os_linux.cpp revision 3205:cf956638b844
1/* 2 * Copyright (c) 1999, 2012, 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 "interpreter/interpreter.hpp" 33#include "jvm_linux.h" 34#include "memory/allocation.inline.hpp" 35#include "memory/filemap.hpp" 36#include "mutex_linux.inline.hpp" 37#include "oops/oop.inline.hpp" 38#include "os_share_linux.hpp" 39#include "prims/jniFastGetField.hpp" 40#include "prims/jvm.h" 41#include "prims/jvm_misc.hpp" 42#include "runtime/arguments.hpp" 43#include "runtime/extendedPC.hpp" 44#include "runtime/globals.hpp" 45#include "runtime/interfaceSupport.hpp" 46#include "runtime/java.hpp" 47#include "runtime/javaCalls.hpp" 48#include "runtime/mutexLocker.hpp" 49#include "runtime/objectMonitor.hpp" 50#include "runtime/osThread.hpp" 51#include "runtime/perfMemory.hpp" 52#include "runtime/sharedRuntime.hpp" 53#include "runtime/statSampler.hpp" 54#include "runtime/stubRoutines.hpp" 55#include "runtime/threadCritical.hpp" 56#include "runtime/timer.hpp" 57#include "services/attachListener.hpp" 58#include "services/runtimeService.hpp" 59#include "thread_linux.inline.hpp" 60#include "utilities/decoder.hpp" 61#include "utilities/defaultStream.hpp" 62#include "utilities/events.hpp" 63#include "utilities/growableArray.hpp" 64#include "utilities/vmError.hpp" 65#ifdef TARGET_ARCH_x86 66# include "assembler_x86.inline.hpp" 67# include "nativeInst_x86.hpp" 68#endif 69#ifdef TARGET_ARCH_sparc 70# include "assembler_sparc.inline.hpp" 71# include "nativeInst_sparc.hpp" 72#endif 73#ifdef TARGET_ARCH_zero 74# include "assembler_zero.inline.hpp" 75# include "nativeInst_zero.hpp" 76#endif 77#ifdef TARGET_ARCH_arm 78# include "assembler_arm.inline.hpp" 79# include "nativeInst_arm.hpp" 80#endif 81#ifdef TARGET_ARCH_ppc 82# include "assembler_ppc.inline.hpp" 83# include "nativeInst_ppc.hpp" 84#endif 85#ifdef COMPILER1 86#include "c1/c1_Runtime1.hpp" 87#endif 88#ifdef COMPILER2 89#include "opto/runtime.hpp" 90#endif 91 92// put OS-includes here 93# include <sys/types.h> 94# include <sys/mman.h> 95# include <sys/stat.h> 96# include <sys/select.h> 97# include <pthread.h> 98# include <signal.h> 99# include <errno.h> 100# include <dlfcn.h> 101# include <stdio.h> 102# include <unistd.h> 103# include <sys/resource.h> 104# include <pthread.h> 105# include <sys/stat.h> 106# include <sys/time.h> 107# include <sys/times.h> 108# include <sys/utsname.h> 109# include <sys/socket.h> 110# include <sys/wait.h> 111# include <pwd.h> 112# include <poll.h> 113# include <semaphore.h> 114# include <fcntl.h> 115# include <string.h> 116# include <syscall.h> 117# include <sys/sysinfo.h> 118# include <gnu/libc-version.h> 119# include <sys/ipc.h> 120# include <sys/shm.h> 121# include <link.h> 122# include <stdint.h> 123# include <inttypes.h> 124# include <sys/ioctl.h> 125 126#define MAX_PATH (2 * K) 127 128// for timer info max values which include all bits 129#define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 130 131#define LARGEPAGES_BIT (1 << 6) 132//////////////////////////////////////////////////////////////////////////////// 133// global variables 134julong os::Linux::_physical_memory = 0; 135 136address os::Linux::_initial_thread_stack_bottom = NULL; 137uintptr_t os::Linux::_initial_thread_stack_size = 0; 138 139int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 140int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 141Mutex* os::Linux::_createThread_lock = NULL; 142pthread_t os::Linux::_main_thread; 143int os::Linux::_page_size = -1; 144bool os::Linux::_is_floating_stack = false; 145bool os::Linux::_is_NPTL = false; 146bool os::Linux::_supports_fast_thread_cpu_time = false; 147const char * os::Linux::_glibc_version = NULL; 148const char * os::Linux::_libpthread_version = NULL; 149 150static jlong initial_time_count=0; 151 152static int clock_tics_per_sec = 100; 153 154// For diagnostics to print a message once. see run_periodic_checks 155static sigset_t check_signal_done; 156static bool check_signals = true;; 157 158static pid_t _initial_pid = 0; 159 160/* Signal number used to suspend/resume a thread */ 161 162/* do not use any signal number less than SIGSEGV, see 4355769 */ 163static int SR_signum = SIGUSR2; 164sigset_t SR_sigset; 165 166/* Used to protect dlsym() calls */ 167static pthread_mutex_t dl_mutex; 168 169#ifdef JAVASE_EMBEDDED 170class MemNotifyThread: public Thread { 171 friend class VMStructs; 172 public: 173 virtual void run(); 174 175 private: 176 static MemNotifyThread* _memnotify_thread; 177 int _fd; 178 179 public: 180 181 // Constructor 182 MemNotifyThread(int fd); 183 184 // Tester 185 bool is_memnotify_thread() const { return true; } 186 187 // Printing 188 char* name() const { return (char*)"Linux MemNotify Thread"; } 189 190 // Returns the single instance of the MemNotifyThread 191 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; } 192 193 // Create and start the single instance of MemNotifyThread 194 static void start(); 195}; 196#endif // JAVASE_EMBEDDED 197 198// utility functions 199 200static int SR_initialize(); 201static int SR_finalize(); 202 203julong os::available_memory() { 204 return Linux::available_memory(); 205} 206 207julong os::Linux::available_memory() { 208 // values in struct sysinfo are "unsigned long" 209 struct sysinfo si; 210 sysinfo(&si); 211 212 return (julong)si.freeram * si.mem_unit; 213} 214 215julong os::physical_memory() { 216 return Linux::physical_memory(); 217} 218 219julong os::allocatable_physical_memory(julong size) { 220#ifdef _LP64 221 return size; 222#else 223 julong result = MIN2(size, (julong)3800*M); 224 if (!is_allocatable(result)) { 225 // See comments under solaris for alignment considerations 226 julong reasonable_size = (julong)2*G - 2 * os::vm_page_size(); 227 result = MIN2(size, reasonable_size); 228 } 229 return result; 230#endif // _LP64 231} 232 233//////////////////////////////////////////////////////////////////////////////// 234// environment support 235 236bool os::getenv(const char* name, char* buf, int len) { 237 const char* val = ::getenv(name); 238 if (val != NULL && strlen(val) < (size_t)len) { 239 strcpy(buf, val); 240 return true; 241 } 242 if (len > 0) buf[0] = 0; // return a null string 243 return false; 244} 245 246 247// Return true if user is running as root. 248 249bool os::have_special_privileges() { 250 static bool init = false; 251 static bool privileges = false; 252 if (!init) { 253 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 254 init = true; 255 } 256 return privileges; 257} 258 259 260#ifndef SYS_gettid 261// i386: 224, ia64: 1105, amd64: 186, sparc 143 262#ifdef __ia64__ 263#define SYS_gettid 1105 264#elif __i386__ 265#define SYS_gettid 224 266#elif __amd64__ 267#define SYS_gettid 186 268#elif __sparc__ 269#define SYS_gettid 143 270#else 271#error define gettid for the arch 272#endif 273#endif 274 275// Cpu architecture string 276#if defined(ZERO) 277static char cpu_arch[] = ZERO_LIBARCH; 278#elif defined(IA64) 279static char cpu_arch[] = "ia64"; 280#elif defined(IA32) 281static char cpu_arch[] = "i386"; 282#elif defined(AMD64) 283static char cpu_arch[] = "amd64"; 284#elif defined(ARM) 285static char cpu_arch[] = "arm"; 286#elif defined(PPC) 287static char cpu_arch[] = "ppc"; 288#elif defined(SPARC) 289# ifdef _LP64 290static char cpu_arch[] = "sparcv9"; 291# else 292static char cpu_arch[] = "sparc"; 293# endif 294#else 295#error Add appropriate cpu_arch setting 296#endif 297 298 299// pid_t gettid() 300// 301// Returns the kernel thread id of the currently running thread. Kernel 302// thread id is used to access /proc. 303// 304// (Note that getpid() on LinuxThreads returns kernel thread id too; but 305// on NPTL, it returns the same pid for all threads, as required by POSIX.) 306// 307pid_t os::Linux::gettid() { 308 int rslt = syscall(SYS_gettid); 309 if (rslt == -1) { 310 // old kernel, no NPTL support 311 return getpid(); 312 } else { 313 return (pid_t)rslt; 314 } 315} 316 317// Most versions of linux have a bug where the number of processors are 318// determined by looking at the /proc file system. In a chroot environment, 319// the system call returns 1. This causes the VM to act as if it is 320// a single processor and elide locking (see is_MP() call). 321static bool unsafe_chroot_detected = false; 322static const char *unstable_chroot_error = "/proc file system not found.\n" 323 "Java may be unstable running multithreaded in a chroot " 324 "environment on Linux when /proc filesystem is not mounted."; 325 326void os::Linux::initialize_system_info() { 327 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 328 if (processor_count() == 1) { 329 pid_t pid = os::Linux::gettid(); 330 char fname[32]; 331 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 332 FILE *fp = fopen(fname, "r"); 333 if (fp == NULL) { 334 unsafe_chroot_detected = true; 335 } else { 336 fclose(fp); 337 } 338 } 339 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 340 assert(processor_count() > 0, "linux error"); 341} 342 343void os::init_system_properties_values() { 344// char arch[12]; 345// sysinfo(SI_ARCHITECTURE, arch, sizeof(arch)); 346 347 // The next steps are taken in the product version: 348 // 349 // Obtain the JAVA_HOME value from the location of libjvm[_g].so. 350 // This library should be located at: 351 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm[_g].so. 352 // 353 // If "/jre/lib/" appears at the right place in the path, then we 354 // assume libjvm[_g].so is installed in a JDK and we use this path. 355 // 356 // Otherwise exit with message: "Could not create the Java virtual machine." 357 // 358 // The following extra steps are taken in the debugging version: 359 // 360 // If "/jre/lib/" does NOT appear at the right place in the path 361 // instead of exit check for $JAVA_HOME environment variable. 362 // 363 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 364 // then we append a fake suffix "hotspot/libjvm[_g].so" to this path so 365 // it looks like libjvm[_g].so is installed there 366 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm[_g].so. 367 // 368 // Otherwise exit. 369 // 370 // Important note: if the location of libjvm.so changes this 371 // code needs to be changed accordingly. 372 373 // The next few definitions allow the code to be verbatim: 374#define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n)) 375#define getenv(n) ::getenv(n) 376 377/* 378 * See ld(1): 379 * The linker uses the following search paths to locate required 380 * shared libraries: 381 * 1: ... 382 * ... 383 * 7: The default directories, normally /lib and /usr/lib. 384 */ 385#if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 386#define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 387#else 388#define DEFAULT_LIBPATH "/lib:/usr/lib" 389#endif 390 391#define EXTENSIONS_DIR "/lib/ext" 392#define ENDORSED_DIR "/lib/endorsed" 393#define REG_DIR "/usr/java/packages" 394 395 { 396 /* sysclasspath, java_home, dll_dir */ 397 { 398 char *home_path; 399 char *dll_path; 400 char *pslash; 401 char buf[MAXPATHLEN]; 402 os::jvm_path(buf, sizeof(buf)); 403 404 // Found the full path to libjvm.so. 405 // Now cut the path to <java_home>/jre if we can. 406 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */ 407 pslash = strrchr(buf, '/'); 408 if (pslash != NULL) 409 *pslash = '\0'; /* get rid of /{client|server|hotspot} */ 410 dll_path = malloc(strlen(buf) + 1); 411 if (dll_path == NULL) 412 return; 413 strcpy(dll_path, buf); 414 Arguments::set_dll_dir(dll_path); 415 416 if (pslash != NULL) { 417 pslash = strrchr(buf, '/'); 418 if (pslash != NULL) { 419 *pslash = '\0'; /* get rid of /<arch> */ 420 pslash = strrchr(buf, '/'); 421 if (pslash != NULL) 422 *pslash = '\0'; /* get rid of /lib */ 423 } 424 } 425 426 home_path = malloc(strlen(buf) + 1); 427 if (home_path == NULL) 428 return; 429 strcpy(home_path, buf); 430 Arguments::set_java_home(home_path); 431 432 if (!set_boot_path('/', ':')) 433 return; 434 } 435 436 /* 437 * Where to look for native libraries 438 * 439 * Note: Due to a legacy implementation, most of the library path 440 * is set in the launcher. This was to accomodate linking restrictions 441 * on legacy Linux implementations (which are no longer supported). 442 * Eventually, all the library path setting will be done here. 443 * 444 * However, to prevent the proliferation of improperly built native 445 * libraries, the new path component /usr/java/packages is added here. 446 * Eventually, all the library path setting will be done here. 447 */ 448 { 449 char *ld_library_path; 450 451 /* 452 * Construct the invariant part of ld_library_path. Note that the 453 * space for the colon and the trailing null are provided by the 454 * nulls included by the sizeof operator (so actually we allocate 455 * a byte more than necessary). 456 */ 457 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") + 458 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH)); 459 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch); 460 461 /* 462 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It 463 * should always exist (until the legacy problem cited above is 464 * addressed). 465 */ 466 char *v = getenv("LD_LIBRARY_PATH"); 467 if (v != NULL) { 468 char *t = ld_library_path; 469 /* That's +1 for the colon and +1 for the trailing '\0' */ 470 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1); 471 sprintf(ld_library_path, "%s:%s", v, t); 472 } 473 Arguments::set_library_path(ld_library_path); 474 } 475 476 /* 477 * Extensions directories. 478 * 479 * Note that the space for the colon and the trailing null are provided 480 * by the nulls included by the sizeof operator (so actually one byte more 481 * than necessary is allocated). 482 */ 483 { 484 char *buf = malloc(strlen(Arguments::get_java_home()) + 485 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR)); 486 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR, 487 Arguments::get_java_home()); 488 Arguments::set_ext_dirs(buf); 489 } 490 491 /* Endorsed standards default directory. */ 492 { 493 char * buf; 494 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR)); 495 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 496 Arguments::set_endorsed_dirs(buf); 497 } 498 } 499 500#undef malloc 501#undef getenv 502#undef EXTENSIONS_DIR 503#undef ENDORSED_DIR 504 505 // Done 506 return; 507} 508 509//////////////////////////////////////////////////////////////////////////////// 510// breakpoint support 511 512void os::breakpoint() { 513 BREAKPOINT; 514} 515 516extern "C" void breakpoint() { 517 // use debugger to set breakpoint here 518} 519 520//////////////////////////////////////////////////////////////////////////////// 521// signal support 522 523debug_only(static bool signal_sets_initialized = false); 524static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 525 526bool os::Linux::is_sig_ignored(int sig) { 527 struct sigaction oact; 528 sigaction(sig, (struct sigaction*)NULL, &oact); 529 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 530 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 531 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 532 return true; 533 else 534 return false; 535} 536 537void os::Linux::signal_sets_init() { 538 // Should also have an assertion stating we are still single-threaded. 539 assert(!signal_sets_initialized, "Already initialized"); 540 // Fill in signals that are necessarily unblocked for all threads in 541 // the VM. Currently, we unblock the following signals: 542 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 543 // by -Xrs (=ReduceSignalUsage)); 544 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 545 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 546 // the dispositions or masks wrt these signals. 547 // Programs embedding the VM that want to use the above signals for their 548 // own purposes must, at this time, use the "-Xrs" option to prevent 549 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 550 // (See bug 4345157, and other related bugs). 551 // In reality, though, unblocking these signals is really a nop, since 552 // these signals are not blocked by default. 553 sigemptyset(&unblocked_sigs); 554 sigemptyset(&allowdebug_blocked_sigs); 555 sigaddset(&unblocked_sigs, SIGILL); 556 sigaddset(&unblocked_sigs, SIGSEGV); 557 sigaddset(&unblocked_sigs, SIGBUS); 558 sigaddset(&unblocked_sigs, SIGFPE); 559 sigaddset(&unblocked_sigs, SR_signum); 560 561 if (!ReduceSignalUsage) { 562 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 563 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 564 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 565 } 566 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 567 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 568 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 569 } 570 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 571 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 572 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 573 } 574 } 575 // Fill in signals that are blocked by all but the VM thread. 576 sigemptyset(&vm_sigs); 577 if (!ReduceSignalUsage) 578 sigaddset(&vm_sigs, BREAK_SIGNAL); 579 debug_only(signal_sets_initialized = true); 580 581} 582 583// These are signals that are unblocked while a thread is running Java. 584// (For some reason, they get blocked by default.) 585sigset_t* os::Linux::unblocked_signals() { 586 assert(signal_sets_initialized, "Not initialized"); 587 return &unblocked_sigs; 588} 589 590// These are the signals that are blocked while a (non-VM) thread is 591// running Java. Only the VM thread handles these signals. 592sigset_t* os::Linux::vm_signals() { 593 assert(signal_sets_initialized, "Not initialized"); 594 return &vm_sigs; 595} 596 597// These are signals that are blocked during cond_wait to allow debugger in 598sigset_t* os::Linux::allowdebug_blocked_signals() { 599 assert(signal_sets_initialized, "Not initialized"); 600 return &allowdebug_blocked_sigs; 601} 602 603void os::Linux::hotspot_sigmask(Thread* thread) { 604 605 //Save caller's signal mask before setting VM signal mask 606 sigset_t caller_sigmask; 607 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 608 609 OSThread* osthread = thread->osthread(); 610 osthread->set_caller_sigmask(caller_sigmask); 611 612 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 613 614 if (!ReduceSignalUsage) { 615 if (thread->is_VM_thread()) { 616 // Only the VM thread handles BREAK_SIGNAL ... 617 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 618 } else { 619 // ... all other threads block BREAK_SIGNAL 620 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 621 } 622 } 623} 624 625////////////////////////////////////////////////////////////////////////////// 626// detecting pthread library 627 628void os::Linux::libpthread_init() { 629 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 630 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 631 // generic name for earlier versions. 632 // Define macros here so we can build HotSpot on old systems. 633# ifndef _CS_GNU_LIBC_VERSION 634# define _CS_GNU_LIBC_VERSION 2 635# endif 636# ifndef _CS_GNU_LIBPTHREAD_VERSION 637# define _CS_GNU_LIBPTHREAD_VERSION 3 638# endif 639 640 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 641 if (n > 0) { 642 char *str = (char *)malloc(n); 643 confstr(_CS_GNU_LIBC_VERSION, str, n); 644 os::Linux::set_glibc_version(str); 645 } else { 646 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 647 static char _gnu_libc_version[32]; 648 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 649 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 650 os::Linux::set_glibc_version(_gnu_libc_version); 651 } 652 653 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 654 if (n > 0) { 655 char *str = (char *)malloc(n); 656 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 657 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 658 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 659 // is the case. LinuxThreads has a hard limit on max number of threads. 660 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 661 // On the other hand, NPTL does not have such a limit, sysconf() 662 // will return -1 and errno is not changed. Check if it is really NPTL. 663 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 664 strstr(str, "NPTL") && 665 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 666 free(str); 667 os::Linux::set_libpthread_version("linuxthreads"); 668 } else { 669 os::Linux::set_libpthread_version(str); 670 } 671 } else { 672 // glibc before 2.3.2 only has LinuxThreads. 673 os::Linux::set_libpthread_version("linuxthreads"); 674 } 675 676 if (strstr(libpthread_version(), "NPTL")) { 677 os::Linux::set_is_NPTL(); 678 } else { 679 os::Linux::set_is_LinuxThreads(); 680 } 681 682 // LinuxThreads have two flavors: floating-stack mode, which allows variable 683 // stack size; and fixed-stack mode. NPTL is always floating-stack. 684 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 685 os::Linux::set_is_floating_stack(); 686 } 687} 688 689///////////////////////////////////////////////////////////////////////////// 690// thread stack 691 692// Force Linux kernel to expand current thread stack. If "bottom" is close 693// to the stack guard, caller should block all signals. 694// 695// MAP_GROWSDOWN: 696// A special mmap() flag that is used to implement thread stacks. It tells 697// kernel that the memory region should extend downwards when needed. This 698// allows early versions of LinuxThreads to only mmap the first few pages 699// when creating a new thread. Linux kernel will automatically expand thread 700// stack as needed (on page faults). 701// 702// However, because the memory region of a MAP_GROWSDOWN stack can grow on 703// demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 704// region, it's hard to tell if the fault is due to a legitimate stack 705// access or because of reading/writing non-exist memory (e.g. buffer 706// overrun). As a rule, if the fault happens below current stack pointer, 707// Linux kernel does not expand stack, instead a SIGSEGV is sent to the 708// application (see Linux kernel fault.c). 709// 710// This Linux feature can cause SIGSEGV when VM bangs thread stack for 711// stack overflow detection. 712// 713// Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 714// not use this flag. However, the stack of initial thread is not created 715// by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 716// unlikely) that user code can create a thread with MAP_GROWSDOWN stack 717// and then attach the thread to JVM. 718// 719// To get around the problem and allow stack banging on Linux, we need to 720// manually expand thread stack after receiving the SIGSEGV. 721// 722// There are two ways to expand thread stack to address "bottom", we used 723// both of them in JVM before 1.5: 724// 1. adjust stack pointer first so that it is below "bottom", and then 725// touch "bottom" 726// 2. mmap() the page in question 727// 728// Now alternate signal stack is gone, it's harder to use 2. For instance, 729// if current sp is already near the lower end of page 101, and we need to 730// call mmap() to map page 100, it is possible that part of the mmap() frame 731// will be placed in page 100. When page 100 is mapped, it is zero-filled. 732// That will destroy the mmap() frame and cause VM to crash. 733// 734// The following code works by adjusting sp first, then accessing the "bottom" 735// page to force a page fault. Linux kernel will then automatically expand the 736// stack mapping. 737// 738// _expand_stack_to() assumes its frame size is less than page size, which 739// should always be true if the function is not inlined. 740 741#if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 742#define NOINLINE 743#else 744#define NOINLINE __attribute__ ((noinline)) 745#endif 746 747static void _expand_stack_to(address bottom) NOINLINE; 748 749static void _expand_stack_to(address bottom) { 750 address sp; 751 size_t size; 752 volatile char *p; 753 754 // Adjust bottom to point to the largest address within the same page, it 755 // gives us a one-page buffer if alloca() allocates slightly more memory. 756 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 757 bottom += os::Linux::page_size() - 1; 758 759 // sp might be slightly above current stack pointer; if that's the case, we 760 // will alloca() a little more space than necessary, which is OK. Don't use 761 // os::current_stack_pointer(), as its result can be slightly below current 762 // stack pointer, causing us to not alloca enough to reach "bottom". 763 sp = (address)&sp; 764 765 if (sp > bottom) { 766 size = sp - bottom; 767 p = (volatile char *)alloca(size); 768 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 769 p[0] = '\0'; 770 } 771} 772 773bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 774 assert(t!=NULL, "just checking"); 775 assert(t->osthread()->expanding_stack(), "expand should be set"); 776 assert(t->stack_base() != NULL, "stack_base was not initialized"); 777 778 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 779 sigset_t mask_all, old_sigset; 780 sigfillset(&mask_all); 781 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 782 _expand_stack_to(addr); 783 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 784 return true; 785 } 786 return false; 787} 788 789////////////////////////////////////////////////////////////////////////////// 790// create new thread 791 792static address highest_vm_reserved_address(); 793 794// check if it's safe to start a new thread 795static bool _thread_safety_check(Thread* thread) { 796 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 797 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 798 // Heap is mmap'ed at lower end of memory space. Thread stacks are 799 // allocated (MAP_FIXED) from high address space. Every thread stack 800 // occupies a fixed size slot (usually 2Mbytes, but user can change 801 // it to other values if they rebuild LinuxThreads). 802 // 803 // Problem with MAP_FIXED is that mmap() can still succeed even part of 804 // the memory region has already been mmap'ed. That means if we have too 805 // many threads and/or very large heap, eventually thread stack will 806 // collide with heap. 807 // 808 // Here we try to prevent heap/stack collision by comparing current 809 // stack bottom with the highest address that has been mmap'ed by JVM 810 // plus a safety margin for memory maps created by native code. 811 // 812 // This feature can be disabled by setting ThreadSafetyMargin to 0 813 // 814 if (ThreadSafetyMargin > 0) { 815 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 816 817 // not safe if our stack extends below the safety margin 818 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 819 } else { 820 return true; 821 } 822 } else { 823 // Floating stack LinuxThreads or NPTL: 824 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 825 // there's not enough space left, pthread_create() will fail. If we come 826 // here, that means enough space has been reserved for stack. 827 return true; 828 } 829} 830 831// Thread start routine for all newly created threads 832static void *java_start(Thread *thread) { 833 // Try to randomize the cache line index of hot stack frames. 834 // This helps when threads of the same stack traces evict each other's 835 // cache lines. The threads can be either from the same JVM instance, or 836 // from different JVM instances. The benefit is especially true for 837 // processors with hyperthreading technology. 838 static int counter = 0; 839 int pid = os::current_process_id(); 840 alloca(((pid ^ counter++) & 7) * 128); 841 842 ThreadLocalStorage::set_thread(thread); 843 844 OSThread* osthread = thread->osthread(); 845 Monitor* sync = osthread->startThread_lock(); 846 847 // non floating stack LinuxThreads needs extra check, see above 848 if (!_thread_safety_check(thread)) { 849 // notify parent thread 850 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 851 osthread->set_state(ZOMBIE); 852 sync->notify_all(); 853 return NULL; 854 } 855 856 // thread_id is kernel thread id (similar to Solaris LWP id) 857 osthread->set_thread_id(os::Linux::gettid()); 858 859 if (UseNUMA) { 860 int lgrp_id = os::numa_get_group_id(); 861 if (lgrp_id != -1) { 862 thread->set_lgrp_id(lgrp_id); 863 } 864 } 865 // initialize signal mask for this thread 866 os::Linux::hotspot_sigmask(thread); 867 868 // initialize floating point control register 869 os::Linux::init_thread_fpu_state(); 870 871 // handshaking with parent thread 872 { 873 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 874 875 // notify parent thread 876 osthread->set_state(INITIALIZED); 877 sync->notify_all(); 878 879 // wait until os::start_thread() 880 while (osthread->get_state() == INITIALIZED) { 881 sync->wait(Mutex::_no_safepoint_check_flag); 882 } 883 } 884 885 // call one more level start routine 886 thread->run(); 887 888 return 0; 889} 890 891bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 892 assert(thread->osthread() == NULL, "caller responsible"); 893 894 // Allocate the OSThread object 895 OSThread* osthread = new OSThread(NULL, NULL); 896 if (osthread == NULL) { 897 return false; 898 } 899 900 // set the correct thread state 901 osthread->set_thread_type(thr_type); 902 903 // Initial state is ALLOCATED but not INITIALIZED 904 osthread->set_state(ALLOCATED); 905 906 thread->set_osthread(osthread); 907 908 // init thread attributes 909 pthread_attr_t attr; 910 pthread_attr_init(&attr); 911 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 912 913 // stack size 914 if (os::Linux::supports_variable_stack_size()) { 915 // calculate stack size if it's not specified by caller 916 if (stack_size == 0) { 917 stack_size = os::Linux::default_stack_size(thr_type); 918 919 switch (thr_type) { 920 case os::java_thread: 921 // Java threads use ThreadStackSize which default value can be 922 // changed with the flag -Xss 923 assert (JavaThread::stack_size_at_create() > 0, "this should be set"); 924 stack_size = JavaThread::stack_size_at_create(); 925 break; 926 case os::compiler_thread: 927 if (CompilerThreadStackSize > 0) { 928 stack_size = (size_t)(CompilerThreadStackSize * K); 929 break; 930 } // else fall through: 931 // use VMThreadStackSize if CompilerThreadStackSize is not defined 932 case os::vm_thread: 933 case os::pgc_thread: 934 case os::cgc_thread: 935 case os::watcher_thread: 936 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 937 break; 938 } 939 } 940 941 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 942 pthread_attr_setstacksize(&attr, stack_size); 943 } else { 944 // let pthread_create() pick the default value. 945 } 946 947 // glibc guard page 948 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 949 950 ThreadState state; 951 952 { 953 // Serialize thread creation if we are running with fixed stack LinuxThreads 954 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 955 if (lock) { 956 os::Linux::createThread_lock()->lock_without_safepoint_check(); 957 } 958 959 pthread_t tid; 960 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 961 962 pthread_attr_destroy(&attr); 963 964 if (ret != 0) { 965 if (PrintMiscellaneous && (Verbose || WizardMode)) { 966 perror("pthread_create()"); 967 } 968 // Need to clean up stuff we've allocated so far 969 thread->set_osthread(NULL); 970 delete osthread; 971 if (lock) os::Linux::createThread_lock()->unlock(); 972 return false; 973 } 974 975 // Store pthread info into the OSThread 976 osthread->set_pthread_id(tid); 977 978 // Wait until child thread is either initialized or aborted 979 { 980 Monitor* sync_with_child = osthread->startThread_lock(); 981 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 982 while ((state = osthread->get_state()) == ALLOCATED) { 983 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 984 } 985 } 986 987 if (lock) { 988 os::Linux::createThread_lock()->unlock(); 989 } 990 } 991 992 // Aborted due to thread limit being reached 993 if (state == ZOMBIE) { 994 thread->set_osthread(NULL); 995 delete osthread; 996 return false; 997 } 998 999 // The thread is returned suspended (in state INITIALIZED), 1000 // and is started higher up in the call chain 1001 assert(state == INITIALIZED, "race condition"); 1002 return true; 1003} 1004 1005///////////////////////////////////////////////////////////////////////////// 1006// attach existing thread 1007 1008// bootstrap the main thread 1009bool os::create_main_thread(JavaThread* thread) { 1010 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 1011 return create_attached_thread(thread); 1012} 1013 1014bool os::create_attached_thread(JavaThread* thread) { 1015#ifdef ASSERT 1016 thread->verify_not_published(); 1017#endif 1018 1019 // Allocate the OSThread object 1020 OSThread* osthread = new OSThread(NULL, NULL); 1021 1022 if (osthread == NULL) { 1023 return false; 1024 } 1025 1026 // Store pthread info into the OSThread 1027 osthread->set_thread_id(os::Linux::gettid()); 1028 osthread->set_pthread_id(::pthread_self()); 1029 1030 // initialize floating point control register 1031 os::Linux::init_thread_fpu_state(); 1032 1033 // Initial thread state is RUNNABLE 1034 osthread->set_state(RUNNABLE); 1035 1036 thread->set_osthread(osthread); 1037 1038 if (UseNUMA) { 1039 int lgrp_id = os::numa_get_group_id(); 1040 if (lgrp_id != -1) { 1041 thread->set_lgrp_id(lgrp_id); 1042 } 1043 } 1044 1045 if (os::Linux::is_initial_thread()) { 1046 // If current thread is initial thread, its stack is mapped on demand, 1047 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 1048 // the entire stack region to avoid SEGV in stack banging. 1049 // It is also useful to get around the heap-stack-gap problem on SuSE 1050 // kernel (see 4821821 for details). We first expand stack to the top 1051 // of yellow zone, then enable stack yellow zone (order is significant, 1052 // enabling yellow zone first will crash JVM on SuSE Linux), so there 1053 // is no gap between the last two virtual memory regions. 1054 1055 JavaThread *jt = (JavaThread *)thread; 1056 address addr = jt->stack_yellow_zone_base(); 1057 assert(addr != NULL, "initialization problem?"); 1058 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 1059 1060 osthread->set_expanding_stack(); 1061 os::Linux::manually_expand_stack(jt, addr); 1062 osthread->clear_expanding_stack(); 1063 } 1064 1065 // initialize signal mask for this thread 1066 // and save the caller's signal mask 1067 os::Linux::hotspot_sigmask(thread); 1068 1069 return true; 1070} 1071 1072void os::pd_start_thread(Thread* thread) { 1073 OSThread * osthread = thread->osthread(); 1074 assert(osthread->get_state() != INITIALIZED, "just checking"); 1075 Monitor* sync_with_child = osthread->startThread_lock(); 1076 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 1077 sync_with_child->notify(); 1078} 1079 1080// Free Linux resources related to the OSThread 1081void os::free_thread(OSThread* osthread) { 1082 assert(osthread != NULL, "osthread not set"); 1083 1084 if (Thread::current()->osthread() == osthread) { 1085 // Restore caller's signal mask 1086 sigset_t sigmask = osthread->caller_sigmask(); 1087 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1088 } 1089 1090 delete osthread; 1091} 1092 1093////////////////////////////////////////////////////////////////////////////// 1094// thread local storage 1095 1096int os::allocate_thread_local_storage() { 1097 pthread_key_t key; 1098 int rslt = pthread_key_create(&key, NULL); 1099 assert(rslt == 0, "cannot allocate thread local storage"); 1100 return (int)key; 1101} 1102 1103// Note: This is currently not used by VM, as we don't destroy TLS key 1104// on VM exit. 1105void os::free_thread_local_storage(int index) { 1106 int rslt = pthread_key_delete((pthread_key_t)index); 1107 assert(rslt == 0, "invalid index"); 1108} 1109 1110void os::thread_local_storage_at_put(int index, void* value) { 1111 int rslt = pthread_setspecific((pthread_key_t)index, value); 1112 assert(rslt == 0, "pthread_setspecific failed"); 1113} 1114 1115extern "C" Thread* get_thread() { 1116 return ThreadLocalStorage::thread(); 1117} 1118 1119////////////////////////////////////////////////////////////////////////////// 1120// initial thread 1121 1122// Check if current thread is the initial thread, similar to Solaris thr_main. 1123bool os::Linux::is_initial_thread(void) { 1124 char dummy; 1125 // If called before init complete, thread stack bottom will be null. 1126 // Can be called if fatal error occurs before initialization. 1127 if (initial_thread_stack_bottom() == NULL) return false; 1128 assert(initial_thread_stack_bottom() != NULL && 1129 initial_thread_stack_size() != 0, 1130 "os::init did not locate initial thread's stack region"); 1131 if ((address)&dummy >= initial_thread_stack_bottom() && 1132 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1133 return true; 1134 else return false; 1135} 1136 1137// Find the virtual memory area that contains addr 1138static bool find_vma(address addr, address* vma_low, address* vma_high) { 1139 FILE *fp = fopen("/proc/self/maps", "r"); 1140 if (fp) { 1141 address low, high; 1142 while (!feof(fp)) { 1143 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1144 if (low <= addr && addr < high) { 1145 if (vma_low) *vma_low = low; 1146 if (vma_high) *vma_high = high; 1147 fclose (fp); 1148 return true; 1149 } 1150 } 1151 for (;;) { 1152 int ch = fgetc(fp); 1153 if (ch == EOF || ch == (int)'\n') break; 1154 } 1155 } 1156 fclose(fp); 1157 } 1158 return false; 1159} 1160 1161// Locate initial thread stack. This special handling of initial thread stack 1162// is needed because pthread_getattr_np() on most (all?) Linux distros returns 1163// bogus value for initial thread. 1164void os::Linux::capture_initial_stack(size_t max_size) { 1165 // stack size is the easy part, get it from RLIMIT_STACK 1166 size_t stack_size; 1167 struct rlimit rlim; 1168 getrlimit(RLIMIT_STACK, &rlim); 1169 stack_size = rlim.rlim_cur; 1170 1171 // 6308388: a bug in ld.so will relocate its own .data section to the 1172 // lower end of primordial stack; reduce ulimit -s value a little bit 1173 // so we won't install guard page on ld.so's data section. 1174 stack_size -= 2 * page_size(); 1175 1176 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1177 // 7.1, in both cases we will get 2G in return value. 1178 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1179 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1180 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1181 // in case other parts in glibc still assumes 2M max stack size. 1182 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1183#ifndef IA64 1184 if (stack_size > 2 * K * K) stack_size = 2 * K * K; 1185#else 1186 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1187 if (stack_size > 4 * K * K) stack_size = 4 * K * K; 1188#endif 1189 1190 // Try to figure out where the stack base (top) is. This is harder. 1191 // 1192 // When an application is started, glibc saves the initial stack pointer in 1193 // a global variable "__libc_stack_end", which is then used by system 1194 // libraries. __libc_stack_end should be pretty close to stack top. The 1195 // variable is available since the very early days. However, because it is 1196 // a private interface, it could disappear in the future. 1197 // 1198 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1199 // to __libc_stack_end, it is very close to stack top, but isn't the real 1200 // stack top. Note that /proc may not exist if VM is running as a chroot 1201 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1202 // /proc/<pid>/stat could change in the future (though unlikely). 1203 // 1204 // We try __libc_stack_end first. If that doesn't work, look for 1205 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1206 // as a hint, which should work well in most cases. 1207 1208 uintptr_t stack_start; 1209 1210 // try __libc_stack_end first 1211 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1212 if (p && *p) { 1213 stack_start = *p; 1214 } else { 1215 // see if we can get the start_stack field from /proc/self/stat 1216 FILE *fp; 1217 int pid; 1218 char state; 1219 int ppid; 1220 int pgrp; 1221 int session; 1222 int nr; 1223 int tpgrp; 1224 unsigned long flags; 1225 unsigned long minflt; 1226 unsigned long cminflt; 1227 unsigned long majflt; 1228 unsigned long cmajflt; 1229 unsigned long utime; 1230 unsigned long stime; 1231 long cutime; 1232 long cstime; 1233 long prio; 1234 long nice; 1235 long junk; 1236 long it_real; 1237 uintptr_t start; 1238 uintptr_t vsize; 1239 intptr_t rss; 1240 uintptr_t rsslim; 1241 uintptr_t scodes; 1242 uintptr_t ecode; 1243 int i; 1244 1245 // Figure what the primordial thread stack base is. Code is inspired 1246 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1247 // followed by command name surrounded by parentheses, state, etc. 1248 char stat[2048]; 1249 int statlen; 1250 1251 fp = fopen("/proc/self/stat", "r"); 1252 if (fp) { 1253 statlen = fread(stat, 1, 2047, fp); 1254 stat[statlen] = '\0'; 1255 fclose(fp); 1256 1257 // Skip pid and the command string. Note that we could be dealing with 1258 // weird command names, e.g. user could decide to rename java launcher 1259 // to "java 1.4.2 :)", then the stat file would look like 1260 // 1234 (java 1.4.2 :)) R ... ... 1261 // We don't really need to know the command string, just find the last 1262 // occurrence of ")" and then start parsing from there. See bug 4726580. 1263 char * s = strrchr(stat, ')'); 1264 1265 i = 0; 1266 if (s) { 1267 // Skip blank chars 1268 do s++; while (isspace(*s)); 1269 1270#define _UFM UINTX_FORMAT 1271#define _DFM INTX_FORMAT 1272 1273 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1274 /* 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 */ 1275 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, 1276 &state, /* 3 %c */ 1277 &ppid, /* 4 %d */ 1278 &pgrp, /* 5 %d */ 1279 &session, /* 6 %d */ 1280 &nr, /* 7 %d */ 1281 &tpgrp, /* 8 %d */ 1282 &flags, /* 9 %lu */ 1283 &minflt, /* 10 %lu */ 1284 &cminflt, /* 11 %lu */ 1285 &majflt, /* 12 %lu */ 1286 &cmajflt, /* 13 %lu */ 1287 &utime, /* 14 %lu */ 1288 &stime, /* 15 %lu */ 1289 &cutime, /* 16 %ld */ 1290 &cstime, /* 17 %ld */ 1291 &prio, /* 18 %ld */ 1292 &nice, /* 19 %ld */ 1293 &junk, /* 20 %ld */ 1294 &it_real, /* 21 %ld */ 1295 &start, /* 22 UINTX_FORMAT */ 1296 &vsize, /* 23 UINTX_FORMAT */ 1297 &rss, /* 24 INTX_FORMAT */ 1298 &rsslim, /* 25 UINTX_FORMAT */ 1299 &scodes, /* 26 UINTX_FORMAT */ 1300 &ecode, /* 27 UINTX_FORMAT */ 1301 &stack_start); /* 28 UINTX_FORMAT */ 1302 } 1303 1304#undef _UFM 1305#undef _DFM 1306 1307 if (i != 28 - 2) { 1308 assert(false, "Bad conversion from /proc/self/stat"); 1309 // product mode - assume we are the initial thread, good luck in the 1310 // embedded case. 1311 warning("Can't detect initial thread stack location - bad conversion"); 1312 stack_start = (uintptr_t) &rlim; 1313 } 1314 } else { 1315 // For some reason we can't open /proc/self/stat (for example, running on 1316 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1317 // most cases, so don't abort: 1318 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1319 stack_start = (uintptr_t) &rlim; 1320 } 1321 } 1322 1323 // Now we have a pointer (stack_start) very close to the stack top, the 1324 // next thing to do is to figure out the exact location of stack top. We 1325 // can find out the virtual memory area that contains stack_start by 1326 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1327 // and its upper limit is the real stack top. (again, this would fail if 1328 // running inside chroot, because /proc may not exist.) 1329 1330 uintptr_t stack_top; 1331 address low, high; 1332 if (find_vma((address)stack_start, &low, &high)) { 1333 // success, "high" is the true stack top. (ignore "low", because initial 1334 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1335 stack_top = (uintptr_t)high; 1336 } else { 1337 // failed, likely because /proc/self/maps does not exist 1338 warning("Can't detect initial thread stack location - find_vma failed"); 1339 // best effort: stack_start is normally within a few pages below the real 1340 // stack top, use it as stack top, and reduce stack size so we won't put 1341 // guard page outside stack. 1342 stack_top = stack_start; 1343 stack_size -= 16 * page_size(); 1344 } 1345 1346 // stack_top could be partially down the page so align it 1347 stack_top = align_size_up(stack_top, page_size()); 1348 1349 if (max_size && stack_size > max_size) { 1350 _initial_thread_stack_size = max_size; 1351 } else { 1352 _initial_thread_stack_size = stack_size; 1353 } 1354 1355 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1356 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1357} 1358 1359//////////////////////////////////////////////////////////////////////////////// 1360// time support 1361 1362// Time since start-up in seconds to a fine granularity. 1363// Used by VMSelfDestructTimer and the MemProfiler. 1364double os::elapsedTime() { 1365 1366 return (double)(os::elapsed_counter()) * 0.000001; 1367} 1368 1369jlong os::elapsed_counter() { 1370 timeval time; 1371 int status = gettimeofday(&time, NULL); 1372 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count; 1373} 1374 1375jlong os::elapsed_frequency() { 1376 return (1000 * 1000); 1377} 1378 1379// For now, we say that linux does not support vtime. I have no idea 1380// whether it can actually be made to (DLD, 9/13/05). 1381 1382bool os::supports_vtime() { return false; } 1383bool os::enable_vtime() { return false; } 1384bool os::vtime_enabled() { return false; } 1385double os::elapsedVTime() { 1386 // better than nothing, but not much 1387 return elapsedTime(); 1388} 1389 1390jlong os::javaTimeMillis() { 1391 timeval time; 1392 int status = gettimeofday(&time, NULL); 1393 assert(status != -1, "linux error"); 1394 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1395} 1396 1397#ifndef CLOCK_MONOTONIC 1398#define CLOCK_MONOTONIC (1) 1399#endif 1400 1401void os::Linux::clock_init() { 1402 // we do dlopen's in this particular order due to bug in linux 1403 // dynamical loader (see 6348968) leading to crash on exit 1404 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1405 if (handle == NULL) { 1406 handle = dlopen("librt.so", RTLD_LAZY); 1407 } 1408 1409 if (handle) { 1410 int (*clock_getres_func)(clockid_t, struct timespec*) = 1411 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1412 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1413 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1414 if (clock_getres_func && clock_gettime_func) { 1415 // See if monotonic clock is supported by the kernel. Note that some 1416 // early implementations simply return kernel jiffies (updated every 1417 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1418 // for nano time (though the monotonic property is still nice to have). 1419 // It's fixed in newer kernels, however clock_getres() still returns 1420 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1421 // resolution for now. Hopefully as people move to new kernels, this 1422 // won't be a problem. 1423 struct timespec res; 1424 struct timespec tp; 1425 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1426 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1427 // yes, monotonic clock is supported 1428 _clock_gettime = clock_gettime_func; 1429 } else { 1430 // close librt if there is no monotonic clock 1431 dlclose(handle); 1432 } 1433 } 1434 } 1435} 1436 1437#ifndef SYS_clock_getres 1438 1439#if defined(IA32) || defined(AMD64) 1440#define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1441#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1442#else 1443#warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1444#define sys_clock_getres(x,y) -1 1445#endif 1446 1447#else 1448#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1449#endif 1450 1451void os::Linux::fast_thread_clock_init() { 1452 if (!UseLinuxPosixThreadCPUClocks) { 1453 return; 1454 } 1455 clockid_t clockid; 1456 struct timespec tp; 1457 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1458 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1459 1460 // Switch to using fast clocks for thread cpu time if 1461 // the sys_clock_getres() returns 0 error code. 1462 // Note, that some kernels may support the current thread 1463 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1464 // returned by the pthread_getcpuclockid(). 1465 // If the fast Posix clocks are supported then the sys_clock_getres() 1466 // must return at least tp.tv_sec == 0 which means a resolution 1467 // better than 1 sec. This is extra check for reliability. 1468 1469 if(pthread_getcpuclockid_func && 1470 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1471 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1472 1473 _supports_fast_thread_cpu_time = true; 1474 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1475 } 1476} 1477 1478jlong os::javaTimeNanos() { 1479 if (Linux::supports_monotonic_clock()) { 1480 struct timespec tp; 1481 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1482 assert(status == 0, "gettime error"); 1483 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1484 return result; 1485 } else { 1486 timeval time; 1487 int status = gettimeofday(&time, NULL); 1488 assert(status != -1, "linux error"); 1489 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1490 return 1000 * usecs; 1491 } 1492} 1493 1494void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1495 if (Linux::supports_monotonic_clock()) { 1496 info_ptr->max_value = ALL_64_BITS; 1497 1498 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1499 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1500 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1501 } else { 1502 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1503 info_ptr->max_value = ALL_64_BITS; 1504 1505 // gettimeofday is a real time clock so it skips 1506 info_ptr->may_skip_backward = true; 1507 info_ptr->may_skip_forward = true; 1508 } 1509 1510 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1511} 1512 1513// Return the real, user, and system times in seconds from an 1514// arbitrary fixed point in the past. 1515bool os::getTimesSecs(double* process_real_time, 1516 double* process_user_time, 1517 double* process_system_time) { 1518 struct tms ticks; 1519 clock_t real_ticks = times(&ticks); 1520 1521 if (real_ticks == (clock_t) (-1)) { 1522 return false; 1523 } else { 1524 double ticks_per_second = (double) clock_tics_per_sec; 1525 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1526 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1527 *process_real_time = ((double) real_ticks) / ticks_per_second; 1528 1529 return true; 1530 } 1531} 1532 1533 1534char * os::local_time_string(char *buf, size_t buflen) { 1535 struct tm t; 1536 time_t long_time; 1537 time(&long_time); 1538 localtime_r(&long_time, &t); 1539 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1540 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1541 t.tm_hour, t.tm_min, t.tm_sec); 1542 return buf; 1543} 1544 1545struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1546 return localtime_r(clock, res); 1547} 1548 1549//////////////////////////////////////////////////////////////////////////////// 1550// runtime exit support 1551 1552// Note: os::shutdown() might be called very early during initialization, or 1553// called from signal handler. Before adding something to os::shutdown(), make 1554// sure it is async-safe and can handle partially initialized VM. 1555void os::shutdown() { 1556 1557 // allow PerfMemory to attempt cleanup of any persistent resources 1558 perfMemory_exit(); 1559 1560 // needs to remove object in file system 1561 AttachListener::abort(); 1562 1563 // flush buffered output, finish log files 1564 ostream_abort(); 1565 1566 // Check for abort hook 1567 abort_hook_t abort_hook = Arguments::abort_hook(); 1568 if (abort_hook != NULL) { 1569 abort_hook(); 1570 } 1571 1572} 1573 1574// Note: os::abort() might be called very early during initialization, or 1575// called from signal handler. Before adding something to os::abort(), make 1576// sure it is async-safe and can handle partially initialized VM. 1577void os::abort(bool dump_core) { 1578 os::shutdown(); 1579 if (dump_core) { 1580#ifndef PRODUCT 1581 fdStream out(defaultStream::output_fd()); 1582 out.print_raw("Current thread is "); 1583 char buf[16]; 1584 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1585 out.print_raw_cr(buf); 1586 out.print_raw_cr("Dumping core ..."); 1587#endif 1588 ::abort(); // dump core 1589 } 1590 1591 ::exit(1); 1592} 1593 1594// Die immediately, no exit hook, no abort hook, no cleanup. 1595void os::die() { 1596 // _exit() on LinuxThreads only kills current thread 1597 ::abort(); 1598} 1599 1600// unused on linux for now. 1601void os::set_error_file(const char *logfile) {} 1602 1603 1604// This method is a copy of JDK's sysGetLastErrorString 1605// from src/solaris/hpi/src/system_md.c 1606 1607size_t os::lasterror(char *buf, size_t len) { 1608 1609 if (errno == 0) return 0; 1610 1611 const char *s = ::strerror(errno); 1612 size_t n = ::strlen(s); 1613 if (n >= len) { 1614 n = len - 1; 1615 } 1616 ::strncpy(buf, s, n); 1617 buf[n] = '\0'; 1618 return n; 1619} 1620 1621intx os::current_thread_id() { return (intx)pthread_self(); } 1622int os::current_process_id() { 1623 1624 // Under the old linux thread library, linux gives each thread 1625 // its own process id. Because of this each thread will return 1626 // a different pid if this method were to return the result 1627 // of getpid(2). Linux provides no api that returns the pid 1628 // of the launcher thread for the vm. This implementation 1629 // returns a unique pid, the pid of the launcher thread 1630 // that starts the vm 'process'. 1631 1632 // Under the NPTL, getpid() returns the same pid as the 1633 // launcher thread rather than a unique pid per thread. 1634 // Use gettid() if you want the old pre NPTL behaviour. 1635 1636 // if you are looking for the result of a call to getpid() that 1637 // returns a unique pid for the calling thread, then look at the 1638 // OSThread::thread_id() method in osThread_linux.hpp file 1639 1640 return (int)(_initial_pid ? _initial_pid : getpid()); 1641} 1642 1643// DLL functions 1644 1645const char* os::dll_file_extension() { return ".so"; } 1646 1647// This must be hard coded because it's the system's temporary 1648// directory not the java application's temp directory, ala java.io.tmpdir. 1649const char* os::get_temp_directory() { return "/tmp"; } 1650 1651static bool file_exists(const char* filename) { 1652 struct stat statbuf; 1653 if (filename == NULL || strlen(filename) == 0) { 1654 return false; 1655 } 1656 return os::stat(filename, &statbuf) == 0; 1657} 1658 1659void os::dll_build_name(char* buffer, size_t buflen, 1660 const char* pname, const char* fname) { 1661 // Copied from libhpi 1662 const size_t pnamelen = pname ? strlen(pname) : 0; 1663 1664 // Quietly truncate on buffer overflow. Should be an error. 1665 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1666 *buffer = '\0'; 1667 return; 1668 } 1669 1670 if (pnamelen == 0) { 1671 snprintf(buffer, buflen, "lib%s.so", fname); 1672 } else if (strchr(pname, *os::path_separator()) != NULL) { 1673 int n; 1674 char** pelements = split_path(pname, &n); 1675 for (int i = 0 ; i < n ; i++) { 1676 // Really shouldn't be NULL, but check can't hurt 1677 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1678 continue; // skip the empty path values 1679 } 1680 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1681 if (file_exists(buffer)) { 1682 break; 1683 } 1684 } 1685 // release the storage 1686 for (int i = 0 ; i < n ; i++) { 1687 if (pelements[i] != NULL) { 1688 FREE_C_HEAP_ARRAY(char, pelements[i]); 1689 } 1690 } 1691 if (pelements != NULL) { 1692 FREE_C_HEAP_ARRAY(char*, pelements); 1693 } 1694 } else { 1695 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1696 } 1697} 1698 1699const char* os::get_current_directory(char *buf, int buflen) { 1700 return getcwd(buf, buflen); 1701} 1702 1703// check if addr is inside libjvm[_g].so 1704bool os::address_is_in_vm(address addr) { 1705 static address libjvm_base_addr; 1706 Dl_info dlinfo; 1707 1708 if (libjvm_base_addr == NULL) { 1709 dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo); 1710 libjvm_base_addr = (address)dlinfo.dli_fbase; 1711 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1712 } 1713 1714 if (dladdr((void *)addr, &dlinfo)) { 1715 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1716 } 1717 1718 return false; 1719} 1720 1721bool os::dll_address_to_function_name(address addr, char *buf, 1722 int buflen, int *offset) { 1723 Dl_info dlinfo; 1724 1725 if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) { 1726 if (buf != NULL) { 1727 if(!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1728 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1729 } 1730 } 1731 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1732 return true; 1733 } else if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != 0) { 1734 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1735 buf, buflen, offset, dlinfo.dli_fname)) { 1736 return true; 1737 } 1738 } 1739 1740 if (buf != NULL) buf[0] = '\0'; 1741 if (offset != NULL) *offset = -1; 1742 return false; 1743} 1744 1745struct _address_to_library_name { 1746 address addr; // input : memory address 1747 size_t buflen; // size of fname 1748 char* fname; // output: library name 1749 address base; // library base addr 1750}; 1751 1752static int address_to_library_name_callback(struct dl_phdr_info *info, 1753 size_t size, void *data) { 1754 int i; 1755 bool found = false; 1756 address libbase = NULL; 1757 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1758 1759 // iterate through all loadable segments 1760 for (i = 0; i < info->dlpi_phnum; i++) { 1761 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1762 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1763 // base address of a library is the lowest address of its loaded 1764 // segments. 1765 if (libbase == NULL || libbase > segbase) { 1766 libbase = segbase; 1767 } 1768 // see if 'addr' is within current segment 1769 if (segbase <= d->addr && 1770 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1771 found = true; 1772 } 1773 } 1774 } 1775 1776 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1777 // so dll_address_to_library_name() can fall through to use dladdr() which 1778 // can figure out executable name from argv[0]. 1779 if (found && info->dlpi_name && info->dlpi_name[0]) { 1780 d->base = libbase; 1781 if (d->fname) { 1782 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1783 } 1784 return 1; 1785 } 1786 return 0; 1787} 1788 1789bool os::dll_address_to_library_name(address addr, char* buf, 1790 int buflen, int* offset) { 1791 Dl_info dlinfo; 1792 struct _address_to_library_name data; 1793 1794 // There is a bug in old glibc dladdr() implementation that it could resolve 1795 // to wrong library name if the .so file has a base address != NULL. Here 1796 // we iterate through the program headers of all loaded libraries to find 1797 // out which library 'addr' really belongs to. This workaround can be 1798 // removed once the minimum requirement for glibc is moved to 2.3.x. 1799 data.addr = addr; 1800 data.fname = buf; 1801 data.buflen = buflen; 1802 data.base = NULL; 1803 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1804 1805 if (rslt) { 1806 // buf already contains library name 1807 if (offset) *offset = addr - data.base; 1808 return true; 1809 } else if (dladdr((void*)addr, &dlinfo)){ 1810 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1811 if (offset) *offset = addr - (address)dlinfo.dli_fbase; 1812 return true; 1813 } else { 1814 if (buf) buf[0] = '\0'; 1815 if (offset) *offset = -1; 1816 return false; 1817 } 1818} 1819 1820 // Loads .dll/.so and 1821 // in case of error it checks if .dll/.so was built for the 1822 // same architecture as Hotspot is running on 1823 1824void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1825{ 1826 void * result= ::dlopen(filename, RTLD_LAZY); 1827 if (result != NULL) { 1828 // Successful loading 1829 return result; 1830 } 1831 1832 Elf32_Ehdr elf_head; 1833 1834 // Read system error message into ebuf 1835 // It may or may not be overwritten below 1836 ::strncpy(ebuf, ::dlerror(), ebuflen-1); 1837 ebuf[ebuflen-1]='\0'; 1838 int diag_msg_max_length=ebuflen-strlen(ebuf); 1839 char* diag_msg_buf=ebuf+strlen(ebuf); 1840 1841 if (diag_msg_max_length==0) { 1842 // No more space in ebuf for additional diagnostics message 1843 return NULL; 1844 } 1845 1846 1847 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1848 1849 if (file_descriptor < 0) { 1850 // Can't open library, report dlerror() message 1851 return NULL; 1852 } 1853 1854 bool failed_to_read_elf_head= 1855 (sizeof(elf_head)!= 1856 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1857 1858 ::close(file_descriptor); 1859 if (failed_to_read_elf_head) { 1860 // file i/o error - report dlerror() msg 1861 return NULL; 1862 } 1863 1864 typedef struct { 1865 Elf32_Half code; // Actual value as defined in elf.h 1866 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1867 char elf_class; // 32 or 64 bit 1868 char endianess; // MSB or LSB 1869 char* name; // String representation 1870 } arch_t; 1871 1872 #ifndef EM_486 1873 #define EM_486 6 /* Intel 80486 */ 1874 #endif 1875 1876 static const arch_t arch_array[]={ 1877 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1878 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1879 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1880 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1881 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1882 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1883 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1884 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1885 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1886 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1887 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1888 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1889 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1890 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1891 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1892 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1893 }; 1894 1895 #if (defined IA32) 1896 static Elf32_Half running_arch_code=EM_386; 1897 #elif (defined AMD64) 1898 static Elf32_Half running_arch_code=EM_X86_64; 1899 #elif (defined IA64) 1900 static Elf32_Half running_arch_code=EM_IA_64; 1901 #elif (defined __sparc) && (defined _LP64) 1902 static Elf32_Half running_arch_code=EM_SPARCV9; 1903 #elif (defined __sparc) && (!defined _LP64) 1904 static Elf32_Half running_arch_code=EM_SPARC; 1905 #elif (defined __powerpc64__) 1906 static Elf32_Half running_arch_code=EM_PPC64; 1907 #elif (defined __powerpc__) 1908 static Elf32_Half running_arch_code=EM_PPC; 1909 #elif (defined ARM) 1910 static Elf32_Half running_arch_code=EM_ARM; 1911 #elif (defined S390) 1912 static Elf32_Half running_arch_code=EM_S390; 1913 #elif (defined ALPHA) 1914 static Elf32_Half running_arch_code=EM_ALPHA; 1915 #elif (defined MIPSEL) 1916 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1917 #elif (defined PARISC) 1918 static Elf32_Half running_arch_code=EM_PARISC; 1919 #elif (defined MIPS) 1920 static Elf32_Half running_arch_code=EM_MIPS; 1921 #elif (defined M68K) 1922 static Elf32_Half running_arch_code=EM_68K; 1923 #else 1924 #error Method os::dll_load requires that one of following is defined:\ 1925 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1926 #endif 1927 1928 // Identify compatability class for VM's architecture and library's architecture 1929 // Obtain string descriptions for architectures 1930 1931 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1932 int running_arch_index=-1; 1933 1934 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 1935 if (running_arch_code == arch_array[i].code) { 1936 running_arch_index = i; 1937 } 1938 if (lib_arch.code == arch_array[i].code) { 1939 lib_arch.compat_class = arch_array[i].compat_class; 1940 lib_arch.name = arch_array[i].name; 1941 } 1942 } 1943 1944 assert(running_arch_index != -1, 1945 "Didn't find running architecture code (running_arch_code) in arch_array"); 1946 if (running_arch_index == -1) { 1947 // Even though running architecture detection failed 1948 // we may still continue with reporting dlerror() message 1949 return NULL; 1950 } 1951 1952 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1953 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1954 return NULL; 1955 } 1956 1957#ifndef S390 1958 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 1959 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 1960 return NULL; 1961 } 1962#endif // !S390 1963 1964 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 1965 if ( lib_arch.name!=NULL ) { 1966 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1967 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 1968 lib_arch.name, arch_array[running_arch_index].name); 1969 } else { 1970 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1971 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 1972 lib_arch.code, 1973 arch_array[running_arch_index].name); 1974 } 1975 } 1976 1977 return NULL; 1978} 1979 1980/* 1981 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 1982 * chances are you might want to run the generated bits against glibc-2.0 1983 * libdl.so, so always use locking for any version of glibc. 1984 */ 1985void* os::dll_lookup(void* handle, const char* name) { 1986 pthread_mutex_lock(&dl_mutex); 1987 void* res = dlsym(handle, name); 1988 pthread_mutex_unlock(&dl_mutex); 1989 return res; 1990} 1991 1992 1993static bool _print_ascii_file(const char* filename, outputStream* st) { 1994 int fd = ::open(filename, O_RDONLY); 1995 if (fd == -1) { 1996 return false; 1997 } 1998 1999 char buf[32]; 2000 int bytes; 2001 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2002 st->print_raw(buf, bytes); 2003 } 2004 2005 ::close(fd); 2006 2007 return true; 2008} 2009 2010void os::print_dll_info(outputStream *st) { 2011 st->print_cr("Dynamic libraries:"); 2012 2013 char fname[32]; 2014 pid_t pid = os::Linux::gettid(); 2015 2016 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2017 2018 if (!_print_ascii_file(fname, st)) { 2019 st->print("Can not get library information for pid = %d\n", pid); 2020 } 2021} 2022 2023 2024void os::print_os_info(outputStream* st) { 2025 st->print("OS:"); 2026 2027 // Try to identify popular distros. 2028 // Most Linux distributions have /etc/XXX-release file, which contains 2029 // the OS version string. Some have more than one /etc/XXX-release file 2030 // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.), 2031 // so the order is important. 2032 if (!_print_ascii_file("/etc/mandrake-release", st) && 2033 !_print_ascii_file("/etc/sun-release", st) && 2034 !_print_ascii_file("/etc/redhat-release", st) && 2035 !_print_ascii_file("/etc/SuSE-release", st) && 2036 !_print_ascii_file("/etc/turbolinux-release", st) && 2037 !_print_ascii_file("/etc/gentoo-release", st) && 2038 !_print_ascii_file("/etc/debian_version", st) && 2039 !_print_ascii_file("/etc/ltib-release", st) && 2040 !_print_ascii_file("/etc/angstrom-version", st)) { 2041 st->print("Linux"); 2042 } 2043 st->cr(); 2044 2045 // kernel 2046 st->print("uname:"); 2047 struct utsname name; 2048 uname(&name); 2049 st->print(name.sysname); st->print(" "); 2050 st->print(name.release); st->print(" "); 2051 st->print(name.version); st->print(" "); 2052 st->print(name.machine); 2053 st->cr(); 2054 2055 // Print warning if unsafe chroot environment detected 2056 if (unsafe_chroot_detected) { 2057 st->print("WARNING!! "); 2058 st->print_cr(unstable_chroot_error); 2059 } 2060 2061 // libc, pthread 2062 st->print("libc:"); 2063 st->print(os::Linux::glibc_version()); st->print(" "); 2064 st->print(os::Linux::libpthread_version()); st->print(" "); 2065 if (os::Linux::is_LinuxThreads()) { 2066 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2067 } 2068 st->cr(); 2069 2070 // rlimit 2071 st->print("rlimit:"); 2072 struct rlimit rlim; 2073 2074 st->print(" STACK "); 2075 getrlimit(RLIMIT_STACK, &rlim); 2076 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 2077 else st->print("%uk", rlim.rlim_cur >> 10); 2078 2079 st->print(", CORE "); 2080 getrlimit(RLIMIT_CORE, &rlim); 2081 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 2082 else st->print("%uk", rlim.rlim_cur >> 10); 2083 2084 st->print(", NPROC "); 2085 getrlimit(RLIMIT_NPROC, &rlim); 2086 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 2087 else st->print("%d", rlim.rlim_cur); 2088 2089 st->print(", NOFILE "); 2090 getrlimit(RLIMIT_NOFILE, &rlim); 2091 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 2092 else st->print("%d", rlim.rlim_cur); 2093 2094 st->print(", AS "); 2095 getrlimit(RLIMIT_AS, &rlim); 2096 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 2097 else st->print("%uk", rlim.rlim_cur >> 10); 2098 st->cr(); 2099 2100 // load average 2101 st->print("load average:"); 2102 double loadavg[3]; 2103 os::loadavg(loadavg, 3); 2104 st->print("%0.02f %0.02f %0.02f", loadavg[0], loadavg[1], loadavg[2]); 2105 st->cr(); 2106 2107 // meminfo 2108 st->print("\n/proc/meminfo:\n"); 2109 _print_ascii_file("/proc/meminfo", st); 2110 st->cr(); 2111} 2112 2113void os::pd_print_cpu_info(outputStream* st) { 2114 st->print("\n/proc/cpuinfo:\n"); 2115 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2116 st->print(" <Not Available>"); 2117 } 2118 st->cr(); 2119} 2120 2121void os::print_memory_info(outputStream* st) { 2122 2123 st->print("Memory:"); 2124 st->print(" %dk page", os::vm_page_size()>>10); 2125 2126 // values in struct sysinfo are "unsigned long" 2127 struct sysinfo si; 2128 sysinfo(&si); 2129 2130 st->print(", physical " UINT64_FORMAT "k", 2131 os::physical_memory() >> 10); 2132 st->print("(" UINT64_FORMAT "k free)", 2133 os::available_memory() >> 10); 2134 st->print(", swap " UINT64_FORMAT "k", 2135 ((jlong)si.totalswap * si.mem_unit) >> 10); 2136 st->print("(" UINT64_FORMAT "k free)", 2137 ((jlong)si.freeswap * si.mem_unit) >> 10); 2138 st->cr(); 2139} 2140 2141// Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific 2142// but they're the same for all the linux arch that we support 2143// and they're the same for solaris but there's no common place to put this. 2144const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR", 2145 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG", 2146 "ILL_COPROC", "ILL_BADSTK" }; 2147 2148const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV", 2149 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES", 2150 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" }; 2151 2152const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" }; 2153 2154const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" }; 2155 2156void os::print_siginfo(outputStream* st, void* siginfo) { 2157 st->print("siginfo:"); 2158 2159 const int buflen = 100; 2160 char buf[buflen]; 2161 siginfo_t *si = (siginfo_t*)siginfo; 2162 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen)); 2163 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) { 2164 st->print("si_errno=%s", buf); 2165 } else { 2166 st->print("si_errno=%d", si->si_errno); 2167 } 2168 const int c = si->si_code; 2169 assert(c > 0, "unexpected si_code"); 2170 switch (si->si_signo) { 2171 case SIGILL: 2172 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]); 2173 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2174 break; 2175 case SIGFPE: 2176 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]); 2177 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2178 break; 2179 case SIGSEGV: 2180 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]); 2181 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2182 break; 2183 case SIGBUS: 2184 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]); 2185 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2186 break; 2187 default: 2188 st->print(", si_code=%d", si->si_code); 2189 // no si_addr 2190 } 2191 2192 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2193 UseSharedSpaces) { 2194 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2195 if (mapinfo->is_in_shared_space(si->si_addr)) { 2196 st->print("\n\nError accessing class data sharing archive." \ 2197 " Mapped file inaccessible during execution, " \ 2198 " possible disk/network problem."); 2199 } 2200 } 2201 st->cr(); 2202} 2203 2204 2205static void print_signal_handler(outputStream* st, int sig, 2206 char* buf, size_t buflen); 2207 2208void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2209 st->print_cr("Signal Handlers:"); 2210 print_signal_handler(st, SIGSEGV, buf, buflen); 2211 print_signal_handler(st, SIGBUS , buf, buflen); 2212 print_signal_handler(st, SIGFPE , buf, buflen); 2213 print_signal_handler(st, SIGPIPE, buf, buflen); 2214 print_signal_handler(st, SIGXFSZ, buf, buflen); 2215 print_signal_handler(st, SIGILL , buf, buflen); 2216 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2217 print_signal_handler(st, SR_signum, buf, buflen); 2218 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2219 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2220 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2221 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2222} 2223 2224static char saved_jvm_path[MAXPATHLEN] = {0}; 2225 2226// Find the full path to the current module, libjvm.so or libjvm_g.so 2227void os::jvm_path(char *buf, jint buflen) { 2228 // Error checking. 2229 if (buflen < MAXPATHLEN) { 2230 assert(false, "must use a large-enough buffer"); 2231 buf[0] = '\0'; 2232 return; 2233 } 2234 // Lazy resolve the path to current module. 2235 if (saved_jvm_path[0] != 0) { 2236 strcpy(buf, saved_jvm_path); 2237 return; 2238 } 2239 2240 char dli_fname[MAXPATHLEN]; 2241 bool ret = dll_address_to_library_name( 2242 CAST_FROM_FN_PTR(address, os::jvm_path), 2243 dli_fname, sizeof(dli_fname), NULL); 2244 assert(ret != 0, "cannot locate libjvm"); 2245 char *rp = realpath(dli_fname, buf); 2246 if (rp == NULL) 2247 return; 2248 2249 if (Arguments::created_by_gamma_launcher()) { 2250 // Support for the gamma launcher. Typical value for buf is 2251 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at 2252 // the right place in the string, then assume we are installed in a JDK and 2253 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix 2254 // up the path so it looks like libjvm.so is installed there (append a 2255 // fake suffix hotspot/libjvm.so). 2256 const char *p = buf + strlen(buf) - 1; 2257 for (int count = 0; p > buf && count < 5; ++count) { 2258 for (--p; p > buf && *p != '/'; --p) 2259 /* empty */ ; 2260 } 2261 2262 if (strncmp(p, "/jre/lib/", 9) != 0) { 2263 // Look for JAVA_HOME in the environment. 2264 char* java_home_var = ::getenv("JAVA_HOME"); 2265 if (java_home_var != NULL && java_home_var[0] != 0) { 2266 char* jrelib_p; 2267 int len; 2268 2269 // Check the current module name "libjvm.so" or "libjvm_g.so". 2270 p = strrchr(buf, '/'); 2271 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2272 p = strstr(p, "_g") ? "_g" : ""; 2273 2274 rp = realpath(java_home_var, buf); 2275 if (rp == NULL) 2276 return; 2277 2278 // determine if this is a legacy image or modules image 2279 // modules image doesn't have "jre" subdirectory 2280 len = strlen(buf); 2281 jrelib_p = buf + len; 2282 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2283 if (0 != access(buf, F_OK)) { 2284 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2285 } 2286 2287 if (0 == access(buf, F_OK)) { 2288 // Use current module name "libjvm[_g].so" instead of 2289 // "libjvm"debug_only("_g")".so" since for fastdebug version 2290 // we should have "libjvm.so" but debug_only("_g") adds "_g"! 2291 len = strlen(buf); 2292 snprintf(buf + len, buflen-len, "/hotspot/libjvm%s.so", p); 2293 } else { 2294 // Go back to path of .so 2295 rp = realpath(dli_fname, buf); 2296 if (rp == NULL) 2297 return; 2298 } 2299 } 2300 } 2301 } 2302 2303 strcpy(saved_jvm_path, buf); 2304} 2305 2306void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2307 // no prefix required, not even "_" 2308} 2309 2310void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2311 // no suffix required 2312} 2313 2314//////////////////////////////////////////////////////////////////////////////// 2315// sun.misc.Signal support 2316 2317static volatile jint sigint_count = 0; 2318 2319static void 2320UserHandler(int sig, void *siginfo, void *context) { 2321 // 4511530 - sem_post is serialized and handled by the manager thread. When 2322 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2323 // don't want to flood the manager thread with sem_post requests. 2324 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2325 return; 2326 2327 // Ctrl-C is pressed during error reporting, likely because the error 2328 // handler fails to abort. Let VM die immediately. 2329 if (sig == SIGINT && is_error_reported()) { 2330 os::die(); 2331 } 2332 2333 os::signal_notify(sig); 2334} 2335 2336void* os::user_handler() { 2337 return CAST_FROM_FN_PTR(void*, UserHandler); 2338} 2339 2340extern "C" { 2341 typedef void (*sa_handler_t)(int); 2342 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2343} 2344 2345void* os::signal(int signal_number, void* handler) { 2346 struct sigaction sigAct, oldSigAct; 2347 2348 sigfillset(&(sigAct.sa_mask)); 2349 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2350 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2351 2352 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2353 // -1 means registration failed 2354 return (void *)-1; 2355 } 2356 2357 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2358} 2359 2360void os::signal_raise(int signal_number) { 2361 ::raise(signal_number); 2362} 2363 2364/* 2365 * The following code is moved from os.cpp for making this 2366 * code platform specific, which it is by its very nature. 2367 */ 2368 2369// Will be modified when max signal is changed to be dynamic 2370int os::sigexitnum_pd() { 2371 return NSIG; 2372} 2373 2374// a counter for each possible signal value 2375static volatile jint pending_signals[NSIG+1] = { 0 }; 2376 2377// Linux(POSIX) specific hand shaking semaphore. 2378static sem_t sig_sem; 2379 2380void os::signal_init_pd() { 2381 // Initialize signal structures 2382 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2383 2384 // Initialize signal semaphore 2385 ::sem_init(&sig_sem, 0, 0); 2386} 2387 2388void os::signal_notify(int sig) { 2389 Atomic::inc(&pending_signals[sig]); 2390 ::sem_post(&sig_sem); 2391} 2392 2393static int check_pending_signals(bool wait) { 2394 Atomic::store(0, &sigint_count); 2395 for (;;) { 2396 for (int i = 0; i < NSIG + 1; i++) { 2397 jint n = pending_signals[i]; 2398 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2399 return i; 2400 } 2401 } 2402 if (!wait) { 2403 return -1; 2404 } 2405 JavaThread *thread = JavaThread::current(); 2406 ThreadBlockInVM tbivm(thread); 2407 2408 bool threadIsSuspended; 2409 do { 2410 thread->set_suspend_equivalent(); 2411 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2412 ::sem_wait(&sig_sem); 2413 2414 // were we externally suspended while we were waiting? 2415 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2416 if (threadIsSuspended) { 2417 // 2418 // The semaphore has been incremented, but while we were waiting 2419 // another thread suspended us. We don't want to continue running 2420 // while suspended because that would surprise the thread that 2421 // suspended us. 2422 // 2423 ::sem_post(&sig_sem); 2424 2425 thread->java_suspend_self(); 2426 } 2427 } while (threadIsSuspended); 2428 } 2429} 2430 2431int os::signal_lookup() { 2432 return check_pending_signals(false); 2433} 2434 2435int os::signal_wait() { 2436 return check_pending_signals(true); 2437} 2438 2439//////////////////////////////////////////////////////////////////////////////// 2440// Virtual Memory 2441 2442int os::vm_page_size() { 2443 // Seems redundant as all get out 2444 assert(os::Linux::page_size() != -1, "must call os::init"); 2445 return os::Linux::page_size(); 2446} 2447 2448// Solaris allocates memory by pages. 2449int os::vm_allocation_granularity() { 2450 assert(os::Linux::page_size() != -1, "must call os::init"); 2451 return os::Linux::page_size(); 2452} 2453 2454// Rationale behind this function: 2455// current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2456// mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2457// samples for JITted code. Here we create private executable mapping over the code cache 2458// and then we can use standard (well, almost, as mapping can change) way to provide 2459// info for the reporting script by storing timestamp and location of symbol 2460void linux_wrap_code(char* base, size_t size) { 2461 static volatile jint cnt = 0; 2462 2463 if (!UseOprofile) { 2464 return; 2465 } 2466 2467 char buf[PATH_MAX+1]; 2468 int num = Atomic::add(1, &cnt); 2469 2470 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2471 os::get_temp_directory(), os::current_process_id(), num); 2472 unlink(buf); 2473 2474 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2475 2476 if (fd != -1) { 2477 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2478 if (rv != (off_t)-1) { 2479 if (::write(fd, "", 1) == 1) { 2480 mmap(base, size, 2481 PROT_READ|PROT_WRITE|PROT_EXEC, 2482 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2483 } 2484 } 2485 ::close(fd); 2486 unlink(buf); 2487 } 2488} 2489 2490// NOTE: Linux kernel does not really reserve the pages for us. 2491// All it does is to check if there are enough free pages 2492// left at the time of mmap(). This could be a potential 2493// problem. 2494bool os::commit_memory(char* addr, size_t size, bool exec) { 2495 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2496 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2497 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2498 if (res != (uintptr_t) MAP_FAILED) { 2499 if (UseNUMAInterleaving) { 2500 numa_make_global(addr, size); 2501 } 2502 return true; 2503 } 2504 return false; 2505} 2506 2507// Define MAP_HUGETLB here so we can build HotSpot on old systems. 2508#ifndef MAP_HUGETLB 2509#define MAP_HUGETLB 0x40000 2510#endif 2511 2512// Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2513#ifndef MADV_HUGEPAGE 2514#define MADV_HUGEPAGE 14 2515#endif 2516 2517bool os::commit_memory(char* addr, size_t size, size_t alignment_hint, 2518 bool exec) { 2519 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) { 2520 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2521 uintptr_t res = 2522 (uintptr_t) ::mmap(addr, size, prot, 2523 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_HUGETLB, 2524 -1, 0); 2525 if (res != (uintptr_t) MAP_FAILED) { 2526 if (UseNUMAInterleaving) { 2527 numa_make_global(addr, size); 2528 } 2529 return true; 2530 } 2531 // Fall through and try to use small pages 2532 } 2533 2534 if (commit_memory(addr, size, exec)) { 2535 realign_memory(addr, size, alignment_hint); 2536 return true; 2537 } 2538 return false; 2539} 2540 2541void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2542 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) { 2543 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2544 // be supported or the memory may already be backed by huge pages. 2545 ::madvise(addr, bytes, MADV_HUGEPAGE); 2546 } 2547} 2548 2549void os::free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2550 // This method works by doing an mmap over an existing mmaping and effectively discarding 2551 // the existing pages. However it won't work for SHM-based large pages that cannot be 2552 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2553 // small pages on top of the SHM segment. This method always works for small pages, so we 2554 // allow that in any case. 2555 if (alignment_hint <= (size_t)os::vm_page_size() || !UseSHM) { 2556 commit_memory(addr, bytes, alignment_hint, false); 2557 } 2558} 2559 2560void os::numa_make_global(char *addr, size_t bytes) { 2561 Linux::numa_interleave_memory(addr, bytes); 2562} 2563 2564void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2565 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2566} 2567 2568bool os::numa_topology_changed() { return false; } 2569 2570size_t os::numa_get_groups_num() { 2571 int max_node = Linux::numa_max_node(); 2572 return max_node > 0 ? max_node + 1 : 1; 2573} 2574 2575int os::numa_get_group_id() { 2576 int cpu_id = Linux::sched_getcpu(); 2577 if (cpu_id != -1) { 2578 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2579 if (lgrp_id != -1) { 2580 return lgrp_id; 2581 } 2582 } 2583 return 0; 2584} 2585 2586size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2587 for (size_t i = 0; i < size; i++) { 2588 ids[i] = i; 2589 } 2590 return size; 2591} 2592 2593bool os::get_page_info(char *start, page_info* info) { 2594 return false; 2595} 2596 2597char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2598 return end; 2599} 2600 2601 2602int os::Linux::sched_getcpu_syscall(void) { 2603 unsigned int cpu; 2604 int retval = -1; 2605 2606#if defined(IA32) 2607# ifndef SYS_getcpu 2608# define SYS_getcpu 318 2609# endif 2610 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2611#elif defined(AMD64) 2612// Unfortunately we have to bring all these macros here from vsyscall.h 2613// to be able to compile on old linuxes. 2614# define __NR_vgetcpu 2 2615# define VSYSCALL_START (-10UL << 20) 2616# define VSYSCALL_SIZE 1024 2617# define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2618 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2619 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2620 retval = vgetcpu(&cpu, NULL, NULL); 2621#endif 2622 2623 return (retval == -1) ? retval : cpu; 2624} 2625 2626// Something to do with the numa-aware allocator needs these symbols 2627extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2628extern "C" JNIEXPORT void numa_error(char *where) { } 2629extern "C" JNIEXPORT int fork1() { return fork(); } 2630 2631 2632// If we are running with libnuma version > 2, then we should 2633// be trying to use symbols with versions 1.1 2634// If we are running with earlier version, which did not have symbol versions, 2635// we should use the base version. 2636void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2637 void *f = dlvsym(handle, name, "libnuma_1.1"); 2638 if (f == NULL) { 2639 f = dlsym(handle, name); 2640 } 2641 return f; 2642} 2643 2644bool os::Linux::libnuma_init() { 2645 // sched_getcpu() should be in libc. 2646 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2647 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2648 2649 // If it's not, try a direct syscall. 2650 if (sched_getcpu() == -1) 2651 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall)); 2652 2653 if (sched_getcpu() != -1) { // Does it work? 2654 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2655 if (handle != NULL) { 2656 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2657 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2658 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2659 libnuma_dlsym(handle, "numa_max_node"))); 2660 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2661 libnuma_dlsym(handle, "numa_available"))); 2662 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2663 libnuma_dlsym(handle, "numa_tonode_memory"))); 2664 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2665 libnuma_dlsym(handle, "numa_interleave_memory"))); 2666 2667 2668 if (numa_available() != -1) { 2669 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2670 // Create a cpu -> node mapping 2671 _cpu_to_node = new (ResourceObj::C_HEAP) GrowableArray<int>(0, true); 2672 rebuild_cpu_to_node_map(); 2673 return true; 2674 } 2675 } 2676 } 2677 return false; 2678} 2679 2680// rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2681// The table is later used in get_node_by_cpu(). 2682void os::Linux::rebuild_cpu_to_node_map() { 2683 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2684 // in libnuma (possible values are starting from 16, 2685 // and continuing up with every other power of 2, but less 2686 // than the maximum number of CPUs supported by kernel), and 2687 // is a subject to change (in libnuma version 2 the requirements 2688 // are more reasonable) we'll just hardcode the number they use 2689 // in the library. 2690 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2691 2692 size_t cpu_num = os::active_processor_count(); 2693 size_t cpu_map_size = NCPUS / BitsPerCLong; 2694 size_t cpu_map_valid_size = 2695 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2696 2697 cpu_to_node()->clear(); 2698 cpu_to_node()->at_grow(cpu_num - 1); 2699 size_t node_num = numa_get_groups_num(); 2700 2701 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size); 2702 for (size_t i = 0; i < node_num; i++) { 2703 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2704 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2705 if (cpu_map[j] != 0) { 2706 for (size_t k = 0; k < BitsPerCLong; k++) { 2707 if (cpu_map[j] & (1UL << k)) { 2708 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2709 } 2710 } 2711 } 2712 } 2713 } 2714 } 2715 FREE_C_HEAP_ARRAY(unsigned long, cpu_map); 2716} 2717 2718int os::Linux::get_node_by_cpu(int cpu_id) { 2719 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2720 return cpu_to_node()->at(cpu_id); 2721 } 2722 return -1; 2723} 2724 2725GrowableArray<int>* os::Linux::_cpu_to_node; 2726os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2727os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2728os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2729os::Linux::numa_available_func_t os::Linux::_numa_available; 2730os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2731os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2732unsigned long* os::Linux::_numa_all_nodes; 2733 2734bool os::uncommit_memory(char* addr, size_t size) { 2735 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2736 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2737 return res != (uintptr_t) MAP_FAILED; 2738} 2739 2740// Linux uses a growable mapping for the stack, and if the mapping for 2741// the stack guard pages is not removed when we detach a thread the 2742// stack cannot grow beyond the pages where the stack guard was 2743// mapped. If at some point later in the process the stack expands to 2744// that point, the Linux kernel cannot expand the stack any further 2745// because the guard pages are in the way, and a segfault occurs. 2746// 2747// However, it's essential not to split the stack region by unmapping 2748// a region (leaving a hole) that's already part of the stack mapping, 2749// so if the stack mapping has already grown beyond the guard pages at 2750// the time we create them, we have to truncate the stack mapping. 2751// So, we need to know the extent of the stack mapping when 2752// create_stack_guard_pages() is called. 2753 2754// Find the bounds of the stack mapping. Return true for success. 2755// 2756// We only need this for stacks that are growable: at the time of 2757// writing thread stacks don't use growable mappings (i.e. those 2758// creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 2759// only applies to the main thread. 2760 2761static 2762bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) { 2763 2764 char buf[128]; 2765 int fd, sz; 2766 2767 if ((fd = ::open("/proc/self/maps", O_RDONLY)) < 0) { 2768 return false; 2769 } 2770 2771 const char kw[] = "[stack]"; 2772 const int kwlen = sizeof(kw)-1; 2773 2774 // Address part of /proc/self/maps couldn't be more than 128 bytes 2775 while ((sz = os::get_line_chars(fd, buf, sizeof(buf))) > 0) { 2776 if (sz > kwlen && ::memcmp(buf+sz-kwlen, kw, kwlen) == 0) { 2777 // Extract addresses 2778 if (sscanf(buf, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) { 2779 uintptr_t sp = (uintptr_t) __builtin_frame_address(0); 2780 if (sp >= *bottom && sp <= *top) { 2781 ::close(fd); 2782 return true; 2783 } 2784 } 2785 } 2786 } 2787 2788 ::close(fd); 2789 return false; 2790} 2791 2792 2793// If the (growable) stack mapping already extends beyond the point 2794// where we're going to put our guard pages, truncate the mapping at 2795// that point by munmap()ping it. This ensures that when we later 2796// munmap() the guard pages we don't leave a hole in the stack 2797// mapping. This only affects the main/initial thread, but guard 2798// against future OS changes 2799bool os::create_stack_guard_pages(char* addr, size_t size) { 2800 uintptr_t stack_extent, stack_base; 2801 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true); 2802 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) { 2803 assert(os::Linux::is_initial_thread(), 2804 "growable stack in non-initial thread"); 2805 if (stack_extent < (uintptr_t)addr) 2806 ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent); 2807 } 2808 2809 return os::commit_memory(addr, size); 2810} 2811 2812// If this is a growable mapping, remove the guard pages entirely by 2813// munmap()ping them. If not, just call uncommit_memory(). This only 2814// affects the main/initial thread, but guard against future OS changes 2815bool os::remove_stack_guard_pages(char* addr, size_t size) { 2816 uintptr_t stack_extent, stack_base; 2817 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true); 2818 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) { 2819 assert(os::Linux::is_initial_thread(), 2820 "growable stack in non-initial thread"); 2821 2822 return ::munmap(addr, size) == 0; 2823 } 2824 2825 return os::uncommit_memory(addr, size); 2826} 2827 2828static address _highest_vm_reserved_address = NULL; 2829 2830// If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 2831// at 'requested_addr'. If there are existing memory mappings at the same 2832// location, however, they will be overwritten. If 'fixed' is false, 2833// 'requested_addr' is only treated as a hint, the return value may or 2834// may not start from the requested address. Unlike Linux mmap(), this 2835// function returns NULL to indicate failure. 2836static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 2837 char * addr; 2838 int flags; 2839 2840 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 2841 if (fixed) { 2842 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 2843 flags |= MAP_FIXED; 2844 } 2845 2846 // Map uncommitted pages PROT_READ and PROT_WRITE, change access 2847 // to PROT_EXEC if executable when we commit the page. 2848 addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE, 2849 flags, -1, 0); 2850 2851 if (addr != MAP_FAILED) { 2852 // anon_mmap() should only get called during VM initialization, 2853 // don't need lock (actually we can skip locking even it can be called 2854 // from multiple threads, because _highest_vm_reserved_address is just a 2855 // hint about the upper limit of non-stack memory regions.) 2856 if ((address)addr + bytes > _highest_vm_reserved_address) { 2857 _highest_vm_reserved_address = (address)addr + bytes; 2858 } 2859 } 2860 2861 return addr == MAP_FAILED ? NULL : addr; 2862} 2863 2864// Don't update _highest_vm_reserved_address, because there might be memory 2865// regions above addr + size. If so, releasing a memory region only creates 2866// a hole in the address space, it doesn't help prevent heap-stack collision. 2867// 2868static int anon_munmap(char * addr, size_t size) { 2869 return ::munmap(addr, size) == 0; 2870} 2871 2872char* os::reserve_memory(size_t bytes, char* requested_addr, 2873 size_t alignment_hint) { 2874 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 2875} 2876 2877bool os::release_memory(char* addr, size_t size) { 2878 return anon_munmap(addr, size); 2879} 2880 2881static address highest_vm_reserved_address() { 2882 return _highest_vm_reserved_address; 2883} 2884 2885static bool linux_mprotect(char* addr, size_t size, int prot) { 2886 // Linux wants the mprotect address argument to be page aligned. 2887 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 2888 2889 // According to SUSv3, mprotect() should only be used with mappings 2890 // established by mmap(), and mmap() always maps whole pages. Unaligned 2891 // 'addr' likely indicates problem in the VM (e.g. trying to change 2892 // protection of malloc'ed or statically allocated memory). Check the 2893 // caller if you hit this assert. 2894 assert(addr == bottom, "sanity check"); 2895 2896 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 2897 return ::mprotect(bottom, size, prot) == 0; 2898} 2899 2900// Set protections specified 2901bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 2902 bool is_committed) { 2903 unsigned int p = 0; 2904 switch (prot) { 2905 case MEM_PROT_NONE: p = PROT_NONE; break; 2906 case MEM_PROT_READ: p = PROT_READ; break; 2907 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 2908 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 2909 default: 2910 ShouldNotReachHere(); 2911 } 2912 // is_committed is unused. 2913 return linux_mprotect(addr, bytes, p); 2914} 2915 2916bool os::guard_memory(char* addr, size_t size) { 2917 return linux_mprotect(addr, size, PROT_NONE); 2918} 2919 2920bool os::unguard_memory(char* addr, size_t size) { 2921 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 2922} 2923 2924bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 2925 bool result = false; 2926 void *p = mmap (NULL, page_size, PROT_READ|PROT_WRITE, 2927 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 2928 -1, 0); 2929 2930 if (p != (void *) -1) { 2931 // We don't know if this really is a huge page or not. 2932 FILE *fp = fopen("/proc/self/maps", "r"); 2933 if (fp) { 2934 while (!feof(fp)) { 2935 char chars[257]; 2936 long x = 0; 2937 if (fgets(chars, sizeof(chars), fp)) { 2938 if (sscanf(chars, "%lx-%*x", &x) == 1 2939 && x == (long)p) { 2940 if (strstr (chars, "hugepage")) { 2941 result = true; 2942 break; 2943 } 2944 } 2945 } 2946 } 2947 fclose(fp); 2948 } 2949 munmap (p, page_size); 2950 if (result) 2951 return true; 2952 } 2953 2954 if (warn) { 2955 warning("HugeTLBFS is not supported by the operating system."); 2956 } 2957 2958 return result; 2959} 2960 2961/* 2962* Set the coredump_filter bits to include largepages in core dump (bit 6) 2963* 2964* From the coredump_filter documentation: 2965* 2966* - (bit 0) anonymous private memory 2967* - (bit 1) anonymous shared memory 2968* - (bit 2) file-backed private memory 2969* - (bit 3) file-backed shared memory 2970* - (bit 4) ELF header pages in file-backed private memory areas (it is 2971* effective only if the bit 2 is cleared) 2972* - (bit 5) hugetlb private memory 2973* - (bit 6) hugetlb shared memory 2974*/ 2975static void set_coredump_filter(void) { 2976 FILE *f; 2977 long cdm; 2978 2979 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 2980 return; 2981 } 2982 2983 if (fscanf(f, "%lx", &cdm) != 1) { 2984 fclose(f); 2985 return; 2986 } 2987 2988 rewind(f); 2989 2990 if ((cdm & LARGEPAGES_BIT) == 0) { 2991 cdm |= LARGEPAGES_BIT; 2992 fprintf(f, "%#lx", cdm); 2993 } 2994 2995 fclose(f); 2996} 2997 2998// Large page support 2999 3000static size_t _large_page_size = 0; 3001 3002void os::large_page_init() { 3003 if (!UseLargePages) { 3004 UseHugeTLBFS = false; 3005 UseSHM = false; 3006 return; 3007 } 3008 3009 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && FLAG_IS_DEFAULT(UseSHM)) { 3010 // If UseLargePages is specified on the command line try both methods, 3011 // if it's default, then try only HugeTLBFS. 3012 if (FLAG_IS_DEFAULT(UseLargePages)) { 3013 UseHugeTLBFS = true; 3014 } else { 3015 UseHugeTLBFS = UseSHM = true; 3016 } 3017 } 3018 3019 if (LargePageSizeInBytes) { 3020 _large_page_size = LargePageSizeInBytes; 3021 } else { 3022 // large_page_size on Linux is used to round up heap size. x86 uses either 3023 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3024 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3025 // page as large as 256M. 3026 // 3027 // Here we try to figure out page size by parsing /proc/meminfo and looking 3028 // for a line with the following format: 3029 // Hugepagesize: 2048 kB 3030 // 3031 // If we can't determine the value (e.g. /proc is not mounted, or the text 3032 // format has been changed), we'll use the largest page size supported by 3033 // the processor. 3034 3035#ifndef ZERO 3036 _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3037 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3038#endif // ZERO 3039 3040 FILE *fp = fopen("/proc/meminfo", "r"); 3041 if (fp) { 3042 while (!feof(fp)) { 3043 int x = 0; 3044 char buf[16]; 3045 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3046 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3047 _large_page_size = x * K; 3048 break; 3049 } 3050 } else { 3051 // skip to next line 3052 for (;;) { 3053 int ch = fgetc(fp); 3054 if (ch == EOF || ch == (int)'\n') break; 3055 } 3056 } 3057 } 3058 fclose(fp); 3059 } 3060 } 3061 3062 // print a warning if any large page related flag is specified on command line 3063 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3064 3065 const size_t default_page_size = (size_t)Linux::page_size(); 3066 if (_large_page_size > default_page_size) { 3067 _page_sizes[0] = _large_page_size; 3068 _page_sizes[1] = default_page_size; 3069 _page_sizes[2] = 0; 3070 } 3071 UseHugeTLBFS = UseHugeTLBFS && 3072 Linux::hugetlbfs_sanity_check(warn_on_failure, _large_page_size); 3073 3074 if (UseHugeTLBFS) 3075 UseSHM = false; 3076 3077 UseLargePages = UseHugeTLBFS || UseSHM; 3078 3079 set_coredump_filter(); 3080} 3081 3082#ifndef SHM_HUGETLB 3083#define SHM_HUGETLB 04000 3084#endif 3085 3086char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) { 3087 // "exec" is passed in but not used. Creating the shared image for 3088 // the code cache doesn't have an SHM_X executable permission to check. 3089 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3090 3091 key_t key = IPC_PRIVATE; 3092 char *addr; 3093 3094 bool warn_on_failure = UseLargePages && 3095 (!FLAG_IS_DEFAULT(UseLargePages) || 3096 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 3097 ); 3098 char msg[128]; 3099 3100 // Create a large shared memory region to attach to based on size. 3101 // Currently, size is the total size of the heap 3102 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3103 if (shmid == -1) { 3104 // Possible reasons for shmget failure: 3105 // 1. shmmax is too small for Java heap. 3106 // > check shmmax value: cat /proc/sys/kernel/shmmax 3107 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3108 // 2. not enough large page memory. 3109 // > check available large pages: cat /proc/meminfo 3110 // > increase amount of large pages: 3111 // echo new_value > /proc/sys/vm/nr_hugepages 3112 // Note 1: different Linux may use different name for this property, 3113 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3114 // Note 2: it's possible there's enough physical memory available but 3115 // they are so fragmented after a long run that they can't 3116 // coalesce into large pages. Try to reserve large pages when 3117 // the system is still "fresh". 3118 if (warn_on_failure) { 3119 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3120 warning(msg); 3121 } 3122 return NULL; 3123 } 3124 3125 // attach to the region 3126 addr = (char*)shmat(shmid, req_addr, 0); 3127 int err = errno; 3128 3129 // Remove shmid. If shmat() is successful, the actual shared memory segment 3130 // will be deleted when it's detached by shmdt() or when the process 3131 // terminates. If shmat() is not successful this will remove the shared 3132 // segment immediately. 3133 shmctl(shmid, IPC_RMID, NULL); 3134 3135 if ((intptr_t)addr == -1) { 3136 if (warn_on_failure) { 3137 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3138 warning(msg); 3139 } 3140 return NULL; 3141 } 3142 3143 if ((addr != NULL) && UseNUMAInterleaving) { 3144 numa_make_global(addr, bytes); 3145 } 3146 3147 return addr; 3148} 3149 3150bool os::release_memory_special(char* base, size_t bytes) { 3151 // detaching the SHM segment will also delete it, see reserve_memory_special() 3152 int rslt = shmdt(base); 3153 return rslt == 0; 3154} 3155 3156size_t os::large_page_size() { 3157 return _large_page_size; 3158} 3159 3160// HugeTLBFS allows application to commit large page memory on demand; 3161// with SysV SHM the entire memory region must be allocated as shared 3162// memory. 3163bool os::can_commit_large_page_memory() { 3164 return UseHugeTLBFS; 3165} 3166 3167bool os::can_execute_large_page_memory() { 3168 return UseHugeTLBFS; 3169} 3170 3171// Reserve memory at an arbitrary address, only if that area is 3172// available (and not reserved for something else). 3173 3174char* os::attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3175 const int max_tries = 10; 3176 char* base[max_tries]; 3177 size_t size[max_tries]; 3178 const size_t gap = 0x000000; 3179 3180 // Assert only that the size is a multiple of the page size, since 3181 // that's all that mmap requires, and since that's all we really know 3182 // about at this low abstraction level. If we need higher alignment, 3183 // we can either pass an alignment to this method or verify alignment 3184 // in one of the methods further up the call chain. See bug 5044738. 3185 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3186 3187 // Repeatedly allocate blocks until the block is allocated at the 3188 // right spot. Give up after max_tries. Note that reserve_memory() will 3189 // automatically update _highest_vm_reserved_address if the call is 3190 // successful. The variable tracks the highest memory address every reserved 3191 // by JVM. It is used to detect heap-stack collision if running with 3192 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3193 // space than needed, it could confuse the collision detecting code. To 3194 // solve the problem, save current _highest_vm_reserved_address and 3195 // calculate the correct value before return. 3196 address old_highest = _highest_vm_reserved_address; 3197 3198 // Linux mmap allows caller to pass an address as hint; give it a try first, 3199 // if kernel honors the hint then we can return immediately. 3200 char * addr = anon_mmap(requested_addr, bytes, false); 3201 if (addr == requested_addr) { 3202 return requested_addr; 3203 } 3204 3205 if (addr != NULL) { 3206 // mmap() is successful but it fails to reserve at the requested address 3207 anon_munmap(addr, bytes); 3208 } 3209 3210 int i; 3211 for (i = 0; i < max_tries; ++i) { 3212 base[i] = reserve_memory(bytes); 3213 3214 if (base[i] != NULL) { 3215 // Is this the block we wanted? 3216 if (base[i] == requested_addr) { 3217 size[i] = bytes; 3218 break; 3219 } 3220 3221 // Does this overlap the block we wanted? Give back the overlapped 3222 // parts and try again. 3223 3224 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3225 if (top_overlap >= 0 && top_overlap < bytes) { 3226 unmap_memory(base[i], top_overlap); 3227 base[i] += top_overlap; 3228 size[i] = bytes - top_overlap; 3229 } else { 3230 size_t bottom_overlap = base[i] + bytes - requested_addr; 3231 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3232 unmap_memory(requested_addr, bottom_overlap); 3233 size[i] = bytes - bottom_overlap; 3234 } else { 3235 size[i] = bytes; 3236 } 3237 } 3238 } 3239 } 3240 3241 // Give back the unused reserved pieces. 3242 3243 for (int j = 0; j < i; ++j) { 3244 if (base[j] != NULL) { 3245 unmap_memory(base[j], size[j]); 3246 } 3247 } 3248 3249 if (i < max_tries) { 3250 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3251 return requested_addr; 3252 } else { 3253 _highest_vm_reserved_address = old_highest; 3254 return NULL; 3255 } 3256} 3257 3258size_t os::read(int fd, void *buf, unsigned int nBytes) { 3259 return ::read(fd, buf, nBytes); 3260} 3261 3262// TODO-FIXME: reconcile Solaris' os::sleep with the linux variation. 3263// Solaris uses poll(), linux uses park(). 3264// Poll() is likely a better choice, assuming that Thread.interrupt() 3265// generates a SIGUSRx signal. Note that SIGUSR1 can interfere with 3266// SIGSEGV, see 4355769. 3267 3268int os::sleep(Thread* thread, jlong millis, bool interruptible) { 3269 assert(thread == Thread::current(), "thread consistency check"); 3270 3271 ParkEvent * const slp = thread->_SleepEvent ; 3272 slp->reset() ; 3273 OrderAccess::fence() ; 3274 3275 if (interruptible) { 3276 jlong prevtime = javaTimeNanos(); 3277 3278 for (;;) { 3279 if (os::is_interrupted(thread, true)) { 3280 return OS_INTRPT; 3281 } 3282 3283 jlong newtime = javaTimeNanos(); 3284 3285 if (newtime - prevtime < 0) { 3286 // time moving backwards, should only happen if no monotonic clock 3287 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3288 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3289 } else { 3290 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3291 } 3292 3293 if(millis <= 0) { 3294 return OS_OK; 3295 } 3296 3297 prevtime = newtime; 3298 3299 { 3300 assert(thread->is_Java_thread(), "sanity check"); 3301 JavaThread *jt = (JavaThread *) thread; 3302 ThreadBlockInVM tbivm(jt); 3303 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */); 3304 3305 jt->set_suspend_equivalent(); 3306 // cleared by handle_special_suspend_equivalent_condition() or 3307 // java_suspend_self() via check_and_wait_while_suspended() 3308 3309 slp->park(millis); 3310 3311 // were we externally suspended while we were waiting? 3312 jt->check_and_wait_while_suspended(); 3313 } 3314 } 3315 } else { 3316 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 3317 jlong prevtime = javaTimeNanos(); 3318 3319 for (;;) { 3320 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on 3321 // the 1st iteration ... 3322 jlong newtime = javaTimeNanos(); 3323 3324 if (newtime - prevtime < 0) { 3325 // time moving backwards, should only happen if no monotonic clock 3326 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3327 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3328 } else { 3329 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3330 } 3331 3332 if(millis <= 0) break ; 3333 3334 prevtime = newtime; 3335 slp->park(millis); 3336 } 3337 return OS_OK ; 3338 } 3339} 3340 3341int os::naked_sleep() { 3342 // %% make the sleep time an integer flag. for now use 1 millisec. 3343 return os::sleep(Thread::current(), 1, false); 3344} 3345 3346// Sleep forever; naked call to OS-specific sleep; use with CAUTION 3347void os::infinite_sleep() { 3348 while (true) { // sleep forever ... 3349 ::sleep(100); // ... 100 seconds at a time 3350 } 3351} 3352 3353// Used to convert frequent JVM_Yield() to nops 3354bool os::dont_yield() { 3355 return DontYieldALot; 3356} 3357 3358void os::yield() { 3359 sched_yield(); 3360} 3361 3362os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 3363 3364void os::yield_all(int attempts) { 3365 // Yields to all threads, including threads with lower priorities 3366 // Threads on Linux are all with same priority. The Solaris style 3367 // os::yield_all() with nanosleep(1ms) is not necessary. 3368 sched_yield(); 3369} 3370 3371// Called from the tight loops to possibly influence time-sharing heuristics 3372void os::loop_breaker(int attempts) { 3373 os::yield_all(attempts); 3374} 3375 3376//////////////////////////////////////////////////////////////////////////////// 3377// thread priority support 3378 3379// Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3380// only supports dynamic priority, static priority must be zero. For real-time 3381// applications, Linux supports SCHED_RR which allows static priority (1-99). 3382// However, for large multi-threaded applications, SCHED_RR is not only slower 3383// than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3384// of 5 runs - Sep 2005). 3385// 3386// The following code actually changes the niceness of kernel-thread/LWP. It 3387// has an assumption that setpriority() only modifies one kernel-thread/LWP, 3388// not the entire user process, and user level threads are 1:1 mapped to kernel 3389// threads. It has always been the case, but could change in the future. For 3390// this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3391// It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3392 3393int os::java_to_os_priority[CriticalPriority + 1] = { 3394 19, // 0 Entry should never be used 3395 3396 4, // 1 MinPriority 3397 3, // 2 3398 2, // 3 3399 3400 1, // 4 3401 0, // 5 NormPriority 3402 -1, // 6 3403 3404 -2, // 7 3405 -3, // 8 3406 -4, // 9 NearMaxPriority 3407 3408 -5, // 10 MaxPriority 3409 3410 -5 // 11 CriticalPriority 3411}; 3412 3413static int prio_init() { 3414 if (ThreadPriorityPolicy == 1) { 3415 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3416 // if effective uid is not root. Perhaps, a more elegant way of doing 3417 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3418 if (geteuid() != 0) { 3419 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3420 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3421 } 3422 ThreadPriorityPolicy = 0; 3423 } 3424 } 3425 if (UseCriticalJavaThreadPriority) { 3426 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3427 } 3428 return 0; 3429} 3430 3431OSReturn os::set_native_priority(Thread* thread, int newpri) { 3432 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 3433 3434 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3435 return (ret == 0) ? OS_OK : OS_ERR; 3436} 3437 3438OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3439 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3440 *priority_ptr = java_to_os_priority[NormPriority]; 3441 return OS_OK; 3442 } 3443 3444 errno = 0; 3445 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3446 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3447} 3448 3449// Hint to the underlying OS that a task switch would not be good. 3450// Void return because it's a hint and can fail. 3451void os::hint_no_preempt() {} 3452 3453//////////////////////////////////////////////////////////////////////////////// 3454// suspend/resume support 3455 3456// the low-level signal-based suspend/resume support is a remnant from the 3457// old VM-suspension that used to be for java-suspension, safepoints etc, 3458// within hotspot. Now there is a single use-case for this: 3459// - calling get_thread_pc() on the VMThread by the flat-profiler task 3460// that runs in the watcher thread. 3461// The remaining code is greatly simplified from the more general suspension 3462// code that used to be used. 3463// 3464// The protocol is quite simple: 3465// - suspend: 3466// - sends a signal to the target thread 3467// - polls the suspend state of the osthread using a yield loop 3468// - target thread signal handler (SR_handler) sets suspend state 3469// and blocks in sigsuspend until continued 3470// - resume: 3471// - sets target osthread state to continue 3472// - sends signal to end the sigsuspend loop in the SR_handler 3473// 3474// Note that the SR_lock plays no role in this suspend/resume protocol. 3475// 3476 3477static void resume_clear_context(OSThread *osthread) { 3478 osthread->set_ucontext(NULL); 3479 osthread->set_siginfo(NULL); 3480 3481 // notify the suspend action is completed, we have now resumed 3482 osthread->sr.clear_suspended(); 3483} 3484 3485static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 3486 osthread->set_ucontext(context); 3487 osthread->set_siginfo(siginfo); 3488} 3489 3490// 3491// Handler function invoked when a thread's execution is suspended or 3492// resumed. We have to be careful that only async-safe functions are 3493// called here (Note: most pthread functions are not async safe and 3494// should be avoided.) 3495// 3496// Note: sigwait() is a more natural fit than sigsuspend() from an 3497// interface point of view, but sigwait() prevents the signal hander 3498// from being run. libpthread would get very confused by not having 3499// its signal handlers run and prevents sigwait()'s use with the 3500// mutex granting granting signal. 3501// 3502// Currently only ever called on the VMThread 3503// 3504static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3505 // Save and restore errno to avoid confusing native code with EINTR 3506 // after sigsuspend. 3507 int old_errno = errno; 3508 3509 Thread* thread = Thread::current(); 3510 OSThread* osthread = thread->osthread(); 3511 assert(thread->is_VM_thread(), "Must be VMThread"); 3512 // read current suspend action 3513 int action = osthread->sr.suspend_action(); 3514 if (action == SR_SUSPEND) { 3515 suspend_save_context(osthread, siginfo, context); 3516 3517 // Notify the suspend action is about to be completed. do_suspend() 3518 // waits until SR_SUSPENDED is set and then returns. We will wait 3519 // here for a resume signal and that completes the suspend-other 3520 // action. do_suspend/do_resume is always called as a pair from 3521 // the same thread - so there are no races 3522 3523 // notify the caller 3524 osthread->sr.set_suspended(); 3525 3526 sigset_t suspend_set; // signals for sigsuspend() 3527 3528 // get current set of blocked signals and unblock resume signal 3529 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3530 sigdelset(&suspend_set, SR_signum); 3531 3532 // wait here until we are resumed 3533 do { 3534 sigsuspend(&suspend_set); 3535 // ignore all returns until we get a resume signal 3536 } while (osthread->sr.suspend_action() != SR_CONTINUE); 3537 3538 resume_clear_context(osthread); 3539 3540 } else { 3541 assert(action == SR_CONTINUE, "unexpected sr action"); 3542 // nothing special to do - just leave the handler 3543 } 3544 3545 errno = old_errno; 3546} 3547 3548 3549static int SR_initialize() { 3550 struct sigaction act; 3551 char *s; 3552 /* Get signal number to use for suspend/resume */ 3553 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 3554 int sig = ::strtol(s, 0, 10); 3555 if (sig > 0 || sig < _NSIG) { 3556 SR_signum = sig; 3557 } 3558 } 3559 3560 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 3561 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 3562 3563 sigemptyset(&SR_sigset); 3564 sigaddset(&SR_sigset, SR_signum); 3565 3566 /* Set up signal handler for suspend/resume */ 3567 act.sa_flags = SA_RESTART|SA_SIGINFO; 3568 act.sa_handler = (void (*)(int)) SR_handler; 3569 3570 // SR_signum is blocked by default. 3571 // 4528190 - We also need to block pthread restart signal (32 on all 3572 // supported Linux platforms). Note that LinuxThreads need to block 3573 // this signal for all threads to work properly. So we don't have 3574 // to use hard-coded signal number when setting up the mask. 3575 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 3576 3577 if (sigaction(SR_signum, &act, 0) == -1) { 3578 return -1; 3579 } 3580 3581 // Save signal flag 3582 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 3583 return 0; 3584} 3585 3586static int SR_finalize() { 3587 return 0; 3588} 3589 3590 3591// returns true on success and false on error - really an error is fatal 3592// but this seems the normal response to library errors 3593static bool do_suspend(OSThread* osthread) { 3594 // mark as suspended and send signal 3595 osthread->sr.set_suspend_action(SR_SUSPEND); 3596 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3597 assert_status(status == 0, status, "pthread_kill"); 3598 3599 // check status and wait until notified of suspension 3600 if (status == 0) { 3601 for (int i = 0; !osthread->sr.is_suspended(); i++) { 3602 os::yield_all(i); 3603 } 3604 osthread->sr.set_suspend_action(SR_NONE); 3605 return true; 3606 } 3607 else { 3608 osthread->sr.set_suspend_action(SR_NONE); 3609 return false; 3610 } 3611} 3612 3613static void do_resume(OSThread* osthread) { 3614 assert(osthread->sr.is_suspended(), "thread should be suspended"); 3615 osthread->sr.set_suspend_action(SR_CONTINUE); 3616 3617 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3618 assert_status(status == 0, status, "pthread_kill"); 3619 // check status and wait unit notified of resumption 3620 if (status == 0) { 3621 for (int i = 0; osthread->sr.is_suspended(); i++) { 3622 os::yield_all(i); 3623 } 3624 } 3625 osthread->sr.set_suspend_action(SR_NONE); 3626} 3627 3628//////////////////////////////////////////////////////////////////////////////// 3629// interrupt support 3630 3631void os::interrupt(Thread* thread) { 3632 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3633 "possibility of dangling Thread pointer"); 3634 3635 OSThread* osthread = thread->osthread(); 3636 3637 if (!osthread->interrupted()) { 3638 osthread->set_interrupted(true); 3639 // More than one thread can get here with the same value of osthread, 3640 // resulting in multiple notifications. We do, however, want the store 3641 // to interrupted() to be visible to other threads before we execute unpark(). 3642 OrderAccess::fence(); 3643 ParkEvent * const slp = thread->_SleepEvent ; 3644 if (slp != NULL) slp->unpark() ; 3645 } 3646 3647 // For JSR166. Unpark even if interrupt status already was set 3648 if (thread->is_Java_thread()) 3649 ((JavaThread*)thread)->parker()->unpark(); 3650 3651 ParkEvent * ev = thread->_ParkEvent ; 3652 if (ev != NULL) ev->unpark() ; 3653 3654} 3655 3656bool os::is_interrupted(Thread* thread, bool clear_interrupted) { 3657 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3658 "possibility of dangling Thread pointer"); 3659 3660 OSThread* osthread = thread->osthread(); 3661 3662 bool interrupted = osthread->interrupted(); 3663 3664 if (interrupted && clear_interrupted) { 3665 osthread->set_interrupted(false); 3666 // consider thread->_SleepEvent->reset() ... optional optimization 3667 } 3668 3669 return interrupted; 3670} 3671 3672/////////////////////////////////////////////////////////////////////////////////// 3673// signal handling (except suspend/resume) 3674 3675// This routine may be used by user applications as a "hook" to catch signals. 3676// The user-defined signal handler must pass unrecognized signals to this 3677// routine, and if it returns true (non-zero), then the signal handler must 3678// return immediately. If the flag "abort_if_unrecognized" is true, then this 3679// routine will never retun false (zero), but instead will execute a VM panic 3680// routine kill the process. 3681// 3682// If this routine returns false, it is OK to call it again. This allows 3683// the user-defined signal handler to perform checks either before or after 3684// the VM performs its own checks. Naturally, the user code would be making 3685// a serious error if it tried to handle an exception (such as a null check 3686// or breakpoint) that the VM was generating for its own correct operation. 3687// 3688// This routine may recognize any of the following kinds of signals: 3689// SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 3690// It should be consulted by handlers for any of those signals. 3691// 3692// The caller of this routine must pass in the three arguments supplied 3693// to the function referred to in the "sa_sigaction" (not the "sa_handler") 3694// field of the structure passed to sigaction(). This routine assumes that 3695// the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 3696// 3697// Note that the VM will print warnings if it detects conflicting signal 3698// handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 3699// 3700extern "C" JNIEXPORT int 3701JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 3702 void* ucontext, int abort_if_unrecognized); 3703 3704void signalHandler(int sig, siginfo_t* info, void* uc) { 3705 assert(info != NULL && uc != NULL, "it must be old kernel"); 3706 JVM_handle_linux_signal(sig, info, uc, true); 3707} 3708 3709 3710// This boolean allows users to forward their own non-matching signals 3711// to JVM_handle_linux_signal, harmlessly. 3712bool os::Linux::signal_handlers_are_installed = false; 3713 3714// For signal-chaining 3715struct sigaction os::Linux::sigact[MAXSIGNUM]; 3716unsigned int os::Linux::sigs = 0; 3717bool os::Linux::libjsig_is_loaded = false; 3718typedef struct sigaction *(*get_signal_t)(int); 3719get_signal_t os::Linux::get_signal_action = NULL; 3720 3721struct sigaction* os::Linux::get_chained_signal_action(int sig) { 3722 struct sigaction *actp = NULL; 3723 3724 if (libjsig_is_loaded) { 3725 // Retrieve the old signal handler from libjsig 3726 actp = (*get_signal_action)(sig); 3727 } 3728 if (actp == NULL) { 3729 // Retrieve the preinstalled signal handler from jvm 3730 actp = get_preinstalled_handler(sig); 3731 } 3732 3733 return actp; 3734} 3735 3736static bool call_chained_handler(struct sigaction *actp, int sig, 3737 siginfo_t *siginfo, void *context) { 3738 // Call the old signal handler 3739 if (actp->sa_handler == SIG_DFL) { 3740 // It's more reasonable to let jvm treat it as an unexpected exception 3741 // instead of taking the default action. 3742 return false; 3743 } else if (actp->sa_handler != SIG_IGN) { 3744 if ((actp->sa_flags & SA_NODEFER) == 0) { 3745 // automaticlly block the signal 3746 sigaddset(&(actp->sa_mask), sig); 3747 } 3748 3749 sa_handler_t hand; 3750 sa_sigaction_t sa; 3751 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 3752 // retrieve the chained handler 3753 if (siginfo_flag_set) { 3754 sa = actp->sa_sigaction; 3755 } else { 3756 hand = actp->sa_handler; 3757 } 3758 3759 if ((actp->sa_flags & SA_RESETHAND) != 0) { 3760 actp->sa_handler = SIG_DFL; 3761 } 3762 3763 // try to honor the signal mask 3764 sigset_t oset; 3765 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 3766 3767 // call into the chained handler 3768 if (siginfo_flag_set) { 3769 (*sa)(sig, siginfo, context); 3770 } else { 3771 (*hand)(sig); 3772 } 3773 3774 // restore the signal mask 3775 pthread_sigmask(SIG_SETMASK, &oset, 0); 3776 } 3777 // Tell jvm's signal handler the signal is taken care of. 3778 return true; 3779} 3780 3781bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 3782 bool chained = false; 3783 // signal-chaining 3784 if (UseSignalChaining) { 3785 struct sigaction *actp = get_chained_signal_action(sig); 3786 if (actp != NULL) { 3787 chained = call_chained_handler(actp, sig, siginfo, context); 3788 } 3789 } 3790 return chained; 3791} 3792 3793struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 3794 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 3795 return &sigact[sig]; 3796 } 3797 return NULL; 3798} 3799 3800void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 3801 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3802 sigact[sig] = oldAct; 3803 sigs |= (unsigned int)1 << sig; 3804} 3805 3806// for diagnostic 3807int os::Linux::sigflags[MAXSIGNUM]; 3808 3809int os::Linux::get_our_sigflags(int sig) { 3810 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3811 return sigflags[sig]; 3812} 3813 3814void os::Linux::set_our_sigflags(int sig, int flags) { 3815 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3816 sigflags[sig] = flags; 3817} 3818 3819void os::Linux::set_signal_handler(int sig, bool set_installed) { 3820 // Check for overwrite. 3821 struct sigaction oldAct; 3822 sigaction(sig, (struct sigaction*)NULL, &oldAct); 3823 3824 void* oldhand = oldAct.sa_sigaction 3825 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3826 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3827 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 3828 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 3829 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 3830 if (AllowUserSignalHandlers || !set_installed) { 3831 // Do not overwrite; user takes responsibility to forward to us. 3832 return; 3833 } else if (UseSignalChaining) { 3834 // save the old handler in jvm 3835 save_preinstalled_handler(sig, oldAct); 3836 // libjsig also interposes the sigaction() call below and saves the 3837 // old sigaction on it own. 3838 } else { 3839 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 3840 "%#lx for signal %d.", (long)oldhand, sig)); 3841 } 3842 } 3843 3844 struct sigaction sigAct; 3845 sigfillset(&(sigAct.sa_mask)); 3846 sigAct.sa_handler = SIG_DFL; 3847 if (!set_installed) { 3848 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3849 } else { 3850 sigAct.sa_sigaction = signalHandler; 3851 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3852 } 3853 // Save flags, which are set by ours 3854 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3855 sigflags[sig] = sigAct.sa_flags; 3856 3857 int ret = sigaction(sig, &sigAct, &oldAct); 3858 assert(ret == 0, "check"); 3859 3860 void* oldhand2 = oldAct.sa_sigaction 3861 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3862 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3863 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 3864} 3865 3866// install signal handlers for signals that HotSpot needs to 3867// handle in order to support Java-level exception handling. 3868 3869void os::Linux::install_signal_handlers() { 3870 if (!signal_handlers_are_installed) { 3871 signal_handlers_are_installed = true; 3872 3873 // signal-chaining 3874 typedef void (*signal_setting_t)(); 3875 signal_setting_t begin_signal_setting = NULL; 3876 signal_setting_t end_signal_setting = NULL; 3877 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3878 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 3879 if (begin_signal_setting != NULL) { 3880 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3881 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 3882 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 3883 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 3884 libjsig_is_loaded = true; 3885 assert(UseSignalChaining, "should enable signal-chaining"); 3886 } 3887 if (libjsig_is_loaded) { 3888 // Tell libjsig jvm is setting signal handlers 3889 (*begin_signal_setting)(); 3890 } 3891 3892 set_signal_handler(SIGSEGV, true); 3893 set_signal_handler(SIGPIPE, true); 3894 set_signal_handler(SIGBUS, true); 3895 set_signal_handler(SIGILL, true); 3896 set_signal_handler(SIGFPE, true); 3897 set_signal_handler(SIGXFSZ, true); 3898 3899 if (libjsig_is_loaded) { 3900 // Tell libjsig jvm finishes setting signal handlers 3901 (*end_signal_setting)(); 3902 } 3903 3904 // We don't activate signal checker if libjsig is in place, we trust ourselves 3905 // and if UserSignalHandler is installed all bets are off. 3906 // Log that signal checking is off only if -verbose:jni is specified. 3907 if (CheckJNICalls) { 3908 if (libjsig_is_loaded) { 3909 if (PrintJNIResolving) { 3910 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 3911 } 3912 check_signals = false; 3913 } 3914 if (AllowUserSignalHandlers) { 3915 if (PrintJNIResolving) { 3916 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 3917 } 3918 check_signals = false; 3919 } 3920 } 3921 } 3922} 3923 3924// This is the fastest way to get thread cpu time on Linux. 3925// Returns cpu time (user+sys) for any thread, not only for current. 3926// POSIX compliant clocks are implemented in the kernels 2.6.16+. 3927// It might work on 2.6.10+ with a special kernel/glibc patch. 3928// For reference, please, see IEEE Std 1003.1-2004: 3929// http://www.unix.org/single_unix_specification 3930 3931jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 3932 struct timespec tp; 3933 int rc = os::Linux::clock_gettime(clockid, &tp); 3934 assert(rc == 0, "clock_gettime is expected to return 0 code"); 3935 3936 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 3937} 3938 3939///// 3940// glibc on Linux platform uses non-documented flag 3941// to indicate, that some special sort of signal 3942// trampoline is used. 3943// We will never set this flag, and we should 3944// ignore this flag in our diagnostic 3945#ifdef SIGNIFICANT_SIGNAL_MASK 3946#undef SIGNIFICANT_SIGNAL_MASK 3947#endif 3948#define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 3949 3950static const char* get_signal_handler_name(address handler, 3951 char* buf, int buflen) { 3952 int offset; 3953 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 3954 if (found) { 3955 // skip directory names 3956 const char *p1, *p2; 3957 p1 = buf; 3958 size_t len = strlen(os::file_separator()); 3959 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 3960 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 3961 } else { 3962 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 3963 } 3964 return buf; 3965} 3966 3967static void print_signal_handler(outputStream* st, int sig, 3968 char* buf, size_t buflen) { 3969 struct sigaction sa; 3970 3971 sigaction(sig, NULL, &sa); 3972 3973 // See comment for SIGNIFICANT_SIGNAL_MASK define 3974 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 3975 3976 st->print("%s: ", os::exception_name(sig, buf, buflen)); 3977 3978 address handler = (sa.sa_flags & SA_SIGINFO) 3979 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 3980 : CAST_FROM_FN_PTR(address, sa.sa_handler); 3981 3982 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 3983 st->print("SIG_DFL"); 3984 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 3985 st->print("SIG_IGN"); 3986 } else { 3987 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 3988 } 3989 3990 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask); 3991 3992 address rh = VMError::get_resetted_sighandler(sig); 3993 // May be, handler was resetted by VMError? 3994 if(rh != NULL) { 3995 handler = rh; 3996 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 3997 } 3998 3999 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags); 4000 4001 // Check: is it our handler? 4002 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4003 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4004 // It is our signal handler 4005 // check for flags, reset system-used one! 4006 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4007 st->print( 4008 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4009 os::Linux::get_our_sigflags(sig)); 4010 } 4011 } 4012 st->cr(); 4013} 4014 4015 4016#define DO_SIGNAL_CHECK(sig) \ 4017 if (!sigismember(&check_signal_done, sig)) \ 4018 os::Linux::check_signal_handler(sig) 4019 4020// This method is a periodic task to check for misbehaving JNI applications 4021// under CheckJNI, we can add any periodic checks here 4022 4023void os::run_periodic_checks() { 4024 4025 if (check_signals == false) return; 4026 4027 // SEGV and BUS if overridden could potentially prevent 4028 // generation of hs*.log in the event of a crash, debugging 4029 // such a case can be very challenging, so we absolutely 4030 // check the following for a good measure: 4031 DO_SIGNAL_CHECK(SIGSEGV); 4032 DO_SIGNAL_CHECK(SIGILL); 4033 DO_SIGNAL_CHECK(SIGFPE); 4034 DO_SIGNAL_CHECK(SIGBUS); 4035 DO_SIGNAL_CHECK(SIGPIPE); 4036 DO_SIGNAL_CHECK(SIGXFSZ); 4037 4038 4039 // ReduceSignalUsage allows the user to override these handlers 4040 // see comments at the very top and jvm_solaris.h 4041 if (!ReduceSignalUsage) { 4042 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4043 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4044 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4045 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4046 } 4047 4048 DO_SIGNAL_CHECK(SR_signum); 4049 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4050} 4051 4052typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4053 4054static os_sigaction_t os_sigaction = NULL; 4055 4056void os::Linux::check_signal_handler(int sig) { 4057 char buf[O_BUFLEN]; 4058 address jvmHandler = NULL; 4059 4060 4061 struct sigaction act; 4062 if (os_sigaction == NULL) { 4063 // only trust the default sigaction, in case it has been interposed 4064 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4065 if (os_sigaction == NULL) return; 4066 } 4067 4068 os_sigaction(sig, (struct sigaction*)NULL, &act); 4069 4070 4071 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4072 4073 address thisHandler = (act.sa_flags & SA_SIGINFO) 4074 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4075 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 4076 4077 4078 switch(sig) { 4079 case SIGSEGV: 4080 case SIGBUS: 4081 case SIGFPE: 4082 case SIGPIPE: 4083 case SIGILL: 4084 case SIGXFSZ: 4085 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4086 break; 4087 4088 case SHUTDOWN1_SIGNAL: 4089 case SHUTDOWN2_SIGNAL: 4090 case SHUTDOWN3_SIGNAL: 4091 case BREAK_SIGNAL: 4092 jvmHandler = (address)user_handler(); 4093 break; 4094 4095 case INTERRUPT_SIGNAL: 4096 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4097 break; 4098 4099 default: 4100 if (sig == SR_signum) { 4101 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4102 } else { 4103 return; 4104 } 4105 break; 4106 } 4107 4108 if (thisHandler != jvmHandler) { 4109 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4110 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4111 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4112 // No need to check this sig any longer 4113 sigaddset(&check_signal_done, sig); 4114 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4115 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4116 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4117 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4118 // No need to check this sig any longer 4119 sigaddset(&check_signal_done, sig); 4120 } 4121 4122 // Dump all the signal 4123 if (sigismember(&check_signal_done, sig)) { 4124 print_signal_handlers(tty, buf, O_BUFLEN); 4125 } 4126} 4127 4128extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 4129 4130extern bool signal_name(int signo, char* buf, size_t len); 4131 4132const char* os::exception_name(int exception_code, char* buf, size_t size) { 4133 if (0 < exception_code && exception_code <= SIGRTMAX) { 4134 // signal 4135 if (!signal_name(exception_code, buf, size)) { 4136 jio_snprintf(buf, size, "SIG%d", exception_code); 4137 } 4138 return buf; 4139 } else { 4140 return NULL; 4141 } 4142} 4143 4144// this is called _before_ the most of global arguments have been parsed 4145void os::init(void) { 4146 char dummy; /* used to get a guess on initial stack address */ 4147// first_hrtime = gethrtime(); 4148 4149 // With LinuxThreads the JavaMain thread pid (primordial thread) 4150 // is different than the pid of the java launcher thread. 4151 // So, on Linux, the launcher thread pid is passed to the VM 4152 // via the sun.java.launcher.pid property. 4153 // Use this property instead of getpid() if it was correctly passed. 4154 // See bug 6351349. 4155 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4156 4157 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4158 4159 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4160 4161 init_random(1234567); 4162 4163 ThreadCritical::initialize(); 4164 4165 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4166 if (Linux::page_size() == -1) { 4167 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4168 strerror(errno))); 4169 } 4170 init_page_sizes((size_t) Linux::page_size()); 4171 4172 Linux::initialize_system_info(); 4173 4174 // main_thread points to the aboriginal thread 4175 Linux::_main_thread = pthread_self(); 4176 4177 Linux::clock_init(); 4178 initial_time_count = os::elapsed_counter(); 4179 pthread_mutex_init(&dl_mutex, NULL); 4180} 4181 4182// To install functions for atexit system call 4183extern "C" { 4184 static void perfMemory_exit_helper() { 4185 perfMemory_exit(); 4186 } 4187} 4188 4189// this is called _after_ the global arguments have been parsed 4190jint os::init_2(void) 4191{ 4192 Linux::fast_thread_clock_init(); 4193 4194 // Allocate a single page and mark it as readable for safepoint polling 4195 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4196 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 4197 4198 os::set_polling_page( polling_page ); 4199 4200#ifndef PRODUCT 4201 if(Verbose && PrintMiscellaneous) 4202 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 4203#endif 4204 4205 if (!UseMembar) { 4206 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4207 guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page"); 4208 os::set_memory_serialize_page( mem_serialize_page ); 4209 4210#ifndef PRODUCT 4211 if(Verbose && PrintMiscellaneous) 4212 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 4213#endif 4214 } 4215 4216 os::large_page_init(); 4217 4218 // initialize suspend/resume support - must do this before signal_sets_init() 4219 if (SR_initialize() != 0) { 4220 perror("SR_initialize failed"); 4221 return JNI_ERR; 4222 } 4223 4224 Linux::signal_sets_init(); 4225 Linux::install_signal_handlers(); 4226 4227 // Check minimum allowable stack size for thread creation and to initialize 4228 // the java system classes, including StackOverflowError - depends on page 4229 // size. Add a page for compiler2 recursion in main thread. 4230 // Add in 2*BytesPerWord times page size to account for VM stack during 4231 // class initialization depending on 32 or 64 bit VM. 4232 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4233 (size_t)(StackYellowPages+StackRedPages+StackShadowPages+ 4234 2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::page_size()); 4235 4236 size_t threadStackSizeInBytes = ThreadStackSize * K; 4237 if (threadStackSizeInBytes != 0 && 4238 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4239 tty->print_cr("\nThe stack size specified is too small, " 4240 "Specify at least %dk", 4241 os::Linux::min_stack_allowed/ K); 4242 return JNI_ERR; 4243 } 4244 4245 // Make the stack size a multiple of the page size so that 4246 // the yellow/red zones can be guarded. 4247 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4248 vm_page_size())); 4249 4250 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4251 4252 Linux::libpthread_init(); 4253 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4254 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4255 Linux::glibc_version(), Linux::libpthread_version(), 4256 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4257 } 4258 4259 if (UseNUMA) { 4260 if (!Linux::libnuma_init()) { 4261 UseNUMA = false; 4262 } else { 4263 if ((Linux::numa_max_node() < 1)) { 4264 // There's only one node(they start from 0), disable NUMA. 4265 UseNUMA = false; 4266 } 4267 } 4268 // With SHM large pages we cannot uncommit a page, so there's not way 4269 // we can make the adaptive lgrp chunk resizing work. If the user specified 4270 // both UseNUMA and UseLargePages (or UseSHM) on the command line - warn and 4271 // disable adaptive resizing. 4272 if (UseNUMA && UseLargePages && UseSHM) { 4273 if (!FLAG_IS_DEFAULT(UseNUMA)) { 4274 if (FLAG_IS_DEFAULT(UseLargePages) && FLAG_IS_DEFAULT(UseSHM)) { 4275 UseLargePages = false; 4276 } else { 4277 warning("UseNUMA is not fully compatible with SHM large pages, disabling adaptive resizing"); 4278 UseAdaptiveSizePolicy = false; 4279 UseAdaptiveNUMAChunkSizing = false; 4280 } 4281 } else { 4282 UseNUMA = false; 4283 } 4284 } 4285 if (!UseNUMA && ForceNUMA) { 4286 UseNUMA = true; 4287 } 4288 } 4289 4290 if (MaxFDLimit) { 4291 // set the number of file descriptors to max. print out error 4292 // if getrlimit/setrlimit fails but continue regardless. 4293 struct rlimit nbr_files; 4294 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4295 if (status != 0) { 4296 if (PrintMiscellaneous && (Verbose || WizardMode)) 4297 perror("os::init_2 getrlimit failed"); 4298 } else { 4299 nbr_files.rlim_cur = nbr_files.rlim_max; 4300 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4301 if (status != 0) { 4302 if (PrintMiscellaneous && (Verbose || WizardMode)) 4303 perror("os::init_2 setrlimit failed"); 4304 } 4305 } 4306 } 4307 4308 // Initialize lock used to serialize thread creation (see os::create_thread) 4309 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4310 4311 // at-exit methods are called in the reverse order of their registration. 4312 // atexit functions are called on return from main or as a result of a 4313 // call to exit(3C). There can be only 32 of these functions registered 4314 // and atexit() does not set errno. 4315 4316 if (PerfAllowAtExitRegistration) { 4317 // only register atexit functions if PerfAllowAtExitRegistration is set. 4318 // atexit functions can be delayed until process exit time, which 4319 // can be problematic for embedded VM situations. Embedded VMs should 4320 // call DestroyJavaVM() to assure that VM resources are released. 4321 4322 // note: perfMemory_exit_helper atexit function may be removed in 4323 // the future if the appropriate cleanup code can be added to the 4324 // VM_Exit VMOperation's doit method. 4325 if (atexit(perfMemory_exit_helper) != 0) { 4326 warning("os::init2 atexit(perfMemory_exit_helper) failed"); 4327 } 4328 } 4329 4330 // initialize thread priority policy 4331 prio_init(); 4332 4333 return JNI_OK; 4334} 4335 4336// this is called at the end of vm_initialization 4337void os::init_3(void) 4338{ 4339#ifdef JAVASE_EMBEDDED 4340 // Start the MemNotifyThread 4341 if (LowMemoryProtection) { 4342 MemNotifyThread::start(); 4343 } 4344 return; 4345#endif 4346} 4347 4348// Mark the polling page as unreadable 4349void os::make_polling_page_unreadable(void) { 4350 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 4351 fatal("Could not disable polling page"); 4352}; 4353 4354// Mark the polling page as readable 4355void os::make_polling_page_readable(void) { 4356 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4357 fatal("Could not enable polling page"); 4358 } 4359}; 4360 4361int os::active_processor_count() { 4362 // Linux doesn't yet have a (official) notion of processor sets, 4363 // so just return the number of online processors. 4364 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4365 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4366 return online_cpus; 4367} 4368 4369void os::set_native_thread_name(const char *name) { 4370 // Not yet implemented. 4371 return; 4372} 4373 4374bool os::distribute_processes(uint length, uint* distribution) { 4375 // Not yet implemented. 4376 return false; 4377} 4378 4379bool os::bind_to_processor(uint processor_id) { 4380 // Not yet implemented. 4381 return false; 4382} 4383 4384/// 4385 4386// Suspends the target using the signal mechanism and then grabs the PC before 4387// resuming the target. Used by the flat-profiler only 4388ExtendedPC os::get_thread_pc(Thread* thread) { 4389 // Make sure that it is called by the watcher for the VMThread 4390 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4391 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4392 4393 ExtendedPC epc; 4394 4395 OSThread* osthread = thread->osthread(); 4396 if (do_suspend(osthread)) { 4397 if (osthread->ucontext() != NULL) { 4398 epc = os::Linux::ucontext_get_pc(osthread->ucontext()); 4399 } else { 4400 // NULL context is unexpected, double-check this is the VMThread 4401 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4402 } 4403 do_resume(osthread); 4404 } 4405 // failure means pthread_kill failed for some reason - arguably this is 4406 // a fatal problem, but such problems are ignored elsewhere 4407 4408 return epc; 4409} 4410 4411int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 4412{ 4413 if (is_NPTL()) { 4414 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4415 } else { 4416#ifndef IA64 4417 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4418 // word back to default 64bit precision if condvar is signaled. Java 4419 // wants 53bit precision. Save and restore current value. 4420 int fpu = get_fpu_control_word(); 4421#endif // IA64 4422 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4423#ifndef IA64 4424 set_fpu_control_word(fpu); 4425#endif // IA64 4426 return status; 4427 } 4428} 4429 4430//////////////////////////////////////////////////////////////////////////////// 4431// debug support 4432 4433static address same_page(address x, address y) { 4434 int page_bits = -os::vm_page_size(); 4435 if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits)) 4436 return x; 4437 else if (x > y) 4438 return (address)(intptr_t(y) | ~page_bits) + 1; 4439 else 4440 return (address)(intptr_t(y) & page_bits); 4441} 4442 4443bool os::find(address addr, outputStream* st) { 4444 Dl_info dlinfo; 4445 memset(&dlinfo, 0, sizeof(dlinfo)); 4446 if (dladdr(addr, &dlinfo)) { 4447 st->print(PTR_FORMAT ": ", addr); 4448 if (dlinfo.dli_sname != NULL) { 4449 st->print("%s+%#x", dlinfo.dli_sname, 4450 addr - (intptr_t)dlinfo.dli_saddr); 4451 } else if (dlinfo.dli_fname) { 4452 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4453 } else { 4454 st->print("<absolute address>"); 4455 } 4456 if (dlinfo.dli_fname) { 4457 st->print(" in %s", dlinfo.dli_fname); 4458 } 4459 if (dlinfo.dli_fbase) { 4460 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4461 } 4462 st->cr(); 4463 4464 if (Verbose) { 4465 // decode some bytes around the PC 4466 address begin = same_page(addr-40, addr); 4467 address end = same_page(addr+40, addr); 4468 address lowest = (address) dlinfo.dli_sname; 4469 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4470 if (begin < lowest) begin = lowest; 4471 Dl_info dlinfo2; 4472 if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr 4473 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 4474 end = (address) dlinfo2.dli_saddr; 4475 Disassembler::decode(begin, end, st); 4476 } 4477 return true; 4478 } 4479 return false; 4480} 4481 4482//////////////////////////////////////////////////////////////////////////////// 4483// misc 4484 4485// This does not do anything on Linux. This is basically a hook for being 4486// able to use structured exception handling (thread-local exception filters) 4487// on, e.g., Win32. 4488void 4489os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 4490 JavaCallArguments* args, Thread* thread) { 4491 f(value, method, args, thread); 4492} 4493 4494void os::print_statistics() { 4495} 4496 4497int os::message_box(const char* title, const char* message) { 4498 int i; 4499 fdStream err(defaultStream::error_fd()); 4500 for (i = 0; i < 78; i++) err.print_raw("="); 4501 err.cr(); 4502 err.print_raw_cr(title); 4503 for (i = 0; i < 78; i++) err.print_raw("-"); 4504 err.cr(); 4505 err.print_raw_cr(message); 4506 for (i = 0; i < 78; i++) err.print_raw("="); 4507 err.cr(); 4508 4509 char buf[16]; 4510 // Prevent process from exiting upon "read error" without consuming all CPU 4511 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 4512 4513 return buf[0] == 'y' || buf[0] == 'Y'; 4514} 4515 4516int os::stat(const char *path, struct stat *sbuf) { 4517 char pathbuf[MAX_PATH]; 4518 if (strlen(path) > MAX_PATH - 1) { 4519 errno = ENAMETOOLONG; 4520 return -1; 4521 } 4522 os::native_path(strcpy(pathbuf, path)); 4523 return ::stat(pathbuf, sbuf); 4524} 4525 4526bool os::check_heap(bool force) { 4527 return true; 4528} 4529 4530int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 4531 return ::vsnprintf(buf, count, format, args); 4532} 4533 4534// Is a (classpath) directory empty? 4535bool os::dir_is_empty(const char* path) { 4536 DIR *dir = NULL; 4537 struct dirent *ptr; 4538 4539 dir = opendir(path); 4540 if (dir == NULL) return true; 4541 4542 /* Scan the directory */ 4543 bool result = true; 4544 char buf[sizeof(struct dirent) + MAX_PATH]; 4545 while (result && (ptr = ::readdir(dir)) != NULL) { 4546 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 4547 result = false; 4548 } 4549 } 4550 closedir(dir); 4551 return result; 4552} 4553 4554// This code originates from JDK's sysOpen and open64_w 4555// from src/solaris/hpi/src/system_md.c 4556 4557#ifndef O_DELETE 4558#define O_DELETE 0x10000 4559#endif 4560 4561// Open a file. Unlink the file immediately after open returns 4562// if the specified oflag has the O_DELETE flag set. 4563// O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c 4564 4565int os::open(const char *path, int oflag, int mode) { 4566 4567 if (strlen(path) > MAX_PATH - 1) { 4568 errno = ENAMETOOLONG; 4569 return -1; 4570 } 4571 int fd; 4572 int o_delete = (oflag & O_DELETE); 4573 oflag = oflag & ~O_DELETE; 4574 4575 fd = ::open64(path, oflag, mode); 4576 if (fd == -1) return -1; 4577 4578 //If the open succeeded, the file might still be a directory 4579 { 4580 struct stat64 buf64; 4581 int ret = ::fstat64(fd, &buf64); 4582 int st_mode = buf64.st_mode; 4583 4584 if (ret != -1) { 4585 if ((st_mode & S_IFMT) == S_IFDIR) { 4586 errno = EISDIR; 4587 ::close(fd); 4588 return -1; 4589 } 4590 } else { 4591 ::close(fd); 4592 return -1; 4593 } 4594 } 4595 4596 /* 4597 * All file descriptors that are opened in the JVM and not 4598 * specifically destined for a subprocess should have the 4599 * close-on-exec flag set. If we don't set it, then careless 3rd 4600 * party native code might fork and exec without closing all 4601 * appropriate file descriptors (e.g. as we do in closeDescriptors in 4602 * UNIXProcess.c), and this in turn might: 4603 * 4604 * - cause end-of-file to fail to be detected on some file 4605 * descriptors, resulting in mysterious hangs, or 4606 * 4607 * - might cause an fopen in the subprocess to fail on a system 4608 * suffering from bug 1085341. 4609 * 4610 * (Yes, the default setting of the close-on-exec flag is a Unix 4611 * design flaw) 4612 * 4613 * See: 4614 * 1085341: 32-bit stdio routines should support file descriptors >255 4615 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed 4616 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 4617 */ 4618#ifdef FD_CLOEXEC 4619 { 4620 int flags = ::fcntl(fd, F_GETFD); 4621 if (flags != -1) 4622 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 4623 } 4624#endif 4625 4626 if (o_delete != 0) { 4627 ::unlink(path); 4628 } 4629 return fd; 4630} 4631 4632 4633// create binary file, rewriting existing file if required 4634int os::create_binary_file(const char* path, bool rewrite_existing) { 4635 int oflags = O_WRONLY | O_CREAT; 4636 if (!rewrite_existing) { 4637 oflags |= O_EXCL; 4638 } 4639 return ::open64(path, oflags, S_IREAD | S_IWRITE); 4640} 4641 4642// return current position of file pointer 4643jlong os::current_file_offset(int fd) { 4644 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 4645} 4646 4647// move file pointer to the specified offset 4648jlong os::seek_to_file_offset(int fd, jlong offset) { 4649 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 4650} 4651 4652// This code originates from JDK's sysAvailable 4653// from src/solaris/hpi/src/native_threads/src/sys_api_td.c 4654 4655int os::available(int fd, jlong *bytes) { 4656 jlong cur, end; 4657 int mode; 4658 struct stat64 buf64; 4659 4660 if (::fstat64(fd, &buf64) >= 0) { 4661 mode = buf64.st_mode; 4662 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 4663 /* 4664 * XXX: is the following call interruptible? If so, this might 4665 * need to go through the INTERRUPT_IO() wrapper as for other 4666 * blocking, interruptible calls in this file. 4667 */ 4668 int n; 4669 if (::ioctl(fd, FIONREAD, &n) >= 0) { 4670 *bytes = n; 4671 return 1; 4672 } 4673 } 4674 } 4675 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 4676 return 0; 4677 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 4678 return 0; 4679 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 4680 return 0; 4681 } 4682 *bytes = end - cur; 4683 return 1; 4684} 4685 4686int os::socket_available(int fd, jint *pbytes) { 4687 // Linux doc says EINTR not returned, unlike Solaris 4688 int ret = ::ioctl(fd, FIONREAD, pbytes); 4689 4690 //%% note ioctl can return 0 when successful, JVM_SocketAvailable 4691 // is expected to return 0 on failure and 1 on success to the jdk. 4692 return (ret < 0) ? 0 : 1; 4693} 4694 4695// Map a block of memory. 4696char* os::map_memory(int fd, const char* file_name, size_t file_offset, 4697 char *addr, size_t bytes, bool read_only, 4698 bool allow_exec) { 4699 int prot; 4700 int flags = MAP_PRIVATE; 4701 4702 if (read_only) { 4703 prot = PROT_READ; 4704 } else { 4705 prot = PROT_READ | PROT_WRITE; 4706 } 4707 4708 if (allow_exec) { 4709 prot |= PROT_EXEC; 4710 } 4711 4712 if (addr != NULL) { 4713 flags |= MAP_FIXED; 4714 } 4715 4716 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 4717 fd, file_offset); 4718 if (mapped_address == MAP_FAILED) { 4719 return NULL; 4720 } 4721 return mapped_address; 4722} 4723 4724 4725// Remap a block of memory. 4726char* os::remap_memory(int fd, const char* file_name, size_t file_offset, 4727 char *addr, size_t bytes, bool read_only, 4728 bool allow_exec) { 4729 // same as map_memory() on this OS 4730 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 4731 allow_exec); 4732} 4733 4734 4735// Unmap a block of memory. 4736bool os::unmap_memory(char* addr, size_t bytes) { 4737 return munmap(addr, bytes) == 0; 4738} 4739 4740static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 4741 4742static clockid_t thread_cpu_clockid(Thread* thread) { 4743 pthread_t tid = thread->osthread()->pthread_id(); 4744 clockid_t clockid; 4745 4746 // Get thread clockid 4747 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 4748 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 4749 return clockid; 4750} 4751 4752// current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 4753// are used by JVM M&M and JVMTI to get user+sys or user CPU time 4754// of a thread. 4755// 4756// current_thread_cpu_time() and thread_cpu_time(Thread*) returns 4757// the fast estimate available on the platform. 4758 4759jlong os::current_thread_cpu_time() { 4760 if (os::Linux::supports_fast_thread_cpu_time()) { 4761 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4762 } else { 4763 // return user + sys since the cost is the same 4764 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 4765 } 4766} 4767 4768jlong os::thread_cpu_time(Thread* thread) { 4769 // consistent with what current_thread_cpu_time() returns 4770 if (os::Linux::supports_fast_thread_cpu_time()) { 4771 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4772 } else { 4773 return slow_thread_cpu_time(thread, true /* user + sys */); 4774 } 4775} 4776 4777jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 4778 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4779 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4780 } else { 4781 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 4782 } 4783} 4784 4785jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4786 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4787 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4788 } else { 4789 return slow_thread_cpu_time(thread, user_sys_cpu_time); 4790 } 4791} 4792 4793// 4794// -1 on error. 4795// 4796 4797static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4798 static bool proc_pid_cpu_avail = true; 4799 static bool proc_task_unchecked = true; 4800 static const char *proc_stat_path = "/proc/%d/stat"; 4801 pid_t tid = thread->osthread()->thread_id(); 4802 int i; 4803 char *s; 4804 char stat[2048]; 4805 int statlen; 4806 char proc_name[64]; 4807 int count; 4808 long sys_time, user_time; 4809 char string[64]; 4810 char cdummy; 4811 int idummy; 4812 long ldummy; 4813 FILE *fp; 4814 4815 // We first try accessing /proc/<pid>/cpu since this is faster to 4816 // process. If this file is not present (linux kernels 2.5 and above) 4817 // then we open /proc/<pid>/stat. 4818 if ( proc_pid_cpu_avail ) { 4819 sprintf(proc_name, "/proc/%d/cpu", tid); 4820 fp = fopen(proc_name, "r"); 4821 if ( fp != NULL ) { 4822 count = fscanf( fp, "%s %lu %lu\n", string, &user_time, &sys_time); 4823 fclose(fp); 4824 if ( count != 3 ) return -1; 4825 4826 if (user_sys_cpu_time) { 4827 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 4828 } else { 4829 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 4830 } 4831 } 4832 else proc_pid_cpu_avail = false; 4833 } 4834 4835 // The /proc/<tid>/stat aggregates per-process usage on 4836 // new Linux kernels 2.6+ where NPTL is supported. 4837 // The /proc/self/task/<tid>/stat still has the per-thread usage. 4838 // See bug 6328462. 4839 // There can be no directory /proc/self/task on kernels 2.4 with NPTL 4840 // and possibly in some other cases, so we check its availability. 4841 if (proc_task_unchecked && os::Linux::is_NPTL()) { 4842 // This is executed only once 4843 proc_task_unchecked = false; 4844 fp = fopen("/proc/self/task", "r"); 4845 if (fp != NULL) { 4846 proc_stat_path = "/proc/self/task/%d/stat"; 4847 fclose(fp); 4848 } 4849 } 4850 4851 sprintf(proc_name, proc_stat_path, tid); 4852 fp = fopen(proc_name, "r"); 4853 if ( fp == NULL ) return -1; 4854 statlen = fread(stat, 1, 2047, fp); 4855 stat[statlen] = '\0'; 4856 fclose(fp); 4857 4858 // Skip pid and the command string. Note that we could be dealing with 4859 // weird command names, e.g. user could decide to rename java launcher 4860 // to "java 1.4.2 :)", then the stat file would look like 4861 // 1234 (java 1.4.2 :)) R ... ... 4862 // We don't really need to know the command string, just find the last 4863 // occurrence of ")" and then start parsing from there. See bug 4726580. 4864 s = strrchr(stat, ')'); 4865 i = 0; 4866 if (s == NULL ) return -1; 4867 4868 // Skip blank chars 4869 do s++; while (isspace(*s)); 4870 4871 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 4872 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 4873 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 4874 &user_time, &sys_time); 4875 if ( count != 13 ) return -1; 4876 if (user_sys_cpu_time) { 4877 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 4878 } else { 4879 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 4880 } 4881} 4882 4883void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4884 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4885 info_ptr->may_skip_backward = false; // elapsed time not wall time 4886 info_ptr->may_skip_forward = false; // elapsed time not wall time 4887 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4888} 4889 4890void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4891 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4892 info_ptr->may_skip_backward = false; // elapsed time not wall time 4893 info_ptr->may_skip_forward = false; // elapsed time not wall time 4894 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4895} 4896 4897bool os::is_thread_cpu_time_supported() { 4898 return true; 4899} 4900 4901// System loadavg support. Returns -1 if load average cannot be obtained. 4902// Linux doesn't yet have a (official) notion of processor sets, 4903// so just return the system wide load average. 4904int os::loadavg(double loadavg[], int nelem) { 4905 return ::getloadavg(loadavg, nelem); 4906} 4907 4908void os::pause() { 4909 char filename[MAX_PATH]; 4910 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 4911 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 4912 } else { 4913 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 4914 } 4915 4916 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 4917 if (fd != -1) { 4918 struct stat buf; 4919 ::close(fd); 4920 while (::stat(filename, &buf) == 0) { 4921 (void)::poll(NULL, 0, 100); 4922 } 4923 } else { 4924 jio_fprintf(stderr, 4925 "Could not open pause file '%s', continuing immediately.\n", filename); 4926 } 4927} 4928 4929 4930// Refer to the comments in os_solaris.cpp park-unpark. 4931// 4932// Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 4933// hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 4934// For specifics regarding the bug see GLIBC BUGID 261237 : 4935// http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 4936// Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 4937// will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 4938// is used. (The simple C test-case provided in the GLIBC bug report manifests the 4939// hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 4940// and monitorenter when we're using 1-0 locking. All those operations may result in 4941// calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 4942// of libpthread avoids the problem, but isn't practical. 4943// 4944// Possible remedies: 4945// 4946// 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 4947// This is palliative and probabilistic, however. If the thread is preempted 4948// between the call to compute_abstime() and pthread_cond_timedwait(), more 4949// than the minimum period may have passed, and the abstime may be stale (in the 4950// past) resultin in a hang. Using this technique reduces the odds of a hang 4951// but the JVM is still vulnerable, particularly on heavily loaded systems. 4952// 4953// 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 4954// of the usual flag-condvar-mutex idiom. The write side of the pipe is set 4955// NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 4956// reduces to poll()+read(). This works well, but consumes 2 FDs per extant 4957// thread. 4958// 4959// 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 4960// that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 4961// a timeout request to the chron thread and then blocking via pthread_cond_wait(). 4962// This also works well. In fact it avoids kernel-level scalability impediments 4963// on certain platforms that don't handle lots of active pthread_cond_timedwait() 4964// timers in a graceful fashion. 4965// 4966// 4. When the abstime value is in the past it appears that control returns 4967// correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 4968// Subsequent timedwait/wait calls may hang indefinitely. Given that, we 4969// can avoid the problem by reinitializing the condvar -- by cond_destroy() 4970// followed by cond_init() -- after all calls to pthread_cond_timedwait(). 4971// It may be possible to avoid reinitialization by checking the return 4972// value from pthread_cond_timedwait(). In addition to reinitializing the 4973// condvar we must establish the invariant that cond_signal() is only called 4974// within critical sections protected by the adjunct mutex. This prevents 4975// cond_signal() from "seeing" a condvar that's in the midst of being 4976// reinitialized or that is corrupt. Sadly, this invariant obviates the 4977// desirable signal-after-unlock optimization that avoids futile context switching. 4978// 4979// I'm also concerned that some versions of NTPL might allocate an auxilliary 4980// structure when a condvar is used or initialized. cond_destroy() would 4981// release the helper structure. Our reinitialize-after-timedwait fix 4982// put excessive stress on malloc/free and locks protecting the c-heap. 4983// 4984// We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 4985// It may be possible to refine (4) by checking the kernel and NTPL verisons 4986// and only enabling the work-around for vulnerable environments. 4987 4988// utility to compute the abstime argument to timedwait: 4989// millis is the relative timeout time 4990// abstime will be the absolute timeout time 4991// TODO: replace compute_abstime() with unpackTime() 4992 4993static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 4994 if (millis < 0) millis = 0; 4995 struct timeval now; 4996 int status = gettimeofday(&now, NULL); 4997 assert(status == 0, "gettimeofday"); 4998 jlong seconds = millis / 1000; 4999 millis %= 1000; 5000 if (seconds > 50000000) { // see man cond_timedwait(3T) 5001 seconds = 50000000; 5002 } 5003 abstime->tv_sec = now.tv_sec + seconds; 5004 long usec = now.tv_usec + millis * 1000; 5005 if (usec >= 1000000) { 5006 abstime->tv_sec += 1; 5007 usec -= 1000000; 5008 } 5009 abstime->tv_nsec = usec * 1000; 5010 return abstime; 5011} 5012 5013 5014// Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 5015// Conceptually TryPark() should be equivalent to park(0). 5016 5017int os::PlatformEvent::TryPark() { 5018 for (;;) { 5019 const int v = _Event ; 5020 guarantee ((v == 0) || (v == 1), "invariant") ; 5021 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 5022 } 5023} 5024 5025void os::PlatformEvent::park() { // AKA "down()" 5026 // Invariant: Only the thread associated with the Event/PlatformEvent 5027 // may call park(). 5028 // TODO: assert that _Assoc != NULL or _Assoc == Self 5029 int v ; 5030 for (;;) { 5031 v = _Event ; 5032 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5033 } 5034 guarantee (v >= 0, "invariant") ; 5035 if (v == 0) { 5036 // Do this the hard way by blocking ... 5037 int status = pthread_mutex_lock(_mutex); 5038 assert_status(status == 0, status, "mutex_lock"); 5039 guarantee (_nParked == 0, "invariant") ; 5040 ++ _nParked ; 5041 while (_Event < 0) { 5042 status = pthread_cond_wait(_cond, _mutex); 5043 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5044 // Treat this the same as if the wait was interrupted 5045 if (status == ETIME) { status = EINTR; } 5046 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5047 } 5048 -- _nParked ; 5049 5050 // In theory we could move the ST of 0 into _Event past the unlock(), 5051 // but then we'd need a MEMBAR after the ST. 5052 _Event = 0 ; 5053 status = pthread_mutex_unlock(_mutex); 5054 assert_status(status == 0, status, "mutex_unlock"); 5055 } 5056 guarantee (_Event >= 0, "invariant") ; 5057} 5058 5059int os::PlatformEvent::park(jlong millis) { 5060 guarantee (_nParked == 0, "invariant") ; 5061 5062 int v ; 5063 for (;;) { 5064 v = _Event ; 5065 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5066 } 5067 guarantee (v >= 0, "invariant") ; 5068 if (v != 0) return OS_OK ; 5069 5070 // We do this the hard way, by blocking the thread. 5071 // Consider enforcing a minimum timeout value. 5072 struct timespec abst; 5073 compute_abstime(&abst, millis); 5074 5075 int ret = OS_TIMEOUT; 5076 int status = pthread_mutex_lock(_mutex); 5077 assert_status(status == 0, status, "mutex_lock"); 5078 guarantee (_nParked == 0, "invariant") ; 5079 ++_nParked ; 5080 5081 // Object.wait(timo) will return because of 5082 // (a) notification 5083 // (b) timeout 5084 // (c) thread.interrupt 5085 // 5086 // Thread.interrupt and object.notify{All} both call Event::set. 5087 // That is, we treat thread.interrupt as a special case of notification. 5088 // The underlying Solaris implementation, cond_timedwait, admits 5089 // spurious/premature wakeups, but the JLS/JVM spec prevents the 5090 // JVM from making those visible to Java code. As such, we must 5091 // filter out spurious wakeups. We assume all ETIME returns are valid. 5092 // 5093 // TODO: properly differentiate simultaneous notify+interrupt. 5094 // In that case, we should propagate the notify to another waiter. 5095 5096 while (_Event < 0) { 5097 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5098 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5099 pthread_cond_destroy (_cond); 5100 pthread_cond_init (_cond, NULL) ; 5101 } 5102 assert_status(status == 0 || status == EINTR || 5103 status == ETIME || status == ETIMEDOUT, 5104 status, "cond_timedwait"); 5105 if (!FilterSpuriousWakeups) break ; // previous semantics 5106 if (status == ETIME || status == ETIMEDOUT) break ; 5107 // We consume and ignore EINTR and spurious wakeups. 5108 } 5109 --_nParked ; 5110 if (_Event >= 0) { 5111 ret = OS_OK; 5112 } 5113 _Event = 0 ; 5114 status = pthread_mutex_unlock(_mutex); 5115 assert_status(status == 0, status, "mutex_unlock"); 5116 assert (_nParked == 0, "invariant") ; 5117 return ret; 5118} 5119 5120void os::PlatformEvent::unpark() { 5121 int v, AnyWaiters ; 5122 for (;;) { 5123 v = _Event ; 5124 if (v > 0) { 5125 // The LD of _Event could have reordered or be satisfied 5126 // by a read-aside from this processor's write buffer. 5127 // To avoid problems execute a barrier and then 5128 // ratify the value. 5129 OrderAccess::fence() ; 5130 if (_Event == v) return ; 5131 continue ; 5132 } 5133 if (Atomic::cmpxchg (v+1, &_Event, v) == v) break ; 5134 } 5135 if (v < 0) { 5136 // Wait for the thread associated with the event to vacate 5137 int status = pthread_mutex_lock(_mutex); 5138 assert_status(status == 0, status, "mutex_lock"); 5139 AnyWaiters = _nParked ; 5140 assert (AnyWaiters == 0 || AnyWaiters == 1, "invariant") ; 5141 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5142 AnyWaiters = 0 ; 5143 pthread_cond_signal (_cond); 5144 } 5145 status = pthread_mutex_unlock(_mutex); 5146 assert_status(status == 0, status, "mutex_unlock"); 5147 if (AnyWaiters != 0) { 5148 status = pthread_cond_signal(_cond); 5149 assert_status(status == 0, status, "cond_signal"); 5150 } 5151 } 5152 5153 // Note that we signal() _after dropping the lock for "immortal" Events. 5154 // This is safe and avoids a common class of futile wakeups. In rare 5155 // circumstances this can cause a thread to return prematurely from 5156 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 5157 // simply re-test the condition and re-park itself. 5158} 5159 5160 5161// JSR166 5162// ------------------------------------------------------- 5163 5164/* 5165 * The solaris and linux implementations of park/unpark are fairly 5166 * conservative for now, but can be improved. They currently use a 5167 * mutex/condvar pair, plus a a count. 5168 * Park decrements count if > 0, else does a condvar wait. Unpark 5169 * sets count to 1 and signals condvar. Only one thread ever waits 5170 * on the condvar. Contention seen when trying to park implies that someone 5171 * is unparking you, so don't wait. And spurious returns are fine, so there 5172 * is no need to track notifications. 5173 */ 5174 5175#define MAX_SECS 100000000 5176/* 5177 * This code is common to linux and solaris and will be moved to a 5178 * common place in dolphin. 5179 * 5180 * The passed in time value is either a relative time in nanoseconds 5181 * or an absolute time in milliseconds. Either way it has to be unpacked 5182 * into suitable seconds and nanoseconds components and stored in the 5183 * given timespec structure. 5184 * Given time is a 64-bit value and the time_t used in the timespec is only 5185 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 5186 * overflow if times way in the future are given. Further on Solaris versions 5187 * prior to 10 there is a restriction (see cond_timedwait) that the specified 5188 * number of seconds, in abstime, is less than current_time + 100,000,000. 5189 * As it will be 28 years before "now + 100000000" will overflow we can 5190 * ignore overflow and just impose a hard-limit on seconds using the value 5191 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 5192 * years from "now". 5193 */ 5194 5195static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5196 assert (time > 0, "convertTime"); 5197 5198 struct timeval now; 5199 int status = gettimeofday(&now, NULL); 5200 assert(status == 0, "gettimeofday"); 5201 5202 time_t max_secs = now.tv_sec + MAX_SECS; 5203 5204 if (isAbsolute) { 5205 jlong secs = time / 1000; 5206 if (secs > max_secs) { 5207 absTime->tv_sec = max_secs; 5208 } 5209 else { 5210 absTime->tv_sec = secs; 5211 } 5212 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5213 } 5214 else { 5215 jlong secs = time / NANOSECS_PER_SEC; 5216 if (secs >= MAX_SECS) { 5217 absTime->tv_sec = max_secs; 5218 absTime->tv_nsec = 0; 5219 } 5220 else { 5221 absTime->tv_sec = now.tv_sec + secs; 5222 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5223 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5224 absTime->tv_nsec -= NANOSECS_PER_SEC; 5225 ++absTime->tv_sec; // note: this must be <= max_secs 5226 } 5227 } 5228 } 5229 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5230 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5231 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5232 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5233} 5234 5235void Parker::park(bool isAbsolute, jlong time) { 5236 // Optional fast-path check: 5237 // Return immediately if a permit is available. 5238 if (_counter > 0) { 5239 _counter = 0 ; 5240 OrderAccess::fence(); 5241 return ; 5242 } 5243 5244 Thread* thread = Thread::current(); 5245 assert(thread->is_Java_thread(), "Must be JavaThread"); 5246 JavaThread *jt = (JavaThread *)thread; 5247 5248 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5249 // Check interrupt before trying to wait 5250 if (Thread::is_interrupted(thread, false)) { 5251 return; 5252 } 5253 5254 // Next, demultiplex/decode time arguments 5255 timespec absTime; 5256 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all 5257 return; 5258 } 5259 if (time > 0) { 5260 unpackTime(&absTime, isAbsolute, time); 5261 } 5262 5263 5264 // Enter safepoint region 5265 // Beware of deadlocks such as 6317397. 5266 // The per-thread Parker:: mutex is a classic leaf-lock. 5267 // In particular a thread must never block on the Threads_lock while 5268 // holding the Parker:: mutex. If safepoints are pending both the 5269 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5270 ThreadBlockInVM tbivm(jt); 5271 5272 // Don't wait if cannot get lock since interference arises from 5273 // unblocking. Also. check interrupt before trying wait 5274 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5275 return; 5276 } 5277 5278 int status ; 5279 if (_counter > 0) { // no wait needed 5280 _counter = 0; 5281 status = pthread_mutex_unlock(_mutex); 5282 assert (status == 0, "invariant") ; 5283 OrderAccess::fence(); 5284 return; 5285 } 5286 5287#ifdef ASSERT 5288 // Don't catch signals while blocked; let the running threads have the signals. 5289 // (This allows a debugger to break into the running thread.) 5290 sigset_t oldsigs; 5291 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5292 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5293#endif 5294 5295 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5296 jt->set_suspend_equivalent(); 5297 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5298 5299 if (time == 0) { 5300 status = pthread_cond_wait (_cond, _mutex) ; 5301 } else { 5302 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ; 5303 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5304 pthread_cond_destroy (_cond) ; 5305 pthread_cond_init (_cond, NULL); 5306 } 5307 } 5308 assert_status(status == 0 || status == EINTR || 5309 status == ETIME || status == ETIMEDOUT, 5310 status, "cond_timedwait"); 5311 5312#ifdef ASSERT 5313 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5314#endif 5315 5316 _counter = 0 ; 5317 status = pthread_mutex_unlock(_mutex) ; 5318 assert_status(status == 0, status, "invariant") ; 5319 // If externally suspended while waiting, re-suspend 5320 if (jt->handle_special_suspend_equivalent_condition()) { 5321 jt->java_suspend_self(); 5322 } 5323 5324 OrderAccess::fence(); 5325} 5326 5327void Parker::unpark() { 5328 int s, status ; 5329 status = pthread_mutex_lock(_mutex); 5330 assert (status == 0, "invariant") ; 5331 s = _counter; 5332 _counter = 1; 5333 if (s < 1) { 5334 if (WorkAroundNPTLTimedWaitHang) { 5335 status = pthread_cond_signal (_cond) ; 5336 assert (status == 0, "invariant") ; 5337 status = pthread_mutex_unlock(_mutex); 5338 assert (status == 0, "invariant") ; 5339 } else { 5340 status = pthread_mutex_unlock(_mutex); 5341 assert (status == 0, "invariant") ; 5342 status = pthread_cond_signal (_cond) ; 5343 assert (status == 0, "invariant") ; 5344 } 5345 } else { 5346 pthread_mutex_unlock(_mutex); 5347 assert (status == 0, "invariant") ; 5348 } 5349} 5350 5351 5352extern char** environ; 5353 5354#ifndef __NR_fork 5355#define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5356#endif 5357 5358#ifndef __NR_execve 5359#define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 5360#endif 5361 5362// Run the specified command in a separate process. Return its exit value, 5363// or -1 on failure (e.g. can't fork a new process). 5364// Unlike system(), this function can be called from signal handler. It 5365// doesn't block SIGINT et al. 5366int os::fork_and_exec(char* cmd) { 5367 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5368 5369 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5370 // pthread_atfork handlers and reset pthread library. All we need is a 5371 // separate process to execve. Make a direct syscall to fork process. 5372 // On IA64 there's no fork syscall, we have to use fork() and hope for 5373 // the best... 5374 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5375 IA64_ONLY(fork();) 5376 5377 if (pid < 0) { 5378 // fork failed 5379 return -1; 5380 5381 } else if (pid == 0) { 5382 // child process 5383 5384 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5385 // first to kill every thread on the thread list. Because this list is 5386 // not reset by fork() (see notes above), execve() will instead kill 5387 // every thread in the parent process. We know this is the only thread 5388 // in the new process, so make a system call directly. 5389 // IA64 should use normal execve() from glibc to match the glibc fork() 5390 // above. 5391 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5392 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5393 5394 // execve failed 5395 _exit(-1); 5396 5397 } else { 5398 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5399 // care about the actual exit code, for now. 5400 5401 int status; 5402 5403 // Wait for the child process to exit. This returns immediately if 5404 // the child has already exited. */ 5405 while (waitpid(pid, &status, 0) < 0) { 5406 switch (errno) { 5407 case ECHILD: return 0; 5408 case EINTR: break; 5409 default: return -1; 5410 } 5411 } 5412 5413 if (WIFEXITED(status)) { 5414 // The child exited normally; get its exit code. 5415 return WEXITSTATUS(status); 5416 } else if (WIFSIGNALED(status)) { 5417 // The child exited because of a signal 5418 // The best value to return is 0x80 + signal number, 5419 // because that is what all Unix shells do, and because 5420 // it allows callers to distinguish between process exit and 5421 // process death by signal. 5422 return 0x80 + WTERMSIG(status); 5423 } else { 5424 // Unknown exit code; pass it through 5425 return status; 5426 } 5427 } 5428} 5429 5430// is_headless_jre() 5431// 5432// Test for the existence of xawt/libmawt.so or libawt_xawt.so 5433// in order to report if we are running in a headless jre 5434// 5435// Since JDK8 xawt/libmawt.so was moved into the same directory 5436// as libawt.so, and renamed libawt_xawt.so 5437// 5438bool os::is_headless_jre() { 5439 struct stat statbuf; 5440 char buf[MAXPATHLEN]; 5441 char libmawtpath[MAXPATHLEN]; 5442 const char *xawtstr = "/xawt/libmawt.so"; 5443 const char *new_xawtstr = "/libawt_xawt.so"; 5444 char *p; 5445 5446 // Get path to libjvm.so 5447 os::jvm_path(buf, sizeof(buf)); 5448 5449 // Get rid of libjvm.so 5450 p = strrchr(buf, '/'); 5451 if (p == NULL) return false; 5452 else *p = '\0'; 5453 5454 // Get rid of client or server 5455 p = strrchr(buf, '/'); 5456 if (p == NULL) return false; 5457 else *p = '\0'; 5458 5459 // check xawt/libmawt.so 5460 strcpy(libmawtpath, buf); 5461 strcat(libmawtpath, xawtstr); 5462 if (::stat(libmawtpath, &statbuf) == 0) return false; 5463 5464 // check libawt_xawt.so 5465 strcpy(libmawtpath, buf); 5466 strcat(libmawtpath, new_xawtstr); 5467 if (::stat(libmawtpath, &statbuf) == 0) return false; 5468 5469 return true; 5470} 5471 5472 5473#ifdef JAVASE_EMBEDDED 5474// 5475// A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory. 5476// 5477MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL; 5478 5479// ctor 5480// 5481MemNotifyThread::MemNotifyThread(int fd): Thread() { 5482 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread"); 5483 _fd = fd; 5484 5485 if (os::create_thread(this, os::os_thread)) { 5486 _memnotify_thread = this; 5487 os::set_priority(this, NearMaxPriority); 5488 os::start_thread(this); 5489 } 5490} 5491 5492// Where all the work gets done 5493// 5494void MemNotifyThread::run() { 5495 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread"); 5496 5497 // Set up the select arguments 5498 fd_set rfds; 5499 if (_fd != -1) { 5500 FD_ZERO(&rfds); 5501 FD_SET(_fd, &rfds); 5502 } 5503 5504 // Now wait for the mem_notify device to wake up 5505 while (1) { 5506 // Wait for the mem_notify device to signal us.. 5507 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL); 5508 if (rc == -1) { 5509 perror("select!\n"); 5510 break; 5511 } else if (rc) { 5512 //ssize_t free_before = os::available_memory(); 5513 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024); 5514 5515 // The kernel is telling us there is not much memory left... 5516 // try to do something about that 5517 5518 // If we are not already in a GC, try one. 5519 if (!Universe::heap()->is_gc_active()) { 5520 Universe::heap()->collect(GCCause::_allocation_failure); 5521 5522 //ssize_t free_after = os::available_memory(); 5523 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024); 5524 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024); 5525 } 5526 // We might want to do something like the following if we find the GC's are not helping... 5527 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true); 5528 } 5529 } 5530} 5531 5532// 5533// See if the /dev/mem_notify device exists, and if so, start a thread to monitor it. 5534// 5535void MemNotifyThread::start() { 5536 int fd; 5537 fd = open ("/dev/mem_notify", O_RDONLY, 0); 5538 if (fd < 0) { 5539 return; 5540 } 5541 5542 if (memnotify_thread() == NULL) { 5543 new MemNotifyThread(fd); 5544 } 5545} 5546#endif // JAVASE_EMBEDDED 5547