1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/vmSymbols.hpp" 27 #include "memory/allocation.inline.hpp" 28 #include "memory/resourceArea.hpp" 29 #include "oops/oop.inline.hpp" 30 #include "os_linux.inline.hpp" 31 #include "runtime/handles.inline.hpp" 32 #include "runtime/perfMemory.hpp" 33 #include "services/memTracker.hpp" 34 #include "utilities/exceptions.hpp" 35 36 // put OS-includes here 37 # include <sys/types.h> 38 # include <sys/mman.h> 39 # include <errno.h> 40 # include <stdio.h> 41 # include <unistd.h> 42 # include <sys/stat.h> 43 # include <signal.h> 44 # include <pwd.h> 45 46 static char* backing_store_file_name = NULL; // name of the backing store 47 // file, if successfully created. 48 49 // Standard Memory Implementation Details 50 51 // create the PerfData memory region in standard memory. 52 // 53 static char* create_standard_memory(size_t size) { 54 55 // allocate an aligned chuck of memory 56 char* mapAddress = os::reserve_memory(size); 57 58 if (mapAddress == NULL) { 59 return NULL; 60 } 61 62 // commit memory 63 if (!os::commit_memory(mapAddress, size, !ExecMem)) { 64 if (PrintMiscellaneous && Verbose) { 65 warning("Could not commit PerfData memory\n"); 66 } 67 os::release_memory(mapAddress, size); 68 return NULL; 69 } 70 71 return mapAddress; 72 } 73 74 // delete the PerfData memory region 75 // 76 static void delete_standard_memory(char* addr, size_t size) { 77 78 // there are no persistent external resources to cleanup for standard 79 // memory. since DestroyJavaVM does not support unloading of the JVM, 80 // cleanup of the memory resource is not performed. The memory will be 81 // reclaimed by the OS upon termination of the process. 82 // 83 return; 84 } 85 86 // save the specified memory region to the given file 87 // 88 // Note: this function might be called from signal handler (by os::abort()), 89 // don't allocate heap memory. 90 // 91 static void save_memory_to_file(char* addr, size_t size) { 92 93 const char* destfile = PerfMemory::get_perfdata_file_path(); 94 assert(destfile[0] != '\0', "invalid PerfData file path"); 95 96 int result; 97 98 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 99 result);; 100 if (result == OS_ERR) { 101 if (PrintMiscellaneous && Verbose) { 102 warning("Could not create Perfdata save file: %s: %s\n", 103 destfile, strerror(errno)); 104 } 105 } else { 106 int fd = result; 107 108 for (size_t remaining = size; remaining > 0;) { 109 110 RESTARTABLE(::write(fd, addr, remaining), result); 111 if (result == OS_ERR) { 112 if (PrintMiscellaneous && Verbose) { 113 warning("Could not write Perfdata save file: %s: %s\n", 114 destfile, strerror(errno)); 115 } 116 break; 117 } 118 119 remaining -= (size_t)result; 120 addr += result; 121 } 122 123 result = ::close(fd); 124 if (PrintMiscellaneous && Verbose) { 125 if (result == OS_ERR) { 126 warning("Could not close %s: %s\n", destfile, strerror(errno)); 127 } 128 } 129 } 130 FREE_C_HEAP_ARRAY(char, destfile, mtInternal); 131 } 132 133 134 // Shared Memory Implementation Details 135 136 // Note: the solaris and linux shared memory implementation uses the mmap 137 // interface with a backing store file to implement named shared memory. 138 // Using the file system as the name space for shared memory allows a 139 // common name space to be supported across a variety of platforms. It 140 // also provides a name space that Java applications can deal with through 141 // simple file apis. 142 // 143 // The solaris and linux implementations store the backing store file in 144 // a user specific temporary directory located in the /tmp file system, 145 // which is always a local file system and is sometimes a RAM based file 146 // system. 147 148 // return the user specific temporary directory name. 149 // 150 // the caller is expected to free the allocated memory. 151 // 152 static char* get_user_tmp_dir(const char* user) { 153 154 const char* tmpdir = os::get_temp_directory(); 155 const char* perfdir = PERFDATA_NAME; 156 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 157 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 158 159 // construct the path name to user specific tmp directory 160 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 161 162 return dirname; 163 } 164 165 // convert the given file name into a process id. if the file 166 // does not meet the file naming constraints, return 0. 167 // 168 static pid_t filename_to_pid(const char* filename) { 169 170 // a filename that doesn't begin with a digit is not a 171 // candidate for conversion. 172 // 173 if (!isdigit(*filename)) { 174 return 0; 175 } 176 177 // check if file name can be converted to an integer without 178 // any leftover characters. 179 // 180 char* remainder = NULL; 181 errno = 0; 182 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 183 184 if (errno != 0) { 185 return 0; 186 } 187 188 // check for left over characters. If any, then the filename is 189 // not a candidate for conversion. 190 // 191 if (remainder != NULL && *remainder != '\0') { 192 return 0; 193 } 194 195 // successful conversion, return the pid 196 return pid; 197 } 198 199 200 // check if the given path is considered a secure directory for 201 // the backing store files. Returns true if the directory exists 202 // and is considered a secure location. Returns false if the path 203 // is a symbolic link or if an error occurred. 204 // 205 static bool is_directory_secure(const char* path) { 206 struct stat statbuf; 207 int result = 0; 208 209 RESTARTABLE(::lstat(path, &statbuf), result); 210 if (result == OS_ERR) { 211 return false; 212 } 213 214 // the path exists, now check it's mode 215 if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) { 216 // the path represents a link or some non-directory file type, 217 // which is not what we expected. declare it insecure. 218 // 219 return false; 220 } 221 else { 222 // we have an existing directory, check if the permissions are safe. 223 // 224 if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) { 225 // the directory is open for writing and could be subjected 226 // to a symlnk attack. declare it insecure. 227 // 228 return false; 229 } 230 } 231 return true; 232 } 233 234 235 // return the user name for the given user id 236 // 237 // the caller is expected to free the allocated memory. 238 // 239 static char* get_user_name(uid_t uid) { 240 241 struct passwd pwent; 242 243 // determine the max pwbuf size from sysconf, and hardcode 244 // a default if this not available through sysconf. 245 // 246 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 247 if (bufsize == -1) 248 bufsize = 1024; 249 250 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 251 252 // POSIX interface to getpwuid_r is used on LINUX 253 struct passwd* p; 254 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 255 256 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 257 if (PrintMiscellaneous && Verbose) { 258 if (result != 0) { 259 warning("Could not retrieve passwd entry: %s\n", 260 strerror(result)); 261 } 262 else if (p == NULL) { 263 // this check is added to protect against an observed problem 264 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0, 265 // indicating success, but has p == NULL. This was observed when 266 // inserting a file descriptor exhaustion fault prior to the call 267 // getpwuid_r() call. In this case, error is set to the appropriate 268 // error condition, but this is undocumented behavior. This check 269 // is safe under any condition, but the use of errno in the output 270 // message may result in an erroneous message. 271 // Bug Id 89052 was opened with RedHat. 272 // 273 warning("Could not retrieve passwd entry: %s\n", 274 strerror(errno)); 275 } 276 else { 277 warning("Could not determine user name: %s\n", 278 p->pw_name == NULL ? "pw_name = NULL" : 279 "pw_name zero length"); 280 } 281 } 282 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); 283 return NULL; 284 } 285 286 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 287 strcpy(user_name, p->pw_name); 288 289 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); 290 return user_name; 291 } 292 293 // return the name of the user that owns the process identified by vmid. 294 // 295 // This method uses a slow directory search algorithm to find the backing 296 // store file for the specified vmid and returns the user name, as determined 297 // by the user name suffix of the hsperfdata_<username> directory name. 298 // 299 // the caller is expected to free the allocated memory. 300 // 301 static char* get_user_name_slow(int vmid, TRAPS) { 302 303 // short circuit the directory search if the process doesn't even exist. 304 if (kill(vmid, 0) == OS_ERR) { 305 if (errno == ESRCH) { 306 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 307 "Process not found"); 308 } 309 else /* EPERM */ { 310 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 311 } 312 } 313 314 // directory search 315 char* oldest_user = NULL; 316 time_t oldest_ctime = 0; 317 318 const char* tmpdirname = os::get_temp_directory(); 319 320 DIR* tmpdirp = os::opendir(tmpdirname); 321 322 if (tmpdirp == NULL) { 323 return NULL; 324 } 325 326 // for each entry in the directory that matches the pattern hsperfdata_*, 327 // open the directory and check if the file for the given vmid exists. 328 // The file with the expected name and the latest creation date is used 329 // to determine the user name for the process id. 330 // 331 struct dirent* dentry; 332 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); 333 errno = 0; 334 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 335 336 // check if the directory entry is a hsperfdata file 337 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 338 continue; 339 } 340 341 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 342 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 343 strcpy(usrdir_name, tmpdirname); 344 strcat(usrdir_name, "/"); 345 strcat(usrdir_name, dentry->d_name); 346 347 DIR* subdirp = os::opendir(usrdir_name); 348 349 if (subdirp == NULL) { 350 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 351 continue; 352 } 353 354 // Since we don't create the backing store files in directories 355 // pointed to by symbolic links, we also don't follow them when 356 // looking for the files. We check for a symbolic link after the 357 // call to opendir in order to eliminate a small window where the 358 // symlink can be exploited. 359 // 360 if (!is_directory_secure(usrdir_name)) { 361 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 362 os::closedir(subdirp); 363 continue; 364 } 365 366 struct dirent* udentry; 367 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); 368 errno = 0; 369 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 370 371 if (filename_to_pid(udentry->d_name) == vmid) { 372 struct stat statbuf; 373 int result; 374 375 char* filename = NEW_C_HEAP_ARRAY(char, 376 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 377 378 strcpy(filename, usrdir_name); 379 strcat(filename, "/"); 380 strcat(filename, udentry->d_name); 381 382 // don't follow symbolic links for the file 383 RESTARTABLE(::lstat(filename, &statbuf), result); 384 if (result == OS_ERR) { 385 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 386 continue; 387 } 388 389 // skip over files that are not regular files. 390 if (!S_ISREG(statbuf.st_mode)) { 391 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 392 continue; 393 } 394 395 // compare and save filename with latest creation time 396 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 397 398 if (statbuf.st_ctime > oldest_ctime) { 399 char* user = strchr(dentry->d_name, '_') + 1; 400 401 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user, mtInternal); 402 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 403 404 strcpy(oldest_user, user); 405 oldest_ctime = statbuf.st_ctime; 406 } 407 } 408 409 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 410 } 411 } 412 os::closedir(subdirp); 413 FREE_C_HEAP_ARRAY(char, udbuf, mtInternal); 414 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 415 } 416 os::closedir(tmpdirp); 417 FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal); 418 419 return(oldest_user); 420 } 421 422 // return the name of the user that owns the JVM indicated by the given vmid. 423 // 424 static char* get_user_name(int vmid, TRAPS) { 425 return get_user_name_slow(vmid, CHECK_NULL); 426 } 427 428 // return the file name of the backing store file for the named 429 // shared memory region for the given user name and vmid. 430 // 431 // the caller is expected to free the allocated memory. 432 // 433 static char* get_sharedmem_filename(const char* dirname, int vmid) { 434 435 // add 2 for the file separator and a null terminator. 436 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 437 438 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 439 snprintf(name, nbytes, "%s/%d", dirname, vmid); 440 441 return name; 442 } 443 444 445 // remove file 446 // 447 // this method removes the file specified by the given path 448 // 449 static void remove_file(const char* path) { 450 451 int result; 452 453 // if the file is a directory, the following unlink will fail. since 454 // we don't expect to find directories in the user temp directory, we 455 // won't try to handle this situation. even if accidentially or 456 // maliciously planted, the directory's presence won't hurt anything. 457 // 458 RESTARTABLE(::unlink(path), result); 459 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 460 if (errno != ENOENT) { 461 warning("Could not unlink shared memory backing" 462 " store file %s : %s\n", path, strerror(errno)); 463 } 464 } 465 } 466 467 468 // remove file 469 // 470 // this method removes the file with the given file name in the 471 // named directory. 472 // 473 static void remove_file(const char* dirname, const char* filename) { 474 475 size_t nbytes = strlen(dirname) + strlen(filename) + 2; 476 char* path = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 477 478 strcpy(path, dirname); 479 strcat(path, "/"); 480 strcat(path, filename); 481 482 remove_file(path); 483 484 FREE_C_HEAP_ARRAY(char, path, mtInternal); 485 } 486 487 488 // cleanup stale shared memory resources 489 // 490 // This method attempts to remove all stale shared memory files in 491 // the named user temporary directory. It scans the named directory 492 // for files matching the pattern ^$[0-9]*$. For each file found, the 493 // process id is extracted from the file name and a test is run to 494 // determine if the process is alive. If the process is not alive, 495 // any stale file resources are removed. 496 // 497 static void cleanup_sharedmem_resources(const char* dirname) { 498 499 // open the user temp directory 500 DIR* dirp = os::opendir(dirname); 501 502 if (dirp == NULL) { 503 // directory doesn't exist, so there is nothing to cleanup 504 return; 505 } 506 507 if (!is_directory_secure(dirname)) { 508 // the directory is not a secure directory 509 return; 510 } 511 512 // for each entry in the directory that matches the expected file 513 // name pattern, determine if the file resources are stale and if 514 // so, remove the file resources. Note, instrumented HotSpot processes 515 // for this user may start and/or terminate during this search and 516 // remove or create new files in this directory. The behavior of this 517 // loop under these conditions is dependent upon the implementation of 518 // opendir/readdir. 519 // 520 struct dirent* entry; 521 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); 522 errno = 0; 523 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 524 525 pid_t pid = filename_to_pid(entry->d_name); 526 527 if (pid == 0) { 528 529 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 530 531 // attempt to remove all unexpected files, except "." and ".." 532 remove_file(dirname, entry->d_name); 533 } 534 535 errno = 0; 536 continue; 537 } 538 539 // we now have a file name that converts to a valid integer 540 // that could represent a process id . if this process id 541 // matches the current process id or the process is not running, 542 // then remove the stale file resources. 543 // 544 // process liveness is detected by sending signal number 0 to 545 // the process id (see kill(2)). if kill determines that the 546 // process does not exist, then the file resources are removed. 547 // if kill determines that that we don't have permission to 548 // signal the process, then the file resources are assumed to 549 // be stale and are removed because the resources for such a 550 // process should be in a different user specific directory. 551 // 552 if ((pid == os::current_process_id()) || 553 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 554 555 remove_file(dirname, entry->d_name); 556 } 557 errno = 0; 558 } 559 os::closedir(dirp); 560 FREE_C_HEAP_ARRAY(char, dbuf, mtInternal); 561 } 562 563 // make the user specific temporary directory. Returns true if 564 // the directory exists and is secure upon return. Returns false 565 // if the directory exists but is either a symlink, is otherwise 566 // insecure, or if an error occurred. 567 // 568 static bool make_user_tmp_dir(const char* dirname) { 569 570 // create the directory with 0755 permissions. note that the directory 571 // will be owned by euid::egid, which may not be the same as uid::gid. 572 // 573 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 574 if (errno == EEXIST) { 575 // The directory already exists and was probably created by another 576 // JVM instance. However, this could also be the result of a 577 // deliberate symlink. Verify that the existing directory is safe. 578 // 579 if (!is_directory_secure(dirname)) { 580 // directory is not secure 581 if (PrintMiscellaneous && Verbose) { 582 warning("%s directory is insecure\n", dirname); 583 } 584 return false; 585 } 586 } 587 else { 588 // we encountered some other failure while attempting 589 // to create the directory 590 // 591 if (PrintMiscellaneous && Verbose) { 592 warning("could not create directory %s: %s\n", 593 dirname, strerror(errno)); 594 } 595 return false; 596 } 597 } 598 return true; 599 } 600 601 // create the shared memory file resources 602 // 603 // This method creates the shared memory file with the given size 604 // This method also creates the user specific temporary directory, if 605 // it does not yet exist. 606 // 607 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 608 609 // make the user temporary directory 610 if (!make_user_tmp_dir(dirname)) { 611 // could not make/find the directory or the found directory 612 // was not secure 613 return -1; 614 } 615 616 int result; 617 618 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result); 619 if (result == OS_ERR) { 620 if (PrintMiscellaneous && Verbose) { 621 warning("could not create file %s: %s\n", filename, strerror(errno)); 622 } 623 return -1; 624 } 625 626 // save the file descriptor 627 int fd = result; 628 629 // set the file size 630 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 631 if (result == OS_ERR) { 632 if (PrintMiscellaneous && Verbose) { 633 warning("could not set shared memory file size: %s\n", strerror(errno)); 634 } 635 ::close(fd); 636 return -1; 637 } 638 639 // Verify that we have enough disk space for this file. 640 // We'll get random SIGBUS crashes on memory accesses if 641 // we don't. 642 643 for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) { 644 int zero_int = 0; 645 result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos)); 646 if (result == -1 ) break; 647 RESTARTABLE(::write(fd, &zero_int, 1), result); 648 if (result != 1) { 649 if (errno == ENOSPC) { 650 warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename); 651 } 652 break; 653 } 654 } 655 656 if (result != -1) { 657 return fd; 658 } else { 659 ::close(fd); 660 return -1; 661 } 662 } 663 664 // open the shared memory file for the given user and vmid. returns 665 // the file descriptor for the open file or -1 if the file could not 666 // be opened. 667 // 668 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 669 670 // open the file 671 int result; 672 RESTARTABLE(::open(filename, oflags), result); 673 if (result == OS_ERR) { 674 if (errno == ENOENT) { 675 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 676 "Process not found", OS_ERR); 677 } 678 else if (errno == EACCES) { 679 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 680 "Permission denied", OS_ERR); 681 } 682 else { 683 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR); 684 } 685 } 686 687 return result; 688 } 689 690 // create a named shared memory region. returns the address of the 691 // memory region on success or NULL on failure. A return value of 692 // NULL will ultimately disable the shared memory feature. 693 // 694 // On Solaris and Linux, the name space for shared memory objects 695 // is the file system name space. 696 // 697 // A monitoring application attaching to a JVM does not need to know 698 // the file system name of the shared memory object. However, it may 699 // be convenient for applications to discover the existence of newly 700 // created and terminating JVMs by watching the file system name space 701 // for files being created or removed. 702 // 703 static char* mmap_create_shared(size_t size) { 704 705 int result; 706 int fd; 707 char* mapAddress; 708 709 int vmid = os::current_process_id(); 710 711 char* user_name = get_user_name(geteuid()); 712 713 if (user_name == NULL) 714 return NULL; 715 716 char* dirname = get_user_tmp_dir(user_name); 717 char* filename = get_sharedmem_filename(dirname, vmid); 718 719 // cleanup any stale shared memory files 720 cleanup_sharedmem_resources(dirname); 721 722 assert(((size > 0) && (size % os::vm_page_size() == 0)), 723 "unexpected PerfMemory region size"); 724 725 fd = create_sharedmem_resources(dirname, filename, size); 726 727 FREE_C_HEAP_ARRAY(char, user_name, mtInternal); 728 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 729 730 if (fd == -1) { 731 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 732 return NULL; 733 } 734 735 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 736 737 result = ::close(fd); 738 assert(result != OS_ERR, "could not close file"); 739 740 if (mapAddress == MAP_FAILED) { 741 if (PrintMiscellaneous && Verbose) { 742 warning("mmap failed - %s\n", strerror(errno)); 743 } 744 remove_file(filename); 745 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 746 return NULL; 747 } 748 749 // save the file name for use in delete_shared_memory() 750 backing_store_file_name = filename; 751 752 // clear the shared memory region 753 (void)::memset((void*) mapAddress, 0, size); 754 755 // it does not go through os api, the operation has to record from here 756 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, mtInternal, CURRENT_PC); 757 758 return mapAddress; 759 } 760 761 // release a named shared memory region 762 // 763 static void unmap_shared(char* addr, size_t bytes) { 764 os::release_memory(addr, bytes); 765 } 766 767 // create the PerfData memory region in shared memory. 768 // 769 static char* create_shared_memory(size_t size) { 770 771 // create the shared memory region. 772 return mmap_create_shared(size); 773 } 774 775 // delete the shared PerfData memory region 776 // 777 static void delete_shared_memory(char* addr, size_t size) { 778 779 // cleanup the persistent shared memory resources. since DestroyJavaVM does 780 // not support unloading of the JVM, unmapping of the memory resource is 781 // not performed. The memory will be reclaimed by the OS upon termination of 782 // the process. The backing store file is deleted from the file system. 783 784 assert(!PerfDisableSharedMem, "shouldn't be here"); 785 786 if (backing_store_file_name != NULL) { 787 remove_file(backing_store_file_name); 788 // Don't.. Free heap memory could deadlock os::abort() if it is called 789 // from signal handler. OS will reclaim the heap memory. 790 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 791 backing_store_file_name = NULL; 792 } 793 } 794 795 // return the size of the file for the given file descriptor 796 // or 0 if it is not a valid size for a shared memory file 797 // 798 static size_t sharedmem_filesize(int fd, TRAPS) { 799 800 struct stat statbuf; 801 int result; 802 803 RESTARTABLE(::fstat(fd, &statbuf), result); 804 if (result == OS_ERR) { 805 if (PrintMiscellaneous && Verbose) { 806 warning("fstat failed: %s\n", strerror(errno)); 807 } 808 THROW_MSG_0(vmSymbols::java_io_IOException(), 809 "Could not determine PerfMemory size"); 810 } 811 812 if ((statbuf.st_size == 0) || 813 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 814 THROW_MSG_0(vmSymbols::java_lang_Exception(), 815 "Invalid PerfMemory size"); 816 } 817 818 return (size_t)statbuf.st_size; 819 } 820 821 // attach to a named shared memory region. 822 // 823 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 824 825 char* mapAddress; 826 int result; 827 int fd; 828 size_t size = 0; 829 const char* luser = NULL; 830 831 int mmap_prot; 832 int file_flags; 833 834 ResourceMark rm; 835 836 // map the high level access mode to the appropriate permission 837 // constructs for the file and the shared memory mapping. 838 if (mode == PerfMemory::PERF_MODE_RO) { 839 mmap_prot = PROT_READ; 840 file_flags = O_RDONLY; 841 } 842 else if (mode == PerfMemory::PERF_MODE_RW) { 843 #ifdef LATER 844 mmap_prot = PROT_READ | PROT_WRITE; 845 file_flags = O_RDWR; 846 #else 847 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 848 "Unsupported access mode"); 849 #endif 850 } 851 else { 852 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 853 "Illegal access mode"); 854 } 855 856 if (user == NULL || strlen(user) == 0) { 857 luser = get_user_name(vmid, CHECK); 858 } 859 else { 860 luser = user; 861 } 862 863 if (luser == NULL) { 864 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 865 "Could not map vmid to user Name"); 866 } 867 868 char* dirname = get_user_tmp_dir(luser); 869 870 // since we don't follow symbolic links when creating the backing 871 // store file, we don't follow them when attaching either. 872 // 873 if (!is_directory_secure(dirname)) { 874 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 875 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 876 "Process not found"); 877 } 878 879 char* filename = get_sharedmem_filename(dirname, vmid); 880 881 // copy heap memory to resource memory. the open_sharedmem_file 882 // method below need to use the filename, but could throw an 883 // exception. using a resource array prevents the leak that 884 // would otherwise occur. 885 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 886 strcpy(rfilename, filename); 887 888 // free the c heap resources that are no longer needed 889 if (luser != user) FREE_C_HEAP_ARRAY(char, luser, mtInternal); 890 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 891 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 892 893 // open the shared memory file for the give vmid 894 fd = open_sharedmem_file(rfilename, file_flags, THREAD); 895 896 if (fd == OS_ERR) { 897 return; 898 } 899 900 if (HAS_PENDING_EXCEPTION) { 901 ::close(fd); 902 return; 903 } 904 905 if (*sizep == 0) { 906 size = sharedmem_filesize(fd, CHECK); 907 } else { 908 size = *sizep; 909 } 910 911 assert(size > 0, "unexpected size <= 0"); 912 913 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 914 915 result = ::close(fd); 916 assert(result != OS_ERR, "could not close file"); 917 918 if (mapAddress == MAP_FAILED) { 919 if (PrintMiscellaneous && Verbose) { 920 warning("mmap failed: %s\n", strerror(errno)); 921 } 922 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 923 "Could not map PerfMemory"); 924 } 925 926 // it does not go through os api, the operation has to record from here 927 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, mtInternal, CURRENT_PC); 928 929 *addr = mapAddress; 930 *sizep = size; 931 932 if (PerfTraceMemOps) { 933 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 934 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress); 935 } 936 } 937 938 939 940 941 // create the PerfData memory region 942 // 943 // This method creates the memory region used to store performance 944 // data for the JVM. The memory may be created in standard or 945 // shared memory. 946 // 947 void PerfMemory::create_memory_region(size_t size) { 948 949 if (PerfDisableSharedMem) { 950 // do not share the memory for the performance data. 951 _start = create_standard_memory(size); 952 } 953 else { 954 _start = create_shared_memory(size); 955 if (_start == NULL) { 956 957 // creation of the shared memory region failed, attempt 958 // to create a contiguous, non-shared memory region instead. 959 // 960 if (PrintMiscellaneous && Verbose) { 961 warning("Reverting to non-shared PerfMemory region.\n"); 962 } 963 PerfDisableSharedMem = true; 964 _start = create_standard_memory(size); 965 } 966 } 967 968 if (_start != NULL) _capacity = size; 969 970 } 971 972 // delete the PerfData memory region 973 // 974 // This method deletes the memory region used to store performance 975 // data for the JVM. The memory region indicated by the <address, size> 976 // tuple will be inaccessible after a call to this method. 977 // 978 void PerfMemory::delete_memory_region() { 979 980 assert((start() != NULL && capacity() > 0), "verify proper state"); 981 982 // If user specifies PerfDataSaveFile, it will save the performance data 983 // to the specified file name no matter whether PerfDataSaveToFile is specified 984 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 985 // -XX:+PerfDataSaveToFile. 986 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 987 save_memory_to_file(start(), capacity()); 988 } 989 990 if (PerfDisableSharedMem) { 991 delete_standard_memory(start(), capacity()); 992 } 993 else { 994 delete_shared_memory(start(), capacity()); 995 } 996 } 997 998 // attach to the PerfData memory region for another JVM 999 // 1000 // This method returns an <address, size> tuple that points to 1001 // a memory buffer that is kept reasonably synchronized with 1002 // the PerfData memory region for the indicated JVM. This 1003 // buffer may be kept in synchronization via shared memory 1004 // or some other mechanism that keeps the buffer updated. 1005 // 1006 // If the JVM chooses not to support the attachability feature, 1007 // this method should throw an UnsupportedOperation exception. 1008 // 1009 // This implementation utilizes named shared memory to map 1010 // the indicated process's PerfData memory region into this JVMs 1011 // address space. 1012 // 1013 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1014 1015 if (vmid == 0 || vmid == os::current_process_id()) { 1016 *addrp = start(); 1017 *sizep = capacity(); 1018 return; 1019 } 1020 1021 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1022 } 1023 1024 // detach from the PerfData memory region of another JVM 1025 // 1026 // This method detaches the PerfData memory region of another 1027 // JVM, specified as an <address, size> tuple of a buffer 1028 // in this process's address space. This method may perform 1029 // arbitrary actions to accomplish the detachment. The memory 1030 // region specified by <address, size> will be inaccessible after 1031 // a call to this method. 1032 // 1033 // If the JVM chooses not to support the attachability feature, 1034 // this method should throw an UnsupportedOperation exception. 1035 // 1036 // This implementation utilizes named shared memory to detach 1037 // the indicated process's PerfData memory region from this 1038 // process's address space. 1039 // 1040 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1041 1042 assert(addr != 0, "address sanity check"); 1043 assert(bytes > 0, "capacity sanity check"); 1044 1045 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1046 // prevent accidental detachment of this process's PerfMemory region 1047 return; 1048 } 1049 1050 unmap_shared(addr, bytes); 1051 } 1052 1053 char* PerfMemory::backing_store_filename() { 1054 return backing_store_file_name; 1055 }