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 unsigned long last_brk; 218 219 /* 220 * Subroutine of mmap_find_vma, used when we have pre-allocated a chunk of guest 221 * address space. 222 */ 223 static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, 224 abi_ulong alignment) 225 { 226 abi_ulong ret; 227 228 ret = page_find_range_empty(start, reserved_va, size, alignment); 229 if (ret == -1 && start > TARGET_PAGE_SIZE) { 230 /* Restart at the beginning of the address space. */ 231 ret = page_find_range_empty(TARGET_PAGE_SIZE, start - 1, 232 size, alignment); 233 } 234 235 return ret; 236 } 237 238 /* 239 * Find and reserve a free memory area of size 'size'. The search 240 * starts at 'start'. 241 * It must be called with mmap_lock() held. 242 * Return -1 if error. 243 */ 244 static abi_ulong mmap_find_vma_aligned(abi_ulong start, abi_ulong size, 245 abi_ulong alignment) 246 { 247 void *ptr, *prev; 248 abi_ulong addr; 249 int flags; 250 int wrapped, repeat; 251 252 /* If 'start' == 0, then a default start address is used. */ 253 if (start == 0) { 254 start = mmap_next_start; 255 } else { 256 start &= qemu_host_page_mask; 257 } 258 259 size = HOST_PAGE_ALIGN(size); 260 261 if (reserved_va) { 262 return mmap_find_vma_reserved(start, size, 263 (alignment != 0 ? 1 << alignment : 0)); 264 } 265 266 addr = start; 267 wrapped = repeat = 0; 268 prev = 0; 269 flags = MAP_ANON | MAP_PRIVATE; 270 if (alignment != 0) { 271 flags |= MAP_ALIGNED(alignment); 272 } 273 274 for (;; prev = ptr) { 275 /* 276 * Reserve needed memory area to avoid a race. 277 * It should be discarded using: 278 * - mmap() with MAP_FIXED flag 279 * - mremap() with MREMAP_FIXED flag 280 * - shmat() with SHM_REMAP flag 281 */ 282 ptr = mmap(g2h_untagged(addr), size, PROT_NONE, 283 flags, -1, 0); 284 285 /* ENOMEM, if host address space has no memory */ 286 if (ptr == MAP_FAILED) { 287 return (abi_ulong)-1; 288 } 289 290 /* 291 * Count the number of sequential returns of the same address. 292 * This is used to modify the search algorithm below. 293 */ 294 repeat = (ptr == prev ? repeat + 1 : 0); 295 296 if (h2g_valid(ptr + size - 1)) { 297 addr = h2g(ptr); 298 299 if ((addr & ~TARGET_PAGE_MASK) == 0) { 300 /* Success. */ 301 if (start == mmap_next_start && addr >= TASK_UNMAPPED_BASE) { 302 mmap_next_start = addr + size; 303 } 304 return addr; 305 } 306 307 /* The address is not properly aligned for the target. */ 308 switch (repeat) { 309 case 0: 310 /* 311 * Assume the result that the kernel gave us is the 312 * first with enough free space, so start again at the 313 * next higher target page. 314 */ 315 addr = TARGET_PAGE_ALIGN(addr); 316 break; 317 case 1: 318 /* 319 * Sometimes the kernel decides to perform the allocation 320 * at the top end of memory instead. 321 */ 322 addr &= TARGET_PAGE_MASK; 323 break; 324 case 2: 325 /* Start over at low memory. */ 326 addr = 0; 327 break; 328 default: 329 /* Fail. This unaligned block must the last. */ 330 addr = -1; 331 break; 332 } 333 } else { 334 /* 335 * Since the result the kernel gave didn't fit, start 336 * again at low memory. If any repetition, fail. 337 */ 338 addr = (repeat ? -1 : 0); 339 } 340 341 /* Unmap and try again. */ 342 munmap(ptr, size); 343 344 /* ENOMEM if we checked the whole of the target address space. */ 345 if (addr == (abi_ulong)-1) { 346 return (abi_ulong)-1; 347 } else if (addr == 0) { 348 if (wrapped) { 349 return (abi_ulong)-1; 350 } 351 wrapped = 1; 352 /* 353 * Don't actually use 0 when wrapping, instead indicate 354 * that we'd truly like an allocation in low memory. 355 */ 356 addr = TARGET_PAGE_SIZE; 357 } else if (wrapped && addr >= start) { 358 return (abi_ulong)-1; 359 } 360 } 361 } 362 363 abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) 364 { 365 return mmap_find_vma_aligned(start, size, 0); 366 } 367 368 /* NOTE: all the constants are the HOST ones */ 369 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, 370 int flags, int fd, off_t offset) 371 { 372 abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; 373 374 mmap_lock(); 375 if (qemu_loglevel_mask(CPU_LOG_PAGE)) { 376 qemu_log("mmap: start=0x" TARGET_ABI_FMT_lx 377 " len=0x" TARGET_ABI_FMT_lx " prot=%c%c%c flags=", 378 start, len, 379 prot & PROT_READ ? 'r' : '-', 380 prot & PROT_WRITE ? 'w' : '-', 381 prot & PROT_EXEC ? 'x' : '-'); 382 if (flags & MAP_ALIGNMENT_MASK) { 383 qemu_log("MAP_ALIGNED(%u) ", 384 (flags & MAP_ALIGNMENT_MASK) >> MAP_ALIGNMENT_SHIFT); 385 } 386 if (flags & MAP_GUARD) { 387 qemu_log("MAP_GUARD "); 388 } 389 if (flags & MAP_FIXED) { 390 qemu_log("MAP_FIXED "); 391 } 392 if (flags & MAP_ANON) { 393 qemu_log("MAP_ANON "); 394 } 395 if (flags & MAP_EXCL) { 396 qemu_log("MAP_EXCL "); 397 } 398 if (flags & MAP_PRIVATE) { 399 qemu_log("MAP_PRIVATE "); 400 } 401 if (flags & MAP_SHARED) { 402 qemu_log("MAP_SHARED "); 403 } 404 if (flags & MAP_NOCORE) { 405 qemu_log("MAP_NOCORE "); 406 } 407 if (flags & MAP_STACK) { 408 qemu_log("MAP_STACK "); 409 } 410 qemu_log("fd=%d offset=0x%lx\n", fd, offset); 411 } 412 413 if ((flags & MAP_ANON) && fd != -1) { 414 errno = EINVAL; 415 goto fail; 416 } 417 if (flags & MAP_STACK) { 418 if ((fd != -1) || ((prot & (PROT_READ | PROT_WRITE)) != 419 (PROT_READ | PROT_WRITE))) { 420 errno = EINVAL; 421 goto fail; 422 } 423 } 424 if ((flags & MAP_GUARD) && (prot != PROT_NONE || fd != -1 || 425 offset != 0 || (flags & (MAP_SHARED | MAP_PRIVATE | 426 /* MAP_PREFAULT | */ /* MAP_PREFAULT not in mman.h */ 427 MAP_PREFAULT_READ | MAP_ANON | MAP_STACK)) != 0)) { 428 errno = EINVAL; 429 goto fail; 430 } 431 432 if (offset & ~TARGET_PAGE_MASK) { 433 errno = EINVAL; 434 goto fail; 435 } 436 437 if (len == 0) { 438 errno = EINVAL; 439 goto fail; 440 } 441 442 /* Check for overflows */ 443 len = TARGET_PAGE_ALIGN(len); 444 if (len == 0) { 445 errno = ENOMEM; 446 goto fail; 447 } 448 449 real_start = start & qemu_host_page_mask; 450 host_offset = offset & qemu_host_page_mask; 451 452 /* 453 * If the user is asking for the kernel to find a location, do that 454 * before we truncate the length for mapping files below. 455 */ 456 if (!(flags & MAP_FIXED)) { 457 host_len = len + offset - host_offset; 458 host_len = HOST_PAGE_ALIGN(host_len); 459 if ((flags & MAP_ALIGNMENT_MASK) != 0) 460 start = mmap_find_vma_aligned(real_start, host_len, 461 (flags & MAP_ALIGNMENT_MASK) >> MAP_ALIGNMENT_SHIFT); 462 else 463 start = mmap_find_vma(real_start, host_len); 464 if (start == (abi_ulong)-1) { 465 errno = ENOMEM; 466 goto fail; 467 } 468 } 469 470 /* 471 * When mapping files into a memory area larger than the file, accesses 472 * to pages beyond the file size will cause a SIGBUS. 473 * 474 * For example, if mmaping a file of 100 bytes on a host with 4K pages 475 * emulating a target with 8K pages, the target expects to be able to 476 * access the first 8K. But the host will trap us on any access beyond 477 * 4K. 478 * 479 * When emulating a target with a larger page-size than the hosts, we 480 * may need to truncate file maps at EOF and add extra anonymous pages 481 * up to the targets page boundary. 482 */ 483 484 if ((qemu_real_host_page_size() < qemu_host_page_size) && fd != -1) { 485 struct stat sb; 486 487 if (fstat(fd, &sb) == -1) { 488 goto fail; 489 } 490 491 /* Are we trying to create a map beyond EOF?. */ 492 if (offset + len > sb.st_size) { 493 /* 494 * If so, truncate the file map at eof aligned with 495 * the hosts real pagesize. Additional anonymous maps 496 * will be created beyond EOF. 497 */ 498 len = REAL_HOST_PAGE_ALIGN(sb.st_size - offset); 499 } 500 } 501 502 if (!(flags & MAP_FIXED)) { 503 unsigned long host_start; 504 void *p; 505 506 host_len = len + offset - host_offset; 507 host_len = HOST_PAGE_ALIGN(host_len); 508 509 /* 510 * Note: we prefer to control the mapping address. It is 511 * especially important if qemu_host_page_size > 512 * qemu_real_host_page_size 513 */ 514 p = mmap(g2h_untagged(start), host_len, prot, 515 flags | MAP_FIXED | ((fd != -1) ? MAP_ANON : 0), -1, 0); 516 if (p == MAP_FAILED) 517 goto fail; 518 /* update start so that it points to the file position at 'offset' */ 519 host_start = (unsigned long)p; 520 if (fd != -1) { 521 p = mmap(g2h_untagged(start), len, prot, 522 flags | MAP_FIXED, fd, host_offset); 523 if (p == MAP_FAILED) { 524 munmap(g2h_untagged(start), host_len); 525 goto fail; 526 } 527 host_start += offset - host_offset; 528 } 529 start = h2g(host_start); 530 } else { 531 if (start & ~TARGET_PAGE_MASK) { 532 errno = EINVAL; 533 goto fail; 534 } 535 end = start + len; 536 real_end = HOST_PAGE_ALIGN(end); 537 538 /* 539 * Test if requested memory area fits target address space 540 * It can fail only on 64-bit host with 32-bit target. 541 * On any other target/host host mmap() handles this error correctly. 542 */ 543 if (!guest_range_valid_untagged(start, len)) { 544 errno = EINVAL; 545 goto fail; 546 } 547 548 /* 549 * worst case: we cannot map the file because the offset is not 550 * aligned, so we read it 551 */ 552 if (fd != -1 && 553 (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) { 554 /* 555 * msync() won't work here, so we return an error if write is 556 * possible while it is a shared mapping 557 */ 558 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && 559 (prot & PROT_WRITE)) { 560 errno = EINVAL; 561 goto fail; 562 } 563 retaddr = target_mmap(start, len, prot | PROT_WRITE, 564 MAP_FIXED | MAP_PRIVATE | MAP_ANON, 565 -1, 0); 566 if (retaddr == -1) 567 goto fail; 568 if (pread(fd, g2h_untagged(start), len, offset) == -1) { 569 goto fail; 570 } 571 if (!(prot & PROT_WRITE)) { 572 ret = target_mprotect(start, len, prot); 573 assert(ret == 0); 574 } 575 goto the_end; 576 } 577 578 /* Reject the mapping if any page within the range is mapped */ 579 if ((flags & MAP_EXCL) && !page_check_range_empty(start, end - 1)) { 580 errno = EINVAL; 581 goto fail; 582 } 583 584 /* handle the start of the mapping */ 585 if (start > real_start) { 586 if (real_end == real_start + qemu_host_page_size) { 587 /* one single host page */ 588 ret = mmap_frag(real_start, start, end, 589 prot, flags, fd, offset); 590 if (ret == -1) 591 goto fail; 592 goto the_end1; 593 } 594 ret = mmap_frag(real_start, start, real_start + qemu_host_page_size, 595 prot, flags, fd, offset); 596 if (ret == -1) 597 goto fail; 598 real_start += qemu_host_page_size; 599 } 600 /* handle the end of the mapping */ 601 if (end < real_end) { 602 ret = mmap_frag(real_end - qemu_host_page_size, 603 real_end - qemu_host_page_size, end, 604 prot, flags, fd, 605 offset + real_end - qemu_host_page_size - start); 606 if (ret == -1) 607 goto fail; 608 real_end -= qemu_host_page_size; 609 } 610 611 /* map the middle (easier) */ 612 if (real_start < real_end) { 613 void *p; 614 unsigned long offset1; 615 if (flags & MAP_ANON) 616 offset1 = 0; 617 else 618 offset1 = offset + real_start - start; 619 p = mmap(g2h_untagged(real_start), real_end - real_start, 620 prot, flags, fd, offset1); 621 if (p == MAP_FAILED) 622 goto fail; 623 } 624 } 625 the_end1: 626 page_set_flags(start, start + len - 1, prot | PAGE_VALID); 627 the_end: 628 #ifdef DEBUG_MMAP 629 printf("ret=0x" TARGET_ABI_FMT_lx "\n", start); 630 page_dump(stdout); 631 printf("\n"); 632 #endif 633 mmap_unlock(); 634 return start; 635 fail: 636 mmap_unlock(); 637 return -1; 638 } 639 640 static void mmap_reserve(abi_ulong start, abi_ulong size) 641 { 642 abi_ulong real_start; 643 abi_ulong real_end; 644 abi_ulong addr; 645 abi_ulong end; 646 int prot; 647 648 real_start = start & qemu_host_page_mask; 649 real_end = HOST_PAGE_ALIGN(start + size); 650 end = start + size; 651 if (start > real_start) { 652 /* handle host page containing start */ 653 prot = 0; 654 for (addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { 655 prot |= page_get_flags(addr); 656 } 657 if (real_end == real_start + qemu_host_page_size) { 658 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 659 prot |= page_get_flags(addr); 660 } 661 end = real_end; 662 } 663 if (prot != 0) { 664 real_start += qemu_host_page_size; 665 } 666 } 667 if (end < real_end) { 668 prot = 0; 669 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 670 prot |= page_get_flags(addr); 671 } 672 if (prot != 0) { 673 real_end -= qemu_host_page_size; 674 } 675 } 676 if (real_start != real_end) { 677 mmap(g2h_untagged(real_start), real_end - real_start, PROT_NONE, 678 MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0); 679 } 680 } 681 682 int target_munmap(abi_ulong start, abi_ulong len) 683 { 684 abi_ulong end, real_start, real_end, addr; 685 int prot, ret; 686 687 #ifdef DEBUG_MMAP 688 printf("munmap: start=0x" TARGET_ABI_FMT_lx " len=0x" 689 TARGET_ABI_FMT_lx "\n", 690 start, len); 691 #endif 692 if (start & ~TARGET_PAGE_MASK) 693 return -EINVAL; 694 len = TARGET_PAGE_ALIGN(len); 695 if (len == 0) 696 return -EINVAL; 697 mmap_lock(); 698 end = start + len; 699 real_start = start & qemu_host_page_mask; 700 real_end = HOST_PAGE_ALIGN(end); 701 702 if (start > real_start) { 703 /* handle host page containing start */ 704 prot = 0; 705 for (addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { 706 prot |= page_get_flags(addr); 707 } 708 if (real_end == real_start + qemu_host_page_size) { 709 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 710 prot |= page_get_flags(addr); 711 } 712 end = real_end; 713 } 714 if (prot != 0) 715 real_start += qemu_host_page_size; 716 } 717 if (end < real_end) { 718 prot = 0; 719 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 720 prot |= page_get_flags(addr); 721 } 722 if (prot != 0) 723 real_end -= qemu_host_page_size; 724 } 725 726 ret = 0; 727 /* unmap what we can */ 728 if (real_start < real_end) { 729 if (reserved_va) { 730 mmap_reserve(real_start, real_end - real_start); 731 } else { 732 ret = munmap(g2h_untagged(real_start), real_end - real_start); 733 } 734 } 735 736 if (ret == 0) { 737 page_set_flags(start, start + len - 1, 0); 738 } 739 mmap_unlock(); 740 return ret; 741 } 742 743 int target_msync(abi_ulong start, abi_ulong len, int flags) 744 { 745 abi_ulong end; 746 747 if (start & ~TARGET_PAGE_MASK) 748 return -EINVAL; 749 len = TARGET_PAGE_ALIGN(len); 750 end = start + len; 751 if (end < start) 752 return -EINVAL; 753 if (end == start) 754 return 0; 755 756 start &= qemu_host_page_mask; 757 return msync(g2h_untagged(start), end - start, flags); 758 } 759