os_linux.cpp revision 5430:aa6f2ea19d8f
1/* 2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25// no precompiled headers 26#include "classfile/classLoader.hpp" 27#include "classfile/systemDictionary.hpp" 28#include "classfile/vmSymbols.hpp" 29#include "code/icBuffer.hpp" 30#include "code/vtableStubs.hpp" 31#include "compiler/compileBroker.hpp" 32#include "compiler/disassembler.hpp" 33#include "interpreter/interpreter.hpp" 34#include "jvm_linux.h" 35#include "memory/allocation.inline.hpp" 36#include "memory/filemap.hpp" 37#include "mutex_linux.inline.hpp" 38#include "oops/oop.inline.hpp" 39#include "os_share_linux.hpp" 40#include "prims/jniFastGetField.hpp" 41#include "prims/jvm.h" 42#include "prims/jvm_misc.hpp" 43#include "runtime/arguments.hpp" 44#include "runtime/extendedPC.hpp" 45#include "runtime/globals.hpp" 46#include "runtime/interfaceSupport.hpp" 47#include "runtime/init.hpp" 48#include "runtime/java.hpp" 49#include "runtime/javaCalls.hpp" 50#include "runtime/mutexLocker.hpp" 51#include "runtime/objectMonitor.hpp" 52#include "runtime/osThread.hpp" 53#include "runtime/perfMemory.hpp" 54#include "runtime/sharedRuntime.hpp" 55#include "runtime/statSampler.hpp" 56#include "runtime/stubRoutines.hpp" 57#include "runtime/thread.inline.hpp" 58#include "runtime/threadCritical.hpp" 59#include "runtime/timer.hpp" 60#include "services/attachListener.hpp" 61#include "services/memTracker.hpp" 62#include "services/runtimeService.hpp" 63#include "utilities/decoder.hpp" 64#include "utilities/defaultStream.hpp" 65#include "utilities/events.hpp" 66#include "utilities/elfFile.hpp" 67#include "utilities/growableArray.hpp" 68#include "utilities/vmError.hpp" 69 70// put OS-includes here 71# include <sys/types.h> 72# include <sys/mman.h> 73# include <sys/stat.h> 74# include <sys/select.h> 75# include <pthread.h> 76# include <signal.h> 77# include <errno.h> 78# include <dlfcn.h> 79# include <stdio.h> 80# include <unistd.h> 81# include <sys/resource.h> 82# include <pthread.h> 83# include <sys/stat.h> 84# include <sys/time.h> 85# include <sys/times.h> 86# include <sys/utsname.h> 87# include <sys/socket.h> 88# include <sys/wait.h> 89# include <pwd.h> 90# include <poll.h> 91# include <semaphore.h> 92# include <fcntl.h> 93# include <string.h> 94# include <syscall.h> 95# include <sys/sysinfo.h> 96# include <gnu/libc-version.h> 97# include <sys/ipc.h> 98# include <sys/shm.h> 99# include <link.h> 100# include <stdint.h> 101# include <inttypes.h> 102# include <sys/ioctl.h> 103 104// if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling 105// getrusage() is prepared to handle the associated failure. 106#ifndef RUSAGE_THREAD 107#define RUSAGE_THREAD (1) /* only the calling thread */ 108#endif 109 110#define MAX_PATH (2 * K) 111 112// for timer info max values which include all bits 113#define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 114 115#define LARGEPAGES_BIT (1 << 6) 116//////////////////////////////////////////////////////////////////////////////// 117// global variables 118julong os::Linux::_physical_memory = 0; 119 120address os::Linux::_initial_thread_stack_bottom = NULL; 121uintptr_t os::Linux::_initial_thread_stack_size = 0; 122 123int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 124int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 125Mutex* os::Linux::_createThread_lock = NULL; 126pthread_t os::Linux::_main_thread; 127int os::Linux::_page_size = -1; 128const int os::Linux::_vm_default_page_size = (8 * K); 129bool os::Linux::_is_floating_stack = false; 130bool os::Linux::_is_NPTL = false; 131bool os::Linux::_supports_fast_thread_cpu_time = false; 132const char * os::Linux::_glibc_version = NULL; 133const char * os::Linux::_libpthread_version = NULL; 134pthread_condattr_t os::Linux::_condattr[1]; 135 136static jlong initial_time_count=0; 137 138static int clock_tics_per_sec = 100; 139 140// For diagnostics to print a message once. see run_periodic_checks 141static sigset_t check_signal_done; 142static bool check_signals = true;; 143 144static pid_t _initial_pid = 0; 145 146/* Signal number used to suspend/resume a thread */ 147 148/* do not use any signal number less than SIGSEGV, see 4355769 */ 149static int SR_signum = SIGUSR2; 150sigset_t SR_sigset; 151 152/* Used to protect dlsym() calls */ 153static pthread_mutex_t dl_mutex; 154 155// Declarations 156static void unpackTime(timespec* absTime, bool isAbsolute, jlong time); 157 158#ifdef JAVASE_EMBEDDED 159class MemNotifyThread: public Thread { 160 friend class VMStructs; 161 public: 162 virtual void run(); 163 164 private: 165 static MemNotifyThread* _memnotify_thread; 166 int _fd; 167 168 public: 169 170 // Constructor 171 MemNotifyThread(int fd); 172 173 // Tester 174 bool is_memnotify_thread() const { return true; } 175 176 // Printing 177 char* name() const { return (char*)"Linux MemNotify Thread"; } 178 179 // Returns the single instance of the MemNotifyThread 180 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; } 181 182 // Create and start the single instance of MemNotifyThread 183 static void start(); 184}; 185#endif // JAVASE_EMBEDDED 186 187// utility functions 188 189static int SR_initialize(); 190 191julong os::available_memory() { 192 return Linux::available_memory(); 193} 194 195julong os::Linux::available_memory() { 196 // values in struct sysinfo are "unsigned long" 197 struct sysinfo si; 198 sysinfo(&si); 199 200 return (julong)si.freeram * si.mem_unit; 201} 202 203julong os::physical_memory() { 204 return Linux::physical_memory(); 205} 206 207//////////////////////////////////////////////////////////////////////////////// 208// environment support 209 210bool os::getenv(const char* name, char* buf, int len) { 211 const char* val = ::getenv(name); 212 if (val != NULL && strlen(val) < (size_t)len) { 213 strcpy(buf, val); 214 return true; 215 } 216 if (len > 0) buf[0] = 0; // return a null string 217 return false; 218} 219 220 221// Return true if user is running as root. 222 223bool os::have_special_privileges() { 224 static bool init = false; 225 static bool privileges = false; 226 if (!init) { 227 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 228 init = true; 229 } 230 return privileges; 231} 232 233 234#ifndef SYS_gettid 235// i386: 224, ia64: 1105, amd64: 186, sparc 143 236#ifdef __ia64__ 237#define SYS_gettid 1105 238#elif __i386__ 239#define SYS_gettid 224 240#elif __amd64__ 241#define SYS_gettid 186 242#elif __sparc__ 243#define SYS_gettid 143 244#else 245#error define gettid for the arch 246#endif 247#endif 248 249// Cpu architecture string 250#if defined(ZERO) 251static char cpu_arch[] = ZERO_LIBARCH; 252#elif defined(IA64) 253static char cpu_arch[] = "ia64"; 254#elif defined(IA32) 255static char cpu_arch[] = "i386"; 256#elif defined(AMD64) 257static char cpu_arch[] = "amd64"; 258#elif defined(ARM) 259static char cpu_arch[] = "arm"; 260#elif defined(PPC) 261static char cpu_arch[] = "ppc"; 262#elif defined(SPARC) 263# ifdef _LP64 264static char cpu_arch[] = "sparcv9"; 265# else 266static char cpu_arch[] = "sparc"; 267# endif 268#else 269#error Add appropriate cpu_arch setting 270#endif 271 272 273// pid_t gettid() 274// 275// Returns the kernel thread id of the currently running thread. Kernel 276// thread id is used to access /proc. 277// 278// (Note that getpid() on LinuxThreads returns kernel thread id too; but 279// on NPTL, it returns the same pid for all threads, as required by POSIX.) 280// 281pid_t os::Linux::gettid() { 282 int rslt = syscall(SYS_gettid); 283 if (rslt == -1) { 284 // old kernel, no NPTL support 285 return getpid(); 286 } else { 287 return (pid_t)rslt; 288 } 289} 290 291// Most versions of linux have a bug where the number of processors are 292// determined by looking at the /proc file system. In a chroot environment, 293// the system call returns 1. This causes the VM to act as if it is 294// a single processor and elide locking (see is_MP() call). 295static bool unsafe_chroot_detected = false; 296static const char *unstable_chroot_error = "/proc file system not found.\n" 297 "Java may be unstable running multithreaded in a chroot " 298 "environment on Linux when /proc filesystem is not mounted."; 299 300void os::Linux::initialize_system_info() { 301 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 302 if (processor_count() == 1) { 303 pid_t pid = os::Linux::gettid(); 304 char fname[32]; 305 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 306 FILE *fp = fopen(fname, "r"); 307 if (fp == NULL) { 308 unsafe_chroot_detected = true; 309 } else { 310 fclose(fp); 311 } 312 } 313 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 314 assert(processor_count() > 0, "linux error"); 315} 316 317void os::init_system_properties_values() { 318// char arch[12]; 319// sysinfo(SI_ARCHITECTURE, arch, sizeof(arch)); 320 321 // The next steps are taken in the product version: 322 // 323 // Obtain the JAVA_HOME value from the location of libjvm.so. 324 // This library should be located at: 325 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 326 // 327 // If "/jre/lib/" appears at the right place in the path, then we 328 // assume libjvm.so is installed in a JDK and we use this path. 329 // 330 // Otherwise exit with message: "Could not create the Java virtual machine." 331 // 332 // The following extra steps are taken in the debugging version: 333 // 334 // If "/jre/lib/" does NOT appear at the right place in the path 335 // instead of exit check for $JAVA_HOME environment variable. 336 // 337 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 338 // then we append a fake suffix "hotspot/libjvm.so" to this path so 339 // it looks like libjvm.so is installed there 340 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 341 // 342 // Otherwise exit. 343 // 344 // Important note: if the location of libjvm.so changes this 345 // code needs to be changed accordingly. 346 347 // The next few definitions allow the code to be verbatim: 348#define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n), mtInternal) 349#define getenv(n) ::getenv(n) 350 351/* 352 * See ld(1): 353 * The linker uses the following search paths to locate required 354 * shared libraries: 355 * 1: ... 356 * ... 357 * 7: The default directories, normally /lib and /usr/lib. 358 */ 359#if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 360#define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 361#else 362#define DEFAULT_LIBPATH "/lib:/usr/lib" 363#endif 364 365#define EXTENSIONS_DIR "/lib/ext" 366#define ENDORSED_DIR "/lib/endorsed" 367#define REG_DIR "/usr/java/packages" 368 369 { 370 /* sysclasspath, java_home, dll_dir */ 371 { 372 char *home_path; 373 char *dll_path; 374 char *pslash; 375 char buf[MAXPATHLEN]; 376 os::jvm_path(buf, sizeof(buf)); 377 378 // Found the full path to libjvm.so. 379 // Now cut the path to <java_home>/jre if we can. 380 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */ 381 pslash = strrchr(buf, '/'); 382 if (pslash != NULL) 383 *pslash = '\0'; /* get rid of /{client|server|hotspot} */ 384 dll_path = malloc(strlen(buf) + 1); 385 if (dll_path == NULL) 386 return; 387 strcpy(dll_path, buf); 388 Arguments::set_dll_dir(dll_path); 389 390 if (pslash != NULL) { 391 pslash = strrchr(buf, '/'); 392 if (pslash != NULL) { 393 *pslash = '\0'; /* get rid of /<arch> */ 394 pslash = strrchr(buf, '/'); 395 if (pslash != NULL) 396 *pslash = '\0'; /* get rid of /lib */ 397 } 398 } 399 400 home_path = malloc(strlen(buf) + 1); 401 if (home_path == NULL) 402 return; 403 strcpy(home_path, buf); 404 Arguments::set_java_home(home_path); 405 406 if (!set_boot_path('/', ':')) 407 return; 408 } 409 410 /* 411 * Where to look for native libraries 412 * 413 * Note: Due to a legacy implementation, most of the library path 414 * is set in the launcher. This was to accomodate linking restrictions 415 * on legacy Linux implementations (which are no longer supported). 416 * Eventually, all the library path setting will be done here. 417 * 418 * However, to prevent the proliferation of improperly built native 419 * libraries, the new path component /usr/java/packages is added here. 420 * Eventually, all the library path setting will be done here. 421 */ 422 { 423 char *ld_library_path; 424 425 /* 426 * Construct the invariant part of ld_library_path. Note that the 427 * space for the colon and the trailing null are provided by the 428 * nulls included by the sizeof operator (so actually we allocate 429 * a byte more than necessary). 430 */ 431 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") + 432 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH)); 433 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch); 434 435 /* 436 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It 437 * should always exist (until the legacy problem cited above is 438 * addressed). 439 */ 440 char *v = getenv("LD_LIBRARY_PATH"); 441 if (v != NULL) { 442 char *t = ld_library_path; 443 /* That's +1 for the colon and +1 for the trailing '\0' */ 444 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1); 445 sprintf(ld_library_path, "%s:%s", v, t); 446 } 447 Arguments::set_library_path(ld_library_path); 448 } 449 450 /* 451 * Extensions directories. 452 * 453 * Note that the space for the colon and the trailing null are provided 454 * by the nulls included by the sizeof operator (so actually one byte more 455 * than necessary is allocated). 456 */ 457 { 458 char *buf = malloc(strlen(Arguments::get_java_home()) + 459 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR)); 460 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR, 461 Arguments::get_java_home()); 462 Arguments::set_ext_dirs(buf); 463 } 464 465 /* Endorsed standards default directory. */ 466 { 467 char * buf; 468 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR)); 469 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 470 Arguments::set_endorsed_dirs(buf); 471 } 472 } 473 474#undef malloc 475#undef getenv 476#undef EXTENSIONS_DIR 477#undef ENDORSED_DIR 478 479 // Done 480 return; 481} 482 483//////////////////////////////////////////////////////////////////////////////// 484// breakpoint support 485 486void os::breakpoint() { 487 BREAKPOINT; 488} 489 490extern "C" void breakpoint() { 491 // use debugger to set breakpoint here 492} 493 494//////////////////////////////////////////////////////////////////////////////// 495// signal support 496 497debug_only(static bool signal_sets_initialized = false); 498static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 499 500bool os::Linux::is_sig_ignored(int sig) { 501 struct sigaction oact; 502 sigaction(sig, (struct sigaction*)NULL, &oact); 503 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 504 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 505 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 506 return true; 507 else 508 return false; 509} 510 511void os::Linux::signal_sets_init() { 512 // Should also have an assertion stating we are still single-threaded. 513 assert(!signal_sets_initialized, "Already initialized"); 514 // Fill in signals that are necessarily unblocked for all threads in 515 // the VM. Currently, we unblock the following signals: 516 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 517 // by -Xrs (=ReduceSignalUsage)); 518 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 519 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 520 // the dispositions or masks wrt these signals. 521 // Programs embedding the VM that want to use the above signals for their 522 // own purposes must, at this time, use the "-Xrs" option to prevent 523 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 524 // (See bug 4345157, and other related bugs). 525 // In reality, though, unblocking these signals is really a nop, since 526 // these signals are not blocked by default. 527 sigemptyset(&unblocked_sigs); 528 sigemptyset(&allowdebug_blocked_sigs); 529 sigaddset(&unblocked_sigs, SIGILL); 530 sigaddset(&unblocked_sigs, SIGSEGV); 531 sigaddset(&unblocked_sigs, SIGBUS); 532 sigaddset(&unblocked_sigs, SIGFPE); 533 sigaddset(&unblocked_sigs, SR_signum); 534 535 if (!ReduceSignalUsage) { 536 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 537 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 538 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 539 } 540 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 541 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 542 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 543 } 544 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 545 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 546 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 547 } 548 } 549 // Fill in signals that are blocked by all but the VM thread. 550 sigemptyset(&vm_sigs); 551 if (!ReduceSignalUsage) 552 sigaddset(&vm_sigs, BREAK_SIGNAL); 553 debug_only(signal_sets_initialized = true); 554 555} 556 557// These are signals that are unblocked while a thread is running Java. 558// (For some reason, they get blocked by default.) 559sigset_t* os::Linux::unblocked_signals() { 560 assert(signal_sets_initialized, "Not initialized"); 561 return &unblocked_sigs; 562} 563 564// These are the signals that are blocked while a (non-VM) thread is 565// running Java. Only the VM thread handles these signals. 566sigset_t* os::Linux::vm_signals() { 567 assert(signal_sets_initialized, "Not initialized"); 568 return &vm_sigs; 569} 570 571// These are signals that are blocked during cond_wait to allow debugger in 572sigset_t* os::Linux::allowdebug_blocked_signals() { 573 assert(signal_sets_initialized, "Not initialized"); 574 return &allowdebug_blocked_sigs; 575} 576 577void os::Linux::hotspot_sigmask(Thread* thread) { 578 579 //Save caller's signal mask before setting VM signal mask 580 sigset_t caller_sigmask; 581 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 582 583 OSThread* osthread = thread->osthread(); 584 osthread->set_caller_sigmask(caller_sigmask); 585 586 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 587 588 if (!ReduceSignalUsage) { 589 if (thread->is_VM_thread()) { 590 // Only the VM thread handles BREAK_SIGNAL ... 591 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 592 } else { 593 // ... all other threads block BREAK_SIGNAL 594 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 595 } 596 } 597} 598 599////////////////////////////////////////////////////////////////////////////// 600// detecting pthread library 601 602void os::Linux::libpthread_init() { 603 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 604 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 605 // generic name for earlier versions. 606 // Define macros here so we can build HotSpot on old systems. 607# ifndef _CS_GNU_LIBC_VERSION 608# define _CS_GNU_LIBC_VERSION 2 609# endif 610# ifndef _CS_GNU_LIBPTHREAD_VERSION 611# define _CS_GNU_LIBPTHREAD_VERSION 3 612# endif 613 614 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 615 if (n > 0) { 616 char *str = (char *)malloc(n, mtInternal); 617 confstr(_CS_GNU_LIBC_VERSION, str, n); 618 os::Linux::set_glibc_version(str); 619 } else { 620 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 621 static char _gnu_libc_version[32]; 622 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 623 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 624 os::Linux::set_glibc_version(_gnu_libc_version); 625 } 626 627 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 628 if (n > 0) { 629 char *str = (char *)malloc(n, mtInternal); 630 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 631 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 632 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 633 // is the case. LinuxThreads has a hard limit on max number of threads. 634 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 635 // On the other hand, NPTL does not have such a limit, sysconf() 636 // will return -1 and errno is not changed. Check if it is really NPTL. 637 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 638 strstr(str, "NPTL") && 639 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 640 free(str); 641 os::Linux::set_libpthread_version("linuxthreads"); 642 } else { 643 os::Linux::set_libpthread_version(str); 644 } 645 } else { 646 // glibc before 2.3.2 only has LinuxThreads. 647 os::Linux::set_libpthread_version("linuxthreads"); 648 } 649 650 if (strstr(libpthread_version(), "NPTL")) { 651 os::Linux::set_is_NPTL(); 652 } else { 653 os::Linux::set_is_LinuxThreads(); 654 } 655 656 // LinuxThreads have two flavors: floating-stack mode, which allows variable 657 // stack size; and fixed-stack mode. NPTL is always floating-stack. 658 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 659 os::Linux::set_is_floating_stack(); 660 } 661} 662 663///////////////////////////////////////////////////////////////////////////// 664// thread stack 665 666// Force Linux kernel to expand current thread stack. If "bottom" is close 667// to the stack guard, caller should block all signals. 668// 669// MAP_GROWSDOWN: 670// A special mmap() flag that is used to implement thread stacks. It tells 671// kernel that the memory region should extend downwards when needed. This 672// allows early versions of LinuxThreads to only mmap the first few pages 673// when creating a new thread. Linux kernel will automatically expand thread 674// stack as needed (on page faults). 675// 676// However, because the memory region of a MAP_GROWSDOWN stack can grow on 677// demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 678// region, it's hard to tell if the fault is due to a legitimate stack 679// access or because of reading/writing non-exist memory (e.g. buffer 680// overrun). As a rule, if the fault happens below current stack pointer, 681// Linux kernel does not expand stack, instead a SIGSEGV is sent to the 682// application (see Linux kernel fault.c). 683// 684// This Linux feature can cause SIGSEGV when VM bangs thread stack for 685// stack overflow detection. 686// 687// Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 688// not use this flag. However, the stack of initial thread is not created 689// by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 690// unlikely) that user code can create a thread with MAP_GROWSDOWN stack 691// and then attach the thread to JVM. 692// 693// To get around the problem and allow stack banging on Linux, we need to 694// manually expand thread stack after receiving the SIGSEGV. 695// 696// There are two ways to expand thread stack to address "bottom", we used 697// both of them in JVM before 1.5: 698// 1. adjust stack pointer first so that it is below "bottom", and then 699// touch "bottom" 700// 2. mmap() the page in question 701// 702// Now alternate signal stack is gone, it's harder to use 2. For instance, 703// if current sp is already near the lower end of page 101, and we need to 704// call mmap() to map page 100, it is possible that part of the mmap() frame 705// will be placed in page 100. When page 100 is mapped, it is zero-filled. 706// That will destroy the mmap() frame and cause VM to crash. 707// 708// The following code works by adjusting sp first, then accessing the "bottom" 709// page to force a page fault. Linux kernel will then automatically expand the 710// stack mapping. 711// 712// _expand_stack_to() assumes its frame size is less than page size, which 713// should always be true if the function is not inlined. 714 715#if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 716#define NOINLINE 717#else 718#define NOINLINE __attribute__ ((noinline)) 719#endif 720 721static void _expand_stack_to(address bottom) NOINLINE; 722 723static void _expand_stack_to(address bottom) { 724 address sp; 725 size_t size; 726 volatile char *p; 727 728 // Adjust bottom to point to the largest address within the same page, it 729 // gives us a one-page buffer if alloca() allocates slightly more memory. 730 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 731 bottom += os::Linux::page_size() - 1; 732 733 // sp might be slightly above current stack pointer; if that's the case, we 734 // will alloca() a little more space than necessary, which is OK. Don't use 735 // os::current_stack_pointer(), as its result can be slightly below current 736 // stack pointer, causing us to not alloca enough to reach "bottom". 737 sp = (address)&sp; 738 739 if (sp > bottom) { 740 size = sp - bottom; 741 p = (volatile char *)alloca(size); 742 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 743 p[0] = '\0'; 744 } 745} 746 747bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 748 assert(t!=NULL, "just checking"); 749 assert(t->osthread()->expanding_stack(), "expand should be set"); 750 assert(t->stack_base() != NULL, "stack_base was not initialized"); 751 752 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 753 sigset_t mask_all, old_sigset; 754 sigfillset(&mask_all); 755 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 756 _expand_stack_to(addr); 757 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 758 return true; 759 } 760 return false; 761} 762 763////////////////////////////////////////////////////////////////////////////// 764// create new thread 765 766static address highest_vm_reserved_address(); 767 768// check if it's safe to start a new thread 769static bool _thread_safety_check(Thread* thread) { 770 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 771 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 772 // Heap is mmap'ed at lower end of memory space. Thread stacks are 773 // allocated (MAP_FIXED) from high address space. Every thread stack 774 // occupies a fixed size slot (usually 2Mbytes, but user can change 775 // it to other values if they rebuild LinuxThreads). 776 // 777 // Problem with MAP_FIXED is that mmap() can still succeed even part of 778 // the memory region has already been mmap'ed. That means if we have too 779 // many threads and/or very large heap, eventually thread stack will 780 // collide with heap. 781 // 782 // Here we try to prevent heap/stack collision by comparing current 783 // stack bottom with the highest address that has been mmap'ed by JVM 784 // plus a safety margin for memory maps created by native code. 785 // 786 // This feature can be disabled by setting ThreadSafetyMargin to 0 787 // 788 if (ThreadSafetyMargin > 0) { 789 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 790 791 // not safe if our stack extends below the safety margin 792 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 793 } else { 794 return true; 795 } 796 } else { 797 // Floating stack LinuxThreads or NPTL: 798 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 799 // there's not enough space left, pthread_create() will fail. If we come 800 // here, that means enough space has been reserved for stack. 801 return true; 802 } 803} 804 805// Thread start routine for all newly created threads 806static void *java_start(Thread *thread) { 807 // Try to randomize the cache line index of hot stack frames. 808 // This helps when threads of the same stack traces evict each other's 809 // cache lines. The threads can be either from the same JVM instance, or 810 // from different JVM instances. The benefit is especially true for 811 // processors with hyperthreading technology. 812 static int counter = 0; 813 int pid = os::current_process_id(); 814 alloca(((pid ^ counter++) & 7) * 128); 815 816 ThreadLocalStorage::set_thread(thread); 817 818 OSThread* osthread = thread->osthread(); 819 Monitor* sync = osthread->startThread_lock(); 820 821 // non floating stack LinuxThreads needs extra check, see above 822 if (!_thread_safety_check(thread)) { 823 // notify parent thread 824 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 825 osthread->set_state(ZOMBIE); 826 sync->notify_all(); 827 return NULL; 828 } 829 830 // thread_id is kernel thread id (similar to Solaris LWP id) 831 osthread->set_thread_id(os::Linux::gettid()); 832 833 if (UseNUMA) { 834 int lgrp_id = os::numa_get_group_id(); 835 if (lgrp_id != -1) { 836 thread->set_lgrp_id(lgrp_id); 837 } 838 } 839 // initialize signal mask for this thread 840 os::Linux::hotspot_sigmask(thread); 841 842 // initialize floating point control register 843 os::Linux::init_thread_fpu_state(); 844 845 // handshaking with parent thread 846 { 847 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 848 849 // notify parent thread 850 osthread->set_state(INITIALIZED); 851 sync->notify_all(); 852 853 // wait until os::start_thread() 854 while (osthread->get_state() == INITIALIZED) { 855 sync->wait(Mutex::_no_safepoint_check_flag); 856 } 857 } 858 859 // call one more level start routine 860 thread->run(); 861 862 return 0; 863} 864 865bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 866 assert(thread->osthread() == NULL, "caller responsible"); 867 868 // Allocate the OSThread object 869 OSThread* osthread = new OSThread(NULL, NULL); 870 if (osthread == NULL) { 871 return false; 872 } 873 874 // set the correct thread state 875 osthread->set_thread_type(thr_type); 876 877 // Initial state is ALLOCATED but not INITIALIZED 878 osthread->set_state(ALLOCATED); 879 880 thread->set_osthread(osthread); 881 882 // init thread attributes 883 pthread_attr_t attr; 884 pthread_attr_init(&attr); 885 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 886 887 // stack size 888 if (os::Linux::supports_variable_stack_size()) { 889 // calculate stack size if it's not specified by caller 890 if (stack_size == 0) { 891 stack_size = os::Linux::default_stack_size(thr_type); 892 893 switch (thr_type) { 894 case os::java_thread: 895 // Java threads use ThreadStackSize which default value can be 896 // changed with the flag -Xss 897 assert (JavaThread::stack_size_at_create() > 0, "this should be set"); 898 stack_size = JavaThread::stack_size_at_create(); 899 break; 900 case os::compiler_thread: 901 if (CompilerThreadStackSize > 0) { 902 stack_size = (size_t)(CompilerThreadStackSize * K); 903 break; 904 } // else fall through: 905 // use VMThreadStackSize if CompilerThreadStackSize is not defined 906 case os::vm_thread: 907 case os::pgc_thread: 908 case os::cgc_thread: 909 case os::watcher_thread: 910 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 911 break; 912 } 913 } 914 915 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 916 pthread_attr_setstacksize(&attr, stack_size); 917 } else { 918 // let pthread_create() pick the default value. 919 } 920 921 // glibc guard page 922 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 923 924 ThreadState state; 925 926 { 927 // Serialize thread creation if we are running with fixed stack LinuxThreads 928 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 929 if (lock) { 930 os::Linux::createThread_lock()->lock_without_safepoint_check(); 931 } 932 933 pthread_t tid; 934 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 935 936 pthread_attr_destroy(&attr); 937 938 if (ret != 0) { 939 if (PrintMiscellaneous && (Verbose || WizardMode)) { 940 perror("pthread_create()"); 941 } 942 // Need to clean up stuff we've allocated so far 943 thread->set_osthread(NULL); 944 delete osthread; 945 if (lock) os::Linux::createThread_lock()->unlock(); 946 return false; 947 } 948 949 // Store pthread info into the OSThread 950 osthread->set_pthread_id(tid); 951 952 // Wait until child thread is either initialized or aborted 953 { 954 Monitor* sync_with_child = osthread->startThread_lock(); 955 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 956 while ((state = osthread->get_state()) == ALLOCATED) { 957 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 958 } 959 } 960 961 if (lock) { 962 os::Linux::createThread_lock()->unlock(); 963 } 964 } 965 966 // Aborted due to thread limit being reached 967 if (state == ZOMBIE) { 968 thread->set_osthread(NULL); 969 delete osthread; 970 return false; 971 } 972 973 // The thread is returned suspended (in state INITIALIZED), 974 // and is started higher up in the call chain 975 assert(state == INITIALIZED, "race condition"); 976 return true; 977} 978 979///////////////////////////////////////////////////////////////////////////// 980// attach existing thread 981 982// bootstrap the main thread 983bool os::create_main_thread(JavaThread* thread) { 984 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 985 return create_attached_thread(thread); 986} 987 988bool os::create_attached_thread(JavaThread* thread) { 989#ifdef ASSERT 990 thread->verify_not_published(); 991#endif 992 993 // Allocate the OSThread object 994 OSThread* osthread = new OSThread(NULL, NULL); 995 996 if (osthread == NULL) { 997 return false; 998 } 999 1000 // Store pthread info into the OSThread 1001 osthread->set_thread_id(os::Linux::gettid()); 1002 osthread->set_pthread_id(::pthread_self()); 1003 1004 // initialize floating point control register 1005 os::Linux::init_thread_fpu_state(); 1006 1007 // Initial thread state is RUNNABLE 1008 osthread->set_state(RUNNABLE); 1009 1010 thread->set_osthread(osthread); 1011 1012 if (UseNUMA) { 1013 int lgrp_id = os::numa_get_group_id(); 1014 if (lgrp_id != -1) { 1015 thread->set_lgrp_id(lgrp_id); 1016 } 1017 } 1018 1019 if (os::Linux::is_initial_thread()) { 1020 // If current thread is initial thread, its stack is mapped on demand, 1021 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 1022 // the entire stack region to avoid SEGV in stack banging. 1023 // It is also useful to get around the heap-stack-gap problem on SuSE 1024 // kernel (see 4821821 for details). We first expand stack to the top 1025 // of yellow zone, then enable stack yellow zone (order is significant, 1026 // enabling yellow zone first will crash JVM on SuSE Linux), so there 1027 // is no gap between the last two virtual memory regions. 1028 1029 JavaThread *jt = (JavaThread *)thread; 1030 address addr = jt->stack_yellow_zone_base(); 1031 assert(addr != NULL, "initialization problem?"); 1032 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 1033 1034 osthread->set_expanding_stack(); 1035 os::Linux::manually_expand_stack(jt, addr); 1036 osthread->clear_expanding_stack(); 1037 } 1038 1039 // initialize signal mask for this thread 1040 // and save the caller's signal mask 1041 os::Linux::hotspot_sigmask(thread); 1042 1043 return true; 1044} 1045 1046void os::pd_start_thread(Thread* thread) { 1047 OSThread * osthread = thread->osthread(); 1048 assert(osthread->get_state() != INITIALIZED, "just checking"); 1049 Monitor* sync_with_child = osthread->startThread_lock(); 1050 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 1051 sync_with_child->notify(); 1052} 1053 1054// Free Linux resources related to the OSThread 1055void os::free_thread(OSThread* osthread) { 1056 assert(osthread != NULL, "osthread not set"); 1057 1058 if (Thread::current()->osthread() == osthread) { 1059 // Restore caller's signal mask 1060 sigset_t sigmask = osthread->caller_sigmask(); 1061 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1062 } 1063 1064 delete osthread; 1065} 1066 1067////////////////////////////////////////////////////////////////////////////// 1068// thread local storage 1069 1070int os::allocate_thread_local_storage() { 1071 pthread_key_t key; 1072 int rslt = pthread_key_create(&key, NULL); 1073 assert(rslt == 0, "cannot allocate thread local storage"); 1074 return (int)key; 1075} 1076 1077// Note: This is currently not used by VM, as we don't destroy TLS key 1078// on VM exit. 1079void os::free_thread_local_storage(int index) { 1080 int rslt = pthread_key_delete((pthread_key_t)index); 1081 assert(rslt == 0, "invalid index"); 1082} 1083 1084void os::thread_local_storage_at_put(int index, void* value) { 1085 int rslt = pthread_setspecific((pthread_key_t)index, value); 1086 assert(rslt == 0, "pthread_setspecific failed"); 1087} 1088 1089extern "C" Thread* get_thread() { 1090 return ThreadLocalStorage::thread(); 1091} 1092 1093////////////////////////////////////////////////////////////////////////////// 1094// initial thread 1095 1096// Check if current thread is the initial thread, similar to Solaris thr_main. 1097bool os::Linux::is_initial_thread(void) { 1098 char dummy; 1099 // If called before init complete, thread stack bottom will be null. 1100 // Can be called if fatal error occurs before initialization. 1101 if (initial_thread_stack_bottom() == NULL) return false; 1102 assert(initial_thread_stack_bottom() != NULL && 1103 initial_thread_stack_size() != 0, 1104 "os::init did not locate initial thread's stack region"); 1105 if ((address)&dummy >= initial_thread_stack_bottom() && 1106 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1107 return true; 1108 else return false; 1109} 1110 1111// Find the virtual memory area that contains addr 1112static bool find_vma(address addr, address* vma_low, address* vma_high) { 1113 FILE *fp = fopen("/proc/self/maps", "r"); 1114 if (fp) { 1115 address low, high; 1116 while (!feof(fp)) { 1117 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1118 if (low <= addr && addr < high) { 1119 if (vma_low) *vma_low = low; 1120 if (vma_high) *vma_high = high; 1121 fclose (fp); 1122 return true; 1123 } 1124 } 1125 for (;;) { 1126 int ch = fgetc(fp); 1127 if (ch == EOF || ch == (int)'\n') break; 1128 } 1129 } 1130 fclose(fp); 1131 } 1132 return false; 1133} 1134 1135// Locate initial thread stack. This special handling of initial thread stack 1136// is needed because pthread_getattr_np() on most (all?) Linux distros returns 1137// bogus value for initial thread. 1138void os::Linux::capture_initial_stack(size_t max_size) { 1139 // stack size is the easy part, get it from RLIMIT_STACK 1140 size_t stack_size; 1141 struct rlimit rlim; 1142 getrlimit(RLIMIT_STACK, &rlim); 1143 stack_size = rlim.rlim_cur; 1144 1145 // 6308388: a bug in ld.so will relocate its own .data section to the 1146 // lower end of primordial stack; reduce ulimit -s value a little bit 1147 // so we won't install guard page on ld.so's data section. 1148 stack_size -= 2 * page_size(); 1149 1150 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1151 // 7.1, in both cases we will get 2G in return value. 1152 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1153 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1154 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1155 // in case other parts in glibc still assumes 2M max stack size. 1156 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1157 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1158 if (stack_size > 2 * K * K IA64_ONLY(*2)) 1159 stack_size = 2 * K * K IA64_ONLY(*2); 1160 // Try to figure out where the stack base (top) is. This is harder. 1161 // 1162 // When an application is started, glibc saves the initial stack pointer in 1163 // a global variable "__libc_stack_end", which is then used by system 1164 // libraries. __libc_stack_end should be pretty close to stack top. The 1165 // variable is available since the very early days. However, because it is 1166 // a private interface, it could disappear in the future. 1167 // 1168 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1169 // to __libc_stack_end, it is very close to stack top, but isn't the real 1170 // stack top. Note that /proc may not exist if VM is running as a chroot 1171 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1172 // /proc/<pid>/stat could change in the future (though unlikely). 1173 // 1174 // We try __libc_stack_end first. If that doesn't work, look for 1175 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1176 // as a hint, which should work well in most cases. 1177 1178 uintptr_t stack_start; 1179 1180 // try __libc_stack_end first 1181 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1182 if (p && *p) { 1183 stack_start = *p; 1184 } else { 1185 // see if we can get the start_stack field from /proc/self/stat 1186 FILE *fp; 1187 int pid; 1188 char state; 1189 int ppid; 1190 int pgrp; 1191 int session; 1192 int nr; 1193 int tpgrp; 1194 unsigned long flags; 1195 unsigned long minflt; 1196 unsigned long cminflt; 1197 unsigned long majflt; 1198 unsigned long cmajflt; 1199 unsigned long utime; 1200 unsigned long stime; 1201 long cutime; 1202 long cstime; 1203 long prio; 1204 long nice; 1205 long junk; 1206 long it_real; 1207 uintptr_t start; 1208 uintptr_t vsize; 1209 intptr_t rss; 1210 uintptr_t rsslim; 1211 uintptr_t scodes; 1212 uintptr_t ecode; 1213 int i; 1214 1215 // Figure what the primordial thread stack base is. Code is inspired 1216 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1217 // followed by command name surrounded by parentheses, state, etc. 1218 char stat[2048]; 1219 int statlen; 1220 1221 fp = fopen("/proc/self/stat", "r"); 1222 if (fp) { 1223 statlen = fread(stat, 1, 2047, fp); 1224 stat[statlen] = '\0'; 1225 fclose(fp); 1226 1227 // Skip pid and the command string. Note that we could be dealing with 1228 // weird command names, e.g. user could decide to rename java launcher 1229 // to "java 1.4.2 :)", then the stat file would look like 1230 // 1234 (java 1.4.2 :)) R ... ... 1231 // We don't really need to know the command string, just find the last 1232 // occurrence of ")" and then start parsing from there. See bug 4726580. 1233 char * s = strrchr(stat, ')'); 1234 1235 i = 0; 1236 if (s) { 1237 // Skip blank chars 1238 do s++; while (isspace(*s)); 1239 1240#define _UFM UINTX_FORMAT 1241#define _DFM INTX_FORMAT 1242 1243 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1244 /* 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 */ 1245 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, 1246 &state, /* 3 %c */ 1247 &ppid, /* 4 %d */ 1248 &pgrp, /* 5 %d */ 1249 &session, /* 6 %d */ 1250 &nr, /* 7 %d */ 1251 &tpgrp, /* 8 %d */ 1252 &flags, /* 9 %lu */ 1253 &minflt, /* 10 %lu */ 1254 &cminflt, /* 11 %lu */ 1255 &majflt, /* 12 %lu */ 1256 &cmajflt, /* 13 %lu */ 1257 &utime, /* 14 %lu */ 1258 &stime, /* 15 %lu */ 1259 &cutime, /* 16 %ld */ 1260 &cstime, /* 17 %ld */ 1261 &prio, /* 18 %ld */ 1262 &nice, /* 19 %ld */ 1263 &junk, /* 20 %ld */ 1264 &it_real, /* 21 %ld */ 1265 &start, /* 22 UINTX_FORMAT */ 1266 &vsize, /* 23 UINTX_FORMAT */ 1267 &rss, /* 24 INTX_FORMAT */ 1268 &rsslim, /* 25 UINTX_FORMAT */ 1269 &scodes, /* 26 UINTX_FORMAT */ 1270 &ecode, /* 27 UINTX_FORMAT */ 1271 &stack_start); /* 28 UINTX_FORMAT */ 1272 } 1273 1274#undef _UFM 1275#undef _DFM 1276 1277 if (i != 28 - 2) { 1278 assert(false, "Bad conversion from /proc/self/stat"); 1279 // product mode - assume we are the initial thread, good luck in the 1280 // embedded case. 1281 warning("Can't detect initial thread stack location - bad conversion"); 1282 stack_start = (uintptr_t) &rlim; 1283 } 1284 } else { 1285 // For some reason we can't open /proc/self/stat (for example, running on 1286 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1287 // most cases, so don't abort: 1288 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1289 stack_start = (uintptr_t) &rlim; 1290 } 1291 } 1292 1293 // Now we have a pointer (stack_start) very close to the stack top, the 1294 // next thing to do is to figure out the exact location of stack top. We 1295 // can find out the virtual memory area that contains stack_start by 1296 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1297 // and its upper limit is the real stack top. (again, this would fail if 1298 // running inside chroot, because /proc may not exist.) 1299 1300 uintptr_t stack_top; 1301 address low, high; 1302 if (find_vma((address)stack_start, &low, &high)) { 1303 // success, "high" is the true stack top. (ignore "low", because initial 1304 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1305 stack_top = (uintptr_t)high; 1306 } else { 1307 // failed, likely because /proc/self/maps does not exist 1308 warning("Can't detect initial thread stack location - find_vma failed"); 1309 // best effort: stack_start is normally within a few pages below the real 1310 // stack top, use it as stack top, and reduce stack size so we won't put 1311 // guard page outside stack. 1312 stack_top = stack_start; 1313 stack_size -= 16 * page_size(); 1314 } 1315 1316 // stack_top could be partially down the page so align it 1317 stack_top = align_size_up(stack_top, page_size()); 1318 1319 if (max_size && stack_size > max_size) { 1320 _initial_thread_stack_size = max_size; 1321 } else { 1322 _initial_thread_stack_size = stack_size; 1323 } 1324 1325 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1326 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1327} 1328 1329//////////////////////////////////////////////////////////////////////////////// 1330// time support 1331 1332// Time since start-up in seconds to a fine granularity. 1333// Used by VMSelfDestructTimer and the MemProfiler. 1334double os::elapsedTime() { 1335 1336 return (double)(os::elapsed_counter()) * 0.000001; 1337} 1338 1339jlong os::elapsed_counter() { 1340 timeval time; 1341 int status = gettimeofday(&time, NULL); 1342 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count; 1343} 1344 1345jlong os::elapsed_frequency() { 1346 return (1000 * 1000); 1347} 1348 1349bool os::supports_vtime() { return true; } 1350bool os::enable_vtime() { return false; } 1351bool os::vtime_enabled() { return false; } 1352 1353double os::elapsedVTime() { 1354 struct rusage usage; 1355 int retval = getrusage(RUSAGE_THREAD, &usage); 1356 if (retval == 0) { 1357 return (double) (usage.ru_utime.tv_sec + usage.ru_stime.tv_sec) + (double) (usage.ru_utime.tv_usec + usage.ru_stime.tv_usec) / (1000 * 1000); 1358 } else { 1359 // better than nothing, but not much 1360 return elapsedTime(); 1361 } 1362} 1363 1364jlong os::javaTimeMillis() { 1365 timeval time; 1366 int status = gettimeofday(&time, NULL); 1367 assert(status != -1, "linux error"); 1368 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1369} 1370 1371#ifndef CLOCK_MONOTONIC 1372#define CLOCK_MONOTONIC (1) 1373#endif 1374 1375void os::Linux::clock_init() { 1376 // we do dlopen's in this particular order due to bug in linux 1377 // dynamical loader (see 6348968) leading to crash on exit 1378 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1379 if (handle == NULL) { 1380 handle = dlopen("librt.so", RTLD_LAZY); 1381 } 1382 1383 if (handle) { 1384 int (*clock_getres_func)(clockid_t, struct timespec*) = 1385 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1386 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1387 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1388 if (clock_getres_func && clock_gettime_func) { 1389 // See if monotonic clock is supported by the kernel. Note that some 1390 // early implementations simply return kernel jiffies (updated every 1391 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1392 // for nano time (though the monotonic property is still nice to have). 1393 // It's fixed in newer kernels, however clock_getres() still returns 1394 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1395 // resolution for now. Hopefully as people move to new kernels, this 1396 // won't be a problem. 1397 struct timespec res; 1398 struct timespec tp; 1399 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1400 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1401 // yes, monotonic clock is supported 1402 _clock_gettime = clock_gettime_func; 1403 return; 1404 } else { 1405 // close librt if there is no monotonic clock 1406 dlclose(handle); 1407 } 1408 } 1409 } 1410 warning("No monotonic clock was available - timed services may " \ 1411 "be adversely affected if the time-of-day clock changes"); 1412} 1413 1414#ifndef SYS_clock_getres 1415 1416#if defined(IA32) || defined(AMD64) 1417#define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1418#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1419#else 1420#warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1421#define sys_clock_getres(x,y) -1 1422#endif 1423 1424#else 1425#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1426#endif 1427 1428void os::Linux::fast_thread_clock_init() { 1429 if (!UseLinuxPosixThreadCPUClocks) { 1430 return; 1431 } 1432 clockid_t clockid; 1433 struct timespec tp; 1434 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1435 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1436 1437 // Switch to using fast clocks for thread cpu time if 1438 // the sys_clock_getres() returns 0 error code. 1439 // Note, that some kernels may support the current thread 1440 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1441 // returned by the pthread_getcpuclockid(). 1442 // If the fast Posix clocks are supported then the sys_clock_getres() 1443 // must return at least tp.tv_sec == 0 which means a resolution 1444 // better than 1 sec. This is extra check for reliability. 1445 1446 if(pthread_getcpuclockid_func && 1447 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1448 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1449 1450 _supports_fast_thread_cpu_time = true; 1451 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1452 } 1453} 1454 1455jlong os::javaTimeNanos() { 1456 if (Linux::supports_monotonic_clock()) { 1457 struct timespec tp; 1458 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1459 assert(status == 0, "gettime error"); 1460 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1461 return result; 1462 } else { 1463 timeval time; 1464 int status = gettimeofday(&time, NULL); 1465 assert(status != -1, "linux error"); 1466 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1467 return 1000 * usecs; 1468 } 1469} 1470 1471void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1472 if (Linux::supports_monotonic_clock()) { 1473 info_ptr->max_value = ALL_64_BITS; 1474 1475 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1476 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1477 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1478 } else { 1479 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1480 info_ptr->max_value = ALL_64_BITS; 1481 1482 // gettimeofday is a real time clock so it skips 1483 info_ptr->may_skip_backward = true; 1484 info_ptr->may_skip_forward = true; 1485 } 1486 1487 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1488} 1489 1490// Return the real, user, and system times in seconds from an 1491// arbitrary fixed point in the past. 1492bool os::getTimesSecs(double* process_real_time, 1493 double* process_user_time, 1494 double* process_system_time) { 1495 struct tms ticks; 1496 clock_t real_ticks = times(&ticks); 1497 1498 if (real_ticks == (clock_t) (-1)) { 1499 return false; 1500 } else { 1501 double ticks_per_second = (double) clock_tics_per_sec; 1502 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1503 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1504 *process_real_time = ((double) real_ticks) / ticks_per_second; 1505 1506 return true; 1507 } 1508} 1509 1510 1511char * os::local_time_string(char *buf, size_t buflen) { 1512 struct tm t; 1513 time_t long_time; 1514 time(&long_time); 1515 localtime_r(&long_time, &t); 1516 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1517 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1518 t.tm_hour, t.tm_min, t.tm_sec); 1519 return buf; 1520} 1521 1522struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1523 return localtime_r(clock, res); 1524} 1525 1526//////////////////////////////////////////////////////////////////////////////// 1527// runtime exit support 1528 1529// Note: os::shutdown() might be called very early during initialization, or 1530// called from signal handler. Before adding something to os::shutdown(), make 1531// sure it is async-safe and can handle partially initialized VM. 1532void os::shutdown() { 1533 1534 // allow PerfMemory to attempt cleanup of any persistent resources 1535 perfMemory_exit(); 1536 1537 // needs to remove object in file system 1538 AttachListener::abort(); 1539 1540 // flush buffered output, finish log files 1541 ostream_abort(); 1542 1543 // Check for abort hook 1544 abort_hook_t abort_hook = Arguments::abort_hook(); 1545 if (abort_hook != NULL) { 1546 abort_hook(); 1547 } 1548 1549} 1550 1551// Note: os::abort() might be called very early during initialization, or 1552// called from signal handler. Before adding something to os::abort(), make 1553// sure it is async-safe and can handle partially initialized VM. 1554void os::abort(bool dump_core) { 1555 os::shutdown(); 1556 if (dump_core) { 1557#ifndef PRODUCT 1558 fdStream out(defaultStream::output_fd()); 1559 out.print_raw("Current thread is "); 1560 char buf[16]; 1561 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1562 out.print_raw_cr(buf); 1563 out.print_raw_cr("Dumping core ..."); 1564#endif 1565 ::abort(); // dump core 1566 } 1567 1568 ::exit(1); 1569} 1570 1571// Die immediately, no exit hook, no abort hook, no cleanup. 1572void os::die() { 1573 // _exit() on LinuxThreads only kills current thread 1574 ::abort(); 1575} 1576 1577// unused on linux for now. 1578void os::set_error_file(const char *logfile) {} 1579 1580 1581// This method is a copy of JDK's sysGetLastErrorString 1582// from src/solaris/hpi/src/system_md.c 1583 1584size_t os::lasterror(char *buf, size_t len) { 1585 1586 if (errno == 0) return 0; 1587 1588 const char *s = ::strerror(errno); 1589 size_t n = ::strlen(s); 1590 if (n >= len) { 1591 n = len - 1; 1592 } 1593 ::strncpy(buf, s, n); 1594 buf[n] = '\0'; 1595 return n; 1596} 1597 1598intx os::current_thread_id() { return (intx)pthread_self(); } 1599int os::current_process_id() { 1600 1601 // Under the old linux thread library, linux gives each thread 1602 // its own process id. Because of this each thread will return 1603 // a different pid if this method were to return the result 1604 // of getpid(2). Linux provides no api that returns the pid 1605 // of the launcher thread for the vm. This implementation 1606 // returns a unique pid, the pid of the launcher thread 1607 // that starts the vm 'process'. 1608 1609 // Under the NPTL, getpid() returns the same pid as the 1610 // launcher thread rather than a unique pid per thread. 1611 // Use gettid() if you want the old pre NPTL behaviour. 1612 1613 // if you are looking for the result of a call to getpid() that 1614 // returns a unique pid for the calling thread, then look at the 1615 // OSThread::thread_id() method in osThread_linux.hpp file 1616 1617 return (int)(_initial_pid ? _initial_pid : getpid()); 1618} 1619 1620// DLL functions 1621 1622const char* os::dll_file_extension() { return ".so"; } 1623 1624// This must be hard coded because it's the system's temporary 1625// directory not the java application's temp directory, ala java.io.tmpdir. 1626const char* os::get_temp_directory() { return "/tmp"; } 1627 1628static bool file_exists(const char* filename) { 1629 struct stat statbuf; 1630 if (filename == NULL || strlen(filename) == 0) { 1631 return false; 1632 } 1633 return os::stat(filename, &statbuf) == 0; 1634} 1635 1636bool os::dll_build_name(char* buffer, size_t buflen, 1637 const char* pname, const char* fname) { 1638 bool retval = false; 1639 // Copied from libhpi 1640 const size_t pnamelen = pname ? strlen(pname) : 0; 1641 1642 // Return error on buffer overflow. 1643 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1644 return retval; 1645 } 1646 1647 if (pnamelen == 0) { 1648 snprintf(buffer, buflen, "lib%s.so", fname); 1649 retval = true; 1650 } else if (strchr(pname, *os::path_separator()) != NULL) { 1651 int n; 1652 char** pelements = split_path(pname, &n); 1653 if (pelements == NULL) { 1654 return false; 1655 } 1656 for (int i = 0 ; i < n ; i++) { 1657 // Really shouldn't be NULL, but check can't hurt 1658 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1659 continue; // skip the empty path values 1660 } 1661 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1662 if (file_exists(buffer)) { 1663 retval = true; 1664 break; 1665 } 1666 } 1667 // release the storage 1668 for (int i = 0 ; i < n ; i++) { 1669 if (pelements[i] != NULL) { 1670 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal); 1671 } 1672 } 1673 if (pelements != NULL) { 1674 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal); 1675 } 1676 } else { 1677 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1678 retval = true; 1679 } 1680 return retval; 1681} 1682 1683// check if addr is inside libjvm.so 1684bool os::address_is_in_vm(address addr) { 1685 static address libjvm_base_addr; 1686 Dl_info dlinfo; 1687 1688 if (libjvm_base_addr == NULL) { 1689 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1690 libjvm_base_addr = (address)dlinfo.dli_fbase; 1691 } 1692 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1693 } 1694 1695 if (dladdr((void *)addr, &dlinfo) != 0) { 1696 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1697 } 1698 1699 return false; 1700} 1701 1702bool os::dll_address_to_function_name(address addr, char *buf, 1703 int buflen, int *offset) { 1704 // buf is not optional, but offset is optional 1705 assert(buf != NULL, "sanity check"); 1706 1707 Dl_info dlinfo; 1708 1709 if (dladdr((void*)addr, &dlinfo) != 0) { 1710 // see if we have a matching symbol 1711 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1712 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1713 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1714 } 1715 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1716 return true; 1717 } 1718 // no matching symbol so try for just file info 1719 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1720 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1721 buf, buflen, offset, dlinfo.dli_fname)) { 1722 return true; 1723 } 1724 } 1725 } 1726 1727 buf[0] = '\0'; 1728 if (offset != NULL) *offset = -1; 1729 return false; 1730} 1731 1732struct _address_to_library_name { 1733 address addr; // input : memory address 1734 size_t buflen; // size of fname 1735 char* fname; // output: library name 1736 address base; // library base addr 1737}; 1738 1739static int address_to_library_name_callback(struct dl_phdr_info *info, 1740 size_t size, void *data) { 1741 int i; 1742 bool found = false; 1743 address libbase = NULL; 1744 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1745 1746 // iterate through all loadable segments 1747 for (i = 0; i < info->dlpi_phnum; i++) { 1748 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1749 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1750 // base address of a library is the lowest address of its loaded 1751 // segments. 1752 if (libbase == NULL || libbase > segbase) { 1753 libbase = segbase; 1754 } 1755 // see if 'addr' is within current segment 1756 if (segbase <= d->addr && 1757 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1758 found = true; 1759 } 1760 } 1761 } 1762 1763 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1764 // so dll_address_to_library_name() can fall through to use dladdr() which 1765 // can figure out executable name from argv[0]. 1766 if (found && info->dlpi_name && info->dlpi_name[0]) { 1767 d->base = libbase; 1768 if (d->fname) { 1769 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1770 } 1771 return 1; 1772 } 1773 return 0; 1774} 1775 1776bool os::dll_address_to_library_name(address addr, char* buf, 1777 int buflen, int* offset) { 1778 // buf is not optional, but offset is optional 1779 assert(buf != NULL, "sanity check"); 1780 1781 Dl_info dlinfo; 1782 struct _address_to_library_name data; 1783 1784 // There is a bug in old glibc dladdr() implementation that it could resolve 1785 // to wrong library name if the .so file has a base address != NULL. Here 1786 // we iterate through the program headers of all loaded libraries to find 1787 // out which library 'addr' really belongs to. This workaround can be 1788 // removed once the minimum requirement for glibc is moved to 2.3.x. 1789 data.addr = addr; 1790 data.fname = buf; 1791 data.buflen = buflen; 1792 data.base = NULL; 1793 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1794 1795 if (rslt) { 1796 // buf already contains library name 1797 if (offset) *offset = addr - data.base; 1798 return true; 1799 } 1800 if (dladdr((void*)addr, &dlinfo) != 0) { 1801 if (dlinfo.dli_fname != NULL) { 1802 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1803 } 1804 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1805 *offset = addr - (address)dlinfo.dli_fbase; 1806 } 1807 return true; 1808 } 1809 1810 buf[0] = '\0'; 1811 if (offset) *offset = -1; 1812 return false; 1813} 1814 1815 // Loads .dll/.so and 1816 // in case of error it checks if .dll/.so was built for the 1817 // same architecture as Hotspot is running on 1818 1819 1820// Remember the stack's state. The Linux dynamic linker will change 1821// the stack to 'executable' at most once, so we must safepoint only once. 1822bool os::Linux::_stack_is_executable = false; 1823 1824// VM operation that loads a library. This is necessary if stack protection 1825// of the Java stacks can be lost during loading the library. If we 1826// do not stop the Java threads, they can stack overflow before the stacks 1827// are protected again. 1828class VM_LinuxDllLoad: public VM_Operation { 1829 private: 1830 const char *_filename; 1831 char *_ebuf; 1832 int _ebuflen; 1833 void *_lib; 1834 public: 1835 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1836 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1837 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1838 void doit() { 1839 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1840 os::Linux::_stack_is_executable = true; 1841 } 1842 void* loaded_library() { return _lib; } 1843}; 1844 1845void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1846{ 1847 void * result = NULL; 1848 bool load_attempted = false; 1849 1850 // Check whether the library to load might change execution rights 1851 // of the stack. If they are changed, the protection of the stack 1852 // guard pages will be lost. We need a safepoint to fix this. 1853 // 1854 // See Linux man page execstack(8) for more info. 1855 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1856 ElfFile ef(filename); 1857 if (!ef.specifies_noexecstack()) { 1858 if (!is_init_completed()) { 1859 os::Linux::_stack_is_executable = true; 1860 // This is OK - No Java threads have been created yet, and hence no 1861 // stack guard pages to fix. 1862 // 1863 // This should happen only when you are building JDK7 using a very 1864 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1865 // 1866 // Dynamic loader will make all stacks executable after 1867 // this function returns, and will not do that again. 1868 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1869 } else { 1870 warning("You have loaded library %s which might have disabled stack guard. " 1871 "The VM will try to fix the stack guard now.\n" 1872 "It's highly recommended that you fix the library with " 1873 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1874 filename); 1875 1876 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1877 JavaThread *jt = JavaThread::current(); 1878 if (jt->thread_state() != _thread_in_native) { 1879 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1880 // that requires ExecStack. Cannot enter safe point. Let's give up. 1881 warning("Unable to fix stack guard. Giving up."); 1882 } else { 1883 if (!LoadExecStackDllInVMThread) { 1884 // This is for the case where the DLL has an static 1885 // constructor function that executes JNI code. We cannot 1886 // load such DLLs in the VMThread. 1887 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1888 } 1889 1890 ThreadInVMfromNative tiv(jt); 1891 debug_only(VMNativeEntryWrapper vew;) 1892 1893 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1894 VMThread::execute(&op); 1895 if (LoadExecStackDllInVMThread) { 1896 result = op.loaded_library(); 1897 } 1898 load_attempted = true; 1899 } 1900 } 1901 } 1902 } 1903 1904 if (!load_attempted) { 1905 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1906 } 1907 1908 if (result != NULL) { 1909 // Successful loading 1910 return result; 1911 } 1912 1913 Elf32_Ehdr elf_head; 1914 int diag_msg_max_length=ebuflen-strlen(ebuf); 1915 char* diag_msg_buf=ebuf+strlen(ebuf); 1916 1917 if (diag_msg_max_length==0) { 1918 // No more space in ebuf for additional diagnostics message 1919 return NULL; 1920 } 1921 1922 1923 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1924 1925 if (file_descriptor < 0) { 1926 // Can't open library, report dlerror() message 1927 return NULL; 1928 } 1929 1930 bool failed_to_read_elf_head= 1931 (sizeof(elf_head)!= 1932 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1933 1934 ::close(file_descriptor); 1935 if (failed_to_read_elf_head) { 1936 // file i/o error - report dlerror() msg 1937 return NULL; 1938 } 1939 1940 typedef struct { 1941 Elf32_Half code; // Actual value as defined in elf.h 1942 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1943 char elf_class; // 32 or 64 bit 1944 char endianess; // MSB or LSB 1945 char* name; // String representation 1946 } arch_t; 1947 1948 #ifndef EM_486 1949 #define EM_486 6 /* Intel 80486 */ 1950 #endif 1951 1952 static const arch_t arch_array[]={ 1953 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1954 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1955 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1956 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1957 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1958 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1959 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1960 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1961 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1962 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1963 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1964 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1965 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1966 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1967 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1968 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1969 }; 1970 1971 #if (defined IA32) 1972 static Elf32_Half running_arch_code=EM_386; 1973 #elif (defined AMD64) 1974 static Elf32_Half running_arch_code=EM_X86_64; 1975 #elif (defined IA64) 1976 static Elf32_Half running_arch_code=EM_IA_64; 1977 #elif (defined __sparc) && (defined _LP64) 1978 static Elf32_Half running_arch_code=EM_SPARCV9; 1979 #elif (defined __sparc) && (!defined _LP64) 1980 static Elf32_Half running_arch_code=EM_SPARC; 1981 #elif (defined __powerpc64__) 1982 static Elf32_Half running_arch_code=EM_PPC64; 1983 #elif (defined __powerpc__) 1984 static Elf32_Half running_arch_code=EM_PPC; 1985 #elif (defined ARM) 1986 static Elf32_Half running_arch_code=EM_ARM; 1987 #elif (defined S390) 1988 static Elf32_Half running_arch_code=EM_S390; 1989 #elif (defined ALPHA) 1990 static Elf32_Half running_arch_code=EM_ALPHA; 1991 #elif (defined MIPSEL) 1992 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1993 #elif (defined PARISC) 1994 static Elf32_Half running_arch_code=EM_PARISC; 1995 #elif (defined MIPS) 1996 static Elf32_Half running_arch_code=EM_MIPS; 1997 #elif (defined M68K) 1998 static Elf32_Half running_arch_code=EM_68K; 1999 #else 2000 #error Method os::dll_load requires that one of following is defined:\ 2001 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 2002 #endif 2003 2004 // Identify compatability class for VM's architecture and library's architecture 2005 // Obtain string descriptions for architectures 2006 2007 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 2008 int running_arch_index=-1; 2009 2010 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 2011 if (running_arch_code == arch_array[i].code) { 2012 running_arch_index = i; 2013 } 2014 if (lib_arch.code == arch_array[i].code) { 2015 lib_arch.compat_class = arch_array[i].compat_class; 2016 lib_arch.name = arch_array[i].name; 2017 } 2018 } 2019 2020 assert(running_arch_index != -1, 2021 "Didn't find running architecture code (running_arch_code) in arch_array"); 2022 if (running_arch_index == -1) { 2023 // Even though running architecture detection failed 2024 // we may still continue with reporting dlerror() message 2025 return NULL; 2026 } 2027 2028 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 2029 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 2030 return NULL; 2031 } 2032 2033#ifndef S390 2034 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 2035 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 2036 return NULL; 2037 } 2038#endif // !S390 2039 2040 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 2041 if ( lib_arch.name!=NULL ) { 2042 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2043 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 2044 lib_arch.name, arch_array[running_arch_index].name); 2045 } else { 2046 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2047 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 2048 lib_arch.code, 2049 arch_array[running_arch_index].name); 2050 } 2051 } 2052 2053 return NULL; 2054} 2055 2056void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) { 2057 void * result = ::dlopen(filename, RTLD_LAZY); 2058 if (result == NULL) { 2059 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2060 ebuf[ebuflen-1] = '\0'; 2061 } 2062 return result; 2063} 2064 2065void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) { 2066 void * result = NULL; 2067 if (LoadExecStackDllInVMThread) { 2068 result = dlopen_helper(filename, ebuf, ebuflen); 2069 } 2070 2071 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2072 // library that requires an executable stack, or which does not have this 2073 // stack attribute set, dlopen changes the stack attribute to executable. The 2074 // read protection of the guard pages gets lost. 2075 // 2076 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2077 // may have been queued at the same time. 2078 2079 if (!_stack_is_executable) { 2080 JavaThread *jt = Threads::first(); 2081 2082 while (jt) { 2083 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2084 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2085 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2086 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2087 warning("Attempt to reguard stack yellow zone failed."); 2088 } 2089 } 2090 jt = jt->next(); 2091 } 2092 } 2093 2094 return result; 2095} 2096 2097/* 2098 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2099 * chances are you might want to run the generated bits against glibc-2.0 2100 * libdl.so, so always use locking for any version of glibc. 2101 */ 2102void* os::dll_lookup(void* handle, const char* name) { 2103 pthread_mutex_lock(&dl_mutex); 2104 void* res = dlsym(handle, name); 2105 pthread_mutex_unlock(&dl_mutex); 2106 return res; 2107} 2108 2109 2110static bool _print_ascii_file(const char* filename, outputStream* st) { 2111 int fd = ::open(filename, O_RDONLY); 2112 if (fd == -1) { 2113 return false; 2114 } 2115 2116 char buf[32]; 2117 int bytes; 2118 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2119 st->print_raw(buf, bytes); 2120 } 2121 2122 ::close(fd); 2123 2124 return true; 2125} 2126 2127void os::print_dll_info(outputStream *st) { 2128 st->print_cr("Dynamic libraries:"); 2129 2130 char fname[32]; 2131 pid_t pid = os::Linux::gettid(); 2132 2133 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2134 2135 if (!_print_ascii_file(fname, st)) { 2136 st->print("Can not get library information for pid = %d\n", pid); 2137 } 2138} 2139 2140void os::print_os_info_brief(outputStream* st) { 2141 os::Linux::print_distro_info(st); 2142 2143 os::Posix::print_uname_info(st); 2144 2145 os::Linux::print_libversion_info(st); 2146 2147} 2148 2149void os::print_os_info(outputStream* st) { 2150 st->print("OS:"); 2151 2152 os::Linux::print_distro_info(st); 2153 2154 os::Posix::print_uname_info(st); 2155 2156 // Print warning if unsafe chroot environment detected 2157 if (unsafe_chroot_detected) { 2158 st->print("WARNING!! "); 2159 st->print_cr(unstable_chroot_error); 2160 } 2161 2162 os::Linux::print_libversion_info(st); 2163 2164 os::Posix::print_rlimit_info(st); 2165 2166 os::Posix::print_load_average(st); 2167 2168 os::Linux::print_full_memory_info(st); 2169} 2170 2171// Try to identify popular distros. 2172// Most Linux distributions have a /etc/XXX-release file, which contains 2173// the OS version string. Newer Linux distributions have a /etc/lsb-release 2174// file that also contains the OS version string. Some have more than one 2175// /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2176// /etc/redhat-release.), so the order is important. 2177// Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2178// their own specific XXX-release file as well as a redhat-release file. 2179// Because of this the XXX-release file needs to be searched for before the 2180// redhat-release file. 2181// Since Red Hat has a lsb-release file that is not very descriptive the 2182// search for redhat-release needs to be before lsb-release. 2183// Since the lsb-release file is the new standard it needs to be searched 2184// before the older style release files. 2185// Searching system-release (Red Hat) and os-release (other Linuxes) are a 2186// next to last resort. The os-release file is a new standard that contains 2187// distribution information and the system-release file seems to be an old 2188// standard that has been replaced by the lsb-release and os-release files. 2189// Searching for the debian_version file is the last resort. It contains 2190// an informative string like "6.0.6" or "wheezy/sid". Because of this 2191// "Debian " is printed before the contents of the debian_version file. 2192void os::Linux::print_distro_info(outputStream* st) { 2193 if (!_print_ascii_file("/etc/oracle-release", st) && 2194 !_print_ascii_file("/etc/mandriva-release", st) && 2195 !_print_ascii_file("/etc/mandrake-release", st) && 2196 !_print_ascii_file("/etc/sun-release", st) && 2197 !_print_ascii_file("/etc/redhat-release", st) && 2198 !_print_ascii_file("/etc/lsb-release", st) && 2199 !_print_ascii_file("/etc/SuSE-release", st) && 2200 !_print_ascii_file("/etc/turbolinux-release", st) && 2201 !_print_ascii_file("/etc/gentoo-release", st) && 2202 !_print_ascii_file("/etc/ltib-release", st) && 2203 !_print_ascii_file("/etc/angstrom-version", st) && 2204 !_print_ascii_file("/etc/system-release", st) && 2205 !_print_ascii_file("/etc/os-release", st)) { 2206 2207 if (file_exists("/etc/debian_version")) { 2208 st->print("Debian "); 2209 _print_ascii_file("/etc/debian_version", st); 2210 } else { 2211 st->print("Linux"); 2212 } 2213 } 2214 st->cr(); 2215} 2216 2217void os::Linux::print_libversion_info(outputStream* st) { 2218 // libc, pthread 2219 st->print("libc:"); 2220 st->print(os::Linux::glibc_version()); st->print(" "); 2221 st->print(os::Linux::libpthread_version()); st->print(" "); 2222 if (os::Linux::is_LinuxThreads()) { 2223 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2224 } 2225 st->cr(); 2226} 2227 2228void os::Linux::print_full_memory_info(outputStream* st) { 2229 st->print("\n/proc/meminfo:\n"); 2230 _print_ascii_file("/proc/meminfo", st); 2231 st->cr(); 2232} 2233 2234void os::print_memory_info(outputStream* st) { 2235 2236 st->print("Memory:"); 2237 st->print(" %dk page", os::vm_page_size()>>10); 2238 2239 // values in struct sysinfo are "unsigned long" 2240 struct sysinfo si; 2241 sysinfo(&si); 2242 2243 st->print(", physical " UINT64_FORMAT "k", 2244 os::physical_memory() >> 10); 2245 st->print("(" UINT64_FORMAT "k free)", 2246 os::available_memory() >> 10); 2247 st->print(", swap " UINT64_FORMAT "k", 2248 ((jlong)si.totalswap * si.mem_unit) >> 10); 2249 st->print("(" UINT64_FORMAT "k free)", 2250 ((jlong)si.freeswap * si.mem_unit) >> 10); 2251 st->cr(); 2252} 2253 2254void os::pd_print_cpu_info(outputStream* st) { 2255 st->print("\n/proc/cpuinfo:\n"); 2256 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2257 st->print(" <Not Available>"); 2258 } 2259 st->cr(); 2260} 2261 2262// Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific 2263// but they're the same for all the linux arch that we support 2264// and they're the same for solaris but there's no common place to put this. 2265const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR", 2266 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG", 2267 "ILL_COPROC", "ILL_BADSTK" }; 2268 2269const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV", 2270 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES", 2271 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" }; 2272 2273const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" }; 2274 2275const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" }; 2276 2277void os::print_siginfo(outputStream* st, void* siginfo) { 2278 st->print("siginfo:"); 2279 2280 const int buflen = 100; 2281 char buf[buflen]; 2282 siginfo_t *si = (siginfo_t*)siginfo; 2283 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen)); 2284 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) { 2285 st->print("si_errno=%s", buf); 2286 } else { 2287 st->print("si_errno=%d", si->si_errno); 2288 } 2289 const int c = si->si_code; 2290 assert(c > 0, "unexpected si_code"); 2291 switch (si->si_signo) { 2292 case SIGILL: 2293 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]); 2294 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2295 break; 2296 case SIGFPE: 2297 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]); 2298 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2299 break; 2300 case SIGSEGV: 2301 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]); 2302 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2303 break; 2304 case SIGBUS: 2305 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]); 2306 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2307 break; 2308 default: 2309 st->print(", si_code=%d", si->si_code); 2310 // no si_addr 2311 } 2312 2313 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2314 UseSharedSpaces) { 2315 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2316 if (mapinfo->is_in_shared_space(si->si_addr)) { 2317 st->print("\n\nError accessing class data sharing archive." \ 2318 " Mapped file inaccessible during execution, " \ 2319 " possible disk/network problem."); 2320 } 2321 } 2322 st->cr(); 2323} 2324 2325 2326static void print_signal_handler(outputStream* st, int sig, 2327 char* buf, size_t buflen); 2328 2329void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2330 st->print_cr("Signal Handlers:"); 2331 print_signal_handler(st, SIGSEGV, buf, buflen); 2332 print_signal_handler(st, SIGBUS , buf, buflen); 2333 print_signal_handler(st, SIGFPE , buf, buflen); 2334 print_signal_handler(st, SIGPIPE, buf, buflen); 2335 print_signal_handler(st, SIGXFSZ, buf, buflen); 2336 print_signal_handler(st, SIGILL , buf, buflen); 2337 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2338 print_signal_handler(st, SR_signum, buf, buflen); 2339 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2340 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2341 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2342 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2343} 2344 2345static char saved_jvm_path[MAXPATHLEN] = {0}; 2346 2347// Find the full path to the current module, libjvm.so 2348void os::jvm_path(char *buf, jint buflen) { 2349 // Error checking. 2350 if (buflen < MAXPATHLEN) { 2351 assert(false, "must use a large-enough buffer"); 2352 buf[0] = '\0'; 2353 return; 2354 } 2355 // Lazy resolve the path to current module. 2356 if (saved_jvm_path[0] != 0) { 2357 strcpy(buf, saved_jvm_path); 2358 return; 2359 } 2360 2361 char dli_fname[MAXPATHLEN]; 2362 bool ret = dll_address_to_library_name( 2363 CAST_FROM_FN_PTR(address, os::jvm_path), 2364 dli_fname, sizeof(dli_fname), NULL); 2365 assert(ret, "cannot locate libjvm"); 2366 char *rp = NULL; 2367 if (ret && dli_fname[0] != '\0') { 2368 rp = realpath(dli_fname, buf); 2369 } 2370 if (rp == NULL) 2371 return; 2372 2373 if (Arguments::created_by_gamma_launcher()) { 2374 // Support for the gamma launcher. Typical value for buf is 2375 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at 2376 // the right place in the string, then assume we are installed in a JDK and 2377 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix 2378 // up the path so it looks like libjvm.so is installed there (append a 2379 // fake suffix hotspot/libjvm.so). 2380 const char *p = buf + strlen(buf) - 1; 2381 for (int count = 0; p > buf && count < 5; ++count) { 2382 for (--p; p > buf && *p != '/'; --p) 2383 /* empty */ ; 2384 } 2385 2386 if (strncmp(p, "/jre/lib/", 9) != 0) { 2387 // Look for JAVA_HOME in the environment. 2388 char* java_home_var = ::getenv("JAVA_HOME"); 2389 if (java_home_var != NULL && java_home_var[0] != 0) { 2390 char* jrelib_p; 2391 int len; 2392 2393 // Check the current module name "libjvm.so". 2394 p = strrchr(buf, '/'); 2395 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2396 2397 rp = realpath(java_home_var, buf); 2398 if (rp == NULL) 2399 return; 2400 2401 // determine if this is a legacy image or modules image 2402 // modules image doesn't have "jre" subdirectory 2403 len = strlen(buf); 2404 jrelib_p = buf + len; 2405 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2406 if (0 != access(buf, F_OK)) { 2407 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2408 } 2409 2410 if (0 == access(buf, F_OK)) { 2411 // Use current module name "libjvm.so" 2412 len = strlen(buf); 2413 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2414 } else { 2415 // Go back to path of .so 2416 rp = realpath(dli_fname, buf); 2417 if (rp == NULL) 2418 return; 2419 } 2420 } 2421 } 2422 } 2423 2424 strcpy(saved_jvm_path, buf); 2425} 2426 2427void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2428 // no prefix required, not even "_" 2429} 2430 2431void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2432 // no suffix required 2433} 2434 2435//////////////////////////////////////////////////////////////////////////////// 2436// sun.misc.Signal support 2437 2438static volatile jint sigint_count = 0; 2439 2440static void 2441UserHandler(int sig, void *siginfo, void *context) { 2442 // 4511530 - sem_post is serialized and handled by the manager thread. When 2443 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2444 // don't want to flood the manager thread with sem_post requests. 2445 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2446 return; 2447 2448 // Ctrl-C is pressed during error reporting, likely because the error 2449 // handler fails to abort. Let VM die immediately. 2450 if (sig == SIGINT && is_error_reported()) { 2451 os::die(); 2452 } 2453 2454 os::signal_notify(sig); 2455} 2456 2457void* os::user_handler() { 2458 return CAST_FROM_FN_PTR(void*, UserHandler); 2459} 2460 2461class Semaphore : public StackObj { 2462 public: 2463 Semaphore(); 2464 ~Semaphore(); 2465 void signal(); 2466 void wait(); 2467 bool trywait(); 2468 bool timedwait(unsigned int sec, int nsec); 2469 private: 2470 sem_t _semaphore; 2471}; 2472 2473 2474Semaphore::Semaphore() { 2475 sem_init(&_semaphore, 0, 0); 2476} 2477 2478Semaphore::~Semaphore() { 2479 sem_destroy(&_semaphore); 2480} 2481 2482void Semaphore::signal() { 2483 sem_post(&_semaphore); 2484} 2485 2486void Semaphore::wait() { 2487 sem_wait(&_semaphore); 2488} 2489 2490bool Semaphore::trywait() { 2491 return sem_trywait(&_semaphore) == 0; 2492} 2493 2494bool Semaphore::timedwait(unsigned int sec, int nsec) { 2495 struct timespec ts; 2496 unpackTime(&ts, false, (sec * NANOSECS_PER_SEC) + nsec); 2497 2498 while (1) { 2499 int result = sem_timedwait(&_semaphore, &ts); 2500 if (result == 0) { 2501 return true; 2502 } else if (errno == EINTR) { 2503 continue; 2504 } else if (errno == ETIMEDOUT) { 2505 return false; 2506 } else { 2507 return false; 2508 } 2509 } 2510} 2511 2512extern "C" { 2513 typedef void (*sa_handler_t)(int); 2514 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2515} 2516 2517void* os::signal(int signal_number, void* handler) { 2518 struct sigaction sigAct, oldSigAct; 2519 2520 sigfillset(&(sigAct.sa_mask)); 2521 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2522 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2523 2524 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2525 // -1 means registration failed 2526 return (void *)-1; 2527 } 2528 2529 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2530} 2531 2532void os::signal_raise(int signal_number) { 2533 ::raise(signal_number); 2534} 2535 2536/* 2537 * The following code is moved from os.cpp for making this 2538 * code platform specific, which it is by its very nature. 2539 */ 2540 2541// Will be modified when max signal is changed to be dynamic 2542int os::sigexitnum_pd() { 2543 return NSIG; 2544} 2545 2546// a counter for each possible signal value 2547static volatile jint pending_signals[NSIG+1] = { 0 }; 2548 2549// Linux(POSIX) specific hand shaking semaphore. 2550static sem_t sig_sem; 2551static Semaphore sr_semaphore; 2552 2553void os::signal_init_pd() { 2554 // Initialize signal structures 2555 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2556 2557 // Initialize signal semaphore 2558 ::sem_init(&sig_sem, 0, 0); 2559} 2560 2561void os::signal_notify(int sig) { 2562 Atomic::inc(&pending_signals[sig]); 2563 ::sem_post(&sig_sem); 2564} 2565 2566static int check_pending_signals(bool wait) { 2567 Atomic::store(0, &sigint_count); 2568 for (;;) { 2569 for (int i = 0; i < NSIG + 1; i++) { 2570 jint n = pending_signals[i]; 2571 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2572 return i; 2573 } 2574 } 2575 if (!wait) { 2576 return -1; 2577 } 2578 JavaThread *thread = JavaThread::current(); 2579 ThreadBlockInVM tbivm(thread); 2580 2581 bool threadIsSuspended; 2582 do { 2583 thread->set_suspend_equivalent(); 2584 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2585 ::sem_wait(&sig_sem); 2586 2587 // were we externally suspended while we were waiting? 2588 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2589 if (threadIsSuspended) { 2590 // 2591 // The semaphore has been incremented, but while we were waiting 2592 // another thread suspended us. We don't want to continue running 2593 // while suspended because that would surprise the thread that 2594 // suspended us. 2595 // 2596 ::sem_post(&sig_sem); 2597 2598 thread->java_suspend_self(); 2599 } 2600 } while (threadIsSuspended); 2601 } 2602} 2603 2604int os::signal_lookup() { 2605 return check_pending_signals(false); 2606} 2607 2608int os::signal_wait() { 2609 return check_pending_signals(true); 2610} 2611 2612//////////////////////////////////////////////////////////////////////////////// 2613// Virtual Memory 2614 2615int os::vm_page_size() { 2616 // Seems redundant as all get out 2617 assert(os::Linux::page_size() != -1, "must call os::init"); 2618 return os::Linux::page_size(); 2619} 2620 2621// Solaris allocates memory by pages. 2622int os::vm_allocation_granularity() { 2623 assert(os::Linux::page_size() != -1, "must call os::init"); 2624 return os::Linux::page_size(); 2625} 2626 2627// Rationale behind this function: 2628// current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2629// mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2630// samples for JITted code. Here we create private executable mapping over the code cache 2631// and then we can use standard (well, almost, as mapping can change) way to provide 2632// info for the reporting script by storing timestamp and location of symbol 2633void linux_wrap_code(char* base, size_t size) { 2634 static volatile jint cnt = 0; 2635 2636 if (!UseOprofile) { 2637 return; 2638 } 2639 2640 char buf[PATH_MAX+1]; 2641 int num = Atomic::add(1, &cnt); 2642 2643 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2644 os::get_temp_directory(), os::current_process_id(), num); 2645 unlink(buf); 2646 2647 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2648 2649 if (fd != -1) { 2650 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2651 if (rv != (off_t)-1) { 2652 if (::write(fd, "", 1) == 1) { 2653 mmap(base, size, 2654 PROT_READ|PROT_WRITE|PROT_EXEC, 2655 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2656 } 2657 } 2658 ::close(fd); 2659 unlink(buf); 2660 } 2661} 2662 2663static bool recoverable_mmap_error(int err) { 2664 // See if the error is one we can let the caller handle. This 2665 // list of errno values comes from JBS-6843484. I can't find a 2666 // Linux man page that documents this specific set of errno 2667 // values so while this list currently matches Solaris, it may 2668 // change as we gain experience with this failure mode. 2669 switch (err) { 2670 case EBADF: 2671 case EINVAL: 2672 case ENOTSUP: 2673 // let the caller deal with these errors 2674 return true; 2675 2676 default: 2677 // Any remaining errors on this OS can cause our reserved mapping 2678 // to be lost. That can cause confusion where different data 2679 // structures think they have the same memory mapped. The worst 2680 // scenario is if both the VM and a library think they have the 2681 // same memory mapped. 2682 return false; 2683 } 2684} 2685 2686static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2687 int err) { 2688 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2689 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2690 strerror(err), err); 2691} 2692 2693static void warn_fail_commit_memory(char* addr, size_t size, 2694 size_t alignment_hint, bool exec, 2695 int err) { 2696 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2697 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2698 alignment_hint, exec, strerror(err), err); 2699} 2700 2701// NOTE: Linux kernel does not really reserve the pages for us. 2702// All it does is to check if there are enough free pages 2703// left at the time of mmap(). This could be a potential 2704// problem. 2705int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2706 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2707 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2708 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2709 if (res != (uintptr_t) MAP_FAILED) { 2710 if (UseNUMAInterleaving) { 2711 numa_make_global(addr, size); 2712 } 2713 return 0; 2714 } 2715 2716 int err = errno; // save errno from mmap() call above 2717 2718 if (!recoverable_mmap_error(err)) { 2719 warn_fail_commit_memory(addr, size, exec, err); 2720 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2721 } 2722 2723 return err; 2724} 2725 2726bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2727 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2728} 2729 2730void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2731 const char* mesg) { 2732 assert(mesg != NULL, "mesg must be specified"); 2733 int err = os::Linux::commit_memory_impl(addr, size, exec); 2734 if (err != 0) { 2735 // the caller wants all commit errors to exit with the specified mesg: 2736 warn_fail_commit_memory(addr, size, exec, err); 2737 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2738 } 2739} 2740 2741// Define MAP_HUGETLB here so we can build HotSpot on old systems. 2742#ifndef MAP_HUGETLB 2743#define MAP_HUGETLB 0x40000 2744#endif 2745 2746// Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2747#ifndef MADV_HUGEPAGE 2748#define MADV_HUGEPAGE 14 2749#endif 2750 2751int os::Linux::commit_memory_impl(char* addr, size_t size, 2752 size_t alignment_hint, bool exec) { 2753 int err = os::Linux::commit_memory_impl(addr, size, exec); 2754 if (err == 0) { 2755 realign_memory(addr, size, alignment_hint); 2756 } 2757 return err; 2758} 2759 2760bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2761 bool exec) { 2762 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2763} 2764 2765void os::pd_commit_memory_or_exit(char* addr, size_t size, 2766 size_t alignment_hint, bool exec, 2767 const char* mesg) { 2768 assert(mesg != NULL, "mesg must be specified"); 2769 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2770 if (err != 0) { 2771 // the caller wants all commit errors to exit with the specified mesg: 2772 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2773 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2774 } 2775} 2776 2777void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2778 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2779 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2780 // be supported or the memory may already be backed by huge pages. 2781 ::madvise(addr, bytes, MADV_HUGEPAGE); 2782 } 2783} 2784 2785void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2786 // This method works by doing an mmap over an existing mmaping and effectively discarding 2787 // the existing pages. However it won't work for SHM-based large pages that cannot be 2788 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2789 // small pages on top of the SHM segment. This method always works for small pages, so we 2790 // allow that in any case. 2791 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2792 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2793 } 2794} 2795 2796void os::numa_make_global(char *addr, size_t bytes) { 2797 Linux::numa_interleave_memory(addr, bytes); 2798} 2799 2800// Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2801// bind policy to MPOL_PREFERRED for the current thread. 2802#define USE_MPOL_PREFERRED 0 2803 2804void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2805 // To make NUMA and large pages more robust when both enabled, we need to ease 2806 // the requirements on where the memory should be allocated. MPOL_BIND is the 2807 // default policy and it will force memory to be allocated on the specified 2808 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2809 // the specified node, but will not force it. Using this policy will prevent 2810 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2811 // free large pages. 2812 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2813 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2814} 2815 2816bool os::numa_topology_changed() { return false; } 2817 2818size_t os::numa_get_groups_num() { 2819 int max_node = Linux::numa_max_node(); 2820 return max_node > 0 ? max_node + 1 : 1; 2821} 2822 2823int os::numa_get_group_id() { 2824 int cpu_id = Linux::sched_getcpu(); 2825 if (cpu_id != -1) { 2826 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2827 if (lgrp_id != -1) { 2828 return lgrp_id; 2829 } 2830 } 2831 return 0; 2832} 2833 2834size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2835 for (size_t i = 0; i < size; i++) { 2836 ids[i] = i; 2837 } 2838 return size; 2839} 2840 2841bool os::get_page_info(char *start, page_info* info) { 2842 return false; 2843} 2844 2845char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2846 return end; 2847} 2848 2849 2850int os::Linux::sched_getcpu_syscall(void) { 2851 unsigned int cpu; 2852 int retval = -1; 2853 2854#if defined(IA32) 2855# ifndef SYS_getcpu 2856# define SYS_getcpu 318 2857# endif 2858 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2859#elif defined(AMD64) 2860// Unfortunately we have to bring all these macros here from vsyscall.h 2861// to be able to compile on old linuxes. 2862# define __NR_vgetcpu 2 2863# define VSYSCALL_START (-10UL << 20) 2864# define VSYSCALL_SIZE 1024 2865# define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2866 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2867 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2868 retval = vgetcpu(&cpu, NULL, NULL); 2869#endif 2870 2871 return (retval == -1) ? retval : cpu; 2872} 2873 2874// Something to do with the numa-aware allocator needs these symbols 2875extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2876extern "C" JNIEXPORT void numa_error(char *where) { } 2877extern "C" JNIEXPORT int fork1() { return fork(); } 2878 2879 2880// If we are running with libnuma version > 2, then we should 2881// be trying to use symbols with versions 1.1 2882// If we are running with earlier version, which did not have symbol versions, 2883// we should use the base version. 2884void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2885 void *f = dlvsym(handle, name, "libnuma_1.1"); 2886 if (f == NULL) { 2887 f = dlsym(handle, name); 2888 } 2889 return f; 2890} 2891 2892bool os::Linux::libnuma_init() { 2893 // sched_getcpu() should be in libc. 2894 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2895 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2896 2897 // If it's not, try a direct syscall. 2898 if (sched_getcpu() == -1) 2899 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall)); 2900 2901 if (sched_getcpu() != -1) { // Does it work? 2902 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2903 if (handle != NULL) { 2904 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2905 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2906 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2907 libnuma_dlsym(handle, "numa_max_node"))); 2908 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2909 libnuma_dlsym(handle, "numa_available"))); 2910 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2911 libnuma_dlsym(handle, "numa_tonode_memory"))); 2912 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2913 libnuma_dlsym(handle, "numa_interleave_memory"))); 2914 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2915 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2916 2917 2918 if (numa_available() != -1) { 2919 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2920 // Create a cpu -> node mapping 2921 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2922 rebuild_cpu_to_node_map(); 2923 return true; 2924 } 2925 } 2926 } 2927 return false; 2928} 2929 2930// rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2931// The table is later used in get_node_by_cpu(). 2932void os::Linux::rebuild_cpu_to_node_map() { 2933 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2934 // in libnuma (possible values are starting from 16, 2935 // and continuing up with every other power of 2, but less 2936 // than the maximum number of CPUs supported by kernel), and 2937 // is a subject to change (in libnuma version 2 the requirements 2938 // are more reasonable) we'll just hardcode the number they use 2939 // in the library. 2940 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2941 2942 size_t cpu_num = os::active_processor_count(); 2943 size_t cpu_map_size = NCPUS / BitsPerCLong; 2944 size_t cpu_map_valid_size = 2945 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2946 2947 cpu_to_node()->clear(); 2948 cpu_to_node()->at_grow(cpu_num - 1); 2949 size_t node_num = numa_get_groups_num(); 2950 2951 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2952 for (size_t i = 0; i < node_num; i++) { 2953 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2954 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2955 if (cpu_map[j] != 0) { 2956 for (size_t k = 0; k < BitsPerCLong; k++) { 2957 if (cpu_map[j] & (1UL << k)) { 2958 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2959 } 2960 } 2961 } 2962 } 2963 } 2964 } 2965 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal); 2966} 2967 2968int os::Linux::get_node_by_cpu(int cpu_id) { 2969 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2970 return cpu_to_node()->at(cpu_id); 2971 } 2972 return -1; 2973} 2974 2975GrowableArray<int>* os::Linux::_cpu_to_node; 2976os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2977os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2978os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2979os::Linux::numa_available_func_t os::Linux::_numa_available; 2980os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2981os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2982os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2983unsigned long* os::Linux::_numa_all_nodes; 2984 2985bool os::pd_uncommit_memory(char* addr, size_t size) { 2986 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2987 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2988 return res != (uintptr_t) MAP_FAILED; 2989} 2990 2991static 2992address get_stack_commited_bottom(address bottom, size_t size) { 2993 address nbot = bottom; 2994 address ntop = bottom + size; 2995 2996 size_t page_sz = os::vm_page_size(); 2997 unsigned pages = size / page_sz; 2998 2999 unsigned char vec[1]; 3000 unsigned imin = 1, imax = pages + 1, imid; 3001 int mincore_return_value; 3002 3003 while (imin < imax) { 3004 imid = (imax + imin) / 2; 3005 nbot = ntop - (imid * page_sz); 3006 3007 // Use a trick with mincore to check whether the page is mapped or not. 3008 // mincore sets vec to 1 if page resides in memory and to 0 if page 3009 // is swapped output but if page we are asking for is unmapped 3010 // it returns -1,ENOMEM 3011 mincore_return_value = mincore(nbot, page_sz, vec); 3012 3013 if (mincore_return_value == -1) { 3014 // Page is not mapped go up 3015 // to find first mapped page 3016 if (errno != EAGAIN) { 3017 assert(errno == ENOMEM, "Unexpected mincore errno"); 3018 imax = imid; 3019 } 3020 } else { 3021 // Page is mapped go down 3022 // to find first not mapped page 3023 imin = imid + 1; 3024 } 3025 } 3026 3027 nbot = nbot + page_sz; 3028 3029 // Adjust stack bottom one page up if last checked page is not mapped 3030 if (mincore_return_value == -1) { 3031 nbot = nbot + page_sz; 3032 } 3033 3034 return nbot; 3035} 3036 3037 3038// Linux uses a growable mapping for the stack, and if the mapping for 3039// the stack guard pages is not removed when we detach a thread the 3040// stack cannot grow beyond the pages where the stack guard was 3041// mapped. If at some point later in the process the stack expands to 3042// that point, the Linux kernel cannot expand the stack any further 3043// because the guard pages are in the way, and a segfault occurs. 3044// 3045// However, it's essential not to split the stack region by unmapping 3046// a region (leaving a hole) that's already part of the stack mapping, 3047// so if the stack mapping has already grown beyond the guard pages at 3048// the time we create them, we have to truncate the stack mapping. 3049// So, we need to know the extent of the stack mapping when 3050// create_stack_guard_pages() is called. 3051 3052// We only need this for stacks that are growable: at the time of 3053// writing thread stacks don't use growable mappings (i.e. those 3054// creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 3055// only applies to the main thread. 3056 3057// If the (growable) stack mapping already extends beyond the point 3058// where we're going to put our guard pages, truncate the mapping at 3059// that point by munmap()ping it. This ensures that when we later 3060// munmap() the guard pages we don't leave a hole in the stack 3061// mapping. This only affects the main/initial thread 3062 3063bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3064 3065 if (os::Linux::is_initial_thread()) { 3066 // As we manually grow stack up to bottom inside create_attached_thread(), 3067 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3068 // we don't need to do anything special. 3069 // Check it first, before calling heavy function. 3070 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3071 unsigned char vec[1]; 3072 3073 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3074 // Fallback to slow path on all errors, including EAGAIN 3075 stack_extent = (uintptr_t) get_stack_commited_bottom( 3076 os::Linux::initial_thread_stack_bottom(), 3077 (size_t)addr - stack_extent); 3078 } 3079 3080 if (stack_extent < (uintptr_t)addr) { 3081 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3082 } 3083 } 3084 3085 return os::commit_memory(addr, size, !ExecMem); 3086} 3087 3088// If this is a growable mapping, remove the guard pages entirely by 3089// munmap()ping them. If not, just call uncommit_memory(). This only 3090// affects the main/initial thread, but guard against future OS changes 3091// It's safe to always unmap guard pages for initial thread because we 3092// always place it right after end of the mapped region 3093 3094bool os::remove_stack_guard_pages(char* addr, size_t size) { 3095 uintptr_t stack_extent, stack_base; 3096 3097 if (os::Linux::is_initial_thread()) { 3098 return ::munmap(addr, size) == 0; 3099 } 3100 3101 return os::uncommit_memory(addr, size); 3102} 3103 3104static address _highest_vm_reserved_address = NULL; 3105 3106// If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3107// at 'requested_addr'. If there are existing memory mappings at the same 3108// location, however, they will be overwritten. If 'fixed' is false, 3109// 'requested_addr' is only treated as a hint, the return value may or 3110// may not start from the requested address. Unlike Linux mmap(), this 3111// function returns NULL to indicate failure. 3112static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3113 char * addr; 3114 int flags; 3115 3116 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3117 if (fixed) { 3118 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3119 flags |= MAP_FIXED; 3120 } 3121 3122 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3123 // touch an uncommitted page. Otherwise, the read/write might 3124 // succeed if we have enough swap space to back the physical page. 3125 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3126 flags, -1, 0); 3127 3128 if (addr != MAP_FAILED) { 3129 // anon_mmap() should only get called during VM initialization, 3130 // don't need lock (actually we can skip locking even it can be called 3131 // from multiple threads, because _highest_vm_reserved_address is just a 3132 // hint about the upper limit of non-stack memory regions.) 3133 if ((address)addr + bytes > _highest_vm_reserved_address) { 3134 _highest_vm_reserved_address = (address)addr + bytes; 3135 } 3136 } 3137 3138 return addr == MAP_FAILED ? NULL : addr; 3139} 3140 3141// Don't update _highest_vm_reserved_address, because there might be memory 3142// regions above addr + size. If so, releasing a memory region only creates 3143// a hole in the address space, it doesn't help prevent heap-stack collision. 3144// 3145static int anon_munmap(char * addr, size_t size) { 3146 return ::munmap(addr, size) == 0; 3147} 3148 3149char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3150 size_t alignment_hint) { 3151 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3152} 3153 3154bool os::pd_release_memory(char* addr, size_t size) { 3155 return anon_munmap(addr, size); 3156} 3157 3158static address highest_vm_reserved_address() { 3159 return _highest_vm_reserved_address; 3160} 3161 3162static bool linux_mprotect(char* addr, size_t size, int prot) { 3163 // Linux wants the mprotect address argument to be page aligned. 3164 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3165 3166 // According to SUSv3, mprotect() should only be used with mappings 3167 // established by mmap(), and mmap() always maps whole pages. Unaligned 3168 // 'addr' likely indicates problem in the VM (e.g. trying to change 3169 // protection of malloc'ed or statically allocated memory). Check the 3170 // caller if you hit this assert. 3171 assert(addr == bottom, "sanity check"); 3172 3173 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3174 return ::mprotect(bottom, size, prot) == 0; 3175} 3176 3177// Set protections specified 3178bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3179 bool is_committed) { 3180 unsigned int p = 0; 3181 switch (prot) { 3182 case MEM_PROT_NONE: p = PROT_NONE; break; 3183 case MEM_PROT_READ: p = PROT_READ; break; 3184 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3185 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3186 default: 3187 ShouldNotReachHere(); 3188 } 3189 // is_committed is unused. 3190 return linux_mprotect(addr, bytes, p); 3191} 3192 3193bool os::guard_memory(char* addr, size_t size) { 3194 return linux_mprotect(addr, size, PROT_NONE); 3195} 3196 3197bool os::unguard_memory(char* addr, size_t size) { 3198 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3199} 3200 3201bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) { 3202 bool result = false; 3203 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3204 MAP_ANONYMOUS|MAP_PRIVATE, 3205 -1, 0); 3206 if (p != MAP_FAILED) { 3207 void *aligned_p = align_ptr_up(p, page_size); 3208 3209 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3210 3211 munmap(p, page_size * 2); 3212 } 3213 3214 if (warn && !result) { 3215 warning("TransparentHugePages is not supported by the operating system."); 3216 } 3217 3218 return result; 3219} 3220 3221bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3222 bool result = false; 3223 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3224 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3225 -1, 0); 3226 3227 if (p != MAP_FAILED) { 3228 // We don't know if this really is a huge page or not. 3229 FILE *fp = fopen("/proc/self/maps", "r"); 3230 if (fp) { 3231 while (!feof(fp)) { 3232 char chars[257]; 3233 long x = 0; 3234 if (fgets(chars, sizeof(chars), fp)) { 3235 if (sscanf(chars, "%lx-%*x", &x) == 1 3236 && x == (long)p) { 3237 if (strstr (chars, "hugepage")) { 3238 result = true; 3239 break; 3240 } 3241 } 3242 } 3243 } 3244 fclose(fp); 3245 } 3246 munmap(p, page_size); 3247 } 3248 3249 if (warn && !result) { 3250 warning("HugeTLBFS is not supported by the operating system."); 3251 } 3252 3253 return result; 3254} 3255 3256/* 3257* Set the coredump_filter bits to include largepages in core dump (bit 6) 3258* 3259* From the coredump_filter documentation: 3260* 3261* - (bit 0) anonymous private memory 3262* - (bit 1) anonymous shared memory 3263* - (bit 2) file-backed private memory 3264* - (bit 3) file-backed shared memory 3265* - (bit 4) ELF header pages in file-backed private memory areas (it is 3266* effective only if the bit 2 is cleared) 3267* - (bit 5) hugetlb private memory 3268* - (bit 6) hugetlb shared memory 3269*/ 3270static void set_coredump_filter(void) { 3271 FILE *f; 3272 long cdm; 3273 3274 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3275 return; 3276 } 3277 3278 if (fscanf(f, "%lx", &cdm) != 1) { 3279 fclose(f); 3280 return; 3281 } 3282 3283 rewind(f); 3284 3285 if ((cdm & LARGEPAGES_BIT) == 0) { 3286 cdm |= LARGEPAGES_BIT; 3287 fprintf(f, "%#lx", cdm); 3288 } 3289 3290 fclose(f); 3291} 3292 3293// Large page support 3294 3295static size_t _large_page_size = 0; 3296 3297size_t os::Linux::find_large_page_size() { 3298 size_t large_page_size = 0; 3299 3300 // large_page_size on Linux is used to round up heap size. x86 uses either 3301 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3302 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3303 // page as large as 256M. 3304 // 3305 // Here we try to figure out page size by parsing /proc/meminfo and looking 3306 // for a line with the following format: 3307 // Hugepagesize: 2048 kB 3308 // 3309 // If we can't determine the value (e.g. /proc is not mounted, or the text 3310 // format has been changed), we'll use the largest page size supported by 3311 // the processor. 3312 3313#ifndef ZERO 3314 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3315 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3316#endif // ZERO 3317 3318 FILE *fp = fopen("/proc/meminfo", "r"); 3319 if (fp) { 3320 while (!feof(fp)) { 3321 int x = 0; 3322 char buf[16]; 3323 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3324 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3325 large_page_size = x * K; 3326 break; 3327 } 3328 } else { 3329 // skip to next line 3330 for (;;) { 3331 int ch = fgetc(fp); 3332 if (ch == EOF || ch == (int)'\n') break; 3333 } 3334 } 3335 } 3336 fclose(fp); 3337 } 3338 3339 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3340 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3341 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3342 proper_unit_for_byte_size(large_page_size)); 3343 } 3344 3345 return large_page_size; 3346} 3347 3348size_t os::Linux::setup_large_page_size() { 3349 _large_page_size = Linux::find_large_page_size(); 3350 const size_t default_page_size = (size_t)Linux::page_size(); 3351 if (_large_page_size > default_page_size) { 3352 _page_sizes[0] = _large_page_size; 3353 _page_sizes[1] = default_page_size; 3354 _page_sizes[2] = 0; 3355 } 3356 3357 return _large_page_size; 3358} 3359 3360bool os::Linux::setup_large_page_type(size_t page_size) { 3361 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3362 FLAG_IS_DEFAULT(UseSHM) && 3363 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3364 3365 // The type of large pages has not been specified by the user. 3366 3367 // Try UseHugeTLBFS and then UseSHM. 3368 UseHugeTLBFS = UseSHM = true; 3369 3370 // Don't try UseTransparentHugePages since there are known 3371 // performance issues with it turned on. This might change in the future. 3372 UseTransparentHugePages = false; 3373 } 3374 3375 if (UseTransparentHugePages) { 3376 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3377 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3378 UseHugeTLBFS = false; 3379 UseSHM = false; 3380 return true; 3381 } 3382 UseTransparentHugePages = false; 3383 } 3384 3385 if (UseHugeTLBFS) { 3386 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3387 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3388 UseSHM = false; 3389 return true; 3390 } 3391 UseHugeTLBFS = false; 3392 } 3393 3394 return UseSHM; 3395} 3396 3397void os::large_page_init() { 3398 if (!UseLargePages && 3399 !UseTransparentHugePages && 3400 !UseHugeTLBFS && 3401 !UseSHM) { 3402 // Not using large pages. 3403 return; 3404 } 3405 3406 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3407 // The user explicitly turned off large pages. 3408 // Ignore the rest of the large pages flags. 3409 UseTransparentHugePages = false; 3410 UseHugeTLBFS = false; 3411 UseSHM = false; 3412 return; 3413 } 3414 3415 size_t large_page_size = Linux::setup_large_page_size(); 3416 UseLargePages = Linux::setup_large_page_type(large_page_size); 3417 3418 set_coredump_filter(); 3419} 3420 3421#ifndef SHM_HUGETLB 3422#define SHM_HUGETLB 04000 3423#endif 3424 3425char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3426 // "exec" is passed in but not used. Creating the shared image for 3427 // the code cache doesn't have an SHM_X executable permission to check. 3428 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3429 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3430 3431 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3432 return NULL; // Fallback to small pages. 3433 } 3434 3435 key_t key = IPC_PRIVATE; 3436 char *addr; 3437 3438 bool warn_on_failure = UseLargePages && 3439 (!FLAG_IS_DEFAULT(UseLargePages) || 3440 !FLAG_IS_DEFAULT(UseSHM) || 3441 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 3442 ); 3443 char msg[128]; 3444 3445 // Create a large shared memory region to attach to based on size. 3446 // Currently, size is the total size of the heap 3447 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3448 if (shmid == -1) { 3449 // Possible reasons for shmget failure: 3450 // 1. shmmax is too small for Java heap. 3451 // > check shmmax value: cat /proc/sys/kernel/shmmax 3452 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3453 // 2. not enough large page memory. 3454 // > check available large pages: cat /proc/meminfo 3455 // > increase amount of large pages: 3456 // echo new_value > /proc/sys/vm/nr_hugepages 3457 // Note 1: different Linux may use different name for this property, 3458 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3459 // Note 2: it's possible there's enough physical memory available but 3460 // they are so fragmented after a long run that they can't 3461 // coalesce into large pages. Try to reserve large pages when 3462 // the system is still "fresh". 3463 if (warn_on_failure) { 3464 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3465 warning(msg); 3466 } 3467 return NULL; 3468 } 3469 3470 // attach to the region 3471 addr = (char*)shmat(shmid, req_addr, 0); 3472 int err = errno; 3473 3474 // Remove shmid. If shmat() is successful, the actual shared memory segment 3475 // will be deleted when it's detached by shmdt() or when the process 3476 // terminates. If shmat() is not successful this will remove the shared 3477 // segment immediately. 3478 shmctl(shmid, IPC_RMID, NULL); 3479 3480 if ((intptr_t)addr == -1) { 3481 if (warn_on_failure) { 3482 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3483 warning(msg); 3484 } 3485 return NULL; 3486 } 3487 3488 return addr; 3489} 3490 3491static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) { 3492 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3493 3494 bool warn_on_failure = UseLargePages && 3495 (!FLAG_IS_DEFAULT(UseLargePages) || 3496 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3497 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3498 3499 if (warn_on_failure) { 3500 char msg[128]; 3501 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3502 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3503 warning(msg); 3504 } 3505} 3506 3507char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) { 3508 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3509 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3510 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3511 3512 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3513 char* addr = (char*)::mmap(req_addr, bytes, prot, 3514 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3515 -1, 0); 3516 3517 if (addr == MAP_FAILED) { 3518 warn_on_large_pages_failure(req_addr, bytes, errno); 3519 return NULL; 3520 } 3521 3522 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3523 3524 return addr; 3525} 3526 3527char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3528 size_t large_page_size = os::large_page_size(); 3529 3530 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3531 3532 // Allocate small pages. 3533 3534 char* start; 3535 if (req_addr != NULL) { 3536 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3537 assert(is_size_aligned(bytes, alignment), "Must be"); 3538 start = os::reserve_memory(bytes, req_addr); 3539 assert(start == NULL || start == req_addr, "Must be"); 3540 } else { 3541 start = os::reserve_memory_aligned(bytes, alignment); 3542 } 3543 3544 if (start == NULL) { 3545 return NULL; 3546 } 3547 3548 assert(is_ptr_aligned(start, alignment), "Must be"); 3549 3550 // os::reserve_memory_special will record this memory area. 3551 // Need to release it here to prevent overlapping reservations. 3552 MemTracker::record_virtual_memory_release((address)start, bytes); 3553 3554 char* end = start + bytes; 3555 3556 // Find the regions of the allocated chunk that can be promoted to large pages. 3557 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3558 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3559 3560 size_t lp_bytes = lp_end - lp_start; 3561 3562 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3563 3564 if (lp_bytes == 0) { 3565 // The mapped region doesn't even span the start and the end of a large page. 3566 // Fall back to allocate a non-special area. 3567 ::munmap(start, end - start); 3568 return NULL; 3569 } 3570 3571 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3572 3573 3574 void* result; 3575 3576 if (start != lp_start) { 3577 result = ::mmap(start, lp_start - start, prot, 3578 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3579 -1, 0); 3580 if (result == MAP_FAILED) { 3581 ::munmap(lp_start, end - lp_start); 3582 return NULL; 3583 } 3584 } 3585 3586 result = ::mmap(lp_start, lp_bytes, prot, 3587 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3588 -1, 0); 3589 if (result == MAP_FAILED) { 3590 warn_on_large_pages_failure(req_addr, bytes, errno); 3591 // If the mmap above fails, the large pages region will be unmapped and we 3592 // have regions before and after with small pages. Release these regions. 3593 // 3594 // | mapped | unmapped | mapped | 3595 // ^ ^ ^ ^ 3596 // start lp_start lp_end end 3597 // 3598 ::munmap(start, lp_start - start); 3599 ::munmap(lp_end, end - lp_end); 3600 return NULL; 3601 } 3602 3603 if (lp_end != end) { 3604 result = ::mmap(lp_end, end - lp_end, prot, 3605 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3606 -1, 0); 3607 if (result == MAP_FAILED) { 3608 ::munmap(start, lp_end - start); 3609 return NULL; 3610 } 3611 } 3612 3613 return start; 3614} 3615 3616char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3617 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3618 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3619 assert(is_power_of_2(alignment), "Must be"); 3620 assert(is_power_of_2(os::large_page_size()), "Must be"); 3621 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3622 3623 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3624 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3625 } else { 3626 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3627 } 3628} 3629 3630char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3631 assert(UseLargePages, "only for large pages"); 3632 3633 char* addr; 3634 if (UseSHM) { 3635 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3636 } else { 3637 assert(UseHugeTLBFS, "must be"); 3638 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3639 } 3640 3641 if (addr != NULL) { 3642 if (UseNUMAInterleaving) { 3643 numa_make_global(addr, bytes); 3644 } 3645 3646 // The memory is committed 3647 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, mtNone, CALLER_PC); 3648 } 3649 3650 return addr; 3651} 3652 3653bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3654 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3655 return shmdt(base) == 0; 3656} 3657 3658bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3659 return pd_release_memory(base, bytes); 3660} 3661 3662bool os::release_memory_special(char* base, size_t bytes) { 3663 assert(UseLargePages, "only for large pages"); 3664 3665 MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3666 3667 bool res; 3668 if (UseSHM) { 3669 res = os::Linux::release_memory_special_shm(base, bytes); 3670 } else { 3671 assert(UseHugeTLBFS, "must be"); 3672 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3673 } 3674 3675 if (res) { 3676 tkr.record((address)base, bytes); 3677 } else { 3678 tkr.discard(); 3679 } 3680 3681 return res; 3682} 3683 3684size_t os::large_page_size() { 3685 return _large_page_size; 3686} 3687 3688// With SysV SHM the entire memory region must be allocated as shared 3689// memory. 3690// HugeTLBFS allows application to commit large page memory on demand. 3691// However, when committing memory with HugeTLBFS fails, the region 3692// that was supposed to be committed will lose the old reservation 3693// and allow other threads to steal that memory region. Because of this 3694// behavior we can't commit HugeTLBFS memory. 3695bool os::can_commit_large_page_memory() { 3696 return UseTransparentHugePages; 3697} 3698 3699bool os::can_execute_large_page_memory() { 3700 return UseTransparentHugePages || UseHugeTLBFS; 3701} 3702 3703// Reserve memory at an arbitrary address, only if that area is 3704// available (and not reserved for something else). 3705 3706char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3707 const int max_tries = 10; 3708 char* base[max_tries]; 3709 size_t size[max_tries]; 3710 const size_t gap = 0x000000; 3711 3712 // Assert only that the size is a multiple of the page size, since 3713 // that's all that mmap requires, and since that's all we really know 3714 // about at this low abstraction level. If we need higher alignment, 3715 // we can either pass an alignment to this method or verify alignment 3716 // in one of the methods further up the call chain. See bug 5044738. 3717 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3718 3719 // Repeatedly allocate blocks until the block is allocated at the 3720 // right spot. Give up after max_tries. Note that reserve_memory() will 3721 // automatically update _highest_vm_reserved_address if the call is 3722 // successful. The variable tracks the highest memory address every reserved 3723 // by JVM. It is used to detect heap-stack collision if running with 3724 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3725 // space than needed, it could confuse the collision detecting code. To 3726 // solve the problem, save current _highest_vm_reserved_address and 3727 // calculate the correct value before return. 3728 address old_highest = _highest_vm_reserved_address; 3729 3730 // Linux mmap allows caller to pass an address as hint; give it a try first, 3731 // if kernel honors the hint then we can return immediately. 3732 char * addr = anon_mmap(requested_addr, bytes, false); 3733 if (addr == requested_addr) { 3734 return requested_addr; 3735 } 3736 3737 if (addr != NULL) { 3738 // mmap() is successful but it fails to reserve at the requested address 3739 anon_munmap(addr, bytes); 3740 } 3741 3742 int i; 3743 for (i = 0; i < max_tries; ++i) { 3744 base[i] = reserve_memory(bytes); 3745 3746 if (base[i] != NULL) { 3747 // Is this the block we wanted? 3748 if (base[i] == requested_addr) { 3749 size[i] = bytes; 3750 break; 3751 } 3752 3753 // Does this overlap the block we wanted? Give back the overlapped 3754 // parts and try again. 3755 3756 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3757 if (top_overlap >= 0 && top_overlap < bytes) { 3758 unmap_memory(base[i], top_overlap); 3759 base[i] += top_overlap; 3760 size[i] = bytes - top_overlap; 3761 } else { 3762 size_t bottom_overlap = base[i] + bytes - requested_addr; 3763 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3764 unmap_memory(requested_addr, bottom_overlap); 3765 size[i] = bytes - bottom_overlap; 3766 } else { 3767 size[i] = bytes; 3768 } 3769 } 3770 } 3771 } 3772 3773 // Give back the unused reserved pieces. 3774 3775 for (int j = 0; j < i; ++j) { 3776 if (base[j] != NULL) { 3777 unmap_memory(base[j], size[j]); 3778 } 3779 } 3780 3781 if (i < max_tries) { 3782 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3783 return requested_addr; 3784 } else { 3785 _highest_vm_reserved_address = old_highest; 3786 return NULL; 3787 } 3788} 3789 3790size_t os::read(int fd, void *buf, unsigned int nBytes) { 3791 return ::read(fd, buf, nBytes); 3792} 3793 3794// TODO-FIXME: reconcile Solaris' os::sleep with the linux variation. 3795// Solaris uses poll(), linux uses park(). 3796// Poll() is likely a better choice, assuming that Thread.interrupt() 3797// generates a SIGUSRx signal. Note that SIGUSR1 can interfere with 3798// SIGSEGV, see 4355769. 3799 3800int os::sleep(Thread* thread, jlong millis, bool interruptible) { 3801 assert(thread == Thread::current(), "thread consistency check"); 3802 3803 ParkEvent * const slp = thread->_SleepEvent ; 3804 slp->reset() ; 3805 OrderAccess::fence() ; 3806 3807 if (interruptible) { 3808 jlong prevtime = javaTimeNanos(); 3809 3810 for (;;) { 3811 if (os::is_interrupted(thread, true)) { 3812 return OS_INTRPT; 3813 } 3814 3815 jlong newtime = javaTimeNanos(); 3816 3817 if (newtime - prevtime < 0) { 3818 // time moving backwards, should only happen if no monotonic clock 3819 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3820 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3821 } else { 3822 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3823 } 3824 3825 if(millis <= 0) { 3826 return OS_OK; 3827 } 3828 3829 prevtime = newtime; 3830 3831 { 3832 assert(thread->is_Java_thread(), "sanity check"); 3833 JavaThread *jt = (JavaThread *) thread; 3834 ThreadBlockInVM tbivm(jt); 3835 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */); 3836 3837 jt->set_suspend_equivalent(); 3838 // cleared by handle_special_suspend_equivalent_condition() or 3839 // java_suspend_self() via check_and_wait_while_suspended() 3840 3841 slp->park(millis); 3842 3843 // were we externally suspended while we were waiting? 3844 jt->check_and_wait_while_suspended(); 3845 } 3846 } 3847 } else { 3848 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 3849 jlong prevtime = javaTimeNanos(); 3850 3851 for (;;) { 3852 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on 3853 // the 1st iteration ... 3854 jlong newtime = javaTimeNanos(); 3855 3856 if (newtime - prevtime < 0) { 3857 // time moving backwards, should only happen if no monotonic clock 3858 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3859 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3860 } else { 3861 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3862 } 3863 3864 if(millis <= 0) break ; 3865 3866 prevtime = newtime; 3867 slp->park(millis); 3868 } 3869 return OS_OK ; 3870 } 3871} 3872 3873int os::naked_sleep() { 3874 // %% make the sleep time an integer flag. for now use 1 millisec. 3875 return os::sleep(Thread::current(), 1, false); 3876} 3877 3878// Sleep forever; naked call to OS-specific sleep; use with CAUTION 3879void os::infinite_sleep() { 3880 while (true) { // sleep forever ... 3881 ::sleep(100); // ... 100 seconds at a time 3882 } 3883} 3884 3885// Used to convert frequent JVM_Yield() to nops 3886bool os::dont_yield() { 3887 return DontYieldALot; 3888} 3889 3890void os::yield() { 3891 sched_yield(); 3892} 3893 3894os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 3895 3896void os::yield_all(int attempts) { 3897 // Yields to all threads, including threads with lower priorities 3898 // Threads on Linux are all with same priority. The Solaris style 3899 // os::yield_all() with nanosleep(1ms) is not necessary. 3900 sched_yield(); 3901} 3902 3903// Called from the tight loops to possibly influence time-sharing heuristics 3904void os::loop_breaker(int attempts) { 3905 os::yield_all(attempts); 3906} 3907 3908//////////////////////////////////////////////////////////////////////////////// 3909// thread priority support 3910 3911// Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3912// only supports dynamic priority, static priority must be zero. For real-time 3913// applications, Linux supports SCHED_RR which allows static priority (1-99). 3914// However, for large multi-threaded applications, SCHED_RR is not only slower 3915// than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3916// of 5 runs - Sep 2005). 3917// 3918// The following code actually changes the niceness of kernel-thread/LWP. It 3919// has an assumption that setpriority() only modifies one kernel-thread/LWP, 3920// not the entire user process, and user level threads are 1:1 mapped to kernel 3921// threads. It has always been the case, but could change in the future. For 3922// this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3923// It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3924 3925int os::java_to_os_priority[CriticalPriority + 1] = { 3926 19, // 0 Entry should never be used 3927 3928 4, // 1 MinPriority 3929 3, // 2 3930 2, // 3 3931 3932 1, // 4 3933 0, // 5 NormPriority 3934 -1, // 6 3935 3936 -2, // 7 3937 -3, // 8 3938 -4, // 9 NearMaxPriority 3939 3940 -5, // 10 MaxPriority 3941 3942 -5 // 11 CriticalPriority 3943}; 3944 3945static int prio_init() { 3946 if (ThreadPriorityPolicy == 1) { 3947 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3948 // if effective uid is not root. Perhaps, a more elegant way of doing 3949 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3950 if (geteuid() != 0) { 3951 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3952 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3953 } 3954 ThreadPriorityPolicy = 0; 3955 } 3956 } 3957 if (UseCriticalJavaThreadPriority) { 3958 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3959 } 3960 return 0; 3961} 3962 3963OSReturn os::set_native_priority(Thread* thread, int newpri) { 3964 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 3965 3966 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3967 return (ret == 0) ? OS_OK : OS_ERR; 3968} 3969 3970OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3971 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3972 *priority_ptr = java_to_os_priority[NormPriority]; 3973 return OS_OK; 3974 } 3975 3976 errno = 0; 3977 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3978 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3979} 3980 3981// Hint to the underlying OS that a task switch would not be good. 3982// Void return because it's a hint and can fail. 3983void os::hint_no_preempt() {} 3984 3985//////////////////////////////////////////////////////////////////////////////// 3986// suspend/resume support 3987 3988// the low-level signal-based suspend/resume support is a remnant from the 3989// old VM-suspension that used to be for java-suspension, safepoints etc, 3990// within hotspot. Now there is a single use-case for this: 3991// - calling get_thread_pc() on the VMThread by the flat-profiler task 3992// that runs in the watcher thread. 3993// The remaining code is greatly simplified from the more general suspension 3994// code that used to be used. 3995// 3996// The protocol is quite simple: 3997// - suspend: 3998// - sends a signal to the target thread 3999// - polls the suspend state of the osthread using a yield loop 4000// - target thread signal handler (SR_handler) sets suspend state 4001// and blocks in sigsuspend until continued 4002// - resume: 4003// - sets target osthread state to continue 4004// - sends signal to end the sigsuspend loop in the SR_handler 4005// 4006// Note that the SR_lock plays no role in this suspend/resume protocol. 4007// 4008 4009static void resume_clear_context(OSThread *osthread) { 4010 osthread->set_ucontext(NULL); 4011 osthread->set_siginfo(NULL); 4012} 4013 4014static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 4015 osthread->set_ucontext(context); 4016 osthread->set_siginfo(siginfo); 4017} 4018 4019// 4020// Handler function invoked when a thread's execution is suspended or 4021// resumed. We have to be careful that only async-safe functions are 4022// called here (Note: most pthread functions are not async safe and 4023// should be avoided.) 4024// 4025// Note: sigwait() is a more natural fit than sigsuspend() from an 4026// interface point of view, but sigwait() prevents the signal hander 4027// from being run. libpthread would get very confused by not having 4028// its signal handlers run and prevents sigwait()'s use with the 4029// mutex granting granting signal. 4030// 4031// Currently only ever called on the VMThread and JavaThreads (PC sampling) 4032// 4033static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 4034 // Save and restore errno to avoid confusing native code with EINTR 4035 // after sigsuspend. 4036 int old_errno = errno; 4037 4038 Thread* thread = Thread::current(); 4039 OSThread* osthread = thread->osthread(); 4040 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 4041 4042 os::SuspendResume::State current = osthread->sr.state(); 4043 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 4044 suspend_save_context(osthread, siginfo, context); 4045 4046 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 4047 os::SuspendResume::State state = osthread->sr.suspended(); 4048 if (state == os::SuspendResume::SR_SUSPENDED) { 4049 sigset_t suspend_set; // signals for sigsuspend() 4050 4051 // get current set of blocked signals and unblock resume signal 4052 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 4053 sigdelset(&suspend_set, SR_signum); 4054 4055 sr_semaphore.signal(); 4056 // wait here until we are resumed 4057 while (1) { 4058 sigsuspend(&suspend_set); 4059 4060 os::SuspendResume::State result = osthread->sr.running(); 4061 if (result == os::SuspendResume::SR_RUNNING) { 4062 sr_semaphore.signal(); 4063 break; 4064 } 4065 } 4066 4067 } else if (state == os::SuspendResume::SR_RUNNING) { 4068 // request was cancelled, continue 4069 } else { 4070 ShouldNotReachHere(); 4071 } 4072 4073 resume_clear_context(osthread); 4074 } else if (current == os::SuspendResume::SR_RUNNING) { 4075 // request was cancelled, continue 4076 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 4077 // ignore 4078 } else { 4079 // ignore 4080 } 4081 4082 errno = old_errno; 4083} 4084 4085 4086static int SR_initialize() { 4087 struct sigaction act; 4088 char *s; 4089 /* Get signal number to use for suspend/resume */ 4090 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 4091 int sig = ::strtol(s, 0, 10); 4092 if (sig > 0 || sig < _NSIG) { 4093 SR_signum = sig; 4094 } 4095 } 4096 4097 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 4098 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 4099 4100 sigemptyset(&SR_sigset); 4101 sigaddset(&SR_sigset, SR_signum); 4102 4103 /* Set up signal handler for suspend/resume */ 4104 act.sa_flags = SA_RESTART|SA_SIGINFO; 4105 act.sa_handler = (void (*)(int)) SR_handler; 4106 4107 // SR_signum is blocked by default. 4108 // 4528190 - We also need to block pthread restart signal (32 on all 4109 // supported Linux platforms). Note that LinuxThreads need to block 4110 // this signal for all threads to work properly. So we don't have 4111 // to use hard-coded signal number when setting up the mask. 4112 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4113 4114 if (sigaction(SR_signum, &act, 0) == -1) { 4115 return -1; 4116 } 4117 4118 // Save signal flag 4119 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4120 return 0; 4121} 4122 4123static int sr_notify(OSThread* osthread) { 4124 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4125 assert_status(status == 0, status, "pthread_kill"); 4126 return status; 4127} 4128 4129// "Randomly" selected value for how long we want to spin 4130// before bailing out on suspending a thread, also how often 4131// we send a signal to a thread we want to resume 4132static const int RANDOMLY_LARGE_INTEGER = 1000000; 4133static const int RANDOMLY_LARGE_INTEGER2 = 100; 4134 4135// returns true on success and false on error - really an error is fatal 4136// but this seems the normal response to library errors 4137static bool do_suspend(OSThread* osthread) { 4138 assert(osthread->sr.is_running(), "thread should be running"); 4139 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4140 4141 // mark as suspended and send signal 4142 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4143 // failed to switch, state wasn't running? 4144 ShouldNotReachHere(); 4145 return false; 4146 } 4147 4148 if (sr_notify(osthread) != 0) { 4149 ShouldNotReachHere(); 4150 } 4151 4152 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4153 while (true) { 4154 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4155 break; 4156 } else { 4157 // timeout 4158 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4159 if (cancelled == os::SuspendResume::SR_RUNNING) { 4160 return false; 4161 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4162 // make sure that we consume the signal on the semaphore as well 4163 sr_semaphore.wait(); 4164 break; 4165 } else { 4166 ShouldNotReachHere(); 4167 return false; 4168 } 4169 } 4170 } 4171 4172 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4173 return true; 4174} 4175 4176static void do_resume(OSThread* osthread) { 4177 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4178 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4179 4180 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4181 // failed to switch to WAKEUP_REQUEST 4182 ShouldNotReachHere(); 4183 return; 4184 } 4185 4186 while (true) { 4187 if (sr_notify(osthread) == 0) { 4188 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4189 if (osthread->sr.is_running()) { 4190 return; 4191 } 4192 } 4193 } else { 4194 ShouldNotReachHere(); 4195 } 4196 } 4197 4198 guarantee(osthread->sr.is_running(), "Must be running!"); 4199} 4200 4201//////////////////////////////////////////////////////////////////////////////// 4202// interrupt support 4203 4204void os::interrupt(Thread* thread) { 4205 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 4206 "possibility of dangling Thread pointer"); 4207 4208 OSThread* osthread = thread->osthread(); 4209 4210 if (!osthread->interrupted()) { 4211 osthread->set_interrupted(true); 4212 // More than one thread can get here with the same value of osthread, 4213 // resulting in multiple notifications. We do, however, want the store 4214 // to interrupted() to be visible to other threads before we execute unpark(). 4215 OrderAccess::fence(); 4216 ParkEvent * const slp = thread->_SleepEvent ; 4217 if (slp != NULL) slp->unpark() ; 4218 } 4219 4220 // For JSR166. Unpark even if interrupt status already was set 4221 if (thread->is_Java_thread()) 4222 ((JavaThread*)thread)->parker()->unpark(); 4223 4224 ParkEvent * ev = thread->_ParkEvent ; 4225 if (ev != NULL) ev->unpark() ; 4226 4227} 4228 4229bool os::is_interrupted(Thread* thread, bool clear_interrupted) { 4230 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 4231 "possibility of dangling Thread pointer"); 4232 4233 OSThread* osthread = thread->osthread(); 4234 4235 bool interrupted = osthread->interrupted(); 4236 4237 if (interrupted && clear_interrupted) { 4238 osthread->set_interrupted(false); 4239 // consider thread->_SleepEvent->reset() ... optional optimization 4240 } 4241 4242 return interrupted; 4243} 4244 4245/////////////////////////////////////////////////////////////////////////////////// 4246// signal handling (except suspend/resume) 4247 4248// This routine may be used by user applications as a "hook" to catch signals. 4249// The user-defined signal handler must pass unrecognized signals to this 4250// routine, and if it returns true (non-zero), then the signal handler must 4251// return immediately. If the flag "abort_if_unrecognized" is true, then this 4252// routine will never retun false (zero), but instead will execute a VM panic 4253// routine kill the process. 4254// 4255// If this routine returns false, it is OK to call it again. This allows 4256// the user-defined signal handler to perform checks either before or after 4257// the VM performs its own checks. Naturally, the user code would be making 4258// a serious error if it tried to handle an exception (such as a null check 4259// or breakpoint) that the VM was generating for its own correct operation. 4260// 4261// This routine may recognize any of the following kinds of signals: 4262// SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4263// It should be consulted by handlers for any of those signals. 4264// 4265// The caller of this routine must pass in the three arguments supplied 4266// to the function referred to in the "sa_sigaction" (not the "sa_handler") 4267// field of the structure passed to sigaction(). This routine assumes that 4268// the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4269// 4270// Note that the VM will print warnings if it detects conflicting signal 4271// handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4272// 4273extern "C" JNIEXPORT int 4274JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 4275 void* ucontext, int abort_if_unrecognized); 4276 4277void signalHandler(int sig, siginfo_t* info, void* uc) { 4278 assert(info != NULL && uc != NULL, "it must be old kernel"); 4279 int orig_errno = errno; // Preserve errno value over signal handler. 4280 JVM_handle_linux_signal(sig, info, uc, true); 4281 errno = orig_errno; 4282} 4283 4284 4285// This boolean allows users to forward their own non-matching signals 4286// to JVM_handle_linux_signal, harmlessly. 4287bool os::Linux::signal_handlers_are_installed = false; 4288 4289// For signal-chaining 4290struct sigaction os::Linux::sigact[MAXSIGNUM]; 4291unsigned int os::Linux::sigs = 0; 4292bool os::Linux::libjsig_is_loaded = false; 4293typedef struct sigaction *(*get_signal_t)(int); 4294get_signal_t os::Linux::get_signal_action = NULL; 4295 4296struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4297 struct sigaction *actp = NULL; 4298 4299 if (libjsig_is_loaded) { 4300 // Retrieve the old signal handler from libjsig 4301 actp = (*get_signal_action)(sig); 4302 } 4303 if (actp == NULL) { 4304 // Retrieve the preinstalled signal handler from jvm 4305 actp = get_preinstalled_handler(sig); 4306 } 4307 4308 return actp; 4309} 4310 4311static bool call_chained_handler(struct sigaction *actp, int sig, 4312 siginfo_t *siginfo, void *context) { 4313 // Call the old signal handler 4314 if (actp->sa_handler == SIG_DFL) { 4315 // It's more reasonable to let jvm treat it as an unexpected exception 4316 // instead of taking the default action. 4317 return false; 4318 } else if (actp->sa_handler != SIG_IGN) { 4319 if ((actp->sa_flags & SA_NODEFER) == 0) { 4320 // automaticlly block the signal 4321 sigaddset(&(actp->sa_mask), sig); 4322 } 4323 4324 sa_handler_t hand; 4325 sa_sigaction_t sa; 4326 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4327 // retrieve the chained handler 4328 if (siginfo_flag_set) { 4329 sa = actp->sa_sigaction; 4330 } else { 4331 hand = actp->sa_handler; 4332 } 4333 4334 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4335 actp->sa_handler = SIG_DFL; 4336 } 4337 4338 // try to honor the signal mask 4339 sigset_t oset; 4340 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4341 4342 // call into the chained handler 4343 if (siginfo_flag_set) { 4344 (*sa)(sig, siginfo, context); 4345 } else { 4346 (*hand)(sig); 4347 } 4348 4349 // restore the signal mask 4350 pthread_sigmask(SIG_SETMASK, &oset, 0); 4351 } 4352 // Tell jvm's signal handler the signal is taken care of. 4353 return true; 4354} 4355 4356bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4357 bool chained = false; 4358 // signal-chaining 4359 if (UseSignalChaining) { 4360 struct sigaction *actp = get_chained_signal_action(sig); 4361 if (actp != NULL) { 4362 chained = call_chained_handler(actp, sig, siginfo, context); 4363 } 4364 } 4365 return chained; 4366} 4367 4368struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4369 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 4370 return &sigact[sig]; 4371 } 4372 return NULL; 4373} 4374 4375void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4376 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4377 sigact[sig] = oldAct; 4378 sigs |= (unsigned int)1 << sig; 4379} 4380 4381// for diagnostic 4382int os::Linux::sigflags[MAXSIGNUM]; 4383 4384int os::Linux::get_our_sigflags(int sig) { 4385 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4386 return sigflags[sig]; 4387} 4388 4389void os::Linux::set_our_sigflags(int sig, int flags) { 4390 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4391 sigflags[sig] = flags; 4392} 4393 4394void os::Linux::set_signal_handler(int sig, bool set_installed) { 4395 // Check for overwrite. 4396 struct sigaction oldAct; 4397 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4398 4399 void* oldhand = oldAct.sa_sigaction 4400 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4401 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4402 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4403 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4404 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4405 if (AllowUserSignalHandlers || !set_installed) { 4406 // Do not overwrite; user takes responsibility to forward to us. 4407 return; 4408 } else if (UseSignalChaining) { 4409 // save the old handler in jvm 4410 save_preinstalled_handler(sig, oldAct); 4411 // libjsig also interposes the sigaction() call below and saves the 4412 // old sigaction on it own. 4413 } else { 4414 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4415 "%#lx for signal %d.", (long)oldhand, sig)); 4416 } 4417 } 4418 4419 struct sigaction sigAct; 4420 sigfillset(&(sigAct.sa_mask)); 4421 sigAct.sa_handler = SIG_DFL; 4422 if (!set_installed) { 4423 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4424 } else { 4425 sigAct.sa_sigaction = signalHandler; 4426 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4427 } 4428 // Save flags, which are set by ours 4429 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4430 sigflags[sig] = sigAct.sa_flags; 4431 4432 int ret = sigaction(sig, &sigAct, &oldAct); 4433 assert(ret == 0, "check"); 4434 4435 void* oldhand2 = oldAct.sa_sigaction 4436 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4437 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4438 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4439} 4440 4441// install signal handlers for signals that HotSpot needs to 4442// handle in order to support Java-level exception handling. 4443 4444void os::Linux::install_signal_handlers() { 4445 if (!signal_handlers_are_installed) { 4446 signal_handlers_are_installed = true; 4447 4448 // signal-chaining 4449 typedef void (*signal_setting_t)(); 4450 signal_setting_t begin_signal_setting = NULL; 4451 signal_setting_t end_signal_setting = NULL; 4452 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4453 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4454 if (begin_signal_setting != NULL) { 4455 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4456 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4457 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4458 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4459 libjsig_is_loaded = true; 4460 assert(UseSignalChaining, "should enable signal-chaining"); 4461 } 4462 if (libjsig_is_loaded) { 4463 // Tell libjsig jvm is setting signal handlers 4464 (*begin_signal_setting)(); 4465 } 4466 4467 set_signal_handler(SIGSEGV, true); 4468 set_signal_handler(SIGPIPE, true); 4469 set_signal_handler(SIGBUS, true); 4470 set_signal_handler(SIGILL, true); 4471 set_signal_handler(SIGFPE, true); 4472 set_signal_handler(SIGXFSZ, true); 4473 4474 if (libjsig_is_loaded) { 4475 // Tell libjsig jvm finishes setting signal handlers 4476 (*end_signal_setting)(); 4477 } 4478 4479 // We don't activate signal checker if libjsig is in place, we trust ourselves 4480 // and if UserSignalHandler is installed all bets are off. 4481 // Log that signal checking is off only if -verbose:jni is specified. 4482 if (CheckJNICalls) { 4483 if (libjsig_is_loaded) { 4484 if (PrintJNIResolving) { 4485 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4486 } 4487 check_signals = false; 4488 } 4489 if (AllowUserSignalHandlers) { 4490 if (PrintJNIResolving) { 4491 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4492 } 4493 check_signals = false; 4494 } 4495 } 4496 } 4497} 4498 4499// This is the fastest way to get thread cpu time on Linux. 4500// Returns cpu time (user+sys) for any thread, not only for current. 4501// POSIX compliant clocks are implemented in the kernels 2.6.16+. 4502// It might work on 2.6.10+ with a special kernel/glibc patch. 4503// For reference, please, see IEEE Std 1003.1-2004: 4504// http://www.unix.org/single_unix_specification 4505 4506jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4507 struct timespec tp; 4508 int rc = os::Linux::clock_gettime(clockid, &tp); 4509 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4510 4511 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4512} 4513 4514///// 4515// glibc on Linux platform uses non-documented flag 4516// to indicate, that some special sort of signal 4517// trampoline is used. 4518// We will never set this flag, and we should 4519// ignore this flag in our diagnostic 4520#ifdef SIGNIFICANT_SIGNAL_MASK 4521#undef SIGNIFICANT_SIGNAL_MASK 4522#endif 4523#define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4524 4525static const char* get_signal_handler_name(address handler, 4526 char* buf, int buflen) { 4527 int offset; 4528 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4529 if (found) { 4530 // skip directory names 4531 const char *p1, *p2; 4532 p1 = buf; 4533 size_t len = strlen(os::file_separator()); 4534 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4535 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4536 } else { 4537 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4538 } 4539 return buf; 4540} 4541 4542static void print_signal_handler(outputStream* st, int sig, 4543 char* buf, size_t buflen) { 4544 struct sigaction sa; 4545 4546 sigaction(sig, NULL, &sa); 4547 4548 // See comment for SIGNIFICANT_SIGNAL_MASK define 4549 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4550 4551 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4552 4553 address handler = (sa.sa_flags & SA_SIGINFO) 4554 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4555 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4556 4557 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4558 st->print("SIG_DFL"); 4559 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4560 st->print("SIG_IGN"); 4561 } else { 4562 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4563 } 4564 4565 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask); 4566 4567 address rh = VMError::get_resetted_sighandler(sig); 4568 // May be, handler was resetted by VMError? 4569 if(rh != NULL) { 4570 handler = rh; 4571 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4572 } 4573 4574 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags); 4575 4576 // Check: is it our handler? 4577 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4578 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4579 // It is our signal handler 4580 // check for flags, reset system-used one! 4581 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4582 st->print( 4583 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4584 os::Linux::get_our_sigflags(sig)); 4585 } 4586 } 4587 st->cr(); 4588} 4589 4590 4591#define DO_SIGNAL_CHECK(sig) \ 4592 if (!sigismember(&check_signal_done, sig)) \ 4593 os::Linux::check_signal_handler(sig) 4594 4595// This method is a periodic task to check for misbehaving JNI applications 4596// under CheckJNI, we can add any periodic checks here 4597 4598void os::run_periodic_checks() { 4599 4600 if (check_signals == false) return; 4601 4602 // SEGV and BUS if overridden could potentially prevent 4603 // generation of hs*.log in the event of a crash, debugging 4604 // such a case can be very challenging, so we absolutely 4605 // check the following for a good measure: 4606 DO_SIGNAL_CHECK(SIGSEGV); 4607 DO_SIGNAL_CHECK(SIGILL); 4608 DO_SIGNAL_CHECK(SIGFPE); 4609 DO_SIGNAL_CHECK(SIGBUS); 4610 DO_SIGNAL_CHECK(SIGPIPE); 4611 DO_SIGNAL_CHECK(SIGXFSZ); 4612 4613 4614 // ReduceSignalUsage allows the user to override these handlers 4615 // see comments at the very top and jvm_solaris.h 4616 if (!ReduceSignalUsage) { 4617 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4618 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4619 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4620 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4621 } 4622 4623 DO_SIGNAL_CHECK(SR_signum); 4624 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4625} 4626 4627typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4628 4629static os_sigaction_t os_sigaction = NULL; 4630 4631void os::Linux::check_signal_handler(int sig) { 4632 char buf[O_BUFLEN]; 4633 address jvmHandler = NULL; 4634 4635 4636 struct sigaction act; 4637 if (os_sigaction == NULL) { 4638 // only trust the default sigaction, in case it has been interposed 4639 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4640 if (os_sigaction == NULL) return; 4641 } 4642 4643 os_sigaction(sig, (struct sigaction*)NULL, &act); 4644 4645 4646 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4647 4648 address thisHandler = (act.sa_flags & SA_SIGINFO) 4649 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4650 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 4651 4652 4653 switch(sig) { 4654 case SIGSEGV: 4655 case SIGBUS: 4656 case SIGFPE: 4657 case SIGPIPE: 4658 case SIGILL: 4659 case SIGXFSZ: 4660 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4661 break; 4662 4663 case SHUTDOWN1_SIGNAL: 4664 case SHUTDOWN2_SIGNAL: 4665 case SHUTDOWN3_SIGNAL: 4666 case BREAK_SIGNAL: 4667 jvmHandler = (address)user_handler(); 4668 break; 4669 4670 case INTERRUPT_SIGNAL: 4671 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4672 break; 4673 4674 default: 4675 if (sig == SR_signum) { 4676 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4677 } else { 4678 return; 4679 } 4680 break; 4681 } 4682 4683 if (thisHandler != jvmHandler) { 4684 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4685 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4686 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4687 // No need to check this sig any longer 4688 sigaddset(&check_signal_done, sig); 4689 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4690 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4691 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4692 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4693 // No need to check this sig any longer 4694 sigaddset(&check_signal_done, sig); 4695 } 4696 4697 // Dump all the signal 4698 if (sigismember(&check_signal_done, sig)) { 4699 print_signal_handlers(tty, buf, O_BUFLEN); 4700 } 4701} 4702 4703extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 4704 4705extern bool signal_name(int signo, char* buf, size_t len); 4706 4707const char* os::exception_name(int exception_code, char* buf, size_t size) { 4708 if (0 < exception_code && exception_code <= SIGRTMAX) { 4709 // signal 4710 if (!signal_name(exception_code, buf, size)) { 4711 jio_snprintf(buf, size, "SIG%d", exception_code); 4712 } 4713 return buf; 4714 } else { 4715 return NULL; 4716 } 4717} 4718 4719// this is called _before_ the most of global arguments have been parsed 4720void os::init(void) { 4721 char dummy; /* used to get a guess on initial stack address */ 4722// first_hrtime = gethrtime(); 4723 4724 // With LinuxThreads the JavaMain thread pid (primordial thread) 4725 // is different than the pid of the java launcher thread. 4726 // So, on Linux, the launcher thread pid is passed to the VM 4727 // via the sun.java.launcher.pid property. 4728 // Use this property instead of getpid() if it was correctly passed. 4729 // See bug 6351349. 4730 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4731 4732 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4733 4734 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4735 4736 init_random(1234567); 4737 4738 ThreadCritical::initialize(); 4739 4740 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4741 if (Linux::page_size() == -1) { 4742 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4743 strerror(errno))); 4744 } 4745 init_page_sizes((size_t) Linux::page_size()); 4746 4747 Linux::initialize_system_info(); 4748 4749 // main_thread points to the aboriginal thread 4750 Linux::_main_thread = pthread_self(); 4751 4752 Linux::clock_init(); 4753 initial_time_count = os::elapsed_counter(); 4754 4755 // pthread_condattr initialization for monotonic clock 4756 int status; 4757 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4758 if ((status = pthread_condattr_init(_condattr)) != 0) { 4759 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4760 } 4761 // Only set the clock if CLOCK_MONOTONIC is available 4762 if (Linux::supports_monotonic_clock()) { 4763 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4764 if (status == EINVAL) { 4765 warning("Unable to use monotonic clock with relative timed-waits" \ 4766 " - changes to the time-of-day clock may have adverse affects"); 4767 } else { 4768 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4769 } 4770 } 4771 } 4772 // else it defaults to CLOCK_REALTIME 4773 4774 pthread_mutex_init(&dl_mutex, NULL); 4775 4776 // If the pagesize of the VM is greater than 8K determine the appropriate 4777 // number of initial guard pages. The user can change this with the 4778 // command line arguments, if needed. 4779 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4780 StackYellowPages = 1; 4781 StackRedPages = 1; 4782 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4783 } 4784} 4785 4786// To install functions for atexit system call 4787extern "C" { 4788 static void perfMemory_exit_helper() { 4789 perfMemory_exit(); 4790 } 4791} 4792 4793// this is called _after_ the global arguments have been parsed 4794jint os::init_2(void) 4795{ 4796 Linux::fast_thread_clock_init(); 4797 4798 // Allocate a single page and mark it as readable for safepoint polling 4799 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4800 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 4801 4802 os::set_polling_page( polling_page ); 4803 4804#ifndef PRODUCT 4805 if(Verbose && PrintMiscellaneous) 4806 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 4807#endif 4808 4809 if (!UseMembar) { 4810 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4811 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4812 os::set_memory_serialize_page( mem_serialize_page ); 4813 4814#ifndef PRODUCT 4815 if(Verbose && PrintMiscellaneous) 4816 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 4817#endif 4818 } 4819 4820 // initialize suspend/resume support - must do this before signal_sets_init() 4821 if (SR_initialize() != 0) { 4822 perror("SR_initialize failed"); 4823 return JNI_ERR; 4824 } 4825 4826 Linux::signal_sets_init(); 4827 Linux::install_signal_handlers(); 4828 4829 // Check minimum allowable stack size for thread creation and to initialize 4830 // the java system classes, including StackOverflowError - depends on page 4831 // size. Add a page for compiler2 recursion in main thread. 4832 // Add in 2*BytesPerWord times page size to account for VM stack during 4833 // class initialization depending on 32 or 64 bit VM. 4834 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4835 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4836 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4837 4838 size_t threadStackSizeInBytes = ThreadStackSize * K; 4839 if (threadStackSizeInBytes != 0 && 4840 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4841 tty->print_cr("\nThe stack size specified is too small, " 4842 "Specify at least %dk", 4843 os::Linux::min_stack_allowed/ K); 4844 return JNI_ERR; 4845 } 4846 4847 // Make the stack size a multiple of the page size so that 4848 // the yellow/red zones can be guarded. 4849 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4850 vm_page_size())); 4851 4852 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4853 4854#if defined(IA32) 4855 workaround_expand_exec_shield_cs_limit(); 4856#endif 4857 4858 Linux::libpthread_init(); 4859 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4860 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4861 Linux::glibc_version(), Linux::libpthread_version(), 4862 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4863 } 4864 4865 if (UseNUMA) { 4866 if (!Linux::libnuma_init()) { 4867 UseNUMA = false; 4868 } else { 4869 if ((Linux::numa_max_node() < 1)) { 4870 // There's only one node(they start from 0), disable NUMA. 4871 UseNUMA = false; 4872 } 4873 } 4874 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4875 // we can make the adaptive lgrp chunk resizing work. If the user specified 4876 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4877 // disable adaptive resizing. 4878 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4879 if (FLAG_IS_DEFAULT(UseNUMA)) { 4880 UseNUMA = false; 4881 } else { 4882 if (FLAG_IS_DEFAULT(UseLargePages) && 4883 FLAG_IS_DEFAULT(UseSHM) && 4884 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4885 UseLargePages = false; 4886 } else { 4887 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4888 UseAdaptiveSizePolicy = false; 4889 UseAdaptiveNUMAChunkSizing = false; 4890 } 4891 } 4892 } 4893 if (!UseNUMA && ForceNUMA) { 4894 UseNUMA = true; 4895 } 4896 } 4897 4898 if (MaxFDLimit) { 4899 // set the number of file descriptors to max. print out error 4900 // if getrlimit/setrlimit fails but continue regardless. 4901 struct rlimit nbr_files; 4902 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4903 if (status != 0) { 4904 if (PrintMiscellaneous && (Verbose || WizardMode)) 4905 perror("os::init_2 getrlimit failed"); 4906 } else { 4907 nbr_files.rlim_cur = nbr_files.rlim_max; 4908 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4909 if (status != 0) { 4910 if (PrintMiscellaneous && (Verbose || WizardMode)) 4911 perror("os::init_2 setrlimit failed"); 4912 } 4913 } 4914 } 4915 4916 // Initialize lock used to serialize thread creation (see os::create_thread) 4917 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4918 4919 // at-exit methods are called in the reverse order of their registration. 4920 // atexit functions are called on return from main or as a result of a 4921 // call to exit(3C). There can be only 32 of these functions registered 4922 // and atexit() does not set errno. 4923 4924 if (PerfAllowAtExitRegistration) { 4925 // only register atexit functions if PerfAllowAtExitRegistration is set. 4926 // atexit functions can be delayed until process exit time, which 4927 // can be problematic for embedded VM situations. Embedded VMs should 4928 // call DestroyJavaVM() to assure that VM resources are released. 4929 4930 // note: perfMemory_exit_helper atexit function may be removed in 4931 // the future if the appropriate cleanup code can be added to the 4932 // VM_Exit VMOperation's doit method. 4933 if (atexit(perfMemory_exit_helper) != 0) { 4934 warning("os::init2 atexit(perfMemory_exit_helper) failed"); 4935 } 4936 } 4937 4938 // initialize thread priority policy 4939 prio_init(); 4940 4941 return JNI_OK; 4942} 4943 4944// this is called at the end of vm_initialization 4945void os::init_3(void) 4946{ 4947#ifdef JAVASE_EMBEDDED 4948 // Start the MemNotifyThread 4949 if (LowMemoryProtection) { 4950 MemNotifyThread::start(); 4951 } 4952 return; 4953#endif 4954} 4955 4956// Mark the polling page as unreadable 4957void os::make_polling_page_unreadable(void) { 4958 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 4959 fatal("Could not disable polling page"); 4960}; 4961 4962// Mark the polling page as readable 4963void os::make_polling_page_readable(void) { 4964 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4965 fatal("Could not enable polling page"); 4966 } 4967}; 4968 4969int os::active_processor_count() { 4970 // Linux doesn't yet have a (official) notion of processor sets, 4971 // so just return the number of online processors. 4972 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4973 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4974 return online_cpus; 4975} 4976 4977void os::set_native_thread_name(const char *name) { 4978 // Not yet implemented. 4979 return; 4980} 4981 4982bool os::distribute_processes(uint length, uint* distribution) { 4983 // Not yet implemented. 4984 return false; 4985} 4986 4987bool os::bind_to_processor(uint processor_id) { 4988 // Not yet implemented. 4989 return false; 4990} 4991 4992/// 4993 4994void os::SuspendedThreadTask::internal_do_task() { 4995 if (do_suspend(_thread->osthread())) { 4996 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4997 do_task(context); 4998 do_resume(_thread->osthread()); 4999 } 5000} 5001 5002class PcFetcher : public os::SuspendedThreadTask { 5003public: 5004 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 5005 ExtendedPC result(); 5006protected: 5007 void do_task(const os::SuspendedThreadTaskContext& context); 5008private: 5009 ExtendedPC _epc; 5010}; 5011 5012ExtendedPC PcFetcher::result() { 5013 guarantee(is_done(), "task is not done yet."); 5014 return _epc; 5015} 5016 5017void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 5018 Thread* thread = context.thread(); 5019 OSThread* osthread = thread->osthread(); 5020 if (osthread->ucontext() != NULL) { 5021 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 5022 } else { 5023 // NULL context is unexpected, double-check this is the VMThread 5024 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 5025 } 5026} 5027 5028// Suspends the target using the signal mechanism and then grabs the PC before 5029// resuming the target. Used by the flat-profiler only 5030ExtendedPC os::get_thread_pc(Thread* thread) { 5031 // Make sure that it is called by the watcher for the VMThread 5032 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 5033 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 5034 5035 PcFetcher fetcher(thread); 5036 fetcher.run(); 5037 return fetcher.result(); 5038} 5039 5040int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 5041{ 5042 if (is_NPTL()) { 5043 return pthread_cond_timedwait(_cond, _mutex, _abstime); 5044 } else { 5045 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 5046 // word back to default 64bit precision if condvar is signaled. Java 5047 // wants 53bit precision. Save and restore current value. 5048 int fpu = get_fpu_control_word(); 5049 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 5050 set_fpu_control_word(fpu); 5051 return status; 5052 } 5053} 5054 5055//////////////////////////////////////////////////////////////////////////////// 5056// debug support 5057 5058bool os::find(address addr, outputStream* st) { 5059 Dl_info dlinfo; 5060 memset(&dlinfo, 0, sizeof(dlinfo)); 5061 if (dladdr(addr, &dlinfo) != 0) { 5062 st->print(PTR_FORMAT ": ", addr); 5063 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 5064 st->print("%s+%#x", dlinfo.dli_sname, 5065 addr - (intptr_t)dlinfo.dli_saddr); 5066 } else if (dlinfo.dli_fbase != NULL) { 5067 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 5068 } else { 5069 st->print("<absolute address>"); 5070 } 5071 if (dlinfo.dli_fname != NULL) { 5072 st->print(" in %s", dlinfo.dli_fname); 5073 } 5074 if (dlinfo.dli_fbase != NULL) { 5075 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 5076 } 5077 st->cr(); 5078 5079 if (Verbose) { 5080 // decode some bytes around the PC 5081 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 5082 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 5083 address lowest = (address) dlinfo.dli_sname; 5084 if (!lowest) lowest = (address) dlinfo.dli_fbase; 5085 if (begin < lowest) begin = lowest; 5086 Dl_info dlinfo2; 5087 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 5088 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 5089 end = (address) dlinfo2.dli_saddr; 5090 Disassembler::decode(begin, end, st); 5091 } 5092 return true; 5093 } 5094 return false; 5095} 5096 5097//////////////////////////////////////////////////////////////////////////////// 5098// misc 5099 5100// This does not do anything on Linux. This is basically a hook for being 5101// able to use structured exception handling (thread-local exception filters) 5102// on, e.g., Win32. 5103void 5104os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 5105 JavaCallArguments* args, Thread* thread) { 5106 f(value, method, args, thread); 5107} 5108 5109void os::print_statistics() { 5110} 5111 5112int os::message_box(const char* title, const char* message) { 5113 int i; 5114 fdStream err(defaultStream::error_fd()); 5115 for (i = 0; i < 78; i++) err.print_raw("="); 5116 err.cr(); 5117 err.print_raw_cr(title); 5118 for (i = 0; i < 78; i++) err.print_raw("-"); 5119 err.cr(); 5120 err.print_raw_cr(message); 5121 for (i = 0; i < 78; i++) err.print_raw("="); 5122 err.cr(); 5123 5124 char buf[16]; 5125 // Prevent process from exiting upon "read error" without consuming all CPU 5126 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 5127 5128 return buf[0] == 'y' || buf[0] == 'Y'; 5129} 5130 5131int os::stat(const char *path, struct stat *sbuf) { 5132 char pathbuf[MAX_PATH]; 5133 if (strlen(path) > MAX_PATH - 1) { 5134 errno = ENAMETOOLONG; 5135 return -1; 5136 } 5137 os::native_path(strcpy(pathbuf, path)); 5138 return ::stat(pathbuf, sbuf); 5139} 5140 5141bool os::check_heap(bool force) { 5142 return true; 5143} 5144 5145int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 5146 return ::vsnprintf(buf, count, format, args); 5147} 5148 5149// Is a (classpath) directory empty? 5150bool os::dir_is_empty(const char* path) { 5151 DIR *dir = NULL; 5152 struct dirent *ptr; 5153 5154 dir = opendir(path); 5155 if (dir == NULL) return true; 5156 5157 /* Scan the directory */ 5158 bool result = true; 5159 char buf[sizeof(struct dirent) + MAX_PATH]; 5160 while (result && (ptr = ::readdir(dir)) != NULL) { 5161 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5162 result = false; 5163 } 5164 } 5165 closedir(dir); 5166 return result; 5167} 5168 5169// This code originates from JDK's sysOpen and open64_w 5170// from src/solaris/hpi/src/system_md.c 5171 5172#ifndef O_DELETE 5173#define O_DELETE 0x10000 5174#endif 5175 5176// Open a file. Unlink the file immediately after open returns 5177// if the specified oflag has the O_DELETE flag set. 5178// O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c 5179 5180int os::open(const char *path, int oflag, int mode) { 5181 5182 if (strlen(path) > MAX_PATH - 1) { 5183 errno = ENAMETOOLONG; 5184 return -1; 5185 } 5186 int fd; 5187 int o_delete = (oflag & O_DELETE); 5188 oflag = oflag & ~O_DELETE; 5189 5190 fd = ::open64(path, oflag, mode); 5191 if (fd == -1) return -1; 5192 5193 //If the open succeeded, the file might still be a directory 5194 { 5195 struct stat64 buf64; 5196 int ret = ::fstat64(fd, &buf64); 5197 int st_mode = buf64.st_mode; 5198 5199 if (ret != -1) { 5200 if ((st_mode & S_IFMT) == S_IFDIR) { 5201 errno = EISDIR; 5202 ::close(fd); 5203 return -1; 5204 } 5205 } else { 5206 ::close(fd); 5207 return -1; 5208 } 5209 } 5210 5211 /* 5212 * All file descriptors that are opened in the JVM and not 5213 * specifically destined for a subprocess should have the 5214 * close-on-exec flag set. If we don't set it, then careless 3rd 5215 * party native code might fork and exec without closing all 5216 * appropriate file descriptors (e.g. as we do in closeDescriptors in 5217 * UNIXProcess.c), and this in turn might: 5218 * 5219 * - cause end-of-file to fail to be detected on some file 5220 * descriptors, resulting in mysterious hangs, or 5221 * 5222 * - might cause an fopen in the subprocess to fail on a system 5223 * suffering from bug 1085341. 5224 * 5225 * (Yes, the default setting of the close-on-exec flag is a Unix 5226 * design flaw) 5227 * 5228 * See: 5229 * 1085341: 32-bit stdio routines should support file descriptors >255 5230 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5231 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5232 */ 5233#ifdef FD_CLOEXEC 5234 { 5235 int flags = ::fcntl(fd, F_GETFD); 5236 if (flags != -1) 5237 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5238 } 5239#endif 5240 5241 if (o_delete != 0) { 5242 ::unlink(path); 5243 } 5244 return fd; 5245} 5246 5247 5248// create binary file, rewriting existing file if required 5249int os::create_binary_file(const char* path, bool rewrite_existing) { 5250 int oflags = O_WRONLY | O_CREAT; 5251 if (!rewrite_existing) { 5252 oflags |= O_EXCL; 5253 } 5254 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5255} 5256 5257// return current position of file pointer 5258jlong os::current_file_offset(int fd) { 5259 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5260} 5261 5262// move file pointer to the specified offset 5263jlong os::seek_to_file_offset(int fd, jlong offset) { 5264 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5265} 5266 5267// This code originates from JDK's sysAvailable 5268// from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5269 5270int os::available(int fd, jlong *bytes) { 5271 jlong cur, end; 5272 int mode; 5273 struct stat64 buf64; 5274 5275 if (::fstat64(fd, &buf64) >= 0) { 5276 mode = buf64.st_mode; 5277 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5278 /* 5279 * XXX: is the following call interruptible? If so, this might 5280 * need to go through the INTERRUPT_IO() wrapper as for other 5281 * blocking, interruptible calls in this file. 5282 */ 5283 int n; 5284 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5285 *bytes = n; 5286 return 1; 5287 } 5288 } 5289 } 5290 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5291 return 0; 5292 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5293 return 0; 5294 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5295 return 0; 5296 } 5297 *bytes = end - cur; 5298 return 1; 5299} 5300 5301int os::socket_available(int fd, jint *pbytes) { 5302 // Linux doc says EINTR not returned, unlike Solaris 5303 int ret = ::ioctl(fd, FIONREAD, pbytes); 5304 5305 //%% note ioctl can return 0 when successful, JVM_SocketAvailable 5306 // is expected to return 0 on failure and 1 on success to the jdk. 5307 return (ret < 0) ? 0 : 1; 5308} 5309 5310// Map a block of memory. 5311char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5312 char *addr, size_t bytes, bool read_only, 5313 bool allow_exec) { 5314 int prot; 5315 int flags = MAP_PRIVATE; 5316 5317 if (read_only) { 5318 prot = PROT_READ; 5319 } else { 5320 prot = PROT_READ | PROT_WRITE; 5321 } 5322 5323 if (allow_exec) { 5324 prot |= PROT_EXEC; 5325 } 5326 5327 if (addr != NULL) { 5328 flags |= MAP_FIXED; 5329 } 5330 5331 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5332 fd, file_offset); 5333 if (mapped_address == MAP_FAILED) { 5334 return NULL; 5335 } 5336 return mapped_address; 5337} 5338 5339 5340// Remap a block of memory. 5341char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5342 char *addr, size_t bytes, bool read_only, 5343 bool allow_exec) { 5344 // same as map_memory() on this OS 5345 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5346 allow_exec); 5347} 5348 5349 5350// Unmap a block of memory. 5351bool os::pd_unmap_memory(char* addr, size_t bytes) { 5352 return munmap(addr, bytes) == 0; 5353} 5354 5355static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5356 5357static clockid_t thread_cpu_clockid(Thread* thread) { 5358 pthread_t tid = thread->osthread()->pthread_id(); 5359 clockid_t clockid; 5360 5361 // Get thread clockid 5362 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5363 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5364 return clockid; 5365} 5366 5367// current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5368// are used by JVM M&M and JVMTI to get user+sys or user CPU time 5369// of a thread. 5370// 5371// current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5372// the fast estimate available on the platform. 5373 5374jlong os::current_thread_cpu_time() { 5375 if (os::Linux::supports_fast_thread_cpu_time()) { 5376 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5377 } else { 5378 // return user + sys since the cost is the same 5379 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5380 } 5381} 5382 5383jlong os::thread_cpu_time(Thread* thread) { 5384 // consistent with what current_thread_cpu_time() returns 5385 if (os::Linux::supports_fast_thread_cpu_time()) { 5386 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5387 } else { 5388 return slow_thread_cpu_time(thread, true /* user + sys */); 5389 } 5390} 5391 5392jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5393 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5394 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5395 } else { 5396 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5397 } 5398} 5399 5400jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5401 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5402 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5403 } else { 5404 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5405 } 5406} 5407 5408// 5409// -1 on error. 5410// 5411 5412static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5413 static bool proc_task_unchecked = true; 5414 static const char *proc_stat_path = "/proc/%d/stat"; 5415 pid_t tid = thread->osthread()->thread_id(); 5416 char *s; 5417 char stat[2048]; 5418 int statlen; 5419 char proc_name[64]; 5420 int count; 5421 long sys_time, user_time; 5422 char cdummy; 5423 int idummy; 5424 long ldummy; 5425 FILE *fp; 5426 5427 // The /proc/<tid>/stat aggregates per-process usage on 5428 // new Linux kernels 2.6+ where NPTL is supported. 5429 // The /proc/self/task/<tid>/stat still has the per-thread usage. 5430 // See bug 6328462. 5431 // There possibly can be cases where there is no directory 5432 // /proc/self/task, so we check its availability. 5433 if (proc_task_unchecked && os::Linux::is_NPTL()) { 5434 // This is executed only once 5435 proc_task_unchecked = false; 5436 fp = fopen("/proc/self/task", "r"); 5437 if (fp != NULL) { 5438 proc_stat_path = "/proc/self/task/%d/stat"; 5439 fclose(fp); 5440 } 5441 } 5442 5443 sprintf(proc_name, proc_stat_path, tid); 5444 fp = fopen(proc_name, "r"); 5445 if ( fp == NULL ) return -1; 5446 statlen = fread(stat, 1, 2047, fp); 5447 stat[statlen] = '\0'; 5448 fclose(fp); 5449 5450 // Skip pid and the command string. Note that we could be dealing with 5451 // weird command names, e.g. user could decide to rename java launcher 5452 // to "java 1.4.2 :)", then the stat file would look like 5453 // 1234 (java 1.4.2 :)) R ... ... 5454 // We don't really need to know the command string, just find the last 5455 // occurrence of ")" and then start parsing from there. See bug 4726580. 5456 s = strrchr(stat, ')'); 5457 if (s == NULL ) return -1; 5458 5459 // Skip blank chars 5460 do s++; while (isspace(*s)); 5461 5462 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5463 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5464 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5465 &user_time, &sys_time); 5466 if ( count != 13 ) return -1; 5467 if (user_sys_cpu_time) { 5468 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5469 } else { 5470 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5471 } 5472} 5473 5474void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5475 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5476 info_ptr->may_skip_backward = false; // elapsed time not wall time 5477 info_ptr->may_skip_forward = false; // elapsed time not wall time 5478 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5479} 5480 5481void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5482 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5483 info_ptr->may_skip_backward = false; // elapsed time not wall time 5484 info_ptr->may_skip_forward = false; // elapsed time not wall time 5485 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5486} 5487 5488bool os::is_thread_cpu_time_supported() { 5489 return true; 5490} 5491 5492// System loadavg support. Returns -1 if load average cannot be obtained. 5493// Linux doesn't yet have a (official) notion of processor sets, 5494// so just return the system wide load average. 5495int os::loadavg(double loadavg[], int nelem) { 5496 return ::getloadavg(loadavg, nelem); 5497} 5498 5499void os::pause() { 5500 char filename[MAX_PATH]; 5501 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5502 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5503 } else { 5504 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5505 } 5506 5507 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5508 if (fd != -1) { 5509 struct stat buf; 5510 ::close(fd); 5511 while (::stat(filename, &buf) == 0) { 5512 (void)::poll(NULL, 0, 100); 5513 } 5514 } else { 5515 jio_fprintf(stderr, 5516 "Could not open pause file '%s', continuing immediately.\n", filename); 5517 } 5518} 5519 5520 5521// Refer to the comments in os_solaris.cpp park-unpark. 5522// 5523// Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5524// hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5525// For specifics regarding the bug see GLIBC BUGID 261237 : 5526// http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5527// Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5528// will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5529// is used. (The simple C test-case provided in the GLIBC bug report manifests the 5530// hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5531// and monitorenter when we're using 1-0 locking. All those operations may result in 5532// calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5533// of libpthread avoids the problem, but isn't practical. 5534// 5535// Possible remedies: 5536// 5537// 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5538// This is palliative and probabilistic, however. If the thread is preempted 5539// between the call to compute_abstime() and pthread_cond_timedwait(), more 5540// than the minimum period may have passed, and the abstime may be stale (in the 5541// past) resultin in a hang. Using this technique reduces the odds of a hang 5542// but the JVM is still vulnerable, particularly on heavily loaded systems. 5543// 5544// 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5545// of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5546// NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5547// reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5548// thread. 5549// 5550// 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5551// that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5552// a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5553// This also works well. In fact it avoids kernel-level scalability impediments 5554// on certain platforms that don't handle lots of active pthread_cond_timedwait() 5555// timers in a graceful fashion. 5556// 5557// 4. When the abstime value is in the past it appears that control returns 5558// correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5559// Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5560// can avoid the problem by reinitializing the condvar -- by cond_destroy() 5561// followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5562// It may be possible to avoid reinitialization by checking the return 5563// value from pthread_cond_timedwait(). In addition to reinitializing the 5564// condvar we must establish the invariant that cond_signal() is only called 5565// within critical sections protected by the adjunct mutex. This prevents 5566// cond_signal() from "seeing" a condvar that's in the midst of being 5567// reinitialized or that is corrupt. Sadly, this invariant obviates the 5568// desirable signal-after-unlock optimization that avoids futile context switching. 5569// 5570// I'm also concerned that some versions of NTPL might allocate an auxilliary 5571// structure when a condvar is used or initialized. cond_destroy() would 5572// release the helper structure. Our reinitialize-after-timedwait fix 5573// put excessive stress on malloc/free and locks protecting the c-heap. 5574// 5575// We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5576// It may be possible to refine (4) by checking the kernel and NTPL verisons 5577// and only enabling the work-around for vulnerable environments. 5578 5579// utility to compute the abstime argument to timedwait: 5580// millis is the relative timeout time 5581// abstime will be the absolute timeout time 5582// TODO: replace compute_abstime() with unpackTime() 5583 5584static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5585 if (millis < 0) millis = 0; 5586 5587 jlong seconds = millis / 1000; 5588 millis %= 1000; 5589 if (seconds > 50000000) { // see man cond_timedwait(3T) 5590 seconds = 50000000; 5591 } 5592 5593 if (os::Linux::supports_monotonic_clock()) { 5594 struct timespec now; 5595 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5596 assert_status(status == 0, status, "clock_gettime"); 5597 abstime->tv_sec = now.tv_sec + seconds; 5598 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5599 if (nanos >= NANOSECS_PER_SEC) { 5600 abstime->tv_sec += 1; 5601 nanos -= NANOSECS_PER_SEC; 5602 } 5603 abstime->tv_nsec = nanos; 5604 } else { 5605 struct timeval now; 5606 int status = gettimeofday(&now, NULL); 5607 assert(status == 0, "gettimeofday"); 5608 abstime->tv_sec = now.tv_sec + seconds; 5609 long usec = now.tv_usec + millis * 1000; 5610 if (usec >= 1000000) { 5611 abstime->tv_sec += 1; 5612 usec -= 1000000; 5613 } 5614 abstime->tv_nsec = usec * 1000; 5615 } 5616 return abstime; 5617} 5618 5619 5620// Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 5621// Conceptually TryPark() should be equivalent to park(0). 5622 5623int os::PlatformEvent::TryPark() { 5624 for (;;) { 5625 const int v = _Event ; 5626 guarantee ((v == 0) || (v == 1), "invariant") ; 5627 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 5628 } 5629} 5630 5631void os::PlatformEvent::park() { // AKA "down()" 5632 // Invariant: Only the thread associated with the Event/PlatformEvent 5633 // may call park(). 5634 // TODO: assert that _Assoc != NULL or _Assoc == Self 5635 int v ; 5636 for (;;) { 5637 v = _Event ; 5638 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5639 } 5640 guarantee (v >= 0, "invariant") ; 5641 if (v == 0) { 5642 // Do this the hard way by blocking ... 5643 int status = pthread_mutex_lock(_mutex); 5644 assert_status(status == 0, status, "mutex_lock"); 5645 guarantee (_nParked == 0, "invariant") ; 5646 ++ _nParked ; 5647 while (_Event < 0) { 5648 status = pthread_cond_wait(_cond, _mutex); 5649 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5650 // Treat this the same as if the wait was interrupted 5651 if (status == ETIME) { status = EINTR; } 5652 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5653 } 5654 -- _nParked ; 5655 5656 _Event = 0 ; 5657 status = pthread_mutex_unlock(_mutex); 5658 assert_status(status == 0, status, "mutex_unlock"); 5659 // Paranoia to ensure our locked and lock-free paths interact 5660 // correctly with each other. 5661 OrderAccess::fence(); 5662 } 5663 guarantee (_Event >= 0, "invariant") ; 5664} 5665 5666int os::PlatformEvent::park(jlong millis) { 5667 guarantee (_nParked == 0, "invariant") ; 5668 5669 int v ; 5670 for (;;) { 5671 v = _Event ; 5672 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5673 } 5674 guarantee (v >= 0, "invariant") ; 5675 if (v != 0) return OS_OK ; 5676 5677 // We do this the hard way, by blocking the thread. 5678 // Consider enforcing a minimum timeout value. 5679 struct timespec abst; 5680 compute_abstime(&abst, millis); 5681 5682 int ret = OS_TIMEOUT; 5683 int status = pthread_mutex_lock(_mutex); 5684 assert_status(status == 0, status, "mutex_lock"); 5685 guarantee (_nParked == 0, "invariant") ; 5686 ++_nParked ; 5687 5688 // Object.wait(timo) will return because of 5689 // (a) notification 5690 // (b) timeout 5691 // (c) thread.interrupt 5692 // 5693 // Thread.interrupt and object.notify{All} both call Event::set. 5694 // That is, we treat thread.interrupt as a special case of notification. 5695 // The underlying Solaris implementation, cond_timedwait, admits 5696 // spurious/premature wakeups, but the JLS/JVM spec prevents the 5697 // JVM from making those visible to Java code. As such, we must 5698 // filter out spurious wakeups. We assume all ETIME returns are valid. 5699 // 5700 // TODO: properly differentiate simultaneous notify+interrupt. 5701 // In that case, we should propagate the notify to another waiter. 5702 5703 while (_Event < 0) { 5704 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5705 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5706 pthread_cond_destroy (_cond); 5707 pthread_cond_init (_cond, os::Linux::condAttr()) ; 5708 } 5709 assert_status(status == 0 || status == EINTR || 5710 status == ETIME || status == ETIMEDOUT, 5711 status, "cond_timedwait"); 5712 if (!FilterSpuriousWakeups) break ; // previous semantics 5713 if (status == ETIME || status == ETIMEDOUT) break ; 5714 // We consume and ignore EINTR and spurious wakeups. 5715 } 5716 --_nParked ; 5717 if (_Event >= 0) { 5718 ret = OS_OK; 5719 } 5720 _Event = 0 ; 5721 status = pthread_mutex_unlock(_mutex); 5722 assert_status(status == 0, status, "mutex_unlock"); 5723 assert (_nParked == 0, "invariant") ; 5724 // Paranoia to ensure our locked and lock-free paths interact 5725 // correctly with each other. 5726 OrderAccess::fence(); 5727 return ret; 5728} 5729 5730void os::PlatformEvent::unpark() { 5731 // Transitions for _Event: 5732 // 0 :=> 1 5733 // 1 :=> 1 5734 // -1 :=> either 0 or 1; must signal target thread 5735 // That is, we can safely transition _Event from -1 to either 5736 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back 5737 // unpark() calls. 5738 // See also: "Semaphores in Plan 9" by Mullender & Cox 5739 // 5740 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5741 // that it will take two back-to-back park() calls for the owning 5742 // thread to block. This has the benefit of forcing a spurious return 5743 // from the first park() call after an unpark() call which will help 5744 // shake out uses of park() and unpark() without condition variables. 5745 5746 if (Atomic::xchg(1, &_Event) >= 0) return; 5747 5748 // Wait for the thread associated with the event to vacate 5749 int status = pthread_mutex_lock(_mutex); 5750 assert_status(status == 0, status, "mutex_lock"); 5751 int AnyWaiters = _nParked; 5752 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5753 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5754 AnyWaiters = 0; 5755 pthread_cond_signal(_cond); 5756 } 5757 status = pthread_mutex_unlock(_mutex); 5758 assert_status(status == 0, status, "mutex_unlock"); 5759 if (AnyWaiters != 0) { 5760 status = pthread_cond_signal(_cond); 5761 assert_status(status == 0, status, "cond_signal"); 5762 } 5763 5764 // Note that we signal() _after dropping the lock for "immortal" Events. 5765 // This is safe and avoids a common class of futile wakeups. In rare 5766 // circumstances this can cause a thread to return prematurely from 5767 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 5768 // simply re-test the condition and re-park itself. 5769} 5770 5771 5772// JSR166 5773// ------------------------------------------------------- 5774 5775/* 5776 * The solaris and linux implementations of park/unpark are fairly 5777 * conservative for now, but can be improved. They currently use a 5778 * mutex/condvar pair, plus a a count. 5779 * Park decrements count if > 0, else does a condvar wait. Unpark 5780 * sets count to 1 and signals condvar. Only one thread ever waits 5781 * on the condvar. Contention seen when trying to park implies that someone 5782 * is unparking you, so don't wait. And spurious returns are fine, so there 5783 * is no need to track notifications. 5784 */ 5785 5786#define MAX_SECS 100000000 5787/* 5788 * This code is common to linux and solaris and will be moved to a 5789 * common place in dolphin. 5790 * 5791 * The passed in time value is either a relative time in nanoseconds 5792 * or an absolute time in milliseconds. Either way it has to be unpacked 5793 * into suitable seconds and nanoseconds components and stored in the 5794 * given timespec structure. 5795 * Given time is a 64-bit value and the time_t used in the timespec is only 5796 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 5797 * overflow if times way in the future are given. Further on Solaris versions 5798 * prior to 10 there is a restriction (see cond_timedwait) that the specified 5799 * number of seconds, in abstime, is less than current_time + 100,000,000. 5800 * As it will be 28 years before "now + 100000000" will overflow we can 5801 * ignore overflow and just impose a hard-limit on seconds using the value 5802 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 5803 * years from "now". 5804 */ 5805 5806static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5807 assert (time > 0, "convertTime"); 5808 time_t max_secs = 0; 5809 5810 if (!os::Linux::supports_monotonic_clock() || isAbsolute) { 5811 struct timeval now; 5812 int status = gettimeofday(&now, NULL); 5813 assert(status == 0, "gettimeofday"); 5814 5815 max_secs = now.tv_sec + MAX_SECS; 5816 5817 if (isAbsolute) { 5818 jlong secs = time / 1000; 5819 if (secs > max_secs) { 5820 absTime->tv_sec = max_secs; 5821 } else { 5822 absTime->tv_sec = secs; 5823 } 5824 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5825 } else { 5826 jlong secs = time / NANOSECS_PER_SEC; 5827 if (secs >= MAX_SECS) { 5828 absTime->tv_sec = max_secs; 5829 absTime->tv_nsec = 0; 5830 } else { 5831 absTime->tv_sec = now.tv_sec + secs; 5832 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5833 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5834 absTime->tv_nsec -= NANOSECS_PER_SEC; 5835 ++absTime->tv_sec; // note: this must be <= max_secs 5836 } 5837 } 5838 } 5839 } else { 5840 // must be relative using monotonic clock 5841 struct timespec now; 5842 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5843 assert_status(status == 0, status, "clock_gettime"); 5844 max_secs = now.tv_sec + MAX_SECS; 5845 jlong secs = time / NANOSECS_PER_SEC; 5846 if (secs >= MAX_SECS) { 5847 absTime->tv_sec = max_secs; 5848 absTime->tv_nsec = 0; 5849 } else { 5850 absTime->tv_sec = now.tv_sec + secs; 5851 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5852 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5853 absTime->tv_nsec -= NANOSECS_PER_SEC; 5854 ++absTime->tv_sec; // note: this must be <= max_secs 5855 } 5856 } 5857 } 5858 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5859 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5860 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5861 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5862} 5863 5864void Parker::park(bool isAbsolute, jlong time) { 5865 // Ideally we'd do something useful while spinning, such 5866 // as calling unpackTime(). 5867 5868 // Optional fast-path check: 5869 // Return immediately if a permit is available. 5870 // We depend on Atomic::xchg() having full barrier semantics 5871 // since we are doing a lock-free update to _counter. 5872 if (Atomic::xchg(0, &_counter) > 0) return; 5873 5874 Thread* thread = Thread::current(); 5875 assert(thread->is_Java_thread(), "Must be JavaThread"); 5876 JavaThread *jt = (JavaThread *)thread; 5877 5878 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5879 // Check interrupt before trying to wait 5880 if (Thread::is_interrupted(thread, false)) { 5881 return; 5882 } 5883 5884 // Next, demultiplex/decode time arguments 5885 timespec absTime; 5886 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all 5887 return; 5888 } 5889 if (time > 0) { 5890 unpackTime(&absTime, isAbsolute, time); 5891 } 5892 5893 5894 // Enter safepoint region 5895 // Beware of deadlocks such as 6317397. 5896 // The per-thread Parker:: mutex is a classic leaf-lock. 5897 // In particular a thread must never block on the Threads_lock while 5898 // holding the Parker:: mutex. If safepoints are pending both the 5899 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5900 ThreadBlockInVM tbivm(jt); 5901 5902 // Don't wait if cannot get lock since interference arises from 5903 // unblocking. Also. check interrupt before trying wait 5904 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5905 return; 5906 } 5907 5908 int status ; 5909 if (_counter > 0) { // no wait needed 5910 _counter = 0; 5911 status = pthread_mutex_unlock(_mutex); 5912 assert (status == 0, "invariant") ; 5913 // Paranoia to ensure our locked and lock-free paths interact 5914 // correctly with each other and Java-level accesses. 5915 OrderAccess::fence(); 5916 return; 5917 } 5918 5919#ifdef ASSERT 5920 // Don't catch signals while blocked; let the running threads have the signals. 5921 // (This allows a debugger to break into the running thread.) 5922 sigset_t oldsigs; 5923 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5924 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5925#endif 5926 5927 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5928 jt->set_suspend_equivalent(); 5929 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5930 5931 assert(_cur_index == -1, "invariant"); 5932 if (time == 0) { 5933 _cur_index = REL_INDEX; // arbitrary choice when not timed 5934 status = pthread_cond_wait (&_cond[_cur_index], _mutex) ; 5935 } else { 5936 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5937 status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ; 5938 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5939 pthread_cond_destroy (&_cond[_cur_index]) ; 5940 pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5941 } 5942 } 5943 _cur_index = -1; 5944 assert_status(status == 0 || status == EINTR || 5945 status == ETIME || status == ETIMEDOUT, 5946 status, "cond_timedwait"); 5947 5948#ifdef ASSERT 5949 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5950#endif 5951 5952 _counter = 0 ; 5953 status = pthread_mutex_unlock(_mutex) ; 5954 assert_status(status == 0, status, "invariant") ; 5955 // Paranoia to ensure our locked and lock-free paths interact 5956 // correctly with each other and Java-level accesses. 5957 OrderAccess::fence(); 5958 5959 // If externally suspended while waiting, re-suspend 5960 if (jt->handle_special_suspend_equivalent_condition()) { 5961 jt->java_suspend_self(); 5962 } 5963} 5964 5965void Parker::unpark() { 5966 int s, status ; 5967 status = pthread_mutex_lock(_mutex); 5968 assert (status == 0, "invariant") ; 5969 s = _counter; 5970 _counter = 1; 5971 if (s < 1) { 5972 // thread might be parked 5973 if (_cur_index != -1) { 5974 // thread is definitely parked 5975 if (WorkAroundNPTLTimedWaitHang) { 5976 status = pthread_cond_signal (&_cond[_cur_index]); 5977 assert (status == 0, "invariant"); 5978 status = pthread_mutex_unlock(_mutex); 5979 assert (status == 0, "invariant"); 5980 } else { 5981 status = pthread_mutex_unlock(_mutex); 5982 assert (status == 0, "invariant"); 5983 status = pthread_cond_signal (&_cond[_cur_index]); 5984 assert (status == 0, "invariant"); 5985 } 5986 } else { 5987 pthread_mutex_unlock(_mutex); 5988 assert (status == 0, "invariant") ; 5989 } 5990 } else { 5991 pthread_mutex_unlock(_mutex); 5992 assert (status == 0, "invariant") ; 5993 } 5994} 5995 5996 5997extern char** environ; 5998 5999#ifndef __NR_fork 6000#define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 6001#endif 6002 6003#ifndef __NR_execve 6004#define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 6005#endif 6006 6007// Run the specified command in a separate process. Return its exit value, 6008// or -1 on failure (e.g. can't fork a new process). 6009// Unlike system(), this function can be called from signal handler. It 6010// doesn't block SIGINT et al. 6011int os::fork_and_exec(char* cmd) { 6012 const char * argv[4] = {"sh", "-c", cmd, NULL}; 6013 6014 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 6015 // pthread_atfork handlers and reset pthread library. All we need is a 6016 // separate process to execve. Make a direct syscall to fork process. 6017 // On IA64 there's no fork syscall, we have to use fork() and hope for 6018 // the best... 6019 pid_t pid = NOT_IA64(syscall(__NR_fork);) 6020 IA64_ONLY(fork();) 6021 6022 if (pid < 0) { 6023 // fork failed 6024 return -1; 6025 6026 } else if (pid == 0) { 6027 // child process 6028 6029 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 6030 // first to kill every thread on the thread list. Because this list is 6031 // not reset by fork() (see notes above), execve() will instead kill 6032 // every thread in the parent process. We know this is the only thread 6033 // in the new process, so make a system call directly. 6034 // IA64 should use normal execve() from glibc to match the glibc fork() 6035 // above. 6036 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 6037 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 6038 6039 // execve failed 6040 _exit(-1); 6041 6042 } else { 6043 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 6044 // care about the actual exit code, for now. 6045 6046 int status; 6047 6048 // Wait for the child process to exit. This returns immediately if 6049 // the child has already exited. */ 6050 while (waitpid(pid, &status, 0) < 0) { 6051 switch (errno) { 6052 case ECHILD: return 0; 6053 case EINTR: break; 6054 default: return -1; 6055 } 6056 } 6057 6058 if (WIFEXITED(status)) { 6059 // The child exited normally; get its exit code. 6060 return WEXITSTATUS(status); 6061 } else if (WIFSIGNALED(status)) { 6062 // The child exited because of a signal 6063 // The best value to return is 0x80 + signal number, 6064 // because that is what all Unix shells do, and because 6065 // it allows callers to distinguish between process exit and 6066 // process death by signal. 6067 return 0x80 + WTERMSIG(status); 6068 } else { 6069 // Unknown exit code; pass it through 6070 return status; 6071 } 6072 } 6073} 6074 6075// is_headless_jre() 6076// 6077// Test for the existence of xawt/libmawt.so or libawt_xawt.so 6078// in order to report if we are running in a headless jre 6079// 6080// Since JDK8 xawt/libmawt.so was moved into the same directory 6081// as libawt.so, and renamed libawt_xawt.so 6082// 6083bool os::is_headless_jre() { 6084 struct stat statbuf; 6085 char buf[MAXPATHLEN]; 6086 char libmawtpath[MAXPATHLEN]; 6087 const char *xawtstr = "/xawt/libmawt.so"; 6088 const char *new_xawtstr = "/libawt_xawt.so"; 6089 char *p; 6090 6091 // Get path to libjvm.so 6092 os::jvm_path(buf, sizeof(buf)); 6093 6094 // Get rid of libjvm.so 6095 p = strrchr(buf, '/'); 6096 if (p == NULL) return false; 6097 else *p = '\0'; 6098 6099 // Get rid of client or server 6100 p = strrchr(buf, '/'); 6101 if (p == NULL) return false; 6102 else *p = '\0'; 6103 6104 // check xawt/libmawt.so 6105 strcpy(libmawtpath, buf); 6106 strcat(libmawtpath, xawtstr); 6107 if (::stat(libmawtpath, &statbuf) == 0) return false; 6108 6109 // check libawt_xawt.so 6110 strcpy(libmawtpath, buf); 6111 strcat(libmawtpath, new_xawtstr); 6112 if (::stat(libmawtpath, &statbuf) == 0) return false; 6113 6114 return true; 6115} 6116 6117// Get the default path to the core file 6118// Returns the length of the string 6119int os::get_core_path(char* buffer, size_t bufferSize) { 6120 const char* p = get_current_directory(buffer, bufferSize); 6121 6122 if (p == NULL) { 6123 assert(p != NULL, "failed to get current directory"); 6124 return 0; 6125 } 6126 6127 return strlen(buffer); 6128} 6129 6130#ifdef JAVASE_EMBEDDED 6131// 6132// A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory. 6133// 6134MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL; 6135 6136// ctor 6137// 6138MemNotifyThread::MemNotifyThread(int fd): Thread() { 6139 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread"); 6140 _fd = fd; 6141 6142 if (os::create_thread(this, os::os_thread)) { 6143 _memnotify_thread = this; 6144 os::set_priority(this, NearMaxPriority); 6145 os::start_thread(this); 6146 } 6147} 6148 6149// Where all the work gets done 6150// 6151void MemNotifyThread::run() { 6152 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread"); 6153 6154 // Set up the select arguments 6155 fd_set rfds; 6156 if (_fd != -1) { 6157 FD_ZERO(&rfds); 6158 FD_SET(_fd, &rfds); 6159 } 6160 6161 // Now wait for the mem_notify device to wake up 6162 while (1) { 6163 // Wait for the mem_notify device to signal us.. 6164 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL); 6165 if (rc == -1) { 6166 perror("select!\n"); 6167 break; 6168 } else if (rc) { 6169 //ssize_t free_before = os::available_memory(); 6170 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024); 6171 6172 // The kernel is telling us there is not much memory left... 6173 // try to do something about that 6174 6175 // If we are not already in a GC, try one. 6176 if (!Universe::heap()->is_gc_active()) { 6177 Universe::heap()->collect(GCCause::_allocation_failure); 6178 6179 //ssize_t free_after = os::available_memory(); 6180 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024); 6181 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024); 6182 } 6183 // We might want to do something like the following if we find the GC's are not helping... 6184 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true); 6185 } 6186 } 6187} 6188 6189// 6190// See if the /dev/mem_notify device exists, and if so, start a thread to monitor it. 6191// 6192void MemNotifyThread::start() { 6193 int fd; 6194 fd = open ("/dev/mem_notify", O_RDONLY, 0); 6195 if (fd < 0) { 6196 return; 6197 } 6198 6199 if (memnotify_thread() == NULL) { 6200 new MemNotifyThread(fd); 6201 } 6202} 6203 6204#endif // JAVASE_EMBEDDED 6205 6206 6207/////////////// Unit tests /////////////// 6208 6209#ifndef PRODUCT 6210 6211#define test_log(...) \ 6212 do {\ 6213 if (VerboseInternalVMTests) { \ 6214 tty->print_cr(__VA_ARGS__); \ 6215 tty->flush(); \ 6216 }\ 6217 } while (false) 6218 6219class TestReserveMemorySpecial : AllStatic { 6220 public: 6221 static void small_page_write(void* addr, size_t size) { 6222 size_t page_size = os::vm_page_size(); 6223 6224 char* end = (char*)addr + size; 6225 for (char* p = (char*)addr; p < end; p += page_size) { 6226 *p = 1; 6227 } 6228 } 6229 6230 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6231 if (!UseHugeTLBFS) { 6232 return; 6233 } 6234 6235 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6236 6237 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6238 6239 if (addr != NULL) { 6240 small_page_write(addr, size); 6241 6242 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6243 } 6244 } 6245 6246 static void test_reserve_memory_special_huge_tlbfs_only() { 6247 if (!UseHugeTLBFS) { 6248 return; 6249 } 6250 6251 size_t lp = os::large_page_size(); 6252 6253 for (size_t size = lp; size <= lp * 10; size += lp) { 6254 test_reserve_memory_special_huge_tlbfs_only(size); 6255 } 6256 } 6257 6258 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) { 6259 if (!UseHugeTLBFS) { 6260 return; 6261 } 6262 6263 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")", 6264 size, alignment); 6265 6266 assert(size >= os::large_page_size(), "Incorrect input to test"); 6267 6268 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6269 6270 if (addr != NULL) { 6271 small_page_write(addr, size); 6272 6273 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6274 } 6275 } 6276 6277 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) { 6278 size_t lp = os::large_page_size(); 6279 size_t ag = os::vm_allocation_granularity(); 6280 6281 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6282 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment); 6283 } 6284 } 6285 6286 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6287 size_t lp = os::large_page_size(); 6288 size_t ag = os::vm_allocation_granularity(); 6289 6290 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp); 6291 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag); 6292 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2); 6293 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2); 6294 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag); 6295 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag); 6296 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2); 6297 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10); 6298 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2); 6299 } 6300 6301 static void test_reserve_memory_special_huge_tlbfs() { 6302 if (!UseHugeTLBFS) { 6303 return; 6304 } 6305 6306 test_reserve_memory_special_huge_tlbfs_only(); 6307 test_reserve_memory_special_huge_tlbfs_mixed(); 6308 } 6309 6310 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6311 if (!UseSHM) { 6312 return; 6313 } 6314 6315 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6316 6317 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6318 6319 if (addr != NULL) { 6320 assert(is_ptr_aligned(addr, alignment), "Check"); 6321 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6322 6323 small_page_write(addr, size); 6324 6325 os::Linux::release_memory_special_shm(addr, size); 6326 } 6327 } 6328 6329 static void test_reserve_memory_special_shm() { 6330 size_t lp = os::large_page_size(); 6331 size_t ag = os::vm_allocation_granularity(); 6332 6333 for (size_t size = ag; size < lp * 3; size += ag) { 6334 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6335 test_reserve_memory_special_shm(size, alignment); 6336 } 6337 } 6338 } 6339 6340 static void test() { 6341 test_reserve_memory_special_huge_tlbfs(); 6342 test_reserve_memory_special_shm(); 6343 } 6344}; 6345 6346void TestReserveMemorySpecial_test() { 6347 TestReserveMemorySpecial::test(); 6348} 6349 6350#endif 6351