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/orderAccess.inline.hpp" 53 #include "runtime/osThread.hpp" 54 #include "runtime/perfMemory.hpp" 55 #include "runtime/sharedRuntime.hpp" 56 #include "runtime/statSampler.hpp" 57 #include "runtime/stubRoutines.hpp" 58 #include "runtime/thread.inline.hpp" 59 #include "runtime/threadCritical.hpp" 60 #include "runtime/timer.hpp" 61 #include "services/attachListener.hpp" 62 #include "services/memTracker.hpp" 63 #include "services/runtimeService.hpp" 64 #include "utilities/decoder.hpp" 65 #include "utilities/defaultStream.hpp" 66 #include "utilities/events.hpp" 67 #include "utilities/elfFile.hpp" 68 #include "utilities/growableArray.hpp" 69 #include "utilities/vmError.hpp" 70 71 // put OS-includes here 72 # include <sys/types.h> 73 # include <sys/mman.h> 74 # include <sys/stat.h> 75 # include <sys/select.h> 76 # include <pthread.h> 77 # include <signal.h> 78 # include <errno.h> 79 # include <dlfcn.h> 80 # include <stdio.h> 81 # include <unistd.h> 82 # include <sys/resource.h> 83 # include <pthread.h> 84 # include <sys/stat.h> 85 # include <sys/time.h> 86 # include <sys/times.h> 87 # include <sys/utsname.h> 88 # include <sys/socket.h> 89 # include <sys/wait.h> 90 # include <pwd.h> 91 # include <poll.h> 92 # include <semaphore.h> 93 # include <fcntl.h> 94 # include <string.h> 95 # include <syscall.h> 96 # include <sys/sysinfo.h> 97 # include <gnu/libc-version.h> 98 # include <sys/ipc.h> 99 # include <sys/shm.h> 100 # include <link.h> 101 # include <stdint.h> 102 # include <inttypes.h> 103 # include <sys/ioctl.h> 104 105 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 106 107 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling 108 // getrusage() is prepared to handle the associated failure. 109 #ifndef RUSAGE_THREAD 110 #define RUSAGE_THREAD (1) /* only the calling thread */ 111 #endif 112 113 #define MAX_PATH (2 * K) 114 115 #define MAX_SECS 100000000 116 117 // for timer info max values which include all bits 118 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 119 120 #define LARGEPAGES_BIT (1 << 6) 121 //////////////////////////////////////////////////////////////////////////////// 122 // global variables 123 julong os::Linux::_physical_memory = 0; 124 125 address os::Linux::_initial_thread_stack_bottom = NULL; 126 uintptr_t os::Linux::_initial_thread_stack_size = 0; 127 128 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 129 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 130 Mutex* os::Linux::_createThread_lock = NULL; 131 pthread_t os::Linux::_main_thread; 132 int os::Linux::_page_size = -1; 133 const int os::Linux::_vm_default_page_size = (8 * K); 134 bool os::Linux::_is_floating_stack = false; 135 bool os::Linux::_is_NPTL = false; 136 bool os::Linux::_supports_fast_thread_cpu_time = false; 137 const char * os::Linux::_glibc_version = NULL; 138 const char * os::Linux::_libpthread_version = NULL; 139 pthread_condattr_t os::Linux::_condattr[1]; 140 141 static jlong initial_time_count=0; 142 143 static int clock_tics_per_sec = 100; 144 145 // For diagnostics to print a message once. see run_periodic_checks 146 static sigset_t check_signal_done; 147 static bool check_signals = true; 148 149 static pid_t _initial_pid = 0; 150 151 /* Signal number used to suspend/resume a thread */ 152 153 /* do not use any signal number less than SIGSEGV, see 4355769 */ 154 static int SR_signum = SIGUSR2; 155 sigset_t SR_sigset; 156 157 /* Used to protect dlsym() calls */ 158 static pthread_mutex_t dl_mutex; 159 160 // Declarations 161 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time); 162 163 #ifdef JAVASE_EMBEDDED 164 class MemNotifyThread: public Thread { 165 friend class VMStructs; 166 public: 167 virtual void run(); 168 169 private: 170 static MemNotifyThread* _memnotify_thread; 171 int _fd; 172 173 public: 174 175 // Constructor 176 MemNotifyThread(int fd); 177 178 // Tester 179 bool is_memnotify_thread() const { return true; } 180 181 // Printing 182 char* name() const { return (char*)"Linux MemNotify Thread"; } 183 184 // Returns the single instance of the MemNotifyThread 185 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; } 186 187 // Create and start the single instance of MemNotifyThread 188 static void start(); 189 }; 190 #endif // JAVASE_EMBEDDED 191 192 // utility functions 193 194 static int SR_initialize(); 195 196 julong os::available_memory() { 197 return Linux::available_memory(); 198 } 199 200 julong os::Linux::available_memory() { 201 // values in struct sysinfo are "unsigned long" 202 struct sysinfo si; 203 sysinfo(&si); 204 205 return (julong)si.freeram * si.mem_unit; 206 } 207 208 julong os::physical_memory() { 209 return Linux::physical_memory(); 210 } 211 212 //////////////////////////////////////////////////////////////////////////////// 213 // environment support 214 215 bool os::getenv(const char* name, char* buf, int len) { 216 const char* val = ::getenv(name); 217 if (val != NULL && strlen(val) < (size_t)len) { 218 strcpy(buf, val); 219 return true; 220 } 221 if (len > 0) buf[0] = 0; // return a null string 222 return false; 223 } 224 225 226 // Return true if user is running as root. 227 228 bool os::have_special_privileges() { 229 static bool init = false; 230 static bool privileges = false; 231 if (!init) { 232 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 233 init = true; 234 } 235 return privileges; 236 } 237 238 239 #ifndef SYS_gettid 240 // i386: 224, ia64: 1105, amd64: 186, sparc 143 241 #ifdef __ia64__ 242 #define SYS_gettid 1105 243 #elif __i386__ 244 #define SYS_gettid 224 245 #elif __amd64__ 246 #define SYS_gettid 186 247 #elif __sparc__ 248 #define SYS_gettid 143 249 #else 250 #error define gettid for the arch 251 #endif 252 #endif 253 254 // Cpu architecture string 255 #if defined(ZERO) 256 static char cpu_arch[] = ZERO_LIBARCH; 257 #elif defined(IA64) 258 static char cpu_arch[] = "ia64"; 259 #elif defined(IA32) 260 static char cpu_arch[] = "i386"; 261 #elif defined(AMD64) 262 static char cpu_arch[] = "amd64"; 263 #elif defined(ARM) 264 static char cpu_arch[] = "arm"; 265 #elif defined(PPC32) 266 static char cpu_arch[] = "ppc"; 267 #elif defined(PPC64) 268 static char cpu_arch[] = "ppc64"; 269 #elif defined(SPARC) 270 # ifdef _LP64 271 static char cpu_arch[] = "sparcv9"; 272 # else 273 static char cpu_arch[] = "sparc"; 274 # endif 275 #else 276 #error Add appropriate cpu_arch setting 277 #endif 278 279 280 // pid_t gettid() 281 // 282 // Returns the kernel thread id of the currently running thread. Kernel 283 // thread id is used to access /proc. 284 // 285 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 286 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 287 // 288 pid_t os::Linux::gettid() { 289 int rslt = syscall(SYS_gettid); 290 if (rslt == -1) { 291 // old kernel, no NPTL support 292 return getpid(); 293 } else { 294 return (pid_t)rslt; 295 } 296 } 297 298 // Most versions of linux have a bug where the number of processors are 299 // determined by looking at the /proc file system. In a chroot environment, 300 // the system call returns 1. This causes the VM to act as if it is 301 // a single processor and elide locking (see is_MP() call). 302 static bool unsafe_chroot_detected = false; 303 static const char *unstable_chroot_error = "/proc file system not found.\n" 304 "Java may be unstable running multithreaded in a chroot " 305 "environment on Linux when /proc filesystem is not mounted."; 306 307 void os::Linux::initialize_system_info() { 308 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 309 if (processor_count() == 1) { 310 pid_t pid = os::Linux::gettid(); 311 char fname[32]; 312 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 313 FILE *fp = fopen(fname, "r"); 314 if (fp == NULL) { 315 unsafe_chroot_detected = true; 316 } else { 317 fclose(fp); 318 } 319 } 320 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 321 assert(processor_count() > 0, "linux error"); 322 } 323 324 void os::init_system_properties_values() { 325 // The next steps are taken in the product version: 326 // 327 // Obtain the JAVA_HOME value from the location of libjvm.so. 328 // This library should be located at: 329 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 330 // 331 // If "/jre/lib/" appears at the right place in the path, then we 332 // assume libjvm.so is installed in a JDK and we use this path. 333 // 334 // Otherwise exit with message: "Could not create the Java virtual machine." 335 // 336 // The following extra steps are taken in the debugging version: 337 // 338 // If "/jre/lib/" does NOT appear at the right place in the path 339 // instead of exit check for $JAVA_HOME environment variable. 340 // 341 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 342 // then we append a fake suffix "hotspot/libjvm.so" to this path so 343 // it looks like libjvm.so is installed there 344 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 345 // 346 // Otherwise exit. 347 // 348 // Important note: if the location of libjvm.so changes this 349 // code needs to be changed accordingly. 350 351 // See ld(1): 352 // The linker uses the following search paths to locate required 353 // shared libraries: 354 // 1: ... 355 // ... 356 // 7: The default directories, normally /lib and /usr/lib. 357 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 358 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 359 #else 360 #define DEFAULT_LIBPATH "/lib:/usr/lib" 361 #endif 362 363 // Base path of extensions installed on the system. 364 #define SYS_EXT_DIR "/usr/java/packages" 365 #define EXTENSIONS_DIR "/lib/ext" 366 #define ENDORSED_DIR "/lib/endorsed" 367 368 // Buffer that fits several sprintfs. 369 // Note that the space for the colon and the trailing null are provided 370 // by the nulls included by the sizeof operator. 371 const size_t bufsize = 372 MAX3((size_t)MAXPATHLEN, // For dll_dir & friends. 373 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir 374 (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir 375 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 376 377 // sysclasspath, java_home, dll_dir 378 { 379 char *pslash; 380 os::jvm_path(buf, bufsize); 381 382 // Found the full path to libjvm.so. 383 // Now cut the path to <java_home>/jre if we can. 384 *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so. 385 pslash = strrchr(buf, '/'); 386 if (pslash != NULL) { 387 *pslash = '\0'; // Get rid of /{client|server|hotspot}. 388 } 389 Arguments::set_dll_dir(buf); 390 391 if (pslash != NULL) { 392 pslash = strrchr(buf, '/'); 393 if (pslash != NULL) { 394 *pslash = '\0'; // Get rid of /<arch>. 395 pslash = strrchr(buf, '/'); 396 if (pslash != NULL) { 397 *pslash = '\0'; // Get rid of /lib. 398 } 399 } 400 } 401 Arguments::set_java_home(buf); 402 set_boot_path('/', ':'); 403 } 404 405 // Where to look for native libraries. 406 // 407 // Note: Due to a legacy implementation, most of the library path 408 // is set in the launcher. This was to accomodate linking restrictions 409 // on legacy Linux implementations (which are no longer supported). 410 // Eventually, all the library path setting will be done here. 411 // 412 // However, to prevent the proliferation of improperly built native 413 // libraries, the new path component /usr/java/packages is added here. 414 // Eventually, all the library path setting will be done here. 415 { 416 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It 417 // should always exist (until the legacy problem cited above is 418 // addressed). 419 const char *v = ::getenv("LD_LIBRARY_PATH"); 420 const char *v_colon = ":"; 421 if (v == NULL) { v = ""; v_colon = ""; } 422 // That's +1 for the colon and +1 for the trailing '\0'. 423 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char, 424 strlen(v) + 1 + 425 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1, 426 mtInternal); 427 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch); 428 Arguments::set_library_path(ld_library_path); 429 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal); 430 } 431 432 // Extensions directories. 433 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home()); 434 Arguments::set_ext_dirs(buf); 435 436 // Endorsed standards default directory. 437 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 438 Arguments::set_endorsed_dirs(buf); 439 440 FREE_C_HEAP_ARRAY(char, buf, mtInternal); 441 442 #undef DEFAULT_LIBPATH 443 #undef SYS_EXT_DIR 444 #undef EXTENSIONS_DIR 445 #undef ENDORSED_DIR 446 } 447 448 //////////////////////////////////////////////////////////////////////////////// 449 // breakpoint support 450 451 void os::breakpoint() { 452 BREAKPOINT; 453 } 454 455 extern "C" void breakpoint() { 456 // use debugger to set breakpoint here 457 } 458 459 //////////////////////////////////////////////////////////////////////////////// 460 // signal support 461 462 debug_only(static bool signal_sets_initialized = false); 463 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 464 465 bool os::Linux::is_sig_ignored(int sig) { 466 struct sigaction oact; 467 sigaction(sig, (struct sigaction*)NULL, &oact); 468 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 469 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 470 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 471 return true; 472 else 473 return false; 474 } 475 476 void os::Linux::signal_sets_init() { 477 // Should also have an assertion stating we are still single-threaded. 478 assert(!signal_sets_initialized, "Already initialized"); 479 // Fill in signals that are necessarily unblocked for all threads in 480 // the VM. Currently, we unblock the following signals: 481 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 482 // by -Xrs (=ReduceSignalUsage)); 483 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 484 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 485 // the dispositions or masks wrt these signals. 486 // Programs embedding the VM that want to use the above signals for their 487 // own purposes must, at this time, use the "-Xrs" option to prevent 488 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 489 // (See bug 4345157, and other related bugs). 490 // In reality, though, unblocking these signals is really a nop, since 491 // these signals are not blocked by default. 492 sigemptyset(&unblocked_sigs); 493 sigemptyset(&allowdebug_blocked_sigs); 494 sigaddset(&unblocked_sigs, SIGILL); 495 sigaddset(&unblocked_sigs, SIGSEGV); 496 sigaddset(&unblocked_sigs, SIGBUS); 497 sigaddset(&unblocked_sigs, SIGFPE); 498 #if defined(PPC64) 499 sigaddset(&unblocked_sigs, SIGTRAP); 500 #endif 501 sigaddset(&unblocked_sigs, SR_signum); 502 503 if (!ReduceSignalUsage) { 504 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 505 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 506 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 507 } 508 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 509 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 510 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 511 } 512 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 513 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 514 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 515 } 516 } 517 // Fill in signals that are blocked by all but the VM thread. 518 sigemptyset(&vm_sigs); 519 if (!ReduceSignalUsage) 520 sigaddset(&vm_sigs, BREAK_SIGNAL); 521 debug_only(signal_sets_initialized = true); 522 523 } 524 525 // These are signals that are unblocked while a thread is running Java. 526 // (For some reason, they get blocked by default.) 527 sigset_t* os::Linux::unblocked_signals() { 528 assert(signal_sets_initialized, "Not initialized"); 529 return &unblocked_sigs; 530 } 531 532 // These are the signals that are blocked while a (non-VM) thread is 533 // running Java. Only the VM thread handles these signals. 534 sigset_t* os::Linux::vm_signals() { 535 assert(signal_sets_initialized, "Not initialized"); 536 return &vm_sigs; 537 } 538 539 // These are signals that are blocked during cond_wait to allow debugger in 540 sigset_t* os::Linux::allowdebug_blocked_signals() { 541 assert(signal_sets_initialized, "Not initialized"); 542 return &allowdebug_blocked_sigs; 543 } 544 545 void os::Linux::hotspot_sigmask(Thread* thread) { 546 547 //Save caller's signal mask before setting VM signal mask 548 sigset_t caller_sigmask; 549 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 550 551 OSThread* osthread = thread->osthread(); 552 osthread->set_caller_sigmask(caller_sigmask); 553 554 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 555 556 if (!ReduceSignalUsage) { 557 if (thread->is_VM_thread()) { 558 // Only the VM thread handles BREAK_SIGNAL ... 559 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 560 } else { 561 // ... all other threads block BREAK_SIGNAL 562 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 563 } 564 } 565 } 566 567 ////////////////////////////////////////////////////////////////////////////// 568 // detecting pthread library 569 570 void os::Linux::libpthread_init() { 571 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 572 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 573 // generic name for earlier versions. 574 // Define macros here so we can build HotSpot on old systems. 575 # ifndef _CS_GNU_LIBC_VERSION 576 # define _CS_GNU_LIBC_VERSION 2 577 # endif 578 # ifndef _CS_GNU_LIBPTHREAD_VERSION 579 # define _CS_GNU_LIBPTHREAD_VERSION 3 580 # endif 581 582 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 583 if (n > 0) { 584 char *str = (char *)malloc(n, mtInternal); 585 confstr(_CS_GNU_LIBC_VERSION, str, n); 586 os::Linux::set_glibc_version(str); 587 } else { 588 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 589 static char _gnu_libc_version[32]; 590 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 591 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 592 os::Linux::set_glibc_version(_gnu_libc_version); 593 } 594 595 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 596 if (n > 0) { 597 char *str = (char *)malloc(n, mtInternal); 598 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 599 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 600 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 601 // is the case. LinuxThreads has a hard limit on max number of threads. 602 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 603 // On the other hand, NPTL does not have such a limit, sysconf() 604 // will return -1 and errno is not changed. Check if it is really NPTL. 605 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 606 strstr(str, "NPTL") && 607 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 608 free(str); 609 os::Linux::set_libpthread_version("linuxthreads"); 610 } else { 611 os::Linux::set_libpthread_version(str); 612 } 613 } else { 614 // glibc before 2.3.2 only has LinuxThreads. 615 os::Linux::set_libpthread_version("linuxthreads"); 616 } 617 618 if (strstr(libpthread_version(), "NPTL")) { 619 os::Linux::set_is_NPTL(); 620 } else { 621 os::Linux::set_is_LinuxThreads(); 622 } 623 624 // LinuxThreads have two flavors: floating-stack mode, which allows variable 625 // stack size; and fixed-stack mode. NPTL is always floating-stack. 626 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 627 os::Linux::set_is_floating_stack(); 628 } 629 } 630 631 ///////////////////////////////////////////////////////////////////////////// 632 // thread stack 633 634 // Force Linux kernel to expand current thread stack. If "bottom" is close 635 // to the stack guard, caller should block all signals. 636 // 637 // MAP_GROWSDOWN: 638 // A special mmap() flag that is used to implement thread stacks. It tells 639 // kernel that the memory region should extend downwards when needed. This 640 // allows early versions of LinuxThreads to only mmap the first few pages 641 // when creating a new thread. Linux kernel will automatically expand thread 642 // stack as needed (on page faults). 643 // 644 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 645 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 646 // region, it's hard to tell if the fault is due to a legitimate stack 647 // access or because of reading/writing non-exist memory (e.g. buffer 648 // overrun). As a rule, if the fault happens below current stack pointer, 649 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 650 // application (see Linux kernel fault.c). 651 // 652 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 653 // stack overflow detection. 654 // 655 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 656 // not use this flag. However, the stack of initial thread is not created 657 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 658 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 659 // and then attach the thread to JVM. 660 // 661 // To get around the problem and allow stack banging on Linux, we need to 662 // manually expand thread stack after receiving the SIGSEGV. 663 // 664 // There are two ways to expand thread stack to address "bottom", we used 665 // both of them in JVM before 1.5: 666 // 1. adjust stack pointer first so that it is below "bottom", and then 667 // touch "bottom" 668 // 2. mmap() the page in question 669 // 670 // Now alternate signal stack is gone, it's harder to use 2. For instance, 671 // if current sp is already near the lower end of page 101, and we need to 672 // call mmap() to map page 100, it is possible that part of the mmap() frame 673 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 674 // That will destroy the mmap() frame and cause VM to crash. 675 // 676 // The following code works by adjusting sp first, then accessing the "bottom" 677 // page to force a page fault. Linux kernel will then automatically expand the 678 // stack mapping. 679 // 680 // _expand_stack_to() assumes its frame size is less than page size, which 681 // should always be true if the function is not inlined. 682 683 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 684 #define NOINLINE 685 #else 686 #define NOINLINE __attribute__ ((noinline)) 687 #endif 688 689 static void _expand_stack_to(address bottom) NOINLINE; 690 691 static void _expand_stack_to(address bottom) { 692 address sp; 693 size_t size; 694 volatile char *p; 695 696 // Adjust bottom to point to the largest address within the same page, it 697 // gives us a one-page buffer if alloca() allocates slightly more memory. 698 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 699 bottom += os::Linux::page_size() - 1; 700 701 // sp might be slightly above current stack pointer; if that's the case, we 702 // will alloca() a little more space than necessary, which is OK. Don't use 703 // os::current_stack_pointer(), as its result can be slightly below current 704 // stack pointer, causing us to not alloca enough to reach "bottom". 705 sp = (address)&sp; 706 707 if (sp > bottom) { 708 size = sp - bottom; 709 p = (volatile char *)alloca(size); 710 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 711 p[0] = '\0'; 712 } 713 } 714 715 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 716 assert(t!=NULL, "just checking"); 717 assert(t->osthread()->expanding_stack(), "expand should be set"); 718 assert(t->stack_base() != NULL, "stack_base was not initialized"); 719 720 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 721 sigset_t mask_all, old_sigset; 722 sigfillset(&mask_all); 723 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 724 _expand_stack_to(addr); 725 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 726 return true; 727 } 728 return false; 729 } 730 731 ////////////////////////////////////////////////////////////////////////////// 732 // create new thread 733 734 static address highest_vm_reserved_address(); 735 736 // check if it's safe to start a new thread 737 static bool _thread_safety_check(Thread* thread) { 738 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 739 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 740 // Heap is mmap'ed at lower end of memory space. Thread stacks are 741 // allocated (MAP_FIXED) from high address space. Every thread stack 742 // occupies a fixed size slot (usually 2Mbytes, but user can change 743 // it to other values if they rebuild LinuxThreads). 744 // 745 // Problem with MAP_FIXED is that mmap() can still succeed even part of 746 // the memory region has already been mmap'ed. That means if we have too 747 // many threads and/or very large heap, eventually thread stack will 748 // collide with heap. 749 // 750 // Here we try to prevent heap/stack collision by comparing current 751 // stack bottom with the highest address that has been mmap'ed by JVM 752 // plus a safety margin for memory maps created by native code. 753 // 754 // This feature can be disabled by setting ThreadSafetyMargin to 0 755 // 756 if (ThreadSafetyMargin > 0) { 757 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 758 759 // not safe if our stack extends below the safety margin 760 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 761 } else { 762 return true; 763 } 764 } else { 765 // Floating stack LinuxThreads or NPTL: 766 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 767 // there's not enough space left, pthread_create() will fail. If we come 768 // here, that means enough space has been reserved for stack. 769 return true; 770 } 771 } 772 773 // Thread start routine for all newly created threads 774 static void *java_start(Thread *thread) { 775 // Try to randomize the cache line index of hot stack frames. 776 // This helps when threads of the same stack traces evict each other's 777 // cache lines. The threads can be either from the same JVM instance, or 778 // from different JVM instances. The benefit is especially true for 779 // processors with hyperthreading technology. 780 static int counter = 0; 781 int pid = os::current_process_id(); 782 alloca(((pid ^ counter++) & 7) * 128); 783 784 ThreadLocalStorage::set_thread(thread); 785 786 OSThread* osthread = thread->osthread(); 787 Monitor* sync = osthread->startThread_lock(); 788 789 // non floating stack LinuxThreads needs extra check, see above 790 if (!_thread_safety_check(thread)) { 791 // notify parent thread 792 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 793 osthread->set_state(ZOMBIE); 794 sync->notify_all(); 795 return NULL; 796 } 797 798 // thread_id is kernel thread id (similar to Solaris LWP id) 799 osthread->set_thread_id(os::Linux::gettid()); 800 801 if (UseNUMA) { 802 int lgrp_id = os::numa_get_group_id(); 803 if (lgrp_id != -1) { 804 thread->set_lgrp_id(lgrp_id); 805 } 806 } 807 // initialize signal mask for this thread 808 os::Linux::hotspot_sigmask(thread); 809 810 // initialize floating point control register 811 os::Linux::init_thread_fpu_state(); 812 813 // handshaking with parent thread 814 { 815 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 816 817 // notify parent thread 818 osthread->set_state(INITIALIZED); 819 sync->notify_all(); 820 821 // wait until os::start_thread() 822 while (osthread->get_state() == INITIALIZED) { 823 sync->wait(Mutex::_no_safepoint_check_flag); 824 } 825 } 826 827 // call one more level start routine 828 thread->run(); 829 830 return 0; 831 } 832 833 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 834 assert(thread->osthread() == NULL, "caller responsible"); 835 836 // Allocate the OSThread object 837 OSThread* osthread = new OSThread(NULL, NULL); 838 if (osthread == NULL) { 839 return false; 840 } 841 842 // set the correct thread state 843 osthread->set_thread_type(thr_type); 844 845 // Initial state is ALLOCATED but not INITIALIZED 846 osthread->set_state(ALLOCATED); 847 848 thread->set_osthread(osthread); 849 850 // init thread attributes 851 pthread_attr_t attr; 852 pthread_attr_init(&attr); 853 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 854 855 // stack size 856 if (os::Linux::supports_variable_stack_size()) { 857 // calculate stack size if it's not specified by caller 858 if (stack_size == 0) { 859 stack_size = os::Linux::default_stack_size(thr_type); 860 861 switch (thr_type) { 862 case os::java_thread: 863 // Java threads use ThreadStackSize which default value can be 864 // changed with the flag -Xss 865 assert (JavaThread::stack_size_at_create() > 0, "this should be set"); 866 stack_size = JavaThread::stack_size_at_create(); 867 break; 868 case os::compiler_thread: 869 if (CompilerThreadStackSize > 0) { 870 stack_size = (size_t)(CompilerThreadStackSize * K); 871 break; 872 } // else fall through: 873 // use VMThreadStackSize if CompilerThreadStackSize is not defined 874 case os::vm_thread: 875 case os::pgc_thread: 876 case os::cgc_thread: 877 case os::watcher_thread: 878 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 879 break; 880 } 881 } 882 883 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 884 pthread_attr_setstacksize(&attr, stack_size); 885 } else { 886 // let pthread_create() pick the default value. 887 } 888 889 // glibc guard page 890 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 891 892 ThreadState state; 893 894 { 895 // Serialize thread creation if we are running with fixed stack LinuxThreads 896 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 897 if (lock) { 898 os::Linux::createThread_lock()->lock_without_safepoint_check(); 899 } 900 901 pthread_t tid; 902 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 903 904 pthread_attr_destroy(&attr); 905 906 if (ret != 0) { 907 if (PrintMiscellaneous && (Verbose || WizardMode)) { 908 perror("pthread_create()"); 909 } 910 // Need to clean up stuff we've allocated so far 911 thread->set_osthread(NULL); 912 delete osthread; 913 if (lock) os::Linux::createThread_lock()->unlock(); 914 return false; 915 } 916 917 // Store pthread info into the OSThread 918 osthread->set_pthread_id(tid); 919 920 // Wait until child thread is either initialized or aborted 921 { 922 Monitor* sync_with_child = osthread->startThread_lock(); 923 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 924 while ((state = osthread->get_state()) == ALLOCATED) { 925 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 926 } 927 } 928 929 if (lock) { 930 os::Linux::createThread_lock()->unlock(); 931 } 932 } 933 934 // Aborted due to thread limit being reached 935 if (state == ZOMBIE) { 936 thread->set_osthread(NULL); 937 delete osthread; 938 return false; 939 } 940 941 // The thread is returned suspended (in state INITIALIZED), 942 // and is started higher up in the call chain 943 assert(state == INITIALIZED, "race condition"); 944 return true; 945 } 946 947 ///////////////////////////////////////////////////////////////////////////// 948 // attach existing thread 949 950 // bootstrap the main thread 951 bool os::create_main_thread(JavaThread* thread) { 952 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 953 return create_attached_thread(thread); 954 } 955 956 bool os::create_attached_thread(JavaThread* thread) { 957 #ifdef ASSERT 958 thread->verify_not_published(); 959 #endif 960 961 // Allocate the OSThread object 962 OSThread* osthread = new OSThread(NULL, NULL); 963 964 if (osthread == NULL) { 965 return false; 966 } 967 968 // Store pthread info into the OSThread 969 osthread->set_thread_id(os::Linux::gettid()); 970 osthread->set_pthread_id(::pthread_self()); 971 972 // initialize floating point control register 973 os::Linux::init_thread_fpu_state(); 974 975 // Initial thread state is RUNNABLE 976 osthread->set_state(RUNNABLE); 977 978 thread->set_osthread(osthread); 979 980 if (UseNUMA) { 981 int lgrp_id = os::numa_get_group_id(); 982 if (lgrp_id != -1) { 983 thread->set_lgrp_id(lgrp_id); 984 } 985 } 986 987 if (os::Linux::is_initial_thread()) { 988 // If current thread is initial thread, its stack is mapped on demand, 989 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 990 // the entire stack region to avoid SEGV in stack banging. 991 // It is also useful to get around the heap-stack-gap problem on SuSE 992 // kernel (see 4821821 for details). We first expand stack to the top 993 // of yellow zone, then enable stack yellow zone (order is significant, 994 // enabling yellow zone first will crash JVM on SuSE Linux), so there 995 // is no gap between the last two virtual memory regions. 996 997 JavaThread *jt = (JavaThread *)thread; 998 address addr = jt->stack_yellow_zone_base(); 999 assert(addr != NULL, "initialization problem?"); 1000 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 1001 1002 osthread->set_expanding_stack(); 1003 os::Linux::manually_expand_stack(jt, addr); 1004 osthread->clear_expanding_stack(); 1005 } 1006 1007 // initialize signal mask for this thread 1008 // and save the caller's signal mask 1009 os::Linux::hotspot_sigmask(thread); 1010 1011 return true; 1012 } 1013 1014 void os::pd_start_thread(Thread* thread) { 1015 OSThread * osthread = thread->osthread(); 1016 assert(osthread->get_state() != INITIALIZED, "just checking"); 1017 Monitor* sync_with_child = osthread->startThread_lock(); 1018 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 1019 sync_with_child->notify(); 1020 } 1021 1022 // Free Linux resources related to the OSThread 1023 void os::free_thread(OSThread* osthread) { 1024 assert(osthread != NULL, "osthread not set"); 1025 1026 if (Thread::current()->osthread() == osthread) { 1027 // Restore caller's signal mask 1028 sigset_t sigmask = osthread->caller_sigmask(); 1029 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1030 } 1031 1032 delete osthread; 1033 } 1034 1035 ////////////////////////////////////////////////////////////////////////////// 1036 // thread local storage 1037 1038 // Restore the thread pointer if the destructor is called. This is in case 1039 // someone from JNI code sets up a destructor with pthread_key_create to run 1040 // detachCurrentThread on thread death. Unless we restore the thread pointer we 1041 // will hang or crash. When detachCurrentThread is called the key will be set 1042 // to null and we will not be called again. If detachCurrentThread is never 1043 // called we could loop forever depending on the pthread implementation. 1044 static void restore_thread_pointer(void* p) { 1045 Thread* thread = (Thread*) p; 1046 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); 1047 } 1048 1049 int os::allocate_thread_local_storage() { 1050 pthread_key_t key; 1051 int rslt = pthread_key_create(&key, restore_thread_pointer); 1052 assert(rslt == 0, "cannot allocate thread local storage"); 1053 return (int)key; 1054 } 1055 1056 // Note: This is currently not used by VM, as we don't destroy TLS key 1057 // on VM exit. 1058 void os::free_thread_local_storage(int index) { 1059 int rslt = pthread_key_delete((pthread_key_t)index); 1060 assert(rslt == 0, "invalid index"); 1061 } 1062 1063 void os::thread_local_storage_at_put(int index, void* value) { 1064 int rslt = pthread_setspecific((pthread_key_t)index, value); 1065 assert(rslt == 0, "pthread_setspecific failed"); 1066 } 1067 1068 extern "C" Thread* get_thread() { 1069 return ThreadLocalStorage::thread(); 1070 } 1071 1072 ////////////////////////////////////////////////////////////////////////////// 1073 // initial thread 1074 1075 // Check if current thread is the initial thread, similar to Solaris thr_main. 1076 bool os::Linux::is_initial_thread(void) { 1077 char dummy; 1078 // If called before init complete, thread stack bottom will be null. 1079 // Can be called if fatal error occurs before initialization. 1080 if (initial_thread_stack_bottom() == NULL) return false; 1081 assert(initial_thread_stack_bottom() != NULL && 1082 initial_thread_stack_size() != 0, 1083 "os::init did not locate initial thread's stack region"); 1084 if ((address)&dummy >= initial_thread_stack_bottom() && 1085 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1086 return true; 1087 else return false; 1088 } 1089 1090 // Find the virtual memory area that contains addr 1091 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1092 FILE *fp = fopen("/proc/self/maps", "r"); 1093 if (fp) { 1094 address low, high; 1095 while (!feof(fp)) { 1096 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1097 if (low <= addr && addr < high) { 1098 if (vma_low) *vma_low = low; 1099 if (vma_high) *vma_high = high; 1100 fclose (fp); 1101 return true; 1102 } 1103 } 1104 for (;;) { 1105 int ch = fgetc(fp); 1106 if (ch == EOF || ch == (int)'\n') break; 1107 } 1108 } 1109 fclose(fp); 1110 } 1111 return false; 1112 } 1113 1114 // Locate initial thread stack. This special handling of initial thread stack 1115 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1116 // bogus value for initial thread. 1117 void os::Linux::capture_initial_stack(size_t max_size) { 1118 // stack size is the easy part, get it from RLIMIT_STACK 1119 size_t stack_size; 1120 struct rlimit rlim; 1121 getrlimit(RLIMIT_STACK, &rlim); 1122 stack_size = rlim.rlim_cur; 1123 1124 // 6308388: a bug in ld.so will relocate its own .data section to the 1125 // lower end of primordial stack; reduce ulimit -s value a little bit 1126 // so we won't install guard page on ld.so's data section. 1127 stack_size -= 2 * page_size(); 1128 1129 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1130 // 7.1, in both cases we will get 2G in return value. 1131 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1132 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1133 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1134 // in case other parts in glibc still assumes 2M max stack size. 1135 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1136 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1137 if (stack_size > 2 * K * K IA64_ONLY(*2)) 1138 stack_size = 2 * K * K IA64_ONLY(*2); 1139 // Try to figure out where the stack base (top) is. This is harder. 1140 // 1141 // When an application is started, glibc saves the initial stack pointer in 1142 // a global variable "__libc_stack_end", which is then used by system 1143 // libraries. __libc_stack_end should be pretty close to stack top. The 1144 // variable is available since the very early days. However, because it is 1145 // a private interface, it could disappear in the future. 1146 // 1147 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1148 // to __libc_stack_end, it is very close to stack top, but isn't the real 1149 // stack top. Note that /proc may not exist if VM is running as a chroot 1150 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1151 // /proc/<pid>/stat could change in the future (though unlikely). 1152 // 1153 // We try __libc_stack_end first. If that doesn't work, look for 1154 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1155 // as a hint, which should work well in most cases. 1156 1157 uintptr_t stack_start; 1158 1159 // try __libc_stack_end first 1160 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1161 if (p && *p) { 1162 stack_start = *p; 1163 } else { 1164 // see if we can get the start_stack field from /proc/self/stat 1165 FILE *fp; 1166 int pid; 1167 char state; 1168 int ppid; 1169 int pgrp; 1170 int session; 1171 int nr; 1172 int tpgrp; 1173 unsigned long flags; 1174 unsigned long minflt; 1175 unsigned long cminflt; 1176 unsigned long majflt; 1177 unsigned long cmajflt; 1178 unsigned long utime; 1179 unsigned long stime; 1180 long cutime; 1181 long cstime; 1182 long prio; 1183 long nice; 1184 long junk; 1185 long it_real; 1186 uintptr_t start; 1187 uintptr_t vsize; 1188 intptr_t rss; 1189 uintptr_t rsslim; 1190 uintptr_t scodes; 1191 uintptr_t ecode; 1192 int i; 1193 1194 // Figure what the primordial thread stack base is. Code is inspired 1195 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1196 // followed by command name surrounded by parentheses, state, etc. 1197 char stat[2048]; 1198 int statlen; 1199 1200 fp = fopen("/proc/self/stat", "r"); 1201 if (fp) { 1202 statlen = fread(stat, 1, 2047, fp); 1203 stat[statlen] = '\0'; 1204 fclose(fp); 1205 1206 // Skip pid and the command string. Note that we could be dealing with 1207 // weird command names, e.g. user could decide to rename java launcher 1208 // to "java 1.4.2 :)", then the stat file would look like 1209 // 1234 (java 1.4.2 :)) R ... ... 1210 // We don't really need to know the command string, just find the last 1211 // occurrence of ")" and then start parsing from there. See bug 4726580. 1212 char * s = strrchr(stat, ')'); 1213 1214 i = 0; 1215 if (s) { 1216 // Skip blank chars 1217 do s++; while (isspace(*s)); 1218 1219 #define _UFM UINTX_FORMAT 1220 #define _DFM INTX_FORMAT 1221 1222 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1223 /* 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 */ 1224 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, 1225 &state, /* 3 %c */ 1226 &ppid, /* 4 %d */ 1227 &pgrp, /* 5 %d */ 1228 &session, /* 6 %d */ 1229 &nr, /* 7 %d */ 1230 &tpgrp, /* 8 %d */ 1231 &flags, /* 9 %lu */ 1232 &minflt, /* 10 %lu */ 1233 &cminflt, /* 11 %lu */ 1234 &majflt, /* 12 %lu */ 1235 &cmajflt, /* 13 %lu */ 1236 &utime, /* 14 %lu */ 1237 &stime, /* 15 %lu */ 1238 &cutime, /* 16 %ld */ 1239 &cstime, /* 17 %ld */ 1240 &prio, /* 18 %ld */ 1241 &nice, /* 19 %ld */ 1242 &junk, /* 20 %ld */ 1243 &it_real, /* 21 %ld */ 1244 &start, /* 22 UINTX_FORMAT */ 1245 &vsize, /* 23 UINTX_FORMAT */ 1246 &rss, /* 24 INTX_FORMAT */ 1247 &rsslim, /* 25 UINTX_FORMAT */ 1248 &scodes, /* 26 UINTX_FORMAT */ 1249 &ecode, /* 27 UINTX_FORMAT */ 1250 &stack_start); /* 28 UINTX_FORMAT */ 1251 } 1252 1253 #undef _UFM 1254 #undef _DFM 1255 1256 if (i != 28 - 2) { 1257 assert(false, "Bad conversion from /proc/self/stat"); 1258 // product mode - assume we are the initial thread, good luck in the 1259 // embedded case. 1260 warning("Can't detect initial thread stack location - bad conversion"); 1261 stack_start = (uintptr_t) &rlim; 1262 } 1263 } else { 1264 // For some reason we can't open /proc/self/stat (for example, running on 1265 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1266 // most cases, so don't abort: 1267 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1268 stack_start = (uintptr_t) &rlim; 1269 } 1270 } 1271 1272 // Now we have a pointer (stack_start) very close to the stack top, the 1273 // next thing to do is to figure out the exact location of stack top. We 1274 // can find out the virtual memory area that contains stack_start by 1275 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1276 // and its upper limit is the real stack top. (again, this would fail if 1277 // running inside chroot, because /proc may not exist.) 1278 1279 uintptr_t stack_top; 1280 address low, high; 1281 if (find_vma((address)stack_start, &low, &high)) { 1282 // success, "high" is the true stack top. (ignore "low", because initial 1283 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1284 stack_top = (uintptr_t)high; 1285 } else { 1286 // failed, likely because /proc/self/maps does not exist 1287 warning("Can't detect initial thread stack location - find_vma failed"); 1288 // best effort: stack_start is normally within a few pages below the real 1289 // stack top, use it as stack top, and reduce stack size so we won't put 1290 // guard page outside stack. 1291 stack_top = stack_start; 1292 stack_size -= 16 * page_size(); 1293 } 1294 1295 // stack_top could be partially down the page so align it 1296 stack_top = align_size_up(stack_top, page_size()); 1297 1298 if (max_size && stack_size > max_size) { 1299 _initial_thread_stack_size = max_size; 1300 } else { 1301 _initial_thread_stack_size = stack_size; 1302 } 1303 1304 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1305 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1306 } 1307 1308 //////////////////////////////////////////////////////////////////////////////// 1309 // time support 1310 1311 // Time since start-up in seconds to a fine granularity. 1312 // Used by VMSelfDestructTimer and the MemProfiler. 1313 double os::elapsedTime() { 1314 1315 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution 1316 } 1317 1318 jlong os::elapsed_counter() { 1319 return javaTimeNanos() - initial_time_count; 1320 } 1321 1322 jlong os::elapsed_frequency() { 1323 return NANOSECS_PER_SEC; // nanosecond resolution 1324 } 1325 1326 bool os::supports_vtime() { return true; } 1327 bool os::enable_vtime() { return false; } 1328 bool os::vtime_enabled() { return false; } 1329 1330 double os::elapsedVTime() { 1331 struct rusage usage; 1332 int retval = getrusage(RUSAGE_THREAD, &usage); 1333 if (retval == 0) { 1334 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); 1335 } else { 1336 // better than nothing, but not much 1337 return elapsedTime(); 1338 } 1339 } 1340 1341 jlong os::javaTimeMillis() { 1342 timeval time; 1343 int status = gettimeofday(&time, NULL); 1344 assert(status != -1, "linux error"); 1345 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1346 } 1347 1348 #ifndef CLOCK_MONOTONIC 1349 #define CLOCK_MONOTONIC (1) 1350 #endif 1351 1352 void os::Linux::clock_init() { 1353 // we do dlopen's in this particular order due to bug in linux 1354 // dynamical loader (see 6348968) leading to crash on exit 1355 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1356 if (handle == NULL) { 1357 handle = dlopen("librt.so", RTLD_LAZY); 1358 } 1359 1360 if (handle) { 1361 int (*clock_getres_func)(clockid_t, struct timespec*) = 1362 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1363 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1364 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1365 if (clock_getres_func && clock_gettime_func) { 1366 // See if monotonic clock is supported by the kernel. Note that some 1367 // early implementations simply return kernel jiffies (updated every 1368 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1369 // for nano time (though the monotonic property is still nice to have). 1370 // It's fixed in newer kernels, however clock_getres() still returns 1371 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1372 // resolution for now. Hopefully as people move to new kernels, this 1373 // won't be a problem. 1374 struct timespec res; 1375 struct timespec tp; 1376 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1377 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1378 // yes, monotonic clock is supported 1379 _clock_gettime = clock_gettime_func; 1380 return; 1381 } else { 1382 // close librt if there is no monotonic clock 1383 dlclose(handle); 1384 } 1385 } 1386 } 1387 warning("No monotonic clock was available - timed services may " \ 1388 "be adversely affected if the time-of-day clock changes"); 1389 } 1390 1391 #ifndef SYS_clock_getres 1392 1393 #if defined(IA32) || defined(AMD64) 1394 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1395 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1396 #else 1397 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1398 #define sys_clock_getres(x,y) -1 1399 #endif 1400 1401 #else 1402 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1403 #endif 1404 1405 void os::Linux::fast_thread_clock_init() { 1406 if (!UseLinuxPosixThreadCPUClocks) { 1407 return; 1408 } 1409 clockid_t clockid; 1410 struct timespec tp; 1411 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1412 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1413 1414 // Switch to using fast clocks for thread cpu time if 1415 // the sys_clock_getres() returns 0 error code. 1416 // Note, that some kernels may support the current thread 1417 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1418 // returned by the pthread_getcpuclockid(). 1419 // If the fast Posix clocks are supported then the sys_clock_getres() 1420 // must return at least tp.tv_sec == 0 which means a resolution 1421 // better than 1 sec. This is extra check for reliability. 1422 1423 if(pthread_getcpuclockid_func && 1424 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1425 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1426 1427 _supports_fast_thread_cpu_time = true; 1428 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1429 } 1430 } 1431 1432 jlong os::javaTimeNanos() { 1433 if (Linux::supports_monotonic_clock()) { 1434 struct timespec tp; 1435 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1436 assert(status == 0, "gettime error"); 1437 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1438 return result; 1439 } else { 1440 timeval time; 1441 int status = gettimeofday(&time, NULL); 1442 assert(status != -1, "linux error"); 1443 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1444 return 1000 * usecs; 1445 } 1446 } 1447 1448 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1449 if (Linux::supports_monotonic_clock()) { 1450 info_ptr->max_value = ALL_64_BITS; 1451 1452 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1453 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1454 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1455 } else { 1456 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1457 info_ptr->max_value = ALL_64_BITS; 1458 1459 // gettimeofday is a real time clock so it skips 1460 info_ptr->may_skip_backward = true; 1461 info_ptr->may_skip_forward = true; 1462 } 1463 1464 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1465 } 1466 1467 // Return the real, user, and system times in seconds from an 1468 // arbitrary fixed point in the past. 1469 bool os::getTimesSecs(double* process_real_time, 1470 double* process_user_time, 1471 double* process_system_time) { 1472 struct tms ticks; 1473 clock_t real_ticks = times(&ticks); 1474 1475 if (real_ticks == (clock_t) (-1)) { 1476 return false; 1477 } else { 1478 double ticks_per_second = (double) clock_tics_per_sec; 1479 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1480 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1481 *process_real_time = ((double) real_ticks) / ticks_per_second; 1482 1483 return true; 1484 } 1485 } 1486 1487 1488 char * os::local_time_string(char *buf, size_t buflen) { 1489 struct tm t; 1490 time_t long_time; 1491 time(&long_time); 1492 localtime_r(&long_time, &t); 1493 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1494 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1495 t.tm_hour, t.tm_min, t.tm_sec); 1496 return buf; 1497 } 1498 1499 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1500 return localtime_r(clock, res); 1501 } 1502 1503 //////////////////////////////////////////////////////////////////////////////// 1504 // runtime exit support 1505 1506 // Note: os::shutdown() might be called very early during initialization, or 1507 // called from signal handler. Before adding something to os::shutdown(), make 1508 // sure it is async-safe and can handle partially initialized VM. 1509 void os::shutdown() { 1510 1511 // allow PerfMemory to attempt cleanup of any persistent resources 1512 perfMemory_exit(); 1513 1514 // needs to remove object in file system 1515 AttachListener::abort(); 1516 1517 // flush buffered output, finish log files 1518 ostream_abort(); 1519 1520 // Check for abort hook 1521 abort_hook_t abort_hook = Arguments::abort_hook(); 1522 if (abort_hook != NULL) { 1523 abort_hook(); 1524 } 1525 1526 } 1527 1528 // Note: os::abort() might be called very early during initialization, or 1529 // called from signal handler. Before adding something to os::abort(), make 1530 // sure it is async-safe and can handle partially initialized VM. 1531 void os::abort(bool dump_core) { 1532 os::shutdown(); 1533 if (dump_core) { 1534 #ifndef PRODUCT 1535 fdStream out(defaultStream::output_fd()); 1536 out.print_raw("Current thread is "); 1537 char buf[16]; 1538 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1539 out.print_raw_cr(buf); 1540 out.print_raw_cr("Dumping core ..."); 1541 #endif 1542 ::abort(); // dump core 1543 } 1544 1545 ::exit(1); 1546 } 1547 1548 // Die immediately, no exit hook, no abort hook, no cleanup. 1549 void os::die() { 1550 // _exit() on LinuxThreads only kills current thread 1551 ::abort(); 1552 } 1553 1554 1555 // This method is a copy of JDK's sysGetLastErrorString 1556 // from src/solaris/hpi/src/system_md.c 1557 1558 size_t os::lasterror(char *buf, size_t len) { 1559 1560 if (errno == 0) return 0; 1561 1562 const char *s = ::strerror(errno); 1563 size_t n = ::strlen(s); 1564 if (n >= len) { 1565 n = len - 1; 1566 } 1567 ::strncpy(buf, s, n); 1568 buf[n] = '\0'; 1569 return n; 1570 } 1571 1572 intx os::current_thread_id() { return (intx)pthread_self(); } 1573 int os::current_process_id() { 1574 1575 // Under the old linux thread library, linux gives each thread 1576 // its own process id. Because of this each thread will return 1577 // a different pid if this method were to return the result 1578 // of getpid(2). Linux provides no api that returns the pid 1579 // of the launcher thread for the vm. This implementation 1580 // returns a unique pid, the pid of the launcher thread 1581 // that starts the vm 'process'. 1582 1583 // Under the NPTL, getpid() returns the same pid as the 1584 // launcher thread rather than a unique pid per thread. 1585 // Use gettid() if you want the old pre NPTL behaviour. 1586 1587 // if you are looking for the result of a call to getpid() that 1588 // returns a unique pid for the calling thread, then look at the 1589 // OSThread::thread_id() method in osThread_linux.hpp file 1590 1591 return (int)(_initial_pid ? _initial_pid : getpid()); 1592 } 1593 1594 // DLL functions 1595 1596 const char* os::dll_file_extension() { return ".so"; } 1597 1598 // This must be hard coded because it's the system's temporary 1599 // directory not the java application's temp directory, ala java.io.tmpdir. 1600 const char* os::get_temp_directory() { return "/tmp"; } 1601 1602 static bool file_exists(const char* filename) { 1603 struct stat statbuf; 1604 if (filename == NULL || strlen(filename) == 0) { 1605 return false; 1606 } 1607 return os::stat(filename, &statbuf) == 0; 1608 } 1609 1610 bool os::dll_build_name(char* buffer, size_t buflen, 1611 const char* pname, const char* fname) { 1612 bool retval = false; 1613 // Copied from libhpi 1614 const size_t pnamelen = pname ? strlen(pname) : 0; 1615 1616 // Return error on buffer overflow. 1617 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1618 return retval; 1619 } 1620 1621 if (pnamelen == 0) { 1622 snprintf(buffer, buflen, "lib%s.so", fname); 1623 retval = true; 1624 } else if (strchr(pname, *os::path_separator()) != NULL) { 1625 int n; 1626 char** pelements = split_path(pname, &n); 1627 if (pelements == NULL) { 1628 return false; 1629 } 1630 for (int i = 0 ; i < n ; i++) { 1631 // Really shouldn't be NULL, but check can't hurt 1632 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1633 continue; // skip the empty path values 1634 } 1635 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1636 if (file_exists(buffer)) { 1637 retval = true; 1638 break; 1639 } 1640 } 1641 // release the storage 1642 for (int i = 0 ; i < n ; i++) { 1643 if (pelements[i] != NULL) { 1644 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal); 1645 } 1646 } 1647 if (pelements != NULL) { 1648 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal); 1649 } 1650 } else { 1651 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1652 retval = true; 1653 } 1654 return retval; 1655 } 1656 1657 // check if addr is inside libjvm.so 1658 bool os::address_is_in_vm(address addr) { 1659 static address libjvm_base_addr; 1660 Dl_info dlinfo; 1661 1662 if (libjvm_base_addr == NULL) { 1663 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1664 libjvm_base_addr = (address)dlinfo.dli_fbase; 1665 } 1666 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1667 } 1668 1669 if (dladdr((void *)addr, &dlinfo) != 0) { 1670 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1671 } 1672 1673 return false; 1674 } 1675 1676 bool os::dll_address_to_function_name(address addr, char *buf, 1677 int buflen, int *offset) { 1678 // buf is not optional, but offset is optional 1679 assert(buf != NULL, "sanity check"); 1680 1681 Dl_info dlinfo; 1682 1683 if (dladdr((void*)addr, &dlinfo) != 0) { 1684 // see if we have a matching symbol 1685 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1686 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1687 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1688 } 1689 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1690 return true; 1691 } 1692 // no matching symbol so try for just file info 1693 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1694 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1695 buf, buflen, offset, dlinfo.dli_fname)) { 1696 return true; 1697 } 1698 } 1699 } 1700 1701 buf[0] = '\0'; 1702 if (offset != NULL) *offset = -1; 1703 return false; 1704 } 1705 1706 struct _address_to_library_name { 1707 address addr; // input : memory address 1708 size_t buflen; // size of fname 1709 char* fname; // output: library name 1710 address base; // library base addr 1711 }; 1712 1713 static int address_to_library_name_callback(struct dl_phdr_info *info, 1714 size_t size, void *data) { 1715 int i; 1716 bool found = false; 1717 address libbase = NULL; 1718 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1719 1720 // iterate through all loadable segments 1721 for (i = 0; i < info->dlpi_phnum; i++) { 1722 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1723 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1724 // base address of a library is the lowest address of its loaded 1725 // segments. 1726 if (libbase == NULL || libbase > segbase) { 1727 libbase = segbase; 1728 } 1729 // see if 'addr' is within current segment 1730 if (segbase <= d->addr && 1731 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1732 found = true; 1733 } 1734 } 1735 } 1736 1737 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1738 // so dll_address_to_library_name() can fall through to use dladdr() which 1739 // can figure out executable name from argv[0]. 1740 if (found && info->dlpi_name && info->dlpi_name[0]) { 1741 d->base = libbase; 1742 if (d->fname) { 1743 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1744 } 1745 return 1; 1746 } 1747 return 0; 1748 } 1749 1750 bool os::dll_address_to_library_name(address addr, char* buf, 1751 int buflen, int* offset) { 1752 // buf is not optional, but offset is optional 1753 assert(buf != NULL, "sanity check"); 1754 1755 Dl_info dlinfo; 1756 struct _address_to_library_name data; 1757 1758 // There is a bug in old glibc dladdr() implementation that it could resolve 1759 // to wrong library name if the .so file has a base address != NULL. Here 1760 // we iterate through the program headers of all loaded libraries to find 1761 // out which library 'addr' really belongs to. This workaround can be 1762 // removed once the minimum requirement for glibc is moved to 2.3.x. 1763 data.addr = addr; 1764 data.fname = buf; 1765 data.buflen = buflen; 1766 data.base = NULL; 1767 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1768 1769 if (rslt) { 1770 // buf already contains library name 1771 if (offset) *offset = addr - data.base; 1772 return true; 1773 } 1774 if (dladdr((void*)addr, &dlinfo) != 0) { 1775 if (dlinfo.dli_fname != NULL) { 1776 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1777 } 1778 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1779 *offset = addr - (address)dlinfo.dli_fbase; 1780 } 1781 return true; 1782 } 1783 1784 buf[0] = '\0'; 1785 if (offset) *offset = -1; 1786 return false; 1787 } 1788 1789 // Loads .dll/.so and 1790 // in case of error it checks if .dll/.so was built for the 1791 // same architecture as Hotspot is running on 1792 1793 1794 // Remember the stack's state. The Linux dynamic linker will change 1795 // the stack to 'executable' at most once, so we must safepoint only once. 1796 bool os::Linux::_stack_is_executable = false; 1797 1798 // VM operation that loads a library. This is necessary if stack protection 1799 // of the Java stacks can be lost during loading the library. If we 1800 // do not stop the Java threads, they can stack overflow before the stacks 1801 // are protected again. 1802 class VM_LinuxDllLoad: public VM_Operation { 1803 private: 1804 const char *_filename; 1805 char *_ebuf; 1806 int _ebuflen; 1807 void *_lib; 1808 public: 1809 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1810 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1811 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1812 void doit() { 1813 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1814 os::Linux::_stack_is_executable = true; 1815 } 1816 void* loaded_library() { return _lib; } 1817 }; 1818 1819 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1820 { 1821 void * result = NULL; 1822 bool load_attempted = false; 1823 1824 // Check whether the library to load might change execution rights 1825 // of the stack. If they are changed, the protection of the stack 1826 // guard pages will be lost. We need a safepoint to fix this. 1827 // 1828 // See Linux man page execstack(8) for more info. 1829 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1830 ElfFile ef(filename); 1831 if (!ef.specifies_noexecstack()) { 1832 if (!is_init_completed()) { 1833 os::Linux::_stack_is_executable = true; 1834 // This is OK - No Java threads have been created yet, and hence no 1835 // stack guard pages to fix. 1836 // 1837 // This should happen only when you are building JDK7 using a very 1838 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1839 // 1840 // Dynamic loader will make all stacks executable after 1841 // this function returns, and will not do that again. 1842 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1843 } else { 1844 warning("You have loaded library %s which might have disabled stack guard. " 1845 "The VM will try to fix the stack guard now.\n" 1846 "It's highly recommended that you fix the library with " 1847 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1848 filename); 1849 1850 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1851 JavaThread *jt = JavaThread::current(); 1852 if (jt->thread_state() != _thread_in_native) { 1853 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1854 // that requires ExecStack. Cannot enter safe point. Let's give up. 1855 warning("Unable to fix stack guard. Giving up."); 1856 } else { 1857 if (!LoadExecStackDllInVMThread) { 1858 // This is for the case where the DLL has an static 1859 // constructor function that executes JNI code. We cannot 1860 // load such DLLs in the VMThread. 1861 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1862 } 1863 1864 ThreadInVMfromNative tiv(jt); 1865 debug_only(VMNativeEntryWrapper vew;) 1866 1867 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1868 VMThread::execute(&op); 1869 if (LoadExecStackDllInVMThread) { 1870 result = op.loaded_library(); 1871 } 1872 load_attempted = true; 1873 } 1874 } 1875 } 1876 } 1877 1878 if (!load_attempted) { 1879 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1880 } 1881 1882 if (result != NULL) { 1883 // Successful loading 1884 return result; 1885 } 1886 1887 Elf32_Ehdr elf_head; 1888 int diag_msg_max_length=ebuflen-strlen(ebuf); 1889 char* diag_msg_buf=ebuf+strlen(ebuf); 1890 1891 if (diag_msg_max_length==0) { 1892 // No more space in ebuf for additional diagnostics message 1893 return NULL; 1894 } 1895 1896 1897 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1898 1899 if (file_descriptor < 0) { 1900 // Can't open library, report dlerror() message 1901 return NULL; 1902 } 1903 1904 bool failed_to_read_elf_head= 1905 (sizeof(elf_head)!= 1906 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1907 1908 ::close(file_descriptor); 1909 if (failed_to_read_elf_head) { 1910 // file i/o error - report dlerror() msg 1911 return NULL; 1912 } 1913 1914 typedef struct { 1915 Elf32_Half code; // Actual value as defined in elf.h 1916 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1917 char elf_class; // 32 or 64 bit 1918 char endianess; // MSB or LSB 1919 char* name; // String representation 1920 } arch_t; 1921 1922 #ifndef EM_486 1923 #define EM_486 6 /* Intel 80486 */ 1924 #endif 1925 1926 static const arch_t arch_array[]={ 1927 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1928 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1929 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1930 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1931 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1932 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1933 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1934 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1935 #if defined(VM_LITTLE_ENDIAN) 1936 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"}, 1937 #else 1938 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1939 #endif 1940 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1941 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1942 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1943 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1944 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1945 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1946 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1947 }; 1948 1949 #if (defined IA32) 1950 static Elf32_Half running_arch_code=EM_386; 1951 #elif (defined AMD64) 1952 static Elf32_Half running_arch_code=EM_X86_64; 1953 #elif (defined IA64) 1954 static Elf32_Half running_arch_code=EM_IA_64; 1955 #elif (defined __sparc) && (defined _LP64) 1956 static Elf32_Half running_arch_code=EM_SPARCV9; 1957 #elif (defined __sparc) && (!defined _LP64) 1958 static Elf32_Half running_arch_code=EM_SPARC; 1959 #elif (defined __powerpc64__) 1960 static Elf32_Half running_arch_code=EM_PPC64; 1961 #elif (defined __powerpc__) 1962 static Elf32_Half running_arch_code=EM_PPC; 1963 #elif (defined ARM) 1964 static Elf32_Half running_arch_code=EM_ARM; 1965 #elif (defined S390) 1966 static Elf32_Half running_arch_code=EM_S390; 1967 #elif (defined ALPHA) 1968 static Elf32_Half running_arch_code=EM_ALPHA; 1969 #elif (defined MIPSEL) 1970 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1971 #elif (defined PARISC) 1972 static Elf32_Half running_arch_code=EM_PARISC; 1973 #elif (defined MIPS) 1974 static Elf32_Half running_arch_code=EM_MIPS; 1975 #elif (defined M68K) 1976 static Elf32_Half running_arch_code=EM_68K; 1977 #else 1978 #error Method os::dll_load requires that one of following is defined:\ 1979 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1980 #endif 1981 1982 // Identify compatability class for VM's architecture and library's architecture 1983 // Obtain string descriptions for architectures 1984 1985 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1986 int running_arch_index=-1; 1987 1988 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 1989 if (running_arch_code == arch_array[i].code) { 1990 running_arch_index = i; 1991 } 1992 if (lib_arch.code == arch_array[i].code) { 1993 lib_arch.compat_class = arch_array[i].compat_class; 1994 lib_arch.name = arch_array[i].name; 1995 } 1996 } 1997 1998 assert(running_arch_index != -1, 1999 "Didn't find running architecture code (running_arch_code) in arch_array"); 2000 if (running_arch_index == -1) { 2001 // Even though running architecture detection failed 2002 // we may still continue with reporting dlerror() message 2003 return NULL; 2004 } 2005 2006 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 2007 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 2008 return NULL; 2009 } 2010 2011 #ifndef S390 2012 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 2013 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 2014 return NULL; 2015 } 2016 #endif // !S390 2017 2018 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 2019 if ( lib_arch.name!=NULL ) { 2020 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2021 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 2022 lib_arch.name, arch_array[running_arch_index].name); 2023 } else { 2024 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2025 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 2026 lib_arch.code, 2027 arch_array[running_arch_index].name); 2028 } 2029 } 2030 2031 return NULL; 2032 } 2033 2034 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) { 2035 void * result = ::dlopen(filename, RTLD_LAZY); 2036 if (result == NULL) { 2037 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2038 ebuf[ebuflen-1] = '\0'; 2039 } 2040 return result; 2041 } 2042 2043 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) { 2044 void * result = NULL; 2045 if (LoadExecStackDllInVMThread) { 2046 result = dlopen_helper(filename, ebuf, ebuflen); 2047 } 2048 2049 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2050 // library that requires an executable stack, or which does not have this 2051 // stack attribute set, dlopen changes the stack attribute to executable. The 2052 // read protection of the guard pages gets lost. 2053 // 2054 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2055 // may have been queued at the same time. 2056 2057 if (!_stack_is_executable) { 2058 JavaThread *jt = Threads::first(); 2059 2060 while (jt) { 2061 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2062 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2063 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2064 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2065 warning("Attempt to reguard stack yellow zone failed."); 2066 } 2067 } 2068 jt = jt->next(); 2069 } 2070 } 2071 2072 return result; 2073 } 2074 2075 /* 2076 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2077 * chances are you might want to run the generated bits against glibc-2.0 2078 * libdl.so, so always use locking for any version of glibc. 2079 */ 2080 void* os::dll_lookup(void* handle, const char* name) { 2081 pthread_mutex_lock(&dl_mutex); 2082 void* res = dlsym(handle, name); 2083 pthread_mutex_unlock(&dl_mutex); 2084 return res; 2085 } 2086 2087 void* os::get_default_process_handle() { 2088 return (void*)::dlopen(NULL, RTLD_LAZY); 2089 } 2090 2091 static bool _print_ascii_file(const char* filename, outputStream* st) { 2092 int fd = ::open(filename, O_RDONLY); 2093 if (fd == -1) { 2094 return false; 2095 } 2096 2097 char buf[32]; 2098 int bytes; 2099 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2100 st->print_raw(buf, bytes); 2101 } 2102 2103 ::close(fd); 2104 2105 return true; 2106 } 2107 2108 void os::print_dll_info(outputStream *st) { 2109 st->print_cr("Dynamic libraries:"); 2110 2111 char fname[32]; 2112 pid_t pid = os::Linux::gettid(); 2113 2114 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2115 2116 if (!_print_ascii_file(fname, st)) { 2117 st->print("Can not get library information for pid = %d\n", pid); 2118 } 2119 } 2120 2121 void os::print_os_info_brief(outputStream* st) { 2122 os::Linux::print_distro_info(st); 2123 2124 os::Posix::print_uname_info(st); 2125 2126 os::Linux::print_libversion_info(st); 2127 2128 } 2129 2130 void os::print_os_info(outputStream* st) { 2131 st->print("OS:"); 2132 2133 os::Linux::print_distro_info(st); 2134 2135 os::Posix::print_uname_info(st); 2136 2137 // Print warning if unsafe chroot environment detected 2138 if (unsafe_chroot_detected) { 2139 st->print("WARNING!! "); 2140 st->print_cr("%s", unstable_chroot_error); 2141 } 2142 2143 os::Linux::print_libversion_info(st); 2144 2145 os::Posix::print_rlimit_info(st); 2146 2147 os::Posix::print_load_average(st); 2148 2149 os::Linux::print_full_memory_info(st); 2150 } 2151 2152 // Try to identify popular distros. 2153 // Most Linux distributions have a /etc/XXX-release file, which contains 2154 // the OS version string. Newer Linux distributions have a /etc/lsb-release 2155 // file that also contains the OS version string. Some have more than one 2156 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2157 // /etc/redhat-release.), so the order is important. 2158 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2159 // their own specific XXX-release file as well as a redhat-release file. 2160 // Because of this the XXX-release file needs to be searched for before the 2161 // redhat-release file. 2162 // Since Red Hat has a lsb-release file that is not very descriptive the 2163 // search for redhat-release needs to be before lsb-release. 2164 // Since the lsb-release file is the new standard it needs to be searched 2165 // before the older style release files. 2166 // Searching system-release (Red Hat) and os-release (other Linuxes) are a 2167 // next to last resort. The os-release file is a new standard that contains 2168 // distribution information and the system-release file seems to be an old 2169 // standard that has been replaced by the lsb-release and os-release files. 2170 // Searching for the debian_version file is the last resort. It contains 2171 // an informative string like "6.0.6" or "wheezy/sid". Because of this 2172 // "Debian " is printed before the contents of the debian_version file. 2173 void os::Linux::print_distro_info(outputStream* st) { 2174 if (!_print_ascii_file("/etc/oracle-release", st) && 2175 !_print_ascii_file("/etc/mandriva-release", st) && 2176 !_print_ascii_file("/etc/mandrake-release", st) && 2177 !_print_ascii_file("/etc/sun-release", st) && 2178 !_print_ascii_file("/etc/redhat-release", st) && 2179 !_print_ascii_file("/etc/lsb-release", st) && 2180 !_print_ascii_file("/etc/SuSE-release", st) && 2181 !_print_ascii_file("/etc/turbolinux-release", st) && 2182 !_print_ascii_file("/etc/gentoo-release", st) && 2183 !_print_ascii_file("/etc/ltib-release", st) && 2184 !_print_ascii_file("/etc/angstrom-version", st) && 2185 !_print_ascii_file("/etc/system-release", st) && 2186 !_print_ascii_file("/etc/os-release", st)) { 2187 2188 if (file_exists("/etc/debian_version")) { 2189 st->print("Debian "); 2190 _print_ascii_file("/etc/debian_version", st); 2191 } else { 2192 st->print("Linux"); 2193 } 2194 } 2195 st->cr(); 2196 } 2197 2198 void os::Linux::print_libversion_info(outputStream* st) { 2199 // libc, pthread 2200 st->print("libc:"); 2201 st->print("%s ", os::Linux::glibc_version()); 2202 st->print("%s ", os::Linux::libpthread_version()); 2203 if (os::Linux::is_LinuxThreads()) { 2204 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2205 } 2206 st->cr(); 2207 } 2208 2209 void os::Linux::print_full_memory_info(outputStream* st) { 2210 st->print("\n/proc/meminfo:\n"); 2211 _print_ascii_file("/proc/meminfo", st); 2212 st->cr(); 2213 } 2214 2215 void os::print_memory_info(outputStream* st) { 2216 2217 st->print("Memory:"); 2218 st->print(" %dk page", os::vm_page_size()>>10); 2219 2220 // values in struct sysinfo are "unsigned long" 2221 struct sysinfo si; 2222 sysinfo(&si); 2223 2224 st->print(", physical " UINT64_FORMAT "k", 2225 os::physical_memory() >> 10); 2226 st->print("(" UINT64_FORMAT "k free)", 2227 os::available_memory() >> 10); 2228 st->print(", swap " UINT64_FORMAT "k", 2229 ((jlong)si.totalswap * si.mem_unit) >> 10); 2230 st->print("(" UINT64_FORMAT "k free)", 2231 ((jlong)si.freeswap * si.mem_unit) >> 10); 2232 st->cr(); 2233 } 2234 2235 void os::pd_print_cpu_info(outputStream* st) { 2236 st->print("\n/proc/cpuinfo:\n"); 2237 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2238 st->print(" <Not Available>"); 2239 } 2240 st->cr(); 2241 } 2242 2243 void os::print_siginfo(outputStream* st, void* siginfo) { 2244 const siginfo_t* si = (const siginfo_t*)siginfo; 2245 2246 os::Posix::print_siginfo_brief(st, si); 2247 #if INCLUDE_CDS 2248 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2249 UseSharedSpaces) { 2250 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2251 if (mapinfo->is_in_shared_space(si->si_addr)) { 2252 st->print("\n\nError accessing class data sharing archive." \ 2253 " Mapped file inaccessible during execution, " \ 2254 " possible disk/network problem."); 2255 } 2256 } 2257 #endif 2258 st->cr(); 2259 } 2260 2261 2262 static void print_signal_handler(outputStream* st, int sig, 2263 char* buf, size_t buflen); 2264 2265 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2266 st->print_cr("Signal Handlers:"); 2267 print_signal_handler(st, SIGSEGV, buf, buflen); 2268 print_signal_handler(st, SIGBUS , buf, buflen); 2269 print_signal_handler(st, SIGFPE , buf, buflen); 2270 print_signal_handler(st, SIGPIPE, buf, buflen); 2271 print_signal_handler(st, SIGXFSZ, buf, buflen); 2272 print_signal_handler(st, SIGILL , buf, buflen); 2273 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2274 print_signal_handler(st, SR_signum, buf, buflen); 2275 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2276 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2277 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2278 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2279 #if defined(PPC64) 2280 print_signal_handler(st, SIGTRAP, buf, buflen); 2281 #endif 2282 } 2283 2284 static char saved_jvm_path[MAXPATHLEN] = {0}; 2285 2286 // Find the full path to the current module, libjvm.so 2287 void os::jvm_path(char *buf, jint buflen) { 2288 // Error checking. 2289 if (buflen < MAXPATHLEN) { 2290 assert(false, "must use a large-enough buffer"); 2291 buf[0] = '\0'; 2292 return; 2293 } 2294 // Lazy resolve the path to current module. 2295 if (saved_jvm_path[0] != 0) { 2296 strcpy(buf, saved_jvm_path); 2297 return; 2298 } 2299 2300 char dli_fname[MAXPATHLEN]; 2301 bool ret = dll_address_to_library_name( 2302 CAST_FROM_FN_PTR(address, os::jvm_path), 2303 dli_fname, sizeof(dli_fname), NULL); 2304 assert(ret, "cannot locate libjvm"); 2305 char *rp = NULL; 2306 if (ret && dli_fname[0] != '\0') { 2307 rp = realpath(dli_fname, buf); 2308 } 2309 if (rp == NULL) 2310 return; 2311 2312 if (Arguments::created_by_gamma_launcher()) { 2313 // Support for the gamma launcher. Typical value for buf is 2314 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at 2315 // the right place in the string, then assume we are installed in a JDK and 2316 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix 2317 // up the path so it looks like libjvm.so is installed there (append a 2318 // fake suffix hotspot/libjvm.so). 2319 const char *p = buf + strlen(buf) - 1; 2320 for (int count = 0; p > buf && count < 5; ++count) { 2321 for (--p; p > buf && *p != '/'; --p) 2322 /* empty */ ; 2323 } 2324 2325 if (strncmp(p, "/jre/lib/", 9) != 0) { 2326 // Look for JAVA_HOME in the environment. 2327 char* java_home_var = ::getenv("JAVA_HOME"); 2328 if (java_home_var != NULL && java_home_var[0] != 0) { 2329 char* jrelib_p; 2330 int len; 2331 2332 // Check the current module name "libjvm.so". 2333 p = strrchr(buf, '/'); 2334 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2335 2336 rp = realpath(java_home_var, buf); 2337 if (rp == NULL) 2338 return; 2339 2340 // determine if this is a legacy image or modules image 2341 // modules image doesn't have "jre" subdirectory 2342 len = strlen(buf); 2343 assert(len < buflen, "Ran out of buffer room"); 2344 jrelib_p = buf + len; 2345 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2346 if (0 != access(buf, F_OK)) { 2347 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2348 } 2349 2350 if (0 == access(buf, F_OK)) { 2351 // Use current module name "libjvm.so" 2352 len = strlen(buf); 2353 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2354 } else { 2355 // Go back to path of .so 2356 rp = realpath(dli_fname, buf); 2357 if (rp == NULL) 2358 return; 2359 } 2360 } 2361 } 2362 } 2363 2364 strncpy(saved_jvm_path, buf, MAXPATHLEN); 2365 } 2366 2367 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2368 // no prefix required, not even "_" 2369 } 2370 2371 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2372 // no suffix required 2373 } 2374 2375 //////////////////////////////////////////////////////////////////////////////// 2376 // sun.misc.Signal support 2377 2378 static volatile jint sigint_count = 0; 2379 2380 static void 2381 UserHandler(int sig, void *siginfo, void *context) { 2382 // 4511530 - sem_post is serialized and handled by the manager thread. When 2383 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2384 // don't want to flood the manager thread with sem_post requests. 2385 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2386 return; 2387 2388 // Ctrl-C is pressed during error reporting, likely because the error 2389 // handler fails to abort. Let VM die immediately. 2390 if (sig == SIGINT && is_error_reported()) { 2391 os::die(); 2392 } 2393 2394 os::signal_notify(sig); 2395 } 2396 2397 void* os::user_handler() { 2398 return CAST_FROM_FN_PTR(void*, UserHandler); 2399 } 2400 2401 class Semaphore : public StackObj { 2402 public: 2403 Semaphore(); 2404 ~Semaphore(); 2405 void signal(); 2406 void wait(); 2407 bool trywait(); 2408 bool timedwait(unsigned int sec, int nsec); 2409 private: 2410 sem_t _semaphore; 2411 }; 2412 2413 Semaphore::Semaphore() { 2414 sem_init(&_semaphore, 0, 0); 2415 } 2416 2417 Semaphore::~Semaphore() { 2418 sem_destroy(&_semaphore); 2419 } 2420 2421 void Semaphore::signal() { 2422 sem_post(&_semaphore); 2423 } 2424 2425 void Semaphore::wait() { 2426 sem_wait(&_semaphore); 2427 } 2428 2429 bool Semaphore::trywait() { 2430 return sem_trywait(&_semaphore) == 0; 2431 } 2432 2433 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2434 2435 struct timespec ts; 2436 // Semaphore's are always associated with CLOCK_REALTIME 2437 os::Linux::clock_gettime(CLOCK_REALTIME, &ts); 2438 // see unpackTime for discussion on overflow checking 2439 if (sec >= MAX_SECS) { 2440 ts.tv_sec += MAX_SECS; 2441 ts.tv_nsec = 0; 2442 } else { 2443 ts.tv_sec += sec; 2444 ts.tv_nsec += nsec; 2445 if (ts.tv_nsec >= NANOSECS_PER_SEC) { 2446 ts.tv_nsec -= NANOSECS_PER_SEC; 2447 ++ts.tv_sec; // note: this must be <= max_secs 2448 } 2449 } 2450 2451 while (1) { 2452 int result = sem_timedwait(&_semaphore, &ts); 2453 if (result == 0) { 2454 return true; 2455 } else if (errno == EINTR) { 2456 continue; 2457 } else if (errno == ETIMEDOUT) { 2458 return false; 2459 } else { 2460 return false; 2461 } 2462 } 2463 } 2464 2465 extern "C" { 2466 typedef void (*sa_handler_t)(int); 2467 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2468 } 2469 2470 void* os::signal(int signal_number, void* handler) { 2471 struct sigaction sigAct, oldSigAct; 2472 2473 sigfillset(&(sigAct.sa_mask)); 2474 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2475 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2476 2477 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2478 // -1 means registration failed 2479 return (void *)-1; 2480 } 2481 2482 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2483 } 2484 2485 void os::signal_raise(int signal_number) { 2486 ::raise(signal_number); 2487 } 2488 2489 /* 2490 * The following code is moved from os.cpp for making this 2491 * code platform specific, which it is by its very nature. 2492 */ 2493 2494 // Will be modified when max signal is changed to be dynamic 2495 int os::sigexitnum_pd() { 2496 return NSIG; 2497 } 2498 2499 // a counter for each possible signal value 2500 static volatile jint pending_signals[NSIG+1] = { 0 }; 2501 2502 // Linux(POSIX) specific hand shaking semaphore. 2503 static sem_t sig_sem; 2504 static Semaphore sr_semaphore; 2505 2506 void os::signal_init_pd() { 2507 // Initialize signal structures 2508 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2509 2510 // Initialize signal semaphore 2511 ::sem_init(&sig_sem, 0, 0); 2512 } 2513 2514 void os::signal_notify(int sig) { 2515 Atomic::inc(&pending_signals[sig]); 2516 ::sem_post(&sig_sem); 2517 } 2518 2519 static int check_pending_signals(bool wait) { 2520 Atomic::store(0, &sigint_count); 2521 for (;;) { 2522 for (int i = 0; i < NSIG + 1; i++) { 2523 jint n = pending_signals[i]; 2524 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2525 return i; 2526 } 2527 } 2528 if (!wait) { 2529 return -1; 2530 } 2531 JavaThread *thread = JavaThread::current(); 2532 ThreadBlockInVM tbivm(thread); 2533 2534 bool threadIsSuspended; 2535 do { 2536 thread->set_suspend_equivalent(); 2537 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2538 ::sem_wait(&sig_sem); 2539 2540 // were we externally suspended while we were waiting? 2541 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2542 if (threadIsSuspended) { 2543 // 2544 // The semaphore has been incremented, but while we were waiting 2545 // another thread suspended us. We don't want to continue running 2546 // while suspended because that would surprise the thread that 2547 // suspended us. 2548 // 2549 ::sem_post(&sig_sem); 2550 2551 thread->java_suspend_self(); 2552 } 2553 } while (threadIsSuspended); 2554 } 2555 } 2556 2557 int os::signal_lookup() { 2558 return check_pending_signals(false); 2559 } 2560 2561 int os::signal_wait() { 2562 return check_pending_signals(true); 2563 } 2564 2565 //////////////////////////////////////////////////////////////////////////////// 2566 // Virtual Memory 2567 2568 int os::vm_page_size() { 2569 // Seems redundant as all get out 2570 assert(os::Linux::page_size() != -1, "must call os::init"); 2571 return os::Linux::page_size(); 2572 } 2573 2574 // Solaris allocates memory by pages. 2575 int os::vm_allocation_granularity() { 2576 assert(os::Linux::page_size() != -1, "must call os::init"); 2577 return os::Linux::page_size(); 2578 } 2579 2580 // Rationale behind this function: 2581 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2582 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2583 // samples for JITted code. Here we create private executable mapping over the code cache 2584 // and then we can use standard (well, almost, as mapping can change) way to provide 2585 // info for the reporting script by storing timestamp and location of symbol 2586 void linux_wrap_code(char* base, size_t size) { 2587 static volatile jint cnt = 0; 2588 2589 if (!UseOprofile) { 2590 return; 2591 } 2592 2593 char buf[PATH_MAX+1]; 2594 int num = Atomic::add(1, &cnt); 2595 2596 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2597 os::get_temp_directory(), os::current_process_id(), num); 2598 unlink(buf); 2599 2600 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2601 2602 if (fd != -1) { 2603 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2604 if (rv != (off_t)-1) { 2605 if (::write(fd, "", 1) == 1) { 2606 mmap(base, size, 2607 PROT_READ|PROT_WRITE|PROT_EXEC, 2608 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2609 } 2610 } 2611 ::close(fd); 2612 unlink(buf); 2613 } 2614 } 2615 2616 static bool recoverable_mmap_error(int err) { 2617 // See if the error is one we can let the caller handle. This 2618 // list of errno values comes from JBS-6843484. I can't find a 2619 // Linux man page that documents this specific set of errno 2620 // values so while this list currently matches Solaris, it may 2621 // change as we gain experience with this failure mode. 2622 switch (err) { 2623 case EBADF: 2624 case EINVAL: 2625 case ENOTSUP: 2626 // let the caller deal with these errors 2627 return true; 2628 2629 default: 2630 // Any remaining errors on this OS can cause our reserved mapping 2631 // to be lost. That can cause confusion where different data 2632 // structures think they have the same memory mapped. The worst 2633 // scenario is if both the VM and a library think they have the 2634 // same memory mapped. 2635 return false; 2636 } 2637 } 2638 2639 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2640 int err) { 2641 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2642 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2643 strerror(err), err); 2644 } 2645 2646 static void warn_fail_commit_memory(char* addr, size_t size, 2647 size_t alignment_hint, bool exec, 2648 int err) { 2649 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2650 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2651 alignment_hint, exec, strerror(err), err); 2652 } 2653 2654 // NOTE: Linux kernel does not really reserve the pages for us. 2655 // All it does is to check if there are enough free pages 2656 // left at the time of mmap(). This could be a potential 2657 // problem. 2658 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2659 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2660 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2661 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2662 if (res != (uintptr_t) MAP_FAILED) { 2663 if (UseNUMAInterleaving) { 2664 numa_make_global(addr, size); 2665 } 2666 return 0; 2667 } 2668 2669 int err = errno; // save errno from mmap() call above 2670 2671 if (!recoverable_mmap_error(err)) { 2672 warn_fail_commit_memory(addr, size, exec, err); 2673 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2674 } 2675 2676 return err; 2677 } 2678 2679 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2680 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2681 } 2682 2683 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2684 const char* mesg) { 2685 assert(mesg != NULL, "mesg must be specified"); 2686 int err = os::Linux::commit_memory_impl(addr, size, exec); 2687 if (err != 0) { 2688 // the caller wants all commit errors to exit with the specified mesg: 2689 warn_fail_commit_memory(addr, size, exec, err); 2690 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2691 } 2692 } 2693 2694 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2695 #ifndef MAP_HUGETLB 2696 #define MAP_HUGETLB 0x40000 2697 #endif 2698 2699 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2700 #ifndef MADV_HUGEPAGE 2701 #define MADV_HUGEPAGE 14 2702 #endif 2703 2704 int os::Linux::commit_memory_impl(char* addr, size_t size, 2705 size_t alignment_hint, bool exec) { 2706 int err = os::Linux::commit_memory_impl(addr, size, exec); 2707 if (err == 0) { 2708 realign_memory(addr, size, alignment_hint); 2709 } 2710 return err; 2711 } 2712 2713 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2714 bool exec) { 2715 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2716 } 2717 2718 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2719 size_t alignment_hint, bool exec, 2720 const char* mesg) { 2721 assert(mesg != NULL, "mesg must be specified"); 2722 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2723 if (err != 0) { 2724 // the caller wants all commit errors to exit with the specified mesg: 2725 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2726 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2727 } 2728 } 2729 2730 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2731 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2732 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2733 // be supported or the memory may already be backed by huge pages. 2734 ::madvise(addr, bytes, MADV_HUGEPAGE); 2735 } 2736 } 2737 2738 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2739 // This method works by doing an mmap over an existing mmaping and effectively discarding 2740 // the existing pages. However it won't work for SHM-based large pages that cannot be 2741 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2742 // small pages on top of the SHM segment. This method always works for small pages, so we 2743 // allow that in any case. 2744 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2745 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2746 } 2747 } 2748 2749 void os::numa_make_global(char *addr, size_t bytes) { 2750 Linux::numa_interleave_memory(addr, bytes); 2751 } 2752 2753 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2754 // bind policy to MPOL_PREFERRED for the current thread. 2755 #define USE_MPOL_PREFERRED 0 2756 2757 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2758 // To make NUMA and large pages more robust when both enabled, we need to ease 2759 // the requirements on where the memory should be allocated. MPOL_BIND is the 2760 // default policy and it will force memory to be allocated on the specified 2761 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2762 // the specified node, but will not force it. Using this policy will prevent 2763 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2764 // free large pages. 2765 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2766 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2767 } 2768 2769 bool os::numa_topology_changed() { return false; } 2770 2771 size_t os::numa_get_groups_num() { 2772 int max_node = Linux::numa_max_node(); 2773 return max_node > 0 ? max_node + 1 : 1; 2774 } 2775 2776 int os::numa_get_group_id() { 2777 int cpu_id = Linux::sched_getcpu(); 2778 if (cpu_id != -1) { 2779 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2780 if (lgrp_id != -1) { 2781 return lgrp_id; 2782 } 2783 } 2784 return 0; 2785 } 2786 2787 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2788 for (size_t i = 0; i < size; i++) { 2789 ids[i] = i; 2790 } 2791 return size; 2792 } 2793 2794 bool os::get_page_info(char *start, page_info* info) { 2795 return false; 2796 } 2797 2798 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2799 return end; 2800 } 2801 2802 2803 int os::Linux::sched_getcpu_syscall(void) { 2804 unsigned int cpu; 2805 int retval = -1; 2806 2807 #if defined(IA32) 2808 # ifndef SYS_getcpu 2809 # define SYS_getcpu 318 2810 # endif 2811 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2812 #elif defined(AMD64) 2813 // Unfortunately we have to bring all these macros here from vsyscall.h 2814 // to be able to compile on old linuxes. 2815 # define __NR_vgetcpu 2 2816 # define VSYSCALL_START (-10UL << 20) 2817 # define VSYSCALL_SIZE 1024 2818 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2819 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2820 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2821 retval = vgetcpu(&cpu, NULL, NULL); 2822 #endif 2823 2824 return (retval == -1) ? retval : cpu; 2825 } 2826 2827 // Something to do with the numa-aware allocator needs these symbols 2828 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2829 extern "C" JNIEXPORT void numa_error(char *where) { } 2830 extern "C" JNIEXPORT int fork1() { return fork(); } 2831 2832 2833 // If we are running with libnuma version > 2, then we should 2834 // be trying to use symbols with versions 1.1 2835 // If we are running with earlier version, which did not have symbol versions, 2836 // we should use the base version. 2837 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2838 void *f = dlvsym(handle, name, "libnuma_1.1"); 2839 if (f == NULL) { 2840 f = dlsym(handle, name); 2841 } 2842 return f; 2843 } 2844 2845 bool os::Linux::libnuma_init() { 2846 // sched_getcpu() should be in libc. 2847 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2848 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2849 2850 // If it's not, try a direct syscall. 2851 if (sched_getcpu() == -1) 2852 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall)); 2853 2854 if (sched_getcpu() != -1) { // Does it work? 2855 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2856 if (handle != NULL) { 2857 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2858 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2859 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2860 libnuma_dlsym(handle, "numa_max_node"))); 2861 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2862 libnuma_dlsym(handle, "numa_available"))); 2863 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2864 libnuma_dlsym(handle, "numa_tonode_memory"))); 2865 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2866 libnuma_dlsym(handle, "numa_interleave_memory"))); 2867 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2868 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2869 2870 2871 if (numa_available() != -1) { 2872 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2873 // Create a cpu -> node mapping 2874 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2875 rebuild_cpu_to_node_map(); 2876 return true; 2877 } 2878 } 2879 } 2880 return false; 2881 } 2882 2883 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2884 // The table is later used in get_node_by_cpu(). 2885 void os::Linux::rebuild_cpu_to_node_map() { 2886 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2887 // in libnuma (possible values are starting from 16, 2888 // and continuing up with every other power of 2, but less 2889 // than the maximum number of CPUs supported by kernel), and 2890 // is a subject to change (in libnuma version 2 the requirements 2891 // are more reasonable) we'll just hardcode the number they use 2892 // in the library. 2893 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2894 2895 size_t cpu_num = os::active_processor_count(); 2896 size_t cpu_map_size = NCPUS / BitsPerCLong; 2897 size_t cpu_map_valid_size = 2898 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2899 2900 cpu_to_node()->clear(); 2901 cpu_to_node()->at_grow(cpu_num - 1); 2902 size_t node_num = numa_get_groups_num(); 2903 2904 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2905 for (size_t i = 0; i < node_num; i++) { 2906 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2907 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2908 if (cpu_map[j] != 0) { 2909 for (size_t k = 0; k < BitsPerCLong; k++) { 2910 if (cpu_map[j] & (1UL << k)) { 2911 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2912 } 2913 } 2914 } 2915 } 2916 } 2917 } 2918 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal); 2919 } 2920 2921 int os::Linux::get_node_by_cpu(int cpu_id) { 2922 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2923 return cpu_to_node()->at(cpu_id); 2924 } 2925 return -1; 2926 } 2927 2928 GrowableArray<int>* os::Linux::_cpu_to_node; 2929 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2930 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2931 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2932 os::Linux::numa_available_func_t os::Linux::_numa_available; 2933 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2934 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2935 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2936 unsigned long* os::Linux::_numa_all_nodes; 2937 2938 bool os::pd_uncommit_memory(char* addr, size_t size) { 2939 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2940 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2941 return res != (uintptr_t) MAP_FAILED; 2942 } 2943 2944 static 2945 address get_stack_commited_bottom(address bottom, size_t size) { 2946 address nbot = bottom; 2947 address ntop = bottom + size; 2948 2949 size_t page_sz = os::vm_page_size(); 2950 unsigned pages = size / page_sz; 2951 2952 unsigned char vec[1]; 2953 unsigned imin = 1, imax = pages + 1, imid; 2954 int mincore_return_value = 0; 2955 2956 assert(imin <= imax, "Unexpected page size"); 2957 2958 while (imin < imax) { 2959 imid = (imax + imin) / 2; 2960 nbot = ntop - (imid * page_sz); 2961 2962 // Use a trick with mincore to check whether the page is mapped or not. 2963 // mincore sets vec to 1 if page resides in memory and to 0 if page 2964 // is swapped output but if page we are asking for is unmapped 2965 // it returns -1,ENOMEM 2966 mincore_return_value = mincore(nbot, page_sz, vec); 2967 2968 if (mincore_return_value == -1) { 2969 // Page is not mapped go up 2970 // to find first mapped page 2971 if (errno != EAGAIN) { 2972 assert(errno == ENOMEM, "Unexpected mincore errno"); 2973 imax = imid; 2974 } 2975 } else { 2976 // Page is mapped go down 2977 // to find first not mapped page 2978 imin = imid + 1; 2979 } 2980 } 2981 2982 nbot = nbot + page_sz; 2983 2984 // Adjust stack bottom one page up if last checked page is not mapped 2985 if (mincore_return_value == -1) { 2986 nbot = nbot + page_sz; 2987 } 2988 2989 return nbot; 2990 } 2991 2992 2993 // Linux uses a growable mapping for the stack, and if the mapping for 2994 // the stack guard pages is not removed when we detach a thread the 2995 // stack cannot grow beyond the pages where the stack guard was 2996 // mapped. If at some point later in the process the stack expands to 2997 // that point, the Linux kernel cannot expand the stack any further 2998 // because the guard pages are in the way, and a segfault occurs. 2999 // 3000 // However, it's essential not to split the stack region by unmapping 3001 // a region (leaving a hole) that's already part of the stack mapping, 3002 // so if the stack mapping has already grown beyond the guard pages at 3003 // the time we create them, we have to truncate the stack mapping. 3004 // So, we need to know the extent of the stack mapping when 3005 // create_stack_guard_pages() is called. 3006 3007 // We only need this for stacks that are growable: at the time of 3008 // writing thread stacks don't use growable mappings (i.e. those 3009 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 3010 // only applies to the main thread. 3011 3012 // If the (growable) stack mapping already extends beyond the point 3013 // where we're going to put our guard pages, truncate the mapping at 3014 // that point by munmap()ping it. This ensures that when we later 3015 // munmap() the guard pages we don't leave a hole in the stack 3016 // mapping. This only affects the main/initial thread 3017 3018 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3019 3020 if (os::Linux::is_initial_thread()) { 3021 // As we manually grow stack up to bottom inside create_attached_thread(), 3022 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3023 // we don't need to do anything special. 3024 // Check it first, before calling heavy function. 3025 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3026 unsigned char vec[1]; 3027 3028 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3029 // Fallback to slow path on all errors, including EAGAIN 3030 stack_extent = (uintptr_t) get_stack_commited_bottom( 3031 os::Linux::initial_thread_stack_bottom(), 3032 (size_t)addr - stack_extent); 3033 } 3034 3035 if (stack_extent < (uintptr_t)addr) { 3036 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3037 } 3038 } 3039 3040 return os::commit_memory(addr, size, !ExecMem); 3041 } 3042 3043 // If this is a growable mapping, remove the guard pages entirely by 3044 // munmap()ping them. If not, just call uncommit_memory(). This only 3045 // affects the main/initial thread, but guard against future OS changes 3046 // It's safe to always unmap guard pages for initial thread because we 3047 // always place it right after end of the mapped region 3048 3049 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3050 uintptr_t stack_extent, stack_base; 3051 3052 if (os::Linux::is_initial_thread()) { 3053 return ::munmap(addr, size) == 0; 3054 } 3055 3056 return os::uncommit_memory(addr, size); 3057 } 3058 3059 static address _highest_vm_reserved_address = NULL; 3060 3061 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3062 // at 'requested_addr'. If there are existing memory mappings at the same 3063 // location, however, they will be overwritten. If 'fixed' is false, 3064 // 'requested_addr' is only treated as a hint, the return value may or 3065 // may not start from the requested address. Unlike Linux mmap(), this 3066 // function returns NULL to indicate failure. 3067 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3068 char * addr; 3069 int flags; 3070 3071 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3072 if (fixed) { 3073 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3074 flags |= MAP_FIXED; 3075 } 3076 3077 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3078 // touch an uncommitted page. Otherwise, the read/write might 3079 // succeed if we have enough swap space to back the physical page. 3080 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3081 flags, -1, 0); 3082 3083 if (addr != MAP_FAILED) { 3084 // anon_mmap() should only get called during VM initialization, 3085 // don't need lock (actually we can skip locking even it can be called 3086 // from multiple threads, because _highest_vm_reserved_address is just a 3087 // hint about the upper limit of non-stack memory regions.) 3088 if ((address)addr + bytes > _highest_vm_reserved_address) { 3089 _highest_vm_reserved_address = (address)addr + bytes; 3090 } 3091 } 3092 3093 return addr == MAP_FAILED ? NULL : addr; 3094 } 3095 3096 // Don't update _highest_vm_reserved_address, because there might be memory 3097 // regions above addr + size. If so, releasing a memory region only creates 3098 // a hole in the address space, it doesn't help prevent heap-stack collision. 3099 // 3100 static int anon_munmap(char * addr, size_t size) { 3101 return ::munmap(addr, size) == 0; 3102 } 3103 3104 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3105 size_t alignment_hint) { 3106 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3107 } 3108 3109 bool os::pd_release_memory(char* addr, size_t size) { 3110 return anon_munmap(addr, size); 3111 } 3112 3113 static address highest_vm_reserved_address() { 3114 return _highest_vm_reserved_address; 3115 } 3116 3117 static bool linux_mprotect(char* addr, size_t size, int prot) { 3118 // Linux wants the mprotect address argument to be page aligned. 3119 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3120 3121 // According to SUSv3, mprotect() should only be used with mappings 3122 // established by mmap(), and mmap() always maps whole pages. Unaligned 3123 // 'addr' likely indicates problem in the VM (e.g. trying to change 3124 // protection of malloc'ed or statically allocated memory). Check the 3125 // caller if you hit this assert. 3126 assert(addr == bottom, "sanity check"); 3127 3128 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3129 return ::mprotect(bottom, size, prot) == 0; 3130 } 3131 3132 // Set protections specified 3133 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3134 bool is_committed) { 3135 unsigned int p = 0; 3136 switch (prot) { 3137 case MEM_PROT_NONE: p = PROT_NONE; break; 3138 case MEM_PROT_READ: p = PROT_READ; break; 3139 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3140 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3141 default: 3142 ShouldNotReachHere(); 3143 } 3144 // is_committed is unused. 3145 return linux_mprotect(addr, bytes, p); 3146 } 3147 3148 bool os::guard_memory(char* addr, size_t size) { 3149 return linux_mprotect(addr, size, PROT_NONE); 3150 } 3151 3152 bool os::unguard_memory(char* addr, size_t size) { 3153 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3154 } 3155 3156 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) { 3157 bool result = false; 3158 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3159 MAP_ANONYMOUS|MAP_PRIVATE, 3160 -1, 0); 3161 if (p != MAP_FAILED) { 3162 void *aligned_p = align_ptr_up(p, page_size); 3163 3164 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3165 3166 munmap(p, page_size * 2); 3167 } 3168 3169 if (warn && !result) { 3170 warning("TransparentHugePages is not supported by the operating system."); 3171 } 3172 3173 return result; 3174 } 3175 3176 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3177 bool result = false; 3178 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3179 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3180 -1, 0); 3181 3182 if (p != MAP_FAILED) { 3183 // We don't know if this really is a huge page or not. 3184 FILE *fp = fopen("/proc/self/maps", "r"); 3185 if (fp) { 3186 while (!feof(fp)) { 3187 char chars[257]; 3188 long x = 0; 3189 if (fgets(chars, sizeof(chars), fp)) { 3190 if (sscanf(chars, "%lx-%*x", &x) == 1 3191 && x == (long)p) { 3192 if (strstr (chars, "hugepage")) { 3193 result = true; 3194 break; 3195 } 3196 } 3197 } 3198 } 3199 fclose(fp); 3200 } 3201 munmap(p, page_size); 3202 } 3203 3204 if (warn && !result) { 3205 warning("HugeTLBFS is not supported by the operating system."); 3206 } 3207 3208 return result; 3209 } 3210 3211 /* 3212 * Set the coredump_filter bits to include largepages in core dump (bit 6) 3213 * 3214 * From the coredump_filter documentation: 3215 * 3216 * - (bit 0) anonymous private memory 3217 * - (bit 1) anonymous shared memory 3218 * - (bit 2) file-backed private memory 3219 * - (bit 3) file-backed shared memory 3220 * - (bit 4) ELF header pages in file-backed private memory areas (it is 3221 * effective only if the bit 2 is cleared) 3222 * - (bit 5) hugetlb private memory 3223 * - (bit 6) hugetlb shared memory 3224 */ 3225 static void set_coredump_filter(void) { 3226 FILE *f; 3227 long cdm; 3228 3229 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3230 return; 3231 } 3232 3233 if (fscanf(f, "%lx", &cdm) != 1) { 3234 fclose(f); 3235 return; 3236 } 3237 3238 rewind(f); 3239 3240 if ((cdm & LARGEPAGES_BIT) == 0) { 3241 cdm |= LARGEPAGES_BIT; 3242 fprintf(f, "%#lx", cdm); 3243 } 3244 3245 fclose(f); 3246 } 3247 3248 // Large page support 3249 3250 static size_t _large_page_size = 0; 3251 3252 size_t os::Linux::find_large_page_size() { 3253 size_t large_page_size = 0; 3254 3255 // large_page_size on Linux is used to round up heap size. x86 uses either 3256 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3257 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3258 // page as large as 256M. 3259 // 3260 // Here we try to figure out page size by parsing /proc/meminfo and looking 3261 // for a line with the following format: 3262 // Hugepagesize: 2048 kB 3263 // 3264 // If we can't determine the value (e.g. /proc is not mounted, or the text 3265 // format has been changed), we'll use the largest page size supported by 3266 // the processor. 3267 3268 #ifndef ZERO 3269 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3270 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3271 #endif // ZERO 3272 3273 FILE *fp = fopen("/proc/meminfo", "r"); 3274 if (fp) { 3275 while (!feof(fp)) { 3276 int x = 0; 3277 char buf[16]; 3278 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3279 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3280 large_page_size = x * K; 3281 break; 3282 } 3283 } else { 3284 // skip to next line 3285 for (;;) { 3286 int ch = fgetc(fp); 3287 if (ch == EOF || ch == (int)'\n') break; 3288 } 3289 } 3290 } 3291 fclose(fp); 3292 } 3293 3294 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3295 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3296 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3297 proper_unit_for_byte_size(large_page_size)); 3298 } 3299 3300 return large_page_size; 3301 } 3302 3303 size_t os::Linux::setup_large_page_size() { 3304 _large_page_size = Linux::find_large_page_size(); 3305 const size_t default_page_size = (size_t)Linux::page_size(); 3306 if (_large_page_size > default_page_size) { 3307 _page_sizes[0] = _large_page_size; 3308 _page_sizes[1] = default_page_size; 3309 _page_sizes[2] = 0; 3310 } 3311 3312 return _large_page_size; 3313 } 3314 3315 bool os::Linux::setup_large_page_type(size_t page_size) { 3316 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3317 FLAG_IS_DEFAULT(UseSHM) && 3318 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3319 3320 // The type of large pages has not been specified by the user. 3321 3322 // Try UseHugeTLBFS and then UseSHM. 3323 UseHugeTLBFS = UseSHM = true; 3324 3325 // Don't try UseTransparentHugePages since there are known 3326 // performance issues with it turned on. This might change in the future. 3327 UseTransparentHugePages = false; 3328 } 3329 3330 if (UseTransparentHugePages) { 3331 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3332 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3333 UseHugeTLBFS = false; 3334 UseSHM = false; 3335 return true; 3336 } 3337 UseTransparentHugePages = false; 3338 } 3339 3340 if (UseHugeTLBFS) { 3341 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3342 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3343 UseSHM = false; 3344 return true; 3345 } 3346 UseHugeTLBFS = false; 3347 } 3348 3349 return UseSHM; 3350 } 3351 3352 void os::large_page_init() { 3353 if (!UseLargePages && 3354 !UseTransparentHugePages && 3355 !UseHugeTLBFS && 3356 !UseSHM) { 3357 // Not using large pages. 3358 return; 3359 } 3360 3361 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3362 // The user explicitly turned off large pages. 3363 // Ignore the rest of the large pages flags. 3364 UseTransparentHugePages = false; 3365 UseHugeTLBFS = false; 3366 UseSHM = false; 3367 return; 3368 } 3369 3370 size_t large_page_size = Linux::setup_large_page_size(); 3371 UseLargePages = Linux::setup_large_page_type(large_page_size); 3372 3373 set_coredump_filter(); 3374 } 3375 3376 #ifndef SHM_HUGETLB 3377 #define SHM_HUGETLB 04000 3378 #endif 3379 3380 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3381 // "exec" is passed in but not used. Creating the shared image for 3382 // the code cache doesn't have an SHM_X executable permission to check. 3383 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3384 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3385 3386 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3387 return NULL; // Fallback to small pages. 3388 } 3389 3390 key_t key = IPC_PRIVATE; 3391 char *addr; 3392 3393 bool warn_on_failure = UseLargePages && 3394 (!FLAG_IS_DEFAULT(UseLargePages) || 3395 !FLAG_IS_DEFAULT(UseSHM) || 3396 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 3397 ); 3398 char msg[128]; 3399 3400 // Create a large shared memory region to attach to based on size. 3401 // Currently, size is the total size of the heap 3402 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3403 if (shmid == -1) { 3404 // Possible reasons for shmget failure: 3405 // 1. shmmax is too small for Java heap. 3406 // > check shmmax value: cat /proc/sys/kernel/shmmax 3407 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3408 // 2. not enough large page memory. 3409 // > check available large pages: cat /proc/meminfo 3410 // > increase amount of large pages: 3411 // echo new_value > /proc/sys/vm/nr_hugepages 3412 // Note 1: different Linux may use different name for this property, 3413 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3414 // Note 2: it's possible there's enough physical memory available but 3415 // they are so fragmented after a long run that they can't 3416 // coalesce into large pages. Try to reserve large pages when 3417 // the system is still "fresh". 3418 if (warn_on_failure) { 3419 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3420 warning("%s", msg); 3421 } 3422 return NULL; 3423 } 3424 3425 // attach to the region 3426 addr = (char*)shmat(shmid, req_addr, 0); 3427 int err = errno; 3428 3429 // Remove shmid. If shmat() is successful, the actual shared memory segment 3430 // will be deleted when it's detached by shmdt() or when the process 3431 // terminates. If shmat() is not successful this will remove the shared 3432 // segment immediately. 3433 shmctl(shmid, IPC_RMID, NULL); 3434 3435 if ((intptr_t)addr == -1) { 3436 if (warn_on_failure) { 3437 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3438 warning("%s", msg); 3439 } 3440 return NULL; 3441 } 3442 3443 return addr; 3444 } 3445 3446 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) { 3447 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3448 3449 bool warn_on_failure = UseLargePages && 3450 (!FLAG_IS_DEFAULT(UseLargePages) || 3451 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3452 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3453 3454 if (warn_on_failure) { 3455 char msg[128]; 3456 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3457 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3458 warning("%s", msg); 3459 } 3460 } 3461 3462 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) { 3463 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3464 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3465 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3466 3467 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3468 char* addr = (char*)::mmap(req_addr, bytes, prot, 3469 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3470 -1, 0); 3471 3472 if (addr == MAP_FAILED) { 3473 warn_on_large_pages_failure(req_addr, bytes, errno); 3474 return NULL; 3475 } 3476 3477 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3478 3479 return addr; 3480 } 3481 3482 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3483 size_t large_page_size = os::large_page_size(); 3484 3485 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3486 3487 // Allocate small pages. 3488 3489 char* start; 3490 if (req_addr != NULL) { 3491 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3492 assert(is_size_aligned(bytes, alignment), "Must be"); 3493 start = os::reserve_memory(bytes, req_addr); 3494 assert(start == NULL || start == req_addr, "Must be"); 3495 } else { 3496 start = os::reserve_memory_aligned(bytes, alignment); 3497 } 3498 3499 if (start == NULL) { 3500 return NULL; 3501 } 3502 3503 assert(is_ptr_aligned(start, alignment), "Must be"); 3504 3505 if (MemTracker::tracking_level() > NMT_minimal) { 3506 // os::reserve_memory_special will record this memory area. 3507 // Need to release it here to prevent overlapping reservations. 3508 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3509 tkr.record((address)start, bytes); 3510 } 3511 3512 char* end = start + bytes; 3513 3514 // Find the regions of the allocated chunk that can be promoted to large pages. 3515 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3516 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3517 3518 size_t lp_bytes = lp_end - lp_start; 3519 3520 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3521 3522 if (lp_bytes == 0) { 3523 // The mapped region doesn't even span the start and the end of a large page. 3524 // Fall back to allocate a non-special area. 3525 ::munmap(start, end - start); 3526 return NULL; 3527 } 3528 3529 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3530 3531 3532 void* result; 3533 3534 if (start != lp_start) { 3535 result = ::mmap(start, lp_start - start, prot, 3536 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3537 -1, 0); 3538 if (result == MAP_FAILED) { 3539 ::munmap(lp_start, end - lp_start); 3540 return NULL; 3541 } 3542 } 3543 3544 result = ::mmap(lp_start, lp_bytes, prot, 3545 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3546 -1, 0); 3547 if (result == MAP_FAILED) { 3548 warn_on_large_pages_failure(req_addr, bytes, errno); 3549 // If the mmap above fails, the large pages region will be unmapped and we 3550 // have regions before and after with small pages. Release these regions. 3551 // 3552 // | mapped | unmapped | mapped | 3553 // ^ ^ ^ ^ 3554 // start lp_start lp_end end 3555 // 3556 ::munmap(start, lp_start - start); 3557 ::munmap(lp_end, end - lp_end); 3558 return NULL; 3559 } 3560 3561 if (lp_end != end) { 3562 result = ::mmap(lp_end, end - lp_end, prot, 3563 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3564 -1, 0); 3565 if (result == MAP_FAILED) { 3566 ::munmap(start, lp_end - start); 3567 return NULL; 3568 } 3569 } 3570 3571 return start; 3572 } 3573 3574 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3575 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3576 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3577 assert(is_power_of_2(alignment), "Must be"); 3578 assert(is_power_of_2(os::large_page_size()), "Must be"); 3579 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3580 3581 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3582 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3583 } else { 3584 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3585 } 3586 } 3587 3588 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3589 assert(UseLargePages, "only for large pages"); 3590 3591 char* addr; 3592 if (UseSHM) { 3593 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3594 } else { 3595 assert(UseHugeTLBFS, "must be"); 3596 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3597 } 3598 3599 if (addr != NULL) { 3600 if (UseNUMAInterleaving) { 3601 numa_make_global(addr, bytes); 3602 } 3603 3604 // The memory is committed 3605 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC); 3606 } 3607 3608 return addr; 3609 } 3610 3611 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3612 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3613 return shmdt(base) == 0; 3614 } 3615 3616 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3617 return pd_release_memory(base, bytes); 3618 } 3619 3620 bool os::release_memory_special(char* base, size_t bytes) { 3621 bool res; 3622 if (MemTracker::tracking_level() > NMT_minimal) { 3623 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3624 res = os::Linux::release_memory_special_impl(base, bytes); 3625 if (res) { 3626 tkr.record((address)base, bytes); 3627 } 3628 3629 } else { 3630 res = os::Linux::release_memory_special_impl(base, bytes); 3631 } 3632 return res; 3633 } 3634 3635 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) { 3636 assert(UseLargePages, "only for large pages"); 3637 bool res; 3638 3639 if (UseSHM) { 3640 res = os::Linux::release_memory_special_shm(base, bytes); 3641 } else { 3642 assert(UseHugeTLBFS, "must be"); 3643 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3644 } 3645 return res; 3646 } 3647 3648 size_t os::large_page_size() { 3649 return _large_page_size; 3650 } 3651 3652 // With SysV SHM the entire memory region must be allocated as shared 3653 // memory. 3654 // HugeTLBFS allows application to commit large page memory on demand. 3655 // However, when committing memory with HugeTLBFS fails, the region 3656 // that was supposed to be committed will lose the old reservation 3657 // and allow other threads to steal that memory region. Because of this 3658 // behavior we can't commit HugeTLBFS memory. 3659 bool os::can_commit_large_page_memory() { 3660 return UseTransparentHugePages; 3661 } 3662 3663 bool os::can_execute_large_page_memory() { 3664 return UseTransparentHugePages || UseHugeTLBFS; 3665 } 3666 3667 // Reserve memory at an arbitrary address, only if that area is 3668 // available (and not reserved for something else). 3669 3670 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3671 const int max_tries = 10; 3672 char* base[max_tries]; 3673 size_t size[max_tries]; 3674 const size_t gap = 0x000000; 3675 3676 // Assert only that the size is a multiple of the page size, since 3677 // that's all that mmap requires, and since that's all we really know 3678 // about at this low abstraction level. If we need higher alignment, 3679 // we can either pass an alignment to this method or verify alignment 3680 // in one of the methods further up the call chain. See bug 5044738. 3681 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3682 3683 // Repeatedly allocate blocks until the block is allocated at the 3684 // right spot. Give up after max_tries. Note that reserve_memory() will 3685 // automatically update _highest_vm_reserved_address if the call is 3686 // successful. The variable tracks the highest memory address every reserved 3687 // by JVM. It is used to detect heap-stack collision if running with 3688 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3689 // space than needed, it could confuse the collision detecting code. To 3690 // solve the problem, save current _highest_vm_reserved_address and 3691 // calculate the correct value before return. 3692 address old_highest = _highest_vm_reserved_address; 3693 3694 // Linux mmap allows caller to pass an address as hint; give it a try first, 3695 // if kernel honors the hint then we can return immediately. 3696 char * addr = anon_mmap(requested_addr, bytes, false); 3697 if (addr == requested_addr) { 3698 return requested_addr; 3699 } 3700 3701 if (addr != NULL) { 3702 // mmap() is successful but it fails to reserve at the requested address 3703 anon_munmap(addr, bytes); 3704 } 3705 3706 int i; 3707 for (i = 0; i < max_tries; ++i) { 3708 base[i] = reserve_memory(bytes); 3709 3710 if (base[i] != NULL) { 3711 // Is this the block we wanted? 3712 if (base[i] == requested_addr) { 3713 size[i] = bytes; 3714 break; 3715 } 3716 3717 // Does this overlap the block we wanted? Give back the overlapped 3718 // parts and try again. 3719 3720 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3721 if (top_overlap >= 0 && top_overlap < bytes) { 3722 unmap_memory(base[i], top_overlap); 3723 base[i] += top_overlap; 3724 size[i] = bytes - top_overlap; 3725 } else { 3726 size_t bottom_overlap = base[i] + bytes - requested_addr; 3727 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3728 unmap_memory(requested_addr, bottom_overlap); 3729 size[i] = bytes - bottom_overlap; 3730 } else { 3731 size[i] = bytes; 3732 } 3733 } 3734 } 3735 } 3736 3737 // Give back the unused reserved pieces. 3738 3739 for (int j = 0; j < i; ++j) { 3740 if (base[j] != NULL) { 3741 unmap_memory(base[j], size[j]); 3742 } 3743 } 3744 3745 if (i < max_tries) { 3746 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3747 return requested_addr; 3748 } else { 3749 _highest_vm_reserved_address = old_highest; 3750 return NULL; 3751 } 3752 } 3753 3754 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3755 return ::read(fd, buf, nBytes); 3756 } 3757 3758 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation. 3759 // Solaris uses poll(), linux uses park(). 3760 // Poll() is likely a better choice, assuming that Thread.interrupt() 3761 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with 3762 // SIGSEGV, see 4355769. 3763 3764 int os::sleep(Thread* thread, jlong millis, bool interruptible) { 3765 assert(thread == Thread::current(), "thread consistency check"); 3766 3767 ParkEvent * const slp = thread->_SleepEvent ; 3768 slp->reset() ; 3769 OrderAccess::fence() ; 3770 3771 if (interruptible) { 3772 jlong prevtime = javaTimeNanos(); 3773 3774 for (;;) { 3775 if (os::is_interrupted(thread, true)) { 3776 return OS_INTRPT; 3777 } 3778 3779 jlong newtime = javaTimeNanos(); 3780 3781 if (newtime - prevtime < 0) { 3782 // time moving backwards, should only happen if no monotonic clock 3783 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3784 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3785 } else { 3786 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3787 } 3788 3789 if(millis <= 0) { 3790 return OS_OK; 3791 } 3792 3793 prevtime = newtime; 3794 3795 { 3796 assert(thread->is_Java_thread(), "sanity check"); 3797 JavaThread *jt = (JavaThread *) thread; 3798 ThreadBlockInVM tbivm(jt); 3799 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */); 3800 3801 jt->set_suspend_equivalent(); 3802 // cleared by handle_special_suspend_equivalent_condition() or 3803 // java_suspend_self() via check_and_wait_while_suspended() 3804 3805 slp->park(millis); 3806 3807 // were we externally suspended while we were waiting? 3808 jt->check_and_wait_while_suspended(); 3809 } 3810 } 3811 } else { 3812 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 3813 jlong prevtime = javaTimeNanos(); 3814 3815 for (;;) { 3816 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on 3817 // the 1st iteration ... 3818 jlong newtime = javaTimeNanos(); 3819 3820 if (newtime - prevtime < 0) { 3821 // time moving backwards, should only happen if no monotonic clock 3822 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3823 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 3824 } else { 3825 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3826 } 3827 3828 if(millis <= 0) break ; 3829 3830 prevtime = newtime; 3831 slp->park(millis); 3832 } 3833 return OS_OK ; 3834 } 3835 } 3836 3837 // 3838 // Short sleep, direct OS call. 3839 // 3840 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee 3841 // sched_yield(2) will actually give up the CPU: 3842 // 3843 // * Alone on this pariticular CPU, keeps running. 3844 // * Before the introduction of "skip_buddy" with "compat_yield" disabled 3845 // (pre 2.6.39). 3846 // 3847 // So calling this with 0 is an alternative. 3848 // 3849 void os::naked_short_sleep(jlong ms) { 3850 struct timespec req; 3851 3852 assert(ms < 1000, "Un-interruptable sleep, short time use only"); 3853 req.tv_sec = 0; 3854 if (ms > 0) { 3855 req.tv_nsec = (ms % 1000) * 1000000; 3856 } 3857 else { 3858 req.tv_nsec = 1; 3859 } 3860 3861 nanosleep(&req, NULL); 3862 3863 return; 3864 } 3865 3866 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3867 void os::infinite_sleep() { 3868 while (true) { // sleep forever ... 3869 ::sleep(100); // ... 100 seconds at a time 3870 } 3871 } 3872 3873 // Used to convert frequent JVM_Yield() to nops 3874 bool os::dont_yield() { 3875 return DontYieldALot; 3876 } 3877 3878 void os::yield() { 3879 sched_yield(); 3880 } 3881 3882 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 3883 3884 void os::yield_all(int attempts) { 3885 // Yields to all threads, including threads with lower priorities 3886 // Threads on Linux are all with same priority. The Solaris style 3887 // os::yield_all() with nanosleep(1ms) is not necessary. 3888 sched_yield(); 3889 } 3890 3891 // Called from the tight loops to possibly influence time-sharing heuristics 3892 void os::loop_breaker(int attempts) { 3893 os::yield_all(attempts); 3894 } 3895 3896 //////////////////////////////////////////////////////////////////////////////// 3897 // thread priority support 3898 3899 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3900 // only supports dynamic priority, static priority must be zero. For real-time 3901 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3902 // However, for large multi-threaded applications, SCHED_RR is not only slower 3903 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3904 // of 5 runs - Sep 2005). 3905 // 3906 // The following code actually changes the niceness of kernel-thread/LWP. It 3907 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3908 // not the entire user process, and user level threads are 1:1 mapped to kernel 3909 // threads. It has always been the case, but could change in the future. For 3910 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3911 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3912 3913 int os::java_to_os_priority[CriticalPriority + 1] = { 3914 19, // 0 Entry should never be used 3915 3916 4, // 1 MinPriority 3917 3, // 2 3918 2, // 3 3919 3920 1, // 4 3921 0, // 5 NormPriority 3922 -1, // 6 3923 3924 -2, // 7 3925 -3, // 8 3926 -4, // 9 NearMaxPriority 3927 3928 -5, // 10 MaxPriority 3929 3930 -5 // 11 CriticalPriority 3931 }; 3932 3933 static int prio_init() { 3934 if (ThreadPriorityPolicy == 1) { 3935 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3936 // if effective uid is not root. Perhaps, a more elegant way of doing 3937 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3938 if (geteuid() != 0) { 3939 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3940 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3941 } 3942 ThreadPriorityPolicy = 0; 3943 } 3944 } 3945 if (UseCriticalJavaThreadPriority) { 3946 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3947 } 3948 return 0; 3949 } 3950 3951 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3952 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 3953 3954 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3955 return (ret == 0) ? OS_OK : OS_ERR; 3956 } 3957 3958 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3959 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3960 *priority_ptr = java_to_os_priority[NormPriority]; 3961 return OS_OK; 3962 } 3963 3964 errno = 0; 3965 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3966 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3967 } 3968 3969 // Hint to the underlying OS that a task switch would not be good. 3970 // Void return because it's a hint and can fail. 3971 void os::hint_no_preempt() {} 3972 3973 //////////////////////////////////////////////////////////////////////////////// 3974 // suspend/resume support 3975 3976 // the low-level signal-based suspend/resume support is a remnant from the 3977 // old VM-suspension that used to be for java-suspension, safepoints etc, 3978 // within hotspot. Now there is a single use-case for this: 3979 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3980 // that runs in the watcher thread. 3981 // The remaining code is greatly simplified from the more general suspension 3982 // code that used to be used. 3983 // 3984 // The protocol is quite simple: 3985 // - suspend: 3986 // - sends a signal to the target thread 3987 // - polls the suspend state of the osthread using a yield loop 3988 // - target thread signal handler (SR_handler) sets suspend state 3989 // and blocks in sigsuspend until continued 3990 // - resume: 3991 // - sets target osthread state to continue 3992 // - sends signal to end the sigsuspend loop in the SR_handler 3993 // 3994 // Note that the SR_lock plays no role in this suspend/resume protocol. 3995 // 3996 3997 static void resume_clear_context(OSThread *osthread) { 3998 osthread->set_ucontext(NULL); 3999 osthread->set_siginfo(NULL); 4000 } 4001 4002 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 4003 osthread->set_ucontext(context); 4004 osthread->set_siginfo(siginfo); 4005 } 4006 4007 // 4008 // Handler function invoked when a thread's execution is suspended or 4009 // resumed. We have to be careful that only async-safe functions are 4010 // called here (Note: most pthread functions are not async safe and 4011 // should be avoided.) 4012 // 4013 // Note: sigwait() is a more natural fit than sigsuspend() from an 4014 // interface point of view, but sigwait() prevents the signal hander 4015 // from being run. libpthread would get very confused by not having 4016 // its signal handlers run and prevents sigwait()'s use with the 4017 // mutex granting granting signal. 4018 // 4019 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 4020 // 4021 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 4022 // Save and restore errno to avoid confusing native code with EINTR 4023 // after sigsuspend. 4024 int old_errno = errno; 4025 4026 Thread* thread = Thread::current(); 4027 OSThread* osthread = thread->osthread(); 4028 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 4029 4030 os::SuspendResume::State current = osthread->sr.state(); 4031 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 4032 suspend_save_context(osthread, siginfo, context); 4033 4034 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 4035 os::SuspendResume::State state = osthread->sr.suspended(); 4036 if (state == os::SuspendResume::SR_SUSPENDED) { 4037 sigset_t suspend_set; // signals for sigsuspend() 4038 4039 // get current set of blocked signals and unblock resume signal 4040 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 4041 sigdelset(&suspend_set, SR_signum); 4042 4043 sr_semaphore.signal(); 4044 // wait here until we are resumed 4045 while (1) { 4046 sigsuspend(&suspend_set); 4047 4048 os::SuspendResume::State result = osthread->sr.running(); 4049 if (result == os::SuspendResume::SR_RUNNING) { 4050 sr_semaphore.signal(); 4051 break; 4052 } 4053 } 4054 4055 } else if (state == os::SuspendResume::SR_RUNNING) { 4056 // request was cancelled, continue 4057 } else { 4058 ShouldNotReachHere(); 4059 } 4060 4061 resume_clear_context(osthread); 4062 } else if (current == os::SuspendResume::SR_RUNNING) { 4063 // request was cancelled, continue 4064 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 4065 // ignore 4066 } else { 4067 // ignore 4068 } 4069 4070 errno = old_errno; 4071 } 4072 4073 4074 static int SR_initialize() { 4075 struct sigaction act; 4076 char *s; 4077 /* Get signal number to use for suspend/resume */ 4078 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 4079 int sig = ::strtol(s, 0, 10); 4080 if (sig > 0 || sig < _NSIG) { 4081 SR_signum = sig; 4082 } 4083 } 4084 4085 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 4086 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 4087 4088 sigemptyset(&SR_sigset); 4089 sigaddset(&SR_sigset, SR_signum); 4090 4091 /* Set up signal handler for suspend/resume */ 4092 act.sa_flags = SA_RESTART|SA_SIGINFO; 4093 act.sa_handler = (void (*)(int)) SR_handler; 4094 4095 // SR_signum is blocked by default. 4096 // 4528190 - We also need to block pthread restart signal (32 on all 4097 // supported Linux platforms). Note that LinuxThreads need to block 4098 // this signal for all threads to work properly. So we don't have 4099 // to use hard-coded signal number when setting up the mask. 4100 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4101 4102 if (sigaction(SR_signum, &act, 0) == -1) { 4103 return -1; 4104 } 4105 4106 // Save signal flag 4107 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4108 return 0; 4109 } 4110 4111 static int sr_notify(OSThread* osthread) { 4112 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4113 assert_status(status == 0, status, "pthread_kill"); 4114 return status; 4115 } 4116 4117 // "Randomly" selected value for how long we want to spin 4118 // before bailing out on suspending a thread, also how often 4119 // we send a signal to a thread we want to resume 4120 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4121 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4122 4123 // returns true on success and false on error - really an error is fatal 4124 // but this seems the normal response to library errors 4125 static bool do_suspend(OSThread* osthread) { 4126 assert(osthread->sr.is_running(), "thread should be running"); 4127 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4128 4129 // mark as suspended and send signal 4130 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4131 // failed to switch, state wasn't running? 4132 ShouldNotReachHere(); 4133 return false; 4134 } 4135 4136 if (sr_notify(osthread) != 0) { 4137 ShouldNotReachHere(); 4138 } 4139 4140 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4141 while (true) { 4142 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4143 break; 4144 } else { 4145 // timeout 4146 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4147 if (cancelled == os::SuspendResume::SR_RUNNING) { 4148 return false; 4149 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4150 // make sure that we consume the signal on the semaphore as well 4151 sr_semaphore.wait(); 4152 break; 4153 } else { 4154 ShouldNotReachHere(); 4155 return false; 4156 } 4157 } 4158 } 4159 4160 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4161 return true; 4162 } 4163 4164 static void do_resume(OSThread* osthread) { 4165 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4166 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4167 4168 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4169 // failed to switch to WAKEUP_REQUEST 4170 ShouldNotReachHere(); 4171 return; 4172 } 4173 4174 while (true) { 4175 if (sr_notify(osthread) == 0) { 4176 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4177 if (osthread->sr.is_running()) { 4178 return; 4179 } 4180 } 4181 } else { 4182 ShouldNotReachHere(); 4183 } 4184 } 4185 4186 guarantee(osthread->sr.is_running(), "Must be running!"); 4187 } 4188 4189 //////////////////////////////////////////////////////////////////////////////// 4190 // interrupt support 4191 4192 void os::interrupt(Thread* thread) { 4193 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 4194 "possibility of dangling Thread pointer"); 4195 4196 OSThread* osthread = thread->osthread(); 4197 4198 if (!osthread->interrupted()) { 4199 osthread->set_interrupted(true); 4200 // More than one thread can get here with the same value of osthread, 4201 // resulting in multiple notifications. We do, however, want the store 4202 // to interrupted() to be visible to other threads before we execute unpark(). 4203 OrderAccess::fence(); 4204 ParkEvent * const slp = thread->_SleepEvent ; 4205 if (slp != NULL) slp->unpark() ; 4206 } 4207 4208 // For JSR166. Unpark even if interrupt status already was set 4209 if (thread->is_Java_thread()) 4210 ((JavaThread*)thread)->parker()->unpark(); 4211 4212 ParkEvent * ev = thread->_ParkEvent ; 4213 if (ev != NULL) ev->unpark() ; 4214 4215 } 4216 4217 bool os::is_interrupted(Thread* thread, bool clear_interrupted) { 4218 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 4219 "possibility of dangling Thread pointer"); 4220 4221 OSThread* osthread = thread->osthread(); 4222 4223 bool interrupted = osthread->interrupted(); 4224 4225 if (interrupted && clear_interrupted) { 4226 osthread->set_interrupted(false); 4227 // consider thread->_SleepEvent->reset() ... optional optimization 4228 } 4229 4230 return interrupted; 4231 } 4232 4233 /////////////////////////////////////////////////////////////////////////////////// 4234 // signal handling (except suspend/resume) 4235 4236 // This routine may be used by user applications as a "hook" to catch signals. 4237 // The user-defined signal handler must pass unrecognized signals to this 4238 // routine, and if it returns true (non-zero), then the signal handler must 4239 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4240 // routine will never retun false (zero), but instead will execute a VM panic 4241 // routine kill the process. 4242 // 4243 // If this routine returns false, it is OK to call it again. This allows 4244 // the user-defined signal handler to perform checks either before or after 4245 // the VM performs its own checks. Naturally, the user code would be making 4246 // a serious error if it tried to handle an exception (such as a null check 4247 // or breakpoint) that the VM was generating for its own correct operation. 4248 // 4249 // This routine may recognize any of the following kinds of signals: 4250 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4251 // It should be consulted by handlers for any of those signals. 4252 // 4253 // The caller of this routine must pass in the three arguments supplied 4254 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4255 // field of the structure passed to sigaction(). This routine assumes that 4256 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4257 // 4258 // Note that the VM will print warnings if it detects conflicting signal 4259 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4260 // 4261 extern "C" JNIEXPORT int 4262 JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 4263 void* ucontext, int abort_if_unrecognized); 4264 4265 void signalHandler(int sig, siginfo_t* info, void* uc) { 4266 assert(info != NULL && uc != NULL, "it must be old kernel"); 4267 int orig_errno = errno; // Preserve errno value over signal handler. 4268 JVM_handle_linux_signal(sig, info, uc, true); 4269 errno = orig_errno; 4270 } 4271 4272 4273 // This boolean allows users to forward their own non-matching signals 4274 // to JVM_handle_linux_signal, harmlessly. 4275 bool os::Linux::signal_handlers_are_installed = false; 4276 4277 // For signal-chaining 4278 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4279 unsigned int os::Linux::sigs = 0; 4280 bool os::Linux::libjsig_is_loaded = false; 4281 typedef struct sigaction *(*get_signal_t)(int); 4282 get_signal_t os::Linux::get_signal_action = NULL; 4283 4284 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4285 struct sigaction *actp = NULL; 4286 4287 if (libjsig_is_loaded) { 4288 // Retrieve the old signal handler from libjsig 4289 actp = (*get_signal_action)(sig); 4290 } 4291 if (actp == NULL) { 4292 // Retrieve the preinstalled signal handler from jvm 4293 actp = get_preinstalled_handler(sig); 4294 } 4295 4296 return actp; 4297 } 4298 4299 static bool call_chained_handler(struct sigaction *actp, int sig, 4300 siginfo_t *siginfo, void *context) { 4301 // Call the old signal handler 4302 if (actp->sa_handler == SIG_DFL) { 4303 // It's more reasonable to let jvm treat it as an unexpected exception 4304 // instead of taking the default action. 4305 return false; 4306 } else if (actp->sa_handler != SIG_IGN) { 4307 if ((actp->sa_flags & SA_NODEFER) == 0) { 4308 // automaticlly block the signal 4309 sigaddset(&(actp->sa_mask), sig); 4310 } 4311 4312 sa_handler_t hand; 4313 sa_sigaction_t sa; 4314 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4315 // retrieve the chained handler 4316 if (siginfo_flag_set) { 4317 sa = actp->sa_sigaction; 4318 } else { 4319 hand = actp->sa_handler; 4320 } 4321 4322 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4323 actp->sa_handler = SIG_DFL; 4324 } 4325 4326 // try to honor the signal mask 4327 sigset_t oset; 4328 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4329 4330 // call into the chained handler 4331 if (siginfo_flag_set) { 4332 (*sa)(sig, siginfo, context); 4333 } else { 4334 (*hand)(sig); 4335 } 4336 4337 // restore the signal mask 4338 pthread_sigmask(SIG_SETMASK, &oset, 0); 4339 } 4340 // Tell jvm's signal handler the signal is taken care of. 4341 return true; 4342 } 4343 4344 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4345 bool chained = false; 4346 // signal-chaining 4347 if (UseSignalChaining) { 4348 struct sigaction *actp = get_chained_signal_action(sig); 4349 if (actp != NULL) { 4350 chained = call_chained_handler(actp, sig, siginfo, context); 4351 } 4352 } 4353 return chained; 4354 } 4355 4356 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4357 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 4358 return &sigact[sig]; 4359 } 4360 return NULL; 4361 } 4362 4363 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4364 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4365 sigact[sig] = oldAct; 4366 sigs |= (unsigned int)1 << sig; 4367 } 4368 4369 // for diagnostic 4370 int os::Linux::sigflags[MAXSIGNUM]; 4371 4372 int os::Linux::get_our_sigflags(int sig) { 4373 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4374 return sigflags[sig]; 4375 } 4376 4377 void os::Linux::set_our_sigflags(int sig, int flags) { 4378 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4379 sigflags[sig] = flags; 4380 } 4381 4382 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4383 // Check for overwrite. 4384 struct sigaction oldAct; 4385 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4386 4387 void* oldhand = oldAct.sa_sigaction 4388 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4389 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4390 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4391 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4392 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4393 if (AllowUserSignalHandlers || !set_installed) { 4394 // Do not overwrite; user takes responsibility to forward to us. 4395 return; 4396 } else if (UseSignalChaining) { 4397 // save the old handler in jvm 4398 save_preinstalled_handler(sig, oldAct); 4399 // libjsig also interposes the sigaction() call below and saves the 4400 // old sigaction on it own. 4401 } else { 4402 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4403 "%#lx for signal %d.", (long)oldhand, sig)); 4404 } 4405 } 4406 4407 struct sigaction sigAct; 4408 sigfillset(&(sigAct.sa_mask)); 4409 sigAct.sa_handler = SIG_DFL; 4410 if (!set_installed) { 4411 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4412 } else { 4413 sigAct.sa_sigaction = signalHandler; 4414 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4415 } 4416 // Save flags, which are set by ours 4417 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4418 sigflags[sig] = sigAct.sa_flags; 4419 4420 int ret = sigaction(sig, &sigAct, &oldAct); 4421 assert(ret == 0, "check"); 4422 4423 void* oldhand2 = oldAct.sa_sigaction 4424 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4425 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4426 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4427 } 4428 4429 // install signal handlers for signals that HotSpot needs to 4430 // handle in order to support Java-level exception handling. 4431 4432 void os::Linux::install_signal_handlers() { 4433 if (!signal_handlers_are_installed) { 4434 signal_handlers_are_installed = true; 4435 4436 // signal-chaining 4437 typedef void (*signal_setting_t)(); 4438 signal_setting_t begin_signal_setting = NULL; 4439 signal_setting_t end_signal_setting = NULL; 4440 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4441 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4442 if (begin_signal_setting != NULL) { 4443 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4444 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4445 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4446 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4447 libjsig_is_loaded = true; 4448 assert(UseSignalChaining, "should enable signal-chaining"); 4449 } 4450 if (libjsig_is_loaded) { 4451 // Tell libjsig jvm is setting signal handlers 4452 (*begin_signal_setting)(); 4453 } 4454 4455 set_signal_handler(SIGSEGV, true); 4456 set_signal_handler(SIGPIPE, true); 4457 set_signal_handler(SIGBUS, true); 4458 set_signal_handler(SIGILL, true); 4459 set_signal_handler(SIGFPE, true); 4460 #if defined(PPC64) 4461 set_signal_handler(SIGTRAP, true); 4462 #endif 4463 set_signal_handler(SIGXFSZ, true); 4464 4465 if (libjsig_is_loaded) { 4466 // Tell libjsig jvm finishes setting signal handlers 4467 (*end_signal_setting)(); 4468 } 4469 4470 // We don't activate signal checker if libjsig is in place, we trust ourselves 4471 // and if UserSignalHandler is installed all bets are off. 4472 // Log that signal checking is off only if -verbose:jni is specified. 4473 if (CheckJNICalls) { 4474 if (libjsig_is_loaded) { 4475 if (PrintJNIResolving) { 4476 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4477 } 4478 check_signals = false; 4479 } 4480 if (AllowUserSignalHandlers) { 4481 if (PrintJNIResolving) { 4482 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4483 } 4484 check_signals = false; 4485 } 4486 } 4487 } 4488 } 4489 4490 // This is the fastest way to get thread cpu time on Linux. 4491 // Returns cpu time (user+sys) for any thread, not only for current. 4492 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4493 // It might work on 2.6.10+ with a special kernel/glibc patch. 4494 // For reference, please, see IEEE Std 1003.1-2004: 4495 // http://www.unix.org/single_unix_specification 4496 4497 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4498 struct timespec tp; 4499 int rc = os::Linux::clock_gettime(clockid, &tp); 4500 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4501 4502 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4503 } 4504 4505 ///// 4506 // glibc on Linux platform uses non-documented flag 4507 // to indicate, that some special sort of signal 4508 // trampoline is used. 4509 // We will never set this flag, and we should 4510 // ignore this flag in our diagnostic 4511 #ifdef SIGNIFICANT_SIGNAL_MASK 4512 #undef SIGNIFICANT_SIGNAL_MASK 4513 #endif 4514 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4515 4516 static const char* get_signal_handler_name(address handler, 4517 char* buf, int buflen) { 4518 int offset; 4519 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4520 if (found) { 4521 // skip directory names 4522 const char *p1, *p2; 4523 p1 = buf; 4524 size_t len = strlen(os::file_separator()); 4525 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4526 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4527 } else { 4528 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4529 } 4530 return buf; 4531 } 4532 4533 static void print_signal_handler(outputStream* st, int sig, 4534 char* buf, size_t buflen) { 4535 struct sigaction sa; 4536 4537 sigaction(sig, NULL, &sa); 4538 4539 // See comment for SIGNIFICANT_SIGNAL_MASK define 4540 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4541 4542 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4543 4544 address handler = (sa.sa_flags & SA_SIGINFO) 4545 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4546 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4547 4548 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4549 st->print("SIG_DFL"); 4550 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4551 st->print("SIG_IGN"); 4552 } else { 4553 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4554 } 4555 4556 st->print(", sa_mask[0]="); 4557 os::Posix::print_signal_set_short(st, &sa.sa_mask); 4558 4559 address rh = VMError::get_resetted_sighandler(sig); 4560 // May be, handler was resetted by VMError? 4561 if(rh != NULL) { 4562 handler = rh; 4563 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4564 } 4565 4566 st->print(", sa_flags="); 4567 os::Posix::print_sa_flags(st, sa.sa_flags); 4568 4569 // Check: is it our handler? 4570 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4571 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4572 // It is our signal handler 4573 // check for flags, reset system-used one! 4574 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4575 st->print( 4576 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4577 os::Linux::get_our_sigflags(sig)); 4578 } 4579 } 4580 st->cr(); 4581 } 4582 4583 4584 #define DO_SIGNAL_CHECK(sig) \ 4585 if (!sigismember(&check_signal_done, sig)) \ 4586 os::Linux::check_signal_handler(sig) 4587 4588 // This method is a periodic task to check for misbehaving JNI applications 4589 // under CheckJNI, we can add any periodic checks here 4590 4591 void os::run_periodic_checks() { 4592 4593 if (check_signals == false) return; 4594 4595 // SEGV and BUS if overridden could potentially prevent 4596 // generation of hs*.log in the event of a crash, debugging 4597 // such a case can be very challenging, so we absolutely 4598 // check the following for a good measure: 4599 DO_SIGNAL_CHECK(SIGSEGV); 4600 DO_SIGNAL_CHECK(SIGILL); 4601 DO_SIGNAL_CHECK(SIGFPE); 4602 DO_SIGNAL_CHECK(SIGBUS); 4603 DO_SIGNAL_CHECK(SIGPIPE); 4604 DO_SIGNAL_CHECK(SIGXFSZ); 4605 #if defined(PPC64) 4606 DO_SIGNAL_CHECK(SIGTRAP); 4607 #endif 4608 4609 // ReduceSignalUsage allows the user to override these handlers 4610 // see comments at the very top and jvm_solaris.h 4611 if (!ReduceSignalUsage) { 4612 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4613 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4614 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4615 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4616 } 4617 4618 DO_SIGNAL_CHECK(SR_signum); 4619 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4620 } 4621 4622 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4623 4624 static os_sigaction_t os_sigaction = NULL; 4625 4626 void os::Linux::check_signal_handler(int sig) { 4627 char buf[O_BUFLEN]; 4628 address jvmHandler = NULL; 4629 4630 4631 struct sigaction act; 4632 if (os_sigaction == NULL) { 4633 // only trust the default sigaction, in case it has been interposed 4634 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4635 if (os_sigaction == NULL) return; 4636 } 4637 4638 os_sigaction(sig, (struct sigaction*)NULL, &act); 4639 4640 4641 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4642 4643 address thisHandler = (act.sa_flags & SA_SIGINFO) 4644 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4645 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 4646 4647 4648 switch(sig) { 4649 case SIGSEGV: 4650 case SIGBUS: 4651 case SIGFPE: 4652 case SIGPIPE: 4653 case SIGILL: 4654 case SIGXFSZ: 4655 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4656 break; 4657 4658 case SHUTDOWN1_SIGNAL: 4659 case SHUTDOWN2_SIGNAL: 4660 case SHUTDOWN3_SIGNAL: 4661 case BREAK_SIGNAL: 4662 jvmHandler = (address)user_handler(); 4663 break; 4664 4665 case INTERRUPT_SIGNAL: 4666 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4667 break; 4668 4669 default: 4670 if (sig == SR_signum) { 4671 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4672 } else { 4673 return; 4674 } 4675 break; 4676 } 4677 4678 if (thisHandler != jvmHandler) { 4679 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4680 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4681 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4682 // No need to check this sig any longer 4683 sigaddset(&check_signal_done, sig); 4684 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4685 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4686 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4687 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4688 // No need to check this sig any longer 4689 sigaddset(&check_signal_done, sig); 4690 } 4691 4692 // Dump all the signal 4693 if (sigismember(&check_signal_done, sig)) { 4694 print_signal_handlers(tty, buf, O_BUFLEN); 4695 } 4696 } 4697 4698 extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 4699 4700 extern bool signal_name(int signo, char* buf, size_t len); 4701 4702 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4703 if (0 < exception_code && exception_code <= SIGRTMAX) { 4704 // signal 4705 if (!signal_name(exception_code, buf, size)) { 4706 jio_snprintf(buf, size, "SIG%d", exception_code); 4707 } 4708 return buf; 4709 } else { 4710 return NULL; 4711 } 4712 } 4713 4714 // this is called _before_ the most of global arguments have been parsed 4715 void os::init(void) { 4716 char dummy; /* used to get a guess on initial stack address */ 4717 // first_hrtime = gethrtime(); 4718 4719 // With LinuxThreads the JavaMain thread pid (primordial thread) 4720 // is different than the pid of the java launcher thread. 4721 // So, on Linux, the launcher thread pid is passed to the VM 4722 // via the sun.java.launcher.pid property. 4723 // Use this property instead of getpid() if it was correctly passed. 4724 // See bug 6351349. 4725 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4726 4727 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4728 4729 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4730 4731 init_random(1234567); 4732 4733 ThreadCritical::initialize(); 4734 4735 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4736 if (Linux::page_size() == -1) { 4737 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4738 strerror(errno))); 4739 } 4740 init_page_sizes((size_t) Linux::page_size()); 4741 4742 Linux::initialize_system_info(); 4743 4744 // main_thread points to the aboriginal thread 4745 Linux::_main_thread = pthread_self(); 4746 4747 Linux::clock_init(); 4748 initial_time_count = javaTimeNanos(); 4749 4750 // pthread_condattr initialization for monotonic clock 4751 int status; 4752 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4753 if ((status = pthread_condattr_init(_condattr)) != 0) { 4754 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4755 } 4756 // Only set the clock if CLOCK_MONOTONIC is available 4757 if (Linux::supports_monotonic_clock()) { 4758 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4759 if (status == EINVAL) { 4760 warning("Unable to use monotonic clock with relative timed-waits" \ 4761 " - changes to the time-of-day clock may have adverse affects"); 4762 } else { 4763 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4764 } 4765 } 4766 } 4767 // else it defaults to CLOCK_REALTIME 4768 4769 pthread_mutex_init(&dl_mutex, NULL); 4770 4771 // If the pagesize of the VM is greater than 8K determine the appropriate 4772 // number of initial guard pages. The user can change this with the 4773 // command line arguments, if needed. 4774 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4775 StackYellowPages = 1; 4776 StackRedPages = 1; 4777 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4778 } 4779 } 4780 4781 // To install functions for atexit system call 4782 extern "C" { 4783 static void perfMemory_exit_helper() { 4784 perfMemory_exit(); 4785 } 4786 } 4787 4788 // this is called _after_ the global arguments have been parsed 4789 jint os::init_2(void) 4790 { 4791 Linux::fast_thread_clock_init(); 4792 4793 // Allocate a single page and mark it as readable for safepoint polling 4794 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4795 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 4796 4797 os::set_polling_page( polling_page ); 4798 4799 #ifndef PRODUCT 4800 if(Verbose && PrintMiscellaneous) 4801 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 4802 #endif 4803 4804 if (!UseMembar) { 4805 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4806 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4807 os::set_memory_serialize_page( mem_serialize_page ); 4808 4809 #ifndef PRODUCT 4810 if(Verbose && PrintMiscellaneous) 4811 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 4812 #endif 4813 } 4814 4815 // initialize suspend/resume support - must do this before signal_sets_init() 4816 if (SR_initialize() != 0) { 4817 perror("SR_initialize failed"); 4818 return JNI_ERR; 4819 } 4820 4821 Linux::signal_sets_init(); 4822 Linux::install_signal_handlers(); 4823 4824 // Check minimum allowable stack size for thread creation and to initialize 4825 // the java system classes, including StackOverflowError - depends on page 4826 // size. Add a page for compiler2 recursion in main thread. 4827 // Add in 2*BytesPerWord times page size to account for VM stack during 4828 // class initialization depending on 32 or 64 bit VM. 4829 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4830 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4831 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4832 4833 size_t threadStackSizeInBytes = ThreadStackSize * K; 4834 if (threadStackSizeInBytes != 0 && 4835 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4836 tty->print_cr("\nThe stack size specified is too small, " 4837 "Specify at least %dk", 4838 os::Linux::min_stack_allowed/ K); 4839 return JNI_ERR; 4840 } 4841 4842 // Make the stack size a multiple of the page size so that 4843 // the yellow/red zones can be guarded. 4844 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4845 vm_page_size())); 4846 4847 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4848 4849 #if defined(IA32) 4850 workaround_expand_exec_shield_cs_limit(); 4851 #endif 4852 4853 Linux::libpthread_init(); 4854 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4855 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4856 Linux::glibc_version(), Linux::libpthread_version(), 4857 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4858 } 4859 4860 if (UseNUMA) { 4861 if (!Linux::libnuma_init()) { 4862 UseNUMA = false; 4863 } else { 4864 if ((Linux::numa_max_node() < 1)) { 4865 // There's only one node(they start from 0), disable NUMA. 4866 UseNUMA = false; 4867 } 4868 } 4869 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4870 // we can make the adaptive lgrp chunk resizing work. If the user specified 4871 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4872 // disable adaptive resizing. 4873 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4874 if (FLAG_IS_DEFAULT(UseNUMA)) { 4875 UseNUMA = false; 4876 } else { 4877 if (FLAG_IS_DEFAULT(UseLargePages) && 4878 FLAG_IS_DEFAULT(UseSHM) && 4879 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4880 UseLargePages = false; 4881 } else { 4882 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4883 UseAdaptiveSizePolicy = false; 4884 UseAdaptiveNUMAChunkSizing = false; 4885 } 4886 } 4887 } 4888 if (!UseNUMA && ForceNUMA) { 4889 UseNUMA = true; 4890 } 4891 } 4892 4893 if (MaxFDLimit) { 4894 // set the number of file descriptors to max. print out error 4895 // if getrlimit/setrlimit fails but continue regardless. 4896 struct rlimit nbr_files; 4897 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4898 if (status != 0) { 4899 if (PrintMiscellaneous && (Verbose || WizardMode)) 4900 perror("os::init_2 getrlimit failed"); 4901 } else { 4902 nbr_files.rlim_cur = nbr_files.rlim_max; 4903 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4904 if (status != 0) { 4905 if (PrintMiscellaneous && (Verbose || WizardMode)) 4906 perror("os::init_2 setrlimit failed"); 4907 } 4908 } 4909 } 4910 4911 // Initialize lock used to serialize thread creation (see os::create_thread) 4912 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4913 4914 // at-exit methods are called in the reverse order of their registration. 4915 // atexit functions are called on return from main or as a result of a 4916 // call to exit(3C). There can be only 32 of these functions registered 4917 // and atexit() does not set errno. 4918 4919 if (PerfAllowAtExitRegistration) { 4920 // only register atexit functions if PerfAllowAtExitRegistration is set. 4921 // atexit functions can be delayed until process exit time, which 4922 // can be problematic for embedded VM situations. Embedded VMs should 4923 // call DestroyJavaVM() to assure that VM resources are released. 4924 4925 // note: perfMemory_exit_helper atexit function may be removed in 4926 // the future if the appropriate cleanup code can be added to the 4927 // VM_Exit VMOperation's doit method. 4928 if (atexit(perfMemory_exit_helper) != 0) { 4929 warning("os::init_2 atexit(perfMemory_exit_helper) failed"); 4930 } 4931 } 4932 4933 // initialize thread priority policy 4934 prio_init(); 4935 4936 return JNI_OK; 4937 } 4938 4939 // this is called at the end of vm_initialization 4940 void os::init_3(void) { 4941 #ifdef JAVASE_EMBEDDED 4942 // Start the MemNotifyThread 4943 if (LowMemoryProtection) { 4944 MemNotifyThread::start(); 4945 } 4946 return; 4947 #endif 4948 } 4949 4950 // Mark the polling page as unreadable 4951 void os::make_polling_page_unreadable(void) { 4952 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 4953 fatal("Could not disable polling page"); 4954 }; 4955 4956 // Mark the polling page as readable 4957 void os::make_polling_page_readable(void) { 4958 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4959 fatal("Could not enable polling page"); 4960 } 4961 }; 4962 4963 int os::active_processor_count() { 4964 // Linux doesn't yet have a (official) notion of processor sets, 4965 // so just return the number of online processors. 4966 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4967 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4968 return online_cpus; 4969 } 4970 4971 void os::set_native_thread_name(const char *name) { 4972 // Not yet implemented. 4973 return; 4974 } 4975 4976 bool os::distribute_processes(uint length, uint* distribution) { 4977 // Not yet implemented. 4978 return false; 4979 } 4980 4981 bool os::bind_to_processor(uint processor_id) { 4982 // Not yet implemented. 4983 return false; 4984 } 4985 4986 /// 4987 4988 void os::SuspendedThreadTask::internal_do_task() { 4989 if (do_suspend(_thread->osthread())) { 4990 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4991 do_task(context); 4992 do_resume(_thread->osthread()); 4993 } 4994 } 4995 4996 class PcFetcher : public os::SuspendedThreadTask { 4997 public: 4998 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4999 ExtendedPC result(); 5000 protected: 5001 void do_task(const os::SuspendedThreadTaskContext& context); 5002 private: 5003 ExtendedPC _epc; 5004 }; 5005 5006 ExtendedPC PcFetcher::result() { 5007 guarantee(is_done(), "task is not done yet."); 5008 return _epc; 5009 } 5010 5011 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 5012 Thread* thread = context.thread(); 5013 OSThread* osthread = thread->osthread(); 5014 if (osthread->ucontext() != NULL) { 5015 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 5016 } else { 5017 // NULL context is unexpected, double-check this is the VMThread 5018 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 5019 } 5020 } 5021 5022 // Suspends the target using the signal mechanism and then grabs the PC before 5023 // resuming the target. Used by the flat-profiler only 5024 ExtendedPC os::get_thread_pc(Thread* thread) { 5025 // Make sure that it is called by the watcher for the VMThread 5026 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 5027 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 5028 5029 PcFetcher fetcher(thread); 5030 fetcher.run(); 5031 return fetcher.result(); 5032 } 5033 5034 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 5035 { 5036 if (is_NPTL()) { 5037 return pthread_cond_timedwait(_cond, _mutex, _abstime); 5038 } else { 5039 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 5040 // word back to default 64bit precision if condvar is signaled. Java 5041 // wants 53bit precision. Save and restore current value. 5042 int fpu = get_fpu_control_word(); 5043 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 5044 set_fpu_control_word(fpu); 5045 return status; 5046 } 5047 } 5048 5049 //////////////////////////////////////////////////////////////////////////////// 5050 // debug support 5051 5052 bool os::find(address addr, outputStream* st) { 5053 Dl_info dlinfo; 5054 memset(&dlinfo, 0, sizeof(dlinfo)); 5055 if (dladdr(addr, &dlinfo) != 0) { 5056 st->print(PTR_FORMAT ": ", addr); 5057 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 5058 st->print("%s+%#x", dlinfo.dli_sname, 5059 addr - (intptr_t)dlinfo.dli_saddr); 5060 } else if (dlinfo.dli_fbase != NULL) { 5061 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 5062 } else { 5063 st->print("<absolute address>"); 5064 } 5065 if (dlinfo.dli_fname != NULL) { 5066 st->print(" in %s", dlinfo.dli_fname); 5067 } 5068 if (dlinfo.dli_fbase != NULL) { 5069 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 5070 } 5071 st->cr(); 5072 5073 if (Verbose) { 5074 // decode some bytes around the PC 5075 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 5076 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 5077 address lowest = (address) dlinfo.dli_sname; 5078 if (!lowest) lowest = (address) dlinfo.dli_fbase; 5079 if (begin < lowest) begin = lowest; 5080 Dl_info dlinfo2; 5081 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 5082 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 5083 end = (address) dlinfo2.dli_saddr; 5084 Disassembler::decode(begin, end, st); 5085 } 5086 return true; 5087 } 5088 return false; 5089 } 5090 5091 //////////////////////////////////////////////////////////////////////////////// 5092 // misc 5093 5094 // This does not do anything on Linux. This is basically a hook for being 5095 // able to use structured exception handling (thread-local exception filters) 5096 // on, e.g., Win32. 5097 void 5098 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 5099 JavaCallArguments* args, Thread* thread) { 5100 f(value, method, args, thread); 5101 } 5102 5103 void os::print_statistics() { 5104 } 5105 5106 int os::message_box(const char* title, const char* message) { 5107 int i; 5108 fdStream err(defaultStream::error_fd()); 5109 for (i = 0; i < 78; i++) err.print_raw("="); 5110 err.cr(); 5111 err.print_raw_cr(title); 5112 for (i = 0; i < 78; i++) err.print_raw("-"); 5113 err.cr(); 5114 err.print_raw_cr(message); 5115 for (i = 0; i < 78; i++) err.print_raw("="); 5116 err.cr(); 5117 5118 char buf[16]; 5119 // Prevent process from exiting upon "read error" without consuming all CPU 5120 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 5121 5122 return buf[0] == 'y' || buf[0] == 'Y'; 5123 } 5124 5125 int os::stat(const char *path, struct stat *sbuf) { 5126 char pathbuf[MAX_PATH]; 5127 if (strlen(path) > MAX_PATH - 1) { 5128 errno = ENAMETOOLONG; 5129 return -1; 5130 } 5131 os::native_path(strcpy(pathbuf, path)); 5132 return ::stat(pathbuf, sbuf); 5133 } 5134 5135 bool os::check_heap(bool force) { 5136 return true; 5137 } 5138 5139 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 5140 return ::vsnprintf(buf, count, format, args); 5141 } 5142 5143 // Is a (classpath) directory empty? 5144 bool os::dir_is_empty(const char* path) { 5145 DIR *dir = NULL; 5146 struct dirent *ptr; 5147 5148 dir = opendir(path); 5149 if (dir == NULL) return true; 5150 5151 /* Scan the directory */ 5152 bool result = true; 5153 char buf[sizeof(struct dirent) + MAX_PATH]; 5154 while (result && (ptr = ::readdir(dir)) != NULL) { 5155 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5156 result = false; 5157 } 5158 } 5159 closedir(dir); 5160 return result; 5161 } 5162 5163 // This code originates from JDK's sysOpen and open64_w 5164 // from src/solaris/hpi/src/system_md.c 5165 5166 #ifndef O_DELETE 5167 #define O_DELETE 0x10000 5168 #endif 5169 5170 // Open a file. Unlink the file immediately after open returns 5171 // if the specified oflag has the O_DELETE flag set. 5172 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c 5173 5174 int os::open(const char *path, int oflag, int mode) { 5175 5176 if (strlen(path) > MAX_PATH - 1) { 5177 errno = ENAMETOOLONG; 5178 return -1; 5179 } 5180 int fd; 5181 int o_delete = (oflag & O_DELETE); 5182 oflag = oflag & ~O_DELETE; 5183 5184 fd = ::open64(path, oflag, mode); 5185 if (fd == -1) return -1; 5186 5187 //If the open succeeded, the file might still be a directory 5188 { 5189 struct stat64 buf64; 5190 int ret = ::fstat64(fd, &buf64); 5191 int st_mode = buf64.st_mode; 5192 5193 if (ret != -1) { 5194 if ((st_mode & S_IFMT) == S_IFDIR) { 5195 errno = EISDIR; 5196 ::close(fd); 5197 return -1; 5198 } 5199 } else { 5200 ::close(fd); 5201 return -1; 5202 } 5203 } 5204 5205 /* 5206 * All file descriptors that are opened in the JVM and not 5207 * specifically destined for a subprocess should have the 5208 * close-on-exec flag set. If we don't set it, then careless 3rd 5209 * party native code might fork and exec without closing all 5210 * appropriate file descriptors (e.g. as we do in closeDescriptors in 5211 * UNIXProcess.c), and this in turn might: 5212 * 5213 * - cause end-of-file to fail to be detected on some file 5214 * descriptors, resulting in mysterious hangs, or 5215 * 5216 * - might cause an fopen in the subprocess to fail on a system 5217 * suffering from bug 1085341. 5218 * 5219 * (Yes, the default setting of the close-on-exec flag is a Unix 5220 * design flaw) 5221 * 5222 * See: 5223 * 1085341: 32-bit stdio routines should support file descriptors >255 5224 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5225 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5226 */ 5227 #ifdef FD_CLOEXEC 5228 { 5229 int flags = ::fcntl(fd, F_GETFD); 5230 if (flags != -1) 5231 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5232 } 5233 #endif 5234 5235 if (o_delete != 0) { 5236 ::unlink(path); 5237 } 5238 return fd; 5239 } 5240 5241 5242 // create binary file, rewriting existing file if required 5243 int os::create_binary_file(const char* path, bool rewrite_existing) { 5244 int oflags = O_WRONLY | O_CREAT; 5245 if (!rewrite_existing) { 5246 oflags |= O_EXCL; 5247 } 5248 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5249 } 5250 5251 // return current position of file pointer 5252 jlong os::current_file_offset(int fd) { 5253 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5254 } 5255 5256 // move file pointer to the specified offset 5257 jlong os::seek_to_file_offset(int fd, jlong offset) { 5258 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5259 } 5260 5261 // This code originates from JDK's sysAvailable 5262 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5263 5264 int os::available(int fd, jlong *bytes) { 5265 jlong cur, end; 5266 int mode; 5267 struct stat64 buf64; 5268 5269 if (::fstat64(fd, &buf64) >= 0) { 5270 mode = buf64.st_mode; 5271 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5272 /* 5273 * XXX: is the following call interruptible? If so, this might 5274 * need to go through the INTERRUPT_IO() wrapper as for other 5275 * blocking, interruptible calls in this file. 5276 */ 5277 int n; 5278 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5279 *bytes = n; 5280 return 1; 5281 } 5282 } 5283 } 5284 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5285 return 0; 5286 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5287 return 0; 5288 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5289 return 0; 5290 } 5291 *bytes = end - cur; 5292 return 1; 5293 } 5294 5295 int os::socket_available(int fd, jint *pbytes) { 5296 // Linux doc says EINTR not returned, unlike Solaris 5297 int ret = ::ioctl(fd, FIONREAD, pbytes); 5298 5299 //%% note ioctl can return 0 when successful, JVM_SocketAvailable 5300 // is expected to return 0 on failure and 1 on success to the jdk. 5301 return (ret < 0) ? 0 : 1; 5302 } 5303 5304 // Map a block of memory. 5305 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5306 char *addr, size_t bytes, bool read_only, 5307 bool allow_exec) { 5308 int prot; 5309 int flags = MAP_PRIVATE; 5310 5311 if (read_only) { 5312 prot = PROT_READ; 5313 } else { 5314 prot = PROT_READ | PROT_WRITE; 5315 } 5316 5317 if (allow_exec) { 5318 prot |= PROT_EXEC; 5319 } 5320 5321 if (addr != NULL) { 5322 flags |= MAP_FIXED; 5323 } 5324 5325 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5326 fd, file_offset); 5327 if (mapped_address == MAP_FAILED) { 5328 return NULL; 5329 } 5330 return mapped_address; 5331 } 5332 5333 5334 // Remap a block of memory. 5335 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5336 char *addr, size_t bytes, bool read_only, 5337 bool allow_exec) { 5338 // same as map_memory() on this OS 5339 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5340 allow_exec); 5341 } 5342 5343 5344 // Unmap a block of memory. 5345 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5346 return munmap(addr, bytes) == 0; 5347 } 5348 5349 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5350 5351 static clockid_t thread_cpu_clockid(Thread* thread) { 5352 pthread_t tid = thread->osthread()->pthread_id(); 5353 clockid_t clockid; 5354 5355 // Get thread clockid 5356 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5357 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5358 return clockid; 5359 } 5360 5361 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5362 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5363 // of a thread. 5364 // 5365 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5366 // the fast estimate available on the platform. 5367 5368 jlong os::current_thread_cpu_time() { 5369 if (os::Linux::supports_fast_thread_cpu_time()) { 5370 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5371 } else { 5372 // return user + sys since the cost is the same 5373 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5374 } 5375 } 5376 5377 jlong os::thread_cpu_time(Thread* thread) { 5378 // consistent with what current_thread_cpu_time() returns 5379 if (os::Linux::supports_fast_thread_cpu_time()) { 5380 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5381 } else { 5382 return slow_thread_cpu_time(thread, true /* user + sys */); 5383 } 5384 } 5385 5386 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5387 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5388 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5389 } else { 5390 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5391 } 5392 } 5393 5394 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5395 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5396 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5397 } else { 5398 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5399 } 5400 } 5401 5402 // 5403 // -1 on error. 5404 // 5405 5406 PRAGMA_DIAG_PUSH 5407 PRAGMA_FORMAT_NONLITERAL_IGNORED 5408 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5409 static bool proc_task_unchecked = true; 5410 static const char *proc_stat_path = "/proc/%d/stat"; 5411 pid_t tid = thread->osthread()->thread_id(); 5412 char *s; 5413 char stat[2048]; 5414 int statlen; 5415 char proc_name[64]; 5416 int count; 5417 long sys_time, user_time; 5418 char cdummy; 5419 int idummy; 5420 long ldummy; 5421 FILE *fp; 5422 5423 // The /proc/<tid>/stat aggregates per-process usage on 5424 // new Linux kernels 2.6+ where NPTL is supported. 5425 // The /proc/self/task/<tid>/stat still has the per-thread usage. 5426 // See bug 6328462. 5427 // There possibly can be cases where there is no directory 5428 // /proc/self/task, so we check its availability. 5429 if (proc_task_unchecked && os::Linux::is_NPTL()) { 5430 // This is executed only once 5431 proc_task_unchecked = false; 5432 fp = fopen("/proc/self/task", "r"); 5433 if (fp != NULL) { 5434 proc_stat_path = "/proc/self/task/%d/stat"; 5435 fclose(fp); 5436 } 5437 } 5438 5439 sprintf(proc_name, proc_stat_path, tid); 5440 fp = fopen(proc_name, "r"); 5441 if ( fp == NULL ) return -1; 5442 statlen = fread(stat, 1, 2047, fp); 5443 stat[statlen] = '\0'; 5444 fclose(fp); 5445 5446 // Skip pid and the command string. Note that we could be dealing with 5447 // weird command names, e.g. user could decide to rename java launcher 5448 // to "java 1.4.2 :)", then the stat file would look like 5449 // 1234 (java 1.4.2 :)) R ... ... 5450 // We don't really need to know the command string, just find the last 5451 // occurrence of ")" and then start parsing from there. See bug 4726580. 5452 s = strrchr(stat, ')'); 5453 if (s == NULL ) return -1; 5454 5455 // Skip blank chars 5456 do s++; while (isspace(*s)); 5457 5458 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5459 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5460 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5461 &user_time, &sys_time); 5462 if ( count != 13 ) return -1; 5463 if (user_sys_cpu_time) { 5464 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5465 } else { 5466 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5467 } 5468 } 5469 PRAGMA_DIAG_POP 5470 5471 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5472 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5473 info_ptr->may_skip_backward = false; // elapsed time not wall time 5474 info_ptr->may_skip_forward = false; // elapsed time not wall time 5475 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5476 } 5477 5478 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5479 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5480 info_ptr->may_skip_backward = false; // elapsed time not wall time 5481 info_ptr->may_skip_forward = false; // elapsed time not wall time 5482 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5483 } 5484 5485 bool os::is_thread_cpu_time_supported() { 5486 return true; 5487 } 5488 5489 // System loadavg support. Returns -1 if load average cannot be obtained. 5490 // Linux doesn't yet have a (official) notion of processor sets, 5491 // so just return the system wide load average. 5492 int os::loadavg(double loadavg[], int nelem) { 5493 return ::getloadavg(loadavg, nelem); 5494 } 5495 5496 void os::pause() { 5497 char filename[MAX_PATH]; 5498 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5499 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5500 } else { 5501 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5502 } 5503 5504 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5505 if (fd != -1) { 5506 struct stat buf; 5507 ::close(fd); 5508 while (::stat(filename, &buf) == 0) { 5509 (void)::poll(NULL, 0, 100); 5510 } 5511 } else { 5512 jio_fprintf(stderr, 5513 "Could not open pause file '%s', continuing immediately.\n", filename); 5514 } 5515 } 5516 5517 5518 // Refer to the comments in os_solaris.cpp park-unpark. 5519 // 5520 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5521 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5522 // For specifics regarding the bug see GLIBC BUGID 261237 : 5523 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5524 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5525 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5526 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5527 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5528 // and monitorenter when we're using 1-0 locking. All those operations may result in 5529 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5530 // of libpthread avoids the problem, but isn't practical. 5531 // 5532 // Possible remedies: 5533 // 5534 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5535 // This is palliative and probabilistic, however. If the thread is preempted 5536 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5537 // than the minimum period may have passed, and the abstime may be stale (in the 5538 // past) resultin in a hang. Using this technique reduces the odds of a hang 5539 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5540 // 5541 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5542 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5543 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5544 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5545 // thread. 5546 // 5547 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5548 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5549 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5550 // This also works well. In fact it avoids kernel-level scalability impediments 5551 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5552 // timers in a graceful fashion. 5553 // 5554 // 4. When the abstime value is in the past it appears that control returns 5555 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5556 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5557 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5558 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5559 // It may be possible to avoid reinitialization by checking the return 5560 // value from pthread_cond_timedwait(). In addition to reinitializing the 5561 // condvar we must establish the invariant that cond_signal() is only called 5562 // within critical sections protected by the adjunct mutex. This prevents 5563 // cond_signal() from "seeing" a condvar that's in the midst of being 5564 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5565 // desirable signal-after-unlock optimization that avoids futile context switching. 5566 // 5567 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5568 // structure when a condvar is used or initialized. cond_destroy() would 5569 // release the helper structure. Our reinitialize-after-timedwait fix 5570 // put excessive stress on malloc/free and locks protecting the c-heap. 5571 // 5572 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5573 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5574 // and only enabling the work-around for vulnerable environments. 5575 5576 // utility to compute the abstime argument to timedwait: 5577 // millis is the relative timeout time 5578 // abstime will be the absolute timeout time 5579 // TODO: replace compute_abstime() with unpackTime() 5580 5581 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5582 if (millis < 0) millis = 0; 5583 5584 jlong seconds = millis / 1000; 5585 millis %= 1000; 5586 if (seconds > 50000000) { // see man cond_timedwait(3T) 5587 seconds = 50000000; 5588 } 5589 5590 if (os::Linux::supports_monotonic_clock()) { 5591 struct timespec now; 5592 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5593 assert_status(status == 0, status, "clock_gettime"); 5594 abstime->tv_sec = now.tv_sec + seconds; 5595 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5596 if (nanos >= NANOSECS_PER_SEC) { 5597 abstime->tv_sec += 1; 5598 nanos -= NANOSECS_PER_SEC; 5599 } 5600 abstime->tv_nsec = nanos; 5601 } else { 5602 struct timeval now; 5603 int status = gettimeofday(&now, NULL); 5604 assert(status == 0, "gettimeofday"); 5605 abstime->tv_sec = now.tv_sec + seconds; 5606 long usec = now.tv_usec + millis * 1000; 5607 if (usec >= 1000000) { 5608 abstime->tv_sec += 1; 5609 usec -= 1000000; 5610 } 5611 abstime->tv_nsec = usec * 1000; 5612 } 5613 return abstime; 5614 } 5615 5616 5617 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 5618 // Conceptually TryPark() should be equivalent to park(0). 5619 5620 int os::PlatformEvent::TryPark() { 5621 for (;;) { 5622 const int v = _Event ; 5623 guarantee ((v == 0) || (v == 1), "invariant") ; 5624 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 5625 } 5626 } 5627 5628 void os::PlatformEvent::park() { // AKA "down()" 5629 // Invariant: Only the thread associated with the Event/PlatformEvent 5630 // may call park(). 5631 // TODO: assert that _Assoc != NULL or _Assoc == Self 5632 int v ; 5633 for (;;) { 5634 v = _Event ; 5635 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5636 } 5637 guarantee (v >= 0, "invariant") ; 5638 if (v == 0) { 5639 // Do this the hard way by blocking ... 5640 int status = pthread_mutex_lock(_mutex); 5641 assert_status(status == 0, status, "mutex_lock"); 5642 guarantee (_nParked == 0, "invariant") ; 5643 ++ _nParked ; 5644 while (_Event < 0) { 5645 status = pthread_cond_wait(_cond, _mutex); 5646 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5647 // Treat this the same as if the wait was interrupted 5648 if (status == ETIME) { status = EINTR; } 5649 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5650 } 5651 -- _nParked ; 5652 5653 _Event = 0 ; 5654 status = pthread_mutex_unlock(_mutex); 5655 assert_status(status == 0, status, "mutex_unlock"); 5656 // Paranoia to ensure our locked and lock-free paths interact 5657 // correctly with each other. 5658 OrderAccess::fence(); 5659 } 5660 guarantee (_Event >= 0, "invariant") ; 5661 } 5662 5663 int os::PlatformEvent::park(jlong millis) { 5664 guarantee (_nParked == 0, "invariant") ; 5665 5666 int v ; 5667 for (;;) { 5668 v = _Event ; 5669 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5670 } 5671 guarantee (v >= 0, "invariant") ; 5672 if (v != 0) return OS_OK ; 5673 5674 // We do this the hard way, by blocking the thread. 5675 // Consider enforcing a minimum timeout value. 5676 struct timespec abst; 5677 compute_abstime(&abst, millis); 5678 5679 int ret = OS_TIMEOUT; 5680 int status = pthread_mutex_lock(_mutex); 5681 assert_status(status == 0, status, "mutex_lock"); 5682 guarantee (_nParked == 0, "invariant") ; 5683 ++_nParked ; 5684 5685 // Object.wait(timo) will return because of 5686 // (a) notification 5687 // (b) timeout 5688 // (c) thread.interrupt 5689 // 5690 // Thread.interrupt and object.notify{All} both call Event::set. 5691 // That is, we treat thread.interrupt as a special case of notification. 5692 // The underlying Solaris implementation, cond_timedwait, admits 5693 // spurious/premature wakeups, but the JLS/JVM spec prevents the 5694 // JVM from making those visible to Java code. As such, we must 5695 // filter out spurious wakeups. We assume all ETIME returns are valid. 5696 // 5697 // TODO: properly differentiate simultaneous notify+interrupt. 5698 // In that case, we should propagate the notify to another waiter. 5699 5700 while (_Event < 0) { 5701 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5702 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5703 pthread_cond_destroy (_cond); 5704 pthread_cond_init (_cond, os::Linux::condAttr()) ; 5705 } 5706 assert_status(status == 0 || status == EINTR || 5707 status == ETIME || status == ETIMEDOUT, 5708 status, "cond_timedwait"); 5709 if (!FilterSpuriousWakeups) break ; // previous semantics 5710 if (status == ETIME || status == ETIMEDOUT) break ; 5711 // We consume and ignore EINTR and spurious wakeups. 5712 } 5713 --_nParked ; 5714 if (_Event >= 0) { 5715 ret = OS_OK; 5716 } 5717 _Event = 0 ; 5718 status = pthread_mutex_unlock(_mutex); 5719 assert_status(status == 0, status, "mutex_unlock"); 5720 assert (_nParked == 0, "invariant") ; 5721 // Paranoia to ensure our locked and lock-free paths interact 5722 // correctly with each other. 5723 OrderAccess::fence(); 5724 return ret; 5725 } 5726 5727 void os::PlatformEvent::unpark() { 5728 // Transitions for _Event: 5729 // 0 :=> 1 5730 // 1 :=> 1 5731 // -1 :=> either 0 or 1; must signal target thread 5732 // That is, we can safely transition _Event from -1 to either 5733 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back 5734 // unpark() calls. 5735 // See also: "Semaphores in Plan 9" by Mullender & Cox 5736 // 5737 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5738 // that it will take two back-to-back park() calls for the owning 5739 // thread to block. This has the benefit of forcing a spurious return 5740 // from the first park() call after an unpark() call which will help 5741 // shake out uses of park() and unpark() without condition variables. 5742 5743 if (Atomic::xchg(1, &_Event) >= 0) return; 5744 5745 // Wait for the thread associated with the event to vacate 5746 int status = pthread_mutex_lock(_mutex); 5747 assert_status(status == 0, status, "mutex_lock"); 5748 int AnyWaiters = _nParked; 5749 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5750 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5751 AnyWaiters = 0; 5752 pthread_cond_signal(_cond); 5753 } 5754 status = pthread_mutex_unlock(_mutex); 5755 assert_status(status == 0, status, "mutex_unlock"); 5756 if (AnyWaiters != 0) { 5757 status = pthread_cond_signal(_cond); 5758 assert_status(status == 0, status, "cond_signal"); 5759 } 5760 5761 // Note that we signal() _after dropping the lock for "immortal" Events. 5762 // This is safe and avoids a common class of futile wakeups. In rare 5763 // circumstances this can cause a thread to return prematurely from 5764 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 5765 // simply re-test the condition and re-park itself. 5766 } 5767 5768 5769 // JSR166 5770 // ------------------------------------------------------- 5771 5772 /* 5773 * The solaris and linux implementations of park/unpark are fairly 5774 * conservative for now, but can be improved. They currently use a 5775 * mutex/condvar pair, plus a a count. 5776 * Park decrements count if > 0, else does a condvar wait. Unpark 5777 * sets count to 1 and signals condvar. Only one thread ever waits 5778 * on the condvar. Contention seen when trying to park implies that someone 5779 * is unparking you, so don't wait. And spurious returns are fine, so there 5780 * is no need to track notifications. 5781 */ 5782 5783 /* 5784 * This code is common to linux and solaris and will be moved to a 5785 * common place in dolphin. 5786 * 5787 * The passed in time value is either a relative time in nanoseconds 5788 * or an absolute time in milliseconds. Either way it has to be unpacked 5789 * into suitable seconds and nanoseconds components and stored in the 5790 * given timespec structure. 5791 * Given time is a 64-bit value and the time_t used in the timespec is only 5792 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 5793 * overflow if times way in the future are given. Further on Solaris versions 5794 * prior to 10 there is a restriction (see cond_timedwait) that the specified 5795 * number of seconds, in abstime, is less than current_time + 100,000,000. 5796 * As it will be 28 years before "now + 100000000" will overflow we can 5797 * ignore overflow and just impose a hard-limit on seconds using the value 5798 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 5799 * years from "now". 5800 */ 5801 5802 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5803 assert (time > 0, "convertTime"); 5804 time_t max_secs = 0; 5805 5806 if (!os::Linux::supports_monotonic_clock() || isAbsolute) { 5807 struct timeval now; 5808 int status = gettimeofday(&now, NULL); 5809 assert(status == 0, "gettimeofday"); 5810 5811 max_secs = now.tv_sec + MAX_SECS; 5812 5813 if (isAbsolute) { 5814 jlong secs = time / 1000; 5815 if (secs > max_secs) { 5816 absTime->tv_sec = max_secs; 5817 } else { 5818 absTime->tv_sec = secs; 5819 } 5820 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5821 } else { 5822 jlong secs = time / NANOSECS_PER_SEC; 5823 if (secs >= MAX_SECS) { 5824 absTime->tv_sec = max_secs; 5825 absTime->tv_nsec = 0; 5826 } else { 5827 absTime->tv_sec = now.tv_sec + secs; 5828 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5829 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5830 absTime->tv_nsec -= NANOSECS_PER_SEC; 5831 ++absTime->tv_sec; // note: this must be <= max_secs 5832 } 5833 } 5834 } 5835 } else { 5836 // must be relative using monotonic clock 5837 struct timespec now; 5838 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5839 assert_status(status == 0, status, "clock_gettime"); 5840 max_secs = now.tv_sec + MAX_SECS; 5841 jlong secs = time / NANOSECS_PER_SEC; 5842 if (secs >= MAX_SECS) { 5843 absTime->tv_sec = max_secs; 5844 absTime->tv_nsec = 0; 5845 } else { 5846 absTime->tv_sec = now.tv_sec + secs; 5847 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5848 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5849 absTime->tv_nsec -= NANOSECS_PER_SEC; 5850 ++absTime->tv_sec; // note: this must be <= max_secs 5851 } 5852 } 5853 } 5854 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5855 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5856 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5857 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5858 } 5859 5860 void Parker::park(bool isAbsolute, jlong time) { 5861 // Ideally we'd do something useful while spinning, such 5862 // as calling unpackTime(). 5863 5864 // Optional fast-path check: 5865 // Return immediately if a permit is available. 5866 // We depend on Atomic::xchg() having full barrier semantics 5867 // since we are doing a lock-free update to _counter. 5868 if (Atomic::xchg(0, &_counter) > 0) return; 5869 5870 Thread* thread = Thread::current(); 5871 assert(thread->is_Java_thread(), "Must be JavaThread"); 5872 JavaThread *jt = (JavaThread *)thread; 5873 5874 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5875 // Check interrupt before trying to wait 5876 if (Thread::is_interrupted(thread, false)) { 5877 return; 5878 } 5879 5880 // Next, demultiplex/decode time arguments 5881 timespec absTime; 5882 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all 5883 return; 5884 } 5885 if (time > 0) { 5886 unpackTime(&absTime, isAbsolute, time); 5887 } 5888 5889 5890 // Enter safepoint region 5891 // Beware of deadlocks such as 6317397. 5892 // The per-thread Parker:: mutex is a classic leaf-lock. 5893 // In particular a thread must never block on the Threads_lock while 5894 // holding the Parker:: mutex. If safepoints are pending both the 5895 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5896 ThreadBlockInVM tbivm(jt); 5897 5898 // Don't wait if cannot get lock since interference arises from 5899 // unblocking. Also. check interrupt before trying wait 5900 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5901 return; 5902 } 5903 5904 int status ; 5905 if (_counter > 0) { // no wait needed 5906 _counter = 0; 5907 status = pthread_mutex_unlock(_mutex); 5908 assert (status == 0, "invariant") ; 5909 // Paranoia to ensure our locked and lock-free paths interact 5910 // correctly with each other and Java-level accesses. 5911 OrderAccess::fence(); 5912 return; 5913 } 5914 5915 #ifdef ASSERT 5916 // Don't catch signals while blocked; let the running threads have the signals. 5917 // (This allows a debugger to break into the running thread.) 5918 sigset_t oldsigs; 5919 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5920 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5921 #endif 5922 5923 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5924 jt->set_suspend_equivalent(); 5925 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5926 5927 assert(_cur_index == -1, "invariant"); 5928 if (time == 0) { 5929 _cur_index = REL_INDEX; // arbitrary choice when not timed 5930 status = pthread_cond_wait (&_cond[_cur_index], _mutex) ; 5931 } else { 5932 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5933 status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ; 5934 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5935 pthread_cond_destroy (&_cond[_cur_index]) ; 5936 pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5937 } 5938 } 5939 _cur_index = -1; 5940 assert_status(status == 0 || status == EINTR || 5941 status == ETIME || status == ETIMEDOUT, 5942 status, "cond_timedwait"); 5943 5944 #ifdef ASSERT 5945 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5946 #endif 5947 5948 _counter = 0 ; 5949 status = pthread_mutex_unlock(_mutex) ; 5950 assert_status(status == 0, status, "invariant") ; 5951 // Paranoia to ensure our locked and lock-free paths interact 5952 // correctly with each other and Java-level accesses. 5953 OrderAccess::fence(); 5954 5955 // If externally suspended while waiting, re-suspend 5956 if (jt->handle_special_suspend_equivalent_condition()) { 5957 jt->java_suspend_self(); 5958 } 5959 } 5960 5961 void Parker::unpark() { 5962 int s, status ; 5963 status = pthread_mutex_lock(_mutex); 5964 assert (status == 0, "invariant") ; 5965 s = _counter; 5966 _counter = 1; 5967 if (s < 1) { 5968 // thread might be parked 5969 if (_cur_index != -1) { 5970 // thread is definitely parked 5971 if (WorkAroundNPTLTimedWaitHang) { 5972 status = pthread_cond_signal (&_cond[_cur_index]); 5973 assert (status == 0, "invariant"); 5974 status = pthread_mutex_unlock(_mutex); 5975 assert (status == 0, "invariant"); 5976 } else { 5977 status = pthread_mutex_unlock(_mutex); 5978 assert (status == 0, "invariant"); 5979 status = pthread_cond_signal (&_cond[_cur_index]); 5980 assert (status == 0, "invariant"); 5981 } 5982 } else { 5983 pthread_mutex_unlock(_mutex); 5984 assert (status == 0, "invariant") ; 5985 } 5986 } else { 5987 pthread_mutex_unlock(_mutex); 5988 assert (status == 0, "invariant") ; 5989 } 5990 } 5991 5992 5993 extern char** environ; 5994 5995 #ifndef __NR_fork 5996 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5997 #endif 5998 5999 #ifndef __NR_execve 6000 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 6001 #endif 6002 6003 // Run the specified command in a separate process. Return its exit value, 6004 // or -1 on failure (e.g. can't fork a new process). 6005 // Unlike system(), this function can be called from signal handler. It 6006 // doesn't block SIGINT et al. 6007 int os::fork_and_exec(char* cmd) { 6008 const char * argv[4] = {"sh", "-c", cmd, NULL}; 6009 6010 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 6011 // pthread_atfork handlers and reset pthread library. All we need is a 6012 // separate process to execve. Make a direct syscall to fork process. 6013 // On IA64 there's no fork syscall, we have to use fork() and hope for 6014 // the best... 6015 pid_t pid = NOT_IA64(syscall(__NR_fork);) 6016 IA64_ONLY(fork();) 6017 6018 if (pid < 0) { 6019 // fork failed 6020 return -1; 6021 6022 } else if (pid == 0) { 6023 // child process 6024 6025 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 6026 // first to kill every thread on the thread list. Because this list is 6027 // not reset by fork() (see notes above), execve() will instead kill 6028 // every thread in the parent process. We know this is the only thread 6029 // in the new process, so make a system call directly. 6030 // IA64 should use normal execve() from glibc to match the glibc fork() 6031 // above. 6032 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 6033 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 6034 6035 // execve failed 6036 _exit(-1); 6037 6038 } else { 6039 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 6040 // care about the actual exit code, for now. 6041 6042 int status; 6043 6044 // Wait for the child process to exit. This returns immediately if 6045 // the child has already exited. */ 6046 while (waitpid(pid, &status, 0) < 0) { 6047 switch (errno) { 6048 case ECHILD: return 0; 6049 case EINTR: break; 6050 default: return -1; 6051 } 6052 } 6053 6054 if (WIFEXITED(status)) { 6055 // The child exited normally; get its exit code. 6056 return WEXITSTATUS(status); 6057 } else if (WIFSIGNALED(status)) { 6058 // The child exited because of a signal 6059 // The best value to return is 0x80 + signal number, 6060 // because that is what all Unix shells do, and because 6061 // it allows callers to distinguish between process exit and 6062 // process death by signal. 6063 return 0x80 + WTERMSIG(status); 6064 } else { 6065 // Unknown exit code; pass it through 6066 return status; 6067 } 6068 } 6069 } 6070 6071 // is_headless_jre() 6072 // 6073 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 6074 // in order to report if we are running in a headless jre 6075 // 6076 // Since JDK8 xawt/libmawt.so was moved into the same directory 6077 // as libawt.so, and renamed libawt_xawt.so 6078 // 6079 bool os::is_headless_jre() { 6080 struct stat statbuf; 6081 char buf[MAXPATHLEN]; 6082 char libmawtpath[MAXPATHLEN]; 6083 const char *xawtstr = "/xawt/libmawt.so"; 6084 const char *new_xawtstr = "/libawt_xawt.so"; 6085 char *p; 6086 6087 // Get path to libjvm.so 6088 os::jvm_path(buf, sizeof(buf)); 6089 6090 // Get rid of libjvm.so 6091 p = strrchr(buf, '/'); 6092 if (p == NULL) return false; 6093 else *p = '\0'; 6094 6095 // Get rid of client or server 6096 p = strrchr(buf, '/'); 6097 if (p == NULL) return false; 6098 else *p = '\0'; 6099 6100 // check xawt/libmawt.so 6101 strcpy(libmawtpath, buf); 6102 strcat(libmawtpath, xawtstr); 6103 if (::stat(libmawtpath, &statbuf) == 0) return false; 6104 6105 // check libawt_xawt.so 6106 strcpy(libmawtpath, buf); 6107 strcat(libmawtpath, new_xawtstr); 6108 if (::stat(libmawtpath, &statbuf) == 0) return false; 6109 6110 return true; 6111 } 6112 6113 // Get the default path to the core file 6114 // Returns the length of the string 6115 int os::get_core_path(char* buffer, size_t bufferSize) { 6116 const char* p = get_current_directory(buffer, bufferSize); 6117 6118 if (p == NULL) { 6119 assert(p != NULL, "failed to get current directory"); 6120 return 0; 6121 } 6122 6123 return strlen(buffer); 6124 } 6125 6126 #ifdef JAVASE_EMBEDDED 6127 // 6128 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory. 6129 // 6130 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL; 6131 6132 // ctor 6133 // 6134 MemNotifyThread::MemNotifyThread(int fd): Thread() { 6135 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread"); 6136 _fd = fd; 6137 6138 if (os::create_thread(this, os::os_thread)) { 6139 _memnotify_thread = this; 6140 os::set_priority(this, NearMaxPriority); 6141 os::start_thread(this); 6142 } 6143 } 6144 6145 // Where all the work gets done 6146 // 6147 void MemNotifyThread::run() { 6148 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread"); 6149 6150 // Set up the select arguments 6151 fd_set rfds; 6152 if (_fd != -1) { 6153 FD_ZERO(&rfds); 6154 FD_SET(_fd, &rfds); 6155 } 6156 6157 // Now wait for the mem_notify device to wake up 6158 while (1) { 6159 // Wait for the mem_notify device to signal us.. 6160 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL); 6161 if (rc == -1) { 6162 perror("select!\n"); 6163 break; 6164 } else if (rc) { 6165 //ssize_t free_before = os::available_memory(); 6166 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024); 6167 6168 // The kernel is telling us there is not much memory left... 6169 // try to do something about that 6170 6171 // If we are not already in a GC, try one. 6172 if (!Universe::heap()->is_gc_active()) { 6173 Universe::heap()->collect(GCCause::_allocation_failure); 6174 6175 //ssize_t free_after = os::available_memory(); 6176 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024); 6177 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024); 6178 } 6179 // We might want to do something like the following if we find the GC's are not helping... 6180 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true); 6181 } 6182 } 6183 } 6184 6185 // 6186 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it. 6187 // 6188 void MemNotifyThread::start() { 6189 int fd; 6190 fd = open ("/dev/mem_notify", O_RDONLY, 0); 6191 if (fd < 0) { 6192 return; 6193 } 6194 6195 if (memnotify_thread() == NULL) { 6196 new MemNotifyThread(fd); 6197 } 6198 } 6199 6200 #endif // JAVASE_EMBEDDED 6201 6202 6203 /////////////// Unit tests /////////////// 6204 6205 #ifndef PRODUCT 6206 6207 #define test_log(...) \ 6208 do {\ 6209 if (VerboseInternalVMTests) { \ 6210 tty->print_cr(__VA_ARGS__); \ 6211 tty->flush(); \ 6212 }\ 6213 } while (false) 6214 6215 class TestReserveMemorySpecial : AllStatic { 6216 public: 6217 static void small_page_write(void* addr, size_t size) { 6218 size_t page_size = os::vm_page_size(); 6219 6220 char* end = (char*)addr + size; 6221 for (char* p = (char*)addr; p < end; p += page_size) { 6222 *p = 1; 6223 } 6224 } 6225 6226 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6227 if (!UseHugeTLBFS) { 6228 return; 6229 } 6230 6231 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6232 6233 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6234 6235 if (addr != NULL) { 6236 small_page_write(addr, size); 6237 6238 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6239 } 6240 } 6241 6242 static void test_reserve_memory_special_huge_tlbfs_only() { 6243 if (!UseHugeTLBFS) { 6244 return; 6245 } 6246 6247 size_t lp = os::large_page_size(); 6248 6249 for (size_t size = lp; size <= lp * 10; size += lp) { 6250 test_reserve_memory_special_huge_tlbfs_only(size); 6251 } 6252 } 6253 6254 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) { 6255 if (!UseHugeTLBFS) { 6256 return; 6257 } 6258 6259 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")", 6260 size, alignment); 6261 6262 assert(size >= os::large_page_size(), "Incorrect input to test"); 6263 6264 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6265 6266 if (addr != NULL) { 6267 small_page_write(addr, size); 6268 6269 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6270 } 6271 } 6272 6273 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) { 6274 size_t lp = os::large_page_size(); 6275 size_t ag = os::vm_allocation_granularity(); 6276 6277 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6278 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment); 6279 } 6280 } 6281 6282 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6283 size_t lp = os::large_page_size(); 6284 size_t ag = os::vm_allocation_granularity(); 6285 6286 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp); 6287 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag); 6288 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2); 6289 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2); 6290 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag); 6291 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag); 6292 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2); 6293 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10); 6294 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2); 6295 } 6296 6297 static void test_reserve_memory_special_huge_tlbfs() { 6298 if (!UseHugeTLBFS) { 6299 return; 6300 } 6301 6302 test_reserve_memory_special_huge_tlbfs_only(); 6303 test_reserve_memory_special_huge_tlbfs_mixed(); 6304 } 6305 6306 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6307 if (!UseSHM) { 6308 return; 6309 } 6310 6311 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6312 6313 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6314 6315 if (addr != NULL) { 6316 assert(is_ptr_aligned(addr, alignment), "Check"); 6317 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6318 6319 small_page_write(addr, size); 6320 6321 os::Linux::release_memory_special_shm(addr, size); 6322 } 6323 } 6324 6325 static void test_reserve_memory_special_shm() { 6326 size_t lp = os::large_page_size(); 6327 size_t ag = os::vm_allocation_granularity(); 6328 6329 for (size_t size = ag; size < lp * 3; size += ag) { 6330 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6331 test_reserve_memory_special_shm(size, alignment); 6332 } 6333 } 6334 } 6335 6336 static void test() { 6337 test_reserve_memory_special_huge_tlbfs(); 6338 test_reserve_memory_special_shm(); 6339 } 6340 }; 6341 6342 void TestReserveMemorySpecial_test() { 6343 TestReserveMemorySpecial::test(); 6344 } 6345 6346 #endif