1 /* 2 * Copyright 1999-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 20 * CA 95054 USA or visit www.sun.com if you need additional information or 21 * have any questions. 22 * 23 */ 24 25 // do not include precompiled header file 26 # include "incls/_os_linux.cpp.incl" 27 28 // put OS-includes here 29 # include <sys/types.h> 30 # include <sys/mman.h> 31 # include <pthread.h> 32 # include <signal.h> 33 # include <errno.h> 34 # include <dlfcn.h> 35 # include <stdio.h> 36 # include <unistd.h> 37 # include <sys/resource.h> 38 # include <pthread.h> 39 # include <sys/stat.h> 40 # include <sys/time.h> 41 # include <sys/times.h> 42 # include <sys/utsname.h> 43 # include <sys/socket.h> 44 # include <sys/wait.h> 45 # include <pwd.h> 46 # include <poll.h> 47 # include <semaphore.h> 48 # include <fcntl.h> 49 # include <string.h> 50 # include <syscall.h> 51 # include <sys/sysinfo.h> 52 # include <gnu/libc-version.h> 53 # include <sys/ipc.h> 54 # include <sys/shm.h> 55 # include <link.h> 56 57 #define MAX_PATH (2 * K) 58 59 // for timer info max values which include all bits 60 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) 61 #define SEC_IN_NANOSECS 1000000000LL 62 63 //////////////////////////////////////////////////////////////////////////////// 64 // global variables 65 julong os::Linux::_physical_memory = 0; 66 67 address os::Linux::_initial_thread_stack_bottom = NULL; 68 uintptr_t os::Linux::_initial_thread_stack_size = 0; 69 70 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; 71 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; 72 Mutex* os::Linux::_createThread_lock = NULL; 73 pthread_t os::Linux::_main_thread; 74 int os::Linux::_page_size = -1; 75 bool os::Linux::_is_floating_stack = false; 76 bool os::Linux::_is_NPTL = false; 77 bool os::Linux::_supports_fast_thread_cpu_time = false; 78 const char * os::Linux::_glibc_version = NULL; 79 const char * os::Linux::_libpthread_version = NULL; 80 81 static jlong initial_time_count=0; 82 83 static int clock_tics_per_sec = 100; 84 85 // For diagnostics to print a message once. see run_periodic_checks 86 static sigset_t check_signal_done; 87 static bool check_signals = true;; 88 89 static pid_t _initial_pid = 0; 90 91 /* Signal number used to suspend/resume a thread */ 92 93 /* do not use any signal number less than SIGSEGV, see 4355769 */ 94 static int SR_signum = SIGUSR2; 95 sigset_t SR_sigset; 96 97 /* Used to protect dlsym() calls */ 98 static pthread_mutex_t dl_mutex; 99 100 //////////////////////////////////////////////////////////////////////////////// 101 // utility functions 102 103 static int SR_initialize(); 104 static int SR_finalize(); 105 106 julong os::available_memory() { 107 return Linux::available_memory(); 108 } 109 110 julong os::Linux::available_memory() { 111 // values in struct sysinfo are "unsigned long" 112 struct sysinfo si; 113 sysinfo(&si); 114 115 return (julong)si.freeram * si.mem_unit; 116 } 117 118 julong os::physical_memory() { 119 return Linux::physical_memory(); 120 } 121 122 julong os::allocatable_physical_memory(julong size) { 123 #ifdef _LP64 124 return size; 125 #else 126 julong result = MIN2(size, (julong)3800*M); 127 if (!is_allocatable(result)) { 128 // See comments under solaris for alignment considerations 129 julong reasonable_size = (julong)2*G - 2 * os::vm_page_size(); 130 result = MIN2(size, reasonable_size); 131 } 132 return result; 133 #endif // _LP64 134 } 135 136 //////////////////////////////////////////////////////////////////////////////// 137 // environment support 138 139 bool os::getenv(const char* name, char* buf, int len) { 140 const char* val = ::getenv(name); 141 if (val != NULL && strlen(val) < (size_t)len) { 142 strcpy(buf, val); 143 return true; 144 } 145 if (len > 0) buf[0] = 0; // return a null string 146 return false; 147 } 148 149 150 // Return true if user is running as root. 151 152 bool os::have_special_privileges() { 153 static bool init = false; 154 static bool privileges = false; 155 if (!init) { 156 privileges = (getuid() != geteuid()) || (getgid() != getegid()); 157 init = true; 158 } 159 return privileges; 160 } 161 162 163 #ifndef SYS_gettid 164 // i386: 224, ia64: 1105, amd64: 186, sparc 143 165 #ifdef __ia64__ 166 #define SYS_gettid 1105 167 #elif __i386__ 168 #define SYS_gettid 224 169 #elif __amd64__ 170 #define SYS_gettid 186 171 #elif __sparc__ 172 #define SYS_gettid 143 173 #else 174 #error define gettid for the arch 175 #endif 176 #endif 177 178 // Cpu architecture string 179 #if defined(ZERO) 180 static char cpu_arch[] = ZERO_LIBARCH; 181 #elif defined(IA64) 182 static char cpu_arch[] = "ia64"; 183 #elif defined(IA32) 184 static char cpu_arch[] = "i386"; 185 #elif defined(AMD64) 186 static char cpu_arch[] = "amd64"; 187 #elif defined(SPARC) 188 # ifdef _LP64 189 static char cpu_arch[] = "sparcv9"; 190 # else 191 static char cpu_arch[] = "sparc"; 192 # endif 193 #else 194 #error Add appropriate cpu_arch setting 195 #endif 196 197 198 // pid_t gettid() 199 // 200 // Returns the kernel thread id of the currently running thread. Kernel 201 // thread id is used to access /proc. 202 // 203 // (Note that getpid() on LinuxThreads returns kernel thread id too; but 204 // on NPTL, it returns the same pid for all threads, as required by POSIX.) 205 // 206 pid_t os::Linux::gettid() { 207 int rslt = syscall(SYS_gettid); 208 if (rslt == -1) { 209 // old kernel, no NPTL support 210 return getpid(); 211 } else { 212 return (pid_t)rslt; 213 } 214 } 215 216 // Most versions of linux have a bug where the number of processors are 217 // determined by looking at the /proc file system. In a chroot environment, 218 // the system call returns 1. This causes the VM to act as if it is 219 // a single processor and elide locking (see is_MP() call). 220 static bool unsafe_chroot_detected = false; 221 static const char *unstable_chroot_error = "/proc file system not found.\n" 222 "Java may be unstable running multithreaded in a chroot " 223 "environment on Linux when /proc filesystem is not mounted."; 224 225 void os::Linux::initialize_system_info() { 226 _processor_count = sysconf(_SC_NPROCESSORS_CONF); 227 if (_processor_count == 1) { 228 pid_t pid = os::Linux::gettid(); 229 char fname[32]; 230 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); 231 FILE *fp = fopen(fname, "r"); 232 if (fp == NULL) { 233 unsafe_chroot_detected = true; 234 } else { 235 fclose(fp); 236 } 237 } 238 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); 239 assert(_processor_count > 0, "linux error"); 240 } 241 242 void os::init_system_properties_values() { 243 // char arch[12]; 244 // sysinfo(SI_ARCHITECTURE, arch, sizeof(arch)); 245 246 // The next steps are taken in the product version: 247 // 248 // Obtain the JAVA_HOME value from the location of libjvm[_g].so. 249 // This library should be located at: 250 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm[_g].so. 251 // 252 // If "/jre/lib/" appears at the right place in the path, then we 253 // assume libjvm[_g].so is installed in a JDK and we use this path. 254 // 255 // Otherwise exit with message: "Could not create the Java virtual machine." 256 // 257 // The following extra steps are taken in the debugging version: 258 // 259 // If "/jre/lib/" does NOT appear at the right place in the path 260 // instead of exit check for $JAVA_HOME environment variable. 261 // 262 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>, 263 // then we append a fake suffix "hotspot/libjvm[_g].so" to this path so 264 // it looks like libjvm[_g].so is installed there 265 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm[_g].so. 266 // 267 // Otherwise exit. 268 // 269 // Important note: if the location of libjvm.so changes this 270 // code needs to be changed accordingly. 271 272 // The next few definitions allow the code to be verbatim: 273 #define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n)) 274 #define getenv(n) ::getenv(n) 275 276 /* 277 * See ld(1): 278 * The linker uses the following search paths to locate required 279 * shared libraries: 280 * 1: ... 281 * ... 282 * 7: The default directories, normally /lib and /usr/lib. 283 */ 284 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) 285 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" 286 #else 287 #define DEFAULT_LIBPATH "/lib:/usr/lib" 288 #endif 289 290 #define EXTENSIONS_DIR "/lib/ext" 291 #define ENDORSED_DIR "/lib/endorsed" 292 #define REG_DIR "/usr/java/packages" 293 294 { 295 /* sysclasspath, java_home, dll_dir */ 296 { 297 char *home_path; 298 char *dll_path; 299 char *pslash; 300 char buf[MAXPATHLEN]; 301 os::jvm_path(buf, sizeof(buf)); 302 303 // Found the full path to libjvm.so. 304 // Now cut the path to <java_home>/jre if we can. 305 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */ 306 pslash = strrchr(buf, '/'); 307 if (pslash != NULL) 308 *pslash = '\0'; /* get rid of /{client|server|hotspot} */ 309 dll_path = malloc(strlen(buf) + 1); 310 if (dll_path == NULL) 311 return; 312 strcpy(dll_path, buf); 313 Arguments::set_dll_dir(dll_path); 314 315 if (pslash != NULL) { 316 pslash = strrchr(buf, '/'); 317 if (pslash != NULL) { 318 *pslash = '\0'; /* get rid of /<arch> */ 319 pslash = strrchr(buf, '/'); 320 if (pslash != NULL) 321 *pslash = '\0'; /* get rid of /lib */ 322 } 323 } 324 325 home_path = malloc(strlen(buf) + 1); 326 if (home_path == NULL) 327 return; 328 strcpy(home_path, buf); 329 Arguments::set_java_home(home_path); 330 331 if (!set_boot_path('/', ':')) 332 return; 333 } 334 335 /* 336 * Where to look for native libraries 337 * 338 * Note: Due to a legacy implementation, most of the library path 339 * is set in the launcher. This was to accomodate linking restrictions 340 * on legacy Linux implementations (which are no longer supported). 341 * Eventually, all the library path setting will be done here. 342 * 343 * However, to prevent the proliferation of improperly built native 344 * libraries, the new path component /usr/java/packages is added here. 345 * Eventually, all the library path setting will be done here. 346 */ 347 { 348 char *ld_library_path; 349 350 /* 351 * Construct the invariant part of ld_library_path. Note that the 352 * space for the colon and the trailing null are provided by the 353 * nulls included by the sizeof operator (so actually we allocate 354 * a byte more than necessary). 355 */ 356 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") + 357 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH)); 358 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch); 359 360 /* 361 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It 362 * should always exist (until the legacy problem cited above is 363 * addressed). 364 */ 365 char *v = getenv("LD_LIBRARY_PATH"); 366 if (v != NULL) { 367 char *t = ld_library_path; 368 /* That's +1 for the colon and +1 for the trailing '\0' */ 369 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1); 370 sprintf(ld_library_path, "%s:%s", v, t); 371 } 372 Arguments::set_library_path(ld_library_path); 373 } 374 375 /* 376 * Extensions directories. 377 * 378 * Note that the space for the colon and the trailing null are provided 379 * by the nulls included by the sizeof operator (so actually one byte more 380 * than necessary is allocated). 381 */ 382 { 383 char *buf = malloc(strlen(Arguments::get_java_home()) + 384 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR)); 385 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR, 386 Arguments::get_java_home()); 387 Arguments::set_ext_dirs(buf); 388 } 389 390 /* Endorsed standards default directory. */ 391 { 392 char * buf; 393 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR)); 394 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); 395 Arguments::set_endorsed_dirs(buf); 396 } 397 } 398 399 #undef malloc 400 #undef getenv 401 #undef EXTENSIONS_DIR 402 #undef ENDORSED_DIR 403 404 // Done 405 return; 406 } 407 408 //////////////////////////////////////////////////////////////////////////////// 409 // breakpoint support 410 411 void os::breakpoint() { 412 BREAKPOINT; 413 } 414 415 extern "C" void breakpoint() { 416 // use debugger to set breakpoint here 417 } 418 419 //////////////////////////////////////////////////////////////////////////////// 420 // signal support 421 422 debug_only(static bool signal_sets_initialized = false); 423 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs; 424 425 bool os::Linux::is_sig_ignored(int sig) { 426 struct sigaction oact; 427 sigaction(sig, (struct sigaction*)NULL, &oact); 428 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction) 429 : CAST_FROM_FN_PTR(void*, oact.sa_handler); 430 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) 431 return true; 432 else 433 return false; 434 } 435 436 void os::Linux::signal_sets_init() { 437 // Should also have an assertion stating we are still single-threaded. 438 assert(!signal_sets_initialized, "Already initialized"); 439 // Fill in signals that are necessarily unblocked for all threads in 440 // the VM. Currently, we unblock the following signals: 441 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden 442 // by -Xrs (=ReduceSignalUsage)); 443 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all 444 // other threads. The "ReduceSignalUsage" boolean tells us not to alter 445 // the dispositions or masks wrt these signals. 446 // Programs embedding the VM that want to use the above signals for their 447 // own purposes must, at this time, use the "-Xrs" option to prevent 448 // interference with shutdown hooks and BREAK_SIGNAL thread dumping. 449 // (See bug 4345157, and other related bugs). 450 // In reality, though, unblocking these signals is really a nop, since 451 // these signals are not blocked by default. 452 sigemptyset(&unblocked_sigs); 453 sigemptyset(&allowdebug_blocked_sigs); 454 sigaddset(&unblocked_sigs, SIGILL); 455 sigaddset(&unblocked_sigs, SIGSEGV); 456 sigaddset(&unblocked_sigs, SIGBUS); 457 sigaddset(&unblocked_sigs, SIGFPE); 458 sigaddset(&unblocked_sigs, SR_signum); 459 460 if (!ReduceSignalUsage) { 461 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { 462 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); 463 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); 464 } 465 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { 466 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); 467 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); 468 } 469 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) { 470 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL); 471 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL); 472 } 473 } 474 // Fill in signals that are blocked by all but the VM thread. 475 sigemptyset(&vm_sigs); 476 if (!ReduceSignalUsage) 477 sigaddset(&vm_sigs, BREAK_SIGNAL); 478 debug_only(signal_sets_initialized = true); 479 480 } 481 482 // These are signals that are unblocked while a thread is running Java. 483 // (For some reason, they get blocked by default.) 484 sigset_t* os::Linux::unblocked_signals() { 485 assert(signal_sets_initialized, "Not initialized"); 486 return &unblocked_sigs; 487 } 488 489 // These are the signals that are blocked while a (non-VM) thread is 490 // running Java. Only the VM thread handles these signals. 491 sigset_t* os::Linux::vm_signals() { 492 assert(signal_sets_initialized, "Not initialized"); 493 return &vm_sigs; 494 } 495 496 // These are signals that are blocked during cond_wait to allow debugger in 497 sigset_t* os::Linux::allowdebug_blocked_signals() { 498 assert(signal_sets_initialized, "Not initialized"); 499 return &allowdebug_blocked_sigs; 500 } 501 502 void os::Linux::hotspot_sigmask(Thread* thread) { 503 504 //Save caller's signal mask before setting VM signal mask 505 sigset_t caller_sigmask; 506 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask); 507 508 OSThread* osthread = thread->osthread(); 509 osthread->set_caller_sigmask(caller_sigmask); 510 511 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL); 512 513 if (!ReduceSignalUsage) { 514 if (thread->is_VM_thread()) { 515 // Only the VM thread handles BREAK_SIGNAL ... 516 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL); 517 } else { 518 // ... all other threads block BREAK_SIGNAL 519 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL); 520 } 521 } 522 } 523 524 ////////////////////////////////////////////////////////////////////////////// 525 // detecting pthread library 526 527 void os::Linux::libpthread_init() { 528 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION 529 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a 530 // generic name for earlier versions. 531 // Define macros here so we can build HotSpot on old systems. 532 # ifndef _CS_GNU_LIBC_VERSION 533 # define _CS_GNU_LIBC_VERSION 2 534 # endif 535 # ifndef _CS_GNU_LIBPTHREAD_VERSION 536 # define _CS_GNU_LIBPTHREAD_VERSION 3 537 # endif 538 539 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); 540 if (n > 0) { 541 char *str = (char *)malloc(n); 542 confstr(_CS_GNU_LIBC_VERSION, str, n); 543 os::Linux::set_glibc_version(str); 544 } else { 545 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() 546 static char _gnu_libc_version[32]; 547 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), 548 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); 549 os::Linux::set_glibc_version(_gnu_libc_version); 550 } 551 552 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); 553 if (n > 0) { 554 char *str = (char *)malloc(n); 555 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); 556 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells 557 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this 558 // is the case. LinuxThreads has a hard limit on max number of threads. 559 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. 560 // On the other hand, NPTL does not have such a limit, sysconf() 561 // will return -1 and errno is not changed. Check if it is really NPTL. 562 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && 563 strstr(str, "NPTL") && 564 sysconf(_SC_THREAD_THREADS_MAX) > 0) { 565 free(str); 566 os::Linux::set_libpthread_version("linuxthreads"); 567 } else { 568 os::Linux::set_libpthread_version(str); 569 } 570 } else { 571 // glibc before 2.3.2 only has LinuxThreads. 572 os::Linux::set_libpthread_version("linuxthreads"); 573 } 574 575 if (strstr(libpthread_version(), "NPTL")) { 576 os::Linux::set_is_NPTL(); 577 } else { 578 os::Linux::set_is_LinuxThreads(); 579 } 580 581 // LinuxThreads have two flavors: floating-stack mode, which allows variable 582 // stack size; and fixed-stack mode. NPTL is always floating-stack. 583 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { 584 os::Linux::set_is_floating_stack(); 585 } 586 } 587 588 ///////////////////////////////////////////////////////////////////////////// 589 // thread stack 590 591 // Force Linux kernel to expand current thread stack. If "bottom" is close 592 // to the stack guard, caller should block all signals. 593 // 594 // MAP_GROWSDOWN: 595 // A special mmap() flag that is used to implement thread stacks. It tells 596 // kernel that the memory region should extend downwards when needed. This 597 // allows early versions of LinuxThreads to only mmap the first few pages 598 // when creating a new thread. Linux kernel will automatically expand thread 599 // stack as needed (on page faults). 600 // 601 // However, because the memory region of a MAP_GROWSDOWN stack can grow on 602 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN 603 // region, it's hard to tell if the fault is due to a legitimate stack 604 // access or because of reading/writing non-exist memory (e.g. buffer 605 // overrun). As a rule, if the fault happens below current stack pointer, 606 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the 607 // application (see Linux kernel fault.c). 608 // 609 // This Linux feature can cause SIGSEGV when VM bangs thread stack for 610 // stack overflow detection. 611 // 612 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do 613 // not use this flag. However, the stack of initial thread is not created 614 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though 615 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack 616 // and then attach the thread to JVM. 617 // 618 // To get around the problem and allow stack banging on Linux, we need to 619 // manually expand thread stack after receiving the SIGSEGV. 620 // 621 // There are two ways to expand thread stack to address "bottom", we used 622 // both of them in JVM before 1.5: 623 // 1. adjust stack pointer first so that it is below "bottom", and then 624 // touch "bottom" 625 // 2. mmap() the page in question 626 // 627 // Now alternate signal stack is gone, it's harder to use 2. For instance, 628 // if current sp is already near the lower end of page 101, and we need to 629 // call mmap() to map page 100, it is possible that part of the mmap() frame 630 // will be placed in page 100. When page 100 is mapped, it is zero-filled. 631 // That will destroy the mmap() frame and cause VM to crash. 632 // 633 // The following code works by adjusting sp first, then accessing the "bottom" 634 // page to force a page fault. Linux kernel will then automatically expand the 635 // stack mapping. 636 // 637 // _expand_stack_to() assumes its frame size is less than page size, which 638 // should always be true if the function is not inlined. 639 640 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute 641 #define NOINLINE 642 #else 643 #define NOINLINE __attribute__ ((noinline)) 644 #endif 645 646 static void _expand_stack_to(address bottom) NOINLINE; 647 648 static void _expand_stack_to(address bottom) { 649 address sp; 650 size_t size; 651 volatile char *p; 652 653 // Adjust bottom to point to the largest address within the same page, it 654 // gives us a one-page buffer if alloca() allocates slightly more memory. 655 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); 656 bottom += os::Linux::page_size() - 1; 657 658 // sp might be slightly above current stack pointer; if that's the case, we 659 // will alloca() a little more space than necessary, which is OK. Don't use 660 // os::current_stack_pointer(), as its result can be slightly below current 661 // stack pointer, causing us to not alloca enough to reach "bottom". 662 sp = (address)&sp; 663 664 if (sp > bottom) { 665 size = sp - bottom; 666 p = (volatile char *)alloca(size); 667 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); 668 p[0] = '\0'; 669 } 670 } 671 672 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { 673 assert(t!=NULL, "just checking"); 674 assert(t->osthread()->expanding_stack(), "expand should be set"); 675 assert(t->stack_base() != NULL, "stack_base was not initialized"); 676 677 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { 678 sigset_t mask_all, old_sigset; 679 sigfillset(&mask_all); 680 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); 681 _expand_stack_to(addr); 682 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); 683 return true; 684 } 685 return false; 686 } 687 688 ////////////////////////////////////////////////////////////////////////////// 689 // create new thread 690 691 static address highest_vm_reserved_address(); 692 693 // check if it's safe to start a new thread 694 static bool _thread_safety_check(Thread* thread) { 695 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { 696 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) 697 // Heap is mmap'ed at lower end of memory space. Thread stacks are 698 // allocated (MAP_FIXED) from high address space. Every thread stack 699 // occupies a fixed size slot (usually 2Mbytes, but user can change 700 // it to other values if they rebuild LinuxThreads). 701 // 702 // Problem with MAP_FIXED is that mmap() can still succeed even part of 703 // the memory region has already been mmap'ed. That means if we have too 704 // many threads and/or very large heap, eventually thread stack will 705 // collide with heap. 706 // 707 // Here we try to prevent heap/stack collision by comparing current 708 // stack bottom with the highest address that has been mmap'ed by JVM 709 // plus a safety margin for memory maps created by native code. 710 // 711 // This feature can be disabled by setting ThreadSafetyMargin to 0 712 // 713 if (ThreadSafetyMargin > 0) { 714 address stack_bottom = os::current_stack_base() - os::current_stack_size(); 715 716 // not safe if our stack extends below the safety margin 717 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); 718 } else { 719 return true; 720 } 721 } else { 722 // Floating stack LinuxThreads or NPTL: 723 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When 724 // there's not enough space left, pthread_create() will fail. If we come 725 // here, that means enough space has been reserved for stack. 726 return true; 727 } 728 } 729 730 // Thread start routine for all newly created threads 731 static void *java_start(Thread *thread) { 732 // Try to randomize the cache line index of hot stack frames. 733 // This helps when threads of the same stack traces evict each other's 734 // cache lines. The threads can be either from the same JVM instance, or 735 // from different JVM instances. The benefit is especially true for 736 // processors with hyperthreading technology. 737 static int counter = 0; 738 int pid = os::current_process_id(); 739 alloca(((pid ^ counter++) & 7) * 128); 740 741 ThreadLocalStorage::set_thread(thread); 742 743 OSThread* osthread = thread->osthread(); 744 Monitor* sync = osthread->startThread_lock(); 745 746 // non floating stack LinuxThreads needs extra check, see above 747 if (!_thread_safety_check(thread)) { 748 // notify parent thread 749 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 750 osthread->set_state(ZOMBIE); 751 sync->notify_all(); 752 return NULL; 753 } 754 755 // thread_id is kernel thread id (similar to Solaris LWP id) 756 osthread->set_thread_id(os::Linux::gettid()); 757 758 if (UseNUMA) { 759 int lgrp_id = os::numa_get_group_id(); 760 if (lgrp_id != -1) { 761 thread->set_lgrp_id(lgrp_id); 762 } 763 } 764 // initialize signal mask for this thread 765 os::Linux::hotspot_sigmask(thread); 766 767 // initialize floating point control register 768 os::Linux::init_thread_fpu_state(); 769 770 // handshaking with parent thread 771 { 772 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag); 773 774 // notify parent thread 775 osthread->set_state(INITIALIZED); 776 sync->notify_all(); 777 778 // wait until os::start_thread() 779 while (osthread->get_state() == INITIALIZED) { 780 sync->wait(Mutex::_no_safepoint_check_flag); 781 } 782 } 783 784 // call one more level start routine 785 thread->run(); 786 787 return 0; 788 } 789 790 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) { 791 assert(thread->osthread() == NULL, "caller responsible"); 792 793 // Allocate the OSThread object 794 OSThread* osthread = new OSThread(NULL, NULL); 795 if (osthread == NULL) { 796 return false; 797 } 798 799 // set the correct thread state 800 osthread->set_thread_type(thr_type); 801 802 // Initial state is ALLOCATED but not INITIALIZED 803 osthread->set_state(ALLOCATED); 804 805 thread->set_osthread(osthread); 806 807 // init thread attributes 808 pthread_attr_t attr; 809 pthread_attr_init(&attr); 810 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 811 812 // stack size 813 if (os::Linux::supports_variable_stack_size()) { 814 // calculate stack size if it's not specified by caller 815 if (stack_size == 0) { 816 stack_size = os::Linux::default_stack_size(thr_type); 817 818 switch (thr_type) { 819 case os::java_thread: 820 // Java threads use ThreadStackSize which default value can be changed with the flag -Xss 821 if (JavaThread::stack_size_at_create() > 0) stack_size = JavaThread::stack_size_at_create(); 822 break; 823 case os::compiler_thread: 824 if (CompilerThreadStackSize > 0) { 825 stack_size = (size_t)(CompilerThreadStackSize * K); 826 break; 827 } // else fall through: 828 // use VMThreadStackSize if CompilerThreadStackSize is not defined 829 case os::vm_thread: 830 case os::pgc_thread: 831 case os::cgc_thread: 832 case os::watcher_thread: 833 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K); 834 break; 835 } 836 } 837 838 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed); 839 pthread_attr_setstacksize(&attr, stack_size); 840 } else { 841 // let pthread_create() pick the default value. 842 } 843 844 // glibc guard page 845 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); 846 847 ThreadState state; 848 849 { 850 // Serialize thread creation if we are running with fixed stack LinuxThreads 851 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); 852 if (lock) { 853 os::Linux::createThread_lock()->lock_without_safepoint_check(); 854 } 855 856 pthread_t tid; 857 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread); 858 859 pthread_attr_destroy(&attr); 860 861 if (ret != 0) { 862 if (PrintMiscellaneous && (Verbose || WizardMode)) { 863 perror("pthread_create()"); 864 } 865 // Need to clean up stuff we've allocated so far 866 thread->set_osthread(NULL); 867 delete osthread; 868 if (lock) os::Linux::createThread_lock()->unlock(); 869 return false; 870 } 871 872 // Store pthread info into the OSThread 873 osthread->set_pthread_id(tid); 874 875 // Wait until child thread is either initialized or aborted 876 { 877 Monitor* sync_with_child = osthread->startThread_lock(); 878 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 879 while ((state = osthread->get_state()) == ALLOCATED) { 880 sync_with_child->wait(Mutex::_no_safepoint_check_flag); 881 } 882 } 883 884 if (lock) { 885 os::Linux::createThread_lock()->unlock(); 886 } 887 } 888 889 // Aborted due to thread limit being reached 890 if (state == ZOMBIE) { 891 thread->set_osthread(NULL); 892 delete osthread; 893 return false; 894 } 895 896 // The thread is returned suspended (in state INITIALIZED), 897 // and is started higher up in the call chain 898 assert(state == INITIALIZED, "race condition"); 899 return true; 900 } 901 902 ///////////////////////////////////////////////////////////////////////////// 903 // attach existing thread 904 905 // bootstrap the main thread 906 bool os::create_main_thread(JavaThread* thread) { 907 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread"); 908 return create_attached_thread(thread); 909 } 910 911 bool os::create_attached_thread(JavaThread* thread) { 912 #ifdef ASSERT 913 thread->verify_not_published(); 914 #endif 915 916 // Allocate the OSThread object 917 OSThread* osthread = new OSThread(NULL, NULL); 918 919 if (osthread == NULL) { 920 return false; 921 } 922 923 // Store pthread info into the OSThread 924 osthread->set_thread_id(os::Linux::gettid()); 925 osthread->set_pthread_id(::pthread_self()); 926 927 // initialize floating point control register 928 os::Linux::init_thread_fpu_state(); 929 930 // Initial thread state is RUNNABLE 931 osthread->set_state(RUNNABLE); 932 933 thread->set_osthread(osthread); 934 935 if (UseNUMA) { 936 int lgrp_id = os::numa_get_group_id(); 937 if (lgrp_id != -1) { 938 thread->set_lgrp_id(lgrp_id); 939 } 940 } 941 942 if (os::Linux::is_initial_thread()) { 943 // If current thread is initial thread, its stack is mapped on demand, 944 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map 945 // the entire stack region to avoid SEGV in stack banging. 946 // It is also useful to get around the heap-stack-gap problem on SuSE 947 // kernel (see 4821821 for details). We first expand stack to the top 948 // of yellow zone, then enable stack yellow zone (order is significant, 949 // enabling yellow zone first will crash JVM on SuSE Linux), so there 950 // is no gap between the last two virtual memory regions. 951 952 JavaThread *jt = (JavaThread *)thread; 953 address addr = jt->stack_yellow_zone_base(); 954 assert(addr != NULL, "initialization problem?"); 955 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); 956 957 osthread->set_expanding_stack(); 958 os::Linux::manually_expand_stack(jt, addr); 959 osthread->clear_expanding_stack(); 960 } 961 962 // initialize signal mask for this thread 963 // and save the caller's signal mask 964 os::Linux::hotspot_sigmask(thread); 965 966 return true; 967 } 968 969 void os::pd_start_thread(Thread* thread) { 970 OSThread * osthread = thread->osthread(); 971 assert(osthread->get_state() != INITIALIZED, "just checking"); 972 Monitor* sync_with_child = osthread->startThread_lock(); 973 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag); 974 sync_with_child->notify(); 975 } 976 977 // Free Linux resources related to the OSThread 978 void os::free_thread(OSThread* osthread) { 979 assert(osthread != NULL, "osthread not set"); 980 981 if (Thread::current()->osthread() == osthread) { 982 // Restore caller's signal mask 983 sigset_t sigmask = osthread->caller_sigmask(); 984 pthread_sigmask(SIG_SETMASK, &sigmask, NULL); 985 } 986 987 delete osthread; 988 } 989 990 ////////////////////////////////////////////////////////////////////////////// 991 // thread local storage 992 993 int os::allocate_thread_local_storage() { 994 pthread_key_t key; 995 int rslt = pthread_key_create(&key, NULL); 996 assert(rslt == 0, "cannot allocate thread local storage"); 997 return (int)key; 998 } 999 1000 // Note: This is currently not used by VM, as we don't destroy TLS key 1001 // on VM exit. 1002 void os::free_thread_local_storage(int index) { 1003 int rslt = pthread_key_delete((pthread_key_t)index); 1004 assert(rslt == 0, "invalid index"); 1005 } 1006 1007 void os::thread_local_storage_at_put(int index, void* value) { 1008 int rslt = pthread_setspecific((pthread_key_t)index, value); 1009 assert(rslt == 0, "pthread_setspecific failed"); 1010 } 1011 1012 extern "C" Thread* get_thread() { 1013 return ThreadLocalStorage::thread(); 1014 } 1015 1016 ////////////////////////////////////////////////////////////////////////////// 1017 // initial thread 1018 1019 // Check if current thread is the initial thread, similar to Solaris thr_main. 1020 bool os::Linux::is_initial_thread(void) { 1021 char dummy; 1022 // If called before init complete, thread stack bottom will be null. 1023 // Can be called if fatal error occurs before initialization. 1024 if (initial_thread_stack_bottom() == NULL) return false; 1025 assert(initial_thread_stack_bottom() != NULL && 1026 initial_thread_stack_size() != 0, 1027 "os::init did not locate initial thread's stack region"); 1028 if ((address)&dummy >= initial_thread_stack_bottom() && 1029 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) 1030 return true; 1031 else return false; 1032 } 1033 1034 // Find the virtual memory area that contains addr 1035 static bool find_vma(address addr, address* vma_low, address* vma_high) { 1036 FILE *fp = fopen("/proc/self/maps", "r"); 1037 if (fp) { 1038 address low, high; 1039 while (!feof(fp)) { 1040 if (fscanf(fp, "%p-%p", &low, &high) == 2) { 1041 if (low <= addr && addr < high) { 1042 if (vma_low) *vma_low = low; 1043 if (vma_high) *vma_high = high; 1044 fclose (fp); 1045 return true; 1046 } 1047 } 1048 for (;;) { 1049 int ch = fgetc(fp); 1050 if (ch == EOF || ch == (int)'\n') break; 1051 } 1052 } 1053 fclose(fp); 1054 } 1055 return false; 1056 } 1057 1058 // Locate initial thread stack. This special handling of initial thread stack 1059 // is needed because pthread_getattr_np() on most (all?) Linux distros returns 1060 // bogus value for initial thread. 1061 void os::Linux::capture_initial_stack(size_t max_size) { 1062 // stack size is the easy part, get it from RLIMIT_STACK 1063 size_t stack_size; 1064 struct rlimit rlim; 1065 getrlimit(RLIMIT_STACK, &rlim); 1066 stack_size = rlim.rlim_cur; 1067 1068 // 6308388: a bug in ld.so will relocate its own .data section to the 1069 // lower end of primordial stack; reduce ulimit -s value a little bit 1070 // so we won't install guard page on ld.so's data section. 1071 stack_size -= 2 * page_size(); 1072 1073 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat 1074 // 7.1, in both cases we will get 2G in return value. 1075 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, 1076 // SuSE 7.2, Debian) can not handle alternate signal stack correctly 1077 // for initial thread if its stack size exceeds 6M. Cap it at 2M, 1078 // in case other parts in glibc still assumes 2M max stack size. 1079 // FIXME: alt signal stack is gone, maybe we can relax this constraint? 1080 #ifndef IA64 1081 if (stack_size > 2 * K * K) stack_size = 2 * K * K; 1082 #else 1083 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small 1084 if (stack_size > 4 * K * K) stack_size = 4 * K * K; 1085 #endif 1086 1087 // Try to figure out where the stack base (top) is. This is harder. 1088 // 1089 // When an application is started, glibc saves the initial stack pointer in 1090 // a global variable "__libc_stack_end", which is then used by system 1091 // libraries. __libc_stack_end should be pretty close to stack top. The 1092 // variable is available since the very early days. However, because it is 1093 // a private interface, it could disappear in the future. 1094 // 1095 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar 1096 // to __libc_stack_end, it is very close to stack top, but isn't the real 1097 // stack top. Note that /proc may not exist if VM is running as a chroot 1098 // program, so reading /proc/<pid>/stat could fail. Also the contents of 1099 // /proc/<pid>/stat could change in the future (though unlikely). 1100 // 1101 // We try __libc_stack_end first. If that doesn't work, look for 1102 // /proc/<pid>/stat. If neither of them works, we use current stack pointer 1103 // as a hint, which should work well in most cases. 1104 1105 uintptr_t stack_start; 1106 1107 // try __libc_stack_end first 1108 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); 1109 if (p && *p) { 1110 stack_start = *p; 1111 } else { 1112 // see if we can get the start_stack field from /proc/self/stat 1113 FILE *fp; 1114 int pid; 1115 char state; 1116 int ppid; 1117 int pgrp; 1118 int session; 1119 int nr; 1120 int tpgrp; 1121 unsigned long flags; 1122 unsigned long minflt; 1123 unsigned long cminflt; 1124 unsigned long majflt; 1125 unsigned long cmajflt; 1126 unsigned long utime; 1127 unsigned long stime; 1128 long cutime; 1129 long cstime; 1130 long prio; 1131 long nice; 1132 long junk; 1133 long it_real; 1134 uintptr_t start; 1135 uintptr_t vsize; 1136 uintptr_t rss; 1137 unsigned long rsslim; 1138 uintptr_t scodes; 1139 uintptr_t ecode; 1140 int i; 1141 1142 // Figure what the primordial thread stack base is. Code is inspired 1143 // by email from Hans Boehm. /proc/self/stat begins with current pid, 1144 // followed by command name surrounded by parentheses, state, etc. 1145 char stat[2048]; 1146 int statlen; 1147 1148 fp = fopen("/proc/self/stat", "r"); 1149 if (fp) { 1150 statlen = fread(stat, 1, 2047, fp); 1151 stat[statlen] = '\0'; 1152 fclose(fp); 1153 1154 // Skip pid and the command string. Note that we could be dealing with 1155 // weird command names, e.g. user could decide to rename java launcher 1156 // to "java 1.4.2 :)", then the stat file would look like 1157 // 1234 (java 1.4.2 :)) R ... ... 1158 // We don't really need to know the command string, just find the last 1159 // occurrence of ")" and then start parsing from there. See bug 4726580. 1160 char * s = strrchr(stat, ')'); 1161 1162 i = 0; 1163 if (s) { 1164 // Skip blank chars 1165 do s++; while (isspace(*s)); 1166 1167 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ 1168 /* 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 */ 1169 i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld " 1170 UINTX_FORMAT UINTX_FORMAT UINTX_FORMAT 1171 " %lu " 1172 UINTX_FORMAT UINTX_FORMAT UINTX_FORMAT, 1173 &state, /* 3 %c */ 1174 &ppid, /* 4 %d */ 1175 &pgrp, /* 5 %d */ 1176 &session, /* 6 %d */ 1177 &nr, /* 7 %d */ 1178 &tpgrp, /* 8 %d */ 1179 &flags, /* 9 %lu */ 1180 &minflt, /* 10 %lu */ 1181 &cminflt, /* 11 %lu */ 1182 &majflt, /* 12 %lu */ 1183 &cmajflt, /* 13 %lu */ 1184 &utime, /* 14 %lu */ 1185 &stime, /* 15 %lu */ 1186 &cutime, /* 16 %ld */ 1187 &cstime, /* 17 %ld */ 1188 &prio, /* 18 %ld */ 1189 &nice, /* 19 %ld */ 1190 &junk, /* 20 %ld */ 1191 &it_real, /* 21 %ld */ 1192 &start, /* 22 UINTX_FORMAT */ 1193 &vsize, /* 23 UINTX_FORMAT */ 1194 &rss, /* 24 UINTX_FORMAT */ 1195 &rsslim, /* 25 %lu */ 1196 &scodes, /* 26 UINTX_FORMAT */ 1197 &ecode, /* 27 UINTX_FORMAT */ 1198 &stack_start); /* 28 UINTX_FORMAT */ 1199 } 1200 1201 if (i != 28 - 2) { 1202 assert(false, "Bad conversion from /proc/self/stat"); 1203 // product mode - assume we are the initial thread, good luck in the 1204 // embedded case. 1205 warning("Can't detect initial thread stack location - bad conversion"); 1206 stack_start = (uintptr_t) &rlim; 1207 } 1208 } else { 1209 // For some reason we can't open /proc/self/stat (for example, running on 1210 // FreeBSD with a Linux emulator, or inside chroot), this should work for 1211 // most cases, so don't abort: 1212 warning("Can't detect initial thread stack location - no /proc/self/stat"); 1213 stack_start = (uintptr_t) &rlim; 1214 } 1215 } 1216 1217 // Now we have a pointer (stack_start) very close to the stack top, the 1218 // next thing to do is to figure out the exact location of stack top. We 1219 // can find out the virtual memory area that contains stack_start by 1220 // reading /proc/self/maps, it should be the last vma in /proc/self/maps, 1221 // and its upper limit is the real stack top. (again, this would fail if 1222 // running inside chroot, because /proc may not exist.) 1223 1224 uintptr_t stack_top; 1225 address low, high; 1226 if (find_vma((address)stack_start, &low, &high)) { 1227 // success, "high" is the true stack top. (ignore "low", because initial 1228 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) 1229 stack_top = (uintptr_t)high; 1230 } else { 1231 // failed, likely because /proc/self/maps does not exist 1232 warning("Can't detect initial thread stack location - find_vma failed"); 1233 // best effort: stack_start is normally within a few pages below the real 1234 // stack top, use it as stack top, and reduce stack size so we won't put 1235 // guard page outside stack. 1236 stack_top = stack_start; 1237 stack_size -= 16 * page_size(); 1238 } 1239 1240 // stack_top could be partially down the page so align it 1241 stack_top = align_size_up(stack_top, page_size()); 1242 1243 if (max_size && stack_size > max_size) { 1244 _initial_thread_stack_size = max_size; 1245 } else { 1246 _initial_thread_stack_size = stack_size; 1247 } 1248 1249 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); 1250 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; 1251 } 1252 1253 //////////////////////////////////////////////////////////////////////////////// 1254 // time support 1255 1256 // Time since start-up in seconds to a fine granularity. 1257 // Used by VMSelfDestructTimer and the MemProfiler. 1258 double os::elapsedTime() { 1259 1260 return (double)(os::elapsed_counter()) * 0.000001; 1261 } 1262 1263 jlong os::elapsed_counter() { 1264 timeval time; 1265 int status = gettimeofday(&time, NULL); 1266 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count; 1267 } 1268 1269 jlong os::elapsed_frequency() { 1270 return (1000 * 1000); 1271 } 1272 1273 // For now, we say that linux does not support vtime. I have no idea 1274 // whether it can actually be made to (DLD, 9/13/05). 1275 1276 bool os::supports_vtime() { return false; } 1277 bool os::enable_vtime() { return false; } 1278 bool os::vtime_enabled() { return false; } 1279 double os::elapsedVTime() { 1280 // better than nothing, but not much 1281 return elapsedTime(); 1282 } 1283 1284 jlong os::javaTimeMillis() { 1285 timeval time; 1286 int status = gettimeofday(&time, NULL); 1287 assert(status != -1, "linux error"); 1288 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); 1289 } 1290 1291 #ifndef CLOCK_MONOTONIC 1292 #define CLOCK_MONOTONIC (1) 1293 #endif 1294 1295 void os::Linux::clock_init() { 1296 // we do dlopen's in this particular order due to bug in linux 1297 // dynamical loader (see 6348968) leading to crash on exit 1298 void* handle = dlopen("librt.so.1", RTLD_LAZY); 1299 if (handle == NULL) { 1300 handle = dlopen("librt.so", RTLD_LAZY); 1301 } 1302 1303 if (handle) { 1304 int (*clock_getres_func)(clockid_t, struct timespec*) = 1305 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); 1306 int (*clock_gettime_func)(clockid_t, struct timespec*) = 1307 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); 1308 if (clock_getres_func && clock_gettime_func) { 1309 // See if monotonic clock is supported by the kernel. Note that some 1310 // early implementations simply return kernel jiffies (updated every 1311 // 1/100 or 1/1000 second). It would be bad to use such a low res clock 1312 // for nano time (though the monotonic property is still nice to have). 1313 // It's fixed in newer kernels, however clock_getres() still returns 1314 // 1/HZ. We check if clock_getres() works, but will ignore its reported 1315 // resolution for now. Hopefully as people move to new kernels, this 1316 // won't be a problem. 1317 struct timespec res; 1318 struct timespec tp; 1319 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && 1320 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { 1321 // yes, monotonic clock is supported 1322 _clock_gettime = clock_gettime_func; 1323 } else { 1324 // close librt if there is no monotonic clock 1325 dlclose(handle); 1326 } 1327 } 1328 } 1329 } 1330 1331 #ifndef SYS_clock_getres 1332 1333 #if defined(IA32) || defined(AMD64) 1334 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) 1335 #else 1336 #error Value of SYS_clock_getres not known on this platform 1337 #endif 1338 1339 #endif 1340 1341 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) 1342 1343 void os::Linux::fast_thread_clock_init() { 1344 if (!UseLinuxPosixThreadCPUClocks) { 1345 return; 1346 } 1347 clockid_t clockid; 1348 struct timespec tp; 1349 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = 1350 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); 1351 1352 // Switch to using fast clocks for thread cpu time if 1353 // the sys_clock_getres() returns 0 error code. 1354 // Note, that some kernels may support the current thread 1355 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks 1356 // returned by the pthread_getcpuclockid(). 1357 // If the fast Posix clocks are supported then the sys_clock_getres() 1358 // must return at least tp.tv_sec == 0 which means a resolution 1359 // better than 1 sec. This is extra check for reliability. 1360 1361 if(pthread_getcpuclockid_func && 1362 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && 1363 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { 1364 1365 _supports_fast_thread_cpu_time = true; 1366 _pthread_getcpuclockid = pthread_getcpuclockid_func; 1367 } 1368 } 1369 1370 jlong os::javaTimeNanos() { 1371 if (Linux::supports_monotonic_clock()) { 1372 struct timespec tp; 1373 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp); 1374 assert(status == 0, "gettime error"); 1375 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec); 1376 return result; 1377 } else { 1378 timeval time; 1379 int status = gettimeofday(&time, NULL); 1380 assert(status != -1, "linux error"); 1381 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); 1382 return 1000 * usecs; 1383 } 1384 } 1385 1386 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { 1387 if (Linux::supports_monotonic_clock()) { 1388 info_ptr->max_value = ALL_64_BITS; 1389 1390 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past 1391 info_ptr->may_skip_backward = false; // not subject to resetting or drifting 1392 info_ptr->may_skip_forward = false; // not subject to resetting or drifting 1393 } else { 1394 // gettimeofday - based on time in seconds since the Epoch thus does not wrap 1395 info_ptr->max_value = ALL_64_BITS; 1396 1397 // gettimeofday is a real time clock so it skips 1398 info_ptr->may_skip_backward = true; 1399 info_ptr->may_skip_forward = true; 1400 } 1401 1402 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time 1403 } 1404 1405 // Return the real, user, and system times in seconds from an 1406 // arbitrary fixed point in the past. 1407 bool os::getTimesSecs(double* process_real_time, 1408 double* process_user_time, 1409 double* process_system_time) { 1410 struct tms ticks; 1411 clock_t real_ticks = times(&ticks); 1412 1413 if (real_ticks == (clock_t) (-1)) { 1414 return false; 1415 } else { 1416 double ticks_per_second = (double) clock_tics_per_sec; 1417 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; 1418 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; 1419 *process_real_time = ((double) real_ticks) / ticks_per_second; 1420 1421 return true; 1422 } 1423 } 1424 1425 1426 char * os::local_time_string(char *buf, size_t buflen) { 1427 struct tm t; 1428 time_t long_time; 1429 time(&long_time); 1430 localtime_r(&long_time, &t); 1431 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", 1432 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, 1433 t.tm_hour, t.tm_min, t.tm_sec); 1434 return buf; 1435 } 1436 1437 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { 1438 return localtime_r(clock, res); 1439 } 1440 1441 //////////////////////////////////////////////////////////////////////////////// 1442 // runtime exit support 1443 1444 // Note: os::shutdown() might be called very early during initialization, or 1445 // called from signal handler. Before adding something to os::shutdown(), make 1446 // sure it is async-safe and can handle partially initialized VM. 1447 void os::shutdown() { 1448 1449 // allow PerfMemory to attempt cleanup of any persistent resources 1450 perfMemory_exit(); 1451 1452 // needs to remove object in file system 1453 AttachListener::abort(); 1454 1455 // flush buffered output, finish log files 1456 ostream_abort(); 1457 1458 // Check for abort hook 1459 abort_hook_t abort_hook = Arguments::abort_hook(); 1460 if (abort_hook != NULL) { 1461 abort_hook(); 1462 } 1463 1464 } 1465 1466 // Note: os::abort() might be called very early during initialization, or 1467 // called from signal handler. Before adding something to os::abort(), make 1468 // sure it is async-safe and can handle partially initialized VM. 1469 void os::abort(bool dump_core) { 1470 os::shutdown(); 1471 if (dump_core) { 1472 #ifndef PRODUCT 1473 fdStream out(defaultStream::output_fd()); 1474 out.print_raw("Current thread is "); 1475 char buf[16]; 1476 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id()); 1477 out.print_raw_cr(buf); 1478 out.print_raw_cr("Dumping core ..."); 1479 #endif 1480 ::abort(); // dump core 1481 } 1482 1483 ::exit(1); 1484 } 1485 1486 // Die immediately, no exit hook, no abort hook, no cleanup. 1487 void os::die() { 1488 // _exit() on LinuxThreads only kills current thread 1489 ::abort(); 1490 } 1491 1492 // unused on linux for now. 1493 void os::set_error_file(const char *logfile) {} 1494 1495 intx os::current_thread_id() { return (intx)pthread_self(); } 1496 int os::current_process_id() { 1497 1498 // Under the old linux thread library, linux gives each thread 1499 // its own process id. Because of this each thread will return 1500 // a different pid if this method were to return the result 1501 // of getpid(2). Linux provides no api that returns the pid 1502 // of the launcher thread for the vm. This implementation 1503 // returns a unique pid, the pid of the launcher thread 1504 // that starts the vm 'process'. 1505 1506 // Under the NPTL, getpid() returns the same pid as the 1507 // launcher thread rather than a unique pid per thread. 1508 // Use gettid() if you want the old pre NPTL behaviour. 1509 1510 // if you are looking for the result of a call to getpid() that 1511 // returns a unique pid for the calling thread, then look at the 1512 // OSThread::thread_id() method in osThread_linux.hpp file 1513 1514 return (int)(_initial_pid ? _initial_pid : getpid()); 1515 } 1516 1517 // DLL functions 1518 1519 const char* os::dll_file_extension() { return ".so"; } 1520 1521 const char* os::get_temp_directory() { return "/tmp/"; } 1522 1523 static bool file_exists(const char* filename) { 1524 struct stat statbuf; 1525 if (filename == NULL || strlen(filename) == 0) { 1526 return false; 1527 } 1528 return os::stat(filename, &statbuf) == 0; 1529 } 1530 1531 void os::dll_build_name(char* buffer, size_t buflen, 1532 const char* pname, const char* fname) { 1533 // Copied from libhpi 1534 const size_t pnamelen = pname ? strlen(pname) : 0; 1535 1536 // Quietly truncate on buffer overflow. Should be an error. 1537 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { 1538 *buffer = '\0'; 1539 return; 1540 } 1541 1542 if (pnamelen == 0) { 1543 snprintf(buffer, buflen, "lib%s.so", fname); 1544 } else if (strchr(pname, *os::path_separator()) != NULL) { 1545 int n; 1546 char** pelements = split_path(pname, &n); 1547 for (int i = 0 ; i < n ; i++) { 1548 // Really shouldn't be NULL, but check can't hurt 1549 if (pelements[i] == NULL || strlen(pelements[i]) == 0) { 1550 continue; // skip the empty path values 1551 } 1552 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname); 1553 if (file_exists(buffer)) { 1554 break; 1555 } 1556 } 1557 // release the storage 1558 for (int i = 0 ; i < n ; i++) { 1559 if (pelements[i] != NULL) { 1560 FREE_C_HEAP_ARRAY(char, pelements[i]); 1561 } 1562 } 1563 if (pelements != NULL) { 1564 FREE_C_HEAP_ARRAY(char*, pelements); 1565 } 1566 } else { 1567 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); 1568 } 1569 } 1570 1571 const char* os::get_current_directory(char *buf, int buflen) { 1572 return getcwd(buf, buflen); 1573 } 1574 1575 // check if addr is inside libjvm[_g].so 1576 bool os::address_is_in_vm(address addr) { 1577 static address libjvm_base_addr; 1578 Dl_info dlinfo; 1579 1580 if (libjvm_base_addr == NULL) { 1581 dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo); 1582 libjvm_base_addr = (address)dlinfo.dli_fbase; 1583 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); 1584 } 1585 1586 if (dladdr((void *)addr, &dlinfo)) { 1587 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; 1588 } 1589 1590 return false; 1591 } 1592 1593 bool os::dll_address_to_function_name(address addr, char *buf, 1594 int buflen, int *offset) { 1595 Dl_info dlinfo; 1596 1597 if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) { 1598 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); 1599 if (offset) *offset = addr - (address)dlinfo.dli_saddr; 1600 return true; 1601 } else { 1602 if (buf) buf[0] = '\0'; 1603 if (offset) *offset = -1; 1604 return false; 1605 } 1606 } 1607 1608 struct _address_to_library_name { 1609 address addr; // input : memory address 1610 size_t buflen; // size of fname 1611 char* fname; // output: library name 1612 address base; // library base addr 1613 }; 1614 1615 static int address_to_library_name_callback(struct dl_phdr_info *info, 1616 size_t size, void *data) { 1617 int i; 1618 bool found = false; 1619 address libbase = NULL; 1620 struct _address_to_library_name * d = (struct _address_to_library_name *)data; 1621 1622 // iterate through all loadable segments 1623 for (i = 0; i < info->dlpi_phnum; i++) { 1624 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); 1625 if (info->dlpi_phdr[i].p_type == PT_LOAD) { 1626 // base address of a library is the lowest address of its loaded 1627 // segments. 1628 if (libbase == NULL || libbase > segbase) { 1629 libbase = segbase; 1630 } 1631 // see if 'addr' is within current segment 1632 if (segbase <= d->addr && 1633 d->addr < segbase + info->dlpi_phdr[i].p_memsz) { 1634 found = true; 1635 } 1636 } 1637 } 1638 1639 // dlpi_name is NULL or empty if the ELF file is executable, return 0 1640 // so dll_address_to_library_name() can fall through to use dladdr() which 1641 // can figure out executable name from argv[0]. 1642 if (found && info->dlpi_name && info->dlpi_name[0]) { 1643 d->base = libbase; 1644 if (d->fname) { 1645 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); 1646 } 1647 return 1; 1648 } 1649 return 0; 1650 } 1651 1652 bool os::dll_address_to_library_name(address addr, char* buf, 1653 int buflen, int* offset) { 1654 Dl_info dlinfo; 1655 struct _address_to_library_name data; 1656 1657 // There is a bug in old glibc dladdr() implementation that it could resolve 1658 // to wrong library name if the .so file has a base address != NULL. Here 1659 // we iterate through the program headers of all loaded libraries to find 1660 // out which library 'addr' really belongs to. This workaround can be 1661 // removed once the minimum requirement for glibc is moved to 2.3.x. 1662 data.addr = addr; 1663 data.fname = buf; 1664 data.buflen = buflen; 1665 data.base = NULL; 1666 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); 1667 1668 if (rslt) { 1669 // buf already contains library name 1670 if (offset) *offset = addr - data.base; 1671 return true; 1672 } else if (dladdr((void*)addr, &dlinfo)){ 1673 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); 1674 if (offset) *offset = addr - (address)dlinfo.dli_fbase; 1675 return true; 1676 } else { 1677 if (buf) buf[0] = '\0'; 1678 if (offset) *offset = -1; 1679 return false; 1680 } 1681 } 1682 1683 // Loads .dll/.so and 1684 // in case of error it checks if .dll/.so was built for the 1685 // same architecture as Hotspot is running on 1686 1687 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) 1688 { 1689 void * result= ::dlopen(filename, RTLD_LAZY); 1690 if (result != NULL) { 1691 // Successful loading 1692 return result; 1693 } 1694 1695 Elf32_Ehdr elf_head; 1696 1697 // Read system error message into ebuf 1698 // It may or may not be overwritten below 1699 ::strncpy(ebuf, ::dlerror(), ebuflen-1); 1700 ebuf[ebuflen-1]='\0'; 1701 int diag_msg_max_length=ebuflen-strlen(ebuf); 1702 char* diag_msg_buf=ebuf+strlen(ebuf); 1703 1704 if (diag_msg_max_length==0) { 1705 // No more space in ebuf for additional diagnostics message 1706 return NULL; 1707 } 1708 1709 1710 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK); 1711 1712 if (file_descriptor < 0) { 1713 // Can't open library, report dlerror() message 1714 return NULL; 1715 } 1716 1717 bool failed_to_read_elf_head= 1718 (sizeof(elf_head)!= 1719 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ; 1720 1721 ::close(file_descriptor); 1722 if (failed_to_read_elf_head) { 1723 // file i/o error - report dlerror() msg 1724 return NULL; 1725 } 1726 1727 typedef struct { 1728 Elf32_Half code; // Actual value as defined in elf.h 1729 Elf32_Half compat_class; // Compatibility of archs at VM's sense 1730 char elf_class; // 32 or 64 bit 1731 char endianess; // MSB or LSB 1732 char* name; // String representation 1733 } arch_t; 1734 1735 #ifndef EM_486 1736 #define EM_486 6 /* Intel 80486 */ 1737 #endif 1738 1739 static const arch_t arch_array[]={ 1740 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1741 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"}, 1742 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"}, 1743 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"}, 1744 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1745 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"}, 1746 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"}, 1747 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"}, 1748 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}, 1749 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"}, 1750 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"}, 1751 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"}, 1752 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"}, 1753 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"}, 1754 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"}, 1755 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"} 1756 }; 1757 1758 #if (defined IA32) 1759 static Elf32_Half running_arch_code=EM_386; 1760 #elif (defined AMD64) 1761 static Elf32_Half running_arch_code=EM_X86_64; 1762 #elif (defined IA64) 1763 static Elf32_Half running_arch_code=EM_IA_64; 1764 #elif (defined __sparc) && (defined _LP64) 1765 static Elf32_Half running_arch_code=EM_SPARCV9; 1766 #elif (defined __sparc) && (!defined _LP64) 1767 static Elf32_Half running_arch_code=EM_SPARC; 1768 #elif (defined __powerpc64__) 1769 static Elf32_Half running_arch_code=EM_PPC64; 1770 #elif (defined __powerpc__) 1771 static Elf32_Half running_arch_code=EM_PPC; 1772 #elif (defined ARM) 1773 static Elf32_Half running_arch_code=EM_ARM; 1774 #elif (defined S390) 1775 static Elf32_Half running_arch_code=EM_S390; 1776 #elif (defined ALPHA) 1777 static Elf32_Half running_arch_code=EM_ALPHA; 1778 #elif (defined MIPSEL) 1779 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE; 1780 #elif (defined PARISC) 1781 static Elf32_Half running_arch_code=EM_PARISC; 1782 #elif (defined MIPS) 1783 static Elf32_Half running_arch_code=EM_MIPS; 1784 #elif (defined M68K) 1785 static Elf32_Half running_arch_code=EM_68K; 1786 #else 1787 #error Method os::dll_load requires that one of following is defined:\ 1788 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K 1789 #endif 1790 1791 // Identify compatability class for VM's architecture and library's architecture 1792 // Obtain string descriptions for architectures 1793 1794 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL}; 1795 int running_arch_index=-1; 1796 1797 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) { 1798 if (running_arch_code == arch_array[i].code) { 1799 running_arch_index = i; 1800 } 1801 if (lib_arch.code == arch_array[i].code) { 1802 lib_arch.compat_class = arch_array[i].compat_class; 1803 lib_arch.name = arch_array[i].name; 1804 } 1805 } 1806 1807 assert(running_arch_index != -1, 1808 "Didn't find running architecture code (running_arch_code) in arch_array"); 1809 if (running_arch_index == -1) { 1810 // Even though running architecture detection failed 1811 // we may still continue with reporting dlerror() message 1812 return NULL; 1813 } 1814 1815 if (lib_arch.endianess != arch_array[running_arch_index].endianess) { 1816 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)"); 1817 return NULL; 1818 } 1819 1820 #ifndef S390 1821 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) { 1822 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)"); 1823 return NULL; 1824 } 1825 #endif // !S390 1826 1827 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) { 1828 if ( lib_arch.name!=NULL ) { 1829 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1830 " (Possible cause: can't load %s-bit .so on a %s-bit platform)", 1831 lib_arch.name, arch_array[running_arch_index].name); 1832 } else { 1833 ::snprintf(diag_msg_buf, diag_msg_max_length-1, 1834 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)", 1835 lib_arch.code, 1836 arch_array[running_arch_index].name); 1837 } 1838 } 1839 1840 return NULL; 1841 } 1842 1843 /* 1844 * glibc-2.0 libdl is not MT safe. If you are building with any glibc, 1845 * chances are you might want to run the generated bits against glibc-2.0 1846 * libdl.so, so always use locking for any version of glibc. 1847 */ 1848 void* os::dll_lookup(void* handle, const char* name) { 1849 pthread_mutex_lock(&dl_mutex); 1850 void* res = dlsym(handle, name); 1851 pthread_mutex_unlock(&dl_mutex); 1852 return res; 1853 } 1854 1855 1856 bool _print_ascii_file(const char* filename, outputStream* st) { 1857 int fd = open(filename, O_RDONLY); 1858 if (fd == -1) { 1859 return false; 1860 } 1861 1862 char buf[32]; 1863 int bytes; 1864 while ((bytes = read(fd, buf, sizeof(buf))) > 0) { 1865 st->print_raw(buf, bytes); 1866 } 1867 1868 close(fd); 1869 1870 return true; 1871 } 1872 1873 void os::print_dll_info(outputStream *st) { 1874 st->print_cr("Dynamic libraries:"); 1875 1876 char fname[32]; 1877 pid_t pid = os::Linux::gettid(); 1878 1879 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); 1880 1881 if (!_print_ascii_file(fname, st)) { 1882 st->print("Can not get library information for pid = %d\n", pid); 1883 } 1884 } 1885 1886 1887 void os::print_os_info(outputStream* st) { 1888 st->print("OS:"); 1889 1890 // Try to identify popular distros. 1891 // Most Linux distributions have /etc/XXX-release file, which contains 1892 // the OS version string. Some have more than one /etc/XXX-release file 1893 // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.), 1894 // so the order is important. 1895 if (!_print_ascii_file("/etc/mandrake-release", st) && 1896 !_print_ascii_file("/etc/sun-release", st) && 1897 !_print_ascii_file("/etc/redhat-release", st) && 1898 !_print_ascii_file("/etc/SuSE-release", st) && 1899 !_print_ascii_file("/etc/turbolinux-release", st) && 1900 !_print_ascii_file("/etc/gentoo-release", st) && 1901 !_print_ascii_file("/etc/debian_version", st)) { 1902 st->print("Linux"); 1903 } 1904 st->cr(); 1905 1906 // kernel 1907 st->print("uname:"); 1908 struct utsname name; 1909 uname(&name); 1910 st->print(name.sysname); st->print(" "); 1911 st->print(name.release); st->print(" "); 1912 st->print(name.version); st->print(" "); 1913 st->print(name.machine); 1914 st->cr(); 1915 1916 // Print warning if unsafe chroot environment detected 1917 if (unsafe_chroot_detected) { 1918 st->print("WARNING!! "); 1919 st->print_cr(unstable_chroot_error); 1920 } 1921 1922 // libc, pthread 1923 st->print("libc:"); 1924 st->print(os::Linux::glibc_version()); st->print(" "); 1925 st->print(os::Linux::libpthread_version()); st->print(" "); 1926 if (os::Linux::is_LinuxThreads()) { 1927 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); 1928 } 1929 st->cr(); 1930 1931 // rlimit 1932 st->print("rlimit:"); 1933 struct rlimit rlim; 1934 1935 st->print(" STACK "); 1936 getrlimit(RLIMIT_STACK, &rlim); 1937 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1938 else st->print("%uk", rlim.rlim_cur >> 10); 1939 1940 st->print(", CORE "); 1941 getrlimit(RLIMIT_CORE, &rlim); 1942 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1943 else st->print("%uk", rlim.rlim_cur >> 10); 1944 1945 st->print(", NPROC "); 1946 getrlimit(RLIMIT_NPROC, &rlim); 1947 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1948 else st->print("%d", rlim.rlim_cur); 1949 1950 st->print(", NOFILE "); 1951 getrlimit(RLIMIT_NOFILE, &rlim); 1952 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1953 else st->print("%d", rlim.rlim_cur); 1954 1955 st->print(", AS "); 1956 getrlimit(RLIMIT_AS, &rlim); 1957 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); 1958 else st->print("%uk", rlim.rlim_cur >> 10); 1959 st->cr(); 1960 1961 // load average 1962 st->print("load average:"); 1963 double loadavg[3]; 1964 os::loadavg(loadavg, 3); 1965 st->print("%0.02f %0.02f %0.02f", loadavg[0], loadavg[1], loadavg[2]); 1966 st->cr(); 1967 } 1968 1969 void os::print_memory_info(outputStream* st) { 1970 1971 st->print("Memory:"); 1972 st->print(" %dk page", os::vm_page_size()>>10); 1973 1974 // values in struct sysinfo are "unsigned long" 1975 struct sysinfo si; 1976 sysinfo(&si); 1977 1978 st->print(", physical " UINT64_FORMAT "k", 1979 os::physical_memory() >> 10); 1980 st->print("(" UINT64_FORMAT "k free)", 1981 os::available_memory() >> 10); 1982 st->print(", swap " UINT64_FORMAT "k", 1983 ((jlong)si.totalswap * si.mem_unit) >> 10); 1984 st->print("(" UINT64_FORMAT "k free)", 1985 ((jlong)si.freeswap * si.mem_unit) >> 10); 1986 st->cr(); 1987 } 1988 1989 // Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific 1990 // but they're the same for all the linux arch that we support 1991 // and they're the same for solaris but there's no common place to put this. 1992 const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR", 1993 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG", 1994 "ILL_COPROC", "ILL_BADSTK" }; 1995 1996 const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV", 1997 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES", 1998 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" }; 1999 2000 const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" }; 2001 2002 const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" }; 2003 2004 void os::print_siginfo(outputStream* st, void* siginfo) { 2005 st->print("siginfo:"); 2006 2007 const int buflen = 100; 2008 char buf[buflen]; 2009 siginfo_t *si = (siginfo_t*)siginfo; 2010 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen)); 2011 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) { 2012 st->print("si_errno=%s", buf); 2013 } else { 2014 st->print("si_errno=%d", si->si_errno); 2015 } 2016 const int c = si->si_code; 2017 assert(c > 0, "unexpected si_code"); 2018 switch (si->si_signo) { 2019 case SIGILL: 2020 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]); 2021 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2022 break; 2023 case SIGFPE: 2024 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]); 2025 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2026 break; 2027 case SIGSEGV: 2028 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]); 2029 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2030 break; 2031 case SIGBUS: 2032 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]); 2033 st->print(", si_addr=" PTR_FORMAT, si->si_addr); 2034 break; 2035 default: 2036 st->print(", si_code=%d", si->si_code); 2037 // no si_addr 2038 } 2039 2040 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) && 2041 UseSharedSpaces) { 2042 FileMapInfo* mapinfo = FileMapInfo::current_info(); 2043 if (mapinfo->is_in_shared_space(si->si_addr)) { 2044 st->print("\n\nError accessing class data sharing archive." \ 2045 " Mapped file inaccessible during execution, " \ 2046 " possible disk/network problem."); 2047 } 2048 } 2049 st->cr(); 2050 } 2051 2052 2053 static void print_signal_handler(outputStream* st, int sig, 2054 char* buf, size_t buflen); 2055 2056 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) { 2057 st->print_cr("Signal Handlers:"); 2058 print_signal_handler(st, SIGSEGV, buf, buflen); 2059 print_signal_handler(st, SIGBUS , buf, buflen); 2060 print_signal_handler(st, SIGFPE , buf, buflen); 2061 print_signal_handler(st, SIGPIPE, buf, buflen); 2062 print_signal_handler(st, SIGXFSZ, buf, buflen); 2063 print_signal_handler(st, SIGILL , buf, buflen); 2064 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen); 2065 print_signal_handler(st, SR_signum, buf, buflen); 2066 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen); 2067 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen); 2068 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen); 2069 print_signal_handler(st, BREAK_SIGNAL, buf, buflen); 2070 } 2071 2072 static char saved_jvm_path[MAXPATHLEN] = {0}; 2073 2074 // Find the full path to the current module, libjvm.so or libjvm_g.so 2075 void os::jvm_path(char *buf, jint len) { 2076 // Error checking. 2077 if (len < MAXPATHLEN) { 2078 assert(false, "must use a large-enough buffer"); 2079 buf[0] = '\0'; 2080 return; 2081 } 2082 // Lazy resolve the path to current module. 2083 if (saved_jvm_path[0] != 0) { 2084 strcpy(buf, saved_jvm_path); 2085 return; 2086 } 2087 2088 char dli_fname[MAXPATHLEN]; 2089 bool ret = dll_address_to_library_name( 2090 CAST_FROM_FN_PTR(address, os::jvm_path), 2091 dli_fname, sizeof(dli_fname), NULL); 2092 assert(ret != 0, "cannot locate libjvm"); 2093 if (realpath(dli_fname, buf) == NULL) 2094 return; 2095 2096 if (strcmp(Arguments::sun_java_launcher(), "gamma") == 0) { 2097 // Support for the gamma launcher. Typical value for buf is 2098 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at 2099 // the right place in the string, then assume we are installed in a JDK and 2100 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix 2101 // up the path so it looks like libjvm.so is installed there (append a 2102 // fake suffix hotspot/libjvm.so). 2103 const char *p = buf + strlen(buf) - 1; 2104 for (int count = 0; p > buf && count < 5; ++count) { 2105 for (--p; p > buf && *p != '/'; --p) 2106 /* empty */ ; 2107 } 2108 2109 if (strncmp(p, "/jre/lib/", 9) != 0) { 2110 // Look for JAVA_HOME in the environment. 2111 char* java_home_var = ::getenv("JAVA_HOME"); 2112 if (java_home_var != NULL && java_home_var[0] != 0) { 2113 // Check the current module name "libjvm.so" or "libjvm_g.so". 2114 p = strrchr(buf, '/'); 2115 assert(strstr(p, "/libjvm") == p, "invalid library name"); 2116 p = strstr(p, "_g") ? "_g" : ""; 2117 2118 if (realpath(java_home_var, buf) == NULL) 2119 return; 2120 sprintf(buf + strlen(buf), "/jre/lib/%s", cpu_arch); 2121 if (0 == access(buf, F_OK)) { 2122 // Use current module name "libjvm[_g].so" instead of 2123 // "libjvm"debug_only("_g")".so" since for fastdebug version 2124 // we should have "libjvm.so" but debug_only("_g") adds "_g"! 2125 // It is used when we are choosing the HPI library's name 2126 // "libhpi[_g].so" in hpi::initialize_get_interface(). 2127 sprintf(buf + strlen(buf), "/hotspot/libjvm%s.so", p); 2128 } else { 2129 // Go back to path of .so 2130 if (realpath(dli_fname, buf) == NULL) 2131 return; 2132 } 2133 } 2134 } 2135 } 2136 2137 strcpy(saved_jvm_path, buf); 2138 } 2139 2140 void os::print_jni_name_prefix_on(outputStream* st, int args_size) { 2141 // no prefix required, not even "_" 2142 } 2143 2144 void os::print_jni_name_suffix_on(outputStream* st, int args_size) { 2145 // no suffix required 2146 } 2147 2148 //////////////////////////////////////////////////////////////////////////////// 2149 // sun.misc.Signal support 2150 2151 static volatile jint sigint_count = 0; 2152 2153 static void 2154 UserHandler(int sig, void *siginfo, void *context) { 2155 // 4511530 - sem_post is serialized and handled by the manager thread. When 2156 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We 2157 // don't want to flood the manager thread with sem_post requests. 2158 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) 2159 return; 2160 2161 // Ctrl-C is pressed during error reporting, likely because the error 2162 // handler fails to abort. Let VM die immediately. 2163 if (sig == SIGINT && is_error_reported()) { 2164 os::die(); 2165 } 2166 2167 os::signal_notify(sig); 2168 } 2169 2170 void* os::user_handler() { 2171 return CAST_FROM_FN_PTR(void*, UserHandler); 2172 } 2173 2174 extern "C" { 2175 typedef void (*sa_handler_t)(int); 2176 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 2177 } 2178 2179 void* os::signal(int signal_number, void* handler) { 2180 struct sigaction sigAct, oldSigAct; 2181 2182 sigfillset(&(sigAct.sa_mask)); 2183 sigAct.sa_flags = SA_RESTART|SA_SIGINFO; 2184 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler); 2185 2186 if (sigaction(signal_number, &sigAct, &oldSigAct)) { 2187 // -1 means registration failed 2188 return (void *)-1; 2189 } 2190 2191 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler); 2192 } 2193 2194 void os::signal_raise(int signal_number) { 2195 ::raise(signal_number); 2196 } 2197 2198 /* 2199 * The following code is moved from os.cpp for making this 2200 * code platform specific, which it is by its very nature. 2201 */ 2202 2203 // Will be modified when max signal is changed to be dynamic 2204 int os::sigexitnum_pd() { 2205 return NSIG; 2206 } 2207 2208 // a counter for each possible signal value 2209 static volatile jint pending_signals[NSIG+1] = { 0 }; 2210 2211 // Linux(POSIX) specific hand shaking semaphore. 2212 static sem_t sig_sem; 2213 2214 void os::signal_init_pd() { 2215 // Initialize signal structures 2216 ::memset((void*)pending_signals, 0, sizeof(pending_signals)); 2217 2218 // Initialize signal semaphore 2219 ::sem_init(&sig_sem, 0, 0); 2220 } 2221 2222 void os::signal_notify(int sig) { 2223 Atomic::inc(&pending_signals[sig]); 2224 ::sem_post(&sig_sem); 2225 } 2226 2227 static int check_pending_signals(bool wait) { 2228 Atomic::store(0, &sigint_count); 2229 for (;;) { 2230 for (int i = 0; i < NSIG + 1; i++) { 2231 jint n = pending_signals[i]; 2232 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) { 2233 return i; 2234 } 2235 } 2236 if (!wait) { 2237 return -1; 2238 } 2239 JavaThread *thread = JavaThread::current(); 2240 ThreadBlockInVM tbivm(thread); 2241 2242 bool threadIsSuspended; 2243 do { 2244 thread->set_suspend_equivalent(); 2245 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 2246 ::sem_wait(&sig_sem); 2247 2248 // were we externally suspended while we were waiting? 2249 threadIsSuspended = thread->handle_special_suspend_equivalent_condition(); 2250 if (threadIsSuspended) { 2251 // 2252 // The semaphore has been incremented, but while we were waiting 2253 // another thread suspended us. We don't want to continue running 2254 // while suspended because that would surprise the thread that 2255 // suspended us. 2256 // 2257 ::sem_post(&sig_sem); 2258 2259 thread->java_suspend_self(); 2260 } 2261 } while (threadIsSuspended); 2262 } 2263 } 2264 2265 int os::signal_lookup() { 2266 return check_pending_signals(false); 2267 } 2268 2269 int os::signal_wait() { 2270 return check_pending_signals(true); 2271 } 2272 2273 //////////////////////////////////////////////////////////////////////////////// 2274 // Virtual Memory 2275 2276 int os::vm_page_size() { 2277 // Seems redundant as all get out 2278 assert(os::Linux::page_size() != -1, "must call os::init"); 2279 return os::Linux::page_size(); 2280 } 2281 2282 // Solaris allocates memory by pages. 2283 int os::vm_allocation_granularity() { 2284 assert(os::Linux::page_size() != -1, "must call os::init"); 2285 return os::Linux::page_size(); 2286 } 2287 2288 // Rationale behind this function: 2289 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable 2290 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get 2291 // samples for JITted code. Here we create private executable mapping over the code cache 2292 // and then we can use standard (well, almost, as mapping can change) way to provide 2293 // info for the reporting script by storing timestamp and location of symbol 2294 void linux_wrap_code(char* base, size_t size) { 2295 static volatile jint cnt = 0; 2296 2297 if (!UseOprofile) { 2298 return; 2299 } 2300 2301 char buf[40]; 2302 int num = Atomic::add(1, &cnt); 2303 2304 sprintf(buf, "/tmp/hs-vm-%d-%d", os::current_process_id(), num); 2305 unlink(buf); 2306 2307 int fd = open(buf, O_CREAT | O_RDWR, S_IRWXU); 2308 2309 if (fd != -1) { 2310 off_t rv = lseek(fd, size-2, SEEK_SET); 2311 if (rv != (off_t)-1) { 2312 if (write(fd, "", 1) == 1) { 2313 mmap(base, size, 2314 PROT_READ|PROT_WRITE|PROT_EXEC, 2315 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0); 2316 } 2317 } 2318 close(fd); 2319 unlink(buf); 2320 } 2321 } 2322 2323 // NOTE: Linux kernel does not really reserve the pages for us. 2324 // All it does is to check if there are enough free pages 2325 // left at the time of mmap(). This could be a potential 2326 // problem. 2327 bool os::commit_memory(char* addr, size_t size, bool exec) { 2328 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; 2329 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, 2330 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2331 return res != (uintptr_t) MAP_FAILED; 2332 } 2333 2334 bool os::commit_memory(char* addr, size_t size, size_t alignment_hint, 2335 bool exec) { 2336 return commit_memory(addr, size, exec); 2337 } 2338 2339 void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) { } 2340 2341 void os::free_memory(char *addr, size_t bytes) { 2342 ::mmap(addr, bytes, PROT_READ | PROT_WRITE, 2343 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); 2344 } 2345 2346 void os::numa_make_global(char *addr, size_t bytes) { 2347 Linux::numa_interleave_memory(addr, bytes); 2348 } 2349 2350 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { 2351 Linux::numa_tonode_memory(addr, bytes, lgrp_hint); 2352 } 2353 2354 bool os::numa_topology_changed() { return false; } 2355 2356 size_t os::numa_get_groups_num() { 2357 int max_node = Linux::numa_max_node(); 2358 return max_node > 0 ? max_node + 1 : 1; 2359 } 2360 2361 int os::numa_get_group_id() { 2362 int cpu_id = Linux::sched_getcpu(); 2363 if (cpu_id != -1) { 2364 int lgrp_id = Linux::get_node_by_cpu(cpu_id); 2365 if (lgrp_id != -1) { 2366 return lgrp_id; 2367 } 2368 } 2369 return 0; 2370 } 2371 2372 size_t os::numa_get_leaf_groups(int *ids, size_t size) { 2373 for (size_t i = 0; i < size; i++) { 2374 ids[i] = i; 2375 } 2376 return size; 2377 } 2378 2379 bool os::get_page_info(char *start, page_info* info) { 2380 return false; 2381 } 2382 2383 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) { 2384 return end; 2385 } 2386 2387 extern "C" void numa_warn(int number, char *where, ...) { } 2388 extern "C" void numa_error(char *where) { } 2389 2390 2391 // If we are running with libnuma version > 2, then we should 2392 // be trying to use symbols with versions 1.1 2393 // If we are running with earlier version, which did not have symbol versions, 2394 // we should use the base version. 2395 void* os::Linux::libnuma_dlsym(void* handle, const char *name) { 2396 void *f = dlvsym(handle, name, "libnuma_1.1"); 2397 if (f == NULL) { 2398 f = dlsym(handle, name); 2399 } 2400 return f; 2401 } 2402 2403 bool os::Linux::libnuma_init() { 2404 // sched_getcpu() should be in libc. 2405 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, 2406 dlsym(RTLD_DEFAULT, "sched_getcpu"))); 2407 2408 if (sched_getcpu() != -1) { // Does it work? 2409 void *handle = dlopen("libnuma.so.1", RTLD_LAZY); 2410 if (handle != NULL) { 2411 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, 2412 libnuma_dlsym(handle, "numa_node_to_cpus"))); 2413 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, 2414 libnuma_dlsym(handle, "numa_max_node"))); 2415 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, 2416 libnuma_dlsym(handle, "numa_available"))); 2417 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, 2418 libnuma_dlsym(handle, "numa_tonode_memory"))); 2419 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, 2420 libnuma_dlsym(handle, "numa_interleave_memory"))); 2421 2422 2423 if (numa_available() != -1) { 2424 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); 2425 // Create a cpu -> node mapping 2426 _cpu_to_node = new (ResourceObj::C_HEAP) GrowableArray<int>(0, true); 2427 rebuild_cpu_to_node_map(); 2428 return true; 2429 } 2430 } 2431 } 2432 return false; 2433 } 2434 2435 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. 2436 // The table is later used in get_node_by_cpu(). 2437 void os::Linux::rebuild_cpu_to_node_map() { 2438 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure 2439 // in libnuma (possible values are starting from 16, 2440 // and continuing up with every other power of 2, but less 2441 // than the maximum number of CPUs supported by kernel), and 2442 // is a subject to change (in libnuma version 2 the requirements 2443 // are more reasonable) we'll just hardcode the number they use 2444 // in the library. 2445 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; 2446 2447 size_t cpu_num = os::active_processor_count(); 2448 size_t cpu_map_size = NCPUS / BitsPerCLong; 2449 size_t cpu_map_valid_size = 2450 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); 2451 2452 cpu_to_node()->clear(); 2453 cpu_to_node()->at_grow(cpu_num - 1); 2454 size_t node_num = numa_get_groups_num(); 2455 2456 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size); 2457 for (size_t i = 0; i < node_num; i++) { 2458 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { 2459 for (size_t j = 0; j < cpu_map_valid_size; j++) { 2460 if (cpu_map[j] != 0) { 2461 for (size_t k = 0; k < BitsPerCLong; k++) { 2462 if (cpu_map[j] & (1UL << k)) { 2463 cpu_to_node()->at_put(j * BitsPerCLong + k, i); 2464 } 2465 } 2466 } 2467 } 2468 } 2469 } 2470 FREE_C_HEAP_ARRAY(unsigned long, cpu_map); 2471 } 2472 2473 int os::Linux::get_node_by_cpu(int cpu_id) { 2474 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { 2475 return cpu_to_node()->at(cpu_id); 2476 } 2477 return -1; 2478 } 2479 2480 GrowableArray<int>* os::Linux::_cpu_to_node; 2481 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; 2482 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; 2483 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; 2484 os::Linux::numa_available_func_t os::Linux::_numa_available; 2485 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; 2486 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; 2487 unsigned long* os::Linux::_numa_all_nodes; 2488 2489 bool os::uncommit_memory(char* addr, size_t size) { 2490 return ::mmap(addr, size, PROT_NONE, 2491 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0) 2492 != MAP_FAILED; 2493 } 2494 2495 static address _highest_vm_reserved_address = NULL; 2496 2497 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory 2498 // at 'requested_addr'. If there are existing memory mappings at the same 2499 // location, however, they will be overwritten. If 'fixed' is false, 2500 // 'requested_addr' is only treated as a hint, the return value may or 2501 // may not start from the requested address. Unlike Linux mmap(), this 2502 // function returns NULL to indicate failure. 2503 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) { 2504 char * addr; 2505 int flags; 2506 2507 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS; 2508 if (fixed) { 2509 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address"); 2510 flags |= MAP_FIXED; 2511 } 2512 2513 // Map uncommitted pages PROT_READ and PROT_WRITE, change access 2514 // to PROT_EXEC if executable when we commit the page. 2515 addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE, 2516 flags, -1, 0); 2517 2518 if (addr != MAP_FAILED) { 2519 // anon_mmap() should only get called during VM initialization, 2520 // don't need lock (actually we can skip locking even it can be called 2521 // from multiple threads, because _highest_vm_reserved_address is just a 2522 // hint about the upper limit of non-stack memory regions.) 2523 if ((address)addr + bytes > _highest_vm_reserved_address) { 2524 _highest_vm_reserved_address = (address)addr + bytes; 2525 } 2526 } 2527 2528 return addr == MAP_FAILED ? NULL : addr; 2529 } 2530 2531 // Don't update _highest_vm_reserved_address, because there might be memory 2532 // regions above addr + size. If so, releasing a memory region only creates 2533 // a hole in the address space, it doesn't help prevent heap-stack collision. 2534 // 2535 static int anon_munmap(char * addr, size_t size) { 2536 return ::munmap(addr, size) == 0; 2537 } 2538 2539 char* os::reserve_memory(size_t bytes, char* requested_addr, 2540 size_t alignment_hint) { 2541 return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); 2542 } 2543 2544 bool os::release_memory(char* addr, size_t size) { 2545 return anon_munmap(addr, size); 2546 } 2547 2548 static address highest_vm_reserved_address() { 2549 return _highest_vm_reserved_address; 2550 } 2551 2552 static bool linux_mprotect(char* addr, size_t size, int prot) { 2553 // Linux wants the mprotect address argument to be page aligned. 2554 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size()); 2555 2556 // According to SUSv3, mprotect() should only be used with mappings 2557 // established by mmap(), and mmap() always maps whole pages. Unaligned 2558 // 'addr' likely indicates problem in the VM (e.g. trying to change 2559 // protection of malloc'ed or statically allocated memory). Check the 2560 // caller if you hit this assert. 2561 assert(addr == bottom, "sanity check"); 2562 2563 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size()); 2564 return ::mprotect(bottom, size, prot) == 0; 2565 } 2566 2567 // Set protections specified 2568 bool os::protect_memory(char* addr, size_t bytes, ProtType prot, 2569 bool is_committed) { 2570 unsigned int p = 0; 2571 switch (prot) { 2572 case MEM_PROT_NONE: p = PROT_NONE; break; 2573 case MEM_PROT_READ: p = PROT_READ; break; 2574 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break; 2575 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break; 2576 default: 2577 ShouldNotReachHere(); 2578 } 2579 // is_committed is unused. 2580 return linux_mprotect(addr, bytes, p); 2581 } 2582 2583 bool os::guard_memory(char* addr, size_t size) { 2584 return linux_mprotect(addr, size, PROT_NONE); 2585 } 2586 2587 bool os::unguard_memory(char* addr, size_t size) { 2588 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); 2589 } 2590 2591 // Large page support 2592 2593 static size_t _large_page_size = 0; 2594 2595 bool os::large_page_init() { 2596 if (!UseLargePages) return false; 2597 2598 if (LargePageSizeInBytes) { 2599 _large_page_size = LargePageSizeInBytes; 2600 } else { 2601 // large_page_size on Linux is used to round up heap size. x86 uses either 2602 // 2M or 4M page, depending on whether PAE (Physical Address Extensions) 2603 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use 2604 // page as large as 256M. 2605 // 2606 // Here we try to figure out page size by parsing /proc/meminfo and looking 2607 // for a line with the following format: 2608 // Hugepagesize: 2048 kB 2609 // 2610 // If we can't determine the value (e.g. /proc is not mounted, or the text 2611 // format has been changed), we'll use the largest page size supported by 2612 // the processor. 2613 2614 #ifndef ZERO 2615 _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M); 2616 #endif // ZERO 2617 2618 FILE *fp = fopen("/proc/meminfo", "r"); 2619 if (fp) { 2620 while (!feof(fp)) { 2621 int x = 0; 2622 char buf[16]; 2623 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { 2624 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { 2625 _large_page_size = x * K; 2626 break; 2627 } 2628 } else { 2629 // skip to next line 2630 for (;;) { 2631 int ch = fgetc(fp); 2632 if (ch == EOF || ch == (int)'\n') break; 2633 } 2634 } 2635 } 2636 fclose(fp); 2637 } 2638 } 2639 2640 const size_t default_page_size = (size_t)Linux::page_size(); 2641 if (_large_page_size > default_page_size) { 2642 _page_sizes[0] = _large_page_size; 2643 _page_sizes[1] = default_page_size; 2644 _page_sizes[2] = 0; 2645 } 2646 2647 // Large page support is available on 2.6 or newer kernel, some vendors 2648 // (e.g. Redhat) have backported it to their 2.4 based distributions. 2649 // We optimistically assume the support is available. If later it turns out 2650 // not true, VM will automatically switch to use regular page size. 2651 return true; 2652 } 2653 2654 #ifndef SHM_HUGETLB 2655 #define SHM_HUGETLB 04000 2656 #endif 2657 2658 char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) { 2659 // "exec" is passed in but not used. Creating the shared image for 2660 // the code cache doesn't have an SHM_X executable permission to check. 2661 assert(UseLargePages, "only for large pages"); 2662 2663 key_t key = IPC_PRIVATE; 2664 char *addr; 2665 2666 bool warn_on_failure = UseLargePages && 2667 (!FLAG_IS_DEFAULT(UseLargePages) || 2668 !FLAG_IS_DEFAULT(LargePageSizeInBytes) 2669 ); 2670 char msg[128]; 2671 2672 // Create a large shared memory region to attach to based on size. 2673 // Currently, size is the total size of the heap 2674 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W); 2675 if (shmid == -1) { 2676 // Possible reasons for shmget failure: 2677 // 1. shmmax is too small for Java heap. 2678 // > check shmmax value: cat /proc/sys/kernel/shmmax 2679 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax 2680 // 2. not enough large page memory. 2681 // > check available large pages: cat /proc/meminfo 2682 // > increase amount of large pages: 2683 // echo new_value > /proc/sys/vm/nr_hugepages 2684 // Note 1: different Linux may use different name for this property, 2685 // e.g. on Redhat AS-3 it is "hugetlb_pool". 2686 // Note 2: it's possible there's enough physical memory available but 2687 // they are so fragmented after a long run that they can't 2688 // coalesce into large pages. Try to reserve large pages when 2689 // the system is still "fresh". 2690 if (warn_on_failure) { 2691 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); 2692 warning(msg); 2693 } 2694 return NULL; 2695 } 2696 2697 // attach to the region 2698 addr = (char*)shmat(shmid, NULL, 0); 2699 int err = errno; 2700 2701 // Remove shmid. If shmat() is successful, the actual shared memory segment 2702 // will be deleted when it's detached by shmdt() or when the process 2703 // terminates. If shmat() is not successful this will remove the shared 2704 // segment immediately. 2705 shmctl(shmid, IPC_RMID, NULL); 2706 2707 if ((intptr_t)addr == -1) { 2708 if (warn_on_failure) { 2709 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); 2710 warning(msg); 2711 } 2712 return NULL; 2713 } 2714 2715 return addr; 2716 } 2717 2718 bool os::release_memory_special(char* base, size_t bytes) { 2719 // detaching the SHM segment will also delete it, see reserve_memory_special() 2720 int rslt = shmdt(base); 2721 return rslt == 0; 2722 } 2723 2724 size_t os::large_page_size() { 2725 return _large_page_size; 2726 } 2727 2728 // Linux does not support anonymous mmap with large page memory. The only way 2729 // to reserve large page memory without file backing is through SysV shared 2730 // memory API. The entire memory region is committed and pinned upfront. 2731 // Hopefully this will change in the future... 2732 bool os::can_commit_large_page_memory() { 2733 return false; 2734 } 2735 2736 bool os::can_execute_large_page_memory() { 2737 return false; 2738 } 2739 2740 // Reserve memory at an arbitrary address, only if that area is 2741 // available (and not reserved for something else). 2742 2743 char* os::attempt_reserve_memory_at(size_t bytes, char* requested_addr) { 2744 const int max_tries = 10; 2745 char* base[max_tries]; 2746 size_t size[max_tries]; 2747 const size_t gap = 0x000000; 2748 2749 // Assert only that the size is a multiple of the page size, since 2750 // that's all that mmap requires, and since that's all we really know 2751 // about at this low abstraction level. If we need higher alignment, 2752 // we can either pass an alignment to this method or verify alignment 2753 // in one of the methods further up the call chain. See bug 5044738. 2754 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block"); 2755 2756 // Repeatedly allocate blocks until the block is allocated at the 2757 // right spot. Give up after max_tries. Note that reserve_memory() will 2758 // automatically update _highest_vm_reserved_address if the call is 2759 // successful. The variable tracks the highest memory address every reserved 2760 // by JVM. It is used to detect heap-stack collision if running with 2761 // fixed-stack LinuxThreads. Because here we may attempt to reserve more 2762 // space than needed, it could confuse the collision detecting code. To 2763 // solve the problem, save current _highest_vm_reserved_address and 2764 // calculate the correct value before return. 2765 address old_highest = _highest_vm_reserved_address; 2766 2767 // Linux mmap allows caller to pass an address as hint; give it a try first, 2768 // if kernel honors the hint then we can return immediately. 2769 char * addr = anon_mmap(requested_addr, bytes, false); 2770 if (addr == requested_addr) { 2771 return requested_addr; 2772 } 2773 2774 if (addr != NULL) { 2775 // mmap() is successful but it fails to reserve at the requested address 2776 anon_munmap(addr, bytes); 2777 } 2778 2779 int i; 2780 for (i = 0; i < max_tries; ++i) { 2781 base[i] = reserve_memory(bytes); 2782 2783 if (base[i] != NULL) { 2784 // Is this the block we wanted? 2785 if (base[i] == requested_addr) { 2786 size[i] = bytes; 2787 break; 2788 } 2789 2790 // Does this overlap the block we wanted? Give back the overlapped 2791 // parts and try again. 2792 2793 size_t top_overlap = requested_addr + (bytes + gap) - base[i]; 2794 if (top_overlap >= 0 && top_overlap < bytes) { 2795 unmap_memory(base[i], top_overlap); 2796 base[i] += top_overlap; 2797 size[i] = bytes - top_overlap; 2798 } else { 2799 size_t bottom_overlap = base[i] + bytes - requested_addr; 2800 if (bottom_overlap >= 0 && bottom_overlap < bytes) { 2801 unmap_memory(requested_addr, bottom_overlap); 2802 size[i] = bytes - bottom_overlap; 2803 } else { 2804 size[i] = bytes; 2805 } 2806 } 2807 } 2808 } 2809 2810 // Give back the unused reserved pieces. 2811 2812 for (int j = 0; j < i; ++j) { 2813 if (base[j] != NULL) { 2814 unmap_memory(base[j], size[j]); 2815 } 2816 } 2817 2818 if (i < max_tries) { 2819 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes); 2820 return requested_addr; 2821 } else { 2822 _highest_vm_reserved_address = old_highest; 2823 return NULL; 2824 } 2825 } 2826 2827 size_t os::read(int fd, void *buf, unsigned int nBytes) { 2828 return ::read(fd, buf, nBytes); 2829 } 2830 2831 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation. 2832 // Solaris uses poll(), linux uses park(). 2833 // Poll() is likely a better choice, assuming that Thread.interrupt() 2834 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with 2835 // SIGSEGV, see 4355769. 2836 2837 const int NANOSECS_PER_MILLISECS = 1000000; 2838 2839 int os::sleep(Thread* thread, jlong millis, bool interruptible) { 2840 assert(thread == Thread::current(), "thread consistency check"); 2841 2842 ParkEvent * const slp = thread->_SleepEvent ; 2843 slp->reset() ; 2844 OrderAccess::fence() ; 2845 2846 if (interruptible) { 2847 jlong prevtime = javaTimeNanos(); 2848 2849 for (;;) { 2850 if (os::is_interrupted(thread, true)) { 2851 return OS_INTRPT; 2852 } 2853 2854 jlong newtime = javaTimeNanos(); 2855 2856 if (newtime - prevtime < 0) { 2857 // time moving backwards, should only happen if no monotonic clock 2858 // not a guarantee() because JVM should not abort on kernel/glibc bugs 2859 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 2860 } else { 2861 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS; 2862 } 2863 2864 if(millis <= 0) { 2865 return OS_OK; 2866 } 2867 2868 prevtime = newtime; 2869 2870 { 2871 assert(thread->is_Java_thread(), "sanity check"); 2872 JavaThread *jt = (JavaThread *) thread; 2873 ThreadBlockInVM tbivm(jt); 2874 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */); 2875 2876 jt->set_suspend_equivalent(); 2877 // cleared by handle_special_suspend_equivalent_condition() or 2878 // java_suspend_self() via check_and_wait_while_suspended() 2879 2880 slp->park(millis); 2881 2882 // were we externally suspended while we were waiting? 2883 jt->check_and_wait_while_suspended(); 2884 } 2885 } 2886 } else { 2887 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 2888 jlong prevtime = javaTimeNanos(); 2889 2890 for (;;) { 2891 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on 2892 // the 1st iteration ... 2893 jlong newtime = javaTimeNanos(); 2894 2895 if (newtime - prevtime < 0) { 2896 // time moving backwards, should only happen if no monotonic clock 2897 // not a guarantee() because JVM should not abort on kernel/glibc bugs 2898 assert(!Linux::supports_monotonic_clock(), "time moving backwards"); 2899 } else { 2900 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS; 2901 } 2902 2903 if(millis <= 0) break ; 2904 2905 prevtime = newtime; 2906 slp->park(millis); 2907 } 2908 return OS_OK ; 2909 } 2910 } 2911 2912 int os::naked_sleep() { 2913 // %% make the sleep time an integer flag. for now use 1 millisec. 2914 return os::sleep(Thread::current(), 1, false); 2915 } 2916 2917 // Sleep forever; naked call to OS-specific sleep; use with CAUTION 2918 void os::infinite_sleep() { 2919 while (true) { // sleep forever ... 2920 ::sleep(100); // ... 100 seconds at a time 2921 } 2922 } 2923 2924 // Used to convert frequent JVM_Yield() to nops 2925 bool os::dont_yield() { 2926 return DontYieldALot; 2927 } 2928 2929 void os::yield() { 2930 sched_yield(); 2931 } 2932 2933 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;} 2934 2935 void os::yield_all(int attempts) { 2936 // Yields to all threads, including threads with lower priorities 2937 // Threads on Linux are all with same priority. The Solaris style 2938 // os::yield_all() with nanosleep(1ms) is not necessary. 2939 sched_yield(); 2940 } 2941 2942 // Called from the tight loops to possibly influence time-sharing heuristics 2943 void os::loop_breaker(int attempts) { 2944 os::yield_all(attempts); 2945 } 2946 2947 //////////////////////////////////////////////////////////////////////////////// 2948 // thread priority support 2949 2950 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER 2951 // only supports dynamic priority, static priority must be zero. For real-time 2952 // applications, Linux supports SCHED_RR which allows static priority (1-99). 2953 // However, for large multi-threaded applications, SCHED_RR is not only slower 2954 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out 2955 // of 5 runs - Sep 2005). 2956 // 2957 // The following code actually changes the niceness of kernel-thread/LWP. It 2958 // has an assumption that setpriority() only modifies one kernel-thread/LWP, 2959 // not the entire user process, and user level threads are 1:1 mapped to kernel 2960 // threads. It has always been the case, but could change in the future. For 2961 // this reason, the code should not be used as default (ThreadPriorityPolicy=0). 2962 // It is only used when ThreadPriorityPolicy=1 and requires root privilege. 2963 2964 int os::java_to_os_priority[MaxPriority + 1] = { 2965 19, // 0 Entry should never be used 2966 2967 4, // 1 MinPriority 2968 3, // 2 2969 2, // 3 2970 2971 1, // 4 2972 0, // 5 NormPriority 2973 -1, // 6 2974 2975 -2, // 7 2976 -3, // 8 2977 -4, // 9 NearMaxPriority 2978 2979 -5 // 10 MaxPriority 2980 }; 2981 2982 static int prio_init() { 2983 if (ThreadPriorityPolicy == 1) { 2984 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1 2985 // if effective uid is not root. Perhaps, a more elegant way of doing 2986 // this is to test CAP_SYS_NICE capability, but that will require libcap.so 2987 if (geteuid() != 0) { 2988 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) { 2989 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux"); 2990 } 2991 ThreadPriorityPolicy = 0; 2992 } 2993 } 2994 return 0; 2995 } 2996 2997 OSReturn os::set_native_priority(Thread* thread, int newpri) { 2998 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; 2999 3000 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); 3001 return (ret == 0) ? OS_OK : OS_ERR; 3002 } 3003 3004 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) { 3005 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) { 3006 *priority_ptr = java_to_os_priority[NormPriority]; 3007 return OS_OK; 3008 } 3009 3010 errno = 0; 3011 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 3012 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR); 3013 } 3014 3015 // Hint to the underlying OS that a task switch would not be good. 3016 // Void return because it's a hint and can fail. 3017 void os::hint_no_preempt() {} 3018 3019 //////////////////////////////////////////////////////////////////////////////// 3020 // suspend/resume support 3021 3022 // the low-level signal-based suspend/resume support is a remnant from the 3023 // old VM-suspension that used to be for java-suspension, safepoints etc, 3024 // within hotspot. Now there is a single use-case for this: 3025 // - calling get_thread_pc() on the VMThread by the flat-profiler task 3026 // that runs in the watcher thread. 3027 // The remaining code is greatly simplified from the more general suspension 3028 // code that used to be used. 3029 // 3030 // The protocol is quite simple: 3031 // - suspend: 3032 // - sends a signal to the target thread 3033 // - polls the suspend state of the osthread using a yield loop 3034 // - target thread signal handler (SR_handler) sets suspend state 3035 // and blocks in sigsuspend until continued 3036 // - resume: 3037 // - sets target osthread state to continue 3038 // - sends signal to end the sigsuspend loop in the SR_handler 3039 // 3040 // Note that the SR_lock plays no role in this suspend/resume protocol. 3041 // 3042 3043 static void resume_clear_context(OSThread *osthread) { 3044 osthread->set_ucontext(NULL); 3045 osthread->set_siginfo(NULL); 3046 3047 // notify the suspend action is completed, we have now resumed 3048 osthread->sr.clear_suspended(); 3049 } 3050 3051 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) { 3052 osthread->set_ucontext(context); 3053 osthread->set_siginfo(siginfo); 3054 } 3055 3056 // 3057 // Handler function invoked when a thread's execution is suspended or 3058 // resumed. We have to be careful that only async-safe functions are 3059 // called here (Note: most pthread functions are not async safe and 3060 // should be avoided.) 3061 // 3062 // Note: sigwait() is a more natural fit than sigsuspend() from an 3063 // interface point of view, but sigwait() prevents the signal hander 3064 // from being run. libpthread would get very confused by not having 3065 // its signal handlers run and prevents sigwait()'s use with the 3066 // mutex granting granting signal. 3067 // 3068 // Currently only ever called on the VMThread 3069 // 3070 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) { 3071 // Save and restore errno to avoid confusing native code with EINTR 3072 // after sigsuspend. 3073 int old_errno = errno; 3074 3075 Thread* thread = Thread::current(); 3076 OSThread* osthread = thread->osthread(); 3077 assert(thread->is_VM_thread(), "Must be VMThread"); 3078 // read current suspend action 3079 int action = osthread->sr.suspend_action(); 3080 if (action == SR_SUSPEND) { 3081 suspend_save_context(osthread, siginfo, context); 3082 3083 // Notify the suspend action is about to be completed. do_suspend() 3084 // waits until SR_SUSPENDED is set and then returns. We will wait 3085 // here for a resume signal and that completes the suspend-other 3086 // action. do_suspend/do_resume is always called as a pair from 3087 // the same thread - so there are no races 3088 3089 // notify the caller 3090 osthread->sr.set_suspended(); 3091 3092 sigset_t suspend_set; // signals for sigsuspend() 3093 3094 // get current set of blocked signals and unblock resume signal 3095 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set); 3096 sigdelset(&suspend_set, SR_signum); 3097 3098 // wait here until we are resumed 3099 do { 3100 sigsuspend(&suspend_set); 3101 // ignore all returns until we get a resume signal 3102 } while (osthread->sr.suspend_action() != SR_CONTINUE); 3103 3104 resume_clear_context(osthread); 3105 3106 } else { 3107 assert(action == SR_CONTINUE, "unexpected sr action"); 3108 // nothing special to do - just leave the handler 3109 } 3110 3111 errno = old_errno; 3112 } 3113 3114 3115 static int SR_initialize() { 3116 struct sigaction act; 3117 char *s; 3118 /* Get signal number to use for suspend/resume */ 3119 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) { 3120 int sig = ::strtol(s, 0, 10); 3121 if (sig > 0 || sig < _NSIG) { 3122 SR_signum = sig; 3123 } 3124 } 3125 3126 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS, 3127 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"); 3128 3129 sigemptyset(&SR_sigset); 3130 sigaddset(&SR_sigset, SR_signum); 3131 3132 /* Set up signal handler for suspend/resume */ 3133 act.sa_flags = SA_RESTART|SA_SIGINFO; 3134 act.sa_handler = (void (*)(int)) SR_handler; 3135 3136 // SR_signum is blocked by default. 3137 // 4528190 - We also need to block pthread restart signal (32 on all 3138 // supported Linux platforms). Note that LinuxThreads need to block 3139 // this signal for all threads to work properly. So we don't have 3140 // to use hard-coded signal number when setting up the mask. 3141 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask); 3142 3143 if (sigaction(SR_signum, &act, 0) == -1) { 3144 return -1; 3145 } 3146 3147 // Save signal flag 3148 os::Linux::set_our_sigflags(SR_signum, act.sa_flags); 3149 return 0; 3150 } 3151 3152 static int SR_finalize() { 3153 return 0; 3154 } 3155 3156 3157 // returns true on success and false on error - really an error is fatal 3158 // but this seems the normal response to library errors 3159 static bool do_suspend(OSThread* osthread) { 3160 // mark as suspended and send signal 3161 osthread->sr.set_suspend_action(SR_SUSPEND); 3162 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3163 assert_status(status == 0, status, "pthread_kill"); 3164 3165 // check status and wait until notified of suspension 3166 if (status == 0) { 3167 for (int i = 0; !osthread->sr.is_suspended(); i++) { 3168 os::yield_all(i); 3169 } 3170 osthread->sr.set_suspend_action(SR_NONE); 3171 return true; 3172 } 3173 else { 3174 osthread->sr.set_suspend_action(SR_NONE); 3175 return false; 3176 } 3177 } 3178 3179 static void do_resume(OSThread* osthread) { 3180 assert(osthread->sr.is_suspended(), "thread should be suspended"); 3181 osthread->sr.set_suspend_action(SR_CONTINUE); 3182 3183 int status = pthread_kill(osthread->pthread_id(), SR_signum); 3184 assert_status(status == 0, status, "pthread_kill"); 3185 // check status and wait unit notified of resumption 3186 if (status == 0) { 3187 for (int i = 0; osthread->sr.is_suspended(); i++) { 3188 os::yield_all(i); 3189 } 3190 } 3191 osthread->sr.set_suspend_action(SR_NONE); 3192 } 3193 3194 //////////////////////////////////////////////////////////////////////////////// 3195 // interrupt support 3196 3197 void os::interrupt(Thread* thread) { 3198 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3199 "possibility of dangling Thread pointer"); 3200 3201 OSThread* osthread = thread->osthread(); 3202 3203 if (!osthread->interrupted()) { 3204 osthread->set_interrupted(true); 3205 // More than one thread can get here with the same value of osthread, 3206 // resulting in multiple notifications. We do, however, want the store 3207 // to interrupted() to be visible to other threads before we execute unpark(). 3208 OrderAccess::fence(); 3209 ParkEvent * const slp = thread->_SleepEvent ; 3210 if (slp != NULL) slp->unpark() ; 3211 } 3212 3213 // For JSR166. Unpark even if interrupt status already was set 3214 if (thread->is_Java_thread()) 3215 ((JavaThread*)thread)->parker()->unpark(); 3216 3217 ParkEvent * ev = thread->_ParkEvent ; 3218 if (ev != NULL) ev->unpark() ; 3219 3220 } 3221 3222 bool os::is_interrupted(Thread* thread, bool clear_interrupted) { 3223 assert(Thread::current() == thread || Threads_lock->owned_by_self(), 3224 "possibility of dangling Thread pointer"); 3225 3226 OSThread* osthread = thread->osthread(); 3227 3228 bool interrupted = osthread->interrupted(); 3229 3230 if (interrupted && clear_interrupted) { 3231 osthread->set_interrupted(false); 3232 // consider thread->_SleepEvent->reset() ... optional optimization 3233 } 3234 3235 return interrupted; 3236 } 3237 3238 /////////////////////////////////////////////////////////////////////////////////// 3239 // signal handling (except suspend/resume) 3240 3241 // This routine may be used by user applications as a "hook" to catch signals. 3242 // The user-defined signal handler must pass unrecognized signals to this 3243 // routine, and if it returns true (non-zero), then the signal handler must 3244 // return immediately. If the flag "abort_if_unrecognized" is true, then this 3245 // routine will never retun false (zero), but instead will execute a VM panic 3246 // routine kill the process. 3247 // 3248 // If this routine returns false, it is OK to call it again. This allows 3249 // the user-defined signal handler to perform checks either before or after 3250 // the VM performs its own checks. Naturally, the user code would be making 3251 // a serious error if it tried to handle an exception (such as a null check 3252 // or breakpoint) that the VM was generating for its own correct operation. 3253 // 3254 // This routine may recognize any of the following kinds of signals: 3255 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1. 3256 // It should be consulted by handlers for any of those signals. 3257 // 3258 // The caller of this routine must pass in the three arguments supplied 3259 // to the function referred to in the "sa_sigaction" (not the "sa_handler") 3260 // field of the structure passed to sigaction(). This routine assumes that 3261 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART. 3262 // 3263 // Note that the VM will print warnings if it detects conflicting signal 3264 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers". 3265 // 3266 extern "C" int 3267 JVM_handle_linux_signal(int signo, siginfo_t* siginfo, 3268 void* ucontext, int abort_if_unrecognized); 3269 3270 void signalHandler(int sig, siginfo_t* info, void* uc) { 3271 assert(info != NULL && uc != NULL, "it must be old kernel"); 3272 JVM_handle_linux_signal(sig, info, uc, true); 3273 } 3274 3275 3276 // This boolean allows users to forward their own non-matching signals 3277 // to JVM_handle_linux_signal, harmlessly. 3278 bool os::Linux::signal_handlers_are_installed = false; 3279 3280 // For signal-chaining 3281 struct sigaction os::Linux::sigact[MAXSIGNUM]; 3282 unsigned int os::Linux::sigs = 0; 3283 bool os::Linux::libjsig_is_loaded = false; 3284 typedef struct sigaction *(*get_signal_t)(int); 3285 get_signal_t os::Linux::get_signal_action = NULL; 3286 3287 struct sigaction* os::Linux::get_chained_signal_action(int sig) { 3288 struct sigaction *actp = NULL; 3289 3290 if (libjsig_is_loaded) { 3291 // Retrieve the old signal handler from libjsig 3292 actp = (*get_signal_action)(sig); 3293 } 3294 if (actp == NULL) { 3295 // Retrieve the preinstalled signal handler from jvm 3296 actp = get_preinstalled_handler(sig); 3297 } 3298 3299 return actp; 3300 } 3301 3302 static bool call_chained_handler(struct sigaction *actp, int sig, 3303 siginfo_t *siginfo, void *context) { 3304 // Call the old signal handler 3305 if (actp->sa_handler == SIG_DFL) { 3306 // It's more reasonable to let jvm treat it as an unexpected exception 3307 // instead of taking the default action. 3308 return false; 3309 } else if (actp->sa_handler != SIG_IGN) { 3310 if ((actp->sa_flags & SA_NODEFER) == 0) { 3311 // automaticlly block the signal 3312 sigaddset(&(actp->sa_mask), sig); 3313 } 3314 3315 sa_handler_t hand; 3316 sa_sigaction_t sa; 3317 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0; 3318 // retrieve the chained handler 3319 if (siginfo_flag_set) { 3320 sa = actp->sa_sigaction; 3321 } else { 3322 hand = actp->sa_handler; 3323 } 3324 3325 if ((actp->sa_flags & SA_RESETHAND) != 0) { 3326 actp->sa_handler = SIG_DFL; 3327 } 3328 3329 // try to honor the signal mask 3330 sigset_t oset; 3331 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset); 3332 3333 // call into the chained handler 3334 if (siginfo_flag_set) { 3335 (*sa)(sig, siginfo, context); 3336 } else { 3337 (*hand)(sig); 3338 } 3339 3340 // restore the signal mask 3341 pthread_sigmask(SIG_SETMASK, &oset, 0); 3342 } 3343 // Tell jvm's signal handler the signal is taken care of. 3344 return true; 3345 } 3346 3347 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) { 3348 bool chained = false; 3349 // signal-chaining 3350 if (UseSignalChaining) { 3351 struct sigaction *actp = get_chained_signal_action(sig); 3352 if (actp != NULL) { 3353 chained = call_chained_handler(actp, sig, siginfo, context); 3354 } 3355 } 3356 return chained; 3357 } 3358 3359 struct sigaction* os::Linux::get_preinstalled_handler(int sig) { 3360 if ((( (unsigned int)1 << sig ) & sigs) != 0) { 3361 return &sigact[sig]; 3362 } 3363 return NULL; 3364 } 3365 3366 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) { 3367 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3368 sigact[sig] = oldAct; 3369 sigs |= (unsigned int)1 << sig; 3370 } 3371 3372 // for diagnostic 3373 int os::Linux::sigflags[MAXSIGNUM]; 3374 3375 int os::Linux::get_our_sigflags(int sig) { 3376 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3377 return sigflags[sig]; 3378 } 3379 3380 void os::Linux::set_our_sigflags(int sig, int flags) { 3381 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3382 sigflags[sig] = flags; 3383 } 3384 3385 void os::Linux::set_signal_handler(int sig, bool set_installed) { 3386 // Check for overwrite. 3387 struct sigaction oldAct; 3388 sigaction(sig, (struct sigaction*)NULL, &oldAct); 3389 3390 void* oldhand = oldAct.sa_sigaction 3391 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3392 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3393 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) && 3394 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) && 3395 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) { 3396 if (AllowUserSignalHandlers || !set_installed) { 3397 // Do not overwrite; user takes responsibility to forward to us. 3398 return; 3399 } else if (UseSignalChaining) { 3400 // save the old handler in jvm 3401 save_preinstalled_handler(sig, oldAct); 3402 // libjsig also interposes the sigaction() call below and saves the 3403 // old sigaction on it own. 3404 } else { 3405 fatal2("Encountered unexpected pre-existing sigaction handler %#lx for signal %d.", (long)oldhand, sig); 3406 } 3407 } 3408 3409 struct sigaction sigAct; 3410 sigfillset(&(sigAct.sa_mask)); 3411 sigAct.sa_handler = SIG_DFL; 3412 if (!set_installed) { 3413 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3414 } else { 3415 sigAct.sa_sigaction = signalHandler; 3416 sigAct.sa_flags = SA_SIGINFO|SA_RESTART; 3417 } 3418 // Save flags, which are set by ours 3419 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); 3420 sigflags[sig] = sigAct.sa_flags; 3421 3422 int ret = sigaction(sig, &sigAct, &oldAct); 3423 assert(ret == 0, "check"); 3424 3425 void* oldhand2 = oldAct.sa_sigaction 3426 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction) 3427 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler); 3428 assert(oldhand2 == oldhand, "no concurrent signal handler installation"); 3429 } 3430 3431 // install signal handlers for signals that HotSpot needs to 3432 // handle in order to support Java-level exception handling. 3433 3434 void os::Linux::install_signal_handlers() { 3435 if (!signal_handlers_are_installed) { 3436 signal_handlers_are_installed = true; 3437 3438 // signal-chaining 3439 typedef void (*signal_setting_t)(); 3440 signal_setting_t begin_signal_setting = NULL; 3441 signal_setting_t end_signal_setting = NULL; 3442 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3443 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting")); 3444 if (begin_signal_setting != NULL) { 3445 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t, 3446 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting")); 3447 get_signal_action = CAST_TO_FN_PTR(get_signal_t, 3448 dlsym(RTLD_DEFAULT, "JVM_get_signal_action")); 3449 libjsig_is_loaded = true; 3450 assert(UseSignalChaining, "should enable signal-chaining"); 3451 } 3452 if (libjsig_is_loaded) { 3453 // Tell libjsig jvm is setting signal handlers 3454 (*begin_signal_setting)(); 3455 } 3456 3457 set_signal_handler(SIGSEGV, true); 3458 set_signal_handler(SIGPIPE, true); 3459 set_signal_handler(SIGBUS, true); 3460 set_signal_handler(SIGILL, true); 3461 set_signal_handler(SIGFPE, true); 3462 set_signal_handler(SIGXFSZ, true); 3463 3464 if (libjsig_is_loaded) { 3465 // Tell libjsig jvm finishes setting signal handlers 3466 (*end_signal_setting)(); 3467 } 3468 3469 // We don't activate signal checker if libjsig is in place, we trust ourselves 3470 // and if UserSignalHandler is installed all bets are off 3471 if (CheckJNICalls) { 3472 if (libjsig_is_loaded) { 3473 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); 3474 check_signals = false; 3475 } 3476 if (AllowUserSignalHandlers) { 3477 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); 3478 check_signals = false; 3479 } 3480 } 3481 } 3482 } 3483 3484 // This is the fastest way to get thread cpu time on Linux. 3485 // Returns cpu time (user+sys) for any thread, not only for current. 3486 // POSIX compliant clocks are implemented in the kernels 2.6.16+. 3487 // It might work on 2.6.10+ with a special kernel/glibc patch. 3488 // For reference, please, see IEEE Std 1003.1-2004: 3489 // http://www.unix.org/single_unix_specification 3490 3491 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { 3492 struct timespec tp; 3493 int rc = os::Linux::clock_gettime(clockid, &tp); 3494 assert(rc == 0, "clock_gettime is expected to return 0 code"); 3495 3496 return (tp.tv_sec * SEC_IN_NANOSECS) + tp.tv_nsec; 3497 } 3498 3499 ///// 3500 // glibc on Linux platform uses non-documented flag 3501 // to indicate, that some special sort of signal 3502 // trampoline is used. 3503 // We will never set this flag, and we should 3504 // ignore this flag in our diagnostic 3505 #ifdef SIGNIFICANT_SIGNAL_MASK 3506 #undef SIGNIFICANT_SIGNAL_MASK 3507 #endif 3508 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000) 3509 3510 static const char* get_signal_handler_name(address handler, 3511 char* buf, int buflen) { 3512 int offset; 3513 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset); 3514 if (found) { 3515 // skip directory names 3516 const char *p1, *p2; 3517 p1 = buf; 3518 size_t len = strlen(os::file_separator()); 3519 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len; 3520 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset); 3521 } else { 3522 jio_snprintf(buf, buflen, PTR_FORMAT, handler); 3523 } 3524 return buf; 3525 } 3526 3527 static void print_signal_handler(outputStream* st, int sig, 3528 char* buf, size_t buflen) { 3529 struct sigaction sa; 3530 3531 sigaction(sig, NULL, &sa); 3532 3533 // See comment for SIGNIFICANT_SIGNAL_MASK define 3534 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 3535 3536 st->print("%s: ", os::exception_name(sig, buf, buflen)); 3537 3538 address handler = (sa.sa_flags & SA_SIGINFO) 3539 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction) 3540 : CAST_FROM_FN_PTR(address, sa.sa_handler); 3541 3542 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) { 3543 st->print("SIG_DFL"); 3544 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) { 3545 st->print("SIG_IGN"); 3546 } else { 3547 st->print("[%s]", get_signal_handler_name(handler, buf, buflen)); 3548 } 3549 3550 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask); 3551 3552 address rh = VMError::get_resetted_sighandler(sig); 3553 // May be, handler was resetted by VMError? 3554 if(rh != NULL) { 3555 handler = rh; 3556 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK; 3557 } 3558 3559 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags); 3560 3561 // Check: is it our handler? 3562 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) || 3563 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) { 3564 // It is our signal handler 3565 // check for flags, reset system-used one! 3566 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) { 3567 st->print( 3568 ", flags was changed from " PTR32_FORMAT ", consider using jsig library", 3569 os::Linux::get_our_sigflags(sig)); 3570 } 3571 } 3572 st->cr(); 3573 } 3574 3575 3576 #define DO_SIGNAL_CHECK(sig) \ 3577 if (!sigismember(&check_signal_done, sig)) \ 3578 os::Linux::check_signal_handler(sig) 3579 3580 // This method is a periodic task to check for misbehaving JNI applications 3581 // under CheckJNI, we can add any periodic checks here 3582 3583 void os::run_periodic_checks() { 3584 3585 if (check_signals == false) return; 3586 3587 // SEGV and BUS if overridden could potentially prevent 3588 // generation of hs*.log in the event of a crash, debugging 3589 // such a case can be very challenging, so we absolutely 3590 // check the following for a good measure: 3591 DO_SIGNAL_CHECK(SIGSEGV); 3592 DO_SIGNAL_CHECK(SIGILL); 3593 DO_SIGNAL_CHECK(SIGFPE); 3594 DO_SIGNAL_CHECK(SIGBUS); 3595 DO_SIGNAL_CHECK(SIGPIPE); 3596 DO_SIGNAL_CHECK(SIGXFSZ); 3597 3598 3599 // ReduceSignalUsage allows the user to override these handlers 3600 // see comments at the very top and jvm_solaris.h 3601 if (!ReduceSignalUsage) { 3602 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL); 3603 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL); 3604 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL); 3605 DO_SIGNAL_CHECK(BREAK_SIGNAL); 3606 } 3607 3608 DO_SIGNAL_CHECK(SR_signum); 3609 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL); 3610 } 3611 3612 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *); 3613 3614 static os_sigaction_t os_sigaction = NULL; 3615 3616 void os::Linux::check_signal_handler(int sig) { 3617 char buf[O_BUFLEN]; 3618 address jvmHandler = NULL; 3619 3620 3621 struct sigaction act; 3622 if (os_sigaction == NULL) { 3623 // only trust the default sigaction, in case it has been interposed 3624 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction"); 3625 if (os_sigaction == NULL) return; 3626 } 3627 3628 os_sigaction(sig, (struct sigaction*)NULL, &act); 3629 3630 3631 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK; 3632 3633 address thisHandler = (act.sa_flags & SA_SIGINFO) 3634 ? CAST_FROM_FN_PTR(address, act.sa_sigaction) 3635 : CAST_FROM_FN_PTR(address, act.sa_handler) ; 3636 3637 3638 switch(sig) { 3639 case SIGSEGV: 3640 case SIGBUS: 3641 case SIGFPE: 3642 case SIGPIPE: 3643 case SIGILL: 3644 case SIGXFSZ: 3645 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler); 3646 break; 3647 3648 case SHUTDOWN1_SIGNAL: 3649 case SHUTDOWN2_SIGNAL: 3650 case SHUTDOWN3_SIGNAL: 3651 case BREAK_SIGNAL: 3652 jvmHandler = (address)user_handler(); 3653 break; 3654 3655 case INTERRUPT_SIGNAL: 3656 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL); 3657 break; 3658 3659 default: 3660 if (sig == SR_signum) { 3661 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler); 3662 } else { 3663 return; 3664 } 3665 break; 3666 } 3667 3668 if (thisHandler != jvmHandler) { 3669 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN)); 3670 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN)); 3671 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN)); 3672 // No need to check this sig any longer 3673 sigaddset(&check_signal_done, sig); 3674 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { 3675 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); 3676 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig)); 3677 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags); 3678 // No need to check this sig any longer 3679 sigaddset(&check_signal_done, sig); 3680 } 3681 3682 // Dump all the signal 3683 if (sigismember(&check_signal_done, sig)) { 3684 print_signal_handlers(tty, buf, O_BUFLEN); 3685 } 3686 } 3687 3688 extern void report_error(char* file_name, int line_no, char* title, char* format, ...); 3689 3690 extern bool signal_name(int signo, char* buf, size_t len); 3691 3692 const char* os::exception_name(int exception_code, char* buf, size_t size) { 3693 if (0 < exception_code && exception_code <= SIGRTMAX) { 3694 // signal 3695 if (!signal_name(exception_code, buf, size)) { 3696 jio_snprintf(buf, size, "SIG%d", exception_code); 3697 } 3698 return buf; 3699 } else { 3700 return NULL; 3701 } 3702 } 3703 3704 // this is called _before_ the most of global arguments have been parsed 3705 void os::init(void) { 3706 char dummy; /* used to get a guess on initial stack address */ 3707 // first_hrtime = gethrtime(); 3708 3709 // With LinuxThreads the JavaMain thread pid (primordial thread) 3710 // is different than the pid of the java launcher thread. 3711 // So, on Linux, the launcher thread pid is passed to the VM 3712 // via the sun.java.launcher.pid property. 3713 // Use this property instead of getpid() if it was correctly passed. 3714 // See bug 6351349. 3715 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid(); 3716 3717 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid(); 3718 3719 clock_tics_per_sec = sysconf(_SC_CLK_TCK); 3720 3721 init_random(1234567); 3722 3723 ThreadCritical::initialize(); 3724 3725 Linux::set_page_size(sysconf(_SC_PAGESIZE)); 3726 if (Linux::page_size() == -1) { 3727 fatal1("os_linux.cpp: os::init: sysconf failed (%s)", strerror(errno)); 3728 } 3729 init_page_sizes((size_t) Linux::page_size()); 3730 3731 Linux::initialize_system_info(); 3732 3733 // main_thread points to the aboriginal thread 3734 Linux::_main_thread = pthread_self(); 3735 3736 Linux::clock_init(); 3737 initial_time_count = os::elapsed_counter(); 3738 pthread_mutex_init(&dl_mutex, NULL); 3739 } 3740 3741 // To install functions for atexit system call 3742 extern "C" { 3743 static void perfMemory_exit_helper() { 3744 perfMemory_exit(); 3745 } 3746 } 3747 3748 // this is called _after_ the global arguments have been parsed 3749 jint os::init_2(void) 3750 { 3751 Linux::fast_thread_clock_init(); 3752 3753 // Allocate a single page and mark it as readable for safepoint polling 3754 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 3755 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" ); 3756 3757 os::set_polling_page( polling_page ); 3758 3759 #ifndef PRODUCT 3760 if(Verbose && PrintMiscellaneous) 3761 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page); 3762 #endif 3763 3764 if (!UseMembar) { 3765 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 3766 guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page"); 3767 os::set_memory_serialize_page( mem_serialize_page ); 3768 3769 #ifndef PRODUCT 3770 if(Verbose && PrintMiscellaneous) 3771 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page); 3772 #endif 3773 } 3774 3775 FLAG_SET_DEFAULT(UseLargePages, os::large_page_init()); 3776 3777 // initialize suspend/resume support - must do this before signal_sets_init() 3778 if (SR_initialize() != 0) { 3779 perror("SR_initialize failed"); 3780 return JNI_ERR; 3781 } 3782 3783 Linux::signal_sets_init(); 3784 Linux::install_signal_handlers(); 3785 3786 size_t threadStackSizeInBytes = ThreadStackSize * K; 3787 if (threadStackSizeInBytes != 0 && 3788 threadStackSizeInBytes < Linux::min_stack_allowed) { 3789 tty->print_cr("\nThe stack size specified is too small, " 3790 "Specify at least %dk", 3791 Linux::min_stack_allowed / K); 3792 return JNI_ERR; 3793 } 3794 3795 // Make the stack size a multiple of the page size so that 3796 // the yellow/red zones can be guarded. 3797 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes, 3798 vm_page_size())); 3799 3800 Linux::capture_initial_stack(JavaThread::stack_size_at_create()); 3801 3802 Linux::libpthread_init(); 3803 if (PrintMiscellaneous && (Verbose || WizardMode)) { 3804 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", 3805 Linux::glibc_version(), Linux::libpthread_version(), 3806 Linux::is_floating_stack() ? "floating stack" : "fixed stack"); 3807 } 3808 3809 if (UseNUMA) { 3810 if (!Linux::libnuma_init()) { 3811 UseNUMA = false; 3812 } else { 3813 if ((Linux::numa_max_node() < 1)) { 3814 // There's only one node(they start from 0), disable NUMA. 3815 UseNUMA = false; 3816 } 3817 } 3818 if (!UseNUMA && ForceNUMA) { 3819 UseNUMA = true; 3820 } 3821 } 3822 3823 if (MaxFDLimit) { 3824 // set the number of file descriptors to max. print out error 3825 // if getrlimit/setrlimit fails but continue regardless. 3826 struct rlimit nbr_files; 3827 int status = getrlimit(RLIMIT_NOFILE, &nbr_files); 3828 if (status != 0) { 3829 if (PrintMiscellaneous && (Verbose || WizardMode)) 3830 perror("os::init_2 getrlimit failed"); 3831 } else { 3832 nbr_files.rlim_cur = nbr_files.rlim_max; 3833 status = setrlimit(RLIMIT_NOFILE, &nbr_files); 3834 if (status != 0) { 3835 if (PrintMiscellaneous && (Verbose || WizardMode)) 3836 perror("os::init_2 setrlimit failed"); 3837 } 3838 } 3839 } 3840 3841 // Initialize lock used to serialize thread creation (see os::create_thread) 3842 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); 3843 3844 // Initialize HPI. 3845 jint hpi_result = hpi::initialize(); 3846 if (hpi_result != JNI_OK) { 3847 tty->print_cr("There was an error trying to initialize the HPI library."); 3848 return hpi_result; 3849 } 3850 3851 // at-exit methods are called in the reverse order of their registration. 3852 // atexit functions are called on return from main or as a result of a 3853 // call to exit(3C). There can be only 32 of these functions registered 3854 // and atexit() does not set errno. 3855 3856 if (PerfAllowAtExitRegistration) { 3857 // only register atexit functions if PerfAllowAtExitRegistration is set. 3858 // atexit functions can be delayed until process exit time, which 3859 // can be problematic for embedded VM situations. Embedded VMs should 3860 // call DestroyJavaVM() to assure that VM resources are released. 3861 3862 // note: perfMemory_exit_helper atexit function may be removed in 3863 // the future if the appropriate cleanup code can be added to the 3864 // VM_Exit VMOperation's doit method. 3865 if (atexit(perfMemory_exit_helper) != 0) { 3866 warning("os::init2 atexit(perfMemory_exit_helper) failed"); 3867 } 3868 } 3869 3870 // initialize thread priority policy 3871 prio_init(); 3872 3873 return JNI_OK; 3874 } 3875 3876 // Mark the polling page as unreadable 3877 void os::make_polling_page_unreadable(void) { 3878 if( !guard_memory((char*)_polling_page, Linux::page_size()) ) 3879 fatal("Could not disable polling page"); 3880 }; 3881 3882 // Mark the polling page as readable 3883 void os::make_polling_page_readable(void) { 3884 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { 3885 fatal("Could not enable polling page"); 3886 } 3887 }; 3888 3889 int os::active_processor_count() { 3890 // Linux doesn't yet have a (official) notion of processor sets, 3891 // so just return the number of online processors. 3892 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); 3893 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); 3894 return online_cpus; 3895 } 3896 3897 bool os::distribute_processes(uint length, uint* distribution) { 3898 // Not yet implemented. 3899 return false; 3900 } 3901 3902 bool os::bind_to_processor(uint processor_id) { 3903 // Not yet implemented. 3904 return false; 3905 } 3906 3907 /// 3908 3909 // Suspends the target using the signal mechanism and then grabs the PC before 3910 // resuming the target. Used by the flat-profiler only 3911 ExtendedPC os::get_thread_pc(Thread* thread) { 3912 // Make sure that it is called by the watcher for the VMThread 3913 assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); 3914 assert(thread->is_VM_thread(), "Can only be called for VMThread"); 3915 3916 ExtendedPC epc; 3917 3918 OSThread* osthread = thread->osthread(); 3919 if (do_suspend(osthread)) { 3920 if (osthread->ucontext() != NULL) { 3921 epc = os::Linux::ucontext_get_pc(osthread->ucontext()); 3922 } else { 3923 // NULL context is unexpected, double-check this is the VMThread 3924 guarantee(thread->is_VM_thread(), "can only be called for VMThread"); 3925 } 3926 do_resume(osthread); 3927 } 3928 // failure means pthread_kill failed for some reason - arguably this is 3929 // a fatal problem, but such problems are ignored elsewhere 3930 3931 return epc; 3932 } 3933 3934 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) 3935 { 3936 if (is_NPTL()) { 3937 return pthread_cond_timedwait(_cond, _mutex, _abstime); 3938 } else { 3939 #ifndef IA64 3940 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control 3941 // word back to default 64bit precision if condvar is signaled. Java 3942 // wants 53bit precision. Save and restore current value. 3943 int fpu = get_fpu_control_word(); 3944 #endif // IA64 3945 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); 3946 #ifndef IA64 3947 set_fpu_control_word(fpu); 3948 #endif // IA64 3949 return status; 3950 } 3951 } 3952 3953 //////////////////////////////////////////////////////////////////////////////// 3954 // debug support 3955 3956 #ifndef PRODUCT 3957 static address same_page(address x, address y) { 3958 int page_bits = -os::vm_page_size(); 3959 if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits)) 3960 return x; 3961 else if (x > y) 3962 return (address)(intptr_t(y) | ~page_bits) + 1; 3963 else 3964 return (address)(intptr_t(y) & page_bits); 3965 } 3966 3967 bool os::find(address addr) { 3968 Dl_info dlinfo; 3969 memset(&dlinfo, 0, sizeof(dlinfo)); 3970 if (dladdr(addr, &dlinfo)) { 3971 tty->print(PTR_FORMAT ": ", addr); 3972 if (dlinfo.dli_sname != NULL) { 3973 tty->print("%s+%#x", dlinfo.dli_sname, 3974 addr - (intptr_t)dlinfo.dli_saddr); 3975 } else if (dlinfo.dli_fname) { 3976 tty->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); 3977 } else { 3978 tty->print("<absolute address>"); 3979 } 3980 if (dlinfo.dli_fname) { 3981 tty->print(" in %s", dlinfo.dli_fname); 3982 } 3983 if (dlinfo.dli_fbase) { 3984 tty->print(" at " PTR_FORMAT, dlinfo.dli_fbase); 3985 } 3986 tty->cr(); 3987 3988 if (Verbose) { 3989 // decode some bytes around the PC 3990 address begin = same_page(addr-40, addr); 3991 address end = same_page(addr+40, addr); 3992 address lowest = (address) dlinfo.dli_sname; 3993 if (!lowest) lowest = (address) dlinfo.dli_fbase; 3994 if (begin < lowest) begin = lowest; 3995 Dl_info dlinfo2; 3996 if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr 3997 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) 3998 end = (address) dlinfo2.dli_saddr; 3999 Disassembler::decode(begin, end); 4000 } 4001 return true; 4002 } 4003 return false; 4004 } 4005 4006 #endif 4007 4008 //////////////////////////////////////////////////////////////////////////////// 4009 // misc 4010 4011 // This does not do anything on Linux. This is basically a hook for being 4012 // able to use structured exception handling (thread-local exception filters) 4013 // on, e.g., Win32. 4014 void 4015 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, 4016 JavaCallArguments* args, Thread* thread) { 4017 f(value, method, args, thread); 4018 } 4019 4020 void os::print_statistics() { 4021 } 4022 4023 int os::message_box(const char* title, const char* message) { 4024 int i; 4025 fdStream err(defaultStream::error_fd()); 4026 for (i = 0; i < 78; i++) err.print_raw("="); 4027 err.cr(); 4028 err.print_raw_cr(title); 4029 for (i = 0; i < 78; i++) err.print_raw("-"); 4030 err.cr(); 4031 err.print_raw_cr(message); 4032 for (i = 0; i < 78; i++) err.print_raw("="); 4033 err.cr(); 4034 4035 char buf[16]; 4036 // Prevent process from exiting upon "read error" without consuming all CPU 4037 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } 4038 4039 return buf[0] == 'y' || buf[0] == 'Y'; 4040 } 4041 4042 int os::stat(const char *path, struct stat *sbuf) { 4043 char pathbuf[MAX_PATH]; 4044 if (strlen(path) > MAX_PATH - 1) { 4045 errno = ENAMETOOLONG; 4046 return -1; 4047 } 4048 hpi::native_path(strcpy(pathbuf, path)); 4049 return ::stat(pathbuf, sbuf); 4050 } 4051 4052 bool os::check_heap(bool force) { 4053 return true; 4054 } 4055 4056 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) { 4057 return ::vsnprintf(buf, count, format, args); 4058 } 4059 4060 // Is a (classpath) directory empty? 4061 bool os::dir_is_empty(const char* path) { 4062 DIR *dir = NULL; 4063 struct dirent *ptr; 4064 4065 dir = opendir(path); 4066 if (dir == NULL) return true; 4067 4068 /* Scan the directory */ 4069 bool result = true; 4070 char buf[sizeof(struct dirent) + MAX_PATH]; 4071 while (result && (ptr = ::readdir(dir)) != NULL) { 4072 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { 4073 result = false; 4074 } 4075 } 4076 closedir(dir); 4077 return result; 4078 } 4079 4080 // create binary file, rewriting existing file if required 4081 int os::create_binary_file(const char* path, bool rewrite_existing) { 4082 int oflags = O_WRONLY | O_CREAT; 4083 if (!rewrite_existing) { 4084 oflags |= O_EXCL; 4085 } 4086 return ::open64(path, oflags, S_IREAD | S_IWRITE); 4087 } 4088 4089 // return current position of file pointer 4090 jlong os::current_file_offset(int fd) { 4091 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); 4092 } 4093 4094 // move file pointer to the specified offset 4095 jlong os::seek_to_file_offset(int fd, jlong offset) { 4096 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); 4097 } 4098 4099 // Map a block of memory. 4100 char* os::map_memory(int fd, const char* file_name, size_t file_offset, 4101 char *addr, size_t bytes, bool read_only, 4102 bool allow_exec) { 4103 int prot; 4104 int flags; 4105 4106 if (read_only) { 4107 prot = PROT_READ; 4108 flags = MAP_SHARED; 4109 } else { 4110 prot = PROT_READ | PROT_WRITE; 4111 flags = MAP_PRIVATE; 4112 } 4113 4114 if (allow_exec) { 4115 prot |= PROT_EXEC; 4116 } 4117 4118 if (addr != NULL) { 4119 flags |= MAP_FIXED; 4120 } 4121 4122 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, 4123 fd, file_offset); 4124 if (mapped_address == MAP_FAILED) { 4125 return NULL; 4126 } 4127 return mapped_address; 4128 } 4129 4130 4131 // Remap a block of memory. 4132 char* os::remap_memory(int fd, const char* file_name, size_t file_offset, 4133 char *addr, size_t bytes, bool read_only, 4134 bool allow_exec) { 4135 // same as map_memory() on this OS 4136 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only, 4137 allow_exec); 4138 } 4139 4140 4141 // Unmap a block of memory. 4142 bool os::unmap_memory(char* addr, size_t bytes) { 4143 return munmap(addr, bytes) == 0; 4144 } 4145 4146 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); 4147 4148 static clockid_t thread_cpu_clockid(Thread* thread) { 4149 pthread_t tid = thread->osthread()->pthread_id(); 4150 clockid_t clockid; 4151 4152 // Get thread clockid 4153 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); 4154 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); 4155 return clockid; 4156 } 4157 4158 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool) 4159 // are used by JVM M&M and JVMTI to get user+sys or user CPU time 4160 // of a thread. 4161 // 4162 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns 4163 // the fast estimate available on the platform. 4164 4165 jlong os::current_thread_cpu_time() { 4166 if (os::Linux::supports_fast_thread_cpu_time()) { 4167 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4168 } else { 4169 // return user + sys since the cost is the same 4170 return slow_thread_cpu_time(Thread::current(), true /* user + sys */); 4171 } 4172 } 4173 4174 jlong os::thread_cpu_time(Thread* thread) { 4175 // consistent with what current_thread_cpu_time() returns 4176 if (os::Linux::supports_fast_thread_cpu_time()) { 4177 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4178 } else { 4179 return slow_thread_cpu_time(thread, true /* user + sys */); 4180 } 4181 } 4182 4183 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { 4184 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4185 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); 4186 } else { 4187 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); 4188 } 4189 } 4190 4191 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4192 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { 4193 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); 4194 } else { 4195 return slow_thread_cpu_time(thread, user_sys_cpu_time); 4196 } 4197 } 4198 4199 // 4200 // -1 on error. 4201 // 4202 4203 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { 4204 static bool proc_pid_cpu_avail = true; 4205 static bool proc_task_unchecked = true; 4206 static const char *proc_stat_path = "/proc/%d/stat"; 4207 pid_t tid = thread->osthread()->thread_id(); 4208 int i; 4209 char *s; 4210 char stat[2048]; 4211 int statlen; 4212 char proc_name[64]; 4213 int count; 4214 long sys_time, user_time; 4215 char string[64]; 4216 int idummy; 4217 long ldummy; 4218 FILE *fp; 4219 4220 // We first try accessing /proc/<pid>/cpu since this is faster to 4221 // process. If this file is not present (linux kernels 2.5 and above) 4222 // then we open /proc/<pid>/stat. 4223 if ( proc_pid_cpu_avail ) { 4224 sprintf(proc_name, "/proc/%d/cpu", tid); 4225 fp = fopen(proc_name, "r"); 4226 if ( fp != NULL ) { 4227 count = fscanf( fp, "%s %lu %lu\n", string, &user_time, &sys_time); 4228 fclose(fp); 4229 if ( count != 3 ) return -1; 4230 4231 if (user_sys_cpu_time) { 4232 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 4233 } else { 4234 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 4235 } 4236 } 4237 else proc_pid_cpu_avail = false; 4238 } 4239 4240 // The /proc/<tid>/stat aggregates per-process usage on 4241 // new Linux kernels 2.6+ where NPTL is supported. 4242 // The /proc/self/task/<tid>/stat still has the per-thread usage. 4243 // See bug 6328462. 4244 // There can be no directory /proc/self/task on kernels 2.4 with NPTL 4245 // and possibly in some other cases, so we check its availability. 4246 if (proc_task_unchecked && os::Linux::is_NPTL()) { 4247 // This is executed only once 4248 proc_task_unchecked = false; 4249 fp = fopen("/proc/self/task", "r"); 4250 if (fp != NULL) { 4251 proc_stat_path = "/proc/self/task/%d/stat"; 4252 fclose(fp); 4253 } 4254 } 4255 4256 sprintf(proc_name, proc_stat_path, tid); 4257 fp = fopen(proc_name, "r"); 4258 if ( fp == NULL ) return -1; 4259 statlen = fread(stat, 1, 2047, fp); 4260 stat[statlen] = '\0'; 4261 fclose(fp); 4262 4263 // Skip pid and the command string. Note that we could be dealing with 4264 // weird command names, e.g. user could decide to rename java launcher 4265 // to "java 1.4.2 :)", then the stat file would look like 4266 // 1234 (java 1.4.2 :)) R ... ... 4267 // We don't really need to know the command string, just find the last 4268 // occurrence of ")" and then start parsing from there. See bug 4726580. 4269 s = strrchr(stat, ')'); 4270 i = 0; 4271 if (s == NULL ) return -1; 4272 4273 // Skip blank chars 4274 do s++; while (isspace(*s)); 4275 4276 count = sscanf(s,"%*c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", 4277 &idummy, &idummy, &idummy, &idummy, &idummy, 4278 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, 4279 &user_time, &sys_time); 4280 if ( count != 12 ) return -1; 4281 if (user_sys_cpu_time) { 4282 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); 4283 } else { 4284 return (jlong)user_time * (1000000000 / clock_tics_per_sec); 4285 } 4286 } 4287 4288 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4289 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4290 info_ptr->may_skip_backward = false; // elapsed time not wall time 4291 info_ptr->may_skip_forward = false; // elapsed time not wall time 4292 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4293 } 4294 4295 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) { 4296 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits 4297 info_ptr->may_skip_backward = false; // elapsed time not wall time 4298 info_ptr->may_skip_forward = false; // elapsed time not wall time 4299 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned 4300 } 4301 4302 bool os::is_thread_cpu_time_supported() { 4303 return true; 4304 } 4305 4306 // System loadavg support. Returns -1 if load average cannot be obtained. 4307 // Linux doesn't yet have a (official) notion of processor sets, 4308 // so just return the system wide load average. 4309 int os::loadavg(double loadavg[], int nelem) { 4310 return ::getloadavg(loadavg, nelem); 4311 } 4312 4313 void os::pause() { 4314 char filename[MAX_PATH]; 4315 if (PauseAtStartupFile && PauseAtStartupFile[0]) { 4316 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile); 4317 } else { 4318 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id()); 4319 } 4320 4321 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666); 4322 if (fd != -1) { 4323 struct stat buf; 4324 close(fd); 4325 while (::stat(filename, &buf) == 0) { 4326 (void)::poll(NULL, 0, 100); 4327 } 4328 } else { 4329 jio_fprintf(stderr, 4330 "Could not open pause file '%s', continuing immediately.\n", filename); 4331 } 4332 } 4333 4334 extern "C" { 4335 4336 /** 4337 * NOTE: the following code is to keep the green threads code 4338 * in the libjava.so happy. Once the green threads is removed, 4339 * these code will no longer be needed. 4340 */ 4341 int 4342 jdk_waitpid(pid_t pid, int* status, int options) { 4343 return waitpid(pid, status, options); 4344 } 4345 4346 int 4347 fork1() { 4348 return fork(); 4349 } 4350 4351 int 4352 jdk_sem_init(sem_t *sem, int pshared, unsigned int value) { 4353 return sem_init(sem, pshared, value); 4354 } 4355 4356 int 4357 jdk_sem_post(sem_t *sem) { 4358 return sem_post(sem); 4359 } 4360 4361 int 4362 jdk_sem_wait(sem_t *sem) { 4363 return sem_wait(sem); 4364 } 4365 4366 int 4367 jdk_pthread_sigmask(int how , const sigset_t* newmask, sigset_t* oldmask) { 4368 return pthread_sigmask(how , newmask, oldmask); 4369 } 4370 4371 } 4372 4373 // Refer to the comments in os_solaris.cpp park-unpark. 4374 // 4375 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can 4376 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable. 4377 // For specifics regarding the bug see GLIBC BUGID 261237 : 4378 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html. 4379 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future 4380 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar 4381 // is used. (The simple C test-case provided in the GLIBC bug report manifests the 4382 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos() 4383 // and monitorenter when we're using 1-0 locking. All those operations may result in 4384 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version 4385 // of libpthread avoids the problem, but isn't practical. 4386 // 4387 // Possible remedies: 4388 // 4389 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work. 4390 // This is palliative and probabilistic, however. If the thread is preempted 4391 // between the call to compute_abstime() and pthread_cond_timedwait(), more 4392 // than the minimum period may have passed, and the abstime may be stale (in the 4393 // past) resultin in a hang. Using this technique reduces the odds of a hang 4394 // but the JVM is still vulnerable, particularly on heavily loaded systems. 4395 // 4396 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead 4397 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set 4398 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo) 4399 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant 4400 // thread. 4401 // 4402 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread 4403 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing 4404 // a timeout request to the chron thread and then blocking via pthread_cond_wait(). 4405 // This also works well. In fact it avoids kernel-level scalability impediments 4406 // on certain platforms that don't handle lots of active pthread_cond_timedwait() 4407 // timers in a graceful fashion. 4408 // 4409 // 4. When the abstime value is in the past it appears that control returns 4410 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt. 4411 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we 4412 // can avoid the problem by reinitializing the condvar -- by cond_destroy() 4413 // followed by cond_init() -- after all calls to pthread_cond_timedwait(). 4414 // It may be possible to avoid reinitialization by checking the return 4415 // value from pthread_cond_timedwait(). In addition to reinitializing the 4416 // condvar we must establish the invariant that cond_signal() is only called 4417 // within critical sections protected by the adjunct mutex. This prevents 4418 // cond_signal() from "seeing" a condvar that's in the midst of being 4419 // reinitialized or that is corrupt. Sadly, this invariant obviates the 4420 // desirable signal-after-unlock optimization that avoids futile context switching. 4421 // 4422 // I'm also concerned that some versions of NTPL might allocate an auxilliary 4423 // structure when a condvar is used or initialized. cond_destroy() would 4424 // release the helper structure. Our reinitialize-after-timedwait fix 4425 // put excessive stress on malloc/free and locks protecting the c-heap. 4426 // 4427 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag. 4428 // It may be possible to refine (4) by checking the kernel and NTPL verisons 4429 // and only enabling the work-around for vulnerable environments. 4430 4431 // utility to compute the abstime argument to timedwait: 4432 // millis is the relative timeout time 4433 // abstime will be the absolute timeout time 4434 // TODO: replace compute_abstime() with unpackTime() 4435 4436 static struct timespec* compute_abstime(timespec* abstime, jlong millis) { 4437 if (millis < 0) millis = 0; 4438 struct timeval now; 4439 int status = gettimeofday(&now, NULL); 4440 assert(status == 0, "gettimeofday"); 4441 jlong seconds = millis / 1000; 4442 millis %= 1000; 4443 if (seconds > 50000000) { // see man cond_timedwait(3T) 4444 seconds = 50000000; 4445 } 4446 abstime->tv_sec = now.tv_sec + seconds; 4447 long usec = now.tv_usec + millis * 1000; 4448 if (usec >= 1000000) { 4449 abstime->tv_sec += 1; 4450 usec -= 1000000; 4451 } 4452 abstime->tv_nsec = usec * 1000; 4453 return abstime; 4454 } 4455 4456 4457 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately. 4458 // Conceptually TryPark() should be equivalent to park(0). 4459 4460 int os::PlatformEvent::TryPark() { 4461 for (;;) { 4462 const int v = _Event ; 4463 guarantee ((v == 0) || (v == 1), "invariant") ; 4464 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ; 4465 } 4466 } 4467 4468 void os::PlatformEvent::park() { // AKA "down()" 4469 // Invariant: Only the thread associated with the Event/PlatformEvent 4470 // may call park(). 4471 // TODO: assert that _Assoc != NULL or _Assoc == Self 4472 int v ; 4473 for (;;) { 4474 v = _Event ; 4475 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 4476 } 4477 guarantee (v >= 0, "invariant") ; 4478 if (v == 0) { 4479 // Do this the hard way by blocking ... 4480 int status = pthread_mutex_lock(_mutex); 4481 assert_status(status == 0, status, "mutex_lock"); 4482 guarantee (_nParked == 0, "invariant") ; 4483 ++ _nParked ; 4484 while (_Event < 0) { 4485 status = pthread_cond_wait(_cond, _mutex); 4486 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ... 4487 // Treat this the same as if the wait was interrupted 4488 if (status == ETIME) { status = EINTR; } 4489 assert_status(status == 0 || status == EINTR, status, "cond_wait"); 4490 } 4491 -- _nParked ; 4492 4493 // In theory we could move the ST of 0 into _Event past the unlock(), 4494 // but then we'd need a MEMBAR after the ST. 4495 _Event = 0 ; 4496 status = pthread_mutex_unlock(_mutex); 4497 assert_status(status == 0, status, "mutex_unlock"); 4498 } 4499 guarantee (_Event >= 0, "invariant") ; 4500 } 4501 4502 int os::PlatformEvent::park(jlong millis) { 4503 guarantee (_nParked == 0, "invariant") ; 4504 4505 int v ; 4506 for (;;) { 4507 v = _Event ; 4508 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ; 4509 } 4510 guarantee (v >= 0, "invariant") ; 4511 if (v != 0) return OS_OK ; 4512 4513 // We do this the hard way, by blocking the thread. 4514 // Consider enforcing a minimum timeout value. 4515 struct timespec abst; 4516 compute_abstime(&abst, millis); 4517 4518 int ret = OS_TIMEOUT; 4519 int status = pthread_mutex_lock(_mutex); 4520 assert_status(status == 0, status, "mutex_lock"); 4521 guarantee (_nParked == 0, "invariant") ; 4522 ++_nParked ; 4523 4524 // Object.wait(timo) will return because of 4525 // (a) notification 4526 // (b) timeout 4527 // (c) thread.interrupt 4528 // 4529 // Thread.interrupt and object.notify{All} both call Event::set. 4530 // That is, we treat thread.interrupt as a special case of notification. 4531 // The underlying Solaris implementation, cond_timedwait, admits 4532 // spurious/premature wakeups, but the JLS/JVM spec prevents the 4533 // JVM from making those visible to Java code. As such, we must 4534 // filter out spurious wakeups. We assume all ETIME returns are valid. 4535 // 4536 // TODO: properly differentiate simultaneous notify+interrupt. 4537 // In that case, we should propagate the notify to another waiter. 4538 4539 while (_Event < 0) { 4540 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst); 4541 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 4542 pthread_cond_destroy (_cond); 4543 pthread_cond_init (_cond, NULL) ; 4544 } 4545 assert_status(status == 0 || status == EINTR || 4546 status == ETIME || status == ETIMEDOUT, 4547 status, "cond_timedwait"); 4548 if (!FilterSpuriousWakeups) break ; // previous semantics 4549 if (status == ETIME || status == ETIMEDOUT) break ; 4550 // We consume and ignore EINTR and spurious wakeups. 4551 } 4552 --_nParked ; 4553 if (_Event >= 0) { 4554 ret = OS_OK; 4555 } 4556 _Event = 0 ; 4557 status = pthread_mutex_unlock(_mutex); 4558 assert_status(status == 0, status, "mutex_unlock"); 4559 assert (_nParked == 0, "invariant") ; 4560 return ret; 4561 } 4562 4563 void os::PlatformEvent::unpark() { 4564 int v, AnyWaiters ; 4565 for (;;) { 4566 v = _Event ; 4567 if (v > 0) { 4568 // The LD of _Event could have reordered or be satisfied 4569 // by a read-aside from this processor's write buffer. 4570 // To avoid problems execute a barrier and then 4571 // ratify the value. 4572 OrderAccess::fence() ; 4573 if (_Event == v) return ; 4574 continue ; 4575 } 4576 if (Atomic::cmpxchg (v+1, &_Event, v) == v) break ; 4577 } 4578 if (v < 0) { 4579 // Wait for the thread associated with the event to vacate 4580 int status = pthread_mutex_lock(_mutex); 4581 assert_status(status == 0, status, "mutex_lock"); 4582 AnyWaiters = _nParked ; 4583 assert (AnyWaiters == 0 || AnyWaiters == 1, "invariant") ; 4584 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) { 4585 AnyWaiters = 0 ; 4586 pthread_cond_signal (_cond); 4587 } 4588 status = pthread_mutex_unlock(_mutex); 4589 assert_status(status == 0, status, "mutex_unlock"); 4590 if (AnyWaiters != 0) { 4591 status = pthread_cond_signal(_cond); 4592 assert_status(status == 0, status, "cond_signal"); 4593 } 4594 } 4595 4596 // Note that we signal() _after dropping the lock for "immortal" Events. 4597 // This is safe and avoids a common class of futile wakeups. In rare 4598 // circumstances this can cause a thread to return prematurely from 4599 // cond_{timed}wait() but the spurious wakeup is benign and the victim will 4600 // simply re-test the condition and re-park itself. 4601 } 4602 4603 4604 // JSR166 4605 // ------------------------------------------------------- 4606 4607 /* 4608 * The solaris and linux implementations of park/unpark are fairly 4609 * conservative for now, but can be improved. They currently use a 4610 * mutex/condvar pair, plus a a count. 4611 * Park decrements count if > 0, else does a condvar wait. Unpark 4612 * sets count to 1 and signals condvar. Only one thread ever waits 4613 * on the condvar. Contention seen when trying to park implies that someone 4614 * is unparking you, so don't wait. And spurious returns are fine, so there 4615 * is no need to track notifications. 4616 */ 4617 4618 4619 #define NANOSECS_PER_SEC 1000000000 4620 #define NANOSECS_PER_MILLISEC 1000000 4621 #define MAX_SECS 100000000 4622 /* 4623 * This code is common to linux and solaris and will be moved to a 4624 * common place in dolphin. 4625 * 4626 * The passed in time value is either a relative time in nanoseconds 4627 * or an absolute time in milliseconds. Either way it has to be unpacked 4628 * into suitable seconds and nanoseconds components and stored in the 4629 * given timespec structure. 4630 * Given time is a 64-bit value and the time_t used in the timespec is only 4631 * a signed-32-bit value (except on 64-bit Linux) we have to watch for 4632 * overflow if times way in the future are given. Further on Solaris versions 4633 * prior to 10 there is a restriction (see cond_timedwait) that the specified 4634 * number of seconds, in abstime, is less than current_time + 100,000,000. 4635 * As it will be 28 years before "now + 100000000" will overflow we can 4636 * ignore overflow and just impose a hard-limit on seconds using the value 4637 * of "now + 100,000,000". This places a limit on the timeout of about 3.17 4638 * years from "now". 4639 */ 4640 4641 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) { 4642 assert (time > 0, "convertTime"); 4643 4644 struct timeval now; 4645 int status = gettimeofday(&now, NULL); 4646 assert(status == 0, "gettimeofday"); 4647 4648 time_t max_secs = now.tv_sec + MAX_SECS; 4649 4650 if (isAbsolute) { 4651 jlong secs = time / 1000; 4652 if (secs > max_secs) { 4653 absTime->tv_sec = max_secs; 4654 } 4655 else { 4656 absTime->tv_sec = secs; 4657 } 4658 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC; 4659 } 4660 else { 4661 jlong secs = time / NANOSECS_PER_SEC; 4662 if (secs >= MAX_SECS) { 4663 absTime->tv_sec = max_secs; 4664 absTime->tv_nsec = 0; 4665 } 4666 else { 4667 absTime->tv_sec = now.tv_sec + secs; 4668 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000; 4669 if (absTime->tv_nsec >= NANOSECS_PER_SEC) { 4670 absTime->tv_nsec -= NANOSECS_PER_SEC; 4671 ++absTime->tv_sec; // note: this must be <= max_secs 4672 } 4673 } 4674 } 4675 assert(absTime->tv_sec >= 0, "tv_sec < 0"); 4676 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs"); 4677 assert(absTime->tv_nsec >= 0, "tv_nsec < 0"); 4678 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec"); 4679 } 4680 4681 void Parker::park(bool isAbsolute, jlong time) { 4682 // Optional fast-path check: 4683 // Return immediately if a permit is available. 4684 if (_counter > 0) { 4685 _counter = 0 ; 4686 return ; 4687 } 4688 4689 Thread* thread = Thread::current(); 4690 assert(thread->is_Java_thread(), "Must be JavaThread"); 4691 JavaThread *jt = (JavaThread *)thread; 4692 4693 // Optional optimization -- avoid state transitions if there's an interrupt pending. 4694 // Check interrupt before trying to wait 4695 if (Thread::is_interrupted(thread, false)) { 4696 return; 4697 } 4698 4699 // Next, demultiplex/decode time arguments 4700 timespec absTime; 4701 if (time < 0) { // don't wait at all 4702 return; 4703 } 4704 if (time > 0) { 4705 unpackTime(&absTime, isAbsolute, time); 4706 } 4707 4708 4709 // Enter safepoint region 4710 // Beware of deadlocks such as 6317397. 4711 // The per-thread Parker:: mutex is a classic leaf-lock. 4712 // In particular a thread must never block on the Threads_lock while 4713 // holding the Parker:: mutex. If safepoints are pending both the 4714 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. 4715 ThreadBlockInVM tbivm(jt); 4716 4717 // Don't wait if cannot get lock since interference arises from 4718 // unblocking. Also. check interrupt before trying wait 4719 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) { 4720 return; 4721 } 4722 4723 int status ; 4724 if (_counter > 0) { // no wait needed 4725 _counter = 0; 4726 status = pthread_mutex_unlock(_mutex); 4727 assert (status == 0, "invariant") ; 4728 return; 4729 } 4730 4731 #ifdef ASSERT 4732 // Don't catch signals while blocked; let the running threads have the signals. 4733 // (This allows a debugger to break into the running thread.) 4734 sigset_t oldsigs; 4735 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals(); 4736 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs); 4737 #endif 4738 4739 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */); 4740 jt->set_suspend_equivalent(); 4741 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self() 4742 4743 if (time == 0) { 4744 status = pthread_cond_wait (_cond, _mutex) ; 4745 } else { 4746 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ; 4747 if (status != 0 && WorkAroundNPTLTimedWaitHang) { 4748 pthread_cond_destroy (_cond) ; 4749 pthread_cond_init (_cond, NULL); 4750 } 4751 } 4752 assert_status(status == 0 || status == EINTR || 4753 status == ETIME || status == ETIMEDOUT, 4754 status, "cond_timedwait"); 4755 4756 #ifdef ASSERT 4757 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); 4758 #endif 4759 4760 _counter = 0 ; 4761 status = pthread_mutex_unlock(_mutex) ; 4762 assert_status(status == 0, status, "invariant") ; 4763 // If externally suspended while waiting, re-suspend 4764 if (jt->handle_special_suspend_equivalent_condition()) { 4765 jt->java_suspend_self(); 4766 } 4767 4768 } 4769 4770 void Parker::unpark() { 4771 int s, status ; 4772 status = pthread_mutex_lock(_mutex); 4773 assert (status == 0, "invariant") ; 4774 s = _counter; 4775 _counter = 1; 4776 if (s < 1) { 4777 if (WorkAroundNPTLTimedWaitHang) { 4778 status = pthread_cond_signal (_cond) ; 4779 assert (status == 0, "invariant") ; 4780 status = pthread_mutex_unlock(_mutex); 4781 assert (status == 0, "invariant") ; 4782 } else { 4783 status = pthread_mutex_unlock(_mutex); 4784 assert (status == 0, "invariant") ; 4785 status = pthread_cond_signal (_cond) ; 4786 assert (status == 0, "invariant") ; 4787 } 4788 } else { 4789 pthread_mutex_unlock(_mutex); 4790 assert (status == 0, "invariant") ; 4791 } 4792 } 4793 4794 4795 extern char** environ; 4796 4797 #ifndef __NR_fork 4798 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) 4799 #endif 4800 4801 #ifndef __NR_execve 4802 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) 4803 #endif 4804 4805 // Run the specified command in a separate process. Return its exit value, 4806 // or -1 on failure (e.g. can't fork a new process). 4807 // Unlike system(), this function can be called from signal handler. It 4808 // doesn't block SIGINT et al. 4809 int os::fork_and_exec(char* cmd) { 4810 const char * argv[4] = {"sh", "-c", cmd, NULL}; 4811 4812 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run 4813 // pthread_atfork handlers and reset pthread library. All we need is a 4814 // separate process to execve. Make a direct syscall to fork process. 4815 // On IA64 there's no fork syscall, we have to use fork() and hope for 4816 // the best... 4817 pid_t pid = NOT_IA64(syscall(__NR_fork);) 4818 IA64_ONLY(fork();) 4819 4820 if (pid < 0) { 4821 // fork failed 4822 return -1; 4823 4824 } else if (pid == 0) { 4825 // child process 4826 4827 // execve() in LinuxThreads will call pthread_kill_other_threads_np() 4828 // first to kill every thread on the thread list. Because this list is 4829 // not reset by fork() (see notes above), execve() will instead kill 4830 // every thread in the parent process. We know this is the only thread 4831 // in the new process, so make a system call directly. 4832 // IA64 should use normal execve() from glibc to match the glibc fork() 4833 // above. 4834 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) 4835 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);) 4836 4837 // execve failed 4838 _exit(-1); 4839 4840 } else { 4841 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't 4842 // care about the actual exit code, for now. 4843 4844 int status; 4845 4846 // Wait for the child process to exit. This returns immediately if 4847 // the child has already exited. */ 4848 while (waitpid(pid, &status, 0) < 0) { 4849 switch (errno) { 4850 case ECHILD: return 0; 4851 case EINTR: break; 4852 default: return -1; 4853 } 4854 } 4855 4856 if (WIFEXITED(status)) { 4857 // The child exited normally; get its exit code. 4858 return WEXITSTATUS(status); 4859 } else if (WIFSIGNALED(status)) { 4860 // The child exited because of a signal 4861 // The best value to return is 0x80 + signal number, 4862 // because that is what all Unix shells do, and because 4863 // it allows callers to distinguish between process exit and 4864 // process death by signal. 4865 return 0x80 + WTERMSIG(status); 4866 } else { 4867 // Unknown exit code; pass it through 4868 return status; 4869 } 4870 } 4871 }