1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * Copyright 2012, 2013 SAP AG. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "os_aix.inline.hpp"
32 #include "runtime/handles.inline.hpp"
33 #include "runtime/perfMemory.hpp"
34 #include "utilities/exceptions.hpp"
35
36 // put OS-includes here
37 # include <sys/types.h>
38 # include <sys/mman.h>
39 # include <errno.h>
40 # include <stdio.h>
41 # include <unistd.h>
42 # include <sys/stat.h>
43 # include <signal.h>
44 # include <pwd.h>
45
46 static char* backing_store_file_name = NULL; // name of the backing store
47 // file, if successfully created.
48
49 // Standard Memory Implementation Details
50
51 // create the PerfData memory region in standard memory.
52 //
53 static char* create_standard_memory(size_t size) {
54
55 // allocate an aligned chuck of memory
56 char* mapAddress = os::reserve_memory(size);
57
58 if (mapAddress == NULL) {
59 return NULL;
60 }
61
62 // commit memory
63 if (!os::commit_memory(mapAddress, size, !ExecMem)) {
64 if (PrintMiscellaneous && Verbose) {
65 warning("Could not commit PerfData memory\n");
66 }
67 os::release_memory(mapAddress, size);
68 return NULL;
69 }
70
71 return mapAddress;
72 }
73
74 // delete the PerfData memory region
75 //
76 static void delete_standard_memory(char* addr, size_t size) {
77
78 // there are no persistent external resources to cleanup for standard
79 // memory. since DestroyJavaVM does not support unloading of the JVM,
80 // cleanup of the memory resource is not performed. The memory will be
81 // reclaimed by the OS upon termination of the process.
82 //
83 return;
84 }
85
86 // save the specified memory region to the given file
87 //
88 // Note: this function might be called from signal handler (by os::abort()),
89 // don't allocate heap memory.
90 //
91 static void save_memory_to_file(char* addr, size_t size) {
92
93 const char* destfile = PerfMemory::get_perfdata_file_path();
94 assert(destfile[0] != '\0', "invalid PerfData file path");
95
96 int result;
97
98 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
99 result);;
100 if (result == OS_ERR) {
101 if (PrintMiscellaneous && Verbose) {
102 warning("Could not create Perfdata save file: %s: %s\n",
103 destfile, strerror(errno));
104 }
105 } else {
106 int fd = result;
107
108 for (size_t remaining = size; remaining > 0;) {
109
110 RESTARTABLE(::write(fd, addr, remaining), result);
111 if (result == OS_ERR) {
112 if (PrintMiscellaneous && Verbose) {
113 warning("Could not write Perfdata save file: %s: %s\n",
114 destfile, strerror(errno));
115 }
116 break;
117 }
118
119 remaining -= (size_t)result;
120 addr += result;
121 }
122
123 RESTARTABLE(::close(fd), result);
124 if (PrintMiscellaneous && Verbose) {
125 if (result == OS_ERR) {
126 warning("Could not close %s: %s\n", destfile, strerror(errno));
127 }
128 }
129 }
130 FREE_C_HEAP_ARRAY(char, destfile);
131 }
132
133
134 // Shared Memory Implementation Details
135
136 // Note: the solaris and linux shared memory implementation uses the mmap
137 // interface with a backing store file to implement named shared memory.
138 // Using the file system as the name space for shared memory allows a
139 // common name space to be supported across a variety of platforms. It
140 // also provides a name space that Java applications can deal with through
141 // simple file apis.
142 //
143 // The solaris and linux implementations store the backing store file in
144 // a user specific temporary directory located in the /tmp file system,
145 // which is always a local file system and is sometimes a RAM based file
146 // system.
147
148 // return the user specific temporary directory name.
149 //
150 // the caller is expected to free the allocated memory.
151 //
152 static char* get_user_tmp_dir(const char* user) {
153
154 const char* tmpdir = os::get_temp_directory();
155 const char* perfdir = PERFDATA_NAME;
156 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3;
157 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
158
159 // construct the path name to user specific tmp directory
160 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
161
162 return dirname;
163 }
164
165 // convert the given file name into a process id. if the file
166 // does not meet the file naming constraints, return 0.
167 //
168 static pid_t filename_to_pid(const char* filename) {
169
170 // a filename that doesn't begin with a digit is not a
171 // candidate for conversion.
172 //
173 if (!isdigit(*filename)) {
174 return 0;
175 }
176
177 // check if file name can be converted to an integer without
178 // any leftover characters.
179 //
180 char* remainder = NULL;
181 errno = 0;
182 pid_t pid = (pid_t)strtol(filename, &remainder, 10);
183
184 if (errno != 0) {
185 return 0;
186 }
187
188 // check for left over characters. If any, then the filename is
189 // not a candidate for conversion.
190 //
191 if (remainder != NULL && *remainder != '\0') {
192 return 0;
193 }
194
195 // successful conversion, return the pid
196 return pid;
197 }
198
199
200 // check if the given path is considered a secure directory for
201 // the backing store files. Returns true if the directory exists
202 // and is considered a secure location. Returns false if the path
203 // is a symbolic link or if an error occurred.
204 //
205 static bool is_directory_secure(const char* path) {
206 struct stat statbuf;
207 int result = 0;
208
209 RESTARTABLE(::lstat(path, &statbuf), result);
210 if (result == OS_ERR) {
211 return false;
212 }
213
214 // the path exists, now check it's mode
215 if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) {
216 // the path represents a link or some non-directory file type,
217 // which is not what we expected. declare it insecure.
218 //
219 return false;
220 }
221 else {
222 // we have an existing directory, check if the permissions are safe.
223 //
224 if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
225 // the directory is open for writing and could be subjected
226 // to a symlnk attack. declare it insecure.
227 //
228 return false;
229 }
230 }
231 return true;
232 }
233
234
235 // return the user name for the given user id
236 //
237 // the caller is expected to free the allocated memory.
238 //
239 static char* get_user_name(uid_t uid) {
240
241 struct passwd pwent;
242
243 // determine the max pwbuf size from sysconf, and hardcode
244 // a default if this not available through sysconf.
245 //
246 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
247 if (bufsize == -1)
248 bufsize = 1024;
249
250 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
251
252 // POSIX interface to getpwuid_r is used on LINUX
253 struct passwd* p;
254 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
255
256 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
257 if (PrintMiscellaneous && Verbose) {
258 if (result != 0) {
259 warning("Could not retrieve passwd entry: %s\n",
260 strerror(result));
261 }
262 else if (p == NULL) {
263 // this check is added to protect against an observed problem
264 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0,
265 // indicating success, but has p == NULL. This was observed when
266 // inserting a file descriptor exhaustion fault prior to the call
267 // getpwuid_r() call. In this case, error is set to the appropriate
268 // error condition, but this is undocumented behavior. This check
269 // is safe under any condition, but the use of errno in the output
270 // message may result in an erroneous message.
271 // Bug Id 89052 was opened with RedHat.
272 //
273 warning("Could not retrieve passwd entry: %s\n",
274 strerror(errno));
275 }
276 else {
277 warning("Could not determine user name: %s\n",
278 p->pw_name == NULL ? "pw_name = NULL" :
279 "pw_name zero length");
280 }
281 }
282 FREE_C_HEAP_ARRAY(char, pwbuf);
283 return NULL;
284 }
285
286 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
287 strcpy(user_name, p->pw_name);
288
289 FREE_C_HEAP_ARRAY(char, pwbuf);
290 return user_name;
291 }
292
293 // return the name of the user that owns the process identified by vmid.
294 //
295 // This method uses a slow directory search algorithm to find the backing
296 // store file for the specified vmid and returns the user name, as determined
297 // by the user name suffix of the hsperfdata_<username> directory name.
298 //
299 // the caller is expected to free the allocated memory.
300 //
301 static char* get_user_name_slow(int vmid, TRAPS) {
302
303 // short circuit the directory search if the process doesn't even exist.
304 if (kill(vmid, 0) == OS_ERR) {
305 if (errno == ESRCH) {
306 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
307 "Process not found");
308 }
309 else /* EPERM */ {
310 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
311 }
312 }
313
314 // directory search
315 char* oldest_user = NULL;
316 time_t oldest_ctime = 0;
317
318 const char* tmpdirname = os::get_temp_directory();
319
320 DIR* tmpdirp = os::opendir(tmpdirname);
321
322 if (tmpdirp == NULL) {
323 return NULL;
324 }
325
326 // for each entry in the directory that matches the pattern hsperfdata_*,
327 // open the directory and check if the file for the given vmid exists.
328 // The file with the expected name and the latest creation date is used
329 // to determine the user name for the process id.
330 //
331 struct dirent* dentry;
332 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
333 errno = 0;
334 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
335
336 // check if the directory entry is a hsperfdata file
337 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
338 continue;
339 }
340
341 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
342 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
343 strcpy(usrdir_name, tmpdirname);
344 strcat(usrdir_name, "/");
345 strcat(usrdir_name, dentry->d_name);
346
347 DIR* subdirp = os::opendir(usrdir_name);
348
349 if (subdirp == NULL) {
350 FREE_C_HEAP_ARRAY(char, usrdir_name);
351 continue;
352 }
353
354 // Since we don't create the backing store files in directories
355 // pointed to by symbolic links, we also don't follow them when
356 // looking for the files. We check for a symbolic link after the
357 // call to opendir in order to eliminate a small window where the
358 // symlink can be exploited.
359 //
360 if (!is_directory_secure(usrdir_name)) {
361 FREE_C_HEAP_ARRAY(char, usrdir_name);
362 os::closedir(subdirp);
363 continue;
364 }
365
366 struct dirent* udentry;
367 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
368 errno = 0;
369 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
370
371 if (filename_to_pid(udentry->d_name) == vmid) {
372 struct stat statbuf;
373 int result;
374
375 char* filename = NEW_C_HEAP_ARRAY(char,
376 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
377
378 strcpy(filename, usrdir_name);
379 strcat(filename, "/");
380 strcat(filename, udentry->d_name);
381
382 // don't follow symbolic links for the file
383 RESTARTABLE(::lstat(filename, &statbuf), result);
384 if (result == OS_ERR) {
385 FREE_C_HEAP_ARRAY(char, filename);
386 continue;
387 }
388
389 // skip over files that are not regular files.
390 if (!S_ISREG(statbuf.st_mode)) {
391 FREE_C_HEAP_ARRAY(char, filename);
392 continue;
393 }
394
395 // compare and save filename with latest creation time
396 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
397
398 if (statbuf.st_ctime > oldest_ctime) {
399 char* user = strchr(dentry->d_name, '_') + 1;
400
401 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
402 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
403
404 strcpy(oldest_user, user);
405 oldest_ctime = statbuf.st_ctime;
406 }
407 }
408
409 FREE_C_HEAP_ARRAY(char, filename);
410 }
411 }
412 os::closedir(subdirp);
413 FREE_C_HEAP_ARRAY(char, udbuf);
414 FREE_C_HEAP_ARRAY(char, usrdir_name);
415 }
416 os::closedir(tmpdirp);
417 FREE_C_HEAP_ARRAY(char, tdbuf);
418
419 return(oldest_user);
420 }
421
422 // return the name of the user that owns the JVM indicated by the given vmid.
423 //
424 static char* get_user_name(int vmid, TRAPS) {
425 return get_user_name_slow(vmid, THREAD);
426 }
427
428 // return the file name of the backing store file for the named
429 // shared memory region for the given user name and vmid.
430 //
431 // the caller is expected to free the allocated memory.
432 //
433 static char* get_sharedmem_filename(const char* dirname, int vmid) {
434
435 // add 2 for the file separator and a null terminator.
436 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
437
438 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
439 snprintf(name, nbytes, "%s/%d", dirname, vmid);
440
441 return name;
442 }
443
444
445 // remove file
446 //
447 // this method removes the file specified by the given path
448 //
449 static void remove_file(const char* path) {
450
451 int result;
452
453 // if the file is a directory, the following unlink will fail. since
454 // we don't expect to find directories in the user temp directory, we
455 // won't try to handle this situation. even if accidentially or
456 // maliciously planted, the directory's presence won't hurt anything.
457 //
458 RESTARTABLE(::unlink(path), result);
459 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
460 if (errno != ENOENT) {
461 warning("Could not unlink shared memory backing"
462 " store file %s : %s\n", path, strerror(errno));
463 }
464 }
465 }
466
467
468 // remove file
469 //
470 // this method removes the file with the given file name in the
471 // named directory.
472 //
473 static void remove_file(const char* dirname, const char* filename) {
474
475 size_t nbytes = strlen(dirname) + strlen(filename) + 2;
476 char* path = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
477
478 strcpy(path, dirname);
479 strcat(path, "/");
480 strcat(path, filename);
481
482 remove_file(path);
483
484 FREE_C_HEAP_ARRAY(char, path);
485 }
486
487
488 // cleanup stale shared memory resources
489 //
490 // This method attempts to remove all stale shared memory files in
491 // the named user temporary directory. It scans the named directory
492 // for files matching the pattern ^$[0-9]*$. For each file found, the
493 // process id is extracted from the file name and a test is run to
494 // determine if the process is alive. If the process is not alive,
495 // any stale file resources are removed.
496 //
497 static void cleanup_sharedmem_resources(const char* dirname) {
498
499 // open the user temp directory
500 DIR* dirp = os::opendir(dirname);
501
502 if (dirp == NULL) {
503 // directory doesn't exist, so there is nothing to cleanup
504 return;
505 }
506
507 if (!is_directory_secure(dirname)) {
508 // the directory is not a secure directory
509 os::closedir(dirp);
510 return;
511 }
512
513 // for each entry in the directory that matches the expected file
514 // name pattern, determine if the file resources are stale and if
515 // so, remove the file resources. Note, instrumented HotSpot processes
516 // for this user may start and/or terminate during this search and
517 // remove or create new files in this directory. The behavior of this
518 // loop under these conditions is dependent upon the implementation of
519 // opendir/readdir.
520 //
521 struct dirent* entry;
522 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
523 errno = 0;
524 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
525
526 pid_t pid = filename_to_pid(entry->d_name);
527
528 if (pid == 0) {
529
530 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
531
532 // attempt to remove all unexpected files, except "." and ".."
533 remove_file(dirname, entry->d_name);
534 }
535
536 errno = 0;
537 continue;
538 }
539
540 // we now have a file name that converts to a valid integer
541 // that could represent a process id . if this process id
542 // matches the current process id or the process is not running,
543 // then remove the stale file resources.
544 //
545 // process liveness is detected by sending signal number 0 to
546 // the process id (see kill(2)). if kill determines that the
547 // process does not exist, then the file resources are removed.
548 // if kill determines that that we don't have permission to
549 // signal the process, then the file resources are assumed to
550 // be stale and are removed because the resources for such a
551 // process should be in a different user specific directory.
552 //
553 if ((pid == os::current_process_id()) ||
554 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
555
556 remove_file(dirname, entry->d_name);
557 }
558 errno = 0;
559 }
560 os::closedir(dirp);
561 FREE_C_HEAP_ARRAY(char, dbuf);
562 }
563
564 // make the user specific temporary directory. Returns true if
565 // the directory exists and is secure upon return. Returns false
566 // if the directory exists but is either a symlink, is otherwise
567 // insecure, or if an error occurred.
568 //
569 static bool make_user_tmp_dir(const char* dirname) {
570
571 // create the directory with 0755 permissions. note that the directory
572 // will be owned by euid::egid, which may not be the same as uid::gid.
573 //
574 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
575 if (errno == EEXIST) {
576 // The directory already exists and was probably created by another
577 // JVM instance. However, this could also be the result of a
578 // deliberate symlink. Verify that the existing directory is safe.
579 //
580 if (!is_directory_secure(dirname)) {
581 // directory is not secure
582 if (PrintMiscellaneous && Verbose) {
583 warning("%s directory is insecure\n", dirname);
584 }
585 return false;
586 }
587 }
588 else {
589 // we encountered some other failure while attempting
590 // to create the directory
591 //
592 if (PrintMiscellaneous && Verbose) {
593 warning("could not create directory %s: %s\n",
594 dirname, strerror(errno));
595 }
596 return false;
597 }
598 }
599 return true;
600 }
601
602 // create the shared memory file resources
603 //
604 // This method creates the shared memory file with the given size
605 // This method also creates the user specific temporary directory, if
606 // it does not yet exist.
607 //
608 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
609
610 // make the user temporary directory
611 if (!make_user_tmp_dir(dirname)) {
612 // could not make/find the directory or the found directory
613 // was not secure
614 return -1;
615 }
616
617 int result;
618
619 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result);
620 if (result == OS_ERR) {
621 if (PrintMiscellaneous && Verbose) {
622 warning("could not create file %s: %s\n", filename, strerror(errno));
623 }
624 return -1;
625 }
626
627 // save the file descriptor
628 int fd = result;
629
630 // set the file size
631 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
632 if (result == OS_ERR) {
633 if (PrintMiscellaneous && Verbose) {
634 warning("could not set shared memory file size: %s\n", strerror(errno));
635 }
636 RESTARTABLE(::close(fd), result);
637 return -1;
638 }
639
640 return fd;
641 }
642
643 // open the shared memory file for the given user and vmid. returns
644 // the file descriptor for the open file or -1 if the file could not
645 // be opened.
646 //
647 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
648
649 // open the file
650 int result;
651 RESTARTABLE(::open(filename, oflags), result);
652 if (result == OS_ERR) {
653 if (errno == ENOENT) {
654 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
655 "Process not found");
656 }
657 else if (errno == EACCES) {
658 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
659 "Permission denied");
660 }
661 else {
662 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
663 }
664 }
665
666 return result;
667 }
668
669 // create a named shared memory region. returns the address of the
670 // memory region on success or NULL on failure. A return value of
671 // NULL will ultimately disable the shared memory feature.
672 //
673 // On Solaris and Linux, the name space for shared memory objects
674 // is the file system name space.
675 //
676 // A monitoring application attaching to a JVM does not need to know
677 // the file system name of the shared memory object. However, it may
678 // be convenient for applications to discover the existence of newly
679 // created and terminating JVMs by watching the file system name space
680 // for files being created or removed.
681 //
682 static char* mmap_create_shared(size_t size) {
683
684 int result;
685 int fd;
686 char* mapAddress;
687
688 int vmid = os::current_process_id();
689
690 char* user_name = get_user_name(geteuid());
691
692 if (user_name == NULL)
693 return NULL;
694
695 char* dirname = get_user_tmp_dir(user_name);
696 char* filename = get_sharedmem_filename(dirname, vmid);
697
698 // cleanup any stale shared memory files
699 cleanup_sharedmem_resources(dirname);
700
701 assert(((size > 0) && (size % os::vm_page_size() == 0)),
702 "unexpected PerfMemory region size");
703
704 fd = create_sharedmem_resources(dirname, filename, size);
705
706 FREE_C_HEAP_ARRAY(char, user_name);
707 FREE_C_HEAP_ARRAY(char, dirname);
708
709 if (fd == -1) {
710 FREE_C_HEAP_ARRAY(char, filename);
711 return NULL;
712 }
713
714 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
715
716 // attempt to close the file - restart it if it was interrupted,
717 // but ignore other failures
718 RESTARTABLE(::close(fd), result);
719 assert(result != OS_ERR, "could not close file");
720
721 if (mapAddress == MAP_FAILED) {
722 if (PrintMiscellaneous && Verbose) {
723 warning("mmap failed - %s\n", strerror(errno));
724 }
725 remove_file(filename);
726 FREE_C_HEAP_ARRAY(char, filename);
727 return NULL;
728 }
729
730 // save the file name for use in delete_shared_memory()
731 backing_store_file_name = filename;
732
733 // clear the shared memory region
734 (void)::memset((void*) mapAddress, 0, size);
735
736 return mapAddress;
737 }
738
739 // release a named shared memory region
740 //
741 static void unmap_shared(char* addr, size_t bytes) {
742 // Do not rely on os::reserve_memory/os::release_memory to use mmap.
743 // Use os::reserve_memory/os::release_memory for PerfDisableSharedMem=1, mmap/munmap for PerfDisableSharedMem=0
744 if (::munmap(addr, bytes) == -1) {
745 warning("perfmemory: munmap failed (%d)\n", errno);
746 }
747 }
748
749 // create the PerfData memory region in shared memory.
750 //
751 static char* create_shared_memory(size_t size) {
752
753 // create the shared memory region.
754 return mmap_create_shared(size);
755 }
756
757 // delete the shared PerfData memory region
758 //
759 static void delete_shared_memory(char* addr, size_t size) {
760
761 // cleanup the persistent shared memory resources. since DestroyJavaVM does
762 // not support unloading of the JVM, unmapping of the memory resource is
763 // not performed. The memory will be reclaimed by the OS upon termination of
764 // the process. The backing store file is deleted from the file system.
765
766 assert(!PerfDisableSharedMem, "shouldn't be here");
767
768 if (backing_store_file_name != NULL) {
769 remove_file(backing_store_file_name);
770 // Don't.. Free heap memory could deadlock os::abort() if it is called
771 // from signal handler. OS will reclaim the heap memory.
772 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
773 backing_store_file_name = NULL;
774 }
775 }
776
777 // return the size of the file for the given file descriptor
778 // or 0 if it is not a valid size for a shared memory file
779 //
780 static size_t sharedmem_filesize(int fd, TRAPS) {
781
782 struct stat statbuf;
783 int result;
784
785 RESTARTABLE(::fstat(fd, &statbuf), result);
786 if (result == OS_ERR) {
787 if (PrintMiscellaneous && Verbose) {
788 warning("fstat failed: %s\n", strerror(errno));
789 }
790 THROW_MSG_0(vmSymbols::java_io_IOException(),
791 "Could not determine PerfMemory size");
792 }
793
794 if ((statbuf.st_size == 0) ||
795 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
796 THROW_MSG_0(vmSymbols::java_lang_Exception(),
797 "Invalid PerfMemory size");
798 }
799
800 return (size_t)statbuf.st_size;
801 }
802
803 // attach to a named shared memory region.
804 //
805 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
806
807 char* mapAddress;
808 int result;
809 int fd;
810 size_t size;
811 const char* luser = NULL;
812
813 int mmap_prot;
814 int file_flags;
815
816 ResourceMark rm;
817
818 // map the high level access mode to the appropriate permission
819 // constructs for the file and the shared memory mapping.
820 if (mode == PerfMemory::PERF_MODE_RO) {
821 mmap_prot = PROT_READ;
822 file_flags = O_RDONLY;
823 }
824 else if (mode == PerfMemory::PERF_MODE_RW) {
825 #ifdef LATER
826 mmap_prot = PROT_READ | PROT_WRITE;
827 file_flags = O_RDWR;
828 #else
829 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
830 "Unsupported access mode");
831 #endif
832 }
833 else {
834 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
835 "Illegal access mode");
836 }
837
838 if (user == NULL || strlen(user) == 0) {
839 luser = get_user_name(vmid, CHECK);
840 }
841 else {
842 luser = user;
843 }
844
845 if (luser == NULL) {
846 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
847 "Could not map vmid to user Name");
848 }
849
850 char* dirname = get_user_tmp_dir(luser);
851
852 // since we don't follow symbolic links when creating the backing
853 // store file, we don't follow them when attaching either.
854 //
855 if (!is_directory_secure(dirname)) {
856 FREE_C_HEAP_ARRAY(char, dirname);
857 if (luser != user) {
858 FREE_C_HEAP_ARRAY(char, luser);
859 }
860 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
861 "Process not found");
862 }
863
864 char* filename = get_sharedmem_filename(dirname, vmid);
865
866 // copy heap memory to resource memory. the open_sharedmem_file
867 // method below need to use the filename, but could throw an
868 // exception. using a resource array prevents the leak that
869 // would otherwise occur.
870 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
871 strcpy(rfilename, filename);
872
873 // free the c heap resources that are no longer needed
874 if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
875 FREE_C_HEAP_ARRAY(char, dirname);
876 FREE_C_HEAP_ARRAY(char, filename);
877
878 // open the shared memory file for the give vmid
879 fd = open_sharedmem_file(rfilename, file_flags, CHECK);
880 assert(fd != OS_ERR, "unexpected value");
881
882 if (*sizep == 0) {
883 size = sharedmem_filesize(fd, CHECK);
884 assert(size != 0, "unexpected size");
885 } else {
886 size = *sizep;
887 }
888
889 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
890
891 // attempt to close the file - restart if it gets interrupted,
892 // but ignore other failures
893 RESTARTABLE(::close(fd), result);
894 assert(result != OS_ERR, "could not close file");
895
896 if (mapAddress == MAP_FAILED) {
897 if (PrintMiscellaneous && Verbose) {
898 warning("mmap failed: %s\n", strerror(errno));
899 }
900 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
901 "Could not map PerfMemory");
902 }
903
904 *addr = mapAddress;
905 *sizep = size;
906
907 if (PerfTraceMemOps) {
908 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
909 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
910 }
911 }
912
913
914
915
916 // create the PerfData memory region
917 //
918 // This method creates the memory region used to store performance
919 // data for the JVM. The memory may be created in standard or
920 // shared memory.
921 //
922 void PerfMemory::create_memory_region(size_t size) {
923
924 if (PerfDisableSharedMem) {
925 // do not share the memory for the performance data.
926 _start = create_standard_memory(size);
927 }
928 else {
929 _start = create_shared_memory(size);
930 if (_start == NULL) {
931
932 // creation of the shared memory region failed, attempt
933 // to create a contiguous, non-shared memory region instead.
934 //
935 if (PrintMiscellaneous && Verbose) {
936 warning("Reverting to non-shared PerfMemory region.\n");
937 }
938 PerfDisableSharedMem = true;
939 _start = create_standard_memory(size);
940 }
941 }
942
943 if (_start != NULL) _capacity = size;
944
945 }
946
947 // delete the PerfData memory region
948 //
949 // This method deletes the memory region used to store performance
950 // data for the JVM. The memory region indicated by the <address, size>
951 // tuple will be inaccessible after a call to this method.
952 //
953 void PerfMemory::delete_memory_region() {
954
955 assert((start() != NULL && capacity() > 0), "verify proper state");
956
957 // If user specifies PerfDataSaveFile, it will save the performance data
958 // to the specified file name no matter whether PerfDataSaveToFile is specified
959 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
960 // -XX:+PerfDataSaveToFile.
961 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
962 save_memory_to_file(start(), capacity());
963 }
964
965 if (PerfDisableSharedMem) {
966 delete_standard_memory(start(), capacity());
967 }
968 else {
969 delete_shared_memory(start(), capacity());
970 }
971 }
972
973 // attach to the PerfData memory region for another JVM
974 //
975 // This method returns an <address, size> tuple that points to
976 // a memory buffer that is kept reasonably synchronized with
977 // the PerfData memory region for the indicated JVM. This
978 // buffer may be kept in synchronization via shared memory
979 // or some other mechanism that keeps the buffer updated.
980 //
981 // If the JVM chooses not to support the attachability feature,
982 // this method should throw an UnsupportedOperation exception.
983 //
984 // This implementation utilizes named shared memory to map
985 // the indicated process's PerfData memory region into this JVMs
986 // address space.
987 //
988 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
989
990 if (vmid == 0 || vmid == os::current_process_id()) {
991 *addrp = start();
992 *sizep = capacity();
993 return;
994 }
995
996 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
997 }
998
999 // detach from the PerfData memory region of another JVM
1000 //
1001 // This method detaches the PerfData memory region of another
1002 // JVM, specified as an <address, size> tuple of a buffer
1003 // in this process's address space. This method may perform
1004 // arbitrary actions to accomplish the detachment. The memory
1005 // region specified by <address, size> will be inaccessible after
1006 // a call to this method.
1007 //
1008 // If the JVM chooses not to support the attachability feature,
1009 // this method should throw an UnsupportedOperation exception.
1010 //
1011 // This implementation utilizes named shared memory to detach
1012 // the indicated process's PerfData memory region from this
1013 // process's address space.
1014 //
1015 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1016
1017 assert(addr != 0, "address sanity check");
1018 assert(bytes > 0, "capacity sanity check");
1019
1020 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1021 // prevent accidental detachment of this process's PerfMemory region
1022 return;
1023 }
1024
1025 unmap_shared(addr, bytes);
1026 }