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 // Declarations 162 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time); 163 164 // utility functions 165 166 static int SR_initialize(); 167 168 julong os::available_memory() { 169 return Linux::available_memory(); 170 } 171 172 julong os::Linux::available_memory() { 173 // values in struct sysinfo are "unsigned long" 174 struct sysinfo si; 175 sysinfo(&si); 176 177 return (julong)si.freeram * si.mem_unit; 178 } 179 180 julong os::physical_memory() { 181 return Linux::physical_memory(); 182 } 183 184 // Return true if user is running as root. 185 186 bool os::have_special_privileges() { 187 static bool init = false; 188 static bool privileges = false; 189 if (!init) { 190 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 191 init = true; 192 } 193 return privileges; 194 } 195 196 197 #ifndef SYS_gettid 198 // i386: 224, ia64: 1105, amd64: 186, sparc 143 199 #ifdef __ia64__ 200 #define SYS_gettid 1105 201 #else 202 #ifdef __i386__ 203 #define SYS_gettid 224 204 #else 205 #ifdef __amd64__ 206 #define SYS_gettid 186 207 #else 208 #ifdef __sparc__ 209 #define SYS_gettid 143 210 #else 211 #error define gettid for the arch 212 #endif 213 #endif 214 #endif 215 #endif 216 #endif 217 218 // Cpu architecture string 219 static char cpu_arch[] = HOTSPOT_LIB_ARCH; 220 221 222 // pid_t gettid() 223 // 224 // Returns the kernel thread id of the currently running thread. Kernel 225 // thread id is used to access /proc. 226 // 227 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 228 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 229 // 230 pid_t os::Linux::gettid() { 231 int rslt = syscall(SYS_gettid); 232 if (rslt == -1) { 233 // old kernel, no NPTL support 234 return getpid(); 235 } else { 236 return (pid_t)rslt; 237 } 238 } 239 240 // Most versions of linux have a bug where the number of processors are 241 // determined by looking at the /proc file system. In a chroot environment, 242 // the system call returns 1. This causes the VM to act as if it is 243 // a single processor and elide locking (see is_MP() call). 244 static bool unsafe_chroot_detected = false; 245 static const char *unstable_chroot_error = "/proc file system not found.\n" 246 "Java may be unstable running multithreaded in a chroot " 247 "environment on Linux when /proc filesystem is not mounted."; 248 249 void os::Linux::initialize_system_info() { 250 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 251 if (processor_count() == 1) { 252 pid_t pid = os::Linux::gettid(); 253 char fname[32]; 254 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 255 FILE *fp = fopen(fname, "r"); 256 if (fp == NULL) { 257 unsafe_chroot_detected = true; 258 } else { 259 fclose(fp); 260 } 261 } 262 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 263 assert(processor_count() > 0, "linux error"); 264 } 265 266 void os::init_system_properties_values() { 267 // The next steps are taken in the product version: 268 // 269 // Obtain the JAVA_HOME value from the location of libjvm.so. 270 // This library should be located at: 271 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so. 272 // 273 // If "/jre/lib/" appears at the right place in the path, then we 274 // assume libjvm.so is installed in a JDK and we use this path. 275 // 276 // Otherwise exit with message: "Could not create the Java virtual machine." 277 // 278 // The following extra steps are taken in the debugging version: 279 // 280 // If "/jre/lib/" does NOT appear at the right place in the path 281 // instead of exit check for $JAVA_HOME environment variable. 282 // 283 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 284 // then we append a fake suffix "hotspot/libjvm.so" to this path so 285 // it looks like libjvm.so is installed there 286 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so. 287 // 288 // Otherwise exit. 289 // 290 // Important note: if the location of libjvm.so changes this 291 // code needs to be changed accordingly. 292 293 // See ld(1): 294 // The linker uses the following search paths to locate required 295 // shared libraries: 296 // 1: ... 297 // ... 298 // 7: The default directories, normally /lib and /usr/lib. 299 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 300 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 301 #else 302 #define DEFAULT_LIBPATH "/lib:/usr/lib" 303 #endif 304 305 // Base path of extensions installed on the system. 306 #define SYS_EXT_DIR "/usr/java/packages" 307 #define EXTENSIONS_DIR "/lib/ext" 308 309 // Buffer that fits several sprintfs. 310 // Note that the space for the colon and the trailing null are provided 311 // by the nulls included by the sizeof operator. 312 const size_t bufsize = 313 MAX2((size_t)MAXPATHLEN, // For dll_dir & friends. 314 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR)); // extensions dir 315 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 316 317 // sysclasspath, java_home, dll_dir 318 { 319 char *pslash; 320 os::jvm_path(buf, bufsize); 321 322 // Found the full path to libjvm.so. 323 // Now cut the path to <java_home>/jre if we can. 324 pslash = strrchr(buf, '/'); 325 if (pslash != NULL) { 326 *pslash = '\0'; // Get rid of /libjvm.so. 327 } 328 pslash = strrchr(buf, '/'); 329 if (pslash != NULL) { 330 *pslash = '\0'; // Get rid of /{client|server|hotspot}. 331 } 332 Arguments::set_dll_dir(buf); 333 334 if (pslash != NULL) { 335 pslash = strrchr(buf, '/'); 336 if (pslash != NULL) { 337 *pslash = '\0'; // Get rid of /<arch>. 338 pslash = strrchr(buf, '/'); 339 if (pslash != NULL) { 340 *pslash = '\0'; // Get rid of /lib. 341 } 342 } 343 } 344 Arguments::set_java_home(buf); 345 set_boot_path('/', ':'); 346 } 347 348 // Where to look for native libraries. 349 // 350 // Note: Due to a legacy implementation, most of the library path 351 // is set in the launcher. This was to accomodate linking restrictions 352 // on legacy Linux implementations (which are no longer supported). 353 // Eventually, all the library path setting will be done here. 354 // 355 // However, to prevent the proliferation of improperly built native 356 // libraries, the new path component /usr/java/packages is added here. 357 // Eventually, all the library path setting will be done here. 358 { 359 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It 360 // should always exist (until the legacy problem cited above is 361 // addressed). 362 const char *v = ::getenv("LD_LIBRARY_PATH"); 363 const char *v_colon = ":"; 364 if (v == NULL) { v = ""; v_colon = ""; } 365 // That's +1 for the colon and +1 for the trailing '\0'. 366 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char, 367 strlen(v) + 1 + 368 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1, 369 mtInternal); 370 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch); 371 Arguments::set_library_path(ld_library_path); 372 FREE_C_HEAP_ARRAY(char, ld_library_path); 373 } 374 375 // Extensions directories. 376 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home()); 377 Arguments::set_ext_dirs(buf); 378 379 FREE_C_HEAP_ARRAY(char, buf); 380 381 #undef DEFAULT_LIBPATH 382 #undef SYS_EXT_DIR 383 #undef EXTENSIONS_DIR 384 } 385 386 //////////////////////////////////////////////////////////////////////////////// 387 // breakpoint support 388 389 void os::breakpoint() { 390 BREAKPOINT; 391 } 392 393 extern "C" void breakpoint() { 394 // use debugger to set breakpoint here 395 } 396 397 //////////////////////////////////////////////////////////////////////////////// 398 // signal support 399 400 debug_only(static bool signal_sets_initialized = false); 401 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 402 403 bool os::Linux::is_sig_ignored(int sig) { 404 struct sigaction oact; 405 sigaction(sig, (struct sigaction*)NULL, &oact); 406 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 407 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 408 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) { 409 return true; 410 } else { 411 return false; 412 } 413 } 414 415 void os::Linux::signal_sets_init() { 416 // Should also have an assertion stating we are still single-threaded. 417 assert(!signal_sets_initialized, "Already initialized"); 418 // Fill in signals that are necessarily unblocked for all threads in 419 // the VM. Currently, we unblock the following signals: 420 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 421 // by -Xrs (=ReduceSignalUsage)); 422 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 423 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 424 // the dispositions or masks wrt these signals. 425 // Programs embedding the VM that want to use the above signals for their 426 // own purposes must, at this time, use the "-Xrs" option to prevent 427 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 428 // (See bug 4345157, and other related bugs). 429 // In reality, though, unblocking these signals is really a nop, since 430 // these signals are not blocked by default. 431 sigemptyset(&unblocked_sigs); 432 sigemptyset(&allowdebug_blocked_sigs); 433 sigaddset(&unblocked_sigs, SIGILL); 434 sigaddset(&unblocked_sigs, SIGSEGV); 435 sigaddset(&unblocked_sigs, SIGBUS); 436 sigaddset(&unblocked_sigs, SIGFPE); 437 #if defined(PPC64) 438 sigaddset(&unblocked_sigs, SIGTRAP); 439 #endif 440 sigaddset(&unblocked_sigs, SR_signum); 441 442 if (!ReduceSignalUsage) { 443 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 444 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 445 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 446 } 447 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 448 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 449 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 450 } 451 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 452 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 453 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 454 } 455 } 456 // Fill in signals that are blocked by all but the VM thread. 457 sigemptyset(&vm_sigs); 458 if (!ReduceSignalUsage) { 459 sigaddset(&vm_sigs, BREAK_SIGNAL); 460 } 461 debug_only(signal_sets_initialized = true); 462 463 } 464 465 // These are signals that are unblocked while a thread is running Java. 466 // (For some reason, they get blocked by default.) 467 sigset_t* os::Linux::unblocked_signals() { 468 assert(signal_sets_initialized, "Not initialized"); 469 return &unblocked_sigs; 470 } 471 472 // These are the signals that are blocked while a (non-VM) thread is 473 // running Java. Only the VM thread handles these signals. 474 sigset_t* os::Linux::vm_signals() { 475 assert(signal_sets_initialized, "Not initialized"); 476 return &vm_sigs; 477 } 478 479 // These are signals that are blocked during cond_wait to allow debugger in 480 sigset_t* os::Linux::allowdebug_blocked_signals() { 481 assert(signal_sets_initialized, "Not initialized"); 482 return &allowdebug_blocked_sigs; 483 } 484 485 void os::Linux::hotspot_sigmask(Thread* thread) { 486 487 //Save caller's signal mask before setting VM signal mask 488 sigset_t caller_sigmask; 489 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 490 491 OSThread* osthread = thread->osthread(); 492 osthread->set_caller_sigmask(caller_sigmask); 493 494 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 495 496 if (!ReduceSignalUsage) { 497 if (thread->is_VM_thread()) { 498 // Only the VM thread handles BREAK_SIGNAL ... 499 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 500 } else { 501 // ... all other threads block BREAK_SIGNAL 502 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 503 } 504 } 505 } 506 507 ////////////////////////////////////////////////////////////////////////////// 508 // detecting pthread library 509 510 void os::Linux::libpthread_init() { 511 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 512 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 513 // generic name for earlier versions. 514 // Define macros here so we can build HotSpot on old systems. 515 #ifndef _CS_GNU_LIBC_VERSION 516 #define _CS_GNU_LIBC_VERSION 2 517 #endif 518 #ifndef _CS_GNU_LIBPTHREAD_VERSION 519 #define _CS_GNU_LIBPTHREAD_VERSION 3 520 #endif 521 522 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 523 if (n > 0) { 524 char *str = (char *)malloc(n, mtInternal); 525 confstr(_CS_GNU_LIBC_VERSION, str, n); 526 os::Linux::set_glibc_version(str); 527 } else { 528 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 529 static char _gnu_libc_version[32]; 530 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 531 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 532 os::Linux::set_glibc_version(_gnu_libc_version); 533 } 534 535 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 536 if (n > 0) { 537 char *str = (char *)malloc(n, mtInternal); 538 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 539 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 540 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 541 // is the case. LinuxThreads has a hard limit on max number of threads. 542 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 543 // On the other hand, NPTL does not have such a limit, sysconf() 544 // will return -1 and errno is not changed. Check if it is really NPTL. 545 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 546 strstr(str, "NPTL") && 547 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 548 free(str); 549 os::Linux::set_libpthread_version("linuxthreads"); 550 } else { 551 os::Linux::set_libpthread_version(str); 552 } 553 } else { 554 // glibc before 2.3.2 only has LinuxThreads. 555 os::Linux::set_libpthread_version("linuxthreads"); 556 } 557 558 if (strstr(libpthread_version(), "NPTL")) { 559 os::Linux::set_is_NPTL(); 560 } else { 561 os::Linux::set_is_LinuxThreads(); 562 } 563 564 // LinuxThreads have two flavors: floating-stack mode, which allows variable 565 // stack size; and fixed-stack mode. NPTL is always floating-stack. 566 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 567 os::Linux::set_is_floating_stack(); 568 } 569 } 570 571 ///////////////////////////////////////////////////////////////////////////// 572 // thread stack 573 574 // Force Linux kernel to expand current thread stack. If "bottom" is close 575 // to the stack guard, caller should block all signals. 576 // 577 // MAP_GROWSDOWN: 578 // A special mmap() flag that is used to implement thread stacks. It tells 579 // kernel that the memory region should extend downwards when needed. This 580 // allows early versions of LinuxThreads to only mmap the first few pages 581 // when creating a new thread. Linux kernel will automatically expand thread 582 // stack as needed (on page faults). 583 // 584 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 585 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 586 // region, it's hard to tell if the fault is due to a legitimate stack 587 // access or because of reading/writing non-exist memory (e.g. buffer 588 // overrun). As a rule, if the fault happens below current stack pointer, 589 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 590 // application (see Linux kernel fault.c). 591 // 592 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 593 // stack overflow detection. 594 // 595 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 596 // not use this flag. However, the stack of initial thread is not created 597 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 598 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 599 // and then attach the thread to JVM. 600 // 601 // To get around the problem and allow stack banging on Linux, we need to 602 // manually expand thread stack after receiving the SIGSEGV. 603 // 604 // There are two ways to expand thread stack to address "bottom", we used 605 // both of them in JVM before 1.5: 606 // 1. adjust stack pointer first so that it is below "bottom", and then 607 // touch "bottom" 608 // 2. mmap() the page in question 609 // 610 // Now alternate signal stack is gone, it's harder to use 2. For instance, 611 // if current sp is already near the lower end of page 101, and we need to 612 // call mmap() to map page 100, it is possible that part of the mmap() frame 613 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 614 // That will destroy the mmap() frame and cause VM to crash. 615 // 616 // The following code works by adjusting sp first, then accessing the "bottom" 617 // page to force a page fault. Linux kernel will then automatically expand the 618 // stack mapping. 619 // 620 // _expand_stack_to() assumes its frame size is less than page size, which 621 // should always be true if the function is not inlined. 622 623 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 624 #define NOINLINE 625 #else 626 #define NOINLINE __attribute__ ((noinline)) 627 #endif 628 629 static void _expand_stack_to(address bottom) NOINLINE; 630 631 static void _expand_stack_to(address bottom) { 632 address sp; 633 size_t size; 634 volatile char *p; 635 636 // Adjust bottom to point to the largest address within the same page, it 637 // gives us a one-page buffer if alloca() allocates slightly more memory. 638 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 639 bottom += os::Linux::page_size() - 1; 640 641 // sp might be slightly above current stack pointer; if that's the case, we 642 // will alloca() a little more space than necessary, which is OK. Don't use 643 // os::current_stack_pointer(), as its result can be slightly below current 644 // stack pointer, causing us to not alloca enough to reach "bottom". 645 sp = (address)&sp; 646 647 if (sp > bottom) { 648 size = sp - bottom; 649 p = (volatile char *)alloca(size); 650 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 651 p[0] = '\0'; 652 } 653 } 654 655 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 656 assert(t!=NULL, "just checking"); 657 assert(t->osthread()->expanding_stack(), "expand should be set"); 658 assert(t->stack_base() != NULL, "stack_base was not initialized"); 659 660 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 661 sigset_t mask_all, old_sigset; 662 sigfillset(&mask_all); 663 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 664 _expand_stack_to(addr); 665 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 666 return true; 667 } 668 return false; 669 } 670 671 ////////////////////////////////////////////////////////////////////////////// 672 // create new thread 673 674 static address highest_vm_reserved_address(); 675 676 // check if it's safe to start a new thread 677 static bool _thread_safety_check(Thread* thread) { 678 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 679 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 680 // Heap is mmap'ed at lower end of memory space. Thread stacks are 681 // allocated (MAP_FIXED) from high address space. Every thread stack 682 // occupies a fixed size slot (usually 2Mbytes, but user can change 683 // it to other values if they rebuild LinuxThreads). 684 // 685 // Problem with MAP_FIXED is that mmap() can still succeed even part of 686 // the memory region has already been mmap'ed. That means if we have too 687 // many threads and/or very large heap, eventually thread stack will 688 // collide with heap. 689 // 690 // Here we try to prevent heap/stack collision by comparing current 691 // stack bottom with the highest address that has been mmap'ed by JVM 692 // plus a safety margin for memory maps created by native code. 693 // 694 // This feature can be disabled by setting ThreadSafetyMargin to 0 695 // 696 if (ThreadSafetyMargin > 0) { 697 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 698 699 // not safe if our stack extends below the safety margin 700 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 701 } else { 702 return true; 703 } 704 } else { 705 // Floating stack LinuxThreads or NPTL: 706 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 707 // there's not enough space left, pthread_create() will fail. If we come 708 // here, that means enough space has been reserved for stack. 709 return true; 710 } 711 } 712 713 // Thread start routine for all newly created threads 714 static void *java_start(Thread *thread) { 715 // Try to randomize the cache line index of hot stack frames. 716 // This helps when threads of the same stack traces evict each other's 717 // cache lines. The threads can be either from the same JVM instance, or 718 // from different JVM instances. The benefit is especially true for 719 // processors with hyperthreading technology. 720 static int counter = 0; 721 int pid = os::current_process_id(); 722 alloca(((pid ^ counter++) & 7) * 128); 723 724 ThreadLocalStorage::set_thread(thread); 725 726 OSThread* osthread = thread->osthread(); 727 Monitor* sync = osthread->startThread_lock(); 728 729 // non floating stack LinuxThreads needs extra check, see above 730 if (!_thread_safety_check(thread)) { 731 // notify parent thread 732 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 733 osthread->set_state(ZOMBIE); 734 sync->notify_all(); 735 return NULL; 736 } 737 738 // thread_id is kernel thread id (similar to Solaris LWP id) 739 osthread->set_thread_id(os::Linux::gettid()); 740 741 if (UseNUMA) { 742 int lgrp_id = os::numa_get_group_id(); 743 if (lgrp_id != -1) { 744 thread->set_lgrp_id(lgrp_id); 745 } 746 } 747 // initialize signal mask for this thread 748 os::Linux::hotspot_sigmask(thread); 749 750 // initialize floating point control register 751 os::Linux::init_thread_fpu_state(); 752 753 // handshaking with parent thread 754 { 755 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 756 757 // notify parent thread 758 osthread->set_state(INITIALIZED); 759 sync->notify_all(); 760 761 // wait until os::start_thread() 762 while (osthread->get_state() == INITIALIZED) { 763 sync->wait(Mutex::_no_safepoint_check_flag); 764 } 765 } 766 767 // call one more level start routine 768 thread->run(); 769 770 return 0; 771 } 772 773 bool os::create_thread(Thread* thread, ThreadType thr_type, 774 size_t stack_size) { 775 assert(thread->osthread() == NULL, "caller responsible"); 776 777 // Allocate the OSThread object 778 OSThread* osthread = new OSThread(NULL, NULL); 779 if (osthread == NULL) { 780 return false; 781 } 782 783 // set the correct thread state 784 osthread->set_thread_type(thr_type); 785 786 // Initial state is ALLOCATED but not INITIALIZED 787 osthread->set_state(ALLOCATED); 788 789 thread->set_osthread(osthread); 790 791 // init thread attributes 792 pthread_attr_t attr; 793 pthread_attr_init(&attr); 794 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 795 796 // stack size 797 if (os::Linux::supports_variable_stack_size()) { 798 // calculate stack size if it's not specified by caller 799 if (stack_size == 0) { 800 stack_size = os::Linux::default_stack_size(thr_type); 801 802 switch (thr_type) { 803 case os::java_thread: 804 // Java threads use ThreadStackSize which default value can be 805 // changed with the flag -Xss 806 assert(JavaThread::stack_size_at_create() > 0, "this should be set"); 807 stack_size = JavaThread::stack_size_at_create(); 808 break; 809 case os::compiler_thread: 810 if (CompilerThreadStackSize > 0) { 811 stack_size = (size_t)(CompilerThreadStackSize * K); 812 break; 813 } // else fall through: 814 // use VMThreadStackSize if CompilerThreadStackSize is not defined 815 case os::vm_thread: 816 case os::pgc_thread: 817 case os::cgc_thread: 818 case os::watcher_thread: 819 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 820 break; 821 } 822 } 823 824 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 825 pthread_attr_setstacksize(&attr, stack_size); 826 } else { 827 // let pthread_create() pick the default value. 828 } 829 830 // glibc guard page 831 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 832 833 ThreadState state; 834 835 { 836 // Serialize thread creation if we are running with fixed stack LinuxThreads 837 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 838 if (lock) { 839 os::Linux::createThread_lock()->lock_without_safepoint_check(); 840 } 841 842 pthread_t tid; 843 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 844 845 pthread_attr_destroy(&attr); 846 847 if (ret != 0) { 848 if (PrintMiscellaneous && (Verbose || WizardMode)) { 849 perror("pthread_create()"); 850 } 851 // Need to clean up stuff we've allocated so far 852 thread->set_osthread(NULL); 853 delete osthread; 854 if (lock) os::Linux::createThread_lock()->unlock(); 855 return false; 856 } 857 858 // Store pthread info into the OSThread 859 osthread->set_pthread_id(tid); 860 861 // Wait until child thread is either initialized or aborted 862 { 863 Monitor* sync_with_child = osthread->startThread_lock(); 864 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 865 while ((state = osthread->get_state()) == ALLOCATED) { 866 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 867 } 868 } 869 870 if (lock) { 871 os::Linux::createThread_lock()->unlock(); 872 } 873 } 874 875 // Aborted due to thread limit being reached 876 if (state == ZOMBIE) { 877 thread->set_osthread(NULL); 878 delete osthread; 879 return false; 880 } 881 882 // The thread is returned suspended (in state INITIALIZED), 883 // and is started higher up in the call chain 884 assert(state == INITIALIZED, "race condition"); 885 return true; 886 } 887 888 ///////////////////////////////////////////////////////////////////////////// 889 // attach existing thread 890 891 // bootstrap the main thread 892 bool os::create_main_thread(JavaThread* thread) { 893 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 894 return create_attached_thread(thread); 895 } 896 897 bool os::create_attached_thread(JavaThread* thread) { 898 #ifdef ASSERT 899 thread->verify_not_published(); 900 #endif 901 902 // Allocate the OSThread object 903 OSThread* osthread = new OSThread(NULL, NULL); 904 905 if (osthread == NULL) { 906 return false; 907 } 908 909 // Store pthread info into the OSThread 910 osthread->set_thread_id(os::Linux::gettid()); 911 osthread->set_pthread_id(::pthread_self()); 912 913 // initialize floating point control register 914 os::Linux::init_thread_fpu_state(); 915 916 // Initial thread state is RUNNABLE 917 osthread->set_state(RUNNABLE); 918 919 thread->set_osthread(osthread); 920 921 if (UseNUMA) { 922 int lgrp_id = os::numa_get_group_id(); 923 if (lgrp_id != -1) { 924 thread->set_lgrp_id(lgrp_id); 925 } 926 } 927 928 if (os::Linux::is_initial_thread()) { 929 // If current thread is initial thread, its stack is mapped on demand, 930 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 931 // the entire stack region to avoid SEGV in stack banging. 932 // It is also useful to get around the heap-stack-gap problem on SuSE 933 // kernel (see 4821821 for details). We first expand stack to the top 934 // of yellow zone, then enable stack yellow zone (order is significant, 935 // enabling yellow zone first will crash JVM on SuSE Linux), so there 936 // is no gap between the last two virtual memory regions. 937 938 JavaThread *jt = (JavaThread *)thread; 939 address addr = jt->stack_yellow_zone_base(); 940 assert(addr != NULL, "initialization problem?"); 941 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 942 943 osthread->set_expanding_stack(); 944 os::Linux::manually_expand_stack(jt, addr); 945 osthread->clear_expanding_stack(); 946 } 947 948 // initialize signal mask for this thread 949 // and save the caller's signal mask 950 os::Linux::hotspot_sigmask(thread); 951 952 return true; 953 } 954 955 void os::pd_start_thread(Thread* thread) { 956 OSThread * osthread = thread->osthread(); 957 assert(osthread->get_state() != INITIALIZED, "just checking"); 958 Monitor* sync_with_child = osthread->startThread_lock(); 959 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 960 sync_with_child->notify(); 961 } 962 963 // Free Linux resources related to the OSThread 964 void os::free_thread(OSThread* osthread) { 965 assert(osthread != NULL, "osthread not set"); 966 967 if (Thread::current()->osthread() == osthread) { 968 // Restore caller's signal mask 969 sigset_t sigmask = osthread->caller_sigmask(); 970 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 971 } 972 973 delete osthread; 974 } 975 976 ////////////////////////////////////////////////////////////////////////////// 977 // thread local storage 978 979 // Restore the thread pointer if the destructor is called. This is in case 980 // someone from JNI code sets up a destructor with pthread_key_create to run 981 // detachCurrentThread on thread death. Unless we restore the thread pointer we 982 // will hang or crash. When detachCurrentThread is called the key will be set 983 // to null and we will not be called again. If detachCurrentThread is never 984 // called we could loop forever depending on the pthread implementation. 985 static void restore_thread_pointer(void* p) { 986 Thread* thread = (Thread*) p; 987 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); 988 } 989 990 int os::allocate_thread_local_storage() { 991 pthread_key_t key; 992 int rslt = pthread_key_create(&key, restore_thread_pointer); 993 assert(rslt == 0, "cannot allocate thread local storage"); 994 return (int)key; 995 } 996 997 // Note: This is currently not used by VM, as we don't destroy TLS key 998 // on VM exit. 999 void os::free_thread_local_storage(int index) { 1000 int rslt = pthread_key_delete((pthread_key_t)index); 1001 assert(rslt == 0, "invalid index"); 1002 } 1003 1004 void os::thread_local_storage_at_put(int index, void* value) { 1005 int rslt = pthread_setspecific((pthread_key_t)index, value); 1006 assert(rslt == 0, "pthread_setspecific failed"); 1007 } 1008 1009 extern "C" Thread* get_thread() { 1010 return ThreadLocalStorage::thread(); 1011 } 1012 1013 ////////////////////////////////////////////////////////////////////////////// 1014 // initial thread 1015 1016 // Check if current thread is the initial thread, similar to Solaris thr_main. 1017 bool os::Linux::is_initial_thread(void) { 1018 char dummy; 1019 // If called before init complete, thread stack bottom will be null. 1020 // Can be called if fatal error occurs before initialization. 1021 if (initial_thread_stack_bottom() == NULL) return false; 1022 assert(initial_thread_stack_bottom() != NULL && 1023 initial_thread_stack_size() != 0, 1024 "os::init did not locate initial thread's stack region"); 1025 if ((address)&dummy >= initial_thread_stack_bottom() && 1026 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) { 1027 return true; 1028 } else { 1029 return false; 1030 } 1031 } 1032 1033 // Find the virtual memory area that contains addr 1034 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1035 FILE *fp = fopen("/proc/self/maps", "r"); 1036 if (fp) { 1037 address low, high; 1038 while (!feof(fp)) { 1039 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1040 if (low <= addr && addr < high) { 1041 if (vma_low) *vma_low = low; 1042 if (vma_high) *vma_high = high; 1043 fclose(fp); 1044 return true; 1045 } 1046 } 1047 for (;;) { 1048 int ch = fgetc(fp); 1049 if (ch == EOF || ch == (int)'\n') break; 1050 } 1051 } 1052 fclose(fp); 1053 } 1054 return false; 1055 } 1056 1057 // Locate initial thread stack. This special handling of initial thread stack 1058 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1059 // bogus value for initial thread. 1060 void os::Linux::capture_initial_stack(size_t max_size) { 1061 // stack size is the easy part, get it from RLIMIT_STACK 1062 size_t stack_size; 1063 struct rlimit rlim; 1064 getrlimit(RLIMIT_STACK, &rlim); 1065 stack_size = rlim.rlim_cur; 1066 1067 // 6308388: a bug in ld.so will relocate its own .data section to the 1068 // lower end of primordial stack; reduce ulimit -s value a little bit 1069 // so we won't install guard page on ld.so's data section. 1070 stack_size -= 2 * page_size(); 1071 1072 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1073 // 7.1, in both cases we will get 2G in return value. 1074 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1075 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1076 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1077 // in case other parts in glibc still assumes 2M max stack size. 1078 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1079 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1080 if (stack_size > 2 * K * K IA64_ONLY(*2)) { 1081 stack_size = 2 * K * K IA64_ONLY(*2); 1082 } 1083 // Try to figure out where the stack base (top) is. This is harder. 1084 // 1085 // When an application is started, glibc saves the initial stack pointer in 1086 // a global variable "__libc_stack_end", which is then used by system 1087 // libraries. __libc_stack_end should be pretty close to stack top. The 1088 // variable is available since the very early days. However, because it is 1089 // a private interface, it could disappear in the future. 1090 // 1091 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1092 // to __libc_stack_end, it is very close to stack top, but isn't the real 1093 // stack top. Note that /proc may not exist if VM is running as a chroot 1094 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1095 // /proc/<pid>/stat could change in the future (though unlikely). 1096 // 1097 // We try __libc_stack_end first. If that doesn't work, look for 1098 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1099 // as a hint, which should work well in most cases. 1100 1101 uintptr_t stack_start; 1102 1103 // try __libc_stack_end first 1104 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1105 if (p && *p) { 1106 stack_start = *p; 1107 } else { 1108 // see if we can get the start_stack field from /proc/self/stat 1109 FILE *fp; 1110 int pid; 1111 char state; 1112 int ppid; 1113 int pgrp; 1114 int session; 1115 int nr; 1116 int tpgrp; 1117 unsigned long flags; 1118 unsigned long minflt; 1119 unsigned long cminflt; 1120 unsigned long majflt; 1121 unsigned long cmajflt; 1122 unsigned long utime; 1123 unsigned long stime; 1124 long cutime; 1125 long cstime; 1126 long prio; 1127 long nice; 1128 long junk; 1129 long it_real; 1130 uintptr_t start; 1131 uintptr_t vsize; 1132 intptr_t rss; 1133 uintptr_t rsslim; 1134 uintptr_t scodes; 1135 uintptr_t ecode; 1136 int i; 1137 1138 // Figure what the primordial thread stack base is. Code is inspired 1139 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1140 // followed by command name surrounded by parentheses, state, etc. 1141 char stat[2048]; 1142 int statlen; 1143 1144 fp = fopen("/proc/self/stat", "r"); 1145 if (fp) { 1146 statlen = fread(stat, 1, 2047, fp); 1147 stat[statlen] = '\0'; 1148 fclose(fp); 1149 1150 // Skip pid and the command string. Note that we could be dealing with 1151 // weird command names, e.g. user could decide to rename java launcher 1152 // to "java 1.4.2 :)", then the stat file would look like 1153 // 1234 (java 1.4.2 :)) R ... ... 1154 // We don't really need to know the command string, just find the last 1155 // occurrence of ")" and then start parsing from there. See bug 4726580. 1156 char * s = strrchr(stat, ')'); 1157 1158 i = 0; 1159 if (s) { 1160 // Skip blank chars 1161 do { s++; } while (s && isspace(*s)); 1162 1163 #define _UFM UINTX_FORMAT 1164 #define _DFM INTX_FORMAT 1165 1166 // 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 1167 // 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 1168 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, 1169 &state, // 3 %c 1170 &ppid, // 4 %d 1171 &pgrp, // 5 %d 1172 &session, // 6 %d 1173 &nr, // 7 %d 1174 &tpgrp, // 8 %d 1175 &flags, // 9 %lu 1176 &minflt, // 10 %lu 1177 &cminflt, // 11 %lu 1178 &majflt, // 12 %lu 1179 &cmajflt, // 13 %lu 1180 &utime, // 14 %lu 1181 &stime, // 15 %lu 1182 &cutime, // 16 %ld 1183 &cstime, // 17 %ld 1184 &prio, // 18 %ld 1185 &nice, // 19 %ld 1186 &junk, // 20 %ld 1187 &it_real, // 21 %ld 1188 &start, // 22 UINTX_FORMAT 1189 &vsize, // 23 UINTX_FORMAT 1190 &rss, // 24 INTX_FORMAT 1191 &rsslim, // 25 UINTX_FORMAT 1192 &scodes, // 26 UINTX_FORMAT 1193 &ecode, // 27 UINTX_FORMAT 1194 &stack_start); // 28 UINTX_FORMAT 1195 } 1196 1197 #undef _UFM 1198 #undef _DFM 1199 1200 if (i != 28 - 2) { 1201 assert(false, "Bad conversion from /proc/self/stat"); 1202 // product mode - assume we are the initial thread, good luck in the 1203 // embedded case. 1204 warning("Can't detect initial thread stack location - bad conversion"); 1205 stack_start = (uintptr_t) &rlim; 1206 } 1207 } else { 1208 // For some reason we can't open /proc/self/stat (for example, running on 1209 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1210 // most cases, so don't abort: 1211 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1212 stack_start = (uintptr_t) &rlim; 1213 } 1214 } 1215 1216 // Now we have a pointer (stack_start) very close to the stack top, the 1217 // next thing to do is to figure out the exact location of stack top. We 1218 // can find out the virtual memory area that contains stack_start by 1219 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1220 // and its upper limit is the real stack top. (again, this would fail if 1221 // running inside chroot, because /proc may not exist.) 1222 1223 uintptr_t stack_top; 1224 address low, high; 1225 if (find_vma((address)stack_start, &low, &high)) { 1226 // success, "high" is the true stack top. (ignore "low", because initial 1227 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1228 stack_top = (uintptr_t)high; 1229 } else { 1230 // failed, likely because /proc/self/maps does not exist 1231 warning("Can't detect initial thread stack location - find_vma failed"); 1232 // best effort: stack_start is normally within a few pages below the real 1233 // stack top, use it as stack top, and reduce stack size so we won't put 1234 // guard page outside stack. 1235 stack_top = stack_start; 1236 stack_size -= 16 * page_size(); 1237 } 1238 1239 // stack_top could be partially down the page so align it 1240 stack_top = align_size_up(stack_top, page_size()); 1241 1242 if (max_size && stack_size > max_size) { 1243 _initial_thread_stack_size = max_size; 1244 } else { 1245 _initial_thread_stack_size = stack_size; 1246 } 1247 1248 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1249 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1250 } 1251 1252 //////////////////////////////////////////////////////////////////////////////// 1253 // time support 1254 1255 // Time since start-up in seconds to a fine granularity. 1256 // Used by VMSelfDestructTimer and the MemProfiler. 1257 double os::elapsedTime() { 1258 1259 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution 1260 } 1261 1262 jlong os::elapsed_counter() { 1263 return javaTimeNanos() - initial_time_count; 1264 } 1265 1266 jlong os::elapsed_frequency() { 1267 return NANOSECS_PER_SEC; // nanosecond resolution 1268 } 1269 1270 bool os::supports_vtime() { return true; } 1271 bool os::enable_vtime() { return false; } 1272 bool os::vtime_enabled() { return false; } 1273 1274 double os::elapsedVTime() { 1275 struct rusage usage; 1276 int retval = getrusage(RUSAGE_THREAD, &usage); 1277 if (retval == 0) { 1278 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); 1279 } else { 1280 // better than nothing, but not much 1281 return elapsedTime(); 1282 } 1283 } 1284 1285 jlong os::javaTimeMillis() { 1286 timeval time; 1287 int status = gettimeofday(&time, NULL); 1288 assert(status != -1, "linux error"); 1289 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1290 } 1291 1292 void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) { 1293 timeval time; 1294 int status = gettimeofday(&time, NULL); 1295 assert(status != -1, "linux error"); 1296 seconds = jlong(time.tv_sec); 1297 nanos = jlong(time.tv_usec) * 1000; 1298 } 1299 1300 1301 #ifndef CLOCK_MONOTONIC 1302 #define CLOCK_MONOTONIC (1) 1303 #endif 1304 1305 void os::Linux::clock_init() { 1306 // we do dlopen's in this particular order due to bug in linux 1307 // dynamical loader (see 6348968) leading to crash on exit 1308 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1309 if (handle == NULL) { 1310 handle = dlopen("librt.so", RTLD_LAZY); 1311 } 1312 1313 if (handle) { 1314 int (*clock_getres_func)(clockid_t, struct timespec*) = 1315 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1316 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1317 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1318 if (clock_getres_func && clock_gettime_func) { 1319 // See if monotonic clock is supported by the kernel. Note that some 1320 // early implementations simply return kernel jiffies (updated every 1321 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1322 // for nano time (though the monotonic property is still nice to have). 1323 // It's fixed in newer kernels, however clock_getres() still returns 1324 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1325 // resolution for now. Hopefully as people move to new kernels, this 1326 // won't be a problem. 1327 struct timespec res; 1328 struct timespec tp; 1329 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1330 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1331 // yes, monotonic clock is supported 1332 _clock_gettime = clock_gettime_func; 1333 return; 1334 } else { 1335 // close librt if there is no monotonic clock 1336 dlclose(handle); 1337 } 1338 } 1339 } 1340 warning("No monotonic clock was available - timed services may " \ 1341 "be adversely affected if the time-of-day clock changes"); 1342 } 1343 1344 #ifndef SYS_clock_getres 1345 #if defined(IA32) || defined(AMD64) 1346 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1347 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1348 #else 1349 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time" 1350 #define sys_clock_getres(x,y) -1 1351 #endif 1352 #else 1353 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1354 #endif 1355 1356 void os::Linux::fast_thread_clock_init() { 1357 if (!UseLinuxPosixThreadCPUClocks) { 1358 return; 1359 } 1360 clockid_t clockid; 1361 struct timespec tp; 1362 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1363 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1364 1365 // Switch to using fast clocks for thread cpu time if 1366 // the sys_clock_getres() returns 0 error code. 1367 // Note, that some kernels may support the current thread 1368 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1369 // returned by the pthread_getcpuclockid(). 1370 // If the fast Posix clocks are supported then the sys_clock_getres() 1371 // must return at least tp.tv_sec == 0 which means a resolution 1372 // better than 1 sec. This is extra check for reliability. 1373 1374 if (pthread_getcpuclockid_func && 1375 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1376 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1377 _supports_fast_thread_cpu_time = true; 1378 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1379 } 1380 } 1381 1382 jlong os::javaTimeNanos() { 1383 if (os::supports_monotonic_clock()) { 1384 struct timespec tp; 1385 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1386 assert(status == 0, "gettime error"); 1387 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1388 return result; 1389 } else { 1390 timeval time; 1391 int status = gettimeofday(&time, NULL); 1392 assert(status != -1, "linux error"); 1393 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1394 return 1000 * usecs; 1395 } 1396 } 1397 1398 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1399 if (os::supports_monotonic_clock()) { 1400 info_ptr->max_value = ALL_64_BITS; 1401 1402 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1403 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1404 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1405 } else { 1406 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1407 info_ptr->max_value = ALL_64_BITS; 1408 1409 // gettimeofday is a real time clock so it skips 1410 info_ptr->may_skip_backward = true; 1411 info_ptr->may_skip_forward = true; 1412 } 1413 1414 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1415 } 1416 1417 // Return the real, user, and system times in seconds from an 1418 // arbitrary fixed point in the past. 1419 bool os::getTimesSecs(double* process_real_time, 1420 double* process_user_time, 1421 double* process_system_time) { 1422 struct tms ticks; 1423 clock_t real_ticks = times(&ticks); 1424 1425 if (real_ticks == (clock_t) (-1)) { 1426 return false; 1427 } else { 1428 double ticks_per_second = (double) clock_tics_per_sec; 1429 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1430 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1431 *process_real_time = ((double) real_ticks) / ticks_per_second; 1432 1433 return true; 1434 } 1435 } 1436 1437 1438 char * os::local_time_string(char *buf, size_t buflen) { 1439 struct tm t; 1440 time_t long_time; 1441 time(&long_time); 1442 localtime_r(&long_time, &t); 1443 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1444 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1445 t.tm_hour, t.tm_min, t.tm_sec); 1446 return buf; 1447 } 1448 1449 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1450 return localtime_r(clock, res); 1451 } 1452 1453 //////////////////////////////////////////////////////////////////////////////// 1454 // runtime exit support 1455 1456 // Note: os::shutdown() might be called very early during initialization, or 1457 // called from signal handler. Before adding something to os::shutdown(), make 1458 // sure it is async-safe and can handle partially initialized VM. 1459 void os::shutdown() { 1460 1461 // allow PerfMemory to attempt cleanup of any persistent resources 1462 perfMemory_exit(); 1463 1464 // needs to remove object in file system 1465 AttachListener::abort(); 1466 1467 // flush buffered output, finish log files 1468 ostream_abort(); 1469 1470 // Check for abort hook 1471 abort_hook_t abort_hook = Arguments::abort_hook(); 1472 if (abort_hook != NULL) { 1473 abort_hook(); 1474 } 1475 1476 } 1477 1478 // Note: os::abort() might be called very early during initialization, or 1479 // called from signal handler. Before adding something to os::abort(), make 1480 // sure it is async-safe and can handle partially initialized VM. 1481 void os::abort(bool dump_core, void* siginfo, void* context) { 1482 os::shutdown(); 1483 if (dump_core) { 1484 #ifndef PRODUCT 1485 fdStream out(defaultStream::output_fd()); 1486 out.print_raw("Current thread is "); 1487 char buf[16]; 1488 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1489 out.print_raw_cr(buf); 1490 out.print_raw_cr("Dumping core ..."); 1491 #endif 1492 ::abort(); // dump core 1493 } 1494 1495 ::exit(1); 1496 } 1497 1498 // Die immediately, no exit hook, no abort hook, no cleanup. 1499 void os::die() { 1500 // _exit() on LinuxThreads only kills current thread 1501 ::abort(); 1502 } 1503 1504 1505 // This method is a copy of JDK's sysGetLastErrorString 1506 // from src/solaris/hpi/src/system_md.c 1507 1508 size_t os::lasterror(char *buf, size_t len) { 1509 if (errno == 0) return 0; 1510 1511 const char *s = ::strerror(errno); 1512 size_t n = ::strlen(s); 1513 if (n >= len) { 1514 n = len - 1; 1515 } 1516 ::strncpy(buf, s, n); 1517 buf[n] = '\0'; 1518 return n; 1519 } 1520 1521 intx os::current_thread_id() { return (intx)pthread_self(); } 1522 int os::current_process_id() { 1523 1524 // Under the old linux thread library, linux gives each thread 1525 // its own process id. Because of this each thread will return 1526 // a different pid if this method were to return the result 1527 // of getpid(2). Linux provides no api that returns the pid 1528 // of the launcher thread for the vm. This implementation 1529 // returns a unique pid, the pid of the launcher thread 1530 // that starts the vm 'process'. 1531 1532 // Under the NPTL, getpid() returns the same pid as the 1533 // launcher thread rather than a unique pid per thread. 1534 // Use gettid() if you want the old pre NPTL behaviour. 1535 1536 // if you are looking for the result of a call to getpid() that 1537 // returns a unique pid for the calling thread, then look at the 1538 // OSThread::thread_id() method in osThread_linux.hpp file 1539 1540 return (int)(_initial_pid ? _initial_pid : getpid()); 1541 } 1542 1543 // DLL functions 1544 1545 const char* os::dll_file_extension() { return ".so"; } 1546 1547 // This must be hard coded because it's the system's temporary 1548 // directory not the java application's temp directory, ala java.io.tmpdir. 1549 const char* os::get_temp_directory() { return "/tmp"; } 1550 1551 static bool file_exists(const char* filename) { 1552 struct stat statbuf; 1553 if (filename == NULL || strlen(filename) == 0) { 1554 return false; 1555 } 1556 return os::stat(filename, &statbuf) == 0; 1557 } 1558 1559 bool os::dll_build_name(char* buffer, size_t buflen, 1560 const char* pname, const char* fname) { 1561 bool retval = false; 1562 // Copied from libhpi 1563 const size_t pnamelen = pname ? strlen(pname) : 0; 1564 1565 // Return error on buffer overflow. 1566 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1567 return retval; 1568 } 1569 1570 if (pnamelen == 0) { 1571 snprintf(buffer, buflen, "lib%s.so", fname); 1572 retval = true; 1573 } else if (strchr(pname, *os::path_separator()) != NULL) { 1574 int n; 1575 char** pelements = split_path(pname, &n); 1576 if (pelements == NULL) { 1577 return false; 1578 } 1579 for (int i = 0; i < n; i++) { 1580 // Really shouldn't be NULL, but check can't hurt 1581 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1582 continue; // skip the empty path values 1583 } 1584 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1585 if (file_exists(buffer)) { 1586 retval = true; 1587 break; 1588 } 1589 } 1590 // release the storage 1591 for (int i = 0; i < n; i++) { 1592 if (pelements[i] != NULL) { 1593 FREE_C_HEAP_ARRAY(char, pelements[i]); 1594 } 1595 } 1596 if (pelements != NULL) { 1597 FREE_C_HEAP_ARRAY(char*, pelements); 1598 } 1599 } else { 1600 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1601 retval = true; 1602 } 1603 return retval; 1604 } 1605 1606 // check if addr is inside libjvm.so 1607 bool os::address_is_in_vm(address addr) { 1608 static address libjvm_base_addr; 1609 Dl_info dlinfo; 1610 1611 if (libjvm_base_addr == NULL) { 1612 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1613 libjvm_base_addr = (address)dlinfo.dli_fbase; 1614 } 1615 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1616 } 1617 1618 if (dladdr((void *)addr, &dlinfo) != 0) { 1619 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1620 } 1621 1622 return false; 1623 } 1624 1625 bool os::dll_address_to_function_name(address addr, char *buf, 1626 int buflen, int *offset) { 1627 // buf is not optional, but offset is optional 1628 assert(buf != NULL, "sanity check"); 1629 1630 Dl_info dlinfo; 1631 1632 if (dladdr((void*)addr, &dlinfo) != 0) { 1633 // see if we have a matching symbol 1634 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1635 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1636 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1637 } 1638 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1639 return true; 1640 } 1641 // no matching symbol so try for just file info 1642 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1643 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1644 buf, buflen, offset, dlinfo.dli_fname)) { 1645 return true; 1646 } 1647 } 1648 } 1649 1650 buf[0] = '\0'; 1651 if (offset != NULL) *offset = -1; 1652 return false; 1653 } 1654 1655 struct _address_to_library_name { 1656 address addr; // input : memory address 1657 size_t buflen; // size of fname 1658 char* fname; // output: library name 1659 address base; // library base addr 1660 }; 1661 1662 static int address_to_library_name_callback(struct dl_phdr_info *info, 1663 size_t size, void *data) { 1664 int i; 1665 bool found = false; 1666 address libbase = NULL; 1667 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1668 1669 // iterate through all loadable segments 1670 for (i = 0; i < info->dlpi_phnum; i++) { 1671 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1672 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1673 // base address of a library is the lowest address of its loaded 1674 // segments. 1675 if (libbase == NULL || libbase > segbase) { 1676 libbase = segbase; 1677 } 1678 // see if 'addr' is within current segment 1679 if (segbase <= d->addr && 1680 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1681 found = true; 1682 } 1683 } 1684 } 1685 1686 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1687 // so dll_address_to_library_name() can fall through to use dladdr() which 1688 // can figure out executable name from argv[0]. 1689 if (found && info->dlpi_name && info->dlpi_name[0]) { 1690 d->base = libbase; 1691 if (d->fname) { 1692 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1693 } 1694 return 1; 1695 } 1696 return 0; 1697 } 1698 1699 bool os::dll_address_to_library_name(address addr, char* buf, 1700 int buflen, int* offset) { 1701 // buf is not optional, but offset is optional 1702 assert(buf != NULL, "sanity check"); 1703 1704 Dl_info dlinfo; 1705 struct _address_to_library_name data; 1706 1707 // There is a bug in old glibc dladdr() implementation that it could resolve 1708 // to wrong library name if the .so file has a base address != NULL. Here 1709 // we iterate through the program headers of all loaded libraries to find 1710 // out which library 'addr' really belongs to. This workaround can be 1711 // removed once the minimum requirement for glibc is moved to 2.3.x. 1712 data.addr = addr; 1713 data.fname = buf; 1714 data.buflen = buflen; 1715 data.base = NULL; 1716 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1717 1718 if (rslt) { 1719 // buf already contains library name 1720 if (offset) *offset = addr - data.base; 1721 return true; 1722 } 1723 if (dladdr((void*)addr, &dlinfo) != 0) { 1724 if (dlinfo.dli_fname != NULL) { 1725 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1726 } 1727 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1728 *offset = addr - (address)dlinfo.dli_fbase; 1729 } 1730 return true; 1731 } 1732 1733 buf[0] = '\0'; 1734 if (offset) *offset = -1; 1735 return false; 1736 } 1737 1738 // Loads .dll/.so and 1739 // in case of error it checks if .dll/.so was built for the 1740 // same architecture as Hotspot is running on 1741 1742 1743 // Remember the stack's state. The Linux dynamic linker will change 1744 // the stack to 'executable' at most once, so we must safepoint only once. 1745 bool os::Linux::_stack_is_executable = false; 1746 1747 // VM operation that loads a library. This is necessary if stack protection 1748 // of the Java stacks can be lost during loading the library. If we 1749 // do not stop the Java threads, they can stack overflow before the stacks 1750 // are protected again. 1751 class VM_LinuxDllLoad: public VM_Operation { 1752 private: 1753 const char *_filename; 1754 char *_ebuf; 1755 int _ebuflen; 1756 void *_lib; 1757 public: 1758 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1759 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1760 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1761 void doit() { 1762 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1763 os::Linux::_stack_is_executable = true; 1764 } 1765 void* loaded_library() { return _lib; } 1766 }; 1767 1768 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) { 1769 void * result = NULL; 1770 bool load_attempted = false; 1771 1772 // Check whether the library to load might change execution rights 1773 // of the stack. If they are changed, the protection of the stack 1774 // guard pages will be lost. We need a safepoint to fix this. 1775 // 1776 // See Linux man page execstack(8) for more info. 1777 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1778 ElfFile ef(filename); 1779 if (!ef.specifies_noexecstack()) { 1780 if (!is_init_completed()) { 1781 os::Linux::_stack_is_executable = true; 1782 // This is OK - No Java threads have been created yet, and hence no 1783 // stack guard pages to fix. 1784 // 1785 // This should happen only when you are building JDK7 using a very 1786 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1787 // 1788 // Dynamic loader will make all stacks executable after 1789 // this function returns, and will not do that again. 1790 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1791 } else { 1792 warning("You have loaded library %s which might have disabled stack guard. " 1793 "The VM will try to fix the stack guard now.\n" 1794 "It's highly recommended that you fix the library with " 1795 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1796 filename); 1797 1798 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1799 JavaThread *jt = JavaThread::current(); 1800 if (jt->thread_state() != _thread_in_native) { 1801 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1802 // that requires ExecStack. Cannot enter safe point. Let's give up. 1803 warning("Unable to fix stack guard. Giving up."); 1804 } else { 1805 if (!LoadExecStackDllInVMThread) { 1806 // This is for the case where the DLL has an static 1807 // constructor function that executes JNI code. We cannot 1808 // load such DLLs in the VMThread. 1809 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1810 } 1811 1812 ThreadInVMfromNative tiv(jt); 1813 debug_only(VMNativeEntryWrapper vew;) 1814 1815 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1816 VMThread::execute(&op); 1817 if (LoadExecStackDllInVMThread) { 1818 result = op.loaded_library(); 1819 } 1820 load_attempted = true; 1821 } 1822 } 1823 } 1824 } 1825 1826 if (!load_attempted) { 1827 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1828 } 1829 1830 if (result != NULL) { 1831 // Successful loading 1832 return result; 1833 } 1834 1835 Elf32_Ehdr elf_head; 1836 int diag_msg_max_length=ebuflen-strlen(ebuf); 1837 char* diag_msg_buf=ebuf+strlen(ebuf); 1838 1839 if (diag_msg_max_length==0) { 1840 // No more space in ebuf for additional diagnostics message 1841 return NULL; 1842 } 1843 1844 1845 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1846 1847 if (file_descriptor < 0) { 1848 // Can't open library, report dlerror() message 1849 return NULL; 1850 } 1851 1852 bool failed_to_read_elf_head= 1853 (sizeof(elf_head)!= 1854 (::read(file_descriptor, &elf_head,sizeof(elf_head)))); 1855 1856 ::close(file_descriptor); 1857 if (failed_to_read_elf_head) { 1858 // file i/o error - report dlerror() msg 1859 return NULL; 1860 } 1861 1862 typedef struct { 1863 Elf32_Half code; // Actual value as defined in elf.h 1864 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1865 char elf_class; // 32 or 64 bit 1866 char endianess; // MSB or LSB 1867 char* name; // String representation 1868 } arch_t; 1869 1870 #ifndef EM_486 1871 #define EM_486 6 /* Intel 80486 */ 1872 #endif 1873 #ifndef EM_AARCH64 1874 #define EM_AARCH64 183 /* ARM AARCH64 */ 1875 #endif 1876 1877 static const arch_t arch_array[]={ 1878 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1879 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1880 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1881 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1882 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1883 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1884 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1885 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1886 #if defined(VM_LITTLE_ENDIAN) 1887 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"}, 1888 #else 1889 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1890 #endif 1891 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1892 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1893 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1894 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1895 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1896 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1897 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}, 1898 {EM_AARCH64, EM_AARCH64, ELFCLASS64, ELFDATA2LSB, (char*)"AARCH64"}, 1899 }; 1900 1901 #if (defined IA32) 1902 static Elf32_Half running_arch_code=EM_386; 1903 #elif (defined AMD64) 1904 static Elf32_Half running_arch_code=EM_X86_64; 1905 #elif (defined IA64) 1906 static Elf32_Half running_arch_code=EM_IA_64; 1907 #elif (defined __sparc) && (defined _LP64) 1908 static Elf32_Half running_arch_code=EM_SPARCV9; 1909 #elif (defined __sparc) && (!defined _LP64) 1910 static Elf32_Half running_arch_code=EM_SPARC; 1911 #elif (defined __powerpc64__) 1912 static Elf32_Half running_arch_code=EM_PPC64; 1913 #elif (defined __powerpc__) 1914 static Elf32_Half running_arch_code=EM_PPC; 1915 #elif (defined ARM) 1916 static Elf32_Half running_arch_code=EM_ARM; 1917 #elif (defined S390) 1918 static Elf32_Half running_arch_code=EM_S390; 1919 #elif (defined ALPHA) 1920 static Elf32_Half running_arch_code=EM_ALPHA; 1921 #elif (defined MIPSEL) 1922 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1923 #elif (defined PARISC) 1924 static Elf32_Half running_arch_code=EM_PARISC; 1925 #elif (defined MIPS) 1926 static Elf32_Half running_arch_code=EM_MIPS; 1927 #elif (defined M68K) 1928 static Elf32_Half running_arch_code=EM_68K; 1929 #elif (defined AARCH64) 1930 static Elf32_Half running_arch_code=EM_AARCH64; 1931 #else 1932 #error Method os::dll_load requires that one of following is defined:\ 1933 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K, AARCH64 1934 #endif 1935 1936 // Identify compatability class for VM's architecture and library's architecture 1937 // Obtain string descriptions for architectures 1938 1939 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1940 int running_arch_index=-1; 1941 1942 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) { 1943 if (running_arch_code == arch_array[i].code) { 1944 running_arch_index = i; 1945 } 1946 if (lib_arch.code == arch_array[i].code) { 1947 lib_arch.compat_class = arch_array[i].compat_class; 1948 lib_arch.name = arch_array[i].name; 1949 } 1950 } 1951 1952 assert(running_arch_index != -1, 1953 "Didn't find running architecture code (running_arch_code) in arch_array"); 1954 if (running_arch_index == -1) { 1955 // Even though running architecture detection failed 1956 // we may still continue with reporting dlerror() message 1957 return NULL; 1958 } 1959 1960 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1961 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1962 return NULL; 1963 } 1964 1965 #ifndef S390 1966 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 1967 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 1968 return NULL; 1969 } 1970 #endif // !S390 1971 1972 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 1973 if (lib_arch.name!=NULL) { 1974 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1975 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 1976 lib_arch.name, arch_array[running_arch_index].name); 1977 } else { 1978 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1979 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 1980 lib_arch.code, 1981 arch_array[running_arch_index].name); 1982 } 1983 } 1984 1985 return NULL; 1986 } 1987 1988 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, 1989 int ebuflen) { 1990 void * result = ::dlopen(filename, RTLD_LAZY); 1991 if (result == NULL) { 1992 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 1993 ebuf[ebuflen-1] = '\0'; 1994 } 1995 return result; 1996 } 1997 1998 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, 1999 int ebuflen) { 2000 void * result = NULL; 2001 if (LoadExecStackDllInVMThread) { 2002 result = dlopen_helper(filename, ebuf, ebuflen); 2003 } 2004 2005 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2006 // library that requires an executable stack, or which does not have this 2007 // stack attribute set, dlopen changes the stack attribute to executable. The 2008 // read protection of the guard pages gets lost. 2009 // 2010 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2011 // may have been queued at the same time. 2012 2013 if (!_stack_is_executable) { 2014 JavaThread *jt = Threads::first(); 2015 2016 while (jt) { 2017 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2018 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2019 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2020 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2021 warning("Attempt to reguard stack yellow zone failed."); 2022 } 2023 } 2024 jt = jt->next(); 2025 } 2026 } 2027 2028 return result; 2029 } 2030 2031 void* os::dll_lookup(void* handle, const char* name) { 2032 void* res = dlsym(handle, name); 2033 return res; 2034 } 2035 2036 void* os::get_default_process_handle() { 2037 return (void*)::dlopen(NULL, RTLD_LAZY); 2038 } 2039 2040 static bool _print_ascii_file(const char* filename, outputStream* st) { 2041 int fd = ::open(filename, O_RDONLY); 2042 if (fd == -1) { 2043 return false; 2044 } 2045 2046 char buf[32]; 2047 int bytes; 2048 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2049 st->print_raw(buf, bytes); 2050 } 2051 2052 ::close(fd); 2053 2054 return true; 2055 } 2056 2057 void os::print_dll_info(outputStream *st) { 2058 st->print_cr("Dynamic libraries:"); 2059 2060 char fname[32]; 2061 pid_t pid = os::Linux::gettid(); 2062 2063 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2064 2065 if (!_print_ascii_file(fname, st)) { 2066 st->print("Can not get library information for pid = %d\n", pid); 2067 } 2068 } 2069 2070 int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) { 2071 FILE *procmapsFile = NULL; 2072 2073 // Open the procfs maps file for the current process 2074 if ((procmapsFile = fopen("/proc/self/maps", "r")) != NULL) { 2075 // Allocate PATH_MAX for file name plus a reasonable size for other fields. 2076 char line[PATH_MAX + 100]; 2077 2078 // Read line by line from 'file' 2079 while (fgets(line, sizeof(line), procmapsFile) != NULL) { 2080 u8 base, top, offset, inode; 2081 char permissions[5]; 2082 char device[6]; 2083 char name[PATH_MAX + 1]; 2084 2085 // Parse fields from line 2086 sscanf(line, "%lx-%lx %4s %lx %5s %ld %s", &base, &top, permissions, &offset, device, &inode, name); 2087 2088 // Filter by device id '00:00' so that we only get file system mapped files. 2089 if (strcmp(device, "00:00") != 0) { 2090 2091 // Call callback with the fields of interest 2092 if(callback(name, (address)base, (address)top, param)) { 2093 // Oops abort, callback aborted 2094 fclose(procmapsFile); 2095 return 1; 2096 } 2097 } 2098 } 2099 fclose(procmapsFile); 2100 } 2101 return 0; 2102 } 2103 2104 void os::print_os_info_brief(outputStream* st) { 2105 os::Linux::print_distro_info(st); 2106 2107 os::Posix::print_uname_info(st); 2108 2109 os::Linux::print_libversion_info(st); 2110 2111 } 2112 2113 void os::print_os_info(outputStream* st) { 2114 st->print("OS:"); 2115 2116 os::Linux::print_distro_info(st); 2117 2118 os::Posix::print_uname_info(st); 2119 2120 // Print warning if unsafe chroot environment detected 2121 if (unsafe_chroot_detected) { 2122 st->print("WARNING!! "); 2123 st->print_cr("%s", unstable_chroot_error); 2124 } 2125 2126 os::Linux::print_libversion_info(st); 2127 2128 os::Posix::print_rlimit_info(st); 2129 2130 os::Posix::print_load_average(st); 2131 2132 os::Linux::print_full_memory_info(st); 2133 } 2134 2135 // Try to identify popular distros. 2136 // Most Linux distributions have a /etc/XXX-release file, which contains 2137 // the OS version string. Newer Linux distributions have a /etc/lsb-release 2138 // file that also contains the OS version string. Some have more than one 2139 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2140 // /etc/redhat-release.), so the order is important. 2141 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2142 // their own specific XXX-release file as well as a redhat-release file. 2143 // Because of this the XXX-release file needs to be searched for before the 2144 // redhat-release file. 2145 // Since Red Hat has a lsb-release file that is not very descriptive the 2146 // search for redhat-release needs to be before lsb-release. 2147 // Since the lsb-release file is the new standard it needs to be searched 2148 // before the older style release files. 2149 // Searching system-release (Red Hat) and os-release (other Linuxes) are a 2150 // next to last resort. The os-release file is a new standard that contains 2151 // distribution information and the system-release file seems to be an old 2152 // standard that has been replaced by the lsb-release and os-release files. 2153 // Searching for the debian_version file is the last resort. It contains 2154 // an informative string like "6.0.6" or "wheezy/sid". Because of this 2155 // "Debian " is printed before the contents of the debian_version file. 2156 void os::Linux::print_distro_info(outputStream* st) { 2157 if (!_print_ascii_file("/etc/oracle-release", st) && 2158 !_print_ascii_file("/etc/mandriva-release", st) && 2159 !_print_ascii_file("/etc/mandrake-release", st) && 2160 !_print_ascii_file("/etc/sun-release", st) && 2161 !_print_ascii_file("/etc/redhat-release", st) && 2162 !_print_ascii_file("/etc/lsb-release", st) && 2163 !_print_ascii_file("/etc/SuSE-release", st) && 2164 !_print_ascii_file("/etc/turbolinux-release", st) && 2165 !_print_ascii_file("/etc/gentoo-release", st) && 2166 !_print_ascii_file("/etc/ltib-release", st) && 2167 !_print_ascii_file("/etc/angstrom-version", st) && 2168 !_print_ascii_file("/etc/system-release", st) && 2169 !_print_ascii_file("/etc/os-release", st)) { 2170 2171 if (file_exists("/etc/debian_version")) { 2172 st->print("Debian "); 2173 _print_ascii_file("/etc/debian_version", st); 2174 } else { 2175 st->print("Linux"); 2176 } 2177 } 2178 st->cr(); 2179 } 2180 2181 void os::Linux::print_libversion_info(outputStream* st) { 2182 // libc, pthread 2183 st->print("libc:"); 2184 st->print("%s ", os::Linux::glibc_version()); 2185 st->print("%s ", os::Linux::libpthread_version()); 2186 if (os::Linux::is_LinuxThreads()) { 2187 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2188 } 2189 st->cr(); 2190 } 2191 2192 void os::Linux::print_full_memory_info(outputStream* st) { 2193 st->print("\n/proc/meminfo:\n"); 2194 _print_ascii_file("/proc/meminfo", st); 2195 st->cr(); 2196 } 2197 2198 void os::print_memory_info(outputStream* st) { 2199 2200 st->print("Memory:"); 2201 st->print(" %dk page", os::vm_page_size()>>10); 2202 2203 // values in struct sysinfo are "unsigned long" 2204 struct sysinfo si; 2205 sysinfo(&si); 2206 2207 st->print(", physical " UINT64_FORMAT "k", 2208 os::physical_memory() >> 10); 2209 st->print("(" UINT64_FORMAT "k free)", 2210 os::available_memory() >> 10); 2211 st->print(", swap " UINT64_FORMAT "k", 2212 ((jlong)si.totalswap * si.mem_unit) >> 10); 2213 st->print("(" UINT64_FORMAT "k free)", 2214 ((jlong)si.freeswap * si.mem_unit) >> 10); 2215 st->cr(); 2216 } 2217 2218 void os::pd_print_cpu_info(outputStream* st) { 2219 st->print("\n/proc/cpuinfo:\n"); 2220 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2221 st->print(" <Not Available>"); 2222 } 2223 st->cr(); 2224 } 2225 2226 void os::print_siginfo(outputStream* st, void* siginfo) { 2227 const siginfo_t* si = (const siginfo_t*)siginfo; 2228 2229 os::Posix::print_siginfo_brief(st, si); 2230 #if INCLUDE_CDS 2231 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2232 UseSharedSpaces) { 2233 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2234 if (mapinfo->is_in_shared_space(si->si_addr)) { 2235 st->print("\n\nError accessing class data sharing archive." \ 2236 " Mapped file inaccessible during execution, " \ 2237 " possible disk/network problem."); 2238 } 2239 } 2240 #endif 2241 st->cr(); 2242 } 2243 2244 2245 static void print_signal_handler(outputStream* st, int sig, 2246 char* buf, size_t buflen); 2247 2248 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2249 st->print_cr("Signal Handlers:"); 2250 print_signal_handler(st, SIGSEGV, buf, buflen); 2251 print_signal_handler(st, SIGBUS , buf, buflen); 2252 print_signal_handler(st, SIGFPE , buf, buflen); 2253 print_signal_handler(st, SIGPIPE, buf, buflen); 2254 print_signal_handler(st, SIGXFSZ, buf, buflen); 2255 print_signal_handler(st, SIGILL , buf, buflen); 2256 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2257 print_signal_handler(st, SR_signum, buf, buflen); 2258 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2259 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2260 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2261 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2262 #if defined(PPC64) 2263 print_signal_handler(st, SIGTRAP, buf, buflen); 2264 #endif 2265 } 2266 2267 static char saved_jvm_path[MAXPATHLEN] = {0}; 2268 2269 // Find the full path to the current module, libjvm.so 2270 void os::jvm_path(char *buf, jint buflen) { 2271 // Error checking. 2272 if (buflen < MAXPATHLEN) { 2273 assert(false, "must use a large-enough buffer"); 2274 buf[0] = '\0'; 2275 return; 2276 } 2277 // Lazy resolve the path to current module. 2278 if (saved_jvm_path[0] != 0) { 2279 strcpy(buf, saved_jvm_path); 2280 return; 2281 } 2282 2283 char dli_fname[MAXPATHLEN]; 2284 bool ret = dll_address_to_library_name( 2285 CAST_FROM_FN_PTR(address, os::jvm_path), 2286 dli_fname, sizeof(dli_fname), NULL); 2287 assert(ret, "cannot locate libjvm"); 2288 char *rp = NULL; 2289 if (ret && dli_fname[0] != '\0') { 2290 rp = realpath(dli_fname, buf); 2291 } 2292 if (rp == NULL) { 2293 return; 2294 } 2295 2296 if (Arguments::sun_java_launcher_is_altjvm()) { 2297 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical 2298 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". 2299 // If "/jre/lib/" appears at the right place in the string, then 2300 // assume we are installed in a JDK and we're done. Otherwise, check 2301 // for a JAVA_HOME environment variable and fix up the path so it 2302 // looks like libjvm.so is installed there (append a fake suffix 2303 // hotspot/libjvm.so). 2304 const char *p = buf + strlen(buf) - 1; 2305 for (int count = 0; p > buf && count < 5; ++count) { 2306 for (--p; p > buf && *p != '/'; --p) 2307 /* empty */ ; 2308 } 2309 2310 if (strncmp(p, "/jre/lib/", 9) != 0) { 2311 // Look for JAVA_HOME in the environment. 2312 char* java_home_var = ::getenv("JAVA_HOME"); 2313 if (java_home_var != NULL && java_home_var[0] != 0) { 2314 char* jrelib_p; 2315 int len; 2316 2317 // Check the current module name "libjvm.so". 2318 p = strrchr(buf, '/'); 2319 if (p == NULL) { 2320 return; 2321 } 2322 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2323 2324 rp = realpath(java_home_var, buf); 2325 if (rp == NULL) { 2326 return; 2327 } 2328 2329 // determine if this is a legacy image or modules image 2330 // modules image doesn't have "jre" subdirectory 2331 len = strlen(buf); 2332 assert(len < buflen, "Ran out of buffer room"); 2333 jrelib_p = buf + len; 2334 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2335 if (0 != access(buf, F_OK)) { 2336 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2337 } 2338 2339 if (0 == access(buf, F_OK)) { 2340 // Use current module name "libjvm.so" 2341 len = strlen(buf); 2342 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2343 } else { 2344 // Go back to path of .so 2345 rp = realpath(dli_fname, buf); 2346 if (rp == NULL) { 2347 return; 2348 } 2349 } 2350 } 2351 } 2352 } 2353 2354 strncpy(saved_jvm_path, buf, MAXPATHLEN); 2355 saved_jvm_path[MAXPATHLEN - 1] = '\0'; 2356 } 2357 2358 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2359 // no prefix required, not even "_" 2360 } 2361 2362 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2363 // no suffix required 2364 } 2365 2366 //////////////////////////////////////////////////////////////////////////////// 2367 // sun.misc.Signal support 2368 2369 static volatile jint sigint_count = 0; 2370 2371 static void UserHandler(int sig, void *siginfo, void *context) { 2372 // 4511530 - sem_post is serialized and handled by the manager thread. When 2373 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2374 // don't want to flood the manager thread with sem_post requests. 2375 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) { 2376 return; 2377 } 2378 2379 // Ctrl-C is pressed during error reporting, likely because the error 2380 // handler fails to abort. Let VM die immediately. 2381 if (sig == SIGINT && is_error_reported()) { 2382 os::die(); 2383 } 2384 2385 os::signal_notify(sig); 2386 } 2387 2388 void* os::user_handler() { 2389 return CAST_FROM_FN_PTR(void*, UserHandler); 2390 } 2391 2392 class Semaphore : public StackObj { 2393 public: 2394 Semaphore(); 2395 ~Semaphore(); 2396 void signal(); 2397 void wait(); 2398 bool trywait(); 2399 bool timedwait(unsigned int sec, int nsec); 2400 private: 2401 sem_t _semaphore; 2402 }; 2403 2404 Semaphore::Semaphore() { 2405 sem_init(&_semaphore, 0, 0); 2406 } 2407 2408 Semaphore::~Semaphore() { 2409 sem_destroy(&_semaphore); 2410 } 2411 2412 void Semaphore::signal() { 2413 sem_post(&_semaphore); 2414 } 2415 2416 void Semaphore::wait() { 2417 sem_wait(&_semaphore); 2418 } 2419 2420 bool Semaphore::trywait() { 2421 return sem_trywait(&_semaphore) == 0; 2422 } 2423 2424 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2425 2426 struct timespec ts; 2427 // Semaphore's are always associated with CLOCK_REALTIME 2428 os::Linux::clock_gettime(CLOCK_REALTIME, &ts); 2429 // see unpackTime for discussion on overflow checking 2430 if (sec >= MAX_SECS) { 2431 ts.tv_sec += MAX_SECS; 2432 ts.tv_nsec = 0; 2433 } else { 2434 ts.tv_sec += sec; 2435 ts.tv_nsec += nsec; 2436 if (ts.tv_nsec >= NANOSECS_PER_SEC) { 2437 ts.tv_nsec -= NANOSECS_PER_SEC; 2438 ++ts.tv_sec; // note: this must be <= max_secs 2439 } 2440 } 2441 2442 while (1) { 2443 int result = sem_timedwait(&_semaphore, &ts); 2444 if (result == 0) { 2445 return true; 2446 } else if (errno == EINTR) { 2447 continue; 2448 } else if (errno == ETIMEDOUT) { 2449 return false; 2450 } else { 2451 return false; 2452 } 2453 } 2454 } 2455 2456 extern "C" { 2457 typedef void (*sa_handler_t)(int); 2458 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2459 } 2460 2461 void* os::signal(int signal_number, void* handler) { 2462 struct sigaction sigAct, oldSigAct; 2463 2464 sigfillset(&(sigAct.sa_mask)); 2465 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2466 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2467 2468 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2469 // -1 means registration failed 2470 return (void *)-1; 2471 } 2472 2473 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2474 } 2475 2476 void os::signal_raise(int signal_number) { 2477 ::raise(signal_number); 2478 } 2479 2480 // The following code is moved from os.cpp for making this 2481 // code platform specific, which it is by its very nature. 2482 2483 // Will be modified when max signal is changed to be dynamic 2484 int os::sigexitnum_pd() { 2485 return NSIG; 2486 } 2487 2488 // a counter for each possible signal value 2489 static volatile jint pending_signals[NSIG+1] = { 0 }; 2490 2491 // Linux(POSIX) specific hand shaking semaphore. 2492 static sem_t sig_sem; 2493 static Semaphore sr_semaphore; 2494 2495 void os::signal_init_pd() { 2496 // Initialize signal structures 2497 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2498 2499 // Initialize signal semaphore 2500 ::sem_init(&sig_sem, 0, 0); 2501 } 2502 2503 void os::signal_notify(int sig) { 2504 Atomic::inc(&pending_signals[sig]); 2505 ::sem_post(&sig_sem); 2506 } 2507 2508 static int check_pending_signals(bool wait) { 2509 Atomic::store(0, &sigint_count); 2510 for (;;) { 2511 for (int i = 0; i < NSIG + 1; i++) { 2512 jint n = pending_signals[i]; 2513 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2514 return i; 2515 } 2516 } 2517 if (!wait) { 2518 return -1; 2519 } 2520 JavaThread *thread = JavaThread::current(); 2521 ThreadBlockInVM tbivm(thread); 2522 2523 bool threadIsSuspended; 2524 do { 2525 thread->set_suspend_equivalent(); 2526 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2527 ::sem_wait(&sig_sem); 2528 2529 // were we externally suspended while we were waiting? 2530 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2531 if (threadIsSuspended) { 2532 // The semaphore has been incremented, but while we were waiting 2533 // another thread suspended us. We don't want to continue running 2534 // while suspended because that would surprise the thread that 2535 // suspended us. 2536 ::sem_post(&sig_sem); 2537 2538 thread->java_suspend_self(); 2539 } 2540 } while (threadIsSuspended); 2541 } 2542 } 2543 2544 int os::signal_lookup() { 2545 return check_pending_signals(false); 2546 } 2547 2548 int os::signal_wait() { 2549 return check_pending_signals(true); 2550 } 2551 2552 //////////////////////////////////////////////////////////////////////////////// 2553 // Virtual Memory 2554 2555 int os::vm_page_size() { 2556 // Seems redundant as all get out 2557 assert(os::Linux::page_size() != -1, "must call os::init"); 2558 return os::Linux::page_size(); 2559 } 2560 2561 // Solaris allocates memory by pages. 2562 int os::vm_allocation_granularity() { 2563 assert(os::Linux::page_size() != -1, "must call os::init"); 2564 return os::Linux::page_size(); 2565 } 2566 2567 // Rationale behind this function: 2568 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2569 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2570 // samples for JITted code. Here we create private executable mapping over the code cache 2571 // and then we can use standard (well, almost, as mapping can change) way to provide 2572 // info for the reporting script by storing timestamp and location of symbol 2573 void linux_wrap_code(char* base, size_t size) { 2574 static volatile jint cnt = 0; 2575 2576 if (!UseOprofile) { 2577 return; 2578 } 2579 2580 char buf[PATH_MAX+1]; 2581 int num = Atomic::add(1, &cnt); 2582 2583 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2584 os::get_temp_directory(), os::current_process_id(), num); 2585 unlink(buf); 2586 2587 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2588 2589 if (fd != -1) { 2590 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2591 if (rv != (off_t)-1) { 2592 if (::write(fd, "", 1) == 1) { 2593 mmap(base, size, 2594 PROT_READ|PROT_WRITE|PROT_EXEC, 2595 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2596 } 2597 } 2598 ::close(fd); 2599 unlink(buf); 2600 } 2601 } 2602 2603 static bool recoverable_mmap_error(int err) { 2604 // See if the error is one we can let the caller handle. This 2605 // list of errno values comes from JBS-6843484. I can't find a 2606 // Linux man page that documents this specific set of errno 2607 // values so while this list currently matches Solaris, it may 2608 // change as we gain experience with this failure mode. 2609 switch (err) { 2610 case EBADF: 2611 case EINVAL: 2612 case ENOTSUP: 2613 // let the caller deal with these errors 2614 return true; 2615 2616 default: 2617 // Any remaining errors on this OS can cause our reserved mapping 2618 // to be lost. That can cause confusion where different data 2619 // structures think they have the same memory mapped. The worst 2620 // scenario is if both the VM and a library think they have the 2621 // same memory mapped. 2622 return false; 2623 } 2624 } 2625 2626 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2627 int err) { 2628 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2629 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2630 strerror(err), err); 2631 } 2632 2633 static void warn_fail_commit_memory(char* addr, size_t size, 2634 size_t alignment_hint, bool exec, 2635 int err) { 2636 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2637 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2638 alignment_hint, exec, strerror(err), err); 2639 } 2640 2641 // NOTE: Linux kernel does not really reserve the pages for us. 2642 // All it does is to check if there are enough free pages 2643 // left at the time of mmap(). This could be a potential 2644 // problem. 2645 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2646 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2647 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2648 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2649 if (res != (uintptr_t) MAP_FAILED) { 2650 if (UseNUMAInterleaving) { 2651 numa_make_global(addr, size); 2652 } 2653 return 0; 2654 } 2655 2656 int err = errno; // save errno from mmap() call above 2657 2658 if (!recoverable_mmap_error(err)) { 2659 warn_fail_commit_memory(addr, size, exec, err); 2660 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2661 } 2662 2663 return err; 2664 } 2665 2666 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2667 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2668 } 2669 2670 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2671 const char* mesg) { 2672 assert(mesg != NULL, "mesg must be specified"); 2673 int err = os::Linux::commit_memory_impl(addr, size, exec); 2674 if (err != 0) { 2675 // the caller wants all commit errors to exit with the specified mesg: 2676 warn_fail_commit_memory(addr, size, exec, err); 2677 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2678 } 2679 } 2680 2681 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2682 #ifndef MAP_HUGETLB 2683 #define MAP_HUGETLB 0x40000 2684 #endif 2685 2686 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2687 #ifndef MADV_HUGEPAGE 2688 #define MADV_HUGEPAGE 14 2689 #endif 2690 2691 int os::Linux::commit_memory_impl(char* addr, size_t size, 2692 size_t alignment_hint, bool exec) { 2693 int err = os::Linux::commit_memory_impl(addr, size, exec); 2694 if (err == 0) { 2695 realign_memory(addr, size, alignment_hint); 2696 } 2697 return err; 2698 } 2699 2700 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2701 bool exec) { 2702 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2703 } 2704 2705 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2706 size_t alignment_hint, bool exec, 2707 const char* mesg) { 2708 assert(mesg != NULL, "mesg must be specified"); 2709 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2710 if (err != 0) { 2711 // the caller wants all commit errors to exit with the specified mesg: 2712 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2713 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2714 } 2715 } 2716 2717 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2718 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2719 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2720 // be supported or the memory may already be backed by huge pages. 2721 ::madvise(addr, bytes, MADV_HUGEPAGE); 2722 } 2723 } 2724 2725 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2726 // This method works by doing an mmap over an existing mmaping and effectively discarding 2727 // the existing pages. However it won't work for SHM-based large pages that cannot be 2728 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2729 // small pages on top of the SHM segment. This method always works for small pages, so we 2730 // allow that in any case. 2731 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2732 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2733 } 2734 } 2735 2736 void os::numa_make_global(char *addr, size_t bytes) { 2737 Linux::numa_interleave_memory(addr, bytes); 2738 } 2739 2740 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2741 // bind policy to MPOL_PREFERRED for the current thread. 2742 #define USE_MPOL_PREFERRED 0 2743 2744 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2745 // To make NUMA and large pages more robust when both enabled, we need to ease 2746 // the requirements on where the memory should be allocated. MPOL_BIND is the 2747 // default policy and it will force memory to be allocated on the specified 2748 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2749 // the specified node, but will not force it. Using this policy will prevent 2750 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2751 // free large pages. 2752 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2753 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2754 } 2755 2756 bool os::numa_topology_changed() { return false; } 2757 2758 size_t os::numa_get_groups_num() { 2759 int max_node = Linux::numa_max_node(); 2760 return max_node > 0 ? max_node + 1 : 1; 2761 } 2762 2763 int os::numa_get_group_id() { 2764 int cpu_id = Linux::sched_getcpu(); 2765 if (cpu_id != -1) { 2766 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2767 if (lgrp_id != -1) { 2768 return lgrp_id; 2769 } 2770 } 2771 return 0; 2772 } 2773 2774 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2775 for (size_t i = 0; i < size; i++) { 2776 ids[i] = i; 2777 } 2778 return size; 2779 } 2780 2781 bool os::get_page_info(char *start, page_info* info) { 2782 return false; 2783 } 2784 2785 char *os::scan_pages(char *start, char* end, page_info* page_expected, 2786 page_info* page_found) { 2787 return end; 2788 } 2789 2790 2791 int os::Linux::sched_getcpu_syscall(void) { 2792 unsigned int cpu; 2793 int retval = -1; 2794 2795 #if defined(IA32) 2796 #ifndef SYS_getcpu 2797 #define SYS_getcpu 318 2798 #endif 2799 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2800 #elif defined(AMD64) 2801 // Unfortunately we have to bring all these macros here from vsyscall.h 2802 // to be able to compile on old linuxes. 2803 #define __NR_vgetcpu 2 2804 #define VSYSCALL_START (-10UL << 20) 2805 #define VSYSCALL_SIZE 1024 2806 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2807 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2808 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2809 retval = vgetcpu(&cpu, NULL, NULL); 2810 #endif 2811 2812 return (retval == -1) ? retval : cpu; 2813 } 2814 2815 // Something to do with the numa-aware allocator needs these symbols 2816 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2817 extern "C" JNIEXPORT void numa_error(char *where) { } 2818 extern "C" JNIEXPORT int fork1() { return fork(); } 2819 2820 2821 // If we are running with libnuma version > 2, then we should 2822 // be trying to use symbols with versions 1.1 2823 // If we are running with earlier version, which did not have symbol versions, 2824 // we should use the base version. 2825 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2826 void *f = dlvsym(handle, name, "libnuma_1.1"); 2827 if (f == NULL) { 2828 f = dlsym(handle, name); 2829 } 2830 return f; 2831 } 2832 2833 bool os::Linux::libnuma_init() { 2834 // sched_getcpu() should be in libc. 2835 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2836 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2837 2838 // If it's not, try a direct syscall. 2839 if (sched_getcpu() == -1) { 2840 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2841 (void*)&sched_getcpu_syscall)); 2842 } 2843 2844 if (sched_getcpu() != -1) { // Does it work? 2845 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2846 if (handle != NULL) { 2847 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2848 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2849 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2850 libnuma_dlsym(handle, "numa_max_node"))); 2851 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2852 libnuma_dlsym(handle, "numa_available"))); 2853 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2854 libnuma_dlsym(handle, "numa_tonode_memory"))); 2855 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2856 libnuma_dlsym(handle, "numa_interleave_memory"))); 2857 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2858 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2859 2860 2861 if (numa_available() != -1) { 2862 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2863 // Create a cpu -> node mapping 2864 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2865 rebuild_cpu_to_node_map(); 2866 return true; 2867 } 2868 } 2869 } 2870 return false; 2871 } 2872 2873 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2874 // The table is later used in get_node_by_cpu(). 2875 void os::Linux::rebuild_cpu_to_node_map() { 2876 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2877 // in libnuma (possible values are starting from 16, 2878 // and continuing up with every other power of 2, but less 2879 // than the maximum number of CPUs supported by kernel), and 2880 // is a subject to change (in libnuma version 2 the requirements 2881 // are more reasonable) we'll just hardcode the number they use 2882 // in the library. 2883 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2884 2885 size_t cpu_num = os::active_processor_count(); 2886 size_t cpu_map_size = NCPUS / BitsPerCLong; 2887 size_t cpu_map_valid_size = 2888 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2889 2890 cpu_to_node()->clear(); 2891 cpu_to_node()->at_grow(cpu_num - 1); 2892 size_t node_num = numa_get_groups_num(); 2893 2894 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2895 for (size_t i = 0; i < node_num; i++) { 2896 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2897 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2898 if (cpu_map[j] != 0) { 2899 for (size_t k = 0; k < BitsPerCLong; k++) { 2900 if (cpu_map[j] & (1UL << k)) { 2901 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2902 } 2903 } 2904 } 2905 } 2906 } 2907 } 2908 FREE_C_HEAP_ARRAY(unsigned long, cpu_map); 2909 } 2910 2911 int os::Linux::get_node_by_cpu(int cpu_id) { 2912 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2913 return cpu_to_node()->at(cpu_id); 2914 } 2915 return -1; 2916 } 2917 2918 GrowableArray<int>* os::Linux::_cpu_to_node; 2919 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2920 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2921 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2922 os::Linux::numa_available_func_t os::Linux::_numa_available; 2923 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2924 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2925 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2926 unsigned long* os::Linux::_numa_all_nodes; 2927 2928 bool os::pd_uncommit_memory(char* addr, size_t size) { 2929 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2930 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2931 return res != (uintptr_t) MAP_FAILED; 2932 } 2933 2934 static address get_stack_commited_bottom(address bottom, size_t size) { 2935 address nbot = bottom; 2936 address ntop = bottom + size; 2937 2938 size_t page_sz = os::vm_page_size(); 2939 unsigned pages = size / page_sz; 2940 2941 unsigned char vec[1]; 2942 unsigned imin = 1, imax = pages + 1, imid; 2943 int mincore_return_value = 0; 2944 2945 assert(imin <= imax, "Unexpected page size"); 2946 2947 while (imin < imax) { 2948 imid = (imax + imin) / 2; 2949 nbot = ntop - (imid * page_sz); 2950 2951 // Use a trick with mincore to check whether the page is mapped or not. 2952 // mincore sets vec to 1 if page resides in memory and to 0 if page 2953 // is swapped output but if page we are asking for is unmapped 2954 // it returns -1,ENOMEM 2955 mincore_return_value = mincore(nbot, page_sz, vec); 2956 2957 if (mincore_return_value == -1) { 2958 // Page is not mapped go up 2959 // to find first mapped page 2960 if (errno != EAGAIN) { 2961 assert(errno == ENOMEM, "Unexpected mincore errno"); 2962 imax = imid; 2963 } 2964 } else { 2965 // Page is mapped go down 2966 // to find first not mapped page 2967 imin = imid + 1; 2968 } 2969 } 2970 2971 nbot = nbot + page_sz; 2972 2973 // Adjust stack bottom one page up if last checked page is not mapped 2974 if (mincore_return_value == -1) { 2975 nbot = nbot + page_sz; 2976 } 2977 2978 return nbot; 2979 } 2980 2981 2982 // Linux uses a growable mapping for the stack, and if the mapping for 2983 // the stack guard pages is not removed when we detach a thread the 2984 // stack cannot grow beyond the pages where the stack guard was 2985 // mapped. If at some point later in the process the stack expands to 2986 // that point, the Linux kernel cannot expand the stack any further 2987 // because the guard pages are in the way, and a segfault occurs. 2988 // 2989 // However, it's essential not to split the stack region by unmapping 2990 // a region (leaving a hole) that's already part of the stack mapping, 2991 // so if the stack mapping has already grown beyond the guard pages at 2992 // the time we create them, we have to truncate the stack mapping. 2993 // So, we need to know the extent of the stack mapping when 2994 // create_stack_guard_pages() is called. 2995 2996 // We only need this for stacks that are growable: at the time of 2997 // writing thread stacks don't use growable mappings (i.e. those 2998 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 2999 // only applies to the main thread. 3000 3001 // If the (growable) stack mapping already extends beyond the point 3002 // where we're going to put our guard pages, truncate the mapping at 3003 // that point by munmap()ping it. This ensures that when we later 3004 // munmap() the guard pages we don't leave a hole in the stack 3005 // mapping. This only affects the main/initial thread 3006 3007 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3008 if (os::Linux::is_initial_thread()) { 3009 // As we manually grow stack up to bottom inside create_attached_thread(), 3010 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3011 // we don't need to do anything special. 3012 // Check it first, before calling heavy function. 3013 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3014 unsigned char vec[1]; 3015 3016 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3017 // Fallback to slow path on all errors, including EAGAIN 3018 stack_extent = (uintptr_t) get_stack_commited_bottom( 3019 os::Linux::initial_thread_stack_bottom(), 3020 (size_t)addr - stack_extent); 3021 } 3022 3023 if (stack_extent < (uintptr_t)addr) { 3024 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3025 } 3026 } 3027 3028 return os::commit_memory(addr, size, !ExecMem); 3029 } 3030 3031 // If this is a growable mapping, remove the guard pages entirely by 3032 // munmap()ping them. If not, just call uncommit_memory(). This only 3033 // affects the main/initial thread, but guard against future OS changes 3034 // It's safe to always unmap guard pages for initial thread because we 3035 // always place it right after end of the mapped region 3036 3037 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3038 uintptr_t stack_extent, stack_base; 3039 3040 if (os::Linux::is_initial_thread()) { 3041 return ::munmap(addr, size) == 0; 3042 } 3043 3044 return os::uncommit_memory(addr, size); 3045 } 3046 3047 static address _highest_vm_reserved_address = NULL; 3048 3049 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3050 // at 'requested_addr'. If there are existing memory mappings at the same 3051 // location, however, they will be overwritten. If 'fixed' is false, 3052 // 'requested_addr' is only treated as a hint, the return value may or 3053 // may not start from the requested address. Unlike Linux mmap(), this 3054 // function returns NULL to indicate failure. 3055 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3056 char * addr; 3057 int flags; 3058 3059 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3060 if (fixed) { 3061 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3062 flags |= MAP_FIXED; 3063 } 3064 3065 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3066 // touch an uncommitted page. Otherwise, the read/write might 3067 // succeed if we have enough swap space to back the physical page. 3068 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3069 flags, -1, 0); 3070 3071 if (addr != MAP_FAILED) { 3072 // anon_mmap() should only get called during VM initialization, 3073 // don't need lock (actually we can skip locking even it can be called 3074 // from multiple threads, because _highest_vm_reserved_address is just a 3075 // hint about the upper limit of non-stack memory regions.) 3076 if ((address)addr + bytes > _highest_vm_reserved_address) { 3077 _highest_vm_reserved_address = (address)addr + bytes; 3078 } 3079 } 3080 3081 return addr == MAP_FAILED ? NULL : addr; 3082 } 3083 3084 // Don't update _highest_vm_reserved_address, because there might be memory 3085 // regions above addr + size. If so, releasing a memory region only creates 3086 // a hole in the address space, it doesn't help prevent heap-stack collision. 3087 // 3088 static int anon_munmap(char * addr, size_t size) { 3089 return ::munmap(addr, size) == 0; 3090 } 3091 3092 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3093 size_t alignment_hint) { 3094 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3095 } 3096 3097 bool os::pd_release_memory(char* addr, size_t size) { 3098 return anon_munmap(addr, size); 3099 } 3100 3101 static address highest_vm_reserved_address() { 3102 return _highest_vm_reserved_address; 3103 } 3104 3105 static bool linux_mprotect(char* addr, size_t size, int prot) { 3106 // Linux wants the mprotect address argument to be page aligned. 3107 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3108 3109 // According to SUSv3, mprotect() should only be used with mappings 3110 // established by mmap(), and mmap() always maps whole pages. Unaligned 3111 // 'addr' likely indicates problem in the VM (e.g. trying to change 3112 // protection of malloc'ed or statically allocated memory). Check the 3113 // caller if you hit this assert. 3114 assert(addr == bottom, "sanity check"); 3115 3116 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3117 return ::mprotect(bottom, size, prot) == 0; 3118 } 3119 3120 // Set protections specified 3121 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3122 bool is_committed) { 3123 unsigned int p = 0; 3124 switch (prot) { 3125 case MEM_PROT_NONE: p = PROT_NONE; break; 3126 case MEM_PROT_READ: p = PROT_READ; break; 3127 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3128 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3129 default: 3130 ShouldNotReachHere(); 3131 } 3132 // is_committed is unused. 3133 return linux_mprotect(addr, bytes, p); 3134 } 3135 3136 bool os::guard_memory(char* addr, size_t size) { 3137 return linux_mprotect(addr, size, PROT_NONE); 3138 } 3139 3140 bool os::unguard_memory(char* addr, size_t size) { 3141 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3142 } 3143 3144 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, 3145 size_t page_size) { 3146 bool result = false; 3147 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3148 MAP_ANONYMOUS|MAP_PRIVATE, 3149 -1, 0); 3150 if (p != MAP_FAILED) { 3151 void *aligned_p = align_ptr_up(p, page_size); 3152 3153 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3154 3155 munmap(p, page_size * 2); 3156 } 3157 3158 if (warn && !result) { 3159 warning("TransparentHugePages is not supported by the operating system."); 3160 } 3161 3162 return result; 3163 } 3164 3165 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3166 bool result = false; 3167 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3168 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3169 -1, 0); 3170 3171 if (p != MAP_FAILED) { 3172 // We don't know if this really is a huge page or not. 3173 FILE *fp = fopen("/proc/self/maps", "r"); 3174 if (fp) { 3175 while (!feof(fp)) { 3176 char chars[257]; 3177 long x = 0; 3178 if (fgets(chars, sizeof(chars), fp)) { 3179 if (sscanf(chars, "%lx-%*x", &x) == 1 3180 && x == (long)p) { 3181 if (strstr (chars, "hugepage")) { 3182 result = true; 3183 break; 3184 } 3185 } 3186 } 3187 } 3188 fclose(fp); 3189 } 3190 munmap(p, page_size); 3191 } 3192 3193 if (warn && !result) { 3194 warning("HugeTLBFS is not supported by the operating system."); 3195 } 3196 3197 return result; 3198 } 3199 3200 // Set the coredump_filter bits to include largepages in core dump (bit 6) 3201 // 3202 // From the coredump_filter documentation: 3203 // 3204 // - (bit 0) anonymous private memory 3205 // - (bit 1) anonymous shared memory 3206 // - (bit 2) file-backed private memory 3207 // - (bit 3) file-backed shared memory 3208 // - (bit 4) ELF header pages in file-backed private memory areas (it is 3209 // effective only if the bit 2 is cleared) 3210 // - (bit 5) hugetlb private memory 3211 // - (bit 6) hugetlb shared memory 3212 // 3213 static void set_coredump_filter(void) { 3214 FILE *f; 3215 long cdm; 3216 3217 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3218 return; 3219 } 3220 3221 if (fscanf(f, "%lx", &cdm) != 1) { 3222 fclose(f); 3223 return; 3224 } 3225 3226 rewind(f); 3227 3228 if ((cdm & LARGEPAGES_BIT) == 0) { 3229 cdm |= LARGEPAGES_BIT; 3230 fprintf(f, "%#lx", cdm); 3231 } 3232 3233 fclose(f); 3234 } 3235 3236 // Large page support 3237 3238 static size_t _large_page_size = 0; 3239 3240 size_t os::Linux::find_large_page_size() { 3241 size_t large_page_size = 0; 3242 3243 // large_page_size on Linux is used to round up heap size. x86 uses either 3244 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3245 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3246 // page as large as 256M. 3247 // 3248 // Here we try to figure out page size by parsing /proc/meminfo and looking 3249 // for a line with the following format: 3250 // Hugepagesize: 2048 kB 3251 // 3252 // If we can't determine the value (e.g. /proc is not mounted, or the text 3253 // format has been changed), we'll use the largest page size supported by 3254 // the processor. 3255 3256 #ifndef ZERO 3257 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3258 ARM32_ONLY(2 * M) PPC_ONLY(4 * M) AARCH64_ONLY(2 * M); 3259 #endif // ZERO 3260 3261 FILE *fp = fopen("/proc/meminfo", "r"); 3262 if (fp) { 3263 while (!feof(fp)) { 3264 int x = 0; 3265 char buf[16]; 3266 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3267 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3268 large_page_size = x * K; 3269 break; 3270 } 3271 } else { 3272 // skip to next line 3273 for (;;) { 3274 int ch = fgetc(fp); 3275 if (ch == EOF || ch == (int)'\n') break; 3276 } 3277 } 3278 } 3279 fclose(fp); 3280 } 3281 3282 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3283 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3284 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3285 proper_unit_for_byte_size(large_page_size)); 3286 } 3287 3288 return large_page_size; 3289 } 3290 3291 size_t os::Linux::setup_large_page_size() { 3292 _large_page_size = Linux::find_large_page_size(); 3293 const size_t default_page_size = (size_t)Linux::page_size(); 3294 if (_large_page_size > default_page_size) { 3295 _page_sizes[0] = _large_page_size; 3296 _page_sizes[1] = default_page_size; 3297 _page_sizes[2] = 0; 3298 } 3299 3300 return _large_page_size; 3301 } 3302 3303 bool os::Linux::setup_large_page_type(size_t page_size) { 3304 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3305 FLAG_IS_DEFAULT(UseSHM) && 3306 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3307 3308 // The type of large pages has not been specified by the user. 3309 3310 // Try UseHugeTLBFS and then UseSHM. 3311 UseHugeTLBFS = UseSHM = true; 3312 3313 // Don't try UseTransparentHugePages since there are known 3314 // performance issues with it turned on. This might change in the future. 3315 UseTransparentHugePages = false; 3316 } 3317 3318 if (UseTransparentHugePages) { 3319 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3320 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3321 UseHugeTLBFS = false; 3322 UseSHM = false; 3323 return true; 3324 } 3325 UseTransparentHugePages = false; 3326 } 3327 3328 if (UseHugeTLBFS) { 3329 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3330 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3331 UseSHM = false; 3332 return true; 3333 } 3334 UseHugeTLBFS = false; 3335 } 3336 3337 return UseSHM; 3338 } 3339 3340 void os::large_page_init() { 3341 if (!UseLargePages && 3342 !UseTransparentHugePages && 3343 !UseHugeTLBFS && 3344 !UseSHM) { 3345 // Not using large pages. 3346 return; 3347 } 3348 3349 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3350 // The user explicitly turned off large pages. 3351 // Ignore the rest of the large pages flags. 3352 UseTransparentHugePages = false; 3353 UseHugeTLBFS = false; 3354 UseSHM = false; 3355 return; 3356 } 3357 3358 size_t large_page_size = Linux::setup_large_page_size(); 3359 UseLargePages = Linux::setup_large_page_type(large_page_size); 3360 3361 set_coredump_filter(); 3362 } 3363 3364 #ifndef SHM_HUGETLB 3365 #define SHM_HUGETLB 04000 3366 #endif 3367 3368 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, 3369 char* req_addr, bool exec) { 3370 // "exec" is passed in but not used. Creating the shared image for 3371 // the code cache doesn't have an SHM_X executable permission to check. 3372 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3373 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3374 3375 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3376 return NULL; // Fallback to small pages. 3377 } 3378 3379 key_t key = IPC_PRIVATE; 3380 char *addr; 3381 3382 bool warn_on_failure = UseLargePages && 3383 (!FLAG_IS_DEFAULT(UseLargePages) || 3384 !FLAG_IS_DEFAULT(UseSHM) || 3385 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3386 char msg[128]; 3387 3388 // Create a large shared memory region to attach to based on size. 3389 // Currently, size is the total size of the heap 3390 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3391 if (shmid == -1) { 3392 // Possible reasons for shmget failure: 3393 // 1. shmmax is too small for Java heap. 3394 // > check shmmax value: cat /proc/sys/kernel/shmmax 3395 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3396 // 2. not enough large page memory. 3397 // > check available large pages: cat /proc/meminfo 3398 // > increase amount of large pages: 3399 // echo new_value > /proc/sys/vm/nr_hugepages 3400 // Note 1: different Linux may use different name for this property, 3401 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3402 // Note 2: it's possible there's enough physical memory available but 3403 // they are so fragmented after a long run that they can't 3404 // coalesce into large pages. Try to reserve large pages when 3405 // the system is still "fresh". 3406 if (warn_on_failure) { 3407 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3408 warning("%s", msg); 3409 } 3410 return NULL; 3411 } 3412 3413 // attach to the region 3414 addr = (char*)shmat(shmid, req_addr, 0); 3415 int err = errno; 3416 3417 // Remove shmid. If shmat() is successful, the actual shared memory segment 3418 // will be deleted when it's detached by shmdt() or when the process 3419 // terminates. If shmat() is not successful this will remove the shared 3420 // segment immediately. 3421 shmctl(shmid, IPC_RMID, NULL); 3422 3423 if ((intptr_t)addr == -1) { 3424 if (warn_on_failure) { 3425 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3426 warning("%s", msg); 3427 } 3428 return NULL; 3429 } 3430 3431 return addr; 3432 } 3433 3434 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, 3435 int error) { 3436 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3437 3438 bool warn_on_failure = UseLargePages && 3439 (!FLAG_IS_DEFAULT(UseLargePages) || 3440 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3441 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3442 3443 if (warn_on_failure) { 3444 char msg[128]; 3445 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3446 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3447 warning("%s", msg); 3448 } 3449 } 3450 3451 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, 3452 char* req_addr, 3453 bool exec) { 3454 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3455 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3456 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3457 3458 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3459 char* addr = (char*)::mmap(req_addr, bytes, prot, 3460 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3461 -1, 0); 3462 3463 if (addr == MAP_FAILED) { 3464 warn_on_large_pages_failure(req_addr, bytes, errno); 3465 return NULL; 3466 } 3467 3468 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3469 3470 return addr; 3471 } 3472 3473 // Helper for os::Linux::reserve_memory_special_huge_tlbfs_mixed(). 3474 // Allocate (using mmap, NO_RESERVE, with small pages) at either a given request address 3475 // (req_addr != NULL) or with a given alignment. 3476 // - bytes shall be a multiple of alignment. 3477 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment. 3478 // - alignment sets the alignment at which memory shall be allocated. 3479 // It must be a multiple of allocation granularity. 3480 // Returns address of memory or NULL. If req_addr was not NULL, will only return 3481 // req_addr or NULL. 3482 static char* anon_mmap_aligned(size_t bytes, size_t alignment, char* req_addr) { 3483 3484 size_t extra_size = bytes; 3485 if (req_addr == NULL && alignment > 0) { 3486 extra_size += alignment; 3487 } 3488 3489 char* start = (char*) ::mmap(req_addr, extra_size, PROT_NONE, 3490 MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, 3491 -1, 0); 3492 if (start == MAP_FAILED) { 3493 start = NULL; 3494 } else { 3495 if (req_addr != NULL) { 3496 if (start != req_addr) { 3497 ::munmap(start, extra_size); 3498 start = NULL; 3499 } 3500 } else { 3501 char* const start_aligned = (char*) align_ptr_up(start, alignment); 3502 char* const end_aligned = start_aligned + bytes; 3503 char* const end = start + extra_size; 3504 if (start_aligned > start) { 3505 ::munmap(start, start_aligned - start); 3506 } 3507 if (end_aligned < end) { 3508 ::munmap(end_aligned, end - end_aligned); 3509 } 3510 start = start_aligned; 3511 } 3512 } 3513 return start; 3514 3515 } 3516 3517 // Reserve memory using mmap(MAP_HUGETLB). 3518 // - bytes shall be a multiple of alignment. 3519 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment. 3520 // - alignment sets the alignment at which memory shall be allocated. 3521 // It must be a multiple of allocation granularity. 3522 // Returns address of memory or NULL. If req_addr was not NULL, will only return 3523 // req_addr or NULL. 3524 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, 3525 size_t alignment, 3526 char* req_addr, 3527 bool exec) { 3528 size_t large_page_size = os::large_page_size(); 3529 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3530 3531 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3532 assert(is_size_aligned(bytes, alignment), "Must be"); 3533 3534 // First reserve - but not commit - the address range in small pages. 3535 char* const start = anon_mmap_aligned(bytes, alignment, req_addr); 3536 3537 if (start == NULL) { 3538 return NULL; 3539 } 3540 3541 assert(is_ptr_aligned(start, alignment), "Must be"); 3542 3543 char* end = start + bytes; 3544 3545 // Find the regions of the allocated chunk that can be promoted to large pages. 3546 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3547 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3548 3549 size_t lp_bytes = lp_end - lp_start; 3550 3551 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3552 3553 if (lp_bytes == 0) { 3554 // The mapped region doesn't even span the start and the end of a large page. 3555 // Fall back to allocate a non-special area. 3556 ::munmap(start, end - start); 3557 return NULL; 3558 } 3559 3560 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3561 3562 void* result; 3563 3564 // Commit small-paged leading area. 3565 if (start != lp_start) { 3566 result = ::mmap(start, lp_start - start, prot, 3567 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3568 -1, 0); 3569 if (result == MAP_FAILED) { 3570 ::munmap(lp_start, end - lp_start); 3571 return NULL; 3572 } 3573 } 3574 3575 // Commit large-paged area. 3576 result = ::mmap(lp_start, lp_bytes, prot, 3577 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3578 -1, 0); 3579 if (result == MAP_FAILED) { 3580 warn_on_large_pages_failure(lp_start, lp_bytes, errno); 3581 // If the mmap above fails, the large pages region will be unmapped and we 3582 // have regions before and after with small pages. Release these regions. 3583 // 3584 // | mapped | unmapped | mapped | 3585 // ^ ^ ^ ^ 3586 // start lp_start lp_end end 3587 // 3588 ::munmap(start, lp_start - start); 3589 ::munmap(lp_end, end - lp_end); 3590 return NULL; 3591 } 3592 3593 // Commit small-paged trailing area. 3594 if (lp_end != end) { 3595 result = ::mmap(lp_end, end - lp_end, prot, 3596 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3597 -1, 0); 3598 if (result == MAP_FAILED) { 3599 ::munmap(start, lp_end - start); 3600 return NULL; 3601 } 3602 } 3603 3604 return start; 3605 } 3606 3607 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, 3608 size_t alignment, 3609 char* req_addr, 3610 bool exec) { 3611 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3612 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3613 assert(is_size_aligned(alignment, os::vm_allocation_granularity()), "Must be"); 3614 assert(is_power_of_2(os::large_page_size()), "Must be"); 3615 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3616 3617 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3618 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3619 } else { 3620 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3621 } 3622 } 3623 3624 char* os::reserve_memory_special(size_t bytes, size_t alignment, 3625 char* req_addr, bool exec) { 3626 assert(UseLargePages, "only for large pages"); 3627 3628 char* addr; 3629 if (UseSHM) { 3630 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3631 } else { 3632 assert(UseHugeTLBFS, "must be"); 3633 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3634 } 3635 3636 if (addr != NULL) { 3637 if (UseNUMAInterleaving) { 3638 numa_make_global(addr, bytes); 3639 } 3640 3641 // The memory is committed 3642 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC); 3643 } 3644 3645 return addr; 3646 } 3647 3648 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3649 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3650 return shmdt(base) == 0; 3651 } 3652 3653 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3654 return pd_release_memory(base, bytes); 3655 } 3656 3657 bool os::release_memory_special(char* base, size_t bytes) { 3658 bool res; 3659 if (MemTracker::tracking_level() > NMT_minimal) { 3660 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3661 res = os::Linux::release_memory_special_impl(base, bytes); 3662 if (res) { 3663 tkr.record((address)base, bytes); 3664 } 3665 3666 } else { 3667 res = os::Linux::release_memory_special_impl(base, bytes); 3668 } 3669 return res; 3670 } 3671 3672 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) { 3673 assert(UseLargePages, "only for large pages"); 3674 bool res; 3675 3676 if (UseSHM) { 3677 res = os::Linux::release_memory_special_shm(base, bytes); 3678 } else { 3679 assert(UseHugeTLBFS, "must be"); 3680 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3681 } 3682 return res; 3683 } 3684 3685 size_t os::large_page_size() { 3686 return _large_page_size; 3687 } 3688 3689 // With SysV SHM the entire memory region must be allocated as shared 3690 // memory. 3691 // HugeTLBFS allows application to commit large page memory on demand. 3692 // However, when committing memory with HugeTLBFS fails, the region 3693 // that was supposed to be committed will lose the old reservation 3694 // and allow other threads to steal that memory region. Because of this 3695 // behavior we can't commit HugeTLBFS memory. 3696 bool os::can_commit_large_page_memory() { 3697 return UseTransparentHugePages; 3698 } 3699 3700 bool os::can_execute_large_page_memory() { 3701 return UseTransparentHugePages || UseHugeTLBFS; 3702 } 3703 3704 // Reserve memory at an arbitrary address, only if that area is 3705 // available (and not reserved for something else). 3706 3707 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3708 const int max_tries = 10; 3709 char* base[max_tries]; 3710 size_t size[max_tries]; 3711 const size_t gap = 0x000000; 3712 3713 // Assert only that the size is a multiple of the page size, since 3714 // that's all that mmap requires, and since that's all we really know 3715 // about at this low abstraction level. If we need higher alignment, 3716 // we can either pass an alignment to this method or verify alignment 3717 // in one of the methods further up the call chain. See bug 5044738. 3718 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3719 3720 // Repeatedly allocate blocks until the block is allocated at the 3721 // right spot. Give up after max_tries. Note that reserve_memory() will 3722 // automatically update _highest_vm_reserved_address if the call is 3723 // successful. The variable tracks the highest memory address every reserved 3724 // by JVM. It is used to detect heap-stack collision if running with 3725 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3726 // space than needed, it could confuse the collision detecting code. To 3727 // solve the problem, save current _highest_vm_reserved_address and 3728 // calculate the correct value before return. 3729 address old_highest = _highest_vm_reserved_address; 3730 3731 // Linux mmap allows caller to pass an address as hint; give it a try first, 3732 // if kernel honors the hint then we can return immediately. 3733 char * addr = anon_mmap(requested_addr, bytes, false); 3734 if (addr == requested_addr) { 3735 return requested_addr; 3736 } 3737 3738 if (addr != NULL) { 3739 // mmap() is successful but it fails to reserve at the requested address 3740 anon_munmap(addr, bytes); 3741 } 3742 3743 int i; 3744 for (i = 0; i < max_tries; ++i) { 3745 base[i] = reserve_memory(bytes); 3746 3747 if (base[i] != NULL) { 3748 // Is this the block we wanted? 3749 if (base[i] == requested_addr) { 3750 size[i] = bytes; 3751 break; 3752 } 3753 3754 // Does this overlap the block we wanted? Give back the overlapped 3755 // parts and try again. 3756 3757 ptrdiff_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3758 if (top_overlap >= 0 && (size_t)top_overlap < bytes) { 3759 unmap_memory(base[i], top_overlap); 3760 base[i] += top_overlap; 3761 size[i] = bytes - top_overlap; 3762 } else { 3763 ptrdiff_t bottom_overlap = base[i] + bytes - requested_addr; 3764 if (bottom_overlap >= 0 && (size_t)bottom_overlap < bytes) { 3765 unmap_memory(requested_addr, bottom_overlap); 3766 size[i] = bytes - bottom_overlap; 3767 } else { 3768 size[i] = bytes; 3769 } 3770 } 3771 } 3772 } 3773 3774 // Give back the unused reserved pieces. 3775 3776 for (int j = 0; j < i; ++j) { 3777 if (base[j] != NULL) { 3778 unmap_memory(base[j], size[j]); 3779 } 3780 } 3781 3782 if (i < max_tries) { 3783 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3784 return requested_addr; 3785 } else { 3786 _highest_vm_reserved_address = old_highest; 3787 return NULL; 3788 } 3789 } 3790 3791 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3792 return ::read(fd, buf, nBytes); 3793 } 3794 3795 size_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) { 3796 return ::pread(fd, buf, nBytes, offset); 3797 } 3798 3799 // Short sleep, direct OS call. 3800 // 3801 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee 3802 // sched_yield(2) will actually give up the CPU: 3803 // 3804 // * Alone on this pariticular CPU, keeps running. 3805 // * Before the introduction of "skip_buddy" with "compat_yield" disabled 3806 // (pre 2.6.39). 3807 // 3808 // So calling this with 0 is an alternative. 3809 // 3810 void os::naked_short_sleep(jlong ms) { 3811 struct timespec req; 3812 3813 assert(ms < 1000, "Un-interruptable sleep, short time use only"); 3814 req.tv_sec = 0; 3815 if (ms > 0) { 3816 req.tv_nsec = (ms % 1000) * 1000000; 3817 } else { 3818 req.tv_nsec = 1; 3819 } 3820 3821 nanosleep(&req, NULL); 3822 3823 return; 3824 } 3825 3826 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3827 void os::infinite_sleep() { 3828 while (true) { // sleep forever ... 3829 ::sleep(100); // ... 100 seconds at a time 3830 } 3831 } 3832 3833 // Used to convert frequent JVM_Yield() to nops 3834 bool os::dont_yield() { 3835 return DontYieldALot; 3836 } 3837 3838 void os::naked_yield() { 3839 sched_yield(); 3840 } 3841 3842 //////////////////////////////////////////////////////////////////////////////// 3843 // thread priority support 3844 3845 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3846 // only supports dynamic priority, static priority must be zero. For real-time 3847 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3848 // However, for large multi-threaded applications, SCHED_RR is not only slower 3849 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3850 // of 5 runs - Sep 2005). 3851 // 3852 // The following code actually changes the niceness of kernel-thread/LWP. It 3853 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3854 // not the entire user process, and user level threads are 1:1 mapped to kernel 3855 // threads. It has always been the case, but could change in the future. For 3856 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3857 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3858 3859 int os::java_to_os_priority[CriticalPriority + 1] = { 3860 19, // 0 Entry should never be used 3861 3862 4, // 1 MinPriority 3863 3, // 2 3864 2, // 3 3865 3866 1, // 4 3867 0, // 5 NormPriority 3868 -1, // 6 3869 3870 -2, // 7 3871 -3, // 8 3872 -4, // 9 NearMaxPriority 3873 3874 -5, // 10 MaxPriority 3875 3876 -5 // 11 CriticalPriority 3877 }; 3878 3879 static int prio_init() { 3880 if (ThreadPriorityPolicy == 1) { 3881 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3882 // if effective uid is not root. Perhaps, a more elegant way of doing 3883 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3884 if (geteuid() != 0) { 3885 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3886 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3887 } 3888 ThreadPriorityPolicy = 0; 3889 } 3890 } 3891 if (UseCriticalJavaThreadPriority) { 3892 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3893 } 3894 return 0; 3895 } 3896 3897 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3898 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK; 3899 3900 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3901 return (ret == 0) ? OS_OK : OS_ERR; 3902 } 3903 3904 OSReturn os::get_native_priority(const Thread* const thread, 3905 int *priority_ptr) { 3906 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) { 3907 *priority_ptr = java_to_os_priority[NormPriority]; 3908 return OS_OK; 3909 } 3910 3911 errno = 0; 3912 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3913 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3914 } 3915 3916 // Hint to the underlying OS that a task switch would not be good. 3917 // Void return because it's a hint and can fail. 3918 void os::hint_no_preempt() {} 3919 3920 //////////////////////////////////////////////////////////////////////////////// 3921 // suspend/resume support 3922 3923 // the low-level signal-based suspend/resume support is a remnant from the 3924 // old VM-suspension that used to be for java-suspension, safepoints etc, 3925 // within hotspot. Now there is a single use-case for this: 3926 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3927 // that runs in the watcher thread. 3928 // The remaining code is greatly simplified from the more general suspension 3929 // code that used to be used. 3930 // 3931 // The protocol is quite simple: 3932 // - suspend: 3933 // - sends a signal to the target thread 3934 // - polls the suspend state of the osthread using a yield loop 3935 // - target thread signal handler (SR_handler) sets suspend state 3936 // and blocks in sigsuspend until continued 3937 // - resume: 3938 // - sets target osthread state to continue 3939 // - sends signal to end the sigsuspend loop in the SR_handler 3940 // 3941 // Note that the SR_lock plays no role in this suspend/resume protocol. 3942 3943 static void resume_clear_context(OSThread *osthread) { 3944 osthread->set_ucontext(NULL); 3945 osthread->set_siginfo(NULL); 3946 } 3947 3948 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, 3949 ucontext_t* context) { 3950 osthread->set_ucontext(context); 3951 osthread->set_siginfo(siginfo); 3952 } 3953 3954 // Handler function invoked when a thread's execution is suspended or 3955 // resumed. We have to be careful that only async-safe functions are 3956 // called here (Note: most pthread functions are not async safe and 3957 // should be avoided.) 3958 // 3959 // Note: sigwait() is a more natural fit than sigsuspend() from an 3960 // interface point of view, but sigwait() prevents the signal hander 3961 // from being run. libpthread would get very confused by not having 3962 // its signal handlers run and prevents sigwait()'s use with the 3963 // mutex granting granting signal. 3964 // 3965 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 3966 // 3967 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3968 // Save and restore errno to avoid confusing native code with EINTR 3969 // after sigsuspend. 3970 int old_errno = errno; 3971 3972 Thread* thread = Thread::current(); 3973 OSThread* osthread = thread->osthread(); 3974 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 3975 3976 os::SuspendResume::State current = osthread->sr.state(); 3977 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 3978 suspend_save_context(osthread, siginfo, context); 3979 3980 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 3981 os::SuspendResume::State state = osthread->sr.suspended(); 3982 if (state == os::SuspendResume::SR_SUSPENDED) { 3983 sigset_t suspend_set; // signals for sigsuspend() 3984 3985 // get current set of blocked signals and unblock resume signal 3986 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3987 sigdelset(&suspend_set, SR_signum); 3988 3989 sr_semaphore.signal(); 3990 // wait here until we are resumed 3991 while (1) { 3992 sigsuspend(&suspend_set); 3993 3994 os::SuspendResume::State result = osthread->sr.running(); 3995 if (result == os::SuspendResume::SR_RUNNING) { 3996 sr_semaphore.signal(); 3997 break; 3998 } 3999 } 4000 4001 } else if (state == os::SuspendResume::SR_RUNNING) { 4002 // request was cancelled, continue 4003 } else { 4004 ShouldNotReachHere(); 4005 } 4006 4007 resume_clear_context(osthread); 4008 } else if (current == os::SuspendResume::SR_RUNNING) { 4009 // request was cancelled, continue 4010 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 4011 // ignore 4012 } else { 4013 // ignore 4014 } 4015 4016 errno = old_errno; 4017 } 4018 4019 4020 static int SR_initialize() { 4021 struct sigaction act; 4022 char *s; 4023 // Get signal number to use for suspend/resume 4024 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 4025 int sig = ::strtol(s, 0, 10); 4026 if (sig > 0 || sig < _NSIG) { 4027 SR_signum = sig; 4028 } 4029 } 4030 4031 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 4032 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 4033 4034 sigemptyset(&SR_sigset); 4035 sigaddset(&SR_sigset, SR_signum); 4036 4037 // Set up signal handler for suspend/resume 4038 act.sa_flags = SA_RESTART|SA_SIGINFO; 4039 act.sa_handler = (void (*)(int)) SR_handler; 4040 4041 // SR_signum is blocked by default. 4042 // 4528190 - We also need to block pthread restart signal (32 on all 4043 // supported Linux platforms). Note that LinuxThreads need to block 4044 // this signal for all threads to work properly. So we don't have 4045 // to use hard-coded signal number when setting up the mask. 4046 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4047 4048 if (sigaction(SR_signum, &act, 0) == -1) { 4049 return -1; 4050 } 4051 4052 // Save signal flag 4053 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4054 return 0; 4055 } 4056 4057 static int sr_notify(OSThread* osthread) { 4058 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4059 assert_status(status == 0, status, "pthread_kill"); 4060 return status; 4061 } 4062 4063 // "Randomly" selected value for how long we want to spin 4064 // before bailing out on suspending a thread, also how often 4065 // we send a signal to a thread we want to resume 4066 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4067 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4068 4069 // returns true on success and false on error - really an error is fatal 4070 // but this seems the normal response to library errors 4071 static bool do_suspend(OSThread* osthread) { 4072 assert(osthread->sr.is_running(), "thread should be running"); 4073 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4074 4075 // mark as suspended and send signal 4076 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4077 // failed to switch, state wasn't running? 4078 ShouldNotReachHere(); 4079 return false; 4080 } 4081 4082 if (sr_notify(osthread) != 0) { 4083 ShouldNotReachHere(); 4084 } 4085 4086 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4087 while (true) { 4088 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4089 break; 4090 } else { 4091 // timeout 4092 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4093 if (cancelled == os::SuspendResume::SR_RUNNING) { 4094 return false; 4095 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4096 // make sure that we consume the signal on the semaphore as well 4097 sr_semaphore.wait(); 4098 break; 4099 } else { 4100 ShouldNotReachHere(); 4101 return false; 4102 } 4103 } 4104 } 4105 4106 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4107 return true; 4108 } 4109 4110 static void do_resume(OSThread* osthread) { 4111 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4112 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4113 4114 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4115 // failed to switch to WAKEUP_REQUEST 4116 ShouldNotReachHere(); 4117 return; 4118 } 4119 4120 while (true) { 4121 if (sr_notify(osthread) == 0) { 4122 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4123 if (osthread->sr.is_running()) { 4124 return; 4125 } 4126 } 4127 } else { 4128 ShouldNotReachHere(); 4129 } 4130 } 4131 4132 guarantee(osthread->sr.is_running(), "Must be running!"); 4133 } 4134 4135 /////////////////////////////////////////////////////////////////////////////////// 4136 // signal handling (except suspend/resume) 4137 4138 // This routine may be used by user applications as a "hook" to catch signals. 4139 // The user-defined signal handler must pass unrecognized signals to this 4140 // routine, and if it returns true (non-zero), then the signal handler must 4141 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4142 // routine will never retun false (zero), but instead will execute a VM panic 4143 // routine kill the process. 4144 // 4145 // If this routine returns false, it is OK to call it again. This allows 4146 // the user-defined signal handler to perform checks either before or after 4147 // the VM performs its own checks. Naturally, the user code would be making 4148 // a serious error if it tried to handle an exception (such as a null check 4149 // or breakpoint) that the VM was generating for its own correct operation. 4150 // 4151 // This routine may recognize any of the following kinds of signals: 4152 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4153 // It should be consulted by handlers for any of those signals. 4154 // 4155 // The caller of this routine must pass in the three arguments supplied 4156 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4157 // field of the structure passed to sigaction(). This routine assumes that 4158 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4159 // 4160 // Note that the VM will print warnings if it detects conflicting signal 4161 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4162 // 4163 extern "C" JNIEXPORT int JVM_handle_linux_signal(int signo, 4164 siginfo_t* siginfo, 4165 void* ucontext, 4166 int abort_if_unrecognized); 4167 4168 void signalHandler(int sig, siginfo_t* info, void* uc) { 4169 assert(info != NULL && uc != NULL, "it must be old kernel"); 4170 int orig_errno = errno; // Preserve errno value over signal handler. 4171 JVM_handle_linux_signal(sig, info, uc, true); 4172 errno = orig_errno; 4173 } 4174 4175 4176 // This boolean allows users to forward their own non-matching signals 4177 // to JVM_handle_linux_signal, harmlessly. 4178 bool os::Linux::signal_handlers_are_installed = false; 4179 4180 // For signal-chaining 4181 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4182 unsigned int os::Linux::sigs = 0; 4183 bool os::Linux::libjsig_is_loaded = false; 4184 typedef struct sigaction *(*get_signal_t)(int); 4185 get_signal_t os::Linux::get_signal_action = NULL; 4186 4187 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4188 struct sigaction *actp = NULL; 4189 4190 if (libjsig_is_loaded) { 4191 // Retrieve the old signal handler from libjsig 4192 actp = (*get_signal_action)(sig); 4193 } 4194 if (actp == NULL) { 4195 // Retrieve the preinstalled signal handler from jvm 4196 actp = get_preinstalled_handler(sig); 4197 } 4198 4199 return actp; 4200 } 4201 4202 static bool call_chained_handler(struct sigaction *actp, int sig, 4203 siginfo_t *siginfo, void *context) { 4204 // Call the old signal handler 4205 if (actp->sa_handler == SIG_DFL) { 4206 // It's more reasonable to let jvm treat it as an unexpected exception 4207 // instead of taking the default action. 4208 return false; 4209 } else if (actp->sa_handler != SIG_IGN) { 4210 if ((actp->sa_flags & SA_NODEFER) == 0) { 4211 // automaticlly block the signal 4212 sigaddset(&(actp->sa_mask), sig); 4213 } 4214 4215 sa_handler_t hand; 4216 sa_sigaction_t sa; 4217 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4218 // retrieve the chained handler 4219 if (siginfo_flag_set) { 4220 sa = actp->sa_sigaction; 4221 } else { 4222 hand = actp->sa_handler; 4223 } 4224 4225 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4226 actp->sa_handler = SIG_DFL; 4227 } 4228 4229 // try to honor the signal mask 4230 sigset_t oset; 4231 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4232 4233 // call into the chained handler 4234 if (siginfo_flag_set) { 4235 (*sa)(sig, siginfo, context); 4236 } else { 4237 (*hand)(sig); 4238 } 4239 4240 // restore the signal mask 4241 pthread_sigmask(SIG_SETMASK, &oset, 0); 4242 } 4243 // Tell jvm's signal handler the signal is taken care of. 4244 return true; 4245 } 4246 4247 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4248 bool chained = false; 4249 // signal-chaining 4250 if (UseSignalChaining) { 4251 struct sigaction *actp = get_chained_signal_action(sig); 4252 if (actp != NULL) { 4253 chained = call_chained_handler(actp, sig, siginfo, context); 4254 } 4255 } 4256 return chained; 4257 } 4258 4259 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4260 if ((((unsigned int)1 << sig) & sigs) != 0) { 4261 return &sigact[sig]; 4262 } 4263 return NULL; 4264 } 4265 4266 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4267 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4268 sigact[sig] = oldAct; 4269 sigs |= (unsigned int)1 << sig; 4270 } 4271 4272 // for diagnostic 4273 int os::Linux::sigflags[MAXSIGNUM]; 4274 4275 int os::Linux::get_our_sigflags(int sig) { 4276 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4277 return sigflags[sig]; 4278 } 4279 4280 void os::Linux::set_our_sigflags(int sig, int flags) { 4281 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4282 sigflags[sig] = flags; 4283 } 4284 4285 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4286 // Check for overwrite. 4287 struct sigaction oldAct; 4288 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4289 4290 void* oldhand = oldAct.sa_sigaction 4291 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4292 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4293 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4294 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4295 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4296 if (AllowUserSignalHandlers || !set_installed) { 4297 // Do not overwrite; user takes responsibility to forward to us. 4298 return; 4299 } else if (UseSignalChaining) { 4300 // save the old handler in jvm 4301 save_preinstalled_handler(sig, oldAct); 4302 // libjsig also interposes the sigaction() call below and saves the 4303 // old sigaction on it own. 4304 } else { 4305 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4306 "%#lx for signal %d.", (long)oldhand, sig)); 4307 } 4308 } 4309 4310 struct sigaction sigAct; 4311 sigfillset(&(sigAct.sa_mask)); 4312 sigAct.sa_handler = SIG_DFL; 4313 if (!set_installed) { 4314 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4315 } else { 4316 sigAct.sa_sigaction = signalHandler; 4317 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4318 } 4319 // Save flags, which are set by ours 4320 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4321 sigflags[sig] = sigAct.sa_flags; 4322 4323 int ret = sigaction(sig, &sigAct, &oldAct); 4324 assert(ret == 0, "check"); 4325 4326 void* oldhand2 = oldAct.sa_sigaction 4327 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4328 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4329 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4330 } 4331 4332 // install signal handlers for signals that HotSpot needs to 4333 // handle in order to support Java-level exception handling. 4334 4335 void os::Linux::install_signal_handlers() { 4336 if (!signal_handlers_are_installed) { 4337 signal_handlers_are_installed = true; 4338 4339 // signal-chaining 4340 typedef void (*signal_setting_t)(); 4341 signal_setting_t begin_signal_setting = NULL; 4342 signal_setting_t end_signal_setting = NULL; 4343 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4344 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4345 if (begin_signal_setting != NULL) { 4346 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4347 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4348 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4349 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4350 libjsig_is_loaded = true; 4351 assert(UseSignalChaining, "should enable signal-chaining"); 4352 } 4353 if (libjsig_is_loaded) { 4354 // Tell libjsig jvm is setting signal handlers 4355 (*begin_signal_setting)(); 4356 } 4357 4358 set_signal_handler(SIGSEGV, true); 4359 set_signal_handler(SIGPIPE, true); 4360 set_signal_handler(SIGBUS, true); 4361 set_signal_handler(SIGILL, true); 4362 set_signal_handler(SIGFPE, true); 4363 #if defined(PPC64) 4364 set_signal_handler(SIGTRAP, true); 4365 #endif 4366 set_signal_handler(SIGXFSZ, true); 4367 4368 if (libjsig_is_loaded) { 4369 // Tell libjsig jvm finishes setting signal handlers 4370 (*end_signal_setting)(); 4371 } 4372 4373 // We don't activate signal checker if libjsig is in place, we trust ourselves 4374 // and if UserSignalHandler is installed all bets are off. 4375 // Log that signal checking is off only if -verbose:jni is specified. 4376 if (CheckJNICalls) { 4377 if (libjsig_is_loaded) { 4378 if (PrintJNIResolving) { 4379 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4380 } 4381 check_signals = false; 4382 } 4383 if (AllowUserSignalHandlers) { 4384 if (PrintJNIResolving) { 4385 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4386 } 4387 check_signals = false; 4388 } 4389 } 4390 } 4391 } 4392 4393 // This is the fastest way to get thread cpu time on Linux. 4394 // Returns cpu time (user+sys) for any thread, not only for current. 4395 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4396 // It might work on 2.6.10+ with a special kernel/glibc patch. 4397 // For reference, please, see IEEE Std 1003.1-2004: 4398 // http://www.unix.org/single_unix_specification 4399 4400 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4401 struct timespec tp; 4402 int rc = os::Linux::clock_gettime(clockid, &tp); 4403 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4404 4405 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4406 } 4407 4408 ///// 4409 // glibc on Linux platform uses non-documented flag 4410 // to indicate, that some special sort of signal 4411 // trampoline is used. 4412 // We will never set this flag, and we should 4413 // ignore this flag in our diagnostic 4414 #ifdef SIGNIFICANT_SIGNAL_MASK 4415 #undef SIGNIFICANT_SIGNAL_MASK 4416 #endif 4417 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4418 4419 static const char* get_signal_handler_name(address handler, 4420 char* buf, int buflen) { 4421 int offset; 4422 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4423 if (found) { 4424 // skip directory names 4425 const char *p1, *p2; 4426 p1 = buf; 4427 size_t len = strlen(os::file_separator()); 4428 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4429 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4430 } else { 4431 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4432 } 4433 return buf; 4434 } 4435 4436 static void print_signal_handler(outputStream* st, int sig, 4437 char* buf, size_t buflen) { 4438 struct sigaction sa; 4439 4440 sigaction(sig, NULL, &sa); 4441 4442 // See comment for SIGNIFICANT_SIGNAL_MASK define 4443 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4444 4445 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4446 4447 address handler = (sa.sa_flags & SA_SIGINFO) 4448 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4449 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4450 4451 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4452 st->print("SIG_DFL"); 4453 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4454 st->print("SIG_IGN"); 4455 } else { 4456 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4457 } 4458 4459 st->print(", sa_mask[0]="); 4460 os::Posix::print_signal_set_short(st, &sa.sa_mask); 4461 4462 address rh = VMError::get_resetted_sighandler(sig); 4463 // May be, handler was resetted by VMError? 4464 if (rh != NULL) { 4465 handler = rh; 4466 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4467 } 4468 4469 st->print(", sa_flags="); 4470 os::Posix::print_sa_flags(st, sa.sa_flags); 4471 4472 // Check: is it our handler? 4473 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4474 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4475 // It is our signal handler 4476 // check for flags, reset system-used one! 4477 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4478 st->print( 4479 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4480 os::Linux::get_our_sigflags(sig)); 4481 } 4482 } 4483 st->cr(); 4484 } 4485 4486 4487 #define DO_SIGNAL_CHECK(sig) \ 4488 do { \ 4489 if (!sigismember(&check_signal_done, sig)) { \ 4490 os::Linux::check_signal_handler(sig); \ 4491 } \ 4492 } while (0) 4493 4494 // This method is a periodic task to check for misbehaving JNI applications 4495 // under CheckJNI, we can add any periodic checks here 4496 4497 void os::run_periodic_checks() { 4498 if (check_signals == false) return; 4499 4500 // SEGV and BUS if overridden could potentially prevent 4501 // generation of hs*.log in the event of a crash, debugging 4502 // such a case can be very challenging, so we absolutely 4503 // check the following for a good measure: 4504 DO_SIGNAL_CHECK(SIGSEGV); 4505 DO_SIGNAL_CHECK(SIGILL); 4506 DO_SIGNAL_CHECK(SIGFPE); 4507 DO_SIGNAL_CHECK(SIGBUS); 4508 DO_SIGNAL_CHECK(SIGPIPE); 4509 DO_SIGNAL_CHECK(SIGXFSZ); 4510 #if defined(PPC64) 4511 DO_SIGNAL_CHECK(SIGTRAP); 4512 #endif 4513 4514 // ReduceSignalUsage allows the user to override these handlers 4515 // see comments at the very top and jvm_solaris.h 4516 if (!ReduceSignalUsage) { 4517 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4518 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4519 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4520 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4521 } 4522 4523 DO_SIGNAL_CHECK(SR_signum); 4524 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4525 } 4526 4527 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4528 4529 static os_sigaction_t os_sigaction = NULL; 4530 4531 void os::Linux::check_signal_handler(int sig) { 4532 char buf[O_BUFLEN]; 4533 address jvmHandler = NULL; 4534 4535 4536 struct sigaction act; 4537 if (os_sigaction == NULL) { 4538 // only trust the default sigaction, in case it has been interposed 4539 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4540 if (os_sigaction == NULL) return; 4541 } 4542 4543 os_sigaction(sig, (struct sigaction*)NULL, &act); 4544 4545 4546 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4547 4548 address thisHandler = (act.sa_flags & SA_SIGINFO) 4549 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4550 : CAST_FROM_FN_PTR(address, act.sa_handler); 4551 4552 4553 switch (sig) { 4554 case SIGSEGV: 4555 case SIGBUS: 4556 case SIGFPE: 4557 case SIGPIPE: 4558 case SIGILL: 4559 case SIGXFSZ: 4560 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4561 break; 4562 4563 case SHUTDOWN1_SIGNAL: 4564 case SHUTDOWN2_SIGNAL: 4565 case SHUTDOWN3_SIGNAL: 4566 case BREAK_SIGNAL: 4567 jvmHandler = (address)user_handler(); 4568 break; 4569 4570 case INTERRUPT_SIGNAL: 4571 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4572 break; 4573 4574 default: 4575 if (sig == SR_signum) { 4576 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4577 } else { 4578 return; 4579 } 4580 break; 4581 } 4582 4583 if (thisHandler != jvmHandler) { 4584 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4585 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4586 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4587 // No need to check this sig any longer 4588 sigaddset(&check_signal_done, sig); 4589 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN 4590 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) { 4591 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell", 4592 exception_name(sig, buf, O_BUFLEN)); 4593 } 4594 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4595 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4596 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4597 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4598 // No need to check this sig any longer 4599 sigaddset(&check_signal_done, sig); 4600 } 4601 4602 // Dump all the signal 4603 if (sigismember(&check_signal_done, sig)) { 4604 print_signal_handlers(tty, buf, O_BUFLEN); 4605 } 4606 } 4607 4608 extern void report_error(char* file_name, int line_no, char* title, 4609 char* format, ...); 4610 4611 extern bool signal_name(int signo, char* buf, size_t len); 4612 4613 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4614 if (0 < exception_code && exception_code <= SIGRTMAX) { 4615 // signal 4616 if (!signal_name(exception_code, buf, size)) { 4617 jio_snprintf(buf, size, "SIG%d", exception_code); 4618 } 4619 return buf; 4620 } else { 4621 return NULL; 4622 } 4623 } 4624 4625 // this is called _before_ the most of global arguments have been parsed 4626 void os::init(void) { 4627 char dummy; // used to get a guess on initial stack address 4628 // first_hrtime = gethrtime(); 4629 4630 // With LinuxThreads the JavaMain thread pid (primordial thread) 4631 // is different than the pid of the java launcher thread. 4632 // So, on Linux, the launcher thread pid is passed to the VM 4633 // via the sun.java.launcher.pid property. 4634 // Use this property instead of getpid() if it was correctly passed. 4635 // See bug 6351349. 4636 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4637 4638 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4639 4640 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4641 4642 init_random(1234567); 4643 4644 ThreadCritical::initialize(); 4645 4646 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4647 if (Linux::page_size() == -1) { 4648 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4649 strerror(errno))); 4650 } 4651 init_page_sizes((size_t) Linux::page_size()); 4652 4653 Linux::initialize_system_info(); 4654 4655 // main_thread points to the aboriginal thread 4656 Linux::_main_thread = pthread_self(); 4657 4658 Linux::clock_init(); 4659 initial_time_count = javaTimeNanos(); 4660 4661 // pthread_condattr initialization for monotonic clock 4662 int status; 4663 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4664 if ((status = pthread_condattr_init(_condattr)) != 0) { 4665 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4666 } 4667 // Only set the clock if CLOCK_MONOTONIC is available 4668 if (os::supports_monotonic_clock()) { 4669 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4670 if (status == EINVAL) { 4671 warning("Unable to use monotonic clock with relative timed-waits" \ 4672 " - changes to the time-of-day clock may have adverse affects"); 4673 } else { 4674 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4675 } 4676 } 4677 } 4678 // else it defaults to CLOCK_REALTIME 4679 4680 // If the pagesize of the VM is greater than 8K determine the appropriate 4681 // number of initial guard pages. The user can change this with the 4682 // command line arguments, if needed. 4683 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4684 StackYellowPages = 1; 4685 StackRedPages = 1; 4686 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4687 } 4688 4689 // retrieve entry point for pthread_setname_np 4690 Linux::_pthread_setname_np = 4691 (int(*)(pthread_t, const char*))dlsym(RTLD_DEFAULT, "pthread_setname_np"); 4692 4693 } 4694 4695 // To install functions for atexit system call 4696 extern "C" { 4697 static void perfMemory_exit_helper() { 4698 perfMemory_exit(); 4699 } 4700 } 4701 4702 // this is called _after_ the global arguments have been parsed 4703 jint os::init_2(void) { 4704 Linux::fast_thread_clock_init(); 4705 4706 // Allocate a single page and mark it as readable for safepoint polling 4707 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4708 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page"); 4709 4710 os::set_polling_page(polling_page); 4711 4712 #ifndef PRODUCT 4713 if (Verbose && PrintMiscellaneous) { 4714 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", 4715 (intptr_t)polling_page); 4716 } 4717 #endif 4718 4719 if (!UseMembar) { 4720 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4721 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4722 os::set_memory_serialize_page(mem_serialize_page); 4723 4724 #ifndef PRODUCT 4725 if (Verbose && PrintMiscellaneous) { 4726 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", 4727 (intptr_t)mem_serialize_page); 4728 } 4729 #endif 4730 } 4731 4732 // initialize suspend/resume support - must do this before signal_sets_init() 4733 if (SR_initialize() != 0) { 4734 perror("SR_initialize failed"); 4735 return JNI_ERR; 4736 } 4737 4738 Linux::signal_sets_init(); 4739 Linux::install_signal_handlers(); 4740 4741 // Check minimum allowable stack size for thread creation and to initialize 4742 // the java system classes, including StackOverflowError - depends on page 4743 // size. Add a page for compiler2 recursion in main thread. 4744 // Add in 2*BytesPerWord times page size to account for VM stack during 4745 // class initialization depending on 32 or 64 bit VM. 4746 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4747 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4748 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4749 4750 size_t threadStackSizeInBytes = ThreadStackSize * K; 4751 if (threadStackSizeInBytes != 0 && 4752 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4753 tty->print_cr("\nThe stack size specified is too small, " 4754 "Specify at least %dk", 4755 os::Linux::min_stack_allowed/ K); 4756 return JNI_ERR; 4757 } 4758 4759 // Make the stack size a multiple of the page size so that 4760 // the yellow/red zones can be guarded. 4761 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4762 vm_page_size())); 4763 4764 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4765 4766 #if defined(IA32) 4767 workaround_expand_exec_shield_cs_limit(); 4768 #endif 4769 4770 Linux::libpthread_init(); 4771 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4772 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4773 Linux::glibc_version(), Linux::libpthread_version(), 4774 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4775 } 4776 4777 if (UseNUMA) { 4778 if (!Linux::libnuma_init()) { 4779 UseNUMA = false; 4780 } else { 4781 if ((Linux::numa_max_node() < 1)) { 4782 // There's only one node(they start from 0), disable NUMA. 4783 UseNUMA = false; 4784 } 4785 } 4786 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4787 // we can make the adaptive lgrp chunk resizing work. If the user specified 4788 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4789 // disable adaptive resizing. 4790 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4791 if (FLAG_IS_DEFAULT(UseNUMA)) { 4792 UseNUMA = false; 4793 } else { 4794 if (FLAG_IS_DEFAULT(UseLargePages) && 4795 FLAG_IS_DEFAULT(UseSHM) && 4796 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4797 UseLargePages = false; 4798 } else if (UseAdaptiveSizePolicy || UseAdaptiveNUMAChunkSizing) { 4799 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing (-XX:-UseAdaptiveSizePolicy -XX:-UseAdaptiveNUMAChunkSizing)"); 4800 UseAdaptiveSizePolicy = false; 4801 UseAdaptiveNUMAChunkSizing = false; 4802 } 4803 } 4804 } 4805 if (!UseNUMA && ForceNUMA) { 4806 UseNUMA = true; 4807 } 4808 } 4809 4810 if (MaxFDLimit) { 4811 // set the number of file descriptors to max. print out error 4812 // if getrlimit/setrlimit fails but continue regardless. 4813 struct rlimit nbr_files; 4814 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4815 if (status != 0) { 4816 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4817 perror("os::init_2 getrlimit failed"); 4818 } 4819 } else { 4820 nbr_files.rlim_cur = nbr_files.rlim_max; 4821 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4822 if (status != 0) { 4823 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4824 perror("os::init_2 setrlimit failed"); 4825 } 4826 } 4827 } 4828 } 4829 4830 // Initialize lock used to serialize thread creation (see os::create_thread) 4831 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4832 4833 // at-exit methods are called in the reverse order of their registration. 4834 // atexit functions are called on return from main or as a result of a 4835 // call to exit(3C). There can be only 32 of these functions registered 4836 // and atexit() does not set errno. 4837 4838 if (PerfAllowAtExitRegistration) { 4839 // only register atexit functions if PerfAllowAtExitRegistration is set. 4840 // atexit functions can be delayed until process exit time, which 4841 // can be problematic for embedded VM situations. Embedded VMs should 4842 // call DestroyJavaVM() to assure that VM resources are released. 4843 4844 // note: perfMemory_exit_helper atexit function may be removed in 4845 // the future if the appropriate cleanup code can be added to the 4846 // VM_Exit VMOperation's doit method. 4847 if (atexit(perfMemory_exit_helper) != 0) { 4848 warning("os::init_2 atexit(perfMemory_exit_helper) failed"); 4849 } 4850 } 4851 4852 // initialize thread priority policy 4853 prio_init(); 4854 4855 return JNI_OK; 4856 } 4857 4858 // Mark the polling page as unreadable 4859 void os::make_polling_page_unreadable(void) { 4860 if (!guard_memory((char*)_polling_page, Linux::page_size())) { 4861 fatal("Could not disable polling page"); 4862 } 4863 } 4864 4865 // Mark the polling page as readable 4866 void os::make_polling_page_readable(void) { 4867 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4868 fatal("Could not enable polling page"); 4869 } 4870 } 4871 4872 int os::active_processor_count() { 4873 // Linux doesn't yet have a (official) notion of processor sets, 4874 // so just return the number of online processors. 4875 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4876 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4877 return online_cpus; 4878 } 4879 4880 void os::set_native_thread_name(const char *name) { 4881 if (Linux::_pthread_setname_np) { 4882 char buf [16]; // according to glibc manpage, 16 chars incl. '/0' 4883 snprintf(buf, sizeof(buf), "%s", name); 4884 buf[sizeof(buf) - 1] = '\0'; 4885 const int rc = Linux::_pthread_setname_np(pthread_self(), buf); 4886 // ERANGE should not happen; all other errors should just be ignored. 4887 assert(rc != ERANGE, "pthread_setname_np failed"); 4888 } 4889 } 4890 4891 bool os::distribute_processes(uint length, uint* distribution) { 4892 // Not yet implemented. 4893 return false; 4894 } 4895 4896 bool os::bind_to_processor(uint processor_id) { 4897 // Not yet implemented. 4898 return false; 4899 } 4900 4901 /// 4902 4903 void os::SuspendedThreadTask::internal_do_task() { 4904 if (do_suspend(_thread->osthread())) { 4905 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4906 do_task(context); 4907 do_resume(_thread->osthread()); 4908 } 4909 } 4910 4911 class PcFetcher : public os::SuspendedThreadTask { 4912 public: 4913 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4914 ExtendedPC result(); 4915 protected: 4916 void do_task(const os::SuspendedThreadTaskContext& context); 4917 private: 4918 ExtendedPC _epc; 4919 }; 4920 4921 ExtendedPC PcFetcher::result() { 4922 guarantee(is_done(), "task is not done yet."); 4923 return _epc; 4924 } 4925 4926 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 4927 Thread* thread = context.thread(); 4928 OSThread* osthread = thread->osthread(); 4929 if (osthread->ucontext() != NULL) { 4930 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 4931 } else { 4932 // NULL context is unexpected, double-check this is the VMThread 4933 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4934 } 4935 } 4936 4937 // Suspends the target using the signal mechanism and then grabs the PC before 4938 // resuming the target. Used by the flat-profiler only 4939 ExtendedPC os::get_thread_pc(Thread* thread) { 4940 // Make sure that it is called by the watcher for the VMThread 4941 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4942 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4943 4944 PcFetcher fetcher(thread); 4945 fetcher.run(); 4946 return fetcher.result(); 4947 } 4948 4949 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, 4950 pthread_mutex_t *_mutex, 4951 const struct timespec *_abstime) { 4952 if (is_NPTL()) { 4953 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4954 } else { 4955 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4956 // word back to default 64bit precision if condvar is signaled. Java 4957 // wants 53bit precision. Save and restore current value. 4958 int fpu = get_fpu_control_word(); 4959 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4960 set_fpu_control_word(fpu); 4961 return status; 4962 } 4963 } 4964 4965 //////////////////////////////////////////////////////////////////////////////// 4966 // debug support 4967 4968 bool os::find(address addr, outputStream* st) { 4969 Dl_info dlinfo; 4970 memset(&dlinfo, 0, sizeof(dlinfo)); 4971 if (dladdr(addr, &dlinfo) != 0) { 4972 st->print(PTR_FORMAT ": ", addr); 4973 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 4974 st->print("%s+%#x", dlinfo.dli_sname, 4975 addr - (intptr_t)dlinfo.dli_saddr); 4976 } else if (dlinfo.dli_fbase != NULL) { 4977 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4978 } else { 4979 st->print("<absolute address>"); 4980 } 4981 if (dlinfo.dli_fname != NULL) { 4982 st->print(" in %s", dlinfo.dli_fname); 4983 } 4984 if (dlinfo.dli_fbase != NULL) { 4985 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4986 } 4987 st->cr(); 4988 4989 if (Verbose) { 4990 // decode some bytes around the PC 4991 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 4992 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 4993 address lowest = (address) dlinfo.dli_sname; 4994 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4995 if (begin < lowest) begin = lowest; 4996 Dl_info dlinfo2; 4997 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 4998 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) { 4999 end = (address) dlinfo2.dli_saddr; 5000 } 5001 Disassembler::decode(begin, end, st); 5002 } 5003 return true; 5004 } 5005 return false; 5006 } 5007 5008 //////////////////////////////////////////////////////////////////////////////// 5009 // misc 5010 5011 // This does not do anything on Linux. This is basically a hook for being 5012 // able to use structured exception handling (thread-local exception filters) 5013 // on, e.g., Win32. 5014 void 5015 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 5016 JavaCallArguments* args, Thread* thread) { 5017 f(value, method, args, thread); 5018 } 5019 5020 void os::print_statistics() { 5021 } 5022 5023 int os::message_box(const char* title, const char* message) { 5024 int i; 5025 fdStream err(defaultStream::error_fd()); 5026 for (i = 0; i < 78; i++) err.print_raw("="); 5027 err.cr(); 5028 err.print_raw_cr(title); 5029 for (i = 0; i < 78; i++) err.print_raw("-"); 5030 err.cr(); 5031 err.print_raw_cr(message); 5032 for (i = 0; i < 78; i++) err.print_raw("="); 5033 err.cr(); 5034 5035 char buf[16]; 5036 // Prevent process from exiting upon "read error" without consuming all CPU 5037 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 5038 5039 return buf[0] == 'y' || buf[0] == 'Y'; 5040 } 5041 5042 int os::stat(const char *path, struct stat *sbuf) { 5043 char pathbuf[MAX_PATH]; 5044 if (strlen(path) > MAX_PATH - 1) { 5045 errno = ENAMETOOLONG; 5046 return -1; 5047 } 5048 os::native_path(strcpy(pathbuf, path)); 5049 return ::stat(pathbuf, sbuf); 5050 } 5051 5052 bool os::check_heap(bool force) { 5053 return true; 5054 } 5055 5056 // Is a (classpath) directory empty? 5057 bool os::dir_is_empty(const char* path) { 5058 DIR *dir = NULL; 5059 struct dirent *ptr; 5060 5061 dir = opendir(path); 5062 if (dir == NULL) return true; 5063 5064 // Scan the directory 5065 bool result = true; 5066 char buf[sizeof(struct dirent) + MAX_PATH]; 5067 while (result && (ptr = ::readdir(dir)) != NULL) { 5068 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5069 result = false; 5070 } 5071 } 5072 closedir(dir); 5073 return result; 5074 } 5075 5076 // This code originates from JDK's sysOpen and open64_w 5077 // from src/solaris/hpi/src/system_md.c 5078 5079 int os::open(const char *path, int oflag, int mode) { 5080 if (strlen(path) > MAX_PATH - 1) { 5081 errno = ENAMETOOLONG; 5082 return -1; 5083 } 5084 5085 // All file descriptors that are opened in the Java process and not 5086 // specifically destined for a subprocess should have the close-on-exec 5087 // flag set. If we don't set it, then careless 3rd party native code 5088 // might fork and exec without closing all appropriate file descriptors 5089 // (e.g. as we do in closeDescriptors in UNIXProcess.c), and this in 5090 // turn might: 5091 // 5092 // - cause end-of-file to fail to be detected on some file 5093 // descriptors, resulting in mysterious hangs, or 5094 // 5095 // - might cause an fopen in the subprocess to fail on a system 5096 // suffering from bug 1085341. 5097 // 5098 // (Yes, the default setting of the close-on-exec flag is a Unix 5099 // design flaw) 5100 // 5101 // See: 5102 // 1085341: 32-bit stdio routines should support file descriptors >255 5103 // 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5104 // 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5105 // 5106 // Modern Linux kernels (after 2.6.23 2007) support O_CLOEXEC with open(). 5107 // O_CLOEXEC is preferable to using FD_CLOEXEC on an open file descriptor 5108 // because it saves a system call and removes a small window where the flag 5109 // is unset. On ancient Linux kernels the O_CLOEXEC flag will be ignored 5110 // and we fall back to using FD_CLOEXEC (see below). 5111 #ifdef O_CLOEXEC 5112 oflag |= O_CLOEXEC; 5113 #endif 5114 5115 int fd = ::open64(path, oflag, mode); 5116 if (fd == -1) return -1; 5117 5118 //If the open succeeded, the file might still be a directory 5119 { 5120 struct stat64 buf64; 5121 int ret = ::fstat64(fd, &buf64); 5122 int st_mode = buf64.st_mode; 5123 5124 if (ret != -1) { 5125 if ((st_mode & S_IFMT) == S_IFDIR) { 5126 errno = EISDIR; 5127 ::close(fd); 5128 return -1; 5129 } 5130 } else { 5131 ::close(fd); 5132 return -1; 5133 } 5134 } 5135 5136 #ifdef FD_CLOEXEC 5137 // Validate that the use of the O_CLOEXEC flag on open above worked. 5138 // With recent kernels, we will perform this check exactly once. 5139 static sig_atomic_t O_CLOEXEC_is_known_to_work = 0; 5140 if (!O_CLOEXEC_is_known_to_work) { 5141 int flags = ::fcntl(fd, F_GETFD); 5142 if (flags != -1) { 5143 if ((flags & FD_CLOEXEC) != 0) 5144 O_CLOEXEC_is_known_to_work = 1; 5145 else 5146 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5147 } 5148 } 5149 #endif 5150 5151 return fd; 5152 } 5153 5154 5155 // create binary file, rewriting existing file if required 5156 int os::create_binary_file(const char* path, bool rewrite_existing) { 5157 int oflags = O_WRONLY | O_CREAT; 5158 if (!rewrite_existing) { 5159 oflags |= O_EXCL; 5160 } 5161 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5162 } 5163 5164 // return current position of file pointer 5165 jlong os::current_file_offset(int fd) { 5166 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5167 } 5168 5169 // move file pointer to the specified offset 5170 jlong os::seek_to_file_offset(int fd, jlong offset) { 5171 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5172 } 5173 5174 // This code originates from JDK's sysAvailable 5175 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5176 5177 int os::available(int fd, jlong *bytes) { 5178 jlong cur, end; 5179 int mode; 5180 struct stat64 buf64; 5181 5182 if (::fstat64(fd, &buf64) >= 0) { 5183 mode = buf64.st_mode; 5184 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5185 // XXX: is the following call interruptible? If so, this might 5186 // need to go through the INTERRUPT_IO() wrapper as for other 5187 // blocking, interruptible calls in this file. 5188 int n; 5189 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5190 *bytes = n; 5191 return 1; 5192 } 5193 } 5194 } 5195 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5196 return 0; 5197 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5198 return 0; 5199 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5200 return 0; 5201 } 5202 *bytes = end - cur; 5203 return 1; 5204 } 5205 5206 // Map a block of memory. 5207 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5208 char *addr, size_t bytes, bool read_only, 5209 bool allow_exec) { 5210 int prot; 5211 int flags = MAP_PRIVATE; 5212 5213 if (read_only) { 5214 prot = PROT_READ; 5215 } else { 5216 prot = PROT_READ | PROT_WRITE; 5217 } 5218 5219 if (allow_exec) { 5220 prot |= PROT_EXEC; 5221 } 5222 5223 if (addr != NULL) { 5224 flags |= MAP_FIXED; 5225 } 5226 5227 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5228 fd, file_offset); 5229 if (mapped_address == MAP_FAILED) { 5230 return NULL; 5231 } 5232 return mapped_address; 5233 } 5234 5235 5236 // Remap a block of memory. 5237 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5238 char *addr, size_t bytes, bool read_only, 5239 bool allow_exec) { 5240 // same as map_memory() on this OS 5241 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5242 allow_exec); 5243 } 5244 5245 5246 // Unmap a block of memory. 5247 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5248 return munmap(addr, bytes) == 0; 5249 } 5250 5251 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5252 5253 static clockid_t thread_cpu_clockid(Thread* thread) { 5254 pthread_t tid = thread->osthread()->pthread_id(); 5255 clockid_t clockid; 5256 5257 // Get thread clockid 5258 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5259 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5260 return clockid; 5261 } 5262 5263 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5264 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5265 // of a thread. 5266 // 5267 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5268 // the fast estimate available on the platform. 5269 5270 jlong os::current_thread_cpu_time() { 5271 if (os::Linux::supports_fast_thread_cpu_time()) { 5272 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5273 } else { 5274 // return user + sys since the cost is the same 5275 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5276 } 5277 } 5278 5279 jlong os::thread_cpu_time(Thread* thread) { 5280 // consistent with what current_thread_cpu_time() returns 5281 if (os::Linux::supports_fast_thread_cpu_time()) { 5282 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5283 } else { 5284 return slow_thread_cpu_time(thread, true /* user + sys */); 5285 } 5286 } 5287 5288 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5289 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5290 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5291 } else { 5292 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5293 } 5294 } 5295 5296 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5297 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5298 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5299 } else { 5300 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5301 } 5302 } 5303 5304 // -1 on error. 5305 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5306 pid_t tid = thread->osthread()->thread_id(); 5307 char *s; 5308 char stat[2048]; 5309 int statlen; 5310 char proc_name[64]; 5311 int count; 5312 long sys_time, user_time; 5313 char cdummy; 5314 int idummy; 5315 long ldummy; 5316 FILE *fp; 5317 5318 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid); 5319 fp = fopen(proc_name, "r"); 5320 if (fp == NULL) return -1; 5321 statlen = fread(stat, 1, 2047, fp); 5322 stat[statlen] = '\0'; 5323 fclose(fp); 5324 5325 // Skip pid and the command string. Note that we could be dealing with 5326 // weird command names, e.g. user could decide to rename java launcher 5327 // to "java 1.4.2 :)", then the stat file would look like 5328 // 1234 (java 1.4.2 :)) R ... ... 5329 // We don't really need to know the command string, just find the last 5330 // occurrence of ")" and then start parsing from there. See bug 4726580. 5331 s = strrchr(stat, ')'); 5332 if (s == NULL) return -1; 5333 5334 // Skip blank chars 5335 do { s++; } while (s && isspace(*s)); 5336 5337 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5338 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5339 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5340 &user_time, &sys_time); 5341 if (count != 13) return -1; 5342 if (user_sys_cpu_time) { 5343 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5344 } else { 5345 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5346 } 5347 } 5348 5349 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5350 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5351 info_ptr->may_skip_backward = false; // elapsed time not wall time 5352 info_ptr->may_skip_forward = false; // elapsed time not wall time 5353 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5354 } 5355 5356 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5357 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5358 info_ptr->may_skip_backward = false; // elapsed time not wall time 5359 info_ptr->may_skip_forward = false; // elapsed time not wall time 5360 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5361 } 5362 5363 bool os::is_thread_cpu_time_supported() { 5364 return true; 5365 } 5366 5367 // System loadavg support. Returns -1 if load average cannot be obtained. 5368 // Linux doesn't yet have a (official) notion of processor sets, 5369 // so just return the system wide load average. 5370 int os::loadavg(double loadavg[], int nelem) { 5371 return ::getloadavg(loadavg, nelem); 5372 } 5373 5374 void os::pause() { 5375 char filename[MAX_PATH]; 5376 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5377 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5378 } else { 5379 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5380 } 5381 5382 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5383 if (fd != -1) { 5384 struct stat buf; 5385 ::close(fd); 5386 while (::stat(filename, &buf) == 0) { 5387 (void)::poll(NULL, 0, 100); 5388 } 5389 } else { 5390 jio_fprintf(stderr, 5391 "Could not open pause file '%s', continuing immediately.\n", filename); 5392 } 5393 } 5394 5395 5396 // Refer to the comments in os_solaris.cpp park-unpark. The next two 5397 // comment paragraphs are worth repeating here: 5398 // 5399 // Assumption: 5400 // Only one parker can exist on an event, which is why we allocate 5401 // them per-thread. Multiple unparkers can coexist. 5402 // 5403 // _Event serves as a restricted-range semaphore. 5404 // -1 : thread is blocked, i.e. there is a waiter 5405 // 0 : neutral: thread is running or ready, 5406 // could have been signaled after a wait started 5407 // 1 : signaled - thread is running or ready 5408 // 5409 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5410 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5411 // For specifics regarding the bug see GLIBC BUGID 261237 : 5412 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5413 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5414 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5415 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5416 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5417 // and monitorenter when we're using 1-0 locking. All those operations may result in 5418 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5419 // of libpthread avoids the problem, but isn't practical. 5420 // 5421 // Possible remedies: 5422 // 5423 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5424 // This is palliative and probabilistic, however. If the thread is preempted 5425 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5426 // than the minimum period may have passed, and the abstime may be stale (in the 5427 // past) resultin in a hang. Using this technique reduces the odds of a hang 5428 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5429 // 5430 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5431 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5432 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5433 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5434 // thread. 5435 // 5436 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5437 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5438 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5439 // This also works well. In fact it avoids kernel-level scalability impediments 5440 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5441 // timers in a graceful fashion. 5442 // 5443 // 4. When the abstime value is in the past it appears that control returns 5444 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5445 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5446 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5447 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5448 // It may be possible to avoid reinitialization by checking the return 5449 // value from pthread_cond_timedwait(). In addition to reinitializing the 5450 // condvar we must establish the invariant that cond_signal() is only called 5451 // within critical sections protected by the adjunct mutex. This prevents 5452 // cond_signal() from "seeing" a condvar that's in the midst of being 5453 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5454 // desirable signal-after-unlock optimization that avoids futile context switching. 5455 // 5456 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5457 // structure when a condvar is used or initialized. cond_destroy() would 5458 // release the helper structure. Our reinitialize-after-timedwait fix 5459 // put excessive stress on malloc/free and locks protecting the c-heap. 5460 // 5461 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5462 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5463 // and only enabling the work-around for vulnerable environments. 5464 5465 // utility to compute the abstime argument to timedwait: 5466 // millis is the relative timeout time 5467 // abstime will be the absolute timeout time 5468 // TODO: replace compute_abstime() with unpackTime() 5469 5470 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5471 if (millis < 0) millis = 0; 5472 5473 jlong seconds = millis / 1000; 5474 millis %= 1000; 5475 if (seconds > 50000000) { // see man cond_timedwait(3T) 5476 seconds = 50000000; 5477 } 5478 5479 if (os::supports_monotonic_clock()) { 5480 struct timespec now; 5481 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5482 assert_status(status == 0, status, "clock_gettime"); 5483 abstime->tv_sec = now.tv_sec + seconds; 5484 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5485 if (nanos >= NANOSECS_PER_SEC) { 5486 abstime->tv_sec += 1; 5487 nanos -= NANOSECS_PER_SEC; 5488 } 5489 abstime->tv_nsec = nanos; 5490 } else { 5491 struct timeval now; 5492 int status = gettimeofday(&now, NULL); 5493 assert(status == 0, "gettimeofday"); 5494 abstime->tv_sec = now.tv_sec + seconds; 5495 long usec = now.tv_usec + millis * 1000; 5496 if (usec >= 1000000) { 5497 abstime->tv_sec += 1; 5498 usec -= 1000000; 5499 } 5500 abstime->tv_nsec = usec * 1000; 5501 } 5502 return abstime; 5503 } 5504 5505 void os::PlatformEvent::park() { // AKA "down()" 5506 // Transitions for _Event: 5507 // -1 => -1 : illegal 5508 // 1 => 0 : pass - return immediately 5509 // 0 => -1 : block; then set _Event to 0 before returning 5510 5511 // Invariant: Only the thread associated with the Event/PlatformEvent 5512 // may call park(). 5513 // TODO: assert that _Assoc != NULL or _Assoc == Self 5514 assert(_nParked == 0, "invariant"); 5515 5516 int v; 5517 for (;;) { 5518 v = _Event; 5519 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5520 } 5521 guarantee(v >= 0, "invariant"); 5522 if (v == 0) { 5523 // Do this the hard way by blocking ... 5524 int status = pthread_mutex_lock(_mutex); 5525 assert_status(status == 0, status, "mutex_lock"); 5526 guarantee(_nParked == 0, "invariant"); 5527 ++_nParked; 5528 while (_Event < 0) { 5529 status = pthread_cond_wait(_cond, _mutex); 5530 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5531 // Treat this the same as if the wait was interrupted 5532 if (status == ETIME) { status = EINTR; } 5533 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5534 } 5535 --_nParked; 5536 5537 _Event = 0; 5538 status = pthread_mutex_unlock(_mutex); 5539 assert_status(status == 0, status, "mutex_unlock"); 5540 // Paranoia to ensure our locked and lock-free paths interact 5541 // correctly with each other. 5542 OrderAccess::fence(); 5543 } 5544 guarantee(_Event >= 0, "invariant"); 5545 } 5546 5547 int os::PlatformEvent::park(jlong millis) { 5548 // Transitions for _Event: 5549 // -1 => -1 : illegal 5550 // 1 => 0 : pass - return immediately 5551 // 0 => -1 : block; then set _Event to 0 before returning 5552 5553 guarantee(_nParked == 0, "invariant"); 5554 5555 int v; 5556 for (;;) { 5557 v = _Event; 5558 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5559 } 5560 guarantee(v >= 0, "invariant"); 5561 if (v != 0) return OS_OK; 5562 5563 // We do this the hard way, by blocking the thread. 5564 // Consider enforcing a minimum timeout value. 5565 struct timespec abst; 5566 compute_abstime(&abst, millis); 5567 5568 int ret = OS_TIMEOUT; 5569 int status = pthread_mutex_lock(_mutex); 5570 assert_status(status == 0, status, "mutex_lock"); 5571 guarantee(_nParked == 0, "invariant"); 5572 ++_nParked; 5573 5574 // Object.wait(timo) will return because of 5575 // (a) notification 5576 // (b) timeout 5577 // (c) thread.interrupt 5578 // 5579 // Thread.interrupt and object.notify{All} both call Event::set. 5580 // That is, we treat thread.interrupt as a special case of notification. 5581 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false. 5582 // We assume all ETIME returns are valid. 5583 // 5584 // TODO: properly differentiate simultaneous notify+interrupt. 5585 // In that case, we should propagate the notify to another waiter. 5586 5587 while (_Event < 0) { 5588 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5589 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5590 pthread_cond_destroy(_cond); 5591 pthread_cond_init(_cond, os::Linux::condAttr()); 5592 } 5593 assert_status(status == 0 || status == EINTR || 5594 status == ETIME || status == ETIMEDOUT, 5595 status, "cond_timedwait"); 5596 if (!FilterSpuriousWakeups) break; // previous semantics 5597 if (status == ETIME || status == ETIMEDOUT) break; 5598 // We consume and ignore EINTR and spurious wakeups. 5599 } 5600 --_nParked; 5601 if (_Event >= 0) { 5602 ret = OS_OK; 5603 } 5604 _Event = 0; 5605 status = pthread_mutex_unlock(_mutex); 5606 assert_status(status == 0, status, "mutex_unlock"); 5607 assert(_nParked == 0, "invariant"); 5608 // Paranoia to ensure our locked and lock-free paths interact 5609 // correctly with each other. 5610 OrderAccess::fence(); 5611 return ret; 5612 } 5613 5614 void os::PlatformEvent::unpark() { 5615 // Transitions for _Event: 5616 // 0 => 1 : just return 5617 // 1 => 1 : just return 5618 // -1 => either 0 or 1; must signal target thread 5619 // That is, we can safely transition _Event from -1 to either 5620 // 0 or 1. 5621 // See also: "Semaphores in Plan 9" by Mullender & Cox 5622 // 5623 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5624 // that it will take two back-to-back park() calls for the owning 5625 // thread to block. This has the benefit of forcing a spurious return 5626 // from the first park() call after an unpark() call which will help 5627 // shake out uses of park() and unpark() without condition variables. 5628 5629 if (Atomic::xchg(1, &_Event) >= 0) return; 5630 5631 // Wait for the thread associated with the event to vacate 5632 int status = pthread_mutex_lock(_mutex); 5633 assert_status(status == 0, status, "mutex_lock"); 5634 int AnyWaiters = _nParked; 5635 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5636 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5637 AnyWaiters = 0; 5638 pthread_cond_signal(_cond); 5639 } 5640 status = pthread_mutex_unlock(_mutex); 5641 assert_status(status == 0, status, "mutex_unlock"); 5642 if (AnyWaiters != 0) { 5643 // Note that we signal() *after* dropping the lock for "immortal" Events. 5644 // This is safe and avoids a common class of futile wakeups. In rare 5645 // circumstances this can cause a thread to return prematurely from 5646 // cond_{timed}wait() but the spurious wakeup is benign and the victim 5647 // will simply re-test the condition and re-park itself. 5648 // This provides particular benefit if the underlying platform does not 5649 // provide wait morphing. 5650 status = pthread_cond_signal(_cond); 5651 assert_status(status == 0, status, "cond_signal"); 5652 } 5653 } 5654 5655 5656 // JSR166 5657 // ------------------------------------------------------- 5658 5659 // The solaris and linux implementations of park/unpark are fairly 5660 // conservative for now, but can be improved. They currently use a 5661 // mutex/condvar pair, plus a a count. 5662 // Park decrements count if > 0, else does a condvar wait. Unpark 5663 // sets count to 1 and signals condvar. Only one thread ever waits 5664 // on the condvar. Contention seen when trying to park implies that someone 5665 // is unparking you, so don't wait. And spurious returns are fine, so there 5666 // is no need to track notifications. 5667 5668 // This code is common to linux and solaris and will be moved to a 5669 // common place in dolphin. 5670 // 5671 // The passed in time value is either a relative time in nanoseconds 5672 // or an absolute time in milliseconds. Either way it has to be unpacked 5673 // into suitable seconds and nanoseconds components and stored in the 5674 // given timespec structure. 5675 // Given time is a 64-bit value and the time_t used in the timespec is only 5676 // a signed-32-bit value (except on 64-bit Linux) we have to watch for 5677 // overflow if times way in the future are given. Further on Solaris versions 5678 // prior to 10 there is a restriction (see cond_timedwait) that the specified 5679 // number of seconds, in abstime, is less than current_time + 100,000,000. 5680 // As it will be 28 years before "now + 100000000" will overflow we can 5681 // ignore overflow and just impose a hard-limit on seconds using the value 5682 // of "now + 100,000,000". This places a limit on the timeout of about 3.17 5683 // years from "now". 5684 5685 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5686 assert(time > 0, "convertTime"); 5687 time_t max_secs = 0; 5688 5689 if (!os::supports_monotonic_clock() || isAbsolute) { 5690 struct timeval now; 5691 int status = gettimeofday(&now, NULL); 5692 assert(status == 0, "gettimeofday"); 5693 5694 max_secs = now.tv_sec + MAX_SECS; 5695 5696 if (isAbsolute) { 5697 jlong secs = time / 1000; 5698 if (secs > max_secs) { 5699 absTime->tv_sec = max_secs; 5700 } else { 5701 absTime->tv_sec = secs; 5702 } 5703 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5704 } else { 5705 jlong secs = time / NANOSECS_PER_SEC; 5706 if (secs >= MAX_SECS) { 5707 absTime->tv_sec = max_secs; 5708 absTime->tv_nsec = 0; 5709 } else { 5710 absTime->tv_sec = now.tv_sec + secs; 5711 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5712 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5713 absTime->tv_nsec -= NANOSECS_PER_SEC; 5714 ++absTime->tv_sec; // note: this must be <= max_secs 5715 } 5716 } 5717 } 5718 } else { 5719 // must be relative using monotonic clock 5720 struct timespec now; 5721 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5722 assert_status(status == 0, status, "clock_gettime"); 5723 max_secs = now.tv_sec + MAX_SECS; 5724 jlong secs = time / NANOSECS_PER_SEC; 5725 if (secs >= MAX_SECS) { 5726 absTime->tv_sec = max_secs; 5727 absTime->tv_nsec = 0; 5728 } else { 5729 absTime->tv_sec = now.tv_sec + secs; 5730 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5731 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5732 absTime->tv_nsec -= NANOSECS_PER_SEC; 5733 ++absTime->tv_sec; // note: this must be <= max_secs 5734 } 5735 } 5736 } 5737 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5738 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5739 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5740 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5741 } 5742 5743 void Parker::park(bool isAbsolute, jlong time) { 5744 // Ideally we'd do something useful while spinning, such 5745 // as calling unpackTime(). 5746 5747 // Optional fast-path check: 5748 // Return immediately if a permit is available. 5749 // We depend on Atomic::xchg() having full barrier semantics 5750 // since we are doing a lock-free update to _counter. 5751 if (Atomic::xchg(0, &_counter) > 0) return; 5752 5753 Thread* thread = Thread::current(); 5754 assert(thread->is_Java_thread(), "Must be JavaThread"); 5755 JavaThread *jt = (JavaThread *)thread; 5756 5757 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5758 // Check interrupt before trying to wait 5759 if (Thread::is_interrupted(thread, false)) { 5760 return; 5761 } 5762 5763 // Next, demultiplex/decode time arguments 5764 timespec absTime; 5765 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all 5766 return; 5767 } 5768 if (time > 0) { 5769 unpackTime(&absTime, isAbsolute, time); 5770 } 5771 5772 5773 // Enter safepoint region 5774 // Beware of deadlocks such as 6317397. 5775 // The per-thread Parker:: mutex is a classic leaf-lock. 5776 // In particular a thread must never block on the Threads_lock while 5777 // holding the Parker:: mutex. If safepoints are pending both the 5778 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5779 ThreadBlockInVM tbivm(jt); 5780 5781 // Don't wait if cannot get lock since interference arises from 5782 // unblocking. Also. check interrupt before trying wait 5783 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5784 return; 5785 } 5786 5787 int status; 5788 if (_counter > 0) { // no wait needed 5789 _counter = 0; 5790 status = pthread_mutex_unlock(_mutex); 5791 assert(status == 0, "invariant"); 5792 // Paranoia to ensure our locked and lock-free paths interact 5793 // correctly with each other and Java-level accesses. 5794 OrderAccess::fence(); 5795 return; 5796 } 5797 5798 #ifdef ASSERT 5799 // Don't catch signals while blocked; let the running threads have the signals. 5800 // (This allows a debugger to break into the running thread.) 5801 sigset_t oldsigs; 5802 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5803 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5804 #endif 5805 5806 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5807 jt->set_suspend_equivalent(); 5808 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5809 5810 assert(_cur_index == -1, "invariant"); 5811 if (time == 0) { 5812 _cur_index = REL_INDEX; // arbitrary choice when not timed 5813 status = pthread_cond_wait(&_cond[_cur_index], _mutex); 5814 } else { 5815 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5816 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime); 5817 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5818 pthread_cond_destroy(&_cond[_cur_index]); 5819 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5820 } 5821 } 5822 _cur_index = -1; 5823 assert_status(status == 0 || status == EINTR || 5824 status == ETIME || status == ETIMEDOUT, 5825 status, "cond_timedwait"); 5826 5827 #ifdef ASSERT 5828 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5829 #endif 5830 5831 _counter = 0; 5832 status = pthread_mutex_unlock(_mutex); 5833 assert_status(status == 0, status, "invariant"); 5834 // Paranoia to ensure our locked and lock-free paths interact 5835 // correctly with each other and Java-level accesses. 5836 OrderAccess::fence(); 5837 5838 // If externally suspended while waiting, re-suspend 5839 if (jt->handle_special_suspend_equivalent_condition()) { 5840 jt->java_suspend_self(); 5841 } 5842 } 5843 5844 void Parker::unpark() { 5845 int status = pthread_mutex_lock(_mutex); 5846 assert(status == 0, "invariant"); 5847 const int s = _counter; 5848 _counter = 1; 5849 if (s < 1) { 5850 // thread might be parked 5851 if (_cur_index != -1) { 5852 // thread is definitely parked 5853 if (WorkAroundNPTLTimedWaitHang) { 5854 status = pthread_cond_signal(&_cond[_cur_index]); 5855 assert(status == 0, "invariant"); 5856 status = pthread_mutex_unlock(_mutex); 5857 assert(status == 0, "invariant"); 5858 } else { 5859 status = pthread_mutex_unlock(_mutex); 5860 assert(status == 0, "invariant"); 5861 status = pthread_cond_signal(&_cond[_cur_index]); 5862 assert(status == 0, "invariant"); 5863 } 5864 } else { 5865 pthread_mutex_unlock(_mutex); 5866 assert(status == 0, "invariant"); 5867 } 5868 } else { 5869 pthread_mutex_unlock(_mutex); 5870 assert(status == 0, "invariant"); 5871 } 5872 } 5873 5874 5875 extern char** environ; 5876 5877 // Run the specified command in a separate process. Return its exit value, 5878 // or -1 on failure (e.g. can't fork a new process). 5879 // Unlike system(), this function can be called from signal handler. It 5880 // doesn't block SIGINT et al. 5881 int os::fork_and_exec(char* cmd) { 5882 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5883 5884 pid_t pid = fork(); 5885 5886 if (pid < 0) { 5887 // fork failed 5888 return -1; 5889 5890 } else if (pid == 0) { 5891 // child process 5892 5893 execve("/bin/sh", (char* const*)argv, environ); 5894 5895 // execve failed 5896 _exit(-1); 5897 5898 } else { 5899 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5900 // care about the actual exit code, for now. 5901 5902 int status; 5903 5904 // Wait for the child process to exit. This returns immediately if 5905 // the child has already exited. */ 5906 while (waitpid(pid, &status, 0) < 0) { 5907 switch (errno) { 5908 case ECHILD: return 0; 5909 case EINTR: break; 5910 default: return -1; 5911 } 5912 } 5913 5914 if (WIFEXITED(status)) { 5915 // The child exited normally; get its exit code. 5916 return WEXITSTATUS(status); 5917 } else if (WIFSIGNALED(status)) { 5918 // The child exited because of a signal 5919 // The best value to return is 0x80 + signal number, 5920 // because that is what all Unix shells do, and because 5921 // it allows callers to distinguish between process exit and 5922 // process death by signal. 5923 return 0x80 + WTERMSIG(status); 5924 } else { 5925 // Unknown exit code; pass it through 5926 return status; 5927 } 5928 } 5929 } 5930 5931 // is_headless_jre() 5932 // 5933 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 5934 // in order to report if we are running in a headless jre 5935 // 5936 // Since JDK8 xawt/libmawt.so was moved into the same directory 5937 // as libawt.so, and renamed libawt_xawt.so 5938 // 5939 bool os::is_headless_jre() { 5940 struct stat statbuf; 5941 char buf[MAXPATHLEN]; 5942 char libmawtpath[MAXPATHLEN]; 5943 const char *xawtstr = "/xawt/libmawt.so"; 5944 const char *new_xawtstr = "/libawt_xawt.so"; 5945 char *p; 5946 5947 // Get path to libjvm.so 5948 os::jvm_path(buf, sizeof(buf)); 5949 5950 // Get rid of libjvm.so 5951 p = strrchr(buf, '/'); 5952 if (p == NULL) { 5953 return false; 5954 } else { 5955 *p = '\0'; 5956 } 5957 5958 // Get rid of client or server 5959 p = strrchr(buf, '/'); 5960 if (p == NULL) { 5961 return false; 5962 } else { 5963 *p = '\0'; 5964 } 5965 5966 // check xawt/libmawt.so 5967 strcpy(libmawtpath, buf); 5968 strcat(libmawtpath, xawtstr); 5969 if (::stat(libmawtpath, &statbuf) == 0) return false; 5970 5971 // check libawt_xawt.so 5972 strcpy(libmawtpath, buf); 5973 strcat(libmawtpath, new_xawtstr); 5974 if (::stat(libmawtpath, &statbuf) == 0) return false; 5975 5976 return true; 5977 } 5978 5979 // Get the default path to the core file 5980 // Returns the length of the string 5981 int os::get_core_path(char* buffer, size_t bufferSize) { 5982 /* 5983 * Max length of /proc/sys/kernel/core_pattern is 128 characters. 5984 * See https://www.kernel.org/doc/Documentation/sysctl/kernel.txt 5985 */ 5986 const int core_pattern_len = 129; 5987 char core_pattern[core_pattern_len] = {0}; 5988 5989 int core_pattern_file = ::open("/proc/sys/kernel/core_pattern", O_RDONLY); 5990 if (core_pattern_file != -1) { 5991 ssize_t ret = ::read(core_pattern_file, core_pattern, core_pattern_len); 5992 ::close(core_pattern_file); 5993 5994 if (ret > 0) { 5995 char *last_char = core_pattern + strlen(core_pattern) - 1; 5996 5997 if (*last_char == '\n') { 5998 *last_char = '\0'; 5999 } 6000 } 6001 } 6002 6003 if (strlen(core_pattern) == 0) { 6004 return -1; 6005 } 6006 6007 char *pid_pos = strstr(core_pattern, "%p"); 6008 int written; 6009 6010 if (core_pattern[0] == '/') { 6011 written = jio_snprintf(buffer, bufferSize, core_pattern); 6012 } else { 6013 char cwd[PATH_MAX]; 6014 6015 const char* p = get_current_directory(cwd, PATH_MAX); 6016 if (p == NULL) { 6017 return -1; 6018 } 6019 6020 if (core_pattern[0] == '|') { 6021 written = jio_snprintf(buffer, bufferSize, 6022 "\"%s\" (or dumping to %s/core.%d)", 6023 &core_pattern[1], p, current_process_id()); 6024 } else { 6025 written = jio_snprintf(buffer, bufferSize, "%s/%s", p, core_pattern); 6026 } 6027 } 6028 6029 if (written < 0) { 6030 return -1; 6031 } 6032 6033 if (((size_t)written < bufferSize) && (pid_pos == NULL) && (core_pattern[0] != '|')) { 6034 int core_uses_pid_file = ::open("/proc/sys/kernel/core_uses_pid", O_RDONLY); 6035 6036 if (core_uses_pid_file != -1) { 6037 char core_uses_pid = 0; 6038 ssize_t ret = ::read(core_uses_pid_file, &core_uses_pid, 1); 6039 ::close(core_uses_pid_file); 6040 6041 if (core_uses_pid == '1') { 6042 jio_snprintf(buffer + written, bufferSize - written, 6043 ".%d", current_process_id()); 6044 } 6045 } 6046 } 6047 6048 return strlen(buffer); 6049 } 6050 6051 /////////////// Unit tests /////////////// 6052 6053 #ifndef PRODUCT 6054 6055 #define test_log(...) \ 6056 do { \ 6057 if (VerboseInternalVMTests) { \ 6058 tty->print_cr(__VA_ARGS__); \ 6059 tty->flush(); \ 6060 } \ 6061 } while (false) 6062 6063 class TestReserveMemorySpecial : AllStatic { 6064 public: 6065 static void small_page_write(void* addr, size_t size) { 6066 size_t page_size = os::vm_page_size(); 6067 6068 char* end = (char*)addr + size; 6069 for (char* p = (char*)addr; p < end; p += page_size) { 6070 *p = 1; 6071 } 6072 } 6073 6074 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6075 if (!UseHugeTLBFS) { 6076 return; 6077 } 6078 6079 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6080 6081 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6082 6083 if (addr != NULL) { 6084 small_page_write(addr, size); 6085 6086 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6087 } 6088 } 6089 6090 static void test_reserve_memory_special_huge_tlbfs_only() { 6091 if (!UseHugeTLBFS) { 6092 return; 6093 } 6094 6095 size_t lp = os::large_page_size(); 6096 6097 for (size_t size = lp; size <= lp * 10; size += lp) { 6098 test_reserve_memory_special_huge_tlbfs_only(size); 6099 } 6100 } 6101 6102 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6103 size_t lp = os::large_page_size(); 6104 size_t ag = os::vm_allocation_granularity(); 6105 6106 // sizes to test 6107 const size_t sizes[] = { 6108 lp, lp + ag, lp + lp / 2, lp * 2, 6109 lp * 2 + ag, lp * 2 - ag, lp * 2 + lp / 2, 6110 lp * 10, lp * 10 + lp / 2 6111 }; 6112 const int num_sizes = sizeof(sizes) / sizeof(size_t); 6113 6114 // For each size/alignment combination, we test three scenarios: 6115 // 1) with req_addr == NULL 6116 // 2) with a non-null req_addr at which we expect to successfully allocate 6117 // 3) with a non-null req_addr which contains a pre-existing mapping, at which we 6118 // expect the allocation to either fail or to ignore req_addr 6119 6120 // Pre-allocate two areas; they shall be as large as the largest allocation 6121 // and aligned to the largest alignment we will be testing. 6122 const size_t mapping_size = sizes[num_sizes - 1] * 2; 6123 char* const mapping1 = (char*) ::mmap(NULL, mapping_size, 6124 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, 6125 -1, 0); 6126 assert(mapping1 != MAP_FAILED, "should work"); 6127 6128 char* const mapping2 = (char*) ::mmap(NULL, mapping_size, 6129 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, 6130 -1, 0); 6131 assert(mapping2 != MAP_FAILED, "should work"); 6132 6133 // Unmap the first mapping, but leave the second mapping intact: the first 6134 // mapping will serve as a value for a "good" req_addr (case 2). The second 6135 // mapping, still intact, as "bad" req_addr (case 3). 6136 ::munmap(mapping1, mapping_size); 6137 6138 // Case 1 6139 test_log("%s, req_addr NULL:", __FUNCTION__); 6140 test_log("size align result"); 6141 6142 for (int i = 0; i < num_sizes; i++) { 6143 const size_t size = sizes[i]; 6144 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6145 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6146 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " -> " PTR_FORMAT " %s", 6147 size, alignment, p, (p != NULL ? "" : "(failed)")); 6148 if (p != NULL) { 6149 assert(is_ptr_aligned(p, alignment), "must be"); 6150 small_page_write(p, size); 6151 os::Linux::release_memory_special_huge_tlbfs(p, size); 6152 } 6153 } 6154 } 6155 6156 // Case 2 6157 test_log("%s, req_addr non-NULL:", __FUNCTION__); 6158 test_log("size align req_addr result"); 6159 6160 for (int i = 0; i < num_sizes; i++) { 6161 const size_t size = sizes[i]; 6162 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6163 char* const req_addr = (char*) align_ptr_up(mapping1, alignment); 6164 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false); 6165 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s", 6166 size, alignment, req_addr, p, 6167 ((p != NULL ? (p == req_addr ? "(exact match)" : "") : "(failed)"))); 6168 if (p != NULL) { 6169 assert(p == req_addr, "must be"); 6170 small_page_write(p, size); 6171 os::Linux::release_memory_special_huge_tlbfs(p, size); 6172 } 6173 } 6174 } 6175 6176 // Case 3 6177 test_log("%s, req_addr non-NULL with preexisting mapping:", __FUNCTION__); 6178 test_log("size align req_addr result"); 6179 6180 for (int i = 0; i < num_sizes; i++) { 6181 const size_t size = sizes[i]; 6182 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6183 char* const req_addr = (char*) align_ptr_up(mapping2, alignment); 6184 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false); 6185 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s", 6186 size, alignment, req_addr, p, 6187 ((p != NULL ? "" : "(failed)"))); 6188 // as the area around req_addr contains already existing mappings, the API should always 6189 // return NULL (as per contract, it cannot return another address) 6190 assert(p == NULL, "must be"); 6191 } 6192 } 6193 6194 ::munmap(mapping2, mapping_size); 6195 6196 } 6197 6198 static void test_reserve_memory_special_huge_tlbfs() { 6199 if (!UseHugeTLBFS) { 6200 return; 6201 } 6202 6203 test_reserve_memory_special_huge_tlbfs_only(); 6204 test_reserve_memory_special_huge_tlbfs_mixed(); 6205 } 6206 6207 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6208 if (!UseSHM) { 6209 return; 6210 } 6211 6212 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6213 6214 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6215 6216 if (addr != NULL) { 6217 assert(is_ptr_aligned(addr, alignment), "Check"); 6218 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6219 6220 small_page_write(addr, size); 6221 6222 os::Linux::release_memory_special_shm(addr, size); 6223 } 6224 } 6225 6226 static void test_reserve_memory_special_shm() { 6227 size_t lp = os::large_page_size(); 6228 size_t ag = os::vm_allocation_granularity(); 6229 6230 for (size_t size = ag; size < lp * 3; size += ag) { 6231 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6232 test_reserve_memory_special_shm(size, alignment); 6233 } 6234 } 6235 } 6236 6237 static void test() { 6238 test_reserve_memory_special_huge_tlbfs(); 6239 test_reserve_memory_special_shm(); 6240 } 6241 }; 6242 6243 void TestReserveMemorySpecial_test() { 6244 TestReserveMemorySpecial::test(); 6245 } 6246 6247 #endif