1 /*
   2  * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 # define __STDC_FORMAT_MACROS
  26 
  27 // no precompiled headers
  28 #include "classfile/classLoader.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "code/icBuffer.hpp"
  32 #include "code/vtableStubs.hpp"
  33 #include "compiler/compileBroker.hpp"
  34 #include "interpreter/interpreter.hpp"
  35 #include "jvm_linux.h"
  36 #include "memory/allocation.inline.hpp"
  37 #include "memory/filemap.hpp"
  38 #include "mutex_linux.inline.hpp"
  39 #include "oops/oop.inline.hpp"
  40 #include "os_share_linux.hpp"
  41 #include "prims/jniFastGetField.hpp"
  42 #include "prims/jvm.h"
  43 #include "prims/jvm_misc.hpp"
  44 #include "runtime/arguments.hpp"
  45 #include "runtime/extendedPC.hpp"
  46 #include "runtime/globals.hpp"
  47 #include "runtime/interfaceSupport.hpp"
  48 #include "runtime/java.hpp"
  49 #include "runtime/javaCalls.hpp"
  50 #include "runtime/mutexLocker.hpp"
  51 #include "runtime/objectMonitor.hpp"
  52 #include "runtime/osThread.hpp"
  53 #include "runtime/perfMemory.hpp"
  54 #include "runtime/sharedRuntime.hpp"
  55 #include "runtime/statSampler.hpp"
  56 #include "runtime/stubRoutines.hpp"
  57 #include "runtime/threadCritical.hpp"
  58 #include "runtime/timer.hpp"
  59 #include "services/attachListener.hpp"
  60 #include "services/runtimeService.hpp"
  61 #include "thread_linux.inline.hpp"
  62 #include "utilities/decoder.hpp"
  63 #include "utilities/defaultStream.hpp"
  64 #include "utilities/events.hpp"
  65 #include "utilities/growableArray.hpp"
  66 #include "utilities/vmError.hpp"
  67 #ifdef TARGET_ARCH_x86
  68 # include "assembler_x86.inline.hpp"
  69 # include "nativeInst_x86.hpp"
  70 #endif
  71 #ifdef TARGET_ARCH_sparc
  72 # include "assembler_sparc.inline.hpp"
  73 # include "nativeInst_sparc.hpp"
  74 #endif
  75 #ifdef TARGET_ARCH_zero
  76 # include "assembler_zero.inline.hpp"
  77 # include "nativeInst_zero.hpp"
  78 #endif
  79 #ifdef TARGET_ARCH_arm
  80 # include "assembler_arm.inline.hpp"
  81 # include "nativeInst_arm.hpp"
  82 #endif
  83 #ifdef TARGET_ARCH_ppc
  84 # include "assembler_ppc.inline.hpp"
  85 # include "nativeInst_ppc.hpp"
  86 #endif
  87 #ifdef COMPILER1
  88 #include "c1/c1_Runtime1.hpp"
  89 #endif
  90 #ifdef COMPILER2
  91 #include "opto/runtime.hpp"
  92 #endif
  93 
  94 // put OS-includes here
  95 # include <sys/types.h>
  96 # include <sys/mman.h>
  97 # include <sys/stat.h>
  98 # include <sys/select.h>
  99 # include <pthread.h>
 100 # include <signal.h>
 101 # include <errno.h>
 102 # include <dlfcn.h>
 103 # include <stdio.h>
 104 # include <unistd.h>
 105 # include <sys/resource.h>
 106 # include <pthread.h>
 107 # include <sys/stat.h>
 108 # include <sys/time.h>
 109 # include <sys/times.h>
 110 # include <sys/utsname.h>
 111 # include <sys/socket.h>
 112 # include <sys/wait.h>
 113 # include <pwd.h>
 114 # include <poll.h>
 115 # include <semaphore.h>
 116 # include <fcntl.h>
 117 # include <string.h>
 118 # include <syscall.h>
 119 # include <sys/sysinfo.h>
 120 # include <gnu/libc-version.h>
 121 # include <sys/ipc.h>
 122 # include <sys/shm.h>
 123 # include <link.h>
 124 # include <stdint.h>
 125 # include <inttypes.h>
 126 # include <sys/ioctl.h>
 127 
 128 #define MAX_PATH    (2 * K)
 129 
 130 // for timer info max values which include all bits
 131 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
 132 #define SEC_IN_NANOSECS  1000000000LL
 133 
 134 #define LARGEPAGES_BIT (1 << 6)
 135 ////////////////////////////////////////////////////////////////////////////////
 136 // global variables
 137 julong os::Linux::_physical_memory = 0;
 138 
 139 address   os::Linux::_initial_thread_stack_bottom = NULL;
 140 uintptr_t os::Linux::_initial_thread_stack_size   = 0;
 141 
 142 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
 143 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
 144 Mutex* os::Linux::_createThread_lock = NULL;
 145 pthread_t os::Linux::_main_thread;
 146 int os::Linux::_page_size = -1;
 147 bool os::Linux::_is_floating_stack = false;
 148 bool os::Linux::_is_NPTL = false;
 149 bool os::Linux::_supports_fast_thread_cpu_time = false;
 150 const char * os::Linux::_glibc_version = NULL;
 151 const char * os::Linux::_libpthread_version = NULL;
 152 
 153 static jlong initial_time_count=0;
 154 
 155 static int clock_tics_per_sec = 100;
 156 
 157 // For diagnostics to print a message once. see run_periodic_checks
 158 static sigset_t check_signal_done;
 159 static bool check_signals = true;;
 160 
 161 static pid_t _initial_pid = 0;
 162 
 163 /* Signal number used to suspend/resume a thread */
 164 
 165 /* do not use any signal number less than SIGSEGV, see 4355769 */
 166 static int SR_signum = SIGUSR2;
 167 sigset_t SR_sigset;
 168 
 169 /* Used to protect dlsym() calls */
 170 static pthread_mutex_t dl_mutex;
 171 
 172 #ifdef JAVASE_EMBEDDED
 173 class MemNotifyThread: public Thread {
 174   friend class VMStructs;
 175  public:
 176   virtual void run();
 177 
 178  private:
 179   static MemNotifyThread* _memnotify_thread;
 180   int _fd;
 181 
 182  public:
 183 
 184   // Constructor
 185   MemNotifyThread(int fd);
 186 
 187   // Tester
 188   bool is_memnotify_thread() const { return true; }
 189 
 190   // Printing
 191   char* name() const { return (char*)"Linux MemNotify Thread"; }
 192 
 193   // Returns the single instance of the MemNotifyThread
 194   static MemNotifyThread* memnotify_thread() { return _memnotify_thread; }
 195 
 196   // Create and start the single instance of MemNotifyThread
 197   static void start();
 198 };
 199 #endif // JAVASE_EMBEDDED
 200 
 201 // utility functions
 202 
 203 static int SR_initialize();
 204 static int SR_finalize();
 205 
 206 julong os::available_memory() {
 207   return Linux::available_memory();
 208 }
 209 
 210 julong os::Linux::available_memory() {
 211   // values in struct sysinfo are "unsigned long"
 212   struct sysinfo si;
 213   sysinfo(&si);
 214 
 215   return (julong)si.freeram * si.mem_unit;
 216 }
 217 
 218 julong os::physical_memory() {
 219   return Linux::physical_memory();
 220 }
 221 
 222 julong os::allocatable_physical_memory(julong size) {
 223 #ifdef _LP64
 224   return size;
 225 #else
 226   julong result = MIN2(size, (julong)3800*M);
 227    if (!is_allocatable(result)) {
 228      // See comments under solaris for alignment considerations
 229      julong reasonable_size = (julong)2*G - 2 * os::vm_page_size();
 230      result =  MIN2(size, reasonable_size);
 231    }
 232    return result;
 233 #endif // _LP64
 234 }
 235 
 236 ////////////////////////////////////////////////////////////////////////////////
 237 // environment support
 238 
 239 bool os::getenv(const char* name, char* buf, int len) {
 240   const char* val = ::getenv(name);
 241   if (val != NULL && strlen(val) < (size_t)len) {
 242     strcpy(buf, val);
 243     return true;
 244   }
 245   if (len > 0) buf[0] = 0;  // return a null string
 246   return false;
 247 }
 248 
 249 
 250 // Return true if user is running as root.
 251 
 252 bool os::have_special_privileges() {
 253   static bool init = false;
 254   static bool privileges = false;
 255   if (!init) {
 256     privileges = (getuid() != geteuid()) || (getgid() != getegid());
 257     init = true;
 258   }
 259   return privileges;
 260 }
 261 
 262 
 263 #ifndef SYS_gettid
 264 // i386: 224, ia64: 1105, amd64: 186, sparc 143
 265 #ifdef __ia64__
 266 #define SYS_gettid 1105
 267 #elif __i386__
 268 #define SYS_gettid 224
 269 #elif __amd64__
 270 #define SYS_gettid 186
 271 #elif __sparc__
 272 #define SYS_gettid 143
 273 #else
 274 #error define gettid for the arch
 275 #endif
 276 #endif
 277 
 278 // Cpu architecture string
 279 #if   defined(ZERO)
 280 static char cpu_arch[] = ZERO_LIBARCH;
 281 #elif defined(IA64)
 282 static char cpu_arch[] = "ia64";
 283 #elif defined(IA32)
 284 static char cpu_arch[] = "i386";
 285 #elif defined(AMD64)
 286 static char cpu_arch[] = "amd64";
 287 #elif defined(ARM)
 288 static char cpu_arch[] = "arm";
 289 #elif defined(PPC)
 290 static char cpu_arch[] = "ppc";
 291 #elif defined(SPARC)
 292 #  ifdef _LP64
 293 static char cpu_arch[] = "sparcv9";
 294 #  else
 295 static char cpu_arch[] = "sparc";
 296 #  endif
 297 #else
 298 #error Add appropriate cpu_arch setting
 299 #endif
 300 
 301 
 302 // pid_t gettid()
 303 //
 304 // Returns the kernel thread id of the currently running thread. Kernel
 305 // thread id is used to access /proc.
 306 //
 307 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
 308 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
 309 //
 310 pid_t os::Linux::gettid() {
 311   int rslt = syscall(SYS_gettid);
 312   if (rslt == -1) {
 313      // old kernel, no NPTL support
 314      return getpid();
 315   } else {
 316      return (pid_t)rslt;
 317   }
 318 }
 319 
 320 // Most versions of linux have a bug where the number of processors are
 321 // determined by looking at the /proc file system.  In a chroot environment,
 322 // the system call returns 1.  This causes the VM to act as if it is
 323 // a single processor and elide locking (see is_MP() call).
 324 static bool unsafe_chroot_detected = false;
 325 static const char *unstable_chroot_error = "/proc file system not found.\n"
 326                      "Java may be unstable running multithreaded in a chroot "
 327                      "environment on Linux when /proc filesystem is not mounted.";
 328 
 329 void os::Linux::initialize_system_info() {
 330   set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
 331   if (processor_count() == 1) {
 332     pid_t pid = os::Linux::gettid();
 333     char fname[32];
 334     jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
 335     FILE *fp = fopen(fname, "r");
 336     if (fp == NULL) {
 337       unsafe_chroot_detected = true;
 338     } else {
 339       fclose(fp);
 340     }
 341   }
 342   _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
 343   assert(processor_count() > 0, "linux error");
 344 }
 345 
 346 void os::init_system_properties_values() {
 347 //  char arch[12];
 348 //  sysinfo(SI_ARCHITECTURE, arch, sizeof(arch));
 349 
 350   // The next steps are taken in the product version:
 351   //
 352   // Obtain the JAVA_HOME value from the location of libjvm[_g].so.
 353   // This library should be located at:
 354   // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm[_g].so.
 355   //
 356   // If "/jre/lib/" appears at the right place in the path, then we
 357   // assume libjvm[_g].so is installed in a JDK and we use this path.
 358   //
 359   // Otherwise exit with message: "Could not create the Java virtual machine."
 360   //
 361   // The following extra steps are taken in the debugging version:
 362   //
 363   // If "/jre/lib/" does NOT appear at the right place in the path
 364   // instead of exit check for $JAVA_HOME environment variable.
 365   //
 366   // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
 367   // then we append a fake suffix "hotspot/libjvm[_g].so" to this path so
 368   // it looks like libjvm[_g].so is installed there
 369   // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm[_g].so.
 370   //
 371   // Otherwise exit.
 372   //
 373   // Important note: if the location of libjvm.so changes this
 374   // code needs to be changed accordingly.
 375 
 376   // The next few definitions allow the code to be verbatim:
 377 #define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n))
 378 #define getenv(n) ::getenv(n)
 379 
 380 /*
 381  * See ld(1):
 382  *      The linker uses the following search paths to locate required
 383  *      shared libraries:
 384  *        1: ...
 385  *        ...
 386  *        7: The default directories, normally /lib and /usr/lib.
 387  */
 388 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
 389 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
 390 #else
 391 #define DEFAULT_LIBPATH "/lib:/usr/lib"
 392 #endif
 393 
 394 #define EXTENSIONS_DIR  "/lib/ext"
 395 #define ENDORSED_DIR    "/lib/endorsed"
 396 #define REG_DIR         "/usr/java/packages"
 397 
 398   {
 399     /* sysclasspath, java_home, dll_dir */
 400     {
 401         char *home_path;
 402         char *dll_path;
 403         char *pslash;
 404         char buf[MAXPATHLEN];
 405         os::jvm_path(buf, sizeof(buf));
 406 
 407         // Found the full path to libjvm.so.
 408         // Now cut the path to <java_home>/jre if we can.
 409         *(strrchr(buf, '/')) = '\0';  /* get rid of /libjvm.so */
 410         pslash = strrchr(buf, '/');
 411         if (pslash != NULL)
 412             *pslash = '\0';           /* get rid of /{client|server|hotspot} */
 413         dll_path = malloc(strlen(buf) + 1);
 414         if (dll_path == NULL)
 415             return;
 416         strcpy(dll_path, buf);
 417         Arguments::set_dll_dir(dll_path);
 418 
 419         if (pslash != NULL) {
 420             pslash = strrchr(buf, '/');
 421             if (pslash != NULL) {
 422                 *pslash = '\0';       /* get rid of /<arch> */
 423                 pslash = strrchr(buf, '/');
 424                 if (pslash != NULL)
 425                     *pslash = '\0';   /* get rid of /lib */
 426             }
 427         }
 428 
 429         home_path = malloc(strlen(buf) + 1);
 430         if (home_path == NULL)
 431             return;
 432         strcpy(home_path, buf);
 433         Arguments::set_java_home(home_path);
 434 
 435         if (!set_boot_path('/', ':'))
 436             return;
 437     }
 438 
 439     /*
 440      * Where to look for native libraries
 441      *
 442      * Note: Due to a legacy implementation, most of the library path
 443      * is set in the launcher.  This was to accomodate linking restrictions
 444      * on legacy Linux implementations (which are no longer supported).
 445      * Eventually, all the library path setting will be done here.
 446      *
 447      * However, to prevent the proliferation of improperly built native
 448      * libraries, the new path component /usr/java/packages is added here.
 449      * Eventually, all the library path setting will be done here.
 450      */
 451     {
 452         char *ld_library_path;
 453 
 454         /*
 455          * Construct the invariant part of ld_library_path. Note that the
 456          * space for the colon and the trailing null are provided by the
 457          * nulls included by the sizeof operator (so actually we allocate
 458          * a byte more than necessary).
 459          */
 460         ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") +
 461             strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH));
 462         sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch);
 463 
 464         /*
 465          * Get the user setting of LD_LIBRARY_PATH, and prepended it.  It
 466          * should always exist (until the legacy problem cited above is
 467          * addressed).
 468          */
 469         char *v = getenv("LD_LIBRARY_PATH");
 470         if (v != NULL) {
 471             char *t = ld_library_path;
 472             /* That's +1 for the colon and +1 for the trailing '\0' */
 473             ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1);
 474             sprintf(ld_library_path, "%s:%s", v, t);
 475         }
 476         Arguments::set_library_path(ld_library_path);
 477     }
 478 
 479     /*
 480      * Extensions directories.
 481      *
 482      * Note that the space for the colon and the trailing null are provided
 483      * by the nulls included by the sizeof operator (so actually one byte more
 484      * than necessary is allocated).
 485      */
 486     {
 487         char *buf = malloc(strlen(Arguments::get_java_home()) +
 488             sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR));
 489         sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR,
 490             Arguments::get_java_home());
 491         Arguments::set_ext_dirs(buf);
 492     }
 493 
 494     /* Endorsed standards default directory. */
 495     {
 496         char * buf;
 497         buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR));
 498         sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
 499         Arguments::set_endorsed_dirs(buf);
 500     }
 501   }
 502 
 503 #undef malloc
 504 #undef getenv
 505 #undef EXTENSIONS_DIR
 506 #undef ENDORSED_DIR
 507 
 508   // Done
 509   return;
 510 }
 511 
 512 ////////////////////////////////////////////////////////////////////////////////
 513 // breakpoint support
 514 
 515 void os::breakpoint() {
 516   BREAKPOINT;
 517 }
 518 
 519 extern "C" void breakpoint() {
 520   // use debugger to set breakpoint here
 521 }
 522 
 523 ////////////////////////////////////////////////////////////////////////////////
 524 // signal support
 525 
 526 debug_only(static bool signal_sets_initialized = false);
 527 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
 528 
 529 bool os::Linux::is_sig_ignored(int sig) {
 530       struct sigaction oact;
 531       sigaction(sig, (struct sigaction*)NULL, &oact);
 532       void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*,  oact.sa_sigaction)
 533                                      : CAST_FROM_FN_PTR(void*,  oact.sa_handler);
 534       if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
 535            return true;
 536       else
 537            return false;
 538 }
 539 
 540 void os::Linux::signal_sets_init() {
 541   // Should also have an assertion stating we are still single-threaded.
 542   assert(!signal_sets_initialized, "Already initialized");
 543   // Fill in signals that are necessarily unblocked for all threads in
 544   // the VM. Currently, we unblock the following signals:
 545   // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
 546   //                         by -Xrs (=ReduceSignalUsage));
 547   // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
 548   // other threads. The "ReduceSignalUsage" boolean tells us not to alter
 549   // the dispositions or masks wrt these signals.
 550   // Programs embedding the VM that want to use the above signals for their
 551   // own purposes must, at this time, use the "-Xrs" option to prevent
 552   // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
 553   // (See bug 4345157, and other related bugs).
 554   // In reality, though, unblocking these signals is really a nop, since
 555   // these signals are not blocked by default.
 556   sigemptyset(&unblocked_sigs);
 557   sigemptyset(&allowdebug_blocked_sigs);
 558   sigaddset(&unblocked_sigs, SIGILL);
 559   sigaddset(&unblocked_sigs, SIGSEGV);
 560   sigaddset(&unblocked_sigs, SIGBUS);
 561   sigaddset(&unblocked_sigs, SIGFPE);
 562   sigaddset(&unblocked_sigs, SR_signum);
 563 
 564   if (!ReduceSignalUsage) {
 565    if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
 566       sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
 567       sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
 568    }
 569    if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
 570       sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
 571       sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
 572    }
 573    if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
 574       sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
 575       sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
 576    }
 577   }
 578   // Fill in signals that are blocked by all but the VM thread.
 579   sigemptyset(&vm_sigs);
 580   if (!ReduceSignalUsage)
 581     sigaddset(&vm_sigs, BREAK_SIGNAL);
 582   debug_only(signal_sets_initialized = true);
 583 
 584 }
 585 
 586 // These are signals that are unblocked while a thread is running Java.
 587 // (For some reason, they get blocked by default.)
 588 sigset_t* os::Linux::unblocked_signals() {
 589   assert(signal_sets_initialized, "Not initialized");
 590   return &unblocked_sigs;
 591 }
 592 
 593 // These are the signals that are blocked while a (non-VM) thread is
 594 // running Java. Only the VM thread handles these signals.
 595 sigset_t* os::Linux::vm_signals() {
 596   assert(signal_sets_initialized, "Not initialized");
 597   return &vm_sigs;
 598 }
 599 
 600 // These are signals that are blocked during cond_wait to allow debugger in
 601 sigset_t* os::Linux::allowdebug_blocked_signals() {
 602   assert(signal_sets_initialized, "Not initialized");
 603   return &allowdebug_blocked_sigs;
 604 }
 605 
 606 void os::Linux::hotspot_sigmask(Thread* thread) {
 607 
 608   //Save caller's signal mask before setting VM signal mask
 609   sigset_t caller_sigmask;
 610   pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
 611 
 612   OSThread* osthread = thread->osthread();
 613   osthread->set_caller_sigmask(caller_sigmask);
 614 
 615   pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
 616 
 617   if (!ReduceSignalUsage) {
 618     if (thread->is_VM_thread()) {
 619       // Only the VM thread handles BREAK_SIGNAL ...
 620       pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
 621     } else {
 622       // ... all other threads block BREAK_SIGNAL
 623       pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
 624     }
 625   }
 626 }
 627 
 628 //////////////////////////////////////////////////////////////////////////////
 629 // detecting pthread library
 630 
 631 void os::Linux::libpthread_init() {
 632   // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
 633   // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
 634   // generic name for earlier versions.
 635   // Define macros here so we can build HotSpot on old systems.
 636 # ifndef _CS_GNU_LIBC_VERSION
 637 # define _CS_GNU_LIBC_VERSION 2
 638 # endif
 639 # ifndef _CS_GNU_LIBPTHREAD_VERSION
 640 # define _CS_GNU_LIBPTHREAD_VERSION 3
 641 # endif
 642 
 643   size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
 644   if (n > 0) {
 645      char *str = (char *)malloc(n);
 646      confstr(_CS_GNU_LIBC_VERSION, str, n);
 647      os::Linux::set_glibc_version(str);
 648   } else {
 649      // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
 650      static char _gnu_libc_version[32];
 651      jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
 652               "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
 653      os::Linux::set_glibc_version(_gnu_libc_version);
 654   }
 655 
 656   n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
 657   if (n > 0) {
 658      char *str = (char *)malloc(n);
 659      confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
 660      // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
 661      // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
 662      // is the case. LinuxThreads has a hard limit on max number of threads.
 663      // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
 664      // On the other hand, NPTL does not have such a limit, sysconf()
 665      // will return -1 and errno is not changed. Check if it is really NPTL.
 666      if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
 667          strstr(str, "NPTL") &&
 668          sysconf(_SC_THREAD_THREADS_MAX) > 0) {
 669        free(str);
 670        os::Linux::set_libpthread_version("linuxthreads");
 671      } else {
 672        os::Linux::set_libpthread_version(str);
 673      }
 674   } else {
 675     // glibc before 2.3.2 only has LinuxThreads.
 676     os::Linux::set_libpthread_version("linuxthreads");
 677   }
 678 
 679   if (strstr(libpthread_version(), "NPTL")) {
 680      os::Linux::set_is_NPTL();
 681   } else {
 682      os::Linux::set_is_LinuxThreads();
 683   }
 684 
 685   // LinuxThreads have two flavors: floating-stack mode, which allows variable
 686   // stack size; and fixed-stack mode. NPTL is always floating-stack.
 687   if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
 688      os::Linux::set_is_floating_stack();
 689   }
 690 }
 691 
 692 /////////////////////////////////////////////////////////////////////////////
 693 // thread stack
 694 
 695 // Force Linux kernel to expand current thread stack. If "bottom" is close
 696 // to the stack guard, caller should block all signals.
 697 //
 698 // MAP_GROWSDOWN:
 699 //   A special mmap() flag that is used to implement thread stacks. It tells
 700 //   kernel that the memory region should extend downwards when needed. This
 701 //   allows early versions of LinuxThreads to only mmap the first few pages
 702 //   when creating a new thread. Linux kernel will automatically expand thread
 703 //   stack as needed (on page faults).
 704 //
 705 //   However, because the memory region of a MAP_GROWSDOWN stack can grow on
 706 //   demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
 707 //   region, it's hard to tell if the fault is due to a legitimate stack
 708 //   access or because of reading/writing non-exist memory (e.g. buffer
 709 //   overrun). As a rule, if the fault happens below current stack pointer,
 710 //   Linux kernel does not expand stack, instead a SIGSEGV is sent to the
 711 //   application (see Linux kernel fault.c).
 712 //
 713 //   This Linux feature can cause SIGSEGV when VM bangs thread stack for
 714 //   stack overflow detection.
 715 //
 716 //   Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
 717 //   not use this flag. However, the stack of initial thread is not created
 718 //   by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
 719 //   unlikely) that user code can create a thread with MAP_GROWSDOWN stack
 720 //   and then attach the thread to JVM.
 721 //
 722 // To get around the problem and allow stack banging on Linux, we need to
 723 // manually expand thread stack after receiving the SIGSEGV.
 724 //
 725 // There are two ways to expand thread stack to address "bottom", we used
 726 // both of them in JVM before 1.5:
 727 //   1. adjust stack pointer first so that it is below "bottom", and then
 728 //      touch "bottom"
 729 //   2. mmap() the page in question
 730 //
 731 // Now alternate signal stack is gone, it's harder to use 2. For instance,
 732 // if current sp is already near the lower end of page 101, and we need to
 733 // call mmap() to map page 100, it is possible that part of the mmap() frame
 734 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
 735 // That will destroy the mmap() frame and cause VM to crash.
 736 //
 737 // The following code works by adjusting sp first, then accessing the "bottom"
 738 // page to force a page fault. Linux kernel will then automatically expand the
 739 // stack mapping.
 740 //
 741 // _expand_stack_to() assumes its frame size is less than page size, which
 742 // should always be true if the function is not inlined.
 743 
 744 #if __GNUC__ < 3    // gcc 2.x does not support noinline attribute
 745 #define NOINLINE
 746 #else
 747 #define NOINLINE __attribute__ ((noinline))
 748 #endif
 749 
 750 static void _expand_stack_to(address bottom) NOINLINE;
 751 
 752 static void _expand_stack_to(address bottom) {
 753   address sp;
 754   size_t size;
 755   volatile char *p;
 756 
 757   // Adjust bottom to point to the largest address within the same page, it
 758   // gives us a one-page buffer if alloca() allocates slightly more memory.
 759   bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
 760   bottom += os::Linux::page_size() - 1;
 761 
 762   // sp might be slightly above current stack pointer; if that's the case, we
 763   // will alloca() a little more space than necessary, which is OK. Don't use
 764   // os::current_stack_pointer(), as its result can be slightly below current
 765   // stack pointer, causing us to not alloca enough to reach "bottom".
 766   sp = (address)&sp;
 767 
 768   if (sp > bottom) {
 769     size = sp - bottom;
 770     p = (volatile char *)alloca(size);
 771     assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
 772     p[0] = '\0';
 773   }
 774 }
 775 
 776 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
 777   assert(t!=NULL, "just checking");
 778   assert(t->osthread()->expanding_stack(), "expand should be set");
 779   assert(t->stack_base() != NULL, "stack_base was not initialized");
 780 
 781   if (addr <  t->stack_base() && addr >= t->stack_yellow_zone_base()) {
 782     sigset_t mask_all, old_sigset;
 783     sigfillset(&mask_all);
 784     pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
 785     _expand_stack_to(addr);
 786     pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
 787     return true;
 788   }
 789   return false;
 790 }
 791 
 792 //////////////////////////////////////////////////////////////////////////////
 793 // create new thread
 794 
 795 static address highest_vm_reserved_address();
 796 
 797 // check if it's safe to start a new thread
 798 static bool _thread_safety_check(Thread* thread) {
 799   if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
 800     // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
 801     //   Heap is mmap'ed at lower end of memory space. Thread stacks are
 802     //   allocated (MAP_FIXED) from high address space. Every thread stack
 803     //   occupies a fixed size slot (usually 2Mbytes, but user can change
 804     //   it to other values if they rebuild LinuxThreads).
 805     //
 806     // Problem with MAP_FIXED is that mmap() can still succeed even part of
 807     // the memory region has already been mmap'ed. That means if we have too
 808     // many threads and/or very large heap, eventually thread stack will
 809     // collide with heap.
 810     //
 811     // Here we try to prevent heap/stack collision by comparing current
 812     // stack bottom with the highest address that has been mmap'ed by JVM
 813     // plus a safety margin for memory maps created by native code.
 814     //
 815     // This feature can be disabled by setting ThreadSafetyMargin to 0
 816     //
 817     if (ThreadSafetyMargin > 0) {
 818       address stack_bottom = os::current_stack_base() - os::current_stack_size();
 819 
 820       // not safe if our stack extends below the safety margin
 821       return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
 822     } else {
 823       return true;
 824     }
 825   } else {
 826     // Floating stack LinuxThreads or NPTL:
 827     //   Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
 828     //   there's not enough space left, pthread_create() will fail. If we come
 829     //   here, that means enough space has been reserved for stack.
 830     return true;
 831   }
 832 }
 833 
 834 // Thread start routine for all newly created threads
 835 static void *java_start(Thread *thread) {
 836   // Try to randomize the cache line index of hot stack frames.
 837   // This helps when threads of the same stack traces evict each other's
 838   // cache lines. The threads can be either from the same JVM instance, or
 839   // from different JVM instances. The benefit is especially true for
 840   // processors with hyperthreading technology.
 841   static int counter = 0;
 842   int pid = os::current_process_id();
 843   alloca(((pid ^ counter++) & 7) * 128);
 844 
 845   ThreadLocalStorage::set_thread(thread);
 846 
 847   OSThread* osthread = thread->osthread();
 848   Monitor* sync = osthread->startThread_lock();
 849 
 850   // non floating stack LinuxThreads needs extra check, see above
 851   if (!_thread_safety_check(thread)) {
 852     // notify parent thread
 853     MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
 854     osthread->set_state(ZOMBIE);
 855     sync->notify_all();
 856     return NULL;
 857   }
 858 
 859   // thread_id is kernel thread id (similar to Solaris LWP id)
 860   osthread->set_thread_id(os::Linux::gettid());
 861 
 862   if (UseNUMA) {
 863     int lgrp_id = os::numa_get_group_id();
 864     if (lgrp_id != -1) {
 865       thread->set_lgrp_id(lgrp_id);
 866     }
 867   }
 868   // initialize signal mask for this thread
 869   os::Linux::hotspot_sigmask(thread);
 870 
 871   // initialize floating point control register
 872   os::Linux::init_thread_fpu_state();
 873 
 874   // handshaking with parent thread
 875   {
 876     MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
 877 
 878     // notify parent thread
 879     osthread->set_state(INITIALIZED);
 880     sync->notify_all();
 881 
 882     // wait until os::start_thread()
 883     while (osthread->get_state() == INITIALIZED) {
 884       sync->wait(Mutex::_no_safepoint_check_flag);
 885     }
 886   }
 887 
 888   // call one more level start routine
 889   thread->run();
 890 
 891   return 0;
 892 }
 893 
 894 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
 895   assert(thread->osthread() == NULL, "caller responsible");
 896 
 897   // Allocate the OSThread object
 898   OSThread* osthread = new OSThread(NULL, NULL);
 899   if (osthread == NULL) {
 900     return false;
 901   }
 902 
 903   // set the correct thread state
 904   osthread->set_thread_type(thr_type);
 905 
 906   // Initial state is ALLOCATED but not INITIALIZED
 907   osthread->set_state(ALLOCATED);
 908 
 909   thread->set_osthread(osthread);
 910 
 911   // init thread attributes
 912   pthread_attr_t attr;
 913   pthread_attr_init(&attr);
 914   pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 915 
 916   // stack size
 917   if (os::Linux::supports_variable_stack_size()) {
 918     // calculate stack size if it's not specified by caller
 919     if (stack_size == 0) {
 920       stack_size = os::Linux::default_stack_size(thr_type);
 921 
 922       switch (thr_type) {
 923       case os::java_thread:
 924         // Java threads use ThreadStackSize which default value can be
 925         // changed with the flag -Xss
 926         assert (JavaThread::stack_size_at_create() > 0, "this should be set");
 927         stack_size = JavaThread::stack_size_at_create();
 928         break;
 929       case os::compiler_thread:
 930         if (CompilerThreadStackSize > 0) {
 931           stack_size = (size_t)(CompilerThreadStackSize * K);
 932           break;
 933         } // else fall through:
 934           // use VMThreadStackSize if CompilerThreadStackSize is not defined
 935       case os::vm_thread:
 936       case os::pgc_thread:
 937       case os::cgc_thread:
 938       case os::watcher_thread:
 939         if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
 940         break;
 941       }
 942     }
 943 
 944     stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
 945     pthread_attr_setstacksize(&attr, stack_size);
 946   } else {
 947     // let pthread_create() pick the default value.
 948   }
 949 
 950   // glibc guard page
 951   pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
 952 
 953   ThreadState state;
 954 
 955   {
 956     // Serialize thread creation if we are running with fixed stack LinuxThreads
 957     bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
 958     if (lock) {
 959       os::Linux::createThread_lock()->lock_without_safepoint_check();
 960     }
 961 
 962     pthread_t tid;
 963     int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
 964 
 965     pthread_attr_destroy(&attr);
 966 
 967     if (ret != 0) {
 968       if (PrintMiscellaneous && (Verbose || WizardMode)) {
 969         perror("pthread_create()");
 970       }
 971       // Need to clean up stuff we've allocated so far
 972       thread->set_osthread(NULL);
 973       delete osthread;
 974       if (lock) os::Linux::createThread_lock()->unlock();
 975       return false;
 976     }
 977 
 978     // Store pthread info into the OSThread
 979     osthread->set_pthread_id(tid);
 980 
 981     // Wait until child thread is either initialized or aborted
 982     {
 983       Monitor* sync_with_child = osthread->startThread_lock();
 984       MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
 985       while ((state = osthread->get_state()) == ALLOCATED) {
 986         sync_with_child->wait(Mutex::_no_safepoint_check_flag);
 987       }
 988     }
 989 
 990     if (lock) {
 991       os::Linux::createThread_lock()->unlock();
 992     }
 993   }
 994 
 995   // Aborted due to thread limit being reached
 996   if (state == ZOMBIE) {
 997       thread->set_osthread(NULL);
 998       delete osthread;
 999       return false;
1000   }
1001 
1002   // The thread is returned suspended (in state INITIALIZED),
1003   // and is started higher up in the call chain
1004   assert(state == INITIALIZED, "race condition");
1005   return true;
1006 }
1007 
1008 /////////////////////////////////////////////////////////////////////////////
1009 // attach existing thread
1010 
1011 // bootstrap the main thread
1012 bool os::create_main_thread(JavaThread* thread) {
1013   assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
1014   return create_attached_thread(thread);
1015 }
1016 
1017 bool os::create_attached_thread(JavaThread* thread) {
1018 #ifdef ASSERT
1019     thread->verify_not_published();
1020 #endif
1021 
1022   // Allocate the OSThread object
1023   OSThread* osthread = new OSThread(NULL, NULL);
1024 
1025   if (osthread == NULL) {
1026     return false;
1027   }
1028 
1029   // Store pthread info into the OSThread
1030   osthread->set_thread_id(os::Linux::gettid());
1031   osthread->set_pthread_id(::pthread_self());
1032 
1033   // initialize floating point control register
1034   os::Linux::init_thread_fpu_state();
1035 
1036   // Initial thread state is RUNNABLE
1037   osthread->set_state(RUNNABLE);
1038 
1039   thread->set_osthread(osthread);
1040 
1041   if (UseNUMA) {
1042     int lgrp_id = os::numa_get_group_id();
1043     if (lgrp_id != -1) {
1044       thread->set_lgrp_id(lgrp_id);
1045     }
1046   }
1047 
1048   if (os::Linux::is_initial_thread()) {
1049     // If current thread is initial thread, its stack is mapped on demand,
1050     // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
1051     // the entire stack region to avoid SEGV in stack banging.
1052     // It is also useful to get around the heap-stack-gap problem on SuSE
1053     // kernel (see 4821821 for details). We first expand stack to the top
1054     // of yellow zone, then enable stack yellow zone (order is significant,
1055     // enabling yellow zone first will crash JVM on SuSE Linux), so there
1056     // is no gap between the last two virtual memory regions.
1057 
1058     JavaThread *jt = (JavaThread *)thread;
1059     address addr = jt->stack_yellow_zone_base();
1060     assert(addr != NULL, "initialization problem?");
1061     assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
1062 
1063     osthread->set_expanding_stack();
1064     os::Linux::manually_expand_stack(jt, addr);
1065     osthread->clear_expanding_stack();
1066   }
1067 
1068   // initialize signal mask for this thread
1069   // and save the caller's signal mask
1070   os::Linux::hotspot_sigmask(thread);
1071 
1072   return true;
1073 }
1074 
1075 void os::pd_start_thread(Thread* thread) {
1076   OSThread * osthread = thread->osthread();
1077   assert(osthread->get_state() != INITIALIZED, "just checking");
1078   Monitor* sync_with_child = osthread->startThread_lock();
1079   MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
1080   sync_with_child->notify();
1081 }
1082 
1083 // Free Linux resources related to the OSThread
1084 void os::free_thread(OSThread* osthread) {
1085   assert(osthread != NULL, "osthread not set");
1086 
1087   if (Thread::current()->osthread() == osthread) {
1088     // Restore caller's signal mask
1089     sigset_t sigmask = osthread->caller_sigmask();
1090     pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
1091    }
1092 
1093   delete osthread;
1094 }
1095 
1096 //////////////////////////////////////////////////////////////////////////////
1097 // thread local storage
1098 
1099 int os::allocate_thread_local_storage() {
1100   pthread_key_t key;
1101   int rslt = pthread_key_create(&key, NULL);
1102   assert(rslt == 0, "cannot allocate thread local storage");
1103   return (int)key;
1104 }
1105 
1106 // Note: This is currently not used by VM, as we don't destroy TLS key
1107 // on VM exit.
1108 void os::free_thread_local_storage(int index) {
1109   int rslt = pthread_key_delete((pthread_key_t)index);
1110   assert(rslt == 0, "invalid index");
1111 }
1112 
1113 void os::thread_local_storage_at_put(int index, void* value) {
1114   int rslt = pthread_setspecific((pthread_key_t)index, value);
1115   assert(rslt == 0, "pthread_setspecific failed");
1116 }
1117 
1118 extern "C" Thread* get_thread() {
1119   return ThreadLocalStorage::thread();
1120 }
1121 
1122 //////////////////////////////////////////////////////////////////////////////
1123 // initial thread
1124 
1125 // Check if current thread is the initial thread, similar to Solaris thr_main.
1126 bool os::Linux::is_initial_thread(void) {
1127   char dummy;
1128   // If called before init complete, thread stack bottom will be null.
1129   // Can be called if fatal error occurs before initialization.
1130   if (initial_thread_stack_bottom() == NULL) return false;
1131   assert(initial_thread_stack_bottom() != NULL &&
1132          initial_thread_stack_size()   != 0,
1133          "os::init did not locate initial thread's stack region");
1134   if ((address)&dummy >= initial_thread_stack_bottom() &&
1135       (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1136        return true;
1137   else return false;
1138 }
1139 
1140 // Find the virtual memory area that contains addr
1141 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1142   FILE *fp = fopen("/proc/self/maps", "r");
1143   if (fp) {
1144     address low, high;
1145     while (!feof(fp)) {
1146       if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1147         if (low <= addr && addr < high) {
1148            if (vma_low)  *vma_low  = low;
1149            if (vma_high) *vma_high = high;
1150            fclose (fp);
1151            return true;
1152         }
1153       }
1154       for (;;) {
1155         int ch = fgetc(fp);
1156         if (ch == EOF || ch == (int)'\n') break;
1157       }
1158     }
1159     fclose(fp);
1160   }
1161   return false;
1162 }
1163 
1164 // Locate initial thread stack. This special handling of initial thread stack
1165 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1166 // bogus value for initial thread.
1167 void os::Linux::capture_initial_stack(size_t max_size) {
1168   // stack size is the easy part, get it from RLIMIT_STACK
1169   size_t stack_size;
1170   struct rlimit rlim;
1171   getrlimit(RLIMIT_STACK, &rlim);
1172   stack_size = rlim.rlim_cur;
1173 
1174   // 6308388: a bug in ld.so will relocate its own .data section to the
1175   //   lower end of primordial stack; reduce ulimit -s value a little bit
1176   //   so we won't install guard page on ld.so's data section.
1177   stack_size -= 2 * page_size();
1178 
1179   // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1180   //   7.1, in both cases we will get 2G in return value.
1181   // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1182   //   SuSE 7.2, Debian) can not handle alternate signal stack correctly
1183   //   for initial thread if its stack size exceeds 6M. Cap it at 2M,
1184   //   in case other parts in glibc still assumes 2M max stack size.
1185   // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1186 #ifndef IA64
1187   if (stack_size > 2 * K * K) stack_size = 2 * K * K;
1188 #else
1189   // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1190   if (stack_size > 4 * K * K) stack_size = 4 * K * K;
1191 #endif
1192 
1193   // Try to figure out where the stack base (top) is. This is harder.
1194   //
1195   // When an application is started, glibc saves the initial stack pointer in
1196   // a global variable "__libc_stack_end", which is then used by system
1197   // libraries. __libc_stack_end should be pretty close to stack top. The
1198   // variable is available since the very early days. However, because it is
1199   // a private interface, it could disappear in the future.
1200   //
1201   // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1202   // to __libc_stack_end, it is very close to stack top, but isn't the real
1203   // stack top. Note that /proc may not exist if VM is running as a chroot
1204   // program, so reading /proc/<pid>/stat could fail. Also the contents of
1205   // /proc/<pid>/stat could change in the future (though unlikely).
1206   //
1207   // We try __libc_stack_end first. If that doesn't work, look for
1208   // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1209   // as a hint, which should work well in most cases.
1210 
1211   uintptr_t stack_start;
1212 
1213   // try __libc_stack_end first
1214   uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1215   if (p && *p) {
1216     stack_start = *p;
1217   } else {
1218     // see if we can get the start_stack field from /proc/self/stat
1219     FILE *fp;
1220     int pid;
1221     char state;
1222     int ppid;
1223     int pgrp;
1224     int session;
1225     int nr;
1226     int tpgrp;
1227     unsigned long flags;
1228     unsigned long minflt;
1229     unsigned long cminflt;
1230     unsigned long majflt;
1231     unsigned long cmajflt;
1232     unsigned long utime;
1233     unsigned long stime;
1234     long cutime;
1235     long cstime;
1236     long prio;
1237     long nice;
1238     long junk;
1239     long it_real;
1240     uintptr_t start;
1241     uintptr_t vsize;
1242     intptr_t rss;
1243     uintptr_t rsslim;
1244     uintptr_t scodes;
1245     uintptr_t ecode;
1246     int i;
1247 
1248     // Figure what the primordial thread stack base is. Code is inspired
1249     // by email from Hans Boehm. /proc/self/stat begins with current pid,
1250     // followed by command name surrounded by parentheses, state, etc.
1251     char stat[2048];
1252     int statlen;
1253 
1254     fp = fopen("/proc/self/stat", "r");
1255     if (fp) {
1256       statlen = fread(stat, 1, 2047, fp);
1257       stat[statlen] = '\0';
1258       fclose(fp);
1259 
1260       // Skip pid and the command string. Note that we could be dealing with
1261       // weird command names, e.g. user could decide to rename java launcher
1262       // to "java 1.4.2 :)", then the stat file would look like
1263       //                1234 (java 1.4.2 :)) R ... ...
1264       // We don't really need to know the command string, just find the last
1265       // occurrence of ")" and then start parsing from there. See bug 4726580.
1266       char * s = strrchr(stat, ')');
1267 
1268       i = 0;
1269       if (s) {
1270         // Skip blank chars
1271         do s++; while (isspace(*s));
1272 
1273 #define _UFM UINTX_FORMAT
1274 #define _DFM INTX_FORMAT
1275 
1276         /*                                     1   1   1   1   1   1   1   1   1   1   2   2    2    2    2    2    2    2    2 */
1277         /*              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 */
1278         i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld " _UFM _UFM _DFM _UFM _UFM _UFM _UFM,
1279              &state,          /* 3  %c  */
1280              &ppid,           /* 4  %d  */
1281              &pgrp,           /* 5  %d  */
1282              &session,        /* 6  %d  */
1283              &nr,             /* 7  %d  */
1284              &tpgrp,          /* 8  %d  */
1285              &flags,          /* 9  %lu  */
1286              &minflt,         /* 10 %lu  */
1287              &cminflt,        /* 11 %lu  */
1288              &majflt,         /* 12 %lu  */
1289              &cmajflt,        /* 13 %lu  */
1290              &utime,          /* 14 %lu  */
1291              &stime,          /* 15 %lu  */
1292              &cutime,         /* 16 %ld  */
1293              &cstime,         /* 17 %ld  */
1294              &prio,           /* 18 %ld  */
1295              &nice,           /* 19 %ld  */
1296              &junk,           /* 20 %ld  */
1297              &it_real,        /* 21 %ld  */
1298              &start,          /* 22 UINTX_FORMAT */
1299              &vsize,          /* 23 UINTX_FORMAT */
1300              &rss,            /* 24 INTX_FORMAT  */
1301              &rsslim,         /* 25 UINTX_FORMAT */
1302              &scodes,         /* 26 UINTX_FORMAT */
1303              &ecode,          /* 27 UINTX_FORMAT */
1304              &stack_start);   /* 28 UINTX_FORMAT */
1305       }
1306 
1307 #undef _UFM
1308 #undef _DFM
1309 
1310       if (i != 28 - 2) {
1311          assert(false, "Bad conversion from /proc/self/stat");
1312          // product mode - assume we are the initial thread, good luck in the
1313          // embedded case.
1314          warning("Can't detect initial thread stack location - bad conversion");
1315          stack_start = (uintptr_t) &rlim;
1316       }
1317     } else {
1318       // For some reason we can't open /proc/self/stat (for example, running on
1319       // FreeBSD with a Linux emulator, or inside chroot), this should work for
1320       // most cases, so don't abort:
1321       warning("Can't detect initial thread stack location - no /proc/self/stat");
1322       stack_start = (uintptr_t) &rlim;
1323     }
1324   }
1325 
1326   // Now we have a pointer (stack_start) very close to the stack top, the
1327   // next thing to do is to figure out the exact location of stack top. We
1328   // can find out the virtual memory area that contains stack_start by
1329   // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1330   // and its upper limit is the real stack top. (again, this would fail if
1331   // running inside chroot, because /proc may not exist.)
1332 
1333   uintptr_t stack_top;
1334   address low, high;
1335   if (find_vma((address)stack_start, &low, &high)) {
1336     // success, "high" is the true stack top. (ignore "low", because initial
1337     // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1338     stack_top = (uintptr_t)high;
1339   } else {
1340     // failed, likely because /proc/self/maps does not exist
1341     warning("Can't detect initial thread stack location - find_vma failed");
1342     // best effort: stack_start is normally within a few pages below the real
1343     // stack top, use it as stack top, and reduce stack size so we won't put
1344     // guard page outside stack.
1345     stack_top = stack_start;
1346     stack_size -= 16 * page_size();
1347   }
1348 
1349   // stack_top could be partially down the page so align it
1350   stack_top = align_size_up(stack_top, page_size());
1351 
1352   if (max_size && stack_size > max_size) {
1353      _initial_thread_stack_size = max_size;
1354   } else {
1355      _initial_thread_stack_size = stack_size;
1356   }
1357 
1358   _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1359   _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1360 }
1361 
1362 ////////////////////////////////////////////////////////////////////////////////
1363 // time support
1364 
1365 // Time since start-up in seconds to a fine granularity.
1366 // Used by VMSelfDestructTimer and the MemProfiler.
1367 double os::elapsedTime() {
1368 
1369   return (double)(os::elapsed_counter()) * 0.000001;
1370 }
1371 
1372 jlong os::elapsed_counter() {
1373   timeval time;
1374   int status = gettimeofday(&time, NULL);
1375   return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count;
1376 }
1377 
1378 jlong os::elapsed_frequency() {
1379   return (1000 * 1000);
1380 }
1381 
1382 // For now, we say that linux does not support vtime.  I have no idea
1383 // whether it can actually be made to (DLD, 9/13/05).
1384 
1385 bool os::supports_vtime() { return false; }
1386 bool os::enable_vtime()   { return false; }
1387 bool os::vtime_enabled()  { return false; }
1388 double os::elapsedVTime() {
1389   // better than nothing, but not much
1390   return elapsedTime();
1391 }
1392 
1393 jlong os::javaTimeMillis() {
1394   timeval time;
1395   int status = gettimeofday(&time, NULL);
1396   assert(status != -1, "linux error");
1397   return jlong(time.tv_sec) * 1000  +  jlong(time.tv_usec / 1000);
1398 }
1399 
1400 #ifndef CLOCK_MONOTONIC
1401 #define CLOCK_MONOTONIC (1)
1402 #endif
1403 
1404 void os::Linux::clock_init() {
1405   // we do dlopen's in this particular order due to bug in linux
1406   // dynamical loader (see 6348968) leading to crash on exit
1407   void* handle = dlopen("librt.so.1", RTLD_LAZY);
1408   if (handle == NULL) {
1409     handle = dlopen("librt.so", RTLD_LAZY);
1410   }
1411 
1412   if (handle) {
1413     int (*clock_getres_func)(clockid_t, struct timespec*) =
1414            (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1415     int (*clock_gettime_func)(clockid_t, struct timespec*) =
1416            (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1417     if (clock_getres_func && clock_gettime_func) {
1418       // See if monotonic clock is supported by the kernel. Note that some
1419       // early implementations simply return kernel jiffies (updated every
1420       // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1421       // for nano time (though the monotonic property is still nice to have).
1422       // It's fixed in newer kernels, however clock_getres() still returns
1423       // 1/HZ. We check if clock_getres() works, but will ignore its reported
1424       // resolution for now. Hopefully as people move to new kernels, this
1425       // won't be a problem.
1426       struct timespec res;
1427       struct timespec tp;
1428       if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1429           clock_gettime_func(CLOCK_MONOTONIC, &tp)  == 0) {
1430         // yes, monotonic clock is supported
1431         _clock_gettime = clock_gettime_func;
1432       } else {
1433         // close librt if there is no monotonic clock
1434         dlclose(handle);
1435       }
1436     }
1437   }
1438 }
1439 
1440 #ifndef SYS_clock_getres
1441 
1442 #if defined(IA32) || defined(AMD64)
1443 #define SYS_clock_getres IA32_ONLY(266)  AMD64_ONLY(229)
1444 #define sys_clock_getres(x,y)  ::syscall(SYS_clock_getres, x, y)
1445 #else
1446 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1447 #define sys_clock_getres(x,y)  -1
1448 #endif
1449 
1450 #else
1451 #define sys_clock_getres(x,y)  ::syscall(SYS_clock_getres, x, y)
1452 #endif
1453 
1454 void os::Linux::fast_thread_clock_init() {
1455   if (!UseLinuxPosixThreadCPUClocks) {
1456     return;
1457   }
1458   clockid_t clockid;
1459   struct timespec tp;
1460   int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1461       (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1462 
1463   // Switch to using fast clocks for thread cpu time if
1464   // the sys_clock_getres() returns 0 error code.
1465   // Note, that some kernels may support the current thread
1466   // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1467   // returned by the pthread_getcpuclockid().
1468   // If the fast Posix clocks are supported then the sys_clock_getres()
1469   // must return at least tp.tv_sec == 0 which means a resolution
1470   // better than 1 sec. This is extra check for reliability.
1471 
1472   if(pthread_getcpuclockid_func &&
1473      pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1474      sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1475 
1476     _supports_fast_thread_cpu_time = true;
1477     _pthread_getcpuclockid = pthread_getcpuclockid_func;
1478   }
1479 }
1480 
1481 jlong os::javaTimeNanos() {
1482   if (Linux::supports_monotonic_clock()) {
1483     struct timespec tp;
1484     int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1485     assert(status == 0, "gettime error");
1486     jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1487     return result;
1488   } else {
1489     timeval time;
1490     int status = gettimeofday(&time, NULL);
1491     assert(status != -1, "linux error");
1492     jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1493     return 1000 * usecs;
1494   }
1495 }
1496 
1497 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1498   if (Linux::supports_monotonic_clock()) {
1499     info_ptr->max_value = ALL_64_BITS;
1500 
1501     // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1502     info_ptr->may_skip_backward = false;      // not subject to resetting or drifting
1503     info_ptr->may_skip_forward = false;       // not subject to resetting or drifting
1504   } else {
1505     // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1506     info_ptr->max_value = ALL_64_BITS;
1507 
1508     // gettimeofday is a real time clock so it skips
1509     info_ptr->may_skip_backward = true;
1510     info_ptr->may_skip_forward = true;
1511   }
1512 
1513   info_ptr->kind = JVMTI_TIMER_ELAPSED;                // elapsed not CPU time
1514 }
1515 
1516 // Return the real, user, and system times in seconds from an
1517 // arbitrary fixed point in the past.
1518 bool os::getTimesSecs(double* process_real_time,
1519                       double* process_user_time,
1520                       double* process_system_time) {
1521   struct tms ticks;
1522   clock_t real_ticks = times(&ticks);
1523 
1524   if (real_ticks == (clock_t) (-1)) {
1525     return false;
1526   } else {
1527     double ticks_per_second = (double) clock_tics_per_sec;
1528     *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1529     *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1530     *process_real_time = ((double) real_ticks) / ticks_per_second;
1531 
1532     return true;
1533   }
1534 }
1535 
1536 
1537 char * os::local_time_string(char *buf, size_t buflen) {
1538   struct tm t;
1539   time_t long_time;
1540   time(&long_time);
1541   localtime_r(&long_time, &t);
1542   jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1543                t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1544                t.tm_hour, t.tm_min, t.tm_sec);
1545   return buf;
1546 }
1547 
1548 struct tm* os::localtime_pd(const time_t* clock, struct tm*  res) {
1549   return localtime_r(clock, res);
1550 }
1551 
1552 ////////////////////////////////////////////////////////////////////////////////
1553 // runtime exit support
1554 
1555 // Note: os::shutdown() might be called very early during initialization, or
1556 // called from signal handler. Before adding something to os::shutdown(), make
1557 // sure it is async-safe and can handle partially initialized VM.
1558 void os::shutdown() {
1559 
1560   // allow PerfMemory to attempt cleanup of any persistent resources
1561   perfMemory_exit();
1562 
1563   // needs to remove object in file system
1564   AttachListener::abort();
1565 
1566   // flush buffered output, finish log files
1567   ostream_abort();
1568 
1569   // Check for abort hook
1570   abort_hook_t abort_hook = Arguments::abort_hook();
1571   if (abort_hook != NULL) {
1572     abort_hook();
1573   }
1574 
1575 }
1576 
1577 // Note: os::abort() might be called very early during initialization, or
1578 // called from signal handler. Before adding something to os::abort(), make
1579 // sure it is async-safe and can handle partially initialized VM.
1580 void os::abort(bool dump_core) {
1581   os::shutdown();
1582   if (dump_core) {
1583 #ifndef PRODUCT
1584     fdStream out(defaultStream::output_fd());
1585     out.print_raw("Current thread is ");
1586     char buf[16];
1587     jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1588     out.print_raw_cr(buf);
1589     out.print_raw_cr("Dumping core ...");
1590 #endif
1591     ::abort(); // dump core
1592   }
1593 
1594   ::exit(1);
1595 }
1596 
1597 // Die immediately, no exit hook, no abort hook, no cleanup.
1598 void os::die() {
1599   // _exit() on LinuxThreads only kills current thread
1600   ::abort();
1601 }
1602 
1603 // unused on linux for now.
1604 void os::set_error_file(const char *logfile) {}
1605 
1606 
1607 // This method is a copy of JDK's sysGetLastErrorString
1608 // from src/solaris/hpi/src/system_md.c
1609 
1610 size_t os::lasterror(char *buf, size_t len) {
1611 
1612   if (errno == 0)  return 0;
1613 
1614   const char *s = ::strerror(errno);
1615   size_t n = ::strlen(s);
1616   if (n >= len) {
1617     n = len - 1;
1618   }
1619   ::strncpy(buf, s, n);
1620   buf[n] = '\0';
1621   return n;
1622 }
1623 
1624 intx os::current_thread_id() { return (intx)pthread_self(); }
1625 int os::current_process_id() {
1626 
1627   // Under the old linux thread library, linux gives each thread
1628   // its own process id. Because of this each thread will return
1629   // a different pid if this method were to return the result
1630   // of getpid(2). Linux provides no api that returns the pid
1631   // of the launcher thread for the vm. This implementation
1632   // returns a unique pid, the pid of the launcher thread
1633   // that starts the vm 'process'.
1634 
1635   // Under the NPTL, getpid() returns the same pid as the
1636   // launcher thread rather than a unique pid per thread.
1637   // Use gettid() if you want the old pre NPTL behaviour.
1638 
1639   // if you are looking for the result of a call to getpid() that
1640   // returns a unique pid for the calling thread, then look at the
1641   // OSThread::thread_id() method in osThread_linux.hpp file
1642 
1643   return (int)(_initial_pid ? _initial_pid : getpid());
1644 }
1645 
1646 // DLL functions
1647 
1648 const char* os::dll_file_extension() { return ".so"; }
1649 
1650 // This must be hard coded because it's the system's temporary
1651 // directory not the java application's temp directory, ala java.io.tmpdir.
1652 const char* os::get_temp_directory() { return "/tmp"; }
1653 
1654 static bool file_exists(const char* filename) {
1655   struct stat statbuf;
1656   if (filename == NULL || strlen(filename) == 0) {
1657     return false;
1658   }
1659   return os::stat(filename, &statbuf) == 0;
1660 }
1661 
1662 void os::dll_build_name(char* buffer, size_t buflen,
1663                         const char* pname, const char* fname) {
1664   // Copied from libhpi
1665   const size_t pnamelen = pname ? strlen(pname) : 0;
1666 
1667   // Quietly truncate on buffer overflow.  Should be an error.
1668   if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1669       *buffer = '\0';
1670       return;
1671   }
1672 
1673   if (pnamelen == 0) {
1674     snprintf(buffer, buflen, "lib%s.so", fname);
1675   } else if (strchr(pname, *os::path_separator()) != NULL) {
1676     int n;
1677     char** pelements = split_path(pname, &n);
1678     for (int i = 0 ; i < n ; i++) {
1679       // Really shouldn't be NULL, but check can't hurt
1680       if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1681         continue; // skip the empty path values
1682       }
1683       snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1684       if (file_exists(buffer)) {
1685         break;
1686       }
1687     }
1688     // release the storage
1689     for (int i = 0 ; i < n ; i++) {
1690       if (pelements[i] != NULL) {
1691         FREE_C_HEAP_ARRAY(char, pelements[i]);
1692       }
1693     }
1694     if (pelements != NULL) {
1695       FREE_C_HEAP_ARRAY(char*, pelements);
1696     }
1697   } else {
1698     snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1699   }
1700 }
1701 
1702 const char* os::get_current_directory(char *buf, int buflen) {
1703   return getcwd(buf, buflen);
1704 }
1705 
1706 // check if addr is inside libjvm[_g].so
1707 bool os::address_is_in_vm(address addr) {
1708   static address libjvm_base_addr;
1709   Dl_info dlinfo;
1710 
1711   if (libjvm_base_addr == NULL) {
1712     dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo);
1713     libjvm_base_addr = (address)dlinfo.dli_fbase;
1714     assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1715   }
1716 
1717   if (dladdr((void *)addr, &dlinfo)) {
1718     if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1719   }
1720 
1721   return false;
1722 }
1723 
1724 bool os::dll_address_to_function_name(address addr, char *buf,
1725                                       int buflen, int *offset) {
1726   Dl_info dlinfo;
1727 
1728   if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) {
1729     if (buf != NULL) {
1730       if(!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1731         jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1732       }
1733     }
1734     if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1735     return true;
1736   } else if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != 0) {
1737     if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1738        dlinfo.dli_fname, buf, buflen, offset) == Decoder::no_error) {
1739        return true;
1740     }
1741   }
1742 
1743   if (buf != NULL) buf[0] = '\0';
1744   if (offset != NULL) *offset = -1;
1745   return false;
1746 }
1747 
1748 struct _address_to_library_name {
1749   address addr;          // input : memory address
1750   size_t  buflen;        //         size of fname
1751   char*   fname;         // output: library name
1752   address base;          //         library base addr
1753 };
1754 
1755 static int address_to_library_name_callback(struct dl_phdr_info *info,
1756                                             size_t size, void *data) {
1757   int i;
1758   bool found = false;
1759   address libbase = NULL;
1760   struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1761 
1762   // iterate through all loadable segments
1763   for (i = 0; i < info->dlpi_phnum; i++) {
1764     address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1765     if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1766       // base address of a library is the lowest address of its loaded
1767       // segments.
1768       if (libbase == NULL || libbase > segbase) {
1769         libbase = segbase;
1770       }
1771       // see if 'addr' is within current segment
1772       if (segbase <= d->addr &&
1773           d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1774         found = true;
1775       }
1776     }
1777   }
1778 
1779   // dlpi_name is NULL or empty if the ELF file is executable, return 0
1780   // so dll_address_to_library_name() can fall through to use dladdr() which
1781   // can figure out executable name from argv[0].
1782   if (found && info->dlpi_name && info->dlpi_name[0]) {
1783     d->base = libbase;
1784     if (d->fname) {
1785       jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1786     }
1787     return 1;
1788   }
1789   return 0;
1790 }
1791 
1792 bool os::dll_address_to_library_name(address addr, char* buf,
1793                                      int buflen, int* offset) {
1794   Dl_info dlinfo;
1795   struct _address_to_library_name data;
1796 
1797   // There is a bug in old glibc dladdr() implementation that it could resolve
1798   // to wrong library name if the .so file has a base address != NULL. Here
1799   // we iterate through the program headers of all loaded libraries to find
1800   // out which library 'addr' really belongs to. This workaround can be
1801   // removed once the minimum requirement for glibc is moved to 2.3.x.
1802   data.addr = addr;
1803   data.fname = buf;
1804   data.buflen = buflen;
1805   data.base = NULL;
1806   int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1807 
1808   if (rslt) {
1809      // buf already contains library name
1810      if (offset) *offset = addr - data.base;
1811      return true;
1812   } else if (dladdr((void*)addr, &dlinfo)){
1813      if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1814      if (offset) *offset = addr - (address)dlinfo.dli_fbase;
1815      return true;
1816   } else {
1817      if (buf) buf[0] = '\0';
1818      if (offset) *offset = -1;
1819      return false;
1820   }
1821 }
1822 
1823   // Loads .dll/.so and
1824   // in case of error it checks if .dll/.so was built for the
1825   // same architecture as Hotspot is running on
1826 
1827 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1828 {
1829   void * result= ::dlopen(filename, RTLD_LAZY);
1830   if (result != NULL) {
1831     // Successful loading
1832     return result;
1833   }
1834 
1835   Elf32_Ehdr elf_head;
1836 
1837   // Read system error message into ebuf
1838   // It may or may not be overwritten below
1839   ::strncpy(ebuf, ::dlerror(), ebuflen-1);
1840   ebuf[ebuflen-1]='\0';
1841   int diag_msg_max_length=ebuflen-strlen(ebuf);
1842   char* diag_msg_buf=ebuf+strlen(ebuf);
1843 
1844   if (diag_msg_max_length==0) {
1845     // No more space in ebuf for additional diagnostics message
1846     return NULL;
1847   }
1848 
1849 
1850   int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1851 
1852   if (file_descriptor < 0) {
1853     // Can't open library, report dlerror() message
1854     return NULL;
1855   }
1856 
1857   bool failed_to_read_elf_head=
1858     (sizeof(elf_head)!=
1859         (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1860 
1861   ::close(file_descriptor);
1862   if (failed_to_read_elf_head) {
1863     // file i/o error - report dlerror() msg
1864     return NULL;
1865   }
1866 
1867   typedef struct {
1868     Elf32_Half  code;         // Actual value as defined in elf.h
1869     Elf32_Half  compat_class; // Compatibility of archs at VM's sense
1870     char        elf_class;    // 32 or 64 bit
1871     char        endianess;    // MSB or LSB
1872     char*       name;         // String representation
1873   } arch_t;
1874 
1875   #ifndef EM_486
1876   #define EM_486          6               /* Intel 80486 */
1877   #endif
1878 
1879   static const arch_t arch_array[]={
1880     {EM_386,         EM_386,     ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1881     {EM_486,         EM_386,     ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1882     {EM_IA_64,       EM_IA_64,   ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1883     {EM_X86_64,      EM_X86_64,  ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1884     {EM_SPARC,       EM_SPARC,   ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1885     {EM_SPARC32PLUS, EM_SPARC,   ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1886     {EM_SPARCV9,     EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1887     {EM_PPC,         EM_PPC,     ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1888     {EM_PPC64,       EM_PPC64,   ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1889     {EM_ARM,         EM_ARM,     ELFCLASS32,   ELFDATA2LSB, (char*)"ARM"},
1890     {EM_S390,        EM_S390,    ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1891     {EM_ALPHA,       EM_ALPHA,   ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1892     {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1893     {EM_MIPS,        EM_MIPS,    ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1894     {EM_PARISC,      EM_PARISC,  ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1895     {EM_68K,         EM_68K,     ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1896   };
1897 
1898   #if  (defined IA32)
1899     static  Elf32_Half running_arch_code=EM_386;
1900   #elif   (defined AMD64)
1901     static  Elf32_Half running_arch_code=EM_X86_64;
1902   #elif  (defined IA64)
1903     static  Elf32_Half running_arch_code=EM_IA_64;
1904   #elif  (defined __sparc) && (defined _LP64)
1905     static  Elf32_Half running_arch_code=EM_SPARCV9;
1906   #elif  (defined __sparc) && (!defined _LP64)
1907     static  Elf32_Half running_arch_code=EM_SPARC;
1908   #elif  (defined __powerpc64__)
1909     static  Elf32_Half running_arch_code=EM_PPC64;
1910   #elif  (defined __powerpc__)
1911     static  Elf32_Half running_arch_code=EM_PPC;
1912   #elif  (defined ARM)
1913     static  Elf32_Half running_arch_code=EM_ARM;
1914   #elif  (defined S390)
1915     static  Elf32_Half running_arch_code=EM_S390;
1916   #elif  (defined ALPHA)
1917     static  Elf32_Half running_arch_code=EM_ALPHA;
1918   #elif  (defined MIPSEL)
1919     static  Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1920   #elif  (defined PARISC)
1921     static  Elf32_Half running_arch_code=EM_PARISC;
1922   #elif  (defined MIPS)
1923     static  Elf32_Half running_arch_code=EM_MIPS;
1924   #elif  (defined M68K)
1925     static  Elf32_Half running_arch_code=EM_68K;
1926   #else
1927     #error Method os::dll_load requires that one of following is defined:\
1928          IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
1929   #endif
1930 
1931   // Identify compatability class for VM's architecture and library's architecture
1932   // Obtain string descriptions for architectures
1933 
1934   arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1935   int running_arch_index=-1;
1936 
1937   for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
1938     if (running_arch_code == arch_array[i].code) {
1939       running_arch_index    = i;
1940     }
1941     if (lib_arch.code == arch_array[i].code) {
1942       lib_arch.compat_class = arch_array[i].compat_class;
1943       lib_arch.name         = arch_array[i].name;
1944     }
1945   }
1946 
1947   assert(running_arch_index != -1,
1948     "Didn't find running architecture code (running_arch_code) in arch_array");
1949   if (running_arch_index == -1) {
1950     // Even though running architecture detection failed
1951     // we may still continue with reporting dlerror() message
1952     return NULL;
1953   }
1954 
1955   if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1956     ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1957     return NULL;
1958   }
1959 
1960 #ifndef S390
1961   if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1962     ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1963     return NULL;
1964   }
1965 #endif // !S390
1966 
1967   if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
1968     if ( lib_arch.name!=NULL ) {
1969       ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1970         " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
1971         lib_arch.name, arch_array[running_arch_index].name);
1972     } else {
1973       ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1974       " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
1975         lib_arch.code,
1976         arch_array[running_arch_index].name);
1977     }
1978   }
1979 
1980   return NULL;
1981 }
1982 
1983 /*
1984  * glibc-2.0 libdl is not MT safe.  If you are building with any glibc,
1985  * chances are you might want to run the generated bits against glibc-2.0
1986  * libdl.so, so always use locking for any version of glibc.
1987  */
1988 void* os::dll_lookup(void* handle, const char* name) {
1989   pthread_mutex_lock(&dl_mutex);
1990   void* res = dlsym(handle, name);
1991   pthread_mutex_unlock(&dl_mutex);
1992   return res;
1993 }
1994 
1995 
1996 static bool _print_ascii_file(const char* filename, outputStream* st) {
1997   int fd = ::open(filename, O_RDONLY);
1998   if (fd == -1) {
1999      return false;
2000   }
2001 
2002   char buf[32];
2003   int bytes;
2004   while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2005     st->print_raw(buf, bytes);
2006   }
2007 
2008   ::close(fd);
2009 
2010   return true;
2011 }
2012 
2013 void os::print_dll_info(outputStream *st) {
2014    st->print_cr("Dynamic libraries:");
2015 
2016    char fname[32];
2017    pid_t pid = os::Linux::gettid();
2018 
2019    jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2020 
2021    if (!_print_ascii_file(fname, st)) {
2022      st->print("Can not get library information for pid = %d\n", pid);
2023    }
2024 }
2025 
2026 
2027 void os::print_os_info(outputStream* st) {
2028   st->print("OS:");
2029 
2030   // Try to identify popular distros.
2031   // Most Linux distributions have /etc/XXX-release file, which contains
2032   // the OS version string. Some have more than one /etc/XXX-release file
2033   // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.),
2034   // so the order is important.
2035   if (!_print_ascii_file("/etc/mandrake-release", st) &&
2036       !_print_ascii_file("/etc/sun-release", st) &&
2037       !_print_ascii_file("/etc/redhat-release", st) &&
2038       !_print_ascii_file("/etc/SuSE-release", st) &&
2039       !_print_ascii_file("/etc/turbolinux-release", st) &&
2040       !_print_ascii_file("/etc/gentoo-release", st) &&
2041       !_print_ascii_file("/etc/debian_version", st) &&
2042       !_print_ascii_file("/etc/ltib-release", st) &&
2043       !_print_ascii_file("/etc/angstrom-version", st)) {
2044       st->print("Linux");
2045   }
2046   st->cr();
2047 
2048   // kernel
2049   st->print("uname:");
2050   struct utsname name;
2051   uname(&name);
2052   st->print(name.sysname); st->print(" ");
2053   st->print(name.release); st->print(" ");
2054   st->print(name.version); st->print(" ");
2055   st->print(name.machine);
2056   st->cr();
2057 
2058   // Print warning if unsafe chroot environment detected
2059   if (unsafe_chroot_detected) {
2060     st->print("WARNING!! ");
2061     st->print_cr(unstable_chroot_error);
2062   }
2063 
2064   // libc, pthread
2065   st->print("libc:");
2066   st->print(os::Linux::glibc_version()); st->print(" ");
2067   st->print(os::Linux::libpthread_version()); st->print(" ");
2068   if (os::Linux::is_LinuxThreads()) {
2069      st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2070   }
2071   st->cr();
2072 
2073   // rlimit
2074   st->print("rlimit:");
2075   struct rlimit rlim;
2076 
2077   st->print(" STACK ");
2078   getrlimit(RLIMIT_STACK, &rlim);
2079   if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
2080   else st->print("%uk", rlim.rlim_cur >> 10);
2081 
2082   st->print(", CORE ");
2083   getrlimit(RLIMIT_CORE, &rlim);
2084   if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
2085   else st->print("%uk", rlim.rlim_cur >> 10);
2086 
2087   st->print(", NPROC ");
2088   getrlimit(RLIMIT_NPROC, &rlim);
2089   if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
2090   else st->print("%d", rlim.rlim_cur);
2091 
2092   st->print(", NOFILE ");
2093   getrlimit(RLIMIT_NOFILE, &rlim);
2094   if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
2095   else st->print("%d", rlim.rlim_cur);
2096 
2097   st->print(", AS ");
2098   getrlimit(RLIMIT_AS, &rlim);
2099   if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
2100   else st->print("%uk", rlim.rlim_cur >> 10);
2101   st->cr();
2102 
2103   // load average
2104   st->print("load average:");
2105   double loadavg[3];
2106   os::loadavg(loadavg, 3);
2107   st->print("%0.02f %0.02f %0.02f", loadavg[0], loadavg[1], loadavg[2]);
2108   st->cr();
2109 
2110   // meminfo
2111   st->print("\n/proc/meminfo:\n");
2112   _print_ascii_file("/proc/meminfo", st);
2113   st->cr();
2114 }
2115 
2116 void os::pd_print_cpu_info(outputStream* st) {
2117   st->print("\n/proc/cpuinfo:\n");
2118   if (!_print_ascii_file("/proc/cpuinfo", st)) {
2119     st->print("  <Not Available>");
2120   }
2121   st->cr();
2122 }
2123 
2124 void os::print_memory_info(outputStream* st) {
2125 
2126   st->print("Memory:");
2127   st->print(" %dk page", os::vm_page_size()>>10);
2128 
2129   // values in struct sysinfo are "unsigned long"
2130   struct sysinfo si;
2131   sysinfo(&si);
2132 
2133   st->print(", physical " UINT64_FORMAT "k",
2134             os::physical_memory() >> 10);
2135   st->print("(" UINT64_FORMAT "k free)",
2136             os::available_memory() >> 10);
2137   st->print(", swap " UINT64_FORMAT "k",
2138             ((jlong)si.totalswap * si.mem_unit) >> 10);
2139   st->print("(" UINT64_FORMAT "k free)",
2140             ((jlong)si.freeswap * si.mem_unit) >> 10);
2141   st->cr();
2142 }
2143 
2144 // Taken from /usr/include/bits/siginfo.h  Supposed to be architecture specific
2145 // but they're the same for all the linux arch that we support
2146 // and they're the same for solaris but there's no common place to put this.
2147 const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR",
2148                           "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG",
2149                           "ILL_COPROC", "ILL_BADSTK" };
2150 
2151 const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV",
2152                           "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES",
2153                           "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" };
2154 
2155 const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" };
2156 
2157 const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" };
2158 
2159 void os::print_siginfo(outputStream* st, void* siginfo) {
2160   st->print("siginfo:");
2161 
2162   const int buflen = 100;
2163   char buf[buflen];
2164   siginfo_t *si = (siginfo_t*)siginfo;
2165   st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen));
2166   if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) {
2167     st->print("si_errno=%s", buf);
2168   } else {
2169     st->print("si_errno=%d", si->si_errno);
2170   }
2171   const int c = si->si_code;
2172   assert(c > 0, "unexpected si_code");
2173   switch (si->si_signo) {
2174   case SIGILL:
2175     st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]);
2176     st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2177     break;
2178   case SIGFPE:
2179     st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]);
2180     st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2181     break;
2182   case SIGSEGV:
2183     st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]);
2184     st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2185     break;
2186   case SIGBUS:
2187     st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]);
2188     st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2189     break;
2190   default:
2191     st->print(", si_code=%d", si->si_code);
2192     // no si_addr
2193   }
2194 
2195   if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2196       UseSharedSpaces) {
2197     FileMapInfo* mapinfo = FileMapInfo::current_info();
2198     if (mapinfo->is_in_shared_space(si->si_addr)) {
2199       st->print("\n\nError accessing class data sharing archive."   \
2200                 " Mapped file inaccessible during execution, "      \
2201                 " possible disk/network problem.");
2202     }
2203   }
2204   st->cr();
2205 }
2206 
2207 
2208 static void print_signal_handler(outputStream* st, int sig,
2209                                  char* buf, size_t buflen);
2210 
2211 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2212   st->print_cr("Signal Handlers:");
2213   print_signal_handler(st, SIGSEGV, buf, buflen);
2214   print_signal_handler(st, SIGBUS , buf, buflen);
2215   print_signal_handler(st, SIGFPE , buf, buflen);
2216   print_signal_handler(st, SIGPIPE, buf, buflen);
2217   print_signal_handler(st, SIGXFSZ, buf, buflen);
2218   print_signal_handler(st, SIGILL , buf, buflen);
2219   print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2220   print_signal_handler(st, SR_signum, buf, buflen);
2221   print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2222   print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2223   print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2224   print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2225 }
2226 
2227 static char saved_jvm_path[MAXPATHLEN] = {0};
2228 
2229 // Find the full path to the current module, libjvm.so or libjvm_g.so
2230 void os::jvm_path(char *buf, jint buflen) {
2231   // Error checking.
2232   if (buflen < MAXPATHLEN) {
2233     assert(false, "must use a large-enough buffer");
2234     buf[0] = '\0';
2235     return;
2236   }
2237   // Lazy resolve the path to current module.
2238   if (saved_jvm_path[0] != 0) {
2239     strcpy(buf, saved_jvm_path);
2240     return;
2241   }
2242 
2243   char dli_fname[MAXPATHLEN];
2244   bool ret = dll_address_to_library_name(
2245                 CAST_FROM_FN_PTR(address, os::jvm_path),
2246                 dli_fname, sizeof(dli_fname), NULL);
2247   assert(ret != 0, "cannot locate libjvm");
2248   char *rp = realpath(dli_fname, buf);
2249   if (rp == NULL)
2250     return;
2251 
2252   if (Arguments::created_by_gamma_launcher()) {
2253     // Support for the gamma launcher.  Typical value for buf is
2254     // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so".  If "/jre/lib/" appears at
2255     // the right place in the string, then assume we are installed in a JDK and
2256     // we're done.  Otherwise, check for a JAVA_HOME environment variable and fix
2257     // up the path so it looks like libjvm.so is installed there (append a
2258     // fake suffix hotspot/libjvm.so).
2259     const char *p = buf + strlen(buf) - 1;
2260     for (int count = 0; p > buf && count < 5; ++count) {
2261       for (--p; p > buf && *p != '/'; --p)
2262         /* empty */ ;
2263     }
2264 
2265     if (strncmp(p, "/jre/lib/", 9) != 0) {
2266       // Look for JAVA_HOME in the environment.
2267       char* java_home_var = ::getenv("JAVA_HOME");
2268       if (java_home_var != NULL && java_home_var[0] != 0) {
2269         char* jrelib_p;
2270         int len;
2271 
2272         // Check the current module name "libjvm.so" or "libjvm_g.so".
2273         p = strrchr(buf, '/');
2274         assert(strstr(p, "/libjvm") == p, "invalid library name");
2275         p = strstr(p, "_g") ? "_g" : "";
2276 
2277         rp = realpath(java_home_var, buf);
2278         if (rp == NULL)
2279           return;
2280 
2281         // determine if this is a legacy image or modules image
2282         // modules image doesn't have "jre" subdirectory
2283         len = strlen(buf);
2284         jrelib_p = buf + len;
2285         snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2286         if (0 != access(buf, F_OK)) {
2287           snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2288         }
2289 
2290         if (0 == access(buf, F_OK)) {
2291           // Use current module name "libjvm[_g].so" instead of
2292           // "libjvm"debug_only("_g")".so" since for fastdebug version
2293           // we should have "libjvm.so" but debug_only("_g") adds "_g"!
2294           len = strlen(buf);
2295           snprintf(buf + len, buflen-len, "/hotspot/libjvm%s.so", p);
2296         } else {
2297           // Go back to path of .so
2298           rp = realpath(dli_fname, buf);
2299           if (rp == NULL)
2300             return;
2301         }
2302       }
2303     }
2304   }
2305 
2306   strcpy(saved_jvm_path, buf);
2307 }
2308 
2309 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2310   // no prefix required, not even "_"
2311 }
2312 
2313 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2314   // no suffix required
2315 }
2316 
2317 ////////////////////////////////////////////////////////////////////////////////
2318 // sun.misc.Signal support
2319 
2320 static volatile jint sigint_count = 0;
2321 
2322 static void
2323 UserHandler(int sig, void *siginfo, void *context) {
2324   // 4511530 - sem_post is serialized and handled by the manager thread. When
2325   // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2326   // don't want to flood the manager thread with sem_post requests.
2327   if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2328       return;
2329 
2330   // Ctrl-C is pressed during error reporting, likely because the error
2331   // handler fails to abort. Let VM die immediately.
2332   if (sig == SIGINT && is_error_reported()) {
2333      os::die();
2334   }
2335 
2336   os::signal_notify(sig);
2337 }
2338 
2339 void* os::user_handler() {
2340   return CAST_FROM_FN_PTR(void*, UserHandler);
2341 }
2342 
2343 extern "C" {
2344   typedef void (*sa_handler_t)(int);
2345   typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2346 }
2347 
2348 void* os::signal(int signal_number, void* handler) {
2349   struct sigaction sigAct, oldSigAct;
2350 
2351   sigfillset(&(sigAct.sa_mask));
2352   sigAct.sa_flags   = SA_RESTART|SA_SIGINFO;
2353   sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2354 
2355   if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2356     // -1 means registration failed
2357     return (void *)-1;
2358   }
2359 
2360   return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2361 }
2362 
2363 void os::signal_raise(int signal_number) {
2364   ::raise(signal_number);
2365 }
2366 
2367 /*
2368  * The following code is moved from os.cpp for making this
2369  * code platform specific, which it is by its very nature.
2370  */
2371 
2372 // Will be modified when max signal is changed to be dynamic
2373 int os::sigexitnum_pd() {
2374   return NSIG;
2375 }
2376 
2377 // a counter for each possible signal value
2378 static volatile jint pending_signals[NSIG+1] = { 0 };
2379 
2380 // Linux(POSIX) specific hand shaking semaphore.
2381 static sem_t sig_sem;
2382 
2383 void os::signal_init_pd() {
2384   // Initialize signal structures
2385   ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2386 
2387   // Initialize signal semaphore
2388   ::sem_init(&sig_sem, 0, 0);
2389 }
2390 
2391 void os::signal_notify(int sig) {
2392   Atomic::inc(&pending_signals[sig]);
2393   ::sem_post(&sig_sem);
2394 }
2395 
2396 static int check_pending_signals(bool wait) {
2397   Atomic::store(0, &sigint_count);
2398   for (;;) {
2399     for (int i = 0; i < NSIG + 1; i++) {
2400       jint n = pending_signals[i];
2401       if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2402         return i;
2403       }
2404     }
2405     if (!wait) {
2406       return -1;
2407     }
2408     JavaThread *thread = JavaThread::current();
2409     ThreadBlockInVM tbivm(thread);
2410 
2411     bool threadIsSuspended;
2412     do {
2413       thread->set_suspend_equivalent();
2414       // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2415       ::sem_wait(&sig_sem);
2416 
2417       // were we externally suspended while we were waiting?
2418       threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2419       if (threadIsSuspended) {
2420         //
2421         // The semaphore has been incremented, but while we were waiting
2422         // another thread suspended us. We don't want to continue running
2423         // while suspended because that would surprise the thread that
2424         // suspended us.
2425         //
2426         ::sem_post(&sig_sem);
2427 
2428         thread->java_suspend_self();
2429       }
2430     } while (threadIsSuspended);
2431   }
2432 }
2433 
2434 int os::signal_lookup() {
2435   return check_pending_signals(false);
2436 }
2437 
2438 int os::signal_wait() {
2439   return check_pending_signals(true);
2440 }
2441 
2442 ////////////////////////////////////////////////////////////////////////////////
2443 // Virtual Memory
2444 
2445 int os::vm_page_size() {
2446   // Seems redundant as all get out
2447   assert(os::Linux::page_size() != -1, "must call os::init");
2448   return os::Linux::page_size();
2449 }
2450 
2451 // Solaris allocates memory by pages.
2452 int os::vm_allocation_granularity() {
2453   assert(os::Linux::page_size() != -1, "must call os::init");
2454   return os::Linux::page_size();
2455 }
2456 
2457 // Rationale behind this function:
2458 //  current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2459 //  mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2460 //  samples for JITted code. Here we create private executable mapping over the code cache
2461 //  and then we can use standard (well, almost, as mapping can change) way to provide
2462 //  info for the reporting script by storing timestamp and location of symbol
2463 void linux_wrap_code(char* base, size_t size) {
2464   static volatile jint cnt = 0;
2465 
2466   if (!UseOprofile) {
2467     return;
2468   }
2469 
2470   char buf[PATH_MAX+1];
2471   int num = Atomic::add(1, &cnt);
2472 
2473   snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2474            os::get_temp_directory(), os::current_process_id(), num);
2475   unlink(buf);
2476 
2477   int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2478 
2479   if (fd != -1) {
2480     off_t rv = ::lseek(fd, size-2, SEEK_SET);
2481     if (rv != (off_t)-1) {
2482       if (::write(fd, "", 1) == 1) {
2483         mmap(base, size,
2484              PROT_READ|PROT_WRITE|PROT_EXEC,
2485              MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2486       }
2487     }
2488     ::close(fd);
2489     unlink(buf);
2490   }
2491 }
2492 
2493 // NOTE: Linux kernel does not really reserve the pages for us.
2494 //       All it does is to check if there are enough free pages
2495 //       left at the time of mmap(). This could be a potential
2496 //       problem.
2497 bool os::commit_memory(char* addr, size_t size, bool exec) {
2498   int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2499   uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2500                                    MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2501   if (res != (uintptr_t) MAP_FAILED) {
2502     if (UseNUMAInterleaving) {
2503       numa_make_global(addr, size);
2504     }
2505     return true;
2506   }
2507   return false;
2508 }
2509 
2510 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2511 #ifndef MAP_HUGETLB
2512 #define MAP_HUGETLB 0x40000
2513 #endif
2514 
2515 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2516 #ifndef MADV_HUGEPAGE
2517 #define MADV_HUGEPAGE 14
2518 #endif
2519 
2520 bool os::commit_memory(char* addr, size_t size, size_t alignment_hint,
2521                        bool exec) {
2522   if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) {
2523     int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2524     uintptr_t res =
2525       (uintptr_t) ::mmap(addr, size, prot,
2526                          MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_HUGETLB,
2527                          -1, 0);
2528     if (res != (uintptr_t) MAP_FAILED) {
2529       if (UseNUMAInterleaving) {
2530         numa_make_global(addr, size);
2531       }
2532       return true;
2533     }
2534     return false;
2535   }
2536 
2537   return commit_memory(addr, size, exec);




2538 }
2539 
2540 void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2541   if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) {
2542     // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2543     // be supported or the memory may already be backed by huge pages.
2544     ::madvise(addr, bytes, MADV_HUGEPAGE);
2545   }
2546 }
2547 
2548 void os::free_memory(char *addr, size_t bytes) {
2549   commit_memory(addr, bytes, false);
2550 }
2551 
2552 void os::numa_make_global(char *addr, size_t bytes) {
2553   Linux::numa_interleave_memory(addr, bytes);
2554 }
2555 
2556 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2557   Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2558 }
2559 
2560 bool os::numa_topology_changed()   { return false; }
2561 
2562 size_t os::numa_get_groups_num() {
2563   int max_node = Linux::numa_max_node();
2564   return max_node > 0 ? max_node + 1 : 1;
2565 }
2566 
2567 int os::numa_get_group_id() {
2568   int cpu_id = Linux::sched_getcpu();
2569   if (cpu_id != -1) {
2570     int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2571     if (lgrp_id != -1) {
2572       return lgrp_id;
2573     }
2574   }
2575   return 0;
2576 }
2577 
2578 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2579   for (size_t i = 0; i < size; i++) {
2580     ids[i] = i;
2581   }
2582   return size;
2583 }
2584 
2585 bool os::get_page_info(char *start, page_info* info) {
2586   return false;
2587 }
2588 
2589 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2590   return end;
2591 }
2592 
2593 
2594 int os::Linux::sched_getcpu_syscall(void) {
2595   unsigned int cpu;
2596   int retval = -1;
2597 
2598 #if defined(IA32)
2599 # ifndef SYS_getcpu
2600 # define SYS_getcpu 318
2601 # endif
2602   retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2603 #elif defined(AMD64)
2604 // Unfortunately we have to bring all these macros here from vsyscall.h
2605 // to be able to compile on old linuxes.
2606 # define __NR_vgetcpu 2
2607 # define VSYSCALL_START (-10UL << 20)
2608 # define VSYSCALL_SIZE 1024
2609 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2610   typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2611   vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2612   retval = vgetcpu(&cpu, NULL, NULL);
2613 #endif
2614 
2615   return (retval == -1) ? retval : cpu;
2616 }
2617 
2618 // Something to do with the numa-aware allocator needs these symbols
2619 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2620 extern "C" JNIEXPORT void numa_error(char *where) { }
2621 extern "C" JNIEXPORT int fork1() { return fork(); }
2622 
2623 
2624 // If we are running with libnuma version > 2, then we should
2625 // be trying to use symbols with versions 1.1
2626 // If we are running with earlier version, which did not have symbol versions,
2627 // we should use the base version.
2628 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2629   void *f = dlvsym(handle, name, "libnuma_1.1");
2630   if (f == NULL) {
2631     f = dlsym(handle, name);
2632   }
2633   return f;
2634 }
2635 
2636 bool os::Linux::libnuma_init() {
2637   // sched_getcpu() should be in libc.
2638   set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2639                                   dlsym(RTLD_DEFAULT, "sched_getcpu")));
2640 
2641   // If it's not, try a direct syscall.
2642   if (sched_getcpu() == -1)
2643     set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
2644 
2645   if (sched_getcpu() != -1) { // Does it work?
2646     void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2647     if (handle != NULL) {
2648       set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2649                                            libnuma_dlsym(handle, "numa_node_to_cpus")));
2650       set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2651                                        libnuma_dlsym(handle, "numa_max_node")));
2652       set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2653                                         libnuma_dlsym(handle, "numa_available")));
2654       set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2655                                             libnuma_dlsym(handle, "numa_tonode_memory")));
2656       set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2657                                             libnuma_dlsym(handle, "numa_interleave_memory")));
2658 
2659 
2660       if (numa_available() != -1) {
2661         set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2662         // Create a cpu -> node mapping
2663         _cpu_to_node = new (ResourceObj::C_HEAP) GrowableArray<int>(0, true);
2664         rebuild_cpu_to_node_map();
2665         return true;
2666       }
2667     }
2668   }
2669   return false;
2670 }
2671 
2672 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2673 // The table is later used in get_node_by_cpu().
2674 void os::Linux::rebuild_cpu_to_node_map() {
2675   const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2676                               // in libnuma (possible values are starting from 16,
2677                               // and continuing up with every other power of 2, but less
2678                               // than the maximum number of CPUs supported by kernel), and
2679                               // is a subject to change (in libnuma version 2 the requirements
2680                               // are more reasonable) we'll just hardcode the number they use
2681                               // in the library.
2682   const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2683 
2684   size_t cpu_num = os::active_processor_count();
2685   size_t cpu_map_size = NCPUS / BitsPerCLong;
2686   size_t cpu_map_valid_size =
2687     MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2688 
2689   cpu_to_node()->clear();
2690   cpu_to_node()->at_grow(cpu_num - 1);
2691   size_t node_num = numa_get_groups_num();
2692 
2693   unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size);
2694   for (size_t i = 0; i < node_num; i++) {
2695     if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2696       for (size_t j = 0; j < cpu_map_valid_size; j++) {
2697         if (cpu_map[j] != 0) {
2698           for (size_t k = 0; k < BitsPerCLong; k++) {
2699             if (cpu_map[j] & (1UL << k)) {
2700               cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2701             }
2702           }
2703         }
2704       }
2705     }
2706   }
2707   FREE_C_HEAP_ARRAY(unsigned long, cpu_map);
2708 }
2709 
2710 int os::Linux::get_node_by_cpu(int cpu_id) {
2711   if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2712     return cpu_to_node()->at(cpu_id);
2713   }
2714   return -1;
2715 }
2716 
2717 GrowableArray<int>* os::Linux::_cpu_to_node;
2718 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2719 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2720 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2721 os::Linux::numa_available_func_t os::Linux::_numa_available;
2722 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2723 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2724 unsigned long* os::Linux::_numa_all_nodes;
2725 
2726 bool os::uncommit_memory(char* addr, size_t size) {
2727   uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2728                 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2729   return res  != (uintptr_t) MAP_FAILED;
2730 }
2731 
2732 // Linux uses a growable mapping for the stack, and if the mapping for
2733 // the stack guard pages is not removed when we detach a thread the
2734 // stack cannot grow beyond the pages where the stack guard was
2735 // mapped.  If at some point later in the process the stack expands to
2736 // that point, the Linux kernel cannot expand the stack any further
2737 // because the guard pages are in the way, and a segfault occurs.
2738 //
2739 // However, it's essential not to split the stack region by unmapping
2740 // a region (leaving a hole) that's already part of the stack mapping,
2741 // so if the stack mapping has already grown beyond the guard pages at
2742 // the time we create them, we have to truncate the stack mapping.
2743 // So, we need to know the extent of the stack mapping when
2744 // create_stack_guard_pages() is called.
2745 
2746 // Find the bounds of the stack mapping.  Return true for success.
2747 //
2748 // We only need this for stacks that are growable: at the time of
2749 // writing thread stacks don't use growable mappings (i.e. those
2750 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
2751 // only applies to the main thread.
2752 
2753 static
2754 bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) {
2755 
2756   char buf[128];
2757   int fd, sz;
2758 
2759   if ((fd = ::open("/proc/self/maps", O_RDONLY)) < 0) {
2760     return false;
2761   }
2762 
2763   const char kw[] = "[stack]";
2764   const int kwlen = sizeof(kw)-1;
2765 
2766   // Address part of /proc/self/maps couldn't be more than 128 bytes
2767   while ((sz = os::get_line_chars(fd, buf, sizeof(buf))) > 0) {
2768      if (sz > kwlen && ::memcmp(buf+sz-kwlen, kw, kwlen) == 0) {
2769         // Extract addresses
2770         if (sscanf(buf, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) {
2771            uintptr_t sp = (uintptr_t) __builtin_frame_address(0);
2772            if (sp >= *bottom && sp <= *top) {
2773               ::close(fd);
2774               return true;
2775            }
2776         }
2777      }
2778   }
2779 
2780  ::close(fd);
2781   return false;
2782 }
2783 
2784 
2785 // If the (growable) stack mapping already extends beyond the point
2786 // where we're going to put our guard pages, truncate the mapping at
2787 // that point by munmap()ping it.  This ensures that when we later
2788 // munmap() the guard pages we don't leave a hole in the stack
2789 // mapping. This only affects the main/initial thread, but guard
2790 // against future OS changes
2791 bool os::create_stack_guard_pages(char* addr, size_t size) {
2792   uintptr_t stack_extent, stack_base;
2793   bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true);
2794   if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) {
2795       assert(os::Linux::is_initial_thread(),
2796            "growable stack in non-initial thread");
2797     if (stack_extent < (uintptr_t)addr)
2798       ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent);
2799   }
2800 
2801   return os::commit_memory(addr, size);
2802 }
2803 
2804 // If this is a growable mapping, remove the guard pages entirely by
2805 // munmap()ping them.  If not, just call uncommit_memory(). This only
2806 // affects the main/initial thread, but guard against future OS changes
2807 bool os::remove_stack_guard_pages(char* addr, size_t size) {
2808   uintptr_t stack_extent, stack_base;
2809   bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true);
2810   if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) {
2811       assert(os::Linux::is_initial_thread(),
2812            "growable stack in non-initial thread");
2813 
2814     return ::munmap(addr, size) == 0;
2815   }
2816 
2817   return os::uncommit_memory(addr, size);
2818 }
2819 
2820 static address _highest_vm_reserved_address = NULL;
2821 
2822 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
2823 // at 'requested_addr'. If there are existing memory mappings at the same
2824 // location, however, they will be overwritten. If 'fixed' is false,
2825 // 'requested_addr' is only treated as a hint, the return value may or
2826 // may not start from the requested address. Unlike Linux mmap(), this
2827 // function returns NULL to indicate failure.
2828 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
2829   char * addr;
2830   int flags;
2831 
2832   flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
2833   if (fixed) {
2834     assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
2835     flags |= MAP_FIXED;
2836   }
2837 
2838   // Map uncommitted pages PROT_READ and PROT_WRITE, change access
2839   // to PROT_EXEC if executable when we commit the page.
2840   addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE,
2841                        flags, -1, 0);
2842 
2843   if (addr != MAP_FAILED) {
2844     // anon_mmap() should only get called during VM initialization,
2845     // don't need lock (actually we can skip locking even it can be called
2846     // from multiple threads, because _highest_vm_reserved_address is just a
2847     // hint about the upper limit of non-stack memory regions.)
2848     if ((address)addr + bytes > _highest_vm_reserved_address) {
2849       _highest_vm_reserved_address = (address)addr + bytes;
2850     }
2851   }
2852 
2853   return addr == MAP_FAILED ? NULL : addr;
2854 }
2855 
2856 // Don't update _highest_vm_reserved_address, because there might be memory
2857 // regions above addr + size. If so, releasing a memory region only creates
2858 // a hole in the address space, it doesn't help prevent heap-stack collision.
2859 //
2860 static int anon_munmap(char * addr, size_t size) {
2861   return ::munmap(addr, size) == 0;
2862 }
2863 
2864 char* os::reserve_memory(size_t bytes, char* requested_addr,
2865                          size_t alignment_hint) {
2866   return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
2867 }
2868 
2869 bool os::release_memory(char* addr, size_t size) {
2870   return anon_munmap(addr, size);
2871 }
2872 
2873 static address highest_vm_reserved_address() {
2874   return _highest_vm_reserved_address;
2875 }
2876 
2877 static bool linux_mprotect(char* addr, size_t size, int prot) {
2878   // Linux wants the mprotect address argument to be page aligned.
2879   char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
2880 
2881   // According to SUSv3, mprotect() should only be used with mappings
2882   // established by mmap(), and mmap() always maps whole pages. Unaligned
2883   // 'addr' likely indicates problem in the VM (e.g. trying to change
2884   // protection of malloc'ed or statically allocated memory). Check the
2885   // caller if you hit this assert.
2886   assert(addr == bottom, "sanity check");
2887 
2888   size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
2889   return ::mprotect(bottom, size, prot) == 0;
2890 }
2891 
2892 // Set protections specified
2893 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
2894                         bool is_committed) {
2895   unsigned int p = 0;
2896   switch (prot) {
2897   case MEM_PROT_NONE: p = PROT_NONE; break;
2898   case MEM_PROT_READ: p = PROT_READ; break;
2899   case MEM_PROT_RW:   p = PROT_READ|PROT_WRITE; break;
2900   case MEM_PROT_RWX:  p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
2901   default:
2902     ShouldNotReachHere();
2903   }
2904   // is_committed is unused.
2905   return linux_mprotect(addr, bytes, p);
2906 }
2907 
2908 bool os::guard_memory(char* addr, size_t size) {
2909   return linux_mprotect(addr, size, PROT_NONE);
2910 }
2911 
2912 bool os::unguard_memory(char* addr, size_t size) {
2913   return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
2914 }
2915 
2916 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
2917   bool result = false;
2918   void *p = mmap (NULL, page_size, PROT_READ|PROT_WRITE,
2919                   MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
2920                   -1, 0);
2921 
2922   if (p != (void *) -1) {
2923     // We don't know if this really is a huge page or not.
2924     FILE *fp = fopen("/proc/self/maps", "r");
2925     if (fp) {
2926       while (!feof(fp)) {
2927         char chars[257];
2928         long x = 0;
2929         if (fgets(chars, sizeof(chars), fp)) {
2930           if (sscanf(chars, "%lx-%*x", &x) == 1
2931               && x == (long)p) {
2932             if (strstr (chars, "hugepage")) {
2933               result = true;
2934               break;
2935             }
2936           }
2937         }
2938       }
2939       fclose(fp);
2940     }
2941     munmap (p, page_size);
2942     if (result)
2943       return true;
2944   }
2945 
2946   if (warn) {
2947     warning("HugeTLBFS is not supported by the operating system.");
2948   }
2949 
2950   return result;
2951 }
2952 
2953 /*
2954 * Set the coredump_filter bits to include largepages in core dump (bit 6)
2955 *
2956 * From the coredump_filter documentation:
2957 *
2958 * - (bit 0) anonymous private memory
2959 * - (bit 1) anonymous shared memory
2960 * - (bit 2) file-backed private memory
2961 * - (bit 3) file-backed shared memory
2962 * - (bit 4) ELF header pages in file-backed private memory areas (it is
2963 *           effective only if the bit 2 is cleared)
2964 * - (bit 5) hugetlb private memory
2965 * - (bit 6) hugetlb shared memory
2966 */
2967 static void set_coredump_filter(void) {
2968   FILE *f;
2969   long cdm;
2970 
2971   if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
2972     return;
2973   }
2974 
2975   if (fscanf(f, "%lx", &cdm) != 1) {
2976     fclose(f);
2977     return;
2978   }
2979 
2980   rewind(f);
2981 
2982   if ((cdm & LARGEPAGES_BIT) == 0) {
2983     cdm |= LARGEPAGES_BIT;
2984     fprintf(f, "%#lx", cdm);
2985   }
2986 
2987   fclose(f);
2988 }
2989 
2990 // Large page support
2991 
2992 static size_t _large_page_size = 0;
2993 
2994 void os::large_page_init() {
2995   if (!UseLargePages) {
2996     UseHugeTLBFS = false;
2997     UseSHM = false;
2998     return;
2999   }
3000 
3001   if (FLAG_IS_DEFAULT(UseHugeTLBFS) && FLAG_IS_DEFAULT(UseSHM)) {
3002     // If UseLargePages is specified on the command line try both methods,
3003     // if it's default, then try only HugeTLBFS.
3004     if (FLAG_IS_DEFAULT(UseLargePages)) {
3005       UseHugeTLBFS = true;
3006     } else {
3007       UseHugeTLBFS = UseSHM = true;
3008     }
3009   }
3010 
3011   if (LargePageSizeInBytes) {
3012     _large_page_size = LargePageSizeInBytes;
3013   } else {
3014     // large_page_size on Linux is used to round up heap size. x86 uses either
3015     // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3016     // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3017     // page as large as 256M.
3018     //
3019     // Here we try to figure out page size by parsing /proc/meminfo and looking
3020     // for a line with the following format:
3021     //    Hugepagesize:     2048 kB
3022     //
3023     // If we can't determine the value (e.g. /proc is not mounted, or the text
3024     // format has been changed), we'll use the largest page size supported by
3025     // the processor.
3026 
3027 #ifndef ZERO
3028     _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3029                        ARM_ONLY(2 * M) PPC_ONLY(4 * M);
3030 #endif // ZERO
3031 
3032     FILE *fp = fopen("/proc/meminfo", "r");
3033     if (fp) {
3034       while (!feof(fp)) {
3035         int x = 0;
3036         char buf[16];
3037         if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3038           if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3039             _large_page_size = x * K;
3040             break;
3041           }
3042         } else {
3043           // skip to next line
3044           for (;;) {
3045             int ch = fgetc(fp);
3046             if (ch == EOF || ch == (int)'\n') break;
3047           }
3048         }
3049       }
3050       fclose(fp);
3051     }
3052   }
3053 
3054   // print a warning if any large page related flag is specified on command line
3055   bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3056 
3057   const size_t default_page_size = (size_t)Linux::page_size();
3058   if (_large_page_size > default_page_size) {
3059     _page_sizes[0] = _large_page_size;
3060     _page_sizes[1] = default_page_size;
3061     _page_sizes[2] = 0;
3062   }
3063   UseHugeTLBFS = UseHugeTLBFS &&
3064                  Linux::hugetlbfs_sanity_check(warn_on_failure, _large_page_size);
3065 
3066   if (UseHugeTLBFS)
3067     UseSHM = false;
3068 
3069   UseLargePages = UseHugeTLBFS || UseSHM;
3070 
3071   set_coredump_filter();
3072 }
3073 
3074 #ifndef SHM_HUGETLB
3075 #define SHM_HUGETLB 04000
3076 #endif
3077 
3078 char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) {
3079   // "exec" is passed in but not used.  Creating the shared image for
3080   // the code cache doesn't have an SHM_X executable permission to check.
3081   assert(UseLargePages && UseSHM, "only for SHM large pages");
3082 
3083   key_t key = IPC_PRIVATE;
3084   char *addr;
3085 
3086   bool warn_on_failure = UseLargePages &&
3087                         (!FLAG_IS_DEFAULT(UseLargePages) ||
3088                          !FLAG_IS_DEFAULT(LargePageSizeInBytes)
3089                         );
3090   char msg[128];
3091 
3092   // Create a large shared memory region to attach to based on size.
3093   // Currently, size is the total size of the heap
3094   int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3095   if (shmid == -1) {
3096      // Possible reasons for shmget failure:
3097      // 1. shmmax is too small for Java heap.
3098      //    > check shmmax value: cat /proc/sys/kernel/shmmax
3099      //    > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3100      // 2. not enough large page memory.
3101      //    > check available large pages: cat /proc/meminfo
3102      //    > increase amount of large pages:
3103      //          echo new_value > /proc/sys/vm/nr_hugepages
3104      //      Note 1: different Linux may use different name for this property,
3105      //            e.g. on Redhat AS-3 it is "hugetlb_pool".
3106      //      Note 2: it's possible there's enough physical memory available but
3107      //            they are so fragmented after a long run that they can't
3108      //            coalesce into large pages. Try to reserve large pages when
3109      //            the system is still "fresh".
3110      if (warn_on_failure) {
3111        jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3112        warning(msg);
3113      }
3114      return NULL;
3115   }
3116 
3117   // attach to the region
3118   addr = (char*)shmat(shmid, req_addr, 0);
3119   int err = errno;
3120 
3121   // Remove shmid. If shmat() is successful, the actual shared memory segment
3122   // will be deleted when it's detached by shmdt() or when the process
3123   // terminates. If shmat() is not successful this will remove the shared
3124   // segment immediately.
3125   shmctl(shmid, IPC_RMID, NULL);
3126 
3127   if ((intptr_t)addr == -1) {
3128      if (warn_on_failure) {
3129        jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3130        warning(msg);
3131      }
3132      return NULL;
3133   }
3134 
3135   if ((addr != NULL) && UseNUMAInterleaving) {
3136     numa_make_global(addr, bytes);
3137   }
3138 
3139   return addr;
3140 }
3141 
3142 bool os::release_memory_special(char* base, size_t bytes) {
3143   // detaching the SHM segment will also delete it, see reserve_memory_special()
3144   int rslt = shmdt(base);
3145   return rslt == 0;
3146 }
3147 
3148 size_t os::large_page_size() {
3149   return _large_page_size;
3150 }
3151 
3152 // HugeTLBFS allows application to commit large page memory on demand;
3153 // with SysV SHM the entire memory region must be allocated as shared
3154 // memory.
3155 bool os::can_commit_large_page_memory() {
3156   return UseHugeTLBFS;
3157 }
3158 
3159 bool os::can_execute_large_page_memory() {
3160   return UseHugeTLBFS;
3161 }
3162 
3163 // Reserve memory at an arbitrary address, only if that area is
3164 // available (and not reserved for something else).
3165 
3166 char* os::attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3167   const int max_tries = 10;
3168   char* base[max_tries];
3169   size_t size[max_tries];
3170   const size_t gap = 0x000000;
3171 
3172   // Assert only that the size is a multiple of the page size, since
3173   // that's all that mmap requires, and since that's all we really know
3174   // about at this low abstraction level.  If we need higher alignment,
3175   // we can either pass an alignment to this method or verify alignment
3176   // in one of the methods further up the call chain.  See bug 5044738.
3177   assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3178 
3179   // Repeatedly allocate blocks until the block is allocated at the
3180   // right spot. Give up after max_tries. Note that reserve_memory() will
3181   // automatically update _highest_vm_reserved_address if the call is
3182   // successful. The variable tracks the highest memory address every reserved
3183   // by JVM. It is used to detect heap-stack collision if running with
3184   // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3185   // space than needed, it could confuse the collision detecting code. To
3186   // solve the problem, save current _highest_vm_reserved_address and
3187   // calculate the correct value before return.
3188   address old_highest = _highest_vm_reserved_address;
3189 
3190   // Linux mmap allows caller to pass an address as hint; give it a try first,
3191   // if kernel honors the hint then we can return immediately.
3192   char * addr = anon_mmap(requested_addr, bytes, false);
3193   if (addr == requested_addr) {
3194      return requested_addr;
3195   }
3196 
3197   if (addr != NULL) {
3198      // mmap() is successful but it fails to reserve at the requested address
3199      anon_munmap(addr, bytes);
3200   }
3201 
3202   int i;
3203   for (i = 0; i < max_tries; ++i) {
3204     base[i] = reserve_memory(bytes);
3205 
3206     if (base[i] != NULL) {
3207       // Is this the block we wanted?
3208       if (base[i] == requested_addr) {
3209         size[i] = bytes;
3210         break;
3211       }
3212 
3213       // Does this overlap the block we wanted? Give back the overlapped
3214       // parts and try again.
3215 
3216       size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3217       if (top_overlap >= 0 && top_overlap < bytes) {
3218         unmap_memory(base[i], top_overlap);
3219         base[i] += top_overlap;
3220         size[i] = bytes - top_overlap;
3221       } else {
3222         size_t bottom_overlap = base[i] + bytes - requested_addr;
3223         if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3224           unmap_memory(requested_addr, bottom_overlap);
3225           size[i] = bytes - bottom_overlap;
3226         } else {
3227           size[i] = bytes;
3228         }
3229       }
3230     }
3231   }
3232 
3233   // Give back the unused reserved pieces.
3234 
3235   for (int j = 0; j < i; ++j) {
3236     if (base[j] != NULL) {
3237       unmap_memory(base[j], size[j]);
3238     }
3239   }
3240 
3241   if (i < max_tries) {
3242     _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3243     return requested_addr;
3244   } else {
3245     _highest_vm_reserved_address = old_highest;
3246     return NULL;
3247   }
3248 }
3249 
3250 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3251   return ::read(fd, buf, nBytes);
3252 }
3253 
3254 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation.
3255 // Solaris uses poll(), linux uses park().
3256 // Poll() is likely a better choice, assuming that Thread.interrupt()
3257 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with
3258 // SIGSEGV, see 4355769.
3259 
3260 const int NANOSECS_PER_MILLISECS = 1000000;
3261 
3262 int os::sleep(Thread* thread, jlong millis, bool interruptible) {
3263   assert(thread == Thread::current(),  "thread consistency check");
3264 
3265   ParkEvent * const slp = thread->_SleepEvent ;
3266   slp->reset() ;
3267   OrderAccess::fence() ;
3268 
3269   if (interruptible) {
3270     jlong prevtime = javaTimeNanos();
3271 
3272     for (;;) {
3273       if (os::is_interrupted(thread, true)) {
3274         return OS_INTRPT;
3275       }
3276 
3277       jlong newtime = javaTimeNanos();
3278 
3279       if (newtime - prevtime < 0) {
3280         // time moving backwards, should only happen if no monotonic clock
3281         // not a guarantee() because JVM should not abort on kernel/glibc bugs
3282         assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3283       } else {
3284         millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS;
3285       }
3286 
3287       if(millis <= 0) {
3288         return OS_OK;
3289       }
3290 
3291       prevtime = newtime;
3292 
3293       {
3294         assert(thread->is_Java_thread(), "sanity check");
3295         JavaThread *jt = (JavaThread *) thread;
3296         ThreadBlockInVM tbivm(jt);
3297         OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
3298 
3299         jt->set_suspend_equivalent();
3300         // cleared by handle_special_suspend_equivalent_condition() or
3301         // java_suspend_self() via check_and_wait_while_suspended()
3302 
3303         slp->park(millis);
3304 
3305         // were we externally suspended while we were waiting?
3306         jt->check_and_wait_while_suspended();
3307       }
3308     }
3309   } else {
3310     OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
3311     jlong prevtime = javaTimeNanos();
3312 
3313     for (;;) {
3314       // It'd be nice to avoid the back-to-back javaTimeNanos() calls on
3315       // the 1st iteration ...
3316       jlong newtime = javaTimeNanos();
3317 
3318       if (newtime - prevtime < 0) {
3319         // time moving backwards, should only happen if no monotonic clock
3320         // not a guarantee() because JVM should not abort on kernel/glibc bugs
3321         assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3322       } else {
3323         millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS;
3324       }
3325 
3326       if(millis <= 0) break ;
3327 
3328       prevtime = newtime;
3329       slp->park(millis);
3330     }
3331     return OS_OK ;
3332   }
3333 }
3334 
3335 int os::naked_sleep() {
3336   // %% make the sleep time an integer flag. for now use 1 millisec.
3337   return os::sleep(Thread::current(), 1, false);
3338 }
3339 
3340 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3341 void os::infinite_sleep() {
3342   while (true) {    // sleep forever ...
3343     ::sleep(100);   // ... 100 seconds at a time
3344   }
3345 }
3346 
3347 // Used to convert frequent JVM_Yield() to nops
3348 bool os::dont_yield() {
3349   return DontYieldALot;
3350 }
3351 
3352 void os::yield() {
3353   sched_yield();
3354 }
3355 
3356 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
3357 
3358 void os::yield_all(int attempts) {
3359   // Yields to all threads, including threads with lower priorities
3360   // Threads on Linux are all with same priority. The Solaris style
3361   // os::yield_all() with nanosleep(1ms) is not necessary.
3362   sched_yield();
3363 }
3364 
3365 // Called from the tight loops to possibly influence time-sharing heuristics
3366 void os::loop_breaker(int attempts) {
3367   os::yield_all(attempts);
3368 }
3369 
3370 ////////////////////////////////////////////////////////////////////////////////
3371 // thread priority support
3372 
3373 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3374 // only supports dynamic priority, static priority must be zero. For real-time
3375 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3376 // However, for large multi-threaded applications, SCHED_RR is not only slower
3377 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3378 // of 5 runs - Sep 2005).
3379 //
3380 // The following code actually changes the niceness of kernel-thread/LWP. It
3381 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3382 // not the entire user process, and user level threads are 1:1 mapped to kernel
3383 // threads. It has always been the case, but could change in the future. For
3384 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3385 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3386 
3387 int os::java_to_os_priority[MaxPriority + 1] = {
3388   19,              // 0 Entry should never be used
3389 
3390    4,              // 1 MinPriority
3391    3,              // 2
3392    2,              // 3
3393 
3394    1,              // 4
3395    0,              // 5 NormPriority
3396   -1,              // 6
3397 
3398   -2,              // 7
3399   -3,              // 8
3400   -4,              // 9 NearMaxPriority
3401 
3402   -5               // 10 MaxPriority
3403 };
3404 
3405 static int prio_init() {
3406   if (ThreadPriorityPolicy == 1) {
3407     // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3408     // if effective uid is not root. Perhaps, a more elegant way of doing
3409     // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3410     if (geteuid() != 0) {
3411       if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3412         warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3413       }
3414       ThreadPriorityPolicy = 0;
3415     }
3416   }
3417   return 0;
3418 }
3419 
3420 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3421   if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
3422 
3423   int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3424   return (ret == 0) ? OS_OK : OS_ERR;
3425 }
3426 
3427 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
3428   if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
3429     *priority_ptr = java_to_os_priority[NormPriority];
3430     return OS_OK;
3431   }
3432 
3433   errno = 0;
3434   *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3435   return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3436 }
3437 
3438 // Hint to the underlying OS that a task switch would not be good.
3439 // Void return because it's a hint and can fail.
3440 void os::hint_no_preempt() {}
3441 
3442 ////////////////////////////////////////////////////////////////////////////////
3443 // suspend/resume support
3444 
3445 //  the low-level signal-based suspend/resume support is a remnant from the
3446 //  old VM-suspension that used to be for java-suspension, safepoints etc,
3447 //  within hotspot. Now there is a single use-case for this:
3448 //    - calling get_thread_pc() on the VMThread by the flat-profiler task
3449 //      that runs in the watcher thread.
3450 //  The remaining code is greatly simplified from the more general suspension
3451 //  code that used to be used.
3452 //
3453 //  The protocol is quite simple:
3454 //  - suspend:
3455 //      - sends a signal to the target thread
3456 //      - polls the suspend state of the osthread using a yield loop
3457 //      - target thread signal handler (SR_handler) sets suspend state
3458 //        and blocks in sigsuspend until continued
3459 //  - resume:
3460 //      - sets target osthread state to continue
3461 //      - sends signal to end the sigsuspend loop in the SR_handler
3462 //
3463 //  Note that the SR_lock plays no role in this suspend/resume protocol.
3464 //
3465 
3466 static void resume_clear_context(OSThread *osthread) {
3467   osthread->set_ucontext(NULL);
3468   osthread->set_siginfo(NULL);
3469 
3470   // notify the suspend action is completed, we have now resumed
3471   osthread->sr.clear_suspended();
3472 }
3473 
3474 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
3475   osthread->set_ucontext(context);
3476   osthread->set_siginfo(siginfo);
3477 }
3478 
3479 //
3480 // Handler function invoked when a thread's execution is suspended or
3481 // resumed. We have to be careful that only async-safe functions are
3482 // called here (Note: most pthread functions are not async safe and
3483 // should be avoided.)
3484 //
3485 // Note: sigwait() is a more natural fit than sigsuspend() from an
3486 // interface point of view, but sigwait() prevents the signal hander
3487 // from being run. libpthread would get very confused by not having
3488 // its signal handlers run and prevents sigwait()'s use with the
3489 // mutex granting granting signal.
3490 //
3491 // Currently only ever called on the VMThread
3492 //
3493 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3494   // Save and restore errno to avoid confusing native code with EINTR
3495   // after sigsuspend.
3496   int old_errno = errno;
3497 
3498   Thread* thread = Thread::current();
3499   OSThread* osthread = thread->osthread();
3500   assert(thread->is_VM_thread(), "Must be VMThread");
3501   // read current suspend action
3502   int action = osthread->sr.suspend_action();
3503   if (action == SR_SUSPEND) {
3504     suspend_save_context(osthread, siginfo, context);
3505 
3506     // Notify the suspend action is about to be completed. do_suspend()
3507     // waits until SR_SUSPENDED is set and then returns. We will wait
3508     // here for a resume signal and that completes the suspend-other
3509     // action. do_suspend/do_resume is always called as a pair from
3510     // the same thread - so there are no races
3511 
3512     // notify the caller
3513     osthread->sr.set_suspended();
3514 
3515     sigset_t suspend_set;  // signals for sigsuspend()
3516 
3517     // get current set of blocked signals and unblock resume signal
3518     pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3519     sigdelset(&suspend_set, SR_signum);
3520 
3521     // wait here until we are resumed
3522     do {
3523       sigsuspend(&suspend_set);
3524       // ignore all returns until we get a resume signal
3525     } while (osthread->sr.suspend_action() != SR_CONTINUE);
3526 
3527     resume_clear_context(osthread);
3528 
3529   } else {
3530     assert(action == SR_CONTINUE, "unexpected sr action");
3531     // nothing special to do - just leave the handler
3532   }
3533 
3534   errno = old_errno;
3535 }
3536 
3537 
3538 static int SR_initialize() {
3539   struct sigaction act;
3540   char *s;
3541   /* Get signal number to use for suspend/resume */
3542   if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
3543     int sig = ::strtol(s, 0, 10);
3544     if (sig > 0 || sig < _NSIG) {
3545         SR_signum = sig;
3546     }
3547   }
3548 
3549   assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
3550         "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
3551 
3552   sigemptyset(&SR_sigset);
3553   sigaddset(&SR_sigset, SR_signum);
3554 
3555   /* Set up signal handler for suspend/resume */
3556   act.sa_flags = SA_RESTART|SA_SIGINFO;
3557   act.sa_handler = (void (*)(int)) SR_handler;
3558 
3559   // SR_signum is blocked by default.
3560   // 4528190 - We also need to block pthread restart signal (32 on all
3561   // supported Linux platforms). Note that LinuxThreads need to block
3562   // this signal for all threads to work properly. So we don't have
3563   // to use hard-coded signal number when setting up the mask.
3564   pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
3565 
3566   if (sigaction(SR_signum, &act, 0) == -1) {
3567     return -1;
3568   }
3569 
3570   // Save signal flag
3571   os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
3572   return 0;
3573 }
3574 
3575 static int SR_finalize() {
3576   return 0;
3577 }
3578 
3579 
3580 // returns true on success and false on error - really an error is fatal
3581 // but this seems the normal response to library errors
3582 static bool do_suspend(OSThread* osthread) {
3583   // mark as suspended and send signal
3584   osthread->sr.set_suspend_action(SR_SUSPEND);
3585   int status = pthread_kill(osthread->pthread_id(), SR_signum);
3586   assert_status(status == 0, status, "pthread_kill");
3587 
3588   // check status and wait until notified of suspension
3589   if (status == 0) {
3590     for (int i = 0; !osthread->sr.is_suspended(); i++) {
3591       os::yield_all(i);
3592     }
3593     osthread->sr.set_suspend_action(SR_NONE);
3594     return true;
3595   }
3596   else {
3597     osthread->sr.set_suspend_action(SR_NONE);
3598     return false;
3599   }
3600 }
3601 
3602 static void do_resume(OSThread* osthread) {
3603   assert(osthread->sr.is_suspended(), "thread should be suspended");
3604   osthread->sr.set_suspend_action(SR_CONTINUE);
3605 
3606   int status = pthread_kill(osthread->pthread_id(), SR_signum);
3607   assert_status(status == 0, status, "pthread_kill");
3608   // check status and wait unit notified of resumption
3609   if (status == 0) {
3610     for (int i = 0; osthread->sr.is_suspended(); i++) {
3611       os::yield_all(i);
3612     }
3613   }
3614   osthread->sr.set_suspend_action(SR_NONE);
3615 }
3616 
3617 ////////////////////////////////////////////////////////////////////////////////
3618 // interrupt support
3619 
3620 void os::interrupt(Thread* thread) {
3621   assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3622     "possibility of dangling Thread pointer");
3623 
3624   OSThread* osthread = thread->osthread();
3625 
3626   if (!osthread->interrupted()) {
3627     osthread->set_interrupted(true);
3628     // More than one thread can get here with the same value of osthread,
3629     // resulting in multiple notifications.  We do, however, want the store
3630     // to interrupted() to be visible to other threads before we execute unpark().
3631     OrderAccess::fence();
3632     ParkEvent * const slp = thread->_SleepEvent ;
3633     if (slp != NULL) slp->unpark() ;
3634   }
3635 
3636   // For JSR166. Unpark even if interrupt status already was set
3637   if (thread->is_Java_thread())
3638     ((JavaThread*)thread)->parker()->unpark();
3639 
3640   ParkEvent * ev = thread->_ParkEvent ;
3641   if (ev != NULL) ev->unpark() ;
3642 
3643 }
3644 
3645 bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
3646   assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3647     "possibility of dangling Thread pointer");
3648 
3649   OSThread* osthread = thread->osthread();
3650 
3651   bool interrupted = osthread->interrupted();
3652 
3653   if (interrupted && clear_interrupted) {
3654     osthread->set_interrupted(false);
3655     // consider thread->_SleepEvent->reset() ... optional optimization
3656   }
3657 
3658   return interrupted;
3659 }
3660 
3661 ///////////////////////////////////////////////////////////////////////////////////
3662 // signal handling (except suspend/resume)
3663 
3664 // This routine may be used by user applications as a "hook" to catch signals.
3665 // The user-defined signal handler must pass unrecognized signals to this
3666 // routine, and if it returns true (non-zero), then the signal handler must
3667 // return immediately.  If the flag "abort_if_unrecognized" is true, then this
3668 // routine will never retun false (zero), but instead will execute a VM panic
3669 // routine kill the process.
3670 //
3671 // If this routine returns false, it is OK to call it again.  This allows
3672 // the user-defined signal handler to perform checks either before or after
3673 // the VM performs its own checks.  Naturally, the user code would be making
3674 // a serious error if it tried to handle an exception (such as a null check
3675 // or breakpoint) that the VM was generating for its own correct operation.
3676 //
3677 // This routine may recognize any of the following kinds of signals:
3678 //    SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
3679 // It should be consulted by handlers for any of those signals.
3680 //
3681 // The caller of this routine must pass in the three arguments supplied
3682 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
3683 // field of the structure passed to sigaction().  This routine assumes that
3684 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
3685 //
3686 // Note that the VM will print warnings if it detects conflicting signal
3687 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
3688 //
3689 extern "C" JNIEXPORT int
3690 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
3691                         void* ucontext, int abort_if_unrecognized);
3692 
3693 void signalHandler(int sig, siginfo_t* info, void* uc) {
3694   assert(info != NULL && uc != NULL, "it must be old kernel");
3695   JVM_handle_linux_signal(sig, info, uc, true);
3696 }
3697 
3698 
3699 // This boolean allows users to forward their own non-matching signals
3700 // to JVM_handle_linux_signal, harmlessly.
3701 bool os::Linux::signal_handlers_are_installed = false;
3702 
3703 // For signal-chaining
3704 struct sigaction os::Linux::sigact[MAXSIGNUM];
3705 unsigned int os::Linux::sigs = 0;
3706 bool os::Linux::libjsig_is_loaded = false;
3707 typedef struct sigaction *(*get_signal_t)(int);
3708 get_signal_t os::Linux::get_signal_action = NULL;
3709 
3710 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
3711   struct sigaction *actp = NULL;
3712 
3713   if (libjsig_is_loaded) {
3714     // Retrieve the old signal handler from libjsig
3715     actp = (*get_signal_action)(sig);
3716   }
3717   if (actp == NULL) {
3718     // Retrieve the preinstalled signal handler from jvm
3719     actp = get_preinstalled_handler(sig);
3720   }
3721 
3722   return actp;
3723 }
3724 
3725 static bool call_chained_handler(struct sigaction *actp, int sig,
3726                                  siginfo_t *siginfo, void *context) {
3727   // Call the old signal handler
3728   if (actp->sa_handler == SIG_DFL) {
3729     // It's more reasonable to let jvm treat it as an unexpected exception
3730     // instead of taking the default action.
3731     return false;
3732   } else if (actp->sa_handler != SIG_IGN) {
3733     if ((actp->sa_flags & SA_NODEFER) == 0) {
3734       // automaticlly block the signal
3735       sigaddset(&(actp->sa_mask), sig);
3736     }
3737 
3738     sa_handler_t hand;
3739     sa_sigaction_t sa;
3740     bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
3741     // retrieve the chained handler
3742     if (siginfo_flag_set) {
3743       sa = actp->sa_sigaction;
3744     } else {
3745       hand = actp->sa_handler;
3746     }
3747 
3748     if ((actp->sa_flags & SA_RESETHAND) != 0) {
3749       actp->sa_handler = SIG_DFL;
3750     }
3751 
3752     // try to honor the signal mask
3753     sigset_t oset;
3754     pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
3755 
3756     // call into the chained handler
3757     if (siginfo_flag_set) {
3758       (*sa)(sig, siginfo, context);
3759     } else {
3760       (*hand)(sig);
3761     }
3762 
3763     // restore the signal mask
3764     pthread_sigmask(SIG_SETMASK, &oset, 0);
3765   }
3766   // Tell jvm's signal handler the signal is taken care of.
3767   return true;
3768 }
3769 
3770 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
3771   bool chained = false;
3772   // signal-chaining
3773   if (UseSignalChaining) {
3774     struct sigaction *actp = get_chained_signal_action(sig);
3775     if (actp != NULL) {
3776       chained = call_chained_handler(actp, sig, siginfo, context);
3777     }
3778   }
3779   return chained;
3780 }
3781 
3782 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
3783   if ((( (unsigned int)1 << sig ) & sigs) != 0) {
3784     return &sigact[sig];
3785   }
3786   return NULL;
3787 }
3788 
3789 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
3790   assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3791   sigact[sig] = oldAct;
3792   sigs |= (unsigned int)1 << sig;
3793 }
3794 
3795 // for diagnostic
3796 int os::Linux::sigflags[MAXSIGNUM];
3797 
3798 int os::Linux::get_our_sigflags(int sig) {
3799   assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3800   return sigflags[sig];
3801 }
3802 
3803 void os::Linux::set_our_sigflags(int sig, int flags) {
3804   assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3805   sigflags[sig] = flags;
3806 }
3807 
3808 void os::Linux::set_signal_handler(int sig, bool set_installed) {
3809   // Check for overwrite.
3810   struct sigaction oldAct;
3811   sigaction(sig, (struct sigaction*)NULL, &oldAct);
3812 
3813   void* oldhand = oldAct.sa_sigaction
3814                 ? CAST_FROM_FN_PTR(void*,  oldAct.sa_sigaction)
3815                 : CAST_FROM_FN_PTR(void*,  oldAct.sa_handler);
3816   if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
3817       oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
3818       oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
3819     if (AllowUserSignalHandlers || !set_installed) {
3820       // Do not overwrite; user takes responsibility to forward to us.
3821       return;
3822     } else if (UseSignalChaining) {
3823       // save the old handler in jvm
3824       save_preinstalled_handler(sig, oldAct);
3825       // libjsig also interposes the sigaction() call below and saves the
3826       // old sigaction on it own.
3827     } else {
3828       fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
3829                     "%#lx for signal %d.", (long)oldhand, sig));
3830     }
3831   }
3832 
3833   struct sigaction sigAct;
3834   sigfillset(&(sigAct.sa_mask));
3835   sigAct.sa_handler = SIG_DFL;
3836   if (!set_installed) {
3837     sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3838   } else {
3839     sigAct.sa_sigaction = signalHandler;
3840     sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3841   }
3842   // Save flags, which are set by ours
3843   assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3844   sigflags[sig] = sigAct.sa_flags;
3845 
3846   int ret = sigaction(sig, &sigAct, &oldAct);
3847   assert(ret == 0, "check");
3848 
3849   void* oldhand2  = oldAct.sa_sigaction
3850                   ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
3851                   : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
3852   assert(oldhand2 == oldhand, "no concurrent signal handler installation");
3853 }
3854 
3855 // install signal handlers for signals that HotSpot needs to
3856 // handle in order to support Java-level exception handling.
3857 
3858 void os::Linux::install_signal_handlers() {
3859   if (!signal_handlers_are_installed) {
3860     signal_handlers_are_installed = true;
3861 
3862     // signal-chaining
3863     typedef void (*signal_setting_t)();
3864     signal_setting_t begin_signal_setting = NULL;
3865     signal_setting_t end_signal_setting = NULL;
3866     begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3867                              dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
3868     if (begin_signal_setting != NULL) {
3869       end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3870                              dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
3871       get_signal_action = CAST_TO_FN_PTR(get_signal_t,
3872                             dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
3873       libjsig_is_loaded = true;
3874       assert(UseSignalChaining, "should enable signal-chaining");
3875     }
3876     if (libjsig_is_loaded) {
3877       // Tell libjsig jvm is setting signal handlers
3878       (*begin_signal_setting)();
3879     }
3880 
3881     set_signal_handler(SIGSEGV, true);
3882     set_signal_handler(SIGPIPE, true);
3883     set_signal_handler(SIGBUS, true);
3884     set_signal_handler(SIGILL, true);
3885     set_signal_handler(SIGFPE, true);
3886     set_signal_handler(SIGXFSZ, true);
3887 
3888     if (libjsig_is_loaded) {
3889       // Tell libjsig jvm finishes setting signal handlers
3890       (*end_signal_setting)();
3891     }
3892 
3893     // We don't activate signal checker if libjsig is in place, we trust ourselves
3894     // and if UserSignalHandler is installed all bets are off
3895     if (CheckJNICalls) {
3896       if (libjsig_is_loaded) {
3897         tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
3898         check_signals = false;
3899       }
3900       if (AllowUserSignalHandlers) {
3901         tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
3902         check_signals = false;
3903       }
3904     }
3905   }
3906 }
3907 
3908 // This is the fastest way to get thread cpu time on Linux.
3909 // Returns cpu time (user+sys) for any thread, not only for current.
3910 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
3911 // It might work on 2.6.10+ with a special kernel/glibc patch.
3912 // For reference, please, see IEEE Std 1003.1-2004:
3913 //   http://www.unix.org/single_unix_specification
3914 
3915 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
3916   struct timespec tp;
3917   int rc = os::Linux::clock_gettime(clockid, &tp);
3918   assert(rc == 0, "clock_gettime is expected to return 0 code");
3919 
3920   return (tp.tv_sec * SEC_IN_NANOSECS) + tp.tv_nsec;
3921 }
3922 
3923 /////
3924 // glibc on Linux platform uses non-documented flag
3925 // to indicate, that some special sort of signal
3926 // trampoline is used.
3927 // We will never set this flag, and we should
3928 // ignore this flag in our diagnostic
3929 #ifdef SIGNIFICANT_SIGNAL_MASK
3930 #undef SIGNIFICANT_SIGNAL_MASK
3931 #endif
3932 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
3933 
3934 static const char* get_signal_handler_name(address handler,
3935                                            char* buf, int buflen) {
3936   int offset;
3937   bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
3938   if (found) {
3939     // skip directory names
3940     const char *p1, *p2;
3941     p1 = buf;
3942     size_t len = strlen(os::file_separator());
3943     while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
3944     jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
3945   } else {
3946     jio_snprintf(buf, buflen, PTR_FORMAT, handler);
3947   }
3948   return buf;
3949 }
3950 
3951 static void print_signal_handler(outputStream* st, int sig,
3952                                  char* buf, size_t buflen) {
3953   struct sigaction sa;
3954 
3955   sigaction(sig, NULL, &sa);
3956 
3957   // See comment for SIGNIFICANT_SIGNAL_MASK define
3958   sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
3959 
3960   st->print("%s: ", os::exception_name(sig, buf, buflen));
3961 
3962   address handler = (sa.sa_flags & SA_SIGINFO)
3963     ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
3964     : CAST_FROM_FN_PTR(address, sa.sa_handler);
3965 
3966   if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
3967     st->print("SIG_DFL");
3968   } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
3969     st->print("SIG_IGN");
3970   } else {
3971     st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
3972   }
3973 
3974   st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask);
3975 
3976   address rh = VMError::get_resetted_sighandler(sig);
3977   // May be, handler was resetted by VMError?
3978   if(rh != NULL) {
3979     handler = rh;
3980     sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
3981   }
3982 
3983   st->print(", sa_flags="   PTR32_FORMAT, sa.sa_flags);
3984 
3985   // Check: is it our handler?
3986   if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
3987      handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
3988     // It is our signal handler
3989     // check for flags, reset system-used one!
3990     if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
3991       st->print(
3992                 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
3993                 os::Linux::get_our_sigflags(sig));
3994     }
3995   }
3996   st->cr();
3997 }
3998 
3999 
4000 #define DO_SIGNAL_CHECK(sig) \
4001   if (!sigismember(&check_signal_done, sig)) \
4002     os::Linux::check_signal_handler(sig)
4003 
4004 // This method is a periodic task to check for misbehaving JNI applications
4005 // under CheckJNI, we can add any periodic checks here
4006 
4007 void os::run_periodic_checks() {
4008 
4009   if (check_signals == false) return;
4010 
4011   // SEGV and BUS if overridden could potentially prevent
4012   // generation of hs*.log in the event of a crash, debugging
4013   // such a case can be very challenging, so we absolutely
4014   // check the following for a good measure:
4015   DO_SIGNAL_CHECK(SIGSEGV);
4016   DO_SIGNAL_CHECK(SIGILL);
4017   DO_SIGNAL_CHECK(SIGFPE);
4018   DO_SIGNAL_CHECK(SIGBUS);
4019   DO_SIGNAL_CHECK(SIGPIPE);
4020   DO_SIGNAL_CHECK(SIGXFSZ);
4021 
4022 
4023   // ReduceSignalUsage allows the user to override these handlers
4024   // see comments at the very top and jvm_solaris.h
4025   if (!ReduceSignalUsage) {
4026     DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4027     DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4028     DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4029     DO_SIGNAL_CHECK(BREAK_SIGNAL);
4030   }
4031 
4032   DO_SIGNAL_CHECK(SR_signum);
4033   DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4034 }
4035 
4036 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4037 
4038 static os_sigaction_t os_sigaction = NULL;
4039 
4040 void os::Linux::check_signal_handler(int sig) {
4041   char buf[O_BUFLEN];
4042   address jvmHandler = NULL;
4043 
4044 
4045   struct sigaction act;
4046   if (os_sigaction == NULL) {
4047     // only trust the default sigaction, in case it has been interposed
4048     os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4049     if (os_sigaction == NULL) return;
4050   }
4051 
4052   os_sigaction(sig, (struct sigaction*)NULL, &act);
4053 
4054 
4055   act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4056 
4057   address thisHandler = (act.sa_flags & SA_SIGINFO)
4058     ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4059     : CAST_FROM_FN_PTR(address, act.sa_handler) ;
4060 
4061 
4062   switch(sig) {
4063   case SIGSEGV:
4064   case SIGBUS:
4065   case SIGFPE:
4066   case SIGPIPE:
4067   case SIGILL:
4068   case SIGXFSZ:
4069     jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4070     break;
4071 
4072   case SHUTDOWN1_SIGNAL:
4073   case SHUTDOWN2_SIGNAL:
4074   case SHUTDOWN3_SIGNAL:
4075   case BREAK_SIGNAL:
4076     jvmHandler = (address)user_handler();
4077     break;
4078 
4079   case INTERRUPT_SIGNAL:
4080     jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4081     break;
4082 
4083   default:
4084     if (sig == SR_signum) {
4085       jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4086     } else {
4087       return;
4088     }
4089     break;
4090   }
4091 
4092   if (thisHandler != jvmHandler) {
4093     tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4094     tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4095     tty->print_cr("  found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4096     // No need to check this sig any longer
4097     sigaddset(&check_signal_done, sig);
4098   } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4099     tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4100     tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4101     tty->print_cr("  found:" PTR32_FORMAT, act.sa_flags);
4102     // No need to check this sig any longer
4103     sigaddset(&check_signal_done, sig);
4104   }
4105 
4106   // Dump all the signal
4107   if (sigismember(&check_signal_done, sig)) {
4108     print_signal_handlers(tty, buf, O_BUFLEN);
4109   }
4110 }
4111 
4112 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
4113 
4114 extern bool signal_name(int signo, char* buf, size_t len);
4115 
4116 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4117   if (0 < exception_code && exception_code <= SIGRTMAX) {
4118     // signal
4119     if (!signal_name(exception_code, buf, size)) {
4120       jio_snprintf(buf, size, "SIG%d", exception_code);
4121     }
4122     return buf;
4123   } else {
4124     return NULL;
4125   }
4126 }
4127 
4128 // this is called _before_ the most of global arguments have been parsed
4129 void os::init(void) {
4130   char dummy;   /* used to get a guess on initial stack address */
4131 //  first_hrtime = gethrtime();
4132 
4133   // With LinuxThreads the JavaMain thread pid (primordial thread)
4134   // is different than the pid of the java launcher thread.
4135   // So, on Linux, the launcher thread pid is passed to the VM
4136   // via the sun.java.launcher.pid property.
4137   // Use this property instead of getpid() if it was correctly passed.
4138   // See bug 6351349.
4139   pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4140 
4141   _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4142 
4143   clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4144 
4145   init_random(1234567);
4146 
4147   ThreadCritical::initialize();
4148 
4149   Linux::set_page_size(sysconf(_SC_PAGESIZE));
4150   if (Linux::page_size() == -1) {
4151     fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4152                   strerror(errno)));
4153   }
4154   init_page_sizes((size_t) Linux::page_size());
4155 
4156   Linux::initialize_system_info();
4157 
4158   // main_thread points to the aboriginal thread
4159   Linux::_main_thread = pthread_self();
4160 
4161   Linux::clock_init();
4162   initial_time_count = os::elapsed_counter();
4163   pthread_mutex_init(&dl_mutex, NULL);
4164 }
4165 
4166 // To install functions for atexit system call
4167 extern "C" {
4168   static void perfMemory_exit_helper() {
4169     perfMemory_exit();
4170   }
4171 }
4172 
4173 // this is called _after_ the global arguments have been parsed
4174 jint os::init_2(void)
4175 {
4176   Linux::fast_thread_clock_init();
4177 
4178   // Allocate a single page and mark it as readable for safepoint polling
4179   address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4180   guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
4181 
4182   os::set_polling_page( polling_page );
4183 
4184 #ifndef PRODUCT
4185   if(Verbose && PrintMiscellaneous)
4186     tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
4187 #endif
4188 
4189   if (!UseMembar) {
4190     address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4191     guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page");
4192     os::set_memory_serialize_page( mem_serialize_page );
4193 
4194 #ifndef PRODUCT
4195     if(Verbose && PrintMiscellaneous)
4196       tty->print("[Memory Serialize  Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
4197 #endif
4198   }
4199 
4200   os::large_page_init();
4201 
4202   // initialize suspend/resume support - must do this before signal_sets_init()
4203   if (SR_initialize() != 0) {
4204     perror("SR_initialize failed");
4205     return JNI_ERR;
4206   }
4207 
4208   Linux::signal_sets_init();
4209   Linux::install_signal_handlers();
4210 
4211   // Check minimum allowable stack size for thread creation and to initialize
4212   // the java system classes, including StackOverflowError - depends on page
4213   // size.  Add a page for compiler2 recursion in main thread.
4214   // Add in 2*BytesPerWord times page size to account for VM stack during
4215   // class initialization depending on 32 or 64 bit VM.
4216   os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4217             (size_t)(StackYellowPages+StackRedPages+StackShadowPages+
4218                     2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::page_size());
4219 
4220   size_t threadStackSizeInBytes = ThreadStackSize * K;
4221   if (threadStackSizeInBytes != 0 &&
4222       threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4223         tty->print_cr("\nThe stack size specified is too small, "
4224                       "Specify at least %dk",
4225                       os::Linux::min_stack_allowed/ K);
4226         return JNI_ERR;
4227   }
4228 
4229   // Make the stack size a multiple of the page size so that
4230   // the yellow/red zones can be guarded.
4231   JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4232         vm_page_size()));
4233 
4234   Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4235 
4236   Linux::libpthread_init();
4237   if (PrintMiscellaneous && (Verbose || WizardMode)) {
4238      tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4239           Linux::glibc_version(), Linux::libpthread_version(),
4240           Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4241   }
4242 
4243   if (UseNUMA) {
4244     if (!Linux::libnuma_init()) {
4245       UseNUMA = false;
4246     } else {
4247       if ((Linux::numa_max_node() < 1)) {
4248         // There's only one node(they start from 0), disable NUMA.
4249         UseNUMA = false;
4250       }
4251     }
4252     // With SHM large pages we cannot uncommit a page, so there's not way
4253     // we can make the adaptive lgrp chunk resizing work. If the user specified
4254     // both UseNUMA and UseLargePages (or UseSHM) on the command line - warn and
4255     // disable adaptive resizing.
4256     if (UseNUMA && UseLargePages && UseSHM) {
4257       if (!FLAG_IS_DEFAULT(UseNUMA)) {
4258         if (FLAG_IS_DEFAULT(UseLargePages) && FLAG_IS_DEFAULT(UseSHM)) {
4259           UseLargePages = false;
4260         } else {
4261           warning("UseNUMA is not fully compatible with SHM large pages, disabling adaptive resizing");
4262           UseAdaptiveSizePolicy = false;
4263           UseAdaptiveNUMAChunkSizing = false;
4264         }
4265       } else {
4266         UseNUMA = false;
4267       }
4268     }
4269     if (!UseNUMA && ForceNUMA) {
4270       UseNUMA = true;
4271     }
4272   }
4273 
4274   if (MaxFDLimit) {
4275     // set the number of file descriptors to max. print out error
4276     // if getrlimit/setrlimit fails but continue regardless.
4277     struct rlimit nbr_files;
4278     int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4279     if (status != 0) {
4280       if (PrintMiscellaneous && (Verbose || WizardMode))
4281         perror("os::init_2 getrlimit failed");
4282     } else {
4283       nbr_files.rlim_cur = nbr_files.rlim_max;
4284       status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4285       if (status != 0) {
4286         if (PrintMiscellaneous && (Verbose || WizardMode))
4287           perror("os::init_2 setrlimit failed");
4288       }
4289     }
4290   }
4291 
4292   // Initialize lock used to serialize thread creation (see os::create_thread)
4293   Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4294 
4295   // at-exit methods are called in the reverse order of their registration.
4296   // atexit functions are called on return from main or as a result of a
4297   // call to exit(3C). There can be only 32 of these functions registered
4298   // and atexit() does not set errno.
4299 
4300   if (PerfAllowAtExitRegistration) {
4301     // only register atexit functions if PerfAllowAtExitRegistration is set.
4302     // atexit functions can be delayed until process exit time, which
4303     // can be problematic for embedded VM situations. Embedded VMs should
4304     // call DestroyJavaVM() to assure that VM resources are released.
4305 
4306     // note: perfMemory_exit_helper atexit function may be removed in
4307     // the future if the appropriate cleanup code can be added to the
4308     // VM_Exit VMOperation's doit method.
4309     if (atexit(perfMemory_exit_helper) != 0) {
4310       warning("os::init2 atexit(perfMemory_exit_helper) failed");
4311     }
4312   }
4313 
4314   // initialize thread priority policy
4315   prio_init();
4316 
4317   return JNI_OK;
4318 }
4319 
4320 // this is called at the end of vm_initialization
4321 void os::init_3(void)
4322 {
4323 #ifdef JAVASE_EMBEDDED
4324   // Start the MemNotifyThread
4325   if (LowMemoryProtection) {
4326     MemNotifyThread::start();
4327   }
4328   return;
4329 #endif
4330 }
4331 
4332 // Mark the polling page as unreadable
4333 void os::make_polling_page_unreadable(void) {
4334   if( !guard_memory((char*)_polling_page, Linux::page_size()) )
4335     fatal("Could not disable polling page");
4336 };
4337 
4338 // Mark the polling page as readable
4339 void os::make_polling_page_readable(void) {
4340   if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4341     fatal("Could not enable polling page");
4342   }
4343 };
4344 
4345 int os::active_processor_count() {
4346   // Linux doesn't yet have a (official) notion of processor sets,
4347   // so just return the number of online processors.
4348   int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4349   assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4350   return online_cpus;
4351 }
4352 
4353 bool os::distribute_processes(uint length, uint* distribution) {
4354   // Not yet implemented.
4355   return false;
4356 }
4357 
4358 bool os::bind_to_processor(uint processor_id) {
4359   // Not yet implemented.
4360   return false;
4361 }
4362 
4363 ///
4364 
4365 // Suspends the target using the signal mechanism and then grabs the PC before
4366 // resuming the target. Used by the flat-profiler only
4367 ExtendedPC os::get_thread_pc(Thread* thread) {
4368   // Make sure that it is called by the watcher for the VMThread
4369   assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4370   assert(thread->is_VM_thread(), "Can only be called for VMThread");
4371 
4372   ExtendedPC epc;
4373 
4374   OSThread* osthread = thread->osthread();
4375   if (do_suspend(osthread)) {
4376     if (osthread->ucontext() != NULL) {
4377       epc = os::Linux::ucontext_get_pc(osthread->ucontext());
4378     } else {
4379       // NULL context is unexpected, double-check this is the VMThread
4380       guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4381     }
4382     do_resume(osthread);
4383   }
4384   // failure means pthread_kill failed for some reason - arguably this is
4385   // a fatal problem, but such problems are ignored elsewhere
4386 
4387   return epc;
4388 }
4389 
4390 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
4391 {
4392    if (is_NPTL()) {
4393       return pthread_cond_timedwait(_cond, _mutex, _abstime);
4394    } else {
4395 #ifndef IA64
4396       // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4397       // word back to default 64bit precision if condvar is signaled. Java
4398       // wants 53bit precision.  Save and restore current value.
4399       int fpu = get_fpu_control_word();
4400 #endif // IA64
4401       int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4402 #ifndef IA64
4403       set_fpu_control_word(fpu);
4404 #endif // IA64
4405       return status;
4406    }
4407 }
4408 
4409 ////////////////////////////////////////////////////////////////////////////////
4410 // debug support
4411 
4412 static address same_page(address x, address y) {
4413   int page_bits = -os::vm_page_size();
4414   if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits))
4415     return x;
4416   else if (x > y)
4417     return (address)(intptr_t(y) | ~page_bits) + 1;
4418   else
4419     return (address)(intptr_t(y) & page_bits);
4420 }
4421 
4422 bool os::find(address addr, outputStream* st) {
4423   Dl_info dlinfo;
4424   memset(&dlinfo, 0, sizeof(dlinfo));
4425   if (dladdr(addr, &dlinfo)) {
4426     st->print(PTR_FORMAT ": ", addr);
4427     if (dlinfo.dli_sname != NULL) {
4428       st->print("%s+%#x", dlinfo.dli_sname,
4429                  addr - (intptr_t)dlinfo.dli_saddr);
4430     } else if (dlinfo.dli_fname) {
4431       st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4432     } else {
4433       st->print("<absolute address>");
4434     }
4435     if (dlinfo.dli_fname) {
4436       st->print(" in %s", dlinfo.dli_fname);
4437     }
4438     if (dlinfo.dli_fbase) {
4439       st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4440     }
4441     st->cr();
4442 
4443     if (Verbose) {
4444       // decode some bytes around the PC
4445       address begin = same_page(addr-40, addr);
4446       address end   = same_page(addr+40, addr);
4447       address       lowest = (address) dlinfo.dli_sname;
4448       if (!lowest)  lowest = (address) dlinfo.dli_fbase;
4449       if (begin < lowest)  begin = lowest;
4450       Dl_info dlinfo2;
4451       if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr
4452           && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
4453         end = (address) dlinfo2.dli_saddr;
4454       Disassembler::decode(begin, end, st);
4455     }
4456     return true;
4457   }
4458   return false;
4459 }
4460 
4461 ////////////////////////////////////////////////////////////////////////////////
4462 // misc
4463 
4464 // This does not do anything on Linux. This is basically a hook for being
4465 // able to use structured exception handling (thread-local exception filters)
4466 // on, e.g., Win32.
4467 void
4468 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
4469                          JavaCallArguments* args, Thread* thread) {
4470   f(value, method, args, thread);
4471 }
4472 
4473 void os::print_statistics() {
4474 }
4475 
4476 int os::message_box(const char* title, const char* message) {
4477   int i;
4478   fdStream err(defaultStream::error_fd());
4479   for (i = 0; i < 78; i++) err.print_raw("=");
4480   err.cr();
4481   err.print_raw_cr(title);
4482   for (i = 0; i < 78; i++) err.print_raw("-");
4483   err.cr();
4484   err.print_raw_cr(message);
4485   for (i = 0; i < 78; i++) err.print_raw("=");
4486   err.cr();
4487 
4488   char buf[16];
4489   // Prevent process from exiting upon "read error" without consuming all CPU
4490   while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
4491 
4492   return buf[0] == 'y' || buf[0] == 'Y';
4493 }
4494 
4495 int os::stat(const char *path, struct stat *sbuf) {
4496   char pathbuf[MAX_PATH];
4497   if (strlen(path) > MAX_PATH - 1) {
4498     errno = ENAMETOOLONG;
4499     return -1;
4500   }
4501   os::native_path(strcpy(pathbuf, path));
4502   return ::stat(pathbuf, sbuf);
4503 }
4504 
4505 bool os::check_heap(bool force) {
4506   return true;
4507 }
4508 
4509 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
4510   return ::vsnprintf(buf, count, format, args);
4511 }
4512 
4513 // Is a (classpath) directory empty?
4514 bool os::dir_is_empty(const char* path) {
4515   DIR *dir = NULL;
4516   struct dirent *ptr;
4517 
4518   dir = opendir(path);
4519   if (dir == NULL) return true;
4520 
4521   /* Scan the directory */
4522   bool result = true;
4523   char buf[sizeof(struct dirent) + MAX_PATH];
4524   while (result && (ptr = ::readdir(dir)) != NULL) {
4525     if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
4526       result = false;
4527     }
4528   }
4529   closedir(dir);
4530   return result;
4531 }
4532 
4533 // This code originates from JDK's sysOpen and open64_w
4534 // from src/solaris/hpi/src/system_md.c
4535 
4536 #ifndef O_DELETE
4537 #define O_DELETE 0x10000
4538 #endif
4539 
4540 // Open a file. Unlink the file immediately after open returns
4541 // if the specified oflag has the O_DELETE flag set.
4542 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
4543 
4544 int os::open(const char *path, int oflag, int mode) {
4545 
4546   if (strlen(path) > MAX_PATH - 1) {
4547     errno = ENAMETOOLONG;
4548     return -1;
4549   }
4550   int fd;
4551   int o_delete = (oflag & O_DELETE);
4552   oflag = oflag & ~O_DELETE;
4553 
4554   fd = ::open64(path, oflag, mode);
4555   if (fd == -1) return -1;
4556 
4557   //If the open succeeded, the file might still be a directory
4558   {
4559     struct stat64 buf64;
4560     int ret = ::fstat64(fd, &buf64);
4561     int st_mode = buf64.st_mode;
4562 
4563     if (ret != -1) {
4564       if ((st_mode & S_IFMT) == S_IFDIR) {
4565         errno = EISDIR;
4566         ::close(fd);
4567         return -1;
4568       }
4569     } else {
4570       ::close(fd);
4571       return -1;
4572     }
4573   }
4574 
4575     /*
4576      * All file descriptors that are opened in the JVM and not
4577      * specifically destined for a subprocess should have the
4578      * close-on-exec flag set.  If we don't set it, then careless 3rd
4579      * party native code might fork and exec without closing all
4580      * appropriate file descriptors (e.g. as we do in closeDescriptors in
4581      * UNIXProcess.c), and this in turn might:
4582      *
4583      * - cause end-of-file to fail to be detected on some file
4584      *   descriptors, resulting in mysterious hangs, or
4585      *
4586      * - might cause an fopen in the subprocess to fail on a system
4587      *   suffering from bug 1085341.
4588      *
4589      * (Yes, the default setting of the close-on-exec flag is a Unix
4590      * design flaw)
4591      *
4592      * See:
4593      * 1085341: 32-bit stdio routines should support file descriptors >255
4594      * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
4595      * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
4596      */
4597 #ifdef FD_CLOEXEC
4598     {
4599         int flags = ::fcntl(fd, F_GETFD);
4600         if (flags != -1)
4601             ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
4602     }
4603 #endif
4604 
4605   if (o_delete != 0) {
4606     ::unlink(path);
4607   }
4608   return fd;
4609 }
4610 
4611 
4612 // create binary file, rewriting existing file if required
4613 int os::create_binary_file(const char* path, bool rewrite_existing) {
4614   int oflags = O_WRONLY | O_CREAT;
4615   if (!rewrite_existing) {
4616     oflags |= O_EXCL;
4617   }
4618   return ::open64(path, oflags, S_IREAD | S_IWRITE);
4619 }
4620 
4621 // return current position of file pointer
4622 jlong os::current_file_offset(int fd) {
4623   return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
4624 }
4625 
4626 // move file pointer to the specified offset
4627 jlong os::seek_to_file_offset(int fd, jlong offset) {
4628   return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
4629 }
4630 
4631 // This code originates from JDK's sysAvailable
4632 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
4633 
4634 int os::available(int fd, jlong *bytes) {
4635   jlong cur, end;
4636   int mode;
4637   struct stat64 buf64;
4638 
4639   if (::fstat64(fd, &buf64) >= 0) {
4640     mode = buf64.st_mode;
4641     if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
4642       /*
4643       * XXX: is the following call interruptible? If so, this might
4644       * need to go through the INTERRUPT_IO() wrapper as for other
4645       * blocking, interruptible calls in this file.
4646       */
4647       int n;
4648       if (::ioctl(fd, FIONREAD, &n) >= 0) {
4649         *bytes = n;
4650         return 1;
4651       }
4652     }
4653   }
4654   if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
4655     return 0;
4656   } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
4657     return 0;
4658   } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
4659     return 0;
4660   }
4661   *bytes = end - cur;
4662   return 1;
4663 }
4664 
4665 int os::socket_available(int fd, jint *pbytes) {
4666   // Linux doc says EINTR not returned, unlike Solaris
4667   int ret = ::ioctl(fd, FIONREAD, pbytes);
4668 
4669   //%% note ioctl can return 0 when successful, JVM_SocketAvailable
4670   // is expected to return 0 on failure and 1 on success to the jdk.
4671   return (ret < 0) ? 0 : 1;
4672 }
4673 
4674 // Map a block of memory.
4675 char* os::map_memory(int fd, const char* file_name, size_t file_offset,
4676                      char *addr, size_t bytes, bool read_only,
4677                      bool allow_exec) {
4678   int prot;
4679   int flags;
4680 
4681   if (read_only) {
4682     prot = PROT_READ;
4683     flags = MAP_SHARED;
4684   } else {
4685     prot = PROT_READ | PROT_WRITE;
4686     flags = MAP_PRIVATE;
4687   }
4688 
4689   if (allow_exec) {
4690     prot |= PROT_EXEC;
4691   }
4692 
4693   if (addr != NULL) {
4694     flags |= MAP_FIXED;
4695   }
4696 
4697   char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
4698                                      fd, file_offset);
4699   if (mapped_address == MAP_FAILED) {
4700     return NULL;
4701   }
4702   return mapped_address;
4703 }
4704 
4705 
4706 // Remap a block of memory.
4707 char* os::remap_memory(int fd, const char* file_name, size_t file_offset,
4708                        char *addr, size_t bytes, bool read_only,
4709                        bool allow_exec) {
4710   // same as map_memory() on this OS
4711   return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
4712                         allow_exec);
4713 }
4714 
4715 
4716 // Unmap a block of memory.
4717 bool os::unmap_memory(char* addr, size_t bytes) {
4718   return munmap(addr, bytes) == 0;
4719 }
4720 
4721 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
4722 
4723 static clockid_t thread_cpu_clockid(Thread* thread) {
4724   pthread_t tid = thread->osthread()->pthread_id();
4725   clockid_t clockid;
4726 
4727   // Get thread clockid
4728   int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
4729   assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
4730   return clockid;
4731 }
4732 
4733 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
4734 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
4735 // of a thread.
4736 //
4737 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
4738 // the fast estimate available on the platform.
4739 
4740 jlong os::current_thread_cpu_time() {
4741   if (os::Linux::supports_fast_thread_cpu_time()) {
4742     return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4743   } else {
4744     // return user + sys since the cost is the same
4745     return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
4746   }
4747 }
4748 
4749 jlong os::thread_cpu_time(Thread* thread) {
4750   // consistent with what current_thread_cpu_time() returns
4751   if (os::Linux::supports_fast_thread_cpu_time()) {
4752     return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4753   } else {
4754     return slow_thread_cpu_time(thread, true /* user + sys */);
4755   }
4756 }
4757 
4758 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
4759   if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4760     return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4761   } else {
4762     return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
4763   }
4764 }
4765 
4766 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4767   if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4768     return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4769   } else {
4770     return slow_thread_cpu_time(thread, user_sys_cpu_time);
4771   }
4772 }
4773 
4774 //
4775 //  -1 on error.
4776 //
4777 
4778 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4779   static bool proc_pid_cpu_avail = true;
4780   static bool proc_task_unchecked = true;
4781   static const char *proc_stat_path = "/proc/%d/stat";
4782   pid_t  tid = thread->osthread()->thread_id();
4783   int i;
4784   char *s;
4785   char stat[2048];
4786   int statlen;
4787   char proc_name[64];
4788   int count;
4789   long sys_time, user_time;
4790   char string[64];
4791   char cdummy;
4792   int idummy;
4793   long ldummy;
4794   FILE *fp;
4795 
4796   // We first try accessing /proc/<pid>/cpu since this is faster to
4797   // process.  If this file is not present (linux kernels 2.5 and above)
4798   // then we open /proc/<pid>/stat.
4799   if ( proc_pid_cpu_avail ) {
4800     sprintf(proc_name, "/proc/%d/cpu", tid);
4801     fp =  fopen(proc_name, "r");
4802     if ( fp != NULL ) {
4803       count = fscanf( fp, "%s %lu %lu\n", string, &user_time, &sys_time);
4804       fclose(fp);
4805       if ( count != 3 ) return -1;
4806 
4807       if (user_sys_cpu_time) {
4808         return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
4809       } else {
4810         return (jlong)user_time * (1000000000 / clock_tics_per_sec);
4811       }
4812     }
4813     else proc_pid_cpu_avail = false;
4814   }
4815 
4816   // The /proc/<tid>/stat aggregates per-process usage on
4817   // new Linux kernels 2.6+ where NPTL is supported.
4818   // The /proc/self/task/<tid>/stat still has the per-thread usage.
4819   // See bug 6328462.
4820   // There can be no directory /proc/self/task on kernels 2.4 with NPTL
4821   // and possibly in some other cases, so we check its availability.
4822   if (proc_task_unchecked && os::Linux::is_NPTL()) {
4823     // This is executed only once
4824     proc_task_unchecked = false;
4825     fp = fopen("/proc/self/task", "r");
4826     if (fp != NULL) {
4827       proc_stat_path = "/proc/self/task/%d/stat";
4828       fclose(fp);
4829     }
4830   }
4831 
4832   sprintf(proc_name, proc_stat_path, tid);
4833   fp = fopen(proc_name, "r");
4834   if ( fp == NULL ) return -1;
4835   statlen = fread(stat, 1, 2047, fp);
4836   stat[statlen] = '\0';
4837   fclose(fp);
4838 
4839   // Skip pid and the command string. Note that we could be dealing with
4840   // weird command names, e.g. user could decide to rename java launcher
4841   // to "java 1.4.2 :)", then the stat file would look like
4842   //                1234 (java 1.4.2 :)) R ... ...
4843   // We don't really need to know the command string, just find the last
4844   // occurrence of ")" and then start parsing from there. See bug 4726580.
4845   s = strrchr(stat, ')');
4846   i = 0;
4847   if (s == NULL ) return -1;
4848 
4849   // Skip blank chars
4850   do s++; while (isspace(*s));
4851 
4852   count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
4853                  &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
4854                  &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
4855                  &user_time, &sys_time);
4856   if ( count != 13 ) return -1;
4857   if (user_sys_cpu_time) {
4858     return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
4859   } else {
4860     return (jlong)user_time * (1000000000 / clock_tics_per_sec);
4861   }
4862 }
4863 
4864 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4865   info_ptr->max_value = ALL_64_BITS;       // will not wrap in less than 64 bits
4866   info_ptr->may_skip_backward = false;     // elapsed time not wall time
4867   info_ptr->may_skip_forward = false;      // elapsed time not wall time
4868   info_ptr->kind = JVMTI_TIMER_TOTAL_CPU;  // user+system time is returned
4869 }
4870 
4871 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4872   info_ptr->max_value = ALL_64_BITS;       // will not wrap in less than 64 bits
4873   info_ptr->may_skip_backward = false;     // elapsed time not wall time
4874   info_ptr->may_skip_forward = false;      // elapsed time not wall time
4875   info_ptr->kind = JVMTI_TIMER_TOTAL_CPU;  // user+system time is returned
4876 }
4877 
4878 bool os::is_thread_cpu_time_supported() {
4879   return true;
4880 }
4881 
4882 // System loadavg support.  Returns -1 if load average cannot be obtained.
4883 // Linux doesn't yet have a (official) notion of processor sets,
4884 // so just return the system wide load average.
4885 int os::loadavg(double loadavg[], int nelem) {
4886   return ::getloadavg(loadavg, nelem);
4887 }
4888 
4889 void os::pause() {
4890   char filename[MAX_PATH];
4891   if (PauseAtStartupFile && PauseAtStartupFile[0]) {
4892     jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
4893   } else {
4894     jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
4895   }
4896 
4897   int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
4898   if (fd != -1) {
4899     struct stat buf;
4900     ::close(fd);
4901     while (::stat(filename, &buf) == 0) {
4902       (void)::poll(NULL, 0, 100);
4903     }
4904   } else {
4905     jio_fprintf(stderr,
4906       "Could not open pause file '%s', continuing immediately.\n", filename);
4907   }
4908 }
4909 
4910 
4911 // Refer to the comments in os_solaris.cpp park-unpark.
4912 //
4913 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
4914 // hang indefinitely.  For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
4915 // For specifics regarding the bug see GLIBC BUGID 261237 :
4916 //    http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
4917 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
4918 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
4919 // is used.  (The simple C test-case provided in the GLIBC bug report manifests the
4920 // hang).  The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
4921 // and monitorenter when we're using 1-0 locking.  All those operations may result in
4922 // calls to pthread_cond_timedwait().  Using LD_ASSUME_KERNEL to use an older version
4923 // of libpthread avoids the problem, but isn't practical.
4924 //
4925 // Possible remedies:
4926 //
4927 // 1.   Establish a minimum relative wait time.  50 to 100 msecs seems to work.
4928 //      This is palliative and probabilistic, however.  If the thread is preempted
4929 //      between the call to compute_abstime() and pthread_cond_timedwait(), more
4930 //      than the minimum period may have passed, and the abstime may be stale (in the
4931 //      past) resultin in a hang.   Using this technique reduces the odds of a hang
4932 //      but the JVM is still vulnerable, particularly on heavily loaded systems.
4933 //
4934 // 2.   Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
4935 //      of the usual flag-condvar-mutex idiom.  The write side of the pipe is set
4936 //      NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
4937 //      reduces to poll()+read().  This works well, but consumes 2 FDs per extant
4938 //      thread.
4939 //
4940 // 3.   Embargo pthread_cond_timedwait() and implement a native "chron" thread
4941 //      that manages timeouts.  We'd emulate pthread_cond_timedwait() by enqueuing
4942 //      a timeout request to the chron thread and then blocking via pthread_cond_wait().
4943 //      This also works well.  In fact it avoids kernel-level scalability impediments
4944 //      on certain platforms that don't handle lots of active pthread_cond_timedwait()
4945 //      timers in a graceful fashion.
4946 //
4947 // 4.   When the abstime value is in the past it appears that control returns
4948 //      correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
4949 //      Subsequent timedwait/wait calls may hang indefinitely.  Given that, we
4950 //      can avoid the problem by reinitializing the condvar -- by cond_destroy()
4951 //      followed by cond_init() -- after all calls to pthread_cond_timedwait().
4952 //      It may be possible to avoid reinitialization by checking the return
4953 //      value from pthread_cond_timedwait().  In addition to reinitializing the
4954 //      condvar we must establish the invariant that cond_signal() is only called
4955 //      within critical sections protected by the adjunct mutex.  This prevents
4956 //      cond_signal() from "seeing" a condvar that's in the midst of being
4957 //      reinitialized or that is corrupt.  Sadly, this invariant obviates the
4958 //      desirable signal-after-unlock optimization that avoids futile context switching.
4959 //
4960 //      I'm also concerned that some versions of NTPL might allocate an auxilliary
4961 //      structure when a condvar is used or initialized.  cond_destroy()  would
4962 //      release the helper structure.  Our reinitialize-after-timedwait fix
4963 //      put excessive stress on malloc/free and locks protecting the c-heap.
4964 //
4965 // We currently use (4).  See the WorkAroundNTPLTimedWaitHang flag.
4966 // It may be possible to refine (4) by checking the kernel and NTPL verisons
4967 // and only enabling the work-around for vulnerable environments.
4968 
4969 // utility to compute the abstime argument to timedwait:
4970 // millis is the relative timeout time
4971 // abstime will be the absolute timeout time
4972 // TODO: replace compute_abstime() with unpackTime()
4973 
4974 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
4975   if (millis < 0)  millis = 0;
4976   struct timeval now;
4977   int status = gettimeofday(&now, NULL);
4978   assert(status == 0, "gettimeofday");
4979   jlong seconds = millis / 1000;
4980   millis %= 1000;
4981   if (seconds > 50000000) { // see man cond_timedwait(3T)
4982     seconds = 50000000;
4983   }
4984   abstime->tv_sec = now.tv_sec  + seconds;
4985   long       usec = now.tv_usec + millis * 1000;
4986   if (usec >= 1000000) {
4987     abstime->tv_sec += 1;
4988     usec -= 1000000;
4989   }
4990   abstime->tv_nsec = usec * 1000;
4991   return abstime;
4992 }
4993 
4994 
4995 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
4996 // Conceptually TryPark() should be equivalent to park(0).
4997 
4998 int os::PlatformEvent::TryPark() {
4999   for (;;) {
5000     const int v = _Event ;
5001     guarantee ((v == 0) || (v == 1), "invariant") ;
5002     if (Atomic::cmpxchg (0, &_Event, v) == v) return v  ;
5003   }
5004 }
5005 
5006 void os::PlatformEvent::park() {       // AKA "down()"
5007   // Invariant: Only the thread associated with the Event/PlatformEvent
5008   // may call park().
5009   // TODO: assert that _Assoc != NULL or _Assoc == Self
5010   int v ;
5011   for (;;) {
5012       v = _Event ;
5013       if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5014   }
5015   guarantee (v >= 0, "invariant") ;
5016   if (v == 0) {
5017      // Do this the hard way by blocking ...
5018      int status = pthread_mutex_lock(_mutex);
5019      assert_status(status == 0, status, "mutex_lock");
5020      guarantee (_nParked == 0, "invariant") ;
5021      ++ _nParked ;
5022      while (_Event < 0) {
5023         status = pthread_cond_wait(_cond, _mutex);
5024         // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5025         // Treat this the same as if the wait was interrupted
5026         if (status == ETIME) { status = EINTR; }
5027         assert_status(status == 0 || status == EINTR, status, "cond_wait");
5028      }
5029      -- _nParked ;
5030 
5031     // In theory we could move the ST of 0 into _Event past the unlock(),
5032     // but then we'd need a MEMBAR after the ST.
5033     _Event = 0 ;
5034      status = pthread_mutex_unlock(_mutex);
5035      assert_status(status == 0, status, "mutex_unlock");
5036   }
5037   guarantee (_Event >= 0, "invariant") ;
5038 }
5039 
5040 int os::PlatformEvent::park(jlong millis) {
5041   guarantee (_nParked == 0, "invariant") ;
5042 
5043   int v ;
5044   for (;;) {
5045       v = _Event ;
5046       if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5047   }
5048   guarantee (v >= 0, "invariant") ;
5049   if (v != 0) return OS_OK ;
5050 
5051   // We do this the hard way, by blocking the thread.
5052   // Consider enforcing a minimum timeout value.
5053   struct timespec abst;
5054   compute_abstime(&abst, millis);
5055 
5056   int ret = OS_TIMEOUT;
5057   int status = pthread_mutex_lock(_mutex);
5058   assert_status(status == 0, status, "mutex_lock");
5059   guarantee (_nParked == 0, "invariant") ;
5060   ++_nParked ;
5061 
5062   // Object.wait(timo) will return because of
5063   // (a) notification
5064   // (b) timeout
5065   // (c) thread.interrupt
5066   //
5067   // Thread.interrupt and object.notify{All} both call Event::set.
5068   // That is, we treat thread.interrupt as a special case of notification.
5069   // The underlying Solaris implementation, cond_timedwait, admits
5070   // spurious/premature wakeups, but the JLS/JVM spec prevents the
5071   // JVM from making those visible to Java code.  As such, we must
5072   // filter out spurious wakeups.  We assume all ETIME returns are valid.
5073   //
5074   // TODO: properly differentiate simultaneous notify+interrupt.
5075   // In that case, we should propagate the notify to another waiter.
5076 
5077   while (_Event < 0) {
5078     status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5079     if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5080       pthread_cond_destroy (_cond);
5081       pthread_cond_init (_cond, NULL) ;
5082     }
5083     assert_status(status == 0 || status == EINTR ||
5084                   status == ETIME || status == ETIMEDOUT,
5085                   status, "cond_timedwait");
5086     if (!FilterSpuriousWakeups) break ;                 // previous semantics
5087     if (status == ETIME || status == ETIMEDOUT) break ;
5088     // We consume and ignore EINTR and spurious wakeups.
5089   }
5090   --_nParked ;
5091   if (_Event >= 0) {
5092      ret = OS_OK;
5093   }
5094   _Event = 0 ;
5095   status = pthread_mutex_unlock(_mutex);
5096   assert_status(status == 0, status, "mutex_unlock");
5097   assert (_nParked == 0, "invariant") ;
5098   return ret;
5099 }
5100 
5101 void os::PlatformEvent::unpark() {
5102   int v, AnyWaiters ;
5103   for (;;) {
5104       v = _Event ;
5105       if (v > 0) {
5106          // The LD of _Event could have reordered or be satisfied
5107          // by a read-aside from this processor's write buffer.
5108          // To avoid problems execute a barrier and then
5109          // ratify the value.
5110          OrderAccess::fence() ;
5111          if (_Event == v) return ;
5112          continue ;
5113       }
5114       if (Atomic::cmpxchg (v+1, &_Event, v) == v) break ;
5115   }
5116   if (v < 0) {
5117      // Wait for the thread associated with the event to vacate
5118      int status = pthread_mutex_lock(_mutex);
5119      assert_status(status == 0, status, "mutex_lock");
5120      AnyWaiters = _nParked ;
5121      assert (AnyWaiters == 0 || AnyWaiters == 1, "invariant") ;
5122      if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5123         AnyWaiters = 0 ;
5124         pthread_cond_signal (_cond);
5125      }
5126      status = pthread_mutex_unlock(_mutex);
5127      assert_status(status == 0, status, "mutex_unlock");
5128      if (AnyWaiters != 0) {
5129         status = pthread_cond_signal(_cond);
5130         assert_status(status == 0, status, "cond_signal");
5131      }
5132   }
5133 
5134   // Note that we signal() _after dropping the lock for "immortal" Events.
5135   // This is safe and avoids a common class of  futile wakeups.  In rare
5136   // circumstances this can cause a thread to return prematurely from
5137   // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5138   // simply re-test the condition and re-park itself.
5139 }
5140 
5141 
5142 // JSR166
5143 // -------------------------------------------------------
5144 
5145 /*
5146  * The solaris and linux implementations of park/unpark are fairly
5147  * conservative for now, but can be improved. They currently use a
5148  * mutex/condvar pair, plus a a count.
5149  * Park decrements count if > 0, else does a condvar wait.  Unpark
5150  * sets count to 1 and signals condvar.  Only one thread ever waits
5151  * on the condvar. Contention seen when trying to park implies that someone
5152  * is unparking you, so don't wait. And spurious returns are fine, so there
5153  * is no need to track notifications.
5154  */
5155 
5156 
5157 #define NANOSECS_PER_SEC 1000000000
5158 #define NANOSECS_PER_MILLISEC 1000000
5159 #define MAX_SECS 100000000
5160 /*
5161  * This code is common to linux and solaris and will be moved to a
5162  * common place in dolphin.
5163  *
5164  * The passed in time value is either a relative time in nanoseconds
5165  * or an absolute time in milliseconds. Either way it has to be unpacked
5166  * into suitable seconds and nanoseconds components and stored in the
5167  * given timespec structure.
5168  * Given time is a 64-bit value and the time_t used in the timespec is only
5169  * a signed-32-bit value (except on 64-bit Linux) we have to watch for
5170  * overflow if times way in the future are given. Further on Solaris versions
5171  * prior to 10 there is a restriction (see cond_timedwait) that the specified
5172  * number of seconds, in abstime, is less than current_time  + 100,000,000.
5173  * As it will be 28 years before "now + 100000000" will overflow we can
5174  * ignore overflow and just impose a hard-limit on seconds using the value
5175  * of "now + 100,000,000". This places a limit on the timeout of about 3.17
5176  * years from "now".
5177  */
5178 
5179 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5180   assert (time > 0, "convertTime");
5181 
5182   struct timeval now;
5183   int status = gettimeofday(&now, NULL);
5184   assert(status == 0, "gettimeofday");
5185 
5186   time_t max_secs = now.tv_sec + MAX_SECS;
5187 
5188   if (isAbsolute) {
5189     jlong secs = time / 1000;
5190     if (secs > max_secs) {
5191       absTime->tv_sec = max_secs;
5192     }
5193     else {
5194       absTime->tv_sec = secs;
5195     }
5196     absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5197   }
5198   else {
5199     jlong secs = time / NANOSECS_PER_SEC;
5200     if (secs >= MAX_SECS) {
5201       absTime->tv_sec = max_secs;
5202       absTime->tv_nsec = 0;
5203     }
5204     else {
5205       absTime->tv_sec = now.tv_sec + secs;
5206       absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5207       if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5208         absTime->tv_nsec -= NANOSECS_PER_SEC;
5209         ++absTime->tv_sec; // note: this must be <= max_secs
5210       }
5211     }
5212   }
5213   assert(absTime->tv_sec >= 0, "tv_sec < 0");
5214   assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5215   assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5216   assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5217 }
5218 
5219 void Parker::park(bool isAbsolute, jlong time) {
5220   // Optional fast-path check:
5221   // Return immediately if a permit is available.
5222   if (_counter > 0) {
5223       _counter = 0 ;
5224       OrderAccess::fence();
5225       return ;
5226   }
5227 
5228   Thread* thread = Thread::current();
5229   assert(thread->is_Java_thread(), "Must be JavaThread");
5230   JavaThread *jt = (JavaThread *)thread;
5231 
5232   // Optional optimization -- avoid state transitions if there's an interrupt pending.
5233   // Check interrupt before trying to wait
5234   if (Thread::is_interrupted(thread, false)) {
5235     return;
5236   }
5237 
5238   // Next, demultiplex/decode time arguments
5239   timespec absTime;
5240   if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
5241     return;
5242   }
5243   if (time > 0) {
5244     unpackTime(&absTime, isAbsolute, time);
5245   }
5246 
5247 
5248   // Enter safepoint region
5249   // Beware of deadlocks such as 6317397.
5250   // The per-thread Parker:: mutex is a classic leaf-lock.
5251   // In particular a thread must never block on the Threads_lock while
5252   // holding the Parker:: mutex.  If safepoints are pending both the
5253   // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5254   ThreadBlockInVM tbivm(jt);
5255 
5256   // Don't wait if cannot get lock since interference arises from
5257   // unblocking.  Also. check interrupt before trying wait
5258   if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5259     return;
5260   }
5261 
5262   int status ;
5263   if (_counter > 0)  { // no wait needed
5264     _counter = 0;
5265     status = pthread_mutex_unlock(_mutex);
5266     assert (status == 0, "invariant") ;
5267     OrderAccess::fence();
5268     return;
5269   }
5270 
5271 #ifdef ASSERT
5272   // Don't catch signals while blocked; let the running threads have the signals.
5273   // (This allows a debugger to break into the running thread.)
5274   sigset_t oldsigs;
5275   sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5276   pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5277 #endif
5278 
5279   OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5280   jt->set_suspend_equivalent();
5281   // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5282 
5283   if (time == 0) {
5284     status = pthread_cond_wait (_cond, _mutex) ;
5285   } else {
5286     status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ;
5287     if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5288       pthread_cond_destroy (_cond) ;
5289       pthread_cond_init    (_cond, NULL);
5290     }
5291   }
5292   assert_status(status == 0 || status == EINTR ||
5293                 status == ETIME || status == ETIMEDOUT,
5294                 status, "cond_timedwait");
5295 
5296 #ifdef ASSERT
5297   pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5298 #endif
5299 
5300   _counter = 0 ;
5301   status = pthread_mutex_unlock(_mutex) ;
5302   assert_status(status == 0, status, "invariant") ;
5303   // If externally suspended while waiting, re-suspend
5304   if (jt->handle_special_suspend_equivalent_condition()) {
5305     jt->java_suspend_self();
5306   }
5307 
5308   OrderAccess::fence();
5309 }
5310 
5311 void Parker::unpark() {
5312   int s, status ;
5313   status = pthread_mutex_lock(_mutex);
5314   assert (status == 0, "invariant") ;
5315   s = _counter;
5316   _counter = 1;
5317   if (s < 1) {
5318      if (WorkAroundNPTLTimedWaitHang) {
5319         status = pthread_cond_signal (_cond) ;
5320         assert (status == 0, "invariant") ;
5321         status = pthread_mutex_unlock(_mutex);
5322         assert (status == 0, "invariant") ;
5323      } else {
5324         status = pthread_mutex_unlock(_mutex);
5325         assert (status == 0, "invariant") ;
5326         status = pthread_cond_signal (_cond) ;
5327         assert (status == 0, "invariant") ;
5328      }
5329   } else {
5330     pthread_mutex_unlock(_mutex);
5331     assert (status == 0, "invariant") ;
5332   }
5333 }
5334 
5335 
5336 extern char** environ;
5337 
5338 #ifndef __NR_fork
5339 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
5340 #endif
5341 
5342 #ifndef __NR_execve
5343 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
5344 #endif
5345 
5346 // Run the specified command in a separate process. Return its exit value,
5347 // or -1 on failure (e.g. can't fork a new process).
5348 // Unlike system(), this function can be called from signal handler. It
5349 // doesn't block SIGINT et al.
5350 int os::fork_and_exec(char* cmd) {
5351   const char * argv[4] = {"sh", "-c", cmd, NULL};
5352 
5353   // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
5354   // pthread_atfork handlers and reset pthread library. All we need is a
5355   // separate process to execve. Make a direct syscall to fork process.
5356   // On IA64 there's no fork syscall, we have to use fork() and hope for
5357   // the best...
5358   pid_t pid = NOT_IA64(syscall(__NR_fork);)
5359               IA64_ONLY(fork();)
5360 
5361   if (pid < 0) {
5362     // fork failed
5363     return -1;
5364 
5365   } else if (pid == 0) {
5366     // child process
5367 
5368     // execve() in LinuxThreads will call pthread_kill_other_threads_np()
5369     // first to kill every thread on the thread list. Because this list is
5370     // not reset by fork() (see notes above), execve() will instead kill
5371     // every thread in the parent process. We know this is the only thread
5372     // in the new process, so make a system call directly.
5373     // IA64 should use normal execve() from glibc to match the glibc fork()
5374     // above.
5375     NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
5376     IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
5377 
5378     // execve failed
5379     _exit(-1);
5380 
5381   } else  {
5382     // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5383     // care about the actual exit code, for now.
5384 
5385     int status;
5386 
5387     // Wait for the child process to exit.  This returns immediately if
5388     // the child has already exited. */
5389     while (waitpid(pid, &status, 0) < 0) {
5390         switch (errno) {
5391         case ECHILD: return 0;
5392         case EINTR: break;
5393         default: return -1;
5394         }
5395     }
5396 
5397     if (WIFEXITED(status)) {
5398        // The child exited normally; get its exit code.
5399        return WEXITSTATUS(status);
5400     } else if (WIFSIGNALED(status)) {
5401        // The child exited because of a signal
5402        // The best value to return is 0x80 + signal number,
5403        // because that is what all Unix shells do, and because
5404        // it allows callers to distinguish between process exit and
5405        // process death by signal.
5406        return 0x80 + WTERMSIG(status);
5407     } else {
5408        // Unknown exit code; pass it through
5409        return status;
5410     }
5411   }
5412 }
5413 
5414 // is_headless_jre()
5415 //
5416 // Test for the existence of libmawt in motif21 or xawt directories
5417 // in order to report if we are running in a headless jre
5418 //
5419 bool os::is_headless_jre() {
5420     struct stat statbuf;
5421     char buf[MAXPATHLEN];
5422     char libmawtpath[MAXPATHLEN];
5423     const char *xawtstr  = "/xawt/libmawt.so";
5424     const char *motifstr = "/motif21/libmawt.so";
5425     char *p;
5426 
5427     // Get path to libjvm.so
5428     os::jvm_path(buf, sizeof(buf));
5429 
5430     // Get rid of libjvm.so
5431     p = strrchr(buf, '/');
5432     if (p == NULL) return false;
5433     else *p = '\0';
5434 
5435     // Get rid of client or server
5436     p = strrchr(buf, '/');
5437     if (p == NULL) return false;
5438     else *p = '\0';
5439 
5440     // check xawt/libmawt.so
5441     strcpy(libmawtpath, buf);
5442     strcat(libmawtpath, xawtstr);
5443     if (::stat(libmawtpath, &statbuf) == 0) return false;
5444 
5445     // check motif21/libmawt.so
5446     strcpy(libmawtpath, buf);
5447     strcat(libmawtpath, motifstr);
5448     if (::stat(libmawtpath, &statbuf) == 0) return false;
5449 
5450     return true;
5451 }
5452 
5453 
5454 #ifdef JAVASE_EMBEDDED
5455 //
5456 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory.
5457 //
5458 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL;
5459 
5460 // ctor
5461 //
5462 MemNotifyThread::MemNotifyThread(int fd): Thread() {
5463   assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread");
5464   _fd = fd;
5465 
5466   if (os::create_thread(this, os::os_thread)) {
5467     _memnotify_thread = this;
5468     os::set_priority(this, NearMaxPriority);
5469     os::start_thread(this);
5470   }
5471 }
5472 
5473 // Where all the work gets done
5474 //
5475 void MemNotifyThread::run() {
5476   assert(this == memnotify_thread(), "expected the singleton MemNotifyThread");
5477 
5478   // Set up the select arguments
5479   fd_set rfds;
5480   if (_fd != -1) {
5481     FD_ZERO(&rfds);
5482     FD_SET(_fd, &rfds);
5483   }
5484 
5485   // Now wait for the mem_notify device to wake up
5486   while (1) {
5487     // Wait for the mem_notify device to signal us..
5488     int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL);
5489     if (rc == -1) {
5490       perror("select!\n");
5491       break;
5492     } else if (rc) {
5493       //ssize_t free_before = os::available_memory();
5494       //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024);
5495 
5496       // The kernel is telling us there is not much memory left...
5497       // try to do something about that
5498 
5499       // If we are not already in a GC, try one.
5500       if (!Universe::heap()->is_gc_active()) {
5501         Universe::heap()->collect(GCCause::_allocation_failure);
5502 
5503         //ssize_t free_after = os::available_memory();
5504         //tty->print ("Post-Notify: Free: %dK\n",free_after/1024);
5505         //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024);
5506       }
5507       // We might want to do something like the following if we find the GC's are not helping...
5508       // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true);
5509     }
5510   }
5511 }
5512 
5513 //
5514 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it.
5515 //
5516 void MemNotifyThread::start() {
5517   int    fd;
5518   fd = open ("/dev/mem_notify", O_RDONLY, 0);
5519   if (fd < 0) {
5520       return;
5521   }
5522 
5523   if (memnotify_thread() == NULL) {
5524     new MemNotifyThread(fd);
5525   }
5526 }
5527 #endif // JAVASE_EMBEDDED
--- EOF ---