1 /* 2 * Copyright (c) 1999, 2013, 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 // no precompiled headers 26 #include "classfile/classLoader.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "code/icBuffer.hpp" 30 #include "code/vtableStubs.hpp" 31 #include "compiler/compileBroker.hpp" 32 #include "compiler/disassembler.hpp" 33 #include "interpreter/interpreter.hpp" 34 #include "jvm_linux.h" 35 #include "memory/allocation.inline.hpp" 36 #include "memory/filemap.hpp" 37 #include "mutex_linux.inline.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "os_share_linux.hpp" 40 #include "prims/jniFastGetField.hpp" 41 #include "prims/jvm.h" 42 #include "prims/jvm_misc.hpp" 43 #include "runtime/arguments.hpp" 44 #include "runtime/extendedPC.hpp" 45 #include "runtime/globals.hpp" 46 #include "runtime/interfaceSupport.hpp" 47 #include "runtime/init.hpp" 48 #include "runtime/java.hpp" 49 #include "runtime/javaCalls.hpp" 50 #include "runtime/mutexLocker.hpp" 51 #include "runtime/objectMonitor.hpp" 52 #include "runtime/osThread.hpp" 53 #include "runtime/perfMemory.hpp" 54 #include "runtime/sharedRuntime.hpp" 55 #include "runtime/statSampler.hpp" 56 #include "runtime/stubRoutines.hpp" 57 #include "runtime/thread.inline.hpp" 58 #include "runtime/threadCritical.hpp" 59 #include "runtime/timer.hpp" 60 #include "services/attachListener.hpp" 61 #include "services/memTracker.hpp" 62 #include "services/runtimeService.hpp" 63 #include "utilities/decoder.hpp" 64 #include "utilities/defaultStream.hpp" 65 #include "utilities/events.hpp" 66 #include "utilities/elfFile.hpp" 67 #include "utilities/growableArray.hpp" 68 #include "utilities/vmError.hpp" 69 70 // put OS-includes here 71 # include <sys/types.h> 72 # include <sys/mman.h> 73 # include <sys/stat.h> 74 # include <sys/select.h> 75 # include <pthread.h> 76 # include <signal.h> 77 # include <errno.h> 78 # include <dlfcn.h> 79 # include <stdio.h> 80 # include <unistd.h> 81 # include <sys/resource.h> 82 # include <pthread.h> 83 # include <sys/stat.h> 84 # include <sys/time.h> 85 # include <sys/times.h> 86 # include <sys/utsname.h> 87 # include <sys/socket.h> 88 # include <sys/wait.h> 89 # include <pwd.h> 90 # include <poll.h> 91 # include <semaphore.h> 92 # include <fcntl.h> 93 # include <string.h> 94 # include <syscall.h> 95 # include <sys/sysinfo.h> 96 # include <gnu/libc-version.h> 97 # include <sys/ipc.h> 98 # include <sys/shm.h> 99 # include <link.h> 100 # include <stdint.h> 101 # include <inttypes.h> 102 # include <sys/ioctl.h> 103 104 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling 105 // getrusage() is prepared to handle the associated failure. 106 #ifndef RUSAGE_THREAD 107 #define RUSAGE_THREAD (1) /* only the calling thread */ 108 #endif 109 110 #define MAX_PATH (2 * K) 111 112 // for timer info max values which include all bits 113 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 114 115 #define LARGEPAGES_BIT (1 << 6) 116 //////////////////////////////////////////////////////////////////////////////// 117 // global variables 118 julong os::Linux::_physical_memory = 0; 119 120 address os::Linux::_initial_thread_stack_bottom = NULL; 121 uintptr_t os::Linux::_initial_thread_stack_size = 0; 122 123 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 124 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 125 Mutex* os::Linux::_createThread_lock = NULL; 126 pthread_t os::Linux::_main_thread; 127 int os::Linux::_page_size = -1; 128 const int os::Linux::_vm_default_page_size = (8 * K); 129 bool os::Linux::_is_floating_stack = false; 130 bool os::Linux::_is_NPTL = false; 131 bool os::Linux::_supports_fast_thread_cpu_time = false; 132 const char * os::Linux::_glibc_version = NULL; 133 const char * os::Linux::_libpthread_version = NULL; 134 135 static jlong initial_time_count=0; 136 137 static int clock_tics_per_sec = 100; 138 139 // For diagnostics to print a message once. see run_periodic_checks 140 static sigset_t check_signal_done; 141 static bool check_signals = true;; 142 143 static pid_t _initial_pid = 0; 144 145 /* Signal number used to suspend/resume a thread */ 146 147 /* do not use any signal number less than SIGSEGV, see 4355769 */ 148 static int SR_signum = SIGUSR2; 149 sigset_t SR_sigset; 150 151 /* Used to protect dlsym() calls */ 152 static pthread_mutex_t dl_mutex; 153 154 // Declarations 155 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time); 156 157 #ifdef JAVASE_EMBEDDED 158 class MemNotifyThread: public Thread { 159 friend class VMStructs; 160 public: 161 virtual void run(); 162 163 private: 164 static MemNotifyThread* _memnotify_thread; 165 int _fd; 166 167 public: 168 169 // Constructor 170 MemNotifyThread(int fd); 171 172 // Tester 173 bool is_memnotify_thread() const { return true; } 174 175 // Printing 176 char* name() const { return (char*)"Linux MemNotify Thread"; } 177 178 // Returns the single instance of the MemNotifyThread 179 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; } 180 181 // Create and start the single instance of MemNotifyThread 182 static void start(); 183 }; 184 #endif // JAVASE_EMBEDDED 185 186 // utility functions 187 188 static int SR_initialize(); 189 190 julong os::available_memory() { 191 return Linux::available_memory(); 192 } 193 194 julong os::Linux::available_memory() { 195 // values in struct sysinfo are "unsigned long" 196 struct sysinfo si; 197 sysinfo(&si); 198 199 return (julong)si.freeram * si.mem_unit; 200 } 201 202 julong os::physical_memory() { 203 return Linux::physical_memory(); 204 } 205 206 //////////////////////////////////////////////////////////////////////////////// 207 // environment support 208 209 bool os::getenv(const char* name, char* buf, int len) { 210 const char* val = ::getenv(name); 211 if (val != NULL && strlen(val) < (size_t)len) { 212 strcpy(buf, val); 213 return true; 214 } 215 if (len > 0) buf[0] = 0; // return a null string 216 return false; 217 } 218 219 220 // Return true if user is running as root. 221 222 bool os::have_special_privileges() { 223 static bool init = false; 224 static bool privileges = false; 225 if (!init) { 226 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 227 init = true; 228 } 229 return privileges; 230 } 231 232 233 #ifndef SYS_gettid 234 // i386: 224, ia64: 1105, amd64: 186, sparc 143 235 #ifdef __ia64__ 236 #define SYS_gettid 1105 237 #elif __i386__ 238 #define SYS_gettid 224 239 #elif __amd64__ 240 #define SYS_gettid 186 241 #elif __sparc__ 242 #define SYS_gettid 143 243 #else 244 #error define gettid for the arch 245 #endif 246 #endif 247 248 // Cpu architecture string 249 #if defined(ZERO) 250 static char cpu_arch[] = ZERO_LIBARCH; 251 #elif defined(IA64) 252 static char cpu_arch[] = "ia64"; 253 #elif defined(IA32) 254 static char cpu_arch[] = "i386"; 255 #elif defined(AMD64) 256 static char cpu_arch[] = "amd64"; 257 #elif defined(ARM) 258 static char cpu_arch[] = "arm"; 259 #elif defined(PPC) 260 static char cpu_arch[] = "ppc"; 261 #elif defined(SPARC) 262 # ifdef _LP64 263 static char cpu_arch[] = "sparcv9"; 264 # else 265 static char cpu_arch[] = "sparc"; 266 # endif 267 #else 268 #error Add appropriate cpu_arch setting 269 #endif 270 271 272 // pid_t gettid() 273 // 274 // Returns the kernel thread id of the currently running thread. Kernel 275 // thread id is used to access /proc. 276 // 277 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 278 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 279 // 280 pid_t os::Linux::gettid() { 281 int rslt = syscall(SYS_gettid); 282 if (rslt == -1) { 283 // old kernel, no NPTL support 284 return getpid(); 285 } else { 286 return (pid_t)rslt; 287 } 288 } 289 290 // Most versions of linux have a bug where the number of processors are 291 // determined by looking at the /proc file system. In a chroot environment, 292 // the system call returns 1. This causes the VM to act as if it is 293 // a single processor and elide locking (see is_MP() call). 294 static bool unsafe_chroot_detected = false; 295 static const char *unstable_chroot_error = "/proc file system not found.\n" 296 "Java may be unstable running multithreaded in a chroot " 297 "environment on Linux when /proc filesystem is not mounted."; 298 299 void os::Linux::initialize_system_info() { 300 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 301 if (processor_count() == 1) { 302 pid_t pid = os::Linux::gettid(); 303 char fname[32]; 304 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 305 FILE *fp = fopen(fname, "r"); 306 if (fp == NULL) { 307 unsafe_chroot_detected = true; 308 } else { 309 fclose(fp); 310 } 311 } 312 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 313 assert(processor_count() > 0, "linux error"); 314 } 315 316 void os::init_system_properties_values() { 317 // char arch[12]; 318 // sysinfo(SI_ARCHITECTURE, arch, sizeof(arch)); 319 320 // The next steps are taken in the product version: 321 // 322 // Obtain the JAVA_HOME value from the location of libjvm.so. 323 // This library should be located at: 324 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 325 // 326 // If "/jre/lib/" appears at the right place in the path, then we 327 // assume libjvm.so is installed in a JDK and we use this path. 328 // 329 // Otherwise exit with message: "Could not create the Java virtual machine." 330 // 331 // The following extra steps are taken in the debugging version: 332 // 333 // If "/jre/lib/" does NOT appear at the right place in the path 334 // instead of exit check for $JAVA_HOME environment variable. 335 // 336 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 337 // then we append a fake suffix "hotspot/libjvm.so" to this path so 338 // it looks like libjvm.so is installed there 339 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 340 // 341 // Otherwise exit. 342 // 343 // Important note: if the location of libjvm.so changes this 344 // code needs to be changed accordingly. 345 346 // The next few definitions allow the code to be verbatim: 347 #define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n), mtInternal) 348 #define getenv(n) ::getenv(n) 349 350 /* 351 * See ld(1): 352 * The linker uses the following search paths to locate required 353 * shared libraries: 354 * 1: ... 355 * ... 356 * 7: The default directories, normally /lib and /usr/lib. 357 */ 358 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 359 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 360 #else 361 #define DEFAULT_LIBPATH "/lib:/usr/lib" 362 #endif 363 364 #define EXTENSIONS_DIR "/lib/ext" 365 #define ENDORSED_DIR "/lib/endorsed" 366 #define REG_DIR "/usr/java/packages" 367 368 { 369 /* sysclasspath, java_home, dll_dir */ 370 { 371 char *home_path; 372 char *dll_path; 373 char *pslash; 374 char buf[MAXPATHLEN]; 375 os::jvm_path(buf, sizeof(buf)); 376 377 // Found the full path to libjvm.so. 378 // Now cut the path to <java_home>/jre if we can. 379 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */ 380 pslash = strrchr(buf, '/'); 381 if (pslash != NULL) 382 *pslash = '\0'; /* get rid of /{client|server|hotspot} */ 383 dll_path = malloc(strlen(buf) + 1); 384 if (dll_path == NULL) 385 return; 386 strcpy(dll_path, buf); 387 Arguments::set_dll_dir(dll_path); 388 389 if (pslash != NULL) { 390 pslash = strrchr(buf, '/'); 391 if (pslash != NULL) { 392 *pslash = '\0'; /* get rid of /<arch> */ 393 pslash = strrchr(buf, '/'); 394 if (pslash != NULL) 395 *pslash = '\0'; /* get rid of /lib */ 396 } 397 } 398 399 home_path = malloc(strlen(buf) + 1); 400 if (home_path == NULL) 401 return; 402 strcpy(home_path, buf); 403 Arguments::set_java_home(home_path); 404 405 if (!set_boot_path('/', ':')) 406 return; 407 } 408 409 /* 410 * Where to look for native libraries 411 * 412 * Note: Due to a legacy implementation, most of the library path 413 * is set in the launcher. This was to accomodate linking restrictions 414 * on legacy Linux implementations (which are no longer supported). 415 * Eventually, all the library path setting will be done here. 416 * 417 * However, to prevent the proliferation of improperly built native 418 * libraries, the new path component /usr/java/packages is added here. 419 * Eventually, all the library path setting will be done here. 420 */ 421 { 422 char *ld_library_path; 423 424 /* 425 * Construct the invariant part of ld_library_path. Note that the 426 * space for the colon and the trailing null are provided by the 427 * nulls included by the sizeof operator (so actually we allocate 428 * a byte more than necessary). 429 */ 430 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") + 431 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH)); 432 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch); 433 434 /* 435 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It 436 * should always exist (until the legacy problem cited above is 437 * addressed). 438 */ 439 char *v = getenv("LD_LIBRARY_PATH"); 440 if (v != NULL) { 441 char *t = ld_library_path; 442 /* That's +1 for the colon and +1 for the trailing '\0' */ 443 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1); 444 sprintf(ld_library_path, "%s:%s", v, t); 445 } 446 Arguments::set_library_path(ld_library_path); 447 } 448 449 /* 450 * Extensions directories. 451 * 452 * Note that the space for the colon and the trailing null are provided 453 * by the nulls included by the sizeof operator (so actually one byte more 454 * than necessary is allocated). 455 */ 456 { 457 char *buf = malloc(strlen(Arguments::get_java_home()) + 458 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR)); 459 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR, 460 Arguments::get_java_home()); 461 Arguments::set_ext_dirs(buf); 462 } 463 464 /* Endorsed standards default directory. */ 465 { 466 char * buf; 467 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR)); 468 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 469 Arguments::set_endorsed_dirs(buf); 470 } 471 } 472 473 #undef malloc 474 #undef getenv 475 #undef EXTENSIONS_DIR 476 #undef ENDORSED_DIR 477 478 // Done 479 return; 480 } 481 482 //////////////////////////////////////////////////////////////////////////////// 483 // breakpoint support 484 485 void os::breakpoint() { 486 BREAKPOINT; 487 } 488 489 extern "C" void breakpoint() { 490 // use debugger to set breakpoint here 491 } 492 493 //////////////////////////////////////////////////////////////////////////////// 494 // signal support 495 496 debug_only(static bool signal_sets_initialized = false); 497 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 498 499 bool os::Linux::is_sig_ignored(int sig) { 500 struct sigaction oact; 501 sigaction(sig, (struct sigaction*)NULL, &oact); 502 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 503 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 504 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 505 return true; 506 else 507 return false; 508 } 509 510 void os::Linux::signal_sets_init() { 511 // Should also have an assertion stating we are still single-threaded. 512 assert(!signal_sets_initialized, "Already initialized"); 513 // Fill in signals that are necessarily unblocked for all threads in 514 // the VM. Currently, we unblock the following signals: 515 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 516 // by -Xrs (=ReduceSignalUsage)); 517 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 518 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 519 // the dispositions or masks wrt these signals. 520 // Programs embedding the VM that want to use the above signals for their 521 // own purposes must, at this time, use the "-Xrs" option to prevent 522 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 523 // (See bug 4345157, and other related bugs). 524 // In reality, though, unblocking these signals is really a nop, since 525 // these signals are not blocked by default. 526 sigemptyset(&unblocked_sigs); 527 sigemptyset(&allowdebug_blocked_sigs); 528 sigaddset(&unblocked_sigs, SIGILL); 529 sigaddset(&unblocked_sigs, SIGSEGV); 530 sigaddset(&unblocked_sigs, SIGBUS); 531 sigaddset(&unblocked_sigs, SIGFPE); 532 sigaddset(&unblocked_sigs, SR_signum); 533 534 if (!ReduceSignalUsage) { 535 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 536 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 537 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 538 } 539 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 540 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 541 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 542 } 543 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 544 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 545 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 546 } 547 } 548 // Fill in signals that are blocked by all but the VM thread. 549 sigemptyset(&vm_sigs); 550 if (!ReduceSignalUsage) 551 sigaddset(&vm_sigs, BREAK_SIGNAL); 552 debug_only(signal_sets_initialized = true); 553 554 } 555 556 // These are signals that are unblocked while a thread is running Java. 557 // (For some reason, they get blocked by default.) 558 sigset_t* os::Linux::unblocked_signals() { 559 assert(signal_sets_initialized, "Not initialized"); 560 return &unblocked_sigs; 561 } 562 563 // These are the signals that are blocked while a (non-VM) thread is 564 // running Java. Only the VM thread handles these signals. 565 sigset_t* os::Linux::vm_signals() { 566 assert(signal_sets_initialized, "Not initialized"); 567 return &vm_sigs; 568 } 569 570 // These are signals that are blocked during cond_wait to allow debugger in 571 sigset_t* os::Linux::allowdebug_blocked_signals() { 572 assert(signal_sets_initialized, "Not initialized"); 573 return &allowdebug_blocked_sigs; 574 } 575 576 void os::Linux::hotspot_sigmask(Thread* thread) { 577 578 //Save caller's signal mask before setting VM signal mask 579 sigset_t caller_sigmask; 580 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 581 582 OSThread* osthread = thread->osthread(); 583 osthread->set_caller_sigmask(caller_sigmask); 584 585 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 586 587 if (!ReduceSignalUsage) { 588 if (thread->is_VM_thread()) { 589 // Only the VM thread handles BREAK_SIGNAL ... 590 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 591 } else { 592 // ... all other threads block BREAK_SIGNAL 593 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 594 } 595 } 596 } 597 598 ////////////////////////////////////////////////////////////////////////////// 599 // detecting pthread library 600 601 void os::Linux::libpthread_init() { 602 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 603 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 604 // generic name for earlier versions. 605 // Define macros here so we can build HotSpot on old systems. 606 # ifndef _CS_GNU_LIBC_VERSION 607 # define _CS_GNU_LIBC_VERSION 2 608 # endif 609 # ifndef _CS_GNU_LIBPTHREAD_VERSION 610 # define _CS_GNU_LIBPTHREAD_VERSION 3 611 # endif 612 613 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 614 if (n > 0) { 615 char *str = (char *)malloc(n, mtInternal); 616 confstr(_CS_GNU_LIBC_VERSION, str, n); 617 os::Linux::set_glibc_version(str); 618 } else { 619 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 620 static char _gnu_libc_version[32]; 621 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 622 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 623 os::Linux::set_glibc_version(_gnu_libc_version); 624 } 625 626 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 627 if (n > 0) { 628 char *str = (char *)malloc(n, mtInternal); 629 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 630 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 631 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 632 // is the case. LinuxThreads has a hard limit on max number of threads. 633 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 634 // On the other hand, NPTL does not have such a limit, sysconf() 635 // will return -1 and errno is not changed. Check if it is really NPTL. 636 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 637 strstr(str, "NPTL") && 638 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 639 free(str); 640 os::Linux::set_libpthread_version("linuxthreads"); 641 } else { 642 os::Linux::set_libpthread_version(str); 643 } 644 } else { 645 // glibc before 2.3.2 only has LinuxThreads. 646 os::Linux::set_libpthread_version("linuxthreads"); 647 } 648 649 if (strstr(libpthread_version(), "NPTL")) { 650 os::Linux::set_is_NPTL(); 651 } else { 652 os::Linux::set_is_LinuxThreads(); 653 } 654 655 // LinuxThreads have two flavors: floating-stack mode, which allows variable 656 // stack size; and fixed-stack mode. NPTL is always floating-stack. 657 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 658 os::Linux::set_is_floating_stack(); 659 } 660 } 661 662 ///////////////////////////////////////////////////////////////////////////// 663 // thread stack 664 665 // Force Linux kernel to expand current thread stack. If "bottom" is close 666 // to the stack guard, caller should block all signals. 667 // 668 // MAP_GROWSDOWN: 669 // A special mmap() flag that is used to implement thread stacks. It tells 670 // kernel that the memory region should extend downwards when needed. This 671 // allows early versions of LinuxThreads to only mmap the first few pages 672 // when creating a new thread. Linux kernel will automatically expand thread 673 // stack as needed (on page faults). 674 // 675 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 676 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 677 // region, it's hard to tell if the fault is due to a legitimate stack 678 // access or because of reading/writing non-exist memory (e.g. buffer 679 // overrun). As a rule, if the fault happens below current stack pointer, 680 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 681 // application (see Linux kernel fault.c). 682 // 683 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 684 // stack overflow detection. 685 // 686 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 687 // not use this flag. However, the stack of initial thread is not created 688 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 689 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 690 // and then attach the thread to JVM. 691 // 692 // To get around the problem and allow stack banging on Linux, we need to 693 // manually expand thread stack after receiving the SIGSEGV. 694 // 695 // There are two ways to expand thread stack to address "bottom", we used 696 // both of them in JVM before 1.5: 697 // 1. adjust stack pointer first so that it is below "bottom", and then 698 // touch "bottom" 699 // 2. mmap() the page in question 700 // 701 // Now alternate signal stack is gone, it's harder to use 2. For instance, 702 // if current sp is already near the lower end of page 101, and we need to 703 // call mmap() to map page 100, it is possible that part of the mmap() frame 704 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 705 // That will destroy the mmap() frame and cause VM to crash. 706 // 707 // The following code works by adjusting sp first, then accessing the "bottom" 708 // page to force a page fault. Linux kernel will then automatically expand the 709 // stack mapping. 710 // 711 // _expand_stack_to() assumes its frame size is less than page size, which 712 // should always be true if the function is not inlined. 713 714 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 715 #define NOINLINE 716 #else 717 #define NOINLINE __attribute__ ((noinline)) 718 #endif 719 720 static void _expand_stack_to(address bottom) NOINLINE; 721 722 static void _expand_stack_to(address bottom) { 723 address sp; 724 size_t size; 725 volatile char *p; 726 727 // Adjust bottom to point to the largest address within the same page, it 728 // gives us a one-page buffer if alloca() allocates slightly more memory. 729 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 730 bottom += os::Linux::page_size() - 1; 731 732 // sp might be slightly above current stack pointer; if that's the case, we 733 // will alloca() a little more space than necessary, which is OK. Don't use 734 // os::current_stack_pointer(), as its result can be slightly below current 735 // stack pointer, causing us to not alloca enough to reach "bottom". 736 sp = (address)&sp; 737 738 if (sp > bottom) { 739 size = sp - bottom; 740 p = (volatile char *)alloca(size); 741 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 742 p[0] = '\0'; 743 } 744 } 745 746 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 747 assert(t!=NULL, "just checking"); 748 assert(t->osthread()->expanding_stack(), "expand should be set"); 749 assert(t->stack_base() != NULL, "stack_base was not initialized"); 750 751 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 752 sigset_t mask_all, old_sigset; 753 sigfillset(&mask_all); 754 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 755 _expand_stack_to(addr); 756 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 757 return true; 758 } 759 return false; 760 } 761 762 ////////////////////////////////////////////////////////////////////////////// 763 // create new thread 764 765 static address highest_vm_reserved_address(); 766 767 // check if it's safe to start a new thread 768 static bool _thread_safety_check(Thread* thread) { 769 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 770 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 771 // Heap is mmap'ed at lower end of memory space. Thread stacks are 772 // allocated (MAP_FIXED) from high address space. Every thread stack 773 // occupies a fixed size slot (usually 2Mbytes, but user can change 774 // it to other values if they rebuild LinuxThreads). 775 // 776 // Problem with MAP_FIXED is that mmap() can still succeed even part of 777 // the memory region has already been mmap'ed. That means if we have too 778 // many threads and/or very large heap, eventually thread stack will 779 // collide with heap. 780 // 781 // Here we try to prevent heap/stack collision by comparing current 782 // stack bottom with the highest address that has been mmap'ed by JVM 783 // plus a safety margin for memory maps created by native code. 784 // 785 // This feature can be disabled by setting ThreadSafetyMargin to 0 786 // 787 if (ThreadSafetyMargin > 0) { 788 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 789 790 // not safe if our stack extends below the safety margin 791 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 792 } else { 793 return true; 794 } 795 } else { 796 // Floating stack LinuxThreads or NPTL: 797 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 798 // there's not enough space left, pthread_create() will fail. If we come 799 // here, that means enough space has been reserved for stack. 800 return true; 801 } 802 } 803 804 // Thread start routine for all newly created threads 805 static void *java_start(Thread *thread) { 806 // Try to randomize the cache line index of hot stack frames. 807 // This helps when threads of the same stack traces evict each other's 808 // cache lines. The threads can be either from the same JVM instance, or 809 // from different JVM instances. The benefit is especially true for 810 // processors with hyperthreading technology. 811 static int counter = 0; 812 int pid = os::current_process_id(); 813 alloca(((pid ^ counter++) & 7) * 128); 814 815 ThreadLocalStorage::set_thread(thread); 816 817 OSThread* osthread = thread->osthread(); 818 Monitor* sync = osthread->startThread_lock(); 819 820 // non floating stack LinuxThreads needs extra check, see above 821 if (!_thread_safety_check(thread)) { 822 // notify parent thread 823 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 824 osthread->set_state(ZOMBIE); 825 sync->notify_all(); 826 return NULL; 827 } 828 829 // thread_id is kernel thread id (similar to Solaris LWP id) 830 osthread->set_thread_id(os::Linux::gettid()); 831 832 if (UseNUMA) { 833 int lgrp_id = os::numa_get_group_id(); 834 if (lgrp_id != -1) { 835 thread->set_lgrp_id(lgrp_id); 836 } 837 } 838 // initialize signal mask for this thread 839 os::Linux::hotspot_sigmask(thread); 840 841 // initialize floating point control register 842 os::Linux::init_thread_fpu_state(); 843 844 // handshaking with parent thread 845 { 846 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 847 848 // notify parent thread 849 osthread->set_state(INITIALIZED); 850 sync->notify_all(); 851 852 // wait until os::start_thread() 853 while (osthread->get_state() == INITIALIZED) { 854 sync->wait(Mutex::_no_safepoint_check_flag); 855 } 856 } 857 858 // call one more level start routine 859 thread->run(); 860 861 return 0; 862 } 863 864 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 865 assert(thread->osthread() == NULL, "caller responsible"); 866 867 // Allocate the OSThread object 868 OSThread* osthread = new OSThread(NULL, NULL); 869 if (osthread == NULL) { 870 return false; 871 } 872 873 // set the correct thread state 874 osthread->set_thread_type(thr_type); 875 876 // Initial state is ALLOCATED but not INITIALIZED 877 osthread->set_state(ALLOCATED); 878 879 thread->set_osthread(osthread); 880 881 // init thread attributes 882 pthread_attr_t attr; 883 pthread_attr_init(&attr); 884 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 885 886 // stack size 887 if (os::Linux::supports_variable_stack_size()) { 888 // calculate stack size if it's not specified by caller 889 if (stack_size == 0) { 890 stack_size = os::Linux::default_stack_size(thr_type); 891 892 switch (thr_type) { 893 case os::java_thread: 894 // Java threads use ThreadStackSize which default value can be 895 // changed with the flag -Xss 896 assert (JavaThread::stack_size_at_create() > 0, "this should be set"); 897 stack_size = JavaThread::stack_size_at_create(); 898 break; 899 case os::compiler_thread: 900 if (CompilerThreadStackSize > 0) { 901 stack_size = (size_t)(CompilerThreadStackSize * K); 902 break; 903 } // else fall through: 904 // use VMThreadStackSize if CompilerThreadStackSize is not defined 905 case os::vm_thread: 906 case os::pgc_thread: 907 case os::cgc_thread: 908 case os::watcher_thread: 909 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 910 break; 911 } 912 } 913 914 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 915 pthread_attr_setstacksize(&attr, stack_size); 916 } else { 917 // let pthread_create() pick the default value. 918 } 919 920 // glibc guard page 921 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 922 923 ThreadState state; 924 925 { 926 // Serialize thread creation if we are running with fixed stack LinuxThreads 927 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 928 if (lock) { 929 os::Linux::createThread_lock()->lock_without_safepoint_check(); 930 } 931 932 pthread_t tid; 933 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 934 935 pthread_attr_destroy(&attr); 936 937 if (ret != 0) { 938 if (PrintMiscellaneous && (Verbose || WizardMode)) { 939 perror("pthread_create()"); 940 } 941 // Need to clean up stuff we've allocated so far 942 thread->set_osthread(NULL); 943 delete osthread; 944 if (lock) os::Linux::createThread_lock()->unlock(); 945 return false; 946 } 947 948 // Store pthread info into the OSThread 949 osthread->set_pthread_id(tid); 950 951 // Wait until child thread is either initialized or aborted 952 { 953 Monitor* sync_with_child = osthread->startThread_lock(); 954 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 955 while ((state = osthread->get_state()) == ALLOCATED) { 956 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 957 } 958 } 959 960 if (lock) { 961 os::Linux::createThread_lock()->unlock(); 962 } 963 } 964 965 // Aborted due to thread limit being reached 966 if (state == ZOMBIE) { 967 thread->set_osthread(NULL); 968 delete osthread; 969 return false; 970 } 971 972 // The thread is returned suspended (in state INITIALIZED), 973 // and is started higher up in the call chain 974 assert(state == INITIALIZED, "race condition"); 975 return true; 976 } 977 978 ///////////////////////////////////////////////////////////////////////////// 979 // attach existing thread 980 981 // bootstrap the main thread 982 bool os::create_main_thread(JavaThread* thread) { 983 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 984 return create_attached_thread(thread); 985 } 986 987 bool os::create_attached_thread(JavaThread* thread) { 988 #ifdef ASSERT 989 thread->verify_not_published(); 990 #endif 991 992 // Allocate the OSThread object 993 OSThread* osthread = new OSThread(NULL, NULL); 994 995 if (osthread == NULL) { 996 return false; 997 } 998 999 // Store pthread info into the OSThread 1000 osthread->set_thread_id(os::Linux::gettid()); 1001 osthread->set_pthread_id(::pthread_self()); 1002 1003 // initialize floating point control register 1004 os::Linux::init_thread_fpu_state(); 1005 1006 // Initial thread state is RUNNABLE 1007 osthread->set_state(RUNNABLE); 1008 1009 thread->set_osthread(osthread); 1010 1011 if (UseNUMA) { 1012 int lgrp_id = os::numa_get_group_id(); 1013 if (lgrp_id != -1) { 1014 thread->set_lgrp_id(lgrp_id); 1015 } 1016 } 1017 1018 if (os::Linux::is_initial_thread()) { 1019 // If current thread is initial thread, its stack is mapped on demand, 1020 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 1021 // the entire stack region to avoid SEGV in stack banging. 1022 // It is also useful to get around the heap-stack-gap problem on SuSE 1023 // kernel (see 4821821 for details). We first expand stack to the top 1024 // of yellow zone, then enable stack yellow zone (order is significant, 1025 // enabling yellow zone first will crash JVM on SuSE Linux), so there 1026 // is no gap between the last two virtual memory regions. 1027 1028 JavaThread *jt = (JavaThread *)thread; 1029 address addr = jt->stack_yellow_zone_base(); 1030 assert(addr != NULL, "initialization problem?"); 1031 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 1032 1033 osthread->set_expanding_stack(); 1034 os::Linux::manually_expand_stack(jt, addr); 1035 osthread->clear_expanding_stack(); 1036 } 1037 1038 // initialize signal mask for this thread 1039 // and save the caller's signal mask 1040 os::Linux::hotspot_sigmask(thread); 1041 1042 return true; 1043 } 1044 1045 void os::pd_start_thread(Thread* thread) { 1046 OSThread * osthread = thread->osthread(); 1047 assert(osthread->get_state() != INITIALIZED, "just checking"); 1048 Monitor* sync_with_child = osthread->startThread_lock(); 1049 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 1050 sync_with_child->notify(); 1051 } 1052 1053 // Free Linux resources related to the OSThread 1054 void os::free_thread(OSThread* osthread) { 1055 assert(osthread != NULL, "osthread not set"); 1056 1057 if (Thread::current()->osthread() == osthread) { 1058 // Restore caller's signal mask 1059 sigset_t sigmask = osthread->caller_sigmask(); 1060 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1061 } 1062 1063 delete osthread; 1064 } 1065 1066 ////////////////////////////////////////////////////////////////////////////// 1067 // thread local storage 1068 1069 int os::allocate_thread_local_storage() { 1070 pthread_key_t key; 1071 int rslt = pthread_key_create(&key, NULL); 1072 assert(rslt == 0, "cannot allocate thread local storage"); 1073 return (int)key; 1074 } 1075 1076 // Note: This is currently not used by VM, as we don't destroy TLS key 1077 // on VM exit. 1078 void os::free_thread_local_storage(int index) { 1079 int rslt = pthread_key_delete((pthread_key_t)index); 1080 assert(rslt == 0, "invalid index"); 1081 } 1082 1083 void os::thread_local_storage_at_put(int index, void* value) { 1084 int rslt = pthread_setspecific((pthread_key_t)index, value); 1085 assert(rslt == 0, "pthread_setspecific failed"); 1086 } 1087 1088 extern "C" Thread* get_thread() { 1089 return ThreadLocalStorage::thread(); 1090 } 1091 1092 ////////////////////////////////////////////////////////////////////////////// 1093 // initial thread 1094 1095 // Check if current thread is the initial thread, similar to Solaris thr_main. 1096 bool os::Linux::is_initial_thread(void) { 1097 char dummy; 1098 // If called before init complete, thread stack bottom will be null. 1099 // Can be called if fatal error occurs before initialization. 1100 if (initial_thread_stack_bottom() == NULL) return false; 1101 assert(initial_thread_stack_bottom() != NULL && 1102 initial_thread_stack_size() != 0, 1103 "os::init did not locate initial thread's stack region"); 1104 if ((address)&dummy >= initial_thread_stack_bottom() && 1105 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1106 return true; 1107 else return false; 1108 } 1109 1110 // Find the virtual memory area that contains addr 1111 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1112 FILE *fp = fopen("/proc/self/maps", "r"); 1113 if (fp) { 1114 address low, high; 1115 while (!feof(fp)) { 1116 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1117 if (low <= addr && addr < high) { 1118 if (vma_low) *vma_low = low; 1119 if (vma_high) *vma_high = high; 1120 fclose (fp); 1121 return true; 1122 } 1123 } 1124 for (;;) { 1125 int ch = fgetc(fp); 1126 if (ch == EOF || ch == (int)'\n') break; 1127 } 1128 } 1129 fclose(fp); 1130 } 1131 return false; 1132 } 1133 1134 // Locate initial thread stack. This special handling of initial thread stack 1135 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1136 // bogus value for initial thread. 1137 void os::Linux::capture_initial_stack(size_t max_size) { 1138 // stack size is the easy part, get it from RLIMIT_STACK 1139 size_t stack_size; 1140 struct rlimit rlim; 1141 getrlimit(RLIMIT_STACK, &rlim); 1142 stack_size = rlim.rlim_cur; 1143 1144 // 6308388: a bug in ld.so will relocate its own .data section to the 1145 // lower end of primordial stack; reduce ulimit -s value a little bit 1146 // so we won't install guard page on ld.so's data section. 1147 stack_size -= 2 * page_size(); 1148 1149 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1150 // 7.1, in both cases we will get 2G in return value. 1151 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1152 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1153 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1154 // in case other parts in glibc still assumes 2M max stack size. 1155 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1156 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1157 if (stack_size > 2 * K * K IA64_ONLY(*2)) 1158 stack_size = 2 * K * K IA64_ONLY(*2); 1159 // Try to figure out where the stack base (top) is. This is harder. 1160 // 1161 // When an application is started, glibc saves the initial stack pointer in 1162 // a global variable "__libc_stack_end", which is then used by system 1163 // libraries. __libc_stack_end should be pretty close to stack top. The 1164 // variable is available since the very early days. However, because it is 1165 // a private interface, it could disappear in the future. 1166 // 1167 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1168 // to __libc_stack_end, it is very close to stack top, but isn't the real 1169 // stack top. Note that /proc may not exist if VM is running as a chroot 1170 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1171 // /proc/<pid>/stat could change in the future (though unlikely). 1172 // 1173 // We try __libc_stack_end first. If that doesn't work, look for 1174 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1175 // as a hint, which should work well in most cases. 1176 1177 uintptr_t stack_start; 1178 1179 // try __libc_stack_end first 1180 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1181 if (p && *p) { 1182 stack_start = *p; 1183 } else { 1184 // see if we can get the start_stack field from /proc/self/stat 1185 FILE *fp; 1186 int pid; 1187 char state; 1188 int ppid; 1189 int pgrp; 1190 int session; 1191 int nr; 1192 int tpgrp; 1193 unsigned long flags; 1194 unsigned long minflt; 1195 unsigned long cminflt; 1196 unsigned long majflt; 1197 unsigned long cmajflt; 1198 unsigned long utime; 1199 unsigned long stime; 1200 long cutime; 1201 long cstime; 1202 long prio; 1203 long nice; 1204 long junk; 1205 long it_real; 1206 uintptr_t start; 1207 uintptr_t vsize; 1208 intptr_t rss; 1209 uintptr_t rsslim; 1210 uintptr_t scodes; 1211 uintptr_t ecode; 1212 int i; 1213 1214 // Figure what the primordial thread stack base is. Code is inspired 1215 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1216 // followed by command name surrounded by parentheses, state, etc. 1217 char stat[2048]; 1218 int statlen; 1219 1220 fp = fopen("/proc/self/stat", "r"); 1221 if (fp) { 1222 statlen = fread(stat, 1, 2047, fp); 1223 stat[statlen] = '\0'; 1224 fclose(fp); 1225 1226 // Skip pid and the command string. Note that we could be dealing with 1227 // weird command names, e.g. user could decide to rename java launcher 1228 // to "java 1.4.2 :)", then the stat file would look like 1229 // 1234 (java 1.4.2 :)) R ... ... 1230 // We don't really need to know the command string, just find the last 1231 // occurrence of ")" and then start parsing from there. See bug 4726580. 1232 char * s = strrchr(stat, ')'); 1233 1234 i = 0; 1235 if (s) { 1236 // Skip blank chars 1237 do s++; while (isspace(*s)); 1238 1239 #define _UFM UINTX_FORMAT 1240 #define _DFM INTX_FORMAT 1241 1242 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1243 /* 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 */ 1244 i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld " _UFM _UFM _DFM _UFM _UFM _UFM _UFM, 1245 &state, /* 3 %c */ 1246 &ppid, /* 4 %d */ 1247 &pgrp, /* 5 %d */ 1248 &session, /* 6 %d */ 1249 &nr, /* 7 %d */ 1250 &tpgrp, /* 8 %d */ 1251 &flags, /* 9 %lu */ 1252 &minflt, /* 10 %lu */ 1253 &cminflt, /* 11 %lu */ 1254 &majflt, /* 12 %lu */ 1255 &cmajflt, /* 13 %lu */ 1256 &utime, /* 14 %lu */ 1257 &stime, /* 15 %lu */ 1258 &cutime, /* 16 %ld */ 1259 &cstime, /* 17 %ld */ 1260 &prio, /* 18 %ld */ 1261 &nice, /* 19 %ld */ 1262 &junk, /* 20 %ld */ 1263 &it_real, /* 21 %ld */ 1264 &start, /* 22 UINTX_FORMAT */ 1265 &vsize, /* 23 UINTX_FORMAT */ 1266 &rss, /* 24 INTX_FORMAT */ 1267 &rsslim, /* 25 UINTX_FORMAT */ 1268 &scodes, /* 26 UINTX_FORMAT */ 1269 &ecode, /* 27 UINTX_FORMAT */ 1270 &stack_start); /* 28 UINTX_FORMAT */ 1271 } 1272 1273 #undef _UFM 1274 #undef _DFM 1275 1276 if (i != 28 - 2) { 1277 assert(false, "Bad conversion from /proc/self/stat"); 1278 // product mode - assume we are the initial thread, good luck in the 1279 // embedded case. 1280 warning("Can't detect initial thread stack location - bad conversion"); 1281 stack_start = (uintptr_t) &rlim; 1282 } 1283 } else { 1284 // For some reason we can't open /proc/self/stat (for example, running on 1285 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1286 // most cases, so don't abort: 1287 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1288 stack_start = (uintptr_t) &rlim; 1289 } 1290 } 1291 1292 // Now we have a pointer (stack_start) very close to the stack top, the 1293 // next thing to do is to figure out the exact location of stack top. We 1294 // can find out the virtual memory area that contains stack_start by 1295 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1296 // and its upper limit is the real stack top. (again, this would fail if 1297 // running inside chroot, because /proc may not exist.) 1298 1299 uintptr_t stack_top; 1300 address low, high; 1301 if (find_vma((address)stack_start, &low, &high)) { 1302 // success, "high" is the true stack top. (ignore "low", because initial 1303 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1304 stack_top = (uintptr_t)high; 1305 } else { 1306 // failed, likely because /proc/self/maps does not exist 1307 warning("Can't detect initial thread stack location - find_vma failed"); 1308 // best effort: stack_start is normally within a few pages below the real 1309 // stack top, use it as stack top, and reduce stack size so we won't put 1310 // guard page outside stack. 1311 stack_top = stack_start; 1312 stack_size -= 16 * page_size(); 1313 } 1314 1315 // stack_top could be partially down the page so align it 1316 stack_top = align_size_up(stack_top, page_size()); 1317 1318 if (max_size && stack_size > max_size) { 1319 _initial_thread_stack_size = max_size; 1320 } else { 1321 _initial_thread_stack_size = stack_size; 1322 } 1323 1324 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1325 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1326 } 1327 1328 //////////////////////////////////////////////////////////////////////////////// 1329 // time support 1330 1331 // Time since start-up in seconds to a fine granularity. 1332 // Used by VMSelfDestructTimer and the MemProfiler. 1333 double os::elapsedTime() { 1334 1335 return (double)(os::elapsed_counter()) * 0.000001; 1336 } 1337 1338 jlong os::elapsed_counter() { 1339 timeval time; 1340 int status = gettimeofday(&time, NULL); 1341 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count; 1342 } 1343 1344 jlong os::elapsed_frequency() { 1345 return (1000 * 1000); 1346 } 1347 1348 bool os::supports_vtime() { return true; } 1349 bool os::enable_vtime() { return false; } 1350 bool os::vtime_enabled() { return false; } 1351 1352 double os::elapsedVTime() { 1353 struct rusage usage; 1354 int retval = getrusage(RUSAGE_THREAD, &usage); 1355 if (retval == 0) { 1356 return (double) (usage.ru_utime.tv_sec + usage.ru_stime.tv_sec) + (double) (usage.ru_utime.tv_usec + usage.ru_stime.tv_usec) / (1000 * 1000); 1357 } else { 1358 // better than nothing, but not much 1359 return elapsedTime(); 1360 } 1361 } 1362 1363 jlong os::javaTimeMillis() { 1364 timeval time; 1365 int status = gettimeofday(&time, NULL); 1366 assert(status != -1, "linux error"); 1367 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1368 } 1369 1370 #ifndef CLOCK_MONOTONIC 1371 #define CLOCK_MONOTONIC (1) 1372 #endif 1373 1374 void os::Linux::clock_init() { 1375 // we do dlopen's in this particular order due to bug in linux 1376 // dynamical loader (see 6348968) leading to crash on exit 1377 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1378 if (handle == NULL) { 1379 handle = dlopen("librt.so", RTLD_LAZY); 1380 } 1381 1382 if (handle) { 1383 int (*clock_getres_func)(clockid_t, struct timespec*) = 1384 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1385 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1386 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1387 if (clock_getres_func && clock_gettime_func) { 1388 // See if monotonic clock is supported by the kernel. Note that some 1389 // early implementations simply return kernel jiffies (updated every 1390 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1391 // for nano time (though the monotonic property is still nice to have). 1392 // It's fixed in newer kernels, however clock_getres() still returns 1393 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1394 // resolution for now. Hopefully as people move to new kernels, this 1395 // won't be a problem. 1396 struct timespec res; 1397 struct timespec tp; 1398 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1399 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1400 // yes, monotonic clock is supported 1401 _clock_gettime = clock_gettime_func; 1402 } else { 1403 // close librt if there is no monotonic clock 1404 dlclose(handle); 1405 } 1406 } 1407 } 1408 } 1409 1410 #ifndef SYS_clock_getres 1411 1412 #if defined(IA32) || defined(AMD64) 1413 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1414 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1415 #else 1416 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1417 #define sys_clock_getres(x,y) -1 1418 #endif 1419 1420 #else 1421 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1422 #endif 1423 1424 void os::Linux::fast_thread_clock_init() { 1425 if (!UseLinuxPosixThreadCPUClocks) { 1426 return; 1427 } 1428 clockid_t clockid; 1429 struct timespec tp; 1430 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1431 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1432 1433 // Switch to using fast clocks for thread cpu time if 1434 // the sys_clock_getres() returns 0 error code. 1435 // Note, that some kernels may support the current thread 1436 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1437 // returned by the pthread_getcpuclockid(). 1438 // If the fast Posix clocks are supported then the sys_clock_getres() 1439 // must return at least tp.tv_sec == 0 which means a resolution 1440 // better than 1 sec. This is extra check for reliability. 1441 1442 if(pthread_getcpuclockid_func && 1443 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1444 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1445 1446 _supports_fast_thread_cpu_time = true; 1447 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1448 } 1449 } 1450 1451 jlong os::javaTimeNanos() { 1452 if (Linux::supports_monotonic_clock()) { 1453 struct timespec tp; 1454 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1455 assert(status == 0, "gettime error"); 1456 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1457 return result; 1458 } else { 1459 timeval time; 1460 int status = gettimeofday(&time, NULL); 1461 assert(status != -1, "linux error"); 1462 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1463 return 1000 * usecs; 1464 } 1465 } 1466 1467 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1468 if (Linux::supports_monotonic_clock()) { 1469 info_ptr->max_value = ALL_64_BITS; 1470 1471 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1472 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1473 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1474 } else { 1475 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1476 info_ptr->max_value = ALL_64_BITS; 1477 1478 // gettimeofday is a real time clock so it skips 1479 info_ptr->may_skip_backward = true; 1480 info_ptr->may_skip_forward = true; 1481 } 1482 1483 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1484 } 1485 1486 // Return the real, user, and system times in seconds from an 1487 // arbitrary fixed point in the past. 1488 bool os::getTimesSecs(double* process_real_time, 1489 double* process_user_time, 1490 double* process_system_time) { 1491 struct tms ticks; 1492 clock_t real_ticks = times(&ticks); 1493 1494 if (real_ticks == (clock_t) (-1)) { 1495 return false; 1496 } else { 1497 double ticks_per_second = (double) clock_tics_per_sec; 1498 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1499 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1500 *process_real_time = ((double) real_ticks) / ticks_per_second; 1501 1502 return true; 1503 } 1504 } 1505 1506 1507 char * os::local_time_string(char *buf, size_t buflen) { 1508 struct tm t; 1509 time_t long_time; 1510 time(&long_time); 1511 localtime_r(&long_time, &t); 1512 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1513 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1514 t.tm_hour, t.tm_min, t.tm_sec); 1515 return buf; 1516 } 1517 1518 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1519 return localtime_r(clock, res); 1520 } 1521 1522 //////////////////////////////////////////////////////////////////////////////// 1523 // runtime exit support 1524 1525 // Note: os::shutdown() might be called very early during initialization, or 1526 // called from signal handler. Before adding something to os::shutdown(), make 1527 // sure it is async-safe and can handle partially initialized VM. 1528 void os::shutdown() { 1529 1530 // allow PerfMemory to attempt cleanup of any persistent resources 1531 perfMemory_exit(); 1532 1533 // needs to remove object in file system 1534 AttachListener::abort(); 1535 1536 // flush buffered output, finish log files 1537 ostream_abort(); 1538 1539 // Check for abort hook 1540 abort_hook_t abort_hook = Arguments::abort_hook(); 1541 if (abort_hook != NULL) { 1542 abort_hook(); 1543 } 1544 1545 } 1546 1547 // Note: os::abort() might be called very early during initialization, or 1548 // called from signal handler. Before adding something to os::abort(), make 1549 // sure it is async-safe and can handle partially initialized VM. 1550 void os::abort(bool dump_core) { 1551 os::shutdown(); 1552 if (dump_core) { 1553 #ifndef PRODUCT 1554 fdStream out(defaultStream::output_fd()); 1555 out.print_raw("Current thread is "); 1556 char buf[16]; 1557 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1558 out.print_raw_cr(buf); 1559 out.print_raw_cr("Dumping core ..."); 1560 #endif 1561 ::abort(); // dump core 1562 } 1563 1564 ::exit(1); 1565 } 1566 1567 // Die immediately, no exit hook, no abort hook, no cleanup. 1568 void os::die() { 1569 // _exit() on LinuxThreads only kills current thread 1570 ::abort(); 1571 } 1572 1573 // unused on linux for now. 1574 void os::set_error_file(const char *logfile) {} 1575 1576 1577 // This method is a copy of JDK's sysGetLastErrorString 1578 // from src/solaris/hpi/src/system_md.c 1579 1580 size_t os::lasterror(char *buf, size_t len) { 1581 1582 if (errno == 0) return 0; 1583 1584 const char *s = ::strerror(errno); 1585 size_t n = ::strlen(s); 1586 if (n >= len) { 1587 n = len - 1; 1588 } 1589 ::strncpy(buf, s, n); 1590 buf[n] = '\0'; 1591 return n; 1592 } 1593 1594 intx os::current_thread_id() { return (intx)pthread_self(); } 1595 int os::current_process_id() { 1596 1597 // Under the old linux thread library, linux gives each thread 1598 // its own process id. Because of this each thread will return 1599 // a different pid if this method were to return the result 1600 // of getpid(2). Linux provides no api that returns the pid 1601 // of the launcher thread for the vm. This implementation 1602 // returns a unique pid, the pid of the launcher thread 1603 // that starts the vm 'process'. 1604 1605 // Under the NPTL, getpid() returns the same pid as the 1606 // launcher thread rather than a unique pid per thread. 1607 // Use gettid() if you want the old pre NPTL behaviour. 1608 1609 // if you are looking for the result of a call to getpid() that 1610 // returns a unique pid for the calling thread, then look at the 1611 // OSThread::thread_id() method in osThread_linux.hpp file 1612 1613 return (int)(_initial_pid ? _initial_pid : getpid()); 1614 } 1615 1616 // DLL functions 1617 1618 const char* os::dll_file_extension() { return ".so"; } 1619 1620 // This must be hard coded because it's the system's temporary 1621 // directory not the java application's temp directory, ala java.io.tmpdir. 1622 const char* os::get_temp_directory() { return "/tmp"; } 1623 1624 static bool file_exists(const char* filename) { 1625 struct stat statbuf; 1626 if (filename == NULL || strlen(filename) == 0) { 1627 return false; 1628 } 1629 return os::stat(filename, &statbuf) == 0; 1630 } 1631 1632 bool os::dll_build_name(char* buffer, size_t buflen, 1633 const char* pname, const char* fname) { 1634 bool retval = false; 1635 // Copied from libhpi 1636 const size_t pnamelen = pname ? strlen(pname) : 0; 1637 1638 // Return error on buffer overflow. 1639 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1640 return retval; 1641 } 1642 1643 if (pnamelen == 0) { 1644 snprintf(buffer, buflen, "lib%s.so", fname); 1645 retval = true; 1646 } else if (strchr(pname, *os::path_separator()) != NULL) { 1647 int n; 1648 char** pelements = split_path(pname, &n); 1649 if (pelements == NULL) { 1650 return false; 1651 } 1652 for (int i = 0 ; i < n ; i++) { 1653 // Really shouldn't be NULL, but check can't hurt 1654 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1655 continue; // skip the empty path values 1656 } 1657 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1658 if (file_exists(buffer)) { 1659 retval = true; 1660 break; 1661 } 1662 } 1663 // release the storage 1664 for (int i = 0 ; i < n ; i++) { 1665 if (pelements[i] != NULL) { 1666 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal); 1667 } 1668 } 1669 if (pelements != NULL) { 1670 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal); 1671 } 1672 } else { 1673 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1674 retval = true; 1675 } 1676 return retval; 1677 } 1678 1679 // check if addr is inside libjvm.so 1680 bool os::address_is_in_vm(address addr) { 1681 static address libjvm_base_addr; 1682 Dl_info dlinfo; 1683 1684 if (libjvm_base_addr == NULL) { 1685 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1686 libjvm_base_addr = (address)dlinfo.dli_fbase; 1687 } 1688 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1689 } 1690 1691 if (dladdr((void *)addr, &dlinfo) != 0) { 1692 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1693 } 1694 1695 return false; 1696 } 1697 1698 bool os::dll_address_to_function_name(address addr, char *buf, 1699 int buflen, int *offset) { 1700 // buf is not optional, but offset is optional 1701 assert(buf != NULL, "sanity check"); 1702 1703 Dl_info dlinfo; 1704 1705 if (dladdr((void*)addr, &dlinfo) != 0) { 1706 // see if we have a matching symbol 1707 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1708 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1709 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1710 } 1711 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1712 return true; 1713 } 1714 // no matching symbol so try for just file info 1715 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1716 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1717 buf, buflen, offset, dlinfo.dli_fname)) { 1718 return true; 1719 } 1720 } 1721 } 1722 1723 buf[0] = '\0'; 1724 if (offset != NULL) *offset = -1; 1725 return false; 1726 } 1727 1728 struct _address_to_library_name { 1729 address addr; // input : memory address 1730 size_t buflen; // size of fname 1731 char* fname; // output: library name 1732 address base; // library base addr 1733 }; 1734 1735 static int address_to_library_name_callback(struct dl_phdr_info *info, 1736 size_t size, void *data) { 1737 int i; 1738 bool found = false; 1739 address libbase = NULL; 1740 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1741 1742 // iterate through all loadable segments 1743 for (i = 0; i < info->dlpi_phnum; i++) { 1744 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1745 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1746 // base address of a library is the lowest address of its loaded 1747 // segments. 1748 if (libbase == NULL || libbase > segbase) { 1749 libbase = segbase; 1750 } 1751 // see if 'addr' is within current segment 1752 if (segbase <= d->addr && 1753 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1754 found = true; 1755 } 1756 } 1757 } 1758 1759 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1760 // so dll_address_to_library_name() can fall through to use dladdr() which 1761 // can figure out executable name from argv[0]. 1762 if (found && info->dlpi_name && info->dlpi_name[0]) { 1763 d->base = libbase; 1764 if (d->fname) { 1765 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1766 } 1767 return 1; 1768 } 1769 return 0; 1770 } 1771 1772 bool os::dll_address_to_library_name(address addr, char* buf, 1773 int buflen, int* offset) { 1774 // buf is not optional, but offset is optional 1775 assert(buf != NULL, "sanity check"); 1776 1777 Dl_info dlinfo; 1778 struct _address_to_library_name data; 1779 1780 // There is a bug in old glibc dladdr() implementation that it could resolve 1781 // to wrong library name if the .so file has a base address != NULL. Here 1782 // we iterate through the program headers of all loaded libraries to find 1783 // out which library 'addr' really belongs to. This workaround can be 1784 // removed once the minimum requirement for glibc is moved to 2.3.x. 1785 data.addr = addr; 1786 data.fname = buf; 1787 data.buflen = buflen; 1788 data.base = NULL; 1789 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1790 1791 if (rslt) { 1792 // buf already contains library name 1793 if (offset) *offset = addr - data.base; 1794 return true; 1795 } 1796 if (dladdr((void*)addr, &dlinfo) != 0) { 1797 if (dlinfo.dli_fname != NULL) { 1798 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1799 } 1800 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1801 *offset = addr - (address)dlinfo.dli_fbase; 1802 } 1803 return true; 1804 } 1805 1806 buf[0] = '\0'; 1807 if (offset) *offset = -1; 1808 return false; 1809 } 1810 1811 // Loads .dll/.so and 1812 // in case of error it checks if .dll/.so was built for the 1813 // same architecture as Hotspot is running on 1814 1815 1816 // Remember the stack's state. The Linux dynamic linker will change 1817 // the stack to 'executable' at most once, so we must safepoint only once. 1818 bool os::Linux::_stack_is_executable = false; 1819 1820 // VM operation that loads a library. This is necessary if stack protection 1821 // of the Java stacks can be lost during loading the library. If we 1822 // do not stop the Java threads, they can stack overflow before the stacks 1823 // are protected again. 1824 class VM_LinuxDllLoad: public VM_Operation { 1825 private: 1826 const char *_filename; 1827 char *_ebuf; 1828 int _ebuflen; 1829 void *_lib; 1830 public: 1831 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1832 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1833 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1834 void doit() { 1835 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1836 os::Linux::_stack_is_executable = true; 1837 } 1838 void* loaded_library() { return _lib; } 1839 }; 1840 1841 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1842 { 1843 void * result = NULL; 1844 bool load_attempted = false; 1845 1846 // Check whether the library to load might change execution rights 1847 // of the stack. If they are changed, the protection of the stack 1848 // guard pages will be lost. We need a safepoint to fix this. 1849 // 1850 // See Linux man page execstack(8) for more info. 1851 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1852 ElfFile ef(filename); 1853 if (!ef.specifies_noexecstack()) { 1854 if (!is_init_completed()) { 1855 os::Linux::_stack_is_executable = true; 1856 // This is OK - No Java threads have been created yet, and hence no 1857 // stack guard pages to fix. 1858 // 1859 // This should happen only when you are building JDK7 using a very 1860 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1861 // 1862 // Dynamic loader will make all stacks executable after 1863 // this function returns, and will not do that again. 1864 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1865 } else { 1866 warning("You have loaded library %s which might have disabled stack guard. " 1867 "The VM will try to fix the stack guard now.\n" 1868 "It's highly recommended that you fix the library with " 1869 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1870 filename); 1871 1872 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1873 JavaThread *jt = JavaThread::current(); 1874 if (jt->thread_state() != _thread_in_native) { 1875 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1876 // that requires ExecStack. Cannot enter safe point. Let's give up. 1877 warning("Unable to fix stack guard. Giving up."); 1878 } else { 1879 if (!LoadExecStackDllInVMThread) { 1880 // This is for the case where the DLL has an static 1881 // constructor function that executes JNI code. We cannot 1882 // load such DLLs in the VMThread. 1883 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1884 } 1885 1886 ThreadInVMfromNative tiv(jt); 1887 debug_only(VMNativeEntryWrapper vew;) 1888 1889 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1890 VMThread::execute(&op); 1891 if (LoadExecStackDllInVMThread) { 1892 result = op.loaded_library(); 1893 } 1894 load_attempted = true; 1895 } 1896 } 1897 } 1898 } 1899 1900 if (!load_attempted) { 1901 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1902 } 1903 1904 if (result != NULL) { 1905 // Successful loading 1906 return result; 1907 } 1908 1909 Elf32_Ehdr elf_head; 1910 int diag_msg_max_length=ebuflen-strlen(ebuf); 1911 char* diag_msg_buf=ebuf+strlen(ebuf); 1912 1913 if (diag_msg_max_length==0) { 1914 // No more space in ebuf for additional diagnostics message 1915 return NULL; 1916 } 1917 1918 1919 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1920 1921 if (file_descriptor < 0) { 1922 // Can't open library, report dlerror() message 1923 return NULL; 1924 } 1925 1926 bool failed_to_read_elf_head= 1927 (sizeof(elf_head)!= 1928 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1929 1930 ::close(file_descriptor); 1931 if (failed_to_read_elf_head) { 1932 // file i/o error - report dlerror() msg 1933 return NULL; 1934 } 1935 1936 typedef struct { 1937 Elf32_Half code; // Actual value as defined in elf.h 1938 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1939 char elf_class; // 32 or 64 bit 1940 char endianess; // MSB or LSB 1941 char* name; // String representation 1942 } arch_t; 1943 1944 #ifndef EM_486 1945 #define EM_486 6 /* Intel 80486 */ 1946 #endif 1947 1948 static const arch_t arch_array[]={ 1949 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1950 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1951 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1952 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1953 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1954 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1955 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1956 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1957 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1958 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1959 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1960 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1961 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1962 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1963 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1964 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1965 }; 1966 1967 #if (defined IA32) 1968 static Elf32_Half running_arch_code=EM_386; 1969 #elif (defined AMD64) 1970 static Elf32_Half running_arch_code=EM_X86_64; 1971 #elif (defined IA64) 1972 static Elf32_Half running_arch_code=EM_IA_64; 1973 #elif (defined __sparc) && (defined _LP64) 1974 static Elf32_Half running_arch_code=EM_SPARCV9; 1975 #elif (defined __sparc) && (!defined _LP64) 1976 static Elf32_Half running_arch_code=EM_SPARC; 1977 #elif (defined __powerpc64__) 1978 static Elf32_Half running_arch_code=EM_PPC64; 1979 #elif (defined __powerpc__) 1980 static Elf32_Half running_arch_code=EM_PPC; 1981 #elif (defined ARM) 1982 static Elf32_Half running_arch_code=EM_ARM; 1983 #elif (defined S390) 1984 static Elf32_Half running_arch_code=EM_S390; 1985 #elif (defined ALPHA) 1986 static Elf32_Half running_arch_code=EM_ALPHA; 1987 #elif (defined MIPSEL) 1988 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1989 #elif (defined PARISC) 1990 static Elf32_Half running_arch_code=EM_PARISC; 1991 #elif (defined MIPS) 1992 static Elf32_Half running_arch_code=EM_MIPS; 1993 #elif (defined M68K) 1994 static Elf32_Half running_arch_code=EM_68K; 1995 #else 1996 #error Method os::dll_load requires that one of following is defined:\ 1997 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1998 #endif 1999 2000 // Identify compatability class for VM's architecture and library's architecture 2001 // Obtain string descriptions for architectures 2002 2003 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 2004 int running_arch_index=-1; 2005 2006 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 2007 if (running_arch_code == arch_array[i].code) { 2008 running_arch_index = i; 2009 } 2010 if (lib_arch.code == arch_array[i].code) { 2011 lib_arch.compat_class = arch_array[i].compat_class; 2012 lib_arch.name = arch_array[i].name; 2013 } 2014 } 2015 2016 assert(running_arch_index != -1, 2017 "Didn't find running architecture code (running_arch_code) in arch_array"); 2018 if (running_arch_index == -1) { 2019 // Even though running architecture detection failed 2020 // we may still continue with reporting dlerror() message 2021 return NULL; 2022 } 2023 2024 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 2025 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 2026 return NULL; 2027 } 2028 2029 #ifndef S390 2030 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 2031 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 2032 return NULL; 2033 } 2034 #endif // !S390 2035 2036 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 2037 if ( lib_arch.name!=NULL ) { 2038 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2039 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 2040 lib_arch.name, arch_array[running_arch_index].name); 2041 } else { 2042 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2043 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 2044 lib_arch.code, 2045 arch_array[running_arch_index].name); 2046 } 2047 } 2048 2049 return NULL; 2050 } 2051 2052 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) { 2053 void * result = ::dlopen(filename, RTLD_LAZY); 2054 if (result == NULL) { 2055 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2056 ebuf[ebuflen-1] = '\0'; 2057 } 2058 return result; 2059 } 2060 2061 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) { 2062 void * result = NULL; 2063 if (LoadExecStackDllInVMThread) { 2064 result = dlopen_helper(filename, ebuf, ebuflen); 2065 } 2066 2067 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2068 // library that requires an executable stack, or which does not have this 2069 // stack attribute set, dlopen changes the stack attribute to executable. The 2070 // read protection of the guard pages gets lost. 2071 // 2072 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2073 // may have been queued at the same time. 2074 2075 if (!_stack_is_executable) { 2076 JavaThread *jt = Threads::first(); 2077 2078 while (jt) { 2079 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2080 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2081 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2082 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2083 warning("Attempt to reguard stack yellow zone failed."); 2084 } 2085 } 2086 jt = jt->next(); 2087 } 2088 } 2089 2090 return result; 2091 } 2092 2093 /* 2094 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2095 * chances are you might want to run the generated bits against glibc-2.0 2096 * libdl.so, so always use locking for any version of glibc. 2097 */ 2098 void* os::dll_lookup(void* handle, const char* name) { 2099 pthread_mutex_lock(&dl_mutex); 2100 void* res = dlsym(handle, name); 2101 pthread_mutex_unlock(&dl_mutex); 2102 return res; 2103 } 2104 2105 2106 static bool _print_ascii_file(const char* filename, outputStream* st) { 2107 int fd = ::open(filename, O_RDONLY); 2108 if (fd == -1) { 2109 return false; 2110 } 2111 2112 char buf[32]; 2113 int bytes; 2114 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2115 st->print_raw(buf, bytes); 2116 } 2117 2118 ::close(fd); 2119 2120 return true; 2121 } 2122 2123 void os::print_dll_info(outputStream *st) { 2124 st->print_cr("Dynamic libraries:"); 2125 2126 char fname[32]; 2127 pid_t pid = os::Linux::gettid(); 2128 2129 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2130 2131 if (!_print_ascii_file(fname, st)) { 2132 st->print("Can not get library information for pid = %d\n", pid); 2133 } 2134 } 2135 2136 void os::print_os_info_brief(outputStream* st) { 2137 os::Linux::print_distro_info(st); 2138 2139 os::Posix::print_uname_info(st); 2140 2141 os::Linux::print_libversion_info(st); 2142 2143 } 2144 2145 void os::print_os_info(outputStream* st) { 2146 st->print("OS:"); 2147 2148 os::Linux::print_distro_info(st); 2149 2150 os::Posix::print_uname_info(st); 2151 2152 // Print warning if unsafe chroot environment detected 2153 if (unsafe_chroot_detected) { 2154 st->print("WARNING!! "); 2155 st->print_cr(unstable_chroot_error); 2156 } 2157 2158 os::Linux::print_libversion_info(st); 2159 2160 os::Posix::print_rlimit_info(st); 2161 2162 os::Posix::print_load_average(st); 2163 2164 os::Linux::print_full_memory_info(st); 2165 } 2166 2167 // Try to identify popular distros. 2168 // Most Linux distributions have /etc/XXX-release file, which contains 2169 // the OS version string. Some have more than one /etc/XXX-release file 2170 // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.), 2171 // so the order is important. 2172 void os::Linux::print_distro_info(outputStream* st) { 2173 if (!_print_ascii_file("/etc/mandrake-release", st) && 2174 !_print_ascii_file("/etc/sun-release", st) && 2175 !_print_ascii_file("/etc/redhat-release", st) && 2176 !_print_ascii_file("/etc/SuSE-release", st) && 2177 !_print_ascii_file("/etc/turbolinux-release", st) && 2178 !_print_ascii_file("/etc/gentoo-release", st) && 2179 !_print_ascii_file("/etc/debian_version", st) && 2180 !_print_ascii_file("/etc/ltib-release", st) && 2181 !_print_ascii_file("/etc/angstrom-version", st)) { 2182 st->print("Linux"); 2183 } 2184 st->cr(); 2185 } 2186 2187 void os::Linux::print_libversion_info(outputStream* st) { 2188 // libc, pthread 2189 st->print("libc:"); 2190 st->print(os::Linux::glibc_version()); st->print(" "); 2191 st->print(os::Linux::libpthread_version()); st->print(" "); 2192 if (os::Linux::is_LinuxThreads()) { 2193 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2194 } 2195 st->cr(); 2196 } 2197 2198 void os::Linux::print_full_memory_info(outputStream* st) { 2199 st->print("\n/proc/meminfo:\n"); 2200 _print_ascii_file("/proc/meminfo", st); 2201 st->cr(); 2202 } 2203 2204 void os::print_memory_info(outputStream* st) { 2205 2206 st->print("Memory:"); 2207 st->print(" %dk page", os::vm_page_size()>>10); 2208 2209 // values in struct sysinfo are "unsigned long" 2210 struct sysinfo si; 2211 sysinfo(&si); 2212 2213 st->print(", physical " UINT64_FORMAT "k", 2214 os::physical_memory() >> 10); 2215 st->print("(" UINT64_FORMAT "k free)", 2216 os::available_memory() >> 10); 2217 st->print(", swap " UINT64_FORMAT "k", 2218 ((jlong)si.totalswap * si.mem_unit) >> 10); 2219 st->print("(" UINT64_FORMAT "k free)", 2220 ((jlong)si.freeswap * si.mem_unit) >> 10); 2221 st->cr(); 2222 } 2223 2224 void os::pd_print_cpu_info(outputStream* st) { 2225 st->print("\n/proc/cpuinfo:\n"); 2226 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2227 st->print(" <Not Available>"); 2228 } 2229 st->cr(); 2230 } 2231 2232 // Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific 2233 // but they're the same for all the linux arch that we support 2234 // and they're the same for solaris but there's no common place to put this. 2235 const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR", 2236 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG", 2237 "ILL_COPROC", "ILL_BADSTK" }; 2238 2239 const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV", 2240 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES", 2241 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" }; 2242 2243 const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" }; 2244 2245 const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" }; 2246 2247 void os::print_siginfo(outputStream* st, void* siginfo) { 2248 st->print("siginfo:"); 2249 2250 const int buflen = 100; 2251 char buf[buflen]; 2252 siginfo_t *si = (siginfo_t*)siginfo; 2253 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen)); 2254 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) { 2255 st->print("si_errno=%s", buf); 2256 } else { 2257 st->print("si_errno=%d", si->si_errno); 2258 } 2259 const int c = si->si_code; 2260 assert(c > 0, "unexpected si_code"); 2261 switch (si->si_signo) { 2262 case SIGILL: 2263 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]); 2264 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2265 break; 2266 case SIGFPE: 2267 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]); 2268 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2269 break; 2270 case SIGSEGV: 2271 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]); 2272 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2273 break; 2274 case SIGBUS: 2275 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]); 2276 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2277 break; 2278 default: 2279 st->print(", si_code=%d", si->si_code); 2280 // no si_addr 2281 } 2282 2283 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2284 UseSharedSpaces) { 2285 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2286 if (mapinfo->is_in_shared_space(si->si_addr)) { 2287 st->print("\n\nError accessing class data sharing archive." \ 2288 " Mapped file inaccessible during execution, " \ 2289 " possible disk/network problem."); 2290 } 2291 } 2292 st->cr(); 2293 } 2294 2295 2296 static void print_signal_handler(outputStream* st, int sig, 2297 char* buf, size_t buflen); 2298 2299 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2300 st->print_cr("Signal Handlers:"); 2301 print_signal_handler(st, SIGSEGV, buf, buflen); 2302 print_signal_handler(st, SIGBUS , buf, buflen); 2303 print_signal_handler(st, SIGFPE , buf, buflen); 2304 print_signal_handler(st, SIGPIPE, buf, buflen); 2305 print_signal_handler(st, SIGXFSZ, buf, buflen); 2306 print_signal_handler(st, SIGILL , buf, buflen); 2307 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2308 print_signal_handler(st, SR_signum, buf, buflen); 2309 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2310 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2311 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2312 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2313 } 2314 2315 static char saved_jvm_path[MAXPATHLEN] = {0}; 2316 2317 // Find the full path to the current module, libjvm.so 2318 void os::jvm_path(char *buf, jint buflen) { 2319 // Error checking. 2320 if (buflen < MAXPATHLEN) { 2321 assert(false, "must use a large-enough buffer"); 2322 buf[0] = '\0'; 2323 return; 2324 } 2325 // Lazy resolve the path to current module. 2326 if (saved_jvm_path[0] != 0) { 2327 strcpy(buf, saved_jvm_path); 2328 return; 2329 } 2330 2331 char dli_fname[MAXPATHLEN]; 2332 bool ret = dll_address_to_library_name( 2333 CAST_FROM_FN_PTR(address, os::jvm_path), 2334 dli_fname, sizeof(dli_fname), NULL); 2335 assert(ret, "cannot locate libjvm"); 2336 char *rp = NULL; 2337 if (ret && dli_fname[0] != '\0') { 2338 rp = realpath(dli_fname, buf); 2339 } 2340 if (rp == NULL) 2341 return; 2342 2343 if (Arguments::created_by_gamma_launcher()) { 2344 // Support for the gamma launcher. Typical value for buf is 2345 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at 2346 // the right place in the string, then assume we are installed in a JDK and 2347 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix 2348 // up the path so it looks like libjvm.so is installed there (append a 2349 // fake suffix hotspot/libjvm.so). 2350 const char *p = buf + strlen(buf) - 1; 2351 for (int count = 0; p > buf && count < 5; ++count) { 2352 for (--p; p > buf && *p != '/'; --p) 2353 /* empty */ ; 2354 } 2355 2356 if (strncmp(p, "/jre/lib/", 9) != 0) { 2357 // Look for JAVA_HOME in the environment. 2358 char* java_home_var = ::getenv("JAVA_HOME"); 2359 if (java_home_var != NULL && java_home_var[0] != 0) { 2360 char* jrelib_p; 2361 int len; 2362 2363 // Check the current module name "libjvm.so". 2364 p = strrchr(buf, '/'); 2365 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2366 2367 rp = realpath(java_home_var, buf); 2368 if (rp == NULL) 2369 return; 2370 2371 // determine if this is a legacy image or modules image 2372 // modules image doesn't have "jre" subdirectory 2373 len = strlen(buf); 2374 jrelib_p = buf + len; 2375 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2376 if (0 != access(buf, F_OK)) { 2377 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2378 } 2379 2380 if (0 == access(buf, F_OK)) { 2381 // Use current module name "libjvm.so" 2382 len = strlen(buf); 2383 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2384 } else { 2385 // Go back to path of .so 2386 rp = realpath(dli_fname, buf); 2387 if (rp == NULL) 2388 return; 2389 } 2390 } 2391 } 2392 } 2393 2394 strcpy(saved_jvm_path, buf); 2395 } 2396 2397 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2398 // no prefix required, not even "_" 2399 } 2400 2401 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2402 // no suffix required 2403 } 2404 2405 //////////////////////////////////////////////////////////////////////////////// 2406 // sun.misc.Signal support 2407 2408 static volatile jint sigint_count = 0; 2409 2410 static void 2411 UserHandler(int sig, void *siginfo, void *context) { 2412 // 4511530 - sem_post is serialized and handled by the manager thread. When 2413 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2414 // don't want to flood the manager thread with sem_post requests. 2415 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2416 return; 2417 2418 // Ctrl-C is pressed during error reporting, likely because the error 2419 // handler fails to abort. Let VM die immediately. 2420 if (sig == SIGINT && is_error_reported()) { 2421 os::die(); 2422 } 2423 2424 os::signal_notify(sig); 2425 } 2426 2427 void* os::user_handler() { 2428 return CAST_FROM_FN_PTR(void*, UserHandler); 2429 } 2430 2431 class Semaphore : public StackObj { 2432 public: 2433 Semaphore(); 2434 ~Semaphore(); 2435 void signal(); 2436 void wait(); 2437 bool trywait(); 2438 bool timedwait(unsigned int sec, int nsec); 2439 private: 2440 sem_t _semaphore; 2441 }; 2442 2443 2444 Semaphore::Semaphore() { 2445 sem_init(&_semaphore, 0, 0); 2446 } 2447 2448 Semaphore::~Semaphore() { 2449 sem_destroy(&_semaphore); 2450 } 2451 2452 void Semaphore::signal() { 2453 sem_post(&_semaphore); 2454 } 2455 2456 void Semaphore::wait() { 2457 sem_wait(&_semaphore); 2458 } 2459 2460 bool Semaphore::trywait() { 2461 return sem_trywait(&_semaphore) == 0; 2462 } 2463 2464 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2465 struct timespec ts; 2466 unpackTime(&ts, false, (sec * NANOSECS_PER_SEC) + nsec); 2467 2468 while (1) { 2469 int result = sem_timedwait(&_semaphore, &ts); 2470 if (result == 0) { 2471 return true; 2472 } else if (errno == EINTR) { 2473 continue; 2474 } else if (errno == ETIMEDOUT) { 2475 return false; 2476 } else { 2477 return false; 2478 } 2479 } 2480 } 2481 2482 extern "C" { 2483 typedef void (*sa_handler_t)(int); 2484 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2485 } 2486 2487 void* os::signal(int signal_number, void* handler) { 2488 struct sigaction sigAct, oldSigAct; 2489 2490 sigfillset(&(sigAct.sa_mask)); 2491 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2492 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2493 2494 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2495 // -1 means registration failed 2496 return (void *)-1; 2497 } 2498 2499 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2500 } 2501 2502 void os::signal_raise(int signal_number) { 2503 ::raise(signal_number); 2504 } 2505 2506 /* 2507 * The following code is moved from os.cpp for making this 2508 * code platform specific, which it is by its very nature. 2509 */ 2510 2511 // Will be modified when max signal is changed to be dynamic 2512 int os::sigexitnum_pd() { 2513 return NSIG; 2514 } 2515 2516 // a counter for each possible signal value 2517 static volatile jint pending_signals[NSIG+1] = { 0 }; 2518 2519 // Linux(POSIX) specific hand shaking semaphore. 2520 static sem_t sig_sem; 2521 static Semaphore sr_semaphore; 2522 2523 void os::signal_init_pd() { 2524 // Initialize signal structures 2525 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2526 2527 // Initialize signal semaphore 2528 ::sem_init(&sig_sem, 0, 0); 2529 } 2530 2531 void os::signal_notify(int sig) { 2532 Atomic::inc(&pending_signals[sig]); 2533 ::sem_post(&sig_sem); 2534 } 2535 2536 static int check_pending_signals(bool wait) { 2537 Atomic::store(0, &sigint_count); 2538 for (;;) { 2539 for (int i = 0; i < NSIG + 1; i++) { 2540 jint n = pending_signals[i]; 2541 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2542 return i; 2543 } 2544 } 2545 if (!wait) { 2546 return -1; 2547 } 2548 JavaThread *thread = JavaThread::current(); 2549 ThreadBlockInVM tbivm(thread); 2550 2551 bool threadIsSuspended; 2552 do { 2553 thread->set_suspend_equivalent(); 2554 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2555 ::sem_wait(&sig_sem); 2556 2557 // were we externally suspended while we were waiting? 2558 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2559 if (threadIsSuspended) { 2560 // 2561 // The semaphore has been incremented, but while we were waiting 2562 // another thread suspended us. We don't want to continue running 2563 // while suspended because that would surprise the thread that 2564 // suspended us. 2565 // 2566 ::sem_post(&sig_sem); 2567 2568 thread->java_suspend_self(); 2569 } 2570 } while (threadIsSuspended); 2571 } 2572 } 2573 2574 int os::signal_lookup() { 2575 return check_pending_signals(false); 2576 } 2577 2578 int os::signal_wait() { 2579 return check_pending_signals(true); 2580 } 2581 2582 //////////////////////////////////////////////////////////////////////////////// 2583 // Virtual Memory 2584 2585 int os::vm_page_size() { 2586 // Seems redundant as all get out 2587 assert(os::Linux::page_size() != -1, "must call os::init"); 2588 return os::Linux::page_size(); 2589 } 2590 2591 // Solaris allocates memory by pages. 2592 int os::vm_allocation_granularity() { 2593 assert(os::Linux::page_size() != -1, "must call os::init"); 2594 return os::Linux::page_size(); 2595 } 2596 2597 // Rationale behind this function: 2598 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2599 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2600 // samples for JITted code. Here we create private executable mapping over the code cache 2601 // and then we can use standard (well, almost, as mapping can change) way to provide 2602 // info for the reporting script by storing timestamp and location of symbol 2603 void linux_wrap_code(char* base, size_t size) { 2604 static volatile jint cnt = 0; 2605 2606 if (!UseOprofile) { 2607 return; 2608 } 2609 2610 char buf[PATH_MAX+1]; 2611 int num = Atomic::add(1, &cnt); 2612 2613 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2614 os::get_temp_directory(), os::current_process_id(), num); 2615 unlink(buf); 2616 2617 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2618 2619 if (fd != -1) { 2620 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2621 if (rv != (off_t)-1) { 2622 if (::write(fd, "", 1) == 1) { 2623 mmap(base, size, 2624 PROT_READ|PROT_WRITE|PROT_EXEC, 2625 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2626 } 2627 } 2628 ::close(fd); 2629 unlink(buf); 2630 } 2631 } 2632 2633 static bool recoverable_mmap_error(int err) { 2634 // See if the error is one we can let the caller handle. This 2635 // list of errno values comes from JBS-6843484. I can't find a 2636 // Linux man page that documents this specific set of errno 2637 // values so while this list currently matches Solaris, it may 2638 // change as we gain experience with this failure mode. 2639 switch (err) { 2640 case EBADF: 2641 case EINVAL: 2642 case ENOTSUP: 2643 // let the caller deal with these errors 2644 return true; 2645 2646 default: 2647 // Any remaining errors on this OS can cause our reserved mapping 2648 // to be lost. That can cause confusion where different data 2649 // structures think they have the same memory mapped. The worst 2650 // scenario is if both the VM and a library think they have the 2651 // same memory mapped. 2652 return false; 2653 } 2654 } 2655 2656 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2657 int err) { 2658 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2659 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2660 strerror(err), err); 2661 } 2662 2663 static void warn_fail_commit_memory(char* addr, size_t size, 2664 size_t alignment_hint, bool exec, 2665 int err) { 2666 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2667 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2668 alignment_hint, exec, strerror(err), err); 2669 } 2670 2671 // NOTE: Linux kernel does not really reserve the pages for us. 2672 // All it does is to check if there are enough free pages 2673 // left at the time of mmap(). This could be a potential 2674 // problem. 2675 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2676 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2677 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2678 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2679 if (res != (uintptr_t) MAP_FAILED) { 2680 if (UseNUMAInterleaving) { 2681 numa_make_global(addr, size); 2682 } 2683 return 0; 2684 } 2685 2686 int err = errno; // save errno from mmap() call above 2687 2688 if (!recoverable_mmap_error(err)) { 2689 warn_fail_commit_memory(addr, size, exec, err); 2690 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2691 } 2692 2693 return err; 2694 } 2695 2696 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2697 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2698 } 2699 2700 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2701 const char* mesg) { 2702 assert(mesg != NULL, "mesg must be specified"); 2703 int err = os::Linux::commit_memory_impl(addr, size, exec); 2704 if (err != 0) { 2705 // the caller wants all commit errors to exit with the specified mesg: 2706 warn_fail_commit_memory(addr, size, exec, err); 2707 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2708 } 2709 } 2710 2711 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2712 #ifndef MAP_HUGETLB 2713 #define MAP_HUGETLB 0x40000 2714 #endif 2715 2716 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2717 #ifndef MADV_HUGEPAGE 2718 #define MADV_HUGEPAGE 14 2719 #endif 2720 2721 int os::Linux::commit_memory_impl(char* addr, size_t size, 2722 size_t alignment_hint, bool exec) { 2723 int err = os::Linux::commit_memory_impl(addr, size, exec); 2724 if (err == 0) { 2725 realign_memory(addr, size, alignment_hint); 2726 } 2727 return err; 2728 } 2729 2730 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2731 bool exec) { 2732 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2733 } 2734 2735 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2736 size_t alignment_hint, bool exec, 2737 const char* mesg) { 2738 assert(mesg != NULL, "mesg must be specified"); 2739 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2740 if (err != 0) { 2741 // the caller wants all commit errors to exit with the specified mesg: 2742 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2743 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2744 } 2745 } 2746 2747 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2748 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2749 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2750 // be supported or the memory may already be backed by huge pages. 2751 ::madvise(addr, bytes, MADV_HUGEPAGE); 2752 } 2753 } 2754 2755 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2756 // This method works by doing an mmap over an existing mmaping and effectively discarding 2757 // the existing pages. However it won't work for SHM-based large pages that cannot be 2758 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2759 // small pages on top of the SHM segment. This method always works for small pages, so we 2760 // allow that in any case. 2761 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2762 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2763 } 2764 } 2765 2766 void os::numa_make_global(char *addr, size_t bytes) { 2767 Linux::numa_interleave_memory(addr, bytes); 2768 } 2769 2770 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2771 // bind policy to MPOL_PREFERRED for the current thread. 2772 #define USE_MPOL_PREFERRED 0 2773 2774 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2775 // To make NUMA and large pages more robust when both enabled, we need to ease 2776 // the requirements on where the memory should be allocated. MPOL_BIND is the 2777 // default policy and it will force memory to be allocated on the specified 2778 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2779 // the specified node, but will not force it. Using this policy will prevent 2780 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2781 // free large pages. 2782 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2783 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2784 } 2785 2786 bool os::numa_topology_changed() { return false; } 2787 2788 size_t os::numa_get_groups_num() { 2789 int max_node = Linux::numa_max_node(); 2790 return max_node > 0 ? max_node + 1 : 1; 2791 } 2792 2793 int os::numa_get_group_id() { 2794 int cpu_id = Linux::sched_getcpu(); 2795 if (cpu_id != -1) { 2796 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2797 if (lgrp_id != -1) { 2798 return lgrp_id; 2799 } 2800 } 2801 return 0; 2802 } 2803 2804 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2805 for (size_t i = 0; i < size; i++) { 2806 ids[i] = i; 2807 } 2808 return size; 2809 } 2810 2811 bool os::get_page_info(char *start, page_info* info) { 2812 return false; 2813 } 2814 2815 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2816 return end; 2817 } 2818 2819 2820 int os::Linux::sched_getcpu_syscall(void) { 2821 unsigned int cpu; 2822 int retval = -1; 2823 2824 #if defined(IA32) 2825 # ifndef SYS_getcpu 2826 # define SYS_getcpu 318 2827 # endif 2828 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2829 #elif defined(AMD64) 2830 // Unfortunately we have to bring all these macros here from vsyscall.h 2831 // to be able to compile on old linuxes. 2832 # define __NR_vgetcpu 2 2833 # define VSYSCALL_START (-10UL << 20) 2834 # define VSYSCALL_SIZE 1024 2835 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2836 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2837 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2838 retval = vgetcpu(&cpu, NULL, NULL); 2839 #endif 2840 2841 return (retval == -1) ? retval : cpu; 2842 } 2843 2844 // Something to do with the numa-aware allocator needs these symbols 2845 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2846 extern "C" JNIEXPORT void numa_error(char *where) { } 2847 extern "C" JNIEXPORT int fork1() { return fork(); } 2848 2849 2850 // If we are running with libnuma version > 2, then we should 2851 // be trying to use symbols with versions 1.1 2852 // If we are running with earlier version, which did not have symbol versions, 2853 // we should use the base version. 2854 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2855 void *f = dlvsym(handle, name, "libnuma_1.1"); 2856 if (f == NULL) { 2857 f = dlsym(handle, name); 2858 } 2859 return f; 2860 } 2861 2862 bool os::Linux::libnuma_init() { 2863 // sched_getcpu() should be in libc. 2864 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2865 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2866 2867 // If it's not, try a direct syscall. 2868 if (sched_getcpu() == -1) 2869 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall)); 2870 2871 if (sched_getcpu() != -1) { // Does it work? 2872 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2873 if (handle != NULL) { 2874 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2875 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2876 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2877 libnuma_dlsym(handle, "numa_max_node"))); 2878 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2879 libnuma_dlsym(handle, "numa_available"))); 2880 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2881 libnuma_dlsym(handle, "numa_tonode_memory"))); 2882 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2883 libnuma_dlsym(handle, "numa_interleave_memory"))); 2884 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2885 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2886 2887 2888 if (numa_available() != -1) { 2889 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2890 // Create a cpu -> node mapping 2891 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2892 rebuild_cpu_to_node_map(); 2893 return true; 2894 } 2895 } 2896 } 2897 return false; 2898 } 2899 2900 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2901 // The table is later used in get_node_by_cpu(). 2902 void os::Linux::rebuild_cpu_to_node_map() { 2903 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2904 // in libnuma (possible values are starting from 16, 2905 // and continuing up with every other power of 2, but less 2906 // than the maximum number of CPUs supported by kernel), and 2907 // is a subject to change (in libnuma version 2 the requirements 2908 // are more reasonable) we'll just hardcode the number they use 2909 // in the library. 2910 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2911 2912 size_t cpu_num = os::active_processor_count(); 2913 size_t cpu_map_size = NCPUS / BitsPerCLong; 2914 size_t cpu_map_valid_size = 2915 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2916 2917 cpu_to_node()->clear(); 2918 cpu_to_node()->at_grow(cpu_num - 1); 2919 size_t node_num = numa_get_groups_num(); 2920 2921 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2922 for (size_t i = 0; i < node_num; i++) { 2923 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2924 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2925 if (cpu_map[j] != 0) { 2926 for (size_t k = 0; k < BitsPerCLong; k++) { 2927 if (cpu_map[j] & (1UL << k)) { 2928 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2929 } 2930 } 2931 } 2932 } 2933 } 2934 } 2935 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal); 2936 } 2937 2938 int os::Linux::get_node_by_cpu(int cpu_id) { 2939 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2940 return cpu_to_node()->at(cpu_id); 2941 } 2942 return -1; 2943 } 2944 2945 GrowableArray<int>* os::Linux::_cpu_to_node; 2946 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2947 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2948 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2949 os::Linux::numa_available_func_t os::Linux::_numa_available; 2950 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2951 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2952 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2953 unsigned long* os::Linux::_numa_all_nodes; 2954 2955 bool os::pd_uncommit_memory(char* addr, size_t size) { 2956 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2957 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2958 return res != (uintptr_t) MAP_FAILED; 2959 } 2960 2961 // Linux uses a growable mapping for the stack, and if the mapping for 2962 // the stack guard pages is not removed when we detach a thread the 2963 // stack cannot grow beyond the pages where the stack guard was 2964 // mapped. If at some point later in the process the stack expands to 2965 // that point, the Linux kernel cannot expand the stack any further 2966 // because the guard pages are in the way, and a segfault occurs. 2967 // 2968 // However, it's essential not to split the stack region by unmapping 2969 // a region (leaving a hole) that's already part of the stack mapping, 2970 // so if the stack mapping has already grown beyond the guard pages at 2971 // the time we create them, we have to truncate the stack mapping. 2972 // So, we need to know the extent of the stack mapping when 2973 // create_stack_guard_pages() is called. 2974 2975 // Find the bounds of the stack mapping. Return true for success. 2976 // 2977 // We only need this for stacks that are growable: at the time of 2978 // writing thread stacks don't use growable mappings (i.e. those 2979 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 2980 // only applies to the main thread. 2981 2982 static 2983 bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) { 2984 2985 char buf[128]; 2986 int fd, sz; 2987 2988 if ((fd = ::open("/proc/self/maps", O_RDONLY)) < 0) { 2989 return false; 2990 } 2991 2992 const char kw[] = "[stack]"; 2993 const int kwlen = sizeof(kw)-1; 2994 2995 // Address part of /proc/self/maps couldn't be more than 128 bytes 2996 while ((sz = os::get_line_chars(fd, buf, sizeof(buf))) > 0) { 2997 if (sz > kwlen && ::memcmp(buf+sz-kwlen, kw, kwlen) == 0) { 2998 // Extract addresses 2999 if (sscanf(buf, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) { 3000 uintptr_t sp = (uintptr_t) __builtin_frame_address(0); 3001 if (sp >= *bottom && sp <= *top) { 3002 ::close(fd); 3003 return true; 3004 } 3005 } 3006 } 3007 } 3008 3009 ::close(fd); 3010 return false; 3011 } 3012 3013 3014 // If the (growable) stack mapping already extends beyond the point 3015 // where we're going to put our guard pages, truncate the mapping at 3016 // that point by munmap()ping it. This ensures that when we later 3017 // munmap() the guard pages we don't leave a hole in the stack 3018 // mapping. This only affects the main/initial thread, but guard 3019 // against future OS changes 3020 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3021 uintptr_t stack_extent, stack_base; 3022 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true); 3023 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) { 3024 assert(os::Linux::is_initial_thread(), 3025 "growable stack in non-initial thread"); 3026 if (stack_extent < (uintptr_t)addr) 3027 ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent); 3028 } 3029 3030 return os::commit_memory(addr, size, !ExecMem); 3031 } 3032 3033 // If this is a growable mapping, remove the guard pages entirely by 3034 // munmap()ping them. If not, just call uncommit_memory(). This only 3035 // affects the main/initial thread, but guard against future OS changes 3036 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3037 uintptr_t stack_extent, stack_base; 3038 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true); 3039 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) { 3040 assert(os::Linux::is_initial_thread(), 3041 "growable stack in non-initial thread"); 3042 3043 return ::munmap(addr, size) == 0; 3044 } 3045 3046 return os::uncommit_memory(addr, size); 3047 } 3048 3049 static address _highest_vm_reserved_address = NULL; 3050 3051 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3052 // at 'requested_addr'. If there are existing memory mappings at the same 3053 // location, however, they will be overwritten. If 'fixed' is false, 3054 // 'requested_addr' is only treated as a hint, the return value may or 3055 // may not start from the requested address. Unlike Linux mmap(), this 3056 // function returns NULL to indicate failure. 3057 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3058 char * addr; 3059 int flags; 3060 3061 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3062 if (fixed) { 3063 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3064 flags |= MAP_FIXED; 3065 } 3066 3067 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3068 // touch an uncommitted page. Otherwise, the read/write might 3069 // succeed if we have enough swap space to back the physical page. 3070 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3071 flags, -1, 0); 3072 3073 if (addr != MAP_FAILED) { 3074 // anon_mmap() should only get called during VM initialization, 3075 // don't need lock (actually we can skip locking even it can be called 3076 // from multiple threads, because _highest_vm_reserved_address is just a 3077 // hint about the upper limit of non-stack memory regions.) 3078 if ((address)addr + bytes > _highest_vm_reserved_address) { 3079 _highest_vm_reserved_address = (address)addr + bytes; 3080 } 3081 } 3082 3083 return addr == MAP_FAILED ? NULL : addr; 3084 } 3085 3086 // Don't update _highest_vm_reserved_address, because there might be memory 3087 // regions above addr + size. If so, releasing a memory region only creates 3088 // a hole in the address space, it doesn't help prevent heap-stack collision. 3089 // 3090 static int anon_munmap(char * addr, size_t size) { 3091 return ::munmap(addr, size) == 0; 3092 } 3093 3094 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3095 size_t alignment_hint) { 3096 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3097 } 3098 3099 bool os::pd_release_memory(char* addr, size_t size) { 3100 return anon_munmap(addr, size); 3101 } 3102 3103 static address highest_vm_reserved_address() { 3104 return _highest_vm_reserved_address; 3105 } 3106 3107 static bool linux_mprotect(char* addr, size_t size, int prot) { 3108 // Linux wants the mprotect address argument to be page aligned. 3109 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3110 3111 // According to SUSv3, mprotect() should only be used with mappings 3112 // established by mmap(), and mmap() always maps whole pages. Unaligned 3113 // 'addr' likely indicates problem in the VM (e.g. trying to change 3114 // protection of malloc'ed or statically allocated memory). Check the 3115 // caller if you hit this assert. 3116 assert(addr == bottom, "sanity check"); 3117 3118 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3119 return ::mprotect(bottom, size, prot) == 0; 3120 } 3121 3122 // Set protections specified 3123 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3124 bool is_committed) { 3125 unsigned int p = 0; 3126 switch (prot) { 3127 case MEM_PROT_NONE: p = PROT_NONE; break; 3128 case MEM_PROT_READ: p = PROT_READ; break; 3129 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3130 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3131 default: 3132 ShouldNotReachHere(); 3133 } 3134 // is_committed is unused. 3135 return linux_mprotect(addr, bytes, p); 3136 } 3137 3138 bool os::guard_memory(char* addr, size_t size) { 3139 return linux_mprotect(addr, size, PROT_NONE); 3140 } 3141 3142 bool os::unguard_memory(char* addr, size_t size) { 3143 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3144 } 3145 3146 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) { 3147 bool result = false; 3148 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3149 MAP_ANONYMOUS|MAP_PRIVATE, 3150 -1, 0); 3151 if (p != MAP_FAILED) { 3152 void *aligned_p = align_ptr_up(p, page_size); 3153 3154 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3155 3156 munmap(p, page_size * 2); 3157 } 3158 3159 if (warn && !result) { 3160 warning("TransparentHugePages is not supported by the operating system."); 3161 } 3162 3163 return result; 3164 } 3165 3166 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3167 bool result = false; 3168 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3169 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3170 -1, 0); 3171 3172 if (p != MAP_FAILED) { 3173 // We don't know if this really is a huge page or not. 3174 FILE *fp = fopen("/proc/self/maps", "r"); 3175 if (fp) { 3176 while (!feof(fp)) { 3177 char chars[257]; 3178 long x = 0; 3179 if (fgets(chars, sizeof(chars), fp)) { 3180 if (sscanf(chars, "%lx-%*x", &x) == 1 3181 && x == (long)p) { 3182 if (strstr (chars, "hugepage")) { 3183 result = true; 3184 break; 3185 } 3186 } 3187 } 3188 } 3189 fclose(fp); 3190 } 3191 munmap(p, page_size); 3192 } 3193 3194 if (warn && !result) { 3195 warning("HugeTLBFS is not supported by the operating system."); 3196 } 3197 3198 return result; 3199 } 3200 3201 /* 3202 * Set the coredump_filter bits to include largepages in core dump (bit 6) 3203 * 3204 * From the coredump_filter documentation: 3205 * 3206 * - (bit 0) anonymous private memory 3207 * - (bit 1) anonymous shared memory 3208 * - (bit 2) file-backed private memory 3209 * - (bit 3) file-backed shared memory 3210 * - (bit 4) ELF header pages in file-backed private memory areas (it is 3211 * effective only if the bit 2 is cleared) 3212 * - (bit 5) hugetlb private memory 3213 * - (bit 6) hugetlb shared memory 3214 */ 3215 static void set_coredump_filter(void) { 3216 FILE *f; 3217 long cdm; 3218 3219 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3220 return; 3221 } 3222 3223 if (fscanf(f, "%lx", &cdm) != 1) { 3224 fclose(f); 3225 return; 3226 } 3227 3228 rewind(f); 3229 3230 if ((cdm & LARGEPAGES_BIT) == 0) { 3231 cdm |= LARGEPAGES_BIT; 3232 fprintf(f, "%#lx", cdm); 3233 } 3234 3235 fclose(f); 3236 } 3237 3238 // Large page support 3239 3240 static size_t _large_page_size = 0; 3241 3242 size_t os::Linux::find_large_page_size() { 3243 size_t large_page_size = 0; 3244 3245 // large_page_size on Linux is used to round up heap size. x86 uses either 3246 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3247 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3248 // page as large as 256M. 3249 // 3250 // Here we try to figure out page size by parsing /proc/meminfo and looking 3251 // for a line with the following format: 3252 // Hugepagesize: 2048 kB 3253 // 3254 // If we can't determine the value (e.g. /proc is not mounted, or the text 3255 // format has been changed), we'll use the largest page size supported by 3256 // the processor. 3257 3258 #ifndef ZERO 3259 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3260 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3261 #endif // ZERO 3262 3263 FILE *fp = fopen("/proc/meminfo", "r"); 3264 if (fp) { 3265 while (!feof(fp)) { 3266 int x = 0; 3267 char buf[16]; 3268 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3269 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3270 large_page_size = x * K; 3271 break; 3272 } 3273 } else { 3274 // skip to next line 3275 for (;;) { 3276 int ch = fgetc(fp); 3277 if (ch == EOF || ch == (int)'\n') break; 3278 } 3279 } 3280 } 3281 fclose(fp); 3282 } 3283 3284 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3285 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3286 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3287 proper_unit_for_byte_size(large_page_size)); 3288 } 3289 3290 return large_page_size; 3291 } 3292 3293 size_t os::Linux::setup_large_page_size() { 3294 _large_page_size = Linux::find_large_page_size(); 3295 const size_t default_page_size = (size_t)Linux::page_size(); 3296 if (_large_page_size > default_page_size) { 3297 _page_sizes[0] = _large_page_size; 3298 _page_sizes[1] = default_page_size; 3299 _page_sizes[2] = 0; 3300 } 3301 3302 return _large_page_size; 3303 } 3304 3305 bool os::Linux::setup_large_page_type(size_t page_size) { 3306 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3307 FLAG_IS_DEFAULT(UseSHM) && 3308 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3309 // If UseLargePages is specified on the command line try all methods, 3310 // if it's default, then try only UseTransparentHugePages. 3311 if (FLAG_IS_DEFAULT(UseLargePages)) { 3312 UseTransparentHugePages = true; 3313 } else { 3314 UseHugeTLBFS = UseTransparentHugePages = UseSHM = true; 3315 } 3316 } 3317 3318 if (UseTransparentHugePages) { 3319 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3320 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3321 UseHugeTLBFS = false; 3322 UseSHM = false; 3323 return true; 3324 } 3325 UseTransparentHugePages = false; 3326 } 3327 3328 if (UseHugeTLBFS) { 3329 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3330 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3331 UseSHM = false; 3332 return true; 3333 } 3334 UseHugeTLBFS = false; 3335 } 3336 3337 return UseSHM; 3338 } 3339 3340 void os::large_page_init() { 3341 if (!UseLargePages) { 3342 UseHugeTLBFS = false; 3343 UseTransparentHugePages = false; 3344 UseSHM = false; 3345 return; 3346 } 3347 3348 size_t large_page_size = Linux::setup_large_page_size(); 3349 UseLargePages = Linux::setup_large_page_type(large_page_size); 3350 3351 set_coredump_filter(); 3352 } 3353 3354 #ifndef SHM_HUGETLB 3355 #define SHM_HUGETLB 04000 3356 #endif 3357 3358 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3359 // "exec" is passed in but not used. Creating the shared image for 3360 // the code cache doesn't have an SHM_X executable permission to check. 3361 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3362 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3363 3364 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3365 return NULL; // Fallback to small pages. 3366 } 3367 3368 key_t key = IPC_PRIVATE; 3369 char *addr; 3370 3371 bool warn_on_failure = UseLargePages && 3372 (!FLAG_IS_DEFAULT(UseLargePages) || 3373 !FLAG_IS_DEFAULT(UseSHM) || 3374 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 3375 ); 3376 char msg[128]; 3377 3378 // Create a large shared memory region to attach to based on size. 3379 // Currently, size is the total size of the heap 3380 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3381 if (shmid == -1) { 3382 // Possible reasons for shmget failure: 3383 // 1. shmmax is too small for Java heap. 3384 // > check shmmax value: cat /proc/sys/kernel/shmmax 3385 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3386 // 2. not enough large page memory. 3387 // > check available large pages: cat /proc/meminfo 3388 // > increase amount of large pages: 3389 // echo new_value > /proc/sys/vm/nr_hugepages 3390 // Note 1: different Linux may use different name for this property, 3391 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3392 // Note 2: it's possible there's enough physical memory available but 3393 // they are so fragmented after a long run that they can't 3394 // coalesce into large pages. Try to reserve large pages when 3395 // the system is still "fresh". 3396 if (warn_on_failure) { 3397 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3398 warning(msg); 3399 } 3400 return NULL; 3401 } 3402 3403 // attach to the region 3404 addr = (char*)shmat(shmid, req_addr, 0); 3405 int err = errno; 3406 3407 // Remove shmid. If shmat() is successful, the actual shared memory segment 3408 // will be deleted when it's detached by shmdt() or when the process 3409 // terminates. If shmat() is not successful this will remove the shared 3410 // segment immediately. 3411 shmctl(shmid, IPC_RMID, NULL); 3412 3413 if ((intptr_t)addr == -1) { 3414 if (warn_on_failure) { 3415 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3416 warning(msg); 3417 } 3418 return NULL; 3419 } 3420 3421 return addr; 3422 } 3423 3424 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) { 3425 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3426 3427 bool warn_on_failure = UseLargePages && 3428 (!FLAG_IS_DEFAULT(UseLargePages) || 3429 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3430 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3431 3432 if (warn_on_failure) { 3433 char msg[128]; 3434 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3435 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3436 warning(msg); 3437 } 3438 } 3439 3440 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) { 3441 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3442 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3443 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3444 3445 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3446 char* addr = (char*)::mmap(req_addr, bytes, prot, 3447 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3448 -1, 0); 3449 3450 if (addr == MAP_FAILED) { 3451 warn_on_large_pages_failure(req_addr, bytes, errno); 3452 return NULL; 3453 } 3454 3455 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3456 3457 return addr; 3458 } 3459 3460 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3461 size_t large_page_size = os::large_page_size(); 3462 3463 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3464 3465 // Allocate small pages. 3466 3467 char* start; 3468 if (req_addr != NULL) { 3469 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3470 assert(is_size_aligned(bytes, alignment), "Must be"); 3471 start = os::reserve_memory(bytes, req_addr); 3472 assert(start == NULL || start == req_addr, "Must be"); 3473 } else { 3474 start = os::reserve_memory_aligned(bytes, alignment); 3475 } 3476 3477 if (start == NULL) { 3478 return NULL; 3479 } 3480 3481 assert(is_ptr_aligned(start, alignment), "Must be"); 3482 3483 // os::reserve_memory_special will record this memory area. 3484 // Need to release it here to prevent overlapping reservations. 3485 MemTracker::record_virtual_memory_release((address)start, bytes); 3486 3487 char* end = start + bytes; 3488 3489 // Find the regions of the allocated chunk that can be promoted to large pages. 3490 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3491 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3492 3493 size_t lp_bytes = lp_end - lp_start; 3494 3495 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3496 3497 if (lp_bytes == 0) { 3498 // The mapped region doesn't even span the start and the end of a large page. 3499 // Fall back to allocate a non-special area. 3500 ::munmap(start, end - start); 3501 return NULL; 3502 } 3503 3504 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3505 3506 3507 void* result; 3508 3509 if (start != lp_start) { 3510 result = ::mmap(start, lp_start - start, prot, 3511 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3512 -1, 0); 3513 if (result == MAP_FAILED) { 3514 ::munmap(lp_start, end - lp_start); 3515 return NULL; 3516 } 3517 } 3518 3519 result = ::mmap(lp_start, lp_bytes, prot, 3520 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3521 -1, 0); 3522 if (result == MAP_FAILED) { 3523 warn_on_large_pages_failure(req_addr, bytes, errno); 3524 // If the mmap above fails, the large pages region will be unmapped and we 3525 // have regions before and after with small pages. Release these regions. 3526 // 3527 // | mapped | unmapped | mapped | 3528 // ^ ^ ^ ^ 3529 // start lp_start lp_end end 3530 // 3531 ::munmap(start, lp_start - start); 3532 ::munmap(lp_end, end - lp_end); 3533 return NULL; 3534 } 3535 3536 if (lp_end != end) { 3537 result = ::mmap(lp_end, end - lp_end, prot, 3538 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3539 -1, 0); 3540 if (result == MAP_FAILED) { 3541 ::munmap(start, lp_end - start); 3542 return NULL; 3543 } 3544 } 3545 3546 return start; 3547 } 3548 3549 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3550 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3551 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3552 assert(is_power_of_2(alignment), "Must be"); 3553 assert(is_power_of_2(os::large_page_size()), "Must be"); 3554 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3555 3556 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3557 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3558 } else { 3559 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3560 } 3561 } 3562 3563 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3564 assert(UseLargePages, "only for large pages"); 3565 3566 char* addr; 3567 if (UseSHM) { 3568 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3569 } else { 3570 assert(UseHugeTLBFS, "must be"); 3571 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3572 } 3573 3574 if (addr != NULL) { 3575 if (UseNUMAInterleaving) { 3576 numa_make_global(addr, bytes); 3577 } 3578 3579 // The memory is committed 3580 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, mtNone, CALLER_PC); 3581 } 3582 3583 return addr; 3584 } 3585 3586 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3587 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3588 return shmdt(base) == 0; 3589 } 3590 3591 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3592 return pd_release_memory(base, bytes); 3593 } 3594 3595 bool os::release_memory_special(char* base, size_t bytes) { 3596 assert(UseLargePages, "only for large pages"); 3597 3598 MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3599 3600 bool res; 3601 if (UseSHM) { 3602 res = os::Linux::release_memory_special_shm(base, bytes); 3603 } else { 3604 assert(UseHugeTLBFS, "must be"); 3605 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3606 } 3607 3608 if (res) { 3609 tkr.record((address)base, bytes); 3610 } else { 3611 tkr.discard(); 3612 } 3613 3614 return res; 3615 } 3616 3617 size_t os::large_page_size() { 3618 return _large_page_size; 3619 } 3620 3621 // With SysV SHM the entire memory region must be allocated as shared 3622 // memory. 3623 // HugeTLBFS allows application to commit large page memory on demand. 3624 // However, when committing memory with HugeTLBFS fails, the region 3625 // that was supposed to be committed will lose the old reservation 3626 // and allow other threads to steal that memory region. Because of this 3627 // behavior we can't commit HugeTLBFS memory. 3628 bool os::can_commit_large_page_memory() { 3629 return UseTransparentHugePages; 3630 } 3631 3632 bool os::can_execute_large_page_memory() { 3633 return UseTransparentHugePages || UseHugeTLBFS; 3634 } 3635 3636 // Reserve memory at an arbitrary address, only if that area is 3637 // available (and not reserved for something else). 3638 3639 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3640 const int max_tries = 10; 3641 char* base[max_tries]; 3642 size_t size[max_tries]; 3643 const size_t gap = 0x000000; 3644 3645 // Assert only that the size is a multiple of the page size, since 3646 // that's all that mmap requires, and since that's all we really know 3647 // about at this low abstraction level. If we need higher alignment, 3648 // we can either pass an alignment to this method or verify alignment 3649 // in one of the methods further up the call chain. See bug 5044738. 3650 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3651 3652 // Repeatedly allocate blocks until the block is allocated at the 3653 // right spot. Give up after max_tries. Note that reserve_memory() will 3654 // automatically update _highest_vm_reserved_address if the call is 3655 // successful. The variable tracks the highest memory address every reserved 3656 // by JVM. It is used to detect heap-stack collision if running with 3657 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3658 // space than needed, it could confuse the collision detecting code. To 3659 // solve the problem, save current _highest_vm_reserved_address and 3660 // calculate the correct value before return. 3661 address old_highest = _highest_vm_reserved_address; 3662 3663 // Linux mmap allows caller to pass an address as hint; give it a try first, 3664 // if kernel honors the hint then we can return immediately. 3665 char * addr = anon_mmap(requested_addr, bytes, false); 3666 if (addr == requested_addr) { 3667 return requested_addr; 3668 } 3669 3670 if (addr != NULL) { 3671 // mmap() is successful but it fails to reserve at the requested address 3672 anon_munmap(addr, bytes); 3673 } 3674 3675 int i; 3676 for (i = 0; i < max_tries; ++i) { 3677 base[i] = reserve_memory(bytes); 3678 3679 if (base[i] != NULL) { 3680 // Is this the block we wanted? 3681 if (base[i] == requested_addr) { 3682 size[i] = bytes; 3683 break; 3684 } 3685 3686 // Does this overlap the block we wanted? Give back the overlapped 3687 // parts and try again. 3688 3689 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3690 if (top_overlap >= 0 && top_overlap < bytes) { 3691 unmap_memory(base[i], top_overlap); 3692 base[i] += top_overlap; 3693 size[i] = bytes - top_overlap; 3694 } else { 3695 size_t bottom_overlap = base[i] + bytes - requested_addr; 3696 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3697 unmap_memory(requested_addr, bottom_overlap); 3698 size[i] = bytes - bottom_overlap; 3699 } else { 3700 size[i] = bytes; 3701 } 3702 } 3703 } 3704 } 3705 3706 // Give back the unused reserved pieces. 3707 3708 for (int j = 0; j < i; ++j) { 3709 if (base[j] != NULL) { 3710 unmap_memory(base[j], size[j]); 3711 } 3712 } 3713 3714 if (i < max_tries) { 3715 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3716 return requested_addr; 3717 } else { 3718 _highest_vm_reserved_address = old_highest; 3719 return NULL; 3720 } 3721 } 3722 3723 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3724 return ::read(fd, buf, nBytes); 3725 } 3726 3727 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation. 3728 // Solaris uses poll(), linux uses park(). 3729 // Poll() is likely a better choice, assuming that Thread.interrupt() 3730 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with 3731 // SIGSEGV, see 4355769. 3732 3733 int os::sleep(Thread* thread, jlong millis, bool interruptible) { 3734 assert(thread == Thread::current(), "thread consistency check"); 3735 3736 ParkEvent * const slp = thread->_SleepEvent ; 3737 slp->reset() ; 3738 OrderAccess::fence() ; 3739 3740 if (interruptible) { 3741 jlong prevtime = javaTimeNanos(); 3742 3743 for (;;) { 3744 if (os::is_interrupted(thread, true)) { 3745 return OS_INTRPT; 3746 } 3747 3748 jlong newtime = javaTimeNanos(); 3749 3750 if (newtime - prevtime < 0) { 3751 // time moving backwards, should only happen if no monotonic clock 3752 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3753 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3754 } else { 3755 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3756 } 3757 3758 if(millis <= 0) { 3759 return OS_OK; 3760 } 3761 3762 prevtime = newtime; 3763 3764 { 3765 assert(thread->is_Java_thread(), "sanity check"); 3766 JavaThread *jt = (JavaThread *) thread; 3767 ThreadBlockInVM tbivm(jt); 3768 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */); 3769 3770 jt->set_suspend_equivalent(); 3771 // cleared by handle_special_suspend_equivalent_condition() or 3772 // java_suspend_self() via check_and_wait_while_suspended() 3773 3774 slp->park(millis); 3775 3776 // were we externally suspended while we were waiting? 3777 jt->check_and_wait_while_suspended(); 3778 } 3779 } 3780 } else { 3781 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 3782 jlong prevtime = javaTimeNanos(); 3783 3784 for (;;) { 3785 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on 3786 // the 1st iteration ... 3787 jlong newtime = javaTimeNanos(); 3788 3789 if (newtime - prevtime < 0) { 3790 // time moving backwards, should only happen if no monotonic clock 3791 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3792 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3793 } else { 3794 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3795 } 3796 3797 if(millis <= 0) break ; 3798 3799 prevtime = newtime; 3800 slp->park(millis); 3801 } 3802 return OS_OK ; 3803 } 3804 } 3805 3806 int os::naked_sleep() { 3807 // %% make the sleep time an integer flag. for now use 1 millisec. 3808 return os::sleep(Thread::current(), 1, false); 3809 } 3810 3811 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3812 void os::infinite_sleep() { 3813 while (true) { // sleep forever ... 3814 ::sleep(100); // ... 100 seconds at a time 3815 } 3816 } 3817 3818 // Used to convert frequent JVM_Yield() to nops 3819 bool os::dont_yield() { 3820 return DontYieldALot; 3821 } 3822 3823 void os::yield() { 3824 sched_yield(); 3825 } 3826 3827 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 3828 3829 void os::yield_all(int attempts) { 3830 // Yields to all threads, including threads with lower priorities 3831 // Threads on Linux are all with same priority. The Solaris style 3832 // os::yield_all() with nanosleep(1ms) is not necessary. 3833 sched_yield(); 3834 } 3835 3836 // Called from the tight loops to possibly influence time-sharing heuristics 3837 void os::loop_breaker(int attempts) { 3838 os::yield_all(attempts); 3839 } 3840 3841 //////////////////////////////////////////////////////////////////////////////// 3842 // thread priority support 3843 3844 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3845 // only supports dynamic priority, static priority must be zero. For real-time 3846 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3847 // However, for large multi-threaded applications, SCHED_RR is not only slower 3848 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3849 // of 5 runs - Sep 2005). 3850 // 3851 // The following code actually changes the niceness of kernel-thread/LWP. It 3852 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3853 // not the entire user process, and user level threads are 1:1 mapped to kernel 3854 // threads. It has always been the case, but could change in the future. For 3855 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3856 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3857 3858 int os::java_to_os_priority[CriticalPriority + 1] = { 3859 19, // 0 Entry should never be used 3860 3861 4, // 1 MinPriority 3862 3, // 2 3863 2, // 3 3864 3865 1, // 4 3866 0, // 5 NormPriority 3867 -1, // 6 3868 3869 -2, // 7 3870 -3, // 8 3871 -4, // 9 NearMaxPriority 3872 3873 -5, // 10 MaxPriority 3874 3875 -5 // 11 CriticalPriority 3876 }; 3877 3878 static int prio_init() { 3879 if (ThreadPriorityPolicy == 1) { 3880 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3881 // if effective uid is not root. Perhaps, a more elegant way of doing 3882 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3883 if (geteuid() != 0) { 3884 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3885 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3886 } 3887 ThreadPriorityPolicy = 0; 3888 } 3889 } 3890 if (UseCriticalJavaThreadPriority) { 3891 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3892 } 3893 return 0; 3894 } 3895 3896 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3897 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 3898 3899 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3900 return (ret == 0) ? OS_OK : OS_ERR; 3901 } 3902 3903 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3904 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3905 *priority_ptr = java_to_os_priority[NormPriority]; 3906 return OS_OK; 3907 } 3908 3909 errno = 0; 3910 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3911 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3912 } 3913 3914 // Hint to the underlying OS that a task switch would not be good. 3915 // Void return because it's a hint and can fail. 3916 void os::hint_no_preempt() {} 3917 3918 //////////////////////////////////////////////////////////////////////////////// 3919 // suspend/resume support 3920 3921 // the low-level signal-based suspend/resume support is a remnant from the 3922 // old VM-suspension that used to be for java-suspension, safepoints etc, 3923 // within hotspot. Now there is a single use-case for this: 3924 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3925 // that runs in the watcher thread. 3926 // The remaining code is greatly simplified from the more general suspension 3927 // code that used to be used. 3928 // 3929 // The protocol is quite simple: 3930 // - suspend: 3931 // - sends a signal to the target thread 3932 // - polls the suspend state of the osthread using a yield loop 3933 // - target thread signal handler (SR_handler) sets suspend state 3934 // and blocks in sigsuspend until continued 3935 // - resume: 3936 // - sets target osthread state to continue 3937 // - sends signal to end the sigsuspend loop in the SR_handler 3938 // 3939 // Note that the SR_lock plays no role in this suspend/resume protocol. 3940 // 3941 3942 static void resume_clear_context(OSThread *osthread) { 3943 osthread->set_ucontext(NULL); 3944 osthread->set_siginfo(NULL); 3945 } 3946 3947 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 3948 osthread->set_ucontext(context); 3949 osthread->set_siginfo(siginfo); 3950 } 3951 3952 // 3953 // Handler function invoked when a thread's execution is suspended or 3954 // resumed. We have to be careful that only async-safe functions are 3955 // called here (Note: most pthread functions are not async safe and 3956 // should be avoided.) 3957 // 3958 // Note: sigwait() is a more natural fit than sigsuspend() from an 3959 // interface point of view, but sigwait() prevents the signal hander 3960 // from being run. libpthread would get very confused by not having 3961 // its signal handlers run and prevents sigwait()'s use with the 3962 // mutex granting granting signal. 3963 // 3964 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 3965 // 3966 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3967 // Save and restore errno to avoid confusing native code with EINTR 3968 // after sigsuspend. 3969 int old_errno = errno; 3970 3971 Thread* thread = Thread::current(); 3972 OSThread* osthread = thread->osthread(); 3973 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 3974 3975 os::SuspendResume::State current = osthread->sr.state(); 3976 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 3977 suspend_save_context(osthread, siginfo, context); 3978 3979 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 3980 os::SuspendResume::State state = osthread->sr.suspended(); 3981 if (state == os::SuspendResume::SR_SUSPENDED) { 3982 sigset_t suspend_set; // signals for sigsuspend() 3983 3984 // get current set of blocked signals and unblock resume signal 3985 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3986 sigdelset(&suspend_set, SR_signum); 3987 3988 sr_semaphore.signal(); 3989 // wait here until we are resumed 3990 while (1) { 3991 sigsuspend(&suspend_set); 3992 3993 os::SuspendResume::State result = osthread->sr.running(); 3994 if (result == os::SuspendResume::SR_RUNNING) { 3995 sr_semaphore.signal(); 3996 break; 3997 } 3998 } 3999 4000 } else if (state == os::SuspendResume::SR_RUNNING) { 4001 // request was cancelled, continue 4002 } else { 4003 ShouldNotReachHere(); 4004 } 4005 4006 resume_clear_context(osthread); 4007 } else if (current == os::SuspendResume::SR_RUNNING) { 4008 // request was cancelled, continue 4009 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 4010 // ignore 4011 } else { 4012 // ignore 4013 } 4014 4015 errno = old_errno; 4016 } 4017 4018 4019 static int SR_initialize() { 4020 struct sigaction act; 4021 char *s; 4022 /* Get signal number to use for suspend/resume */ 4023 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 4024 int sig = ::strtol(s, 0, 10); 4025 if (sig > 0 || sig < _NSIG) { 4026 SR_signum = sig; 4027 } 4028 } 4029 4030 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 4031 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 4032 4033 sigemptyset(&SR_sigset); 4034 sigaddset(&SR_sigset, SR_signum); 4035 4036 /* Set up signal handler for suspend/resume */ 4037 act.sa_flags = SA_RESTART|SA_SIGINFO; 4038 act.sa_handler = (void (*)(int)) SR_handler; 4039 4040 // SR_signum is blocked by default. 4041 // 4528190 - We also need to block pthread restart signal (32 on all 4042 // supported Linux platforms). Note that LinuxThreads need to block 4043 // this signal for all threads to work properly. So we don't have 4044 // to use hard-coded signal number when setting up the mask. 4045 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4046 4047 if (sigaction(SR_signum, &act, 0) == -1) { 4048 return -1; 4049 } 4050 4051 // Save signal flag 4052 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4053 return 0; 4054 } 4055 4056 static int sr_notify(OSThread* osthread) { 4057 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4058 assert_status(status == 0, status, "pthread_kill"); 4059 return status; 4060 } 4061 4062 // "Randomly" selected value for how long we want to spin 4063 // before bailing out on suspending a thread, also how often 4064 // we send a signal to a thread we want to resume 4065 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4066 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4067 4068 // returns true on success and false on error - really an error is fatal 4069 // but this seems the normal response to library errors 4070 static bool do_suspend(OSThread* osthread) { 4071 assert(osthread->sr.is_running(), "thread should be running"); 4072 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4073 4074 // mark as suspended and send signal 4075 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4076 // failed to switch, state wasn't running? 4077 ShouldNotReachHere(); 4078 return false; 4079 } 4080 4081 if (sr_notify(osthread) != 0) { 4082 ShouldNotReachHere(); 4083 } 4084 4085 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4086 while (true) { 4087 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4088 break; 4089 } else { 4090 // timeout 4091 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4092 if (cancelled == os::SuspendResume::SR_RUNNING) { 4093 return false; 4094 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4095 // make sure that we consume the signal on the semaphore as well 4096 sr_semaphore.wait(); 4097 break; 4098 } else { 4099 ShouldNotReachHere(); 4100 return false; 4101 } 4102 } 4103 } 4104 4105 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4106 return true; 4107 } 4108 4109 static void do_resume(OSThread* osthread) { 4110 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4111 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4112 4113 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4114 // failed to switch to WAKEUP_REQUEST 4115 ShouldNotReachHere(); 4116 return; 4117 } 4118 4119 while (true) { 4120 if (sr_notify(osthread) == 0) { 4121 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4122 if (osthread->sr.is_running()) { 4123 return; 4124 } 4125 } 4126 } else { 4127 ShouldNotReachHere(); 4128 } 4129 } 4130 4131 guarantee(osthread->sr.is_running(), "Must be running!"); 4132 } 4133 4134 //////////////////////////////////////////////////////////////////////////////// 4135 // interrupt support 4136 4137 void os::interrupt(Thread* thread) { 4138 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 4139 "possibility of dangling Thread pointer"); 4140 4141 OSThread* osthread = thread->osthread(); 4142 4143 if (!osthread->interrupted()) { 4144 osthread->set_interrupted(true); 4145 // More than one thread can get here with the same value of osthread, 4146 // resulting in multiple notifications. We do, however, want the store 4147 // to interrupted() to be visible to other threads before we execute unpark(). 4148 OrderAccess::fence(); 4149 ParkEvent * const slp = thread->_SleepEvent ; 4150 if (slp != NULL) slp->unpark() ; 4151 } 4152 4153 // For JSR166. Unpark even if interrupt status already was set 4154 if (thread->is_Java_thread()) 4155 ((JavaThread*)thread)->parker()->unpark(); 4156 4157 ParkEvent * ev = thread->_ParkEvent ; 4158 if (ev != NULL) ev->unpark() ; 4159 4160 } 4161 4162 bool os::is_interrupted(Thread* thread, bool clear_interrupted) { 4163 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 4164 "possibility of dangling Thread pointer"); 4165 4166 OSThread* osthread = thread->osthread(); 4167 4168 bool interrupted = osthread->interrupted(); 4169 4170 if (interrupted && clear_interrupted) { 4171 osthread->set_interrupted(false); 4172 // consider thread->_SleepEvent->reset() ... optional optimization 4173 } 4174 4175 return interrupted; 4176 } 4177 4178 /////////////////////////////////////////////////////////////////////////////////// 4179 // signal handling (except suspend/resume) 4180 4181 // This routine may be used by user applications as a "hook" to catch signals. 4182 // The user-defined signal handler must pass unrecognized signals to this 4183 // routine, and if it returns true (non-zero), then the signal handler must 4184 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4185 // routine will never retun false (zero), but instead will execute a VM panic 4186 // routine kill the process. 4187 // 4188 // If this routine returns false, it is OK to call it again. This allows 4189 // the user-defined signal handler to perform checks either before or after 4190 // the VM performs its own checks. Naturally, the user code would be making 4191 // a serious error if it tried to handle an exception (such as a null check 4192 // or breakpoint) that the VM was generating for its own correct operation. 4193 // 4194 // This routine may recognize any of the following kinds of signals: 4195 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4196 // It should be consulted by handlers for any of those signals. 4197 // 4198 // The caller of this routine must pass in the three arguments supplied 4199 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4200 // field of the structure passed to sigaction(). This routine assumes that 4201 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4202 // 4203 // Note that the VM will print warnings if it detects conflicting signal 4204 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4205 // 4206 extern "C" JNIEXPORT int 4207 JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 4208 void* ucontext, int abort_if_unrecognized); 4209 4210 void signalHandler(int sig, siginfo_t* info, void* uc) { 4211 assert(info != NULL && uc != NULL, "it must be old kernel"); 4212 int orig_errno = errno; // Preserve errno value over signal handler. 4213 JVM_handle_linux_signal(sig, info, uc, true); 4214 errno = orig_errno; 4215 } 4216 4217 4218 // This boolean allows users to forward their own non-matching signals 4219 // to JVM_handle_linux_signal, harmlessly. 4220 bool os::Linux::signal_handlers_are_installed = false; 4221 4222 // For signal-chaining 4223 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4224 unsigned int os::Linux::sigs = 0; 4225 bool os::Linux::libjsig_is_loaded = false; 4226 typedef struct sigaction *(*get_signal_t)(int); 4227 get_signal_t os::Linux::get_signal_action = NULL; 4228 4229 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4230 struct sigaction *actp = NULL; 4231 4232 if (libjsig_is_loaded) { 4233 // Retrieve the old signal handler from libjsig 4234 actp = (*get_signal_action)(sig); 4235 } 4236 if (actp == NULL) { 4237 // Retrieve the preinstalled signal handler from jvm 4238 actp = get_preinstalled_handler(sig); 4239 } 4240 4241 return actp; 4242 } 4243 4244 static bool call_chained_handler(struct sigaction *actp, int sig, 4245 siginfo_t *siginfo, void *context) { 4246 // Call the old signal handler 4247 if (actp->sa_handler == SIG_DFL) { 4248 // It's more reasonable to let jvm treat it as an unexpected exception 4249 // instead of taking the default action. 4250 return false; 4251 } else if (actp->sa_handler != SIG_IGN) { 4252 if ((actp->sa_flags & SA_NODEFER) == 0) { 4253 // automaticlly block the signal 4254 sigaddset(&(actp->sa_mask), sig); 4255 } 4256 4257 sa_handler_t hand; 4258 sa_sigaction_t sa; 4259 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4260 // retrieve the chained handler 4261 if (siginfo_flag_set) { 4262 sa = actp->sa_sigaction; 4263 } else { 4264 hand = actp->sa_handler; 4265 } 4266 4267 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4268 actp->sa_handler = SIG_DFL; 4269 } 4270 4271 // try to honor the signal mask 4272 sigset_t oset; 4273 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4274 4275 // call into the chained handler 4276 if (siginfo_flag_set) { 4277 (*sa)(sig, siginfo, context); 4278 } else { 4279 (*hand)(sig); 4280 } 4281 4282 // restore the signal mask 4283 pthread_sigmask(SIG_SETMASK, &oset, 0); 4284 } 4285 // Tell jvm's signal handler the signal is taken care of. 4286 return true; 4287 } 4288 4289 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4290 bool chained = false; 4291 // signal-chaining 4292 if (UseSignalChaining) { 4293 struct sigaction *actp = get_chained_signal_action(sig); 4294 if (actp != NULL) { 4295 chained = call_chained_handler(actp, sig, siginfo, context); 4296 } 4297 } 4298 return chained; 4299 } 4300 4301 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4302 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 4303 return &sigact[sig]; 4304 } 4305 return NULL; 4306 } 4307 4308 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4309 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4310 sigact[sig] = oldAct; 4311 sigs |= (unsigned int)1 << sig; 4312 } 4313 4314 // for diagnostic 4315 int os::Linux::sigflags[MAXSIGNUM]; 4316 4317 int os::Linux::get_our_sigflags(int sig) { 4318 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4319 return sigflags[sig]; 4320 } 4321 4322 void os::Linux::set_our_sigflags(int sig, int flags) { 4323 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4324 sigflags[sig] = flags; 4325 } 4326 4327 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4328 // Check for overwrite. 4329 struct sigaction oldAct; 4330 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4331 4332 void* oldhand = oldAct.sa_sigaction 4333 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4334 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4335 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4336 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4337 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4338 if (AllowUserSignalHandlers || !set_installed) { 4339 // Do not overwrite; user takes responsibility to forward to us. 4340 return; 4341 } else if (UseSignalChaining) { 4342 // save the old handler in jvm 4343 save_preinstalled_handler(sig, oldAct); 4344 // libjsig also interposes the sigaction() call below and saves the 4345 // old sigaction on it own. 4346 } else { 4347 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4348 "%#lx for signal %d.", (long)oldhand, sig)); 4349 } 4350 } 4351 4352 struct sigaction sigAct; 4353 sigfillset(&(sigAct.sa_mask)); 4354 sigAct.sa_handler = SIG_DFL; 4355 if (!set_installed) { 4356 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4357 } else { 4358 sigAct.sa_sigaction = signalHandler; 4359 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4360 } 4361 // Save flags, which are set by ours 4362 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4363 sigflags[sig] = sigAct.sa_flags; 4364 4365 int ret = sigaction(sig, &sigAct, &oldAct); 4366 assert(ret == 0, "check"); 4367 4368 void* oldhand2 = oldAct.sa_sigaction 4369 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4370 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4371 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4372 } 4373 4374 // install signal handlers for signals that HotSpot needs to 4375 // handle in order to support Java-level exception handling. 4376 4377 void os::Linux::install_signal_handlers() { 4378 if (!signal_handlers_are_installed) { 4379 signal_handlers_are_installed = true; 4380 4381 // signal-chaining 4382 typedef void (*signal_setting_t)(); 4383 signal_setting_t begin_signal_setting = NULL; 4384 signal_setting_t end_signal_setting = NULL; 4385 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4386 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4387 if (begin_signal_setting != NULL) { 4388 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4389 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4390 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4391 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4392 libjsig_is_loaded = true; 4393 assert(UseSignalChaining, "should enable signal-chaining"); 4394 } 4395 if (libjsig_is_loaded) { 4396 // Tell libjsig jvm is setting signal handlers 4397 (*begin_signal_setting)(); 4398 } 4399 4400 set_signal_handler(SIGSEGV, true); 4401 set_signal_handler(SIGPIPE, true); 4402 set_signal_handler(SIGBUS, true); 4403 set_signal_handler(SIGILL, true); 4404 set_signal_handler(SIGFPE, true); 4405 set_signal_handler(SIGXFSZ, true); 4406 4407 if (libjsig_is_loaded) { 4408 // Tell libjsig jvm finishes setting signal handlers 4409 (*end_signal_setting)(); 4410 } 4411 4412 // We don't activate signal checker if libjsig is in place, we trust ourselves 4413 // and if UserSignalHandler is installed all bets are off. 4414 // Log that signal checking is off only if -verbose:jni is specified. 4415 if (CheckJNICalls) { 4416 if (libjsig_is_loaded) { 4417 if (PrintJNIResolving) { 4418 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4419 } 4420 check_signals = false; 4421 } 4422 if (AllowUserSignalHandlers) { 4423 if (PrintJNIResolving) { 4424 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4425 } 4426 check_signals = false; 4427 } 4428 } 4429 } 4430 } 4431 4432 // This is the fastest way to get thread cpu time on Linux. 4433 // Returns cpu time (user+sys) for any thread, not only for current. 4434 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4435 // It might work on 2.6.10+ with a special kernel/glibc patch. 4436 // For reference, please, see IEEE Std 1003.1-2004: 4437 // http://www.unix.org/single_unix_specification 4438 4439 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4440 struct timespec tp; 4441 int rc = os::Linux::clock_gettime(clockid, &tp); 4442 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4443 4444 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4445 } 4446 4447 ///// 4448 // glibc on Linux platform uses non-documented flag 4449 // to indicate, that some special sort of signal 4450 // trampoline is used. 4451 // We will never set this flag, and we should 4452 // ignore this flag in our diagnostic 4453 #ifdef SIGNIFICANT_SIGNAL_MASK 4454 #undef SIGNIFICANT_SIGNAL_MASK 4455 #endif 4456 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4457 4458 static const char* get_signal_handler_name(address handler, 4459 char* buf, int buflen) { 4460 int offset; 4461 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4462 if (found) { 4463 // skip directory names 4464 const char *p1, *p2; 4465 p1 = buf; 4466 size_t len = strlen(os::file_separator()); 4467 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4468 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4469 } else { 4470 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4471 } 4472 return buf; 4473 } 4474 4475 static void print_signal_handler(outputStream* st, int sig, 4476 char* buf, size_t buflen) { 4477 struct sigaction sa; 4478 4479 sigaction(sig, NULL, &sa); 4480 4481 // See comment for SIGNIFICANT_SIGNAL_MASK define 4482 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4483 4484 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4485 4486 address handler = (sa.sa_flags & SA_SIGINFO) 4487 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4488 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4489 4490 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4491 st->print("SIG_DFL"); 4492 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4493 st->print("SIG_IGN"); 4494 } else { 4495 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4496 } 4497 4498 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask); 4499 4500 address rh = VMError::get_resetted_sighandler(sig); 4501 // May be, handler was resetted by VMError? 4502 if(rh != NULL) { 4503 handler = rh; 4504 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4505 } 4506 4507 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags); 4508 4509 // Check: is it our handler? 4510 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4511 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4512 // It is our signal handler 4513 // check for flags, reset system-used one! 4514 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4515 st->print( 4516 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4517 os::Linux::get_our_sigflags(sig)); 4518 } 4519 } 4520 st->cr(); 4521 } 4522 4523 4524 #define DO_SIGNAL_CHECK(sig) \ 4525 if (!sigismember(&check_signal_done, sig)) \ 4526 os::Linux::check_signal_handler(sig) 4527 4528 // This method is a periodic task to check for misbehaving JNI applications 4529 // under CheckJNI, we can add any periodic checks here 4530 4531 void os::run_periodic_checks() { 4532 4533 if (check_signals == false) return; 4534 4535 // SEGV and BUS if overridden could potentially prevent 4536 // generation of hs*.log in the event of a crash, debugging 4537 // such a case can be very challenging, so we absolutely 4538 // check the following for a good measure: 4539 DO_SIGNAL_CHECK(SIGSEGV); 4540 DO_SIGNAL_CHECK(SIGILL); 4541 DO_SIGNAL_CHECK(SIGFPE); 4542 DO_SIGNAL_CHECK(SIGBUS); 4543 DO_SIGNAL_CHECK(SIGPIPE); 4544 DO_SIGNAL_CHECK(SIGXFSZ); 4545 4546 4547 // ReduceSignalUsage allows the user to override these handlers 4548 // see comments at the very top and jvm_solaris.h 4549 if (!ReduceSignalUsage) { 4550 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4551 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4552 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4553 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4554 } 4555 4556 DO_SIGNAL_CHECK(SR_signum); 4557 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4558 } 4559 4560 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4561 4562 static os_sigaction_t os_sigaction = NULL; 4563 4564 void os::Linux::check_signal_handler(int sig) { 4565 char buf[O_BUFLEN]; 4566 address jvmHandler = NULL; 4567 4568 4569 struct sigaction act; 4570 if (os_sigaction == NULL) { 4571 // only trust the default sigaction, in case it has been interposed 4572 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4573 if (os_sigaction == NULL) return; 4574 } 4575 4576 os_sigaction(sig, (struct sigaction*)NULL, &act); 4577 4578 4579 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4580 4581 address thisHandler = (act.sa_flags & SA_SIGINFO) 4582 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4583 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 4584 4585 4586 switch(sig) { 4587 case SIGSEGV: 4588 case SIGBUS: 4589 case SIGFPE: 4590 case SIGPIPE: 4591 case SIGILL: 4592 case SIGXFSZ: 4593 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4594 break; 4595 4596 case SHUTDOWN1_SIGNAL: 4597 case SHUTDOWN2_SIGNAL: 4598 case SHUTDOWN3_SIGNAL: 4599 case BREAK_SIGNAL: 4600 jvmHandler = (address)user_handler(); 4601 break; 4602 4603 case INTERRUPT_SIGNAL: 4604 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4605 break; 4606 4607 default: 4608 if (sig == SR_signum) { 4609 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4610 } else { 4611 return; 4612 } 4613 break; 4614 } 4615 4616 if (thisHandler != jvmHandler) { 4617 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4618 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4619 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4620 // No need to check this sig any longer 4621 sigaddset(&check_signal_done, sig); 4622 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4623 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4624 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4625 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4626 // No need to check this sig any longer 4627 sigaddset(&check_signal_done, sig); 4628 } 4629 4630 // Dump all the signal 4631 if (sigismember(&check_signal_done, sig)) { 4632 print_signal_handlers(tty, buf, O_BUFLEN); 4633 } 4634 } 4635 4636 extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 4637 4638 extern bool signal_name(int signo, char* buf, size_t len); 4639 4640 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4641 if (0 < exception_code && exception_code <= SIGRTMAX) { 4642 // signal 4643 if (!signal_name(exception_code, buf, size)) { 4644 jio_snprintf(buf, size, "SIG%d", exception_code); 4645 } 4646 return buf; 4647 } else { 4648 return NULL; 4649 } 4650 } 4651 4652 // this is called _before_ the most of global arguments have been parsed 4653 void os::init(void) { 4654 char dummy; /* used to get a guess on initial stack address */ 4655 // first_hrtime = gethrtime(); 4656 4657 // With LinuxThreads the JavaMain thread pid (primordial thread) 4658 // is different than the pid of the java launcher thread. 4659 // So, on Linux, the launcher thread pid is passed to the VM 4660 // via the sun.java.launcher.pid property. 4661 // Use this property instead of getpid() if it was correctly passed. 4662 // See bug 6351349. 4663 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4664 4665 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4666 4667 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4668 4669 init_random(1234567); 4670 4671 ThreadCritical::initialize(); 4672 4673 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4674 if (Linux::page_size() == -1) { 4675 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4676 strerror(errno))); 4677 } 4678 init_page_sizes((size_t) Linux::page_size()); 4679 4680 Linux::initialize_system_info(); 4681 4682 // main_thread points to the aboriginal thread 4683 Linux::_main_thread = pthread_self(); 4684 4685 Linux::clock_init(); 4686 initial_time_count = os::elapsed_counter(); 4687 pthread_mutex_init(&dl_mutex, NULL); 4688 4689 // If the pagesize of the VM is greater than 8K determine the appropriate 4690 // number of initial guard pages. The user can change this with the 4691 // command line arguments, if needed. 4692 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4693 StackYellowPages = 1; 4694 StackRedPages = 1; 4695 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4696 } 4697 } 4698 4699 // To install functions for atexit system call 4700 extern "C" { 4701 static void perfMemory_exit_helper() { 4702 perfMemory_exit(); 4703 } 4704 } 4705 4706 // this is called _after_ the global arguments have been parsed 4707 jint os::init_2(void) 4708 { 4709 Linux::fast_thread_clock_init(); 4710 4711 // Allocate a single page and mark it as readable for safepoint polling 4712 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4713 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 4714 4715 os::set_polling_page( polling_page ); 4716 4717 #ifndef PRODUCT 4718 if(Verbose && PrintMiscellaneous) 4719 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 4720 #endif 4721 4722 if (!UseMembar) { 4723 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4724 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4725 os::set_memory_serialize_page( mem_serialize_page ); 4726 4727 #ifndef PRODUCT 4728 if(Verbose && PrintMiscellaneous) 4729 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 4730 #endif 4731 } 4732 4733 // initialize suspend/resume support - must do this before signal_sets_init() 4734 if (SR_initialize() != 0) { 4735 perror("SR_initialize failed"); 4736 return JNI_ERR; 4737 } 4738 4739 Linux::signal_sets_init(); 4740 Linux::install_signal_handlers(); 4741 4742 // Check minimum allowable stack size for thread creation and to initialize 4743 // the java system classes, including StackOverflowError - depends on page 4744 // size. Add a page for compiler2 recursion in main thread. 4745 // Add in 2*BytesPerWord times page size to account for VM stack during 4746 // class initialization depending on 32 or 64 bit VM. 4747 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4748 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4749 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4750 4751 size_t threadStackSizeInBytes = ThreadStackSize * K; 4752 if (threadStackSizeInBytes != 0 && 4753 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4754 tty->print_cr("\nThe stack size specified is too small, " 4755 "Specify at least %dk", 4756 os::Linux::min_stack_allowed/ K); 4757 return JNI_ERR; 4758 } 4759 4760 // Make the stack size a multiple of the page size so that 4761 // the yellow/red zones can be guarded. 4762 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4763 vm_page_size())); 4764 4765 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4766 4767 Linux::libpthread_init(); 4768 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4769 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4770 Linux::glibc_version(), Linux::libpthread_version(), 4771 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4772 } 4773 4774 if (UseNUMA) { 4775 if (!Linux::libnuma_init()) { 4776 UseNUMA = false; 4777 } else { 4778 if ((Linux::numa_max_node() < 1)) { 4779 // There's only one node(they start from 0), disable NUMA. 4780 UseNUMA = false; 4781 } 4782 } 4783 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4784 // we can make the adaptive lgrp chunk resizing work. If the user specified 4785 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4786 // disable adaptive resizing. 4787 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4788 if (FLAG_IS_DEFAULT(UseNUMA)) { 4789 UseNUMA = false; 4790 } else { 4791 if (FLAG_IS_DEFAULT(UseLargePages) && 4792 FLAG_IS_DEFAULT(UseSHM) && 4793 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4794 UseLargePages = false; 4795 } else { 4796 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4797 UseAdaptiveSizePolicy = false; 4798 UseAdaptiveNUMAChunkSizing = false; 4799 } 4800 } 4801 } 4802 if (!UseNUMA && ForceNUMA) { 4803 UseNUMA = true; 4804 } 4805 } 4806 4807 if (MaxFDLimit) { 4808 // set the number of file descriptors to max. print out error 4809 // if getrlimit/setrlimit fails but continue regardless. 4810 struct rlimit nbr_files; 4811 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4812 if (status != 0) { 4813 if (PrintMiscellaneous && (Verbose || WizardMode)) 4814 perror("os::init_2 getrlimit failed"); 4815 } else { 4816 nbr_files.rlim_cur = nbr_files.rlim_max; 4817 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4818 if (status != 0) { 4819 if (PrintMiscellaneous && (Verbose || WizardMode)) 4820 perror("os::init_2 setrlimit failed"); 4821 } 4822 } 4823 } 4824 4825 // Initialize lock used to serialize thread creation (see os::create_thread) 4826 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4827 4828 // at-exit methods are called in the reverse order of their registration. 4829 // atexit functions are called on return from main or as a result of a 4830 // call to exit(3C). There can be only 32 of these functions registered 4831 // and atexit() does not set errno. 4832 4833 if (PerfAllowAtExitRegistration) { 4834 // only register atexit functions if PerfAllowAtExitRegistration is set. 4835 // atexit functions can be delayed until process exit time, which 4836 // can be problematic for embedded VM situations. Embedded VMs should 4837 // call DestroyJavaVM() to assure that VM resources are released. 4838 4839 // note: perfMemory_exit_helper atexit function may be removed in 4840 // the future if the appropriate cleanup code can be added to the 4841 // VM_Exit VMOperation's doit method. 4842 if (atexit(perfMemory_exit_helper) != 0) { 4843 warning("os::init2 atexit(perfMemory_exit_helper) failed"); 4844 } 4845 } 4846 4847 // initialize thread priority policy 4848 prio_init(); 4849 4850 return JNI_OK; 4851 } 4852 4853 // this is called at the end of vm_initialization 4854 void os::init_3(void) 4855 { 4856 #ifdef JAVASE_EMBEDDED 4857 // Start the MemNotifyThread 4858 if (LowMemoryProtection) { 4859 MemNotifyThread::start(); 4860 } 4861 return; 4862 #endif 4863 } 4864 4865 // Mark the polling page as unreadable 4866 void os::make_polling_page_unreadable(void) { 4867 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 4868 fatal("Could not disable polling page"); 4869 }; 4870 4871 // Mark the polling page as readable 4872 void os::make_polling_page_readable(void) { 4873 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4874 fatal("Could not enable polling page"); 4875 } 4876 }; 4877 4878 int os::active_processor_count() { 4879 // Linux doesn't yet have a (official) notion of processor sets, 4880 // so just return the number of online processors. 4881 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4882 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4883 return online_cpus; 4884 } 4885 4886 void os::set_native_thread_name(const char *name) { 4887 // Not yet implemented. 4888 return; 4889 } 4890 4891 bool os::distribute_processes(uint length, uint* distribution) { 4892 // Not yet implemented. 4893 return false; 4894 } 4895 4896 bool os::bind_to_processor(uint processor_id) { 4897 // Not yet implemented. 4898 return false; 4899 } 4900 4901 /// 4902 4903 void os::SuspendedThreadTask::internal_do_task() { 4904 if (do_suspend(_thread->osthread())) { 4905 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4906 do_task(context); 4907 do_resume(_thread->osthread()); 4908 } 4909 } 4910 4911 class PcFetcher : public os::SuspendedThreadTask { 4912 public: 4913 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4914 ExtendedPC result(); 4915 protected: 4916 void do_task(const os::SuspendedThreadTaskContext& context); 4917 private: 4918 ExtendedPC _epc; 4919 }; 4920 4921 ExtendedPC PcFetcher::result() { 4922 guarantee(is_done(), "task is not done yet."); 4923 return _epc; 4924 } 4925 4926 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 4927 Thread* thread = context.thread(); 4928 OSThread* osthread = thread->osthread(); 4929 if (osthread->ucontext() != NULL) { 4930 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 4931 } else { 4932 // NULL context is unexpected, double-check this is the VMThread 4933 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4934 } 4935 } 4936 4937 // Suspends the target using the signal mechanism and then grabs the PC before 4938 // resuming the target. Used by the flat-profiler only 4939 ExtendedPC os::get_thread_pc(Thread* thread) { 4940 // Make sure that it is called by the watcher for the VMThread 4941 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4942 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4943 4944 PcFetcher fetcher(thread); 4945 fetcher.run(); 4946 return fetcher.result(); 4947 } 4948 4949 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 4950 { 4951 if (is_NPTL()) { 4952 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4953 } else { 4954 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4955 // word back to default 64bit precision if condvar is signaled. Java 4956 // wants 53bit precision. Save and restore current value. 4957 int fpu = get_fpu_control_word(); 4958 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4959 set_fpu_control_word(fpu); 4960 return status; 4961 } 4962 } 4963 4964 //////////////////////////////////////////////////////////////////////////////// 4965 // debug support 4966 4967 bool os::find(address addr, outputStream* st) { 4968 Dl_info dlinfo; 4969 memset(&dlinfo, 0, sizeof(dlinfo)); 4970 if (dladdr(addr, &dlinfo) != 0) { 4971 st->print(PTR_FORMAT ": ", addr); 4972 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 4973 st->print("%s+%#x", dlinfo.dli_sname, 4974 addr - (intptr_t)dlinfo.dli_saddr); 4975 } else if (dlinfo.dli_fbase != NULL) { 4976 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4977 } else { 4978 st->print("<absolute address>"); 4979 } 4980 if (dlinfo.dli_fname != NULL) { 4981 st->print(" in %s", dlinfo.dli_fname); 4982 } 4983 if (dlinfo.dli_fbase != NULL) { 4984 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4985 } 4986 st->cr(); 4987 4988 if (Verbose) { 4989 // decode some bytes around the PC 4990 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 4991 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 4992 address lowest = (address) dlinfo.dli_sname; 4993 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4994 if (begin < lowest) begin = lowest; 4995 Dl_info dlinfo2; 4996 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 4997 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 4998 end = (address) dlinfo2.dli_saddr; 4999 Disassembler::decode(begin, end, st); 5000 } 5001 return true; 5002 } 5003 return false; 5004 } 5005 5006 //////////////////////////////////////////////////////////////////////////////// 5007 // misc 5008 5009 // This does not do anything on Linux. This is basically a hook for being 5010 // able to use structured exception handling (thread-local exception filters) 5011 // on, e.g., Win32. 5012 void 5013 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 5014 JavaCallArguments* args, Thread* thread) { 5015 f(value, method, args, thread); 5016 } 5017 5018 void os::print_statistics() { 5019 } 5020 5021 int os::message_box(const char* title, const char* message) { 5022 int i; 5023 fdStream err(defaultStream::error_fd()); 5024 for (i = 0; i < 78; i++) err.print_raw("="); 5025 err.cr(); 5026 err.print_raw_cr(title); 5027 for (i = 0; i < 78; i++) err.print_raw("-"); 5028 err.cr(); 5029 err.print_raw_cr(message); 5030 for (i = 0; i < 78; i++) err.print_raw("="); 5031 err.cr(); 5032 5033 char buf[16]; 5034 // Prevent process from exiting upon "read error" without consuming all CPU 5035 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 5036 5037 return buf[0] == 'y' || buf[0] == 'Y'; 5038 } 5039 5040 int os::stat(const char *path, struct stat *sbuf) { 5041 char pathbuf[MAX_PATH]; 5042 if (strlen(path) > MAX_PATH - 1) { 5043 errno = ENAMETOOLONG; 5044 return -1; 5045 } 5046 os::native_path(strcpy(pathbuf, path)); 5047 return ::stat(pathbuf, sbuf); 5048 } 5049 5050 bool os::check_heap(bool force) { 5051 return true; 5052 } 5053 5054 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 5055 return ::vsnprintf(buf, count, format, args); 5056 } 5057 5058 // Is a (classpath) directory empty? 5059 bool os::dir_is_empty(const char* path) { 5060 DIR *dir = NULL; 5061 struct dirent *ptr; 5062 5063 dir = opendir(path); 5064 if (dir == NULL) return true; 5065 5066 /* Scan the directory */ 5067 bool result = true; 5068 char buf[sizeof(struct dirent) + MAX_PATH]; 5069 while (result && (ptr = ::readdir(dir)) != NULL) { 5070 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5071 result = false; 5072 } 5073 } 5074 closedir(dir); 5075 return result; 5076 } 5077 5078 // This code originates from JDK's sysOpen and open64_w 5079 // from src/solaris/hpi/src/system_md.c 5080 5081 #ifndef O_DELETE 5082 #define O_DELETE 0x10000 5083 #endif 5084 5085 // Open a file. Unlink the file immediately after open returns 5086 // if the specified oflag has the O_DELETE flag set. 5087 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c 5088 5089 int os::open(const char *path, int oflag, int mode) { 5090 5091 if (strlen(path) > MAX_PATH - 1) { 5092 errno = ENAMETOOLONG; 5093 return -1; 5094 } 5095 int fd; 5096 int o_delete = (oflag & O_DELETE); 5097 oflag = oflag & ~O_DELETE; 5098 5099 fd = ::open64(path, oflag, mode); 5100 if (fd == -1) return -1; 5101 5102 //If the open succeeded, the file might still be a directory 5103 { 5104 struct stat64 buf64; 5105 int ret = ::fstat64(fd, &buf64); 5106 int st_mode = buf64.st_mode; 5107 5108 if (ret != -1) { 5109 if ((st_mode & S_IFMT) == S_IFDIR) { 5110 errno = EISDIR; 5111 ::close(fd); 5112 return -1; 5113 } 5114 } else { 5115 ::close(fd); 5116 return -1; 5117 } 5118 } 5119 5120 /* 5121 * All file descriptors that are opened in the JVM and not 5122 * specifically destined for a subprocess should have the 5123 * close-on-exec flag set. If we don't set it, then careless 3rd 5124 * party native code might fork and exec without closing all 5125 * appropriate file descriptors (e.g. as we do in closeDescriptors in 5126 * UNIXProcess.c), and this in turn might: 5127 * 5128 * - cause end-of-file to fail to be detected on some file 5129 * descriptors, resulting in mysterious hangs, or 5130 * 5131 * - might cause an fopen in the subprocess to fail on a system 5132 * suffering from bug 1085341. 5133 * 5134 * (Yes, the default setting of the close-on-exec flag is a Unix 5135 * design flaw) 5136 * 5137 * See: 5138 * 1085341: 32-bit stdio routines should support file descriptors >255 5139 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5140 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5141 */ 5142 #ifdef FD_CLOEXEC 5143 { 5144 int flags = ::fcntl(fd, F_GETFD); 5145 if (flags != -1) 5146 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5147 } 5148 #endif 5149 5150 if (o_delete != 0) { 5151 ::unlink(path); 5152 } 5153 return fd; 5154 } 5155 5156 5157 // create binary file, rewriting existing file if required 5158 int os::create_binary_file(const char* path, bool rewrite_existing) { 5159 int oflags = O_WRONLY | O_CREAT; 5160 if (!rewrite_existing) { 5161 oflags |= O_EXCL; 5162 } 5163 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5164 } 5165 5166 // return current position of file pointer 5167 jlong os::current_file_offset(int fd) { 5168 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5169 } 5170 5171 // move file pointer to the specified offset 5172 jlong os::seek_to_file_offset(int fd, jlong offset) { 5173 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5174 } 5175 5176 // This code originates from JDK's sysAvailable 5177 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5178 5179 int os::available(int fd, jlong *bytes) { 5180 jlong cur, end; 5181 int mode; 5182 struct stat64 buf64; 5183 5184 if (::fstat64(fd, &buf64) >= 0) { 5185 mode = buf64.st_mode; 5186 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5187 /* 5188 * XXX: is the following call interruptible? If so, this might 5189 * need to go through the INTERRUPT_IO() wrapper as for other 5190 * blocking, interruptible calls in this file. 5191 */ 5192 int n; 5193 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5194 *bytes = n; 5195 return 1; 5196 } 5197 } 5198 } 5199 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5200 return 0; 5201 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5202 return 0; 5203 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5204 return 0; 5205 } 5206 *bytes = end - cur; 5207 return 1; 5208 } 5209 5210 int os::socket_available(int fd, jint *pbytes) { 5211 // Linux doc says EINTR not returned, unlike Solaris 5212 int ret = ::ioctl(fd, FIONREAD, pbytes); 5213 5214 //%% note ioctl can return 0 when successful, JVM_SocketAvailable 5215 // is expected to return 0 on failure and 1 on success to the jdk. 5216 return (ret < 0) ? 0 : 1; 5217 } 5218 5219 // Map a block of memory. 5220 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5221 char *addr, size_t bytes, bool read_only, 5222 bool allow_exec) { 5223 int prot; 5224 int flags = MAP_PRIVATE; 5225 5226 if (read_only) { 5227 prot = PROT_READ; 5228 } else { 5229 prot = PROT_READ | PROT_WRITE; 5230 } 5231 5232 if (allow_exec) { 5233 prot |= PROT_EXEC; 5234 } 5235 5236 if (addr != NULL) { 5237 flags |= MAP_FIXED; 5238 } 5239 5240 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5241 fd, file_offset); 5242 if (mapped_address == MAP_FAILED) { 5243 return NULL; 5244 } 5245 return mapped_address; 5246 } 5247 5248 5249 // Remap a block of memory. 5250 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5251 char *addr, size_t bytes, bool read_only, 5252 bool allow_exec) { 5253 // same as map_memory() on this OS 5254 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5255 allow_exec); 5256 } 5257 5258 5259 // Unmap a block of memory. 5260 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5261 return munmap(addr, bytes) == 0; 5262 } 5263 5264 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5265 5266 static clockid_t thread_cpu_clockid(Thread* thread) { 5267 pthread_t tid = thread->osthread()->pthread_id(); 5268 clockid_t clockid; 5269 5270 // Get thread clockid 5271 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5272 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5273 return clockid; 5274 } 5275 5276 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5277 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5278 // of a thread. 5279 // 5280 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5281 // the fast estimate available on the platform. 5282 5283 jlong os::current_thread_cpu_time() { 5284 if (os::Linux::supports_fast_thread_cpu_time()) { 5285 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5286 } else { 5287 // return user + sys since the cost is the same 5288 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5289 } 5290 } 5291 5292 jlong os::thread_cpu_time(Thread* thread) { 5293 // consistent with what current_thread_cpu_time() returns 5294 if (os::Linux::supports_fast_thread_cpu_time()) { 5295 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5296 } else { 5297 return slow_thread_cpu_time(thread, true /* user + sys */); 5298 } 5299 } 5300 5301 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5302 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5303 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5304 } else { 5305 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5306 } 5307 } 5308 5309 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5310 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5311 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5312 } else { 5313 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5314 } 5315 } 5316 5317 // 5318 // -1 on error. 5319 // 5320 5321 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5322 static bool proc_task_unchecked = true; 5323 static const char *proc_stat_path = "/proc/%d/stat"; 5324 pid_t tid = thread->osthread()->thread_id(); 5325 char *s; 5326 char stat[2048]; 5327 int statlen; 5328 char proc_name[64]; 5329 int count; 5330 long sys_time, user_time; 5331 char cdummy; 5332 int idummy; 5333 long ldummy; 5334 FILE *fp; 5335 5336 // The /proc/<tid>/stat aggregates per-process usage on 5337 // new Linux kernels 2.6+ where NPTL is supported. 5338 // The /proc/self/task/<tid>/stat still has the per-thread usage. 5339 // See bug 6328462. 5340 // There possibly can be cases where there is no directory 5341 // /proc/self/task, so we check its availability. 5342 if (proc_task_unchecked && os::Linux::is_NPTL()) { 5343 // This is executed only once 5344 proc_task_unchecked = false; 5345 fp = fopen("/proc/self/task", "r"); 5346 if (fp != NULL) { 5347 proc_stat_path = "/proc/self/task/%d/stat"; 5348 fclose(fp); 5349 } 5350 } 5351 5352 sprintf(proc_name, proc_stat_path, tid); 5353 fp = fopen(proc_name, "r"); 5354 if ( fp == NULL ) return -1; 5355 statlen = fread(stat, 1, 2047, fp); 5356 stat[statlen] = '\0'; 5357 fclose(fp); 5358 5359 // Skip pid and the command string. Note that we could be dealing with 5360 // weird command names, e.g. user could decide to rename java launcher 5361 // to "java 1.4.2 :)", then the stat file would look like 5362 // 1234 (java 1.4.2 :)) R ... ... 5363 // We don't really need to know the command string, just find the last 5364 // occurrence of ")" and then start parsing from there. See bug 4726580. 5365 s = strrchr(stat, ')'); 5366 if (s == NULL ) return -1; 5367 5368 // Skip blank chars 5369 do s++; while (isspace(*s)); 5370 5371 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5372 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5373 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5374 &user_time, &sys_time); 5375 if ( count != 13 ) return -1; 5376 if (user_sys_cpu_time) { 5377 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5378 } else { 5379 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5380 } 5381 } 5382 5383 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5384 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5385 info_ptr->may_skip_backward = false; // elapsed time not wall time 5386 info_ptr->may_skip_forward = false; // elapsed time not wall time 5387 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5388 } 5389 5390 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5391 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5392 info_ptr->may_skip_backward = false; // elapsed time not wall time 5393 info_ptr->may_skip_forward = false; // elapsed time not wall time 5394 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5395 } 5396 5397 bool os::is_thread_cpu_time_supported() { 5398 return true; 5399 } 5400 5401 // System loadavg support. Returns -1 if load average cannot be obtained. 5402 // Linux doesn't yet have a (official) notion of processor sets, 5403 // so just return the system wide load average. 5404 int os::loadavg(double loadavg[], int nelem) { 5405 return ::getloadavg(loadavg, nelem); 5406 } 5407 5408 void os::pause() { 5409 char filename[MAX_PATH]; 5410 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5411 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5412 } else { 5413 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5414 } 5415 5416 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5417 if (fd != -1) { 5418 struct stat buf; 5419 ::close(fd); 5420 while (::stat(filename, &buf) == 0) { 5421 (void)::poll(NULL, 0, 100); 5422 } 5423 } else { 5424 jio_fprintf(stderr, 5425 "Could not open pause file '%s', continuing immediately.\n", filename); 5426 } 5427 } 5428 5429 5430 // Refer to the comments in os_solaris.cpp park-unpark. 5431 // 5432 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5433 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5434 // For specifics regarding the bug see GLIBC BUGID 261237 : 5435 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5436 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5437 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5438 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5439 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5440 // and monitorenter when we're using 1-0 locking. All those operations may result in 5441 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5442 // of libpthread avoids the problem, but isn't practical. 5443 // 5444 // Possible remedies: 5445 // 5446 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5447 // This is palliative and probabilistic, however. If the thread is preempted 5448 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5449 // than the minimum period may have passed, and the abstime may be stale (in the 5450 // past) resultin in a hang. Using this technique reduces the odds of a hang 5451 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5452 // 5453 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5454 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5455 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5456 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5457 // thread. 5458 // 5459 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5460 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5461 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5462 // This also works well. In fact it avoids kernel-level scalability impediments 5463 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5464 // timers in a graceful fashion. 5465 // 5466 // 4. When the abstime value is in the past it appears that control returns 5467 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5468 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5469 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5470 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5471 // It may be possible to avoid reinitialization by checking the return 5472 // value from pthread_cond_timedwait(). In addition to reinitializing the 5473 // condvar we must establish the invariant that cond_signal() is only called 5474 // within critical sections protected by the adjunct mutex. This prevents 5475 // cond_signal() from "seeing" a condvar that's in the midst of being 5476 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5477 // desirable signal-after-unlock optimization that avoids futile context switching. 5478 // 5479 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5480 // structure when a condvar is used or initialized. cond_destroy() would 5481 // release the helper structure. Our reinitialize-after-timedwait fix 5482 // put excessive stress on malloc/free and locks protecting the c-heap. 5483 // 5484 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5485 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5486 // and only enabling the work-around for vulnerable environments. 5487 5488 // utility to compute the abstime argument to timedwait: 5489 // millis is the relative timeout time 5490 // abstime will be the absolute timeout time 5491 // TODO: replace compute_abstime() with unpackTime() 5492 5493 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5494 if (millis < 0) millis = 0; 5495 struct timeval now; 5496 int status = gettimeofday(&now, NULL); 5497 assert(status == 0, "gettimeofday"); 5498 jlong seconds = millis / 1000; 5499 millis %= 1000; 5500 if (seconds > 50000000) { // see man cond_timedwait(3T) 5501 seconds = 50000000; 5502 } 5503 abstime->tv_sec = now.tv_sec + seconds; 5504 long usec = now.tv_usec + millis * 1000; 5505 if (usec >= 1000000) { 5506 abstime->tv_sec += 1; 5507 usec -= 1000000; 5508 } 5509 abstime->tv_nsec = usec * 1000; 5510 return abstime; 5511 } 5512 5513 5514 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 5515 // Conceptually TryPark() should be equivalent to park(0). 5516 5517 int os::PlatformEvent::TryPark() { 5518 for (;;) { 5519 const int v = _Event ; 5520 guarantee ((v == 0) || (v == 1), "invariant") ; 5521 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 5522 } 5523 } 5524 5525 void os::PlatformEvent::park() { // AKA "down()" 5526 // Invariant: Only the thread associated with the Event/PlatformEvent 5527 // may call park(). 5528 // TODO: assert that _Assoc != NULL or _Assoc == Self 5529 int v ; 5530 for (;;) { 5531 v = _Event ; 5532 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5533 } 5534 guarantee (v >= 0, "invariant") ; 5535 if (v == 0) { 5536 // Do this the hard way by blocking ... 5537 int status = pthread_mutex_lock(_mutex); 5538 assert_status(status == 0, status, "mutex_lock"); 5539 guarantee (_nParked == 0, "invariant") ; 5540 ++ _nParked ; 5541 while (_Event < 0) { 5542 status = pthread_cond_wait(_cond, _mutex); 5543 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5544 // Treat this the same as if the wait was interrupted 5545 if (status == ETIME) { status = EINTR; } 5546 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5547 } 5548 -- _nParked ; 5549 5550 _Event = 0 ; 5551 status = pthread_mutex_unlock(_mutex); 5552 assert_status(status == 0, status, "mutex_unlock"); 5553 // Paranoia to ensure our locked and lock-free paths interact 5554 // correctly with each other. 5555 OrderAccess::fence(); 5556 } 5557 guarantee (_Event >= 0, "invariant") ; 5558 } 5559 5560 int os::PlatformEvent::park(jlong millis) { 5561 guarantee (_nParked == 0, "invariant") ; 5562 5563 int v ; 5564 for (;;) { 5565 v = _Event ; 5566 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5567 } 5568 guarantee (v >= 0, "invariant") ; 5569 if (v != 0) return OS_OK ; 5570 5571 // We do this the hard way, by blocking the thread. 5572 // Consider enforcing a minimum timeout value. 5573 struct timespec abst; 5574 compute_abstime(&abst, millis); 5575 5576 int ret = OS_TIMEOUT; 5577 int status = pthread_mutex_lock(_mutex); 5578 assert_status(status == 0, status, "mutex_lock"); 5579 guarantee (_nParked == 0, "invariant") ; 5580 ++_nParked ; 5581 5582 // Object.wait(timo) will return because of 5583 // (a) notification 5584 // (b) timeout 5585 // (c) thread.interrupt 5586 // 5587 // Thread.interrupt and object.notify{All} both call Event::set. 5588 // That is, we treat thread.interrupt as a special case of notification. 5589 // The underlying Solaris implementation, cond_timedwait, admits 5590 // spurious/premature wakeups, but the JLS/JVM spec prevents the 5591 // JVM from making those visible to Java code. As such, we must 5592 // filter out spurious wakeups. We assume all ETIME returns are valid. 5593 // 5594 // TODO: properly differentiate simultaneous notify+interrupt. 5595 // In that case, we should propagate the notify to another waiter. 5596 5597 while (_Event < 0) { 5598 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5599 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5600 pthread_cond_destroy (_cond); 5601 pthread_cond_init (_cond, NULL) ; 5602 } 5603 assert_status(status == 0 || status == EINTR || 5604 status == ETIME || status == ETIMEDOUT, 5605 status, "cond_timedwait"); 5606 if (!FilterSpuriousWakeups) break ; // previous semantics 5607 if (status == ETIME || status == ETIMEDOUT) break ; 5608 // We consume and ignore EINTR and spurious wakeups. 5609 } 5610 --_nParked ; 5611 if (_Event >= 0) { 5612 ret = OS_OK; 5613 } 5614 _Event = 0 ; 5615 status = pthread_mutex_unlock(_mutex); 5616 assert_status(status == 0, status, "mutex_unlock"); 5617 assert (_nParked == 0, "invariant") ; 5618 // Paranoia to ensure our locked and lock-free paths interact 5619 // correctly with each other. 5620 OrderAccess::fence(); 5621 return ret; 5622 } 5623 5624 void os::PlatformEvent::unpark() { 5625 // Transitions for _Event: 5626 // 0 :=> 1 5627 // 1 :=> 1 5628 // -1 :=> either 0 or 1; must signal target thread 5629 // That is, we can safely transition _Event from -1 to either 5630 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back 5631 // unpark() calls. 5632 // See also: "Semaphores in Plan 9" by Mullender & Cox 5633 // 5634 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5635 // that it will take two back-to-back park() calls for the owning 5636 // thread to block. This has the benefit of forcing a spurious return 5637 // from the first park() call after an unpark() call which will help 5638 // shake out uses of park() and unpark() without condition variables. 5639 5640 if (Atomic::xchg(1, &_Event) >= 0) return; 5641 5642 // Wait for the thread associated with the event to vacate 5643 int status = pthread_mutex_lock(_mutex); 5644 assert_status(status == 0, status, "mutex_lock"); 5645 int AnyWaiters = _nParked; 5646 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5647 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5648 AnyWaiters = 0; 5649 pthread_cond_signal(_cond); 5650 } 5651 status = pthread_mutex_unlock(_mutex); 5652 assert_status(status == 0, status, "mutex_unlock"); 5653 if (AnyWaiters != 0) { 5654 status = pthread_cond_signal(_cond); 5655 assert_status(status == 0, status, "cond_signal"); 5656 } 5657 5658 // Note that we signal() _after dropping the lock for "immortal" Events. 5659 // This is safe and avoids a common class of futile wakeups. In rare 5660 // circumstances this can cause a thread to return prematurely from 5661 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 5662 // simply re-test the condition and re-park itself. 5663 } 5664 5665 5666 // JSR166 5667 // ------------------------------------------------------- 5668 5669 /* 5670 * The solaris and linux implementations of park/unpark are fairly 5671 * conservative for now, but can be improved. They currently use a 5672 * mutex/condvar pair, plus a a count. 5673 * Park decrements count if > 0, else does a condvar wait. Unpark 5674 * sets count to 1 and signals condvar. Only one thread ever waits 5675 * on the condvar. Contention seen when trying to park implies that someone 5676 * is unparking you, so don't wait. And spurious returns are fine, so there 5677 * is no need to track notifications. 5678 */ 5679 5680 #define MAX_SECS 100000000 5681 /* 5682 * This code is common to linux and solaris and will be moved to a 5683 * common place in dolphin. 5684 * 5685 * The passed in time value is either a relative time in nanoseconds 5686 * or an absolute time in milliseconds. Either way it has to be unpacked 5687 * into suitable seconds and nanoseconds components and stored in the 5688 * given timespec structure. 5689 * Given time is a 64-bit value and the time_t used in the timespec is only 5690 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 5691 * overflow if times way in the future are given. Further on Solaris versions 5692 * prior to 10 there is a restriction (see cond_timedwait) that the specified 5693 * number of seconds, in abstime, is less than current_time + 100,000,000. 5694 * As it will be 28 years before "now + 100000000" will overflow we can 5695 * ignore overflow and just impose a hard-limit on seconds using the value 5696 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 5697 * years from "now". 5698 */ 5699 5700 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5701 assert (time > 0, "convertTime"); 5702 5703 struct timeval now; 5704 int status = gettimeofday(&now, NULL); 5705 assert(status == 0, "gettimeofday"); 5706 5707 time_t max_secs = now.tv_sec + MAX_SECS; 5708 5709 if (isAbsolute) { 5710 jlong secs = time / 1000; 5711 if (secs > max_secs) { 5712 absTime->tv_sec = max_secs; 5713 } 5714 else { 5715 absTime->tv_sec = secs; 5716 } 5717 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5718 } 5719 else { 5720 jlong secs = time / NANOSECS_PER_SEC; 5721 if (secs >= MAX_SECS) { 5722 absTime->tv_sec = max_secs; 5723 absTime->tv_nsec = 0; 5724 } 5725 else { 5726 absTime->tv_sec = now.tv_sec + secs; 5727 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5728 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5729 absTime->tv_nsec -= NANOSECS_PER_SEC; 5730 ++absTime->tv_sec; // note: this must be <= max_secs 5731 } 5732 } 5733 } 5734 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5735 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5736 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5737 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5738 } 5739 5740 void Parker::park(bool isAbsolute, jlong time) { 5741 // Ideally we'd do something useful while spinning, such 5742 // as calling unpackTime(). 5743 5744 // Optional fast-path check: 5745 // Return immediately if a permit is available. 5746 // We depend on Atomic::xchg() having full barrier semantics 5747 // since we are doing a lock-free update to _counter. 5748 if (Atomic::xchg(0, &_counter) > 0) return; 5749 5750 Thread* thread = Thread::current(); 5751 assert(thread->is_Java_thread(), "Must be JavaThread"); 5752 JavaThread *jt = (JavaThread *)thread; 5753 5754 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5755 // Check interrupt before trying to wait 5756 if (Thread::is_interrupted(thread, false)) { 5757 return; 5758 } 5759 5760 // Next, demultiplex/decode time arguments 5761 timespec absTime; 5762 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all 5763 return; 5764 } 5765 if (time > 0) { 5766 unpackTime(&absTime, isAbsolute, time); 5767 } 5768 5769 5770 // Enter safepoint region 5771 // Beware of deadlocks such as 6317397. 5772 // The per-thread Parker:: mutex is a classic leaf-lock. 5773 // In particular a thread must never block on the Threads_lock while 5774 // holding the Parker:: mutex. If safepoints are pending both the 5775 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5776 ThreadBlockInVM tbivm(jt); 5777 5778 // Don't wait if cannot get lock since interference arises from 5779 // unblocking. Also. check interrupt before trying wait 5780 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5781 return; 5782 } 5783 5784 int status ; 5785 if (_counter > 0) { // no wait needed 5786 _counter = 0; 5787 status = pthread_mutex_unlock(_mutex); 5788 assert (status == 0, "invariant") ; 5789 // Paranoia to ensure our locked and lock-free paths interact 5790 // correctly with each other and Java-level accesses. 5791 OrderAccess::fence(); 5792 return; 5793 } 5794 5795 #ifdef ASSERT 5796 // Don't catch signals while blocked; let the running threads have the signals. 5797 // (This allows a debugger to break into the running thread.) 5798 sigset_t oldsigs; 5799 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5800 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5801 #endif 5802 5803 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5804 jt->set_suspend_equivalent(); 5805 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5806 5807 if (time == 0) { 5808 status = pthread_cond_wait (_cond, _mutex) ; 5809 } else { 5810 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ; 5811 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5812 pthread_cond_destroy (_cond) ; 5813 pthread_cond_init (_cond, NULL); 5814 } 5815 } 5816 assert_status(status == 0 || status == EINTR || 5817 status == ETIME || status == ETIMEDOUT, 5818 status, "cond_timedwait"); 5819 5820 #ifdef ASSERT 5821 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5822 #endif 5823 5824 _counter = 0 ; 5825 status = pthread_mutex_unlock(_mutex) ; 5826 assert_status(status == 0, status, "invariant") ; 5827 // Paranoia to ensure our locked and lock-free paths interact 5828 // correctly with each other and Java-level accesses. 5829 OrderAccess::fence(); 5830 5831 // If externally suspended while waiting, re-suspend 5832 if (jt->handle_special_suspend_equivalent_condition()) { 5833 jt->java_suspend_self(); 5834 } 5835 } 5836 5837 void Parker::unpark() { 5838 int s, status ; 5839 status = pthread_mutex_lock(_mutex); 5840 assert (status == 0, "invariant") ; 5841 s = _counter; 5842 _counter = 1; 5843 if (s < 1) { 5844 if (WorkAroundNPTLTimedWaitHang) { 5845 status = pthread_cond_signal (_cond) ; 5846 assert (status == 0, "invariant") ; 5847 status = pthread_mutex_unlock(_mutex); 5848 assert (status == 0, "invariant") ; 5849 } else { 5850 status = pthread_mutex_unlock(_mutex); 5851 assert (status == 0, "invariant") ; 5852 status = pthread_cond_signal (_cond) ; 5853 assert (status == 0, "invariant") ; 5854 } 5855 } else { 5856 pthread_mutex_unlock(_mutex); 5857 assert (status == 0, "invariant") ; 5858 } 5859 } 5860 5861 5862 extern char** environ; 5863 5864 #ifndef __NR_fork 5865 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5866 #endif 5867 5868 #ifndef __NR_execve 5869 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 5870 #endif 5871 5872 // Run the specified command in a separate process. Return its exit value, 5873 // or -1 on failure (e.g. can't fork a new process). 5874 // Unlike system(), this function can be called from signal handler. It 5875 // doesn't block SIGINT et al. 5876 int os::fork_and_exec(char* cmd) { 5877 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5878 5879 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5880 // pthread_atfork handlers and reset pthread library. All we need is a 5881 // separate process to execve. Make a direct syscall to fork process. 5882 // On IA64 there's no fork syscall, we have to use fork() and hope for 5883 // the best... 5884 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5885 IA64_ONLY(fork();) 5886 5887 if (pid < 0) { 5888 // fork failed 5889 return -1; 5890 5891 } else if (pid == 0) { 5892 // child process 5893 5894 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5895 // first to kill every thread on the thread list. Because this list is 5896 // not reset by fork() (see notes above), execve() will instead kill 5897 // every thread in the parent process. We know this is the only thread 5898 // in the new process, so make a system call directly. 5899 // IA64 should use normal execve() from glibc to match the glibc fork() 5900 // above. 5901 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5902 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5903 5904 // execve failed 5905 _exit(-1); 5906 5907 } else { 5908 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5909 // care about the actual exit code, for now. 5910 5911 int status; 5912 5913 // Wait for the child process to exit. This returns immediately if 5914 // the child has already exited. */ 5915 while (waitpid(pid, &status, 0) < 0) { 5916 switch (errno) { 5917 case ECHILD: return 0; 5918 case EINTR: break; 5919 default: return -1; 5920 } 5921 } 5922 5923 if (WIFEXITED(status)) { 5924 // The child exited normally; get its exit code. 5925 return WEXITSTATUS(status); 5926 } else if (WIFSIGNALED(status)) { 5927 // The child exited because of a signal 5928 // The best value to return is 0x80 + signal number, 5929 // because that is what all Unix shells do, and because 5930 // it allows callers to distinguish between process exit and 5931 // process death by signal. 5932 return 0x80 + WTERMSIG(status); 5933 } else { 5934 // Unknown exit code; pass it through 5935 return status; 5936 } 5937 } 5938 } 5939 5940 // is_headless_jre() 5941 // 5942 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 5943 // in order to report if we are running in a headless jre 5944 // 5945 // Since JDK8 xawt/libmawt.so was moved into the same directory 5946 // as libawt.so, and renamed libawt_xawt.so 5947 // 5948 bool os::is_headless_jre() { 5949 struct stat statbuf; 5950 char buf[MAXPATHLEN]; 5951 char libmawtpath[MAXPATHLEN]; 5952 const char *xawtstr = "/xawt/libmawt.so"; 5953 const char *new_xawtstr = "/libawt_xawt.so"; 5954 char *p; 5955 5956 // Get path to libjvm.so 5957 os::jvm_path(buf, sizeof(buf)); 5958 5959 // Get rid of libjvm.so 5960 p = strrchr(buf, '/'); 5961 if (p == NULL) return false; 5962 else *p = '\0'; 5963 5964 // Get rid of client or server 5965 p = strrchr(buf, '/'); 5966 if (p == NULL) return false; 5967 else *p = '\0'; 5968 5969 // check xawt/libmawt.so 5970 strcpy(libmawtpath, buf); 5971 strcat(libmawtpath, xawtstr); 5972 if (::stat(libmawtpath, &statbuf) == 0) return false; 5973 5974 // check libawt_xawt.so 5975 strcpy(libmawtpath, buf); 5976 strcat(libmawtpath, new_xawtstr); 5977 if (::stat(libmawtpath, &statbuf) == 0) return false; 5978 5979 return true; 5980 } 5981 5982 // Get the default path to the core file 5983 // Returns the length of the string 5984 int os::get_core_path(char* buffer, size_t bufferSize) { 5985 const char* p = get_current_directory(buffer, bufferSize); 5986 5987 if (p == NULL) { 5988 assert(p != NULL, "failed to get current directory"); 5989 return 0; 5990 } 5991 5992 return strlen(buffer); 5993 } 5994 5995 #ifdef JAVASE_EMBEDDED 5996 // 5997 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory. 5998 // 5999 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL; 6000 6001 // ctor 6002 // 6003 MemNotifyThread::MemNotifyThread(int fd): Thread() { 6004 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread"); 6005 _fd = fd; 6006 6007 if (os::create_thread(this, os::os_thread)) { 6008 _memnotify_thread = this; 6009 os::set_priority(this, NearMaxPriority); 6010 os::start_thread(this); 6011 } 6012 } 6013 6014 // Where all the work gets done 6015 // 6016 void MemNotifyThread::run() { 6017 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread"); 6018 6019 // Set up the select arguments 6020 fd_set rfds; 6021 if (_fd != -1) { 6022 FD_ZERO(&rfds); 6023 FD_SET(_fd, &rfds); 6024 } 6025 6026 // Now wait for the mem_notify device to wake up 6027 while (1) { 6028 // Wait for the mem_notify device to signal us.. 6029 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL); 6030 if (rc == -1) { 6031 perror("select!\n"); 6032 break; 6033 } else if (rc) { 6034 //ssize_t free_before = os::available_memory(); 6035 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024); 6036 6037 // The kernel is telling us there is not much memory left... 6038 // try to do something about that 6039 6040 // If we are not already in a GC, try one. 6041 if (!Universe::heap()->is_gc_active()) { 6042 Universe::heap()->collect(GCCause::_allocation_failure); 6043 6044 //ssize_t free_after = os::available_memory(); 6045 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024); 6046 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024); 6047 } 6048 // We might want to do something like the following if we find the GC's are not helping... 6049 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true); 6050 } 6051 } 6052 } 6053 6054 // 6055 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it. 6056 // 6057 void MemNotifyThread::start() { 6058 int fd; 6059 fd = open ("/dev/mem_notify", O_RDONLY, 0); 6060 if (fd < 0) { 6061 return; 6062 } 6063 6064 if (memnotify_thread() == NULL) { 6065 new MemNotifyThread(fd); 6066 } 6067 } 6068 6069 #endif // JAVASE_EMBEDDED 6070 6071 6072 /////////////// Unit tests /////////////// 6073 6074 #ifndef PRODUCT 6075 6076 #define test_log(...) \ 6077 do {\ 6078 if (VerboseInternalVMTests) { \ 6079 tty->print_cr(__VA_ARGS__); \ 6080 tty->flush(); \ 6081 }\ 6082 } while (false) 6083 6084 class TestReserveMemorySpecial : AllStatic { 6085 public: 6086 static void small_page_write(void* addr, size_t size) { 6087 size_t page_size = os::vm_page_size(); 6088 6089 char* end = (char*)addr + size; 6090 for (char* p = (char*)addr; p < end; p += page_size) { 6091 *p = 1; 6092 } 6093 } 6094 6095 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6096 if (!UseHugeTLBFS) { 6097 return; 6098 } 6099 6100 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6101 6102 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6103 6104 if (addr != NULL) { 6105 small_page_write(addr, size); 6106 6107 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6108 } 6109 } 6110 6111 static void test_reserve_memory_special_huge_tlbfs_only() { 6112 if (!UseHugeTLBFS) { 6113 return; 6114 } 6115 6116 size_t lp = os::large_page_size(); 6117 6118 for (size_t size = lp; size <= lp * 10; size += lp) { 6119 test_reserve_memory_special_huge_tlbfs_only(size); 6120 } 6121 } 6122 6123 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) { 6124 if (!UseHugeTLBFS) { 6125 return; 6126 } 6127 6128 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")", 6129 size, alignment); 6130 6131 assert(size >= os::large_page_size(), "Incorrect input to test"); 6132 6133 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6134 6135 if (addr != NULL) { 6136 small_page_write(addr, size); 6137 6138 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6139 } 6140 } 6141 6142 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) { 6143 size_t lp = os::large_page_size(); 6144 size_t ag = os::vm_allocation_granularity(); 6145 6146 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6147 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment); 6148 } 6149 } 6150 6151 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6152 size_t lp = os::large_page_size(); 6153 size_t ag = os::vm_allocation_granularity(); 6154 6155 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp); 6156 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag); 6157 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2); 6158 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2); 6159 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag); 6160 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag); 6161 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2); 6162 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10); 6163 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2); 6164 } 6165 6166 static void test_reserve_memory_special_huge_tlbfs() { 6167 if (!UseHugeTLBFS) { 6168 return; 6169 } 6170 6171 test_reserve_memory_special_huge_tlbfs_only(); 6172 test_reserve_memory_special_huge_tlbfs_mixed(); 6173 } 6174 6175 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6176 if (!UseSHM) { 6177 return; 6178 } 6179 6180 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6181 6182 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6183 6184 if (addr != NULL) { 6185 assert(is_ptr_aligned(addr, alignment), "Check"); 6186 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6187 6188 small_page_write(addr, size); 6189 6190 os::Linux::release_memory_special_shm(addr, size); 6191 } 6192 } 6193 6194 static void test_reserve_memory_special_shm() { 6195 size_t lp = os::large_page_size(); 6196 size_t ag = os::vm_allocation_granularity(); 6197 6198 for (size_t size = ag; size < lp * 3; size += ag) { 6199 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6200 test_reserve_memory_special_shm(size, alignment); 6201 } 6202 } 6203 } 6204 6205 static void test() { 6206 test_reserve_memory_special_huge_tlbfs(); 6207 test_reserve_memory_special_shm(); 6208 } 6209 }; 6210 6211 void TestReserveMemorySpecial_test() { 6212 TestReserveMemorySpecial::test(); 6213 } 6214 6215 #endif