perfMemory_solaris.cpp revision 1879:f95d63e2154a
1/* 2 * Copyright (c) 2001, 2010, 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 "utilities/exceptions.hpp" 34 35// put OS-includes here 36# include <sys/types.h> 37# include <sys/mman.h> 38# include <errno.h> 39# include <stdio.h> 40# include <unistd.h> 41# include <sys/stat.h> 42# include <signal.h> 43# include <pwd.h> 44# include <procfs.h> 45 46 47static char* backing_store_file_name = NULL; // name of the backing store 48 // file, if successfully created. 49 50// Standard Memory Implementation Details 51 52// create the PerfData memory region in standard memory. 53// 54static char* create_standard_memory(size_t size) { 55 56 // allocate an aligned chuck of memory 57 char* mapAddress = os::reserve_memory(size); 58 59 if (mapAddress == NULL) { 60 return NULL; 61 } 62 63 // commit memory 64 if (!os::commit_memory(mapAddress, size)) { 65 if (PrintMiscellaneous && Verbose) { 66 warning("Could not commit PerfData memory\n"); 67 } 68 os::release_memory(mapAddress, size); 69 return NULL; 70 } 71 72 return mapAddress; 73} 74 75// delete the PerfData memory region 76// 77static void delete_standard_memory(char* addr, size_t size) { 78 79 // there are no persistent external resources to cleanup for standard 80 // memory. since DestroyJavaVM does not support unloading of the JVM, 81 // cleanup of the memory resource is not performed. The memory will be 82 // reclaimed by the OS upon termination of the process. 83 // 84 return; 85} 86 87// save the specified memory region to the given file 88// 89// Note: this function might be called from signal handler (by os::abort()), 90// don't allocate heap memory. 91// 92static void save_memory_to_file(char* addr, size_t size) { 93 94 const char* destfile = PerfMemory::get_perfdata_file_path(); 95 assert(destfile[0] != '\0', "invalid PerfData file path"); 96 97 int result; 98 99 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 100 result);; 101 if (result == OS_ERR) { 102 if (PrintMiscellaneous && Verbose) { 103 warning("Could not create Perfdata save file: %s: %s\n", 104 destfile, strerror(errno)); 105 } 106 } else { 107 108 int fd = result; 109 110 for (size_t remaining = size; remaining > 0;) { 111 112 RESTARTABLE(::write(fd, addr, remaining), result); 113 if (result == OS_ERR) { 114 if (PrintMiscellaneous && Verbose) { 115 warning("Could not write Perfdata save file: %s: %s\n", 116 destfile, strerror(errno)); 117 } 118 break; 119 } 120 remaining -= (size_t)result; 121 addr += result; 122 } 123 124 RESTARTABLE(::close(fd), result); 125 if (PrintMiscellaneous && Verbose) { 126 if (result == OS_ERR) { 127 warning("Could not close %s: %s\n", destfile, strerror(errno)); 128 } 129 } 130 } 131 FREE_C_HEAP_ARRAY(char, destfile); 132} 133 134 135// Shared Memory Implementation Details 136 137// Note: the solaris and linux shared memory implementation uses the mmap 138// interface with a backing store file to implement named shared memory. 139// Using the file system as the name space for shared memory allows a 140// common name space to be supported across a variety of platforms. It 141// also provides a name space that Java applications can deal with through 142// simple file apis. 143// 144// The solaris and linux implementations store the backing store file in 145// a user specific temporary directory located in the /tmp file system, 146// which is always a local file system and is sometimes a RAM based file 147// system. 148 149// return the user specific temporary directory name. 150// 151// the caller is expected to free the allocated memory. 152// 153static char* get_user_tmp_dir(const char* user) { 154 155 const char* tmpdir = os::get_temp_directory(); 156 const char* perfdir = PERFDATA_NAME; 157 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 158 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes); 159 160 // construct the path name to user specific tmp directory 161 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 162 163 return dirname; 164} 165 166// convert the given file name into a process id. if the file 167// does not meet the file naming constraints, return 0. 168// 169static pid_t filename_to_pid(const char* filename) { 170 171 // a filename that doesn't begin with a digit is not a 172 // candidate for conversion. 173 // 174 if (!isdigit(*filename)) { 175 return 0; 176 } 177 178 // check if file name can be converted to an integer without 179 // any leftover characters. 180 // 181 char* remainder = NULL; 182 errno = 0; 183 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 184 185 if (errno != 0) { 186 return 0; 187 } 188 189 // check for left over characters. If any, then the filename is 190 // not a candidate for conversion. 191 // 192 if (remainder != NULL && *remainder != '\0') { 193 return 0; 194 } 195 196 // successful conversion, return the pid 197 return pid; 198} 199 200 201// check if the given path is considered a secure directory for 202// the backing store files. Returns true if the directory exists 203// and is considered a secure location. Returns false if the path 204// is a symbolic link or if an error occurred. 205// 206static bool is_directory_secure(const char* path) { 207 struct stat statbuf; 208 int result = 0; 209 210 RESTARTABLE(::lstat(path, &statbuf), result); 211 if (result == OS_ERR) { 212 return false; 213 } 214 215 // the path exists, now check it's mode 216 if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) { 217 // the path represents a link or some non-directory file type, 218 // which is not what we expected. declare it insecure. 219 // 220 return false; 221 } 222 else { 223 // we have an existing directory, check if the permissions are safe. 224 // 225 if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) { 226 // the directory is open for writing and could be subjected 227 // to a symlnk attack. declare it insecure. 228 // 229 return false; 230 } 231 } 232 return true; 233} 234 235 236// return the user name for the given user id 237// 238// the caller is expected to free the allocated memory. 239// 240static char* get_user_name(uid_t uid) { 241 242 struct passwd pwent; 243 244 // determine the max pwbuf size from sysconf, and hardcode 245 // a default if this not available through sysconf. 246 // 247 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 248 if (bufsize == -1) 249 bufsize = 1024; 250 251 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize); 252 253#ifdef _GNU_SOURCE 254 struct passwd* p = NULL; 255 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 256#else // _GNU_SOURCE 257 struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize); 258#endif // _GNU_SOURCE 259 260 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 261 if (PrintMiscellaneous && Verbose) { 262 if (p == NULL) { 263 warning("Could not retrieve passwd entry: %s\n", 264 strerror(errno)); 265 } 266 else { 267 warning("Could not determine user name: %s\n", 268 p->pw_name == NULL ? "pw_name = NULL" : 269 "pw_name zero length"); 270 } 271 } 272 FREE_C_HEAP_ARRAY(char, pwbuf); 273 return NULL; 274 } 275 276 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1); 277 strcpy(user_name, p->pw_name); 278 279 FREE_C_HEAP_ARRAY(char, pwbuf); 280 return user_name; 281} 282 283// return the name of the user that owns the process identified by vmid. 284// 285// This method uses a slow directory search algorithm to find the backing 286// store file for the specified vmid and returns the user name, as determined 287// by the user name suffix of the hsperfdata_<username> directory name. 288// 289// the caller is expected to free the allocated memory. 290// 291static char* get_user_name_slow(int vmid, TRAPS) { 292 293 // short circuit the directory search if the process doesn't even exist. 294 if (kill(vmid, 0) == OS_ERR) { 295 if (errno == ESRCH) { 296 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 297 "Process not found"); 298 } 299 else /* EPERM */ { 300 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 301 } 302 } 303 304 // directory search 305 char* oldest_user = NULL; 306 time_t oldest_ctime = 0; 307 308 const char* tmpdirname = os::get_temp_directory(); 309 310 DIR* tmpdirp = os::opendir(tmpdirname); 311 312 if (tmpdirp == NULL) { 313 return NULL; 314 } 315 316 // for each entry in the directory that matches the pattern hsperfdata_*, 317 // open the directory and check if the file for the given vmid exists. 318 // The file with the expected name and the latest creation date is used 319 // to determine the user name for the process id. 320 // 321 struct dirent* dentry; 322 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname)); 323 errno = 0; 324 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 325 326 // check if the directory entry is a hsperfdata file 327 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 328 continue; 329 } 330 331 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 332 strlen(tmpdirname) + strlen(dentry->d_name) + 2); 333 strcpy(usrdir_name, tmpdirname); 334 strcat(usrdir_name, "/"); 335 strcat(usrdir_name, dentry->d_name); 336 337 DIR* subdirp = os::opendir(usrdir_name); 338 339 if (subdirp == NULL) { 340 FREE_C_HEAP_ARRAY(char, usrdir_name); 341 continue; 342 } 343 344 // Since we don't create the backing store files in directories 345 // pointed to by symbolic links, we also don't follow them when 346 // looking for the files. We check for a symbolic link after the 347 // call to opendir in order to eliminate a small window where the 348 // symlink can be exploited. 349 // 350 if (!is_directory_secure(usrdir_name)) { 351 FREE_C_HEAP_ARRAY(char, usrdir_name); 352 os::closedir(subdirp); 353 continue; 354 } 355 356 struct dirent* udentry; 357 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name)); 358 errno = 0; 359 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 360 361 if (filename_to_pid(udentry->d_name) == vmid) { 362 struct stat statbuf; 363 int result; 364 365 char* filename = NEW_C_HEAP_ARRAY(char, 366 strlen(usrdir_name) + strlen(udentry->d_name) + 2); 367 368 strcpy(filename, usrdir_name); 369 strcat(filename, "/"); 370 strcat(filename, udentry->d_name); 371 372 // don't follow symbolic links for the file 373 RESTARTABLE(::lstat(filename, &statbuf), result); 374 if (result == OS_ERR) { 375 FREE_C_HEAP_ARRAY(char, filename); 376 continue; 377 } 378 379 // skip over files that are not regular files. 380 if (!S_ISREG(statbuf.st_mode)) { 381 FREE_C_HEAP_ARRAY(char, filename); 382 continue; 383 } 384 385 // compare and save filename with latest creation time 386 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 387 388 if (statbuf.st_ctime > oldest_ctime) { 389 char* user = strchr(dentry->d_name, '_') + 1; 390 391 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); 392 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1); 393 394 strcpy(oldest_user, user); 395 oldest_ctime = statbuf.st_ctime; 396 } 397 } 398 399 FREE_C_HEAP_ARRAY(char, filename); 400 } 401 } 402 os::closedir(subdirp); 403 FREE_C_HEAP_ARRAY(char, udbuf); 404 FREE_C_HEAP_ARRAY(char, usrdir_name); 405 } 406 os::closedir(tmpdirp); 407 FREE_C_HEAP_ARRAY(char, tdbuf); 408 409 return(oldest_user); 410} 411 412// return the name of the user that owns the JVM indicated by the given vmid. 413// 414static char* get_user_name(int vmid, TRAPS) { 415 416 char psinfo_name[PATH_MAX]; 417 int result; 418 419 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid); 420 421 RESTARTABLE(::open(psinfo_name, O_RDONLY), result); 422 423 if (result != OS_ERR) { 424 int fd = result; 425 426 psinfo_t psinfo; 427 char* addr = (char*)&psinfo; 428 429 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) { 430 431 RESTARTABLE(::read(fd, addr, remaining), result); 432 if (result == OS_ERR) { 433 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error"); 434 } 435 remaining-=result; 436 addr+=result; 437 } 438 439 RESTARTABLE(::close(fd), result); 440 441 // get the user name for the effective user id of the process 442 char* user_name = get_user_name(psinfo.pr_euid); 443 444 return user_name; 445 } 446 447 if (result == OS_ERR && errno == EACCES) { 448 449 // In this case, the psinfo file for the process id existed, 450 // but we didn't have permission to access it. 451 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 452 strerror(errno)); 453 } 454 455 // at this point, we don't know if the process id itself doesn't 456 // exist or if the psinfo file doesn't exit. If the psinfo file 457 // doesn't exist, then we are running on Solaris 2.5.1 or earlier. 458 // since the structured procfs and old procfs interfaces can't be 459 // mixed, we attempt to find the file through a directory search. 460 461 return get_user_name_slow(vmid, CHECK_NULL); 462} 463 464// return the file name of the backing store file for the named 465// shared memory region for the given user name and vmid. 466// 467// the caller is expected to free the allocated memory. 468// 469static char* get_sharedmem_filename(const char* dirname, int vmid) { 470 471 // add 2 for the file separator and a NULL terminator. 472 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 473 474 char* name = NEW_C_HEAP_ARRAY(char, nbytes); 475 snprintf(name, nbytes, "%s/%d", dirname, vmid); 476 477 return name; 478} 479 480 481// remove file 482// 483// this method removes the file specified by the given path 484// 485static void remove_file(const char* path) { 486 487 int result; 488 489 // if the file is a directory, the following unlink will fail. since 490 // we don't expect to find directories in the user temp directory, we 491 // won't try to handle this situation. even if accidentially or 492 // maliciously planted, the directory's presence won't hurt anything. 493 // 494 RESTARTABLE(::unlink(path), result); 495 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 496 if (errno != ENOENT) { 497 warning("Could not unlink shared memory backing" 498 " store file %s : %s\n", path, strerror(errno)); 499 } 500 } 501} 502 503 504// remove file 505// 506// this method removes the file with the given file name in the 507// named directory. 508// 509static void remove_file(const char* dirname, const char* filename) { 510 511 size_t nbytes = strlen(dirname) + strlen(filename) + 2; 512 char* path = NEW_C_HEAP_ARRAY(char, nbytes); 513 514 strcpy(path, dirname); 515 strcat(path, "/"); 516 strcat(path, filename); 517 518 remove_file(path); 519 520 FREE_C_HEAP_ARRAY(char, path); 521} 522 523 524// cleanup stale shared memory resources 525// 526// This method attempts to remove all stale shared memory files in 527// the named user temporary directory. It scans the named directory 528// for files matching the pattern ^$[0-9]*$. For each file found, the 529// process id is extracted from the file name and a test is run to 530// determine if the process is alive. If the process is not alive, 531// any stale file resources are removed. 532// 533static void cleanup_sharedmem_resources(const char* dirname) { 534 535 // open the user temp directory 536 DIR* dirp = os::opendir(dirname); 537 538 if (dirp == NULL) { 539 // directory doesn't exist, so there is nothing to cleanup 540 return; 541 } 542 543 if (!is_directory_secure(dirname)) { 544 // the directory is not a secure directory 545 return; 546 } 547 548 // for each entry in the directory that matches the expected file 549 // name pattern, determine if the file resources are stale and if 550 // so, remove the file resources. Note, instrumented HotSpot processes 551 // for this user may start and/or terminate during this search and 552 // remove or create new files in this directory. The behavior of this 553 // loop under these conditions is dependent upon the implementation of 554 // opendir/readdir. 555 // 556 struct dirent* entry; 557 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname)); 558 errno = 0; 559 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 560 561 pid_t pid = filename_to_pid(entry->d_name); 562 563 if (pid == 0) { 564 565 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 566 567 // attempt to remove all unexpected files, except "." and ".." 568 remove_file(dirname, entry->d_name); 569 } 570 571 errno = 0; 572 continue; 573 } 574 575 // we now have a file name that converts to a valid integer 576 // that could represent a process id . if this process id 577 // matches the current process id or the process is not running, 578 // then remove the stale file resources. 579 // 580 // process liveness is detected by sending signal number 0 to 581 // the process id (see kill(2)). if kill determines that the 582 // process does not exist, then the file resources are removed. 583 // if kill determines that that we don't have permission to 584 // signal the process, then the file resources are assumed to 585 // be stale and are removed because the resources for such a 586 // process should be in a different user specific directory. 587 // 588 if ((pid == os::current_process_id()) || 589 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 590 591 remove_file(dirname, entry->d_name); 592 } 593 errno = 0; 594 } 595 os::closedir(dirp); 596 FREE_C_HEAP_ARRAY(char, dbuf); 597} 598 599// make the user specific temporary directory. Returns true if 600// the directory exists and is secure upon return. Returns false 601// if the directory exists but is either a symlink, is otherwise 602// insecure, or if an error occurred. 603// 604static bool make_user_tmp_dir(const char* dirname) { 605 606 // create the directory with 0755 permissions. note that the directory 607 // will be owned by euid::egid, which may not be the same as uid::gid. 608 // 609 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 610 if (errno == EEXIST) { 611 // The directory already exists and was probably created by another 612 // JVM instance. However, this could also be the result of a 613 // deliberate symlink. Verify that the existing directory is safe. 614 // 615 if (!is_directory_secure(dirname)) { 616 // directory is not secure 617 if (PrintMiscellaneous && Verbose) { 618 warning("%s directory is insecure\n", dirname); 619 } 620 return false; 621 } 622 } 623 else { 624 // we encountered some other failure while attempting 625 // to create the directory 626 // 627 if (PrintMiscellaneous && Verbose) { 628 warning("could not create directory %s: %s\n", 629 dirname, strerror(errno)); 630 } 631 return false; 632 } 633 } 634 return true; 635} 636 637// create the shared memory file resources 638// 639// This method creates the shared memory file with the given size 640// This method also creates the user specific temporary directory, if 641// it does not yet exist. 642// 643static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 644 645 // make the user temporary directory 646 if (!make_user_tmp_dir(dirname)) { 647 // could not make/find the directory or the found directory 648 // was not secure 649 return -1; 650 } 651 652 int result; 653 654 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result); 655 if (result == OS_ERR) { 656 if (PrintMiscellaneous && Verbose) { 657 warning("could not create file %s: %s\n", filename, strerror(errno)); 658 } 659 return -1; 660 } 661 662 // save the file descriptor 663 int fd = result; 664 665 // set the file size 666 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 667 if (result == OS_ERR) { 668 if (PrintMiscellaneous && Verbose) { 669 warning("could not set shared memory file size: %s\n", strerror(errno)); 670 } 671 RESTARTABLE(::close(fd), result); 672 return -1; 673 } 674 675 return fd; 676} 677 678// open the shared memory file for the given user and vmid. returns 679// the file descriptor for the open file or -1 if the file could not 680// be opened. 681// 682static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 683 684 // open the file 685 int result; 686 RESTARTABLE(::open(filename, oflags), result); 687 if (result == OS_ERR) { 688 if (errno == ENOENT) { 689 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 690 "Process not found"); 691 } 692 else if (errno == EACCES) { 693 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 694 "Permission denied"); 695 } 696 else { 697 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 698 } 699 } 700 701 return result; 702} 703 704// create a named shared memory region. returns the address of the 705// memory region on success or NULL on failure. A return value of 706// NULL will ultimately disable the shared memory feature. 707// 708// On Solaris and Linux, the name space for shared memory objects 709// is the file system name space. 710// 711// A monitoring application attaching to a JVM does not need to know 712// the file system name of the shared memory object. However, it may 713// be convenient for applications to discover the existence of newly 714// created and terminating JVMs by watching the file system name space 715// for files being created or removed. 716// 717static char* mmap_create_shared(size_t size) { 718 719 int result; 720 int fd; 721 char* mapAddress; 722 723 int vmid = os::current_process_id(); 724 725 char* user_name = get_user_name(geteuid()); 726 727 if (user_name == NULL) 728 return NULL; 729 730 char* dirname = get_user_tmp_dir(user_name); 731 char* filename = get_sharedmem_filename(dirname, vmid); 732 733 // cleanup any stale shared memory files 734 cleanup_sharedmem_resources(dirname); 735 736 assert(((size > 0) && (size % os::vm_page_size() == 0)), 737 "unexpected PerfMemory region size"); 738 739 fd = create_sharedmem_resources(dirname, filename, size); 740 741 FREE_C_HEAP_ARRAY(char, user_name); 742 FREE_C_HEAP_ARRAY(char, dirname); 743 744 if (fd == -1) { 745 FREE_C_HEAP_ARRAY(char, filename); 746 return NULL; 747 } 748 749 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 750 751 // attempt to close the file - restart it if it was interrupted, 752 // but ignore other failures 753 RESTARTABLE(::close(fd), result); 754 assert(result != OS_ERR, "could not close file"); 755 756 if (mapAddress == MAP_FAILED) { 757 if (PrintMiscellaneous && Verbose) { 758 warning("mmap failed - %s\n", strerror(errno)); 759 } 760 remove_file(filename); 761 FREE_C_HEAP_ARRAY(char, filename); 762 return NULL; 763 } 764 765 // save the file name for use in delete_shared_memory() 766 backing_store_file_name = filename; 767 768 // clear the shared memory region 769 (void)::memset((void*) mapAddress, 0, size); 770 771 return mapAddress; 772} 773 774// release a named shared memory region 775// 776static void unmap_shared(char* addr, size_t bytes) { 777 os::release_memory(addr, bytes); 778} 779 780// create the PerfData memory region in shared memory. 781// 782static char* create_shared_memory(size_t size) { 783 784 // create the shared memory region. 785 return mmap_create_shared(size); 786} 787 788// delete the shared PerfData memory region 789// 790static void delete_shared_memory(char* addr, size_t size) { 791 792 // cleanup the persistent shared memory resources. since DestroyJavaVM does 793 // not support unloading of the JVM, unmapping of the memory resource is 794 // not performed. The memory will be reclaimed by the OS upon termination of 795 // the process. The backing store file is deleted from the file system. 796 797 assert(!PerfDisableSharedMem, "shouldn't be here"); 798 799 if (backing_store_file_name != NULL) { 800 remove_file(backing_store_file_name); 801 // Don't.. Free heap memory could deadlock os::abort() if it is called 802 // from signal handler. OS will reclaim the heap memory. 803 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 804 backing_store_file_name = NULL; 805 } 806} 807 808// return the size of the file for the given file descriptor 809// or 0 if it is not a valid size for a shared memory file 810// 811static size_t sharedmem_filesize(int fd, TRAPS) { 812 813 struct stat statbuf; 814 int result; 815 816 RESTARTABLE(::fstat(fd, &statbuf), result); 817 if (result == OS_ERR) { 818 if (PrintMiscellaneous && Verbose) { 819 warning("fstat failed: %s\n", strerror(errno)); 820 } 821 THROW_MSG_0(vmSymbols::java_io_IOException(), 822 "Could not determine PerfMemory size"); 823 } 824 825 if ((statbuf.st_size == 0) || 826 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 827 THROW_MSG_0(vmSymbols::java_lang_Exception(), 828 "Invalid PerfMemory size"); 829 } 830 831 return (size_t)statbuf.st_size; 832} 833 834// attach to a named shared memory region. 835// 836static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 837 838 char* mapAddress; 839 int result; 840 int fd; 841 size_t size; 842 const char* luser = NULL; 843 844 int mmap_prot; 845 int file_flags; 846 847 ResourceMark rm; 848 849 // map the high level access mode to the appropriate permission 850 // constructs for the file and the shared memory mapping. 851 if (mode == PerfMemory::PERF_MODE_RO) { 852 mmap_prot = PROT_READ; 853 file_flags = O_RDONLY; 854 } 855 else if (mode == PerfMemory::PERF_MODE_RW) { 856#ifdef LATER 857 mmap_prot = PROT_READ | PROT_WRITE; 858 file_flags = O_RDWR; 859#else 860 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 861 "Unsupported access mode"); 862#endif 863 } 864 else { 865 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 866 "Illegal access mode"); 867 } 868 869 if (user == NULL || strlen(user) == 0) { 870 luser = get_user_name(vmid, CHECK); 871 } 872 else { 873 luser = user; 874 } 875 876 if (luser == NULL) { 877 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 878 "Could not map vmid to user Name"); 879 } 880 881 char* dirname = get_user_tmp_dir(luser); 882 883 // since we don't follow symbolic links when creating the backing 884 // store file, we don't follow them when attaching either. 885 // 886 if (!is_directory_secure(dirname)) { 887 FREE_C_HEAP_ARRAY(char, dirname); 888 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 889 "Process not found"); 890 } 891 892 char* filename = get_sharedmem_filename(dirname, vmid); 893 894 // copy heap memory to resource memory. the open_sharedmem_file 895 // method below need to use the filename, but could throw an 896 // exception. using a resource array prevents the leak that 897 // would otherwise occur. 898 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 899 strcpy(rfilename, filename); 900 901 // free the c heap resources that are no longer needed 902 if (luser != user) FREE_C_HEAP_ARRAY(char, luser); 903 FREE_C_HEAP_ARRAY(char, dirname); 904 FREE_C_HEAP_ARRAY(char, filename); 905 906 // open the shared memory file for the give vmid 907 fd = open_sharedmem_file(rfilename, file_flags, CHECK); 908 assert(fd != OS_ERR, "unexpected value"); 909 910 if (*sizep == 0) { 911 size = sharedmem_filesize(fd, CHECK); 912 assert(size != 0, "unexpected size"); 913 } 914 915 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 916 917 // attempt to close the file - restart if it gets interrupted, 918 // but ignore other failures 919 RESTARTABLE(::close(fd), result); 920 assert(result != OS_ERR, "could not close file"); 921 922 if (mapAddress == MAP_FAILED) { 923 if (PrintMiscellaneous && Verbose) { 924 warning("mmap failed: %s\n", strerror(errno)); 925 } 926 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 927 "Could not map PerfMemory"); 928 } 929 930 *addr = mapAddress; 931 *sizep = size; 932 933 if (PerfTraceMemOps) { 934 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 935 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress); 936 } 937} 938 939 940 941 942// create the PerfData memory region 943// 944// This method creates the memory region used to store performance 945// data for the JVM. The memory may be created in standard or 946// shared memory. 947// 948void PerfMemory::create_memory_region(size_t size) { 949 950 if (PerfDisableSharedMem) { 951 // do not share the memory for the performance data. 952 _start = create_standard_memory(size); 953 } 954 else { 955 _start = create_shared_memory(size); 956 if (_start == NULL) { 957 958 // creation of the shared memory region failed, attempt 959 // to create a contiguous, non-shared memory region instead. 960 // 961 if (PrintMiscellaneous && Verbose) { 962 warning("Reverting to non-shared PerfMemory region.\n"); 963 } 964 PerfDisableSharedMem = true; 965 _start = create_standard_memory(size); 966 } 967 } 968 969 if (_start != NULL) _capacity = size; 970 971} 972 973// delete the PerfData memory region 974// 975// This method deletes the memory region used to store performance 976// data for the JVM. The memory region indicated by the <address, size> 977// tuple will be inaccessible after a call to this method. 978// 979void PerfMemory::delete_memory_region() { 980 981 assert((start() != NULL && capacity() > 0), "verify proper state"); 982 983 // If user specifies PerfDataSaveFile, it will save the performance data 984 // to the specified file name no matter whether PerfDataSaveToFile is specified 985 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 986 // -XX:+PerfDataSaveToFile. 987 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 988 save_memory_to_file(start(), capacity()); 989 } 990 991 if (PerfDisableSharedMem) { 992 delete_standard_memory(start(), capacity()); 993 } 994 else { 995 delete_shared_memory(start(), capacity()); 996 } 997} 998 999// attach to the PerfData memory region for another JVM 1000// 1001// This method returns an <address, size> tuple that points to 1002// a memory buffer that is kept reasonably synchronized with 1003// the PerfData memory region for the indicated JVM. This 1004// buffer may be kept in synchronization via shared memory 1005// or some other mechanism that keeps the buffer updated. 1006// 1007// If the JVM chooses not to support the attachability feature, 1008// this method should throw an UnsupportedOperation exception. 1009// 1010// This implementation utilizes named shared memory to map 1011// the indicated process's PerfData memory region into this JVMs 1012// address space. 1013// 1014void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1015 1016 if (vmid == 0 || vmid == os::current_process_id()) { 1017 *addrp = start(); 1018 *sizep = capacity(); 1019 return; 1020 } 1021 1022 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1023} 1024 1025// detach from the PerfData memory region of another JVM 1026// 1027// This method detaches the PerfData memory region of another 1028// JVM, specified as an <address, size> tuple of a buffer 1029// in this process's address space. This method may perform 1030// arbitrary actions to accomplish the detachment. The memory 1031// region specified by <address, size> will be inaccessible after 1032// a call to this method. 1033// 1034// If the JVM chooses not to support the attachability feature, 1035// this method should throw an UnsupportedOperation exception. 1036// 1037// This implementation utilizes named shared memory to detach 1038// the indicated process's PerfData memory region from this 1039// process's address space. 1040// 1041void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1042 1043 assert(addr != 0, "address sanity check"); 1044 assert(bytes > 0, "capacity sanity check"); 1045 1046 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1047 // prevent accidental detachment of this process's PerfMemory region 1048 return; 1049 } 1050 1051 unmap_shared(addr, bytes); 1052} 1053 1054char* PerfMemory::backing_store_filename() { 1055 return backing_store_file_name; 1056} 1057