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 17 * along with this program; if not, see <http://www.gnu.org/licenses/>. 18 */ 19 #include "qemu/osdep.h" 20 21 #include "qemu.h" 22 23 static pthread_mutex_t mmap_mutex = PTHREAD_MUTEX_INITIALIZER; 24 static __thread int mmap_lock_count; 25 26 void mmap_lock(void) 27 { 28 if (mmap_lock_count++ == 0) { 29 pthread_mutex_lock(&mmap_mutex); 30 } 31 } 32 33 void mmap_unlock(void) 34 { 35 assert(mmap_lock_count > 0); 36 if (--mmap_lock_count == 0) { 37 pthread_mutex_unlock(&mmap_mutex); 38 } 39 } 40 41 bool have_mmap_lock(void) 42 { 43 return mmap_lock_count > 0 ? true : false; 44 } 45 46 /* Grab lock to make sure things are in a consistent state after fork(). */ 47 void mmap_fork_start(void) 48 { 49 if (mmap_lock_count) 50 abort(); 51 pthread_mutex_lock(&mmap_mutex); 52 } 53 54 void mmap_fork_end(int child) 55 { 56 if (child) 57 pthread_mutex_init(&mmap_mutex, NULL); 58 else 59 pthread_mutex_unlock(&mmap_mutex); 60 } 61 62 /* NOTE: all the constants are the HOST ones, but addresses are target. */ 63 int target_mprotect(abi_ulong start, abi_ulong len, int prot) 64 { 65 abi_ulong end, host_start, host_end, addr; 66 int prot1, ret; 67 68 qemu_log_mask(CPU_LOG_PAGE, "mprotect: start=0x" TARGET_ABI_FMT_lx 69 " len=0x" TARGET_ABI_FMT_lx " prot=%c%c%c\n", start, len, 70 prot & PROT_READ ? 'r' : '-', 71 prot & PROT_WRITE ? 'w' : '-', 72 prot & PROT_EXEC ? 'x' : '-'); 73 if ((start & ~TARGET_PAGE_MASK) != 0) 74 return -EINVAL; 75 len = TARGET_PAGE_ALIGN(len); 76 end = start + len; 77 if (end < start) 78 return -EINVAL; 79 prot &= PROT_READ | PROT_WRITE | PROT_EXEC; 80 if (len == 0) 81 return 0; 82 83 mmap_lock(); 84 host_start = start & qemu_host_page_mask; 85 host_end = HOST_PAGE_ALIGN(end); 86 if (start > host_start) { 87 /* handle host page containing start */ 88 prot1 = prot; 89 for (addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) { 90 prot1 |= page_get_flags(addr); 91 } 92 if (host_end == host_start + qemu_host_page_size) { 93 for (addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 94 prot1 |= page_get_flags(addr); 95 } 96 end = host_end; 97 } 98 ret = mprotect(g2h_untagged(host_start), 99 qemu_host_page_size, prot1 & PAGE_BITS); 100 if (ret != 0) 101 goto error; 102 host_start += qemu_host_page_size; 103 } 104 if (end < host_end) { 105 prot1 = prot; 106 for (addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 107 prot1 |= page_get_flags(addr); 108 } 109 ret = mprotect(g2h_untagged(host_end - qemu_host_page_size), 110 qemu_host_page_size, prot1 & PAGE_BITS); 111 if (ret != 0) 112 goto error; 113 host_end -= qemu_host_page_size; 114 } 115 116 /* handle the pages in the middle */ 117 if (host_start < host_end) { 118 ret = mprotect(g2h_untagged(host_start), host_end - host_start, prot); 119 if (ret != 0) 120 goto error; 121 } 122 page_set_flags(start, start + len - 1, prot | PAGE_VALID); 123 mmap_unlock(); 124 return 0; 125 error: 126 mmap_unlock(); 127 return ret; 128 } 129 130 /* 131 * map an incomplete host page 132 * 133 * mmap_frag can be called with a valid fd, if flags doesn't contain one of 134 * MAP_ANON, MAP_STACK, MAP_GUARD. If we need to map a page in those cases, we 135 * pass fd == -1. However, if flags contains MAP_GUARD then MAP_ANON cannot be 136 * added. 137 * 138 * * If fd is valid (not -1) we want to map the pages with MAP_ANON. 139 * * If flags contains MAP_GUARD we don't want to add MAP_ANON because it 140 * will be rejected. See kern_mmap's enforcing of constraints for MAP_GUARD 141 * in sys/vm/vm_mmap.c. 142 * * If flags contains MAP_ANON it doesn't matter if we add it or not. 143 * * If flags contains MAP_STACK, mmap adds MAP_ANON when called so doesn't 144 * matter if we add it or not either. See enforcing of constraints for 145 * MAP_STACK in kern_mmap. 146 * 147 * Don't add MAP_ANON for the flags that use fd == -1 without specifying the 148 * flags directly, with the assumption that future flags that require fd == -1 149 * will also not require MAP_ANON. 150 */ 151 static int mmap_frag(abi_ulong real_start, 152 abi_ulong start, abi_ulong end, 153 int prot, int flags, int fd, abi_ulong offset) 154 { 155 abi_ulong real_end, addr; 156 void *host_start; 157 int prot1, prot_new; 158 159 real_end = real_start + qemu_host_page_size; 160 host_start = g2h_untagged(real_start); 161 162 /* get the protection of the target pages outside the mapping */ 163 prot1 = 0; 164 for (addr = real_start; addr < real_end; addr++) { 165 if (addr < start || addr >= end) 166 prot1 |= page_get_flags(addr); 167 } 168 169 if (prot1 == 0) { 170 /* no page was there, so we allocate one. See also above. */ 171 void *p = mmap(host_start, qemu_host_page_size, prot, 172 flags | ((fd != -1) ? MAP_ANON : 0), -1, 0); 173 if (p == MAP_FAILED) 174 return -1; 175 prot1 = prot; 176 } 177 prot1 &= PAGE_BITS; 178 179 prot_new = prot | prot1; 180 if (fd != -1) { 181 /* msync() won't work here, so we return an error if write is 182 possible while it is a shared mapping */ 183 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && 184 (prot & PROT_WRITE)) 185 return -1; 186 187 /* adjust protection to be able to read */ 188 if (!(prot1 & PROT_WRITE)) 189 mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE); 190 191 /* read the corresponding file data */ 192 if (pread(fd, g2h_untagged(start), end - start, offset) == -1) { 193 return -1; 194 } 195 196 /* put final protection */ 197 if (prot_new != (prot1 | PROT_WRITE)) 198 mprotect(host_start, qemu_host_page_size, prot_new); 199 } else { 200 if (prot_new != prot1) { 201 mprotect(host_start, qemu_host_page_size, prot_new); 202 } 203 if (prot_new & PROT_WRITE) { 204 memset(g2h_untagged(start), 0, end - start); 205 } 206 } 207 return 0; 208 } 209 210 #if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64 211 # define TASK_UNMAPPED_BASE (1ul << 38) 212 #else 213 # define TASK_UNMAPPED_BASE 0x40000000 214 #endif 215 abi_ulong mmap_next_start = TASK_UNMAPPED_BASE; 216 217 /* 218 * Subroutine of mmap_find_vma, used when we have pre-allocated a chunk of guest 219 * address space. 220 */ 221 static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, 222 abi_ulong alignment) 223 { 224 abi_ulong ret; 225 226 ret = page_find_range_empty(start, reserved_va, size, alignment); 227 if (ret == -1 && start > TARGET_PAGE_SIZE) { 228 /* Restart at the beginning of the address space. */ 229 ret = page_find_range_empty(TARGET_PAGE_SIZE, start - 1, 230 size, alignment); 231 } 232 233 return ret; 234 } 235 236 /* 237 * Find and reserve a free memory area of size 'size'. The search 238 * starts at 'start'. 239 * It must be called with mmap_lock() held. 240 * Return -1 if error. 241 */ 242 static abi_ulong mmap_find_vma_aligned(abi_ulong start, abi_ulong size, 243 abi_ulong alignment) 244 { 245 void *ptr, *prev; 246 abi_ulong addr; 247 int flags; 248 int wrapped, repeat; 249 250 /* If 'start' == 0, then a default start address is used. */ 251 if (start == 0) { 252 start = mmap_next_start; 253 } else { 254 start &= qemu_host_page_mask; 255 } 256 257 size = HOST_PAGE_ALIGN(size); 258 259 if (reserved_va) { 260 return mmap_find_vma_reserved(start, size, 261 (alignment != 0 ? 1 << alignment : 262 MAX(qemu_host_page_size, TARGET_PAGE_SIZE))); 263 } 264 265 addr = start; 266 wrapped = repeat = 0; 267 prev = 0; 268 flags = MAP_ANON | MAP_PRIVATE; 269 if (alignment != 0) { 270 flags |= MAP_ALIGNED(alignment); 271 } 272 273 for (;; prev = ptr) { 274 /* 275 * Reserve needed memory area to avoid a race. 276 * It should be discarded using: 277 * - mmap() with MAP_FIXED flag 278 * - mremap() with MREMAP_FIXED flag 279 * - shmat() with SHM_REMAP flag 280 */ 281 ptr = mmap(g2h_untagged(addr), size, PROT_NONE, 282 flags, -1, 0); 283 284 /* ENOMEM, if host address space has no memory */ 285 if (ptr == MAP_FAILED) { 286 return (abi_ulong)-1; 287 } 288 289 /* 290 * Count the number of sequential returns of the same address. 291 * This is used to modify the search algorithm below. 292 */ 293 repeat = (ptr == prev ? repeat + 1 : 0); 294 295 if (h2g_valid(ptr + size - 1)) { 296 addr = h2g(ptr); 297 298 if ((addr & ~TARGET_PAGE_MASK) == 0) { 299 /* Success. */ 300 if (start == mmap_next_start && addr >= TASK_UNMAPPED_BASE) { 301 mmap_next_start = addr + size; 302 } 303 return addr; 304 } 305 306 /* The address is not properly aligned for the target. */ 307 switch (repeat) { 308 case 0: 309 /* 310 * Assume the result that the kernel gave us is the 311 * first with enough free space, so start again at the 312 * next higher target page. 313 */ 314 addr = TARGET_PAGE_ALIGN(addr); 315 break; 316 case 1: 317 /* 318 * Sometimes the kernel decides to perform the allocation 319 * at the top end of memory instead. 320 */ 321 addr &= TARGET_PAGE_MASK; 322 break; 323 case 2: 324 /* Start over at low memory. */ 325 addr = 0; 326 break; 327 default: 328 /* Fail. This unaligned block must the last. */ 329 addr = -1; 330 break; 331 } 332 } else { 333 /* 334 * Since the result the kernel gave didn't fit, start 335 * again at low memory. If any repetition, fail. 336 */ 337 addr = (repeat ? -1 : 0); 338 } 339 340 /* Unmap and try again. */ 341 munmap(ptr, size); 342 343 /* ENOMEM if we checked the whole of the target address space. */ 344 if (addr == (abi_ulong)-1) { 345 return (abi_ulong)-1; 346 } else if (addr == 0) { 347 if (wrapped) { 348 return (abi_ulong)-1; 349 } 350 wrapped = 1; 351 /* 352 * Don't actually use 0 when wrapping, instead indicate 353 * that we'd truly like an allocation in low memory. 354 */ 355 addr = TARGET_PAGE_SIZE; 356 } else if (wrapped && addr >= start) { 357 return (abi_ulong)-1; 358 } 359 } 360 } 361 362 abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) 363 { 364 return mmap_find_vma_aligned(start, size, 0); 365 } 366 367 /* NOTE: all the constants are the HOST ones */ 368 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, 369 int flags, int fd, off_t offset) 370 { 371 abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; 372 373 mmap_lock(); 374 if (qemu_loglevel_mask(CPU_LOG_PAGE)) { 375 qemu_log("mmap: start=0x" TARGET_ABI_FMT_lx 376 " len=0x" TARGET_ABI_FMT_lx " prot=%c%c%c flags=", 377 start, len, 378 prot & PROT_READ ? 'r' : '-', 379 prot & PROT_WRITE ? 'w' : '-', 380 prot & PROT_EXEC ? 'x' : '-'); 381 if (flags & MAP_ALIGNMENT_MASK) { 382 qemu_log("MAP_ALIGNED(%u) ", 383 (flags & MAP_ALIGNMENT_MASK) >> MAP_ALIGNMENT_SHIFT); 384 } 385 if (flags & MAP_GUARD) { 386 qemu_log("MAP_GUARD "); 387 } 388 if (flags & MAP_FIXED) { 389 qemu_log("MAP_FIXED "); 390 } 391 if (flags & MAP_ANON) { 392 qemu_log("MAP_ANON "); 393 } 394 if (flags & MAP_EXCL) { 395 qemu_log("MAP_EXCL "); 396 } 397 if (flags & MAP_PRIVATE) { 398 qemu_log("MAP_PRIVATE "); 399 } 400 if (flags & MAP_SHARED) { 401 qemu_log("MAP_SHARED "); 402 } 403 if (flags & MAP_NOCORE) { 404 qemu_log("MAP_NOCORE "); 405 } 406 if (flags & MAP_STACK) { 407 qemu_log("MAP_STACK "); 408 } 409 qemu_log("fd=%d offset=0x%lx\n", fd, offset); 410 } 411 412 if ((flags & MAP_ANON) && fd != -1) { 413 errno = EINVAL; 414 goto fail; 415 } 416 if (flags & MAP_STACK) { 417 if ((fd != -1) || ((prot & (PROT_READ | PROT_WRITE)) != 418 (PROT_READ | PROT_WRITE))) { 419 errno = EINVAL; 420 goto fail; 421 } 422 } 423 if ((flags & MAP_GUARD) && (prot != PROT_NONE || fd != -1 || 424 offset != 0 || (flags & (MAP_SHARED | MAP_PRIVATE | 425 /* MAP_PREFAULT | */ /* MAP_PREFAULT not in mman.h */ 426 MAP_PREFAULT_READ | MAP_ANON | MAP_STACK)) != 0)) { 427 errno = EINVAL; 428 goto fail; 429 } 430 431 if (offset & ~TARGET_PAGE_MASK) { 432 errno = EINVAL; 433 goto fail; 434 } 435 436 if (len == 0) { 437 errno = EINVAL; 438 goto fail; 439 } 440 441 /* Check for overflows */ 442 len = TARGET_PAGE_ALIGN(len); 443 if (len == 0) { 444 errno = ENOMEM; 445 goto fail; 446 } 447 448 real_start = start & qemu_host_page_mask; 449 host_offset = offset & qemu_host_page_mask; 450 451 /* 452 * If the user is asking for the kernel to find a location, do that 453 * before we truncate the length for mapping files below. 454 */ 455 if (!(flags & MAP_FIXED)) { 456 host_len = len + offset - host_offset; 457 host_len = HOST_PAGE_ALIGN(host_len); 458 if ((flags & MAP_ALIGNMENT_MASK) != 0) 459 start = mmap_find_vma_aligned(real_start, host_len, 460 (flags & MAP_ALIGNMENT_MASK) >> MAP_ALIGNMENT_SHIFT); 461 else 462 start = mmap_find_vma(real_start, host_len); 463 if (start == (abi_ulong)-1) { 464 errno = ENOMEM; 465 goto fail; 466 } 467 } 468 469 /* 470 * When mapping files into a memory area larger than the file, accesses 471 * to pages beyond the file size will cause a SIGBUS. 472 * 473 * For example, if mmaping a file of 100 bytes on a host with 4K pages 474 * emulating a target with 8K pages, the target expects to be able to 475 * access the first 8K. But the host will trap us on any access beyond 476 * 4K. 477 * 478 * When emulating a target with a larger page-size than the hosts, we 479 * may need to truncate file maps at EOF and add extra anonymous pages 480 * up to the targets page boundary. 481 */ 482 483 if ((qemu_real_host_page_size() < qemu_host_page_size) && fd != -1) { 484 struct stat sb; 485 486 if (fstat(fd, &sb) == -1) { 487 goto fail; 488 } 489 490 /* Are we trying to create a map beyond EOF?. */ 491 if (offset + len > sb.st_size) { 492 /* 493 * If so, truncate the file map at eof aligned with 494 * the hosts real pagesize. Additional anonymous maps 495 * will be created beyond EOF. 496 */ 497 len = REAL_HOST_PAGE_ALIGN(sb.st_size - offset); 498 } 499 } 500 501 if (!(flags & MAP_FIXED)) { 502 unsigned long host_start; 503 void *p; 504 505 host_len = len + offset - host_offset; 506 host_len = HOST_PAGE_ALIGN(host_len); 507 508 /* 509 * Note: we prefer to control the mapping address. It is 510 * especially important if qemu_host_page_size > 511 * qemu_real_host_page_size 512 */ 513 p = mmap(g2h_untagged(start), host_len, prot, 514 flags | MAP_FIXED | ((fd != -1) ? MAP_ANON : 0), -1, 0); 515 if (p == MAP_FAILED) 516 goto fail; 517 /* update start so that it points to the file position at 'offset' */ 518 host_start = (unsigned long)p; 519 if (fd != -1) { 520 p = mmap(g2h_untagged(start), len, prot, 521 flags | MAP_FIXED, fd, host_offset); 522 if (p == MAP_FAILED) { 523 munmap(g2h_untagged(start), host_len); 524 goto fail; 525 } 526 host_start += offset - host_offset; 527 } 528 start = h2g(host_start); 529 } else { 530 if (start & ~TARGET_PAGE_MASK) { 531 errno = EINVAL; 532 goto fail; 533 } 534 end = start + len; 535 real_end = HOST_PAGE_ALIGN(end); 536 537 /* 538 * Test if requested memory area fits target address space 539 * It can fail only on 64-bit host with 32-bit target. 540 * On any other target/host host mmap() handles this error correctly. 541 */ 542 if (!guest_range_valid_untagged(start, len)) { 543 errno = EINVAL; 544 goto fail; 545 } 546 547 /* 548 * worst case: we cannot map the file because the offset is not 549 * aligned, so we read it 550 */ 551 if (fd != -1 && 552 (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) { 553 /* 554 * msync() won't work here, so we return an error if write is 555 * possible while it is a shared mapping 556 */ 557 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && 558 (prot & PROT_WRITE)) { 559 errno = EINVAL; 560 goto fail; 561 } 562 retaddr = target_mmap(start, len, prot | PROT_WRITE, 563 MAP_FIXED | MAP_PRIVATE | MAP_ANON, 564 -1, 0); 565 if (retaddr == -1) 566 goto fail; 567 if (pread(fd, g2h_untagged(start), len, offset) == -1) { 568 goto fail; 569 } 570 if (!(prot & PROT_WRITE)) { 571 ret = target_mprotect(start, len, prot); 572 assert(ret == 0); 573 } 574 goto the_end; 575 } 576 577 /* Reject the mapping if any page within the range is mapped */ 578 if ((flags & MAP_EXCL) && !page_check_range_empty(start, end - 1)) { 579 errno = EINVAL; 580 goto fail; 581 } 582 583 /* handle the start of the mapping */ 584 if (start > real_start) { 585 if (real_end == real_start + qemu_host_page_size) { 586 /* one single host page */ 587 ret = mmap_frag(real_start, start, end, 588 prot, flags, fd, offset); 589 if (ret == -1) 590 goto fail; 591 goto the_end1; 592 } 593 ret = mmap_frag(real_start, start, real_start + qemu_host_page_size, 594 prot, flags, fd, offset); 595 if (ret == -1) 596 goto fail; 597 real_start += qemu_host_page_size; 598 } 599 /* handle the end of the mapping */ 600 if (end < real_end) { 601 ret = mmap_frag(real_end - qemu_host_page_size, 602 real_end - qemu_host_page_size, end, 603 prot, flags, fd, 604 offset + real_end - qemu_host_page_size - start); 605 if (ret == -1) 606 goto fail; 607 real_end -= qemu_host_page_size; 608 } 609 610 /* map the middle (easier) */ 611 if (real_start < real_end) { 612 void *p; 613 unsigned long offset1; 614 if (flags & MAP_ANON) 615 offset1 = 0; 616 else 617 offset1 = offset + real_start - start; 618 p = mmap(g2h_untagged(real_start), real_end - real_start, 619 prot, flags, fd, offset1); 620 if (p == MAP_FAILED) 621 goto fail; 622 } 623 } 624 the_end1: 625 page_set_flags(start, start + len - 1, prot | PAGE_VALID); 626 the_end: 627 #ifdef DEBUG_MMAP 628 printf("ret=0x" TARGET_ABI_FMT_lx "\n", start); 629 page_dump(stdout); 630 printf("\n"); 631 #endif 632 mmap_unlock(); 633 return start; 634 fail: 635 mmap_unlock(); 636 return -1; 637 } 638 639 static void mmap_reserve(abi_ulong start, abi_ulong size) 640 { 641 abi_ulong real_start; 642 abi_ulong real_end; 643 abi_ulong addr; 644 abi_ulong end; 645 int prot; 646 647 real_start = start & qemu_host_page_mask; 648 real_end = HOST_PAGE_ALIGN(start + size); 649 end = start + size; 650 if (start > real_start) { 651 /* handle host page containing start */ 652 prot = 0; 653 for (addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { 654 prot |= page_get_flags(addr); 655 } 656 if (real_end == real_start + qemu_host_page_size) { 657 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 658 prot |= page_get_flags(addr); 659 } 660 end = real_end; 661 } 662 if (prot != 0) { 663 real_start += qemu_host_page_size; 664 } 665 } 666 if (end < real_end) { 667 prot = 0; 668 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 669 prot |= page_get_flags(addr); 670 } 671 if (prot != 0) { 672 real_end -= qemu_host_page_size; 673 } 674 } 675 if (real_start != real_end) { 676 mmap(g2h_untagged(real_start), real_end - real_start, PROT_NONE, 677 MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0); 678 } 679 } 680 681 int target_munmap(abi_ulong start, abi_ulong len) 682 { 683 abi_ulong end, real_start, real_end, addr; 684 int prot, ret; 685 686 #ifdef DEBUG_MMAP 687 printf("munmap: start=0x" TARGET_ABI_FMT_lx " len=0x" 688 TARGET_ABI_FMT_lx "\n", 689 start, len); 690 #endif 691 if (start & ~TARGET_PAGE_MASK) 692 return -EINVAL; 693 len = TARGET_PAGE_ALIGN(len); 694 if (len == 0) 695 return -EINVAL; 696 mmap_lock(); 697 end = start + len; 698 real_start = start & qemu_host_page_mask; 699 real_end = HOST_PAGE_ALIGN(end); 700 701 if (start > real_start) { 702 /* handle host page containing start */ 703 prot = 0; 704 for (addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { 705 prot |= page_get_flags(addr); 706 } 707 if (real_end == real_start + qemu_host_page_size) { 708 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 709 prot |= page_get_flags(addr); 710 } 711 end = real_end; 712 } 713 if (prot != 0) 714 real_start += qemu_host_page_size; 715 } 716 if (end < real_end) { 717 prot = 0; 718 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 719 prot |= page_get_flags(addr); 720 } 721 if (prot != 0) 722 real_end -= qemu_host_page_size; 723 } 724 725 ret = 0; 726 /* unmap what we can */ 727 if (real_start < real_end) { 728 if (reserved_va) { 729 mmap_reserve(real_start, real_end - real_start); 730 } else { 731 ret = munmap(g2h_untagged(real_start), real_end - real_start); 732 } 733 } 734 735 if (ret == 0) { 736 page_set_flags(start, start + len - 1, 0); 737 } 738 mmap_unlock(); 739 return ret; 740 } 741 742 int target_msync(abi_ulong start, abi_ulong len, int flags) 743 { 744 abi_ulong end; 745 746 if (start & ~TARGET_PAGE_MASK) 747 return -EINVAL; 748 len = TARGET_PAGE_ALIGN(len); 749 end = start + len; 750 if (end < start) 751 return -EINVAL; 752 if (end == start) 753 return 0; 754 755 start &= qemu_host_page_mask; 756 return msync(g2h_untagged(start), end - start, flags); 757 } 758