1 /* 2 * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 // no precompiled headers 26 #include "classfile/classLoader.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "code/icBuffer.hpp" 30 #include "code/vtableStubs.hpp" 31 #include "compiler/compileBroker.hpp" 32 #include "compiler/disassembler.hpp" 33 #include "interpreter/interpreter.hpp" 34 #include "jvm_linux.h" 35 #include "memory/allocation.inline.hpp" 36 #include "memory/filemap.hpp" 37 #include "mutex_linux.inline.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "os_share_linux.hpp" 40 #include "prims/jniFastGetField.hpp" 41 #include "prims/jvm.h" 42 #include "prims/jvm_misc.hpp" 43 #include "runtime/arguments.hpp" 44 #include "runtime/extendedPC.hpp" 45 #include "runtime/globals.hpp" 46 #include "runtime/interfaceSupport.hpp" 47 #include "runtime/init.hpp" 48 #include "runtime/java.hpp" 49 #include "runtime/javaCalls.hpp" 50 #include "runtime/mutexLocker.hpp" 51 #include "runtime/objectMonitor.hpp" 52 #include "runtime/orderAccess.inline.hpp" 53 #include "runtime/osThread.hpp" 54 #include "runtime/perfMemory.hpp" 55 #include "runtime/sharedRuntime.hpp" 56 #include "runtime/statSampler.hpp" 57 #include "runtime/stubRoutines.hpp" 58 #include "runtime/thread.inline.hpp" 59 #include "runtime/threadCritical.hpp" 60 #include "runtime/timer.hpp" 61 #include "services/attachListener.hpp" 62 #include "services/memTracker.hpp" 63 #include "services/runtimeService.hpp" 64 #include "utilities/decoder.hpp" 65 #include "utilities/defaultStream.hpp" 66 #include "utilities/events.hpp" 67 #include "utilities/elfFile.hpp" 68 #include "utilities/growableArray.hpp" 69 #include "utilities/vmError.hpp" 70 71 // put OS-includes here 72 # include <sys/types.h> 73 # include <sys/mman.h> 74 # include <sys/stat.h> 75 # include <sys/select.h> 76 # include <pthread.h> 77 # include <signal.h> 78 # include <errno.h> 79 # include <dlfcn.h> 80 # include <stdio.h> 81 # include <unistd.h> 82 # include <sys/resource.h> 83 # include <pthread.h> 84 # include <sys/stat.h> 85 # include <sys/time.h> 86 # include <sys/times.h> 87 # include <sys/utsname.h> 88 # include <sys/socket.h> 89 # include <sys/wait.h> 90 # include <pwd.h> 91 # include <poll.h> 92 # include <semaphore.h> 93 # include <fcntl.h> 94 # include <string.h> 95 # include <syscall.h> 96 # include <sys/sysinfo.h> 97 # include <gnu/libc-version.h> 98 # include <sys/ipc.h> 99 # include <sys/shm.h> 100 # include <link.h> 101 # include <stdint.h> 102 # include <inttypes.h> 103 # include <sys/ioctl.h> 104 105 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 106 107 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling 108 // getrusage() is prepared to handle the associated failure. 109 #ifndef RUSAGE_THREAD 110 #define RUSAGE_THREAD (1) /* only the calling thread */ 111 #endif 112 113 #define MAX_PATH (2 * K) 114 115 #define MAX_SECS 100000000 116 117 // for timer info max values which include all bits 118 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 119 120 #define LARGEPAGES_BIT (1 << 6) 121 //////////////////////////////////////////////////////////////////////////////// 122 // global variables 123 julong os::Linux::_physical_memory = 0; 124 125 address os::Linux::_initial_thread_stack_bottom = NULL; 126 uintptr_t os::Linux::_initial_thread_stack_size = 0; 127 128 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 129 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 130 Mutex* os::Linux::_createThread_lock = NULL; 131 pthread_t os::Linux::_main_thread; 132 int os::Linux::_page_size = -1; 133 const int os::Linux::_vm_default_page_size = (8 * K); 134 bool os::Linux::_is_floating_stack = false; 135 bool os::Linux::_is_NPTL = false; 136 bool os::Linux::_supports_fast_thread_cpu_time = false; 137 const char * os::Linux::_glibc_version = NULL; 138 const char * os::Linux::_libpthread_version = NULL; 139 pthread_condattr_t os::Linux::_condattr[1]; 140 141 static jlong initial_time_count=0; 142 143 static int clock_tics_per_sec = 100; 144 145 // For diagnostics to print a message once. see run_periodic_checks 146 static sigset_t check_signal_done; 147 static bool check_signals = true; 148 149 static pid_t _initial_pid = 0; 150 151 /* Signal number used to suspend/resume a thread */ 152 153 /* do not use any signal number less than SIGSEGV, see 4355769 */ 154 static int SR_signum = SIGUSR2; 155 sigset_t SR_sigset; 156 157 /* Used to protect dlsym() calls */ 158 static pthread_mutex_t dl_mutex; 159 160 // Declarations 161 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time); 162 163 #ifdef JAVASE_EMBEDDED 164 class MemNotifyThread: public Thread { 165 friend class VMStructs; 166 public: 167 virtual void run(); 168 169 private: 170 static MemNotifyThread* _memnotify_thread; 171 int _fd; 172 173 public: 174 175 // Constructor 176 MemNotifyThread(int fd); 177 178 // Tester 179 bool is_memnotify_thread() const { return true; } 180 181 // Printing 182 char* name() const { return (char*)"Linux MemNotify Thread"; } 183 184 // Returns the single instance of the MemNotifyThread 185 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; } 186 187 // Create and start the single instance of MemNotifyThread 188 static void start(); 189 }; 190 #endif // JAVASE_EMBEDDED 191 192 // utility functions 193 194 static int SR_initialize(); 195 196 julong os::available_memory() { 197 return Linux::available_memory(); 198 } 199 200 julong os::Linux::available_memory() { 201 // values in struct sysinfo are "unsigned long" 202 struct sysinfo si; 203 sysinfo(&si); 204 205 return (julong)si.freeram * si.mem_unit; 206 } 207 208 julong os::physical_memory() { 209 return Linux::physical_memory(); 210 } 211 212 //////////////////////////////////////////////////////////////////////////////// 213 // environment support 214 215 bool os::getenv(const char* name, char* buf, int len) { 216 const char* val = ::getenv(name); 217 if (val != NULL && strlen(val) < (size_t)len) { 218 strcpy(buf, val); 219 return true; 220 } 221 if (len > 0) buf[0] = 0; // return a null string 222 return false; 223 } 224 225 226 // Return true if user is running as root. 227 228 bool os::have_special_privileges() { 229 static bool init = false; 230 static bool privileges = false; 231 if (!init) { 232 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 233 init = true; 234 } 235 return privileges; 236 } 237 238 239 #ifndef SYS_gettid 240 // i386: 224, ia64: 1105, amd64: 186, sparc 143 241 #ifdef __ia64__ 242 #define SYS_gettid 1105 243 #elif __i386__ 244 #define SYS_gettid 224 245 #elif __amd64__ 246 #define SYS_gettid 186 247 #elif __sparc__ 248 #define SYS_gettid 143 249 #else 250 #error define gettid for the arch 251 #endif 252 #endif 253 254 // Cpu architecture string 255 #if defined(ZERO) 256 static char cpu_arch[] = ZERO_LIBARCH; 257 #elif defined(IA64) 258 static char cpu_arch[] = "ia64"; 259 #elif defined(IA32) 260 static char cpu_arch[] = "i386"; 261 #elif defined(AMD64) 262 static char cpu_arch[] = "amd64"; 263 #elif defined(ARM) 264 static char cpu_arch[] = "arm"; 265 #elif defined(PPC32) 266 static char cpu_arch[] = "ppc"; 267 #elif defined(PPC64) 268 static char cpu_arch[] = "ppc64"; 269 #elif defined(SPARC) 270 # ifdef _LP64 271 static char cpu_arch[] = "sparcv9"; 272 # else 273 static char cpu_arch[] = "sparc"; 274 # endif 275 #else 276 #error Add appropriate cpu_arch setting 277 #endif 278 279 280 // pid_t gettid() 281 // 282 // Returns the kernel thread id of the currently running thread. Kernel 283 // thread id is used to access /proc. 284 // 285 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 286 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 287 // 288 pid_t os::Linux::gettid() { 289 int rslt = syscall(SYS_gettid); 290 if (rslt == -1) { 291 // old kernel, no NPTL support 292 return getpid(); 293 } else { 294 return (pid_t)rslt; 295 } 296 } 297 298 // Most versions of linux have a bug where the number of processors are 299 // determined by looking at the /proc file system. In a chroot environment, 300 // the system call returns 1. This causes the VM to act as if it is 301 // a single processor and elide locking (see is_MP() call). 302 static bool unsafe_chroot_detected = false; 303 static const char *unstable_chroot_error = "/proc file system not found.\n" 304 "Java may be unstable running multithreaded in a chroot " 305 "environment on Linux when /proc filesystem is not mounted."; 306 307 void os::Linux::initialize_system_info() { 308 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 309 if (processor_count() == 1) { 310 pid_t pid = os::Linux::gettid(); 311 char fname[32]; 312 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 313 FILE *fp = fopen(fname, "r"); 314 if (fp == NULL) { 315 unsafe_chroot_detected = true; 316 } else { 317 fclose(fp); 318 } 319 } 320 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 321 assert(processor_count() > 0, "linux error"); 322 } 323 324 void os::init_system_properties_values() { 325 // The next steps are taken in the product version: 326 // 327 // Obtain the JAVA_HOME value from the location of libjvm.so. 328 // This library should be located at: 329 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 330 // 331 // If "/jre/lib/" appears at the right place in the path, then we 332 // assume libjvm.so is installed in a JDK and we use this path. 333 // 334 // Otherwise exit with message: "Could not create the Java virtual machine." 335 // 336 // The following extra steps are taken in the debugging version: 337 // 338 // If "/jre/lib/" does NOT appear at the right place in the path 339 // instead of exit check for $JAVA_HOME environment variable. 340 // 341 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 342 // then we append a fake suffix "hotspot/libjvm.so" to this path so 343 // it looks like libjvm.so is installed there 344 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 345 // 346 // Otherwise exit. 347 // 348 // Important note: if the location of libjvm.so changes this 349 // code needs to be changed accordingly. 350 351 // See ld(1): 352 // The linker uses the following search paths to locate required 353 // shared libraries: 354 // 1: ... 355 // ... 356 // 7: The default directories, normally /lib and /usr/lib. 357 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 358 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 359 #else 360 #define DEFAULT_LIBPATH "/lib:/usr/lib" 361 #endif 362 363 // Base path of extensions installed on the system. 364 #define SYS_EXT_DIR "/usr/java/packages" 365 #define EXTENSIONS_DIR "/lib/ext" 366 #define ENDORSED_DIR "/lib/endorsed" 367 368 // Buffer that fits several sprintfs. 369 // Note that the space for the colon and the trailing null are provided 370 // by the nulls included by the sizeof operator. 371 const size_t bufsize = 372 MAX3((size_t)MAXPATHLEN, // For dll_dir & friends. 373 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir 374 (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir 375 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 376 377 // sysclasspath, java_home, dll_dir 378 { 379 char *pslash; 380 os::jvm_path(buf, bufsize); 381 382 // Found the full path to libjvm.so. 383 // Now cut the path to <java_home>/jre if we can. 384 *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so. 385 pslash = strrchr(buf, '/'); 386 if (pslash != NULL) { 387 *pslash = '\0'; // Get rid of /{client|server|hotspot}. 388 } 389 Arguments::set_dll_dir(buf); 390 391 if (pslash != NULL) { 392 pslash = strrchr(buf, '/'); 393 if (pslash != NULL) { 394 *pslash = '\0'; // Get rid of /<arch>. 395 pslash = strrchr(buf, '/'); 396 if (pslash != NULL) { 397 *pslash = '\0'; // Get rid of /lib. 398 } 399 } 400 } 401 Arguments::set_java_home(buf); 402 set_boot_path('/', ':'); 403 } 404 405 // Where to look for native libraries. 406 // 407 // Note: Due to a legacy implementation, most of the library path 408 // is set in the launcher. This was to accomodate linking restrictions 409 // on legacy Linux implementations (which are no longer supported). 410 // Eventually, all the library path setting will be done here. 411 // 412 // However, to prevent the proliferation of improperly built native 413 // libraries, the new path component /usr/java/packages is added here. 414 // Eventually, all the library path setting will be done here. 415 { 416 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It 417 // should always exist (until the legacy problem cited above is 418 // addressed). 419 const char *v = ::getenv("LD_LIBRARY_PATH"); 420 const char *v_colon = ":"; 421 if (v == NULL) { v = ""; v_colon = ""; } 422 // That's +1 for the colon and +1 for the trailing '\0'. 423 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char, 424 strlen(v) + 1 + 425 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1, 426 mtInternal); 427 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch); 428 Arguments::set_library_path(ld_library_path); 429 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal); 430 } 431 432 // Extensions directories. 433 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home()); 434 Arguments::set_ext_dirs(buf); 435 436 // Endorsed standards default directory. 437 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 438 Arguments::set_endorsed_dirs(buf); 439 440 FREE_C_HEAP_ARRAY(char, buf, mtInternal); 441 442 #undef DEFAULT_LIBPATH 443 #undef SYS_EXT_DIR 444 #undef EXTENSIONS_DIR 445 #undef ENDORSED_DIR 446 } 447 448 //////////////////////////////////////////////////////////////////////////////// 449 // breakpoint support 450 451 void os::breakpoint() { 452 BREAKPOINT; 453 } 454 455 extern "C" void breakpoint() { 456 // use debugger to set breakpoint here 457 } 458 459 //////////////////////////////////////////////////////////////////////////////// 460 // signal support 461 462 debug_only(static bool signal_sets_initialized = false); 463 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 464 465 bool os::Linux::is_sig_ignored(int sig) { 466 struct sigaction oact; 467 sigaction(sig, (struct sigaction*)NULL, &oact); 468 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 469 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 470 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 471 return true; 472 else 473 return false; 474 } 475 476 void os::Linux::signal_sets_init() { 477 // Should also have an assertion stating we are still single-threaded. 478 assert(!signal_sets_initialized, "Already initialized"); 479 // Fill in signals that are necessarily unblocked for all threads in 480 // the VM. Currently, we unblock the following signals: 481 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 482 // by -Xrs (=ReduceSignalUsage)); 483 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 484 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 485 // the dispositions or masks wrt these signals. 486 // Programs embedding the VM that want to use the above signals for their 487 // own purposes must, at this time, use the "-Xrs" option to prevent 488 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 489 // (See bug 4345157, and other related bugs). 490 // In reality, though, unblocking these signals is really a nop, since 491 // these signals are not blocked by default. 492 sigemptyset(&unblocked_sigs); 493 sigemptyset(&allowdebug_blocked_sigs); 494 sigaddset(&unblocked_sigs, SIGILL); 495 sigaddset(&unblocked_sigs, SIGSEGV); 496 sigaddset(&unblocked_sigs, SIGBUS); 497 sigaddset(&unblocked_sigs, SIGFPE); 498 #if defined(PPC64) 499 sigaddset(&unblocked_sigs, SIGTRAP); 500 #endif 501 sigaddset(&unblocked_sigs, SR_signum); 502 503 if (!ReduceSignalUsage) { 504 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 505 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 506 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 507 } 508 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 509 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 510 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 511 } 512 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 513 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 514 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 515 } 516 } 517 // Fill in signals that are blocked by all but the VM thread. 518 sigemptyset(&vm_sigs); 519 if (!ReduceSignalUsage) 520 sigaddset(&vm_sigs, BREAK_SIGNAL); 521 debug_only(signal_sets_initialized = true); 522 523 } 524 525 // These are signals that are unblocked while a thread is running Java. 526 // (For some reason, they get blocked by default.) 527 sigset_t* os::Linux::unblocked_signals() { 528 assert(signal_sets_initialized, "Not initialized"); 529 return &unblocked_sigs; 530 } 531 532 // These are the signals that are blocked while a (non-VM) thread is 533 // running Java. Only the VM thread handles these signals. 534 sigset_t* os::Linux::vm_signals() { 535 assert(signal_sets_initialized, "Not initialized"); 536 return &vm_sigs; 537 } 538 539 // These are signals that are blocked during cond_wait to allow debugger in 540 sigset_t* os::Linux::allowdebug_blocked_signals() { 541 assert(signal_sets_initialized, "Not initialized"); 542 return &allowdebug_blocked_sigs; 543 } 544 545 void os::Linux::hotspot_sigmask(Thread* thread) { 546 547 //Save caller's signal mask before setting VM signal mask 548 sigset_t caller_sigmask; 549 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 550 551 OSThread* osthread = thread->osthread(); 552 osthread->set_caller_sigmask(caller_sigmask); 553 554 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 555 556 if (!ReduceSignalUsage) { 557 if (thread->is_VM_thread()) { 558 // Only the VM thread handles BREAK_SIGNAL ... 559 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 560 } else { 561 // ... all other threads block BREAK_SIGNAL 562 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 563 } 564 } 565 } 566 567 ////////////////////////////////////////////////////////////////////////////// 568 // detecting pthread library 569 570 void os::Linux::libpthread_init() { 571 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 572 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 573 // generic name for earlier versions. 574 // Define macros here so we can build HotSpot on old systems. 575 # ifndef _CS_GNU_LIBC_VERSION 576 # define _CS_GNU_LIBC_VERSION 2 577 # endif 578 # ifndef _CS_GNU_LIBPTHREAD_VERSION 579 # define _CS_GNU_LIBPTHREAD_VERSION 3 580 # endif 581 582 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 583 if (n > 0) { 584 char *str = (char *)malloc(n, mtInternal); 585 confstr(_CS_GNU_LIBC_VERSION, str, n); 586 os::Linux::set_glibc_version(str); 587 } else { 588 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 589 static char _gnu_libc_version[32]; 590 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 591 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 592 os::Linux::set_glibc_version(_gnu_libc_version); 593 } 594 595 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 596 if (n > 0) { 597 char *str = (char *)malloc(n, mtInternal); 598 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 599 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 600 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 601 // is the case. LinuxThreads has a hard limit on max number of threads. 602 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 603 // On the other hand, NPTL does not have such a limit, sysconf() 604 // will return -1 and errno is not changed. Check if it is really NPTL. 605 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 606 strstr(str, "NPTL") && 607 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 608 free(str); 609 os::Linux::set_libpthread_version("linuxthreads"); 610 } else { 611 os::Linux::set_libpthread_version(str); 612 } 613 } else { 614 // glibc before 2.3.2 only has LinuxThreads. 615 os::Linux::set_libpthread_version("linuxthreads"); 616 } 617 618 if (strstr(libpthread_version(), "NPTL")) { 619 os::Linux::set_is_NPTL(); 620 } else { 621 os::Linux::set_is_LinuxThreads(); 622 } 623 624 // LinuxThreads have two flavors: floating-stack mode, which allows variable 625 // stack size; and fixed-stack mode. NPTL is always floating-stack. 626 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 627 os::Linux::set_is_floating_stack(); 628 } 629 } 630 631 ///////////////////////////////////////////////////////////////////////////// 632 // thread stack 633 634 // Force Linux kernel to expand current thread stack. If "bottom" is close 635 // to the stack guard, caller should block all signals. 636 // 637 // MAP_GROWSDOWN: 638 // A special mmap() flag that is used to implement thread stacks. It tells 639 // kernel that the memory region should extend downwards when needed. This 640 // allows early versions of LinuxThreads to only mmap the first few pages 641 // when creating a new thread. Linux kernel will automatically expand thread 642 // stack as needed (on page faults). 643 // 644 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 645 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 646 // region, it's hard to tell if the fault is due to a legitimate stack 647 // access or because of reading/writing non-exist memory (e.g. buffer 648 // overrun). As a rule, if the fault happens below current stack pointer, 649 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 650 // application (see Linux kernel fault.c). 651 // 652 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 653 // stack overflow detection. 654 // 655 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 656 // not use this flag. However, the stack of initial thread is not created 657 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 658 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 659 // and then attach the thread to JVM. 660 // 661 // To get around the problem and allow stack banging on Linux, we need to 662 // manually expand thread stack after receiving the SIGSEGV. 663 // 664 // There are two ways to expand thread stack to address "bottom", we used 665 // both of them in JVM before 1.5: 666 // 1. adjust stack pointer first so that it is below "bottom", and then 667 // touch "bottom" 668 // 2. mmap() the page in question 669 // 670 // Now alternate signal stack is gone, it's harder to use 2. For instance, 671 // if current sp is already near the lower end of page 101, and we need to 672 // call mmap() to map page 100, it is possible that part of the mmap() frame 673 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 674 // That will destroy the mmap() frame and cause VM to crash. 675 // 676 // The following code works by adjusting sp first, then accessing the "bottom" 677 // page to force a page fault. Linux kernel will then automatically expand the 678 // stack mapping. 679 // 680 // _expand_stack_to() assumes its frame size is less than page size, which 681 // should always be true if the function is not inlined. 682 683 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 684 #define NOINLINE 685 #else 686 #define NOINLINE __attribute__ ((noinline)) 687 #endif 688 689 static void _expand_stack_to(address bottom) NOINLINE; 690 691 static void _expand_stack_to(address bottom) { 692 address sp; 693 size_t size; 694 volatile char *p; 695 696 // Adjust bottom to point to the largest address within the same page, it 697 // gives us a one-page buffer if alloca() allocates slightly more memory. 698 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 699 bottom += os::Linux::page_size() - 1; 700 701 // sp might be slightly above current stack pointer; if that's the case, we 702 // will alloca() a little more space than necessary, which is OK. Don't use 703 // os::current_stack_pointer(), as its result can be slightly below current 704 // stack pointer, causing us to not alloca enough to reach "bottom". 705 sp = (address)&sp; 706 707 if (sp > bottom) { 708 size = sp - bottom; 709 p = (volatile char *)alloca(size); 710 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 711 p[0] = '\0'; 712 } 713 } 714 715 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 716 assert(t!=NULL, "just checking"); 717 assert(t->osthread()->expanding_stack(), "expand should be set"); 718 assert(t->stack_base() != NULL, "stack_base was not initialized"); 719 720 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 721 sigset_t mask_all, old_sigset; 722 sigfillset(&mask_all); 723 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 724 _expand_stack_to(addr); 725 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 726 return true; 727 } 728 return false; 729 } 730 731 ////////////////////////////////////////////////////////////////////////////// 732 // create new thread 733 734 static address highest_vm_reserved_address(); 735 736 // check if it's safe to start a new thread 737 static bool _thread_safety_check(Thread* thread) { 738 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 739 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 740 // Heap is mmap'ed at lower end of memory space. Thread stacks are 741 // allocated (MAP_FIXED) from high address space. Every thread stack 742 // occupies a fixed size slot (usually 2Mbytes, but user can change 743 // it to other values if they rebuild LinuxThreads). 744 // 745 // Problem with MAP_FIXED is that mmap() can still succeed even part of 746 // the memory region has already been mmap'ed. That means if we have too 747 // many threads and/or very large heap, eventually thread stack will 748 // collide with heap. 749 // 750 // Here we try to prevent heap/stack collision by comparing current 751 // stack bottom with the highest address that has been mmap'ed by JVM 752 // plus a safety margin for memory maps created by native code. 753 // 754 // This feature can be disabled by setting ThreadSafetyMargin to 0 755 // 756 if (ThreadSafetyMargin > 0) { 757 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 758 759 // not safe if our stack extends below the safety margin 760 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 761 } else { 762 return true; 763 } 764 } else { 765 // Floating stack LinuxThreads or NPTL: 766 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 767 // there's not enough space left, pthread_create() will fail. If we come 768 // here, that means enough space has been reserved for stack. 769 return true; 770 } 771 } 772 773 // Thread start routine for all newly created threads 774 static void *java_start(Thread *thread) { 775 // Try to randomize the cache line index of hot stack frames. 776 // This helps when threads of the same stack traces evict each other's 777 // cache lines. The threads can be either from the same JVM instance, or 778 // from different JVM instances. The benefit is especially true for 779 // processors with hyperthreading technology. 780 static int counter = 0; 781 int pid = os::current_process_id(); 782 alloca(((pid ^ counter++) & 7) * 128); 783 784 ThreadLocalStorage::set_thread(thread); 785 786 OSThread* osthread = thread->osthread(); 787 Monitor* sync = osthread->startThread_lock(); 788 789 // non floating stack LinuxThreads needs extra check, see above 790 if (!_thread_safety_check(thread)) { 791 // notify parent thread 792 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 793 osthread->set_state(ZOMBIE); 794 sync->notify_all(); 795 return NULL; 796 } 797 798 // thread_id is kernel thread id (similar to Solaris LWP id) 799 osthread->set_thread_id(os::Linux::gettid()); 800 801 if (UseNUMA) { 802 int lgrp_id = os::numa_get_group_id(); 803 if (lgrp_id != -1) { 804 thread->set_lgrp_id(lgrp_id); 805 } 806 } 807 // initialize signal mask for this thread 808 os::Linux::hotspot_sigmask(thread); 809 810 // initialize floating point control register 811 os::Linux::init_thread_fpu_state(); 812 813 // handshaking with parent thread 814 { 815 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 816 817 // notify parent thread 818 osthread->set_state(INITIALIZED); 819 sync->notify_all(); 820 821 // wait until os::start_thread() 822 while (osthread->get_state() == INITIALIZED) { 823 sync->wait(Mutex::_no_safepoint_check_flag); 824 } 825 } 826 827 // call one more level start routine 828 thread->run(); 829 830 return 0; 831 } 832 833 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 834 assert(thread->osthread() == NULL, "caller responsible"); 835 836 // Allocate the OSThread object 837 OSThread* osthread = new OSThread(NULL, NULL); 838 if (osthread == NULL) { 839 return false; 840 } 841 842 // set the correct thread state 843 osthread->set_thread_type(thr_type); 844 845 // Initial state is ALLOCATED but not INITIALIZED 846 osthread->set_state(ALLOCATED); 847 848 thread->set_osthread(osthread); 849 850 // init thread attributes 851 pthread_attr_t attr; 852 pthread_attr_init(&attr); 853 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 854 855 // stack size 856 if (os::Linux::supports_variable_stack_size()) { 857 // calculate stack size if it's not specified by caller 858 if (stack_size == 0) { 859 stack_size = os::Linux::default_stack_size(thr_type); 860 861 switch (thr_type) { 862 case os::java_thread: 863 // Java threads use ThreadStackSize which default value can be 864 // changed with the flag -Xss 865 assert (JavaThread::stack_size_at_create() > 0, "this should be set"); 866 stack_size = JavaThread::stack_size_at_create(); 867 break; 868 case os::compiler_thread: 869 if (CompilerThreadStackSize > 0) { 870 stack_size = (size_t)(CompilerThreadStackSize * K); 871 break; 872 } // else fall through: 873 // use VMThreadStackSize if CompilerThreadStackSize is not defined 874 case os::vm_thread: 875 case os::pgc_thread: 876 case os::cgc_thread: 877 case os::watcher_thread: 878 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 879 break; 880 } 881 } 882 883 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 884 pthread_attr_setstacksize(&attr, stack_size); 885 } else { 886 // let pthread_create() pick the default value. 887 } 888 889 // glibc guard page 890 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 891 892 ThreadState state; 893 894 { 895 // Serialize thread creation if we are running with fixed stack LinuxThreads 896 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 897 if (lock) { 898 os::Linux::createThread_lock()->lock_without_safepoint_check(); 899 } 900 901 pthread_t tid; 902 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 903 904 pthread_attr_destroy(&attr); 905 906 if (ret != 0) { 907 if (PrintMiscellaneous && (Verbose || WizardMode)) { 908 perror("pthread_create()"); 909 } 910 // Need to clean up stuff we've allocated so far 911 thread->set_osthread(NULL); 912 delete osthread; 913 if (lock) os::Linux::createThread_lock()->unlock(); 914 return false; 915 } 916 917 // Store pthread info into the OSThread 918 osthread->set_pthread_id(tid); 919 920 // Wait until child thread is either initialized or aborted 921 { 922 Monitor* sync_with_child = osthread->startThread_lock(); 923 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 924 while ((state = osthread->get_state()) == ALLOCATED) { 925 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 926 } 927 } 928 929 if (lock) { 930 os::Linux::createThread_lock()->unlock(); 931 } 932 } 933 934 // Aborted due to thread limit being reached 935 if (state == ZOMBIE) { 936 thread->set_osthread(NULL); 937 delete osthread; 938 return false; 939 } 940 941 // The thread is returned suspended (in state INITIALIZED), 942 // and is started higher up in the call chain 943 assert(state == INITIALIZED, "race condition"); 944 return true; 945 } 946 947 ///////////////////////////////////////////////////////////////////////////// 948 // attach existing thread 949 950 // bootstrap the main thread 951 bool os::create_main_thread(JavaThread* thread) { 952 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 953 return create_attached_thread(thread); 954 } 955 956 bool os::create_attached_thread(JavaThread* thread) { 957 #ifdef ASSERT 958 thread->verify_not_published(); 959 #endif 960 961 // Allocate the OSThread object 962 OSThread* osthread = new OSThread(NULL, NULL); 963 964 if (osthread == NULL) { 965 return false; 966 } 967 968 // Store pthread info into the OSThread 969 osthread->set_thread_id(os::Linux::gettid()); 970 osthread->set_pthread_id(::pthread_self()); 971 972 // initialize floating point control register 973 os::Linux::init_thread_fpu_state(); 974 975 // Initial thread state is RUNNABLE 976 osthread->set_state(RUNNABLE); 977 978 thread->set_osthread(osthread); 979 980 if (UseNUMA) { 981 int lgrp_id = os::numa_get_group_id(); 982 if (lgrp_id != -1) { 983 thread->set_lgrp_id(lgrp_id); 984 } 985 } 986 987 if (os::Linux::is_initial_thread()) { 988 // If current thread is initial thread, its stack is mapped on demand, 989 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 990 // the entire stack region to avoid SEGV in stack banging. 991 // It is also useful to get around the heap-stack-gap problem on SuSE 992 // kernel (see 4821821 for details). We first expand stack to the top 993 // of yellow zone, then enable stack yellow zone (order is significant, 994 // enabling yellow zone first will crash JVM on SuSE Linux), so there 995 // is no gap between the last two virtual memory regions. 996 997 JavaThread *jt = (JavaThread *)thread; 998 address addr = jt->stack_yellow_zone_base(); 999 assert(addr != NULL, "initialization problem?"); 1000 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 1001 1002 osthread->set_expanding_stack(); 1003 os::Linux::manually_expand_stack(jt, addr); 1004 osthread->clear_expanding_stack(); 1005 } 1006 1007 // initialize signal mask for this thread 1008 // and save the caller's signal mask 1009 os::Linux::hotspot_sigmask(thread); 1010 1011 return true; 1012 } 1013 1014 void os::pd_start_thread(Thread* thread) { 1015 OSThread * osthread = thread->osthread(); 1016 assert(osthread->get_state() != INITIALIZED, "just checking"); 1017 Monitor* sync_with_child = osthread->startThread_lock(); 1018 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 1019 sync_with_child->notify(); 1020 } 1021 1022 // Free Linux resources related to the OSThread 1023 void os::free_thread(OSThread* osthread) { 1024 assert(osthread != NULL, "osthread not set"); 1025 1026 if (Thread::current()->osthread() == osthread) { 1027 // Restore caller's signal mask 1028 sigset_t sigmask = osthread->caller_sigmask(); 1029 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1030 } 1031 1032 delete osthread; 1033 } 1034 1035 ////////////////////////////////////////////////////////////////////////////// 1036 // thread local storage 1037 1038 // Restore the thread pointer if the destructor is called. This is in case 1039 // someone from JNI code sets up a destructor with pthread_key_create to run 1040 // detachCurrentThread on thread death. Unless we restore the thread pointer we 1041 // will hang or crash. When detachCurrentThread is called the key will be set 1042 // to null and we will not be called again. If detachCurrentThread is never 1043 // called we could loop forever depending on the pthread implementation. 1044 static void restore_thread_pointer(void* p) { 1045 Thread* thread = (Thread*) p; 1046 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); 1047 } 1048 1049 int os::allocate_thread_local_storage() { 1050 pthread_key_t key; 1051 int rslt = pthread_key_create(&key, restore_thread_pointer); 1052 assert(rslt == 0, "cannot allocate thread local storage"); 1053 return (int)key; 1054 } 1055 1056 // Note: This is currently not used by VM, as we don't destroy TLS key 1057 // on VM exit. 1058 void os::free_thread_local_storage(int index) { 1059 int rslt = pthread_key_delete((pthread_key_t)index); 1060 assert(rslt == 0, "invalid index"); 1061 } 1062 1063 void os::thread_local_storage_at_put(int index, void* value) { 1064 int rslt = pthread_setspecific((pthread_key_t)index, value); 1065 assert(rslt == 0, "pthread_setspecific failed"); 1066 } 1067 1068 extern "C" Thread* get_thread() { 1069 return ThreadLocalStorage::thread(); 1070 } 1071 1072 ////////////////////////////////////////////////////////////////////////////// 1073 // initial thread 1074 1075 // Check if current thread is the initial thread, similar to Solaris thr_main. 1076 bool os::Linux::is_initial_thread(void) { 1077 char dummy; 1078 // If called before init complete, thread stack bottom will be null. 1079 // Can be called if fatal error occurs before initialization. 1080 if (initial_thread_stack_bottom() == NULL) return false; 1081 assert(initial_thread_stack_bottom() != NULL && 1082 initial_thread_stack_size() != 0, 1083 "os::init did not locate initial thread's stack region"); 1084 if ((address)&dummy >= initial_thread_stack_bottom() && 1085 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1086 return true; 1087 else return false; 1088 } 1089 1090 // Find the virtual memory area that contains addr 1091 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1092 FILE *fp = fopen("/proc/self/maps", "r"); 1093 if (fp) { 1094 address low, high; 1095 while (!feof(fp)) { 1096 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1097 if (low <= addr && addr < high) { 1098 if (vma_low) *vma_low = low; 1099 if (vma_high) *vma_high = high; 1100 fclose (fp); 1101 return true; 1102 } 1103 } 1104 for (;;) { 1105 int ch = fgetc(fp); 1106 if (ch == EOF || ch == (int)'\n') break; 1107 } 1108 } 1109 fclose(fp); 1110 } 1111 return false; 1112 } 1113 1114 // Locate initial thread stack. This special handling of initial thread stack 1115 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1116 // bogus value for initial thread. 1117 void os::Linux::capture_initial_stack(size_t max_size) { 1118 // stack size is the easy part, get it from RLIMIT_STACK 1119 size_t stack_size; 1120 struct rlimit rlim; 1121 getrlimit(RLIMIT_STACK, &rlim); 1122 stack_size = rlim.rlim_cur; 1123 1124 // 6308388: a bug in ld.so will relocate its own .data section to the 1125 // lower end of primordial stack; reduce ulimit -s value a little bit 1126 // so we won't install guard page on ld.so's data section. 1127 stack_size -= 2 * page_size(); 1128 1129 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1130 // 7.1, in both cases we will get 2G in return value. 1131 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1132 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1133 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1134 // in case other parts in glibc still assumes 2M max stack size. 1135 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1136 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1137 if (stack_size > 2 * K * K IA64_ONLY(*2)) 1138 stack_size = 2 * K * K IA64_ONLY(*2); 1139 // Try to figure out where the stack base (top) is. This is harder. 1140 // 1141 // When an application is started, glibc saves the initial stack pointer in 1142 // a global variable "__libc_stack_end", which is then used by system 1143 // libraries. __libc_stack_end should be pretty close to stack top. The 1144 // variable is available since the very early days. However, because it is 1145 // a private interface, it could disappear in the future. 1146 // 1147 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1148 // to __libc_stack_end, it is very close to stack top, but isn't the real 1149 // stack top. Note that /proc may not exist if VM is running as a chroot 1150 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1151 // /proc/<pid>/stat could change in the future (though unlikely). 1152 // 1153 // We try __libc_stack_end first. If that doesn't work, look for 1154 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1155 // as a hint, which should work well in most cases. 1156 1157 uintptr_t stack_start; 1158 1159 // try __libc_stack_end first 1160 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1161 if (p && *p) { 1162 stack_start = *p; 1163 } else { 1164 // see if we can get the start_stack field from /proc/self/stat 1165 FILE *fp; 1166 int pid; 1167 char state; 1168 int ppid; 1169 int pgrp; 1170 int session; 1171 int nr; 1172 int tpgrp; 1173 unsigned long flags; 1174 unsigned long minflt; 1175 unsigned long cminflt; 1176 unsigned long majflt; 1177 unsigned long cmajflt; 1178 unsigned long utime; 1179 unsigned long stime; 1180 long cutime; 1181 long cstime; 1182 long prio; 1183 long nice; 1184 long junk; 1185 long it_real; 1186 uintptr_t start; 1187 uintptr_t vsize; 1188 intptr_t rss; 1189 uintptr_t rsslim; 1190 uintptr_t scodes; 1191 uintptr_t ecode; 1192 int i; 1193 1194 // Figure what the primordial thread stack base is. Code is inspired 1195 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1196 // followed by command name surrounded by parentheses, state, etc. 1197 char stat[2048]; 1198 int statlen; 1199 1200 fp = fopen("/proc/self/stat", "r"); 1201 if (fp) { 1202 statlen = fread(stat, 1, 2047, fp); 1203 stat[statlen] = '\0'; 1204 fclose(fp); 1205 1206 // Skip pid and the command string. Note that we could be dealing with 1207 // weird command names, e.g. user could decide to rename java launcher 1208 // to "java 1.4.2 :)", then the stat file would look like 1209 // 1234 (java 1.4.2 :)) R ... ... 1210 // We don't really need to know the command string, just find the last 1211 // occurrence of ")" and then start parsing from there. See bug 4726580. 1212 char * s = strrchr(stat, ')'); 1213 1214 i = 0; 1215 if (s) { 1216 // Skip blank chars 1217 do s++; while (isspace(*s)); 1218 1219 #define _UFM UINTX_FORMAT 1220 #define _DFM INTX_FORMAT 1221 1222 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1223 /* 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 */ 1224 i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld " _UFM _UFM _DFM _UFM _UFM _UFM _UFM, 1225 &state, /* 3 %c */ 1226 &ppid, /* 4 %d */ 1227 &pgrp, /* 5 %d */ 1228 &session, /* 6 %d */ 1229 &nr, /* 7 %d */ 1230 &tpgrp, /* 8 %d */ 1231 &flags, /* 9 %lu */ 1232 &minflt, /* 10 %lu */ 1233 &cminflt, /* 11 %lu */ 1234 &majflt, /* 12 %lu */ 1235 &cmajflt, /* 13 %lu */ 1236 &utime, /* 14 %lu */ 1237 &stime, /* 15 %lu */ 1238 &cutime, /* 16 %ld */ 1239 &cstime, /* 17 %ld */ 1240 &prio, /* 18 %ld */ 1241 &nice, /* 19 %ld */ 1242 &junk, /* 20 %ld */ 1243 &it_real, /* 21 %ld */ 1244 &start, /* 22 UINTX_FORMAT */ 1245 &vsize, /* 23 UINTX_FORMAT */ 1246 &rss, /* 24 INTX_FORMAT */ 1247 &rsslim, /* 25 UINTX_FORMAT */ 1248 &scodes, /* 26 UINTX_FORMAT */ 1249 &ecode, /* 27 UINTX_FORMAT */ 1250 &stack_start); /* 28 UINTX_FORMAT */ 1251 } 1252 1253 #undef _UFM 1254 #undef _DFM 1255 1256 if (i != 28 - 2) { 1257 assert(false, "Bad conversion from /proc/self/stat"); 1258 // product mode - assume we are the initial thread, good luck in the 1259 // embedded case. 1260 warning("Can't detect initial thread stack location - bad conversion"); 1261 stack_start = (uintptr_t) &rlim; 1262 } 1263 } else { 1264 // For some reason we can't open /proc/self/stat (for example, running on 1265 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1266 // most cases, so don't abort: 1267 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1268 stack_start = (uintptr_t) &rlim; 1269 } 1270 } 1271 1272 // Now we have a pointer (stack_start) very close to the stack top, the 1273 // next thing to do is to figure out the exact location of stack top. We 1274 // can find out the virtual memory area that contains stack_start by 1275 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1276 // and its upper limit is the real stack top. (again, this would fail if 1277 // running inside chroot, because /proc may not exist.) 1278 1279 uintptr_t stack_top; 1280 address low, high; 1281 if (find_vma((address)stack_start, &low, &high)) { 1282 // success, "high" is the true stack top. (ignore "low", because initial 1283 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1284 stack_top = (uintptr_t)high; 1285 } else { 1286 // failed, likely because /proc/self/maps does not exist 1287 warning("Can't detect initial thread stack location - find_vma failed"); 1288 // best effort: stack_start is normally within a few pages below the real 1289 // stack top, use it as stack top, and reduce stack size so we won't put 1290 // guard page outside stack. 1291 stack_top = stack_start; 1292 stack_size -= 16 * page_size(); 1293 } 1294 1295 // stack_top could be partially down the page so align it 1296 stack_top = align_size_up(stack_top, page_size()); 1297 1298 if (max_size && stack_size > max_size) { 1299 _initial_thread_stack_size = max_size; 1300 } else { 1301 _initial_thread_stack_size = stack_size; 1302 } 1303 1304 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1305 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1306 } 1307 1308 //////////////////////////////////////////////////////////////////////////////// 1309 // time support 1310 1311 // Time since start-up in seconds to a fine granularity. 1312 // Used by VMSelfDestructTimer and the MemProfiler. 1313 double os::elapsedTime() { 1314 1315 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution 1316 } 1317 1318 jlong os::elapsed_counter() { 1319 return javaTimeNanos() - initial_time_count; 1320 } 1321 1322 jlong os::elapsed_frequency() { 1323 return NANOSECS_PER_SEC; // nanosecond resolution 1324 } 1325 1326 bool os::supports_vtime() { return true; } 1327 bool os::enable_vtime() { return false; } 1328 bool os::vtime_enabled() { return false; } 1329 1330 double os::elapsedVTime() { 1331 struct rusage usage; 1332 int retval = getrusage(RUSAGE_THREAD, &usage); 1333 if (retval == 0) { 1334 return (double) (usage.ru_utime.tv_sec + usage.ru_stime.tv_sec) + (double) (usage.ru_utime.tv_usec + usage.ru_stime.tv_usec) / (1000 * 1000); 1335 } else { 1336 // better than nothing, but not much 1337 return elapsedTime(); 1338 } 1339 } 1340 1341 jlong os::javaTimeMillis() { 1342 timeval time; 1343 int status = gettimeofday(&time, NULL); 1344 assert(status != -1, "linux error"); 1345 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1346 } 1347 1348 #ifndef CLOCK_MONOTONIC 1349 #define CLOCK_MONOTONIC (1) 1350 #endif 1351 1352 void os::Linux::clock_init() { 1353 // we do dlopen's in this particular order due to bug in linux 1354 // dynamical loader (see 6348968) leading to crash on exit 1355 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1356 if (handle == NULL) { 1357 handle = dlopen("librt.so", RTLD_LAZY); 1358 } 1359 1360 if (handle) { 1361 int (*clock_getres_func)(clockid_t, struct timespec*) = 1362 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1363 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1364 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1365 if (clock_getres_func && clock_gettime_func) { 1366 // See if monotonic clock is supported by the kernel. Note that some 1367 // early implementations simply return kernel jiffies (updated every 1368 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1369 // for nano time (though the monotonic property is still nice to have). 1370 // It's fixed in newer kernels, however clock_getres() still returns 1371 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1372 // resolution for now. Hopefully as people move to new kernels, this 1373 // won't be a problem. 1374 struct timespec res; 1375 struct timespec tp; 1376 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1377 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1378 // yes, monotonic clock is supported 1379 _clock_gettime = clock_gettime_func; 1380 return; 1381 } else { 1382 // close librt if there is no monotonic clock 1383 dlclose(handle); 1384 } 1385 } 1386 } 1387 warning("No monotonic clock was available - timed services may " \ 1388 "be adversely affected if the time-of-day clock changes"); 1389 } 1390 1391 #ifndef SYS_clock_getres 1392 1393 #if defined(IA32) || defined(AMD64) 1394 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1395 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1396 #else 1397 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1398 #define sys_clock_getres(x,y) -1 1399 #endif 1400 1401 #else 1402 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1403 #endif 1404 1405 void os::Linux::fast_thread_clock_init() { 1406 if (!UseLinuxPosixThreadCPUClocks) { 1407 return; 1408 } 1409 clockid_t clockid; 1410 struct timespec tp; 1411 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1412 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1413 1414 // Switch to using fast clocks for thread cpu time if 1415 // the sys_clock_getres() returns 0 error code. 1416 // Note, that some kernels may support the current thread 1417 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1418 // returned by the pthread_getcpuclockid(). 1419 // If the fast Posix clocks are supported then the sys_clock_getres() 1420 // must return at least tp.tv_sec == 0 which means a resolution 1421 // better than 1 sec. This is extra check for reliability. 1422 1423 if(pthread_getcpuclockid_func && 1424 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1425 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1426 1427 _supports_fast_thread_cpu_time = true; 1428 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1429 } 1430 } 1431 1432 jlong os::javaTimeNanos() { 1433 if (os::supports_monotonic_clock()) { 1434 struct timespec tp; 1435 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1436 assert(status == 0, "gettime error"); 1437 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1438 return result; 1439 } else { 1440 timeval time; 1441 int status = gettimeofday(&time, NULL); 1442 assert(status != -1, "linux error"); 1443 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1444 return 1000 * usecs; 1445 } 1446 } 1447 1448 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1449 if (os::supports_monotonic_clock()) { 1450 info_ptr->max_value = ALL_64_BITS; 1451 1452 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1453 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1454 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1455 } else { 1456 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1457 info_ptr->max_value = ALL_64_BITS; 1458 1459 // gettimeofday is a real time clock so it skips 1460 info_ptr->may_skip_backward = true; 1461 info_ptr->may_skip_forward = true; 1462 } 1463 1464 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1465 } 1466 1467 // Return the real, user, and system times in seconds from an 1468 // arbitrary fixed point in the past. 1469 bool os::getTimesSecs(double* process_real_time, 1470 double* process_user_time, 1471 double* process_system_time) { 1472 struct tms ticks; 1473 clock_t real_ticks = times(&ticks); 1474 1475 if (real_ticks == (clock_t) (-1)) { 1476 return false; 1477 } else { 1478 double ticks_per_second = (double) clock_tics_per_sec; 1479 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1480 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1481 *process_real_time = ((double) real_ticks) / ticks_per_second; 1482 1483 return true; 1484 } 1485 } 1486 1487 1488 char * os::local_time_string(char *buf, size_t buflen) { 1489 struct tm t; 1490 time_t long_time; 1491 time(&long_time); 1492 localtime_r(&long_time, &t); 1493 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1494 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1495 t.tm_hour, t.tm_min, t.tm_sec); 1496 return buf; 1497 } 1498 1499 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1500 return localtime_r(clock, res); 1501 } 1502 1503 //////////////////////////////////////////////////////////////////////////////// 1504 // runtime exit support 1505 1506 // Note: os::shutdown() might be called very early during initialization, or 1507 // called from signal handler. Before adding something to os::shutdown(), make 1508 // sure it is async-safe and can handle partially initialized VM. 1509 void os::shutdown() { 1510 1511 // allow PerfMemory to attempt cleanup of any persistent resources 1512 perfMemory_exit(); 1513 1514 // needs to remove object in file system 1515 AttachListener::abort(); 1516 1517 // flush buffered output, finish log files 1518 ostream_abort(); 1519 1520 // Check for abort hook 1521 abort_hook_t abort_hook = Arguments::abort_hook(); 1522 if (abort_hook != NULL) { 1523 abort_hook(); 1524 } 1525 1526 } 1527 1528 // Note: os::abort() might be called very early during initialization, or 1529 // called from signal handler. Before adding something to os::abort(), make 1530 // sure it is async-safe and can handle partially initialized VM. 1531 void os::abort(bool dump_core) { 1532 os::shutdown(); 1533 if (dump_core) { 1534 #ifndef PRODUCT 1535 fdStream out(defaultStream::output_fd()); 1536 out.print_raw("Current thread is "); 1537 char buf[16]; 1538 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1539 out.print_raw_cr(buf); 1540 out.print_raw_cr("Dumping core ..."); 1541 #endif 1542 ::abort(); // dump core 1543 } 1544 1545 ::exit(1); 1546 } 1547 1548 // Die immediately, no exit hook, no abort hook, no cleanup. 1549 void os::die() { 1550 // _exit() on LinuxThreads only kills current thread 1551 ::abort(); 1552 } 1553 1554 // unused on linux for now. 1555 void os::set_error_file(const char *logfile) {} 1556 1557 1558 // This method is a copy of JDK's sysGetLastErrorString 1559 // from src/solaris/hpi/src/system_md.c 1560 1561 size_t os::lasterror(char *buf, size_t len) { 1562 1563 if (errno == 0) return 0; 1564 1565 const char *s = ::strerror(errno); 1566 size_t n = ::strlen(s); 1567 if (n >= len) { 1568 n = len - 1; 1569 } 1570 ::strncpy(buf, s, n); 1571 buf[n] = '\0'; 1572 return n; 1573 } 1574 1575 intx os::current_thread_id() { return (intx)pthread_self(); } 1576 int os::current_process_id() { 1577 1578 // Under the old linux thread library, linux gives each thread 1579 // its own process id. Because of this each thread will return 1580 // a different pid if this method were to return the result 1581 // of getpid(2). Linux provides no api that returns the pid 1582 // of the launcher thread for the vm. This implementation 1583 // returns a unique pid, the pid of the launcher thread 1584 // that starts the vm 'process'. 1585 1586 // Under the NPTL, getpid() returns the same pid as the 1587 // launcher thread rather than a unique pid per thread. 1588 // Use gettid() if you want the old pre NPTL behaviour. 1589 1590 // if you are looking for the result of a call to getpid() that 1591 // returns a unique pid for the calling thread, then look at the 1592 // OSThread::thread_id() method in osThread_linux.hpp file 1593 1594 return (int)(_initial_pid ? _initial_pid : getpid()); 1595 } 1596 1597 // DLL functions 1598 1599 const char* os::dll_file_extension() { return ".so"; } 1600 1601 // This must be hard coded because it's the system's temporary 1602 // directory not the java application's temp directory, ala java.io.tmpdir. 1603 const char* os::get_temp_directory() { return "/tmp"; } 1604 1605 static bool file_exists(const char* filename) { 1606 struct stat statbuf; 1607 if (filename == NULL || strlen(filename) == 0) { 1608 return false; 1609 } 1610 return os::stat(filename, &statbuf) == 0; 1611 } 1612 1613 bool os::dll_build_name(char* buffer, size_t buflen, 1614 const char* pname, const char* fname) { 1615 bool retval = false; 1616 // Copied from libhpi 1617 const size_t pnamelen = pname ? strlen(pname) : 0; 1618 1619 // Return error on buffer overflow. 1620 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1621 return retval; 1622 } 1623 1624 if (pnamelen == 0) { 1625 snprintf(buffer, buflen, "lib%s.so", fname); 1626 retval = true; 1627 } else if (strchr(pname, *os::path_separator()) != NULL) { 1628 int n; 1629 char** pelements = split_path(pname, &n); 1630 if (pelements == NULL) { 1631 return false; 1632 } 1633 for (int i = 0 ; i < n ; i++) { 1634 // Really shouldn't be NULL, but check can't hurt 1635 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1636 continue; // skip the empty path values 1637 } 1638 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1639 if (file_exists(buffer)) { 1640 retval = true; 1641 break; 1642 } 1643 } 1644 // release the storage 1645 for (int i = 0 ; i < n ; i++) { 1646 if (pelements[i] != NULL) { 1647 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal); 1648 } 1649 } 1650 if (pelements != NULL) { 1651 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal); 1652 } 1653 } else { 1654 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1655 retval = true; 1656 } 1657 return retval; 1658 } 1659 1660 // check if addr is inside libjvm.so 1661 bool os::address_is_in_vm(address addr) { 1662 static address libjvm_base_addr; 1663 Dl_info dlinfo; 1664 1665 if (libjvm_base_addr == NULL) { 1666 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1667 libjvm_base_addr = (address)dlinfo.dli_fbase; 1668 } 1669 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1670 } 1671 1672 if (dladdr((void *)addr, &dlinfo) != 0) { 1673 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1674 } 1675 1676 return false; 1677 } 1678 1679 bool os::dll_address_to_function_name(address addr, char *buf, 1680 int buflen, int *offset) { 1681 // buf is not optional, but offset is optional 1682 assert(buf != NULL, "sanity check"); 1683 1684 Dl_info dlinfo; 1685 1686 if (dladdr((void*)addr, &dlinfo) != 0) { 1687 // see if we have a matching symbol 1688 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1689 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1690 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1691 } 1692 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1693 return true; 1694 } 1695 // no matching symbol so try for just file info 1696 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1697 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1698 buf, buflen, offset, dlinfo.dli_fname)) { 1699 return true; 1700 } 1701 } 1702 } 1703 1704 buf[0] = '\0'; 1705 if (offset != NULL) *offset = -1; 1706 return false; 1707 } 1708 1709 struct _address_to_library_name { 1710 address addr; // input : memory address 1711 size_t buflen; // size of fname 1712 char* fname; // output: library name 1713 address base; // library base addr 1714 }; 1715 1716 static int address_to_library_name_callback(struct dl_phdr_info *info, 1717 size_t size, void *data) { 1718 int i; 1719 bool found = false; 1720 address libbase = NULL; 1721 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1722 1723 // iterate through all loadable segments 1724 for (i = 0; i < info->dlpi_phnum; i++) { 1725 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1726 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1727 // base address of a library is the lowest address of its loaded 1728 // segments. 1729 if (libbase == NULL || libbase > segbase) { 1730 libbase = segbase; 1731 } 1732 // see if 'addr' is within current segment 1733 if (segbase <= d->addr && 1734 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1735 found = true; 1736 } 1737 } 1738 } 1739 1740 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1741 // so dll_address_to_library_name() can fall through to use dladdr() which 1742 // can figure out executable name from argv[0]. 1743 if (found && info->dlpi_name && info->dlpi_name[0]) { 1744 d->base = libbase; 1745 if (d->fname) { 1746 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1747 } 1748 return 1; 1749 } 1750 return 0; 1751 } 1752 1753 bool os::dll_address_to_library_name(address addr, char* buf, 1754 int buflen, int* offset) { 1755 // buf is not optional, but offset is optional 1756 assert(buf != NULL, "sanity check"); 1757 1758 Dl_info dlinfo; 1759 struct _address_to_library_name data; 1760 1761 // There is a bug in old glibc dladdr() implementation that it could resolve 1762 // to wrong library name if the .so file has a base address != NULL. Here 1763 // we iterate through the program headers of all loaded libraries to find 1764 // out which library 'addr' really belongs to. This workaround can be 1765 // removed once the minimum requirement for glibc is moved to 2.3.x. 1766 data.addr = addr; 1767 data.fname = buf; 1768 data.buflen = buflen; 1769 data.base = NULL; 1770 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1771 1772 if (rslt) { 1773 // buf already contains library name 1774 if (offset) *offset = addr - data.base; 1775 return true; 1776 } 1777 if (dladdr((void*)addr, &dlinfo) != 0) { 1778 if (dlinfo.dli_fname != NULL) { 1779 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1780 } 1781 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1782 *offset = addr - (address)dlinfo.dli_fbase; 1783 } 1784 return true; 1785 } 1786 1787 buf[0] = '\0'; 1788 if (offset) *offset = -1; 1789 return false; 1790 } 1791 1792 // Loads .dll/.so and 1793 // in case of error it checks if .dll/.so was built for the 1794 // same architecture as Hotspot is running on 1795 1796 1797 // Remember the stack's state. The Linux dynamic linker will change 1798 // the stack to 'executable' at most once, so we must safepoint only once. 1799 bool os::Linux::_stack_is_executable = false; 1800 1801 // VM operation that loads a library. This is necessary if stack protection 1802 // of the Java stacks can be lost during loading the library. If we 1803 // do not stop the Java threads, they can stack overflow before the stacks 1804 // are protected again. 1805 class VM_LinuxDllLoad: public VM_Operation { 1806 private: 1807 const char *_filename; 1808 char *_ebuf; 1809 int _ebuflen; 1810 void *_lib; 1811 public: 1812 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1813 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1814 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1815 void doit() { 1816 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1817 os::Linux::_stack_is_executable = true; 1818 } 1819 void* loaded_library() { return _lib; } 1820 }; 1821 1822 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1823 { 1824 void * result = NULL; 1825 bool load_attempted = false; 1826 1827 // Check whether the library to load might change execution rights 1828 // of the stack. If they are changed, the protection of the stack 1829 // guard pages will be lost. We need a safepoint to fix this. 1830 // 1831 // See Linux man page execstack(8) for more info. 1832 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1833 ElfFile ef(filename); 1834 if (!ef.specifies_noexecstack()) { 1835 if (!is_init_completed()) { 1836 os::Linux::_stack_is_executable = true; 1837 // This is OK - No Java threads have been created yet, and hence no 1838 // stack guard pages to fix. 1839 // 1840 // This should happen only when you are building JDK7 using a very 1841 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1842 // 1843 // Dynamic loader will make all stacks executable after 1844 // this function returns, and will not do that again. 1845 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1846 } else { 1847 warning("You have loaded library %s which might have disabled stack guard. " 1848 "The VM will try to fix the stack guard now.\n" 1849 "It's highly recommended that you fix the library with " 1850 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1851 filename); 1852 1853 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1854 JavaThread *jt = JavaThread::current(); 1855 if (jt->thread_state() != _thread_in_native) { 1856 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1857 // that requires ExecStack. Cannot enter safe point. Let's give up. 1858 warning("Unable to fix stack guard. Giving up."); 1859 } else { 1860 if (!LoadExecStackDllInVMThread) { 1861 // This is for the case where the DLL has an static 1862 // constructor function that executes JNI code. We cannot 1863 // load such DLLs in the VMThread. 1864 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1865 } 1866 1867 ThreadInVMfromNative tiv(jt); 1868 debug_only(VMNativeEntryWrapper vew;) 1869 1870 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1871 VMThread::execute(&op); 1872 if (LoadExecStackDllInVMThread) { 1873 result = op.loaded_library(); 1874 } 1875 load_attempted = true; 1876 } 1877 } 1878 } 1879 } 1880 1881 if (!load_attempted) { 1882 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1883 } 1884 1885 if (result != NULL) { 1886 // Successful loading 1887 return result; 1888 } 1889 1890 Elf32_Ehdr elf_head; 1891 int diag_msg_max_length=ebuflen-strlen(ebuf); 1892 char* diag_msg_buf=ebuf+strlen(ebuf); 1893 1894 if (diag_msg_max_length==0) { 1895 // No more space in ebuf for additional diagnostics message 1896 return NULL; 1897 } 1898 1899 1900 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1901 1902 if (file_descriptor < 0) { 1903 // Can't open library, report dlerror() message 1904 return NULL; 1905 } 1906 1907 bool failed_to_read_elf_head= 1908 (sizeof(elf_head)!= 1909 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1910 1911 ::close(file_descriptor); 1912 if (failed_to_read_elf_head) { 1913 // file i/o error - report dlerror() msg 1914 return NULL; 1915 } 1916 1917 typedef struct { 1918 Elf32_Half code; // Actual value as defined in elf.h 1919 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1920 char elf_class; // 32 or 64 bit 1921 char endianess; // MSB or LSB 1922 char* name; // String representation 1923 } arch_t; 1924 1925 #ifndef EM_486 1926 #define EM_486 6 /* Intel 80486 */ 1927 #endif 1928 1929 static const arch_t arch_array[]={ 1930 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1931 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1932 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1933 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1934 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1935 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1936 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1937 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1938 #if defined(VM_LITTLE_ENDIAN) 1939 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"}, 1940 #else 1941 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1942 #endif 1943 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1944 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1945 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1946 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1947 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1948 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1949 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1950 }; 1951 1952 #if (defined IA32) 1953 static Elf32_Half running_arch_code=EM_386; 1954 #elif (defined AMD64) 1955 static Elf32_Half running_arch_code=EM_X86_64; 1956 #elif (defined IA64) 1957 static Elf32_Half running_arch_code=EM_IA_64; 1958 #elif (defined __sparc) && (defined _LP64) 1959 static Elf32_Half running_arch_code=EM_SPARCV9; 1960 #elif (defined __sparc) && (!defined _LP64) 1961 static Elf32_Half running_arch_code=EM_SPARC; 1962 #elif (defined __powerpc64__) 1963 static Elf32_Half running_arch_code=EM_PPC64; 1964 #elif (defined __powerpc__) 1965 static Elf32_Half running_arch_code=EM_PPC; 1966 #elif (defined ARM) 1967 static Elf32_Half running_arch_code=EM_ARM; 1968 #elif (defined S390) 1969 static Elf32_Half running_arch_code=EM_S390; 1970 #elif (defined ALPHA) 1971 static Elf32_Half running_arch_code=EM_ALPHA; 1972 #elif (defined MIPSEL) 1973 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1974 #elif (defined PARISC) 1975 static Elf32_Half running_arch_code=EM_PARISC; 1976 #elif (defined MIPS) 1977 static Elf32_Half running_arch_code=EM_MIPS; 1978 #elif (defined M68K) 1979 static Elf32_Half running_arch_code=EM_68K; 1980 #else 1981 #error Method os::dll_load requires that one of following is defined:\ 1982 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1983 #endif 1984 1985 // Identify compatability class for VM's architecture and library's architecture 1986 // Obtain string descriptions for architectures 1987 1988 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1989 int running_arch_index=-1; 1990 1991 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 1992 if (running_arch_code == arch_array[i].code) { 1993 running_arch_index = i; 1994 } 1995 if (lib_arch.code == arch_array[i].code) { 1996 lib_arch.compat_class = arch_array[i].compat_class; 1997 lib_arch.name = arch_array[i].name; 1998 } 1999 } 2000 2001 assert(running_arch_index != -1, 2002 "Didn't find running architecture code (running_arch_code) in arch_array"); 2003 if (running_arch_index == -1) { 2004 // Even though running architecture detection failed 2005 // we may still continue with reporting dlerror() message 2006 return NULL; 2007 } 2008 2009 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 2010 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 2011 return NULL; 2012 } 2013 2014 #ifndef S390 2015 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 2016 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 2017 return NULL; 2018 } 2019 #endif // !S390 2020 2021 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 2022 if ( lib_arch.name!=NULL ) { 2023 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2024 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 2025 lib_arch.name, arch_array[running_arch_index].name); 2026 } else { 2027 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2028 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 2029 lib_arch.code, 2030 arch_array[running_arch_index].name); 2031 } 2032 } 2033 2034 return NULL; 2035 } 2036 2037 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) { 2038 void * result = ::dlopen(filename, RTLD_LAZY); 2039 if (result == NULL) { 2040 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2041 ebuf[ebuflen-1] = '\0'; 2042 } 2043 return result; 2044 } 2045 2046 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) { 2047 void * result = NULL; 2048 if (LoadExecStackDllInVMThread) { 2049 result = dlopen_helper(filename, ebuf, ebuflen); 2050 } 2051 2052 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2053 // library that requires an executable stack, or which does not have this 2054 // stack attribute set, dlopen changes the stack attribute to executable. The 2055 // read protection of the guard pages gets lost. 2056 // 2057 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2058 // may have been queued at the same time. 2059 2060 if (!_stack_is_executable) { 2061 JavaThread *jt = Threads::first(); 2062 2063 while (jt) { 2064 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2065 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2066 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2067 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2068 warning("Attempt to reguard stack yellow zone failed."); 2069 } 2070 } 2071 jt = jt->next(); 2072 } 2073 } 2074 2075 return result; 2076 } 2077 2078 /* 2079 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2080 * chances are you might want to run the generated bits against glibc-2.0 2081 * libdl.so, so always use locking for any version of glibc. 2082 */ 2083 void* os::dll_lookup(void* handle, const char* name) { 2084 pthread_mutex_lock(&dl_mutex); 2085 void* res = dlsym(handle, name); 2086 pthread_mutex_unlock(&dl_mutex); 2087 return res; 2088 } 2089 2090 void* os::get_default_process_handle() { 2091 return (void*)::dlopen(NULL, RTLD_LAZY); 2092 } 2093 2094 static bool _print_ascii_file(const char* filename, outputStream* st) { 2095 int fd = ::open(filename, O_RDONLY); 2096 if (fd == -1) { 2097 return false; 2098 } 2099 2100 char buf[32]; 2101 int bytes; 2102 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2103 st->print_raw(buf, bytes); 2104 } 2105 2106 ::close(fd); 2107 2108 return true; 2109 } 2110 2111 void os::print_dll_info(outputStream *st) { 2112 st->print_cr("Dynamic libraries:"); 2113 2114 char fname[32]; 2115 pid_t pid = os::Linux::gettid(); 2116 2117 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2118 2119 if (!_print_ascii_file(fname, st)) { 2120 st->print("Can not get library information for pid = %d\n", pid); 2121 } 2122 } 2123 2124 void os::print_os_info_brief(outputStream* st) { 2125 os::Linux::print_distro_info(st); 2126 2127 os::Posix::print_uname_info(st); 2128 2129 os::Linux::print_libversion_info(st); 2130 2131 } 2132 2133 void os::print_os_info(outputStream* st) { 2134 st->print("OS:"); 2135 2136 os::Linux::print_distro_info(st); 2137 2138 os::Posix::print_uname_info(st); 2139 2140 // Print warning if unsafe chroot environment detected 2141 if (unsafe_chroot_detected) { 2142 st->print("WARNING!! "); 2143 st->print_cr("%s", unstable_chroot_error); 2144 } 2145 2146 os::Linux::print_libversion_info(st); 2147 2148 os::Posix::print_rlimit_info(st); 2149 2150 os::Posix::print_load_average(st); 2151 2152 os::Linux::print_full_memory_info(st); 2153 } 2154 2155 // Try to identify popular distros. 2156 // Most Linux distributions have a /etc/XXX-release file, which contains 2157 // the OS version string. Newer Linux distributions have a /etc/lsb-release 2158 // file that also contains the OS version string. Some have more than one 2159 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2160 // /etc/redhat-release.), so the order is important. 2161 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2162 // their own specific XXX-release file as well as a redhat-release file. 2163 // Because of this the XXX-release file needs to be searched for before the 2164 // redhat-release file. 2165 // Since Red Hat has a lsb-release file that is not very descriptive the 2166 // search for redhat-release needs to be before lsb-release. 2167 // Since the lsb-release file is the new standard it needs to be searched 2168 // before the older style release files. 2169 // Searching system-release (Red Hat) and os-release (other Linuxes) are a 2170 // next to last resort. The os-release file is a new standard that contains 2171 // distribution information and the system-release file seems to be an old 2172 // standard that has been replaced by the lsb-release and os-release files. 2173 // Searching for the debian_version file is the last resort. It contains 2174 // an informative string like "6.0.6" or "wheezy/sid". Because of this 2175 // "Debian " is printed before the contents of the debian_version file. 2176 void os::Linux::print_distro_info(outputStream* st) { 2177 if (!_print_ascii_file("/etc/oracle-release", st) && 2178 !_print_ascii_file("/etc/mandriva-release", st) && 2179 !_print_ascii_file("/etc/mandrake-release", st) && 2180 !_print_ascii_file("/etc/sun-release", st) && 2181 !_print_ascii_file("/etc/redhat-release", st) && 2182 !_print_ascii_file("/etc/lsb-release", st) && 2183 !_print_ascii_file("/etc/SuSE-release", st) && 2184 !_print_ascii_file("/etc/turbolinux-release", st) && 2185 !_print_ascii_file("/etc/gentoo-release", st) && 2186 !_print_ascii_file("/etc/ltib-release", st) && 2187 !_print_ascii_file("/etc/angstrom-version", st) && 2188 !_print_ascii_file("/etc/system-release", st) && 2189 !_print_ascii_file("/etc/os-release", st)) { 2190 2191 if (file_exists("/etc/debian_version")) { 2192 st->print("Debian "); 2193 _print_ascii_file("/etc/debian_version", st); 2194 } else { 2195 st->print("Linux"); 2196 } 2197 } 2198 st->cr(); 2199 } 2200 2201 void os::Linux::print_libversion_info(outputStream* st) { 2202 // libc, pthread 2203 st->print("libc:"); 2204 st->print("%s ", os::Linux::glibc_version()); 2205 st->print("%s ", os::Linux::libpthread_version()); 2206 if (os::Linux::is_LinuxThreads()) { 2207 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2208 } 2209 st->cr(); 2210 } 2211 2212 void os::Linux::print_full_memory_info(outputStream* st) { 2213 st->print("\n/proc/meminfo:\n"); 2214 _print_ascii_file("/proc/meminfo", st); 2215 st->cr(); 2216 } 2217 2218 void os::print_memory_info(outputStream* st) { 2219 2220 st->print("Memory:"); 2221 st->print(" %dk page", os::vm_page_size()>>10); 2222 2223 // values in struct sysinfo are "unsigned long" 2224 struct sysinfo si; 2225 sysinfo(&si); 2226 2227 st->print(", physical " UINT64_FORMAT "k", 2228 os::physical_memory() >> 10); 2229 st->print("(" UINT64_FORMAT "k free)", 2230 os::available_memory() >> 10); 2231 st->print(", swap " UINT64_FORMAT "k", 2232 ((jlong)si.totalswap * si.mem_unit) >> 10); 2233 st->print("(" UINT64_FORMAT "k free)", 2234 ((jlong)si.freeswap * si.mem_unit) >> 10); 2235 st->cr(); 2236 } 2237 2238 void os::pd_print_cpu_info(outputStream* st) { 2239 st->print("\n/proc/cpuinfo:\n"); 2240 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2241 st->print(" <Not Available>"); 2242 } 2243 st->cr(); 2244 } 2245 2246 void os::print_siginfo(outputStream* st, void* siginfo) { 2247 const siginfo_t* si = (const siginfo_t*)siginfo; 2248 2249 os::Posix::print_siginfo_brief(st, si); 2250 2251 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2252 UseSharedSpaces) { 2253 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2254 if (mapinfo->is_in_shared_space(si->si_addr)) { 2255 st->print("\n\nError accessing class data sharing archive." \ 2256 " Mapped file inaccessible during execution, " \ 2257 " possible disk/network problem."); 2258 } 2259 } 2260 st->cr(); 2261 } 2262 2263 2264 static void print_signal_handler(outputStream* st, int sig, 2265 char* buf, size_t buflen); 2266 2267 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2268 st->print_cr("Signal Handlers:"); 2269 print_signal_handler(st, SIGSEGV, buf, buflen); 2270 print_signal_handler(st, SIGBUS , buf, buflen); 2271 print_signal_handler(st, SIGFPE , buf, buflen); 2272 print_signal_handler(st, SIGPIPE, buf, buflen); 2273 print_signal_handler(st, SIGXFSZ, buf, buflen); 2274 print_signal_handler(st, SIGILL , buf, buflen); 2275 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2276 print_signal_handler(st, SR_signum, buf, buflen); 2277 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2278 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2279 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2280 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2281 #if defined(PPC64) 2282 print_signal_handler(st, SIGTRAP, buf, buflen); 2283 #endif 2284 } 2285 2286 static char saved_jvm_path[MAXPATHLEN] = {0}; 2287 2288 // Find the full path to the current module, libjvm.so 2289 void os::jvm_path(char *buf, jint buflen) { 2290 // Error checking. 2291 if (buflen < MAXPATHLEN) { 2292 assert(false, "must use a large-enough buffer"); 2293 buf[0] = '\0'; 2294 return; 2295 } 2296 // Lazy resolve the path to current module. 2297 if (saved_jvm_path[0] != 0) { 2298 strcpy(buf, saved_jvm_path); 2299 return; 2300 } 2301 2302 char dli_fname[MAXPATHLEN]; 2303 bool ret = dll_address_to_library_name( 2304 CAST_FROM_FN_PTR(address, os::jvm_path), 2305 dli_fname, sizeof(dli_fname), NULL); 2306 assert(ret, "cannot locate libjvm"); 2307 char *rp = NULL; 2308 if (ret && dli_fname[0] != '\0') { 2309 rp = realpath(dli_fname, buf); 2310 } 2311 if (rp == NULL) 2312 return; 2313 2314 if (Arguments::sun_java_launcher_is_altjvm()) { 2315 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical 2316 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". 2317 // If "/jre/lib/" appears at the right place in the string, then 2318 // assume we are installed in a JDK and we're done. Otherwise, check 2319 // for a JAVA_HOME environment variable and fix up the path so it 2320 // looks like libjvm.so is installed there (append a fake suffix 2321 // hotspot/libjvm.so). 2322 const char *p = buf + strlen(buf) - 1; 2323 for (int count = 0; p > buf && count < 5; ++count) { 2324 for (--p; p > buf && *p != '/'; --p) 2325 /* empty */ ; 2326 } 2327 2328 if (strncmp(p, "/jre/lib/", 9) != 0) { 2329 // Look for JAVA_HOME in the environment. 2330 char* java_home_var = ::getenv("JAVA_HOME"); 2331 if (java_home_var != NULL && java_home_var[0] != 0) { 2332 char* jrelib_p; 2333 int len; 2334 2335 // Check the current module name "libjvm.so". 2336 p = strrchr(buf, '/'); 2337 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2338 2339 rp = realpath(java_home_var, buf); 2340 if (rp == NULL) 2341 return; 2342 2343 // determine if this is a legacy image or modules image 2344 // modules image doesn't have "jre" subdirectory 2345 len = strlen(buf); 2346 jrelib_p = buf + len; 2347 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2348 if (0 != access(buf, F_OK)) { 2349 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2350 } 2351 2352 if (0 == access(buf, F_OK)) { 2353 // Use current module name "libjvm.so" 2354 len = strlen(buf); 2355 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2356 } else { 2357 // Go back to path of .so 2358 rp = realpath(dli_fname, buf); 2359 if (rp == NULL) 2360 return; 2361 } 2362 } 2363 } 2364 } 2365 2366 strcpy(saved_jvm_path, buf); 2367 } 2368 2369 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2370 // no prefix required, not even "_" 2371 } 2372 2373 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2374 // no suffix required 2375 } 2376 2377 //////////////////////////////////////////////////////////////////////////////// 2378 // sun.misc.Signal support 2379 2380 static volatile jint sigint_count = 0; 2381 2382 static void 2383 UserHandler(int sig, void *siginfo, void *context) { 2384 // 4511530 - sem_post is serialized and handled by the manager thread. When 2385 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2386 // don't want to flood the manager thread with sem_post requests. 2387 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2388 return; 2389 2390 // Ctrl-C is pressed during error reporting, likely because the error 2391 // handler fails to abort. Let VM die immediately. 2392 if (sig == SIGINT && is_error_reported()) { 2393 os::die(); 2394 } 2395 2396 os::signal_notify(sig); 2397 } 2398 2399 void* os::user_handler() { 2400 return CAST_FROM_FN_PTR(void*, UserHandler); 2401 } 2402 2403 class Semaphore : public StackObj { 2404 public: 2405 Semaphore(); 2406 ~Semaphore(); 2407 void signal(); 2408 void wait(); 2409 bool trywait(); 2410 bool timedwait(unsigned int sec, int nsec); 2411 private: 2412 sem_t _semaphore; 2413 }; 2414 2415 Semaphore::Semaphore() { 2416 sem_init(&_semaphore, 0, 0); 2417 } 2418 2419 Semaphore::~Semaphore() { 2420 sem_destroy(&_semaphore); 2421 } 2422 2423 void Semaphore::signal() { 2424 sem_post(&_semaphore); 2425 } 2426 2427 void Semaphore::wait() { 2428 sem_wait(&_semaphore); 2429 } 2430 2431 bool Semaphore::trywait() { 2432 return sem_trywait(&_semaphore) == 0; 2433 } 2434 2435 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2436 2437 struct timespec ts; 2438 // Semaphore's are always associated with CLOCK_REALTIME 2439 os::Linux::clock_gettime(CLOCK_REALTIME, &ts); 2440 // see unpackTime for discussion on overflow checking 2441 if (sec >= MAX_SECS) { 2442 ts.tv_sec += MAX_SECS; 2443 ts.tv_nsec = 0; 2444 } else { 2445 ts.tv_sec += sec; 2446 ts.tv_nsec += nsec; 2447 if (ts.tv_nsec >= NANOSECS_PER_SEC) { 2448 ts.tv_nsec -= NANOSECS_PER_SEC; 2449 ++ts.tv_sec; // note: this must be <= max_secs 2450 } 2451 } 2452 2453 while (1) { 2454 int result = sem_timedwait(&_semaphore, &ts); 2455 if (result == 0) { 2456 return true; 2457 } else if (errno == EINTR) { 2458 continue; 2459 } else if (errno == ETIMEDOUT) { 2460 return false; 2461 } else { 2462 return false; 2463 } 2464 } 2465 } 2466 2467 extern "C" { 2468 typedef void (*sa_handler_t)(int); 2469 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2470 } 2471 2472 void* os::signal(int signal_number, void* handler) { 2473 struct sigaction sigAct, oldSigAct; 2474 2475 sigfillset(&(sigAct.sa_mask)); 2476 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2477 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2478 2479 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2480 // -1 means registration failed 2481 return (void *)-1; 2482 } 2483 2484 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2485 } 2486 2487 void os::signal_raise(int signal_number) { 2488 ::raise(signal_number); 2489 } 2490 2491 /* 2492 * The following code is moved from os.cpp for making this 2493 * code platform specific, which it is by its very nature. 2494 */ 2495 2496 // Will be modified when max signal is changed to be dynamic 2497 int os::sigexitnum_pd() { 2498 return NSIG; 2499 } 2500 2501 // a counter for each possible signal value 2502 static volatile jint pending_signals[NSIG+1] = { 0 }; 2503 2504 // Linux(POSIX) specific hand shaking semaphore. 2505 static sem_t sig_sem; 2506 static Semaphore sr_semaphore; 2507 2508 void os::signal_init_pd() { 2509 // Initialize signal structures 2510 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2511 2512 // Initialize signal semaphore 2513 ::sem_init(&sig_sem, 0, 0); 2514 } 2515 2516 void os::signal_notify(int sig) { 2517 Atomic::inc(&pending_signals[sig]); 2518 ::sem_post(&sig_sem); 2519 } 2520 2521 static int check_pending_signals(bool wait) { 2522 Atomic::store(0, &sigint_count); 2523 for (;;) { 2524 for (int i = 0; i < NSIG + 1; i++) { 2525 jint n = pending_signals[i]; 2526 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2527 return i; 2528 } 2529 } 2530 if (!wait) { 2531 return -1; 2532 } 2533 JavaThread *thread = JavaThread::current(); 2534 ThreadBlockInVM tbivm(thread); 2535 2536 bool threadIsSuspended; 2537 do { 2538 thread->set_suspend_equivalent(); 2539 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2540 ::sem_wait(&sig_sem); 2541 2542 // were we externally suspended while we were waiting? 2543 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2544 if (threadIsSuspended) { 2545 // 2546 // The semaphore has been incremented, but while we were waiting 2547 // another thread suspended us. We don't want to continue running 2548 // while suspended because that would surprise the thread that 2549 // suspended us. 2550 // 2551 ::sem_post(&sig_sem); 2552 2553 thread->java_suspend_self(); 2554 } 2555 } while (threadIsSuspended); 2556 } 2557 } 2558 2559 int os::signal_lookup() { 2560 return check_pending_signals(false); 2561 } 2562 2563 int os::signal_wait() { 2564 return check_pending_signals(true); 2565 } 2566 2567 //////////////////////////////////////////////////////////////////////////////// 2568 // Virtual Memory 2569 2570 int os::vm_page_size() { 2571 // Seems redundant as all get out 2572 assert(os::Linux::page_size() != -1, "must call os::init"); 2573 return os::Linux::page_size(); 2574 } 2575 2576 // Solaris allocates memory by pages. 2577 int os::vm_allocation_granularity() { 2578 assert(os::Linux::page_size() != -1, "must call os::init"); 2579 return os::Linux::page_size(); 2580 } 2581 2582 // Rationale behind this function: 2583 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2584 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2585 // samples for JITted code. Here we create private executable mapping over the code cache 2586 // and then we can use standard (well, almost, as mapping can change) way to provide 2587 // info for the reporting script by storing timestamp and location of symbol 2588 void linux_wrap_code(char* base, size_t size) { 2589 static volatile jint cnt = 0; 2590 2591 if (!UseOprofile) { 2592 return; 2593 } 2594 2595 char buf[PATH_MAX+1]; 2596 int num = Atomic::add(1, &cnt); 2597 2598 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2599 os::get_temp_directory(), os::current_process_id(), num); 2600 unlink(buf); 2601 2602 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2603 2604 if (fd != -1) { 2605 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2606 if (rv != (off_t)-1) { 2607 if (::write(fd, "", 1) == 1) { 2608 mmap(base, size, 2609 PROT_READ|PROT_WRITE|PROT_EXEC, 2610 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2611 } 2612 } 2613 ::close(fd); 2614 unlink(buf); 2615 } 2616 } 2617 2618 static bool recoverable_mmap_error(int err) { 2619 // See if the error is one we can let the caller handle. This 2620 // list of errno values comes from JBS-6843484. I can't find a 2621 // Linux man page that documents this specific set of errno 2622 // values so while this list currently matches Solaris, it may 2623 // change as we gain experience with this failure mode. 2624 switch (err) { 2625 case EBADF: 2626 case EINVAL: 2627 case ENOTSUP: 2628 // let the caller deal with these errors 2629 return true; 2630 2631 default: 2632 // Any remaining errors on this OS can cause our reserved mapping 2633 // to be lost. That can cause confusion where different data 2634 // structures think they have the same memory mapped. The worst 2635 // scenario is if both the VM and a library think they have the 2636 // same memory mapped. 2637 return false; 2638 } 2639 } 2640 2641 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2642 int err) { 2643 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2644 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2645 strerror(err), err); 2646 } 2647 2648 static void warn_fail_commit_memory(char* addr, size_t size, 2649 size_t alignment_hint, bool exec, 2650 int err) { 2651 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2652 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2653 alignment_hint, exec, strerror(err), err); 2654 } 2655 2656 // NOTE: Linux kernel does not really reserve the pages for us. 2657 // All it does is to check if there are enough free pages 2658 // left at the time of mmap(). This could be a potential 2659 // problem. 2660 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2661 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2662 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2663 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2664 if (res != (uintptr_t) MAP_FAILED) { 2665 if (UseNUMAInterleaving) { 2666 numa_make_global(addr, size); 2667 } 2668 return 0; 2669 } 2670 2671 int err = errno; // save errno from mmap() call above 2672 2673 if (!recoverable_mmap_error(err)) { 2674 warn_fail_commit_memory(addr, size, exec, err); 2675 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2676 } 2677 2678 return err; 2679 } 2680 2681 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2682 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2683 } 2684 2685 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2686 const char* mesg) { 2687 assert(mesg != NULL, "mesg must be specified"); 2688 int err = os::Linux::commit_memory_impl(addr, size, exec); 2689 if (err != 0) { 2690 // the caller wants all commit errors to exit with the specified mesg: 2691 warn_fail_commit_memory(addr, size, exec, err); 2692 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2693 } 2694 } 2695 2696 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2697 #ifndef MAP_HUGETLB 2698 #define MAP_HUGETLB 0x40000 2699 #endif 2700 2701 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2702 #ifndef MADV_HUGEPAGE 2703 #define MADV_HUGEPAGE 14 2704 #endif 2705 2706 int os::Linux::commit_memory_impl(char* addr, size_t size, 2707 size_t alignment_hint, bool exec) { 2708 int err = os::Linux::commit_memory_impl(addr, size, exec); 2709 if (err == 0) { 2710 realign_memory(addr, size, alignment_hint); 2711 } 2712 return err; 2713 } 2714 2715 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2716 bool exec) { 2717 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2718 } 2719 2720 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2721 size_t alignment_hint, bool exec, 2722 const char* mesg) { 2723 assert(mesg != NULL, "mesg must be specified"); 2724 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2725 if (err != 0) { 2726 // the caller wants all commit errors to exit with the specified mesg: 2727 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2728 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2729 } 2730 } 2731 2732 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2733 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2734 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2735 // be supported or the memory may already be backed by huge pages. 2736 ::madvise(addr, bytes, MADV_HUGEPAGE); 2737 } 2738 } 2739 2740 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2741 // This method works by doing an mmap over an existing mmaping and effectively discarding 2742 // the existing pages. However it won't work for SHM-based large pages that cannot be 2743 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2744 // small pages on top of the SHM segment. This method always works for small pages, so we 2745 // allow that in any case. 2746 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2747 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2748 } 2749 } 2750 2751 void os::numa_make_global(char *addr, size_t bytes) { 2752 Linux::numa_interleave_memory(addr, bytes); 2753 } 2754 2755 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2756 // bind policy to MPOL_PREFERRED for the current thread. 2757 #define USE_MPOL_PREFERRED 0 2758 2759 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2760 // To make NUMA and large pages more robust when both enabled, we need to ease 2761 // the requirements on where the memory should be allocated. MPOL_BIND is the 2762 // default policy and it will force memory to be allocated on the specified 2763 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2764 // the specified node, but will not force it. Using this policy will prevent 2765 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2766 // free large pages. 2767 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2768 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2769 } 2770 2771 bool os::numa_topology_changed() { return false; } 2772 2773 size_t os::numa_get_groups_num() { 2774 int max_node = Linux::numa_max_node(); 2775 return max_node > 0 ? max_node + 1 : 1; 2776 } 2777 2778 int os::numa_get_group_id() { 2779 int cpu_id = Linux::sched_getcpu(); 2780 if (cpu_id != -1) { 2781 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2782 if (lgrp_id != -1) { 2783 return lgrp_id; 2784 } 2785 } 2786 return 0; 2787 } 2788 2789 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2790 for (size_t i = 0; i < size; i++) { 2791 ids[i] = i; 2792 } 2793 return size; 2794 } 2795 2796 bool os::get_page_info(char *start, page_info* info) { 2797 return false; 2798 } 2799 2800 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2801 return end; 2802 } 2803 2804 2805 int os::Linux::sched_getcpu_syscall(void) { 2806 unsigned int cpu; 2807 int retval = -1; 2808 2809 #if defined(IA32) 2810 # ifndef SYS_getcpu 2811 # define SYS_getcpu 318 2812 # endif 2813 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2814 #elif defined(AMD64) 2815 // Unfortunately we have to bring all these macros here from vsyscall.h 2816 // to be able to compile on old linuxes. 2817 # define __NR_vgetcpu 2 2818 # define VSYSCALL_START (-10UL << 20) 2819 # define VSYSCALL_SIZE 1024 2820 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2821 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2822 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2823 retval = vgetcpu(&cpu, NULL, NULL); 2824 #endif 2825 2826 return (retval == -1) ? retval : cpu; 2827 } 2828 2829 // Something to do with the numa-aware allocator needs these symbols 2830 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2831 extern "C" JNIEXPORT void numa_error(char *where) { } 2832 extern "C" JNIEXPORT int fork1() { return fork(); } 2833 2834 2835 // If we are running with libnuma version > 2, then we should 2836 // be trying to use symbols with versions 1.1 2837 // If we are running with earlier version, which did not have symbol versions, 2838 // we should use the base version. 2839 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2840 void *f = dlvsym(handle, name, "libnuma_1.1"); 2841 if (f == NULL) { 2842 f = dlsym(handle, name); 2843 } 2844 return f; 2845 } 2846 2847 bool os::Linux::libnuma_init() { 2848 // sched_getcpu() should be in libc. 2849 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2850 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2851 2852 // If it's not, try a direct syscall. 2853 if (sched_getcpu() == -1) 2854 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall)); 2855 2856 if (sched_getcpu() != -1) { // Does it work? 2857 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2858 if (handle != NULL) { 2859 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2860 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2861 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2862 libnuma_dlsym(handle, "numa_max_node"))); 2863 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2864 libnuma_dlsym(handle, "numa_available"))); 2865 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2866 libnuma_dlsym(handle, "numa_tonode_memory"))); 2867 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2868 libnuma_dlsym(handle, "numa_interleave_memory"))); 2869 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2870 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2871 2872 2873 if (numa_available() != -1) { 2874 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2875 // Create a cpu -> node mapping 2876 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2877 rebuild_cpu_to_node_map(); 2878 return true; 2879 } 2880 } 2881 } 2882 return false; 2883 } 2884 2885 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2886 // The table is later used in get_node_by_cpu(). 2887 void os::Linux::rebuild_cpu_to_node_map() { 2888 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2889 // in libnuma (possible values are starting from 16, 2890 // and continuing up with every other power of 2, but less 2891 // than the maximum number of CPUs supported by kernel), and 2892 // is a subject to change (in libnuma version 2 the requirements 2893 // are more reasonable) we'll just hardcode the number they use 2894 // in the library. 2895 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2896 2897 size_t cpu_num = os::active_processor_count(); 2898 size_t cpu_map_size = NCPUS / BitsPerCLong; 2899 size_t cpu_map_valid_size = 2900 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2901 2902 cpu_to_node()->clear(); 2903 cpu_to_node()->at_grow(cpu_num - 1); 2904 size_t node_num = numa_get_groups_num(); 2905 2906 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2907 for (size_t i = 0; i < node_num; i++) { 2908 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2909 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2910 if (cpu_map[j] != 0) { 2911 for (size_t k = 0; k < BitsPerCLong; k++) { 2912 if (cpu_map[j] & (1UL << k)) { 2913 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2914 } 2915 } 2916 } 2917 } 2918 } 2919 } 2920 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal); 2921 } 2922 2923 int os::Linux::get_node_by_cpu(int cpu_id) { 2924 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2925 return cpu_to_node()->at(cpu_id); 2926 } 2927 return -1; 2928 } 2929 2930 GrowableArray<int>* os::Linux::_cpu_to_node; 2931 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2932 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2933 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2934 os::Linux::numa_available_func_t os::Linux::_numa_available; 2935 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2936 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2937 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2938 unsigned long* os::Linux::_numa_all_nodes; 2939 2940 bool os::pd_uncommit_memory(char* addr, size_t size) { 2941 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2942 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2943 return res != (uintptr_t) MAP_FAILED; 2944 } 2945 2946 static 2947 address get_stack_commited_bottom(address bottom, size_t size) { 2948 address nbot = bottom; 2949 address ntop = bottom + size; 2950 2951 size_t page_sz = os::vm_page_size(); 2952 unsigned pages = size / page_sz; 2953 2954 unsigned char vec[1]; 2955 unsigned imin = 1, imax = pages + 1, imid; 2956 int mincore_return_value = 0; 2957 2958 assert(imin <= imax, "Unexpected page size"); 2959 2960 while (imin < imax) { 2961 imid = (imax + imin) / 2; 2962 nbot = ntop - (imid * page_sz); 2963 2964 // Use a trick with mincore to check whether the page is mapped or not. 2965 // mincore sets vec to 1 if page resides in memory and to 0 if page 2966 // is swapped output but if page we are asking for is unmapped 2967 // it returns -1,ENOMEM 2968 mincore_return_value = mincore(nbot, page_sz, vec); 2969 2970 if (mincore_return_value == -1) { 2971 // Page is not mapped go up 2972 // to find first mapped page 2973 if (errno != EAGAIN) { 2974 assert(errno == ENOMEM, "Unexpected mincore errno"); 2975 imax = imid; 2976 } 2977 } else { 2978 // Page is mapped go down 2979 // to find first not mapped page 2980 imin = imid + 1; 2981 } 2982 } 2983 2984 nbot = nbot + page_sz; 2985 2986 // Adjust stack bottom one page up if last checked page is not mapped 2987 if (mincore_return_value == -1) { 2988 nbot = nbot + page_sz; 2989 } 2990 2991 return nbot; 2992 } 2993 2994 2995 // Linux uses a growable mapping for the stack, and if the mapping for 2996 // the stack guard pages is not removed when we detach a thread the 2997 // stack cannot grow beyond the pages where the stack guard was 2998 // mapped. If at some point later in the process the stack expands to 2999 // that point, the Linux kernel cannot expand the stack any further 3000 // because the guard pages are in the way, and a segfault occurs. 3001 // 3002 // However, it's essential not to split the stack region by unmapping 3003 // a region (leaving a hole) that's already part of the stack mapping, 3004 // so if the stack mapping has already grown beyond the guard pages at 3005 // the time we create them, we have to truncate the stack mapping. 3006 // So, we need to know the extent of the stack mapping when 3007 // create_stack_guard_pages() is called. 3008 3009 // We only need this for stacks that are growable: at the time of 3010 // writing thread stacks don't use growable mappings (i.e. those 3011 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 3012 // only applies to the main thread. 3013 3014 // If the (growable) stack mapping already extends beyond the point 3015 // where we're going to put our guard pages, truncate the mapping at 3016 // that point by munmap()ping it. This ensures that when we later 3017 // munmap() the guard pages we don't leave a hole in the stack 3018 // mapping. This only affects the main/initial thread 3019 3020 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3021 3022 if (os::Linux::is_initial_thread()) { 3023 // As we manually grow stack up to bottom inside create_attached_thread(), 3024 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3025 // we don't need to do anything special. 3026 // Check it first, before calling heavy function. 3027 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3028 unsigned char vec[1]; 3029 3030 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3031 // Fallback to slow path on all errors, including EAGAIN 3032 stack_extent = (uintptr_t) get_stack_commited_bottom( 3033 os::Linux::initial_thread_stack_bottom(), 3034 (size_t)addr - stack_extent); 3035 } 3036 3037 if (stack_extent < (uintptr_t)addr) { 3038 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3039 } 3040 } 3041 3042 return os::commit_memory(addr, size, !ExecMem); 3043 } 3044 3045 // If this is a growable mapping, remove the guard pages entirely by 3046 // munmap()ping them. If not, just call uncommit_memory(). This only 3047 // affects the main/initial thread, but guard against future OS changes 3048 // It's safe to always unmap guard pages for initial thread because we 3049 // always place it right after end of the mapped region 3050 3051 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3052 uintptr_t stack_extent, stack_base; 3053 3054 if (os::Linux::is_initial_thread()) { 3055 return ::munmap(addr, size) == 0; 3056 } 3057 3058 return os::uncommit_memory(addr, size); 3059 } 3060 3061 static address _highest_vm_reserved_address = NULL; 3062 3063 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3064 // at 'requested_addr'. If there are existing memory mappings at the same 3065 // location, however, they will be overwritten. If 'fixed' is false, 3066 // 'requested_addr' is only treated as a hint, the return value may or 3067 // may not start from the requested address. Unlike Linux mmap(), this 3068 // function returns NULL to indicate failure. 3069 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3070 char * addr; 3071 int flags; 3072 3073 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3074 if (fixed) { 3075 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3076 flags |= MAP_FIXED; 3077 } 3078 3079 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3080 // touch an uncommitted page. Otherwise, the read/write might 3081 // succeed if we have enough swap space to back the physical page. 3082 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3083 flags, -1, 0); 3084 3085 if (addr != MAP_FAILED) { 3086 // anon_mmap() should only get called during VM initialization, 3087 // don't need lock (actually we can skip locking even it can be called 3088 // from multiple threads, because _highest_vm_reserved_address is just a 3089 // hint about the upper limit of non-stack memory regions.) 3090 if ((address)addr + bytes > _highest_vm_reserved_address) { 3091 _highest_vm_reserved_address = (address)addr + bytes; 3092 } 3093 } 3094 3095 return addr == MAP_FAILED ? NULL : addr; 3096 } 3097 3098 // Don't update _highest_vm_reserved_address, because there might be memory 3099 // regions above addr + size. If so, releasing a memory region only creates 3100 // a hole in the address space, it doesn't help prevent heap-stack collision. 3101 // 3102 static int anon_munmap(char * addr, size_t size) { 3103 return ::munmap(addr, size) == 0; 3104 } 3105 3106 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3107 size_t alignment_hint) { 3108 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3109 } 3110 3111 bool os::pd_release_memory(char* addr, size_t size) { 3112 return anon_munmap(addr, size); 3113 } 3114 3115 static address highest_vm_reserved_address() { 3116 return _highest_vm_reserved_address; 3117 } 3118 3119 static bool linux_mprotect(char* addr, size_t size, int prot) { 3120 // Linux wants the mprotect address argument to be page aligned. 3121 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3122 3123 // According to SUSv3, mprotect() should only be used with mappings 3124 // established by mmap(), and mmap() always maps whole pages. Unaligned 3125 // 'addr' likely indicates problem in the VM (e.g. trying to change 3126 // protection of malloc'ed or statically allocated memory). Check the 3127 // caller if you hit this assert. 3128 assert(addr == bottom, "sanity check"); 3129 3130 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3131 return ::mprotect(bottom, size, prot) == 0; 3132 } 3133 3134 // Set protections specified 3135 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3136 bool is_committed) { 3137 unsigned int p = 0; 3138 switch (prot) { 3139 case MEM_PROT_NONE: p = PROT_NONE; break; 3140 case MEM_PROT_READ: p = PROT_READ; break; 3141 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3142 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3143 default: 3144 ShouldNotReachHere(); 3145 } 3146 // is_committed is unused. 3147 return linux_mprotect(addr, bytes, p); 3148 } 3149 3150 bool os::guard_memory(char* addr, size_t size) { 3151 return linux_mprotect(addr, size, PROT_NONE); 3152 } 3153 3154 bool os::unguard_memory(char* addr, size_t size) { 3155 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3156 } 3157 3158 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) { 3159 bool result = false; 3160 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3161 MAP_ANONYMOUS|MAP_PRIVATE, 3162 -1, 0); 3163 if (p != MAP_FAILED) { 3164 void *aligned_p = align_ptr_up(p, page_size); 3165 3166 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3167 3168 munmap(p, page_size * 2); 3169 } 3170 3171 if (warn && !result) { 3172 warning("TransparentHugePages is not supported by the operating system."); 3173 } 3174 3175 return result; 3176 } 3177 3178 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3179 bool result = false; 3180 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3181 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3182 -1, 0); 3183 3184 if (p != MAP_FAILED) { 3185 // We don't know if this really is a huge page or not. 3186 FILE *fp = fopen("/proc/self/maps", "r"); 3187 if (fp) { 3188 while (!feof(fp)) { 3189 char chars[257]; 3190 long x = 0; 3191 if (fgets(chars, sizeof(chars), fp)) { 3192 if (sscanf(chars, "%lx-%*x", &x) == 1 3193 && x == (long)p) { 3194 if (strstr (chars, "hugepage")) { 3195 result = true; 3196 break; 3197 } 3198 } 3199 } 3200 } 3201 fclose(fp); 3202 } 3203 munmap(p, page_size); 3204 } 3205 3206 if (warn && !result) { 3207 warning("HugeTLBFS is not supported by the operating system."); 3208 } 3209 3210 return result; 3211 } 3212 3213 /* 3214 * Set the coredump_filter bits to include largepages in core dump (bit 6) 3215 * 3216 * From the coredump_filter documentation: 3217 * 3218 * - (bit 0) anonymous private memory 3219 * - (bit 1) anonymous shared memory 3220 * - (bit 2) file-backed private memory 3221 * - (bit 3) file-backed shared memory 3222 * - (bit 4) ELF header pages in file-backed private memory areas (it is 3223 * effective only if the bit 2 is cleared) 3224 * - (bit 5) hugetlb private memory 3225 * - (bit 6) hugetlb shared memory 3226 */ 3227 static void set_coredump_filter(void) { 3228 FILE *f; 3229 long cdm; 3230 3231 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3232 return; 3233 } 3234 3235 if (fscanf(f, "%lx", &cdm) != 1) { 3236 fclose(f); 3237 return; 3238 } 3239 3240 rewind(f); 3241 3242 if ((cdm & LARGEPAGES_BIT) == 0) { 3243 cdm |= LARGEPAGES_BIT; 3244 fprintf(f, "%#lx", cdm); 3245 } 3246 3247 fclose(f); 3248 } 3249 3250 // Large page support 3251 3252 static size_t _large_page_size = 0; 3253 3254 size_t os::Linux::find_large_page_size() { 3255 size_t large_page_size = 0; 3256 3257 // large_page_size on Linux is used to round up heap size. x86 uses either 3258 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3259 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3260 // page as large as 256M. 3261 // 3262 // Here we try to figure out page size by parsing /proc/meminfo and looking 3263 // for a line with the following format: 3264 // Hugepagesize: 2048 kB 3265 // 3266 // If we can't determine the value (e.g. /proc is not mounted, or the text 3267 // format has been changed), we'll use the largest page size supported by 3268 // the processor. 3269 3270 #ifndef ZERO 3271 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3272 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3273 #endif // ZERO 3274 3275 FILE *fp = fopen("/proc/meminfo", "r"); 3276 if (fp) { 3277 while (!feof(fp)) { 3278 int x = 0; 3279 char buf[16]; 3280 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3281 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3282 large_page_size = x * K; 3283 break; 3284 } 3285 } else { 3286 // skip to next line 3287 for (;;) { 3288 int ch = fgetc(fp); 3289 if (ch == EOF || ch == (int)'\n') break; 3290 } 3291 } 3292 } 3293 fclose(fp); 3294 } 3295 3296 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3297 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3298 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3299 proper_unit_for_byte_size(large_page_size)); 3300 } 3301 3302 return large_page_size; 3303 } 3304 3305 size_t os::Linux::setup_large_page_size() { 3306 _large_page_size = Linux::find_large_page_size(); 3307 const size_t default_page_size = (size_t)Linux::page_size(); 3308 if (_large_page_size > default_page_size) { 3309 _page_sizes[0] = _large_page_size; 3310 _page_sizes[1] = default_page_size; 3311 _page_sizes[2] = 0; 3312 } 3313 3314 return _large_page_size; 3315 } 3316 3317 bool os::Linux::setup_large_page_type(size_t page_size) { 3318 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3319 FLAG_IS_DEFAULT(UseSHM) && 3320 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3321 3322 // The type of large pages has not been specified by the user. 3323 3324 // Try UseHugeTLBFS and then UseSHM. 3325 UseHugeTLBFS = UseSHM = true; 3326 3327 // Don't try UseTransparentHugePages since there are known 3328 // performance issues with it turned on. This might change in the future. 3329 UseTransparentHugePages = false; 3330 } 3331 3332 if (UseTransparentHugePages) { 3333 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3334 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3335 UseHugeTLBFS = false; 3336 UseSHM = false; 3337 return true; 3338 } 3339 UseTransparentHugePages = false; 3340 } 3341 3342 if (UseHugeTLBFS) { 3343 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3344 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3345 UseSHM = false; 3346 return true; 3347 } 3348 UseHugeTLBFS = false; 3349 } 3350 3351 return UseSHM; 3352 } 3353 3354 void os::large_page_init() { 3355 if (!UseLargePages && 3356 !UseTransparentHugePages && 3357 !UseHugeTLBFS && 3358 !UseSHM) { 3359 // Not using large pages. 3360 return; 3361 } 3362 3363 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3364 // The user explicitly turned off large pages. 3365 // Ignore the rest of the large pages flags. 3366 UseTransparentHugePages = false; 3367 UseHugeTLBFS = false; 3368 UseSHM = false; 3369 return; 3370 } 3371 3372 size_t large_page_size = Linux::setup_large_page_size(); 3373 UseLargePages = Linux::setup_large_page_type(large_page_size); 3374 3375 set_coredump_filter(); 3376 } 3377 3378 #ifndef SHM_HUGETLB 3379 #define SHM_HUGETLB 04000 3380 #endif 3381 3382 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3383 // "exec" is passed in but not used. Creating the shared image for 3384 // the code cache doesn't have an SHM_X executable permission to check. 3385 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3386 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3387 3388 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3389 return NULL; // Fallback to small pages. 3390 } 3391 3392 key_t key = IPC_PRIVATE; 3393 char *addr; 3394 3395 bool warn_on_failure = UseLargePages && 3396 (!FLAG_IS_DEFAULT(UseLargePages) || 3397 !FLAG_IS_DEFAULT(UseSHM) || 3398 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 3399 ); 3400 char msg[128]; 3401 3402 // Create a large shared memory region to attach to based on size. 3403 // Currently, size is the total size of the heap 3404 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3405 if (shmid == -1) { 3406 // Possible reasons for shmget failure: 3407 // 1. shmmax is too small for Java heap. 3408 // > check shmmax value: cat /proc/sys/kernel/shmmax 3409 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3410 // 2. not enough large page memory. 3411 // > check available large pages: cat /proc/meminfo 3412 // > increase amount of large pages: 3413 // echo new_value > /proc/sys/vm/nr_hugepages 3414 // Note 1: different Linux may use different name for this property, 3415 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3416 // Note 2: it's possible there's enough physical memory available but 3417 // they are so fragmented after a long run that they can't 3418 // coalesce into large pages. Try to reserve large pages when 3419 // the system is still "fresh". 3420 if (warn_on_failure) { 3421 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3422 warning("%s", msg); 3423 } 3424 return NULL; 3425 } 3426 3427 // attach to the region 3428 addr = (char*)shmat(shmid, req_addr, 0); 3429 int err = errno; 3430 3431 // Remove shmid. If shmat() is successful, the actual shared memory segment 3432 // will be deleted when it's detached by shmdt() or when the process 3433 // terminates. If shmat() is not successful this will remove the shared 3434 // segment immediately. 3435 shmctl(shmid, IPC_RMID, NULL); 3436 3437 if ((intptr_t)addr == -1) { 3438 if (warn_on_failure) { 3439 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3440 warning("%s", msg); 3441 } 3442 return NULL; 3443 } 3444 3445 return addr; 3446 } 3447 3448 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) { 3449 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3450 3451 bool warn_on_failure = UseLargePages && 3452 (!FLAG_IS_DEFAULT(UseLargePages) || 3453 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3454 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3455 3456 if (warn_on_failure) { 3457 char msg[128]; 3458 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3459 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3460 warning("%s", msg); 3461 } 3462 } 3463 3464 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) { 3465 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3466 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3467 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3468 3469 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3470 char* addr = (char*)::mmap(req_addr, bytes, prot, 3471 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3472 -1, 0); 3473 3474 if (addr == MAP_FAILED) { 3475 warn_on_large_pages_failure(req_addr, bytes, errno); 3476 return NULL; 3477 } 3478 3479 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3480 3481 return addr; 3482 } 3483 3484 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3485 size_t large_page_size = os::large_page_size(); 3486 3487 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3488 3489 // Allocate small pages. 3490 3491 char* start; 3492 if (req_addr != NULL) { 3493 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3494 assert(is_size_aligned(bytes, alignment), "Must be"); 3495 start = os::reserve_memory(bytes, req_addr); 3496 assert(start == NULL || start == req_addr, "Must be"); 3497 } else { 3498 start = os::reserve_memory_aligned(bytes, alignment); 3499 } 3500 3501 if (start == NULL) { 3502 return NULL; 3503 } 3504 3505 assert(is_ptr_aligned(start, alignment), "Must be"); 3506 3507 // os::reserve_memory_special will record this memory area. 3508 // Need to release it here to prevent overlapping reservations. 3509 MemTracker::record_virtual_memory_release((address)start, bytes); 3510 3511 char* end = start + bytes; 3512 3513 // Find the regions of the allocated chunk that can be promoted to large pages. 3514 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3515 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3516 3517 size_t lp_bytes = lp_end - lp_start; 3518 3519 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3520 3521 if (lp_bytes == 0) { 3522 // The mapped region doesn't even span the start and the end of a large page. 3523 // Fall back to allocate a non-special area. 3524 ::munmap(start, end - start); 3525 return NULL; 3526 } 3527 3528 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3529 3530 3531 void* result; 3532 3533 if (start != lp_start) { 3534 result = ::mmap(start, lp_start - start, prot, 3535 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3536 -1, 0); 3537 if (result == MAP_FAILED) { 3538 ::munmap(lp_start, end - lp_start); 3539 return NULL; 3540 } 3541 } 3542 3543 result = ::mmap(lp_start, lp_bytes, prot, 3544 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3545 -1, 0); 3546 if (result == MAP_FAILED) { 3547 warn_on_large_pages_failure(req_addr, bytes, errno); 3548 // If the mmap above fails, the large pages region will be unmapped and we 3549 // have regions before and after with small pages. Release these regions. 3550 // 3551 // | mapped | unmapped | mapped | 3552 // ^ ^ ^ ^ 3553 // start lp_start lp_end end 3554 // 3555 ::munmap(start, lp_start - start); 3556 ::munmap(lp_end, end - lp_end); 3557 return NULL; 3558 } 3559 3560 if (lp_end != end) { 3561 result = ::mmap(lp_end, end - lp_end, prot, 3562 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3563 -1, 0); 3564 if (result == MAP_FAILED) { 3565 ::munmap(start, lp_end - start); 3566 return NULL; 3567 } 3568 } 3569 3570 return start; 3571 } 3572 3573 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3574 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3575 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3576 assert(is_power_of_2(alignment), "Must be"); 3577 assert(is_power_of_2(os::large_page_size()), "Must be"); 3578 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3579 3580 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3581 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3582 } else { 3583 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3584 } 3585 } 3586 3587 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) { 3588 assert(UseLargePages, "only for large pages"); 3589 3590 char* addr; 3591 if (UseSHM) { 3592 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3593 } else { 3594 assert(UseHugeTLBFS, "must be"); 3595 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3596 } 3597 3598 if (addr != NULL) { 3599 if (UseNUMAInterleaving) { 3600 numa_make_global(addr, bytes); 3601 } 3602 3603 // The memory is committed 3604 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, mtNone, CALLER_PC); 3605 } 3606 3607 return addr; 3608 } 3609 3610 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3611 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3612 return shmdt(base) == 0; 3613 } 3614 3615 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3616 return pd_release_memory(base, bytes); 3617 } 3618 3619 bool os::release_memory_special(char* base, size_t bytes) { 3620 assert(UseLargePages, "only for large pages"); 3621 3622 MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3623 3624 bool res; 3625 if (UseSHM) { 3626 res = os::Linux::release_memory_special_shm(base, bytes); 3627 } else { 3628 assert(UseHugeTLBFS, "must be"); 3629 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3630 } 3631 3632 if (res) { 3633 tkr.record((address)base, bytes); 3634 } else { 3635 tkr.discard(); 3636 } 3637 3638 return res; 3639 } 3640 3641 size_t os::large_page_size() { 3642 return _large_page_size; 3643 } 3644 3645 // With SysV SHM the entire memory region must be allocated as shared 3646 // memory. 3647 // HugeTLBFS allows application to commit large page memory on demand. 3648 // However, when committing memory with HugeTLBFS fails, the region 3649 // that was supposed to be committed will lose the old reservation 3650 // and allow other threads to steal that memory region. Because of this 3651 // behavior we can't commit HugeTLBFS memory. 3652 bool os::can_commit_large_page_memory() { 3653 return UseTransparentHugePages; 3654 } 3655 3656 bool os::can_execute_large_page_memory() { 3657 return UseTransparentHugePages || UseHugeTLBFS; 3658 } 3659 3660 // Reserve memory at an arbitrary address, only if that area is 3661 // available (and not reserved for something else). 3662 3663 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3664 const int max_tries = 10; 3665 char* base[max_tries]; 3666 size_t size[max_tries]; 3667 const size_t gap = 0x000000; 3668 3669 // Assert only that the size is a multiple of the page size, since 3670 // that's all that mmap requires, and since that's all we really know 3671 // about at this low abstraction level. If we need higher alignment, 3672 // we can either pass an alignment to this method or verify alignment 3673 // in one of the methods further up the call chain. See bug 5044738. 3674 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3675 3676 // Repeatedly allocate blocks until the block is allocated at the 3677 // right spot. Give up after max_tries. Note that reserve_memory() will 3678 // automatically update _highest_vm_reserved_address if the call is 3679 // successful. The variable tracks the highest memory address every reserved 3680 // by JVM. It is used to detect heap-stack collision if running with 3681 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3682 // space than needed, it could confuse the collision detecting code. To 3683 // solve the problem, save current _highest_vm_reserved_address and 3684 // calculate the correct value before return. 3685 address old_highest = _highest_vm_reserved_address; 3686 3687 // Linux mmap allows caller to pass an address as hint; give it a try first, 3688 // if kernel honors the hint then we can return immediately. 3689 char * addr = anon_mmap(requested_addr, bytes, false); 3690 if (addr == requested_addr) { 3691 return requested_addr; 3692 } 3693 3694 if (addr != NULL) { 3695 // mmap() is successful but it fails to reserve at the requested address 3696 anon_munmap(addr, bytes); 3697 } 3698 3699 int i; 3700 for (i = 0; i < max_tries; ++i) { 3701 base[i] = reserve_memory(bytes); 3702 3703 if (base[i] != NULL) { 3704 // Is this the block we wanted? 3705 if (base[i] == requested_addr) { 3706 size[i] = bytes; 3707 break; 3708 } 3709 3710 // Does this overlap the block we wanted? Give back the overlapped 3711 // parts and try again. 3712 3713 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3714 if (top_overlap >= 0 && top_overlap < bytes) { 3715 unmap_memory(base[i], top_overlap); 3716 base[i] += top_overlap; 3717 size[i] = bytes - top_overlap; 3718 } else { 3719 size_t bottom_overlap = base[i] + bytes - requested_addr; 3720 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3721 unmap_memory(requested_addr, bottom_overlap); 3722 size[i] = bytes - bottom_overlap; 3723 } else { 3724 size[i] = bytes; 3725 } 3726 } 3727 } 3728 } 3729 3730 // Give back the unused reserved pieces. 3731 3732 for (int j = 0; j < i; ++j) { 3733 if (base[j] != NULL) { 3734 unmap_memory(base[j], size[j]); 3735 } 3736 } 3737 3738 if (i < max_tries) { 3739 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3740 return requested_addr; 3741 } else { 3742 _highest_vm_reserved_address = old_highest; 3743 return NULL; 3744 } 3745 } 3746 3747 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3748 return ::read(fd, buf, nBytes); 3749 } 3750 3751 // 3752 // Short sleep, direct OS call. 3753 // 3754 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee 3755 // sched_yield(2) will actually give up the CPU: 3756 // 3757 // * Alone on this pariticular CPU, keeps running. 3758 // * Before the introduction of "skip_buddy" with "compat_yield" disabled 3759 // (pre 2.6.39). 3760 // 3761 // So calling this with 0 is an alternative. 3762 // 3763 void os::naked_short_sleep(jlong ms) { 3764 struct timespec req; 3765 3766 assert(ms < 1000, "Un-interruptable sleep, short time use only"); 3767 req.tv_sec = 0; 3768 if (ms > 0) { 3769 req.tv_nsec = (ms % 1000) * 1000000; 3770 } 3771 else { 3772 req.tv_nsec = 1; 3773 } 3774 3775 nanosleep(&req, NULL); 3776 3777 return; 3778 } 3779 3780 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3781 void os::infinite_sleep() { 3782 while (true) { // sleep forever ... 3783 ::sleep(100); // ... 100 seconds at a time 3784 } 3785 } 3786 3787 // Used to convert frequent JVM_Yield() to nops 3788 bool os::dont_yield() { 3789 return DontYieldALot; 3790 } 3791 3792 void os::yield() { 3793 sched_yield(); 3794 } 3795 3796 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 3797 3798 void os::yield_all() { 3799 // Yields to all threads, including threads with lower priorities 3800 // Threads on Linux are all with same priority. The Solaris style 3801 // os::yield_all() with nanosleep(1ms) is not necessary. 3802 sched_yield(); 3803 } 3804 3805 //////////////////////////////////////////////////////////////////////////////// 3806 // thread priority support 3807 3808 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3809 // only supports dynamic priority, static priority must be zero. For real-time 3810 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3811 // However, for large multi-threaded applications, SCHED_RR is not only slower 3812 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3813 // of 5 runs - Sep 2005). 3814 // 3815 // The following code actually changes the niceness of kernel-thread/LWP. It 3816 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3817 // not the entire user process, and user level threads are 1:1 mapped to kernel 3818 // threads. It has always been the case, but could change in the future. For 3819 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3820 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3821 3822 int os::java_to_os_priority[CriticalPriority + 1] = { 3823 19, // 0 Entry should never be used 3824 3825 4, // 1 MinPriority 3826 3, // 2 3827 2, // 3 3828 3829 1, // 4 3830 0, // 5 NormPriority 3831 -1, // 6 3832 3833 -2, // 7 3834 -3, // 8 3835 -4, // 9 NearMaxPriority 3836 3837 -5, // 10 MaxPriority 3838 3839 -5 // 11 CriticalPriority 3840 }; 3841 3842 static int prio_init() { 3843 if (ThreadPriorityPolicy == 1) { 3844 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3845 // if effective uid is not root. Perhaps, a more elegant way of doing 3846 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3847 if (geteuid() != 0) { 3848 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3849 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3850 } 3851 ThreadPriorityPolicy = 0; 3852 } 3853 } 3854 if (UseCriticalJavaThreadPriority) { 3855 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3856 } 3857 return 0; 3858 } 3859 3860 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3861 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 3862 3863 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3864 return (ret == 0) ? OS_OK : OS_ERR; 3865 } 3866 3867 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3868 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3869 *priority_ptr = java_to_os_priority[NormPriority]; 3870 return OS_OK; 3871 } 3872 3873 errno = 0; 3874 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3875 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3876 } 3877 3878 // Hint to the underlying OS that a task switch would not be good. 3879 // Void return because it's a hint and can fail. 3880 void os::hint_no_preempt() {} 3881 3882 //////////////////////////////////////////////////////////////////////////////// 3883 // suspend/resume support 3884 3885 // the low-level signal-based suspend/resume support is a remnant from the 3886 // old VM-suspension that used to be for java-suspension, safepoints etc, 3887 // within hotspot. Now there is a single use-case for this: 3888 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3889 // that runs in the watcher thread. 3890 // The remaining code is greatly simplified from the more general suspension 3891 // code that used to be used. 3892 // 3893 // The protocol is quite simple: 3894 // - suspend: 3895 // - sends a signal to the target thread 3896 // - polls the suspend state of the osthread using a yield loop 3897 // - target thread signal handler (SR_handler) sets suspend state 3898 // and blocks in sigsuspend until continued 3899 // - resume: 3900 // - sets target osthread state to continue 3901 // - sends signal to end the sigsuspend loop in the SR_handler 3902 // 3903 // Note that the SR_lock plays no role in this suspend/resume protocol. 3904 // 3905 3906 static void resume_clear_context(OSThread *osthread) { 3907 osthread->set_ucontext(NULL); 3908 osthread->set_siginfo(NULL); 3909 } 3910 3911 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 3912 osthread->set_ucontext(context); 3913 osthread->set_siginfo(siginfo); 3914 } 3915 3916 // 3917 // Handler function invoked when a thread's execution is suspended or 3918 // resumed. We have to be careful that only async-safe functions are 3919 // called here (Note: most pthread functions are not async safe and 3920 // should be avoided.) 3921 // 3922 // Note: sigwait() is a more natural fit than sigsuspend() from an 3923 // interface point of view, but sigwait() prevents the signal hander 3924 // from being run. libpthread would get very confused by not having 3925 // its signal handlers run and prevents sigwait()'s use with the 3926 // mutex granting granting signal. 3927 // 3928 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 3929 // 3930 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3931 // Save and restore errno to avoid confusing native code with EINTR 3932 // after sigsuspend. 3933 int old_errno = errno; 3934 3935 Thread* thread = Thread::current(); 3936 OSThread* osthread = thread->osthread(); 3937 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 3938 3939 os::SuspendResume::State current = osthread->sr.state(); 3940 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 3941 suspend_save_context(osthread, siginfo, context); 3942 3943 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 3944 os::SuspendResume::State state = osthread->sr.suspended(); 3945 if (state == os::SuspendResume::SR_SUSPENDED) { 3946 sigset_t suspend_set; // signals for sigsuspend() 3947 3948 // get current set of blocked signals and unblock resume signal 3949 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3950 sigdelset(&suspend_set, SR_signum); 3951 3952 sr_semaphore.signal(); 3953 // wait here until we are resumed 3954 while (1) { 3955 sigsuspend(&suspend_set); 3956 3957 os::SuspendResume::State result = osthread->sr.running(); 3958 if (result == os::SuspendResume::SR_RUNNING) { 3959 sr_semaphore.signal(); 3960 break; 3961 } 3962 } 3963 3964 } else if (state == os::SuspendResume::SR_RUNNING) { 3965 // request was cancelled, continue 3966 } else { 3967 ShouldNotReachHere(); 3968 } 3969 3970 resume_clear_context(osthread); 3971 } else if (current == os::SuspendResume::SR_RUNNING) { 3972 // request was cancelled, continue 3973 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 3974 // ignore 3975 } else { 3976 // ignore 3977 } 3978 3979 errno = old_errno; 3980 } 3981 3982 3983 static int SR_initialize() { 3984 struct sigaction act; 3985 char *s; 3986 /* Get signal number to use for suspend/resume */ 3987 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 3988 int sig = ::strtol(s, 0, 10); 3989 if (sig > 0 || sig < _NSIG) { 3990 SR_signum = sig; 3991 } 3992 } 3993 3994 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 3995 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 3996 3997 sigemptyset(&SR_sigset); 3998 sigaddset(&SR_sigset, SR_signum); 3999 4000 /* Set up signal handler for suspend/resume */ 4001 act.sa_flags = SA_RESTART|SA_SIGINFO; 4002 act.sa_handler = (void (*)(int)) SR_handler; 4003 4004 // SR_signum is blocked by default. 4005 // 4528190 - We also need to block pthread restart signal (32 on all 4006 // supported Linux platforms). Note that LinuxThreads need to block 4007 // this signal for all threads to work properly. So we don't have 4008 // to use hard-coded signal number when setting up the mask. 4009 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4010 4011 if (sigaction(SR_signum, &act, 0) == -1) { 4012 return -1; 4013 } 4014 4015 // Save signal flag 4016 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4017 return 0; 4018 } 4019 4020 static int sr_notify(OSThread* osthread) { 4021 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4022 assert_status(status == 0, status, "pthread_kill"); 4023 return status; 4024 } 4025 4026 // "Randomly" selected value for how long we want to spin 4027 // before bailing out on suspending a thread, also how often 4028 // we send a signal to a thread we want to resume 4029 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4030 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4031 4032 // returns true on success and false on error - really an error is fatal 4033 // but this seems the normal response to library errors 4034 static bool do_suspend(OSThread* osthread) { 4035 assert(osthread->sr.is_running(), "thread should be running"); 4036 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4037 4038 // mark as suspended and send signal 4039 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4040 // failed to switch, state wasn't running? 4041 ShouldNotReachHere(); 4042 return false; 4043 } 4044 4045 if (sr_notify(osthread) != 0) { 4046 ShouldNotReachHere(); 4047 } 4048 4049 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4050 while (true) { 4051 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4052 break; 4053 } else { 4054 // timeout 4055 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4056 if (cancelled == os::SuspendResume::SR_RUNNING) { 4057 return false; 4058 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4059 // make sure that we consume the signal on the semaphore as well 4060 sr_semaphore.wait(); 4061 break; 4062 } else { 4063 ShouldNotReachHere(); 4064 return false; 4065 } 4066 } 4067 } 4068 4069 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4070 return true; 4071 } 4072 4073 static void do_resume(OSThread* osthread) { 4074 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4075 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4076 4077 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4078 // failed to switch to WAKEUP_REQUEST 4079 ShouldNotReachHere(); 4080 return; 4081 } 4082 4083 while (true) { 4084 if (sr_notify(osthread) == 0) { 4085 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4086 if (osthread->sr.is_running()) { 4087 return; 4088 } 4089 } 4090 } else { 4091 ShouldNotReachHere(); 4092 } 4093 } 4094 4095 guarantee(osthread->sr.is_running(), "Must be running!"); 4096 } 4097 4098 /////////////////////////////////////////////////////////////////////////////////// 4099 // signal handling (except suspend/resume) 4100 4101 // This routine may be used by user applications as a "hook" to catch signals. 4102 // The user-defined signal handler must pass unrecognized signals to this 4103 // routine, and if it returns true (non-zero), then the signal handler must 4104 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4105 // routine will never retun false (zero), but instead will execute a VM panic 4106 // routine kill the process. 4107 // 4108 // If this routine returns false, it is OK to call it again. This allows 4109 // the user-defined signal handler to perform checks either before or after 4110 // the VM performs its own checks. Naturally, the user code would be making 4111 // a serious error if it tried to handle an exception (such as a null check 4112 // or breakpoint) that the VM was generating for its own correct operation. 4113 // 4114 // This routine may recognize any of the following kinds of signals: 4115 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4116 // It should be consulted by handlers for any of those signals. 4117 // 4118 // The caller of this routine must pass in the three arguments supplied 4119 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4120 // field of the structure passed to sigaction(). This routine assumes that 4121 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4122 // 4123 // Note that the VM will print warnings if it detects conflicting signal 4124 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4125 // 4126 extern "C" JNIEXPORT int 4127 JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 4128 void* ucontext, int abort_if_unrecognized); 4129 4130 void signalHandler(int sig, siginfo_t* info, void* uc) { 4131 assert(info != NULL && uc != NULL, "it must be old kernel"); 4132 int orig_errno = errno; // Preserve errno value over signal handler. 4133 JVM_handle_linux_signal(sig, info, uc, true); 4134 errno = orig_errno; 4135 } 4136 4137 4138 // This boolean allows users to forward their own non-matching signals 4139 // to JVM_handle_linux_signal, harmlessly. 4140 bool os::Linux::signal_handlers_are_installed = false; 4141 4142 // For signal-chaining 4143 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4144 unsigned int os::Linux::sigs = 0; 4145 bool os::Linux::libjsig_is_loaded = false; 4146 typedef struct sigaction *(*get_signal_t)(int); 4147 get_signal_t os::Linux::get_signal_action = NULL; 4148 4149 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4150 struct sigaction *actp = NULL; 4151 4152 if (libjsig_is_loaded) { 4153 // Retrieve the old signal handler from libjsig 4154 actp = (*get_signal_action)(sig); 4155 } 4156 if (actp == NULL) { 4157 // Retrieve the preinstalled signal handler from jvm 4158 actp = get_preinstalled_handler(sig); 4159 } 4160 4161 return actp; 4162 } 4163 4164 static bool call_chained_handler(struct sigaction *actp, int sig, 4165 siginfo_t *siginfo, void *context) { 4166 // Call the old signal handler 4167 if (actp->sa_handler == SIG_DFL) { 4168 // It's more reasonable to let jvm treat it as an unexpected exception 4169 // instead of taking the default action. 4170 return false; 4171 } else if (actp->sa_handler != SIG_IGN) { 4172 if ((actp->sa_flags & SA_NODEFER) == 0) { 4173 // automaticlly block the signal 4174 sigaddset(&(actp->sa_mask), sig); 4175 } 4176 4177 sa_handler_t hand; 4178 sa_sigaction_t sa; 4179 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4180 // retrieve the chained handler 4181 if (siginfo_flag_set) { 4182 sa = actp->sa_sigaction; 4183 } else { 4184 hand = actp->sa_handler; 4185 } 4186 4187 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4188 actp->sa_handler = SIG_DFL; 4189 } 4190 4191 // try to honor the signal mask 4192 sigset_t oset; 4193 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4194 4195 // call into the chained handler 4196 if (siginfo_flag_set) { 4197 (*sa)(sig, siginfo, context); 4198 } else { 4199 (*hand)(sig); 4200 } 4201 4202 // restore the signal mask 4203 pthread_sigmask(SIG_SETMASK, &oset, 0); 4204 } 4205 // Tell jvm's signal handler the signal is taken care of. 4206 return true; 4207 } 4208 4209 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4210 bool chained = false; 4211 // signal-chaining 4212 if (UseSignalChaining) { 4213 struct sigaction *actp = get_chained_signal_action(sig); 4214 if (actp != NULL) { 4215 chained = call_chained_handler(actp, sig, siginfo, context); 4216 } 4217 } 4218 return chained; 4219 } 4220 4221 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4222 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 4223 return &sigact[sig]; 4224 } 4225 return NULL; 4226 } 4227 4228 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4229 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4230 sigact[sig] = oldAct; 4231 sigs |= (unsigned int)1 << sig; 4232 } 4233 4234 // for diagnostic 4235 int os::Linux::sigflags[MAXSIGNUM]; 4236 4237 int os::Linux::get_our_sigflags(int sig) { 4238 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4239 return sigflags[sig]; 4240 } 4241 4242 void os::Linux::set_our_sigflags(int sig, int flags) { 4243 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4244 sigflags[sig] = flags; 4245 } 4246 4247 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4248 // Check for overwrite. 4249 struct sigaction oldAct; 4250 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4251 4252 void* oldhand = oldAct.sa_sigaction 4253 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4254 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4255 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4256 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4257 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4258 if (AllowUserSignalHandlers || !set_installed) { 4259 // Do not overwrite; user takes responsibility to forward to us. 4260 return; 4261 } else if (UseSignalChaining) { 4262 // save the old handler in jvm 4263 save_preinstalled_handler(sig, oldAct); 4264 // libjsig also interposes the sigaction() call below and saves the 4265 // old sigaction on it own. 4266 } else { 4267 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4268 "%#lx for signal %d.", (long)oldhand, sig)); 4269 } 4270 } 4271 4272 struct sigaction sigAct; 4273 sigfillset(&(sigAct.sa_mask)); 4274 sigAct.sa_handler = SIG_DFL; 4275 if (!set_installed) { 4276 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4277 } else { 4278 sigAct.sa_sigaction = signalHandler; 4279 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4280 } 4281 // Save flags, which are set by ours 4282 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4283 sigflags[sig] = sigAct.sa_flags; 4284 4285 int ret = sigaction(sig, &sigAct, &oldAct); 4286 assert(ret == 0, "check"); 4287 4288 void* oldhand2 = oldAct.sa_sigaction 4289 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4290 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4291 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4292 } 4293 4294 // install signal handlers for signals that HotSpot needs to 4295 // handle in order to support Java-level exception handling. 4296 4297 void os::Linux::install_signal_handlers() { 4298 if (!signal_handlers_are_installed) { 4299 signal_handlers_are_installed = true; 4300 4301 // signal-chaining 4302 typedef void (*signal_setting_t)(); 4303 signal_setting_t begin_signal_setting = NULL; 4304 signal_setting_t end_signal_setting = NULL; 4305 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4306 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4307 if (begin_signal_setting != NULL) { 4308 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4309 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4310 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4311 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4312 libjsig_is_loaded = true; 4313 assert(UseSignalChaining, "should enable signal-chaining"); 4314 } 4315 if (libjsig_is_loaded) { 4316 // Tell libjsig jvm is setting signal handlers 4317 (*begin_signal_setting)(); 4318 } 4319 4320 set_signal_handler(SIGSEGV, true); 4321 set_signal_handler(SIGPIPE, true); 4322 set_signal_handler(SIGBUS, true); 4323 set_signal_handler(SIGILL, true); 4324 set_signal_handler(SIGFPE, true); 4325 #if defined(PPC64) 4326 set_signal_handler(SIGTRAP, true); 4327 #endif 4328 set_signal_handler(SIGXFSZ, true); 4329 4330 if (libjsig_is_loaded) { 4331 // Tell libjsig jvm finishes setting signal handlers 4332 (*end_signal_setting)(); 4333 } 4334 4335 // We don't activate signal checker if libjsig is in place, we trust ourselves 4336 // and if UserSignalHandler is installed all bets are off. 4337 // Log that signal checking is off only if -verbose:jni is specified. 4338 if (CheckJNICalls) { 4339 if (libjsig_is_loaded) { 4340 if (PrintJNIResolving) { 4341 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4342 } 4343 check_signals = false; 4344 } 4345 if (AllowUserSignalHandlers) { 4346 if (PrintJNIResolving) { 4347 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4348 } 4349 check_signals = false; 4350 } 4351 } 4352 } 4353 } 4354 4355 // This is the fastest way to get thread cpu time on Linux. 4356 // Returns cpu time (user+sys) for any thread, not only for current. 4357 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4358 // It might work on 2.6.10+ with a special kernel/glibc patch. 4359 // For reference, please, see IEEE Std 1003.1-2004: 4360 // http://www.unix.org/single_unix_specification 4361 4362 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4363 struct timespec tp; 4364 int rc = os::Linux::clock_gettime(clockid, &tp); 4365 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4366 4367 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4368 } 4369 4370 ///// 4371 // glibc on Linux platform uses non-documented flag 4372 // to indicate, that some special sort of signal 4373 // trampoline is used. 4374 // We will never set this flag, and we should 4375 // ignore this flag in our diagnostic 4376 #ifdef SIGNIFICANT_SIGNAL_MASK 4377 #undef SIGNIFICANT_SIGNAL_MASK 4378 #endif 4379 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4380 4381 static const char* get_signal_handler_name(address handler, 4382 char* buf, int buflen) { 4383 int offset; 4384 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4385 if (found) { 4386 // skip directory names 4387 const char *p1, *p2; 4388 p1 = buf; 4389 size_t len = strlen(os::file_separator()); 4390 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4391 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4392 } else { 4393 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4394 } 4395 return buf; 4396 } 4397 4398 static void print_signal_handler(outputStream* st, int sig, 4399 char* buf, size_t buflen) { 4400 struct sigaction sa; 4401 4402 sigaction(sig, NULL, &sa); 4403 4404 // See comment for SIGNIFICANT_SIGNAL_MASK define 4405 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4406 4407 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4408 4409 address handler = (sa.sa_flags & SA_SIGINFO) 4410 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4411 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4412 4413 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4414 st->print("SIG_DFL"); 4415 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4416 st->print("SIG_IGN"); 4417 } else { 4418 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4419 } 4420 4421 st->print(", sa_mask[0]="); 4422 os::Posix::print_signal_set_short(st, &sa.sa_mask); 4423 4424 address rh = VMError::get_resetted_sighandler(sig); 4425 // May be, handler was resetted by VMError? 4426 if(rh != NULL) { 4427 handler = rh; 4428 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4429 } 4430 4431 st->print(", sa_flags="); 4432 os::Posix::print_sa_flags(st, sa.sa_flags); 4433 4434 // Check: is it our handler? 4435 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4436 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4437 // It is our signal handler 4438 // check for flags, reset system-used one! 4439 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4440 st->print( 4441 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4442 os::Linux::get_our_sigflags(sig)); 4443 } 4444 } 4445 st->cr(); 4446 } 4447 4448 4449 #define DO_SIGNAL_CHECK(sig) \ 4450 if (!sigismember(&check_signal_done, sig)) \ 4451 os::Linux::check_signal_handler(sig) 4452 4453 // This method is a periodic task to check for misbehaving JNI applications 4454 // under CheckJNI, we can add any periodic checks here 4455 4456 void os::run_periodic_checks() { 4457 4458 if (check_signals == false) return; 4459 4460 // SEGV and BUS if overridden could potentially prevent 4461 // generation of hs*.log in the event of a crash, debugging 4462 // such a case can be very challenging, so we absolutely 4463 // check the following for a good measure: 4464 DO_SIGNAL_CHECK(SIGSEGV); 4465 DO_SIGNAL_CHECK(SIGILL); 4466 DO_SIGNAL_CHECK(SIGFPE); 4467 DO_SIGNAL_CHECK(SIGBUS); 4468 DO_SIGNAL_CHECK(SIGPIPE); 4469 DO_SIGNAL_CHECK(SIGXFSZ); 4470 #if defined(PPC64) 4471 DO_SIGNAL_CHECK(SIGTRAP); 4472 #endif 4473 4474 // ReduceSignalUsage allows the user to override these handlers 4475 // see comments at the very top and jvm_solaris.h 4476 if (!ReduceSignalUsage) { 4477 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4478 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4479 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4480 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4481 } 4482 4483 DO_SIGNAL_CHECK(SR_signum); 4484 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4485 } 4486 4487 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4488 4489 static os_sigaction_t os_sigaction = NULL; 4490 4491 void os::Linux::check_signal_handler(int sig) { 4492 char buf[O_BUFLEN]; 4493 address jvmHandler = NULL; 4494 4495 4496 struct sigaction act; 4497 if (os_sigaction == NULL) { 4498 // only trust the default sigaction, in case it has been interposed 4499 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4500 if (os_sigaction == NULL) return; 4501 } 4502 4503 os_sigaction(sig, (struct sigaction*)NULL, &act); 4504 4505 4506 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4507 4508 address thisHandler = (act.sa_flags & SA_SIGINFO) 4509 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4510 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 4511 4512 4513 switch(sig) { 4514 case SIGSEGV: 4515 case SIGBUS: 4516 case SIGFPE: 4517 case SIGPIPE: 4518 case SIGILL: 4519 case SIGXFSZ: 4520 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4521 break; 4522 4523 case SHUTDOWN1_SIGNAL: 4524 case SHUTDOWN2_SIGNAL: 4525 case SHUTDOWN3_SIGNAL: 4526 case BREAK_SIGNAL: 4527 jvmHandler = (address)user_handler(); 4528 break; 4529 4530 case INTERRUPT_SIGNAL: 4531 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4532 break; 4533 4534 default: 4535 if (sig == SR_signum) { 4536 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4537 } else { 4538 return; 4539 } 4540 break; 4541 } 4542 4543 if (thisHandler != jvmHandler) { 4544 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4545 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4546 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4547 // No need to check this sig any longer 4548 sigaddset(&check_signal_done, sig); 4549 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN 4550 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) { 4551 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell", 4552 exception_name(sig, buf, O_BUFLEN)); 4553 } 4554 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4555 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4556 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4557 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4558 // No need to check this sig any longer 4559 sigaddset(&check_signal_done, sig); 4560 } 4561 4562 // Dump all the signal 4563 if (sigismember(&check_signal_done, sig)) { 4564 print_signal_handlers(tty, buf, O_BUFLEN); 4565 } 4566 } 4567 4568 extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 4569 4570 extern bool signal_name(int signo, char* buf, size_t len); 4571 4572 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4573 if (0 < exception_code && exception_code <= SIGRTMAX) { 4574 // signal 4575 if (!signal_name(exception_code, buf, size)) { 4576 jio_snprintf(buf, size, "SIG%d", exception_code); 4577 } 4578 return buf; 4579 } else { 4580 return NULL; 4581 } 4582 } 4583 4584 // this is called _before_ the most of global arguments have been parsed 4585 void os::init(void) { 4586 char dummy; /* used to get a guess on initial stack address */ 4587 // first_hrtime = gethrtime(); 4588 4589 // With LinuxThreads the JavaMain thread pid (primordial thread) 4590 // is different than the pid of the java launcher thread. 4591 // So, on Linux, the launcher thread pid is passed to the VM 4592 // via the sun.java.launcher.pid property. 4593 // Use this property instead of getpid() if it was correctly passed. 4594 // See bug 6351349. 4595 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4596 4597 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4598 4599 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4600 4601 init_random(1234567); 4602 4603 ThreadCritical::initialize(); 4604 4605 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4606 if (Linux::page_size() == -1) { 4607 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4608 strerror(errno))); 4609 } 4610 init_page_sizes((size_t) Linux::page_size()); 4611 4612 Linux::initialize_system_info(); 4613 4614 // main_thread points to the aboriginal thread 4615 Linux::_main_thread = pthread_self(); 4616 4617 Linux::clock_init(); 4618 initial_time_count = javaTimeNanos(); 4619 4620 // pthread_condattr initialization for monotonic clock 4621 int status; 4622 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4623 if ((status = pthread_condattr_init(_condattr)) != 0) { 4624 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4625 } 4626 // Only set the clock if CLOCK_MONOTONIC is available 4627 if (os::supports_monotonic_clock()) { 4628 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4629 if (status == EINVAL) { 4630 warning("Unable to use monotonic clock with relative timed-waits" \ 4631 " - changes to the time-of-day clock may have adverse affects"); 4632 } else { 4633 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4634 } 4635 } 4636 } 4637 // else it defaults to CLOCK_REALTIME 4638 4639 pthread_mutex_init(&dl_mutex, NULL); 4640 4641 // If the pagesize of the VM is greater than 8K determine the appropriate 4642 // number of initial guard pages. The user can change this with the 4643 // command line arguments, if needed. 4644 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4645 StackYellowPages = 1; 4646 StackRedPages = 1; 4647 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4648 } 4649 } 4650 4651 // To install functions for atexit system call 4652 extern "C" { 4653 static void perfMemory_exit_helper() { 4654 perfMemory_exit(); 4655 } 4656 } 4657 4658 // this is called _after_ the global arguments have been parsed 4659 jint os::init_2(void) 4660 { 4661 Linux::fast_thread_clock_init(); 4662 4663 // Allocate a single page and mark it as readable for safepoint polling 4664 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4665 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 4666 4667 os::set_polling_page( polling_page ); 4668 4669 #ifndef PRODUCT 4670 if(Verbose && PrintMiscellaneous) 4671 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 4672 #endif 4673 4674 if (!UseMembar) { 4675 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4676 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4677 os::set_memory_serialize_page( mem_serialize_page ); 4678 4679 #ifndef PRODUCT 4680 if(Verbose && PrintMiscellaneous) 4681 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 4682 #endif 4683 } 4684 4685 // initialize suspend/resume support - must do this before signal_sets_init() 4686 if (SR_initialize() != 0) { 4687 perror("SR_initialize failed"); 4688 return JNI_ERR; 4689 } 4690 4691 Linux::signal_sets_init(); 4692 Linux::install_signal_handlers(); 4693 4694 // Check minimum allowable stack size for thread creation and to initialize 4695 // the java system classes, including StackOverflowError - depends on page 4696 // size. Add a page for compiler2 recursion in main thread. 4697 // Add in 2*BytesPerWord times page size to account for VM stack during 4698 // class initialization depending on 32 or 64 bit VM. 4699 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4700 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4701 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4702 4703 size_t threadStackSizeInBytes = ThreadStackSize * K; 4704 if (threadStackSizeInBytes != 0 && 4705 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4706 tty->print_cr("\nThe stack size specified is too small, " 4707 "Specify at least %dk", 4708 os::Linux::min_stack_allowed/ K); 4709 return JNI_ERR; 4710 } 4711 4712 // Make the stack size a multiple of the page size so that 4713 // the yellow/red zones can be guarded. 4714 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4715 vm_page_size())); 4716 4717 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4718 4719 #if defined(IA32) 4720 workaround_expand_exec_shield_cs_limit(); 4721 #endif 4722 4723 Linux::libpthread_init(); 4724 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4725 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4726 Linux::glibc_version(), Linux::libpthread_version(), 4727 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4728 } 4729 4730 if (UseNUMA) { 4731 if (!Linux::libnuma_init()) { 4732 UseNUMA = false; 4733 } else { 4734 if ((Linux::numa_max_node() < 1)) { 4735 // There's only one node(they start from 0), disable NUMA. 4736 UseNUMA = false; 4737 } 4738 } 4739 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4740 // we can make the adaptive lgrp chunk resizing work. If the user specified 4741 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4742 // disable adaptive resizing. 4743 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4744 if (FLAG_IS_DEFAULT(UseNUMA)) { 4745 UseNUMA = false; 4746 } else { 4747 if (FLAG_IS_DEFAULT(UseLargePages) && 4748 FLAG_IS_DEFAULT(UseSHM) && 4749 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4750 UseLargePages = false; 4751 } else { 4752 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4753 UseAdaptiveSizePolicy = false; 4754 UseAdaptiveNUMAChunkSizing = false; 4755 } 4756 } 4757 } 4758 if (!UseNUMA && ForceNUMA) { 4759 UseNUMA = true; 4760 } 4761 } 4762 4763 if (MaxFDLimit) { 4764 // set the number of file descriptors to max. print out error 4765 // if getrlimit/setrlimit fails but continue regardless. 4766 struct rlimit nbr_files; 4767 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4768 if (status != 0) { 4769 if (PrintMiscellaneous && (Verbose || WizardMode)) 4770 perror("os::init_2 getrlimit failed"); 4771 } else { 4772 nbr_files.rlim_cur = nbr_files.rlim_max; 4773 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4774 if (status != 0) { 4775 if (PrintMiscellaneous && (Verbose || WizardMode)) 4776 perror("os::init_2 setrlimit failed"); 4777 } 4778 } 4779 } 4780 4781 // Initialize lock used to serialize thread creation (see os::create_thread) 4782 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4783 4784 // at-exit methods are called in the reverse order of their registration. 4785 // atexit functions are called on return from main or as a result of a 4786 // call to exit(3C). There can be only 32 of these functions registered 4787 // and atexit() does not set errno. 4788 4789 if (PerfAllowAtExitRegistration) { 4790 // only register atexit functions if PerfAllowAtExitRegistration is set. 4791 // atexit functions can be delayed until process exit time, which 4792 // can be problematic for embedded VM situations. Embedded VMs should 4793 // call DestroyJavaVM() to assure that VM resources are released. 4794 4795 // note: perfMemory_exit_helper atexit function may be removed in 4796 // the future if the appropriate cleanup code can be added to the 4797 // VM_Exit VMOperation's doit method. 4798 if (atexit(perfMemory_exit_helper) != 0) { 4799 warning("os::init_2 atexit(perfMemory_exit_helper) failed"); 4800 } 4801 } 4802 4803 // initialize thread priority policy 4804 prio_init(); 4805 4806 return JNI_OK; 4807 } 4808 4809 // this is called at the end of vm_initialization 4810 void os::init_3(void) { 4811 #ifdef JAVASE_EMBEDDED 4812 // Start the MemNotifyThread 4813 if (LowMemoryProtection) { 4814 MemNotifyThread::start(); 4815 } 4816 return; 4817 #endif 4818 } 4819 4820 // Mark the polling page as unreadable 4821 void os::make_polling_page_unreadable(void) { 4822 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 4823 fatal("Could not disable polling page"); 4824 }; 4825 4826 // Mark the polling page as readable 4827 void os::make_polling_page_readable(void) { 4828 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4829 fatal("Could not enable polling page"); 4830 } 4831 }; 4832 4833 int os::active_processor_count() { 4834 // Linux doesn't yet have a (official) notion of processor sets, 4835 // so just return the number of online processors. 4836 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4837 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4838 return online_cpus; 4839 } 4840 4841 void os::set_native_thread_name(const char *name) { 4842 // Not yet implemented. 4843 return; 4844 } 4845 4846 bool os::distribute_processes(uint length, uint* distribution) { 4847 // Not yet implemented. 4848 return false; 4849 } 4850 4851 bool os::bind_to_processor(uint processor_id) { 4852 // Not yet implemented. 4853 return false; 4854 } 4855 4856 /// 4857 4858 void os::SuspendedThreadTask::internal_do_task() { 4859 if (do_suspend(_thread->osthread())) { 4860 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4861 do_task(context); 4862 do_resume(_thread->osthread()); 4863 } 4864 } 4865 4866 class PcFetcher : public os::SuspendedThreadTask { 4867 public: 4868 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4869 ExtendedPC result(); 4870 protected: 4871 void do_task(const os::SuspendedThreadTaskContext& context); 4872 private: 4873 ExtendedPC _epc; 4874 }; 4875 4876 ExtendedPC PcFetcher::result() { 4877 guarantee(is_done(), "task is not done yet."); 4878 return _epc; 4879 } 4880 4881 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 4882 Thread* thread = context.thread(); 4883 OSThread* osthread = thread->osthread(); 4884 if (osthread->ucontext() != NULL) { 4885 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 4886 } else { 4887 // NULL context is unexpected, double-check this is the VMThread 4888 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4889 } 4890 } 4891 4892 // Suspends the target using the signal mechanism and then grabs the PC before 4893 // resuming the target. Used by the flat-profiler only 4894 ExtendedPC os::get_thread_pc(Thread* thread) { 4895 // Make sure that it is called by the watcher for the VMThread 4896 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4897 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4898 4899 PcFetcher fetcher(thread); 4900 fetcher.run(); 4901 return fetcher.result(); 4902 } 4903 4904 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 4905 { 4906 if (is_NPTL()) { 4907 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4908 } else { 4909 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4910 // word back to default 64bit precision if condvar is signaled. Java 4911 // wants 53bit precision. Save and restore current value. 4912 int fpu = get_fpu_control_word(); 4913 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4914 set_fpu_control_word(fpu); 4915 return status; 4916 } 4917 } 4918 4919 //////////////////////////////////////////////////////////////////////////////// 4920 // debug support 4921 4922 bool os::find(address addr, outputStream* st) { 4923 Dl_info dlinfo; 4924 memset(&dlinfo, 0, sizeof(dlinfo)); 4925 if (dladdr(addr, &dlinfo) != 0) { 4926 st->print(PTR_FORMAT ": ", addr); 4927 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 4928 st->print("%s+%#x", dlinfo.dli_sname, 4929 addr - (intptr_t)dlinfo.dli_saddr); 4930 } else if (dlinfo.dli_fbase != NULL) { 4931 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4932 } else { 4933 st->print("<absolute address>"); 4934 } 4935 if (dlinfo.dli_fname != NULL) { 4936 st->print(" in %s", dlinfo.dli_fname); 4937 } 4938 if (dlinfo.dli_fbase != NULL) { 4939 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4940 } 4941 st->cr(); 4942 4943 if (Verbose) { 4944 // decode some bytes around the PC 4945 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 4946 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 4947 address lowest = (address) dlinfo.dli_sname; 4948 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4949 if (begin < lowest) begin = lowest; 4950 Dl_info dlinfo2; 4951 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 4952 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 4953 end = (address) dlinfo2.dli_saddr; 4954 Disassembler::decode(begin, end, st); 4955 } 4956 return true; 4957 } 4958 return false; 4959 } 4960 4961 //////////////////////////////////////////////////////////////////////////////// 4962 // misc 4963 4964 // This does not do anything on Linux. This is basically a hook for being 4965 // able to use structured exception handling (thread-local exception filters) 4966 // on, e.g., Win32. 4967 void 4968 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 4969 JavaCallArguments* args, Thread* thread) { 4970 f(value, method, args, thread); 4971 } 4972 4973 void os::print_statistics() { 4974 } 4975 4976 int os::message_box(const char* title, const char* message) { 4977 int i; 4978 fdStream err(defaultStream::error_fd()); 4979 for (i = 0; i < 78; i++) err.print_raw("="); 4980 err.cr(); 4981 err.print_raw_cr(title); 4982 for (i = 0; i < 78; i++) err.print_raw("-"); 4983 err.cr(); 4984 err.print_raw_cr(message); 4985 for (i = 0; i < 78; i++) err.print_raw("="); 4986 err.cr(); 4987 4988 char buf[16]; 4989 // Prevent process from exiting upon "read error" without consuming all CPU 4990 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 4991 4992 return buf[0] == 'y' || buf[0] == 'Y'; 4993 } 4994 4995 int os::stat(const char *path, struct stat *sbuf) { 4996 char pathbuf[MAX_PATH]; 4997 if (strlen(path) > MAX_PATH - 1) { 4998 errno = ENAMETOOLONG; 4999 return -1; 5000 } 5001 os::native_path(strcpy(pathbuf, path)); 5002 return ::stat(pathbuf, sbuf); 5003 } 5004 5005 bool os::check_heap(bool force) { 5006 return true; 5007 } 5008 5009 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 5010 return ::vsnprintf(buf, count, format, args); 5011 } 5012 5013 // Is a (classpath) directory empty? 5014 bool os::dir_is_empty(const char* path) { 5015 DIR *dir = NULL; 5016 struct dirent *ptr; 5017 5018 dir = opendir(path); 5019 if (dir == NULL) return true; 5020 5021 /* Scan the directory */ 5022 bool result = true; 5023 char buf[sizeof(struct dirent) + MAX_PATH]; 5024 while (result && (ptr = ::readdir(dir)) != NULL) { 5025 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5026 result = false; 5027 } 5028 } 5029 closedir(dir); 5030 return result; 5031 } 5032 5033 // This code originates from JDK's sysOpen and open64_w 5034 // from src/solaris/hpi/src/system_md.c 5035 5036 #ifndef O_DELETE 5037 #define O_DELETE 0x10000 5038 #endif 5039 5040 // Open a file. Unlink the file immediately after open returns 5041 // if the specified oflag has the O_DELETE flag set. 5042 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c 5043 5044 int os::open(const char *path, int oflag, int mode) { 5045 5046 if (strlen(path) > MAX_PATH - 1) { 5047 errno = ENAMETOOLONG; 5048 return -1; 5049 } 5050 int fd; 5051 int o_delete = (oflag & O_DELETE); 5052 oflag = oflag & ~O_DELETE; 5053 5054 fd = ::open64(path, oflag, mode); 5055 if (fd == -1) return -1; 5056 5057 //If the open succeeded, the file might still be a directory 5058 { 5059 struct stat64 buf64; 5060 int ret = ::fstat64(fd, &buf64); 5061 int st_mode = buf64.st_mode; 5062 5063 if (ret != -1) { 5064 if ((st_mode & S_IFMT) == S_IFDIR) { 5065 errno = EISDIR; 5066 ::close(fd); 5067 return -1; 5068 } 5069 } else { 5070 ::close(fd); 5071 return -1; 5072 } 5073 } 5074 5075 /* 5076 * All file descriptors that are opened in the JVM and not 5077 * specifically destined for a subprocess should have the 5078 * close-on-exec flag set. If we don't set it, then careless 3rd 5079 * party native code might fork and exec without closing all 5080 * appropriate file descriptors (e.g. as we do in closeDescriptors in 5081 * UNIXProcess.c), and this in turn might: 5082 * 5083 * - cause end-of-file to fail to be detected on some file 5084 * descriptors, resulting in mysterious hangs, or 5085 * 5086 * - might cause an fopen in the subprocess to fail on a system 5087 * suffering from bug 1085341. 5088 * 5089 * (Yes, the default setting of the close-on-exec flag is a Unix 5090 * design flaw) 5091 * 5092 * See: 5093 * 1085341: 32-bit stdio routines should support file descriptors >255 5094 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5095 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5096 */ 5097 #ifdef FD_CLOEXEC 5098 { 5099 int flags = ::fcntl(fd, F_GETFD); 5100 if (flags != -1) 5101 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5102 } 5103 #endif 5104 5105 if (o_delete != 0) { 5106 ::unlink(path); 5107 } 5108 return fd; 5109 } 5110 5111 5112 // create binary file, rewriting existing file if required 5113 int os::create_binary_file(const char* path, bool rewrite_existing) { 5114 int oflags = O_WRONLY | O_CREAT; 5115 if (!rewrite_existing) { 5116 oflags |= O_EXCL; 5117 } 5118 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5119 } 5120 5121 // return current position of file pointer 5122 jlong os::current_file_offset(int fd) { 5123 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5124 } 5125 5126 // move file pointer to the specified offset 5127 jlong os::seek_to_file_offset(int fd, jlong offset) { 5128 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5129 } 5130 5131 // This code originates from JDK's sysAvailable 5132 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5133 5134 int os::available(int fd, jlong *bytes) { 5135 jlong cur, end; 5136 int mode; 5137 struct stat64 buf64; 5138 5139 if (::fstat64(fd, &buf64) >= 0) { 5140 mode = buf64.st_mode; 5141 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5142 /* 5143 * XXX: is the following call interruptible? If so, this might 5144 * need to go through the INTERRUPT_IO() wrapper as for other 5145 * blocking, interruptible calls in this file. 5146 */ 5147 int n; 5148 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5149 *bytes = n; 5150 return 1; 5151 } 5152 } 5153 } 5154 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5155 return 0; 5156 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5157 return 0; 5158 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5159 return 0; 5160 } 5161 *bytes = end - cur; 5162 return 1; 5163 } 5164 5165 int os::socket_available(int fd, jint *pbytes) { 5166 // Linux doc says EINTR not returned, unlike Solaris 5167 int ret = ::ioctl(fd, FIONREAD, pbytes); 5168 5169 //%% note ioctl can return 0 when successful, JVM_SocketAvailable 5170 // is expected to return 0 on failure and 1 on success to the jdk. 5171 return (ret < 0) ? 0 : 1; 5172 } 5173 5174 // Map a block of memory. 5175 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5176 char *addr, size_t bytes, bool read_only, 5177 bool allow_exec) { 5178 int prot; 5179 int flags = MAP_PRIVATE; 5180 5181 if (read_only) { 5182 prot = PROT_READ; 5183 } else { 5184 prot = PROT_READ | PROT_WRITE; 5185 } 5186 5187 if (allow_exec) { 5188 prot |= PROT_EXEC; 5189 } 5190 5191 if (addr != NULL) { 5192 flags |= MAP_FIXED; 5193 } 5194 5195 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5196 fd, file_offset); 5197 if (mapped_address == MAP_FAILED) { 5198 return NULL; 5199 } 5200 return mapped_address; 5201 } 5202 5203 5204 // Remap a block of memory. 5205 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5206 char *addr, size_t bytes, bool read_only, 5207 bool allow_exec) { 5208 // same as map_memory() on this OS 5209 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5210 allow_exec); 5211 } 5212 5213 5214 // Unmap a block of memory. 5215 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5216 return munmap(addr, bytes) == 0; 5217 } 5218 5219 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5220 5221 static clockid_t thread_cpu_clockid(Thread* thread) { 5222 pthread_t tid = thread->osthread()->pthread_id(); 5223 clockid_t clockid; 5224 5225 // Get thread clockid 5226 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5227 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5228 return clockid; 5229 } 5230 5231 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5232 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5233 // of a thread. 5234 // 5235 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5236 // the fast estimate available on the platform. 5237 5238 jlong os::current_thread_cpu_time() { 5239 if (os::Linux::supports_fast_thread_cpu_time()) { 5240 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5241 } else { 5242 // return user + sys since the cost is the same 5243 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5244 } 5245 } 5246 5247 jlong os::thread_cpu_time(Thread* thread) { 5248 // consistent with what current_thread_cpu_time() returns 5249 if (os::Linux::supports_fast_thread_cpu_time()) { 5250 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5251 } else { 5252 return slow_thread_cpu_time(thread, true /* user + sys */); 5253 } 5254 } 5255 5256 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5257 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5258 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5259 } else { 5260 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5261 } 5262 } 5263 5264 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5265 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5266 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5267 } else { 5268 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5269 } 5270 } 5271 5272 // 5273 // -1 on error. 5274 // 5275 5276 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5277 pid_t tid = thread->osthread()->thread_id(); 5278 char *s; 5279 char stat[2048]; 5280 int statlen; 5281 char proc_name[64]; 5282 int count; 5283 long sys_time, user_time; 5284 char cdummy; 5285 int idummy; 5286 long ldummy; 5287 FILE *fp; 5288 5289 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid); 5290 fp = fopen(proc_name, "r"); 5291 if ( fp == NULL ) return -1; 5292 statlen = fread(stat, 1, 2047, fp); 5293 stat[statlen] = '\0'; 5294 fclose(fp); 5295 5296 // Skip pid and the command string. Note that we could be dealing with 5297 // weird command names, e.g. user could decide to rename java launcher 5298 // to "java 1.4.2 :)", then the stat file would look like 5299 // 1234 (java 1.4.2 :)) R ... ... 5300 // We don't really need to know the command string, just find the last 5301 // occurrence of ")" and then start parsing from there. See bug 4726580. 5302 s = strrchr(stat, ')'); 5303 if (s == NULL ) return -1; 5304 5305 // Skip blank chars 5306 do s++; while (isspace(*s)); 5307 5308 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5309 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5310 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5311 &user_time, &sys_time); 5312 if ( count != 13 ) return -1; 5313 if (user_sys_cpu_time) { 5314 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5315 } else { 5316 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5317 } 5318 } 5319 5320 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5321 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5322 info_ptr->may_skip_backward = false; // elapsed time not wall time 5323 info_ptr->may_skip_forward = false; // elapsed time not wall time 5324 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5325 } 5326 5327 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5328 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5329 info_ptr->may_skip_backward = false; // elapsed time not wall time 5330 info_ptr->may_skip_forward = false; // elapsed time not wall time 5331 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5332 } 5333 5334 bool os::is_thread_cpu_time_supported() { 5335 return true; 5336 } 5337 5338 // System loadavg support. Returns -1 if load average cannot be obtained. 5339 // Linux doesn't yet have a (official) notion of processor sets, 5340 // so just return the system wide load average. 5341 int os::loadavg(double loadavg[], int nelem) { 5342 return ::getloadavg(loadavg, nelem); 5343 } 5344 5345 void os::pause() { 5346 char filename[MAX_PATH]; 5347 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5348 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5349 } else { 5350 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5351 } 5352 5353 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5354 if (fd != -1) { 5355 struct stat buf; 5356 ::close(fd); 5357 while (::stat(filename, &buf) == 0) { 5358 (void)::poll(NULL, 0, 100); 5359 } 5360 } else { 5361 jio_fprintf(stderr, 5362 "Could not open pause file '%s', continuing immediately.\n", filename); 5363 } 5364 } 5365 5366 5367 // Refer to the comments in os_solaris.cpp park-unpark. 5368 // 5369 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5370 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5371 // For specifics regarding the bug see GLIBC BUGID 261237 : 5372 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5373 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5374 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5375 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5376 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5377 // and monitorenter when we're using 1-0 locking. All those operations may result in 5378 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5379 // of libpthread avoids the problem, but isn't practical. 5380 // 5381 // Possible remedies: 5382 // 5383 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5384 // This is palliative and probabilistic, however. If the thread is preempted 5385 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5386 // than the minimum period may have passed, and the abstime may be stale (in the 5387 // past) resultin in a hang. Using this technique reduces the odds of a hang 5388 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5389 // 5390 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5391 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5392 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5393 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5394 // thread. 5395 // 5396 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5397 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5398 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5399 // This also works well. In fact it avoids kernel-level scalability impediments 5400 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5401 // timers in a graceful fashion. 5402 // 5403 // 4. When the abstime value is in the past it appears that control returns 5404 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5405 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5406 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5407 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5408 // It may be possible to avoid reinitialization by checking the return 5409 // value from pthread_cond_timedwait(). In addition to reinitializing the 5410 // condvar we must establish the invariant that cond_signal() is only called 5411 // within critical sections protected by the adjunct mutex. This prevents 5412 // cond_signal() from "seeing" a condvar that's in the midst of being 5413 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5414 // desirable signal-after-unlock optimization that avoids futile context switching. 5415 // 5416 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5417 // structure when a condvar is used or initialized. cond_destroy() would 5418 // release the helper structure. Our reinitialize-after-timedwait fix 5419 // put excessive stress on malloc/free and locks protecting the c-heap. 5420 // 5421 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5422 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5423 // and only enabling the work-around for vulnerable environments. 5424 5425 // utility to compute the abstime argument to timedwait: 5426 // millis is the relative timeout time 5427 // abstime will be the absolute timeout time 5428 // TODO: replace compute_abstime() with unpackTime() 5429 5430 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5431 if (millis < 0) millis = 0; 5432 5433 jlong seconds = millis / 1000; 5434 millis %= 1000; 5435 if (seconds > 50000000) { // see man cond_timedwait(3T) 5436 seconds = 50000000; 5437 } 5438 5439 if (os::supports_monotonic_clock()) { 5440 struct timespec now; 5441 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5442 assert_status(status == 0, status, "clock_gettime"); 5443 abstime->tv_sec = now.tv_sec + seconds; 5444 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5445 if (nanos >= NANOSECS_PER_SEC) { 5446 abstime->tv_sec += 1; 5447 nanos -= NANOSECS_PER_SEC; 5448 } 5449 abstime->tv_nsec = nanos; 5450 } else { 5451 struct timeval now; 5452 int status = gettimeofday(&now, NULL); 5453 assert(status == 0, "gettimeofday"); 5454 abstime->tv_sec = now.tv_sec + seconds; 5455 long usec = now.tv_usec + millis * 1000; 5456 if (usec >= 1000000) { 5457 abstime->tv_sec += 1; 5458 usec -= 1000000; 5459 } 5460 abstime->tv_nsec = usec * 1000; 5461 } 5462 return abstime; 5463 } 5464 5465 5466 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 5467 // Conceptually TryPark() should be equivalent to park(0). 5468 5469 int os::PlatformEvent::TryPark() { 5470 for (;;) { 5471 const int v = _Event ; 5472 guarantee ((v == 0) || (v == 1), "invariant") ; 5473 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 5474 } 5475 } 5476 5477 void os::PlatformEvent::park() { // AKA "down()" 5478 // Invariant: Only the thread associated with the Event/PlatformEvent 5479 // may call park(). 5480 // TODO: assert that _Assoc != NULL or _Assoc == Self 5481 int v ; 5482 for (;;) { 5483 v = _Event ; 5484 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5485 } 5486 guarantee (v >= 0, "invariant") ; 5487 if (v == 0) { 5488 // Do this the hard way by blocking ... 5489 int status = pthread_mutex_lock(_mutex); 5490 assert_status(status == 0, status, "mutex_lock"); 5491 guarantee (_nParked == 0, "invariant") ; 5492 ++ _nParked ; 5493 while (_Event < 0) { 5494 status = pthread_cond_wait(_cond, _mutex); 5495 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5496 // Treat this the same as if the wait was interrupted 5497 if (status == ETIME) { status = EINTR; } 5498 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5499 } 5500 -- _nParked ; 5501 5502 _Event = 0 ; 5503 status = pthread_mutex_unlock(_mutex); 5504 assert_status(status == 0, status, "mutex_unlock"); 5505 // Paranoia to ensure our locked and lock-free paths interact 5506 // correctly with each other. 5507 OrderAccess::fence(); 5508 } 5509 guarantee (_Event >= 0, "invariant") ; 5510 } 5511 5512 int os::PlatformEvent::park(jlong millis) { 5513 guarantee (_nParked == 0, "invariant") ; 5514 5515 int v ; 5516 for (;;) { 5517 v = _Event ; 5518 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 5519 } 5520 guarantee (v >= 0, "invariant") ; 5521 if (v != 0) return OS_OK ; 5522 5523 // We do this the hard way, by blocking the thread. 5524 // Consider enforcing a minimum timeout value. 5525 struct timespec abst; 5526 compute_abstime(&abst, millis); 5527 5528 int ret = OS_TIMEOUT; 5529 int status = pthread_mutex_lock(_mutex); 5530 assert_status(status == 0, status, "mutex_lock"); 5531 guarantee (_nParked == 0, "invariant") ; 5532 ++_nParked ; 5533 5534 // Object.wait(timo) will return because of 5535 // (a) notification 5536 // (b) timeout 5537 // (c) thread.interrupt 5538 // 5539 // Thread.interrupt and object.notify{All} both call Event::set. 5540 // That is, we treat thread.interrupt as a special case of notification. 5541 // The underlying Solaris implementation, cond_timedwait, admits 5542 // spurious/premature wakeups, but the JLS/JVM spec prevents the 5543 // JVM from making those visible to Java code. As such, we must 5544 // filter out spurious wakeups. We assume all ETIME returns are valid. 5545 // 5546 // TODO: properly differentiate simultaneous notify+interrupt. 5547 // In that case, we should propagate the notify to another waiter. 5548 5549 while (_Event < 0) { 5550 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5551 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5552 pthread_cond_destroy (_cond); 5553 pthread_cond_init (_cond, os::Linux::condAttr()) ; 5554 } 5555 assert_status(status == 0 || status == EINTR || 5556 status == ETIME || status == ETIMEDOUT, 5557 status, "cond_timedwait"); 5558 if (!FilterSpuriousWakeups) break ; // previous semantics 5559 if (status == ETIME || status == ETIMEDOUT) break ; 5560 // We consume and ignore EINTR and spurious wakeups. 5561 } 5562 --_nParked ; 5563 if (_Event >= 0) { 5564 ret = OS_OK; 5565 } 5566 _Event = 0 ; 5567 status = pthread_mutex_unlock(_mutex); 5568 assert_status(status == 0, status, "mutex_unlock"); 5569 assert (_nParked == 0, "invariant") ; 5570 // Paranoia to ensure our locked and lock-free paths interact 5571 // correctly with each other. 5572 OrderAccess::fence(); 5573 return ret; 5574 } 5575 5576 void os::PlatformEvent::unpark() { 5577 // Transitions for _Event: 5578 // 0 :=> 1 5579 // 1 :=> 1 5580 // -1 :=> either 0 or 1; must signal target thread 5581 // That is, we can safely transition _Event from -1 to either 5582 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back 5583 // unpark() calls. 5584 // See also: "Semaphores in Plan 9" by Mullender & Cox 5585 // 5586 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5587 // that it will take two back-to-back park() calls for the owning 5588 // thread to block. This has the benefit of forcing a spurious return 5589 // from the first park() call after an unpark() call which will help 5590 // shake out uses of park() and unpark() without condition variables. 5591 5592 if (Atomic::xchg(1, &_Event) >= 0) return; 5593 5594 // Wait for the thread associated with the event to vacate 5595 int status = pthread_mutex_lock(_mutex); 5596 assert_status(status == 0, status, "mutex_lock"); 5597 int AnyWaiters = _nParked; 5598 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5599 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5600 AnyWaiters = 0; 5601 pthread_cond_signal(_cond); 5602 } 5603 status = pthread_mutex_unlock(_mutex); 5604 assert_status(status == 0, status, "mutex_unlock"); 5605 if (AnyWaiters != 0) { 5606 status = pthread_cond_signal(_cond); 5607 assert_status(status == 0, status, "cond_signal"); 5608 } 5609 5610 // Note that we signal() _after dropping the lock for "immortal" Events. 5611 // This is safe and avoids a common class of futile wakeups. In rare 5612 // circumstances this can cause a thread to return prematurely from 5613 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 5614 // simply re-test the condition and re-park itself. 5615 } 5616 5617 5618 // JSR166 5619 // ------------------------------------------------------- 5620 5621 /* 5622 * The solaris and linux implementations of park/unpark are fairly 5623 * conservative for now, but can be improved. They currently use a 5624 * mutex/condvar pair, plus a a count. 5625 * Park decrements count if > 0, else does a condvar wait. Unpark 5626 * sets count to 1 and signals condvar. Only one thread ever waits 5627 * on the condvar. Contention seen when trying to park implies that someone 5628 * is unparking you, so don't wait. And spurious returns are fine, so there 5629 * is no need to track notifications. 5630 */ 5631 5632 /* 5633 * This code is common to linux and solaris and will be moved to a 5634 * common place in dolphin. 5635 * 5636 * The passed in time value is either a relative time in nanoseconds 5637 * or an absolute time in milliseconds. Either way it has to be unpacked 5638 * into suitable seconds and nanoseconds components and stored in the 5639 * given timespec structure. 5640 * Given time is a 64-bit value and the time_t used in the timespec is only 5641 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 5642 * overflow if times way in the future are given. Further on Solaris versions 5643 * prior to 10 there is a restriction (see cond_timedwait) that the specified 5644 * number of seconds, in abstime, is less than current_time + 100,000,000. 5645 * As it will be 28 years before "now + 100000000" will overflow we can 5646 * ignore overflow and just impose a hard-limit on seconds using the value 5647 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 5648 * years from "now". 5649 */ 5650 5651 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5652 assert (time > 0, "convertTime"); 5653 time_t max_secs = 0; 5654 5655 if (!os::supports_monotonic_clock() || isAbsolute) { 5656 struct timeval now; 5657 int status = gettimeofday(&now, NULL); 5658 assert(status == 0, "gettimeofday"); 5659 5660 max_secs = now.tv_sec + MAX_SECS; 5661 5662 if (isAbsolute) { 5663 jlong secs = time / 1000; 5664 if (secs > max_secs) { 5665 absTime->tv_sec = max_secs; 5666 } else { 5667 absTime->tv_sec = secs; 5668 } 5669 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5670 } else { 5671 jlong secs = time / NANOSECS_PER_SEC; 5672 if (secs >= MAX_SECS) { 5673 absTime->tv_sec = max_secs; 5674 absTime->tv_nsec = 0; 5675 } else { 5676 absTime->tv_sec = now.tv_sec + secs; 5677 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5678 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5679 absTime->tv_nsec -= NANOSECS_PER_SEC; 5680 ++absTime->tv_sec; // note: this must be <= max_secs 5681 } 5682 } 5683 } 5684 } else { 5685 // must be relative using monotonic clock 5686 struct timespec now; 5687 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5688 assert_status(status == 0, status, "clock_gettime"); 5689 max_secs = now.tv_sec + MAX_SECS; 5690 jlong secs = time / NANOSECS_PER_SEC; 5691 if (secs >= MAX_SECS) { 5692 absTime->tv_sec = max_secs; 5693 absTime->tv_nsec = 0; 5694 } else { 5695 absTime->tv_sec = now.tv_sec + secs; 5696 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5697 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5698 absTime->tv_nsec -= NANOSECS_PER_SEC; 5699 ++absTime->tv_sec; // note: this must be <= max_secs 5700 } 5701 } 5702 } 5703 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5704 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5705 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5706 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5707 } 5708 5709 void Parker::park(bool isAbsolute, jlong time) { 5710 // Ideally we'd do something useful while spinning, such 5711 // as calling unpackTime(). 5712 5713 // Optional fast-path check: 5714 // Return immediately if a permit is available. 5715 // We depend on Atomic::xchg() having full barrier semantics 5716 // since we are doing a lock-free update to _counter. 5717 if (Atomic::xchg(0, &_counter) > 0) return; 5718 5719 Thread* thread = Thread::current(); 5720 assert(thread->is_Java_thread(), "Must be JavaThread"); 5721 JavaThread *jt = (JavaThread *)thread; 5722 5723 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5724 // Check interrupt before trying to wait 5725 if (Thread::is_interrupted(thread, false)) { 5726 return; 5727 } 5728 5729 // Next, demultiplex/decode time arguments 5730 timespec absTime; 5731 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all 5732 return; 5733 } 5734 if (time > 0) { 5735 unpackTime(&absTime, isAbsolute, time); 5736 } 5737 5738 5739 // Enter safepoint region 5740 // Beware of deadlocks such as 6317397. 5741 // The per-thread Parker:: mutex is a classic leaf-lock. 5742 // In particular a thread must never block on the Threads_lock while 5743 // holding the Parker:: mutex. If safepoints are pending both the 5744 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5745 ThreadBlockInVM tbivm(jt); 5746 5747 // Don't wait if cannot get lock since interference arises from 5748 // unblocking. Also. check interrupt before trying wait 5749 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5750 return; 5751 } 5752 5753 int status ; 5754 if (_counter > 0) { // no wait needed 5755 _counter = 0; 5756 status = pthread_mutex_unlock(_mutex); 5757 assert (status == 0, "invariant") ; 5758 // Paranoia to ensure our locked and lock-free paths interact 5759 // correctly with each other and Java-level accesses. 5760 OrderAccess::fence(); 5761 return; 5762 } 5763 5764 #ifdef ASSERT 5765 // Don't catch signals while blocked; let the running threads have the signals. 5766 // (This allows a debugger to break into the running thread.) 5767 sigset_t oldsigs; 5768 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5769 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5770 #endif 5771 5772 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5773 jt->set_suspend_equivalent(); 5774 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5775 5776 assert(_cur_index == -1, "invariant"); 5777 if (time == 0) { 5778 _cur_index = REL_INDEX; // arbitrary choice when not timed 5779 status = pthread_cond_wait (&_cond[_cur_index], _mutex) ; 5780 } else { 5781 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5782 status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ; 5783 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5784 pthread_cond_destroy (&_cond[_cur_index]) ; 5785 pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5786 } 5787 } 5788 _cur_index = -1; 5789 assert_status(status == 0 || status == EINTR || 5790 status == ETIME || status == ETIMEDOUT, 5791 status, "cond_timedwait"); 5792 5793 #ifdef ASSERT 5794 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5795 #endif 5796 5797 _counter = 0 ; 5798 status = pthread_mutex_unlock(_mutex) ; 5799 assert_status(status == 0, status, "invariant") ; 5800 // Paranoia to ensure our locked and lock-free paths interact 5801 // correctly with each other and Java-level accesses. 5802 OrderAccess::fence(); 5803 5804 // If externally suspended while waiting, re-suspend 5805 if (jt->handle_special_suspend_equivalent_condition()) { 5806 jt->java_suspend_self(); 5807 } 5808 } 5809 5810 void Parker::unpark() { 5811 int s, status ; 5812 status = pthread_mutex_lock(_mutex); 5813 assert (status == 0, "invariant") ; 5814 s = _counter; 5815 _counter = 1; 5816 if (s < 1) { 5817 // thread might be parked 5818 if (_cur_index != -1) { 5819 // thread is definitely parked 5820 if (WorkAroundNPTLTimedWaitHang) { 5821 status = pthread_cond_signal (&_cond[_cur_index]); 5822 assert (status == 0, "invariant"); 5823 status = pthread_mutex_unlock(_mutex); 5824 assert (status == 0, "invariant"); 5825 } else { 5826 status = pthread_mutex_unlock(_mutex); 5827 assert (status == 0, "invariant"); 5828 status = pthread_cond_signal (&_cond[_cur_index]); 5829 assert (status == 0, "invariant"); 5830 } 5831 } else { 5832 pthread_mutex_unlock(_mutex); 5833 assert (status == 0, "invariant") ; 5834 } 5835 } else { 5836 pthread_mutex_unlock(_mutex); 5837 assert (status == 0, "invariant") ; 5838 } 5839 } 5840 5841 5842 extern char** environ; 5843 5844 #ifndef __NR_fork 5845 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5846 #endif 5847 5848 #ifndef __NR_execve 5849 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 5850 #endif 5851 5852 // Run the specified command in a separate process. Return its exit value, 5853 // or -1 on failure (e.g. can't fork a new process). 5854 // Unlike system(), this function can be called from signal handler. It 5855 // doesn't block SIGINT et al. 5856 int os::fork_and_exec(char* cmd) { 5857 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5858 5859 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5860 // pthread_atfork handlers and reset pthread library. All we need is a 5861 // separate process to execve. Make a direct syscall to fork process. 5862 // On IA64 there's no fork syscall, we have to use fork() and hope for 5863 // the best... 5864 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5865 IA64_ONLY(fork();) 5866 5867 if (pid < 0) { 5868 // fork failed 5869 return -1; 5870 5871 } else if (pid == 0) { 5872 // child process 5873 5874 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5875 // first to kill every thread on the thread list. Because this list is 5876 // not reset by fork() (see notes above), execve() will instead kill 5877 // every thread in the parent process. We know this is the only thread 5878 // in the new process, so make a system call directly. 5879 // IA64 should use normal execve() from glibc to match the glibc fork() 5880 // above. 5881 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5882 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5883 5884 // execve failed 5885 _exit(-1); 5886 5887 } else { 5888 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5889 // care about the actual exit code, for now. 5890 5891 int status; 5892 5893 // Wait for the child process to exit. This returns immediately if 5894 // the child has already exited. */ 5895 while (waitpid(pid, &status, 0) < 0) { 5896 switch (errno) { 5897 case ECHILD: return 0; 5898 case EINTR: break; 5899 default: return -1; 5900 } 5901 } 5902 5903 if (WIFEXITED(status)) { 5904 // The child exited normally; get its exit code. 5905 return WEXITSTATUS(status); 5906 } else if (WIFSIGNALED(status)) { 5907 // The child exited because of a signal 5908 // The best value to return is 0x80 + signal number, 5909 // because that is what all Unix shells do, and because 5910 // it allows callers to distinguish between process exit and 5911 // process death by signal. 5912 return 0x80 + WTERMSIG(status); 5913 } else { 5914 // Unknown exit code; pass it through 5915 return status; 5916 } 5917 } 5918 } 5919 5920 // is_headless_jre() 5921 // 5922 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 5923 // in order to report if we are running in a headless jre 5924 // 5925 // Since JDK8 xawt/libmawt.so was moved into the same directory 5926 // as libawt.so, and renamed libawt_xawt.so 5927 // 5928 bool os::is_headless_jre() { 5929 struct stat statbuf; 5930 char buf[MAXPATHLEN]; 5931 char libmawtpath[MAXPATHLEN]; 5932 const char *xawtstr = "/xawt/libmawt.so"; 5933 const char *new_xawtstr = "/libawt_xawt.so"; 5934 char *p; 5935 5936 // Get path to libjvm.so 5937 os::jvm_path(buf, sizeof(buf)); 5938 5939 // Get rid of libjvm.so 5940 p = strrchr(buf, '/'); 5941 if (p == NULL) return false; 5942 else *p = '\0'; 5943 5944 // Get rid of client or server 5945 p = strrchr(buf, '/'); 5946 if (p == NULL) return false; 5947 else *p = '\0'; 5948 5949 // check xawt/libmawt.so 5950 strcpy(libmawtpath, buf); 5951 strcat(libmawtpath, xawtstr); 5952 if (::stat(libmawtpath, &statbuf) == 0) return false; 5953 5954 // check libawt_xawt.so 5955 strcpy(libmawtpath, buf); 5956 strcat(libmawtpath, new_xawtstr); 5957 if (::stat(libmawtpath, &statbuf) == 0) return false; 5958 5959 return true; 5960 } 5961 5962 // Get the default path to the core file 5963 // Returns the length of the string 5964 int os::get_core_path(char* buffer, size_t bufferSize) { 5965 const char* p = get_current_directory(buffer, bufferSize); 5966 5967 if (p == NULL) { 5968 assert(p != NULL, "failed to get current directory"); 5969 return 0; 5970 } 5971 5972 return strlen(buffer); 5973 } 5974 5975 #ifdef JAVASE_EMBEDDED 5976 // 5977 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory. 5978 // 5979 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL; 5980 5981 // ctor 5982 // 5983 MemNotifyThread::MemNotifyThread(int fd): Thread() { 5984 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread"); 5985 _fd = fd; 5986 5987 if (os::create_thread(this, os::os_thread)) { 5988 _memnotify_thread = this; 5989 os::set_priority(this, NearMaxPriority); 5990 os::start_thread(this); 5991 } 5992 } 5993 5994 // Where all the work gets done 5995 // 5996 void MemNotifyThread::run() { 5997 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread"); 5998 5999 // Set up the select arguments 6000 fd_set rfds; 6001 if (_fd != -1) { 6002 FD_ZERO(&rfds); 6003 FD_SET(_fd, &rfds); 6004 } 6005 6006 // Now wait for the mem_notify device to wake up 6007 while (1) { 6008 // Wait for the mem_notify device to signal us.. 6009 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL); 6010 if (rc == -1) { 6011 perror("select!\n"); 6012 break; 6013 } else if (rc) { 6014 //ssize_t free_before = os::available_memory(); 6015 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024); 6016 6017 // The kernel is telling us there is not much memory left... 6018 // try to do something about that 6019 6020 // If we are not already in a GC, try one. 6021 if (!Universe::heap()->is_gc_active()) { 6022 Universe::heap()->collect(GCCause::_allocation_failure); 6023 6024 //ssize_t free_after = os::available_memory(); 6025 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024); 6026 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024); 6027 } 6028 // We might want to do something like the following if we find the GC's are not helping... 6029 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true); 6030 } 6031 } 6032 } 6033 6034 // 6035 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it. 6036 // 6037 void MemNotifyThread::start() { 6038 int fd; 6039 fd = open ("/dev/mem_notify", O_RDONLY, 0); 6040 if (fd < 0) { 6041 return; 6042 } 6043 6044 if (memnotify_thread() == NULL) { 6045 new MemNotifyThread(fd); 6046 } 6047 } 6048 6049 #endif // JAVASE_EMBEDDED 6050 6051 6052 /////////////// Unit tests /////////////// 6053 6054 #ifndef PRODUCT 6055 6056 #define test_log(...) \ 6057 do {\ 6058 if (VerboseInternalVMTests) { \ 6059 tty->print_cr(__VA_ARGS__); \ 6060 tty->flush(); \ 6061 }\ 6062 } while (false) 6063 6064 class TestReserveMemorySpecial : AllStatic { 6065 public: 6066 static void small_page_write(void* addr, size_t size) { 6067 size_t page_size = os::vm_page_size(); 6068 6069 char* end = (char*)addr + size; 6070 for (char* p = (char*)addr; p < end; p += page_size) { 6071 *p = 1; 6072 } 6073 } 6074 6075 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6076 if (!UseHugeTLBFS) { 6077 return; 6078 } 6079 6080 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6081 6082 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6083 6084 if (addr != NULL) { 6085 small_page_write(addr, size); 6086 6087 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6088 } 6089 } 6090 6091 static void test_reserve_memory_special_huge_tlbfs_only() { 6092 if (!UseHugeTLBFS) { 6093 return; 6094 } 6095 6096 size_t lp = os::large_page_size(); 6097 6098 for (size_t size = lp; size <= lp * 10; size += lp) { 6099 test_reserve_memory_special_huge_tlbfs_only(size); 6100 } 6101 } 6102 6103 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) { 6104 if (!UseHugeTLBFS) { 6105 return; 6106 } 6107 6108 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")", 6109 size, alignment); 6110 6111 assert(size >= os::large_page_size(), "Incorrect input to test"); 6112 6113 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6114 6115 if (addr != NULL) { 6116 small_page_write(addr, size); 6117 6118 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6119 } 6120 } 6121 6122 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) { 6123 size_t lp = os::large_page_size(); 6124 size_t ag = os::vm_allocation_granularity(); 6125 6126 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6127 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment); 6128 } 6129 } 6130 6131 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6132 size_t lp = os::large_page_size(); 6133 size_t ag = os::vm_allocation_granularity(); 6134 6135 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp); 6136 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag); 6137 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2); 6138 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2); 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 - ag); 6141 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2); 6142 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10); 6143 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2); 6144 } 6145 6146 static void test_reserve_memory_special_huge_tlbfs() { 6147 if (!UseHugeTLBFS) { 6148 return; 6149 } 6150 6151 test_reserve_memory_special_huge_tlbfs_only(); 6152 test_reserve_memory_special_huge_tlbfs_mixed(); 6153 } 6154 6155 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6156 if (!UseSHM) { 6157 return; 6158 } 6159 6160 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6161 6162 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6163 6164 if (addr != NULL) { 6165 assert(is_ptr_aligned(addr, alignment), "Check"); 6166 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6167 6168 small_page_write(addr, size); 6169 6170 os::Linux::release_memory_special_shm(addr, size); 6171 } 6172 } 6173 6174 static void test_reserve_memory_special_shm() { 6175 size_t lp = os::large_page_size(); 6176 size_t ag = os::vm_allocation_granularity(); 6177 6178 for (size_t size = ag; size < lp * 3; size += ag) { 6179 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6180 test_reserve_memory_special_shm(size, alignment); 6181 } 6182 } 6183 } 6184 6185 static void test() { 6186 test_reserve_memory_special_huge_tlbfs(); 6187 test_reserve_memory_special_shm(); 6188 } 6189 }; 6190 6191 void TestReserveMemorySpecial_test() { 6192 TestReserveMemorySpecial::test(); 6193 } 6194 6195 #endif