perfMemory_linux.cpp revision 7421:55e38e5032af
1169689Skan/* 2169689Skan * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3169689Skan * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4169689Skan * 5169689Skan * This code is free software; you can redistribute it and/or modify it 6169689Skan * under the terms of the GNU General Public License version 2 only, as 7169689Skan * published by the Free Software Foundation. 8169689Skan * 9169689Skan * This code is distributed in the hope that it will be useful, but WITHOUT 10169689Skan * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11169689Skan * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12169689Skan * version 2 for more details (a copy is included in the LICENSE file that 13169689Skan * accompanied this code). 14169689Skan * 15169689Skan * You should have received a copy of the GNU General Public License version 16169689Skan * 2 along with this work; if not, write to the Free Software Foundation, 17169689Skan * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18169689Skan * 19169689Skan * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20169689Skan * or visit www.oracle.com if you need additional information or have any 21169689Skan * questions. 22169689Skan * 23169689Skan */ 24169689Skan 25169689Skan#include "precompiled.hpp" 26169689Skan#include "classfile/vmSymbols.hpp" 27169689Skan#include "memory/allocation.inline.hpp" 28169689Skan#include "memory/resourceArea.hpp" 29169689Skan#include "oops/oop.inline.hpp" 30169689Skan#include "os_linux.inline.hpp" 31169689Skan#include "runtime/handles.inline.hpp" 32169689Skan#include "runtime/perfMemory.hpp" 33169689Skan#include "services/memTracker.hpp" 34169689Skan#include "utilities/exceptions.hpp" 35169689Skan 36169689Skan// put OS-includes here 37169689Skan# include <sys/types.h> 38169689Skan# include <sys/mman.h> 39169689Skan# include <errno.h> 40169689Skan# include <stdio.h> 41169689Skan# include <unistd.h> 42169689Skan# include <sys/stat.h> 43169689Skan# include <signal.h> 44169689Skan# include <pwd.h> 45169689Skan 46169689Skanstatic char* backing_store_file_name = NULL; // name of the backing store 47169689Skan // file, if successfully created. 48169689Skan 49169689Skan// Standard Memory Implementation Details 50169689Skan 51169689Skan// create the PerfData memory region in standard memory. 52169689Skan// 53169689Skanstatic char* create_standard_memory(size_t size) { 54169689Skan 55169689Skan // allocate an aligned chuck of memory 56169689Skan char* mapAddress = os::reserve_memory(size); 57169689Skan 58169689Skan if (mapAddress == NULL) { 59169689Skan return NULL; 60169689Skan } 61169689Skan 62169689Skan // commit memory 63169689Skan if (!os::commit_memory(mapAddress, size, !ExecMem)) { 64169689Skan if (PrintMiscellaneous && Verbose) { 65169689Skan warning("Could not commit PerfData memory\n"); 66169689Skan } 67169689Skan os::release_memory(mapAddress, size); 68169689Skan return NULL; 69169689Skan } 70169689Skan 71169689Skan return mapAddress; 72169689Skan} 73169689Skan 74169689Skan// delete the PerfData memory region 75169689Skan// 76169689Skanstatic void delete_standard_memory(char* addr, size_t size) { 77169689Skan 78169689Skan // there are no persistent external resources to cleanup for standard 79169689Skan // memory. since DestroyJavaVM does not support unloading of the JVM, 80169689Skan // cleanup of the memory resource is not performed. The memory will be 81169689Skan // reclaimed by the OS upon termination of the process. 82169689Skan // 83169689Skan return; 84169689Skan} 85169689Skan 86169689Skan// save the specified memory region to the given file 87169689Skan// 88169689Skan// Note: this function might be called from signal handler (by os::abort()), 89169689Skan// don't allocate heap memory. 90169689Skan// 91169689Skanstatic void save_memory_to_file(char* addr, size_t size) { 92169689Skan 93169689Skan const char* destfile = PerfMemory::get_perfdata_file_path(); 94169689Skan assert(destfile[0] != '\0', "invalid PerfData file path"); 95169689Skan 96169689Skan int result; 97169689Skan 98169689Skan RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 99169689Skan result);; 100169689Skan if (result == OS_ERR) { 101169689Skan if (PrintMiscellaneous && Verbose) { 102169689Skan warning("Could not create Perfdata save file: %s: %s\n", 103169689Skan destfile, strerror(errno)); 104169689Skan } 105169689Skan } else { 106169689Skan int fd = result; 107169689Skan 108169689Skan for (size_t remaining = size; remaining > 0;) { 109169689Skan 110169689Skan RESTARTABLE(::write(fd, addr, remaining), result); 111169689Skan if (result == OS_ERR) { 112169689Skan if (PrintMiscellaneous && Verbose) { 113169689Skan warning("Could not write Perfdata save file: %s: %s\n", 114169689Skan destfile, strerror(errno)); 115169689Skan } 116169689Skan break; 117169689Skan } 118169689Skan 119169689Skan remaining -= (size_t)result; 120169689Skan addr += result; 121169689Skan } 122169689Skan 123169689Skan result = ::close(fd); 124169689Skan if (PrintMiscellaneous && Verbose) { 125169689Skan if (result == OS_ERR) { 126169689Skan warning("Could not close %s: %s\n", destfile, strerror(errno)); 127169689Skan } 128169689Skan } 129169689Skan } 130169689Skan FREE_C_HEAP_ARRAY(char, destfile, mtInternal); 131169689Skan} 132169689Skan 133169689Skan 134169689Skan// Shared Memory Implementation Details 135169689Skan 136169689Skan// Note: the solaris and linux shared memory implementation uses the mmap 137169689Skan// interface with a backing store file to implement named shared memory. 138169689Skan// Using the file system as the name space for shared memory allows a 139169689Skan// common name space to be supported across a variety of platforms. It 140169689Skan// also provides a name space that Java applications can deal with through 141169689Skan// simple file apis. 142169689Skan// 143169689Skan// The solaris and linux implementations store the backing store file in 144169689Skan// a user specific temporary directory located in the /tmp file system, 145169689Skan// which is always a local file system and is sometimes a RAM based file 146169689Skan// system. 147169689Skan 148169689Skan// return the user specific temporary directory name. 149169689Skan// 150169689Skan// the caller is expected to free the allocated memory. 151169689Skan// 152169689Skanstatic char* get_user_tmp_dir(const char* user) { 153169689Skan 154169689Skan const char* tmpdir = os::get_temp_directory(); 155169689Skan const char* perfdir = PERFDATA_NAME; 156169689Skan size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 157169689Skan char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 158169689Skan 159169689Skan // construct the path name to user specific tmp directory 160169689Skan snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 161169689Skan 162169689Skan return dirname; 163169689Skan} 164169689Skan 165169689Skan// convert the given file name into a process id. if the file 166169689Skan// does not meet the file naming constraints, return 0. 167169689Skan// 168169689Skanstatic pid_t filename_to_pid(const char* filename) { 169169689Skan 170169689Skan // a filename that doesn't begin with a digit is not a 171169689Skan // candidate for conversion. 172169689Skan // 173169689Skan if (!isdigit(*filename)) { 174169689Skan return 0; 175169689Skan } 176169689Skan 177169689Skan // check if file name can be converted to an integer without 178169689Skan // any leftover characters. 179169689Skan // 180169689Skan char* remainder = NULL; 181169689Skan errno = 0; 182169689Skan pid_t pid = (pid_t)strtol(filename, &remainder, 10); 183169689Skan 184169689Skan if (errno != 0) { 185169689Skan return 0; 186169689Skan } 187169689Skan 188169689Skan // check for left over characters. If any, then the filename is 189169689Skan // not a candidate for conversion. 190169689Skan // 191169689Skan if (remainder != NULL && *remainder != '\0') { 192169689Skan return 0; 193169689Skan } 194169689Skan 195169689Skan // successful conversion, return the pid 196169689Skan return pid; 197169689Skan} 198169689Skan 199169689Skan 200169689Skan// check if the given path is considered a secure directory for 201169689Skan// the backing store files. Returns true if the directory exists 202169689Skan// and is considered a secure location. Returns false if the path 203169689Skan// is a symbolic link or if an error occurred. 204169689Skan// 205169689Skanstatic bool is_directory_secure(const char* path) { 206169689Skan struct stat statbuf; 207169689Skan int result = 0; 208169689Skan 209169689Skan RESTARTABLE(::lstat(path, &statbuf), result); 210169689Skan if (result == OS_ERR) { 211169689Skan return false; 212169689Skan } 213169689Skan 214169689Skan // the path exists, now check it's mode 215169689Skan if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) { 216169689Skan // the path represents a link or some non-directory file type, 217169689Skan // which is not what we expected. declare it insecure. 218169689Skan // 219169689Skan return false; 220169689Skan } 221169689Skan else { 222169689Skan // we have an existing directory, check if the permissions are safe. 223169689Skan // 224169689Skan if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) { 225169689Skan // the directory is open for writing and could be subjected 226169689Skan // to a symlnk attack. declare it insecure. 227169689Skan // 228169689Skan return false; 229169689Skan } 230169689Skan } 231169689Skan return true; 232169689Skan} 233169689Skan 234169689Skan 235169689Skan// return the user name for the given user id 236169689Skan// 237169689Skan// the caller is expected to free the allocated memory. 238169689Skan// 239169689Skanstatic char* get_user_name(uid_t uid) { 240169689Skan 241169689Skan struct passwd pwent; 242169689Skan 243169689Skan // determine the max pwbuf size from sysconf, and hardcode 244169689Skan // a default if this not available through sysconf. 245169689Skan // 246169689Skan long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 247169689Skan if (bufsize == -1) 248169689Skan bufsize = 1024; 249169689Skan 250169689Skan char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 251169689Skan 252169689Skan // POSIX interface to getpwuid_r is used on LINUX 253169689Skan struct passwd* p; 254169689Skan int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 255169689Skan 256169689Skan if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 257169689Skan if (PrintMiscellaneous && Verbose) { 258169689Skan if (result != 0) { 259169689Skan warning("Could not retrieve passwd entry: %s\n", 260169689Skan strerror(result)); 261169689Skan } 262169689Skan else if (p == NULL) { 263169689Skan // this check is added to protect against an observed problem 264169689Skan // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0, 265169689Skan // indicating success, but has p == NULL. This was observed when 266169689Skan // inserting a file descriptor exhaustion fault prior to the call 267169689Skan // getpwuid_r() call. In this case, error is set to the appropriate 268169689Skan // error condition, but this is undocumented behavior. This check 269169689Skan // is safe under any condition, but the use of errno in the output 270169689Skan // message may result in an erroneous message. 271169689Skan // Bug Id 89052 was opened with RedHat. 272169689Skan // 273169689Skan warning("Could not retrieve passwd entry: %s\n", 274169689Skan strerror(errno)); 275169689Skan } 276169689Skan else { 277169689Skan warning("Could not determine user name: %s\n", 278169689Skan p->pw_name == NULL ? "pw_name = NULL" : 279169689Skan "pw_name zero length"); 280169689Skan } 281169689Skan } 282169689Skan FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); 283169689Skan return NULL; 284169689Skan } 285169689Skan 286169689Skan char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 287169689Skan strcpy(user_name, p->pw_name); 288169689Skan 289169689Skan FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); 290169689Skan return user_name; 291169689Skan} 292169689Skan 293169689Skan// return the name of the user that owns the process identified by vmid. 294169689Skan// 295169689Skan// This method uses a slow directory search algorithm to find the backing 296169689Skan// store file for the specified vmid and returns the user name, as determined 297169689Skan// by the user name suffix of the hsperfdata_<username> directory name. 298169689Skan// 299169689Skan// the caller is expected to free the allocated memory. 300169689Skan// 301169689Skanstatic char* get_user_name_slow(int vmid, TRAPS) { 302169689Skan 303169689Skan // short circuit the directory search if the process doesn't even exist. 304169689Skan if (kill(vmid, 0) == OS_ERR) { 305169689Skan if (errno == ESRCH) { 306169689Skan THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 307169689Skan "Process not found"); 308169689Skan } 309169689Skan else /* EPERM */ { 310169689Skan THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 311169689Skan } 312169689Skan } 313169689Skan 314169689Skan // directory search 315169689Skan char* oldest_user = NULL; 316169689Skan time_t oldest_ctime = 0; 317169689Skan 318169689Skan const char* tmpdirname = os::get_temp_directory(); 319169689Skan 320169689Skan DIR* tmpdirp = os::opendir(tmpdirname); 321169689Skan 322169689Skan if (tmpdirp == NULL) { 323169689Skan return NULL; 324169689Skan } 325169689Skan 326169689Skan // for each entry in the directory that matches the pattern hsperfdata_*, 327169689Skan // open the directory and check if the file for the given vmid exists. 328169689Skan // The file with the expected name and the latest creation date is used 329169689Skan // to determine the user name for the process id. 330169689Skan // 331169689Skan struct dirent* dentry; 332169689Skan char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); 333169689Skan errno = 0; 334169689Skan while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 335169689Skan 336169689Skan // check if the directory entry is a hsperfdata file 337169689Skan if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 338169689Skan continue; 339169689Skan } 340169689Skan 341169689Skan char* usrdir_name = NEW_C_HEAP_ARRAY(char, 342169689Skan strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 343169689Skan strcpy(usrdir_name, tmpdirname); 344169689Skan strcat(usrdir_name, "/"); 345169689Skan strcat(usrdir_name, dentry->d_name); 346169689Skan 347169689Skan DIR* subdirp = os::opendir(usrdir_name); 348169689Skan 349169689Skan if (subdirp == NULL) { 350169689Skan FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 351169689Skan continue; 352169689Skan } 353169689Skan 354169689Skan // Since we don't create the backing store files in directories 355169689Skan // pointed to by symbolic links, we also don't follow them when 356169689Skan // looking for the files. We check for a symbolic link after the 357169689Skan // call to opendir in order to eliminate a small window where the 358169689Skan // symlink can be exploited. 359169689Skan // 360169689Skan if (!is_directory_secure(usrdir_name)) { 361169689Skan FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 362169689Skan os::closedir(subdirp); 363169689Skan continue; 364169689Skan } 365169689Skan 366169689Skan struct dirent* udentry; 367169689Skan char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); 368169689Skan errno = 0; 369169689Skan while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 370169689Skan 371169689Skan if (filename_to_pid(udentry->d_name) == vmid) { 372169689Skan struct stat statbuf; 373169689Skan int result; 374169689Skan 375169689Skan char* filename = NEW_C_HEAP_ARRAY(char, 376169689Skan strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 377169689Skan 378169689Skan strcpy(filename, usrdir_name); 379169689Skan strcat(filename, "/"); 380169689Skan strcat(filename, udentry->d_name); 381169689Skan 382169689Skan // don't follow symbolic links for the file 383169689Skan RESTARTABLE(::lstat(filename, &statbuf), result); 384169689Skan if (result == OS_ERR) { 385169689Skan FREE_C_HEAP_ARRAY(char, filename, mtInternal); 386169689Skan continue; 387169689Skan } 388169689Skan 389169689Skan // skip over files that are not regular files. 390169689Skan if (!S_ISREG(statbuf.st_mode)) { 391169689Skan FREE_C_HEAP_ARRAY(char, filename, mtInternal); 392169689Skan continue; 393169689Skan } 394169689Skan 395169689Skan // compare and save filename with latest creation time 396169689Skan if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 397169689Skan 398169689Skan if (statbuf.st_ctime > oldest_ctime) { 399169689Skan char* user = strchr(dentry->d_name, '_') + 1; 400169689Skan 401169689Skan if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user, mtInternal); 402169689Skan oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 403169689Skan 404169689Skan strcpy(oldest_user, user); 405169689Skan oldest_ctime = statbuf.st_ctime; 406169689Skan } 407169689Skan } 408169689Skan 409169689Skan FREE_C_HEAP_ARRAY(char, filename, mtInternal); 410169689Skan } 411169689Skan } 412169689Skan os::closedir(subdirp); 413169689Skan FREE_C_HEAP_ARRAY(char, udbuf, mtInternal); 414169689Skan FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 415169689Skan } 416169689Skan os::closedir(tmpdirp); 417169689Skan FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal); 418169689Skan 419169689Skan return(oldest_user); 420169689Skan} 421169689Skan 422169689Skan// return the name of the user that owns the JVM indicated by the given vmid. 423169689Skan// 424169689Skanstatic char* get_user_name(int vmid, TRAPS) { 425169689Skan return get_user_name_slow(vmid, THREAD); 426169689Skan} 427169689Skan 428169689Skan// return the file name of the backing store file for the named 429169689Skan// shared memory region for the given user name and vmid. 430169689Skan// 431169689Skan// the caller is expected to free the allocated memory. 432169689Skan// 433169689Skanstatic char* get_sharedmem_filename(const char* dirname, int vmid) { 434169689Skan 435169689Skan // add 2 for the file separator and a null terminator. 436169689Skan size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 437169689Skan 438169689Skan char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 439169689Skan snprintf(name, nbytes, "%s/%d", dirname, vmid); 440169689Skan 441169689Skan return name; 442169689Skan} 443169689Skan 444169689Skan 445169689Skan// remove file 446169689Skan// 447169689Skan// this method removes the file specified by the given path 448169689Skan// 449169689Skanstatic void remove_file(const char* path) { 450169689Skan 451169689Skan int result; 452169689Skan 453169689Skan // if the file is a directory, the following unlink will fail. since 454169689Skan // we don't expect to find directories in the user temp directory, we 455169689Skan // won't try to handle this situation. even if accidentially or 456169689Skan // maliciously planted, the directory's presence won't hurt anything. 457169689Skan // 458169689Skan RESTARTABLE(::unlink(path), result); 459169689Skan if (PrintMiscellaneous && Verbose && result == OS_ERR) { 460169689Skan if (errno != ENOENT) { 461169689Skan warning("Could not unlink shared memory backing" 462169689Skan " store file %s : %s\n", path, strerror(errno)); 463169689Skan } 464169689Skan } 465169689Skan} 466169689Skan 467169689Skan 468169689Skan// remove file 469169689Skan// 470169689Skan// this method removes the file with the given file name in the 471169689Skan// named directory. 472169689Skan// 473169689Skanstatic void remove_file(const char* dirname, const char* filename) { 474169689Skan 475169689Skan size_t nbytes = strlen(dirname) + strlen(filename) + 2; 476169689Skan char* path = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 477169689Skan 478169689Skan strcpy(path, dirname); 479169689Skan strcat(path, "/"); 480169689Skan strcat(path, filename); 481169689Skan 482169689Skan remove_file(path); 483169689Skan 484169689Skan FREE_C_HEAP_ARRAY(char, path, mtInternal); 485169689Skan} 486169689Skan 487169689Skan 488169689Skan// cleanup stale shared memory resources 489169689Skan// 490169689Skan// This method attempts to remove all stale shared memory files in 491169689Skan// the named user temporary directory. It scans the named directory 492169689Skan// for files matching the pattern ^$[0-9]*$. For each file found, the 493169689Skan// process id is extracted from the file name and a test is run to 494169689Skan// determine if the process is alive. If the process is not alive, 495169689Skan// any stale file resources are removed. 496169689Skan// 497169689Skanstatic void cleanup_sharedmem_resources(const char* dirname) { 498169689Skan 499169689Skan // open the user temp directory 500169689Skan DIR* dirp = os::opendir(dirname); 501169689Skan 502169689Skan if (dirp == NULL) { 503169689Skan // directory doesn't exist, so there is nothing to cleanup 504169689Skan return; 505169689Skan } 506169689Skan 507169689Skan if (!is_directory_secure(dirname)) { 508169689Skan // the directory is not a secure directory 509169689Skan return; 510169689Skan } 511169689Skan 512169689Skan // for each entry in the directory that matches the expected file 513169689Skan // name pattern, determine if the file resources are stale and if 514169689Skan // so, remove the file resources. Note, instrumented HotSpot processes 515169689Skan // for this user may start and/or terminate during this search and 516169689Skan // remove or create new files in this directory. The behavior of this 517169689Skan // loop under these conditions is dependent upon the implementation of 518169689Skan // opendir/readdir. 519169689Skan // 520169689Skan struct dirent* entry; 521169689Skan char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); 522169689Skan errno = 0; 523169689Skan while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 524169689Skan 525169689Skan pid_t pid = filename_to_pid(entry->d_name); 526169689Skan 527169689Skan if (pid == 0) { 528169689Skan 529169689Skan if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 530169689Skan 531169689Skan // attempt to remove all unexpected files, except "." and ".." 532169689Skan remove_file(dirname, entry->d_name); 533169689Skan } 534169689Skan 535169689Skan errno = 0; 536169689Skan continue; 537169689Skan } 538169689Skan 539169689Skan // we now have a file name that converts to a valid integer 540169689Skan // that could represent a process id . if this process id 541169689Skan // matches the current process id or the process is not running, 542169689Skan // then remove the stale file resources. 543169689Skan // 544169689Skan // process liveness is detected by sending signal number 0 to 545169689Skan // the process id (see kill(2)). if kill determines that the 546169689Skan // process does not exist, then the file resources are removed. 547169689Skan // if kill determines that that we don't have permission to 548169689Skan // signal the process, then the file resources are assumed to 549169689Skan // be stale and are removed because the resources for such a 550169689Skan // process should be in a different user specific directory. 551169689Skan // 552169689Skan if ((pid == os::current_process_id()) || 553169689Skan (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 554169689Skan 555169689Skan remove_file(dirname, entry->d_name); 556169689Skan } 557169689Skan errno = 0; 558169689Skan } 559169689Skan os::closedir(dirp); 560169689Skan FREE_C_HEAP_ARRAY(char, dbuf, mtInternal); 561169689Skan} 562169689Skan 563169689Skan// make the user specific temporary directory. Returns true if 564169689Skan// the directory exists and is secure upon return. Returns false 565169689Skan// if the directory exists but is either a symlink, is otherwise 566169689Skan// insecure, or if an error occurred. 567169689Skan// 568169689Skanstatic bool make_user_tmp_dir(const char* dirname) { 569169689Skan 570169689Skan // create the directory with 0755 permissions. note that the directory 571169689Skan // will be owned by euid::egid, which may not be the same as uid::gid. 572169689Skan // 573 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 574 if (errno == EEXIST) { 575 // The directory already exists and was probably created by another 576 // JVM instance. However, this could also be the result of a 577 // deliberate symlink. Verify that the existing directory is safe. 578 // 579 if (!is_directory_secure(dirname)) { 580 // directory is not secure 581 if (PrintMiscellaneous && Verbose) { 582 warning("%s directory is insecure\n", dirname); 583 } 584 return false; 585 } 586 } 587 else { 588 // we encountered some other failure while attempting 589 // to create the directory 590 // 591 if (PrintMiscellaneous && Verbose) { 592 warning("could not create directory %s: %s\n", 593 dirname, strerror(errno)); 594 } 595 return false; 596 } 597 } 598 return true; 599} 600 601// create the shared memory file resources 602// 603// This method creates the shared memory file with the given size 604// This method also creates the user specific temporary directory, if 605// it does not yet exist. 606// 607static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 608 609 // make the user temporary directory 610 if (!make_user_tmp_dir(dirname)) { 611 // could not make/find the directory or the found directory 612 // was not secure 613 return -1; 614 } 615 616 int result; 617 618 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result); 619 if (result == OS_ERR) { 620 if (PrintMiscellaneous && Verbose) { 621 warning("could not create file %s: %s\n", filename, strerror(errno)); 622 } 623 return -1; 624 } 625 626 // save the file descriptor 627 int fd = result; 628 629 // set the file size 630 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 631 if (result == OS_ERR) { 632 if (PrintMiscellaneous && Verbose) { 633 warning("could not set shared memory file size: %s\n", strerror(errno)); 634 } 635 ::close(fd); 636 return -1; 637 } 638 639 // Verify that we have enough disk space for this file. 640 // We'll get random SIGBUS crashes on memory accesses if 641 // we don't. 642 643 for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) { 644 int zero_int = 0; 645 result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos)); 646 if (result == -1 ) break; 647 RESTARTABLE(::write(fd, &zero_int, 1), result); 648 if (result != 1) { 649 if (errno == ENOSPC) { 650 warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename); 651 } 652 break; 653 } 654 } 655 656 if (result != -1) { 657 return fd; 658 } else { 659 ::close(fd); 660 return -1; 661 } 662} 663 664// open the shared memory file for the given user and vmid. returns 665// the file descriptor for the open file or -1 if the file could not 666// be opened. 667// 668static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 669 670 // open the file 671 int result; 672 RESTARTABLE(::open(filename, oflags), result); 673 if (result == OS_ERR) { 674 if (errno == ENOENT) { 675 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 676 "Process not found", OS_ERR); 677 } 678 else if (errno == EACCES) { 679 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 680 "Permission denied", OS_ERR); 681 } 682 else { 683 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR); 684 } 685 } 686 687 return result; 688} 689 690// create a named shared memory region. returns the address of the 691// memory region on success or NULL on failure. A return value of 692// NULL will ultimately disable the shared memory feature. 693// 694// On Solaris and Linux, the name space for shared memory objects 695// is the file system name space. 696// 697// A monitoring application attaching to a JVM does not need to know 698// the file system name of the shared memory object. However, it may 699// be convenient for applications to discover the existence of newly 700// created and terminating JVMs by watching the file system name space 701// for files being created or removed. 702// 703static char* mmap_create_shared(size_t size) { 704 705 int result; 706 int fd; 707 char* mapAddress; 708 709 int vmid = os::current_process_id(); 710 711 char* user_name = get_user_name(geteuid()); 712 713 if (user_name == NULL) 714 return NULL; 715 716 char* dirname = get_user_tmp_dir(user_name); 717 char* filename = get_sharedmem_filename(dirname, vmid); 718 719 // cleanup any stale shared memory files 720 cleanup_sharedmem_resources(dirname); 721 722 assert(((size > 0) && (size % os::vm_page_size() == 0)), 723 "unexpected PerfMemory region size"); 724 725 fd = create_sharedmem_resources(dirname, filename, size); 726 727 FREE_C_HEAP_ARRAY(char, user_name, mtInternal); 728 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 729 730 if (fd == -1) { 731 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 732 return NULL; 733 } 734 735 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 736 737 result = ::close(fd); 738 assert(result != OS_ERR, "could not close file"); 739 740 if (mapAddress == MAP_FAILED) { 741 if (PrintMiscellaneous && Verbose) { 742 warning("mmap failed - %s\n", strerror(errno)); 743 } 744 remove_file(filename); 745 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 746 return NULL; 747 } 748 749 // save the file name for use in delete_shared_memory() 750 backing_store_file_name = filename; 751 752 // clear the shared memory region 753 (void)::memset((void*) mapAddress, 0, size); 754 755 // it does not go through os api, the operation has to record from here 756 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); 757 758 return mapAddress; 759} 760 761// release a named shared memory region 762// 763static void unmap_shared(char* addr, size_t bytes) { 764 os::release_memory(addr, bytes); 765} 766 767// create the PerfData memory region in shared memory. 768// 769static char* create_shared_memory(size_t size) { 770 771 // create the shared memory region. 772 return mmap_create_shared(size); 773} 774 775// delete the shared PerfData memory region 776// 777static void delete_shared_memory(char* addr, size_t size) { 778 779 // cleanup the persistent shared memory resources. since DestroyJavaVM does 780 // not support unloading of the JVM, unmapping of the memory resource is 781 // not performed. The memory will be reclaimed by the OS upon termination of 782 // the process. The backing store file is deleted from the file system. 783 784 assert(!PerfDisableSharedMem, "shouldn't be here"); 785 786 if (backing_store_file_name != NULL) { 787 remove_file(backing_store_file_name); 788 // Don't.. Free heap memory could deadlock os::abort() if it is called 789 // from signal handler. OS will reclaim the heap memory. 790 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 791 backing_store_file_name = NULL; 792 } 793} 794 795// return the size of the file for the given file descriptor 796// or 0 if it is not a valid size for a shared memory file 797// 798static size_t sharedmem_filesize(int fd, TRAPS) { 799 800 struct stat statbuf; 801 int result; 802 803 RESTARTABLE(::fstat(fd, &statbuf), result); 804 if (result == OS_ERR) { 805 if (PrintMiscellaneous && Verbose) { 806 warning("fstat failed: %s\n", strerror(errno)); 807 } 808 THROW_MSG_0(vmSymbols::java_io_IOException(), 809 "Could not determine PerfMemory size"); 810 } 811 812 if ((statbuf.st_size == 0) || 813 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 814 THROW_MSG_0(vmSymbols::java_lang_Exception(), 815 "Invalid PerfMemory size"); 816 } 817 818 return (size_t)statbuf.st_size; 819} 820 821// attach to a named shared memory region. 822// 823static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 824 825 char* mapAddress; 826 int result; 827 int fd; 828 size_t size = 0; 829 const char* luser = NULL; 830 831 int mmap_prot; 832 int file_flags; 833 834 ResourceMark rm; 835 836 // map the high level access mode to the appropriate permission 837 // constructs for the file and the shared memory mapping. 838 if (mode == PerfMemory::PERF_MODE_RO) { 839 mmap_prot = PROT_READ; 840 file_flags = O_RDONLY; 841 } 842 else if (mode == PerfMemory::PERF_MODE_RW) { 843#ifdef LATER 844 mmap_prot = PROT_READ | PROT_WRITE; 845 file_flags = O_RDWR; 846#else 847 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 848 "Unsupported access mode"); 849#endif 850 } 851 else { 852 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 853 "Illegal access mode"); 854 } 855 856 if (user == NULL || strlen(user) == 0) { 857 luser = get_user_name(vmid, CHECK); 858 } 859 else { 860 luser = user; 861 } 862 863 if (luser == NULL) { 864 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 865 "Could not map vmid to user Name"); 866 } 867 868 char* dirname = get_user_tmp_dir(luser); 869 870 // since we don't follow symbolic links when creating the backing 871 // store file, we don't follow them when attaching either. 872 // 873 if (!is_directory_secure(dirname)) { 874 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 875 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 876 "Process not found"); 877 } 878 879 char* filename = get_sharedmem_filename(dirname, vmid); 880 881 // copy heap memory to resource memory. the open_sharedmem_file 882 // method below need to use the filename, but could throw an 883 // exception. using a resource array prevents the leak that 884 // would otherwise occur. 885 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 886 strcpy(rfilename, filename); 887 888 // free the c heap resources that are no longer needed 889 if (luser != user) FREE_C_HEAP_ARRAY(char, luser, mtInternal); 890 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 891 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 892 893 // open the shared memory file for the give vmid 894 fd = open_sharedmem_file(rfilename, file_flags, THREAD); 895 896 if (fd == OS_ERR) { 897 return; 898 } 899 900 if (HAS_PENDING_EXCEPTION) { 901 ::close(fd); 902 return; 903 } 904 905 if (*sizep == 0) { 906 size = sharedmem_filesize(fd, CHECK); 907 } else { 908 size = *sizep; 909 } 910 911 assert(size > 0, "unexpected size <= 0"); 912 913 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 914 915 result = ::close(fd); 916 assert(result != OS_ERR, "could not close file"); 917 918 if (mapAddress == MAP_FAILED) { 919 if (PrintMiscellaneous && Verbose) { 920 warning("mmap failed: %s\n", strerror(errno)); 921 } 922 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 923 "Could not map PerfMemory"); 924 } 925 926 // it does not go through os api, the operation has to record from here 927 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); 928 929 *addr = mapAddress; 930 *sizep = size; 931 932 if (PerfTraceMemOps) { 933 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 934 INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress)); 935 } 936} 937 938 939 940 941// create the PerfData memory region 942// 943// This method creates the memory region used to store performance 944// data for the JVM. The memory may be created in standard or 945// shared memory. 946// 947void PerfMemory::create_memory_region(size_t size) { 948 949 if (PerfDisableSharedMem) { 950 // do not share the memory for the performance data. 951 _start = create_standard_memory(size); 952 } 953 else { 954 _start = create_shared_memory(size); 955 if (_start == NULL) { 956 957 // creation of the shared memory region failed, attempt 958 // to create a contiguous, non-shared memory region instead. 959 // 960 if (PrintMiscellaneous && Verbose) { 961 warning("Reverting to non-shared PerfMemory region.\n"); 962 } 963 PerfDisableSharedMem = true; 964 _start = create_standard_memory(size); 965 } 966 } 967 968 if (_start != NULL) _capacity = size; 969 970} 971 972// delete the PerfData memory region 973// 974// This method deletes the memory region used to store performance 975// data for the JVM. The memory region indicated by the <address, size> 976// tuple will be inaccessible after a call to this method. 977// 978void PerfMemory::delete_memory_region() { 979 980 assert((start() != NULL && capacity() > 0), "verify proper state"); 981 982 // If user specifies PerfDataSaveFile, it will save the performance data 983 // to the specified file name no matter whether PerfDataSaveToFile is specified 984 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 985 // -XX:+PerfDataSaveToFile. 986 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 987 save_memory_to_file(start(), capacity()); 988 } 989 990 if (PerfDisableSharedMem) { 991 delete_standard_memory(start(), capacity()); 992 } 993 else { 994 delete_shared_memory(start(), capacity()); 995 } 996} 997 998// attach to the PerfData memory region for another JVM 999// 1000// This method returns an <address, size> tuple that points to 1001// a memory buffer that is kept reasonably synchronized with 1002// the PerfData memory region for the indicated JVM. This 1003// buffer may be kept in synchronization via shared memory 1004// or some other mechanism that keeps the buffer updated. 1005// 1006// If the JVM chooses not to support the attachability feature, 1007// this method should throw an UnsupportedOperation exception. 1008// 1009// This implementation utilizes named shared memory to map 1010// the indicated process's PerfData memory region into this JVMs 1011// address space. 1012// 1013void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1014 1015 if (vmid == 0 || vmid == os::current_process_id()) { 1016 *addrp = start(); 1017 *sizep = capacity(); 1018 return; 1019 } 1020 1021 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1022} 1023 1024// detach from the PerfData memory region of another JVM 1025// 1026// This method detaches the PerfData memory region of another 1027// JVM, specified as an <address, size> tuple of a buffer 1028// in this process's address space. This method may perform 1029// arbitrary actions to accomplish the detachment. The memory 1030// region specified by <address, size> will be inaccessible after 1031// a call to this method. 1032// 1033// If the JVM chooses not to support the attachability feature, 1034// this method should throw an UnsupportedOperation exception. 1035// 1036// This implementation utilizes named shared memory to detach 1037// the indicated process's PerfData memory region from this 1038// process's address space. 1039// 1040void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1041 1042 assert(addr != 0, "address sanity check"); 1043 assert(bytes > 0, "capacity sanity check"); 1044 1045 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1046 // prevent accidental detachment of this process's PerfMemory region 1047 return; 1048 } 1049 1050 unmap_shared(addr, bytes); 1051} 1052