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) { 1482 abort(dump_core, NULL, NULL); 1483 } 1484 1485 void os::abort(bool dump_core, void* siginfo, void* context) { 1486 os::shutdown(); 1487 if (dump_core) { 1488 #ifndef PRODUCT 1489 fdStream out(defaultStream::output_fd()); 1490 out.print_raw("Current thread is "); 1491 char buf[16]; 1492 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1493 out.print_raw_cr(buf); 1494 out.print_raw_cr("Dumping core ..."); 1495 #endif 1496 ::abort(); // dump core 1497 } 1498 1499 ::exit(1); 1500 } 1501 1502 // Die immediately, no exit hook, no abort hook, no cleanup. 1503 void os::die() { 1504 // _exit() on LinuxThreads only kills current thread 1505 ::abort(); 1506 } 1507 1508 1509 // This method is a copy of JDK's sysGetLastErrorString 1510 // from src/solaris/hpi/src/system_md.c 1511 1512 size_t os::lasterror(char *buf, size_t len) { 1513 if (errno == 0) return 0; 1514 1515 const char *s = ::strerror(errno); 1516 size_t n = ::strlen(s); 1517 if (n >= len) { 1518 n = len - 1; 1519 } 1520 ::strncpy(buf, s, n); 1521 buf[n] = '\0'; 1522 return n; 1523 } 1524 1525 intx os::current_thread_id() { return (intx)pthread_self(); } 1526 int os::current_process_id() { 1527 1528 // Under the old linux thread library, linux gives each thread 1529 // its own process id. Because of this each thread will return 1530 // a different pid if this method were to return the result 1531 // of getpid(2). Linux provides no api that returns the pid 1532 // of the launcher thread for the vm. This implementation 1533 // returns a unique pid, the pid of the launcher thread 1534 // that starts the vm 'process'. 1535 1536 // Under the NPTL, getpid() returns the same pid as the 1537 // launcher thread rather than a unique pid per thread. 1538 // Use gettid() if you want the old pre NPTL behaviour. 1539 1540 // if you are looking for the result of a call to getpid() that 1541 // returns a unique pid for the calling thread, then look at the 1542 // OSThread::thread_id() method in osThread_linux.hpp file 1543 1544 return (int)(_initial_pid ? _initial_pid : getpid()); 1545 } 1546 1547 // DLL functions 1548 1549 const char* os::dll_file_extension() { return ".so"; } 1550 1551 // This must be hard coded because it's the system's temporary 1552 // directory not the java application's temp directory, ala java.io.tmpdir. 1553 const char* os::get_temp_directory() { return "/tmp"; } 1554 1555 static bool file_exists(const char* filename) { 1556 struct stat statbuf; 1557 if (filename == NULL || strlen(filename) == 0) { 1558 return false; 1559 } 1560 return os::stat(filename, &statbuf) == 0; 1561 } 1562 1563 bool os::dll_build_name(char* buffer, size_t buflen, 1564 const char* pname, const char* fname) { 1565 bool retval = false; 1566 // Copied from libhpi 1567 const size_t pnamelen = pname ? strlen(pname) : 0; 1568 1569 // Return error on buffer overflow. 1570 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1571 return retval; 1572 } 1573 1574 if (pnamelen == 0) { 1575 snprintf(buffer, buflen, "lib%s.so", fname); 1576 retval = true; 1577 } else if (strchr(pname, *os::path_separator()) != NULL) { 1578 int n; 1579 char** pelements = split_path(pname, &n); 1580 if (pelements == NULL) { 1581 return false; 1582 } 1583 for (int i = 0; i < n; i++) { 1584 // Really shouldn't be NULL, but check can't hurt 1585 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1586 continue; // skip the empty path values 1587 } 1588 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1589 if (file_exists(buffer)) { 1590 retval = true; 1591 break; 1592 } 1593 } 1594 // release the storage 1595 for (int i = 0; i < n; i++) { 1596 if (pelements[i] != NULL) { 1597 FREE_C_HEAP_ARRAY(char, pelements[i]); 1598 } 1599 } 1600 if (pelements != NULL) { 1601 FREE_C_HEAP_ARRAY(char*, pelements); 1602 } 1603 } else { 1604 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1605 retval = true; 1606 } 1607 return retval; 1608 } 1609 1610 // check if addr is inside libjvm.so 1611 bool os::address_is_in_vm(address addr) { 1612 static address libjvm_base_addr; 1613 Dl_info dlinfo; 1614 1615 if (libjvm_base_addr == NULL) { 1616 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) { 1617 libjvm_base_addr = (address)dlinfo.dli_fbase; 1618 } 1619 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1620 } 1621 1622 if (dladdr((void *)addr, &dlinfo) != 0) { 1623 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1624 } 1625 1626 return false; 1627 } 1628 1629 bool os::dll_address_to_function_name(address addr, char *buf, 1630 int buflen, int *offset) { 1631 // buf is not optional, but offset is optional 1632 assert(buf != NULL, "sanity check"); 1633 1634 Dl_info dlinfo; 1635 1636 if (dladdr((void*)addr, &dlinfo) != 0) { 1637 // see if we have a matching symbol 1638 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) { 1639 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) { 1640 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1641 } 1642 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr; 1643 return true; 1644 } 1645 // no matching symbol so try for just file info 1646 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) { 1647 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase), 1648 buf, buflen, offset, dlinfo.dli_fname)) { 1649 return true; 1650 } 1651 } 1652 } 1653 1654 buf[0] = '\0'; 1655 if (offset != NULL) *offset = -1; 1656 return false; 1657 } 1658 1659 struct _address_to_library_name { 1660 address addr; // input : memory address 1661 size_t buflen; // size of fname 1662 char* fname; // output: library name 1663 address base; // library base addr 1664 }; 1665 1666 static int address_to_library_name_callback(struct dl_phdr_info *info, 1667 size_t size, void *data) { 1668 int i; 1669 bool found = false; 1670 address libbase = NULL; 1671 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1672 1673 // iterate through all loadable segments 1674 for (i = 0; i < info->dlpi_phnum; i++) { 1675 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1676 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1677 // base address of a library is the lowest address of its loaded 1678 // segments. 1679 if (libbase == NULL || libbase > segbase) { 1680 libbase = segbase; 1681 } 1682 // see if 'addr' is within current segment 1683 if (segbase <= d->addr && 1684 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1685 found = true; 1686 } 1687 } 1688 } 1689 1690 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1691 // so dll_address_to_library_name() can fall through to use dladdr() which 1692 // can figure out executable name from argv[0]. 1693 if (found && info->dlpi_name && info->dlpi_name[0]) { 1694 d->base = libbase; 1695 if (d->fname) { 1696 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1697 } 1698 return 1; 1699 } 1700 return 0; 1701 } 1702 1703 bool os::dll_address_to_library_name(address addr, char* buf, 1704 int buflen, int* offset) { 1705 // buf is not optional, but offset is optional 1706 assert(buf != NULL, "sanity check"); 1707 1708 Dl_info dlinfo; 1709 struct _address_to_library_name data; 1710 1711 // There is a bug in old glibc dladdr() implementation that it could resolve 1712 // to wrong library name if the .so file has a base address != NULL. Here 1713 // we iterate through the program headers of all loaded libraries to find 1714 // out which library 'addr' really belongs to. This workaround can be 1715 // removed once the minimum requirement for glibc is moved to 2.3.x. 1716 data.addr = addr; 1717 data.fname = buf; 1718 data.buflen = buflen; 1719 data.base = NULL; 1720 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1721 1722 if (rslt) { 1723 // buf already contains library name 1724 if (offset) *offset = addr - data.base; 1725 return true; 1726 } 1727 if (dladdr((void*)addr, &dlinfo) != 0) { 1728 if (dlinfo.dli_fname != NULL) { 1729 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1730 } 1731 if (dlinfo.dli_fbase != NULL && offset != NULL) { 1732 *offset = addr - (address)dlinfo.dli_fbase; 1733 } 1734 return true; 1735 } 1736 1737 buf[0] = '\0'; 1738 if (offset) *offset = -1; 1739 return false; 1740 } 1741 1742 // Loads .dll/.so and 1743 // in case of error it checks if .dll/.so was built for the 1744 // same architecture as Hotspot is running on 1745 1746 1747 // Remember the stack's state. The Linux dynamic linker will change 1748 // the stack to 'executable' at most once, so we must safepoint only once. 1749 bool os::Linux::_stack_is_executable = false; 1750 1751 // VM operation that loads a library. This is necessary if stack protection 1752 // of the Java stacks can be lost during loading the library. If we 1753 // do not stop the Java threads, they can stack overflow before the stacks 1754 // are protected again. 1755 class VM_LinuxDllLoad: public VM_Operation { 1756 private: 1757 const char *_filename; 1758 char *_ebuf; 1759 int _ebuflen; 1760 void *_lib; 1761 public: 1762 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) : 1763 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {} 1764 VMOp_Type type() const { return VMOp_LinuxDllLoad; } 1765 void doit() { 1766 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen); 1767 os::Linux::_stack_is_executable = true; 1768 } 1769 void* loaded_library() { return _lib; } 1770 }; 1771 1772 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) { 1773 void * result = NULL; 1774 bool load_attempted = false; 1775 1776 // Check whether the library to load might change execution rights 1777 // of the stack. If they are changed, the protection of the stack 1778 // guard pages will be lost. We need a safepoint to fix this. 1779 // 1780 // See Linux man page execstack(8) for more info. 1781 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) { 1782 ElfFile ef(filename); 1783 if (!ef.specifies_noexecstack()) { 1784 if (!is_init_completed()) { 1785 os::Linux::_stack_is_executable = true; 1786 // This is OK - No Java threads have been created yet, and hence no 1787 // stack guard pages to fix. 1788 // 1789 // This should happen only when you are building JDK7 using a very 1790 // old version of JDK6 (e.g., with JPRT) and running test_gamma. 1791 // 1792 // Dynamic loader will make all stacks executable after 1793 // this function returns, and will not do that again. 1794 assert(Threads::first() == NULL, "no Java threads should exist yet."); 1795 } else { 1796 warning("You have loaded library %s which might have disabled stack guard. " 1797 "The VM will try to fix the stack guard now.\n" 1798 "It's highly recommended that you fix the library with " 1799 "'execstack -c <libfile>', or link it with '-z noexecstack'.", 1800 filename); 1801 1802 assert(Thread::current()->is_Java_thread(), "must be Java thread"); 1803 JavaThread *jt = JavaThread::current(); 1804 if (jt->thread_state() != _thread_in_native) { 1805 // This happens when a compiler thread tries to load a hsdis-<arch>.so file 1806 // that requires ExecStack. Cannot enter safe point. Let's give up. 1807 warning("Unable to fix stack guard. Giving up."); 1808 } else { 1809 if (!LoadExecStackDllInVMThread) { 1810 // This is for the case where the DLL has an static 1811 // constructor function that executes JNI code. We cannot 1812 // load such DLLs in the VMThread. 1813 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1814 } 1815 1816 ThreadInVMfromNative tiv(jt); 1817 debug_only(VMNativeEntryWrapper vew;) 1818 1819 VM_LinuxDllLoad op(filename, ebuf, ebuflen); 1820 VMThread::execute(&op); 1821 if (LoadExecStackDllInVMThread) { 1822 result = op.loaded_library(); 1823 } 1824 load_attempted = true; 1825 } 1826 } 1827 } 1828 } 1829 1830 if (!load_attempted) { 1831 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen); 1832 } 1833 1834 if (result != NULL) { 1835 // Successful loading 1836 return result; 1837 } 1838 1839 Elf32_Ehdr elf_head; 1840 int diag_msg_max_length=ebuflen-strlen(ebuf); 1841 char* diag_msg_buf=ebuf+strlen(ebuf); 1842 1843 if (diag_msg_max_length==0) { 1844 // No more space in ebuf for additional diagnostics message 1845 return NULL; 1846 } 1847 1848 1849 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1850 1851 if (file_descriptor < 0) { 1852 // Can't open library, report dlerror() message 1853 return NULL; 1854 } 1855 1856 bool failed_to_read_elf_head= 1857 (sizeof(elf_head)!= 1858 (::read(file_descriptor, &elf_head,sizeof(elf_head)))); 1859 1860 ::close(file_descriptor); 1861 if (failed_to_read_elf_head) { 1862 // file i/o error - report dlerror() msg 1863 return NULL; 1864 } 1865 1866 typedef struct { 1867 Elf32_Half code; // Actual value as defined in elf.h 1868 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1869 char elf_class; // 32 or 64 bit 1870 char endianess; // MSB or LSB 1871 char* name; // String representation 1872 } arch_t; 1873 1874 #ifndef EM_486 1875 #define EM_486 6 /* Intel 80486 */ 1876 #endif 1877 #ifndef EM_AARCH64 1878 #define EM_AARCH64 183 /* ARM AARCH64 */ 1879 #endif 1880 1881 static const arch_t arch_array[]={ 1882 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1883 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1884 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1885 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1886 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1887 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1888 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1889 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1890 #if defined(VM_LITTLE_ENDIAN) 1891 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"}, 1892 #else 1893 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1894 #endif 1895 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1896 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1897 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1898 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1899 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1900 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1901 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}, 1902 {EM_AARCH64, EM_AARCH64, ELFCLASS64, ELFDATA2LSB, (char*)"AARCH64"}, 1903 }; 1904 1905 #if (defined IA32) 1906 static Elf32_Half running_arch_code=EM_386; 1907 #elif (defined AMD64) 1908 static Elf32_Half running_arch_code=EM_X86_64; 1909 #elif (defined IA64) 1910 static Elf32_Half running_arch_code=EM_IA_64; 1911 #elif (defined __sparc) && (defined _LP64) 1912 static Elf32_Half running_arch_code=EM_SPARCV9; 1913 #elif (defined __sparc) && (!defined _LP64) 1914 static Elf32_Half running_arch_code=EM_SPARC; 1915 #elif (defined __powerpc64__) 1916 static Elf32_Half running_arch_code=EM_PPC64; 1917 #elif (defined __powerpc__) 1918 static Elf32_Half running_arch_code=EM_PPC; 1919 #elif (defined ARM) 1920 static Elf32_Half running_arch_code=EM_ARM; 1921 #elif (defined S390) 1922 static Elf32_Half running_arch_code=EM_S390; 1923 #elif (defined ALPHA) 1924 static Elf32_Half running_arch_code=EM_ALPHA; 1925 #elif (defined MIPSEL) 1926 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1927 #elif (defined PARISC) 1928 static Elf32_Half running_arch_code=EM_PARISC; 1929 #elif (defined MIPS) 1930 static Elf32_Half running_arch_code=EM_MIPS; 1931 #elif (defined M68K) 1932 static Elf32_Half running_arch_code=EM_68K; 1933 #elif (defined AARCH64) 1934 static Elf32_Half running_arch_code=EM_AARCH64; 1935 #else 1936 #error Method os::dll_load requires that one of following is defined:\ 1937 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K, AARCH64 1938 #endif 1939 1940 // Identify compatability class for VM's architecture and library's architecture 1941 // Obtain string descriptions for architectures 1942 1943 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1944 int running_arch_index=-1; 1945 1946 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) { 1947 if (running_arch_code == arch_array[i].code) { 1948 running_arch_index = i; 1949 } 1950 if (lib_arch.code == arch_array[i].code) { 1951 lib_arch.compat_class = arch_array[i].compat_class; 1952 lib_arch.name = arch_array[i].name; 1953 } 1954 } 1955 1956 assert(running_arch_index != -1, 1957 "Didn't find running architecture code (running_arch_code) in arch_array"); 1958 if (running_arch_index == -1) { 1959 // Even though running architecture detection failed 1960 // we may still continue with reporting dlerror() message 1961 return NULL; 1962 } 1963 1964 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1965 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1966 return NULL; 1967 } 1968 1969 #ifndef S390 1970 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 1971 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 1972 return NULL; 1973 } 1974 #endif // !S390 1975 1976 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 1977 if (lib_arch.name!=NULL) { 1978 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1979 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 1980 lib_arch.name, arch_array[running_arch_index].name); 1981 } else { 1982 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1983 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 1984 lib_arch.code, 1985 arch_array[running_arch_index].name); 1986 } 1987 } 1988 1989 return NULL; 1990 } 1991 1992 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, 1993 int ebuflen) { 1994 void * result = ::dlopen(filename, RTLD_LAZY); 1995 if (result == NULL) { 1996 ::strncpy(ebuf, ::dlerror(), ebuflen - 1); 1997 ebuf[ebuflen-1] = '\0'; 1998 } 1999 return result; 2000 } 2001 2002 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, 2003 int ebuflen) { 2004 void * result = NULL; 2005 if (LoadExecStackDllInVMThread) { 2006 result = dlopen_helper(filename, ebuf, ebuflen); 2007 } 2008 2009 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a 2010 // library that requires an executable stack, or which does not have this 2011 // stack attribute set, dlopen changes the stack attribute to executable. The 2012 // read protection of the guard pages gets lost. 2013 // 2014 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad 2015 // may have been queued at the same time. 2016 2017 if (!_stack_is_executable) { 2018 JavaThread *jt = Threads::first(); 2019 2020 while (jt) { 2021 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized 2022 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions 2023 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(), 2024 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) { 2025 warning("Attempt to reguard stack yellow zone failed."); 2026 } 2027 } 2028 jt = jt->next(); 2029 } 2030 } 2031 2032 return result; 2033 } 2034 2035 void* os::dll_lookup(void* handle, const char* name) { 2036 void* res = dlsym(handle, name); 2037 return res; 2038 } 2039 2040 void* os::get_default_process_handle() { 2041 return (void*)::dlopen(NULL, RTLD_LAZY); 2042 } 2043 2044 static bool _print_ascii_file(const char* filename, outputStream* st) { 2045 int fd = ::open(filename, O_RDONLY); 2046 if (fd == -1) { 2047 return false; 2048 } 2049 2050 char buf[32]; 2051 int bytes; 2052 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) { 2053 st->print_raw(buf, bytes); 2054 } 2055 2056 ::close(fd); 2057 2058 return true; 2059 } 2060 2061 void os::print_dll_info(outputStream *st) { 2062 st->print_cr("Dynamic libraries:"); 2063 2064 char fname[32]; 2065 pid_t pid = os::Linux::gettid(); 2066 2067 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 2068 2069 if (!_print_ascii_file(fname, st)) { 2070 st->print("Can not get library information for pid = %d\n", pid); 2071 } 2072 } 2073 2074 int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) { 2075 FILE *procmapsFile = NULL; 2076 2077 // Open the procfs maps file for the current process 2078 if ((procmapsFile = fopen("/proc/self/maps", "r")) != NULL) { 2079 // Allocate PATH_MAX for file name plus a reasonable size for other fields. 2080 char line[PATH_MAX + 100]; 2081 2082 // Read line by line from 'file' 2083 while (fgets(line, sizeof(line), procmapsFile) != NULL) { 2084 u8 base, top, offset, inode; 2085 char permissions[5]; 2086 char device[6]; 2087 char name[PATH_MAX + 1]; 2088 2089 // Parse fields from line 2090 sscanf(line, "%lx-%lx %4s %lx %5s %ld %s", &base, &top, permissions, &offset, device, &inode, name); 2091 2092 // Filter by device id '00:00' so that we only get file system mapped files. 2093 if (strcmp(device, "00:00") != 0) { 2094 2095 // Call callback with the fields of interest 2096 if(callback(name, (address)base, (address)top, param)) { 2097 // Oops abort, callback aborted 2098 fclose(procmapsFile); 2099 return 1; 2100 } 2101 } 2102 } 2103 fclose(procmapsFile); 2104 } 2105 return 0; 2106 } 2107 2108 void os::print_os_info_brief(outputStream* st) { 2109 os::Linux::print_distro_info(st); 2110 2111 os::Posix::print_uname_info(st); 2112 2113 os::Linux::print_libversion_info(st); 2114 2115 } 2116 2117 void os::print_os_info(outputStream* st) { 2118 st->print("OS:"); 2119 2120 os::Linux::print_distro_info(st); 2121 2122 os::Posix::print_uname_info(st); 2123 2124 // Print warning if unsafe chroot environment detected 2125 if (unsafe_chroot_detected) { 2126 st->print("WARNING!! "); 2127 st->print_cr("%s", unstable_chroot_error); 2128 } 2129 2130 os::Linux::print_libversion_info(st); 2131 2132 os::Posix::print_rlimit_info(st); 2133 2134 os::Posix::print_load_average(st); 2135 2136 os::Linux::print_full_memory_info(st); 2137 } 2138 2139 // Try to identify popular distros. 2140 // Most Linux distributions have a /etc/XXX-release file, which contains 2141 // the OS version string. Newer Linux distributions have a /etc/lsb-release 2142 // file that also contains the OS version string. Some have more than one 2143 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and 2144 // /etc/redhat-release.), so the order is important. 2145 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have 2146 // their own specific XXX-release file as well as a redhat-release file. 2147 // Because of this the XXX-release file needs to be searched for before the 2148 // redhat-release file. 2149 // Since Red Hat has a lsb-release file that is not very descriptive the 2150 // search for redhat-release needs to be before lsb-release. 2151 // Since the lsb-release file is the new standard it needs to be searched 2152 // before the older style release files. 2153 // Searching system-release (Red Hat) and os-release (other Linuxes) are a 2154 // next to last resort. The os-release file is a new standard that contains 2155 // distribution information and the system-release file seems to be an old 2156 // standard that has been replaced by the lsb-release and os-release files. 2157 // Searching for the debian_version file is the last resort. It contains 2158 // an informative string like "6.0.6" or "wheezy/sid". Because of this 2159 // "Debian " is printed before the contents of the debian_version file. 2160 void os::Linux::print_distro_info(outputStream* st) { 2161 if (!_print_ascii_file("/etc/oracle-release", st) && 2162 !_print_ascii_file("/etc/mandriva-release", st) && 2163 !_print_ascii_file("/etc/mandrake-release", st) && 2164 !_print_ascii_file("/etc/sun-release", st) && 2165 !_print_ascii_file("/etc/redhat-release", st) && 2166 !_print_ascii_file("/etc/lsb-release", st) && 2167 !_print_ascii_file("/etc/SuSE-release", st) && 2168 !_print_ascii_file("/etc/turbolinux-release", st) && 2169 !_print_ascii_file("/etc/gentoo-release", st) && 2170 !_print_ascii_file("/etc/ltib-release", st) && 2171 !_print_ascii_file("/etc/angstrom-version", st) && 2172 !_print_ascii_file("/etc/system-release", st) && 2173 !_print_ascii_file("/etc/os-release", st)) { 2174 2175 if (file_exists("/etc/debian_version")) { 2176 st->print("Debian "); 2177 _print_ascii_file("/etc/debian_version", st); 2178 } else { 2179 st->print("Linux"); 2180 } 2181 } 2182 st->cr(); 2183 } 2184 2185 void os::Linux::print_libversion_info(outputStream* st) { 2186 // libc, pthread 2187 st->print("libc:"); 2188 st->print("%s ", os::Linux::glibc_version()); 2189 st->print("%s ", os::Linux::libpthread_version()); 2190 if (os::Linux::is_LinuxThreads()) { 2191 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 2192 } 2193 st->cr(); 2194 } 2195 2196 void os::Linux::print_full_memory_info(outputStream* st) { 2197 st->print("\n/proc/meminfo:\n"); 2198 _print_ascii_file("/proc/meminfo", st); 2199 st->cr(); 2200 } 2201 2202 void os::print_memory_info(outputStream* st) { 2203 2204 st->print("Memory:"); 2205 st->print(" %dk page", os::vm_page_size()>>10); 2206 2207 // values in struct sysinfo are "unsigned long" 2208 struct sysinfo si; 2209 sysinfo(&si); 2210 2211 st->print(", physical " UINT64_FORMAT "k", 2212 os::physical_memory() >> 10); 2213 st->print("(" UINT64_FORMAT "k free)", 2214 os::available_memory() >> 10); 2215 st->print(", swap " UINT64_FORMAT "k", 2216 ((jlong)si.totalswap * si.mem_unit) >> 10); 2217 st->print("(" UINT64_FORMAT "k free)", 2218 ((jlong)si.freeswap * si.mem_unit) >> 10); 2219 st->cr(); 2220 } 2221 2222 void os::pd_print_cpu_info(outputStream* st) { 2223 st->print("\n/proc/cpuinfo:\n"); 2224 if (!_print_ascii_file("/proc/cpuinfo", st)) { 2225 st->print(" <Not Available>"); 2226 } 2227 st->cr(); 2228 } 2229 2230 void os::print_siginfo(outputStream* st, void* siginfo) { 2231 const siginfo_t* si = (const siginfo_t*)siginfo; 2232 2233 os::Posix::print_siginfo_brief(st, si); 2234 #if INCLUDE_CDS 2235 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2236 UseSharedSpaces) { 2237 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2238 if (mapinfo->is_in_shared_space(si->si_addr)) { 2239 st->print("\n\nError accessing class data sharing archive." \ 2240 " Mapped file inaccessible during execution, " \ 2241 " possible disk/network problem."); 2242 } 2243 } 2244 #endif 2245 st->cr(); 2246 } 2247 2248 2249 static void print_signal_handler(outputStream* st, int sig, 2250 char* buf, size_t buflen); 2251 2252 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2253 st->print_cr("Signal Handlers:"); 2254 print_signal_handler(st, SIGSEGV, buf, buflen); 2255 print_signal_handler(st, SIGBUS , buf, buflen); 2256 print_signal_handler(st, SIGFPE , buf, buflen); 2257 print_signal_handler(st, SIGPIPE, buf, buflen); 2258 print_signal_handler(st, SIGXFSZ, buf, buflen); 2259 print_signal_handler(st, SIGILL , buf, buflen); 2260 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2261 print_signal_handler(st, SR_signum, buf, buflen); 2262 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2263 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2264 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2265 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2266 #if defined(PPC64) 2267 print_signal_handler(st, SIGTRAP, buf, buflen); 2268 #endif 2269 } 2270 2271 static char saved_jvm_path[MAXPATHLEN] = {0}; 2272 2273 // Find the full path to the current module, libjvm.so 2274 void os::jvm_path(char *buf, jint buflen) { 2275 // Error checking. 2276 if (buflen < MAXPATHLEN) { 2277 assert(false, "must use a large-enough buffer"); 2278 buf[0] = '\0'; 2279 return; 2280 } 2281 // Lazy resolve the path to current module. 2282 if (saved_jvm_path[0] != 0) { 2283 strcpy(buf, saved_jvm_path); 2284 return; 2285 } 2286 2287 char dli_fname[MAXPATHLEN]; 2288 bool ret = dll_address_to_library_name( 2289 CAST_FROM_FN_PTR(address, os::jvm_path), 2290 dli_fname, sizeof(dli_fname), NULL); 2291 assert(ret, "cannot locate libjvm"); 2292 char *rp = NULL; 2293 if (ret && dli_fname[0] != '\0') { 2294 rp = realpath(dli_fname, buf); 2295 } 2296 if (rp == NULL) { 2297 return; 2298 } 2299 2300 if (Arguments::sun_java_launcher_is_altjvm()) { 2301 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical 2302 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". 2303 // If "/jre/lib/" appears at the right place in the string, then 2304 // assume we are installed in a JDK and we're done. Otherwise, check 2305 // for a JAVA_HOME environment variable and fix up the path so it 2306 // looks like libjvm.so is installed there (append a fake suffix 2307 // hotspot/libjvm.so). 2308 const char *p = buf + strlen(buf) - 1; 2309 for (int count = 0; p > buf && count < 5; ++count) { 2310 for (--p; p > buf && *p != '/'; --p) 2311 /* empty */ ; 2312 } 2313 2314 if (strncmp(p, "/jre/lib/", 9) != 0) { 2315 // Look for JAVA_HOME in the environment. 2316 char* java_home_var = ::getenv("JAVA_HOME"); 2317 if (java_home_var != NULL && java_home_var[0] != 0) { 2318 char* jrelib_p; 2319 int len; 2320 2321 // Check the current module name "libjvm.so". 2322 p = strrchr(buf, '/'); 2323 if (p == NULL) { 2324 return; 2325 } 2326 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2327 2328 rp = realpath(java_home_var, buf); 2329 if (rp == NULL) { 2330 return; 2331 } 2332 2333 // determine if this is a legacy image or modules image 2334 // modules image doesn't have "jre" subdirectory 2335 len = strlen(buf); 2336 assert(len < buflen, "Ran out of buffer room"); 2337 jrelib_p = buf + len; 2338 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch); 2339 if (0 != access(buf, F_OK)) { 2340 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch); 2341 } 2342 2343 if (0 == access(buf, F_OK)) { 2344 // Use current module name "libjvm.so" 2345 len = strlen(buf); 2346 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so"); 2347 } else { 2348 // Go back to path of .so 2349 rp = realpath(dli_fname, buf); 2350 if (rp == NULL) { 2351 return; 2352 } 2353 } 2354 } 2355 } 2356 } 2357 2358 strncpy(saved_jvm_path, buf, MAXPATHLEN); 2359 saved_jvm_path[MAXPATHLEN - 1] = '\0'; 2360 } 2361 2362 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2363 // no prefix required, not even "_" 2364 } 2365 2366 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2367 // no suffix required 2368 } 2369 2370 //////////////////////////////////////////////////////////////////////////////// 2371 // sun.misc.Signal support 2372 2373 static volatile jint sigint_count = 0; 2374 2375 static void UserHandler(int sig, void *siginfo, void *context) { 2376 // 4511530 - sem_post is serialized and handled by the manager thread. When 2377 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2378 // don't want to flood the manager thread with sem_post requests. 2379 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) { 2380 return; 2381 } 2382 2383 // Ctrl-C is pressed during error reporting, likely because the error 2384 // handler fails to abort. Let VM die immediately. 2385 if (sig == SIGINT && is_error_reported()) { 2386 os::die(); 2387 } 2388 2389 os::signal_notify(sig); 2390 } 2391 2392 void* os::user_handler() { 2393 return CAST_FROM_FN_PTR(void*, UserHandler); 2394 } 2395 2396 class Semaphore : public StackObj { 2397 public: 2398 Semaphore(); 2399 ~Semaphore(); 2400 void signal(); 2401 void wait(); 2402 bool trywait(); 2403 bool timedwait(unsigned int sec, int nsec); 2404 private: 2405 sem_t _semaphore; 2406 }; 2407 2408 Semaphore::Semaphore() { 2409 sem_init(&_semaphore, 0, 0); 2410 } 2411 2412 Semaphore::~Semaphore() { 2413 sem_destroy(&_semaphore); 2414 } 2415 2416 void Semaphore::signal() { 2417 sem_post(&_semaphore); 2418 } 2419 2420 void Semaphore::wait() { 2421 sem_wait(&_semaphore); 2422 } 2423 2424 bool Semaphore::trywait() { 2425 return sem_trywait(&_semaphore) == 0; 2426 } 2427 2428 bool Semaphore::timedwait(unsigned int sec, int nsec) { 2429 2430 struct timespec ts; 2431 // Semaphore's are always associated with CLOCK_REALTIME 2432 os::Linux::clock_gettime(CLOCK_REALTIME, &ts); 2433 // see unpackTime for discussion on overflow checking 2434 if (sec >= MAX_SECS) { 2435 ts.tv_sec += MAX_SECS; 2436 ts.tv_nsec = 0; 2437 } else { 2438 ts.tv_sec += sec; 2439 ts.tv_nsec += nsec; 2440 if (ts.tv_nsec >= NANOSECS_PER_SEC) { 2441 ts.tv_nsec -= NANOSECS_PER_SEC; 2442 ++ts.tv_sec; // note: this must be <= max_secs 2443 } 2444 } 2445 2446 while (1) { 2447 int result = sem_timedwait(&_semaphore, &ts); 2448 if (result == 0) { 2449 return true; 2450 } else if (errno == EINTR) { 2451 continue; 2452 } else if (errno == ETIMEDOUT) { 2453 return false; 2454 } else { 2455 return false; 2456 } 2457 } 2458 } 2459 2460 extern "C" { 2461 typedef void (*sa_handler_t)(int); 2462 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2463 } 2464 2465 void* os::signal(int signal_number, void* handler) { 2466 struct sigaction sigAct, oldSigAct; 2467 2468 sigfillset(&(sigAct.sa_mask)); 2469 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2470 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2471 2472 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2473 // -1 means registration failed 2474 return (void *)-1; 2475 } 2476 2477 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2478 } 2479 2480 void os::signal_raise(int signal_number) { 2481 ::raise(signal_number); 2482 } 2483 2484 // The following code is moved from os.cpp for making this 2485 // code platform specific, which it is by its very nature. 2486 2487 // Will be modified when max signal is changed to be dynamic 2488 int os::sigexitnum_pd() { 2489 return NSIG; 2490 } 2491 2492 // a counter for each possible signal value 2493 static volatile jint pending_signals[NSIG+1] = { 0 }; 2494 2495 // Linux(POSIX) specific hand shaking semaphore. 2496 static sem_t sig_sem; 2497 static Semaphore sr_semaphore; 2498 2499 void os::signal_init_pd() { 2500 // Initialize signal structures 2501 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2502 2503 // Initialize signal semaphore 2504 ::sem_init(&sig_sem, 0, 0); 2505 } 2506 2507 void os::signal_notify(int sig) { 2508 Atomic::inc(&pending_signals[sig]); 2509 ::sem_post(&sig_sem); 2510 } 2511 2512 static int check_pending_signals(bool wait) { 2513 Atomic::store(0, &sigint_count); 2514 for (;;) { 2515 for (int i = 0; i < NSIG + 1; i++) { 2516 jint n = pending_signals[i]; 2517 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2518 return i; 2519 } 2520 } 2521 if (!wait) { 2522 return -1; 2523 } 2524 JavaThread *thread = JavaThread::current(); 2525 ThreadBlockInVM tbivm(thread); 2526 2527 bool threadIsSuspended; 2528 do { 2529 thread->set_suspend_equivalent(); 2530 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2531 ::sem_wait(&sig_sem); 2532 2533 // were we externally suspended while we were waiting? 2534 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2535 if (threadIsSuspended) { 2536 // The semaphore has been incremented, but while we were waiting 2537 // another thread suspended us. We don't want to continue running 2538 // while suspended because that would surprise the thread that 2539 // suspended us. 2540 ::sem_post(&sig_sem); 2541 2542 thread->java_suspend_self(); 2543 } 2544 } while (threadIsSuspended); 2545 } 2546 } 2547 2548 int os::signal_lookup() { 2549 return check_pending_signals(false); 2550 } 2551 2552 int os::signal_wait() { 2553 return check_pending_signals(true); 2554 } 2555 2556 //////////////////////////////////////////////////////////////////////////////// 2557 // Virtual Memory 2558 2559 int os::vm_page_size() { 2560 // Seems redundant as all get out 2561 assert(os::Linux::page_size() != -1, "must call os::init"); 2562 return os::Linux::page_size(); 2563 } 2564 2565 // Solaris allocates memory by pages. 2566 int os::vm_allocation_granularity() { 2567 assert(os::Linux::page_size() != -1, "must call os::init"); 2568 return os::Linux::page_size(); 2569 } 2570 2571 // Rationale behind this function: 2572 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2573 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2574 // samples for JITted code. Here we create private executable mapping over the code cache 2575 // and then we can use standard (well, almost, as mapping can change) way to provide 2576 // info for the reporting script by storing timestamp and location of symbol 2577 void linux_wrap_code(char* base, size_t size) { 2578 static volatile jint cnt = 0; 2579 2580 if (!UseOprofile) { 2581 return; 2582 } 2583 2584 char buf[PATH_MAX+1]; 2585 int num = Atomic::add(1, &cnt); 2586 2587 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2588 os::get_temp_directory(), os::current_process_id(), num); 2589 unlink(buf); 2590 2591 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU); 2592 2593 if (fd != -1) { 2594 off_t rv = ::lseek(fd, size-2, SEEK_SET); 2595 if (rv != (off_t)-1) { 2596 if (::write(fd, "", 1) == 1) { 2597 mmap(base, size, 2598 PROT_READ|PROT_WRITE|PROT_EXEC, 2599 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2600 } 2601 } 2602 ::close(fd); 2603 unlink(buf); 2604 } 2605 } 2606 2607 static bool recoverable_mmap_error(int err) { 2608 // See if the error is one we can let the caller handle. This 2609 // list of errno values comes from JBS-6843484. I can't find a 2610 // Linux man page that documents this specific set of errno 2611 // values so while this list currently matches Solaris, it may 2612 // change as we gain experience with this failure mode. 2613 switch (err) { 2614 case EBADF: 2615 case EINVAL: 2616 case ENOTSUP: 2617 // let the caller deal with these errors 2618 return true; 2619 2620 default: 2621 // Any remaining errors on this OS can cause our reserved mapping 2622 // to be lost. That can cause confusion where different data 2623 // structures think they have the same memory mapped. The worst 2624 // scenario is if both the VM and a library think they have the 2625 // same memory mapped. 2626 return false; 2627 } 2628 } 2629 2630 static void warn_fail_commit_memory(char* addr, size_t size, bool exec, 2631 int err) { 2632 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2633 ", %d) failed; error='%s' (errno=%d)", addr, size, exec, 2634 strerror(err), err); 2635 } 2636 2637 static void warn_fail_commit_memory(char* addr, size_t size, 2638 size_t alignment_hint, bool exec, 2639 int err) { 2640 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT 2641 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size, 2642 alignment_hint, exec, strerror(err), err); 2643 } 2644 2645 // NOTE: Linux kernel does not really reserve the pages for us. 2646 // All it does is to check if there are enough free pages 2647 // left at the time of mmap(). This could be a potential 2648 // problem. 2649 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) { 2650 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2651 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2652 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2653 if (res != (uintptr_t) MAP_FAILED) { 2654 if (UseNUMAInterleaving) { 2655 numa_make_global(addr, size); 2656 } 2657 return 0; 2658 } 2659 2660 int err = errno; // save errno from mmap() call above 2661 2662 if (!recoverable_mmap_error(err)) { 2663 warn_fail_commit_memory(addr, size, exec, err); 2664 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory."); 2665 } 2666 2667 return err; 2668 } 2669 2670 bool os::pd_commit_memory(char* addr, size_t size, bool exec) { 2671 return os::Linux::commit_memory_impl(addr, size, exec) == 0; 2672 } 2673 2674 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec, 2675 const char* mesg) { 2676 assert(mesg != NULL, "mesg must be specified"); 2677 int err = os::Linux::commit_memory_impl(addr, size, exec); 2678 if (err != 0) { 2679 // the caller wants all commit errors to exit with the specified mesg: 2680 warn_fail_commit_memory(addr, size, exec, err); 2681 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2682 } 2683 } 2684 2685 // Define MAP_HUGETLB here so we can build HotSpot on old systems. 2686 #ifndef MAP_HUGETLB 2687 #define MAP_HUGETLB 0x40000 2688 #endif 2689 2690 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems. 2691 #ifndef MADV_HUGEPAGE 2692 #define MADV_HUGEPAGE 14 2693 #endif 2694 2695 int os::Linux::commit_memory_impl(char* addr, size_t size, 2696 size_t alignment_hint, bool exec) { 2697 int err = os::Linux::commit_memory_impl(addr, size, exec); 2698 if (err == 0) { 2699 realign_memory(addr, size, alignment_hint); 2700 } 2701 return err; 2702 } 2703 2704 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, 2705 bool exec) { 2706 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0; 2707 } 2708 2709 void os::pd_commit_memory_or_exit(char* addr, size_t size, 2710 size_t alignment_hint, bool exec, 2711 const char* mesg) { 2712 assert(mesg != NULL, "mesg must be specified"); 2713 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec); 2714 if (err != 0) { 2715 // the caller wants all commit errors to exit with the specified mesg: 2716 warn_fail_commit_memory(addr, size, alignment_hint, exec, err); 2717 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg); 2718 } 2719 } 2720 2721 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) { 2722 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) { 2723 // We don't check the return value: madvise(MADV_HUGEPAGE) may not 2724 // be supported or the memory may already be backed by huge pages. 2725 ::madvise(addr, bytes, MADV_HUGEPAGE); 2726 } 2727 } 2728 2729 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) { 2730 // This method works by doing an mmap over an existing mmaping and effectively discarding 2731 // the existing pages. However it won't work for SHM-based large pages that cannot be 2732 // uncommitted at all. We don't do anything in this case to avoid creating a segment with 2733 // small pages on top of the SHM segment. This method always works for small pages, so we 2734 // allow that in any case. 2735 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) { 2736 commit_memory(addr, bytes, alignment_hint, !ExecMem); 2737 } 2738 } 2739 2740 void os::numa_make_global(char *addr, size_t bytes) { 2741 Linux::numa_interleave_memory(addr, bytes); 2742 } 2743 2744 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the 2745 // bind policy to MPOL_PREFERRED for the current thread. 2746 #define USE_MPOL_PREFERRED 0 2747 2748 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2749 // To make NUMA and large pages more robust when both enabled, we need to ease 2750 // the requirements on where the memory should be allocated. MPOL_BIND is the 2751 // default policy and it will force memory to be allocated on the specified 2752 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on 2753 // the specified node, but will not force it. Using this policy will prevent 2754 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no 2755 // free large pages. 2756 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED); 2757 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2758 } 2759 2760 bool os::numa_topology_changed() { return false; } 2761 2762 size_t os::numa_get_groups_num() { 2763 int max_node = Linux::numa_max_node(); 2764 return max_node > 0 ? max_node + 1 : 1; 2765 } 2766 2767 int os::numa_get_group_id() { 2768 int cpu_id = Linux::sched_getcpu(); 2769 if (cpu_id != -1) { 2770 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2771 if (lgrp_id != -1) { 2772 return lgrp_id; 2773 } 2774 } 2775 return 0; 2776 } 2777 2778 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2779 for (size_t i = 0; i < size; i++) { 2780 ids[i] = i; 2781 } 2782 return size; 2783 } 2784 2785 bool os::get_page_info(char *start, page_info* info) { 2786 return false; 2787 } 2788 2789 char *os::scan_pages(char *start, char* end, page_info* page_expected, 2790 page_info* page_found) { 2791 return end; 2792 } 2793 2794 2795 int os::Linux::sched_getcpu_syscall(void) { 2796 unsigned int cpu; 2797 int retval = -1; 2798 2799 #if defined(IA32) 2800 #ifndef SYS_getcpu 2801 #define SYS_getcpu 318 2802 #endif 2803 retval = syscall(SYS_getcpu, &cpu, NULL, NULL); 2804 #elif defined(AMD64) 2805 // Unfortunately we have to bring all these macros here from vsyscall.h 2806 // to be able to compile on old linuxes. 2807 #define __NR_vgetcpu 2 2808 #define VSYSCALL_START (-10UL << 20) 2809 #define VSYSCALL_SIZE 1024 2810 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) 2811 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache); 2812 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu); 2813 retval = vgetcpu(&cpu, NULL, NULL); 2814 #endif 2815 2816 return (retval == -1) ? retval : cpu; 2817 } 2818 2819 // Something to do with the numa-aware allocator needs these symbols 2820 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { } 2821 extern "C" JNIEXPORT void numa_error(char *where) { } 2822 extern "C" JNIEXPORT int fork1() { return fork(); } 2823 2824 2825 // If we are running with libnuma version > 2, then we should 2826 // be trying to use symbols with versions 1.1 2827 // If we are running with earlier version, which did not have symbol versions, 2828 // we should use the base version. 2829 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2830 void *f = dlvsym(handle, name, "libnuma_1.1"); 2831 if (f == NULL) { 2832 f = dlsym(handle, name); 2833 } 2834 return f; 2835 } 2836 2837 bool os::Linux::libnuma_init() { 2838 // sched_getcpu() should be in libc. 2839 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2840 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2841 2842 // If it's not, try a direct syscall. 2843 if (sched_getcpu() == -1) { 2844 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2845 (void*)&sched_getcpu_syscall)); 2846 } 2847 2848 if (sched_getcpu() != -1) { // Does it work? 2849 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2850 if (handle != NULL) { 2851 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2852 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2853 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2854 libnuma_dlsym(handle, "numa_max_node"))); 2855 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2856 libnuma_dlsym(handle, "numa_available"))); 2857 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2858 libnuma_dlsym(handle, "numa_tonode_memory"))); 2859 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2860 libnuma_dlsym(handle, "numa_interleave_memory"))); 2861 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t, 2862 libnuma_dlsym(handle, "numa_set_bind_policy"))); 2863 2864 2865 if (numa_available() != -1) { 2866 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2867 // Create a cpu -> node mapping 2868 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true); 2869 rebuild_cpu_to_node_map(); 2870 return true; 2871 } 2872 } 2873 } 2874 return false; 2875 } 2876 2877 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2878 // The table is later used in get_node_by_cpu(). 2879 void os::Linux::rebuild_cpu_to_node_map() { 2880 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2881 // in libnuma (possible values are starting from 16, 2882 // and continuing up with every other power of 2, but less 2883 // than the maximum number of CPUs supported by kernel), and 2884 // is a subject to change (in libnuma version 2 the requirements 2885 // are more reasonable) we'll just hardcode the number they use 2886 // in the library. 2887 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2888 2889 size_t cpu_num = os::active_processor_count(); 2890 size_t cpu_map_size = NCPUS / BitsPerCLong; 2891 size_t cpu_map_valid_size = 2892 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2893 2894 cpu_to_node()->clear(); 2895 cpu_to_node()->at_grow(cpu_num - 1); 2896 size_t node_num = numa_get_groups_num(); 2897 2898 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal); 2899 for (size_t i = 0; i < node_num; i++) { 2900 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2901 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2902 if (cpu_map[j] != 0) { 2903 for (size_t k = 0; k < BitsPerCLong; k++) { 2904 if (cpu_map[j] & (1UL << k)) { 2905 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2906 } 2907 } 2908 } 2909 } 2910 } 2911 } 2912 FREE_C_HEAP_ARRAY(unsigned long, cpu_map); 2913 } 2914 2915 int os::Linux::get_node_by_cpu(int cpu_id) { 2916 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2917 return cpu_to_node()->at(cpu_id); 2918 } 2919 return -1; 2920 } 2921 2922 GrowableArray<int>* os::Linux::_cpu_to_node; 2923 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2924 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2925 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2926 os::Linux::numa_available_func_t os::Linux::_numa_available; 2927 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2928 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2929 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy; 2930 unsigned long* os::Linux::_numa_all_nodes; 2931 2932 bool os::pd_uncommit_memory(char* addr, size_t size) { 2933 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE, 2934 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0); 2935 return res != (uintptr_t) MAP_FAILED; 2936 } 2937 2938 static address get_stack_commited_bottom(address bottom, size_t size) { 2939 address nbot = bottom; 2940 address ntop = bottom + size; 2941 2942 size_t page_sz = os::vm_page_size(); 2943 unsigned pages = size / page_sz; 2944 2945 unsigned char vec[1]; 2946 unsigned imin = 1, imax = pages + 1, imid; 2947 int mincore_return_value = 0; 2948 2949 assert(imin <= imax, "Unexpected page size"); 2950 2951 while (imin < imax) { 2952 imid = (imax + imin) / 2; 2953 nbot = ntop - (imid * page_sz); 2954 2955 // Use a trick with mincore to check whether the page is mapped or not. 2956 // mincore sets vec to 1 if page resides in memory and to 0 if page 2957 // is swapped output but if page we are asking for is unmapped 2958 // it returns -1,ENOMEM 2959 mincore_return_value = mincore(nbot, page_sz, vec); 2960 2961 if (mincore_return_value == -1) { 2962 // Page is not mapped go up 2963 // to find first mapped page 2964 if (errno != EAGAIN) { 2965 assert(errno == ENOMEM, "Unexpected mincore errno"); 2966 imax = imid; 2967 } 2968 } else { 2969 // Page is mapped go down 2970 // to find first not mapped page 2971 imin = imid + 1; 2972 } 2973 } 2974 2975 nbot = nbot + page_sz; 2976 2977 // Adjust stack bottom one page up if last checked page is not mapped 2978 if (mincore_return_value == -1) { 2979 nbot = nbot + page_sz; 2980 } 2981 2982 return nbot; 2983 } 2984 2985 2986 // Linux uses a growable mapping for the stack, and if the mapping for 2987 // the stack guard pages is not removed when we detach a thread the 2988 // stack cannot grow beyond the pages where the stack guard was 2989 // mapped. If at some point later in the process the stack expands to 2990 // that point, the Linux kernel cannot expand the stack any further 2991 // because the guard pages are in the way, and a segfault occurs. 2992 // 2993 // However, it's essential not to split the stack region by unmapping 2994 // a region (leaving a hole) that's already part of the stack mapping, 2995 // so if the stack mapping has already grown beyond the guard pages at 2996 // the time we create them, we have to truncate the stack mapping. 2997 // So, we need to know the extent of the stack mapping when 2998 // create_stack_guard_pages() is called. 2999 3000 // We only need this for stacks that are growable: at the time of 3001 // writing thread stacks don't use growable mappings (i.e. those 3002 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 3003 // only applies to the main thread. 3004 3005 // If the (growable) stack mapping already extends beyond the point 3006 // where we're going to put our guard pages, truncate the mapping at 3007 // that point by munmap()ping it. This ensures that when we later 3008 // munmap() the guard pages we don't leave a hole in the stack 3009 // mapping. This only affects the main/initial thread 3010 3011 bool os::pd_create_stack_guard_pages(char* addr, size_t size) { 3012 if (os::Linux::is_initial_thread()) { 3013 // As we manually grow stack up to bottom inside create_attached_thread(), 3014 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and 3015 // we don't need to do anything special. 3016 // Check it first, before calling heavy function. 3017 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom(); 3018 unsigned char vec[1]; 3019 3020 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) { 3021 // Fallback to slow path on all errors, including EAGAIN 3022 stack_extent = (uintptr_t) get_stack_commited_bottom( 3023 os::Linux::initial_thread_stack_bottom(), 3024 (size_t)addr - stack_extent); 3025 } 3026 3027 if (stack_extent < (uintptr_t)addr) { 3028 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent)); 3029 } 3030 } 3031 3032 return os::commit_memory(addr, size, !ExecMem); 3033 } 3034 3035 // If this is a growable mapping, remove the guard pages entirely by 3036 // munmap()ping them. If not, just call uncommit_memory(). This only 3037 // affects the main/initial thread, but guard against future OS changes 3038 // It's safe to always unmap guard pages for initial thread because we 3039 // always place it right after end of the mapped region 3040 3041 bool os::remove_stack_guard_pages(char* addr, size_t size) { 3042 uintptr_t stack_extent, stack_base; 3043 3044 if (os::Linux::is_initial_thread()) { 3045 return ::munmap(addr, size) == 0; 3046 } 3047 3048 return os::uncommit_memory(addr, size); 3049 } 3050 3051 static address _highest_vm_reserved_address = NULL; 3052 3053 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 3054 // at 'requested_addr'. If there are existing memory mappings at the same 3055 // location, however, they will be overwritten. If 'fixed' is false, 3056 // 'requested_addr' is only treated as a hint, the return value may or 3057 // may not start from the requested address. Unlike Linux mmap(), this 3058 // function returns NULL to indicate failure. 3059 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 3060 char * addr; 3061 int flags; 3062 3063 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 3064 if (fixed) { 3065 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 3066 flags |= MAP_FIXED; 3067 } 3068 3069 // Map reserved/uncommitted pages PROT_NONE so we fail early if we 3070 // touch an uncommitted page. Otherwise, the read/write might 3071 // succeed if we have enough swap space to back the physical page. 3072 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, 3073 flags, -1, 0); 3074 3075 if (addr != MAP_FAILED) { 3076 // anon_mmap() should only get called during VM initialization, 3077 // don't need lock (actually we can skip locking even it can be called 3078 // from multiple threads, because _highest_vm_reserved_address is just a 3079 // hint about the upper limit of non-stack memory regions.) 3080 if ((address)addr + bytes > _highest_vm_reserved_address) { 3081 _highest_vm_reserved_address = (address)addr + bytes; 3082 } 3083 } 3084 3085 return addr == MAP_FAILED ? NULL : addr; 3086 } 3087 3088 // Don't update _highest_vm_reserved_address, because there might be memory 3089 // regions above addr + size. If so, releasing a memory region only creates 3090 // a hole in the address space, it doesn't help prevent heap-stack collision. 3091 // 3092 static int anon_munmap(char * addr, size_t size) { 3093 return ::munmap(addr, size) == 0; 3094 } 3095 3096 char* os::pd_reserve_memory(size_t bytes, char* requested_addr, 3097 size_t alignment_hint) { 3098 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 3099 } 3100 3101 bool os::pd_release_memory(char* addr, size_t size) { 3102 return anon_munmap(addr, size); 3103 } 3104 3105 static address highest_vm_reserved_address() { 3106 return _highest_vm_reserved_address; 3107 } 3108 3109 static bool linux_mprotect(char* addr, size_t size, int prot) { 3110 // Linux wants the mprotect address argument to be page aligned. 3111 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 3112 3113 // According to SUSv3, mprotect() should only be used with mappings 3114 // established by mmap(), and mmap() always maps whole pages. Unaligned 3115 // 'addr' likely indicates problem in the VM (e.g. trying to change 3116 // protection of malloc'ed or statically allocated memory). Check the 3117 // caller if you hit this assert. 3118 assert(addr == bottom, "sanity check"); 3119 3120 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 3121 return ::mprotect(bottom, size, prot) == 0; 3122 } 3123 3124 // Set protections specified 3125 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 3126 bool is_committed) { 3127 unsigned int p = 0; 3128 switch (prot) { 3129 case MEM_PROT_NONE: p = PROT_NONE; break; 3130 case MEM_PROT_READ: p = PROT_READ; break; 3131 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 3132 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 3133 default: 3134 ShouldNotReachHere(); 3135 } 3136 // is_committed is unused. 3137 return linux_mprotect(addr, bytes, p); 3138 } 3139 3140 bool os::guard_memory(char* addr, size_t size) { 3141 return linux_mprotect(addr, size, PROT_NONE); 3142 } 3143 3144 bool os::unguard_memory(char* addr, size_t size) { 3145 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 3146 } 3147 3148 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, 3149 size_t page_size) { 3150 bool result = false; 3151 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 3152 MAP_ANONYMOUS|MAP_PRIVATE, 3153 -1, 0); 3154 if (p != MAP_FAILED) { 3155 void *aligned_p = align_ptr_up(p, page_size); 3156 3157 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0; 3158 3159 munmap(p, page_size * 2); 3160 } 3161 3162 if (warn && !result) { 3163 warning("TransparentHugePages is not supported by the operating system."); 3164 } 3165 3166 return result; 3167 } 3168 3169 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) { 3170 bool result = false; 3171 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE, 3172 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB, 3173 -1, 0); 3174 3175 if (p != MAP_FAILED) { 3176 // We don't know if this really is a huge page or not. 3177 FILE *fp = fopen("/proc/self/maps", "r"); 3178 if (fp) { 3179 while (!feof(fp)) { 3180 char chars[257]; 3181 long x = 0; 3182 if (fgets(chars, sizeof(chars), fp)) { 3183 if (sscanf(chars, "%lx-%*x", &x) == 1 3184 && x == (long)p) { 3185 if (strstr (chars, "hugepage")) { 3186 result = true; 3187 break; 3188 } 3189 } 3190 } 3191 } 3192 fclose(fp); 3193 } 3194 munmap(p, page_size); 3195 } 3196 3197 if (warn && !result) { 3198 warning("HugeTLBFS is not supported by the operating system."); 3199 } 3200 3201 return result; 3202 } 3203 3204 // Set the coredump_filter bits to include largepages in core dump (bit 6) 3205 // 3206 // From the coredump_filter documentation: 3207 // 3208 // - (bit 0) anonymous private memory 3209 // - (bit 1) anonymous shared memory 3210 // - (bit 2) file-backed private memory 3211 // - (bit 3) file-backed shared memory 3212 // - (bit 4) ELF header pages in file-backed private memory areas (it is 3213 // effective only if the bit 2 is cleared) 3214 // - (bit 5) hugetlb private memory 3215 // - (bit 6) hugetlb shared memory 3216 // 3217 static void set_coredump_filter(void) { 3218 FILE *f; 3219 long cdm; 3220 3221 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) { 3222 return; 3223 } 3224 3225 if (fscanf(f, "%lx", &cdm) != 1) { 3226 fclose(f); 3227 return; 3228 } 3229 3230 rewind(f); 3231 3232 if ((cdm & LARGEPAGES_BIT) == 0) { 3233 cdm |= LARGEPAGES_BIT; 3234 fprintf(f, "%#lx", cdm); 3235 } 3236 3237 fclose(f); 3238 } 3239 3240 // Large page support 3241 3242 static size_t _large_page_size = 0; 3243 3244 size_t os::Linux::find_large_page_size() { 3245 size_t large_page_size = 0; 3246 3247 // large_page_size on Linux is used to round up heap size. x86 uses either 3248 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 3249 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 3250 // page as large as 256M. 3251 // 3252 // Here we try to figure out page size by parsing /proc/meminfo and looking 3253 // for a line with the following format: 3254 // Hugepagesize: 2048 kB 3255 // 3256 // If we can't determine the value (e.g. /proc is not mounted, or the text 3257 // format has been changed), we'll use the largest page size supported by 3258 // the processor. 3259 3260 #ifndef ZERO 3261 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M) 3262 ARM32_ONLY(2 * M) PPC_ONLY(4 * M) AARCH64_ONLY(2 * M); 3263 #endif // ZERO 3264 3265 FILE *fp = fopen("/proc/meminfo", "r"); 3266 if (fp) { 3267 while (!feof(fp)) { 3268 int x = 0; 3269 char buf[16]; 3270 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 3271 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 3272 large_page_size = x * K; 3273 break; 3274 } 3275 } else { 3276 // skip to next line 3277 for (;;) { 3278 int ch = fgetc(fp); 3279 if (ch == EOF || ch == (int)'\n') break; 3280 } 3281 } 3282 } 3283 fclose(fp); 3284 } 3285 3286 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) { 3287 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is " 3288 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size), 3289 proper_unit_for_byte_size(large_page_size)); 3290 } 3291 3292 return large_page_size; 3293 } 3294 3295 size_t os::Linux::setup_large_page_size() { 3296 _large_page_size = Linux::find_large_page_size(); 3297 const size_t default_page_size = (size_t)Linux::page_size(); 3298 if (_large_page_size > default_page_size) { 3299 _page_sizes[0] = _large_page_size; 3300 _page_sizes[1] = default_page_size; 3301 _page_sizes[2] = 0; 3302 } 3303 3304 return _large_page_size; 3305 } 3306 3307 bool os::Linux::setup_large_page_type(size_t page_size) { 3308 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && 3309 FLAG_IS_DEFAULT(UseSHM) && 3310 FLAG_IS_DEFAULT(UseTransparentHugePages)) { 3311 3312 // The type of large pages has not been specified by the user. 3313 3314 // Try UseHugeTLBFS and then UseSHM. 3315 UseHugeTLBFS = UseSHM = true; 3316 3317 // Don't try UseTransparentHugePages since there are known 3318 // performance issues with it turned on. This might change in the future. 3319 UseTransparentHugePages = false; 3320 } 3321 3322 if (UseTransparentHugePages) { 3323 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages); 3324 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) { 3325 UseHugeTLBFS = false; 3326 UseSHM = false; 3327 return true; 3328 } 3329 UseTransparentHugePages = false; 3330 } 3331 3332 if (UseHugeTLBFS) { 3333 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS); 3334 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) { 3335 UseSHM = false; 3336 return true; 3337 } 3338 UseHugeTLBFS = false; 3339 } 3340 3341 return UseSHM; 3342 } 3343 3344 void os::large_page_init() { 3345 if (!UseLargePages && 3346 !UseTransparentHugePages && 3347 !UseHugeTLBFS && 3348 !UseSHM) { 3349 // Not using large pages. 3350 return; 3351 } 3352 3353 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) { 3354 // The user explicitly turned off large pages. 3355 // Ignore the rest of the large pages flags. 3356 UseTransparentHugePages = false; 3357 UseHugeTLBFS = false; 3358 UseSHM = false; 3359 return; 3360 } 3361 3362 size_t large_page_size = Linux::setup_large_page_size(); 3363 UseLargePages = Linux::setup_large_page_type(large_page_size); 3364 3365 set_coredump_filter(); 3366 } 3367 3368 #ifndef SHM_HUGETLB 3369 #define SHM_HUGETLB 04000 3370 #endif 3371 3372 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, 3373 char* req_addr, bool exec) { 3374 // "exec" is passed in but not used. Creating the shared image for 3375 // the code cache doesn't have an SHM_X executable permission to check. 3376 assert(UseLargePages && UseSHM, "only for SHM large pages"); 3377 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3378 3379 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) { 3380 return NULL; // Fallback to small pages. 3381 } 3382 3383 key_t key = IPC_PRIVATE; 3384 char *addr; 3385 3386 bool warn_on_failure = UseLargePages && 3387 (!FLAG_IS_DEFAULT(UseLargePages) || 3388 !FLAG_IS_DEFAULT(UseSHM) || 3389 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3390 char msg[128]; 3391 3392 // Create a large shared memory region to attach to based on size. 3393 // Currently, size is the total size of the heap 3394 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 3395 if (shmid == -1) { 3396 // Possible reasons for shmget failure: 3397 // 1. shmmax is too small for Java heap. 3398 // > check shmmax value: cat /proc/sys/kernel/shmmax 3399 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 3400 // 2. not enough large page memory. 3401 // > check available large pages: cat /proc/meminfo 3402 // > increase amount of large pages: 3403 // echo new_value > /proc/sys/vm/nr_hugepages 3404 // Note 1: different Linux may use different name for this property, 3405 // e.g. on Redhat AS-3 it is "hugetlb_pool". 3406 // Note 2: it's possible there's enough physical memory available but 3407 // they are so fragmented after a long run that they can't 3408 // coalesce into large pages. Try to reserve large pages when 3409 // the system is still "fresh". 3410 if (warn_on_failure) { 3411 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 3412 warning("%s", msg); 3413 } 3414 return NULL; 3415 } 3416 3417 // attach to the region 3418 addr = (char*)shmat(shmid, req_addr, 0); 3419 int err = errno; 3420 3421 // Remove shmid. If shmat() is successful, the actual shared memory segment 3422 // will be deleted when it's detached by shmdt() or when the process 3423 // terminates. If shmat() is not successful this will remove the shared 3424 // segment immediately. 3425 shmctl(shmid, IPC_RMID, NULL); 3426 3427 if ((intptr_t)addr == -1) { 3428 if (warn_on_failure) { 3429 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 3430 warning("%s", msg); 3431 } 3432 return NULL; 3433 } 3434 3435 return addr; 3436 } 3437 3438 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, 3439 int error) { 3440 assert(error == ENOMEM, "Only expect to fail if no memory is available"); 3441 3442 bool warn_on_failure = UseLargePages && 3443 (!FLAG_IS_DEFAULT(UseLargePages) || 3444 !FLAG_IS_DEFAULT(UseHugeTLBFS) || 3445 !FLAG_IS_DEFAULT(LargePageSizeInBytes)); 3446 3447 if (warn_on_failure) { 3448 char msg[128]; 3449 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: " 3450 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error); 3451 warning("%s", msg); 3452 } 3453 } 3454 3455 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, 3456 char* req_addr, 3457 bool exec) { 3458 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3459 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size"); 3460 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address"); 3461 3462 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3463 char* addr = (char*)::mmap(req_addr, bytes, prot, 3464 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, 3465 -1, 0); 3466 3467 if (addr == MAP_FAILED) { 3468 warn_on_large_pages_failure(req_addr, bytes, errno); 3469 return NULL; 3470 } 3471 3472 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be"); 3473 3474 return addr; 3475 } 3476 3477 // Helper for os::Linux::reserve_memory_special_huge_tlbfs_mixed(). 3478 // Allocate (using mmap, NO_RESERVE, with small pages) at either a given request address 3479 // (req_addr != NULL) or with a given alignment. 3480 // - bytes shall be a multiple of alignment. 3481 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment. 3482 // - alignment sets the alignment at which memory shall be allocated. 3483 // It must be a multiple of allocation granularity. 3484 // Returns address of memory or NULL. If req_addr was not NULL, will only return 3485 // req_addr or NULL. 3486 static char* anon_mmap_aligned(size_t bytes, size_t alignment, char* req_addr) { 3487 3488 size_t extra_size = bytes; 3489 if (req_addr == NULL && alignment > 0) { 3490 extra_size += alignment; 3491 } 3492 3493 char* start = (char*) ::mmap(req_addr, extra_size, PROT_NONE, 3494 MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, 3495 -1, 0); 3496 if (start == MAP_FAILED) { 3497 start = NULL; 3498 } else { 3499 if (req_addr != NULL) { 3500 if (start != req_addr) { 3501 ::munmap(start, extra_size); 3502 start = NULL; 3503 } 3504 } else { 3505 char* const start_aligned = (char*) align_ptr_up(start, alignment); 3506 char* const end_aligned = start_aligned + bytes; 3507 char* const end = start + extra_size; 3508 if (start_aligned > start) { 3509 ::munmap(start, start_aligned - start); 3510 } 3511 if (end_aligned < end) { 3512 ::munmap(end_aligned, end - end_aligned); 3513 } 3514 start = start_aligned; 3515 } 3516 } 3517 return start; 3518 3519 } 3520 3521 // Reserve memory using mmap(MAP_HUGETLB). 3522 // - bytes shall be a multiple of alignment. 3523 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment. 3524 // - alignment sets the alignment at which memory shall be allocated. 3525 // It must be a multiple of allocation granularity. 3526 // Returns address of memory or NULL. If req_addr was not NULL, will only return 3527 // req_addr or NULL. 3528 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, 3529 size_t alignment, 3530 char* req_addr, 3531 bool exec) { 3532 size_t large_page_size = os::large_page_size(); 3533 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes"); 3534 3535 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3536 assert(is_size_aligned(bytes, alignment), "Must be"); 3537 3538 // First reserve - but not commit - the address range in small pages. 3539 char* const start = anon_mmap_aligned(bytes, alignment, req_addr); 3540 3541 if (start == NULL) { 3542 return NULL; 3543 } 3544 3545 assert(is_ptr_aligned(start, alignment), "Must be"); 3546 3547 char* end = start + bytes; 3548 3549 // Find the regions of the allocated chunk that can be promoted to large pages. 3550 char* lp_start = (char*)align_ptr_up(start, large_page_size); 3551 char* lp_end = (char*)align_ptr_down(end, large_page_size); 3552 3553 size_t lp_bytes = lp_end - lp_start; 3554 3555 assert(is_size_aligned(lp_bytes, large_page_size), "Must be"); 3556 3557 if (lp_bytes == 0) { 3558 // The mapped region doesn't even span the start and the end of a large page. 3559 // Fall back to allocate a non-special area. 3560 ::munmap(start, end - start); 3561 return NULL; 3562 } 3563 3564 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 3565 3566 void* result; 3567 3568 // Commit small-paged leading area. 3569 if (start != lp_start) { 3570 result = ::mmap(start, lp_start - start, prot, 3571 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3572 -1, 0); 3573 if (result == MAP_FAILED) { 3574 ::munmap(lp_start, end - lp_start); 3575 return NULL; 3576 } 3577 } 3578 3579 // Commit large-paged area. 3580 result = ::mmap(lp_start, lp_bytes, prot, 3581 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, 3582 -1, 0); 3583 if (result == MAP_FAILED) { 3584 warn_on_large_pages_failure(lp_start, lp_bytes, errno); 3585 // If the mmap above fails, the large pages region will be unmapped and we 3586 // have regions before and after with small pages. Release these regions. 3587 // 3588 // | mapped | unmapped | mapped | 3589 // ^ ^ ^ ^ 3590 // start lp_start lp_end end 3591 // 3592 ::munmap(start, lp_start - start); 3593 ::munmap(lp_end, end - lp_end); 3594 return NULL; 3595 } 3596 3597 // Commit small-paged trailing area. 3598 if (lp_end != end) { 3599 result = ::mmap(lp_end, end - lp_end, prot, 3600 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 3601 -1, 0); 3602 if (result == MAP_FAILED) { 3603 ::munmap(start, lp_end - start); 3604 return NULL; 3605 } 3606 } 3607 3608 return start; 3609 } 3610 3611 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, 3612 size_t alignment, 3613 char* req_addr, 3614 bool exec) { 3615 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages"); 3616 assert(is_ptr_aligned(req_addr, alignment), "Must be"); 3617 assert(is_size_aligned(alignment, os::vm_allocation_granularity()), "Must be"); 3618 assert(is_power_of_2(os::large_page_size()), "Must be"); 3619 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes"); 3620 3621 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) { 3622 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec); 3623 } else { 3624 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec); 3625 } 3626 } 3627 3628 char* os::reserve_memory_special(size_t bytes, size_t alignment, 3629 char* req_addr, bool exec) { 3630 assert(UseLargePages, "only for large pages"); 3631 3632 char* addr; 3633 if (UseSHM) { 3634 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec); 3635 } else { 3636 assert(UseHugeTLBFS, "must be"); 3637 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec); 3638 } 3639 3640 if (addr != NULL) { 3641 if (UseNUMAInterleaving) { 3642 numa_make_global(addr, bytes); 3643 } 3644 3645 // The memory is committed 3646 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC); 3647 } 3648 3649 return addr; 3650 } 3651 3652 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) { 3653 // detaching the SHM segment will also delete it, see reserve_memory_special_shm() 3654 return shmdt(base) == 0; 3655 } 3656 3657 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) { 3658 return pd_release_memory(base, bytes); 3659 } 3660 3661 bool os::release_memory_special(char* base, size_t bytes) { 3662 bool res; 3663 if (MemTracker::tracking_level() > NMT_minimal) { 3664 Tracker tkr = MemTracker::get_virtual_memory_release_tracker(); 3665 res = os::Linux::release_memory_special_impl(base, bytes); 3666 if (res) { 3667 tkr.record((address)base, bytes); 3668 } 3669 3670 } else { 3671 res = os::Linux::release_memory_special_impl(base, bytes); 3672 } 3673 return res; 3674 } 3675 3676 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) { 3677 assert(UseLargePages, "only for large pages"); 3678 bool res; 3679 3680 if (UseSHM) { 3681 res = os::Linux::release_memory_special_shm(base, bytes); 3682 } else { 3683 assert(UseHugeTLBFS, "must be"); 3684 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes); 3685 } 3686 return res; 3687 } 3688 3689 size_t os::large_page_size() { 3690 return _large_page_size; 3691 } 3692 3693 // With SysV SHM the entire memory region must be allocated as shared 3694 // memory. 3695 // HugeTLBFS allows application to commit large page memory on demand. 3696 // However, when committing memory with HugeTLBFS fails, the region 3697 // that was supposed to be committed will lose the old reservation 3698 // and allow other threads to steal that memory region. Because of this 3699 // behavior we can't commit HugeTLBFS memory. 3700 bool os::can_commit_large_page_memory() { 3701 return UseTransparentHugePages; 3702 } 3703 3704 bool os::can_execute_large_page_memory() { 3705 return UseTransparentHugePages || UseHugeTLBFS; 3706 } 3707 3708 // Reserve memory at an arbitrary address, only if that area is 3709 // available (and not reserved for something else). 3710 3711 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 3712 const int max_tries = 10; 3713 char* base[max_tries]; 3714 size_t size[max_tries]; 3715 const size_t gap = 0x000000; 3716 3717 // Assert only that the size is a multiple of the page size, since 3718 // that's all that mmap requires, and since that's all we really know 3719 // about at this low abstraction level. If we need higher alignment, 3720 // we can either pass an alignment to this method or verify alignment 3721 // in one of the methods further up the call chain. See bug 5044738. 3722 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 3723 3724 // Repeatedly allocate blocks until the block is allocated at the 3725 // right spot. Give up after max_tries. Note that reserve_memory() will 3726 // automatically update _highest_vm_reserved_address if the call is 3727 // successful. The variable tracks the highest memory address every reserved 3728 // by JVM. It is used to detect heap-stack collision if running with 3729 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 3730 // space than needed, it could confuse the collision detecting code. To 3731 // solve the problem, save current _highest_vm_reserved_address and 3732 // calculate the correct value before return. 3733 address old_highest = _highest_vm_reserved_address; 3734 3735 // Linux mmap allows caller to pass an address as hint; give it a try first, 3736 // if kernel honors the hint then we can return immediately. 3737 char * addr = anon_mmap(requested_addr, bytes, false); 3738 if (addr == requested_addr) { 3739 return requested_addr; 3740 } 3741 3742 if (addr != NULL) { 3743 // mmap() is successful but it fails to reserve at the requested address 3744 anon_munmap(addr, bytes); 3745 } 3746 3747 int i; 3748 for (i = 0; i < max_tries; ++i) { 3749 base[i] = reserve_memory(bytes); 3750 3751 if (base[i] != NULL) { 3752 // Is this the block we wanted? 3753 if (base[i] == requested_addr) { 3754 size[i] = bytes; 3755 break; 3756 } 3757 3758 // Does this overlap the block we wanted? Give back the overlapped 3759 // parts and try again. 3760 3761 ptrdiff_t top_overlap = requested_addr + (bytes + gap) - base[i]; 3762 if (top_overlap >= 0 && (size_t)top_overlap < bytes) { 3763 unmap_memory(base[i], top_overlap); 3764 base[i] += top_overlap; 3765 size[i] = bytes - top_overlap; 3766 } else { 3767 ptrdiff_t bottom_overlap = base[i] + bytes - requested_addr; 3768 if (bottom_overlap >= 0 && (size_t)bottom_overlap < bytes) { 3769 unmap_memory(requested_addr, bottom_overlap); 3770 size[i] = bytes - bottom_overlap; 3771 } else { 3772 size[i] = bytes; 3773 } 3774 } 3775 } 3776 } 3777 3778 // Give back the unused reserved pieces. 3779 3780 for (int j = 0; j < i; ++j) { 3781 if (base[j] != NULL) { 3782 unmap_memory(base[j], size[j]); 3783 } 3784 } 3785 3786 if (i < max_tries) { 3787 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 3788 return requested_addr; 3789 } else { 3790 _highest_vm_reserved_address = old_highest; 3791 return NULL; 3792 } 3793 } 3794 3795 size_t os::read(int fd, void *buf, unsigned int nBytes) { 3796 return ::read(fd, buf, nBytes); 3797 } 3798 3799 size_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) { 3800 return ::pread(fd, buf, nBytes, offset); 3801 } 3802 3803 // Short sleep, direct OS call. 3804 // 3805 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee 3806 // sched_yield(2) will actually give up the CPU: 3807 // 3808 // * Alone on this pariticular CPU, keeps running. 3809 // * Before the introduction of "skip_buddy" with "compat_yield" disabled 3810 // (pre 2.6.39). 3811 // 3812 // So calling this with 0 is an alternative. 3813 // 3814 void os::naked_short_sleep(jlong ms) { 3815 struct timespec req; 3816 3817 assert(ms < 1000, "Un-interruptable sleep, short time use only"); 3818 req.tv_sec = 0; 3819 if (ms > 0) { 3820 req.tv_nsec = (ms % 1000) * 1000000; 3821 } else { 3822 req.tv_nsec = 1; 3823 } 3824 3825 nanosleep(&req, NULL); 3826 3827 return; 3828 } 3829 3830 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3831 void os::infinite_sleep() { 3832 while (true) { // sleep forever ... 3833 ::sleep(100); // ... 100 seconds at a time 3834 } 3835 } 3836 3837 // Used to convert frequent JVM_Yield() to nops 3838 bool os::dont_yield() { 3839 return DontYieldALot; 3840 } 3841 3842 void os::naked_yield() { 3843 sched_yield(); 3844 } 3845 3846 //////////////////////////////////////////////////////////////////////////////// 3847 // thread priority support 3848 3849 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3850 // only supports dynamic priority, static priority must be zero. For real-time 3851 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3852 // However, for large multi-threaded applications, SCHED_RR is not only slower 3853 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3854 // of 5 runs - Sep 2005). 3855 // 3856 // The following code actually changes the niceness of kernel-thread/LWP. It 3857 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3858 // not the entire user process, and user level threads are 1:1 mapped to kernel 3859 // threads. It has always been the case, but could change in the future. For 3860 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3861 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3862 3863 int os::java_to_os_priority[CriticalPriority + 1] = { 3864 19, // 0 Entry should never be used 3865 3866 4, // 1 MinPriority 3867 3, // 2 3868 2, // 3 3869 3870 1, // 4 3871 0, // 5 NormPriority 3872 -1, // 6 3873 3874 -2, // 7 3875 -3, // 8 3876 -4, // 9 NearMaxPriority 3877 3878 -5, // 10 MaxPriority 3879 3880 -5 // 11 CriticalPriority 3881 }; 3882 3883 static int prio_init() { 3884 if (ThreadPriorityPolicy == 1) { 3885 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3886 // if effective uid is not root. Perhaps, a more elegant way of doing 3887 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3888 if (geteuid() != 0) { 3889 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3890 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3891 } 3892 ThreadPriorityPolicy = 0; 3893 } 3894 } 3895 if (UseCriticalJavaThreadPriority) { 3896 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority]; 3897 } 3898 return 0; 3899 } 3900 3901 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3902 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK; 3903 3904 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3905 return (ret == 0) ? OS_OK : OS_ERR; 3906 } 3907 3908 OSReturn os::get_native_priority(const Thread* const thread, 3909 int *priority_ptr) { 3910 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) { 3911 *priority_ptr = java_to_os_priority[NormPriority]; 3912 return OS_OK; 3913 } 3914 3915 errno = 0; 3916 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3917 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3918 } 3919 3920 // Hint to the underlying OS that a task switch would not be good. 3921 // Void return because it's a hint and can fail. 3922 void os::hint_no_preempt() {} 3923 3924 //////////////////////////////////////////////////////////////////////////////// 3925 // suspend/resume support 3926 3927 // the low-level signal-based suspend/resume support is a remnant from the 3928 // old VM-suspension that used to be for java-suspension, safepoints etc, 3929 // within hotspot. Now there is a single use-case for this: 3930 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3931 // that runs in the watcher thread. 3932 // The remaining code is greatly simplified from the more general suspension 3933 // code that used to be used. 3934 // 3935 // The protocol is quite simple: 3936 // - suspend: 3937 // - sends a signal to the target thread 3938 // - polls the suspend state of the osthread using a yield loop 3939 // - target thread signal handler (SR_handler) sets suspend state 3940 // and blocks in sigsuspend until continued 3941 // - resume: 3942 // - sets target osthread state to continue 3943 // - sends signal to end the sigsuspend loop in the SR_handler 3944 // 3945 // Note that the SR_lock plays no role in this suspend/resume protocol. 3946 3947 static void resume_clear_context(OSThread *osthread) { 3948 osthread->set_ucontext(NULL); 3949 osthread->set_siginfo(NULL); 3950 } 3951 3952 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, 3953 ucontext_t* context) { 3954 osthread->set_ucontext(context); 3955 osthread->set_siginfo(siginfo); 3956 } 3957 3958 // Handler function invoked when a thread's execution is suspended or 3959 // resumed. We have to be careful that only async-safe functions are 3960 // called here (Note: most pthread functions are not async safe and 3961 // should be avoided.) 3962 // 3963 // Note: sigwait() is a more natural fit than sigsuspend() from an 3964 // interface point of view, but sigwait() prevents the signal hander 3965 // from being run. libpthread would get very confused by not having 3966 // its signal handlers run and prevents sigwait()'s use with the 3967 // mutex granting granting signal. 3968 // 3969 // Currently only ever called on the VMThread and JavaThreads (PC sampling) 3970 // 3971 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3972 // Save and restore errno to avoid confusing native code with EINTR 3973 // after sigsuspend. 3974 int old_errno = errno; 3975 3976 Thread* thread = Thread::current(); 3977 OSThread* osthread = thread->osthread(); 3978 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread"); 3979 3980 os::SuspendResume::State current = osthread->sr.state(); 3981 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) { 3982 suspend_save_context(osthread, siginfo, context); 3983 3984 // attempt to switch the state, we assume we had a SUSPEND_REQUEST 3985 os::SuspendResume::State state = osthread->sr.suspended(); 3986 if (state == os::SuspendResume::SR_SUSPENDED) { 3987 sigset_t suspend_set; // signals for sigsuspend() 3988 3989 // get current set of blocked signals and unblock resume signal 3990 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3991 sigdelset(&suspend_set, SR_signum); 3992 3993 sr_semaphore.signal(); 3994 // wait here until we are resumed 3995 while (1) { 3996 sigsuspend(&suspend_set); 3997 3998 os::SuspendResume::State result = osthread->sr.running(); 3999 if (result == os::SuspendResume::SR_RUNNING) { 4000 sr_semaphore.signal(); 4001 break; 4002 } 4003 } 4004 4005 } else if (state == os::SuspendResume::SR_RUNNING) { 4006 // request was cancelled, continue 4007 } else { 4008 ShouldNotReachHere(); 4009 } 4010 4011 resume_clear_context(osthread); 4012 } else if (current == os::SuspendResume::SR_RUNNING) { 4013 // request was cancelled, continue 4014 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) { 4015 // ignore 4016 } else { 4017 // ignore 4018 } 4019 4020 errno = old_errno; 4021 } 4022 4023 4024 static int SR_initialize() { 4025 struct sigaction act; 4026 char *s; 4027 // Get signal number to use for suspend/resume 4028 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 4029 int sig = ::strtol(s, 0, 10); 4030 if (sig > 0 || sig < _NSIG) { 4031 SR_signum = sig; 4032 } 4033 } 4034 4035 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 4036 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 4037 4038 sigemptyset(&SR_sigset); 4039 sigaddset(&SR_sigset, SR_signum); 4040 4041 // Set up signal handler for suspend/resume 4042 act.sa_flags = SA_RESTART|SA_SIGINFO; 4043 act.sa_handler = (void (*)(int)) SR_handler; 4044 4045 // SR_signum is blocked by default. 4046 // 4528190 - We also need to block pthread restart signal (32 on all 4047 // supported Linux platforms). Note that LinuxThreads need to block 4048 // this signal for all threads to work properly. So we don't have 4049 // to use hard-coded signal number when setting up the mask. 4050 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 4051 4052 if (sigaction(SR_signum, &act, 0) == -1) { 4053 return -1; 4054 } 4055 4056 // Save signal flag 4057 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 4058 return 0; 4059 } 4060 4061 static int sr_notify(OSThread* osthread) { 4062 int status = pthread_kill(osthread->pthread_id(), SR_signum); 4063 assert_status(status == 0, status, "pthread_kill"); 4064 return status; 4065 } 4066 4067 // "Randomly" selected value for how long we want to spin 4068 // before bailing out on suspending a thread, also how often 4069 // we send a signal to a thread we want to resume 4070 static const int RANDOMLY_LARGE_INTEGER = 1000000; 4071 static const int RANDOMLY_LARGE_INTEGER2 = 100; 4072 4073 // returns true on success and false on error - really an error is fatal 4074 // but this seems the normal response to library errors 4075 static bool do_suspend(OSThread* osthread) { 4076 assert(osthread->sr.is_running(), "thread should be running"); 4077 assert(!sr_semaphore.trywait(), "semaphore has invalid state"); 4078 4079 // mark as suspended and send signal 4080 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) { 4081 // failed to switch, state wasn't running? 4082 ShouldNotReachHere(); 4083 return false; 4084 } 4085 4086 if (sr_notify(osthread) != 0) { 4087 ShouldNotReachHere(); 4088 } 4089 4090 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED 4091 while (true) { 4092 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4093 break; 4094 } else { 4095 // timeout 4096 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend(); 4097 if (cancelled == os::SuspendResume::SR_RUNNING) { 4098 return false; 4099 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) { 4100 // make sure that we consume the signal on the semaphore as well 4101 sr_semaphore.wait(); 4102 break; 4103 } else { 4104 ShouldNotReachHere(); 4105 return false; 4106 } 4107 } 4108 } 4109 4110 guarantee(osthread->sr.is_suspended(), "Must be suspended"); 4111 return true; 4112 } 4113 4114 static void do_resume(OSThread* osthread) { 4115 assert(osthread->sr.is_suspended(), "thread should be suspended"); 4116 assert(!sr_semaphore.trywait(), "invalid semaphore state"); 4117 4118 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) { 4119 // failed to switch to WAKEUP_REQUEST 4120 ShouldNotReachHere(); 4121 return; 4122 } 4123 4124 while (true) { 4125 if (sr_notify(osthread) == 0) { 4126 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) { 4127 if (osthread->sr.is_running()) { 4128 return; 4129 } 4130 } 4131 } else { 4132 ShouldNotReachHere(); 4133 } 4134 } 4135 4136 guarantee(osthread->sr.is_running(), "Must be running!"); 4137 } 4138 4139 /////////////////////////////////////////////////////////////////////////////////// 4140 // signal handling (except suspend/resume) 4141 4142 // This routine may be used by user applications as a "hook" to catch signals. 4143 // The user-defined signal handler must pass unrecognized signals to this 4144 // routine, and if it returns true (non-zero), then the signal handler must 4145 // return immediately. If the flag "abort_if_unrecognized" is true, then this 4146 // routine will never retun false (zero), but instead will execute a VM panic 4147 // routine kill the process. 4148 // 4149 // If this routine returns false, it is OK to call it again. This allows 4150 // the user-defined signal handler to perform checks either before or after 4151 // the VM performs its own checks. Naturally, the user code would be making 4152 // a serious error if it tried to handle an exception (such as a null check 4153 // or breakpoint) that the VM was generating for its own correct operation. 4154 // 4155 // This routine may recognize any of the following kinds of signals: 4156 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 4157 // It should be consulted by handlers for any of those signals. 4158 // 4159 // The caller of this routine must pass in the three arguments supplied 4160 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 4161 // field of the structure passed to sigaction(). This routine assumes that 4162 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 4163 // 4164 // Note that the VM will print warnings if it detects conflicting signal 4165 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 4166 // 4167 extern "C" JNIEXPORT int JVM_handle_linux_signal(int signo, 4168 siginfo_t* siginfo, 4169 void* ucontext, 4170 int abort_if_unrecognized); 4171 4172 void signalHandler(int sig, siginfo_t* info, void* uc) { 4173 assert(info != NULL && uc != NULL, "it must be old kernel"); 4174 int orig_errno = errno; // Preserve errno value over signal handler. 4175 JVM_handle_linux_signal(sig, info, uc, true); 4176 errno = orig_errno; 4177 } 4178 4179 4180 // This boolean allows users to forward their own non-matching signals 4181 // to JVM_handle_linux_signal, harmlessly. 4182 bool os::Linux::signal_handlers_are_installed = false; 4183 4184 // For signal-chaining 4185 struct sigaction os::Linux::sigact[MAXSIGNUM]; 4186 unsigned int os::Linux::sigs = 0; 4187 bool os::Linux::libjsig_is_loaded = false; 4188 typedef struct sigaction *(*get_signal_t)(int); 4189 get_signal_t os::Linux::get_signal_action = NULL; 4190 4191 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 4192 struct sigaction *actp = NULL; 4193 4194 if (libjsig_is_loaded) { 4195 // Retrieve the old signal handler from libjsig 4196 actp = (*get_signal_action)(sig); 4197 } 4198 if (actp == NULL) { 4199 // Retrieve the preinstalled signal handler from jvm 4200 actp = get_preinstalled_handler(sig); 4201 } 4202 4203 return actp; 4204 } 4205 4206 static bool call_chained_handler(struct sigaction *actp, int sig, 4207 siginfo_t *siginfo, void *context) { 4208 // Call the old signal handler 4209 if (actp->sa_handler == SIG_DFL) { 4210 // It's more reasonable to let jvm treat it as an unexpected exception 4211 // instead of taking the default action. 4212 return false; 4213 } else if (actp->sa_handler != SIG_IGN) { 4214 if ((actp->sa_flags & SA_NODEFER) == 0) { 4215 // automaticlly block the signal 4216 sigaddset(&(actp->sa_mask), sig); 4217 } 4218 4219 sa_handler_t hand; 4220 sa_sigaction_t sa; 4221 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 4222 // retrieve the chained handler 4223 if (siginfo_flag_set) { 4224 sa = actp->sa_sigaction; 4225 } else { 4226 hand = actp->sa_handler; 4227 } 4228 4229 if ((actp->sa_flags & SA_RESETHAND) != 0) { 4230 actp->sa_handler = SIG_DFL; 4231 } 4232 4233 // try to honor the signal mask 4234 sigset_t oset; 4235 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 4236 4237 // call into the chained handler 4238 if (siginfo_flag_set) { 4239 (*sa)(sig, siginfo, context); 4240 } else { 4241 (*hand)(sig); 4242 } 4243 4244 // restore the signal mask 4245 pthread_sigmask(SIG_SETMASK, &oset, 0); 4246 } 4247 // Tell jvm's signal handler the signal is taken care of. 4248 return true; 4249 } 4250 4251 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 4252 bool chained = false; 4253 // signal-chaining 4254 if (UseSignalChaining) { 4255 struct sigaction *actp = get_chained_signal_action(sig); 4256 if (actp != NULL) { 4257 chained = call_chained_handler(actp, sig, siginfo, context); 4258 } 4259 } 4260 return chained; 4261 } 4262 4263 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 4264 if ((((unsigned int)1 << sig) & sigs) != 0) { 4265 return &sigact[sig]; 4266 } 4267 return NULL; 4268 } 4269 4270 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 4271 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4272 sigact[sig] = oldAct; 4273 sigs |= (unsigned int)1 << sig; 4274 } 4275 4276 // for diagnostic 4277 int os::Linux::sigflags[MAXSIGNUM]; 4278 4279 int os::Linux::get_our_sigflags(int sig) { 4280 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4281 return sigflags[sig]; 4282 } 4283 4284 void os::Linux::set_our_sigflags(int sig, int flags) { 4285 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4286 sigflags[sig] = flags; 4287 } 4288 4289 void os::Linux::set_signal_handler(int sig, bool set_installed) { 4290 // Check for overwrite. 4291 struct sigaction oldAct; 4292 sigaction(sig, (struct sigaction*)NULL, &oldAct); 4293 4294 void* oldhand = oldAct.sa_sigaction 4295 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4296 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4297 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 4298 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 4299 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 4300 if (AllowUserSignalHandlers || !set_installed) { 4301 // Do not overwrite; user takes responsibility to forward to us. 4302 return; 4303 } else if (UseSignalChaining) { 4304 // save the old handler in jvm 4305 save_preinstalled_handler(sig, oldAct); 4306 // libjsig also interposes the sigaction() call below and saves the 4307 // old sigaction on it own. 4308 } else { 4309 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 4310 "%#lx for signal %d.", (long)oldhand, sig)); 4311 } 4312 } 4313 4314 struct sigaction sigAct; 4315 sigfillset(&(sigAct.sa_mask)); 4316 sigAct.sa_handler = SIG_DFL; 4317 if (!set_installed) { 4318 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4319 } else { 4320 sigAct.sa_sigaction = signalHandler; 4321 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 4322 } 4323 // Save flags, which are set by ours 4324 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 4325 sigflags[sig] = sigAct.sa_flags; 4326 4327 int ret = sigaction(sig, &sigAct, &oldAct); 4328 assert(ret == 0, "check"); 4329 4330 void* oldhand2 = oldAct.sa_sigaction 4331 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 4332 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 4333 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 4334 } 4335 4336 // install signal handlers for signals that HotSpot needs to 4337 // handle in order to support Java-level exception handling. 4338 4339 void os::Linux::install_signal_handlers() { 4340 if (!signal_handlers_are_installed) { 4341 signal_handlers_are_installed = true; 4342 4343 // signal-chaining 4344 typedef void (*signal_setting_t)(); 4345 signal_setting_t begin_signal_setting = NULL; 4346 signal_setting_t end_signal_setting = NULL; 4347 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4348 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 4349 if (begin_signal_setting != NULL) { 4350 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 4351 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 4352 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 4353 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 4354 libjsig_is_loaded = true; 4355 assert(UseSignalChaining, "should enable signal-chaining"); 4356 } 4357 if (libjsig_is_loaded) { 4358 // Tell libjsig jvm is setting signal handlers 4359 (*begin_signal_setting)(); 4360 } 4361 4362 set_signal_handler(SIGSEGV, true); 4363 set_signal_handler(SIGPIPE, true); 4364 set_signal_handler(SIGBUS, true); 4365 set_signal_handler(SIGILL, true); 4366 set_signal_handler(SIGFPE, true); 4367 #if defined(PPC64) 4368 set_signal_handler(SIGTRAP, true); 4369 #endif 4370 set_signal_handler(SIGXFSZ, true); 4371 4372 if (libjsig_is_loaded) { 4373 // Tell libjsig jvm finishes setting signal handlers 4374 (*end_signal_setting)(); 4375 } 4376 4377 // We don't activate signal checker if libjsig is in place, we trust ourselves 4378 // and if UserSignalHandler is installed all bets are off. 4379 // Log that signal checking is off only if -verbose:jni is specified. 4380 if (CheckJNICalls) { 4381 if (libjsig_is_loaded) { 4382 if (PrintJNIResolving) { 4383 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 4384 } 4385 check_signals = false; 4386 } 4387 if (AllowUserSignalHandlers) { 4388 if (PrintJNIResolving) { 4389 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 4390 } 4391 check_signals = false; 4392 } 4393 } 4394 } 4395 } 4396 4397 // This is the fastest way to get thread cpu time on Linux. 4398 // Returns cpu time (user+sys) for any thread, not only for current. 4399 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 4400 // It might work on 2.6.10+ with a special kernel/glibc patch. 4401 // For reference, please, see IEEE Std 1003.1-2004: 4402 // http://www.unix.org/single_unix_specification 4403 4404 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 4405 struct timespec tp; 4406 int rc = os::Linux::clock_gettime(clockid, &tp); 4407 assert(rc == 0, "clock_gettime is expected to return 0 code"); 4408 4409 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec; 4410 } 4411 4412 ///// 4413 // glibc on Linux platform uses non-documented flag 4414 // to indicate, that some special sort of signal 4415 // trampoline is used. 4416 // We will never set this flag, and we should 4417 // ignore this flag in our diagnostic 4418 #ifdef SIGNIFICANT_SIGNAL_MASK 4419 #undef SIGNIFICANT_SIGNAL_MASK 4420 #endif 4421 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 4422 4423 static const char* get_signal_handler_name(address handler, 4424 char* buf, int buflen) { 4425 int offset; 4426 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 4427 if (found) { 4428 // skip directory names 4429 const char *p1, *p2; 4430 p1 = buf; 4431 size_t len = strlen(os::file_separator()); 4432 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 4433 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 4434 } else { 4435 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 4436 } 4437 return buf; 4438 } 4439 4440 static void print_signal_handler(outputStream* st, int sig, 4441 char* buf, size_t buflen) { 4442 struct sigaction sa; 4443 4444 sigaction(sig, NULL, &sa); 4445 4446 // See comment for SIGNIFICANT_SIGNAL_MASK define 4447 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4448 4449 st->print("%s: ", os::exception_name(sig, buf, buflen)); 4450 4451 address handler = (sa.sa_flags & SA_SIGINFO) 4452 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 4453 : CAST_FROM_FN_PTR(address, sa.sa_handler); 4454 4455 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 4456 st->print("SIG_DFL"); 4457 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 4458 st->print("SIG_IGN"); 4459 } else { 4460 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 4461 } 4462 4463 st->print(", sa_mask[0]="); 4464 os::Posix::print_signal_set_short(st, &sa.sa_mask); 4465 4466 address rh = VMError::get_resetted_sighandler(sig); 4467 // May be, handler was resetted by VMError? 4468 if (rh != NULL) { 4469 handler = rh; 4470 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 4471 } 4472 4473 st->print(", sa_flags="); 4474 os::Posix::print_sa_flags(st, sa.sa_flags); 4475 4476 // Check: is it our handler? 4477 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 4478 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 4479 // It is our signal handler 4480 // check for flags, reset system-used one! 4481 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 4482 st->print( 4483 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 4484 os::Linux::get_our_sigflags(sig)); 4485 } 4486 } 4487 st->cr(); 4488 } 4489 4490 4491 #define DO_SIGNAL_CHECK(sig) \ 4492 do { \ 4493 if (!sigismember(&check_signal_done, sig)) { \ 4494 os::Linux::check_signal_handler(sig); \ 4495 } \ 4496 } while (0) 4497 4498 // This method is a periodic task to check for misbehaving JNI applications 4499 // under CheckJNI, we can add any periodic checks here 4500 4501 void os::run_periodic_checks() { 4502 if (check_signals == false) return; 4503 4504 // SEGV and BUS if overridden could potentially prevent 4505 // generation of hs*.log in the event of a crash, debugging 4506 // such a case can be very challenging, so we absolutely 4507 // check the following for a good measure: 4508 DO_SIGNAL_CHECK(SIGSEGV); 4509 DO_SIGNAL_CHECK(SIGILL); 4510 DO_SIGNAL_CHECK(SIGFPE); 4511 DO_SIGNAL_CHECK(SIGBUS); 4512 DO_SIGNAL_CHECK(SIGPIPE); 4513 DO_SIGNAL_CHECK(SIGXFSZ); 4514 #if defined(PPC64) 4515 DO_SIGNAL_CHECK(SIGTRAP); 4516 #endif 4517 4518 // ReduceSignalUsage allows the user to override these handlers 4519 // see comments at the very top and jvm_solaris.h 4520 if (!ReduceSignalUsage) { 4521 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 4522 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 4523 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 4524 DO_SIGNAL_CHECK(BREAK_SIGNAL); 4525 } 4526 4527 DO_SIGNAL_CHECK(SR_signum); 4528 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 4529 } 4530 4531 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 4532 4533 static os_sigaction_t os_sigaction = NULL; 4534 4535 void os::Linux::check_signal_handler(int sig) { 4536 char buf[O_BUFLEN]; 4537 address jvmHandler = NULL; 4538 4539 4540 struct sigaction act; 4541 if (os_sigaction == NULL) { 4542 // only trust the default sigaction, in case it has been interposed 4543 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 4544 if (os_sigaction == NULL) return; 4545 } 4546 4547 os_sigaction(sig, (struct sigaction*)NULL, &act); 4548 4549 4550 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 4551 4552 address thisHandler = (act.sa_flags & SA_SIGINFO) 4553 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 4554 : CAST_FROM_FN_PTR(address, act.sa_handler); 4555 4556 4557 switch (sig) { 4558 case SIGSEGV: 4559 case SIGBUS: 4560 case SIGFPE: 4561 case SIGPIPE: 4562 case SIGILL: 4563 case SIGXFSZ: 4564 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 4565 break; 4566 4567 case SHUTDOWN1_SIGNAL: 4568 case SHUTDOWN2_SIGNAL: 4569 case SHUTDOWN3_SIGNAL: 4570 case BREAK_SIGNAL: 4571 jvmHandler = (address)user_handler(); 4572 break; 4573 4574 case INTERRUPT_SIGNAL: 4575 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 4576 break; 4577 4578 default: 4579 if (sig == SR_signum) { 4580 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 4581 } else { 4582 return; 4583 } 4584 break; 4585 } 4586 4587 if (thisHandler != jvmHandler) { 4588 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 4589 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 4590 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 4591 // No need to check this sig any longer 4592 sigaddset(&check_signal_done, sig); 4593 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN 4594 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) { 4595 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell", 4596 exception_name(sig, buf, O_BUFLEN)); 4597 } 4598 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 4599 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 4600 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 4601 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 4602 // No need to check this sig any longer 4603 sigaddset(&check_signal_done, sig); 4604 } 4605 4606 // Dump all the signal 4607 if (sigismember(&check_signal_done, sig)) { 4608 print_signal_handlers(tty, buf, O_BUFLEN); 4609 } 4610 } 4611 4612 extern void report_error(char* file_name, int line_no, char* title, 4613 char* format, ...); 4614 4615 extern bool signal_name(int signo, char* buf, size_t len); 4616 4617 const char* os::exception_name(int exception_code, char* buf, size_t size) { 4618 if (0 < exception_code && exception_code <= SIGRTMAX) { 4619 // signal 4620 if (!signal_name(exception_code, buf, size)) { 4621 jio_snprintf(buf, size, "SIG%d", exception_code); 4622 } 4623 return buf; 4624 } else { 4625 return NULL; 4626 } 4627 } 4628 4629 // this is called _before_ the most of global arguments have been parsed 4630 void os::init(void) { 4631 char dummy; // used to get a guess on initial stack address 4632 // first_hrtime = gethrtime(); 4633 4634 // With LinuxThreads the JavaMain thread pid (primordial thread) 4635 // is different than the pid of the java launcher thread. 4636 // So, on Linux, the launcher thread pid is passed to the VM 4637 // via the sun.java.launcher.pid property. 4638 // Use this property instead of getpid() if it was correctly passed. 4639 // See bug 6351349. 4640 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 4641 4642 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 4643 4644 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 4645 4646 init_random(1234567); 4647 4648 ThreadCritical::initialize(); 4649 4650 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 4651 if (Linux::page_size() == -1) { 4652 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 4653 strerror(errno))); 4654 } 4655 init_page_sizes((size_t) Linux::page_size()); 4656 4657 Linux::initialize_system_info(); 4658 4659 // main_thread points to the aboriginal thread 4660 Linux::_main_thread = pthread_self(); 4661 4662 Linux::clock_init(); 4663 initial_time_count = javaTimeNanos(); 4664 4665 // pthread_condattr initialization for monotonic clock 4666 int status; 4667 pthread_condattr_t* _condattr = os::Linux::condAttr(); 4668 if ((status = pthread_condattr_init(_condattr)) != 0) { 4669 fatal(err_msg("pthread_condattr_init: %s", strerror(status))); 4670 } 4671 // Only set the clock if CLOCK_MONOTONIC is available 4672 if (os::supports_monotonic_clock()) { 4673 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) { 4674 if (status == EINVAL) { 4675 warning("Unable to use monotonic clock with relative timed-waits" \ 4676 " - changes to the time-of-day clock may have adverse affects"); 4677 } else { 4678 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status))); 4679 } 4680 } 4681 } 4682 // else it defaults to CLOCK_REALTIME 4683 4684 // If the pagesize of the VM is greater than 8K determine the appropriate 4685 // number of initial guard pages. The user can change this with the 4686 // command line arguments, if needed. 4687 if (vm_page_size() > (int)Linux::vm_default_page_size()) { 4688 StackYellowPages = 1; 4689 StackRedPages = 1; 4690 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size(); 4691 } 4692 4693 // retrieve entry point for pthread_setname_np 4694 Linux::_pthread_setname_np = 4695 (int(*)(pthread_t, const char*))dlsym(RTLD_DEFAULT, "pthread_setname_np"); 4696 4697 } 4698 4699 // To install functions for atexit system call 4700 extern "C" { 4701 static void perfMemory_exit_helper() { 4702 perfMemory_exit(); 4703 } 4704 } 4705 4706 // this is called _after_ the global arguments have been parsed 4707 jint os::init_2(void) { 4708 Linux::fast_thread_clock_init(); 4709 4710 // Allocate a single page and mark it as readable for safepoint polling 4711 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4712 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page"); 4713 4714 os::set_polling_page(polling_page); 4715 4716 #ifndef PRODUCT 4717 if (Verbose && PrintMiscellaneous) { 4718 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", 4719 (intptr_t)polling_page); 4720 } 4721 #endif 4722 4723 if (!UseMembar) { 4724 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 4725 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page"); 4726 os::set_memory_serialize_page(mem_serialize_page); 4727 4728 #ifndef PRODUCT 4729 if (Verbose && PrintMiscellaneous) { 4730 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", 4731 (intptr_t)mem_serialize_page); 4732 } 4733 #endif 4734 } 4735 4736 // initialize suspend/resume support - must do this before signal_sets_init() 4737 if (SR_initialize() != 0) { 4738 perror("SR_initialize failed"); 4739 return JNI_ERR; 4740 } 4741 4742 Linux::signal_sets_init(); 4743 Linux::install_signal_handlers(); 4744 4745 // Check minimum allowable stack size for thread creation and to initialize 4746 // the java system classes, including StackOverflowError - depends on page 4747 // size. Add a page for compiler2 recursion in main thread. 4748 // Add in 2*BytesPerWord times page size to account for VM stack during 4749 // class initialization depending on 32 or 64 bit VM. 4750 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed, 4751 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() + 4752 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size()); 4753 4754 size_t threadStackSizeInBytes = ThreadStackSize * K; 4755 if (threadStackSizeInBytes != 0 && 4756 threadStackSizeInBytes < os::Linux::min_stack_allowed) { 4757 tty->print_cr("\nThe stack size specified is too small, " 4758 "Specify at least %dk", 4759 os::Linux::min_stack_allowed/ K); 4760 return JNI_ERR; 4761 } 4762 4763 // Make the stack size a multiple of the page size so that 4764 // the yellow/red zones can be guarded. 4765 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 4766 vm_page_size())); 4767 4768 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 4769 4770 #if defined(IA32) 4771 workaround_expand_exec_shield_cs_limit(); 4772 #endif 4773 4774 Linux::libpthread_init(); 4775 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4776 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 4777 Linux::glibc_version(), Linux::libpthread_version(), 4778 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 4779 } 4780 4781 if (UseNUMA) { 4782 if (!Linux::libnuma_init()) { 4783 UseNUMA = false; 4784 } else { 4785 if ((Linux::numa_max_node() < 1)) { 4786 // There's only one node(they start from 0), disable NUMA. 4787 UseNUMA = false; 4788 } 4789 } 4790 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way 4791 // we can make the adaptive lgrp chunk resizing work. If the user specified 4792 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and 4793 // disable adaptive resizing. 4794 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) { 4795 if (FLAG_IS_DEFAULT(UseNUMA)) { 4796 UseNUMA = false; 4797 } else { 4798 if (FLAG_IS_DEFAULT(UseLargePages) && 4799 FLAG_IS_DEFAULT(UseSHM) && 4800 FLAG_IS_DEFAULT(UseHugeTLBFS)) { 4801 UseLargePages = false; 4802 } else { 4803 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing"); 4804 UseAdaptiveSizePolicy = false; 4805 UseAdaptiveNUMAChunkSizing = false; 4806 } 4807 } 4808 } 4809 if (!UseNUMA && ForceNUMA) { 4810 UseNUMA = true; 4811 } 4812 } 4813 4814 if (MaxFDLimit) { 4815 // set the number of file descriptors to max. print out error 4816 // if getrlimit/setrlimit fails but continue regardless. 4817 struct rlimit nbr_files; 4818 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 4819 if (status != 0) { 4820 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4821 perror("os::init_2 getrlimit failed"); 4822 } 4823 } else { 4824 nbr_files.rlim_cur = nbr_files.rlim_max; 4825 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 4826 if (status != 0) { 4827 if (PrintMiscellaneous && (Verbose || WizardMode)) { 4828 perror("os::init_2 setrlimit failed"); 4829 } 4830 } 4831 } 4832 } 4833 4834 // Initialize lock used to serialize thread creation (see os::create_thread) 4835 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 4836 4837 // at-exit methods are called in the reverse order of their registration. 4838 // atexit functions are called on return from main or as a result of a 4839 // call to exit(3C). There can be only 32 of these functions registered 4840 // and atexit() does not set errno. 4841 4842 if (PerfAllowAtExitRegistration) { 4843 // only register atexit functions if PerfAllowAtExitRegistration is set. 4844 // atexit functions can be delayed until process exit time, which 4845 // can be problematic for embedded VM situations. Embedded VMs should 4846 // call DestroyJavaVM() to assure that VM resources are released. 4847 4848 // note: perfMemory_exit_helper atexit function may be removed in 4849 // the future if the appropriate cleanup code can be added to the 4850 // VM_Exit VMOperation's doit method. 4851 if (atexit(perfMemory_exit_helper) != 0) { 4852 warning("os::init_2 atexit(perfMemory_exit_helper) failed"); 4853 } 4854 } 4855 4856 // initialize thread priority policy 4857 prio_init(); 4858 4859 return JNI_OK; 4860 } 4861 4862 // Mark the polling page as unreadable 4863 void os::make_polling_page_unreadable(void) { 4864 if (!guard_memory((char*)_polling_page, Linux::page_size())) { 4865 fatal("Could not disable polling page"); 4866 } 4867 } 4868 4869 // Mark the polling page as readable 4870 void os::make_polling_page_readable(void) { 4871 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 4872 fatal("Could not enable polling page"); 4873 } 4874 } 4875 4876 int os::active_processor_count() { 4877 // Linux doesn't yet have a (official) notion of processor sets, 4878 // so just return the number of online processors. 4879 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 4880 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 4881 return online_cpus; 4882 } 4883 4884 void os::set_native_thread_name(const char *name) { 4885 if (Linux::_pthread_setname_np) { 4886 char buf [16]; // according to glibc manpage, 16 chars incl. '/0' 4887 snprintf(buf, sizeof(buf), "%s", name); 4888 buf[sizeof(buf) - 1] = '\0'; 4889 const int rc = Linux::_pthread_setname_np(pthread_self(), buf); 4890 // ERANGE should not happen; all other errors should just be ignored. 4891 assert(rc != ERANGE, "pthread_setname_np failed"); 4892 } 4893 } 4894 4895 bool os::distribute_processes(uint length, uint* distribution) { 4896 // Not yet implemented. 4897 return false; 4898 } 4899 4900 bool os::bind_to_processor(uint processor_id) { 4901 // Not yet implemented. 4902 return false; 4903 } 4904 4905 /// 4906 4907 void os::SuspendedThreadTask::internal_do_task() { 4908 if (do_suspend(_thread->osthread())) { 4909 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext()); 4910 do_task(context); 4911 do_resume(_thread->osthread()); 4912 } 4913 } 4914 4915 class PcFetcher : public os::SuspendedThreadTask { 4916 public: 4917 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} 4918 ExtendedPC result(); 4919 protected: 4920 void do_task(const os::SuspendedThreadTaskContext& context); 4921 private: 4922 ExtendedPC _epc; 4923 }; 4924 4925 ExtendedPC PcFetcher::result() { 4926 guarantee(is_done(), "task is not done yet."); 4927 return _epc; 4928 } 4929 4930 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { 4931 Thread* thread = context.thread(); 4932 OSThread* osthread = thread->osthread(); 4933 if (osthread->ucontext() != NULL) { 4934 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext()); 4935 } else { 4936 // NULL context is unexpected, double-check this is the VMThread 4937 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4938 } 4939 } 4940 4941 // Suspends the target using the signal mechanism and then grabs the PC before 4942 // resuming the target. Used by the flat-profiler only 4943 ExtendedPC os::get_thread_pc(Thread* thread) { 4944 // Make sure that it is called by the watcher for the VMThread 4945 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4946 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4947 4948 PcFetcher fetcher(thread); 4949 fetcher.run(); 4950 return fetcher.result(); 4951 } 4952 4953 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, 4954 pthread_mutex_t *_mutex, 4955 const struct timespec *_abstime) { 4956 if (is_NPTL()) { 4957 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4958 } else { 4959 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4960 // word back to default 64bit precision if condvar is signaled. Java 4961 // wants 53bit precision. Save and restore current value. 4962 int fpu = get_fpu_control_word(); 4963 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4964 set_fpu_control_word(fpu); 4965 return status; 4966 } 4967 } 4968 4969 //////////////////////////////////////////////////////////////////////////////// 4970 // debug support 4971 4972 bool os::find(address addr, outputStream* st) { 4973 Dl_info dlinfo; 4974 memset(&dlinfo, 0, sizeof(dlinfo)); 4975 if (dladdr(addr, &dlinfo) != 0) { 4976 st->print(PTR_FORMAT ": ", addr); 4977 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) { 4978 st->print("%s+%#x", dlinfo.dli_sname, 4979 addr - (intptr_t)dlinfo.dli_saddr); 4980 } else if (dlinfo.dli_fbase != NULL) { 4981 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4982 } else { 4983 st->print("<absolute address>"); 4984 } 4985 if (dlinfo.dli_fname != NULL) { 4986 st->print(" in %s", dlinfo.dli_fname); 4987 } 4988 if (dlinfo.dli_fbase != NULL) { 4989 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4990 } 4991 st->cr(); 4992 4993 if (Verbose) { 4994 // decode some bytes around the PC 4995 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size()); 4996 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size()); 4997 address lowest = (address) dlinfo.dli_sname; 4998 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4999 if (begin < lowest) begin = lowest; 5000 Dl_info dlinfo2; 5001 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr 5002 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) { 5003 end = (address) dlinfo2.dli_saddr; 5004 } 5005 Disassembler::decode(begin, end, st); 5006 } 5007 return true; 5008 } 5009 return false; 5010 } 5011 5012 //////////////////////////////////////////////////////////////////////////////// 5013 // misc 5014 5015 // This does not do anything on Linux. This is basically a hook for being 5016 // able to use structured exception handling (thread-local exception filters) 5017 // on, e.g., Win32. 5018 void 5019 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 5020 JavaCallArguments* args, Thread* thread) { 5021 f(value, method, args, thread); 5022 } 5023 5024 void os::print_statistics() { 5025 } 5026 5027 int os::message_box(const char* title, const char* message) { 5028 int i; 5029 fdStream err(defaultStream::error_fd()); 5030 for (i = 0; i < 78; i++) err.print_raw("="); 5031 err.cr(); 5032 err.print_raw_cr(title); 5033 for (i = 0; i < 78; i++) err.print_raw("-"); 5034 err.cr(); 5035 err.print_raw_cr(message); 5036 for (i = 0; i < 78; i++) err.print_raw("="); 5037 err.cr(); 5038 5039 char buf[16]; 5040 // Prevent process from exiting upon "read error" without consuming all CPU 5041 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 5042 5043 return buf[0] == 'y' || buf[0] == 'Y'; 5044 } 5045 5046 int os::stat(const char *path, struct stat *sbuf) { 5047 char pathbuf[MAX_PATH]; 5048 if (strlen(path) > MAX_PATH - 1) { 5049 errno = ENAMETOOLONG; 5050 return -1; 5051 } 5052 os::native_path(strcpy(pathbuf, path)); 5053 return ::stat(pathbuf, sbuf); 5054 } 5055 5056 bool os::check_heap(bool force) { 5057 return true; 5058 } 5059 5060 // Is a (classpath) directory empty? 5061 bool os::dir_is_empty(const char* path) { 5062 DIR *dir = NULL; 5063 struct dirent *ptr; 5064 5065 dir = opendir(path); 5066 if (dir == NULL) return true; 5067 5068 // Scan the directory 5069 bool result = true; 5070 char buf[sizeof(struct dirent) + MAX_PATH]; 5071 while (result && (ptr = ::readdir(dir)) != NULL) { 5072 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 5073 result = false; 5074 } 5075 } 5076 closedir(dir); 5077 return result; 5078 } 5079 5080 // This code originates from JDK's sysOpen and open64_w 5081 // from src/solaris/hpi/src/system_md.c 5082 5083 int os::open(const char *path, int oflag, int mode) { 5084 if (strlen(path) > MAX_PATH - 1) { 5085 errno = ENAMETOOLONG; 5086 return -1; 5087 } 5088 5089 // All file descriptors that are opened in the Java process and not 5090 // specifically destined for a subprocess should have the close-on-exec 5091 // flag set. If we don't set it, then careless 3rd party native code 5092 // might fork and exec without closing all appropriate file descriptors 5093 // (e.g. as we do in closeDescriptors in UNIXProcess.c), and this in 5094 // turn might: 5095 // 5096 // - cause end-of-file to fail to be detected on some file 5097 // descriptors, resulting in mysterious hangs, or 5098 // 5099 // - might cause an fopen in the subprocess to fail on a system 5100 // suffering from bug 1085341. 5101 // 5102 // (Yes, the default setting of the close-on-exec flag is a Unix 5103 // design flaw) 5104 // 5105 // See: 5106 // 1085341: 32-bit stdio routines should support file descriptors >255 5107 // 4843136: (process) pipe file descriptor from Runtime.exec not being closed 5108 // 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9 5109 // 5110 // Modern Linux kernels (after 2.6.23 2007) support O_CLOEXEC with open(). 5111 // O_CLOEXEC is preferable to using FD_CLOEXEC on an open file descriptor 5112 // because it saves a system call and removes a small window where the flag 5113 // is unset. On ancient Linux kernels the O_CLOEXEC flag will be ignored 5114 // and we fall back to using FD_CLOEXEC (see below). 5115 #ifdef O_CLOEXEC 5116 oflag |= O_CLOEXEC; 5117 #endif 5118 5119 int fd = ::open64(path, oflag, mode); 5120 if (fd == -1) return -1; 5121 5122 //If the open succeeded, the file might still be a directory 5123 { 5124 struct stat64 buf64; 5125 int ret = ::fstat64(fd, &buf64); 5126 int st_mode = buf64.st_mode; 5127 5128 if (ret != -1) { 5129 if ((st_mode & S_IFMT) == S_IFDIR) { 5130 errno = EISDIR; 5131 ::close(fd); 5132 return -1; 5133 } 5134 } else { 5135 ::close(fd); 5136 return -1; 5137 } 5138 } 5139 5140 #ifdef FD_CLOEXEC 5141 // Validate that the use of the O_CLOEXEC flag on open above worked. 5142 // With recent kernels, we will perform this check exactly once. 5143 static sig_atomic_t O_CLOEXEC_is_known_to_work = 0; 5144 if (!O_CLOEXEC_is_known_to_work) { 5145 int flags = ::fcntl(fd, F_GETFD); 5146 if (flags != -1) { 5147 if ((flags & FD_CLOEXEC) != 0) 5148 O_CLOEXEC_is_known_to_work = 1; 5149 else 5150 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC); 5151 } 5152 } 5153 #endif 5154 5155 return fd; 5156 } 5157 5158 5159 // create binary file, rewriting existing file if required 5160 int os::create_binary_file(const char* path, bool rewrite_existing) { 5161 int oflags = O_WRONLY | O_CREAT; 5162 if (!rewrite_existing) { 5163 oflags |= O_EXCL; 5164 } 5165 return ::open64(path, oflags, S_IREAD | S_IWRITE); 5166 } 5167 5168 // return current position of file pointer 5169 jlong os::current_file_offset(int fd) { 5170 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 5171 } 5172 5173 // move file pointer to the specified offset 5174 jlong os::seek_to_file_offset(int fd, jlong offset) { 5175 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 5176 } 5177 5178 // This code originates from JDK's sysAvailable 5179 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c 5180 5181 int os::available(int fd, jlong *bytes) { 5182 jlong cur, end; 5183 int mode; 5184 struct stat64 buf64; 5185 5186 if (::fstat64(fd, &buf64) >= 0) { 5187 mode = buf64.st_mode; 5188 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { 5189 // XXX: is the following call interruptible? If so, this might 5190 // need to go through the INTERRUPT_IO() wrapper as for other 5191 // blocking, interruptible calls in this file. 5192 int n; 5193 if (::ioctl(fd, FIONREAD, &n) >= 0) { 5194 *bytes = n; 5195 return 1; 5196 } 5197 } 5198 } 5199 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) { 5200 return 0; 5201 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) { 5202 return 0; 5203 } else if (::lseek64(fd, cur, SEEK_SET) == -1) { 5204 return 0; 5205 } 5206 *bytes = end - cur; 5207 return 1; 5208 } 5209 5210 // Map a block of memory. 5211 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset, 5212 char *addr, size_t bytes, bool read_only, 5213 bool allow_exec) { 5214 int prot; 5215 int flags = MAP_PRIVATE; 5216 5217 if (read_only) { 5218 prot = PROT_READ; 5219 } else { 5220 prot = PROT_READ | PROT_WRITE; 5221 } 5222 5223 if (allow_exec) { 5224 prot |= PROT_EXEC; 5225 } 5226 5227 if (addr != NULL) { 5228 flags |= MAP_FIXED; 5229 } 5230 5231 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 5232 fd, file_offset); 5233 if (mapped_address == MAP_FAILED) { 5234 return NULL; 5235 } 5236 return mapped_address; 5237 } 5238 5239 5240 // Remap a block of memory. 5241 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset, 5242 char *addr, size_t bytes, bool read_only, 5243 bool allow_exec) { 5244 // same as map_memory() on this OS 5245 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 5246 allow_exec); 5247 } 5248 5249 5250 // Unmap a block of memory. 5251 bool os::pd_unmap_memory(char* addr, size_t bytes) { 5252 return munmap(addr, bytes) == 0; 5253 } 5254 5255 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 5256 5257 static clockid_t thread_cpu_clockid(Thread* thread) { 5258 pthread_t tid = thread->osthread()->pthread_id(); 5259 clockid_t clockid; 5260 5261 // Get thread clockid 5262 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 5263 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 5264 return clockid; 5265 } 5266 5267 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 5268 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 5269 // of a thread. 5270 // 5271 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 5272 // the fast estimate available on the platform. 5273 5274 jlong os::current_thread_cpu_time() { 5275 if (os::Linux::supports_fast_thread_cpu_time()) { 5276 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5277 } else { 5278 // return user + sys since the cost is the same 5279 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 5280 } 5281 } 5282 5283 jlong os::thread_cpu_time(Thread* thread) { 5284 // consistent with what current_thread_cpu_time() returns 5285 if (os::Linux::supports_fast_thread_cpu_time()) { 5286 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5287 } else { 5288 return slow_thread_cpu_time(thread, true /* user + sys */); 5289 } 5290 } 5291 5292 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 5293 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5294 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 5295 } else { 5296 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 5297 } 5298 } 5299 5300 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5301 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 5302 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 5303 } else { 5304 return slow_thread_cpu_time(thread, user_sys_cpu_time); 5305 } 5306 } 5307 5308 // -1 on error. 5309 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 5310 pid_t tid = thread->osthread()->thread_id(); 5311 char *s; 5312 char stat[2048]; 5313 int statlen; 5314 char proc_name[64]; 5315 int count; 5316 long sys_time, user_time; 5317 char cdummy; 5318 int idummy; 5319 long ldummy; 5320 FILE *fp; 5321 5322 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid); 5323 fp = fopen(proc_name, "r"); 5324 if (fp == NULL) return -1; 5325 statlen = fread(stat, 1, 2047, fp); 5326 stat[statlen] = '\0'; 5327 fclose(fp); 5328 5329 // Skip pid and the command string. Note that we could be dealing with 5330 // weird command names, e.g. user could decide to rename java launcher 5331 // to "java 1.4.2 :)", then the stat file would look like 5332 // 1234 (java 1.4.2 :)) R ... ... 5333 // We don't really need to know the command string, just find the last 5334 // occurrence of ")" and then start parsing from there. See bug 4726580. 5335 s = strrchr(stat, ')'); 5336 if (s == NULL) return -1; 5337 5338 // Skip blank chars 5339 do { s++; } while (s && isspace(*s)); 5340 5341 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 5342 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy, 5343 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 5344 &user_time, &sys_time); 5345 if (count != 13) return -1; 5346 if (user_sys_cpu_time) { 5347 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 5348 } else { 5349 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 5350 } 5351 } 5352 5353 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5354 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5355 info_ptr->may_skip_backward = false; // elapsed time not wall time 5356 info_ptr->may_skip_forward = false; // elapsed time not wall time 5357 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5358 } 5359 5360 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 5361 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 5362 info_ptr->may_skip_backward = false; // elapsed time not wall time 5363 info_ptr->may_skip_forward = false; // elapsed time not wall time 5364 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 5365 } 5366 5367 bool os::is_thread_cpu_time_supported() { 5368 return true; 5369 } 5370 5371 // System loadavg support. Returns -1 if load average cannot be obtained. 5372 // Linux doesn't yet have a (official) notion of processor sets, 5373 // so just return the system wide load average. 5374 int os::loadavg(double loadavg[], int nelem) { 5375 return ::getloadavg(loadavg, nelem); 5376 } 5377 5378 void os::pause() { 5379 char filename[MAX_PATH]; 5380 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 5381 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 5382 } else { 5383 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 5384 } 5385 5386 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 5387 if (fd != -1) { 5388 struct stat buf; 5389 ::close(fd); 5390 while (::stat(filename, &buf) == 0) { 5391 (void)::poll(NULL, 0, 100); 5392 } 5393 } else { 5394 jio_fprintf(stderr, 5395 "Could not open pause file '%s', continuing immediately.\n", filename); 5396 } 5397 } 5398 5399 5400 // Refer to the comments in os_solaris.cpp park-unpark. The next two 5401 // comment paragraphs are worth repeating here: 5402 // 5403 // Assumption: 5404 // Only one parker can exist on an event, which is why we allocate 5405 // them per-thread. Multiple unparkers can coexist. 5406 // 5407 // _Event serves as a restricted-range semaphore. 5408 // -1 : thread is blocked, i.e. there is a waiter 5409 // 0 : neutral: thread is running or ready, 5410 // could have been signaled after a wait started 5411 // 1 : signaled - thread is running or ready 5412 // 5413 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 5414 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 5415 // For specifics regarding the bug see GLIBC BUGID 261237 : 5416 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 5417 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 5418 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 5419 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 5420 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 5421 // and monitorenter when we're using 1-0 locking. All those operations may result in 5422 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 5423 // of libpthread avoids the problem, but isn't practical. 5424 // 5425 // Possible remedies: 5426 // 5427 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 5428 // This is palliative and probabilistic, however. If the thread is preempted 5429 // between the call to compute_abstime() and pthread_cond_timedwait(), more 5430 // than the minimum period may have passed, and the abstime may be stale (in the 5431 // past) resultin in a hang. Using this technique reduces the odds of a hang 5432 // but the JVM is still vulnerable, particularly on heavily loaded systems. 5433 // 5434 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 5435 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 5436 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 5437 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 5438 // thread. 5439 // 5440 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 5441 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 5442 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 5443 // This also works well. In fact it avoids kernel-level scalability impediments 5444 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 5445 // timers in a graceful fashion. 5446 // 5447 // 4. When the abstime value is in the past it appears that control returns 5448 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 5449 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 5450 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 5451 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 5452 // It may be possible to avoid reinitialization by checking the return 5453 // value from pthread_cond_timedwait(). In addition to reinitializing the 5454 // condvar we must establish the invariant that cond_signal() is only called 5455 // within critical sections protected by the adjunct mutex. This prevents 5456 // cond_signal() from "seeing" a condvar that's in the midst of being 5457 // reinitialized or that is corrupt. Sadly, this invariant obviates the 5458 // desirable signal-after-unlock optimization that avoids futile context switching. 5459 // 5460 // I'm also concerned that some versions of NTPL might allocate an auxilliary 5461 // structure when a condvar is used or initialized. cond_destroy() would 5462 // release the helper structure. Our reinitialize-after-timedwait fix 5463 // put excessive stress on malloc/free and locks protecting the c-heap. 5464 // 5465 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 5466 // It may be possible to refine (4) by checking the kernel and NTPL verisons 5467 // and only enabling the work-around for vulnerable environments. 5468 5469 // utility to compute the abstime argument to timedwait: 5470 // millis is the relative timeout time 5471 // abstime will be the absolute timeout time 5472 // TODO: replace compute_abstime() with unpackTime() 5473 5474 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 5475 if (millis < 0) millis = 0; 5476 5477 jlong seconds = millis / 1000; 5478 millis %= 1000; 5479 if (seconds > 50000000) { // see man cond_timedwait(3T) 5480 seconds = 50000000; 5481 } 5482 5483 if (os::supports_monotonic_clock()) { 5484 struct timespec now; 5485 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5486 assert_status(status == 0, status, "clock_gettime"); 5487 abstime->tv_sec = now.tv_sec + seconds; 5488 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC; 5489 if (nanos >= NANOSECS_PER_SEC) { 5490 abstime->tv_sec += 1; 5491 nanos -= NANOSECS_PER_SEC; 5492 } 5493 abstime->tv_nsec = nanos; 5494 } else { 5495 struct timeval now; 5496 int status = gettimeofday(&now, NULL); 5497 assert(status == 0, "gettimeofday"); 5498 abstime->tv_sec = now.tv_sec + seconds; 5499 long usec = now.tv_usec + millis * 1000; 5500 if (usec >= 1000000) { 5501 abstime->tv_sec += 1; 5502 usec -= 1000000; 5503 } 5504 abstime->tv_nsec = usec * 1000; 5505 } 5506 return abstime; 5507 } 5508 5509 void os::PlatformEvent::park() { // AKA "down()" 5510 // Transitions for _Event: 5511 // -1 => -1 : illegal 5512 // 1 => 0 : pass - return immediately 5513 // 0 => -1 : block; then set _Event to 0 before returning 5514 5515 // Invariant: Only the thread associated with the Event/PlatformEvent 5516 // may call park(). 5517 // TODO: assert that _Assoc != NULL or _Assoc == Self 5518 assert(_nParked == 0, "invariant"); 5519 5520 int v; 5521 for (;;) { 5522 v = _Event; 5523 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5524 } 5525 guarantee(v >= 0, "invariant"); 5526 if (v == 0) { 5527 // Do this the hard way by blocking ... 5528 int status = pthread_mutex_lock(_mutex); 5529 assert_status(status == 0, status, "mutex_lock"); 5530 guarantee(_nParked == 0, "invariant"); 5531 ++_nParked; 5532 while (_Event < 0) { 5533 status = pthread_cond_wait(_cond, _mutex); 5534 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 5535 // Treat this the same as if the wait was interrupted 5536 if (status == ETIME) { status = EINTR; } 5537 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 5538 } 5539 --_nParked; 5540 5541 _Event = 0; 5542 status = pthread_mutex_unlock(_mutex); 5543 assert_status(status == 0, status, "mutex_unlock"); 5544 // Paranoia to ensure our locked and lock-free paths interact 5545 // correctly with each other. 5546 OrderAccess::fence(); 5547 } 5548 guarantee(_Event >= 0, "invariant"); 5549 } 5550 5551 int os::PlatformEvent::park(jlong millis) { 5552 // Transitions for _Event: 5553 // -1 => -1 : illegal 5554 // 1 => 0 : pass - return immediately 5555 // 0 => -1 : block; then set _Event to 0 before returning 5556 5557 guarantee(_nParked == 0, "invariant"); 5558 5559 int v; 5560 for (;;) { 5561 v = _Event; 5562 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break; 5563 } 5564 guarantee(v >= 0, "invariant"); 5565 if (v != 0) return OS_OK; 5566 5567 // We do this the hard way, by blocking the thread. 5568 // Consider enforcing a minimum timeout value. 5569 struct timespec abst; 5570 compute_abstime(&abst, millis); 5571 5572 int ret = OS_TIMEOUT; 5573 int status = pthread_mutex_lock(_mutex); 5574 assert_status(status == 0, status, "mutex_lock"); 5575 guarantee(_nParked == 0, "invariant"); 5576 ++_nParked; 5577 5578 // Object.wait(timo) will return because of 5579 // (a) notification 5580 // (b) timeout 5581 // (c) thread.interrupt 5582 // 5583 // Thread.interrupt and object.notify{All} both call Event::set. 5584 // That is, we treat thread.interrupt as a special case of notification. 5585 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false. 5586 // We assume all ETIME returns are valid. 5587 // 5588 // TODO: properly differentiate simultaneous notify+interrupt. 5589 // In that case, we should propagate the notify to another waiter. 5590 5591 while (_Event < 0) { 5592 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 5593 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5594 pthread_cond_destroy(_cond); 5595 pthread_cond_init(_cond, os::Linux::condAttr()); 5596 } 5597 assert_status(status == 0 || status == EINTR || 5598 status == ETIME || status == ETIMEDOUT, 5599 status, "cond_timedwait"); 5600 if (!FilterSpuriousWakeups) break; // previous semantics 5601 if (status == ETIME || status == ETIMEDOUT) break; 5602 // We consume and ignore EINTR and spurious wakeups. 5603 } 5604 --_nParked; 5605 if (_Event >= 0) { 5606 ret = OS_OK; 5607 } 5608 _Event = 0; 5609 status = pthread_mutex_unlock(_mutex); 5610 assert_status(status == 0, status, "mutex_unlock"); 5611 assert(_nParked == 0, "invariant"); 5612 // Paranoia to ensure our locked and lock-free paths interact 5613 // correctly with each other. 5614 OrderAccess::fence(); 5615 return ret; 5616 } 5617 5618 void os::PlatformEvent::unpark() { 5619 // Transitions for _Event: 5620 // 0 => 1 : just return 5621 // 1 => 1 : just return 5622 // -1 => either 0 or 1; must signal target thread 5623 // That is, we can safely transition _Event from -1 to either 5624 // 0 or 1. 5625 // See also: "Semaphores in Plan 9" by Mullender & Cox 5626 // 5627 // Note: Forcing a transition from "-1" to "1" on an unpark() means 5628 // that it will take two back-to-back park() calls for the owning 5629 // thread to block. This has the benefit of forcing a spurious return 5630 // from the first park() call after an unpark() call which will help 5631 // shake out uses of park() and unpark() without condition variables. 5632 5633 if (Atomic::xchg(1, &_Event) >= 0) return; 5634 5635 // Wait for the thread associated with the event to vacate 5636 int status = pthread_mutex_lock(_mutex); 5637 assert_status(status == 0, status, "mutex_lock"); 5638 int AnyWaiters = _nParked; 5639 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant"); 5640 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 5641 AnyWaiters = 0; 5642 pthread_cond_signal(_cond); 5643 } 5644 status = pthread_mutex_unlock(_mutex); 5645 assert_status(status == 0, status, "mutex_unlock"); 5646 if (AnyWaiters != 0) { 5647 // Note that we signal() *after* dropping the lock for "immortal" Events. 5648 // This is safe and avoids a common class of futile wakeups. In rare 5649 // circumstances this can cause a thread to return prematurely from 5650 // cond_{timed}wait() but the spurious wakeup is benign and the victim 5651 // will simply re-test the condition and re-park itself. 5652 // This provides particular benefit if the underlying platform does not 5653 // provide wait morphing. 5654 status = pthread_cond_signal(_cond); 5655 assert_status(status == 0, status, "cond_signal"); 5656 } 5657 } 5658 5659 5660 // JSR166 5661 // ------------------------------------------------------- 5662 5663 // The solaris and linux implementations of park/unpark are fairly 5664 // conservative for now, but can be improved. They currently use a 5665 // mutex/condvar pair, plus a a count. 5666 // Park decrements count if > 0, else does a condvar wait. Unpark 5667 // sets count to 1 and signals condvar. Only one thread ever waits 5668 // on the condvar. Contention seen when trying to park implies that someone 5669 // is unparking you, so don't wait. And spurious returns are fine, so there 5670 // is no need to track notifications. 5671 5672 // This code is common to linux and solaris and will be moved to a 5673 // common place in dolphin. 5674 // 5675 // The passed in time value is either a relative time in nanoseconds 5676 // or an absolute time in milliseconds. Either way it has to be unpacked 5677 // into suitable seconds and nanoseconds components and stored in the 5678 // given timespec structure. 5679 // Given time is a 64-bit value and the time_t used in the timespec is only 5680 // a signed-32-bit value (except on 64-bit Linux) we have to watch for 5681 // overflow if times way in the future are given. Further on Solaris versions 5682 // prior to 10 there is a restriction (see cond_timedwait) that the specified 5683 // number of seconds, in abstime, is less than current_time + 100,000,000. 5684 // As it will be 28 years before "now + 100000000" will overflow we can 5685 // ignore overflow and just impose a hard-limit on seconds using the value 5686 // of "now + 100,000,000". This places a limit on the timeout of about 3.17 5687 // years from "now". 5688 5689 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 5690 assert(time > 0, "convertTime"); 5691 time_t max_secs = 0; 5692 5693 if (!os::supports_monotonic_clock() || isAbsolute) { 5694 struct timeval now; 5695 int status = gettimeofday(&now, NULL); 5696 assert(status == 0, "gettimeofday"); 5697 5698 max_secs = now.tv_sec + MAX_SECS; 5699 5700 if (isAbsolute) { 5701 jlong secs = time / 1000; 5702 if (secs > max_secs) { 5703 absTime->tv_sec = max_secs; 5704 } else { 5705 absTime->tv_sec = secs; 5706 } 5707 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 5708 } else { 5709 jlong secs = time / NANOSECS_PER_SEC; 5710 if (secs >= MAX_SECS) { 5711 absTime->tv_sec = max_secs; 5712 absTime->tv_nsec = 0; 5713 } else { 5714 absTime->tv_sec = now.tv_sec + secs; 5715 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 5716 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5717 absTime->tv_nsec -= NANOSECS_PER_SEC; 5718 ++absTime->tv_sec; // note: this must be <= max_secs 5719 } 5720 } 5721 } 5722 } else { 5723 // must be relative using monotonic clock 5724 struct timespec now; 5725 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now); 5726 assert_status(status == 0, status, "clock_gettime"); 5727 max_secs = now.tv_sec + MAX_SECS; 5728 jlong secs = time / NANOSECS_PER_SEC; 5729 if (secs >= MAX_SECS) { 5730 absTime->tv_sec = max_secs; 5731 absTime->tv_nsec = 0; 5732 } else { 5733 absTime->tv_sec = now.tv_sec + secs; 5734 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec; 5735 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 5736 absTime->tv_nsec -= NANOSECS_PER_SEC; 5737 ++absTime->tv_sec; // note: this must be <= max_secs 5738 } 5739 } 5740 } 5741 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 5742 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 5743 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 5744 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 5745 } 5746 5747 void Parker::park(bool isAbsolute, jlong time) { 5748 // Ideally we'd do something useful while spinning, such 5749 // as calling unpackTime(). 5750 5751 // Optional fast-path check: 5752 // Return immediately if a permit is available. 5753 // We depend on Atomic::xchg() having full barrier semantics 5754 // since we are doing a lock-free update to _counter. 5755 if (Atomic::xchg(0, &_counter) > 0) return; 5756 5757 Thread* thread = Thread::current(); 5758 assert(thread->is_Java_thread(), "Must be JavaThread"); 5759 JavaThread *jt = (JavaThread *)thread; 5760 5761 // Optional optimization -- avoid state transitions if there's an interrupt pending. 5762 // Check interrupt before trying to wait 5763 if (Thread::is_interrupted(thread, false)) { 5764 return; 5765 } 5766 5767 // Next, demultiplex/decode time arguments 5768 timespec absTime; 5769 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all 5770 return; 5771 } 5772 if (time > 0) { 5773 unpackTime(&absTime, isAbsolute, time); 5774 } 5775 5776 5777 // Enter safepoint region 5778 // Beware of deadlocks such as 6317397. 5779 // The per-thread Parker:: mutex is a classic leaf-lock. 5780 // In particular a thread must never block on the Threads_lock while 5781 // holding the Parker:: mutex. If safepoints are pending both the 5782 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 5783 ThreadBlockInVM tbivm(jt); 5784 5785 // Don't wait if cannot get lock since interference arises from 5786 // unblocking. Also. check interrupt before trying wait 5787 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 5788 return; 5789 } 5790 5791 int status; 5792 if (_counter > 0) { // no wait needed 5793 _counter = 0; 5794 status = pthread_mutex_unlock(_mutex); 5795 assert(status == 0, "invariant"); 5796 // Paranoia to ensure our locked and lock-free paths interact 5797 // correctly with each other and Java-level accesses. 5798 OrderAccess::fence(); 5799 return; 5800 } 5801 5802 #ifdef ASSERT 5803 // Don't catch signals while blocked; let the running threads have the signals. 5804 // (This allows a debugger to break into the running thread.) 5805 sigset_t oldsigs; 5806 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 5807 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 5808 #endif 5809 5810 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 5811 jt->set_suspend_equivalent(); 5812 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 5813 5814 assert(_cur_index == -1, "invariant"); 5815 if (time == 0) { 5816 _cur_index = REL_INDEX; // arbitrary choice when not timed 5817 status = pthread_cond_wait(&_cond[_cur_index], _mutex); 5818 } else { 5819 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; 5820 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime); 5821 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 5822 pthread_cond_destroy(&_cond[_cur_index]); 5823 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr()); 5824 } 5825 } 5826 _cur_index = -1; 5827 assert_status(status == 0 || status == EINTR || 5828 status == ETIME || status == ETIMEDOUT, 5829 status, "cond_timedwait"); 5830 5831 #ifdef ASSERT 5832 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 5833 #endif 5834 5835 _counter = 0; 5836 status = pthread_mutex_unlock(_mutex); 5837 assert_status(status == 0, status, "invariant"); 5838 // Paranoia to ensure our locked and lock-free paths interact 5839 // correctly with each other and Java-level accesses. 5840 OrderAccess::fence(); 5841 5842 // If externally suspended while waiting, re-suspend 5843 if (jt->handle_special_suspend_equivalent_condition()) { 5844 jt->java_suspend_self(); 5845 } 5846 } 5847 5848 void Parker::unpark() { 5849 int status = pthread_mutex_lock(_mutex); 5850 assert(status == 0, "invariant"); 5851 const int s = _counter; 5852 _counter = 1; 5853 if (s < 1) { 5854 // thread might be parked 5855 if (_cur_index != -1) { 5856 // thread is definitely parked 5857 if (WorkAroundNPTLTimedWaitHang) { 5858 status = pthread_cond_signal(&_cond[_cur_index]); 5859 assert(status == 0, "invariant"); 5860 status = pthread_mutex_unlock(_mutex); 5861 assert(status == 0, "invariant"); 5862 } else { 5863 status = pthread_mutex_unlock(_mutex); 5864 assert(status == 0, "invariant"); 5865 status = pthread_cond_signal(&_cond[_cur_index]); 5866 assert(status == 0, "invariant"); 5867 } 5868 } else { 5869 pthread_mutex_unlock(_mutex); 5870 assert(status == 0, "invariant"); 5871 } 5872 } else { 5873 pthread_mutex_unlock(_mutex); 5874 assert(status == 0, "invariant"); 5875 } 5876 } 5877 5878 5879 extern char** environ; 5880 5881 // Run the specified command in a separate process. Return its exit value, 5882 // or -1 on failure (e.g. can't fork a new process). 5883 // Unlike system(), this function can be called from signal handler. It 5884 // doesn't block SIGINT et al. 5885 int os::fork_and_exec(char* cmd) { 5886 const char * argv[4] = {"sh", "-c", cmd, NULL}; 5887 5888 pid_t pid = fork(); 5889 5890 if (pid < 0) { 5891 // fork failed 5892 return -1; 5893 5894 } else if (pid == 0) { 5895 // child process 5896 5897 execve("/bin/sh", (char* const*)argv, environ); 5898 5899 // execve failed 5900 _exit(-1); 5901 5902 } else { 5903 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 5904 // care about the actual exit code, for now. 5905 5906 int status; 5907 5908 // Wait for the child process to exit. This returns immediately if 5909 // the child has already exited. */ 5910 while (waitpid(pid, &status, 0) < 0) { 5911 switch (errno) { 5912 case ECHILD: return 0; 5913 case EINTR: break; 5914 default: return -1; 5915 } 5916 } 5917 5918 if (WIFEXITED(status)) { 5919 // The child exited normally; get its exit code. 5920 return WEXITSTATUS(status); 5921 } else if (WIFSIGNALED(status)) { 5922 // The child exited because of a signal 5923 // The best value to return is 0x80 + signal number, 5924 // because that is what all Unix shells do, and because 5925 // it allows callers to distinguish between process exit and 5926 // process death by signal. 5927 return 0x80 + WTERMSIG(status); 5928 } else { 5929 // Unknown exit code; pass it through 5930 return status; 5931 } 5932 } 5933 } 5934 5935 // is_headless_jre() 5936 // 5937 // Test for the existence of xawt/libmawt.so or libawt_xawt.so 5938 // in order to report if we are running in a headless jre 5939 // 5940 // Since JDK8 xawt/libmawt.so was moved into the same directory 5941 // as libawt.so, and renamed libawt_xawt.so 5942 // 5943 bool os::is_headless_jre() { 5944 struct stat statbuf; 5945 char buf[MAXPATHLEN]; 5946 char libmawtpath[MAXPATHLEN]; 5947 const char *xawtstr = "/xawt/libmawt.so"; 5948 const char *new_xawtstr = "/libawt_xawt.so"; 5949 char *p; 5950 5951 // Get path to libjvm.so 5952 os::jvm_path(buf, sizeof(buf)); 5953 5954 // Get rid of libjvm.so 5955 p = strrchr(buf, '/'); 5956 if (p == NULL) { 5957 return false; 5958 } else { 5959 *p = '\0'; 5960 } 5961 5962 // Get rid of client or server 5963 p = strrchr(buf, '/'); 5964 if (p == NULL) { 5965 return false; 5966 } else { 5967 *p = '\0'; 5968 } 5969 5970 // check xawt/libmawt.so 5971 strcpy(libmawtpath, buf); 5972 strcat(libmawtpath, xawtstr); 5973 if (::stat(libmawtpath, &statbuf) == 0) return false; 5974 5975 // check libawt_xawt.so 5976 strcpy(libmawtpath, buf); 5977 strcat(libmawtpath, new_xawtstr); 5978 if (::stat(libmawtpath, &statbuf) == 0) return false; 5979 5980 return true; 5981 } 5982 5983 // Get the default path to the core file 5984 // Returns the length of the string 5985 int os::get_core_path(char* buffer, size_t bufferSize) { 5986 /* 5987 * Max length of /proc/sys/kernel/core_pattern is 128 characters. 5988 * See https://www.kernel.org/doc/Documentation/sysctl/kernel.txt 5989 */ 5990 const int core_pattern_len = 129; 5991 char core_pattern[core_pattern_len] = {0}; 5992 5993 int core_pattern_file = ::open("/proc/sys/kernel/core_pattern", O_RDONLY); 5994 if (core_pattern_file != -1) { 5995 ssize_t ret = ::read(core_pattern_file, core_pattern, core_pattern_len); 5996 ::close(core_pattern_file); 5997 5998 if (ret > 0) { 5999 char *last_char = core_pattern + strlen(core_pattern) - 1; 6000 6001 if (*last_char == '\n') { 6002 *last_char = '\0'; 6003 } 6004 } 6005 } 6006 6007 if (strlen(core_pattern) == 0) { 6008 return -1; 6009 } 6010 6011 char *pid_pos = strstr(core_pattern, "%p"); 6012 int written; 6013 6014 if (core_pattern[0] == '/') { 6015 written = jio_snprintf(buffer, bufferSize, core_pattern); 6016 } else { 6017 char cwd[PATH_MAX]; 6018 6019 const char* p = get_current_directory(cwd, PATH_MAX); 6020 if (p == NULL) { 6021 return -1; 6022 } 6023 6024 if (core_pattern[0] == '|') { 6025 written = jio_snprintf(buffer, bufferSize, 6026 "\"%s\" (or dumping to %s/core.%d)", 6027 &core_pattern[1], p, current_process_id()); 6028 } else { 6029 written = jio_snprintf(buffer, bufferSize, "%s/%s", p, core_pattern); 6030 } 6031 } 6032 6033 if (written < 0) { 6034 return -1; 6035 } 6036 6037 if (((size_t)written < bufferSize) && (pid_pos == NULL) && (core_pattern[0] != '|')) { 6038 int core_uses_pid_file = ::open("/proc/sys/kernel/core_uses_pid", O_RDONLY); 6039 6040 if (core_uses_pid_file != -1) { 6041 char core_uses_pid = 0; 6042 ssize_t ret = ::read(core_uses_pid_file, &core_uses_pid, 1); 6043 ::close(core_uses_pid_file); 6044 6045 if (core_uses_pid == '1') { 6046 jio_snprintf(buffer + written, bufferSize - written, 6047 ".%d", current_process_id()); 6048 } 6049 } 6050 } 6051 6052 return strlen(buffer); 6053 } 6054 6055 /////////////// Unit tests /////////////// 6056 6057 #ifndef PRODUCT 6058 6059 #define test_log(...) \ 6060 do { \ 6061 if (VerboseInternalVMTests) { \ 6062 tty->print_cr(__VA_ARGS__); \ 6063 tty->flush(); \ 6064 } \ 6065 } while (false) 6066 6067 class TestReserveMemorySpecial : AllStatic { 6068 public: 6069 static void small_page_write(void* addr, size_t size) { 6070 size_t page_size = os::vm_page_size(); 6071 6072 char* end = (char*)addr + size; 6073 for (char* p = (char*)addr; p < end; p += page_size) { 6074 *p = 1; 6075 } 6076 } 6077 6078 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) { 6079 if (!UseHugeTLBFS) { 6080 return; 6081 } 6082 6083 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size); 6084 6085 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false); 6086 6087 if (addr != NULL) { 6088 small_page_write(addr, size); 6089 6090 os::Linux::release_memory_special_huge_tlbfs(addr, size); 6091 } 6092 } 6093 6094 static void test_reserve_memory_special_huge_tlbfs_only() { 6095 if (!UseHugeTLBFS) { 6096 return; 6097 } 6098 6099 size_t lp = os::large_page_size(); 6100 6101 for (size_t size = lp; size <= lp * 10; size += lp) { 6102 test_reserve_memory_special_huge_tlbfs_only(size); 6103 } 6104 } 6105 6106 static void test_reserve_memory_special_huge_tlbfs_mixed() { 6107 size_t lp = os::large_page_size(); 6108 size_t ag = os::vm_allocation_granularity(); 6109 6110 // sizes to test 6111 const size_t sizes[] = { 6112 lp, lp + ag, lp + lp / 2, lp * 2, 6113 lp * 2 + ag, lp * 2 - ag, lp * 2 + lp / 2, 6114 lp * 10, lp * 10 + lp / 2 6115 }; 6116 const int num_sizes = sizeof(sizes) / sizeof(size_t); 6117 6118 // For each size/alignment combination, we test three scenarios: 6119 // 1) with req_addr == NULL 6120 // 2) with a non-null req_addr at which we expect to successfully allocate 6121 // 3) with a non-null req_addr which contains a pre-existing mapping, at which we 6122 // expect the allocation to either fail or to ignore req_addr 6123 6124 // Pre-allocate two areas; they shall be as large as the largest allocation 6125 // and aligned to the largest alignment we will be testing. 6126 const size_t mapping_size = sizes[num_sizes - 1] * 2; 6127 char* const mapping1 = (char*) ::mmap(NULL, mapping_size, 6128 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, 6129 -1, 0); 6130 assert(mapping1 != MAP_FAILED, "should work"); 6131 6132 char* const mapping2 = (char*) ::mmap(NULL, mapping_size, 6133 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, 6134 -1, 0); 6135 assert(mapping2 != MAP_FAILED, "should work"); 6136 6137 // Unmap the first mapping, but leave the second mapping intact: the first 6138 // mapping will serve as a value for a "good" req_addr (case 2). The second 6139 // mapping, still intact, as "bad" req_addr (case 3). 6140 ::munmap(mapping1, mapping_size); 6141 6142 // Case 1 6143 test_log("%s, req_addr NULL:", __FUNCTION__); 6144 test_log("size align result"); 6145 6146 for (int i = 0; i < num_sizes; i++) { 6147 const size_t size = sizes[i]; 6148 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6149 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false); 6150 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " -> " PTR_FORMAT " %s", 6151 size, alignment, p, (p != NULL ? "" : "(failed)")); 6152 if (p != NULL) { 6153 assert(is_ptr_aligned(p, alignment), "must be"); 6154 small_page_write(p, size); 6155 os::Linux::release_memory_special_huge_tlbfs(p, size); 6156 } 6157 } 6158 } 6159 6160 // Case 2 6161 test_log("%s, req_addr non-NULL:", __FUNCTION__); 6162 test_log("size align req_addr result"); 6163 6164 for (int i = 0; i < num_sizes; i++) { 6165 const size_t size = sizes[i]; 6166 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6167 char* const req_addr = (char*) align_ptr_up(mapping1, alignment); 6168 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false); 6169 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s", 6170 size, alignment, req_addr, p, 6171 ((p != NULL ? (p == req_addr ? "(exact match)" : "") : "(failed)"))); 6172 if (p != NULL) { 6173 assert(p == req_addr, "must be"); 6174 small_page_write(p, size); 6175 os::Linux::release_memory_special_huge_tlbfs(p, size); 6176 } 6177 } 6178 } 6179 6180 // Case 3 6181 test_log("%s, req_addr non-NULL with preexisting mapping:", __FUNCTION__); 6182 test_log("size align req_addr result"); 6183 6184 for (int i = 0; i < num_sizes; i++) { 6185 const size_t size = sizes[i]; 6186 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6187 char* const req_addr = (char*) align_ptr_up(mapping2, alignment); 6188 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false); 6189 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s", 6190 size, alignment, req_addr, p, 6191 ((p != NULL ? "" : "(failed)"))); 6192 // as the area around req_addr contains already existing mappings, the API should always 6193 // return NULL (as per contract, it cannot return another address) 6194 assert(p == NULL, "must be"); 6195 } 6196 } 6197 6198 ::munmap(mapping2, mapping_size); 6199 6200 } 6201 6202 static void test_reserve_memory_special_huge_tlbfs() { 6203 if (!UseHugeTLBFS) { 6204 return; 6205 } 6206 6207 test_reserve_memory_special_huge_tlbfs_only(); 6208 test_reserve_memory_special_huge_tlbfs_mixed(); 6209 } 6210 6211 static void test_reserve_memory_special_shm(size_t size, size_t alignment) { 6212 if (!UseSHM) { 6213 return; 6214 } 6215 6216 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment); 6217 6218 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false); 6219 6220 if (addr != NULL) { 6221 assert(is_ptr_aligned(addr, alignment), "Check"); 6222 assert(is_ptr_aligned(addr, os::large_page_size()), "Check"); 6223 6224 small_page_write(addr, size); 6225 6226 os::Linux::release_memory_special_shm(addr, size); 6227 } 6228 } 6229 6230 static void test_reserve_memory_special_shm() { 6231 size_t lp = os::large_page_size(); 6232 size_t ag = os::vm_allocation_granularity(); 6233 6234 for (size_t size = ag; size < lp * 3; size += ag) { 6235 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) { 6236 test_reserve_memory_special_shm(size, alignment); 6237 } 6238 } 6239 } 6240 6241 static void test() { 6242 test_reserve_memory_special_huge_tlbfs(); 6243 test_reserve_memory_special_shm(); 6244 } 6245 }; 6246 6247 void TestReserveMemorySpecial_test() { 6248 TestReserveMemorySpecial::test(); 6249 } 6250 6251 #endif