1 /* 2 * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 // no precompiled headers 26 #include "classfile/classLoader.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "code/icBuffer.hpp" 30 #include "code/vtableStubs.hpp" 31 #include "compiler/compileBroker.hpp" 32 #include "compiler/disassembler.hpp" 33 #include "interpreter/interpreter.hpp" 34 #include "jvm_linux.h" 35 #include "memory/allocation.inline.hpp" 36 #include "memory/filemap.hpp" 37 #include "mutex_linux.inline.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "os_share_linux.hpp" 40 #include "prims/jniFastGetField.hpp" 41 #include "prims/jvm.h" 42 #include "prims/jvm_misc.hpp" 43 #include "runtime/arguments.hpp" 44 #include "runtime/extendedPC.hpp" 45 #include "runtime/globals.hpp" 46 #include "runtime/interfaceSupport.hpp" 47 #include "runtime/init.hpp" 48 #include "runtime/java.hpp" 49 #include "runtime/javaCalls.hpp" 50 #include "runtime/mutexLocker.hpp" 51 #include "runtime/objectMonitor.hpp" 52 #include "runtime/osThread.hpp" 53 #include "runtime/perfMemory.hpp" 54 #include "runtime/sharedRuntime.hpp" 55 #include "runtime/statSampler.hpp" 56 #include "runtime/stubRoutines.hpp" 57 #include "runtime/thread.inline.hpp" 58 #include "runtime/threadCritical.hpp" 59 #include "runtime/timer.hpp" 60 #include "services/attachListener.hpp" 61 #include "services/memTracker.hpp" 62 #include "services/runtimeService.hpp" 63 #include "utilities/decoder.hpp" 64 #include "utilities/defaultStream.hpp" 65 #include "utilities/events.hpp" 66 #include "utilities/elfFile.hpp" 67 #include "utilities/growableArray.hpp" 68 #include "utilities/vmError.hpp" 69 70 // put OS-includes here 71 # include <sys/types.h> 72 # include <sys/mman.h> 73 # include <sys/stat.h> 74 # include <sys/select.h> 75 # include <pthread.h> 76 # include <signal.h> 77 # include <errno.h> 78 # include <dlfcn.h> 79 # include <stdio.h> 80 # include <unistd.h> 81 # include <sys/resource.h> 82 # include <pthread.h> 83 # include <sys/stat.h> 84 # include <sys/time.h> 85 # include <sys/times.h> 86 # include <sys/utsname.h> 87 # include <sys/socket.h> 88 # include <sys/wait.h> 89 # include <pwd.h> 90 # include <poll.h> 91 # include <semaphore.h> 92 # include <fcntl.h> 93 # include <string.h> 94 # include <syscall.h> 95 # include <sys/sysinfo.h> 96 # include <gnu/libc-version.h> 97 # include <sys/ipc.h> 98 # include <sys/shm.h> 99 # include <link.h> 100 # include <stdint.h> 101 # include <inttypes.h> 102 # include <sys/ioctl.h> 103 104 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling 105 // getrusage() is prepared to handle the associated failure. 106 #ifndef RUSAGE_THREAD 107 #define RUSAGE_THREAD (1) /* only the calling thread */ 108 #endif 109 110 #define MAX_PATH (2 * K) 111 112 // for timer info max values which include all bits 113 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 114 115 #define LARGEPAGES_BIT (1 << 6) 116 //////////////////////////////////////////////////////////////////////////////// 117 // global variables 118 julong os::Linux::_physical_memory = 0; 119 120 address os::Linux::_initial_thread_stack_bottom = NULL; 121 uintptr_t os::Linux::_initial_thread_stack_size = 0; 122 123 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 124 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 125 Mutex* os::Linux::_createThread_lock = NULL; 126 pthread_t os::Linux::_main_thread; 127 int os::Linux::_page_size = -1; 128 const int os::Linux::_vm_default_page_size = (8 * K); 129 bool os::Linux::_is_floating_stack = false; 130 bool os::Linux::_is_NPTL = false; 131 bool os::Linux::_supports_fast_thread_cpu_time = false; 132 const char * os::Linux::_glibc_version = NULL; 133 const char * os::Linux::_libpthread_version = NULL; 134 pthread_condattr_t os::Linux::_condattr[1]; 135 136 static jlong initial_time_count=0; 137 138 static int clock_tics_per_sec = 100; 139 140 // For diagnostics to print a message once. see run_periodic_checks 141 static sigset_t check_signal_done; 142 static bool check_signals = true; 143 144 static 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 */ 149 static int SR_signum = SIGUSR2; 150 sigset_t SR_sigset; 151 152 /* Used to protect dlsym() calls */ 153 static pthread_mutex_t dl_mutex; 154 155 // Declarations 156 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time); 157 158 #ifdef JAVASE_EMBEDDED 159 class 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 188 189 static int SR_initialize(); 190 191 julong os::available_memory() { 192 return Linux::available_memory(); 193 } 194 195 julong 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 } 202 203 julong os::physical_memory() { 204 return Linux::physical_memory(); 205 } 206 207 //////////////////////////////////////////////////////////////////////////////// 208 // environment support 209 210 bool 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. 222 223 bool 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) 251 static char cpu_arch[] = ZERO_LIBARCH; 252 #elif defined(IA64) 253 static char cpu_arch[] = "ia64"; 254 #elif defined(IA32) 255 static char cpu_arch[] = "i386"; 256 #elif defined(AMD64) 257 static char cpu_arch[] = "amd64"; 258 #elif defined(ARM) 259 static char cpu_arch[] = "arm"; 260 #elif defined(PPC32) 261 static char cpu_arch[] = "ppc"; 262 #elif defined(PPC64) 263 static char cpu_arch[] = "ppc64"; 264 #elif defined(SPARC) 265 # ifdef _LP64 266 static char cpu_arch[] = "sparcv9"; 267 # else 268 static char cpu_arch[] = "sparc"; 269 # endif 270 #else 271 #error Add appropriate cpu_arch setting 272 #endif 273 274 275 // pid_t gettid() 276 // 277 // Returns the kernel thread id of the currently running thread. Kernel 278 // thread id is used to access /proc. 279 // 280 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 281 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 282 // 283 pid_t os::Linux::gettid() { 284 int rslt = syscall(SYS_gettid); 285 if (rslt == -1) { 286 // old kernel, no NPTL support 287 return getpid(); 288 } else { 289 return (pid_t)rslt; 290 } 291 } 292 293 // Most versions of linux have a bug where the number of processors are 294 // determined by looking at the /proc file system. In a chroot environment, 295 // the system call returns 1. This causes the VM to act as if it is 296 // a single processor and elide locking (see is_MP() call). 297 static bool unsafe_chroot_detected = false; 298 static const char *unstable_chroot_error = "/proc file system not found.\n" 299 "Java may be unstable running multithreaded in a chroot " 300 "environment on Linux when /proc filesystem is not mounted."; 301 302 void os::Linux::initialize_system_info() { 303 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 304 if (processor_count() == 1) { 305 pid_t pid = os::Linux::gettid(); 306 char fname[32]; 307 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 308 FILE *fp = fopen(fname, "r"); 309 if (fp == NULL) { 310 unsafe_chroot_detected = true; 311 } else { 312 fclose(fp); 313 } 314 } 315 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 316 assert(processor_count() > 0, "linux error"); 317 } 318 319 void os::init_system_properties_values() { 320 // The next steps are taken in the product version: 321 // 322 // Obtain the JAVA_HOME value from the location of libjvm.so. 323 // This library should be located at: 324 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 325 // 326 // If "/jre/lib/" appears at the right place in the path, then we 327 // assume libjvm.so is installed in a JDK and we use this path. 328 // 329 // Otherwise exit with message: "Could not create the Java virtual machine." 330 // 331 // The following extra steps are taken in the debugging version: 332 // 333 // If "/jre/lib/" does NOT appear at the right place in the path 334 // instead of exit check for $JAVA_HOME environment variable. 335 // 336 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 337 // then we append a fake suffix "hotspot/libjvm.so" to this path so 338 // it looks like libjvm.so is installed there 339 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 340 // 341 // Otherwise exit. 342 // 343 // Important note: if the location of libjvm.so changes this 344 // code needs to be changed accordingly. 345 346 /* 347 * See ld(1): 348 * The linker uses the following search paths to locate required 349 * shared libraries: 350 * 1: ... 351 * ... 352 * 7: The default directories, normally /lib and /usr/lib. 353 */ 354 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 355 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 356 #else 357 #define DEFAULT_LIBPATH "/lib:/usr/lib" 358 #endif 359 360 #define EXTENSIONS_DIR "/lib/ext" 361 #define ENDORSED_DIR "/lib/endorsed" 362 #define REG_DIR "/usr/java/packages" 363 364 /* sysclasspath, java_home, dll_dir */ 365 { 366 char *pslash; 367 char buf[MAXPATHLEN]; 368 os::jvm_path(buf, sizeof(buf)); 369 370 // Found the full path to libjvm.so. 371 // Now cut the path to <java_home>/jre if we can. 372 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */ 373 pslash = strrchr(buf, '/'); 374 if (pslash != NULL) { 375 *pslash = '\0'; /* get rid of /{client|server|hotspot} */ 376 } 377 Arguments::set_dll_dir(buf); 378 379 if (pslash != NULL) { 380 pslash = strrchr(buf, '/'); 381 if (pslash != NULL) { 382 *pslash = '\0'; /* get rid of /<arch> */ 383 pslash = strrchr(buf, '/'); 384 if (pslash != NULL) { 385 *pslash = '\0'; /* get rid of /lib */ 386 } 387 } 388 } 389 Arguments::set_java_home(buf); 390 391 if (!set_boot_path('/', ':')) { 392 return; 393 } 394 } 395 396 /* 397 * Where to look for native libraries 398 * 399 * Note: Due to a legacy implementation, most of the library path 400 * is set in the launcher. This was to accomodate linking restrictions 401 * on legacy Linux implementations (which are no longer supported). 402 * Eventually, all the library path setting will be done here. 403 * 404 * However, to prevent the proliferation of improperly built native 405 * libraries, the new path component /usr/java/packages is added here. 406 * Eventually, all the library path setting will be done here. 407 */ 408 { 409 char *ld_library_path; 410 411 /* 412 * Construct the invariant part of ld_library_path. Note that the 413 * space for the colon and the trailing null are provided by the 414 * nulls included by the sizeof operator (so actually we allocate 415 * a byte more than necessary). 416 */ 417 ld_library_path = (char *)NEW_C_HEAP_ARRAY(char, sizeof(REG_DIR) + sizeof("/lib/") + 418 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH), mtInternal); 419 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch); 420 421 /* 422 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It 423 * should always exist (until the legacy problem cited above is 424 * addressed). 425 */ 426 char *v = ::getenv("LD_LIBRARY_PATH"); 427 if (v != NULL) { 428 char *t = ld_library_path; 429 /* That's +1 for the colon and +1 for the trailing '\0' */ 430 ld_library_path = (char *)NEW_C_HEAP_ARRAY(char, strlen(v) + 1 + strlen(t) + 1, mtInternal); 431 sprintf(ld_library_path, "%s:%s", v, t); 432 FREE_C_HEAP_ARRAY(char, t, mtInternal); 433 } 434 Arguments::set_library_path(ld_library_path); 435 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal); 436 } 437 438 /* 439 * Buffer that fits both sprintfs. 440 * Note that the space for the colon and the trailing null are provided 441 * by the nulls included by the sizeof operator (so actually one byte more 442 * than necessary is allocated). 443 */ 444 char buf[MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR) + sizeof(ENDORSED_DIR)]; 445 446 /* Extensions directories. */ 447 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR, Arguments::get_java_home()); 448 Arguments::set_ext_dirs(buf); 449 450 /* Endorsed standards default directory. */ 451 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 452 Arguments::set_endorsed_dirs(buf); 453 454 #undef EXTENSIONS_DIR 455 #undef ENDORSED_DIR 456 } 457 458 //////////////////////////////////////////////////////////////////////////////// 459 // breakpoint support 460 461 void os::breakpoint() { 462 BREAKPOINT; 463 } 464 465 extern "C" void breakpoint() { 466 // use debugger to set breakpoint here 467 } 468 469 //////////////////////////////////////////////////////////////////////////////// 470 // signal support 471 472 debug_only(static bool signal_sets_initialized = false); 473 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 474 475 bool os::Linux::is_sig_ignored(int sig) { 476 struct sigaction oact; 477 sigaction(sig, (struct sigaction*)NULL, &oact); 478 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 479 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 480 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 481 return true; 482 else 483 return false; 484 } 485 486 void os::Linux::signal_sets_init() { 487 // Should also have an assertion stating we are still single-threaded. 488 assert(!signal_sets_initialized, "Already initialized"); 489 // Fill in signals that are necessarily unblocked for all threads in 490 // the VM. Currently, we unblock the following signals: 491 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 492 // by -Xrs (=ReduceSignalUsage)); 493 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 494 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 495 // the dispositions or masks wrt these signals. 496 // Programs embedding the VM that want to use the above signals for their 497 // own purposes must, at this time, use the "-Xrs" option to prevent 498 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 499 // (See bug 4345157, and other related bugs). 500 // In reality, though, unblocking these signals is really a nop, since 501 // these signals are not blocked by default. 502 sigemptyset(&unblocked_sigs); 503 sigemptyset(&allowdebug_blocked_sigs); 504 sigaddset(&unblocked_sigs, SIGILL); 505 sigaddset(&unblocked_sigs, SIGSEGV); 506 sigaddset(&unblocked_sigs, SIGBUS); 507 sigaddset(&unblocked_sigs, SIGFPE); 508 #if defined(PPC64) 509 sigaddset(&unblocked_sigs, SIGTRAP); 510 #endif 511 sigaddset(&unblocked_sigs, SR_signum); 512 513 if (!ReduceSignalUsage) { 514 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 515 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 516 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 517 } 518 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 519 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 520 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 521 } 522 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 523 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 524 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 525 } 526 } 527 // Fill in signals that are blocked by all but the VM thread. 528 sigemptyset(&vm_sigs); 529 if (!ReduceSignalUsage) 530 sigaddset(&vm_sigs, BREAK_SIGNAL); 531 debug_only(signal_sets_initialized = true); 532 533 } 534 535 // These are signals that are unblocked while a thread is running Java. 536 // (For some reason, they get blocked by default.) 537 sigset_t* os::Linux::unblocked_signals() { 538 assert(signal_sets_initialized, "Not initialized"); 539 return &unblocked_sigs; 540 } 541 542 // These are the signals that are blocked while a (non-VM) thread is 543 // running Java. Only the VM thread handles these signals. 544 sigset_t* os::Linux::vm_signals() { 545 assert(signal_sets_initialized, "Not initialized"); 546 return &vm_sigs; 547 } 548 549 // These are signals that are blocked during cond_wait to allow debugger in 550 sigset_t* os::Linux::allowdebug_blocked_signals() { 551 assert(signal_sets_initialized, "Not initialized"); 552 return &allowdebug_blocked_sigs; 553 } 554 555 void os::Linux::hotspot_sigmask(Thread* thread) { 556 557 //Save caller's signal mask before setting VM signal mask 558 sigset_t caller_sigmask; 559 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 560 561 OSThread* osthread = thread->osthread(); 562 osthread->set_caller_sigmask(caller_sigmask); 563 564 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 565 566 if (!ReduceSignalUsage) { 567 if (thread->is_VM_thread()) { 568 // Only the VM thread handles BREAK_SIGNAL ... 569 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 570 } else { 571 // ... all other threads block BREAK_SIGNAL 572 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 573 } 574 } 575 } 576 577 ////////////////////////////////////////////////////////////////////////////// 578 // detecting pthread library 579 580 void os::Linux::libpthread_init() { 581 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 582 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 583 // generic name for earlier versions. 584 // Define macros here so we can build HotSpot on old systems. 585 # ifndef _CS_GNU_LIBC_VERSION 586 # define _CS_GNU_LIBC_VERSION 2 587 # endif 588 # ifndef _CS_GNU_LIBPTHREAD_VERSION 589 # define _CS_GNU_LIBPTHREAD_VERSION 3 590 # endif 591 592 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 593 if (n > 0) { 594 char *str = (char *)malloc(n, mtInternal); 595 confstr(_CS_GNU_LIBC_VERSION, str, n); 596 os::Linux::set_glibc_version(str); 597 } else { 598 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 599 static char _gnu_libc_version[32]; 600 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 601 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 602 os::Linux::set_glibc_version(_gnu_libc_version); 603 } 604 605 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 606 if (n > 0) { 607 char *str = (char *)malloc(n, mtInternal); 608 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 609 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 610 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 611 // is the case. LinuxThreads has a hard limit on max number of threads. 612 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 613 // On the other hand, NPTL does not have such a limit, sysconf() 614 // will return -1 and errno is not changed. Check if it is really NPTL. 615 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 616 strstr(str, "NPTL") && 617 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 618 free(str); 619 os::Linux::set_libpthread_version("linuxthreads"); 620 } else { 621 os::Linux::set_libpthread_version(str); 622 } 623 } else { 624 // glibc before 2.3.2 only has LinuxThreads. 625 os::Linux::set_libpthread_version("linuxthreads"); 626 } 627 628 if (strstr(libpthread_version(), "NPTL")) { 629 os::Linux::set_is_NPTL(); 630 } else { 631 os::Linux::set_is_LinuxThreads(); 632 } 633 634 // LinuxThreads have two flavors: floating-stack mode, which allows variable 635 // stack size; and fixed-stack mode. NPTL is always floating-stack. 636 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 637 os::Linux::set_is_floating_stack(); 638 } 639 } 640 641 ///////////////////////////////////////////////////////////////////////////// 642 // thread stack 643 644 // Force Linux kernel to expand current thread stack. If "bottom" is close 645 // to the stack guard, caller should block all signals. 646 // 647 // MAP_GROWSDOWN: 648 // A special mmap() flag that is used to implement thread stacks. It tells 649 // kernel that the memory region should extend downwards when needed. This 650 // allows early versions of LinuxThreads to only mmap the first few pages 651 // when creating a new thread. Linux kernel will automatically expand thread 652 // stack as needed (on page faults). 653 // 654 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 655 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 656 // region, it's hard to tell if the fault is due to a legitimate stack 657 // access or because of reading/writing non-exist memory (e.g. buffer 658 // overrun). As a rule, if the fault happens below current stack pointer, 659 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 660 // application (see Linux kernel fault.c). 661 // 662 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 663 // stack overflow detection. 664 // 665 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 666 // not use this flag. However, the stack of initial thread is not created 667 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 668 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 669 // and then attach the thread to JVM. 670 // 671 // To get around the problem and allow stack banging on Linux, we need to 672 // manually expand thread stack after receiving the SIGSEGV. 673 // 674 // There are two ways to expand thread stack to address "bottom", we used 675 // both of them in JVM before 1.5: 676 // 1. adjust stack pointer first so that it is below "bottom", and then 677 // touch "bottom" 678 // 2. mmap() the page in question 679 // 680 // Now alternate signal stack is gone, it's harder to use 2. For instance, 681 // if current sp is already near the lower end of page 101, and we need to 682 // call mmap() to map page 100, it is possible that part of the mmap() frame 683 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 684 // That will destroy the mmap() frame and cause VM to crash. 685 // 686 // The following code works by adjusting sp first, then accessing the "bottom" 687 // page to force a page fault. Linux kernel will then automatically expand the 688 // stack mapping. 689 // 690 // _expand_stack_to() assumes its frame size is less than page size, which 691 // should always be true if the function is not inlined. 692 693 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 694 #define NOINLINE 695 #else 696 #define NOINLINE __attribute__ ((noinline)) 697 #endif 698 699 static void _expand_stack_to(address bottom) NOINLINE; 700 701 static void _expand_stack_to(address bottom) { 702 address sp; 703 size_t size; 704 volatile char *p; 705 706 // Adjust bottom to point to the largest address within the same page, it 707 // gives us a one-page buffer if alloca() allocates slightly more memory. 708 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 709 bottom += os::Linux::page_size() - 1; 710 711 // sp might be slightly above current stack pointer; if that's the case, we 712 // will alloca() a little more space than necessary, which is OK. Don't use 713 // os::current_stack_pointer(), as its result can be slightly below current 714 // stack pointer, causing us to not alloca enough to reach "bottom". 715 sp = (address)&sp; 716 717 if (sp > bottom) { 718 size = sp - bottom; 719 p = (volatile char *)alloca(size); 720 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 721 p[0] = '\0'; 722 } 723 } 724 725 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 726 assert(t!=NULL, "just checking"); 727 assert(t->osthread()->expanding_stack(), "expand should be set"); 728 assert(t->stack_base() != NULL, "stack_base was not initialized"); 729 730 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 731 sigset_t mask_all, old_sigset; 732 sigfillset(&mask_all); 733 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 734 _expand_stack_to(addr); 735 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 736 return true; 737 } 738 return false; 739 } 740 741 ////////////////////////////////////////////////////////////////////////////// 742 // create new thread 743 744 static address highest_vm_reserved_address(); 745 746 // check if it's safe to start a new thread 747 static bool _thread_safety_check(Thread* thread) { 748 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 749 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 750 // Heap is mmap'ed at lower end of memory space. Thread stacks are 751 // allocated (MAP_FIXED) from high address space. Every thread stack 752 // occupies a fixed size slot (usually 2Mbytes, but user can change 753 // it to other values if they rebuild LinuxThreads). 754 // 755 // Problem with MAP_FIXED is that mmap() can still succeed even part of 756 // the memory region has already been mmap'ed. That means if we have too 757 // many threads and/or very large heap, eventually thread stack will 758 // collide with heap. 759 // 760 // Here we try to prevent heap/stack collision by comparing current 761 // stack bottom with the highest address that has been mmap'ed by JVM 762 // plus a safety margin for memory maps created by native code. 763 // 764 // This feature can be disabled by setting ThreadSafetyMargin to 0 765 // 766 if (ThreadSafetyMargin > 0) { 767 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 768 769 // not safe if our stack extends below the safety margin 770 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 771 } else { 772 return true; 773 } 774 } else { 775 // Floating stack LinuxThreads or NPTL: 776 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 777 // there's not enough space left, pthread_create() will fail. If we come 778 // here, that means enough space has been reserved for stack. 779 return true; 780 } 781 } 782 783 // Thread start routine for all newly created threads 784 static void *java_start(Thread *thread) { 785 // Try to randomize the cache line index of hot stack frames. 786 // This helps when threads of the same stack traces evict each other's 787 // cache lines. The threads can be either from the same JVM instance, or 788 // from different JVM instances. The benefit is especially true for 789 // processors with hyperthreading technology. 790 static int counter = 0; 791 int pid = os::current_process_id(); 792 alloca(((pid ^ counter++) & 7) * 128); 793 794 ThreadLocalStorage::set_thread(thread); 795 796 OSThread* osthread = thread->osthread(); 797 Monitor* sync = osthread->startThread_lock(); 798 799 // non floating stack LinuxThreads needs extra check, see above 800 if (!_thread_safety_check(thread)) { 801 // notify parent thread 802 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 803 osthread->set_state(ZOMBIE); 804 sync->notify_all(); 805 return NULL; 806 } 807 808 // thread_id is kernel thread id (similar to Solaris LWP id) 809 osthread->set_thread_id(os::Linux::gettid()); 810 811 if (UseNUMA) { 812 int lgrp_id = os::numa_get_group_id(); 813 if (lgrp_id != -1) { 814 thread->set_lgrp_id(lgrp_id); 815 } 816 } 817 // initialize signal mask for this thread 818 os::Linux::hotspot_sigmask(thread); 819 820 // initialize floating point control register 821 os::Linux::init_thread_fpu_state(); 822 823 // handshaking with parent thread 824 { 825 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 826 827 // notify parent thread 828 osthread->set_state(INITIALIZED); 829 sync->notify_all(); 830 831 // wait until os::start_thread() 832 while (osthread->get_state() == INITIALIZED) { 833 sync->wait(Mutex::_no_safepoint_check_flag); 834 } 835 } 836 837 // call one more level start routine 838 thread->run(); 839 840 return 0; 841 } 842 843 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 844 assert(thread->osthread() == NULL, "caller responsible"); 845 846 // Allocate the OSThread object 847 OSThread* osthread = new OSThread(NULL, NULL); 848 if (osthread == NULL) { 849 return false; 850 } 851 852 // set the correct thread state 853 osthread->set_thread_type(thr_type); 854 855 // Initial state is ALLOCATED but not INITIALIZED 856 osthread->set_state(ALLOCATED); 857 858 thread->set_osthread(osthread); 859 860 // init thread attributes 861 pthread_attr_t attr; 862 pthread_attr_init(&attr); 863 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 864 865 // stack size 866 if (os::Linux::supports_variable_stack_size()) { 867 // calculate stack size if it's not specified by caller 868 if (stack_size == 0) { 869 stack_size = os::Linux::default_stack_size(thr_type); 870 871 switch (thr_type) { 872 case os::java_thread: 873 // Java threads use ThreadStackSize which default value can be 874 // changed with the flag -Xss 875 assert (JavaThread::stack_size_at_create() > 0, "this should be set"); 876 stack_size = JavaThread::stack_size_at_create(); 877 break; 878 case os::compiler_thread: 879 if (CompilerThreadStackSize > 0) { 880 stack_size = (size_t)(CompilerThreadStackSize * K); 881 break; 882 } // else fall through: 883 // use VMThreadStackSize if CompilerThreadStackSize is not defined 884 case os::vm_thread: 885 case os::pgc_thread: 886 case os::cgc_thread: 887 case os::watcher_thread: 888 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 889 break; 890 } 891 } 892 893 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 894 pthread_attr_setstacksize(&attr, stack_size); 895 } else { 896 // let pthread_create() pick the default value. 897 } 898 899 // glibc guard page 900 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 901 902 ThreadState state; 903 904 { 905 // Serialize thread creation if we are running with fixed stack LinuxThreads 906 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 907 if (lock) { 908 os::Linux::createThread_lock()->lock_without_safepoint_check(); 909 } 910 911 pthread_t tid; 912 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 913 914 pthread_attr_destroy(&attr); 915 916 if (ret != 0) { 917 if (PrintMiscellaneous && (Verbose || WizardMode)) { 918 perror("pthread_create()"); 919 } 920 // Need to clean up stuff we've allocated so far 921 thread->set_osthread(NULL); 922 delete osthread; 923 if (lock) os::Linux::createThread_lock()->unlock(); 924 return false; 925 } 926 927 // Store pthread info into the OSThread 928 osthread->set_pthread_id(tid); 929 930 // Wait until child thread is either initialized or aborted 931 { 932 Monitor* sync_with_child = osthread->startThread_lock(); 933 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 934 while ((state = osthread->get_state()) == ALLOCATED) { 935 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 936 } 937 } 938 939 if (lock) { 940 os::Linux::createThread_lock()->unlock(); 941 } 942 } 943 944 // Aborted due to thread limit being reached 945 if (state == ZOMBIE) { 946 thread->set_osthread(NULL); 947 delete osthread; 948 return false; 949 } 950 951 // The thread is returned suspended (in state INITIALIZED), 952 // and is started higher up in the call chain 953 assert(state == INITIALIZED, "race condition"); 954 return true; 955 } 956 957 ///////////////////////////////////////////////////////////////////////////// 958 // attach existing thread 959 960 // bootstrap the main thread 961 bool os::create_main_thread(JavaThread* thread) { 962 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 963 return create_attached_thread(thread); 964 } 965 966 bool os::create_attached_thread(JavaThread* thread) { 967 #ifdef ASSERT 968 thread->verify_not_published(); 969 #endif 970 971 // Allocate the OSThread object 972 OSThread* osthread = new OSThread(NULL, NULL); 973 974 if (osthread == NULL) { 975 return false; 976 } 977 978 // Store pthread info into the OSThread 979 osthread->set_thread_id(os::Linux::gettid()); 980 osthread->set_pthread_id(::pthread_self()); 981 982 // initialize floating point control register 983 os::Linux::init_thread_fpu_state(); 984 985 // Initial thread state is RUNNABLE 986 osthread->set_state(RUNNABLE); 987 988 thread->set_osthread(osthread); 989 990 if (UseNUMA) { 991 int lgrp_id = os::numa_get_group_id(); 992 if (lgrp_id != -1) { 993 thread->set_lgrp_id(lgrp_id); 994 } 995 } 996 997 if (os::Linux::is_initial_thread()) { 998 // If current thread is initial thread, its stack is mapped on demand, 999 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 1000 // the entire stack region to avoid SEGV in stack banging. 1001 // It is also useful to get around the heap-stack-gap problem on SuSE 1002 // kernel (see 4821821 for details). We first expand stack to the top 1003 // of yellow zone, then enable stack yellow zone (order is significant, 1004 // enabling yellow zone first will crash JVM on SuSE Linux), so there 1005 // is no gap between the last two virtual memory regions. 1006 1007 JavaThread *jt = (JavaThread *)thread; 1008 address addr = jt->stack_yellow_zone_base(); 1009 assert(addr != NULL, "initialization problem?"); 1010 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 1011 1012 osthread->set_expanding_stack(); 1013 os::Linux::manually_expand_stack(jt, addr); 1014 osthread->clear_expanding_stack(); 1015 } 1016 1017 // initialize signal mask for this thread 1018 // and save the caller's signal mask 1019 os::Linux::hotspot_sigmask(thread); 1020 1021 return true; 1022 } 1023 1024 void os::pd_start_thread(Thread* thread) { 1025 OSThread * osthread = thread->osthread(); 1026 assert(osthread->get_state() != INITIALIZED, "just checking"); 1027 Monitor* sync_with_child = osthread->startThread_lock(); 1028 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 1029 sync_with_child->notify(); 1030 } 1031 1032 // Free Linux resources related to the OSThread 1033 void os::free_thread(OSThread* osthread) { 1034 assert(osthread != NULL, "osthread not set"); 1035 1036 if (Thread::current()->osthread() == osthread) { 1037 // Restore caller's signal mask 1038 sigset_t sigmask = osthread->caller_sigmask(); 1039 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1040 } 1041 1042 delete osthread; 1043 } 1044 1045 ////////////////////////////////////////////////////////////////////////////// 1046 // thread local storage 1047 1048 int os::allocate_thread_local_storage() { 1049 pthread_key_t key; 1050 int rslt = pthread_key_create(&key, NULL); 1051 assert(rslt == 0, "cannot allocate thread local storage"); 1052 return (int)key; 1053 } 1054 1055 // Note: This is currently not used by VM, as we don't destroy TLS key 1056 // on VM exit. 1057 void os::free_thread_local_storage(int index) { 1058 int rslt = pthread_key_delete((pthread_key_t)index); 1059 assert(rslt == 0, "invalid index"); 1060 } 1061 1062 void os::thread_local_storage_at_put(int index, void* value) { 1063 int rslt = pthread_setspecific((pthread_key_t)index, value); 1064 assert(rslt == 0, "pthread_setspecific failed"); 1065 } 1066 1067 extern "C" Thread* get_thread() { 1068 return ThreadLocalStorage::thread(); 1069 } 1070 1071 ////////////////////////////////////////////////////////////////////////////// 1072 // initial thread 1073 1074 // Check if current thread is the initial thread, similar to Solaris thr_main. 1075 bool os::Linux::is_initial_thread(void) { 1076 char dummy; 1077 // If called before init complete, thread stack bottom will be null. 1078 // Can be called if fatal error occurs before initialization. 1079 if (initial_thread_stack_bottom() == NULL) return false; 1080 assert(initial_thread_stack_bottom() != NULL && 1081 initial_thread_stack_size() != 0, 1082 "os::init did not locate initial thread's stack region"); 1083 if ((address)&dummy >= initial_thread_stack_bottom() && 1084 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1085 return true; 1086 else return false; 1087 } 1088 1089 // Find the virtual memory area that contains addr 1090 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1091 FILE *fp = fopen("/proc/self/maps", "r"); 1092 if (fp) { 1093 address low, high; 1094 while (!feof(fp)) { 1095 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1096 if (low <= addr && addr < high) { 1097 if (vma_low) *vma_low = low; 1098 if (vma_high) *vma_high = high; 1099 fclose (fp); 1100 return true; 1101 } 1102 } 1103 for (;;) { 1104 int ch = fgetc(fp); 1105 if (ch == EOF || ch == (int)'\n') break; 1106 } 1107 } 1108 fclose(fp); 1109 } 1110 return false; 1111 } 1112 1113 // Locate initial thread stack. This special handling of initial thread stack 1114 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1115 // bogus value for initial thread. 1116 void os::Linux::capture_initial_stack(size_t max_size) { 1117 // stack size is the easy part, get it from RLIMIT_STACK 1118 size_t stack_size; 1119 struct rlimit rlim; 1120 getrlimit(RLIMIT_STACK, &rlim); 1121 stack_size = rlim.rlim_cur; 1122 1123 // 6308388: a bug in ld.so will relocate its own .data section to the 1124 // lower end of primordial stack; reduce ulimit -s value a little bit 1125 // so we won't install guard page on ld.so's data section. 1126 stack_size -= 2 * page_size(); 1127 1128 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1129 // 7.1, in both cases we will get 2G in return value. 1130 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1131 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1132 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1133 // in case other parts in glibc still assumes 2M max stack size. 1134 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1135 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1136 if (stack_size > 2 * K * K IA64_ONLY(*2)) 1137 stack_size = 2 * K * K IA64_ONLY(*2); 1138 // Try to figure out where the stack base (top) is. This is harder. 1139 // 1140 // When an application is started, glibc saves the initial stack pointer in 1141 // a global variable "__libc_stack_end", which is then used by system 1142 // libraries. __libc_stack_end should be pretty close to stack top. The 1143 // variable is available since the very early days. However, because it is 1144 // a private interface, it could disappear in the future. 1145 // 1146 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1147 // to __libc_stack_end, it is very close to stack top, but isn't the real 1148 // stack top. Note that /proc may not exist if VM is running as a chroot 1149 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1150 // /proc/<pid>/stat could change in the future (though unlikely). 1151 // 1152 // We try __libc_stack_end first. If that doesn't work, look for 1153 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1154 // as a hint, which should work well in most cases. 1155 1156 uintptr_t stack_start; 1157 1158 // try __libc_stack_end first 1159 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1160 if (p && *p) { 1161 stack_start = *p; 1162 } else { 1163 // see if we can get the start_stack field from /proc/self/stat 1164 FILE *fp; 1165 int pid; 1166 char state; 1167 int ppid; 1168 int pgrp; 1169 int session; 1170 int nr; 1171 int tpgrp; 1172 unsigned long flags; 1173 unsigned long minflt; 1174 unsigned long cminflt; 1175 unsigned long majflt; 1176 unsigned long cmajflt; 1177 unsigned long utime; 1178 unsigned long stime; 1179 long cutime; 1180 long cstime; 1181 long prio; 1182 long nice; 1183 long junk; 1184 long it_real; 1185 uintptr_t start; 1186 uintptr_t vsize; 1187 intptr_t rss; 1188 uintptr_t rsslim; 1189 uintptr_t scodes; 1190 uintptr_t ecode; 1191 int i; 1192 1193 // Figure what the primordial thread stack base is. Code is inspired 1194 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1195 // followed by command name surrounded by parentheses, state, etc. 1196 char stat[2048]; 1197 int statlen; 1198 1199 fp = fopen("/proc/self/stat", "r"); 1200 if (fp) { 1201 statlen = fread(stat, 1, 2047, fp); 1202 stat[statlen] = '\0'; 1203 fclose(fp); 1204 1205 // Skip pid and the command string. Note that we could be dealing with 1206 // weird command names, e.g. user could decide to rename java launcher 1207 // to "java 1.4.2 :)", then the stat file would look like 1208 // 1234 (java 1.4.2 :)) R ... ... 1209 // We don't really need to know the command string, just find the last 1210 // occurrence of ")" and then start parsing from there. See bug 4726580. 1211 char * s = strrchr(stat, ')'); 1212 1213 i = 0; 1214 if (s) { 1215 // Skip blank chars 1216 do s++; while (isspace(*s)); 1217 1218 #define _UFM UINTX_FORMAT 1219 #define _DFM INTX_FORMAT 1220 1221 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1222 /* 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 */ 1223 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, 1224 &state, /* 3 %c */ 1225 &ppid, /* 4 %d */ 1226 &pgrp, /* 5 %d */ 1227 &session, /* 6 %d */ 1228 &nr, /* 7 %d */ 1229 &tpgrp, /* 8 %d */ 1230 &flags, /* 9 %lu */ 1231 &minflt, /* 10 %lu */ 1232 &cminflt, /* 11 %lu */ 1233 &majflt, /* 12 %lu */ 1234 &cmajflt, /* 13 %lu */ 1235 &utime, /* 14 %lu */ 1236 &stime, /* 15 %lu */ 1237 &cutime, /* 16 %ld */ 1238 &cstime, /* 17 %ld */ 1239 &prio, /* 18 %ld */ 1240 &nice, /* 19 %ld */ 1241 &junk, /* 20 %ld */ 1242 &it_real, /* 21 %ld */ 1243 &start, /* 22 UINTX_FORMAT */ 1244 &vsize, /* 23 UINTX_FORMAT */ 1245 &rss, /* 24 INTX_FORMAT */ 1246 &rsslim, /* 25 UINTX_FORMAT */ 1247 &scodes, /* 26 UINTX_FORMAT */ 1248 &ecode, /* 27 UINTX_FORMAT */ 1249 &stack_start); /* 28 UINTX_FORMAT */ 1250 } 1251 1252 #undef _UFM 1253 #undef _DFM 1254 1255 if (i != 28 - 2) { 1256 assert(false, "Bad conversion from /proc/self/stat"); 1257 // product mode - assume we are the initial thread, good luck in the 1258 // embedded case. 1259 warning("Can't detect initial thread stack location - bad conversion"); 1260 stack_start = (uintptr_t) &rlim; 1261 } 1262 } else { 1263 // For some reason we can't open /proc/self/stat (for example, running on 1264 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1265 // most cases, so don't abort: 1266 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1267 stack_start = (uintptr_t) &rlim; 1268 } 1269 } 1270 1271 // Now we have a pointer (stack_start) very close to the stack top, the 1272 // next thing to do is to figure out the exact location of stack top. We 1273 // can find out the virtual memory area that contains stack_start by 1274 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1275 // and its upper limit is the real stack top. (again, this would fail if 1276 // running inside chroot, because /proc may not exist.) 1277 1278 uintptr_t stack_top; 1279 address low, high; 1280 if (find_vma((address)stack_start, &low, &high)) { 1281 // success, "high" is the true stack top. (ignore "low", because initial 1282 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1283 stack_top = (uintptr_t)high; 1284 } else { 1285 // failed, likely because /proc/self/maps does not exist 1286 warning("Can't detect initial thread stack location - find_vma failed"); 1287 // best effort: stack_start is normally within a few pages below the real 1288 // stack top, use it as stack top, and reduce stack size so we won't put 1289 // guard page outside stack. 1290 stack_top = stack_start; 1291 stack_size -= 16 * page_size(); 1292 } 1293 1294 // stack_top could be partially down the page so align it 1295 stack_top = align_size_up(stack_top, page_size()); 1296 1297 if (max_size && stack_size > max_size) { 1298 _initial_thread_stack_size = max_size; 1299 } else { 1300 _initial_thread_stack_size = stack_size; 1301 } 1302 1303 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1304 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1305 } 1306 1307 //////////////////////////////////////////////////////////////////////////////// 1308 // time support 1309 1310 // Time since start-up in seconds to a fine granularity. 1311 // Used by VMSelfDestructTimer and the MemProfiler. 1312 double os::elapsedTime() { 1313 1314 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution 1315 } 1316 1317 jlong os::elapsed_counter() { 1318 return javaTimeNanos() - initial_time_count; 1319 } 1320 1321 jlong os::elapsed_frequency() { 1322 return NANOSECS_PER_SEC; // nanosecond resolution 1323 } 1324 1325 bool os::supports_vtime() { return true; } 1326 bool os::enable_vtime() { return false; } 1327 bool os::vtime_enabled() { return false; } 1328 1329 double os::elapsedVTime() { 1330 struct rusage usage; 1331 int retval = getrusage(RUSAGE_THREAD, &usage); 1332 if (retval == 0) { 1333 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); 1334 } else { 1335 // better than nothing, but not much 1336 return elapsedTime(); 1337 } 1338 } 1339 1340 jlong os::javaTimeMillis() { 1341 timeval time; 1342 int status = gettimeofday(&time, NULL); 1343 assert(status != -1, "linux error"); 1344 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1345 } 1346 1347 #ifndef CLOCK_MONOTONIC 1348 #define CLOCK_MONOTONIC (1) 1349 #endif 1350 1351 void os::Linux::clock_init() { 1352 // we do dlopen's in this particular order due to bug in linux 1353 // dynamical loader (see 6348968) leading to crash on exit 1354 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1355 if (handle == NULL) { 1356 handle = dlopen("librt.so", RTLD_LAZY); 1357 } 1358 1359 if (handle) { 1360 int (*clock_getres_func)(clockid_t, struct timespec*) = 1361 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1362 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1363 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1364 if (clock_getres_func && clock_gettime_func) { 1365 // See if monotonic clock is supported by the kernel. Note that some 1366 // early implementations simply return kernel jiffies (updated every 1367 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1368 // for nano time (though the monotonic property is still nice to have). 1369 // It's fixed in newer kernels, however clock_getres() still returns 1370 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1371 // resolution for now. Hopefully as people move to new kernels, this 1372 // won't be a problem. 1373 struct timespec res; 1374 struct timespec tp; 1375 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1376 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1377 // yes, monotonic clock is supported 1378 _clock_gettime = clock_gettime_func; 1379 return; 1380 } else { 1381 // close librt if there is no monotonic clock 1382 dlclose(handle); 1383 } 1384 } 1385 } 1386 warning("No monotonic clock was available - timed services may " \ 1387 "be adversely affected if the time-of-day clock changes"); 1388 } 1389 1390 #ifndef SYS_clock_getres 1391 1392 #if defined(IA32) || defined(AMD64) 1393 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1394 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1395 #else 1396 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1397 #define sys_clock_getres(x,y) -1 1398 #endif 1399 1400 #else 1401 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1402 #endif 1403 1404 void os::Linux::fast_thread_clock_init() { 1405 if (!UseLinuxPosixThreadCPUClocks) { 1406 return; 1407 } 1408 clockid_t clockid; 1409 struct timespec tp; 1410 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1411 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1412 1413 // Switch to using fast clocks for thread cpu time if 1414 // the sys_clock_getres() returns 0 error code. 1415 // Note, that some kernels may support the current thread 1416 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1417 // returned by the pthread_getcpuclockid(). 1418 // If the fast Posix clocks are supported then the sys_clock_getres() 1419 // must return at least tp.tv_sec == 0 which means a resolution 1420 // better than 1 sec. This is extra check for reliability. 1421 1422 if(pthread_getcpuclockid_func && 1423 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1424 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1425 1426 _supports_fast_thread_cpu_time = true; 1427 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1428 } 1429 } 1430 1431 jlong os::javaTimeNanos() { 1432 if (os::supports_monotonic_clock()) { 1433 struct timespec tp; 1434 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1435 assert(status == 0, "gettime error"); 1436 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1437 return result; 1438 } else { 1439 timeval time; 1440 int status = gettimeofday(&time, NULL); 1441 assert(status != -1, "linux error"); 1442 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1443 return 1000 * usecs; 1444 } 1445 } 1446 1447 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1448 if (os::supports_monotonic_clock()) { 1449 info_ptr->max_value = ALL_64_BITS; 1450 1451 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1452 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1453 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1454 } else { 1455 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1456 info_ptr->max_value = ALL_64_BITS; 1457 1458 // gettimeofday is a real time clock so it skips 1459 info_ptr->may_skip_backward = true; 1460 info_ptr->may_skip_forward = true; 1461 } 1462 1463 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1464 } 1465 1466 // Return the real, user, and system times in seconds from an 1467 // arbitrary fixed point in the past. 1468 bool os::getTimesSecs(double* process_real_time, 1469 double* process_user_time, 1470 double* process_system_time) { 1471 struct tms ticks; 1472 clock_t real_ticks = times(&ticks); 1473 1474 if (real_ticks == (clock_t) (-1)) { 1475 return false; 1476 } else { 1477 double ticks_per_second = (double) clock_tics_per_sec; 1478 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1479 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1480 *process_real_time = ((double) real_ticks) / ticks_per_second; 1481 1482 return true; 1483 } 1484 } 1485 1486 1487 char * os::local_time_string(char *buf, size_t buflen) { 1488 struct tm t; 1489 time_t long_time; 1490 time(&long_time); 1491 localtime_r(&long_time, &t); 1492 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1493 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1494 t.tm_hour, t.tm_min, t.tm_sec); 1495 return buf; 1496 } 1497 1498 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1499 return localtime_r(clock, res); 1500 } 1501 1502 //////////////////////////////////////////////////////////////////////////////// 1503 // runtime exit support 1504 1505 // Note: os::shutdown() might be called very early during initialization, or 1506 // called from signal handler. Before adding something to os::shutdown(), make 1507 // sure it is async-safe and can handle partially initialized VM. 1508 void os::shutdown() { 1509 1510 // allow PerfMemory to attempt cleanup of any persistent resources 1511 perfMemory_exit(); 1512 1513 // needs to remove object in file system 1514 AttachListener::abort(); 1515 1516 // flush buffered output, finish log files 1517 ostream_abort(); 1518 1519 // Check for abort hook 1520 abort_hook_t abort_hook = Arguments::abort_hook(); 1521 if (abort_hook != NULL) { 1522 abort_hook(); 1523 } 1524 1525 } 1526 1527 // Note: os::abort() might be called very early during initialization, or 1528 // called from signal handler. Before adding something to os::abort(), make 1529 // sure it is async-safe and can handle partially initialized VM. 1530 void os::abort(bool dump_core) { 1531 os::shutdown(); 1532 if (dump_core) { 1533 #ifndef PRODUCT 1534 fdStream out(defaultStream::output_fd()); 1535 out.print_raw("Current thread is "); 1536 char buf[16]; 1537 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1538 out.print_raw_cr(buf); 1539 out.print_raw_cr("Dumping core ..."); 1540 #endif 1541 ::abort(); // dump core 1542 } 1543 1544 ::exit(1); 1545 } 1546 1547 // Die immediately, no exit hook, no abort hook, no cleanup. 1548 void os::die() { 1549 // _exit() on LinuxThreads only kills current thread 1550 ::abort(); 1551 } 1552 1553 // unused on linux for now. 1554 void os::set_error_file(const char *logfile) {} 1555 1556 1557 // This method is a copy of JDK's sysGetLastErrorString 1558 // from src/solaris/hpi/src/system_md.c 1559 1560 size_t os::lasterror(char *buf, size_t len) { 1561 1562 if (errno == 0) return 0; 1563 1564 const char *s = ::strerror(errno); 1565 size_t n = ::strlen(s); 1566 if (n >= len) { 1567 n = len - 1; 1568 } 1569 ::strncpy(buf, s, n); 1570 buf[n] = '\0'; 1571 return n; 1572 } 1573 1574 intx os::current_thread_id() { return (intx)pthread_self(); } 1575 int os::current_process_id() { 1576 1577 // Under the old linux thread library, linux gives each thread 1578 // its own process id. Because of this each thread will return 1579 // a different pid if this method were to return the result 1580 // of getpid(2). Linux provides no api that returns the pid 1581 // of the launcher thread for the vm. This implementation 1582 // returns a unique pid, the pid of the launcher thread 1583 // that starts the vm 'process'. 1584 1585 // Under the NPTL, getpid() returns the same pid as the 1586 // launcher thread rather than a unique pid per thread. 1587 // Use gettid() if you want the old pre NPTL behaviour. 1588 1589 // if you are looking for the result of a call to getpid() that 1590 // returns a unique pid for the calling thread, then look at the 1591 // OSThread::thread_id() method in osThread_linux.hpp file 1592 1593 return (int)(_initial_pid ? _initial_pid : getpid()); 1594 } 1595 1596 // DLL functions 1597 1598 const char* os::dll_file_extension() { return ".so"; } 1599 1600 // This must be hard coded because it's the system's temporary 1601 // directory not the java application's temp directory, ala java.io.tmpdir. 1602 const char* os::get_temp_directory() { return "/tmp"; } 1603 1604 static bool file_exists(const char* filename) { 1605 struct stat statbuf; 1606 if (filename == NULL || strlen(filename) == 0) { 1607 return false; 1608 } 1609 return os::stat(filename, &statbuf) == 0; 1610 } 1611 1612 bool os::dll_build_name(char* buffer, size_t buflen, 1613 const char* pname, const char* fname) { 1614 bool retval = false; 1615 // Copied from libhpi 1616 const size_t pnamelen = pname ? strlen(pname) : 0; 1617 1618 // Return error on buffer overflow. 1619 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1620 return retval; 1621 } 1622 1623 if (pnamelen == 0) { 1624 snprintf(buffer, buflen, "lib%s.so", fname); 1625 retval = true; 1626 } else if (strchr(pname, *os::path_separator()) != NULL) { 1627 int n; 1628 char** pelements = split_path(pname, &n); 1629 if (pelements == NULL) { 1630 return false; 1631 } 1632 for (int i = 0 ; i < n ; i++) { 1633 // Really shouldn't be NULL, but check can't hurt 1634 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1635 continue; // skip the empty path values 1636 } 1637 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1638 if (file_exists(buffer)) { 1639 retval = true; 1640 break; 1641 } 1642 } 1643 // release the storage 1644 for (int i = 0 ; i < n ; i++) { 1645 if (pelements[i] != NULL) { 1646 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal); 1647 } 1648 } 1649 if (pelements != NULL) { 1650 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal); 1651 } 1652 } else { 1653 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1654 retval = true; 1655 } 1656 return retval; 1657 } 1658 1659 // check if addr is inside libjvm.so 1660 bool os::address_is_in_vm(address addr) { 1661 static address libjvm_base_addr; 1662 Dl_info dlinfo; 1663 1664 if (libjvm_base_addr == NULL) { 1665 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1666 libjvm_base_addr = (address)dlinfo.dli_fbase; 1667 } 1668 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1669 } 1670 1671 if (dladdr((void *)addr, &dlinfo) != 0) { 1672 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1673 } 1674 1675 return false; 1676 } 1677 1678 bool os::dll_address_to_function_name(address addr, char *buf, 1679 int buflen, int *offset) { 1680 // buf is not optional, but offset is optional 1681 assert(buf != NULL, "sanity check"); 1682 1683 Dl_info dlinfo; 1684 1685 if (dladdr((void*)addr, &dlinfo) != 0) { 1686 // see if we have a matching symbol 1687 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1688 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1689 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1690 } 1691 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1692 return true; 1693 } 1694 // no matching symbol so try for just file info 1695 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1696 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1697 buf, buflen, offset, dlinfo.dli_fname)) { 1698 return true; 1699 } 1700 } 1701 } 1702 1703 buf[0] = '\0'; 1704 if (offset != NULL) *offset = -1; 1705 return false; 1706 } 1707 1708 struct _address_to_library_name { 1709 address addr; // input : memory address 1710 size_t buflen; // size of fname 1711 char* fname; // output: library name 1712 address base; // library base addr 1713 }; 1714 1715 static int address_to_library_name_callback(struct dl_phdr_info *info, 1716 size_t size, void *data) { 1717 int i; 1718 bool found = false; 1719 address libbase = NULL; 1720 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1721 1722 // iterate through all loadable segments 1723 for (i = 0; i < info->dlpi_phnum; i++) { 1724 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1725 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1726 // base address of a library is the lowest address of its loaded 1727 // segments. 1728 if (libbase == NULL || libbase > segbase) { 1729 libbase = segbase; 1730 } 1731 // see if 'addr' is within current segment 1732 if (segbase <= d->addr && 1733 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1734 found = true; 1735 } 1736 } 1737 } 1738 1739 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1740 // so dll_address_to_library_name() can fall through to use dladdr() which 1741 // can figure out executable name from argv[0]. 1742 if (found && info->dlpi_name && info->dlpi_name[0]) { 1743 d->base = libbase; 1744 if (d->fname) { 1745 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1746 } 1747 return 1; 1748 } 1749 return 0; 1750 } 1751 1752 bool os::dll_address_to_library_name(address addr, char* buf, 1753 int buflen, int* offset) { 1754 // buf is not optional, but offset is optional 1755 assert(buf != NULL, "sanity check"); 1756 1757 Dl_info dlinfo; 1758 struct _address_to_library_name data; 1759 1760 // There is a bug in old glibc dladdr() implementation that it could resolve 1761 // to wrong library name if the .so file has a base address != NULL. Here 1762 // we iterate through the program headers of all loaded libraries to find 1763 // out which library 'addr' really belongs to. This workaround can be 1764 // removed once the minimum requirement for glibc is moved to 2.3.x. 1765 data.addr = addr; 1766 data.fname = buf; 1767 data.buflen = buflen; 1768 data.base = NULL; 1769 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1770 1771 if (rslt) { 1772 // buf already contains library name 1773 if (offset) *offset = addr - data.base; 1774 return true; 1775 } 1776 if (dladdr((void*)addr, &dlinfo) != 0) { 1777 if (dlinfo.dli_fname != NULL) { 1778 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1779 } 1780 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1781 *offset = addr - (address)dlinfo.dli_fbase; 1782 } 1783 return true; 1784 } 1785 1786 buf[0] = '\0'; 1787 if (offset) *offset = -1; 1788 return false; 1789 } 1790 1791 // Loads .dll/.so and 1792 // in case of error it checks if .dll/.so was built for the 1793 // same architecture as Hotspot is running on 1794 1795 1796 // Remember the stack's state. The Linux dynamic linker will change 1797 // the stack to 'executable' at most once, so we must safepoint only once. 1798 bool os::Linux::_stack_is_executable = false; 1799 1800 // VM operation that loads a library. This is necessary if stack protection 1801 // of the Java stacks can be lost during loading the library. If we 1802 // do not stop the Java threads, they can stack overflow before the stacks 1803 // are protected again. 1804 class VM_LinuxDllLoad: public VM_Operation { 1805 private: 1806 const char *_filename; 1807 char *_ebuf; 1808 int _ebuflen; 1809 void *_lib; 1810 public: 1811 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1812 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1813 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1814 void doit() { 1815 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1816 os::Linux::_stack_is_executable = true; 1817 } 1818 void* loaded_library() { return _lib; } 1819 }; 1820 1821 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1822 { 1823 void * result = NULL; 1824 bool load_attempted = false; 1825 1826 // Check whether the library to load might change execution rights 1827 // of the stack. If they are changed, the protection of the stack 1828 // guard pages will be lost. We need a safepoint to fix this. 1829 // 1830 // See Linux man page execstack(8) for more info. 1831 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1832 ElfFile ef(filename); 1833 if (!ef.specifies_noexecstack()) { 1834 if (!is_init_completed()) { 1835 os::Linux::_stack_is_executable = true; 1836 // This is OK - No Java threads have been created yet, and hence no 1837 // stack guard pages to fix. 1838 // 1839 // This should happen only when you are building JDK7 using a very 1840 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1841 // 1842 // Dynamic loader will make all stacks executable after 1843 // this function returns, and will not do that again. 1844 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1845 } else { 1846 warning("You have loaded library %s which might have disabled stack guard. " 1847 "The VM will try to fix the stack guard now.\n" 1848 "It's highly recommended that you fix the library with " 1849 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1850 filename); 1851 1852 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1853 JavaThread *jt = JavaThread::current(); 1854 if (jt->thread_state() != _thread_in_native) { 1855 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1856 // that requires ExecStack. Cannot enter safe point. Let's give up. 1857 warning("Unable to fix stack guard. Giving up."); 1858 } else { 1859 if (!LoadExecStackDllInVMThread) { 1860 // This is for the case where the DLL has an static 1861 // constructor function that executes JNI code. We cannot 1862 // load such DLLs in the VMThread. 1863 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1864 } 1865 1866 ThreadInVMfromNative tiv(jt); 1867 debug_only(VMNativeEntryWrapper vew;) 1868 1869 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1870 VMThread::execute(&op); 1871 if (LoadExecStackDllInVMThread) { 1872 result = op.loaded_library(); 1873 } 1874 load_attempted = true; 1875 } 1876 } 1877 } 1878 } 1879 1880 if (!load_attempted) { 1881 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1882 } 1883 1884 if (result != NULL) { 1885 // Successful loading 1886 return result; 1887 } 1888 1889 Elf32_Ehdr elf_head; 1890 int diag_msg_max_length=ebuflen-strlen(ebuf); 1891 char* diag_msg_buf=ebuf+strlen(ebuf); 1892 1893 if (diag_msg_max_length==0) { 1894 // No more space in ebuf for additional diagnostics message 1895 return NULL; 1896 } 1897 1898 1899 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1900 1901 if (file_descriptor < 0) { 1902 // Can't open library, report dlerror() message 1903 return NULL; 1904 } 1905 1906 bool failed_to_read_elf_head= 1907 (sizeof(elf_head)!= 1908 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1909 1910 ::close(file_descriptor); 1911 if (failed_to_read_elf_head) { 1912 // file i/o error - report dlerror() msg 1913 return NULL; 1914 } 1915 1916 typedef struct { 1917 Elf32_Half code; // Actual value as defined in elf.h 1918 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1919 char elf_class; // 32 or 64 bit 1920 char endianess; // MSB or LSB 1921 char* name; // String representation 1922 } arch_t; 1923 1924 #ifndef EM_486 1925 #define EM_486 6 /* Intel 80486 */ 1926 #endif 1927 1928 static const arch_t arch_array[]={ 1929 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1930 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1931 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1932 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1933 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1934 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1935 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1936 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1937 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1938 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1939 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1940 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1941 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1942 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1943 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1944 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1945 }; 1946 1947 #if (defined IA32) 1948 static Elf32_Half running_arch_code=EM_386; 1949 #elif (defined AMD64) 1950 static Elf32_Half running_arch_code=EM_X86_64; 1951 #elif (defined IA64) 1952 static Elf32_Half running_arch_code=EM_IA_64; 1953 #elif (defined __sparc) && (defined _LP64) 1954 static Elf32_Half running_arch_code=EM_SPARCV9; 1955 #elif (defined __sparc) && (!defined _LP64) 1956 static Elf32_Half running_arch_code=EM_SPARC; 1957 #elif (defined __powerpc64__) 1958 static Elf32_Half running_arch_code=EM_PPC64; 1959 #elif (defined __powerpc__) 1960 static Elf32_Half running_arch_code=EM_PPC; 1961 #elif (defined ARM) 1962 static Elf32_Half running_arch_code=EM_ARM; 1963 #elif (defined S390) 1964 static Elf32_Half running_arch_code=EM_S390; 1965 #elif (defined ALPHA) 1966 static Elf32_Half running_arch_code=EM_ALPHA; 1967 #elif (defined MIPSEL) 1968 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1969 #elif (defined PARISC) 1970 static Elf32_Half running_arch_code=EM_PARISC; 1971 #elif (defined MIPS) 1972 static Elf32_Half running_arch_code=EM_MIPS; 1973 #elif (defined M68K) 1974 static Elf32_Half running_arch_code=EM_68K; 1975 #else 1976 #error Method os::dll_load requires that one of following is defined:\ 1977 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1978 #endif 1979 1980 // Identify compatability class for VM's architecture and library's architecture 1981 // Obtain string descriptions for architectures 1982 1983 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1984 int running_arch_index=-1; 1985 1986 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 1987 if (running_arch_code == arch_array[i].code) { 1988 running_arch_index = i; 1989 } 1990 if (lib_arch.code == arch_array[i].code) { 1991 lib_arch.compat_class = arch_array[i].compat_class; 1992 lib_arch.name = arch_array[i].name; 1993 } 1994 } 1995 1996 assert(running_arch_index != -1, 1997 "Didn't find running architecture code (running_arch_code) in arch_array"); 1998 if (running_arch_index == -1) { 1999 // Even though running architecture detection failed 2000 // we may still continue with reporting dlerror() message 2001 return NULL; 2002 } 2003 2004 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 2005 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 2006 return NULL; 2007 } 2008 2009 #ifndef S390 2010 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 2011 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 2012 return NULL; 2013 } 2014 #endif // !S390 2015 2016 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 2017 if ( lib_arch.name!=NULL ) { 2018 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2019 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 2020 lib_arch.name, arch_array[running_arch_index].name); 2021 } else { 2022 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2023 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 2024 lib_arch.code, 2025 arch_array[running_arch_index].name); 2026 } 2027 } 2028 2029 return NULL; 2030 } 2031 2032 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) { 2033 void * result = ::dlopen(filename, RTLD_LAZY); 2034 if (result == NULL) { 2035 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2036 ebuf[ebuflen-1] = '\0'; 2037 } 2038 return result; 2039 } 2040 2041 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) { 2042 void * result = NULL; 2043 if (LoadExecStackDllInVMThread) { 2044 result = dlopen_helper(filename, ebuf, ebuflen); 2045 } 2046 2047 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2048 // library that requires an executable stack, or which does not have this 2049 // stack attribute set, dlopen changes the stack attribute to executable. The 2050 // read protection of the guard pages gets lost. 2051 // 2052 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2053 // may have been queued at the same time. 2054 2055 if (!_stack_is_executable) { 2056 JavaThread *jt = Threads::first(); 2057 2058 while (jt) { 2059 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2060 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2061 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2062 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2063 warning("Attempt to reguard stack yellow zone failed."); 2064 } 2065 } 2066 jt = jt->next(); 2067 } 2068 } 2069 2070 return result; 2071 } 2072 2073 /* 2074 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2075 * chances are you might want to run the generated bits against glibc-2.0 2076 * libdl.so, so always use locking for any version of glibc. 2077 */ 2078 void* os::dll_lookup(void* handle, const char* name) { 2079 pthread_mutex_lock(&dl_mutex); 2080 void* res = dlsym(handle, name); 2081 pthread_mutex_unlock(&dl_mutex); 2082 return res; 2083 } 2084 2085 void* os::get_default_process_handle() { 2086 return (void*)::dlopen(NULL, RTLD_LAZY); 2087 } 2088 2089 static bool _print_ascii_file(const char* filename, outputStream* st) { 2090 int fd = ::open(filename, O_RDONLY); 2091 if (fd == -1) { 2092 return false; 2093 } 2094 2095 char buf[32]; 2096 int bytes; 2097 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2098 st->print_raw(buf, bytes); 2099 } 2100 2101 ::close(fd); 2102 2103 return true; 2104 } 2105 2106 void os::print_dll_info(outputStream *st) { 2107 st->print_cr("Dynamic libraries:"); 2108 2109 char fname[32]; 2110 pid_t pid = os::Linux::gettid(); 2111 2112 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2113 2114 if (!_print_ascii_file(fname, st)) { 2115 st->print("Can not get library information for pid = %d\n", pid); 2116 } 2117 } 2118 2119 void os::print_os_info_brief(outputStream* st) { 2120 os::Linux::print_distro_info(st); 2121 2122 os::Posix::print_uname_info(st); 2123 2124 os::Linux::print_libversion_info(st); 2125 2126 } 2127 2128 void os::print_os_info(outputStream* st) { 2129 st->print("OS:"); 2130 2131 os::Linux::print_distro_info(st); 2132 2133 os::Posix::print_uname_info(st); 2134 2135 // Print warning if unsafe chroot environment detected 2136 if (unsafe_chroot_detected) { 2137 st->print("WARNING!! "); 2138 st->print_cr(unstable_chroot_error); 2139 } 2140 2141 os::Linux::print_libversion_info(st); 2142 2143 os::Posix::print_rlimit_info(st); 2144 2145 os::Posix::print_load_average(st); 2146 2147 os::Linux::print_full_memory_info(st); 2148 } 2149 2150 // Try to identify popular distros. 2151 // Most Linux distributions have a /etc/XXX-release file, which contains 2152 // the OS version string. Newer Linux distributions have a /etc/lsb-release 2153 // file that also contains the OS version string. Some have more than one 2154 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2155 // /etc/redhat-release.), so the order is important. 2156 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2157 // their own specific XXX-release file as well as a redhat-release file. 2158 // Because of this the XXX-release file needs to be searched for before the 2159 // redhat-release file. 2160 // Since Red Hat has a lsb-release file that is not very descriptive the 2161 // search for redhat-release needs to be before lsb-release. 2162 // Since the lsb-release file is the new standard it needs to be searched 2163 // before the older style release files. 2164 // Searching system-release (Red Hat) and os-release (other Linuxes) are a 2165 // next to last resort. The os-release file is a new standard that contains 2166 // distribution information and the system-release file seems to be an old 2167 // standard that has been replaced by the lsb-release and os-release files. 2168 // Searching for the debian_version file is the last resort. It contains 2169 // an informative string like "6.0.6" or "wheezy/sid". Because of this 2170 // "Debian " is printed before the contents of the debian_version file. 2171 void os::Linux::print_distro_info(outputStream* st) { 2172 if (!_print_ascii_file("/etc/oracle-release", st) && 2173 !_print_ascii_file("/etc/mandriva-release", st) && 2174 !_print_ascii_file("/etc/mandrake-release", st) && 2175 !_print_ascii_file("/etc/sun-release", st) && 2176 !_print_ascii_file("/etc/redhat-release", st) && 2177 !_print_ascii_file("/etc/lsb-release", st) && 2178 !_print_ascii_file("/etc/SuSE-release", st) && 2179 !_print_ascii_file("/etc/turbolinux-release", st) && 2180 !_print_ascii_file("/etc/gentoo-release", st) && 2181 !_print_ascii_file("/etc/ltib-release", st) && 2182 !_print_ascii_file("/etc/angstrom-version", st) && 2183 !_print_ascii_file("/etc/system-release", st) && 2184 !_print_ascii_file("/etc/os-release", st)) { 2185 2186 if (file_exists("/etc/debian_version")) { 2187 st->print("Debian "); 2188 _print_ascii_file("/etc/debian_version", st); 2189 } else { 2190 st->print("Linux"); 2191 } 2192 } 2193 st->cr(); 2194 } 2195 2196 void os::Linux::print_libversion_info(outputStream* st) { 2197 // libc, pthread 2198 st->print("libc:"); 2199 st->print(os::Linux::glibc_version()); st->print(" "); 2200 st->print(os::Linux::libpthread_version()); st->print(" "); 2201 if (os::Linux::is_LinuxThreads()) { 2202 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2203 } 2204 st->cr(); 2205 } 2206 2207 void os::Linux::print_full_memory_info(outputStream* st) { 2208 st->print("\n/proc/meminfo:\n"); 2209 _print_ascii_file("/proc/meminfo", st); 2210 st->cr(); 2211 } 2212 2213 void os::print_memory_info(outputStream* st) { 2214 2215 st->print("Memory:"); 2216 st->print(" %dk page", os::vm_page_size()>>10); 2217 2218 // values in struct sysinfo are "unsigned long" 2219 struct sysinfo si; 2220 sysinfo(&si); 2221 2222 st->print(", physical " UINT64_FORMAT "k", 2223 os::physical_memory() >> 10); 2224 st->print("(" UINT64_FORMAT "k free)", 2225 os::available_memory() >> 10); 2226 st->print(", swap " UINT64_FORMAT "k", 2227 ((jlong)si.totalswap * si.mem_unit) >> 10); 2228 st->print("(" UINT64_FORMAT "k free)", 2229 ((jlong)si.freeswap * si.mem_unit) >> 10); 2230 st->cr(); 2231 } 2232 2233 void os::pd_print_cpu_info(outputStream* st) { 2234 st->print("\n/proc/cpuinfo:\n"); 2235 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2236 st->print(" <Not Available>"); 2237 } 2238 st->cr(); 2239 } 2240 2241 void os::print_siginfo(outputStream* st, void* siginfo) { 2242 const siginfo_t* si = (const siginfo_t*)siginfo; 2243 2244 os::Posix::print_siginfo_brief(st, si); 2245 2246 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2247 UseSharedSpaces) { 2248 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2249 if (mapinfo->is_in_shared_space(si->si_addr)) { 2250 st->print("\n\nError accessing class data sharing archive." \ 2251 " Mapped file inaccessible during execution, " \ 2252 " possible disk/network problem."); 2253 } 2254 } 2255 st->cr(); 2256 } 2257 2258 2259 static void print_signal_handler(outputStream* st, int sig, 2260 char* buf, size_t buflen); 2261 2262 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2263 st->print_cr("Signal Handlers:"); 2264 print_signal_handler(st, SIGSEGV, buf, buflen); 2265 print_signal_handler(st, SIGBUS , buf, buflen); 2266 print_signal_handler(st, SIGFPE , buf, buflen); 2267 print_signal_handler(st, SIGPIPE, buf, buflen); 2268 print_signal_handler(st, SIGXFSZ, buf, buflen); 2269 print_signal_handler(st, SIGILL , buf, buflen); 2270 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2271 print_signal_handler(st, SR_signum, buf, buflen); 2272 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2273 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2274 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2275 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2276 #if defined(PPC64) 2277 print_signal_handler(st, SIGTRAP, buf, buflen); 2278 #endif 2279 } 2280 2281 static char saved_jvm_path[MAXPATHLEN] = {0}; 2282 2283 // Find the full path to the current module, libjvm.so 2284 void os::jvm_path(char *buf, jint buflen) { 2285 // Error checking. 2286 if (buflen < MAXPATHLEN) { 2287 assert(false, "must use a large-enough buffer"); 2288 buf[0] = '\0'; 2289 return; 2290 } 2291 // Lazy resolve the path to current module. 2292 if (saved_jvm_path[0] != 0) { 2293 strcpy(buf, saved_jvm_path); 2294 return; 2295 } 2296 2297 char dli_fname[MAXPATHLEN]; 2298 bool ret = dll_address_to_library_name( 2299 CAST_FROM_FN_PTR(address, os::jvm_path), 2300 dli_fname, sizeof(dli_fname), NULL); 2301 assert(ret, "cannot locate libjvm"); 2302 char *rp = NULL; 2303 if (ret && dli_fname[0] != '\0') { 2304 rp = realpath(dli_fname, buf); 2305 } 2306 if (rp == NULL) 2307 return; 2308 2309 if (Arguments::sun_java_launcher_is_altjvm()) { 2310 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical 2311 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". 2312 // If "/jre/lib/" appears at the right place in the string, then 2313 // assume we are installed in a JDK and we're done. Otherwise, check 2314 // for a JAVA_HOME environment variable and fix up the path so it 2315 // looks like libjvm.so is installed there (append a fake suffix 2316 // hotspot/libjvm.so). 2317 const char *p = buf + strlen(buf) - 1; 2318 for (int count = 0; p > buf && count < 5; ++count) { 2319 for (--p; p > buf && *p != '/'; --p) 2320 /* empty */ ; 2321 } 2322 2323 if (strncmp(p, "/jre/lib/", 9) != 0) { 2324 // Look for JAVA_HOME in the environment. 2325 char* java_home_var = ::getenv("JAVA_HOME"); 2326 if (java_home_var != NULL && java_home_var[0] != 0) { 2327 char* jrelib_p; 2328 int len; 2329 2330 // Check the current module name "libjvm.so". 2331 p = strrchr(buf, '/'); 2332 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2333 2334 rp = realpath(java_home_var, buf); 2335 if (rp == NULL) 2336 return; 2337 2338 // determine if this is a legacy image or modules image 2339 // modules image doesn't have "jre" subdirectory 2340 len = strlen(buf); 2341 jrelib_p = buf + len; 2342 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2343 if (0 != access(buf, F_OK)) { 2344 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2345 } 2346 2347 if (0 == access(buf, F_OK)) { 2348 // Use current module name "libjvm.so" 2349 len = strlen(buf); 2350 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2351 } else { 2352 // Go back to path of .so 2353 rp = realpath(dli_fname, buf); 2354 if (rp == NULL) 2355 return; 2356 } 2357 } 2358 } 2359 } 2360 2361 strcpy(saved_jvm_path, buf); 2362 } 2363 2364 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2365 // no prefix required, not even "_" 2366 } 2367 2368 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2369 // no suffix required 2370 } 2371 2372 //////////////////////////////////////////////////////////////////////////////// 2373 // sun.misc.Signal support 2374 2375 static volatile jint sigint_count = 0; 2376 2377 static void 2378 UserHandler(int sig, void *siginfo, void *context) { 2379 // 4511530 - sem_post is serialized and handled by the manager thread. When 2380 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2381 // don't want to flood the manager thread with sem_post requests. 2382 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2383 return; 2384 2385 // Ctrl-C is pressed during error reporting, likely because the error 2386 // handler fails to abort. Let VM die immediately. 2387 if (sig == SIGINT && is_error_reported()) { 2388 os::die(); 2389 } 2390 2391 os::signal_notify(sig); 2392 } 2393 2394 void* os::user_handler() { 2395 return CAST_FROM_FN_PTR(void*, UserHandler); 2396 } 2397 2398 class Semaphore : public StackObj { 2399 public: 2400 Semaphore(); 2401 ~Semaphore(); 2402 void signal(); 2403 void wait(); 2404 bool trywait(); 2405 bool timedwait(unsigned int sec, int nsec); 2406 private: 2407 sem_t _semaphore; 2408 }; 2409 2410 2411 Semaphore::Semaphore() { 2412 sem_init(&_semaphore, 0, 0); 2413 } 2414 2415 Semaphore::~Semaphore() { 2416 sem_destroy(&_semaphore); 2417 } 2418 2419 void Semaphore::signal() { 2420 sem_post(&_semaphore); 2421 } 2422 2423 void Semaphore::wait() { 2424 sem_wait(&_semaphore); 2425 } 2426 2427 bool Semaphore::trywait() { 2428 return sem_trywait(&_semaphore) == 0; 2429 } 2430 2431 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2432 struct timespec ts; 2433 unpackTime(&ts, false, (sec * NANOSECS_PER_SEC) + nsec); 2434 2435 while (1) { 2436 int result = sem_timedwait(&_semaphore, &ts); 2437 if (result == 0) { 2438 return true; 2439 } else if (errno == EINTR) { 2440 continue; 2441 } else if (errno == ETIMEDOUT) { 2442 return false; 2443 } else { 2444 return false; 2445 } 2446 } 2447 } 2448 2449 extern "C" { 2450 typedef void (*sa_handler_t)(int); 2451 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2452 } 2453 2454 void* os::signal(int signal_number, void* handler) { 2455 struct sigaction sigAct, oldSigAct; 2456 2457 sigfillset(&(sigAct.sa_mask)); 2458 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2459 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2460 2461 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2462 // -1 means registration failed 2463 return (void *)-1; 2464 } 2465 2466 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2467 } 2468 2469 void os::signal_raise(int signal_number) { 2470 ::raise(signal_number); 2471 } 2472 2473 /* 2474 * The following code is moved from os.cpp for making this 2475 * code platform specific, which it is by its very nature. 2476 */ 2477 2478 // Will be modified when max signal is changed to be dynamic 2479 int os::sigexitnum_pd() { 2480 return NSIG; 2481 } 2482 2483 // a counter for each possible signal value 2484 static volatile jint pending_signals[NSIG+1] = { 0 }; 2485 2486 // Linux(POSIX) specific hand shaking semaphore. 2487 static sem_t sig_sem; 2488 static Semaphore sr_semaphore; 2489 2490 void os::signal_init_pd() { 2491 // Initialize signal structures 2492 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2493 2494 // Initialize signal semaphore 2495 ::sem_init(&sig_sem, 0, 0); 2496 } 2497 2498 void os::signal_notify(int sig) { 2499 Atomic::inc(&pending_signals[sig]); 2500 ::sem_post(&sig_sem); 2501 } 2502 2503 static int check_pending_signals(bool wait) { 2504 Atomic::store(0, &sigint_count); 2505 for (;;) { 2506 for (int i = 0; i < NSIG + 1; i++) { 2507 jint n = pending_signals[i]; 2508 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2509 return i; 2510 } 2511 } 2512 if (!wait) { 2513 return -1; 2514 } 2515 JavaThread *thread = JavaThread::current(); 2516 ThreadBlockInVM tbivm(thread); 2517 2518 bool threadIsSuspended; 2519 do { 2520 thread->set_suspend_equivalent(); 2521 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2522 ::sem_wait(&sig_sem); 2523 2524 // were we externally suspended while we were waiting? 2525 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2526 if (threadIsSuspended) { 2527 // 2528 // The semaphore has been incremented, but while we were waiting 2529 // another thread suspended us. We don't want to continue running 2530 // while suspended because that would surprise the thread that 2531 // suspended us. 2532 // 2533 ::sem_post(&sig_sem); 2534 2535 thread->java_suspend_self(); 2536 } 2537 } while (threadIsSuspended); 2538 } 2539 } 2540 2541 int os::signal_lookup() { 2542 return check_pending_signals(false); 2543 } 2544 2545 int os::signal_wait() { 2546 return check_pending_signals(true); 2547 } 2548 2549 //////////////////////////////////////////////////////////////////////////////// 2550 // Virtual Memory 2551 2552 int os::vm_page_size() { 2553 // Seems redundant as all get out 2554 assert(os::Linux::page_size() != -1, "must call os::init"); 2555 return os::Linux::page_size(); 2556 } 2557 2558 // Solaris allocates memory by pages. 2559 int os::vm_allocation_granularity() { 2560 assert(os::Linux::page_size() != -1, "must call os::init"); 2561 return os::Linux::page_size(); 2562 } 2563 2564 // Rationale behind this function: 2565 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2566 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2567 // samples for JITted code. Here we create private executable mapping over the code cache 2568 // and then we can use standard (well, almost, as mapping can change) way to provide 2569 // info for the reporting script by storing timestamp and location of symbol 2570 void linux_wrap_code(char* base, size_t size) { 2571 static volatile jint cnt = 0; 2572 2573 if (!UseOprofile) { 2574 return; 2575 } 2576 2577 char buf[PATH_MAX+1]; 2578 int num = Atomic::add(1, &cnt); 2579 2580 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2581 os::get_temp_directory(), os::current_process_id(), num); 2582 unlink(buf); 2583 2584 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2585 2586 if (fd != -1) { 2587 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2588 if (rv != (off_t)-1) { 2589 if (::write(fd, "", 1) == 1) { 2590 mmap(base, size, 2591 PROT_READ|PROT_WRITE|PROT_EXEC, 2592 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2593 } 2594 } 2595 ::close(fd); 2596 unlink(buf); 2597 } 2598 } 2599 2600 static bool recoverable_mmap_error(int err) { 2601 // See if the error is one we can let the caller handle. This 2602 // list of errno values comes from JBS-6843484. I can't find a 2603 // Linux man page that documents this specific set of errno 2604 // values so while this list currently matches Solaris, it may 2605 // change as we gain experience with this failure mode. 2606 switch (err) { 2607 case EBADF: 2608 case EINVAL: 2609 case ENOTSUP: 2610 // let the caller deal with these errors 2611 return true; 2612 2613 default: 2614 // Any remaining errors on this OS can cause our reserved mapping 2615 // to be lost. That can cause confusion where different data 2616 // structures think they have the same memory mapped. The worst 2617 // scenario is if both the VM and a library think they have the 2618 // same memory mapped. 2619 return false; 2620 } 2621 } 2622 2623 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2624 int err) { 2625 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2626 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2627 strerror(err), err); 2628 } 2629 2630 static void warn_fail_commit_memory(char* addr, size_t size, 2631 size_t alignment_hint, bool exec, 2632 int err) { 2633 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2634 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2635 alignment_hint, exec, strerror(err), err); 2636 } 2637 2638 // NOTE: Linux kernel does not really reserve the pages for us. 2639 // All it does is to check if there are enough free pages 2640 // left at the time of mmap(). This could be a potential 2641 // problem. 2642 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2643 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2644 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2645 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2646 if (res != (uintptr_t) MAP_FAILED) { 2647 if (UseNUMAInterleaving) { 2648 numa_make_global(addr, size); 2649 } 2650 return 0; 2651 } 2652 2653 int err = errno; // save errno from mmap() call above 2654 2655 if (!recoverable_mmap_error(err)) { 2656 warn_fail_commit_memory(addr, size, exec, err); 2657 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2658 } 2659 2660 return err; 2661 } 2662 2663 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2664 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2665 } 2666 2667 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2668 const char* mesg) { 2669 assert(mesg != NULL, "mesg must be specified"); 2670 int err = os::Linux::commit_memory_impl(addr, size, exec); 2671 if (err != 0) { 2672 // the caller wants all commit errors to exit with the specified mesg: 2673 warn_fail_commit_memory(addr, size, exec, err); 2674 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2675 } 2676 } 2677 2678 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2679 #ifndef MAP_HUGETLB 2680 #define MAP_HUGETLB 0x40000 2681 #endif 2682 2683 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2684 #ifndef MADV_HUGEPAGE 2685 #define MADV_HUGEPAGE 14 2686 #endif 2687 2688 int os::Linux::commit_memory_impl(char* addr, size_t size, 2689 size_t alignment_hint, bool exec) { 2690 int err = os::Linux::commit_memory_impl(addr, size, exec); 2691 if (err == 0) { 2692 realign_memory(addr, size, alignment_hint); 2693 } 2694 return err; 2695 } 2696 2697 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2698 bool exec) { 2699 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2700 } 2701 2702 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2703 size_t alignment_hint, bool exec, 2704 const char* mesg) { 2705 assert(mesg != NULL, "mesg must be specified"); 2706 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2707 if (err != 0) { 2708 // the caller wants all commit errors to exit with the specified mesg: 2709 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2710 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2711 } 2712 } 2713 2714 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2715 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2716 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2717 // be supported or the memory may already be backed by huge pages. 2718 ::madvise(addr, bytes, MADV_HUGEPAGE); 2719 } 2720 } 2721 2722 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2723 // This method works by doing an mmap over an existing mmaping and effectively discarding 2724 // the existing pages. However it won't work for SHM-based large pages that cannot be 2725 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2726 // small pages on top of the SHM segment. This method always works for small pages, so we 2727 // allow that in any case. 2728 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2729 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2730 } 2731 } 2732 2733 void os::numa_make_global(char *addr, size_t bytes) { 2734 Linux::numa_interleave_memory(addr, bytes); 2735 } 2736 2737 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2738 // bind policy to MPOL_PREFERRED for the current thread. 2739 #define USE_MPOL_PREFERRED 0 2740 2741 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2742 // To make NUMA and large pages more robust when both enabled, we need to ease 2743 // the requirements on where the memory should be allocated. MPOL_BIND is the 2744 // default policy and it will force memory to be allocated on the specified 2745 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2746 // the specified node, but will not force it. Using this policy will prevent 2747 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2748 // free large pages. 2749 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2750 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2751 } 2752 2753 bool os::numa_topology_changed() { return false; } 2754 2755 size_t os::numa_get_groups_num() { 2756 int max_node = Linux::numa_max_node(); 2757 return max_node > 0 ? max_node + 1 : 1; 2758 } 2759 2760 int os::numa_get_group_id() { 2761 int cpu_id = Linux::sched_getcpu(); 2762 if (cpu_id != -1) { 2763 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2764 if (lgrp_id != -1) { 2765 return lgrp_id; 2766 } 2767 } 2768 return 0; 2769 } 2770 2771 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2772 for (size_t i = 0; i < size; i++) { 2773 ids[i] = i; 2774 } 2775 return size; 2776 } 2777 2778 bool os::get_page_info(char *start, page_info* info) { 2779 return false; 2780 } 2781 2782 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2783 return end; 2784 } 2785 2786 2787 int os::Linux::sched_getcpu_syscall(void) { 2788 unsigned int cpu; 2789 int retval = -1; 2790 2791 #if defined(IA32) 2792 # ifndef SYS_getcpu 2793 # define SYS_getcpu 318 2794 # endif 2795 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2796 #elif defined(AMD64) 2797 // Unfortunately we have to bring all these macros here from vsyscall.h 2798 // to be able to compile on old linuxes. 2799 # define __NR_vgetcpu 2 2800 # define VSYSCALL_START (-10UL << 20) 2801 # define VSYSCALL_SIZE 1024 2802 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2803 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2804 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2805 retval = vgetcpu(&cpu, NULL, NULL); 2806 #endif 2807 2808 return (retval == -1) ? retval : cpu; 2809 } 2810 2811 // Something to do with the numa-aware allocator needs these symbols 2812 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2813 extern "C" JNIEXPORT void numa_error(char *where) { } 2814 extern "C" JNIEXPORT int fork1() { return fork(); } 2815 2816 2817 // If we are running with libnuma version > 2, then we should 2818 // be trying to use symbols with versions 1.1 2819 // If we are running with earlier version, which did not have symbol versions, 2820 // we should use the base version. 2821 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2822 void *f = dlvsym(handle, name, "libnuma_1.1"); 2823 if (f == NULL) { 2824 f = dlsym(handle, name); 2825 } 2826 return f; 2827 } 2828 2829 bool os::Linux::libnuma_init() { 2830 // sched_getcpu() should be in libc. 2831 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2832 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2833 2834 // If it's not, try a direct syscall. 2835 if (sched_getcpu() == -1) 2836 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall)); 2837 2838 if (sched_getcpu() != -1) { // Does it work? 2839 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2840 if (handle != NULL) { 2841 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2842 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2843 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2844 libnuma_dlsym(handle, "numa_max_node"))); 2845 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2846 libnuma_dlsym(handle, "numa_available"))); 2847 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2848 libnuma_dlsym(handle, "numa_tonode_memory"))); 2849 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2850 libnuma_dlsym(handle, "numa_interleave_memory"))); 2851 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2852 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2853 2854 2855 if (numa_available() != -1) { 2856 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2857 // Create a cpu -> node mapping 2858 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2859 rebuild_cpu_to_node_map(); 2860 return true; 2861 } 2862 } 2863 } 2864 return false; 2865 } 2866 2867 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2868 // The table is later used in get_node_by_cpu(). 2869 void os::Linux::rebuild_cpu_to_node_map() { 2870 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2871 // in libnuma (possible values are starting from 16, 2872 // and continuing up with every other power of 2, but less 2873 // than the maximum number of CPUs supported by kernel), and 2874 // is a subject to change (in libnuma version 2 the requirements 2875 // are more reasonable) we'll just hardcode the number they use 2876 // in the library. 2877 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2878 2879 size_t cpu_num = os::active_processor_count(); 2880 size_t cpu_map_size = NCPUS / BitsPerCLong; 2881 size_t cpu_map_valid_size = 2882 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2883 2884 cpu_to_node()->clear(); 2885 cpu_to_node()->at_grow(cpu_num - 1); 2886 size_t node_num = numa_get_groups_num(); 2887 2888 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2889 for (size_t i = 0; i < node_num; i++) { 2890 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2891 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2892 if (cpu_map[j] != 0) { 2893 for (size_t k = 0; k < BitsPerCLong; k++) { 2894 if (cpu_map[j] & (1UL << k)) { 2895 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2896 } 2897 } 2898 } 2899 } 2900 } 2901 } 2902 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal); 2903 } 2904 2905 int os::Linux::get_node_by_cpu(int cpu_id) { 2906 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2907 return cpu_to_node()->at(cpu_id); 2908 } 2909 return -1; 2910 } 2911 2912 GrowableArray<int>* os::Linux::_cpu_to_node; 2913 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2914 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2915 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2916 os::Linux::numa_available_func_t os::Linux::_numa_available; 2917 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2918 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2919 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2920 unsigned long* os::Linux::_numa_all_nodes; 2921 2922 bool os::pd_uncommit_memory(char* addr, size_t size) { 2923 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2924 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2925 return res != (uintptr_t) MAP_FAILED; 2926 } 2927 2928 static 2929 address get_stack_commited_bottom(address bottom, size_t size) { 2930 address nbot = bottom; 2931 address ntop = bottom + size; 2932 2933 size_t page_sz = os::vm_page_size(); 2934 unsigned pages = size / page_sz; 2935 2936 unsigned char vec[1]; 2937 unsigned imin = 1, imax = pages + 1, imid; 2938 int mincore_return_value = 0; 2939 2940 assert(imin <= imax, "Unexpected page size"); 2941 2942 while (imin < imax) { 2943 imid = (imax + imin) / 2; 2944 nbot = ntop - (imid * page_sz); 2945 2946 // Use a trick with mincore to check whether the page is mapped or not. 2947 // mincore sets vec to 1 if page resides in memory and to 0 if page 2948 // is swapped output but if page we are asking for is unmapped 2949 // it returns -1,ENOMEM 2950 mincore_return_value = mincore(nbot, page_sz, vec); 2951 2952 if (mincore_return_value == -1) { 2953 // Page is not mapped go up 2954 // to find first mapped page 2955 if (errno != EAGAIN) { 2956 assert(errno == ENOMEM, "Unexpected mincore errno"); 2957 imax = imid; 2958 } 2959 } else { 2960 // Page is mapped go down 2961 // to find first not mapped page 2962 imin = imid + 1; 2963 } 2964 } 2965 2966 nbot = nbot + page_sz; 2967 2968 // Adjust stack bottom one page up if last checked page is not mapped 2969 if (mincore_return_value == -1) { 2970 nbot = nbot + page_sz; 2971 } 2972 2973 return nbot; 2974 } 2975 2976 2977 // Linux uses a growable mapping for the stack, and if the mapping for 2978 // the stack guard pages is not removed when we detach a thread the 2979 // stack cannot grow beyond the pages where the stack guard was 2980 // mapped. If at some point later in the process the stack expands to 2981 // that point, the Linux kernel cannot expand the stack any further 2982 // because the guard pages are in the way, and a segfault occurs. 2983 // 2984 // However, it's essential not to split the stack region by unmapping 2985 // a region (leaving a hole) that's already part of the stack mapping, 2986 // so if the stack mapping has already grown beyond the guard pages at 2987 // the time we create them, we have to truncate the stack mapping. 2988 // So, we need to know the extent of the stack mapping when 2989 // create_stack_guard_pages() is called. 2990 2991 // We only need this for stacks that are growable: at the time of 2992 // writing thread stacks don't use growable mappings (i.e. those 2993 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 2994 // only applies to the main thread. 2995 2996 // If the (growable) stack mapping already extends beyond the point 2997 // where we're going to put our guard pages, truncate the mapping at 2998 // that point by munmap()ping it. This ensures that when we later 2999 // munmap() the guard pages we don't leave a hole in the stack 3000 // mapping. This only affects the main/initial thread 3001 3002 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3003 3004 if (os::Linux::is_initial_thread()) { 3005 // As we manually grow stack up to bottom inside create_attached_thread(), 3006 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3007 // we don't need to do anything special. 3008 // Check it first, before calling heavy function. 3009 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3010 unsigned char vec[1]; 3011 3012 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3013 // Fallback to slow path on all errors, including EAGAIN 3014 stack_extent = (uintptr_t) get_stack_commited_bottom( 3015 os::Linux::initial_thread_stack_bottom(), 3016 (size_t)addr - stack_extent); 3017 } 3018 3019 if (stack_extent < (uintptr_t)addr) { 3020 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3021 } 3022 } 3023 3024 return os::commit_memory(addr, size, !ExecMem); 3025 } 3026 3027 // If this is a growable mapping, remove the guard pages entirely by 3028 // munmap()ping them. If not, just call uncommit_memory(). This only 3029 // affects the main/initial thread, but guard against future OS changes 3030 // It's safe to always unmap guard pages for initial thread because we 3031 // always place it right after end of the mapped region 3032 3033 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3034 uintptr_t stack_extent, stack_base; 3035 3036 if (os::Linux::is_initial_thread()) { 3037 return ::munmap(addr, size) == 0; 3038 } 3039 3040 return os::uncommit_memory(addr, size); 3041 } 3042 3043 static address _highest_vm_reserved_address = NULL; 3044 3045 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3046 // at 'requested_addr'. If there are existing memory mappings at the same 3047 // location, however, they will be overwritten. If 'fixed' is false, 3048 // 'requested_addr' is only treated as a hint, the return value may or 3049 // may not start from the requested address. Unlike Linux mmap(), this 3050 // function returns NULL to indicate failure. 3051 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3052 char * addr; 3053 int flags; 3054 3055 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3056 if (fixed) { 3057 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3058 flags |= MAP_FIXED; 3059 } 3060 3061 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3062 // touch an uncommitted page. Otherwise, the read/write might 3063 // succeed if we have enough swap space to back the physical page. 3064 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3065 flags, -1, 0); 3066 3067 if (addr != MAP_FAILED) { 3068 // anon_mmap() should only get called during VM initialization, 3069 // don't need lock (actually we can skip locking even it can be called 3070 // from multiple threads, because _highest_vm_reserved_address is just a 3071 // hint about the upper limit of non-stack memory regions.) 3072 if ((address)addr + bytes > _highest_vm_reserved_address) { 3073 _highest_vm_reserved_address = (address)addr + bytes; 3074 } 3075 } 3076 3077 return addr == MAP_FAILED ? NULL : addr; 3078 } 3079 3080 // Don't update _highest_vm_reserved_address, because there might be memory 3081 // regions above addr + size. If so, releasing a memory region only creates 3082 // a hole in the address space, it doesn't help prevent heap-stack collision. 3083 // 3084 static int anon_munmap(char * addr, size_t size) { 3085 return ::munmap(addr, size) == 0; 3086 } 3087 3088 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3089 size_t alignment_hint) { 3090 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3091 } 3092 3093 bool os::pd_release_memory(char* addr, size_t size) { 3094 return anon_munmap(addr, size); 3095 } 3096 3097 static address highest_vm_reserved_address() { 3098 return _highest_vm_reserved_address; 3099 } 3100 3101 static bool linux_mprotect(char* addr, size_t size, int prot) { 3102 // Linux wants the mprotect address argument to be page aligned. 3103 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3104 3105 // According to SUSv3, mprotect() should only be used with mappings 3106 // established by mmap(), and mmap() always maps whole pages. Unaligned 3107 // 'addr' likely indicates problem in the VM (e.g. trying to change 3108 // protection of malloc'ed or statically allocated memory). Check the 3109 // caller if you hit this assert. 3110 assert(addr == bottom, "sanity check"); 3111 3112 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3113 return ::mprotect(bottom, size, prot) == 0; 3114 } 3115 3116 // Set protections specified 3117 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3118 bool is_committed) { 3119 unsigned int p = 0; 3120 switch (prot) { 3121 case MEM_PROT_NONE: p = PROT_NONE; break; 3122 case MEM_PROT_READ: p = PROT_READ; break; 3123 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3124 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3125 default: 3126 ShouldNotReachHere(); 3127 } 3128 // is_committed is unused. 3129 return linux_mprotect(addr, bytes, p); 3130 } 3131 3132 bool os::guard_memory(char* addr, size_t size) { 3133 return linux_mprotect(addr, size, PROT_NONE); 3134 } 3135 3136 bool os::unguard_memory(char* addr, size_t size) { 3137 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3138 } 3139 3140 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) { 3141 bool result = false; 3142 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3143 MAP_ANONYMOUS|MAP_PRIVATE, 3144 -1, 0); 3145 if (p != MAP_FAILED) { 3146 void *aligned_p = align_ptr_up(p, page_size); 3147 3148 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3149 3150 munmap(p, page_size * 2); 3151 } 3152 3153 if (warn && !result) { 3154 warning("TransparentHugePages is not supported by the operating system."); 3155 } 3156 3157 return result; 3158 } 3159 3160 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3161 bool result = false; 3162 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3163 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3164 -1, 0); 3165 3166 if (p != MAP_FAILED) { 3167 // We don't know if this really is a huge page or not. 3168 FILE *fp = fopen("/proc/self/maps", "r"); 3169 if (fp) { 3170 while (!feof(fp)) { 3171 char chars[257]; 3172 long x = 0; 3173 if (fgets(chars, sizeof(chars), fp)) { 3174 if (sscanf(chars, "%lx-%*x", &x) == 1 3175 && x == (long)p) { 3176 if (strstr (chars, "hugepage")) { 3177 result = true; 3178 break; 3179 } 3180 } 3181 } 3182 } 3183 fclose(fp); 3184 } 3185 munmap(p, page_size); 3186 } 3187 3188 if (warn && !result) { 3189 warning("HugeTLBFS is not supported by the operating system."); 3190 } 3191 3192 return result; 3193 } 3194 3195 /* 3196 * Set the coredump_filter bits to include largepages in core dump (bit 6) 3197 * 3198 * From the coredump_filter documentation: 3199 * 3200 * - (bit 0) anonymous private memory 3201 * - (bit 1) anonymous shared memory 3202 * - (bit 2) file-backed private memory 3203 * - (bit 3) file-backed shared memory 3204 * - (bit 4) ELF header pages in file-backed private memory areas (it is 3205 * effective only if the bit 2 is cleared) 3206 * - (bit 5) hugetlb private memory 3207 * - (bit 6) hugetlb shared memory 3208 */ 3209 static void set_coredump_filter(void) { 3210 FILE *f; 3211 long cdm; 3212 3213 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3214 return; 3215 } 3216 3217 if (fscanf(f, "%lx", &cdm) != 1) { 3218 fclose(f); 3219 return; 3220 } 3221 3222 rewind(f); 3223 3224 if ((cdm & LARGEPAGES_BIT) == 0) { 3225 cdm |= LARGEPAGES_BIT; 3226 fprintf(f, "%#lx", cdm); 3227 } 3228 3229 fclose(f); 3230 } 3231 3232 // Large page support 3233 3234 static size_t _large_page_size = 0; 3235 3236 size_t os::Linux::find_large_page_size() { 3237 size_t large_page_size = 0; 3238 3239 // large_page_size on Linux is used to round up heap size. x86 uses either 3240 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3241 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3242 // page as large as 256M. 3243 // 3244 // Here we try to figure out page size by parsing /proc/meminfo and looking 3245 // for a line with the following format: 3246 // Hugepagesize: 2048 kB 3247 // 3248 // If we can't determine the value (e.g. /proc is not mounted, or the text 3249 // format has been changed), we'll use the largest page size supported by 3250 // the processor. 3251 3252 #ifndef ZERO 3253 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3254 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3255 #endif // ZERO 3256 3257 FILE *fp = fopen("/proc/meminfo", "r"); 3258 if (fp) { 3259 while (!feof(fp)) { 3260 int x = 0; 3261 char buf[16]; 3262 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3263 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3264 large_page_size = x * K; 3265 break; 3266 } 3267 } else { 3268 // skip to next line 3269 for (;;) { 3270 int ch = fgetc(fp); 3271 if (ch == EOF || ch == (int)'\n') break; 3272 } 3273 } 3274 } 3275 fclose(fp); 3276 } 3277 3278 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3279 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3280 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3281 proper_unit_for_byte_size(large_page_size)); 3282 } 3283 3284 return large_page_size; 3285 } 3286 3287 size_t os::Linux::setup_large_page_size() { 3288 _large_page_size = Linux::find_large_page_size(); 3289 const size_t default_page_size = (size_t)Linux::page_size(); 3290 if (_large_page_size > default_page_size) { 3291 _page_sizes[0] = _large_page_size; 3292 _page_sizes[1] = default_page_size; 3293 _page_sizes[2] = 0; 3294 } 3295 3296 return _large_page_size; 3297 } 3298 3299 bool os::Linux::setup_large_page_type(size_t page_size) { 3300 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3301 FLAG_IS_DEFAULT(UseSHM) && 3302 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3303 3304 // The type of large pages has not been specified by the user. 3305 3306 // Try UseHugeTLBFS and then UseSHM. 3307 UseHugeTLBFS = UseSHM = true; 3308 3309 // Don't try UseTransparentHugePages since there are known 3310 // performance issues with it turned on. This might change in the future. 3311 UseTransparentHugePages = false; 3312 } 3313 3314 if (UseTransparentHugePages) { 3315 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3316 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3317 UseHugeTLBFS = false; 3318 UseSHM = false; 3319 return true; 3320 } 3321 UseTransparentHugePages = false; 3322 } 3323 3324 if (UseHugeTLBFS) { 3325 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3326 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3327 UseSHM = false; 3328 return true; 3329 } 3330 UseHugeTLBFS = false; 3331 } 3332 3333 return UseSHM; 3334 } 3335 3336 void os::large_page_init() { 3337 if (!UseLargePages && 3338 !UseTransparentHugePages && 3339 !UseHugeTLBFS && 3340 !UseSHM) { 3341 // Not using large pages. 3342 return; 3343 } 3344 3345 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3346 // The user explicitly turned off large pages. 3347 // Ignore the rest of the large pages flags. 3348 UseTransparentHugePages = false; 3349 UseHugeTLBFS = false; 3350 UseSHM = false; 3351 return; 3352 } 3353 3354 size_t large_page_size = Linux::setup_large_page_size(); 3355 UseLargePages = Linux::setup_large_page_type(large_page_size); 3356 3357 set_coredump_filter(); 3358 } 3359 3360 #ifndef SHM_HUGETLB 3361 #define SHM_HUGETLB 04000 3362 #endif 3363 3364 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3365 // "exec" is passed in but not used. Creating the shared image for 3366 // the code cache doesn't have an SHM_X executable permission to check. 3367 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3368 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3369 3370 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3371 return NULL; // Fallback to small pages. 3372 } 3373 3374 key_t key = IPC_PRIVATE; 3375 char *addr; 3376 3377 bool warn_on_failure = UseLargePages && 3378 (!FLAG_IS_DEFAULT(UseLargePages) || 3379 !FLAG_IS_DEFAULT(UseSHM) || 3380 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 3381 ); 3382 char msg[128]; 3383 3384 // Create a large shared memory region to attach to based on size. 3385 // Currently, size is the total size of the heap 3386 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3387 if (shmid == -1) { 3388 // Possible reasons for shmget failure: 3389 // 1. shmmax is too small for Java heap. 3390 // > check shmmax value: cat /proc/sys/kernel/shmmax 3391 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3392 // 2. not enough large page memory. 3393 // > check available large pages: cat /proc/meminfo 3394 // > increase amount of large pages: 3395 // echo new_value > /proc/sys/vm/nr_hugepages 3396 // Note 1: different Linux may use different name for this property, 3397 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3398 // Note 2: it's possible there's enough physical memory available but 3399 // they are so fragmented after a long run that they can't 3400 // coalesce into large pages. Try to reserve large pages when 3401 // the system is still "fresh". 3402 if (warn_on_failure) { 3403 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3404 warning(msg); 3405 } 3406 return NULL; 3407 } 3408 3409 // attach to the region 3410 addr = (char*)shmat(shmid, req_addr, 0); 3411 int err = errno; 3412 3413 // Remove shmid. If shmat() is successful, the actual shared memory segment 3414 // will be deleted when it's detached by shmdt() or when the process 3415 // terminates. If shmat() is not successful this will remove the shared 3416 // segment immediately. 3417 shmctl(shmid, IPC_RMID, NULL); 3418 3419 if ((intptr_t)addr == -1) { 3420 if (warn_on_failure) { 3421 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3422 warning(msg); 3423 } 3424 return NULL; 3425 } 3426 3427 return addr; 3428 } 3429 3430 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) { 3431 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3432 3433 bool warn_on_failure = UseLargePages && 3434 (!FLAG_IS_DEFAULT(UseLargePages) || 3435 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3436 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3437 3438 if (warn_on_failure) { 3439 char msg[128]; 3440 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3441 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3442 warning(msg); 3443 } 3444 } 3445 3446 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) { 3447 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3448 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3449 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3450 3451 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3452 char* addr = (char*)::mmap(req_addr, bytes, prot, 3453 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3454 -1, 0); 3455 3456 if (addr == MAP_FAILED) { 3457 warn_on_large_pages_failure(req_addr, bytes, errno); 3458 return NULL; 3459 } 3460 3461 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3462 3463 return addr; 3464 } 3465 3466 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3467 size_t large_page_size = os::large_page_size(); 3468 3469 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3470 3471 // Allocate small pages. 3472 3473 char* start; 3474 if (req_addr != NULL) { 3475 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3476 assert(is_size_aligned(bytes, alignment), "Must be"); 3477 start = os::reserve_memory(bytes, req_addr); 3478 assert(start == NULL || start == req_addr, "Must be"); 3479 } else { 3480 start = os::reserve_memory_aligned(bytes, alignment); 3481 } 3482 3483 if (start == NULL) { 3484 return NULL; 3485 } 3486 3487 assert(is_ptr_aligned(start, alignment), "Must be"); 3488 3489 // os::reserve_memory_special will record this memory area. 3490 // Need to release it here to prevent overlapping reservations. 3491 MemTracker::record_virtual_memory_release((address)start, bytes); 3492 3493 char* end = start + bytes; 3494 3495 // Find the regions of the allocated chunk that can be promoted to large pages. 3496 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3497 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3498 3499 size_t lp_bytes = lp_end - lp_start; 3500 3501 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3502 3503 if (lp_bytes == 0) { 3504 // The mapped region doesn't even span the start and the end of a large page. 3505 // Fall back to allocate a non-special area. 3506 ::munmap(start, end - start); 3507 return NULL; 3508 } 3509 3510 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3511 3512 3513 void* result; 3514 3515 if (start != lp_start) { 3516 result = ::mmap(start, lp_start - start, prot, 3517 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3518 -1, 0); 3519 if (result == MAP_FAILED) { 3520 ::munmap(lp_start, end - lp_start); 3521 return NULL; 3522 } 3523 } 3524 3525 result = ::mmap(lp_start, lp_bytes, prot, 3526 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3527 -1, 0); 3528 if (result == MAP_FAILED) { 3529 warn_on_large_pages_failure(req_addr, bytes, errno); 3530 // If the mmap above fails, the large pages region will be unmapped and we 3531 // have regions before and after with small pages. Release these regions. 3532 // 3533 // | mapped | unmapped | mapped | 3534 // ^ ^ ^ ^ 3535 // start lp_start lp_end end 3536 // 3537 ::munmap(start, lp_start - start); 3538 ::munmap(lp_end, end - lp_end); 3539 return NULL; 3540 } 3541 3542 if (lp_end != end) { 3543 result = ::mmap(lp_end, end - lp_end, prot, 3544 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3545 -1, 0); 3546 if (result == MAP_FAILED) { 3547 ::munmap(start, lp_end - start); 3548 return NULL; 3549 } 3550 } 3551 3552 return start; 3553 } 3554 3555 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3556 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3557 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3558 assert(is_power_of_2(alignment), "Must be"); 3559 assert(is_power_of_2(os::large_page_size()), "Must be"); 3560 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3561 3562 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3563 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3564 } else { 3565 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3566 } 3567 } 3568 3569 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3570 assert(UseLargePages, "only for large pages"); 3571 3572 char* addr; 3573 if (UseSHM) { 3574 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3575 } else { 3576 assert(UseHugeTLBFS, "must be"); 3577 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3578 } 3579 3580 if (addr != NULL) { 3581 if (UseNUMAInterleaving) { 3582 numa_make_global(addr, bytes); 3583 } 3584 3585 // The memory is committed 3586 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, mtNone, CALLER_PC); 3587 } 3588 3589 return addr; 3590 } 3591 3592 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3593 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3594 return shmdt(base) == 0; 3595 } 3596 3597 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3598 return pd_release_memory(base, bytes); 3599 } 3600 3601 bool os::release_memory_special(char* base, size_t bytes) { 3602 assert(UseLargePages, "only for large pages"); 3603 3604 MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3605 3606 bool res; 3607 if (UseSHM) { 3608 res = os::Linux::release_memory_special_shm(base, bytes); 3609 } else { 3610 assert(UseHugeTLBFS, "must be"); 3611 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3612 } 3613 3614 if (res) { 3615 tkr.record((address)base, bytes); 3616 } else { 3617 tkr.discard(); 3618 } 3619 3620 return res; 3621 } 3622 3623 size_t os::large_page_size() { 3624 return _large_page_size; 3625 } 3626 3627 // With SysV SHM the entire memory region must be allocated as shared 3628 // memory. 3629 // HugeTLBFS allows application to commit large page memory on demand. 3630 // However, when committing memory with HugeTLBFS fails, the region 3631 // that was supposed to be committed will lose the old reservation 3632 // and allow other threads to steal that memory region. Because of this 3633 // behavior we can't commit HugeTLBFS memory. 3634 bool os::can_commit_large_page_memory() { 3635 return UseTransparentHugePages; 3636 } 3637 3638 bool os::can_execute_large_page_memory() { 3639 return UseTransparentHugePages || UseHugeTLBFS; 3640 } 3641 3642 // Reserve memory at an arbitrary address, only if that area is 3643 // available (and not reserved for something else). 3644 3645 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3646 const int max_tries = 10; 3647 char* base[max_tries]; 3648 size_t size[max_tries]; 3649 const size_t gap = 0x000000; 3650 3651 // Assert only that the size is a multiple of the page size, since 3652 // that's all that mmap requires, and since that's all we really know 3653 // about at this low abstraction level. If we need higher alignment, 3654 // we can either pass an alignment to this method or verify alignment 3655 // in one of the methods further up the call chain. See bug 5044738. 3656 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3657 3658 // Repeatedly allocate blocks until the block is allocated at the 3659 // right spot. Give up after max_tries. Note that reserve_memory() will 3660 // automatically update _highest_vm_reserved_address if the call is 3661 // successful. The variable tracks the highest memory address every reserved 3662 // by JVM. It is used to detect heap-stack collision if running with 3663 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3664 // space than needed, it could confuse the collision detecting code. To 3665 // solve the problem, save current _highest_vm_reserved_address and 3666 // calculate the correct value before return. 3667 address old_highest = _highest_vm_reserved_address; 3668 3669 // Linux mmap allows caller to pass an address as hint; give it a try first, 3670 // if kernel honors the hint then we can return immediately. 3671 char * addr = anon_mmap(requested_addr, bytes, false); 3672 if (addr == requested_addr) { 3673 return requested_addr; 3674 } 3675 3676 if (addr != NULL) { 3677 // mmap() is successful but it fails to reserve at the requested address 3678 anon_munmap(addr, bytes); 3679 } 3680 3681 int i; 3682 for (i = 0; i < max_tries; ++i) { 3683 base[i] = reserve_memory(bytes); 3684 3685 if (base[i] != NULL) { 3686 // Is this the block we wanted? 3687 if (base[i] == requested_addr) { 3688 size[i] = bytes; 3689 break; 3690 } 3691 3692 // Does this overlap the block we wanted? Give back the overlapped 3693 // parts and try again. 3694 3695 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3696 if (top_overlap >= 0 && top_overlap < bytes) { 3697 unmap_memory(base[i], top_overlap); 3698 base[i] += top_overlap; 3699 size[i] = bytes - top_overlap; 3700 } else { 3701 size_t bottom_overlap = base[i] + bytes - requested_addr; 3702 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3703 unmap_memory(requested_addr, bottom_overlap); 3704 size[i] = bytes - bottom_overlap; 3705 } else { 3706 size[i] = bytes; 3707 } 3708 } 3709 } 3710 } 3711 3712 // Give back the unused reserved pieces. 3713 3714 for (int j = 0; j < i; ++j) { 3715 if (base[j] != NULL) { 3716 unmap_memory(base[j], size[j]); 3717 } 3718 } 3719 3720 if (i < max_tries) { 3721 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3722 return requested_addr; 3723 } else { 3724 _highest_vm_reserved_address = old_highest; 3725 return NULL; 3726 } 3727 } 3728 3729 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3730 return ::read(fd, buf, nBytes); 3731 } 3732 3733 // 3734 // Short sleep, direct OS call. 3735 // 3736 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee 3737 // sched_yield(2) will actually give up the CPU: 3738 // 3739 // * Alone on this pariticular CPU, keeps running. 3740 // * Before the introduction of "skip_buddy" with "compat_yield" disabled 3741 // (pre 2.6.39). 3742 // 3743 // So calling this with 0 is an alternative. 3744 // 3745 void os::naked_short_sleep(jlong ms) { 3746 struct timespec req; 3747 3748 assert(ms < 1000, "Un-interruptable sleep, short time use only"); 3749 req.tv_sec = 0; 3750 if (ms > 0) { 3751 req.tv_nsec = (ms % 1000) * 1000000; 3752 } 3753 else { 3754 req.tv_nsec = 1; 3755 } 3756 3757 nanosleep(&req, NULL); 3758 3759 return; 3760 } 3761 3762 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3763 void os::infinite_sleep() { 3764 while (true) { // sleep forever ... 3765 ::sleep(100); // ... 100 seconds at a time 3766 } 3767 } 3768 3769 // Used to convert frequent JVM_Yield() to nops 3770 bool os::dont_yield() { 3771 return DontYieldALot; 3772 } 3773 3774 void os::yield() { 3775 sched_yield(); 3776 } 3777 3778 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 3779 3780 void os::yield_all(int attempts) { 3781 // Yields to all threads, including threads with lower priorities 3782 // Threads on Linux are all with same priority. The Solaris style 3783 // os::yield_all() with nanosleep(1ms) is not necessary. 3784 sched_yield(); 3785 } 3786 3787 // Called from the tight loops to possibly influence time-sharing heuristics 3788 void os::loop_breaker(int attempts) { 3789 os::yield_all(attempts); 3790 } 3791 3792 //////////////////////////////////////////////////////////////////////////////// 3793 // thread priority support 3794 3795 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3796 // only supports dynamic priority, static priority must be zero. For real-time 3797 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3798 // However, for large multi-threaded applications, SCHED_RR is not only slower 3799 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3800 // of 5 runs - Sep 2005). 3801 // 3802 // The following code actually changes the niceness of kernel-thread/LWP. It 3803 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3804 // not the entire user process, and user level threads are 1:1 mapped to kernel 3805 // threads. It has always been the case, but could change in the future. For 3806 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3807 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3808 3809 int os::java_to_os_priority[CriticalPriority + 1] = { 3810 19, // 0 Entry should never be used 3811 3812 4, // 1 MinPriority 3813 3, // 2 3814 2, // 3 3815 3816 1, // 4 3817 0, // 5 NormPriority 3818 -1, // 6 3819 3820 -2, // 7 3821 -3, // 8 3822 -4, // 9 NearMaxPriority 3823 3824 -5, // 10 MaxPriority 3825 3826 -5 // 11 CriticalPriority 3827 }; 3828 3829 static int prio_init() { 3830 if (ThreadPriorityPolicy == 1) { 3831 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3832 // if effective uid is not root. Perhaps, a more elegant way of doing 3833 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3834 if (geteuid() != 0) { 3835 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3836 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3837 } 3838 ThreadPriorityPolicy = 0; 3839 } 3840 } 3841 if (UseCriticalJavaThreadPriority) { 3842 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3843 } 3844 return 0; 3845 } 3846 3847 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3848 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 3849 3850 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3851 return (ret == 0) ? OS_OK : OS_ERR; 3852 } 3853 3854 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3855 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3856 *priority_ptr = java_to_os_priority[NormPriority]; 3857 return OS_OK; 3858 } 3859 3860 errno = 0; 3861 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3862 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3863 } 3864 3865 // Hint to the underlying OS that a task switch would not be good. 3866 // Void return because it's a hint and can fail. 3867 void os::hint_no_preempt() {} 3868 3869 //////////////////////////////////////////////////////////////////////////////// 3870 // suspend/resume support 3871 3872 // the low-level signal-based suspend/resume support is a remnant from the 3873 // old VM-suspension that used to be for java-suspension, safepoints etc, 3874 // within hotspot. Now there is a single use-case for this: 3875 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3876 // that runs in the watcher thread. 3877 // The remaining code is greatly simplified from the more general suspension 3878 // code that used to be used. 3879 // 3880 // The protocol is quite simple: 3881 // - suspend: 3882 // - sends a signal to the target thread 3883 // - polls the suspend state of the osthread using a yield loop 3884 // - target thread signal handler (SR_handler) sets suspend state 3885 // and blocks in sigsuspend until continued 3886 // - resume: 3887 // - sets target osthread state to continue 3888 // - sends signal to end the sigsuspend loop in the SR_handler 3889 // 3890 // Note that the SR_lock plays no role in this suspend/resume protocol. 3891 // 3892 3893 static void resume_clear_context(OSThread *osthread) { 3894 osthread->set_ucontext(NULL); 3895 osthread->set_siginfo(NULL); 3896 } 3897 3898 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 3899 osthread->set_ucontext(context); 3900 osthread->set_siginfo(siginfo); 3901 } 3902 3903 // 3904 // Handler function invoked when a thread's execution is suspended or 3905 // resumed. We have to be careful that only async-safe functions are 3906 // called here (Note: most pthread functions are not async safe and 3907 // should be avoided.) 3908 // 3909 // Note: sigwait() is a more natural fit than sigsuspend() from an 3910 // interface point of view, but sigwait() prevents the signal hander 3911 // from being run. libpthread would get very confused by not having 3912 // its signal handlers run and prevents sigwait()'s use with the 3913 // mutex granting granting signal. 3914 // 3915 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 3916 // 3917 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3918 // Save and restore errno to avoid confusing native code with EINTR 3919 // after sigsuspend. 3920 int old_errno = errno; 3921 3922 Thread* thread = Thread::current(); 3923 OSThread* osthread = thread->osthread(); 3924 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 3925 3926 os::SuspendResume::State current = osthread->sr.state(); 3927 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 3928 suspend_save_context(osthread, siginfo, context); 3929 3930 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 3931 os::SuspendResume::State state = osthread->sr.suspended(); 3932 if (state == os::SuspendResume::SR_SUSPENDED) { 3933 sigset_t suspend_set; // signals for sigsuspend() 3934 3935 // get current set of blocked signals and unblock resume signal 3936 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3937 sigdelset(&suspend_set, SR_signum); 3938 3939 sr_semaphore.signal(); 3940 // wait here until we are resumed 3941 while (1) { 3942 sigsuspend(&suspend_set); 3943 3944 os::SuspendResume::State result = osthread->sr.running(); 3945 if (result == os::SuspendResume::SR_RUNNING) { 3946 sr_semaphore.signal(); 3947 break; 3948 } 3949 } 3950 3951 } else if (state == os::SuspendResume::SR_RUNNING) { 3952 // request was cancelled, continue 3953 } else { 3954 ShouldNotReachHere(); 3955 } 3956 3957 resume_clear_context(osthread); 3958 } else if (current == os::SuspendResume::SR_RUNNING) { 3959 // request was cancelled, continue 3960 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 3961 // ignore 3962 } else { 3963 // ignore 3964 } 3965 3966 errno = old_errno; 3967 } 3968 3969 3970 static int SR_initialize() { 3971 struct sigaction act; 3972 char *s; 3973 /* Get signal number to use for suspend/resume */ 3974 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 3975 int sig = ::strtol(s, 0, 10); 3976 if (sig > 0 || sig < _NSIG) { 3977 SR_signum = sig; 3978 } 3979 } 3980 3981 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 3982 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 3983 3984 sigemptyset(&SR_sigset); 3985 sigaddset(&SR_sigset, SR_signum); 3986 3987 /* Set up signal handler for suspend/resume */ 3988 act.sa_flags = SA_RESTART|SA_SIGINFO; 3989 act.sa_handler = (void (*)(int)) SR_handler; 3990 3991 // SR_signum is blocked by default. 3992 // 4528190 - We also need to block pthread restart signal (32 on all 3993 // supported Linux platforms). Note that LinuxThreads need to block 3994 // this signal for all threads to work properly. So we don't have 3995 // to use hard-coded signal number when setting up the mask. 3996 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 3997 3998 if (sigaction(SR_signum, &act, 0) == -1) { 3999 return -1; 4000 } 4001 4002 // Save signal flag 4003 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4004 return 0; 4005 } 4006 4007 static int sr_notify(OSThread* osthread) { 4008 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4009 assert_status(status == 0, status, "pthread_kill"); 4010 return status; 4011 } 4012 4013 // "Randomly" selected value for how long we want to spin 4014 // before bailing out on suspending a thread, also how often 4015 // we send a signal to a thread we want to resume 4016 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4017 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4018 4019 // returns true on success and false on error - really an error is fatal 4020 // but this seems the normal response to library errors 4021 static bool do_suspend(OSThread* osthread) { 4022 assert(osthread->sr.is_running(), "thread should be running"); 4023 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4024 4025 // mark as suspended and send signal 4026 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4027 // failed to switch, state wasn't running? 4028 ShouldNotReachHere(); 4029 return false; 4030 } 4031 4032 if (sr_notify(osthread) != 0) { 4033 ShouldNotReachHere(); 4034 } 4035 4036 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4037 while (true) { 4038 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4039 break; 4040 } else { 4041 // timeout 4042 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4043 if (cancelled == os::SuspendResume::SR_RUNNING) { 4044 return false; 4045 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4046 // make sure that we consume the signal on the semaphore as well 4047 sr_semaphore.wait(); 4048 break; 4049 } else { 4050 ShouldNotReachHere(); 4051 return false; 4052 } 4053 } 4054 } 4055 4056 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4057 return true; 4058 } 4059 4060 static void do_resume(OSThread* osthread) { 4061 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4062 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4063 4064 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4065 // failed to switch to WAKEUP_REQUEST 4066 ShouldNotReachHere(); 4067 return; 4068 } 4069 4070 while (true) { 4071 if (sr_notify(osthread) == 0) { 4072 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4073 if (osthread->sr.is_running()) { 4074 return; 4075 } 4076 } 4077 } else { 4078 ShouldNotReachHere(); 4079 } 4080 } 4081 4082 guarantee(osthread->sr.is_running(), "Must be running!"); 4083 } 4084 4085 /////////////////////////////////////////////////////////////////////////////////// 4086 // signal handling (except suspend/resume) 4087 4088 // This routine may be used by user applications as a "hook" to catch signals. 4089 // The user-defined signal handler must pass unrecognized signals to this 4090 // routine, and if it returns true (non-zero), then the signal handler must 4091 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4092 // routine will never retun false (zero), but instead will execute a VM panic 4093 // routine kill the process. 4094 // 4095 // If this routine returns false, it is OK to call it again. This allows 4096 // the user-defined signal handler to perform checks either before or after 4097 // the VM performs its own checks. Naturally, the user code would be making 4098 // a serious error if it tried to handle an exception (such as a null check 4099 // or breakpoint) that the VM was generating for its own correct operation. 4100 // 4101 // This routine may recognize any of the following kinds of signals: 4102 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4103 // It should be consulted by handlers for any of those signals. 4104 // 4105 // The caller of this routine must pass in the three arguments supplied 4106 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4107 // field of the structure passed to sigaction(). This routine assumes that 4108 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4109 // 4110 // Note that the VM will print warnings if it detects conflicting signal 4111 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4112 // 4113 extern "C" JNIEXPORT int 4114 JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 4115 void* ucontext, int abort_if_unrecognized); 4116 4117 void signalHandler(int sig, siginfo_t* info, void* uc) { 4118 assert(info != NULL && uc != NULL, "it must be old kernel"); 4119 int orig_errno = errno; // Preserve errno value over signal handler. 4120 JVM_handle_linux_signal(sig, info, uc, true); 4121 errno = orig_errno; 4122 } 4123 4124 4125 // This boolean allows users to forward their own non-matching signals 4126 // to JVM_handle_linux_signal, harmlessly. 4127 bool os::Linux::signal_handlers_are_installed = false; 4128 4129 // For signal-chaining 4130 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4131 unsigned int os::Linux::sigs = 0; 4132 bool os::Linux::libjsig_is_loaded = false; 4133 typedef struct sigaction *(*get_signal_t)(int); 4134 get_signal_t os::Linux::get_signal_action = NULL; 4135 4136 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4137 struct sigaction *actp = NULL; 4138 4139 if (libjsig_is_loaded) { 4140 // Retrieve the old signal handler from libjsig 4141 actp = (*get_signal_action)(sig); 4142 } 4143 if (actp == NULL) { 4144 // Retrieve the preinstalled signal handler from jvm 4145 actp = get_preinstalled_handler(sig); 4146 } 4147 4148 return actp; 4149 } 4150 4151 static bool call_chained_handler(struct sigaction *actp, int sig, 4152 siginfo_t *siginfo, void *context) { 4153 // Call the old signal handler 4154 if (actp->sa_handler == SIG_DFL) { 4155 // It's more reasonable to let jvm treat it as an unexpected exception 4156 // instead of taking the default action. 4157 return false; 4158 } else if (actp->sa_handler != SIG_IGN) { 4159 if ((actp->sa_flags & SA_NODEFER) == 0) { 4160 // automaticlly block the signal 4161 sigaddset(&(actp->sa_mask), sig); 4162 } 4163 4164 sa_handler_t hand; 4165 sa_sigaction_t sa; 4166 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4167 // retrieve the chained handler 4168 if (siginfo_flag_set) { 4169 sa = actp->sa_sigaction; 4170 } else { 4171 hand = actp->sa_handler; 4172 } 4173 4174 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4175 actp->sa_handler = SIG_DFL; 4176 } 4177 4178 // try to honor the signal mask 4179 sigset_t oset; 4180 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4181 4182 // call into the chained handler 4183 if (siginfo_flag_set) { 4184 (*sa)(sig, siginfo, context); 4185 } else { 4186 (*hand)(sig); 4187 } 4188 4189 // restore the signal mask 4190 pthread_sigmask(SIG_SETMASK, &oset, 0); 4191 } 4192 // Tell jvm's signal handler the signal is taken care of. 4193 return true; 4194 } 4195 4196 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4197 bool chained = false; 4198 // signal-chaining 4199 if (UseSignalChaining) { 4200 struct sigaction *actp = get_chained_signal_action(sig); 4201 if (actp != NULL) { 4202 chained = call_chained_handler(actp, sig, siginfo, context); 4203 } 4204 } 4205 return chained; 4206 } 4207 4208 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4209 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 4210 return &sigact[sig]; 4211 } 4212 return NULL; 4213 } 4214 4215 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4216 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4217 sigact[sig] = oldAct; 4218 sigs |= (unsigned int)1 << sig; 4219 } 4220 4221 // for diagnostic 4222 int os::Linux::sigflags[MAXSIGNUM]; 4223 4224 int os::Linux::get_our_sigflags(int sig) { 4225 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4226 return sigflags[sig]; 4227 } 4228 4229 void os::Linux::set_our_sigflags(int sig, int flags) { 4230 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4231 sigflags[sig] = flags; 4232 } 4233 4234 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4235 // Check for overwrite. 4236 struct sigaction oldAct; 4237 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4238 4239 void* oldhand = oldAct.sa_sigaction 4240 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4241 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4242 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4243 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4244 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4245 if (AllowUserSignalHandlers || !set_installed) { 4246 // Do not overwrite; user takes responsibility to forward to us. 4247 return; 4248 } else if (UseSignalChaining) { 4249 // save the old handler in jvm 4250 save_preinstalled_handler(sig, oldAct); 4251 // libjsig also interposes the sigaction() call below and saves the 4252 // old sigaction on it own. 4253 } else { 4254 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4255 "%#lx for signal %d.", (long)oldhand, sig)); 4256 } 4257 } 4258 4259 struct sigaction sigAct; 4260 sigfillset(&(sigAct.sa_mask)); 4261 sigAct.sa_handler = SIG_DFL; 4262 if (!set_installed) { 4263 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4264 } else { 4265 sigAct.sa_sigaction = signalHandler; 4266 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4267 } 4268 // Save flags, which are set by ours 4269 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4270 sigflags[sig] = sigAct.sa_flags; 4271 4272 int ret = sigaction(sig, &sigAct, &oldAct); 4273 assert(ret == 0, "check"); 4274 4275 void* oldhand2 = oldAct.sa_sigaction 4276 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4277 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4278 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4279 } 4280 4281 // install signal handlers for signals that HotSpot needs to 4282 // handle in order to support Java-level exception handling. 4283 4284 void os::Linux::install_signal_handlers() { 4285 if (!signal_handlers_are_installed) { 4286 signal_handlers_are_installed = true; 4287 4288 // signal-chaining 4289 typedef void (*signal_setting_t)(); 4290 signal_setting_t begin_signal_setting = NULL; 4291 signal_setting_t end_signal_setting = NULL; 4292 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4293 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4294 if (begin_signal_setting != NULL) { 4295 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4296 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4297 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4298 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4299 libjsig_is_loaded = true; 4300 assert(UseSignalChaining, "should enable signal-chaining"); 4301 } 4302 if (libjsig_is_loaded) { 4303 // Tell libjsig jvm is setting signal handlers 4304 (*begin_signal_setting)(); 4305 } 4306 4307 set_signal_handler(SIGSEGV, true); 4308 set_signal_handler(SIGPIPE, true); 4309 set_signal_handler(SIGBUS, true); 4310 set_signal_handler(SIGILL, true); 4311 set_signal_handler(SIGFPE, true); 4312 #if defined(PPC64) 4313 set_signal_handler(SIGTRAP, true); 4314 #endif 4315 set_signal_handler(SIGXFSZ, true); 4316 4317 if (libjsig_is_loaded) { 4318 // Tell libjsig jvm finishes setting signal handlers 4319 (*end_signal_setting)(); 4320 } 4321 4322 // We don't activate signal checker if libjsig is in place, we trust ourselves 4323 // and if UserSignalHandler is installed all bets are off. 4324 // Log that signal checking is off only if -verbose:jni is specified. 4325 if (CheckJNICalls) { 4326 if (libjsig_is_loaded) { 4327 if (PrintJNIResolving) { 4328 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4329 } 4330 check_signals = false; 4331 } 4332 if (AllowUserSignalHandlers) { 4333 if (PrintJNIResolving) { 4334 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4335 } 4336 check_signals = false; 4337 } 4338 } 4339 } 4340 } 4341 4342 // This is the fastest way to get thread cpu time on Linux. 4343 // Returns cpu time (user+sys) for any thread, not only for current. 4344 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4345 // It might work on 2.6.10+ with a special kernel/glibc patch. 4346 // For reference, please, see IEEE Std 1003.1-2004: 4347 // http://www.unix.org/single_unix_specification 4348 4349 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4350 struct timespec tp; 4351 int rc = os::Linux::clock_gettime(clockid, &tp); 4352 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4353 4354 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4355 } 4356 4357 ///// 4358 // glibc on Linux platform uses non-documented flag 4359 // to indicate, that some special sort of signal 4360 // trampoline is used. 4361 // We will never set this flag, and we should 4362 // ignore this flag in our diagnostic 4363 #ifdef SIGNIFICANT_SIGNAL_MASK 4364 #undef SIGNIFICANT_SIGNAL_MASK 4365 #endif 4366 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4367 4368 static const char* get_signal_handler_name(address handler, 4369 char* buf, int buflen) { 4370 int offset; 4371 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4372 if (found) { 4373 // skip directory names 4374 const char *p1, *p2; 4375 p1 = buf; 4376 size_t len = strlen(os::file_separator()); 4377 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4378 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4379 } else { 4380 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4381 } 4382 return buf; 4383 } 4384 4385 static void print_signal_handler(outputStream* st, int sig, 4386 char* buf, size_t buflen) { 4387 struct sigaction sa; 4388 4389 sigaction(sig, NULL, &sa); 4390 4391 // See comment for SIGNIFICANT_SIGNAL_MASK define 4392 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4393 4394 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4395 4396 address handler = (sa.sa_flags & SA_SIGINFO) 4397 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4398 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4399 4400 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4401 st->print("SIG_DFL"); 4402 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4403 st->print("SIG_IGN"); 4404 } else { 4405 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4406 } 4407 4408 st->print(", sa_mask[0]="); 4409 os::Posix::print_signal_set_short(st, &sa.sa_mask); 4410 4411 address rh = VMError::get_resetted_sighandler(sig); 4412 // May be, handler was resetted by VMError? 4413 if(rh != NULL) { 4414 handler = rh; 4415 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4416 } 4417 4418 st->print(", sa_flags="); 4419 os::Posix::print_sa_flags(st, sa.sa_flags); 4420 4421 // Check: is it our handler? 4422 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4423 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4424 // It is our signal handler 4425 // check for flags, reset system-used one! 4426 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4427 st->print( 4428 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4429 os::Linux::get_our_sigflags(sig)); 4430 } 4431 } 4432 st->cr(); 4433 } 4434 4435 4436 #define DO_SIGNAL_CHECK(sig) \ 4437 if (!sigismember(&check_signal_done, sig)) \ 4438 os::Linux::check_signal_handler(sig) 4439 4440 // This method is a periodic task to check for misbehaving JNI applications 4441 // under CheckJNI, we can add any periodic checks here 4442 4443 void os::run_periodic_checks() { 4444 4445 if (check_signals == false) return; 4446 4447 // SEGV and BUS if overridden could potentially prevent 4448 // generation of hs*.log in the event of a crash, debugging 4449 // such a case can be very challenging, so we absolutely 4450 // check the following for a good measure: 4451 DO_SIGNAL_CHECK(SIGSEGV); 4452 DO_SIGNAL_CHECK(SIGILL); 4453 DO_SIGNAL_CHECK(SIGFPE); 4454 DO_SIGNAL_CHECK(SIGBUS); 4455 DO_SIGNAL_CHECK(SIGPIPE); 4456 DO_SIGNAL_CHECK(SIGXFSZ); 4457 #if defined(PPC64) 4458 DO_SIGNAL_CHECK(SIGTRAP); 4459 #endif 4460 4461 // ReduceSignalUsage allows the user to override these handlers 4462 // see comments at the very top and jvm_solaris.h 4463 if (!ReduceSignalUsage) { 4464 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4465 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4466 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4467 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4468 } 4469 4470 DO_SIGNAL_CHECK(SR_signum); 4471 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4472 } 4473 4474 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4475 4476 static os_sigaction_t os_sigaction = NULL; 4477 4478 void os::Linux::check_signal_handler(int sig) { 4479 char buf[O_BUFLEN]; 4480 address jvmHandler = NULL; 4481 4482 4483 struct sigaction act; 4484 if (os_sigaction == NULL) { 4485 // only trust the default sigaction, in case it has been interposed 4486 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4487 if (os_sigaction == NULL) return; 4488 } 4489 4490 os_sigaction(sig, (struct sigaction*)NULL, &act); 4491 4492 4493 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4494 4495 address thisHandler = (act.sa_flags & SA_SIGINFO) 4496 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4497 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 4498 4499 4500 switch(sig) { 4501 case SIGSEGV: 4502 case SIGBUS: 4503 case SIGFPE: 4504 case SIGPIPE: 4505 case SIGILL: 4506 case SIGXFSZ: 4507 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4508 break; 4509 4510 case SHUTDOWN1_SIGNAL: 4511 case SHUTDOWN2_SIGNAL: 4512 case SHUTDOWN3_SIGNAL: 4513 case BREAK_SIGNAL: 4514 jvmHandler = (address)user_handler(); 4515 break; 4516 4517 case INTERRUPT_SIGNAL: 4518 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4519 break; 4520 4521 default: 4522 if (sig == SR_signum) { 4523 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4524 } else { 4525 return; 4526 } 4527 break; 4528 } 4529 4530 if (thisHandler != jvmHandler) { 4531 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4532 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4533 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4534 // No need to check this sig any longer 4535 sigaddset(&check_signal_done, sig); 4536 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4537 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4538 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4539 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4540 // No need to check this sig any longer 4541 sigaddset(&check_signal_done, sig); 4542 } 4543 4544 // Dump all the signal 4545 if (sigismember(&check_signal_done, sig)) { 4546 print_signal_handlers(tty, buf, O_BUFLEN); 4547 } 4548 } 4549 4550 extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 4551 4552 extern bool signal_name(int signo, char* buf, size_t len); 4553 4554 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4555 if (0 < exception_code && exception_code <= SIGRTMAX) { 4556 // signal 4557 if (!signal_name(exception_code, buf, size)) { 4558 jio_snprintf(buf, size, "SIG%d", exception_code); 4559 } 4560 return buf; 4561 } else { 4562 return NULL; 4563 } 4564 } 4565 4566 // this is called _before_ the most of global arguments have been parsed 4567 void os::init(void) { 4568 char dummy; /* used to get a guess on initial stack address */ 4569 // first_hrtime = gethrtime(); 4570 4571 // With LinuxThreads the JavaMain thread pid (primordial thread) 4572 // is different than the pid of the java launcher thread. 4573 // So, on Linux, the launcher thread pid is passed to the VM 4574 // via the sun.java.launcher.pid property. 4575 // Use this property instead of getpid() if it was correctly passed. 4576 // See bug 6351349. 4577 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4578 4579 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4580 4581 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4582 4583 init_random(1234567); 4584 4585 ThreadCritical::initialize(); 4586 4587 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4588 if (Linux::page_size() == -1) { 4589 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4590 strerror(errno))); 4591 } 4592 init_page_sizes((size_t) Linux::page_size()); 4593 4594 Linux::initialize_system_info(); 4595 4596 // main_thread points to the aboriginal thread 4597 Linux::_main_thread = pthread_self(); 4598 4599 Linux::clock_init(); 4600 initial_time_count = javaTimeNanos(); 4601 4602 // pthread_condattr initialization for monotonic clock 4603 int status; 4604 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4605 if ((status = pthread_condattr_init(_condattr)) != 0) { 4606 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4607 } 4608 // Only set the clock if CLOCK_MONOTONIC is available 4609 if (os::supports_monotonic_clock()) { 4610 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4611 if (status == EINVAL) { 4612 warning("Unable to use monotonic clock with relative timed-waits" \ 4613 " - changes to the time-of-day clock may have adverse affects"); 4614 } else { 4615 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4616 } 4617 } 4618 } 4619 // else it defaults to CLOCK_REALTIME 4620 4621 pthread_mutex_init(&dl_mutex, NULL); 4622 4623 // If the pagesize of the VM is greater than 8K determine the appropriate 4624 // number of initial guard pages. The user can change this with the 4625 // command line arguments, if needed. 4626 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4627 StackYellowPages = 1; 4628 StackRedPages = 1; 4629 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4630 } 4631 } 4632 4633 // To install functions for atexit system call 4634 extern "C" { 4635 static void perfMemory_exit_helper() { 4636 perfMemory_exit(); 4637 } 4638 } 4639 4640 // this is called _after_ the global arguments have been parsed 4641 jint os::init_2(void) 4642 { 4643 Linux::fast_thread_clock_init(); 4644 4645 // Allocate a single page and mark it as readable for safepoint polling 4646 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4647 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 4648 4649 os::set_polling_page( polling_page ); 4650 4651 #ifndef PRODUCT 4652 if(Verbose && PrintMiscellaneous) 4653 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 4654 #endif 4655 4656 if (!UseMembar) { 4657 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4658 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4659 os::set_memory_serialize_page( mem_serialize_page ); 4660 4661 #ifndef PRODUCT 4662 if(Verbose && PrintMiscellaneous) 4663 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 4664 #endif 4665 } 4666 4667 // initialize suspend/resume support - must do this before signal_sets_init() 4668 if (SR_initialize() != 0) { 4669 perror("SR_initialize failed"); 4670 return JNI_ERR; 4671 } 4672 4673 Linux::signal_sets_init(); 4674 Linux::install_signal_handlers(); 4675 4676 // Check minimum allowable stack size for thread creation and to initialize 4677 // the java system classes, including StackOverflowError - depends on page 4678 // size. Add a page for compiler2 recursion in main thread. 4679 // Add in 2*BytesPerWord times page size to account for VM stack during 4680 // class initialization depending on 32 or 64 bit VM. 4681 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4682 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4683 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4684 4685 size_t threadStackSizeInBytes = ThreadStackSize * K; 4686 if (threadStackSizeInBytes != 0 && 4687 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4688 tty->print_cr("\nThe stack size specified is too small, " 4689 "Specify at least %dk", 4690 os::Linux::min_stack_allowed/ K); 4691 return JNI_ERR; 4692 } 4693 4694 // Make the stack size a multiple of the page size so that 4695 // the yellow/red zones can be guarded. 4696 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4697 vm_page_size())); 4698 4699 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4700 4701 #if defined(IA32) 4702 workaround_expand_exec_shield_cs_limit(); 4703 #endif 4704 4705 Linux::libpthread_init(); 4706 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4707 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4708 Linux::glibc_version(), Linux::libpthread_version(), 4709 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4710 } 4711 4712 if (UseNUMA) { 4713 if (!Linux::libnuma_init()) { 4714 UseNUMA = false; 4715 } else { 4716 if ((Linux::numa_max_node() < 1)) { 4717 // There's only one node(they start from 0), disable NUMA. 4718 UseNUMA = false; 4719 } 4720 } 4721 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4722 // we can make the adaptive lgrp chunk resizing work. If the user specified 4723 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4724 // disable adaptive resizing. 4725 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4726 if (FLAG_IS_DEFAULT(UseNUMA)) { 4727 UseNUMA = false; 4728 } else { 4729 if (FLAG_IS_DEFAULT(UseLargePages) && 4730 FLAG_IS_DEFAULT(UseSHM) && 4731 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4732 UseLargePages = false; 4733 } else { 4734 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4735 UseAdaptiveSizePolicy = false; 4736 UseAdaptiveNUMAChunkSizing = false; 4737 } 4738 } 4739 } 4740 if (!UseNUMA && ForceNUMA) { 4741 UseNUMA = true; 4742 } 4743 } 4744 4745 if (MaxFDLimit) { 4746 // set the number of file descriptors to max. print out error 4747 // if getrlimit/setrlimit fails but continue regardless. 4748 struct rlimit nbr_files; 4749 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4750 if (status != 0) { 4751 if (PrintMiscellaneous && (Verbose || WizardMode)) 4752 perror("os::init_2 getrlimit failed"); 4753 } else { 4754 nbr_files.rlim_cur = nbr_files.rlim_max; 4755 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4756 if (status != 0) { 4757 if (PrintMiscellaneous && (Verbose || WizardMode)) 4758 perror("os::init_2 setrlimit failed"); 4759 } 4760 } 4761 } 4762 4763 // Initialize lock used to serialize thread creation (see os::create_thread) 4764 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4765 4766 // at-exit methods are called in the reverse order of their registration. 4767 // atexit functions are called on return from main or as a result of a 4768 // call to exit(3C). There can be only 32 of these functions registered 4769 // and atexit() does not set errno. 4770 4771 if (PerfAllowAtExitRegistration) { 4772 // only register atexit functions if PerfAllowAtExitRegistration is set. 4773 // atexit functions can be delayed until process exit time, which 4774 // can be problematic for embedded VM situations. Embedded VMs should 4775 // call DestroyJavaVM() to assure that VM resources are released. 4776 4777 // note: perfMemory_exit_helper atexit function may be removed in 4778 // the future if the appropriate cleanup code can be added to the 4779 // VM_Exit VMOperation's doit method. 4780 if (atexit(perfMemory_exit_helper) != 0) { 4781 warning("os::init_2 atexit(perfMemory_exit_helper) failed"); 4782 } 4783 } 4784 4785 // initialize thread priority policy 4786 prio_init(); 4787 4788 return JNI_OK; 4789 } 4790 4791 // this is called at the end of vm_initialization 4792 void os::init_3(void) { 4793 #ifdef JAVASE_EMBEDDED 4794 // Start the MemNotifyThread 4795 if (LowMemoryProtection) { 4796 MemNotifyThread::start(); 4797 } 4798 return; 4799 #endif 4800 } 4801 4802 // Mark the polling page as unreadable 4803 void os::make_polling_page_unreadable(void) { 4804 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 4805 fatal("Could not disable polling page"); 4806 }; 4807 4808 // Mark the polling page as readable 4809 void os::make_polling_page_readable(void) { 4810 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4811 fatal("Could not enable polling page"); 4812 } 4813 }; 4814 4815 int os::active_processor_count() { 4816 // Linux doesn't yet have a (official) notion of processor sets, 4817 // so just return the number of online processors. 4818 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4819 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4820 return online_cpus; 4821 } 4822 4823 void os::set_native_thread_name(const char *name) { 4824 // Not yet implemented. 4825 return; 4826 } 4827 4828 bool os::distribute_processes(uint length, uint* distribution) { 4829 // Not yet implemented. 4830 return false; 4831 } 4832 4833 bool os::bind_to_processor(uint processor_id) { 4834 // Not yet implemented. 4835 return false; 4836 } 4837 4838 /// 4839 4840 void os::SuspendedThreadTask::internal_do_task() { 4841 if (do_suspend(_thread->osthread())) { 4842 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4843 do_task(context); 4844 do_resume(_thread->osthread()); 4845 } 4846 } 4847 4848 class PcFetcher : public os::SuspendedThreadTask { 4849 public: 4850 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4851 ExtendedPC result(); 4852 protected: 4853 void do_task(const os::SuspendedThreadTaskContext& context); 4854 private: 4855 ExtendedPC _epc; 4856 }; 4857 4858 ExtendedPC PcFetcher::result() { 4859 guarantee(is_done(), "task is not done yet."); 4860 return _epc; 4861 } 4862 4863 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 4864 Thread* thread = context.thread(); 4865 OSThread* osthread = thread->osthread(); 4866 if (osthread->ucontext() != NULL) { 4867 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 4868 } else { 4869 // NULL context is unexpected, double-check this is the VMThread 4870 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4871 } 4872 } 4873 4874 // Suspends the target using the signal mechanism and then grabs the PC before 4875 // resuming the target. Used by the flat-profiler only 4876 ExtendedPC os::get_thread_pc(Thread* thread) { 4877 // Make sure that it is called by the watcher for the VMThread 4878 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4879 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4880 4881 PcFetcher fetcher(thread); 4882 fetcher.run(); 4883 return fetcher.result(); 4884 } 4885 4886 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 4887 { 4888 if (is_NPTL()) { 4889 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4890 } else { 4891 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4892 // word back to default 64bit precision if condvar is signaled. Java 4893 // wants 53bit precision. Save and restore current value. 4894 int fpu = get_fpu_control_word(); 4895 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4896 set_fpu_control_word(fpu); 4897 return status; 4898 } 4899 } 4900 4901 //////////////////////////////////////////////////////////////////////////////// 4902 // debug support 4903 4904 bool os::find(address addr, outputStream* st) { 4905 Dl_info dlinfo; 4906 memset(&dlinfo, 0, sizeof(dlinfo)); 4907 if (dladdr(addr, &dlinfo) != 0) { 4908 st->print(PTR_FORMAT ": ", addr); 4909 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 4910 st->print("%s+%#x", dlinfo.dli_sname, 4911 addr - (intptr_t)dlinfo.dli_saddr); 4912 } else if (dlinfo.dli_fbase != NULL) { 4913 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4914 } else { 4915 st->print("<absolute address>"); 4916 } 4917 if (dlinfo.dli_fname != NULL) { 4918 st->print(" in %s", dlinfo.dli_fname); 4919 } 4920 if (dlinfo.dli_fbase != NULL) { 4921 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4922 } 4923 st->cr(); 4924 4925 if (Verbose) { 4926 // decode some bytes around the PC 4927 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 4928 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 4929 address lowest = (address) dlinfo.dli_sname; 4930 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4931 if (begin < lowest) begin = lowest; 4932 Dl_info dlinfo2; 4933 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 4934 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 4935 end = (address) dlinfo2.dli_saddr; 4936 Disassembler::decode(begin, end, st); 4937 } 4938 return true; 4939 } 4940 return false; 4941 } 4942 4943 //////////////////////////////////////////////////////////////////////////////// 4944 // misc 4945 4946 // This does not do anything on Linux. This is basically a hook for being 4947 // able to use structured exception handling (thread-local exception filters) 4948 // on, e.g., Win32. 4949 void 4950 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 4951 JavaCallArguments* args, Thread* thread) { 4952 f(value, method, args, thread); 4953 } 4954 4955 void os::print_statistics() { 4956 } 4957 4958 int os::message_box(const char* title, const char* message) { 4959 int i; 4960 fdStream err(defaultStream::error_fd()); 4961 for (i = 0; i < 78; i++) err.print_raw("="); 4962 err.cr(); 4963 err.print_raw_cr(title); 4964 for (i = 0; i < 78; i++) err.print_raw("-"); 4965 err.cr(); 4966 err.print_raw_cr(message); 4967 for (i = 0; i < 78; i++) err.print_raw("="); 4968 err.cr(); 4969 4970 char buf[16]; 4971 // Prevent process from exiting upon "read error" without consuming all CPU 4972 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 4973 4974 return buf[0] == 'y' || buf[0] == 'Y'; 4975 } 4976 4977 int os::stat(const char *path, struct stat *sbuf) { 4978 char pathbuf[MAX_PATH]; 4979 if (strlen(path) > MAX_PATH - 1) { 4980 errno = ENAMETOOLONG; 4981 return -1; 4982 } 4983 os::native_path(strcpy(pathbuf, path)); 4984 return ::stat(pathbuf, sbuf); 4985 } 4986 4987 bool os::check_heap(bool force) { 4988 return true; 4989 } 4990 4991 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 4992 return ::vsnprintf(buf, count, format, args); 4993 } 4994 4995 // Is a (classpath) directory empty? 4996 bool os::dir_is_empty(const char* path) { 4997 DIR *dir = NULL; 4998 struct dirent *ptr; 4999 5000 dir = opendir(path); 5001 if (dir == NULL) return true; 5002 5003 /* Scan the directory */ 5004 bool result = true; 5005 char buf[sizeof(struct dirent) + MAX_PATH]; 5006 while (result && (ptr = ::readdir(dir)) != NULL) { 5007 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5008 result = false; 5009 } 5010 } 5011 closedir(dir); 5012 return result; 5013 } 5014 5015 // This code originates from JDK's sysOpen and open64_w 5016 // from src/solaris/hpi/src/system_md.c 5017 5018 #ifndef O_DELETE 5019 #define O_DELETE 0x10000 5020 #endif 5021 5022 // Open a file. Unlink the file immediately after open returns 5023 // if the specified oflag has the O_DELETE flag set. 5024 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c 5025 5026 int os::open(const char *path, int oflag, int mode) { 5027 5028 if (strlen(path) > MAX_PATH - 1) { 5029 errno = ENAMETOOLONG; 5030 return -1; 5031 } 5032 int fd; 5033 int o_delete = (oflag & O_DELETE); 5034 oflag = oflag & ~O_DELETE; 5035 5036 fd = ::open64(path, oflag, mode); 5037 if (fd == -1) return -1; 5038 5039 //If the open succeeded, the file might still be a directory 5040 { 5041 struct stat64 buf64; 5042 int ret = ::fstat64(fd, &buf64); 5043 int st_mode = buf64.st_mode; 5044 5045 if (ret != -1) { 5046 if ((st_mode & S_IFMT) == S_IFDIR) { 5047 errno = EISDIR; 5048 ::close(fd); 5049 return -1; 5050 } 5051 } else { 5052 ::close(fd); 5053 return -1; 5054 } 5055 } 5056 5057 /* 5058 * All file descriptors that are opened in the JVM and not 5059 * specifically destined for a subprocess should have the 5060 * close-on-exec flag set. If we don't set it, then careless 3rd 5061 * party native code might fork and exec without closing all 5062 * appropriate file descriptors (e.g. as we do in closeDescriptors in 5063 * UNIXProcess.c), and this in turn might: 5064 * 5065 * - cause end-of-file to fail to be detected on some file 5066 * descriptors, resulting in mysterious hangs, or 5067 * 5068 * - might cause an fopen in the subprocess to fail on a system 5069 * suffering from bug 1085341. 5070 * 5071 * (Yes, the default setting of the close-on-exec flag is a Unix 5072 * design flaw) 5073 * 5074 * See: 5075 * 1085341: 32-bit stdio routines should support file descriptors >255 5076 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5077 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5078 */ 5079 #ifdef FD_CLOEXEC 5080 { 5081 int flags = ::fcntl(fd, F_GETFD); 5082 if (flags != -1) 5083 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5084 } 5085 #endif 5086 5087 if (o_delete != 0) { 5088 ::unlink(path); 5089 } 5090 return fd; 5091 } 5092 5093 5094 // create binary file, rewriting existing file if required 5095 int os::create_binary_file(const char* path, bool rewrite_existing) { 5096 int oflags = O_WRONLY | O_CREAT; 5097 if (!rewrite_existing) { 5098 oflags |= O_EXCL; 5099 } 5100 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5101 } 5102 5103 // return current position of file pointer 5104 jlong os::current_file_offset(int fd) { 5105 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5106 } 5107 5108 // move file pointer to the specified offset 5109 jlong os::seek_to_file_offset(int fd, jlong offset) { 5110 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5111 } 5112 5113 // This code originates from JDK's sysAvailable 5114 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5115 5116 int os::available(int fd, jlong *bytes) { 5117 jlong cur, end; 5118 int mode; 5119 struct stat64 buf64; 5120 5121 if (::fstat64(fd, &buf64) >= 0) { 5122 mode = buf64.st_mode; 5123 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5124 /* 5125 * XXX: is the following call interruptible? If so, this might 5126 * need to go through the INTERRUPT_IO() wrapper as for other 5127 * blocking, interruptible calls in this file. 5128 */ 5129 int n; 5130 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5131 *bytes = n; 5132 return 1; 5133 } 5134 } 5135 } 5136 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5137 return 0; 5138 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5139 return 0; 5140 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5141 return 0; 5142 } 5143 *bytes = end - cur; 5144 return 1; 5145 } 5146 5147 int os::socket_available(int fd, jint *pbytes) { 5148 // Linux doc says EINTR not returned, unlike Solaris 5149 int ret = ::ioctl(fd, FIONREAD, pbytes); 5150 5151 //%% note ioctl can return 0 when successful, JVM_SocketAvailable 5152 // is expected to return 0 on failure and 1 on success to the jdk. 5153 return (ret < 0) ? 0 : 1; 5154 } 5155 5156 // Map a block of memory. 5157 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5158 char *addr, size_t bytes, bool read_only, 5159 bool allow_exec) { 5160 int prot; 5161 int flags = MAP_PRIVATE; 5162 5163 if (read_only) { 5164 prot = PROT_READ; 5165 } else { 5166 prot = PROT_READ | PROT_WRITE; 5167 } 5168 5169 if (allow_exec) { 5170 prot |= PROT_EXEC; 5171 } 5172 5173 if (addr != NULL) { 5174 flags |= MAP_FIXED; 5175 } 5176 5177 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5178 fd, file_offset); 5179 if (mapped_address == MAP_FAILED) { 5180 return NULL; 5181 } 5182 return mapped_address; 5183 } 5184 5185 5186 // Remap a block of memory. 5187 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5188 char *addr, size_t bytes, bool read_only, 5189 bool allow_exec) { 5190 // same as map_memory() on this OS 5191 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5192 allow_exec); 5193 } 5194 5195 5196 // Unmap a block of memory. 5197 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5198 return munmap(addr, bytes) == 0; 5199 } 5200 5201 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5202 5203 static clockid_t thread_cpu_clockid(Thread* thread) { 5204 pthread_t tid = thread->osthread()->pthread_id(); 5205 clockid_t clockid; 5206 5207 // Get thread clockid 5208 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5209 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5210 return clockid; 5211 } 5212 5213 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5214 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5215 // of a thread. 5216 // 5217 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5218 // the fast estimate available on the platform. 5219 5220 jlong os::current_thread_cpu_time() { 5221 if (os::Linux::supports_fast_thread_cpu_time()) { 5222 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5223 } else { 5224 // return user + sys since the cost is the same 5225 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5226 } 5227 } 5228 5229 jlong os::thread_cpu_time(Thread* thread) { 5230 // consistent with what current_thread_cpu_time() returns 5231 if (os::Linux::supports_fast_thread_cpu_time()) { 5232 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5233 } else { 5234 return slow_thread_cpu_time(thread, true /* user + sys */); 5235 } 5236 } 5237 5238 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5239 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5240 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5241 } else { 5242 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5243 } 5244 } 5245 5246 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5247 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5248 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5249 } else { 5250 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5251 } 5252 } 5253 5254 // 5255 // -1 on error. 5256 // 5257 5258 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5259 static bool proc_task_unchecked = true; 5260 pid_t tid = thread->osthread()->thread_id(); 5261 char *s; 5262 char stat[2048]; 5263 int statlen; 5264 char proc_name[64]; 5265 int count; 5266 long sys_time, user_time; 5267 char cdummy; 5268 int idummy; 5269 long ldummy; 5270 FILE *fp; 5271 5272 snprintf(proc_name, 64, "/proc/%d/stat", tid); 5273 5274 // The /proc/<tid>/stat aggregates per-process usage on 5275 // new Linux kernels 2.6+ where NPTL is supported. 5276 // The /proc/self/task/<tid>/stat still has the per-thread usage. 5277 // See bug 6328462. 5278 // There possibly can be cases where there is no directory 5279 // /proc/self/task, so we check its availability. 5280 if (proc_task_unchecked && os::Linux::is_NPTL()) { 5281 // This is executed only once 5282 proc_task_unchecked = false; 5283 fp = fopen("/proc/self/task", "r"); 5284 if (fp != NULL) { 5285 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid); 5286 fclose(fp); 5287 } 5288 } 5289 5290 fp = fopen(proc_name, "r"); 5291 if ( fp == NULL ) return -1; 5292 statlen = fread(stat, 1, 2047, fp); 5293 stat[statlen] = '\0'; 5294 fclose(fp); 5295 5296 // Skip pid and the command string. Note that we could be dealing with 5297 // weird command names, e.g. user could decide to rename java launcher 5298 // to "java 1.4.2 :)", then the stat file would look like 5299 // 1234 (java 1.4.2 :)) R ... ... 5300 // We don't really need to know the command string, just find the last 5301 // occurrence of ")" and then start parsing from there. See bug 4726580. 5302 s = strrchr(stat, ')'); 5303 if (s == NULL ) return -1; 5304 5305 // Skip blank chars 5306 do s++; while (isspace(*s)); 5307 5308 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5309 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5310 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5311 &user_time, &sys_time); 5312 if ( count != 13 ) return -1; 5313 if (user_sys_cpu_time) { 5314 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5315 } else { 5316 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5317 } 5318 } 5319 5320 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5321 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5322 info_ptr->may_skip_backward = false; // elapsed time not wall time 5323 info_ptr->may_skip_forward = false; // elapsed time not wall time 5324 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5325 } 5326 5327 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5328 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5329 info_ptr->may_skip_backward = false; // elapsed time not wall time 5330 info_ptr->may_skip_forward = false; // elapsed time not wall time 5331 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5332 } 5333 5334 bool os::is_thread_cpu_time_supported() { 5335 return true; 5336 } 5337 5338 // System loadavg support. Returns -1 if load average cannot be obtained. 5339 // Linux doesn't yet have a (official) notion of processor sets, 5340 // so just return the system wide load average. 5341 int os::loadavg(double loadavg[], int nelem) { 5342 return ::getloadavg(loadavg, nelem); 5343 } 5344 5345 void os::pause() { 5346 char filename[MAX_PATH]; 5347 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5348 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5349 } else { 5350 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5351 } 5352 5353 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5354 if (fd != -1) { 5355 struct stat buf; 5356 ::close(fd); 5357 while (::stat(filename, &buf) == 0) { 5358 (void)::poll(NULL, 0, 100); 5359 } 5360 } else { 5361 jio_fprintf(stderr, 5362 "Could not open pause file '%s', continuing immediately.\n", filename); 5363 } 5364 } 5365 5366 5367 // Refer to the comments in os_solaris.cpp park-unpark. 5368 // 5369 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5370 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5371 // For specifics regarding the bug see GLIBC BUGID 261237 : 5372 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5373 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5374 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5375 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5376 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5377 // and monitorenter when we're using 1-0 locking. All those operations may result in 5378 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5379 // of libpthread avoids the problem, but isn't practical. 5380 // 5381 // Possible remedies: 5382 // 5383 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5384 // This is palliative and probabilistic, however. If the thread is preempted 5385 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5386 // than the minimum period may have passed, and the abstime may be stale (in the 5387 // past) resultin in a hang. Using this technique reduces the odds of a hang 5388 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5389 // 5390 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5391 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5392 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5393 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5394 // thread. 5395 // 5396 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5397 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5398 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5399 // This also works well. In fact it avoids kernel-level scalability impediments 5400 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5401 // timers in a graceful fashion. 5402 // 5403 // 4. When the abstime value is in the past it appears that control returns 5404 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5405 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5406 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5407 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5408 // It may be possible to avoid reinitialization by checking the return 5409 // value from pthread_cond_timedwait(). In addition to reinitializing the 5410 // condvar we must establish the invariant that cond_signal() is only called 5411 // within critical sections protected by the adjunct mutex. This prevents 5412 // cond_signal() from "seeing" a condvar that's in the midst of being 5413 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5414 // desirable signal-after-unlock optimization that avoids futile context switching. 5415 // 5416 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5417 // structure when a condvar is used or initialized. cond_destroy() would 5418 // release the helper structure. Our reinitialize-after-timedwait fix 5419 // put excessive stress on malloc/free and locks protecting the c-heap. 5420 // 5421 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5422 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5423 // and only enabling the work-around for vulnerable environments. 5424 5425 // utility to compute the abstime argument to timedwait: 5426 // millis is the relative timeout time 5427 // abstime will be the absolute timeout time 5428 // TODO: replace compute_abstime() with unpackTime() 5429 5430 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5431 if (millis < 0) millis = 0; 5432 5433 jlong seconds = millis / 1000; 5434 millis %= 1000; 5435 if (seconds > 50000000) { // see man cond_timedwait(3T) 5436 seconds = 50000000; 5437 } 5438 5439 if (os::supports_monotonic_clock()) { 5440 struct timespec now; 5441 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5442 assert_status(status == 0, status, "clock_gettime"); 5443 abstime->tv_sec = now.tv_sec + seconds; 5444 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5445 if (nanos >= NANOSECS_PER_SEC) { 5446 abstime->tv_sec += 1; 5447 nanos -= NANOSECS_PER_SEC; 5448 } 5449 abstime->tv_nsec = nanos; 5450 } else { 5451 struct timeval now; 5452 int status = gettimeofday(&now, NULL); 5453 assert(status == 0, "gettimeofday"); 5454 abstime->tv_sec = now.tv_sec + seconds; 5455 long usec = now.tv_usec + millis * 1000; 5456 if (usec >= 1000000) { 5457 abstime->tv_sec += 1; 5458 usec -= 1000000; 5459 } 5460 abstime->tv_nsec = usec * 1000; 5461 } 5462 return abstime; 5463 } 5464 5465 5466 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 5467 // Conceptually TryPark() should be equivalent to park(0). 5468 5469 int os::PlatformEvent::TryPark() { 5470 for (;;) { 5471 const int v = _Event ; 5472 guarantee ((v == 0) || (v == 1), "invariant") ; 5473 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 5474 } 5475 } 5476 5477 void os::PlatformEvent::park() { // AKA "down()" 5478 // Invariant: Only the thread associated with the Event/PlatformEvent 5479 // may call park(). 5480 // TODO: assert that _Assoc != NULL or _Assoc == Self 5481 int v ; 5482 for (;;) { 5483 v = _Event ; 5484 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5485 } 5486 guarantee (v >= 0, "invariant") ; 5487 if (v == 0) { 5488 // Do this the hard way by blocking ... 5489 int status = pthread_mutex_lock(_mutex); 5490 assert_status(status == 0, status, "mutex_lock"); 5491 guarantee (_nParked == 0, "invariant") ; 5492 ++ _nParked ; 5493 while (_Event < 0) { 5494 status = pthread_cond_wait(_cond, _mutex); 5495 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5496 // Treat this the same as if the wait was interrupted 5497 if (status == ETIME) { status = EINTR; } 5498 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5499 } 5500 -- _nParked ; 5501 5502 _Event = 0 ; 5503 status = pthread_mutex_unlock(_mutex); 5504 assert_status(status == 0, status, "mutex_unlock"); 5505 // Paranoia to ensure our locked and lock-free paths interact 5506 // correctly with each other. 5507 OrderAccess::fence(); 5508 } 5509 guarantee (_Event >= 0, "invariant") ; 5510 } 5511 5512 int os::PlatformEvent::park(jlong millis) { 5513 guarantee (_nParked == 0, "invariant") ; 5514 5515 int v ; 5516 for (;;) { 5517 v = _Event ; 5518 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5519 } 5520 guarantee (v >= 0, "invariant") ; 5521 if (v != 0) return OS_OK ; 5522 5523 // We do this the hard way, by blocking the thread. 5524 // Consider enforcing a minimum timeout value. 5525 struct timespec abst; 5526 compute_abstime(&abst, millis); 5527 5528 int ret = OS_TIMEOUT; 5529 int status = pthread_mutex_lock(_mutex); 5530 assert_status(status == 0, status, "mutex_lock"); 5531 guarantee (_nParked == 0, "invariant") ; 5532 ++_nParked ; 5533 5534 // Object.wait(timo) will return because of 5535 // (a) notification 5536 // (b) timeout 5537 // (c) thread.interrupt 5538 // 5539 // Thread.interrupt and object.notify{All} both call Event::set. 5540 // That is, we treat thread.interrupt as a special case of notification. 5541 // The underlying Solaris implementation, cond_timedwait, admits 5542 // spurious/premature wakeups, but the JLS/JVM spec prevents the 5543 // JVM from making those visible to Java code. As such, we must 5544 // filter out spurious wakeups. We assume all ETIME returns are valid. 5545 // 5546 // TODO: properly differentiate simultaneous notify+interrupt. 5547 // In that case, we should propagate the notify to another waiter. 5548 5549 while (_Event < 0) { 5550 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5551 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5552 pthread_cond_destroy (_cond); 5553 pthread_cond_init (_cond, os::Linux::condAttr()) ; 5554 } 5555 assert_status(status == 0 || status == EINTR || 5556 status == ETIME || status == ETIMEDOUT, 5557 status, "cond_timedwait"); 5558 if (!FilterSpuriousWakeups) break ; // previous semantics 5559 if (status == ETIME || status == ETIMEDOUT) break ; 5560 // We consume and ignore EINTR and spurious wakeups. 5561 } 5562 --_nParked ; 5563 if (_Event >= 0) { 5564 ret = OS_OK; 5565 } 5566 _Event = 0 ; 5567 status = pthread_mutex_unlock(_mutex); 5568 assert_status(status == 0, status, "mutex_unlock"); 5569 assert (_nParked == 0, "invariant") ; 5570 // Paranoia to ensure our locked and lock-free paths interact 5571 // correctly with each other. 5572 OrderAccess::fence(); 5573 return ret; 5574 } 5575 5576 void os::PlatformEvent::unpark() { 5577 // Transitions for _Event: 5578 // 0 :=> 1 5579 // 1 :=> 1 5580 // -1 :=> either 0 or 1; must signal target thread 5581 // That is, we can safely transition _Event from -1 to either 5582 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back 5583 // unpark() calls. 5584 // See also: "Semaphores in Plan 9" by Mullender & Cox 5585 // 5586 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5587 // that it will take two back-to-back park() calls for the owning 5588 // thread to block. This has the benefit of forcing a spurious return 5589 // from the first park() call after an unpark() call which will help 5590 // shake out uses of park() and unpark() without condition variables. 5591 5592 if (Atomic::xchg(1, &_Event) >= 0) return; 5593 5594 // Wait for the thread associated with the event to vacate 5595 int status = pthread_mutex_lock(_mutex); 5596 assert_status(status == 0, status, "mutex_lock"); 5597 int AnyWaiters = _nParked; 5598 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5599 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5600 AnyWaiters = 0; 5601 pthread_cond_signal(_cond); 5602 } 5603 status = pthread_mutex_unlock(_mutex); 5604 assert_status(status == 0, status, "mutex_unlock"); 5605 if (AnyWaiters != 0) { 5606 status = pthread_cond_signal(_cond); 5607 assert_status(status == 0, status, "cond_signal"); 5608 } 5609 5610 // Note that we signal() _after dropping the lock for "immortal" Events. 5611 // This is safe and avoids a common class of futile wakeups. In rare 5612 // circumstances this can cause a thread to return prematurely from 5613 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 5614 // simply re-test the condition and re-park itself. 5615 } 5616 5617 5618 // JSR166 5619 // ------------------------------------------------------- 5620 5621 /* 5622 * The solaris and linux implementations of park/unpark are fairly 5623 * conservative for now, but can be improved. They currently use a 5624 * mutex/condvar pair, plus a a count. 5625 * Park decrements count if > 0, else does a condvar wait. Unpark 5626 * sets count to 1 and signals condvar. Only one thread ever waits 5627 * on the condvar. Contention seen when trying to park implies that someone 5628 * is unparking you, so don't wait. And spurious returns are fine, so there 5629 * is no need to track notifications. 5630 */ 5631 5632 #define MAX_SECS 100000000 5633 /* 5634 * This code is common to linux and solaris and will be moved to a 5635 * common place in dolphin. 5636 * 5637 * The passed in time value is either a relative time in nanoseconds 5638 * or an absolute time in milliseconds. Either way it has to be unpacked 5639 * into suitable seconds and nanoseconds components and stored in the 5640 * given timespec structure. 5641 * Given time is a 64-bit value and the time_t used in the timespec is only 5642 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 5643 * overflow if times way in the future are given. Further on Solaris versions 5644 * prior to 10 there is a restriction (see cond_timedwait) that the specified 5645 * number of seconds, in abstime, is less than current_time + 100,000,000. 5646 * As it will be 28 years before "now + 100000000" will overflow we can 5647 * ignore overflow and just impose a hard-limit on seconds using the value 5648 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 5649 * years from "now". 5650 */ 5651 5652 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5653 assert (time > 0, "convertTime"); 5654 time_t max_secs = 0; 5655 5656 if (!os::supports_monotonic_clock() || isAbsolute) { 5657 struct timeval now; 5658 int status = gettimeofday(&now, NULL); 5659 assert(status == 0, "gettimeofday"); 5660 5661 max_secs = now.tv_sec + MAX_SECS; 5662 5663 if (isAbsolute) { 5664 jlong secs = time / 1000; 5665 if (secs > max_secs) { 5666 absTime->tv_sec = max_secs; 5667 } else { 5668 absTime->tv_sec = secs; 5669 } 5670 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5671 } else { 5672 jlong secs = time / NANOSECS_PER_SEC; 5673 if (secs >= MAX_SECS) { 5674 absTime->tv_sec = max_secs; 5675 absTime->tv_nsec = 0; 5676 } else { 5677 absTime->tv_sec = now.tv_sec + secs; 5678 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5679 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5680 absTime->tv_nsec -= NANOSECS_PER_SEC; 5681 ++absTime->tv_sec; // note: this must be <= max_secs 5682 } 5683 } 5684 } 5685 } else { 5686 // must be relative using monotonic clock 5687 struct timespec now; 5688 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5689 assert_status(status == 0, status, "clock_gettime"); 5690 max_secs = now.tv_sec + MAX_SECS; 5691 jlong secs = time / NANOSECS_PER_SEC; 5692 if (secs >= MAX_SECS) { 5693 absTime->tv_sec = max_secs; 5694 absTime->tv_nsec = 0; 5695 } else { 5696 absTime->tv_sec = now.tv_sec + secs; 5697 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5698 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5699 absTime->tv_nsec -= NANOSECS_PER_SEC; 5700 ++absTime->tv_sec; // note: this must be <= max_secs 5701 } 5702 } 5703 } 5704 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5705 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5706 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5707 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5708 } 5709 5710 void Parker::park(bool isAbsolute, jlong time) { 5711 // Ideally we'd do something useful while spinning, such 5712 // as calling unpackTime(). 5713 5714 // Optional fast-path check: 5715 // Return immediately if a permit is available. 5716 // We depend on Atomic::xchg() having full barrier semantics 5717 // since we are doing a lock-free update to _counter. 5718 if (Atomic::xchg(0, &_counter) > 0) return; 5719 5720 Thread* thread = Thread::current(); 5721 assert(thread->is_Java_thread(), "Must be JavaThread"); 5722 JavaThread *jt = (JavaThread *)thread; 5723 5724 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5725 // Check interrupt before trying to wait 5726 if (Thread::is_interrupted(thread, false)) { 5727 return; 5728 } 5729 5730 // Next, demultiplex/decode time arguments 5731 timespec absTime; 5732 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all 5733 return; 5734 } 5735 if (time > 0) { 5736 unpackTime(&absTime, isAbsolute, time); 5737 } 5738 5739 5740 // Enter safepoint region 5741 // Beware of deadlocks such as 6317397. 5742 // The per-thread Parker:: mutex is a classic leaf-lock. 5743 // In particular a thread must never block on the Threads_lock while 5744 // holding the Parker:: mutex. If safepoints are pending both the 5745 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5746 ThreadBlockInVM tbivm(jt); 5747 5748 // Don't wait if cannot get lock since interference arises from 5749 // unblocking. Also. check interrupt before trying wait 5750 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5751 return; 5752 } 5753 5754 int status ; 5755 if (_counter > 0) { // no wait needed 5756 _counter = 0; 5757 status = pthread_mutex_unlock(_mutex); 5758 assert (status == 0, "invariant") ; 5759 // Paranoia to ensure our locked and lock-free paths interact 5760 // correctly with each other and Java-level accesses. 5761 OrderAccess::fence(); 5762 return; 5763 } 5764 5765 #ifdef ASSERT 5766 // Don't catch signals while blocked; let the running threads have the signals. 5767 // (This allows a debugger to break into the running thread.) 5768 sigset_t oldsigs; 5769 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5770 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5771 #endif 5772 5773 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5774 jt->set_suspend_equivalent(); 5775 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5776 5777 assert(_cur_index == -1, "invariant"); 5778 if (time == 0) { 5779 _cur_index = REL_INDEX; // arbitrary choice when not timed 5780 status = pthread_cond_wait (&_cond[_cur_index], _mutex) ; 5781 } else { 5782 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5783 status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ; 5784 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5785 pthread_cond_destroy (&_cond[_cur_index]) ; 5786 pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5787 } 5788 } 5789 _cur_index = -1; 5790 assert_status(status == 0 || status == EINTR || 5791 status == ETIME || status == ETIMEDOUT, 5792 status, "cond_timedwait"); 5793 5794 #ifdef ASSERT 5795 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5796 #endif 5797 5798 _counter = 0 ; 5799 status = pthread_mutex_unlock(_mutex) ; 5800 assert_status(status == 0, status, "invariant") ; 5801 // Paranoia to ensure our locked and lock-free paths interact 5802 // correctly with each other and Java-level accesses. 5803 OrderAccess::fence(); 5804 5805 // If externally suspended while waiting, re-suspend 5806 if (jt->handle_special_suspend_equivalent_condition()) { 5807 jt->java_suspend_self(); 5808 } 5809 } 5810 5811 void Parker::unpark() { 5812 int s, status ; 5813 status = pthread_mutex_lock(_mutex); 5814 assert (status == 0, "invariant") ; 5815 s = _counter; 5816 _counter = 1; 5817 if (s < 1) { 5818 // thread might be parked 5819 if (_cur_index != -1) { 5820 // thread is definitely parked 5821 if (WorkAroundNPTLTimedWaitHang) { 5822 status = pthread_cond_signal (&_cond[_cur_index]); 5823 assert (status == 0, "invariant"); 5824 status = pthread_mutex_unlock(_mutex); 5825 assert (status == 0, "invariant"); 5826 } else { 5827 status = pthread_mutex_unlock(_mutex); 5828 assert (status == 0, "invariant"); 5829 status = pthread_cond_signal (&_cond[_cur_index]); 5830 assert (status == 0, "invariant"); 5831 } 5832 } else { 5833 pthread_mutex_unlock(_mutex); 5834 assert (status == 0, "invariant") ; 5835 } 5836 } else { 5837 pthread_mutex_unlock(_mutex); 5838 assert (status == 0, "invariant") ; 5839 } 5840 } 5841 5842 5843 extern char** environ; 5844 5845 #ifndef __NR_fork 5846 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5847 #endif 5848 5849 #ifndef __NR_execve 5850 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 5851 #endif 5852 5853 // Run the specified command in a separate process. Return its exit value, 5854 // or -1 on failure (e.g. can't fork a new process). 5855 // Unlike system(), this function can be called from signal handler. It 5856 // doesn't block SIGINT et al. 5857 int os::fork_and_exec(char* cmd) { 5858 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5859 5860 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5861 // pthread_atfork handlers and reset pthread library. All we need is a 5862 // separate process to execve. Make a direct syscall to fork process. 5863 // On IA64 there's no fork syscall, we have to use fork() and hope for 5864 // the best... 5865 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5866 IA64_ONLY(fork();) 5867 5868 if (pid < 0) { 5869 // fork failed 5870 return -1; 5871 5872 } else if (pid == 0) { 5873 // child process 5874 5875 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5876 // first to kill every thread on the thread list. Because this list is 5877 // not reset by fork() (see notes above), execve() will instead kill 5878 // every thread in the parent process. We know this is the only thread 5879 // in the new process, so make a system call directly. 5880 // IA64 should use normal execve() from glibc to match the glibc fork() 5881 // above. 5882 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5883 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5884 5885 // execve failed 5886 _exit(-1); 5887 5888 } else { 5889 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5890 // care about the actual exit code, for now. 5891 5892 int status; 5893 5894 // Wait for the child process to exit. This returns immediately if 5895 // the child has already exited. */ 5896 while (waitpid(pid, &status, 0) < 0) { 5897 switch (errno) { 5898 case ECHILD: return 0; 5899 case EINTR: break; 5900 default: return -1; 5901 } 5902 } 5903 5904 if (WIFEXITED(status)) { 5905 // The child exited normally; get its exit code. 5906 return WEXITSTATUS(status); 5907 } else if (WIFSIGNALED(status)) { 5908 // The child exited because of a signal 5909 // The best value to return is 0x80 + signal number, 5910 // because that is what all Unix shells do, and because 5911 // it allows callers to distinguish between process exit and 5912 // process death by signal. 5913 return 0x80 + WTERMSIG(status); 5914 } else { 5915 // Unknown exit code; pass it through 5916 return status; 5917 } 5918 } 5919 } 5920 5921 // is_headless_jre() 5922 // 5923 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 5924 // in order to report if we are running in a headless jre 5925 // 5926 // Since JDK8 xawt/libmawt.so was moved into the same directory 5927 // as libawt.so, and renamed libawt_xawt.so 5928 // 5929 bool os::is_headless_jre() { 5930 struct stat statbuf; 5931 char buf[MAXPATHLEN]; 5932 char libmawtpath[MAXPATHLEN]; 5933 const char *xawtstr = "/xawt/libmawt.so"; 5934 const char *new_xawtstr = "/libawt_xawt.so"; 5935 char *p; 5936 5937 // Get path to libjvm.so 5938 os::jvm_path(buf, sizeof(buf)); 5939 5940 // Get rid of libjvm.so 5941 p = strrchr(buf, '/'); 5942 if (p == NULL) return false; 5943 else *p = '\0'; 5944 5945 // Get rid of client or server 5946 p = strrchr(buf, '/'); 5947 if (p == NULL) return false; 5948 else *p = '\0'; 5949 5950 // check xawt/libmawt.so 5951 strcpy(libmawtpath, buf); 5952 strcat(libmawtpath, xawtstr); 5953 if (::stat(libmawtpath, &statbuf) == 0) return false; 5954 5955 // check libawt_xawt.so 5956 strcpy(libmawtpath, buf); 5957 strcat(libmawtpath, new_xawtstr); 5958 if (::stat(libmawtpath, &statbuf) == 0) return false; 5959 5960 return true; 5961 } 5962 5963 // Get the default path to the core file 5964 // Returns the length of the string 5965 int os::get_core_path(char* buffer, size_t bufferSize) { 5966 const char* p = get_current_directory(buffer, bufferSize); 5967 5968 if (p == NULL) { 5969 assert(p != NULL, "failed to get current directory"); 5970 return 0; 5971 } 5972 5973 return strlen(buffer); 5974 } 5975 5976 #ifdef JAVASE_EMBEDDED 5977 // 5978 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory. 5979 // 5980 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL; 5981 5982 // ctor 5983 // 5984 MemNotifyThread::MemNotifyThread(int fd): Thread() { 5985 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread"); 5986 _fd = fd; 5987 5988 if (os::create_thread(this, os::os_thread)) { 5989 _memnotify_thread = this; 5990 os::set_priority(this, NearMaxPriority); 5991 os::start_thread(this); 5992 } 5993 } 5994 5995 // Where all the work gets done 5996 // 5997 void MemNotifyThread::run() { 5998 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread"); 5999 6000 // Set up the select arguments 6001 fd_set rfds; 6002 if (_fd != -1) { 6003 FD_ZERO(&rfds); 6004 FD_SET(_fd, &rfds); 6005 } 6006 6007 // Now wait for the mem_notify device to wake up 6008 while (1) { 6009 // Wait for the mem_notify device to signal us.. 6010 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL); 6011 if (rc == -1) { 6012 perror("select!\n"); 6013 break; 6014 } else if (rc) { 6015 //ssize_t free_before = os::available_memory(); 6016 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024); 6017 6018 // The kernel is telling us there is not much memory left... 6019 // try to do something about that 6020 6021 // If we are not already in a GC, try one. 6022 if (!Universe::heap()->is_gc_active()) { 6023 Universe::heap()->collect(GCCause::_allocation_failure); 6024 6025 //ssize_t free_after = os::available_memory(); 6026 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024); 6027 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024); 6028 } 6029 // We might want to do something like the following if we find the GC's are not helping... 6030 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true); 6031 } 6032 } 6033 } 6034 6035 // 6036 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it. 6037 // 6038 void MemNotifyThread::start() { 6039 int fd; 6040 fd = open ("/dev/mem_notify", O_RDONLY, 0); 6041 if (fd < 0) { 6042 return; 6043 } 6044 6045 if (memnotify_thread() == NULL) { 6046 new MemNotifyThread(fd); 6047 } 6048 } 6049 6050 #endif // JAVASE_EMBEDDED 6051 6052 6053 /////////////// Unit tests /////////////// 6054 6055 #ifndef PRODUCT 6056 6057 #define test_log(...) \ 6058 do {\ 6059 if (VerboseInternalVMTests) { \ 6060 tty->print_cr(__VA_ARGS__); \ 6061 tty->flush(); \ 6062 }\ 6063 } while (false) 6064 6065 class TestReserveMemorySpecial : AllStatic { 6066 public: 6067 static void small_page_write(void* addr, size_t size) { 6068 size_t page_size = os::vm_page_size(); 6069 6070 char* end = (char*)addr + size; 6071 for (char* p = (char*)addr; p < end; p += page_size) { 6072 *p = 1; 6073 } 6074 } 6075 6076 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6077 if (!UseHugeTLBFS) { 6078 return; 6079 } 6080 6081 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6082 6083 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6084 6085 if (addr != NULL) { 6086 small_page_write(addr, size); 6087 6088 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6089 } 6090 } 6091 6092 static void test_reserve_memory_special_huge_tlbfs_only() { 6093 if (!UseHugeTLBFS) { 6094 return; 6095 } 6096 6097 size_t lp = os::large_page_size(); 6098 6099 for (size_t size = lp; size <= lp * 10; size += lp) { 6100 test_reserve_memory_special_huge_tlbfs_only(size); 6101 } 6102 } 6103 6104 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) { 6105 if (!UseHugeTLBFS) { 6106 return; 6107 } 6108 6109 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")", 6110 size, alignment); 6111 6112 assert(size >= os::large_page_size(), "Incorrect input to test"); 6113 6114 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6115 6116 if (addr != NULL) { 6117 small_page_write(addr, size); 6118 6119 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6120 } 6121 } 6122 6123 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) { 6124 size_t lp = os::large_page_size(); 6125 size_t ag = os::vm_allocation_granularity(); 6126 6127 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6128 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment); 6129 } 6130 } 6131 6132 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6133 size_t lp = os::large_page_size(); 6134 size_t ag = os::vm_allocation_granularity(); 6135 6136 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp); 6137 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag); 6138 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2); 6139 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2); 6140 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag); 6141 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag); 6142 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2); 6143 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10); 6144 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2); 6145 } 6146 6147 static void test_reserve_memory_special_huge_tlbfs() { 6148 if (!UseHugeTLBFS) { 6149 return; 6150 } 6151 6152 test_reserve_memory_special_huge_tlbfs_only(); 6153 test_reserve_memory_special_huge_tlbfs_mixed(); 6154 } 6155 6156 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6157 if (!UseSHM) { 6158 return; 6159 } 6160 6161 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6162 6163 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6164 6165 if (addr != NULL) { 6166 assert(is_ptr_aligned(addr, alignment), "Check"); 6167 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6168 6169 small_page_write(addr, size); 6170 6171 os::Linux::release_memory_special_shm(addr, size); 6172 } 6173 } 6174 6175 static void test_reserve_memory_special_shm() { 6176 size_t lp = os::large_page_size(); 6177 size_t ag = os::vm_allocation_granularity(); 6178 6179 for (size_t size = ag; size < lp * 3; size += ag) { 6180 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6181 test_reserve_memory_special_shm(size, alignment); 6182 } 6183 } 6184 } 6185 6186 static void test() { 6187 test_reserve_memory_special_huge_tlbfs(); 6188 test_reserve_memory_special_shm(); 6189 } 6190 }; 6191 6192 void TestReserveMemorySpecial_test() { 6193 TestReserveMemorySpecial::test(); 6194 } 6195 6196 #endif