mono/utils/mono-mmap.c

   1 /*
   2  * mono-mmap.c: Support for mapping code into the process address space
   3  *
   4  * Author:
   5  *   Mono Team (mono-list@lists.ximian.com)
   6  *
   7  * Copyright 2001-2008 Novell, Inc.
   8  */
   9
  10 #include "config.h"
  11
  12 #ifdef HOST_WIN32
  13 #include <windows.h>
  14 #include <io.h>
  15 #else
  16 #include <sys/types.h>
  17 #if HAVE_SYS_STAT_H
  18 #include <sys/stat.h>
  19 #endif
  20 #if HAVE_SYS_MMAN_H
  21 #include <sys/mman.h>
  22 #endif
  23 #include <fcntl.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <stdlib.h>
  27 #include <signal.h>
  28 #include <errno.h>
  29 #endif
  30
  31 #include "mono-mmap.h"
  32 #include "mono-proclib.h"
  33
  34 #ifndef MAP_ANONYMOUS
  35 #define MAP_ANONYMOUS MAP_ANON
  36 #endif
  37
  38 #ifndef MAP_32BIT
  39 #define MAP_32BIT 0
  40 #endif
  41
  42 typedef struct {
  43         int size;
  44         int pid;
  45         int reserved;
  46         short stats_start;
  47         short stats_end;
  48 } SAreaHeader;
  49
  50 static void* malloced_shared_area = NULL;
  51
  52 static void*
  53 malloc_shared_area (int pid)
  54 {
  55         int size = mono_pagesize ();
  56         SAreaHeader *sarea = g_malloc0 (size);
  57         sarea->size = size;
  58         sarea->pid = pid;
  59         sarea->stats_start = sizeof (SAreaHeader);
  60         sarea->stats_end = sizeof (SAreaHeader);
  61
  62         return sarea;
  63 }
  64
  65 #ifdef HOST_WIN32
  66
  67 int
  68 mono_pagesize (void)
  69 {
  70         SYSTEM_INFO info;
  71         static int saved_pagesize = 0;
  72         if (saved_pagesize)
  73                 return saved_pagesize;
  74         GetSystemInfo (&info);
  75         saved_pagesize = info.dwAllocationGranularity;
  76         return saved_pagesize;
  77 }
  78
  79 static int
  80 prot_from_flags (int flags)
  81 {
  82         int prot = flags & (MONO_MMAP_READ|MONO_MMAP_WRITE|MONO_MMAP_EXEC);
  83         switch (prot) {
  84         case 0: prot = PAGE_NOACCESS; break;
  85         case MONO_MMAP_READ: prot = PAGE_READONLY; break;
  86         case MONO_MMAP_READ|MONO_MMAP_EXEC: prot = PAGE_EXECUTE_READ; break;
  87         case MONO_MMAP_READ|MONO_MMAP_WRITE: prot = PAGE_READWRITE; break;
  88         case MONO_MMAP_READ|MONO_MMAP_WRITE|MONO_MMAP_EXEC: prot = PAGE_EXECUTE_READWRITE; break;
  89         case MONO_MMAP_WRITE: prot = PAGE_READWRITE; break;
  90         case MONO_MMAP_WRITE|MONO_MMAP_EXEC: prot = PAGE_EXECUTE_READWRITE; break;
  91         case MONO_MMAP_EXEC: prot = PAGE_EXECUTE; break;
  92         default:
  93                 g_assert_not_reached ();
  94         }
  95         return prot;
  96 }
  97
  98 void*
  99 mono_valloc (void *addr, size_t length, int flags)
 100 {
 101         void *ptr;
 102         int mflags = MEM_COMMIT;
 103         int prot = prot_from_flags (flags);
 104         /* translate the flags */
 105
 106         ptr = VirtualAlloc (addr, length, mflags, prot);
 107         return ptr;
 108 }
 109
 110 int
 111 mono_vfree (void *addr, size_t length)
 112 {
 113         int res = VirtualFree (addr, 0, MEM_RELEASE);
 114
 115         g_assert (res);
 116
 117         return 0;
 118 }
 119
 120 void*
 121 mono_file_map (size_t length, int flags, int fd, guint64 offset, void **ret_handle)
 122 {
 123         void *ptr;
 124         int mflags = 0;
 125         HANDLE file, mapping;
 126         int prot = prot_from_flags (flags);
 127         /* translate the flags */
 128         /*if (flags & MONO_MMAP_PRIVATE)
 129                 mflags |= MAP_PRIVATE;
 130         if (flags & MONO_MMAP_SHARED)
 131                 mflags |= MAP_SHARED;
 132         if (flags & MONO_MMAP_ANON)
 133                 mflags |= MAP_ANONYMOUS;
 134         if (flags & MONO_MMAP_FIXED)
 135                 mflags |= MAP_FIXED;
 136         if (flags & MONO_MMAP_32BIT)
 137                 mflags |= MAP_32BIT;*/
 138
 139         mflags = FILE_MAP_READ;
 140         if (flags & MONO_MMAP_WRITE)
 141                 mflags = FILE_MAP_COPY;
 142
 143         file = (HANDLE) _get_osfhandle (fd);
 144         mapping = CreateFileMapping (file, NULL, prot, 0, 0, NULL);
 145         if (mapping == NULL)
 146                 return NULL;
 147         ptr = MapViewOfFile (mapping, mflags, 0, offset, length);
 148         if (ptr == NULL) {
 149                 CloseHandle (mapping);
 150                 return NULL;
 151         }
 152         *ret_handle = (void*)mapping;
 153         return ptr;
 154 }
 155
 156 int
 157 mono_file_unmap (void *addr, void *handle)
 158 {
 159         UnmapViewOfFile (addr);
 160         CloseHandle ((HANDLE)handle);
 161         return 0;
 162 }
 163
 164 int
 165 mono_mprotect (void *addr, size_t length, int flags)
 166 {
 167         DWORD oldprot;
 168         int prot = prot_from_flags (flags);
 169
 170         if (flags & MONO_MMAP_DISCARD) {
 171                 VirtualFree (addr, length, MEM_DECOMMIT);
 172                 VirtualAlloc (addr, length, MEM_COMMIT, prot);
 173                 return 0;
 174         }
 175         return VirtualProtect (addr, length, prot, &oldprot) == 0;
 176 }
 177
 178 void*
 179 mono_shared_area (void)
 180 {
 181         /* get the pid here */
 182         return malloc_shared_area (0);
 183 }
 184
 185 void
 186 mono_shared_area_remove (void)
 187 {
 188         if (malloced_shared_area)
 189                 g_free (malloced_shared_area);
 190 }
 191
 192 void*
 193 mono_shared_area_for_pid (void *pid)
 194 {
 195         return NULL;
 196 }
 197
 198 void
 199 mono_shared_area_unload (void *area)
 200 {
 201 }
 202
 203 int
 204 mono_shared_area_instances (void **array, int count)
 205 {
 206         return 0;
 207 }
 208
 209 #else
 210 #if defined(HAVE_MMAP)
 211
 212 /**
 213  * mono_pagesize:
 214  * Get the page size in use on the system. Addresses and sizes in the
 215  * mono_mmap(), mono_munmap() and mono_mprotect() calls must be pagesize
 216  * aligned.
 217  *
 218  * Returns: the page size in bytes.
 219  */
 220 int
 221 mono_pagesize (void)
 222 {
 223         static int saved_pagesize = 0;
 224         if (saved_pagesize)
 225                 return saved_pagesize;
 226         saved_pagesize = getpagesize ();
 227         return saved_pagesize;
 228 }
 229
 230 static int
 231 prot_from_flags (int flags)
 232 {
 233         int prot = PROT_NONE;
 234         /* translate the protection bits */
 235         if (flags & MONO_MMAP_READ)
 236                 prot |= PROT_READ;
 237         if (flags & MONO_MMAP_WRITE)
 238                 prot |= PROT_WRITE;
 239         if (flags & MONO_MMAP_EXEC)
 240                 prot |= PROT_EXEC;
 241         return prot;
 242 }
 243
 244 /**
 245  * mono_valloc:
 246  * @addr: memory address
 247  * @length: memory area size
 248  * @flags: protection flags
 249  *
 250  * Allocates @length bytes of virtual memory with the @flags
 251  * protection. @addr can be a preferred memory address or a
 252  * mandatory one if MONO_MMAP_FIXED is set in @flags.
 253  * @addr must be pagesize aligned and can be NULL.
 254  * @length must be a multiple of pagesize.
 255  *
 256  * Returns: NULL on failure, the address of the memory area otherwise
 257  */
 258 void*
 259 mono_valloc (void *addr, size_t length, int flags)
 260 {
 261         void *ptr;
 262         int mflags = 0;
 263         int prot = prot_from_flags (flags);
 264         /* translate the flags */
 265         if (flags & MONO_MMAP_FIXED)
 266                 mflags |= MAP_FIXED;
 267         if (flags & MONO_MMAP_32BIT)
 268                 mflags |= MAP_32BIT;
 269
 270         mflags |= MAP_ANONYMOUS;
 271         mflags |= MAP_PRIVATE;
 272
 273         ptr = mmap (addr, length, prot, mflags, -1, 0);
 274         if (ptr == (void*)-1) {
 275                 int fd = open ("/dev/zero", O_RDONLY);
 276                 if (fd != -1) {
 277                         ptr = mmap (addr, length, prot, mflags, fd, 0);
 278                         close (fd);
 279                 }
 280                 if (ptr == (void*)-1)
 281                         return NULL;
 282         }
 283         return ptr;
 284 }
 285
 286 /**
 287  * mono_vfree:
 288  * @addr: memory address returned by mono_valloc ()
 289  * @length: size of memory area
 290  *
 291  * Remove the memory mapping at the address @addr.
 292  *
 293  * Returns: 0 on success.
 294  */
 295 int
 296 mono_vfree (void *addr, size_t length)
 297 {
 298         return munmap (addr, length);
 299 }
 300
 301 /**
 302  * mono_file_map:
 303  * @length: size of data to map
 304  * @flags: protection flags
 305  * @fd: file descriptor
 306  * @offset: offset in the file
 307  * @ret_handle: pointer to storage for returning a handle for the map
 308  *
 309  * Map the area of the file pointed to by the file descriptor @fd, at offset
 310  * @offset and of size @length in memory according to the protection flags
 311  * @flags.
 312  * @offset and @length must be multiples of the page size.
 313  * @ret_handle must point to a void*: this value must be used when unmapping
 314  * the memory area using mono_file_unmap ().
 315  *
 316  */
 317 void*
 318 mono_file_map (size_t length, int flags, int fd, guint64 offset, void **ret_handle)
 319 {
 320         void *ptr;
 321         int mflags = 0;
 322         int prot = prot_from_flags (flags);
 323         /* translate the flags */
 324         if (flags & MONO_MMAP_PRIVATE)
 325                 mflags |= MAP_PRIVATE;
 326         if (flags & MONO_MMAP_SHARED)
 327                 mflags |= MAP_SHARED;
 328         if (flags & MONO_MMAP_FIXED)
 329                 mflags |= MAP_FIXED;
 330         if (flags & MONO_MMAP_32BIT)
 331                 mflags |= MAP_32BIT;
 332
 333         ptr = mmap (0, length, prot, mflags, fd, offset);
 334         if (ptr == (void*)-1)
 335                 return NULL;
 336         *ret_handle = (void*)length;
 337         return ptr;
 338 }
 339
 340 /**
 341  * mono_file_unmap:
 342  * @addr: memory address returned by mono_file_map ()
 343  * @handle: handle of memory map
 344  *
 345  * Remove the memory mapping at the address @addr.
 346  * @handle must be the value returned in ret_handle by mono_file_map ().
 347  *
 348  * Returns: 0 on success.
 349  */
 350 int
 351 mono_file_unmap (void *addr, void *handle)
 352 {
 353         return munmap (addr, (size_t)handle);
 354 }
 355
 356 /**
 357  * mono_mprotect:
 358  * @addr: memory address
 359  * @length: size of memory area
 360  * @flags: new protection flags
 361  *
 362  * Change the protection for the memory area at @addr for @length bytes
 363  * to matche the supplied @flags.
 364  * If @flags includes MON_MMAP_DISCARD the pages are discarded from memory
 365  * and the area is cleared to zero.
 366  * @addr must be aligned to the page size.
 367  * @length must be a multiple of the page size.
 368  *
 369  * Returns: 0 on success.
 370  */
 371 int
 372 mono_mprotect (void *addr, size_t length, int flags)
 373 {
 374         int prot = prot_from_flags (flags);
 375
 376         if (flags & MONO_MMAP_DISCARD) {
 377                 /* on non-linux the pages are not guaranteed to be zeroed (*bsd, osx at least) */
 378 #ifdef __linux__
 379                 if (madvise (addr, length, MADV_DONTNEED))
 380                         memset (addr, 0, length);
 381 #else
 382                 memset (addr, 0, length);
 383 #ifdef HAVE_MADVISE
 384                 madvise (addr, length, MADV_DONTNEED);
 385                 madvise (addr, length, MADV_FREE);
 386 #else
 387                 posix_madvise (addr, length, POSIX_MADV_DONTNEED);
 388 #endif
 389 #endif
 390         }
 391         return mprotect (addr, length, prot);
 392 }
 393
 394 #else
 395
 396 /* dummy malloc-based implementation */
 397 int
 398 mono_pagesize (void)
 399 {
 400         return 4096;
 401 }
 402
 403 void*
 404 mono_valloc (void *addr, size_t length, int flags)
 405 {
 406         return malloc (length);
 407 }
 408
 409 int
 410 mono_vfree (void *addr, size_t length)
 411 {
 412         free (addr);
 413         return 0;
 414 }
 415
 416 int
 417 mono_mprotect (void *addr, size_t length, int flags)
 418 {
 419         if (flags & MONO_MMAP_DISCARD) {
 420                 memset (addr, 0, length);
 421         }
 422         return 0;
 423 }
 424 #endif // HAVE_MMAP
 425
 426 #if defined(HAVE_SHM_OPEN)
 427
 428 static int
 429 mono_shared_area_instances_slow (void **array, int count, gboolean cleanup)
 430 {
 431         int i, j = 0;
 432         int num;
 433         void *data;
 434         gpointer *processes = mono_process_list (&num);
 435         for (i = 0; i < num; ++i) {
 436                 data = mono_shared_area_for_pid (processes [i]);
 437                 if (!data)
 438                         continue;
 439                 mono_shared_area_unload (data);
 440                 if (!cleanup) {
 441                         if (j < count)
 442                                 array [j++] = processes [i];
 443                         else
 444                                 break;
 445                 }
 446         }
 447         g_free (processes);
 448         return j;
 449 }
 450
 451 static int
 452 mono_shared_area_instances_helper (void **array, int count, gboolean cleanup)
 453 {
 454         const char *name;
 455         int i = 0;
 456         int curpid = getpid ();
 457         GDir *dir = g_dir_open ("/dev/shm/", 0, NULL);
 458         if (!dir)
 459                 return mono_shared_area_instances_slow (array, count, cleanup);
 460         while ((name = g_dir_read_name (dir))) {
 461                 int pid;
 462                 char *nend;
 463                 if (strncmp (name, "mono.", 5))
 464                         continue;
 465                 pid = strtol (name + 5, &nend, 10);
 466                 if (pid <= 0 || nend == name + 5 || *nend)
 467                         continue;
 468                 if (!cleanup) {
 469                         if (i < count)
 470                                 array [i++] = GINT_TO_POINTER (pid);
 471                         else
 472                                 break;
 473                 }
 474                 if (curpid != pid && kill (pid, 0) == -1 && (errno == ESRCH || errno == ENOMEM)) {
 475                         char buf [128];
 476                         g_snprintf (buf, sizeof (buf), "/mono.%d", pid);
 477                         shm_unlink (buf);
 478                 }
 479         }
 480         g_dir_close (dir);
 481         return i;
 482 }
 483
 484 void*
 485 mono_shared_area (void)
 486 {
 487         int fd;
 488         int pid = getpid ();
 489         /* we should allow the user to configure the size */
 490         int size = mono_pagesize ();
 491         char buf [128];
 492         void *res;
 493         SAreaHeader *header;
 494
 495         /* perform cleanup of segments left over from dead processes */
 496         mono_shared_area_instances_helper (NULL, 0, TRUE);
 497
 498         g_snprintf (buf, sizeof (buf), "/mono.%d", pid);
 499
 500         fd = shm_open (buf, O_CREAT|O_EXCL|O_RDWR, S_IRUSR|S_IWUSR|S_IRGRP);
 501         if (fd == -1 && errno == EEXIST) {
 502                 /* leftover */
 503                 shm_unlink (buf);
 504                 fd = shm_open (buf, O_CREAT|O_EXCL|O_RDWR, S_IRUSR|S_IWUSR|S_IRGRP);
 505         }
 506         /* in case of failure we try to return a memory area anyway,
 507          * even if it means the data can't be read by other processes
 508          */
 509         if (fd == -1)
 510                 return malloc_shared_area (pid);
 511         if (ftruncate (fd, size) != 0) {
 512                 shm_unlink (buf);
 513                 close (fd);
 514         }
 515         res = mmap (NULL, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 516         if (res == MAP_FAILED) {
 517                 shm_unlink (buf);
 518                 close (fd);
 519                 return malloc_shared_area (pid);
 520         }
 521         /* we don't need the file descriptor anymore */
 522         close (fd);
 523         header = res;
 524         header->size = size;
 525         header->pid = pid;
 526         header->stats_start = sizeof (SAreaHeader);
 527         header->stats_end = sizeof (SAreaHeader);
 528
 529         atexit (mono_shared_area_remove);
 530         return res;
 531 }
 532
 533 void
 534 mono_shared_area_remove (void)
 535 {
 536         char buf [128];
 537         g_snprintf (buf, sizeof (buf), "/mono.%d", getpid ());
 538         shm_unlink (buf);
 539         if (malloced_shared_area)
 540                 g_free (malloced_shared_area);
 541 }
 542
 543 void*
 544 mono_shared_area_for_pid (void *pid)
 545 {
 546         int fd;
 547         /* we should allow the user to configure the size */
 548         int size = mono_pagesize ();
 549         char buf [128];
 550         void *res;
 551
 552         g_snprintf (buf, sizeof (buf), "/mono.%d", GPOINTER_TO_INT (pid));
 553
 554         fd = shm_open (buf, O_RDONLY, S_IRUSR|S_IRGRP);
 555         if (fd == -1)
 556                 return NULL;
 557         res = mmap (NULL, size, PROT_READ, MAP_SHARED, fd, 0);
 558         if (res == MAP_FAILED) {
 559                 close (fd);
 560                 return NULL;
 561         }
 562         /* FIXME: validate the area */
 563         /* we don't need the file descriptor anymore */
 564         close (fd);
 565         return res;
 566 }
 567
 568 void
 569 mono_shared_area_unload  (void *area)
 570 {
 571         /* FIXME: currently we load only a page */
 572         munmap (area, mono_pagesize ());
 573 }
 574
 575 int
 576 mono_shared_area_instances (void **array, int count)
 577 {
 578         return mono_shared_area_instances_helper (array, count, FALSE);
 579 }
 580 #else
 581 void*
 582 mono_shared_area (void)
 583 {
 584         return malloc_shared_area (getpid ());
 585 }
 586
 587 void
 588 mono_shared_area_remove (void)
 589 {
 590         if (malloced_shared_area)
 591                 g_free (malloced_shared_area);
 592         malloced_shared_area = NULL;
 593 }
 594
 595 void*
 596 mono_shared_area_for_pid (void *pid)
 597 {
 598         return NULL;
 599 }
 600
 601 void
 602 mono_shared_area_unload (void *area)
 603 {
 604 }
 605
 606 int
 607 mono_shared_area_instances (void **array, int count)
 608 {
 609         return 0;
 610 }
 611
 612 #endif // HAVE_SHM_OPEN
 613
 614 #endif // HOST_WIN32