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 <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" 29 #include "bsd-mman.h" 30 31 //#define DEBUG_MMAP 32 33 #if defined(CONFIG_USE_NPTL) 34 pthread_mutex_t mmap_mutex; 35 static int __thread mmap_lock_count; 36 37 void mmap_lock(void) 38 { 39 if (mmap_lock_count++ == 0) { 40 pthread_mutex_lock(&mmap_mutex); 41 } 42 } 43 44 void 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(). */ 52 void mmap_fork_start(void) 53 { 54 if (mmap_lock_count) 55 abort(); 56 pthread_mutex_lock(&mmap_mutex); 57 } 58 59 void 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. */ 68 void mmap_lock(void) 69 { 70 } 71 72 void mmap_unlock(void) 73 { 74 } 75 #endif 76 77 void *qemu_vmalloc(size_t size) 78 { 79 void *p; 80 unsigned long addr; 81 mmap_lock(); 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); 85 86 addr = (unsigned long)p; 87 if (addr == (target_ulong) addr) { 88 /* Allocated region overlaps guest address space. 89 This may recurse. */ 90 page_set_flags(addr & TARGET_PAGE_MASK, TARGET_PAGE_ALIGN(addr + size), 91 PAGE_RESERVED); 92 } 93 94 mmap_unlock(); 95 return p; 96 } 97 98 void *qemu_malloc(size_t size) 99 { 100 char * p; 101 size += 16; 102 p = qemu_vmalloc(size); 103 *(size_t *)p = size; 104 return p + 16; 105 } 106 107 /* We use map, which is always zero initialized. */ 108 void * qemu_mallocz(size_t size) 109 { 110 return qemu_malloc(size); 111 } 112 113 void qemu_free(void *ptr) 114 { 115 /* FIXME: We should unmark the reserved pages here. However this gets 116 complicated when one target page spans multiple host pages, so we 117 don't bother. */ 118 size_t *p; 119 p = (size_t *)((char *)ptr - 16); 120 munmap(p, *p); 121 } 122 123 void *qemu_realloc(void *ptr, size_t size) 124 { 125 size_t old_size, copy; 126 void *new_ptr; 127 128 if (!ptr) 129 return qemu_malloc(size); 130 old_size = *(size_t *)((char *)ptr - 16); 131 copy = old_size < size ? old_size : size; 132 new_ptr = qemu_malloc(size); 133 memcpy(new_ptr, ptr, copy); 134 qemu_free(ptr); 135 return new_ptr; 136 } 137 138 /* NOTE: all the constants are the HOST ones, but addresses are target. */ 139 int target_mprotect(abi_ulong start, abi_ulong len, int prot) 140 { 141 abi_ulong end, host_start, host_end, addr; 142 int prot1, ret; 143 144 #ifdef DEBUG_MMAP 145 printf("mprotect: start=0x" TARGET_FMT_lx 146 " len=0x" TARGET_FMT_lx " prot=%c%c%c\n", start, len, 147 prot & PROT_READ ? 'r' : '-', 148 prot & PROT_WRITE ? 'w' : '-', 149 prot & PROT_EXEC ? 'x' : '-'); 150 #endif 151 152 if ((start & ~TARGET_PAGE_MASK) != 0) 153 return -EINVAL; 154 len = TARGET_PAGE_ALIGN(len); 155 end = start + len; 156 if (end < start) 157 return -EINVAL; 158 prot &= PROT_READ | PROT_WRITE | PROT_EXEC; 159 if (len == 0) 160 return 0; 161 162 mmap_lock(); 163 host_start = start & qemu_host_page_mask; 164 host_end = HOST_PAGE_ALIGN(end); 165 if (start > host_start) { 166 /* handle host page containing start */ 167 prot1 = prot; 168 for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) { 169 prot1 |= page_get_flags(addr); 170 } 171 if (host_end == host_start + qemu_host_page_size) { 172 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 173 prot1 |= page_get_flags(addr); 174 } 175 end = host_end; 176 } 177 ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS); 178 if (ret != 0) 179 goto error; 180 host_start += qemu_host_page_size; 181 } 182 if (end < host_end) { 183 prot1 = prot; 184 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 185 prot1 |= page_get_flags(addr); 186 } 187 ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size, 188 prot1 & PAGE_BITS); 189 if (ret != 0) 190 goto error; 191 host_end -= qemu_host_page_size; 192 } 193 194 /* handle the pages in the middle */ 195 if (host_start < host_end) { 196 ret = mprotect(g2h(host_start), host_end - host_start, prot); 197 if (ret != 0) 198 goto error; 199 } 200 page_set_flags(start, start + len, prot | PAGE_VALID); 201 mmap_unlock(); 202 return 0; 203 error: 204 mmap_unlock(); 205 return ret; 206 } 207 208 /* map an incomplete host page */ 209 static int mmap_frag(abi_ulong real_start, 210 abi_ulong start, abi_ulong end, 211 int prot, int flags, int fd, abi_ulong offset) 212 { 213 abi_ulong real_end, addr; 214 void *host_start; 215 int prot1, prot_new; 216 217 real_end = real_start + qemu_host_page_size; 218 host_start = g2h(real_start); 219 220 /* get the protection of the target pages outside the mapping */ 221 prot1 = 0; 222 for(addr = real_start; addr < real_end; addr++) { 223 if (addr < start || addr >= end) 224 prot1 |= page_get_flags(addr); 225 } 226 227 if (prot1 == 0) { 228 /* no page was there, so we allocate one */ 229 void *p = mmap(host_start, qemu_host_page_size, prot, 230 flags | MAP_ANON, -1, 0); 231 if (p == MAP_FAILED) 232 return -1; 233 prot1 = prot; 234 } 235 prot1 &= PAGE_BITS; 236 237 prot_new = prot | prot1; 238 if (!(flags & MAP_ANON)) { 239 /* msync() won't work here, so we return an error if write is 240 possible while it is a shared mapping */ 241 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && 242 (prot & PROT_WRITE)) 243 return -EINVAL; 244 245 /* adjust protection to be able to read */ 246 if (!(prot1 & PROT_WRITE)) 247 mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE); 248 249 /* read the corresponding file data */ 250 pread(fd, g2h(start), end - start, offset); 251 252 /* put final protection */ 253 if (prot_new != (prot1 | PROT_WRITE)) 254 mprotect(host_start, qemu_host_page_size, prot_new); 255 } else { 256 /* just update the protection */ 257 if (prot_new != prot1) { 258 mprotect(host_start, qemu_host_page_size, prot_new); 259 } 260 } 261 return 0; 262 } 263 264 #if defined(__CYGWIN__) 265 /* Cygwin doesn't have a whole lot of address space. */ 266 static abi_ulong mmap_next_start = 0x18000000; 267 #else 268 static abi_ulong mmap_next_start = 0x40000000; 269 #endif 270 271 unsigned long last_brk; 272 273 /* find a free memory area of size 'size'. The search starts at 274 'start'. If 'start' == 0, then a default start address is used. 275 Return -1 if error. 276 */ 277 /* page_init() marks pages used by the host as reserved to be sure not 278 to use them. */ 279 static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) 280 { 281 abi_ulong addr, addr1, addr_start; 282 int prot; 283 unsigned long new_brk; 284 285 new_brk = (unsigned long)sbrk(0); 286 if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) { 287 /* This is a hack to catch the host allocating memory with brk(). 288 If it uses mmap then we loose. 289 FIXME: We really want to avoid the host allocating memory in 290 the first place, and maybe leave some slack to avoid switching 291 to mmap. */ 292 page_set_flags(last_brk & TARGET_PAGE_MASK, 293 TARGET_PAGE_ALIGN(new_brk), 294 PAGE_RESERVED); 295 } 296 last_brk = new_brk; 297 298 size = HOST_PAGE_ALIGN(size); 299 start = start & qemu_host_page_mask; 300 addr = start; 301 if (addr == 0) 302 addr = mmap_next_start; 303 addr_start = addr; 304 for(;;) { 305 prot = 0; 306 for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) { 307 prot |= page_get_flags(addr1); 308 } 309 if (prot == 0) 310 break; 311 addr += qemu_host_page_size; 312 /* we found nothing */ 313 if (addr == addr_start) 314 return (abi_ulong)-1; 315 } 316 if (start == 0) 317 mmap_next_start = addr + size; 318 return addr; 319 } 320 321 /* NOTE: all the constants are the HOST ones */ 322 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, 323 int flags, int fd, abi_ulong offset) 324 { 325 abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; 326 unsigned long host_start; 327 328 mmap_lock(); 329 #ifdef DEBUG_MMAP 330 { 331 printf("mmap: start=0x" TARGET_FMT_lx 332 " len=0x" TARGET_FMT_lx " prot=%c%c%c flags=", 333 start, len, 334 prot & PROT_READ ? 'r' : '-', 335 prot & PROT_WRITE ? 'w' : '-', 336 prot & PROT_EXEC ? 'x' : '-'); 337 if (flags & MAP_FIXED) 338 printf("MAP_FIXED "); 339 if (flags & MAP_ANON) 340 printf("MAP_ANON "); 341 switch(flags & TARGET_BSD_MAP_FLAGMASK) { 342 case MAP_PRIVATE: 343 printf("MAP_PRIVATE "); 344 break; 345 case MAP_SHARED: 346 printf("MAP_SHARED "); 347 break; 348 default: 349 printf("[MAP_FLAGMASK=0x%x] ", flags & TARGET_BSD_MAP_FLAGMASK); 350 break; 351 } 352 printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset); 353 } 354 #endif 355 356 if (offset & ~TARGET_PAGE_MASK) { 357 errno = EINVAL; 358 goto fail; 359 } 360 361 len = TARGET_PAGE_ALIGN(len); 362 if (len == 0) 363 goto the_end; 364 real_start = start & qemu_host_page_mask; 365 366 if (!(flags & MAP_FIXED)) { 367 abi_ulong mmap_start; 368 void *p; 369 host_offset = offset & qemu_host_page_mask; 370 host_len = len + offset - host_offset; 371 host_len = HOST_PAGE_ALIGN(host_len); 372 mmap_start = mmap_find_vma(real_start, host_len); 373 if (mmap_start == (abi_ulong)-1) { 374 errno = ENOMEM; 375 goto fail; 376 } 377 /* Note: we prefer to control the mapping address. It is 378 especially important if qemu_host_page_size > 379 qemu_real_host_page_size */ 380 p = mmap(g2h(mmap_start), 381 host_len, prot, flags | MAP_FIXED, fd, host_offset); 382 if (p == MAP_FAILED) 383 goto fail; 384 /* update start so that it points to the file position at 'offset' */ 385 host_start = (unsigned long)p; 386 if (!(flags & MAP_ANON)) 387 host_start += offset - host_offset; 388 start = h2g(host_start); 389 } else { 390 int flg; 391 target_ulong addr; 392 393 if (start & ~TARGET_PAGE_MASK) { 394 errno = EINVAL; 395 goto fail; 396 } 397 end = start + len; 398 real_end = HOST_PAGE_ALIGN(end); 399 400 for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) { 401 flg = page_get_flags(addr); 402 if (flg & PAGE_RESERVED) { 403 errno = ENXIO; 404 goto fail; 405 } 406 } 407 408 /* worst case: we cannot map the file because the offset is not 409 aligned, so we read it */ 410 if (!(flags & MAP_ANON) && 411 (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) { 412 /* msync() won't work here, so we return an error if write is 413 possible while it is a shared mapping */ 414 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && 415 (prot & PROT_WRITE)) { 416 errno = EINVAL; 417 goto fail; 418 } 419 retaddr = target_mmap(start, len, prot | PROT_WRITE, 420 MAP_FIXED | MAP_PRIVATE | MAP_ANON, 421 -1, 0); 422 if (retaddr == -1) 423 goto fail; 424 pread(fd, g2h(start), len, offset); 425 if (!(prot & PROT_WRITE)) { 426 ret = target_mprotect(start, len, prot); 427 if (ret != 0) { 428 start = ret; 429 goto the_end; 430 } 431 } 432 goto the_end; 433 } 434 435 /* handle the start of the mapping */ 436 if (start > real_start) { 437 if (real_end == real_start + qemu_host_page_size) { 438 /* one single host page */ 439 ret = mmap_frag(real_start, start, end, 440 prot, flags, fd, offset); 441 if (ret == -1) 442 goto fail; 443 goto the_end1; 444 } 445 ret = mmap_frag(real_start, start, real_start + qemu_host_page_size, 446 prot, flags, fd, offset); 447 if (ret == -1) 448 goto fail; 449 real_start += qemu_host_page_size; 450 } 451 /* handle the end of the mapping */ 452 if (end < real_end) { 453 ret = mmap_frag(real_end - qemu_host_page_size, 454 real_end - qemu_host_page_size, real_end, 455 prot, flags, fd, 456 offset + real_end - qemu_host_page_size - start); 457 if (ret == -1) 458 goto fail; 459 real_end -= qemu_host_page_size; 460 } 461 462 /* map the middle (easier) */ 463 if (real_start < real_end) { 464 void *p; 465 unsigned long offset1; 466 if (flags & MAP_ANON) 467 offset1 = 0; 468 else 469 offset1 = offset + real_start - start; 470 p = mmap(g2h(real_start), real_end - real_start, 471 prot, flags, fd, offset1); 472 if (p == MAP_FAILED) 473 goto fail; 474 } 475 } 476 the_end1: 477 page_set_flags(start, start + len, prot | PAGE_VALID); 478 the_end: 479 #ifdef DEBUG_MMAP 480 printf("ret=0x" TARGET_FMT_lx "\n", start); 481 page_dump(stdout); 482 printf("\n"); 483 #endif 484 mmap_unlock(); 485 return start; 486 fail: 487 mmap_unlock(); 488 return -1; 489 } 490 491 int target_munmap(abi_ulong start, abi_ulong len) 492 { 493 abi_ulong end, real_start, real_end, addr; 494 int prot, ret; 495 496 #ifdef DEBUG_MMAP 497 printf("munmap: start=0x%lx len=0x%lx\n", start, len); 498 #endif 499 if (start & ~TARGET_PAGE_MASK) 500 return -EINVAL; 501 len = TARGET_PAGE_ALIGN(len); 502 if (len == 0) 503 return -EINVAL; 504 mmap_lock(); 505 end = start + len; 506 real_start = start & qemu_host_page_mask; 507 real_end = HOST_PAGE_ALIGN(end); 508 509 if (start > real_start) { 510 /* handle host page containing start */ 511 prot = 0; 512 for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { 513 prot |= page_get_flags(addr); 514 } 515 if (real_end == real_start + qemu_host_page_size) { 516 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 517 prot |= page_get_flags(addr); 518 } 519 end = real_end; 520 } 521 if (prot != 0) 522 real_start += qemu_host_page_size; 523 } 524 if (end < real_end) { 525 prot = 0; 526 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 527 prot |= page_get_flags(addr); 528 } 529 if (prot != 0) 530 real_end -= qemu_host_page_size; 531 } 532 533 ret = 0; 534 /* unmap what we can */ 535 if (real_start < real_end) { 536 ret = munmap(g2h(real_start), real_end - real_start); 537 } 538 539 if (ret == 0) 540 page_set_flags(start, start + len, 0); 541 mmap_unlock(); 542 return ret; 543 } 544 545 int target_msync(abi_ulong start, abi_ulong len, int flags) 546 { 547 abi_ulong end; 548 549 if (start & ~TARGET_PAGE_MASK) 550 return -EINVAL; 551 len = TARGET_PAGE_ALIGN(len); 552 end = start + len; 553 if (end < start) 554 return -EINVAL; 555 if (end == start) 556 return 0; 557 558 start &= qemu_host_page_mask; 559 return msync(g2h(start), end - start, flags); 560 } 561