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 static void *bsd_vmalloc(size_t size) 78 { 79 void *p; 80 mmap_lock(); 81 /* Use map and mark the pages as used. */ 82 p = mmap(NULL, size, PROT_READ | PROT_WRITE, 83 MAP_PRIVATE | MAP_ANON, -1, 0); 84 85 if (h2g_valid(p)) { 86 /* Allocated region overlaps guest address space. 87 This may recurse. */ 88 abi_ulong addr = h2g(p); 89 page_set_flags(addr & TARGET_PAGE_MASK, TARGET_PAGE_ALIGN(addr + size), 90 PAGE_RESERVED); 91 } 92 93 mmap_unlock(); 94 return p; 95 } 96 97 void *g_malloc(size_t size) 98 { 99 char * p; 100 size += 16; 101 p = bsd_vmalloc(size); 102 *(size_t *)p = size; 103 return p + 16; 104 } 105 106 /* We use map, which is always zero initialized. */ 107 void * g_malloc0(size_t size) 108 { 109 return g_malloc(size); 110 } 111 112 void g_free(void *ptr) 113 { 114 /* FIXME: We should unmark the reserved pages here. However this gets 115 complicated when one target page spans multiple host pages, so we 116 don't bother. */ 117 size_t *p; 118 p = (size_t *)((char *)ptr - 16); 119 munmap(p, *p); 120 } 121 122 void *g_realloc(void *ptr, size_t size) 123 { 124 size_t old_size, copy; 125 void *new_ptr; 126 127 if (!ptr) 128 return g_malloc(size); 129 old_size = *(size_t *)((char *)ptr - 16); 130 copy = old_size < size ? old_size : size; 131 new_ptr = g_malloc(size); 132 memcpy(new_ptr, ptr, copy); 133 g_free(ptr); 134 return new_ptr; 135 } 136 137 /* NOTE: all the constants are the HOST ones, but addresses are target. */ 138 int target_mprotect(abi_ulong start, abi_ulong len, int prot) 139 { 140 abi_ulong end, host_start, host_end, addr; 141 int prot1, ret; 142 143 #ifdef DEBUG_MMAP 144 printf("mprotect: start=0x" TARGET_FMT_lx 145 " len=0x" TARGET_FMT_lx " prot=%c%c%c\n", start, len, 146 prot & PROT_READ ? 'r' : '-', 147 prot & PROT_WRITE ? 'w' : '-', 148 prot & PROT_EXEC ? 'x' : '-'); 149 #endif 150 151 if ((start & ~TARGET_PAGE_MASK) != 0) 152 return -EINVAL; 153 len = TARGET_PAGE_ALIGN(len); 154 end = start + len; 155 if (end < start) 156 return -EINVAL; 157 prot &= PROT_READ | PROT_WRITE | PROT_EXEC; 158 if (len == 0) 159 return 0; 160 161 mmap_lock(); 162 host_start = start & qemu_host_page_mask; 163 host_end = HOST_PAGE_ALIGN(end); 164 if (start > host_start) { 165 /* handle host page containing start */ 166 prot1 = prot; 167 for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) { 168 prot1 |= page_get_flags(addr); 169 } 170 if (host_end == host_start + qemu_host_page_size) { 171 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 172 prot1 |= page_get_flags(addr); 173 } 174 end = host_end; 175 } 176 ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS); 177 if (ret != 0) 178 goto error; 179 host_start += qemu_host_page_size; 180 } 181 if (end < host_end) { 182 prot1 = prot; 183 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 184 prot1 |= page_get_flags(addr); 185 } 186 ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size, 187 prot1 & PAGE_BITS); 188 if (ret != 0) 189 goto error; 190 host_end -= qemu_host_page_size; 191 } 192 193 /* handle the pages in the middle */ 194 if (host_start < host_end) { 195 ret = mprotect(g2h(host_start), host_end - host_start, prot); 196 if (ret != 0) 197 goto error; 198 } 199 page_set_flags(start, start + len, prot | PAGE_VALID); 200 mmap_unlock(); 201 return 0; 202 error: 203 mmap_unlock(); 204 return ret; 205 } 206 207 /* map an incomplete host page */ 208 static int mmap_frag(abi_ulong real_start, 209 abi_ulong start, abi_ulong end, 210 int prot, int flags, int fd, abi_ulong offset) 211 { 212 abi_ulong real_end, addr; 213 void *host_start; 214 int prot1, prot_new; 215 216 real_end = real_start + qemu_host_page_size; 217 host_start = g2h(real_start); 218 219 /* get the protection of the target pages outside the mapping */ 220 prot1 = 0; 221 for(addr = real_start; addr < real_end; addr++) { 222 if (addr < start || addr >= end) 223 prot1 |= page_get_flags(addr); 224 } 225 226 if (prot1 == 0) { 227 /* no page was there, so we allocate one */ 228 void *p = mmap(host_start, qemu_host_page_size, prot, 229 flags | MAP_ANON, -1, 0); 230 if (p == MAP_FAILED) 231 return -1; 232 prot1 = prot; 233 } 234 prot1 &= PAGE_BITS; 235 236 prot_new = prot | prot1; 237 if (!(flags & MAP_ANON)) { 238 /* msync() won't work here, so we return an error if write is 239 possible while it is a shared mapping */ 240 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && 241 (prot & PROT_WRITE)) 242 return -1; 243 244 /* adjust protection to be able to read */ 245 if (!(prot1 & PROT_WRITE)) 246 mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE); 247 248 /* read the corresponding file data */ 249 pread(fd, g2h(start), end - start, offset); 250 251 /* put final protection */ 252 if (prot_new != (prot1 | PROT_WRITE)) 253 mprotect(host_start, qemu_host_page_size, prot_new); 254 } else { 255 /* just update the protection */ 256 if (prot_new != prot1) { 257 mprotect(host_start, qemu_host_page_size, prot_new); 258 } 259 } 260 return 0; 261 } 262 263 #if defined(__CYGWIN__) 264 /* Cygwin doesn't have a whole lot of address space. */ 265 static abi_ulong mmap_next_start = 0x18000000; 266 #else 267 static abi_ulong mmap_next_start = 0x40000000; 268 #endif 269 270 unsigned long last_brk; 271 272 /* find a free memory area of size 'size'. The search starts at 273 'start'. If 'start' == 0, then a default start address is used. 274 Return -1 if error. 275 */ 276 /* page_init() marks pages used by the host as reserved to be sure not 277 to use them. */ 278 static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) 279 { 280 abi_ulong addr, addr1, addr_start; 281 int prot; 282 unsigned long new_brk; 283 284 new_brk = (unsigned long)sbrk(0); 285 if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) { 286 /* This is a hack to catch the host allocating memory with brk(). 287 If it uses mmap then we loose. 288 FIXME: We really want to avoid the host allocating memory in 289 the first place, and maybe leave some slack to avoid switching 290 to mmap. */ 291 page_set_flags(last_brk & TARGET_PAGE_MASK, 292 TARGET_PAGE_ALIGN(new_brk), 293 PAGE_RESERVED); 294 } 295 last_brk = new_brk; 296 297 size = HOST_PAGE_ALIGN(size); 298 start = start & qemu_host_page_mask; 299 addr = start; 300 if (addr == 0) 301 addr = mmap_next_start; 302 addr_start = addr; 303 for(;;) { 304 prot = 0; 305 for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) { 306 prot |= page_get_flags(addr1); 307 } 308 if (prot == 0) 309 break; 310 addr += qemu_host_page_size; 311 /* we found nothing */ 312 if (addr == addr_start) 313 return (abi_ulong)-1; 314 } 315 if (start == 0) 316 mmap_next_start = addr + size; 317 return addr; 318 } 319 320 /* NOTE: all the constants are the HOST ones */ 321 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, 322 int flags, int fd, abi_ulong offset) 323 { 324 abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; 325 unsigned long host_start; 326 327 mmap_lock(); 328 #ifdef DEBUG_MMAP 329 { 330 printf("mmap: start=0x" TARGET_FMT_lx 331 " len=0x" TARGET_FMT_lx " prot=%c%c%c flags=", 332 start, len, 333 prot & PROT_READ ? 'r' : '-', 334 prot & PROT_WRITE ? 'w' : '-', 335 prot & PROT_EXEC ? 'x' : '-'); 336 if (flags & MAP_FIXED) 337 printf("MAP_FIXED "); 338 if (flags & MAP_ANON) 339 printf("MAP_ANON "); 340 switch(flags & TARGET_BSD_MAP_FLAGMASK) { 341 case MAP_PRIVATE: 342 printf("MAP_PRIVATE "); 343 break; 344 case MAP_SHARED: 345 printf("MAP_SHARED "); 346 break; 347 default: 348 printf("[MAP_FLAGMASK=0x%x] ", flags & TARGET_BSD_MAP_FLAGMASK); 349 break; 350 } 351 printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset); 352 } 353 #endif 354 355 if (offset & ~TARGET_PAGE_MASK) { 356 errno = EINVAL; 357 goto fail; 358 } 359 360 len = TARGET_PAGE_ALIGN(len); 361 if (len == 0) 362 goto the_end; 363 real_start = start & qemu_host_page_mask; 364 365 if (!(flags & MAP_FIXED)) { 366 abi_ulong mmap_start; 367 void *p; 368 host_offset = offset & qemu_host_page_mask; 369 host_len = len + offset - host_offset; 370 host_len = HOST_PAGE_ALIGN(host_len); 371 mmap_start = mmap_find_vma(real_start, host_len); 372 if (mmap_start == (abi_ulong)-1) { 373 errno = ENOMEM; 374 goto fail; 375 } 376 /* Note: we prefer to control the mapping address. It is 377 especially important if qemu_host_page_size > 378 qemu_real_host_page_size */ 379 p = mmap(g2h(mmap_start), 380 host_len, prot, flags | MAP_FIXED, fd, host_offset); 381 if (p == MAP_FAILED) 382 goto fail; 383 /* update start so that it points to the file position at 'offset' */ 384 host_start = (unsigned long)p; 385 if (!(flags & MAP_ANON)) 386 host_start += offset - host_offset; 387 start = h2g(host_start); 388 } else { 389 int flg; 390 target_ulong addr; 391 392 if (start & ~TARGET_PAGE_MASK) { 393 errno = EINVAL; 394 goto fail; 395 } 396 end = start + len; 397 real_end = HOST_PAGE_ALIGN(end); 398 399 for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) { 400 flg = page_get_flags(addr); 401 if (flg & PAGE_RESERVED) { 402 errno = ENXIO; 403 goto fail; 404 } 405 } 406 407 /* worst case: we cannot map the file because the offset is not 408 aligned, so we read it */ 409 if (!(flags & MAP_ANON) && 410 (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) { 411 /* msync() won't work here, so we return an error if write is 412 possible while it is a shared mapping */ 413 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && 414 (prot & PROT_WRITE)) { 415 errno = EINVAL; 416 goto fail; 417 } 418 retaddr = target_mmap(start, len, prot | PROT_WRITE, 419 MAP_FIXED | MAP_PRIVATE | MAP_ANON, 420 -1, 0); 421 if (retaddr == -1) 422 goto fail; 423 pread(fd, g2h(start), len, offset); 424 if (!(prot & PROT_WRITE)) { 425 ret = target_mprotect(start, len, prot); 426 if (ret != 0) { 427 start = ret; 428 goto the_end; 429 } 430 } 431 goto the_end; 432 } 433 434 /* handle the start of the mapping */ 435 if (start > real_start) { 436 if (real_end == real_start + qemu_host_page_size) { 437 /* one single host page */ 438 ret = mmap_frag(real_start, start, end, 439 prot, flags, fd, offset); 440 if (ret == -1) 441 goto fail; 442 goto the_end1; 443 } 444 ret = mmap_frag(real_start, start, real_start + qemu_host_page_size, 445 prot, flags, fd, offset); 446 if (ret == -1) 447 goto fail; 448 real_start += qemu_host_page_size; 449 } 450 /* handle the end of the mapping */ 451 if (end < real_end) { 452 ret = mmap_frag(real_end - qemu_host_page_size, 453 real_end - qemu_host_page_size, real_end, 454 prot, flags, fd, 455 offset + real_end - qemu_host_page_size - start); 456 if (ret == -1) 457 goto fail; 458 real_end -= qemu_host_page_size; 459 } 460 461 /* map the middle (easier) */ 462 if (real_start < real_end) { 463 void *p; 464 unsigned long offset1; 465 if (flags & MAP_ANON) 466 offset1 = 0; 467 else 468 offset1 = offset + real_start - start; 469 p = mmap(g2h(real_start), real_end - real_start, 470 prot, flags, fd, offset1); 471 if (p == MAP_FAILED) 472 goto fail; 473 } 474 } 475 the_end1: 476 page_set_flags(start, start + len, prot | PAGE_VALID); 477 the_end: 478 #ifdef DEBUG_MMAP 479 printf("ret=0x" TARGET_FMT_lx "\n", start); 480 page_dump(stdout); 481 printf("\n"); 482 #endif 483 mmap_unlock(); 484 return start; 485 fail: 486 mmap_unlock(); 487 return -1; 488 } 489 490 int target_munmap(abi_ulong start, abi_ulong len) 491 { 492 abi_ulong end, real_start, real_end, addr; 493 int prot, ret; 494 495 #ifdef DEBUG_MMAP 496 printf("munmap: start=0x%lx len=0x%lx\n", start, len); 497 #endif 498 if (start & ~TARGET_PAGE_MASK) 499 return -EINVAL; 500 len = TARGET_PAGE_ALIGN(len); 501 if (len == 0) 502 return -EINVAL; 503 mmap_lock(); 504 end = start + len; 505 real_start = start & qemu_host_page_mask; 506 real_end = HOST_PAGE_ALIGN(end); 507 508 if (start > real_start) { 509 /* handle host page containing start */ 510 prot = 0; 511 for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { 512 prot |= page_get_flags(addr); 513 } 514 if (real_end == real_start + qemu_host_page_size) { 515 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 516 prot |= page_get_flags(addr); 517 } 518 end = real_end; 519 } 520 if (prot != 0) 521 real_start += qemu_host_page_size; 522 } 523 if (end < real_end) { 524 prot = 0; 525 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 526 prot |= page_get_flags(addr); 527 } 528 if (prot != 0) 529 real_end -= qemu_host_page_size; 530 } 531 532 ret = 0; 533 /* unmap what we can */ 534 if (real_start < real_end) { 535 ret = munmap(g2h(real_start), real_end - real_start); 536 } 537 538 if (ret == 0) 539 page_set_flags(start, start + len, 0); 540 mmap_unlock(); 541 return ret; 542 } 543 544 int target_msync(abi_ulong start, abi_ulong len, int flags) 545 { 546 abi_ulong end; 547 548 if (start & ~TARGET_PAGE_MASK) 549 return -EINVAL; 550 len = TARGET_PAGE_ALIGN(len); 551 end = start + len; 552 if (end < start) 553 return -EINVAL; 554 if (end == start) 555 return 0; 556 557 start &= qemu_host_page_mask; 558 return msync(g2h(start), end - start, flags); 559 } 560