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, write to the Free Software 18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 19 */ 20 #include <stdlib.h> 21 #include <stdio.h> 22 #include <stdarg.h> 23 #include <string.h> 24 #include <unistd.h> 25 #include <errno.h> 26 #include <sys/mman.h> 27 28 #include "qemu.h" 29 #include "qemu-common.h" 30 31 //#define DEBUG_MMAP 32 33 #if defined(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 /* NOTE: all the constants are the HOST ones, but addresses are target. */ 124 int target_mprotect(abi_ulong start, abi_ulong len, int prot) 125 { 126 abi_ulong end, host_start, host_end, addr; 127 int prot1, ret; 128 129 #ifdef DEBUG_MMAP 130 printf("mprotect: start=0x" TARGET_FMT_lx 131 " len=0x" TARGET_FMT_lx " prot=%c%c%c\n", start, len, 132 prot & PROT_READ ? 'r' : '-', 133 prot & PROT_WRITE ? 'w' : '-', 134 prot & PROT_EXEC ? 'x' : '-'); 135 #endif 136 137 if ((start & ~TARGET_PAGE_MASK) != 0) 138 return -EINVAL; 139 len = TARGET_PAGE_ALIGN(len); 140 end = start + len; 141 if (end < start) 142 return -EINVAL; 143 prot &= PROT_READ | PROT_WRITE | PROT_EXEC; 144 if (len == 0) 145 return 0; 146 147 mmap_lock(); 148 host_start = start & qemu_host_page_mask; 149 host_end = HOST_PAGE_ALIGN(end); 150 if (start > host_start) { 151 /* handle host page containing start */ 152 prot1 = prot; 153 for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) { 154 prot1 |= page_get_flags(addr); 155 } 156 if (host_end == host_start + qemu_host_page_size) { 157 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 158 prot1 |= page_get_flags(addr); 159 } 160 end = host_end; 161 } 162 ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS); 163 if (ret != 0) 164 goto error; 165 host_start += qemu_host_page_size; 166 } 167 if (end < host_end) { 168 prot1 = prot; 169 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 170 prot1 |= page_get_flags(addr); 171 } 172 ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size, 173 prot1 & PAGE_BITS); 174 if (ret != 0) 175 goto error; 176 host_end -= qemu_host_page_size; 177 } 178 179 /* handle the pages in the middle */ 180 if (host_start < host_end) { 181 ret = mprotect(g2h(host_start), host_end - host_start, prot); 182 if (ret != 0) 183 goto error; 184 } 185 page_set_flags(start, start + len, prot | PAGE_VALID); 186 mmap_unlock(); 187 return 0; 188 error: 189 mmap_unlock(); 190 return ret; 191 } 192 193 /* map an incomplete host page */ 194 static int mmap_frag(abi_ulong real_start, 195 abi_ulong start, abi_ulong end, 196 int prot, int flags, int fd, abi_ulong offset) 197 { 198 abi_ulong real_end, addr; 199 void *host_start; 200 int prot1, prot_new; 201 202 real_end = real_start + qemu_host_page_size; 203 host_start = g2h(real_start); 204 205 /* get the protection of the target pages outside the mapping */ 206 prot1 = 0; 207 for(addr = real_start; addr < real_end; addr++) { 208 if (addr < start || addr >= end) 209 prot1 |= page_get_flags(addr); 210 } 211 212 if (prot1 == 0) { 213 /* no page was there, so we allocate one */ 214 void *p = mmap(host_start, qemu_host_page_size, prot, 215 flags | MAP_ANON, -1, 0); 216 if (p == MAP_FAILED) 217 return -1; 218 prot1 = prot; 219 } 220 prot1 &= PAGE_BITS; 221 222 prot_new = prot | prot1; 223 if (!(flags & MAP_ANON)) { 224 /* msync() won't work here, so we return an error if write is 225 possible while it is a shared mapping */ 226 if ((flags & MAP_FLAGMASK) == MAP_SHARED && 227 (prot & PROT_WRITE)) 228 return -EINVAL; 229 230 /* adjust protection to be able to read */ 231 if (!(prot1 & PROT_WRITE)) 232 mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE); 233 234 /* read the corresponding file data */ 235 pread(fd, g2h(start), end - start, offset); 236 237 /* put final protection */ 238 if (prot_new != (prot1 | PROT_WRITE)) 239 mprotect(host_start, qemu_host_page_size, prot_new); 240 } else { 241 /* just update the protection */ 242 if (prot_new != prot1) { 243 mprotect(host_start, qemu_host_page_size, prot_new); 244 } 245 } 246 return 0; 247 } 248 249 #if defined(__CYGWIN__) 250 /* Cygwin doesn't have a whole lot of address space. */ 251 static abi_ulong mmap_next_start = 0x18000000; 252 #else 253 static abi_ulong mmap_next_start = 0x40000000; 254 #endif 255 256 unsigned long last_brk; 257 258 /* find a free memory area of size 'size'. The search starts at 259 'start'. If 'start' == 0, then a default start address is used. 260 Return -1 if error. 261 */ 262 /* page_init() marks pages used by the host as reserved to be sure not 263 to use them. */ 264 static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) 265 { 266 abi_ulong addr, addr1, addr_start; 267 int prot; 268 unsigned long new_brk; 269 270 new_brk = (unsigned long)sbrk(0); 271 if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) { 272 /* This is a hack to catch the host allocating memory with brk(). 273 If it uses mmap then we loose. 274 FIXME: We really want to avoid the host allocating memory in 275 the first place, and maybe leave some slack to avoid switching 276 to mmap. */ 277 page_set_flags(last_brk & TARGET_PAGE_MASK, 278 TARGET_PAGE_ALIGN(new_brk), 279 PAGE_RESERVED); 280 } 281 last_brk = new_brk; 282 283 size = HOST_PAGE_ALIGN(size); 284 start = start & qemu_host_page_mask; 285 addr = start; 286 if (addr == 0) 287 addr = mmap_next_start; 288 addr_start = addr; 289 for(;;) { 290 prot = 0; 291 for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) { 292 prot |= page_get_flags(addr1); 293 } 294 if (prot == 0) 295 break; 296 addr += qemu_host_page_size; 297 /* we found nothing */ 298 if (addr == addr_start) 299 return (abi_ulong)-1; 300 } 301 if (start == 0) 302 mmap_next_start = addr + size; 303 return addr; 304 } 305 306 /* NOTE: all the constants are the HOST ones */ 307 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, 308 int flags, int fd, abi_ulong offset) 309 { 310 abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; 311 unsigned long host_start; 312 313 mmap_lock(); 314 #ifdef DEBUG_MMAP 315 { 316 printf("mmap: start=0x" TARGET_FMT_lx 317 " len=0x" TARGET_FMT_lx " prot=%c%c%c flags=", 318 start, len, 319 prot & PROT_READ ? 'r' : '-', 320 prot & PROT_WRITE ? 'w' : '-', 321 prot & PROT_EXEC ? 'x' : '-'); 322 if (flags & MAP_FIXED) 323 printf("MAP_FIXED "); 324 if (flags & MAP_ANON) 325 printf("MAP_ANON "); 326 switch(flags & MAP_FLAGMASK) { 327 case MAP_PRIVATE: 328 printf("MAP_PRIVATE "); 329 break; 330 case MAP_SHARED: 331 printf("MAP_SHARED "); 332 break; 333 default: 334 printf("[MAP_FLAGMASK=0x%x] ", flags & MAP_FLAGMASK); 335 break; 336 } 337 printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset); 338 } 339 #endif 340 341 if (offset & ~TARGET_PAGE_MASK) { 342 errno = EINVAL; 343 goto fail; 344 } 345 346 len = TARGET_PAGE_ALIGN(len); 347 if (len == 0) 348 goto the_end; 349 real_start = start & qemu_host_page_mask; 350 351 if (!(flags & MAP_FIXED)) { 352 abi_ulong mmap_start; 353 void *p; 354 host_offset = offset & qemu_host_page_mask; 355 host_len = len + offset - host_offset; 356 host_len = HOST_PAGE_ALIGN(host_len); 357 mmap_start = mmap_find_vma(real_start, host_len); 358 if (mmap_start == (abi_ulong)-1) { 359 errno = ENOMEM; 360 goto fail; 361 } 362 /* Note: we prefer to control the mapping address. It is 363 especially important if qemu_host_page_size > 364 qemu_real_host_page_size */ 365 p = mmap(g2h(mmap_start), 366 host_len, prot, flags | MAP_FIXED, fd, host_offset); 367 if (p == MAP_FAILED) 368 goto fail; 369 /* update start so that it points to the file position at 'offset' */ 370 host_start = (unsigned long)p; 371 if (!(flags & MAP_ANON)) 372 host_start += offset - host_offset; 373 start = h2g(host_start); 374 } else { 375 int flg; 376 target_ulong addr; 377 378 if (start & ~TARGET_PAGE_MASK) { 379 errno = EINVAL; 380 goto fail; 381 } 382 end = start + len; 383 real_end = HOST_PAGE_ALIGN(end); 384 385 for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) { 386 flg = page_get_flags(addr); 387 if (flg & PAGE_RESERVED) { 388 errno = ENXIO; 389 goto fail; 390 } 391 } 392 393 /* worst case: we cannot map the file because the offset is not 394 aligned, so we read it */ 395 if (!(flags & MAP_ANON) && 396 (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) { 397 /* msync() won't work here, so we return an error if write is 398 possible while it is a shared mapping */ 399 if ((flags & MAP_FLAGMASK) == MAP_SHARED && 400 (prot & PROT_WRITE)) { 401 errno = EINVAL; 402 goto fail; 403 } 404 retaddr = target_mmap(start, len, prot | PROT_WRITE, 405 MAP_FIXED | MAP_PRIVATE | MAP_ANON, 406 -1, 0); 407 if (retaddr == -1) 408 goto fail; 409 pread(fd, g2h(start), len, offset); 410 if (!(prot & PROT_WRITE)) { 411 ret = target_mprotect(start, len, prot); 412 if (ret != 0) { 413 start = ret; 414 goto the_end; 415 } 416 } 417 goto the_end; 418 } 419 420 /* handle the start of the mapping */ 421 if (start > real_start) { 422 if (real_end == real_start + qemu_host_page_size) { 423 /* one single host page */ 424 ret = mmap_frag(real_start, start, end, 425 prot, flags, fd, offset); 426 if (ret == -1) 427 goto fail; 428 goto the_end1; 429 } 430 ret = mmap_frag(real_start, start, real_start + qemu_host_page_size, 431 prot, flags, fd, offset); 432 if (ret == -1) 433 goto fail; 434 real_start += qemu_host_page_size; 435 } 436 /* handle the end of the mapping */ 437 if (end < real_end) { 438 ret = mmap_frag(real_end - qemu_host_page_size, 439 real_end - qemu_host_page_size, real_end, 440 prot, flags, fd, 441 offset + real_end - qemu_host_page_size - start); 442 if (ret == -1) 443 goto fail; 444 real_end -= qemu_host_page_size; 445 } 446 447 /* map the middle (easier) */ 448 if (real_start < real_end) { 449 void *p; 450 unsigned long offset1; 451 if (flags & MAP_ANON) 452 offset1 = 0; 453 else 454 offset1 = offset + real_start - start; 455 p = mmap(g2h(real_start), real_end - real_start, 456 prot, flags, fd, offset1); 457 if (p == MAP_FAILED) 458 goto fail; 459 } 460 } 461 the_end1: 462 page_set_flags(start, start + len, prot | PAGE_VALID); 463 the_end: 464 #ifdef DEBUG_MMAP 465 printf("ret=0x" TARGET_FMT_lx "\n", start); 466 page_dump(stdout); 467 printf("\n"); 468 #endif 469 mmap_unlock(); 470 return start; 471 fail: 472 mmap_unlock(); 473 return -1; 474 } 475 476 int target_munmap(abi_ulong start, abi_ulong len) 477 { 478 abi_ulong end, real_start, real_end, addr; 479 int prot, ret; 480 481 #ifdef DEBUG_MMAP 482 printf("munmap: start=0x%lx len=0x%lx\n", start, len); 483 #endif 484 if (start & ~TARGET_PAGE_MASK) 485 return -EINVAL; 486 len = TARGET_PAGE_ALIGN(len); 487 if (len == 0) 488 return -EINVAL; 489 mmap_lock(); 490 end = start + len; 491 real_start = start & qemu_host_page_mask; 492 real_end = HOST_PAGE_ALIGN(end); 493 494 if (start > real_start) { 495 /* handle host page containing start */ 496 prot = 0; 497 for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { 498 prot |= page_get_flags(addr); 499 } 500 if (real_end == real_start + qemu_host_page_size) { 501 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 502 prot |= page_get_flags(addr); 503 } 504 end = real_end; 505 } 506 if (prot != 0) 507 real_start += qemu_host_page_size; 508 } 509 if (end < real_end) { 510 prot = 0; 511 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 512 prot |= page_get_flags(addr); 513 } 514 if (prot != 0) 515 real_end -= qemu_host_page_size; 516 } 517 518 ret = 0; 519 /* unmap what we can */ 520 if (real_start < real_end) { 521 ret = munmap(g2h(real_start), real_end - real_start); 522 } 523 524 if (ret == 0) 525 page_set_flags(start, start + len, 0); 526 mmap_unlock(); 527 return ret; 528 } 529 530 int target_msync(abi_ulong start, abi_ulong len, int flags) 531 { 532 abi_ulong end; 533 534 if (start & ~TARGET_PAGE_MASK) 535 return -EINVAL; 536 len = TARGET_PAGE_ALIGN(len); 537 end = start + len; 538 if (end < start) 539 return -EINVAL; 540 if (end == start) 541 return 0; 542 543 start &= qemu_host_page_mask; 544 return msync(g2h(start), end - start, flags); 545 } 546