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