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_linux.inline.hpp" 40 #include "os_share_linux.hpp" 41 #include "prims/jniFastGetField.hpp" 42 #include "prims/jvm.h" 43 #include "prims/jvm_misc.hpp" 44 #include "runtime/arguments.hpp" 45 #include "runtime/atomic.inline.hpp" 46 #include "runtime/extendedPC.hpp" 47 #include "runtime/globals.hpp" 48 #include "runtime/interfaceSupport.hpp" 49 #include "runtime/init.hpp" 50 #include "runtime/java.hpp" 51 #include "runtime/javaCalls.hpp" 52 #include "runtime/mutexLocker.hpp" 53 #include "runtime/objectMonitor.hpp" 54 #include "runtime/orderAccess.inline.hpp" 55 #include "runtime/osThread.hpp" 56 #include "runtime/perfMemory.hpp" 57 #include "runtime/sharedRuntime.hpp" 58 #include "runtime/statSampler.hpp" 59 #include "runtime/stubRoutines.hpp" 60 #include "runtime/thread.inline.hpp" 61 #include "runtime/threadCritical.hpp" 62 #include "runtime/timer.hpp" 63 #include "services/attachListener.hpp" 64 #include "services/memTracker.hpp" 65 #include "services/runtimeService.hpp" 66 #include "utilities/decoder.hpp" 67 #include "utilities/defaultStream.hpp" 68 #include "utilities/events.hpp" 69 #include "utilities/elfFile.hpp" 70 #include "utilities/growableArray.hpp" 71 #include "utilities/macros.hpp" 72 #include "utilities/vmError.hpp" 73 74 // put OS-includes here 75 # include <sys/types.h> 76 # include <sys/mman.h> 77 # include <sys/stat.h> 78 # include <sys/select.h> 79 # include <pthread.h> 80 # include <signal.h> 81 # include <errno.h> 82 # include <dlfcn.h> 83 # include <stdio.h> 84 # include <unistd.h> 85 # include <sys/resource.h> 86 # include <pthread.h> 87 # include <sys/stat.h> 88 # include <sys/time.h> 89 # include <sys/times.h> 90 # include <sys/utsname.h> 91 # include <sys/socket.h> 92 # include <sys/wait.h> 93 # include <pwd.h> 94 # include <poll.h> 95 # include <semaphore.h> 96 # include <fcntl.h> 97 # include <string.h> 98 # include <syscall.h> 99 # include <sys/sysinfo.h> 100 # include <gnu/libc-version.h> 101 # include <sys/ipc.h> 102 # include <sys/shm.h> 103 # include <link.h> 104 # include <stdint.h> 105 # include <inttypes.h> 106 # include <sys/ioctl.h> 107 108 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 109 110 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling 111 // getrusage() is prepared to handle the associated failure. 112 #ifndef RUSAGE_THREAD 113 #define RUSAGE_THREAD (1) /* only the calling thread */ 114 #endif 115 116 #define MAX_PATH (2 * K) 117 118 #define MAX_SECS 100000000 119 120 // for timer info max values which include all bits 121 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 122 123 #define LARGEPAGES_BIT (1 << 6) 124 //////////////////////////////////////////////////////////////////////////////// 125 // global variables 126 julong os::Linux::_physical_memory = 0; 127 128 address os::Linux::_initial_thread_stack_bottom = NULL; 129 uintptr_t os::Linux::_initial_thread_stack_size = 0; 130 131 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 132 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 133 int (*os::Linux::_pthread_setname_np)(pthread_t, const char*) = NULL; 134 Mutex* os::Linux::_createThread_lock = NULL; 135 pthread_t os::Linux::_main_thread; 136 int os::Linux::_page_size = -1; 137 const int os::Linux::_vm_default_page_size = (8 * K); 138 bool os::Linux::_is_floating_stack = false; 139 bool os::Linux::_is_NPTL = false; 140 bool os::Linux::_supports_fast_thread_cpu_time = false; 141 const char * os::Linux::_glibc_version = NULL; 142 const char * os::Linux::_libpthread_version = NULL; 143 pthread_condattr_t os::Linux::_condattr[1]; 144 145 static jlong initial_time_count=0; 146 147 static int clock_tics_per_sec = 100; 148 149 // For diagnostics to print a message once. see run_periodic_checks 150 static sigset_t check_signal_done; 151 static bool check_signals = true; 152 153 static pid_t _initial_pid = 0; 154 155 // Signal number used to suspend/resume a thread 156 157 // do not use any signal number less than SIGSEGV, see 4355769 158 static int SR_signum = SIGUSR2; 159 sigset_t SR_sigset; 160 161 // Used to protect dlsym() calls 162 static pthread_mutex_t dl_mutex; 163 164 // Declarations 165 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time); 166 167 // utility functions 168 169 static int SR_initialize(); 170 171 julong os::available_memory() { 172 return Linux::available_memory(); 173 } 174 175 julong os::Linux::available_memory() { 176 // values in struct sysinfo are "unsigned long" 177 struct sysinfo si; 178 sysinfo(&si); 179 180 return (julong)si.freeram * si.mem_unit; 181 } 182 183 julong os::physical_memory() { 184 return Linux::physical_memory(); 185 } 186 187 //////////////////////////////////////////////////////////////////////////////// 188 // environment support 189 190 bool os::getenv(const char* name, char* buf, int len) { 191 const char* val = ::getenv(name); 192 if (val != NULL && strlen(val) < (size_t)len) { 193 strcpy(buf, val); 194 return true; 195 } 196 if (len > 0) buf[0] = 0; // return a null string 197 return false; 198 } 199 200 201 // Return true if user is running as root. 202 203 bool os::have_special_privileges() { 204 static bool init = false; 205 static bool privileges = false; 206 if (!init) { 207 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 208 init = true; 209 } 210 return privileges; 211 } 212 213 214 #ifndef SYS_gettid 215 // i386: 224, ia64: 1105, amd64: 186, sparc 143 216 #ifdef __ia64__ 217 #define SYS_gettid 1105 218 #elif __i386__ 219 #define SYS_gettid 224 220 #elif __amd64__ 221 #define SYS_gettid 186 222 #elif __sparc__ 223 #define SYS_gettid 143 224 #else 225 #error define gettid for the arch 226 #endif 227 #endif 228 229 // Cpu architecture string 230 #if defined(ZERO) 231 static char cpu_arch[] = ZERO_LIBARCH; 232 #elif defined(IA64) 233 static char cpu_arch[] = "ia64"; 234 #elif defined(IA32) 235 static char cpu_arch[] = "i386"; 236 #elif defined(AMD64) 237 static char cpu_arch[] = "amd64"; 238 #elif defined(ARM) 239 static char cpu_arch[] = "arm"; 240 #elif defined(PPC32) 241 static char cpu_arch[] = "ppc"; 242 #elif defined(PPC64) 243 static char cpu_arch[] = "ppc64"; 244 #elif defined(SPARC) 245 #ifdef _LP64 246 static char cpu_arch[] = "sparcv9"; 247 #else 248 static char cpu_arch[] = "sparc"; 249 #endif 250 #else 251 #error Add appropriate cpu_arch setting 252 #endif 253 254 255 // pid_t gettid() 256 // 257 // Returns the kernel thread id of the currently running thread. Kernel 258 // thread id is used to access /proc. 259 // 260 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 261 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 262 // 263 pid_t os::Linux::gettid() { 264 int rslt = syscall(SYS_gettid); 265 if (rslt == -1) { 266 // old kernel, no NPTL support 267 return getpid(); 268 } else { 269 return (pid_t)rslt; 270 } 271 } 272 273 // Most versions of linux have a bug where the number of processors are 274 // determined by looking at the /proc file system. In a chroot environment, 275 // the system call returns 1. This causes the VM to act as if it is 276 // a single processor and elide locking (see is_MP() call). 277 static bool unsafe_chroot_detected = false; 278 static const char *unstable_chroot_error = "/proc file system not found.\n" 279 "Java may be unstable running multithreaded in a chroot " 280 "environment on Linux when /proc filesystem is not mounted."; 281 282 void os::Linux::initialize_system_info() { 283 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 284 if (processor_count() == 1) { 285 pid_t pid = os::Linux::gettid(); 286 char fname[32]; 287 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 288 FILE *fp = fopen(fname, "r"); 289 if (fp == NULL) { 290 unsafe_chroot_detected = true; 291 } else { 292 fclose(fp); 293 } 294 } 295 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 296 assert(processor_count() > 0, "linux error"); 297 } 298 299 void os::init_system_properties_values() { 300 // The next steps are taken in the product version: 301 // 302 // Obtain the JAVA_HOME value from the location of libjvm.so. 303 // This library should be located at: 304 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 305 // 306 // If "/jre/lib/" appears at the right place in the path, then we 307 // assume libjvm.so is installed in a JDK and we use this path. 308 // 309 // Otherwise exit with message: "Could not create the Java virtual machine." 310 // 311 // The following extra steps are taken in the debugging version: 312 // 313 // If "/jre/lib/" does NOT appear at the right place in the path 314 // instead of exit check for $JAVA_HOME environment variable. 315 // 316 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 317 // then we append a fake suffix "hotspot/libjvm.so" to this path so 318 // it looks like libjvm.so is installed there 319 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 320 // 321 // Otherwise exit. 322 // 323 // Important note: if the location of libjvm.so changes this 324 // code needs to be changed accordingly. 325 326 // See ld(1): 327 // The linker uses the following search paths to locate required 328 // shared libraries: 329 // 1: ... 330 // ... 331 // 7: The default directories, normally /lib and /usr/lib. 332 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 333 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 334 #else 335 #define DEFAULT_LIBPATH "/lib:/usr/lib" 336 #endif 337 338 // Base path of extensions installed on the system. 339 #define SYS_EXT_DIR "/usr/java/packages" 340 #define EXTENSIONS_DIR "/lib/ext" 341 342 // Buffer that fits several sprintfs. 343 // Note that the space for the colon and the trailing null are provided 344 // by the nulls included by the sizeof operator. 345 const size_t bufsize = 346 MAX2((size_t)MAXPATHLEN, // For dll_dir & friends. 347 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR)); // extensions dir 348 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 349 350 // sysclasspath, java_home, dll_dir 351 { 352 char *pslash; 353 os::jvm_path(buf, bufsize); 354 355 // Found the full path to libjvm.so. 356 // Now cut the path to <java_home>/jre if we can. 357 pslash = strrchr(buf, '/'); 358 if (pslash != NULL) { 359 *pslash = '\0'; // Get rid of /libjvm.so. 360 } 361 pslash = strrchr(buf, '/'); 362 if (pslash != NULL) { 363 *pslash = '\0'; // Get rid of /{client|server|hotspot}. 364 } 365 Arguments::set_dll_dir(buf); 366 367 if (pslash != NULL) { 368 pslash = strrchr(buf, '/'); 369 if (pslash != NULL) { 370 *pslash = '\0'; // Get rid of /<arch>. 371 pslash = strrchr(buf, '/'); 372 if (pslash != NULL) { 373 *pslash = '\0'; // Get rid of /lib. 374 } 375 } 376 } 377 Arguments::set_java_home(buf); 378 set_boot_path('/', ':'); 379 } 380 381 // Where to look for native libraries. 382 // 383 // Note: Due to a legacy implementation, most of the library path 384 // is set in the launcher. This was to accomodate linking restrictions 385 // on legacy Linux implementations (which are no longer supported). 386 // Eventually, all the library path setting will be done here. 387 // 388 // However, to prevent the proliferation of improperly built native 389 // libraries, the new path component /usr/java/packages is added here. 390 // Eventually, all the library path setting will be done here. 391 { 392 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It 393 // should always exist (until the legacy problem cited above is 394 // addressed). 395 const char *v = ::getenv("LD_LIBRARY_PATH"); 396 const char *v_colon = ":"; 397 if (v == NULL) { v = ""; v_colon = ""; } 398 // That's +1 for the colon and +1 for the trailing '\0'. 399 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char, 400 strlen(v) + 1 + 401 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1, 402 mtInternal); 403 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch); 404 Arguments::set_library_path(ld_library_path); 405 FREE_C_HEAP_ARRAY(char, ld_library_path); 406 } 407 408 // Extensions directories. 409 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home()); 410 Arguments::set_ext_dirs(buf); 411 412 FREE_C_HEAP_ARRAY(char, buf); 413 414 #undef DEFAULT_LIBPATH 415 #undef SYS_EXT_DIR 416 #undef EXTENSIONS_DIR 417 } 418 419 //////////////////////////////////////////////////////////////////////////////// 420 // breakpoint support 421 422 void os::breakpoint() { 423 BREAKPOINT; 424 } 425 426 extern "C" void breakpoint() { 427 // use debugger to set breakpoint here 428 } 429 430 //////////////////////////////////////////////////////////////////////////////// 431 // signal support 432 433 debug_only(static bool signal_sets_initialized = false); 434 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 435 436 bool os::Linux::is_sig_ignored(int sig) { 437 struct sigaction oact; 438 sigaction(sig, (struct sigaction*)NULL, &oact); 439 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 440 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 441 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) { 442 return true; 443 } else { 444 return false; 445 } 446 } 447 448 void os::Linux::signal_sets_init() { 449 // Should also have an assertion stating we are still single-threaded. 450 assert(!signal_sets_initialized, "Already initialized"); 451 // Fill in signals that are necessarily unblocked for all threads in 452 // the VM. Currently, we unblock the following signals: 453 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 454 // by -Xrs (=ReduceSignalUsage)); 455 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 456 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 457 // the dispositions or masks wrt these signals. 458 // Programs embedding the VM that want to use the above signals for their 459 // own purposes must, at this time, use the "-Xrs" option to prevent 460 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 461 // (See bug 4345157, and other related bugs). 462 // In reality, though, unblocking these signals is really a nop, since 463 // these signals are not blocked by default. 464 sigemptyset(&unblocked_sigs); 465 sigemptyset(&allowdebug_blocked_sigs); 466 sigaddset(&unblocked_sigs, SIGILL); 467 sigaddset(&unblocked_sigs, SIGSEGV); 468 sigaddset(&unblocked_sigs, SIGBUS); 469 sigaddset(&unblocked_sigs, SIGFPE); 470 #if defined(PPC64) 471 sigaddset(&unblocked_sigs, SIGTRAP); 472 #endif 473 sigaddset(&unblocked_sigs, SR_signum); 474 475 if (!ReduceSignalUsage) { 476 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 477 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 478 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 479 } 480 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 481 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 482 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 483 } 484 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 485 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 486 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 487 } 488 } 489 // Fill in signals that are blocked by all but the VM thread. 490 sigemptyset(&vm_sigs); 491 if (!ReduceSignalUsage) { 492 sigaddset(&vm_sigs, BREAK_SIGNAL); 493 } 494 debug_only(signal_sets_initialized = true); 495 496 } 497 498 // These are signals that are unblocked while a thread is running Java. 499 // (For some reason, they get blocked by default.) 500 sigset_t* os::Linux::unblocked_signals() { 501 assert(signal_sets_initialized, "Not initialized"); 502 return &unblocked_sigs; 503 } 504 505 // These are the signals that are blocked while a (non-VM) thread is 506 // running Java. Only the VM thread handles these signals. 507 sigset_t* os::Linux::vm_signals() { 508 assert(signal_sets_initialized, "Not initialized"); 509 return &vm_sigs; 510 } 511 512 // These are signals that are blocked during cond_wait to allow debugger in 513 sigset_t* os::Linux::allowdebug_blocked_signals() { 514 assert(signal_sets_initialized, "Not initialized"); 515 return &allowdebug_blocked_sigs; 516 } 517 518 void os::Linux::hotspot_sigmask(Thread* thread) { 519 520 //Save caller's signal mask before setting VM signal mask 521 sigset_t caller_sigmask; 522 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 523 524 OSThread* osthread = thread->osthread(); 525 osthread->set_caller_sigmask(caller_sigmask); 526 527 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 528 529 if (!ReduceSignalUsage) { 530 if (thread->is_VM_thread()) { 531 // Only the VM thread handles BREAK_SIGNAL ... 532 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 533 } else { 534 // ... all other threads block BREAK_SIGNAL 535 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 536 } 537 } 538 } 539 540 ////////////////////////////////////////////////////////////////////////////// 541 // detecting pthread library 542 543 void os::Linux::libpthread_init() { 544 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 545 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 546 // generic name for earlier versions. 547 // Define macros here so we can build HotSpot on old systems. 548 #ifndef _CS_GNU_LIBC_VERSION 549 #define _CS_GNU_LIBC_VERSION 2 550 #endif 551 #ifndef _CS_GNU_LIBPTHREAD_VERSION 552 #define _CS_GNU_LIBPTHREAD_VERSION 3 553 #endif 554 555 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 556 if (n > 0) { 557 char *str = (char *)malloc(n, mtInternal); 558 confstr(_CS_GNU_LIBC_VERSION, str, n); 559 os::Linux::set_glibc_version(str); 560 } else { 561 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 562 static char _gnu_libc_version[32]; 563 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 564 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 565 os::Linux::set_glibc_version(_gnu_libc_version); 566 } 567 568 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 569 if (n > 0) { 570 char *str = (char *)malloc(n, mtInternal); 571 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 572 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 573 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 574 // is the case. LinuxThreads has a hard limit on max number of threads. 575 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 576 // On the other hand, NPTL does not have such a limit, sysconf() 577 // will return -1 and errno is not changed. Check if it is really NPTL. 578 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 579 strstr(str, "NPTL") && 580 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 581 free(str); 582 os::Linux::set_libpthread_version("linuxthreads"); 583 } else { 584 os::Linux::set_libpthread_version(str); 585 } 586 } else { 587 // glibc before 2.3.2 only has LinuxThreads. 588 os::Linux::set_libpthread_version("linuxthreads"); 589 } 590 591 if (strstr(libpthread_version(), "NPTL")) { 592 os::Linux::set_is_NPTL(); 593 } else { 594 os::Linux::set_is_LinuxThreads(); 595 } 596 597 // LinuxThreads have two flavors: floating-stack mode, which allows variable 598 // stack size; and fixed-stack mode. NPTL is always floating-stack. 599 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 600 os::Linux::set_is_floating_stack(); 601 } 602 } 603 604 ///////////////////////////////////////////////////////////////////////////// 605 // thread stack 606 607 // Force Linux kernel to expand current thread stack. If "bottom" is close 608 // to the stack guard, caller should block all signals. 609 // 610 // MAP_GROWSDOWN: 611 // A special mmap() flag that is used to implement thread stacks. It tells 612 // kernel that the memory region should extend downwards when needed. This 613 // allows early versions of LinuxThreads to only mmap the first few pages 614 // when creating a new thread. Linux kernel will automatically expand thread 615 // stack as needed (on page faults). 616 // 617 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 618 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 619 // region, it's hard to tell if the fault is due to a legitimate stack 620 // access or because of reading/writing non-exist memory (e.g. buffer 621 // overrun). As a rule, if the fault happens below current stack pointer, 622 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 623 // application (see Linux kernel fault.c). 624 // 625 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 626 // stack overflow detection. 627 // 628 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 629 // not use this flag. However, the stack of initial thread is not created 630 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 631 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 632 // and then attach the thread to JVM. 633 // 634 // To get around the problem and allow stack banging on Linux, we need to 635 // manually expand thread stack after receiving the SIGSEGV. 636 // 637 // There are two ways to expand thread stack to address "bottom", we used 638 // both of them in JVM before 1.5: 639 // 1. adjust stack pointer first so that it is below "bottom", and then 640 // touch "bottom" 641 // 2. mmap() the page in question 642 // 643 // Now alternate signal stack is gone, it's harder to use 2. For instance, 644 // if current sp is already near the lower end of page 101, and we need to 645 // call mmap() to map page 100, it is possible that part of the mmap() frame 646 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 647 // That will destroy the mmap() frame and cause VM to crash. 648 // 649 // The following code works by adjusting sp first, then accessing the "bottom" 650 // page to force a page fault. Linux kernel will then automatically expand the 651 // stack mapping. 652 // 653 // _expand_stack_to() assumes its frame size is less than page size, which 654 // should always be true if the function is not inlined. 655 656 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 657 #define NOINLINE 658 #else 659 #define NOINLINE __attribute__ ((noinline)) 660 #endif 661 662 static void _expand_stack_to(address bottom) NOINLINE; 663 664 static void _expand_stack_to(address bottom) { 665 address sp; 666 size_t size; 667 volatile char *p; 668 669 // Adjust bottom to point to the largest address within the same page, it 670 // gives us a one-page buffer if alloca() allocates slightly more memory. 671 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 672 bottom += os::Linux::page_size() - 1; 673 674 // sp might be slightly above current stack pointer; if that's the case, we 675 // will alloca() a little more space than necessary, which is OK. Don't use 676 // os::current_stack_pointer(), as its result can be slightly below current 677 // stack pointer, causing us to not alloca enough to reach "bottom". 678 sp = (address)&sp; 679 680 if (sp > bottom) { 681 size = sp - bottom; 682 p = (volatile char *)alloca(size); 683 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 684 p[0] = '\0'; 685 } 686 } 687 688 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 689 assert(t!=NULL, "just checking"); 690 assert(t->osthread()->expanding_stack(), "expand should be set"); 691 assert(t->stack_base() != NULL, "stack_base was not initialized"); 692 693 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 694 sigset_t mask_all, old_sigset; 695 sigfillset(&mask_all); 696 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 697 _expand_stack_to(addr); 698 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 699 return true; 700 } 701 return false; 702 } 703 704 ////////////////////////////////////////////////////////////////////////////// 705 // create new thread 706 707 static address highest_vm_reserved_address(); 708 709 // check if it's safe to start a new thread 710 static bool _thread_safety_check(Thread* thread) { 711 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 712 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 713 // Heap is mmap'ed at lower end of memory space. Thread stacks are 714 // allocated (MAP_FIXED) from high address space. Every thread stack 715 // occupies a fixed size slot (usually 2Mbytes, but user can change 716 // it to other values if they rebuild LinuxThreads). 717 // 718 // Problem with MAP_FIXED is that mmap() can still succeed even part of 719 // the memory region has already been mmap'ed. That means if we have too 720 // many threads and/or very large heap, eventually thread stack will 721 // collide with heap. 722 // 723 // Here we try to prevent heap/stack collision by comparing current 724 // stack bottom with the highest address that has been mmap'ed by JVM 725 // plus a safety margin for memory maps created by native code. 726 // 727 // This feature can be disabled by setting ThreadSafetyMargin to 0 728 // 729 if (ThreadSafetyMargin > 0) { 730 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 731 732 // not safe if our stack extends below the safety margin 733 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 734 } else { 735 return true; 736 } 737 } else { 738 // Floating stack LinuxThreads or NPTL: 739 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 740 // there's not enough space left, pthread_create() will fail. If we come 741 // here, that means enough space has been reserved for stack. 742 return true; 743 } 744 } 745 746 // Thread start routine for all newly created threads 747 static void *java_start(Thread *thread) { 748 // Try to randomize the cache line index of hot stack frames. 749 // This helps when threads of the same stack traces evict each other's 750 // cache lines. The threads can be either from the same JVM instance, or 751 // from different JVM instances. The benefit is especially true for 752 // processors with hyperthreading technology. 753 static int counter = 0; 754 int pid = os::current_process_id(); 755 alloca(((pid ^ counter++) & 7) * 128); 756 757 ThreadLocalStorage::set_thread(thread); 758 759 OSThread* osthread = thread->osthread(); 760 Monitor* sync = osthread->startThread_lock(); 761 762 // non floating stack LinuxThreads needs extra check, see above 763 if (!_thread_safety_check(thread)) { 764 // notify parent thread 765 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 766 osthread->set_state(ZOMBIE); 767 sync->notify_all(); 768 return NULL; 769 } 770 771 // thread_id is kernel thread id (similar to Solaris LWP id) 772 osthread->set_thread_id(os::Linux::gettid()); 773 774 if (UseNUMA) { 775 int lgrp_id = os::numa_get_group_id(); 776 if (lgrp_id != -1) { 777 thread->set_lgrp_id(lgrp_id); 778 } 779 } 780 // initialize signal mask for this thread 781 os::Linux::hotspot_sigmask(thread); 782 783 // initialize floating point control register 784 os::Linux::init_thread_fpu_state(); 785 786 // handshaking with parent thread 787 { 788 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 789 790 // notify parent thread 791 osthread->set_state(INITIALIZED); 792 sync->notify_all(); 793 794 // wait until os::start_thread() 795 while (osthread->get_state() == INITIALIZED) { 796 sync->wait(Mutex::_no_safepoint_check_flag); 797 } 798 } 799 800 // call one more level start routine 801 thread->run(); 802 803 return 0; 804 } 805 806 bool os::create_thread(Thread* thread, ThreadType thr_type, 807 size_t stack_size) { 808 assert(thread->osthread() == NULL, "caller responsible"); 809 810 // Allocate the OSThread object 811 OSThread* osthread = new OSThread(NULL, NULL); 812 if (osthread == NULL) { 813 return false; 814 } 815 816 // set the correct thread state 817 osthread->set_thread_type(thr_type); 818 819 // Initial state is ALLOCATED but not INITIALIZED 820 osthread->set_state(ALLOCATED); 821 822 thread->set_osthread(osthread); 823 824 // init thread attributes 825 pthread_attr_t attr; 826 pthread_attr_init(&attr); 827 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 828 829 // stack size 830 if (os::Linux::supports_variable_stack_size()) { 831 // calculate stack size if it's not specified by caller 832 if (stack_size == 0) { 833 stack_size = os::Linux::default_stack_size(thr_type); 834 835 switch (thr_type) { 836 case os::java_thread: 837 // Java threads use ThreadStackSize which default value can be 838 // changed with the flag -Xss 839 assert(JavaThread::stack_size_at_create() > 0, "this should be set"); 840 stack_size = JavaThread::stack_size_at_create(); 841 break; 842 case os::compiler_thread: 843 if (CompilerThreadStackSize > 0) { 844 stack_size = (size_t)(CompilerThreadStackSize * K); 845 break; 846 } // else fall through: 847 // use VMThreadStackSize if CompilerThreadStackSize is not defined 848 case os::vm_thread: 849 case os::pgc_thread: 850 case os::cgc_thread: 851 case os::watcher_thread: 852 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 853 break; 854 } 855 } 856 857 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 858 pthread_attr_setstacksize(&attr, stack_size); 859 } else { 860 // let pthread_create() pick the default value. 861 } 862 863 // glibc guard page 864 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 865 866 ThreadState state; 867 868 { 869 // Serialize thread creation if we are running with fixed stack LinuxThreads 870 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 871 if (lock) { 872 os::Linux::createThread_lock()->lock_without_safepoint_check(); 873 } 874 875 pthread_t tid; 876 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 877 878 pthread_attr_destroy(&attr); 879 880 if (ret != 0) { 881 if (PrintMiscellaneous && (Verbose || WizardMode)) { 882 perror("pthread_create()"); 883 } 884 // Need to clean up stuff we've allocated so far 885 thread->set_osthread(NULL); 886 delete osthread; 887 if (lock) os::Linux::createThread_lock()->unlock(); 888 return false; 889 } 890 891 // Store pthread info into the OSThread 892 osthread->set_pthread_id(tid); 893 894 // Wait until child thread is either initialized or aborted 895 { 896 Monitor* sync_with_child = osthread->startThread_lock(); 897 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 898 while ((state = osthread->get_state()) == ALLOCATED) { 899 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 900 } 901 } 902 903 if (lock) { 904 os::Linux::createThread_lock()->unlock(); 905 } 906 } 907 908 // Aborted due to thread limit being reached 909 if (state == ZOMBIE) { 910 thread->set_osthread(NULL); 911 delete osthread; 912 return false; 913 } 914 915 // The thread is returned suspended (in state INITIALIZED), 916 // and is started higher up in the call chain 917 assert(state == INITIALIZED, "race condition"); 918 return true; 919 } 920 921 ///////////////////////////////////////////////////////////////////////////// 922 // attach existing thread 923 924 // bootstrap the main thread 925 bool os::create_main_thread(JavaThread* thread) { 926 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 927 return create_attached_thread(thread); 928 } 929 930 bool os::create_attached_thread(JavaThread* thread) { 931 #ifdef ASSERT 932 thread->verify_not_published(); 933 #endif 934 935 // Allocate the OSThread object 936 OSThread* osthread = new OSThread(NULL, NULL); 937 938 if (osthread == NULL) { 939 return false; 940 } 941 942 // Store pthread info into the OSThread 943 osthread->set_thread_id(os::Linux::gettid()); 944 osthread->set_pthread_id(::pthread_self()); 945 946 // initialize floating point control register 947 os::Linux::init_thread_fpu_state(); 948 949 // Initial thread state is RUNNABLE 950 osthread->set_state(RUNNABLE); 951 952 thread->set_osthread(osthread); 953 954 if (UseNUMA) { 955 int lgrp_id = os::numa_get_group_id(); 956 if (lgrp_id != -1) { 957 thread->set_lgrp_id(lgrp_id); 958 } 959 } 960 961 if (os::Linux::is_initial_thread()) { 962 // If current thread is initial thread, its stack is mapped on demand, 963 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 964 // the entire stack region to avoid SEGV in stack banging. 965 // It is also useful to get around the heap-stack-gap problem on SuSE 966 // kernel (see 4821821 for details). We first expand stack to the top 967 // of yellow zone, then enable stack yellow zone (order is significant, 968 // enabling yellow zone first will crash JVM on SuSE Linux), so there 969 // is no gap between the last two virtual memory regions. 970 971 JavaThread *jt = (JavaThread *)thread; 972 address addr = jt->stack_yellow_zone_base(); 973 assert(addr != NULL, "initialization problem?"); 974 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 975 976 osthread->set_expanding_stack(); 977 os::Linux::manually_expand_stack(jt, addr); 978 osthread->clear_expanding_stack(); 979 } 980 981 // initialize signal mask for this thread 982 // and save the caller's signal mask 983 os::Linux::hotspot_sigmask(thread); 984 985 return true; 986 } 987 988 void os::pd_start_thread(Thread* thread) { 989 OSThread * osthread = thread->osthread(); 990 assert(osthread->get_state() != INITIALIZED, "just checking"); 991 Monitor* sync_with_child = osthread->startThread_lock(); 992 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 993 sync_with_child->notify(); 994 } 995 996 // Free Linux resources related to the OSThread 997 void os::free_thread(OSThread* osthread) { 998 assert(osthread != NULL, "osthread not set"); 999 1000 if (Thread::current()->osthread() == osthread) { 1001 // Restore caller's signal mask 1002 sigset_t sigmask = osthread->caller_sigmask(); 1003 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1004 } 1005 1006 delete osthread; 1007 } 1008 1009 ////////////////////////////////////////////////////////////////////////////// 1010 // thread local storage 1011 1012 // Restore the thread pointer if the destructor is called. This is in case 1013 // someone from JNI code sets up a destructor with pthread_key_create to run 1014 // detachCurrentThread on thread death. Unless we restore the thread pointer we 1015 // will hang or crash. When detachCurrentThread is called the key will be set 1016 // to null and we will not be called again. If detachCurrentThread is never 1017 // called we could loop forever depending on the pthread implementation. 1018 static void restore_thread_pointer(void* p) { 1019 Thread* thread = (Thread*) p; 1020 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); 1021 } 1022 1023 int os::allocate_thread_local_storage() { 1024 pthread_key_t key; 1025 int rslt = pthread_key_create(&key, restore_thread_pointer); 1026 assert(rslt == 0, "cannot allocate thread local storage"); 1027 return (int)key; 1028 } 1029 1030 // Note: This is currently not used by VM, as we don't destroy TLS key 1031 // on VM exit. 1032 void os::free_thread_local_storage(int index) { 1033 int rslt = pthread_key_delete((pthread_key_t)index); 1034 assert(rslt == 0, "invalid index"); 1035 } 1036 1037 void os::thread_local_storage_at_put(int index, void* value) { 1038 int rslt = pthread_setspecific((pthread_key_t)index, value); 1039 assert(rslt == 0, "pthread_setspecific failed"); 1040 } 1041 1042 extern "C" Thread* get_thread() { 1043 return ThreadLocalStorage::thread(); 1044 } 1045 1046 ////////////////////////////////////////////////////////////////////////////// 1047 // initial thread 1048 1049 // Check if current thread is the initial thread, similar to Solaris thr_main. 1050 bool os::Linux::is_initial_thread(void) { 1051 char dummy; 1052 // If called before init complete, thread stack bottom will be null. 1053 // Can be called if fatal error occurs before initialization. 1054 if (initial_thread_stack_bottom() == NULL) return false; 1055 assert(initial_thread_stack_bottom() != NULL && 1056 initial_thread_stack_size() != 0, 1057 "os::init did not locate initial thread's stack region"); 1058 if ((address)&dummy >= initial_thread_stack_bottom() && 1059 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) { 1060 return true; 1061 } else { 1062 return false; 1063 } 1064 } 1065 1066 // Find the virtual memory area that contains addr 1067 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1068 FILE *fp = fopen("/proc/self/maps", "r"); 1069 if (fp) { 1070 address low, high; 1071 while (!feof(fp)) { 1072 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1073 if (low <= addr && addr < high) { 1074 if (vma_low) *vma_low = low; 1075 if (vma_high) *vma_high = high; 1076 fclose(fp); 1077 return true; 1078 } 1079 } 1080 for (;;) { 1081 int ch = fgetc(fp); 1082 if (ch == EOF || ch == (int)'\n') break; 1083 } 1084 } 1085 fclose(fp); 1086 } 1087 return false; 1088 } 1089 1090 // Locate initial thread stack. This special handling of initial thread stack 1091 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1092 // bogus value for initial thread. 1093 void os::Linux::capture_initial_stack(size_t max_size) { 1094 // stack size is the easy part, get it from RLIMIT_STACK 1095 size_t stack_size; 1096 struct rlimit rlim; 1097 getrlimit(RLIMIT_STACK, &rlim); 1098 stack_size = rlim.rlim_cur; 1099 1100 // 6308388: a bug in ld.so will relocate its own .data section to the 1101 // lower end of primordial stack; reduce ulimit -s value a little bit 1102 // so we won't install guard page on ld.so's data section. 1103 stack_size -= 2 * page_size(); 1104 1105 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1106 // 7.1, in both cases we will get 2G in return value. 1107 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1108 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1109 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1110 // in case other parts in glibc still assumes 2M max stack size. 1111 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1112 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1113 if (stack_size > 2 * K * K IA64_ONLY(*2)) { 1114 stack_size = 2 * K * K IA64_ONLY(*2); 1115 } 1116 // Try to figure out where the stack base (top) is. This is harder. 1117 // 1118 // When an application is started, glibc saves the initial stack pointer in 1119 // a global variable "__libc_stack_end", which is then used by system 1120 // libraries. __libc_stack_end should be pretty close to stack top. The 1121 // variable is available since the very early days. However, because it is 1122 // a private interface, it could disappear in the future. 1123 // 1124 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1125 // to __libc_stack_end, it is very close to stack top, but isn't the real 1126 // stack top. Note that /proc may not exist if VM is running as a chroot 1127 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1128 // /proc/<pid>/stat could change in the future (though unlikely). 1129 // 1130 // We try __libc_stack_end first. If that doesn't work, look for 1131 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1132 // as a hint, which should work well in most cases. 1133 1134 uintptr_t stack_start; 1135 1136 // try __libc_stack_end first 1137 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1138 if (p && *p) { 1139 stack_start = *p; 1140 } else { 1141 // see if we can get the start_stack field from /proc/self/stat 1142 FILE *fp; 1143 int pid; 1144 char state; 1145 int ppid; 1146 int pgrp; 1147 int session; 1148 int nr; 1149 int tpgrp; 1150 unsigned long flags; 1151 unsigned long minflt; 1152 unsigned long cminflt; 1153 unsigned long majflt; 1154 unsigned long cmajflt; 1155 unsigned long utime; 1156 unsigned long stime; 1157 long cutime; 1158 long cstime; 1159 long prio; 1160 long nice; 1161 long junk; 1162 long it_real; 1163 uintptr_t start; 1164 uintptr_t vsize; 1165 intptr_t rss; 1166 uintptr_t rsslim; 1167 uintptr_t scodes; 1168 uintptr_t ecode; 1169 int i; 1170 1171 // Figure what the primordial thread stack base is. Code is inspired 1172 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1173 // followed by command name surrounded by parentheses, state, etc. 1174 char stat[2048]; 1175 int statlen; 1176 1177 fp = fopen("/proc/self/stat", "r"); 1178 if (fp) { 1179 statlen = fread(stat, 1, 2047, fp); 1180 stat[statlen] = '\0'; 1181 fclose(fp); 1182 1183 // Skip pid and the command string. Note that we could be dealing with 1184 // weird command names, e.g. user could decide to rename java launcher 1185 // to "java 1.4.2 :)", then the stat file would look like 1186 // 1234 (java 1.4.2 :)) R ... ... 1187 // We don't really need to know the command string, just find the last 1188 // occurrence of ")" and then start parsing from there. See bug 4726580. 1189 char * s = strrchr(stat, ')'); 1190 1191 i = 0; 1192 if (s) { 1193 // Skip blank chars 1194 do { s++; } while (s && isspace(*s)); 1195 1196 #define _UFM UINTX_FORMAT 1197 #define _DFM INTX_FORMAT 1198 1199 // 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 1200 // 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 1201 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, 1202 &state, // 3 %c 1203 &ppid, // 4 %d 1204 &pgrp, // 5 %d 1205 &session, // 6 %d 1206 &nr, // 7 %d 1207 &tpgrp, // 8 %d 1208 &flags, // 9 %lu 1209 &minflt, // 10 %lu 1210 &cminflt, // 11 %lu 1211 &majflt, // 12 %lu 1212 &cmajflt, // 13 %lu 1213 &utime, // 14 %lu 1214 &stime, // 15 %lu 1215 &cutime, // 16 %ld 1216 &cstime, // 17 %ld 1217 &prio, // 18 %ld 1218 &nice, // 19 %ld 1219 &junk, // 20 %ld 1220 &it_real, // 21 %ld 1221 &start, // 22 UINTX_FORMAT 1222 &vsize, // 23 UINTX_FORMAT 1223 &rss, // 24 INTX_FORMAT 1224 &rsslim, // 25 UINTX_FORMAT 1225 &scodes, // 26 UINTX_FORMAT 1226 &ecode, // 27 UINTX_FORMAT 1227 &stack_start); // 28 UINTX_FORMAT 1228 } 1229 1230 #undef _UFM 1231 #undef _DFM 1232 1233 if (i != 28 - 2) { 1234 assert(false, "Bad conversion from /proc/self/stat"); 1235 // product mode - assume we are the initial thread, good luck in the 1236 // embedded case. 1237 warning("Can't detect initial thread stack location - bad conversion"); 1238 stack_start = (uintptr_t) &rlim; 1239 } 1240 } else { 1241 // For some reason we can't open /proc/self/stat (for example, running on 1242 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1243 // most cases, so don't abort: 1244 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1245 stack_start = (uintptr_t) &rlim; 1246 } 1247 } 1248 1249 // Now we have a pointer (stack_start) very close to the stack top, the 1250 // next thing to do is to figure out the exact location of stack top. We 1251 // can find out the virtual memory area that contains stack_start by 1252 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1253 // and its upper limit is the real stack top. (again, this would fail if 1254 // running inside chroot, because /proc may not exist.) 1255 1256 uintptr_t stack_top; 1257 address low, high; 1258 if (find_vma((address)stack_start, &low, &high)) { 1259 // success, "high" is the true stack top. (ignore "low", because initial 1260 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1261 stack_top = (uintptr_t)high; 1262 } else { 1263 // failed, likely because /proc/self/maps does not exist 1264 warning("Can't detect initial thread stack location - find_vma failed"); 1265 // best effort: stack_start is normally within a few pages below the real 1266 // stack top, use it as stack top, and reduce stack size so we won't put 1267 // guard page outside stack. 1268 stack_top = stack_start; 1269 stack_size -= 16 * page_size(); 1270 } 1271 1272 // stack_top could be partially down the page so align it 1273 stack_top = align_size_up(stack_top, page_size()); 1274 1275 if (max_size && stack_size > max_size) { 1276 _initial_thread_stack_size = max_size; 1277 } else { 1278 _initial_thread_stack_size = stack_size; 1279 } 1280 1281 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1282 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1283 } 1284 1285 //////////////////////////////////////////////////////////////////////////////// 1286 // time support 1287 1288 // Time since start-up in seconds to a fine granularity. 1289 // Used by VMSelfDestructTimer and the MemProfiler. 1290 double os::elapsedTime() { 1291 1292 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution 1293 } 1294 1295 jlong os::elapsed_counter() { 1296 return javaTimeNanos() - initial_time_count; 1297 } 1298 1299 jlong os::elapsed_frequency() { 1300 return NANOSECS_PER_SEC; // nanosecond resolution 1301 } 1302 1303 bool os::supports_vtime() { return true; } 1304 bool os::enable_vtime() { return false; } 1305 bool os::vtime_enabled() { return false; } 1306 1307 double os::elapsedVTime() { 1308 struct rusage usage; 1309 int retval = getrusage(RUSAGE_THREAD, &usage); 1310 if (retval == 0) { 1311 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); 1312 } else { 1313 // better than nothing, but not much 1314 return elapsedTime(); 1315 } 1316 } 1317 1318 jlong os::javaTimeMillis() { 1319 timeval time; 1320 int status = gettimeofday(&time, NULL); 1321 assert(status != -1, "linux error"); 1322 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1323 } 1324 1325 #ifndef CLOCK_MONOTONIC 1326 #define CLOCK_MONOTONIC (1) 1327 #endif 1328 1329 void os::Linux::clock_init() { 1330 // we do dlopen's in this particular order due to bug in linux 1331 // dynamical loader (see 6348968) leading to crash on exit 1332 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1333 if (handle == NULL) { 1334 handle = dlopen("librt.so", RTLD_LAZY); 1335 } 1336 1337 if (handle) { 1338 int (*clock_getres_func)(clockid_t, struct timespec*) = 1339 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1340 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1341 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1342 if (clock_getres_func && clock_gettime_func) { 1343 // See if monotonic clock is supported by the kernel. Note that some 1344 // early implementations simply return kernel jiffies (updated every 1345 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1346 // for nano time (though the monotonic property is still nice to have). 1347 // It's fixed in newer kernels, however clock_getres() still returns 1348 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1349 // resolution for now. Hopefully as people move to new kernels, this 1350 // won't be a problem. 1351 struct timespec res; 1352 struct timespec tp; 1353 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1354 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1355 // yes, monotonic clock is supported 1356 _clock_gettime = clock_gettime_func; 1357 return; 1358 } else { 1359 // close librt if there is no monotonic clock 1360 dlclose(handle); 1361 } 1362 } 1363 } 1364 warning("No monotonic clock was available - timed services may " \ 1365 "be adversely affected if the time-of-day clock changes"); 1366 } 1367 1368 #ifndef SYS_clock_getres 1369 #if defined(IA32) || defined(AMD64) 1370 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1371 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1372 #else 1373 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1374 #define sys_clock_getres(x,y) -1 1375 #endif 1376 #else 1377 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1378 #endif 1379 1380 void os::Linux::fast_thread_clock_init() { 1381 if (!UseLinuxPosixThreadCPUClocks) { 1382 return; 1383 } 1384 clockid_t clockid; 1385 struct timespec tp; 1386 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1387 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1388 1389 // Switch to using fast clocks for thread cpu time if 1390 // the sys_clock_getres() returns 0 error code. 1391 // Note, that some kernels may support the current thread 1392 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1393 // returned by the pthread_getcpuclockid(). 1394 // If the fast Posix clocks are supported then the sys_clock_getres() 1395 // must return at least tp.tv_sec == 0 which means a resolution 1396 // better than 1 sec. This is extra check for reliability. 1397 1398 if (pthread_getcpuclockid_func && 1399 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1400 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1401 _supports_fast_thread_cpu_time = true; 1402 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1403 } 1404 } 1405 1406 jlong os::javaTimeNanos() { 1407 if (os::supports_monotonic_clock()) { 1408 struct timespec tp; 1409 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1410 assert(status == 0, "gettime error"); 1411 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1412 return result; 1413 } else { 1414 timeval time; 1415 int status = gettimeofday(&time, NULL); 1416 assert(status != -1, "linux error"); 1417 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1418 return 1000 * usecs; 1419 } 1420 } 1421 1422 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1423 if (os::supports_monotonic_clock()) { 1424 info_ptr->max_value = ALL_64_BITS; 1425 1426 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1427 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1428 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1429 } else { 1430 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1431 info_ptr->max_value = ALL_64_BITS; 1432 1433 // gettimeofday is a real time clock so it skips 1434 info_ptr->may_skip_backward = true; 1435 info_ptr->may_skip_forward = true; 1436 } 1437 1438 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1439 } 1440 1441 // Return the real, user, and system times in seconds from an 1442 // arbitrary fixed point in the past. 1443 bool os::getTimesSecs(double* process_real_time, 1444 double* process_user_time, 1445 double* process_system_time) { 1446 struct tms ticks; 1447 clock_t real_ticks = times(&ticks); 1448 1449 if (real_ticks == (clock_t) (-1)) { 1450 return false; 1451 } else { 1452 double ticks_per_second = (double) clock_tics_per_sec; 1453 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1454 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1455 *process_real_time = ((double) real_ticks) / ticks_per_second; 1456 1457 return true; 1458 } 1459 } 1460 1461 1462 char * os::local_time_string(char *buf, size_t buflen) { 1463 struct tm t; 1464 time_t long_time; 1465 time(&long_time); 1466 localtime_r(&long_time, &t); 1467 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1468 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1469 t.tm_hour, t.tm_min, t.tm_sec); 1470 return buf; 1471 } 1472 1473 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1474 return localtime_r(clock, res); 1475 } 1476 1477 //////////////////////////////////////////////////////////////////////////////// 1478 // runtime exit support 1479 1480 // Note: os::shutdown() might be called very early during initialization, or 1481 // called from signal handler. Before adding something to os::shutdown(), make 1482 // sure it is async-safe and can handle partially initialized VM. 1483 void os::shutdown() { 1484 1485 // allow PerfMemory to attempt cleanup of any persistent resources 1486 perfMemory_exit(); 1487 1488 // needs to remove object in file system 1489 AttachListener::abort(); 1490 1491 // flush buffered output, finish log files 1492 ostream_abort(); 1493 1494 // Check for abort hook 1495 abort_hook_t abort_hook = Arguments::abort_hook(); 1496 if (abort_hook != NULL) { 1497 abort_hook(); 1498 } 1499 1500 } 1501 1502 // Note: os::abort() might be called very early during initialization, or 1503 // called from signal handler. Before adding something to os::abort(), make 1504 // sure it is async-safe and can handle partially initialized VM. 1505 void os::abort(bool dump_core) { 1506 os::shutdown(); 1507 if (dump_core) { 1508 #ifndef PRODUCT 1509 fdStream out(defaultStream::output_fd()); 1510 out.print_raw("Current thread is "); 1511 char buf[16]; 1512 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1513 out.print_raw_cr(buf); 1514 out.print_raw_cr("Dumping core ..."); 1515 #endif 1516 ::abort(); // dump core 1517 } 1518 1519 ::exit(1); 1520 } 1521 1522 // Die immediately, no exit hook, no abort hook, no cleanup. 1523 void os::die() { 1524 // _exit() on LinuxThreads only kills current thread 1525 ::abort(); 1526 } 1527 1528 1529 // This method is a copy of JDK's sysGetLastErrorString 1530 // from src/solaris/hpi/src/system_md.c 1531 1532 size_t os::lasterror(char *buf, size_t len) { 1533 if (errno == 0) return 0; 1534 1535 const char *s = ::strerror(errno); 1536 size_t n = ::strlen(s); 1537 if (n >= len) { 1538 n = len - 1; 1539 } 1540 ::strncpy(buf, s, n); 1541 buf[n] = '\0'; 1542 return n; 1543 } 1544 1545 intx os::current_thread_id() { return (intx)pthread_self(); } 1546 int os::current_process_id() { 1547 1548 // Under the old linux thread library, linux gives each thread 1549 // its own process id. Because of this each thread will return 1550 // a different pid if this method were to return the result 1551 // of getpid(2). Linux provides no api that returns the pid 1552 // of the launcher thread for the vm. This implementation 1553 // returns a unique pid, the pid of the launcher thread 1554 // that starts the vm 'process'. 1555 1556 // Under the NPTL, getpid() returns the same pid as the 1557 // launcher thread rather than a unique pid per thread. 1558 // Use gettid() if you want the old pre NPTL behaviour. 1559 1560 // if you are looking for the result of a call to getpid() that 1561 // returns a unique pid for the calling thread, then look at the 1562 // OSThread::thread_id() method in osThread_linux.hpp file 1563 1564 return (int)(_initial_pid ? _initial_pid : getpid()); 1565 } 1566 1567 // DLL functions 1568 1569 const char* os::dll_file_extension() { return ".so"; } 1570 1571 // This must be hard coded because it's the system's temporary 1572 // directory not the java application's temp directory, ala java.io.tmpdir. 1573 const char* os::get_temp_directory() { return "/tmp"; } 1574 1575 static bool file_exists(const char* filename) { 1576 struct stat statbuf; 1577 if (filename == NULL || strlen(filename) == 0) { 1578 return false; 1579 } 1580 return os::stat(filename, &statbuf) == 0; 1581 } 1582 1583 bool os::dll_build_name(char* buffer, size_t buflen, 1584 const char* pname, const char* fname) { 1585 bool retval = false; 1586 // Copied from libhpi 1587 const size_t pnamelen = pname ? strlen(pname) : 0; 1588 1589 // Return error on buffer overflow. 1590 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1591 return retval; 1592 } 1593 1594 if (pnamelen == 0) { 1595 snprintf(buffer, buflen, "lib%s.so", fname); 1596 retval = true; 1597 } else if (strchr(pname, *os::path_separator()) != NULL) { 1598 int n; 1599 char** pelements = split_path(pname, &n); 1600 if (pelements == NULL) { 1601 return false; 1602 } 1603 for (int i = 0; i < n; i++) { 1604 // Really shouldn't be NULL, but check can't hurt 1605 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1606 continue; // skip the empty path values 1607 } 1608 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1609 if (file_exists(buffer)) { 1610 retval = true; 1611 break; 1612 } 1613 } 1614 // release the storage 1615 for (int i = 0; i < n; i++) { 1616 if (pelements[i] != NULL) { 1617 FREE_C_HEAP_ARRAY(char, pelements[i]); 1618 } 1619 } 1620 if (pelements != NULL) { 1621 FREE_C_HEAP_ARRAY(char*, pelements); 1622 } 1623 } else { 1624 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1625 retval = true; 1626 } 1627 return retval; 1628 } 1629 1630 // check if addr is inside libjvm.so 1631 bool os::address_is_in_vm(address addr) { 1632 static address libjvm_base_addr; 1633 Dl_info dlinfo; 1634 1635 if (libjvm_base_addr == NULL) { 1636 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1637 libjvm_base_addr = (address)dlinfo.dli_fbase; 1638 } 1639 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1640 } 1641 1642 if (dladdr((void *)addr, &dlinfo) != 0) { 1643 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1644 } 1645 1646 return false; 1647 } 1648 1649 bool os::dll_address_to_function_name(address addr, char *buf, 1650 int buflen, int *offset) { 1651 // buf is not optional, but offset is optional 1652 assert(buf != NULL, "sanity check"); 1653 1654 Dl_info dlinfo; 1655 1656 if (dladdr((void*)addr, &dlinfo) != 0) { 1657 // see if we have a matching symbol 1658 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1659 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1660 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1661 } 1662 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1663 return true; 1664 } 1665 // no matching symbol so try for just file info 1666 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1667 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1668 buf, buflen, offset, dlinfo.dli_fname)) { 1669 return true; 1670 } 1671 } 1672 } 1673 1674 buf[0] = '\0'; 1675 if (offset != NULL) *offset = -1; 1676 return false; 1677 } 1678 1679 struct _address_to_library_name { 1680 address addr; // input : memory address 1681 size_t buflen; // size of fname 1682 char* fname; // output: library name 1683 address base; // library base addr 1684 }; 1685 1686 static int address_to_library_name_callback(struct dl_phdr_info *info, 1687 size_t size, void *data) { 1688 int i; 1689 bool found = false; 1690 address libbase = NULL; 1691 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1692 1693 // iterate through all loadable segments 1694 for (i = 0; i < info->dlpi_phnum; i++) { 1695 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1696 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1697 // base address of a library is the lowest address of its loaded 1698 // segments. 1699 if (libbase == NULL || libbase > segbase) { 1700 libbase = segbase; 1701 } 1702 // see if 'addr' is within current segment 1703 if (segbase <= d->addr && 1704 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1705 found = true; 1706 } 1707 } 1708 } 1709 1710 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1711 // so dll_address_to_library_name() can fall through to use dladdr() which 1712 // can figure out executable name from argv[0]. 1713 if (found && info->dlpi_name && info->dlpi_name[0]) { 1714 d->base = libbase; 1715 if (d->fname) { 1716 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1717 } 1718 return 1; 1719 } 1720 return 0; 1721 } 1722 1723 bool os::dll_address_to_library_name(address addr, char* buf, 1724 int buflen, int* offset) { 1725 // buf is not optional, but offset is optional 1726 assert(buf != NULL, "sanity check"); 1727 1728 Dl_info dlinfo; 1729 struct _address_to_library_name data; 1730 1731 // There is a bug in old glibc dladdr() implementation that it could resolve 1732 // to wrong library name if the .so file has a base address != NULL. Here 1733 // we iterate through the program headers of all loaded libraries to find 1734 // out which library 'addr' really belongs to. This workaround can be 1735 // removed once the minimum requirement for glibc is moved to 2.3.x. 1736 data.addr = addr; 1737 data.fname = buf; 1738 data.buflen = buflen; 1739 data.base = NULL; 1740 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1741 1742 if (rslt) { 1743 // buf already contains library name 1744 if (offset) *offset = addr - data.base; 1745 return true; 1746 } 1747 if (dladdr((void*)addr, &dlinfo) != 0) { 1748 if (dlinfo.dli_fname != NULL) { 1749 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1750 } 1751 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1752 *offset = addr - (address)dlinfo.dli_fbase; 1753 } 1754 return true; 1755 } 1756 1757 buf[0] = '\0'; 1758 if (offset) *offset = -1; 1759 return false; 1760 } 1761 1762 // Loads .dll/.so and 1763 // in case of error it checks if .dll/.so was built for the 1764 // same architecture as Hotspot is running on 1765 1766 1767 // Remember the stack's state. The Linux dynamic linker will change 1768 // the stack to 'executable' at most once, so we must safepoint only once. 1769 bool os::Linux::_stack_is_executable = false; 1770 1771 // VM operation that loads a library. This is necessary if stack protection 1772 // of the Java stacks can be lost during loading the library. If we 1773 // do not stop the Java threads, they can stack overflow before the stacks 1774 // are protected again. 1775 class VM_LinuxDllLoad: public VM_Operation { 1776 private: 1777 const char *_filename; 1778 char *_ebuf; 1779 int _ebuflen; 1780 void *_lib; 1781 public: 1782 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1783 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1784 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1785 void doit() { 1786 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1787 os::Linux::_stack_is_executable = true; 1788 } 1789 void* loaded_library() { return _lib; } 1790 }; 1791 1792 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) { 1793 void * result = NULL; 1794 bool load_attempted = false; 1795 1796 // Check whether the library to load might change execution rights 1797 // of the stack. If they are changed, the protection of the stack 1798 // guard pages will be lost. We need a safepoint to fix this. 1799 // 1800 // See Linux man page execstack(8) for more info. 1801 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1802 ElfFile ef(filename); 1803 if (!ef.specifies_noexecstack()) { 1804 if (!is_init_completed()) { 1805 os::Linux::_stack_is_executable = true; 1806 // This is OK - No Java threads have been created yet, and hence no 1807 // stack guard pages to fix. 1808 // 1809 // This should happen only when you are building JDK7 using a very 1810 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1811 // 1812 // Dynamic loader will make all stacks executable after 1813 // this function returns, and will not do that again. 1814 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1815 } else { 1816 warning("You have loaded library %s which might have disabled stack guard. " 1817 "The VM will try to fix the stack guard now.\n" 1818 "It's highly recommended that you fix the library with " 1819 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1820 filename); 1821 1822 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1823 JavaThread *jt = JavaThread::current(); 1824 if (jt->thread_state() != _thread_in_native) { 1825 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1826 // that requires ExecStack. Cannot enter safe point. Let's give up. 1827 warning("Unable to fix stack guard. Giving up."); 1828 } else { 1829 if (!LoadExecStackDllInVMThread) { 1830 // This is for the case where the DLL has an static 1831 // constructor function that executes JNI code. We cannot 1832 // load such DLLs in the VMThread. 1833 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1834 } 1835 1836 ThreadInVMfromNative tiv(jt); 1837 debug_only(VMNativeEntryWrapper vew;) 1838 1839 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1840 VMThread::execute(&op); 1841 if (LoadExecStackDllInVMThread) { 1842 result = op.loaded_library(); 1843 } 1844 load_attempted = true; 1845 } 1846 } 1847 } 1848 } 1849 1850 if (!load_attempted) { 1851 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1852 } 1853 1854 if (result != NULL) { 1855 // Successful loading 1856 return result; 1857 } 1858 1859 Elf32_Ehdr elf_head; 1860 int diag_msg_max_length=ebuflen-strlen(ebuf); 1861 char* diag_msg_buf=ebuf+strlen(ebuf); 1862 1863 if (diag_msg_max_length==0) { 1864 // No more space in ebuf for additional diagnostics message 1865 return NULL; 1866 } 1867 1868 1869 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1870 1871 if (file_descriptor < 0) { 1872 // Can't open library, report dlerror() message 1873 return NULL; 1874 } 1875 1876 bool failed_to_read_elf_head= 1877 (sizeof(elf_head)!= 1878 (::read(file_descriptor, &elf_head,sizeof(elf_head)))); 1879 1880 ::close(file_descriptor); 1881 if (failed_to_read_elf_head) { 1882 // file i/o error - report dlerror() msg 1883 return NULL; 1884 } 1885 1886 typedef struct { 1887 Elf32_Half code; // Actual value as defined in elf.h 1888 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1889 char elf_class; // 32 or 64 bit 1890 char endianess; // MSB or LSB 1891 char* name; // String representation 1892 } arch_t; 1893 1894 #ifndef EM_486 1895 #define EM_486 6 /* Intel 80486 */ 1896 #endif 1897 1898 static const arch_t arch_array[]={ 1899 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1900 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1901 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1902 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1903 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1904 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1905 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1906 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1907 #if defined(VM_LITTLE_ENDIAN) 1908 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"}, 1909 #else 1910 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1911 #endif 1912 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1913 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1914 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1915 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1916 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1917 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1918 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1919 }; 1920 1921 #if (defined IA32) 1922 static Elf32_Half running_arch_code=EM_386; 1923 #elif (defined AMD64) 1924 static Elf32_Half running_arch_code=EM_X86_64; 1925 #elif (defined IA64) 1926 static Elf32_Half running_arch_code=EM_IA_64; 1927 #elif (defined __sparc) && (defined _LP64) 1928 static Elf32_Half running_arch_code=EM_SPARCV9; 1929 #elif (defined __sparc) && (!defined _LP64) 1930 static Elf32_Half running_arch_code=EM_SPARC; 1931 #elif (defined __powerpc64__) 1932 static Elf32_Half running_arch_code=EM_PPC64; 1933 #elif (defined __powerpc__) 1934 static Elf32_Half running_arch_code=EM_PPC; 1935 #elif (defined ARM) 1936 static Elf32_Half running_arch_code=EM_ARM; 1937 #elif (defined S390) 1938 static Elf32_Half running_arch_code=EM_S390; 1939 #elif (defined ALPHA) 1940 static Elf32_Half running_arch_code=EM_ALPHA; 1941 #elif (defined MIPSEL) 1942 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1943 #elif (defined PARISC) 1944 static Elf32_Half running_arch_code=EM_PARISC; 1945 #elif (defined MIPS) 1946 static Elf32_Half running_arch_code=EM_MIPS; 1947 #elif (defined M68K) 1948 static Elf32_Half running_arch_code=EM_68K; 1949 #else 1950 #error Method os::dll_load requires that one of following is defined:\ 1951 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1952 #endif 1953 1954 // Identify compatability class for VM's architecture and library's architecture 1955 // Obtain string descriptions for architectures 1956 1957 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1958 int running_arch_index=-1; 1959 1960 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) { 1961 if (running_arch_code == arch_array[i].code) { 1962 running_arch_index = i; 1963 } 1964 if (lib_arch.code == arch_array[i].code) { 1965 lib_arch.compat_class = arch_array[i].compat_class; 1966 lib_arch.name = arch_array[i].name; 1967 } 1968 } 1969 1970 assert(running_arch_index != -1, 1971 "Didn't find running architecture code (running_arch_code) in arch_array"); 1972 if (running_arch_index == -1) { 1973 // Even though running architecture detection failed 1974 // we may still continue with reporting dlerror() message 1975 return NULL; 1976 } 1977 1978 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1979 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1980 return NULL; 1981 } 1982 1983 #ifndef S390 1984 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 1985 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 1986 return NULL; 1987 } 1988 #endif // !S390 1989 1990 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 1991 if (lib_arch.name!=NULL) { 1992 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1993 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 1994 lib_arch.name, arch_array[running_arch_index].name); 1995 } else { 1996 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1997 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 1998 lib_arch.code, 1999 arch_array[running_arch_index].name); 2000 } 2001 } 2002 2003 return NULL; 2004 } 2005 2006 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, 2007 int ebuflen) { 2008 void * result = ::dlopen(filename, RTLD_LAZY); 2009 if (result == NULL) { 2010 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2011 ebuf[ebuflen-1] = '\0'; 2012 } 2013 return result; 2014 } 2015 2016 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, 2017 int ebuflen) { 2018 void * result = NULL; 2019 if (LoadExecStackDllInVMThread) { 2020 result = dlopen_helper(filename, ebuf, ebuflen); 2021 } 2022 2023 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2024 // library that requires an executable stack, or which does not have this 2025 // stack attribute set, dlopen changes the stack attribute to executable. The 2026 // read protection of the guard pages gets lost. 2027 // 2028 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2029 // may have been queued at the same time. 2030 2031 if (!_stack_is_executable) { 2032 JavaThread *jt = Threads::first(); 2033 2034 while (jt) { 2035 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2036 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2037 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2038 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2039 warning("Attempt to reguard stack yellow zone failed."); 2040 } 2041 } 2042 jt = jt->next(); 2043 } 2044 } 2045 2046 return result; 2047 } 2048 2049 // glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2050 // chances are you might want to run the generated bits against glibc-2.0 2051 // libdl.so, so always use locking for any version of glibc. 2052 // 2053 void* os::dll_lookup(void* handle, const char* name) { 2054 pthread_mutex_lock(&dl_mutex); 2055 void* res = dlsym(handle, name); 2056 pthread_mutex_unlock(&dl_mutex); 2057 return res; 2058 } 2059 2060 void* os::get_default_process_handle() { 2061 return (void*)::dlopen(NULL, RTLD_LAZY); 2062 } 2063 2064 static bool _print_ascii_file(const char* filename, outputStream* st) { 2065 int fd = ::open(filename, O_RDONLY); 2066 if (fd == -1) { 2067 return false; 2068 } 2069 2070 char buf[32]; 2071 int bytes; 2072 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2073 st->print_raw(buf, bytes); 2074 } 2075 2076 ::close(fd); 2077 2078 return true; 2079 } 2080 2081 void os::print_dll_info(outputStream *st) { 2082 st->print_cr("Dynamic libraries:"); 2083 2084 char fname[32]; 2085 pid_t pid = os::Linux::gettid(); 2086 2087 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2088 2089 if (!_print_ascii_file(fname, st)) { 2090 st->print("Can not get library information for pid = %d\n", pid); 2091 } 2092 } 2093 2094 int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) { 2095 FILE *procmapsFile = NULL; 2096 2097 // Open the procfs maps file for the current process 2098 if ((procmapsFile = fopen("/proc/self/maps", "r")) != NULL) { 2099 // Allocate PATH_MAX for file name plus a reasonable size for other fields. 2100 char line[PATH_MAX + 100]; 2101 2102 // Read line by line from 'file' 2103 while (fgets(line, sizeof(line), procmapsFile) != NULL) { 2104 u8 base, top, offset, inode; 2105 char permissions[5]; 2106 char device[6]; 2107 char name[PATH_MAX + 1]; 2108 2109 // Parse fields from line 2110 sscanf(line, "%lx-%lx %4s %lx %5s %ld %s", &base, &top, permissions, &offset, device, &inode, name); 2111 2112 // Filter by device id '00:00' so that we only get file system mapped files. 2113 if (strcmp(device, "00:00") != 0) { 2114 2115 // Call callback with the fields of interest 2116 if(callback(name, (address)base, (address)top, param)) { 2117 // Oops abort, callback aborted 2118 fclose(procmapsFile); 2119 return 1; 2120 } 2121 } 2122 } 2123 fclose(procmapsFile); 2124 } 2125 return 0; 2126 } 2127 2128 void os::print_os_info_brief(outputStream* st) { 2129 os::Linux::print_distro_info(st); 2130 2131 os::Posix::print_uname_info(st); 2132 2133 os::Linux::print_libversion_info(st); 2134 2135 } 2136 2137 void os::print_os_info(outputStream* st) { 2138 st->print("OS:"); 2139 2140 os::Linux::print_distro_info(st); 2141 2142 os::Posix::print_uname_info(st); 2143 2144 // Print warning if unsafe chroot environment detected 2145 if (unsafe_chroot_detected) { 2146 st->print("WARNING!! "); 2147 st->print_cr("%s", unstable_chroot_error); 2148 } 2149 2150 os::Linux::print_libversion_info(st); 2151 2152 os::Posix::print_rlimit_info(st); 2153 2154 os::Posix::print_load_average(st); 2155 2156 os::Linux::print_full_memory_info(st); 2157 } 2158 2159 // Try to identify popular distros. 2160 // Most Linux distributions have a /etc/XXX-release file, which contains 2161 // the OS version string. Newer Linux distributions have a /etc/lsb-release 2162 // file that also contains the OS version string. Some have more than one 2163 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2164 // /etc/redhat-release.), so the order is important. 2165 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2166 // their own specific XXX-release file as well as a redhat-release file. 2167 // Because of this the XXX-release file needs to be searched for before the 2168 // redhat-release file. 2169 // Since Red Hat has a lsb-release file that is not very descriptive the 2170 // search for redhat-release needs to be before lsb-release. 2171 // Since the lsb-release file is the new standard it needs to be searched 2172 // before the older style release files. 2173 // Searching system-release (Red Hat) and os-release (other Linuxes) are a 2174 // next to last resort. The os-release file is a new standard that contains 2175 // distribution information and the system-release file seems to be an old 2176 // standard that has been replaced by the lsb-release and os-release files. 2177 // Searching for the debian_version file is the last resort. It contains 2178 // an informative string like "6.0.6" or "wheezy/sid". Because of this 2179 // "Debian " is printed before the contents of the debian_version file. 2180 void os::Linux::print_distro_info(outputStream* st) { 2181 if (!_print_ascii_file("/etc/oracle-release", st) && 2182 !_print_ascii_file("/etc/mandriva-release", st) && 2183 !_print_ascii_file("/etc/mandrake-release", st) && 2184 !_print_ascii_file("/etc/sun-release", st) && 2185 !_print_ascii_file("/etc/redhat-release", st) && 2186 !_print_ascii_file("/etc/lsb-release", st) && 2187 !_print_ascii_file("/etc/SuSE-release", st) && 2188 !_print_ascii_file("/etc/turbolinux-release", st) && 2189 !_print_ascii_file("/etc/gentoo-release", st) && 2190 !_print_ascii_file("/etc/ltib-release", st) && 2191 !_print_ascii_file("/etc/angstrom-version", st) && 2192 !_print_ascii_file("/etc/system-release", st) && 2193 !_print_ascii_file("/etc/os-release", st)) { 2194 2195 if (file_exists("/etc/debian_version")) { 2196 st->print("Debian "); 2197 _print_ascii_file("/etc/debian_version", st); 2198 } else { 2199 st->print("Linux"); 2200 } 2201 } 2202 st->cr(); 2203 } 2204 2205 void os::Linux::print_libversion_info(outputStream* st) { 2206 // libc, pthread 2207 st->print("libc:"); 2208 st->print("%s ", os::Linux::glibc_version()); 2209 st->print("%s ", os::Linux::libpthread_version()); 2210 if (os::Linux::is_LinuxThreads()) { 2211 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2212 } 2213 st->cr(); 2214 } 2215 2216 void os::Linux::print_full_memory_info(outputStream* st) { 2217 st->print("\n/proc/meminfo:\n"); 2218 _print_ascii_file("/proc/meminfo", st); 2219 st->cr(); 2220 } 2221 2222 void os::print_memory_info(outputStream* st) { 2223 2224 st->print("Memory:"); 2225 st->print(" %dk page", os::vm_page_size()>>10); 2226 2227 // values in struct sysinfo are "unsigned long" 2228 struct sysinfo si; 2229 sysinfo(&si); 2230 2231 st->print(", physical " UINT64_FORMAT "k", 2232 os::physical_memory() >> 10); 2233 st->print("(" UINT64_FORMAT "k free)", 2234 os::available_memory() >> 10); 2235 st->print(", swap " UINT64_FORMAT "k", 2236 ((jlong)si.totalswap * si.mem_unit) >> 10); 2237 st->print("(" UINT64_FORMAT "k free)", 2238 ((jlong)si.freeswap * si.mem_unit) >> 10); 2239 st->cr(); 2240 } 2241 2242 void os::pd_print_cpu_info(outputStream* st) { 2243 st->print("\n/proc/cpuinfo:\n"); 2244 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2245 st->print(" <Not Available>"); 2246 } 2247 st->cr(); 2248 } 2249 2250 void os::print_siginfo(outputStream* st, void* siginfo) { 2251 const siginfo_t* si = (const siginfo_t*)siginfo; 2252 2253 os::Posix::print_siginfo_brief(st, si); 2254 #if INCLUDE_CDS 2255 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2256 UseSharedSpaces) { 2257 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2258 if (mapinfo->is_in_shared_space(si->si_addr)) { 2259 st->print("\n\nError accessing class data sharing archive." \ 2260 " Mapped file inaccessible during execution, " \ 2261 " possible disk/network problem."); 2262 } 2263 } 2264 #endif 2265 st->cr(); 2266 } 2267 2268 2269 static void print_signal_handler(outputStream* st, int sig, 2270 char* buf, size_t buflen); 2271 2272 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2273 st->print_cr("Signal Handlers:"); 2274 print_signal_handler(st, SIGSEGV, buf, buflen); 2275 print_signal_handler(st, SIGBUS , buf, buflen); 2276 print_signal_handler(st, SIGFPE , buf, buflen); 2277 print_signal_handler(st, SIGPIPE, buf, buflen); 2278 print_signal_handler(st, SIGXFSZ, buf, buflen); 2279 print_signal_handler(st, SIGILL , buf, buflen); 2280 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2281 print_signal_handler(st, SR_signum, buf, buflen); 2282 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2283 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2284 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2285 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2286 #if defined(PPC64) 2287 print_signal_handler(st, SIGTRAP, buf, buflen); 2288 #endif 2289 } 2290 2291 static char saved_jvm_path[MAXPATHLEN] = {0}; 2292 2293 // Find the full path to the current module, libjvm.so 2294 void os::jvm_path(char *buf, jint buflen) { 2295 // Error checking. 2296 if (buflen < MAXPATHLEN) { 2297 assert(false, "must use a large-enough buffer"); 2298 buf[0] = '\0'; 2299 return; 2300 } 2301 // Lazy resolve the path to current module. 2302 if (saved_jvm_path[0] != 0) { 2303 strcpy(buf, saved_jvm_path); 2304 return; 2305 } 2306 2307 char dli_fname[MAXPATHLEN]; 2308 bool ret = dll_address_to_library_name( 2309 CAST_FROM_FN_PTR(address, os::jvm_path), 2310 dli_fname, sizeof(dli_fname), NULL); 2311 assert(ret, "cannot locate libjvm"); 2312 char *rp = NULL; 2313 if (ret && dli_fname[0] != '\0') { 2314 rp = realpath(dli_fname, buf); 2315 } 2316 if (rp == NULL) { 2317 return; 2318 } 2319 2320 if (Arguments::sun_java_launcher_is_altjvm()) { 2321 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical 2322 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". 2323 // If "/jre/lib/" appears at the right place in the string, then 2324 // assume we are installed in a JDK and we're done. Otherwise, check 2325 // for a JAVA_HOME environment variable and fix up the path so it 2326 // looks like libjvm.so is installed there (append a fake suffix 2327 // hotspot/libjvm.so). 2328 const char *p = buf + strlen(buf) - 1; 2329 for (int count = 0; p > buf && count < 5; ++count) { 2330 for (--p; p > buf && *p != '/'; --p) 2331 /* empty */ ; 2332 } 2333 2334 if (strncmp(p, "/jre/lib/", 9) != 0) { 2335 // Look for JAVA_HOME in the environment. 2336 char* java_home_var = ::getenv("JAVA_HOME"); 2337 if (java_home_var != NULL && java_home_var[0] != 0) { 2338 char* jrelib_p; 2339 int len; 2340 2341 // Check the current module name "libjvm.so". 2342 p = strrchr(buf, '/'); 2343 if (p == NULL) { 2344 return; 2345 } 2346 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2347 2348 rp = realpath(java_home_var, buf); 2349 if (rp == NULL) { 2350 return; 2351 } 2352 2353 // determine if this is a legacy image or modules image 2354 // modules image doesn't have "jre" subdirectory 2355 len = strlen(buf); 2356 assert(len < buflen, "Ran out of buffer room"); 2357 jrelib_p = buf + len; 2358 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2359 if (0 != access(buf, F_OK)) { 2360 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2361 } 2362 2363 if (0 == access(buf, F_OK)) { 2364 // Use current module name "libjvm.so" 2365 len = strlen(buf); 2366 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2367 } else { 2368 // Go back to path of .so 2369 rp = realpath(dli_fname, buf); 2370 if (rp == NULL) { 2371 return; 2372 } 2373 } 2374 } 2375 } 2376 } 2377 2378 strncpy(saved_jvm_path, buf, MAXPATHLEN); 2379 saved_jvm_path[MAXPATHLEN - 1] = '\0'; 2380 } 2381 2382 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2383 // no prefix required, not even "_" 2384 } 2385 2386 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2387 // no suffix required 2388 } 2389 2390 //////////////////////////////////////////////////////////////////////////////// 2391 // sun.misc.Signal support 2392 2393 static volatile jint sigint_count = 0; 2394 2395 static void UserHandler(int sig, void *siginfo, void *context) { 2396 // 4511530 - sem_post is serialized and handled by the manager thread. When 2397 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2398 // don't want to flood the manager thread with sem_post requests. 2399 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) { 2400 return; 2401 } 2402 2403 // Ctrl-C is pressed during error reporting, likely because the error 2404 // handler fails to abort. Let VM die immediately. 2405 if (sig == SIGINT && is_error_reported()) { 2406 os::die(); 2407 } 2408 2409 os::signal_notify(sig); 2410 } 2411 2412 void* os::user_handler() { 2413 return CAST_FROM_FN_PTR(void*, UserHandler); 2414 } 2415 2416 class Semaphore : public StackObj { 2417 public: 2418 Semaphore(); 2419 ~Semaphore(); 2420 void signal(); 2421 void wait(); 2422 bool trywait(); 2423 bool timedwait(unsigned int sec, int nsec); 2424 private: 2425 sem_t _semaphore; 2426 }; 2427 2428 Semaphore::Semaphore() { 2429 sem_init(&_semaphore, 0, 0); 2430 } 2431 2432 Semaphore::~Semaphore() { 2433 sem_destroy(&_semaphore); 2434 } 2435 2436 void Semaphore::signal() { 2437 sem_post(&_semaphore); 2438 } 2439 2440 void Semaphore::wait() { 2441 sem_wait(&_semaphore); 2442 } 2443 2444 bool Semaphore::trywait() { 2445 return sem_trywait(&_semaphore) == 0; 2446 } 2447 2448 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2449 2450 struct timespec ts; 2451 // Semaphore's are always associated with CLOCK_REALTIME 2452 os::Linux::clock_gettime(CLOCK_REALTIME, &ts); 2453 // see unpackTime for discussion on overflow checking 2454 if (sec >= MAX_SECS) { 2455 ts.tv_sec += MAX_SECS; 2456 ts.tv_nsec = 0; 2457 } else { 2458 ts.tv_sec += sec; 2459 ts.tv_nsec += nsec; 2460 if (ts.tv_nsec >= NANOSECS_PER_SEC) { 2461 ts.tv_nsec -= NANOSECS_PER_SEC; 2462 ++ts.tv_sec; // note: this must be <= max_secs 2463 } 2464 } 2465 2466 while (1) { 2467 int result = sem_timedwait(&_semaphore, &ts); 2468 if (result == 0) { 2469 return true; 2470 } else if (errno == EINTR) { 2471 continue; 2472 } else if (errno == ETIMEDOUT) { 2473 return false; 2474 } else { 2475 return false; 2476 } 2477 } 2478 } 2479 2480 extern "C" { 2481 typedef void (*sa_handler_t)(int); 2482 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2483 } 2484 2485 void* os::signal(int signal_number, void* handler) { 2486 struct sigaction sigAct, oldSigAct; 2487 2488 sigfillset(&(sigAct.sa_mask)); 2489 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2490 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2491 2492 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2493 // -1 means registration failed 2494 return (void *)-1; 2495 } 2496 2497 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2498 } 2499 2500 void os::signal_raise(int signal_number) { 2501 ::raise(signal_number); 2502 } 2503 2504 // The following code is moved from os.cpp for making this 2505 // code platform specific, which it is by its very nature. 2506 2507 // Will be modified when max signal is changed to be dynamic 2508 int os::sigexitnum_pd() { 2509 return NSIG; 2510 } 2511 2512 // a counter for each possible signal value 2513 static volatile jint pending_signals[NSIG+1] = { 0 }; 2514 2515 // Linux(POSIX) specific hand shaking semaphore. 2516 static sem_t sig_sem; 2517 static Semaphore sr_semaphore; 2518 2519 void os::signal_init_pd() { 2520 // Initialize signal structures 2521 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2522 2523 // Initialize signal semaphore 2524 ::sem_init(&sig_sem, 0, 0); 2525 } 2526 2527 void os::signal_notify(int sig) { 2528 Atomic::inc(&pending_signals[sig]); 2529 ::sem_post(&sig_sem); 2530 } 2531 2532 static int check_pending_signals(bool wait) { 2533 Atomic::store(0, &sigint_count); 2534 for (;;) { 2535 for (int i = 0; i < NSIG + 1; i++) { 2536 jint n = pending_signals[i]; 2537 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2538 return i; 2539 } 2540 } 2541 if (!wait) { 2542 return -1; 2543 } 2544 JavaThread *thread = JavaThread::current(); 2545 ThreadBlockInVM tbivm(thread); 2546 2547 bool threadIsSuspended; 2548 do { 2549 thread->set_suspend_equivalent(); 2550 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2551 ::sem_wait(&sig_sem); 2552 2553 // were we externally suspended while we were waiting? 2554 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2555 if (threadIsSuspended) { 2556 // The semaphore has been incremented, but while we were waiting 2557 // another thread suspended us. We don't want to continue running 2558 // while suspended because that would surprise the thread that 2559 // suspended us. 2560 ::sem_post(&sig_sem); 2561 2562 thread->java_suspend_self(); 2563 } 2564 } while (threadIsSuspended); 2565 } 2566 } 2567 2568 int os::signal_lookup() { 2569 return check_pending_signals(false); 2570 } 2571 2572 int os::signal_wait() { 2573 return check_pending_signals(true); 2574 } 2575 2576 //////////////////////////////////////////////////////////////////////////////// 2577 // Virtual Memory 2578 2579 int os::vm_page_size() { 2580 // Seems redundant as all get out 2581 assert(os::Linux::page_size() != -1, "must call os::init"); 2582 return os::Linux::page_size(); 2583 } 2584 2585 // Solaris allocates memory by pages. 2586 int os::vm_allocation_granularity() { 2587 assert(os::Linux::page_size() != -1, "must call os::init"); 2588 return os::Linux::page_size(); 2589 } 2590 2591 // Rationale behind this function: 2592 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2593 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2594 // samples for JITted code. Here we create private executable mapping over the code cache 2595 // and then we can use standard (well, almost, as mapping can change) way to provide 2596 // info for the reporting script by storing timestamp and location of symbol 2597 void linux_wrap_code(char* base, size_t size) { 2598 static volatile jint cnt = 0; 2599 2600 if (!UseOprofile) { 2601 return; 2602 } 2603 2604 char buf[PATH_MAX+1]; 2605 int num = Atomic::add(1, &cnt); 2606 2607 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2608 os::get_temp_directory(), os::current_process_id(), num); 2609 unlink(buf); 2610 2611 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2612 2613 if (fd != -1) { 2614 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2615 if (rv != (off_t)-1) { 2616 if (::write(fd, "", 1) == 1) { 2617 mmap(base, size, 2618 PROT_READ|PROT_WRITE|PROT_EXEC, 2619 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2620 } 2621 } 2622 ::close(fd); 2623 unlink(buf); 2624 } 2625 } 2626 2627 static bool recoverable_mmap_error(int err) { 2628 // See if the error is one we can let the caller handle. This 2629 // list of errno values comes from JBS-6843484. I can't find a 2630 // Linux man page that documents this specific set of errno 2631 // values so while this list currently matches Solaris, it may 2632 // change as we gain experience with this failure mode. 2633 switch (err) { 2634 case EBADF: 2635 case EINVAL: 2636 case ENOTSUP: 2637 // let the caller deal with these errors 2638 return true; 2639 2640 default: 2641 // Any remaining errors on this OS can cause our reserved mapping 2642 // to be lost. That can cause confusion where different data 2643 // structures think they have the same memory mapped. The worst 2644 // scenario is if both the VM and a library think they have the 2645 // same memory mapped. 2646 return false; 2647 } 2648 } 2649 2650 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2651 int err) { 2652 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2653 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2654 strerror(err), err); 2655 } 2656 2657 static void warn_fail_commit_memory(char* addr, size_t size, 2658 size_t alignment_hint, bool exec, 2659 int err) { 2660 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2661 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2662 alignment_hint, exec, strerror(err), err); 2663 } 2664 2665 // NOTE: Linux kernel does not really reserve the pages for us. 2666 // All it does is to check if there are enough free pages 2667 // left at the time of mmap(). This could be a potential 2668 // problem. 2669 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2670 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2671 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2672 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2673 if (res != (uintptr_t) MAP_FAILED) { 2674 if (UseNUMAInterleaving) { 2675 numa_make_global(addr, size); 2676 } 2677 return 0; 2678 } 2679 2680 int err = errno; // save errno from mmap() call above 2681 2682 if (!recoverable_mmap_error(err)) { 2683 warn_fail_commit_memory(addr, size, exec, err); 2684 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2685 } 2686 2687 return err; 2688 } 2689 2690 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2691 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2692 } 2693 2694 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2695 const char* mesg) { 2696 assert(mesg != NULL, "mesg must be specified"); 2697 int err = os::Linux::commit_memory_impl(addr, size, exec); 2698 if (err != 0) { 2699 // the caller wants all commit errors to exit with the specified mesg: 2700 warn_fail_commit_memory(addr, size, exec, err); 2701 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2702 } 2703 } 2704 2705 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2706 #ifndef MAP_HUGETLB 2707 #define MAP_HUGETLB 0x40000 2708 #endif 2709 2710 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2711 #ifndef MADV_HUGEPAGE 2712 #define MADV_HUGEPAGE 14 2713 #endif 2714 2715 int os::Linux::commit_memory_impl(char* addr, size_t size, 2716 size_t alignment_hint, bool exec) { 2717 int err = os::Linux::commit_memory_impl(addr, size, exec); 2718 if (err == 0) { 2719 realign_memory(addr, size, alignment_hint); 2720 } 2721 return err; 2722 } 2723 2724 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2725 bool exec) { 2726 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2727 } 2728 2729 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2730 size_t alignment_hint, bool exec, 2731 const char* mesg) { 2732 assert(mesg != NULL, "mesg must be specified"); 2733 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2734 if (err != 0) { 2735 // the caller wants all commit errors to exit with the specified mesg: 2736 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2737 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2738 } 2739 } 2740 2741 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2742 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2743 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2744 // be supported or the memory may already be backed by huge pages. 2745 ::madvise(addr, bytes, MADV_HUGEPAGE); 2746 } 2747 } 2748 2749 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2750 // This method works by doing an mmap over an existing mmaping and effectively discarding 2751 // the existing pages. However it won't work for SHM-based large pages that cannot be 2752 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2753 // small pages on top of the SHM segment. This method always works for small pages, so we 2754 // allow that in any case. 2755 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2756 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2757 } 2758 } 2759 2760 void os::numa_make_global(char *addr, size_t bytes) { 2761 Linux::numa_interleave_memory(addr, bytes); 2762 } 2763 2764 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2765 // bind policy to MPOL_PREFERRED for the current thread. 2766 #define USE_MPOL_PREFERRED 0 2767 2768 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2769 // To make NUMA and large pages more robust when both enabled, we need to ease 2770 // the requirements on where the memory should be allocated. MPOL_BIND is the 2771 // default policy and it will force memory to be allocated on the specified 2772 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2773 // the specified node, but will not force it. Using this policy will prevent 2774 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2775 // free large pages. 2776 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2777 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2778 } 2779 2780 bool os::numa_topology_changed() { return false; } 2781 2782 size_t os::numa_get_groups_num() { 2783 int max_node = Linux::numa_max_node(); 2784 return max_node > 0 ? max_node + 1 : 1; 2785 } 2786 2787 int os::numa_get_group_id() { 2788 int cpu_id = Linux::sched_getcpu(); 2789 if (cpu_id != -1) { 2790 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2791 if (lgrp_id != -1) { 2792 return lgrp_id; 2793 } 2794 } 2795 return 0; 2796 } 2797 2798 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2799 for (size_t i = 0; i < size; i++) { 2800 ids[i] = i; 2801 } 2802 return size; 2803 } 2804 2805 bool os::get_page_info(char *start, page_info* info) { 2806 return false; 2807 } 2808 2809 char *os::scan_pages(char *start, char* end, page_info* page_expected, 2810 page_info* page_found) { 2811 return end; 2812 } 2813 2814 2815 int os::Linux::sched_getcpu_syscall(void) { 2816 unsigned int cpu; 2817 int retval = -1; 2818 2819 #if defined(IA32) 2820 #ifndef SYS_getcpu 2821 #define SYS_getcpu 318 2822 #endif 2823 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2824 #elif defined(AMD64) 2825 // Unfortunately we have to bring all these macros here from vsyscall.h 2826 // to be able to compile on old linuxes. 2827 #define __NR_vgetcpu 2 2828 #define VSYSCALL_START (-10UL << 20) 2829 #define VSYSCALL_SIZE 1024 2830 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2831 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2832 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2833 retval = vgetcpu(&cpu, NULL, NULL); 2834 #endif 2835 2836 return (retval == -1) ? retval : cpu; 2837 } 2838 2839 // Something to do with the numa-aware allocator needs these symbols 2840 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2841 extern "C" JNIEXPORT void numa_error(char *where) { } 2842 extern "C" JNIEXPORT int fork1() { return fork(); } 2843 2844 2845 // If we are running with libnuma version > 2, then we should 2846 // be trying to use symbols with versions 1.1 2847 // If we are running with earlier version, which did not have symbol versions, 2848 // we should use the base version. 2849 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2850 void *f = dlvsym(handle, name, "libnuma_1.1"); 2851 if (f == NULL) { 2852 f = dlsym(handle, name); 2853 } 2854 return f; 2855 } 2856 2857 bool os::Linux::libnuma_init() { 2858 // sched_getcpu() should be in libc. 2859 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2860 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2861 2862 // If it's not, try a direct syscall. 2863 if (sched_getcpu() == -1) { 2864 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2865 (void*)&sched_getcpu_syscall)); 2866 } 2867 2868 if (sched_getcpu() != -1) { // Does it work? 2869 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2870 if (handle != NULL) { 2871 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2872 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2873 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2874 libnuma_dlsym(handle, "numa_max_node"))); 2875 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2876 libnuma_dlsym(handle, "numa_available"))); 2877 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2878 libnuma_dlsym(handle, "numa_tonode_memory"))); 2879 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2880 libnuma_dlsym(handle, "numa_interleave_memory"))); 2881 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2882 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2883 2884 2885 if (numa_available() != -1) { 2886 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2887 // Create a cpu -> node mapping 2888 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2889 rebuild_cpu_to_node_map(); 2890 return true; 2891 } 2892 } 2893 } 2894 return false; 2895 } 2896 2897 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2898 // The table is later used in get_node_by_cpu(). 2899 void os::Linux::rebuild_cpu_to_node_map() { 2900 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2901 // in libnuma (possible values are starting from 16, 2902 // and continuing up with every other power of 2, but less 2903 // than the maximum number of CPUs supported by kernel), and 2904 // is a subject to change (in libnuma version 2 the requirements 2905 // are more reasonable) we'll just hardcode the number they use 2906 // in the library. 2907 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2908 2909 size_t cpu_num = os::active_processor_count(); 2910 size_t cpu_map_size = NCPUS / BitsPerCLong; 2911 size_t cpu_map_valid_size = 2912 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2913 2914 cpu_to_node()->clear(); 2915 cpu_to_node()->at_grow(cpu_num - 1); 2916 size_t node_num = numa_get_groups_num(); 2917 2918 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2919 for (size_t i = 0; i < node_num; i++) { 2920 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2921 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2922 if (cpu_map[j] != 0) { 2923 for (size_t k = 0; k < BitsPerCLong; k++) { 2924 if (cpu_map[j] & (1UL << k)) { 2925 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2926 } 2927 } 2928 } 2929 } 2930 } 2931 } 2932 FREE_C_HEAP_ARRAY(unsigned long, cpu_map); 2933 } 2934 2935 int os::Linux::get_node_by_cpu(int cpu_id) { 2936 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2937 return cpu_to_node()->at(cpu_id); 2938 } 2939 return -1; 2940 } 2941 2942 GrowableArray<int>* os::Linux::_cpu_to_node; 2943 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2944 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2945 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2946 os::Linux::numa_available_func_t os::Linux::_numa_available; 2947 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2948 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2949 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2950 unsigned long* os::Linux::_numa_all_nodes; 2951 2952 bool os::pd_uncommit_memory(char* addr, size_t size) { 2953 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2954 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2955 return res != (uintptr_t) MAP_FAILED; 2956 } 2957 2958 static address get_stack_commited_bottom(address bottom, size_t size) { 2959 address nbot = bottom; 2960 address ntop = bottom + size; 2961 2962 size_t page_sz = os::vm_page_size(); 2963 unsigned pages = size / page_sz; 2964 2965 unsigned char vec[1]; 2966 unsigned imin = 1, imax = pages + 1, imid; 2967 int mincore_return_value = 0; 2968 2969 assert(imin <= imax, "Unexpected page size"); 2970 2971 while (imin < imax) { 2972 imid = (imax + imin) / 2; 2973 nbot = ntop - (imid * page_sz); 2974 2975 // Use a trick with mincore to check whether the page is mapped or not. 2976 // mincore sets vec to 1 if page resides in memory and to 0 if page 2977 // is swapped output but if page we are asking for is unmapped 2978 // it returns -1,ENOMEM 2979 mincore_return_value = mincore(nbot, page_sz, vec); 2980 2981 if (mincore_return_value == -1) { 2982 // Page is not mapped go up 2983 // to find first mapped page 2984 if (errno != EAGAIN) { 2985 assert(errno == ENOMEM, "Unexpected mincore errno"); 2986 imax = imid; 2987 } 2988 } else { 2989 // Page is mapped go down 2990 // to find first not mapped page 2991 imin = imid + 1; 2992 } 2993 } 2994 2995 nbot = nbot + page_sz; 2996 2997 // Adjust stack bottom one page up if last checked page is not mapped 2998 if (mincore_return_value == -1) { 2999 nbot = nbot + page_sz; 3000 } 3001 3002 return nbot; 3003 } 3004 3005 3006 // Linux uses a growable mapping for the stack, and if the mapping for 3007 // the stack guard pages is not removed when we detach a thread the 3008 // stack cannot grow beyond the pages where the stack guard was 3009 // mapped. If at some point later in the process the stack expands to 3010 // that point, the Linux kernel cannot expand the stack any further 3011 // because the guard pages are in the way, and a segfault occurs. 3012 // 3013 // However, it's essential not to split the stack region by unmapping 3014 // a region (leaving a hole) that's already part of the stack mapping, 3015 // so if the stack mapping has already grown beyond the guard pages at 3016 // the time we create them, we have to truncate the stack mapping. 3017 // So, we need to know the extent of the stack mapping when 3018 // create_stack_guard_pages() is called. 3019 3020 // We only need this for stacks that are growable: at the time of 3021 // writing thread stacks don't use growable mappings (i.e. those 3022 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 3023 // only applies to the main thread. 3024 3025 // If the (growable) stack mapping already extends beyond the point 3026 // where we're going to put our guard pages, truncate the mapping at 3027 // that point by munmap()ping it. This ensures that when we later 3028 // munmap() the guard pages we don't leave a hole in the stack 3029 // mapping. This only affects the main/initial thread 3030 3031 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3032 if (os::Linux::is_initial_thread()) { 3033 // As we manually grow stack up to bottom inside create_attached_thread(), 3034 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3035 // we don't need to do anything special. 3036 // Check it first, before calling heavy function. 3037 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3038 unsigned char vec[1]; 3039 3040 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3041 // Fallback to slow path on all errors, including EAGAIN 3042 stack_extent = (uintptr_t) get_stack_commited_bottom( 3043 os::Linux::initial_thread_stack_bottom(), 3044 (size_t)addr - stack_extent); 3045 } 3046 3047 if (stack_extent < (uintptr_t)addr) { 3048 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3049 } 3050 } 3051 3052 return os::commit_memory(addr, size, !ExecMem); 3053 } 3054 3055 // If this is a growable mapping, remove the guard pages entirely by 3056 // munmap()ping them. If not, just call uncommit_memory(). This only 3057 // affects the main/initial thread, but guard against future OS changes 3058 // It's safe to always unmap guard pages for initial thread because we 3059 // always place it right after end of the mapped region 3060 3061 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3062 uintptr_t stack_extent, stack_base; 3063 3064 if (os::Linux::is_initial_thread()) { 3065 return ::munmap(addr, size) == 0; 3066 } 3067 3068 return os::uncommit_memory(addr, size); 3069 } 3070 3071 static address _highest_vm_reserved_address = NULL; 3072 3073 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3074 // at 'requested_addr'. If there are existing memory mappings at the same 3075 // location, however, they will be overwritten. If 'fixed' is false, 3076 // 'requested_addr' is only treated as a hint, the return value may or 3077 // may not start from the requested address. Unlike Linux mmap(), this 3078 // function returns NULL to indicate failure. 3079 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3080 char * addr; 3081 int flags; 3082 3083 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3084 if (fixed) { 3085 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3086 flags |= MAP_FIXED; 3087 } 3088 3089 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3090 // touch an uncommitted page. Otherwise, the read/write might 3091 // succeed if we have enough swap space to back the physical page. 3092 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3093 flags, -1, 0); 3094 3095 if (addr != MAP_FAILED) { 3096 // anon_mmap() should only get called during VM initialization, 3097 // don't need lock (actually we can skip locking even it can be called 3098 // from multiple threads, because _highest_vm_reserved_address is just a 3099 // hint about the upper limit of non-stack memory regions.) 3100 if ((address)addr + bytes > _highest_vm_reserved_address) { 3101 _highest_vm_reserved_address = (address)addr + bytes; 3102 } 3103 } 3104 3105 return addr == MAP_FAILED ? NULL : addr; 3106 } 3107 3108 // Don't update _highest_vm_reserved_address, because there might be memory 3109 // regions above addr + size. If so, releasing a memory region only creates 3110 // a hole in the address space, it doesn't help prevent heap-stack collision. 3111 // 3112 static int anon_munmap(char * addr, size_t size) { 3113 return ::munmap(addr, size) == 0; 3114 } 3115 3116 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3117 size_t alignment_hint) { 3118 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3119 } 3120 3121 bool os::pd_release_memory(char* addr, size_t size) { 3122 return anon_munmap(addr, size); 3123 } 3124 3125 static address highest_vm_reserved_address() { 3126 return _highest_vm_reserved_address; 3127 } 3128 3129 static bool linux_mprotect(char* addr, size_t size, int prot) { 3130 // Linux wants the mprotect address argument to be page aligned. 3131 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3132 3133 // According to SUSv3, mprotect() should only be used with mappings 3134 // established by mmap(), and mmap() always maps whole pages. Unaligned 3135 // 'addr' likely indicates problem in the VM (e.g. trying to change 3136 // protection of malloc'ed or statically allocated memory). Check the 3137 // caller if you hit this assert. 3138 assert(addr == bottom, "sanity check"); 3139 3140 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3141 return ::mprotect(bottom, size, prot) == 0; 3142 } 3143 3144 // Set protections specified 3145 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3146 bool is_committed) { 3147 unsigned int p = 0; 3148 switch (prot) { 3149 case MEM_PROT_NONE: p = PROT_NONE; break; 3150 case MEM_PROT_READ: p = PROT_READ; break; 3151 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3152 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3153 default: 3154 ShouldNotReachHere(); 3155 } 3156 // is_committed is unused. 3157 return linux_mprotect(addr, bytes, p); 3158 } 3159 3160 bool os::guard_memory(char* addr, size_t size) { 3161 return linux_mprotect(addr, size, PROT_NONE); 3162 } 3163 3164 bool os::unguard_memory(char* addr, size_t size) { 3165 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3166 } 3167 3168 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, 3169 size_t page_size) { 3170 bool result = false; 3171 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3172 MAP_ANONYMOUS|MAP_PRIVATE, 3173 -1, 0); 3174 if (p != MAP_FAILED) { 3175 void *aligned_p = align_ptr_up(p, page_size); 3176 3177 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3178 3179 munmap(p, page_size * 2); 3180 } 3181 3182 if (warn && !result) { 3183 warning("TransparentHugePages is not supported by the operating system."); 3184 } 3185 3186 return result; 3187 } 3188 3189 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3190 bool result = false; 3191 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3192 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3193 -1, 0); 3194 3195 if (p != MAP_FAILED) { 3196 // We don't know if this really is a huge page or not. 3197 FILE *fp = fopen("/proc/self/maps", "r"); 3198 if (fp) { 3199 while (!feof(fp)) { 3200 char chars[257]; 3201 long x = 0; 3202 if (fgets(chars, sizeof(chars), fp)) { 3203 if (sscanf(chars, "%lx-%*x", &x) == 1 3204 && x == (long)p) { 3205 if (strstr (chars, "hugepage")) { 3206 result = true; 3207 break; 3208 } 3209 } 3210 } 3211 } 3212 fclose(fp); 3213 } 3214 munmap(p, page_size); 3215 } 3216 3217 if (warn && !result) { 3218 warning("HugeTLBFS is not supported by the operating system."); 3219 } 3220 3221 return result; 3222 } 3223 3224 // Set the coredump_filter bits to include largepages in core dump (bit 6) 3225 // 3226 // From the coredump_filter documentation: 3227 // 3228 // - (bit 0) anonymous private memory 3229 // - (bit 1) anonymous shared memory 3230 // - (bit 2) file-backed private memory 3231 // - (bit 3) file-backed shared memory 3232 // - (bit 4) ELF header pages in file-backed private memory areas (it is 3233 // effective only if the bit 2 is cleared) 3234 // - (bit 5) hugetlb private memory 3235 // - (bit 6) hugetlb shared memory 3236 // 3237 static void set_coredump_filter(void) { 3238 FILE *f; 3239 long cdm; 3240 3241 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3242 return; 3243 } 3244 3245 if (fscanf(f, "%lx", &cdm) != 1) { 3246 fclose(f); 3247 return; 3248 } 3249 3250 rewind(f); 3251 3252 if ((cdm & LARGEPAGES_BIT) == 0) { 3253 cdm |= LARGEPAGES_BIT; 3254 fprintf(f, "%#lx", cdm); 3255 } 3256 3257 fclose(f); 3258 } 3259 3260 // Large page support 3261 3262 static size_t _large_page_size = 0; 3263 3264 size_t os::Linux::find_large_page_size() { 3265 size_t large_page_size = 0; 3266 3267 // large_page_size on Linux is used to round up heap size. x86 uses either 3268 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3269 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3270 // page as large as 256M. 3271 // 3272 // Here we try to figure out page size by parsing /proc/meminfo and looking 3273 // for a line with the following format: 3274 // Hugepagesize: 2048 kB 3275 // 3276 // If we can't determine the value (e.g. /proc is not mounted, or the text 3277 // format has been changed), we'll use the largest page size supported by 3278 // the processor. 3279 3280 #ifndef ZERO 3281 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3282 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3283 #endif // ZERO 3284 3285 FILE *fp = fopen("/proc/meminfo", "r"); 3286 if (fp) { 3287 while (!feof(fp)) { 3288 int x = 0; 3289 char buf[16]; 3290 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3291 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3292 large_page_size = x * K; 3293 break; 3294 } 3295 } else { 3296 // skip to next line 3297 for (;;) { 3298 int ch = fgetc(fp); 3299 if (ch == EOF || ch == (int)'\n') break; 3300 } 3301 } 3302 } 3303 fclose(fp); 3304 } 3305 3306 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3307 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3308 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3309 proper_unit_for_byte_size(large_page_size)); 3310 } 3311 3312 return large_page_size; 3313 } 3314 3315 size_t os::Linux::setup_large_page_size() { 3316 _large_page_size = Linux::find_large_page_size(); 3317 const size_t default_page_size = (size_t)Linux::page_size(); 3318 if (_large_page_size > default_page_size) { 3319 _page_sizes[0] = _large_page_size; 3320 _page_sizes[1] = default_page_size; 3321 _page_sizes[2] = 0; 3322 } 3323 3324 return _large_page_size; 3325 } 3326 3327 bool os::Linux::setup_large_page_type(size_t page_size) { 3328 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3329 FLAG_IS_DEFAULT(UseSHM) && 3330 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3331 3332 // The type of large pages has not been specified by the user. 3333 3334 // Try UseHugeTLBFS and then UseSHM. 3335 UseHugeTLBFS = UseSHM = true; 3336 3337 // Don't try UseTransparentHugePages since there are known 3338 // performance issues with it turned on. This might change in the future. 3339 UseTransparentHugePages = false; 3340 } 3341 3342 if (UseTransparentHugePages) { 3343 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3344 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3345 UseHugeTLBFS = false; 3346 UseSHM = false; 3347 return true; 3348 } 3349 UseTransparentHugePages = false; 3350 } 3351 3352 if (UseHugeTLBFS) { 3353 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3354 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3355 UseSHM = false; 3356 return true; 3357 } 3358 UseHugeTLBFS = false; 3359 } 3360 3361 return UseSHM; 3362 } 3363 3364 void os::large_page_init() { 3365 if (!UseLargePages && 3366 !UseTransparentHugePages && 3367 !UseHugeTLBFS && 3368 !UseSHM) { 3369 // Not using large pages. 3370 return; 3371 } 3372 3373 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3374 // The user explicitly turned off large pages. 3375 // Ignore the rest of the large pages flags. 3376 UseTransparentHugePages = false; 3377 UseHugeTLBFS = false; 3378 UseSHM = false; 3379 return; 3380 } 3381 3382 size_t large_page_size = Linux::setup_large_page_size(); 3383 UseLargePages = Linux::setup_large_page_type(large_page_size); 3384 3385 set_coredump_filter(); 3386 } 3387 3388 #ifndef SHM_HUGETLB 3389 #define SHM_HUGETLB 04000 3390 #endif 3391 3392 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, 3393 char* req_addr, bool exec) { 3394 // "exec" is passed in but not used. Creating the shared image for 3395 // the code cache doesn't have an SHM_X executable permission to check. 3396 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3397 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3398 3399 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3400 return NULL; // Fallback to small pages. 3401 } 3402 3403 key_t key = IPC_PRIVATE; 3404 char *addr; 3405 3406 bool warn_on_failure = UseLargePages && 3407 (!FLAG_IS_DEFAULT(UseLargePages) || 3408 !FLAG_IS_DEFAULT(UseSHM) || 3409 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3410 char msg[128]; 3411 3412 // Create a large shared memory region to attach to based on size. 3413 // Currently, size is the total size of the heap 3414 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3415 if (shmid == -1) { 3416 // Possible reasons for shmget failure: 3417 // 1. shmmax is too small for Java heap. 3418 // > check shmmax value: cat /proc/sys/kernel/shmmax 3419 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3420 // 2. not enough large page memory. 3421 // > check available large pages: cat /proc/meminfo 3422 // > increase amount of large pages: 3423 // echo new_value > /proc/sys/vm/nr_hugepages 3424 // Note 1: different Linux may use different name for this property, 3425 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3426 // Note 2: it's possible there's enough physical memory available but 3427 // they are so fragmented after a long run that they can't 3428 // coalesce into large pages. Try to reserve large pages when 3429 // the system is still "fresh". 3430 if (warn_on_failure) { 3431 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3432 warning("%s", msg); 3433 } 3434 return NULL; 3435 } 3436 3437 // attach to the region 3438 addr = (char*)shmat(shmid, req_addr, 0); 3439 int err = errno; 3440 3441 // Remove shmid. If shmat() is successful, the actual shared memory segment 3442 // will be deleted when it's detached by shmdt() or when the process 3443 // terminates. If shmat() is not successful this will remove the shared 3444 // segment immediately. 3445 shmctl(shmid, IPC_RMID, NULL); 3446 3447 if ((intptr_t)addr == -1) { 3448 if (warn_on_failure) { 3449 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3450 warning("%s", msg); 3451 } 3452 return NULL; 3453 } 3454 3455 return addr; 3456 } 3457 3458 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, 3459 int error) { 3460 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3461 3462 bool warn_on_failure = UseLargePages && 3463 (!FLAG_IS_DEFAULT(UseLargePages) || 3464 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3465 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3466 3467 if (warn_on_failure) { 3468 char msg[128]; 3469 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3470 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3471 warning("%s", msg); 3472 } 3473 } 3474 3475 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, 3476 char* req_addr, 3477 bool exec) { 3478 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3479 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3480 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3481 3482 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3483 char* addr = (char*)::mmap(req_addr, bytes, prot, 3484 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3485 -1, 0); 3486 3487 if (addr == MAP_FAILED) { 3488 warn_on_large_pages_failure(req_addr, bytes, errno); 3489 return NULL; 3490 } 3491 3492 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3493 3494 return addr; 3495 } 3496 3497 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, 3498 size_t alignment, 3499 char* req_addr, 3500 bool exec) { 3501 size_t large_page_size = os::large_page_size(); 3502 3503 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3504 3505 // Allocate small pages. 3506 3507 char* start; 3508 if (req_addr != NULL) { 3509 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3510 assert(is_size_aligned(bytes, alignment), "Must be"); 3511 start = os::reserve_memory(bytes, req_addr); 3512 assert(start == NULL || start == req_addr, "Must be"); 3513 } else { 3514 start = os::reserve_memory_aligned(bytes, alignment); 3515 } 3516 3517 if (start == NULL) { 3518 return NULL; 3519 } 3520 3521 assert(is_ptr_aligned(start, alignment), "Must be"); 3522 3523 if (MemTracker::tracking_level() > NMT_minimal) { 3524 // os::reserve_memory_special will record this memory area. 3525 // Need to release it here to prevent overlapping reservations. 3526 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3527 tkr.record((address)start, bytes); 3528 } 3529 3530 char* end = start + bytes; 3531 3532 // Find the regions of the allocated chunk that can be promoted to large pages. 3533 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3534 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3535 3536 size_t lp_bytes = lp_end - lp_start; 3537 3538 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3539 3540 if (lp_bytes == 0) { 3541 // The mapped region doesn't even span the start and the end of a large page. 3542 // Fall back to allocate a non-special area. 3543 ::munmap(start, end - start); 3544 return NULL; 3545 } 3546 3547 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3548 3549 3550 void* result; 3551 3552 if (start != lp_start) { 3553 result = ::mmap(start, lp_start - start, prot, 3554 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3555 -1, 0); 3556 if (result == MAP_FAILED) { 3557 ::munmap(lp_start, end - lp_start); 3558 return NULL; 3559 } 3560 } 3561 3562 result = ::mmap(lp_start, lp_bytes, prot, 3563 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3564 -1, 0); 3565 if (result == MAP_FAILED) { 3566 warn_on_large_pages_failure(req_addr, bytes, errno); 3567 // If the mmap above fails, the large pages region will be unmapped and we 3568 // have regions before and after with small pages. Release these regions. 3569 // 3570 // | mapped | unmapped | mapped | 3571 // ^ ^ ^ ^ 3572 // start lp_start lp_end end 3573 // 3574 ::munmap(start, lp_start - start); 3575 ::munmap(lp_end, end - lp_end); 3576 return NULL; 3577 } 3578 3579 if (lp_end != end) { 3580 result = ::mmap(lp_end, end - lp_end, prot, 3581 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3582 -1, 0); 3583 if (result == MAP_FAILED) { 3584 ::munmap(start, lp_end - start); 3585 return NULL; 3586 } 3587 } 3588 3589 return start; 3590 } 3591 3592 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, 3593 size_t alignment, 3594 char* req_addr, 3595 bool exec) { 3596 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3597 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3598 assert(is_power_of_2(alignment), "Must be"); 3599 assert(is_power_of_2(os::large_page_size()), "Must be"); 3600 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3601 3602 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3603 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3604 } else { 3605 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3606 } 3607 } 3608 3609 char* os::reserve_memory_special(size_t bytes, size_t alignment, 3610 char* req_addr, bool exec) { 3611 assert(UseLargePages, "only for large pages"); 3612 3613 char* addr; 3614 if (UseSHM) { 3615 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3616 } else { 3617 assert(UseHugeTLBFS, "must be"); 3618 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3619 } 3620 3621 if (addr != NULL) { 3622 if (UseNUMAInterleaving) { 3623 numa_make_global(addr, bytes); 3624 } 3625 3626 // The memory is committed 3627 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC); 3628 } 3629 3630 return addr; 3631 } 3632 3633 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3634 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3635 return shmdt(base) == 0; 3636 } 3637 3638 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3639 return pd_release_memory(base, bytes); 3640 } 3641 3642 bool os::release_memory_special(char* base, size_t bytes) { 3643 bool res; 3644 if (MemTracker::tracking_level() > NMT_minimal) { 3645 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3646 res = os::Linux::release_memory_special_impl(base, bytes); 3647 if (res) { 3648 tkr.record((address)base, bytes); 3649 } 3650 3651 } else { 3652 res = os::Linux::release_memory_special_impl(base, bytes); 3653 } 3654 return res; 3655 } 3656 3657 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) { 3658 assert(UseLargePages, "only for large pages"); 3659 bool res; 3660 3661 if (UseSHM) { 3662 res = os::Linux::release_memory_special_shm(base, bytes); 3663 } else { 3664 assert(UseHugeTLBFS, "must be"); 3665 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3666 } 3667 return res; 3668 } 3669 3670 size_t os::large_page_size() { 3671 return _large_page_size; 3672 } 3673 3674 // With SysV SHM the entire memory region must be allocated as shared 3675 // memory. 3676 // HugeTLBFS allows application to commit large page memory on demand. 3677 // However, when committing memory with HugeTLBFS fails, the region 3678 // that was supposed to be committed will lose the old reservation 3679 // and allow other threads to steal that memory region. Because of this 3680 // behavior we can't commit HugeTLBFS memory. 3681 bool os::can_commit_large_page_memory() { 3682 return UseTransparentHugePages; 3683 } 3684 3685 bool os::can_execute_large_page_memory() { 3686 return UseTransparentHugePages || UseHugeTLBFS; 3687 } 3688 3689 // Reserve memory at an arbitrary address, only if that area is 3690 // available (and not reserved for something else). 3691 3692 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3693 const int max_tries = 10; 3694 char* base[max_tries]; 3695 size_t size[max_tries]; 3696 const size_t gap = 0x000000; 3697 3698 // Assert only that the size is a multiple of the page size, since 3699 // that's all that mmap requires, and since that's all we really know 3700 // about at this low abstraction level. If we need higher alignment, 3701 // we can either pass an alignment to this method or verify alignment 3702 // in one of the methods further up the call chain. See bug 5044738. 3703 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3704 3705 // Repeatedly allocate blocks until the block is allocated at the 3706 // right spot. Give up after max_tries. Note that reserve_memory() will 3707 // automatically update _highest_vm_reserved_address if the call is 3708 // successful. The variable tracks the highest memory address every reserved 3709 // by JVM. It is used to detect heap-stack collision if running with 3710 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3711 // space than needed, it could confuse the collision detecting code. To 3712 // solve the problem, save current _highest_vm_reserved_address and 3713 // calculate the correct value before return. 3714 address old_highest = _highest_vm_reserved_address; 3715 3716 // Linux mmap allows caller to pass an address as hint; give it a try first, 3717 // if kernel honors the hint then we can return immediately. 3718 char * addr = anon_mmap(requested_addr, bytes, false); 3719 if (addr == requested_addr) { 3720 return requested_addr; 3721 } 3722 3723 if (addr != NULL) { 3724 // mmap() is successful but it fails to reserve at the requested address 3725 anon_munmap(addr, bytes); 3726 } 3727 3728 int i; 3729 for (i = 0; i < max_tries; ++i) { 3730 base[i] = reserve_memory(bytes); 3731 3732 if (base[i] != NULL) { 3733 // Is this the block we wanted? 3734 if (base[i] == requested_addr) { 3735 size[i] = bytes; 3736 break; 3737 } 3738 3739 // Does this overlap the block we wanted? Give back the overlapped 3740 // parts and try again. 3741 3742 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3743 if (top_overlap >= 0 && top_overlap < bytes) { 3744 unmap_memory(base[i], top_overlap); 3745 base[i] += top_overlap; 3746 size[i] = bytes - top_overlap; 3747 } else { 3748 size_t bottom_overlap = base[i] + bytes - requested_addr; 3749 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3750 unmap_memory(requested_addr, bottom_overlap); 3751 size[i] = bytes - bottom_overlap; 3752 } else { 3753 size[i] = bytes; 3754 } 3755 } 3756 } 3757 } 3758 3759 // Give back the unused reserved pieces. 3760 3761 for (int j = 0; j < i; ++j) { 3762 if (base[j] != NULL) { 3763 unmap_memory(base[j], size[j]); 3764 } 3765 } 3766 3767 if (i < max_tries) { 3768 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3769 return requested_addr; 3770 } else { 3771 _highest_vm_reserved_address = old_highest; 3772 return NULL; 3773 } 3774 } 3775 3776 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3777 return ::read(fd, buf, nBytes); 3778 } 3779 3780 size_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) { 3781 return ::pread(fd, buf, nBytes, offset); 3782 } 3783 3784 // Short sleep, direct OS call. 3785 // 3786 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee 3787 // sched_yield(2) will actually give up the CPU: 3788 // 3789 // * Alone on this pariticular CPU, keeps running. 3790 // * Before the introduction of "skip_buddy" with "compat_yield" disabled 3791 // (pre 2.6.39). 3792 // 3793 // So calling this with 0 is an alternative. 3794 // 3795 void os::naked_short_sleep(jlong ms) { 3796 struct timespec req; 3797 3798 assert(ms < 1000, "Un-interruptable sleep, short time use only"); 3799 req.tv_sec = 0; 3800 if (ms > 0) { 3801 req.tv_nsec = (ms % 1000) * 1000000; 3802 } else { 3803 req.tv_nsec = 1; 3804 } 3805 3806 nanosleep(&req, NULL); 3807 3808 return; 3809 } 3810 3811 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3812 void os::infinite_sleep() { 3813 while (true) { // sleep forever ... 3814 ::sleep(100); // ... 100 seconds at a time 3815 } 3816 } 3817 3818 // Used to convert frequent JVM_Yield() to nops 3819 bool os::dont_yield() { 3820 return DontYieldALot; 3821 } 3822 3823 void os::naked_yield() { 3824 sched_yield(); 3825 } 3826 3827 //////////////////////////////////////////////////////////////////////////////// 3828 // thread priority support 3829 3830 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3831 // only supports dynamic priority, static priority must be zero. For real-time 3832 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3833 // However, for large multi-threaded applications, SCHED_RR is not only slower 3834 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3835 // of 5 runs - Sep 2005). 3836 // 3837 // The following code actually changes the niceness of kernel-thread/LWP. It 3838 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3839 // not the entire user process, and user level threads are 1:1 mapped to kernel 3840 // threads. It has always been the case, but could change in the future. For 3841 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3842 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3843 3844 int os::java_to_os_priority[CriticalPriority + 1] = { 3845 19, // 0 Entry should never be used 3846 3847 4, // 1 MinPriority 3848 3, // 2 3849 2, // 3 3850 3851 1, // 4 3852 0, // 5 NormPriority 3853 -1, // 6 3854 3855 -2, // 7 3856 -3, // 8 3857 -4, // 9 NearMaxPriority 3858 3859 -5, // 10 MaxPriority 3860 3861 -5 // 11 CriticalPriority 3862 }; 3863 3864 static int prio_init() { 3865 if (ThreadPriorityPolicy == 1) { 3866 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3867 // if effective uid is not root. Perhaps, a more elegant way of doing 3868 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3869 if (geteuid() != 0) { 3870 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3871 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3872 } 3873 ThreadPriorityPolicy = 0; 3874 } 3875 } 3876 if (UseCriticalJavaThreadPriority) { 3877 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3878 } 3879 return 0; 3880 } 3881 3882 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3883 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK; 3884 3885 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3886 return (ret == 0) ? OS_OK : OS_ERR; 3887 } 3888 3889 OSReturn os::get_native_priority(const Thread* const thread, 3890 int *priority_ptr) { 3891 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) { 3892 *priority_ptr = java_to_os_priority[NormPriority]; 3893 return OS_OK; 3894 } 3895 3896 errno = 0; 3897 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3898 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3899 } 3900 3901 // Hint to the underlying OS that a task switch would not be good. 3902 // Void return because it's a hint and can fail. 3903 void os::hint_no_preempt() {} 3904 3905 //////////////////////////////////////////////////////////////////////////////// 3906 // suspend/resume support 3907 3908 // the low-level signal-based suspend/resume support is a remnant from the 3909 // old VM-suspension that used to be for java-suspension, safepoints etc, 3910 // within hotspot. Now there is a single use-case for this: 3911 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3912 // that runs in the watcher thread. 3913 // The remaining code is greatly simplified from the more general suspension 3914 // code that used to be used. 3915 // 3916 // The protocol is quite simple: 3917 // - suspend: 3918 // - sends a signal to the target thread 3919 // - polls the suspend state of the osthread using a yield loop 3920 // - target thread signal handler (SR_handler) sets suspend state 3921 // and blocks in sigsuspend until continued 3922 // - resume: 3923 // - sets target osthread state to continue 3924 // - sends signal to end the sigsuspend loop in the SR_handler 3925 // 3926 // Note that the SR_lock plays no role in this suspend/resume protocol. 3927 3928 static void resume_clear_context(OSThread *osthread) { 3929 osthread->set_ucontext(NULL); 3930 osthread->set_siginfo(NULL); 3931 } 3932 3933 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, 3934 ucontext_t* context) { 3935 osthread->set_ucontext(context); 3936 osthread->set_siginfo(siginfo); 3937 } 3938 3939 // Handler function invoked when a thread's execution is suspended or 3940 // resumed. We have to be careful that only async-safe functions are 3941 // called here (Note: most pthread functions are not async safe and 3942 // should be avoided.) 3943 // 3944 // Note: sigwait() is a more natural fit than sigsuspend() from an 3945 // interface point of view, but sigwait() prevents the signal hander 3946 // from being run. libpthread would get very confused by not having 3947 // its signal handlers run and prevents sigwait()'s use with the 3948 // mutex granting granting signal. 3949 // 3950 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 3951 // 3952 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3953 // Save and restore errno to avoid confusing native code with EINTR 3954 // after sigsuspend. 3955 int old_errno = errno; 3956 3957 Thread* thread = Thread::current(); 3958 OSThread* osthread = thread->osthread(); 3959 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 3960 3961 os::SuspendResume::State current = osthread->sr.state(); 3962 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 3963 suspend_save_context(osthread, siginfo, context); 3964 3965 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 3966 os::SuspendResume::State state = osthread->sr.suspended(); 3967 if (state == os::SuspendResume::SR_SUSPENDED) { 3968 sigset_t suspend_set; // signals for sigsuspend() 3969 3970 // get current set of blocked signals and unblock resume signal 3971 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3972 sigdelset(&suspend_set, SR_signum); 3973 3974 sr_semaphore.signal(); 3975 // wait here until we are resumed 3976 while (1) { 3977 sigsuspend(&suspend_set); 3978 3979 os::SuspendResume::State result = osthread->sr.running(); 3980 if (result == os::SuspendResume::SR_RUNNING) { 3981 sr_semaphore.signal(); 3982 break; 3983 } 3984 } 3985 3986 } else if (state == os::SuspendResume::SR_RUNNING) { 3987 // request was cancelled, continue 3988 } else { 3989 ShouldNotReachHere(); 3990 } 3991 3992 resume_clear_context(osthread); 3993 } else if (current == os::SuspendResume::SR_RUNNING) { 3994 // request was cancelled, continue 3995 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 3996 // ignore 3997 } else { 3998 // ignore 3999 } 4000 4001 errno = old_errno; 4002 } 4003 4004 4005 static int SR_initialize() { 4006 struct sigaction act; 4007 char *s; 4008 // Get signal number to use for suspend/resume 4009 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 4010 int sig = ::strtol(s, 0, 10); 4011 if (sig > 0 || sig < _NSIG) { 4012 SR_signum = sig; 4013 } 4014 } 4015 4016 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 4017 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 4018 4019 sigemptyset(&SR_sigset); 4020 sigaddset(&SR_sigset, SR_signum); 4021 4022 // Set up signal handler for suspend/resume 4023 act.sa_flags = SA_RESTART|SA_SIGINFO; 4024 act.sa_handler = (void (*)(int)) SR_handler; 4025 4026 // SR_signum is blocked by default. 4027 // 4528190 - We also need to block pthread restart signal (32 on all 4028 // supported Linux platforms). Note that LinuxThreads need to block 4029 // this signal for all threads to work properly. So we don't have 4030 // to use hard-coded signal number when setting up the mask. 4031 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4032 4033 if (sigaction(SR_signum, &act, 0) == -1) { 4034 return -1; 4035 } 4036 4037 // Save signal flag 4038 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4039 return 0; 4040 } 4041 4042 static int sr_notify(OSThread* osthread) { 4043 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4044 assert_status(status == 0, status, "pthread_kill"); 4045 return status; 4046 } 4047 4048 // "Randomly" selected value for how long we want to spin 4049 // before bailing out on suspending a thread, also how often 4050 // we send a signal to a thread we want to resume 4051 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4052 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4053 4054 // returns true on success and false on error - really an error is fatal 4055 // but this seems the normal response to library errors 4056 static bool do_suspend(OSThread* osthread) { 4057 assert(osthread->sr.is_running(), "thread should be running"); 4058 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4059 4060 // mark as suspended and send signal 4061 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4062 // failed to switch, state wasn't running? 4063 ShouldNotReachHere(); 4064 return false; 4065 } 4066 4067 if (sr_notify(osthread) != 0) { 4068 ShouldNotReachHere(); 4069 } 4070 4071 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4072 while (true) { 4073 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4074 break; 4075 } else { 4076 // timeout 4077 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4078 if (cancelled == os::SuspendResume::SR_RUNNING) { 4079 return false; 4080 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4081 // make sure that we consume the signal on the semaphore as well 4082 sr_semaphore.wait(); 4083 break; 4084 } else { 4085 ShouldNotReachHere(); 4086 return false; 4087 } 4088 } 4089 } 4090 4091 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4092 return true; 4093 } 4094 4095 static void do_resume(OSThread* osthread) { 4096 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4097 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4098 4099 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4100 // failed to switch to WAKEUP_REQUEST 4101 ShouldNotReachHere(); 4102 return; 4103 } 4104 4105 while (true) { 4106 if (sr_notify(osthread) == 0) { 4107 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4108 if (osthread->sr.is_running()) { 4109 return; 4110 } 4111 } 4112 } else { 4113 ShouldNotReachHere(); 4114 } 4115 } 4116 4117 guarantee(osthread->sr.is_running(), "Must be running!"); 4118 } 4119 4120 /////////////////////////////////////////////////////////////////////////////////// 4121 // signal handling (except suspend/resume) 4122 4123 // This routine may be used by user applications as a "hook" to catch signals. 4124 // The user-defined signal handler must pass unrecognized signals to this 4125 // routine, and if it returns true (non-zero), then the signal handler must 4126 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4127 // routine will never retun false (zero), but instead will execute a VM panic 4128 // routine kill the process. 4129 // 4130 // If this routine returns false, it is OK to call it again. This allows 4131 // the user-defined signal handler to perform checks either before or after 4132 // the VM performs its own checks. Naturally, the user code would be making 4133 // a serious error if it tried to handle an exception (such as a null check 4134 // or breakpoint) that the VM was generating for its own correct operation. 4135 // 4136 // This routine may recognize any of the following kinds of signals: 4137 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4138 // It should be consulted by handlers for any of those signals. 4139 // 4140 // The caller of this routine must pass in the three arguments supplied 4141 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4142 // field of the structure passed to sigaction(). This routine assumes that 4143 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4144 // 4145 // Note that the VM will print warnings if it detects conflicting signal 4146 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4147 // 4148 extern "C" JNIEXPORT int JVM_handle_linux_signal(int signo, 4149 siginfo_t* siginfo, 4150 void* ucontext, 4151 int abort_if_unrecognized); 4152 4153 void signalHandler(int sig, siginfo_t* info, void* uc) { 4154 assert(info != NULL && uc != NULL, "it must be old kernel"); 4155 int orig_errno = errno; // Preserve errno value over signal handler. 4156 JVM_handle_linux_signal(sig, info, uc, true); 4157 errno = orig_errno; 4158 } 4159 4160 4161 // This boolean allows users to forward their own non-matching signals 4162 // to JVM_handle_linux_signal, harmlessly. 4163 bool os::Linux::signal_handlers_are_installed = false; 4164 4165 // For signal-chaining 4166 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4167 unsigned int os::Linux::sigs = 0; 4168 bool os::Linux::libjsig_is_loaded = false; 4169 typedef struct sigaction *(*get_signal_t)(int); 4170 get_signal_t os::Linux::get_signal_action = NULL; 4171 4172 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4173 struct sigaction *actp = NULL; 4174 4175 if (libjsig_is_loaded) { 4176 // Retrieve the old signal handler from libjsig 4177 actp = (*get_signal_action)(sig); 4178 } 4179 if (actp == NULL) { 4180 // Retrieve the preinstalled signal handler from jvm 4181 actp = get_preinstalled_handler(sig); 4182 } 4183 4184 return actp; 4185 } 4186 4187 static bool call_chained_handler(struct sigaction *actp, int sig, 4188 siginfo_t *siginfo, void *context) { 4189 // Call the old signal handler 4190 if (actp->sa_handler == SIG_DFL) { 4191 // It's more reasonable to let jvm treat it as an unexpected exception 4192 // instead of taking the default action. 4193 return false; 4194 } else if (actp->sa_handler != SIG_IGN) { 4195 if ((actp->sa_flags & SA_NODEFER) == 0) { 4196 // automaticlly block the signal 4197 sigaddset(&(actp->sa_mask), sig); 4198 } 4199 4200 sa_handler_t hand; 4201 sa_sigaction_t sa; 4202 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4203 // retrieve the chained handler 4204 if (siginfo_flag_set) { 4205 sa = actp->sa_sigaction; 4206 } else { 4207 hand = actp->sa_handler; 4208 } 4209 4210 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4211 actp->sa_handler = SIG_DFL; 4212 } 4213 4214 // try to honor the signal mask 4215 sigset_t oset; 4216 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4217 4218 // call into the chained handler 4219 if (siginfo_flag_set) { 4220 (*sa)(sig, siginfo, context); 4221 } else { 4222 (*hand)(sig); 4223 } 4224 4225 // restore the signal mask 4226 pthread_sigmask(SIG_SETMASK, &oset, 0); 4227 } 4228 // Tell jvm's signal handler the signal is taken care of. 4229 return true; 4230 } 4231 4232 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4233 bool chained = false; 4234 // signal-chaining 4235 if (UseSignalChaining) { 4236 struct sigaction *actp = get_chained_signal_action(sig); 4237 if (actp != NULL) { 4238 chained = call_chained_handler(actp, sig, siginfo, context); 4239 } 4240 } 4241 return chained; 4242 } 4243 4244 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4245 if ((((unsigned int)1 << sig) & sigs) != 0) { 4246 return &sigact[sig]; 4247 } 4248 return NULL; 4249 } 4250 4251 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4252 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4253 sigact[sig] = oldAct; 4254 sigs |= (unsigned int)1 << sig; 4255 } 4256 4257 // for diagnostic 4258 int os::Linux::sigflags[MAXSIGNUM]; 4259 4260 int os::Linux::get_our_sigflags(int sig) { 4261 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4262 return sigflags[sig]; 4263 } 4264 4265 void os::Linux::set_our_sigflags(int sig, int flags) { 4266 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4267 sigflags[sig] = flags; 4268 } 4269 4270 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4271 // Check for overwrite. 4272 struct sigaction oldAct; 4273 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4274 4275 void* oldhand = oldAct.sa_sigaction 4276 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4277 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4278 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4279 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4280 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4281 if (AllowUserSignalHandlers || !set_installed) { 4282 // Do not overwrite; user takes responsibility to forward to us. 4283 return; 4284 } else if (UseSignalChaining) { 4285 // save the old handler in jvm 4286 save_preinstalled_handler(sig, oldAct); 4287 // libjsig also interposes the sigaction() call below and saves the 4288 // old sigaction on it own. 4289 } else { 4290 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4291 "%#lx for signal %d.", (long)oldhand, sig)); 4292 } 4293 } 4294 4295 struct sigaction sigAct; 4296 sigfillset(&(sigAct.sa_mask)); 4297 sigAct.sa_handler = SIG_DFL; 4298 if (!set_installed) { 4299 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4300 } else { 4301 sigAct.sa_sigaction = signalHandler; 4302 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4303 } 4304 // Save flags, which are set by ours 4305 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4306 sigflags[sig] = sigAct.sa_flags; 4307 4308 int ret = sigaction(sig, &sigAct, &oldAct); 4309 assert(ret == 0, "check"); 4310 4311 void* oldhand2 = oldAct.sa_sigaction 4312 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4313 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4314 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4315 } 4316 4317 // install signal handlers for signals that HotSpot needs to 4318 // handle in order to support Java-level exception handling. 4319 4320 void os::Linux::install_signal_handlers() { 4321 if (!signal_handlers_are_installed) { 4322 signal_handlers_are_installed = true; 4323 4324 // signal-chaining 4325 typedef void (*signal_setting_t)(); 4326 signal_setting_t begin_signal_setting = NULL; 4327 signal_setting_t end_signal_setting = NULL; 4328 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4329 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4330 if (begin_signal_setting != NULL) { 4331 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4332 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4333 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4334 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4335 libjsig_is_loaded = true; 4336 assert(UseSignalChaining, "should enable signal-chaining"); 4337 } 4338 if (libjsig_is_loaded) { 4339 // Tell libjsig jvm is setting signal handlers 4340 (*begin_signal_setting)(); 4341 } 4342 4343 set_signal_handler(SIGSEGV, true); 4344 set_signal_handler(SIGPIPE, true); 4345 set_signal_handler(SIGBUS, true); 4346 set_signal_handler(SIGILL, true); 4347 set_signal_handler(SIGFPE, true); 4348 #if defined(PPC64) 4349 set_signal_handler(SIGTRAP, true); 4350 #endif 4351 set_signal_handler(SIGXFSZ, true); 4352 4353 if (libjsig_is_loaded) { 4354 // Tell libjsig jvm finishes setting signal handlers 4355 (*end_signal_setting)(); 4356 } 4357 4358 // We don't activate signal checker if libjsig is in place, we trust ourselves 4359 // and if UserSignalHandler is installed all bets are off. 4360 // Log that signal checking is off only if -verbose:jni is specified. 4361 if (CheckJNICalls) { 4362 if (libjsig_is_loaded) { 4363 if (PrintJNIResolving) { 4364 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4365 } 4366 check_signals = false; 4367 } 4368 if (AllowUserSignalHandlers) { 4369 if (PrintJNIResolving) { 4370 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4371 } 4372 check_signals = false; 4373 } 4374 } 4375 } 4376 } 4377 4378 // This is the fastest way to get thread cpu time on Linux. 4379 // Returns cpu time (user+sys) for any thread, not only for current. 4380 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4381 // It might work on 2.6.10+ with a special kernel/glibc patch. 4382 // For reference, please, see IEEE Std 1003.1-2004: 4383 // http://www.unix.org/single_unix_specification 4384 4385 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4386 struct timespec tp; 4387 int rc = os::Linux::clock_gettime(clockid, &tp); 4388 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4389 4390 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4391 } 4392 4393 ///// 4394 // glibc on Linux platform uses non-documented flag 4395 // to indicate, that some special sort of signal 4396 // trampoline is used. 4397 // We will never set this flag, and we should 4398 // ignore this flag in our diagnostic 4399 #ifdef SIGNIFICANT_SIGNAL_MASK 4400 #undef SIGNIFICANT_SIGNAL_MASK 4401 #endif 4402 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4403 4404 static const char* get_signal_handler_name(address handler, 4405 char* buf, int buflen) { 4406 int offset; 4407 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4408 if (found) { 4409 // skip directory names 4410 const char *p1, *p2; 4411 p1 = buf; 4412 size_t len = strlen(os::file_separator()); 4413 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4414 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4415 } else { 4416 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4417 } 4418 return buf; 4419 } 4420 4421 static void print_signal_handler(outputStream* st, int sig, 4422 char* buf, size_t buflen) { 4423 struct sigaction sa; 4424 4425 sigaction(sig, NULL, &sa); 4426 4427 // See comment for SIGNIFICANT_SIGNAL_MASK define 4428 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4429 4430 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4431 4432 address handler = (sa.sa_flags & SA_SIGINFO) 4433 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4434 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4435 4436 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4437 st->print("SIG_DFL"); 4438 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4439 st->print("SIG_IGN"); 4440 } else { 4441 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4442 } 4443 4444 st->print(", sa_mask[0]="); 4445 os::Posix::print_signal_set_short(st, &sa.sa_mask); 4446 4447 address rh = VMError::get_resetted_sighandler(sig); 4448 // May be, handler was resetted by VMError? 4449 if (rh != NULL) { 4450 handler = rh; 4451 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4452 } 4453 4454 st->print(", sa_flags="); 4455 os::Posix::print_sa_flags(st, sa.sa_flags); 4456 4457 // Check: is it our handler? 4458 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4459 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4460 // It is our signal handler 4461 // check for flags, reset system-used one! 4462 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4463 st->print( 4464 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4465 os::Linux::get_our_sigflags(sig)); 4466 } 4467 } 4468 st->cr(); 4469 } 4470 4471 4472 #define DO_SIGNAL_CHECK(sig) \ 4473 do { \ 4474 if (!sigismember(&check_signal_done, sig)) { \ 4475 os::Linux::check_signal_handler(sig); \ 4476 } \ 4477 } while (0) 4478 4479 // This method is a periodic task to check for misbehaving JNI applications 4480 // under CheckJNI, we can add any periodic checks here 4481 4482 void os::run_periodic_checks() { 4483 if (check_signals == false) return; 4484 4485 // SEGV and BUS if overridden could potentially prevent 4486 // generation of hs*.log in the event of a crash, debugging 4487 // such a case can be very challenging, so we absolutely 4488 // check the following for a good measure: 4489 DO_SIGNAL_CHECK(SIGSEGV); 4490 DO_SIGNAL_CHECK(SIGILL); 4491 DO_SIGNAL_CHECK(SIGFPE); 4492 DO_SIGNAL_CHECK(SIGBUS); 4493 DO_SIGNAL_CHECK(SIGPIPE); 4494 DO_SIGNAL_CHECK(SIGXFSZ); 4495 #if defined(PPC64) 4496 DO_SIGNAL_CHECK(SIGTRAP); 4497 #endif 4498 4499 // ReduceSignalUsage allows the user to override these handlers 4500 // see comments at the very top and jvm_solaris.h 4501 if (!ReduceSignalUsage) { 4502 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4503 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4504 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4505 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4506 } 4507 4508 DO_SIGNAL_CHECK(SR_signum); 4509 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4510 } 4511 4512 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4513 4514 static os_sigaction_t os_sigaction = NULL; 4515 4516 void os::Linux::check_signal_handler(int sig) { 4517 char buf[O_BUFLEN]; 4518 address jvmHandler = NULL; 4519 4520 4521 struct sigaction act; 4522 if (os_sigaction == NULL) { 4523 // only trust the default sigaction, in case it has been interposed 4524 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4525 if (os_sigaction == NULL) return; 4526 } 4527 4528 os_sigaction(sig, (struct sigaction*)NULL, &act); 4529 4530 4531 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4532 4533 address thisHandler = (act.sa_flags & SA_SIGINFO) 4534 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4535 : CAST_FROM_FN_PTR(address, act.sa_handler); 4536 4537 4538 switch (sig) { 4539 case SIGSEGV: 4540 case SIGBUS: 4541 case SIGFPE: 4542 case SIGPIPE: 4543 case SIGILL: 4544 case SIGXFSZ: 4545 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4546 break; 4547 4548 case SHUTDOWN1_SIGNAL: 4549 case SHUTDOWN2_SIGNAL: 4550 case SHUTDOWN3_SIGNAL: 4551 case BREAK_SIGNAL: 4552 jvmHandler = (address)user_handler(); 4553 break; 4554 4555 case INTERRUPT_SIGNAL: 4556 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4557 break; 4558 4559 default: 4560 if (sig == SR_signum) { 4561 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4562 } else { 4563 return; 4564 } 4565 break; 4566 } 4567 4568 if (thisHandler != jvmHandler) { 4569 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4570 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4571 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4572 // No need to check this sig any longer 4573 sigaddset(&check_signal_done, sig); 4574 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN 4575 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) { 4576 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell", 4577 exception_name(sig, buf, O_BUFLEN)); 4578 } 4579 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4580 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4581 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4582 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4583 // No need to check this sig any longer 4584 sigaddset(&check_signal_done, sig); 4585 } 4586 4587 // Dump all the signal 4588 if (sigismember(&check_signal_done, sig)) { 4589 print_signal_handlers(tty, buf, O_BUFLEN); 4590 } 4591 } 4592 4593 extern void report_error(char* file_name, int line_no, char* title, 4594 char* format, ...); 4595 4596 extern bool signal_name(int signo, char* buf, size_t len); 4597 4598 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4599 if (0 < exception_code && exception_code <= SIGRTMAX) { 4600 // signal 4601 if (!signal_name(exception_code, buf, size)) { 4602 jio_snprintf(buf, size, "SIG%d", exception_code); 4603 } 4604 return buf; 4605 } else { 4606 return NULL; 4607 } 4608 } 4609 4610 // this is called _before_ the most of global arguments have been parsed 4611 void os::init(void) { 4612 char dummy; // used to get a guess on initial stack address 4613 // first_hrtime = gethrtime(); 4614 4615 // With LinuxThreads the JavaMain thread pid (primordial thread) 4616 // is different than the pid of the java launcher thread. 4617 // So, on Linux, the launcher thread pid is passed to the VM 4618 // via the sun.java.launcher.pid property. 4619 // Use this property instead of getpid() if it was correctly passed. 4620 // See bug 6351349. 4621 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4622 4623 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4624 4625 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4626 4627 init_random(1234567); 4628 4629 ThreadCritical::initialize(); 4630 4631 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4632 if (Linux::page_size() == -1) { 4633 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4634 strerror(errno))); 4635 } 4636 init_page_sizes((size_t) Linux::page_size()); 4637 4638 Linux::initialize_system_info(); 4639 4640 // main_thread points to the aboriginal thread 4641 Linux::_main_thread = pthread_self(); 4642 4643 Linux::clock_init(); 4644 initial_time_count = javaTimeNanos(); 4645 4646 // pthread_condattr initialization for monotonic clock 4647 int status; 4648 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4649 if ((status = pthread_condattr_init(_condattr)) != 0) { 4650 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4651 } 4652 // Only set the clock if CLOCK_MONOTONIC is available 4653 if (os::supports_monotonic_clock()) { 4654 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4655 if (status == EINVAL) { 4656 warning("Unable to use monotonic clock with relative timed-waits" \ 4657 " - changes to the time-of-day clock may have adverse affects"); 4658 } else { 4659 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4660 } 4661 } 4662 } 4663 // else it defaults to CLOCK_REALTIME 4664 4665 pthread_mutex_init(&dl_mutex, NULL); 4666 4667 // If the pagesize of the VM is greater than 8K determine the appropriate 4668 // number of initial guard pages. The user can change this with the 4669 // command line arguments, if needed. 4670 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4671 StackYellowPages = 1; 4672 StackRedPages = 1; 4673 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4674 } 4675 4676 // retrieve entry point for pthread_setname_np 4677 Linux::_pthread_setname_np = 4678 (int(*)(pthread_t, const char*))dlsym(RTLD_DEFAULT, "pthread_setname_np"); 4679 4680 } 4681 4682 // To install functions for atexit system call 4683 extern "C" { 4684 static void perfMemory_exit_helper() { 4685 perfMemory_exit(); 4686 } 4687 } 4688 4689 // this is called _after_ the global arguments have been parsed 4690 jint os::init_2(void) { 4691 Linux::fast_thread_clock_init(); 4692 4693 // Allocate a single page and mark it as readable for safepoint polling 4694 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4695 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page"); 4696 4697 os::set_polling_page(polling_page); 4698 4699 #ifndef PRODUCT 4700 if (Verbose && PrintMiscellaneous) { 4701 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", 4702 (intptr_t)polling_page); 4703 } 4704 #endif 4705 4706 if (!UseMembar) { 4707 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4708 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4709 os::set_memory_serialize_page(mem_serialize_page); 4710 4711 #ifndef PRODUCT 4712 if (Verbose && PrintMiscellaneous) { 4713 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", 4714 (intptr_t)mem_serialize_page); 4715 } 4716 #endif 4717 } 4718 4719 // initialize suspend/resume support - must do this before signal_sets_init() 4720 if (SR_initialize() != 0) { 4721 perror("SR_initialize failed"); 4722 return JNI_ERR; 4723 } 4724 4725 Linux::signal_sets_init(); 4726 Linux::install_signal_handlers(); 4727 4728 // Check minimum allowable stack size for thread creation and to initialize 4729 // the java system classes, including StackOverflowError - depends on page 4730 // size. Add a page for compiler2 recursion in main thread. 4731 // Add in 2*BytesPerWord times page size to account for VM stack during 4732 // class initialization depending on 32 or 64 bit VM. 4733 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4734 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4735 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4736 4737 size_t threadStackSizeInBytes = ThreadStackSize * K; 4738 if (threadStackSizeInBytes != 0 && 4739 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4740 tty->print_cr("\nThe stack size specified is too small, " 4741 "Specify at least %dk", 4742 os::Linux::min_stack_allowed/ K); 4743 return JNI_ERR; 4744 } 4745 4746 // Make the stack size a multiple of the page size so that 4747 // the yellow/red zones can be guarded. 4748 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4749 vm_page_size())); 4750 4751 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4752 4753 #if defined(IA32) 4754 workaround_expand_exec_shield_cs_limit(); 4755 #endif 4756 4757 Linux::libpthread_init(); 4758 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4759 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4760 Linux::glibc_version(), Linux::libpthread_version(), 4761 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4762 } 4763 4764 if (UseNUMA) { 4765 if (!Linux::libnuma_init()) { 4766 UseNUMA = false; 4767 } else { 4768 if ((Linux::numa_max_node() < 1)) { 4769 // There's only one node(they start from 0), disable NUMA. 4770 UseNUMA = false; 4771 } 4772 } 4773 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4774 // we can make the adaptive lgrp chunk resizing work. If the user specified 4775 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4776 // disable adaptive resizing. 4777 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4778 if (FLAG_IS_DEFAULT(UseNUMA)) { 4779 UseNUMA = false; 4780 } else { 4781 if (FLAG_IS_DEFAULT(UseLargePages) && 4782 FLAG_IS_DEFAULT(UseSHM) && 4783 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4784 UseLargePages = false; 4785 } else { 4786 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4787 UseAdaptiveSizePolicy = false; 4788 UseAdaptiveNUMAChunkSizing = false; 4789 } 4790 } 4791 } 4792 if (!UseNUMA && ForceNUMA) { 4793 UseNUMA = true; 4794 } 4795 } 4796 4797 if (MaxFDLimit) { 4798 // set the number of file descriptors to max. print out error 4799 // if getrlimit/setrlimit fails but continue regardless. 4800 struct rlimit nbr_files; 4801 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4802 if (status != 0) { 4803 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4804 perror("os::init_2 getrlimit failed"); 4805 } 4806 } else { 4807 nbr_files.rlim_cur = nbr_files.rlim_max; 4808 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4809 if (status != 0) { 4810 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4811 perror("os::init_2 setrlimit failed"); 4812 } 4813 } 4814 } 4815 } 4816 4817 // Initialize lock used to serialize thread creation (see os::create_thread) 4818 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4819 4820 // at-exit methods are called in the reverse order of their registration. 4821 // atexit functions are called on return from main or as a result of a 4822 // call to exit(3C). There can be only 32 of these functions registered 4823 // and atexit() does not set errno. 4824 4825 if (PerfAllowAtExitRegistration) { 4826 // only register atexit functions if PerfAllowAtExitRegistration is set. 4827 // atexit functions can be delayed until process exit time, which 4828 // can be problematic for embedded VM situations. Embedded VMs should 4829 // call DestroyJavaVM() to assure that VM resources are released. 4830 4831 // note: perfMemory_exit_helper atexit function may be removed in 4832 // the future if the appropriate cleanup code can be added to the 4833 // VM_Exit VMOperation's doit method. 4834 if (atexit(perfMemory_exit_helper) != 0) { 4835 warning("os::init_2 atexit(perfMemory_exit_helper) failed"); 4836 } 4837 } 4838 4839 // initialize thread priority policy 4840 prio_init(); 4841 4842 return JNI_OK; 4843 } 4844 4845 // Mark the polling page as unreadable 4846 void os::make_polling_page_unreadable(void) { 4847 if (!guard_memory((char*)_polling_page, Linux::page_size())) { 4848 fatal("Could not disable polling page"); 4849 } 4850 } 4851 4852 // Mark the polling page as readable 4853 void os::make_polling_page_readable(void) { 4854 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4855 fatal("Could not enable polling page"); 4856 } 4857 } 4858 4859 int os::active_processor_count() { 4860 // Linux doesn't yet have a (official) notion of processor sets, 4861 // so just return the number of online processors. 4862 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4863 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4864 return online_cpus; 4865 } 4866 4867 void os::set_native_thread_name(const char *name) { 4868 if (Linux::_pthread_setname_np) { 4869 char buf [16]; // according to glibc manpage, 16 chars incl. '/0' 4870 snprintf(buf, sizeof(buf), "%s", name); 4871 buf[sizeof(buf) - 1] = '\0'; 4872 const int rc = Linux::_pthread_setname_np(pthread_self(), buf); 4873 // ERANGE should not happen; all other errors should just be ignored. 4874 assert(rc != ERANGE, "pthread_setname_np failed"); 4875 } 4876 } 4877 4878 bool os::distribute_processes(uint length, uint* distribution) { 4879 // Not yet implemented. 4880 return false; 4881 } 4882 4883 bool os::bind_to_processor(uint processor_id) { 4884 // Not yet implemented. 4885 return false; 4886 } 4887 4888 /// 4889 4890 void os::SuspendedThreadTask::internal_do_task() { 4891 if (do_suspend(_thread->osthread())) { 4892 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4893 do_task(context); 4894 do_resume(_thread->osthread()); 4895 } 4896 } 4897 4898 class PcFetcher : public os::SuspendedThreadTask { 4899 public: 4900 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4901 ExtendedPC result(); 4902 protected: 4903 void do_task(const os::SuspendedThreadTaskContext& context); 4904 private: 4905 ExtendedPC _epc; 4906 }; 4907 4908 ExtendedPC PcFetcher::result() { 4909 guarantee(is_done(), "task is not done yet."); 4910 return _epc; 4911 } 4912 4913 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 4914 Thread* thread = context.thread(); 4915 OSThread* osthread = thread->osthread(); 4916 if (osthread->ucontext() != NULL) { 4917 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 4918 } else { 4919 // NULL context is unexpected, double-check this is the VMThread 4920 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4921 } 4922 } 4923 4924 // Suspends the target using the signal mechanism and then grabs the PC before 4925 // resuming the target. Used by the flat-profiler only 4926 ExtendedPC os::get_thread_pc(Thread* thread) { 4927 // Make sure that it is called by the watcher for the VMThread 4928 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4929 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4930 4931 PcFetcher fetcher(thread); 4932 fetcher.run(); 4933 return fetcher.result(); 4934 } 4935 4936 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, 4937 pthread_mutex_t *_mutex, 4938 const struct timespec *_abstime) { 4939 if (is_NPTL()) { 4940 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4941 } else { 4942 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4943 // word back to default 64bit precision if condvar is signaled. Java 4944 // wants 53bit precision. Save and restore current value. 4945 int fpu = get_fpu_control_word(); 4946 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4947 set_fpu_control_word(fpu); 4948 return status; 4949 } 4950 } 4951 4952 //////////////////////////////////////////////////////////////////////////////// 4953 // debug support 4954 4955 bool os::find(address addr, outputStream* st) { 4956 Dl_info dlinfo; 4957 memset(&dlinfo, 0, sizeof(dlinfo)); 4958 if (dladdr(addr, &dlinfo) != 0) { 4959 st->print(PTR_FORMAT ": ", addr); 4960 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 4961 st->print("%s+%#x", dlinfo.dli_sname, 4962 addr - (intptr_t)dlinfo.dli_saddr); 4963 } else if (dlinfo.dli_fbase != NULL) { 4964 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4965 } else { 4966 st->print("<absolute address>"); 4967 } 4968 if (dlinfo.dli_fname != NULL) { 4969 st->print(" in %s", dlinfo.dli_fname); 4970 } 4971 if (dlinfo.dli_fbase != NULL) { 4972 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4973 } 4974 st->cr(); 4975 4976 if (Verbose) { 4977 // decode some bytes around the PC 4978 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 4979 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 4980 address lowest = (address) dlinfo.dli_sname; 4981 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4982 if (begin < lowest) begin = lowest; 4983 Dl_info dlinfo2; 4984 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 4985 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) { 4986 end = (address) dlinfo2.dli_saddr; 4987 } 4988 Disassembler::decode(begin, end, st); 4989 } 4990 return true; 4991 } 4992 return false; 4993 } 4994 4995 //////////////////////////////////////////////////////////////////////////////// 4996 // misc 4997 4998 // This does not do anything on Linux. This is basically a hook for being 4999 // able to use structured exception handling (thread-local exception filters) 5000 // on, e.g., Win32. 5001 void 5002 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 5003 JavaCallArguments* args, Thread* thread) { 5004 f(value, method, args, thread); 5005 } 5006 5007 void os::print_statistics() { 5008 } 5009 5010 int os::message_box(const char* title, const char* message) { 5011 int i; 5012 fdStream err(defaultStream::error_fd()); 5013 for (i = 0; i < 78; i++) err.print_raw("="); 5014 err.cr(); 5015 err.print_raw_cr(title); 5016 for (i = 0; i < 78; i++) err.print_raw("-"); 5017 err.cr(); 5018 err.print_raw_cr(message); 5019 for (i = 0; i < 78; i++) err.print_raw("="); 5020 err.cr(); 5021 5022 char buf[16]; 5023 // Prevent process from exiting upon "read error" without consuming all CPU 5024 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 5025 5026 return buf[0] == 'y' || buf[0] == 'Y'; 5027 } 5028 5029 int os::stat(const char *path, struct stat *sbuf) { 5030 char pathbuf[MAX_PATH]; 5031 if (strlen(path) > MAX_PATH - 1) { 5032 errno = ENAMETOOLONG; 5033 return -1; 5034 } 5035 os::native_path(strcpy(pathbuf, path)); 5036 return ::stat(pathbuf, sbuf); 5037 } 5038 5039 bool os::check_heap(bool force) { 5040 return true; 5041 } 5042 5043 // Is a (classpath) directory empty? 5044 bool os::dir_is_empty(const char* path) { 5045 DIR *dir = NULL; 5046 struct dirent *ptr; 5047 5048 dir = opendir(path); 5049 if (dir == NULL) return true; 5050 5051 // Scan the directory 5052 bool result = true; 5053 char buf[sizeof(struct dirent) + MAX_PATH]; 5054 while (result && (ptr = ::readdir(dir)) != NULL) { 5055 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5056 result = false; 5057 } 5058 } 5059 closedir(dir); 5060 return result; 5061 } 5062 5063 // This code originates from JDK's sysOpen and open64_w 5064 // from src/solaris/hpi/src/system_md.c 5065 5066 int os::open(const char *path, int oflag, int mode) { 5067 if (strlen(path) > MAX_PATH - 1) { 5068 errno = ENAMETOOLONG; 5069 return -1; 5070 } 5071 5072 // All file descriptors that are opened in the Java process and not 5073 // specifically destined for a subprocess should have the close-on-exec 5074 // flag set. If we don't set it, then careless 3rd party native code 5075 // might fork and exec without closing all appropriate file descriptors 5076 // (e.g. as we do in closeDescriptors in UNIXProcess.c), and this in 5077 // turn might: 5078 // 5079 // - cause end-of-file to fail to be detected on some file 5080 // descriptors, resulting in mysterious hangs, or 5081 // 5082 // - might cause an fopen in the subprocess to fail on a system 5083 // suffering from bug 1085341. 5084 // 5085 // (Yes, the default setting of the close-on-exec flag is a Unix 5086 // design flaw) 5087 // 5088 // See: 5089 // 1085341: 32-bit stdio routines should support file descriptors >255 5090 // 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5091 // 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5092 // 5093 // Modern Linux kernels (after 2.6.23 2007) support O_CLOEXEC with open(). 5094 // O_CLOEXEC is preferable to using FD_CLOEXEC on an open file descriptor 5095 // because it saves a system call and removes a small window where the flag 5096 // is unset. On ancient Linux kernels the O_CLOEXEC flag will be ignored 5097 // and we fall back to using FD_CLOEXEC (see below). 5098 #ifdef O_CLOEXEC 5099 oflag |= O_CLOEXEC; 5100 #endif 5101 5102 int fd = ::open64(path, oflag, mode); 5103 if (fd == -1) return -1; 5104 5105 //If the open succeeded, the file might still be a directory 5106 { 5107 struct stat64 buf64; 5108 int ret = ::fstat64(fd, &buf64); 5109 int st_mode = buf64.st_mode; 5110 5111 if (ret != -1) { 5112 if ((st_mode & S_IFMT) == S_IFDIR) { 5113 errno = EISDIR; 5114 ::close(fd); 5115 return -1; 5116 } 5117 } else { 5118 ::close(fd); 5119 return -1; 5120 } 5121 } 5122 5123 #ifdef FD_CLOEXEC 5124 // Validate that the use of the O_CLOEXEC flag on open above worked. 5125 // With recent kernels, we will perform this check exactly once. 5126 static sig_atomic_t O_CLOEXEC_is_known_to_work = 0; 5127 if (!O_CLOEXEC_is_known_to_work) { 5128 int flags = ::fcntl(fd, F_GETFD); 5129 if (flags != -1) { 5130 if ((flags & FD_CLOEXEC) != 0) 5131 O_CLOEXEC_is_known_to_work = 1; 5132 else 5133 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5134 } 5135 } 5136 #endif 5137 5138 return fd; 5139 } 5140 5141 5142 // create binary file, rewriting existing file if required 5143 int os::create_binary_file(const char* path, bool rewrite_existing) { 5144 int oflags = O_WRONLY | O_CREAT; 5145 if (!rewrite_existing) { 5146 oflags |= O_EXCL; 5147 } 5148 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5149 } 5150 5151 // return current position of file pointer 5152 jlong os::current_file_offset(int fd) { 5153 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5154 } 5155 5156 // move file pointer to the specified offset 5157 jlong os::seek_to_file_offset(int fd, jlong offset) { 5158 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5159 } 5160 5161 // This code originates from JDK's sysAvailable 5162 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5163 5164 int os::available(int fd, jlong *bytes) { 5165 jlong cur, end; 5166 int mode; 5167 struct stat64 buf64; 5168 5169 if (::fstat64(fd, &buf64) >= 0) { 5170 mode = buf64.st_mode; 5171 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5172 // XXX: is the following call interruptible? If so, this might 5173 // need to go through the INTERRUPT_IO() wrapper as for other 5174 // blocking, interruptible calls in this file. 5175 int n; 5176 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5177 *bytes = n; 5178 return 1; 5179 } 5180 } 5181 } 5182 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5183 return 0; 5184 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5185 return 0; 5186 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5187 return 0; 5188 } 5189 *bytes = end - cur; 5190 return 1; 5191 } 5192 5193 // Map a block of memory. 5194 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5195 char *addr, size_t bytes, bool read_only, 5196 bool allow_exec) { 5197 int prot; 5198 int flags = MAP_PRIVATE; 5199 5200 if (read_only) { 5201 prot = PROT_READ; 5202 } else { 5203 prot = PROT_READ | PROT_WRITE; 5204 } 5205 5206 if (allow_exec) { 5207 prot |= PROT_EXEC; 5208 } 5209 5210 if (addr != NULL) { 5211 flags |= MAP_FIXED; 5212 } 5213 5214 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5215 fd, file_offset); 5216 if (mapped_address == MAP_FAILED) { 5217 return NULL; 5218 } 5219 return mapped_address; 5220 } 5221 5222 5223 // Remap a block of memory. 5224 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5225 char *addr, size_t bytes, bool read_only, 5226 bool allow_exec) { 5227 // same as map_memory() on this OS 5228 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5229 allow_exec); 5230 } 5231 5232 5233 // Unmap a block of memory. 5234 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5235 return munmap(addr, bytes) == 0; 5236 } 5237 5238 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5239 5240 static clockid_t thread_cpu_clockid(Thread* thread) { 5241 pthread_t tid = thread->osthread()->pthread_id(); 5242 clockid_t clockid; 5243 5244 // Get thread clockid 5245 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5246 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5247 return clockid; 5248 } 5249 5250 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5251 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5252 // of a thread. 5253 // 5254 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5255 // the fast estimate available on the platform. 5256 5257 jlong os::current_thread_cpu_time() { 5258 if (os::Linux::supports_fast_thread_cpu_time()) { 5259 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5260 } else { 5261 // return user + sys since the cost is the same 5262 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5263 } 5264 } 5265 5266 jlong os::thread_cpu_time(Thread* thread) { 5267 // consistent with what current_thread_cpu_time() returns 5268 if (os::Linux::supports_fast_thread_cpu_time()) { 5269 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5270 } else { 5271 return slow_thread_cpu_time(thread, true /* user + sys */); 5272 } 5273 } 5274 5275 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5276 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5277 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5278 } else { 5279 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5280 } 5281 } 5282 5283 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5284 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5285 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5286 } else { 5287 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5288 } 5289 } 5290 5291 // -1 on error. 5292 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5293 pid_t tid = thread->osthread()->thread_id(); 5294 char *s; 5295 char stat[2048]; 5296 int statlen; 5297 char proc_name[64]; 5298 int count; 5299 long sys_time, user_time; 5300 char cdummy; 5301 int idummy; 5302 long ldummy; 5303 FILE *fp; 5304 5305 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid); 5306 fp = fopen(proc_name, "r"); 5307 if (fp == NULL) return -1; 5308 statlen = fread(stat, 1, 2047, fp); 5309 stat[statlen] = '\0'; 5310 fclose(fp); 5311 5312 // Skip pid and the command string. Note that we could be dealing with 5313 // weird command names, e.g. user could decide to rename java launcher 5314 // to "java 1.4.2 :)", then the stat file would look like 5315 // 1234 (java 1.4.2 :)) R ... ... 5316 // We don't really need to know the command string, just find the last 5317 // occurrence of ")" and then start parsing from there. See bug 4726580. 5318 s = strrchr(stat, ')'); 5319 if (s == NULL) return -1; 5320 5321 // Skip blank chars 5322 do { s++; } while (s && isspace(*s)); 5323 5324 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5325 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5326 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5327 &user_time, &sys_time); 5328 if (count != 13) return -1; 5329 if (user_sys_cpu_time) { 5330 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5331 } else { 5332 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5333 } 5334 } 5335 5336 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5337 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5338 info_ptr->may_skip_backward = false; // elapsed time not wall time 5339 info_ptr->may_skip_forward = false; // elapsed time not wall time 5340 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5341 } 5342 5343 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5344 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5345 info_ptr->may_skip_backward = false; // elapsed time not wall time 5346 info_ptr->may_skip_forward = false; // elapsed time not wall time 5347 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5348 } 5349 5350 bool os::is_thread_cpu_time_supported() { 5351 return true; 5352 } 5353 5354 // System loadavg support. Returns -1 if load average cannot be obtained. 5355 // Linux doesn't yet have a (official) notion of processor sets, 5356 // so just return the system wide load average. 5357 int os::loadavg(double loadavg[], int nelem) { 5358 return ::getloadavg(loadavg, nelem); 5359 } 5360 5361 void os::pause() { 5362 char filename[MAX_PATH]; 5363 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5364 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5365 } else { 5366 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5367 } 5368 5369 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5370 if (fd != -1) { 5371 struct stat buf; 5372 ::close(fd); 5373 while (::stat(filename, &buf) == 0) { 5374 (void)::poll(NULL, 0, 100); 5375 } 5376 } else { 5377 jio_fprintf(stderr, 5378 "Could not open pause file '%s', continuing immediately.\n", filename); 5379 } 5380 } 5381 5382 5383 // Refer to the comments in os_solaris.cpp park-unpark. The next two 5384 // comment paragraphs are worth repeating here: 5385 // 5386 // Assumption: 5387 // Only one parker can exist on an event, which is why we allocate 5388 // them per-thread. Multiple unparkers can coexist. 5389 // 5390 // _Event serves as a restricted-range semaphore. 5391 // -1 : thread is blocked, i.e. there is a waiter 5392 // 0 : neutral: thread is running or ready, 5393 // could have been signaled after a wait started 5394 // 1 : signaled - thread is running or ready 5395 // 5396 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5397 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5398 // For specifics regarding the bug see GLIBC BUGID 261237 : 5399 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5400 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5401 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5402 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5403 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5404 // and monitorenter when we're using 1-0 locking. All those operations may result in 5405 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5406 // of libpthread avoids the problem, but isn't practical. 5407 // 5408 // Possible remedies: 5409 // 5410 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5411 // This is palliative and probabilistic, however. If the thread is preempted 5412 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5413 // than the minimum period may have passed, and the abstime may be stale (in the 5414 // past) resultin in a hang. Using this technique reduces the odds of a hang 5415 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5416 // 5417 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5418 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5419 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5420 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5421 // thread. 5422 // 5423 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5424 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5425 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5426 // This also works well. In fact it avoids kernel-level scalability impediments 5427 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5428 // timers in a graceful fashion. 5429 // 5430 // 4. When the abstime value is in the past it appears that control returns 5431 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5432 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5433 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5434 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5435 // It may be possible to avoid reinitialization by checking the return 5436 // value from pthread_cond_timedwait(). In addition to reinitializing the 5437 // condvar we must establish the invariant that cond_signal() is only called 5438 // within critical sections protected by the adjunct mutex. This prevents 5439 // cond_signal() from "seeing" a condvar that's in the midst of being 5440 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5441 // desirable signal-after-unlock optimization that avoids futile context switching. 5442 // 5443 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5444 // structure when a condvar is used or initialized. cond_destroy() would 5445 // release the helper structure. Our reinitialize-after-timedwait fix 5446 // put excessive stress on malloc/free and locks protecting the c-heap. 5447 // 5448 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5449 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5450 // and only enabling the work-around for vulnerable environments. 5451 5452 // utility to compute the abstime argument to timedwait: 5453 // millis is the relative timeout time 5454 // abstime will be the absolute timeout time 5455 // TODO: replace compute_abstime() with unpackTime() 5456 5457 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5458 if (millis < 0) millis = 0; 5459 5460 jlong seconds = millis / 1000; 5461 millis %= 1000; 5462 if (seconds > 50000000) { // see man cond_timedwait(3T) 5463 seconds = 50000000; 5464 } 5465 5466 if (os::supports_monotonic_clock()) { 5467 struct timespec now; 5468 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5469 assert_status(status == 0, status, "clock_gettime"); 5470 abstime->tv_sec = now.tv_sec + seconds; 5471 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5472 if (nanos >= NANOSECS_PER_SEC) { 5473 abstime->tv_sec += 1; 5474 nanos -= NANOSECS_PER_SEC; 5475 } 5476 abstime->tv_nsec = nanos; 5477 } else { 5478 struct timeval now; 5479 int status = gettimeofday(&now, NULL); 5480 assert(status == 0, "gettimeofday"); 5481 abstime->tv_sec = now.tv_sec + seconds; 5482 long usec = now.tv_usec + millis * 1000; 5483 if (usec >= 1000000) { 5484 abstime->tv_sec += 1; 5485 usec -= 1000000; 5486 } 5487 abstime->tv_nsec = usec * 1000; 5488 } 5489 return abstime; 5490 } 5491 5492 void os::PlatformEvent::park() { // AKA "down()" 5493 // Transitions for _Event: 5494 // -1 => -1 : illegal 5495 // 1 => 0 : pass - return immediately 5496 // 0 => -1 : block; then set _Event to 0 before returning 5497 5498 // Invariant: Only the thread associated with the Event/PlatformEvent 5499 // may call park(). 5500 // TODO: assert that _Assoc != NULL or _Assoc == Self 5501 assert(_nParked == 0, "invariant"); 5502 5503 int v; 5504 for (;;) { 5505 v = _Event; 5506 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5507 } 5508 guarantee(v >= 0, "invariant"); 5509 if (v == 0) { 5510 // Do this the hard way by blocking ... 5511 int status = pthread_mutex_lock(_mutex); 5512 assert_status(status == 0, status, "mutex_lock"); 5513 guarantee(_nParked == 0, "invariant"); 5514 ++_nParked; 5515 while (_Event < 0) { 5516 status = pthread_cond_wait(_cond, _mutex); 5517 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5518 // Treat this the same as if the wait was interrupted 5519 if (status == ETIME) { status = EINTR; } 5520 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5521 } 5522 --_nParked; 5523 5524 _Event = 0; 5525 status = pthread_mutex_unlock(_mutex); 5526 assert_status(status == 0, status, "mutex_unlock"); 5527 // Paranoia to ensure our locked and lock-free paths interact 5528 // correctly with each other. 5529 OrderAccess::fence(); 5530 } 5531 guarantee(_Event >= 0, "invariant"); 5532 } 5533 5534 int os::PlatformEvent::park(jlong millis) { 5535 // Transitions for _Event: 5536 // -1 => -1 : illegal 5537 // 1 => 0 : pass - return immediately 5538 // 0 => -1 : block; then set _Event to 0 before returning 5539 5540 guarantee(_nParked == 0, "invariant"); 5541 5542 int v; 5543 for (;;) { 5544 v = _Event; 5545 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5546 } 5547 guarantee(v >= 0, "invariant"); 5548 if (v != 0) return OS_OK; 5549 5550 // We do this the hard way, by blocking the thread. 5551 // Consider enforcing a minimum timeout value. 5552 struct timespec abst; 5553 compute_abstime(&abst, millis); 5554 5555 int ret = OS_TIMEOUT; 5556 int status = pthread_mutex_lock(_mutex); 5557 assert_status(status == 0, status, "mutex_lock"); 5558 guarantee(_nParked == 0, "invariant"); 5559 ++_nParked; 5560 5561 // Object.wait(timo) will return because of 5562 // (a) notification 5563 // (b) timeout 5564 // (c) thread.interrupt 5565 // 5566 // Thread.interrupt and object.notify{All} both call Event::set. 5567 // That is, we treat thread.interrupt as a special case of notification. 5568 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false. 5569 // We assume all ETIME returns are valid. 5570 // 5571 // TODO: properly differentiate simultaneous notify+interrupt. 5572 // In that case, we should propagate the notify to another waiter. 5573 5574 while (_Event < 0) { 5575 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5576 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5577 pthread_cond_destroy(_cond); 5578 pthread_cond_init(_cond, os::Linux::condAttr()); 5579 } 5580 assert_status(status == 0 || status == EINTR || 5581 status == ETIME || status == ETIMEDOUT, 5582 status, "cond_timedwait"); 5583 if (!FilterSpuriousWakeups) break; // previous semantics 5584 if (status == ETIME || status == ETIMEDOUT) break; 5585 // We consume and ignore EINTR and spurious wakeups. 5586 } 5587 --_nParked; 5588 if (_Event >= 0) { 5589 ret = OS_OK; 5590 } 5591 _Event = 0; 5592 status = pthread_mutex_unlock(_mutex); 5593 assert_status(status == 0, status, "mutex_unlock"); 5594 assert(_nParked == 0, "invariant"); 5595 // Paranoia to ensure our locked and lock-free paths interact 5596 // correctly with each other. 5597 OrderAccess::fence(); 5598 return ret; 5599 } 5600 5601 void os::PlatformEvent::unpark() { 5602 // Transitions for _Event: 5603 // 0 => 1 : just return 5604 // 1 => 1 : just return 5605 // -1 => either 0 or 1; must signal target thread 5606 // That is, we can safely transition _Event from -1 to either 5607 // 0 or 1. 5608 // See also: "Semaphores in Plan 9" by Mullender & Cox 5609 // 5610 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5611 // that it will take two back-to-back park() calls for the owning 5612 // thread to block. This has the benefit of forcing a spurious return 5613 // from the first park() call after an unpark() call which will help 5614 // shake out uses of park() and unpark() without condition variables. 5615 5616 if (Atomic::xchg(1, &_Event) >= 0) return; 5617 5618 // Wait for the thread associated with the event to vacate 5619 int status = pthread_mutex_lock(_mutex); 5620 assert_status(status == 0, status, "mutex_lock"); 5621 int AnyWaiters = _nParked; 5622 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5623 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5624 AnyWaiters = 0; 5625 pthread_cond_signal(_cond); 5626 } 5627 status = pthread_mutex_unlock(_mutex); 5628 assert_status(status == 0, status, "mutex_unlock"); 5629 if (AnyWaiters != 0) { 5630 // Note that we signal() *after* dropping the lock for "immortal" Events. 5631 // This is safe and avoids a common class of futile wakeups. In rare 5632 // circumstances this can cause a thread to return prematurely from 5633 // cond_{timed}wait() but the spurious wakeup is benign and the victim 5634 // will simply re-test the condition and re-park itself. 5635 // This provides particular benefit if the underlying platform does not 5636 // provide wait morphing. 5637 status = pthread_cond_signal(_cond); 5638 assert_status(status == 0, status, "cond_signal"); 5639 } 5640 } 5641 5642 5643 // JSR166 5644 // ------------------------------------------------------- 5645 5646 // The solaris and linux implementations of park/unpark are fairly 5647 // conservative for now, but can be improved. They currently use a 5648 // mutex/condvar pair, plus a a count. 5649 // Park decrements count if > 0, else does a condvar wait. Unpark 5650 // sets count to 1 and signals condvar. Only one thread ever waits 5651 // on the condvar. Contention seen when trying to park implies that someone 5652 // is unparking you, so don't wait. And spurious returns are fine, so there 5653 // is no need to track notifications. 5654 5655 // This code is common to linux and solaris and will be moved to a 5656 // common place in dolphin. 5657 // 5658 // The passed in time value is either a relative time in nanoseconds 5659 // or an absolute time in milliseconds. Either way it has to be unpacked 5660 // into suitable seconds and nanoseconds components and stored in the 5661 // given timespec structure. 5662 // Given time is a 64-bit value and the time_t used in the timespec is only 5663 // a signed-32-bit value (except on 64-bit Linux) we have to watch for 5664 // overflow if times way in the future are given. Further on Solaris versions 5665 // prior to 10 there is a restriction (see cond_timedwait) that the specified 5666 // number of seconds, in abstime, is less than current_time + 100,000,000. 5667 // As it will be 28 years before "now + 100000000" will overflow we can 5668 // ignore overflow and just impose a hard-limit on seconds using the value 5669 // of "now + 100,000,000". This places a limit on the timeout of about 3.17 5670 // years from "now". 5671 5672 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5673 assert(time > 0, "convertTime"); 5674 time_t max_secs = 0; 5675 5676 if (!os::supports_monotonic_clock() || isAbsolute) { 5677 struct timeval now; 5678 int status = gettimeofday(&now, NULL); 5679 assert(status == 0, "gettimeofday"); 5680 5681 max_secs = now.tv_sec + MAX_SECS; 5682 5683 if (isAbsolute) { 5684 jlong secs = time / 1000; 5685 if (secs > max_secs) { 5686 absTime->tv_sec = max_secs; 5687 } else { 5688 absTime->tv_sec = secs; 5689 } 5690 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5691 } else { 5692 jlong secs = time / NANOSECS_PER_SEC; 5693 if (secs >= MAX_SECS) { 5694 absTime->tv_sec = max_secs; 5695 absTime->tv_nsec = 0; 5696 } else { 5697 absTime->tv_sec = now.tv_sec + secs; 5698 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5699 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5700 absTime->tv_nsec -= NANOSECS_PER_SEC; 5701 ++absTime->tv_sec; // note: this must be <= max_secs 5702 } 5703 } 5704 } 5705 } else { 5706 // must be relative using monotonic clock 5707 struct timespec now; 5708 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5709 assert_status(status == 0, status, "clock_gettime"); 5710 max_secs = now.tv_sec + MAX_SECS; 5711 jlong secs = time / NANOSECS_PER_SEC; 5712 if (secs >= MAX_SECS) { 5713 absTime->tv_sec = max_secs; 5714 absTime->tv_nsec = 0; 5715 } else { 5716 absTime->tv_sec = now.tv_sec + secs; 5717 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5718 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5719 absTime->tv_nsec -= NANOSECS_PER_SEC; 5720 ++absTime->tv_sec; // note: this must be <= max_secs 5721 } 5722 } 5723 } 5724 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5725 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5726 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5727 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5728 } 5729 5730 void Parker::park(bool isAbsolute, jlong time) { 5731 // Ideally we'd do something useful while spinning, such 5732 // as calling unpackTime(). 5733 5734 // Optional fast-path check: 5735 // Return immediately if a permit is available. 5736 // We depend on Atomic::xchg() having full barrier semantics 5737 // since we are doing a lock-free update to _counter. 5738 if (Atomic::xchg(0, &_counter) > 0) return; 5739 5740 Thread* thread = Thread::current(); 5741 assert(thread->is_Java_thread(), "Must be JavaThread"); 5742 JavaThread *jt = (JavaThread *)thread; 5743 5744 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5745 // Check interrupt before trying to wait 5746 if (Thread::is_interrupted(thread, false)) { 5747 return; 5748 } 5749 5750 // Next, demultiplex/decode time arguments 5751 timespec absTime; 5752 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all 5753 return; 5754 } 5755 if (time > 0) { 5756 unpackTime(&absTime, isAbsolute, time); 5757 } 5758 5759 5760 // Enter safepoint region 5761 // Beware of deadlocks such as 6317397. 5762 // The per-thread Parker:: mutex is a classic leaf-lock. 5763 // In particular a thread must never block on the Threads_lock while 5764 // holding the Parker:: mutex. If safepoints are pending both the 5765 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5766 ThreadBlockInVM tbivm(jt); 5767 5768 // Don't wait if cannot get lock since interference arises from 5769 // unblocking. Also. check interrupt before trying wait 5770 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5771 return; 5772 } 5773 5774 int status; 5775 if (_counter > 0) { // no wait needed 5776 _counter = 0; 5777 status = pthread_mutex_unlock(_mutex); 5778 assert(status == 0, "invariant"); 5779 // Paranoia to ensure our locked and lock-free paths interact 5780 // correctly with each other and Java-level accesses. 5781 OrderAccess::fence(); 5782 return; 5783 } 5784 5785 #ifdef ASSERT 5786 // Don't catch signals while blocked; let the running threads have the signals. 5787 // (This allows a debugger to break into the running thread.) 5788 sigset_t oldsigs; 5789 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5790 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5791 #endif 5792 5793 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5794 jt->set_suspend_equivalent(); 5795 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5796 5797 assert(_cur_index == -1, "invariant"); 5798 if (time == 0) { 5799 _cur_index = REL_INDEX; // arbitrary choice when not timed 5800 status = pthread_cond_wait(&_cond[_cur_index], _mutex); 5801 } else { 5802 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5803 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime); 5804 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5805 pthread_cond_destroy(&_cond[_cur_index]); 5806 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5807 } 5808 } 5809 _cur_index = -1; 5810 assert_status(status == 0 || status == EINTR || 5811 status == ETIME || status == ETIMEDOUT, 5812 status, "cond_timedwait"); 5813 5814 #ifdef ASSERT 5815 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5816 #endif 5817 5818 _counter = 0; 5819 status = pthread_mutex_unlock(_mutex); 5820 assert_status(status == 0, status, "invariant"); 5821 // Paranoia to ensure our locked and lock-free paths interact 5822 // correctly with each other and Java-level accesses. 5823 OrderAccess::fence(); 5824 5825 // If externally suspended while waiting, re-suspend 5826 if (jt->handle_special_suspend_equivalent_condition()) { 5827 jt->java_suspend_self(); 5828 } 5829 } 5830 5831 void Parker::unpark() { 5832 int status = pthread_mutex_lock(_mutex); 5833 assert(status == 0, "invariant"); 5834 const int s = _counter; 5835 _counter = 1; 5836 if (s < 1) { 5837 // thread might be parked 5838 if (_cur_index != -1) { 5839 // thread is definitely parked 5840 if (WorkAroundNPTLTimedWaitHang) { 5841 status = pthread_cond_signal(&_cond[_cur_index]); 5842 assert(status == 0, "invariant"); 5843 status = pthread_mutex_unlock(_mutex); 5844 assert(status == 0, "invariant"); 5845 } else { 5846 status = pthread_mutex_unlock(_mutex); 5847 assert(status == 0, "invariant"); 5848 status = pthread_cond_signal(&_cond[_cur_index]); 5849 assert(status == 0, "invariant"); 5850 } 5851 } else { 5852 pthread_mutex_unlock(_mutex); 5853 assert(status == 0, "invariant"); 5854 } 5855 } else { 5856 pthread_mutex_unlock(_mutex); 5857 assert(status == 0, "invariant"); 5858 } 5859 } 5860 5861 5862 extern char** environ; 5863 5864 #ifndef __NR_fork 5865 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5866 #endif 5867 5868 #ifndef __NR_execve 5869 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 5870 #endif 5871 5872 // Run the specified command in a separate process. Return its exit value, 5873 // or -1 on failure (e.g. can't fork a new process). 5874 // Unlike system(), this function can be called from signal handler. It 5875 // doesn't block SIGINT et al. 5876 int os::fork_and_exec(char* cmd) { 5877 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5878 5879 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5880 // pthread_atfork handlers and reset pthread library. All we need is a 5881 // separate process to execve. Make a direct syscall to fork process. 5882 // On IA64 there's no fork syscall, we have to use fork() and hope for 5883 // the best... 5884 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5885 IA64_ONLY(fork();) 5886 5887 if (pid < 0) { 5888 // fork failed 5889 return -1; 5890 5891 } else if (pid == 0) { 5892 // child process 5893 5894 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5895 // first to kill every thread on the thread list. Because this list is 5896 // not reset by fork() (see notes above), execve() will instead kill 5897 // every thread in the parent process. We know this is the only thread 5898 // in the new process, so make a system call directly. 5899 // IA64 should use normal execve() from glibc to match the glibc fork() 5900 // above. 5901 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5902 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5903 5904 // execve failed 5905 _exit(-1); 5906 5907 } else { 5908 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5909 // care about the actual exit code, for now. 5910 5911 int status; 5912 5913 // Wait for the child process to exit. This returns immediately if 5914 // the child has already exited. */ 5915 while (waitpid(pid, &status, 0) < 0) { 5916 switch (errno) { 5917 case ECHILD: return 0; 5918 case EINTR: break; 5919 default: return -1; 5920 } 5921 } 5922 5923 if (WIFEXITED(status)) { 5924 // The child exited normally; get its exit code. 5925 return WEXITSTATUS(status); 5926 } else if (WIFSIGNALED(status)) { 5927 // The child exited because of a signal 5928 // The best value to return is 0x80 + signal number, 5929 // because that is what all Unix shells do, and because 5930 // it allows callers to distinguish between process exit and 5931 // process death by signal. 5932 return 0x80 + WTERMSIG(status); 5933 } else { 5934 // Unknown exit code; pass it through 5935 return status; 5936 } 5937 } 5938 } 5939 5940 // is_headless_jre() 5941 // 5942 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 5943 // in order to report if we are running in a headless jre 5944 // 5945 // Since JDK8 xawt/libmawt.so was moved into the same directory 5946 // as libawt.so, and renamed libawt_xawt.so 5947 // 5948 bool os::is_headless_jre() { 5949 struct stat statbuf; 5950 char buf[MAXPATHLEN]; 5951 char libmawtpath[MAXPATHLEN]; 5952 const char *xawtstr = "/xawt/libmawt.so"; 5953 const char *new_xawtstr = "/libawt_xawt.so"; 5954 char *p; 5955 5956 // Get path to libjvm.so 5957 os::jvm_path(buf, sizeof(buf)); 5958 5959 // Get rid of libjvm.so 5960 p = strrchr(buf, '/'); 5961 if (p == NULL) { 5962 return false; 5963 } else { 5964 *p = '\0'; 5965 } 5966 5967 // Get rid of client or server 5968 p = strrchr(buf, '/'); 5969 if (p == NULL) { 5970 return false; 5971 } else { 5972 *p = '\0'; 5973 } 5974 5975 // check xawt/libmawt.so 5976 strcpy(libmawtpath, buf); 5977 strcat(libmawtpath, xawtstr); 5978 if (::stat(libmawtpath, &statbuf) == 0) return false; 5979 5980 // check libawt_xawt.so 5981 strcpy(libmawtpath, buf); 5982 strcat(libmawtpath, new_xawtstr); 5983 if (::stat(libmawtpath, &statbuf) == 0) return false; 5984 5985 return true; 5986 } 5987 5988 // Get the default path to the core file 5989 // Returns the length of the string 5990 int os::get_core_path(char* buffer, size_t bufferSize) { 5991 const char* p = get_current_directory(buffer, bufferSize); 5992 5993 if (p == NULL) { 5994 assert(p != NULL, "failed to get current directory"); 5995 return 0; 5996 } 5997 5998 return strlen(buffer); 5999 } 6000 6001 /////////////// Unit tests /////////////// 6002 6003 #ifndef PRODUCT 6004 6005 #define test_log(...) \ 6006 do { \ 6007 if (VerboseInternalVMTests) { \ 6008 tty->print_cr(__VA_ARGS__); \ 6009 tty->flush(); \ 6010 } \ 6011 } while (false) 6012 6013 class TestReserveMemorySpecial : AllStatic { 6014 public: 6015 static void small_page_write(void* addr, size_t size) { 6016 size_t page_size = os::vm_page_size(); 6017 6018 char* end = (char*)addr + size; 6019 for (char* p = (char*)addr; p < end; p += page_size) { 6020 *p = 1; 6021 } 6022 } 6023 6024 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6025 if (!UseHugeTLBFS) { 6026 return; 6027 } 6028 6029 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6030 6031 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6032 6033 if (addr != NULL) { 6034 small_page_write(addr, size); 6035 6036 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6037 } 6038 } 6039 6040 static void test_reserve_memory_special_huge_tlbfs_only() { 6041 if (!UseHugeTLBFS) { 6042 return; 6043 } 6044 6045 size_t lp = os::large_page_size(); 6046 6047 for (size_t size = lp; size <= lp * 10; size += lp) { 6048 test_reserve_memory_special_huge_tlbfs_only(size); 6049 } 6050 } 6051 6052 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) { 6053 if (!UseHugeTLBFS) { 6054 return; 6055 } 6056 6057 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")", 6058 size, alignment); 6059 6060 assert(size >= os::large_page_size(), "Incorrect input to test"); 6061 6062 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6063 6064 if (addr != NULL) { 6065 small_page_write(addr, size); 6066 6067 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6068 } 6069 } 6070 6071 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) { 6072 size_t lp = os::large_page_size(); 6073 size_t ag = os::vm_allocation_granularity(); 6074 6075 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6076 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment); 6077 } 6078 } 6079 6080 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6081 size_t lp = os::large_page_size(); 6082 size_t ag = os::vm_allocation_granularity(); 6083 6084 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp); 6085 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag); 6086 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2); 6087 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2); 6088 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag); 6089 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag); 6090 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2); 6091 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10); 6092 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2); 6093 } 6094 6095 static void test_reserve_memory_special_huge_tlbfs() { 6096 if (!UseHugeTLBFS) { 6097 return; 6098 } 6099 6100 test_reserve_memory_special_huge_tlbfs_only(); 6101 test_reserve_memory_special_huge_tlbfs_mixed(); 6102 } 6103 6104 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6105 if (!UseSHM) { 6106 return; 6107 } 6108 6109 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6110 6111 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6112 6113 if (addr != NULL) { 6114 assert(is_ptr_aligned(addr, alignment), "Check"); 6115 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6116 6117 small_page_write(addr, size); 6118 6119 os::Linux::release_memory_special_shm(addr, size); 6120 } 6121 } 6122 6123 static void test_reserve_memory_special_shm() { 6124 size_t lp = os::large_page_size(); 6125 size_t ag = os::vm_allocation_granularity(); 6126 6127 for (size_t size = ag; size < lp * 3; size += ag) { 6128 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6129 test_reserve_memory_special_shm(size, alignment); 6130 } 6131 } 6132 } 6133 6134 static void test() { 6135 test_reserve_memory_special_huge_tlbfs(); 6136 test_reserve_memory_special_shm(); 6137 } 6138 }; 6139 6140 void TestReserveMemorySpecial_test() { 6141 TestReserveMemorySpecial::test(); 6142 } 6143 6144 #endif