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, 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 void *qemu_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 *qemu_malloc(size_t size)
  98 {
  99     char * p;
 100     size += 16;
 101     p = qemu_vmalloc(size);
 102     *(size_t *)p = size;
 103     return p + 16;
 104 }
 105
 106 /* We use map, which is always zero initialized.  */
 107 void * qemu_mallocz(size_t size)
 108 {
 109     return qemu_malloc(size);
 110 }
 111
 112 void qemu_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 *qemu_realloc(void *ptr, size_t size)
 123 {
 124     size_t old_size, copy;
 125     void *new_ptr;
 126
 127     if (!ptr)
 128         return qemu_malloc(size);
 129     old_size = *(size_t *)((char *)ptr - 16);
 130     copy = old_size < size ? old_size : size;
 131     new_ptr = qemu_malloc(size);
 132     memcpy(new_ptr, ptr, copy);
 133     qemu_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 }