bsd-user/mmap.c

   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., 51 Franklin Street - Fifth Floor, Boston,
  19  *  MA 02110-1301, USA.
  20  */
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <stdarg.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <errno.h>
  27 #include <sys/mman.h>
  28
  29 #include "qemu.h"
  30 #include "qemu-common.h"
  31 #include "bsd-mman.h"
  32
  33 //#define DEBUG_MMAP
  34
  35 #if defined(USE_NPTL)
  36 pthread_mutex_t mmap_mutex;
  37 static int __thread mmap_lock_count;
  38
  39 void mmap_lock(void)
  40 {
  41     if (mmap_lock_count++ == 0) {
  42         pthread_mutex_lock(&mmap_mutex);
  43     }
  44 }
  45
  46 void mmap_unlock(void)
  47 {
  48     if (--mmap_lock_count == 0) {
  49         pthread_mutex_unlock(&mmap_mutex);
  50     }
  51 }
  52
  53 /* Grab lock to make sure things are in a consistent state after fork().  */
  54 void mmap_fork_start(void)
  55 {
  56     if (mmap_lock_count)
  57         abort();
  58     pthread_mutex_lock(&mmap_mutex);
  59 }
  60
  61 void mmap_fork_end(int child)
  62 {
  63     if (child)
  64         pthread_mutex_init(&mmap_mutex, NULL);
  65     else
  66         pthread_mutex_unlock(&mmap_mutex);
  67 }
  68 #else
  69 /* We aren't threadsafe to start with, so no need to worry about locking.  */
  70 void mmap_lock(void)
  71 {
  72 }
  73
  74 void mmap_unlock(void)
  75 {
  76 }
  77 #endif
  78
  79 void *qemu_vmalloc(size_t size)
  80 {
  81     void *p;
  82     unsigned long addr;
  83     mmap_lock();
  84     /* Use map and mark the pages as used.  */
  85     p = mmap(NULL, size, PROT_READ | PROT_WRITE,
  86              MAP_PRIVATE | MAP_ANON, -1, 0);
  87
  88     addr = (unsigned long)p;
  89     if (addr == (target_ulong) addr) {
  90         /* Allocated region overlaps guest address space.
  91            This may recurse.  */
  92         page_set_flags(addr & TARGET_PAGE_MASK, TARGET_PAGE_ALIGN(addr + size),
  93                        PAGE_RESERVED);
  94     }
  95
  96     mmap_unlock();
  97     return p;
  98 }
  99
 100 void *qemu_malloc(size_t size)
 101 {
 102     char * p;
 103     size += 16;
 104     p = qemu_vmalloc(size);
 105     *(size_t *)p = size;
 106     return p + 16;
 107 }
 108
 109 /* We use map, which is always zero initialized.  */
 110 void * qemu_mallocz(size_t size)
 111 {
 112     return qemu_malloc(size);
 113 }
 114
 115 void qemu_free(void *ptr)
 116 {
 117     /* FIXME: We should unmark the reserved pages here.  However this gets
 118        complicated when one target page spans multiple host pages, so we
 119        don't bother.  */
 120     size_t *p;
 121     p = (size_t *)((char *)ptr - 16);
 122     munmap(p, *p);
 123 }
 124
 125 void *qemu_realloc(void *ptr, size_t size)
 126 {
 127     size_t old_size, copy;
 128     void *new_ptr;
 129
 130     if (!ptr)
 131         return qemu_malloc(size);
 132     old_size = *(size_t *)((char *)ptr - 16);
 133     copy = old_size < size ? old_size : size;
 134     new_ptr = qemu_malloc(size);
 135     memcpy(new_ptr, ptr, copy);
 136     qemu_free(ptr);
 137     return new_ptr;
 138 }
 139
 140 /* NOTE: all the constants are the HOST ones, but addresses are target. */
 141 int target_mprotect(abi_ulong start, abi_ulong len, int prot)
 142 {
 143     abi_ulong end, host_start, host_end, addr;
 144     int prot1, ret;
 145
 146 #ifdef DEBUG_MMAP
 147     printf("mprotect: start=0x" TARGET_FMT_lx
 148            " len=0x" TARGET_FMT_lx " prot=%c%c%c\n", start, len,
 149            prot & PROT_READ ? 'r' : '-',
 150            prot & PROT_WRITE ? 'w' : '-',
 151            prot & PROT_EXEC ? 'x' : '-');
 152 #endif
 153
 154     if ((start & ~TARGET_PAGE_MASK) != 0)
 155         return -EINVAL;
 156     len = TARGET_PAGE_ALIGN(len);
 157     end = start + len;
 158     if (end < start)
 159         return -EINVAL;
 160     prot &= PROT_READ | PROT_WRITE | PROT_EXEC;
 161     if (len == 0)
 162         return 0;
 163
 164     mmap_lock();
 165     host_start = start & qemu_host_page_mask;
 166     host_end = HOST_PAGE_ALIGN(end);
 167     if (start > host_start) {
 168         /* handle host page containing start */
 169         prot1 = prot;
 170         for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
 171             prot1 |= page_get_flags(addr);
 172         }
 173         if (host_end == host_start + qemu_host_page_size) {
 174             for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
 175                 prot1 |= page_get_flags(addr);
 176             }
 177             end = host_end;
 178         }
 179         ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS);
 180         if (ret != 0)
 181             goto error;
 182         host_start += qemu_host_page_size;
 183     }
 184     if (end < host_end) {
 185         prot1 = prot;
 186         for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
 187             prot1 |= page_get_flags(addr);
 188         }
 189         ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size,
 190                        prot1 & PAGE_BITS);
 191         if (ret != 0)
 192             goto error;
 193         host_end -= qemu_host_page_size;
 194     }
 195
 196     /* handle the pages in the middle */
 197     if (host_start < host_end) {
 198         ret = mprotect(g2h(host_start), host_end - host_start, prot);
 199         if (ret != 0)
 200             goto error;
 201     }
 202     page_set_flags(start, start + len, prot | PAGE_VALID);
 203     mmap_unlock();
 204     return 0;
 205 error:
 206     mmap_unlock();
 207     return ret;
 208 }
 209
 210 /* map an incomplete host page */
 211 static int mmap_frag(abi_ulong real_start,
 212                      abi_ulong start, abi_ulong end,
 213                      int prot, int flags, int fd, abi_ulong offset)
 214 {
 215     abi_ulong real_end, addr;
 216     void *host_start;
 217     int prot1, prot_new;
 218
 219     real_end = real_start + qemu_host_page_size;
 220     host_start = g2h(real_start);
 221
 222     /* get the protection of the target pages outside the mapping */
 223     prot1 = 0;
 224     for(addr = real_start; addr < real_end; addr++) {
 225         if (addr < start || addr >= end)
 226             prot1 |= page_get_flags(addr);
 227     }
 228
 229     if (prot1 == 0) {
 230         /* no page was there, so we allocate one */
 231         void *p = mmap(host_start, qemu_host_page_size, prot,
 232                        flags | MAP_ANON, -1, 0);
 233         if (p == MAP_FAILED)
 234             return -1;
 235         prot1 = prot;
 236     }
 237     prot1 &= PAGE_BITS;
 238
 239     prot_new = prot | prot1;
 240     if (!(flags & MAP_ANON)) {
 241         /* msync() won't work here, so we return an error if write is
 242            possible while it is a shared mapping */
 243         if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
 244             (prot & PROT_WRITE))
 245             return -EINVAL;
 246
 247         /* adjust protection to be able to read */
 248         if (!(prot1 & PROT_WRITE))
 249             mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE);
 250
 251         /* read the corresponding file data */
 252         pread(fd, g2h(start), end - start, offset);
 253
 254         /* put final protection */
 255         if (prot_new != (prot1 | PROT_WRITE))
 256             mprotect(host_start, qemu_host_page_size, prot_new);
 257     } else {
 258         /* just update the protection */
 259         if (prot_new != prot1) {
 260             mprotect(host_start, qemu_host_page_size, prot_new);
 261         }
 262     }
 263     return 0;
 264 }
 265
 266 #if defined(__CYGWIN__)
 267 /* Cygwin doesn't have a whole lot of address space.  */
 268 static abi_ulong mmap_next_start = 0x18000000;
 269 #else
 270 static abi_ulong mmap_next_start = 0x40000000;
 271 #endif
 272
 273 unsigned long last_brk;
 274
 275 /* find a free memory area of size 'size'. The search starts at
 276    'start'. If 'start' == 0, then a default start address is used.
 277    Return -1 if error.
 278 */
 279 /* page_init() marks pages used by the host as reserved to be sure not
 280    to use them. */
 281 static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size)
 282 {
 283     abi_ulong addr, addr1, addr_start;
 284     int prot;
 285     unsigned long new_brk;
 286
 287     new_brk = (unsigned long)sbrk(0);
 288     if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) {
 289         /* This is a hack to catch the host allocating memory with brk().
 290            If it uses mmap then we loose.
 291            FIXME: We really want to avoid the host allocating memory in
 292            the first place, and maybe leave some slack to avoid switching
 293            to mmap.  */
 294         page_set_flags(last_brk & TARGET_PAGE_MASK,
 295                        TARGET_PAGE_ALIGN(new_brk),
 296                        PAGE_RESERVED);
 297     }
 298     last_brk = new_brk;
 299
 300     size = HOST_PAGE_ALIGN(size);
 301     start = start & qemu_host_page_mask;
 302     addr = start;
 303     if (addr == 0)
 304         addr = mmap_next_start;
 305     addr_start = addr;
 306     for(;;) {
 307         prot = 0;
 308         for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) {
 309             prot |= page_get_flags(addr1);
 310         }
 311         if (prot == 0)
 312             break;
 313         addr += qemu_host_page_size;
 314         /* we found nothing */
 315         if (addr == addr_start)
 316             return (abi_ulong)-1;
 317     }
 318     if (start == 0)
 319         mmap_next_start = addr + size;
 320     return addr;
 321 }
 322
 323 /* NOTE: all the constants are the HOST ones */
 324 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
 325                      int flags, int fd, abi_ulong offset)
 326 {
 327     abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len;
 328     unsigned long host_start;
 329
 330     mmap_lock();
 331 #ifdef DEBUG_MMAP
 332     {
 333         printf("mmap: start=0x" TARGET_FMT_lx
 334                " len=0x" TARGET_FMT_lx " prot=%c%c%c flags=",
 335                start, len,
 336                prot & PROT_READ ? 'r' : '-',
 337                prot & PROT_WRITE ? 'w' : '-',
 338                prot & PROT_EXEC ? 'x' : '-');
 339         if (flags & MAP_FIXED)
 340             printf("MAP_FIXED ");
 341         if (flags & MAP_ANON)
 342             printf("MAP_ANON ");
 343         switch(flags & TARGET_BSD_MAP_FLAGMASK) {
 344         case MAP_PRIVATE:
 345             printf("MAP_PRIVATE ");
 346             break;
 347         case MAP_SHARED:
 348             printf("MAP_SHARED ");
 349             break;
 350         default:
 351             printf("[MAP_FLAGMASK=0x%x] ", flags & TARGET_BSD_MAP_FLAGMASK);
 352             break;
 353         }
 354         printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset);
 355     }
 356 #endif
 357
 358     if (offset & ~TARGET_PAGE_MASK) {
 359         errno = EINVAL;
 360         goto fail;
 361     }
 362
 363     len = TARGET_PAGE_ALIGN(len);
 364     if (len == 0)
 365         goto the_end;
 366     real_start = start & qemu_host_page_mask;
 367
 368     if (!(flags & MAP_FIXED)) {
 369         abi_ulong mmap_start;
 370         void *p;
 371         host_offset = offset & qemu_host_page_mask;
 372         host_len = len + offset - host_offset;
 373         host_len = HOST_PAGE_ALIGN(host_len);
 374         mmap_start = mmap_find_vma(real_start, host_len);
 375         if (mmap_start == (abi_ulong)-1) {
 376             errno = ENOMEM;
 377             goto fail;
 378         }
 379         /* Note: we prefer to control the mapping address. It is
 380            especially important if qemu_host_page_size >
 381            qemu_real_host_page_size */
 382         p = mmap(g2h(mmap_start),
 383                  host_len, prot, flags | MAP_FIXED, fd, host_offset);
 384         if (p == MAP_FAILED)
 385             goto fail;
 386         /* update start so that it points to the file position at 'offset' */
 387         host_start = (unsigned long)p;
 388         if (!(flags & MAP_ANON))
 389             host_start += offset - host_offset;
 390         start = h2g(host_start);
 391     } else {
 392         int flg;
 393         target_ulong addr;
 394
 395         if (start & ~TARGET_PAGE_MASK) {
 396             errno = EINVAL;
 397             goto fail;
 398         }
 399         end = start + len;
 400         real_end = HOST_PAGE_ALIGN(end);
 401
 402         for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) {
 403             flg = page_get_flags(addr);
 404             if (flg & PAGE_RESERVED) {
 405                 errno = ENXIO;
 406                 goto fail;
 407             }
 408         }
 409
 410         /* worst case: we cannot map the file because the offset is not
 411            aligned, so we read it */
 412         if (!(flags & MAP_ANON) &&
 413             (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) {
 414             /* msync() won't work here, so we return an error if write is
 415                possible while it is a shared mapping */
 416             if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
 417                 (prot & PROT_WRITE)) {
 418                 errno = EINVAL;
 419                 goto fail;
 420             }
 421             retaddr = target_mmap(start, len, prot | PROT_WRITE,
 422                                   MAP_FIXED | MAP_PRIVATE | MAP_ANON,
 423                                   -1, 0);
 424             if (retaddr == -1)
 425                 goto fail;
 426             pread(fd, g2h(start), len, offset);
 427             if (!(prot & PROT_WRITE)) {
 428                 ret = target_mprotect(start, len, prot);
 429                 if (ret != 0) {
 430                     start = ret;
 431                     goto the_end;
 432                 }
 433             }
 434             goto the_end;
 435         }
 436
 437         /* handle the start of the mapping */
 438         if (start > real_start) {
 439             if (real_end == real_start + qemu_host_page_size) {
 440                 /* one single host page */
 441                 ret = mmap_frag(real_start, start, end,
 442                                 prot, flags, fd, offset);
 443                 if (ret == -1)
 444                     goto fail;
 445                 goto the_end1;
 446             }
 447             ret = mmap_frag(real_start, start, real_start + qemu_host_page_size,
 448                             prot, flags, fd, offset);
 449             if (ret == -1)
 450                 goto fail;
 451             real_start += qemu_host_page_size;
 452         }
 453         /* handle the end of the mapping */
 454         if (end < real_end) {
 455             ret = mmap_frag(real_end - qemu_host_page_size,
 456                             real_end - qemu_host_page_size, real_end,
 457                             prot, flags, fd,
 458                             offset + real_end - qemu_host_page_size - start);
 459             if (ret == -1)
 460                 goto fail;
 461             real_end -= qemu_host_page_size;
 462         }
 463
 464         /* map the middle (easier) */
 465         if (real_start < real_end) {
 466             void *p;
 467             unsigned long offset1;
 468             if (flags & MAP_ANON)
 469                 offset1 = 0;
 470             else
 471                 offset1 = offset + real_start - start;
 472             p = mmap(g2h(real_start), real_end - real_start,
 473                      prot, flags, fd, offset1);
 474             if (p == MAP_FAILED)
 475                 goto fail;
 476         }
 477     }
 478  the_end1:
 479     page_set_flags(start, start + len, prot | PAGE_VALID);
 480  the_end:
 481 #ifdef DEBUG_MMAP
 482     printf("ret=0x" TARGET_FMT_lx "\n", start);
 483     page_dump(stdout);
 484     printf("\n");
 485 #endif
 486     mmap_unlock();
 487     return start;
 488 fail:
 489     mmap_unlock();
 490     return -1;
 491 }
 492
 493 int target_munmap(abi_ulong start, abi_ulong len)
 494 {
 495     abi_ulong end, real_start, real_end, addr;
 496     int prot, ret;
 497
 498 #ifdef DEBUG_MMAP
 499     printf("munmap: start=0x%lx len=0x%lx\n", start, len);
 500 #endif
 501     if (start & ~TARGET_PAGE_MASK)
 502         return -EINVAL;
 503     len = TARGET_PAGE_ALIGN(len);
 504     if (len == 0)
 505         return -EINVAL;
 506     mmap_lock();
 507     end = start + len;
 508     real_start = start & qemu_host_page_mask;
 509     real_end = HOST_PAGE_ALIGN(end);
 510
 511     if (start > real_start) {
 512         /* handle host page containing start */
 513         prot = 0;
 514         for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) {
 515             prot |= page_get_flags(addr);
 516         }
 517         if (real_end == real_start + qemu_host_page_size) {
 518             for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
 519                 prot |= page_get_flags(addr);
 520             }
 521             end = real_end;
 522         }
 523         if (prot != 0)
 524             real_start += qemu_host_page_size;
 525     }
 526     if (end < real_end) {
 527         prot = 0;
 528         for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
 529             prot |= page_get_flags(addr);
 530         }
 531         if (prot != 0)
 532             real_end -= qemu_host_page_size;
 533     }
 534
 535     ret = 0;
 536     /* unmap what we can */
 537     if (real_start < real_end) {
 538         ret = munmap(g2h(real_start), real_end - real_start);
 539     }
 540
 541     if (ret == 0)
 542         page_set_flags(start, start + len, 0);
 543     mmap_unlock();
 544     return ret;
 545 }
 546
 547 int target_msync(abi_ulong start, abi_ulong len, int flags)
 548 {
 549     abi_ulong end;
 550
 551     if (start & ~TARGET_PAGE_MASK)
 552         return -EINVAL;
 553     len = TARGET_PAGE_ALIGN(len);
 554     end = start + len;
 555     if (end < start)
 556         return -EINVAL;
 557     if (end == start)
 558         return 0;
 559
 560     start &= qemu_host_page_mask;
 561     return msync(g2h(start), end - start, flags);
 562 }