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84778508
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1/*
2 * mmap support for qemu
3 *
4 * Copyright (c) 2003 - 2008 Fabrice Bellard
5 *
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.
10 *
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.
15 *
16 * You should have received a copy of the GNU General Public License
8167ee88 17 * along with this program; if not, see <http://www.gnu.org/licenses/>.
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18 */
19#include <stdlib.h>
20#include <stdio.h>
21#include <stdarg.h>
22#include <string.h>
23#include <unistd.h>
24#include <errno.h>
25#include <sys/mman.h>
26
27#include "qemu.h"
28#include "qemu-common.h"
6c173b3c 29#include "bsd-mman.h"
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30
31//#define DEBUG_MMAP
32
2f7bb878 33#if defined(CONFIG_USE_NPTL)
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34pthread_mutex_t mmap_mutex;
35static int __thread mmap_lock_count;
36
37void mmap_lock(void)
38{
39 if (mmap_lock_count++ == 0) {
40 pthread_mutex_lock(&mmap_mutex);
41 }
42}
43
44void mmap_unlock(void)
45{
46 if (--mmap_lock_count == 0) {
47 pthread_mutex_unlock(&mmap_mutex);
48 }
49}
50
51/* Grab lock to make sure things are in a consistent state after fork(). */
52void mmap_fork_start(void)
53{
54 if (mmap_lock_count)
55 abort();
56 pthread_mutex_lock(&mmap_mutex);
57}
58
59void mmap_fork_end(int child)
60{
61 if (child)
62 pthread_mutex_init(&mmap_mutex, NULL);
63 else
64 pthread_mutex_unlock(&mmap_mutex);
65}
66#else
67/* We aren't threadsafe to start with, so no need to worry about locking. */
68void mmap_lock(void)
69{
70}
71
72void mmap_unlock(void)
73{
74}
75#endif
76
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77/* NOTE: all the constants are the HOST ones, but addresses are target. */
78int target_mprotect(abi_ulong start, abi_ulong len, int prot)
79{
80 abi_ulong end, host_start, host_end, addr;
81 int prot1, ret;
82
83#ifdef DEBUG_MMAP
84 printf("mprotect: start=0x" TARGET_FMT_lx
85 " len=0x" TARGET_FMT_lx " prot=%c%c%c\n", start, len,
86 prot & PROT_READ ? 'r' : '-',
87 prot & PROT_WRITE ? 'w' : '-',
88 prot & PROT_EXEC ? 'x' : '-');
89#endif
90
91 if ((start & ~TARGET_PAGE_MASK) != 0)
92 return -EINVAL;
93 len = TARGET_PAGE_ALIGN(len);
94 end = start + len;
95 if (end < start)
96 return -EINVAL;
97 prot &= PROT_READ | PROT_WRITE | PROT_EXEC;
98 if (len == 0)
99 return 0;
100
101 mmap_lock();
102 host_start = start & qemu_host_page_mask;
103 host_end = HOST_PAGE_ALIGN(end);
104 if (start > host_start) {
105 /* handle host page containing start */
106 prot1 = prot;
107 for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
108 prot1 |= page_get_flags(addr);
109 }
110 if (host_end == host_start + qemu_host_page_size) {
111 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
112 prot1 |= page_get_flags(addr);
113 }
114 end = host_end;
115 }
116 ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS);
117 if (ret != 0)
118 goto error;
119 host_start += qemu_host_page_size;
120 }
121 if (end < host_end) {
122 prot1 = prot;
123 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
124 prot1 |= page_get_flags(addr);
125 }
126 ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size,
127 prot1 & PAGE_BITS);
128 if (ret != 0)
129 goto error;
130 host_end -= qemu_host_page_size;
131 }
132
133 /* handle the pages in the middle */
134 if (host_start < host_end) {
135 ret = mprotect(g2h(host_start), host_end - host_start, prot);
136 if (ret != 0)
137 goto error;
138 }
139 page_set_flags(start, start + len, prot | PAGE_VALID);
140 mmap_unlock();
141 return 0;
142error:
143 mmap_unlock();
144 return ret;
145}
146
147/* map an incomplete host page */
148static int mmap_frag(abi_ulong real_start,
149 abi_ulong start, abi_ulong end,
150 int prot, int flags, int fd, abi_ulong offset)
151{
152 abi_ulong real_end, addr;
153 void *host_start;
154 int prot1, prot_new;
155
156 real_end = real_start + qemu_host_page_size;
157 host_start = g2h(real_start);
158
159 /* get the protection of the target pages outside the mapping */
160 prot1 = 0;
161 for(addr = real_start; addr < real_end; addr++) {
162 if (addr < start || addr >= end)
163 prot1 |= page_get_flags(addr);
164 }
165
166 if (prot1 == 0) {
167 /* no page was there, so we allocate one */
168 void *p = mmap(host_start, qemu_host_page_size, prot,
169 flags | MAP_ANON, -1, 0);
170 if (p == MAP_FAILED)
171 return -1;
172 prot1 = prot;
173 }
174 prot1 &= PAGE_BITS;
175
176 prot_new = prot | prot1;
177 if (!(flags & MAP_ANON)) {
178 /* msync() won't work here, so we return an error if write is
179 possible while it is a shared mapping */
6c173b3c 180 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
84778508 181 (prot & PROT_WRITE))
059bca46 182 return -1;
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183
184 /* adjust protection to be able to read */
185 if (!(prot1 & PROT_WRITE))
186 mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE);
187
188 /* read the corresponding file data */
189 pread(fd, g2h(start), end - start, offset);
190
191 /* put final protection */
192 if (prot_new != (prot1 | PROT_WRITE))
193 mprotect(host_start, qemu_host_page_size, prot_new);
194 } else {
195 /* just update the protection */
196 if (prot_new != prot1) {
197 mprotect(host_start, qemu_host_page_size, prot_new);
198 }
199 }
200 return 0;
201}
202
203#if defined(__CYGWIN__)
204/* Cygwin doesn't have a whole lot of address space. */
205static abi_ulong mmap_next_start = 0x18000000;
206#else
207static abi_ulong mmap_next_start = 0x40000000;
208#endif
209
210unsigned long last_brk;
211
212/* find a free memory area of size 'size'. The search starts at
213 'start'. If 'start' == 0, then a default start address is used.
214 Return -1 if error.
215*/
216/* page_init() marks pages used by the host as reserved to be sure not
217 to use them. */
218static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size)
219{
220 abi_ulong addr, addr1, addr_start;
221 int prot;
222 unsigned long new_brk;
223
224 new_brk = (unsigned long)sbrk(0);
225 if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) {
226 /* This is a hack to catch the host allocating memory with brk().
227 If it uses mmap then we loose.
228 FIXME: We really want to avoid the host allocating memory in
229 the first place, and maybe leave some slack to avoid switching
230 to mmap. */
231 page_set_flags(last_brk & TARGET_PAGE_MASK,
232 TARGET_PAGE_ALIGN(new_brk),
233 PAGE_RESERVED);
234 }
235 last_brk = new_brk;
236
237 size = HOST_PAGE_ALIGN(size);
238 start = start & qemu_host_page_mask;
239 addr = start;
240 if (addr == 0)
241 addr = mmap_next_start;
242 addr_start = addr;
243 for(;;) {
244 prot = 0;
245 for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) {
246 prot |= page_get_flags(addr1);
247 }
248 if (prot == 0)
249 break;
250 addr += qemu_host_page_size;
251 /* we found nothing */
252 if (addr == addr_start)
253 return (abi_ulong)-1;
254 }
255 if (start == 0)
256 mmap_next_start = addr + size;
257 return addr;
258}
259
260/* NOTE: all the constants are the HOST ones */
261abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
262 int flags, int fd, abi_ulong offset)
263{
264 abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len;
265 unsigned long host_start;
266
267 mmap_lock();
268#ifdef DEBUG_MMAP
269 {
270 printf("mmap: start=0x" TARGET_FMT_lx
271 " len=0x" TARGET_FMT_lx " prot=%c%c%c flags=",
272 start, len,
273 prot & PROT_READ ? 'r' : '-',
274 prot & PROT_WRITE ? 'w' : '-',
275 prot & PROT_EXEC ? 'x' : '-');
276 if (flags & MAP_FIXED)
277 printf("MAP_FIXED ");
278 if (flags & MAP_ANON)
279 printf("MAP_ANON ");
6c173b3c 280 switch(flags & TARGET_BSD_MAP_FLAGMASK) {
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281 case MAP_PRIVATE:
282 printf("MAP_PRIVATE ");
283 break;
284 case MAP_SHARED:
285 printf("MAP_SHARED ");
286 break;
287 default:
6c173b3c 288 printf("[MAP_FLAGMASK=0x%x] ", flags & TARGET_BSD_MAP_FLAGMASK);
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289 break;
290 }
291 printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset);
292 }
293#endif
294
295 if (offset & ~TARGET_PAGE_MASK) {
296 errno = EINVAL;
297 goto fail;
298 }
299
300 len = TARGET_PAGE_ALIGN(len);
301 if (len == 0)
302 goto the_end;
303 real_start = start & qemu_host_page_mask;
304
305 if (!(flags & MAP_FIXED)) {
306 abi_ulong mmap_start;
307 void *p;
308 host_offset = offset & qemu_host_page_mask;
309 host_len = len + offset - host_offset;
310 host_len = HOST_PAGE_ALIGN(host_len);
311 mmap_start = mmap_find_vma(real_start, host_len);
312 if (mmap_start == (abi_ulong)-1) {
313 errno = ENOMEM;
314 goto fail;
315 }
316 /* Note: we prefer to control the mapping address. It is
317 especially important if qemu_host_page_size >
318 qemu_real_host_page_size */
319 p = mmap(g2h(mmap_start),
320 host_len, prot, flags | MAP_FIXED, fd, host_offset);
321 if (p == MAP_FAILED)
322 goto fail;
323 /* update start so that it points to the file position at 'offset' */
324 host_start = (unsigned long)p;
325 if (!(flags & MAP_ANON))
326 host_start += offset - host_offset;
327 start = h2g(host_start);
328 } else {
329 int flg;
330 target_ulong addr;
331
332 if (start & ~TARGET_PAGE_MASK) {
333 errno = EINVAL;
334 goto fail;
335 }
336 end = start + len;
337 real_end = HOST_PAGE_ALIGN(end);
338
339 for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) {
340 flg = page_get_flags(addr);
341 if (flg & PAGE_RESERVED) {
342 errno = ENXIO;
343 goto fail;
344 }
345 }
346
347 /* worst case: we cannot map the file because the offset is not
348 aligned, so we read it */
349 if (!(flags & MAP_ANON) &&
350 (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) {
351 /* msync() won't work here, so we return an error if write is
352 possible while it is a shared mapping */
6c173b3c 353 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
84778508
BS
354 (prot & PROT_WRITE)) {
355 errno = EINVAL;
356 goto fail;
357 }
358 retaddr = target_mmap(start, len, prot | PROT_WRITE,
359 MAP_FIXED | MAP_PRIVATE | MAP_ANON,
360 -1, 0);
361 if (retaddr == -1)
362 goto fail;
363 pread(fd, g2h(start), len, offset);
364 if (!(prot & PROT_WRITE)) {
365 ret = target_mprotect(start, len, prot);
366 if (ret != 0) {
367 start = ret;
368 goto the_end;
369 }
370 }
371 goto the_end;
372 }
373
374 /* handle the start of the mapping */
375 if (start > real_start) {
376 if (real_end == real_start + qemu_host_page_size) {
377 /* one single host page */
378 ret = mmap_frag(real_start, start, end,
379 prot, flags, fd, offset);
380 if (ret == -1)
381 goto fail;
382 goto the_end1;
383 }
384 ret = mmap_frag(real_start, start, real_start + qemu_host_page_size,
385 prot, flags, fd, offset);
386 if (ret == -1)
387 goto fail;
388 real_start += qemu_host_page_size;
389 }
390 /* handle the end of the mapping */
391 if (end < real_end) {
392 ret = mmap_frag(real_end - qemu_host_page_size,
393 real_end - qemu_host_page_size, real_end,
394 prot, flags, fd,
395 offset + real_end - qemu_host_page_size - start);
396 if (ret == -1)
397 goto fail;
398 real_end -= qemu_host_page_size;
399 }
400
401 /* map the middle (easier) */
402 if (real_start < real_end) {
403 void *p;
404 unsigned long offset1;
405 if (flags & MAP_ANON)
406 offset1 = 0;
407 else
408 offset1 = offset + real_start - start;
409 p = mmap(g2h(real_start), real_end - real_start,
410 prot, flags, fd, offset1);
411 if (p == MAP_FAILED)
412 goto fail;
413 }
414 }
415 the_end1:
416 page_set_flags(start, start + len, prot | PAGE_VALID);
417 the_end:
418#ifdef DEBUG_MMAP
419 printf("ret=0x" TARGET_FMT_lx "\n", start);
420 page_dump(stdout);
421 printf("\n");
422#endif
423 mmap_unlock();
424 return start;
425fail:
426 mmap_unlock();
427 return -1;
428}
429
430int target_munmap(abi_ulong start, abi_ulong len)
431{
432 abi_ulong end, real_start, real_end, addr;
433 int prot, ret;
434
435#ifdef DEBUG_MMAP
436 printf("munmap: start=0x%lx len=0x%lx\n", start, len);
437#endif
438 if (start & ~TARGET_PAGE_MASK)
439 return -EINVAL;
440 len = TARGET_PAGE_ALIGN(len);
441 if (len == 0)
442 return -EINVAL;
443 mmap_lock();
444 end = start + len;
445 real_start = start & qemu_host_page_mask;
446 real_end = HOST_PAGE_ALIGN(end);
447
448 if (start > real_start) {
449 /* handle host page containing start */
450 prot = 0;
451 for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) {
452 prot |= page_get_flags(addr);
453 }
454 if (real_end == real_start + qemu_host_page_size) {
455 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
456 prot |= page_get_flags(addr);
457 }
458 end = real_end;
459 }
460 if (prot != 0)
461 real_start += qemu_host_page_size;
462 }
463 if (end < real_end) {
464 prot = 0;
465 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
466 prot |= page_get_flags(addr);
467 }
468 if (prot != 0)
469 real_end -= qemu_host_page_size;
470 }
471
472 ret = 0;
473 /* unmap what we can */
474 if (real_start < real_end) {
475 ret = munmap(g2h(real_start), real_end - real_start);
476 }
477
478 if (ret == 0)
479 page_set_flags(start, start + len, 0);
480 mmap_unlock();
481 return ret;
482}
483
484int target_msync(abi_ulong start, abi_ulong len, int flags)
485{
486 abi_ulong end;
487
488 if (start & ~TARGET_PAGE_MASK)
489 return -EINVAL;
490 len = TARGET_PAGE_ALIGN(len);
491 end = start + len;
492 if (end < start)
493 return -EINVAL;
494 if (end == start)
495 return 0;
496
497 start &= qemu_host_page_mask;
498 return msync(g2h(start), end - start, flags);
499}