_mask;
149
host_end = HOST_PAGE_ALIGN(end);
150
if (start > host_start) {
151
/* handle host page containing start */
153
for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
154
prot1 |= page_get_flags(addr);
156
if (host_end == host_start + qemu_host_page_size) {
157
for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
158
prot1 |= page_get_flags(addr);
162
ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS);
165
host_start += qemu_host_page_size;
167
if (end < host_end) {
169
for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
170
prot1 |= page_get_flags(addr);
172
ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size,
176
host_end -= qemu_host_page_size;
179
/* handle the pages in the middle */
180
if (host_start < host_end) {
181
ret = mprotect(g2h(host_start), host_end - host_start, prot);
185
page_set_flags(start, start + len, prot | PAGE_VALID);
193
/* map an incomplete host page */
194
static int mmap_frag(abi_ulong real_start,
195
abi_ulong start, abi_ulong end,
196
int prot, int flags, int fd, abi_ulong offset)
198
abi_ulong real_end, addr;
202
real_end = real_start + qemu_host_page_size;
203
host_start = g2h(real_start);
205
/* get the protection of the target pages outside the mapping */
207
for(addr = real_start; addr < real_end; addr++) {
208
if (addr < start || addr >= end)
209
prot1 |= page_get_flags(addr);
213
/* no page was there, so we allocate one */
214
void *p = mmap(host_start, qemu_host_page_size, prot,
215
flags | MAP_ANON, -1, 0);
222
prot_new = prot | prot1;
223
if (!(flags & MAP_ANON)) {
224
/* msync() won't work here, so we return an error if write is
225
possible while it is a shared mapping */
226
if ((flags & MAP_FLAGMASK) == MAP_SHARED &&
230
/* adjust protection to be able to read */
231
if (!(prot1 & PROT_WRITE))
232
mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE);
234
/* read the corresponding file data */
235
pread(fd, g2h(start), end - start, offset);
237
/* put final protection */
238
if (prot_new != (prot1 | PROT_WRITE))
239
mprotect(host_start, qemu_host_page_size, prot_new);
241
/* just update the protection */
242
if (prot_new != prot1) {
243
mprotect(host_start, qemu_host_page_size, prot_new);
249
#if defined(__CYGWIN__)
250
/* Cygwin doesn't have a whole lot of address space. */
251
static abi_ulong mmap_next_start = 0x18000000;
253
static abi_ulong mmap_next_start = 0x40000000;
256
unsigned long last_brk;
258
/* find a free memory area of size 'size'. The search starts at
259
'start'. If 'start' == 0, then a default start address is used.
262
/* page_init() marks pages used by the host as reserved to be sure not
264
static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size)
266
abi_ulong addr, addr1, addr_start;
268
unsigned long new_brk;
270
new_brk = (unsigned long)sbrk(0);
271
if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) {
272
/* This is a hack to catch the host allocating memory with brk().
273
If it uses mmap then we loose.
274
FIXME: We really want to avoid the host allocating memory in
275
the first place, and maybe leave some slack to avoid switching
277
page_set_flags(last_brk & TARGET_PAGE_MASK,
278
TARGET_PAGE_ALIGN(new_brk),
283
size = HOST_PAGE_ALIGN(size);
284
start = start & qemu_host_page_mask;
287
addr = mmap_next_start;
291
for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) {
292
prot |= page_get_flags(addr1);
296
addr += qemu_host_page_size;
297
/* we found nothing */
298
if (addr == addr_start)
299
return (abi_ulong)-1;
302
mmap_next_start = addr + size;
306
/* NOTE: all the constants are the HOST ones */
307
abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
308
int flags, int fd, abi_ulong offset)
310
abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len;
311
unsigned long host_start;
316
printf("mmap: start=0x" TARGET_FMT_lx
317
" len=0x" TARGET_FMT_lx " prot=%c%c%c flags=",
319
prot & PROT_READ ? 'r' : '-',
320
prot & PROT_WRITE ? 'w' : '-',
321
prot & PROT_EXEC ? 'x' : '-');
322
if (flags & MAP_FIXED)
323
printf("MAP_FIXED ");
324
if (flags & MAP_ANON)
326
switch(flags & MAP_FLAGMASK) {
328
printf("MAP_PRIVATE ");
331
printf("MAP_SHARED ");
334
printf("[MAP_FLAGMASK=0x%x] ", flags & MAP_FLAGMASK);
337
printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset);
341
if (offset & ~TARGET_PAGE_MASK) {
346
len = TARGET_PAGE_ALIGN(len);
349
real_start = start & qemu_host_page_mask;
351
if (!(flags & MAP_FIXED)) {
352
abi_ulong mmap_start;
354
host_offset = offset & qemu_host_page_mask;
355
host_len = len + offset - host_offset;
356
host_len = HOST_PAGE_ALIGN(host_len);
357
mmap_start = mmap_find_vma(real_start, host_len);
358
if (mmap_start == (abi_ulong)-1) {
362
/* Note: we prefer to control the mapping address. It is
363
especially important if qemu_host_page_size >
364
qemu_real_host_page_size */
365
p = mmap(g2h(mmap_start),
366
host_len, prot, flags | MAP_FIXED, fd, host_offset);
369
/* update start so that it points to the file position at 'offset' */
370
host_start = (unsigned long)p;
371
if (!(flags & MAP_ANON))
372
host_start += offset - host_offset;
373
start = h2g(host_start);
378
if (start & ~TARGET_PAGE_MASK) {
383
real_end = HOST_PAGE_ALIGN(end);
385
for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) {
386
flg = page_get_flags(addr);
387
if (flg & PAGE_RESERVED) {
393
/* worst case: we cannot map the file because the offset is not
394
aligned, so we read it */
395
if (!(flags & MAP_ANON) &&
396
(offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) {
397
/* msync() won't work here, so we return an error if write is
398
possible while it is a shared mapping */
399
if ((flags & MAP_FLAGMASK) == MAP_SHARED &&
400
(prot & PROT_WRITE)) {
404
retaddr = target_mmap(start, len, prot | PROT_WRITE,
405
MAP_FIXED | MAP_PRIVATE | MAP_ANON,
409
pread(fd, g2h(start), len, offset);
410
if (!(prot & PROT_WRITE)) {
411
ret = target_mprotect(start, len, prot);
420
/* handle the start of the mapping */
421
if (start > real_start) {
422
if (real_end == real_start + qemu_host_page_size) {
423
/* one single host page */
424
ret = mmap_frag(real_start, start, end,
425
prot, flags, fd, offset);
430
ret = mmap_frag(real_start, start, real_start + qemu_host_page_size,
431
prot, flags, fd, offset);
434
real_start += qemu_host_page_size;
436
/* handle the end of the mapping */
437
if (end < real_end) {
438
ret = mmap_frag(real_end - qemu_host_page_size,
439
real_end - qemu_host_page_size, real_end,
441
offset + real_end - qemu_host_page_size - start);
444
real_end -= qemu_host_page_size;
447
/* map the middle (easier) */
448
if (real_start < real_end) {
450
unsigned long offset1;
451
if (flags & MAP_ANON)
454
offset1 = offset + real_start - start;
455
p = mmap(g2h(real_start), real_end - real_start,
456
prot, flags, fd, offset1);
462
page_set_flags(start, start + len, prot | PAGE_VALID);
465
printf("ret=0x" TARGET_FMT_lx "\n", start);
476
int target_munmap(abi_ulong start, abi_ulong len)
478
abi_ulong end, real_start, real_end, addr;
482
printf("munmap: start=0x%lx len=0x%lx\n", start, len);
484
if (start & ~TARGET_PAGE_MASK)
486
len = TARGET_PAGE_ALIGN(len);
491
real_start = start & qemu_host_page_mask;
492
real_end = HOST_PAGE_ALIGN(end);
494
if (start > real_start) {
495
/* handle host page containing start */
497
for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) {
498
prot |= page_get_flags(addr);
500
if (real_end == real_start + qemu_host_page_size) {
501
for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
502
prot |= page_get_flags(addr);
507
real_start += qemu_host_page_size;
509
if (end < real_end) {
511
for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
512
prot |= page_get_flags(addr);
515
real_end -= qemu_host_page_size;
519
/* unmap what we can */
520
if (real_start < real_end) {
521
ret = munmap(g2h(real_start), real_end - real_start);
525
page_set_flags(start, start + len, 0);
530
int target_msync(abi_ulong start, abi_ulong len, int flags)
534
if (start & ~TARGET_PAGE_MASK)
536
len = TARGET_PAGE_ALIGN(len);
543
start &= qemu_host_page_mask;
544
return msync(g2h(start), end - start, flags);
added
removed
bsd-user/mmap.c
