os_linux.cpp revision 4423:15c04fe93c18
1/* 2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25// no precompiled headers 26#include "classfile/classLoader.hpp" 27#include "classfile/systemDictionary.hpp" 28#include "classfile/vmSymbols.hpp" 29#include "code/icBuffer.hpp" 30#include "code/vtableStubs.hpp" 31#include "compiler/compileBroker.hpp" 32#include "compiler/disassembler.hpp" 33#include "interpreter/interpreter.hpp" 34#include "jvm_linux.h" 35#include "memory/allocation.inline.hpp" 36#include "memory/filemap.hpp" 37#include "mutex_linux.inline.hpp" 38#include "oops/oop.inline.hpp" 39#include "os_share_linux.hpp" 40#include "prims/jniFastGetField.hpp" 41#include "prims/jvm.h" 42#include "prims/jvm_misc.hpp" 43#include "runtime/arguments.hpp" 44#include "runtime/extendedPC.hpp" 45#include "runtime/globals.hpp" 46#include "runtime/interfaceSupport.hpp" 47#include "runtime/init.hpp" 48#include "runtime/java.hpp" 49#include "runtime/javaCalls.hpp" 50#include "runtime/mutexLocker.hpp" 51#include "runtime/objectMonitor.hpp" 52#include "runtime/osThread.hpp" 53#include "runtime/perfMemory.hpp" 54#include "runtime/sharedRuntime.hpp" 55#include "runtime/statSampler.hpp" 56#include "runtime/stubRoutines.hpp" 57#include "runtime/thread.inline.hpp" 58#include "runtime/threadCritical.hpp" 59#include "runtime/timer.hpp" 60#include "services/attachListener.hpp" 61#include "services/memTracker.hpp" 62#include "services/runtimeService.hpp" 63#include "utilities/decoder.hpp" 64#include "utilities/defaultStream.hpp" 65#include "utilities/events.hpp" 66#include "utilities/elfFile.hpp" 67#include "utilities/growableArray.hpp" 68#include "utilities/vmError.hpp" 69 70// put OS-includes here 71# include <sys/types.h> 72# include <sys/mman.h> 73# include <sys/stat.h> 74# include <sys/select.h> 75# include <pthread.h> 76# include <signal.h> 77# include <errno.h> 78# include <dlfcn.h> 79# include <stdio.h> 80# include <unistd.h> 81# include <sys/resource.h> 82# include <pthread.h> 83# include <sys/stat.h> 84# include <sys/time.h> 85# include <sys/times.h> 86# include <sys/utsname.h> 87# include <sys/socket.h> 88# include <sys/wait.h> 89# include <pwd.h> 90# include <poll.h> 91# include <semaphore.h> 92# include <fcntl.h> 93# include <string.h> 94# include <syscall.h> 95# include <sys/sysinfo.h> 96# include <gnu/libc-version.h> 97# include <sys/ipc.h> 98# include <sys/shm.h> 99# include <link.h> 100# include <stdint.h> 101# include <inttypes.h> 102# include <sys/ioctl.h> 103 104#define MAX_PATH (2 * K) 105 106// for timer info max values which include all bits 107#define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 108 109#define LARGEPAGES_BIT (1 << 6) 110//////////////////////////////////////////////////////////////////////////////// 111// global variables 112julong os::Linux::_physical_memory = 0; 113 114address os::Linux::_initial_thread_stack_bottom = NULL; 115uintptr_t os::Linux::_initial_thread_stack_size = 0; 116 117int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 118int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 119Mutex* os::Linux::_createThread_lock = NULL; 120pthread_t os::Linux::_main_thread; 121int os::Linux::_page_size = -1; 122bool os::Linux::_is_floating_stack = false; 123bool os::Linux::_is_NPTL = false; 124bool os::Linux::_supports_fast_thread_cpu_time = false; 125const char * os::Linux::_glibc_version = NULL; 126const char * os::Linux::_libpthread_version = NULL; 127 128static jlong initial_time_count=0; 129 130static int clock_tics_per_sec = 100; 131 132// For diagnostics to print a message once. see run_periodic_checks 133static sigset_t check_signal_done; 134static bool check_signals = true;; 135 136static pid_t _initial_pid = 0; 137 138/* Signal number used to suspend/resume a thread */ 139 140/* do not use any signal number less than SIGSEGV, see 4355769 */ 141static int SR_signum = SIGUSR2; 142sigset_t SR_sigset; 143 144/* Used to protect dlsym() calls */ 145static pthread_mutex_t dl_mutex; 146 147#ifdef JAVASE_EMBEDDED 148class MemNotifyThread: public Thread { 149 friend class VMStructs; 150 public: 151 virtual void run(); 152 153 private: 154 static MemNotifyThread* _memnotify_thread; 155 int _fd; 156 157 public: 158 159 // Constructor 160 MemNotifyThread(int fd); 161 162 // Tester 163 bool is_memnotify_thread() const { return true; } 164 165 // Printing 166 char* name() const { return (char*)"Linux MemNotify Thread"; } 167 168 // Returns the single instance of the MemNotifyThread 169 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; } 170 171 // Create and start the single instance of MemNotifyThread 172 static void start(); 173}; 174#endif // JAVASE_EMBEDDED 175 176// utility functions 177 178static int SR_initialize(); 179static int SR_finalize(); 180 181julong os::available_memory() { 182 return Linux::available_memory(); 183} 184 185julong os::Linux::available_memory() { 186 // values in struct sysinfo are "unsigned long" 187 struct sysinfo si; 188 sysinfo(&si); 189 190 return (julong)si.freeram * si.mem_unit; 191} 192 193julong os::physical_memory() { 194 return Linux::physical_memory(); 195} 196 197//////////////////////////////////////////////////////////////////////////////// 198// environment support 199 200bool os::getenv(const char* name, char* buf, int len) { 201 const char* val = ::getenv(name); 202 if (val != NULL && strlen(val) < (size_t)len) { 203 strcpy(buf, val); 204 return true; 205 } 206 if (len > 0) buf[0] = 0; // return a null string 207 return false; 208} 209 210 211// Return true if user is running as root. 212 213bool os::have_special_privileges() { 214 static bool init = false; 215 static bool privileges = false; 216 if (!init) { 217 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 218 init = true; 219 } 220 return privileges; 221} 222 223 224#ifndef SYS_gettid 225// i386: 224, ia64: 1105, amd64: 186, sparc 143 226#ifdef __ia64__ 227#define SYS_gettid 1105 228#elif __i386__ 229#define SYS_gettid 224 230#elif __amd64__ 231#define SYS_gettid 186 232#elif __sparc__ 233#define SYS_gettid 143 234#else 235#error define gettid for the arch 236#endif 237#endif 238 239// Cpu architecture string 240#if defined(ZERO) 241static char cpu_arch[] = ZERO_LIBARCH; 242#elif defined(IA64) 243static char cpu_arch[] = "ia64"; 244#elif defined(IA32) 245static char cpu_arch[] = "i386"; 246#elif defined(AMD64) 247static char cpu_arch[] = "amd64"; 248#elif defined(ARM) 249static char cpu_arch[] = "arm"; 250#elif defined(PPC) 251static char cpu_arch[] = "ppc"; 252#elif defined(SPARC) 253# ifdef _LP64 254static char cpu_arch[] = "sparcv9"; 255# else 256static char cpu_arch[] = "sparc"; 257# endif 258#else 259#error Add appropriate cpu_arch setting 260#endif 261 262 263// pid_t gettid() 264// 265// Returns the kernel thread id of the currently running thread. Kernel 266// thread id is used to access /proc. 267// 268// (Note that getpid() on LinuxThreads returns kernel thread id too; but 269// on NPTL, it returns the same pid for all threads, as required by POSIX.) 270// 271pid_t os::Linux::gettid() { 272 int rslt = syscall(SYS_gettid); 273 if (rslt == -1) { 274 // old kernel, no NPTL support 275 return getpid(); 276 } else { 277 return (pid_t)rslt; 278 } 279} 280 281// Most versions of linux have a bug where the number of processors are 282// determined by looking at the /proc file system. In a chroot environment, 283// the system call returns 1. This causes the VM to act as if it is 284// a single processor and elide locking (see is_MP() call). 285static bool unsafe_chroot_detected = false; 286static const char *unstable_chroot_error = "/proc file system not found.\n" 287 "Java may be unstable running multithreaded in a chroot " 288 "environment on Linux when /proc filesystem is not mounted."; 289 290void os::Linux::initialize_system_info() { 291 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 292 if (processor_count() == 1) { 293 pid_t pid = os::Linux::gettid(); 294 char fname[32]; 295 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 296 FILE *fp = fopen(fname, "r"); 297 if (fp == NULL) { 298 unsafe_chroot_detected = true; 299 } else { 300 fclose(fp); 301 } 302 } 303 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 304 assert(processor_count() > 0, "linux error"); 305} 306 307void os::init_system_properties_values() { 308// char arch[12]; 309// sysinfo(SI_ARCHITECTURE, arch, sizeof(arch)); 310 311 // The next steps are taken in the product version: 312 // 313 // Obtain the JAVA_HOME value from the location of libjvm.so. 314 // This library should be located at: 315 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 316 // 317 // If "/jre/lib/" appears at the right place in the path, then we 318 // assume libjvm.so is installed in a JDK and we use this path. 319 // 320 // Otherwise exit with message: "Could not create the Java virtual machine." 321 // 322 // The following extra steps are taken in the debugging version: 323 // 324 // If "/jre/lib/" does NOT appear at the right place in the path 325 // instead of exit check for $JAVA_HOME environment variable. 326 // 327 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 328 // then we append a fake suffix "hotspot/libjvm.so" to this path so 329 // it looks like libjvm.so is installed there 330 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 331 // 332 // Otherwise exit. 333 // 334 // Important note: if the location of libjvm.so changes this 335 // code needs to be changed accordingly. 336 337 // The next few definitions allow the code to be verbatim: 338#define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n), mtInternal) 339#define getenv(n) ::getenv(n) 340 341/* 342 * See ld(1): 343 * The linker uses the following search paths to locate required 344 * shared libraries: 345 * 1: ... 346 * ... 347 * 7: The default directories, normally /lib and /usr/lib. 348 */ 349#if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 350#define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 351#else 352#define DEFAULT_LIBPATH "/lib:/usr/lib" 353#endif 354 355#define EXTENSIONS_DIR "/lib/ext" 356#define ENDORSED_DIR "/lib/endorsed" 357#define REG_DIR "/usr/java/packages" 358 359 { 360 /* sysclasspath, java_home, dll_dir */ 361 { 362 char *home_path; 363 char *dll_path; 364 char *pslash; 365 char buf[MAXPATHLEN]; 366 os::jvm_path(buf, sizeof(buf)); 367 368 // Found the full path to libjvm.so. 369 // Now cut the path to <java_home>/jre if we can. 370 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */ 371 pslash = strrchr(buf, '/'); 372 if (pslash != NULL) 373 *pslash = '\0'; /* get rid of /{client|server|hotspot} */ 374 dll_path = malloc(strlen(buf) + 1); 375 if (dll_path == NULL) 376 return; 377 strcpy(dll_path, buf); 378 Arguments::set_dll_dir(dll_path); 379 380 if (pslash != NULL) { 381 pslash = strrchr(buf, '/'); 382 if (pslash != NULL) { 383 *pslash = '\0'; /* get rid of /<arch> */ 384 pslash = strrchr(buf, '/'); 385 if (pslash != NULL) 386 *pslash = '\0'; /* get rid of /lib */ 387 } 388 } 389 390 home_path = malloc(strlen(buf) + 1); 391 if (home_path == NULL) 392 return; 393 strcpy(home_path, buf); 394 Arguments::set_java_home(home_path); 395 396 if (!set_boot_path('/', ':')) 397 return; 398 } 399 400 /* 401 * Where to look for native libraries 402 * 403 * Note: Due to a legacy implementation, most of the library path 404 * is set in the launcher. This was to accomodate linking restrictions 405 * on legacy Linux implementations (which are no longer supported). 406 * Eventually, all the library path setting will be done here. 407 * 408 * However, to prevent the proliferation of improperly built native 409 * libraries, the new path component /usr/java/packages is added here. 410 * Eventually, all the library path setting will be done here. 411 */ 412 { 413 char *ld_library_path; 414 415 /* 416 * Construct the invariant part of ld_library_path. Note that the 417 * space for the colon and the trailing null are provided by the 418 * nulls included by the sizeof operator (so actually we allocate 419 * a byte more than necessary). 420 */ 421 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") + 422 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH)); 423 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch); 424 425 /* 426 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It 427 * should always exist (until the legacy problem cited above is 428 * addressed). 429 */ 430 char *v = getenv("LD_LIBRARY_PATH"); 431 if (v != NULL) { 432 char *t = ld_library_path; 433 /* That's +1 for the colon and +1 for the trailing '\0' */ 434 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1); 435 sprintf(ld_library_path, "%s:%s", v, t); 436 } 437 Arguments::set_library_path(ld_library_path); 438 } 439 440 /* 441 * Extensions directories. 442 * 443 * Note that the space for the colon and the trailing null are provided 444 * by the nulls included by the sizeof operator (so actually one byte more 445 * than necessary is allocated). 446 */ 447 { 448 char *buf = malloc(strlen(Arguments::get_java_home()) + 449 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR)); 450 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR, 451 Arguments::get_java_home()); 452 Arguments::set_ext_dirs(buf); 453 } 454 455 /* Endorsed standards default directory. */ 456 { 457 char * buf; 458 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR)); 459 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 460 Arguments::set_endorsed_dirs(buf); 461 } 462 } 463 464#undef malloc 465#undef getenv 466#undef EXTENSIONS_DIR 467#undef ENDORSED_DIR 468 469 // Done 470 return; 471} 472 473//////////////////////////////////////////////////////////////////////////////// 474// breakpoint support 475 476void os::breakpoint() { 477 BREAKPOINT; 478} 479 480extern "C" void breakpoint() { 481 // use debugger to set breakpoint here 482} 483 484//////////////////////////////////////////////////////////////////////////////// 485// signal support 486 487debug_only(static bool signal_sets_initialized = false); 488static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 489 490bool os::Linux::is_sig_ignored(int sig) { 491 struct sigaction oact; 492 sigaction(sig, (struct sigaction*)NULL, &oact); 493 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 494 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 495 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 496 return true; 497 else 498 return false; 499} 500 501void os::Linux::signal_sets_init() { 502 // Should also have an assertion stating we are still single-threaded. 503 assert(!signal_sets_initialized, "Already initialized"); 504 // Fill in signals that are necessarily unblocked for all threads in 505 // the VM. Currently, we unblock the following signals: 506 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 507 // by -Xrs (=ReduceSignalUsage)); 508 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 509 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 510 // the dispositions or masks wrt these signals. 511 // Programs embedding the VM that want to use the above signals for their 512 // own purposes must, at this time, use the "-Xrs" option to prevent 513 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 514 // (See bug 4345157, and other related bugs). 515 // In reality, though, unblocking these signals is really a nop, since 516 // these signals are not blocked by default. 517 sigemptyset(&unblocked_sigs); 518 sigemptyset(&allowdebug_blocked_sigs); 519 sigaddset(&unblocked_sigs, SIGILL); 520 sigaddset(&unblocked_sigs, SIGSEGV); 521 sigaddset(&unblocked_sigs, SIGBUS); 522 sigaddset(&unblocked_sigs, SIGFPE); 523 sigaddset(&unblocked_sigs, SR_signum); 524 525 if (!ReduceSignalUsage) { 526 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 527 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 528 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 529 } 530 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 531 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 532 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 533 } 534 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 535 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 536 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 537 } 538 } 539 // Fill in signals that are blocked by all but the VM thread. 540 sigemptyset(&vm_sigs); 541 if (!ReduceSignalUsage) 542 sigaddset(&vm_sigs, BREAK_SIGNAL); 543 debug_only(signal_sets_initialized = true); 544 545} 546 547// These are signals that are unblocked while a thread is running Java. 548// (For some reason, they get blocked by default.) 549sigset_t* os::Linux::unblocked_signals() { 550 assert(signal_sets_initialized, "Not initialized"); 551 return &unblocked_sigs; 552} 553 554// These are the signals that are blocked while a (non-VM) thread is 555// running Java. Only the VM thread handles these signals. 556sigset_t* os::Linux::vm_signals() { 557 assert(signal_sets_initialized, "Not initialized"); 558 return &vm_sigs; 559} 560 561// These are signals that are blocked during cond_wait to allow debugger in 562sigset_t* os::Linux::allowdebug_blocked_signals() { 563 assert(signal_sets_initialized, "Not initialized"); 564 return &allowdebug_blocked_sigs; 565} 566 567void os::Linux::hotspot_sigmask(Thread* thread) { 568 569 //Save caller's signal mask before setting VM signal mask 570 sigset_t caller_sigmask; 571 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 572 573 OSThread* osthread = thread->osthread(); 574 osthread->set_caller_sigmask(caller_sigmask); 575 576 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 577 578 if (!ReduceSignalUsage) { 579 if (thread->is_VM_thread()) { 580 // Only the VM thread handles BREAK_SIGNAL ... 581 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 582 } else { 583 // ... all other threads block BREAK_SIGNAL 584 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 585 } 586 } 587} 588 589////////////////////////////////////////////////////////////////////////////// 590// detecting pthread library 591 592void os::Linux::libpthread_init() { 593 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 594 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 595 // generic name for earlier versions. 596 // Define macros here so we can build HotSpot on old systems. 597# ifndef _CS_GNU_LIBC_VERSION 598# define _CS_GNU_LIBC_VERSION 2 599# endif 600# ifndef _CS_GNU_LIBPTHREAD_VERSION 601# define _CS_GNU_LIBPTHREAD_VERSION 3 602# endif 603 604 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 605 if (n > 0) { 606 char *str = (char *)malloc(n, mtInternal); 607 confstr(_CS_GNU_LIBC_VERSION, str, n); 608 os::Linux::set_glibc_version(str); 609 } else { 610 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 611 static char _gnu_libc_version[32]; 612 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 613 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 614 os::Linux::set_glibc_version(_gnu_libc_version); 615 } 616 617 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 618 if (n > 0) { 619 char *str = (char *)malloc(n, mtInternal); 620 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 621 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 622 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 623 // is the case. LinuxThreads has a hard limit on max number of threads. 624 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 625 // On the other hand, NPTL does not have such a limit, sysconf() 626 // will return -1 and errno is not changed. Check if it is really NPTL. 627 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 628 strstr(str, "NPTL") && 629 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 630 free(str); 631 os::Linux::set_libpthread_version("linuxthreads"); 632 } else { 633 os::Linux::set_libpthread_version(str); 634 } 635 } else { 636 // glibc before 2.3.2 only has LinuxThreads. 637 os::Linux::set_libpthread_version("linuxthreads"); 638 } 639 640 if (strstr(libpthread_version(), "NPTL")) { 641 os::Linux::set_is_NPTL(); 642 } else { 643 os::Linux::set_is_LinuxThreads(); 644 } 645 646 // LinuxThreads have two flavors: floating-stack mode, which allows variable 647 // stack size; and fixed-stack mode. NPTL is always floating-stack. 648 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 649 os::Linux::set_is_floating_stack(); 650 } 651} 652 653///////////////////////////////////////////////////////////////////////////// 654// thread stack 655 656// Force Linux kernel to expand current thread stack. If "bottom" is close 657// to the stack guard, caller should block all signals. 658// 659// MAP_GROWSDOWN: 660// A special mmap() flag that is used to implement thread stacks. It tells 661// kernel that the memory region should extend downwards when needed. This 662// allows early versions of LinuxThreads to only mmap the first few pages 663// when creating a new thread. Linux kernel will automatically expand thread 664// stack as needed (on page faults). 665// 666// However, because the memory region of a MAP_GROWSDOWN stack can grow on 667// demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 668// region, it's hard to tell if the fault is due to a legitimate stack 669// access or because of reading/writing non-exist memory (e.g. buffer 670// overrun). As a rule, if the fault happens below current stack pointer, 671// Linux kernel does not expand stack, instead a SIGSEGV is sent to the 672// application (see Linux kernel fault.c). 673// 674// This Linux feature can cause SIGSEGV when VM bangs thread stack for 675// stack overflow detection. 676// 677// Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 678// not use this flag. However, the stack of initial thread is not created 679// by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 680// unlikely) that user code can create a thread with MAP_GROWSDOWN stack 681// and then attach the thread to JVM. 682// 683// To get around the problem and allow stack banging on Linux, we need to 684// manually expand thread stack after receiving the SIGSEGV. 685// 686// There are two ways to expand thread stack to address "bottom", we used 687// both of them in JVM before 1.5: 688// 1. adjust stack pointer first so that it is below "bottom", and then 689// touch "bottom" 690// 2. mmap() the page in question 691// 692// Now alternate signal stack is gone, it's harder to use 2. For instance, 693// if current sp is already near the lower end of page 101, and we need to 694// call mmap() to map page 100, it is possible that part of the mmap() frame 695// will be placed in page 100. When page 100 is mapped, it is zero-filled. 696// That will destroy the mmap() frame and cause VM to crash. 697// 698// The following code works by adjusting sp first, then accessing the "bottom" 699// page to force a page fault. Linux kernel will then automatically expand the 700// stack mapping. 701// 702// _expand_stack_to() assumes its frame size is less than page size, which 703// should always be true if the function is not inlined. 704 705#if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 706#define NOINLINE 707#else 708#define NOINLINE __attribute__ ((noinline)) 709#endif 710 711static void _expand_stack_to(address bottom) NOINLINE; 712 713static void _expand_stack_to(address bottom) { 714 address sp; 715 size_t size; 716 volatile char *p; 717 718 // Adjust bottom to point to the largest address within the same page, it 719 // gives us a one-page buffer if alloca() allocates slightly more memory. 720 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 721 bottom += os::Linux::page_size() - 1; 722 723 // sp might be slightly above current stack pointer; if that's the case, we 724 // will alloca() a little more space than necessary, which is OK. Don't use 725 // os::current_stack_pointer(), as its result can be slightly below current 726 // stack pointer, causing us to not alloca enough to reach "bottom". 727 sp = (address)&sp; 728 729 if (sp > bottom) { 730 size = sp - bottom; 731 p = (volatile char *)alloca(size); 732 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 733 p[0] = '\0'; 734 } 735} 736 737bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 738 assert(t!=NULL, "just checking"); 739 assert(t->osthread()->expanding_stack(), "expand should be set"); 740 assert(t->stack_base() != NULL, "stack_base was not initialized"); 741 742 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 743 sigset_t mask_all, old_sigset; 744 sigfillset(&mask_all); 745 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 746 _expand_stack_to(addr); 747 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 748 return true; 749 } 750 return false; 751} 752 753////////////////////////////////////////////////////////////////////////////// 754// create new thread 755 756static address highest_vm_reserved_address(); 757 758// check if it's safe to start a new thread 759static bool _thread_safety_check(Thread* thread) { 760 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 761 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 762 // Heap is mmap'ed at lower end of memory space. Thread stacks are 763 // allocated (MAP_FIXED) from high address space. Every thread stack 764 // occupies a fixed size slot (usually 2Mbytes, but user can change 765 // it to other values if they rebuild LinuxThreads). 766 // 767 // Problem with MAP_FIXED is that mmap() can still succeed even part of 768 // the memory region has already been mmap'ed. That means if we have too 769 // many threads and/or very large heap, eventually thread stack will 770 // collide with heap. 771 // 772 // Here we try to prevent heap/stack collision by comparing current 773 // stack bottom with the highest address that has been mmap'ed by JVM 774 // plus a safety margin for memory maps created by native code. 775 // 776 // This feature can be disabled by setting ThreadSafetyMargin to 0 777 // 778 if (ThreadSafetyMargin > 0) { 779 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 780 781 // not safe if our stack extends below the safety margin 782 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 783 } else { 784 return true; 785 } 786 } else { 787 // Floating stack LinuxThreads or NPTL: 788 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 789 // there's not enough space left, pthread_create() will fail. If we come 790 // here, that means enough space has been reserved for stack. 791 return true; 792 } 793} 794 795// Thread start routine for all newly created threads 796static void *java_start(Thread *thread) { 797 // Try to randomize the cache line index of hot stack frames. 798 // This helps when threads of the same stack traces evict each other's 799 // cache lines. The threads can be either from the same JVM instance, or 800 // from different JVM instances. The benefit is especially true for 801 // processors with hyperthreading technology. 802 static int counter = 0; 803 int pid = os::current_process_id(); 804 alloca(((pid ^ counter++) & 7) * 128); 805 806 ThreadLocalStorage::set_thread(thread); 807 808 OSThread* osthread = thread->osthread(); 809 Monitor* sync = osthread->startThread_lock(); 810 811 // non floating stack LinuxThreads needs extra check, see above 812 if (!_thread_safety_check(thread)) { 813 // notify parent thread 814 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 815 osthread->set_state(ZOMBIE); 816 sync->notify_all(); 817 return NULL; 818 } 819 820 // thread_id is kernel thread id (similar to Solaris LWP id) 821 osthread->set_thread_id(os::Linux::gettid()); 822 823 if (UseNUMA) { 824 int lgrp_id = os::numa_get_group_id(); 825 if (lgrp_id != -1) { 826 thread->set_lgrp_id(lgrp_id); 827 } 828 } 829 // initialize signal mask for this thread 830 os::Linux::hotspot_sigmask(thread); 831 832 // initialize floating point control register 833 os::Linux::init_thread_fpu_state(); 834 835 // handshaking with parent thread 836 { 837 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 838 839 // notify parent thread 840 osthread->set_state(INITIALIZED); 841 sync->notify_all(); 842 843 // wait until os::start_thread() 844 while (osthread->get_state() == INITIALIZED) { 845 sync->wait(Mutex::_no_safepoint_check_flag); 846 } 847 } 848 849 // call one more level start routine 850 thread->run(); 851 852 return 0; 853} 854 855bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 856 assert(thread->osthread() == NULL, "caller responsible"); 857 858 // Allocate the OSThread object 859 OSThread* osthread = new OSThread(NULL, NULL); 860 if (osthread == NULL) { 861 return false; 862 } 863 864 // set the correct thread state 865 osthread->set_thread_type(thr_type); 866 867 // Initial state is ALLOCATED but not INITIALIZED 868 osthread->set_state(ALLOCATED); 869 870 thread->set_osthread(osthread); 871 872 // init thread attributes 873 pthread_attr_t attr; 874 pthread_attr_init(&attr); 875 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 876 877 // stack size 878 if (os::Linux::supports_variable_stack_size()) { 879 // calculate stack size if it's not specified by caller 880 if (stack_size == 0) { 881 stack_size = os::Linux::default_stack_size(thr_type); 882 883 switch (thr_type) { 884 case os::java_thread: 885 // Java threads use ThreadStackSize which default value can be 886 // changed with the flag -Xss 887 assert (JavaThread::stack_size_at_create() > 0, "this should be set"); 888 stack_size = JavaThread::stack_size_at_create(); 889 break; 890 case os::compiler_thread: 891 if (CompilerThreadStackSize > 0) { 892 stack_size = (size_t)(CompilerThreadStackSize * K); 893 break; 894 } // else fall through: 895 // use VMThreadStackSize if CompilerThreadStackSize is not defined 896 case os::vm_thread: 897 case os::pgc_thread: 898 case os::cgc_thread: 899 case os::watcher_thread: 900 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 901 break; 902 } 903 } 904 905 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 906 pthread_attr_setstacksize(&attr, stack_size); 907 } else { 908 // let pthread_create() pick the default value. 909 } 910 911 // glibc guard page 912 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 913 914 ThreadState state; 915 916 { 917 // Serialize thread creation if we are running with fixed stack LinuxThreads 918 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 919 if (lock) { 920 os::Linux::createThread_lock()->lock_without_safepoint_check(); 921 } 922 923 pthread_t tid; 924 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 925 926 pthread_attr_destroy(&attr); 927 928 if (ret != 0) { 929 if (PrintMiscellaneous && (Verbose || WizardMode)) { 930 perror("pthread_create()"); 931 } 932 // Need to clean up stuff we've allocated so far 933 thread->set_osthread(NULL); 934 delete osthread; 935 if (lock) os::Linux::createThread_lock()->unlock(); 936 return false; 937 } 938 939 // Store pthread info into the OSThread 940 osthread->set_pthread_id(tid); 941 942 // Wait until child thread is either initialized or aborted 943 { 944 Monitor* sync_with_child = osthread->startThread_lock(); 945 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 946 while ((state = osthread->get_state()) == ALLOCATED) { 947 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 948 } 949 } 950 951 if (lock) { 952 os::Linux::createThread_lock()->unlock(); 953 } 954 } 955 956 // Aborted due to thread limit being reached 957 if (state == ZOMBIE) { 958 thread->set_osthread(NULL); 959 delete osthread; 960 return false; 961 } 962 963 // The thread is returned suspended (in state INITIALIZED), 964 // and is started higher up in the call chain 965 assert(state == INITIALIZED, "race condition"); 966 return true; 967} 968 969///////////////////////////////////////////////////////////////////////////// 970// attach existing thread 971 972// bootstrap the main thread 973bool os::create_main_thread(JavaThread* thread) { 974 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 975 return create_attached_thread(thread); 976} 977 978bool os::create_attached_thread(JavaThread* thread) { 979#ifdef ASSERT 980 thread->verify_not_published(); 981#endif 982 983 // Allocate the OSThread object 984 OSThread* osthread = new OSThread(NULL, NULL); 985 986 if (osthread == NULL) { 987 return false; 988 } 989 990 // Store pthread info into the OSThread 991 osthread->set_thread_id(os::Linux::gettid()); 992 osthread->set_pthread_id(::pthread_self()); 993 994 // initialize floating point control register 995 os::Linux::init_thread_fpu_state(); 996 997 // Initial thread state is RUNNABLE 998 osthread->set_state(RUNNABLE); 999 1000 thread->set_osthread(osthread); 1001 1002 if (UseNUMA) { 1003 int lgrp_id = os::numa_get_group_id(); 1004 if (lgrp_id != -1) { 1005 thread->set_lgrp_id(lgrp_id); 1006 } 1007 } 1008 1009 if (os::Linux::is_initial_thread()) { 1010 // If current thread is initial thread, its stack is mapped on demand, 1011 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 1012 // the entire stack region to avoid SEGV in stack banging. 1013 // It is also useful to get around the heap-stack-gap problem on SuSE 1014 // kernel (see 4821821 for details). We first expand stack to the top 1015 // of yellow zone, then enable stack yellow zone (order is significant, 1016 // enabling yellow zone first will crash JVM on SuSE Linux), so there 1017 // is no gap between the last two virtual memory regions. 1018 1019 JavaThread *jt = (JavaThread *)thread; 1020 address addr = jt->stack_yellow_zone_base(); 1021 assert(addr != NULL, "initialization problem?"); 1022 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 1023 1024 osthread->set_expanding_stack(); 1025 os::Linux::manually_expand_stack(jt, addr); 1026 osthread->clear_expanding_stack(); 1027 } 1028 1029 // initialize signal mask for this thread 1030 // and save the caller's signal mask 1031 os::Linux::hotspot_sigmask(thread); 1032 1033 return true; 1034} 1035 1036void os::pd_start_thread(Thread* thread) { 1037 OSThread * osthread = thread->osthread(); 1038 assert(osthread->get_state() != INITIALIZED, "just checking"); 1039 Monitor* sync_with_child = osthread->startThread_lock(); 1040 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 1041 sync_with_child->notify(); 1042} 1043 1044// Free Linux resources related to the OSThread 1045void os::free_thread(OSThread* osthread) { 1046 assert(osthread != NULL, "osthread not set"); 1047 1048 if (Thread::current()->osthread() == osthread) { 1049 // Restore caller's signal mask 1050 sigset_t sigmask = osthread->caller_sigmask(); 1051 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1052 } 1053 1054 delete osthread; 1055} 1056 1057////////////////////////////////////////////////////////////////////////////// 1058// thread local storage 1059 1060int os::allocate_thread_local_storage() { 1061 pthread_key_t key; 1062 int rslt = pthread_key_create(&key, NULL); 1063 assert(rslt == 0, "cannot allocate thread local storage"); 1064 return (int)key; 1065} 1066 1067// Note: This is currently not used by VM, as we don't destroy TLS key 1068// on VM exit. 1069void os::free_thread_local_storage(int index) { 1070 int rslt = pthread_key_delete((pthread_key_t)index); 1071 assert(rslt == 0, "invalid index"); 1072} 1073 1074void os::thread_local_storage_at_put(int index, void* value) { 1075 int rslt = pthread_setspecific((pthread_key_t)index, value); 1076 assert(rslt == 0, "pthread_setspecific failed"); 1077} 1078 1079extern "C" Thread* get_thread() { 1080 return ThreadLocalStorage::thread(); 1081} 1082 1083////////////////////////////////////////////////////////////////////////////// 1084// initial thread 1085 1086// Check if current thread is the initial thread, similar to Solaris thr_main. 1087bool os::Linux::is_initial_thread(void) { 1088 char dummy; 1089 // If called before init complete, thread stack bottom will be null. 1090 // Can be called if fatal error occurs before initialization. 1091 if (initial_thread_stack_bottom() == NULL) return false; 1092 assert(initial_thread_stack_bottom() != NULL && 1093 initial_thread_stack_size() != 0, 1094 "os::init did not locate initial thread's stack region"); 1095 if ((address)&dummy >= initial_thread_stack_bottom() && 1096 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1097 return true; 1098 else return false; 1099} 1100 1101// Find the virtual memory area that contains addr 1102static bool find_vma(address addr, address* vma_low, address* vma_high) { 1103 FILE *fp = fopen("/proc/self/maps", "r"); 1104 if (fp) { 1105 address low, high; 1106 while (!feof(fp)) { 1107 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1108 if (low <= addr && addr < high) { 1109 if (vma_low) *vma_low = low; 1110 if (vma_high) *vma_high = high; 1111 fclose (fp); 1112 return true; 1113 } 1114 } 1115 for (;;) { 1116 int ch = fgetc(fp); 1117 if (ch == EOF || ch == (int)'\n') break; 1118 } 1119 } 1120 fclose(fp); 1121 } 1122 return false; 1123} 1124 1125// Locate initial thread stack. This special handling of initial thread stack 1126// is needed because pthread_getattr_np() on most (all?) Linux distros returns 1127// bogus value for initial thread. 1128void os::Linux::capture_initial_stack(size_t max_size) { 1129 // stack size is the easy part, get it from RLIMIT_STACK 1130 size_t stack_size; 1131 struct rlimit rlim; 1132 getrlimit(RLIMIT_STACK, &rlim); 1133 stack_size = rlim.rlim_cur; 1134 1135 // 6308388: a bug in ld.so will relocate its own .data section to the 1136 // lower end of primordial stack; reduce ulimit -s value a little bit 1137 // so we won't install guard page on ld.so's data section. 1138 stack_size -= 2 * page_size(); 1139 1140 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1141 // 7.1, in both cases we will get 2G in return value. 1142 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1143 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1144 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1145 // in case other parts in glibc still assumes 2M max stack size. 1146 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1147 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1148 if (stack_size > 2 * K * K IA64_ONLY(*2)) 1149 stack_size = 2 * K * K IA64_ONLY(*2); 1150 // Try to figure out where the stack base (top) is. This is harder. 1151 // 1152 // When an application is started, glibc saves the initial stack pointer in 1153 // a global variable "__libc_stack_end", which is then used by system 1154 // libraries. __libc_stack_end should be pretty close to stack top. The 1155 // variable is available since the very early days. However, because it is 1156 // a private interface, it could disappear in the future. 1157 // 1158 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1159 // to __libc_stack_end, it is very close to stack top, but isn't the real 1160 // stack top. Note that /proc may not exist if VM is running as a chroot 1161 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1162 // /proc/<pid>/stat could change in the future (though unlikely). 1163 // 1164 // We try __libc_stack_end first. If that doesn't work, look for 1165 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1166 // as a hint, which should work well in most cases. 1167 1168 uintptr_t stack_start; 1169 1170 // try __libc_stack_end first 1171 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1172 if (p && *p) { 1173 stack_start = *p; 1174 } else { 1175 // see if we can get the start_stack field from /proc/self/stat 1176 FILE *fp; 1177 int pid; 1178 char state; 1179 int ppid; 1180 int pgrp; 1181 int session; 1182 int nr; 1183 int tpgrp; 1184 unsigned long flags; 1185 unsigned long minflt; 1186 unsigned long cminflt; 1187 unsigned long majflt; 1188 unsigned long cmajflt; 1189 unsigned long utime; 1190 unsigned long stime; 1191 long cutime; 1192 long cstime; 1193 long prio; 1194 long nice; 1195 long junk; 1196 long it_real; 1197 uintptr_t start; 1198 uintptr_t vsize; 1199 intptr_t rss; 1200 uintptr_t rsslim; 1201 uintptr_t scodes; 1202 uintptr_t ecode; 1203 int i; 1204 1205 // Figure what the primordial thread stack base is. Code is inspired 1206 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1207 // followed by command name surrounded by parentheses, state, etc. 1208 char stat[2048]; 1209 int statlen; 1210 1211 fp = fopen("/proc/self/stat", "r"); 1212 if (fp) { 1213 statlen = fread(stat, 1, 2047, fp); 1214 stat[statlen] = '\0'; 1215 fclose(fp); 1216 1217 // Skip pid and the command string. Note that we could be dealing with 1218 // weird command names, e.g. user could decide to rename java launcher 1219 // to "java 1.4.2 :)", then the stat file would look like 1220 // 1234 (java 1.4.2 :)) R ... ... 1221 // We don't really need to know the command string, just find the last 1222 // occurrence of ")" and then start parsing from there. See bug 4726580. 1223 char * s = strrchr(stat, ')'); 1224 1225 i = 0; 1226 if (s) { 1227 // Skip blank chars 1228 do s++; while (isspace(*s)); 1229 1230#define _UFM UINTX_FORMAT 1231#define _DFM INTX_FORMAT 1232 1233 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1234 /* 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 */ 1235 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, 1236 &state, /* 3 %c */ 1237 &ppid, /* 4 %d */ 1238 &pgrp, /* 5 %d */ 1239 &session, /* 6 %d */ 1240 &nr, /* 7 %d */ 1241 &tpgrp, /* 8 %d */ 1242 &flags, /* 9 %lu */ 1243 &minflt, /* 10 %lu */ 1244 &cminflt, /* 11 %lu */ 1245 &majflt, /* 12 %lu */ 1246 &cmajflt, /* 13 %lu */ 1247 &utime, /* 14 %lu */ 1248 &stime, /* 15 %lu */ 1249 &cutime, /* 16 %ld */ 1250 &cstime, /* 17 %ld */ 1251 &prio, /* 18 %ld */ 1252 &nice, /* 19 %ld */ 1253 &junk, /* 20 %ld */ 1254 &it_real, /* 21 %ld */ 1255 &start, /* 22 UINTX_FORMAT */ 1256 &vsize, /* 23 UINTX_FORMAT */ 1257 &rss, /* 24 INTX_FORMAT */ 1258 &rsslim, /* 25 UINTX_FORMAT */ 1259 &scodes, /* 26 UINTX_FORMAT */ 1260 &ecode, /* 27 UINTX_FORMAT */ 1261 &stack_start); /* 28 UINTX_FORMAT */ 1262 } 1263 1264#undef _UFM 1265#undef _DFM 1266 1267 if (i != 28 - 2) { 1268 assert(false, "Bad conversion from /proc/self/stat"); 1269 // product mode - assume we are the initial thread, good luck in the 1270 // embedded case. 1271 warning("Can't detect initial thread stack location - bad conversion"); 1272 stack_start = (uintptr_t) &rlim; 1273 } 1274 } else { 1275 // For some reason we can't open /proc/self/stat (for example, running on 1276 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1277 // most cases, so don't abort: 1278 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1279 stack_start = (uintptr_t) &rlim; 1280 } 1281 } 1282 1283 // Now we have a pointer (stack_start) very close to the stack top, the 1284 // next thing to do is to figure out the exact location of stack top. We 1285 // can find out the virtual memory area that contains stack_start by 1286 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1287 // and its upper limit is the real stack top. (again, this would fail if 1288 // running inside chroot, because /proc may not exist.) 1289 1290 uintptr_t stack_top; 1291 address low, high; 1292 if (find_vma((address)stack_start, &low, &high)) { 1293 // success, "high" is the true stack top. (ignore "low", because initial 1294 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1295 stack_top = (uintptr_t)high; 1296 } else { 1297 // failed, likely because /proc/self/maps does not exist 1298 warning("Can't detect initial thread stack location - find_vma failed"); 1299 // best effort: stack_start is normally within a few pages below the real 1300 // stack top, use it as stack top, and reduce stack size so we won't put 1301 // guard page outside stack. 1302 stack_top = stack_start; 1303 stack_size -= 16 * page_size(); 1304 } 1305 1306 // stack_top could be partially down the page so align it 1307 stack_top = align_size_up(stack_top, page_size()); 1308 1309 if (max_size && stack_size > max_size) { 1310 _initial_thread_stack_size = max_size; 1311 } else { 1312 _initial_thread_stack_size = stack_size; 1313 } 1314 1315 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1316 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1317} 1318 1319//////////////////////////////////////////////////////////////////////////////// 1320// time support 1321 1322// Time since start-up in seconds to a fine granularity. 1323// Used by VMSelfDestructTimer and the MemProfiler. 1324double os::elapsedTime() { 1325 1326 return (double)(os::elapsed_counter()) * 0.000001; 1327} 1328 1329jlong os::elapsed_counter() { 1330 timeval time; 1331 int status = gettimeofday(&time, NULL); 1332 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count; 1333} 1334 1335jlong os::elapsed_frequency() { 1336 return (1000 * 1000); 1337} 1338 1339// For now, we say that linux does not support vtime. I have no idea 1340// whether it can actually be made to (DLD, 9/13/05). 1341 1342bool os::supports_vtime() { return false; } 1343bool os::enable_vtime() { return false; } 1344bool os::vtime_enabled() { return false; } 1345double os::elapsedVTime() { 1346 // better than nothing, but not much 1347 return elapsedTime(); 1348} 1349 1350jlong os::javaTimeMillis() { 1351 timeval time; 1352 int status = gettimeofday(&time, NULL); 1353 assert(status != -1, "linux error"); 1354 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1355} 1356 1357#ifndef CLOCK_MONOTONIC 1358#define CLOCK_MONOTONIC (1) 1359#endif 1360 1361void os::Linux::clock_init() { 1362 // we do dlopen's in this particular order due to bug in linux 1363 // dynamical loader (see 6348968) leading to crash on exit 1364 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1365 if (handle == NULL) { 1366 handle = dlopen("librt.so", RTLD_LAZY); 1367 } 1368 1369 if (handle) { 1370 int (*clock_getres_func)(clockid_t, struct timespec*) = 1371 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1372 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1373 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1374 if (clock_getres_func && clock_gettime_func) { 1375 // See if monotonic clock is supported by the kernel. Note that some 1376 // early implementations simply return kernel jiffies (updated every 1377 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1378 // for nano time (though the monotonic property is still nice to have). 1379 // It's fixed in newer kernels, however clock_getres() still returns 1380 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1381 // resolution for now. Hopefully as people move to new kernels, this 1382 // won't be a problem. 1383 struct timespec res; 1384 struct timespec tp; 1385 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1386 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1387 // yes, monotonic clock is supported 1388 _clock_gettime = clock_gettime_func; 1389 } else { 1390 // close librt if there is no monotonic clock 1391 dlclose(handle); 1392 } 1393 } 1394 } 1395} 1396 1397#ifndef SYS_clock_getres 1398 1399#if defined(IA32) || defined(AMD64) 1400#define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1401#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1402#else 1403#warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1404#define sys_clock_getres(x,y) -1 1405#endif 1406 1407#else 1408#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1409#endif 1410 1411void os::Linux::fast_thread_clock_init() { 1412 if (!UseLinuxPosixThreadCPUClocks) { 1413 return; 1414 } 1415 clockid_t clockid; 1416 struct timespec tp; 1417 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1418 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1419 1420 // Switch to using fast clocks for thread cpu time if 1421 // the sys_clock_getres() returns 0 error code. 1422 // Note, that some kernels may support the current thread 1423 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1424 // returned by the pthread_getcpuclockid(). 1425 // If the fast Posix clocks are supported then the sys_clock_getres() 1426 // must return at least tp.tv_sec == 0 which means a resolution 1427 // better than 1 sec. This is extra check for reliability. 1428 1429 if(pthread_getcpuclockid_func && 1430 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1431 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1432 1433 _supports_fast_thread_cpu_time = true; 1434 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1435 } 1436} 1437 1438jlong os::javaTimeNanos() { 1439 if (Linux::supports_monotonic_clock()) { 1440 struct timespec tp; 1441 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1442 assert(status == 0, "gettime error"); 1443 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1444 return result; 1445 } else { 1446 timeval time; 1447 int status = gettimeofday(&time, NULL); 1448 assert(status != -1, "linux error"); 1449 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1450 return 1000 * usecs; 1451 } 1452} 1453 1454void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1455 if (Linux::supports_monotonic_clock()) { 1456 info_ptr->max_value = ALL_64_BITS; 1457 1458 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1459 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1460 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1461 } else { 1462 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1463 info_ptr->max_value = ALL_64_BITS; 1464 1465 // gettimeofday is a real time clock so it skips 1466 info_ptr->may_skip_backward = true; 1467 info_ptr->may_skip_forward = true; 1468 } 1469 1470 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1471} 1472 1473// Return the real, user, and system times in seconds from an 1474// arbitrary fixed point in the past. 1475bool os::getTimesSecs(double* process_real_time, 1476 double* process_user_time, 1477 double* process_system_time) { 1478 struct tms ticks; 1479 clock_t real_ticks = times(&ticks); 1480 1481 if (real_ticks == (clock_t) (-1)) { 1482 return false; 1483 } else { 1484 double ticks_per_second = (double) clock_tics_per_sec; 1485 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1486 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1487 *process_real_time = ((double) real_ticks) / ticks_per_second; 1488 1489 return true; 1490 } 1491} 1492 1493 1494char * os::local_time_string(char *buf, size_t buflen) { 1495 struct tm t; 1496 time_t long_time; 1497 time(&long_time); 1498 localtime_r(&long_time, &t); 1499 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1500 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1501 t.tm_hour, t.tm_min, t.tm_sec); 1502 return buf; 1503} 1504 1505struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1506 return localtime_r(clock, res); 1507} 1508 1509//////////////////////////////////////////////////////////////////////////////// 1510// runtime exit support 1511 1512// Note: os::shutdown() might be called very early during initialization, or 1513// called from signal handler. Before adding something to os::shutdown(), make 1514// sure it is async-safe and can handle partially initialized VM. 1515void os::shutdown() { 1516 1517 // allow PerfMemory to attempt cleanup of any persistent resources 1518 perfMemory_exit(); 1519 1520 // needs to remove object in file system 1521 AttachListener::abort(); 1522 1523 // flush buffered output, finish log files 1524 ostream_abort(); 1525 1526 // Check for abort hook 1527 abort_hook_t abort_hook = Arguments::abort_hook(); 1528 if (abort_hook != NULL) { 1529 abort_hook(); 1530 } 1531 1532} 1533 1534// Note: os::abort() might be called very early during initialization, or 1535// called from signal handler. Before adding something to os::abort(), make 1536// sure it is async-safe and can handle partially initialized VM. 1537void os::abort(bool dump_core) { 1538 os::shutdown(); 1539 if (dump_core) { 1540#ifndef PRODUCT 1541 fdStream out(defaultStream::output_fd()); 1542 out.print_raw("Current thread is "); 1543 char buf[16]; 1544 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1545 out.print_raw_cr(buf); 1546 out.print_raw_cr("Dumping core ..."); 1547#endif 1548 ::abort(); // dump core 1549 } 1550 1551 ::exit(1); 1552} 1553 1554// Die immediately, no exit hook, no abort hook, no cleanup. 1555void os::die() { 1556 // _exit() on LinuxThreads only kills current thread 1557 ::abort(); 1558} 1559 1560// unused on linux for now. 1561void os::set_error_file(const char *logfile) {} 1562 1563 1564// This method is a copy of JDK's sysGetLastErrorString 1565// from src/solaris/hpi/src/system_md.c 1566 1567size_t os::lasterror(char *buf, size_t len) { 1568 1569 if (errno == 0) return 0; 1570 1571 const char *s = ::strerror(errno); 1572 size_t n = ::strlen(s); 1573 if (n >= len) { 1574 n = len - 1; 1575 } 1576 ::strncpy(buf, s, n); 1577 buf[n] = '\0'; 1578 return n; 1579} 1580 1581intx os::current_thread_id() { return (intx)pthread_self(); } 1582int os::current_process_id() { 1583 1584 // Under the old linux thread library, linux gives each thread 1585 // its own process id. Because of this each thread will return 1586 // a different pid if this method were to return the result 1587 // of getpid(2). Linux provides no api that returns the pid 1588 // of the launcher thread for the vm. This implementation 1589 // returns a unique pid, the pid of the launcher thread 1590 // that starts the vm 'process'. 1591 1592 // Under the NPTL, getpid() returns the same pid as the 1593 // launcher thread rather than a unique pid per thread. 1594 // Use gettid() if you want the old pre NPTL behaviour. 1595 1596 // if you are looking for the result of a call to getpid() that 1597 // returns a unique pid for the calling thread, then look at the 1598 // OSThread::thread_id() method in osThread_linux.hpp file 1599 1600 return (int)(_initial_pid ? _initial_pid : getpid()); 1601} 1602 1603// DLL functions 1604 1605const char* os::dll_file_extension() { return ".so"; } 1606 1607// This must be hard coded because it's the system's temporary 1608// directory not the java application's temp directory, ala java.io.tmpdir. 1609const char* os::get_temp_directory() { return "/tmp"; } 1610 1611static bool file_exists(const char* filename) { 1612 struct stat statbuf; 1613 if (filename == NULL || strlen(filename) == 0) { 1614 return false; 1615 } 1616 return os::stat(filename, &statbuf) == 0; 1617} 1618 1619bool os::dll_build_name(char* buffer, size_t buflen, 1620 const char* pname, const char* fname) { 1621 bool retval = false; 1622 // Copied from libhpi 1623 const size_t pnamelen = pname ? strlen(pname) : 0; 1624 1625 // Return error on buffer overflow. 1626 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1627 return retval; 1628 } 1629 1630 if (pnamelen == 0) { 1631 snprintf(buffer, buflen, "lib%s.so", fname); 1632 retval = true; 1633 } else if (strchr(pname, *os::path_separator()) != NULL) { 1634 int n; 1635 char** pelements = split_path(pname, &n); 1636 for (int i = 0 ; i < n ; i++) { 1637 // Really shouldn't be NULL, but check can't hurt 1638 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1639 continue; // skip the empty path values 1640 } 1641 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1642 if (file_exists(buffer)) { 1643 retval = true; 1644 break; 1645 } 1646 } 1647 // release the storage 1648 for (int i = 0 ; i < n ; i++) { 1649 if (pelements[i] != NULL) { 1650 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal); 1651 } 1652 } 1653 if (pelements != NULL) { 1654 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal); 1655 } 1656 } else { 1657 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1658 retval = true; 1659 } 1660 return retval; 1661} 1662 1663const char* os::get_current_directory(char *buf, int buflen) { 1664 return getcwd(buf, buflen); 1665} 1666 1667// check if addr is inside libjvm.so 1668bool os::address_is_in_vm(address addr) { 1669 static address libjvm_base_addr; 1670 Dl_info dlinfo; 1671 1672 if (libjvm_base_addr == NULL) { 1673 dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo); 1674 libjvm_base_addr = (address)dlinfo.dli_fbase; 1675 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1676 } 1677 1678 if (dladdr((void *)addr, &dlinfo)) { 1679 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1680 } 1681 1682 return false; 1683} 1684 1685bool os::dll_address_to_function_name(address addr, char *buf, 1686 int buflen, int *offset) { 1687 Dl_info dlinfo; 1688 1689 if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) { 1690 if (buf != NULL) { 1691 if(!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1692 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1693 } 1694 } 1695 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1696 return true; 1697 } else if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != 0) { 1698 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1699 buf, buflen, offset, dlinfo.dli_fname)) { 1700 return true; 1701 } 1702 } 1703 1704 if (buf != NULL) buf[0] = '\0'; 1705 if (offset != NULL) *offset = -1; 1706 return false; 1707} 1708 1709struct _address_to_library_name { 1710 address addr; // input : memory address 1711 size_t buflen; // size of fname 1712 char* fname; // output: library name 1713 address base; // library base addr 1714}; 1715 1716static int address_to_library_name_callback(struct dl_phdr_info *info, 1717 size_t size, void *data) { 1718 int i; 1719 bool found = false; 1720 address libbase = NULL; 1721 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1722 1723 // iterate through all loadable segments 1724 for (i = 0; i < info->dlpi_phnum; i++) { 1725 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1726 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1727 // base address of a library is the lowest address of its loaded 1728 // segments. 1729 if (libbase == NULL || libbase > segbase) { 1730 libbase = segbase; 1731 } 1732 // see if 'addr' is within current segment 1733 if (segbase <= d->addr && 1734 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1735 found = true; 1736 } 1737 } 1738 } 1739 1740 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1741 // so dll_address_to_library_name() can fall through to use dladdr() which 1742 // can figure out executable name from argv[0]. 1743 if (found && info->dlpi_name && info->dlpi_name[0]) { 1744 d->base = libbase; 1745 if (d->fname) { 1746 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1747 } 1748 return 1; 1749 } 1750 return 0; 1751} 1752 1753bool os::dll_address_to_library_name(address addr, char* buf, 1754 int buflen, int* offset) { 1755 Dl_info dlinfo; 1756 struct _address_to_library_name data; 1757 1758 // There is a bug in old glibc dladdr() implementation that it could resolve 1759 // to wrong library name if the .so file has a base address != NULL. Here 1760 // we iterate through the program headers of all loaded libraries to find 1761 // out which library 'addr' really belongs to. This workaround can be 1762 // removed once the minimum requirement for glibc is moved to 2.3.x. 1763 data.addr = addr; 1764 data.fname = buf; 1765 data.buflen = buflen; 1766 data.base = NULL; 1767 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1768 1769 if (rslt) { 1770 // buf already contains library name 1771 if (offset) *offset = addr - data.base; 1772 return true; 1773 } else if (dladdr((void*)addr, &dlinfo)){ 1774 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1775 if (offset) *offset = addr - (address)dlinfo.dli_fbase; 1776 return true; 1777 } else { 1778 if (buf) buf[0] = '\0'; 1779 if (offset) *offset = -1; 1780 return false; 1781 } 1782} 1783 1784 // Loads .dll/.so and 1785 // in case of error it checks if .dll/.so was built for the 1786 // same architecture as Hotspot is running on 1787 1788 1789// Remember the stack's state. The Linux dynamic linker will change 1790// the stack to 'executable' at most once, so we must safepoint only once. 1791bool os::Linux::_stack_is_executable = false; 1792 1793// VM operation that loads a library. This is necessary if stack protection 1794// of the Java stacks can be lost during loading the library. If we 1795// do not stop the Java threads, they can stack overflow before the stacks 1796// are protected again. 1797class VM_LinuxDllLoad: public VM_Operation { 1798 private: 1799 const char *_filename; 1800 char *_ebuf; 1801 int _ebuflen; 1802 void *_lib; 1803 public: 1804 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1805 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1806 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1807 void doit() { 1808 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1809 os::Linux::_stack_is_executable = true; 1810 } 1811 void* loaded_library() { return _lib; } 1812}; 1813 1814void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1815{ 1816 void * result = NULL; 1817 bool load_attempted = false; 1818 1819 // Check whether the library to load might change execution rights 1820 // of the stack. If they are changed, the protection of the stack 1821 // guard pages will be lost. We need a safepoint to fix this. 1822 // 1823 // See Linux man page execstack(8) for more info. 1824 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1825 ElfFile ef(filename); 1826 if (!ef.specifies_noexecstack()) { 1827 if (!is_init_completed()) { 1828 os::Linux::_stack_is_executable = true; 1829 // This is OK - No Java threads have been created yet, and hence no 1830 // stack guard pages to fix. 1831 // 1832 // This should happen only when you are building JDK7 using a very 1833 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1834 // 1835 // Dynamic loader will make all stacks executable after 1836 // this function returns, and will not do that again. 1837 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1838 } else { 1839 warning("You have loaded library %s which might have disabled stack guard. " 1840 "The VM will try to fix the stack guard now.\n" 1841 "It's highly recommended that you fix the library with " 1842 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1843 filename); 1844 1845 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1846 JavaThread *jt = JavaThread::current(); 1847 if (jt->thread_state() != _thread_in_native) { 1848 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1849 // that requires ExecStack. Cannot enter safe point. Let's give up. 1850 warning("Unable to fix stack guard. Giving up."); 1851 } else { 1852 if (!LoadExecStackDllInVMThread) { 1853 // This is for the case where the DLL has an static 1854 // constructor function that executes JNI code. We cannot 1855 // load such DLLs in the VMThread. 1856 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1857 } 1858 1859 ThreadInVMfromNative tiv(jt); 1860 debug_only(VMNativeEntryWrapper vew;) 1861 1862 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1863 VMThread::execute(&op); 1864 if (LoadExecStackDllInVMThread) { 1865 result = op.loaded_library(); 1866 } 1867 load_attempted = true; 1868 } 1869 } 1870 } 1871 } 1872 1873 if (!load_attempted) { 1874 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1875 } 1876 1877 if (result != NULL) { 1878 // Successful loading 1879 return result; 1880 } 1881 1882 Elf32_Ehdr elf_head; 1883 int diag_msg_max_length=ebuflen-strlen(ebuf); 1884 char* diag_msg_buf=ebuf+strlen(ebuf); 1885 1886 if (diag_msg_max_length==0) { 1887 // No more space in ebuf for additional diagnostics message 1888 return NULL; 1889 } 1890 1891 1892 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1893 1894 if (file_descriptor < 0) { 1895 // Can't open library, report dlerror() message 1896 return NULL; 1897 } 1898 1899 bool failed_to_read_elf_head= 1900 (sizeof(elf_head)!= 1901 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1902 1903 ::close(file_descriptor); 1904 if (failed_to_read_elf_head) { 1905 // file i/o error - report dlerror() msg 1906 return NULL; 1907 } 1908 1909 typedef struct { 1910 Elf32_Half code; // Actual value as defined in elf.h 1911 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1912 char elf_class; // 32 or 64 bit 1913 char endianess; // MSB or LSB 1914 char* name; // String representation 1915 } arch_t; 1916 1917 #ifndef EM_486 1918 #define EM_486 6 /* Intel 80486 */ 1919 #endif 1920 1921 static const arch_t arch_array[]={ 1922 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1923 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1924 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1925 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1926 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1927 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1928 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1929 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1930 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1931 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1932 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1933 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1934 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1935 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1936 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1937 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1938 }; 1939 1940 #if (defined IA32) 1941 static Elf32_Half running_arch_code=EM_386; 1942 #elif (defined AMD64) 1943 static Elf32_Half running_arch_code=EM_X86_64; 1944 #elif (defined IA64) 1945 static Elf32_Half running_arch_code=EM_IA_64; 1946 #elif (defined __sparc) && (defined _LP64) 1947 static Elf32_Half running_arch_code=EM_SPARCV9; 1948 #elif (defined __sparc) && (!defined _LP64) 1949 static Elf32_Half running_arch_code=EM_SPARC; 1950 #elif (defined __powerpc64__) 1951 static Elf32_Half running_arch_code=EM_PPC64; 1952 #elif (defined __powerpc__) 1953 static Elf32_Half running_arch_code=EM_PPC; 1954 #elif (defined ARM) 1955 static Elf32_Half running_arch_code=EM_ARM; 1956 #elif (defined S390) 1957 static Elf32_Half running_arch_code=EM_S390; 1958 #elif (defined ALPHA) 1959 static Elf32_Half running_arch_code=EM_ALPHA; 1960 #elif (defined MIPSEL) 1961 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1962 #elif (defined PARISC) 1963 static Elf32_Half running_arch_code=EM_PARISC; 1964 #elif (defined MIPS) 1965 static Elf32_Half running_arch_code=EM_MIPS; 1966 #elif (defined M68K) 1967 static Elf32_Half running_arch_code=EM_68K; 1968 #else 1969 #error Method os::dll_load requires that one of following is defined:\ 1970 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1971 #endif 1972 1973 // Identify compatability class for VM's architecture and library's architecture 1974 // Obtain string descriptions for architectures 1975 1976 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1977 int running_arch_index=-1; 1978 1979 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 1980 if (running_arch_code == arch_array[i].code) { 1981 running_arch_index = i; 1982 } 1983 if (lib_arch.code == arch_array[i].code) { 1984 lib_arch.compat_class = arch_array[i].compat_class; 1985 lib_arch.name = arch_array[i].name; 1986 } 1987 } 1988 1989 assert(running_arch_index != -1, 1990 "Didn't find running architecture code (running_arch_code) in arch_array"); 1991 if (running_arch_index == -1) { 1992 // Even though running architecture detection failed 1993 // we may still continue with reporting dlerror() message 1994 return NULL; 1995 } 1996 1997 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1998 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1999 return NULL; 2000 } 2001 2002#ifndef S390 2003 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 2004 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 2005 return NULL; 2006 } 2007#endif // !S390 2008 2009 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 2010 if ( lib_arch.name!=NULL ) { 2011 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2012 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 2013 lib_arch.name, arch_array[running_arch_index].name); 2014 } else { 2015 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2016 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 2017 lib_arch.code, 2018 arch_array[running_arch_index].name); 2019 } 2020 } 2021 2022 return NULL; 2023} 2024 2025void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) { 2026 void * result = ::dlopen(filename, RTLD_LAZY); 2027 if (result == NULL) { 2028 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2029 ebuf[ebuflen-1] = '\0'; 2030 } 2031 return result; 2032} 2033 2034void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) { 2035 void * result = NULL; 2036 if (LoadExecStackDllInVMThread) { 2037 result = dlopen_helper(filename, ebuf, ebuflen); 2038 } 2039 2040 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2041 // library that requires an executable stack, or which does not have this 2042 // stack attribute set, dlopen changes the stack attribute to executable. The 2043 // read protection of the guard pages gets lost. 2044 // 2045 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2046 // may have been queued at the same time. 2047 2048 if (!_stack_is_executable) { 2049 JavaThread *jt = Threads::first(); 2050 2051 while (jt) { 2052 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2053 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2054 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2055 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2056 warning("Attempt to reguard stack yellow zone failed."); 2057 } 2058 } 2059 jt = jt->next(); 2060 } 2061 } 2062 2063 return result; 2064} 2065 2066/* 2067 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2068 * chances are you might want to run the generated bits against glibc-2.0 2069 * libdl.so, so always use locking for any version of glibc. 2070 */ 2071void* os::dll_lookup(void* handle, const char* name) { 2072 pthread_mutex_lock(&dl_mutex); 2073 void* res = dlsym(handle, name); 2074 pthread_mutex_unlock(&dl_mutex); 2075 return res; 2076} 2077 2078 2079static bool _print_ascii_file(const char* filename, outputStream* st) { 2080 int fd = ::open(filename, O_RDONLY); 2081 if (fd == -1) { 2082 return false; 2083 } 2084 2085 char buf[32]; 2086 int bytes; 2087 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2088 st->print_raw(buf, bytes); 2089 } 2090 2091 ::close(fd); 2092 2093 return true; 2094} 2095 2096void os::print_dll_info(outputStream *st) { 2097 st->print_cr("Dynamic libraries:"); 2098 2099 char fname[32]; 2100 pid_t pid = os::Linux::gettid(); 2101 2102 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2103 2104 if (!_print_ascii_file(fname, st)) { 2105 st->print("Can not get library information for pid = %d\n", pid); 2106 } 2107} 2108 2109void os::print_os_info_brief(outputStream* st) { 2110 os::Linux::print_distro_info(st); 2111 2112 os::Posix::print_uname_info(st); 2113 2114 os::Linux::print_libversion_info(st); 2115 2116} 2117 2118void os::print_os_info(outputStream* st) { 2119 st->print("OS:"); 2120 2121 os::Linux::print_distro_info(st); 2122 2123 os::Posix::print_uname_info(st); 2124 2125 // Print warning if unsafe chroot environment detected 2126 if (unsafe_chroot_detected) { 2127 st->print("WARNING!! "); 2128 st->print_cr(unstable_chroot_error); 2129 } 2130 2131 os::Linux::print_libversion_info(st); 2132 2133 os::Posix::print_rlimit_info(st); 2134 2135 os::Posix::print_load_average(st); 2136 2137 os::Linux::print_full_memory_info(st); 2138} 2139 2140// Try to identify popular distros. 2141// Most Linux distributions have /etc/XXX-release file, which contains 2142// the OS version string. Some have more than one /etc/XXX-release file 2143// (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.), 2144// so the order is important. 2145void os::Linux::print_distro_info(outputStream* st) { 2146 if (!_print_ascii_file("/etc/mandrake-release", st) && 2147 !_print_ascii_file("/etc/sun-release", st) && 2148 !_print_ascii_file("/etc/redhat-release", st) && 2149 !_print_ascii_file("/etc/SuSE-release", st) && 2150 !_print_ascii_file("/etc/turbolinux-release", st) && 2151 !_print_ascii_file("/etc/gentoo-release", st) && 2152 !_print_ascii_file("/etc/debian_version", st) && 2153 !_print_ascii_file("/etc/ltib-release", st) && 2154 !_print_ascii_file("/etc/angstrom-version", st)) { 2155 st->print("Linux"); 2156 } 2157 st->cr(); 2158} 2159 2160void os::Linux::print_libversion_info(outputStream* st) { 2161 // libc, pthread 2162 st->print("libc:"); 2163 st->print(os::Linux::glibc_version()); st->print(" "); 2164 st->print(os::Linux::libpthread_version()); st->print(" "); 2165 if (os::Linux::is_LinuxThreads()) { 2166 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2167 } 2168 st->cr(); 2169} 2170 2171void os::Linux::print_full_memory_info(outputStream* st) { 2172 st->print("\n/proc/meminfo:\n"); 2173 _print_ascii_file("/proc/meminfo", st); 2174 st->cr(); 2175} 2176 2177void os::print_memory_info(outputStream* st) { 2178 2179 st->print("Memory:"); 2180 st->print(" %dk page", os::vm_page_size()>>10); 2181 2182 // values in struct sysinfo are "unsigned long" 2183 struct sysinfo si; 2184 sysinfo(&si); 2185 2186 st->print(", physical " UINT64_FORMAT "k", 2187 os::physical_memory() >> 10); 2188 st->print("(" UINT64_FORMAT "k free)", 2189 os::available_memory() >> 10); 2190 st->print(", swap " UINT64_FORMAT "k", 2191 ((jlong)si.totalswap * si.mem_unit) >> 10); 2192 st->print("(" UINT64_FORMAT "k free)", 2193 ((jlong)si.freeswap * si.mem_unit) >> 10); 2194 st->cr(); 2195} 2196 2197void os::pd_print_cpu_info(outputStream* st) { 2198 st->print("\n/proc/cpuinfo:\n"); 2199 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2200 st->print(" <Not Available>"); 2201 } 2202 st->cr(); 2203} 2204 2205// Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific 2206// but they're the same for all the linux arch that we support 2207// and they're the same for solaris but there's no common place to put this. 2208const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR", 2209 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG", 2210 "ILL_COPROC", "ILL_BADSTK" }; 2211 2212const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV", 2213 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES", 2214 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" }; 2215 2216const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" }; 2217 2218const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" }; 2219 2220void os::print_siginfo(outputStream* st, void* siginfo) { 2221 st->print("siginfo:"); 2222 2223 const int buflen = 100; 2224 char buf[buflen]; 2225 siginfo_t *si = (siginfo_t*)siginfo; 2226 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen)); 2227 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) { 2228 st->print("si_errno=%s", buf); 2229 } else { 2230 st->print("si_errno=%d", si->si_errno); 2231 } 2232 const int c = si->si_code; 2233 assert(c > 0, "unexpected si_code"); 2234 switch (si->si_signo) { 2235 case SIGILL: 2236 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]); 2237 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2238 break; 2239 case SIGFPE: 2240 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]); 2241 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2242 break; 2243 case SIGSEGV: 2244 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]); 2245 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2246 break; 2247 case SIGBUS: 2248 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]); 2249 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2250 break; 2251 default: 2252 st->print(", si_code=%d", si->si_code); 2253 // no si_addr 2254 } 2255 2256 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2257 UseSharedSpaces) { 2258 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2259 if (mapinfo->is_in_shared_space(si->si_addr)) { 2260 st->print("\n\nError accessing class data sharing archive." \ 2261 " Mapped file inaccessible during execution, " \ 2262 " possible disk/network problem."); 2263 } 2264 } 2265 st->cr(); 2266} 2267 2268 2269static void print_signal_handler(outputStream* st, int sig, 2270 char* buf, size_t buflen); 2271 2272void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2273 st->print_cr("Signal Handlers:"); 2274 print_signal_handler(st, SIGSEGV, buf, buflen); 2275 print_signal_handler(st, SIGBUS , buf, buflen); 2276 print_signal_handler(st, SIGFPE , buf, buflen); 2277 print_signal_handler(st, SIGPIPE, buf, buflen); 2278 print_signal_handler(st, SIGXFSZ, buf, buflen); 2279 print_signal_handler(st, SIGILL , buf, buflen); 2280 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2281 print_signal_handler(st, SR_signum, buf, buflen); 2282 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2283 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2284 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2285 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2286} 2287 2288static char saved_jvm_path[MAXPATHLEN] = {0}; 2289 2290// Find the full path to the current module, libjvm.so 2291void os::jvm_path(char *buf, jint buflen) { 2292 // Error checking. 2293 if (buflen < MAXPATHLEN) { 2294 assert(false, "must use a large-enough buffer"); 2295 buf[0] = '\0'; 2296 return; 2297 } 2298 // Lazy resolve the path to current module. 2299 if (saved_jvm_path[0] != 0) { 2300 strcpy(buf, saved_jvm_path); 2301 return; 2302 } 2303 2304 char dli_fname[MAXPATHLEN]; 2305 bool ret = dll_address_to_library_name( 2306 CAST_FROM_FN_PTR(address, os::jvm_path), 2307 dli_fname, sizeof(dli_fname), NULL); 2308 assert(ret != 0, "cannot locate libjvm"); 2309 char *rp = realpath(dli_fname, buf); 2310 if (rp == NULL) 2311 return; 2312 2313 if (Arguments::created_by_gamma_launcher()) { 2314 // Support for the gamma launcher. Typical value for buf is 2315 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at 2316 // the right place in the string, then assume we are installed in a JDK and 2317 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix 2318 // up the path so it looks like libjvm.so is installed there (append a 2319 // fake suffix hotspot/libjvm.so). 2320 const char *p = buf + strlen(buf) - 1; 2321 for (int count = 0; p > buf && count < 5; ++count) { 2322 for (--p; p > buf && *p != '/'; --p) 2323 /* empty */ ; 2324 } 2325 2326 if (strncmp(p, "/jre/lib/", 9) != 0) { 2327 // Look for JAVA_HOME in the environment. 2328 char* java_home_var = ::getenv("JAVA_HOME"); 2329 if (java_home_var != NULL && java_home_var[0] != 0) { 2330 char* jrelib_p; 2331 int len; 2332 2333 // Check the current module name "libjvm.so". 2334 p = strrchr(buf, '/'); 2335 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2336 2337 rp = realpath(java_home_var, buf); 2338 if (rp == NULL) 2339 return; 2340 2341 // determine if this is a legacy image or modules image 2342 // modules image doesn't have "jre" subdirectory 2343 len = strlen(buf); 2344 jrelib_p = buf + len; 2345 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2346 if (0 != access(buf, F_OK)) { 2347 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2348 } 2349 2350 if (0 == access(buf, F_OK)) { 2351 // Use current module name "libjvm.so" 2352 len = strlen(buf); 2353 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2354 } else { 2355 // Go back to path of .so 2356 rp = realpath(dli_fname, buf); 2357 if (rp == NULL) 2358 return; 2359 } 2360 } 2361 } 2362 } 2363 2364 strcpy(saved_jvm_path, buf); 2365} 2366 2367void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2368 // no prefix required, not even "_" 2369} 2370 2371void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2372 // no suffix required 2373} 2374 2375//////////////////////////////////////////////////////////////////////////////// 2376// sun.misc.Signal support 2377 2378static volatile jint sigint_count = 0; 2379 2380static void 2381UserHandler(int sig, void *siginfo, void *context) { 2382 // 4511530 - sem_post is serialized and handled by the manager thread. When 2383 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2384 // don't want to flood the manager thread with sem_post requests. 2385 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2386 return; 2387 2388 // Ctrl-C is pressed during error reporting, likely because the error 2389 // handler fails to abort. Let VM die immediately. 2390 if (sig == SIGINT && is_error_reported()) { 2391 os::die(); 2392 } 2393 2394 os::signal_notify(sig); 2395} 2396 2397void* os::user_handler() { 2398 return CAST_FROM_FN_PTR(void*, UserHandler); 2399} 2400 2401extern "C" { 2402 typedef void (*sa_handler_t)(int); 2403 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2404} 2405 2406void* os::signal(int signal_number, void* handler) { 2407 struct sigaction sigAct, oldSigAct; 2408 2409 sigfillset(&(sigAct.sa_mask)); 2410 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2411 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2412 2413 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2414 // -1 means registration failed 2415 return (void *)-1; 2416 } 2417 2418 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2419} 2420 2421void os::signal_raise(int signal_number) { 2422 ::raise(signal_number); 2423} 2424 2425/* 2426 * The following code is moved from os.cpp for making this 2427 * code platform specific, which it is by its very nature. 2428 */ 2429 2430// Will be modified when max signal is changed to be dynamic 2431int os::sigexitnum_pd() { 2432 return NSIG; 2433} 2434 2435// a counter for each possible signal value 2436static volatile jint pending_signals[NSIG+1] = { 0 }; 2437 2438// Linux(POSIX) specific hand shaking semaphore. 2439static sem_t sig_sem; 2440 2441void os::signal_init_pd() { 2442 // Initialize signal structures 2443 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2444 2445 // Initialize signal semaphore 2446 ::sem_init(&sig_sem, 0, 0); 2447} 2448 2449void os::signal_notify(int sig) { 2450 Atomic::inc(&pending_signals[sig]); 2451 ::sem_post(&sig_sem); 2452} 2453 2454static int check_pending_signals(bool wait) { 2455 Atomic::store(0, &sigint_count); 2456 for (;;) { 2457 for (int i = 0; i < NSIG + 1; i++) { 2458 jint n = pending_signals[i]; 2459 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2460 return i; 2461 } 2462 } 2463 if (!wait) { 2464 return -1; 2465 } 2466 JavaThread *thread = JavaThread::current(); 2467 ThreadBlockInVM tbivm(thread); 2468 2469 bool threadIsSuspended; 2470 do { 2471 thread->set_suspend_equivalent(); 2472 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2473 ::sem_wait(&sig_sem); 2474 2475 // were we externally suspended while we were waiting? 2476 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2477 if (threadIsSuspended) { 2478 // 2479 // The semaphore has been incremented, but while we were waiting 2480 // another thread suspended us. We don't want to continue running 2481 // while suspended because that would surprise the thread that 2482 // suspended us. 2483 // 2484 ::sem_post(&sig_sem); 2485 2486 thread->java_suspend_self(); 2487 } 2488 } while (threadIsSuspended); 2489 } 2490} 2491 2492int os::signal_lookup() { 2493 return check_pending_signals(false); 2494} 2495 2496int os::signal_wait() { 2497 return check_pending_signals(true); 2498} 2499 2500//////////////////////////////////////////////////////////////////////////////// 2501// Virtual Memory 2502 2503int os::vm_page_size() { 2504 // Seems redundant as all get out 2505 assert(os::Linux::page_size() != -1, "must call os::init"); 2506 return os::Linux::page_size(); 2507} 2508 2509// Solaris allocates memory by pages. 2510int os::vm_allocation_granularity() { 2511 assert(os::Linux::page_size() != -1, "must call os::init"); 2512 return os::Linux::page_size(); 2513} 2514 2515// Rationale behind this function: 2516// current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2517// mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2518// samples for JITted code. Here we create private executable mapping over the code cache 2519// and then we can use standard (well, almost, as mapping can change) way to provide 2520// info for the reporting script by storing timestamp and location of symbol 2521void linux_wrap_code(char* base, size_t size) { 2522 static volatile jint cnt = 0; 2523 2524 if (!UseOprofile) { 2525 return; 2526 } 2527 2528 char buf[PATH_MAX+1]; 2529 int num = Atomic::add(1, &cnt); 2530 2531 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2532 os::get_temp_directory(), os::current_process_id(), num); 2533 unlink(buf); 2534 2535 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2536 2537 if (fd != -1) { 2538 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2539 if (rv != (off_t)-1) { 2540 if (::write(fd, "", 1) == 1) { 2541 mmap(base, size, 2542 PROT_READ|PROT_WRITE|PROT_EXEC, 2543 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2544 } 2545 } 2546 ::close(fd); 2547 unlink(buf); 2548 } 2549} 2550 2551// NOTE: Linux kernel does not really reserve the pages for us. 2552// All it does is to check if there are enough free pages 2553// left at the time of mmap(). This could be a potential 2554// problem. 2555bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2556 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2557 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2558 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2559 if (res != (uintptr_t) MAP_FAILED) { 2560 if (UseNUMAInterleaving) { 2561 numa_make_global(addr, size); 2562 } 2563 return true; 2564 } 2565 return false; 2566} 2567 2568// Define MAP_HUGETLB here so we can build HotSpot on old systems. 2569#ifndef MAP_HUGETLB 2570#define MAP_HUGETLB 0x40000 2571#endif 2572 2573// Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2574#ifndef MADV_HUGEPAGE 2575#define MADV_HUGEPAGE 14 2576#endif 2577 2578bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2579 bool exec) { 2580 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) { 2581 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2582 uintptr_t res = 2583 (uintptr_t) ::mmap(addr, size, prot, 2584 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_HUGETLB, 2585 -1, 0); 2586 if (res != (uintptr_t) MAP_FAILED) { 2587 if (UseNUMAInterleaving) { 2588 numa_make_global(addr, size); 2589 } 2590 return true; 2591 } 2592 // Fall through and try to use small pages 2593 } 2594 2595 if (commit_memory(addr, size, exec)) { 2596 realign_memory(addr, size, alignment_hint); 2597 return true; 2598 } 2599 return false; 2600} 2601 2602void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2603 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) { 2604 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2605 // be supported or the memory may already be backed by huge pages. 2606 ::madvise(addr, bytes, MADV_HUGEPAGE); 2607 } 2608} 2609 2610void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2611 // This method works by doing an mmap over an existing mmaping and effectively discarding 2612 // the existing pages. However it won't work for SHM-based large pages that cannot be 2613 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2614 // small pages on top of the SHM segment. This method always works for small pages, so we 2615 // allow that in any case. 2616 if (alignment_hint <= (size_t)os::vm_page_size() || !UseSHM) { 2617 commit_memory(addr, bytes, alignment_hint, false); 2618 } 2619} 2620 2621void os::numa_make_global(char *addr, size_t bytes) { 2622 Linux::numa_interleave_memory(addr, bytes); 2623} 2624 2625void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2626 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2627} 2628 2629bool os::numa_topology_changed() { return false; } 2630 2631size_t os::numa_get_groups_num() { 2632 int max_node = Linux::numa_max_node(); 2633 return max_node > 0 ? max_node + 1 : 1; 2634} 2635 2636int os::numa_get_group_id() { 2637 int cpu_id = Linux::sched_getcpu(); 2638 if (cpu_id != -1) { 2639 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2640 if (lgrp_id != -1) { 2641 return lgrp_id; 2642 } 2643 } 2644 return 0; 2645} 2646 2647size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2648 for (size_t i = 0; i < size; i++) { 2649 ids[i] = i; 2650 } 2651 return size; 2652} 2653 2654bool os::get_page_info(char *start, page_info* info) { 2655 return false; 2656} 2657 2658char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2659 return end; 2660} 2661 2662 2663int os::Linux::sched_getcpu_syscall(void) { 2664 unsigned int cpu; 2665 int retval = -1; 2666 2667#if defined(IA32) 2668# ifndef SYS_getcpu 2669# define SYS_getcpu 318 2670# endif 2671 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2672#elif defined(AMD64) 2673// Unfortunately we have to bring all these macros here from vsyscall.h 2674// to be able to compile on old linuxes. 2675# define __NR_vgetcpu 2 2676# define VSYSCALL_START (-10UL << 20) 2677# define VSYSCALL_SIZE 1024 2678# define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2679 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2680 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2681 retval = vgetcpu(&cpu, NULL, NULL); 2682#endif 2683 2684 return (retval == -1) ? retval : cpu; 2685} 2686 2687// Something to do with the numa-aware allocator needs these symbols 2688extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2689extern "C" JNIEXPORT void numa_error(char *where) { } 2690extern "C" JNIEXPORT int fork1() { return fork(); } 2691 2692 2693// If we are running with libnuma version > 2, then we should 2694// be trying to use symbols with versions 1.1 2695// If we are running with earlier version, which did not have symbol versions, 2696// we should use the base version. 2697void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2698 void *f = dlvsym(handle, name, "libnuma_1.1"); 2699 if (f == NULL) { 2700 f = dlsym(handle, name); 2701 } 2702 return f; 2703} 2704 2705bool os::Linux::libnuma_init() { 2706 // sched_getcpu() should be in libc. 2707 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2708 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2709 2710 // If it's not, try a direct syscall. 2711 if (sched_getcpu() == -1) 2712 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall)); 2713 2714 if (sched_getcpu() != -1) { // Does it work? 2715 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2716 if (handle != NULL) { 2717 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2718 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2719 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2720 libnuma_dlsym(handle, "numa_max_node"))); 2721 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2722 libnuma_dlsym(handle, "numa_available"))); 2723 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2724 libnuma_dlsym(handle, "numa_tonode_memory"))); 2725 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2726 libnuma_dlsym(handle, "numa_interleave_memory"))); 2727 2728 2729 if (numa_available() != -1) { 2730 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2731 // Create a cpu -> node mapping 2732 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2733 rebuild_cpu_to_node_map(); 2734 return true; 2735 } 2736 } 2737 } 2738 return false; 2739} 2740 2741// rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2742// The table is later used in get_node_by_cpu(). 2743void os::Linux::rebuild_cpu_to_node_map() { 2744 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2745 // in libnuma (possible values are starting from 16, 2746 // and continuing up with every other power of 2, but less 2747 // than the maximum number of CPUs supported by kernel), and 2748 // is a subject to change (in libnuma version 2 the requirements 2749 // are more reasonable) we'll just hardcode the number they use 2750 // in the library. 2751 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2752 2753 size_t cpu_num = os::active_processor_count(); 2754 size_t cpu_map_size = NCPUS / BitsPerCLong; 2755 size_t cpu_map_valid_size = 2756 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2757 2758 cpu_to_node()->clear(); 2759 cpu_to_node()->at_grow(cpu_num - 1); 2760 size_t node_num = numa_get_groups_num(); 2761 2762 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2763 for (size_t i = 0; i < node_num; i++) { 2764 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2765 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2766 if (cpu_map[j] != 0) { 2767 for (size_t k = 0; k < BitsPerCLong; k++) { 2768 if (cpu_map[j] & (1UL << k)) { 2769 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2770 } 2771 } 2772 } 2773 } 2774 } 2775 } 2776 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal); 2777} 2778 2779int os::Linux::get_node_by_cpu(int cpu_id) { 2780 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2781 return cpu_to_node()->at(cpu_id); 2782 } 2783 return -1; 2784} 2785 2786GrowableArray<int>* os::Linux::_cpu_to_node; 2787os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2788os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2789os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2790os::Linux::numa_available_func_t os::Linux::_numa_available; 2791os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2792os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2793unsigned long* os::Linux::_numa_all_nodes; 2794 2795bool os::pd_uncommit_memory(char* addr, size_t size) { 2796 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2797 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2798 return res != (uintptr_t) MAP_FAILED; 2799} 2800 2801// Linux uses a growable mapping for the stack, and if the mapping for 2802// the stack guard pages is not removed when we detach a thread the 2803// stack cannot grow beyond the pages where the stack guard was 2804// mapped. If at some point later in the process the stack expands to 2805// that point, the Linux kernel cannot expand the stack any further 2806// because the guard pages are in the way, and a segfault occurs. 2807// 2808// However, it's essential not to split the stack region by unmapping 2809// a region (leaving a hole) that's already part of the stack mapping, 2810// so if the stack mapping has already grown beyond the guard pages at 2811// the time we create them, we have to truncate the stack mapping. 2812// So, we need to know the extent of the stack mapping when 2813// create_stack_guard_pages() is called. 2814 2815// Find the bounds of the stack mapping. Return true for success. 2816// 2817// We only need this for stacks that are growable: at the time of 2818// writing thread stacks don't use growable mappings (i.e. those 2819// creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 2820// only applies to the main thread. 2821 2822static 2823bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) { 2824 2825 char buf[128]; 2826 int fd, sz; 2827 2828 if ((fd = ::open("/proc/self/maps", O_RDONLY)) < 0) { 2829 return false; 2830 } 2831 2832 const char kw[] = "[stack]"; 2833 const int kwlen = sizeof(kw)-1; 2834 2835 // Address part of /proc/self/maps couldn't be more than 128 bytes 2836 while ((sz = os::get_line_chars(fd, buf, sizeof(buf))) > 0) { 2837 if (sz > kwlen && ::memcmp(buf+sz-kwlen, kw, kwlen) == 0) { 2838 // Extract addresses 2839 if (sscanf(buf, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) { 2840 uintptr_t sp = (uintptr_t) __builtin_frame_address(0); 2841 if (sp >= *bottom && sp <= *top) { 2842 ::close(fd); 2843 return true; 2844 } 2845 } 2846 } 2847 } 2848 2849 ::close(fd); 2850 return false; 2851} 2852 2853 2854// If the (growable) stack mapping already extends beyond the point 2855// where we're going to put our guard pages, truncate the mapping at 2856// that point by munmap()ping it. This ensures that when we later 2857// munmap() the guard pages we don't leave a hole in the stack 2858// mapping. This only affects the main/initial thread, but guard 2859// against future OS changes 2860bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 2861 uintptr_t stack_extent, stack_base; 2862 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true); 2863 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) { 2864 assert(os::Linux::is_initial_thread(), 2865 "growable stack in non-initial thread"); 2866 if (stack_extent < (uintptr_t)addr) 2867 ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent); 2868 } 2869 2870 return os::commit_memory(addr, size); 2871} 2872 2873// If this is a growable mapping, remove the guard pages entirely by 2874// munmap()ping them. If not, just call uncommit_memory(). This only 2875// affects the main/initial thread, but guard against future OS changes 2876bool os::remove_stack_guard_pages(char* addr, size_t size) { 2877 uintptr_t stack_extent, stack_base; 2878 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true); 2879 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) { 2880 assert(os::Linux::is_initial_thread(), 2881 "growable stack in non-initial thread"); 2882 2883 return ::munmap(addr, size) == 0; 2884 } 2885 2886 return os::uncommit_memory(addr, size); 2887} 2888 2889static address _highest_vm_reserved_address = NULL; 2890 2891// If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 2892// at 'requested_addr'. If there are existing memory mappings at the same 2893// location, however, they will be overwritten. If 'fixed' is false, 2894// 'requested_addr' is only treated as a hint, the return value may or 2895// may not start from the requested address. Unlike Linux mmap(), this 2896// function returns NULL to indicate failure. 2897static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 2898 char * addr; 2899 int flags; 2900 2901 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 2902 if (fixed) { 2903 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 2904 flags |= MAP_FIXED; 2905 } 2906 2907 // Map uncommitted pages PROT_READ and PROT_WRITE, change access 2908 // to PROT_EXEC if executable when we commit the page. 2909 addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE, 2910 flags, -1, 0); 2911 2912 if (addr != MAP_FAILED) { 2913 // anon_mmap() should only get called during VM initialization, 2914 // don't need lock (actually we can skip locking even it can be called 2915 // from multiple threads, because _highest_vm_reserved_address is just a 2916 // hint about the upper limit of non-stack memory regions.) 2917 if ((address)addr + bytes > _highest_vm_reserved_address) { 2918 _highest_vm_reserved_address = (address)addr + bytes; 2919 } 2920 } 2921 2922 return addr == MAP_FAILED ? NULL : addr; 2923} 2924 2925// Don't update _highest_vm_reserved_address, because there might be memory 2926// regions above addr + size. If so, releasing a memory region only creates 2927// a hole in the address space, it doesn't help prevent heap-stack collision. 2928// 2929static int anon_munmap(char * addr, size_t size) { 2930 return ::munmap(addr, size) == 0; 2931} 2932 2933char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 2934 size_t alignment_hint) { 2935 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 2936} 2937 2938bool os::pd_release_memory(char* addr, size_t size) { 2939 return anon_munmap(addr, size); 2940} 2941 2942static address highest_vm_reserved_address() { 2943 return _highest_vm_reserved_address; 2944} 2945 2946static bool linux_mprotect(char* addr, size_t size, int prot) { 2947 // Linux wants the mprotect address argument to be page aligned. 2948 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 2949 2950 // According to SUSv3, mprotect() should only be used with mappings 2951 // established by mmap(), and mmap() always maps whole pages. Unaligned 2952 // 'addr' likely indicates problem in the VM (e.g. trying to change 2953 // protection of malloc'ed or statically allocated memory). Check the 2954 // caller if you hit this assert. 2955 assert(addr == bottom, "sanity check"); 2956 2957 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 2958 return ::mprotect(bottom, size, prot) == 0; 2959} 2960 2961// Set protections specified 2962bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 2963 bool is_committed) { 2964 unsigned int p = 0; 2965 switch (prot) { 2966 case MEM_PROT_NONE: p = PROT_NONE; break; 2967 case MEM_PROT_READ: p = PROT_READ; break; 2968 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 2969 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 2970 default: 2971 ShouldNotReachHere(); 2972 } 2973 // is_committed is unused. 2974 return linux_mprotect(addr, bytes, p); 2975} 2976 2977bool os::guard_memory(char* addr, size_t size) { 2978 return linux_mprotect(addr, size, PROT_NONE); 2979} 2980 2981bool os::unguard_memory(char* addr, size_t size) { 2982 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 2983} 2984 2985bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 2986 bool result = false; 2987 void *p = mmap (NULL, page_size, PROT_READ|PROT_WRITE, 2988 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 2989 -1, 0); 2990 2991 if (p != (void *) -1) { 2992 // We don't know if this really is a huge page or not. 2993 FILE *fp = fopen("/proc/self/maps", "r"); 2994 if (fp) { 2995 while (!feof(fp)) { 2996 char chars[257]; 2997 long x = 0; 2998 if (fgets(chars, sizeof(chars), fp)) { 2999 if (sscanf(chars, "%lx-%*x", &x) == 1 3000 && x == (long)p) { 3001 if (strstr (chars, "hugepage")) { 3002 result = true; 3003 break; 3004 } 3005 } 3006 } 3007 } 3008 fclose(fp); 3009 } 3010 munmap (p, page_size); 3011 if (result) 3012 return true; 3013 } 3014 3015 if (warn) { 3016 warning("HugeTLBFS is not supported by the operating system."); 3017 } 3018 3019 return result; 3020} 3021 3022/* 3023* Set the coredump_filter bits to include largepages in core dump (bit 6) 3024* 3025* From the coredump_filter documentation: 3026* 3027* - (bit 0) anonymous private memory 3028* - (bit 1) anonymous shared memory 3029* - (bit 2) file-backed private memory 3030* - (bit 3) file-backed shared memory 3031* - (bit 4) ELF header pages in file-backed private memory areas (it is 3032* effective only if the bit 2 is cleared) 3033* - (bit 5) hugetlb private memory 3034* - (bit 6) hugetlb shared memory 3035*/ 3036static void set_coredump_filter(void) { 3037 FILE *f; 3038 long cdm; 3039 3040 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3041 return; 3042 } 3043 3044 if (fscanf(f, "%lx", &cdm) != 1) { 3045 fclose(f); 3046 return; 3047 } 3048 3049 rewind(f); 3050 3051 if ((cdm & LARGEPAGES_BIT) == 0) { 3052 cdm |= LARGEPAGES_BIT; 3053 fprintf(f, "%#lx", cdm); 3054 } 3055 3056 fclose(f); 3057} 3058 3059// Large page support 3060 3061static size_t _large_page_size = 0; 3062 3063void os::large_page_init() { 3064 if (!UseLargePages) { 3065 UseHugeTLBFS = false; 3066 UseSHM = false; 3067 return; 3068 } 3069 3070 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && FLAG_IS_DEFAULT(UseSHM)) { 3071 // If UseLargePages is specified on the command line try both methods, 3072 // if it's default, then try only HugeTLBFS. 3073 if (FLAG_IS_DEFAULT(UseLargePages)) { 3074 UseHugeTLBFS = true; 3075 } else { 3076 UseHugeTLBFS = UseSHM = true; 3077 } 3078 } 3079 3080 if (LargePageSizeInBytes) { 3081 _large_page_size = LargePageSizeInBytes; 3082 } else { 3083 // large_page_size on Linux is used to round up heap size. x86 uses either 3084 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3085 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3086 // page as large as 256M. 3087 // 3088 // Here we try to figure out page size by parsing /proc/meminfo and looking 3089 // for a line with the following format: 3090 // Hugepagesize: 2048 kB 3091 // 3092 // If we can't determine the value (e.g. /proc is not mounted, or the text 3093 // format has been changed), we'll use the largest page size supported by 3094 // the processor. 3095 3096#ifndef ZERO 3097 _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3098 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3099#endif // ZERO 3100 3101 FILE *fp = fopen("/proc/meminfo", "r"); 3102 if (fp) { 3103 while (!feof(fp)) { 3104 int x = 0; 3105 char buf[16]; 3106 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3107 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3108 _large_page_size = x * K; 3109 break; 3110 } 3111 } else { 3112 // skip to next line 3113 for (;;) { 3114 int ch = fgetc(fp); 3115 if (ch == EOF || ch == (int)'\n') break; 3116 } 3117 } 3118 } 3119 fclose(fp); 3120 } 3121 } 3122 3123 // print a warning if any large page related flag is specified on command line 3124 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3125 3126 const size_t default_page_size = (size_t)Linux::page_size(); 3127 if (_large_page_size > default_page_size) { 3128 _page_sizes[0] = _large_page_size; 3129 _page_sizes[1] = default_page_size; 3130 _page_sizes[2] = 0; 3131 } 3132 UseHugeTLBFS = UseHugeTLBFS && 3133 Linux::hugetlbfs_sanity_check(warn_on_failure, _large_page_size); 3134 3135 if (UseHugeTLBFS) 3136 UseSHM = false; 3137 3138 UseLargePages = UseHugeTLBFS || UseSHM; 3139 3140 set_coredump_filter(); 3141} 3142 3143#ifndef SHM_HUGETLB 3144#define SHM_HUGETLB 04000 3145#endif 3146 3147char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) { 3148 // "exec" is passed in but not used. Creating the shared image for 3149 // the code cache doesn't have an SHM_X executable permission to check. 3150 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3151 3152 key_t key = IPC_PRIVATE; 3153 char *addr; 3154 3155 bool warn_on_failure = UseLargePages && 3156 (!FLAG_IS_DEFAULT(UseLargePages) || 3157 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 3158 ); 3159 char msg[128]; 3160 3161 // Create a large shared memory region to attach to based on size. 3162 // Currently, size is the total size of the heap 3163 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3164 if (shmid == -1) { 3165 // Possible reasons for shmget failure: 3166 // 1. shmmax is too small for Java heap. 3167 // > check shmmax value: cat /proc/sys/kernel/shmmax 3168 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3169 // 2. not enough large page memory. 3170 // > check available large pages: cat /proc/meminfo 3171 // > increase amount of large pages: 3172 // echo new_value > /proc/sys/vm/nr_hugepages 3173 // Note 1: different Linux may use different name for this property, 3174 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3175 // Note 2: it's possible there's enough physical memory available but 3176 // they are so fragmented after a long run that they can't 3177 // coalesce into large pages. Try to reserve large pages when 3178 // the system is still "fresh". 3179 if (warn_on_failure) { 3180 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3181 warning(msg); 3182 } 3183 return NULL; 3184 } 3185 3186 // attach to the region 3187 addr = (char*)shmat(shmid, req_addr, 0); 3188 int err = errno; 3189 3190 // Remove shmid. If shmat() is successful, the actual shared memory segment 3191 // will be deleted when it's detached by shmdt() or when the process 3192 // terminates. If shmat() is not successful this will remove the shared 3193 // segment immediately. 3194 shmctl(shmid, IPC_RMID, NULL); 3195 3196 if ((intptr_t)addr == -1) { 3197 if (warn_on_failure) { 3198 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3199 warning(msg); 3200 } 3201 return NULL; 3202 } 3203 3204 if ((addr != NULL) && UseNUMAInterleaving) { 3205 numa_make_global(addr, bytes); 3206 } 3207 3208 // The memory is committed 3209 address pc = CALLER_PC; 3210 MemTracker::record_virtual_memory_reserve((address)addr, bytes, pc); 3211 MemTracker::record_virtual_memory_commit((address)addr, bytes, pc); 3212 3213 return addr; 3214} 3215 3216bool os::release_memory_special(char* base, size_t bytes) { 3217 // detaching the SHM segment will also delete it, see reserve_memory_special() 3218 int rslt = shmdt(base); 3219 if (rslt == 0) { 3220 MemTracker::record_virtual_memory_uncommit((address)base, bytes); 3221 MemTracker::record_virtual_memory_release((address)base, bytes); 3222 return true; 3223 } else { 3224 return false; 3225 } 3226} 3227 3228size_t os::large_page_size() { 3229 return _large_page_size; 3230} 3231 3232// HugeTLBFS allows application to commit large page memory on demand; 3233// with SysV SHM the entire memory region must be allocated as shared 3234// memory. 3235bool os::can_commit_large_page_memory() { 3236 return UseHugeTLBFS; 3237} 3238 3239bool os::can_execute_large_page_memory() { 3240 return UseHugeTLBFS; 3241} 3242 3243// Reserve memory at an arbitrary address, only if that area is 3244// available (and not reserved for something else). 3245 3246char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3247 const int max_tries = 10; 3248 char* base[max_tries]; 3249 size_t size[max_tries]; 3250 const size_t gap = 0x000000; 3251 3252 // Assert only that the size is a multiple of the page size, since 3253 // that's all that mmap requires, and since that's all we really know 3254 // about at this low abstraction level. If we need higher alignment, 3255 // we can either pass an alignment to this method or verify alignment 3256 // in one of the methods further up the call chain. See bug 5044738. 3257 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3258 3259 // Repeatedly allocate blocks until the block is allocated at the 3260 // right spot. Give up after max_tries. Note that reserve_memory() will 3261 // automatically update _highest_vm_reserved_address if the call is 3262 // successful. The variable tracks the highest memory address every reserved 3263 // by JVM. It is used to detect heap-stack collision if running with 3264 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3265 // space than needed, it could confuse the collision detecting code. To 3266 // solve the problem, save current _highest_vm_reserved_address and 3267 // calculate the correct value before return. 3268 address old_highest = _highest_vm_reserved_address; 3269 3270 // Linux mmap allows caller to pass an address as hint; give it a try first, 3271 // if kernel honors the hint then we can return immediately. 3272 char * addr = anon_mmap(requested_addr, bytes, false); 3273 if (addr == requested_addr) { 3274 return requested_addr; 3275 } 3276 3277 if (addr != NULL) { 3278 // mmap() is successful but it fails to reserve at the requested address 3279 anon_munmap(addr, bytes); 3280 } 3281 3282 int i; 3283 for (i = 0; i < max_tries; ++i) { 3284 base[i] = reserve_memory(bytes); 3285 3286 if (base[i] != NULL) { 3287 // Is this the block we wanted? 3288 if (base[i] == requested_addr) { 3289 size[i] = bytes; 3290 break; 3291 } 3292 3293 // Does this overlap the block we wanted? Give back the overlapped 3294 // parts and try again. 3295 3296 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3297 if (top_overlap >= 0 && top_overlap < bytes) { 3298 unmap_memory(base[i], top_overlap); 3299 base[i] += top_overlap; 3300 size[i] = bytes - top_overlap; 3301 } else { 3302 size_t bottom_overlap = base[i] + bytes - requested_addr; 3303 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3304 unmap_memory(requested_addr, bottom_overlap); 3305 size[i] = bytes - bottom_overlap; 3306 } else { 3307 size[i] = bytes; 3308 } 3309 } 3310 } 3311 } 3312 3313 // Give back the unused reserved pieces. 3314 3315 for (int j = 0; j < i; ++j) { 3316 if (base[j] != NULL) { 3317 unmap_memory(base[j], size[j]); 3318 } 3319 } 3320 3321 if (i < max_tries) { 3322 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3323 return requested_addr; 3324 } else { 3325 _highest_vm_reserved_address = old_highest; 3326 return NULL; 3327 } 3328} 3329 3330size_t os::read(int fd, void *buf, unsigned int nBytes) { 3331 return ::read(fd, buf, nBytes); 3332} 3333 3334// TODO-FIXME: reconcile Solaris' os::sleep with the linux variation. 3335// Solaris uses poll(), linux uses park(). 3336// Poll() is likely a better choice, assuming that Thread.interrupt() 3337// generates a SIGUSRx signal. Note that SIGUSR1 can interfere with 3338// SIGSEGV, see 4355769. 3339 3340int os::sleep(Thread* thread, jlong millis, bool interruptible) { 3341 assert(thread == Thread::current(), "thread consistency check"); 3342 3343 ParkEvent * const slp = thread->_SleepEvent ; 3344 slp->reset() ; 3345 OrderAccess::fence() ; 3346 3347 if (interruptible) { 3348 jlong prevtime = javaTimeNanos(); 3349 3350 for (;;) { 3351 if (os::is_interrupted(thread, true)) { 3352 return OS_INTRPT; 3353 } 3354 3355 jlong newtime = javaTimeNanos(); 3356 3357 if (newtime - prevtime < 0) { 3358 // time moving backwards, should only happen if no monotonic clock 3359 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3360 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3361 } else { 3362 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3363 } 3364 3365 if(millis <= 0) { 3366 return OS_OK; 3367 } 3368 3369 prevtime = newtime; 3370 3371 { 3372 assert(thread->is_Java_thread(), "sanity check"); 3373 JavaThread *jt = (JavaThread *) thread; 3374 ThreadBlockInVM tbivm(jt); 3375 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */); 3376 3377 jt->set_suspend_equivalent(); 3378 // cleared by handle_special_suspend_equivalent_condition() or 3379 // java_suspend_self() via check_and_wait_while_suspended() 3380 3381 slp->park(millis); 3382 3383 // were we externally suspended while we were waiting? 3384 jt->check_and_wait_while_suspended(); 3385 } 3386 } 3387 } else { 3388 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 3389 jlong prevtime = javaTimeNanos(); 3390 3391 for (;;) { 3392 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on 3393 // the 1st iteration ... 3394 jlong newtime = javaTimeNanos(); 3395 3396 if (newtime - prevtime < 0) { 3397 // time moving backwards, should only happen if no monotonic clock 3398 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3399 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3400 } else { 3401 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3402 } 3403 3404 if(millis <= 0) break ; 3405 3406 prevtime = newtime; 3407 slp->park(millis); 3408 } 3409 return OS_OK ; 3410 } 3411} 3412 3413int os::naked_sleep() { 3414 // %% make the sleep time an integer flag. for now use 1 millisec. 3415 return os::sleep(Thread::current(), 1, false); 3416} 3417 3418// Sleep forever; naked call to OS-specific sleep; use with CAUTION 3419void os::infinite_sleep() { 3420 while (true) { // sleep forever ... 3421 ::sleep(100); // ... 100 seconds at a time 3422 } 3423} 3424 3425// Used to convert frequent JVM_Yield() to nops 3426bool os::dont_yield() { 3427 return DontYieldALot; 3428} 3429 3430void os::yield() { 3431 sched_yield(); 3432} 3433 3434os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 3435 3436void os::yield_all(int attempts) { 3437 // Yields to all threads, including threads with lower priorities 3438 // Threads on Linux are all with same priority. The Solaris style 3439 // os::yield_all() with nanosleep(1ms) is not necessary. 3440 sched_yield(); 3441} 3442 3443// Called from the tight loops to possibly influence time-sharing heuristics 3444void os::loop_breaker(int attempts) { 3445 os::yield_all(attempts); 3446} 3447 3448//////////////////////////////////////////////////////////////////////////////// 3449// thread priority support 3450 3451// Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3452// only supports dynamic priority, static priority must be zero. For real-time 3453// applications, Linux supports SCHED_RR which allows static priority (1-99). 3454// However, for large multi-threaded applications, SCHED_RR is not only slower 3455// than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3456// of 5 runs - Sep 2005). 3457// 3458// The following code actually changes the niceness of kernel-thread/LWP. It 3459// has an assumption that setpriority() only modifies one kernel-thread/LWP, 3460// not the entire user process, and user level threads are 1:1 mapped to kernel 3461// threads. It has always been the case, but could change in the future. For 3462// this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3463// It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3464 3465int os::java_to_os_priority[CriticalPriority + 1] = { 3466 19, // 0 Entry should never be used 3467 3468 4, // 1 MinPriority 3469 3, // 2 3470 2, // 3 3471 3472 1, // 4 3473 0, // 5 NormPriority 3474 -1, // 6 3475 3476 -2, // 7 3477 -3, // 8 3478 -4, // 9 NearMaxPriority 3479 3480 -5, // 10 MaxPriority 3481 3482 -5 // 11 CriticalPriority 3483}; 3484 3485static int prio_init() { 3486 if (ThreadPriorityPolicy == 1) { 3487 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3488 // if effective uid is not root. Perhaps, a more elegant way of doing 3489 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3490 if (geteuid() != 0) { 3491 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3492 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3493 } 3494 ThreadPriorityPolicy = 0; 3495 } 3496 } 3497 if (UseCriticalJavaThreadPriority) { 3498 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3499 } 3500 return 0; 3501} 3502 3503OSReturn os::set_native_priority(Thread* thread, int newpri) { 3504 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 3505 3506 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3507 return (ret == 0) ? OS_OK : OS_ERR; 3508} 3509 3510OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3511 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3512 *priority_ptr = java_to_os_priority[NormPriority]; 3513 return OS_OK; 3514 } 3515 3516 errno = 0; 3517 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3518 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3519} 3520 3521// Hint to the underlying OS that a task switch would not be good. 3522// Void return because it's a hint and can fail. 3523void os::hint_no_preempt() {} 3524 3525//////////////////////////////////////////////////////////////////////////////// 3526// suspend/resume support 3527 3528// the low-level signal-based suspend/resume support is a remnant from the 3529// old VM-suspension that used to be for java-suspension, safepoints etc, 3530// within hotspot. Now there is a single use-case for this: 3531// - calling get_thread_pc() on the VMThread by the flat-profiler task 3532// that runs in the watcher thread. 3533// The remaining code is greatly simplified from the more general suspension 3534// code that used to be used. 3535// 3536// The protocol is quite simple: 3537// - suspend: 3538// - sends a signal to the target thread 3539// - polls the suspend state of the osthread using a yield loop 3540// - target thread signal handler (SR_handler) sets suspend state 3541// and blocks in sigsuspend until continued 3542// - resume: 3543// - sets target osthread state to continue 3544// - sends signal to end the sigsuspend loop in the SR_handler 3545// 3546// Note that the SR_lock plays no role in this suspend/resume protocol. 3547// 3548 3549static void resume_clear_context(OSThread *osthread) { 3550 osthread->set_ucontext(NULL); 3551 osthread->set_siginfo(NULL); 3552 3553 // notify the suspend action is completed, we have now resumed 3554 osthread->sr.clear_suspended(); 3555} 3556 3557static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 3558 osthread->set_ucontext(context); 3559 osthread->set_siginfo(siginfo); 3560} 3561 3562// 3563// Handler function invoked when a thread's execution is suspended or 3564// resumed. We have to be careful that only async-safe functions are 3565// called here (Note: most pthread functions are not async safe and 3566// should be avoided.) 3567// 3568// Note: sigwait() is a more natural fit than sigsuspend() from an 3569// interface point of view, but sigwait() prevents the signal hander 3570// from being run. libpthread would get very confused by not having 3571// its signal handlers run and prevents sigwait()'s use with the 3572// mutex granting granting signal. 3573// 3574// Currently only ever called on the VMThread 3575// 3576static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3577 // Save and restore errno to avoid confusing native code with EINTR 3578 // after sigsuspend. 3579 int old_errno = errno; 3580 3581 Thread* thread = Thread::current(); 3582 OSThread* osthread = thread->osthread(); 3583 assert(thread->is_VM_thread(), "Must be VMThread"); 3584 // read current suspend action 3585 int action = osthread->sr.suspend_action(); 3586 if (action == os::Linux::SuspendResume::SR_SUSPEND) { 3587 suspend_save_context(osthread, siginfo, context); 3588 3589 // Notify the suspend action is about to be completed. do_suspend() 3590 // waits until SR_SUSPENDED is set and then returns. We will wait 3591 // here for a resume signal and that completes the suspend-other 3592 // action. do_suspend/do_resume is always called as a pair from 3593 // the same thread - so there are no races 3594 3595 // notify the caller 3596 osthread->sr.set_suspended(); 3597 3598 sigset_t suspend_set; // signals for sigsuspend() 3599 3600 // get current set of blocked signals and unblock resume signal 3601 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3602 sigdelset(&suspend_set, SR_signum); 3603 3604 // wait here until we are resumed 3605 do { 3606 sigsuspend(&suspend_set); 3607 // ignore all returns until we get a resume signal 3608 } while (osthread->sr.suspend_action() != os::Linux::SuspendResume::SR_CONTINUE); 3609 3610 resume_clear_context(osthread); 3611 3612 } else { 3613 assert(action == os::Linux::SuspendResume::SR_CONTINUE, "unexpected sr action"); 3614 // nothing special to do - just leave the handler 3615 } 3616 3617 errno = old_errno; 3618} 3619 3620 3621static int SR_initialize() { 3622 struct sigaction act; 3623 char *s; 3624 /* Get signal number to use for suspend/resume */ 3625 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 3626 int sig = ::strtol(s, 0, 10); 3627 if (sig > 0 || sig < _NSIG) { 3628 SR_signum = sig; 3629 } 3630 } 3631 3632 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 3633 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 3634 3635 sigemptyset(&SR_sigset); 3636 sigaddset(&SR_sigset, SR_signum); 3637 3638 /* Set up signal handler for suspend/resume */ 3639 act.sa_flags = SA_RESTART|SA_SIGINFO; 3640 act.sa_handler = (void (*)(int)) SR_handler; 3641 3642 // SR_signum is blocked by default. 3643 // 4528190 - We also need to block pthread restart signal (32 on all 3644 // supported Linux platforms). Note that LinuxThreads need to block 3645 // this signal for all threads to work properly. So we don't have 3646 // to use hard-coded signal number when setting up the mask. 3647 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 3648 3649 if (sigaction(SR_signum, &act, 0) == -1) { 3650 return -1; 3651 } 3652 3653 // Save signal flag 3654 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 3655 return 0; 3656} 3657 3658static int SR_finalize() { 3659 return 0; 3660} 3661 3662 3663// returns true on success and false on error - really an error is fatal 3664// but this seems the normal response to library errors 3665static bool do_suspend(OSThread* osthread) { 3666 // mark as suspended and send signal 3667 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_SUSPEND); 3668 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3669 assert_status(status == 0, status, "pthread_kill"); 3670 3671 // check status and wait until notified of suspension 3672 if (status == 0) { 3673 for (int i = 0; !osthread->sr.is_suspended(); i++) { 3674 os::yield_all(i); 3675 } 3676 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_NONE); 3677 return true; 3678 } 3679 else { 3680 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_NONE); 3681 return false; 3682 } 3683} 3684 3685static void do_resume(OSThread* osthread) { 3686 assert(osthread->sr.is_suspended(), "thread should be suspended"); 3687 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_CONTINUE); 3688 3689 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3690 assert_status(status == 0, status, "pthread_kill"); 3691 // check status and wait unit notified of resumption 3692 if (status == 0) { 3693 for (int i = 0; osthread->sr.is_suspended(); i++) { 3694 os::yield_all(i); 3695 } 3696 } 3697 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_NONE); 3698} 3699 3700//////////////////////////////////////////////////////////////////////////////// 3701// interrupt support 3702 3703void os::interrupt(Thread* thread) { 3704 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3705 "possibility of dangling Thread pointer"); 3706 3707 OSThread* osthread = thread->osthread(); 3708 3709 if (!osthread->interrupted()) { 3710 osthread->set_interrupted(true); 3711 // More than one thread can get here with the same value of osthread, 3712 // resulting in multiple notifications. We do, however, want the store 3713 // to interrupted() to be visible to other threads before we execute unpark(). 3714 OrderAccess::fence(); 3715 ParkEvent * const slp = thread->_SleepEvent ; 3716 if (slp != NULL) slp->unpark() ; 3717 } 3718 3719 // For JSR166. Unpark even if interrupt status already was set 3720 if (thread->is_Java_thread()) 3721 ((JavaThread*)thread)->parker()->unpark(); 3722 3723 ParkEvent * ev = thread->_ParkEvent ; 3724 if (ev != NULL) ev->unpark() ; 3725 3726} 3727 3728bool os::is_interrupted(Thread* thread, bool clear_interrupted) { 3729 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3730 "possibility of dangling Thread pointer"); 3731 3732 OSThread* osthread = thread->osthread(); 3733 3734 bool interrupted = osthread->interrupted(); 3735 3736 if (interrupted && clear_interrupted) { 3737 osthread->set_interrupted(false); 3738 // consider thread->_SleepEvent->reset() ... optional optimization 3739 } 3740 3741 return interrupted; 3742} 3743 3744/////////////////////////////////////////////////////////////////////////////////// 3745// signal handling (except suspend/resume) 3746 3747// This routine may be used by user applications as a "hook" to catch signals. 3748// The user-defined signal handler must pass unrecognized signals to this 3749// routine, and if it returns true (non-zero), then the signal handler must 3750// return immediately. If the flag "abort_if_unrecognized" is true, then this 3751// routine will never retun false (zero), but instead will execute a VM panic 3752// routine kill the process. 3753// 3754// If this routine returns false, it is OK to call it again. This allows 3755// the user-defined signal handler to perform checks either before or after 3756// the VM performs its own checks. Naturally, the user code would be making 3757// a serious error if it tried to handle an exception (such as a null check 3758// or breakpoint) that the VM was generating for its own correct operation. 3759// 3760// This routine may recognize any of the following kinds of signals: 3761// SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 3762// It should be consulted by handlers for any of those signals. 3763// 3764// The caller of this routine must pass in the three arguments supplied 3765// to the function referred to in the "sa_sigaction" (not the "sa_handler") 3766// field of the structure passed to sigaction(). This routine assumes that 3767// the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 3768// 3769// Note that the VM will print warnings if it detects conflicting signal 3770// handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 3771// 3772extern "C" JNIEXPORT int 3773JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 3774 void* ucontext, int abort_if_unrecognized); 3775 3776void signalHandler(int sig, siginfo_t* info, void* uc) { 3777 assert(info != NULL && uc != NULL, "it must be old kernel"); 3778 int orig_errno = errno; // Preserve errno value over signal handler. 3779 JVM_handle_linux_signal(sig, info, uc, true); 3780 errno = orig_errno; 3781} 3782 3783 3784// This boolean allows users to forward their own non-matching signals 3785// to JVM_handle_linux_signal, harmlessly. 3786bool os::Linux::signal_handlers_are_installed = false; 3787 3788// For signal-chaining 3789struct sigaction os::Linux::sigact[MAXSIGNUM]; 3790unsigned int os::Linux::sigs = 0; 3791bool os::Linux::libjsig_is_loaded = false; 3792typedef struct sigaction *(*get_signal_t)(int); 3793get_signal_t os::Linux::get_signal_action = NULL; 3794 3795struct sigaction* os::Linux::get_chained_signal_action(int sig) { 3796 struct sigaction *actp = NULL; 3797 3798 if (libjsig_is_loaded) { 3799 // Retrieve the old signal handler from libjsig 3800 actp = (*get_signal_action)(sig); 3801 } 3802 if (actp == NULL) { 3803 // Retrieve the preinstalled signal handler from jvm 3804 actp = get_preinstalled_handler(sig); 3805 } 3806 3807 return actp; 3808} 3809 3810static bool call_chained_handler(struct sigaction *actp, int sig, 3811 siginfo_t *siginfo, void *context) { 3812 // Call the old signal handler 3813 if (actp->sa_handler == SIG_DFL) { 3814 // It's more reasonable to let jvm treat it as an unexpected exception 3815 // instead of taking the default action. 3816 return false; 3817 } else if (actp->sa_handler != SIG_IGN) { 3818 if ((actp->sa_flags & SA_NODEFER) == 0) { 3819 // automaticlly block the signal 3820 sigaddset(&(actp->sa_mask), sig); 3821 } 3822 3823 sa_handler_t hand; 3824 sa_sigaction_t sa; 3825 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 3826 // retrieve the chained handler 3827 if (siginfo_flag_set) { 3828 sa = actp->sa_sigaction; 3829 } else { 3830 hand = actp->sa_handler; 3831 } 3832 3833 if ((actp->sa_flags & SA_RESETHAND) != 0) { 3834 actp->sa_handler = SIG_DFL; 3835 } 3836 3837 // try to honor the signal mask 3838 sigset_t oset; 3839 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 3840 3841 // call into the chained handler 3842 if (siginfo_flag_set) { 3843 (*sa)(sig, siginfo, context); 3844 } else { 3845 (*hand)(sig); 3846 } 3847 3848 // restore the signal mask 3849 pthread_sigmask(SIG_SETMASK, &oset, 0); 3850 } 3851 // Tell jvm's signal handler the signal is taken care of. 3852 return true; 3853} 3854 3855bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 3856 bool chained = false; 3857 // signal-chaining 3858 if (UseSignalChaining) { 3859 struct sigaction *actp = get_chained_signal_action(sig); 3860 if (actp != NULL) { 3861 chained = call_chained_handler(actp, sig, siginfo, context); 3862 } 3863 } 3864 return chained; 3865} 3866 3867struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 3868 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 3869 return &sigact[sig]; 3870 } 3871 return NULL; 3872} 3873 3874void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 3875 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3876 sigact[sig] = oldAct; 3877 sigs |= (unsigned int)1 << sig; 3878} 3879 3880// for diagnostic 3881int os::Linux::sigflags[MAXSIGNUM]; 3882 3883int os::Linux::get_our_sigflags(int sig) { 3884 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3885 return sigflags[sig]; 3886} 3887 3888void os::Linux::set_our_sigflags(int sig, int flags) { 3889 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3890 sigflags[sig] = flags; 3891} 3892 3893void os::Linux::set_signal_handler(int sig, bool set_installed) { 3894 // Check for overwrite. 3895 struct sigaction oldAct; 3896 sigaction(sig, (struct sigaction*)NULL, &oldAct); 3897 3898 void* oldhand = oldAct.sa_sigaction 3899 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3900 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3901 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 3902 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 3903 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 3904 if (AllowUserSignalHandlers || !set_installed) { 3905 // Do not overwrite; user takes responsibility to forward to us. 3906 return; 3907 } else if (UseSignalChaining) { 3908 // save the old handler in jvm 3909 save_preinstalled_handler(sig, oldAct); 3910 // libjsig also interposes the sigaction() call below and saves the 3911 // old sigaction on it own. 3912 } else { 3913 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 3914 "%#lx for signal %d.", (long)oldhand, sig)); 3915 } 3916 } 3917 3918 struct sigaction sigAct; 3919 sigfillset(&(sigAct.sa_mask)); 3920 sigAct.sa_handler = SIG_DFL; 3921 if (!set_installed) { 3922 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3923 } else { 3924 sigAct.sa_sigaction = signalHandler; 3925 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3926 } 3927 // Save flags, which are set by ours 3928 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3929 sigflags[sig] = sigAct.sa_flags; 3930 3931 int ret = sigaction(sig, &sigAct, &oldAct); 3932 assert(ret == 0, "check"); 3933 3934 void* oldhand2 = oldAct.sa_sigaction 3935 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3936 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3937 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 3938} 3939 3940// install signal handlers for signals that HotSpot needs to 3941// handle in order to support Java-level exception handling. 3942 3943void os::Linux::install_signal_handlers() { 3944 if (!signal_handlers_are_installed) { 3945 signal_handlers_are_installed = true; 3946 3947 // signal-chaining 3948 typedef void (*signal_setting_t)(); 3949 signal_setting_t begin_signal_setting = NULL; 3950 signal_setting_t end_signal_setting = NULL; 3951 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3952 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 3953 if (begin_signal_setting != NULL) { 3954 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3955 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 3956 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 3957 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 3958 libjsig_is_loaded = true; 3959 assert(UseSignalChaining, "should enable signal-chaining"); 3960 } 3961 if (libjsig_is_loaded) { 3962 // Tell libjsig jvm is setting signal handlers 3963 (*begin_signal_setting)(); 3964 } 3965 3966 set_signal_handler(SIGSEGV, true); 3967 set_signal_handler(SIGPIPE, true); 3968 set_signal_handler(SIGBUS, true); 3969 set_signal_handler(SIGILL, true); 3970 set_signal_handler(SIGFPE, true); 3971 set_signal_handler(SIGXFSZ, true); 3972 3973 if (libjsig_is_loaded) { 3974 // Tell libjsig jvm finishes setting signal handlers 3975 (*end_signal_setting)(); 3976 } 3977 3978 // We don't activate signal checker if libjsig is in place, we trust ourselves 3979 // and if UserSignalHandler is installed all bets are off. 3980 // Log that signal checking is off only if -verbose:jni is specified. 3981 if (CheckJNICalls) { 3982 if (libjsig_is_loaded) { 3983 if (PrintJNIResolving) { 3984 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 3985 } 3986 check_signals = false; 3987 } 3988 if (AllowUserSignalHandlers) { 3989 if (PrintJNIResolving) { 3990 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 3991 } 3992 check_signals = false; 3993 } 3994 } 3995 } 3996} 3997 3998// This is the fastest way to get thread cpu time on Linux. 3999// Returns cpu time (user+sys) for any thread, not only for current. 4000// POSIX compliant clocks are implemented in the kernels 2.6.16+. 4001// It might work on 2.6.10+ with a special kernel/glibc patch. 4002// For reference, please, see IEEE Std 1003.1-2004: 4003// http://www.unix.org/single_unix_specification 4004 4005jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4006 struct timespec tp; 4007 int rc = os::Linux::clock_gettime(clockid, &tp); 4008 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4009 4010 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4011} 4012 4013///// 4014// glibc on Linux platform uses non-documented flag 4015// to indicate, that some special sort of signal 4016// trampoline is used. 4017// We will never set this flag, and we should 4018// ignore this flag in our diagnostic 4019#ifdef SIGNIFICANT_SIGNAL_MASK 4020#undef SIGNIFICANT_SIGNAL_MASK 4021#endif 4022#define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4023 4024static const char* get_signal_handler_name(address handler, 4025 char* buf, int buflen) { 4026 int offset; 4027 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4028 if (found) { 4029 // skip directory names 4030 const char *p1, *p2; 4031 p1 = buf; 4032 size_t len = strlen(os::file_separator()); 4033 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4034 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4035 } else { 4036 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4037 } 4038 return buf; 4039} 4040 4041static void print_signal_handler(outputStream* st, int sig, 4042 char* buf, size_t buflen) { 4043 struct sigaction sa; 4044 4045 sigaction(sig, NULL, &sa); 4046 4047 // See comment for SIGNIFICANT_SIGNAL_MASK define 4048 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4049 4050 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4051 4052 address handler = (sa.sa_flags & SA_SIGINFO) 4053 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4054 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4055 4056 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4057 st->print("SIG_DFL"); 4058 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4059 st->print("SIG_IGN"); 4060 } else { 4061 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4062 } 4063 4064 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask); 4065 4066 address rh = VMError::get_resetted_sighandler(sig); 4067 // May be, handler was resetted by VMError? 4068 if(rh != NULL) { 4069 handler = rh; 4070 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4071 } 4072 4073 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags); 4074 4075 // Check: is it our handler? 4076 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4077 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4078 // It is our signal handler 4079 // check for flags, reset system-used one! 4080 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4081 st->print( 4082 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4083 os::Linux::get_our_sigflags(sig)); 4084 } 4085 } 4086 st->cr(); 4087} 4088 4089 4090#define DO_SIGNAL_CHECK(sig) \ 4091 if (!sigismember(&check_signal_done, sig)) \ 4092 os::Linux::check_signal_handler(sig) 4093 4094// This method is a periodic task to check for misbehaving JNI applications 4095// under CheckJNI, we can add any periodic checks here 4096 4097void os::run_periodic_checks() { 4098 4099 if (check_signals == false) return; 4100 4101 // SEGV and BUS if overridden could potentially prevent 4102 // generation of hs*.log in the event of a crash, debugging 4103 // such a case can be very challenging, so we absolutely 4104 // check the following for a good measure: 4105 DO_SIGNAL_CHECK(SIGSEGV); 4106 DO_SIGNAL_CHECK(SIGILL); 4107 DO_SIGNAL_CHECK(SIGFPE); 4108 DO_SIGNAL_CHECK(SIGBUS); 4109 DO_SIGNAL_CHECK(SIGPIPE); 4110 DO_SIGNAL_CHECK(SIGXFSZ); 4111 4112 4113 // ReduceSignalUsage allows the user to override these handlers 4114 // see comments at the very top and jvm_solaris.h 4115 if (!ReduceSignalUsage) { 4116 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4117 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4118 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4119 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4120 } 4121 4122 DO_SIGNAL_CHECK(SR_signum); 4123 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4124} 4125 4126typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4127 4128static os_sigaction_t os_sigaction = NULL; 4129 4130void os::Linux::check_signal_handler(int sig) { 4131 char buf[O_BUFLEN]; 4132 address jvmHandler = NULL; 4133 4134 4135 struct sigaction act; 4136 if (os_sigaction == NULL) { 4137 // only trust the default sigaction, in case it has been interposed 4138 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4139 if (os_sigaction == NULL) return; 4140 } 4141 4142 os_sigaction(sig, (struct sigaction*)NULL, &act); 4143 4144 4145 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4146 4147 address thisHandler = (act.sa_flags & SA_SIGINFO) 4148 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4149 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 4150 4151 4152 switch(sig) { 4153 case SIGSEGV: 4154 case SIGBUS: 4155 case SIGFPE: 4156 case SIGPIPE: 4157 case SIGILL: 4158 case SIGXFSZ: 4159 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4160 break; 4161 4162 case SHUTDOWN1_SIGNAL: 4163 case SHUTDOWN2_SIGNAL: 4164 case SHUTDOWN3_SIGNAL: 4165 case BREAK_SIGNAL: 4166 jvmHandler = (address)user_handler(); 4167 break; 4168 4169 case INTERRUPT_SIGNAL: 4170 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4171 break; 4172 4173 default: 4174 if (sig == SR_signum) { 4175 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4176 } else { 4177 return; 4178 } 4179 break; 4180 } 4181 4182 if (thisHandler != jvmHandler) { 4183 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4184 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4185 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4186 // No need to check this sig any longer 4187 sigaddset(&check_signal_done, sig); 4188 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4189 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4190 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4191 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4192 // No need to check this sig any longer 4193 sigaddset(&check_signal_done, sig); 4194 } 4195 4196 // Dump all the signal 4197 if (sigismember(&check_signal_done, sig)) { 4198 print_signal_handlers(tty, buf, O_BUFLEN); 4199 } 4200} 4201 4202extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 4203 4204extern bool signal_name(int signo, char* buf, size_t len); 4205 4206const char* os::exception_name(int exception_code, char* buf, size_t size) { 4207 if (0 < exception_code && exception_code <= SIGRTMAX) { 4208 // signal 4209 if (!signal_name(exception_code, buf, size)) { 4210 jio_snprintf(buf, size, "SIG%d", exception_code); 4211 } 4212 return buf; 4213 } else { 4214 return NULL; 4215 } 4216} 4217 4218// this is called _before_ the most of global arguments have been parsed 4219void os::init(void) { 4220 char dummy; /* used to get a guess on initial stack address */ 4221// first_hrtime = gethrtime(); 4222 4223 // With LinuxThreads the JavaMain thread pid (primordial thread) 4224 // is different than the pid of the java launcher thread. 4225 // So, on Linux, the launcher thread pid is passed to the VM 4226 // via the sun.java.launcher.pid property. 4227 // Use this property instead of getpid() if it was correctly passed. 4228 // See bug 6351349. 4229 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4230 4231 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4232 4233 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4234 4235 init_random(1234567); 4236 4237 ThreadCritical::initialize(); 4238 4239 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4240 if (Linux::page_size() == -1) { 4241 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4242 strerror(errno))); 4243 } 4244 init_page_sizes((size_t) Linux::page_size()); 4245 4246 Linux::initialize_system_info(); 4247 4248 // main_thread points to the aboriginal thread 4249 Linux::_main_thread = pthread_self(); 4250 4251 Linux::clock_init(); 4252 initial_time_count = os::elapsed_counter(); 4253 pthread_mutex_init(&dl_mutex, NULL); 4254} 4255 4256// To install functions for atexit system call 4257extern "C" { 4258 static void perfMemory_exit_helper() { 4259 perfMemory_exit(); 4260 } 4261} 4262 4263// this is called _after_ the global arguments have been parsed 4264jint os::init_2(void) 4265{ 4266 Linux::fast_thread_clock_init(); 4267 4268 // Allocate a single page and mark it as readable for safepoint polling 4269 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4270 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 4271 4272 os::set_polling_page( polling_page ); 4273 4274#ifndef PRODUCT 4275 if(Verbose && PrintMiscellaneous) 4276 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 4277#endif 4278 4279 if (!UseMembar) { 4280 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4281 guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page"); 4282 os::set_memory_serialize_page( mem_serialize_page ); 4283 4284#ifndef PRODUCT 4285 if(Verbose && PrintMiscellaneous) 4286 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 4287#endif 4288 } 4289 4290 os::large_page_init(); 4291 4292 // initialize suspend/resume support - must do this before signal_sets_init() 4293 if (SR_initialize() != 0) { 4294 perror("SR_initialize failed"); 4295 return JNI_ERR; 4296 } 4297 4298 Linux::signal_sets_init(); 4299 Linux::install_signal_handlers(); 4300 4301 // Check minimum allowable stack size for thread creation and to initialize 4302 // the java system classes, including StackOverflowError - depends on page 4303 // size. Add a page for compiler2 recursion in main thread. 4304 // Add in 2*BytesPerWord times page size to account for VM stack during 4305 // class initialization depending on 32 or 64 bit VM. 4306 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4307 (size_t)(StackYellowPages+StackRedPages+StackShadowPages+ 4308 2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::page_size()); 4309 4310 size_t threadStackSizeInBytes = ThreadStackSize * K; 4311 if (threadStackSizeInBytes != 0 && 4312 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4313 tty->print_cr("\nThe stack size specified is too small, " 4314 "Specify at least %dk", 4315 os::Linux::min_stack_allowed/ K); 4316 return JNI_ERR; 4317 } 4318 4319 // Make the stack size a multiple of the page size so that 4320 // the yellow/red zones can be guarded. 4321 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4322 vm_page_size())); 4323 4324 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4325 4326 Linux::libpthread_init(); 4327 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4328 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4329 Linux::glibc_version(), Linux::libpthread_version(), 4330 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4331 } 4332 4333 if (UseNUMA) { 4334 if (!Linux::libnuma_init()) { 4335 UseNUMA = false; 4336 } else { 4337 if ((Linux::numa_max_node() < 1)) { 4338 // There's only one node(they start from 0), disable NUMA. 4339 UseNUMA = false; 4340 } 4341 } 4342 // With SHM large pages we cannot uncommit a page, so there's not way 4343 // we can make the adaptive lgrp chunk resizing work. If the user specified 4344 // both UseNUMA and UseLargePages (or UseSHM) on the command line - warn and 4345 // disable adaptive resizing. 4346 if (UseNUMA && UseLargePages && UseSHM) { 4347 if (!FLAG_IS_DEFAULT(UseNUMA)) { 4348 if (FLAG_IS_DEFAULT(UseLargePages) && FLAG_IS_DEFAULT(UseSHM)) { 4349 UseLargePages = false; 4350 } else { 4351 warning("UseNUMA is not fully compatible with SHM large pages, disabling adaptive resizing"); 4352 UseAdaptiveSizePolicy = false; 4353 UseAdaptiveNUMAChunkSizing = false; 4354 } 4355 } else { 4356 UseNUMA = false; 4357 } 4358 } 4359 if (!UseNUMA && ForceNUMA) { 4360 UseNUMA = true; 4361 } 4362 } 4363 4364 if (MaxFDLimit) { 4365 // set the number of file descriptors to max. print out error 4366 // if getrlimit/setrlimit fails but continue regardless. 4367 struct rlimit nbr_files; 4368 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4369 if (status != 0) { 4370 if (PrintMiscellaneous && (Verbose || WizardMode)) 4371 perror("os::init_2 getrlimit failed"); 4372 } else { 4373 nbr_files.rlim_cur = nbr_files.rlim_max; 4374 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4375 if (status != 0) { 4376 if (PrintMiscellaneous && (Verbose || WizardMode)) 4377 perror("os::init_2 setrlimit failed"); 4378 } 4379 } 4380 } 4381 4382 // Initialize lock used to serialize thread creation (see os::create_thread) 4383 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4384 4385 // at-exit methods are called in the reverse order of their registration. 4386 // atexit functions are called on return from main or as a result of a 4387 // call to exit(3C). There can be only 32 of these functions registered 4388 // and atexit() does not set errno. 4389 4390 if (PerfAllowAtExitRegistration) { 4391 // only register atexit functions if PerfAllowAtExitRegistration is set. 4392 // atexit functions can be delayed until process exit time, which 4393 // can be problematic for embedded VM situations. Embedded VMs should 4394 // call DestroyJavaVM() to assure that VM resources are released. 4395 4396 // note: perfMemory_exit_helper atexit function may be removed in 4397 // the future if the appropriate cleanup code can be added to the 4398 // VM_Exit VMOperation's doit method. 4399 if (atexit(perfMemory_exit_helper) != 0) { 4400 warning("os::init2 atexit(perfMemory_exit_helper) failed"); 4401 } 4402 } 4403 4404 // initialize thread priority policy 4405 prio_init(); 4406 4407 return JNI_OK; 4408} 4409 4410// this is called at the end of vm_initialization 4411void os::init_3(void) 4412{ 4413#ifdef JAVASE_EMBEDDED 4414 // Start the MemNotifyThread 4415 if (LowMemoryProtection) { 4416 MemNotifyThread::start(); 4417 } 4418 return; 4419#endif 4420} 4421 4422// Mark the polling page as unreadable 4423void os::make_polling_page_unreadable(void) { 4424 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 4425 fatal("Could not disable polling page"); 4426}; 4427 4428// Mark the polling page as readable 4429void os::make_polling_page_readable(void) { 4430 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4431 fatal("Could not enable polling page"); 4432 } 4433}; 4434 4435int os::active_processor_count() { 4436 // Linux doesn't yet have a (official) notion of processor sets, 4437 // so just return the number of online processors. 4438 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4439 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4440 return online_cpus; 4441} 4442 4443void os::set_native_thread_name(const char *name) { 4444 // Not yet implemented. 4445 return; 4446} 4447 4448bool os::distribute_processes(uint length, uint* distribution) { 4449 // Not yet implemented. 4450 return false; 4451} 4452 4453bool os::bind_to_processor(uint processor_id) { 4454 // Not yet implemented. 4455 return false; 4456} 4457 4458/// 4459 4460// Suspends the target using the signal mechanism and then grabs the PC before 4461// resuming the target. Used by the flat-profiler only 4462ExtendedPC os::get_thread_pc(Thread* thread) { 4463 // Make sure that it is called by the watcher for the VMThread 4464 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4465 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4466 4467 ExtendedPC epc; 4468 4469 OSThread* osthread = thread->osthread(); 4470 if (do_suspend(osthread)) { 4471 if (osthread->ucontext() != NULL) { 4472 epc = os::Linux::ucontext_get_pc(osthread->ucontext()); 4473 } else { 4474 // NULL context is unexpected, double-check this is the VMThread 4475 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4476 } 4477 do_resume(osthread); 4478 } 4479 // failure means pthread_kill failed for some reason - arguably this is 4480 // a fatal problem, but such problems are ignored elsewhere 4481 4482 return epc; 4483} 4484 4485int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 4486{ 4487 if (is_NPTL()) { 4488 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4489 } else { 4490 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4491 // word back to default 64bit precision if condvar is signaled. Java 4492 // wants 53bit precision. Save and restore current value. 4493 int fpu = get_fpu_control_word(); 4494 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4495 set_fpu_control_word(fpu); 4496 return status; 4497 } 4498} 4499 4500//////////////////////////////////////////////////////////////////////////////// 4501// debug support 4502 4503static address same_page(address x, address y) { 4504 int page_bits = -os::vm_page_size(); 4505 if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits)) 4506 return x; 4507 else if (x > y) 4508 return (address)(intptr_t(y) | ~page_bits) + 1; 4509 else 4510 return (address)(intptr_t(y) & page_bits); 4511} 4512 4513bool os::find(address addr, outputStream* st) { 4514 Dl_info dlinfo; 4515 memset(&dlinfo, 0, sizeof(dlinfo)); 4516 if (dladdr(addr, &dlinfo)) { 4517 st->print(PTR_FORMAT ": ", addr); 4518 if (dlinfo.dli_sname != NULL) { 4519 st->print("%s+%#x", dlinfo.dli_sname, 4520 addr - (intptr_t)dlinfo.dli_saddr); 4521 } else if (dlinfo.dli_fname) { 4522 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4523 } else { 4524 st->print("<absolute address>"); 4525 } 4526 if (dlinfo.dli_fname) { 4527 st->print(" in %s", dlinfo.dli_fname); 4528 } 4529 if (dlinfo.dli_fbase) { 4530 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4531 } 4532 st->cr(); 4533 4534 if (Verbose) { 4535 // decode some bytes around the PC 4536 address begin = same_page(addr-40, addr); 4537 address end = same_page(addr+40, addr); 4538 address lowest = (address) dlinfo.dli_sname; 4539 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4540 if (begin < lowest) begin = lowest; 4541 Dl_info dlinfo2; 4542 if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr 4543 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 4544 end = (address) dlinfo2.dli_saddr; 4545 Disassembler::decode(begin, end, st); 4546 } 4547 return true; 4548 } 4549 return false; 4550} 4551 4552//////////////////////////////////////////////////////////////////////////////// 4553// misc 4554 4555// This does not do anything on Linux. This is basically a hook for being 4556// able to use structured exception handling (thread-local exception filters) 4557// on, e.g., Win32. 4558void 4559os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 4560 JavaCallArguments* args, Thread* thread) { 4561 f(value, method, args, thread); 4562} 4563 4564void os::print_statistics() { 4565} 4566 4567int os::message_box(const char* title, const char* message) { 4568 int i; 4569 fdStream err(defaultStream::error_fd()); 4570 for (i = 0; i < 78; i++) err.print_raw("="); 4571 err.cr(); 4572 err.print_raw_cr(title); 4573 for (i = 0; i < 78; i++) err.print_raw("-"); 4574 err.cr(); 4575 err.print_raw_cr(message); 4576 for (i = 0; i < 78; i++) err.print_raw("="); 4577 err.cr(); 4578 4579 char buf[16]; 4580 // Prevent process from exiting upon "read error" without consuming all CPU 4581 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 4582 4583 return buf[0] == 'y' || buf[0] == 'Y'; 4584} 4585 4586int os::stat(const char *path, struct stat *sbuf) { 4587 char pathbuf[MAX_PATH]; 4588 if (strlen(path) > MAX_PATH - 1) { 4589 errno = ENAMETOOLONG; 4590 return -1; 4591 } 4592 os::native_path(strcpy(pathbuf, path)); 4593 return ::stat(pathbuf, sbuf); 4594} 4595 4596bool os::check_heap(bool force) { 4597 return true; 4598} 4599 4600int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 4601 return ::vsnprintf(buf, count, format, args); 4602} 4603 4604// Is a (classpath) directory empty? 4605bool os::dir_is_empty(const char* path) { 4606 DIR *dir = NULL; 4607 struct dirent *ptr; 4608 4609 dir = opendir(path); 4610 if (dir == NULL) return true; 4611 4612 /* Scan the directory */ 4613 bool result = true; 4614 char buf[sizeof(struct dirent) + MAX_PATH]; 4615 while (result && (ptr = ::readdir(dir)) != NULL) { 4616 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 4617 result = false; 4618 } 4619 } 4620 closedir(dir); 4621 return result; 4622} 4623 4624// This code originates from JDK's sysOpen and open64_w 4625// from src/solaris/hpi/src/system_md.c 4626 4627#ifndef O_DELETE 4628#define O_DELETE 0x10000 4629#endif 4630 4631// Open a file. Unlink the file immediately after open returns 4632// if the specified oflag has the O_DELETE flag set. 4633// O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c 4634 4635int os::open(const char *path, int oflag, int mode) { 4636 4637 if (strlen(path) > MAX_PATH - 1) { 4638 errno = ENAMETOOLONG; 4639 return -1; 4640 } 4641 int fd; 4642 int o_delete = (oflag & O_DELETE); 4643 oflag = oflag & ~O_DELETE; 4644 4645 fd = ::open64(path, oflag, mode); 4646 if (fd == -1) return -1; 4647 4648 //If the open succeeded, the file might still be a directory 4649 { 4650 struct stat64 buf64; 4651 int ret = ::fstat64(fd, &buf64); 4652 int st_mode = buf64.st_mode; 4653 4654 if (ret != -1) { 4655 if ((st_mode & S_IFMT) == S_IFDIR) { 4656 errno = EISDIR; 4657 ::close(fd); 4658 return -1; 4659 } 4660 } else { 4661 ::close(fd); 4662 return -1; 4663 } 4664 } 4665 4666 /* 4667 * All file descriptors that are opened in the JVM and not 4668 * specifically destined for a subprocess should have the 4669 * close-on-exec flag set. If we don't set it, then careless 3rd 4670 * party native code might fork and exec without closing all 4671 * appropriate file descriptors (e.g. as we do in closeDescriptors in 4672 * UNIXProcess.c), and this in turn might: 4673 * 4674 * - cause end-of-file to fail to be detected on some file 4675 * descriptors, resulting in mysterious hangs, or 4676 * 4677 * - might cause an fopen in the subprocess to fail on a system 4678 * suffering from bug 1085341. 4679 * 4680 * (Yes, the default setting of the close-on-exec flag is a Unix 4681 * design flaw) 4682 * 4683 * See: 4684 * 1085341: 32-bit stdio routines should support file descriptors >255 4685 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed 4686 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 4687 */ 4688#ifdef FD_CLOEXEC 4689 { 4690 int flags = ::fcntl(fd, F_GETFD); 4691 if (flags != -1) 4692 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 4693 } 4694#endif 4695 4696 if (o_delete != 0) { 4697 ::unlink(path); 4698 } 4699 return fd; 4700} 4701 4702 4703// create binary file, rewriting existing file if required 4704int os::create_binary_file(const char* path, bool rewrite_existing) { 4705 int oflags = O_WRONLY | O_CREAT; 4706 if (!rewrite_existing) { 4707 oflags |= O_EXCL; 4708 } 4709 return ::open64(path, oflags, S_IREAD | S_IWRITE); 4710} 4711 4712// return current position of file pointer 4713jlong os::current_file_offset(int fd) { 4714 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 4715} 4716 4717// move file pointer to the specified offset 4718jlong os::seek_to_file_offset(int fd, jlong offset) { 4719 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 4720} 4721 4722// This code originates from JDK's sysAvailable 4723// from src/solaris/hpi/src/native_threads/src/sys_api_td.c 4724 4725int os::available(int fd, jlong *bytes) { 4726 jlong cur, end; 4727 int mode; 4728 struct stat64 buf64; 4729 4730 if (::fstat64(fd, &buf64) >= 0) { 4731 mode = buf64.st_mode; 4732 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 4733 /* 4734 * XXX: is the following call interruptible? If so, this might 4735 * need to go through the INTERRUPT_IO() wrapper as for other 4736 * blocking, interruptible calls in this file. 4737 */ 4738 int n; 4739 if (::ioctl(fd, FIONREAD, &n) >= 0) { 4740 *bytes = n; 4741 return 1; 4742 } 4743 } 4744 } 4745 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 4746 return 0; 4747 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 4748 return 0; 4749 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 4750 return 0; 4751 } 4752 *bytes = end - cur; 4753 return 1; 4754} 4755 4756int os::socket_available(int fd, jint *pbytes) { 4757 // Linux doc says EINTR not returned, unlike Solaris 4758 int ret = ::ioctl(fd, FIONREAD, pbytes); 4759 4760 //%% note ioctl can return 0 when successful, JVM_SocketAvailable 4761 // is expected to return 0 on failure and 1 on success to the jdk. 4762 return (ret < 0) ? 0 : 1; 4763} 4764 4765// Map a block of memory. 4766char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 4767 char *addr, size_t bytes, bool read_only, 4768 bool allow_exec) { 4769 int prot; 4770 int flags = MAP_PRIVATE; 4771 4772 if (read_only) { 4773 prot = PROT_READ; 4774 } else { 4775 prot = PROT_READ | PROT_WRITE; 4776 } 4777 4778 if (allow_exec) { 4779 prot |= PROT_EXEC; 4780 } 4781 4782 if (addr != NULL) { 4783 flags |= MAP_FIXED; 4784 } 4785 4786 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 4787 fd, file_offset); 4788 if (mapped_address == MAP_FAILED) { 4789 return NULL; 4790 } 4791 return mapped_address; 4792} 4793 4794 4795// Remap a block of memory. 4796char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 4797 char *addr, size_t bytes, bool read_only, 4798 bool allow_exec) { 4799 // same as map_memory() on this OS 4800 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 4801 allow_exec); 4802} 4803 4804 4805// Unmap a block of memory. 4806bool os::pd_unmap_memory(char* addr, size_t bytes) { 4807 return munmap(addr, bytes) == 0; 4808} 4809 4810static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 4811 4812static clockid_t thread_cpu_clockid(Thread* thread) { 4813 pthread_t tid = thread->osthread()->pthread_id(); 4814 clockid_t clockid; 4815 4816 // Get thread clockid 4817 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 4818 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 4819 return clockid; 4820} 4821 4822// current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 4823// are used by JVM M&M and JVMTI to get user+sys or user CPU time 4824// of a thread. 4825// 4826// current_thread_cpu_time() and thread_cpu_time(Thread*) returns 4827// the fast estimate available on the platform. 4828 4829jlong os::current_thread_cpu_time() { 4830 if (os::Linux::supports_fast_thread_cpu_time()) { 4831 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4832 } else { 4833 // return user + sys since the cost is the same 4834 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 4835 } 4836} 4837 4838jlong os::thread_cpu_time(Thread* thread) { 4839 // consistent with what current_thread_cpu_time() returns 4840 if (os::Linux::supports_fast_thread_cpu_time()) { 4841 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4842 } else { 4843 return slow_thread_cpu_time(thread, true /* user + sys */); 4844 } 4845} 4846 4847jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 4848 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4849 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4850 } else { 4851 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 4852 } 4853} 4854 4855jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4856 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4857 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4858 } else { 4859 return slow_thread_cpu_time(thread, user_sys_cpu_time); 4860 } 4861} 4862 4863// 4864// -1 on error. 4865// 4866 4867static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4868 static bool proc_task_unchecked = true; 4869 static const char *proc_stat_path = "/proc/%d/stat"; 4870 pid_t tid = thread->osthread()->thread_id(); 4871 char *s; 4872 char stat[2048]; 4873 int statlen; 4874 char proc_name[64]; 4875 int count; 4876 long sys_time, user_time; 4877 char cdummy; 4878 int idummy; 4879 long ldummy; 4880 FILE *fp; 4881 4882 // The /proc/<tid>/stat aggregates per-process usage on 4883 // new Linux kernels 2.6+ where NPTL is supported. 4884 // The /proc/self/task/<tid>/stat still has the per-thread usage. 4885 // See bug 6328462. 4886 // There possibly can be cases where there is no directory 4887 // /proc/self/task, so we check its availability. 4888 if (proc_task_unchecked && os::Linux::is_NPTL()) { 4889 // This is executed only once 4890 proc_task_unchecked = false; 4891 fp = fopen("/proc/self/task", "r"); 4892 if (fp != NULL) { 4893 proc_stat_path = "/proc/self/task/%d/stat"; 4894 fclose(fp); 4895 } 4896 } 4897 4898 sprintf(proc_name, proc_stat_path, tid); 4899 fp = fopen(proc_name, "r"); 4900 if ( fp == NULL ) return -1; 4901 statlen = fread(stat, 1, 2047, fp); 4902 stat[statlen] = '\0'; 4903 fclose(fp); 4904 4905 // Skip pid and the command string. Note that we could be dealing with 4906 // weird command names, e.g. user could decide to rename java launcher 4907 // to "java 1.4.2 :)", then the stat file would look like 4908 // 1234 (java 1.4.2 :)) R ... ... 4909 // We don't really need to know the command string, just find the last 4910 // occurrence of ")" and then start parsing from there. See bug 4726580. 4911 s = strrchr(stat, ')'); 4912 if (s == NULL ) return -1; 4913 4914 // Skip blank chars 4915 do s++; while (isspace(*s)); 4916 4917 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 4918 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 4919 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 4920 &user_time, &sys_time); 4921 if ( count != 13 ) return -1; 4922 if (user_sys_cpu_time) { 4923 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 4924 } else { 4925 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 4926 } 4927} 4928 4929void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4930 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4931 info_ptr->may_skip_backward = false; // elapsed time not wall time 4932 info_ptr->may_skip_forward = false; // elapsed time not wall time 4933 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4934} 4935 4936void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4937 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4938 info_ptr->may_skip_backward = false; // elapsed time not wall time 4939 info_ptr->may_skip_forward = false; // elapsed time not wall time 4940 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4941} 4942 4943bool os::is_thread_cpu_time_supported() { 4944 return true; 4945} 4946 4947// System loadavg support. Returns -1 if load average cannot be obtained. 4948// Linux doesn't yet have a (official) notion of processor sets, 4949// so just return the system wide load average. 4950int os::loadavg(double loadavg[], int nelem) { 4951 return ::getloadavg(loadavg, nelem); 4952} 4953 4954void os::pause() { 4955 char filename[MAX_PATH]; 4956 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 4957 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 4958 } else { 4959 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 4960 } 4961 4962 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 4963 if (fd != -1) { 4964 struct stat buf; 4965 ::close(fd); 4966 while (::stat(filename, &buf) == 0) { 4967 (void)::poll(NULL, 0, 100); 4968 } 4969 } else { 4970 jio_fprintf(stderr, 4971 "Could not open pause file '%s', continuing immediately.\n", filename); 4972 } 4973} 4974 4975 4976// Refer to the comments in os_solaris.cpp park-unpark. 4977// 4978// Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 4979// hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 4980// For specifics regarding the bug see GLIBC BUGID 261237 : 4981// http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 4982// Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 4983// will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 4984// is used. (The simple C test-case provided in the GLIBC bug report manifests the 4985// hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 4986// and monitorenter when we're using 1-0 locking. All those operations may result in 4987// calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 4988// of libpthread avoids the problem, but isn't practical. 4989// 4990// Possible remedies: 4991// 4992// 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 4993// This is palliative and probabilistic, however. If the thread is preempted 4994// between the call to compute_abstime() and pthread_cond_timedwait(), more 4995// than the minimum period may have passed, and the abstime may be stale (in the 4996// past) resultin in a hang. Using this technique reduces the odds of a hang 4997// but the JVM is still vulnerable, particularly on heavily loaded systems. 4998// 4999// 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5000// of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5001// NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5002// reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5003// thread. 5004// 5005// 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5006// that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5007// a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5008// This also works well. In fact it avoids kernel-level scalability impediments 5009// on certain platforms that don't handle lots of active pthread_cond_timedwait() 5010// timers in a graceful fashion. 5011// 5012// 4. When the abstime value is in the past it appears that control returns 5013// correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5014// Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5015// can avoid the problem by reinitializing the condvar -- by cond_destroy() 5016// followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5017// It may be possible to avoid reinitialization by checking the return 5018// value from pthread_cond_timedwait(). In addition to reinitializing the 5019// condvar we must establish the invariant that cond_signal() is only called 5020// within critical sections protected by the adjunct mutex. This prevents 5021// cond_signal() from "seeing" a condvar that's in the midst of being 5022// reinitialized or that is corrupt. Sadly, this invariant obviates the 5023// desirable signal-after-unlock optimization that avoids futile context switching. 5024// 5025// I'm also concerned that some versions of NTPL might allocate an auxilliary 5026// structure when a condvar is used or initialized. cond_destroy() would 5027// release the helper structure. Our reinitialize-after-timedwait fix 5028// put excessive stress on malloc/free and locks protecting the c-heap. 5029// 5030// We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5031// It may be possible to refine (4) by checking the kernel and NTPL verisons 5032// and only enabling the work-around for vulnerable environments. 5033 5034// utility to compute the abstime argument to timedwait: 5035// millis is the relative timeout time 5036// abstime will be the absolute timeout time 5037// TODO: replace compute_abstime() with unpackTime() 5038 5039static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5040 if (millis < 0) millis = 0; 5041 struct timeval now; 5042 int status = gettimeofday(&now, NULL); 5043 assert(status == 0, "gettimeofday"); 5044 jlong seconds = millis / 1000; 5045 millis %= 1000; 5046 if (seconds > 50000000) { // see man cond_timedwait(3T) 5047 seconds = 50000000; 5048 } 5049 abstime->tv_sec = now.tv_sec + seconds; 5050 long usec = now.tv_usec + millis * 1000; 5051 if (usec >= 1000000) { 5052 abstime->tv_sec += 1; 5053 usec -= 1000000; 5054 } 5055 abstime->tv_nsec = usec * 1000; 5056 return abstime; 5057} 5058 5059 5060// Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 5061// Conceptually TryPark() should be equivalent to park(0). 5062 5063int os::PlatformEvent::TryPark() { 5064 for (;;) { 5065 const int v = _Event ; 5066 guarantee ((v == 0) || (v == 1), "invariant") ; 5067 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 5068 } 5069} 5070 5071void os::PlatformEvent::park() { // AKA "down()" 5072 // Invariant: Only the thread associated with the Event/PlatformEvent 5073 // may call park(). 5074 // TODO: assert that _Assoc != NULL or _Assoc == Self 5075 int v ; 5076 for (;;) { 5077 v = _Event ; 5078 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5079 } 5080 guarantee (v >= 0, "invariant") ; 5081 if (v == 0) { 5082 // Do this the hard way by blocking ... 5083 int status = pthread_mutex_lock(_mutex); 5084 assert_status(status == 0, status, "mutex_lock"); 5085 guarantee (_nParked == 0, "invariant") ; 5086 ++ _nParked ; 5087 while (_Event < 0) { 5088 status = pthread_cond_wait(_cond, _mutex); 5089 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5090 // Treat this the same as if the wait was interrupted 5091 if (status == ETIME) { status = EINTR; } 5092 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5093 } 5094 -- _nParked ; 5095 5096 _Event = 0 ; 5097 status = pthread_mutex_unlock(_mutex); 5098 assert_status(status == 0, status, "mutex_unlock"); 5099 // Paranoia to ensure our locked and lock-free paths interact 5100 // correctly with each other. 5101 OrderAccess::fence(); 5102 } 5103 guarantee (_Event >= 0, "invariant") ; 5104} 5105 5106int os::PlatformEvent::park(jlong millis) { 5107 guarantee (_nParked == 0, "invariant") ; 5108 5109 int v ; 5110 for (;;) { 5111 v = _Event ; 5112 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5113 } 5114 guarantee (v >= 0, "invariant") ; 5115 if (v != 0) return OS_OK ; 5116 5117 // We do this the hard way, by blocking the thread. 5118 // Consider enforcing a minimum timeout value. 5119 struct timespec abst; 5120 compute_abstime(&abst, millis); 5121 5122 int ret = OS_TIMEOUT; 5123 int status = pthread_mutex_lock(_mutex); 5124 assert_status(status == 0, status, "mutex_lock"); 5125 guarantee (_nParked == 0, "invariant") ; 5126 ++_nParked ; 5127 5128 // Object.wait(timo) will return because of 5129 // (a) notification 5130 // (b) timeout 5131 // (c) thread.interrupt 5132 // 5133 // Thread.interrupt and object.notify{All} both call Event::set. 5134 // That is, we treat thread.interrupt as a special case of notification. 5135 // The underlying Solaris implementation, cond_timedwait, admits 5136 // spurious/premature wakeups, but the JLS/JVM spec prevents the 5137 // JVM from making those visible to Java code. As such, we must 5138 // filter out spurious wakeups. We assume all ETIME returns are valid. 5139 // 5140 // TODO: properly differentiate simultaneous notify+interrupt. 5141 // In that case, we should propagate the notify to another waiter. 5142 5143 while (_Event < 0) { 5144 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5145 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5146 pthread_cond_destroy (_cond); 5147 pthread_cond_init (_cond, NULL) ; 5148 } 5149 assert_status(status == 0 || status == EINTR || 5150 status == ETIME || status == ETIMEDOUT, 5151 status, "cond_timedwait"); 5152 if (!FilterSpuriousWakeups) break ; // previous semantics 5153 if (status == ETIME || status == ETIMEDOUT) break ; 5154 // We consume and ignore EINTR and spurious wakeups. 5155 } 5156 --_nParked ; 5157 if (_Event >= 0) { 5158 ret = OS_OK; 5159 } 5160 _Event = 0 ; 5161 status = pthread_mutex_unlock(_mutex); 5162 assert_status(status == 0, status, "mutex_unlock"); 5163 assert (_nParked == 0, "invariant") ; 5164 // Paranoia to ensure our locked and lock-free paths interact 5165 // correctly with each other. 5166 OrderAccess::fence(); 5167 return ret; 5168} 5169 5170void os::PlatformEvent::unpark() { 5171 // Transitions for _Event: 5172 // 0 :=> 1 5173 // 1 :=> 1 5174 // -1 :=> either 0 or 1; must signal target thread 5175 // That is, we can safely transition _Event from -1 to either 5176 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back 5177 // unpark() calls. 5178 // See also: "Semaphores in Plan 9" by Mullender & Cox 5179 // 5180 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5181 // that it will take two back-to-back park() calls for the owning 5182 // thread to block. This has the benefit of forcing a spurious return 5183 // from the first park() call after an unpark() call which will help 5184 // shake out uses of park() and unpark() without condition variables. 5185 5186 if (Atomic::xchg(1, &_Event) >= 0) return; 5187 5188 // Wait for the thread associated with the event to vacate 5189 int status = pthread_mutex_lock(_mutex); 5190 assert_status(status == 0, status, "mutex_lock"); 5191 int AnyWaiters = _nParked; 5192 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5193 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5194 AnyWaiters = 0; 5195 pthread_cond_signal(_cond); 5196 } 5197 status = pthread_mutex_unlock(_mutex); 5198 assert_status(status == 0, status, "mutex_unlock"); 5199 if (AnyWaiters != 0) { 5200 status = pthread_cond_signal(_cond); 5201 assert_status(status == 0, status, "cond_signal"); 5202 } 5203 5204 // Note that we signal() _after dropping the lock for "immortal" Events. 5205 // This is safe and avoids a common class of futile wakeups. In rare 5206 // circumstances this can cause a thread to return prematurely from 5207 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 5208 // simply re-test the condition and re-park itself. 5209} 5210 5211 5212// JSR166 5213// ------------------------------------------------------- 5214 5215/* 5216 * The solaris and linux implementations of park/unpark are fairly 5217 * conservative for now, but can be improved. They currently use a 5218 * mutex/condvar pair, plus a a count. 5219 * Park decrements count if > 0, else does a condvar wait. Unpark 5220 * sets count to 1 and signals condvar. Only one thread ever waits 5221 * on the condvar. Contention seen when trying to park implies that someone 5222 * is unparking you, so don't wait. And spurious returns are fine, so there 5223 * is no need to track notifications. 5224 */ 5225 5226#define MAX_SECS 100000000 5227/* 5228 * This code is common to linux and solaris and will be moved to a 5229 * common place in dolphin. 5230 * 5231 * The passed in time value is either a relative time in nanoseconds 5232 * or an absolute time in milliseconds. Either way it has to be unpacked 5233 * into suitable seconds and nanoseconds components and stored in the 5234 * given timespec structure. 5235 * Given time is a 64-bit value and the time_t used in the timespec is only 5236 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 5237 * overflow if times way in the future are given. Further on Solaris versions 5238 * prior to 10 there is a restriction (see cond_timedwait) that the specified 5239 * number of seconds, in abstime, is less than current_time + 100,000,000. 5240 * As it will be 28 years before "now + 100000000" will overflow we can 5241 * ignore overflow and just impose a hard-limit on seconds using the value 5242 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 5243 * years from "now". 5244 */ 5245 5246static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5247 assert (time > 0, "convertTime"); 5248 5249 struct timeval now; 5250 int status = gettimeofday(&now, NULL); 5251 assert(status == 0, "gettimeofday"); 5252 5253 time_t max_secs = now.tv_sec + MAX_SECS; 5254 5255 if (isAbsolute) { 5256 jlong secs = time / 1000; 5257 if (secs > max_secs) { 5258 absTime->tv_sec = max_secs; 5259 } 5260 else { 5261 absTime->tv_sec = secs; 5262 } 5263 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5264 } 5265 else { 5266 jlong secs = time / NANOSECS_PER_SEC; 5267 if (secs >= MAX_SECS) { 5268 absTime->tv_sec = max_secs; 5269 absTime->tv_nsec = 0; 5270 } 5271 else { 5272 absTime->tv_sec = now.tv_sec + secs; 5273 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5274 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5275 absTime->tv_nsec -= NANOSECS_PER_SEC; 5276 ++absTime->tv_sec; // note: this must be <= max_secs 5277 } 5278 } 5279 } 5280 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5281 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5282 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5283 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5284} 5285 5286void Parker::park(bool isAbsolute, jlong time) { 5287 // Ideally we'd do something useful while spinning, such 5288 // as calling unpackTime(). 5289 5290 // Optional fast-path check: 5291 // Return immediately if a permit is available. 5292 // We depend on Atomic::xchg() having full barrier semantics 5293 // since we are doing a lock-free update to _counter. 5294 if (Atomic::xchg(0, &_counter) > 0) return; 5295 5296 Thread* thread = Thread::current(); 5297 assert(thread->is_Java_thread(), "Must be JavaThread"); 5298 JavaThread *jt = (JavaThread *)thread; 5299 5300 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5301 // Check interrupt before trying to wait 5302 if (Thread::is_interrupted(thread, false)) { 5303 return; 5304 } 5305 5306 // Next, demultiplex/decode time arguments 5307 timespec absTime; 5308 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all 5309 return; 5310 } 5311 if (time > 0) { 5312 unpackTime(&absTime, isAbsolute, time); 5313 } 5314 5315 5316 // Enter safepoint region 5317 // Beware of deadlocks such as 6317397. 5318 // The per-thread Parker:: mutex is a classic leaf-lock. 5319 // In particular a thread must never block on the Threads_lock while 5320 // holding the Parker:: mutex. If safepoints are pending both the 5321 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5322 ThreadBlockInVM tbivm(jt); 5323 5324 // Don't wait if cannot get lock since interference arises from 5325 // unblocking. Also. check interrupt before trying wait 5326 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5327 return; 5328 } 5329 5330 int status ; 5331 if (_counter > 0) { // no wait needed 5332 _counter = 0; 5333 status = pthread_mutex_unlock(_mutex); 5334 assert (status == 0, "invariant") ; 5335 // Paranoia to ensure our locked and lock-free paths interact 5336 // correctly with each other and Java-level accesses. 5337 OrderAccess::fence(); 5338 return; 5339 } 5340 5341#ifdef ASSERT 5342 // Don't catch signals while blocked; let the running threads have the signals. 5343 // (This allows a debugger to break into the running thread.) 5344 sigset_t oldsigs; 5345 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5346 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5347#endif 5348 5349 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5350 jt->set_suspend_equivalent(); 5351 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5352 5353 if (time == 0) { 5354 status = pthread_cond_wait (_cond, _mutex) ; 5355 } else { 5356 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ; 5357 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5358 pthread_cond_destroy (_cond) ; 5359 pthread_cond_init (_cond, NULL); 5360 } 5361 } 5362 assert_status(status == 0 || status == EINTR || 5363 status == ETIME || status == ETIMEDOUT, 5364 status, "cond_timedwait"); 5365 5366#ifdef ASSERT 5367 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5368#endif 5369 5370 _counter = 0 ; 5371 status = pthread_mutex_unlock(_mutex) ; 5372 assert_status(status == 0, status, "invariant") ; 5373 // Paranoia to ensure our locked and lock-free paths interact 5374 // correctly with each other and Java-level accesses. 5375 OrderAccess::fence(); 5376 5377 // If externally suspended while waiting, re-suspend 5378 if (jt->handle_special_suspend_equivalent_condition()) { 5379 jt->java_suspend_self(); 5380 } 5381} 5382 5383void Parker::unpark() { 5384 int s, status ; 5385 status = pthread_mutex_lock(_mutex); 5386 assert (status == 0, "invariant") ; 5387 s = _counter; 5388 _counter = 1; 5389 if (s < 1) { 5390 if (WorkAroundNPTLTimedWaitHang) { 5391 status = pthread_cond_signal (_cond) ; 5392 assert (status == 0, "invariant") ; 5393 status = pthread_mutex_unlock(_mutex); 5394 assert (status == 0, "invariant") ; 5395 } else { 5396 status = pthread_mutex_unlock(_mutex); 5397 assert (status == 0, "invariant") ; 5398 status = pthread_cond_signal (_cond) ; 5399 assert (status == 0, "invariant") ; 5400 } 5401 } else { 5402 pthread_mutex_unlock(_mutex); 5403 assert (status == 0, "invariant") ; 5404 } 5405} 5406 5407 5408extern char** environ; 5409 5410#ifndef __NR_fork 5411#define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5412#endif 5413 5414#ifndef __NR_execve 5415#define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 5416#endif 5417 5418// Run the specified command in a separate process. Return its exit value, 5419// or -1 on failure (e.g. can't fork a new process). 5420// Unlike system(), this function can be called from signal handler. It 5421// doesn't block SIGINT et al. 5422int os::fork_and_exec(char* cmd) { 5423 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5424 5425 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5426 // pthread_atfork handlers and reset pthread library. All we need is a 5427 // separate process to execve. Make a direct syscall to fork process. 5428 // On IA64 there's no fork syscall, we have to use fork() and hope for 5429 // the best... 5430 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5431 IA64_ONLY(fork();) 5432 5433 if (pid < 0) { 5434 // fork failed 5435 return -1; 5436 5437 } else if (pid == 0) { 5438 // child process 5439 5440 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5441 // first to kill every thread on the thread list. Because this list is 5442 // not reset by fork() (see notes above), execve() will instead kill 5443 // every thread in the parent process. We know this is the only thread 5444 // in the new process, so make a system call directly. 5445 // IA64 should use normal execve() from glibc to match the glibc fork() 5446 // above. 5447 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5448 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5449 5450 // execve failed 5451 _exit(-1); 5452 5453 } else { 5454 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5455 // care about the actual exit code, for now. 5456 5457 int status; 5458 5459 // Wait for the child process to exit. This returns immediately if 5460 // the child has already exited. */ 5461 while (waitpid(pid, &status, 0) < 0) { 5462 switch (errno) { 5463 case ECHILD: return 0; 5464 case EINTR: break; 5465 default: return -1; 5466 } 5467 } 5468 5469 if (WIFEXITED(status)) { 5470 // The child exited normally; get its exit code. 5471 return WEXITSTATUS(status); 5472 } else if (WIFSIGNALED(status)) { 5473 // The child exited because of a signal 5474 // The best value to return is 0x80 + signal number, 5475 // because that is what all Unix shells do, and because 5476 // it allows callers to distinguish between process exit and 5477 // process death by signal. 5478 return 0x80 + WTERMSIG(status); 5479 } else { 5480 // Unknown exit code; pass it through 5481 return status; 5482 } 5483 } 5484} 5485 5486// is_headless_jre() 5487// 5488// Test for the existence of xawt/libmawt.so or libawt_xawt.so 5489// in order to report if we are running in a headless jre 5490// 5491// Since JDK8 xawt/libmawt.so was moved into the same directory 5492// as libawt.so, and renamed libawt_xawt.so 5493// 5494bool os::is_headless_jre() { 5495 struct stat statbuf; 5496 char buf[MAXPATHLEN]; 5497 char libmawtpath[MAXPATHLEN]; 5498 const char *xawtstr = "/xawt/libmawt.so"; 5499 const char *new_xawtstr = "/libawt_xawt.so"; 5500 char *p; 5501 5502 // Get path to libjvm.so 5503 os::jvm_path(buf, sizeof(buf)); 5504 5505 // Get rid of libjvm.so 5506 p = strrchr(buf, '/'); 5507 if (p == NULL) return false; 5508 else *p = '\0'; 5509 5510 // Get rid of client or server 5511 p = strrchr(buf, '/'); 5512 if (p == NULL) return false; 5513 else *p = '\0'; 5514 5515 // check xawt/libmawt.so 5516 strcpy(libmawtpath, buf); 5517 strcat(libmawtpath, xawtstr); 5518 if (::stat(libmawtpath, &statbuf) == 0) return false; 5519 5520 // check libawt_xawt.so 5521 strcpy(libmawtpath, buf); 5522 strcat(libmawtpath, new_xawtstr); 5523 if (::stat(libmawtpath, &statbuf) == 0) return false; 5524 5525 return true; 5526} 5527 5528// Get the default path to the core file 5529// Returns the length of the string 5530int os::get_core_path(char* buffer, size_t bufferSize) { 5531 const char* p = get_current_directory(buffer, bufferSize); 5532 5533 if (p == NULL) { 5534 assert(p != NULL, "failed to get current directory"); 5535 return 0; 5536 } 5537 5538 return strlen(buffer); 5539} 5540 5541#ifdef JAVASE_EMBEDDED 5542// 5543// A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory. 5544// 5545MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL; 5546 5547// ctor 5548// 5549MemNotifyThread::MemNotifyThread(int fd): Thread() { 5550 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread"); 5551 _fd = fd; 5552 5553 if (os::create_thread(this, os::os_thread)) { 5554 _memnotify_thread = this; 5555 os::set_priority(this, NearMaxPriority); 5556 os::start_thread(this); 5557 } 5558} 5559 5560// Where all the work gets done 5561// 5562void MemNotifyThread::run() { 5563 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread"); 5564 5565 // Set up the select arguments 5566 fd_set rfds; 5567 if (_fd != -1) { 5568 FD_ZERO(&rfds); 5569 FD_SET(_fd, &rfds); 5570 } 5571 5572 // Now wait for the mem_notify device to wake up 5573 while (1) { 5574 // Wait for the mem_notify device to signal us.. 5575 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL); 5576 if (rc == -1) { 5577 perror("select!\n"); 5578 break; 5579 } else if (rc) { 5580 //ssize_t free_before = os::available_memory(); 5581 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024); 5582 5583 // The kernel is telling us there is not much memory left... 5584 // try to do something about that 5585 5586 // If we are not already in a GC, try one. 5587 if (!Universe::heap()->is_gc_active()) { 5588 Universe::heap()->collect(GCCause::_allocation_failure); 5589 5590 //ssize_t free_after = os::available_memory(); 5591 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024); 5592 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024); 5593 } 5594 // We might want to do something like the following if we find the GC's are not helping... 5595 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true); 5596 } 5597 } 5598} 5599 5600// 5601// See if the /dev/mem_notify device exists, and if so, start a thread to monitor it. 5602// 5603void MemNotifyThread::start() { 5604 int fd; 5605 fd = open ("/dev/mem_notify", O_RDONLY, 0); 5606 if (fd < 0) { 5607 return; 5608 } 5609 5610 if (memnotify_thread() == NULL) { 5611 new MemNotifyThread(fd); 5612 } 5613} 5614#endif // JAVASE_EMBEDDED 5615