perfMemory_solaris.cpp revision 0:a61af66fc99e
1/* 2 * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 20 * CA 95054 USA or visit www.sun.com if you need additional information or 21 * have any questions. 22 * 23 */ 24 25# include "incls/_precompiled.incl" 26# include "incls/_perfMemory_solaris.cpp.incl" 27 28// put OS-includes here 29# include <sys/types.h> 30# include <sys/mman.h> 31# include <errno.h> 32# include <stdio.h> 33# include <unistd.h> 34# include <sys/stat.h> 35# include <signal.h> 36# include <pwd.h> 37# include <procfs.h> 38 39 40static char* backing_store_file_name = NULL; // name of the backing store 41 // file, if successfully created. 42 43// Standard Memory Implementation Details 44 45// create the PerfData memory region in standard memory. 46// 47static char* create_standard_memory(size_t size) { 48 49 // allocate an aligned chuck of memory 50 char* mapAddress = os::reserve_memory(size); 51 52 if (mapAddress == NULL) { 53 return NULL; 54 } 55 56 // commit memory 57 if (!os::commit_memory(mapAddress, size)) { 58 if (PrintMiscellaneous && Verbose) { 59 warning("Could not commit PerfData memory\n"); 60 } 61 os::release_memory(mapAddress, size); 62 return NULL; 63 } 64 65 return mapAddress; 66} 67 68// delete the PerfData memory region 69// 70static void delete_standard_memory(char* addr, size_t size) { 71 72 // there are no persistent external resources to cleanup for standard 73 // memory. since DestroyJavaVM does not support unloading of the JVM, 74 // cleanup of the memory resource is not performed. The memory will be 75 // reclaimed by the OS upon termination of the process. 76 // 77 return; 78} 79 80// save the specified memory region to the given file 81// 82// Note: this function might be called from signal handler (by os::abort()), 83// don't allocate heap memory. 84// 85static void save_memory_to_file(char* addr, size_t size) { 86 87 const char* destfile = PerfMemory::get_perfdata_file_path(); 88 assert(destfile[0] != '\0', "invalid PerfData file path"); 89 90 int result; 91 92 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 93 result);; 94 if (result == OS_ERR) { 95 if (PrintMiscellaneous && Verbose) { 96 warning("Could not create Perfdata save file: %s: %s\n", 97 destfile, strerror(errno)); 98 } 99 } else { 100 101 int fd = result; 102 103 for (size_t remaining = size; remaining > 0;) { 104 105 RESTARTABLE(::write(fd, addr, remaining), result); 106 if (result == OS_ERR) { 107 if (PrintMiscellaneous && Verbose) { 108 warning("Could not write Perfdata save file: %s: %s\n", 109 destfile, strerror(errno)); 110 } 111 break; 112 } 113 remaining -= (size_t)result; 114 addr += result; 115 } 116 117 RESTARTABLE(::close(fd), result); 118 if (PrintMiscellaneous && Verbose) { 119 if (result == OS_ERR) { 120 warning("Could not close %s: %s\n", destfile, strerror(errno)); 121 } 122 } 123 } 124 FREE_C_HEAP_ARRAY(char, destfile); 125} 126 127 128// Shared Memory Implementation Details 129 130// Note: the solaris and linux shared memory implementation uses the mmap 131// interface with a backing store file to implement named shared memory. 132// Using the file system as the name space for shared memory allows a 133// common name space to be supported across a variety of platforms. It 134// also provides a name space that Java applications can deal with through 135// simple file apis. 136// 137// The solaris and linux implementations store the backing store file in 138// a user specific temporary directory located in the /tmp file system, 139// which is always a local file system and is sometimes a RAM based file 140// system. 141 142// return the user specific temporary directory name. 143// 144// the caller is expected to free the allocated memory. 145// 146static char* get_user_tmp_dir(const char* user) { 147 148 const char* tmpdir = os::get_temp_directory(); 149 const char* perfdir = PERFDATA_NAME; 150 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 2; 151 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes); 152 153 // construct the path name to user specific tmp directory 154 snprintf(dirname, nbytes, "%s%s_%s", tmpdir, perfdir, user); 155 156 return dirname; 157} 158 159// convert the given file name into a process id. if the file 160// does not meet the file naming constraints, return 0. 161// 162static pid_t filename_to_pid(const char* filename) { 163 164 // a filename that doesn't begin with a digit is not a 165 // candidate for conversion. 166 // 167 if (!isdigit(*filename)) { 168 return 0; 169 } 170 171 // check if file name can be converted to an integer without 172 // any leftover characters. 173 // 174 char* remainder = NULL; 175 errno = 0; 176 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 177 178 if (errno != 0) { 179 return 0; 180 } 181 182 // check for left over characters. If any, then the filename is 183 // not a candidate for conversion. 184 // 185 if (remainder != NULL && *remainder != '\0') { 186 return 0; 187 } 188 189 // successful conversion, return the pid 190 return pid; 191} 192 193 194// check if the given path is considered a secure directory for 195// the backing store files. Returns true if the directory exists 196// and is considered a secure location. Returns false if the path 197// is a symbolic link or if an error occured. 198// 199static bool is_directory_secure(const char* path) { 200 struct stat statbuf; 201 int result = 0; 202 203 RESTARTABLE(::lstat(path, &statbuf), result); 204 if (result == OS_ERR) { 205 return false; 206 } 207 208 // the path exists, now check it's mode 209 if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) { 210 // the path represents a link or some non-directory file type, 211 // which is not what we expected. declare it insecure. 212 // 213 return false; 214 } 215 else { 216 // we have an existing directory, check if the permissions are safe. 217 // 218 if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) { 219 // the directory is open for writing and could be subjected 220 // to a symlnk attack. declare it insecure. 221 // 222 return false; 223 } 224 } 225 return true; 226} 227 228 229// return the user name for the given user id 230// 231// the caller is expected to free the allocated memory. 232// 233static char* get_user_name(uid_t uid) { 234 235 struct passwd pwent; 236 237 // determine the max pwbuf size from sysconf, and hardcode 238 // a default if this not available through sysconf. 239 // 240 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 241 if (bufsize == -1) 242 bufsize = 1024; 243 244 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize); 245 246#ifdef _GNU_SOURCE 247 struct passwd* p = NULL; 248 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 249#else // _GNU_SOURCE 250 struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize); 251#endif // _GNU_SOURCE 252 253 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 254 if (PrintMiscellaneous && Verbose) { 255 if (p == NULL) { 256 warning("Could not retrieve passwd entry: %s\n", 257 strerror(errno)); 258 } 259 else { 260 warning("Could not determine user name: %s\n", 261 p->pw_name == NULL ? "pw_name = NULL" : 262 "pw_name zero length"); 263 } 264 } 265 FREE_C_HEAP_ARRAY(char, pwbuf); 266 return NULL; 267 } 268 269 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1); 270 strcpy(user_name, p->pw_name); 271 272 FREE_C_HEAP_ARRAY(char, pwbuf); 273 return user_name; 274} 275 276// return the name of the user that owns the process identified by vmid. 277// 278// This method uses a slow directory search algorithm to find the backing 279// store file for the specified vmid and returns the user name, as determined 280// by the user name suffix of the hsperfdata_<username> directory name. 281// 282// the caller is expected to free the allocated memory. 283// 284static char* get_user_name_slow(int vmid, TRAPS) { 285 286 // short circuit the directory search if the process doesn't even exist. 287 if (kill(vmid, 0) == OS_ERR) { 288 if (errno == ESRCH) { 289 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 290 "Process not found"); 291 } 292 else /* EPERM */ { 293 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 294 } 295 } 296 297 // directory search 298 char* oldest_user = NULL; 299 time_t oldest_ctime = 0; 300 301 const char* tmpdirname = os::get_temp_directory(); 302 303 DIR* tmpdirp = os::opendir(tmpdirname); 304 305 if (tmpdirp == NULL) { 306 return NULL; 307 } 308 309 // for each entry in the directory that matches the pattern hsperfdata_*, 310 // open the directory and check if the file for the given vmid exists. 311 // The file with the expected name and the latest creation date is used 312 // to determine the user name for the process id. 313 // 314 struct dirent* dentry; 315 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname)); 316 errno = 0; 317 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 318 319 // check if the directory entry is a hsperfdata file 320 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 321 continue; 322 } 323 324 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 325 strlen(tmpdirname) + strlen(dentry->d_name) + 1); 326 strcpy(usrdir_name, tmpdirname); 327 strcat(usrdir_name, dentry->d_name); 328 329 DIR* subdirp = os::opendir(usrdir_name); 330 331 if (subdirp == NULL) { 332 FREE_C_HEAP_ARRAY(char, usrdir_name); 333 continue; 334 } 335 336 // Since we don't create the backing store files in directories 337 // pointed to by symbolic links, we also don't follow them when 338 // looking for the files. We check for a symbolic link after the 339 // call to opendir in order to eliminate a small window where the 340 // symlink can be exploited. 341 // 342 if (!is_directory_secure(usrdir_name)) { 343 FREE_C_HEAP_ARRAY(char, usrdir_name); 344 os::closedir(subdirp); 345 continue; 346 } 347 348 struct dirent* udentry; 349 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name)); 350 errno = 0; 351 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 352 353 if (filename_to_pid(udentry->d_name) == vmid) { 354 struct stat statbuf; 355 int result; 356 357 char* filename = NEW_C_HEAP_ARRAY(char, 358 strlen(usrdir_name) + strlen(udentry->d_name) + 2); 359 360 strcpy(filename, usrdir_name); 361 strcat(filename, "/"); 362 strcat(filename, udentry->d_name); 363 364 // don't follow symbolic links for the file 365 RESTARTABLE(::lstat(filename, &statbuf), result); 366 if (result == OS_ERR) { 367 FREE_C_HEAP_ARRAY(char, filename); 368 continue; 369 } 370 371 // skip over files that are not regular files. 372 if (!S_ISREG(statbuf.st_mode)) { 373 FREE_C_HEAP_ARRAY(char, filename); 374 continue; 375 } 376 377 // compare and save filename with latest creation time 378 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 379 380 if (statbuf.st_ctime > oldest_ctime) { 381 char* user = strchr(dentry->d_name, '_') + 1; 382 383 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); 384 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1); 385 386 strcpy(oldest_user, user); 387 oldest_ctime = statbuf.st_ctime; 388 } 389 } 390 391 FREE_C_HEAP_ARRAY(char, filename); 392 } 393 } 394 os::closedir(subdirp); 395 FREE_C_HEAP_ARRAY(char, udbuf); 396 FREE_C_HEAP_ARRAY(char, usrdir_name); 397 } 398 os::closedir(tmpdirp); 399 FREE_C_HEAP_ARRAY(char, tdbuf); 400 401 return(oldest_user); 402} 403 404// return the name of the user that owns the JVM indicated by the given vmid. 405// 406static char* get_user_name(int vmid, TRAPS) { 407 408 char psinfo_name[PATH_MAX]; 409 int result; 410 411 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid); 412 413 RESTARTABLE(::open(psinfo_name, O_RDONLY), result); 414 415 if (result != OS_ERR) { 416 int fd = result; 417 418 psinfo_t psinfo; 419 char* addr = (char*)&psinfo; 420 421 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) { 422 423 RESTARTABLE(::read(fd, addr, remaining), result); 424 if (result == OS_ERR) { 425 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error"); 426 } 427 remaining-=result; 428 addr+=result; 429 } 430 431 RESTARTABLE(::close(fd), result); 432 433 // get the user name for the effective user id of the process 434 char* user_name = get_user_name(psinfo.pr_euid); 435 436 return user_name; 437 } 438 439 if (result == OS_ERR && errno == EACCES) { 440 441 // In this case, the psinfo file for the process id existed, 442 // but we didn't have permission to access it. 443 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 444 strerror(errno)); 445 } 446 447 // at this point, we don't know if the process id itself doesn't 448 // exist or if the psinfo file doesn't exit. If the psinfo file 449 // doesn't exist, then we are running on Solaris 2.5.1 or earlier. 450 // since the structured procfs and old procfs interfaces can't be 451 // mixed, we attempt to find the file through a directory search. 452 453 return get_user_name_slow(vmid, CHECK_NULL); 454} 455 456// return the file name of the backing store file for the named 457// shared memory region for the given user name and vmid. 458// 459// the caller is expected to free the allocated memory. 460// 461static char* get_sharedmem_filename(const char* dirname, int vmid) { 462 463 // add 2 for the file separator and a NULL terminator. 464 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 465 466 char* name = NEW_C_HEAP_ARRAY(char, nbytes); 467 snprintf(name, nbytes, "%s/%d", dirname, vmid); 468 469 return name; 470} 471 472 473// remove file 474// 475// this method removes the file specified by the given path 476// 477static void remove_file(const char* path) { 478 479 int result; 480 481 // if the file is a directory, the following unlink will fail. since 482 // we don't expect to find directories in the user temp directory, we 483 // won't try to handle this situation. even if accidentially or 484 // maliciously planted, the directory's presence won't hurt anything. 485 // 486 RESTARTABLE(::unlink(path), result); 487 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 488 if (errno != ENOENT) { 489 warning("Could not unlink shared memory backing" 490 " store file %s : %s\n", path, strerror(errno)); 491 } 492 } 493} 494 495 496// remove file 497// 498// this method removes the file with the given file name in the 499// named directory. 500// 501static void remove_file(const char* dirname, const char* filename) { 502 503 size_t nbytes = strlen(dirname) + strlen(filename) + 2; 504 char* path = NEW_C_HEAP_ARRAY(char, nbytes); 505 506 strcpy(path, dirname); 507 strcat(path, "/"); 508 strcat(path, filename); 509 510 remove_file(path); 511 512 FREE_C_HEAP_ARRAY(char, path); 513} 514 515 516// cleanup stale shared memory resources 517// 518// This method attempts to remove all stale shared memory files in 519// the named user temporary directory. It scans the named directory 520// for files matching the pattern ^$[0-9]*$. For each file found, the 521// process id is extracted from the file name and a test is run to 522// determine if the process is alive. If the process is not alive, 523// any stale file resources are removed. 524// 525static void cleanup_sharedmem_resources(const char* dirname) { 526 527 // open the user temp directory 528 DIR* dirp = os::opendir(dirname); 529 530 if (dirp == NULL) { 531 // directory doesn't exist, so there is nothing to cleanup 532 return; 533 } 534 535 if (!is_directory_secure(dirname)) { 536 // the directory is not a secure directory 537 return; 538 } 539 540 // for each entry in the directory that matches the expected file 541 // name pattern, determine if the file resources are stale and if 542 // so, remove the file resources. Note, instrumented HotSpot processes 543 // for this user may start and/or terminate during this search and 544 // remove or create new files in this directory. The behavior of this 545 // loop under these conditions is dependent upon the implementation of 546 // opendir/readdir. 547 // 548 struct dirent* entry; 549 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname)); 550 errno = 0; 551 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 552 553 pid_t pid = filename_to_pid(entry->d_name); 554 555 if (pid == 0) { 556 557 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 558 559 // attempt to remove all unexpected files, except "." and ".." 560 remove_file(dirname, entry->d_name); 561 } 562 563 errno = 0; 564 continue; 565 } 566 567 // we now have a file name that converts to a valid integer 568 // that could represent a process id . if this process id 569 // matches the current process id or the process is not running, 570 // then remove the stale file resources. 571 // 572 // process liveness is detected by sending signal number 0 to 573 // the process id (see kill(2)). if kill determines that the 574 // process does not exist, then the file resources are removed. 575 // if kill determines that that we don't have permission to 576 // signal the process, then the file resources are assumed to 577 // be stale and are removed because the resources for such a 578 // process should be in a different user specific directory. 579 // 580 if ((pid == os::current_process_id()) || 581 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 582 583 remove_file(dirname, entry->d_name); 584 } 585 errno = 0; 586 } 587 os::closedir(dirp); 588 FREE_C_HEAP_ARRAY(char, dbuf); 589} 590 591// make the user specific temporary directory. Returns true if 592// the directory exists and is secure upon return. Returns false 593// if the directory exists but is either a symlink, is otherwise 594// insecure, or if an error occurred. 595// 596static bool make_user_tmp_dir(const char* dirname) { 597 598 // create the directory with 0755 permissions. note that the directory 599 // will be owned by euid::egid, which may not be the same as uid::gid. 600 // 601 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 602 if (errno == EEXIST) { 603 // The directory already exists and was probably created by another 604 // JVM instance. However, this could also be the result of a 605 // deliberate symlink. Verify that the existing directory is safe. 606 // 607 if (!is_directory_secure(dirname)) { 608 // directory is not secure 609 if (PrintMiscellaneous && Verbose) { 610 warning("%s directory is insecure\n", dirname); 611 } 612 return false; 613 } 614 } 615 else { 616 // we encountered some other failure while attempting 617 // to create the directory 618 // 619 if (PrintMiscellaneous && Verbose) { 620 warning("could not create directory %s: %s\n", 621 dirname, strerror(errno)); 622 } 623 return false; 624 } 625 } 626 return true; 627} 628 629// create the shared memory file resources 630// 631// This method creates the shared memory file with the given size 632// This method also creates the user specific temporary directory, if 633// it does not yet exist. 634// 635static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 636 637 // make the user temporary directory 638 if (!make_user_tmp_dir(dirname)) { 639 // could not make/find the directory or the found directory 640 // was not secure 641 return -1; 642 } 643 644 int result; 645 646 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result); 647 if (result == OS_ERR) { 648 if (PrintMiscellaneous && Verbose) { 649 warning("could not create file %s: %s\n", filename, strerror(errno)); 650 } 651 return -1; 652 } 653 654 // save the file descriptor 655 int fd = result; 656 657 // set the file size 658 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 659 if (result == OS_ERR) { 660 if (PrintMiscellaneous && Verbose) { 661 warning("could not set shared memory file size: %s\n", strerror(errno)); 662 } 663 RESTARTABLE(::close(fd), result); 664 return -1; 665 } 666 667 return fd; 668} 669 670// open the shared memory file for the given user and vmid. returns 671// the file descriptor for the open file or -1 if the file could not 672// be opened. 673// 674static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 675 676 // open the file 677 int result; 678 RESTARTABLE(::open(filename, oflags), result); 679 if (result == OS_ERR) { 680 if (errno == ENOENT) { 681 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 682 "Process not found"); 683 } 684 else if (errno == EACCES) { 685 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 686 "Permission denied"); 687 } 688 else { 689 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 690 } 691 } 692 693 return result; 694} 695 696// create a named shared memory region. returns the address of the 697// memory region on success or NULL on failure. A return value of 698// NULL will ultimately disable the shared memory feature. 699// 700// On Solaris and Linux, the name space for shared memory objects 701// is the file system name space. 702// 703// A monitoring application attaching to a JVM does not need to know 704// the file system name of the shared memory object. However, it may 705// be convenient for applications to discover the existence of newly 706// created and terminating JVMs by watching the file system name space 707// for files being created or removed. 708// 709static char* mmap_create_shared(size_t size) { 710 711 int result; 712 int fd; 713 char* mapAddress; 714 715 int vmid = os::current_process_id(); 716 717 char* user_name = get_user_name(geteuid()); 718 719 if (user_name == NULL) 720 return NULL; 721 722 char* dirname = get_user_tmp_dir(user_name); 723 char* filename = get_sharedmem_filename(dirname, vmid); 724 725 // cleanup any stale shared memory files 726 cleanup_sharedmem_resources(dirname); 727 728 assert(((size > 0) && (size % os::vm_page_size() == 0)), 729 "unexpected PerfMemory region size"); 730 731 fd = create_sharedmem_resources(dirname, filename, size); 732 733 FREE_C_HEAP_ARRAY(char, user_name); 734 FREE_C_HEAP_ARRAY(char, dirname); 735 736 if (fd == -1) { 737 FREE_C_HEAP_ARRAY(char, filename); 738 return NULL; 739 } 740 741 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 742 743 // attempt to close the file - restart it if it was interrupted, 744 // but ignore other failures 745 RESTARTABLE(::close(fd), result); 746 assert(result != OS_ERR, "could not close file"); 747 748 if (mapAddress == MAP_FAILED) { 749 if (PrintMiscellaneous && Verbose) { 750 warning("mmap failed - %s\n", strerror(errno)); 751 } 752 remove_file(filename); 753 FREE_C_HEAP_ARRAY(char, filename); 754 return NULL; 755 } 756 757 // save the file name for use in delete_shared_memory() 758 backing_store_file_name = filename; 759 760 // clear the shared memory region 761 (void)::memset((void*) mapAddress, 0, size); 762 763 return mapAddress; 764} 765 766// release a named shared memory region 767// 768static void unmap_shared(char* addr, size_t bytes) { 769 os::release_memory(addr, bytes); 770} 771 772// create the PerfData memory region in shared memory. 773// 774static char* create_shared_memory(size_t size) { 775 776 // create the shared memory region. 777 return mmap_create_shared(size); 778} 779 780// delete the shared PerfData memory region 781// 782static void delete_shared_memory(char* addr, size_t size) { 783 784 // cleanup the persistent shared memory resources. since DestroyJavaVM does 785 // not support unloading of the JVM, unmapping of the memory resource is 786 // not performed. The memory will be reclaimed by the OS upon termination of 787 // the process. The backing store file is deleted from the file system. 788 789 assert(!PerfDisableSharedMem, "shouldn't be here"); 790 791 if (backing_store_file_name != NULL) { 792 remove_file(backing_store_file_name); 793 // Don't.. Free heap memory could deadlock os::abort() if it is called 794 // from signal handler. OS will reclaim the heap memory. 795 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 796 backing_store_file_name = NULL; 797 } 798} 799 800// return the size of the file for the given file descriptor 801// or 0 if it is not a valid size for a shared memory file 802// 803static size_t sharedmem_filesize(int fd, TRAPS) { 804 805 struct stat statbuf; 806 int result; 807 808 RESTARTABLE(::fstat(fd, &statbuf), result); 809 if (result == OS_ERR) { 810 if (PrintMiscellaneous && Verbose) { 811 warning("fstat failed: %s\n", strerror(errno)); 812 } 813 THROW_MSG_0(vmSymbols::java_io_IOException(), 814 "Could not determine PerfMemory size"); 815 } 816 817 if ((statbuf.st_size == 0) || 818 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 819 THROW_MSG_0(vmSymbols::java_lang_Exception(), 820 "Invalid PerfMemory size"); 821 } 822 823 return (size_t)statbuf.st_size; 824} 825 826// attach to a named shared memory region. 827// 828static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 829 830 char* mapAddress; 831 int result; 832 int fd; 833 size_t size; 834 const char* luser = NULL; 835 836 int mmap_prot; 837 int file_flags; 838 839 ResourceMark rm; 840 841 // map the high level access mode to the appropriate permission 842 // constructs for the file and the shared memory mapping. 843 if (mode == PerfMemory::PERF_MODE_RO) { 844 mmap_prot = PROT_READ; 845 file_flags = O_RDONLY; 846 } 847 else if (mode == PerfMemory::PERF_MODE_RW) { 848#ifdef LATER 849 mmap_prot = PROT_READ | PROT_WRITE; 850 file_flags = O_RDWR; 851#else 852 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 853 "Unsupported access mode"); 854#endif 855 } 856 else { 857 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 858 "Illegal access mode"); 859 } 860 861 if (user == NULL || strlen(user) == 0) { 862 luser = get_user_name(vmid, CHECK); 863 } 864 else { 865 luser = user; 866 } 867 868 if (luser == NULL) { 869 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 870 "Could not map vmid to user Name"); 871 } 872 873 char* dirname = get_user_tmp_dir(luser); 874 875 // since we don't follow symbolic links when creating the backing 876 // store file, we don't follow them when attaching either. 877 // 878 if (!is_directory_secure(dirname)) { 879 FREE_C_HEAP_ARRAY(char, dirname); 880 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 881 "Process not found"); 882 } 883 884 char* filename = get_sharedmem_filename(dirname, vmid); 885 886 // copy heap memory to resource memory. the open_sharedmem_file 887 // method below need to use the filename, but could throw an 888 // exception. using a resource array prevents the leak that 889 // would otherwise occur. 890 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 891 strcpy(rfilename, filename); 892 893 // free the c heap resources that are no longer needed 894 if (luser != user) FREE_C_HEAP_ARRAY(char, luser); 895 FREE_C_HEAP_ARRAY(char, dirname); 896 FREE_C_HEAP_ARRAY(char, filename); 897 898 // open the shared memory file for the give vmid 899 fd = open_sharedmem_file(rfilename, file_flags, CHECK); 900 assert(fd != OS_ERR, "unexpected value"); 901 902 if (*sizep == 0) { 903 size = sharedmem_filesize(fd, CHECK); 904 assert(size != 0, "unexpected size"); 905 } 906 907 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 908 909 // attempt to close the file - restart if it gets interrupted, 910 // but ignore other failures 911 RESTARTABLE(::close(fd), result); 912 assert(result != OS_ERR, "could not close file"); 913 914 if (mapAddress == MAP_FAILED) { 915 if (PrintMiscellaneous && Verbose) { 916 warning("mmap failed: %s\n", strerror(errno)); 917 } 918 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 919 "Could not map PerfMemory"); 920 } 921 922 *addr = mapAddress; 923 *sizep = size; 924 925 if (PerfTraceMemOps) { 926 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 927 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress); 928 } 929} 930 931 932 933 934// create the PerfData memory region 935// 936// This method creates the memory region used to store performance 937// data for the JVM. The memory may be created in standard or 938// shared memory. 939// 940void PerfMemory::create_memory_region(size_t size) { 941 942 if (PerfDisableSharedMem) { 943 // do not share the memory for the performance data. 944 _start = create_standard_memory(size); 945 } 946 else { 947 _start = create_shared_memory(size); 948 if (_start == NULL) { 949 950 // creation of the shared memory region failed, attempt 951 // to create a contiguous, non-shared memory region instead. 952 // 953 if (PrintMiscellaneous && Verbose) { 954 warning("Reverting to non-shared PerfMemory region.\n"); 955 } 956 PerfDisableSharedMem = true; 957 _start = create_standard_memory(size); 958 } 959 } 960 961 if (_start != NULL) _capacity = size; 962 963} 964 965// delete the PerfData memory region 966// 967// This method deletes the memory region used to store performance 968// data for the JVM. The memory region indicated by the <address, size> 969// tuple will be inaccessible after a call to this method. 970// 971void PerfMemory::delete_memory_region() { 972 973 assert((start() != NULL && capacity() > 0), "verify proper state"); 974 975 // If user specifies PerfDataSaveFile, it will save the performance data 976 // to the specified file name no matter whether PerfDataSaveToFile is specified 977 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 978 // -XX:+PerfDataSaveToFile. 979 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 980 save_memory_to_file(start(), capacity()); 981 } 982 983 if (PerfDisableSharedMem) { 984 delete_standard_memory(start(), capacity()); 985 } 986 else { 987 delete_shared_memory(start(), capacity()); 988 } 989} 990 991// attach to the PerfData memory region for another JVM 992// 993// This method returns an <address, size> tuple that points to 994// a memory buffer that is kept reasonably synchronized with 995// the PerfData memory region for the indicated JVM. This 996// buffer may be kept in synchronization via shared memory 997// or some other mechanism that keeps the buffer updated. 998// 999// If the JVM chooses not to support the attachability feature, 1000// this method should throw an UnsupportedOperation exception. 1001// 1002// This implementation utilizes named shared memory to map 1003// the indicated process's PerfData memory region into this JVMs 1004// address space. 1005// 1006void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1007 1008 if (vmid == 0 || vmid == os::current_process_id()) { 1009 *addrp = start(); 1010 *sizep = capacity(); 1011 return; 1012 } 1013 1014 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1015} 1016 1017// detach from the PerfData memory region of another JVM 1018// 1019// This method detaches the PerfData memory region of another 1020// JVM, specified as an <address, size> tuple of a buffer 1021// in this process's address space. This method may perform 1022// arbitrary actions to accomplish the detachment. The memory 1023// region specified by <address, size> will be inaccessible after 1024// a call to this method. 1025// 1026// If the JVM chooses not to support the attachability feature, 1027// this method should throw an UnsupportedOperation exception. 1028// 1029// This implementation utilizes named shared memory to detach 1030// the indicated process's PerfData memory region from this 1031// process's address space. 1032// 1033void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1034 1035 assert(addr != 0, "address sanity check"); 1036 assert(bytes > 0, "capacity sanity check"); 1037 1038 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1039 // prevent accidental detachment of this process's PerfMemory region 1040 return; 1041 } 1042 1043 unmap_shared(addr, bytes); 1044} 1045 1046char* PerfMemory::backing_store_filename() { 1047 return backing_store_file_name; 1048} 1049