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/atomic.inline.hpp" 45 #include "runtime/extendedPC.hpp" 46 #include "runtime/globals.hpp" 47 #include "runtime/interfaceSupport.hpp" 48 #include "runtime/init.hpp" 49 #include "runtime/java.hpp" 50 #include "runtime/javaCalls.hpp" 51 #include "runtime/mutexLocker.hpp" 52 #include "runtime/objectMonitor.hpp" 53 #include "runtime/orderAccess.inline.hpp" 54 #include "runtime/osThread.hpp" 55 #include "runtime/perfMemory.hpp" 56 #include "runtime/sharedRuntime.hpp" 57 #include "runtime/statSampler.hpp" 58 #include "runtime/stubRoutines.hpp" 59 #include "runtime/thread.inline.hpp" 60 #include "runtime/threadCritical.hpp" 61 #include "runtime/timer.hpp" 62 #include "services/attachListener.hpp" 63 #include "services/memTracker.hpp" 64 #include "services/runtimeService.hpp" 65 #include "utilities/decoder.hpp" 66 #include "utilities/defaultStream.hpp" 67 #include "utilities/events.hpp" 68 #include "utilities/elfFile.hpp" 69 #include "utilities/growableArray.hpp" 70 #include "utilities/vmError.hpp" 71 72 // put OS-includes here 73 # include <sys/types.h> 74 # include <sys/mman.h> 75 # include <sys/stat.h> 76 # include <sys/select.h> 77 # include <pthread.h> 78 # include <signal.h> 79 # include <errno.h> 80 # include <dlfcn.h> 81 # include <stdio.h> 82 # include <unistd.h> 83 # include <sys/resource.h> 84 # include <pthread.h> 85 # include <sys/stat.h> 86 # include <sys/time.h> 87 # include <sys/times.h> 88 # include <sys/utsname.h> 89 # include <sys/socket.h> 90 # include <sys/wait.h> 91 # include <pwd.h> 92 # include <poll.h> 93 # include <semaphore.h> 94 # include <fcntl.h> 95 # include <string.h> 96 # include <syscall.h> 97 # include <sys/sysinfo.h> 98 # include <gnu/libc-version.h> 99 # include <sys/ipc.h> 100 # include <sys/shm.h> 101 # include <link.h> 102 # include <stdint.h> 103 # include <inttypes.h> 104 # include <sys/ioctl.h> 105 106 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 107 108 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling 109 // getrusage() is prepared to handle the associated failure. 110 #ifndef RUSAGE_THREAD 111 #define RUSAGE_THREAD (1) /* only the calling thread */ 112 #endif 113 114 #define MAX_PATH (2 * K) 115 116 #define MAX_SECS 100000000 117 118 // for timer info max values which include all bits 119 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 120 121 #define LARGEPAGES_BIT (1 << 6) 122 //////////////////////////////////////////////////////////////////////////////// 123 // global variables 124 julong os::Linux::_physical_memory = 0; 125 126 address os::Linux::_initial_thread_stack_bottom = NULL; 127 uintptr_t os::Linux::_initial_thread_stack_size = 0; 128 129 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 130 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 131 Mutex* os::Linux::_createThread_lock = NULL; 132 pthread_t os::Linux::_main_thread; 133 int os::Linux::_page_size = -1; 134 const int os::Linux::_vm_default_page_size = (8 * K); 135 bool os::Linux::_is_floating_stack = false; 136 bool os::Linux::_is_NPTL = false; 137 bool os::Linux::_supports_fast_thread_cpu_time = false; 138 const char * os::Linux::_glibc_version = NULL; 139 const char * os::Linux::_libpthread_version = NULL; 140 pthread_condattr_t os::Linux::_condattr[1]; 141 142 static jlong initial_time_count=0; 143 144 static int clock_tics_per_sec = 100; 145 146 // For diagnostics to print a message once. see run_periodic_checks 147 static sigset_t check_signal_done; 148 static bool check_signals = true; 149 150 static pid_t _initial_pid = 0; 151 152 /* Signal number used to suspend/resume a thread */ 153 154 /* do not use any signal number less than SIGSEGV, see 4355769 */ 155 static int SR_signum = SIGUSR2; 156 sigset_t SR_sigset; 157 158 /* Used to protect dlsym() calls */ 159 static pthread_mutex_t dl_mutex; 160 161 // Declarations 162 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time); 163 164 #ifdef JAVASE_EMBEDDED 165 class MemNotifyThread: public Thread { 166 friend class VMStructs; 167 public: 168 virtual void run(); 169 170 private: 171 static MemNotifyThread* _memnotify_thread; 172 int _fd; 173 174 public: 175 176 // Constructor 177 MemNotifyThread(int fd); 178 179 // Tester 180 bool is_memnotify_thread() const { return true; } 181 182 // Printing 183 char* name() const { return (char*)"Linux MemNotify Thread"; } 184 185 // Returns the single instance of the MemNotifyThread 186 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; } 187 188 // Create and start the single instance of MemNotifyThread 189 static void start(); 190 }; 191 #endif // JAVASE_EMBEDDED 192 193 // utility functions 194 195 static int SR_initialize(); 196 197 julong os::available_memory() { 198 return Linux::available_memory(); 199 } 200 201 julong os::Linux::available_memory() { 202 // values in struct sysinfo are "unsigned long" 203 struct sysinfo si; 204 sysinfo(&si); 205 206 return (julong)si.freeram * si.mem_unit; 207 } 208 209 julong os::physical_memory() { 210 return Linux::physical_memory(); 211 } 212 213 //////////////////////////////////////////////////////////////////////////////// 214 // environment support 215 216 bool os::getenv(const char* name, char* buf, int len) { 217 const char* val = ::getenv(name); 218 if (val != NULL && strlen(val) < (size_t)len) { 219 strcpy(buf, val); 220 return true; 221 } 222 if (len > 0) buf[0] = 0; // return a null string 223 return false; 224 } 225 226 227 // Return true if user is running as root. 228 229 bool os::have_special_privileges() { 230 static bool init = false; 231 static bool privileges = false; 232 if (!init) { 233 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 234 init = true; 235 } 236 return privileges; 237 } 238 239 240 #ifndef SYS_gettid 241 // i386: 224, ia64: 1105, amd64: 186, sparc 143 242 #ifdef __ia64__ 243 #define SYS_gettid 1105 244 #elif __i386__ 245 #define SYS_gettid 224 246 #elif __amd64__ 247 #define SYS_gettid 186 248 #elif __sparc__ 249 #define SYS_gettid 143 250 #else 251 #error define gettid for the arch 252 #endif 253 #endif 254 255 // Cpu architecture string 256 #if defined(ZERO) 257 static char cpu_arch[] = ZERO_LIBARCH; 258 #elif defined(IA64) 259 static char cpu_arch[] = "ia64"; 260 #elif defined(IA32) 261 static char cpu_arch[] = "i386"; 262 #elif defined(AMD64) 263 static char cpu_arch[] = "amd64"; 264 #elif defined(ARM) 265 static char cpu_arch[] = "arm"; 266 #elif defined(PPC32) 267 static char cpu_arch[] = "ppc"; 268 #elif defined(PPC64) 269 static char cpu_arch[] = "ppc64"; 270 #elif defined(SPARC) 271 # ifdef _LP64 272 static char cpu_arch[] = "sparcv9"; 273 # else 274 static char cpu_arch[] = "sparc"; 275 # endif 276 #else 277 #error Add appropriate cpu_arch setting 278 #endif 279 280 281 // pid_t gettid() 282 // 283 // Returns the kernel thread id of the currently running thread. Kernel 284 // thread id is used to access /proc. 285 // 286 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 287 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 288 // 289 pid_t os::Linux::gettid() { 290 int rslt = syscall(SYS_gettid); 291 if (rslt == -1) { 292 // old kernel, no NPTL support 293 return getpid(); 294 } else { 295 return (pid_t)rslt; 296 } 297 } 298 299 // Most versions of linux have a bug where the number of processors are 300 // determined by looking at the /proc file system. In a chroot environment, 301 // the system call returns 1. This causes the VM to act as if it is 302 // a single processor and elide locking (see is_MP() call). 303 static bool unsafe_chroot_detected = false; 304 static const char *unstable_chroot_error = "/proc file system not found.\n" 305 "Java may be unstable running multithreaded in a chroot " 306 "environment on Linux when /proc filesystem is not mounted."; 307 308 void os::Linux::initialize_system_info() { 309 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 310 if (processor_count() == 1) { 311 pid_t pid = os::Linux::gettid(); 312 char fname[32]; 313 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 314 FILE *fp = fopen(fname, "r"); 315 if (fp == NULL) { 316 unsafe_chroot_detected = true; 317 } else { 318 fclose(fp); 319 } 320 } 321 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 322 assert(processor_count() > 0, "linux error"); 323 } 324 325 void os::init_system_properties_values() { 326 // The next steps are taken in the product version: 327 // 328 // Obtain the JAVA_HOME value from the location of libjvm.so. 329 // This library should be located at: 330 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 331 // 332 // If "/jre/lib/" appears at the right place in the path, then we 333 // assume libjvm.so is installed in a JDK and we use this path. 334 // 335 // Otherwise exit with message: "Could not create the Java virtual machine." 336 // 337 // The following extra steps are taken in the debugging version: 338 // 339 // If "/jre/lib/" does NOT appear at the right place in the path 340 // instead of exit check for $JAVA_HOME environment variable. 341 // 342 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 343 // then we append a fake suffix "hotspot/libjvm.so" to this path so 344 // it looks like libjvm.so is installed there 345 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 346 // 347 // Otherwise exit. 348 // 349 // Important note: if the location of libjvm.so changes this 350 // code needs to be changed accordingly. 351 352 // See ld(1): 353 // The linker uses the following search paths to locate required 354 // shared libraries: 355 // 1: ... 356 // ... 357 // 7: The default directories, normally /lib and /usr/lib. 358 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 359 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 360 #else 361 #define DEFAULT_LIBPATH "/lib:/usr/lib" 362 #endif 363 364 // Base path of extensions installed on the system. 365 #define SYS_EXT_DIR "/usr/java/packages" 366 #define EXTENSIONS_DIR "/lib/ext" 367 #define ENDORSED_DIR "/lib/endorsed" 368 369 // Buffer that fits several sprintfs. 370 // Note that the space for the colon and the trailing null are provided 371 // by the nulls included by the sizeof operator. 372 const size_t bufsize = 373 MAX3((size_t)MAXPATHLEN, // For dll_dir & friends. 374 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir 375 (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir 376 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 377 378 // sysclasspath, java_home, dll_dir 379 { 380 char *pslash; 381 os::jvm_path(buf, bufsize); 382 383 // Found the full path to libjvm.so. 384 // Now cut the path to <java_home>/jre if we can. 385 *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so. 386 pslash = strrchr(buf, '/'); 387 if (pslash != NULL) { 388 *pslash = '\0'; // Get rid of /{client|server|hotspot}. 389 } 390 Arguments::set_dll_dir(buf); 391 392 if (pslash != NULL) { 393 pslash = strrchr(buf, '/'); 394 if (pslash != NULL) { 395 *pslash = '\0'; // Get rid of /<arch>. 396 pslash = strrchr(buf, '/'); 397 if (pslash != NULL) { 398 *pslash = '\0'; // Get rid of /lib. 399 } 400 } 401 } 402 Arguments::set_java_home(buf); 403 set_boot_path('/', ':'); 404 } 405 406 // Where to look for native libraries. 407 // 408 // Note: Due to a legacy implementation, most of the library path 409 // is set in the launcher. This was to accomodate linking restrictions 410 // on legacy Linux implementations (which are no longer supported). 411 // Eventually, all the library path setting will be done here. 412 // 413 // However, to prevent the proliferation of improperly built native 414 // libraries, the new path component /usr/java/packages is added here. 415 // Eventually, all the library path setting will be done here. 416 { 417 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It 418 // should always exist (until the legacy problem cited above is 419 // addressed). 420 const char *v = ::getenv("LD_LIBRARY_PATH"); 421 const char *v_colon = ":"; 422 if (v == NULL) { v = ""; v_colon = ""; } 423 // That's +1 for the colon and +1 for the trailing '\0'. 424 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char, 425 strlen(v) + 1 + 426 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1, 427 mtInternal); 428 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch); 429 Arguments::set_library_path(ld_library_path); 430 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal); 431 } 432 433 // Extensions directories. 434 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home()); 435 Arguments::set_ext_dirs(buf); 436 437 // Endorsed standards default directory. 438 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 439 Arguments::set_endorsed_dirs(buf); 440 441 FREE_C_HEAP_ARRAY(char, buf, mtInternal); 442 443 #undef DEFAULT_LIBPATH 444 #undef SYS_EXT_DIR 445 #undef EXTENSIONS_DIR 446 #undef ENDORSED_DIR 447 } 448 449 //////////////////////////////////////////////////////////////////////////////// 450 // breakpoint support 451 452 void os::breakpoint() { 453 BREAKPOINT; 454 } 455 456 extern "C" void breakpoint() { 457 // use debugger to set breakpoint here 458 } 459 460 //////////////////////////////////////////////////////////////////////////////// 461 // signal support 462 463 debug_only(static bool signal_sets_initialized = false); 464 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 465 466 bool os::Linux::is_sig_ignored(int sig) { 467 struct sigaction oact; 468 sigaction(sig, (struct sigaction*)NULL, &oact); 469 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 470 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 471 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 472 return true; 473 else 474 return false; 475 } 476 477 void os::Linux::signal_sets_init() { 478 // Should also have an assertion stating we are still single-threaded. 479 assert(!signal_sets_initialized, "Already initialized"); 480 // Fill in signals that are necessarily unblocked for all threads in 481 // the VM. Currently, we unblock the following signals: 482 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 483 // by -Xrs (=ReduceSignalUsage)); 484 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 485 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 486 // the dispositions or masks wrt these signals. 487 // Programs embedding the VM that want to use the above signals for their 488 // own purposes must, at this time, use the "-Xrs" option to prevent 489 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 490 // (See bug 4345157, and other related bugs). 491 // In reality, though, unblocking these signals is really a nop, since 492 // these signals are not blocked by default. 493 sigemptyset(&unblocked_sigs); 494 sigemptyset(&allowdebug_blocked_sigs); 495 sigaddset(&unblocked_sigs, SIGILL); 496 sigaddset(&unblocked_sigs, SIGSEGV); 497 sigaddset(&unblocked_sigs, SIGBUS); 498 sigaddset(&unblocked_sigs, SIGFPE); 499 #if defined(PPC64) 500 sigaddset(&unblocked_sigs, SIGTRAP); 501 #endif 502 sigaddset(&unblocked_sigs, SR_signum); 503 504 if (!ReduceSignalUsage) { 505 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 506 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 507 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 508 } 509 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 510 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 511 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 512 } 513 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 514 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 515 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 516 } 517 } 518 // Fill in signals that are blocked by all but the VM thread. 519 sigemptyset(&vm_sigs); 520 if (!ReduceSignalUsage) 521 sigaddset(&vm_sigs, BREAK_SIGNAL); 522 debug_only(signal_sets_initialized = true); 523 524 } 525 526 // These are signals that are unblocked while a thread is running Java. 527 // (For some reason, they get blocked by default.) 528 sigset_t* os::Linux::unblocked_signals() { 529 assert(signal_sets_initialized, "Not initialized"); 530 return &unblocked_sigs; 531 } 532 533 // These are the signals that are blocked while a (non-VM) thread is 534 // running Java. Only the VM thread handles these signals. 535 sigset_t* os::Linux::vm_signals() { 536 assert(signal_sets_initialized, "Not initialized"); 537 return &vm_sigs; 538 } 539 540 // These are signals that are blocked during cond_wait to allow debugger in 541 sigset_t* os::Linux::allowdebug_blocked_signals() { 542 assert(signal_sets_initialized, "Not initialized"); 543 return &allowdebug_blocked_sigs; 544 } 545 546 void os::Linux::hotspot_sigmask(Thread* thread) { 547 548 //Save caller's signal mask before setting VM signal mask 549 sigset_t caller_sigmask; 550 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 551 552 OSThread* osthread = thread->osthread(); 553 osthread->set_caller_sigmask(caller_sigmask); 554 555 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 556 557 if (!ReduceSignalUsage) { 558 if (thread->is_VM_thread()) { 559 // Only the VM thread handles BREAK_SIGNAL ... 560 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 561 } else { 562 // ... all other threads block BREAK_SIGNAL 563 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 564 } 565 } 566 } 567 568 ////////////////////////////////////////////////////////////////////////////// 569 // detecting pthread library 570 571 void os::Linux::libpthread_init() { 572 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 573 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 574 // generic name for earlier versions. 575 // Define macros here so we can build HotSpot on old systems. 576 # ifndef _CS_GNU_LIBC_VERSION 577 # define _CS_GNU_LIBC_VERSION 2 578 # endif 579 # ifndef _CS_GNU_LIBPTHREAD_VERSION 580 # define _CS_GNU_LIBPTHREAD_VERSION 3 581 # endif 582 583 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 584 if (n > 0) { 585 char *str = (char *)malloc(n, mtInternal); 586 confstr(_CS_GNU_LIBC_VERSION, str, n); 587 os::Linux::set_glibc_version(str); 588 } else { 589 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 590 static char _gnu_libc_version[32]; 591 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 592 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 593 os::Linux::set_glibc_version(_gnu_libc_version); 594 } 595 596 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 597 if (n > 0) { 598 char *str = (char *)malloc(n, mtInternal); 599 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 600 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 601 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 602 // is the case. LinuxThreads has a hard limit on max number of threads. 603 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 604 // On the other hand, NPTL does not have such a limit, sysconf() 605 // will return -1 and errno is not changed. Check if it is really NPTL. 606 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 607 strstr(str, "NPTL") && 608 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 609 free(str); 610 os::Linux::set_libpthread_version("linuxthreads"); 611 } else { 612 os::Linux::set_libpthread_version(str); 613 } 614 } else { 615 // glibc before 2.3.2 only has LinuxThreads. 616 os::Linux::set_libpthread_version("linuxthreads"); 617 } 618 619 if (strstr(libpthread_version(), "NPTL")) { 620 os::Linux::set_is_NPTL(); 621 } else { 622 os::Linux::set_is_LinuxThreads(); 623 } 624 625 // LinuxThreads have two flavors: floating-stack mode, which allows variable 626 // stack size; and fixed-stack mode. NPTL is always floating-stack. 627 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 628 os::Linux::set_is_floating_stack(); 629 } 630 } 631 632 ///////////////////////////////////////////////////////////////////////////// 633 // thread stack 634 635 // Force Linux kernel to expand current thread stack. If "bottom" is close 636 // to the stack guard, caller should block all signals. 637 // 638 // MAP_GROWSDOWN: 639 // A special mmap() flag that is used to implement thread stacks. It tells 640 // kernel that the memory region should extend downwards when needed. This 641 // allows early versions of LinuxThreads to only mmap the first few pages 642 // when creating a new thread. Linux kernel will automatically expand thread 643 // stack as needed (on page faults). 644 // 645 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 646 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 647 // region, it's hard to tell if the fault is due to a legitimate stack 648 // access or because of reading/writing non-exist memory (e.g. buffer 649 // overrun). As a rule, if the fault happens below current stack pointer, 650 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 651 // application (see Linux kernel fault.c). 652 // 653 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 654 // stack overflow detection. 655 // 656 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 657 // not use this flag. However, the stack of initial thread is not created 658 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 659 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 660 // and then attach the thread to JVM. 661 // 662 // To get around the problem and allow stack banging on Linux, we need to 663 // manually expand thread stack after receiving the SIGSEGV. 664 // 665 // There are two ways to expand thread stack to address "bottom", we used 666 // both of them in JVM before 1.5: 667 // 1. adjust stack pointer first so that it is below "bottom", and then 668 // touch "bottom" 669 // 2. mmap() the page in question 670 // 671 // Now alternate signal stack is gone, it's harder to use 2. For instance, 672 // if current sp is already near the lower end of page 101, and we need to 673 // call mmap() to map page 100, it is possible that part of the mmap() frame 674 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 675 // That will destroy the mmap() frame and cause VM to crash. 676 // 677 // The following code works by adjusting sp first, then accessing the "bottom" 678 // page to force a page fault. Linux kernel will then automatically expand the 679 // stack mapping. 680 // 681 // _expand_stack_to() assumes its frame size is less than page size, which 682 // should always be true if the function is not inlined. 683 684 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 685 #define NOINLINE 686 #else 687 #define NOINLINE __attribute__ ((noinline)) 688 #endif 689 690 static void _expand_stack_to(address bottom) NOINLINE; 691 692 static void _expand_stack_to(address bottom) { 693 address sp; 694 size_t size; 695 volatile char *p; 696 697 // Adjust bottom to point to the largest address within the same page, it 698 // gives us a one-page buffer if alloca() allocates slightly more memory. 699 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 700 bottom += os::Linux::page_size() - 1; 701 702 // sp might be slightly above current stack pointer; if that's the case, we 703 // will alloca() a little more space than necessary, which is OK. Don't use 704 // os::current_stack_pointer(), as its result can be slightly below current 705 // stack pointer, causing us to not alloca enough to reach "bottom". 706 sp = (address)&sp; 707 708 if (sp > bottom) { 709 size = sp - bottom; 710 p = (volatile char *)alloca(size); 711 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 712 p[0] = '\0'; 713 } 714 } 715 716 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 717 assert(t!=NULL, "just checking"); 718 assert(t->osthread()->expanding_stack(), "expand should be set"); 719 assert(t->stack_base() != NULL, "stack_base was not initialized"); 720 721 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 722 sigset_t mask_all, old_sigset; 723 sigfillset(&mask_all); 724 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 725 _expand_stack_to(addr); 726 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 727 return true; 728 } 729 return false; 730 } 731 732 ////////////////////////////////////////////////////////////////////////////// 733 // create new thread 734 735 static address highest_vm_reserved_address(); 736 737 // check if it's safe to start a new thread 738 static bool _thread_safety_check(Thread* thread) { 739 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 740 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 741 // Heap is mmap'ed at lower end of memory space. Thread stacks are 742 // allocated (MAP_FIXED) from high address space. Every thread stack 743 // occupies a fixed size slot (usually 2Mbytes, but user can change 744 // it to other values if they rebuild LinuxThreads). 745 // 746 // Problem with MAP_FIXED is that mmap() can still succeed even part of 747 // the memory region has already been mmap'ed. That means if we have too 748 // many threads and/or very large heap, eventually thread stack will 749 // collide with heap. 750 // 751 // Here we try to prevent heap/stack collision by comparing current 752 // stack bottom with the highest address that has been mmap'ed by JVM 753 // plus a safety margin for memory maps created by native code. 754 // 755 // This feature can be disabled by setting ThreadSafetyMargin to 0 756 // 757 if (ThreadSafetyMargin > 0) { 758 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 759 760 // not safe if our stack extends below the safety margin 761 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 762 } else { 763 return true; 764 } 765 } else { 766 // Floating stack LinuxThreads or NPTL: 767 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 768 // there's not enough space left, pthread_create() will fail. If we come 769 // here, that means enough space has been reserved for stack. 770 return true; 771 } 772 } 773 774 // Thread start routine for all newly created threads 775 static void *java_start(Thread *thread) { 776 // Try to randomize the cache line index of hot stack frames. 777 // This helps when threads of the same stack traces evict each other's 778 // cache lines. The threads can be either from the same JVM instance, or 779 // from different JVM instances. The benefit is especially true for 780 // processors with hyperthreading technology. 781 static int counter = 0; 782 int pid = os::current_process_id(); 783 alloca(((pid ^ counter++) & 7) * 128); 784 785 ThreadLocalStorage::set_thread(thread); 786 787 OSThread* osthread = thread->osthread(); 788 Monitor* sync = osthread->startThread_lock(); 789 790 // non floating stack LinuxThreads needs extra check, see above 791 if (!_thread_safety_check(thread)) { 792 // notify parent thread 793 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 794 osthread->set_state(ZOMBIE); 795 sync->notify_all(); 796 return NULL; 797 } 798 799 // thread_id is kernel thread id (similar to Solaris LWP id) 800 osthread->set_thread_id(os::Linux::gettid()); 801 802 if (UseNUMA) { 803 int lgrp_id = os::numa_get_group_id(); 804 if (lgrp_id != -1) { 805 thread->set_lgrp_id(lgrp_id); 806 } 807 } 808 // initialize signal mask for this thread 809 os::Linux::hotspot_sigmask(thread); 810 811 // initialize floating point control register 812 os::Linux::init_thread_fpu_state(); 813 814 // handshaking with parent thread 815 { 816 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 817 818 // notify parent thread 819 osthread->set_state(INITIALIZED); 820 sync->notify_all(); 821 822 // wait until os::start_thread() 823 while (osthread->get_state() == INITIALIZED) { 824 sync->wait(Mutex::_no_safepoint_check_flag); 825 } 826 } 827 828 // call one more level start routine 829 thread->run(); 830 831 return 0; 832 } 833 834 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 835 assert(thread->osthread() == NULL, "caller responsible"); 836 837 // Allocate the OSThread object 838 OSThread* osthread = new OSThread(NULL, NULL); 839 if (osthread == NULL) { 840 return false; 841 } 842 843 // set the correct thread state 844 osthread->set_thread_type(thr_type); 845 846 // Initial state is ALLOCATED but not INITIALIZED 847 osthread->set_state(ALLOCATED); 848 849 thread->set_osthread(osthread); 850 851 // init thread attributes 852 pthread_attr_t attr; 853 pthread_attr_init(&attr); 854 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 855 856 // stack size 857 if (os::Linux::supports_variable_stack_size()) { 858 // calculate stack size if it's not specified by caller 859 if (stack_size == 0) { 860 stack_size = os::Linux::default_stack_size(thr_type); 861 862 switch (thr_type) { 863 case os::java_thread: 864 // Java threads use ThreadStackSize which default value can be 865 // changed with the flag -Xss 866 assert(JavaThread::stack_size_at_create() > 0, "this should be set"); 867 stack_size = JavaThread::stack_size_at_create(); 868 break; 869 case os::compiler_thread: 870 if (CompilerThreadStackSize > 0) { 871 stack_size = (size_t)(CompilerThreadStackSize * K); 872 break; 873 } // else fall through: 874 // use VMThreadStackSize if CompilerThreadStackSize is not defined 875 case os::vm_thread: 876 case os::pgc_thread: 877 case os::cgc_thread: 878 case os::watcher_thread: 879 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 880 break; 881 } 882 } 883 884 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 885 pthread_attr_setstacksize(&attr, stack_size); 886 } else { 887 // let pthread_create() pick the default value. 888 } 889 890 // glibc guard page 891 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 892 893 ThreadState state; 894 895 { 896 // Serialize thread creation if we are running with fixed stack LinuxThreads 897 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 898 if (lock) { 899 os::Linux::createThread_lock()->lock_without_safepoint_check(); 900 } 901 902 pthread_t tid; 903 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 904 905 pthread_attr_destroy(&attr); 906 907 if (ret != 0) { 908 if (PrintMiscellaneous && (Verbose || WizardMode)) { 909 perror("pthread_create()"); 910 } 911 // Need to clean up stuff we've allocated so far 912 thread->set_osthread(NULL); 913 delete osthread; 914 if (lock) os::Linux::createThread_lock()->unlock(); 915 return false; 916 } 917 918 // Store pthread info into the OSThread 919 osthread->set_pthread_id(tid); 920 921 // Wait until child thread is either initialized or aborted 922 { 923 Monitor* sync_with_child = osthread->startThread_lock(); 924 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 925 while ((state = osthread->get_state()) == ALLOCATED) { 926 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 927 } 928 } 929 930 if (lock) { 931 os::Linux::createThread_lock()->unlock(); 932 } 933 } 934 935 // Aborted due to thread limit being reached 936 if (state == ZOMBIE) { 937 thread->set_osthread(NULL); 938 delete osthread; 939 return false; 940 } 941 942 // The thread is returned suspended (in state INITIALIZED), 943 // and is started higher up in the call chain 944 assert(state == INITIALIZED, "race condition"); 945 return true; 946 } 947 948 ///////////////////////////////////////////////////////////////////////////// 949 // attach existing thread 950 951 // bootstrap the main thread 952 bool os::create_main_thread(JavaThread* thread) { 953 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 954 return create_attached_thread(thread); 955 } 956 957 bool os::create_attached_thread(JavaThread* thread) { 958 #ifdef ASSERT 959 thread->verify_not_published(); 960 #endif 961 962 // Allocate the OSThread object 963 OSThread* osthread = new OSThread(NULL, NULL); 964 965 if (osthread == NULL) { 966 return false; 967 } 968 969 // Store pthread info into the OSThread 970 osthread->set_thread_id(os::Linux::gettid()); 971 osthread->set_pthread_id(::pthread_self()); 972 973 // initialize floating point control register 974 os::Linux::init_thread_fpu_state(); 975 976 // Initial thread state is RUNNABLE 977 osthread->set_state(RUNNABLE); 978 979 thread->set_osthread(osthread); 980 981 if (UseNUMA) { 982 int lgrp_id = os::numa_get_group_id(); 983 if (lgrp_id != -1) { 984 thread->set_lgrp_id(lgrp_id); 985 } 986 } 987 988 if (os::Linux::is_initial_thread()) { 989 // If current thread is initial thread, its stack is mapped on demand, 990 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 991 // the entire stack region to avoid SEGV in stack banging. 992 // It is also useful to get around the heap-stack-gap problem on SuSE 993 // kernel (see 4821821 for details). We first expand stack to the top 994 // of yellow zone, then enable stack yellow zone (order is significant, 995 // enabling yellow zone first will crash JVM on SuSE Linux), so there 996 // is no gap between the last two virtual memory regions. 997 998 JavaThread *jt = (JavaThread *)thread; 999 address addr = jt->stack_yellow_zone_base(); 1000 assert(addr != NULL, "initialization problem?"); 1001 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 1002 1003 osthread->set_expanding_stack(); 1004 os::Linux::manually_expand_stack(jt, addr); 1005 osthread->clear_expanding_stack(); 1006 } 1007 1008 // initialize signal mask for this thread 1009 // and save the caller's signal mask 1010 os::Linux::hotspot_sigmask(thread); 1011 1012 return true; 1013 } 1014 1015 void os::pd_start_thread(Thread* thread) { 1016 OSThread * osthread = thread->osthread(); 1017 assert(osthread->get_state() != INITIALIZED, "just checking"); 1018 Monitor* sync_with_child = osthread->startThread_lock(); 1019 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 1020 sync_with_child->notify(); 1021 } 1022 1023 // Free Linux resources related to the OSThread 1024 void os::free_thread(OSThread* osthread) { 1025 assert(osthread != NULL, "osthread not set"); 1026 1027 if (Thread::current()->osthread() == osthread) { 1028 // Restore caller's signal mask 1029 sigset_t sigmask = osthread->caller_sigmask(); 1030 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1031 } 1032 1033 delete osthread; 1034 } 1035 1036 ////////////////////////////////////////////////////////////////////////////// 1037 // thread local storage 1038 1039 // Restore the thread pointer if the destructor is called. This is in case 1040 // someone from JNI code sets up a destructor with pthread_key_create to run 1041 // detachCurrentThread on thread death. Unless we restore the thread pointer we 1042 // will hang or crash. When detachCurrentThread is called the key will be set 1043 // to null and we will not be called again. If detachCurrentThread is never 1044 // called we could loop forever depending on the pthread implementation. 1045 static void restore_thread_pointer(void* p) { 1046 Thread* thread = (Thread*) p; 1047 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); 1048 } 1049 1050 int os::allocate_thread_local_storage() { 1051 pthread_key_t key; 1052 int rslt = pthread_key_create(&key, restore_thread_pointer); 1053 assert(rslt == 0, "cannot allocate thread local storage"); 1054 return (int)key; 1055 } 1056 1057 // Note: This is currently not used by VM, as we don't destroy TLS key 1058 // on VM exit. 1059 void os::free_thread_local_storage(int index) { 1060 int rslt = pthread_key_delete((pthread_key_t)index); 1061 assert(rslt == 0, "invalid index"); 1062 } 1063 1064 void os::thread_local_storage_at_put(int index, void* value) { 1065 int rslt = pthread_setspecific((pthread_key_t)index, value); 1066 assert(rslt == 0, "pthread_setspecific failed"); 1067 } 1068 1069 extern "C" Thread* get_thread() { 1070 return ThreadLocalStorage::thread(); 1071 } 1072 1073 ////////////////////////////////////////////////////////////////////////////// 1074 // initial thread 1075 1076 // Check if current thread is the initial thread, similar to Solaris thr_main. 1077 bool os::Linux::is_initial_thread(void) { 1078 char dummy; 1079 // If called before init complete, thread stack bottom will be null. 1080 // Can be called if fatal error occurs before initialization. 1081 if (initial_thread_stack_bottom() == NULL) return false; 1082 assert(initial_thread_stack_bottom() != NULL && 1083 initial_thread_stack_size() != 0, 1084 "os::init did not locate initial thread's stack region"); 1085 if ((address)&dummy >= initial_thread_stack_bottom() && 1086 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1087 return true; 1088 else return false; 1089 } 1090 1091 // Find the virtual memory area that contains addr 1092 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1093 FILE *fp = fopen("/proc/self/maps", "r"); 1094 if (fp) { 1095 address low, high; 1096 while (!feof(fp)) { 1097 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1098 if (low <= addr && addr < high) { 1099 if (vma_low) *vma_low = low; 1100 if (vma_high) *vma_high = high; 1101 fclose(fp); 1102 return true; 1103 } 1104 } 1105 for (;;) { 1106 int ch = fgetc(fp); 1107 if (ch == EOF || ch == (int)'\n') break; 1108 } 1109 } 1110 fclose(fp); 1111 } 1112 return false; 1113 } 1114 1115 // Locate initial thread stack. This special handling of initial thread stack 1116 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1117 // bogus value for initial thread. 1118 void os::Linux::capture_initial_stack(size_t max_size) { 1119 // stack size is the easy part, get it from RLIMIT_STACK 1120 size_t stack_size; 1121 struct rlimit rlim; 1122 getrlimit(RLIMIT_STACK, &rlim); 1123 stack_size = rlim.rlim_cur; 1124 1125 // 6308388: a bug in ld.so will relocate its own .data section to the 1126 // lower end of primordial stack; reduce ulimit -s value a little bit 1127 // so we won't install guard page on ld.so's data section. 1128 stack_size -= 2 * page_size(); 1129 1130 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1131 // 7.1, in both cases we will get 2G in return value. 1132 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1133 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1134 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1135 // in case other parts in glibc still assumes 2M max stack size. 1136 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1137 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1138 if (stack_size > 2 * K * K IA64_ONLY(*2)) 1139 stack_size = 2 * K * K IA64_ONLY(*2); 1140 // Try to figure out where the stack base (top) is. This is harder. 1141 // 1142 // When an application is started, glibc saves the initial stack pointer in 1143 // a global variable "__libc_stack_end", which is then used by system 1144 // libraries. __libc_stack_end should be pretty close to stack top. The 1145 // variable is available since the very early days. However, because it is 1146 // a private interface, it could disappear in the future. 1147 // 1148 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1149 // to __libc_stack_end, it is very close to stack top, but isn't the real 1150 // stack top. Note that /proc may not exist if VM is running as a chroot 1151 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1152 // /proc/<pid>/stat could change in the future (though unlikely). 1153 // 1154 // We try __libc_stack_end first. If that doesn't work, look for 1155 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1156 // as a hint, which should work well in most cases. 1157 1158 uintptr_t stack_start; 1159 1160 // try __libc_stack_end first 1161 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1162 if (p && *p) { 1163 stack_start = *p; 1164 } else { 1165 // see if we can get the start_stack field from /proc/self/stat 1166 FILE *fp; 1167 int pid; 1168 char state; 1169 int ppid; 1170 int pgrp; 1171 int session; 1172 int nr; 1173 int tpgrp; 1174 unsigned long flags; 1175 unsigned long minflt; 1176 unsigned long cminflt; 1177 unsigned long majflt; 1178 unsigned long cmajflt; 1179 unsigned long utime; 1180 unsigned long stime; 1181 long cutime; 1182 long cstime; 1183 long prio; 1184 long nice; 1185 long junk; 1186 long it_real; 1187 uintptr_t start; 1188 uintptr_t vsize; 1189 intptr_t rss; 1190 uintptr_t rsslim; 1191 uintptr_t scodes; 1192 uintptr_t ecode; 1193 int i; 1194 1195 // Figure what the primordial thread stack base is. Code is inspired 1196 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1197 // followed by command name surrounded by parentheses, state, etc. 1198 char stat[2048]; 1199 int statlen; 1200 1201 fp = fopen("/proc/self/stat", "r"); 1202 if (fp) { 1203 statlen = fread(stat, 1, 2047, fp); 1204 stat[statlen] = '\0'; 1205 fclose(fp); 1206 1207 // Skip pid and the command string. Note that we could be dealing with 1208 // weird command names, e.g. user could decide to rename java launcher 1209 // to "java 1.4.2 :)", then the stat file would look like 1210 // 1234 (java 1.4.2 :)) R ... ... 1211 // We don't really need to know the command string, just find the last 1212 // occurrence of ")" and then start parsing from there. See bug 4726580. 1213 char * s = strrchr(stat, ')'); 1214 1215 i = 0; 1216 if (s) { 1217 // Skip blank chars 1218 do s++; while (isspace(*s)); 1219 1220 #define _UFM UINTX_FORMAT 1221 #define _DFM INTX_FORMAT 1222 1223 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1224 /* 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 */ 1225 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, 1226 &state, /* 3 %c */ 1227 &ppid, /* 4 %d */ 1228 &pgrp, /* 5 %d */ 1229 &session, /* 6 %d */ 1230 &nr, /* 7 %d */ 1231 &tpgrp, /* 8 %d */ 1232 &flags, /* 9 %lu */ 1233 &minflt, /* 10 %lu */ 1234 &cminflt, /* 11 %lu */ 1235 &majflt, /* 12 %lu */ 1236 &cmajflt, /* 13 %lu */ 1237 &utime, /* 14 %lu */ 1238 &stime, /* 15 %lu */ 1239 &cutime, /* 16 %ld */ 1240 &cstime, /* 17 %ld */ 1241 &prio, /* 18 %ld */ 1242 &nice, /* 19 %ld */ 1243 &junk, /* 20 %ld */ 1244 &it_real, /* 21 %ld */ 1245 &start, /* 22 UINTX_FORMAT */ 1246 &vsize, /* 23 UINTX_FORMAT */ 1247 &rss, /* 24 INTX_FORMAT */ 1248 &rsslim, /* 25 UINTX_FORMAT */ 1249 &scodes, /* 26 UINTX_FORMAT */ 1250 &ecode, /* 27 UINTX_FORMAT */ 1251 &stack_start); /* 28 UINTX_FORMAT */ 1252 } 1253 1254 #undef _UFM 1255 #undef _DFM 1256 1257 if (i != 28 - 2) { 1258 assert(false, "Bad conversion from /proc/self/stat"); 1259 // product mode - assume we are the initial thread, good luck in the 1260 // embedded case. 1261 warning("Can't detect initial thread stack location - bad conversion"); 1262 stack_start = (uintptr_t) &rlim; 1263 } 1264 } else { 1265 // For some reason we can't open /proc/self/stat (for example, running on 1266 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1267 // most cases, so don't abort: 1268 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1269 stack_start = (uintptr_t) &rlim; 1270 } 1271 } 1272 1273 // Now we have a pointer (stack_start) very close to the stack top, the 1274 // next thing to do is to figure out the exact location of stack top. We 1275 // can find out the virtual memory area that contains stack_start by 1276 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1277 // and its upper limit is the real stack top. (again, this would fail if 1278 // running inside chroot, because /proc may not exist.) 1279 1280 uintptr_t stack_top; 1281 address low, high; 1282 if (find_vma((address)stack_start, &low, &high)) { 1283 // success, "high" is the true stack top. (ignore "low", because initial 1284 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1285 stack_top = (uintptr_t)high; 1286 } else { 1287 // failed, likely because /proc/self/maps does not exist 1288 warning("Can't detect initial thread stack location - find_vma failed"); 1289 // best effort: stack_start is normally within a few pages below the real 1290 // stack top, use it as stack top, and reduce stack size so we won't put 1291 // guard page outside stack. 1292 stack_top = stack_start; 1293 stack_size -= 16 * page_size(); 1294 } 1295 1296 // stack_top could be partially down the page so align it 1297 stack_top = align_size_up(stack_top, page_size()); 1298 1299 if (max_size && stack_size > max_size) { 1300 _initial_thread_stack_size = max_size; 1301 } else { 1302 _initial_thread_stack_size = stack_size; 1303 } 1304 1305 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1306 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1307 } 1308 1309 //////////////////////////////////////////////////////////////////////////////// 1310 // time support 1311 1312 // Time since start-up in seconds to a fine granularity. 1313 // Used by VMSelfDestructTimer and the MemProfiler. 1314 double os::elapsedTime() { 1315 1316 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution 1317 } 1318 1319 jlong os::elapsed_counter() { 1320 return javaTimeNanos() - initial_time_count; 1321 } 1322 1323 jlong os::elapsed_frequency() { 1324 return NANOSECS_PER_SEC; // nanosecond resolution 1325 } 1326 1327 bool os::supports_vtime() { return true; } 1328 bool os::enable_vtime() { return false; } 1329 bool os::vtime_enabled() { return false; } 1330 1331 double os::elapsedVTime() { 1332 struct rusage usage; 1333 int retval = getrusage(RUSAGE_THREAD, &usage); 1334 if (retval == 0) { 1335 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); 1336 } else { 1337 // better than nothing, but not much 1338 return elapsedTime(); 1339 } 1340 } 1341 1342 jlong os::javaTimeMillis() { 1343 timeval time; 1344 int status = gettimeofday(&time, NULL); 1345 assert(status != -1, "linux error"); 1346 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1347 } 1348 1349 #ifndef CLOCK_MONOTONIC 1350 #define CLOCK_MONOTONIC (1) 1351 #endif 1352 1353 void os::Linux::clock_init() { 1354 // we do dlopen's in this particular order due to bug in linux 1355 // dynamical loader (see 6348968) leading to crash on exit 1356 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1357 if (handle == NULL) { 1358 handle = dlopen("librt.so", RTLD_LAZY); 1359 } 1360 1361 if (handle) { 1362 int (*clock_getres_func)(clockid_t, struct timespec*) = 1363 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1364 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1365 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1366 if (clock_getres_func && clock_gettime_func) { 1367 // See if monotonic clock is supported by the kernel. Note that some 1368 // early implementations simply return kernel jiffies (updated every 1369 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1370 // for nano time (though the monotonic property is still nice to have). 1371 // It's fixed in newer kernels, however clock_getres() still returns 1372 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1373 // resolution for now. Hopefully as people move to new kernels, this 1374 // won't be a problem. 1375 struct timespec res; 1376 struct timespec tp; 1377 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1378 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1379 // yes, monotonic clock is supported 1380 _clock_gettime = clock_gettime_func; 1381 return; 1382 } else { 1383 // close librt if there is no monotonic clock 1384 dlclose(handle); 1385 } 1386 } 1387 } 1388 warning("No monotonic clock was available - timed services may " \ 1389 "be adversely affected if the time-of-day clock changes"); 1390 } 1391 1392 #ifndef SYS_clock_getres 1393 1394 #if defined(IA32) || defined(AMD64) 1395 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1396 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1397 #else 1398 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1399 #define sys_clock_getres(x,y) -1 1400 #endif 1401 1402 #else 1403 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1404 #endif 1405 1406 void os::Linux::fast_thread_clock_init() { 1407 if (!UseLinuxPosixThreadCPUClocks) { 1408 return; 1409 } 1410 clockid_t clockid; 1411 struct timespec tp; 1412 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1413 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1414 1415 // Switch to using fast clocks for thread cpu time if 1416 // the sys_clock_getres() returns 0 error code. 1417 // Note, that some kernels may support the current thread 1418 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1419 // returned by the pthread_getcpuclockid(). 1420 // If the fast Posix clocks are supported then the sys_clock_getres() 1421 // must return at least tp.tv_sec == 0 which means a resolution 1422 // better than 1 sec. This is extra check for reliability. 1423 1424 if (pthread_getcpuclockid_func && 1425 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1426 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1427 1428 _supports_fast_thread_cpu_time = true; 1429 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1430 } 1431 } 1432 1433 jlong os::javaTimeNanos() { 1434 if (os::supports_monotonic_clock()) { 1435 struct timespec tp; 1436 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1437 assert(status == 0, "gettime error"); 1438 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1439 return result; 1440 } else { 1441 timeval time; 1442 int status = gettimeofday(&time, NULL); 1443 assert(status != -1, "linux error"); 1444 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1445 return 1000 * usecs; 1446 } 1447 } 1448 1449 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1450 if (os::supports_monotonic_clock()) { 1451 info_ptr->max_value = ALL_64_BITS; 1452 1453 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1454 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1455 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1456 } else { 1457 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1458 info_ptr->max_value = ALL_64_BITS; 1459 1460 // gettimeofday is a real time clock so it skips 1461 info_ptr->may_skip_backward = true; 1462 info_ptr->may_skip_forward = true; 1463 } 1464 1465 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1466 } 1467 1468 // Return the real, user, and system times in seconds from an 1469 // arbitrary fixed point in the past. 1470 bool os::getTimesSecs(double* process_real_time, 1471 double* process_user_time, 1472 double* process_system_time) { 1473 struct tms ticks; 1474 clock_t real_ticks = times(&ticks); 1475 1476 if (real_ticks == (clock_t) (-1)) { 1477 return false; 1478 } else { 1479 double ticks_per_second = (double) clock_tics_per_sec; 1480 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1481 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1482 *process_real_time = ((double) real_ticks) / ticks_per_second; 1483 1484 return true; 1485 } 1486 } 1487 1488 1489 char * os::local_time_string(char *buf, size_t buflen) { 1490 struct tm t; 1491 time_t long_time; 1492 time(&long_time); 1493 localtime_r(&long_time, &t); 1494 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1495 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1496 t.tm_hour, t.tm_min, t.tm_sec); 1497 return buf; 1498 } 1499 1500 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1501 return localtime_r(clock, res); 1502 } 1503 1504 //////////////////////////////////////////////////////////////////////////////// 1505 // runtime exit support 1506 1507 // Note: os::shutdown() might be called very early during initialization, or 1508 // called from signal handler. Before adding something to os::shutdown(), make 1509 // sure it is async-safe and can handle partially initialized VM. 1510 void os::shutdown() { 1511 1512 // allow PerfMemory to attempt cleanup of any persistent resources 1513 perfMemory_exit(); 1514 1515 // needs to remove object in file system 1516 AttachListener::abort(); 1517 1518 // flush buffered output, finish log files 1519 ostream_abort(); 1520 1521 // Check for abort hook 1522 abort_hook_t abort_hook = Arguments::abort_hook(); 1523 if (abort_hook != NULL) { 1524 abort_hook(); 1525 } 1526 1527 } 1528 1529 // Note: os::abort() might be called very early during initialization, or 1530 // called from signal handler. Before adding something to os::abort(), make 1531 // sure it is async-safe and can handle partially initialized VM. 1532 void os::abort(bool dump_core) { 1533 os::shutdown(); 1534 if (dump_core) { 1535 #ifndef PRODUCT 1536 fdStream out(defaultStream::output_fd()); 1537 out.print_raw("Current thread is "); 1538 char buf[16]; 1539 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1540 out.print_raw_cr(buf); 1541 out.print_raw_cr("Dumping core ..."); 1542 #endif 1543 ::abort(); // dump core 1544 } 1545 1546 ::exit(1); 1547 } 1548 1549 // Die immediately, no exit hook, no abort hook, no cleanup. 1550 void os::die() { 1551 // _exit() on LinuxThreads only kills current thread 1552 ::abort(); 1553 } 1554 1555 // unused on linux for now. 1556 void os::set_error_file(const char *logfile) {} 1557 1558 1559 // This method is a copy of JDK's sysGetLastErrorString 1560 // from src/solaris/hpi/src/system_md.c 1561 1562 size_t os::lasterror(char *buf, size_t len) { 1563 1564 if (errno == 0) return 0; 1565 1566 const char *s = ::strerror(errno); 1567 size_t n = ::strlen(s); 1568 if (n >= len) { 1569 n = len - 1; 1570 } 1571 ::strncpy(buf, s, n); 1572 buf[n] = '\0'; 1573 return n; 1574 } 1575 1576 intx os::current_thread_id() { return (intx)pthread_self(); } 1577 int os::current_process_id() { 1578 1579 // Under the old linux thread library, linux gives each thread 1580 // its own process id. Because of this each thread will return 1581 // a different pid if this method were to return the result 1582 // of getpid(2). Linux provides no api that returns the pid 1583 // of the launcher thread for the vm. This implementation 1584 // returns a unique pid, the pid of the launcher thread 1585 // that starts the vm 'process'. 1586 1587 // Under the NPTL, getpid() returns the same pid as the 1588 // launcher thread rather than a unique pid per thread. 1589 // Use gettid() if you want the old pre NPTL behaviour. 1590 1591 // if you are looking for the result of a call to getpid() that 1592 // returns a unique pid for the calling thread, then look at the 1593 // OSThread::thread_id() method in osThread_linux.hpp file 1594 1595 return (int)(_initial_pid ? _initial_pid : getpid()); 1596 } 1597 1598 // DLL functions 1599 1600 const char* os::dll_file_extension() { return ".so"; } 1601 1602 // This must be hard coded because it's the system's temporary 1603 // directory not the java application's temp directory, ala java.io.tmpdir. 1604 const char* os::get_temp_directory() { return "/tmp"; } 1605 1606 static bool file_exists(const char* filename) { 1607 struct stat statbuf; 1608 if (filename == NULL || strlen(filename) == 0) { 1609 return false; 1610 } 1611 return os::stat(filename, &statbuf) == 0; 1612 } 1613 1614 bool os::dll_build_name(char* buffer, size_t buflen, 1615 const char* pname, const char* fname) { 1616 bool retval = false; 1617 // Copied from libhpi 1618 const size_t pnamelen = pname ? strlen(pname) : 0; 1619 1620 // Return error on buffer overflow. 1621 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1622 return retval; 1623 } 1624 1625 if (pnamelen == 0) { 1626 snprintf(buffer, buflen, "lib%s.so", fname); 1627 retval = true; 1628 } else if (strchr(pname, *os::path_separator()) != NULL) { 1629 int n; 1630 char** pelements = split_path(pname, &n); 1631 if (pelements == NULL) { 1632 return false; 1633 } 1634 for (int i = 0; i < n; i++) { 1635 // Really shouldn't be NULL, but check can't hurt 1636 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1637 continue; // skip the empty path values 1638 } 1639 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1640 if (file_exists(buffer)) { 1641 retval = true; 1642 break; 1643 } 1644 } 1645 // release the storage 1646 for (int i = 0; i < n; i++) { 1647 if (pelements[i] != NULL) { 1648 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal); 1649 } 1650 } 1651 if (pelements != NULL) { 1652 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal); 1653 } 1654 } else { 1655 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1656 retval = true; 1657 } 1658 return retval; 1659 } 1660 1661 // check if addr is inside libjvm.so 1662 bool os::address_is_in_vm(address addr) { 1663 static address libjvm_base_addr; 1664 Dl_info dlinfo; 1665 1666 if (libjvm_base_addr == NULL) { 1667 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1668 libjvm_base_addr = (address)dlinfo.dli_fbase; 1669 } 1670 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1671 } 1672 1673 if (dladdr((void *)addr, &dlinfo) != 0) { 1674 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1675 } 1676 1677 return false; 1678 } 1679 1680 bool os::dll_address_to_function_name(address addr, char *buf, 1681 int buflen, int *offset) { 1682 // buf is not optional, but offset is optional 1683 assert(buf != NULL, "sanity check"); 1684 1685 Dl_info dlinfo; 1686 1687 if (dladdr((void*)addr, &dlinfo) != 0) { 1688 // see if we have a matching symbol 1689 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1690 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1691 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1692 } 1693 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1694 return true; 1695 } 1696 // no matching symbol so try for just file info 1697 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1698 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1699 buf, buflen, offset, dlinfo.dli_fname)) { 1700 return true; 1701 } 1702 } 1703 } 1704 1705 buf[0] = '\0'; 1706 if (offset != NULL) *offset = -1; 1707 return false; 1708 } 1709 1710 struct _address_to_library_name { 1711 address addr; // input : memory address 1712 size_t buflen; // size of fname 1713 char* fname; // output: library name 1714 address base; // library base addr 1715 }; 1716 1717 static int address_to_library_name_callback(struct dl_phdr_info *info, 1718 size_t size, void *data) { 1719 int i; 1720 bool found = false; 1721 address libbase = NULL; 1722 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1723 1724 // iterate through all loadable segments 1725 for (i = 0; i < info->dlpi_phnum; i++) { 1726 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1727 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1728 // base address of a library is the lowest address of its loaded 1729 // segments. 1730 if (libbase == NULL || libbase > segbase) { 1731 libbase = segbase; 1732 } 1733 // see if 'addr' is within current segment 1734 if (segbase <= d->addr && 1735 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1736 found = true; 1737 } 1738 } 1739 } 1740 1741 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1742 // so dll_address_to_library_name() can fall through to use dladdr() which 1743 // can figure out executable name from argv[0]. 1744 if (found && info->dlpi_name && info->dlpi_name[0]) { 1745 d->base = libbase; 1746 if (d->fname) { 1747 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1748 } 1749 return 1; 1750 } 1751 return 0; 1752 } 1753 1754 bool os::dll_address_to_library_name(address addr, char* buf, 1755 int buflen, int* offset) { 1756 // buf is not optional, but offset is optional 1757 assert(buf != NULL, "sanity check"); 1758 1759 Dl_info dlinfo; 1760 struct _address_to_library_name data; 1761 1762 // There is a bug in old glibc dladdr() implementation that it could resolve 1763 // to wrong library name if the .so file has a base address != NULL. Here 1764 // we iterate through the program headers of all loaded libraries to find 1765 // out which library 'addr' really belongs to. This workaround can be 1766 // removed once the minimum requirement for glibc is moved to 2.3.x. 1767 data.addr = addr; 1768 data.fname = buf; 1769 data.buflen = buflen; 1770 data.base = NULL; 1771 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1772 1773 if (rslt) { 1774 // buf already contains library name 1775 if (offset) *offset = addr - data.base; 1776 return true; 1777 } 1778 if (dladdr((void*)addr, &dlinfo) != 0) { 1779 if (dlinfo.dli_fname != NULL) { 1780 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1781 } 1782 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1783 *offset = addr - (address)dlinfo.dli_fbase; 1784 } 1785 return true; 1786 } 1787 1788 buf[0] = '\0'; 1789 if (offset) *offset = -1; 1790 return false; 1791 } 1792 1793 // Loads .dll/.so and 1794 // in case of error it checks if .dll/.so was built for the 1795 // same architecture as Hotspot is running on 1796 1797 1798 // Remember the stack's state. The Linux dynamic linker will change 1799 // the stack to 'executable' at most once, so we must safepoint only once. 1800 bool os::Linux::_stack_is_executable = false; 1801 1802 // VM operation that loads a library. This is necessary if stack protection 1803 // of the Java stacks can be lost during loading the library. If we 1804 // do not stop the Java threads, they can stack overflow before the stacks 1805 // are protected again. 1806 class VM_LinuxDllLoad: public VM_Operation { 1807 private: 1808 const char *_filename; 1809 char *_ebuf; 1810 int _ebuflen; 1811 void *_lib; 1812 public: 1813 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1814 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1815 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1816 void doit() { 1817 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1818 os::Linux::_stack_is_executable = true; 1819 } 1820 void* loaded_library() { return _lib; } 1821 }; 1822 1823 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1824 { 1825 void * result = NULL; 1826 bool load_attempted = false; 1827 1828 // Check whether the library to load might change execution rights 1829 // of the stack. If they are changed, the protection of the stack 1830 // guard pages will be lost. We need a safepoint to fix this. 1831 // 1832 // See Linux man page execstack(8) for more info. 1833 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1834 ElfFile ef(filename); 1835 if (!ef.specifies_noexecstack()) { 1836 if (!is_init_completed()) { 1837 os::Linux::_stack_is_executable = true; 1838 // This is OK - No Java threads have been created yet, and hence no 1839 // stack guard pages to fix. 1840 // 1841 // This should happen only when you are building JDK7 using a very 1842 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1843 // 1844 // Dynamic loader will make all stacks executable after 1845 // this function returns, and will not do that again. 1846 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1847 } else { 1848 warning("You have loaded library %s which might have disabled stack guard. " 1849 "The VM will try to fix the stack guard now.\n" 1850 "It's highly recommended that you fix the library with " 1851 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1852 filename); 1853 1854 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1855 JavaThread *jt = JavaThread::current(); 1856 if (jt->thread_state() != _thread_in_native) { 1857 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1858 // that requires ExecStack. Cannot enter safe point. Let's give up. 1859 warning("Unable to fix stack guard. Giving up."); 1860 } else { 1861 if (!LoadExecStackDllInVMThread) { 1862 // This is for the case where the DLL has an static 1863 // constructor function that executes JNI code. We cannot 1864 // load such DLLs in the VMThread. 1865 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1866 } 1867 1868 ThreadInVMfromNative tiv(jt); 1869 debug_only(VMNativeEntryWrapper vew;) 1870 1871 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1872 VMThread::execute(&op); 1873 if (LoadExecStackDllInVMThread) { 1874 result = op.loaded_library(); 1875 } 1876 load_attempted = true; 1877 } 1878 } 1879 } 1880 } 1881 1882 if (!load_attempted) { 1883 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1884 } 1885 1886 if (result != NULL) { 1887 // Successful loading 1888 return result; 1889 } 1890 1891 Elf32_Ehdr elf_head; 1892 int diag_msg_max_length=ebuflen-strlen(ebuf); 1893 char* diag_msg_buf=ebuf+strlen(ebuf); 1894 1895 if (diag_msg_max_length==0) { 1896 // No more space in ebuf for additional diagnostics message 1897 return NULL; 1898 } 1899 1900 1901 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1902 1903 if (file_descriptor < 0) { 1904 // Can't open library, report dlerror() message 1905 return NULL; 1906 } 1907 1908 bool failed_to_read_elf_head= 1909 (sizeof(elf_head)!= 1910 (::read(file_descriptor, &elf_head,sizeof(elf_head)))); 1911 1912 ::close(file_descriptor); 1913 if (failed_to_read_elf_head) { 1914 // file i/o error - report dlerror() msg 1915 return NULL; 1916 } 1917 1918 typedef struct { 1919 Elf32_Half code; // Actual value as defined in elf.h 1920 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1921 char elf_class; // 32 or 64 bit 1922 char endianess; // MSB or LSB 1923 char* name; // String representation 1924 } arch_t; 1925 1926 #ifndef EM_486 1927 #define EM_486 6 /* Intel 80486 */ 1928 #endif 1929 1930 static const arch_t arch_array[]={ 1931 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1932 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1933 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1934 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1935 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1936 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1937 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1938 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1939 #if defined(VM_LITTLE_ENDIAN) 1940 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"}, 1941 #else 1942 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1943 #endif 1944 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1945 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1946 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1947 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1948 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1949 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1950 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1951 }; 1952 1953 #if (defined IA32) 1954 static Elf32_Half running_arch_code=EM_386; 1955 #elif (defined AMD64) 1956 static Elf32_Half running_arch_code=EM_X86_64; 1957 #elif (defined IA64) 1958 static Elf32_Half running_arch_code=EM_IA_64; 1959 #elif (defined __sparc) && (defined _LP64) 1960 static Elf32_Half running_arch_code=EM_SPARCV9; 1961 #elif (defined __sparc) && (!defined _LP64) 1962 static Elf32_Half running_arch_code=EM_SPARC; 1963 #elif (defined __powerpc64__) 1964 static Elf32_Half running_arch_code=EM_PPC64; 1965 #elif (defined __powerpc__) 1966 static Elf32_Half running_arch_code=EM_PPC; 1967 #elif (defined ARM) 1968 static Elf32_Half running_arch_code=EM_ARM; 1969 #elif (defined S390) 1970 static Elf32_Half running_arch_code=EM_S390; 1971 #elif (defined ALPHA) 1972 static Elf32_Half running_arch_code=EM_ALPHA; 1973 #elif (defined MIPSEL) 1974 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1975 #elif (defined PARISC) 1976 static Elf32_Half running_arch_code=EM_PARISC; 1977 #elif (defined MIPS) 1978 static Elf32_Half running_arch_code=EM_MIPS; 1979 #elif (defined M68K) 1980 static Elf32_Half running_arch_code=EM_68K; 1981 #else 1982 #error Method os::dll_load requires that one of following is defined:\ 1983 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1984 #endif 1985 1986 // Identify compatability class for VM's architecture and library's architecture 1987 // Obtain string descriptions for architectures 1988 1989 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1990 int running_arch_index=-1; 1991 1992 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) { 1993 if (running_arch_code == arch_array[i].code) { 1994 running_arch_index = i; 1995 } 1996 if (lib_arch.code == arch_array[i].code) { 1997 lib_arch.compat_class = arch_array[i].compat_class; 1998 lib_arch.name = arch_array[i].name; 1999 } 2000 } 2001 2002 assert(running_arch_index != -1, 2003 "Didn't find running architecture code (running_arch_code) in arch_array"); 2004 if (running_arch_index == -1) { 2005 // Even though running architecture detection failed 2006 // we may still continue with reporting dlerror() message 2007 return NULL; 2008 } 2009 2010 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 2011 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 2012 return NULL; 2013 } 2014 2015 #ifndef S390 2016 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 2017 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 2018 return NULL; 2019 } 2020 #endif // !S390 2021 2022 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 2023 if (lib_arch.name!=NULL) { 2024 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2025 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 2026 lib_arch.name, arch_array[running_arch_index].name); 2027 } else { 2028 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2029 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 2030 lib_arch.code, 2031 arch_array[running_arch_index].name); 2032 } 2033 } 2034 2035 return NULL; 2036 } 2037 2038 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) { 2039 void * result = ::dlopen(filename, RTLD_LAZY); 2040 if (result == NULL) { 2041 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2042 ebuf[ebuflen-1] = '\0'; 2043 } 2044 return result; 2045 } 2046 2047 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) { 2048 void * result = NULL; 2049 if (LoadExecStackDllInVMThread) { 2050 result = dlopen_helper(filename, ebuf, ebuflen); 2051 } 2052 2053 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2054 // library that requires an executable stack, or which does not have this 2055 // stack attribute set, dlopen changes the stack attribute to executable. The 2056 // read protection of the guard pages gets lost. 2057 // 2058 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2059 // may have been queued at the same time. 2060 2061 if (!_stack_is_executable) { 2062 JavaThread *jt = Threads::first(); 2063 2064 while (jt) { 2065 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2066 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2067 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2068 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2069 warning("Attempt to reguard stack yellow zone failed."); 2070 } 2071 } 2072 jt = jt->next(); 2073 } 2074 } 2075 2076 return result; 2077 } 2078 2079 /* 2080 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2081 * chances are you might want to run the generated bits against glibc-2.0 2082 * libdl.so, so always use locking for any version of glibc. 2083 */ 2084 void* os::dll_lookup(void* handle, const char* name) { 2085 pthread_mutex_lock(&dl_mutex); 2086 void* res = dlsym(handle, name); 2087 pthread_mutex_unlock(&dl_mutex); 2088 return res; 2089 } 2090 2091 void* os::get_default_process_handle() { 2092 return (void*)::dlopen(NULL, RTLD_LAZY); 2093 } 2094 2095 static bool _print_ascii_file(const char* filename, outputStream* st) { 2096 int fd = ::open(filename, O_RDONLY); 2097 if (fd == -1) { 2098 return false; 2099 } 2100 2101 char buf[32]; 2102 int bytes; 2103 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2104 st->print_raw(buf, bytes); 2105 } 2106 2107 ::close(fd); 2108 2109 return true; 2110 } 2111 2112 void os::print_dll_info(outputStream *st) { 2113 st->print_cr("Dynamic libraries:"); 2114 2115 char fname[32]; 2116 pid_t pid = os::Linux::gettid(); 2117 2118 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2119 2120 if (!_print_ascii_file(fname, st)) { 2121 st->print("Can not get library information for pid = %d\n", pid); 2122 } 2123 } 2124 2125 void os::print_os_info_brief(outputStream* st) { 2126 os::Linux::print_distro_info(st); 2127 2128 os::Posix::print_uname_info(st); 2129 2130 os::Linux::print_libversion_info(st); 2131 2132 } 2133 2134 void os::print_os_info(outputStream* st) { 2135 st->print("OS:"); 2136 2137 os::Linux::print_distro_info(st); 2138 2139 os::Posix::print_uname_info(st); 2140 2141 // Print warning if unsafe chroot environment detected 2142 if (unsafe_chroot_detected) { 2143 st->print("WARNING!! "); 2144 st->print_cr("%s", unstable_chroot_error); 2145 } 2146 2147 os::Linux::print_libversion_info(st); 2148 2149 os::Posix::print_rlimit_info(st); 2150 2151 os::Posix::print_load_average(st); 2152 2153 os::Linux::print_full_memory_info(st); 2154 } 2155 2156 // Try to identify popular distros. 2157 // Most Linux distributions have a /etc/XXX-release file, which contains 2158 // the OS version string. Newer Linux distributions have a /etc/lsb-release 2159 // file that also contains the OS version string. Some have more than one 2160 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2161 // /etc/redhat-release.), so the order is important. 2162 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2163 // their own specific XXX-release file as well as a redhat-release file. 2164 // Because of this the XXX-release file needs to be searched for before the 2165 // redhat-release file. 2166 // Since Red Hat has a lsb-release file that is not very descriptive the 2167 // search for redhat-release needs to be before lsb-release. 2168 // Since the lsb-release file is the new standard it needs to be searched 2169 // before the older style release files. 2170 // Searching system-release (Red Hat) and os-release (other Linuxes) are a 2171 // next to last resort. The os-release file is a new standard that contains 2172 // distribution information and the system-release file seems to be an old 2173 // standard that has been replaced by the lsb-release and os-release files. 2174 // Searching for the debian_version file is the last resort. It contains 2175 // an informative string like "6.0.6" or "wheezy/sid". Because of this 2176 // "Debian " is printed before the contents of the debian_version file. 2177 void os::Linux::print_distro_info(outputStream* st) { 2178 if (!_print_ascii_file("/etc/oracle-release", st) && 2179 !_print_ascii_file("/etc/mandriva-release", st) && 2180 !_print_ascii_file("/etc/mandrake-release", st) && 2181 !_print_ascii_file("/etc/sun-release", st) && 2182 !_print_ascii_file("/etc/redhat-release", st) && 2183 !_print_ascii_file("/etc/lsb-release", st) && 2184 !_print_ascii_file("/etc/SuSE-release", st) && 2185 !_print_ascii_file("/etc/turbolinux-release", st) && 2186 !_print_ascii_file("/etc/gentoo-release", st) && 2187 !_print_ascii_file("/etc/ltib-release", st) && 2188 !_print_ascii_file("/etc/angstrom-version", st) && 2189 !_print_ascii_file("/etc/system-release", st) && 2190 !_print_ascii_file("/etc/os-release", st)) { 2191 2192 if (file_exists("/etc/debian_version")) { 2193 st->print("Debian "); 2194 _print_ascii_file("/etc/debian_version", st); 2195 } else { 2196 st->print("Linux"); 2197 } 2198 } 2199 st->cr(); 2200 } 2201 2202 void os::Linux::print_libversion_info(outputStream* st) { 2203 // libc, pthread 2204 st->print("libc:"); 2205 st->print("%s ", os::Linux::glibc_version()); 2206 st->print("%s ", os::Linux::libpthread_version()); 2207 if (os::Linux::is_LinuxThreads()) { 2208 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2209 } 2210 st->cr(); 2211 } 2212 2213 void os::Linux::print_full_memory_info(outputStream* st) { 2214 st->print("\n/proc/meminfo:\n"); 2215 _print_ascii_file("/proc/meminfo", st); 2216 st->cr(); 2217 } 2218 2219 void os::print_memory_info(outputStream* st) { 2220 2221 st->print("Memory:"); 2222 st->print(" %dk page", os::vm_page_size()>>10); 2223 2224 // values in struct sysinfo are "unsigned long" 2225 struct sysinfo si; 2226 sysinfo(&si); 2227 2228 st->print(", physical " UINT64_FORMAT "k", 2229 os::physical_memory() >> 10); 2230 st->print("(" UINT64_FORMAT "k free)", 2231 os::available_memory() >> 10); 2232 st->print(", swap " UINT64_FORMAT "k", 2233 ((jlong)si.totalswap * si.mem_unit) >> 10); 2234 st->print("(" UINT64_FORMAT "k free)", 2235 ((jlong)si.freeswap * si.mem_unit) >> 10); 2236 st->cr(); 2237 } 2238 2239 void os::pd_print_cpu_info(outputStream* st) { 2240 st->print("\n/proc/cpuinfo:\n"); 2241 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2242 st->print(" <Not Available>"); 2243 } 2244 st->cr(); 2245 } 2246 2247 void os::print_siginfo(outputStream* st, void* siginfo) { 2248 const siginfo_t* si = (const siginfo_t*)siginfo; 2249 2250 os::Posix::print_siginfo_brief(st, si); 2251 2252 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2253 UseSharedSpaces) { 2254 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2255 if (mapinfo->is_in_shared_space(si->si_addr)) { 2256 st->print("\n\nError accessing class data sharing archive." \ 2257 " Mapped file inaccessible during execution, " \ 2258 " possible disk/network problem."); 2259 } 2260 } 2261 st->cr(); 2262 } 2263 2264 2265 static void print_signal_handler(outputStream* st, int sig, 2266 char* buf, size_t buflen); 2267 2268 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2269 st->print_cr("Signal Handlers:"); 2270 print_signal_handler(st, SIGSEGV, buf, buflen); 2271 print_signal_handler(st, SIGBUS , buf, buflen); 2272 print_signal_handler(st, SIGFPE , buf, buflen); 2273 print_signal_handler(st, SIGPIPE, buf, buflen); 2274 print_signal_handler(st, SIGXFSZ, buf, buflen); 2275 print_signal_handler(st, SIGILL , buf, buflen); 2276 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2277 print_signal_handler(st, SR_signum, buf, buflen); 2278 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2279 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2280 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2281 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2282 #if defined(PPC64) 2283 print_signal_handler(st, SIGTRAP, buf, buflen); 2284 #endif 2285 } 2286 2287 static char saved_jvm_path[MAXPATHLEN] = {0}; 2288 2289 // Find the full path to the current module, libjvm.so 2290 void os::jvm_path(char *buf, jint buflen) { 2291 // Error checking. 2292 if (buflen < MAXPATHLEN) { 2293 assert(false, "must use a large-enough buffer"); 2294 buf[0] = '\0'; 2295 return; 2296 } 2297 // Lazy resolve the path to current module. 2298 if (saved_jvm_path[0] != 0) { 2299 strcpy(buf, saved_jvm_path); 2300 return; 2301 } 2302 2303 char dli_fname[MAXPATHLEN]; 2304 bool ret = dll_address_to_library_name( 2305 CAST_FROM_FN_PTR(address, os::jvm_path), 2306 dli_fname, sizeof(dli_fname), NULL); 2307 assert(ret, "cannot locate libjvm"); 2308 char *rp = NULL; 2309 if (ret && dli_fname[0] != '\0') { 2310 rp = realpath(dli_fname, buf); 2311 } 2312 if (rp == NULL) 2313 return; 2314 2315 if (Arguments::sun_java_launcher_is_altjvm()) { 2316 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical 2317 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". 2318 // If "/jre/lib/" appears at the right place in the string, then 2319 // assume we are installed in a JDK and we're done. Otherwise, check 2320 // for a JAVA_HOME environment variable and fix up the path so it 2321 // looks like libjvm.so is installed there (append a fake suffix 2322 // hotspot/libjvm.so). 2323 const char *p = buf + strlen(buf) - 1; 2324 for (int count = 0; p > buf && count < 5; ++count) { 2325 for (--p; p > buf && *p != '/'; --p) 2326 /* empty */ ; 2327 } 2328 2329 if (strncmp(p, "/jre/lib/", 9) != 0) { 2330 // Look for JAVA_HOME in the environment. 2331 char* java_home_var = ::getenv("JAVA_HOME"); 2332 if (java_home_var != NULL && java_home_var[0] != 0) { 2333 char* jrelib_p; 2334 int len; 2335 2336 // Check the current module name "libjvm.so". 2337 p = strrchr(buf, '/'); 2338 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2339 2340 rp = realpath(java_home_var, buf); 2341 if (rp == NULL) 2342 return; 2343 2344 // determine if this is a legacy image or modules image 2345 // modules image doesn't have "jre" subdirectory 2346 len = strlen(buf); 2347 jrelib_p = buf + len; 2348 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2349 if (0 != access(buf, F_OK)) { 2350 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2351 } 2352 2353 if (0 == access(buf, F_OK)) { 2354 // Use current module name "libjvm.so" 2355 len = strlen(buf); 2356 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2357 } else { 2358 // Go back to path of .so 2359 rp = realpath(dli_fname, buf); 2360 if (rp == NULL) 2361 return; 2362 } 2363 } 2364 } 2365 } 2366 2367 strcpy(saved_jvm_path, buf); 2368 } 2369 2370 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2371 // no prefix required, not even "_" 2372 } 2373 2374 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2375 // no suffix required 2376 } 2377 2378 //////////////////////////////////////////////////////////////////////////////// 2379 // sun.misc.Signal support 2380 2381 static volatile jint sigint_count = 0; 2382 2383 static void 2384 UserHandler(int sig, void *siginfo, void *context) { 2385 // 4511530 - sem_post is serialized and handled by the manager thread. When 2386 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2387 // don't want to flood the manager thread with sem_post requests. 2388 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2389 return; 2390 2391 // Ctrl-C is pressed during error reporting, likely because the error 2392 // handler fails to abort. Let VM die immediately. 2393 if (sig == SIGINT && is_error_reported()) { 2394 os::die(); 2395 } 2396 2397 os::signal_notify(sig); 2398 } 2399 2400 void* os::user_handler() { 2401 return CAST_FROM_FN_PTR(void*, UserHandler); 2402 } 2403 2404 class Semaphore : public StackObj { 2405 public: 2406 Semaphore(); 2407 ~Semaphore(); 2408 void signal(); 2409 void wait(); 2410 bool trywait(); 2411 bool timedwait(unsigned int sec, int nsec); 2412 private: 2413 sem_t _semaphore; 2414 }; 2415 2416 Semaphore::Semaphore() { 2417 sem_init(&_semaphore, 0, 0); 2418 } 2419 2420 Semaphore::~Semaphore() { 2421 sem_destroy(&_semaphore); 2422 } 2423 2424 void Semaphore::signal() { 2425 sem_post(&_semaphore); 2426 } 2427 2428 void Semaphore::wait() { 2429 sem_wait(&_semaphore); 2430 } 2431 2432 bool Semaphore::trywait() { 2433 return sem_trywait(&_semaphore) == 0; 2434 } 2435 2436 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2437 2438 struct timespec ts; 2439 // Semaphore's are always associated with CLOCK_REALTIME 2440 os::Linux::clock_gettime(CLOCK_REALTIME, &ts); 2441 // see unpackTime for discussion on overflow checking 2442 if (sec >= MAX_SECS) { 2443 ts.tv_sec += MAX_SECS; 2444 ts.tv_nsec = 0; 2445 } else { 2446 ts.tv_sec += sec; 2447 ts.tv_nsec += nsec; 2448 if (ts.tv_nsec >= NANOSECS_PER_SEC) { 2449 ts.tv_nsec -= NANOSECS_PER_SEC; 2450 ++ts.tv_sec; // note: this must be <= max_secs 2451 } 2452 } 2453 2454 while (1) { 2455 int result = sem_timedwait(&_semaphore, &ts); 2456 if (result == 0) { 2457 return true; 2458 } else if (errno == EINTR) { 2459 continue; 2460 } else if (errno == ETIMEDOUT) { 2461 return false; 2462 } else { 2463 return false; 2464 } 2465 } 2466 } 2467 2468 extern "C" { 2469 typedef void (*sa_handler_t)(int); 2470 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2471 } 2472 2473 void* os::signal(int signal_number, void* handler) { 2474 struct sigaction sigAct, oldSigAct; 2475 2476 sigfillset(&(sigAct.sa_mask)); 2477 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2478 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2479 2480 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2481 // -1 means registration failed 2482 return (void *)-1; 2483 } 2484 2485 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2486 } 2487 2488 void os::signal_raise(int signal_number) { 2489 ::raise(signal_number); 2490 } 2491 2492 /* 2493 * The following code is moved from os.cpp for making this 2494 * code platform specific, which it is by its very nature. 2495 */ 2496 2497 // Will be modified when max signal is changed to be dynamic 2498 int os::sigexitnum_pd() { 2499 return NSIG; 2500 } 2501 2502 // a counter for each possible signal value 2503 static volatile jint pending_signals[NSIG+1] = { 0 }; 2504 2505 // Linux(POSIX) specific hand shaking semaphore. 2506 static sem_t sig_sem; 2507 static Semaphore sr_semaphore; 2508 2509 void os::signal_init_pd() { 2510 // Initialize signal structures 2511 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2512 2513 // Initialize signal semaphore 2514 ::sem_init(&sig_sem, 0, 0); 2515 } 2516 2517 void os::signal_notify(int sig) { 2518 Atomic::inc(&pending_signals[sig]); 2519 ::sem_post(&sig_sem); 2520 } 2521 2522 static int check_pending_signals(bool wait) { 2523 Atomic::store(0, &sigint_count); 2524 for (;;) { 2525 for (int i = 0; i < NSIG + 1; i++) { 2526 jint n = pending_signals[i]; 2527 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2528 return i; 2529 } 2530 } 2531 if (!wait) { 2532 return -1; 2533 } 2534 JavaThread *thread = JavaThread::current(); 2535 ThreadBlockInVM tbivm(thread); 2536 2537 bool threadIsSuspended; 2538 do { 2539 thread->set_suspend_equivalent(); 2540 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2541 ::sem_wait(&sig_sem); 2542 2543 // were we externally suspended while we were waiting? 2544 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2545 if (threadIsSuspended) { 2546 // 2547 // The semaphore has been incremented, but while we were waiting 2548 // another thread suspended us. We don't want to continue running 2549 // while suspended because that would surprise the thread that 2550 // suspended us. 2551 // 2552 ::sem_post(&sig_sem); 2553 2554 thread->java_suspend_self(); 2555 } 2556 } while (threadIsSuspended); 2557 } 2558 } 2559 2560 int os::signal_lookup() { 2561 return check_pending_signals(false); 2562 } 2563 2564 int os::signal_wait() { 2565 return check_pending_signals(true); 2566 } 2567 2568 //////////////////////////////////////////////////////////////////////////////// 2569 // Virtual Memory 2570 2571 int os::vm_page_size() { 2572 // Seems redundant as all get out 2573 assert(os::Linux::page_size() != -1, "must call os::init"); 2574 return os::Linux::page_size(); 2575 } 2576 2577 // Solaris allocates memory by pages. 2578 int os::vm_allocation_granularity() { 2579 assert(os::Linux::page_size() != -1, "must call os::init"); 2580 return os::Linux::page_size(); 2581 } 2582 2583 // Rationale behind this function: 2584 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2585 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2586 // samples for JITted code. Here we create private executable mapping over the code cache 2587 // and then we can use standard (well, almost, as mapping can change) way to provide 2588 // info for the reporting script by storing timestamp and location of symbol 2589 void linux_wrap_code(char* base, size_t size) { 2590 static volatile jint cnt = 0; 2591 2592 if (!UseOprofile) { 2593 return; 2594 } 2595 2596 char buf[PATH_MAX+1]; 2597 int num = Atomic::add(1, &cnt); 2598 2599 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2600 os::get_temp_directory(), os::current_process_id(), num); 2601 unlink(buf); 2602 2603 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2604 2605 if (fd != -1) { 2606 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2607 if (rv != (off_t)-1) { 2608 if (::write(fd, "", 1) == 1) { 2609 mmap(base, size, 2610 PROT_READ|PROT_WRITE|PROT_EXEC, 2611 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2612 } 2613 } 2614 ::close(fd); 2615 unlink(buf); 2616 } 2617 } 2618 2619 static bool recoverable_mmap_error(int err) { 2620 // See if the error is one we can let the caller handle. This 2621 // list of errno values comes from JBS-6843484. I can't find a 2622 // Linux man page that documents this specific set of errno 2623 // values so while this list currently matches Solaris, it may 2624 // change as we gain experience with this failure mode. 2625 switch (err) { 2626 case EBADF: 2627 case EINVAL: 2628 case ENOTSUP: 2629 // let the caller deal with these errors 2630 return true; 2631 2632 default: 2633 // Any remaining errors on this OS can cause our reserved mapping 2634 // to be lost. That can cause confusion where different data 2635 // structures think they have the same memory mapped. The worst 2636 // scenario is if both the VM and a library think they have the 2637 // same memory mapped. 2638 return false; 2639 } 2640 } 2641 2642 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2643 int err) { 2644 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2645 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2646 strerror(err), err); 2647 } 2648 2649 static void warn_fail_commit_memory(char* addr, size_t size, 2650 size_t alignment_hint, bool exec, 2651 int err) { 2652 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2653 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2654 alignment_hint, exec, strerror(err), err); 2655 } 2656 2657 // NOTE: Linux kernel does not really reserve the pages for us. 2658 // All it does is to check if there are enough free pages 2659 // left at the time of mmap(). This could be a potential 2660 // problem. 2661 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2662 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2663 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2664 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2665 if (res != (uintptr_t) MAP_FAILED) { 2666 if (UseNUMAInterleaving) { 2667 numa_make_global(addr, size); 2668 } 2669 return 0; 2670 } 2671 2672 int err = errno; // save errno from mmap() call above 2673 2674 if (!recoverable_mmap_error(err)) { 2675 warn_fail_commit_memory(addr, size, exec, err); 2676 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2677 } 2678 2679 return err; 2680 } 2681 2682 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2683 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2684 } 2685 2686 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2687 const char* mesg) { 2688 assert(mesg != NULL, "mesg must be specified"); 2689 int err = os::Linux::commit_memory_impl(addr, size, exec); 2690 if (err != 0) { 2691 // the caller wants all commit errors to exit with the specified mesg: 2692 warn_fail_commit_memory(addr, size, exec, err); 2693 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2694 } 2695 } 2696 2697 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2698 #ifndef MAP_HUGETLB 2699 #define MAP_HUGETLB 0x40000 2700 #endif 2701 2702 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2703 #ifndef MADV_HUGEPAGE 2704 #define MADV_HUGEPAGE 14 2705 #endif 2706 2707 int os::Linux::commit_memory_impl(char* addr, size_t size, 2708 size_t alignment_hint, bool exec) { 2709 int err = os::Linux::commit_memory_impl(addr, size, exec); 2710 if (err == 0) { 2711 realign_memory(addr, size, alignment_hint); 2712 } 2713 return err; 2714 } 2715 2716 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2717 bool exec) { 2718 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2719 } 2720 2721 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2722 size_t alignment_hint, bool exec, 2723 const char* mesg) { 2724 assert(mesg != NULL, "mesg must be specified"); 2725 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2726 if (err != 0) { 2727 // the caller wants all commit errors to exit with the specified mesg: 2728 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2729 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2730 } 2731 } 2732 2733 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2734 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2735 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2736 // be supported or the memory may already be backed by huge pages. 2737 ::madvise(addr, bytes, MADV_HUGEPAGE); 2738 } 2739 } 2740 2741 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2742 // This method works by doing an mmap over an existing mmaping and effectively discarding 2743 // the existing pages. However it won't work for SHM-based large pages that cannot be 2744 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2745 // small pages on top of the SHM segment. This method always works for small pages, so we 2746 // allow that in any case. 2747 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2748 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2749 } 2750 } 2751 2752 void os::numa_make_global(char *addr, size_t bytes) { 2753 Linux::numa_interleave_memory(addr, bytes); 2754 } 2755 2756 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2757 // bind policy to MPOL_PREFERRED for the current thread. 2758 #define USE_MPOL_PREFERRED 0 2759 2760 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2761 // To make NUMA and large pages more robust when both enabled, we need to ease 2762 // the requirements on where the memory should be allocated. MPOL_BIND is the 2763 // default policy and it will force memory to be allocated on the specified 2764 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2765 // the specified node, but will not force it. Using this policy will prevent 2766 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2767 // free large pages. 2768 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2769 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2770 } 2771 2772 bool os::numa_topology_changed() { return false; } 2773 2774 size_t os::numa_get_groups_num() { 2775 int max_node = Linux::numa_max_node(); 2776 return max_node > 0 ? max_node + 1 : 1; 2777 } 2778 2779 int os::numa_get_group_id() { 2780 int cpu_id = Linux::sched_getcpu(); 2781 if (cpu_id != -1) { 2782 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2783 if (lgrp_id != -1) { 2784 return lgrp_id; 2785 } 2786 } 2787 return 0; 2788 } 2789 2790 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2791 for (size_t i = 0; i < size; i++) { 2792 ids[i] = i; 2793 } 2794 return size; 2795 } 2796 2797 bool os::get_page_info(char *start, page_info* info) { 2798 return false; 2799 } 2800 2801 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2802 return end; 2803 } 2804 2805 2806 int os::Linux::sched_getcpu_syscall(void) { 2807 unsigned int cpu; 2808 int retval = -1; 2809 2810 #if defined(IA32) 2811 # ifndef SYS_getcpu 2812 # define SYS_getcpu 318 2813 # endif 2814 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2815 #elif defined(AMD64) 2816 // Unfortunately we have to bring all these macros here from vsyscall.h 2817 // to be able to compile on old linuxes. 2818 # define __NR_vgetcpu 2 2819 # define VSYSCALL_START (-10UL << 20) 2820 # define VSYSCALL_SIZE 1024 2821 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2822 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2823 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2824 retval = vgetcpu(&cpu, NULL, NULL); 2825 #endif 2826 2827 return (retval == -1) ? retval : cpu; 2828 } 2829 2830 // Something to do with the numa-aware allocator needs these symbols 2831 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2832 extern "C" JNIEXPORT void numa_error(char *where) { } 2833 extern "C" JNIEXPORT int fork1() { return fork(); } 2834 2835 2836 // If we are running with libnuma version > 2, then we should 2837 // be trying to use symbols with versions 1.1 2838 // If we are running with earlier version, which did not have symbol versions, 2839 // we should use the base version. 2840 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2841 void *f = dlvsym(handle, name, "libnuma_1.1"); 2842 if (f == NULL) { 2843 f = dlsym(handle, name); 2844 } 2845 return f; 2846 } 2847 2848 bool os::Linux::libnuma_init() { 2849 // sched_getcpu() should be in libc. 2850 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2851 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2852 2853 // If it's not, try a direct syscall. 2854 if (sched_getcpu() == -1) 2855 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall)); 2856 2857 if (sched_getcpu() != -1) { // Does it work? 2858 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2859 if (handle != NULL) { 2860 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2861 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2862 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2863 libnuma_dlsym(handle, "numa_max_node"))); 2864 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2865 libnuma_dlsym(handle, "numa_available"))); 2866 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2867 libnuma_dlsym(handle, "numa_tonode_memory"))); 2868 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2869 libnuma_dlsym(handle, "numa_interleave_memory"))); 2870 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2871 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2872 2873 2874 if (numa_available() != -1) { 2875 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2876 // Create a cpu -> node mapping 2877 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2878 rebuild_cpu_to_node_map(); 2879 return true; 2880 } 2881 } 2882 } 2883 return false; 2884 } 2885 2886 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2887 // The table is later used in get_node_by_cpu(). 2888 void os::Linux::rebuild_cpu_to_node_map() { 2889 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2890 // in libnuma (possible values are starting from 16, 2891 // and continuing up with every other power of 2, but less 2892 // than the maximum number of CPUs supported by kernel), and 2893 // is a subject to change (in libnuma version 2 the requirements 2894 // are more reasonable) we'll just hardcode the number they use 2895 // in the library. 2896 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2897 2898 size_t cpu_num = os::active_processor_count(); 2899 size_t cpu_map_size = NCPUS / BitsPerCLong; 2900 size_t cpu_map_valid_size = 2901 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2902 2903 cpu_to_node()->clear(); 2904 cpu_to_node()->at_grow(cpu_num - 1); 2905 size_t node_num = numa_get_groups_num(); 2906 2907 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2908 for (size_t i = 0; i < node_num; i++) { 2909 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2910 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2911 if (cpu_map[j] != 0) { 2912 for (size_t k = 0; k < BitsPerCLong; k++) { 2913 if (cpu_map[j] & (1UL << k)) { 2914 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2915 } 2916 } 2917 } 2918 } 2919 } 2920 } 2921 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal); 2922 } 2923 2924 int os::Linux::get_node_by_cpu(int cpu_id) { 2925 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2926 return cpu_to_node()->at(cpu_id); 2927 } 2928 return -1; 2929 } 2930 2931 GrowableArray<int>* os::Linux::_cpu_to_node; 2932 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2933 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2934 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2935 os::Linux::numa_available_func_t os::Linux::_numa_available; 2936 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2937 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2938 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2939 unsigned long* os::Linux::_numa_all_nodes; 2940 2941 bool os::pd_uncommit_memory(char* addr, size_t size) { 2942 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2943 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2944 return res != (uintptr_t) MAP_FAILED; 2945 } 2946 2947 static 2948 address get_stack_commited_bottom(address bottom, size_t size) { 2949 address nbot = bottom; 2950 address ntop = bottom + size; 2951 2952 size_t page_sz = os::vm_page_size(); 2953 unsigned pages = size / page_sz; 2954 2955 unsigned char vec[1]; 2956 unsigned imin = 1, imax = pages + 1, imid; 2957 int mincore_return_value = 0; 2958 2959 assert(imin <= imax, "Unexpected page size"); 2960 2961 while (imin < imax) { 2962 imid = (imax + imin) / 2; 2963 nbot = ntop - (imid * page_sz); 2964 2965 // Use a trick with mincore to check whether the page is mapped or not. 2966 // mincore sets vec to 1 if page resides in memory and to 0 if page 2967 // is swapped output but if page we are asking for is unmapped 2968 // it returns -1,ENOMEM 2969 mincore_return_value = mincore(nbot, page_sz, vec); 2970 2971 if (mincore_return_value == -1) { 2972 // Page is not mapped go up 2973 // to find first mapped page 2974 if (errno != EAGAIN) { 2975 assert(errno == ENOMEM, "Unexpected mincore errno"); 2976 imax = imid; 2977 } 2978 } else { 2979 // Page is mapped go down 2980 // to find first not mapped page 2981 imin = imid + 1; 2982 } 2983 } 2984 2985 nbot = nbot + page_sz; 2986 2987 // Adjust stack bottom one page up if last checked page is not mapped 2988 if (mincore_return_value == -1) { 2989 nbot = nbot + page_sz; 2990 } 2991 2992 return nbot; 2993 } 2994 2995 2996 // Linux uses a growable mapping for the stack, and if the mapping for 2997 // the stack guard pages is not removed when we detach a thread the 2998 // stack cannot grow beyond the pages where the stack guard was 2999 // mapped. If at some point later in the process the stack expands to 3000 // that point, the Linux kernel cannot expand the stack any further 3001 // because the guard pages are in the way, and a segfault occurs. 3002 // 3003 // However, it's essential not to split the stack region by unmapping 3004 // a region (leaving a hole) that's already part of the stack mapping, 3005 // so if the stack mapping has already grown beyond the guard pages at 3006 // the time we create them, we have to truncate the stack mapping. 3007 // So, we need to know the extent of the stack mapping when 3008 // create_stack_guard_pages() is called. 3009 3010 // We only need this for stacks that are growable: at the time of 3011 // writing thread stacks don't use growable mappings (i.e. those 3012 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 3013 // only applies to the main thread. 3014 3015 // If the (growable) stack mapping already extends beyond the point 3016 // where we're going to put our guard pages, truncate the mapping at 3017 // that point by munmap()ping it. This ensures that when we later 3018 // munmap() the guard pages we don't leave a hole in the stack 3019 // mapping. This only affects the main/initial thread 3020 3021 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3022 3023 if (os::Linux::is_initial_thread()) { 3024 // As we manually grow stack up to bottom inside create_attached_thread(), 3025 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3026 // we don't need to do anything special. 3027 // Check it first, before calling heavy function. 3028 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3029 unsigned char vec[1]; 3030 3031 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3032 // Fallback to slow path on all errors, including EAGAIN 3033 stack_extent = (uintptr_t) get_stack_commited_bottom( 3034 os::Linux::initial_thread_stack_bottom(), 3035 (size_t)addr - stack_extent); 3036 } 3037 3038 if (stack_extent < (uintptr_t)addr) { 3039 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3040 } 3041 } 3042 3043 return os::commit_memory(addr, size, !ExecMem); 3044 } 3045 3046 // If this is a growable mapping, remove the guard pages entirely by 3047 // munmap()ping them. If not, just call uncommit_memory(). This only 3048 // affects the main/initial thread, but guard against future OS changes 3049 // It's safe to always unmap guard pages for initial thread because we 3050 // always place it right after end of the mapped region 3051 3052 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3053 uintptr_t stack_extent, stack_base; 3054 3055 if (os::Linux::is_initial_thread()) { 3056 return ::munmap(addr, size) == 0; 3057 } 3058 3059 return os::uncommit_memory(addr, size); 3060 } 3061 3062 static address _highest_vm_reserved_address = NULL; 3063 3064 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3065 // at 'requested_addr'. If there are existing memory mappings at the same 3066 // location, however, they will be overwritten. If 'fixed' is false, 3067 // 'requested_addr' is only treated as a hint, the return value may or 3068 // may not start from the requested address. Unlike Linux mmap(), this 3069 // function returns NULL to indicate failure. 3070 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3071 char * addr; 3072 int flags; 3073 3074 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3075 if (fixed) { 3076 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3077 flags |= MAP_FIXED; 3078 } 3079 3080 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3081 // touch an uncommitted page. Otherwise, the read/write might 3082 // succeed if we have enough swap space to back the physical page. 3083 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3084 flags, -1, 0); 3085 3086 if (addr != MAP_FAILED) { 3087 // anon_mmap() should only get called during VM initialization, 3088 // don't need lock (actually we can skip locking even it can be called 3089 // from multiple threads, because _highest_vm_reserved_address is just a 3090 // hint about the upper limit of non-stack memory regions.) 3091 if ((address)addr + bytes > _highest_vm_reserved_address) { 3092 _highest_vm_reserved_address = (address)addr + bytes; 3093 } 3094 } 3095 3096 return addr == MAP_FAILED ? NULL : addr; 3097 } 3098 3099 // Don't update _highest_vm_reserved_address, because there might be memory 3100 // regions above addr + size. If so, releasing a memory region only creates 3101 // a hole in the address space, it doesn't help prevent heap-stack collision. 3102 // 3103 static int anon_munmap(char * addr, size_t size) { 3104 return ::munmap(addr, size) == 0; 3105 } 3106 3107 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3108 size_t alignment_hint) { 3109 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3110 } 3111 3112 bool os::pd_release_memory(char* addr, size_t size) { 3113 return anon_munmap(addr, size); 3114 } 3115 3116 static address highest_vm_reserved_address() { 3117 return _highest_vm_reserved_address; 3118 } 3119 3120 static bool linux_mprotect(char* addr, size_t size, int prot) { 3121 // Linux wants the mprotect address argument to be page aligned. 3122 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3123 3124 // According to SUSv3, mprotect() should only be used with mappings 3125 // established by mmap(), and mmap() always maps whole pages. Unaligned 3126 // 'addr' likely indicates problem in the VM (e.g. trying to change 3127 // protection of malloc'ed or statically allocated memory). Check the 3128 // caller if you hit this assert. 3129 assert(addr == bottom, "sanity check"); 3130 3131 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3132 return ::mprotect(bottom, size, prot) == 0; 3133 } 3134 3135 // Set protections specified 3136 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3137 bool is_committed) { 3138 unsigned int p = 0; 3139 switch (prot) { 3140 case MEM_PROT_NONE: p = PROT_NONE; break; 3141 case MEM_PROT_READ: p = PROT_READ; break; 3142 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3143 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3144 default: 3145 ShouldNotReachHere(); 3146 } 3147 // is_committed is unused. 3148 return linux_mprotect(addr, bytes, p); 3149 } 3150 3151 bool os::guard_memory(char* addr, size_t size) { 3152 return linux_mprotect(addr, size, PROT_NONE); 3153 } 3154 3155 bool os::unguard_memory(char* addr, size_t size) { 3156 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3157 } 3158 3159 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) { 3160 bool result = false; 3161 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3162 MAP_ANONYMOUS|MAP_PRIVATE, 3163 -1, 0); 3164 if (p != MAP_FAILED) { 3165 void *aligned_p = align_ptr_up(p, page_size); 3166 3167 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3168 3169 munmap(p, page_size * 2); 3170 } 3171 3172 if (warn && !result) { 3173 warning("TransparentHugePages is not supported by the operating system."); 3174 } 3175 3176 return result; 3177 } 3178 3179 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3180 bool result = false; 3181 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3182 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3183 -1, 0); 3184 3185 if (p != MAP_FAILED) { 3186 // We don't know if this really is a huge page or not. 3187 FILE *fp = fopen("/proc/self/maps", "r"); 3188 if (fp) { 3189 while (!feof(fp)) { 3190 char chars[257]; 3191 long x = 0; 3192 if (fgets(chars, sizeof(chars), fp)) { 3193 if (sscanf(chars, "%lx-%*x", &x) == 1 3194 && x == (long)p) { 3195 if (strstr (chars, "hugepage")) { 3196 result = true; 3197 break; 3198 } 3199 } 3200 } 3201 } 3202 fclose(fp); 3203 } 3204 munmap(p, page_size); 3205 } 3206 3207 if (warn && !result) { 3208 warning("HugeTLBFS is not supported by the operating system."); 3209 } 3210 3211 return result; 3212 } 3213 3214 /* 3215 * Set the coredump_filter bits to include largepages in core dump (bit 6) 3216 * 3217 * From the coredump_filter documentation: 3218 * 3219 * - (bit 0) anonymous private memory 3220 * - (bit 1) anonymous shared memory 3221 * - (bit 2) file-backed private memory 3222 * - (bit 3) file-backed shared memory 3223 * - (bit 4) ELF header pages in file-backed private memory areas (it is 3224 * effective only if the bit 2 is cleared) 3225 * - (bit 5) hugetlb private memory 3226 * - (bit 6) hugetlb shared memory 3227 */ 3228 static void set_coredump_filter(void) { 3229 FILE *f; 3230 long cdm; 3231 3232 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3233 return; 3234 } 3235 3236 if (fscanf(f, "%lx", &cdm) != 1) { 3237 fclose(f); 3238 return; 3239 } 3240 3241 rewind(f); 3242 3243 if ((cdm & LARGEPAGES_BIT) == 0) { 3244 cdm |= LARGEPAGES_BIT; 3245 fprintf(f, "%#lx", cdm); 3246 } 3247 3248 fclose(f); 3249 } 3250 3251 // Large page support 3252 3253 static size_t _large_page_size = 0; 3254 3255 size_t os::Linux::find_large_page_size() { 3256 size_t large_page_size = 0; 3257 3258 // large_page_size on Linux is used to round up heap size. x86 uses either 3259 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3260 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3261 // page as large as 256M. 3262 // 3263 // Here we try to figure out page size by parsing /proc/meminfo and looking 3264 // for a line with the following format: 3265 // Hugepagesize: 2048 kB 3266 // 3267 // If we can't determine the value (e.g. /proc is not mounted, or the text 3268 // format has been changed), we'll use the largest page size supported by 3269 // the processor. 3270 3271 #ifndef ZERO 3272 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3273 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3274 #endif // ZERO 3275 3276 FILE *fp = fopen("/proc/meminfo", "r"); 3277 if (fp) { 3278 while (!feof(fp)) { 3279 int x = 0; 3280 char buf[16]; 3281 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3282 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3283 large_page_size = x * K; 3284 break; 3285 } 3286 } else { 3287 // skip to next line 3288 for (;;) { 3289 int ch = fgetc(fp); 3290 if (ch == EOF || ch == (int)'\n') break; 3291 } 3292 } 3293 } 3294 fclose(fp); 3295 } 3296 3297 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3298 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3299 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3300 proper_unit_for_byte_size(large_page_size)); 3301 } 3302 3303 return large_page_size; 3304 } 3305 3306 size_t os::Linux::setup_large_page_size() { 3307 _large_page_size = Linux::find_large_page_size(); 3308 const size_t default_page_size = (size_t)Linux::page_size(); 3309 if (_large_page_size > default_page_size) { 3310 _page_sizes[0] = _large_page_size; 3311 _page_sizes[1] = default_page_size; 3312 _page_sizes[2] = 0; 3313 } 3314 3315 return _large_page_size; 3316 } 3317 3318 bool os::Linux::setup_large_page_type(size_t page_size) { 3319 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3320 FLAG_IS_DEFAULT(UseSHM) && 3321 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3322 3323 // The type of large pages has not been specified by the user. 3324 3325 // Try UseHugeTLBFS and then UseSHM. 3326 UseHugeTLBFS = UseSHM = true; 3327 3328 // Don't try UseTransparentHugePages since there are known 3329 // performance issues with it turned on. This might change in the future. 3330 UseTransparentHugePages = false; 3331 } 3332 3333 if (UseTransparentHugePages) { 3334 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3335 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3336 UseHugeTLBFS = false; 3337 UseSHM = false; 3338 return true; 3339 } 3340 UseTransparentHugePages = false; 3341 } 3342 3343 if (UseHugeTLBFS) { 3344 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3345 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3346 UseSHM = false; 3347 return true; 3348 } 3349 UseHugeTLBFS = false; 3350 } 3351 3352 return UseSHM; 3353 } 3354 3355 void os::large_page_init() { 3356 if (!UseLargePages && 3357 !UseTransparentHugePages && 3358 !UseHugeTLBFS && 3359 !UseSHM) { 3360 // Not using large pages. 3361 return; 3362 } 3363 3364 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3365 // The user explicitly turned off large pages. 3366 // Ignore the rest of the large pages flags. 3367 UseTransparentHugePages = false; 3368 UseHugeTLBFS = false; 3369 UseSHM = false; 3370 return; 3371 } 3372 3373 size_t large_page_size = Linux::setup_large_page_size(); 3374 UseLargePages = Linux::setup_large_page_type(large_page_size); 3375 3376 set_coredump_filter(); 3377 } 3378 3379 #ifndef SHM_HUGETLB 3380 #define SHM_HUGETLB 04000 3381 #endif 3382 3383 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3384 // "exec" is passed in but not used. Creating the shared image for 3385 // the code cache doesn't have an SHM_X executable permission to check. 3386 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3387 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3388 3389 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3390 return NULL; // Fallback to small pages. 3391 } 3392 3393 key_t key = IPC_PRIVATE; 3394 char *addr; 3395 3396 bool warn_on_failure = UseLargePages && 3397 (!FLAG_IS_DEFAULT(UseLargePages) || 3398 !FLAG_IS_DEFAULT(UseSHM) || 3399 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 3400 ); 3401 char msg[128]; 3402 3403 // Create a large shared memory region to attach to based on size. 3404 // Currently, size is the total size of the heap 3405 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3406 if (shmid == -1) { 3407 // Possible reasons for shmget failure: 3408 // 1. shmmax is too small for Java heap. 3409 // > check shmmax value: cat /proc/sys/kernel/shmmax 3410 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3411 // 2. not enough large page memory. 3412 // > check available large pages: cat /proc/meminfo 3413 // > increase amount of large pages: 3414 // echo new_value > /proc/sys/vm/nr_hugepages 3415 // Note 1: different Linux may use different name for this property, 3416 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3417 // Note 2: it's possible there's enough physical memory available but 3418 // they are so fragmented after a long run that they can't 3419 // coalesce into large pages. Try to reserve large pages when 3420 // the system is still "fresh". 3421 if (warn_on_failure) { 3422 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3423 warning("%s", msg); 3424 } 3425 return NULL; 3426 } 3427 3428 // attach to the region 3429 addr = (char*)shmat(shmid, req_addr, 0); 3430 int err = errno; 3431 3432 // Remove shmid. If shmat() is successful, the actual shared memory segment 3433 // will be deleted when it's detached by shmdt() or when the process 3434 // terminates. If shmat() is not successful this will remove the shared 3435 // segment immediately. 3436 shmctl(shmid, IPC_RMID, NULL); 3437 3438 if ((intptr_t)addr == -1) { 3439 if (warn_on_failure) { 3440 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3441 warning("%s", msg); 3442 } 3443 return NULL; 3444 } 3445 3446 return addr; 3447 } 3448 3449 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) { 3450 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3451 3452 bool warn_on_failure = UseLargePages && 3453 (!FLAG_IS_DEFAULT(UseLargePages) || 3454 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3455 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3456 3457 if (warn_on_failure) { 3458 char msg[128]; 3459 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3460 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3461 warning("%s", msg); 3462 } 3463 } 3464 3465 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) { 3466 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3467 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3468 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3469 3470 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3471 char* addr = (char*)::mmap(req_addr, bytes, prot, 3472 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3473 -1, 0); 3474 3475 if (addr == MAP_FAILED) { 3476 warn_on_large_pages_failure(req_addr, bytes, errno); 3477 return NULL; 3478 } 3479 3480 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3481 3482 return addr; 3483 } 3484 3485 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3486 size_t large_page_size = os::large_page_size(); 3487 3488 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3489 3490 // Allocate small pages. 3491 3492 char* start; 3493 if (req_addr != NULL) { 3494 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3495 assert(is_size_aligned(bytes, alignment), "Must be"); 3496 start = os::reserve_memory(bytes, req_addr); 3497 assert(start == NULL || start == req_addr, "Must be"); 3498 } else { 3499 start = os::reserve_memory_aligned(bytes, alignment); 3500 } 3501 3502 if (start == NULL) { 3503 return NULL; 3504 } 3505 3506 assert(is_ptr_aligned(start, alignment), "Must be"); 3507 3508 // os::reserve_memory_special will record this memory area. 3509 // Need to release it here to prevent overlapping reservations. 3510 MemTracker::record_virtual_memory_release((address)start, bytes); 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, mtNone, 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 assert(UseLargePages, "only for large pages"); 3622 3623 MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3624 3625 bool res; 3626 if (UseSHM) { 3627 res = os::Linux::release_memory_special_shm(base, bytes); 3628 } else { 3629 assert(UseHugeTLBFS, "must be"); 3630 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3631 } 3632 3633 if (res) { 3634 tkr.record((address)base, bytes); 3635 } else { 3636 tkr.discard(); 3637 } 3638 3639 return res; 3640 } 3641 3642 size_t os::large_page_size() { 3643 return _large_page_size; 3644 } 3645 3646 // With SysV SHM the entire memory region must be allocated as shared 3647 // memory. 3648 // HugeTLBFS allows application to commit large page memory on demand. 3649 // However, when committing memory with HugeTLBFS fails, the region 3650 // that was supposed to be committed will lose the old reservation 3651 // and allow other threads to steal that memory region. Because of this 3652 // behavior we can't commit HugeTLBFS memory. 3653 bool os::can_commit_large_page_memory() { 3654 return UseTransparentHugePages; 3655 } 3656 3657 bool os::can_execute_large_page_memory() { 3658 return UseTransparentHugePages || UseHugeTLBFS; 3659 } 3660 3661 // Reserve memory at an arbitrary address, only if that area is 3662 // available (and not reserved for something else). 3663 3664 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3665 const int max_tries = 10; 3666 char* base[max_tries]; 3667 size_t size[max_tries]; 3668 const size_t gap = 0x000000; 3669 3670 // Assert only that the size is a multiple of the page size, since 3671 // that's all that mmap requires, and since that's all we really know 3672 // about at this low abstraction level. If we need higher alignment, 3673 // we can either pass an alignment to this method or verify alignment 3674 // in one of the methods further up the call chain. See bug 5044738. 3675 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3676 3677 // Repeatedly allocate blocks until the block is allocated at the 3678 // right spot. Give up after max_tries. Note that reserve_memory() will 3679 // automatically update _highest_vm_reserved_address if the call is 3680 // successful. The variable tracks the highest memory address every reserved 3681 // by JVM. It is used to detect heap-stack collision if running with 3682 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3683 // space than needed, it could confuse the collision detecting code. To 3684 // solve the problem, save current _highest_vm_reserved_address and 3685 // calculate the correct value before return. 3686 address old_highest = _highest_vm_reserved_address; 3687 3688 // Linux mmap allows caller to pass an address as hint; give it a try first, 3689 // if kernel honors the hint then we can return immediately. 3690 char * addr = anon_mmap(requested_addr, bytes, false); 3691 if (addr == requested_addr) { 3692 return requested_addr; 3693 } 3694 3695 if (addr != NULL) { 3696 // mmap() is successful but it fails to reserve at the requested address 3697 anon_munmap(addr, bytes); 3698 } 3699 3700 int i; 3701 for (i = 0; i < max_tries; ++i) { 3702 base[i] = reserve_memory(bytes); 3703 3704 if (base[i] != NULL) { 3705 // Is this the block we wanted? 3706 if (base[i] == requested_addr) { 3707 size[i] = bytes; 3708 break; 3709 } 3710 3711 // Does this overlap the block we wanted? Give back the overlapped 3712 // parts and try again. 3713 3714 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3715 if (top_overlap >= 0 && top_overlap < bytes) { 3716 unmap_memory(base[i], top_overlap); 3717 base[i] += top_overlap; 3718 size[i] = bytes - top_overlap; 3719 } else { 3720 size_t bottom_overlap = base[i] + bytes - requested_addr; 3721 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3722 unmap_memory(requested_addr, bottom_overlap); 3723 size[i] = bytes - bottom_overlap; 3724 } else { 3725 size[i] = bytes; 3726 } 3727 } 3728 } 3729 } 3730 3731 // Give back the unused reserved pieces. 3732 3733 for (int j = 0; j < i; ++j) { 3734 if (base[j] != NULL) { 3735 unmap_memory(base[j], size[j]); 3736 } 3737 } 3738 3739 if (i < max_tries) { 3740 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3741 return requested_addr; 3742 } else { 3743 _highest_vm_reserved_address = old_highest; 3744 return NULL; 3745 } 3746 } 3747 3748 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3749 return ::read(fd, buf, nBytes); 3750 } 3751 3752 // 3753 // Short sleep, direct OS call. 3754 // 3755 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee 3756 // sched_yield(2) will actually give up the CPU: 3757 // 3758 // * Alone on this pariticular CPU, keeps running. 3759 // * Before the introduction of "skip_buddy" with "compat_yield" disabled 3760 // (pre 2.6.39). 3761 // 3762 // So calling this with 0 is an alternative. 3763 // 3764 void os::naked_short_sleep(jlong ms) { 3765 struct timespec req; 3766 3767 assert(ms < 1000, "Un-interruptable sleep, short time use only"); 3768 req.tv_sec = 0; 3769 if (ms > 0) { 3770 req.tv_nsec = (ms % 1000) * 1000000; 3771 } 3772 else { 3773 req.tv_nsec = 1; 3774 } 3775 3776 nanosleep(&req, NULL); 3777 3778 return; 3779 } 3780 3781 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3782 void os::infinite_sleep() { 3783 while (true) { // sleep forever ... 3784 ::sleep(100); // ... 100 seconds at a time 3785 } 3786 } 3787 3788 // Used to convert frequent JVM_Yield() to nops 3789 bool os::dont_yield() { 3790 return DontYieldALot; 3791 } 3792 3793 void os::yield() { 3794 sched_yield(); 3795 } 3796 3797 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN; } 3798 3799 void os::yield_all() { 3800 // Yields to all threads, including threads with lower priorities 3801 // Threads on Linux are all with same priority. The Solaris style 3802 // os::yield_all() with nanosleep(1ms) is not necessary. 3803 sched_yield(); 3804 } 3805 3806 //////////////////////////////////////////////////////////////////////////////// 3807 // thread priority support 3808 3809 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3810 // only supports dynamic priority, static priority must be zero. For real-time 3811 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3812 // However, for large multi-threaded applications, SCHED_RR is not only slower 3813 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3814 // of 5 runs - Sep 2005). 3815 // 3816 // The following code actually changes the niceness of kernel-thread/LWP. It 3817 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3818 // not the entire user process, and user level threads are 1:1 mapped to kernel 3819 // threads. It has always been the case, but could change in the future. For 3820 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3821 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3822 3823 int os::java_to_os_priority[CriticalPriority + 1] = { 3824 19, // 0 Entry should never be used 3825 3826 4, // 1 MinPriority 3827 3, // 2 3828 2, // 3 3829 3830 1, // 4 3831 0, // 5 NormPriority 3832 -1, // 6 3833 3834 -2, // 7 3835 -3, // 8 3836 -4, // 9 NearMaxPriority 3837 3838 -5, // 10 MaxPriority 3839 3840 -5 // 11 CriticalPriority 3841 }; 3842 3843 static int prio_init() { 3844 if (ThreadPriorityPolicy == 1) { 3845 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3846 // if effective uid is not root. Perhaps, a more elegant way of doing 3847 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3848 if (geteuid() != 0) { 3849 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3850 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3851 } 3852 ThreadPriorityPolicy = 0; 3853 } 3854 } 3855 if (UseCriticalJavaThreadPriority) { 3856 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3857 } 3858 return 0; 3859 } 3860 3861 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3862 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK; 3863 3864 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3865 return (ret == 0) ? OS_OK : OS_ERR; 3866 } 3867 3868 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3869 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) { 3870 *priority_ptr = java_to_os_priority[NormPriority]; 3871 return OS_OK; 3872 } 3873 3874 errno = 0; 3875 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3876 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3877 } 3878 3879 // Hint to the underlying OS that a task switch would not be good. 3880 // Void return because it's a hint and can fail. 3881 void os::hint_no_preempt() {} 3882 3883 //////////////////////////////////////////////////////////////////////////////// 3884 // suspend/resume support 3885 3886 // the low-level signal-based suspend/resume support is a remnant from the 3887 // old VM-suspension that used to be for java-suspension, safepoints etc, 3888 // within hotspot. Now there is a single use-case for this: 3889 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3890 // that runs in the watcher thread. 3891 // The remaining code is greatly simplified from the more general suspension 3892 // code that used to be used. 3893 // 3894 // The protocol is quite simple: 3895 // - suspend: 3896 // - sends a signal to the target thread 3897 // - polls the suspend state of the osthread using a yield loop 3898 // - target thread signal handler (SR_handler) sets suspend state 3899 // and blocks in sigsuspend until continued 3900 // - resume: 3901 // - sets target osthread state to continue 3902 // - sends signal to end the sigsuspend loop in the SR_handler 3903 // 3904 // Note that the SR_lock plays no role in this suspend/resume protocol. 3905 // 3906 3907 static void resume_clear_context(OSThread *osthread) { 3908 osthread->set_ucontext(NULL); 3909 osthread->set_siginfo(NULL); 3910 } 3911 3912 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 3913 osthread->set_ucontext(context); 3914 osthread->set_siginfo(siginfo); 3915 } 3916 3917 // 3918 // Handler function invoked when a thread's execution is suspended or 3919 // resumed. We have to be careful that only async-safe functions are 3920 // called here (Note: most pthread functions are not async safe and 3921 // should be avoided.) 3922 // 3923 // Note: sigwait() is a more natural fit than sigsuspend() from an 3924 // interface point of view, but sigwait() prevents the signal hander 3925 // from being run. libpthread would get very confused by not having 3926 // its signal handlers run and prevents sigwait()'s use with the 3927 // mutex granting granting signal. 3928 // 3929 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 3930 // 3931 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3932 // Save and restore errno to avoid confusing native code with EINTR 3933 // after sigsuspend. 3934 int old_errno = errno; 3935 3936 Thread* thread = Thread::current(); 3937 OSThread* osthread = thread->osthread(); 3938 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 3939 3940 os::SuspendResume::State current = osthread->sr.state(); 3941 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 3942 suspend_save_context(osthread, siginfo, context); 3943 3944 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 3945 os::SuspendResume::State state = osthread->sr.suspended(); 3946 if (state == os::SuspendResume::SR_SUSPENDED) { 3947 sigset_t suspend_set; // signals for sigsuspend() 3948 3949 // get current set of blocked signals and unblock resume signal 3950 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3951 sigdelset(&suspend_set, SR_signum); 3952 3953 sr_semaphore.signal(); 3954 // wait here until we are resumed 3955 while (1) { 3956 sigsuspend(&suspend_set); 3957 3958 os::SuspendResume::State result = osthread->sr.running(); 3959 if (result == os::SuspendResume::SR_RUNNING) { 3960 sr_semaphore.signal(); 3961 break; 3962 } 3963 } 3964 3965 } else if (state == os::SuspendResume::SR_RUNNING) { 3966 // request was cancelled, continue 3967 } else { 3968 ShouldNotReachHere(); 3969 } 3970 3971 resume_clear_context(osthread); 3972 } else if (current == os::SuspendResume::SR_RUNNING) { 3973 // request was cancelled, continue 3974 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 3975 // ignore 3976 } else { 3977 // ignore 3978 } 3979 3980 errno = old_errno; 3981 } 3982 3983 3984 static int SR_initialize() { 3985 struct sigaction act; 3986 char *s; 3987 /* Get signal number to use for suspend/resume */ 3988 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 3989 int sig = ::strtol(s, 0, 10); 3990 if (sig > 0 || sig < _NSIG) { 3991 SR_signum = sig; 3992 } 3993 } 3994 3995 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 3996 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 3997 3998 sigemptyset(&SR_sigset); 3999 sigaddset(&SR_sigset, SR_signum); 4000 4001 /* Set up signal handler for suspend/resume */ 4002 act.sa_flags = SA_RESTART|SA_SIGINFO; 4003 act.sa_handler = (void (*)(int)) SR_handler; 4004 4005 // SR_signum is blocked by default. 4006 // 4528190 - We also need to block pthread restart signal (32 on all 4007 // supported Linux platforms). Note that LinuxThreads need to block 4008 // this signal for all threads to work properly. So we don't have 4009 // to use hard-coded signal number when setting up the mask. 4010 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4011 4012 if (sigaction(SR_signum, &act, 0) == -1) { 4013 return -1; 4014 } 4015 4016 // Save signal flag 4017 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4018 return 0; 4019 } 4020 4021 static int sr_notify(OSThread* osthread) { 4022 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4023 assert_status(status == 0, status, "pthread_kill"); 4024 return status; 4025 } 4026 4027 // "Randomly" selected value for how long we want to spin 4028 // before bailing out on suspending a thread, also how often 4029 // we send a signal to a thread we want to resume 4030 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4031 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4032 4033 // returns true on success and false on error - really an error is fatal 4034 // but this seems the normal response to library errors 4035 static bool do_suspend(OSThread* osthread) { 4036 assert(osthread->sr.is_running(), "thread should be running"); 4037 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4038 4039 // mark as suspended and send signal 4040 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4041 // failed to switch, state wasn't running? 4042 ShouldNotReachHere(); 4043 return false; 4044 } 4045 4046 if (sr_notify(osthread) != 0) { 4047 ShouldNotReachHere(); 4048 } 4049 4050 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4051 while (true) { 4052 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4053 break; 4054 } else { 4055 // timeout 4056 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4057 if (cancelled == os::SuspendResume::SR_RUNNING) { 4058 return false; 4059 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4060 // make sure that we consume the signal on the semaphore as well 4061 sr_semaphore.wait(); 4062 break; 4063 } else { 4064 ShouldNotReachHere(); 4065 return false; 4066 } 4067 } 4068 } 4069 4070 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4071 return true; 4072 } 4073 4074 static void do_resume(OSThread* osthread) { 4075 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4076 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4077 4078 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4079 // failed to switch to WAKEUP_REQUEST 4080 ShouldNotReachHere(); 4081 return; 4082 } 4083 4084 while (true) { 4085 if (sr_notify(osthread) == 0) { 4086 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4087 if (osthread->sr.is_running()) { 4088 return; 4089 } 4090 } 4091 } else { 4092 ShouldNotReachHere(); 4093 } 4094 } 4095 4096 guarantee(osthread->sr.is_running(), "Must be running!"); 4097 } 4098 4099 /////////////////////////////////////////////////////////////////////////////////// 4100 // signal handling (except suspend/resume) 4101 4102 // This routine may be used by user applications as a "hook" to catch signals. 4103 // The user-defined signal handler must pass unrecognized signals to this 4104 // routine, and if it returns true (non-zero), then the signal handler must 4105 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4106 // routine will never retun false (zero), but instead will execute a VM panic 4107 // routine kill the process. 4108 // 4109 // If this routine returns false, it is OK to call it again. This allows 4110 // the user-defined signal handler to perform checks either before or after 4111 // the VM performs its own checks. Naturally, the user code would be making 4112 // a serious error if it tried to handle an exception (such as a null check 4113 // or breakpoint) that the VM was generating for its own correct operation. 4114 // 4115 // This routine may recognize any of the following kinds of signals: 4116 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4117 // It should be consulted by handlers for any of those signals. 4118 // 4119 // The caller of this routine must pass in the three arguments supplied 4120 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4121 // field of the structure passed to sigaction(). This routine assumes that 4122 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4123 // 4124 // Note that the VM will print warnings if it detects conflicting signal 4125 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4126 // 4127 extern "C" JNIEXPORT int 4128 JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 4129 void* ucontext, int abort_if_unrecognized); 4130 4131 void signalHandler(int sig, siginfo_t* info, void* uc) { 4132 assert(info != NULL && uc != NULL, "it must be old kernel"); 4133 int orig_errno = errno; // Preserve errno value over signal handler. 4134 JVM_handle_linux_signal(sig, info, uc, true); 4135 errno = orig_errno; 4136 } 4137 4138 4139 // This boolean allows users to forward their own non-matching signals 4140 // to JVM_handle_linux_signal, harmlessly. 4141 bool os::Linux::signal_handlers_are_installed = false; 4142 4143 // For signal-chaining 4144 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4145 unsigned int os::Linux::sigs = 0; 4146 bool os::Linux::libjsig_is_loaded = false; 4147 typedef struct sigaction *(*get_signal_t)(int); 4148 get_signal_t os::Linux::get_signal_action = NULL; 4149 4150 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4151 struct sigaction *actp = NULL; 4152 4153 if (libjsig_is_loaded) { 4154 // Retrieve the old signal handler from libjsig 4155 actp = (*get_signal_action)(sig); 4156 } 4157 if (actp == NULL) { 4158 // Retrieve the preinstalled signal handler from jvm 4159 actp = get_preinstalled_handler(sig); 4160 } 4161 4162 return actp; 4163 } 4164 4165 static bool call_chained_handler(struct sigaction *actp, int sig, 4166 siginfo_t *siginfo, void *context) { 4167 // Call the old signal handler 4168 if (actp->sa_handler == SIG_DFL) { 4169 // It's more reasonable to let jvm treat it as an unexpected exception 4170 // instead of taking the default action. 4171 return false; 4172 } else if (actp->sa_handler != SIG_IGN) { 4173 if ((actp->sa_flags & SA_NODEFER) == 0) { 4174 // automaticlly block the signal 4175 sigaddset(&(actp->sa_mask), sig); 4176 } 4177 4178 sa_handler_t hand; 4179 sa_sigaction_t sa; 4180 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4181 // retrieve the chained handler 4182 if (siginfo_flag_set) { 4183 sa = actp->sa_sigaction; 4184 } else { 4185 hand = actp->sa_handler; 4186 } 4187 4188 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4189 actp->sa_handler = SIG_DFL; 4190 } 4191 4192 // try to honor the signal mask 4193 sigset_t oset; 4194 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4195 4196 // call into the chained handler 4197 if (siginfo_flag_set) { 4198 (*sa)(sig, siginfo, context); 4199 } else { 4200 (*hand)(sig); 4201 } 4202 4203 // restore the signal mask 4204 pthread_sigmask(SIG_SETMASK, &oset, 0); 4205 } 4206 // Tell jvm's signal handler the signal is taken care of. 4207 return true; 4208 } 4209 4210 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4211 bool chained = false; 4212 // signal-chaining 4213 if (UseSignalChaining) { 4214 struct sigaction *actp = get_chained_signal_action(sig); 4215 if (actp != NULL) { 4216 chained = call_chained_handler(actp, sig, siginfo, context); 4217 } 4218 } 4219 return chained; 4220 } 4221 4222 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4223 if ((((unsigned int)1 << sig) & sigs) != 0) { 4224 return &sigact[sig]; 4225 } 4226 return NULL; 4227 } 4228 4229 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4230 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4231 sigact[sig] = oldAct; 4232 sigs |= (unsigned int)1 << sig; 4233 } 4234 4235 // for diagnostic 4236 int os::Linux::sigflags[MAXSIGNUM]; 4237 4238 int os::Linux::get_our_sigflags(int sig) { 4239 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4240 return sigflags[sig]; 4241 } 4242 4243 void os::Linux::set_our_sigflags(int sig, int flags) { 4244 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4245 sigflags[sig] = flags; 4246 } 4247 4248 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4249 // Check for overwrite. 4250 struct sigaction oldAct; 4251 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4252 4253 void* oldhand = oldAct.sa_sigaction 4254 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4255 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4256 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4257 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4258 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4259 if (AllowUserSignalHandlers || !set_installed) { 4260 // Do not overwrite; user takes responsibility to forward to us. 4261 return; 4262 } else if (UseSignalChaining) { 4263 // save the old handler in jvm 4264 save_preinstalled_handler(sig, oldAct); 4265 // libjsig also interposes the sigaction() call below and saves the 4266 // old sigaction on it own. 4267 } else { 4268 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4269 "%#lx for signal %d.", (long)oldhand, sig)); 4270 } 4271 } 4272 4273 struct sigaction sigAct; 4274 sigfillset(&(sigAct.sa_mask)); 4275 sigAct.sa_handler = SIG_DFL; 4276 if (!set_installed) { 4277 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4278 } else { 4279 sigAct.sa_sigaction = signalHandler; 4280 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4281 } 4282 // Save flags, which are set by ours 4283 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4284 sigflags[sig] = sigAct.sa_flags; 4285 4286 int ret = sigaction(sig, &sigAct, &oldAct); 4287 assert(ret == 0, "check"); 4288 4289 void* oldhand2 = oldAct.sa_sigaction 4290 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4291 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4292 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4293 } 4294 4295 // install signal handlers for signals that HotSpot needs to 4296 // handle in order to support Java-level exception handling. 4297 4298 void os::Linux::install_signal_handlers() { 4299 if (!signal_handlers_are_installed) { 4300 signal_handlers_are_installed = true; 4301 4302 // signal-chaining 4303 typedef void (*signal_setting_t)(); 4304 signal_setting_t begin_signal_setting = NULL; 4305 signal_setting_t end_signal_setting = NULL; 4306 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4307 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4308 if (begin_signal_setting != NULL) { 4309 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4310 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4311 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4312 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4313 libjsig_is_loaded = true; 4314 assert(UseSignalChaining, "should enable signal-chaining"); 4315 } 4316 if (libjsig_is_loaded) { 4317 // Tell libjsig jvm is setting signal handlers 4318 (*begin_signal_setting)(); 4319 } 4320 4321 set_signal_handler(SIGSEGV, true); 4322 set_signal_handler(SIGPIPE, true); 4323 set_signal_handler(SIGBUS, true); 4324 set_signal_handler(SIGILL, true); 4325 set_signal_handler(SIGFPE, true); 4326 #if defined(PPC64) 4327 set_signal_handler(SIGTRAP, true); 4328 #endif 4329 set_signal_handler(SIGXFSZ, true); 4330 4331 if (libjsig_is_loaded) { 4332 // Tell libjsig jvm finishes setting signal handlers 4333 (*end_signal_setting)(); 4334 } 4335 4336 // We don't activate signal checker if libjsig is in place, we trust ourselves 4337 // and if UserSignalHandler is installed all bets are off. 4338 // Log that signal checking is off only if -verbose:jni is specified. 4339 if (CheckJNICalls) { 4340 if (libjsig_is_loaded) { 4341 if (PrintJNIResolving) { 4342 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4343 } 4344 check_signals = false; 4345 } 4346 if (AllowUserSignalHandlers) { 4347 if (PrintJNIResolving) { 4348 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4349 } 4350 check_signals = false; 4351 } 4352 } 4353 } 4354 } 4355 4356 // This is the fastest way to get thread cpu time on Linux. 4357 // Returns cpu time (user+sys) for any thread, not only for current. 4358 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4359 // It might work on 2.6.10+ with a special kernel/glibc patch. 4360 // For reference, please, see IEEE Std 1003.1-2004: 4361 // http://www.unix.org/single_unix_specification 4362 4363 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4364 struct timespec tp; 4365 int rc = os::Linux::clock_gettime(clockid, &tp); 4366 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4367 4368 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4369 } 4370 4371 ///// 4372 // glibc on Linux platform uses non-documented flag 4373 // to indicate, that some special sort of signal 4374 // trampoline is used. 4375 // We will never set this flag, and we should 4376 // ignore this flag in our diagnostic 4377 #ifdef SIGNIFICANT_SIGNAL_MASK 4378 #undef SIGNIFICANT_SIGNAL_MASK 4379 #endif 4380 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4381 4382 static const char* get_signal_handler_name(address handler, 4383 char* buf, int buflen) { 4384 int offset; 4385 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4386 if (found) { 4387 // skip directory names 4388 const char *p1, *p2; 4389 p1 = buf; 4390 size_t len = strlen(os::file_separator()); 4391 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4392 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4393 } else { 4394 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4395 } 4396 return buf; 4397 } 4398 4399 static void print_signal_handler(outputStream* st, int sig, 4400 char* buf, size_t buflen) { 4401 struct sigaction sa; 4402 4403 sigaction(sig, NULL, &sa); 4404 4405 // See comment for SIGNIFICANT_SIGNAL_MASK define 4406 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4407 4408 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4409 4410 address handler = (sa.sa_flags & SA_SIGINFO) 4411 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4412 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4413 4414 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4415 st->print("SIG_DFL"); 4416 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4417 st->print("SIG_IGN"); 4418 } else { 4419 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4420 } 4421 4422 st->print(", sa_mask[0]="); 4423 os::Posix::print_signal_set_short(st, &sa.sa_mask); 4424 4425 address rh = VMError::get_resetted_sighandler(sig); 4426 // May be, handler was resetted by VMError? 4427 if (rh != NULL) { 4428 handler = rh; 4429 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4430 } 4431 4432 st->print(", sa_flags="); 4433 os::Posix::print_sa_flags(st, sa.sa_flags); 4434 4435 // Check: is it our handler? 4436 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4437 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4438 // It is our signal handler 4439 // check for flags, reset system-used one! 4440 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4441 st->print( 4442 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4443 os::Linux::get_our_sigflags(sig)); 4444 } 4445 } 4446 st->cr(); 4447 } 4448 4449 4450 #define DO_SIGNAL_CHECK(sig) \ 4451 if (!sigismember(&check_signal_done, sig)) \ 4452 os::Linux::check_signal_handler(sig) 4453 4454 // This method is a periodic task to check for misbehaving JNI applications 4455 // under CheckJNI, we can add any periodic checks here 4456 4457 void os::run_periodic_checks() { 4458 4459 if (check_signals == false) return; 4460 4461 // SEGV and BUS if overridden could potentially prevent 4462 // generation of hs*.log in the event of a crash, debugging 4463 // such a case can be very challenging, so we absolutely 4464 // check the following for a good measure: 4465 DO_SIGNAL_CHECK(SIGSEGV); 4466 DO_SIGNAL_CHECK(SIGILL); 4467 DO_SIGNAL_CHECK(SIGFPE); 4468 DO_SIGNAL_CHECK(SIGBUS); 4469 DO_SIGNAL_CHECK(SIGPIPE); 4470 DO_SIGNAL_CHECK(SIGXFSZ); 4471 #if defined(PPC64) 4472 DO_SIGNAL_CHECK(SIGTRAP); 4473 #endif 4474 4475 // ReduceSignalUsage allows the user to override these handlers 4476 // see comments at the very top and jvm_solaris.h 4477 if (!ReduceSignalUsage) { 4478 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4479 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4480 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4481 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4482 } 4483 4484 DO_SIGNAL_CHECK(SR_signum); 4485 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4486 } 4487 4488 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4489 4490 static os_sigaction_t os_sigaction = NULL; 4491 4492 void os::Linux::check_signal_handler(int sig) { 4493 char buf[O_BUFLEN]; 4494 address jvmHandler = NULL; 4495 4496 4497 struct sigaction act; 4498 if (os_sigaction == NULL) { 4499 // only trust the default sigaction, in case it has been interposed 4500 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4501 if (os_sigaction == NULL) return; 4502 } 4503 4504 os_sigaction(sig, (struct sigaction*)NULL, &act); 4505 4506 4507 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4508 4509 address thisHandler = (act.sa_flags & SA_SIGINFO) 4510 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4511 : CAST_FROM_FN_PTR(address, act.sa_handler); 4512 4513 4514 switch (sig) { 4515 case SIGSEGV: 4516 case SIGBUS: 4517 case SIGFPE: 4518 case SIGPIPE: 4519 case SIGILL: 4520 case SIGXFSZ: 4521 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4522 break; 4523 4524 case SHUTDOWN1_SIGNAL: 4525 case SHUTDOWN2_SIGNAL: 4526 case SHUTDOWN3_SIGNAL: 4527 case BREAK_SIGNAL: 4528 jvmHandler = (address)user_handler(); 4529 break; 4530 4531 case INTERRUPT_SIGNAL: 4532 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4533 break; 4534 4535 default: 4536 if (sig == SR_signum) { 4537 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4538 } else { 4539 return; 4540 } 4541 break; 4542 } 4543 4544 if (thisHandler != jvmHandler) { 4545 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4546 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4547 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4548 // No need to check this sig any longer 4549 sigaddset(&check_signal_done, sig); 4550 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN 4551 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) { 4552 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell", 4553 exception_name(sig, buf, O_BUFLEN)); 4554 } 4555 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4556 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4557 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4558 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4559 // No need to check this sig any longer 4560 sigaddset(&check_signal_done, sig); 4561 } 4562 4563 // Dump all the signal 4564 if (sigismember(&check_signal_done, sig)) { 4565 print_signal_handlers(tty, buf, O_BUFLEN); 4566 } 4567 } 4568 4569 extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 4570 4571 extern bool signal_name(int signo, char* buf, size_t len); 4572 4573 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4574 if (0 < exception_code && exception_code <= SIGRTMAX) { 4575 // signal 4576 if (!signal_name(exception_code, buf, size)) { 4577 jio_snprintf(buf, size, "SIG%d", exception_code); 4578 } 4579 return buf; 4580 } else { 4581 return NULL; 4582 } 4583 } 4584 4585 // this is called _before_ the most of global arguments have been parsed 4586 void os::init(void) { 4587 char dummy; /* used to get a guess on initial stack address */ 4588 // first_hrtime = gethrtime(); 4589 4590 // With LinuxThreads the JavaMain thread pid (primordial thread) 4591 // is different than the pid of the java launcher thread. 4592 // So, on Linux, the launcher thread pid is passed to the VM 4593 // via the sun.java.launcher.pid property. 4594 // Use this property instead of getpid() if it was correctly passed. 4595 // See bug 6351349. 4596 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4597 4598 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4599 4600 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4601 4602 init_random(1234567); 4603 4604 ThreadCritical::initialize(); 4605 4606 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4607 if (Linux::page_size() == -1) { 4608 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4609 strerror(errno))); 4610 } 4611 init_page_sizes((size_t) Linux::page_size()); 4612 4613 Linux::initialize_system_info(); 4614 4615 // main_thread points to the aboriginal thread 4616 Linux::_main_thread = pthread_self(); 4617 4618 Linux::clock_init(); 4619 initial_time_count = javaTimeNanos(); 4620 4621 // pthread_condattr initialization for monotonic clock 4622 int status; 4623 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4624 if ((status = pthread_condattr_init(_condattr)) != 0) { 4625 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4626 } 4627 // Only set the clock if CLOCK_MONOTONIC is available 4628 if (os::supports_monotonic_clock()) { 4629 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4630 if (status == EINVAL) { 4631 warning("Unable to use monotonic clock with relative timed-waits" \ 4632 " - changes to the time-of-day clock may have adverse affects"); 4633 } else { 4634 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4635 } 4636 } 4637 } 4638 // else it defaults to CLOCK_REALTIME 4639 4640 pthread_mutex_init(&dl_mutex, NULL); 4641 4642 // If the pagesize of the VM is greater than 8K determine the appropriate 4643 // number of initial guard pages. The user can change this with the 4644 // command line arguments, if needed. 4645 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4646 StackYellowPages = 1; 4647 StackRedPages = 1; 4648 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4649 } 4650 } 4651 4652 // To install functions for atexit system call 4653 extern "C" { 4654 static void perfMemory_exit_helper() { 4655 perfMemory_exit(); 4656 } 4657 } 4658 4659 // this is called _after_ the global arguments have been parsed 4660 jint os::init_2(void) 4661 { 4662 Linux::fast_thread_clock_init(); 4663 4664 // Allocate a single page and mark it as readable for safepoint polling 4665 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4666 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page"); 4667 4668 os::set_polling_page(polling_page); 4669 4670 #ifndef PRODUCT 4671 if (Verbose && PrintMiscellaneous) 4672 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 4673 #endif 4674 4675 if (!UseMembar) { 4676 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4677 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4678 os::set_memory_serialize_page(mem_serialize_page); 4679 4680 #ifndef PRODUCT 4681 if (Verbose && PrintMiscellaneous) 4682 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 4683 #endif 4684 } 4685 4686 // initialize suspend/resume support - must do this before signal_sets_init() 4687 if (SR_initialize() != 0) { 4688 perror("SR_initialize failed"); 4689 return JNI_ERR; 4690 } 4691 4692 Linux::signal_sets_init(); 4693 Linux::install_signal_handlers(); 4694 4695 // Check minimum allowable stack size for thread creation and to initialize 4696 // the java system classes, including StackOverflowError - depends on page 4697 // size. Add a page for compiler2 recursion in main thread. 4698 // Add in 2*BytesPerWord times page size to account for VM stack during 4699 // class initialization depending on 32 or 64 bit VM. 4700 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4701 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4702 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4703 4704 size_t threadStackSizeInBytes = ThreadStackSize * K; 4705 if (threadStackSizeInBytes != 0 && 4706 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4707 tty->print_cr("\nThe stack size specified is too small, " 4708 "Specify at least %dk", 4709 os::Linux::min_stack_allowed/ K); 4710 return JNI_ERR; 4711 } 4712 4713 // Make the stack size a multiple of the page size so that 4714 // the yellow/red zones can be guarded. 4715 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4716 vm_page_size())); 4717 4718 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4719 4720 #if defined(IA32) 4721 workaround_expand_exec_shield_cs_limit(); 4722 #endif 4723 4724 Linux::libpthread_init(); 4725 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4726 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4727 Linux::glibc_version(), Linux::libpthread_version(), 4728 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4729 } 4730 4731 if (UseNUMA) { 4732 if (!Linux::libnuma_init()) { 4733 UseNUMA = false; 4734 } else { 4735 if ((Linux::numa_max_node() < 1)) { 4736 // There's only one node(they start from 0), disable NUMA. 4737 UseNUMA = false; 4738 } 4739 } 4740 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4741 // we can make the adaptive lgrp chunk resizing work. If the user specified 4742 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4743 // disable adaptive resizing. 4744 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4745 if (FLAG_IS_DEFAULT(UseNUMA)) { 4746 UseNUMA = false; 4747 } else { 4748 if (FLAG_IS_DEFAULT(UseLargePages) && 4749 FLAG_IS_DEFAULT(UseSHM) && 4750 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4751 UseLargePages = false; 4752 } else { 4753 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4754 UseAdaptiveSizePolicy = false; 4755 UseAdaptiveNUMAChunkSizing = false; 4756 } 4757 } 4758 } 4759 if (!UseNUMA && ForceNUMA) { 4760 UseNUMA = true; 4761 } 4762 } 4763 4764 if (MaxFDLimit) { 4765 // set the number of file descriptors to max. print out error 4766 // if getrlimit/setrlimit fails but continue regardless. 4767 struct rlimit nbr_files; 4768 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4769 if (status != 0) { 4770 if (PrintMiscellaneous && (Verbose || WizardMode)) 4771 perror("os::init_2 getrlimit failed"); 4772 } else { 4773 nbr_files.rlim_cur = nbr_files.rlim_max; 4774 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4775 if (status != 0) { 4776 if (PrintMiscellaneous && (Verbose || WizardMode)) 4777 perror("os::init_2 setrlimit failed"); 4778 } 4779 } 4780 } 4781 4782 // Initialize lock used to serialize thread creation (see os::create_thread) 4783 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4784 4785 // at-exit methods are called in the reverse order of their registration. 4786 // atexit functions are called on return from main or as a result of a 4787 // call to exit(3C). There can be only 32 of these functions registered 4788 // and atexit() does not set errno. 4789 4790 if (PerfAllowAtExitRegistration) { 4791 // only register atexit functions if PerfAllowAtExitRegistration is set. 4792 // atexit functions can be delayed until process exit time, which 4793 // can be problematic for embedded VM situations. Embedded VMs should 4794 // call DestroyJavaVM() to assure that VM resources are released. 4795 4796 // note: perfMemory_exit_helper atexit function may be removed in 4797 // the future if the appropriate cleanup code can be added to the 4798 // VM_Exit VMOperation's doit method. 4799 if (atexit(perfMemory_exit_helper) != 0) { 4800 warning("os::init_2 atexit(perfMemory_exit_helper) failed"); 4801 } 4802 } 4803 4804 // initialize thread priority policy 4805 prio_init(); 4806 4807 return JNI_OK; 4808 } 4809 4810 // this is called at the end of vm_initialization 4811 void os::init_3(void) { 4812 #ifdef JAVASE_EMBEDDED 4813 // Start the MemNotifyThread 4814 if (LowMemoryProtection) { 4815 MemNotifyThread::start(); 4816 } 4817 return; 4818 #endif 4819 } 4820 4821 // Mark the polling page as unreadable 4822 void os::make_polling_page_unreadable(void) { 4823 if (!guard_memory((char*)_polling_page, Linux::page_size())) 4824 fatal("Could not disable polling page"); 4825 }; 4826 4827 // Mark the polling page as readable 4828 void os::make_polling_page_readable(void) { 4829 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4830 fatal("Could not enable polling page"); 4831 } 4832 }; 4833 4834 int os::active_processor_count() { 4835 // Linux doesn't yet have a (official) notion of processor sets, 4836 // so just return the number of online processors. 4837 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4838 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4839 return online_cpus; 4840 } 4841 4842 void os::set_native_thread_name(const char *name) { 4843 // Not yet implemented. 4844 return; 4845 } 4846 4847 bool os::distribute_processes(uint length, uint* distribution) { 4848 // Not yet implemented. 4849 return false; 4850 } 4851 4852 bool os::bind_to_processor(uint processor_id) { 4853 // Not yet implemented. 4854 return false; 4855 } 4856 4857 /// 4858 4859 void os::SuspendedThreadTask::internal_do_task() { 4860 if (do_suspend(_thread->osthread())) { 4861 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4862 do_task(context); 4863 do_resume(_thread->osthread()); 4864 } 4865 } 4866 4867 class PcFetcher : public os::SuspendedThreadTask { 4868 public: 4869 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4870 ExtendedPC result(); 4871 protected: 4872 void do_task(const os::SuspendedThreadTaskContext& context); 4873 private: 4874 ExtendedPC _epc; 4875 }; 4876 4877 ExtendedPC PcFetcher::result() { 4878 guarantee(is_done(), "task is not done yet."); 4879 return _epc; 4880 } 4881 4882 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 4883 Thread* thread = context.thread(); 4884 OSThread* osthread = thread->osthread(); 4885 if (osthread->ucontext() != NULL) { 4886 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 4887 } else { 4888 // NULL context is unexpected, double-check this is the VMThread 4889 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4890 } 4891 } 4892 4893 // Suspends the target using the signal mechanism and then grabs the PC before 4894 // resuming the target. Used by the flat-profiler only 4895 ExtendedPC os::get_thread_pc(Thread* thread) { 4896 // Make sure that it is called by the watcher for the VMThread 4897 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4898 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4899 4900 PcFetcher fetcher(thread); 4901 fetcher.run(); 4902 return fetcher.result(); 4903 } 4904 4905 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 4906 { 4907 if (is_NPTL()) { 4908 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4909 } else { 4910 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4911 // word back to default 64bit precision if condvar is signaled. Java 4912 // wants 53bit precision. Save and restore current value. 4913 int fpu = get_fpu_control_word(); 4914 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4915 set_fpu_control_word(fpu); 4916 return status; 4917 } 4918 } 4919 4920 //////////////////////////////////////////////////////////////////////////////// 4921 // debug support 4922 4923 bool os::find(address addr, outputStream* st) { 4924 Dl_info dlinfo; 4925 memset(&dlinfo, 0, sizeof(dlinfo)); 4926 if (dladdr(addr, &dlinfo) != 0) { 4927 st->print(PTR_FORMAT ": ", addr); 4928 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 4929 st->print("%s+%#x", dlinfo.dli_sname, 4930 addr - (intptr_t)dlinfo.dli_saddr); 4931 } else if (dlinfo.dli_fbase != NULL) { 4932 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4933 } else { 4934 st->print("<absolute address>"); 4935 } 4936 if (dlinfo.dli_fname != NULL) { 4937 st->print(" in %s", dlinfo.dli_fname); 4938 } 4939 if (dlinfo.dli_fbase != NULL) { 4940 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4941 } 4942 st->cr(); 4943 4944 if (Verbose) { 4945 // decode some bytes around the PC 4946 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 4947 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 4948 address lowest = (address) dlinfo.dli_sname; 4949 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4950 if (begin < lowest) begin = lowest; 4951 Dl_info dlinfo2; 4952 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 4953 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 4954 end = (address) dlinfo2.dli_saddr; 4955 Disassembler::decode(begin, end, st); 4956 } 4957 return true; 4958 } 4959 return false; 4960 } 4961 4962 //////////////////////////////////////////////////////////////////////////////// 4963 // misc 4964 4965 // This does not do anything on Linux. This is basically a hook for being 4966 // able to use structured exception handling (thread-local exception filters) 4967 // on, e.g., Win32. 4968 void 4969 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 4970 JavaCallArguments* args, Thread* thread) { 4971 f(value, method, args, thread); 4972 } 4973 4974 void os::print_statistics() { 4975 } 4976 4977 int os::message_box(const char* title, const char* message) { 4978 int i; 4979 fdStream err(defaultStream::error_fd()); 4980 for (i = 0; i < 78; i++) err.print_raw("="); 4981 err.cr(); 4982 err.print_raw_cr(title); 4983 for (i = 0; i < 78; i++) err.print_raw("-"); 4984 err.cr(); 4985 err.print_raw_cr(message); 4986 for (i = 0; i < 78; i++) err.print_raw("="); 4987 err.cr(); 4988 4989 char buf[16]; 4990 // Prevent process from exiting upon "read error" without consuming all CPU 4991 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 4992 4993 return buf[0] == 'y' || buf[0] == 'Y'; 4994 } 4995 4996 int os::stat(const char *path, struct stat *sbuf) { 4997 char pathbuf[MAX_PATH]; 4998 if (strlen(path) > MAX_PATH - 1) { 4999 errno = ENAMETOOLONG; 5000 return -1; 5001 } 5002 os::native_path(strcpy(pathbuf, path)); 5003 return ::stat(pathbuf, sbuf); 5004 } 5005 5006 bool os::check_heap(bool force) { 5007 return true; 5008 } 5009 5010 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 5011 return ::vsnprintf(buf, count, format, args); 5012 } 5013 5014 // Is a (classpath) directory empty? 5015 bool os::dir_is_empty(const char* path) { 5016 DIR *dir = NULL; 5017 struct dirent *ptr; 5018 5019 dir = opendir(path); 5020 if (dir == NULL) return true; 5021 5022 /* Scan the directory */ 5023 bool result = true; 5024 char buf[sizeof(struct dirent) + MAX_PATH]; 5025 while (result && (ptr = ::readdir(dir)) != NULL) { 5026 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5027 result = false; 5028 } 5029 } 5030 closedir(dir); 5031 return result; 5032 } 5033 5034 // This code originates from JDK's sysOpen and open64_w 5035 // from src/solaris/hpi/src/system_md.c 5036 5037 #ifndef O_DELETE 5038 #define O_DELETE 0x10000 5039 #endif 5040 5041 // Open a file. Unlink the file immediately after open returns 5042 // if the specified oflag has the O_DELETE flag set. 5043 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c 5044 5045 int os::open(const char *path, int oflag, int mode) { 5046 5047 if (strlen(path) > MAX_PATH - 1) { 5048 errno = ENAMETOOLONG; 5049 return -1; 5050 } 5051 int fd; 5052 int o_delete = (oflag & O_DELETE); 5053 oflag = oflag & ~O_DELETE; 5054 5055 fd = ::open64(path, oflag, mode); 5056 if (fd == -1) return -1; 5057 5058 //If the open succeeded, the file might still be a directory 5059 { 5060 struct stat64 buf64; 5061 int ret = ::fstat64(fd, &buf64); 5062 int st_mode = buf64.st_mode; 5063 5064 if (ret != -1) { 5065 if ((st_mode & S_IFMT) == S_IFDIR) { 5066 errno = EISDIR; 5067 ::close(fd); 5068 return -1; 5069 } 5070 } else { 5071 ::close(fd); 5072 return -1; 5073 } 5074 } 5075 5076 /* 5077 * All file descriptors that are opened in the JVM and not 5078 * specifically destined for a subprocess should have the 5079 * close-on-exec flag set. If we don't set it, then careless 3rd 5080 * party native code might fork and exec without closing all 5081 * appropriate file descriptors (e.g. as we do in closeDescriptors in 5082 * UNIXProcess.c), and this in turn might: 5083 * 5084 * - cause end-of-file to fail to be detected on some file 5085 * descriptors, resulting in mysterious hangs, or 5086 * 5087 * - might cause an fopen in the subprocess to fail on a system 5088 * suffering from bug 1085341. 5089 * 5090 * (Yes, the default setting of the close-on-exec flag is a Unix 5091 * design flaw) 5092 * 5093 * See: 5094 * 1085341: 32-bit stdio routines should support file descriptors >255 5095 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5096 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5097 */ 5098 #ifdef FD_CLOEXEC 5099 { 5100 int flags = ::fcntl(fd, F_GETFD); 5101 if (flags != -1) 5102 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5103 } 5104 #endif 5105 5106 if (o_delete != 0) { 5107 ::unlink(path); 5108 } 5109 return fd; 5110 } 5111 5112 5113 // create binary file, rewriting existing file if required 5114 int os::create_binary_file(const char* path, bool rewrite_existing) { 5115 int oflags = O_WRONLY | O_CREAT; 5116 if (!rewrite_existing) { 5117 oflags |= O_EXCL; 5118 } 5119 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5120 } 5121 5122 // return current position of file pointer 5123 jlong os::current_file_offset(int fd) { 5124 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5125 } 5126 5127 // move file pointer to the specified offset 5128 jlong os::seek_to_file_offset(int fd, jlong offset) { 5129 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5130 } 5131 5132 // This code originates from JDK's sysAvailable 5133 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5134 5135 int os::available(int fd, jlong *bytes) { 5136 jlong cur, end; 5137 int mode; 5138 struct stat64 buf64; 5139 5140 if (::fstat64(fd, &buf64) >= 0) { 5141 mode = buf64.st_mode; 5142 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5143 /* 5144 * XXX: is the following call interruptible? If so, this might 5145 * need to go through the INTERRUPT_IO() wrapper as for other 5146 * blocking, interruptible calls in this file. 5147 */ 5148 int n; 5149 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5150 *bytes = n; 5151 return 1; 5152 } 5153 } 5154 } 5155 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5156 return 0; 5157 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5158 return 0; 5159 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5160 return 0; 5161 } 5162 *bytes = end - cur; 5163 return 1; 5164 } 5165 5166 int os::socket_available(int fd, jint *pbytes) { 5167 // Linux doc says EINTR not returned, unlike Solaris 5168 int ret = ::ioctl(fd, FIONREAD, pbytes); 5169 5170 //%% note ioctl can return 0 when successful, JVM_SocketAvailable 5171 // is expected to return 0 on failure and 1 on success to the jdk. 5172 return (ret < 0) ? 0 : 1; 5173 } 5174 5175 // Map a block of memory. 5176 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5177 char *addr, size_t bytes, bool read_only, 5178 bool allow_exec) { 5179 int prot; 5180 int flags = MAP_PRIVATE; 5181 5182 if (read_only) { 5183 prot = PROT_READ; 5184 } else { 5185 prot = PROT_READ | PROT_WRITE; 5186 } 5187 5188 if (allow_exec) { 5189 prot |= PROT_EXEC; 5190 } 5191 5192 if (addr != NULL) { 5193 flags |= MAP_FIXED; 5194 } 5195 5196 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5197 fd, file_offset); 5198 if (mapped_address == MAP_FAILED) { 5199 return NULL; 5200 } 5201 return mapped_address; 5202 } 5203 5204 5205 // Remap a block of memory. 5206 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5207 char *addr, size_t bytes, bool read_only, 5208 bool allow_exec) { 5209 // same as map_memory() on this OS 5210 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5211 allow_exec); 5212 } 5213 5214 5215 // Unmap a block of memory. 5216 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5217 return munmap(addr, bytes) == 0; 5218 } 5219 5220 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5221 5222 static clockid_t thread_cpu_clockid(Thread* thread) { 5223 pthread_t tid = thread->osthread()->pthread_id(); 5224 clockid_t clockid; 5225 5226 // Get thread clockid 5227 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5228 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5229 return clockid; 5230 } 5231 5232 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5233 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5234 // of a thread. 5235 // 5236 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5237 // the fast estimate available on the platform. 5238 5239 jlong os::current_thread_cpu_time() { 5240 if (os::Linux::supports_fast_thread_cpu_time()) { 5241 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5242 } else { 5243 // return user + sys since the cost is the same 5244 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5245 } 5246 } 5247 5248 jlong os::thread_cpu_time(Thread* thread) { 5249 // consistent with what current_thread_cpu_time() returns 5250 if (os::Linux::supports_fast_thread_cpu_time()) { 5251 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5252 } else { 5253 return slow_thread_cpu_time(thread, true /* user + sys */); 5254 } 5255 } 5256 5257 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5258 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5259 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5260 } else { 5261 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5262 } 5263 } 5264 5265 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5266 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5267 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5268 } else { 5269 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5270 } 5271 } 5272 5273 // 5274 // -1 on error. 5275 // 5276 5277 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5278 pid_t tid = thread->osthread()->thread_id(); 5279 char *s; 5280 char stat[2048]; 5281 int statlen; 5282 char proc_name[64]; 5283 int count; 5284 long sys_time, user_time; 5285 char cdummy; 5286 int idummy; 5287 long ldummy; 5288 FILE *fp; 5289 5290 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid); 5291 fp = fopen(proc_name, "r"); 5292 if (fp == NULL) return -1; 5293 statlen = fread(stat, 1, 2047, fp); 5294 stat[statlen] = '\0'; 5295 fclose(fp); 5296 5297 // Skip pid and the command string. Note that we could be dealing with 5298 // weird command names, e.g. user could decide to rename java launcher 5299 // to "java 1.4.2 :)", then the stat file would look like 5300 // 1234 (java 1.4.2 :)) R ... ... 5301 // We don't really need to know the command string, just find the last 5302 // occurrence of ")" and then start parsing from there. See bug 4726580. 5303 s = strrchr(stat, ')'); 5304 if (s == NULL) return -1; 5305 5306 // Skip blank chars 5307 do s++; while (isspace(*s)); 5308 5309 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5310 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5311 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5312 &user_time, &sys_time); 5313 if (count != 13) return -1; 5314 if (user_sys_cpu_time) { 5315 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5316 } else { 5317 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5318 } 5319 } 5320 5321 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5322 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5323 info_ptr->may_skip_backward = false; // elapsed time not wall time 5324 info_ptr->may_skip_forward = false; // elapsed time not wall time 5325 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5326 } 5327 5328 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5329 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5330 info_ptr->may_skip_backward = false; // elapsed time not wall time 5331 info_ptr->may_skip_forward = false; // elapsed time not wall time 5332 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5333 } 5334 5335 bool os::is_thread_cpu_time_supported() { 5336 return true; 5337 } 5338 5339 // System loadavg support. Returns -1 if load average cannot be obtained. 5340 // Linux doesn't yet have a (official) notion of processor sets, 5341 // so just return the system wide load average. 5342 int os::loadavg(double loadavg[], int nelem) { 5343 return ::getloadavg(loadavg, nelem); 5344 } 5345 5346 void os::pause() { 5347 char filename[MAX_PATH]; 5348 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5349 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5350 } else { 5351 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5352 } 5353 5354 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5355 if (fd != -1) { 5356 struct stat buf; 5357 ::close(fd); 5358 while (::stat(filename, &buf) == 0) { 5359 (void)::poll(NULL, 0, 100); 5360 } 5361 } else { 5362 jio_fprintf(stderr, 5363 "Could not open pause file '%s', continuing immediately.\n", filename); 5364 } 5365 } 5366 5367 5368 // Refer to the comments in os_solaris.cpp park-unpark. 5369 // 5370 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5371 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5372 // For specifics regarding the bug see GLIBC BUGID 261237 : 5373 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5374 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5375 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5376 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5377 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5378 // and monitorenter when we're using 1-0 locking. All those operations may result in 5379 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5380 // of libpthread avoids the problem, but isn't practical. 5381 // 5382 // Possible remedies: 5383 // 5384 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5385 // This is palliative and probabilistic, however. If the thread is preempted 5386 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5387 // than the minimum period may have passed, and the abstime may be stale (in the 5388 // past) resultin in a hang. Using this technique reduces the odds of a hang 5389 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5390 // 5391 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5392 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5393 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5394 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5395 // thread. 5396 // 5397 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5398 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5399 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5400 // This also works well. In fact it avoids kernel-level scalability impediments 5401 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5402 // timers in a graceful fashion. 5403 // 5404 // 4. When the abstime value is in the past it appears that control returns 5405 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5406 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5407 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5408 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5409 // It may be possible to avoid reinitialization by checking the return 5410 // value from pthread_cond_timedwait(). In addition to reinitializing the 5411 // condvar we must establish the invariant that cond_signal() is only called 5412 // within critical sections protected by the adjunct mutex. This prevents 5413 // cond_signal() from "seeing" a condvar that's in the midst of being 5414 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5415 // desirable signal-after-unlock optimization that avoids futile context switching. 5416 // 5417 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5418 // structure when a condvar is used or initialized. cond_destroy() would 5419 // release the helper structure. Our reinitialize-after-timedwait fix 5420 // put excessive stress on malloc/free and locks protecting the c-heap. 5421 // 5422 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5423 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5424 // and only enabling the work-around for vulnerable environments. 5425 5426 // utility to compute the abstime argument to timedwait: 5427 // millis is the relative timeout time 5428 // abstime will be the absolute timeout time 5429 // TODO: replace compute_abstime() with unpackTime() 5430 5431 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5432 if (millis < 0) millis = 0; 5433 5434 jlong seconds = millis / 1000; 5435 millis %= 1000; 5436 if (seconds > 50000000) { // see man cond_timedwait(3T) 5437 seconds = 50000000; 5438 } 5439 5440 if (os::supports_monotonic_clock()) { 5441 struct timespec now; 5442 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5443 assert_status(status == 0, status, "clock_gettime"); 5444 abstime->tv_sec = now.tv_sec + seconds; 5445 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5446 if (nanos >= NANOSECS_PER_SEC) { 5447 abstime->tv_sec += 1; 5448 nanos -= NANOSECS_PER_SEC; 5449 } 5450 abstime->tv_nsec = nanos; 5451 } else { 5452 struct timeval now; 5453 int status = gettimeofday(&now, NULL); 5454 assert(status == 0, "gettimeofday"); 5455 abstime->tv_sec = now.tv_sec + seconds; 5456 long usec = now.tv_usec + millis * 1000; 5457 if (usec >= 1000000) { 5458 abstime->tv_sec += 1; 5459 usec -= 1000000; 5460 } 5461 abstime->tv_nsec = usec * 1000; 5462 } 5463 return abstime; 5464 } 5465 5466 5467 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 5468 // Conceptually TryPark() should be equivalent to park(0). 5469 5470 int os::PlatformEvent::TryPark() { 5471 for (;;) { 5472 const int v = _Event; 5473 guarantee((v == 0) || (v == 1), "invariant"); 5474 if (Atomic::cmpxchg(0, &_Event, v) == v) return v; 5475 } 5476 } 5477 5478 void os::PlatformEvent::park() { // AKA "down()" 5479 // Invariant: Only the thread associated with the Event/PlatformEvent 5480 // may call park(). 5481 // TODO: assert that _Assoc != NULL or _Assoc == Self 5482 int v; 5483 for (;;) { 5484 v = _Event; 5485 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5486 } 5487 guarantee(v >= 0, "invariant"); 5488 if (v == 0) { 5489 // Do this the hard way by blocking ... 5490 int status = pthread_mutex_lock(_mutex); 5491 assert_status(status == 0, status, "mutex_lock"); 5492 guarantee(_nParked == 0, "invariant"); 5493 ++_nParked; 5494 while (_Event < 0) { 5495 status = pthread_cond_wait(_cond, _mutex); 5496 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5497 // Treat this the same as if the wait was interrupted 5498 if (status == ETIME) { status = EINTR; } 5499 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5500 } 5501 --_nParked; 5502 5503 _Event = 0; 5504 status = pthread_mutex_unlock(_mutex); 5505 assert_status(status == 0, status, "mutex_unlock"); 5506 // Paranoia to ensure our locked and lock-free paths interact 5507 // correctly with each other. 5508 OrderAccess::fence(); 5509 } 5510 guarantee(_Event >= 0, "invariant"); 5511 } 5512 5513 int os::PlatformEvent::park(jlong millis) { 5514 guarantee(_nParked == 0, "invariant"); 5515 5516 int v; 5517 for (;;) { 5518 v = _Event; 5519 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5520 } 5521 guarantee(v >= 0, "invariant"); 5522 if (v != 0) return OS_OK; 5523 5524 // We do this the hard way, by blocking the thread. 5525 // Consider enforcing a minimum timeout value. 5526 struct timespec abst; 5527 compute_abstime(&abst, millis); 5528 5529 int ret = OS_TIMEOUT; 5530 int status = pthread_mutex_lock(_mutex); 5531 assert_status(status == 0, status, "mutex_lock"); 5532 guarantee(_nParked == 0, "invariant"); 5533 ++_nParked; 5534 5535 // Object.wait(timo) will return because of 5536 // (a) notification 5537 // (b) timeout 5538 // (c) thread.interrupt 5539 // 5540 // Thread.interrupt and object.notify{All} both call Event::set. 5541 // That is, we treat thread.interrupt as a special case of notification. 5542 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false. 5543 // We assume all ETIME returns are valid. 5544 // 5545 // TODO: properly differentiate simultaneous notify+interrupt. 5546 // In that case, we should propagate the notify to another waiter. 5547 5548 while (_Event < 0) { 5549 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5550 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5551 pthread_cond_destroy(_cond); 5552 pthread_cond_init(_cond, os::Linux::condAttr()); 5553 } 5554 assert_status(status == 0 || status == EINTR || 5555 status == ETIME || status == ETIMEDOUT, 5556 status, "cond_timedwait"); 5557 if (!FilterSpuriousWakeups) break; // previous semantics 5558 if (status == ETIME || status == ETIMEDOUT) break; 5559 // We consume and ignore EINTR and spurious wakeups. 5560 } 5561 --_nParked; 5562 if (_Event >= 0) { 5563 ret = OS_OK; 5564 } 5565 _Event = 0; 5566 status = pthread_mutex_unlock(_mutex); 5567 assert_status(status == 0, status, "mutex_unlock"); 5568 assert(_nParked == 0, "invariant"); 5569 // Paranoia to ensure our locked and lock-free paths interact 5570 // correctly with each other. 5571 OrderAccess::fence(); 5572 return ret; 5573 } 5574 5575 void os::PlatformEvent::unpark() { 5576 // Transitions for _Event: 5577 // 0 :=> 1 5578 // 1 :=> 1 5579 // -1 :=> either 0 or 1; must signal target thread 5580 // That is, we can safely transition _Event from -1 to either 5581 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back 5582 // unpark() calls. 5583 // See also: "Semaphores in Plan 9" by Mullender & Cox 5584 // 5585 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5586 // that it will take two back-to-back park() calls for the owning 5587 // thread to block. This has the benefit of forcing a spurious return 5588 // from the first park() call after an unpark() call which will help 5589 // shake out uses of park() and unpark() without condition variables. 5590 5591 if (Atomic::xchg(1, &_Event) >= 0) return; 5592 5593 // Wait for the thread associated with the event to vacate 5594 int status = pthread_mutex_lock(_mutex); 5595 assert_status(status == 0, status, "mutex_lock"); 5596 int AnyWaiters = _nParked; 5597 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5598 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5599 AnyWaiters = 0; 5600 pthread_cond_signal(_cond); 5601 } 5602 status = pthread_mutex_unlock(_mutex); 5603 assert_status(status == 0, status, "mutex_unlock"); 5604 if (AnyWaiters != 0) { 5605 status = pthread_cond_signal(_cond); 5606 assert_status(status == 0, status, "cond_signal"); 5607 } 5608 5609 // Note that we signal() _after dropping the lock for "immortal" Events. 5610 // This is safe and avoids a common class of futile wakeups. In rare 5611 // circumstances this can cause a thread to return prematurely from 5612 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 5613 // simply re-test the condition and re-park itself. 5614 } 5615 5616 5617 // JSR166 5618 // ------------------------------------------------------- 5619 5620 /* 5621 * The solaris and linux implementations of park/unpark are fairly 5622 * conservative for now, but can be improved. They currently use a 5623 * mutex/condvar pair, plus a a count. 5624 * Park decrements count if > 0, else does a condvar wait. Unpark 5625 * sets count to 1 and signals condvar. Only one thread ever waits 5626 * on the condvar. Contention seen when trying to park implies that someone 5627 * is unparking you, so don't wait. And spurious returns are fine, so there 5628 * is no need to track notifications. 5629 */ 5630 5631 /* 5632 * This code is common to linux and solaris and will be moved to a 5633 * common place in dolphin. 5634 * 5635 * The passed in time value is either a relative time in nanoseconds 5636 * or an absolute time in milliseconds. Either way it has to be unpacked 5637 * into suitable seconds and nanoseconds components and stored in the 5638 * given timespec structure. 5639 * Given time is a 64-bit value and the time_t used in the timespec is only 5640 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 5641 * overflow if times way in the future are given. Further on Solaris versions 5642 * prior to 10 there is a restriction (see cond_timedwait) that the specified 5643 * number of seconds, in abstime, is less than current_time + 100,000,000. 5644 * As it will be 28 years before "now + 100000000" will overflow we can 5645 * ignore overflow and just impose a hard-limit on seconds using the value 5646 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 5647 * years from "now". 5648 */ 5649 5650 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5651 assert(time > 0, "convertTime"); 5652 time_t max_secs = 0; 5653 5654 if (!os::supports_monotonic_clock() || isAbsolute) { 5655 struct timeval now; 5656 int status = gettimeofday(&now, NULL); 5657 assert(status == 0, "gettimeofday"); 5658 5659 max_secs = now.tv_sec + MAX_SECS; 5660 5661 if (isAbsolute) { 5662 jlong secs = time / 1000; 5663 if (secs > max_secs) { 5664 absTime->tv_sec = max_secs; 5665 } else { 5666 absTime->tv_sec = secs; 5667 } 5668 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5669 } else { 5670 jlong secs = time / NANOSECS_PER_SEC; 5671 if (secs >= MAX_SECS) { 5672 absTime->tv_sec = max_secs; 5673 absTime->tv_nsec = 0; 5674 } else { 5675 absTime->tv_sec = now.tv_sec + secs; 5676 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5677 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5678 absTime->tv_nsec -= NANOSECS_PER_SEC; 5679 ++absTime->tv_sec; // note: this must be <= max_secs 5680 } 5681 } 5682 } 5683 } else { 5684 // must be relative using monotonic clock 5685 struct timespec now; 5686 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5687 assert_status(status == 0, status, "clock_gettime"); 5688 max_secs = now.tv_sec + MAX_SECS; 5689 jlong secs = time / NANOSECS_PER_SEC; 5690 if (secs >= MAX_SECS) { 5691 absTime->tv_sec = max_secs; 5692 absTime->tv_nsec = 0; 5693 } else { 5694 absTime->tv_sec = now.tv_sec + secs; 5695 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5696 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5697 absTime->tv_nsec -= NANOSECS_PER_SEC; 5698 ++absTime->tv_sec; // note: this must be <= max_secs 5699 } 5700 } 5701 } 5702 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5703 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5704 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5705 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5706 } 5707 5708 void Parker::park(bool isAbsolute, jlong time) { 5709 // Ideally we'd do something useful while spinning, such 5710 // as calling unpackTime(). 5711 5712 // Optional fast-path check: 5713 // Return immediately if a permit is available. 5714 // We depend on Atomic::xchg() having full barrier semantics 5715 // since we are doing a lock-free update to _counter. 5716 if (Atomic::xchg(0, &_counter) > 0) return; 5717 5718 Thread* thread = Thread::current(); 5719 assert(thread->is_Java_thread(), "Must be JavaThread"); 5720 JavaThread *jt = (JavaThread *)thread; 5721 5722 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5723 // Check interrupt before trying to wait 5724 if (Thread::is_interrupted(thread, false)) { 5725 return; 5726 } 5727 5728 // Next, demultiplex/decode time arguments 5729 timespec absTime; 5730 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all 5731 return; 5732 } 5733 if (time > 0) { 5734 unpackTime(&absTime, isAbsolute, time); 5735 } 5736 5737 5738 // Enter safepoint region 5739 // Beware of deadlocks such as 6317397. 5740 // The per-thread Parker:: mutex is a classic leaf-lock. 5741 // In particular a thread must never block on the Threads_lock while 5742 // holding the Parker:: mutex. If safepoints are pending both the 5743 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5744 ThreadBlockInVM tbivm(jt); 5745 5746 // Don't wait if cannot get lock since interference arises from 5747 // unblocking. Also. check interrupt before trying wait 5748 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5749 return; 5750 } 5751 5752 int status; 5753 if (_counter > 0) { // no wait needed 5754 _counter = 0; 5755 status = pthread_mutex_unlock(_mutex); 5756 assert(status == 0, "invariant"); 5757 // Paranoia to ensure our locked and lock-free paths interact 5758 // correctly with each other and Java-level accesses. 5759 OrderAccess::fence(); 5760 return; 5761 } 5762 5763 #ifdef ASSERT 5764 // Don't catch signals while blocked; let the running threads have the signals. 5765 // (This allows a debugger to break into the running thread.) 5766 sigset_t oldsigs; 5767 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5768 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5769 #endif 5770 5771 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5772 jt->set_suspend_equivalent(); 5773 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5774 5775 assert(_cur_index == -1, "invariant"); 5776 if (time == 0) { 5777 _cur_index = REL_INDEX; // arbitrary choice when not timed 5778 status = pthread_cond_wait(&_cond[_cur_index], _mutex); 5779 } else { 5780 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5781 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime); 5782 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5783 pthread_cond_destroy(&_cond[_cur_index]); 5784 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5785 } 5786 } 5787 _cur_index = -1; 5788 assert_status(status == 0 || status == EINTR || 5789 status == ETIME || status == ETIMEDOUT, 5790 status, "cond_timedwait"); 5791 5792 #ifdef ASSERT 5793 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5794 #endif 5795 5796 _counter = 0; 5797 status = pthread_mutex_unlock(_mutex); 5798 assert_status(status == 0, status, "invariant"); 5799 // Paranoia to ensure our locked and lock-free paths interact 5800 // correctly with each other and Java-level accesses. 5801 OrderAccess::fence(); 5802 5803 // If externally suspended while waiting, re-suspend 5804 if (jt->handle_special_suspend_equivalent_condition()) { 5805 jt->java_suspend_self(); 5806 } 5807 } 5808 5809 void Parker::unpark() { 5810 int s, status; 5811 status = pthread_mutex_lock(_mutex); 5812 assert(status == 0, "invariant"); 5813 s = _counter; 5814 _counter = 1; 5815 if (s < 1) { 5816 // thread might be parked 5817 if (_cur_index != -1) { 5818 // thread is definitely parked 5819 if (WorkAroundNPTLTimedWaitHang) { 5820 status = pthread_cond_signal (&_cond[_cur_index]); 5821 assert(status == 0, "invariant"); 5822 status = pthread_mutex_unlock(_mutex); 5823 assert(status == 0, "invariant"); 5824 } else { 5825 status = pthread_mutex_unlock(_mutex); 5826 assert(status == 0, "invariant"); 5827 status = pthread_cond_signal (&_cond[_cur_index]); 5828 assert(status == 0, "invariant"); 5829 } 5830 } else { 5831 pthread_mutex_unlock(_mutex); 5832 assert(status == 0, "invariant"); 5833 } 5834 } else { 5835 pthread_mutex_unlock(_mutex); 5836 assert(status == 0, "invariant"); 5837 } 5838 } 5839 5840 5841 extern char** environ; 5842 5843 #ifndef __NR_fork 5844 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5845 #endif 5846 5847 #ifndef __NR_execve 5848 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 5849 #endif 5850 5851 // Run the specified command in a separate process. Return its exit value, 5852 // or -1 on failure (e.g. can't fork a new process). 5853 // Unlike system(), this function can be called from signal handler. It 5854 // doesn't block SIGINT et al. 5855 int os::fork_and_exec(char* cmd) { 5856 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5857 5858 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5859 // pthread_atfork handlers and reset pthread library. All we need is a 5860 // separate process to execve. Make a direct syscall to fork process. 5861 // On IA64 there's no fork syscall, we have to use fork() and hope for 5862 // the best... 5863 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5864 IA64_ONLY(fork();) 5865 5866 if (pid < 0) { 5867 // fork failed 5868 return -1; 5869 5870 } else if (pid == 0) { 5871 // child process 5872 5873 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5874 // first to kill every thread on the thread list. Because this list is 5875 // not reset by fork() (see notes above), execve() will instead kill 5876 // every thread in the parent process. We know this is the only thread 5877 // in the new process, so make a system call directly. 5878 // IA64 should use normal execve() from glibc to match the glibc fork() 5879 // above. 5880 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5881 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5882 5883 // execve failed 5884 _exit(-1); 5885 5886 } else { 5887 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5888 // care about the actual exit code, for now. 5889 5890 int status; 5891 5892 // Wait for the child process to exit. This returns immediately if 5893 // the child has already exited. */ 5894 while (waitpid(pid, &status, 0) < 0) { 5895 switch (errno) { 5896 case ECHILD: return 0; 5897 case EINTR: break; 5898 default: return -1; 5899 } 5900 } 5901 5902 if (WIFEXITED(status)) { 5903 // The child exited normally; get its exit code. 5904 return WEXITSTATUS(status); 5905 } else if (WIFSIGNALED(status)) { 5906 // The child exited because of a signal 5907 // The best value to return is 0x80 + signal number, 5908 // because that is what all Unix shells do, and because 5909 // it allows callers to distinguish between process exit and 5910 // process death by signal. 5911 return 0x80 + WTERMSIG(status); 5912 } else { 5913 // Unknown exit code; pass it through 5914 return status; 5915 } 5916 } 5917 } 5918 5919 // is_headless_jre() 5920 // 5921 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 5922 // in order to report if we are running in a headless jre 5923 // 5924 // Since JDK8 xawt/libmawt.so was moved into the same directory 5925 // as libawt.so, and renamed libawt_xawt.so 5926 // 5927 bool os::is_headless_jre() { 5928 struct stat statbuf; 5929 char buf[MAXPATHLEN]; 5930 char libmawtpath[MAXPATHLEN]; 5931 const char *xawtstr = "/xawt/libmawt.so"; 5932 const char *new_xawtstr = "/libawt_xawt.so"; 5933 char *p; 5934 5935 // Get path to libjvm.so 5936 os::jvm_path(buf, sizeof(buf)); 5937 5938 // Get rid of libjvm.so 5939 p = strrchr(buf, '/'); 5940 if (p == NULL) return false; 5941 else *p = '\0'; 5942 5943 // Get rid of client or server 5944 p = strrchr(buf, '/'); 5945 if (p == NULL) return false; 5946 else *p = '\0'; 5947 5948 // check xawt/libmawt.so 5949 strcpy(libmawtpath, buf); 5950 strcat(libmawtpath, xawtstr); 5951 if (::stat(libmawtpath, &statbuf) == 0) return false; 5952 5953 // check libawt_xawt.so 5954 strcpy(libmawtpath, buf); 5955 strcat(libmawtpath, new_xawtstr); 5956 if (::stat(libmawtpath, &statbuf) == 0) return false; 5957 5958 return true; 5959 } 5960 5961 // Get the default path to the core file 5962 // Returns the length of the string 5963 int os::get_core_path(char* buffer, size_t bufferSize) { 5964 const char* p = get_current_directory(buffer, bufferSize); 5965 5966 if (p == NULL) { 5967 assert(p != NULL, "failed to get current directory"); 5968 return 0; 5969 } 5970 5971 return strlen(buffer); 5972 } 5973 5974 #ifdef JAVASE_EMBEDDED 5975 // 5976 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory. 5977 // 5978 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL; 5979 5980 // ctor 5981 // 5982 MemNotifyThread::MemNotifyThread(int fd): Thread() { 5983 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread"); 5984 _fd = fd; 5985 5986 if (os::create_thread(this, os::os_thread)) { 5987 _memnotify_thread = this; 5988 os::set_priority(this, NearMaxPriority); 5989 os::start_thread(this); 5990 } 5991 } 5992 5993 // Where all the work gets done 5994 // 5995 void MemNotifyThread::run() { 5996 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread"); 5997 5998 // Set up the select arguments 5999 fd_set rfds; 6000 if (_fd != -1) { 6001 FD_ZERO(&rfds); 6002 FD_SET(_fd, &rfds); 6003 } 6004 6005 // Now wait for the mem_notify device to wake up 6006 while (1) { 6007 // Wait for the mem_notify device to signal us.. 6008 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL); 6009 if (rc == -1) { 6010 perror("select!\n"); 6011 break; 6012 } else if (rc) { 6013 //ssize_t free_before = os::available_memory(); 6014 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024); 6015 6016 // The kernel is telling us there is not much memory left... 6017 // try to do something about that 6018 6019 // If we are not already in a GC, try one. 6020 if (!Universe::heap()->is_gc_active()) { 6021 Universe::heap()->collect(GCCause::_allocation_failure); 6022 6023 //ssize_t free_after = os::available_memory(); 6024 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024); 6025 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024); 6026 } 6027 // We might want to do something like the following if we find the GC's are not helping... 6028 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true); 6029 } 6030 } 6031 } 6032 6033 // 6034 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it. 6035 // 6036 void MemNotifyThread::start() { 6037 int fd; 6038 fd = open ("/dev/mem_notify", O_RDONLY, 0); 6039 if (fd < 0) { 6040 return; 6041 } 6042 6043 if (memnotify_thread() == NULL) { 6044 new MemNotifyThread(fd); 6045 } 6046 } 6047 6048 #endif // JAVASE_EMBEDDED 6049 6050 6051 /////////////// Unit tests /////////////// 6052 6053 #ifndef PRODUCT 6054 6055 #define test_log(...) \ 6056 do {\ 6057 if (VerboseInternalVMTests) { \ 6058 tty->print_cr(__VA_ARGS__); \ 6059 tty->flush(); \ 6060 }\ 6061 } while (false) 6062 6063 class TestReserveMemorySpecial : AllStatic { 6064 public: 6065 static void small_page_write(void* addr, size_t size) { 6066 size_t page_size = os::vm_page_size(); 6067 6068 char* end = (char*)addr + size; 6069 for (char* p = (char*)addr; p < end; p += page_size) { 6070 *p = 1; 6071 } 6072 } 6073 6074 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6075 if (!UseHugeTLBFS) { 6076 return; 6077 } 6078 6079 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6080 6081 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6082 6083 if (addr != NULL) { 6084 small_page_write(addr, size); 6085 6086 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6087 } 6088 } 6089 6090 static void test_reserve_memory_special_huge_tlbfs_only() { 6091 if (!UseHugeTLBFS) { 6092 return; 6093 } 6094 6095 size_t lp = os::large_page_size(); 6096 6097 for (size_t size = lp; size <= lp * 10; size += lp) { 6098 test_reserve_memory_special_huge_tlbfs_only(size); 6099 } 6100 } 6101 6102 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) { 6103 if (!UseHugeTLBFS) { 6104 return; 6105 } 6106 6107 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")", 6108 size, alignment); 6109 6110 assert(size >= os::large_page_size(), "Incorrect input to test"); 6111 6112 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6113 6114 if (addr != NULL) { 6115 small_page_write(addr, size); 6116 6117 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6118 } 6119 } 6120 6121 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) { 6122 size_t lp = os::large_page_size(); 6123 size_t ag = os::vm_allocation_granularity(); 6124 6125 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6126 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment); 6127 } 6128 } 6129 6130 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6131 size_t lp = os::large_page_size(); 6132 size_t ag = os::vm_allocation_granularity(); 6133 6134 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp); 6135 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag); 6136 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2); 6137 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2); 6138 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag); 6139 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag); 6140 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2); 6141 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10); 6142 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2); 6143 } 6144 6145 static void test_reserve_memory_special_huge_tlbfs() { 6146 if (!UseHugeTLBFS) { 6147 return; 6148 } 6149 6150 test_reserve_memory_special_huge_tlbfs_only(); 6151 test_reserve_memory_special_huge_tlbfs_mixed(); 6152 } 6153 6154 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6155 if (!UseSHM) { 6156 return; 6157 } 6158 6159 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6160 6161 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6162 6163 if (addr != NULL) { 6164 assert(is_ptr_aligned(addr, alignment), "Check"); 6165 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6166 6167 small_page_write(addr, size); 6168 6169 os::Linux::release_memory_special_shm(addr, size); 6170 } 6171 } 6172 6173 static void test_reserve_memory_special_shm() { 6174 size_t lp = os::large_page_size(); 6175 size_t ag = os::vm_allocation_granularity(); 6176 6177 for (size_t size = ag; size < lp * 3; size += ag) { 6178 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6179 test_reserve_memory_special_shm(size, alignment); 6180 } 6181 } 6182 } 6183 6184 static void test() { 6185 test_reserve_memory_special_huge_tlbfs(); 6186 test_reserve_memory_special_shm(); 6187 } 6188 }; 6189 6190 void TestReserveMemorySpecial_test() { 6191 TestReserveMemorySpecial::test(); 6192 } 6193 6194 #endif