os_linux.cpp revision 4100:9fae07c31641
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/java.hpp" 48#include "runtime/javaCalls.hpp" 49#include "runtime/mutexLocker.hpp" 50#include "runtime/objectMonitor.hpp" 51#include "runtime/osThread.hpp" 52#include "runtime/perfMemory.hpp" 53#include "runtime/sharedRuntime.hpp" 54#include "runtime/statSampler.hpp" 55#include "runtime/stubRoutines.hpp" 56#include "runtime/thread.inline.hpp" 57#include "runtime/threadCritical.hpp" 58#include "runtime/timer.hpp" 59#include "services/attachListener.hpp" 60#include "services/runtimeService.hpp" 61#include "utilities/decoder.hpp" 62#include "utilities/defaultStream.hpp" 63#include "utilities/events.hpp" 64#include "utilities/growableArray.hpp" 65#include "utilities/vmError.hpp" 66 67// put OS-includes here 68# include <sys/types.h> 69# include <sys/mman.h> 70# include <sys/stat.h> 71# include <sys/select.h> 72# include <pthread.h> 73# include <signal.h> 74# include <errno.h> 75# include <dlfcn.h> 76# include <stdio.h> 77# include <unistd.h> 78# include <sys/resource.h> 79# include <pthread.h> 80# include <sys/stat.h> 81# include <sys/time.h> 82# include <sys/times.h> 83# include <sys/utsname.h> 84# include <sys/socket.h> 85# include <sys/wait.h> 86# include <pwd.h> 87# include <poll.h> 88# include <semaphore.h> 89# include <fcntl.h> 90# include <string.h> 91# include <syscall.h> 92# include <sys/sysinfo.h> 93# include <gnu/libc-version.h> 94# include <sys/ipc.h> 95# include <sys/shm.h> 96# include <link.h> 97# include <stdint.h> 98# include <inttypes.h> 99# include <sys/ioctl.h> 100 101#define MAX_PATH (2 * K) 102 103// for timer info max values which include all bits 104#define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 105 106#define LARGEPAGES_BIT (1 << 6) 107//////////////////////////////////////////////////////////////////////////////// 108// global variables 109julong os::Linux::_physical_memory = 0; 110 111address os::Linux::_initial_thread_stack_bottom = NULL; 112uintptr_t os::Linux::_initial_thread_stack_size = 0; 113 114int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 115int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 116Mutex* os::Linux::_createThread_lock = NULL; 117pthread_t os::Linux::_main_thread; 118int os::Linux::_page_size = -1; 119bool os::Linux::_is_floating_stack = false; 120bool os::Linux::_is_NPTL = false; 121bool os::Linux::_supports_fast_thread_cpu_time = false; 122const char * os::Linux::_glibc_version = NULL; 123const char * os::Linux::_libpthread_version = NULL; 124 125static jlong initial_time_count=0; 126 127static int clock_tics_per_sec = 100; 128 129// For diagnostics to print a message once. see run_periodic_checks 130static sigset_t check_signal_done; 131static bool check_signals = true;; 132 133static pid_t _initial_pid = 0; 134 135/* Signal number used to suspend/resume a thread */ 136 137/* do not use any signal number less than SIGSEGV, see 4355769 */ 138static int SR_signum = SIGUSR2; 139sigset_t SR_sigset; 140 141/* Used to protect dlsym() calls */ 142static pthread_mutex_t dl_mutex; 143 144#ifdef JAVASE_EMBEDDED 145class MemNotifyThread: public Thread { 146 friend class VMStructs; 147 public: 148 virtual void run(); 149 150 private: 151 static MemNotifyThread* _memnotify_thread; 152 int _fd; 153 154 public: 155 156 // Constructor 157 MemNotifyThread(int fd); 158 159 // Tester 160 bool is_memnotify_thread() const { return true; } 161 162 // Printing 163 char* name() const { return (char*)"Linux MemNotify Thread"; } 164 165 // Returns the single instance of the MemNotifyThread 166 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; } 167 168 // Create and start the single instance of MemNotifyThread 169 static void start(); 170}; 171#endif // JAVASE_EMBEDDED 172 173// utility functions 174 175static int SR_initialize(); 176static int SR_finalize(); 177 178julong os::available_memory() { 179 return Linux::available_memory(); 180} 181 182julong os::Linux::available_memory() { 183 // values in struct sysinfo are "unsigned long" 184 struct sysinfo si; 185 sysinfo(&si); 186 187 return (julong)si.freeram * si.mem_unit; 188} 189 190julong os::physical_memory() { 191 return Linux::physical_memory(); 192} 193 194julong os::allocatable_physical_memory(julong size) { 195#ifdef _LP64 196 return size; 197#else 198 julong result = MIN2(size, (julong)3800*M); 199 if (!is_allocatable(result)) { 200 // See comments under solaris for alignment considerations 201 julong reasonable_size = (julong)2*G - 2 * os::vm_page_size(); 202 result = MIN2(size, reasonable_size); 203 } 204 return result; 205#endif // _LP64 206} 207 208//////////////////////////////////////////////////////////////////////////////// 209// environment support 210 211bool os::getenv(const char* name, char* buf, int len) { 212 const char* val = ::getenv(name); 213 if (val != NULL && strlen(val) < (size_t)len) { 214 strcpy(buf, val); 215 return true; 216 } 217 if (len > 0) buf[0] = 0; // return a null string 218 return false; 219} 220 221 222// Return true if user is running as root. 223 224bool os::have_special_privileges() { 225 static bool init = false; 226 static bool privileges = false; 227 if (!init) { 228 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 229 init = true; 230 } 231 return privileges; 232} 233 234 235#ifndef SYS_gettid 236// i386: 224, ia64: 1105, amd64: 186, sparc 143 237#ifdef __ia64__ 238#define SYS_gettid 1105 239#elif __i386__ 240#define SYS_gettid 224 241#elif __amd64__ 242#define SYS_gettid 186 243#elif __sparc__ 244#define SYS_gettid 143 245#else 246#error define gettid for the arch 247#endif 248#endif 249 250// Cpu architecture string 251#if defined(ZERO) 252static char cpu_arch[] = ZERO_LIBARCH; 253#elif defined(IA64) 254static char cpu_arch[] = "ia64"; 255#elif defined(IA32) 256static char cpu_arch[] = "i386"; 257#elif defined(AMD64) 258static char cpu_arch[] = "amd64"; 259#elif defined(ARM) 260static char cpu_arch[] = "arm"; 261#elif defined(PPC) 262static char cpu_arch[] = "ppc"; 263#elif defined(SPARC) 264# ifdef _LP64 265static char cpu_arch[] = "sparcv9"; 266# else 267static char cpu_arch[] = "sparc"; 268# endif 269#else 270#error Add appropriate cpu_arch setting 271#endif 272 273 274// pid_t gettid() 275// 276// Returns the kernel thread id of the currently running thread. Kernel 277// thread id is used to access /proc. 278// 279// (Note that getpid() on LinuxThreads returns kernel thread id too; but 280// on NPTL, it returns the same pid for all threads, as required by POSIX.) 281// 282pid_t os::Linux::gettid() { 283 int rslt = syscall(SYS_gettid); 284 if (rslt == -1) { 285 // old kernel, no NPTL support 286 return getpid(); 287 } else { 288 return (pid_t)rslt; 289 } 290} 291 292// Most versions of linux have a bug where the number of processors are 293// determined by looking at the /proc file system. In a chroot environment, 294// the system call returns 1. This causes the VM to act as if it is 295// a single processor and elide locking (see is_MP() call). 296static bool unsafe_chroot_detected = false; 297static const char *unstable_chroot_error = "/proc file system not found.\n" 298 "Java may be unstable running multithreaded in a chroot " 299 "environment on Linux when /proc filesystem is not mounted."; 300 301void os::Linux::initialize_system_info() { 302 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 303 if (processor_count() == 1) { 304 pid_t pid = os::Linux::gettid(); 305 char fname[32]; 306 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 307 FILE *fp = fopen(fname, "r"); 308 if (fp == NULL) { 309 unsafe_chroot_detected = true; 310 } else { 311 fclose(fp); 312 } 313 } 314 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 315 assert(processor_count() > 0, "linux error"); 316} 317 318void os::init_system_properties_values() { 319// char arch[12]; 320// sysinfo(SI_ARCHITECTURE, arch, sizeof(arch)); 321 322 // The next steps are taken in the product version: 323 // 324 // Obtain the JAVA_HOME value from the location of libjvm.so. 325 // This library should be located at: 326 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 327 // 328 // If "/jre/lib/" appears at the right place in the path, then we 329 // assume libjvm.so is installed in a JDK and we use this path. 330 // 331 // Otherwise exit with message: "Could not create the Java virtual machine." 332 // 333 // The following extra steps are taken in the debugging version: 334 // 335 // If "/jre/lib/" does NOT appear at the right place in the path 336 // instead of exit check for $JAVA_HOME environment variable. 337 // 338 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 339 // then we append a fake suffix "hotspot/libjvm.so" to this path so 340 // it looks like libjvm.so is installed there 341 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 342 // 343 // Otherwise exit. 344 // 345 // Important note: if the location of libjvm.so changes this 346 // code needs to be changed accordingly. 347 348 // The next few definitions allow the code to be verbatim: 349#define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n), mtInternal) 350#define getenv(n) ::getenv(n) 351 352/* 353 * See ld(1): 354 * The linker uses the following search paths to locate required 355 * shared libraries: 356 * 1: ... 357 * ... 358 * 7: The default directories, normally /lib and /usr/lib. 359 */ 360#if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 361#define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 362#else 363#define DEFAULT_LIBPATH "/lib:/usr/lib" 364#endif 365 366#define EXTENSIONS_DIR "/lib/ext" 367#define ENDORSED_DIR "/lib/endorsed" 368#define REG_DIR "/usr/java/packages" 369 370 { 371 /* sysclasspath, java_home, dll_dir */ 372 { 373 char *home_path; 374 char *dll_path; 375 char *pslash; 376 char buf[MAXPATHLEN]; 377 os::jvm_path(buf, sizeof(buf)); 378 379 // Found the full path to libjvm.so. 380 // Now cut the path to <java_home>/jre if we can. 381 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */ 382 pslash = strrchr(buf, '/'); 383 if (pslash != NULL) 384 *pslash = '\0'; /* get rid of /{client|server|hotspot} */ 385 dll_path = malloc(strlen(buf) + 1); 386 if (dll_path == NULL) 387 return; 388 strcpy(dll_path, buf); 389 Arguments::set_dll_dir(dll_path); 390 391 if (pslash != NULL) { 392 pslash = strrchr(buf, '/'); 393 if (pslash != NULL) { 394 *pslash = '\0'; /* get rid of /<arch> */ 395 pslash = strrchr(buf, '/'); 396 if (pslash != NULL) 397 *pslash = '\0'; /* get rid of /lib */ 398 } 399 } 400 401 home_path = malloc(strlen(buf) + 1); 402 if (home_path == NULL) 403 return; 404 strcpy(home_path, buf); 405 Arguments::set_java_home(home_path); 406 407 if (!set_boot_path('/', ':')) 408 return; 409 } 410 411 /* 412 * Where to look for native libraries 413 * 414 * Note: Due to a legacy implementation, most of the library path 415 * is set in the launcher. This was to accomodate linking restrictions 416 * on legacy Linux implementations (which are no longer supported). 417 * Eventually, all the library path setting will be done here. 418 * 419 * However, to prevent the proliferation of improperly built native 420 * libraries, the new path component /usr/java/packages is added here. 421 * Eventually, all the library path setting will be done here. 422 */ 423 { 424 char *ld_library_path; 425 426 /* 427 * Construct the invariant part of ld_library_path. Note that the 428 * space for the colon and the trailing null are provided by the 429 * nulls included by the sizeof operator (so actually we allocate 430 * a byte more than necessary). 431 */ 432 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") + 433 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH)); 434 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch); 435 436 /* 437 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It 438 * should always exist (until the legacy problem cited above is 439 * addressed). 440 */ 441 char *v = getenv("LD_LIBRARY_PATH"); 442 if (v != NULL) { 443 char *t = ld_library_path; 444 /* That's +1 for the colon and +1 for the trailing '\0' */ 445 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1); 446 sprintf(ld_library_path, "%s:%s", v, t); 447 } 448 Arguments::set_library_path(ld_library_path); 449 } 450 451 /* 452 * Extensions directories. 453 * 454 * Note that the space for the colon and the trailing null are provided 455 * by the nulls included by the sizeof operator (so actually one byte more 456 * than necessary is allocated). 457 */ 458 { 459 char *buf = malloc(strlen(Arguments::get_java_home()) + 460 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR)); 461 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR, 462 Arguments::get_java_home()); 463 Arguments::set_ext_dirs(buf); 464 } 465 466 /* Endorsed standards default directory. */ 467 { 468 char * buf; 469 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR)); 470 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 471 Arguments::set_endorsed_dirs(buf); 472 } 473 } 474 475#undef malloc 476#undef getenv 477#undef EXTENSIONS_DIR 478#undef ENDORSED_DIR 479 480 // Done 481 return; 482} 483 484//////////////////////////////////////////////////////////////////////////////// 485// breakpoint support 486 487void os::breakpoint() { 488 BREAKPOINT; 489} 490 491extern "C" void breakpoint() { 492 // use debugger to set breakpoint here 493} 494 495//////////////////////////////////////////////////////////////////////////////// 496// signal support 497 498debug_only(static bool signal_sets_initialized = false); 499static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 500 501bool os::Linux::is_sig_ignored(int sig) { 502 struct sigaction oact; 503 sigaction(sig, (struct sigaction*)NULL, &oact); 504 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 505 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 506 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 507 return true; 508 else 509 return false; 510} 511 512void os::Linux::signal_sets_init() { 513 // Should also have an assertion stating we are still single-threaded. 514 assert(!signal_sets_initialized, "Already initialized"); 515 // Fill in signals that are necessarily unblocked for all threads in 516 // the VM. Currently, we unblock the following signals: 517 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 518 // by -Xrs (=ReduceSignalUsage)); 519 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 520 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 521 // the dispositions or masks wrt these signals. 522 // Programs embedding the VM that want to use the above signals for their 523 // own purposes must, at this time, use the "-Xrs" option to prevent 524 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 525 // (See bug 4345157, and other related bugs). 526 // In reality, though, unblocking these signals is really a nop, since 527 // these signals are not blocked by default. 528 sigemptyset(&unblocked_sigs); 529 sigemptyset(&allowdebug_blocked_sigs); 530 sigaddset(&unblocked_sigs, SIGILL); 531 sigaddset(&unblocked_sigs, SIGSEGV); 532 sigaddset(&unblocked_sigs, SIGBUS); 533 sigaddset(&unblocked_sigs, SIGFPE); 534 sigaddset(&unblocked_sigs, SR_signum); 535 536 if (!ReduceSignalUsage) { 537 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 538 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 539 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 540 } 541 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 542 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 543 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 544 } 545 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 546 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 547 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 548 } 549 } 550 // Fill in signals that are blocked by all but the VM thread. 551 sigemptyset(&vm_sigs); 552 if (!ReduceSignalUsage) 553 sigaddset(&vm_sigs, BREAK_SIGNAL); 554 debug_only(signal_sets_initialized = true); 555 556} 557 558// These are signals that are unblocked while a thread is running Java. 559// (For some reason, they get blocked by default.) 560sigset_t* os::Linux::unblocked_signals() { 561 assert(signal_sets_initialized, "Not initialized"); 562 return &unblocked_sigs; 563} 564 565// These are the signals that are blocked while a (non-VM) thread is 566// running Java. Only the VM thread handles these signals. 567sigset_t* os::Linux::vm_signals() { 568 assert(signal_sets_initialized, "Not initialized"); 569 return &vm_sigs; 570} 571 572// These are signals that are blocked during cond_wait to allow debugger in 573sigset_t* os::Linux::allowdebug_blocked_signals() { 574 assert(signal_sets_initialized, "Not initialized"); 575 return &allowdebug_blocked_sigs; 576} 577 578void os::Linux::hotspot_sigmask(Thread* thread) { 579 580 //Save caller's signal mask before setting VM signal mask 581 sigset_t caller_sigmask; 582 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 583 584 OSThread* osthread = thread->osthread(); 585 osthread->set_caller_sigmask(caller_sigmask); 586 587 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 588 589 if (!ReduceSignalUsage) { 590 if (thread->is_VM_thread()) { 591 // Only the VM thread handles BREAK_SIGNAL ... 592 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 593 } else { 594 // ... all other threads block BREAK_SIGNAL 595 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 596 } 597 } 598} 599 600////////////////////////////////////////////////////////////////////////////// 601// detecting pthread library 602 603void os::Linux::libpthread_init() { 604 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 605 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 606 // generic name for earlier versions. 607 // Define macros here so we can build HotSpot on old systems. 608# ifndef _CS_GNU_LIBC_VERSION 609# define _CS_GNU_LIBC_VERSION 2 610# endif 611# ifndef _CS_GNU_LIBPTHREAD_VERSION 612# define _CS_GNU_LIBPTHREAD_VERSION 3 613# endif 614 615 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 616 if (n > 0) { 617 char *str = (char *)malloc(n, mtInternal); 618 confstr(_CS_GNU_LIBC_VERSION, str, n); 619 os::Linux::set_glibc_version(str); 620 } else { 621 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 622 static char _gnu_libc_version[32]; 623 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 624 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 625 os::Linux::set_glibc_version(_gnu_libc_version); 626 } 627 628 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 629 if (n > 0) { 630 char *str = (char *)malloc(n, mtInternal); 631 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 632 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 633 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 634 // is the case. LinuxThreads has a hard limit on max number of threads. 635 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 636 // On the other hand, NPTL does not have such a limit, sysconf() 637 // will return -1 and errno is not changed. Check if it is really NPTL. 638 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 639 strstr(str, "NPTL") && 640 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 641 free(str); 642 os::Linux::set_libpthread_version("linuxthreads"); 643 } else { 644 os::Linux::set_libpthread_version(str); 645 } 646 } else { 647 // glibc before 2.3.2 only has LinuxThreads. 648 os::Linux::set_libpthread_version("linuxthreads"); 649 } 650 651 if (strstr(libpthread_version(), "NPTL")) { 652 os::Linux::set_is_NPTL(); 653 } else { 654 os::Linux::set_is_LinuxThreads(); 655 } 656 657 // LinuxThreads have two flavors: floating-stack mode, which allows variable 658 // stack size; and fixed-stack mode. NPTL is always floating-stack. 659 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 660 os::Linux::set_is_floating_stack(); 661 } 662} 663 664///////////////////////////////////////////////////////////////////////////// 665// thread stack 666 667// Force Linux kernel to expand current thread stack. If "bottom" is close 668// to the stack guard, caller should block all signals. 669// 670// MAP_GROWSDOWN: 671// A special mmap() flag that is used to implement thread stacks. It tells 672// kernel that the memory region should extend downwards when needed. This 673// allows early versions of LinuxThreads to only mmap the first few pages 674// when creating a new thread. Linux kernel will automatically expand thread 675// stack as needed (on page faults). 676// 677// However, because the memory region of a MAP_GROWSDOWN stack can grow on 678// demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 679// region, it's hard to tell if the fault is due to a legitimate stack 680// access or because of reading/writing non-exist memory (e.g. buffer 681// overrun). As a rule, if the fault happens below current stack pointer, 682// Linux kernel does not expand stack, instead a SIGSEGV is sent to the 683// application (see Linux kernel fault.c). 684// 685// This Linux feature can cause SIGSEGV when VM bangs thread stack for 686// stack overflow detection. 687// 688// Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 689// not use this flag. However, the stack of initial thread is not created 690// by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 691// unlikely) that user code can create a thread with MAP_GROWSDOWN stack 692// and then attach the thread to JVM. 693// 694// To get around the problem and allow stack banging on Linux, we need to 695// manually expand thread stack after receiving the SIGSEGV. 696// 697// There are two ways to expand thread stack to address "bottom", we used 698// both of them in JVM before 1.5: 699// 1. adjust stack pointer first so that it is below "bottom", and then 700// touch "bottom" 701// 2. mmap() the page in question 702// 703// Now alternate signal stack is gone, it's harder to use 2. For instance, 704// if current sp is already near the lower end of page 101, and we need to 705// call mmap() to map page 100, it is possible that part of the mmap() frame 706// will be placed in page 100. When page 100 is mapped, it is zero-filled. 707// That will destroy the mmap() frame and cause VM to crash. 708// 709// The following code works by adjusting sp first, then accessing the "bottom" 710// page to force a page fault. Linux kernel will then automatically expand the 711// stack mapping. 712// 713// _expand_stack_to() assumes its frame size is less than page size, which 714// should always be true if the function is not inlined. 715 716#if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 717#define NOINLINE 718#else 719#define NOINLINE __attribute__ ((noinline)) 720#endif 721 722static void _expand_stack_to(address bottom) NOINLINE; 723 724static void _expand_stack_to(address bottom) { 725 address sp; 726 size_t size; 727 volatile char *p; 728 729 // Adjust bottom to point to the largest address within the same page, it 730 // gives us a one-page buffer if alloca() allocates slightly more memory. 731 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 732 bottom += os::Linux::page_size() - 1; 733 734 // sp might be slightly above current stack pointer; if that's the case, we 735 // will alloca() a little more space than necessary, which is OK. Don't use 736 // os::current_stack_pointer(), as its result can be slightly below current 737 // stack pointer, causing us to not alloca enough to reach "bottom". 738 sp = (address)&sp; 739 740 if (sp > bottom) { 741 size = sp - bottom; 742 p = (volatile char *)alloca(size); 743 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 744 p[0] = '\0'; 745 } 746} 747 748bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 749 assert(t!=NULL, "just checking"); 750 assert(t->osthread()->expanding_stack(), "expand should be set"); 751 assert(t->stack_base() != NULL, "stack_base was not initialized"); 752 753 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 754 sigset_t mask_all, old_sigset; 755 sigfillset(&mask_all); 756 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 757 _expand_stack_to(addr); 758 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 759 return true; 760 } 761 return false; 762} 763 764////////////////////////////////////////////////////////////////////////////// 765// create new thread 766 767static address highest_vm_reserved_address(); 768 769// check if it's safe to start a new thread 770static bool _thread_safety_check(Thread* thread) { 771 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 772 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 773 // Heap is mmap'ed at lower end of memory space. Thread stacks are 774 // allocated (MAP_FIXED) from high address space. Every thread stack 775 // occupies a fixed size slot (usually 2Mbytes, but user can change 776 // it to other values if they rebuild LinuxThreads). 777 // 778 // Problem with MAP_FIXED is that mmap() can still succeed even part of 779 // the memory region has already been mmap'ed. That means if we have too 780 // many threads and/or very large heap, eventually thread stack will 781 // collide with heap. 782 // 783 // Here we try to prevent heap/stack collision by comparing current 784 // stack bottom with the highest address that has been mmap'ed by JVM 785 // plus a safety margin for memory maps created by native code. 786 // 787 // This feature can be disabled by setting ThreadSafetyMargin to 0 788 // 789 if (ThreadSafetyMargin > 0) { 790 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 791 792 // not safe if our stack extends below the safety margin 793 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 794 } else { 795 return true; 796 } 797 } else { 798 // Floating stack LinuxThreads or NPTL: 799 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 800 // there's not enough space left, pthread_create() will fail. If we come 801 // here, that means enough space has been reserved for stack. 802 return true; 803 } 804} 805 806// Thread start routine for all newly created threads 807static void *java_start(Thread *thread) { 808 // Try to randomize the cache line index of hot stack frames. 809 // This helps when threads of the same stack traces evict each other's 810 // cache lines. The threads can be either from the same JVM instance, or 811 // from different JVM instances. The benefit is especially true for 812 // processors with hyperthreading technology. 813 static int counter = 0; 814 int pid = os::current_process_id(); 815 alloca(((pid ^ counter++) & 7) * 128); 816 817 ThreadLocalStorage::set_thread(thread); 818 819 OSThread* osthread = thread->osthread(); 820 Monitor* sync = osthread->startThread_lock(); 821 822 // non floating stack LinuxThreads needs extra check, see above 823 if (!_thread_safety_check(thread)) { 824 // notify parent thread 825 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 826 osthread->set_state(ZOMBIE); 827 sync->notify_all(); 828 return NULL; 829 } 830 831 // thread_id is kernel thread id (similar to Solaris LWP id) 832 osthread->set_thread_id(os::Linux::gettid()); 833 834 if (UseNUMA) { 835 int lgrp_id = os::numa_get_group_id(); 836 if (lgrp_id != -1) { 837 thread->set_lgrp_id(lgrp_id); 838 } 839 } 840 // initialize signal mask for this thread 841 os::Linux::hotspot_sigmask(thread); 842 843 // initialize floating point control register 844 os::Linux::init_thread_fpu_state(); 845 846 // handshaking with parent thread 847 { 848 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 849 850 // notify parent thread 851 osthread->set_state(INITIALIZED); 852 sync->notify_all(); 853 854 // wait until os::start_thread() 855 while (osthread->get_state() == INITIALIZED) { 856 sync->wait(Mutex::_no_safepoint_check_flag); 857 } 858 } 859 860 // call one more level start routine 861 thread->run(); 862 863 return 0; 864} 865 866bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 867 assert(thread->osthread() == NULL, "caller responsible"); 868 869 // Allocate the OSThread object 870 OSThread* osthread = new OSThread(NULL, NULL); 871 if (osthread == NULL) { 872 return false; 873 } 874 875 // set the correct thread state 876 osthread->set_thread_type(thr_type); 877 878 // Initial state is ALLOCATED but not INITIALIZED 879 osthread->set_state(ALLOCATED); 880 881 thread->set_osthread(osthread); 882 883 // init thread attributes 884 pthread_attr_t attr; 885 pthread_attr_init(&attr); 886 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 887 888 // stack size 889 if (os::Linux::supports_variable_stack_size()) { 890 // calculate stack size if it's not specified by caller 891 if (stack_size == 0) { 892 stack_size = os::Linux::default_stack_size(thr_type); 893 894 switch (thr_type) { 895 case os::java_thread: 896 // Java threads use ThreadStackSize which default value can be 897 // changed with the flag -Xss 898 assert (JavaThread::stack_size_at_create() > 0, "this should be set"); 899 stack_size = JavaThread::stack_size_at_create(); 900 break; 901 case os::compiler_thread: 902 if (CompilerThreadStackSize > 0) { 903 stack_size = (size_t)(CompilerThreadStackSize * K); 904 break; 905 } // else fall through: 906 // use VMThreadStackSize if CompilerThreadStackSize is not defined 907 case os::vm_thread: 908 case os::pgc_thread: 909 case os::cgc_thread: 910 case os::watcher_thread: 911 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 912 break; 913 } 914 } 915 916 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 917 pthread_attr_setstacksize(&attr, stack_size); 918 } else { 919 // let pthread_create() pick the default value. 920 } 921 922 // glibc guard page 923 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 924 925 ThreadState state; 926 927 { 928 // Serialize thread creation if we are running with fixed stack LinuxThreads 929 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 930 if (lock) { 931 os::Linux::createThread_lock()->lock_without_safepoint_check(); 932 } 933 934 pthread_t tid; 935 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 936 937 pthread_attr_destroy(&attr); 938 939 if (ret != 0) { 940 if (PrintMiscellaneous && (Verbose || WizardMode)) { 941 perror("pthread_create()"); 942 } 943 // Need to clean up stuff we've allocated so far 944 thread->set_osthread(NULL); 945 delete osthread; 946 if (lock) os::Linux::createThread_lock()->unlock(); 947 return false; 948 } 949 950 // Store pthread info into the OSThread 951 osthread->set_pthread_id(tid); 952 953 // Wait until child thread is either initialized or aborted 954 { 955 Monitor* sync_with_child = osthread->startThread_lock(); 956 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 957 while ((state = osthread->get_state()) == ALLOCATED) { 958 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 959 } 960 } 961 962 if (lock) { 963 os::Linux::createThread_lock()->unlock(); 964 } 965 } 966 967 // Aborted due to thread limit being reached 968 if (state == ZOMBIE) { 969 thread->set_osthread(NULL); 970 delete osthread; 971 return false; 972 } 973 974 // The thread is returned suspended (in state INITIALIZED), 975 // and is started higher up in the call chain 976 assert(state == INITIALIZED, "race condition"); 977 return true; 978} 979 980///////////////////////////////////////////////////////////////////////////// 981// attach existing thread 982 983// bootstrap the main thread 984bool os::create_main_thread(JavaThread* thread) { 985 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 986 return create_attached_thread(thread); 987} 988 989bool os::create_attached_thread(JavaThread* thread) { 990#ifdef ASSERT 991 thread->verify_not_published(); 992#endif 993 994 // Allocate the OSThread object 995 OSThread* osthread = new OSThread(NULL, NULL); 996 997 if (osthread == NULL) { 998 return false; 999 } 1000 1001 // Store pthread info into the OSThread 1002 osthread->set_thread_id(os::Linux::gettid()); 1003 osthread->set_pthread_id(::pthread_self()); 1004 1005 // initialize floating point control register 1006 os::Linux::init_thread_fpu_state(); 1007 1008 // Initial thread state is RUNNABLE 1009 osthread->set_state(RUNNABLE); 1010 1011 thread->set_osthread(osthread); 1012 1013 if (UseNUMA) { 1014 int lgrp_id = os::numa_get_group_id(); 1015 if (lgrp_id != -1) { 1016 thread->set_lgrp_id(lgrp_id); 1017 } 1018 } 1019 1020 if (os::Linux::is_initial_thread()) { 1021 // If current thread is initial thread, its stack is mapped on demand, 1022 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 1023 // the entire stack region to avoid SEGV in stack banging. 1024 // It is also useful to get around the heap-stack-gap problem on SuSE 1025 // kernel (see 4821821 for details). We first expand stack to the top 1026 // of yellow zone, then enable stack yellow zone (order is significant, 1027 // enabling yellow zone first will crash JVM on SuSE Linux), so there 1028 // is no gap between the last two virtual memory regions. 1029 1030 JavaThread *jt = (JavaThread *)thread; 1031 address addr = jt->stack_yellow_zone_base(); 1032 assert(addr != NULL, "initialization problem?"); 1033 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 1034 1035 osthread->set_expanding_stack(); 1036 os::Linux::manually_expand_stack(jt, addr); 1037 osthread->clear_expanding_stack(); 1038 } 1039 1040 // initialize signal mask for this thread 1041 // and save the caller's signal mask 1042 os::Linux::hotspot_sigmask(thread); 1043 1044 return true; 1045} 1046 1047void os::pd_start_thread(Thread* thread) { 1048 OSThread * osthread = thread->osthread(); 1049 assert(osthread->get_state() != INITIALIZED, "just checking"); 1050 Monitor* sync_with_child = osthread->startThread_lock(); 1051 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 1052 sync_with_child->notify(); 1053} 1054 1055// Free Linux resources related to the OSThread 1056void os::free_thread(OSThread* osthread) { 1057 assert(osthread != NULL, "osthread not set"); 1058 1059 if (Thread::current()->osthread() == osthread) { 1060 // Restore caller's signal mask 1061 sigset_t sigmask = osthread->caller_sigmask(); 1062 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1063 } 1064 1065 delete osthread; 1066} 1067 1068////////////////////////////////////////////////////////////////////////////// 1069// thread local storage 1070 1071int os::allocate_thread_local_storage() { 1072 pthread_key_t key; 1073 int rslt = pthread_key_create(&key, NULL); 1074 assert(rslt == 0, "cannot allocate thread local storage"); 1075 return (int)key; 1076} 1077 1078// Note: This is currently not used by VM, as we don't destroy TLS key 1079// on VM exit. 1080void os::free_thread_local_storage(int index) { 1081 int rslt = pthread_key_delete((pthread_key_t)index); 1082 assert(rslt == 0, "invalid index"); 1083} 1084 1085void os::thread_local_storage_at_put(int index, void* value) { 1086 int rslt = pthread_setspecific((pthread_key_t)index, value); 1087 assert(rslt == 0, "pthread_setspecific failed"); 1088} 1089 1090extern "C" Thread* get_thread() { 1091 return ThreadLocalStorage::thread(); 1092} 1093 1094////////////////////////////////////////////////////////////////////////////// 1095// initial thread 1096 1097// Check if current thread is the initial thread, similar to Solaris thr_main. 1098bool os::Linux::is_initial_thread(void) { 1099 char dummy; 1100 // If called before init complete, thread stack bottom will be null. 1101 // Can be called if fatal error occurs before initialization. 1102 if (initial_thread_stack_bottom() == NULL) return false; 1103 assert(initial_thread_stack_bottom() != NULL && 1104 initial_thread_stack_size() != 0, 1105 "os::init did not locate initial thread's stack region"); 1106 if ((address)&dummy >= initial_thread_stack_bottom() && 1107 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1108 return true; 1109 else return false; 1110} 1111 1112// Find the virtual memory area that contains addr 1113static bool find_vma(address addr, address* vma_low, address* vma_high) { 1114 FILE *fp = fopen("/proc/self/maps", "r"); 1115 if (fp) { 1116 address low, high; 1117 while (!feof(fp)) { 1118 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1119 if (low <= addr && addr < high) { 1120 if (vma_low) *vma_low = low; 1121 if (vma_high) *vma_high = high; 1122 fclose (fp); 1123 return true; 1124 } 1125 } 1126 for (;;) { 1127 int ch = fgetc(fp); 1128 if (ch == EOF || ch == (int)'\n') break; 1129 } 1130 } 1131 fclose(fp); 1132 } 1133 return false; 1134} 1135 1136// Locate initial thread stack. This special handling of initial thread stack 1137// is needed because pthread_getattr_np() on most (all?) Linux distros returns 1138// bogus value for initial thread. 1139void os::Linux::capture_initial_stack(size_t max_size) { 1140 // stack size is the easy part, get it from RLIMIT_STACK 1141 size_t stack_size; 1142 struct rlimit rlim; 1143 getrlimit(RLIMIT_STACK, &rlim); 1144 stack_size = rlim.rlim_cur; 1145 1146 // 6308388: a bug in ld.so will relocate its own .data section to the 1147 // lower end of primordial stack; reduce ulimit -s value a little bit 1148 // so we won't install guard page on ld.so's data section. 1149 stack_size -= 2 * page_size(); 1150 1151 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1152 // 7.1, in both cases we will get 2G in return value. 1153 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1154 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1155 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1156 // in case other parts in glibc still assumes 2M max stack size. 1157 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1158 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1159 if (stack_size > 2 * K * K IA64_ONLY(*2)) 1160 stack_size = 2 * K * K IA64_ONLY(*2); 1161 // Try to figure out where the stack base (top) is. This is harder. 1162 // 1163 // When an application is started, glibc saves the initial stack pointer in 1164 // a global variable "__libc_stack_end", which is then used by system 1165 // libraries. __libc_stack_end should be pretty close to stack top. The 1166 // variable is available since the very early days. However, because it is 1167 // a private interface, it could disappear in the future. 1168 // 1169 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1170 // to __libc_stack_end, it is very close to stack top, but isn't the real 1171 // stack top. Note that /proc may not exist if VM is running as a chroot 1172 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1173 // /proc/<pid>/stat could change in the future (though unlikely). 1174 // 1175 // We try __libc_stack_end first. If that doesn't work, look for 1176 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1177 // as a hint, which should work well in most cases. 1178 1179 uintptr_t stack_start; 1180 1181 // try __libc_stack_end first 1182 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1183 if (p && *p) { 1184 stack_start = *p; 1185 } else { 1186 // see if we can get the start_stack field from /proc/self/stat 1187 FILE *fp; 1188 int pid; 1189 char state; 1190 int ppid; 1191 int pgrp; 1192 int session; 1193 int nr; 1194 int tpgrp; 1195 unsigned long flags; 1196 unsigned long minflt; 1197 unsigned long cminflt; 1198 unsigned long majflt; 1199 unsigned long cmajflt; 1200 unsigned long utime; 1201 unsigned long stime; 1202 long cutime; 1203 long cstime; 1204 long prio; 1205 long nice; 1206 long junk; 1207 long it_real; 1208 uintptr_t start; 1209 uintptr_t vsize; 1210 intptr_t rss; 1211 uintptr_t rsslim; 1212 uintptr_t scodes; 1213 uintptr_t ecode; 1214 int i; 1215 1216 // Figure what the primordial thread stack base is. Code is inspired 1217 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1218 // followed by command name surrounded by parentheses, state, etc. 1219 char stat[2048]; 1220 int statlen; 1221 1222 fp = fopen("/proc/self/stat", "r"); 1223 if (fp) { 1224 statlen = fread(stat, 1, 2047, fp); 1225 stat[statlen] = '\0'; 1226 fclose(fp); 1227 1228 // Skip pid and the command string. Note that we could be dealing with 1229 // weird command names, e.g. user could decide to rename java launcher 1230 // to "java 1.4.2 :)", then the stat file would look like 1231 // 1234 (java 1.4.2 :)) R ... ... 1232 // We don't really need to know the command string, just find the last 1233 // occurrence of ")" and then start parsing from there. See bug 4726580. 1234 char * s = strrchr(stat, ')'); 1235 1236 i = 0; 1237 if (s) { 1238 // Skip blank chars 1239 do s++; while (isspace(*s)); 1240 1241#define _UFM UINTX_FORMAT 1242#define _DFM INTX_FORMAT 1243 1244 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1245 /* 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 */ 1246 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, 1247 &state, /* 3 %c */ 1248 &ppid, /* 4 %d */ 1249 &pgrp, /* 5 %d */ 1250 &session, /* 6 %d */ 1251 &nr, /* 7 %d */ 1252 &tpgrp, /* 8 %d */ 1253 &flags, /* 9 %lu */ 1254 &minflt, /* 10 %lu */ 1255 &cminflt, /* 11 %lu */ 1256 &majflt, /* 12 %lu */ 1257 &cmajflt, /* 13 %lu */ 1258 &utime, /* 14 %lu */ 1259 &stime, /* 15 %lu */ 1260 &cutime, /* 16 %ld */ 1261 &cstime, /* 17 %ld */ 1262 &prio, /* 18 %ld */ 1263 &nice, /* 19 %ld */ 1264 &junk, /* 20 %ld */ 1265 &it_real, /* 21 %ld */ 1266 &start, /* 22 UINTX_FORMAT */ 1267 &vsize, /* 23 UINTX_FORMAT */ 1268 &rss, /* 24 INTX_FORMAT */ 1269 &rsslim, /* 25 UINTX_FORMAT */ 1270 &scodes, /* 26 UINTX_FORMAT */ 1271 &ecode, /* 27 UINTX_FORMAT */ 1272 &stack_start); /* 28 UINTX_FORMAT */ 1273 } 1274 1275#undef _UFM 1276#undef _DFM 1277 1278 if (i != 28 - 2) { 1279 assert(false, "Bad conversion from /proc/self/stat"); 1280 // product mode - assume we are the initial thread, good luck in the 1281 // embedded case. 1282 warning("Can't detect initial thread stack location - bad conversion"); 1283 stack_start = (uintptr_t) &rlim; 1284 } 1285 } else { 1286 // For some reason we can't open /proc/self/stat (for example, running on 1287 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1288 // most cases, so don't abort: 1289 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1290 stack_start = (uintptr_t) &rlim; 1291 } 1292 } 1293 1294 // Now we have a pointer (stack_start) very close to the stack top, the 1295 // next thing to do is to figure out the exact location of stack top. We 1296 // can find out the virtual memory area that contains stack_start by 1297 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1298 // and its upper limit is the real stack top. (again, this would fail if 1299 // running inside chroot, because /proc may not exist.) 1300 1301 uintptr_t stack_top; 1302 address low, high; 1303 if (find_vma((address)stack_start, &low, &high)) { 1304 // success, "high" is the true stack top. (ignore "low", because initial 1305 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1306 stack_top = (uintptr_t)high; 1307 } else { 1308 // failed, likely because /proc/self/maps does not exist 1309 warning("Can't detect initial thread stack location - find_vma failed"); 1310 // best effort: stack_start is normally within a few pages below the real 1311 // stack top, use it as stack top, and reduce stack size so we won't put 1312 // guard page outside stack. 1313 stack_top = stack_start; 1314 stack_size -= 16 * page_size(); 1315 } 1316 1317 // stack_top could be partially down the page so align it 1318 stack_top = align_size_up(stack_top, page_size()); 1319 1320 if (max_size && stack_size > max_size) { 1321 _initial_thread_stack_size = max_size; 1322 } else { 1323 _initial_thread_stack_size = stack_size; 1324 } 1325 1326 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1327 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1328} 1329 1330//////////////////////////////////////////////////////////////////////////////// 1331// time support 1332 1333// Time since start-up in seconds to a fine granularity. 1334// Used by VMSelfDestructTimer and the MemProfiler. 1335double os::elapsedTime() { 1336 1337 return (double)(os::elapsed_counter()) * 0.000001; 1338} 1339 1340jlong os::elapsed_counter() { 1341 timeval time; 1342 int status = gettimeofday(&time, NULL); 1343 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count; 1344} 1345 1346jlong os::elapsed_frequency() { 1347 return (1000 * 1000); 1348} 1349 1350// For now, we say that linux does not support vtime. I have no idea 1351// whether it can actually be made to (DLD, 9/13/05). 1352 1353bool os::supports_vtime() { return false; } 1354bool os::enable_vtime() { return false; } 1355bool os::vtime_enabled() { return false; } 1356double os::elapsedVTime() { 1357 // better than nothing, but not much 1358 return elapsedTime(); 1359} 1360 1361jlong os::javaTimeMillis() { 1362 timeval time; 1363 int status = gettimeofday(&time, NULL); 1364 assert(status != -1, "linux error"); 1365 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1366} 1367 1368#ifndef CLOCK_MONOTONIC 1369#define CLOCK_MONOTONIC (1) 1370#endif 1371 1372void os::Linux::clock_init() { 1373 // we do dlopen's in this particular order due to bug in linux 1374 // dynamical loader (see 6348968) leading to crash on exit 1375 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1376 if (handle == NULL) { 1377 handle = dlopen("librt.so", RTLD_LAZY); 1378 } 1379 1380 if (handle) { 1381 int (*clock_getres_func)(clockid_t, struct timespec*) = 1382 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1383 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1384 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1385 if (clock_getres_func && clock_gettime_func) { 1386 // See if monotonic clock is supported by the kernel. Note that some 1387 // early implementations simply return kernel jiffies (updated every 1388 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1389 // for nano time (though the monotonic property is still nice to have). 1390 // It's fixed in newer kernels, however clock_getres() still returns 1391 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1392 // resolution for now. Hopefully as people move to new kernels, this 1393 // won't be a problem. 1394 struct timespec res; 1395 struct timespec tp; 1396 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1397 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1398 // yes, monotonic clock is supported 1399 _clock_gettime = clock_gettime_func; 1400 } else { 1401 // close librt if there is no monotonic clock 1402 dlclose(handle); 1403 } 1404 } 1405 } 1406} 1407 1408#ifndef SYS_clock_getres 1409 1410#if defined(IA32) || defined(AMD64) 1411#define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1412#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1413#else 1414#warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1415#define sys_clock_getres(x,y) -1 1416#endif 1417 1418#else 1419#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1420#endif 1421 1422void os::Linux::fast_thread_clock_init() { 1423 if (!UseLinuxPosixThreadCPUClocks) { 1424 return; 1425 } 1426 clockid_t clockid; 1427 struct timespec tp; 1428 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1429 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1430 1431 // Switch to using fast clocks for thread cpu time if 1432 // the sys_clock_getres() returns 0 error code. 1433 // Note, that some kernels may support the current thread 1434 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1435 // returned by the pthread_getcpuclockid(). 1436 // If the fast Posix clocks are supported then the sys_clock_getres() 1437 // must return at least tp.tv_sec == 0 which means a resolution 1438 // better than 1 sec. This is extra check for reliability. 1439 1440 if(pthread_getcpuclockid_func && 1441 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1442 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1443 1444 _supports_fast_thread_cpu_time = true; 1445 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1446 } 1447} 1448 1449jlong os::javaTimeNanos() { 1450 if (Linux::supports_monotonic_clock()) { 1451 struct timespec tp; 1452 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1453 assert(status == 0, "gettime error"); 1454 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1455 return result; 1456 } else { 1457 timeval time; 1458 int status = gettimeofday(&time, NULL); 1459 assert(status != -1, "linux error"); 1460 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1461 return 1000 * usecs; 1462 } 1463} 1464 1465void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1466 if (Linux::supports_monotonic_clock()) { 1467 info_ptr->max_value = ALL_64_BITS; 1468 1469 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1470 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1471 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1472 } else { 1473 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1474 info_ptr->max_value = ALL_64_BITS; 1475 1476 // gettimeofday is a real time clock so it skips 1477 info_ptr->may_skip_backward = true; 1478 info_ptr->may_skip_forward = true; 1479 } 1480 1481 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1482} 1483 1484// Return the real, user, and system times in seconds from an 1485// arbitrary fixed point in the past. 1486bool os::getTimesSecs(double* process_real_time, 1487 double* process_user_time, 1488 double* process_system_time) { 1489 struct tms ticks; 1490 clock_t real_ticks = times(&ticks); 1491 1492 if (real_ticks == (clock_t) (-1)) { 1493 return false; 1494 } else { 1495 double ticks_per_second = (double) clock_tics_per_sec; 1496 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1497 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1498 *process_real_time = ((double) real_ticks) / ticks_per_second; 1499 1500 return true; 1501 } 1502} 1503 1504 1505char * os::local_time_string(char *buf, size_t buflen) { 1506 struct tm t; 1507 time_t long_time; 1508 time(&long_time); 1509 localtime_r(&long_time, &t); 1510 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1511 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1512 t.tm_hour, t.tm_min, t.tm_sec); 1513 return buf; 1514} 1515 1516struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1517 return localtime_r(clock, res); 1518} 1519 1520//////////////////////////////////////////////////////////////////////////////// 1521// runtime exit support 1522 1523// Note: os::shutdown() might be called very early during initialization, or 1524// called from signal handler. Before adding something to os::shutdown(), make 1525// sure it is async-safe and can handle partially initialized VM. 1526void os::shutdown() { 1527 1528 // allow PerfMemory to attempt cleanup of any persistent resources 1529 perfMemory_exit(); 1530 1531 // needs to remove object in file system 1532 AttachListener::abort(); 1533 1534 // flush buffered output, finish log files 1535 ostream_abort(); 1536 1537 // Check for abort hook 1538 abort_hook_t abort_hook = Arguments::abort_hook(); 1539 if (abort_hook != NULL) { 1540 abort_hook(); 1541 } 1542 1543} 1544 1545// Note: os::abort() might be called very early during initialization, or 1546// called from signal handler. Before adding something to os::abort(), make 1547// sure it is async-safe and can handle partially initialized VM. 1548void os::abort(bool dump_core) { 1549 os::shutdown(); 1550 if (dump_core) { 1551#ifndef PRODUCT 1552 fdStream out(defaultStream::output_fd()); 1553 out.print_raw("Current thread is "); 1554 char buf[16]; 1555 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1556 out.print_raw_cr(buf); 1557 out.print_raw_cr("Dumping core ..."); 1558#endif 1559 ::abort(); // dump core 1560 } 1561 1562 ::exit(1); 1563} 1564 1565// Die immediately, no exit hook, no abort hook, no cleanup. 1566void os::die() { 1567 // _exit() on LinuxThreads only kills current thread 1568 ::abort(); 1569} 1570 1571// unused on linux for now. 1572void os::set_error_file(const char *logfile) {} 1573 1574 1575// This method is a copy of JDK's sysGetLastErrorString 1576// from src/solaris/hpi/src/system_md.c 1577 1578size_t os::lasterror(char *buf, size_t len) { 1579 1580 if (errno == 0) return 0; 1581 1582 const char *s = ::strerror(errno); 1583 size_t n = ::strlen(s); 1584 if (n >= len) { 1585 n = len - 1; 1586 } 1587 ::strncpy(buf, s, n); 1588 buf[n] = '\0'; 1589 return n; 1590} 1591 1592intx os::current_thread_id() { return (intx)pthread_self(); } 1593int os::current_process_id() { 1594 1595 // Under the old linux thread library, linux gives each thread 1596 // its own process id. Because of this each thread will return 1597 // a different pid if this method were to return the result 1598 // of getpid(2). Linux provides no api that returns the pid 1599 // of the launcher thread for the vm. This implementation 1600 // returns a unique pid, the pid of the launcher thread 1601 // that starts the vm 'process'. 1602 1603 // Under the NPTL, getpid() returns the same pid as the 1604 // launcher thread rather than a unique pid per thread. 1605 // Use gettid() if you want the old pre NPTL behaviour. 1606 1607 // if you are looking for the result of a call to getpid() that 1608 // returns a unique pid for the calling thread, then look at the 1609 // OSThread::thread_id() method in osThread_linux.hpp file 1610 1611 return (int)(_initial_pid ? _initial_pid : getpid()); 1612} 1613 1614// DLL functions 1615 1616const char* os::dll_file_extension() { return ".so"; } 1617 1618// This must be hard coded because it's the system's temporary 1619// directory not the java application's temp directory, ala java.io.tmpdir. 1620const char* os::get_temp_directory() { return "/tmp"; } 1621 1622static bool file_exists(const char* filename) { 1623 struct stat statbuf; 1624 if (filename == NULL || strlen(filename) == 0) { 1625 return false; 1626 } 1627 return os::stat(filename, &statbuf) == 0; 1628} 1629 1630bool os::dll_build_name(char* buffer, size_t buflen, 1631 const char* pname, const char* fname) { 1632 bool retval = false; 1633 // Copied from libhpi 1634 const size_t pnamelen = pname ? strlen(pname) : 0; 1635 1636 // Return error on buffer overflow. 1637 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1638 return retval; 1639 } 1640 1641 if (pnamelen == 0) { 1642 snprintf(buffer, buflen, "lib%s.so", fname); 1643 retval = true; 1644 } else if (strchr(pname, *os::path_separator()) != NULL) { 1645 int n; 1646 char** pelements = split_path(pname, &n); 1647 for (int i = 0 ; i < n ; i++) { 1648 // Really shouldn't be NULL, but check can't hurt 1649 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1650 continue; // skip the empty path values 1651 } 1652 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1653 if (file_exists(buffer)) { 1654 retval = true; 1655 break; 1656 } 1657 } 1658 // release the storage 1659 for (int i = 0 ; i < n ; i++) { 1660 if (pelements[i] != NULL) { 1661 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal); 1662 } 1663 } 1664 if (pelements != NULL) { 1665 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal); 1666 } 1667 } else { 1668 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1669 retval = true; 1670 } 1671 return retval; 1672} 1673 1674const char* os::get_current_directory(char *buf, int buflen) { 1675 return getcwd(buf, buflen); 1676} 1677 1678// check if addr is inside libjvm.so 1679bool os::address_is_in_vm(address addr) { 1680 static address libjvm_base_addr; 1681 Dl_info dlinfo; 1682 1683 if (libjvm_base_addr == NULL) { 1684 dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo); 1685 libjvm_base_addr = (address)dlinfo.dli_fbase; 1686 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1687 } 1688 1689 if (dladdr((void *)addr, &dlinfo)) { 1690 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1691 } 1692 1693 return false; 1694} 1695 1696bool os::dll_address_to_function_name(address addr, char *buf, 1697 int buflen, int *offset) { 1698 Dl_info dlinfo; 1699 1700 if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) { 1701 if (buf != NULL) { 1702 if(!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1703 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1704 } 1705 } 1706 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1707 return true; 1708 } else if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != 0) { 1709 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1710 buf, buflen, offset, dlinfo.dli_fname)) { 1711 return true; 1712 } 1713 } 1714 1715 if (buf != NULL) buf[0] = '\0'; 1716 if (offset != NULL) *offset = -1; 1717 return false; 1718} 1719 1720struct _address_to_library_name { 1721 address addr; // input : memory address 1722 size_t buflen; // size of fname 1723 char* fname; // output: library name 1724 address base; // library base addr 1725}; 1726 1727static int address_to_library_name_callback(struct dl_phdr_info *info, 1728 size_t size, void *data) { 1729 int i; 1730 bool found = false; 1731 address libbase = NULL; 1732 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1733 1734 // iterate through all loadable segments 1735 for (i = 0; i < info->dlpi_phnum; i++) { 1736 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1737 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1738 // base address of a library is the lowest address of its loaded 1739 // segments. 1740 if (libbase == NULL || libbase > segbase) { 1741 libbase = segbase; 1742 } 1743 // see if 'addr' is within current segment 1744 if (segbase <= d->addr && 1745 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1746 found = true; 1747 } 1748 } 1749 } 1750 1751 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1752 // so dll_address_to_library_name() can fall through to use dladdr() which 1753 // can figure out executable name from argv[0]. 1754 if (found && info->dlpi_name && info->dlpi_name[0]) { 1755 d->base = libbase; 1756 if (d->fname) { 1757 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1758 } 1759 return 1; 1760 } 1761 return 0; 1762} 1763 1764bool os::dll_address_to_library_name(address addr, char* buf, 1765 int buflen, int* offset) { 1766 Dl_info dlinfo; 1767 struct _address_to_library_name data; 1768 1769 // There is a bug in old glibc dladdr() implementation that it could resolve 1770 // to wrong library name if the .so file has a base address != NULL. Here 1771 // we iterate through the program headers of all loaded libraries to find 1772 // out which library 'addr' really belongs to. This workaround can be 1773 // removed once the minimum requirement for glibc is moved to 2.3.x. 1774 data.addr = addr; 1775 data.fname = buf; 1776 data.buflen = buflen; 1777 data.base = NULL; 1778 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1779 1780 if (rslt) { 1781 // buf already contains library name 1782 if (offset) *offset = addr - data.base; 1783 return true; 1784 } else if (dladdr((void*)addr, &dlinfo)){ 1785 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1786 if (offset) *offset = addr - (address)dlinfo.dli_fbase; 1787 return true; 1788 } else { 1789 if (buf) buf[0] = '\0'; 1790 if (offset) *offset = -1; 1791 return false; 1792 } 1793} 1794 1795 // Loads .dll/.so and 1796 // in case of error it checks if .dll/.so was built for the 1797 // same architecture as Hotspot is running on 1798 1799void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1800{ 1801 void * result= ::dlopen(filename, RTLD_LAZY); 1802 if (result != NULL) { 1803 // Successful loading 1804 return result; 1805 } 1806 1807 Elf32_Ehdr elf_head; 1808 1809 // Read system error message into ebuf 1810 // It may or may not be overwritten below 1811 ::strncpy(ebuf, ::dlerror(), ebuflen-1); 1812 ebuf[ebuflen-1]='\0'; 1813 int diag_msg_max_length=ebuflen-strlen(ebuf); 1814 char* diag_msg_buf=ebuf+strlen(ebuf); 1815 1816 if (diag_msg_max_length==0) { 1817 // No more space in ebuf for additional diagnostics message 1818 return NULL; 1819 } 1820 1821 1822 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1823 1824 if (file_descriptor < 0) { 1825 // Can't open library, report dlerror() message 1826 return NULL; 1827 } 1828 1829 bool failed_to_read_elf_head= 1830 (sizeof(elf_head)!= 1831 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1832 1833 ::close(file_descriptor); 1834 if (failed_to_read_elf_head) { 1835 // file i/o error - report dlerror() msg 1836 return NULL; 1837 } 1838 1839 typedef struct { 1840 Elf32_Half code; // Actual value as defined in elf.h 1841 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1842 char elf_class; // 32 or 64 bit 1843 char endianess; // MSB or LSB 1844 char* name; // String representation 1845 } arch_t; 1846 1847 #ifndef EM_486 1848 #define EM_486 6 /* Intel 80486 */ 1849 #endif 1850 1851 static const arch_t arch_array[]={ 1852 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1853 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1854 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1855 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1856 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1857 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1858 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1859 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1860 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1861 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1862 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1863 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1864 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1865 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1866 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1867 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1868 }; 1869 1870 #if (defined IA32) 1871 static Elf32_Half running_arch_code=EM_386; 1872 #elif (defined AMD64) 1873 static Elf32_Half running_arch_code=EM_X86_64; 1874 #elif (defined IA64) 1875 static Elf32_Half running_arch_code=EM_IA_64; 1876 #elif (defined __sparc) && (defined _LP64) 1877 static Elf32_Half running_arch_code=EM_SPARCV9; 1878 #elif (defined __sparc) && (!defined _LP64) 1879 static Elf32_Half running_arch_code=EM_SPARC; 1880 #elif (defined __powerpc64__) 1881 static Elf32_Half running_arch_code=EM_PPC64; 1882 #elif (defined __powerpc__) 1883 static Elf32_Half running_arch_code=EM_PPC; 1884 #elif (defined ARM) 1885 static Elf32_Half running_arch_code=EM_ARM; 1886 #elif (defined S390) 1887 static Elf32_Half running_arch_code=EM_S390; 1888 #elif (defined ALPHA) 1889 static Elf32_Half running_arch_code=EM_ALPHA; 1890 #elif (defined MIPSEL) 1891 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1892 #elif (defined PARISC) 1893 static Elf32_Half running_arch_code=EM_PARISC; 1894 #elif (defined MIPS) 1895 static Elf32_Half running_arch_code=EM_MIPS; 1896 #elif (defined M68K) 1897 static Elf32_Half running_arch_code=EM_68K; 1898 #else 1899 #error Method os::dll_load requires that one of following is defined:\ 1900 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1901 #endif 1902 1903 // Identify compatability class for VM's architecture and library's architecture 1904 // Obtain string descriptions for architectures 1905 1906 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1907 int running_arch_index=-1; 1908 1909 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 1910 if (running_arch_code == arch_array[i].code) { 1911 running_arch_index = i; 1912 } 1913 if (lib_arch.code == arch_array[i].code) { 1914 lib_arch.compat_class = arch_array[i].compat_class; 1915 lib_arch.name = arch_array[i].name; 1916 } 1917 } 1918 1919 assert(running_arch_index != -1, 1920 "Didn't find running architecture code (running_arch_code) in arch_array"); 1921 if (running_arch_index == -1) { 1922 // Even though running architecture detection failed 1923 // we may still continue with reporting dlerror() message 1924 return NULL; 1925 } 1926 1927 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1928 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1929 return NULL; 1930 } 1931 1932#ifndef S390 1933 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 1934 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 1935 return NULL; 1936 } 1937#endif // !S390 1938 1939 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 1940 if ( lib_arch.name!=NULL ) { 1941 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1942 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 1943 lib_arch.name, arch_array[running_arch_index].name); 1944 } else { 1945 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1946 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 1947 lib_arch.code, 1948 arch_array[running_arch_index].name); 1949 } 1950 } 1951 1952 return NULL; 1953} 1954 1955/* 1956 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 1957 * chances are you might want to run the generated bits against glibc-2.0 1958 * libdl.so, so always use locking for any version of glibc. 1959 */ 1960void* os::dll_lookup(void* handle, const char* name) { 1961 pthread_mutex_lock(&dl_mutex); 1962 void* res = dlsym(handle, name); 1963 pthread_mutex_unlock(&dl_mutex); 1964 return res; 1965} 1966 1967 1968static bool _print_ascii_file(const char* filename, outputStream* st) { 1969 int fd = ::open(filename, O_RDONLY); 1970 if (fd == -1) { 1971 return false; 1972 } 1973 1974 char buf[32]; 1975 int bytes; 1976 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 1977 st->print_raw(buf, bytes); 1978 } 1979 1980 ::close(fd); 1981 1982 return true; 1983} 1984 1985void os::print_dll_info(outputStream *st) { 1986 st->print_cr("Dynamic libraries:"); 1987 1988 char fname[32]; 1989 pid_t pid = os::Linux::gettid(); 1990 1991 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 1992 1993 if (!_print_ascii_file(fname, st)) { 1994 st->print("Can not get library information for pid = %d\n", pid); 1995 } 1996} 1997 1998void os::print_os_info_brief(outputStream* st) { 1999 os::Linux::print_distro_info(st); 2000 2001 os::Posix::print_uname_info(st); 2002 2003 os::Linux::print_libversion_info(st); 2004 2005} 2006 2007void os::print_os_info(outputStream* st) { 2008 st->print("OS:"); 2009 2010 os::Linux::print_distro_info(st); 2011 2012 os::Posix::print_uname_info(st); 2013 2014 // Print warning if unsafe chroot environment detected 2015 if (unsafe_chroot_detected) { 2016 st->print("WARNING!! "); 2017 st->print_cr(unstable_chroot_error); 2018 } 2019 2020 os::Linux::print_libversion_info(st); 2021 2022 os::Posix::print_rlimit_info(st); 2023 2024 os::Posix::print_load_average(st); 2025 2026 os::Linux::print_full_memory_info(st); 2027} 2028 2029// Try to identify popular distros. 2030// Most Linux distributions have /etc/XXX-release file, which contains 2031// the OS version string. Some have more than one /etc/XXX-release file 2032// (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.), 2033// so the order is important. 2034void os::Linux::print_distro_info(outputStream* st) { 2035 if (!_print_ascii_file("/etc/mandrake-release", st) && 2036 !_print_ascii_file("/etc/sun-release", st) && 2037 !_print_ascii_file("/etc/redhat-release", st) && 2038 !_print_ascii_file("/etc/SuSE-release", st) && 2039 !_print_ascii_file("/etc/turbolinux-release", st) && 2040 !_print_ascii_file("/etc/gentoo-release", st) && 2041 !_print_ascii_file("/etc/debian_version", st) && 2042 !_print_ascii_file("/etc/ltib-release", st) && 2043 !_print_ascii_file("/etc/angstrom-version", st)) { 2044 st->print("Linux"); 2045 } 2046 st->cr(); 2047} 2048 2049void os::Linux::print_libversion_info(outputStream* st) { 2050 // libc, pthread 2051 st->print("libc:"); 2052 st->print(os::Linux::glibc_version()); st->print(" "); 2053 st->print(os::Linux::libpthread_version()); st->print(" "); 2054 if (os::Linux::is_LinuxThreads()) { 2055 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2056 } 2057 st->cr(); 2058} 2059 2060void os::Linux::print_full_memory_info(outputStream* st) { 2061 st->print("\n/proc/meminfo:\n"); 2062 _print_ascii_file("/proc/meminfo", st); 2063 st->cr(); 2064} 2065 2066void os::print_memory_info(outputStream* st) { 2067 2068 st->print("Memory:"); 2069 st->print(" %dk page", os::vm_page_size()>>10); 2070 2071 // values in struct sysinfo are "unsigned long" 2072 struct sysinfo si; 2073 sysinfo(&si); 2074 2075 st->print(", physical " UINT64_FORMAT "k", 2076 os::physical_memory() >> 10); 2077 st->print("(" UINT64_FORMAT "k free)", 2078 os::available_memory() >> 10); 2079 st->print(", swap " UINT64_FORMAT "k", 2080 ((jlong)si.totalswap * si.mem_unit) >> 10); 2081 st->print("(" UINT64_FORMAT "k free)", 2082 ((jlong)si.freeswap * si.mem_unit) >> 10); 2083 st->cr(); 2084} 2085 2086void os::pd_print_cpu_info(outputStream* st) { 2087 st->print("\n/proc/cpuinfo:\n"); 2088 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2089 st->print(" <Not Available>"); 2090 } 2091 st->cr(); 2092} 2093 2094// Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific 2095// but they're the same for all the linux arch that we support 2096// and they're the same for solaris but there's no common place to put this. 2097const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR", 2098 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG", 2099 "ILL_COPROC", "ILL_BADSTK" }; 2100 2101const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV", 2102 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES", 2103 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" }; 2104 2105const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" }; 2106 2107const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" }; 2108 2109void os::print_siginfo(outputStream* st, void* siginfo) { 2110 st->print("siginfo:"); 2111 2112 const int buflen = 100; 2113 char buf[buflen]; 2114 siginfo_t *si = (siginfo_t*)siginfo; 2115 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen)); 2116 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) { 2117 st->print("si_errno=%s", buf); 2118 } else { 2119 st->print("si_errno=%d", si->si_errno); 2120 } 2121 const int c = si->si_code; 2122 assert(c > 0, "unexpected si_code"); 2123 switch (si->si_signo) { 2124 case SIGILL: 2125 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]); 2126 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2127 break; 2128 case SIGFPE: 2129 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]); 2130 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2131 break; 2132 case SIGSEGV: 2133 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]); 2134 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2135 break; 2136 case SIGBUS: 2137 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]); 2138 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2139 break; 2140 default: 2141 st->print(", si_code=%d", si->si_code); 2142 // no si_addr 2143 } 2144 2145 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2146 UseSharedSpaces) { 2147 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2148 if (mapinfo->is_in_shared_space(si->si_addr)) { 2149 st->print("\n\nError accessing class data sharing archive." \ 2150 " Mapped file inaccessible during execution, " \ 2151 " possible disk/network problem."); 2152 } 2153 } 2154 st->cr(); 2155} 2156 2157 2158static void print_signal_handler(outputStream* st, int sig, 2159 char* buf, size_t buflen); 2160 2161void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2162 st->print_cr("Signal Handlers:"); 2163 print_signal_handler(st, SIGSEGV, buf, buflen); 2164 print_signal_handler(st, SIGBUS , buf, buflen); 2165 print_signal_handler(st, SIGFPE , buf, buflen); 2166 print_signal_handler(st, SIGPIPE, buf, buflen); 2167 print_signal_handler(st, SIGXFSZ, buf, buflen); 2168 print_signal_handler(st, SIGILL , buf, buflen); 2169 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2170 print_signal_handler(st, SR_signum, buf, buflen); 2171 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2172 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2173 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2174 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2175} 2176 2177static char saved_jvm_path[MAXPATHLEN] = {0}; 2178 2179// Find the full path to the current module, libjvm.so 2180void os::jvm_path(char *buf, jint buflen) { 2181 // Error checking. 2182 if (buflen < MAXPATHLEN) { 2183 assert(false, "must use a large-enough buffer"); 2184 buf[0] = '\0'; 2185 return; 2186 } 2187 // Lazy resolve the path to current module. 2188 if (saved_jvm_path[0] != 0) { 2189 strcpy(buf, saved_jvm_path); 2190 return; 2191 } 2192 2193 char dli_fname[MAXPATHLEN]; 2194 bool ret = dll_address_to_library_name( 2195 CAST_FROM_FN_PTR(address, os::jvm_path), 2196 dli_fname, sizeof(dli_fname), NULL); 2197 assert(ret != 0, "cannot locate libjvm"); 2198 char *rp = realpath(dli_fname, buf); 2199 if (rp == NULL) 2200 return; 2201 2202 if (Arguments::created_by_gamma_launcher()) { 2203 // Support for the gamma launcher. Typical value for buf is 2204 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at 2205 // the right place in the string, then assume we are installed in a JDK and 2206 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix 2207 // up the path so it looks like libjvm.so is installed there (append a 2208 // fake suffix hotspot/libjvm.so). 2209 const char *p = buf + strlen(buf) - 1; 2210 for (int count = 0; p > buf && count < 5; ++count) { 2211 for (--p; p > buf && *p != '/'; --p) 2212 /* empty */ ; 2213 } 2214 2215 if (strncmp(p, "/jre/lib/", 9) != 0) { 2216 // Look for JAVA_HOME in the environment. 2217 char* java_home_var = ::getenv("JAVA_HOME"); 2218 if (java_home_var != NULL && java_home_var[0] != 0) { 2219 char* jrelib_p; 2220 int len; 2221 2222 // Check the current module name "libjvm.so". 2223 p = strrchr(buf, '/'); 2224 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2225 2226 rp = realpath(java_home_var, buf); 2227 if (rp == NULL) 2228 return; 2229 2230 // determine if this is a legacy image or modules image 2231 // modules image doesn't have "jre" subdirectory 2232 len = strlen(buf); 2233 jrelib_p = buf + len; 2234 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2235 if (0 != access(buf, F_OK)) { 2236 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2237 } 2238 2239 if (0 == access(buf, F_OK)) { 2240 // Use current module name "libjvm.so" 2241 len = strlen(buf); 2242 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2243 } else { 2244 // Go back to path of .so 2245 rp = realpath(dli_fname, buf); 2246 if (rp == NULL) 2247 return; 2248 } 2249 } 2250 } 2251 } 2252 2253 strcpy(saved_jvm_path, buf); 2254} 2255 2256void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2257 // no prefix required, not even "_" 2258} 2259 2260void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2261 // no suffix required 2262} 2263 2264//////////////////////////////////////////////////////////////////////////////// 2265// sun.misc.Signal support 2266 2267static volatile jint sigint_count = 0; 2268 2269static void 2270UserHandler(int sig, void *siginfo, void *context) { 2271 // 4511530 - sem_post is serialized and handled by the manager thread. When 2272 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2273 // don't want to flood the manager thread with sem_post requests. 2274 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2275 return; 2276 2277 // Ctrl-C is pressed during error reporting, likely because the error 2278 // handler fails to abort. Let VM die immediately. 2279 if (sig == SIGINT && is_error_reported()) { 2280 os::die(); 2281 } 2282 2283 os::signal_notify(sig); 2284} 2285 2286void* os::user_handler() { 2287 return CAST_FROM_FN_PTR(void*, UserHandler); 2288} 2289 2290extern "C" { 2291 typedef void (*sa_handler_t)(int); 2292 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2293} 2294 2295void* os::signal(int signal_number, void* handler) { 2296 struct sigaction sigAct, oldSigAct; 2297 2298 sigfillset(&(sigAct.sa_mask)); 2299 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2300 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2301 2302 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2303 // -1 means registration failed 2304 return (void *)-1; 2305 } 2306 2307 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2308} 2309 2310void os::signal_raise(int signal_number) { 2311 ::raise(signal_number); 2312} 2313 2314/* 2315 * The following code is moved from os.cpp for making this 2316 * code platform specific, which it is by its very nature. 2317 */ 2318 2319// Will be modified when max signal is changed to be dynamic 2320int os::sigexitnum_pd() { 2321 return NSIG; 2322} 2323 2324// a counter for each possible signal value 2325static volatile jint pending_signals[NSIG+1] = { 0 }; 2326 2327// Linux(POSIX) specific hand shaking semaphore. 2328static sem_t sig_sem; 2329 2330void os::signal_init_pd() { 2331 // Initialize signal structures 2332 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2333 2334 // Initialize signal semaphore 2335 ::sem_init(&sig_sem, 0, 0); 2336} 2337 2338void os::signal_notify(int sig) { 2339 Atomic::inc(&pending_signals[sig]); 2340 ::sem_post(&sig_sem); 2341} 2342 2343static int check_pending_signals(bool wait) { 2344 Atomic::store(0, &sigint_count); 2345 for (;;) { 2346 for (int i = 0; i < NSIG + 1; i++) { 2347 jint n = pending_signals[i]; 2348 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2349 return i; 2350 } 2351 } 2352 if (!wait) { 2353 return -1; 2354 } 2355 JavaThread *thread = JavaThread::current(); 2356 ThreadBlockInVM tbivm(thread); 2357 2358 bool threadIsSuspended; 2359 do { 2360 thread->set_suspend_equivalent(); 2361 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2362 ::sem_wait(&sig_sem); 2363 2364 // were we externally suspended while we were waiting? 2365 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2366 if (threadIsSuspended) { 2367 // 2368 // The semaphore has been incremented, but while we were waiting 2369 // another thread suspended us. We don't want to continue running 2370 // while suspended because that would surprise the thread that 2371 // suspended us. 2372 // 2373 ::sem_post(&sig_sem); 2374 2375 thread->java_suspend_self(); 2376 } 2377 } while (threadIsSuspended); 2378 } 2379} 2380 2381int os::signal_lookup() { 2382 return check_pending_signals(false); 2383} 2384 2385int os::signal_wait() { 2386 return check_pending_signals(true); 2387} 2388 2389//////////////////////////////////////////////////////////////////////////////// 2390// Virtual Memory 2391 2392int os::vm_page_size() { 2393 // Seems redundant as all get out 2394 assert(os::Linux::page_size() != -1, "must call os::init"); 2395 return os::Linux::page_size(); 2396} 2397 2398// Solaris allocates memory by pages. 2399int os::vm_allocation_granularity() { 2400 assert(os::Linux::page_size() != -1, "must call os::init"); 2401 return os::Linux::page_size(); 2402} 2403 2404// Rationale behind this function: 2405// current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2406// mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2407// samples for JITted code. Here we create private executable mapping over the code cache 2408// and then we can use standard (well, almost, as mapping can change) way to provide 2409// info for the reporting script by storing timestamp and location of symbol 2410void linux_wrap_code(char* base, size_t size) { 2411 static volatile jint cnt = 0; 2412 2413 if (!UseOprofile) { 2414 return; 2415 } 2416 2417 char buf[PATH_MAX+1]; 2418 int num = Atomic::add(1, &cnt); 2419 2420 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2421 os::get_temp_directory(), os::current_process_id(), num); 2422 unlink(buf); 2423 2424 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2425 2426 if (fd != -1) { 2427 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2428 if (rv != (off_t)-1) { 2429 if (::write(fd, "", 1) == 1) { 2430 mmap(base, size, 2431 PROT_READ|PROT_WRITE|PROT_EXEC, 2432 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2433 } 2434 } 2435 ::close(fd); 2436 unlink(buf); 2437 } 2438} 2439 2440// NOTE: Linux kernel does not really reserve the pages for us. 2441// All it does is to check if there are enough free pages 2442// left at the time of mmap(). This could be a potential 2443// problem. 2444bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2445 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2446 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2447 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2448 if (res != (uintptr_t) MAP_FAILED) { 2449 if (UseNUMAInterleaving) { 2450 numa_make_global(addr, size); 2451 } 2452 return true; 2453 } 2454 return false; 2455} 2456 2457// Define MAP_HUGETLB here so we can build HotSpot on old systems. 2458#ifndef MAP_HUGETLB 2459#define MAP_HUGETLB 0x40000 2460#endif 2461 2462// Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2463#ifndef MADV_HUGEPAGE 2464#define MADV_HUGEPAGE 14 2465#endif 2466 2467bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2468 bool exec) { 2469 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) { 2470 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2471 uintptr_t res = 2472 (uintptr_t) ::mmap(addr, size, prot, 2473 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_HUGETLB, 2474 -1, 0); 2475 if (res != (uintptr_t) MAP_FAILED) { 2476 if (UseNUMAInterleaving) { 2477 numa_make_global(addr, size); 2478 } 2479 return true; 2480 } 2481 // Fall through and try to use small pages 2482 } 2483 2484 if (commit_memory(addr, size, exec)) { 2485 realign_memory(addr, size, alignment_hint); 2486 return true; 2487 } 2488 return false; 2489} 2490 2491void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2492 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) { 2493 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2494 // be supported or the memory may already be backed by huge pages. 2495 ::madvise(addr, bytes, MADV_HUGEPAGE); 2496 } 2497} 2498 2499void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2500 // This method works by doing an mmap over an existing mmaping and effectively discarding 2501 // the existing pages. However it won't work for SHM-based large pages that cannot be 2502 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2503 // small pages on top of the SHM segment. This method always works for small pages, so we 2504 // allow that in any case. 2505 if (alignment_hint <= (size_t)os::vm_page_size() || !UseSHM) { 2506 commit_memory(addr, bytes, alignment_hint, false); 2507 } 2508} 2509 2510void os::numa_make_global(char *addr, size_t bytes) { 2511 Linux::numa_interleave_memory(addr, bytes); 2512} 2513 2514void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2515 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2516} 2517 2518bool os::numa_topology_changed() { return false; } 2519 2520size_t os::numa_get_groups_num() { 2521 int max_node = Linux::numa_max_node(); 2522 return max_node > 0 ? max_node + 1 : 1; 2523} 2524 2525int os::numa_get_group_id() { 2526 int cpu_id = Linux::sched_getcpu(); 2527 if (cpu_id != -1) { 2528 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2529 if (lgrp_id != -1) { 2530 return lgrp_id; 2531 } 2532 } 2533 return 0; 2534} 2535 2536size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2537 for (size_t i = 0; i < size; i++) { 2538 ids[i] = i; 2539 } 2540 return size; 2541} 2542 2543bool os::get_page_info(char *start, page_info* info) { 2544 return false; 2545} 2546 2547char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2548 return end; 2549} 2550 2551 2552int os::Linux::sched_getcpu_syscall(void) { 2553 unsigned int cpu; 2554 int retval = -1; 2555 2556#if defined(IA32) 2557# ifndef SYS_getcpu 2558# define SYS_getcpu 318 2559# endif 2560 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2561#elif defined(AMD64) 2562// Unfortunately we have to bring all these macros here from vsyscall.h 2563// to be able to compile on old linuxes. 2564# define __NR_vgetcpu 2 2565# define VSYSCALL_START (-10UL << 20) 2566# define VSYSCALL_SIZE 1024 2567# define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2568 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2569 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2570 retval = vgetcpu(&cpu, NULL, NULL); 2571#endif 2572 2573 return (retval == -1) ? retval : cpu; 2574} 2575 2576// Something to do with the numa-aware allocator needs these symbols 2577extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2578extern "C" JNIEXPORT void numa_error(char *where) { } 2579extern "C" JNIEXPORT int fork1() { return fork(); } 2580 2581 2582// If we are running with libnuma version > 2, then we should 2583// be trying to use symbols with versions 1.1 2584// If we are running with earlier version, which did not have symbol versions, 2585// we should use the base version. 2586void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2587 void *f = dlvsym(handle, name, "libnuma_1.1"); 2588 if (f == NULL) { 2589 f = dlsym(handle, name); 2590 } 2591 return f; 2592} 2593 2594bool os::Linux::libnuma_init() { 2595 // sched_getcpu() should be in libc. 2596 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2597 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2598 2599 // If it's not, try a direct syscall. 2600 if (sched_getcpu() == -1) 2601 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall)); 2602 2603 if (sched_getcpu() != -1) { // Does it work? 2604 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2605 if (handle != NULL) { 2606 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2607 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2608 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2609 libnuma_dlsym(handle, "numa_max_node"))); 2610 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2611 libnuma_dlsym(handle, "numa_available"))); 2612 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2613 libnuma_dlsym(handle, "numa_tonode_memory"))); 2614 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2615 libnuma_dlsym(handle, "numa_interleave_memory"))); 2616 2617 2618 if (numa_available() != -1) { 2619 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2620 // Create a cpu -> node mapping 2621 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2622 rebuild_cpu_to_node_map(); 2623 return true; 2624 } 2625 } 2626 } 2627 return false; 2628} 2629 2630// rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2631// The table is later used in get_node_by_cpu(). 2632void os::Linux::rebuild_cpu_to_node_map() { 2633 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2634 // in libnuma (possible values are starting from 16, 2635 // and continuing up with every other power of 2, but less 2636 // than the maximum number of CPUs supported by kernel), and 2637 // is a subject to change (in libnuma version 2 the requirements 2638 // are more reasonable) we'll just hardcode the number they use 2639 // in the library. 2640 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2641 2642 size_t cpu_num = os::active_processor_count(); 2643 size_t cpu_map_size = NCPUS / BitsPerCLong; 2644 size_t cpu_map_valid_size = 2645 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2646 2647 cpu_to_node()->clear(); 2648 cpu_to_node()->at_grow(cpu_num - 1); 2649 size_t node_num = numa_get_groups_num(); 2650 2651 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2652 for (size_t i = 0; i < node_num; i++) { 2653 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2654 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2655 if (cpu_map[j] != 0) { 2656 for (size_t k = 0; k < BitsPerCLong; k++) { 2657 if (cpu_map[j] & (1UL << k)) { 2658 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2659 } 2660 } 2661 } 2662 } 2663 } 2664 } 2665 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal); 2666} 2667 2668int os::Linux::get_node_by_cpu(int cpu_id) { 2669 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2670 return cpu_to_node()->at(cpu_id); 2671 } 2672 return -1; 2673} 2674 2675GrowableArray<int>* os::Linux::_cpu_to_node; 2676os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2677os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2678os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2679os::Linux::numa_available_func_t os::Linux::_numa_available; 2680os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2681os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2682unsigned long* os::Linux::_numa_all_nodes; 2683 2684bool os::pd_uncommit_memory(char* addr, size_t size) { 2685 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2686 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2687 return res != (uintptr_t) MAP_FAILED; 2688} 2689 2690// Linux uses a growable mapping for the stack, and if the mapping for 2691// the stack guard pages is not removed when we detach a thread the 2692// stack cannot grow beyond the pages where the stack guard was 2693// mapped. If at some point later in the process the stack expands to 2694// that point, the Linux kernel cannot expand the stack any further 2695// because the guard pages are in the way, and a segfault occurs. 2696// 2697// However, it's essential not to split the stack region by unmapping 2698// a region (leaving a hole) that's already part of the stack mapping, 2699// so if the stack mapping has already grown beyond the guard pages at 2700// the time we create them, we have to truncate the stack mapping. 2701// So, we need to know the extent of the stack mapping when 2702// create_stack_guard_pages() is called. 2703 2704// Find the bounds of the stack mapping. Return true for success. 2705// 2706// We only need this for stacks that are growable: at the time of 2707// writing thread stacks don't use growable mappings (i.e. those 2708// creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 2709// only applies to the main thread. 2710 2711static 2712bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) { 2713 2714 char buf[128]; 2715 int fd, sz; 2716 2717 if ((fd = ::open("/proc/self/maps", O_RDONLY)) < 0) { 2718 return false; 2719 } 2720 2721 const char kw[] = "[stack]"; 2722 const int kwlen = sizeof(kw)-1; 2723 2724 // Address part of /proc/self/maps couldn't be more than 128 bytes 2725 while ((sz = os::get_line_chars(fd, buf, sizeof(buf))) > 0) { 2726 if (sz > kwlen && ::memcmp(buf+sz-kwlen, kw, kwlen) == 0) { 2727 // Extract addresses 2728 if (sscanf(buf, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) { 2729 uintptr_t sp = (uintptr_t) __builtin_frame_address(0); 2730 if (sp >= *bottom && sp <= *top) { 2731 ::close(fd); 2732 return true; 2733 } 2734 } 2735 } 2736 } 2737 2738 ::close(fd); 2739 return false; 2740} 2741 2742 2743// If the (growable) stack mapping already extends beyond the point 2744// where we're going to put our guard pages, truncate the mapping at 2745// that point by munmap()ping it. This ensures that when we later 2746// munmap() the guard pages we don't leave a hole in the stack 2747// mapping. This only affects the main/initial thread, but guard 2748// against future OS changes 2749bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 2750 uintptr_t stack_extent, stack_base; 2751 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true); 2752 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) { 2753 assert(os::Linux::is_initial_thread(), 2754 "growable stack in non-initial thread"); 2755 if (stack_extent < (uintptr_t)addr) 2756 ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent); 2757 } 2758 2759 return os::commit_memory(addr, size); 2760} 2761 2762// If this is a growable mapping, remove the guard pages entirely by 2763// munmap()ping them. If not, just call uncommit_memory(). This only 2764// affects the main/initial thread, but guard against future OS changes 2765bool os::remove_stack_guard_pages(char* addr, size_t size) { 2766 uintptr_t stack_extent, stack_base; 2767 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true); 2768 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) { 2769 assert(os::Linux::is_initial_thread(), 2770 "growable stack in non-initial thread"); 2771 2772 return ::munmap(addr, size) == 0; 2773 } 2774 2775 return os::uncommit_memory(addr, size); 2776} 2777 2778static address _highest_vm_reserved_address = NULL; 2779 2780// If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 2781// at 'requested_addr'. If there are existing memory mappings at the same 2782// location, however, they will be overwritten. If 'fixed' is false, 2783// 'requested_addr' is only treated as a hint, the return value may or 2784// may not start from the requested address. Unlike Linux mmap(), this 2785// function returns NULL to indicate failure. 2786static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 2787 char * addr; 2788 int flags; 2789 2790 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 2791 if (fixed) { 2792 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 2793 flags |= MAP_FIXED; 2794 } 2795 2796 // Map uncommitted pages PROT_READ and PROT_WRITE, change access 2797 // to PROT_EXEC if executable when we commit the page. 2798 addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE, 2799 flags, -1, 0); 2800 2801 if (addr != MAP_FAILED) { 2802 // anon_mmap() should only get called during VM initialization, 2803 // don't need lock (actually we can skip locking even it can be called 2804 // from multiple threads, because _highest_vm_reserved_address is just a 2805 // hint about the upper limit of non-stack memory regions.) 2806 if ((address)addr + bytes > _highest_vm_reserved_address) { 2807 _highest_vm_reserved_address = (address)addr + bytes; 2808 } 2809 } 2810 2811 return addr == MAP_FAILED ? NULL : addr; 2812} 2813 2814// Don't update _highest_vm_reserved_address, because there might be memory 2815// regions above addr + size. If so, releasing a memory region only creates 2816// a hole in the address space, it doesn't help prevent heap-stack collision. 2817// 2818static int anon_munmap(char * addr, size_t size) { 2819 return ::munmap(addr, size) == 0; 2820} 2821 2822char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 2823 size_t alignment_hint) { 2824 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 2825} 2826 2827bool os::pd_release_memory(char* addr, size_t size) { 2828 return anon_munmap(addr, size); 2829} 2830 2831static address highest_vm_reserved_address() { 2832 return _highest_vm_reserved_address; 2833} 2834 2835static bool linux_mprotect(char* addr, size_t size, int prot) { 2836 // Linux wants the mprotect address argument to be page aligned. 2837 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 2838 2839 // According to SUSv3, mprotect() should only be used with mappings 2840 // established by mmap(), and mmap() always maps whole pages. Unaligned 2841 // 'addr' likely indicates problem in the VM (e.g. trying to change 2842 // protection of malloc'ed or statically allocated memory). Check the 2843 // caller if you hit this assert. 2844 assert(addr == bottom, "sanity check"); 2845 2846 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 2847 return ::mprotect(bottom, size, prot) == 0; 2848} 2849 2850// Set protections specified 2851bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 2852 bool is_committed) { 2853 unsigned int p = 0; 2854 switch (prot) { 2855 case MEM_PROT_NONE: p = PROT_NONE; break; 2856 case MEM_PROT_READ: p = PROT_READ; break; 2857 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 2858 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 2859 default: 2860 ShouldNotReachHere(); 2861 } 2862 // is_committed is unused. 2863 return linux_mprotect(addr, bytes, p); 2864} 2865 2866bool os::guard_memory(char* addr, size_t size) { 2867 return linux_mprotect(addr, size, PROT_NONE); 2868} 2869 2870bool os::unguard_memory(char* addr, size_t size) { 2871 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 2872} 2873 2874bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 2875 bool result = false; 2876 void *p = mmap (NULL, page_size, PROT_READ|PROT_WRITE, 2877 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 2878 -1, 0); 2879 2880 if (p != (void *) -1) { 2881 // We don't know if this really is a huge page or not. 2882 FILE *fp = fopen("/proc/self/maps", "r"); 2883 if (fp) { 2884 while (!feof(fp)) { 2885 char chars[257]; 2886 long x = 0; 2887 if (fgets(chars, sizeof(chars), fp)) { 2888 if (sscanf(chars, "%lx-%*x", &x) == 1 2889 && x == (long)p) { 2890 if (strstr (chars, "hugepage")) { 2891 result = true; 2892 break; 2893 } 2894 } 2895 } 2896 } 2897 fclose(fp); 2898 } 2899 munmap (p, page_size); 2900 if (result) 2901 return true; 2902 } 2903 2904 if (warn) { 2905 warning("HugeTLBFS is not supported by the operating system."); 2906 } 2907 2908 return result; 2909} 2910 2911/* 2912* Set the coredump_filter bits to include largepages in core dump (bit 6) 2913* 2914* From the coredump_filter documentation: 2915* 2916* - (bit 0) anonymous private memory 2917* - (bit 1) anonymous shared memory 2918* - (bit 2) file-backed private memory 2919* - (bit 3) file-backed shared memory 2920* - (bit 4) ELF header pages in file-backed private memory areas (it is 2921* effective only if the bit 2 is cleared) 2922* - (bit 5) hugetlb private memory 2923* - (bit 6) hugetlb shared memory 2924*/ 2925static void set_coredump_filter(void) { 2926 FILE *f; 2927 long cdm; 2928 2929 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 2930 return; 2931 } 2932 2933 if (fscanf(f, "%lx", &cdm) != 1) { 2934 fclose(f); 2935 return; 2936 } 2937 2938 rewind(f); 2939 2940 if ((cdm & LARGEPAGES_BIT) == 0) { 2941 cdm |= LARGEPAGES_BIT; 2942 fprintf(f, "%#lx", cdm); 2943 } 2944 2945 fclose(f); 2946} 2947 2948// Large page support 2949 2950static size_t _large_page_size = 0; 2951 2952void os::large_page_init() { 2953 if (!UseLargePages) { 2954 UseHugeTLBFS = false; 2955 UseSHM = false; 2956 return; 2957 } 2958 2959 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && FLAG_IS_DEFAULT(UseSHM)) { 2960 // If UseLargePages is specified on the command line try both methods, 2961 // if it's default, then try only HugeTLBFS. 2962 if (FLAG_IS_DEFAULT(UseLargePages)) { 2963 UseHugeTLBFS = true; 2964 } else { 2965 UseHugeTLBFS = UseSHM = true; 2966 } 2967 } 2968 2969 if (LargePageSizeInBytes) { 2970 _large_page_size = LargePageSizeInBytes; 2971 } else { 2972 // large_page_size on Linux is used to round up heap size. x86 uses either 2973 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 2974 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 2975 // page as large as 256M. 2976 // 2977 // Here we try to figure out page size by parsing /proc/meminfo and looking 2978 // for a line with the following format: 2979 // Hugepagesize: 2048 kB 2980 // 2981 // If we can't determine the value (e.g. /proc is not mounted, or the text 2982 // format has been changed), we'll use the largest page size supported by 2983 // the processor. 2984 2985#ifndef ZERO 2986 _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 2987 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 2988#endif // ZERO 2989 2990 FILE *fp = fopen("/proc/meminfo", "r"); 2991 if (fp) { 2992 while (!feof(fp)) { 2993 int x = 0; 2994 char buf[16]; 2995 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 2996 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 2997 _large_page_size = x * K; 2998 break; 2999 } 3000 } else { 3001 // skip to next line 3002 for (;;) { 3003 int ch = fgetc(fp); 3004 if (ch == EOF || ch == (int)'\n') break; 3005 } 3006 } 3007 } 3008 fclose(fp); 3009 } 3010 } 3011 3012 // print a warning if any large page related flag is specified on command line 3013 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3014 3015 const size_t default_page_size = (size_t)Linux::page_size(); 3016 if (_large_page_size > default_page_size) { 3017 _page_sizes[0] = _large_page_size; 3018 _page_sizes[1] = default_page_size; 3019 _page_sizes[2] = 0; 3020 } 3021 UseHugeTLBFS = UseHugeTLBFS && 3022 Linux::hugetlbfs_sanity_check(warn_on_failure, _large_page_size); 3023 3024 if (UseHugeTLBFS) 3025 UseSHM = false; 3026 3027 UseLargePages = UseHugeTLBFS || UseSHM; 3028 3029 set_coredump_filter(); 3030} 3031 3032#ifndef SHM_HUGETLB 3033#define SHM_HUGETLB 04000 3034#endif 3035 3036char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) { 3037 // "exec" is passed in but not used. Creating the shared image for 3038 // the code cache doesn't have an SHM_X executable permission to check. 3039 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3040 3041 key_t key = IPC_PRIVATE; 3042 char *addr; 3043 3044 bool warn_on_failure = UseLargePages && 3045 (!FLAG_IS_DEFAULT(UseLargePages) || 3046 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 3047 ); 3048 char msg[128]; 3049 3050 // Create a large shared memory region to attach to based on size. 3051 // Currently, size is the total size of the heap 3052 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3053 if (shmid == -1) { 3054 // Possible reasons for shmget failure: 3055 // 1. shmmax is too small for Java heap. 3056 // > check shmmax value: cat /proc/sys/kernel/shmmax 3057 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3058 // 2. not enough large page memory. 3059 // > check available large pages: cat /proc/meminfo 3060 // > increase amount of large pages: 3061 // echo new_value > /proc/sys/vm/nr_hugepages 3062 // Note 1: different Linux may use different name for this property, 3063 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3064 // Note 2: it's possible there's enough physical memory available but 3065 // they are so fragmented after a long run that they can't 3066 // coalesce into large pages. Try to reserve large pages when 3067 // the system is still "fresh". 3068 if (warn_on_failure) { 3069 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3070 warning(msg); 3071 } 3072 return NULL; 3073 } 3074 3075 // attach to the region 3076 addr = (char*)shmat(shmid, req_addr, 0); 3077 int err = errno; 3078 3079 // Remove shmid. If shmat() is successful, the actual shared memory segment 3080 // will be deleted when it's detached by shmdt() or when the process 3081 // terminates. If shmat() is not successful this will remove the shared 3082 // segment immediately. 3083 shmctl(shmid, IPC_RMID, NULL); 3084 3085 if ((intptr_t)addr == -1) { 3086 if (warn_on_failure) { 3087 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3088 warning(msg); 3089 } 3090 return NULL; 3091 } 3092 3093 if ((addr != NULL) && UseNUMAInterleaving) { 3094 numa_make_global(addr, bytes); 3095 } 3096 3097 return addr; 3098} 3099 3100bool os::release_memory_special(char* base, size_t bytes) { 3101 // detaching the SHM segment will also delete it, see reserve_memory_special() 3102 int rslt = shmdt(base); 3103 return rslt == 0; 3104} 3105 3106size_t os::large_page_size() { 3107 return _large_page_size; 3108} 3109 3110// HugeTLBFS allows application to commit large page memory on demand; 3111// with SysV SHM the entire memory region must be allocated as shared 3112// memory. 3113bool os::can_commit_large_page_memory() { 3114 return UseHugeTLBFS; 3115} 3116 3117bool os::can_execute_large_page_memory() { 3118 return UseHugeTLBFS; 3119} 3120 3121// Reserve memory at an arbitrary address, only if that area is 3122// available (and not reserved for something else). 3123 3124char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3125 const int max_tries = 10; 3126 char* base[max_tries]; 3127 size_t size[max_tries]; 3128 const size_t gap = 0x000000; 3129 3130 // Assert only that the size is a multiple of the page size, since 3131 // that's all that mmap requires, and since that's all we really know 3132 // about at this low abstraction level. If we need higher alignment, 3133 // we can either pass an alignment to this method or verify alignment 3134 // in one of the methods further up the call chain. See bug 5044738. 3135 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3136 3137 // Repeatedly allocate blocks until the block is allocated at the 3138 // right spot. Give up after max_tries. Note that reserve_memory() will 3139 // automatically update _highest_vm_reserved_address if the call is 3140 // successful. The variable tracks the highest memory address every reserved 3141 // by JVM. It is used to detect heap-stack collision if running with 3142 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3143 // space than needed, it could confuse the collision detecting code. To 3144 // solve the problem, save current _highest_vm_reserved_address and 3145 // calculate the correct value before return. 3146 address old_highest = _highest_vm_reserved_address; 3147 3148 // Linux mmap allows caller to pass an address as hint; give it a try first, 3149 // if kernel honors the hint then we can return immediately. 3150 char * addr = anon_mmap(requested_addr, bytes, false); 3151 if (addr == requested_addr) { 3152 return requested_addr; 3153 } 3154 3155 if (addr != NULL) { 3156 // mmap() is successful but it fails to reserve at the requested address 3157 anon_munmap(addr, bytes); 3158 } 3159 3160 int i; 3161 for (i = 0; i < max_tries; ++i) { 3162 base[i] = reserve_memory(bytes); 3163 3164 if (base[i] != NULL) { 3165 // Is this the block we wanted? 3166 if (base[i] == requested_addr) { 3167 size[i] = bytes; 3168 break; 3169 } 3170 3171 // Does this overlap the block we wanted? Give back the overlapped 3172 // parts and try again. 3173 3174 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3175 if (top_overlap >= 0 && top_overlap < bytes) { 3176 unmap_memory(base[i], top_overlap); 3177 base[i] += top_overlap; 3178 size[i] = bytes - top_overlap; 3179 } else { 3180 size_t bottom_overlap = base[i] + bytes - requested_addr; 3181 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3182 unmap_memory(requested_addr, bottom_overlap); 3183 size[i] = bytes - bottom_overlap; 3184 } else { 3185 size[i] = bytes; 3186 } 3187 } 3188 } 3189 } 3190 3191 // Give back the unused reserved pieces. 3192 3193 for (int j = 0; j < i; ++j) { 3194 if (base[j] != NULL) { 3195 unmap_memory(base[j], size[j]); 3196 } 3197 } 3198 3199 if (i < max_tries) { 3200 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3201 return requested_addr; 3202 } else { 3203 _highest_vm_reserved_address = old_highest; 3204 return NULL; 3205 } 3206} 3207 3208size_t os::read(int fd, void *buf, unsigned int nBytes) { 3209 return ::read(fd, buf, nBytes); 3210} 3211 3212// TODO-FIXME: reconcile Solaris' os::sleep with the linux variation. 3213// Solaris uses poll(), linux uses park(). 3214// Poll() is likely a better choice, assuming that Thread.interrupt() 3215// generates a SIGUSRx signal. Note that SIGUSR1 can interfere with 3216// SIGSEGV, see 4355769. 3217 3218int os::sleep(Thread* thread, jlong millis, bool interruptible) { 3219 assert(thread == Thread::current(), "thread consistency check"); 3220 3221 ParkEvent * const slp = thread->_SleepEvent ; 3222 slp->reset() ; 3223 OrderAccess::fence() ; 3224 3225 if (interruptible) { 3226 jlong prevtime = javaTimeNanos(); 3227 3228 for (;;) { 3229 if (os::is_interrupted(thread, true)) { 3230 return OS_INTRPT; 3231 } 3232 3233 jlong newtime = javaTimeNanos(); 3234 3235 if (newtime - prevtime < 0) { 3236 // time moving backwards, should only happen if no monotonic clock 3237 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3238 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3239 } else { 3240 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3241 } 3242 3243 if(millis <= 0) { 3244 return OS_OK; 3245 } 3246 3247 prevtime = newtime; 3248 3249 { 3250 assert(thread->is_Java_thread(), "sanity check"); 3251 JavaThread *jt = (JavaThread *) thread; 3252 ThreadBlockInVM tbivm(jt); 3253 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */); 3254 3255 jt->set_suspend_equivalent(); 3256 // cleared by handle_special_suspend_equivalent_condition() or 3257 // java_suspend_self() via check_and_wait_while_suspended() 3258 3259 slp->park(millis); 3260 3261 // were we externally suspended while we were waiting? 3262 jt->check_and_wait_while_suspended(); 3263 } 3264 } 3265 } else { 3266 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 3267 jlong prevtime = javaTimeNanos(); 3268 3269 for (;;) { 3270 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on 3271 // the 1st iteration ... 3272 jlong newtime = javaTimeNanos(); 3273 3274 if (newtime - prevtime < 0) { 3275 // time moving backwards, should only happen if no monotonic clock 3276 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3277 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3278 } else { 3279 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3280 } 3281 3282 if(millis <= 0) break ; 3283 3284 prevtime = newtime; 3285 slp->park(millis); 3286 } 3287 return OS_OK ; 3288 } 3289} 3290 3291int os::naked_sleep() { 3292 // %% make the sleep time an integer flag. for now use 1 millisec. 3293 return os::sleep(Thread::current(), 1, false); 3294} 3295 3296// Sleep forever; naked call to OS-specific sleep; use with CAUTION 3297void os::infinite_sleep() { 3298 while (true) { // sleep forever ... 3299 ::sleep(100); // ... 100 seconds at a time 3300 } 3301} 3302 3303// Used to convert frequent JVM_Yield() to nops 3304bool os::dont_yield() { 3305 return DontYieldALot; 3306} 3307 3308void os::yield() { 3309 sched_yield(); 3310} 3311 3312os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 3313 3314void os::yield_all(int attempts) { 3315 // Yields to all threads, including threads with lower priorities 3316 // Threads on Linux are all with same priority. The Solaris style 3317 // os::yield_all() with nanosleep(1ms) is not necessary. 3318 sched_yield(); 3319} 3320 3321// Called from the tight loops to possibly influence time-sharing heuristics 3322void os::loop_breaker(int attempts) { 3323 os::yield_all(attempts); 3324} 3325 3326//////////////////////////////////////////////////////////////////////////////// 3327// thread priority support 3328 3329// Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3330// only supports dynamic priority, static priority must be zero. For real-time 3331// applications, Linux supports SCHED_RR which allows static priority (1-99). 3332// However, for large multi-threaded applications, SCHED_RR is not only slower 3333// than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3334// of 5 runs - Sep 2005). 3335// 3336// The following code actually changes the niceness of kernel-thread/LWP. It 3337// has an assumption that setpriority() only modifies one kernel-thread/LWP, 3338// not the entire user process, and user level threads are 1:1 mapped to kernel 3339// threads. It has always been the case, but could change in the future. For 3340// this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3341// It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3342 3343int os::java_to_os_priority[CriticalPriority + 1] = { 3344 19, // 0 Entry should never be used 3345 3346 4, // 1 MinPriority 3347 3, // 2 3348 2, // 3 3349 3350 1, // 4 3351 0, // 5 NormPriority 3352 -1, // 6 3353 3354 -2, // 7 3355 -3, // 8 3356 -4, // 9 NearMaxPriority 3357 3358 -5, // 10 MaxPriority 3359 3360 -5 // 11 CriticalPriority 3361}; 3362 3363static int prio_init() { 3364 if (ThreadPriorityPolicy == 1) { 3365 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3366 // if effective uid is not root. Perhaps, a more elegant way of doing 3367 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3368 if (geteuid() != 0) { 3369 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3370 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3371 } 3372 ThreadPriorityPolicy = 0; 3373 } 3374 } 3375 if (UseCriticalJavaThreadPriority) { 3376 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3377 } 3378 return 0; 3379} 3380 3381OSReturn os::set_native_priority(Thread* thread, int newpri) { 3382 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 3383 3384 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3385 return (ret == 0) ? OS_OK : OS_ERR; 3386} 3387 3388OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3389 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3390 *priority_ptr = java_to_os_priority[NormPriority]; 3391 return OS_OK; 3392 } 3393 3394 errno = 0; 3395 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3396 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3397} 3398 3399// Hint to the underlying OS that a task switch would not be good. 3400// Void return because it's a hint and can fail. 3401void os::hint_no_preempt() {} 3402 3403//////////////////////////////////////////////////////////////////////////////// 3404// suspend/resume support 3405 3406// the low-level signal-based suspend/resume support is a remnant from the 3407// old VM-suspension that used to be for java-suspension, safepoints etc, 3408// within hotspot. Now there is a single use-case for this: 3409// - calling get_thread_pc() on the VMThread by the flat-profiler task 3410// that runs in the watcher thread. 3411// The remaining code is greatly simplified from the more general suspension 3412// code that used to be used. 3413// 3414// The protocol is quite simple: 3415// - suspend: 3416// - sends a signal to the target thread 3417// - polls the suspend state of the osthread using a yield loop 3418// - target thread signal handler (SR_handler) sets suspend state 3419// and blocks in sigsuspend until continued 3420// - resume: 3421// - sets target osthread state to continue 3422// - sends signal to end the sigsuspend loop in the SR_handler 3423// 3424// Note that the SR_lock plays no role in this suspend/resume protocol. 3425// 3426 3427static void resume_clear_context(OSThread *osthread) { 3428 osthread->set_ucontext(NULL); 3429 osthread->set_siginfo(NULL); 3430 3431 // notify the suspend action is completed, we have now resumed 3432 osthread->sr.clear_suspended(); 3433} 3434 3435static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 3436 osthread->set_ucontext(context); 3437 osthread->set_siginfo(siginfo); 3438} 3439 3440// 3441// Handler function invoked when a thread's execution is suspended or 3442// resumed. We have to be careful that only async-safe functions are 3443// called here (Note: most pthread functions are not async safe and 3444// should be avoided.) 3445// 3446// Note: sigwait() is a more natural fit than sigsuspend() from an 3447// interface point of view, but sigwait() prevents the signal hander 3448// from being run. libpthread would get very confused by not having 3449// its signal handlers run and prevents sigwait()'s use with the 3450// mutex granting granting signal. 3451// 3452// Currently only ever called on the VMThread 3453// 3454static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3455 // Save and restore errno to avoid confusing native code with EINTR 3456 // after sigsuspend. 3457 int old_errno = errno; 3458 3459 Thread* thread = Thread::current(); 3460 OSThread* osthread = thread->osthread(); 3461 assert(thread->is_VM_thread(), "Must be VMThread"); 3462 // read current suspend action 3463 int action = osthread->sr.suspend_action(); 3464 if (action == SR_SUSPEND) { 3465 suspend_save_context(osthread, siginfo, context); 3466 3467 // Notify the suspend action is about to be completed. do_suspend() 3468 // waits until SR_SUSPENDED is set and then returns. We will wait 3469 // here for a resume signal and that completes the suspend-other 3470 // action. do_suspend/do_resume is always called as a pair from 3471 // the same thread - so there are no races 3472 3473 // notify the caller 3474 osthread->sr.set_suspended(); 3475 3476 sigset_t suspend_set; // signals for sigsuspend() 3477 3478 // get current set of blocked signals and unblock resume signal 3479 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3480 sigdelset(&suspend_set, SR_signum); 3481 3482 // wait here until we are resumed 3483 do { 3484 sigsuspend(&suspend_set); 3485 // ignore all returns until we get a resume signal 3486 } while (osthread->sr.suspend_action() != SR_CONTINUE); 3487 3488 resume_clear_context(osthread); 3489 3490 } else { 3491 assert(action == SR_CONTINUE, "unexpected sr action"); 3492 // nothing special to do - just leave the handler 3493 } 3494 3495 errno = old_errno; 3496} 3497 3498 3499static int SR_initialize() { 3500 struct sigaction act; 3501 char *s; 3502 /* Get signal number to use for suspend/resume */ 3503 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 3504 int sig = ::strtol(s, 0, 10); 3505 if (sig > 0 || sig < _NSIG) { 3506 SR_signum = sig; 3507 } 3508 } 3509 3510 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 3511 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 3512 3513 sigemptyset(&SR_sigset); 3514 sigaddset(&SR_sigset, SR_signum); 3515 3516 /* Set up signal handler for suspend/resume */ 3517 act.sa_flags = SA_RESTART|SA_SIGINFO; 3518 act.sa_handler = (void (*)(int)) SR_handler; 3519 3520 // SR_signum is blocked by default. 3521 // 4528190 - We also need to block pthread restart signal (32 on all 3522 // supported Linux platforms). Note that LinuxThreads need to block 3523 // this signal for all threads to work properly. So we don't have 3524 // to use hard-coded signal number when setting up the mask. 3525 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 3526 3527 if (sigaction(SR_signum, &act, 0) == -1) { 3528 return -1; 3529 } 3530 3531 // Save signal flag 3532 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 3533 return 0; 3534} 3535 3536static int SR_finalize() { 3537 return 0; 3538} 3539 3540 3541// returns true on success and false on error - really an error is fatal 3542// but this seems the normal response to library errors 3543static bool do_suspend(OSThread* osthread) { 3544 // mark as suspended and send signal 3545 osthread->sr.set_suspend_action(SR_SUSPEND); 3546 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3547 assert_status(status == 0, status, "pthread_kill"); 3548 3549 // check status and wait until notified of suspension 3550 if (status == 0) { 3551 for (int i = 0; !osthread->sr.is_suspended(); i++) { 3552 os::yield_all(i); 3553 } 3554 osthread->sr.set_suspend_action(SR_NONE); 3555 return true; 3556 } 3557 else { 3558 osthread->sr.set_suspend_action(SR_NONE); 3559 return false; 3560 } 3561} 3562 3563static void do_resume(OSThread* osthread) { 3564 assert(osthread->sr.is_suspended(), "thread should be suspended"); 3565 osthread->sr.set_suspend_action(SR_CONTINUE); 3566 3567 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3568 assert_status(status == 0, status, "pthread_kill"); 3569 // check status and wait unit notified of resumption 3570 if (status == 0) { 3571 for (int i = 0; osthread->sr.is_suspended(); i++) { 3572 os::yield_all(i); 3573 } 3574 } 3575 osthread->sr.set_suspend_action(SR_NONE); 3576} 3577 3578//////////////////////////////////////////////////////////////////////////////// 3579// interrupt support 3580 3581void os::interrupt(Thread* thread) { 3582 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3583 "possibility of dangling Thread pointer"); 3584 3585 OSThread* osthread = thread->osthread(); 3586 3587 if (!osthread->interrupted()) { 3588 osthread->set_interrupted(true); 3589 // More than one thread can get here with the same value of osthread, 3590 // resulting in multiple notifications. We do, however, want the store 3591 // to interrupted() to be visible to other threads before we execute unpark(). 3592 OrderAccess::fence(); 3593 ParkEvent * const slp = thread->_SleepEvent ; 3594 if (slp != NULL) slp->unpark() ; 3595 } 3596 3597 // For JSR166. Unpark even if interrupt status already was set 3598 if (thread->is_Java_thread()) 3599 ((JavaThread*)thread)->parker()->unpark(); 3600 3601 ParkEvent * ev = thread->_ParkEvent ; 3602 if (ev != NULL) ev->unpark() ; 3603 3604} 3605 3606bool os::is_interrupted(Thread* thread, bool clear_interrupted) { 3607 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3608 "possibility of dangling Thread pointer"); 3609 3610 OSThread* osthread = thread->osthread(); 3611 3612 bool interrupted = osthread->interrupted(); 3613 3614 if (interrupted && clear_interrupted) { 3615 osthread->set_interrupted(false); 3616 // consider thread->_SleepEvent->reset() ... optional optimization 3617 } 3618 3619 return interrupted; 3620} 3621 3622/////////////////////////////////////////////////////////////////////////////////// 3623// signal handling (except suspend/resume) 3624 3625// This routine may be used by user applications as a "hook" to catch signals. 3626// The user-defined signal handler must pass unrecognized signals to this 3627// routine, and if it returns true (non-zero), then the signal handler must 3628// return immediately. If the flag "abort_if_unrecognized" is true, then this 3629// routine will never retun false (zero), but instead will execute a VM panic 3630// routine kill the process. 3631// 3632// If this routine returns false, it is OK to call it again. This allows 3633// the user-defined signal handler to perform checks either before or after 3634// the VM performs its own checks. Naturally, the user code would be making 3635// a serious error if it tried to handle an exception (such as a null check 3636// or breakpoint) that the VM was generating for its own correct operation. 3637// 3638// This routine may recognize any of the following kinds of signals: 3639// SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 3640// It should be consulted by handlers for any of those signals. 3641// 3642// The caller of this routine must pass in the three arguments supplied 3643// to the function referred to in the "sa_sigaction" (not the "sa_handler") 3644// field of the structure passed to sigaction(). This routine assumes that 3645// the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 3646// 3647// Note that the VM will print warnings if it detects conflicting signal 3648// handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 3649// 3650extern "C" JNIEXPORT int 3651JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 3652 void* ucontext, int abort_if_unrecognized); 3653 3654void signalHandler(int sig, siginfo_t* info, void* uc) { 3655 assert(info != NULL && uc != NULL, "it must be old kernel"); 3656 JVM_handle_linux_signal(sig, info, uc, true); 3657} 3658 3659 3660// This boolean allows users to forward their own non-matching signals 3661// to JVM_handle_linux_signal, harmlessly. 3662bool os::Linux::signal_handlers_are_installed = false; 3663 3664// For signal-chaining 3665struct sigaction os::Linux::sigact[MAXSIGNUM]; 3666unsigned int os::Linux::sigs = 0; 3667bool os::Linux::libjsig_is_loaded = false; 3668typedef struct sigaction *(*get_signal_t)(int); 3669get_signal_t os::Linux::get_signal_action = NULL; 3670 3671struct sigaction* os::Linux::get_chained_signal_action(int sig) { 3672 struct sigaction *actp = NULL; 3673 3674 if (libjsig_is_loaded) { 3675 // Retrieve the old signal handler from libjsig 3676 actp = (*get_signal_action)(sig); 3677 } 3678 if (actp == NULL) { 3679 // Retrieve the preinstalled signal handler from jvm 3680 actp = get_preinstalled_handler(sig); 3681 } 3682 3683 return actp; 3684} 3685 3686static bool call_chained_handler(struct sigaction *actp, int sig, 3687 siginfo_t *siginfo, void *context) { 3688 // Call the old signal handler 3689 if (actp->sa_handler == SIG_DFL) { 3690 // It's more reasonable to let jvm treat it as an unexpected exception 3691 // instead of taking the default action. 3692 return false; 3693 } else if (actp->sa_handler != SIG_IGN) { 3694 if ((actp->sa_flags & SA_NODEFER) == 0) { 3695 // automaticlly block the signal 3696 sigaddset(&(actp->sa_mask), sig); 3697 } 3698 3699 sa_handler_t hand; 3700 sa_sigaction_t sa; 3701 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 3702 // retrieve the chained handler 3703 if (siginfo_flag_set) { 3704 sa = actp->sa_sigaction; 3705 } else { 3706 hand = actp->sa_handler; 3707 } 3708 3709 if ((actp->sa_flags & SA_RESETHAND) != 0) { 3710 actp->sa_handler = SIG_DFL; 3711 } 3712 3713 // try to honor the signal mask 3714 sigset_t oset; 3715 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 3716 3717 // call into the chained handler 3718 if (siginfo_flag_set) { 3719 (*sa)(sig, siginfo, context); 3720 } else { 3721 (*hand)(sig); 3722 } 3723 3724 // restore the signal mask 3725 pthread_sigmask(SIG_SETMASK, &oset, 0); 3726 } 3727 // Tell jvm's signal handler the signal is taken care of. 3728 return true; 3729} 3730 3731bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 3732 bool chained = false; 3733 // signal-chaining 3734 if (UseSignalChaining) { 3735 struct sigaction *actp = get_chained_signal_action(sig); 3736 if (actp != NULL) { 3737 chained = call_chained_handler(actp, sig, siginfo, context); 3738 } 3739 } 3740 return chained; 3741} 3742 3743struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 3744 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 3745 return &sigact[sig]; 3746 } 3747 return NULL; 3748} 3749 3750void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 3751 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3752 sigact[sig] = oldAct; 3753 sigs |= (unsigned int)1 << sig; 3754} 3755 3756// for diagnostic 3757int os::Linux::sigflags[MAXSIGNUM]; 3758 3759int os::Linux::get_our_sigflags(int sig) { 3760 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3761 return sigflags[sig]; 3762} 3763 3764void os::Linux::set_our_sigflags(int sig, int flags) { 3765 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3766 sigflags[sig] = flags; 3767} 3768 3769void os::Linux::set_signal_handler(int sig, bool set_installed) { 3770 // Check for overwrite. 3771 struct sigaction oldAct; 3772 sigaction(sig, (struct sigaction*)NULL, &oldAct); 3773 3774 void* oldhand = oldAct.sa_sigaction 3775 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3776 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3777 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 3778 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 3779 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 3780 if (AllowUserSignalHandlers || !set_installed) { 3781 // Do not overwrite; user takes responsibility to forward to us. 3782 return; 3783 } else if (UseSignalChaining) { 3784 // save the old handler in jvm 3785 save_preinstalled_handler(sig, oldAct); 3786 // libjsig also interposes the sigaction() call below and saves the 3787 // old sigaction on it own. 3788 } else { 3789 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 3790 "%#lx for signal %d.", (long)oldhand, sig)); 3791 } 3792 } 3793 3794 struct sigaction sigAct; 3795 sigfillset(&(sigAct.sa_mask)); 3796 sigAct.sa_handler = SIG_DFL; 3797 if (!set_installed) { 3798 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3799 } else { 3800 sigAct.sa_sigaction = signalHandler; 3801 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3802 } 3803 // Save flags, which are set by ours 3804 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3805 sigflags[sig] = sigAct.sa_flags; 3806 3807 int ret = sigaction(sig, &sigAct, &oldAct); 3808 assert(ret == 0, "check"); 3809 3810 void* oldhand2 = oldAct.sa_sigaction 3811 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3812 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3813 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 3814} 3815 3816// install signal handlers for signals that HotSpot needs to 3817// handle in order to support Java-level exception handling. 3818 3819void os::Linux::install_signal_handlers() { 3820 if (!signal_handlers_are_installed) { 3821 signal_handlers_are_installed = true; 3822 3823 // signal-chaining 3824 typedef void (*signal_setting_t)(); 3825 signal_setting_t begin_signal_setting = NULL; 3826 signal_setting_t end_signal_setting = NULL; 3827 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3828 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 3829 if (begin_signal_setting != NULL) { 3830 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3831 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 3832 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 3833 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 3834 libjsig_is_loaded = true; 3835 assert(UseSignalChaining, "should enable signal-chaining"); 3836 } 3837 if (libjsig_is_loaded) { 3838 // Tell libjsig jvm is setting signal handlers 3839 (*begin_signal_setting)(); 3840 } 3841 3842 set_signal_handler(SIGSEGV, true); 3843 set_signal_handler(SIGPIPE, true); 3844 set_signal_handler(SIGBUS, true); 3845 set_signal_handler(SIGILL, true); 3846 set_signal_handler(SIGFPE, true); 3847 set_signal_handler(SIGXFSZ, true); 3848 3849 if (libjsig_is_loaded) { 3850 // Tell libjsig jvm finishes setting signal handlers 3851 (*end_signal_setting)(); 3852 } 3853 3854 // We don't activate signal checker if libjsig is in place, we trust ourselves 3855 // and if UserSignalHandler is installed all bets are off. 3856 // Log that signal checking is off only if -verbose:jni is specified. 3857 if (CheckJNICalls) { 3858 if (libjsig_is_loaded) { 3859 if (PrintJNIResolving) { 3860 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 3861 } 3862 check_signals = false; 3863 } 3864 if (AllowUserSignalHandlers) { 3865 if (PrintJNIResolving) { 3866 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 3867 } 3868 check_signals = false; 3869 } 3870 } 3871 } 3872} 3873 3874// This is the fastest way to get thread cpu time on Linux. 3875// Returns cpu time (user+sys) for any thread, not only for current. 3876// POSIX compliant clocks are implemented in the kernels 2.6.16+. 3877// It might work on 2.6.10+ with a special kernel/glibc patch. 3878// For reference, please, see IEEE Std 1003.1-2004: 3879// http://www.unix.org/single_unix_specification 3880 3881jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 3882 struct timespec tp; 3883 int rc = os::Linux::clock_gettime(clockid, &tp); 3884 assert(rc == 0, "clock_gettime is expected to return 0 code"); 3885 3886 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 3887} 3888 3889///// 3890// glibc on Linux platform uses non-documented flag 3891// to indicate, that some special sort of signal 3892// trampoline is used. 3893// We will never set this flag, and we should 3894// ignore this flag in our diagnostic 3895#ifdef SIGNIFICANT_SIGNAL_MASK 3896#undef SIGNIFICANT_SIGNAL_MASK 3897#endif 3898#define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 3899 3900static const char* get_signal_handler_name(address handler, 3901 char* buf, int buflen) { 3902 int offset; 3903 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 3904 if (found) { 3905 // skip directory names 3906 const char *p1, *p2; 3907 p1 = buf; 3908 size_t len = strlen(os::file_separator()); 3909 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 3910 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 3911 } else { 3912 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 3913 } 3914 return buf; 3915} 3916 3917static void print_signal_handler(outputStream* st, int sig, 3918 char* buf, size_t buflen) { 3919 struct sigaction sa; 3920 3921 sigaction(sig, NULL, &sa); 3922 3923 // See comment for SIGNIFICANT_SIGNAL_MASK define 3924 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 3925 3926 st->print("%s: ", os::exception_name(sig, buf, buflen)); 3927 3928 address handler = (sa.sa_flags & SA_SIGINFO) 3929 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 3930 : CAST_FROM_FN_PTR(address, sa.sa_handler); 3931 3932 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 3933 st->print("SIG_DFL"); 3934 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 3935 st->print("SIG_IGN"); 3936 } else { 3937 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 3938 } 3939 3940 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask); 3941 3942 address rh = VMError::get_resetted_sighandler(sig); 3943 // May be, handler was resetted by VMError? 3944 if(rh != NULL) { 3945 handler = rh; 3946 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 3947 } 3948 3949 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags); 3950 3951 // Check: is it our handler? 3952 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 3953 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 3954 // It is our signal handler 3955 // check for flags, reset system-used one! 3956 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 3957 st->print( 3958 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 3959 os::Linux::get_our_sigflags(sig)); 3960 } 3961 } 3962 st->cr(); 3963} 3964 3965 3966#define DO_SIGNAL_CHECK(sig) \ 3967 if (!sigismember(&check_signal_done, sig)) \ 3968 os::Linux::check_signal_handler(sig) 3969 3970// This method is a periodic task to check for misbehaving JNI applications 3971// under CheckJNI, we can add any periodic checks here 3972 3973void os::run_periodic_checks() { 3974 3975 if (check_signals == false) return; 3976 3977 // SEGV and BUS if overridden could potentially prevent 3978 // generation of hs*.log in the event of a crash, debugging 3979 // such a case can be very challenging, so we absolutely 3980 // check the following for a good measure: 3981 DO_SIGNAL_CHECK(SIGSEGV); 3982 DO_SIGNAL_CHECK(SIGILL); 3983 DO_SIGNAL_CHECK(SIGFPE); 3984 DO_SIGNAL_CHECK(SIGBUS); 3985 DO_SIGNAL_CHECK(SIGPIPE); 3986 DO_SIGNAL_CHECK(SIGXFSZ); 3987 3988 3989 // ReduceSignalUsage allows the user to override these handlers 3990 // see comments at the very top and jvm_solaris.h 3991 if (!ReduceSignalUsage) { 3992 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 3993 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 3994 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 3995 DO_SIGNAL_CHECK(BREAK_SIGNAL); 3996 } 3997 3998 DO_SIGNAL_CHECK(SR_signum); 3999 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4000} 4001 4002typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4003 4004static os_sigaction_t os_sigaction = NULL; 4005 4006void os::Linux::check_signal_handler(int sig) { 4007 char buf[O_BUFLEN]; 4008 address jvmHandler = NULL; 4009 4010 4011 struct sigaction act; 4012 if (os_sigaction == NULL) { 4013 // only trust the default sigaction, in case it has been interposed 4014 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4015 if (os_sigaction == NULL) return; 4016 } 4017 4018 os_sigaction(sig, (struct sigaction*)NULL, &act); 4019 4020 4021 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4022 4023 address thisHandler = (act.sa_flags & SA_SIGINFO) 4024 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4025 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 4026 4027 4028 switch(sig) { 4029 case SIGSEGV: 4030 case SIGBUS: 4031 case SIGFPE: 4032 case SIGPIPE: 4033 case SIGILL: 4034 case SIGXFSZ: 4035 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4036 break; 4037 4038 case SHUTDOWN1_SIGNAL: 4039 case SHUTDOWN2_SIGNAL: 4040 case SHUTDOWN3_SIGNAL: 4041 case BREAK_SIGNAL: 4042 jvmHandler = (address)user_handler(); 4043 break; 4044 4045 case INTERRUPT_SIGNAL: 4046 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4047 break; 4048 4049 default: 4050 if (sig == SR_signum) { 4051 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4052 } else { 4053 return; 4054 } 4055 break; 4056 } 4057 4058 if (thisHandler != jvmHandler) { 4059 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4060 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4061 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4062 // No need to check this sig any longer 4063 sigaddset(&check_signal_done, sig); 4064 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4065 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4066 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4067 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4068 // No need to check this sig any longer 4069 sigaddset(&check_signal_done, sig); 4070 } 4071 4072 // Dump all the signal 4073 if (sigismember(&check_signal_done, sig)) { 4074 print_signal_handlers(tty, buf, O_BUFLEN); 4075 } 4076} 4077 4078extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 4079 4080extern bool signal_name(int signo, char* buf, size_t len); 4081 4082const char* os::exception_name(int exception_code, char* buf, size_t size) { 4083 if (0 < exception_code && exception_code <= SIGRTMAX) { 4084 // signal 4085 if (!signal_name(exception_code, buf, size)) { 4086 jio_snprintf(buf, size, "SIG%d", exception_code); 4087 } 4088 return buf; 4089 } else { 4090 return NULL; 4091 } 4092} 4093 4094// this is called _before_ the most of global arguments have been parsed 4095void os::init(void) { 4096 char dummy; /* used to get a guess on initial stack address */ 4097// first_hrtime = gethrtime(); 4098 4099 // With LinuxThreads the JavaMain thread pid (primordial thread) 4100 // is different than the pid of the java launcher thread. 4101 // So, on Linux, the launcher thread pid is passed to the VM 4102 // via the sun.java.launcher.pid property. 4103 // Use this property instead of getpid() if it was correctly passed. 4104 // See bug 6351349. 4105 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4106 4107 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4108 4109 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4110 4111 init_random(1234567); 4112 4113 ThreadCritical::initialize(); 4114 4115 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4116 if (Linux::page_size() == -1) { 4117 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4118 strerror(errno))); 4119 } 4120 init_page_sizes((size_t) Linux::page_size()); 4121 4122 Linux::initialize_system_info(); 4123 4124 // main_thread points to the aboriginal thread 4125 Linux::_main_thread = pthread_self(); 4126 4127 Linux::clock_init(); 4128 initial_time_count = os::elapsed_counter(); 4129 pthread_mutex_init(&dl_mutex, NULL); 4130} 4131 4132// To install functions for atexit system call 4133extern "C" { 4134 static void perfMemory_exit_helper() { 4135 perfMemory_exit(); 4136 } 4137} 4138 4139// this is called _after_ the global arguments have been parsed 4140jint os::init_2(void) 4141{ 4142 Linux::fast_thread_clock_init(); 4143 4144 // Allocate a single page and mark it as readable for safepoint polling 4145 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4146 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 4147 4148 os::set_polling_page( polling_page ); 4149 4150#ifndef PRODUCT 4151 if(Verbose && PrintMiscellaneous) 4152 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 4153#endif 4154 4155 if (!UseMembar) { 4156 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4157 guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page"); 4158 os::set_memory_serialize_page( mem_serialize_page ); 4159 4160#ifndef PRODUCT 4161 if(Verbose && PrintMiscellaneous) 4162 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 4163#endif 4164 } 4165 4166 os::large_page_init(); 4167 4168 // initialize suspend/resume support - must do this before signal_sets_init() 4169 if (SR_initialize() != 0) { 4170 perror("SR_initialize failed"); 4171 return JNI_ERR; 4172 } 4173 4174 Linux::signal_sets_init(); 4175 Linux::install_signal_handlers(); 4176 4177 // Check minimum allowable stack size for thread creation and to initialize 4178 // the java system classes, including StackOverflowError - depends on page 4179 // size. Add a page for compiler2 recursion in main thread. 4180 // Add in 2*BytesPerWord times page size to account for VM stack during 4181 // class initialization depending on 32 or 64 bit VM. 4182 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4183 (size_t)(StackYellowPages+StackRedPages+StackShadowPages+ 4184 2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::page_size()); 4185 4186 size_t threadStackSizeInBytes = ThreadStackSize * K; 4187 if (threadStackSizeInBytes != 0 && 4188 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4189 tty->print_cr("\nThe stack size specified is too small, " 4190 "Specify at least %dk", 4191 os::Linux::min_stack_allowed/ K); 4192 return JNI_ERR; 4193 } 4194 4195 // Make the stack size a multiple of the page size so that 4196 // the yellow/red zones can be guarded. 4197 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4198 vm_page_size())); 4199 4200 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4201 4202 Linux::libpthread_init(); 4203 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4204 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4205 Linux::glibc_version(), Linux::libpthread_version(), 4206 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4207 } 4208 4209 if (UseNUMA) { 4210 if (!Linux::libnuma_init()) { 4211 UseNUMA = false; 4212 } else { 4213 if ((Linux::numa_max_node() < 1)) { 4214 // There's only one node(they start from 0), disable NUMA. 4215 UseNUMA = false; 4216 } 4217 } 4218 // With SHM large pages we cannot uncommit a page, so there's not way 4219 // we can make the adaptive lgrp chunk resizing work. If the user specified 4220 // both UseNUMA and UseLargePages (or UseSHM) on the command line - warn and 4221 // disable adaptive resizing. 4222 if (UseNUMA && UseLargePages && UseSHM) { 4223 if (!FLAG_IS_DEFAULT(UseNUMA)) { 4224 if (FLAG_IS_DEFAULT(UseLargePages) && FLAG_IS_DEFAULT(UseSHM)) { 4225 UseLargePages = false; 4226 } else { 4227 warning("UseNUMA is not fully compatible with SHM large pages, disabling adaptive resizing"); 4228 UseAdaptiveSizePolicy = false; 4229 UseAdaptiveNUMAChunkSizing = false; 4230 } 4231 } else { 4232 UseNUMA = false; 4233 } 4234 } 4235 if (!UseNUMA && ForceNUMA) { 4236 UseNUMA = true; 4237 } 4238 } 4239 4240 if (MaxFDLimit) { 4241 // set the number of file descriptors to max. print out error 4242 // if getrlimit/setrlimit fails but continue regardless. 4243 struct rlimit nbr_files; 4244 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4245 if (status != 0) { 4246 if (PrintMiscellaneous && (Verbose || WizardMode)) 4247 perror("os::init_2 getrlimit failed"); 4248 } else { 4249 nbr_files.rlim_cur = nbr_files.rlim_max; 4250 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4251 if (status != 0) { 4252 if (PrintMiscellaneous && (Verbose || WizardMode)) 4253 perror("os::init_2 setrlimit failed"); 4254 } 4255 } 4256 } 4257 4258 // Initialize lock used to serialize thread creation (see os::create_thread) 4259 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4260 4261 // at-exit methods are called in the reverse order of their registration. 4262 // atexit functions are called on return from main or as a result of a 4263 // call to exit(3C). There can be only 32 of these functions registered 4264 // and atexit() does not set errno. 4265 4266 if (PerfAllowAtExitRegistration) { 4267 // only register atexit functions if PerfAllowAtExitRegistration is set. 4268 // atexit functions can be delayed until process exit time, which 4269 // can be problematic for embedded VM situations. Embedded VMs should 4270 // call DestroyJavaVM() to assure that VM resources are released. 4271 4272 // note: perfMemory_exit_helper atexit function may be removed in 4273 // the future if the appropriate cleanup code can be added to the 4274 // VM_Exit VMOperation's doit method. 4275 if (atexit(perfMemory_exit_helper) != 0) { 4276 warning("os::init2 atexit(perfMemory_exit_helper) failed"); 4277 } 4278 } 4279 4280 // initialize thread priority policy 4281 prio_init(); 4282 4283 return JNI_OK; 4284} 4285 4286// this is called at the end of vm_initialization 4287void os::init_3(void) 4288{ 4289#ifdef JAVASE_EMBEDDED 4290 // Start the MemNotifyThread 4291 if (LowMemoryProtection) { 4292 MemNotifyThread::start(); 4293 } 4294 return; 4295#endif 4296} 4297 4298// Mark the polling page as unreadable 4299void os::make_polling_page_unreadable(void) { 4300 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 4301 fatal("Could not disable polling page"); 4302}; 4303 4304// Mark the polling page as readable 4305void os::make_polling_page_readable(void) { 4306 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4307 fatal("Could not enable polling page"); 4308 } 4309}; 4310 4311int os::active_processor_count() { 4312 // Linux doesn't yet have a (official) notion of processor sets, 4313 // so just return the number of online processors. 4314 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4315 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4316 return online_cpus; 4317} 4318 4319void os::set_native_thread_name(const char *name) { 4320 // Not yet implemented. 4321 return; 4322} 4323 4324bool os::distribute_processes(uint length, uint* distribution) { 4325 // Not yet implemented. 4326 return false; 4327} 4328 4329bool os::bind_to_processor(uint processor_id) { 4330 // Not yet implemented. 4331 return false; 4332} 4333 4334/// 4335 4336// Suspends the target using the signal mechanism and then grabs the PC before 4337// resuming the target. Used by the flat-profiler only 4338ExtendedPC os::get_thread_pc(Thread* thread) { 4339 // Make sure that it is called by the watcher for the VMThread 4340 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4341 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4342 4343 ExtendedPC epc; 4344 4345 OSThread* osthread = thread->osthread(); 4346 if (do_suspend(osthread)) { 4347 if (osthread->ucontext() != NULL) { 4348 epc = os::Linux::ucontext_get_pc(osthread->ucontext()); 4349 } else { 4350 // NULL context is unexpected, double-check this is the VMThread 4351 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4352 } 4353 do_resume(osthread); 4354 } 4355 // failure means pthread_kill failed for some reason - arguably this is 4356 // a fatal problem, but such problems are ignored elsewhere 4357 4358 return epc; 4359} 4360 4361int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 4362{ 4363 if (is_NPTL()) { 4364 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4365 } else { 4366 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4367 // word back to default 64bit precision if condvar is signaled. Java 4368 // wants 53bit precision. Save and restore current value. 4369 int fpu = get_fpu_control_word(); 4370 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4371 set_fpu_control_word(fpu); 4372 return status; 4373 } 4374} 4375 4376//////////////////////////////////////////////////////////////////////////////// 4377// debug support 4378 4379static address same_page(address x, address y) { 4380 int page_bits = -os::vm_page_size(); 4381 if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits)) 4382 return x; 4383 else if (x > y) 4384 return (address)(intptr_t(y) | ~page_bits) + 1; 4385 else 4386 return (address)(intptr_t(y) & page_bits); 4387} 4388 4389bool os::find(address addr, outputStream* st) { 4390 Dl_info dlinfo; 4391 memset(&dlinfo, 0, sizeof(dlinfo)); 4392 if (dladdr(addr, &dlinfo)) { 4393 st->print(PTR_FORMAT ": ", addr); 4394 if (dlinfo.dli_sname != NULL) { 4395 st->print("%s+%#x", dlinfo.dli_sname, 4396 addr - (intptr_t)dlinfo.dli_saddr); 4397 } else if (dlinfo.dli_fname) { 4398 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4399 } else { 4400 st->print("<absolute address>"); 4401 } 4402 if (dlinfo.dli_fname) { 4403 st->print(" in %s", dlinfo.dli_fname); 4404 } 4405 if (dlinfo.dli_fbase) { 4406 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4407 } 4408 st->cr(); 4409 4410 if (Verbose) { 4411 // decode some bytes around the PC 4412 address begin = same_page(addr-40, addr); 4413 address end = same_page(addr+40, addr); 4414 address lowest = (address) dlinfo.dli_sname; 4415 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4416 if (begin < lowest) begin = lowest; 4417 Dl_info dlinfo2; 4418 if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr 4419 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 4420 end = (address) dlinfo2.dli_saddr; 4421 Disassembler::decode(begin, end, st); 4422 } 4423 return true; 4424 } 4425 return false; 4426} 4427 4428//////////////////////////////////////////////////////////////////////////////// 4429// misc 4430 4431// This does not do anything on Linux. This is basically a hook for being 4432// able to use structured exception handling (thread-local exception filters) 4433// on, e.g., Win32. 4434void 4435os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 4436 JavaCallArguments* args, Thread* thread) { 4437 f(value, method, args, thread); 4438} 4439 4440void os::print_statistics() { 4441} 4442 4443int os::message_box(const char* title, const char* message) { 4444 int i; 4445 fdStream err(defaultStream::error_fd()); 4446 for (i = 0; i < 78; i++) err.print_raw("="); 4447 err.cr(); 4448 err.print_raw_cr(title); 4449 for (i = 0; i < 78; i++) err.print_raw("-"); 4450 err.cr(); 4451 err.print_raw_cr(message); 4452 for (i = 0; i < 78; i++) err.print_raw("="); 4453 err.cr(); 4454 4455 char buf[16]; 4456 // Prevent process from exiting upon "read error" without consuming all CPU 4457 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 4458 4459 return buf[0] == 'y' || buf[0] == 'Y'; 4460} 4461 4462int os::stat(const char *path, struct stat *sbuf) { 4463 char pathbuf[MAX_PATH]; 4464 if (strlen(path) > MAX_PATH - 1) { 4465 errno = ENAMETOOLONG; 4466 return -1; 4467 } 4468 os::native_path(strcpy(pathbuf, path)); 4469 return ::stat(pathbuf, sbuf); 4470} 4471 4472bool os::check_heap(bool force) { 4473 return true; 4474} 4475 4476int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 4477 return ::vsnprintf(buf, count, format, args); 4478} 4479 4480// Is a (classpath) directory empty? 4481bool os::dir_is_empty(const char* path) { 4482 DIR *dir = NULL; 4483 struct dirent *ptr; 4484 4485 dir = opendir(path); 4486 if (dir == NULL) return true; 4487 4488 /* Scan the directory */ 4489 bool result = true; 4490 char buf[sizeof(struct dirent) + MAX_PATH]; 4491 while (result && (ptr = ::readdir(dir)) != NULL) { 4492 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 4493 result = false; 4494 } 4495 } 4496 closedir(dir); 4497 return result; 4498} 4499 4500// This code originates from JDK's sysOpen and open64_w 4501// from src/solaris/hpi/src/system_md.c 4502 4503#ifndef O_DELETE 4504#define O_DELETE 0x10000 4505#endif 4506 4507// Open a file. Unlink the file immediately after open returns 4508// if the specified oflag has the O_DELETE flag set. 4509// O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c 4510 4511int os::open(const char *path, int oflag, int mode) { 4512 4513 if (strlen(path) > MAX_PATH - 1) { 4514 errno = ENAMETOOLONG; 4515 return -1; 4516 } 4517 int fd; 4518 int o_delete = (oflag & O_DELETE); 4519 oflag = oflag & ~O_DELETE; 4520 4521 fd = ::open64(path, oflag, mode); 4522 if (fd == -1) return -1; 4523 4524 //If the open succeeded, the file might still be a directory 4525 { 4526 struct stat64 buf64; 4527 int ret = ::fstat64(fd, &buf64); 4528 int st_mode = buf64.st_mode; 4529 4530 if (ret != -1) { 4531 if ((st_mode & S_IFMT) == S_IFDIR) { 4532 errno = EISDIR; 4533 ::close(fd); 4534 return -1; 4535 } 4536 } else { 4537 ::close(fd); 4538 return -1; 4539 } 4540 } 4541 4542 /* 4543 * All file descriptors that are opened in the JVM and not 4544 * specifically destined for a subprocess should have the 4545 * close-on-exec flag set. If we don't set it, then careless 3rd 4546 * party native code might fork and exec without closing all 4547 * appropriate file descriptors (e.g. as we do in closeDescriptors in 4548 * UNIXProcess.c), and this in turn might: 4549 * 4550 * - cause end-of-file to fail to be detected on some file 4551 * descriptors, resulting in mysterious hangs, or 4552 * 4553 * - might cause an fopen in the subprocess to fail on a system 4554 * suffering from bug 1085341. 4555 * 4556 * (Yes, the default setting of the close-on-exec flag is a Unix 4557 * design flaw) 4558 * 4559 * See: 4560 * 1085341: 32-bit stdio routines should support file descriptors >255 4561 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed 4562 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 4563 */ 4564#ifdef FD_CLOEXEC 4565 { 4566 int flags = ::fcntl(fd, F_GETFD); 4567 if (flags != -1) 4568 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 4569 } 4570#endif 4571 4572 if (o_delete != 0) { 4573 ::unlink(path); 4574 } 4575 return fd; 4576} 4577 4578 4579// create binary file, rewriting existing file if required 4580int os::create_binary_file(const char* path, bool rewrite_existing) { 4581 int oflags = O_WRONLY | O_CREAT; 4582 if (!rewrite_existing) { 4583 oflags |= O_EXCL; 4584 } 4585 return ::open64(path, oflags, S_IREAD | S_IWRITE); 4586} 4587 4588// return current position of file pointer 4589jlong os::current_file_offset(int fd) { 4590 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 4591} 4592 4593// move file pointer to the specified offset 4594jlong os::seek_to_file_offset(int fd, jlong offset) { 4595 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 4596} 4597 4598// This code originates from JDK's sysAvailable 4599// from src/solaris/hpi/src/native_threads/src/sys_api_td.c 4600 4601int os::available(int fd, jlong *bytes) { 4602 jlong cur, end; 4603 int mode; 4604 struct stat64 buf64; 4605 4606 if (::fstat64(fd, &buf64) >= 0) { 4607 mode = buf64.st_mode; 4608 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 4609 /* 4610 * XXX: is the following call interruptible? If so, this might 4611 * need to go through the INTERRUPT_IO() wrapper as for other 4612 * blocking, interruptible calls in this file. 4613 */ 4614 int n; 4615 if (::ioctl(fd, FIONREAD, &n) >= 0) { 4616 *bytes = n; 4617 return 1; 4618 } 4619 } 4620 } 4621 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 4622 return 0; 4623 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 4624 return 0; 4625 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 4626 return 0; 4627 } 4628 *bytes = end - cur; 4629 return 1; 4630} 4631 4632int os::socket_available(int fd, jint *pbytes) { 4633 // Linux doc says EINTR not returned, unlike Solaris 4634 int ret = ::ioctl(fd, FIONREAD, pbytes); 4635 4636 //%% note ioctl can return 0 when successful, JVM_SocketAvailable 4637 // is expected to return 0 on failure and 1 on success to the jdk. 4638 return (ret < 0) ? 0 : 1; 4639} 4640 4641// Map a block of memory. 4642char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 4643 char *addr, size_t bytes, bool read_only, 4644 bool allow_exec) { 4645 int prot; 4646 int flags = MAP_PRIVATE; 4647 4648 if (read_only) { 4649 prot = PROT_READ; 4650 } else { 4651 prot = PROT_READ | PROT_WRITE; 4652 } 4653 4654 if (allow_exec) { 4655 prot |= PROT_EXEC; 4656 } 4657 4658 if (addr != NULL) { 4659 flags |= MAP_FIXED; 4660 } 4661 4662 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 4663 fd, file_offset); 4664 if (mapped_address == MAP_FAILED) { 4665 return NULL; 4666 } 4667 return mapped_address; 4668} 4669 4670 4671// Remap a block of memory. 4672char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 4673 char *addr, size_t bytes, bool read_only, 4674 bool allow_exec) { 4675 // same as map_memory() on this OS 4676 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 4677 allow_exec); 4678} 4679 4680 4681// Unmap a block of memory. 4682bool os::pd_unmap_memory(char* addr, size_t bytes) { 4683 return munmap(addr, bytes) == 0; 4684} 4685 4686static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 4687 4688static clockid_t thread_cpu_clockid(Thread* thread) { 4689 pthread_t tid = thread->osthread()->pthread_id(); 4690 clockid_t clockid; 4691 4692 // Get thread clockid 4693 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 4694 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 4695 return clockid; 4696} 4697 4698// current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 4699// are used by JVM M&M and JVMTI to get user+sys or user CPU time 4700// of a thread. 4701// 4702// current_thread_cpu_time() and thread_cpu_time(Thread*) returns 4703// the fast estimate available on the platform. 4704 4705jlong os::current_thread_cpu_time() { 4706 if (os::Linux::supports_fast_thread_cpu_time()) { 4707 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4708 } else { 4709 // return user + sys since the cost is the same 4710 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 4711 } 4712} 4713 4714jlong os::thread_cpu_time(Thread* thread) { 4715 // consistent with what current_thread_cpu_time() returns 4716 if (os::Linux::supports_fast_thread_cpu_time()) { 4717 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4718 } else { 4719 return slow_thread_cpu_time(thread, true /* user + sys */); 4720 } 4721} 4722 4723jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 4724 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4725 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4726 } else { 4727 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 4728 } 4729} 4730 4731jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4732 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4733 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4734 } else { 4735 return slow_thread_cpu_time(thread, user_sys_cpu_time); 4736 } 4737} 4738 4739// 4740// -1 on error. 4741// 4742 4743static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4744 static bool proc_pid_cpu_avail = true; 4745 static bool proc_task_unchecked = true; 4746 static const char *proc_stat_path = "/proc/%d/stat"; 4747 pid_t tid = thread->osthread()->thread_id(); 4748 int i; 4749 char *s; 4750 char stat[2048]; 4751 int statlen; 4752 char proc_name[64]; 4753 int count; 4754 long sys_time, user_time; 4755 char string[64]; 4756 char cdummy; 4757 int idummy; 4758 long ldummy; 4759 FILE *fp; 4760 4761 // We first try accessing /proc/<pid>/cpu since this is faster to 4762 // process. If this file is not present (linux kernels 2.5 and above) 4763 // then we open /proc/<pid>/stat. 4764 if ( proc_pid_cpu_avail ) { 4765 sprintf(proc_name, "/proc/%d/cpu", tid); 4766 fp = fopen(proc_name, "r"); 4767 if ( fp != NULL ) { 4768 count = fscanf( fp, "%s %lu %lu\n", string, &user_time, &sys_time); 4769 fclose(fp); 4770 if ( count != 3 ) return -1; 4771 4772 if (user_sys_cpu_time) { 4773 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 4774 } else { 4775 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 4776 } 4777 } 4778 else proc_pid_cpu_avail = false; 4779 } 4780 4781 // The /proc/<tid>/stat aggregates per-process usage on 4782 // new Linux kernels 2.6+ where NPTL is supported. 4783 // The /proc/self/task/<tid>/stat still has the per-thread usage. 4784 // See bug 6328462. 4785 // There can be no directory /proc/self/task on kernels 2.4 with NPTL 4786 // and possibly in some other cases, so we check its availability. 4787 if (proc_task_unchecked && os::Linux::is_NPTL()) { 4788 // This is executed only once 4789 proc_task_unchecked = false; 4790 fp = fopen("/proc/self/task", "r"); 4791 if (fp != NULL) { 4792 proc_stat_path = "/proc/self/task/%d/stat"; 4793 fclose(fp); 4794 } 4795 } 4796 4797 sprintf(proc_name, proc_stat_path, tid); 4798 fp = fopen(proc_name, "r"); 4799 if ( fp == NULL ) return -1; 4800 statlen = fread(stat, 1, 2047, fp); 4801 stat[statlen] = '\0'; 4802 fclose(fp); 4803 4804 // Skip pid and the command string. Note that we could be dealing with 4805 // weird command names, e.g. user could decide to rename java launcher 4806 // to "java 1.4.2 :)", then the stat file would look like 4807 // 1234 (java 1.4.2 :)) R ... ... 4808 // We don't really need to know the command string, just find the last 4809 // occurrence of ")" and then start parsing from there. See bug 4726580. 4810 s = strrchr(stat, ')'); 4811 i = 0; 4812 if (s == NULL ) return -1; 4813 4814 // Skip blank chars 4815 do s++; while (isspace(*s)); 4816 4817 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 4818 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 4819 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 4820 &user_time, &sys_time); 4821 if ( count != 13 ) return -1; 4822 if (user_sys_cpu_time) { 4823 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 4824 } else { 4825 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 4826 } 4827} 4828 4829void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4830 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4831 info_ptr->may_skip_backward = false; // elapsed time not wall time 4832 info_ptr->may_skip_forward = false; // elapsed time not wall time 4833 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4834} 4835 4836void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4837 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4838 info_ptr->may_skip_backward = false; // elapsed time not wall time 4839 info_ptr->may_skip_forward = false; // elapsed time not wall time 4840 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4841} 4842 4843bool os::is_thread_cpu_time_supported() { 4844 return true; 4845} 4846 4847// System loadavg support. Returns -1 if load average cannot be obtained. 4848// Linux doesn't yet have a (official) notion of processor sets, 4849// so just return the system wide load average. 4850int os::loadavg(double loadavg[], int nelem) { 4851 return ::getloadavg(loadavg, nelem); 4852} 4853 4854void os::pause() { 4855 char filename[MAX_PATH]; 4856 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 4857 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 4858 } else { 4859 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 4860 } 4861 4862 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 4863 if (fd != -1) { 4864 struct stat buf; 4865 ::close(fd); 4866 while (::stat(filename, &buf) == 0) { 4867 (void)::poll(NULL, 0, 100); 4868 } 4869 } else { 4870 jio_fprintf(stderr, 4871 "Could not open pause file '%s', continuing immediately.\n", filename); 4872 } 4873} 4874 4875 4876// Refer to the comments in os_solaris.cpp park-unpark. 4877// 4878// Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 4879// hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 4880// For specifics regarding the bug see GLIBC BUGID 261237 : 4881// http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 4882// Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 4883// will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 4884// is used. (The simple C test-case provided in the GLIBC bug report manifests the 4885// hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 4886// and monitorenter when we're using 1-0 locking. All those operations may result in 4887// calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 4888// of libpthread avoids the problem, but isn't practical. 4889// 4890// Possible remedies: 4891// 4892// 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 4893// This is palliative and probabilistic, however. If the thread is preempted 4894// between the call to compute_abstime() and pthread_cond_timedwait(), more 4895// than the minimum period may have passed, and the abstime may be stale (in the 4896// past) resultin in a hang. Using this technique reduces the odds of a hang 4897// but the JVM is still vulnerable, particularly on heavily loaded systems. 4898// 4899// 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 4900// of the usual flag-condvar-mutex idiom. The write side of the pipe is set 4901// NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 4902// reduces to poll()+read(). This works well, but consumes 2 FDs per extant 4903// thread. 4904// 4905// 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 4906// that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 4907// a timeout request to the chron thread and then blocking via pthread_cond_wait(). 4908// This also works well. In fact it avoids kernel-level scalability impediments 4909// on certain platforms that don't handle lots of active pthread_cond_timedwait() 4910// timers in a graceful fashion. 4911// 4912// 4. When the abstime value is in the past it appears that control returns 4913// correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 4914// Subsequent timedwait/wait calls may hang indefinitely. Given that, we 4915// can avoid the problem by reinitializing the condvar -- by cond_destroy() 4916// followed by cond_init() -- after all calls to pthread_cond_timedwait(). 4917// It may be possible to avoid reinitialization by checking the return 4918// value from pthread_cond_timedwait(). In addition to reinitializing the 4919// condvar we must establish the invariant that cond_signal() is only called 4920// within critical sections protected by the adjunct mutex. This prevents 4921// cond_signal() from "seeing" a condvar that's in the midst of being 4922// reinitialized or that is corrupt. Sadly, this invariant obviates the 4923// desirable signal-after-unlock optimization that avoids futile context switching. 4924// 4925// I'm also concerned that some versions of NTPL might allocate an auxilliary 4926// structure when a condvar is used or initialized. cond_destroy() would 4927// release the helper structure. Our reinitialize-after-timedwait fix 4928// put excessive stress on malloc/free and locks protecting the c-heap. 4929// 4930// We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 4931// It may be possible to refine (4) by checking the kernel and NTPL verisons 4932// and only enabling the work-around for vulnerable environments. 4933 4934// utility to compute the abstime argument to timedwait: 4935// millis is the relative timeout time 4936// abstime will be the absolute timeout time 4937// TODO: replace compute_abstime() with unpackTime() 4938 4939static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 4940 if (millis < 0) millis = 0; 4941 struct timeval now; 4942 int status = gettimeofday(&now, NULL); 4943 assert(status == 0, "gettimeofday"); 4944 jlong seconds = millis / 1000; 4945 millis %= 1000; 4946 if (seconds > 50000000) { // see man cond_timedwait(3T) 4947 seconds = 50000000; 4948 } 4949 abstime->tv_sec = now.tv_sec + seconds; 4950 long usec = now.tv_usec + millis * 1000; 4951 if (usec >= 1000000) { 4952 abstime->tv_sec += 1; 4953 usec -= 1000000; 4954 } 4955 abstime->tv_nsec = usec * 1000; 4956 return abstime; 4957} 4958 4959 4960// Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 4961// Conceptually TryPark() should be equivalent to park(0). 4962 4963int os::PlatformEvent::TryPark() { 4964 for (;;) { 4965 const int v = _Event ; 4966 guarantee ((v == 0) || (v == 1), "invariant") ; 4967 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 4968 } 4969} 4970 4971void os::PlatformEvent::park() { // AKA "down()" 4972 // Invariant: Only the thread associated with the Event/PlatformEvent 4973 // may call park(). 4974 // TODO: assert that _Assoc != NULL or _Assoc == Self 4975 int v ; 4976 for (;;) { 4977 v = _Event ; 4978 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 4979 } 4980 guarantee (v >= 0, "invariant") ; 4981 if (v == 0) { 4982 // Do this the hard way by blocking ... 4983 int status = pthread_mutex_lock(_mutex); 4984 assert_status(status == 0, status, "mutex_lock"); 4985 guarantee (_nParked == 0, "invariant") ; 4986 ++ _nParked ; 4987 while (_Event < 0) { 4988 status = pthread_cond_wait(_cond, _mutex); 4989 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 4990 // Treat this the same as if the wait was interrupted 4991 if (status == ETIME) { status = EINTR; } 4992 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 4993 } 4994 -- _nParked ; 4995 4996 _Event = 0 ; 4997 status = pthread_mutex_unlock(_mutex); 4998 assert_status(status == 0, status, "mutex_unlock"); 4999 // Paranoia to ensure our locked and lock-free paths interact 5000 // correctly with each other. 5001 OrderAccess::fence(); 5002 } 5003 guarantee (_Event >= 0, "invariant") ; 5004} 5005 5006int os::PlatformEvent::park(jlong millis) { 5007 guarantee (_nParked == 0, "invariant") ; 5008 5009 int v ; 5010 for (;;) { 5011 v = _Event ; 5012 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5013 } 5014 guarantee (v >= 0, "invariant") ; 5015 if (v != 0) return OS_OK ; 5016 5017 // We do this the hard way, by blocking the thread. 5018 // Consider enforcing a minimum timeout value. 5019 struct timespec abst; 5020 compute_abstime(&abst, millis); 5021 5022 int ret = OS_TIMEOUT; 5023 int status = pthread_mutex_lock(_mutex); 5024 assert_status(status == 0, status, "mutex_lock"); 5025 guarantee (_nParked == 0, "invariant") ; 5026 ++_nParked ; 5027 5028 // Object.wait(timo) will return because of 5029 // (a) notification 5030 // (b) timeout 5031 // (c) thread.interrupt 5032 // 5033 // Thread.interrupt and object.notify{All} both call Event::set. 5034 // That is, we treat thread.interrupt as a special case of notification. 5035 // The underlying Solaris implementation, cond_timedwait, admits 5036 // spurious/premature wakeups, but the JLS/JVM spec prevents the 5037 // JVM from making those visible to Java code. As such, we must 5038 // filter out spurious wakeups. We assume all ETIME returns are valid. 5039 // 5040 // TODO: properly differentiate simultaneous notify+interrupt. 5041 // In that case, we should propagate the notify to another waiter. 5042 5043 while (_Event < 0) { 5044 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5045 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5046 pthread_cond_destroy (_cond); 5047 pthread_cond_init (_cond, NULL) ; 5048 } 5049 assert_status(status == 0 || status == EINTR || 5050 status == ETIME || status == ETIMEDOUT, 5051 status, "cond_timedwait"); 5052 if (!FilterSpuriousWakeups) break ; // previous semantics 5053 if (status == ETIME || status == ETIMEDOUT) break ; 5054 // We consume and ignore EINTR and spurious wakeups. 5055 } 5056 --_nParked ; 5057 if (_Event >= 0) { 5058 ret = OS_OK; 5059 } 5060 _Event = 0 ; 5061 status = pthread_mutex_unlock(_mutex); 5062 assert_status(status == 0, status, "mutex_unlock"); 5063 assert (_nParked == 0, "invariant") ; 5064 // Paranoia to ensure our locked and lock-free paths interact 5065 // correctly with each other. 5066 OrderAccess::fence(); 5067 return ret; 5068} 5069 5070void os::PlatformEvent::unpark() { 5071 // Transitions for _Event: 5072 // 0 :=> 1 5073 // 1 :=> 1 5074 // -1 :=> either 0 or 1; must signal target thread 5075 // That is, we can safely transition _Event from -1 to either 5076 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back 5077 // unpark() calls. 5078 // See also: "Semaphores in Plan 9" by Mullender & Cox 5079 // 5080 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5081 // that it will take two back-to-back park() calls for the owning 5082 // thread to block. This has the benefit of forcing a spurious return 5083 // from the first park() call after an unpark() call which will help 5084 // shake out uses of park() and unpark() without condition variables. 5085 5086 if (Atomic::xchg(1, &_Event) >= 0) return; 5087 5088 // Wait for the thread associated with the event to vacate 5089 int status = pthread_mutex_lock(_mutex); 5090 assert_status(status == 0, status, "mutex_lock"); 5091 int AnyWaiters = _nParked; 5092 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5093 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5094 AnyWaiters = 0; 5095 pthread_cond_signal(_cond); 5096 } 5097 status = pthread_mutex_unlock(_mutex); 5098 assert_status(status == 0, status, "mutex_unlock"); 5099 if (AnyWaiters != 0) { 5100 status = pthread_cond_signal(_cond); 5101 assert_status(status == 0, status, "cond_signal"); 5102 } 5103 5104 // Note that we signal() _after dropping the lock for "immortal" Events. 5105 // This is safe and avoids a common class of futile wakeups. In rare 5106 // circumstances this can cause a thread to return prematurely from 5107 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 5108 // simply re-test the condition and re-park itself. 5109} 5110 5111 5112// JSR166 5113// ------------------------------------------------------- 5114 5115/* 5116 * The solaris and linux implementations of park/unpark are fairly 5117 * conservative for now, but can be improved. They currently use a 5118 * mutex/condvar pair, plus a a count. 5119 * Park decrements count if > 0, else does a condvar wait. Unpark 5120 * sets count to 1 and signals condvar. Only one thread ever waits 5121 * on the condvar. Contention seen when trying to park implies that someone 5122 * is unparking you, so don't wait. And spurious returns are fine, so there 5123 * is no need to track notifications. 5124 */ 5125 5126#define MAX_SECS 100000000 5127/* 5128 * This code is common to linux and solaris and will be moved to a 5129 * common place in dolphin. 5130 * 5131 * The passed in time value is either a relative time in nanoseconds 5132 * or an absolute time in milliseconds. Either way it has to be unpacked 5133 * into suitable seconds and nanoseconds components and stored in the 5134 * given timespec structure. 5135 * Given time is a 64-bit value and the time_t used in the timespec is only 5136 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 5137 * overflow if times way in the future are given. Further on Solaris versions 5138 * prior to 10 there is a restriction (see cond_timedwait) that the specified 5139 * number of seconds, in abstime, is less than current_time + 100,000,000. 5140 * As it will be 28 years before "now + 100000000" will overflow we can 5141 * ignore overflow and just impose a hard-limit on seconds using the value 5142 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 5143 * years from "now". 5144 */ 5145 5146static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5147 assert (time > 0, "convertTime"); 5148 5149 struct timeval now; 5150 int status = gettimeofday(&now, NULL); 5151 assert(status == 0, "gettimeofday"); 5152 5153 time_t max_secs = now.tv_sec + MAX_SECS; 5154 5155 if (isAbsolute) { 5156 jlong secs = time / 1000; 5157 if (secs > max_secs) { 5158 absTime->tv_sec = max_secs; 5159 } 5160 else { 5161 absTime->tv_sec = secs; 5162 } 5163 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5164 } 5165 else { 5166 jlong secs = time / NANOSECS_PER_SEC; 5167 if (secs >= MAX_SECS) { 5168 absTime->tv_sec = max_secs; 5169 absTime->tv_nsec = 0; 5170 } 5171 else { 5172 absTime->tv_sec = now.tv_sec + secs; 5173 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5174 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5175 absTime->tv_nsec -= NANOSECS_PER_SEC; 5176 ++absTime->tv_sec; // note: this must be <= max_secs 5177 } 5178 } 5179 } 5180 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5181 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5182 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5183 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5184} 5185 5186void Parker::park(bool isAbsolute, jlong time) { 5187 // Ideally we'd do something useful while spinning, such 5188 // as calling unpackTime(). 5189 5190 // Optional fast-path check: 5191 // Return immediately if a permit is available. 5192 // We depend on Atomic::xchg() having full barrier semantics 5193 // since we are doing a lock-free update to _counter. 5194 if (Atomic::xchg(0, &_counter) > 0) return; 5195 5196 Thread* thread = Thread::current(); 5197 assert(thread->is_Java_thread(), "Must be JavaThread"); 5198 JavaThread *jt = (JavaThread *)thread; 5199 5200 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5201 // Check interrupt before trying to wait 5202 if (Thread::is_interrupted(thread, false)) { 5203 return; 5204 } 5205 5206 // Next, demultiplex/decode time arguments 5207 timespec absTime; 5208 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all 5209 return; 5210 } 5211 if (time > 0) { 5212 unpackTime(&absTime, isAbsolute, time); 5213 } 5214 5215 5216 // Enter safepoint region 5217 // Beware of deadlocks such as 6317397. 5218 // The per-thread Parker:: mutex is a classic leaf-lock. 5219 // In particular a thread must never block on the Threads_lock while 5220 // holding the Parker:: mutex. If safepoints are pending both the 5221 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5222 ThreadBlockInVM tbivm(jt); 5223 5224 // Don't wait if cannot get lock since interference arises from 5225 // unblocking. Also. check interrupt before trying wait 5226 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5227 return; 5228 } 5229 5230 int status ; 5231 if (_counter > 0) { // no wait needed 5232 _counter = 0; 5233 status = pthread_mutex_unlock(_mutex); 5234 assert (status == 0, "invariant") ; 5235 // Paranoia to ensure our locked and lock-free paths interact 5236 // correctly with each other and Java-level accesses. 5237 OrderAccess::fence(); 5238 return; 5239 } 5240 5241#ifdef ASSERT 5242 // Don't catch signals while blocked; let the running threads have the signals. 5243 // (This allows a debugger to break into the running thread.) 5244 sigset_t oldsigs; 5245 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5246 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5247#endif 5248 5249 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5250 jt->set_suspend_equivalent(); 5251 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5252 5253 if (time == 0) { 5254 status = pthread_cond_wait (_cond, _mutex) ; 5255 } else { 5256 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ; 5257 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5258 pthread_cond_destroy (_cond) ; 5259 pthread_cond_init (_cond, NULL); 5260 } 5261 } 5262 assert_status(status == 0 || status == EINTR || 5263 status == ETIME || status == ETIMEDOUT, 5264 status, "cond_timedwait"); 5265 5266#ifdef ASSERT 5267 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5268#endif 5269 5270 _counter = 0 ; 5271 status = pthread_mutex_unlock(_mutex) ; 5272 assert_status(status == 0, status, "invariant") ; 5273 // Paranoia to ensure our locked and lock-free paths interact 5274 // correctly with each other and Java-level accesses. 5275 OrderAccess::fence(); 5276 5277 // If externally suspended while waiting, re-suspend 5278 if (jt->handle_special_suspend_equivalent_condition()) { 5279 jt->java_suspend_self(); 5280 } 5281} 5282 5283void Parker::unpark() { 5284 int s, status ; 5285 status = pthread_mutex_lock(_mutex); 5286 assert (status == 0, "invariant") ; 5287 s = _counter; 5288 _counter = 1; 5289 if (s < 1) { 5290 if (WorkAroundNPTLTimedWaitHang) { 5291 status = pthread_cond_signal (_cond) ; 5292 assert (status == 0, "invariant") ; 5293 status = pthread_mutex_unlock(_mutex); 5294 assert (status == 0, "invariant") ; 5295 } else { 5296 status = pthread_mutex_unlock(_mutex); 5297 assert (status == 0, "invariant") ; 5298 status = pthread_cond_signal (_cond) ; 5299 assert (status == 0, "invariant") ; 5300 } 5301 } else { 5302 pthread_mutex_unlock(_mutex); 5303 assert (status == 0, "invariant") ; 5304 } 5305} 5306 5307 5308extern char** environ; 5309 5310#ifndef __NR_fork 5311#define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5312#endif 5313 5314#ifndef __NR_execve 5315#define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 5316#endif 5317 5318// Run the specified command in a separate process. Return its exit value, 5319// or -1 on failure (e.g. can't fork a new process). 5320// Unlike system(), this function can be called from signal handler. It 5321// doesn't block SIGINT et al. 5322int os::fork_and_exec(char* cmd) { 5323 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5324 5325 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5326 // pthread_atfork handlers and reset pthread library. All we need is a 5327 // separate process to execve. Make a direct syscall to fork process. 5328 // On IA64 there's no fork syscall, we have to use fork() and hope for 5329 // the best... 5330 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5331 IA64_ONLY(fork();) 5332 5333 if (pid < 0) { 5334 // fork failed 5335 return -1; 5336 5337 } else if (pid == 0) { 5338 // child process 5339 5340 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5341 // first to kill every thread on the thread list. Because this list is 5342 // not reset by fork() (see notes above), execve() will instead kill 5343 // every thread in the parent process. We know this is the only thread 5344 // in the new process, so make a system call directly. 5345 // IA64 should use normal execve() from glibc to match the glibc fork() 5346 // above. 5347 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5348 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5349 5350 // execve failed 5351 _exit(-1); 5352 5353 } else { 5354 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5355 // care about the actual exit code, for now. 5356 5357 int status; 5358 5359 // Wait for the child process to exit. This returns immediately if 5360 // the child has already exited. */ 5361 while (waitpid(pid, &status, 0) < 0) { 5362 switch (errno) { 5363 case ECHILD: return 0; 5364 case EINTR: break; 5365 default: return -1; 5366 } 5367 } 5368 5369 if (WIFEXITED(status)) { 5370 // The child exited normally; get its exit code. 5371 return WEXITSTATUS(status); 5372 } else if (WIFSIGNALED(status)) { 5373 // The child exited because of a signal 5374 // The best value to return is 0x80 + signal number, 5375 // because that is what all Unix shells do, and because 5376 // it allows callers to distinguish between process exit and 5377 // process death by signal. 5378 return 0x80 + WTERMSIG(status); 5379 } else { 5380 // Unknown exit code; pass it through 5381 return status; 5382 } 5383 } 5384} 5385 5386// is_headless_jre() 5387// 5388// Test for the existence of xawt/libmawt.so or libawt_xawt.so 5389// in order to report if we are running in a headless jre 5390// 5391// Since JDK8 xawt/libmawt.so was moved into the same directory 5392// as libawt.so, and renamed libawt_xawt.so 5393// 5394bool os::is_headless_jre() { 5395 struct stat statbuf; 5396 char buf[MAXPATHLEN]; 5397 char libmawtpath[MAXPATHLEN]; 5398 const char *xawtstr = "/xawt/libmawt.so"; 5399 const char *new_xawtstr = "/libawt_xawt.so"; 5400 char *p; 5401 5402 // Get path to libjvm.so 5403 os::jvm_path(buf, sizeof(buf)); 5404 5405 // Get rid of libjvm.so 5406 p = strrchr(buf, '/'); 5407 if (p == NULL) return false; 5408 else *p = '\0'; 5409 5410 // Get rid of client or server 5411 p = strrchr(buf, '/'); 5412 if (p == NULL) return false; 5413 else *p = '\0'; 5414 5415 // check xawt/libmawt.so 5416 strcpy(libmawtpath, buf); 5417 strcat(libmawtpath, xawtstr); 5418 if (::stat(libmawtpath, &statbuf) == 0) return false; 5419 5420 // check libawt_xawt.so 5421 strcpy(libmawtpath, buf); 5422 strcat(libmawtpath, new_xawtstr); 5423 if (::stat(libmawtpath, &statbuf) == 0) return false; 5424 5425 return true; 5426} 5427 5428// Get the default path to the core file 5429// Returns the length of the string 5430int os::get_core_path(char* buffer, size_t bufferSize) { 5431 const char* p = get_current_directory(buffer, bufferSize); 5432 5433 if (p == NULL) { 5434 assert(p != NULL, "failed to get current directory"); 5435 return 0; 5436 } 5437 5438 return strlen(buffer); 5439} 5440 5441#ifdef JAVASE_EMBEDDED 5442// 5443// A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory. 5444// 5445MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL; 5446 5447// ctor 5448// 5449MemNotifyThread::MemNotifyThread(int fd): Thread() { 5450 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread"); 5451 _fd = fd; 5452 5453 if (os::create_thread(this, os::os_thread)) { 5454 _memnotify_thread = this; 5455 os::set_priority(this, NearMaxPriority); 5456 os::start_thread(this); 5457 } 5458} 5459 5460// Where all the work gets done 5461// 5462void MemNotifyThread::run() { 5463 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread"); 5464 5465 // Set up the select arguments 5466 fd_set rfds; 5467 if (_fd != -1) { 5468 FD_ZERO(&rfds); 5469 FD_SET(_fd, &rfds); 5470 } 5471 5472 // Now wait for the mem_notify device to wake up 5473 while (1) { 5474 // Wait for the mem_notify device to signal us.. 5475 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL); 5476 if (rc == -1) { 5477 perror("select!\n"); 5478 break; 5479 } else if (rc) { 5480 //ssize_t free_before = os::available_memory(); 5481 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024); 5482 5483 // The kernel is telling us there is not much memory left... 5484 // try to do something about that 5485 5486 // If we are not already in a GC, try one. 5487 if (!Universe::heap()->is_gc_active()) { 5488 Universe::heap()->collect(GCCause::_allocation_failure); 5489 5490 //ssize_t free_after = os::available_memory(); 5491 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024); 5492 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024); 5493 } 5494 // We might want to do something like the following if we find the GC's are not helping... 5495 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true); 5496 } 5497 } 5498} 5499 5500// 5501// See if the /dev/mem_notify device exists, and if so, start a thread to monitor it. 5502// 5503void MemNotifyThread::start() { 5504 int fd; 5505 fd = open ("/dev/mem_notify", O_RDONLY, 0); 5506 if (fd < 0) { 5507 return; 5508 } 5509 5510 if (memnotify_thread() == NULL) { 5511 new MemNotifyThread(fd); 5512 } 5513} 5514#endif // JAVASE_EMBEDDED 5515