linux-user/mmap.c

   1 /*
   2  *  mmap support for qemu
   3  *
   4  *  Copyright (c) 2003 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., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20 #include <stdlib.h>
  21 #include <stdio.h>
  22 #include <stdarg.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <errno.h>
  26 #include <sys/mman.h>
  27
  28 #include "qemu.h"
  29
  30 //#define DEBUG_MMAP
  31
  32 /* NOTE: all the constants are the HOST ones, but addresses are target. */
  33 int target_mprotect(target_ulong start, target_ulong len, int prot)
  34 {
  35     target_ulong end, host_start, host_end, addr;
  36     int prot1, ret;
  37
  38 #ifdef DEBUG_MMAP
  39     printf("mprotect: start=0x%lx len=0x%lx prot=%c%c%c\n", start, len,
  40            prot & PROT_READ ? 'r' : '-',
  41            prot & PROT_WRITE ? 'w' : '-',
  42            prot & PROT_EXEC ? 'x' : '-');
  43 #endif
  44
  45     if ((start & ~TARGET_PAGE_MASK) != 0)
  46         return -EINVAL;
  47     len = TARGET_PAGE_ALIGN(len);
  48     end = start + len;
  49     if (end < start)
  50         return -EINVAL;
  51     if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC))
  52         return -EINVAL;
  53     if (len == 0)
  54         return 0;
  55
  56     host_start = start & qemu_host_page_mask;
  57     host_end = HOST_PAGE_ALIGN(end);
  58     if (start > host_start) {
  59         /* handle host page containing start */
  60         prot1 = prot;
  61         for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
  62             prot1 |= page_get_flags(addr);
  63         }
  64         if (host_end == host_start + qemu_host_page_size) {
  65             for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
  66                 prot1 |= page_get_flags(addr);
  67             }
  68             end = host_end;
  69         }
  70         ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS);
  71         if (ret != 0)
  72             return ret;
  73         host_start += qemu_host_page_size;
  74     }
  75     if (end < host_end) {
  76         prot1 = prot;
  77         for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
  78             prot1 |= page_get_flags(addr);
  79         }
  80         ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size,
  81                        prot1 & PAGE_BITS);
  82         if (ret != 0)
  83             return ret;
  84         host_end -= qemu_host_page_size;
  85     }
  86
  87     /* handle the pages in the middle */
  88     if (host_start < host_end) {
  89         ret = mprotect(g2h(host_start), host_end - host_start, prot);
  90         if (ret != 0)
  91             return ret;
  92     }
  93     page_set_flags(start, start + len, prot | PAGE_VALID);
  94     return 0;
  95 }
  96
  97 /* map an incomplete host page */
  98 static int mmap_frag(target_ulong real_start,
  99                      target_ulong start, target_ulong end,
 100                      int prot, int flags, int fd, target_ulong offset)
 101 {
 102     target_ulong real_end, ret, addr;
 103     void *host_start;
 104     int prot1, prot_new;
 105
 106     real_end = real_start + qemu_host_page_size;
 107     host_start = g2h(real_start);
 108
 109     /* get the protection of the target pages outside the mapping */
 110     prot1 = 0;
 111     for(addr = real_start; addr < real_end; addr++) {
 112         if (addr < start || addr >= end)
 113             prot1 |= page_get_flags(addr);
 114     }
 115
 116     if (prot1 == 0) {
 117         /* no page was there, so we allocate one */
 118         ret = (long)mmap(host_start, qemu_host_page_size, prot,
 119                          flags | MAP_ANONYMOUS, -1, 0);
 120         if (ret == -1)
 121             return ret;
 122         prot1 = prot;
 123     }
 124     prot1 &= PAGE_BITS;
 125
 126     prot_new = prot | prot1;
 127     if (!(flags & MAP_ANONYMOUS)) {
 128         /* msync() won't work here, so we return an error if write is
 129            possible while it is a shared mapping */
 130         if ((flags & MAP_TYPE) == MAP_SHARED &&
 131             (prot & PROT_WRITE))
 132             return -EINVAL;
 133
 134         /* adjust protection to be able to read */
 135         if (!(prot1 & PROT_WRITE))
 136             mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE);
 137
 138         /* read the corresponding file data */
 139         pread(fd, g2h(start), end - start, offset);
 140
 141         /* put final protection */
 142         if (prot_new != (prot1 | PROT_WRITE))
 143             mprotect(host_start, qemu_host_page_size, prot_new);
 144     } else {
 145         /* just update the protection */
 146         if (prot_new != prot1) {
 147             mprotect(host_start, qemu_host_page_size, prot_new);
 148         }
 149     }
 150     return 0;
 151 }
 152
 153 /* NOTE: all the constants are the HOST ones */
 154 long target_mmap(target_ulong start, target_ulong len, int prot,
 155                  int flags, int fd, target_ulong offset)
 156 {
 157     target_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len;
 158     long host_start;
 159 #if defined(__alpha__) || defined(__sparc__) || defined(__x86_64__) || \
 160         defined(__ia64) || defined(__mips__)
 161     static target_ulong last_start = 0x40000000;
 162 #elif defined(__CYGWIN__)
 163     /* Cygwin doesn't have a whole lot of address space.  */
 164     static target_ulong last_start = 0x18000000;
 165 #endif
 166
 167 #ifdef DEBUG_MMAP
 168     {
 169         printf("mmap: start=0x%lx len=0x%lx prot=%c%c%c flags=",
 170                start, len,
 171                prot & PROT_READ ? 'r' : '-',
 172                prot & PROT_WRITE ? 'w' : '-',
 173                prot & PROT_EXEC ? 'x' : '-');
 174         if (flags & MAP_FIXED)
 175             printf("MAP_FIXED ");
 176         if (flags & MAP_ANONYMOUS)
 177             printf("MAP_ANON ");
 178         switch(flags & MAP_TYPE) {
 179         case MAP_PRIVATE:
 180             printf("MAP_PRIVATE ");
 181             break;
 182         case MAP_SHARED:
 183             printf("MAP_SHARED ");
 184             break;
 185         default:
 186             printf("[MAP_TYPE=0x%x] ", flags & MAP_TYPE);
 187             break;
 188         }
 189         printf("fd=%d offset=%lx\n", fd, offset);
 190     }
 191 #endif
 192
 193     if (offset & ~TARGET_PAGE_MASK) {
 194         errno = EINVAL;
 195         return -1;
 196     }
 197
 198     len = TARGET_PAGE_ALIGN(len);
 199     if (len == 0)
 200         return start;
 201     real_start = start & qemu_host_page_mask;
 202
 203     if (!(flags & MAP_FIXED)) {
 204 #if defined(__alpha__) || defined(__sparc__) || defined(__x86_64__) || \
 205     defined(__ia64) || defined(__mips__) || defined(__CYGWIN__)
 206         /* tell the kernel to search at the same place as i386 */
 207         if (real_start == 0) {
 208             real_start = last_start;
 209             last_start += HOST_PAGE_ALIGN(len);
 210         }
 211 #endif
 212         if (0 && qemu_host_page_size != qemu_real_host_page_size) {
 213             /* NOTE: this code is only for debugging with '-p' option */
 214             /* ??? Can also occur when TARGET_PAGE_SIZE > host page size.  */
 215             /* reserve a memory area */
 216             /* ??? This needs fixing for remapping.  */
 217 abort();
 218             host_len = HOST_PAGE_ALIGN(len) + qemu_host_page_size - TARGET_PAGE_SIZE;
 219             real_start = (long)mmap(g2h(real_start), host_len, PROT_NONE,
 220                                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 221             if (real_start == -1)
 222                 return real_start;
 223             real_end = real_start + host_len;
 224             start = HOST_PAGE_ALIGN(real_start);
 225             end = start + HOST_PAGE_ALIGN(len);
 226             if (start > real_start)
 227                 munmap((void *)real_start, start - real_start);
 228             if (end < real_end)
 229                 munmap((void *)end, real_end - end);
 230             /* use it as a fixed mapping */
 231             flags |= MAP_FIXED;
 232         } else {
 233             /* if not fixed, no need to do anything */
 234             host_offset = offset & qemu_host_page_mask;
 235             host_len = len + offset - host_offset;
 236             host_start = (long)mmap(real_start ? g2h(real_start) : NULL,
 237                                     host_len, prot, flags, fd, host_offset);
 238             if (host_start == -1)
 239                 return host_start;
 240             /* update start so that it points to the file position at 'offset' */
 241             if (!(flags & MAP_ANONYMOUS))
 242                 host_start += offset - host_offset;
 243             start = h2g(host_start);
 244             goto the_end1;
 245         }
 246     }
 247
 248     if (start & ~TARGET_PAGE_MASK) {
 249         errno = EINVAL;
 250         return -1;
 251     }
 252     end = start + len;
 253     real_end = HOST_PAGE_ALIGN(end);
 254
 255     /* worst case: we cannot map the file because the offset is not
 256        aligned, so we read it */
 257     if (!(flags & MAP_ANONYMOUS) &&
 258         (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) {
 259         /* msync() won't work here, so we return an error if write is
 260            possible while it is a shared mapping */
 261         if ((flags & MAP_TYPE) == MAP_SHARED &&
 262             (prot & PROT_WRITE)) {
 263             errno = EINVAL;
 264             return -1;
 265         }
 266         retaddr = target_mmap(start, len, prot | PROT_WRITE,
 267                               MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
 268                               -1, 0);
 269         if (retaddr == -1)
 270             return retaddr;
 271         pread(fd, g2h(start), len, offset);
 272         if (!(prot & PROT_WRITE)) {
 273             ret = target_mprotect(start, len, prot);
 274             if (ret != 0)
 275                 return ret;
 276         }
 277         goto the_end;
 278     }
 279
 280     /* handle the start of the mapping */
 281     if (start > real_start) {
 282         if (real_end == real_start + qemu_host_page_size) {
 283             /* one single host page */
 284             ret = mmap_frag(real_start, start, end,
 285                             prot, flags, fd, offset);
 286             if (ret == -1)
 287                 return ret;
 288             goto the_end1;
 289         }
 290         ret = mmap_frag(real_start, start, real_start + qemu_host_page_size,
 291                         prot, flags, fd, offset);
 292         if (ret == -1)
 293             return ret;
 294         real_start += qemu_host_page_size;
 295     }
 296     /* handle the end of the mapping */
 297     if (end < real_end) {
 298         ret = mmap_frag(real_end - qemu_host_page_size,
 299                         real_end - qemu_host_page_size, real_end,
 300                         prot, flags, fd,
 301                         offset + real_end - qemu_host_page_size - start);
 302         if (ret == -1)
 303             return ret;
 304         real_end -= qemu_host_page_size;
 305     }
 306
 307     /* map the middle (easier) */
 308     if (real_start < real_end) {
 309         unsigned long offset1;
 310         if (flags & MAP_ANONYMOUS)
 311           offset1 = 0;
 312         else
 313           offset1 = offset + real_start - start;
 314         ret = (long)mmap(g2h(real_start), real_end - real_start,
 315                          prot, flags, fd, offset1);
 316         if (ret == -1)
 317             return ret;
 318     }
 319  the_end1:
 320     page_set_flags(start, start + len, prot | PAGE_VALID);
 321  the_end:
 322 #ifdef DEBUG_MMAP
 323     printf("ret=0x%lx\n", (long)start);
 324     page_dump(stdout);
 325     printf("\n");
 326 #endif
 327     return start;
 328 }
 329
 330 int target_munmap(target_ulong start, target_ulong len)
 331 {
 332     target_ulong end, real_start, real_end, addr;
 333     int prot, ret;
 334
 335 #ifdef DEBUG_MMAP
 336     printf("munmap: start=0x%lx len=0x%lx\n", start, len);
 337 #endif
 338     if (start & ~TARGET_PAGE_MASK)
 339         return -EINVAL;
 340     len = TARGET_PAGE_ALIGN(len);
 341     if (len == 0)
 342         return -EINVAL;
 343     end = start + len;
 344     real_start = start & qemu_host_page_mask;
 345     real_end = HOST_PAGE_ALIGN(end);
 346
 347     if (start > real_start) {
 348         /* handle host page containing start */
 349         prot = 0;
 350         for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) {
 351             prot |= page_get_flags(addr);
 352         }
 353         if (real_end == real_start + qemu_host_page_size) {
 354             for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
 355                 prot |= page_get_flags(addr);
 356             }
 357             end = real_end;
 358         }
 359         if (prot != 0)
 360             real_start += qemu_host_page_size;
 361     }
 362     if (end < real_end) {
 363         prot = 0;
 364         for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
 365             prot |= page_get_flags(addr);
 366         }
 367         if (prot != 0)
 368             real_end -= qemu_host_page_size;
 369     }
 370
 371     /* unmap what we can */
 372     if (real_start < real_end) {
 373         ret = munmap((void *)real_start, real_end - real_start);
 374         if (ret != 0)
 375             return ret;
 376     }
 377
 378     page_set_flags(start, start + len, 0);
 379     return 0;
 380 }
 381
 382 /* XXX: currently, we only handle MAP_ANONYMOUS and not MAP_FIXED
 383    blocks which have been allocated starting on a host page */
 384 long target_mremap(target_ulong old_addr, target_ulong old_size,
 385                    target_ulong new_size, unsigned long flags,
 386                    target_ulong new_addr)
 387 {
 388     int prot;
 389
 390     /* XXX: use 5 args syscall */
 391     new_addr = (long)mremap(g2h(old_addr), old_size, new_size, flags);
 392     if (new_addr == -1)
 393         return new_addr;
 394     new_addr = h2g(new_addr);
 395     prot = page_get_flags(old_addr);
 396     page_set_flags(old_addr, old_addr + old_size, 0);
 397     page_set_flags(new_addr, new_addr + new_size, prot | PAGE_VALID);
 398     return new_addr;
 399 }
 400
 401 int target_msync(target_ulong start, target_ulong len, int flags)
 402 {
 403     target_ulong end;
 404
 405     if (start & ~TARGET_PAGE_MASK)
 406         return -EINVAL;
 407     len = TARGET_PAGE_ALIGN(len);
 408     end = start + len;
 409     if (end < start)
 410         return -EINVAL;
 411     if (end == start)
 412         return 0;
 413
 414     start &= qemu_host_page_mask;
 415     return msync(g2h(start), end - start, flags);
 416 }
 417