1 /* 2 * Copyright (c) 1999, 2015, 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 void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) { 1326 timeval time; 1327 int status = gettimeofday(&time, NULL); 1328 assert(status != -1, "linux error"); 1329 seconds = jlong(time.tv_sec); 1330 nanos = jlong(time.tv_usec) * 1000; 1331 } 1332 1333 1334 #ifndef CLOCK_MONOTONIC 1335 #define CLOCK_MONOTONIC (1) 1336 #endif 1337 1338 void os::Linux::clock_init() { 1339 // we do dlopen's in this particular order due to bug in linux 1340 // dynamical loader (see 6348968) leading to crash on exit 1341 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1342 if (handle == NULL) { 1343 handle = dlopen("librt.so", RTLD_LAZY); 1344 } 1345 1346 if (handle) { 1347 int (*clock_getres_func)(clockid_t, struct timespec*) = 1348 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1349 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1350 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1351 if (clock_getres_func && clock_gettime_func) { 1352 // See if monotonic clock is supported by the kernel. Note that some 1353 // early implementations simply return kernel jiffies (updated every 1354 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1355 // for nano time (though the monotonic property is still nice to have). 1356 // It's fixed in newer kernels, however clock_getres() still returns 1357 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1358 // resolution for now. Hopefully as people move to new kernels, this 1359 // won't be a problem. 1360 struct timespec res; 1361 struct timespec tp; 1362 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1363 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1364 // yes, monotonic clock is supported 1365 _clock_gettime = clock_gettime_func; 1366 return; 1367 } else { 1368 // close librt if there is no monotonic clock 1369 dlclose(handle); 1370 } 1371 } 1372 } 1373 warning("No monotonic clock was available - timed services may " \ 1374 "be adversely affected if the time-of-day clock changes"); 1375 } 1376 1377 #ifndef SYS_clock_getres 1378 #if defined(IA32) || defined(AMD64) 1379 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1380 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1381 #else 1382 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1383 #define sys_clock_getres(x,y) -1 1384 #endif 1385 #else 1386 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1387 #endif 1388 1389 void os::Linux::fast_thread_clock_init() { 1390 if (!UseLinuxPosixThreadCPUClocks) { 1391 return; 1392 } 1393 clockid_t clockid; 1394 struct timespec tp; 1395 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1396 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1397 1398 // Switch to using fast clocks for thread cpu time if 1399 // the sys_clock_getres() returns 0 error code. 1400 // Note, that some kernels may support the current thread 1401 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1402 // returned by the pthread_getcpuclockid(). 1403 // If the fast Posix clocks are supported then the sys_clock_getres() 1404 // must return at least tp.tv_sec == 0 which means a resolution 1405 // better than 1 sec. This is extra check for reliability. 1406 1407 if (pthread_getcpuclockid_func && 1408 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1409 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1410 _supports_fast_thread_cpu_time = true; 1411 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1412 } 1413 } 1414 1415 jlong os::javaTimeNanos() { 1416 if (os::supports_monotonic_clock()) { 1417 struct timespec tp; 1418 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1419 assert(status == 0, "gettime error"); 1420 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1421 return result; 1422 } else { 1423 timeval time; 1424 int status = gettimeofday(&time, NULL); 1425 assert(status != -1, "linux error"); 1426 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1427 return 1000 * usecs; 1428 } 1429 } 1430 1431 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1432 if (os::supports_monotonic_clock()) { 1433 info_ptr->max_value = ALL_64_BITS; 1434 1435 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1436 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1437 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1438 } else { 1439 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1440 info_ptr->max_value = ALL_64_BITS; 1441 1442 // gettimeofday is a real time clock so it skips 1443 info_ptr->may_skip_backward = true; 1444 info_ptr->may_skip_forward = true; 1445 } 1446 1447 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1448 } 1449 1450 // Return the real, user, and system times in seconds from an 1451 // arbitrary fixed point in the past. 1452 bool os::getTimesSecs(double* process_real_time, 1453 double* process_user_time, 1454 double* process_system_time) { 1455 struct tms ticks; 1456 clock_t real_ticks = times(&ticks); 1457 1458 if (real_ticks == (clock_t) (-1)) { 1459 return false; 1460 } else { 1461 double ticks_per_second = (double) clock_tics_per_sec; 1462 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1463 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1464 *process_real_time = ((double) real_ticks) / ticks_per_second; 1465 1466 return true; 1467 } 1468 } 1469 1470 1471 char * os::local_time_string(char *buf, size_t buflen) { 1472 struct tm t; 1473 time_t long_time; 1474 time(&long_time); 1475 localtime_r(&long_time, &t); 1476 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1477 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1478 t.tm_hour, t.tm_min, t.tm_sec); 1479 return buf; 1480 } 1481 1482 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1483 return localtime_r(clock, res); 1484 } 1485 1486 //////////////////////////////////////////////////////////////////////////////// 1487 // runtime exit support 1488 1489 // Note: os::shutdown() might be called very early during initialization, or 1490 // called from signal handler. Before adding something to os::shutdown(), make 1491 // sure it is async-safe and can handle partially initialized VM. 1492 void os::shutdown() { 1493 1494 // allow PerfMemory to attempt cleanup of any persistent resources 1495 perfMemory_exit(); 1496 1497 // needs to remove object in file system 1498 AttachListener::abort(); 1499 1500 // flush buffered output, finish log files 1501 ostream_abort(); 1502 1503 // Check for abort hook 1504 abort_hook_t abort_hook = Arguments::abort_hook(); 1505 if (abort_hook != NULL) { 1506 abort_hook(); 1507 } 1508 1509 } 1510 1511 // Note: os::abort() might be called very early during initialization, or 1512 // called from signal handler. Before adding something to os::abort(), make 1513 // sure it is async-safe and can handle partially initialized VM. 1514 void os::abort(bool dump_core) { 1515 os::shutdown(); 1516 if (dump_core) { 1517 #ifndef PRODUCT 1518 fdStream out(defaultStream::output_fd()); 1519 out.print_raw("Current thread is "); 1520 char buf[16]; 1521 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1522 out.print_raw_cr(buf); 1523 out.print_raw_cr("Dumping core ..."); 1524 #endif 1525 ::abort(); // dump core 1526 } 1527 1528 ::exit(1); 1529 } 1530 1531 // Die immediately, no exit hook, no abort hook, no cleanup. 1532 void os::die() { 1533 // _exit() on LinuxThreads only kills current thread 1534 ::abort(); 1535 } 1536 1537 1538 // This method is a copy of JDK's sysGetLastErrorString 1539 // from src/solaris/hpi/src/system_md.c 1540 1541 size_t os::lasterror(char *buf, size_t len) { 1542 if (errno == 0) return 0; 1543 1544 const char *s = ::strerror(errno); 1545 size_t n = ::strlen(s); 1546 if (n >= len) { 1547 n = len - 1; 1548 } 1549 ::strncpy(buf, s, n); 1550 buf[n] = '\0'; 1551 return n; 1552 } 1553 1554 intx os::current_thread_id() { return (intx)pthread_self(); } 1555 int os::current_process_id() { 1556 1557 // Under the old linux thread library, linux gives each thread 1558 // its own process id. Because of this each thread will return 1559 // a different pid if this method were to return the result 1560 // of getpid(2). Linux provides no api that returns the pid 1561 // of the launcher thread for the vm. This implementation 1562 // returns a unique pid, the pid of the launcher thread 1563 // that starts the vm 'process'. 1564 1565 // Under the NPTL, getpid() returns the same pid as the 1566 // launcher thread rather than a unique pid per thread. 1567 // Use gettid() if you want the old pre NPTL behaviour. 1568 1569 // if you are looking for the result of a call to getpid() that 1570 // returns a unique pid for the calling thread, then look at the 1571 // OSThread::thread_id() method in osThread_linux.hpp file 1572 1573 return (int)(_initial_pid ? _initial_pid : getpid()); 1574 } 1575 1576 // DLL functions 1577 1578 const char* os::dll_file_extension() { return ".so"; } 1579 1580 // This must be hard coded because it's the system's temporary 1581 // directory not the java application's temp directory, ala java.io.tmpdir. 1582 const char* os::get_temp_directory() { return "/tmp"; } 1583 1584 static bool file_exists(const char* filename) { 1585 struct stat statbuf; 1586 if (filename == NULL || strlen(filename) == 0) { 1587 return false; 1588 } 1589 return os::stat(filename, &statbuf) == 0; 1590 } 1591 1592 bool os::dll_build_name(char* buffer, size_t buflen, 1593 const char* pname, const char* fname) { 1594 bool retval = false; 1595 // Copied from libhpi 1596 const size_t pnamelen = pname ? strlen(pname) : 0; 1597 1598 // Return error on buffer overflow. 1599 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1600 return retval; 1601 } 1602 1603 if (pnamelen == 0) { 1604 snprintf(buffer, buflen, "lib%s.so", fname); 1605 retval = true; 1606 } else if (strchr(pname, *os::path_separator()) != NULL) { 1607 int n; 1608 char** pelements = split_path(pname, &n); 1609 if (pelements == NULL) { 1610 return false; 1611 } 1612 for (int i = 0; i < n; i++) { 1613 // Really shouldn't be NULL, but check can't hurt 1614 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1615 continue; // skip the empty path values 1616 } 1617 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1618 if (file_exists(buffer)) { 1619 retval = true; 1620 break; 1621 } 1622 } 1623 // release the storage 1624 for (int i = 0; i < n; i++) { 1625 if (pelements[i] != NULL) { 1626 FREE_C_HEAP_ARRAY(char, pelements[i]); 1627 } 1628 } 1629 if (pelements != NULL) { 1630 FREE_C_HEAP_ARRAY(char*, pelements); 1631 } 1632 } else { 1633 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1634 retval = true; 1635 } 1636 return retval; 1637 } 1638 1639 // check if addr is inside libjvm.so 1640 bool os::address_is_in_vm(address addr) { 1641 static address libjvm_base_addr; 1642 Dl_info dlinfo; 1643 1644 if (libjvm_base_addr == NULL) { 1645 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1646 libjvm_base_addr = (address)dlinfo.dli_fbase; 1647 } 1648 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1649 } 1650 1651 if (dladdr((void *)addr, &dlinfo) != 0) { 1652 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1653 } 1654 1655 return false; 1656 } 1657 1658 bool os::dll_address_to_function_name(address addr, char *buf, 1659 int buflen, int *offset) { 1660 // buf is not optional, but offset is optional 1661 assert(buf != NULL, "sanity check"); 1662 1663 Dl_info dlinfo; 1664 1665 if (dladdr((void*)addr, &dlinfo) != 0) { 1666 // see if we have a matching symbol 1667 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1668 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1669 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1670 } 1671 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1672 return true; 1673 } 1674 // no matching symbol so try for just file info 1675 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1676 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1677 buf, buflen, offset, dlinfo.dli_fname)) { 1678 return true; 1679 } 1680 } 1681 } 1682 1683 buf[0] = '\0'; 1684 if (offset != NULL) *offset = -1; 1685 return false; 1686 } 1687 1688 struct _address_to_library_name { 1689 address addr; // input : memory address 1690 size_t buflen; // size of fname 1691 char* fname; // output: library name 1692 address base; // library base addr 1693 }; 1694 1695 static int address_to_library_name_callback(struct dl_phdr_info *info, 1696 size_t size, void *data) { 1697 int i; 1698 bool found = false; 1699 address libbase = NULL; 1700 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1701 1702 // iterate through all loadable segments 1703 for (i = 0; i < info->dlpi_phnum; i++) { 1704 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1705 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1706 // base address of a library is the lowest address of its loaded 1707 // segments. 1708 if (libbase == NULL || libbase > segbase) { 1709 libbase = segbase; 1710 } 1711 // see if 'addr' is within current segment 1712 if (segbase <= d->addr && 1713 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1714 found = true; 1715 } 1716 } 1717 } 1718 1719 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1720 // so dll_address_to_library_name() can fall through to use dladdr() which 1721 // can figure out executable name from argv[0]. 1722 if (found && info->dlpi_name && info->dlpi_name[0]) { 1723 d->base = libbase; 1724 if (d->fname) { 1725 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1726 } 1727 return 1; 1728 } 1729 return 0; 1730 } 1731 1732 bool os::dll_address_to_library_name(address addr, char* buf, 1733 int buflen, int* offset) { 1734 // buf is not optional, but offset is optional 1735 assert(buf != NULL, "sanity check"); 1736 1737 Dl_info dlinfo; 1738 struct _address_to_library_name data; 1739 1740 // There is a bug in old glibc dladdr() implementation that it could resolve 1741 // to wrong library name if the .so file has a base address != NULL. Here 1742 // we iterate through the program headers of all loaded libraries to find 1743 // out which library 'addr' really belongs to. This workaround can be 1744 // removed once the minimum requirement for glibc is moved to 2.3.x. 1745 data.addr = addr; 1746 data.fname = buf; 1747 data.buflen = buflen; 1748 data.base = NULL; 1749 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1750 1751 if (rslt) { 1752 // buf already contains library name 1753 if (offset) *offset = addr - data.base; 1754 return true; 1755 } 1756 if (dladdr((void*)addr, &dlinfo) != 0) { 1757 if (dlinfo.dli_fname != NULL) { 1758 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1759 } 1760 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1761 *offset = addr - (address)dlinfo.dli_fbase; 1762 } 1763 return true; 1764 } 1765 1766 buf[0] = '\0'; 1767 if (offset) *offset = -1; 1768 return false; 1769 } 1770 1771 // Loads .dll/.so and 1772 // in case of error it checks if .dll/.so was built for the 1773 // same architecture as Hotspot is running on 1774 1775 1776 // Remember the stack's state. The Linux dynamic linker will change 1777 // the stack to 'executable' at most once, so we must safepoint only once. 1778 bool os::Linux::_stack_is_executable = false; 1779 1780 // VM operation that loads a library. This is necessary if stack protection 1781 // of the Java stacks can be lost during loading the library. If we 1782 // do not stop the Java threads, they can stack overflow before the stacks 1783 // are protected again. 1784 class VM_LinuxDllLoad: public VM_Operation { 1785 private: 1786 const char *_filename; 1787 char *_ebuf; 1788 int _ebuflen; 1789 void *_lib; 1790 public: 1791 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1792 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1793 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1794 void doit() { 1795 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1796 os::Linux::_stack_is_executable = true; 1797 } 1798 void* loaded_library() { return _lib; } 1799 }; 1800 1801 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) { 1802 void * result = NULL; 1803 bool load_attempted = false; 1804 1805 // Check whether the library to load might change execution rights 1806 // of the stack. If they are changed, the protection of the stack 1807 // guard pages will be lost. We need a safepoint to fix this. 1808 // 1809 // See Linux man page execstack(8) for more info. 1810 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1811 ElfFile ef(filename); 1812 if (!ef.specifies_noexecstack()) { 1813 if (!is_init_completed()) { 1814 os::Linux::_stack_is_executable = true; 1815 // This is OK - No Java threads have been created yet, and hence no 1816 // stack guard pages to fix. 1817 // 1818 // This should happen only when you are building JDK7 using a very 1819 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1820 // 1821 // Dynamic loader will make all stacks executable after 1822 // this function returns, and will not do that again. 1823 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1824 } else { 1825 warning("You have loaded library %s which might have disabled stack guard. " 1826 "The VM will try to fix the stack guard now.\n" 1827 "It's highly recommended that you fix the library with " 1828 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1829 filename); 1830 1831 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1832 JavaThread *jt = JavaThread::current(); 1833 if (jt->thread_state() != _thread_in_native) { 1834 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1835 // that requires ExecStack. Cannot enter safe point. Let's give up. 1836 warning("Unable to fix stack guard. Giving up."); 1837 } else { 1838 if (!LoadExecStackDllInVMThread) { 1839 // This is for the case where the DLL has an static 1840 // constructor function that executes JNI code. We cannot 1841 // load such DLLs in the VMThread. 1842 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1843 } 1844 1845 ThreadInVMfromNative tiv(jt); 1846 debug_only(VMNativeEntryWrapper vew;) 1847 1848 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1849 VMThread::execute(&op); 1850 if (LoadExecStackDllInVMThread) { 1851 result = op.loaded_library(); 1852 } 1853 load_attempted = true; 1854 } 1855 } 1856 } 1857 } 1858 1859 if (!load_attempted) { 1860 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1861 } 1862 1863 if (result != NULL) { 1864 // Successful loading 1865 return result; 1866 } 1867 1868 Elf32_Ehdr elf_head; 1869 int diag_msg_max_length=ebuflen-strlen(ebuf); 1870 char* diag_msg_buf=ebuf+strlen(ebuf); 1871 1872 if (diag_msg_max_length==0) { 1873 // No more space in ebuf for additional diagnostics message 1874 return NULL; 1875 } 1876 1877 1878 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1879 1880 if (file_descriptor < 0) { 1881 // Can't open library, report dlerror() message 1882 return NULL; 1883 } 1884 1885 bool failed_to_read_elf_head= 1886 (sizeof(elf_head)!= 1887 (::read(file_descriptor, &elf_head,sizeof(elf_head)))); 1888 1889 ::close(file_descriptor); 1890 if (failed_to_read_elf_head) { 1891 // file i/o error - report dlerror() msg 1892 return NULL; 1893 } 1894 1895 typedef struct { 1896 Elf32_Half code; // Actual value as defined in elf.h 1897 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1898 char elf_class; // 32 or 64 bit 1899 char endianess; // MSB or LSB 1900 char* name; // String representation 1901 } arch_t; 1902 1903 #ifndef EM_486 1904 #define EM_486 6 /* Intel 80486 */ 1905 #endif 1906 1907 static const arch_t arch_array[]={ 1908 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1909 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1910 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1911 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1912 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1913 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1914 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1915 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1916 #if defined(VM_LITTLE_ENDIAN) 1917 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"}, 1918 #else 1919 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1920 #endif 1921 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1922 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1923 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1924 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1925 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1926 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1927 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1928 }; 1929 1930 #if (defined IA32) 1931 static Elf32_Half running_arch_code=EM_386; 1932 #elif (defined AMD64) 1933 static Elf32_Half running_arch_code=EM_X86_64; 1934 #elif (defined IA64) 1935 static Elf32_Half running_arch_code=EM_IA_64; 1936 #elif (defined __sparc) && (defined _LP64) 1937 static Elf32_Half running_arch_code=EM_SPARCV9; 1938 #elif (defined __sparc) && (!defined _LP64) 1939 static Elf32_Half running_arch_code=EM_SPARC; 1940 #elif (defined __powerpc64__) 1941 static Elf32_Half running_arch_code=EM_PPC64; 1942 #elif (defined __powerpc__) 1943 static Elf32_Half running_arch_code=EM_PPC; 1944 #elif (defined ARM) 1945 static Elf32_Half running_arch_code=EM_ARM; 1946 #elif (defined S390) 1947 static Elf32_Half running_arch_code=EM_S390; 1948 #elif (defined ALPHA) 1949 static Elf32_Half running_arch_code=EM_ALPHA; 1950 #elif (defined MIPSEL) 1951 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1952 #elif (defined PARISC) 1953 static Elf32_Half running_arch_code=EM_PARISC; 1954 #elif (defined MIPS) 1955 static Elf32_Half running_arch_code=EM_MIPS; 1956 #elif (defined M68K) 1957 static Elf32_Half running_arch_code=EM_68K; 1958 #else 1959 #error Method os::dll_load requires that one of following is defined:\ 1960 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1961 #endif 1962 1963 // Identify compatability class for VM's architecture and library's architecture 1964 // Obtain string descriptions for architectures 1965 1966 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1967 int running_arch_index=-1; 1968 1969 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) { 1970 if (running_arch_code == arch_array[i].code) { 1971 running_arch_index = i; 1972 } 1973 if (lib_arch.code == arch_array[i].code) { 1974 lib_arch.compat_class = arch_array[i].compat_class; 1975 lib_arch.name = arch_array[i].name; 1976 } 1977 } 1978 1979 assert(running_arch_index != -1, 1980 "Didn't find running architecture code (running_arch_code) in arch_array"); 1981 if (running_arch_index == -1) { 1982 // Even though running architecture detection failed 1983 // we may still continue with reporting dlerror() message 1984 return NULL; 1985 } 1986 1987 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1988 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1989 return NULL; 1990 } 1991 1992 #ifndef S390 1993 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 1994 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 1995 return NULL; 1996 } 1997 #endif // !S390 1998 1999 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 2000 if (lib_arch.name!=NULL) { 2001 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2002 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 2003 lib_arch.name, arch_array[running_arch_index].name); 2004 } else { 2005 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2006 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 2007 lib_arch.code, 2008 arch_array[running_arch_index].name); 2009 } 2010 } 2011 2012 return NULL; 2013 } 2014 2015 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, 2016 int ebuflen) { 2017 void * result = ::dlopen(filename, RTLD_LAZY); 2018 if (result == NULL) { 2019 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2020 ebuf[ebuflen-1] = '\0'; 2021 } 2022 return result; 2023 } 2024 2025 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, 2026 int ebuflen) { 2027 void * result = NULL; 2028 if (LoadExecStackDllInVMThread) { 2029 result = dlopen_helper(filename, ebuf, ebuflen); 2030 } 2031 2032 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2033 // library that requires an executable stack, or which does not have this 2034 // stack attribute set, dlopen changes the stack attribute to executable. The 2035 // read protection of the guard pages gets lost. 2036 // 2037 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2038 // may have been queued at the same time. 2039 2040 if (!_stack_is_executable) { 2041 JavaThread *jt = Threads::first(); 2042 2043 while (jt) { 2044 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2045 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2046 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2047 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2048 warning("Attempt to reguard stack yellow zone failed."); 2049 } 2050 } 2051 jt = jt->next(); 2052 } 2053 } 2054 2055 return result; 2056 } 2057 2058 // glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2059 // chances are you might want to run the generated bits against glibc-2.0 2060 // libdl.so, so always use locking for any version of glibc. 2061 // 2062 void* os::dll_lookup(void* handle, const char* name) { 2063 pthread_mutex_lock(&dl_mutex); 2064 void* res = dlsym(handle, name); 2065 pthread_mutex_unlock(&dl_mutex); 2066 return res; 2067 } 2068 2069 void* os::get_default_process_handle() { 2070 return (void*)::dlopen(NULL, RTLD_LAZY); 2071 } 2072 2073 static bool _print_ascii_file(const char* filename, outputStream* st) { 2074 int fd = ::open(filename, O_RDONLY); 2075 if (fd == -1) { 2076 return false; 2077 } 2078 2079 char buf[32]; 2080 int bytes; 2081 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2082 st->print_raw(buf, bytes); 2083 } 2084 2085 ::close(fd); 2086 2087 return true; 2088 } 2089 2090 void os::print_dll_info(outputStream *st) { 2091 st->print_cr("Dynamic libraries:"); 2092 2093 char fname[32]; 2094 pid_t pid = os::Linux::gettid(); 2095 2096 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2097 2098 if (!_print_ascii_file(fname, st)) { 2099 st->print("Can not get library information for pid = %d\n", pid); 2100 } 2101 } 2102 2103 int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) { 2104 FILE *procmapsFile = NULL; 2105 2106 // Open the procfs maps file for the current process 2107 if ((procmapsFile = fopen("/proc/self/maps", "r")) != NULL) { 2108 // Allocate PATH_MAX for file name plus a reasonable size for other fields. 2109 char line[PATH_MAX + 100]; 2110 2111 // Read line by line from 'file' 2112 while (fgets(line, sizeof(line), procmapsFile) != NULL) { 2113 u8 base, top, offset, inode; 2114 char permissions[5]; 2115 char device[6]; 2116 char name[PATH_MAX + 1]; 2117 2118 // Parse fields from line 2119 sscanf(line, "%lx-%lx %4s %lx %5s %ld %s", &base, &top, permissions, &offset, device, &inode, name); 2120 2121 // Filter by device id '00:00' so that we only get file system mapped files. 2122 if (strcmp(device, "00:00") != 0) { 2123 2124 // Call callback with the fields of interest 2125 if(callback(name, (address)base, (address)top, param)) { 2126 // Oops abort, callback aborted 2127 fclose(procmapsFile); 2128 return 1; 2129 } 2130 } 2131 } 2132 fclose(procmapsFile); 2133 } 2134 return 0; 2135 } 2136 2137 void os::print_os_info_brief(outputStream* st) { 2138 os::Linux::print_distro_info(st); 2139 2140 os::Posix::print_uname_info(st); 2141 2142 os::Linux::print_libversion_info(st); 2143 2144 } 2145 2146 void os::print_os_info(outputStream* st) { 2147 st->print("OS:"); 2148 2149 os::Linux::print_distro_info(st); 2150 2151 os::Posix::print_uname_info(st); 2152 2153 // Print warning if unsafe chroot environment detected 2154 if (unsafe_chroot_detected) { 2155 st->print("WARNING!! "); 2156 st->print_cr("%s", unstable_chroot_error); 2157 } 2158 2159 os::Linux::print_libversion_info(st); 2160 2161 os::Posix::print_rlimit_info(st); 2162 2163 os::Posix::print_load_average(st); 2164 2165 os::Linux::print_full_memory_info(st); 2166 } 2167 2168 // Try to identify popular distros. 2169 // Most Linux distributions have a /etc/XXX-release file, which contains 2170 // the OS version string. Newer Linux distributions have a /etc/lsb-release 2171 // file that also contains the OS version string. Some have more than one 2172 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2173 // /etc/redhat-release.), so the order is important. 2174 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2175 // their own specific XXX-release file as well as a redhat-release file. 2176 // Because of this the XXX-release file needs to be searched for before the 2177 // redhat-release file. 2178 // Since Red Hat has a lsb-release file that is not very descriptive the 2179 // search for redhat-release needs to be before lsb-release. 2180 // Since the lsb-release file is the new standard it needs to be searched 2181 // before the older style release files. 2182 // Searching system-release (Red Hat) and os-release (other Linuxes) are a 2183 // next to last resort. The os-release file is a new standard that contains 2184 // distribution information and the system-release file seems to be an old 2185 // standard that has been replaced by the lsb-release and os-release files. 2186 // Searching for the debian_version file is the last resort. It contains 2187 // an informative string like "6.0.6" or "wheezy/sid". Because of this 2188 // "Debian " is printed before the contents of the debian_version file. 2189 void os::Linux::print_distro_info(outputStream* st) { 2190 if (!_print_ascii_file("/etc/oracle-release", st) && 2191 !_print_ascii_file("/etc/mandriva-release", st) && 2192 !_print_ascii_file("/etc/mandrake-release", st) && 2193 !_print_ascii_file("/etc/sun-release", st) && 2194 !_print_ascii_file("/etc/redhat-release", st) && 2195 !_print_ascii_file("/etc/lsb-release", st) && 2196 !_print_ascii_file("/etc/SuSE-release", st) && 2197 !_print_ascii_file("/etc/turbolinux-release", st) && 2198 !_print_ascii_file("/etc/gentoo-release", st) && 2199 !_print_ascii_file("/etc/ltib-release", st) && 2200 !_print_ascii_file("/etc/angstrom-version", st) && 2201 !_print_ascii_file("/etc/system-release", st) && 2202 !_print_ascii_file("/etc/os-release", st)) { 2203 2204 if (file_exists("/etc/debian_version")) { 2205 st->print("Debian "); 2206 _print_ascii_file("/etc/debian_version", st); 2207 } else { 2208 st->print("Linux"); 2209 } 2210 } 2211 st->cr(); 2212 } 2213 2214 void os::Linux::print_libversion_info(outputStream* st) { 2215 // libc, pthread 2216 st->print("libc:"); 2217 st->print("%s ", os::Linux::glibc_version()); 2218 st->print("%s ", os::Linux::libpthread_version()); 2219 if (os::Linux::is_LinuxThreads()) { 2220 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2221 } 2222 st->cr(); 2223 } 2224 2225 void os::Linux::print_full_memory_info(outputStream* st) { 2226 st->print("\n/proc/meminfo:\n"); 2227 _print_ascii_file("/proc/meminfo", st); 2228 st->cr(); 2229 } 2230 2231 void os::print_memory_info(outputStream* st) { 2232 2233 st->print("Memory:"); 2234 st->print(" %dk page", os::vm_page_size()>>10); 2235 2236 // values in struct sysinfo are "unsigned long" 2237 struct sysinfo si; 2238 sysinfo(&si); 2239 2240 st->print(", physical " UINT64_FORMAT "k", 2241 os::physical_memory() >> 10); 2242 st->print("(" UINT64_FORMAT "k free)", 2243 os::available_memory() >> 10); 2244 st->print(", swap " UINT64_FORMAT "k", 2245 ((jlong)si.totalswap * si.mem_unit) >> 10); 2246 st->print("(" UINT64_FORMAT "k free)", 2247 ((jlong)si.freeswap * si.mem_unit) >> 10); 2248 st->cr(); 2249 } 2250 2251 void os::pd_print_cpu_info(outputStream* st) { 2252 st->print("\n/proc/cpuinfo:\n"); 2253 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2254 st->print(" <Not Available>"); 2255 } 2256 st->cr(); 2257 } 2258 2259 void os::print_siginfo(outputStream* st, void* siginfo) { 2260 const siginfo_t* si = (const siginfo_t*)siginfo; 2261 2262 os::Posix::print_siginfo_brief(st, si); 2263 #if INCLUDE_CDS 2264 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2265 UseSharedSpaces) { 2266 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2267 if (mapinfo->is_in_shared_space(si->si_addr)) { 2268 st->print("\n\nError accessing class data sharing archive." \ 2269 " Mapped file inaccessible during execution, " \ 2270 " possible disk/network problem."); 2271 } 2272 } 2273 #endif 2274 st->cr(); 2275 } 2276 2277 2278 static void print_signal_handler(outputStream* st, int sig, 2279 char* buf, size_t buflen); 2280 2281 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2282 st->print_cr("Signal Handlers:"); 2283 print_signal_handler(st, SIGSEGV, buf, buflen); 2284 print_signal_handler(st, SIGBUS , buf, buflen); 2285 print_signal_handler(st, SIGFPE , buf, buflen); 2286 print_signal_handler(st, SIGPIPE, buf, buflen); 2287 print_signal_handler(st, SIGXFSZ, buf, buflen); 2288 print_signal_handler(st, SIGILL , buf, buflen); 2289 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2290 print_signal_handler(st, SR_signum, buf, buflen); 2291 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2292 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2293 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2294 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2295 #if defined(PPC64) 2296 print_signal_handler(st, SIGTRAP, buf, buflen); 2297 #endif 2298 } 2299 2300 static char saved_jvm_path[MAXPATHLEN] = {0}; 2301 2302 // Find the full path to the current module, libjvm.so 2303 void os::jvm_path(char *buf, jint buflen) { 2304 // Error checking. 2305 if (buflen < MAXPATHLEN) { 2306 assert(false, "must use a large-enough buffer"); 2307 buf[0] = '\0'; 2308 return; 2309 } 2310 // Lazy resolve the path to current module. 2311 if (saved_jvm_path[0] != 0) { 2312 strcpy(buf, saved_jvm_path); 2313 return; 2314 } 2315 2316 char dli_fname[MAXPATHLEN]; 2317 bool ret = dll_address_to_library_name( 2318 CAST_FROM_FN_PTR(address, os::jvm_path), 2319 dli_fname, sizeof(dli_fname), NULL); 2320 assert(ret, "cannot locate libjvm"); 2321 char *rp = NULL; 2322 if (ret && dli_fname[0] != '\0') { 2323 rp = realpath(dli_fname, buf); 2324 } 2325 if (rp == NULL) { 2326 return; 2327 } 2328 2329 if (Arguments::sun_java_launcher_is_altjvm()) { 2330 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical 2331 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". 2332 // If "/jre/lib/" appears at the right place in the string, then 2333 // assume we are installed in a JDK and we're done. Otherwise, check 2334 // for a JAVA_HOME environment variable and fix up the path so it 2335 // looks like libjvm.so is installed there (append a fake suffix 2336 // hotspot/libjvm.so). 2337 const char *p = buf + strlen(buf) - 1; 2338 for (int count = 0; p > buf && count < 5; ++count) { 2339 for (--p; p > buf && *p != '/'; --p) 2340 /* empty */ ; 2341 } 2342 2343 if (strncmp(p, "/jre/lib/", 9) != 0) { 2344 // Look for JAVA_HOME in the environment. 2345 char* java_home_var = ::getenv("JAVA_HOME"); 2346 if (java_home_var != NULL && java_home_var[0] != 0) { 2347 char* jrelib_p; 2348 int len; 2349 2350 // Check the current module name "libjvm.so". 2351 p = strrchr(buf, '/'); 2352 if (p == NULL) { 2353 return; 2354 } 2355 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2356 2357 rp = realpath(java_home_var, buf); 2358 if (rp == NULL) { 2359 return; 2360 } 2361 2362 // determine if this is a legacy image or modules image 2363 // modules image doesn't have "jre" subdirectory 2364 len = strlen(buf); 2365 assert(len < buflen, "Ran out of buffer room"); 2366 jrelib_p = buf + len; 2367 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2368 if (0 != access(buf, F_OK)) { 2369 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2370 } 2371 2372 if (0 == access(buf, F_OK)) { 2373 // Use current module name "libjvm.so" 2374 len = strlen(buf); 2375 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2376 } else { 2377 // Go back to path of .so 2378 rp = realpath(dli_fname, buf); 2379 if (rp == NULL) { 2380 return; 2381 } 2382 } 2383 } 2384 } 2385 } 2386 2387 strncpy(saved_jvm_path, buf, MAXPATHLEN); 2388 saved_jvm_path[MAXPATHLEN - 1] = '\0'; 2389 } 2390 2391 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2392 // no prefix required, not even "_" 2393 } 2394 2395 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2396 // no suffix required 2397 } 2398 2399 //////////////////////////////////////////////////////////////////////////////// 2400 // sun.misc.Signal support 2401 2402 static volatile jint sigint_count = 0; 2403 2404 static void UserHandler(int sig, void *siginfo, void *context) { 2405 // 4511530 - sem_post is serialized and handled by the manager thread. When 2406 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2407 // don't want to flood the manager thread with sem_post requests. 2408 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) { 2409 return; 2410 } 2411 2412 // Ctrl-C is pressed during error reporting, likely because the error 2413 // handler fails to abort. Let VM die immediately. 2414 if (sig == SIGINT && is_error_reported()) { 2415 os::die(); 2416 } 2417 2418 os::signal_notify(sig); 2419 } 2420 2421 void* os::user_handler() { 2422 return CAST_FROM_FN_PTR(void*, UserHandler); 2423 } 2424 2425 class Semaphore : public StackObj { 2426 public: 2427 Semaphore(); 2428 ~Semaphore(); 2429 void signal(); 2430 void wait(); 2431 bool trywait(); 2432 bool timedwait(unsigned int sec, int nsec); 2433 private: 2434 sem_t _semaphore; 2435 }; 2436 2437 Semaphore::Semaphore() { 2438 sem_init(&_semaphore, 0, 0); 2439 } 2440 2441 Semaphore::~Semaphore() { 2442 sem_destroy(&_semaphore); 2443 } 2444 2445 void Semaphore::signal() { 2446 sem_post(&_semaphore); 2447 } 2448 2449 void Semaphore::wait() { 2450 sem_wait(&_semaphore); 2451 } 2452 2453 bool Semaphore::trywait() { 2454 return sem_trywait(&_semaphore) == 0; 2455 } 2456 2457 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2458 2459 struct timespec ts; 2460 // Semaphore's are always associated with CLOCK_REALTIME 2461 os::Linux::clock_gettime(CLOCK_REALTIME, &ts); 2462 // see unpackTime for discussion on overflow checking 2463 if (sec >= MAX_SECS) { 2464 ts.tv_sec += MAX_SECS; 2465 ts.tv_nsec = 0; 2466 } else { 2467 ts.tv_sec += sec; 2468 ts.tv_nsec += nsec; 2469 if (ts.tv_nsec >= NANOSECS_PER_SEC) { 2470 ts.tv_nsec -= NANOSECS_PER_SEC; 2471 ++ts.tv_sec; // note: this must be <= max_secs 2472 } 2473 } 2474 2475 while (1) { 2476 int result = sem_timedwait(&_semaphore, &ts); 2477 if (result == 0) { 2478 return true; 2479 } else if (errno == EINTR) { 2480 continue; 2481 } else if (errno == ETIMEDOUT) { 2482 return false; 2483 } else { 2484 return false; 2485 } 2486 } 2487 } 2488 2489 extern "C" { 2490 typedef void (*sa_handler_t)(int); 2491 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2492 } 2493 2494 void* os::signal(int signal_number, void* handler) { 2495 struct sigaction sigAct, oldSigAct; 2496 2497 sigfillset(&(sigAct.sa_mask)); 2498 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2499 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2500 2501 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2502 // -1 means registration failed 2503 return (void *)-1; 2504 } 2505 2506 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2507 } 2508 2509 void os::signal_raise(int signal_number) { 2510 ::raise(signal_number); 2511 } 2512 2513 // The following code is moved from os.cpp for making this 2514 // code platform specific, which it is by its very nature. 2515 2516 // Will be modified when max signal is changed to be dynamic 2517 int os::sigexitnum_pd() { 2518 return NSIG; 2519 } 2520 2521 // a counter for each possible signal value 2522 static volatile jint pending_signals[NSIG+1] = { 0 }; 2523 2524 // Linux(POSIX) specific hand shaking semaphore. 2525 static sem_t sig_sem; 2526 static Semaphore sr_semaphore; 2527 2528 void os::signal_init_pd() { 2529 // Initialize signal structures 2530 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2531 2532 // Initialize signal semaphore 2533 ::sem_init(&sig_sem, 0, 0); 2534 } 2535 2536 void os::signal_notify(int sig) { 2537 Atomic::inc(&pending_signals[sig]); 2538 ::sem_post(&sig_sem); 2539 } 2540 2541 static int check_pending_signals(bool wait) { 2542 Atomic::store(0, &sigint_count); 2543 for (;;) { 2544 for (int i = 0; i < NSIG + 1; i++) { 2545 jint n = pending_signals[i]; 2546 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2547 return i; 2548 } 2549 } 2550 if (!wait) { 2551 return -1; 2552 } 2553 JavaThread *thread = JavaThread::current(); 2554 ThreadBlockInVM tbivm(thread); 2555 2556 bool threadIsSuspended; 2557 do { 2558 thread->set_suspend_equivalent(); 2559 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2560 ::sem_wait(&sig_sem); 2561 2562 // were we externally suspended while we were waiting? 2563 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2564 if (threadIsSuspended) { 2565 // The semaphore has been incremented, but while we were waiting 2566 // another thread suspended us. We don't want to continue running 2567 // while suspended because that would surprise the thread that 2568 // suspended us. 2569 ::sem_post(&sig_sem); 2570 2571 thread->java_suspend_self(); 2572 } 2573 } while (threadIsSuspended); 2574 } 2575 } 2576 2577 int os::signal_lookup() { 2578 return check_pending_signals(false); 2579 } 2580 2581 int os::signal_wait() { 2582 return check_pending_signals(true); 2583 } 2584 2585 //////////////////////////////////////////////////////////////////////////////// 2586 // Virtual Memory 2587 2588 int os::vm_page_size() { 2589 // Seems redundant as all get out 2590 assert(os::Linux::page_size() != -1, "must call os::init"); 2591 return os::Linux::page_size(); 2592 } 2593 2594 // Solaris allocates memory by pages. 2595 int os::vm_allocation_granularity() { 2596 assert(os::Linux::page_size() != -1, "must call os::init"); 2597 return os::Linux::page_size(); 2598 } 2599 2600 // Rationale behind this function: 2601 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2602 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2603 // samples for JITted code. Here we create private executable mapping over the code cache 2604 // and then we can use standard (well, almost, as mapping can change) way to provide 2605 // info for the reporting script by storing timestamp and location of symbol 2606 void linux_wrap_code(char* base, size_t size) { 2607 static volatile jint cnt = 0; 2608 2609 if (!UseOprofile) { 2610 return; 2611 } 2612 2613 char buf[PATH_MAX+1]; 2614 int num = Atomic::add(1, &cnt); 2615 2616 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2617 os::get_temp_directory(), os::current_process_id(), num); 2618 unlink(buf); 2619 2620 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2621 2622 if (fd != -1) { 2623 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2624 if (rv != (off_t)-1) { 2625 if (::write(fd, "", 1) == 1) { 2626 mmap(base, size, 2627 PROT_READ|PROT_WRITE|PROT_EXEC, 2628 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2629 } 2630 } 2631 ::close(fd); 2632 unlink(buf); 2633 } 2634 } 2635 2636 static bool recoverable_mmap_error(int err) { 2637 // See if the error is one we can let the caller handle. This 2638 // list of errno values comes from JBS-6843484. I can't find a 2639 // Linux man page that documents this specific set of errno 2640 // values so while this list currently matches Solaris, it may 2641 // change as we gain experience with this failure mode. 2642 switch (err) { 2643 case EBADF: 2644 case EINVAL: 2645 case ENOTSUP: 2646 // let the caller deal with these errors 2647 return true; 2648 2649 default: 2650 // Any remaining errors on this OS can cause our reserved mapping 2651 // to be lost. That can cause confusion where different data 2652 // structures think they have the same memory mapped. The worst 2653 // scenario is if both the VM and a library think they have the 2654 // same memory mapped. 2655 return false; 2656 } 2657 } 2658 2659 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2660 int err) { 2661 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2662 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2663 strerror(err), err); 2664 } 2665 2666 static void warn_fail_commit_memory(char* addr, size_t size, 2667 size_t alignment_hint, bool exec, 2668 int err) { 2669 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2670 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2671 alignment_hint, exec, strerror(err), err); 2672 } 2673 2674 // NOTE: Linux kernel does not really reserve the pages for us. 2675 // All it does is to check if there are enough free pages 2676 // left at the time of mmap(). This could be a potential 2677 // problem. 2678 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2679 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2680 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2681 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2682 if (res != (uintptr_t) MAP_FAILED) { 2683 if (UseNUMAInterleaving) { 2684 numa_make_global(addr, size); 2685 } 2686 return 0; 2687 } 2688 2689 int err = errno; // save errno from mmap() call above 2690 2691 if (!recoverable_mmap_error(err)) { 2692 warn_fail_commit_memory(addr, size, exec, err); 2693 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2694 } 2695 2696 return err; 2697 } 2698 2699 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2700 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2701 } 2702 2703 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2704 const char* mesg) { 2705 assert(mesg != NULL, "mesg must be specified"); 2706 int err = os::Linux::commit_memory_impl(addr, size, exec); 2707 if (err != 0) { 2708 // the caller wants all commit errors to exit with the specified mesg: 2709 warn_fail_commit_memory(addr, size, exec, err); 2710 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2711 } 2712 } 2713 2714 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2715 #ifndef MAP_HUGETLB 2716 #define MAP_HUGETLB 0x40000 2717 #endif 2718 2719 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2720 #ifndef MADV_HUGEPAGE 2721 #define MADV_HUGEPAGE 14 2722 #endif 2723 2724 int os::Linux::commit_memory_impl(char* addr, size_t size, 2725 size_t alignment_hint, bool exec) { 2726 int err = os::Linux::commit_memory_impl(addr, size, exec); 2727 if (err == 0) { 2728 realign_memory(addr, size, alignment_hint); 2729 } 2730 return err; 2731 } 2732 2733 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2734 bool exec) { 2735 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2736 } 2737 2738 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2739 size_t alignment_hint, bool exec, 2740 const char* mesg) { 2741 assert(mesg != NULL, "mesg must be specified"); 2742 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2743 if (err != 0) { 2744 // the caller wants all commit errors to exit with the specified mesg: 2745 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2746 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2747 } 2748 } 2749 2750 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2751 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2752 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2753 // be supported or the memory may already be backed by huge pages. 2754 ::madvise(addr, bytes, MADV_HUGEPAGE); 2755 } 2756 } 2757 2758 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2759 // This method works by doing an mmap over an existing mmaping and effectively discarding 2760 // the existing pages. However it won't work for SHM-based large pages that cannot be 2761 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2762 // small pages on top of the SHM segment. This method always works for small pages, so we 2763 // allow that in any case. 2764 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2765 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2766 } 2767 } 2768 2769 void os::numa_make_global(char *addr, size_t bytes) { 2770 Linux::numa_interleave_memory(addr, bytes); 2771 } 2772 2773 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2774 // bind policy to MPOL_PREFERRED for the current thread. 2775 #define USE_MPOL_PREFERRED 0 2776 2777 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2778 // To make NUMA and large pages more robust when both enabled, we need to ease 2779 // the requirements on where the memory should be allocated. MPOL_BIND is the 2780 // default policy and it will force memory to be allocated on the specified 2781 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2782 // the specified node, but will not force it. Using this policy will prevent 2783 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2784 // free large pages. 2785 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2786 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2787 } 2788 2789 bool os::numa_topology_changed() { return false; } 2790 2791 size_t os::numa_get_groups_num() { 2792 int max_node = Linux::numa_max_node(); 2793 return max_node > 0 ? max_node + 1 : 1; 2794 } 2795 2796 int os::numa_get_group_id() { 2797 int cpu_id = Linux::sched_getcpu(); 2798 if (cpu_id != -1) { 2799 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2800 if (lgrp_id != -1) { 2801 return lgrp_id; 2802 } 2803 } 2804 return 0; 2805 } 2806 2807 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2808 for (size_t i = 0; i < size; i++) { 2809 ids[i] = i; 2810 } 2811 return size; 2812 } 2813 2814 bool os::get_page_info(char *start, page_info* info) { 2815 return false; 2816 } 2817 2818 char *os::scan_pages(char *start, char* end, page_info* page_expected, 2819 page_info* page_found) { 2820 return end; 2821 } 2822 2823 2824 int os::Linux::sched_getcpu_syscall(void) { 2825 unsigned int cpu; 2826 int retval = -1; 2827 2828 #if defined(IA32) 2829 #ifndef SYS_getcpu 2830 #define SYS_getcpu 318 2831 #endif 2832 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2833 #elif defined(AMD64) 2834 // Unfortunately we have to bring all these macros here from vsyscall.h 2835 // to be able to compile on old linuxes. 2836 #define __NR_vgetcpu 2 2837 #define VSYSCALL_START (-10UL << 20) 2838 #define VSYSCALL_SIZE 1024 2839 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2840 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2841 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2842 retval = vgetcpu(&cpu, NULL, NULL); 2843 #endif 2844 2845 return (retval == -1) ? retval : cpu; 2846 } 2847 2848 // Something to do with the numa-aware allocator needs these symbols 2849 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2850 extern "C" JNIEXPORT void numa_error(char *where) { } 2851 extern "C" JNIEXPORT int fork1() { return fork(); } 2852 2853 2854 // If we are running with libnuma version > 2, then we should 2855 // be trying to use symbols with versions 1.1 2856 // If we are running with earlier version, which did not have symbol versions, 2857 // we should use the base version. 2858 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2859 void *f = dlvsym(handle, name, "libnuma_1.1"); 2860 if (f == NULL) { 2861 f = dlsym(handle, name); 2862 } 2863 return f; 2864 } 2865 2866 bool os::Linux::libnuma_init() { 2867 // sched_getcpu() should be in libc. 2868 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2869 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2870 2871 // If it's not, try a direct syscall. 2872 if (sched_getcpu() == -1) { 2873 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2874 (void*)&sched_getcpu_syscall)); 2875 } 2876 2877 if (sched_getcpu() != -1) { // Does it work? 2878 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2879 if (handle != NULL) { 2880 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2881 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2882 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2883 libnuma_dlsym(handle, "numa_max_node"))); 2884 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2885 libnuma_dlsym(handle, "numa_available"))); 2886 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2887 libnuma_dlsym(handle, "numa_tonode_memory"))); 2888 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2889 libnuma_dlsym(handle, "numa_interleave_memory"))); 2890 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2891 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2892 2893 2894 if (numa_available() != -1) { 2895 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2896 // Create a cpu -> node mapping 2897 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2898 rebuild_cpu_to_node_map(); 2899 return true; 2900 } 2901 } 2902 } 2903 return false; 2904 } 2905 2906 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2907 // The table is later used in get_node_by_cpu(). 2908 void os::Linux::rebuild_cpu_to_node_map() { 2909 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2910 // in libnuma (possible values are starting from 16, 2911 // and continuing up with every other power of 2, but less 2912 // than the maximum number of CPUs supported by kernel), and 2913 // is a subject to change (in libnuma version 2 the requirements 2914 // are more reasonable) we'll just hardcode the number they use 2915 // in the library. 2916 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2917 2918 size_t cpu_num = os::active_processor_count(); 2919 size_t cpu_map_size = NCPUS / BitsPerCLong; 2920 size_t cpu_map_valid_size = 2921 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2922 2923 cpu_to_node()->clear(); 2924 cpu_to_node()->at_grow(cpu_num - 1); 2925 size_t node_num = numa_get_groups_num(); 2926 2927 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2928 for (size_t i = 0; i < node_num; i++) { 2929 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2930 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2931 if (cpu_map[j] != 0) { 2932 for (size_t k = 0; k < BitsPerCLong; k++) { 2933 if (cpu_map[j] & (1UL << k)) { 2934 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2935 } 2936 } 2937 } 2938 } 2939 } 2940 } 2941 FREE_C_HEAP_ARRAY(unsigned long, cpu_map); 2942 } 2943 2944 int os::Linux::get_node_by_cpu(int cpu_id) { 2945 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2946 return cpu_to_node()->at(cpu_id); 2947 } 2948 return -1; 2949 } 2950 2951 GrowableArray<int>* os::Linux::_cpu_to_node; 2952 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2953 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2954 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2955 os::Linux::numa_available_func_t os::Linux::_numa_available; 2956 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2957 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2958 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2959 unsigned long* os::Linux::_numa_all_nodes; 2960 2961 bool os::pd_uncommit_memory(char* addr, size_t size) { 2962 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2963 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2964 return res != (uintptr_t) MAP_FAILED; 2965 } 2966 2967 static address get_stack_commited_bottom(address bottom, size_t size) { 2968 address nbot = bottom; 2969 address ntop = bottom + size; 2970 2971 size_t page_sz = os::vm_page_size(); 2972 unsigned pages = size / page_sz; 2973 2974 unsigned char vec[1]; 2975 unsigned imin = 1, imax = pages + 1, imid; 2976 int mincore_return_value = 0; 2977 2978 assert(imin <= imax, "Unexpected page size"); 2979 2980 while (imin < imax) { 2981 imid = (imax + imin) / 2; 2982 nbot = ntop - (imid * page_sz); 2983 2984 // Use a trick with mincore to check whether the page is mapped or not. 2985 // mincore sets vec to 1 if page resides in memory and to 0 if page 2986 // is swapped output but if page we are asking for is unmapped 2987 // it returns -1,ENOMEM 2988 mincore_return_value = mincore(nbot, page_sz, vec); 2989 2990 if (mincore_return_value == -1) { 2991 // Page is not mapped go up 2992 // to find first mapped page 2993 if (errno != EAGAIN) { 2994 assert(errno == ENOMEM, "Unexpected mincore errno"); 2995 imax = imid; 2996 } 2997 } else { 2998 // Page is mapped go down 2999 // to find first not mapped page 3000 imin = imid + 1; 3001 } 3002 } 3003 3004 nbot = nbot + page_sz; 3005 3006 // Adjust stack bottom one page up if last checked page is not mapped 3007 if (mincore_return_value == -1) { 3008 nbot = nbot + page_sz; 3009 } 3010 3011 return nbot; 3012 } 3013 3014 3015 // Linux uses a growable mapping for the stack, and if the mapping for 3016 // the stack guard pages is not removed when we detach a thread the 3017 // stack cannot grow beyond the pages where the stack guard was 3018 // mapped. If at some point later in the process the stack expands to 3019 // that point, the Linux kernel cannot expand the stack any further 3020 // because the guard pages are in the way, and a segfault occurs. 3021 // 3022 // However, it's essential not to split the stack region by unmapping 3023 // a region (leaving a hole) that's already part of the stack mapping, 3024 // so if the stack mapping has already grown beyond the guard pages at 3025 // the time we create them, we have to truncate the stack mapping. 3026 // So, we need to know the extent of the stack mapping when 3027 // create_stack_guard_pages() is called. 3028 3029 // We only need this for stacks that are growable: at the time of 3030 // writing thread stacks don't use growable mappings (i.e. those 3031 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 3032 // only applies to the main thread. 3033 3034 // If the (growable) stack mapping already extends beyond the point 3035 // where we're going to put our guard pages, truncate the mapping at 3036 // that point by munmap()ping it. This ensures that when we later 3037 // munmap() the guard pages we don't leave a hole in the stack 3038 // mapping. This only affects the main/initial thread 3039 3040 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3041 if (os::Linux::is_initial_thread()) { 3042 // As we manually grow stack up to bottom inside create_attached_thread(), 3043 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3044 // we don't need to do anything special. 3045 // Check it first, before calling heavy function. 3046 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3047 unsigned char vec[1]; 3048 3049 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3050 // Fallback to slow path on all errors, including EAGAIN 3051 stack_extent = (uintptr_t) get_stack_commited_bottom( 3052 os::Linux::initial_thread_stack_bottom(), 3053 (size_t)addr - stack_extent); 3054 } 3055 3056 if (stack_extent < (uintptr_t)addr) { 3057 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3058 } 3059 } 3060 3061 return os::commit_memory(addr, size, !ExecMem); 3062 } 3063 3064 // If this is a growable mapping, remove the guard pages entirely by 3065 // munmap()ping them. If not, just call uncommit_memory(). This only 3066 // affects the main/initial thread, but guard against future OS changes 3067 // It's safe to always unmap guard pages for initial thread because we 3068 // always place it right after end of the mapped region 3069 3070 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3071 uintptr_t stack_extent, stack_base; 3072 3073 if (os::Linux::is_initial_thread()) { 3074 return ::munmap(addr, size) == 0; 3075 } 3076 3077 return os::uncommit_memory(addr, size); 3078 } 3079 3080 static address _highest_vm_reserved_address = NULL; 3081 3082 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3083 // at 'requested_addr'. If there are existing memory mappings at the same 3084 // location, however, they will be overwritten. If 'fixed' is false, 3085 // 'requested_addr' is only treated as a hint, the return value may or 3086 // may not start from the requested address. Unlike Linux mmap(), this 3087 // function returns NULL to indicate failure. 3088 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3089 char * addr; 3090 int flags; 3091 3092 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3093 if (fixed) { 3094 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3095 flags |= MAP_FIXED; 3096 } 3097 3098 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3099 // touch an uncommitted page. Otherwise, the read/write might 3100 // succeed if we have enough swap space to back the physical page. 3101 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3102 flags, -1, 0); 3103 3104 if (addr != MAP_FAILED) { 3105 // anon_mmap() should only get called during VM initialization, 3106 // don't need lock (actually we can skip locking even it can be called 3107 // from multiple threads, because _highest_vm_reserved_address is just a 3108 // hint about the upper limit of non-stack memory regions.) 3109 if ((address)addr + bytes > _highest_vm_reserved_address) { 3110 _highest_vm_reserved_address = (address)addr + bytes; 3111 } 3112 } 3113 3114 return addr == MAP_FAILED ? NULL : addr; 3115 } 3116 3117 // Don't update _highest_vm_reserved_address, because there might be memory 3118 // regions above addr + size. If so, releasing a memory region only creates 3119 // a hole in the address space, it doesn't help prevent heap-stack collision. 3120 // 3121 static int anon_munmap(char * addr, size_t size) { 3122 return ::munmap(addr, size) == 0; 3123 } 3124 3125 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3126 size_t alignment_hint) { 3127 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3128 } 3129 3130 bool os::pd_release_memory(char* addr, size_t size) { 3131 return anon_munmap(addr, size); 3132 } 3133 3134 static address highest_vm_reserved_address() { 3135 return _highest_vm_reserved_address; 3136 } 3137 3138 static bool linux_mprotect(char* addr, size_t size, int prot) { 3139 // Linux wants the mprotect address argument to be page aligned. 3140 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3141 3142 // According to SUSv3, mprotect() should only be used with mappings 3143 // established by mmap(), and mmap() always maps whole pages. Unaligned 3144 // 'addr' likely indicates problem in the VM (e.g. trying to change 3145 // protection of malloc'ed or statically allocated memory). Check the 3146 // caller if you hit this assert. 3147 assert(addr == bottom, "sanity check"); 3148 3149 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3150 return ::mprotect(bottom, size, prot) == 0; 3151 } 3152 3153 // Set protections specified 3154 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3155 bool is_committed) { 3156 unsigned int p = 0; 3157 switch (prot) { 3158 case MEM_PROT_NONE: p = PROT_NONE; break; 3159 case MEM_PROT_READ: p = PROT_READ; break; 3160 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3161 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3162 default: 3163 ShouldNotReachHere(); 3164 } 3165 // is_committed is unused. 3166 return linux_mprotect(addr, bytes, p); 3167 } 3168 3169 bool os::guard_memory(char* addr, size_t size) { 3170 return linux_mprotect(addr, size, PROT_NONE); 3171 } 3172 3173 bool os::unguard_memory(char* addr, size_t size) { 3174 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3175 } 3176 3177 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, 3178 size_t page_size) { 3179 bool result = false; 3180 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3181 MAP_ANONYMOUS|MAP_PRIVATE, 3182 -1, 0); 3183 if (p != MAP_FAILED) { 3184 void *aligned_p = align_ptr_up(p, page_size); 3185 3186 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3187 3188 munmap(p, page_size * 2); 3189 } 3190 3191 if (warn && !result) { 3192 warning("TransparentHugePages is not supported by the operating system."); 3193 } 3194 3195 return result; 3196 } 3197 3198 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3199 bool result = false; 3200 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3201 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3202 -1, 0); 3203 3204 if (p != MAP_FAILED) { 3205 // We don't know if this really is a huge page or not. 3206 FILE *fp = fopen("/proc/self/maps", "r"); 3207 if (fp) { 3208 while (!feof(fp)) { 3209 char chars[257]; 3210 long x = 0; 3211 if (fgets(chars, sizeof(chars), fp)) { 3212 if (sscanf(chars, "%lx-%*x", &x) == 1 3213 && x == (long)p) { 3214 if (strstr (chars, "hugepage")) { 3215 result = true; 3216 break; 3217 } 3218 } 3219 } 3220 } 3221 fclose(fp); 3222 } 3223 munmap(p, page_size); 3224 } 3225 3226 if (warn && !result) { 3227 warning("HugeTLBFS is not supported by the operating system."); 3228 } 3229 3230 return result; 3231 } 3232 3233 // Set the coredump_filter bits to include largepages in core dump (bit 6) 3234 // 3235 // From the coredump_filter documentation: 3236 // 3237 // - (bit 0) anonymous private memory 3238 // - (bit 1) anonymous shared memory 3239 // - (bit 2) file-backed private memory 3240 // - (bit 3) file-backed shared memory 3241 // - (bit 4) ELF header pages in file-backed private memory areas (it is 3242 // effective only if the bit 2 is cleared) 3243 // - (bit 5) hugetlb private memory 3244 // - (bit 6) hugetlb shared memory 3245 // 3246 static void set_coredump_filter(void) { 3247 FILE *f; 3248 long cdm; 3249 3250 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3251 return; 3252 } 3253 3254 if (fscanf(f, "%lx", &cdm) != 1) { 3255 fclose(f); 3256 return; 3257 } 3258 3259 rewind(f); 3260 3261 if ((cdm & LARGEPAGES_BIT) == 0) { 3262 cdm |= LARGEPAGES_BIT; 3263 fprintf(f, "%#lx", cdm); 3264 } 3265 3266 fclose(f); 3267 } 3268 3269 // Large page support 3270 3271 static size_t _large_page_size = 0; 3272 3273 size_t os::Linux::find_large_page_size() { 3274 size_t large_page_size = 0; 3275 3276 // large_page_size on Linux is used to round up heap size. x86 uses either 3277 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3278 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3279 // page as large as 256M. 3280 // 3281 // Here we try to figure out page size by parsing /proc/meminfo and looking 3282 // for a line with the following format: 3283 // Hugepagesize: 2048 kB 3284 // 3285 // If we can't determine the value (e.g. /proc is not mounted, or the text 3286 // format has been changed), we'll use the largest page size supported by 3287 // the processor. 3288 3289 #ifndef ZERO 3290 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3291 ARM_ONLY(2 * M) PPC_ONLY(4 * M); 3292 #endif // ZERO 3293 3294 FILE *fp = fopen("/proc/meminfo", "r"); 3295 if (fp) { 3296 while (!feof(fp)) { 3297 int x = 0; 3298 char buf[16]; 3299 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3300 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3301 large_page_size = x * K; 3302 break; 3303 } 3304 } else { 3305 // skip to next line 3306 for (;;) { 3307 int ch = fgetc(fp); 3308 if (ch == EOF || ch == (int)'\n') break; 3309 } 3310 } 3311 } 3312 fclose(fp); 3313 } 3314 3315 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3316 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3317 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3318 proper_unit_for_byte_size(large_page_size)); 3319 } 3320 3321 return large_page_size; 3322 } 3323 3324 size_t os::Linux::setup_large_page_size() { 3325 _large_page_size = Linux::find_large_page_size(); 3326 const size_t default_page_size = (size_t)Linux::page_size(); 3327 if (_large_page_size > default_page_size) { 3328 _page_sizes[0] = _large_page_size; 3329 _page_sizes[1] = default_page_size; 3330 _page_sizes[2] = 0; 3331 } 3332 3333 return _large_page_size; 3334 } 3335 3336 bool os::Linux::setup_large_page_type(size_t page_size) { 3337 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3338 FLAG_IS_DEFAULT(UseSHM) && 3339 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3340 3341 // The type of large pages has not been specified by the user. 3342 3343 // Try UseHugeTLBFS and then UseSHM. 3344 UseHugeTLBFS = UseSHM = true; 3345 3346 // Don't try UseTransparentHugePages since there are known 3347 // performance issues with it turned on. This might change in the future. 3348 UseTransparentHugePages = false; 3349 } 3350 3351 if (UseTransparentHugePages) { 3352 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3353 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3354 UseHugeTLBFS = false; 3355 UseSHM = false; 3356 return true; 3357 } 3358 UseTransparentHugePages = false; 3359 } 3360 3361 if (UseHugeTLBFS) { 3362 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3363 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3364 UseSHM = false; 3365 return true; 3366 } 3367 UseHugeTLBFS = false; 3368 } 3369 3370 return UseSHM; 3371 } 3372 3373 void os::large_page_init() { 3374 if (!UseLargePages && 3375 !UseTransparentHugePages && 3376 !UseHugeTLBFS && 3377 !UseSHM) { 3378 // Not using large pages. 3379 return; 3380 } 3381 3382 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3383 // The user explicitly turned off large pages. 3384 // Ignore the rest of the large pages flags. 3385 UseTransparentHugePages = false; 3386 UseHugeTLBFS = false; 3387 UseSHM = false; 3388 return; 3389 } 3390 3391 size_t large_page_size = Linux::setup_large_page_size(); 3392 UseLargePages = Linux::setup_large_page_type(large_page_size); 3393 3394 set_coredump_filter(); 3395 } 3396 3397 #ifndef SHM_HUGETLB 3398 #define SHM_HUGETLB 04000 3399 #endif 3400 3401 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, 3402 char* req_addr, bool exec) { 3403 // "exec" is passed in but not used. Creating the shared image for 3404 // the code cache doesn't have an SHM_X executable permission to check. 3405 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3406 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3407 3408 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3409 return NULL; // Fallback to small pages. 3410 } 3411 3412 key_t key = IPC_PRIVATE; 3413 char *addr; 3414 3415 bool warn_on_failure = UseLargePages && 3416 (!FLAG_IS_DEFAULT(UseLargePages) || 3417 !FLAG_IS_DEFAULT(UseSHM) || 3418 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3419 char msg[128]; 3420 3421 // Create a large shared memory region to attach to based on size. 3422 // Currently, size is the total size of the heap 3423 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3424 if (shmid == -1) { 3425 // Possible reasons for shmget failure: 3426 // 1. shmmax is too small for Java heap. 3427 // > check shmmax value: cat /proc/sys/kernel/shmmax 3428 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3429 // 2. not enough large page memory. 3430 // > check available large pages: cat /proc/meminfo 3431 // > increase amount of large pages: 3432 // echo new_value > /proc/sys/vm/nr_hugepages 3433 // Note 1: different Linux may use different name for this property, 3434 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3435 // Note 2: it's possible there's enough physical memory available but 3436 // they are so fragmented after a long run that they can't 3437 // coalesce into large pages. Try to reserve large pages when 3438 // the system is still "fresh". 3439 if (warn_on_failure) { 3440 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3441 warning("%s", msg); 3442 } 3443 return NULL; 3444 } 3445 3446 // attach to the region 3447 addr = (char*)shmat(shmid, req_addr, 0); 3448 int err = errno; 3449 3450 // Remove shmid. If shmat() is successful, the actual shared memory segment 3451 // will be deleted when it's detached by shmdt() or when the process 3452 // terminates. If shmat() is not successful this will remove the shared 3453 // segment immediately. 3454 shmctl(shmid, IPC_RMID, NULL); 3455 3456 if ((intptr_t)addr == -1) { 3457 if (warn_on_failure) { 3458 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3459 warning("%s", msg); 3460 } 3461 return NULL; 3462 } 3463 3464 return addr; 3465 } 3466 3467 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, 3468 int error) { 3469 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3470 3471 bool warn_on_failure = UseLargePages && 3472 (!FLAG_IS_DEFAULT(UseLargePages) || 3473 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3474 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3475 3476 if (warn_on_failure) { 3477 char msg[128]; 3478 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3479 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3480 warning("%s", msg); 3481 } 3482 } 3483 3484 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, 3485 char* req_addr, 3486 bool exec) { 3487 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3488 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3489 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3490 3491 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3492 char* addr = (char*)::mmap(req_addr, bytes, prot, 3493 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3494 -1, 0); 3495 3496 if (addr == MAP_FAILED) { 3497 warn_on_large_pages_failure(req_addr, bytes, errno); 3498 return NULL; 3499 } 3500 3501 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3502 3503 return addr; 3504 } 3505 3506 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, 3507 size_t alignment, 3508 char* req_addr, 3509 bool exec) { 3510 size_t large_page_size = os::large_page_size(); 3511 3512 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3513 3514 // Allocate small pages. 3515 3516 char* start; 3517 if (req_addr != NULL) { 3518 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3519 assert(is_size_aligned(bytes, alignment), "Must be"); 3520 start = os::reserve_memory(bytes, req_addr); 3521 assert(start == NULL || start == req_addr, "Must be"); 3522 } else { 3523 start = os::reserve_memory_aligned(bytes, alignment); 3524 } 3525 3526 if (start == NULL) { 3527 return NULL; 3528 } 3529 3530 assert(is_ptr_aligned(start, alignment), "Must be"); 3531 3532 if (MemTracker::tracking_level() > NMT_minimal) { 3533 // os::reserve_memory_special will record this memory area. 3534 // Need to release it here to prevent overlapping reservations. 3535 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3536 tkr.record((address)start, bytes); 3537 } 3538 3539 char* end = start + bytes; 3540 3541 // Find the regions of the allocated chunk that can be promoted to large pages. 3542 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3543 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3544 3545 size_t lp_bytes = lp_end - lp_start; 3546 3547 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3548 3549 if (lp_bytes == 0) { 3550 // The mapped region doesn't even span the start and the end of a large page. 3551 // Fall back to allocate a non-special area. 3552 ::munmap(start, end - start); 3553 return NULL; 3554 } 3555 3556 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3557 3558 3559 void* result; 3560 3561 if (start != lp_start) { 3562 result = ::mmap(start, lp_start - start, prot, 3563 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3564 -1, 0); 3565 if (result == MAP_FAILED) { 3566 ::munmap(lp_start, end - lp_start); 3567 return NULL; 3568 } 3569 } 3570 3571 result = ::mmap(lp_start, lp_bytes, prot, 3572 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3573 -1, 0); 3574 if (result == MAP_FAILED) { 3575 warn_on_large_pages_failure(req_addr, bytes, errno); 3576 // If the mmap above fails, the large pages region will be unmapped and we 3577 // have regions before and after with small pages. Release these regions. 3578 // 3579 // | mapped | unmapped | mapped | 3580 // ^ ^ ^ ^ 3581 // start lp_start lp_end end 3582 // 3583 ::munmap(start, lp_start - start); 3584 ::munmap(lp_end, end - lp_end); 3585 return NULL; 3586 } 3587 3588 if (lp_end != end) { 3589 result = ::mmap(lp_end, end - lp_end, prot, 3590 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3591 -1, 0); 3592 if (result == MAP_FAILED) { 3593 ::munmap(start, lp_end - start); 3594 return NULL; 3595 } 3596 } 3597 3598 return start; 3599 } 3600 3601 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, 3602 size_t alignment, 3603 char* req_addr, 3604 bool exec) { 3605 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3606 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3607 assert(is_power_of_2(alignment), "Must be"); 3608 assert(is_power_of_2(os::large_page_size()), "Must be"); 3609 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3610 3611 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3612 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3613 } else { 3614 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3615 } 3616 } 3617 3618 char* os::reserve_memory_special(size_t bytes, size_t alignment, 3619 char* req_addr, bool exec) { 3620 assert(UseLargePages, "only for large pages"); 3621 3622 char* addr; 3623 if (UseSHM) { 3624 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3625 } else { 3626 assert(UseHugeTLBFS, "must be"); 3627 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3628 } 3629 3630 if (addr != NULL) { 3631 if (UseNUMAInterleaving) { 3632 numa_make_global(addr, bytes); 3633 } 3634 3635 // The memory is committed 3636 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC); 3637 } 3638 3639 return addr; 3640 } 3641 3642 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3643 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3644 return shmdt(base) == 0; 3645 } 3646 3647 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3648 return pd_release_memory(base, bytes); 3649 } 3650 3651 bool os::release_memory_special(char* base, size_t bytes) { 3652 bool res; 3653 if (MemTracker::tracking_level() > NMT_minimal) { 3654 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3655 res = os::Linux::release_memory_special_impl(base, bytes); 3656 if (res) { 3657 tkr.record((address)base, bytes); 3658 } 3659 3660 } else { 3661 res = os::Linux::release_memory_special_impl(base, bytes); 3662 } 3663 return res; 3664 } 3665 3666 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) { 3667 assert(UseLargePages, "only for large pages"); 3668 bool res; 3669 3670 if (UseSHM) { 3671 res = os::Linux::release_memory_special_shm(base, bytes); 3672 } else { 3673 assert(UseHugeTLBFS, "must be"); 3674 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3675 } 3676 return res; 3677 } 3678 3679 size_t os::large_page_size() { 3680 return _large_page_size; 3681 } 3682 3683 // With SysV SHM the entire memory region must be allocated as shared 3684 // memory. 3685 // HugeTLBFS allows application to commit large page memory on demand. 3686 // However, when committing memory with HugeTLBFS fails, the region 3687 // that was supposed to be committed will lose the old reservation 3688 // and allow other threads to steal that memory region. Because of this 3689 // behavior we can't commit HugeTLBFS memory. 3690 bool os::can_commit_large_page_memory() { 3691 return UseTransparentHugePages; 3692 } 3693 3694 bool os::can_execute_large_page_memory() { 3695 return UseTransparentHugePages || UseHugeTLBFS; 3696 } 3697 3698 // Reserve memory at an arbitrary address, only if that area is 3699 // available (and not reserved for something else). 3700 3701 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3702 const int max_tries = 10; 3703 char* base[max_tries]; 3704 size_t size[max_tries]; 3705 const size_t gap = 0x000000; 3706 3707 // Assert only that the size is a multiple of the page size, since 3708 // that's all that mmap requires, and since that's all we really know 3709 // about at this low abstraction level. If we need higher alignment, 3710 // we can either pass an alignment to this method or verify alignment 3711 // in one of the methods further up the call chain. See bug 5044738. 3712 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3713 3714 // Repeatedly allocate blocks until the block is allocated at the 3715 // right spot. Give up after max_tries. Note that reserve_memory() will 3716 // automatically update _highest_vm_reserved_address if the call is 3717 // successful. The variable tracks the highest memory address every reserved 3718 // by JVM. It is used to detect heap-stack collision if running with 3719 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3720 // space than needed, it could confuse the collision detecting code. To 3721 // solve the problem, save current _highest_vm_reserved_address and 3722 // calculate the correct value before return. 3723 address old_highest = _highest_vm_reserved_address; 3724 3725 // Linux mmap allows caller to pass an address as hint; give it a try first, 3726 // if kernel honors the hint then we can return immediately. 3727 char * addr = anon_mmap(requested_addr, bytes, false); 3728 if (addr == requested_addr) { 3729 return requested_addr; 3730 } 3731 3732 if (addr != NULL) { 3733 // mmap() is successful but it fails to reserve at the requested address 3734 anon_munmap(addr, bytes); 3735 } 3736 3737 int i; 3738 for (i = 0; i < max_tries; ++i) { 3739 base[i] = reserve_memory(bytes); 3740 3741 if (base[i] != NULL) { 3742 // Is this the block we wanted? 3743 if (base[i] == requested_addr) { 3744 size[i] = bytes; 3745 break; 3746 } 3747 3748 // Does this overlap the block we wanted? Give back the overlapped 3749 // parts and try again. 3750 3751 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3752 if (top_overlap >= 0 && top_overlap < bytes) { 3753 unmap_memory(base[i], top_overlap); 3754 base[i] += top_overlap; 3755 size[i] = bytes - top_overlap; 3756 } else { 3757 size_t bottom_overlap = base[i] + bytes - requested_addr; 3758 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3759 unmap_memory(requested_addr, bottom_overlap); 3760 size[i] = bytes - bottom_overlap; 3761 } else { 3762 size[i] = bytes; 3763 } 3764 } 3765 } 3766 } 3767 3768 // Give back the unused reserved pieces. 3769 3770 for (int j = 0; j < i; ++j) { 3771 if (base[j] != NULL) { 3772 unmap_memory(base[j], size[j]); 3773 } 3774 } 3775 3776 if (i < max_tries) { 3777 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3778 return requested_addr; 3779 } else { 3780 _highest_vm_reserved_address = old_highest; 3781 return NULL; 3782 } 3783 } 3784 3785 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3786 return ::read(fd, buf, nBytes); 3787 } 3788 3789 size_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) { 3790 return ::pread(fd, buf, nBytes, offset); 3791 } 3792 3793 // Short sleep, direct OS call. 3794 // 3795 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee 3796 // sched_yield(2) will actually give up the CPU: 3797 // 3798 // * Alone on this pariticular CPU, keeps running. 3799 // * Before the introduction of "skip_buddy" with "compat_yield" disabled 3800 // (pre 2.6.39). 3801 // 3802 // So calling this with 0 is an alternative. 3803 // 3804 void os::naked_short_sleep(jlong ms) { 3805 struct timespec req; 3806 3807 assert(ms < 1000, "Un-interruptable sleep, short time use only"); 3808 req.tv_sec = 0; 3809 if (ms > 0) { 3810 req.tv_nsec = (ms % 1000) * 1000000; 3811 } else { 3812 req.tv_nsec = 1; 3813 } 3814 3815 nanosleep(&req, NULL); 3816 3817 return; 3818 } 3819 3820 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3821 void os::infinite_sleep() { 3822 while (true) { // sleep forever ... 3823 ::sleep(100); // ... 100 seconds at a time 3824 } 3825 } 3826 3827 // Used to convert frequent JVM_Yield() to nops 3828 bool os::dont_yield() { 3829 return DontYieldALot; 3830 } 3831 3832 void os::naked_yield() { 3833 sched_yield(); 3834 } 3835 3836 //////////////////////////////////////////////////////////////////////////////// 3837 // thread priority support 3838 3839 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3840 // only supports dynamic priority, static priority must be zero. For real-time 3841 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3842 // However, for large multi-threaded applications, SCHED_RR is not only slower 3843 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3844 // of 5 runs - Sep 2005). 3845 // 3846 // The following code actually changes the niceness of kernel-thread/LWP. It 3847 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3848 // not the entire user process, and user level threads are 1:1 mapped to kernel 3849 // threads. It has always been the case, but could change in the future. For 3850 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3851 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3852 3853 int os::java_to_os_priority[CriticalPriority + 1] = { 3854 19, // 0 Entry should never be used 3855 3856 4, // 1 MinPriority 3857 3, // 2 3858 2, // 3 3859 3860 1, // 4 3861 0, // 5 NormPriority 3862 -1, // 6 3863 3864 -2, // 7 3865 -3, // 8 3866 -4, // 9 NearMaxPriority 3867 3868 -5, // 10 MaxPriority 3869 3870 -5 // 11 CriticalPriority 3871 }; 3872 3873 static int prio_init() { 3874 if (ThreadPriorityPolicy == 1) { 3875 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3876 // if effective uid is not root. Perhaps, a more elegant way of doing 3877 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3878 if (geteuid() != 0) { 3879 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3880 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3881 } 3882 ThreadPriorityPolicy = 0; 3883 } 3884 } 3885 if (UseCriticalJavaThreadPriority) { 3886 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3887 } 3888 return 0; 3889 } 3890 3891 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3892 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK; 3893 3894 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3895 return (ret == 0) ? OS_OK : OS_ERR; 3896 } 3897 3898 OSReturn os::get_native_priority(const Thread* const thread, 3899 int *priority_ptr) { 3900 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) { 3901 *priority_ptr = java_to_os_priority[NormPriority]; 3902 return OS_OK; 3903 } 3904 3905 errno = 0; 3906 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3907 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3908 } 3909 3910 // Hint to the underlying OS that a task switch would not be good. 3911 // Void return because it's a hint and can fail. 3912 void os::hint_no_preempt() {} 3913 3914 //////////////////////////////////////////////////////////////////////////////// 3915 // suspend/resume support 3916 3917 // the low-level signal-based suspend/resume support is a remnant from the 3918 // old VM-suspension that used to be for java-suspension, safepoints etc, 3919 // within hotspot. Now there is a single use-case for this: 3920 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3921 // that runs in the watcher thread. 3922 // The remaining code is greatly simplified from the more general suspension 3923 // code that used to be used. 3924 // 3925 // The protocol is quite simple: 3926 // - suspend: 3927 // - sends a signal to the target thread 3928 // - polls the suspend state of the osthread using a yield loop 3929 // - target thread signal handler (SR_handler) sets suspend state 3930 // and blocks in sigsuspend until continued 3931 // - resume: 3932 // - sets target osthread state to continue 3933 // - sends signal to end the sigsuspend loop in the SR_handler 3934 // 3935 // Note that the SR_lock plays no role in this suspend/resume protocol. 3936 3937 static void resume_clear_context(OSThread *osthread) { 3938 osthread->set_ucontext(NULL); 3939 osthread->set_siginfo(NULL); 3940 } 3941 3942 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, 3943 ucontext_t* context) { 3944 osthread->set_ucontext(context); 3945 osthread->set_siginfo(siginfo); 3946 } 3947 3948 // Handler function invoked when a thread's execution is suspended or 3949 // resumed. We have to be careful that only async-safe functions are 3950 // called here (Note: most pthread functions are not async safe and 3951 // should be avoided.) 3952 // 3953 // Note: sigwait() is a more natural fit than sigsuspend() from an 3954 // interface point of view, but sigwait() prevents the signal hander 3955 // from being run. libpthread would get very confused by not having 3956 // its signal handlers run and prevents sigwait()'s use with the 3957 // mutex granting granting signal. 3958 // 3959 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 3960 // 3961 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3962 // Save and restore errno to avoid confusing native code with EINTR 3963 // after sigsuspend. 3964 int old_errno = errno; 3965 3966 Thread* thread = Thread::current(); 3967 OSThread* osthread = thread->osthread(); 3968 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 3969 3970 os::SuspendResume::State current = osthread->sr.state(); 3971 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 3972 suspend_save_context(osthread, siginfo, context); 3973 3974 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 3975 os::SuspendResume::State state = osthread->sr.suspended(); 3976 if (state == os::SuspendResume::SR_SUSPENDED) { 3977 sigset_t suspend_set; // signals for sigsuspend() 3978 3979 // get current set of blocked signals and unblock resume signal 3980 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3981 sigdelset(&suspend_set, SR_signum); 3982 3983 sr_semaphore.signal(); 3984 // wait here until we are resumed 3985 while (1) { 3986 sigsuspend(&suspend_set); 3987 3988 os::SuspendResume::State result = osthread->sr.running(); 3989 if (result == os::SuspendResume::SR_RUNNING) { 3990 sr_semaphore.signal(); 3991 break; 3992 } 3993 } 3994 3995 } else if (state == os::SuspendResume::SR_RUNNING) { 3996 // request was cancelled, continue 3997 } else { 3998 ShouldNotReachHere(); 3999 } 4000 4001 resume_clear_context(osthread); 4002 } else if (current == os::SuspendResume::SR_RUNNING) { 4003 // request was cancelled, continue 4004 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 4005 // ignore 4006 } else { 4007 // ignore 4008 } 4009 4010 errno = old_errno; 4011 } 4012 4013 4014 static int SR_initialize() { 4015 struct sigaction act; 4016 char *s; 4017 // Get signal number to use for suspend/resume 4018 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 4019 int sig = ::strtol(s, 0, 10); 4020 if (sig > 0 || sig < _NSIG) { 4021 SR_signum = sig; 4022 } 4023 } 4024 4025 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 4026 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 4027 4028 sigemptyset(&SR_sigset); 4029 sigaddset(&SR_sigset, SR_signum); 4030 4031 // Set up signal handler for suspend/resume 4032 act.sa_flags = SA_RESTART|SA_SIGINFO; 4033 act.sa_handler = (void (*)(int)) SR_handler; 4034 4035 // SR_signum is blocked by default. 4036 // 4528190 - We also need to block pthread restart signal (32 on all 4037 // supported Linux platforms). Note that LinuxThreads need to block 4038 // this signal for all threads to work properly. So we don't have 4039 // to use hard-coded signal number when setting up the mask. 4040 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4041 4042 if (sigaction(SR_signum, &act, 0) == -1) { 4043 return -1; 4044 } 4045 4046 // Save signal flag 4047 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4048 return 0; 4049 } 4050 4051 static int sr_notify(OSThread* osthread) { 4052 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4053 assert_status(status == 0, status, "pthread_kill"); 4054 return status; 4055 } 4056 4057 // "Randomly" selected value for how long we want to spin 4058 // before bailing out on suspending a thread, also how often 4059 // we send a signal to a thread we want to resume 4060 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4061 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4062 4063 // returns true on success and false on error - really an error is fatal 4064 // but this seems the normal response to library errors 4065 static bool do_suspend(OSThread* osthread) { 4066 assert(osthread->sr.is_running(), "thread should be running"); 4067 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4068 4069 // mark as suspended and send signal 4070 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4071 // failed to switch, state wasn't running? 4072 ShouldNotReachHere(); 4073 return false; 4074 } 4075 4076 if (sr_notify(osthread) != 0) { 4077 ShouldNotReachHere(); 4078 } 4079 4080 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4081 while (true) { 4082 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4083 break; 4084 } else { 4085 // timeout 4086 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4087 if (cancelled == os::SuspendResume::SR_RUNNING) { 4088 return false; 4089 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4090 // make sure that we consume the signal on the semaphore as well 4091 sr_semaphore.wait(); 4092 break; 4093 } else { 4094 ShouldNotReachHere(); 4095 return false; 4096 } 4097 } 4098 } 4099 4100 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4101 return true; 4102 } 4103 4104 static void do_resume(OSThread* osthread) { 4105 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4106 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4107 4108 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4109 // failed to switch to WAKEUP_REQUEST 4110 ShouldNotReachHere(); 4111 return; 4112 } 4113 4114 while (true) { 4115 if (sr_notify(osthread) == 0) { 4116 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4117 if (osthread->sr.is_running()) { 4118 return; 4119 } 4120 } 4121 } else { 4122 ShouldNotReachHere(); 4123 } 4124 } 4125 4126 guarantee(osthread->sr.is_running(), "Must be running!"); 4127 } 4128 4129 /////////////////////////////////////////////////////////////////////////////////// 4130 // signal handling (except suspend/resume) 4131 4132 // This routine may be used by user applications as a "hook" to catch signals. 4133 // The user-defined signal handler must pass unrecognized signals to this 4134 // routine, and if it returns true (non-zero), then the signal handler must 4135 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4136 // routine will never retun false (zero), but instead will execute a VM panic 4137 // routine kill the process. 4138 // 4139 // If this routine returns false, it is OK to call it again. This allows 4140 // the user-defined signal handler to perform checks either before or after 4141 // the VM performs its own checks. Naturally, the user code would be making 4142 // a serious error if it tried to handle an exception (such as a null check 4143 // or breakpoint) that the VM was generating for its own correct operation. 4144 // 4145 // This routine may recognize any of the following kinds of signals: 4146 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4147 // It should be consulted by handlers for any of those signals. 4148 // 4149 // The caller of this routine must pass in the three arguments supplied 4150 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4151 // field of the structure passed to sigaction(). This routine assumes that 4152 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4153 // 4154 // Note that the VM will print warnings if it detects conflicting signal 4155 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4156 // 4157 extern "C" JNIEXPORT int JVM_handle_linux_signal(int signo, 4158 siginfo_t* siginfo, 4159 void* ucontext, 4160 int abort_if_unrecognized); 4161 4162 void signalHandler(int sig, siginfo_t* info, void* uc) { 4163 assert(info != NULL && uc != NULL, "it must be old kernel"); 4164 int orig_errno = errno; // Preserve errno value over signal handler. 4165 JVM_handle_linux_signal(sig, info, uc, true); 4166 errno = orig_errno; 4167 } 4168 4169 4170 // This boolean allows users to forward their own non-matching signals 4171 // to JVM_handle_linux_signal, harmlessly. 4172 bool os::Linux::signal_handlers_are_installed = false; 4173 4174 // For signal-chaining 4175 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4176 unsigned int os::Linux::sigs = 0; 4177 bool os::Linux::libjsig_is_loaded = false; 4178 typedef struct sigaction *(*get_signal_t)(int); 4179 get_signal_t os::Linux::get_signal_action = NULL; 4180 4181 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4182 struct sigaction *actp = NULL; 4183 4184 if (libjsig_is_loaded) { 4185 // Retrieve the old signal handler from libjsig 4186 actp = (*get_signal_action)(sig); 4187 } 4188 if (actp == NULL) { 4189 // Retrieve the preinstalled signal handler from jvm 4190 actp = get_preinstalled_handler(sig); 4191 } 4192 4193 return actp; 4194 } 4195 4196 static bool call_chained_handler(struct sigaction *actp, int sig, 4197 siginfo_t *siginfo, void *context) { 4198 // Call the old signal handler 4199 if (actp->sa_handler == SIG_DFL) { 4200 // It's more reasonable to let jvm treat it as an unexpected exception 4201 // instead of taking the default action. 4202 return false; 4203 } else if (actp->sa_handler != SIG_IGN) { 4204 if ((actp->sa_flags & SA_NODEFER) == 0) { 4205 // automaticlly block the signal 4206 sigaddset(&(actp->sa_mask), sig); 4207 } 4208 4209 sa_handler_t hand; 4210 sa_sigaction_t sa; 4211 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4212 // retrieve the chained handler 4213 if (siginfo_flag_set) { 4214 sa = actp->sa_sigaction; 4215 } else { 4216 hand = actp->sa_handler; 4217 } 4218 4219 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4220 actp->sa_handler = SIG_DFL; 4221 } 4222 4223 // try to honor the signal mask 4224 sigset_t oset; 4225 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4226 4227 // call into the chained handler 4228 if (siginfo_flag_set) { 4229 (*sa)(sig, siginfo, context); 4230 } else { 4231 (*hand)(sig); 4232 } 4233 4234 // restore the signal mask 4235 pthread_sigmask(SIG_SETMASK, &oset, 0); 4236 } 4237 // Tell jvm's signal handler the signal is taken care of. 4238 return true; 4239 } 4240 4241 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4242 bool chained = false; 4243 // signal-chaining 4244 if (UseSignalChaining) { 4245 struct sigaction *actp = get_chained_signal_action(sig); 4246 if (actp != NULL) { 4247 chained = call_chained_handler(actp, sig, siginfo, context); 4248 } 4249 } 4250 return chained; 4251 } 4252 4253 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4254 if ((((unsigned int)1 << sig) & sigs) != 0) { 4255 return &sigact[sig]; 4256 } 4257 return NULL; 4258 } 4259 4260 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4261 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4262 sigact[sig] = oldAct; 4263 sigs |= (unsigned int)1 << sig; 4264 } 4265 4266 // for diagnostic 4267 int os::Linux::sigflags[MAXSIGNUM]; 4268 4269 int os::Linux::get_our_sigflags(int sig) { 4270 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4271 return sigflags[sig]; 4272 } 4273 4274 void os::Linux::set_our_sigflags(int sig, int flags) { 4275 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4276 sigflags[sig] = flags; 4277 } 4278 4279 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4280 // Check for overwrite. 4281 struct sigaction oldAct; 4282 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4283 4284 void* oldhand = oldAct.sa_sigaction 4285 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4286 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4287 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4288 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4289 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4290 if (AllowUserSignalHandlers || !set_installed) { 4291 // Do not overwrite; user takes responsibility to forward to us. 4292 return; 4293 } else if (UseSignalChaining) { 4294 // save the old handler in jvm 4295 save_preinstalled_handler(sig, oldAct); 4296 // libjsig also interposes the sigaction() call below and saves the 4297 // old sigaction on it own. 4298 } else { 4299 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4300 "%#lx for signal %d.", (long)oldhand, sig)); 4301 } 4302 } 4303 4304 struct sigaction sigAct; 4305 sigfillset(&(sigAct.sa_mask)); 4306 sigAct.sa_handler = SIG_DFL; 4307 if (!set_installed) { 4308 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4309 } else { 4310 sigAct.sa_sigaction = signalHandler; 4311 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4312 } 4313 // Save flags, which are set by ours 4314 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4315 sigflags[sig] = sigAct.sa_flags; 4316 4317 int ret = sigaction(sig, &sigAct, &oldAct); 4318 assert(ret == 0, "check"); 4319 4320 void* oldhand2 = oldAct.sa_sigaction 4321 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4322 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4323 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4324 } 4325 4326 // install signal handlers for signals that HotSpot needs to 4327 // handle in order to support Java-level exception handling. 4328 4329 void os::Linux::install_signal_handlers() { 4330 if (!signal_handlers_are_installed) { 4331 signal_handlers_are_installed = true; 4332 4333 // signal-chaining 4334 typedef void (*signal_setting_t)(); 4335 signal_setting_t begin_signal_setting = NULL; 4336 signal_setting_t end_signal_setting = NULL; 4337 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4338 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4339 if (begin_signal_setting != NULL) { 4340 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4341 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4342 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4343 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4344 libjsig_is_loaded = true; 4345 assert(UseSignalChaining, "should enable signal-chaining"); 4346 } 4347 if (libjsig_is_loaded) { 4348 // Tell libjsig jvm is setting signal handlers 4349 (*begin_signal_setting)(); 4350 } 4351 4352 set_signal_handler(SIGSEGV, true); 4353 set_signal_handler(SIGPIPE, true); 4354 set_signal_handler(SIGBUS, true); 4355 set_signal_handler(SIGILL, true); 4356 set_signal_handler(SIGFPE, true); 4357 #if defined(PPC64) 4358 set_signal_handler(SIGTRAP, true); 4359 #endif 4360 set_signal_handler(SIGXFSZ, true); 4361 4362 if (libjsig_is_loaded) { 4363 // Tell libjsig jvm finishes setting signal handlers 4364 (*end_signal_setting)(); 4365 } 4366 4367 // We don't activate signal checker if libjsig is in place, we trust ourselves 4368 // and if UserSignalHandler is installed all bets are off. 4369 // Log that signal checking is off only if -verbose:jni is specified. 4370 if (CheckJNICalls) { 4371 if (libjsig_is_loaded) { 4372 if (PrintJNIResolving) { 4373 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4374 } 4375 check_signals = false; 4376 } 4377 if (AllowUserSignalHandlers) { 4378 if (PrintJNIResolving) { 4379 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4380 } 4381 check_signals = false; 4382 } 4383 } 4384 } 4385 } 4386 4387 // This is the fastest way to get thread cpu time on Linux. 4388 // Returns cpu time (user+sys) for any thread, not only for current. 4389 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4390 // It might work on 2.6.10+ with a special kernel/glibc patch. 4391 // For reference, please, see IEEE Std 1003.1-2004: 4392 // http://www.unix.org/single_unix_specification 4393 4394 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4395 struct timespec tp; 4396 int rc = os::Linux::clock_gettime(clockid, &tp); 4397 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4398 4399 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4400 } 4401 4402 ///// 4403 // glibc on Linux platform uses non-documented flag 4404 // to indicate, that some special sort of signal 4405 // trampoline is used. 4406 // We will never set this flag, and we should 4407 // ignore this flag in our diagnostic 4408 #ifdef SIGNIFICANT_SIGNAL_MASK 4409 #undef SIGNIFICANT_SIGNAL_MASK 4410 #endif 4411 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4412 4413 static const char* get_signal_handler_name(address handler, 4414 char* buf, int buflen) { 4415 int offset; 4416 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4417 if (found) { 4418 // skip directory names 4419 const char *p1, *p2; 4420 p1 = buf; 4421 size_t len = strlen(os::file_separator()); 4422 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4423 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4424 } else { 4425 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4426 } 4427 return buf; 4428 } 4429 4430 static void print_signal_handler(outputStream* st, int sig, 4431 char* buf, size_t buflen) { 4432 struct sigaction sa; 4433 4434 sigaction(sig, NULL, &sa); 4435 4436 // See comment for SIGNIFICANT_SIGNAL_MASK define 4437 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4438 4439 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4440 4441 address handler = (sa.sa_flags & SA_SIGINFO) 4442 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4443 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4444 4445 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4446 st->print("SIG_DFL"); 4447 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4448 st->print("SIG_IGN"); 4449 } else { 4450 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4451 } 4452 4453 st->print(", sa_mask[0]="); 4454 os::Posix::print_signal_set_short(st, &sa.sa_mask); 4455 4456 address rh = VMError::get_resetted_sighandler(sig); 4457 // May be, handler was resetted by VMError? 4458 if (rh != NULL) { 4459 handler = rh; 4460 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4461 } 4462 4463 st->print(", sa_flags="); 4464 os::Posix::print_sa_flags(st, sa.sa_flags); 4465 4466 // Check: is it our handler? 4467 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4468 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4469 // It is our signal handler 4470 // check for flags, reset system-used one! 4471 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4472 st->print( 4473 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4474 os::Linux::get_our_sigflags(sig)); 4475 } 4476 } 4477 st->cr(); 4478 } 4479 4480 4481 #define DO_SIGNAL_CHECK(sig) \ 4482 do { \ 4483 if (!sigismember(&check_signal_done, sig)) { \ 4484 os::Linux::check_signal_handler(sig); \ 4485 } \ 4486 } while (0) 4487 4488 // This method is a periodic task to check for misbehaving JNI applications 4489 // under CheckJNI, we can add any periodic checks here 4490 4491 void os::run_periodic_checks() { 4492 if (check_signals == false) return; 4493 4494 // SEGV and BUS if overridden could potentially prevent 4495 // generation of hs*.log in the event of a crash, debugging 4496 // such a case can be very challenging, so we absolutely 4497 // check the following for a good measure: 4498 DO_SIGNAL_CHECK(SIGSEGV); 4499 DO_SIGNAL_CHECK(SIGILL); 4500 DO_SIGNAL_CHECK(SIGFPE); 4501 DO_SIGNAL_CHECK(SIGBUS); 4502 DO_SIGNAL_CHECK(SIGPIPE); 4503 DO_SIGNAL_CHECK(SIGXFSZ); 4504 #if defined(PPC64) 4505 DO_SIGNAL_CHECK(SIGTRAP); 4506 #endif 4507 4508 // ReduceSignalUsage allows the user to override these handlers 4509 // see comments at the very top and jvm_solaris.h 4510 if (!ReduceSignalUsage) { 4511 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4512 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4513 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4514 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4515 } 4516 4517 DO_SIGNAL_CHECK(SR_signum); 4518 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4519 } 4520 4521 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4522 4523 static os_sigaction_t os_sigaction = NULL; 4524 4525 void os::Linux::check_signal_handler(int sig) { 4526 char buf[O_BUFLEN]; 4527 address jvmHandler = NULL; 4528 4529 4530 struct sigaction act; 4531 if (os_sigaction == NULL) { 4532 // only trust the default sigaction, in case it has been interposed 4533 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4534 if (os_sigaction == NULL) return; 4535 } 4536 4537 os_sigaction(sig, (struct sigaction*)NULL, &act); 4538 4539 4540 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4541 4542 address thisHandler = (act.sa_flags & SA_SIGINFO) 4543 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4544 : CAST_FROM_FN_PTR(address, act.sa_handler); 4545 4546 4547 switch (sig) { 4548 case SIGSEGV: 4549 case SIGBUS: 4550 case SIGFPE: 4551 case SIGPIPE: 4552 case SIGILL: 4553 case SIGXFSZ: 4554 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4555 break; 4556 4557 case SHUTDOWN1_SIGNAL: 4558 case SHUTDOWN2_SIGNAL: 4559 case SHUTDOWN3_SIGNAL: 4560 case BREAK_SIGNAL: 4561 jvmHandler = (address)user_handler(); 4562 break; 4563 4564 case INTERRUPT_SIGNAL: 4565 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4566 break; 4567 4568 default: 4569 if (sig == SR_signum) { 4570 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4571 } else { 4572 return; 4573 } 4574 break; 4575 } 4576 4577 if (thisHandler != jvmHandler) { 4578 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4579 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4580 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4581 // No need to check this sig any longer 4582 sigaddset(&check_signal_done, sig); 4583 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN 4584 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) { 4585 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell", 4586 exception_name(sig, buf, O_BUFLEN)); 4587 } 4588 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4589 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4590 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4591 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4592 // No need to check this sig any longer 4593 sigaddset(&check_signal_done, sig); 4594 } 4595 4596 // Dump all the signal 4597 if (sigismember(&check_signal_done, sig)) { 4598 print_signal_handlers(tty, buf, O_BUFLEN); 4599 } 4600 } 4601 4602 extern void report_error(char* file_name, int line_no, char* title, 4603 char* format, ...); 4604 4605 extern bool signal_name(int signo, char* buf, size_t len); 4606 4607 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4608 if (0 < exception_code && exception_code <= SIGRTMAX) { 4609 // signal 4610 if (!signal_name(exception_code, buf, size)) { 4611 jio_snprintf(buf, size, "SIG%d", exception_code); 4612 } 4613 return buf; 4614 } else { 4615 return NULL; 4616 } 4617 } 4618 4619 // this is called _before_ the most of global arguments have been parsed 4620 void os::init(void) { 4621 char dummy; // used to get a guess on initial stack address 4622 // first_hrtime = gethrtime(); 4623 4624 // With LinuxThreads the JavaMain thread pid (primordial thread) 4625 // is different than the pid of the java launcher thread. 4626 // So, on Linux, the launcher thread pid is passed to the VM 4627 // via the sun.java.launcher.pid property. 4628 // Use this property instead of getpid() if it was correctly passed. 4629 // See bug 6351349. 4630 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4631 4632 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4633 4634 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4635 4636 init_random(1234567); 4637 4638 ThreadCritical::initialize(); 4639 4640 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4641 if (Linux::page_size() == -1) { 4642 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4643 strerror(errno))); 4644 } 4645 init_page_sizes((size_t) Linux::page_size()); 4646 4647 Linux::initialize_system_info(); 4648 4649 // main_thread points to the aboriginal thread 4650 Linux::_main_thread = pthread_self(); 4651 4652 Linux::clock_init(); 4653 initial_time_count = javaTimeNanos(); 4654 4655 // pthread_condattr initialization for monotonic clock 4656 int status; 4657 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4658 if ((status = pthread_condattr_init(_condattr)) != 0) { 4659 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4660 } 4661 // Only set the clock if CLOCK_MONOTONIC is available 4662 if (os::supports_monotonic_clock()) { 4663 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4664 if (status == EINVAL) { 4665 warning("Unable to use monotonic clock with relative timed-waits" \ 4666 " - changes to the time-of-day clock may have adverse affects"); 4667 } else { 4668 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4669 } 4670 } 4671 } 4672 // else it defaults to CLOCK_REALTIME 4673 4674 pthread_mutex_init(&dl_mutex, NULL); 4675 4676 // If the pagesize of the VM is greater than 8K determine the appropriate 4677 // number of initial guard pages. The user can change this with the 4678 // command line arguments, if needed. 4679 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4680 StackYellowPages = 1; 4681 StackRedPages = 1; 4682 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4683 } 4684 4685 // retrieve entry point for pthread_setname_np 4686 Linux::_pthread_setname_np = 4687 (int(*)(pthread_t, const char*))dlsym(RTLD_DEFAULT, "pthread_setname_np"); 4688 4689 } 4690 4691 // To install functions for atexit system call 4692 extern "C" { 4693 static void perfMemory_exit_helper() { 4694 perfMemory_exit(); 4695 } 4696 } 4697 4698 // this is called _after_ the global arguments have been parsed 4699 jint os::init_2(void) { 4700 Linux::fast_thread_clock_init(); 4701 4702 // Allocate a single page and mark it as readable for safepoint polling 4703 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4704 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page"); 4705 4706 os::set_polling_page(polling_page); 4707 4708 #ifndef PRODUCT 4709 if (Verbose && PrintMiscellaneous) { 4710 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", 4711 (intptr_t)polling_page); 4712 } 4713 #endif 4714 4715 if (!UseMembar) { 4716 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4717 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4718 os::set_memory_serialize_page(mem_serialize_page); 4719 4720 #ifndef PRODUCT 4721 if (Verbose && PrintMiscellaneous) { 4722 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", 4723 (intptr_t)mem_serialize_page); 4724 } 4725 #endif 4726 } 4727 4728 // initialize suspend/resume support - must do this before signal_sets_init() 4729 if (SR_initialize() != 0) { 4730 perror("SR_initialize failed"); 4731 return JNI_ERR; 4732 } 4733 4734 Linux::signal_sets_init(); 4735 Linux::install_signal_handlers(); 4736 4737 // Check minimum allowable stack size for thread creation and to initialize 4738 // the java system classes, including StackOverflowError - depends on page 4739 // size. Add a page for compiler2 recursion in main thread. 4740 // Add in 2*BytesPerWord times page size to account for VM stack during 4741 // class initialization depending on 32 or 64 bit VM. 4742 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4743 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4744 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4745 4746 size_t threadStackSizeInBytes = ThreadStackSize * K; 4747 if (threadStackSizeInBytes != 0 && 4748 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4749 tty->print_cr("\nThe stack size specified is too small, " 4750 "Specify at least %dk", 4751 os::Linux::min_stack_allowed/ K); 4752 return JNI_ERR; 4753 } 4754 4755 // Make the stack size a multiple of the page size so that 4756 // the yellow/red zones can be guarded. 4757 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4758 vm_page_size())); 4759 4760 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4761 4762 #if defined(IA32) 4763 workaround_expand_exec_shield_cs_limit(); 4764 #endif 4765 4766 Linux::libpthread_init(); 4767 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4768 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4769 Linux::glibc_version(), Linux::libpthread_version(), 4770 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4771 } 4772 4773 if (UseNUMA) { 4774 if (!Linux::libnuma_init()) { 4775 UseNUMA = false; 4776 } else { 4777 if ((Linux::numa_max_node() < 1)) { 4778 // There's only one node(they start from 0), disable NUMA. 4779 UseNUMA = false; 4780 } 4781 } 4782 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4783 // we can make the adaptive lgrp chunk resizing work. If the user specified 4784 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4785 // disable adaptive resizing. 4786 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4787 if (FLAG_IS_DEFAULT(UseNUMA)) { 4788 UseNUMA = false; 4789 } else { 4790 if (FLAG_IS_DEFAULT(UseLargePages) && 4791 FLAG_IS_DEFAULT(UseSHM) && 4792 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4793 UseLargePages = false; 4794 } else { 4795 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4796 UseAdaptiveSizePolicy = false; 4797 UseAdaptiveNUMAChunkSizing = false; 4798 } 4799 } 4800 } 4801 if (!UseNUMA && ForceNUMA) { 4802 UseNUMA = true; 4803 } 4804 } 4805 4806 if (MaxFDLimit) { 4807 // set the number of file descriptors to max. print out error 4808 // if getrlimit/setrlimit fails but continue regardless. 4809 struct rlimit nbr_files; 4810 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4811 if (status != 0) { 4812 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4813 perror("os::init_2 getrlimit failed"); 4814 } 4815 } else { 4816 nbr_files.rlim_cur = nbr_files.rlim_max; 4817 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4818 if (status != 0) { 4819 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4820 perror("os::init_2 setrlimit failed"); 4821 } 4822 } 4823 } 4824 } 4825 4826 // Initialize lock used to serialize thread creation (see os::create_thread) 4827 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4828 4829 // at-exit methods are called in the reverse order of their registration. 4830 // atexit functions are called on return from main or as a result of a 4831 // call to exit(3C). There can be only 32 of these functions registered 4832 // and atexit() does not set errno. 4833 4834 if (PerfAllowAtExitRegistration) { 4835 // only register atexit functions if PerfAllowAtExitRegistration is set. 4836 // atexit functions can be delayed until process exit time, which 4837 // can be problematic for embedded VM situations. Embedded VMs should 4838 // call DestroyJavaVM() to assure that VM resources are released. 4839 4840 // note: perfMemory_exit_helper atexit function may be removed in 4841 // the future if the appropriate cleanup code can be added to the 4842 // VM_Exit VMOperation's doit method. 4843 if (atexit(perfMemory_exit_helper) != 0) { 4844 warning("os::init_2 atexit(perfMemory_exit_helper) failed"); 4845 } 4846 } 4847 4848 // initialize thread priority policy 4849 prio_init(); 4850 4851 return JNI_OK; 4852 } 4853 4854 // Mark the polling page as unreadable 4855 void os::make_polling_page_unreadable(void) { 4856 if (!guard_memory((char*)_polling_page, Linux::page_size())) { 4857 fatal("Could not disable polling page"); 4858 } 4859 } 4860 4861 // Mark the polling page as readable 4862 void os::make_polling_page_readable(void) { 4863 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4864 fatal("Could not enable polling page"); 4865 } 4866 } 4867 4868 int os::active_processor_count() { 4869 // Linux doesn't yet have a (official) notion of processor sets, 4870 // so just return the number of online processors. 4871 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4872 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4873 return online_cpus; 4874 } 4875 4876 void os::set_native_thread_name(const char *name) { 4877 if (Linux::_pthread_setname_np) { 4878 char buf [16]; // according to glibc manpage, 16 chars incl. '/0' 4879 snprintf(buf, sizeof(buf), "%s", name); 4880 buf[sizeof(buf) - 1] = '\0'; 4881 const int rc = Linux::_pthread_setname_np(pthread_self(), buf); 4882 // ERANGE should not happen; all other errors should just be ignored. 4883 assert(rc != ERANGE, "pthread_setname_np failed"); 4884 } 4885 } 4886 4887 bool os::distribute_processes(uint length, uint* distribution) { 4888 // Not yet implemented. 4889 return false; 4890 } 4891 4892 bool os::bind_to_processor(uint processor_id) { 4893 // Not yet implemented. 4894 return false; 4895 } 4896 4897 /// 4898 4899 void os::SuspendedThreadTask::internal_do_task() { 4900 if (do_suspend(_thread->osthread())) { 4901 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4902 do_task(context); 4903 do_resume(_thread->osthread()); 4904 } 4905 } 4906 4907 class PcFetcher : public os::SuspendedThreadTask { 4908 public: 4909 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4910 ExtendedPC result(); 4911 protected: 4912 void do_task(const os::SuspendedThreadTaskContext& context); 4913 private: 4914 ExtendedPC _epc; 4915 }; 4916 4917 ExtendedPC PcFetcher::result() { 4918 guarantee(is_done(), "task is not done yet."); 4919 return _epc; 4920 } 4921 4922 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 4923 Thread* thread = context.thread(); 4924 OSThread* osthread = thread->osthread(); 4925 if (osthread->ucontext() != NULL) { 4926 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 4927 } else { 4928 // NULL context is unexpected, double-check this is the VMThread 4929 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4930 } 4931 } 4932 4933 // Suspends the target using the signal mechanism and then grabs the PC before 4934 // resuming the target. Used by the flat-profiler only 4935 ExtendedPC os::get_thread_pc(Thread* thread) { 4936 // Make sure that it is called by the watcher for the VMThread 4937 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4938 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4939 4940 PcFetcher fetcher(thread); 4941 fetcher.run(); 4942 return fetcher.result(); 4943 } 4944 4945 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, 4946 pthread_mutex_t *_mutex, 4947 const struct timespec *_abstime) { 4948 if (is_NPTL()) { 4949 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4950 } else { 4951 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4952 // word back to default 64bit precision if condvar is signaled. Java 4953 // wants 53bit precision. Save and restore current value. 4954 int fpu = get_fpu_control_word(); 4955 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4956 set_fpu_control_word(fpu); 4957 return status; 4958 } 4959 } 4960 4961 //////////////////////////////////////////////////////////////////////////////// 4962 // debug support 4963 4964 bool os::find(address addr, outputStream* st) { 4965 Dl_info dlinfo; 4966 memset(&dlinfo, 0, sizeof(dlinfo)); 4967 if (dladdr(addr, &dlinfo) != 0) { 4968 st->print(PTR_FORMAT ": ", addr); 4969 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 4970 st->print("%s+%#x", dlinfo.dli_sname, 4971 addr - (intptr_t)dlinfo.dli_saddr); 4972 } else if (dlinfo.dli_fbase != NULL) { 4973 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4974 } else { 4975 st->print("<absolute address>"); 4976 } 4977 if (dlinfo.dli_fname != NULL) { 4978 st->print(" in %s", dlinfo.dli_fname); 4979 } 4980 if (dlinfo.dli_fbase != NULL) { 4981 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4982 } 4983 st->cr(); 4984 4985 if (Verbose) { 4986 // decode some bytes around the PC 4987 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 4988 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 4989 address lowest = (address) dlinfo.dli_sname; 4990 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4991 if (begin < lowest) begin = lowest; 4992 Dl_info dlinfo2; 4993 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 4994 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) { 4995 end = (address) dlinfo2.dli_saddr; 4996 } 4997 Disassembler::decode(begin, end, st); 4998 } 4999 return true; 5000 } 5001 return false; 5002 } 5003 5004 //////////////////////////////////////////////////////////////////////////////// 5005 // misc 5006 5007 // This does not do anything on Linux. This is basically a hook for being 5008 // able to use structured exception handling (thread-local exception filters) 5009 // on, e.g., Win32. 5010 void 5011 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 5012 JavaCallArguments* args, Thread* thread) { 5013 f(value, method, args, thread); 5014 } 5015 5016 void os::print_statistics() { 5017 } 5018 5019 int os::message_box(const char* title, const char* message) { 5020 int i; 5021 fdStream err(defaultStream::error_fd()); 5022 for (i = 0; i < 78; i++) err.print_raw("="); 5023 err.cr(); 5024 err.print_raw_cr(title); 5025 for (i = 0; i < 78; i++) err.print_raw("-"); 5026 err.cr(); 5027 err.print_raw_cr(message); 5028 for (i = 0; i < 78; i++) err.print_raw("="); 5029 err.cr(); 5030 5031 char buf[16]; 5032 // Prevent process from exiting upon "read error" without consuming all CPU 5033 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 5034 5035 return buf[0] == 'y' || buf[0] == 'Y'; 5036 } 5037 5038 int os::stat(const char *path, struct stat *sbuf) { 5039 char pathbuf[MAX_PATH]; 5040 if (strlen(path) > MAX_PATH - 1) { 5041 errno = ENAMETOOLONG; 5042 return -1; 5043 } 5044 os::native_path(strcpy(pathbuf, path)); 5045 return ::stat(pathbuf, sbuf); 5046 } 5047 5048 bool os::check_heap(bool force) { 5049 return true; 5050 } 5051 5052 // Is a (classpath) directory empty? 5053 bool os::dir_is_empty(const char* path) { 5054 DIR *dir = NULL; 5055 struct dirent *ptr; 5056 5057 dir = opendir(path); 5058 if (dir == NULL) return true; 5059 5060 // Scan the directory 5061 bool result = true; 5062 char buf[sizeof(struct dirent) + MAX_PATH]; 5063 while (result && (ptr = ::readdir(dir)) != NULL) { 5064 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5065 result = false; 5066 } 5067 } 5068 closedir(dir); 5069 return result; 5070 } 5071 5072 // This code originates from JDK's sysOpen and open64_w 5073 // from src/solaris/hpi/src/system_md.c 5074 5075 int os::open(const char *path, int oflag, int mode) { 5076 if (strlen(path) > MAX_PATH - 1) { 5077 errno = ENAMETOOLONG; 5078 return -1; 5079 } 5080 5081 // All file descriptors that are opened in the Java process and not 5082 // specifically destined for a subprocess should have the close-on-exec 5083 // flag set. If we don't set it, then careless 3rd party native code 5084 // might fork and exec without closing all appropriate file descriptors 5085 // (e.g. as we do in closeDescriptors in UNIXProcess.c), and this in 5086 // turn might: 5087 // 5088 // - cause end-of-file to fail to be detected on some file 5089 // descriptors, resulting in mysterious hangs, or 5090 // 5091 // - might cause an fopen in the subprocess to fail on a system 5092 // suffering from bug 1085341. 5093 // 5094 // (Yes, the default setting of the close-on-exec flag is a Unix 5095 // design flaw) 5096 // 5097 // See: 5098 // 1085341: 32-bit stdio routines should support file descriptors >255 5099 // 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5100 // 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5101 // 5102 // Modern Linux kernels (after 2.6.23 2007) support O_CLOEXEC with open(). 5103 // O_CLOEXEC is preferable to using FD_CLOEXEC on an open file descriptor 5104 // because it saves a system call and removes a small window where the flag 5105 // is unset. On ancient Linux kernels the O_CLOEXEC flag will be ignored 5106 // and we fall back to using FD_CLOEXEC (see below). 5107 #ifdef O_CLOEXEC 5108 oflag |= O_CLOEXEC; 5109 #endif 5110 5111 int fd = ::open64(path, oflag, mode); 5112 if (fd == -1) return -1; 5113 5114 //If the open succeeded, the file might still be a directory 5115 { 5116 struct stat64 buf64; 5117 int ret = ::fstat64(fd, &buf64); 5118 int st_mode = buf64.st_mode; 5119 5120 if (ret != -1) { 5121 if ((st_mode & S_IFMT) == S_IFDIR) { 5122 errno = EISDIR; 5123 ::close(fd); 5124 return -1; 5125 } 5126 } else { 5127 ::close(fd); 5128 return -1; 5129 } 5130 } 5131 5132 #ifdef FD_CLOEXEC 5133 // Validate that the use of the O_CLOEXEC flag on open above worked. 5134 // With recent kernels, we will perform this check exactly once. 5135 static sig_atomic_t O_CLOEXEC_is_known_to_work = 0; 5136 if (!O_CLOEXEC_is_known_to_work) { 5137 int flags = ::fcntl(fd, F_GETFD); 5138 if (flags != -1) { 5139 if ((flags & FD_CLOEXEC) != 0) 5140 O_CLOEXEC_is_known_to_work = 1; 5141 else 5142 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5143 } 5144 } 5145 #endif 5146 5147 return fd; 5148 } 5149 5150 5151 // create binary file, rewriting existing file if required 5152 int os::create_binary_file(const char* path, bool rewrite_existing) { 5153 int oflags = O_WRONLY | O_CREAT; 5154 if (!rewrite_existing) { 5155 oflags |= O_EXCL; 5156 } 5157 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5158 } 5159 5160 // return current position of file pointer 5161 jlong os::current_file_offset(int fd) { 5162 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5163 } 5164 5165 // move file pointer to the specified offset 5166 jlong os::seek_to_file_offset(int fd, jlong offset) { 5167 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5168 } 5169 5170 // This code originates from JDK's sysAvailable 5171 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5172 5173 int os::available(int fd, jlong *bytes) { 5174 jlong cur, end; 5175 int mode; 5176 struct stat64 buf64; 5177 5178 if (::fstat64(fd, &buf64) >= 0) { 5179 mode = buf64.st_mode; 5180 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5181 // XXX: is the following call interruptible? If so, this might 5182 // need to go through the INTERRUPT_IO() wrapper as for other 5183 // blocking, interruptible calls in this file. 5184 int n; 5185 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5186 *bytes = n; 5187 return 1; 5188 } 5189 } 5190 } 5191 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5192 return 0; 5193 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5194 return 0; 5195 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5196 return 0; 5197 } 5198 *bytes = end - cur; 5199 return 1; 5200 } 5201 5202 // Map a block of memory. 5203 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5204 char *addr, size_t bytes, bool read_only, 5205 bool allow_exec) { 5206 int prot; 5207 int flags = MAP_PRIVATE; 5208 5209 if (read_only) { 5210 prot = PROT_READ; 5211 } else { 5212 prot = PROT_READ | PROT_WRITE; 5213 } 5214 5215 if (allow_exec) { 5216 prot |= PROT_EXEC; 5217 } 5218 5219 if (addr != NULL) { 5220 flags |= MAP_FIXED; 5221 } 5222 5223 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5224 fd, file_offset); 5225 if (mapped_address == MAP_FAILED) { 5226 return NULL; 5227 } 5228 return mapped_address; 5229 } 5230 5231 5232 // Remap a block of memory. 5233 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5234 char *addr, size_t bytes, bool read_only, 5235 bool allow_exec) { 5236 // same as map_memory() on this OS 5237 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5238 allow_exec); 5239 } 5240 5241 5242 // Unmap a block of memory. 5243 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5244 return munmap(addr, bytes) == 0; 5245 } 5246 5247 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5248 5249 static clockid_t thread_cpu_clockid(Thread* thread) { 5250 pthread_t tid = thread->osthread()->pthread_id(); 5251 clockid_t clockid; 5252 5253 // Get thread clockid 5254 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5255 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5256 return clockid; 5257 } 5258 5259 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5260 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5261 // of a thread. 5262 // 5263 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5264 // the fast estimate available on the platform. 5265 5266 jlong os::current_thread_cpu_time() { 5267 if (os::Linux::supports_fast_thread_cpu_time()) { 5268 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5269 } else { 5270 // return user + sys since the cost is the same 5271 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5272 } 5273 } 5274 5275 jlong os::thread_cpu_time(Thread* thread) { 5276 // consistent with what current_thread_cpu_time() returns 5277 if (os::Linux::supports_fast_thread_cpu_time()) { 5278 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5279 } else { 5280 return slow_thread_cpu_time(thread, true /* user + sys */); 5281 } 5282 } 5283 5284 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5285 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5286 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5287 } else { 5288 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5289 } 5290 } 5291 5292 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5293 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5294 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5295 } else { 5296 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5297 } 5298 } 5299 5300 // -1 on error. 5301 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5302 pid_t tid = thread->osthread()->thread_id(); 5303 char *s; 5304 char stat[2048]; 5305 int statlen; 5306 char proc_name[64]; 5307 int count; 5308 long sys_time, user_time; 5309 char cdummy; 5310 int idummy; 5311 long ldummy; 5312 FILE *fp; 5313 5314 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid); 5315 fp = fopen(proc_name, "r"); 5316 if (fp == NULL) return -1; 5317 statlen = fread(stat, 1, 2047, fp); 5318 stat[statlen] = '\0'; 5319 fclose(fp); 5320 5321 // Skip pid and the command string. Note that we could be dealing with 5322 // weird command names, e.g. user could decide to rename java launcher 5323 // to "java 1.4.2 :)", then the stat file would look like 5324 // 1234 (java 1.4.2 :)) R ... ... 5325 // We don't really need to know the command string, just find the last 5326 // occurrence of ")" and then start parsing from there. See bug 4726580. 5327 s = strrchr(stat, ')'); 5328 if (s == NULL) return -1; 5329 5330 // Skip blank chars 5331 do { s++; } while (s && isspace(*s)); 5332 5333 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5334 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5335 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5336 &user_time, &sys_time); 5337 if (count != 13) return -1; 5338 if (user_sys_cpu_time) { 5339 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5340 } else { 5341 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5342 } 5343 } 5344 5345 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5346 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5347 info_ptr->may_skip_backward = false; // elapsed time not wall time 5348 info_ptr->may_skip_forward = false; // elapsed time not wall time 5349 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5350 } 5351 5352 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5353 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5354 info_ptr->may_skip_backward = false; // elapsed time not wall time 5355 info_ptr->may_skip_forward = false; // elapsed time not wall time 5356 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5357 } 5358 5359 bool os::is_thread_cpu_time_supported() { 5360 return true; 5361 } 5362 5363 // System loadavg support. Returns -1 if load average cannot be obtained. 5364 // Linux doesn't yet have a (official) notion of processor sets, 5365 // so just return the system wide load average. 5366 int os::loadavg(double loadavg[], int nelem) { 5367 return ::getloadavg(loadavg, nelem); 5368 } 5369 5370 void os::pause() { 5371 char filename[MAX_PATH]; 5372 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5373 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5374 } else { 5375 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5376 } 5377 5378 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5379 if (fd != -1) { 5380 struct stat buf; 5381 ::close(fd); 5382 while (::stat(filename, &buf) == 0) { 5383 (void)::poll(NULL, 0, 100); 5384 } 5385 } else { 5386 jio_fprintf(stderr, 5387 "Could not open pause file '%s', continuing immediately.\n", filename); 5388 } 5389 } 5390 5391 5392 // Refer to the comments in os_solaris.cpp park-unpark. The next two 5393 // comment paragraphs are worth repeating here: 5394 // 5395 // Assumption: 5396 // Only one parker can exist on an event, which is why we allocate 5397 // them per-thread. Multiple unparkers can coexist. 5398 // 5399 // _Event serves as a restricted-range semaphore. 5400 // -1 : thread is blocked, i.e. there is a waiter 5401 // 0 : neutral: thread is running or ready, 5402 // could have been signaled after a wait started 5403 // 1 : signaled - thread is running or ready 5404 // 5405 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5406 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5407 // For specifics regarding the bug see GLIBC BUGID 261237 : 5408 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5409 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5410 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5411 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5412 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5413 // and monitorenter when we're using 1-0 locking. All those operations may result in 5414 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5415 // of libpthread avoids the problem, but isn't practical. 5416 // 5417 // Possible remedies: 5418 // 5419 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5420 // This is palliative and probabilistic, however. If the thread is preempted 5421 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5422 // than the minimum period may have passed, and the abstime may be stale (in the 5423 // past) resultin in a hang. Using this technique reduces the odds of a hang 5424 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5425 // 5426 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5427 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5428 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5429 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5430 // thread. 5431 // 5432 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5433 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5434 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5435 // This also works well. In fact it avoids kernel-level scalability impediments 5436 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5437 // timers in a graceful fashion. 5438 // 5439 // 4. When the abstime value is in the past it appears that control returns 5440 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5441 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5442 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5443 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5444 // It may be possible to avoid reinitialization by checking the return 5445 // value from pthread_cond_timedwait(). In addition to reinitializing the 5446 // condvar we must establish the invariant that cond_signal() is only called 5447 // within critical sections protected by the adjunct mutex. This prevents 5448 // cond_signal() from "seeing" a condvar that's in the midst of being 5449 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5450 // desirable signal-after-unlock optimization that avoids futile context switching. 5451 // 5452 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5453 // structure when a condvar is used or initialized. cond_destroy() would 5454 // release the helper structure. Our reinitialize-after-timedwait fix 5455 // put excessive stress on malloc/free and locks protecting the c-heap. 5456 // 5457 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5458 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5459 // and only enabling the work-around for vulnerable environments. 5460 5461 // utility to compute the abstime argument to timedwait: 5462 // millis is the relative timeout time 5463 // abstime will be the absolute timeout time 5464 // TODO: replace compute_abstime() with unpackTime() 5465 5466 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5467 if (millis < 0) millis = 0; 5468 5469 jlong seconds = millis / 1000; 5470 millis %= 1000; 5471 if (seconds > 50000000) { // see man cond_timedwait(3T) 5472 seconds = 50000000; 5473 } 5474 5475 if (os::supports_monotonic_clock()) { 5476 struct timespec now; 5477 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5478 assert_status(status == 0, status, "clock_gettime"); 5479 abstime->tv_sec = now.tv_sec + seconds; 5480 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5481 if (nanos >= NANOSECS_PER_SEC) { 5482 abstime->tv_sec += 1; 5483 nanos -= NANOSECS_PER_SEC; 5484 } 5485 abstime->tv_nsec = nanos; 5486 } else { 5487 struct timeval now; 5488 int status = gettimeofday(&now, NULL); 5489 assert(status == 0, "gettimeofday"); 5490 abstime->tv_sec = now.tv_sec + seconds; 5491 long usec = now.tv_usec + millis * 1000; 5492 if (usec >= 1000000) { 5493 abstime->tv_sec += 1; 5494 usec -= 1000000; 5495 } 5496 abstime->tv_nsec = usec * 1000; 5497 } 5498 return abstime; 5499 } 5500 5501 void os::PlatformEvent::park() { // AKA "down()" 5502 // Transitions for _Event: 5503 // -1 => -1 : illegal 5504 // 1 => 0 : pass - return immediately 5505 // 0 => -1 : block; then set _Event to 0 before returning 5506 5507 // Invariant: Only the thread associated with the Event/PlatformEvent 5508 // may call park(). 5509 // TODO: assert that _Assoc != NULL or _Assoc == Self 5510 assert(_nParked == 0, "invariant"); 5511 5512 int v; 5513 for (;;) { 5514 v = _Event; 5515 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5516 } 5517 guarantee(v >= 0, "invariant"); 5518 if (v == 0) { 5519 // Do this the hard way by blocking ... 5520 int status = pthread_mutex_lock(_mutex); 5521 assert_status(status == 0, status, "mutex_lock"); 5522 guarantee(_nParked == 0, "invariant"); 5523 ++_nParked; 5524 while (_Event < 0) { 5525 status = pthread_cond_wait(_cond, _mutex); 5526 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5527 // Treat this the same as if the wait was interrupted 5528 if (status == ETIME) { status = EINTR; } 5529 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5530 } 5531 --_nParked; 5532 5533 _Event = 0; 5534 status = pthread_mutex_unlock(_mutex); 5535 assert_status(status == 0, status, "mutex_unlock"); 5536 // Paranoia to ensure our locked and lock-free paths interact 5537 // correctly with each other. 5538 OrderAccess::fence(); 5539 } 5540 guarantee(_Event >= 0, "invariant"); 5541 } 5542 5543 int os::PlatformEvent::park(jlong millis) { 5544 // Transitions for _Event: 5545 // -1 => -1 : illegal 5546 // 1 => 0 : pass - return immediately 5547 // 0 => -1 : block; then set _Event to 0 before returning 5548 5549 guarantee(_nParked == 0, "invariant"); 5550 5551 int v; 5552 for (;;) { 5553 v = _Event; 5554 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5555 } 5556 guarantee(v >= 0, "invariant"); 5557 if (v != 0) return OS_OK; 5558 5559 // We do this the hard way, by blocking the thread. 5560 // Consider enforcing a minimum timeout value. 5561 struct timespec abst; 5562 compute_abstime(&abst, millis); 5563 5564 int ret = OS_TIMEOUT; 5565 int status = pthread_mutex_lock(_mutex); 5566 assert_status(status == 0, status, "mutex_lock"); 5567 guarantee(_nParked == 0, "invariant"); 5568 ++_nParked; 5569 5570 // Object.wait(timo) will return because of 5571 // (a) notification 5572 // (b) timeout 5573 // (c) thread.interrupt 5574 // 5575 // Thread.interrupt and object.notify{All} both call Event::set. 5576 // That is, we treat thread.interrupt as a special case of notification. 5577 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false. 5578 // We assume all ETIME returns are valid. 5579 // 5580 // TODO: properly differentiate simultaneous notify+interrupt. 5581 // In that case, we should propagate the notify to another waiter. 5582 5583 while (_Event < 0) { 5584 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5585 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5586 pthread_cond_destroy(_cond); 5587 pthread_cond_init(_cond, os::Linux::condAttr()); 5588 } 5589 assert_status(status == 0 || status == EINTR || 5590 status == ETIME || status == ETIMEDOUT, 5591 status, "cond_timedwait"); 5592 if (!FilterSpuriousWakeups) break; // previous semantics 5593 if (status == ETIME || status == ETIMEDOUT) break; 5594 // We consume and ignore EINTR and spurious wakeups. 5595 } 5596 --_nParked; 5597 if (_Event >= 0) { 5598 ret = OS_OK; 5599 } 5600 _Event = 0; 5601 status = pthread_mutex_unlock(_mutex); 5602 assert_status(status == 0, status, "mutex_unlock"); 5603 assert(_nParked == 0, "invariant"); 5604 // Paranoia to ensure our locked and lock-free paths interact 5605 // correctly with each other. 5606 OrderAccess::fence(); 5607 return ret; 5608 } 5609 5610 void os::PlatformEvent::unpark() { 5611 // Transitions for _Event: 5612 // 0 => 1 : just return 5613 // 1 => 1 : just return 5614 // -1 => either 0 or 1; must signal target thread 5615 // That is, we can safely transition _Event from -1 to either 5616 // 0 or 1. 5617 // See also: "Semaphores in Plan 9" by Mullender & Cox 5618 // 5619 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5620 // that it will take two back-to-back park() calls for the owning 5621 // thread to block. This has the benefit of forcing a spurious return 5622 // from the first park() call after an unpark() call which will help 5623 // shake out uses of park() and unpark() without condition variables. 5624 5625 if (Atomic::xchg(1, &_Event) >= 0) return; 5626 5627 // Wait for the thread associated with the event to vacate 5628 int status = pthread_mutex_lock(_mutex); 5629 assert_status(status == 0, status, "mutex_lock"); 5630 int AnyWaiters = _nParked; 5631 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5632 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5633 AnyWaiters = 0; 5634 pthread_cond_signal(_cond); 5635 } 5636 status = pthread_mutex_unlock(_mutex); 5637 assert_status(status == 0, status, "mutex_unlock"); 5638 if (AnyWaiters != 0) { 5639 // Note that we signal() *after* dropping the lock for "immortal" Events. 5640 // This is safe and avoids a common class of futile wakeups. In rare 5641 // circumstances this can cause a thread to return prematurely from 5642 // cond_{timed}wait() but the spurious wakeup is benign and the victim 5643 // will simply re-test the condition and re-park itself. 5644 // This provides particular benefit if the underlying platform does not 5645 // provide wait morphing. 5646 status = pthread_cond_signal(_cond); 5647 assert_status(status == 0, status, "cond_signal"); 5648 } 5649 } 5650 5651 5652 // JSR166 5653 // ------------------------------------------------------- 5654 5655 // The solaris and linux implementations of park/unpark are fairly 5656 // conservative for now, but can be improved. They currently use a 5657 // mutex/condvar pair, plus a a count. 5658 // Park decrements count if > 0, else does a condvar wait. Unpark 5659 // sets count to 1 and signals condvar. Only one thread ever waits 5660 // on the condvar. Contention seen when trying to park implies that someone 5661 // is unparking you, so don't wait. And spurious returns are fine, so there 5662 // is no need to track notifications. 5663 5664 // This code is common to linux and solaris and will be moved to a 5665 // common place in dolphin. 5666 // 5667 // The passed in time value is either a relative time in nanoseconds 5668 // or an absolute time in milliseconds. Either way it has to be unpacked 5669 // into suitable seconds and nanoseconds components and stored in the 5670 // given timespec structure. 5671 // Given time is a 64-bit value and the time_t used in the timespec is only 5672 // a signed-32-bit value (except on 64-bit Linux) we have to watch for 5673 // overflow if times way in the future are given. Further on Solaris versions 5674 // prior to 10 there is a restriction (see cond_timedwait) that the specified 5675 // number of seconds, in abstime, is less than current_time + 100,000,000. 5676 // As it will be 28 years before "now + 100000000" will overflow we can 5677 // ignore overflow and just impose a hard-limit on seconds using the value 5678 // of "now + 100,000,000". This places a limit on the timeout of about 3.17 5679 // years from "now". 5680 5681 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5682 assert(time > 0, "convertTime"); 5683 time_t max_secs = 0; 5684 5685 if (!os::supports_monotonic_clock() || isAbsolute) { 5686 struct timeval now; 5687 int status = gettimeofday(&now, NULL); 5688 assert(status == 0, "gettimeofday"); 5689 5690 max_secs = now.tv_sec + MAX_SECS; 5691 5692 if (isAbsolute) { 5693 jlong secs = time / 1000; 5694 if (secs > max_secs) { 5695 absTime->tv_sec = max_secs; 5696 } else { 5697 absTime->tv_sec = secs; 5698 } 5699 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5700 } else { 5701 jlong secs = time / NANOSECS_PER_SEC; 5702 if (secs >= MAX_SECS) { 5703 absTime->tv_sec = max_secs; 5704 absTime->tv_nsec = 0; 5705 } else { 5706 absTime->tv_sec = now.tv_sec + secs; 5707 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5708 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5709 absTime->tv_nsec -= NANOSECS_PER_SEC; 5710 ++absTime->tv_sec; // note: this must be <= max_secs 5711 } 5712 } 5713 } 5714 } else { 5715 // must be relative using monotonic clock 5716 struct timespec now; 5717 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5718 assert_status(status == 0, status, "clock_gettime"); 5719 max_secs = now.tv_sec + MAX_SECS; 5720 jlong secs = time / NANOSECS_PER_SEC; 5721 if (secs >= MAX_SECS) { 5722 absTime->tv_sec = max_secs; 5723 absTime->tv_nsec = 0; 5724 } else { 5725 absTime->tv_sec = now.tv_sec + secs; 5726 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5727 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5728 absTime->tv_nsec -= NANOSECS_PER_SEC; 5729 ++absTime->tv_sec; // note: this must be <= max_secs 5730 } 5731 } 5732 } 5733 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5734 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5735 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5736 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5737 } 5738 5739 void Parker::park(bool isAbsolute, jlong time) { 5740 // Ideally we'd do something useful while spinning, such 5741 // as calling unpackTime(). 5742 5743 // Optional fast-path check: 5744 // Return immediately if a permit is available. 5745 // We depend on Atomic::xchg() having full barrier semantics 5746 // since we are doing a lock-free update to _counter. 5747 if (Atomic::xchg(0, &_counter) > 0) return; 5748 5749 Thread* thread = Thread::current(); 5750 assert(thread->is_Java_thread(), "Must be JavaThread"); 5751 JavaThread *jt = (JavaThread *)thread; 5752 5753 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5754 // Check interrupt before trying to wait 5755 if (Thread::is_interrupted(thread, false)) { 5756 return; 5757 } 5758 5759 // Next, demultiplex/decode time arguments 5760 timespec absTime; 5761 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all 5762 return; 5763 } 5764 if (time > 0) { 5765 unpackTime(&absTime, isAbsolute, time); 5766 } 5767 5768 5769 // Enter safepoint region 5770 // Beware of deadlocks such as 6317397. 5771 // The per-thread Parker:: mutex is a classic leaf-lock. 5772 // In particular a thread must never block on the Threads_lock while 5773 // holding the Parker:: mutex. If safepoints are pending both the 5774 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5775 ThreadBlockInVM tbivm(jt); 5776 5777 // Don't wait if cannot get lock since interference arises from 5778 // unblocking. Also. check interrupt before trying wait 5779 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5780 return; 5781 } 5782 5783 int status; 5784 if (_counter > 0) { // no wait needed 5785 _counter = 0; 5786 status = pthread_mutex_unlock(_mutex); 5787 assert(status == 0, "invariant"); 5788 // Paranoia to ensure our locked and lock-free paths interact 5789 // correctly with each other and Java-level accesses. 5790 OrderAccess::fence(); 5791 return; 5792 } 5793 5794 #ifdef ASSERT 5795 // Don't catch signals while blocked; let the running threads have the signals. 5796 // (This allows a debugger to break into the running thread.) 5797 sigset_t oldsigs; 5798 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5799 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5800 #endif 5801 5802 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5803 jt->set_suspend_equivalent(); 5804 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5805 5806 assert(_cur_index == -1, "invariant"); 5807 if (time == 0) { 5808 _cur_index = REL_INDEX; // arbitrary choice when not timed 5809 status = pthread_cond_wait(&_cond[_cur_index], _mutex); 5810 } else { 5811 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5812 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime); 5813 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5814 pthread_cond_destroy(&_cond[_cur_index]); 5815 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5816 } 5817 } 5818 _cur_index = -1; 5819 assert_status(status == 0 || status == EINTR || 5820 status == ETIME || status == ETIMEDOUT, 5821 status, "cond_timedwait"); 5822 5823 #ifdef ASSERT 5824 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5825 #endif 5826 5827 _counter = 0; 5828 status = pthread_mutex_unlock(_mutex); 5829 assert_status(status == 0, status, "invariant"); 5830 // Paranoia to ensure our locked and lock-free paths interact 5831 // correctly with each other and Java-level accesses. 5832 OrderAccess::fence(); 5833 5834 // If externally suspended while waiting, re-suspend 5835 if (jt->handle_special_suspend_equivalent_condition()) { 5836 jt->java_suspend_self(); 5837 } 5838 } 5839 5840 void Parker::unpark() { 5841 int status = pthread_mutex_lock(_mutex); 5842 assert(status == 0, "invariant"); 5843 const int s = _counter; 5844 _counter = 1; 5845 if (s < 1) { 5846 // thread might be parked 5847 if (_cur_index != -1) { 5848 // thread is definitely parked 5849 if (WorkAroundNPTLTimedWaitHang) { 5850 status = pthread_cond_signal(&_cond[_cur_index]); 5851 assert(status == 0, "invariant"); 5852 status = pthread_mutex_unlock(_mutex); 5853 assert(status == 0, "invariant"); 5854 } else { 5855 status = pthread_mutex_unlock(_mutex); 5856 assert(status == 0, "invariant"); 5857 status = pthread_cond_signal(&_cond[_cur_index]); 5858 assert(status == 0, "invariant"); 5859 } 5860 } else { 5861 pthread_mutex_unlock(_mutex); 5862 assert(status == 0, "invariant"); 5863 } 5864 } else { 5865 pthread_mutex_unlock(_mutex); 5866 assert(status == 0, "invariant"); 5867 } 5868 } 5869 5870 5871 extern char** environ; 5872 5873 #ifndef __NR_fork 5874 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 5875 #endif 5876 5877 #ifndef __NR_execve 5878 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 5879 #endif 5880 5881 // Run the specified command in a separate process. Return its exit value, 5882 // or -1 on failure (e.g. can't fork a new process). 5883 // Unlike system(), this function can be called from signal handler. It 5884 // doesn't block SIGINT et al. 5885 int os::fork_and_exec(char* cmd) { 5886 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5887 5888 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5889 // pthread_atfork handlers and reset pthread library. All we need is a 5890 // separate process to execve. Make a direct syscall to fork process. 5891 // On IA64 there's no fork syscall, we have to use fork() and hope for 5892 // the best... 5893 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5894 IA64_ONLY(fork();) 5895 5896 if (pid < 0) { 5897 // fork failed 5898 return -1; 5899 5900 } else if (pid == 0) { 5901 // child process 5902 5903 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5904 // first to kill every thread on the thread list. Because this list is 5905 // not reset by fork() (see notes above), execve() will instead kill 5906 // every thread in the parent process. We know this is the only thread 5907 // in the new process, so make a system call directly. 5908 // IA64 should use normal execve() from glibc to match the glibc fork() 5909 // above. 5910 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5911 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5912 5913 // execve failed 5914 _exit(-1); 5915 5916 } else { 5917 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5918 // care about the actual exit code, for now. 5919 5920 int status; 5921 5922 // Wait for the child process to exit. This returns immediately if 5923 // the child has already exited. */ 5924 while (waitpid(pid, &status, 0) < 0) { 5925 switch (errno) { 5926 case ECHILD: return 0; 5927 case EINTR: break; 5928 default: return -1; 5929 } 5930 } 5931 5932 if (WIFEXITED(status)) { 5933 // The child exited normally; get its exit code. 5934 return WEXITSTATUS(status); 5935 } else if (WIFSIGNALED(status)) { 5936 // The child exited because of a signal 5937 // The best value to return is 0x80 + signal number, 5938 // because that is what all Unix shells do, and because 5939 // it allows callers to distinguish between process exit and 5940 // process death by signal. 5941 return 0x80 + WTERMSIG(status); 5942 } else { 5943 // Unknown exit code; pass it through 5944 return status; 5945 } 5946 } 5947 } 5948 5949 // is_headless_jre() 5950 // 5951 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 5952 // in order to report if we are running in a headless jre 5953 // 5954 // Since JDK8 xawt/libmawt.so was moved into the same directory 5955 // as libawt.so, and renamed libawt_xawt.so 5956 // 5957 bool os::is_headless_jre() { 5958 struct stat statbuf; 5959 char buf[MAXPATHLEN]; 5960 char libmawtpath[MAXPATHLEN]; 5961 const char *xawtstr = "/xawt/libmawt.so"; 5962 const char *new_xawtstr = "/libawt_xawt.so"; 5963 char *p; 5964 5965 // Get path to libjvm.so 5966 os::jvm_path(buf, sizeof(buf)); 5967 5968 // Get rid of libjvm.so 5969 p = strrchr(buf, '/'); 5970 if (p == NULL) { 5971 return false; 5972 } else { 5973 *p = '\0'; 5974 } 5975 5976 // Get rid of client or server 5977 p = strrchr(buf, '/'); 5978 if (p == NULL) { 5979 return false; 5980 } else { 5981 *p = '\0'; 5982 } 5983 5984 // check xawt/libmawt.so 5985 strcpy(libmawtpath, buf); 5986 strcat(libmawtpath, xawtstr); 5987 if (::stat(libmawtpath, &statbuf) == 0) return false; 5988 5989 // check libawt_xawt.so 5990 strcpy(libmawtpath, buf); 5991 strcat(libmawtpath, new_xawtstr); 5992 if (::stat(libmawtpath, &statbuf) == 0) return false; 5993 5994 return true; 5995 } 5996 5997 // Get the default path to the core file 5998 // Returns the length of the string 5999 int os::get_core_path(char* buffer, size_t bufferSize) { 6000 /* 6001 * Max length of /proc/sys/kernel/core_pattern is 128 characters. 6002 * See https://www.kernel.org/doc/Documentation/sysctl/kernel.txt 6003 */ 6004 const int core_pattern_len = 129; 6005 char core_pattern[core_pattern_len] = {0}; 6006 6007 int core_pattern_file = ::open("/proc/sys/kernel/core_pattern", O_RDONLY); 6008 if (core_pattern_file != -1) { 6009 ssize_t ret = ::read(core_pattern_file, core_pattern, core_pattern_len); 6010 ::close(core_pattern_file); 6011 6012 if (ret > 0) { 6013 char *last_char = core_pattern + strlen(core_pattern) - 1; 6014 6015 if (*last_char == '\n') { 6016 *last_char = '\0'; 6017 } 6018 } 6019 } 6020 6021 if (strlen(core_pattern) == 0) { 6022 return 0; 6023 } 6024 6025 char *pid_pos = strstr(core_pattern, "%p"); 6026 size_t written; 6027 6028 if (core_pattern[0] == '/') { 6029 written = jio_snprintf(buffer, bufferSize, core_pattern); 6030 } else { 6031 char cwd[PATH_MAX]; 6032 6033 const char* p = get_current_directory(cwd, PATH_MAX); 6034 if (p == NULL) { 6035 assert(p != NULL, "failed to get current directory"); 6036 return 0; 6037 } 6038 6039 if (core_pattern[0] == '|') { 6040 written = jio_snprintf(buffer, bufferSize, 6041 "\"%s\" (or dumping to %s/core.%d)", 6042 &core_pattern[1], p, current_process_id()); 6043 } else { 6044 written = jio_snprintf(buffer, bufferSize, "%s/%s", p, core_pattern); 6045 } 6046 } 6047 6048 if ((written >= 0) && (written < bufferSize) 6049 && (pid_pos == NULL) && (core_pattern[0] != '|')) { 6050 int core_uses_pid_file = ::open("/proc/sys/kernel/core_uses_pid", O_RDONLY); 6051 6052 if (core_uses_pid_file != -1) { 6053 char core_uses_pid = 0; 6054 ssize_t ret = ::read(core_uses_pid_file, &core_uses_pid, 1); 6055 ::close(core_uses_pid_file); 6056 6057 if (core_uses_pid == '1'){ 6058 jio_snprintf(buffer + written, bufferSize - written, 6059 ".%d", current_process_id()); 6060 } 6061 } 6062 } 6063 6064 return strlen(buffer); 6065 } 6066 6067 /////////////// Unit tests /////////////// 6068 6069 #ifndef PRODUCT 6070 6071 #define test_log(...) \ 6072 do { \ 6073 if (VerboseInternalVMTests) { \ 6074 tty->print_cr(__VA_ARGS__); \ 6075 tty->flush(); \ 6076 } \ 6077 } while (false) 6078 6079 class TestReserveMemorySpecial : AllStatic { 6080 public: 6081 static void small_page_write(void* addr, size_t size) { 6082 size_t page_size = os::vm_page_size(); 6083 6084 char* end = (char*)addr + size; 6085 for (char* p = (char*)addr; p < end; p += page_size) { 6086 *p = 1; 6087 } 6088 } 6089 6090 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6091 if (!UseHugeTLBFS) { 6092 return; 6093 } 6094 6095 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6096 6097 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6098 6099 if (addr != NULL) { 6100 small_page_write(addr, size); 6101 6102 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6103 } 6104 } 6105 6106 static void test_reserve_memory_special_huge_tlbfs_only() { 6107 if (!UseHugeTLBFS) { 6108 return; 6109 } 6110 6111 size_t lp = os::large_page_size(); 6112 6113 for (size_t size = lp; size <= lp * 10; size += lp) { 6114 test_reserve_memory_special_huge_tlbfs_only(size); 6115 } 6116 } 6117 6118 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) { 6119 if (!UseHugeTLBFS) { 6120 return; 6121 } 6122 6123 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")", 6124 size, alignment); 6125 6126 assert(size >= os::large_page_size(), "Incorrect input to test"); 6127 6128 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6129 6130 if (addr != NULL) { 6131 small_page_write(addr, size); 6132 6133 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6134 } 6135 } 6136 6137 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) { 6138 size_t lp = os::large_page_size(); 6139 size_t ag = os::vm_allocation_granularity(); 6140 6141 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6142 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment); 6143 } 6144 } 6145 6146 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6147 size_t lp = os::large_page_size(); 6148 size_t ag = os::vm_allocation_granularity(); 6149 6150 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp); 6151 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag); 6152 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2); 6153 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2); 6154 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag); 6155 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag); 6156 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2); 6157 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10); 6158 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2); 6159 } 6160 6161 static void test_reserve_memory_special_huge_tlbfs() { 6162 if (!UseHugeTLBFS) { 6163 return; 6164 } 6165 6166 test_reserve_memory_special_huge_tlbfs_only(); 6167 test_reserve_memory_special_huge_tlbfs_mixed(); 6168 } 6169 6170 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6171 if (!UseSHM) { 6172 return; 6173 } 6174 6175 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6176 6177 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6178 6179 if (addr != NULL) { 6180 assert(is_ptr_aligned(addr, alignment), "Check"); 6181 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6182 6183 small_page_write(addr, size); 6184 6185 os::Linux::release_memory_special_shm(addr, size); 6186 } 6187 } 6188 6189 static void test_reserve_memory_special_shm() { 6190 size_t lp = os::large_page_size(); 6191 size_t ag = os::vm_allocation_granularity(); 6192 6193 for (size_t size = ag; size < lp * 3; size += ag) { 6194 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6195 test_reserve_memory_special_shm(size, alignment); 6196 } 6197 } 6198 } 6199 6200 static void test() { 6201 test_reserve_memory_special_huge_tlbfs(); 6202 test_reserve_memory_special_shm(); 6203 } 6204 }; 6205 6206 void TestReserveMemorySpecial_test() { 6207 TestReserveMemorySpecial::test(); 6208 } 6209 6210 #endif