1 /* 2 * Copyright (c) 1999, 2009, 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 # define __STDC_FORMAT_MACROS 26 27 // do not include precompiled header file 28 # include "incls/_os_linux.cpp.incl" 29 30 // put OS-includes here 31 # include <sys/types.h> 32 # include <sys/mman.h> 33 # include <pthread.h> 34 # include <signal.h> 35 # include <errno.h> 36 # include <dlfcn.h> 37 # include <stdio.h> 38 # include <unistd.h> 39 # include <sys/resource.h> 40 # include <pthread.h> 41 # include <sys/stat.h> 42 # include <sys/time.h> 43 # include <sys/times.h> 44 # include <sys/utsname.h> 45 # include <sys/socket.h> 46 # include <sys/wait.h> 47 # include <pwd.h> 48 # include <poll.h> 49 # include <semaphore.h> 50 # include <fcntl.h> 51 # include <string.h> 52 # include <syscall.h> 53 # include <sys/sysinfo.h> 54 # include <gnu/libc-version.h> 55 # include <sys/ipc.h> 56 # include <sys/shm.h> 57 # include <link.h> 58 # include <stdint.h> 59 # include <inttypes.h> 60 61 #define MAX_PATH (2 * K) 62 63 // for timer info max values which include all bits 64 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 65 #define SEC_IN_NANOSECS 1000000000LL 66 67 //////////////////////////////////////////////////////////////////////////////// 68 // global variables 69 julong os::Linux::_physical_memory = 0; 70 71 address os::Linux::_initial_thread_stack_bottom = NULL; 72 uintptr_t os::Linux::_initial_thread_stack_size = 0; 73 74 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 75 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 76 Mutex* os::Linux::_createThread_lock = NULL; 77 pthread_t os::Linux::_main_thread; 78 int os::Linux::_page_size = -1; 79 bool os::Linux::_is_floating_stack = false; 80 bool os::Linux::_is_NPTL = false; 81 bool os::Linux::_supports_fast_thread_cpu_time = false; 82 const char * os::Linux::_glibc_version = NULL; 83 const char * os::Linux::_libpthread_version = NULL; 84 85 static jlong initial_time_count=0; 86 87 static int clock_tics_per_sec = 100; 88 89 // For diagnostics to print a message once. see run_periodic_checks 90 static sigset_t check_signal_done; 91 static bool check_signals = true;; 92 93 static pid_t _initial_pid = 0; 94 95 /* Signal number used to suspend/resume a thread */ 96 97 /* do not use any signal number less than SIGSEGV, see 4355769 */ 98 static int SR_signum = SIGUSR2; 99 sigset_t SR_sigset; 100 101 /* Used to protect dlsym() calls */ 102 static pthread_mutex_t dl_mutex; 103 104 //////////////////////////////////////////////////////////////////////////////// 105 // utility functions 106 107 static int SR_initialize(); 108 static int SR_finalize(); 109 110 julong os::available_memory() { 111 return Linux::available_memory(); 112 } 113 114 julong os::Linux::available_memory() { 115 // values in struct sysinfo are "unsigned long" 116 struct sysinfo si; 117 sysinfo(&si); 118 119 return (julong)si.freeram * si.mem_unit; 120 } 121 122 julong os::physical_memory() { 123 return Linux::physical_memory(); 124 } 125 126 julong os::allocatable_physical_memory(julong size) { 127 #ifdef _LP64 128 return size; 129 #else 130 julong result = MIN2(size, (julong)3800*M); 131 if (!is_allocatable(result)) { 132 // See comments under solaris for alignment considerations 133 julong reasonable_size = (julong)2*G - 2 * os::vm_page_size(); 134 result = MIN2(size, reasonable_size); 135 } 136 return result; 137 #endif // _LP64 138 } 139 140 //////////////////////////////////////////////////////////////////////////////// 141 // environment support 142 143 bool os::getenv(const char* name, char* buf, int len) { 144 const char* val = ::getenv(name); 145 if (val != NULL && strlen(val) < (size_t)len) { 146 strcpy(buf, val); 147 return true; 148 } 149 if (len > 0) buf[0] = 0; // return a null string 150 return false; 151 } 152 153 154 // Return true if user is running as root. 155 156 bool os::have_special_privileges() { 157 static bool init = false; 158 static bool privileges = false; 159 if (!init) { 160 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 161 init = true; 162 } 163 return privileges; 164 } 165 166 167 #ifndef SYS_gettid 168 // i386: 224, ia64: 1105, amd64: 186, sparc 143 169 #ifdef __ia64__ 170 #define SYS_gettid 1105 171 #elif __i386__ 172 #define SYS_gettid 224 173 #elif __amd64__ 174 #define SYS_gettid 186 175 #elif __sparc__ 176 #define SYS_gettid 143 177 #else 178 #error define gettid for the arch 179 #endif 180 #endif 181 182 // Cpu architecture string 183 #if defined(ZERO) 184 static char cpu_arch[] = ZERO_LIBARCH; 185 #elif defined(IA64) 186 static char cpu_arch[] = "ia64"; 187 #elif defined(IA32) 188 static char cpu_arch[] = "i386"; 189 #elif defined(AMD64) 190 static char cpu_arch[] = "amd64"; 191 #elif defined(SPARC) 192 # ifdef _LP64 193 static char cpu_arch[] = "sparcv9"; 194 # else 195 static char cpu_arch[] = "sparc"; 196 # endif 197 #else 198 #error Add appropriate cpu_arch setting 199 #endif 200 201 202 // pid_t gettid() 203 // 204 // Returns the kernel thread id of the currently running thread. Kernel 205 // thread id is used to access /proc. 206 // 207 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 208 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 209 // 210 pid_t os::Linux::gettid() { 211 int rslt = syscall(SYS_gettid); 212 if (rslt == -1) { 213 // old kernel, no NPTL support 214 return getpid(); 215 } else { 216 return (pid_t)rslt; 217 } 218 } 219 220 // Most versions of linux have a bug where the number of processors are 221 // determined by looking at the /proc file system. In a chroot environment, 222 // the system call returns 1. This causes the VM to act as if it is 223 // a single processor and elide locking (see is_MP() call). 224 static bool unsafe_chroot_detected = false; 225 static const char *unstable_chroot_error = "/proc file system not found.\n" 226 "Java may be unstable running multithreaded in a chroot " 227 "environment on Linux when /proc filesystem is not mounted."; 228 229 void os::Linux::initialize_system_info() { 230 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); 231 if (processor_count() == 1) { 232 pid_t pid = os::Linux::gettid(); 233 char fname[32]; 234 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 235 FILE *fp = fopen(fname, "r"); 236 if (fp == NULL) { 237 unsafe_chroot_detected = true; 238 } else { 239 fclose(fp); 240 } 241 } 242 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 243 assert(processor_count() > 0, "linux error"); 244 } 245 246 void os::init_system_properties_values() { 247 // char arch[12]; 248 // sysinfo(SI_ARCHITECTURE, arch, sizeof(arch)); 249 250 // The next steps are taken in the product version: 251 // 252 // Obtain the JAVA_HOME value from the location of libjvm[_g].so. 253 // This library should be located at: 254 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm[_g].so. 255 // 256 // If "/jre/lib/" appears at the right place in the path, then we 257 // assume libjvm[_g].so is installed in a JDK and we use this path. 258 // 259 // Otherwise exit with message: "Could not create the Java virtual machine." 260 // 261 // The following extra steps are taken in the debugging version: 262 // 263 // If "/jre/lib/" does NOT appear at the right place in the path 264 // instead of exit check for $JAVA_HOME environment variable. 265 // 266 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 267 // then we append a fake suffix "hotspot/libjvm[_g].so" to this path so 268 // it looks like libjvm[_g].so is installed there 269 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm[_g].so. 270 // 271 // Otherwise exit. 272 // 273 // Important note: if the location of libjvm.so changes this 274 // code needs to be changed accordingly. 275 276 // The next few definitions allow the code to be verbatim: 277 #define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n)) 278 #define getenv(n) ::getenv(n) 279 280 /* 281 * See ld(1): 282 * The linker uses the following search paths to locate required 283 * shared libraries: 284 * 1: ... 285 * ... 286 * 7: The default directories, normally /lib and /usr/lib. 287 */ 288 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 289 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 290 #else 291 #define DEFAULT_LIBPATH "/lib:/usr/lib" 292 #endif 293 294 #define EXTENSIONS_DIR "/lib/ext" 295 #define ENDORSED_DIR "/lib/endorsed" 296 #define REG_DIR "/usr/java/packages" 297 298 { 299 /* sysclasspath, java_home, dll_dir */ 300 { 301 char *home_path; 302 char *dll_path; 303 char *pslash; 304 char buf[MAXPATHLEN]; 305 os::jvm_path(buf, sizeof(buf)); 306 307 // Found the full path to libjvm.so. 308 // Now cut the path to <java_home>/jre if we can. 309 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */ 310 pslash = strrchr(buf, '/'); 311 if (pslash != NULL) 312 *pslash = '\0'; /* get rid of /{client|server|hotspot} */ 313 dll_path = malloc(strlen(buf) + 1); 314 if (dll_path == NULL) 315 return; 316 strcpy(dll_path, buf); 317 Arguments::set_dll_dir(dll_path); 318 319 if (pslash != NULL) { 320 pslash = strrchr(buf, '/'); 321 if (pslash != NULL) { 322 *pslash = '\0'; /* get rid of /<arch> */ 323 pslash = strrchr(buf, '/'); 324 if (pslash != NULL) 325 *pslash = '\0'; /* get rid of /lib */ 326 } 327 } 328 329 home_path = malloc(strlen(buf) + 1); 330 if (home_path == NULL) 331 return; 332 strcpy(home_path, buf); 333 Arguments::set_java_home(home_path); 334 335 if (!set_boot_path('/', ':')) 336 return; 337 } 338 339 /* 340 * Where to look for native libraries 341 * 342 * Note: Due to a legacy implementation, most of the library path 343 * is set in the launcher. This was to accomodate linking restrictions 344 * on legacy Linux implementations (which are no longer supported). 345 * Eventually, all the library path setting will be done here. 346 * 347 * However, to prevent the proliferation of improperly built native 348 * libraries, the new path component /usr/java/packages is added here. 349 * Eventually, all the library path setting will be done here. 350 */ 351 { 352 char *ld_library_path; 353 354 /* 355 * Construct the invariant part of ld_library_path. Note that the 356 * space for the colon and the trailing null are provided by the 357 * nulls included by the sizeof operator (so actually we allocate 358 * a byte more than necessary). 359 */ 360 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") + 361 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH)); 362 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch); 363 364 /* 365 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It 366 * should always exist (until the legacy problem cited above is 367 * addressed). 368 */ 369 char *v = getenv("LD_LIBRARY_PATH"); 370 if (v != NULL) { 371 char *t = ld_library_path; 372 /* That's +1 for the colon and +1 for the trailing '\0' */ 373 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1); 374 sprintf(ld_library_path, "%s:%s", v, t); 375 } 376 Arguments::set_library_path(ld_library_path); 377 } 378 379 /* 380 * Extensions directories. 381 * 382 * Note that the space for the colon and the trailing null are provided 383 * by the nulls included by the sizeof operator (so actually one byte more 384 * than necessary is allocated). 385 */ 386 { 387 char *buf = malloc(strlen(Arguments::get_java_home()) + 388 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR)); 389 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR, 390 Arguments::get_java_home()); 391 Arguments::set_ext_dirs(buf); 392 } 393 394 /* Endorsed standards default directory. */ 395 { 396 char * buf; 397 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR)); 398 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 399 Arguments::set_endorsed_dirs(buf); 400 } 401 } 402 403 #undef malloc 404 #undef getenv 405 #undef EXTENSIONS_DIR 406 #undef ENDORSED_DIR 407 408 // Done 409 return; 410 } 411 412 //////////////////////////////////////////////////////////////////////////////// 413 // breakpoint support 414 415 void os::breakpoint() { 416 BREAKPOINT; 417 } 418 419 extern "C" void breakpoint() { 420 // use debugger to set breakpoint here 421 } 422 423 //////////////////////////////////////////////////////////////////////////////// 424 // signal support 425 426 debug_only(static bool signal_sets_initialized = false); 427 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 428 429 bool os::Linux::is_sig_ignored(int sig) { 430 struct sigaction oact; 431 sigaction(sig, (struct sigaction*)NULL, &oact); 432 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 433 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 434 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 435 return true; 436 else 437 return false; 438 } 439 440 void os::Linux::signal_sets_init() { 441 // Should also have an assertion stating we are still single-threaded. 442 assert(!signal_sets_initialized, "Already initialized"); 443 // Fill in signals that are necessarily unblocked for all threads in 444 // the VM. Currently, we unblock the following signals: 445 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 446 // by -Xrs (=ReduceSignalUsage)); 447 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 448 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 449 // the dispositions or masks wrt these signals. 450 // Programs embedding the VM that want to use the above signals for their 451 // own purposes must, at this time, use the "-Xrs" option to prevent 452 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 453 // (See bug 4345157, and other related bugs). 454 // In reality, though, unblocking these signals is really a nop, since 455 // these signals are not blocked by default. 456 sigemptyset(&unblocked_sigs); 457 sigemptyset(&allowdebug_blocked_sigs); 458 sigaddset(&unblocked_sigs, SIGILL); 459 sigaddset(&unblocked_sigs, SIGSEGV); 460 sigaddset(&unblocked_sigs, SIGBUS); 461 sigaddset(&unblocked_sigs, SIGFPE); 462 sigaddset(&unblocked_sigs, SR_signum); 463 464 if (!ReduceSignalUsage) { 465 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 466 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 467 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 468 } 469 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 470 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 471 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 472 } 473 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 474 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 475 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 476 } 477 } 478 // Fill in signals that are blocked by all but the VM thread. 479 sigemptyset(&vm_sigs); 480 if (!ReduceSignalUsage) 481 sigaddset(&vm_sigs, BREAK_SIGNAL); 482 debug_only(signal_sets_initialized = true); 483 484 } 485 486 // These are signals that are unblocked while a thread is running Java. 487 // (For some reason, they get blocked by default.) 488 sigset_t* os::Linux::unblocked_signals() { 489 assert(signal_sets_initialized, "Not initialized"); 490 return &unblocked_sigs; 491 } 492 493 // These are the signals that are blocked while a (non-VM) thread is 494 // running Java. Only the VM thread handles these signals. 495 sigset_t* os::Linux::vm_signals() { 496 assert(signal_sets_initialized, "Not initialized"); 497 return &vm_sigs; 498 } 499 500 // These are signals that are blocked during cond_wait to allow debugger in 501 sigset_t* os::Linux::allowdebug_blocked_signals() { 502 assert(signal_sets_initialized, "Not initialized"); 503 return &allowdebug_blocked_sigs; 504 } 505 506 void os::Linux::hotspot_sigmask(Thread* thread) { 507 508 //Save caller's signal mask before setting VM signal mask 509 sigset_t caller_sigmask; 510 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 511 512 OSThread* osthread = thread->osthread(); 513 osthread->set_caller_sigmask(caller_sigmask); 514 515 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 516 517 if (!ReduceSignalUsage) { 518 if (thread->is_VM_thread()) { 519 // Only the VM thread handles BREAK_SIGNAL ... 520 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 521 } else { 522 // ... all other threads block BREAK_SIGNAL 523 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 524 } 525 } 526 } 527 528 ////////////////////////////////////////////////////////////////////////////// 529 // detecting pthread library 530 531 void os::Linux::libpthread_init() { 532 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 533 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 534 // generic name for earlier versions. 535 // Define macros here so we can build HotSpot on old systems. 536 # ifndef _CS_GNU_LIBC_VERSION 537 # define _CS_GNU_LIBC_VERSION 2 538 # endif 539 # ifndef _CS_GNU_LIBPTHREAD_VERSION 540 # define _CS_GNU_LIBPTHREAD_VERSION 3 541 # endif 542 543 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 544 if (n > 0) { 545 char *str = (char *)malloc(n); 546 confstr(_CS_GNU_LIBC_VERSION, str, n); 547 os::Linux::set_glibc_version(str); 548 } else { 549 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 550 static char _gnu_libc_version[32]; 551 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 552 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 553 os::Linux::set_glibc_version(_gnu_libc_version); 554 } 555 556 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 557 if (n > 0) { 558 char *str = (char *)malloc(n); 559 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 560 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 561 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 562 // is the case. LinuxThreads has a hard limit on max number of threads. 563 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 564 // On the other hand, NPTL does not have such a limit, sysconf() 565 // will return -1 and errno is not changed. Check if it is really NPTL. 566 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 567 strstr(str, "NPTL") && 568 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 569 free(str); 570 os::Linux::set_libpthread_version("linuxthreads"); 571 } else { 572 os::Linux::set_libpthread_version(str); 573 } 574 } else { 575 // glibc before 2.3.2 only has LinuxThreads. 576 os::Linux::set_libpthread_version("linuxthreads"); 577 } 578 579 if (strstr(libpthread_version(), "NPTL")) { 580 os::Linux::set_is_NPTL(); 581 } else { 582 os::Linux::set_is_LinuxThreads(); 583 } 584 585 // LinuxThreads have two flavors: floating-stack mode, which allows variable 586 // stack size; and fixed-stack mode. NPTL is always floating-stack. 587 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 588 os::Linux::set_is_floating_stack(); 589 } 590 } 591 592 ///////////////////////////////////////////////////////////////////////////// 593 // thread stack 594 595 // Force Linux kernel to expand current thread stack. If "bottom" is close 596 // to the stack guard, caller should block all signals. 597 // 598 // MAP_GROWSDOWN: 599 // A special mmap() flag that is used to implement thread stacks. It tells 600 // kernel that the memory region should extend downwards when needed. This 601 // allows early versions of LinuxThreads to only mmap the first few pages 602 // when creating a new thread. Linux kernel will automatically expand thread 603 // stack as needed (on page faults). 604 // 605 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 606 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 607 // region, it's hard to tell if the fault is due to a legitimate stack 608 // access or because of reading/writing non-exist memory (e.g. buffer 609 // overrun). As a rule, if the fault happens below current stack pointer, 610 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 611 // application (see Linux kernel fault.c). 612 // 613 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 614 // stack overflow detection. 615 // 616 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 617 // not use this flag. However, the stack of initial thread is not created 618 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 619 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 620 // and then attach the thread to JVM. 621 // 622 // To get around the problem and allow stack banging on Linux, we need to 623 // manually expand thread stack after receiving the SIGSEGV. 624 // 625 // There are two ways to expand thread stack to address "bottom", we used 626 // both of them in JVM before 1.5: 627 // 1. adjust stack pointer first so that it is below "bottom", and then 628 // touch "bottom" 629 // 2. mmap() the page in question 630 // 631 // Now alternate signal stack is gone, it's harder to use 2. For instance, 632 // if current sp is already near the lower end of page 101, and we need to 633 // call mmap() to map page 100, it is possible that part of the mmap() frame 634 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 635 // That will destroy the mmap() frame and cause VM to crash. 636 // 637 // The following code works by adjusting sp first, then accessing the "bottom" 638 // page to force a page fault. Linux kernel will then automatically expand the 639 // stack mapping. 640 // 641 // _expand_stack_to() assumes its frame size is less than page size, which 642 // should always be true if the function is not inlined. 643 644 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 645 #define NOINLINE 646 #else 647 #define NOINLINE __attribute__ ((noinline)) 648 #endif 649 650 static void _expand_stack_to(address bottom) NOINLINE; 651 652 static void _expand_stack_to(address bottom) { 653 address sp; 654 size_t size; 655 volatile char *p; 656 657 // Adjust bottom to point to the largest address within the same page, it 658 // gives us a one-page buffer if alloca() allocates slightly more memory. 659 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 660 bottom += os::Linux::page_size() - 1; 661 662 // sp might be slightly above current stack pointer; if that's the case, we 663 // will alloca() a little more space than necessary, which is OK. Don't use 664 // os::current_stack_pointer(), as its result can be slightly below current 665 // stack pointer, causing us to not alloca enough to reach "bottom". 666 sp = (address)&sp; 667 668 if (sp > bottom) { 669 size = sp - bottom; 670 p = (volatile char *)alloca(size); 671 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 672 p[0] = '\0'; 673 } 674 } 675 676 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 677 assert(t!=NULL, "just checking"); 678 assert(t->osthread()->expanding_stack(), "expand should be set"); 679 assert(t->stack_base() != NULL, "stack_base was not initialized"); 680 681 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 682 sigset_t mask_all, old_sigset; 683 sigfillset(&mask_all); 684 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 685 _expand_stack_to(addr); 686 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 687 return true; 688 } 689 return false; 690 } 691 692 ////////////////////////////////////////////////////////////////////////////// 693 // create new thread 694 695 static address highest_vm_reserved_address(); 696 697 // check if it's safe to start a new thread 698 static bool _thread_safety_check(Thread* thread) { 699 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 700 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 701 // Heap is mmap'ed at lower end of memory space. Thread stacks are 702 // allocated (MAP_FIXED) from high address space. Every thread stack 703 // occupies a fixed size slot (usually 2Mbytes, but user can change 704 // it to other values if they rebuild LinuxThreads). 705 // 706 // Problem with MAP_FIXED is that mmap() can still succeed even part of 707 // the memory region has already been mmap'ed. That means if we have too 708 // many threads and/or very large heap, eventually thread stack will 709 // collide with heap. 710 // 711 // Here we try to prevent heap/stack collision by comparing current 712 // stack bottom with the highest address that has been mmap'ed by JVM 713 // plus a safety margin for memory maps created by native code. 714 // 715 // This feature can be disabled by setting ThreadSafetyMargin to 0 716 // 717 if (ThreadSafetyMargin > 0) { 718 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 719 720 // not safe if our stack extends below the safety margin 721 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 722 } else { 723 return true; 724 } 725 } else { 726 // Floating stack LinuxThreads or NPTL: 727 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 728 // there's not enough space left, pthread_create() will fail. If we come 729 // here, that means enough space has been reserved for stack. 730 return true; 731 } 732 } 733 734 // Thread start routine for all newly created threads 735 static void *java_start(Thread *thread) { 736 // Try to randomize the cache line index of hot stack frames. 737 // This helps when threads of the same stack traces evict each other's 738 // cache lines. The threads can be either from the same JVM instance, or 739 // from different JVM instances. The benefit is especially true for 740 // processors with hyperthreading technology. 741 static int counter = 0; 742 int pid = os::current_process_id(); 743 alloca(((pid ^ counter++) & 7) * 128); 744 745 ThreadLocalStorage::set_thread(thread); 746 747 OSThread* osthread = thread->osthread(); 748 Monitor* sync = osthread->startThread_lock(); 749 750 // non floating stack LinuxThreads needs extra check, see above 751 if (!_thread_safety_check(thread)) { 752 // notify parent thread 753 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 754 osthread->set_state(ZOMBIE); 755 sync->notify_all(); 756 return NULL; 757 } 758 759 // thread_id is kernel thread id (similar to Solaris LWP id) 760 osthread->set_thread_id(os::Linux::gettid()); 761 762 if (UseNUMA) { 763 int lgrp_id = os::numa_get_group_id(); 764 if (lgrp_id != -1) { 765 thread->set_lgrp_id(lgrp_id); 766 } 767 } 768 // initialize signal mask for this thread 769 os::Linux::hotspot_sigmask(thread); 770 771 // initialize floating point control register 772 os::Linux::init_thread_fpu_state(); 773 774 // handshaking with parent thread 775 { 776 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 777 778 // notify parent thread 779 osthread->set_state(INITIALIZED); 780 sync->notify_all(); 781 782 // wait until os::start_thread() 783 while (osthread->get_state() == INITIALIZED) { 784 sync->wait(Mutex::_no_safepoint_check_flag); 785 } 786 } 787 788 // call one more level start routine 789 thread->run(); 790 791 return 0; 792 } 793 794 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 795 assert(thread->osthread() == NULL, "caller responsible"); 796 797 // Allocate the OSThread object 798 OSThread* osthread = new OSThread(NULL, NULL); 799 if (osthread == NULL) { 800 return false; 801 } 802 803 // set the correct thread state 804 osthread->set_thread_type(thr_type); 805 806 // Initial state is ALLOCATED but not INITIALIZED 807 osthread->set_state(ALLOCATED); 808 809 thread->set_osthread(osthread); 810 811 // init thread attributes 812 pthread_attr_t attr; 813 pthread_attr_init(&attr); 814 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 815 816 // stack size 817 if (os::Linux::supports_variable_stack_size()) { 818 // calculate stack size if it's not specified by caller 819 if (stack_size == 0) { 820 stack_size = os::Linux::default_stack_size(thr_type); 821 822 switch (thr_type) { 823 case os::java_thread: 824 // Java threads use ThreadStackSize which default value can be changed with the flag -Xss 825 if (JavaThread::stack_size_at_create() > 0) stack_size = JavaThread::stack_size_at_create(); 826 break; 827 case os::compiler_thread: 828 if (CompilerThreadStackSize > 0) { 829 stack_size = (size_t)(CompilerThreadStackSize * K); 830 break; 831 } // else fall through: 832 // use VMThreadStackSize if CompilerThreadStackSize is not defined 833 case os::vm_thread: 834 case os::pgc_thread: 835 case os::cgc_thread: 836 case os::watcher_thread: 837 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 838 break; 839 } 840 } 841 842 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 843 pthread_attr_setstacksize(&attr, stack_size); 844 } else { 845 // let pthread_create() pick the default value. 846 } 847 848 // glibc guard page 849 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 850 851 ThreadState state; 852 853 { 854 // Serialize thread creation if we are running with fixed stack LinuxThreads 855 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 856 if (lock) { 857 os::Linux::createThread_lock()->lock_without_safepoint_check(); 858 } 859 860 pthread_t tid; 861 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 862 863 pthread_attr_destroy(&attr); 864 865 if (ret != 0) { 866 if (PrintMiscellaneous && (Verbose || WizardMode)) { 867 perror("pthread_create()"); 868 } 869 // Need to clean up stuff we've allocated so far 870 thread->set_osthread(NULL); 871 delete osthread; 872 if (lock) os::Linux::createThread_lock()->unlock(); 873 return false; 874 } 875 876 // Store pthread info into the OSThread 877 osthread->set_pthread_id(tid); 878 879 // Wait until child thread is either initialized or aborted 880 { 881 Monitor* sync_with_child = osthread->startThread_lock(); 882 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 883 while ((state = osthread->get_state()) == ALLOCATED) { 884 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 885 } 886 } 887 888 if (lock) { 889 os::Linux::createThread_lock()->unlock(); 890 } 891 } 892 893 // Aborted due to thread limit being reached 894 if (state == ZOMBIE) { 895 thread->set_osthread(NULL); 896 delete osthread; 897 return false; 898 } 899 900 // The thread is returned suspended (in state INITIALIZED), 901 // and is started higher up in the call chain 902 assert(state == INITIALIZED, "race condition"); 903 return true; 904 } 905 906 ///////////////////////////////////////////////////////////////////////////// 907 // attach existing thread 908 909 // bootstrap the main thread 910 bool os::create_main_thread(JavaThread* thread) { 911 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 912 return create_attached_thread(thread); 913 } 914 915 bool os::create_attached_thread(JavaThread* thread) { 916 #ifdef ASSERT 917 thread->verify_not_published(); 918 #endif 919 920 // Allocate the OSThread object 921 OSThread* osthread = new OSThread(NULL, NULL); 922 923 if (osthread == NULL) { 924 return false; 925 } 926 927 // Store pthread info into the OSThread 928 osthread->set_thread_id(os::Linux::gettid()); 929 osthread->set_pthread_id(::pthread_self()); 930 931 // initialize floating point control register 932 os::Linux::init_thread_fpu_state(); 933 934 // Initial thread state is RUNNABLE 935 osthread->set_state(RUNNABLE); 936 937 thread->set_osthread(osthread); 938 939 if (UseNUMA) { 940 int lgrp_id = os::numa_get_group_id(); 941 if (lgrp_id != -1) { 942 thread->set_lgrp_id(lgrp_id); 943 } 944 } 945 946 if (os::Linux::is_initial_thread()) { 947 // If current thread is initial thread, its stack is mapped on demand, 948 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 949 // the entire stack region to avoid SEGV in stack banging. 950 // It is also useful to get around the heap-stack-gap problem on SuSE 951 // kernel (see 4821821 for details). We first expand stack to the top 952 // of yellow zone, then enable stack yellow zone (order is significant, 953 // enabling yellow zone first will crash JVM on SuSE Linux), so there 954 // is no gap between the last two virtual memory regions. 955 956 JavaThread *jt = (JavaThread *)thread; 957 address addr = jt->stack_yellow_zone_base(); 958 assert(addr != NULL, "initialization problem?"); 959 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 960 961 osthread->set_expanding_stack(); 962 os::Linux::manually_expand_stack(jt, addr); 963 osthread->clear_expanding_stack(); 964 } 965 966 // initialize signal mask for this thread 967 // and save the caller's signal mask 968 os::Linux::hotspot_sigmask(thread); 969 970 return true; 971 } 972 973 void os::pd_start_thread(Thread* thread) { 974 OSThread * osthread = thread->osthread(); 975 assert(osthread->get_state() != INITIALIZED, "just checking"); 976 Monitor* sync_with_child = osthread->startThread_lock(); 977 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 978 sync_with_child->notify(); 979 } 980 981 // Free Linux resources related to the OSThread 982 void os::free_thread(OSThread* osthread) { 983 assert(osthread != NULL, "osthread not set"); 984 985 if (Thread::current()->osthread() == osthread) { 986 // Restore caller's signal mask 987 sigset_t sigmask = osthread->caller_sigmask(); 988 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 989 } 990 991 delete osthread; 992 } 993 994 ////////////////////////////////////////////////////////////////////////////// 995 // thread local storage 996 997 int os::allocate_thread_local_storage() { 998 pthread_key_t key; 999 int rslt = pthread_key_create(&key, NULL); 1000 assert(rslt == 0, "cannot allocate thread local storage"); 1001 return (int)key; 1002 } 1003 1004 // Note: This is currently not used by VM, as we don't destroy TLS key 1005 // on VM exit. 1006 void os::free_thread_local_storage(int index) { 1007 int rslt = pthread_key_delete((pthread_key_t)index); 1008 assert(rslt == 0, "invalid index"); 1009 } 1010 1011 void os::thread_local_storage_at_put(int index, void* value) { 1012 int rslt = pthread_setspecific((pthread_key_t)index, value); 1013 assert(rslt == 0, "pthread_setspecific failed"); 1014 } 1015 1016 extern "C" Thread* get_thread() { 1017 return ThreadLocalStorage::thread(); 1018 } 1019 1020 ////////////////////////////////////////////////////////////////////////////// 1021 // initial thread 1022 1023 // Check if current thread is the initial thread, similar to Solaris thr_main. 1024 bool os::Linux::is_initial_thread(void) { 1025 char dummy; 1026 // If called before init complete, thread stack bottom will be null. 1027 // Can be called if fatal error occurs before initialization. 1028 if (initial_thread_stack_bottom() == NULL) return false; 1029 assert(initial_thread_stack_bottom() != NULL && 1030 initial_thread_stack_size() != 0, 1031 "os::init did not locate initial thread's stack region"); 1032 if ((address)&dummy >= initial_thread_stack_bottom() && 1033 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1034 return true; 1035 else return false; 1036 } 1037 1038 // Find the virtual memory area that contains addr 1039 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1040 FILE *fp = fopen("/proc/self/maps", "r"); 1041 if (fp) { 1042 address low, high; 1043 while (!feof(fp)) { 1044 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1045 if (low <= addr && addr < high) { 1046 if (vma_low) *vma_low = low; 1047 if (vma_high) *vma_high = high; 1048 fclose (fp); 1049 return true; 1050 } 1051 } 1052 for (;;) { 1053 int ch = fgetc(fp); 1054 if (ch == EOF || ch == (int)'\n') break; 1055 } 1056 } 1057 fclose(fp); 1058 } 1059 return false; 1060 } 1061 1062 // Locate initial thread stack. This special handling of initial thread stack 1063 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1064 // bogus value for initial thread. 1065 void os::Linux::capture_initial_stack(size_t max_size) { 1066 // stack size is the easy part, get it from RLIMIT_STACK 1067 size_t stack_size; 1068 struct rlimit rlim; 1069 getrlimit(RLIMIT_STACK, &rlim); 1070 stack_size = rlim.rlim_cur; 1071 1072 // 6308388: a bug in ld.so will relocate its own .data section to the 1073 // lower end of primordial stack; reduce ulimit -s value a little bit 1074 // so we won't install guard page on ld.so's data section. 1075 stack_size -= 2 * page_size(); 1076 1077 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1078 // 7.1, in both cases we will get 2G in return value. 1079 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1080 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1081 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1082 // in case other parts in glibc still assumes 2M max stack size. 1083 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1084 #ifndef IA64 1085 if (stack_size > 2 * K * K) stack_size = 2 * K * K; 1086 #else 1087 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1088 if (stack_size > 4 * K * K) stack_size = 4 * K * K; 1089 #endif 1090 1091 // Try to figure out where the stack base (top) is. This is harder. 1092 // 1093 // When an application is started, glibc saves the initial stack pointer in 1094 // a global variable "__libc_stack_end", which is then used by system 1095 // libraries. __libc_stack_end should be pretty close to stack top. The 1096 // variable is available since the very early days. However, because it is 1097 // a private interface, it could disappear in the future. 1098 // 1099 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1100 // to __libc_stack_end, it is very close to stack top, but isn't the real 1101 // stack top. Note that /proc may not exist if VM is running as a chroot 1102 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1103 // /proc/<pid>/stat could change in the future (though unlikely). 1104 // 1105 // We try __libc_stack_end first. If that doesn't work, look for 1106 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1107 // as a hint, which should work well in most cases. 1108 1109 uintptr_t stack_start; 1110 1111 // try __libc_stack_end first 1112 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1113 if (p && *p) { 1114 stack_start = *p; 1115 } else { 1116 // see if we can get the start_stack field from /proc/self/stat 1117 FILE *fp; 1118 int pid; 1119 char state; 1120 int ppid; 1121 int pgrp; 1122 int session; 1123 int nr; 1124 int tpgrp; 1125 unsigned long flags; 1126 unsigned long minflt; 1127 unsigned long cminflt; 1128 unsigned long majflt; 1129 unsigned long cmajflt; 1130 unsigned long utime; 1131 unsigned long stime; 1132 long cutime; 1133 long cstime; 1134 long prio; 1135 long nice; 1136 long junk; 1137 long it_real; 1138 uintptr_t start; 1139 uintptr_t vsize; 1140 uintptr_t rss; 1141 unsigned long rsslim; 1142 uintptr_t scodes; 1143 uintptr_t ecode; 1144 int i; 1145 1146 // Figure what the primordial thread stack base is. Code is inspired 1147 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1148 // followed by command name surrounded by parentheses, state, etc. 1149 char stat[2048]; 1150 int statlen; 1151 1152 fp = fopen("/proc/self/stat", "r"); 1153 if (fp) { 1154 statlen = fread(stat, 1, 2047, fp); 1155 stat[statlen] = '\0'; 1156 fclose(fp); 1157 1158 // Skip pid and the command string. Note that we could be dealing with 1159 // weird command names, e.g. user could decide to rename java launcher 1160 // to "java 1.4.2 :)", then the stat file would look like 1161 // 1234 (java 1.4.2 :)) R ... ... 1162 // We don't really need to know the command string, just find the last 1163 // occurrence of ")" and then start parsing from there. See bug 4726580. 1164 char * s = strrchr(stat, ')'); 1165 1166 i = 0; 1167 if (s) { 1168 // Skip blank chars 1169 do s++; while (isspace(*s)); 1170 1171 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1172 /* 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 */ 1173 i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld " 1174 UINTX_FORMAT UINTX_FORMAT UINTX_FORMAT 1175 " %lu " 1176 UINTX_FORMAT UINTX_FORMAT UINTX_FORMAT, 1177 &state, /* 3 %c */ 1178 &ppid, /* 4 %d */ 1179 &pgrp, /* 5 %d */ 1180 &session, /* 6 %d */ 1181 &nr, /* 7 %d */ 1182 &tpgrp, /* 8 %d */ 1183 &flags, /* 9 %lu */ 1184 &minflt, /* 10 %lu */ 1185 &cminflt, /* 11 %lu */ 1186 &majflt, /* 12 %lu */ 1187 &cmajflt, /* 13 %lu */ 1188 &utime, /* 14 %lu */ 1189 &stime, /* 15 %lu */ 1190 &cutime, /* 16 %ld */ 1191 &cstime, /* 17 %ld */ 1192 &prio, /* 18 %ld */ 1193 &nice, /* 19 %ld */ 1194 &junk, /* 20 %ld */ 1195 &it_real, /* 21 %ld */ 1196 &start, /* 22 UINTX_FORMAT */ 1197 &vsize, /* 23 UINTX_FORMAT */ 1198 &rss, /* 24 UINTX_FORMAT */ 1199 &rsslim, /* 25 %lu */ 1200 &scodes, /* 26 UINTX_FORMAT */ 1201 &ecode, /* 27 UINTX_FORMAT */ 1202 &stack_start); /* 28 UINTX_FORMAT */ 1203 } 1204 1205 if (i != 28 - 2) { 1206 assert(false, "Bad conversion from /proc/self/stat"); 1207 // product mode - assume we are the initial thread, good luck in the 1208 // embedded case. 1209 warning("Can't detect initial thread stack location - bad conversion"); 1210 stack_start = (uintptr_t) &rlim; 1211 } 1212 } else { 1213 // For some reason we can't open /proc/self/stat (for example, running on 1214 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1215 // most cases, so don't abort: 1216 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1217 stack_start = (uintptr_t) &rlim; 1218 } 1219 } 1220 1221 // Now we have a pointer (stack_start) very close to the stack top, the 1222 // next thing to do is to figure out the exact location of stack top. We 1223 // can find out the virtual memory area that contains stack_start by 1224 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1225 // and its upper limit is the real stack top. (again, this would fail if 1226 // running inside chroot, because /proc may not exist.) 1227 1228 uintptr_t stack_top; 1229 address low, high; 1230 if (find_vma((address)stack_start, &low, &high)) { 1231 // success, "high" is the true stack top. (ignore "low", because initial 1232 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1233 stack_top = (uintptr_t)high; 1234 } else { 1235 // failed, likely because /proc/self/maps does not exist 1236 warning("Can't detect initial thread stack location - find_vma failed"); 1237 // best effort: stack_start is normally within a few pages below the real 1238 // stack top, use it as stack top, and reduce stack size so we won't put 1239 // guard page outside stack. 1240 stack_top = stack_start; 1241 stack_size -= 16 * page_size(); 1242 } 1243 1244 // stack_top could be partially down the page so align it 1245 stack_top = align_size_up(stack_top, page_size()); 1246 1247 if (max_size && stack_size > max_size) { 1248 _initial_thread_stack_size = max_size; 1249 } else { 1250 _initial_thread_stack_size = stack_size; 1251 } 1252 1253 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1254 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1255 } 1256 1257 //////////////////////////////////////////////////////////////////////////////// 1258 // time support 1259 1260 // Time since start-up in seconds to a fine granularity. 1261 // Used by VMSelfDestructTimer and the MemProfiler. 1262 double os::elapsedTime() { 1263 1264 return (double)(os::elapsed_counter()) * 0.000001; 1265 } 1266 1267 jlong os::elapsed_counter() { 1268 timeval time; 1269 int status = gettimeofday(&time, NULL); 1270 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count; 1271 } 1272 1273 jlong os::elapsed_frequency() { 1274 return (1000 * 1000); 1275 } 1276 1277 // For now, we say that linux does not support vtime. I have no idea 1278 // whether it can actually be made to (DLD, 9/13/05). 1279 1280 bool os::supports_vtime() { return false; } 1281 bool os::enable_vtime() { return false; } 1282 bool os::vtime_enabled() { return false; } 1283 double os::elapsedVTime() { 1284 // better than nothing, but not much 1285 return elapsedTime(); 1286 } 1287 1288 jlong os::javaTimeMillis() { 1289 timeval time; 1290 int status = gettimeofday(&time, NULL); 1291 assert(status != -1, "linux error"); 1292 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1293 } 1294 1295 #ifndef CLOCK_MONOTONIC 1296 #define CLOCK_MONOTONIC (1) 1297 #endif 1298 1299 void os::Linux::clock_init() { 1300 // we do dlopen's in this particular order due to bug in linux 1301 // dynamical loader (see 6348968) leading to crash on exit 1302 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1303 if (handle == NULL) { 1304 handle = dlopen("librt.so", RTLD_LAZY); 1305 } 1306 1307 if (handle) { 1308 int (*clock_getres_func)(clockid_t, struct timespec*) = 1309 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1310 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1311 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1312 if (clock_getres_func && clock_gettime_func) { 1313 // See if monotonic clock is supported by the kernel. Note that some 1314 // early implementations simply return kernel jiffies (updated every 1315 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1316 // for nano time (though the monotonic property is still nice to have). 1317 // It's fixed in newer kernels, however clock_getres() still returns 1318 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1319 // resolution for now. Hopefully as people move to new kernels, this 1320 // won't be a problem. 1321 struct timespec res; 1322 struct timespec tp; 1323 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1324 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1325 // yes, monotonic clock is supported 1326 _clock_gettime = clock_gettime_func; 1327 } else { 1328 // close librt if there is no monotonic clock 1329 dlclose(handle); 1330 } 1331 } 1332 } 1333 } 1334 1335 #ifndef SYS_clock_getres 1336 1337 #if defined(IA32) || defined(AMD64) 1338 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1339 #else 1340 #error Value of SYS_clock_getres not known on this platform 1341 #endif 1342 1343 #endif 1344 1345 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1346 1347 void os::Linux::fast_thread_clock_init() { 1348 if (!UseLinuxPosixThreadCPUClocks) { 1349 return; 1350 } 1351 clockid_t clockid; 1352 struct timespec tp; 1353 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1354 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1355 1356 // Switch to using fast clocks for thread cpu time if 1357 // the sys_clock_getres() returns 0 error code. 1358 // Note, that some kernels may support the current thread 1359 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1360 // returned by the pthread_getcpuclockid(). 1361 // If the fast Posix clocks are supported then the sys_clock_getres() 1362 // must return at least tp.tv_sec == 0 which means a resolution 1363 // better than 1 sec. This is extra check for reliability. 1364 1365 if(pthread_getcpuclockid_func && 1366 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1367 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1368 1369 _supports_fast_thread_cpu_time = true; 1370 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1371 } 1372 } 1373 1374 jlong os::javaTimeNanos() { 1375 if (Linux::supports_monotonic_clock()) { 1376 struct timespec tp; 1377 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1378 assert(status == 0, "gettime error"); 1379 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1380 return result; 1381 } else { 1382 timeval time; 1383 int status = gettimeofday(&time, NULL); 1384 assert(status != -1, "linux error"); 1385 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1386 return 1000 * usecs; 1387 } 1388 } 1389 1390 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1391 if (Linux::supports_monotonic_clock()) { 1392 info_ptr->max_value = ALL_64_BITS; 1393 1394 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1395 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1396 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1397 } else { 1398 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1399 info_ptr->max_value = ALL_64_BITS; 1400 1401 // gettimeofday is a real time clock so it skips 1402 info_ptr->may_skip_backward = true; 1403 info_ptr->may_skip_forward = true; 1404 } 1405 1406 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1407 } 1408 1409 // Return the real, user, and system times in seconds from an 1410 // arbitrary fixed point in the past. 1411 bool os::getTimesSecs(double* process_real_time, 1412 double* process_user_time, 1413 double* process_system_time) { 1414 struct tms ticks; 1415 clock_t real_ticks = times(&ticks); 1416 1417 if (real_ticks == (clock_t) (-1)) { 1418 return false; 1419 } else { 1420 double ticks_per_second = (double) clock_tics_per_sec; 1421 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1422 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1423 *process_real_time = ((double) real_ticks) / ticks_per_second; 1424 1425 return true; 1426 } 1427 } 1428 1429 1430 char * os::local_time_string(char *buf, size_t buflen) { 1431 struct tm t; 1432 time_t long_time; 1433 time(&long_time); 1434 localtime_r(&long_time, &t); 1435 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1436 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1437 t.tm_hour, t.tm_min, t.tm_sec); 1438 return buf; 1439 } 1440 1441 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1442 return localtime_r(clock, res); 1443 } 1444 1445 //////////////////////////////////////////////////////////////////////////////// 1446 // runtime exit support 1447 1448 // Note: os::shutdown() might be called very early during initialization, or 1449 // called from signal handler. Before adding something to os::shutdown(), make 1450 // sure it is async-safe and can handle partially initialized VM. 1451 void os::shutdown() { 1452 1453 // allow PerfMemory to attempt cleanup of any persistent resources 1454 perfMemory_exit(); 1455 1456 // needs to remove object in file system 1457 AttachListener::abort(); 1458 1459 // flush buffered output, finish log files 1460 ostream_abort(); 1461 1462 // Check for abort hook 1463 abort_hook_t abort_hook = Arguments::abort_hook(); 1464 if (abort_hook != NULL) { 1465 abort_hook(); 1466 } 1467 1468 } 1469 1470 // Note: os::abort() might be called very early during initialization, or 1471 // called from signal handler. Before adding something to os::abort(), make 1472 // sure it is async-safe and can handle partially initialized VM. 1473 void os::abort(bool dump_core) { 1474 os::shutdown(); 1475 if (dump_core) { 1476 #ifndef PRODUCT 1477 fdStream out(defaultStream::output_fd()); 1478 out.print_raw("Current thread is "); 1479 char buf[16]; 1480 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1481 out.print_raw_cr(buf); 1482 out.print_raw_cr("Dumping core ..."); 1483 #endif 1484 ::abort(); // dump core 1485 } 1486 1487 ::exit(1); 1488 } 1489 1490 // Die immediately, no exit hook, no abort hook, no cleanup. 1491 void os::die() { 1492 // _exit() on LinuxThreads only kills current thread 1493 ::abort(); 1494 } 1495 1496 // unused on linux for now. 1497 void os::set_error_file(const char *logfile) {} 1498 1499 intx os::current_thread_id() { return (intx)pthread_self(); } 1500 int os::current_process_id() { 1501 1502 // Under the old linux thread library, linux gives each thread 1503 // its own process id. Because of this each thread will return 1504 // a different pid if this method were to return the result 1505 // of getpid(2). Linux provides no api that returns the pid 1506 // of the launcher thread for the vm. This implementation 1507 // returns a unique pid, the pid of the launcher thread 1508 // that starts the vm 'process'. 1509 1510 // Under the NPTL, getpid() returns the same pid as the 1511 // launcher thread rather than a unique pid per thread. 1512 // Use gettid() if you want the old pre NPTL behaviour. 1513 1514 // if you are looking for the result of a call to getpid() that 1515 // returns a unique pid for the calling thread, then look at the 1516 // OSThread::thread_id() method in osThread_linux.hpp file 1517 1518 return (int)(_initial_pid ? _initial_pid : getpid()); 1519 } 1520 1521 // DLL functions 1522 1523 const char* os::dll_file_extension() { return ".so"; } 1524 1525 const char* os::get_temp_directory() { 1526 const char *prop = Arguments::get_property("java.io.tmpdir"); 1527 return prop == NULL ? "/tmp" : prop; 1528 } 1529 1530 static bool file_exists(const char* filename) { 1531 struct stat statbuf; 1532 if (filename == NULL || strlen(filename) == 0) { 1533 return false; 1534 } 1535 return os::stat(filename, &statbuf) == 0; 1536 } 1537 1538 void os::dll_build_name(char* buffer, size_t buflen, 1539 const char* pname, const char* fname) { 1540 // Copied from libhpi 1541 const size_t pnamelen = pname ? strlen(pname) : 0; 1542 1543 // Quietly truncate on buffer overflow. Should be an error. 1544 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1545 *buffer = '\0'; 1546 return; 1547 } 1548 1549 if (pnamelen == 0) { 1550 snprintf(buffer, buflen, "lib%s.so", fname); 1551 } else if (strchr(pname, *os::path_separator()) != NULL) { 1552 int n; 1553 char** pelements = split_path(pname, &n); 1554 for (int i = 0 ; i < n ; i++) { 1555 // Really shouldn't be NULL, but check can't hurt 1556 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1557 continue; // skip the empty path values 1558 } 1559 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1560 if (file_exists(buffer)) { 1561 break; 1562 } 1563 } 1564 // release the storage 1565 for (int i = 0 ; i < n ; i++) { 1566 if (pelements[i] != NULL) { 1567 FREE_C_HEAP_ARRAY(char, pelements[i]); 1568 } 1569 } 1570 if (pelements != NULL) { 1571 FREE_C_HEAP_ARRAY(char*, pelements); 1572 } 1573 } else { 1574 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1575 } 1576 } 1577 1578 const char* os::get_current_directory(char *buf, int buflen) { 1579 return getcwd(buf, buflen); 1580 } 1581 1582 // check if addr is inside libjvm[_g].so 1583 bool os::address_is_in_vm(address addr) { 1584 static address libjvm_base_addr; 1585 Dl_info dlinfo; 1586 1587 if (libjvm_base_addr == NULL) { 1588 dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo); 1589 libjvm_base_addr = (address)dlinfo.dli_fbase; 1590 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1591 } 1592 1593 if (dladdr((void *)addr, &dlinfo)) { 1594 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1595 } 1596 1597 return false; 1598 } 1599 1600 bool os::dll_address_to_function_name(address addr, char *buf, 1601 int buflen, int *offset) { 1602 Dl_info dlinfo; 1603 1604 if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) { 1605 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1606 if (offset) *offset = addr - (address)dlinfo.dli_saddr; 1607 return true; 1608 } else { 1609 if (buf) buf[0] = '\0'; 1610 if (offset) *offset = -1; 1611 return false; 1612 } 1613 } 1614 1615 struct _address_to_library_name { 1616 address addr; // input : memory address 1617 size_t buflen; // size of fname 1618 char* fname; // output: library name 1619 address base; // library base addr 1620 }; 1621 1622 static int address_to_library_name_callback(struct dl_phdr_info *info, 1623 size_t size, void *data) { 1624 int i; 1625 bool found = false; 1626 address libbase = NULL; 1627 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1628 1629 // iterate through all loadable segments 1630 for (i = 0; i < info->dlpi_phnum; i++) { 1631 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1632 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1633 // base address of a library is the lowest address of its loaded 1634 // segments. 1635 if (libbase == NULL || libbase > segbase) { 1636 libbase = segbase; 1637 } 1638 // see if 'addr' is within current segment 1639 if (segbase <= d->addr && 1640 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1641 found = true; 1642 } 1643 } 1644 } 1645 1646 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1647 // so dll_address_to_library_name() can fall through to use dladdr() which 1648 // can figure out executable name from argv[0]. 1649 if (found && info->dlpi_name && info->dlpi_name[0]) { 1650 d->base = libbase; 1651 if (d->fname) { 1652 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1653 } 1654 return 1; 1655 } 1656 return 0; 1657 } 1658 1659 bool os::dll_address_to_library_name(address addr, char* buf, 1660 int buflen, int* offset) { 1661 Dl_info dlinfo; 1662 struct _address_to_library_name data; 1663 1664 // There is a bug in old glibc dladdr() implementation that it could resolve 1665 // to wrong library name if the .so file has a base address != NULL. Here 1666 // we iterate through the program headers of all loaded libraries to find 1667 // out which library 'addr' really belongs to. This workaround can be 1668 // removed once the minimum requirement for glibc is moved to 2.3.x. 1669 data.addr = addr; 1670 data.fname = buf; 1671 data.buflen = buflen; 1672 data.base = NULL; 1673 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1674 1675 if (rslt) { 1676 // buf already contains library name 1677 if (offset) *offset = addr - data.base; 1678 return true; 1679 } else if (dladdr((void*)addr, &dlinfo)){ 1680 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1681 if (offset) *offset = addr - (address)dlinfo.dli_fbase; 1682 return true; 1683 } else { 1684 if (buf) buf[0] = '\0'; 1685 if (offset) *offset = -1; 1686 return false; 1687 } 1688 } 1689 1690 // Loads .dll/.so and 1691 // in case of error it checks if .dll/.so was built for the 1692 // same architecture as Hotspot is running on 1693 1694 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1695 { 1696 void * result= ::dlopen(filename, RTLD_LAZY); 1697 if (result != NULL) { 1698 // Successful loading 1699 return result; 1700 } 1701 1702 Elf32_Ehdr elf_head; 1703 1704 // Read system error message into ebuf 1705 // It may or may not be overwritten below 1706 ::strncpy(ebuf, ::dlerror(), ebuflen-1); 1707 ebuf[ebuflen-1]='\0'; 1708 int diag_msg_max_length=ebuflen-strlen(ebuf); 1709 char* diag_msg_buf=ebuf+strlen(ebuf); 1710 1711 if (diag_msg_max_length==0) { 1712 // No more space in ebuf for additional diagnostics message 1713 return NULL; 1714 } 1715 1716 1717 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1718 1719 if (file_descriptor < 0) { 1720 // Can't open library, report dlerror() message 1721 return NULL; 1722 } 1723 1724 bool failed_to_read_elf_head= 1725 (sizeof(elf_head)!= 1726 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1727 1728 ::close(file_descriptor); 1729 if (failed_to_read_elf_head) { 1730 // file i/o error - report dlerror() msg 1731 return NULL; 1732 } 1733 1734 typedef struct { 1735 Elf32_Half code; // Actual value as defined in elf.h 1736 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1737 char elf_class; // 32 or 64 bit 1738 char endianess; // MSB or LSB 1739 char* name; // String representation 1740 } arch_t; 1741 1742 #ifndef EM_486 1743 #define EM_486 6 /* Intel 80486 */ 1744 #endif 1745 1746 static const arch_t arch_array[]={ 1747 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1748 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1749 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1750 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1751 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1752 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1753 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1754 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1755 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1756 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1757 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1758 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1759 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1760 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1761 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1762 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1763 }; 1764 1765 #if (defined IA32) 1766 static Elf32_Half running_arch_code=EM_386; 1767 #elif (defined AMD64) 1768 static Elf32_Half running_arch_code=EM_X86_64; 1769 #elif (defined IA64) 1770 static Elf32_Half running_arch_code=EM_IA_64; 1771 #elif (defined __sparc) && (defined _LP64) 1772 static Elf32_Half running_arch_code=EM_SPARCV9; 1773 #elif (defined __sparc) && (!defined _LP64) 1774 static Elf32_Half running_arch_code=EM_SPARC; 1775 #elif (defined __powerpc64__) 1776 static Elf32_Half running_arch_code=EM_PPC64; 1777 #elif (defined __powerpc__) 1778 static Elf32_Half running_arch_code=EM_PPC; 1779 #elif (defined ARM) 1780 static Elf32_Half running_arch_code=EM_ARM; 1781 #elif (defined S390) 1782 static Elf32_Half running_arch_code=EM_S390; 1783 #elif (defined ALPHA) 1784 static Elf32_Half running_arch_code=EM_ALPHA; 1785 #elif (defined MIPSEL) 1786 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1787 #elif (defined PARISC) 1788 static Elf32_Half running_arch_code=EM_PARISC; 1789 #elif (defined MIPS) 1790 static Elf32_Half running_arch_code=EM_MIPS; 1791 #elif (defined M68K) 1792 static Elf32_Half running_arch_code=EM_68K; 1793 #else 1794 #error Method os::dll_load requires that one of following is defined:\ 1795 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1796 #endif 1797 1798 // Identify compatability class for VM's architecture and library's architecture 1799 // Obtain string descriptions for architectures 1800 1801 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1802 int running_arch_index=-1; 1803 1804 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 1805 if (running_arch_code == arch_array[i].code) { 1806 running_arch_index = i; 1807 } 1808 if (lib_arch.code == arch_array[i].code) { 1809 lib_arch.compat_class = arch_array[i].compat_class; 1810 lib_arch.name = arch_array[i].name; 1811 } 1812 } 1813 1814 assert(running_arch_index != -1, 1815 "Didn't find running architecture code (running_arch_code) in arch_array"); 1816 if (running_arch_index == -1) { 1817 // Even though running architecture detection failed 1818 // we may still continue with reporting dlerror() message 1819 return NULL; 1820 } 1821 1822 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1823 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1824 return NULL; 1825 } 1826 1827 #ifndef S390 1828 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 1829 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 1830 return NULL; 1831 } 1832 #endif // !S390 1833 1834 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 1835 if ( lib_arch.name!=NULL ) { 1836 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1837 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 1838 lib_arch.name, arch_array[running_arch_index].name); 1839 } else { 1840 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1841 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 1842 lib_arch.code, 1843 arch_array[running_arch_index].name); 1844 } 1845 } 1846 1847 return NULL; 1848 } 1849 1850 /* 1851 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 1852 * chances are you might want to run the generated bits against glibc-2.0 1853 * libdl.so, so always use locking for any version of glibc. 1854 */ 1855 void* os::dll_lookup(void* handle, const char* name) { 1856 pthread_mutex_lock(&dl_mutex); 1857 void* res = dlsym(handle, name); 1858 pthread_mutex_unlock(&dl_mutex); 1859 return res; 1860 } 1861 1862 1863 bool _print_ascii_file(const char* filename, outputStream* st) { 1864 int fd = open(filename, O_RDONLY); 1865 if (fd == -1) { 1866 return false; 1867 } 1868 1869 char buf[32]; 1870 int bytes; 1871 while ((bytes = read(fd, buf, sizeof(buf))) > 0) { 1872 st->print_raw(buf, bytes); 1873 } 1874 1875 close(fd); 1876 1877 return true; 1878 } 1879 1880 void os::print_dll_info(outputStream *st) { 1881 st->print_cr("Dynamic libraries:"); 1882 1883 char fname[32]; 1884 pid_t pid = os::Linux::gettid(); 1885 1886 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 1887 1888 if (!_print_ascii_file(fname, st)) { 1889 st->print("Can not get library information for pid = %d\n", pid); 1890 } 1891 } 1892 1893 1894 void os::print_os_info(outputStream* st) { 1895 st->print("OS:"); 1896 1897 // Try to identify popular distros. 1898 // Most Linux distributions have /etc/XXX-release file, which contains 1899 // the OS version string. Some have more than one /etc/XXX-release file 1900 // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.), 1901 // so the order is important. 1902 if (!_print_ascii_file("/etc/mandrake-release", st) && 1903 !_print_ascii_file("/etc/sun-release", st) && 1904 !_print_ascii_file("/etc/redhat-release", st) && 1905 !_print_ascii_file("/etc/SuSE-release", st) && 1906 !_print_ascii_file("/etc/turbolinux-release", st) && 1907 !_print_ascii_file("/etc/gentoo-release", st) && 1908 !_print_ascii_file("/etc/debian_version", st)) { 1909 st->print("Linux"); 1910 } 1911 st->cr(); 1912 1913 // kernel 1914 st->print("uname:"); 1915 struct utsname name; 1916 uname(&name); 1917 st->print(name.sysname); st->print(" "); 1918 st->print(name.release); st->print(" "); 1919 st->print(name.version); st->print(" "); 1920 st->print(name.machine); 1921 st->cr(); 1922 1923 // Print warning if unsafe chroot environment detected 1924 if (unsafe_chroot_detected) { 1925 st->print("WARNING!! "); 1926 st->print_cr(unstable_chroot_error); 1927 } 1928 1929 // libc, pthread 1930 st->print("libc:"); 1931 st->print(os::Linux::glibc_version()); st->print(" "); 1932 st->print(os::Linux::libpthread_version()); st->print(" "); 1933 if (os::Linux::is_LinuxThreads()) { 1934 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 1935 } 1936 st->cr(); 1937 1938 // rlimit 1939 st->print("rlimit:"); 1940 struct rlimit rlim; 1941 1942 st->print(" STACK "); 1943 getrlimit(RLIMIT_STACK, &rlim); 1944 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1945 else st->print("%uk", rlim.rlim_cur >> 10); 1946 1947 st->print(", CORE "); 1948 getrlimit(RLIMIT_CORE, &rlim); 1949 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1950 else st->print("%uk", rlim.rlim_cur >> 10); 1951 1952 st->print(", NPROC "); 1953 getrlimit(RLIMIT_NPROC, &rlim); 1954 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1955 else st->print("%d", rlim.rlim_cur); 1956 1957 st->print(", NOFILE "); 1958 getrlimit(RLIMIT_NOFILE, &rlim); 1959 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1960 else st->print("%d", rlim.rlim_cur); 1961 1962 st->print(", AS "); 1963 getrlimit(RLIMIT_AS, &rlim); 1964 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1965 else st->print("%uk", rlim.rlim_cur >> 10); 1966 st->cr(); 1967 1968 // load average 1969 st->print("load average:"); 1970 double loadavg[3]; 1971 os::loadavg(loadavg, 3); 1972 st->print("%0.02f %0.02f %0.02f", loadavg[0], loadavg[1], loadavg[2]); 1973 st->cr(); 1974 } 1975 1976 void os::print_memory_info(outputStream* st) { 1977 1978 st->print("Memory:"); 1979 st->print(" %dk page", os::vm_page_size()>>10); 1980 1981 // values in struct sysinfo are "unsigned long" 1982 struct sysinfo si; 1983 sysinfo(&si); 1984 1985 st->print(", physical " UINT64_FORMAT "k", 1986 os::physical_memory() >> 10); 1987 st->print("(" UINT64_FORMAT "k free)", 1988 os::available_memory() >> 10); 1989 st->print(", swap " UINT64_FORMAT "k", 1990 ((jlong)si.totalswap * si.mem_unit) >> 10); 1991 st->print("(" UINT64_FORMAT "k free)", 1992 ((jlong)si.freeswap * si.mem_unit) >> 10); 1993 st->cr(); 1994 } 1995 1996 // Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific 1997 // but they're the same for all the linux arch that we support 1998 // and they're the same for solaris but there's no common place to put this. 1999 const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR", 2000 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG", 2001 "ILL_COPROC", "ILL_BADSTK" }; 2002 2003 const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV", 2004 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES", 2005 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" }; 2006 2007 const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" }; 2008 2009 const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" }; 2010 2011 void os::print_siginfo(outputStream* st, void* siginfo) { 2012 st->print("siginfo:"); 2013 2014 const int buflen = 100; 2015 char buf[buflen]; 2016 siginfo_t *si = (siginfo_t*)siginfo; 2017 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen)); 2018 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) { 2019 st->print("si_errno=%s", buf); 2020 } else { 2021 st->print("si_errno=%d", si->si_errno); 2022 } 2023 const int c = si->si_code; 2024 assert(c > 0, "unexpected si_code"); 2025 switch (si->si_signo) { 2026 case SIGILL: 2027 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]); 2028 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2029 break; 2030 case SIGFPE: 2031 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]); 2032 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2033 break; 2034 case SIGSEGV: 2035 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]); 2036 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2037 break; 2038 case SIGBUS: 2039 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]); 2040 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2041 break; 2042 default: 2043 st->print(", si_code=%d", si->si_code); 2044 // no si_addr 2045 } 2046 2047 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2048 UseSharedSpaces) { 2049 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2050 if (mapinfo->is_in_shared_space(si->si_addr)) { 2051 st->print("\n\nError accessing class data sharing archive." \ 2052 " Mapped file inaccessible during execution, " \ 2053 " possible disk/network problem."); 2054 } 2055 } 2056 st->cr(); 2057 } 2058 2059 2060 static void print_signal_handler(outputStream* st, int sig, 2061 char* buf, size_t buflen); 2062 2063 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2064 st->print_cr("Signal Handlers:"); 2065 print_signal_handler(st, SIGSEGV, buf, buflen); 2066 print_signal_handler(st, SIGBUS , buf, buflen); 2067 print_signal_handler(st, SIGFPE , buf, buflen); 2068 print_signal_handler(st, SIGPIPE, buf, buflen); 2069 print_signal_handler(st, SIGXFSZ, buf, buflen); 2070 print_signal_handler(st, SIGILL , buf, buflen); 2071 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2072 print_signal_handler(st, SR_signum, buf, buflen); 2073 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2074 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2075 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2076 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2077 } 2078 2079 static char saved_jvm_path[MAXPATHLEN] = {0}; 2080 2081 // Find the full path to the current module, libjvm.so or libjvm_g.so 2082 void os::jvm_path(char *buf, jint len) { 2083 // Error checking. 2084 if (len < MAXPATHLEN) { 2085 assert(false, "must use a large-enough buffer"); 2086 buf[0] = '\0'; 2087 return; 2088 } 2089 // Lazy resolve the path to current module. 2090 if (saved_jvm_path[0] != 0) { 2091 strcpy(buf, saved_jvm_path); 2092 return; 2093 } 2094 2095 char dli_fname[MAXPATHLEN]; 2096 bool ret = dll_address_to_library_name( 2097 CAST_FROM_FN_PTR(address, os::jvm_path), 2098 dli_fname, sizeof(dli_fname), NULL); 2099 assert(ret != 0, "cannot locate libjvm"); 2100 if (realpath(dli_fname, buf) == NULL) 2101 return; 2102 2103 if (strcmp(Arguments::sun_java_launcher(), "gamma") == 0) { 2104 // Support for the gamma launcher. Typical value for buf is 2105 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at 2106 // the right place in the string, then assume we are installed in a JDK and 2107 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix 2108 // up the path so it looks like libjvm.so is installed there (append a 2109 // fake suffix hotspot/libjvm.so). 2110 const char *p = buf + strlen(buf) - 1; 2111 for (int count = 0; p > buf && count < 5; ++count) { 2112 for (--p; p > buf && *p != '/'; --p) 2113 /* empty */ ; 2114 } 2115 2116 if (strncmp(p, "/jre/lib/", 9) != 0) { 2117 // Look for JAVA_HOME in the environment. 2118 char* java_home_var = ::getenv("JAVA_HOME"); 2119 if (java_home_var != NULL && java_home_var[0] != 0) { 2120 // Check the current module name "libjvm.so" or "libjvm_g.so". 2121 p = strrchr(buf, '/'); 2122 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2123 p = strstr(p, "_g") ? "_g" : ""; 2124 2125 if (realpath(java_home_var, buf) == NULL) 2126 return; 2127 sprintf(buf + strlen(buf), "/jre/lib/%s", cpu_arch); 2128 if (0 == access(buf, F_OK)) { 2129 // Use current module name "libjvm[_g].so" instead of 2130 // "libjvm"debug_only("_g")".so" since for fastdebug version 2131 // we should have "libjvm.so" but debug_only("_g") adds "_g"! 2132 // It is used when we are choosing the HPI library's name 2133 // "libhpi[_g].so" in hpi::initialize_get_interface(). 2134 sprintf(buf + strlen(buf), "/hotspot/libjvm%s.so", p); 2135 } else { 2136 // Go back to path of .so 2137 if (realpath(dli_fname, buf) == NULL) 2138 return; 2139 } 2140 } 2141 } 2142 } 2143 2144 strcpy(saved_jvm_path, buf); 2145 } 2146 2147 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2148 // no prefix required, not even "_" 2149 } 2150 2151 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2152 // no suffix required 2153 } 2154 2155 //////////////////////////////////////////////////////////////////////////////// 2156 // sun.misc.Signal support 2157 2158 static volatile jint sigint_count = 0; 2159 2160 static void 2161 UserHandler(int sig, void *siginfo, void *context) { 2162 // 4511530 - sem_post is serialized and handled by the manager thread. When 2163 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2164 // don't want to flood the manager thread with sem_post requests. 2165 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2166 return; 2167 2168 // Ctrl-C is pressed during error reporting, likely because the error 2169 // handler fails to abort. Let VM die immediately. 2170 if (sig == SIGINT && is_error_reported()) { 2171 os::die(); 2172 } 2173 2174 os::signal_notify(sig); 2175 } 2176 2177 void* os::user_handler() { 2178 return CAST_FROM_FN_PTR(void*, UserHandler); 2179 } 2180 2181 extern "C" { 2182 typedef void (*sa_handler_t)(int); 2183 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2184 } 2185 2186 void* os::signal(int signal_number, void* handler) { 2187 struct sigaction sigAct, oldSigAct; 2188 2189 sigfillset(&(sigAct.sa_mask)); 2190 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2191 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2192 2193 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2194 // -1 means registration failed 2195 return (void *)-1; 2196 } 2197 2198 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2199 } 2200 2201 void os::signal_raise(int signal_number) { 2202 ::raise(signal_number); 2203 } 2204 2205 /* 2206 * The following code is moved from os.cpp for making this 2207 * code platform specific, which it is by its very nature. 2208 */ 2209 2210 // Will be modified when max signal is changed to be dynamic 2211 int os::sigexitnum_pd() { 2212 return NSIG; 2213 } 2214 2215 // a counter for each possible signal value 2216 static volatile jint pending_signals[NSIG+1] = { 0 }; 2217 2218 // Linux(POSIX) specific hand shaking semaphore. 2219 static sem_t sig_sem; 2220 2221 void os::signal_init_pd() { 2222 // Initialize signal structures 2223 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2224 2225 // Initialize signal semaphore 2226 ::sem_init(&sig_sem, 0, 0); 2227 } 2228 2229 void os::signal_notify(int sig) { 2230 Atomic::inc(&pending_signals[sig]); 2231 ::sem_post(&sig_sem); 2232 } 2233 2234 static int check_pending_signals(bool wait) { 2235 Atomic::store(0, &sigint_count); 2236 for (;;) { 2237 for (int i = 0; i < NSIG + 1; i++) { 2238 jint n = pending_signals[i]; 2239 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2240 return i; 2241 } 2242 } 2243 if (!wait) { 2244 return -1; 2245 } 2246 JavaThread *thread = JavaThread::current(); 2247 ThreadBlockInVM tbivm(thread); 2248 2249 bool threadIsSuspended; 2250 do { 2251 thread->set_suspend_equivalent(); 2252 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2253 ::sem_wait(&sig_sem); 2254 2255 // were we externally suspended while we were waiting? 2256 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2257 if (threadIsSuspended) { 2258 // 2259 // The semaphore has been incremented, but while we were waiting 2260 // another thread suspended us. We don't want to continue running 2261 // while suspended because that would surprise the thread that 2262 // suspended us. 2263 // 2264 ::sem_post(&sig_sem); 2265 2266 thread->java_suspend_self(); 2267 } 2268 } while (threadIsSuspended); 2269 } 2270 } 2271 2272 int os::signal_lookup() { 2273 return check_pending_signals(false); 2274 } 2275 2276 int os::signal_wait() { 2277 return check_pending_signals(true); 2278 } 2279 2280 //////////////////////////////////////////////////////////////////////////////// 2281 // Virtual Memory 2282 2283 int os::vm_page_size() { 2284 // Seems redundant as all get out 2285 assert(os::Linux::page_size() != -1, "must call os::init"); 2286 return os::Linux::page_size(); 2287 } 2288 2289 // Solaris allocates memory by pages. 2290 int os::vm_allocation_granularity() { 2291 assert(os::Linux::page_size() != -1, "must call os::init"); 2292 return os::Linux::page_size(); 2293 } 2294 2295 // Rationale behind this function: 2296 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2297 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2298 // samples for JITted code. Here we create private executable mapping over the code cache 2299 // and then we can use standard (well, almost, as mapping can change) way to provide 2300 // info for the reporting script by storing timestamp and location of symbol 2301 void linux_wrap_code(char* base, size_t size) { 2302 static volatile jint cnt = 0; 2303 2304 if (!UseOprofile) { 2305 return; 2306 } 2307 2308 char buf[PATH_MAX+1]; 2309 int num = Atomic::add(1, &cnt); 2310 2311 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d", 2312 os::get_temp_directory(), os::current_process_id(), num); 2313 unlink(buf); 2314 2315 int fd = open(buf, O_CREAT | O_RDWR, S_IRWXU); 2316 2317 if (fd != -1) { 2318 off_t rv = lseek(fd, size-2, SEEK_SET); 2319 if (rv != (off_t)-1) { 2320 if (write(fd, "", 1) == 1) { 2321 mmap(base, size, 2322 PROT_READ|PROT_WRITE|PROT_EXEC, 2323 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2324 } 2325 } 2326 close(fd); 2327 unlink(buf); 2328 } 2329 } 2330 2331 // NOTE: Linux kernel does not really reserve the pages for us. 2332 // All it does is to check if there are enough free pages 2333 // left at the time of mmap(). This could be a potential 2334 // problem. 2335 bool os::commit_memory(char* addr, size_t size, bool exec) { 2336 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2337 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2338 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2339 return res != (uintptr_t) MAP_FAILED; 2340 } 2341 2342 bool os::commit_memory(char* addr, size_t size, size_t alignment_hint, 2343 bool exec) { 2344 return commit_memory(addr, size, exec); 2345 } 2346 2347 void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) { } 2348 2349 void os::free_memory(char *addr, size_t bytes) { 2350 ::mmap(addr, bytes, PROT_READ | PROT_WRITE, 2351 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2352 } 2353 2354 void os::numa_make_global(char *addr, size_t bytes) { 2355 Linux::numa_interleave_memory(addr, bytes); 2356 } 2357 2358 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2359 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2360 } 2361 2362 bool os::numa_topology_changed() { return false; } 2363 2364 size_t os::numa_get_groups_num() { 2365 int max_node = Linux::numa_max_node(); 2366 return max_node > 0 ? max_node + 1 : 1; 2367 } 2368 2369 int os::numa_get_group_id() { 2370 int cpu_id = Linux::sched_getcpu(); 2371 if (cpu_id != -1) { 2372 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2373 if (lgrp_id != -1) { 2374 return lgrp_id; 2375 } 2376 } 2377 return 0; 2378 } 2379 2380 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2381 for (size_t i = 0; i < size; i++) { 2382 ids[i] = i; 2383 } 2384 return size; 2385 } 2386 2387 bool os::get_page_info(char *start, page_info* info) { 2388 return false; 2389 } 2390 2391 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2392 return end; 2393 } 2394 2395 extern "C" void numa_warn(int number, char *where, ...) { } 2396 extern "C" void numa_error(char *where) { } 2397 2398 2399 // If we are running with libnuma version > 2, then we should 2400 // be trying to use symbols with versions 1.1 2401 // If we are running with earlier version, which did not have symbol versions, 2402 // we should use the base version. 2403 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2404 void *f = dlvsym(handle, name, "libnuma_1.1"); 2405 if (f == NULL) { 2406 f = dlsym(handle, name); 2407 } 2408 return f; 2409 } 2410 2411 bool os::Linux::libnuma_init() { 2412 // sched_getcpu() should be in libc. 2413 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2414 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2415 2416 if (sched_getcpu() != -1) { // Does it work? 2417 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2418 if (handle != NULL) { 2419 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2420 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2421 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2422 libnuma_dlsym(handle, "numa_max_node"))); 2423 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2424 libnuma_dlsym(handle, "numa_available"))); 2425 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2426 libnuma_dlsym(handle, "numa_tonode_memory"))); 2427 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2428 libnuma_dlsym(handle, "numa_interleave_memory"))); 2429 2430 2431 if (numa_available() != -1) { 2432 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2433 // Create a cpu -> node mapping 2434 _cpu_to_node = new (ResourceObj::C_HEAP) GrowableArray<int>(0, true); 2435 rebuild_cpu_to_node_map(); 2436 return true; 2437 } 2438 } 2439 } 2440 return false; 2441 } 2442 2443 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2444 // The table is later used in get_node_by_cpu(). 2445 void os::Linux::rebuild_cpu_to_node_map() { 2446 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2447 // in libnuma (possible values are starting from 16, 2448 // and continuing up with every other power of 2, but less 2449 // than the maximum number of CPUs supported by kernel), and 2450 // is a subject to change (in libnuma version 2 the requirements 2451 // are more reasonable) we'll just hardcode the number they use 2452 // in the library. 2453 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2454 2455 size_t cpu_num = os::active_processor_count(); 2456 size_t cpu_map_size = NCPUS / BitsPerCLong; 2457 size_t cpu_map_valid_size = 2458 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2459 2460 cpu_to_node()->clear(); 2461 cpu_to_node()->at_grow(cpu_num - 1); 2462 size_t node_num = numa_get_groups_num(); 2463 2464 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size); 2465 for (size_t i = 0; i < node_num; i++) { 2466 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2467 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2468 if (cpu_map[j] != 0) { 2469 for (size_t k = 0; k < BitsPerCLong; k++) { 2470 if (cpu_map[j] & (1UL << k)) { 2471 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2472 } 2473 } 2474 } 2475 } 2476 } 2477 } 2478 FREE_C_HEAP_ARRAY(unsigned long, cpu_map); 2479 } 2480 2481 int os::Linux::get_node_by_cpu(int cpu_id) { 2482 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2483 return cpu_to_node()->at(cpu_id); 2484 } 2485 return -1; 2486 } 2487 2488 GrowableArray<int>* os::Linux::_cpu_to_node; 2489 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2490 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2491 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2492 os::Linux::numa_available_func_t os::Linux::_numa_available; 2493 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2494 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2495 unsigned long* os::Linux::_numa_all_nodes; 2496 2497 bool os::uncommit_memory(char* addr, size_t size) { 2498 return ::mmap(addr, size, PROT_NONE, 2499 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0) 2500 != MAP_FAILED; 2501 } 2502 2503 // Linux uses a growable mapping for the stack, and if the mapping for 2504 // the stack guard pages is not removed when we detach a thread the 2505 // stack cannot grow beyond the pages where the stack guard was 2506 // mapped. If at some point later in the process the stack expands to 2507 // that point, the Linux kernel cannot expand the stack any further 2508 // because the guard pages are in the way, and a segfault occurs. 2509 // 2510 // However, it's essential not to split the stack region by unmapping 2511 // a region (leaving a hole) that's already part of the stack mapping, 2512 // so if the stack mapping has already grown beyond the guard pages at 2513 // the time we create them, we have to truncate the stack mapping. 2514 // So, we need to know the extent of the stack mapping when 2515 // create_stack_guard_pages() is called. 2516 2517 // Find the bounds of the stack mapping. Return true for success. 2518 // 2519 // We only need this for stacks that are growable: at the time of 2520 // writing thread stacks don't use growable mappings (i.e. those 2521 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 2522 // only applies to the main thread. 2523 static bool 2524 get_stack_bounds(uintptr_t *bottom, uintptr_t *top) 2525 { 2526 FILE *f = fopen("/proc/self/maps", "r"); 2527 if (f == NULL) 2528 return false; 2529 2530 while (!feof(f)) { 2531 size_t dummy; 2532 char *str = NULL; 2533 ssize_t len = getline(&str, &dummy, f); 2534 if (len == -1) { 2535 fclose(f); 2536 return false; 2537 } 2538 2539 if (len > 0 && str[len-1] == '\n') { 2540 str[len-1] = 0; 2541 len--; 2542 } 2543 2544 static const char *stack_str = "[stack]"; 2545 if (len > (ssize_t)strlen(stack_str) 2546 && (strcmp(str + len - strlen(stack_str), stack_str) == 0)) { 2547 if (sscanf(str, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) { 2548 uintptr_t sp = (uintptr_t)__builtin_frame_address(0); 2549 if (sp >= *bottom && sp <= *top) { 2550 free(str); 2551 fclose(f); 2552 return true; 2553 } 2554 } 2555 } 2556 free(str); 2557 } 2558 fclose(f); 2559 return false; 2560 } 2561 2562 // If the (growable) stack mapping already extends beyond the point 2563 // where we're going to put our guard pages, truncate the mapping at 2564 // that point by munmap()ping it. This ensures that when we later 2565 // munmap() the guard pages we don't leave a hole in the stack 2566 // mapping. 2567 bool os::create_stack_guard_pages(char* addr, size_t size) { 2568 uintptr_t stack_extent, stack_base; 2569 if (get_stack_bounds(&stack_extent, &stack_base)) { 2570 if (stack_extent < (uintptr_t)addr) 2571 ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent); 2572 } 2573 2574 return os::commit_memory(addr, size); 2575 } 2576 2577 // If this is a growable mapping, remove the guard pages entirely by 2578 // munmap()ping them. If not, just call uncommit_memory(). 2579 bool os::remove_stack_guard_pages(char* addr, size_t size) { 2580 uintptr_t stack_extent, stack_base; 2581 if (get_stack_bounds(&stack_extent, &stack_base)) { 2582 return ::munmap(addr, size) == 0; 2583 } 2584 2585 return os::uncommit_memory(addr, size); 2586 } 2587 2588 static address _highest_vm_reserved_address = NULL; 2589 2590 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 2591 // at 'requested_addr'. If there are existing memory mappings at the same 2592 // location, however, they will be overwritten. If 'fixed' is false, 2593 // 'requested_addr' is only treated as a hint, the return value may or 2594 // may not start from the requested address. Unlike Linux mmap(), this 2595 // function returns NULL to indicate failure. 2596 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 2597 char * addr; 2598 int flags; 2599 2600 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 2601 if (fixed) { 2602 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 2603 flags |= MAP_FIXED; 2604 } 2605 2606 // Map uncommitted pages PROT_READ and PROT_WRITE, change access 2607 // to PROT_EXEC if executable when we commit the page. 2608 addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE, 2609 flags, -1, 0); 2610 2611 if (addr != MAP_FAILED) { 2612 // anon_mmap() should only get called during VM initialization, 2613 // don't need lock (actually we can skip locking even it can be called 2614 // from multiple threads, because _highest_vm_reserved_address is just a 2615 // hint about the upper limit of non-stack memory regions.) 2616 if ((address)addr + bytes > _highest_vm_reserved_address) { 2617 _highest_vm_reserved_address = (address)addr + bytes; 2618 } 2619 } 2620 2621 return addr == MAP_FAILED ? NULL : addr; 2622 } 2623 2624 // Don't update _highest_vm_reserved_address, because there might be memory 2625 // regions above addr + size. If so, releasing a memory region only creates 2626 // a hole in the address space, it doesn't help prevent heap-stack collision. 2627 // 2628 static int anon_munmap(char * addr, size_t size) { 2629 return ::munmap(addr, size) == 0; 2630 } 2631 2632 char* os::reserve_memory(size_t bytes, char* requested_addr, 2633 size_t alignment_hint) { 2634 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 2635 } 2636 2637 bool os::release_memory(char* addr, size_t size) { 2638 return anon_munmap(addr, size); 2639 } 2640 2641 static address highest_vm_reserved_address() { 2642 return _highest_vm_reserved_address; 2643 } 2644 2645 static bool linux_mprotect(char* addr, size_t size, int prot) { 2646 // Linux wants the mprotect address argument to be page aligned. 2647 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 2648 2649 // According to SUSv3, mprotect() should only be used with mappings 2650 // established by mmap(), and mmap() always maps whole pages. Unaligned 2651 // 'addr' likely indicates problem in the VM (e.g. trying to change 2652 // protection of malloc'ed or statically allocated memory). Check the 2653 // caller if you hit this assert. 2654 assert(addr == bottom, "sanity check"); 2655 2656 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 2657 return ::mprotect(bottom, size, prot) == 0; 2658 } 2659 2660 // Set protections specified 2661 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 2662 bool is_committed) { 2663 unsigned int p = 0; 2664 switch (prot) { 2665 case MEM_PROT_NONE: p = PROT_NONE; break; 2666 case MEM_PROT_READ: p = PROT_READ; break; 2667 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 2668 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 2669 default: 2670 ShouldNotReachHere(); 2671 } 2672 // is_committed is unused. 2673 return linux_mprotect(addr, bytes, p); 2674 } 2675 2676 bool os::guard_memory(char* addr, size_t size) { 2677 return linux_mprotect(addr, size, PROT_NONE); 2678 } 2679 2680 bool os::unguard_memory(char* addr, size_t size) { 2681 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 2682 } 2683 2684 // Large page support 2685 2686 static size_t _large_page_size = 0; 2687 2688 bool os::large_page_init() { 2689 if (!UseLargePages) return false; 2690 2691 if (LargePageSizeInBytes) { 2692 _large_page_size = LargePageSizeInBytes; 2693 } else { 2694 // large_page_size on Linux is used to round up heap size. x86 uses either 2695 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 2696 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 2697 // page as large as 256M. 2698 // 2699 // Here we try to figure out page size by parsing /proc/meminfo and looking 2700 // for a line with the following format: 2701 // Hugepagesize: 2048 kB 2702 // 2703 // If we can't determine the value (e.g. /proc is not mounted, or the text 2704 // format has been changed), we'll use the largest page size supported by 2705 // the processor. 2706 2707 #ifndef ZERO 2708 _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M); 2709 #endif // ZERO 2710 2711 FILE *fp = fopen("/proc/meminfo", "r"); 2712 if (fp) { 2713 while (!feof(fp)) { 2714 int x = 0; 2715 char buf[16]; 2716 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 2717 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 2718 _large_page_size = x * K; 2719 break; 2720 } 2721 } else { 2722 // skip to next line 2723 for (;;) { 2724 int ch = fgetc(fp); 2725 if (ch == EOF || ch == (int)'\n') break; 2726 } 2727 } 2728 } 2729 fclose(fp); 2730 } 2731 } 2732 2733 const size_t default_page_size = (size_t)Linux::page_size(); 2734 if (_large_page_size > default_page_size) { 2735 _page_sizes[0] = _large_page_size; 2736 _page_sizes[1] = default_page_size; 2737 _page_sizes[2] = 0; 2738 } 2739 2740 // Large page support is available on 2.6 or newer kernel, some vendors 2741 // (e.g. Redhat) have backported it to their 2.4 based distributions. 2742 // We optimistically assume the support is available. If later it turns out 2743 // not true, VM will automatically switch to use regular page size. 2744 return true; 2745 } 2746 2747 #ifndef SHM_HUGETLB 2748 #define SHM_HUGETLB 04000 2749 #endif 2750 2751 char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) { 2752 // "exec" is passed in but not used. Creating the shared image for 2753 // the code cache doesn't have an SHM_X executable permission to check. 2754 assert(UseLargePages, "only for large pages"); 2755 2756 key_t key = IPC_PRIVATE; 2757 char *addr; 2758 2759 bool warn_on_failure = UseLargePages && 2760 (!FLAG_IS_DEFAULT(UseLargePages) || 2761 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 2762 ); 2763 char msg[128]; 2764 2765 // Create a large shared memory region to attach to based on size. 2766 // Currently, size is the total size of the heap 2767 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 2768 if (shmid == -1) { 2769 // Possible reasons for shmget failure: 2770 // 1. shmmax is too small for Java heap. 2771 // > check shmmax value: cat /proc/sys/kernel/shmmax 2772 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 2773 // 2. not enough large page memory. 2774 // > check available large pages: cat /proc/meminfo 2775 // > increase amount of large pages: 2776 // echo new_value > /proc/sys/vm/nr_hugepages 2777 // Note 1: different Linux may use different name for this property, 2778 // e.g. on Redhat AS-3 it is "hugetlb_pool". 2779 // Note 2: it's possible there's enough physical memory available but 2780 // they are so fragmented after a long run that they can't 2781 // coalesce into large pages. Try to reserve large pages when 2782 // the system is still "fresh". 2783 if (warn_on_failure) { 2784 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 2785 warning(msg); 2786 } 2787 return NULL; 2788 } 2789 2790 // attach to the region 2791 addr = (char*)shmat(shmid, req_addr, 0); 2792 int err = errno; 2793 2794 // Remove shmid. If shmat() is successful, the actual shared memory segment 2795 // will be deleted when it's detached by shmdt() or when the process 2796 // terminates. If shmat() is not successful this will remove the shared 2797 // segment immediately. 2798 shmctl(shmid, IPC_RMID, NULL); 2799 2800 if ((intptr_t)addr == -1) { 2801 if (warn_on_failure) { 2802 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 2803 warning(msg); 2804 } 2805 return NULL; 2806 } 2807 2808 return addr; 2809 } 2810 2811 bool os::release_memory_special(char* base, size_t bytes) { 2812 // detaching the SHM segment will also delete it, see reserve_memory_special() 2813 int rslt = shmdt(base); 2814 return rslt == 0; 2815 } 2816 2817 size_t os::large_page_size() { 2818 return _large_page_size; 2819 } 2820 2821 // Linux does not support anonymous mmap with large page memory. The only way 2822 // to reserve large page memory without file backing is through SysV shared 2823 // memory API. The entire memory region is committed and pinned upfront. 2824 // Hopefully this will change in the future... 2825 bool os::can_commit_large_page_memory() { 2826 return false; 2827 } 2828 2829 bool os::can_execute_large_page_memory() { 2830 return false; 2831 } 2832 2833 // Reserve memory at an arbitrary address, only if that area is 2834 // available (and not reserved for something else). 2835 2836 char* os::attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 2837 const int max_tries = 10; 2838 char* base[max_tries]; 2839 size_t size[max_tries]; 2840 const size_t gap = 0x000000; 2841 2842 // Assert only that the size is a multiple of the page size, since 2843 // that's all that mmap requires, and since that's all we really know 2844 // about at this low abstraction level. If we need higher alignment, 2845 // we can either pass an alignment to this method or verify alignment 2846 // in one of the methods further up the call chain. See bug 5044738. 2847 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 2848 2849 // Repeatedly allocate blocks until the block is allocated at the 2850 // right spot. Give up after max_tries. Note that reserve_memory() will 2851 // automatically update _highest_vm_reserved_address if the call is 2852 // successful. The variable tracks the highest memory address every reserved 2853 // by JVM. It is used to detect heap-stack collision if running with 2854 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 2855 // space than needed, it could confuse the collision detecting code. To 2856 // solve the problem, save current _highest_vm_reserved_address and 2857 // calculate the correct value before return. 2858 address old_highest = _highest_vm_reserved_address; 2859 2860 // Linux mmap allows caller to pass an address as hint; give it a try first, 2861 // if kernel honors the hint then we can return immediately. 2862 char * addr = anon_mmap(requested_addr, bytes, false); 2863 if (addr == requested_addr) { 2864 return requested_addr; 2865 } 2866 2867 if (addr != NULL) { 2868 // mmap() is successful but it fails to reserve at the requested address 2869 anon_munmap(addr, bytes); 2870 } 2871 2872 int i; 2873 for (i = 0; i < max_tries; ++i) { 2874 base[i] = reserve_memory(bytes); 2875 2876 if (base[i] != NULL) { 2877 // Is this the block we wanted? 2878 if (base[i] == requested_addr) { 2879 size[i] = bytes; 2880 break; 2881 } 2882 2883 // Does this overlap the block we wanted? Give back the overlapped 2884 // parts and try again. 2885 2886 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 2887 if (top_overlap >= 0 && top_overlap < bytes) { 2888 unmap_memory(base[i], top_overlap); 2889 base[i] += top_overlap; 2890 size[i] = bytes - top_overlap; 2891 } else { 2892 size_t bottom_overlap = base[i] + bytes - requested_addr; 2893 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 2894 unmap_memory(requested_addr, bottom_overlap); 2895 size[i] = bytes - bottom_overlap; 2896 } else { 2897 size[i] = bytes; 2898 } 2899 } 2900 } 2901 } 2902 2903 // Give back the unused reserved pieces. 2904 2905 for (int j = 0; j < i; ++j) { 2906 if (base[j] != NULL) { 2907 unmap_memory(base[j], size[j]); 2908 } 2909 } 2910 2911 if (i < max_tries) { 2912 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 2913 return requested_addr; 2914 } else { 2915 _highest_vm_reserved_address = old_highest; 2916 return NULL; 2917 } 2918 } 2919 2920 size_t os::read(int fd, void *buf, unsigned int nBytes) { 2921 return ::read(fd, buf, nBytes); 2922 } 2923 2924 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation. 2925 // Solaris uses poll(), linux uses park(). 2926 // Poll() is likely a better choice, assuming that Thread.interrupt() 2927 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with 2928 // SIGSEGV, see 4355769. 2929 2930 const int NANOSECS_PER_MILLISECS = 1000000; 2931 2932 int os::sleep(Thread* thread, jlong millis, bool interruptible) { 2933 assert(thread == Thread::current(), "thread consistency check"); 2934 2935 ParkEvent * const slp = thread->_SleepEvent ; 2936 slp->reset() ; 2937 OrderAccess::fence() ; 2938 2939 if (interruptible) { 2940 jlong prevtime = javaTimeNanos(); 2941 2942 for (;;) { 2943 if (os::is_interrupted(thread, true)) { 2944 return OS_INTRPT; 2945 } 2946 2947 jlong newtime = javaTimeNanos(); 2948 2949 if (newtime - prevtime < 0) { 2950 // time moving backwards, should only happen if no monotonic clock 2951 // not a guarantee() because JVM should not abort on kernel/glibc bugs 2952 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 2953 } else { 2954 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS; 2955 } 2956 2957 if(millis <= 0) { 2958 return OS_OK; 2959 } 2960 2961 prevtime = newtime; 2962 2963 { 2964 assert(thread->is_Java_thread(), "sanity check"); 2965 JavaThread *jt = (JavaThread *) thread; 2966 ThreadBlockInVM tbivm(jt); 2967 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */); 2968 2969 jt->set_suspend_equivalent(); 2970 // cleared by handle_special_suspend_equivalent_condition() or 2971 // java_suspend_self() via check_and_wait_while_suspended() 2972 2973 slp->park(millis); 2974 2975 // were we externally suspended while we were waiting? 2976 jt->check_and_wait_while_suspended(); 2977 } 2978 } 2979 } else { 2980 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 2981 jlong prevtime = javaTimeNanos(); 2982 2983 for (;;) { 2984 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on 2985 // the 1st iteration ... 2986 jlong newtime = javaTimeNanos(); 2987 2988 if (newtime - prevtime < 0) { 2989 // time moving backwards, should only happen if no monotonic clock 2990 // not a guarantee() because JVM should not abort on kernel/glibc bugs 2991 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 2992 } else { 2993 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS; 2994 } 2995 2996 if(millis <= 0) break ; 2997 2998 prevtime = newtime; 2999 slp->park(millis); 3000 } 3001 return OS_OK ; 3002 } 3003 } 3004 3005 int os::naked_sleep() { 3006 // %% make the sleep time an integer flag. for now use 1 millisec. 3007 return os::sleep(Thread::current(), 1, false); 3008 } 3009 3010 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 3011 void os::infinite_sleep() { 3012 while (true) { // sleep forever ... 3013 ::sleep(100); // ... 100 seconds at a time 3014 } 3015 } 3016 3017 // Used to convert frequent JVM_Yield() to nops 3018 bool os::dont_yield() { 3019 return DontYieldALot; 3020 } 3021 3022 void os::yield() { 3023 sched_yield(); 3024 } 3025 3026 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 3027 3028 void os::yield_all(int attempts) { 3029 // Yields to all threads, including threads with lower priorities 3030 // Threads on Linux are all with same priority. The Solaris style 3031 // os::yield_all() with nanosleep(1ms) is not necessary. 3032 sched_yield(); 3033 } 3034 3035 // Called from the tight loops to possibly influence time-sharing heuristics 3036 void os::loop_breaker(int attempts) { 3037 os::yield_all(attempts); 3038 } 3039 3040 //////////////////////////////////////////////////////////////////////////////// 3041 // thread priority support 3042 3043 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 3044 // only supports dynamic priority, static priority must be zero. For real-time 3045 // applications, Linux supports SCHED_RR which allows static priority (1-99). 3046 // However, for large multi-threaded applications, SCHED_RR is not only slower 3047 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 3048 // of 5 runs - Sep 2005). 3049 // 3050 // The following code actually changes the niceness of kernel-thread/LWP. It 3051 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 3052 // not the entire user process, and user level threads are 1:1 mapped to kernel 3053 // threads. It has always been the case, but could change in the future. For 3054 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 3055 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 3056 3057 int os::java_to_os_priority[MaxPriority + 1] = { 3058 19, // 0 Entry should never be used 3059 3060 4, // 1 MinPriority 3061 3, // 2 3062 2, // 3 3063 3064 1, // 4 3065 0, // 5 NormPriority 3066 -1, // 6 3067 3068 -2, // 7 3069 -3, // 8 3070 -4, // 9 NearMaxPriority 3071 3072 -5 // 10 MaxPriority 3073 }; 3074 3075 static int prio_init() { 3076 if (ThreadPriorityPolicy == 1) { 3077 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 3078 // if effective uid is not root. Perhaps, a more elegant way of doing 3079 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 3080 if (geteuid() != 0) { 3081 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 3082 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 3083 } 3084 ThreadPriorityPolicy = 0; 3085 } 3086 } 3087 return 0; 3088 } 3089 3090 OSReturn os::set_native_priority(Thread* thread, int newpri) { 3091 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 3092 3093 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3094 return (ret == 0) ? OS_OK : OS_ERR; 3095 } 3096 3097 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3098 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3099 *priority_ptr = java_to_os_priority[NormPriority]; 3100 return OS_OK; 3101 } 3102 3103 errno = 0; 3104 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3105 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3106 } 3107 3108 // Hint to the underlying OS that a task switch would not be good. 3109 // Void return because it's a hint and can fail. 3110 void os::hint_no_preempt() {} 3111 3112 //////////////////////////////////////////////////////////////////////////////// 3113 // suspend/resume support 3114 3115 // the low-level signal-based suspend/resume support is a remnant from the 3116 // old VM-suspension that used to be for java-suspension, safepoints etc, 3117 // within hotspot. Now there is a single use-case for this: 3118 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3119 // that runs in the watcher thread. 3120 // The remaining code is greatly simplified from the more general suspension 3121 // code that used to be used. 3122 // 3123 // The protocol is quite simple: 3124 // - suspend: 3125 // - sends a signal to the target thread 3126 // - polls the suspend state of the osthread using a yield loop 3127 // - target thread signal handler (SR_handler) sets suspend state 3128 // and blocks in sigsuspend until continued 3129 // - resume: 3130 // - sets target osthread state to continue 3131 // - sends signal to end the sigsuspend loop in the SR_handler 3132 // 3133 // Note that the SR_lock plays no role in this suspend/resume protocol. 3134 // 3135 3136 static void resume_clear_context(OSThread *osthread) { 3137 osthread->set_ucontext(NULL); 3138 osthread->set_siginfo(NULL); 3139 3140 // notify the suspend action is completed, we have now resumed 3141 osthread->sr.clear_suspended(); 3142 } 3143 3144 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 3145 osthread->set_ucontext(context); 3146 osthread->set_siginfo(siginfo); 3147 } 3148 3149 // 3150 // Handler function invoked when a thread's execution is suspended or 3151 // resumed. We have to be careful that only async-safe functions are 3152 // called here (Note: most pthread functions are not async safe and 3153 // should be avoided.) 3154 // 3155 // Note: sigwait() is a more natural fit than sigsuspend() from an 3156 // interface point of view, but sigwait() prevents the signal hander 3157 // from being run. libpthread would get very confused by not having 3158 // its signal handlers run and prevents sigwait()'s use with the 3159 // mutex granting granting signal. 3160 // 3161 // Currently only ever called on the VMThread 3162 // 3163 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3164 // Save and restore errno to avoid confusing native code with EINTR 3165 // after sigsuspend. 3166 int old_errno = errno; 3167 3168 Thread* thread = Thread::current(); 3169 OSThread* osthread = thread->osthread(); 3170 assert(thread->is_VM_thread(), "Must be VMThread"); 3171 // read current suspend action 3172 int action = osthread->sr.suspend_action(); 3173 if (action == SR_SUSPEND) { 3174 suspend_save_context(osthread, siginfo, context); 3175 3176 // Notify the suspend action is about to be completed. do_suspend() 3177 // waits until SR_SUSPENDED is set and then returns. We will wait 3178 // here for a resume signal and that completes the suspend-other 3179 // action. do_suspend/do_resume is always called as a pair from 3180 // the same thread - so there are no races 3181 3182 // notify the caller 3183 osthread->sr.set_suspended(); 3184 3185 sigset_t suspend_set; // signals for sigsuspend() 3186 3187 // get current set of blocked signals and unblock resume signal 3188 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3189 sigdelset(&suspend_set, SR_signum); 3190 3191 // wait here until we are resumed 3192 do { 3193 sigsuspend(&suspend_set); 3194 // ignore all returns until we get a resume signal 3195 } while (osthread->sr.suspend_action() != SR_CONTINUE); 3196 3197 resume_clear_context(osthread); 3198 3199 } else { 3200 assert(action == SR_CONTINUE, "unexpected sr action"); 3201 // nothing special to do - just leave the handler 3202 } 3203 3204 errno = old_errno; 3205 } 3206 3207 3208 static int SR_initialize() { 3209 struct sigaction act; 3210 char *s; 3211 /* Get signal number to use for suspend/resume */ 3212 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 3213 int sig = ::strtol(s, 0, 10); 3214 if (sig > 0 || sig < _NSIG) { 3215 SR_signum = sig; 3216 } 3217 } 3218 3219 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 3220 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 3221 3222 sigemptyset(&SR_sigset); 3223 sigaddset(&SR_sigset, SR_signum); 3224 3225 /* Set up signal handler for suspend/resume */ 3226 act.sa_flags = SA_RESTART|SA_SIGINFO; 3227 act.sa_handler = (void (*)(int)) SR_handler; 3228 3229 // SR_signum is blocked by default. 3230 // 4528190 - We also need to block pthread restart signal (32 on all 3231 // supported Linux platforms). Note that LinuxThreads need to block 3232 // this signal for all threads to work properly. So we don't have 3233 // to use hard-coded signal number when setting up the mask. 3234 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 3235 3236 if (sigaction(SR_signum, &act, 0) == -1) { 3237 return -1; 3238 } 3239 3240 // Save signal flag 3241 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 3242 return 0; 3243 } 3244 3245 static int SR_finalize() { 3246 return 0; 3247 } 3248 3249 3250 // returns true on success and false on error - really an error is fatal 3251 // but this seems the normal response to library errors 3252 static bool do_suspend(OSThread* osthread) { 3253 // mark as suspended and send signal 3254 osthread->sr.set_suspend_action(SR_SUSPEND); 3255 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3256 assert_status(status == 0, status, "pthread_kill"); 3257 3258 // check status and wait until notified of suspension 3259 if (status == 0) { 3260 for (int i = 0; !osthread->sr.is_suspended(); i++) { 3261 os::yield_all(i); 3262 } 3263 osthread->sr.set_suspend_action(SR_NONE); 3264 return true; 3265 } 3266 else { 3267 osthread->sr.set_suspend_action(SR_NONE); 3268 return false; 3269 } 3270 } 3271 3272 static void do_resume(OSThread* osthread) { 3273 assert(osthread->sr.is_suspended(), "thread should be suspended"); 3274 osthread->sr.set_suspend_action(SR_CONTINUE); 3275 3276 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3277 assert_status(status == 0, status, "pthread_kill"); 3278 // check status and wait unit notified of resumption 3279 if (status == 0) { 3280 for (int i = 0; osthread->sr.is_suspended(); i++) { 3281 os::yield_all(i); 3282 } 3283 } 3284 osthread->sr.set_suspend_action(SR_NONE); 3285 } 3286 3287 //////////////////////////////////////////////////////////////////////////////// 3288 // interrupt support 3289 3290 void os::interrupt(Thread* thread) { 3291 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3292 "possibility of dangling Thread pointer"); 3293 3294 OSThread* osthread = thread->osthread(); 3295 3296 if (!osthread->interrupted()) { 3297 osthread->set_interrupted(true); 3298 // More than one thread can get here with the same value of osthread, 3299 // resulting in multiple notifications. We do, however, want the store 3300 // to interrupted() to be visible to other threads before we execute unpark(). 3301 OrderAccess::fence(); 3302 ParkEvent * const slp = thread->_SleepEvent ; 3303 if (slp != NULL) slp->unpark() ; 3304 } 3305 3306 // For JSR166. Unpark even if interrupt status already was set 3307 if (thread->is_Java_thread()) 3308 ((JavaThread*)thread)->parker()->unpark(); 3309 3310 ParkEvent * ev = thread->_ParkEvent ; 3311 if (ev != NULL) ev->unpark() ; 3312 3313 } 3314 3315 bool os::is_interrupted(Thread* thread, bool clear_interrupted) { 3316 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3317 "possibility of dangling Thread pointer"); 3318 3319 OSThread* osthread = thread->osthread(); 3320 3321 bool interrupted = osthread->interrupted(); 3322 3323 if (interrupted && clear_interrupted) { 3324 osthread->set_interrupted(false); 3325 // consider thread->_SleepEvent->reset() ... optional optimization 3326 } 3327 3328 return interrupted; 3329 } 3330 3331 /////////////////////////////////////////////////////////////////////////////////// 3332 // signal handling (except suspend/resume) 3333 3334 // This routine may be used by user applications as a "hook" to catch signals. 3335 // The user-defined signal handler must pass unrecognized signals to this 3336 // routine, and if it returns true (non-zero), then the signal handler must 3337 // return immediately. If the flag "abort_if_unrecognized" is true, then this 3338 // routine will never retun false (zero), but instead will execute a VM panic 3339 // routine kill the process. 3340 // 3341 // If this routine returns false, it is OK to call it again. This allows 3342 // the user-defined signal handler to perform checks either before or after 3343 // the VM performs its own checks. Naturally, the user code would be making 3344 // a serious error if it tried to handle an exception (such as a null check 3345 // or breakpoint) that the VM was generating for its own correct operation. 3346 // 3347 // This routine may recognize any of the following kinds of signals: 3348 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 3349 // It should be consulted by handlers for any of those signals. 3350 // 3351 // The caller of this routine must pass in the three arguments supplied 3352 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 3353 // field of the structure passed to sigaction(). This routine assumes that 3354 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 3355 // 3356 // Note that the VM will print warnings if it detects conflicting signal 3357 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 3358 // 3359 extern "C" int 3360 JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 3361 void* ucontext, int abort_if_unrecognized); 3362 3363 void signalHandler(int sig, siginfo_t* info, void* uc) { 3364 assert(info != NULL && uc != NULL, "it must be old kernel"); 3365 JVM_handle_linux_signal(sig, info, uc, true); 3366 } 3367 3368 3369 // This boolean allows users to forward their own non-matching signals 3370 // to JVM_handle_linux_signal, harmlessly. 3371 bool os::Linux::signal_handlers_are_installed = false; 3372 3373 // For signal-chaining 3374 struct sigaction os::Linux::sigact[MAXSIGNUM]; 3375 unsigned int os::Linux::sigs = 0; 3376 bool os::Linux::libjsig_is_loaded = false; 3377 typedef struct sigaction *(*get_signal_t)(int); 3378 get_signal_t os::Linux::get_signal_action = NULL; 3379 3380 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 3381 struct sigaction *actp = NULL; 3382 3383 if (libjsig_is_loaded) { 3384 // Retrieve the old signal handler from libjsig 3385 actp = (*get_signal_action)(sig); 3386 } 3387 if (actp == NULL) { 3388 // Retrieve the preinstalled signal handler from jvm 3389 actp = get_preinstalled_handler(sig); 3390 } 3391 3392 return actp; 3393 } 3394 3395 static bool call_chained_handler(struct sigaction *actp, int sig, 3396 siginfo_t *siginfo, void *context) { 3397 // Call the old signal handler 3398 if (actp->sa_handler == SIG_DFL) { 3399 // It's more reasonable to let jvm treat it as an unexpected exception 3400 // instead of taking the default action. 3401 return false; 3402 } else if (actp->sa_handler != SIG_IGN) { 3403 if ((actp->sa_flags & SA_NODEFER) == 0) { 3404 // automaticlly block the signal 3405 sigaddset(&(actp->sa_mask), sig); 3406 } 3407 3408 sa_handler_t hand; 3409 sa_sigaction_t sa; 3410 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 3411 // retrieve the chained handler 3412 if (siginfo_flag_set) { 3413 sa = actp->sa_sigaction; 3414 } else { 3415 hand = actp->sa_handler; 3416 } 3417 3418 if ((actp->sa_flags & SA_RESETHAND) != 0) { 3419 actp->sa_handler = SIG_DFL; 3420 } 3421 3422 // try to honor the signal mask 3423 sigset_t oset; 3424 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 3425 3426 // call into the chained handler 3427 if (siginfo_flag_set) { 3428 (*sa)(sig, siginfo, context); 3429 } else { 3430 (*hand)(sig); 3431 } 3432 3433 // restore the signal mask 3434 pthread_sigmask(SIG_SETMASK, &oset, 0); 3435 } 3436 // Tell jvm's signal handler the signal is taken care of. 3437 return true; 3438 } 3439 3440 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 3441 bool chained = false; 3442 // signal-chaining 3443 if (UseSignalChaining) { 3444 struct sigaction *actp = get_chained_signal_action(sig); 3445 if (actp != NULL) { 3446 chained = call_chained_handler(actp, sig, siginfo, context); 3447 } 3448 } 3449 return chained; 3450 } 3451 3452 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 3453 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 3454 return &sigact[sig]; 3455 } 3456 return NULL; 3457 } 3458 3459 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 3460 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3461 sigact[sig] = oldAct; 3462 sigs |= (unsigned int)1 << sig; 3463 } 3464 3465 // for diagnostic 3466 int os::Linux::sigflags[MAXSIGNUM]; 3467 3468 int os::Linux::get_our_sigflags(int sig) { 3469 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3470 return sigflags[sig]; 3471 } 3472 3473 void os::Linux::set_our_sigflags(int sig, int flags) { 3474 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3475 sigflags[sig] = flags; 3476 } 3477 3478 void os::Linux::set_signal_handler(int sig, bool set_installed) { 3479 // Check for overwrite. 3480 struct sigaction oldAct; 3481 sigaction(sig, (struct sigaction*)NULL, &oldAct); 3482 3483 void* oldhand = oldAct.sa_sigaction 3484 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3485 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3486 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 3487 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 3488 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 3489 if (AllowUserSignalHandlers || !set_installed) { 3490 // Do not overwrite; user takes responsibility to forward to us. 3491 return; 3492 } else if (UseSignalChaining) { 3493 // save the old handler in jvm 3494 save_preinstalled_handler(sig, oldAct); 3495 // libjsig also interposes the sigaction() call below and saves the 3496 // old sigaction on it own. 3497 } else { 3498 fatal(err_msg("Encountered unexpected pre-existing sigaction handler " 3499 "%#lx for signal %d.", (long)oldhand, sig)); 3500 } 3501 } 3502 3503 struct sigaction sigAct; 3504 sigfillset(&(sigAct.sa_mask)); 3505 sigAct.sa_handler = SIG_DFL; 3506 if (!set_installed) { 3507 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3508 } else { 3509 sigAct.sa_sigaction = signalHandler; 3510 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3511 } 3512 // Save flags, which are set by ours 3513 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3514 sigflags[sig] = sigAct.sa_flags; 3515 3516 int ret = sigaction(sig, &sigAct, &oldAct); 3517 assert(ret == 0, "check"); 3518 3519 void* oldhand2 = oldAct.sa_sigaction 3520 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3521 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3522 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 3523 } 3524 3525 // install signal handlers for signals that HotSpot needs to 3526 // handle in order to support Java-level exception handling. 3527 3528 void os::Linux::install_signal_handlers() { 3529 if (!signal_handlers_are_installed) { 3530 signal_handlers_are_installed = true; 3531 3532 // signal-chaining 3533 typedef void (*signal_setting_t)(); 3534 signal_setting_t begin_signal_setting = NULL; 3535 signal_setting_t end_signal_setting = NULL; 3536 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3537 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 3538 if (begin_signal_setting != NULL) { 3539 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3540 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 3541 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 3542 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 3543 libjsig_is_loaded = true; 3544 assert(UseSignalChaining, "should enable signal-chaining"); 3545 } 3546 if (libjsig_is_loaded) { 3547 // Tell libjsig jvm is setting signal handlers 3548 (*begin_signal_setting)(); 3549 } 3550 3551 set_signal_handler(SIGSEGV, true); 3552 set_signal_handler(SIGPIPE, true); 3553 set_signal_handler(SIGBUS, true); 3554 set_signal_handler(SIGILL, true); 3555 set_signal_handler(SIGFPE, true); 3556 set_signal_handler(SIGXFSZ, true); 3557 3558 if (libjsig_is_loaded) { 3559 // Tell libjsig jvm finishes setting signal handlers 3560 (*end_signal_setting)(); 3561 } 3562 3563 // We don't activate signal checker if libjsig is in place, we trust ourselves 3564 // and if UserSignalHandler is installed all bets are off 3565 if (CheckJNICalls) { 3566 if (libjsig_is_loaded) { 3567 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 3568 check_signals = false; 3569 } 3570 if (AllowUserSignalHandlers) { 3571 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 3572 check_signals = false; 3573 } 3574 } 3575 } 3576 } 3577 3578 // This is the fastest way to get thread cpu time on Linux. 3579 // Returns cpu time (user+sys) for any thread, not only for current. 3580 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 3581 // It might work on 2.6.10+ with a special kernel/glibc patch. 3582 // For reference, please, see IEEE Std 1003.1-2004: 3583 // http://www.unix.org/single_unix_specification 3584 3585 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 3586 struct timespec tp; 3587 int rc = os::Linux::clock_gettime(clockid, &tp); 3588 assert(rc == 0, "clock_gettime is expected to return 0 code"); 3589 3590 return (tp.tv_sec * SEC_IN_NANOSECS) + tp.tv_nsec; 3591 } 3592 3593 ///// 3594 // glibc on Linux platform uses non-documented flag 3595 // to indicate, that some special sort of signal 3596 // trampoline is used. 3597 // We will never set this flag, and we should 3598 // ignore this flag in our diagnostic 3599 #ifdef SIGNIFICANT_SIGNAL_MASK 3600 #undef SIGNIFICANT_SIGNAL_MASK 3601 #endif 3602 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 3603 3604 static const char* get_signal_handler_name(address handler, 3605 char* buf, int buflen) { 3606 int offset; 3607 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 3608 if (found) { 3609 // skip directory names 3610 const char *p1, *p2; 3611 p1 = buf; 3612 size_t len = strlen(os::file_separator()); 3613 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 3614 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 3615 } else { 3616 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 3617 } 3618 return buf; 3619 } 3620 3621 static void print_signal_handler(outputStream* st, int sig, 3622 char* buf, size_t buflen) { 3623 struct sigaction sa; 3624 3625 sigaction(sig, NULL, &sa); 3626 3627 // See comment for SIGNIFICANT_SIGNAL_MASK define 3628 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 3629 3630 st->print("%s: ", os::exception_name(sig, buf, buflen)); 3631 3632 address handler = (sa.sa_flags & SA_SIGINFO) 3633 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 3634 : CAST_FROM_FN_PTR(address, sa.sa_handler); 3635 3636 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 3637 st->print("SIG_DFL"); 3638 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 3639 st->print("SIG_IGN"); 3640 } else { 3641 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 3642 } 3643 3644 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask); 3645 3646 address rh = VMError::get_resetted_sighandler(sig); 3647 // May be, handler was resetted by VMError? 3648 if(rh != NULL) { 3649 handler = rh; 3650 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 3651 } 3652 3653 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags); 3654 3655 // Check: is it our handler? 3656 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 3657 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 3658 // It is our signal handler 3659 // check for flags, reset system-used one! 3660 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 3661 st->print( 3662 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 3663 os::Linux::get_our_sigflags(sig)); 3664 } 3665 } 3666 st->cr(); 3667 } 3668 3669 3670 #define DO_SIGNAL_CHECK(sig) \ 3671 if (!sigismember(&check_signal_done, sig)) \ 3672 os::Linux::check_signal_handler(sig) 3673 3674 // This method is a periodic task to check for misbehaving JNI applications 3675 // under CheckJNI, we can add any periodic checks here 3676 3677 void os::run_periodic_checks() { 3678 3679 if (check_signals == false) return; 3680 3681 // SEGV and BUS if overridden could potentially prevent 3682 // generation of hs*.log in the event of a crash, debugging 3683 // such a case can be very challenging, so we absolutely 3684 // check the following for a good measure: 3685 DO_SIGNAL_CHECK(SIGSEGV); 3686 DO_SIGNAL_CHECK(SIGILL); 3687 DO_SIGNAL_CHECK(SIGFPE); 3688 DO_SIGNAL_CHECK(SIGBUS); 3689 DO_SIGNAL_CHECK(SIGPIPE); 3690 DO_SIGNAL_CHECK(SIGXFSZ); 3691 3692 3693 // ReduceSignalUsage allows the user to override these handlers 3694 // see comments at the very top and jvm_solaris.h 3695 if (!ReduceSignalUsage) { 3696 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 3697 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 3698 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 3699 DO_SIGNAL_CHECK(BREAK_SIGNAL); 3700 } 3701 3702 DO_SIGNAL_CHECK(SR_signum); 3703 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 3704 } 3705 3706 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 3707 3708 static os_sigaction_t os_sigaction = NULL; 3709 3710 void os::Linux::check_signal_handler(int sig) { 3711 char buf[O_BUFLEN]; 3712 address jvmHandler = NULL; 3713 3714 3715 struct sigaction act; 3716 if (os_sigaction == NULL) { 3717 // only trust the default sigaction, in case it has been interposed 3718 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 3719 if (os_sigaction == NULL) return; 3720 } 3721 3722 os_sigaction(sig, (struct sigaction*)NULL, &act); 3723 3724 3725 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 3726 3727 address thisHandler = (act.sa_flags & SA_SIGINFO) 3728 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 3729 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 3730 3731 3732 switch(sig) { 3733 case SIGSEGV: 3734 case SIGBUS: 3735 case SIGFPE: 3736 case SIGPIPE: 3737 case SIGILL: 3738 case SIGXFSZ: 3739 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 3740 break; 3741 3742 case SHUTDOWN1_SIGNAL: 3743 case SHUTDOWN2_SIGNAL: 3744 case SHUTDOWN3_SIGNAL: 3745 case BREAK_SIGNAL: 3746 jvmHandler = (address)user_handler(); 3747 break; 3748 3749 case INTERRUPT_SIGNAL: 3750 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 3751 break; 3752 3753 default: 3754 if (sig == SR_signum) { 3755 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 3756 } else { 3757 return; 3758 } 3759 break; 3760 } 3761 3762 if (thisHandler != jvmHandler) { 3763 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 3764 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 3765 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 3766 // No need to check this sig any longer 3767 sigaddset(&check_signal_done, sig); 3768 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 3769 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 3770 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 3771 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 3772 // No need to check this sig any longer 3773 sigaddset(&check_signal_done, sig); 3774 } 3775 3776 // Dump all the signal 3777 if (sigismember(&check_signal_done, sig)) { 3778 print_signal_handlers(tty, buf, O_BUFLEN); 3779 } 3780 } 3781 3782 extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 3783 3784 extern bool signal_name(int signo, char* buf, size_t len); 3785 3786 const char* os::exception_name(int exception_code, char* buf, size_t size) { 3787 if (0 < exception_code && exception_code <= SIGRTMAX) { 3788 // signal 3789 if (!signal_name(exception_code, buf, size)) { 3790 jio_snprintf(buf, size, "SIG%d", exception_code); 3791 } 3792 return buf; 3793 } else { 3794 return NULL; 3795 } 3796 } 3797 3798 // this is called _before_ the most of global arguments have been parsed 3799 void os::init(void) { 3800 char dummy; /* used to get a guess on initial stack address */ 3801 // first_hrtime = gethrtime(); 3802 3803 // With LinuxThreads the JavaMain thread pid (primordial thread) 3804 // is different than the pid of the java launcher thread. 3805 // So, on Linux, the launcher thread pid is passed to the VM 3806 // via the sun.java.launcher.pid property. 3807 // Use this property instead of getpid() if it was correctly passed. 3808 // See bug 6351349. 3809 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 3810 3811 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 3812 3813 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 3814 3815 init_random(1234567); 3816 3817 ThreadCritical::initialize(); 3818 3819 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 3820 if (Linux::page_size() == -1) { 3821 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)", 3822 strerror(errno))); 3823 } 3824 init_page_sizes((size_t) Linux::page_size()); 3825 3826 Linux::initialize_system_info(); 3827 3828 // main_thread points to the aboriginal thread 3829 Linux::_main_thread = pthread_self(); 3830 3831 Linux::clock_init(); 3832 initial_time_count = os::elapsed_counter(); 3833 pthread_mutex_init(&dl_mutex, NULL); 3834 } 3835 3836 // To install functions for atexit system call 3837 extern "C" { 3838 static void perfMemory_exit_helper() { 3839 perfMemory_exit(); 3840 } 3841 } 3842 3843 // this is called _after_ the global arguments have been parsed 3844 jint os::init_2(void) 3845 { 3846 Linux::fast_thread_clock_init(); 3847 3848 if (StackShadowPages <= 0) { 3849 tty->print_cr("\nThe -XX:StackShadowPages parameter must be set to positive value!"); 3850 return JNI_ERR; 3851 } 3852 3853 // Allocate a single page and mark it as readable for safepoint polling 3854 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 3855 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 3856 3857 os::set_polling_page( polling_page ); 3858 3859 #ifndef PRODUCT 3860 if(Verbose && PrintMiscellaneous) 3861 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 3862 #endif 3863 3864 if (!UseMembar) { 3865 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 3866 guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page"); 3867 os::set_memory_serialize_page( mem_serialize_page ); 3868 3869 #ifndef PRODUCT 3870 if(Verbose && PrintMiscellaneous) 3871 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 3872 #endif 3873 } 3874 3875 FLAG_SET_DEFAULT(UseLargePages, os::large_page_init()); 3876 3877 // initialize suspend/resume support - must do this before signal_sets_init() 3878 if (SR_initialize() != 0) { 3879 perror("SR_initialize failed"); 3880 return JNI_ERR; 3881 } 3882 3883 Linux::signal_sets_init(); 3884 Linux::install_signal_handlers(); 3885 3886 size_t threadStackSizeInBytes = ThreadStackSize * K; 3887 if (threadStackSizeInBytes != 0 && 3888 threadStackSizeInBytes < Linux::min_stack_allowed) { 3889 tty->print_cr("\nThe stack size specified is too small, " 3890 "Specify at least %dk", 3891 Linux::min_stack_allowed / K); 3892 return JNI_ERR; 3893 } 3894 3895 // Make the stack size a multiple of the page size so that 3896 // the yellow/red zones can be guarded. 3897 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 3898 vm_page_size())); 3899 3900 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 3901 3902 Linux::libpthread_init(); 3903 if (PrintMiscellaneous && (Verbose || WizardMode)) { 3904 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 3905 Linux::glibc_version(), Linux::libpthread_version(), 3906 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 3907 } 3908 3909 if (UseNUMA) { 3910 if (!Linux::libnuma_init()) { 3911 UseNUMA = false; 3912 } else { 3913 if ((Linux::numa_max_node() < 1)) { 3914 // There's only one node(they start from 0), disable NUMA. 3915 UseNUMA = false; 3916 } 3917 } 3918 if (!UseNUMA && ForceNUMA) { 3919 UseNUMA = true; 3920 } 3921 } 3922 3923 if (MaxFDLimit) { 3924 // set the number of file descriptors to max. print out error 3925 // if getrlimit/setrlimit fails but continue regardless. 3926 struct rlimit nbr_files; 3927 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 3928 if (status != 0) { 3929 if (PrintMiscellaneous && (Verbose || WizardMode)) 3930 perror("os::init_2 getrlimit failed"); 3931 } else { 3932 nbr_files.rlim_cur = nbr_files.rlim_max; 3933 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 3934 if (status != 0) { 3935 if (PrintMiscellaneous && (Verbose || WizardMode)) 3936 perror("os::init_2 setrlimit failed"); 3937 } 3938 } 3939 } 3940 3941 // Initialize lock used to serialize thread creation (see os::create_thread) 3942 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 3943 3944 // Initialize HPI. 3945 jint hpi_result = hpi::initialize(); 3946 if (hpi_result != JNI_OK) { 3947 tty->print_cr("There was an error trying to initialize the HPI library."); 3948 return hpi_result; 3949 } 3950 3951 // at-exit methods are called in the reverse order of their registration. 3952 // atexit functions are called on return from main or as a result of a 3953 // call to exit(3C). There can be only 32 of these functions registered 3954 // and atexit() does not set errno. 3955 3956 if (PerfAllowAtExitRegistration) { 3957 // only register atexit functions if PerfAllowAtExitRegistration is set. 3958 // atexit functions can be delayed until process exit time, which 3959 // can be problematic for embedded VM situations. Embedded VMs should 3960 // call DestroyJavaVM() to assure that VM resources are released. 3961 3962 // note: perfMemory_exit_helper atexit function may be removed in 3963 // the future if the appropriate cleanup code can be added to the 3964 // VM_Exit VMOperation's doit method. 3965 if (atexit(perfMemory_exit_helper) != 0) { 3966 warning("os::init2 atexit(perfMemory_exit_helper) failed"); 3967 } 3968 } 3969 3970 // initialize thread priority policy 3971 prio_init(); 3972 3973 return JNI_OK; 3974 } 3975 3976 // Mark the polling page as unreadable 3977 void os::make_polling_page_unreadable(void) { 3978 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 3979 fatal("Could not disable polling page"); 3980 }; 3981 3982 // Mark the polling page as readable 3983 void os::make_polling_page_readable(void) { 3984 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 3985 fatal("Could not enable polling page"); 3986 } 3987 }; 3988 3989 int os::active_processor_count() { 3990 // Linux doesn't yet have a (official) notion of processor sets, 3991 // so just return the number of online processors. 3992 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 3993 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 3994 return online_cpus; 3995 } 3996 3997 bool os::distribute_processes(uint length, uint* distribution) { 3998 // Not yet implemented. 3999 return false; 4000 } 4001 4002 bool os::bind_to_processor(uint processor_id) { 4003 // Not yet implemented. 4004 return false; 4005 } 4006 4007 /// 4008 4009 // Suspends the target using the signal mechanism and then grabs the PC before 4010 // resuming the target. Used by the flat-profiler only 4011 ExtendedPC os::get_thread_pc(Thread* thread) { 4012 // Make sure that it is called by the watcher for the VMThread 4013 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 4014 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 4015 4016 ExtendedPC epc; 4017 4018 OSThread* osthread = thread->osthread(); 4019 if (do_suspend(osthread)) { 4020 if (osthread->ucontext() != NULL) { 4021 epc = os::Linux::ucontext_get_pc(osthread->ucontext()); 4022 } else { 4023 // NULL context is unexpected, double-check this is the VMThread 4024 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 4025 } 4026 do_resume(osthread); 4027 } 4028 // failure means pthread_kill failed for some reason - arguably this is 4029 // a fatal problem, but such problems are ignored elsewhere 4030 4031 return epc; 4032 } 4033 4034 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 4035 { 4036 if (is_NPTL()) { 4037 return pthread_cond_timedwait(_cond, _mutex, _abstime); 4038 } else { 4039 #ifndef IA64 4040 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 4041 // word back to default 64bit precision if condvar is signaled. Java 4042 // wants 53bit precision. Save and restore current value. 4043 int fpu = get_fpu_control_word(); 4044 #endif // IA64 4045 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 4046 #ifndef IA64 4047 set_fpu_control_word(fpu); 4048 #endif // IA64 4049 return status; 4050 } 4051 } 4052 4053 //////////////////////////////////////////////////////////////////////////////// 4054 // debug support 4055 4056 #ifndef PRODUCT 4057 static address same_page(address x, address y) { 4058 int page_bits = -os::vm_page_size(); 4059 if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits)) 4060 return x; 4061 else if (x > y) 4062 return (address)(intptr_t(y) | ~page_bits) + 1; 4063 else 4064 return (address)(intptr_t(y) & page_bits); 4065 } 4066 4067 bool os::find(address addr) { 4068 Dl_info dlinfo; 4069 memset(&dlinfo, 0, sizeof(dlinfo)); 4070 if (dladdr(addr, &dlinfo)) { 4071 tty->print(PTR_FORMAT ": ", addr); 4072 if (dlinfo.dli_sname != NULL) { 4073 tty->print("%s+%#x", dlinfo.dli_sname, 4074 addr - (intptr_t)dlinfo.dli_saddr); 4075 } else if (dlinfo.dli_fname) { 4076 tty->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 4077 } else { 4078 tty->print("<absolute address>"); 4079 } 4080 if (dlinfo.dli_fname) { 4081 tty->print(" in %s", dlinfo.dli_fname); 4082 } 4083 if (dlinfo.dli_fbase) { 4084 tty->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 4085 } 4086 tty->cr(); 4087 4088 if (Verbose) { 4089 // decode some bytes around the PC 4090 address begin = same_page(addr-40, addr); 4091 address end = same_page(addr+40, addr); 4092 address lowest = (address) dlinfo.dli_sname; 4093 if (!lowest) lowest = (address) dlinfo.dli_fbase; 4094 if (begin < lowest) begin = lowest; 4095 Dl_info dlinfo2; 4096 if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr 4097 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 4098 end = (address) dlinfo2.dli_saddr; 4099 Disassembler::decode(begin, end); 4100 } 4101 return true; 4102 } 4103 return false; 4104 } 4105 4106 #endif 4107 4108 //////////////////////////////////////////////////////////////////////////////// 4109 // misc 4110 4111 // This does not do anything on Linux. This is basically a hook for being 4112 // able to use structured exception handling (thread-local exception filters) 4113 // on, e.g., Win32. 4114 void 4115 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 4116 JavaCallArguments* args, Thread* thread) { 4117 f(value, method, args, thread); 4118 } 4119 4120 void os::print_statistics() { 4121 } 4122 4123 int os::message_box(const char* title, const char* message) { 4124 int i; 4125 fdStream err(defaultStream::error_fd()); 4126 for (i = 0; i < 78; i++) err.print_raw("="); 4127 err.cr(); 4128 err.print_raw_cr(title); 4129 for (i = 0; i < 78; i++) err.print_raw("-"); 4130 err.cr(); 4131 err.print_raw_cr(message); 4132 for (i = 0; i < 78; i++) err.print_raw("="); 4133 err.cr(); 4134 4135 char buf[16]; 4136 // Prevent process from exiting upon "read error" without consuming all CPU 4137 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 4138 4139 return buf[0] == 'y' || buf[0] == 'Y'; 4140 } 4141 4142 int os::stat(const char *path, struct stat *sbuf) { 4143 char pathbuf[MAX_PATH]; 4144 if (strlen(path) > MAX_PATH - 1) { 4145 errno = ENAMETOOLONG; 4146 return -1; 4147 } 4148 hpi::native_path(strcpy(pathbuf, path)); 4149 return ::stat(pathbuf, sbuf); 4150 } 4151 4152 bool os::check_heap(bool force) { 4153 return true; 4154 } 4155 4156 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 4157 return ::vsnprintf(buf, count, format, args); 4158 } 4159 4160 // Is a (classpath) directory empty? 4161 bool os::dir_is_empty(const char* path) { 4162 DIR *dir = NULL; 4163 struct dirent *ptr; 4164 4165 dir = opendir(path); 4166 if (dir == NULL) return true; 4167 4168 /* Scan the directory */ 4169 bool result = true; 4170 char buf[sizeof(struct dirent) + MAX_PATH]; 4171 while (result && (ptr = ::readdir(dir)) != NULL) { 4172 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 4173 result = false; 4174 } 4175 } 4176 closedir(dir); 4177 return result; 4178 } 4179 4180 // create binary file, rewriting existing file if required 4181 int os::create_binary_file(const char* path, bool rewrite_existing) { 4182 int oflags = O_WRONLY | O_CREAT; 4183 if (!rewrite_existing) { 4184 oflags |= O_EXCL; 4185 } 4186 return ::open64(path, oflags, S_IREAD | S_IWRITE); 4187 } 4188 4189 // return current position of file pointer 4190 jlong os::current_file_offset(int fd) { 4191 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 4192 } 4193 4194 // move file pointer to the specified offset 4195 jlong os::seek_to_file_offset(int fd, jlong offset) { 4196 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 4197 } 4198 4199 // Map a block of memory. 4200 char* os::map_memory(int fd, const char* file_name, size_t file_offset, 4201 char *addr, size_t bytes, bool read_only, 4202 bool allow_exec) { 4203 int prot; 4204 int flags; 4205 4206 if (read_only) { 4207 prot = PROT_READ; 4208 flags = MAP_SHARED; 4209 } else { 4210 prot = PROT_READ | PROT_WRITE; 4211 flags = MAP_PRIVATE; 4212 } 4213 4214 if (allow_exec) { 4215 prot |= PROT_EXEC; 4216 } 4217 4218 if (addr != NULL) { 4219 flags |= MAP_FIXED; 4220 } 4221 4222 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 4223 fd, file_offset); 4224 if (mapped_address == MAP_FAILED) { 4225 return NULL; 4226 } 4227 return mapped_address; 4228 } 4229 4230 4231 // Remap a block of memory. 4232 char* os::remap_memory(int fd, const char* file_name, size_t file_offset, 4233 char *addr, size_t bytes, bool read_only, 4234 bool allow_exec) { 4235 // same as map_memory() on this OS 4236 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 4237 allow_exec); 4238 } 4239 4240 4241 // Unmap a block of memory. 4242 bool os::unmap_memory(char* addr, size_t bytes) { 4243 return munmap(addr, bytes) == 0; 4244 } 4245 4246 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 4247 4248 static clockid_t thread_cpu_clockid(Thread* thread) { 4249 pthread_t tid = thread->osthread()->pthread_id(); 4250 clockid_t clockid; 4251 4252 // Get thread clockid 4253 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 4254 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 4255 return clockid; 4256 } 4257 4258 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 4259 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 4260 // of a thread. 4261 // 4262 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 4263 // the fast estimate available on the platform. 4264 4265 jlong os::current_thread_cpu_time() { 4266 if (os::Linux::supports_fast_thread_cpu_time()) { 4267 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4268 } else { 4269 // return user + sys since the cost is the same 4270 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 4271 } 4272 } 4273 4274 jlong os::thread_cpu_time(Thread* thread) { 4275 // consistent with what current_thread_cpu_time() returns 4276 if (os::Linux::supports_fast_thread_cpu_time()) { 4277 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4278 } else { 4279 return slow_thread_cpu_time(thread, true /* user + sys */); 4280 } 4281 } 4282 4283 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 4284 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4285 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4286 } else { 4287 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 4288 } 4289 } 4290 4291 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4292 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4293 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4294 } else { 4295 return slow_thread_cpu_time(thread, user_sys_cpu_time); 4296 } 4297 } 4298 4299 // 4300 // -1 on error. 4301 // 4302 4303 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4304 static bool proc_pid_cpu_avail = true; 4305 static bool proc_task_unchecked = true; 4306 static const char *proc_stat_path = "/proc/%d/stat"; 4307 pid_t tid = thread->osthread()->thread_id(); 4308 int i; 4309 char *s; 4310 char stat[2048]; 4311 int statlen; 4312 char proc_name[64]; 4313 int count; 4314 long sys_time, user_time; 4315 char string[64]; 4316 int idummy; 4317 long ldummy; 4318 FILE *fp; 4319 4320 // We first try accessing /proc/<pid>/cpu since this is faster to 4321 // process. If this file is not present (linux kernels 2.5 and above) 4322 // then we open /proc/<pid>/stat. 4323 if ( proc_pid_cpu_avail ) { 4324 sprintf(proc_name, "/proc/%d/cpu", tid); 4325 fp = fopen(proc_name, "r"); 4326 if ( fp != NULL ) { 4327 count = fscanf( fp, "%s %lu %lu\n", string, &user_time, &sys_time); 4328 fclose(fp); 4329 if ( count != 3 ) return -1; 4330 4331 if (user_sys_cpu_time) { 4332 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 4333 } else { 4334 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 4335 } 4336 } 4337 else proc_pid_cpu_avail = false; 4338 } 4339 4340 // The /proc/<tid>/stat aggregates per-process usage on 4341 // new Linux kernels 2.6+ where NPTL is supported. 4342 // The /proc/self/task/<tid>/stat still has the per-thread usage. 4343 // See bug 6328462. 4344 // There can be no directory /proc/self/task on kernels 2.4 with NPTL 4345 // and possibly in some other cases, so we check its availability. 4346 if (proc_task_unchecked && os::Linux::is_NPTL()) { 4347 // This is executed only once 4348 proc_task_unchecked = false; 4349 fp = fopen("/proc/self/task", "r"); 4350 if (fp != NULL) { 4351 proc_stat_path = "/proc/self/task/%d/stat"; 4352 fclose(fp); 4353 } 4354 } 4355 4356 sprintf(proc_name, proc_stat_path, tid); 4357 fp = fopen(proc_name, "r"); 4358 if ( fp == NULL ) return -1; 4359 statlen = fread(stat, 1, 2047, fp); 4360 stat[statlen] = '\0'; 4361 fclose(fp); 4362 4363 // Skip pid and the command string. Note that we could be dealing with 4364 // weird command names, e.g. user could decide to rename java launcher 4365 // to "java 1.4.2 :)", then the stat file would look like 4366 // 1234 (java 1.4.2 :)) R ... ... 4367 // We don't really need to know the command string, just find the last 4368 // occurrence of ")" and then start parsing from there. See bug 4726580. 4369 s = strrchr(stat, ')'); 4370 i = 0; 4371 if (s == NULL ) return -1; 4372 4373 // Skip blank chars 4374 do s++; while (isspace(*s)); 4375 4376 count = sscanf(s,"%*c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 4377 &idummy, &idummy, &idummy, &idummy, &idummy, 4378 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 4379 &user_time, &sys_time); 4380 if ( count != 12 ) return -1; 4381 if (user_sys_cpu_time) { 4382 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 4383 } else { 4384 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 4385 } 4386 } 4387 4388 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4389 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4390 info_ptr->may_skip_backward = false; // elapsed time not wall time 4391 info_ptr->may_skip_forward = false; // elapsed time not wall time 4392 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4393 } 4394 4395 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4396 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4397 info_ptr->may_skip_backward = false; // elapsed time not wall time 4398 info_ptr->may_skip_forward = false; // elapsed time not wall time 4399 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4400 } 4401 4402 bool os::is_thread_cpu_time_supported() { 4403 return true; 4404 } 4405 4406 // System loadavg support. Returns -1 if load average cannot be obtained. 4407 // Linux doesn't yet have a (official) notion of processor sets, 4408 // so just return the system wide load average. 4409 int os::loadavg(double loadavg[], int nelem) { 4410 return ::getloadavg(loadavg, nelem); 4411 } 4412 4413 void os::pause() { 4414 char filename[MAX_PATH]; 4415 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 4416 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 4417 } else { 4418 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 4419 } 4420 4421 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 4422 if (fd != -1) { 4423 struct stat buf; 4424 close(fd); 4425 while (::stat(filename, &buf) == 0) { 4426 (void)::poll(NULL, 0, 100); 4427 } 4428 } else { 4429 jio_fprintf(stderr, 4430 "Could not open pause file '%s', continuing immediately.\n", filename); 4431 } 4432 } 4433 4434 extern "C" { 4435 4436 /** 4437 * NOTE: the following code is to keep the green threads code 4438 * in the libjava.so happy. Once the green threads is removed, 4439 * these code will no longer be needed. 4440 */ 4441 int 4442 jdk_waitpid(pid_t pid, int* status, int options) { 4443 return waitpid(pid, status, options); 4444 } 4445 4446 int 4447 fork1() { 4448 return fork(); 4449 } 4450 4451 int 4452 jdk_sem_init(sem_t *sem, int pshared, unsigned int value) { 4453 return sem_init(sem, pshared, value); 4454 } 4455 4456 int 4457 jdk_sem_post(sem_t *sem) { 4458 return sem_post(sem); 4459 } 4460 4461 int 4462 jdk_sem_wait(sem_t *sem) { 4463 return sem_wait(sem); 4464 } 4465 4466 int 4467 jdk_pthread_sigmask(int how , const sigset_t* newmask, sigset_t* oldmask) { 4468 return pthread_sigmask(how , newmask, oldmask); 4469 } 4470 4471 } 4472 4473 // Refer to the comments in os_solaris.cpp park-unpark. 4474 // 4475 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 4476 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 4477 // For specifics regarding the bug see GLIBC BUGID 261237 : 4478 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 4479 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 4480 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 4481 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 4482 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 4483 // and monitorenter when we're using 1-0 locking. All those operations may result in 4484 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 4485 // of libpthread avoids the problem, but isn't practical. 4486 // 4487 // Possible remedies: 4488 // 4489 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 4490 // This is palliative and probabilistic, however. If the thread is preempted 4491 // between the call to compute_abstime() and pthread_cond_timedwait(), more 4492 // than the minimum period may have passed, and the abstime may be stale (in the 4493 // past) resultin in a hang. Using this technique reduces the odds of a hang 4494 // but the JVM is still vulnerable, particularly on heavily loaded systems. 4495 // 4496 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 4497 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 4498 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 4499 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 4500 // thread. 4501 // 4502 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 4503 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 4504 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 4505 // This also works well. In fact it avoids kernel-level scalability impediments 4506 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 4507 // timers in a graceful fashion. 4508 // 4509 // 4. When the abstime value is in the past it appears that control returns 4510 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 4511 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 4512 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 4513 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 4514 // It may be possible to avoid reinitialization by checking the return 4515 // value from pthread_cond_timedwait(). In addition to reinitializing the 4516 // condvar we must establish the invariant that cond_signal() is only called 4517 // within critical sections protected by the adjunct mutex. This prevents 4518 // cond_signal() from "seeing" a condvar that's in the midst of being 4519 // reinitialized or that is corrupt. Sadly, this invariant obviates the 4520 // desirable signal-after-unlock optimization that avoids futile context switching. 4521 // 4522 // I'm also concerned that some versions of NTPL might allocate an auxilliary 4523 // structure when a condvar is used or initialized. cond_destroy() would 4524 // release the helper structure. Our reinitialize-after-timedwait fix 4525 // put excessive stress on malloc/free and locks protecting the c-heap. 4526 // 4527 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 4528 // It may be possible to refine (4) by checking the kernel and NTPL verisons 4529 // and only enabling the work-around for vulnerable environments. 4530 4531 // utility to compute the abstime argument to timedwait: 4532 // millis is the relative timeout time 4533 // abstime will be the absolute timeout time 4534 // TODO: replace compute_abstime() with unpackTime() 4535 4536 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 4537 if (millis < 0) millis = 0; 4538 struct timeval now; 4539 int status = gettimeofday(&now, NULL); 4540 assert(status == 0, "gettimeofday"); 4541 jlong seconds = millis / 1000; 4542 millis %= 1000; 4543 if (seconds > 50000000) { // see man cond_timedwait(3T) 4544 seconds = 50000000; 4545 } 4546 abstime->tv_sec = now.tv_sec + seconds; 4547 long usec = now.tv_usec + millis * 1000; 4548 if (usec >= 1000000) { 4549 abstime->tv_sec += 1; 4550 usec -= 1000000; 4551 } 4552 abstime->tv_nsec = usec * 1000; 4553 return abstime; 4554 } 4555 4556 4557 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 4558 // Conceptually TryPark() should be equivalent to park(0). 4559 4560 int os::PlatformEvent::TryPark() { 4561 for (;;) { 4562 const int v = _Event ; 4563 guarantee ((v == 0) || (v == 1), "invariant") ; 4564 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 4565 } 4566 } 4567 4568 void os::PlatformEvent::park() { // AKA "down()" 4569 // Invariant: Only the thread associated with the Event/PlatformEvent 4570 // may call park(). 4571 // TODO: assert that _Assoc != NULL or _Assoc == Self 4572 int v ; 4573 for (;;) { 4574 v = _Event ; 4575 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 4576 } 4577 guarantee (v >= 0, "invariant") ; 4578 if (v == 0) { 4579 // Do this the hard way by blocking ... 4580 int status = pthread_mutex_lock(_mutex); 4581 assert_status(status == 0, status, "mutex_lock"); 4582 guarantee (_nParked == 0, "invariant") ; 4583 ++ _nParked ; 4584 while (_Event < 0) { 4585 status = pthread_cond_wait(_cond, _mutex); 4586 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 4587 // Treat this the same as if the wait was interrupted 4588 if (status == ETIME) { status = EINTR; } 4589 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 4590 } 4591 -- _nParked ; 4592 4593 // In theory we could move the ST of 0 into _Event past the unlock(), 4594 // but then we'd need a MEMBAR after the ST. 4595 _Event = 0 ; 4596 status = pthread_mutex_unlock(_mutex); 4597 assert_status(status == 0, status, "mutex_unlock"); 4598 } 4599 guarantee (_Event >= 0, "invariant") ; 4600 } 4601 4602 int os::PlatformEvent::park(jlong millis) { 4603 guarantee (_nParked == 0, "invariant") ; 4604 4605 int v ; 4606 for (;;) { 4607 v = _Event ; 4608 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 4609 } 4610 guarantee (v >= 0, "invariant") ; 4611 if (v != 0) return OS_OK ; 4612 4613 // We do this the hard way, by blocking the thread. 4614 // Consider enforcing a minimum timeout value. 4615 struct timespec abst; 4616 compute_abstime(&abst, millis); 4617 4618 int ret = OS_TIMEOUT; 4619 int status = pthread_mutex_lock(_mutex); 4620 assert_status(status == 0, status, "mutex_lock"); 4621 guarantee (_nParked == 0, "invariant") ; 4622 ++_nParked ; 4623 4624 // Object.wait(timo) will return because of 4625 // (a) notification 4626 // (b) timeout 4627 // (c) thread.interrupt 4628 // 4629 // Thread.interrupt and object.notify{All} both call Event::set. 4630 // That is, we treat thread.interrupt as a special case of notification. 4631 // The underlying Solaris implementation, cond_timedwait, admits 4632 // spurious/premature wakeups, but the JLS/JVM spec prevents the 4633 // JVM from making those visible to Java code. As such, we must 4634 // filter out spurious wakeups. We assume all ETIME returns are valid. 4635 // 4636 // TODO: properly differentiate simultaneous notify+interrupt. 4637 // In that case, we should propagate the notify to another waiter. 4638 4639 while (_Event < 0) { 4640 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 4641 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 4642 pthread_cond_destroy (_cond); 4643 pthread_cond_init (_cond, NULL) ; 4644 } 4645 assert_status(status == 0 || status == EINTR || 4646 status == ETIME || status == ETIMEDOUT, 4647 status, "cond_timedwait"); 4648 if (!FilterSpuriousWakeups) break ; // previous semantics 4649 if (status == ETIME || status == ETIMEDOUT) break ; 4650 // We consume and ignore EINTR and spurious wakeups. 4651 } 4652 --_nParked ; 4653 if (_Event >= 0) { 4654 ret = OS_OK; 4655 } 4656 _Event = 0 ; 4657 status = pthread_mutex_unlock(_mutex); 4658 assert_status(status == 0, status, "mutex_unlock"); 4659 assert (_nParked == 0, "invariant") ; 4660 return ret; 4661 } 4662 4663 void os::PlatformEvent::unpark() { 4664 int v, AnyWaiters ; 4665 for (;;) { 4666 v = _Event ; 4667 if (v > 0) { 4668 // The LD of _Event could have reordered or be satisfied 4669 // by a read-aside from this processor's write buffer. 4670 // To avoid problems execute a barrier and then 4671 // ratify the value. 4672 OrderAccess::fence() ; 4673 if (_Event == v) return ; 4674 continue ; 4675 } 4676 if (Atomic::cmpxchg (v+1, &_Event, v) == v) break ; 4677 } 4678 if (v < 0) { 4679 // Wait for the thread associated with the event to vacate 4680 int status = pthread_mutex_lock(_mutex); 4681 assert_status(status == 0, status, "mutex_lock"); 4682 AnyWaiters = _nParked ; 4683 assert (AnyWaiters == 0 || AnyWaiters == 1, "invariant") ; 4684 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 4685 AnyWaiters = 0 ; 4686 pthread_cond_signal (_cond); 4687 } 4688 status = pthread_mutex_unlock(_mutex); 4689 assert_status(status == 0, status, "mutex_unlock"); 4690 if (AnyWaiters != 0) { 4691 status = pthread_cond_signal(_cond); 4692 assert_status(status == 0, status, "cond_signal"); 4693 } 4694 } 4695 4696 // Note that we signal() _after dropping the lock for "immortal" Events. 4697 // This is safe and avoids a common class of futile wakeups. In rare 4698 // circumstances this can cause a thread to return prematurely from 4699 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 4700 // simply re-test the condition and re-park itself. 4701 } 4702 4703 4704 // JSR166 4705 // ------------------------------------------------------- 4706 4707 /* 4708 * The solaris and linux implementations of park/unpark are fairly 4709 * conservative for now, but can be improved. They currently use a 4710 * mutex/condvar pair, plus a a count. 4711 * Park decrements count if > 0, else does a condvar wait. Unpark 4712 * sets count to 1 and signals condvar. Only one thread ever waits 4713 * on the condvar. Contention seen when trying to park implies that someone 4714 * is unparking you, so don't wait. And spurious returns are fine, so there 4715 * is no need to track notifications. 4716 */ 4717 4718 4719 #define NANOSECS_PER_SEC 1000000000 4720 #define NANOSECS_PER_MILLISEC 1000000 4721 #define MAX_SECS 100000000 4722 /* 4723 * This code is common to linux and solaris and will be moved to a 4724 * common place in dolphin. 4725 * 4726 * The passed in time value is either a relative time in nanoseconds 4727 * or an absolute time in milliseconds. Either way it has to be unpacked 4728 * into suitable seconds and nanoseconds components and stored in the 4729 * given timespec structure. 4730 * Given time is a 64-bit value and the time_t used in the timespec is only 4731 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 4732 * overflow if times way in the future are given. Further on Solaris versions 4733 * prior to 10 there is a restriction (see cond_timedwait) that the specified 4734 * number of seconds, in abstime, is less than current_time + 100,000,000. 4735 * As it will be 28 years before "now + 100000000" will overflow we can 4736 * ignore overflow and just impose a hard-limit on seconds using the value 4737 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 4738 * years from "now". 4739 */ 4740 4741 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 4742 assert (time > 0, "convertTime"); 4743 4744 struct timeval now; 4745 int status = gettimeofday(&now, NULL); 4746 assert(status == 0, "gettimeofday"); 4747 4748 time_t max_secs = now.tv_sec + MAX_SECS; 4749 4750 if (isAbsolute) { 4751 jlong secs = time / 1000; 4752 if (secs > max_secs) { 4753 absTime->tv_sec = max_secs; 4754 } 4755 else { 4756 absTime->tv_sec = secs; 4757 } 4758 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 4759 } 4760 else { 4761 jlong secs = time / NANOSECS_PER_SEC; 4762 if (secs >= MAX_SECS) { 4763 absTime->tv_sec = max_secs; 4764 absTime->tv_nsec = 0; 4765 } 4766 else { 4767 absTime->tv_sec = now.tv_sec + secs; 4768 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 4769 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 4770 absTime->tv_nsec -= NANOSECS_PER_SEC; 4771 ++absTime->tv_sec; // note: this must be <= max_secs 4772 } 4773 } 4774 } 4775 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 4776 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 4777 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 4778 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 4779 } 4780 4781 void Parker::park(bool isAbsolute, jlong time) { 4782 // Optional fast-path check: 4783 // Return immediately if a permit is available. 4784 if (_counter > 0) { 4785 _counter = 0 ; 4786 OrderAccess::fence(); 4787 return ; 4788 } 4789 4790 Thread* thread = Thread::current(); 4791 assert(thread->is_Java_thread(), "Must be JavaThread"); 4792 JavaThread *jt = (JavaThread *)thread; 4793 4794 // Optional optimization -- avoid state transitions if there's an interrupt pending. 4795 // Check interrupt before trying to wait 4796 if (Thread::is_interrupted(thread, false)) { 4797 return; 4798 } 4799 4800 // Next, demultiplex/decode time arguments 4801 timespec absTime; 4802 if (time < 0) { // don't wait at all 4803 return; 4804 } 4805 if (time > 0) { 4806 unpackTime(&absTime, isAbsolute, time); 4807 } 4808 4809 4810 // Enter safepoint region 4811 // Beware of deadlocks such as 6317397. 4812 // The per-thread Parker:: mutex is a classic leaf-lock. 4813 // In particular a thread must never block on the Threads_lock while 4814 // holding the Parker:: mutex. If safepoints are pending both the 4815 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 4816 ThreadBlockInVM tbivm(jt); 4817 4818 // Don't wait if cannot get lock since interference arises from 4819 // unblocking. Also. check interrupt before trying wait 4820 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 4821 return; 4822 } 4823 4824 int status ; 4825 if (_counter > 0) { // no wait needed 4826 _counter = 0; 4827 status = pthread_mutex_unlock(_mutex); 4828 assert (status == 0, "invariant") ; 4829 OrderAccess::fence(); 4830 return; 4831 } 4832 4833 #ifdef ASSERT 4834 // Don't catch signals while blocked; let the running threads have the signals. 4835 // (This allows a debugger to break into the running thread.) 4836 sigset_t oldsigs; 4837 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 4838 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 4839 #endif 4840 4841 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 4842 jt->set_suspend_equivalent(); 4843 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 4844 4845 if (time == 0) { 4846 status = pthread_cond_wait (_cond, _mutex) ; 4847 } else { 4848 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ; 4849 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 4850 pthread_cond_destroy (_cond) ; 4851 pthread_cond_init (_cond, NULL); 4852 } 4853 } 4854 assert_status(status == 0 || status == EINTR || 4855 status == ETIME || status == ETIMEDOUT, 4856 status, "cond_timedwait"); 4857 4858 #ifdef ASSERT 4859 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 4860 #endif 4861 4862 _counter = 0 ; 4863 status = pthread_mutex_unlock(_mutex) ; 4864 assert_status(status == 0, status, "invariant") ; 4865 // If externally suspended while waiting, re-suspend 4866 if (jt->handle_special_suspend_equivalent_condition()) { 4867 jt->java_suspend_self(); 4868 } 4869 4870 OrderAccess::fence(); 4871 } 4872 4873 void Parker::unpark() { 4874 int s, status ; 4875 status = pthread_mutex_lock(_mutex); 4876 assert (status == 0, "invariant") ; 4877 s = _counter; 4878 _counter = 1; 4879 if (s < 1) { 4880 if (WorkAroundNPTLTimedWaitHang) { 4881 status = pthread_cond_signal (_cond) ; 4882 assert (status == 0, "invariant") ; 4883 status = pthread_mutex_unlock(_mutex); 4884 assert (status == 0, "invariant") ; 4885 } else { 4886 status = pthread_mutex_unlock(_mutex); 4887 assert (status == 0, "invariant") ; 4888 status = pthread_cond_signal (_cond) ; 4889 assert (status == 0, "invariant") ; 4890 } 4891 } else { 4892 pthread_mutex_unlock(_mutex); 4893 assert (status == 0, "invariant") ; 4894 } 4895 } 4896 4897 4898 extern char** environ; 4899 4900 #ifndef __NR_fork 4901 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 4902 #endif 4903 4904 #ifndef __NR_execve 4905 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 4906 #endif 4907 4908 // Run the specified command in a separate process. Return its exit value, 4909 // or -1 on failure (e.g. can't fork a new process). 4910 // Unlike system(), this function can be called from signal handler. It 4911 // doesn't block SIGINT et al. 4912 int os::fork_and_exec(char* cmd) { 4913 const char * argv[4] = {"sh", "-c", cmd, NULL}; 4914 4915 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 4916 // pthread_atfork handlers and reset pthread library. All we need is a 4917 // separate process to execve. Make a direct syscall to fork process. 4918 // On IA64 there's no fork syscall, we have to use fork() and hope for 4919 // the best... 4920 pid_t pid = NOT_IA64(syscall(__NR_fork);) 4921 IA64_ONLY(fork();) 4922 4923 if (pid < 0) { 4924 // fork failed 4925 return -1; 4926 4927 } else if (pid == 0) { 4928 // child process 4929 4930 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 4931 // first to kill every thread on the thread list. Because this list is 4932 // not reset by fork() (see notes above), execve() will instead kill 4933 // every thread in the parent process. We know this is the only thread 4934 // in the new process, so make a system call directly. 4935 // IA64 should use normal execve() from glibc to match the glibc fork() 4936 // above. 4937 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 4938 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 4939 4940 // execve failed 4941 _exit(-1); 4942 4943 } else { 4944 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 4945 // care about the actual exit code, for now. 4946 4947 int status; 4948 4949 // Wait for the child process to exit. This returns immediately if 4950 // the child has already exited. */ 4951 while (waitpid(pid, &status, 0) < 0) { 4952 switch (errno) { 4953 case ECHILD: return 0; 4954 case EINTR: break; 4955 default: return -1; 4956 } 4957 } 4958 4959 if (WIFEXITED(status)) { 4960 // The child exited normally; get its exit code. 4961 return WEXITSTATUS(status); 4962 } else if (WIFSIGNALED(status)) { 4963 // The child exited because of a signal 4964 // The best value to return is 0x80 + signal number, 4965 // because that is what all Unix shells do, and because 4966 // it allows callers to distinguish between process exit and 4967 // process death by signal. 4968 return 0x80 + WTERMSIG(status); 4969 } else { 4970 // Unknown exit code; pass it through 4971 return status; 4972 } 4973 } 4974 }