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 /* NOTE: all the constants are the HOST ones, but addresses are target. */
 126 int target_mprotect(abi_ulong start, abi_ulong len, int prot)
 127 {
 128     abi_ulong end, host_start, host_end, addr;
 129     int prot1, ret;
 130
 131 #ifdef DEBUG_MMAP
 132     printf("mprotect: start=0x" TARGET_FMT_lx
 133            " len=0x" TARGET_FMT_lx " prot=%c%c%c\n", start, len,
 134            prot & PROT_READ ? 'r' : '-',
 135            prot & PROT_WRITE ? 'w' : '-',
 136            prot & PROT_EXEC ? 'x' : '-');
 137 #endif
 138
 139     if ((start & ~TARGET_PAGE_MASK) != 0)
 140         return -EINVAL;
 141     len = TARGET_PAGE_ALIGN(len);
 142     end = start + len;
 143     if (end < start)
 144         return -EINVAL;
 145     prot &= PROT_READ | PROT_WRITE | PROT_EXEC;
 146     if (len == 0)
 147         return 0;
 148
 149     mmap_lock();
 150     host_start = start & qemu_host_page_mask;
 151     host_end = HOST_PAGE_ALIGN(end);
 152     if (start > host_start) {
 153         /* handle host page containing start */
 154         prot1 = prot;
 155         for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
 156             prot1 |= page_get_flags(addr);
 157         }
 158         if (host_end == host_start + qemu_host_page_size) {
 159             for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
 160                 prot1 |= page_get_flags(addr);
 161             }
 162             end = host_end;
 163         }
 164         ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS);
 165         if (ret != 0)
 166             goto error;
 167         host_start += qemu_host_page_size;
 168     }
 169     if (end < host_end) {
 170         prot1 = prot;
 171         for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
 172             prot1 |= page_get_flags(addr);
 173         }
 174         ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size,
 175                        prot1 & PAGE_BITS);
 176         if (ret != 0)
 177             goto error;
 178         host_end -= qemu_host_page_size;
 179     }
 180
 181     /* handle the pages in the middle */
 182     if (host_start < host_end) {
 183         ret = mprotect(g2h(host_start), host_end - host_start, prot);
 184         if (ret != 0)
 185             goto error;
 186     }
 187     page_set_flags(start, start + len, prot | PAGE_VALID);
 188     mmap_unlock();
 189     return 0;
 190 error:
 191     mmap_unlock();
 192     return ret;
 193 }
 194
 195 /* map an incomplete host page */
 196 static int mmap_frag(abi_ulong real_start,
 197                      abi_ulong start, abi_ulong end,
 198                      int prot, int flags, int fd, abi_ulong offset)
 199 {
 200     abi_ulong real_end, addr;
 201     void *host_start;
 202     int prot1, prot_new;
 203
 204     real_end = real_start + qemu_host_page_size;
 205     host_start = g2h(real_start);
 206
 207     /* get the protection of the target pages outside the mapping */
 208     prot1 = 0;
 209     for(addr = real_start; addr < real_end; addr++) {
 210         if (addr < start || addr >= end)
 211             prot1 |= page_get_flags(addr);
 212     }
 213
 214     if (prot1 == 0) {
 215         /* no page was there, so we allocate one */
 216         void *p = mmap(host_start, qemu_host_page_size, prot,
 217                        flags | MAP_ANON, -1, 0);
 218         if (p == MAP_FAILED)
 219             return -1;
 220         prot1 = prot;
 221     }
 222     prot1 &= PAGE_BITS;
 223
 224     prot_new = prot | prot1;
 225     if (!(flags & MAP_ANON)) {
 226         /* msync() won't work here, so we return an error if write is
 227            possible while it is a shared mapping */
 228         if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
 229             (prot & PROT_WRITE))
 230             return -EINVAL;
 231
 232         /* adjust protection to be able to read */
 233         if (!(prot1 & PROT_WRITE))
 234             mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE);
 235
 236         /* read the corresponding file data */
 237         pread(fd, g2h(start), end - start, offset);
 238
 239         /* put final protection */
 240         if (prot_new != (prot1 | PROT_WRITE))
 241             mprotect(host_start, qemu_host_page_size, prot_new);
 242     } else {
 243         /* just update the protection */
 244         if (prot_new != prot1) {
 245             mprotect(host_start, qemu_host_page_size, prot_new);
 246         }
 247     }
 248     return 0;
 249 }
 250
 251 #if defined(__CYGWIN__)
 252 /* Cygwin doesn't have a whole lot of address space.  */
 253 static abi_ulong mmap_next_start = 0x18000000;
 254 #else
 255 static abi_ulong mmap_next_start = 0x40000000;
 256 #endif
 257
 258 unsigned long last_brk;
 259
 260 /* find a free memory area of size 'size'. The search starts at
 261    'start'. If 'start' == 0, then a default start address is used.
 262    Return -1 if error.
 263 */
 264 /* page_init() marks pages used by the host as reserved to be sure not
 265    to use them. */
 266 static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size)
 267 {
 268     abi_ulong addr, addr1, addr_start;
 269     int prot;
 270     unsigned long new_brk;
 271
 272     new_brk = (unsigned long)sbrk(0);
 273     if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) {
 274         /* This is a hack to catch the host allocating memory with brk().
 275            If it uses mmap then we loose.
 276            FIXME: We really want to avoid the host allocating memory in
 277            the first place, and maybe leave some slack to avoid switching
 278            to mmap.  */
 279         page_set_flags(last_brk & TARGET_PAGE_MASK,
 280                        TARGET_PAGE_ALIGN(new_brk),
 281                        PAGE_RESERVED);
 282     }
 283     last_brk = new_brk;
 284
 285     size = HOST_PAGE_ALIGN(size);
 286     start = start & qemu_host_page_mask;
 287     addr = start;
 288     if (addr == 0)
 289         addr = mmap_next_start;
 290     addr_start = addr;
 291     for(;;) {
 292         prot = 0;
 293         for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) {
 294             prot |= page_get_flags(addr1);
 295         }
 296         if (prot == 0)
 297             break;
 298         addr += qemu_host_page_size;
 299         /* we found nothing */
 300         if (addr == addr_start)
 301             return (abi_ulong)-1;
 302     }
 303     if (start == 0)
 304         mmap_next_start = addr + size;
 305     return addr;
 306 }
 307
 308 /* NOTE: all the constants are the HOST ones */
 309 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
 310                      int flags, int fd, abi_ulong offset)
 311 {
 312     abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len;
 313     unsigned long host_start;
 314
 315     mmap_lock();
 316 #ifdef DEBUG_MMAP
 317     {
 318         printf("mmap: start=0x" TARGET_FMT_lx
 319                " len=0x" TARGET_FMT_lx " prot=%c%c%c flags=",
 320                start, len,
 321                prot & PROT_READ ? 'r' : '-',
 322                prot & PROT_WRITE ? 'w' : '-',
 323                prot & PROT_EXEC ? 'x' : '-');
 324         if (flags & MAP_FIXED)
 325             printf("MAP_FIXED ");
 326         if (flags & MAP_ANON)
 327             printf("MAP_ANON ");
 328         switch(flags & TARGET_BSD_MAP_FLAGMASK) {
 329         case MAP_PRIVATE:
 330             printf("MAP_PRIVATE ");
 331             break;
 332         case MAP_SHARED:
 333             printf("MAP_SHARED ");
 334             break;
 335         default:
 336             printf("[MAP_FLAGMASK=0x%x] ", flags & TARGET_BSD_MAP_FLAGMASK);
 337             break;
 338         }
 339         printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset);
 340     }
 341 #endif
 342
 343     if (offset & ~TARGET_PAGE_MASK) {
 344         errno = EINVAL;
 345         goto fail;
 346     }
 347
 348     len = TARGET_PAGE_ALIGN(len);
 349     if (len == 0)
 350         goto the_end;
 351     real_start = start & qemu_host_page_mask;
 352
 353     if (!(flags & MAP_FIXED)) {
 354         abi_ulong mmap_start;
 355         void *p;
 356         host_offset = offset & qemu_host_page_mask;
 357         host_len = len + offset - host_offset;
 358         host_len = HOST_PAGE_ALIGN(host_len);
 359         mmap_start = mmap_find_vma(real_start, host_len);
 360         if (mmap_start == (abi_ulong)-1) {
 361             errno = ENOMEM;
 362             goto fail;
 363         }
 364         /* Note: we prefer to control the mapping address. It is
 365            especially important if qemu_host_page_size >
 366            qemu_real_host_page_size */
 367         p = mmap(g2h(mmap_start),
 368                  host_len, prot, flags | MAP_FIXED, fd, host_offset);
 369         if (p == MAP_FAILED)
 370             goto fail;
 371         /* update start so that it points to the file position at 'offset' */
 372         host_start = (unsigned long)p;
 373         if (!(flags & MAP_ANON))
 374             host_start += offset - host_offset;
 375         start = h2g(host_start);
 376     } else {
 377         int flg;
 378         target_ulong addr;
 379
 380         if (start & ~TARGET_PAGE_MASK) {
 381             errno = EINVAL;
 382             goto fail;
 383         }
 384         end = start + len;
 385         real_end = HOST_PAGE_ALIGN(end);
 386
 387         for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) {
 388             flg = page_get_flags(addr);
 389             if (flg & PAGE_RESERVED) {
 390                 errno = ENXIO;
 391                 goto fail;
 392             }
 393         }
 394
 395         /* worst case: we cannot map the file because the offset is not
 396            aligned, so we read it */
 397         if (!(flags & MAP_ANON) &&
 398             (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) {
 399             /* msync() won't work here, so we return an error if write is
 400                possible while it is a shared mapping */
 401             if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
 402                 (prot & PROT_WRITE)) {
 403                 errno = EINVAL;
 404                 goto fail;
 405             }
 406             retaddr = target_mmap(start, len, prot | PROT_WRITE,
 407                                   MAP_FIXED | MAP_PRIVATE | MAP_ANON,
 408                                   -1, 0);
 409             if (retaddr == -1)
 410                 goto fail;
 411             pread(fd, g2h(start), len, offset);
 412             if (!(prot & PROT_WRITE)) {
 413                 ret = target_mprotect(start, len, prot);
 414                 if (ret != 0) {
 415                     start = ret;
 416                     goto the_end;
 417                 }
 418             }
 419             goto the_end;
 420         }
 421
 422         /* handle the start of the mapping */
 423         if (start > real_start) {
 424             if (real_end == real_start + qemu_host_page_size) {
 425                 /* one single host page */
 426                 ret = mmap_frag(real_start, start, end,
 427                                 prot, flags, fd, offset);
 428                 if (ret == -1)
 429                     goto fail;
 430                 goto the_end1;
 431             }
 432             ret = mmap_frag(real_start, start, real_start + qemu_host_page_size,
 433                             prot, flags, fd, offset);
 434             if (ret == -1)
 435                 goto fail;
 436             real_start += qemu_host_page_size;
 437         }
 438         /* handle the end of the mapping */
 439         if (end < real_end) {
 440             ret = mmap_frag(real_end - qemu_host_page_size,
 441                             real_end - qemu_host_page_size, real_end,
 442                             prot, flags, fd,
 443                             offset + real_end - qemu_host_page_size - start);
 444             if (ret == -1)
 445                 goto fail;
 446             real_end -= qemu_host_page_size;
 447         }
 448
 449         /* map the middle (easier) */
 450         if (real_start < real_end) {
 451             void *p;
 452             unsigned long offset1;
 453             if (flags & MAP_ANON)
 454                 offset1 = 0;
 455             else
 456                 offset1 = offset + real_start - start;
 457             p = mmap(g2h(real_start), real_end - real_start,
 458                      prot, flags, fd, offset1);
 459             if (p == MAP_FAILED)
 460                 goto fail;
 461         }
 462     }
 463  the_end1:
 464     page_set_flags(start, start + len, prot | PAGE_VALID);
 465  the_end:
 466 #ifdef DEBUG_MMAP
 467     printf("ret=0x" TARGET_FMT_lx "\n", start);
 468     page_dump(stdout);
 469     printf("\n");
 470 #endif
 471     mmap_unlock();
 472     return start;
 473 fail:
 474     mmap_unlock();
 475     return -1;
 476 }
 477
 478 int target_munmap(abi_ulong start, abi_ulong len)
 479 {
 480     abi_ulong end, real_start, real_end, addr;
 481     int prot, ret;
 482
 483 #ifdef DEBUG_MMAP
 484     printf("munmap: start=0x%lx len=0x%lx\n", start, len);
 485 #endif
 486     if (start & ~TARGET_PAGE_MASK)
 487         return -EINVAL;
 488     len = TARGET_PAGE_ALIGN(len);
 489     if (len == 0)
 490         return -EINVAL;
 491     mmap_lock();
 492     end = start + len;
 493     real_start = start & qemu_host_page_mask;
 494     real_end = HOST_PAGE_ALIGN(end);
 495
 496     if (start > real_start) {
 497         /* handle host page containing start */
 498         prot = 0;
 499         for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) {
 500             prot |= page_get_flags(addr);
 501         }
 502         if (real_end == real_start + qemu_host_page_size) {
 503             for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
 504                 prot |= page_get_flags(addr);
 505             }
 506             end = real_end;
 507         }
 508         if (prot != 0)
 509             real_start += qemu_host_page_size;
 510     }
 511     if (end < real_end) {
 512         prot = 0;
 513         for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
 514             prot |= page_get_flags(addr);
 515         }
 516         if (prot != 0)
 517             real_end -= qemu_host_page_size;
 518     }
 519
 520     ret = 0;
 521     /* unmap what we can */
 522     if (real_start < real_end) {
 523         ret = munmap(g2h(real_start), real_end - real_start);
 524     }
 525
 526     if (ret == 0)
 527         page_set_flags(start, start + len, 0);
 528     mmap_unlock();
 529     return ret;
 530 }
 531
 532 int target_msync(abi_ulong start, abi_ulong len, int flags)
 533 {
 534     abi_ulong end;
 535
 536     if (start & ~TARGET_PAGE_MASK)
 537         return -EINVAL;
 538     len = TARGET_PAGE_ALIGN(len);
 539     end = start + len;
 540     if (end < start)
 541         return -EINVAL;
 542     if (end == start)
 543         return 0;
 544
 545     start &= qemu_host_page_mask;
 546     return msync(g2h(start), end - start, flags);
 547 }