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 */
  33 int target_mprotect(unsigned long start, unsigned long len, int prot)
  34 {
  35     unsigned long 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 & 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 + 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((void *)host_start, host_page_size, prot1 & PAGE_BITS);
  71         if (ret != 0)
  72             return ret;
  73         host_start += 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((void *)(host_end - host_page_size), host_page_size,
  81                        prot1 & PAGE_BITS);
  82         if (ret != 0)
  83             return ret;
  84         host_end -= host_page_size;
  85     }
  86
  87     /* handle the pages in the middle */
  88     if (host_start < host_end) {
  89         ret = mprotect((void *)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 int mmap_frag(unsigned long host_start,
  99                unsigned long start, unsigned long end,
 100                int prot, int flags, int fd, unsigned long offset)
 101 {
 102     unsigned long host_end, ret, addr;
 103     int prot1, prot_new;
 104
 105     host_end = host_start + host_page_size;
 106
 107     /* get the protection of the target pages outside the mapping */
 108     prot1 = 0;
 109     for(addr = host_start; addr < host_end; addr++) {
 110         if (addr < start || addr >= end)
 111             prot1 |= page_get_flags(addr);
 112     }
 113
 114     if (prot1 == 0) {
 115         /* no page was there, so we allocate one */
 116         ret = (long)mmap((void *)host_start, host_page_size, prot,
 117                          flags | MAP_ANONYMOUS, -1, 0);
 118         if (ret == -1)
 119             return ret;
 120     }
 121     prot1 &= PAGE_BITS;
 122
 123     prot_new = prot | prot1;
 124     if (!(flags & MAP_ANONYMOUS)) {
 125         /* msync() won't work here, so we return an error if write is
 126            possible while it is a shared mapping */
 127         if ((flags & MAP_TYPE) == MAP_SHARED &&
 128             (prot & PROT_WRITE))
 129             return -EINVAL;
 130
 131         /* adjust protection to be able to read */
 132         if (!(prot1 & PROT_WRITE))
 133             mprotect((void *)host_start, host_page_size, prot1 | PROT_WRITE);
 134
 135         /* read the corresponding file data */
 136         pread(fd, (void *)start, end - start, offset);
 137
 138         /* put final protection */
 139         if (prot_new != (prot1 | PROT_WRITE))
 140             mprotect((void *)host_start, host_page_size, prot_new);
 141     } else {
 142         /* just update the protection */
 143         if (prot_new != prot1) {
 144             mprotect((void *)host_start, host_page_size, prot_new);
 145         }
 146     }
 147     return 0;
 148 }
 149
 150 /* NOTE: all the constants are the HOST ones */
 151 long target_mmap(unsigned long start, unsigned long len, int prot,
 152                  int flags, int fd, unsigned long offset)
 153 {
 154     unsigned long ret, end, host_start, host_end, retaddr, host_offset, host_len;
 155
 156 #ifdef DEBUG_MMAP
 157     {
 158         printf("mmap: start=0x%lx len=0x%lx prot=%c%c%c flags=",
 159                start, len,
 160                prot & PROT_READ ? 'r' : '-',
 161                prot & PROT_WRITE ? 'w' : '-',
 162                prot & PROT_EXEC ? 'x' : '-');
 163         if (flags & MAP_FIXED)
 164             printf("MAP_FIXED ");
 165         if (flags & MAP_ANONYMOUS)
 166             printf("MAP_ANON ");
 167         switch(flags & MAP_TYPE) {
 168         case MAP_PRIVATE:
 169             printf("MAP_PRIVATE ");
 170             break;
 171         case MAP_SHARED:
 172             printf("MAP_SHARED ");
 173             break;
 174         default:
 175             printf("[MAP_TYPE=0x%x] ", flags & MAP_TYPE);
 176             break;
 177         }
 178         printf("fd=%d offset=%lx\n", fd, offset);
 179     }
 180 #endif
 181
 182     if (offset & ~TARGET_PAGE_MASK)
 183         return -EINVAL;
 184
 185     len = TARGET_PAGE_ALIGN(len);
 186     if (len == 0)
 187         return start;
 188     host_start = start & host_page_mask;
 189
 190     if (!(flags & MAP_FIXED)) {
 191 #if defined(__alpha__) || defined(__sparc__)
 192         /* tell the kenel to search at the same place as i386 */
 193         if (host_start == 0)
 194             host_start = 0x40000000;
 195 #endif
 196         if (host_page_size != real_host_page_size) {
 197             /* NOTE: this code is only for debugging with '-p' option */
 198             /* reserve a memory area */
 199             host_len = HOST_PAGE_ALIGN(len) + host_page_size - TARGET_PAGE_SIZE;
 200             host_start = (long)mmap((void *)host_start, host_len, PROT_NONE,
 201                                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 202             if (host_start == -1)
 203                 return host_start;
 204             host_end = host_start + host_len;
 205             start = HOST_PAGE_ALIGN(host_start);
 206             end = start + HOST_PAGE_ALIGN(len);
 207             if (start > host_start)
 208                 munmap((void *)host_start, start - host_start);
 209             if (end < host_end)
 210                 munmap((void *)end, host_end - end);
 211             /* use it as a fixed mapping */
 212             flags |= MAP_FIXED;
 213         } else {
 214             /* if not fixed, no need to do anything */
 215             host_offset = offset & host_page_mask;
 216             host_len = len + offset - host_offset;
 217             start = (long)mmap((void *)host_start, host_len,
 218                                prot, flags, fd, host_offset);
 219             if (start == -1)
 220                 return start;
 221             /* update start so that it points to the file position at 'offset' */
 222             if (!(flags & MAP_ANONYMOUS))
 223                 start += offset - host_offset;
 224             goto the_end1;
 225         }
 226     }
 227
 228     if (start & ~TARGET_PAGE_MASK)
 229         return -EINVAL;
 230     end = start + len;
 231     host_end = HOST_PAGE_ALIGN(end);
 232
 233     /* worst case: we cannot map the file because the offset is not
 234        aligned, so we read it */
 235     if (!(flags & MAP_ANONYMOUS) &&
 236         (offset & ~host_page_mask) != (start & ~host_page_mask)) {
 237         /* msync() won't work here, so we return an error if write is
 238            possible while it is a shared mapping */
 239         if ((flags & MAP_TYPE) == MAP_SHARED &&
 240             (prot & PROT_WRITE))
 241             return -EINVAL;
 242         retaddr = target_mmap(start, len, prot | PROT_WRITE,
 243                               MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
 244                               -1, 0);
 245         if (retaddr == -1)
 246             return retaddr;
 247         pread(fd, (void *)start, len, offset);
 248         if (!(prot & PROT_WRITE)) {
 249             ret = target_mprotect(start, len, prot);
 250             if (ret != 0)
 251                 return ret;
 252         }
 253         goto the_end;
 254     }
 255
 256     /* handle the start of the mapping */
 257     if (start > host_start) {
 258         if (host_end == host_start + host_page_size) {
 259             /* one single host page */
 260             ret = mmap_frag(host_start, start, end,
 261                             prot, flags, fd, offset);
 262             if (ret == -1)
 263                 return ret;
 264             goto the_end1;
 265         }
 266         ret = mmap_frag(host_start, start, host_start + host_page_size,
 267                         prot, flags, fd, offset);
 268         if (ret == -1)
 269             return ret;
 270         host_start += host_page_size;
 271     }
 272     /* handle the end of the mapping */
 273     if (end < host_end) {
 274         ret = mmap_frag(host_end - host_page_size,
 275                         host_end - host_page_size, host_end,
 276                         prot, flags, fd,
 277                         offset + host_end - host_page_size - start);
 278         if (ret == -1)
 279             return ret;
 280         host_end -= host_page_size;
 281     }
 282
 283     /* map the middle (easier) */
 284     if (host_start < host_end) {
 285         unsigned long offset1;
 286         if (flags & MAP_ANONYMOUS)
 287           offset1 = 0;
 288         else
 289           offset1 = offset + host_start - start;
 290         ret = (long)mmap((void *)host_start, host_end - host_start,
 291                          prot, flags, fd, offset1);
 292         if (ret == -1)
 293             return ret;
 294     }
 295  the_end1:
 296     page_set_flags(start, start + len, prot | PAGE_VALID);
 297  the_end:
 298 #ifdef DEBUG_MMAP
 299     printf("ret=0x%lx\n", (long)start);
 300     page_dump(stdout);
 301     printf("\n");
 302 #endif
 303     return start;
 304 }
 305
 306 int target_munmap(unsigned long start, unsigned long len)
 307 {
 308     unsigned long end, host_start, host_end, addr;
 309     int prot, ret;
 310
 311 #ifdef DEBUG_MMAP
 312     printf("munmap: start=0x%lx len=0x%lx\n", start, len);
 313 #endif
 314     if (start & ~TARGET_PAGE_MASK)
 315         return -EINVAL;
 316     len = TARGET_PAGE_ALIGN(len);
 317     if (len == 0)
 318         return -EINVAL;
 319     end = start + len;
 320     host_start = start & host_page_mask;
 321     host_end = HOST_PAGE_ALIGN(end);
 322
 323     if (start > host_start) {
 324         /* handle host page containing start */
 325         prot = 0;
 326         for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
 327             prot |= page_get_flags(addr);
 328         }
 329         if (host_end == host_start + host_page_size) {
 330             for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
 331                 prot |= page_get_flags(addr);
 332             }
 333             end = host_end;
 334         }
 335         if (prot != 0)
 336             host_start += host_page_size;
 337     }
 338     if (end < host_end) {
 339         prot = 0;
 340         for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
 341             prot |= page_get_flags(addr);
 342         }
 343         if (prot != 0)
 344             host_end -= host_page_size;
 345     }
 346
 347     /* unmap what we can */
 348     if (host_start < host_end) {
 349         ret = munmap((void *)host_start, host_end - host_start);
 350         if (ret != 0)
 351             return ret;
 352     }
 353
 354     page_set_flags(start, start + len, 0);
 355     return 0;
 356 }
 357
 358 /* XXX: currently, we only handle MAP_ANONYMOUS and not MAP_FIXED
 359    blocks which have been allocated starting on a host page */
 360 long target_mremap(unsigned long old_addr, unsigned long old_size,
 361                    unsigned long new_size, unsigned long flags,
 362                    unsigned long new_addr)
 363 {
 364     int prot;
 365
 366     /* XXX: use 5 args syscall */
 367     new_addr = (long)mremap((void *)old_addr, old_size, new_size, flags);
 368     if (new_addr == -1)
 369         return new_addr;
 370     prot = page_get_flags(old_addr);
 371     page_set_flags(old_addr, old_addr + old_size, 0);
 372     page_set_flags(new_addr, new_addr + new_size, prot | PAGE_VALID);
 373     return new_addr;
 374 }
 375
 376 int target_msync(unsigned long start, unsigned long len, int flags)
 377 {
 378     unsigned long end;
 379
 380     if (start & ~TARGET_PAGE_MASK)
 381         return -EINVAL;
 382     len = TARGET_PAGE_ALIGN(len);
 383     end = start + len;
 384     if (end < start)
 385         return -EINVAL;
 386     if (end == start)
 387         return 0;
 388
 389     start &= host_page_mask;
 390     return msync((void *)start, end - start, flags);
 391 }
 392