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 #include "qemu-common.h" 23 #include "bsd-mman.h" 24 #include "exec/exec-all.h" 25 26 //#define DEBUG_MMAP 27 28 static pthread_mutex_t mmap_mutex = PTHREAD_MUTEX_INITIALIZER; 29 static __thread int mmap_lock_count; 30 31 void mmap_lock(void) 32 { 33 if (mmap_lock_count++ == 0) { 34 pthread_mutex_lock(&mmap_mutex); 35 } 36 } 37 38 void mmap_unlock(void) 39 { 40 if (--mmap_lock_count == 0) { 41 pthread_mutex_unlock(&mmap_mutex); 42 } 43 } 44 45 bool have_mmap_lock(void) 46 { 47 return mmap_lock_count > 0 ? true : false; 48 } 49 50 /* Grab lock to make sure things are in a consistent state after fork(). */ 51 void mmap_fork_start(void) 52 { 53 if (mmap_lock_count) 54 abort(); 55 pthread_mutex_lock(&mmap_mutex); 56 } 57 58 void mmap_fork_end(int child) 59 { 60 if (child) 61 pthread_mutex_init(&mmap_mutex, NULL); 62 else 63 pthread_mutex_unlock(&mmap_mutex); 64 } 65 66 /* NOTE: all the constants are the HOST ones, but addresses are target. */ 67 int target_mprotect(abi_ulong start, abi_ulong len, int prot) 68 { 69 abi_ulong end, host_start, host_end, addr; 70 int prot1, ret; 71 72 #ifdef DEBUG_MMAP 73 printf("mprotect: start=0x" TARGET_FMT_lx 74 " len=0x" TARGET_FMT_lx " prot=%c%c%c\n", start, len, 75 prot & PROT_READ ? 'r' : '-', 76 prot & PROT_WRITE ? 'w' : '-', 77 prot & PROT_EXEC ? 'x' : '-'); 78 #endif 79 80 if ((start & ~TARGET_PAGE_MASK) != 0) 81 return -EINVAL; 82 len = TARGET_PAGE_ALIGN(len); 83 end = start + len; 84 if (end < start) 85 return -EINVAL; 86 prot &= PROT_READ | PROT_WRITE | PROT_EXEC; 87 if (len == 0) 88 return 0; 89 90 mmap_lock(); 91 host_start = start & qemu_host_page_mask; 92 host_end = HOST_PAGE_ALIGN(end); 93 if (start > host_start) { 94 /* handle host page containing start */ 95 prot1 = prot; 96 for (addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) { 97 prot1 |= page_get_flags(addr); 98 } 99 if (host_end == host_start + qemu_host_page_size) { 100 for (addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 101 prot1 |= page_get_flags(addr); 102 } 103 end = host_end; 104 } 105 ret = mprotect(g2h_untagged(host_start), 106 qemu_host_page_size, prot1 & PAGE_BITS); 107 if (ret != 0) 108 goto error; 109 host_start += qemu_host_page_size; 110 } 111 if (end < host_end) { 112 prot1 = prot; 113 for (addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { 114 prot1 |= page_get_flags(addr); 115 } 116 ret = mprotect(g2h_untagged(host_end - qemu_host_page_size), 117 qemu_host_page_size, prot1 & PAGE_BITS); 118 if (ret != 0) 119 goto error; 120 host_end -= qemu_host_page_size; 121 } 122 123 /* handle the pages in the middle */ 124 if (host_start < host_end) { 125 ret = mprotect(g2h_untagged(host_start), host_end - host_start, prot); 126 if (ret != 0) 127 goto error; 128 } 129 page_set_flags(start, start + len, prot | PAGE_VALID); 130 mmap_unlock(); 131 return 0; 132 error: 133 mmap_unlock(); 134 return ret; 135 } 136 137 /* map an incomplete host page */ 138 static int mmap_frag(abi_ulong real_start, 139 abi_ulong start, abi_ulong end, 140 int prot, int flags, int fd, abi_ulong offset) 141 { 142 abi_ulong real_end, addr; 143 void *host_start; 144 int prot1, prot_new; 145 146 real_end = real_start + qemu_host_page_size; 147 host_start = g2h_untagged(real_start); 148 149 /* get the protection of the target pages outside the mapping */ 150 prot1 = 0; 151 for (addr = real_start; addr < real_end; addr++) { 152 if (addr < start || addr >= end) 153 prot1 |= page_get_flags(addr); 154 } 155 156 if (prot1 == 0) { 157 /* no page was there, so we allocate one */ 158 void *p = mmap(host_start, qemu_host_page_size, prot, 159 flags | MAP_ANON, -1, 0); 160 if (p == MAP_FAILED) 161 return -1; 162 prot1 = prot; 163 } 164 prot1 &= PAGE_BITS; 165 166 prot_new = prot | prot1; 167 if (!(flags & MAP_ANON)) { 168 /* msync() won't work here, so we return an error if write is 169 possible while it is a shared mapping */ 170 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && 171 (prot & PROT_WRITE)) 172 return -1; 173 174 /* adjust protection to be able to read */ 175 if (!(prot1 & PROT_WRITE)) 176 mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE); 177 178 /* read the corresponding file data */ 179 pread(fd, g2h_untagged(start), end - start, offset); 180 181 /* put final protection */ 182 if (prot_new != (prot1 | PROT_WRITE)) 183 mprotect(host_start, qemu_host_page_size, prot_new); 184 } else { 185 /* just update the protection */ 186 if (prot_new != prot1) { 187 mprotect(host_start, qemu_host_page_size, prot_new); 188 } 189 } 190 return 0; 191 } 192 193 static abi_ulong mmap_next_start = 0x40000000; 194 195 unsigned long last_brk; 196 197 /* find a free memory area of size 'size'. The search starts at 198 'start'. If 'start' == 0, then a default start address is used. 199 Return -1 if error. 200 */ 201 /* page_init() marks pages used by the host as reserved to be sure not 202 to use them. */ 203 static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) 204 { 205 abi_ulong addr, addr1, addr_start; 206 int prot; 207 unsigned long new_brk; 208 209 new_brk = (unsigned long)sbrk(0); 210 if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) { 211 /* This is a hack to catch the host allocating memory with brk(). 212 If it uses mmap then we loose. 213 FIXME: We really want to avoid the host allocating memory in 214 the first place, and maybe leave some slack to avoid switching 215 to mmap. */ 216 page_set_flags(last_brk & TARGET_PAGE_MASK, 217 TARGET_PAGE_ALIGN(new_brk), 218 PAGE_RESERVED); 219 } 220 last_brk = new_brk; 221 222 size = HOST_PAGE_ALIGN(size); 223 start = start & qemu_host_page_mask; 224 addr = start; 225 if (addr == 0) 226 addr = mmap_next_start; 227 addr_start = addr; 228 for (;;) { 229 prot = 0; 230 for (addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) { 231 prot |= page_get_flags(addr1); 232 } 233 if (prot == 0) 234 break; 235 addr += qemu_host_page_size; 236 /* we found nothing */ 237 if (addr == addr_start) 238 return (abi_ulong)-1; 239 } 240 if (start == 0) 241 mmap_next_start = addr + size; 242 return addr; 243 } 244 245 /* NOTE: all the constants are the HOST ones */ 246 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, 247 int flags, int fd, abi_ulong offset) 248 { 249 abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; 250 unsigned long host_start; 251 252 mmap_lock(); 253 #ifdef DEBUG_MMAP 254 { 255 printf("mmap: start=0x" TARGET_FMT_lx 256 " len=0x" TARGET_FMT_lx " prot=%c%c%c flags=", 257 start, len, 258 prot & PROT_READ ? 'r' : '-', 259 prot & PROT_WRITE ? 'w' : '-', 260 prot & PROT_EXEC ? 'x' : '-'); 261 if (flags & MAP_FIXED) 262 printf("MAP_FIXED "); 263 if (flags & MAP_ANON) 264 printf("MAP_ANON "); 265 switch (flags & TARGET_BSD_MAP_FLAGMASK) { 266 case MAP_PRIVATE: 267 printf("MAP_PRIVATE "); 268 break; 269 case MAP_SHARED: 270 printf("MAP_SHARED "); 271 break; 272 default: 273 printf("[MAP_FLAGMASK=0x%x] ", flags & TARGET_BSD_MAP_FLAGMASK); 274 break; 275 } 276 printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset); 277 } 278 #endif 279 280 if (offset & ~TARGET_PAGE_MASK) { 281 errno = EINVAL; 282 goto fail; 283 } 284 285 len = TARGET_PAGE_ALIGN(len); 286 if (len == 0) 287 goto the_end; 288 real_start = start & qemu_host_page_mask; 289 290 if (!(flags & MAP_FIXED)) { 291 abi_ulong mmap_start; 292 void *p; 293 host_offset = offset & qemu_host_page_mask; 294 host_len = len + offset - host_offset; 295 host_len = HOST_PAGE_ALIGN(host_len); 296 mmap_start = mmap_find_vma(real_start, host_len); 297 if (mmap_start == (abi_ulong)-1) { 298 errno = ENOMEM; 299 goto fail; 300 } 301 /* Note: we prefer to control the mapping address. It is 302 especially important if qemu_host_page_size > 303 qemu_real_host_page_size */ 304 p = mmap(g2h_untagged(mmap_start), 305 host_len, prot, flags | MAP_FIXED, fd, host_offset); 306 if (p == MAP_FAILED) 307 goto fail; 308 /* update start so that it points to the file position at 'offset' */ 309 host_start = (unsigned long)p; 310 if (!(flags & MAP_ANON)) 311 host_start += offset - host_offset; 312 start = h2g(host_start); 313 } else { 314 int flg; 315 target_ulong addr; 316 317 if (start & ~TARGET_PAGE_MASK) { 318 errno = EINVAL; 319 goto fail; 320 } 321 end = start + len; 322 real_end = HOST_PAGE_ALIGN(end); 323 324 for (addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) { 325 flg = page_get_flags(addr); 326 if (flg & PAGE_RESERVED) { 327 errno = ENXIO; 328 goto fail; 329 } 330 } 331 332 /* worst case: we cannot map the file because the offset is not 333 aligned, so we read it */ 334 if (!(flags & MAP_ANON) && 335 (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) { 336 /* msync() won't work here, so we return an error if write is 337 possible while it is a shared mapping */ 338 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && 339 (prot & PROT_WRITE)) { 340 errno = EINVAL; 341 goto fail; 342 } 343 retaddr = target_mmap(start, len, prot | PROT_WRITE, 344 MAP_FIXED | MAP_PRIVATE | MAP_ANON, 345 -1, 0); 346 if (retaddr == -1) 347 goto fail; 348 pread(fd, g2h_untagged(start), len, offset); 349 if (!(prot & PROT_WRITE)) { 350 ret = target_mprotect(start, len, prot); 351 if (ret != 0) { 352 start = ret; 353 goto the_end; 354 } 355 } 356 goto the_end; 357 } 358 359 /* handle the start of the mapping */ 360 if (start > real_start) { 361 if (real_end == real_start + qemu_host_page_size) { 362 /* one single host page */ 363 ret = mmap_frag(real_start, start, end, 364 prot, flags, fd, offset); 365 if (ret == -1) 366 goto fail; 367 goto the_end1; 368 } 369 ret = mmap_frag(real_start, start, real_start + qemu_host_page_size, 370 prot, flags, fd, offset); 371 if (ret == -1) 372 goto fail; 373 real_start += qemu_host_page_size; 374 } 375 /* handle the end of the mapping */ 376 if (end < real_end) { 377 ret = mmap_frag(real_end - qemu_host_page_size, 378 real_end - qemu_host_page_size, real_end, 379 prot, flags, fd, 380 offset + real_end - qemu_host_page_size - start); 381 if (ret == -1) 382 goto fail; 383 real_end -= qemu_host_page_size; 384 } 385 386 /* map the middle (easier) */ 387 if (real_start < real_end) { 388 void *p; 389 unsigned long offset1; 390 if (flags & MAP_ANON) 391 offset1 = 0; 392 else 393 offset1 = offset + real_start - start; 394 p = mmap(g2h_untagged(real_start), real_end - real_start, 395 prot, flags, fd, offset1); 396 if (p == MAP_FAILED) 397 goto fail; 398 } 399 } 400 the_end1: 401 page_set_flags(start, start + len, prot | PAGE_VALID); 402 the_end: 403 #ifdef DEBUG_MMAP 404 printf("ret=0x" TARGET_FMT_lx "\n", start); 405 page_dump(stdout); 406 printf("\n"); 407 #endif 408 mmap_unlock(); 409 return start; 410 fail: 411 mmap_unlock(); 412 return -1; 413 } 414 415 int target_munmap(abi_ulong start, abi_ulong len) 416 { 417 abi_ulong end, real_start, real_end, addr; 418 int prot, ret; 419 420 #ifdef DEBUG_MMAP 421 printf("munmap: start=0x%lx len=0x%lx\n", start, len); 422 #endif 423 if (start & ~TARGET_PAGE_MASK) 424 return -EINVAL; 425 len = TARGET_PAGE_ALIGN(len); 426 if (len == 0) 427 return -EINVAL; 428 mmap_lock(); 429 end = start + len; 430 real_start = start & qemu_host_page_mask; 431 real_end = HOST_PAGE_ALIGN(end); 432 433 if (start > real_start) { 434 /* handle host page containing start */ 435 prot = 0; 436 for (addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { 437 prot |= page_get_flags(addr); 438 } 439 if (real_end == real_start + qemu_host_page_size) { 440 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 441 prot |= page_get_flags(addr); 442 } 443 end = real_end; 444 } 445 if (prot != 0) 446 real_start += qemu_host_page_size; 447 } 448 if (end < real_end) { 449 prot = 0; 450 for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { 451 prot |= page_get_flags(addr); 452 } 453 if (prot != 0) 454 real_end -= qemu_host_page_size; 455 } 456 457 ret = 0; 458 /* unmap what we can */ 459 if (real_start < real_end) { 460 ret = munmap(g2h_untagged(real_start), real_end - real_start); 461 } 462 463 if (ret == 0) 464 page_set_flags(start, start + len, 0); 465 mmap_unlock(); 466 return ret; 467 } 468 469 int target_msync(abi_ulong start, abi_ulong len, int flags) 470 { 471 abi_ulong end; 472 473 if (start & ~TARGET_PAGE_MASK) 474 return -EINVAL; 475 len = TARGET_PAGE_ALIGN(len); 476 end = start + len; 477 if (end < start) 478 return -EINVAL; 479 if (end == start) 480 return 0; 481 482 start &= qemu_host_page_mask; 483 return msync(g2h_untagged(start), end - start, flags); 484 } 485