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 #elif defined(AARCH64) 251 static char cpu_arch[] = "aarch64"; 252 #else 253 #error Add appropriate cpu_arch setting 254 #endif 255 256 257 // pid_t gettid() 258 // 259 // Returns the kernel thread id of the currently running thread. Kernel 260 // thread id is used to access /proc. 261 // 262 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 263 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 264 // 265 pid_t os::Linux::gettid() { 266 int rslt = syscall(SYS_gettid); 267 if (rslt == -1) { 268 // old kernel, no NPTL support 269 return getpid(); 270 } else { 271 return (pid_t)rslt; 272 } 273 } 274 275 // Most versions of linux have a bug where the number of processors are 276 // determined by looking at the /proc file system. In a chroot environment, 277 // the system call returns 1. This causes the VM to act as if it is 278 // a single processor and elide locking (see is_MP() call). 279 static bool unsafe_chroot_detected = false; 280 static const char *unstable_chroot_error = "/proc file system not found.\n" 281 "Java may be unstable running multithreaded in a chroot " 282 "environment on Linux when /proc filesystem is not mounted."; 283 284 void os::Linux::initialize_system_info() { 285 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 286 if (processor_count() == 1) { 287 pid_t pid = os::Linux::gettid(); 288 char fname[32]; 289 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 290 FILE *fp = fopen(fname, "r"); 291 if (fp == NULL) { 292 unsafe_chroot_detected = true; 293 } else { 294 fclose(fp); 295 } 296 } 297 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 298 assert(processor_count() > 0, "linux error"); 299 } 300 301 void os::init_system_properties_values() { 302 // The next steps are taken in the product version: 303 // 304 // Obtain the JAVA_HOME value from the location of libjvm.so. 305 // This library should be located at: 306 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 307 // 308 // If "/jre/lib/" appears at the right place in the path, then we 309 // assume libjvm.so is installed in a JDK and we use this path. 310 // 311 // Otherwise exit with message: "Could not create the Java virtual machine." 312 // 313 // The following extra steps are taken in the debugging version: 314 // 315 // If "/jre/lib/" does NOT appear at the right place in the path 316 // instead of exit check for $JAVA_HOME environment variable. 317 // 318 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 319 // then we append a fake suffix "hotspot/libjvm.so" to this path so 320 // it looks like libjvm.so is installed there 321 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 322 // 323 // Otherwise exit. 324 // 325 // Important note: if the location of libjvm.so changes this 326 // code needs to be changed accordingly. 327 328 // See ld(1): 329 // The linker uses the following search paths to locate required 330 // shared libraries: 331 // 1: ... 332 // ... 333 // 7: The default directories, normally /lib and /usr/lib. 334 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 335 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 336 #else 337 #define DEFAULT_LIBPATH "/lib:/usr/lib" 338 #endif 339 340 // Base path of extensions installed on the system. 341 #define SYS_EXT_DIR "/usr/java/packages" 342 #define EXTENSIONS_DIR "/lib/ext" 343 344 // Buffer that fits several sprintfs. 345 // Note that the space for the colon and the trailing null are provided 346 // by the nulls included by the sizeof operator. 347 const size_t bufsize = 348 MAX2((size_t)MAXPATHLEN, // For dll_dir & friends. 349 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR)); // extensions dir 350 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 351 352 // sysclasspath, java_home, dll_dir 353 { 354 char *pslash; 355 os::jvm_path(buf, bufsize); 356 357 // Found the full path to libjvm.so. 358 // Now cut the path to <java_home>/jre if we can. 359 pslash = strrchr(buf, '/'); 360 if (pslash != NULL) { 361 *pslash = '\0'; // Get rid of /libjvm.so. 362 } 363 pslash = strrchr(buf, '/'); 364 if (pslash != NULL) { 365 *pslash = '\0'; // Get rid of /{client|server|hotspot}. 366 } 367 Arguments::set_dll_dir(buf); 368 369 if (pslash != NULL) { 370 pslash = strrchr(buf, '/'); 371 if (pslash != NULL) { 372 *pslash = '\0'; // Get rid of /<arch>. 373 pslash = strrchr(buf, '/'); 374 if (pslash != NULL) { 375 *pslash = '\0'; // Get rid of /lib. 376 } 377 } 378 } 379 Arguments::set_java_home(buf); 380 set_boot_path('/', ':'); 381 } 382 383 // Where to look for native libraries. 384 // 385 // Note: Due to a legacy implementation, most of the library path 386 // is set in the launcher. This was to accomodate linking restrictions 387 // on legacy Linux implementations (which are no longer supported). 388 // Eventually, all the library path setting will be done here. 389 // 390 // However, to prevent the proliferation of improperly built native 391 // libraries, the new path component /usr/java/packages is added here. 392 // Eventually, all the library path setting will be done here. 393 { 394 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It 395 // should always exist (until the legacy problem cited above is 396 // addressed). 397 const char *v = ::getenv("LD_LIBRARY_PATH"); 398 const char *v_colon = ":"; 399 if (v == NULL) { v = ""; v_colon = ""; } 400 // That's +1 for the colon and +1 for the trailing '\0'. 401 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char, 402 strlen(v) + 1 + 403 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1, 404 mtInternal); 405 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch); 406 Arguments::set_library_path(ld_library_path); 407 FREE_C_HEAP_ARRAY(char, ld_library_path); 408 } 409 410 // Extensions directories. 411 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home()); 412 Arguments::set_ext_dirs(buf); 413 414 FREE_C_HEAP_ARRAY(char, buf); 415 416 #undef DEFAULT_LIBPATH 417 #undef SYS_EXT_DIR 418 #undef EXTENSIONS_DIR 419 } 420 421 //////////////////////////////////////////////////////////////////////////////// 422 // breakpoint support 423 424 void os::breakpoint() { 425 BREAKPOINT; 426 } 427 428 extern "C" void breakpoint() { 429 // use debugger to set breakpoint here 430 } 431 432 //////////////////////////////////////////////////////////////////////////////// 433 // signal support 434 435 debug_only(static bool signal_sets_initialized = false); 436 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 437 438 bool os::Linux::is_sig_ignored(int sig) { 439 struct sigaction oact; 440 sigaction(sig, (struct sigaction*)NULL, &oact); 441 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 442 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 443 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) { 444 return true; 445 } else { 446 return false; 447 } 448 } 449 450 void os::Linux::signal_sets_init() { 451 // Should also have an assertion stating we are still single-threaded. 452 assert(!signal_sets_initialized, "Already initialized"); 453 // Fill in signals that are necessarily unblocked for all threads in 454 // the VM. Currently, we unblock the following signals: 455 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 456 // by -Xrs (=ReduceSignalUsage)); 457 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 458 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 459 // the dispositions or masks wrt these signals. 460 // Programs embedding the VM that want to use the above signals for their 461 // own purposes must, at this time, use the "-Xrs" option to prevent 462 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 463 // (See bug 4345157, and other related bugs). 464 // In reality, though, unblocking these signals is really a nop, since 465 // these signals are not blocked by default. 466 sigemptyset(&unblocked_sigs); 467 sigemptyset(&allowdebug_blocked_sigs); 468 sigaddset(&unblocked_sigs, SIGILL); 469 sigaddset(&unblocked_sigs, SIGSEGV); 470 sigaddset(&unblocked_sigs, SIGBUS); 471 sigaddset(&unblocked_sigs, SIGFPE); 472 #if defined(PPC64) 473 sigaddset(&unblocked_sigs, SIGTRAP); 474 #endif 475 sigaddset(&unblocked_sigs, SR_signum); 476 477 if (!ReduceSignalUsage) { 478 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 479 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 480 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 481 } 482 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 483 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 484 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 485 } 486 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 487 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 488 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 489 } 490 } 491 // Fill in signals that are blocked by all but the VM thread. 492 sigemptyset(&vm_sigs); 493 if (!ReduceSignalUsage) { 494 sigaddset(&vm_sigs, BREAK_SIGNAL); 495 } 496 debug_only(signal_sets_initialized = true); 497 498 } 499 500 // These are signals that are unblocked while a thread is running Java. 501 // (For some reason, they get blocked by default.) 502 sigset_t* os::Linux::unblocked_signals() { 503 assert(signal_sets_initialized, "Not initialized"); 504 return &unblocked_sigs; 505 } 506 507 // These are the signals that are blocked while a (non-VM) thread is 508 // running Java. Only the VM thread handles these signals. 509 sigset_t* os::Linux::vm_signals() { 510 assert(signal_sets_initialized, "Not initialized"); 511 return &vm_sigs; 512 } 513 514 // These are signals that are blocked during cond_wait to allow debugger in 515 sigset_t* os::Linux::allowdebug_blocked_signals() { 516 assert(signal_sets_initialized, "Not initialized"); 517 return &allowdebug_blocked_sigs; 518 } 519 520 void os::Linux::hotspot_sigmask(Thread* thread) { 521 522 //Save caller's signal mask before setting VM signal mask 523 sigset_t caller_sigmask; 524 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 525 526 OSThread* osthread = thread->osthread(); 527 osthread->set_caller_sigmask(caller_sigmask); 528 529 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 530 531 if (!ReduceSignalUsage) { 532 if (thread->is_VM_thread()) { 533 // Only the VM thread handles BREAK_SIGNAL ... 534 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 535 } else { 536 // ... all other threads block BREAK_SIGNAL 537 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 538 } 539 } 540 } 541 542 ////////////////////////////////////////////////////////////////////////////// 543 // detecting pthread library 544 545 void os::Linux::libpthread_init() { 546 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 547 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 548 // generic name for earlier versions. 549 // Define macros here so we can build HotSpot on old systems. 550 #ifndef _CS_GNU_LIBC_VERSION 551 #define _CS_GNU_LIBC_VERSION 2 552 #endif 553 #ifndef _CS_GNU_LIBPTHREAD_VERSION 554 #define _CS_GNU_LIBPTHREAD_VERSION 3 555 #endif 556 557 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 558 if (n > 0) { 559 char *str = (char *)malloc(n, mtInternal); 560 confstr(_CS_GNU_LIBC_VERSION, str, n); 561 os::Linux::set_glibc_version(str); 562 } else { 563 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 564 static char _gnu_libc_version[32]; 565 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 566 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 567 os::Linux::set_glibc_version(_gnu_libc_version); 568 } 569 570 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 571 if (n > 0) { 572 char *str = (char *)malloc(n, mtInternal); 573 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 574 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 575 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 576 // is the case. LinuxThreads has a hard limit on max number of threads. 577 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 578 // On the other hand, NPTL does not have such a limit, sysconf() 579 // will return -1 and errno is not changed. Check if it is really NPTL. 580 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 581 strstr(str, "NPTL") && 582 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 583 free(str); 584 os::Linux::set_libpthread_version("linuxthreads"); 585 } else { 586 os::Linux::set_libpthread_version(str); 587 } 588 } else { 589 // glibc before 2.3.2 only has LinuxThreads. 590 os::Linux::set_libpthread_version("linuxthreads"); 591 } 592 593 if (strstr(libpthread_version(), "NPTL")) { 594 os::Linux::set_is_NPTL(); 595 } else { 596 os::Linux::set_is_LinuxThreads(); 597 } 598 599 // LinuxThreads have two flavors: floating-stack mode, which allows variable 600 // stack size; and fixed-stack mode. NPTL is always floating-stack. 601 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 602 os::Linux::set_is_floating_stack(); 603 } 604 } 605 606 ///////////////////////////////////////////////////////////////////////////// 607 // thread stack 608 609 // Force Linux kernel to expand current thread stack. If "bottom" is close 610 // to the stack guard, caller should block all signals. 611 // 612 // MAP_GROWSDOWN: 613 // A special mmap() flag that is used to implement thread stacks. It tells 614 // kernel that the memory region should extend downwards when needed. This 615 // allows early versions of LinuxThreads to only mmap the first few pages 616 // when creating a new thread. Linux kernel will automatically expand thread 617 // stack as needed (on page faults). 618 // 619 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 620 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 621 // region, it's hard to tell if the fault is due to a legitimate stack 622 // access or because of reading/writing non-exist memory (e.g. buffer 623 // overrun). As a rule, if the fault happens below current stack pointer, 624 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 625 // application (see Linux kernel fault.c). 626 // 627 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 628 // stack overflow detection. 629 // 630 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 631 // not use this flag. However, the stack of initial thread is not created 632 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 633 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 634 // and then attach the thread to JVM. 635 // 636 // To get around the problem and allow stack banging on Linux, we need to 637 // manually expand thread stack after receiving the SIGSEGV. 638 // 639 // There are two ways to expand thread stack to address "bottom", we used 640 // both of them in JVM before 1.5: 641 // 1. adjust stack pointer first so that it is below "bottom", and then 642 // touch "bottom" 643 // 2. mmap() the page in question 644 // 645 // Now alternate signal stack is gone, it's harder to use 2. For instance, 646 // if current sp is already near the lower end of page 101, and we need to 647 // call mmap() to map page 100, it is possible that part of the mmap() frame 648 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 649 // That will destroy the mmap() frame and cause VM to crash. 650 // 651 // The following code works by adjusting sp first, then accessing the "bottom" 652 // page to force a page fault. Linux kernel will then automatically expand the 653 // stack mapping. 654 // 655 // _expand_stack_to() assumes its frame size is less than page size, which 656 // should always be true if the function is not inlined. 657 658 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 659 #define NOINLINE 660 #else 661 #define NOINLINE __attribute__ ((noinline)) 662 #endif 663 664 static void _expand_stack_to(address bottom) NOINLINE; 665 666 static void _expand_stack_to(address bottom) { 667 address sp; 668 size_t size; 669 volatile char *p; 670 671 // Adjust bottom to point to the largest address within the same page, it 672 // gives us a one-page buffer if alloca() allocates slightly more memory. 673 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 674 bottom += os::Linux::page_size() - 1; 675 676 // sp might be slightly above current stack pointer; if that's the case, we 677 // will alloca() a little more space than necessary, which is OK. Don't use 678 // os::current_stack_pointer(), as its result can be slightly below current 679 // stack pointer, causing us to not alloca enough to reach "bottom". 680 sp = (address)&sp; 681 682 if (sp > bottom) { 683 size = sp - bottom; 684 p = (volatile char *)alloca(size); 685 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 686 p[0] = '\0'; 687 } 688 } 689 690 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 691 assert(t!=NULL, "just checking"); 692 assert(t->osthread()->expanding_stack(), "expand should be set"); 693 assert(t->stack_base() != NULL, "stack_base was not initialized"); 694 695 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 696 sigset_t mask_all, old_sigset; 697 sigfillset(&mask_all); 698 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 699 _expand_stack_to(addr); 700 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 701 return true; 702 } 703 return false; 704 } 705 706 ////////////////////////////////////////////////////////////////////////////// 707 // create new thread 708 709 static address highest_vm_reserved_address(); 710 711 // check if it's safe to start a new thread 712 static bool _thread_safety_check(Thread* thread) { 713 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 714 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 715 // Heap is mmap'ed at lower end of memory space. Thread stacks are 716 // allocated (MAP_FIXED) from high address space. Every thread stack 717 // occupies a fixed size slot (usually 2Mbytes, but user can change 718 // it to other values if they rebuild LinuxThreads). 719 // 720 // Problem with MAP_FIXED is that mmap() can still succeed even part of 721 // the memory region has already been mmap'ed. That means if we have too 722 // many threads and/or very large heap, eventually thread stack will 723 // collide with heap. 724 // 725 // Here we try to prevent heap/stack collision by comparing current 726 // stack bottom with the highest address that has been mmap'ed by JVM 727 // plus a safety margin for memory maps created by native code. 728 // 729 // This feature can be disabled by setting ThreadSafetyMargin to 0 730 // 731 if (ThreadSafetyMargin > 0) { 732 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 733 734 // not safe if our stack extends below the safety margin 735 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 736 } else { 737 return true; 738 } 739 } else { 740 // Floating stack LinuxThreads or NPTL: 741 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 742 // there's not enough space left, pthread_create() will fail. If we come 743 // here, that means enough space has been reserved for stack. 744 return true; 745 } 746 } 747 748 // Thread start routine for all newly created threads 749 static void *java_start(Thread *thread) { 750 // Try to randomize the cache line index of hot stack frames. 751 // This helps when threads of the same stack traces evict each other's 752 // cache lines. The threads can be either from the same JVM instance, or 753 // from different JVM instances. The benefit is especially true for 754 // processors with hyperthreading technology. 755 static int counter = 0; 756 int pid = os::current_process_id(); 757 alloca(((pid ^ counter++) & 7) * 128); 758 759 ThreadLocalStorage::set_thread(thread); 760 761 OSThread* osthread = thread->osthread(); 762 Monitor* sync = osthread->startThread_lock(); 763 764 // non floating stack LinuxThreads needs extra check, see above 765 if (!_thread_safety_check(thread)) { 766 // notify parent thread 767 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 768 osthread->set_state(ZOMBIE); 769 sync->notify_all(); 770 return NULL; 771 } 772 773 // thread_id is kernel thread id (similar to Solaris LWP id) 774 osthread->set_thread_id(os::Linux::gettid()); 775 776 if (UseNUMA) { 777 int lgrp_id = os::numa_get_group_id(); 778 if (lgrp_id != -1) { 779 thread->set_lgrp_id(lgrp_id); 780 } 781 } 782 // initialize signal mask for this thread 783 os::Linux::hotspot_sigmask(thread); 784 785 // initialize floating point control register 786 os::Linux::init_thread_fpu_state(); 787 788 // handshaking with parent thread 789 { 790 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 791 792 // notify parent thread 793 osthread->set_state(INITIALIZED); 794 sync->notify_all(); 795 796 // wait until os::start_thread() 797 while (osthread->get_state() == INITIALIZED) { 798 sync->wait(Mutex::_no_safepoint_check_flag); 799 } 800 } 801 802 // call one more level start routine 803 thread->run(); 804 805 return 0; 806 } 807 808 bool os::create_thread(Thread* thread, ThreadType thr_type, 809 size_t stack_size) { 810 assert(thread->osthread() == NULL, "caller responsible"); 811 812 // Allocate the OSThread object 813 OSThread* osthread = new OSThread(NULL, NULL); 814 if (osthread == NULL) { 815 return false; 816 } 817 818 // set the correct thread state 819 osthread->set_thread_type(thr_type); 820 821 // Initial state is ALLOCATED but not INITIALIZED 822 osthread->set_state(ALLOCATED); 823 824 thread->set_osthread(osthread); 825 826 // init thread attributes 827 pthread_attr_t attr; 828 pthread_attr_init(&attr); 829 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 830 831 // stack size 832 if (os::Linux::supports_variable_stack_size()) { 833 // calculate stack size if it's not specified by caller 834 if (stack_size == 0) { 835 stack_size = os::Linux::default_stack_size(thr_type); 836 837 switch (thr_type) { 838 case os::java_thread: 839 // Java threads use ThreadStackSize which default value can be 840 // changed with the flag -Xss 841 assert(JavaThread::stack_size_at_create() > 0, "this should be set"); 842 stack_size = JavaThread::stack_size_at_create(); 843 break; 844 case os::compiler_thread: 845 if (CompilerThreadStackSize > 0) { 846 stack_size = (size_t)(CompilerThreadStackSize * K); 847 break; 848 } // else fall through: 849 // use VMThreadStackSize if CompilerThreadStackSize is not defined 850 case os::vm_thread: 851 case os::pgc_thread: 852 case os::cgc_thread: 853 case os::watcher_thread: 854 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 855 break; 856 } 857 } 858 859 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 860 pthread_attr_setstacksize(&attr, stack_size); 861 } else { 862 // let pthread_create() pick the default value. 863 } 864 865 // glibc guard page 866 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 867 868 ThreadState state; 869 870 { 871 // Serialize thread creation if we are running with fixed stack LinuxThreads 872 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 873 if (lock) { 874 os::Linux::createThread_lock()->lock_without_safepoint_check(); 875 } 876 877 pthread_t tid; 878 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 879 880 pthread_attr_destroy(&attr); 881 882 if (ret != 0) { 883 if (PrintMiscellaneous && (Verbose || WizardMode)) { 884 perror("pthread_create()"); 885 } 886 // Need to clean up stuff we've allocated so far 887 thread->set_osthread(NULL); 888 delete osthread; 889 if (lock) os::Linux::createThread_lock()->unlock(); 890 return false; 891 } 892 893 // Store pthread info into the OSThread 894 osthread->set_pthread_id(tid); 895 896 // Wait until child thread is either initialized or aborted 897 { 898 Monitor* sync_with_child = osthread->startThread_lock(); 899 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 900 while ((state = osthread->get_state()) == ALLOCATED) { 901 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 902 } 903 } 904 905 if (lock) { 906 os::Linux::createThread_lock()->unlock(); 907 } 908 } 909 910 // Aborted due to thread limit being reached 911 if (state == ZOMBIE) { 912 thread->set_osthread(NULL); 913 delete osthread; 914 return false; 915 } 916 917 // The thread is returned suspended (in state INITIALIZED), 918 // and is started higher up in the call chain 919 assert(state == INITIALIZED, "race condition"); 920 return true; 921 } 922 923 ///////////////////////////////////////////////////////////////////////////// 924 // attach existing thread 925 926 // bootstrap the main thread 927 bool os::create_main_thread(JavaThread* thread) { 928 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 929 return create_attached_thread(thread); 930 } 931 932 bool os::create_attached_thread(JavaThread* thread) { 933 #ifdef ASSERT 934 thread->verify_not_published(); 935 #endif 936 937 // Allocate the OSThread object 938 OSThread* osthread = new OSThread(NULL, NULL); 939 940 if (osthread == NULL) { 941 return false; 942 } 943 944 // Store pthread info into the OSThread 945 osthread->set_thread_id(os::Linux::gettid()); 946 osthread->set_pthread_id(::pthread_self()); 947 948 // initialize floating point control register 949 os::Linux::init_thread_fpu_state(); 950 951 // Initial thread state is RUNNABLE 952 osthread->set_state(RUNNABLE); 953 954 thread->set_osthread(osthread); 955 956 if (UseNUMA) { 957 int lgrp_id = os::numa_get_group_id(); 958 if (lgrp_id != -1) { 959 thread->set_lgrp_id(lgrp_id); 960 } 961 } 962 963 if (os::Linux::is_initial_thread()) { 964 // If current thread is initial thread, its stack is mapped on demand, 965 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 966 // the entire stack region to avoid SEGV in stack banging. 967 // It is also useful to get around the heap-stack-gap problem on SuSE 968 // kernel (see 4821821 for details). We first expand stack to the top 969 // of yellow zone, then enable stack yellow zone (order is significant, 970 // enabling yellow zone first will crash JVM on SuSE Linux), so there 971 // is no gap between the last two virtual memory regions. 972 973 JavaThread *jt = (JavaThread *)thread; 974 address addr = jt->stack_yellow_zone_base(); 975 assert(addr != NULL, "initialization problem?"); 976 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 977 978 osthread->set_expanding_stack(); 979 os::Linux::manually_expand_stack(jt, addr); 980 osthread->clear_expanding_stack(); 981 } 982 983 // initialize signal mask for this thread 984 // and save the caller's signal mask 985 os::Linux::hotspot_sigmask(thread); 986 987 return true; 988 } 989 990 void os::pd_start_thread(Thread* thread) { 991 OSThread * osthread = thread->osthread(); 992 assert(osthread->get_state() != INITIALIZED, "just checking"); 993 Monitor* sync_with_child = osthread->startThread_lock(); 994 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 995 sync_with_child->notify(); 996 } 997 998 // Free Linux resources related to the OSThread 999 void os::free_thread(OSThread* osthread) { 1000 assert(osthread != NULL, "osthread not set"); 1001 1002 if (Thread::current()->osthread() == osthread) { 1003 // Restore caller's signal mask 1004 sigset_t sigmask = osthread->caller_sigmask(); 1005 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 1006 } 1007 1008 delete osthread; 1009 } 1010 1011 ////////////////////////////////////////////////////////////////////////////// 1012 // thread local storage 1013 1014 // Restore the thread pointer if the destructor is called. This is in case 1015 // someone from JNI code sets up a destructor with pthread_key_create to run 1016 // detachCurrentThread on thread death. Unless we restore the thread pointer we 1017 // will hang or crash. When detachCurrentThread is called the key will be set 1018 // to null and we will not be called again. If detachCurrentThread is never 1019 // called we could loop forever depending on the pthread implementation. 1020 static void restore_thread_pointer(void* p) { 1021 Thread* thread = (Thread*) p; 1022 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); 1023 } 1024 1025 int os::allocate_thread_local_storage() { 1026 pthread_key_t key; 1027 int rslt = pthread_key_create(&key, restore_thread_pointer); 1028 assert(rslt == 0, "cannot allocate thread local storage"); 1029 return (int)key; 1030 } 1031 1032 // Note: This is currently not used by VM, as we don't destroy TLS key 1033 // on VM exit. 1034 void os::free_thread_local_storage(int index) { 1035 int rslt = pthread_key_delete((pthread_key_t)index); 1036 assert(rslt == 0, "invalid index"); 1037 } 1038 1039 void os::thread_local_storage_at_put(int index, void* value) { 1040 int rslt = pthread_setspecific((pthread_key_t)index, value); 1041 assert(rslt == 0, "pthread_setspecific failed"); 1042 } 1043 1044 extern "C" Thread* get_thread() { 1045 return ThreadLocalStorage::thread(); 1046 } 1047 1048 ////////////////////////////////////////////////////////////////////////////// 1049 // initial thread 1050 1051 // Check if current thread is the initial thread, similar to Solaris thr_main. 1052 bool os::Linux::is_initial_thread(void) { 1053 char dummy; 1054 // If called before init complete, thread stack bottom will be null. 1055 // Can be called if fatal error occurs before initialization. 1056 if (initial_thread_stack_bottom() == NULL) return false; 1057 assert(initial_thread_stack_bottom() != NULL && 1058 initial_thread_stack_size() != 0, 1059 "os::init did not locate initial thread's stack region"); 1060 if ((address)&dummy >= initial_thread_stack_bottom() && 1061 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) { 1062 return true; 1063 } else { 1064 return false; 1065 } 1066 } 1067 1068 // Find the virtual memory area that contains addr 1069 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1070 FILE *fp = fopen("/proc/self/maps", "r"); 1071 if (fp) { 1072 address low, high; 1073 while (!feof(fp)) { 1074 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1075 if (low <= addr && addr < high) { 1076 if (vma_low) *vma_low = low; 1077 if (vma_high) *vma_high = high; 1078 fclose(fp); 1079 return true; 1080 } 1081 } 1082 for (;;) { 1083 int ch = fgetc(fp); 1084 if (ch == EOF || ch == (int)'\n') break; 1085 } 1086 } 1087 fclose(fp); 1088 } 1089 return false; 1090 } 1091 1092 // Locate initial thread stack. This special handling of initial thread stack 1093 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1094 // bogus value for initial thread. 1095 void os::Linux::capture_initial_stack(size_t max_size) { 1096 // stack size is the easy part, get it from RLIMIT_STACK 1097 size_t stack_size; 1098 struct rlimit rlim; 1099 getrlimit(RLIMIT_STACK, &rlim); 1100 stack_size = rlim.rlim_cur; 1101 1102 // 6308388: a bug in ld.so will relocate its own .data section to the 1103 // lower end of primordial stack; reduce ulimit -s value a little bit 1104 // so we won't install guard page on ld.so's data section. 1105 stack_size -= 2 * page_size(); 1106 1107 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1108 // 7.1, in both cases we will get 2G in return value. 1109 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1110 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1111 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1112 // in case other parts in glibc still assumes 2M max stack size. 1113 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1114 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1115 if (stack_size > 2 * K * K IA64_ONLY(*2)) { 1116 stack_size = 2 * K * K IA64_ONLY(*2); 1117 } 1118 // Try to figure out where the stack base (top) is. This is harder. 1119 // 1120 // When an application is started, glibc saves the initial stack pointer in 1121 // a global variable "__libc_stack_end", which is then used by system 1122 // libraries. __libc_stack_end should be pretty close to stack top. The 1123 // variable is available since the very early days. However, because it is 1124 // a private interface, it could disappear in the future. 1125 // 1126 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1127 // to __libc_stack_end, it is very close to stack top, but isn't the real 1128 // stack top. Note that /proc may not exist if VM is running as a chroot 1129 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1130 // /proc/<pid>/stat could change in the future (though unlikely). 1131 // 1132 // We try __libc_stack_end first. If that doesn't work, look for 1133 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1134 // as a hint, which should work well in most cases. 1135 1136 uintptr_t stack_start; 1137 1138 // try __libc_stack_end first 1139 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1140 if (p && *p) { 1141 stack_start = *p; 1142 } else { 1143 // see if we can get the start_stack field from /proc/self/stat 1144 FILE *fp; 1145 int pid; 1146 char state; 1147 int ppid; 1148 int pgrp; 1149 int session; 1150 int nr; 1151 int tpgrp; 1152 unsigned long flags; 1153 unsigned long minflt; 1154 unsigned long cminflt; 1155 unsigned long majflt; 1156 unsigned long cmajflt; 1157 unsigned long utime; 1158 unsigned long stime; 1159 long cutime; 1160 long cstime; 1161 long prio; 1162 long nice; 1163 long junk; 1164 long it_real; 1165 uintptr_t start; 1166 uintptr_t vsize; 1167 intptr_t rss; 1168 uintptr_t rsslim; 1169 uintptr_t scodes; 1170 uintptr_t ecode; 1171 int i; 1172 1173 // Figure what the primordial thread stack base is. Code is inspired 1174 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1175 // followed by command name surrounded by parentheses, state, etc. 1176 char stat[2048]; 1177 int statlen; 1178 1179 fp = fopen("/proc/self/stat", "r"); 1180 if (fp) { 1181 statlen = fread(stat, 1, 2047, fp); 1182 stat[statlen] = '\0'; 1183 fclose(fp); 1184 1185 // Skip pid and the command string. Note that we could be dealing with 1186 // weird command names, e.g. user could decide to rename java launcher 1187 // to "java 1.4.2 :)", then the stat file would look like 1188 // 1234 (java 1.4.2 :)) R ... ... 1189 // We don't really need to know the command string, just find the last 1190 // occurrence of ")" and then start parsing from there. See bug 4726580. 1191 char * s = strrchr(stat, ')'); 1192 1193 i = 0; 1194 if (s) { 1195 // Skip blank chars 1196 do { s++; } while (s && isspace(*s)); 1197 1198 #define _UFM UINTX_FORMAT 1199 #define _DFM INTX_FORMAT 1200 1201 // 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 1202 // 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 1203 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, 1204 &state, // 3 %c 1205 &ppid, // 4 %d 1206 &pgrp, // 5 %d 1207 &session, // 6 %d 1208 &nr, // 7 %d 1209 &tpgrp, // 8 %d 1210 &flags, // 9 %lu 1211 &minflt, // 10 %lu 1212 &cminflt, // 11 %lu 1213 &majflt, // 12 %lu 1214 &cmajflt, // 13 %lu 1215 &utime, // 14 %lu 1216 &stime, // 15 %lu 1217 &cutime, // 16 %ld 1218 &cstime, // 17 %ld 1219 &prio, // 18 %ld 1220 &nice, // 19 %ld 1221 &junk, // 20 %ld 1222 &it_real, // 21 %ld 1223 &start, // 22 UINTX_FORMAT 1224 &vsize, // 23 UINTX_FORMAT 1225 &rss, // 24 INTX_FORMAT 1226 &rsslim, // 25 UINTX_FORMAT 1227 &scodes, // 26 UINTX_FORMAT 1228 &ecode, // 27 UINTX_FORMAT 1229 &stack_start); // 28 UINTX_FORMAT 1230 } 1231 1232 #undef _UFM 1233 #undef _DFM 1234 1235 if (i != 28 - 2) { 1236 assert(false, "Bad conversion from /proc/self/stat"); 1237 // product mode - assume we are the initial thread, good luck in the 1238 // embedded case. 1239 warning("Can't detect initial thread stack location - bad conversion"); 1240 stack_start = (uintptr_t) &rlim; 1241 } 1242 } else { 1243 // For some reason we can't open /proc/self/stat (for example, running on 1244 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1245 // most cases, so don't abort: 1246 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1247 stack_start = (uintptr_t) &rlim; 1248 } 1249 } 1250 1251 // Now we have a pointer (stack_start) very close to the stack top, the 1252 // next thing to do is to figure out the exact location of stack top. We 1253 // can find out the virtual memory area that contains stack_start by 1254 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1255 // and its upper limit is the real stack top. (again, this would fail if 1256 // running inside chroot, because /proc may not exist.) 1257 1258 uintptr_t stack_top; 1259 address low, high; 1260 if (find_vma((address)stack_start, &low, &high)) { 1261 // success, "high" is the true stack top. (ignore "low", because initial 1262 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1263 stack_top = (uintptr_t)high; 1264 } else { 1265 // failed, likely because /proc/self/maps does not exist 1266 warning("Can't detect initial thread stack location - find_vma failed"); 1267 // best effort: stack_start is normally within a few pages below the real 1268 // stack top, use it as stack top, and reduce stack size so we won't put 1269 // guard page outside stack. 1270 stack_top = stack_start; 1271 stack_size -= 16 * page_size(); 1272 } 1273 1274 // stack_top could be partially down the page so align it 1275 stack_top = align_size_up(stack_top, page_size()); 1276 1277 if (max_size && stack_size > max_size) { 1278 _initial_thread_stack_size = max_size; 1279 } else { 1280 _initial_thread_stack_size = stack_size; 1281 } 1282 1283 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1284 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1285 } 1286 1287 //////////////////////////////////////////////////////////////////////////////// 1288 // time support 1289 1290 // Time since start-up in seconds to a fine granularity. 1291 // Used by VMSelfDestructTimer and the MemProfiler. 1292 double os::elapsedTime() { 1293 1294 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution 1295 } 1296 1297 jlong os::elapsed_counter() { 1298 return javaTimeNanos() - initial_time_count; 1299 } 1300 1301 jlong os::elapsed_frequency() { 1302 return NANOSECS_PER_SEC; // nanosecond resolution 1303 } 1304 1305 bool os::supports_vtime() { return true; } 1306 bool os::enable_vtime() { return false; } 1307 bool os::vtime_enabled() { return false; } 1308 1309 double os::elapsedVTime() { 1310 struct rusage usage; 1311 int retval = getrusage(RUSAGE_THREAD, &usage); 1312 if (retval == 0) { 1313 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); 1314 } else { 1315 // better than nothing, but not much 1316 return elapsedTime(); 1317 } 1318 } 1319 1320 jlong os::javaTimeMillis() { 1321 timeval time; 1322 int status = gettimeofday(&time, NULL); 1323 assert(status != -1, "linux error"); 1324 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1325 } 1326 1327 void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) { 1328 timeval time; 1329 int status = gettimeofday(&time, NULL); 1330 assert(status != -1, "linux error"); 1331 seconds = jlong(time.tv_sec); 1332 nanos = jlong(time.tv_usec) * 1000; 1333 } 1334 1335 1336 #ifndef CLOCK_MONOTONIC 1337 #define CLOCK_MONOTONIC (1) 1338 #endif 1339 1340 void os::Linux::clock_init() { 1341 // we do dlopen's in this particular order due to bug in linux 1342 // dynamical loader (see 6348968) leading to crash on exit 1343 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1344 if (handle == NULL) { 1345 handle = dlopen("librt.so", RTLD_LAZY); 1346 } 1347 1348 if (handle) { 1349 int (*clock_getres_func)(clockid_t, struct timespec*) = 1350 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1351 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1352 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1353 if (clock_getres_func && clock_gettime_func) { 1354 // See if monotonic clock is supported by the kernel. Note that some 1355 // early implementations simply return kernel jiffies (updated every 1356 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1357 // for nano time (though the monotonic property is still nice to have). 1358 // It's fixed in newer kernels, however clock_getres() still returns 1359 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1360 // resolution for now. Hopefully as people move to new kernels, this 1361 // won't be a problem. 1362 struct timespec res; 1363 struct timespec tp; 1364 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1365 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1366 // yes, monotonic clock is supported 1367 _clock_gettime = clock_gettime_func; 1368 return; 1369 } else { 1370 // close librt if there is no monotonic clock 1371 dlclose(handle); 1372 } 1373 } 1374 } 1375 warning("No monotonic clock was available - timed services may " \ 1376 "be adversely affected if the time-of-day clock changes"); 1377 } 1378 1379 #ifndef SYS_clock_getres 1380 #if defined(IA32) || defined(AMD64) 1381 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1382 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1383 #else 1384 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1385 #define sys_clock_getres(x,y) -1 1386 #endif 1387 #else 1388 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1389 #endif 1390 1391 void os::Linux::fast_thread_clock_init() { 1392 if (!UseLinuxPosixThreadCPUClocks) { 1393 return; 1394 } 1395 clockid_t clockid; 1396 struct timespec tp; 1397 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1398 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1399 1400 // Switch to using fast clocks for thread cpu time if 1401 // the sys_clock_getres() returns 0 error code. 1402 // Note, that some kernels may support the current thread 1403 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1404 // returned by the pthread_getcpuclockid(). 1405 // If the fast Posix clocks are supported then the sys_clock_getres() 1406 // must return at least tp.tv_sec == 0 which means a resolution 1407 // better than 1 sec. This is extra check for reliability. 1408 1409 if (pthread_getcpuclockid_func && 1410 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1411 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1412 _supports_fast_thread_cpu_time = true; 1413 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1414 } 1415 } 1416 1417 jlong os::javaTimeNanos() { 1418 if (os::supports_monotonic_clock()) { 1419 struct timespec tp; 1420 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1421 assert(status == 0, "gettime error"); 1422 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1423 return result; 1424 } else { 1425 timeval time; 1426 int status = gettimeofday(&time, NULL); 1427 assert(status != -1, "linux error"); 1428 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1429 return 1000 * usecs; 1430 } 1431 } 1432 1433 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1434 if (os::supports_monotonic_clock()) { 1435 info_ptr->max_value = ALL_64_BITS; 1436 1437 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1438 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1439 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1440 } else { 1441 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1442 info_ptr->max_value = ALL_64_BITS; 1443 1444 // gettimeofday is a real time clock so it skips 1445 info_ptr->may_skip_backward = true; 1446 info_ptr->may_skip_forward = true; 1447 } 1448 1449 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1450 } 1451 1452 // Return the real, user, and system times in seconds from an 1453 // arbitrary fixed point in the past. 1454 bool os::getTimesSecs(double* process_real_time, 1455 double* process_user_time, 1456 double* process_system_time) { 1457 struct tms ticks; 1458 clock_t real_ticks = times(&ticks); 1459 1460 if (real_ticks == (clock_t) (-1)) { 1461 return false; 1462 } else { 1463 double ticks_per_second = (double) clock_tics_per_sec; 1464 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1465 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1466 *process_real_time = ((double) real_ticks) / ticks_per_second; 1467 1468 return true; 1469 } 1470 } 1471 1472 1473 char * os::local_time_string(char *buf, size_t buflen) { 1474 struct tm t; 1475 time_t long_time; 1476 time(&long_time); 1477 localtime_r(&long_time, &t); 1478 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1479 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1480 t.tm_hour, t.tm_min, t.tm_sec); 1481 return buf; 1482 } 1483 1484 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1485 return localtime_r(clock, res); 1486 } 1487 1488 //////////////////////////////////////////////////////////////////////////////// 1489 // runtime exit support 1490 1491 // Note: os::shutdown() might be called very early during initialization, or 1492 // called from signal handler. Before adding something to os::shutdown(), make 1493 // sure it is async-safe and can handle partially initialized VM. 1494 void os::shutdown() { 1495 1496 // allow PerfMemory to attempt cleanup of any persistent resources 1497 perfMemory_exit(); 1498 1499 // needs to remove object in file system 1500 AttachListener::abort(); 1501 1502 // flush buffered output, finish log files 1503 ostream_abort(); 1504 1505 // Check for abort hook 1506 abort_hook_t abort_hook = Arguments::abort_hook(); 1507 if (abort_hook != NULL) { 1508 abort_hook(); 1509 } 1510 1511 } 1512 1513 // Note: os::abort() might be called very early during initialization, or 1514 // called from signal handler. Before adding something to os::abort(), make 1515 // sure it is async-safe and can handle partially initialized VM. 1516 void os::abort(bool dump_core) { 1517 os::shutdown(); 1518 if (dump_core) { 1519 #ifndef PRODUCT 1520 fdStream out(defaultStream::output_fd()); 1521 out.print_raw("Current thread is "); 1522 char buf[16]; 1523 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1524 out.print_raw_cr(buf); 1525 out.print_raw_cr("Dumping core ..."); 1526 #endif 1527 ::abort(); // dump core 1528 } 1529 1530 ::exit(1); 1531 } 1532 1533 // Die immediately, no exit hook, no abort hook, no cleanup. 1534 void os::die() { 1535 // _exit() on LinuxThreads only kills current thread 1536 ::abort(); 1537 } 1538 1539 1540 // This method is a copy of JDK's sysGetLastErrorString 1541 // from src/solaris/hpi/src/system_md.c 1542 1543 size_t os::lasterror(char *buf, size_t len) { 1544 if (errno == 0) return 0; 1545 1546 const char *s = ::strerror(errno); 1547 size_t n = ::strlen(s); 1548 if (n >= len) { 1549 n = len - 1; 1550 } 1551 ::strncpy(buf, s, n); 1552 buf[n] = '\0'; 1553 return n; 1554 } 1555 1556 intx os::current_thread_id() { return (intx)pthread_self(); } 1557 int os::current_process_id() { 1558 1559 // Under the old linux thread library, linux gives each thread 1560 // its own process id. Because of this each thread will return 1561 // a different pid if this method were to return the result 1562 // of getpid(2). Linux provides no api that returns the pid 1563 // of the launcher thread for the vm. This implementation 1564 // returns a unique pid, the pid of the launcher thread 1565 // that starts the vm 'process'. 1566 1567 // Under the NPTL, getpid() returns the same pid as the 1568 // launcher thread rather than a unique pid per thread. 1569 // Use gettid() if you want the old pre NPTL behaviour. 1570 1571 // if you are looking for the result of a call to getpid() that 1572 // returns a unique pid for the calling thread, then look at the 1573 // OSThread::thread_id() method in osThread_linux.hpp file 1574 1575 return (int)(_initial_pid ? _initial_pid : getpid()); 1576 } 1577 1578 // DLL functions 1579 1580 const char* os::dll_file_extension() { return ".so"; } 1581 1582 // This must be hard coded because it's the system's temporary 1583 // directory not the java application's temp directory, ala java.io.tmpdir. 1584 const char* os::get_temp_directory() { return "/tmp"; } 1585 1586 static bool file_exists(const char* filename) { 1587 struct stat statbuf; 1588 if (filename == NULL || strlen(filename) == 0) { 1589 return false; 1590 } 1591 return os::stat(filename, &statbuf) == 0; 1592 } 1593 1594 bool os::dll_build_name(char* buffer, size_t buflen, 1595 const char* pname, const char* fname) { 1596 bool retval = false; 1597 // Copied from libhpi 1598 const size_t pnamelen = pname ? strlen(pname) : 0; 1599 1600 // Return error on buffer overflow. 1601 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1602 return retval; 1603 } 1604 1605 if (pnamelen == 0) { 1606 snprintf(buffer, buflen, "lib%s.so", fname); 1607 retval = true; 1608 } else if (strchr(pname, *os::path_separator()) != NULL) { 1609 int n; 1610 char** pelements = split_path(pname, &n); 1611 if (pelements == NULL) { 1612 return false; 1613 } 1614 for (int i = 0; i < n; i++) { 1615 // Really shouldn't be NULL, but check can't hurt 1616 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1617 continue; // skip the empty path values 1618 } 1619 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1620 if (file_exists(buffer)) { 1621 retval = true; 1622 break; 1623 } 1624 } 1625 // release the storage 1626 for (int i = 0; i < n; i++) { 1627 if (pelements[i] != NULL) { 1628 FREE_C_HEAP_ARRAY(char, pelements[i]); 1629 } 1630 } 1631 if (pelements != NULL) { 1632 FREE_C_HEAP_ARRAY(char*, pelements); 1633 } 1634 } else { 1635 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1636 retval = true; 1637 } 1638 return retval; 1639 } 1640 1641 // check if addr is inside libjvm.so 1642 bool os::address_is_in_vm(address addr) { 1643 static address libjvm_base_addr; 1644 Dl_info dlinfo; 1645 1646 if (libjvm_base_addr == NULL) { 1647 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1648 libjvm_base_addr = (address)dlinfo.dli_fbase; 1649 } 1650 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1651 } 1652 1653 if (dladdr((void *)addr, &dlinfo) != 0) { 1654 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1655 } 1656 1657 return false; 1658 } 1659 1660 bool os::dll_address_to_function_name(address addr, char *buf, 1661 int buflen, int *offset) { 1662 // buf is not optional, but offset is optional 1663 assert(buf != NULL, "sanity check"); 1664 1665 Dl_info dlinfo; 1666 1667 if (dladdr((void*)addr, &dlinfo) != 0) { 1668 // see if we have a matching symbol 1669 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1670 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1671 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1672 } 1673 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1674 return true; 1675 } 1676 // no matching symbol so try for just file info 1677 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1678 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1679 buf, buflen, offset, dlinfo.dli_fname)) { 1680 return true; 1681 } 1682 } 1683 } 1684 1685 buf[0] = '\0'; 1686 if (offset != NULL) *offset = -1; 1687 return false; 1688 } 1689 1690 struct _address_to_library_name { 1691 address addr; // input : memory address 1692 size_t buflen; // size of fname 1693 char* fname; // output: library name 1694 address base; // library base addr 1695 }; 1696 1697 static int address_to_library_name_callback(struct dl_phdr_info *info, 1698 size_t size, void *data) { 1699 int i; 1700 bool found = false; 1701 address libbase = NULL; 1702 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1703 1704 // iterate through all loadable segments 1705 for (i = 0; i < info->dlpi_phnum; i++) { 1706 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1707 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1708 // base address of a library is the lowest address of its loaded 1709 // segments. 1710 if (libbase == NULL || libbase > segbase) { 1711 libbase = segbase; 1712 } 1713 // see if 'addr' is within current segment 1714 if (segbase <= d->addr && 1715 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1716 found = true; 1717 } 1718 } 1719 } 1720 1721 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1722 // so dll_address_to_library_name() can fall through to use dladdr() which 1723 // can figure out executable name from argv[0]. 1724 if (found && info->dlpi_name && info->dlpi_name[0]) { 1725 d->base = libbase; 1726 if (d->fname) { 1727 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1728 } 1729 return 1; 1730 } 1731 return 0; 1732 } 1733 1734 bool os::dll_address_to_library_name(address addr, char* buf, 1735 int buflen, int* offset) { 1736 // buf is not optional, but offset is optional 1737 assert(buf != NULL, "sanity check"); 1738 1739 Dl_info dlinfo; 1740 struct _address_to_library_name data; 1741 1742 // There is a bug in old glibc dladdr() implementation that it could resolve 1743 // to wrong library name if the .so file has a base address != NULL. Here 1744 // we iterate through the program headers of all loaded libraries to find 1745 // out which library 'addr' really belongs to. This workaround can be 1746 // removed once the minimum requirement for glibc is moved to 2.3.x. 1747 data.addr = addr; 1748 data.fname = buf; 1749 data.buflen = buflen; 1750 data.base = NULL; 1751 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1752 1753 if (rslt) { 1754 // buf already contains library name 1755 if (offset) *offset = addr - data.base; 1756 return true; 1757 } 1758 if (dladdr((void*)addr, &dlinfo) != 0) { 1759 if (dlinfo.dli_fname != NULL) { 1760 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1761 } 1762 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1763 *offset = addr - (address)dlinfo.dli_fbase; 1764 } 1765 return true; 1766 } 1767 1768 buf[0] = '\0'; 1769 if (offset) *offset = -1; 1770 return false; 1771 } 1772 1773 // Loads .dll/.so and 1774 // in case of error it checks if .dll/.so was built for the 1775 // same architecture as Hotspot is running on 1776 1777 1778 // Remember the stack's state. The Linux dynamic linker will change 1779 // the stack to 'executable' at most once, so we must safepoint only once. 1780 bool os::Linux::_stack_is_executable = false; 1781 1782 // VM operation that loads a library. This is necessary if stack protection 1783 // of the Java stacks can be lost during loading the library. If we 1784 // do not stop the Java threads, they can stack overflow before the stacks 1785 // are protected again. 1786 class VM_LinuxDllLoad: public VM_Operation { 1787 private: 1788 const char *_filename; 1789 char *_ebuf; 1790 int _ebuflen; 1791 void *_lib; 1792 public: 1793 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1794 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1795 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1796 void doit() { 1797 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1798 os::Linux::_stack_is_executable = true; 1799 } 1800 void* loaded_library() { return _lib; } 1801 }; 1802 1803 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) { 1804 void * result = NULL; 1805 bool load_attempted = false; 1806 1807 // Check whether the library to load might change execution rights 1808 // of the stack. If they are changed, the protection of the stack 1809 // guard pages will be lost. We need a safepoint to fix this. 1810 // 1811 // See Linux man page execstack(8) for more info. 1812 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1813 ElfFile ef(filename); 1814 if (!ef.specifies_noexecstack()) { 1815 if (!is_init_completed()) { 1816 os::Linux::_stack_is_executable = true; 1817 // This is OK - No Java threads have been created yet, and hence no 1818 // stack guard pages to fix. 1819 // 1820 // This should happen only when you are building JDK7 using a very 1821 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1822 // 1823 // Dynamic loader will make all stacks executable after 1824 // this function returns, and will not do that again. 1825 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1826 } else { 1827 warning("You have loaded library %s which might have disabled stack guard. " 1828 "The VM will try to fix the stack guard now.\n" 1829 "It's highly recommended that you fix the library with " 1830 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1831 filename); 1832 1833 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1834 JavaThread *jt = JavaThread::current(); 1835 if (jt->thread_state() != _thread_in_native) { 1836 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1837 // that requires ExecStack. Cannot enter safe point. Let's give up. 1838 warning("Unable to fix stack guard. Giving up."); 1839 } else { 1840 if (!LoadExecStackDllInVMThread) { 1841 // This is for the case where the DLL has an static 1842 // constructor function that executes JNI code. We cannot 1843 // load such DLLs in the VMThread. 1844 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1845 } 1846 1847 ThreadInVMfromNative tiv(jt); 1848 debug_only(VMNativeEntryWrapper vew;) 1849 1850 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1851 VMThread::execute(&op); 1852 if (LoadExecStackDllInVMThread) { 1853 result = op.loaded_library(); 1854 } 1855 load_attempted = true; 1856 } 1857 } 1858 } 1859 } 1860 1861 if (!load_attempted) { 1862 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1863 } 1864 1865 if (result != NULL) { 1866 // Successful loading 1867 return result; 1868 } 1869 1870 Elf32_Ehdr elf_head; 1871 int diag_msg_max_length=ebuflen-strlen(ebuf); 1872 char* diag_msg_buf=ebuf+strlen(ebuf); 1873 1874 if (diag_msg_max_length==0) { 1875 // No more space in ebuf for additional diagnostics message 1876 return NULL; 1877 } 1878 1879 1880 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1881 1882 if (file_descriptor < 0) { 1883 // Can't open library, report dlerror() message 1884 return NULL; 1885 } 1886 1887 bool failed_to_read_elf_head= 1888 (sizeof(elf_head)!= 1889 (::read(file_descriptor, &elf_head,sizeof(elf_head)))); 1890 1891 ::close(file_descriptor); 1892 if (failed_to_read_elf_head) { 1893 // file i/o error - report dlerror() msg 1894 return NULL; 1895 } 1896 1897 typedef struct { 1898 Elf32_Half code; // Actual value as defined in elf.h 1899 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1900 char elf_class; // 32 or 64 bit 1901 char endianess; // MSB or LSB 1902 char* name; // String representation 1903 } arch_t; 1904 1905 #ifndef EM_486 1906 #define EM_486 6 /* Intel 80486 */ 1907 #endif 1908 #ifndef EM_AARCH64 1909 #define EM_AARCH64 183 /* ARM AARCH64 */ 1910 #endif 1911 1912 static const arch_t arch_array[]={ 1913 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1914 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1915 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1916 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1917 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1918 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1919 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1920 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1921 #if defined(VM_LITTLE_ENDIAN) 1922 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"}, 1923 #else 1924 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1925 #endif 1926 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1927 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1928 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1929 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1930 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1931 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1932 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}, 1933 {EM_AARCH64, EM_AARCH64, ELFCLASS64, ELFDATA2LSB, (char*)"AARCH64"}, 1934 }; 1935 1936 #if (defined IA32) 1937 static Elf32_Half running_arch_code=EM_386; 1938 #elif (defined AMD64) 1939 static Elf32_Half running_arch_code=EM_X86_64; 1940 #elif (defined IA64) 1941 static Elf32_Half running_arch_code=EM_IA_64; 1942 #elif (defined __sparc) && (defined _LP64) 1943 static Elf32_Half running_arch_code=EM_SPARCV9; 1944 #elif (defined __sparc) && (!defined _LP64) 1945 static Elf32_Half running_arch_code=EM_SPARC; 1946 #elif (defined __powerpc64__) 1947 static Elf32_Half running_arch_code=EM_PPC64; 1948 #elif (defined __powerpc__) 1949 static Elf32_Half running_arch_code=EM_PPC; 1950 #elif (defined ARM) 1951 static Elf32_Half running_arch_code=EM_ARM; 1952 #elif (defined S390) 1953 static Elf32_Half running_arch_code=EM_S390; 1954 #elif (defined ALPHA) 1955 static Elf32_Half running_arch_code=EM_ALPHA; 1956 #elif (defined MIPSEL) 1957 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1958 #elif (defined PARISC) 1959 static Elf32_Half running_arch_code=EM_PARISC; 1960 #elif (defined MIPS) 1961 static Elf32_Half running_arch_code=EM_MIPS; 1962 #elif (defined M68K) 1963 static Elf32_Half running_arch_code=EM_68K; 1964 #elif (defined AARCH64) 1965 static Elf32_Half running_arch_code=EM_AARCH64; 1966 #else 1967 #error Method os::dll_load requires that one of following is defined:\ 1968 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K, AARCH64 1969 #endif 1970 1971 // Identify compatability class for VM's architecture and library's architecture 1972 // Obtain string descriptions for architectures 1973 1974 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1975 int running_arch_index=-1; 1976 1977 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) { 1978 if (running_arch_code == arch_array[i].code) { 1979 running_arch_index = i; 1980 } 1981 if (lib_arch.code == arch_array[i].code) { 1982 lib_arch.compat_class = arch_array[i].compat_class; 1983 lib_arch.name = arch_array[i].name; 1984 } 1985 } 1986 1987 assert(running_arch_index != -1, 1988 "Didn't find running architecture code (running_arch_code) in arch_array"); 1989 if (running_arch_index == -1) { 1990 // Even though running architecture detection failed 1991 // we may still continue with reporting dlerror() message 1992 return NULL; 1993 } 1994 1995 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1996 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1997 return NULL; 1998 } 1999 2000 #ifndef S390 2001 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 2002 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 2003 return NULL; 2004 } 2005 #endif // !S390 2006 2007 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 2008 if (lib_arch.name!=NULL) { 2009 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2010 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 2011 lib_arch.name, arch_array[running_arch_index].name); 2012 } else { 2013 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 2014 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 2015 lib_arch.code, 2016 arch_array[running_arch_index].name); 2017 } 2018 } 2019 2020 return NULL; 2021 } 2022 2023 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, 2024 int ebuflen) { 2025 void * result = ::dlopen(filename, RTLD_LAZY); 2026 if (result == NULL) { 2027 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 2028 ebuf[ebuflen-1] = '\0'; 2029 } 2030 return result; 2031 } 2032 2033 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, 2034 int ebuflen) { 2035 void * result = NULL; 2036 if (LoadExecStackDllInVMThread) { 2037 result = dlopen_helper(filename, ebuf, ebuflen); 2038 } 2039 2040 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2041 // library that requires an executable stack, or which does not have this 2042 // stack attribute set, dlopen changes the stack attribute to executable. The 2043 // read protection of the guard pages gets lost. 2044 // 2045 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2046 // may have been queued at the same time. 2047 2048 if (!_stack_is_executable) { 2049 JavaThread *jt = Threads::first(); 2050 2051 while (jt) { 2052 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2053 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2054 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2055 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2056 warning("Attempt to reguard stack yellow zone failed."); 2057 } 2058 } 2059 jt = jt->next(); 2060 } 2061 } 2062 2063 return result; 2064 } 2065 2066 // glibc-2.0 libdl is not MT safe. If you are building with any glibc, 2067 // chances are you might want to run the generated bits against glibc-2.0 2068 // libdl.so, so always use locking for any version of glibc. 2069 // 2070 void* os::dll_lookup(void* handle, const char* name) { 2071 pthread_mutex_lock(&dl_mutex); 2072 void* res = dlsym(handle, name); 2073 pthread_mutex_unlock(&dl_mutex); 2074 return res; 2075 } 2076 2077 void* os::get_default_process_handle() { 2078 return (void*)::dlopen(NULL, RTLD_LAZY); 2079 } 2080 2081 static bool _print_ascii_file(const char* filename, outputStream* st) { 2082 int fd = ::open(filename, O_RDONLY); 2083 if (fd == -1) { 2084 return false; 2085 } 2086 2087 char buf[32]; 2088 int bytes; 2089 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2090 st->print_raw(buf, bytes); 2091 } 2092 2093 ::close(fd); 2094 2095 return true; 2096 } 2097 2098 void os::print_dll_info(outputStream *st) { 2099 st->print_cr("Dynamic libraries:"); 2100 2101 char fname[32]; 2102 pid_t pid = os::Linux::gettid(); 2103 2104 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2105 2106 if (!_print_ascii_file(fname, st)) { 2107 st->print("Can not get library information for pid = %d\n", pid); 2108 } 2109 } 2110 2111 int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) { 2112 FILE *procmapsFile = NULL; 2113 2114 // Open the procfs maps file for the current process 2115 if ((procmapsFile = fopen("/proc/self/maps", "r")) != NULL) { 2116 // Allocate PATH_MAX for file name plus a reasonable size for other fields. 2117 char line[PATH_MAX + 100]; 2118 2119 // Read line by line from 'file' 2120 while (fgets(line, sizeof(line), procmapsFile) != NULL) { 2121 u8 base, top, offset, inode; 2122 char permissions[5]; 2123 char device[6]; 2124 char name[PATH_MAX + 1]; 2125 2126 // Parse fields from line 2127 sscanf(line, "%lx-%lx %4s %lx %5s %ld %s", &base, &top, permissions, &offset, device, &inode, name); 2128 2129 // Filter by device id '00:00' so that we only get file system mapped files. 2130 if (strcmp(device, "00:00") != 0) { 2131 2132 // Call callback with the fields of interest 2133 if(callback(name, (address)base, (address)top, param)) { 2134 // Oops abort, callback aborted 2135 fclose(procmapsFile); 2136 return 1; 2137 } 2138 } 2139 } 2140 fclose(procmapsFile); 2141 } 2142 return 0; 2143 } 2144 2145 void os::print_os_info_brief(outputStream* st) { 2146 os::Linux::print_distro_info(st); 2147 2148 os::Posix::print_uname_info(st); 2149 2150 os::Linux::print_libversion_info(st); 2151 2152 } 2153 2154 void os::print_os_info(outputStream* st) { 2155 st->print("OS:"); 2156 2157 os::Linux::print_distro_info(st); 2158 2159 os::Posix::print_uname_info(st); 2160 2161 // Print warning if unsafe chroot environment detected 2162 if (unsafe_chroot_detected) { 2163 st->print("WARNING!! "); 2164 st->print_cr("%s", unstable_chroot_error); 2165 } 2166 2167 os::Linux::print_libversion_info(st); 2168 2169 os::Posix::print_rlimit_info(st); 2170 2171 os::Posix::print_load_average(st); 2172 2173 os::Linux::print_full_memory_info(st); 2174 } 2175 2176 // Try to identify popular distros. 2177 // Most Linux distributions have a /etc/XXX-release file, which contains 2178 // the OS version string. Newer Linux distributions have a /etc/lsb-release 2179 // file that also contains the OS version string. Some have more than one 2180 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2181 // /etc/redhat-release.), so the order is important. 2182 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2183 // their own specific XXX-release file as well as a redhat-release file. 2184 // Because of this the XXX-release file needs to be searched for before the 2185 // redhat-release file. 2186 // Since Red Hat has a lsb-release file that is not very descriptive the 2187 // search for redhat-release needs to be before lsb-release. 2188 // Since the lsb-release file is the new standard it needs to be searched 2189 // before the older style release files. 2190 // Searching system-release (Red Hat) and os-release (other Linuxes) are a 2191 // next to last resort. The os-release file is a new standard that contains 2192 // distribution information and the system-release file seems to be an old 2193 // standard that has been replaced by the lsb-release and os-release files. 2194 // Searching for the debian_version file is the last resort. It contains 2195 // an informative string like "6.0.6" or "wheezy/sid". Because of this 2196 // "Debian " is printed before the contents of the debian_version file. 2197 void os::Linux::print_distro_info(outputStream* st) { 2198 if (!_print_ascii_file("/etc/oracle-release", st) && 2199 !_print_ascii_file("/etc/mandriva-release", st) && 2200 !_print_ascii_file("/etc/mandrake-release", st) && 2201 !_print_ascii_file("/etc/sun-release", st) && 2202 !_print_ascii_file("/etc/redhat-release", st) && 2203 !_print_ascii_file("/etc/lsb-release", st) && 2204 !_print_ascii_file("/etc/SuSE-release", st) && 2205 !_print_ascii_file("/etc/turbolinux-release", st) && 2206 !_print_ascii_file("/etc/gentoo-release", st) && 2207 !_print_ascii_file("/etc/ltib-release", st) && 2208 !_print_ascii_file("/etc/angstrom-version", st) && 2209 !_print_ascii_file("/etc/system-release", st) && 2210 !_print_ascii_file("/etc/os-release", st)) { 2211 2212 if (file_exists("/etc/debian_version")) { 2213 st->print("Debian "); 2214 _print_ascii_file("/etc/debian_version", st); 2215 } else { 2216 st->print("Linux"); 2217 } 2218 } 2219 st->cr(); 2220 } 2221 2222 void os::Linux::print_libversion_info(outputStream* st) { 2223 // libc, pthread 2224 st->print("libc:"); 2225 st->print("%s ", os::Linux::glibc_version()); 2226 st->print("%s ", os::Linux::libpthread_version()); 2227 if (os::Linux::is_LinuxThreads()) { 2228 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2229 } 2230 st->cr(); 2231 } 2232 2233 void os::Linux::print_full_memory_info(outputStream* st) { 2234 st->print("\n/proc/meminfo:\n"); 2235 _print_ascii_file("/proc/meminfo", st); 2236 st->cr(); 2237 } 2238 2239 void os::print_memory_info(outputStream* st) { 2240 2241 st->print("Memory:"); 2242 st->print(" %dk page", os::vm_page_size()>>10); 2243 2244 // values in struct sysinfo are "unsigned long" 2245 struct sysinfo si; 2246 sysinfo(&si); 2247 2248 st->print(", physical " UINT64_FORMAT "k", 2249 os::physical_memory() >> 10); 2250 st->print("(" UINT64_FORMAT "k free)", 2251 os::available_memory() >> 10); 2252 st->print(", swap " UINT64_FORMAT "k", 2253 ((jlong)si.totalswap * si.mem_unit) >> 10); 2254 st->print("(" UINT64_FORMAT "k free)", 2255 ((jlong)si.freeswap * si.mem_unit) >> 10); 2256 st->cr(); 2257 } 2258 2259 void os::pd_print_cpu_info(outputStream* st) { 2260 st->print("\n/proc/cpuinfo:\n"); 2261 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2262 st->print(" <Not Available>"); 2263 } 2264 st->cr(); 2265 } 2266 2267 void os::print_siginfo(outputStream* st, void* siginfo) { 2268 const siginfo_t* si = (const siginfo_t*)siginfo; 2269 2270 os::Posix::print_siginfo_brief(st, si); 2271 #if INCLUDE_CDS 2272 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2273 UseSharedSpaces) { 2274 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2275 if (mapinfo->is_in_shared_space(si->si_addr)) { 2276 st->print("\n\nError accessing class data sharing archive." \ 2277 " Mapped file inaccessible during execution, " \ 2278 " possible disk/network problem."); 2279 } 2280 } 2281 #endif 2282 st->cr(); 2283 } 2284 2285 2286 static void print_signal_handler(outputStream* st, int sig, 2287 char* buf, size_t buflen); 2288 2289 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2290 st->print_cr("Signal Handlers:"); 2291 print_signal_handler(st, SIGSEGV, buf, buflen); 2292 print_signal_handler(st, SIGBUS , buf, buflen); 2293 print_signal_handler(st, SIGFPE , buf, buflen); 2294 print_signal_handler(st, SIGPIPE, buf, buflen); 2295 print_signal_handler(st, SIGXFSZ, buf, buflen); 2296 print_signal_handler(st, SIGILL , buf, buflen); 2297 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2298 print_signal_handler(st, SR_signum, buf, buflen); 2299 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2300 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2301 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2302 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2303 #if defined(PPC64) 2304 print_signal_handler(st, SIGTRAP, buf, buflen); 2305 #endif 2306 } 2307 2308 static char saved_jvm_path[MAXPATHLEN] = {0}; 2309 2310 // Find the full path to the current module, libjvm.so 2311 void os::jvm_path(char *buf, jint buflen) { 2312 // Error checking. 2313 if (buflen < MAXPATHLEN) { 2314 assert(false, "must use a large-enough buffer"); 2315 buf[0] = '\0'; 2316 return; 2317 } 2318 // Lazy resolve the path to current module. 2319 if (saved_jvm_path[0] != 0) { 2320 strcpy(buf, saved_jvm_path); 2321 return; 2322 } 2323 2324 char dli_fname[MAXPATHLEN]; 2325 bool ret = dll_address_to_library_name( 2326 CAST_FROM_FN_PTR(address, os::jvm_path), 2327 dli_fname, sizeof(dli_fname), NULL); 2328 assert(ret, "cannot locate libjvm"); 2329 char *rp = NULL; 2330 if (ret && dli_fname[0] != '\0') { 2331 rp = realpath(dli_fname, buf); 2332 } 2333 if (rp == NULL) { 2334 return; 2335 } 2336 2337 if (Arguments::sun_java_launcher_is_altjvm()) { 2338 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical 2339 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". 2340 // If "/jre/lib/" appears at the right place in the string, then 2341 // assume we are installed in a JDK and we're done. Otherwise, check 2342 // for a JAVA_HOME environment variable and fix up the path so it 2343 // looks like libjvm.so is installed there (append a fake suffix 2344 // hotspot/libjvm.so). 2345 const char *p = buf + strlen(buf) - 1; 2346 for (int count = 0; p > buf && count < 5; ++count) { 2347 for (--p; p > buf && *p != '/'; --p) 2348 /* empty */ ; 2349 } 2350 2351 if (strncmp(p, "/jre/lib/", 9) != 0) { 2352 // Look for JAVA_HOME in the environment. 2353 char* java_home_var = ::getenv("JAVA_HOME"); 2354 if (java_home_var != NULL && java_home_var[0] != 0) { 2355 char* jrelib_p; 2356 int len; 2357 2358 // Check the current module name "libjvm.so". 2359 p = strrchr(buf, '/'); 2360 if (p == NULL) { 2361 return; 2362 } 2363 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2364 2365 rp = realpath(java_home_var, buf); 2366 if (rp == NULL) { 2367 return; 2368 } 2369 2370 // determine if this is a legacy image or modules image 2371 // modules image doesn't have "jre" subdirectory 2372 len = strlen(buf); 2373 assert(len < buflen, "Ran out of buffer room"); 2374 jrelib_p = buf + len; 2375 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2376 if (0 != access(buf, F_OK)) { 2377 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2378 } 2379 2380 if (0 == access(buf, F_OK)) { 2381 // Use current module name "libjvm.so" 2382 len = strlen(buf); 2383 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2384 } else { 2385 // Go back to path of .so 2386 rp = realpath(dli_fname, buf); 2387 if (rp == NULL) { 2388 return; 2389 } 2390 } 2391 } 2392 } 2393 } 2394 2395 strncpy(saved_jvm_path, buf, MAXPATHLEN); 2396 saved_jvm_path[MAXPATHLEN - 1] = '\0'; 2397 } 2398 2399 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2400 // no prefix required, not even "_" 2401 } 2402 2403 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2404 // no suffix required 2405 } 2406 2407 //////////////////////////////////////////////////////////////////////////////// 2408 // sun.misc.Signal support 2409 2410 static volatile jint sigint_count = 0; 2411 2412 static void UserHandler(int sig, void *siginfo, void *context) { 2413 // 4511530 - sem_post is serialized and handled by the manager thread. When 2414 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2415 // don't want to flood the manager thread with sem_post requests. 2416 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) { 2417 return; 2418 } 2419 2420 // Ctrl-C is pressed during error reporting, likely because the error 2421 // handler fails to abort. Let VM die immediately. 2422 if (sig == SIGINT && is_error_reported()) { 2423 os::die(); 2424 } 2425 2426 os::signal_notify(sig); 2427 } 2428 2429 void* os::user_handler() { 2430 return CAST_FROM_FN_PTR(void*, UserHandler); 2431 } 2432 2433 class Semaphore : public StackObj { 2434 public: 2435 Semaphore(); 2436 ~Semaphore(); 2437 void signal(); 2438 void wait(); 2439 bool trywait(); 2440 bool timedwait(unsigned int sec, int nsec); 2441 private: 2442 sem_t _semaphore; 2443 }; 2444 2445 Semaphore::Semaphore() { 2446 sem_init(&_semaphore, 0, 0); 2447 } 2448 2449 Semaphore::~Semaphore() { 2450 sem_destroy(&_semaphore); 2451 } 2452 2453 void Semaphore::signal() { 2454 sem_post(&_semaphore); 2455 } 2456 2457 void Semaphore::wait() { 2458 sem_wait(&_semaphore); 2459 } 2460 2461 bool Semaphore::trywait() { 2462 return sem_trywait(&_semaphore) == 0; 2463 } 2464 2465 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2466 2467 struct timespec ts; 2468 // Semaphore's are always associated with CLOCK_REALTIME 2469 os::Linux::clock_gettime(CLOCK_REALTIME, &ts); 2470 // see unpackTime for discussion on overflow checking 2471 if (sec >= MAX_SECS) { 2472 ts.tv_sec += MAX_SECS; 2473 ts.tv_nsec = 0; 2474 } else { 2475 ts.tv_sec += sec; 2476 ts.tv_nsec += nsec; 2477 if (ts.tv_nsec >= NANOSECS_PER_SEC) { 2478 ts.tv_nsec -= NANOSECS_PER_SEC; 2479 ++ts.tv_sec; // note: this must be <= max_secs 2480 } 2481 } 2482 2483 while (1) { 2484 int result = sem_timedwait(&_semaphore, &ts); 2485 if (result == 0) { 2486 return true; 2487 } else if (errno == EINTR) { 2488 continue; 2489 } else if (errno == ETIMEDOUT) { 2490 return false; 2491 } else { 2492 return false; 2493 } 2494 } 2495 } 2496 2497 extern "C" { 2498 typedef void (*sa_handler_t)(int); 2499 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2500 } 2501 2502 void* os::signal(int signal_number, void* handler) { 2503 struct sigaction sigAct, oldSigAct; 2504 2505 sigfillset(&(sigAct.sa_mask)); 2506 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2507 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2508 2509 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2510 // -1 means registration failed 2511 return (void *)-1; 2512 } 2513 2514 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2515 } 2516 2517 void os::signal_raise(int signal_number) { 2518 ::raise(signal_number); 2519 } 2520 2521 // The following code is moved from os.cpp for making this 2522 // code platform specific, which it is by its very nature. 2523 2524 // Will be modified when max signal is changed to be dynamic 2525 int os::sigexitnum_pd() { 2526 return NSIG; 2527 } 2528 2529 // a counter for each possible signal value 2530 static volatile jint pending_signals[NSIG+1] = { 0 }; 2531 2532 // Linux(POSIX) specific hand shaking semaphore. 2533 static sem_t sig_sem; 2534 static Semaphore sr_semaphore; 2535 2536 void os::signal_init_pd() { 2537 // Initialize signal structures 2538 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2539 2540 // Initialize signal semaphore 2541 ::sem_init(&sig_sem, 0, 0); 2542 } 2543 2544 void os::signal_notify(int sig) { 2545 Atomic::inc(&pending_signals[sig]); 2546 ::sem_post(&sig_sem); 2547 } 2548 2549 static int check_pending_signals(bool wait) { 2550 Atomic::store(0, &sigint_count); 2551 for (;;) { 2552 for (int i = 0; i < NSIG + 1; i++) { 2553 jint n = pending_signals[i]; 2554 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2555 return i; 2556 } 2557 } 2558 if (!wait) { 2559 return -1; 2560 } 2561 JavaThread *thread = JavaThread::current(); 2562 ThreadBlockInVM tbivm(thread); 2563 2564 bool threadIsSuspended; 2565 do { 2566 thread->set_suspend_equivalent(); 2567 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2568 ::sem_wait(&sig_sem); 2569 2570 // were we externally suspended while we were waiting? 2571 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2572 if (threadIsSuspended) { 2573 // The semaphore has been incremented, but while we were waiting 2574 // another thread suspended us. We don't want to continue running 2575 // while suspended because that would surprise the thread that 2576 // suspended us. 2577 ::sem_post(&sig_sem); 2578 2579 thread->java_suspend_self(); 2580 } 2581 } while (threadIsSuspended); 2582 } 2583 } 2584 2585 int os::signal_lookup() { 2586 return check_pending_signals(false); 2587 } 2588 2589 int os::signal_wait() { 2590 return check_pending_signals(true); 2591 } 2592 2593 //////////////////////////////////////////////////////////////////////////////// 2594 // Virtual Memory 2595 2596 int os::vm_page_size() { 2597 // Seems redundant as all get out 2598 assert(os::Linux::page_size() != -1, "must call os::init"); 2599 return os::Linux::page_size(); 2600 } 2601 2602 // Solaris allocates memory by pages. 2603 int os::vm_allocation_granularity() { 2604 assert(os::Linux::page_size() != -1, "must call os::init"); 2605 return os::Linux::page_size(); 2606 } 2607 2608 // Rationale behind this function: 2609 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2610 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2611 // samples for JITted code. Here we create private executable mapping over the code cache 2612 // and then we can use standard (well, almost, as mapping can change) way to provide 2613 // info for the reporting script by storing timestamp and location of symbol 2614 void linux_wrap_code(char* base, size_t size) { 2615 static volatile jint cnt = 0; 2616 2617 if (!UseOprofile) { 2618 return; 2619 } 2620 2621 char buf[PATH_MAX+1]; 2622 int num = Atomic::add(1, &cnt); 2623 2624 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2625 os::get_temp_directory(), os::current_process_id(), num); 2626 unlink(buf); 2627 2628 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2629 2630 if (fd != -1) { 2631 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2632 if (rv != (off_t)-1) { 2633 if (::write(fd, "", 1) == 1) { 2634 mmap(base, size, 2635 PROT_READ|PROT_WRITE|PROT_EXEC, 2636 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2637 } 2638 } 2639 ::close(fd); 2640 unlink(buf); 2641 } 2642 } 2643 2644 static bool recoverable_mmap_error(int err) { 2645 // See if the error is one we can let the caller handle. This 2646 // list of errno values comes from JBS-6843484. I can't find a 2647 // Linux man page that documents this specific set of errno 2648 // values so while this list currently matches Solaris, it may 2649 // change as we gain experience with this failure mode. 2650 switch (err) { 2651 case EBADF: 2652 case EINVAL: 2653 case ENOTSUP: 2654 // let the caller deal with these errors 2655 return true; 2656 2657 default: 2658 // Any remaining errors on this OS can cause our reserved mapping 2659 // to be lost. That can cause confusion where different data 2660 // structures think they have the same memory mapped. The worst 2661 // scenario is if both the VM and a library think they have the 2662 // same memory mapped. 2663 return false; 2664 } 2665 } 2666 2667 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2668 int err) { 2669 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2670 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2671 strerror(err), err); 2672 } 2673 2674 static void warn_fail_commit_memory(char* addr, size_t size, 2675 size_t alignment_hint, bool exec, 2676 int err) { 2677 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2678 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2679 alignment_hint, exec, strerror(err), err); 2680 } 2681 2682 // NOTE: Linux kernel does not really reserve the pages for us. 2683 // All it does is to check if there are enough free pages 2684 // left at the time of mmap(). This could be a potential 2685 // problem. 2686 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2687 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2688 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2689 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2690 if (res != (uintptr_t) MAP_FAILED) { 2691 if (UseNUMAInterleaving) { 2692 numa_make_global(addr, size); 2693 } 2694 return 0; 2695 } 2696 2697 int err = errno; // save errno from mmap() call above 2698 2699 if (!recoverable_mmap_error(err)) { 2700 warn_fail_commit_memory(addr, size, exec, err); 2701 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2702 } 2703 2704 return err; 2705 } 2706 2707 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2708 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2709 } 2710 2711 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2712 const char* mesg) { 2713 assert(mesg != NULL, "mesg must be specified"); 2714 int err = os::Linux::commit_memory_impl(addr, size, exec); 2715 if (err != 0) { 2716 // the caller wants all commit errors to exit with the specified mesg: 2717 warn_fail_commit_memory(addr, size, exec, err); 2718 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2719 } 2720 } 2721 2722 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2723 #ifndef MAP_HUGETLB 2724 #define MAP_HUGETLB 0x40000 2725 #endif 2726 2727 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2728 #ifndef MADV_HUGEPAGE 2729 #define MADV_HUGEPAGE 14 2730 #endif 2731 2732 int os::Linux::commit_memory_impl(char* addr, size_t size, 2733 size_t alignment_hint, bool exec) { 2734 int err = os::Linux::commit_memory_impl(addr, size, exec); 2735 if (err == 0) { 2736 realign_memory(addr, size, alignment_hint); 2737 } 2738 return err; 2739 } 2740 2741 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2742 bool exec) { 2743 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2744 } 2745 2746 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2747 size_t alignment_hint, bool exec, 2748 const char* mesg) { 2749 assert(mesg != NULL, "mesg must be specified"); 2750 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2751 if (err != 0) { 2752 // the caller wants all commit errors to exit with the specified mesg: 2753 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2754 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2755 } 2756 } 2757 2758 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2759 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2760 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2761 // be supported or the memory may already be backed by huge pages. 2762 ::madvise(addr, bytes, MADV_HUGEPAGE); 2763 } 2764 } 2765 2766 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2767 // This method works by doing an mmap over an existing mmaping and effectively discarding 2768 // the existing pages. However it won't work for SHM-based large pages that cannot be 2769 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2770 // small pages on top of the SHM segment. This method always works for small pages, so we 2771 // allow that in any case. 2772 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2773 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2774 } 2775 } 2776 2777 void os::numa_make_global(char *addr, size_t bytes) { 2778 Linux::numa_interleave_memory(addr, bytes); 2779 } 2780 2781 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2782 // bind policy to MPOL_PREFERRED for the current thread. 2783 #define USE_MPOL_PREFERRED 0 2784 2785 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2786 // To make NUMA and large pages more robust when both enabled, we need to ease 2787 // the requirements on where the memory should be allocated. MPOL_BIND is the 2788 // default policy and it will force memory to be allocated on the specified 2789 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2790 // the specified node, but will not force it. Using this policy will prevent 2791 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2792 // free large pages. 2793 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2794 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2795 } 2796 2797 bool os::numa_topology_changed() { return false; } 2798 2799 size_t os::numa_get_groups_num() { 2800 int max_node = Linux::numa_max_node(); 2801 return max_node > 0 ? max_node + 1 : 1; 2802 } 2803 2804 int os::numa_get_group_id() { 2805 int cpu_id = Linux::sched_getcpu(); 2806 if (cpu_id != -1) { 2807 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2808 if (lgrp_id != -1) { 2809 return lgrp_id; 2810 } 2811 } 2812 return 0; 2813 } 2814 2815 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2816 for (size_t i = 0; i < size; i++) { 2817 ids[i] = i; 2818 } 2819 return size; 2820 } 2821 2822 bool os::get_page_info(char *start, page_info* info) { 2823 return false; 2824 } 2825 2826 char *os::scan_pages(char *start, char* end, page_info* page_expected, 2827 page_info* page_found) { 2828 return end; 2829 } 2830 2831 2832 int os::Linux::sched_getcpu_syscall(void) { 2833 unsigned int cpu; 2834 int retval = -1; 2835 2836 #if defined(IA32) 2837 #ifndef SYS_getcpu 2838 #define SYS_getcpu 318 2839 #endif 2840 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2841 #elif defined(AMD64) 2842 // Unfortunately we have to bring all these macros here from vsyscall.h 2843 // to be able to compile on old linuxes. 2844 #define __NR_vgetcpu 2 2845 #define VSYSCALL_START (-10UL << 20) 2846 #define VSYSCALL_SIZE 1024 2847 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2848 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2849 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2850 retval = vgetcpu(&cpu, NULL, NULL); 2851 #endif 2852 2853 return (retval == -1) ? retval : cpu; 2854 } 2855 2856 // Something to do with the numa-aware allocator needs these symbols 2857 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2858 extern "C" JNIEXPORT void numa_error(char *where) { } 2859 extern "C" JNIEXPORT int fork1() { return fork(); } 2860 2861 2862 // If we are running with libnuma version > 2, then we should 2863 // be trying to use symbols with versions 1.1 2864 // If we are running with earlier version, which did not have symbol versions, 2865 // we should use the base version. 2866 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2867 void *f = dlvsym(handle, name, "libnuma_1.1"); 2868 if (f == NULL) { 2869 f = dlsym(handle, name); 2870 } 2871 return f; 2872 } 2873 2874 bool os::Linux::libnuma_init() { 2875 // sched_getcpu() should be in libc. 2876 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2877 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2878 2879 // If it's not, try a direct syscall. 2880 if (sched_getcpu() == -1) { 2881 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2882 (void*)&sched_getcpu_syscall)); 2883 } 2884 2885 if (sched_getcpu() != -1) { // Does it work? 2886 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2887 if (handle != NULL) { 2888 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2889 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2890 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2891 libnuma_dlsym(handle, "numa_max_node"))); 2892 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2893 libnuma_dlsym(handle, "numa_available"))); 2894 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2895 libnuma_dlsym(handle, "numa_tonode_memory"))); 2896 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2897 libnuma_dlsym(handle, "numa_interleave_memory"))); 2898 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2899 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2900 2901 2902 if (numa_available() != -1) { 2903 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2904 // Create a cpu -> node mapping 2905 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2906 rebuild_cpu_to_node_map(); 2907 return true; 2908 } 2909 } 2910 } 2911 return false; 2912 } 2913 2914 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2915 // The table is later used in get_node_by_cpu(). 2916 void os::Linux::rebuild_cpu_to_node_map() { 2917 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2918 // in libnuma (possible values are starting from 16, 2919 // and continuing up with every other power of 2, but less 2920 // than the maximum number of CPUs supported by kernel), and 2921 // is a subject to change (in libnuma version 2 the requirements 2922 // are more reasonable) we'll just hardcode the number they use 2923 // in the library. 2924 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2925 2926 size_t cpu_num = os::active_processor_count(); 2927 size_t cpu_map_size = NCPUS / BitsPerCLong; 2928 size_t cpu_map_valid_size = 2929 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2930 2931 cpu_to_node()->clear(); 2932 cpu_to_node()->at_grow(cpu_num - 1); 2933 size_t node_num = numa_get_groups_num(); 2934 2935 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2936 for (size_t i = 0; i < node_num; i++) { 2937 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2938 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2939 if (cpu_map[j] != 0) { 2940 for (size_t k = 0; k < BitsPerCLong; k++) { 2941 if (cpu_map[j] & (1UL << k)) { 2942 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2943 } 2944 } 2945 } 2946 } 2947 } 2948 } 2949 FREE_C_HEAP_ARRAY(unsigned long, cpu_map); 2950 } 2951 2952 int os::Linux::get_node_by_cpu(int cpu_id) { 2953 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2954 return cpu_to_node()->at(cpu_id); 2955 } 2956 return -1; 2957 } 2958 2959 GrowableArray<int>* os::Linux::_cpu_to_node; 2960 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2961 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2962 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2963 os::Linux::numa_available_func_t os::Linux::_numa_available; 2964 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2965 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2966 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2967 unsigned long* os::Linux::_numa_all_nodes; 2968 2969 bool os::pd_uncommit_memory(char* addr, size_t size) { 2970 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2971 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2972 return res != (uintptr_t) MAP_FAILED; 2973 } 2974 2975 static address get_stack_commited_bottom(address bottom, size_t size) { 2976 address nbot = bottom; 2977 address ntop = bottom + size; 2978 2979 size_t page_sz = os::vm_page_size(); 2980 unsigned pages = size / page_sz; 2981 2982 unsigned char vec[1]; 2983 unsigned imin = 1, imax = pages + 1, imid; 2984 int mincore_return_value = 0; 2985 2986 assert(imin <= imax, "Unexpected page size"); 2987 2988 while (imin < imax) { 2989 imid = (imax + imin) / 2; 2990 nbot = ntop - (imid * page_sz); 2991 2992 // Use a trick with mincore to check whether the page is mapped or not. 2993 // mincore sets vec to 1 if page resides in memory and to 0 if page 2994 // is swapped output but if page we are asking for is unmapped 2995 // it returns -1,ENOMEM 2996 mincore_return_value = mincore(nbot, page_sz, vec); 2997 2998 if (mincore_return_value == -1) { 2999 // Page is not mapped go up 3000 // to find first mapped page 3001 if (errno != EAGAIN) { 3002 assert(errno == ENOMEM, "Unexpected mincore errno"); 3003 imax = imid; 3004 } 3005 } else { 3006 // Page is mapped go down 3007 // to find first not mapped page 3008 imin = imid + 1; 3009 } 3010 } 3011 3012 nbot = nbot + page_sz; 3013 3014 // Adjust stack bottom one page up if last checked page is not mapped 3015 if (mincore_return_value == -1) { 3016 nbot = nbot + page_sz; 3017 } 3018 3019 return nbot; 3020 } 3021 3022 3023 // Linux uses a growable mapping for the stack, and if the mapping for 3024 // the stack guard pages is not removed when we detach a thread the 3025 // stack cannot grow beyond the pages where the stack guard was 3026 // mapped. If at some point later in the process the stack expands to 3027 // that point, the Linux kernel cannot expand the stack any further 3028 // because the guard pages are in the way, and a segfault occurs. 3029 // 3030 // However, it's essential not to split the stack region by unmapping 3031 // a region (leaving a hole) that's already part of the stack mapping, 3032 // so if the stack mapping has already grown beyond the guard pages at 3033 // the time we create them, we have to truncate the stack mapping. 3034 // So, we need to know the extent of the stack mapping when 3035 // create_stack_guard_pages() is called. 3036 3037 // We only need this for stacks that are growable: at the time of 3038 // writing thread stacks don't use growable mappings (i.e. those 3039 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 3040 // only applies to the main thread. 3041 3042 // If the (growable) stack mapping already extends beyond the point 3043 // where we're going to put our guard pages, truncate the mapping at 3044 // that point by munmap()ping it. This ensures that when we later 3045 // munmap() the guard pages we don't leave a hole in the stack 3046 // mapping. This only affects the main/initial thread 3047 3048 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3049 if (os::Linux::is_initial_thread()) { 3050 // As we manually grow stack up to bottom inside create_attached_thread(), 3051 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3052 // we don't need to do anything special. 3053 // Check it first, before calling heavy function. 3054 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3055 unsigned char vec[1]; 3056 3057 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3058 // Fallback to slow path on all errors, including EAGAIN 3059 stack_extent = (uintptr_t) get_stack_commited_bottom( 3060 os::Linux::initial_thread_stack_bottom(), 3061 (size_t)addr - stack_extent); 3062 } 3063 3064 if (stack_extent < (uintptr_t)addr) { 3065 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3066 } 3067 } 3068 3069 return os::commit_memory(addr, size, !ExecMem); 3070 } 3071 3072 // If this is a growable mapping, remove the guard pages entirely by 3073 // munmap()ping them. If not, just call uncommit_memory(). This only 3074 // affects the main/initial thread, but guard against future OS changes 3075 // It's safe to always unmap guard pages for initial thread because we 3076 // always place it right after end of the mapped region 3077 3078 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3079 uintptr_t stack_extent, stack_base; 3080 3081 if (os::Linux::is_initial_thread()) { 3082 return ::munmap(addr, size) == 0; 3083 } 3084 3085 return os::uncommit_memory(addr, size); 3086 } 3087 3088 static address _highest_vm_reserved_address = NULL; 3089 3090 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3091 // at 'requested_addr'. If there are existing memory mappings at the same 3092 // location, however, they will be overwritten. If 'fixed' is false, 3093 // 'requested_addr' is only treated as a hint, the return value may or 3094 // may not start from the requested address. Unlike Linux mmap(), this 3095 // function returns NULL to indicate failure. 3096 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3097 char * addr; 3098 int flags; 3099 3100 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3101 if (fixed) { 3102 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3103 flags |= MAP_FIXED; 3104 } 3105 3106 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3107 // touch an uncommitted page. Otherwise, the read/write might 3108 // succeed if we have enough swap space to back the physical page. 3109 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3110 flags, -1, 0); 3111 3112 if (addr != MAP_FAILED) { 3113 // anon_mmap() should only get called during VM initialization, 3114 // don't need lock (actually we can skip locking even it can be called 3115 // from multiple threads, because _highest_vm_reserved_address is just a 3116 // hint about the upper limit of non-stack memory regions.) 3117 if ((address)addr + bytes > _highest_vm_reserved_address) { 3118 _highest_vm_reserved_address = (address)addr + bytes; 3119 } 3120 } 3121 3122 return addr == MAP_FAILED ? NULL : addr; 3123 } 3124 3125 // Don't update _highest_vm_reserved_address, because there might be memory 3126 // regions above addr + size. If so, releasing a memory region only creates 3127 // a hole in the address space, it doesn't help prevent heap-stack collision. 3128 // 3129 static int anon_munmap(char * addr, size_t size) { 3130 return ::munmap(addr, size) == 0; 3131 } 3132 3133 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3134 size_t alignment_hint) { 3135 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3136 } 3137 3138 bool os::pd_release_memory(char* addr, size_t size) { 3139 return anon_munmap(addr, size); 3140 } 3141 3142 static address highest_vm_reserved_address() { 3143 return _highest_vm_reserved_address; 3144 } 3145 3146 static bool linux_mprotect(char* addr, size_t size, int prot) { 3147 // Linux wants the mprotect address argument to be page aligned. 3148 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3149 3150 // According to SUSv3, mprotect() should only be used with mappings 3151 // established by mmap(), and mmap() always maps whole pages. Unaligned 3152 // 'addr' likely indicates problem in the VM (e.g. trying to change 3153 // protection of malloc'ed or statically allocated memory). Check the 3154 // caller if you hit this assert. 3155 assert(addr == bottom, "sanity check"); 3156 3157 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3158 return ::mprotect(bottom, size, prot) == 0; 3159 } 3160 3161 // Set protections specified 3162 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3163 bool is_committed) { 3164 unsigned int p = 0; 3165 switch (prot) { 3166 case MEM_PROT_NONE: p = PROT_NONE; break; 3167 case MEM_PROT_READ: p = PROT_READ; break; 3168 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3169 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3170 default: 3171 ShouldNotReachHere(); 3172 } 3173 // is_committed is unused. 3174 return linux_mprotect(addr, bytes, p); 3175 } 3176 3177 bool os::guard_memory(char* addr, size_t size) { 3178 return linux_mprotect(addr, size, PROT_NONE); 3179 } 3180 3181 bool os::unguard_memory(char* addr, size_t size) { 3182 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3183 } 3184 3185 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, 3186 size_t page_size) { 3187 bool result = false; 3188 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3189 MAP_ANONYMOUS|MAP_PRIVATE, 3190 -1, 0); 3191 if (p != MAP_FAILED) { 3192 void *aligned_p = align_ptr_up(p, page_size); 3193 3194 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3195 3196 munmap(p, page_size * 2); 3197 } 3198 3199 if (warn && !result) { 3200 warning("TransparentHugePages is not supported by the operating system."); 3201 } 3202 3203 return result; 3204 } 3205 3206 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3207 bool result = false; 3208 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3209 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3210 -1, 0); 3211 3212 if (p != MAP_FAILED) { 3213 // We don't know if this really is a huge page or not. 3214 FILE *fp = fopen("/proc/self/maps", "r"); 3215 if (fp) { 3216 while (!feof(fp)) { 3217 char chars[257]; 3218 long x = 0; 3219 if (fgets(chars, sizeof(chars), fp)) { 3220 if (sscanf(chars, "%lx-%*x", &x) == 1 3221 && x == (long)p) { 3222 if (strstr (chars, "hugepage")) { 3223 result = true; 3224 break; 3225 } 3226 } 3227 } 3228 } 3229 fclose(fp); 3230 } 3231 munmap(p, page_size); 3232 } 3233 3234 if (warn && !result) { 3235 warning("HugeTLBFS is not supported by the operating system."); 3236 } 3237 3238 return result; 3239 } 3240 3241 // Set the coredump_filter bits to include largepages in core dump (bit 6) 3242 // 3243 // From the coredump_filter documentation: 3244 // 3245 // - (bit 0) anonymous private memory 3246 // - (bit 1) anonymous shared memory 3247 // - (bit 2) file-backed private memory 3248 // - (bit 3) file-backed shared memory 3249 // - (bit 4) ELF header pages in file-backed private memory areas (it is 3250 // effective only if the bit 2 is cleared) 3251 // - (bit 5) hugetlb private memory 3252 // - (bit 6) hugetlb shared memory 3253 // 3254 static void set_coredump_filter(void) { 3255 FILE *f; 3256 long cdm; 3257 3258 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3259 return; 3260 } 3261 3262 if (fscanf(f, "%lx", &cdm) != 1) { 3263 fclose(f); 3264 return; 3265 } 3266 3267 rewind(f); 3268 3269 if ((cdm & LARGEPAGES_BIT) == 0) { 3270 cdm |= LARGEPAGES_BIT; 3271 fprintf(f, "%#lx", cdm); 3272 } 3273 3274 fclose(f); 3275 } 3276 3277 // Large page support 3278 3279 static size_t _large_page_size = 0; 3280 3281 size_t os::Linux::find_large_page_size() { 3282 size_t large_page_size = 0; 3283 3284 // large_page_size on Linux is used to round up heap size. x86 uses either 3285 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3286 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3287 // page as large as 256M. 3288 // 3289 // Here we try to figure out page size by parsing /proc/meminfo and looking 3290 // for a line with the following format: 3291 // Hugepagesize: 2048 kB 3292 // 3293 // If we can't determine the value (e.g. /proc is not mounted, or the text 3294 // format has been changed), we'll use the largest page size supported by 3295 // the processor. 3296 3297 #ifndef ZERO 3298 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3299 ARM_ONLY(2 * M) PPC_ONLY(4 * M) AARCH64_ONLY(2 * M); 3300 #endif // ZERO 3301 3302 FILE *fp = fopen("/proc/meminfo", "r"); 3303 if (fp) { 3304 while (!feof(fp)) { 3305 int x = 0; 3306 char buf[16]; 3307 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3308 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3309 large_page_size = x * K; 3310 break; 3311 } 3312 } else { 3313 // skip to next line 3314 for (;;) { 3315 int ch = fgetc(fp); 3316 if (ch == EOF || ch == (int)'\n') break; 3317 } 3318 } 3319 } 3320 fclose(fp); 3321 } 3322 3323 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3324 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3325 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3326 proper_unit_for_byte_size(large_page_size)); 3327 } 3328 3329 return large_page_size; 3330 } 3331 3332 size_t os::Linux::setup_large_page_size() { 3333 _large_page_size = Linux::find_large_page_size(); 3334 const size_t default_page_size = (size_t)Linux::page_size(); 3335 if (_large_page_size > default_page_size) { 3336 _page_sizes[0] = _large_page_size; 3337 _page_sizes[1] = default_page_size; 3338 _page_sizes[2] = 0; 3339 } 3340 3341 return _large_page_size; 3342 } 3343 3344 bool os::Linux::setup_large_page_type(size_t page_size) { 3345 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3346 FLAG_IS_DEFAULT(UseSHM) && 3347 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3348 3349 // The type of large pages has not been specified by the user. 3350 3351 // Try UseHugeTLBFS and then UseSHM. 3352 UseHugeTLBFS = UseSHM = true; 3353 3354 // Don't try UseTransparentHugePages since there are known 3355 // performance issues with it turned on. This might change in the future. 3356 UseTransparentHugePages = false; 3357 } 3358 3359 if (UseTransparentHugePages) { 3360 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3361 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3362 UseHugeTLBFS = false; 3363 UseSHM = false; 3364 return true; 3365 } 3366 UseTransparentHugePages = false; 3367 } 3368 3369 if (UseHugeTLBFS) { 3370 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3371 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3372 UseSHM = false; 3373 return true; 3374 } 3375 UseHugeTLBFS = false; 3376 } 3377 3378 return UseSHM; 3379 } 3380 3381 void os::large_page_init() { 3382 if (!UseLargePages && 3383 !UseTransparentHugePages && 3384 !UseHugeTLBFS && 3385 !UseSHM) { 3386 // Not using large pages. 3387 return; 3388 } 3389 3390 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3391 // The user explicitly turned off large pages. 3392 // Ignore the rest of the large pages flags. 3393 UseTransparentHugePages = false; 3394 UseHugeTLBFS = false; 3395 UseSHM = false; 3396 return; 3397 } 3398 3399 size_t large_page_size = Linux::setup_large_page_size(); 3400 UseLargePages = Linux::setup_large_page_type(large_page_size); 3401 3402 set_coredump_filter(); 3403 } 3404 3405 #ifndef SHM_HUGETLB 3406 #define SHM_HUGETLB 04000 3407 #endif 3408 3409 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, 3410 char* req_addr, bool exec) { 3411 // "exec" is passed in but not used. Creating the shared image for 3412 // the code cache doesn't have an SHM_X executable permission to check. 3413 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3414 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3415 3416 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3417 return NULL; // Fallback to small pages. 3418 } 3419 3420 key_t key = IPC_PRIVATE; 3421 char *addr; 3422 3423 bool warn_on_failure = UseLargePages && 3424 (!FLAG_IS_DEFAULT(UseLargePages) || 3425 !FLAG_IS_DEFAULT(UseSHM) || 3426 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3427 char msg[128]; 3428 3429 // Create a large shared memory region to attach to based on size. 3430 // Currently, size is the total size of the heap 3431 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3432 if (shmid == -1) { 3433 // Possible reasons for shmget failure: 3434 // 1. shmmax is too small for Java heap. 3435 // > check shmmax value: cat /proc/sys/kernel/shmmax 3436 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3437 // 2. not enough large page memory. 3438 // > check available large pages: cat /proc/meminfo 3439 // > increase amount of large pages: 3440 // echo new_value > /proc/sys/vm/nr_hugepages 3441 // Note 1: different Linux may use different name for this property, 3442 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3443 // Note 2: it's possible there's enough physical memory available but 3444 // they are so fragmented after a long run that they can't 3445 // coalesce into large pages. Try to reserve large pages when 3446 // the system is still "fresh". 3447 if (warn_on_failure) { 3448 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3449 warning("%s", msg); 3450 } 3451 return NULL; 3452 } 3453 3454 // attach to the region 3455 addr = (char*)shmat(shmid, req_addr, 0); 3456 int err = errno; 3457 3458 // Remove shmid. If shmat() is successful, the actual shared memory segment 3459 // will be deleted when it's detached by shmdt() or when the process 3460 // terminates. If shmat() is not successful this will remove the shared 3461 // segment immediately. 3462 shmctl(shmid, IPC_RMID, NULL); 3463 3464 if ((intptr_t)addr == -1) { 3465 if (warn_on_failure) { 3466 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3467 warning("%s", msg); 3468 } 3469 return NULL; 3470 } 3471 3472 return addr; 3473 } 3474 3475 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, 3476 int error) { 3477 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3478 3479 bool warn_on_failure = UseLargePages && 3480 (!FLAG_IS_DEFAULT(UseLargePages) || 3481 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3482 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3483 3484 if (warn_on_failure) { 3485 char msg[128]; 3486 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3487 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3488 warning("%s", msg); 3489 } 3490 } 3491 3492 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, 3493 char* req_addr, 3494 bool exec) { 3495 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3496 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3497 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3498 3499 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3500 char* addr = (char*)::mmap(req_addr, bytes, prot, 3501 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3502 -1, 0); 3503 3504 if (addr == MAP_FAILED) { 3505 warn_on_large_pages_failure(req_addr, bytes, errno); 3506 return NULL; 3507 } 3508 3509 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3510 3511 return addr; 3512 } 3513 3514 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, 3515 size_t alignment, 3516 char* req_addr, 3517 bool exec) { 3518 size_t large_page_size = os::large_page_size(); 3519 3520 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3521 3522 // Allocate small pages. 3523 3524 char* start; 3525 if (req_addr != NULL) { 3526 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3527 assert(is_size_aligned(bytes, alignment), "Must be"); 3528 start = os::reserve_memory(bytes, req_addr); 3529 assert(start == NULL || start == req_addr, "Must be"); 3530 } else { 3531 start = os::reserve_memory_aligned(bytes, alignment); 3532 } 3533 3534 if (start == NULL) { 3535 return NULL; 3536 } 3537 3538 assert(is_ptr_aligned(start, alignment), "Must be"); 3539 3540 if (MemTracker::tracking_level() > NMT_minimal) { 3541 // os::reserve_memory_special will record this memory area. 3542 // Need to release it here to prevent overlapping reservations. 3543 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3544 tkr.record((address)start, bytes); 3545 } 3546 3547 char* end = start + bytes; 3548 3549 // Find the regions of the allocated chunk that can be promoted to large pages. 3550 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3551 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3552 3553 size_t lp_bytes = lp_end - lp_start; 3554 3555 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3556 3557 if (lp_bytes == 0) { 3558 // The mapped region doesn't even span the start and the end of a large page. 3559 // Fall back to allocate a non-special area. 3560 ::munmap(start, end - start); 3561 return NULL; 3562 } 3563 3564 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3565 3566 3567 void* result; 3568 3569 if (start != lp_start) { 3570 result = ::mmap(start, lp_start - start, prot, 3571 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3572 -1, 0); 3573 if (result == MAP_FAILED) { 3574 ::munmap(lp_start, end - lp_start); 3575 return NULL; 3576 } 3577 } 3578 3579 result = ::mmap(lp_start, lp_bytes, prot, 3580 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3581 -1, 0); 3582 if (result == MAP_FAILED) { 3583 warn_on_large_pages_failure(req_addr, bytes, errno); 3584 // If the mmap above fails, the large pages region will be unmapped and we 3585 // have regions before and after with small pages. Release these regions. 3586 // 3587 // | mapped | unmapped | mapped | 3588 // ^ ^ ^ ^ 3589 // start lp_start lp_end end 3590 // 3591 ::munmap(start, lp_start - start); 3592 ::munmap(lp_end, end - lp_end); 3593 return NULL; 3594 } 3595 3596 if (lp_end != end) { 3597 result = ::mmap(lp_end, end - lp_end, prot, 3598 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3599 -1, 0); 3600 if (result == MAP_FAILED) { 3601 ::munmap(start, lp_end - start); 3602 return NULL; 3603 } 3604 } 3605 3606 return start; 3607 } 3608 3609 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, 3610 size_t alignment, 3611 char* req_addr, 3612 bool exec) { 3613 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3614 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3615 assert(is_power_of_2(alignment), "Must be"); 3616 assert(is_power_of_2(os::large_page_size()), "Must be"); 3617 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3618 3619 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3620 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3621 } else { 3622 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3623 } 3624 } 3625 3626 char* os::reserve_memory_special(size_t bytes, size_t alignment, 3627 char* req_addr, bool exec) { 3628 assert(UseLargePages, "only for large pages"); 3629 3630 char* addr; 3631 if (UseSHM) { 3632 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3633 } else { 3634 assert(UseHugeTLBFS, "must be"); 3635 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3636 } 3637 3638 if (addr != NULL) { 3639 if (UseNUMAInterleaving) { 3640 numa_make_global(addr, bytes); 3641 } 3642 3643 // The memory is committed 3644 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC); 3645 } 3646 3647 return addr; 3648 } 3649 3650 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3651 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3652 return shmdt(base) == 0; 3653 } 3654 3655 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3656 return pd_release_memory(base, bytes); 3657 } 3658 3659 bool os::release_memory_special(char* base, size_t bytes) { 3660 bool res; 3661 if (MemTracker::tracking_level() > NMT_minimal) { 3662 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3663 res = os::Linux::release_memory_special_impl(base, bytes); 3664 if (res) { 3665 tkr.record((address)base, bytes); 3666 } 3667 3668 } else { 3669 res = os::Linux::release_memory_special_impl(base, bytes); 3670 } 3671 return res; 3672 } 3673 3674 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) { 3675 assert(UseLargePages, "only for large pages"); 3676 bool res; 3677 3678 if (UseSHM) { 3679 res = os::Linux::release_memory_special_shm(base, bytes); 3680 } else { 3681 assert(UseHugeTLBFS, "must be"); 3682 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3683 } 3684 return res; 3685 } 3686 3687 size_t os::large_page_size() { 3688 return _large_page_size; 3689 } 3690 3691 // With SysV SHM the entire memory region must be allocated as shared 3692 // memory. 3693 // HugeTLBFS allows application to commit large page memory on demand. 3694 // However, when committing memory with HugeTLBFS fails, the region 3695 // that was supposed to be committed will lose the old reservation 3696 // and allow other threads to steal that memory region. Because of this 3697 // behavior we can't commit HugeTLBFS memory. 3698 bool os::can_commit_large_page_memory() { 3699 return UseTransparentHugePages; 3700 } 3701 3702 bool os::can_execute_large_page_memory() { 3703 return UseTransparentHugePages || UseHugeTLBFS; 3704 } 3705 3706 // Reserve memory at an arbitrary address, only if that area is 3707 // available (and not reserved for something else). 3708 3709 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3710 const int max_tries = 10; 3711 char* base[max_tries]; 3712 size_t size[max_tries]; 3713 const size_t gap = 0x000000; 3714 3715 // Assert only that the size is a multiple of the page size, since 3716 // that's all that mmap requires, and since that's all we really know 3717 // about at this low abstraction level. If we need higher alignment, 3718 // we can either pass an alignment to this method or verify alignment 3719 // in one of the methods further up the call chain. See bug 5044738. 3720 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3721 3722 // Repeatedly allocate blocks until the block is allocated at the 3723 // right spot. Give up after max_tries. Note that reserve_memory() will 3724 // automatically update _highest_vm_reserved_address if the call is 3725 // successful. The variable tracks the highest memory address every reserved 3726 // by JVM. It is used to detect heap-stack collision if running with 3727 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3728 // space than needed, it could confuse the collision detecting code. To 3729 // solve the problem, save current _highest_vm_reserved_address and 3730 // calculate the correct value before return. 3731 address old_highest = _highest_vm_reserved_address; 3732 3733 // Linux mmap allows caller to pass an address as hint; give it a try first, 3734 // if kernel honors the hint then we can return immediately. 3735 char * addr = anon_mmap(requested_addr, bytes, false); 3736 if (addr == requested_addr) { 3737 return requested_addr; 3738 } 3739 3740 if (addr != NULL) { 3741 // mmap() is successful but it fails to reserve at the requested address 3742 anon_munmap(addr, bytes); 3743 } 3744 3745 int i; 3746 for (i = 0; i < max_tries; ++i) { 3747 base[i] = reserve_memory(bytes); 3748 3749 if (base[i] != NULL) { 3750 // Is this the block we wanted? 3751 if (base[i] == requested_addr) { 3752 size[i] = bytes; 3753 break; 3754 } 3755 3756 // Does this overlap the block we wanted? Give back the overlapped 3757 // parts and try again. 3758 3759 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3760 if (top_overlap >= 0 && top_overlap < bytes) { 3761 unmap_memory(base[i], top_overlap); 3762 base[i] += top_overlap; 3763 size[i] = bytes - top_overlap; 3764 } else { 3765 size_t bottom_overlap = base[i] + bytes - requested_addr; 3766 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 3767 unmap_memory(requested_addr, bottom_overlap); 3768 size[i] = bytes - bottom_overlap; 3769 } else { 3770 size[i] = bytes; 3771 } 3772 } 3773 } 3774 } 3775 3776 // Give back the unused reserved pieces. 3777 3778 for (int j = 0; j < i; ++j) { 3779 if (base[j] != NULL) { 3780 unmap_memory(base[j], size[j]); 3781 } 3782 } 3783 3784 if (i < max_tries) { 3785 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3786 return requested_addr; 3787 } else { 3788 _highest_vm_reserved_address = old_highest; 3789 return NULL; 3790 } 3791 } 3792 3793 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3794 return ::read(fd, buf, nBytes); 3795 } 3796 3797 size_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) { 3798 return ::pread(fd, buf, nBytes, offset); 3799 } 3800 3801 // Short sleep, direct OS call. 3802 // 3803 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee 3804 // sched_yield(2) will actually give up the CPU: 3805 // 3806 // * Alone on this pariticular CPU, keeps running. 3807 // * Before the introduction of "skip_buddy" with "compat_yield" disabled 3808 // (pre 2.6.39). 3809 // 3810 // So calling this with 0 is an alternative. 3811 // 3812 void os::naked_short_sleep(jlong ms) { 3813 struct timespec req; 3814 3815 assert(ms < 1000, "Un-interruptable sleep, short time use only"); 3816 req.tv_sec = 0; 3817 if (ms > 0) { 3818 req.tv_nsec = (ms % 1000) * 1000000; 3819 } else { 3820 req.tv_nsec = 1; 3821 } 3822 3823 nanosleep(&req, NULL); 3824 3825 return; 3826 } 3827 3828 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3829 void os::infinite_sleep() { 3830 while (true) { // sleep forever ... 3831 ::sleep(100); // ... 100 seconds at a time 3832 } 3833 } 3834 3835 // Used to convert frequent JVM_Yield() to nops 3836 bool os::dont_yield() { 3837 return DontYieldALot; 3838 } 3839 3840 void os::naked_yield() { 3841 sched_yield(); 3842 } 3843 3844 //////////////////////////////////////////////////////////////////////////////// 3845 // thread priority support 3846 3847 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3848 // only supports dynamic priority, static priority must be zero. For real-time 3849 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3850 // However, for large multi-threaded applications, SCHED_RR is not only slower 3851 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3852 // of 5 runs - Sep 2005). 3853 // 3854 // The following code actually changes the niceness of kernel-thread/LWP. It 3855 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3856 // not the entire user process, and user level threads are 1:1 mapped to kernel 3857 // threads. It has always been the case, but could change in the future. For 3858 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3859 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3860 3861 int os::java_to_os_priority[CriticalPriority + 1] = { 3862 19, // 0 Entry should never be used 3863 3864 4, // 1 MinPriority 3865 3, // 2 3866 2, // 3 3867 3868 1, // 4 3869 0, // 5 NormPriority 3870 -1, // 6 3871 3872 -2, // 7 3873 -3, // 8 3874 -4, // 9 NearMaxPriority 3875 3876 -5, // 10 MaxPriority 3877 3878 -5 // 11 CriticalPriority 3879 }; 3880 3881 static int prio_init() { 3882 if (ThreadPriorityPolicy == 1) { 3883 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3884 // if effective uid is not root. Perhaps, a more elegant way of doing 3885 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3886 if (geteuid() != 0) { 3887 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3888 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3889 } 3890 ThreadPriorityPolicy = 0; 3891 } 3892 } 3893 if (UseCriticalJavaThreadPriority) { 3894 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3895 } 3896 return 0; 3897 } 3898 3899 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3900 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK; 3901 3902 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3903 return (ret == 0) ? OS_OK : OS_ERR; 3904 } 3905 3906 OSReturn os::get_native_priority(const Thread* const thread, 3907 int *priority_ptr) { 3908 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) { 3909 *priority_ptr = java_to_os_priority[NormPriority]; 3910 return OS_OK; 3911 } 3912 3913 errno = 0; 3914 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3915 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3916 } 3917 3918 // Hint to the underlying OS that a task switch would not be good. 3919 // Void return because it's a hint and can fail. 3920 void os::hint_no_preempt() {} 3921 3922 //////////////////////////////////////////////////////////////////////////////// 3923 // suspend/resume support 3924 3925 // the low-level signal-based suspend/resume support is a remnant from the 3926 // old VM-suspension that used to be for java-suspension, safepoints etc, 3927 // within hotspot. Now there is a single use-case for this: 3928 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3929 // that runs in the watcher thread. 3930 // The remaining code is greatly simplified from the more general suspension 3931 // code that used to be used. 3932 // 3933 // The protocol is quite simple: 3934 // - suspend: 3935 // - sends a signal to the target thread 3936 // - polls the suspend state of the osthread using a yield loop 3937 // - target thread signal handler (SR_handler) sets suspend state 3938 // and blocks in sigsuspend until continued 3939 // - resume: 3940 // - sets target osthread state to continue 3941 // - sends signal to end the sigsuspend loop in the SR_handler 3942 // 3943 // Note that the SR_lock plays no role in this suspend/resume protocol. 3944 3945 static void resume_clear_context(OSThread *osthread) { 3946 osthread->set_ucontext(NULL); 3947 osthread->set_siginfo(NULL); 3948 } 3949 3950 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, 3951 ucontext_t* context) { 3952 osthread->set_ucontext(context); 3953 osthread->set_siginfo(siginfo); 3954 } 3955 3956 // Handler function invoked when a thread's execution is suspended or 3957 // resumed. We have to be careful that only async-safe functions are 3958 // called here (Note: most pthread functions are not async safe and 3959 // should be avoided.) 3960 // 3961 // Note: sigwait() is a more natural fit than sigsuspend() from an 3962 // interface point of view, but sigwait() prevents the signal hander 3963 // from being run. libpthread would get very confused by not having 3964 // its signal handlers run and prevents sigwait()'s use with the 3965 // mutex granting granting signal. 3966 // 3967 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 3968 // 3969 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3970 // Save and restore errno to avoid confusing native code with EINTR 3971 // after sigsuspend. 3972 int old_errno = errno; 3973 3974 Thread* thread = Thread::current(); 3975 OSThread* osthread = thread->osthread(); 3976 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 3977 3978 os::SuspendResume::State current = osthread->sr.state(); 3979 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 3980 suspend_save_context(osthread, siginfo, context); 3981 3982 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 3983 os::SuspendResume::State state = osthread->sr.suspended(); 3984 if (state == os::SuspendResume::SR_SUSPENDED) { 3985 sigset_t suspend_set; // signals for sigsuspend() 3986 3987 // get current set of blocked signals and unblock resume signal 3988 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3989 sigdelset(&suspend_set, SR_signum); 3990 3991 sr_semaphore.signal(); 3992 // wait here until we are resumed 3993 while (1) { 3994 sigsuspend(&suspend_set); 3995 3996 os::SuspendResume::State result = osthread->sr.running(); 3997 if (result == os::SuspendResume::SR_RUNNING) { 3998 sr_semaphore.signal(); 3999 break; 4000 } 4001 } 4002 4003 } else if (state == os::SuspendResume::SR_RUNNING) { 4004 // request was cancelled, continue 4005 } else { 4006 ShouldNotReachHere(); 4007 } 4008 4009 resume_clear_context(osthread); 4010 } else if (current == os::SuspendResume::SR_RUNNING) { 4011 // request was cancelled, continue 4012 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 4013 // ignore 4014 } else { 4015 // ignore 4016 } 4017 4018 errno = old_errno; 4019 } 4020 4021 4022 static int SR_initialize() { 4023 struct sigaction act; 4024 char *s; 4025 // Get signal number to use for suspend/resume 4026 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 4027 int sig = ::strtol(s, 0, 10); 4028 if (sig > 0 || sig < _NSIG) { 4029 SR_signum = sig; 4030 } 4031 } 4032 4033 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 4034 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 4035 4036 sigemptyset(&SR_sigset); 4037 sigaddset(&SR_sigset, SR_signum); 4038 4039 // Set up signal handler for suspend/resume 4040 act.sa_flags = SA_RESTART|SA_SIGINFO; 4041 act.sa_handler = (void (*)(int)) SR_handler; 4042 4043 // SR_signum is blocked by default. 4044 // 4528190 - We also need to block pthread restart signal (32 on all 4045 // supported Linux platforms). Note that LinuxThreads need to block 4046 // this signal for all threads to work properly. So we don't have 4047 // to use hard-coded signal number when setting up the mask. 4048 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4049 4050 if (sigaction(SR_signum, &act, 0) == -1) { 4051 return -1; 4052 } 4053 4054 // Save signal flag 4055 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4056 return 0; 4057 } 4058 4059 static int sr_notify(OSThread* osthread) { 4060 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4061 assert_status(status == 0, status, "pthread_kill"); 4062 return status; 4063 } 4064 4065 // "Randomly" selected value for how long we want to spin 4066 // before bailing out on suspending a thread, also how often 4067 // we send a signal to a thread we want to resume 4068 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4069 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4070 4071 // returns true on success and false on error - really an error is fatal 4072 // but this seems the normal response to library errors 4073 static bool do_suspend(OSThread* osthread) { 4074 assert(osthread->sr.is_running(), "thread should be running"); 4075 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4076 4077 // mark as suspended and send signal 4078 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4079 // failed to switch, state wasn't running? 4080 ShouldNotReachHere(); 4081 return false; 4082 } 4083 4084 if (sr_notify(osthread) != 0) { 4085 ShouldNotReachHere(); 4086 } 4087 4088 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4089 while (true) { 4090 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4091 break; 4092 } else { 4093 // timeout 4094 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4095 if (cancelled == os::SuspendResume::SR_RUNNING) { 4096 return false; 4097 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4098 // make sure that we consume the signal on the semaphore as well 4099 sr_semaphore.wait(); 4100 break; 4101 } else { 4102 ShouldNotReachHere(); 4103 return false; 4104 } 4105 } 4106 } 4107 4108 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4109 return true; 4110 } 4111 4112 static void do_resume(OSThread* osthread) { 4113 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4114 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4115 4116 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4117 // failed to switch to WAKEUP_REQUEST 4118 ShouldNotReachHere(); 4119 return; 4120 } 4121 4122 while (true) { 4123 if (sr_notify(osthread) == 0) { 4124 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4125 if (osthread->sr.is_running()) { 4126 return; 4127 } 4128 } 4129 } else { 4130 ShouldNotReachHere(); 4131 } 4132 } 4133 4134 guarantee(osthread->sr.is_running(), "Must be running!"); 4135 } 4136 4137 /////////////////////////////////////////////////////////////////////////////////// 4138 // signal handling (except suspend/resume) 4139 4140 // This routine may be used by user applications as a "hook" to catch signals. 4141 // The user-defined signal handler must pass unrecognized signals to this 4142 // routine, and if it returns true (non-zero), then the signal handler must 4143 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4144 // routine will never retun false (zero), but instead will execute a VM panic 4145 // routine kill the process. 4146 // 4147 // If this routine returns false, it is OK to call it again. This allows 4148 // the user-defined signal handler to perform checks either before or after 4149 // the VM performs its own checks. Naturally, the user code would be making 4150 // a serious error if it tried to handle an exception (such as a null check 4151 // or breakpoint) that the VM was generating for its own correct operation. 4152 // 4153 // This routine may recognize any of the following kinds of signals: 4154 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4155 // It should be consulted by handlers for any of those signals. 4156 // 4157 // The caller of this routine must pass in the three arguments supplied 4158 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4159 // field of the structure passed to sigaction(). This routine assumes that 4160 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4161 // 4162 // Note that the VM will print warnings if it detects conflicting signal 4163 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4164 // 4165 extern "C" JNIEXPORT int JVM_handle_linux_signal(int signo, 4166 siginfo_t* siginfo, 4167 void* ucontext, 4168 int abort_if_unrecognized); 4169 4170 void signalHandler(int sig, siginfo_t* info, void* uc) { 4171 assert(info != NULL && uc != NULL, "it must be old kernel"); 4172 int orig_errno = errno; // Preserve errno value over signal handler. 4173 JVM_handle_linux_signal(sig, info, uc, true); 4174 errno = orig_errno; 4175 } 4176 4177 4178 // This boolean allows users to forward their own non-matching signals 4179 // to JVM_handle_linux_signal, harmlessly. 4180 bool os::Linux::signal_handlers_are_installed = false; 4181 4182 // For signal-chaining 4183 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4184 unsigned int os::Linux::sigs = 0; 4185 bool os::Linux::libjsig_is_loaded = false; 4186 typedef struct sigaction *(*get_signal_t)(int); 4187 get_signal_t os::Linux::get_signal_action = NULL; 4188 4189 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4190 struct sigaction *actp = NULL; 4191 4192 if (libjsig_is_loaded) { 4193 // Retrieve the old signal handler from libjsig 4194 actp = (*get_signal_action)(sig); 4195 } 4196 if (actp == NULL) { 4197 // Retrieve the preinstalled signal handler from jvm 4198 actp = get_preinstalled_handler(sig); 4199 } 4200 4201 return actp; 4202 } 4203 4204 static bool call_chained_handler(struct sigaction *actp, int sig, 4205 siginfo_t *siginfo, void *context) { 4206 // Call the old signal handler 4207 if (actp->sa_handler == SIG_DFL) { 4208 // It's more reasonable to let jvm treat it as an unexpected exception 4209 // instead of taking the default action. 4210 return false; 4211 } else if (actp->sa_handler != SIG_IGN) { 4212 if ((actp->sa_flags & SA_NODEFER) == 0) { 4213 // automaticlly block the signal 4214 sigaddset(&(actp->sa_mask), sig); 4215 } 4216 4217 sa_handler_t hand; 4218 sa_sigaction_t sa; 4219 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4220 // retrieve the chained handler 4221 if (siginfo_flag_set) { 4222 sa = actp->sa_sigaction; 4223 } else { 4224 hand = actp->sa_handler; 4225 } 4226 4227 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4228 actp->sa_handler = SIG_DFL; 4229 } 4230 4231 // try to honor the signal mask 4232 sigset_t oset; 4233 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4234 4235 // call into the chained handler 4236 if (siginfo_flag_set) { 4237 (*sa)(sig, siginfo, context); 4238 } else { 4239 (*hand)(sig); 4240 } 4241 4242 // restore the signal mask 4243 pthread_sigmask(SIG_SETMASK, &oset, 0); 4244 } 4245 // Tell jvm's signal handler the signal is taken care of. 4246 return true; 4247 } 4248 4249 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4250 bool chained = false; 4251 // signal-chaining 4252 if (UseSignalChaining) { 4253 struct sigaction *actp = get_chained_signal_action(sig); 4254 if (actp != NULL) { 4255 chained = call_chained_handler(actp, sig, siginfo, context); 4256 } 4257 } 4258 return chained; 4259 } 4260 4261 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4262 if ((((unsigned int)1 << sig) & sigs) != 0) { 4263 return &sigact[sig]; 4264 } 4265 return NULL; 4266 } 4267 4268 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4269 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4270 sigact[sig] = oldAct; 4271 sigs |= (unsigned int)1 << sig; 4272 } 4273 4274 // for diagnostic 4275 int os::Linux::sigflags[MAXSIGNUM]; 4276 4277 int os::Linux::get_our_sigflags(int sig) { 4278 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4279 return sigflags[sig]; 4280 } 4281 4282 void os::Linux::set_our_sigflags(int sig, int flags) { 4283 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4284 sigflags[sig] = flags; 4285 } 4286 4287 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4288 // Check for overwrite. 4289 struct sigaction oldAct; 4290 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4291 4292 void* oldhand = oldAct.sa_sigaction 4293 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4294 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4295 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4296 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4297 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4298 if (AllowUserSignalHandlers || !set_installed) { 4299 // Do not overwrite; user takes responsibility to forward to us. 4300 return; 4301 } else if (UseSignalChaining) { 4302 // save the old handler in jvm 4303 save_preinstalled_handler(sig, oldAct); 4304 // libjsig also interposes the sigaction() call below and saves the 4305 // old sigaction on it own. 4306 } else { 4307 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4308 "%#lx for signal %d.", (long)oldhand, sig)); 4309 } 4310 } 4311 4312 struct sigaction sigAct; 4313 sigfillset(&(sigAct.sa_mask)); 4314 sigAct.sa_handler = SIG_DFL; 4315 if (!set_installed) { 4316 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4317 } else { 4318 sigAct.sa_sigaction = signalHandler; 4319 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4320 } 4321 // Save flags, which are set by ours 4322 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4323 sigflags[sig] = sigAct.sa_flags; 4324 4325 int ret = sigaction(sig, &sigAct, &oldAct); 4326 assert(ret == 0, "check"); 4327 4328 void* oldhand2 = oldAct.sa_sigaction 4329 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4330 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4331 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4332 } 4333 4334 // install signal handlers for signals that HotSpot needs to 4335 // handle in order to support Java-level exception handling. 4336 4337 void os::Linux::install_signal_handlers() { 4338 if (!signal_handlers_are_installed) { 4339 signal_handlers_are_installed = true; 4340 4341 // signal-chaining 4342 typedef void (*signal_setting_t)(); 4343 signal_setting_t begin_signal_setting = NULL; 4344 signal_setting_t end_signal_setting = NULL; 4345 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4346 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4347 if (begin_signal_setting != NULL) { 4348 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4349 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4350 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4351 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4352 libjsig_is_loaded = true; 4353 assert(UseSignalChaining, "should enable signal-chaining"); 4354 } 4355 if (libjsig_is_loaded) { 4356 // Tell libjsig jvm is setting signal handlers 4357 (*begin_signal_setting)(); 4358 } 4359 4360 set_signal_handler(SIGSEGV, true); 4361 set_signal_handler(SIGPIPE, true); 4362 set_signal_handler(SIGBUS, true); 4363 set_signal_handler(SIGILL, true); 4364 set_signal_handler(SIGFPE, true); 4365 #if defined(PPC64) 4366 set_signal_handler(SIGTRAP, true); 4367 #endif 4368 set_signal_handler(SIGXFSZ, true); 4369 4370 if (libjsig_is_loaded) { 4371 // Tell libjsig jvm finishes setting signal handlers 4372 (*end_signal_setting)(); 4373 } 4374 4375 // We don't activate signal checker if libjsig is in place, we trust ourselves 4376 // and if UserSignalHandler is installed all bets are off. 4377 // Log that signal checking is off only if -verbose:jni is specified. 4378 if (CheckJNICalls) { 4379 if (libjsig_is_loaded) { 4380 if (PrintJNIResolving) { 4381 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4382 } 4383 check_signals = false; 4384 } 4385 if (AllowUserSignalHandlers) { 4386 if (PrintJNIResolving) { 4387 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4388 } 4389 check_signals = false; 4390 } 4391 } 4392 } 4393 } 4394 4395 // This is the fastest way to get thread cpu time on Linux. 4396 // Returns cpu time (user+sys) for any thread, not only for current. 4397 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4398 // It might work on 2.6.10+ with a special kernel/glibc patch. 4399 // For reference, please, see IEEE Std 1003.1-2004: 4400 // http://www.unix.org/single_unix_specification 4401 4402 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4403 struct timespec tp; 4404 int rc = os::Linux::clock_gettime(clockid, &tp); 4405 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4406 4407 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4408 } 4409 4410 ///// 4411 // glibc on Linux platform uses non-documented flag 4412 // to indicate, that some special sort of signal 4413 // trampoline is used. 4414 // We will never set this flag, and we should 4415 // ignore this flag in our diagnostic 4416 #ifdef SIGNIFICANT_SIGNAL_MASK 4417 #undef SIGNIFICANT_SIGNAL_MASK 4418 #endif 4419 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4420 4421 static const char* get_signal_handler_name(address handler, 4422 char* buf, int buflen) { 4423 int offset; 4424 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4425 if (found) { 4426 // skip directory names 4427 const char *p1, *p2; 4428 p1 = buf; 4429 size_t len = strlen(os::file_separator()); 4430 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4431 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4432 } else { 4433 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4434 } 4435 return buf; 4436 } 4437 4438 static void print_signal_handler(outputStream* st, int sig, 4439 char* buf, size_t buflen) { 4440 struct sigaction sa; 4441 4442 sigaction(sig, NULL, &sa); 4443 4444 // See comment for SIGNIFICANT_SIGNAL_MASK define 4445 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4446 4447 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4448 4449 address handler = (sa.sa_flags & SA_SIGINFO) 4450 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4451 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4452 4453 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4454 st->print("SIG_DFL"); 4455 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4456 st->print("SIG_IGN"); 4457 } else { 4458 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4459 } 4460 4461 st->print(", sa_mask[0]="); 4462 os::Posix::print_signal_set_short(st, &sa.sa_mask); 4463 4464 address rh = VMError::get_resetted_sighandler(sig); 4465 // May be, handler was resetted by VMError? 4466 if (rh != NULL) { 4467 handler = rh; 4468 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4469 } 4470 4471 st->print(", sa_flags="); 4472 os::Posix::print_sa_flags(st, sa.sa_flags); 4473 4474 // Check: is it our handler? 4475 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4476 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4477 // It is our signal handler 4478 // check for flags, reset system-used one! 4479 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4480 st->print( 4481 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4482 os::Linux::get_our_sigflags(sig)); 4483 } 4484 } 4485 st->cr(); 4486 } 4487 4488 4489 #define DO_SIGNAL_CHECK(sig) \ 4490 do { \ 4491 if (!sigismember(&check_signal_done, sig)) { \ 4492 os::Linux::check_signal_handler(sig); \ 4493 } \ 4494 } while (0) 4495 4496 // This method is a periodic task to check for misbehaving JNI applications 4497 // under CheckJNI, we can add any periodic checks here 4498 4499 void os::run_periodic_checks() { 4500 if (check_signals == false) return; 4501 4502 // SEGV and BUS if overridden could potentially prevent 4503 // generation of hs*.log in the event of a crash, debugging 4504 // such a case can be very challenging, so we absolutely 4505 // check the following for a good measure: 4506 DO_SIGNAL_CHECK(SIGSEGV); 4507 DO_SIGNAL_CHECK(SIGILL); 4508 DO_SIGNAL_CHECK(SIGFPE); 4509 DO_SIGNAL_CHECK(SIGBUS); 4510 DO_SIGNAL_CHECK(SIGPIPE); 4511 DO_SIGNAL_CHECK(SIGXFSZ); 4512 #if defined(PPC64) 4513 DO_SIGNAL_CHECK(SIGTRAP); 4514 #endif 4515 4516 // ReduceSignalUsage allows the user to override these handlers 4517 // see comments at the very top and jvm_solaris.h 4518 if (!ReduceSignalUsage) { 4519 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4520 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4521 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4522 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4523 } 4524 4525 DO_SIGNAL_CHECK(SR_signum); 4526 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4527 } 4528 4529 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4530 4531 static os_sigaction_t os_sigaction = NULL; 4532 4533 void os::Linux::check_signal_handler(int sig) { 4534 char buf[O_BUFLEN]; 4535 address jvmHandler = NULL; 4536 4537 4538 struct sigaction act; 4539 if (os_sigaction == NULL) { 4540 // only trust the default sigaction, in case it has been interposed 4541 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4542 if (os_sigaction == NULL) return; 4543 } 4544 4545 os_sigaction(sig, (struct sigaction*)NULL, &act); 4546 4547 4548 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4549 4550 address thisHandler = (act.sa_flags & SA_SIGINFO) 4551 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4552 : CAST_FROM_FN_PTR(address, act.sa_handler); 4553 4554 4555 switch (sig) { 4556 case SIGSEGV: 4557 case SIGBUS: 4558 case SIGFPE: 4559 case SIGPIPE: 4560 case SIGILL: 4561 case SIGXFSZ: 4562 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4563 break; 4564 4565 case SHUTDOWN1_SIGNAL: 4566 case SHUTDOWN2_SIGNAL: 4567 case SHUTDOWN3_SIGNAL: 4568 case BREAK_SIGNAL: 4569 jvmHandler = (address)user_handler(); 4570 break; 4571 4572 case INTERRUPT_SIGNAL: 4573 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4574 break; 4575 4576 default: 4577 if (sig == SR_signum) { 4578 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4579 } else { 4580 return; 4581 } 4582 break; 4583 } 4584 4585 if (thisHandler != jvmHandler) { 4586 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4587 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4588 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4589 // No need to check this sig any longer 4590 sigaddset(&check_signal_done, sig); 4591 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN 4592 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) { 4593 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell", 4594 exception_name(sig, buf, O_BUFLEN)); 4595 } 4596 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4597 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4598 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4599 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4600 // No need to check this sig any longer 4601 sigaddset(&check_signal_done, sig); 4602 } 4603 4604 // Dump all the signal 4605 if (sigismember(&check_signal_done, sig)) { 4606 print_signal_handlers(tty, buf, O_BUFLEN); 4607 } 4608 } 4609 4610 extern void report_error(char* file_name, int line_no, char* title, 4611 char* format, ...); 4612 4613 extern bool signal_name(int signo, char* buf, size_t len); 4614 4615 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4616 if (0 < exception_code && exception_code <= SIGRTMAX) { 4617 // signal 4618 if (!signal_name(exception_code, buf, size)) { 4619 jio_snprintf(buf, size, "SIG%d", exception_code); 4620 } 4621 return buf; 4622 } else { 4623 return NULL; 4624 } 4625 } 4626 4627 // this is called _before_ the most of global arguments have been parsed 4628 void os::init(void) { 4629 char dummy; // used to get a guess on initial stack address 4630 // first_hrtime = gethrtime(); 4631 4632 // With LinuxThreads the JavaMain thread pid (primordial thread) 4633 // is different than the pid of the java launcher thread. 4634 // So, on Linux, the launcher thread pid is passed to the VM 4635 // via the sun.java.launcher.pid property. 4636 // Use this property instead of getpid() if it was correctly passed. 4637 // See bug 6351349. 4638 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4639 4640 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4641 4642 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4643 4644 init_random(1234567); 4645 4646 ThreadCritical::initialize(); 4647 4648 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4649 if (Linux::page_size() == -1) { 4650 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4651 strerror(errno))); 4652 } 4653 init_page_sizes((size_t) Linux::page_size()); 4654 4655 Linux::initialize_system_info(); 4656 4657 // main_thread points to the aboriginal thread 4658 Linux::_main_thread = pthread_self(); 4659 4660 Linux::clock_init(); 4661 initial_time_count = javaTimeNanos(); 4662 4663 // pthread_condattr initialization for monotonic clock 4664 int status; 4665 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4666 if ((status = pthread_condattr_init(_condattr)) != 0) { 4667 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4668 } 4669 // Only set the clock if CLOCK_MONOTONIC is available 4670 if (os::supports_monotonic_clock()) { 4671 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4672 if (status == EINVAL) { 4673 warning("Unable to use monotonic clock with relative timed-waits" \ 4674 " - changes to the time-of-day clock may have adverse affects"); 4675 } else { 4676 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4677 } 4678 } 4679 } 4680 // else it defaults to CLOCK_REALTIME 4681 4682 pthread_mutex_init(&dl_mutex, NULL); 4683 4684 // If the pagesize of the VM is greater than 8K determine the appropriate 4685 // number of initial guard pages. The user can change this with the 4686 // command line arguments, if needed. 4687 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4688 StackYellowPages = 1; 4689 StackRedPages = 1; 4690 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4691 } 4692 4693 // retrieve entry point for pthread_setname_np 4694 Linux::_pthread_setname_np = 4695 (int(*)(pthread_t, const char*))dlsym(RTLD_DEFAULT, "pthread_setname_np"); 4696 4697 } 4698 4699 // To install functions for atexit system call 4700 extern "C" { 4701 static void perfMemory_exit_helper() { 4702 perfMemory_exit(); 4703 } 4704 } 4705 4706 // this is called _after_ the global arguments have been parsed 4707 jint os::init_2(void) { 4708 Linux::fast_thread_clock_init(); 4709 4710 // Allocate a single page and mark it as readable for safepoint polling 4711 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4712 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page"); 4713 4714 os::set_polling_page(polling_page); 4715 4716 #ifndef PRODUCT 4717 if (Verbose && PrintMiscellaneous) { 4718 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", 4719 (intptr_t)polling_page); 4720 } 4721 #endif 4722 4723 if (!UseMembar) { 4724 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4725 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4726 os::set_memory_serialize_page(mem_serialize_page); 4727 4728 #ifndef PRODUCT 4729 if (Verbose && PrintMiscellaneous) { 4730 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", 4731 (intptr_t)mem_serialize_page); 4732 } 4733 #endif 4734 } 4735 4736 // initialize suspend/resume support - must do this before signal_sets_init() 4737 if (SR_initialize() != 0) { 4738 perror("SR_initialize failed"); 4739 return JNI_ERR; 4740 } 4741 4742 Linux::signal_sets_init(); 4743 Linux::install_signal_handlers(); 4744 4745 // Check minimum allowable stack size for thread creation and to initialize 4746 // the java system classes, including StackOverflowError - depends on page 4747 // size. Add a page for compiler2 recursion in main thread. 4748 // Add in 2*BytesPerWord times page size to account for VM stack during 4749 // class initialization depending on 32 or 64 bit VM. 4750 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4751 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4752 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4753 4754 size_t threadStackSizeInBytes = ThreadStackSize * K; 4755 if (threadStackSizeInBytes != 0 && 4756 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4757 tty->print_cr("\nThe stack size specified is too small, " 4758 "Specify at least %dk", 4759 os::Linux::min_stack_allowed/ K); 4760 return JNI_ERR; 4761 } 4762 4763 // Make the stack size a multiple of the page size so that 4764 // the yellow/red zones can be guarded. 4765 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4766 vm_page_size())); 4767 4768 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4769 4770 #if defined(IA32) 4771 workaround_expand_exec_shield_cs_limit(); 4772 #endif 4773 4774 Linux::libpthread_init(); 4775 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4776 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4777 Linux::glibc_version(), Linux::libpthread_version(), 4778 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4779 } 4780 4781 if (UseNUMA) { 4782 if (!Linux::libnuma_init()) { 4783 UseNUMA = false; 4784 } else { 4785 if ((Linux::numa_max_node() < 1)) { 4786 // There's only one node(they start from 0), disable NUMA. 4787 UseNUMA = false; 4788 } 4789 } 4790 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4791 // we can make the adaptive lgrp chunk resizing work. If the user specified 4792 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4793 // disable adaptive resizing. 4794 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4795 if (FLAG_IS_DEFAULT(UseNUMA)) { 4796 UseNUMA = false; 4797 } else { 4798 if (FLAG_IS_DEFAULT(UseLargePages) && 4799 FLAG_IS_DEFAULT(UseSHM) && 4800 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4801 UseLargePages = false; 4802 } else { 4803 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4804 UseAdaptiveSizePolicy = false; 4805 UseAdaptiveNUMAChunkSizing = false; 4806 } 4807 } 4808 } 4809 if (!UseNUMA && ForceNUMA) { 4810 UseNUMA = true; 4811 } 4812 } 4813 4814 if (MaxFDLimit) { 4815 // set the number of file descriptors to max. print out error 4816 // if getrlimit/setrlimit fails but continue regardless. 4817 struct rlimit nbr_files; 4818 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4819 if (status != 0) { 4820 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4821 perror("os::init_2 getrlimit failed"); 4822 } 4823 } else { 4824 nbr_files.rlim_cur = nbr_files.rlim_max; 4825 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4826 if (status != 0) { 4827 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4828 perror("os::init_2 setrlimit failed"); 4829 } 4830 } 4831 } 4832 } 4833 4834 // Initialize lock used to serialize thread creation (see os::create_thread) 4835 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4836 4837 // at-exit methods are called in the reverse order of their registration. 4838 // atexit functions are called on return from main or as a result of a 4839 // call to exit(3C). There can be only 32 of these functions registered 4840 // and atexit() does not set errno. 4841 4842 if (PerfAllowAtExitRegistration) { 4843 // only register atexit functions if PerfAllowAtExitRegistration is set. 4844 // atexit functions can be delayed until process exit time, which 4845 // can be problematic for embedded VM situations. Embedded VMs should 4846 // call DestroyJavaVM() to assure that VM resources are released. 4847 4848 // note: perfMemory_exit_helper atexit function may be removed in 4849 // the future if the appropriate cleanup code can be added to the 4850 // VM_Exit VMOperation's doit method. 4851 if (atexit(perfMemory_exit_helper) != 0) { 4852 warning("os::init_2 atexit(perfMemory_exit_helper) failed"); 4853 } 4854 } 4855 4856 // initialize thread priority policy 4857 prio_init(); 4858 4859 return JNI_OK; 4860 } 4861 4862 // Mark the polling page as unreadable 4863 void os::make_polling_page_unreadable(void) { 4864 if (!guard_memory((char*)_polling_page, Linux::page_size())) { 4865 fatal("Could not disable polling page"); 4866 } 4867 } 4868 4869 // Mark the polling page as readable 4870 void os::make_polling_page_readable(void) { 4871 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4872 fatal("Could not enable polling page"); 4873 } 4874 } 4875 4876 int os::active_processor_count() { 4877 // Linux doesn't yet have a (official) notion of processor sets, 4878 // so just return the number of online processors. 4879 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4880 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4881 return online_cpus; 4882 } 4883 4884 void os::set_native_thread_name(const char *name) { 4885 if (Linux::_pthread_setname_np) { 4886 char buf [16]; // according to glibc manpage, 16 chars incl. '/0' 4887 snprintf(buf, sizeof(buf), "%s", name); 4888 buf[sizeof(buf) - 1] = '\0'; 4889 const int rc = Linux::_pthread_setname_np(pthread_self(), buf); 4890 // ERANGE should not happen; all other errors should just be ignored. 4891 assert(rc != ERANGE, "pthread_setname_np failed"); 4892 } 4893 } 4894 4895 bool os::distribute_processes(uint length, uint* distribution) { 4896 // Not yet implemented. 4897 return false; 4898 } 4899 4900 bool os::bind_to_processor(uint processor_id) { 4901 // Not yet implemented. 4902 return false; 4903 } 4904 4905 /// 4906 4907 void os::SuspendedThreadTask::internal_do_task() { 4908 if (do_suspend(_thread->osthread())) { 4909 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4910 do_task(context); 4911 do_resume(_thread->osthread()); 4912 } 4913 } 4914 4915 class PcFetcher : public os::SuspendedThreadTask { 4916 public: 4917 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4918 ExtendedPC result(); 4919 protected: 4920 void do_task(const os::SuspendedThreadTaskContext& context); 4921 private: 4922 ExtendedPC _epc; 4923 }; 4924 4925 ExtendedPC PcFetcher::result() { 4926 guarantee(is_done(), "task is not done yet."); 4927 return _epc; 4928 } 4929 4930 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 4931 Thread* thread = context.thread(); 4932 OSThread* osthread = thread->osthread(); 4933 if (osthread->ucontext() != NULL) { 4934 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 4935 } else { 4936 // NULL context is unexpected, double-check this is the VMThread 4937 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4938 } 4939 } 4940 4941 // Suspends the target using the signal mechanism and then grabs the PC before 4942 // resuming the target. Used by the flat-profiler only 4943 ExtendedPC os::get_thread_pc(Thread* thread) { 4944 // Make sure that it is called by the watcher for the VMThread 4945 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4946 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4947 4948 PcFetcher fetcher(thread); 4949 fetcher.run(); 4950 return fetcher.result(); 4951 } 4952 4953 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, 4954 pthread_mutex_t *_mutex, 4955 const struct timespec *_abstime) { 4956 if (is_NPTL()) { 4957 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4958 } else { 4959 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4960 // word back to default 64bit precision if condvar is signaled. Java 4961 // wants 53bit precision. Save and restore current value. 4962 int fpu = get_fpu_control_word(); 4963 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4964 set_fpu_control_word(fpu); 4965 return status; 4966 } 4967 } 4968 4969 //////////////////////////////////////////////////////////////////////////////// 4970 // debug support 4971 4972 bool os::find(address addr, outputStream* st) { 4973 Dl_info dlinfo; 4974 memset(&dlinfo, 0, sizeof(dlinfo)); 4975 if (dladdr(addr, &dlinfo) != 0) { 4976 st->print(PTR_FORMAT ": ", addr); 4977 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 4978 st->print("%s+%#x", dlinfo.dli_sname, 4979 addr - (intptr_t)dlinfo.dli_saddr); 4980 } else if (dlinfo.dli_fbase != NULL) { 4981 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4982 } else { 4983 st->print("<absolute address>"); 4984 } 4985 if (dlinfo.dli_fname != NULL) { 4986 st->print(" in %s", dlinfo.dli_fname); 4987 } 4988 if (dlinfo.dli_fbase != NULL) { 4989 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4990 } 4991 st->cr(); 4992 4993 if (Verbose) { 4994 // decode some bytes around the PC 4995 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 4996 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 4997 address lowest = (address) dlinfo.dli_sname; 4998 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4999 if (begin < lowest) begin = lowest; 5000 Dl_info dlinfo2; 5001 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 5002 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) { 5003 end = (address) dlinfo2.dli_saddr; 5004 } 5005 Disassembler::decode(begin, end, st); 5006 } 5007 return true; 5008 } 5009 return false; 5010 } 5011 5012 //////////////////////////////////////////////////////////////////////////////// 5013 // misc 5014 5015 // This does not do anything on Linux. This is basically a hook for being 5016 // able to use structured exception handling (thread-local exception filters) 5017 // on, e.g., Win32. 5018 void 5019 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 5020 JavaCallArguments* args, Thread* thread) { 5021 f(value, method, args, thread); 5022 } 5023 5024 void os::print_statistics() { 5025 } 5026 5027 int os::message_box(const char* title, const char* message) { 5028 int i; 5029 fdStream err(defaultStream::error_fd()); 5030 for (i = 0; i < 78; i++) err.print_raw("="); 5031 err.cr(); 5032 err.print_raw_cr(title); 5033 for (i = 0; i < 78; i++) err.print_raw("-"); 5034 err.cr(); 5035 err.print_raw_cr(message); 5036 for (i = 0; i < 78; i++) err.print_raw("="); 5037 err.cr(); 5038 5039 char buf[16]; 5040 // Prevent process from exiting upon "read error" without consuming all CPU 5041 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 5042 5043 return buf[0] == 'y' || buf[0] == 'Y'; 5044 } 5045 5046 int os::stat(const char *path, struct stat *sbuf) { 5047 char pathbuf[MAX_PATH]; 5048 if (strlen(path) > MAX_PATH - 1) { 5049 errno = ENAMETOOLONG; 5050 return -1; 5051 } 5052 os::native_path(strcpy(pathbuf, path)); 5053 return ::stat(pathbuf, sbuf); 5054 } 5055 5056 bool os::check_heap(bool force) { 5057 return true; 5058 } 5059 5060 // Is a (classpath) directory empty? 5061 bool os::dir_is_empty(const char* path) { 5062 DIR *dir = NULL; 5063 struct dirent *ptr; 5064 5065 dir = opendir(path); 5066 if (dir == NULL) return true; 5067 5068 // Scan the directory 5069 bool result = true; 5070 char buf[sizeof(struct dirent) + MAX_PATH]; 5071 while (result && (ptr = ::readdir(dir)) != NULL) { 5072 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5073 result = false; 5074 } 5075 } 5076 closedir(dir); 5077 return result; 5078 } 5079 5080 // This code originates from JDK's sysOpen and open64_w 5081 // from src/solaris/hpi/src/system_md.c 5082 5083 int os::open(const char *path, int oflag, int mode) { 5084 if (strlen(path) > MAX_PATH - 1) { 5085 errno = ENAMETOOLONG; 5086 return -1; 5087 } 5088 5089 // All file descriptors that are opened in the Java process and not 5090 // specifically destined for a subprocess should have the close-on-exec 5091 // flag set. If we don't set it, then careless 3rd party native code 5092 // might fork and exec without closing all appropriate file descriptors 5093 // (e.g. as we do in closeDescriptors in UNIXProcess.c), and this in 5094 // turn might: 5095 // 5096 // - cause end-of-file to fail to be detected on some file 5097 // descriptors, resulting in mysterious hangs, or 5098 // 5099 // - might cause an fopen in the subprocess to fail on a system 5100 // suffering from bug 1085341. 5101 // 5102 // (Yes, the default setting of the close-on-exec flag is a Unix 5103 // design flaw) 5104 // 5105 // See: 5106 // 1085341: 32-bit stdio routines should support file descriptors >255 5107 // 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5108 // 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5109 // 5110 // Modern Linux kernels (after 2.6.23 2007) support O_CLOEXEC with open(). 5111 // O_CLOEXEC is preferable to using FD_CLOEXEC on an open file descriptor 5112 // because it saves a system call and removes a small window where the flag 5113 // is unset. On ancient Linux kernels the O_CLOEXEC flag will be ignored 5114 // and we fall back to using FD_CLOEXEC (see below). 5115 #ifdef O_CLOEXEC 5116 oflag |= O_CLOEXEC; 5117 #endif 5118 5119 int fd = ::open64(path, oflag, mode); 5120 if (fd == -1) return -1; 5121 5122 //If the open succeeded, the file might still be a directory 5123 { 5124 struct stat64 buf64; 5125 int ret = ::fstat64(fd, &buf64); 5126 int st_mode = buf64.st_mode; 5127 5128 if (ret != -1) { 5129 if ((st_mode & S_IFMT) == S_IFDIR) { 5130 errno = EISDIR; 5131 ::close(fd); 5132 return -1; 5133 } 5134 } else { 5135 ::close(fd); 5136 return -1; 5137 } 5138 } 5139 5140 #ifdef FD_CLOEXEC 5141 // Validate that the use of the O_CLOEXEC flag on open above worked. 5142 // With recent kernels, we will perform this check exactly once. 5143 static sig_atomic_t O_CLOEXEC_is_known_to_work = 0; 5144 if (!O_CLOEXEC_is_known_to_work) { 5145 int flags = ::fcntl(fd, F_GETFD); 5146 if (flags != -1) { 5147 if ((flags & FD_CLOEXEC) != 0) 5148 O_CLOEXEC_is_known_to_work = 1; 5149 else 5150 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5151 } 5152 } 5153 #endif 5154 5155 return fd; 5156 } 5157 5158 5159 // create binary file, rewriting existing file if required 5160 int os::create_binary_file(const char* path, bool rewrite_existing) { 5161 int oflags = O_WRONLY | O_CREAT; 5162 if (!rewrite_existing) { 5163 oflags |= O_EXCL; 5164 } 5165 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5166 } 5167 5168 // return current position of file pointer 5169 jlong os::current_file_offset(int fd) { 5170 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5171 } 5172 5173 // move file pointer to the specified offset 5174 jlong os::seek_to_file_offset(int fd, jlong offset) { 5175 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5176 } 5177 5178 // This code originates from JDK's sysAvailable 5179 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5180 5181 int os::available(int fd, jlong *bytes) { 5182 jlong cur, end; 5183 int mode; 5184 struct stat64 buf64; 5185 5186 if (::fstat64(fd, &buf64) >= 0) { 5187 mode = buf64.st_mode; 5188 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5189 // XXX: is the following call interruptible? If so, this might 5190 // need to go through the INTERRUPT_IO() wrapper as for other 5191 // blocking, interruptible calls in this file. 5192 int n; 5193 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5194 *bytes = n; 5195 return 1; 5196 } 5197 } 5198 } 5199 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5200 return 0; 5201 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5202 return 0; 5203 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5204 return 0; 5205 } 5206 *bytes = end - cur; 5207 return 1; 5208 } 5209 5210 // Map a block of memory. 5211 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5212 char *addr, size_t bytes, bool read_only, 5213 bool allow_exec) { 5214 int prot; 5215 int flags = MAP_PRIVATE; 5216 5217 if (read_only) { 5218 prot = PROT_READ; 5219 } else { 5220 prot = PROT_READ | PROT_WRITE; 5221 } 5222 5223 if (allow_exec) { 5224 prot |= PROT_EXEC; 5225 } 5226 5227 if (addr != NULL) { 5228 flags |= MAP_FIXED; 5229 } 5230 5231 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5232 fd, file_offset); 5233 if (mapped_address == MAP_FAILED) { 5234 return NULL; 5235 } 5236 return mapped_address; 5237 } 5238 5239 5240 // Remap a block of memory. 5241 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5242 char *addr, size_t bytes, bool read_only, 5243 bool allow_exec) { 5244 // same as map_memory() on this OS 5245 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5246 allow_exec); 5247 } 5248 5249 5250 // Unmap a block of memory. 5251 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5252 return munmap(addr, bytes) == 0; 5253 } 5254 5255 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5256 5257 static clockid_t thread_cpu_clockid(Thread* thread) { 5258 pthread_t tid = thread->osthread()->pthread_id(); 5259 clockid_t clockid; 5260 5261 // Get thread clockid 5262 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5263 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5264 return clockid; 5265 } 5266 5267 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5268 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5269 // of a thread. 5270 // 5271 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5272 // the fast estimate available on the platform. 5273 5274 jlong os::current_thread_cpu_time() { 5275 if (os::Linux::supports_fast_thread_cpu_time()) { 5276 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5277 } else { 5278 // return user + sys since the cost is the same 5279 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5280 } 5281 } 5282 5283 jlong os::thread_cpu_time(Thread* thread) { 5284 // consistent with what current_thread_cpu_time() returns 5285 if (os::Linux::supports_fast_thread_cpu_time()) { 5286 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5287 } else { 5288 return slow_thread_cpu_time(thread, true /* user + sys */); 5289 } 5290 } 5291 5292 jlong os::current_thread_cpu_time(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(CLOCK_THREAD_CPUTIME_ID); 5295 } else { 5296 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5297 } 5298 } 5299 5300 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5301 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5302 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5303 } else { 5304 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5305 } 5306 } 5307 5308 // -1 on error. 5309 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5310 pid_t tid = thread->osthread()->thread_id(); 5311 char *s; 5312 char stat[2048]; 5313 int statlen; 5314 char proc_name[64]; 5315 int count; 5316 long sys_time, user_time; 5317 char cdummy; 5318 int idummy; 5319 long ldummy; 5320 FILE *fp; 5321 5322 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid); 5323 fp = fopen(proc_name, "r"); 5324 if (fp == NULL) return -1; 5325 statlen = fread(stat, 1, 2047, fp); 5326 stat[statlen] = '\0'; 5327 fclose(fp); 5328 5329 // Skip pid and the command string. Note that we could be dealing with 5330 // weird command names, e.g. user could decide to rename java launcher 5331 // to "java 1.4.2 :)", then the stat file would look like 5332 // 1234 (java 1.4.2 :)) R ... ... 5333 // We don't really need to know the command string, just find the last 5334 // occurrence of ")" and then start parsing from there. See bug 4726580. 5335 s = strrchr(stat, ')'); 5336 if (s == NULL) return -1; 5337 5338 // Skip blank chars 5339 do { s++; } while (s && isspace(*s)); 5340 5341 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5342 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5343 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5344 &user_time, &sys_time); 5345 if (count != 13) return -1; 5346 if (user_sys_cpu_time) { 5347 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5348 } else { 5349 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5350 } 5351 } 5352 5353 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5354 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5355 info_ptr->may_skip_backward = false; // elapsed time not wall time 5356 info_ptr->may_skip_forward = false; // elapsed time not wall time 5357 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5358 } 5359 5360 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5361 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5362 info_ptr->may_skip_backward = false; // elapsed time not wall time 5363 info_ptr->may_skip_forward = false; // elapsed time not wall time 5364 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5365 } 5366 5367 bool os::is_thread_cpu_time_supported() { 5368 return true; 5369 } 5370 5371 // System loadavg support. Returns -1 if load average cannot be obtained. 5372 // Linux doesn't yet have a (official) notion of processor sets, 5373 // so just return the system wide load average. 5374 int os::loadavg(double loadavg[], int nelem) { 5375 return ::getloadavg(loadavg, nelem); 5376 } 5377 5378 void os::pause() { 5379 char filename[MAX_PATH]; 5380 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5381 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5382 } else { 5383 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5384 } 5385 5386 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5387 if (fd != -1) { 5388 struct stat buf; 5389 ::close(fd); 5390 while (::stat(filename, &buf) == 0) { 5391 (void)::poll(NULL, 0, 100); 5392 } 5393 } else { 5394 jio_fprintf(stderr, 5395 "Could not open pause file '%s', continuing immediately.\n", filename); 5396 } 5397 } 5398 5399 5400 // Refer to the comments in os_solaris.cpp park-unpark. The next two 5401 // comment paragraphs are worth repeating here: 5402 // 5403 // Assumption: 5404 // Only one parker can exist on an event, which is why we allocate 5405 // them per-thread. Multiple unparkers can coexist. 5406 // 5407 // _Event serves as a restricted-range semaphore. 5408 // -1 : thread is blocked, i.e. there is a waiter 5409 // 0 : neutral: thread is running or ready, 5410 // could have been signaled after a wait started 5411 // 1 : signaled - thread is running or ready 5412 // 5413 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5414 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5415 // For specifics regarding the bug see GLIBC BUGID 261237 : 5416 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5417 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5418 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5419 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5420 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5421 // and monitorenter when we're using 1-0 locking. All those operations may result in 5422 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5423 // of libpthread avoids the problem, but isn't practical. 5424 // 5425 // Possible remedies: 5426 // 5427 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5428 // This is palliative and probabilistic, however. If the thread is preempted 5429 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5430 // than the minimum period may have passed, and the abstime may be stale (in the 5431 // past) resultin in a hang. Using this technique reduces the odds of a hang 5432 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5433 // 5434 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5435 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5436 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5437 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5438 // thread. 5439 // 5440 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5441 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5442 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5443 // This also works well. In fact it avoids kernel-level scalability impediments 5444 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5445 // timers in a graceful fashion. 5446 // 5447 // 4. When the abstime value is in the past it appears that control returns 5448 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5449 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5450 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5451 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5452 // It may be possible to avoid reinitialization by checking the return 5453 // value from pthread_cond_timedwait(). In addition to reinitializing the 5454 // condvar we must establish the invariant that cond_signal() is only called 5455 // within critical sections protected by the adjunct mutex. This prevents 5456 // cond_signal() from "seeing" a condvar that's in the midst of being 5457 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5458 // desirable signal-after-unlock optimization that avoids futile context switching. 5459 // 5460 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5461 // structure when a condvar is used or initialized. cond_destroy() would 5462 // release the helper structure. Our reinitialize-after-timedwait fix 5463 // put excessive stress on malloc/free and locks protecting the c-heap. 5464 // 5465 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5466 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5467 // and only enabling the work-around for vulnerable environments. 5468 5469 // utility to compute the abstime argument to timedwait: 5470 // millis is the relative timeout time 5471 // abstime will be the absolute timeout time 5472 // TODO: replace compute_abstime() with unpackTime() 5473 5474 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5475 if (millis < 0) millis = 0; 5476 5477 jlong seconds = millis / 1000; 5478 millis %= 1000; 5479 if (seconds > 50000000) { // see man cond_timedwait(3T) 5480 seconds = 50000000; 5481 } 5482 5483 if (os::supports_monotonic_clock()) { 5484 struct timespec now; 5485 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5486 assert_status(status == 0, status, "clock_gettime"); 5487 abstime->tv_sec = now.tv_sec + seconds; 5488 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5489 if (nanos >= NANOSECS_PER_SEC) { 5490 abstime->tv_sec += 1; 5491 nanos -= NANOSECS_PER_SEC; 5492 } 5493 abstime->tv_nsec = nanos; 5494 } else { 5495 struct timeval now; 5496 int status = gettimeofday(&now, NULL); 5497 assert(status == 0, "gettimeofday"); 5498 abstime->tv_sec = now.tv_sec + seconds; 5499 long usec = now.tv_usec + millis * 1000; 5500 if (usec >= 1000000) { 5501 abstime->tv_sec += 1; 5502 usec -= 1000000; 5503 } 5504 abstime->tv_nsec = usec * 1000; 5505 } 5506 return abstime; 5507 } 5508 5509 void os::PlatformEvent::park() { // AKA "down()" 5510 // Transitions for _Event: 5511 // -1 => -1 : illegal 5512 // 1 => 0 : pass - return immediately 5513 // 0 => -1 : block; then set _Event to 0 before returning 5514 5515 // Invariant: Only the thread associated with the Event/PlatformEvent 5516 // may call park(). 5517 // TODO: assert that _Assoc != NULL or _Assoc == Self 5518 assert(_nParked == 0, "invariant"); 5519 5520 int v; 5521 for (;;) { 5522 v = _Event; 5523 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5524 } 5525 guarantee(v >= 0, "invariant"); 5526 if (v == 0) { 5527 // Do this the hard way by blocking ... 5528 int status = pthread_mutex_lock(_mutex); 5529 assert_status(status == 0, status, "mutex_lock"); 5530 guarantee(_nParked == 0, "invariant"); 5531 ++_nParked; 5532 while (_Event < 0) { 5533 status = pthread_cond_wait(_cond, _mutex); 5534 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5535 // Treat this the same as if the wait was interrupted 5536 if (status == ETIME) { status = EINTR; } 5537 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5538 } 5539 --_nParked; 5540 5541 _Event = 0; 5542 status = pthread_mutex_unlock(_mutex); 5543 assert_status(status == 0, status, "mutex_unlock"); 5544 // Paranoia to ensure our locked and lock-free paths interact 5545 // correctly with each other. 5546 OrderAccess::fence(); 5547 } 5548 guarantee(_Event >= 0, "invariant"); 5549 } 5550 5551 int os::PlatformEvent::park(jlong millis) { 5552 // Transitions for _Event: 5553 // -1 => -1 : illegal 5554 // 1 => 0 : pass - return immediately 5555 // 0 => -1 : block; then set _Event to 0 before returning 5556 5557 guarantee(_nParked == 0, "invariant"); 5558 5559 int v; 5560 for (;;) { 5561 v = _Event; 5562 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5563 } 5564 guarantee(v >= 0, "invariant"); 5565 if (v != 0) return OS_OK; 5566 5567 // We do this the hard way, by blocking the thread. 5568 // Consider enforcing a minimum timeout value. 5569 struct timespec abst; 5570 compute_abstime(&abst, millis); 5571 5572 int ret = OS_TIMEOUT; 5573 int status = pthread_mutex_lock(_mutex); 5574 assert_status(status == 0, status, "mutex_lock"); 5575 guarantee(_nParked == 0, "invariant"); 5576 ++_nParked; 5577 5578 // Object.wait(timo) will return because of 5579 // (a) notification 5580 // (b) timeout 5581 // (c) thread.interrupt 5582 // 5583 // Thread.interrupt and object.notify{All} both call Event::set. 5584 // That is, we treat thread.interrupt as a special case of notification. 5585 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false. 5586 // We assume all ETIME returns are valid. 5587 // 5588 // TODO: properly differentiate simultaneous notify+interrupt. 5589 // In that case, we should propagate the notify to another waiter. 5590 5591 while (_Event < 0) { 5592 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5593 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5594 pthread_cond_destroy(_cond); 5595 pthread_cond_init(_cond, os::Linux::condAttr()); 5596 } 5597 assert_status(status == 0 || status == EINTR || 5598 status == ETIME || status == ETIMEDOUT, 5599 status, "cond_timedwait"); 5600 if (!FilterSpuriousWakeups) break; // previous semantics 5601 if (status == ETIME || status == ETIMEDOUT) break; 5602 // We consume and ignore EINTR and spurious wakeups. 5603 } 5604 --_nParked; 5605 if (_Event >= 0) { 5606 ret = OS_OK; 5607 } 5608 _Event = 0; 5609 status = pthread_mutex_unlock(_mutex); 5610 assert_status(status == 0, status, "mutex_unlock"); 5611 assert(_nParked == 0, "invariant"); 5612 // Paranoia to ensure our locked and lock-free paths interact 5613 // correctly with each other. 5614 OrderAccess::fence(); 5615 return ret; 5616 } 5617 5618 void os::PlatformEvent::unpark() { 5619 // Transitions for _Event: 5620 // 0 => 1 : just return 5621 // 1 => 1 : just return 5622 // -1 => either 0 or 1; must signal target thread 5623 // That is, we can safely transition _Event from -1 to either 5624 // 0 or 1. 5625 // See also: "Semaphores in Plan 9" by Mullender & Cox 5626 // 5627 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5628 // that it will take two back-to-back park() calls for the owning 5629 // thread to block. This has the benefit of forcing a spurious return 5630 // from the first park() call after an unpark() call which will help 5631 // shake out uses of park() and unpark() without condition variables. 5632 5633 if (Atomic::xchg(1, &_Event) >= 0) return; 5634 5635 // Wait for the thread associated with the event to vacate 5636 int status = pthread_mutex_lock(_mutex); 5637 assert_status(status == 0, status, "mutex_lock"); 5638 int AnyWaiters = _nParked; 5639 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5640 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5641 AnyWaiters = 0; 5642 pthread_cond_signal(_cond); 5643 } 5644 status = pthread_mutex_unlock(_mutex); 5645 assert_status(status == 0, status, "mutex_unlock"); 5646 if (AnyWaiters != 0) { 5647 // Note that we signal() *after* dropping the lock for "immortal" Events. 5648 // This is safe and avoids a common class of futile wakeups. In rare 5649 // circumstances this can cause a thread to return prematurely from 5650 // cond_{timed}wait() but the spurious wakeup is benign and the victim 5651 // will simply re-test the condition and re-park itself. 5652 // This provides particular benefit if the underlying platform does not 5653 // provide wait morphing. 5654 status = pthread_cond_signal(_cond); 5655 assert_status(status == 0, status, "cond_signal"); 5656 } 5657 } 5658 5659 5660 // JSR166 5661 // ------------------------------------------------------- 5662 5663 // The solaris and linux implementations of park/unpark are fairly 5664 // conservative for now, but can be improved. They currently use a 5665 // mutex/condvar pair, plus a a count. 5666 // Park decrements count if > 0, else does a condvar wait. Unpark 5667 // sets count to 1 and signals condvar. Only one thread ever waits 5668 // on the condvar. Contention seen when trying to park implies that someone 5669 // is unparking you, so don't wait. And spurious returns are fine, so there 5670 // is no need to track notifications. 5671 5672 // This code is common to linux and solaris and will be moved to a 5673 // common place in dolphin. 5674 // 5675 // The passed in time value is either a relative time in nanoseconds 5676 // or an absolute time in milliseconds. Either way it has to be unpacked 5677 // into suitable seconds and nanoseconds components and stored in the 5678 // given timespec structure. 5679 // Given time is a 64-bit value and the time_t used in the timespec is only 5680 // a signed-32-bit value (except on 64-bit Linux) we have to watch for 5681 // overflow if times way in the future are given. Further on Solaris versions 5682 // prior to 10 there is a restriction (see cond_timedwait) that the specified 5683 // number of seconds, in abstime, is less than current_time + 100,000,000. 5684 // As it will be 28 years before "now + 100000000" will overflow we can 5685 // ignore overflow and just impose a hard-limit on seconds using the value 5686 // of "now + 100,000,000". This places a limit on the timeout of about 3.17 5687 // years from "now". 5688 5689 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5690 assert(time > 0, "convertTime"); 5691 time_t max_secs = 0; 5692 5693 if (!os::supports_monotonic_clock() || isAbsolute) { 5694 struct timeval now; 5695 int status = gettimeofday(&now, NULL); 5696 assert(status == 0, "gettimeofday"); 5697 5698 max_secs = now.tv_sec + MAX_SECS; 5699 5700 if (isAbsolute) { 5701 jlong secs = time / 1000; 5702 if (secs > max_secs) { 5703 absTime->tv_sec = max_secs; 5704 } else { 5705 absTime->tv_sec = secs; 5706 } 5707 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5708 } else { 5709 jlong secs = time / NANOSECS_PER_SEC; 5710 if (secs >= MAX_SECS) { 5711 absTime->tv_sec = max_secs; 5712 absTime->tv_nsec = 0; 5713 } else { 5714 absTime->tv_sec = now.tv_sec + secs; 5715 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5716 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5717 absTime->tv_nsec -= NANOSECS_PER_SEC; 5718 ++absTime->tv_sec; // note: this must be <= max_secs 5719 } 5720 } 5721 } 5722 } else { 5723 // must be relative using monotonic clock 5724 struct timespec now; 5725 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5726 assert_status(status == 0, status, "clock_gettime"); 5727 max_secs = now.tv_sec + MAX_SECS; 5728 jlong secs = time / NANOSECS_PER_SEC; 5729 if (secs >= MAX_SECS) { 5730 absTime->tv_sec = max_secs; 5731 absTime->tv_nsec = 0; 5732 } else { 5733 absTime->tv_sec = now.tv_sec + secs; 5734 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5735 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5736 absTime->tv_nsec -= NANOSECS_PER_SEC; 5737 ++absTime->tv_sec; // note: this must be <= max_secs 5738 } 5739 } 5740 } 5741 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5742 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5743 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5744 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5745 } 5746 5747 void Parker::park(bool isAbsolute, jlong time) { 5748 // Ideally we'd do something useful while spinning, such 5749 // as calling unpackTime(). 5750 5751 // Optional fast-path check: 5752 // Return immediately if a permit is available. 5753 // We depend on Atomic::xchg() having full barrier semantics 5754 // since we are doing a lock-free update to _counter. 5755 if (Atomic::xchg(0, &_counter) > 0) return; 5756 5757 Thread* thread = Thread::current(); 5758 assert(thread->is_Java_thread(), "Must be JavaThread"); 5759 JavaThread *jt = (JavaThread *)thread; 5760 5761 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5762 // Check interrupt before trying to wait 5763 if (Thread::is_interrupted(thread, false)) { 5764 return; 5765 } 5766 5767 // Next, demultiplex/decode time arguments 5768 timespec absTime; 5769 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all 5770 return; 5771 } 5772 if (time > 0) { 5773 unpackTime(&absTime, isAbsolute, time); 5774 } 5775 5776 5777 // Enter safepoint region 5778 // Beware of deadlocks such as 6317397. 5779 // The per-thread Parker:: mutex is a classic leaf-lock. 5780 // In particular a thread must never block on the Threads_lock while 5781 // holding the Parker:: mutex. If safepoints are pending both the 5782 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5783 ThreadBlockInVM tbivm(jt); 5784 5785 // Don't wait if cannot get lock since interference arises from 5786 // unblocking. Also. check interrupt before trying wait 5787 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5788 return; 5789 } 5790 5791 int status; 5792 if (_counter > 0) { // no wait needed 5793 _counter = 0; 5794 status = pthread_mutex_unlock(_mutex); 5795 assert(status == 0, "invariant"); 5796 // Paranoia to ensure our locked and lock-free paths interact 5797 // correctly with each other and Java-level accesses. 5798 OrderAccess::fence(); 5799 return; 5800 } 5801 5802 #ifdef ASSERT 5803 // Don't catch signals while blocked; let the running threads have the signals. 5804 // (This allows a debugger to break into the running thread.) 5805 sigset_t oldsigs; 5806 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5807 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5808 #endif 5809 5810 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5811 jt->set_suspend_equivalent(); 5812 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5813 5814 assert(_cur_index == -1, "invariant"); 5815 if (time == 0) { 5816 _cur_index = REL_INDEX; // arbitrary choice when not timed 5817 status = pthread_cond_wait(&_cond[_cur_index], _mutex); 5818 } else { 5819 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5820 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime); 5821 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5822 pthread_cond_destroy(&_cond[_cur_index]); 5823 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5824 } 5825 } 5826 _cur_index = -1; 5827 assert_status(status == 0 || status == EINTR || 5828 status == ETIME || status == ETIMEDOUT, 5829 status, "cond_timedwait"); 5830 5831 #ifdef ASSERT 5832 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5833 #endif 5834 5835 _counter = 0; 5836 status = pthread_mutex_unlock(_mutex); 5837 assert_status(status == 0, status, "invariant"); 5838 // Paranoia to ensure our locked and lock-free paths interact 5839 // correctly with each other and Java-level accesses. 5840 OrderAccess::fence(); 5841 5842 // If externally suspended while waiting, re-suspend 5843 if (jt->handle_special_suspend_equivalent_condition()) { 5844 jt->java_suspend_self(); 5845 } 5846 } 5847 5848 void Parker::unpark() { 5849 int status = pthread_mutex_lock(_mutex); 5850 assert(status == 0, "invariant"); 5851 const int s = _counter; 5852 _counter = 1; 5853 if (s < 1) { 5854 // thread might be parked 5855 if (_cur_index != -1) { 5856 // thread is definitely parked 5857 if (WorkAroundNPTLTimedWaitHang) { 5858 status = pthread_cond_signal(&_cond[_cur_index]); 5859 assert(status == 0, "invariant"); 5860 status = pthread_mutex_unlock(_mutex); 5861 assert(status == 0, "invariant"); 5862 } else { 5863 status = pthread_mutex_unlock(_mutex); 5864 assert(status == 0, "invariant"); 5865 status = pthread_cond_signal(&_cond[_cur_index]); 5866 assert(status == 0, "invariant"); 5867 } 5868 } else { 5869 pthread_mutex_unlock(_mutex); 5870 assert(status == 0, "invariant"); 5871 } 5872 } else { 5873 pthread_mutex_unlock(_mutex); 5874 assert(status == 0, "invariant"); 5875 } 5876 } 5877 5878 5879 extern char** environ; 5880 5881 #ifndef __NR_fork 5882 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) AARCH64_ONLY(1079) 5883 #endif 5884 5885 #ifndef __NR_execve 5886 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) AARCH64_ONLY(221) 5887 #endif 5888 5889 // Run the specified command in a separate process. Return its exit value, 5890 // or -1 on failure (e.g. can't fork a new process). 5891 // Unlike system(), this function can be called from signal handler. It 5892 // doesn't block SIGINT et al. 5893 int os::fork_and_exec(char* cmd) { 5894 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5895 5896 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 5897 // pthread_atfork handlers and reset pthread library. All we need is a 5898 // separate process to execve. Make a direct syscall to fork process. 5899 // On IA64 there's no fork syscall, we have to use fork() and hope for 5900 // the best... 5901 pid_t pid = NOT_IA64(syscall(__NR_fork);) 5902 IA64_ONLY(fork();) 5903 5904 if (pid < 0) { 5905 // fork failed 5906 return -1; 5907 5908 } else if (pid == 0) { 5909 // child process 5910 5911 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 5912 // first to kill every thread on the thread list. Because this list is 5913 // not reset by fork() (see notes above), execve() will instead kill 5914 // every thread in the parent process. We know this is the only thread 5915 // in the new process, so make a system call directly. 5916 // IA64 should use normal execve() from glibc to match the glibc fork() 5917 // above. 5918 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 5919 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 5920 5921 // execve failed 5922 _exit(-1); 5923 5924 } else { 5925 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5926 // care about the actual exit code, for now. 5927 5928 int status; 5929 5930 // Wait for the child process to exit. This returns immediately if 5931 // the child has already exited. */ 5932 while (waitpid(pid, &status, 0) < 0) { 5933 switch (errno) { 5934 case ECHILD: return 0; 5935 case EINTR: break; 5936 default: return -1; 5937 } 5938 } 5939 5940 if (WIFEXITED(status)) { 5941 // The child exited normally; get its exit code. 5942 return WEXITSTATUS(status); 5943 } else if (WIFSIGNALED(status)) { 5944 // The child exited because of a signal 5945 // The best value to return is 0x80 + signal number, 5946 // because that is what all Unix shells do, and because 5947 // it allows callers to distinguish between process exit and 5948 // process death by signal. 5949 return 0x80 + WTERMSIG(status); 5950 } else { 5951 // Unknown exit code; pass it through 5952 return status; 5953 } 5954 } 5955 } 5956 5957 // is_headless_jre() 5958 // 5959 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 5960 // in order to report if we are running in a headless jre 5961 // 5962 // Since JDK8 xawt/libmawt.so was moved into the same directory 5963 // as libawt.so, and renamed libawt_xawt.so 5964 // 5965 bool os::is_headless_jre() { 5966 struct stat statbuf; 5967 char buf[MAXPATHLEN]; 5968 char libmawtpath[MAXPATHLEN]; 5969 const char *xawtstr = "/xawt/libmawt.so"; 5970 const char *new_xawtstr = "/libawt_xawt.so"; 5971 char *p; 5972 5973 // Get path to libjvm.so 5974 os::jvm_path(buf, sizeof(buf)); 5975 5976 // Get rid of libjvm.so 5977 p = strrchr(buf, '/'); 5978 if (p == NULL) { 5979 return false; 5980 } else { 5981 *p = '\0'; 5982 } 5983 5984 // Get rid of client or server 5985 p = strrchr(buf, '/'); 5986 if (p == NULL) { 5987 return false; 5988 } else { 5989 *p = '\0'; 5990 } 5991 5992 // check xawt/libmawt.so 5993 strcpy(libmawtpath, buf); 5994 strcat(libmawtpath, xawtstr); 5995 if (::stat(libmawtpath, &statbuf) == 0) return false; 5996 5997 // check libawt_xawt.so 5998 strcpy(libmawtpath, buf); 5999 strcat(libmawtpath, new_xawtstr); 6000 if (::stat(libmawtpath, &statbuf) == 0) return false; 6001 6002 return true; 6003 } 6004 6005 // Get the default path to the core file 6006 // Returns the length of the string 6007 int os::get_core_path(char* buffer, size_t bufferSize) { 6008 /* 6009 * Max length of /proc/sys/kernel/core_pattern is 128 characters. 6010 * See https://www.kernel.org/doc/Documentation/sysctl/kernel.txt 6011 */ 6012 const int core_pattern_len = 129; 6013 char core_pattern[core_pattern_len] = {0}; 6014 6015 int core_pattern_file = ::open("/proc/sys/kernel/core_pattern", O_RDONLY); 6016 if (core_pattern_file != -1) { 6017 ssize_t ret = ::read(core_pattern_file, core_pattern, core_pattern_len); 6018 ::close(core_pattern_file); 6019 6020 if (ret > 0) { 6021 char *last_char = core_pattern + strlen(core_pattern) - 1; 6022 6023 if (*last_char == '\n') { 6024 *last_char = '\0'; 6025 } 6026 } 6027 } 6028 6029 if (strlen(core_pattern) == 0) { 6030 return 0; 6031 } 6032 6033 char *pid_pos = strstr(core_pattern, "%p"); 6034 size_t written; 6035 6036 if (core_pattern[0] == '/') { 6037 written = jio_snprintf(buffer, bufferSize, core_pattern); 6038 } else { 6039 char cwd[PATH_MAX]; 6040 6041 const char* p = get_current_directory(cwd, PATH_MAX); 6042 if (p == NULL) { 6043 assert(p != NULL, "failed to get current directory"); 6044 return 0; 6045 } 6046 6047 if (core_pattern[0] == '|') { 6048 written = jio_snprintf(buffer, bufferSize, 6049 "\"%s\" (or dumping to %s/core.%d)", 6050 &core_pattern[1], p, current_process_id()); 6051 } else { 6052 written = jio_snprintf(buffer, bufferSize, "%s/%s", p, core_pattern); 6053 } 6054 } 6055 6056 if ((written >= 0) && (written < bufferSize) 6057 && (pid_pos == NULL) && (core_pattern[0] != '|')) { 6058 int core_uses_pid_file = ::open("/proc/sys/kernel/core_uses_pid", O_RDONLY); 6059 6060 if (core_uses_pid_file != -1) { 6061 char core_uses_pid = 0; 6062 ssize_t ret = ::read(core_uses_pid_file, &core_uses_pid, 1); 6063 ::close(core_uses_pid_file); 6064 6065 if (core_uses_pid == '1'){ 6066 jio_snprintf(buffer + written, bufferSize - written, 6067 ".%d", current_process_id()); 6068 } 6069 } 6070 } 6071 6072 return strlen(buffer); 6073 } 6074 6075 /////////////// Unit tests /////////////// 6076 6077 #ifndef PRODUCT 6078 6079 #define test_log(...) \ 6080 do { \ 6081 if (VerboseInternalVMTests) { \ 6082 tty->print_cr(__VA_ARGS__); \ 6083 tty->flush(); \ 6084 } \ 6085 } while (false) 6086 6087 class TestReserveMemorySpecial : AllStatic { 6088 public: 6089 static void small_page_write(void* addr, size_t size) { 6090 size_t page_size = os::vm_page_size(); 6091 6092 char* end = (char*)addr + size; 6093 for (char* p = (char*)addr; p < end; p += page_size) { 6094 *p = 1; 6095 } 6096 } 6097 6098 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6099 if (!UseHugeTLBFS) { 6100 return; 6101 } 6102 6103 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6104 6105 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6106 6107 if (addr != NULL) { 6108 small_page_write(addr, size); 6109 6110 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6111 } 6112 } 6113 6114 static void test_reserve_memory_special_huge_tlbfs_only() { 6115 if (!UseHugeTLBFS) { 6116 return; 6117 } 6118 6119 size_t lp = os::large_page_size(); 6120 6121 for (size_t size = lp; size <= lp * 10; size += lp) { 6122 test_reserve_memory_special_huge_tlbfs_only(size); 6123 } 6124 } 6125 6126 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) { 6127 if (!UseHugeTLBFS) { 6128 return; 6129 } 6130 6131 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")", 6132 size, alignment); 6133 6134 assert(size >= os::large_page_size(), "Incorrect input to test"); 6135 6136 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6137 6138 if (addr != NULL) { 6139 small_page_write(addr, size); 6140 6141 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6142 } 6143 } 6144 6145 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) { 6146 size_t lp = os::large_page_size(); 6147 size_t ag = os::vm_allocation_granularity(); 6148 6149 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6150 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment); 6151 } 6152 } 6153 6154 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6155 size_t lp = os::large_page_size(); 6156 size_t ag = os::vm_allocation_granularity(); 6157 6158 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp); 6159 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag); 6160 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2); 6161 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2); 6162 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag); 6163 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag); 6164 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2); 6165 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10); 6166 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2); 6167 } 6168 6169 static void test_reserve_memory_special_huge_tlbfs() { 6170 if (!UseHugeTLBFS) { 6171 return; 6172 } 6173 6174 test_reserve_memory_special_huge_tlbfs_only(); 6175 test_reserve_memory_special_huge_tlbfs_mixed(); 6176 } 6177 6178 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6179 if (!UseSHM) { 6180 return; 6181 } 6182 6183 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6184 6185 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6186 6187 if (addr != NULL) { 6188 assert(is_ptr_aligned(addr, alignment), "Check"); 6189 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6190 6191 small_page_write(addr, size); 6192 6193 os::Linux::release_memory_special_shm(addr, size); 6194 } 6195 } 6196 6197 static void test_reserve_memory_special_shm() { 6198 size_t lp = os::large_page_size(); 6199 size_t ag = os::vm_allocation_granularity(); 6200 6201 for (size_t size = ag; size < lp * 3; size += ag) { 6202 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6203 test_reserve_memory_special_shm(size, alignment); 6204 } 6205 } 6206 } 6207 6208 static void test() { 6209 test_reserve_memory_special_huge_tlbfs(); 6210 test_reserve_memory_special_shm(); 6211 } 6212 }; 6213 6214 void TestReserveMemorySpecial_test() { 6215 TestReserveMemorySpecial::test(); 6216 } 6217 6218 #endif