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_solaris.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 # include <procfs.h> 46 47 48 static char* backing_store_file_name = NULL; // name of the backing store 49 // file, if successfully created. 50 51 // Standard Memory Implementation Details 52 53 // create the PerfData memory region in standard memory. 54 // 55 static char* create_standard_memory(size_t size) { 56 57 // allocate an aligned chuck of memory 58 char* mapAddress = os::reserve_memory(size); 59 60 if (mapAddress == NULL) { 61 return NULL; 62 } 63 64 // commit memory 65 if (!os::commit_memory(mapAddress, size, !ExecMem)) { 66 if (PrintMiscellaneous && Verbose) { 67 warning("Could not commit PerfData memory\n"); 68 } 69 os::release_memory(mapAddress, size); 70 return NULL; 71 } 72 73 return mapAddress; 74 } 75 76 // delete the PerfData memory region 77 // 78 static void delete_standard_memory(char* addr, size_t size) { 79 80 // there are no persistent external resources to cleanup for standard 81 // memory. since DestroyJavaVM does not support unloading of the JVM, 82 // cleanup of the memory resource is not performed. The memory will be 83 // reclaimed by the OS upon termination of the process. 84 // 85 return; 86 } 87 88 // save the specified memory region to the given file 89 // 90 // Note: this function might be called from signal handler (by os::abort()), 91 // don't allocate heap memory. 92 // 93 static void save_memory_to_file(char* addr, size_t size) { 94 95 const char* destfile = PerfMemory::get_perfdata_file_path(); 96 assert(destfile[0] != '\0', "invalid PerfData file path"); 97 98 int result; 99 100 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 101 result);; 102 if (result == OS_ERR) { 103 if (PrintMiscellaneous && Verbose) { 104 warning("Could not create Perfdata save file: %s: %s\n", 105 destfile, strerror(errno)); 106 } 107 } else { 108 109 int fd = result; 110 111 for (size_t remaining = size; remaining > 0;) { 112 113 RESTARTABLE(::write(fd, addr, remaining), result); 114 if (result == OS_ERR) { 115 if (PrintMiscellaneous && Verbose) { 116 warning("Could not write Perfdata save file: %s: %s\n", 117 destfile, strerror(errno)); 118 } 119 break; 120 } 121 remaining -= (size_t)result; 122 addr += result; 123 } 124 125 result = ::close(fd); 126 if (PrintMiscellaneous && Verbose) { 127 if (result == OS_ERR) { 128 warning("Could not close %s: %s\n", destfile, strerror(errno)); 129 } 130 } 131 } 132 FREE_C_HEAP_ARRAY(char, destfile, mtInternal); 133 } 134 135 136 // Shared Memory Implementation Details 137 138 // Note: the solaris and linux shared memory implementation uses the mmap 139 // interface with a backing store file to implement named shared memory. 140 // Using the file system as the name space for shared memory allows a 141 // common name space to be supported across a variety of platforms. It 142 // also provides a name space that Java applications can deal with through 143 // simple file apis. 144 // 145 // The solaris and linux implementations store the backing store file in 146 // a user specific temporary directory located in the /tmp file system, 147 // which is always a local file system and is sometimes a RAM based file 148 // system. 149 150 // return the user specific temporary directory name. 151 // 152 // the caller is expected to free the allocated memory. 153 // 154 static char* get_user_tmp_dir(const char* user) { 155 156 const char* tmpdir = os::get_temp_directory(); 157 const char* perfdir = PERFDATA_NAME; 158 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 159 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 160 161 // construct the path name to user specific tmp directory 162 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 163 164 return dirname; 165 } 166 167 // convert the given file name into a process id. if the file 168 // does not meet the file naming constraints, return 0. 169 // 170 static pid_t filename_to_pid(const char* filename) { 171 172 // a filename that doesn't begin with a digit is not a 173 // candidate for conversion. 174 // 175 if (!isdigit(*filename)) { 176 return 0; 177 } 178 179 // check if file name can be converted to an integer without 180 // any leftover characters. 181 // 182 char* remainder = NULL; 183 errno = 0; 184 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 185 186 if (errno != 0) { 187 return 0; 188 } 189 190 // check for left over characters. If any, then the filename is 191 // not a candidate for conversion. 192 // 193 if (remainder != NULL && *remainder != '\0') { 194 return 0; 195 } 196 197 // successful conversion, return the pid 198 return pid; 199 } 200 201 202 // check if the given path is considered a secure directory for 203 // the backing store files. Returns true if the directory exists 204 // and is considered a secure location. Returns false if the path 205 // is a symbolic link or if an error occurred. 206 // 207 static bool is_directory_secure(const char* path) { 208 struct stat statbuf; 209 int result = 0; 210 211 RESTARTABLE(::lstat(path, &statbuf), result); 212 if (result == OS_ERR) { 213 return false; 214 } 215 216 // the path exists, now check it's mode 217 if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) { 218 // the path represents a link or some non-directory file type, 219 // which is not what we expected. declare it insecure. 220 // 221 return false; 222 } 223 else { 224 // we have an existing directory, check if the permissions are safe. 225 // 226 if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) { 227 // the directory is open for writing and could be subjected 228 // to a symlnk attack. declare it insecure. 229 // 230 return false; 231 } 232 } 233 return true; 234 } 235 236 237 // return the user name for the given user id 238 // 239 // the caller is expected to free the allocated memory. 240 // 241 static char* get_user_name(uid_t uid) { 242 243 struct passwd pwent; 244 245 // determine the max pwbuf size from sysconf, and hardcode 246 // a default if this not available through sysconf. 247 // 248 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 249 if (bufsize == -1) 250 bufsize = 1024; 251 252 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 253 254 #ifdef _GNU_SOURCE 255 struct passwd* p = NULL; 256 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 257 #else // _GNU_SOURCE 258 struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize); 259 #endif // _GNU_SOURCE 260 261 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 262 if (PrintMiscellaneous && Verbose) { 263 if (p == NULL) { 264 warning("Could not retrieve passwd entry: %s\n", 265 strerror(errno)); 266 } 267 else { 268 warning("Could not determine user name: %s\n", 269 p->pw_name == NULL ? "pw_name = NULL" : 270 "pw_name zero length"); 271 } 272 } 273 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); 274 return NULL; 275 } 276 277 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 278 strcpy(user_name, p->pw_name); 279 280 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); 281 return user_name; 282 } 283 284 // return the name of the user that owns the process identified by vmid. 285 // 286 // This method uses a slow directory search algorithm to find the backing 287 // store file for the specified vmid and returns the user name, as determined 288 // by the user name suffix of the hsperfdata_<username> directory name. 289 // 290 // the caller is expected to free the allocated memory. 291 // 292 static char* get_user_name_slow(int vmid, TRAPS) { 293 294 // short circuit the directory search if the process doesn't even exist. 295 if (kill(vmid, 0) == OS_ERR) { 296 if (errno == ESRCH) { 297 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 298 "Process not found"); 299 } 300 else /* EPERM */ { 301 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 302 } 303 } 304 305 // directory search 306 char* oldest_user = NULL; 307 time_t oldest_ctime = 0; 308 309 const char* tmpdirname = os::get_temp_directory(); 310 311 DIR* tmpdirp = os::opendir(tmpdirname); 312 313 if (tmpdirp == NULL) { 314 return NULL; 315 } 316 317 // for each entry in the directory that matches the pattern hsperfdata_*, 318 // open the directory and check if the file for the given vmid exists. 319 // The file with the expected name and the latest creation date is used 320 // to determine the user name for the process id. 321 // 322 struct dirent* dentry; 323 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); 324 errno = 0; 325 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 326 327 // check if the directory entry is a hsperfdata file 328 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 329 continue; 330 } 331 332 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 333 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 334 strcpy(usrdir_name, tmpdirname); 335 strcat(usrdir_name, "/"); 336 strcat(usrdir_name, dentry->d_name); 337 338 DIR* subdirp = os::opendir(usrdir_name); 339 340 if (subdirp == NULL) { 341 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 342 continue; 343 } 344 345 // Since we don't create the backing store files in directories 346 // pointed to by symbolic links, we also don't follow them when 347 // looking for the files. We check for a symbolic link after the 348 // call to opendir in order to eliminate a small window where the 349 // symlink can be exploited. 350 // 351 if (!is_directory_secure(usrdir_name)) { 352 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 353 os::closedir(subdirp); 354 continue; 355 } 356 357 struct dirent* udentry; 358 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); 359 errno = 0; 360 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 361 362 if (filename_to_pid(udentry->d_name) == vmid) { 363 struct stat statbuf; 364 int result; 365 366 char* filename = NEW_C_HEAP_ARRAY(char, 367 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 368 369 strcpy(filename, usrdir_name); 370 strcat(filename, "/"); 371 strcat(filename, udentry->d_name); 372 373 // don't follow symbolic links for the file 374 RESTARTABLE(::lstat(filename, &statbuf), result); 375 if (result == OS_ERR) { 376 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 377 continue; 378 } 379 380 // skip over files that are not regular files. 381 if (!S_ISREG(statbuf.st_mode)) { 382 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 383 continue; 384 } 385 386 // compare and save filename with latest creation time 387 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 388 389 if (statbuf.st_ctime > oldest_ctime) { 390 char* user = strchr(dentry->d_name, '_') + 1; 391 392 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user, mtInternal); 393 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 394 395 strcpy(oldest_user, user); 396 oldest_ctime = statbuf.st_ctime; 397 } 398 } 399 400 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 401 } 402 } 403 os::closedir(subdirp); 404 FREE_C_HEAP_ARRAY(char, udbuf, mtInternal); 405 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 406 } 407 os::closedir(tmpdirp); 408 FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal); 409 410 return(oldest_user); 411 } 412 413 // return the name of the user that owns the JVM indicated by the given vmid. 414 // 415 static char* get_user_name(int vmid, TRAPS) { 416 417 char psinfo_name[PATH_MAX]; 418 int result; 419 420 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid); 421 422 RESTARTABLE(::open(psinfo_name, O_RDONLY), result); 423 424 if (result != OS_ERR) { 425 int fd = result; 426 427 psinfo_t psinfo; 428 char* addr = (char*)&psinfo; 429 430 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) { 431 432 RESTARTABLE(::read(fd, addr, remaining), result); 433 if (result == OS_ERR) { 434 ::close(fd); 435 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error"); 436 } else { 437 remaining-=result; 438 addr+=result; 439 } 440 } 441 442 ::close(fd); 443 444 // get the user name for the effective user id of the process 445 char* user_name = get_user_name(psinfo.pr_euid); 446 447 return user_name; 448 } 449 450 if (result == OS_ERR && errno == EACCES) { 451 452 // In this case, the psinfo file for the process id existed, 453 // but we didn't have permission to access it. 454 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 455 strerror(errno)); 456 } 457 458 // at this point, we don't know if the process id itself doesn't 459 // exist or if the psinfo file doesn't exit. If the psinfo file 460 // doesn't exist, then we are running on Solaris 2.5.1 or earlier. 461 // since the structured procfs and old procfs interfaces can't be 462 // mixed, we attempt to find the file through a directory search. 463 464 return get_user_name_slow(vmid, CHECK_NULL); 465 } 466 467 // return the file name of the backing store file for the named 468 // shared memory region for the given user name and vmid. 469 // 470 // the caller is expected to free the allocated memory. 471 // 472 static char* get_sharedmem_filename(const char* dirname, int vmid) { 473 474 // add 2 for the file separator and a NULL terminator. 475 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 476 477 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 478 snprintf(name, nbytes, "%s/%d", dirname, vmid); 479 480 return name; 481 } 482 483 484 // remove file 485 // 486 // this method removes the file specified by the given path 487 // 488 static void remove_file(const char* path) { 489 490 int result; 491 492 // if the file is a directory, the following unlink will fail. since 493 // we don't expect to find directories in the user temp directory, we 494 // won't try to handle this situation. even if accidentially or 495 // maliciously planted, the directory's presence won't hurt anything. 496 // 497 RESTARTABLE(::unlink(path), result); 498 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 499 if (errno != ENOENT) { 500 warning("Could not unlink shared memory backing" 501 " store file %s : %s\n", path, strerror(errno)); 502 } 503 } 504 } 505 506 507 // remove file 508 // 509 // this method removes the file with the given file name in the 510 // named directory. 511 // 512 static void remove_file(const char* dirname, const char* filename) { 513 514 size_t nbytes = strlen(dirname) + strlen(filename) + 2; 515 char* path = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 516 517 strcpy(path, dirname); 518 strcat(path, "/"); 519 strcat(path, filename); 520 521 remove_file(path); 522 523 FREE_C_HEAP_ARRAY(char, path, mtInternal); 524 } 525 526 527 // cleanup stale shared memory resources 528 // 529 // This method attempts to remove all stale shared memory files in 530 // the named user temporary directory. It scans the named directory 531 // for files matching the pattern ^$[0-9]*$. For each file found, the 532 // process id is extracted from the file name and a test is run to 533 // determine if the process is alive. If the process is not alive, 534 // any stale file resources are removed. 535 // 536 static void cleanup_sharedmem_resources(const char* dirname) { 537 538 // open the user temp directory 539 DIR* dirp = os::opendir(dirname); 540 541 if (dirp == NULL) { 542 // directory doesn't exist, so there is nothing to cleanup 543 return; 544 } 545 546 if (!is_directory_secure(dirname)) { 547 // the directory is not a secure directory 548 return; 549 } 550 551 // for each entry in the directory that matches the expected file 552 // name pattern, determine if the file resources are stale and if 553 // so, remove the file resources. Note, instrumented HotSpot processes 554 // for this user may start and/or terminate during this search and 555 // remove or create new files in this directory. The behavior of this 556 // loop under these conditions is dependent upon the implementation of 557 // opendir/readdir. 558 // 559 struct dirent* entry; 560 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); 561 errno = 0; 562 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 563 564 pid_t pid = filename_to_pid(entry->d_name); 565 566 if (pid == 0) { 567 568 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 569 570 // attempt to remove all unexpected files, except "." and ".." 571 remove_file(dirname, entry->d_name); 572 } 573 574 errno = 0; 575 continue; 576 } 577 578 // we now have a file name that converts to a valid integer 579 // that could represent a process id . if this process id 580 // matches the current process id or the process is not running, 581 // then remove the stale file resources. 582 // 583 // process liveness is detected by sending signal number 0 to 584 // the process id (see kill(2)). if kill determines that the 585 // process does not exist, then the file resources are removed. 586 // if kill determines that that we don't have permission to 587 // signal the process, then the file resources are assumed to 588 // be stale and are removed because the resources for such a 589 // process should be in a different user specific directory. 590 // 591 if ((pid == os::current_process_id()) || 592 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 593 594 remove_file(dirname, entry->d_name); 595 } 596 errno = 0; 597 } 598 os::closedir(dirp); 599 FREE_C_HEAP_ARRAY(char, dbuf, mtInternal); 600 } 601 602 // make the user specific temporary directory. Returns true if 603 // the directory exists and is secure upon return. Returns false 604 // if the directory exists but is either a symlink, is otherwise 605 // insecure, or if an error occurred. 606 // 607 static bool make_user_tmp_dir(const char* dirname) { 608 609 // create the directory with 0755 permissions. note that the directory 610 // will be owned by euid::egid, which may not be the same as uid::gid. 611 // 612 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 613 if (errno == EEXIST) { 614 // The directory already exists and was probably created by another 615 // JVM instance. However, this could also be the result of a 616 // deliberate symlink. Verify that the existing directory is safe. 617 // 618 if (!is_directory_secure(dirname)) { 619 // directory is not secure 620 if (PrintMiscellaneous && Verbose) { 621 warning("%s directory is insecure\n", dirname); 622 } 623 return false; 624 } 625 } 626 else { 627 // we encountered some other failure while attempting 628 // to create the directory 629 // 630 if (PrintMiscellaneous && Verbose) { 631 warning("could not create directory %s: %s\n", 632 dirname, strerror(errno)); 633 } 634 return false; 635 } 636 } 637 return true; 638 } 639 640 // create the shared memory file resources 641 // 642 // This method creates the shared memory file with the given size 643 // This method also creates the user specific temporary directory, if 644 // it does not yet exist. 645 // 646 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 647 648 // make the user temporary directory 649 if (!make_user_tmp_dir(dirname)) { 650 // could not make/find the directory or the found directory 651 // was not secure 652 return -1; 653 } 654 655 int result; 656 657 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result); 658 if (result == OS_ERR) { 659 if (PrintMiscellaneous && Verbose) { 660 warning("could not create file %s: %s\n", filename, strerror(errno)); 661 } 662 return -1; 663 } 664 665 // save the file descriptor 666 int fd = result; 667 668 // set the file size 669 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 670 if (result == OS_ERR) { 671 if (PrintMiscellaneous && Verbose) { 672 warning("could not set shared memory file size: %s\n", strerror(errno)); 673 } 674 ::close(fd); 675 return -1; 676 } 677 678 return fd; 679 } 680 681 // open the shared memory file for the given user and vmid. returns 682 // the file descriptor for the open file or -1 if the file could not 683 // be opened. 684 // 685 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 686 687 // open the file 688 int result; 689 RESTARTABLE(::open(filename, oflags), result); 690 if (result == OS_ERR) { 691 if (errno == ENOENT) { 692 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 693 "Process not found", OS_ERR); 694 } 695 else if (errno == EACCES) { 696 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 697 "Permission denied", OS_ERR); 698 } 699 else { 700 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR); 701 } 702 } 703 704 return result; 705 } 706 707 // create a named shared memory region. returns the address of the 708 // memory region on success or NULL on failure. A return value of 709 // NULL will ultimately disable the shared memory feature. 710 // 711 // On Solaris and Linux, the name space for shared memory objects 712 // is the file system name space. 713 // 714 // A monitoring application attaching to a JVM does not need to know 715 // the file system name of the shared memory object. However, it may 716 // be convenient for applications to discover the existence of newly 717 // created and terminating JVMs by watching the file system name space 718 // for files being created or removed. 719 // 720 static char* mmap_create_shared(size_t size) { 721 722 int result; 723 int fd; 724 char* mapAddress; 725 726 int vmid = os::current_process_id(); 727 728 char* user_name = get_user_name(geteuid()); 729 730 if (user_name == NULL) 731 return NULL; 732 733 char* dirname = get_user_tmp_dir(user_name); 734 char* filename = get_sharedmem_filename(dirname, vmid); 735 736 // cleanup any stale shared memory files 737 cleanup_sharedmem_resources(dirname); 738 739 assert(((size > 0) && (size % os::vm_page_size() == 0)), 740 "unexpected PerfMemory region size"); 741 742 fd = create_sharedmem_resources(dirname, filename, size); 743 744 FREE_C_HEAP_ARRAY(char, user_name, mtInternal); 745 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 746 747 if (fd == -1) { 748 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 749 return NULL; 750 } 751 752 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 753 754 result = ::close(fd); 755 assert(result != OS_ERR, "could not close file"); 756 757 if (mapAddress == MAP_FAILED) { 758 if (PrintMiscellaneous && Verbose) { 759 warning("mmap failed - %s\n", strerror(errno)); 760 } 761 remove_file(filename); 762 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 763 return NULL; 764 } 765 766 // save the file name for use in delete_shared_memory() 767 backing_store_file_name = filename; 768 769 // clear the shared memory region 770 (void)::memset((void*) mapAddress, 0, size); 771 772 // it does not go through os api, the operation has to record from here 773 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, mtInternal, CURRENT_PC); 774 775 return mapAddress; 776 } 777 778 // release a named shared memory region 779 // 780 static void unmap_shared(char* addr, size_t bytes) { 781 os::release_memory(addr, bytes); 782 } 783 784 // create the PerfData memory region in shared memory. 785 // 786 static char* create_shared_memory(size_t size) { 787 788 // create the shared memory region. 789 return mmap_create_shared(size); 790 } 791 792 // delete the shared PerfData memory region 793 // 794 static void delete_shared_memory(char* addr, size_t size) { 795 796 // cleanup the persistent shared memory resources. since DestroyJavaVM does 797 // not support unloading of the JVM, unmapping of the memory resource is 798 // not performed. The memory will be reclaimed by the OS upon termination of 799 // the process. The backing store file is deleted from the file system. 800 801 assert(!PerfDisableSharedMem, "shouldn't be here"); 802 803 if (backing_store_file_name != NULL) { 804 remove_file(backing_store_file_name); 805 // Don't.. Free heap memory could deadlock os::abort() if it is called 806 // from signal handler. OS will reclaim the heap memory. 807 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 808 backing_store_file_name = NULL; 809 } 810 } 811 812 // return the size of the file for the given file descriptor 813 // or 0 if it is not a valid size for a shared memory file 814 // 815 static size_t sharedmem_filesize(int fd, TRAPS) { 816 817 struct stat statbuf; 818 int result; 819 820 RESTARTABLE(::fstat(fd, &statbuf), result); 821 if (result == OS_ERR) { 822 if (PrintMiscellaneous && Verbose) { 823 warning("fstat failed: %s\n", strerror(errno)); 824 } 825 THROW_MSG_0(vmSymbols::java_io_IOException(), 826 "Could not determine PerfMemory size"); 827 } 828 829 if ((statbuf.st_size == 0) || 830 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 831 THROW_MSG_0(vmSymbols::java_lang_Exception(), 832 "Invalid PerfMemory size"); 833 } 834 835 return (size_t)statbuf.st_size; 836 } 837 838 // attach to a named shared memory region. 839 // 840 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 841 842 char* mapAddress; 843 int result; 844 int fd; 845 size_t size = 0; 846 const char* luser = NULL; 847 848 int mmap_prot; 849 int file_flags; 850 851 ResourceMark rm; 852 853 // map the high level access mode to the appropriate permission 854 // constructs for the file and the shared memory mapping. 855 if (mode == PerfMemory::PERF_MODE_RO) { 856 mmap_prot = PROT_READ; 857 file_flags = O_RDONLY; 858 } 859 else if (mode == PerfMemory::PERF_MODE_RW) { 860 #ifdef LATER 861 mmap_prot = PROT_READ | PROT_WRITE; 862 file_flags = O_RDWR; 863 #else 864 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 865 "Unsupported access mode"); 866 #endif 867 } 868 else { 869 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 870 "Illegal access mode"); 871 } 872 873 if (user == NULL || strlen(user) == 0) { 874 luser = get_user_name(vmid, CHECK); 875 } 876 else { 877 luser = user; 878 } 879 880 if (luser == NULL) { 881 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 882 "Could not map vmid to user Name"); 883 } 884 885 char* dirname = get_user_tmp_dir(luser); 886 887 // since we don't follow symbolic links when creating the backing 888 // store file, we don't follow them when attaching either. 889 // 890 if (!is_directory_secure(dirname)) { 891 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 892 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 893 "Process not found"); 894 } 895 896 char* filename = get_sharedmem_filename(dirname, vmid); 897 898 // copy heap memory to resource memory. the open_sharedmem_file 899 // method below need to use the filename, but could throw an 900 // exception. using a resource array prevents the leak that 901 // would otherwise occur. 902 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 903 strcpy(rfilename, filename); 904 905 // free the c heap resources that are no longer needed 906 if (luser != user) FREE_C_HEAP_ARRAY(char, luser, mtInternal); 907 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 908 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 909 910 // open the shared memory file for the give vmid 911 fd = open_sharedmem_file(rfilename, file_flags, THREAD); 912 913 if (fd == OS_ERR) { 914 return; 915 } 916 917 if (HAS_PENDING_EXCEPTION) { 918 ::close(fd); 919 return; 920 } 921 922 if (*sizep == 0) { 923 size = sharedmem_filesize(fd, CHECK); 924 } else { 925 size = *sizep; 926 } 927 928 assert(size > 0, "unexpected size <= 0"); 929 930 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 931 932 result = ::close(fd); 933 assert(result != OS_ERR, "could not close file"); 934 935 if (mapAddress == MAP_FAILED) { 936 if (PrintMiscellaneous && Verbose) { 937 warning("mmap failed: %s\n", strerror(errno)); 938 } 939 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 940 "Could not map PerfMemory"); 941 } 942 943 // it does not go through os api, the operation has to record from here 944 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, mtInternal, CURRENT_PC); 945 946 *addr = mapAddress; 947 *sizep = size; 948 949 if (PerfTraceMemOps) { 950 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 951 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress); 952 } 953 } 954 955 956 957 958 // create the PerfData memory region 959 // 960 // This method creates the memory region used to store performance 961 // data for the JVM. The memory may be created in standard or 962 // shared memory. 963 // 964 void PerfMemory::create_memory_region(size_t size) { 965 966 if (PerfDisableSharedMem) { 967 // do not share the memory for the performance data. 968 _start = create_standard_memory(size); 969 } 970 else { 971 _start = create_shared_memory(size); 972 if (_start == NULL) { 973 974 // creation of the shared memory region failed, attempt 975 // to create a contiguous, non-shared memory region instead. 976 // 977 if (PrintMiscellaneous && Verbose) { 978 warning("Reverting to non-shared PerfMemory region.\n"); 979 } 980 PerfDisableSharedMem = true; 981 _start = create_standard_memory(size); 982 } 983 } 984 985 if (_start != NULL) _capacity = size; 986 987 } 988 989 // delete the PerfData memory region 990 // 991 // This method deletes the memory region used to store performance 992 // data for the JVM. The memory region indicated by the <address, size> 993 // tuple will be inaccessible after a call to this method. 994 // 995 void PerfMemory::delete_memory_region() { 996 997 assert((start() != NULL && capacity() > 0), "verify proper state"); 998 999 // If user specifies PerfDataSaveFile, it will save the performance data 1000 // to the specified file name no matter whether PerfDataSaveToFile is specified 1001 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1002 // -XX:+PerfDataSaveToFile. 1003 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1004 save_memory_to_file(start(), capacity()); 1005 } 1006 1007 if (PerfDisableSharedMem) { 1008 delete_standard_memory(start(), capacity()); 1009 } 1010 else { 1011 delete_shared_memory(start(), capacity()); 1012 } 1013 } 1014 1015 // attach to the PerfData memory region for another JVM 1016 // 1017 // This method returns an <address, size> tuple that points to 1018 // a memory buffer that is kept reasonably synchronized with 1019 // the PerfData memory region for the indicated JVM. This 1020 // buffer may be kept in synchronization via shared memory 1021 // or some other mechanism that keeps the buffer updated. 1022 // 1023 // If the JVM chooses not to support the attachability feature, 1024 // this method should throw an UnsupportedOperation exception. 1025 // 1026 // This implementation utilizes named shared memory to map 1027 // the indicated process's PerfData memory region into this JVMs 1028 // address space. 1029 // 1030 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1031 1032 if (vmid == 0 || vmid == os::current_process_id()) { 1033 *addrp = start(); 1034 *sizep = capacity(); 1035 return; 1036 } 1037 1038 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1039 } 1040 1041 // detach from the PerfData memory region of another JVM 1042 // 1043 // This method detaches the PerfData memory region of another 1044 // JVM, specified as an <address, size> tuple of a buffer 1045 // in this process's address space. This method may perform 1046 // arbitrary actions to accomplish the detachment. The memory 1047 // region specified by <address, size> will be inaccessible after 1048 // a call to this method. 1049 // 1050 // If the JVM chooses not to support the attachability feature, 1051 // this method should throw an UnsupportedOperation exception. 1052 // 1053 // This implementation utilizes named shared memory to detach 1054 // the indicated process's PerfData memory region from this 1055 // process's address space. 1056 // 1057 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1058 1059 assert(addr != 0, "address sanity check"); 1060 assert(bytes > 0, "capacity sanity check"); 1061 1062 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1063 // prevent accidental detachment of this process's PerfMemory region 1064 return; 1065 } 1066 1067 unmap_shared(addr, bytes); 1068 } 1069 1070 char* PerfMemory::backing_store_filename() { 1071 return backing_store_file_name; 1072 }