jdk8-mips64-public/hotspot: src/os/bsd/vm/os_bsd.cpp@2d23269a45a0 (annotated)

src/os/bsd/vm/os_bsd.cpp@2d23269a45a0 (annotated)

src/os/bsd/vm/os_bsd.cpp

Wed, 04 Nov 2015 16:23:08 -0800

author: clanger
date: Wed, 04 Nov 2015 16:23:08 -0800
changeset 8210: 2d23269a45a0
parent 7824: bbceafdc7a5f
child 7994: 04ff2f6cd0eb
child 9060: 438da598a947
permissions: -rw-r--r--

8140244: Port fix of JDK-8075773 to AIX and possibly MacOSX
Reviewed-by: stuefe, dcubed

 /*
  * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 // no precompiled headers
 #include "classfile/classLoader.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmSymbols.hpp"
 #include "code/icBuffer.hpp"
 #include "code/vtableStubs.hpp"
 #include "compiler/compileBroker.hpp"
 #include "compiler/disassembler.hpp"
 #include "interpreter/interpreter.hpp"
 #include "jvm_bsd.h"
 #include "memory/allocation.inline.hpp"
 #include "memory/filemap.hpp"
 #include "mutex_bsd.inline.hpp"
 #include "oops/oop.inline.hpp"
 #include "os_share_bsd.hpp"
 #include "prims/jniFastGetField.hpp"
 #include "prims/jvm.h"
 #include "prims/jvm_misc.hpp"
 #include "runtime/arguments.hpp"
 #include "runtime/extendedPC.hpp"
 #include "runtime/globals.hpp"
 #include "runtime/interfaceSupport.hpp"
 #include "runtime/java.hpp"
 #include "runtime/javaCalls.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "runtime/objectMonitor.hpp"
 #include "runtime/orderAccess.inline.hpp"
 #include "runtime/osThread.hpp"
 #include "runtime/perfMemory.hpp"
 #include "runtime/sharedRuntime.hpp"
 #include "runtime/statSampler.hpp"
 #include "runtime/stubRoutines.hpp"
 #include "runtime/thread.inline.hpp"
 #include "runtime/threadCritical.hpp"
 #include "runtime/timer.hpp"
 #include "services/attachListener.hpp"
 #include "services/memTracker.hpp"
 #include "services/runtimeService.hpp"
 #include "utilities/decoder.hpp"
 #include "utilities/defaultStream.hpp"
 #include "utilities/events.hpp"
 #include "utilities/growableArray.hpp"
 #include "utilities/vmError.hpp"
 // put OS-includes here
 # include <sys/types.h>
 # include <sys/mman.h>
 # include <sys/stat.h>
 # include <sys/select.h>
 # include <pthread.h>
 # include <signal.h>
 # include <errno.h>
 # include <dlfcn.h>
 # include <stdio.h>
 # include <unistd.h>
 # include <sys/resource.h>
 # include <pthread.h>
 # include <sys/stat.h>
 # include <sys/time.h>
 # include <sys/times.h>
 # include <sys/utsname.h>
 # include <sys/socket.h>
 # include <sys/wait.h>
 # include <time.h>
 # include <pwd.h>
 # include <poll.h>
 # include <semaphore.h>
 # include <fcntl.h>
 # include <string.h>
 # include <sys/param.h>
 # include <sys/sysctl.h>
 # include <sys/ipc.h>
 # include <sys/shm.h>
 #ifndef __APPLE__
 # include <link.h>
 #endif
 # include <stdint.h>
 # include <inttypes.h>
 # include <sys/ioctl.h>
 # include <sys/syscall.h>
 #if defined(__FreeBSD__) || defined(__NetBSD__)
 # include <elf.h>
 #endif
 #ifdef __APPLE__
 # include <mach/mach.h> // semaphore_* API
 # include <mach-o/dyld.h>
 # include <sys/proc_info.h>
 # include <objc/objc-auto.h>
 #endif
 #ifndef MAP_ANONYMOUS
 #define MAP_ANONYMOUS MAP_ANON
 #endif
 #define MAX_PATH    (2 * K)
 // for timer info max values which include all bits
 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
 #define LARGEPAGES_BIT (1 << 6)
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 ////////////////////////////////////////////////////////////////////////////////
 // global variables
 julong os::Bsd::_physical_memory = 0;
 #ifdef __APPLE__
 mach_timebase_info_data_t os::Bsd::_timebase_info = {0, 0};
 volatile uint64_t         os::Bsd::_max_abstime   = 0;
 #else
 int (*os::Bsd::_clock_gettime)(clockid_t, struct timespec *) = NULL;
 #endif
 pthread_t os::Bsd::_main_thread;
 int os::Bsd::_page_size = -1;
 static jlong initial_time_count=0;
 static int clock_tics_per_sec = 100;
 // For diagnostics to print a message once. see run_periodic_checks
 static sigset_t check_signal_done;
 static bool check_signals = true;
 static pid_t _initial_pid = 0;
 /* Signal number used to suspend/resume a thread */
 /* do not use any signal number less than SIGSEGV, see 4355769 */
 static int SR_signum = SIGUSR2;
 sigset_t SR_sigset;
 ////////////////////////////////////////////////////////////////////////////////
 // utility functions
 static int SR_initialize();
 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
 julong os::available_memory() {
   return Bsd::available_memory();
 }
 // available here means free
 julong os::Bsd::available_memory() {
   uint64_t available = physical_memory() >> 2;
 #ifdef __APPLE__
   mach_msg_type_number_t count = HOST_VM_INFO64_COUNT;
   vm_statistics64_data_t vmstat;
   kern_return_t kerr = host_statistics64(mach_host_self(), HOST_VM_INFO64,
                                          (host_info64_t)&vmstat, &count);
   assert(kerr == KERN_SUCCESS,
          "host_statistics64 failed - check mach_host_self() and count");
   if (kerr == KERN_SUCCESS) {
     available = vmstat.free_count * os::vm_page_size();
   }
 #endif
   return available;
 }
 julong os::physical_memory() {
   return Bsd::physical_memory();
 }
 ////////////////////////////////////////////////////////////////////////////////
 // environment support
 bool os::getenv(const char* name, char* buf, int len) {
   const char* val = ::getenv(name);
   if (val != NULL && strlen(val) < (size_t)len) {
     strcpy(buf, val);
     return true;
   }
   if (len > 0) buf[0] = 0;  // return a null string
   return false;
 }
 // Return true if user is running as root.
 bool os::have_special_privileges() {
   static bool init = false;
   static bool privileges = false;
   if (!init) {
     privileges = (getuid() != geteuid()) || (getgid() != getegid());
     init = true;
   }
   return privileges;
 }
 // Cpu architecture string
 #if   defined(ZERO)
 static char cpu_arch[] = ZERO_LIBARCH;
 #elif defined(IA64)
 static char cpu_arch[] = "ia64";
 #elif defined(IA32)
 static char cpu_arch[] = "i386";
 #elif defined(AMD64)
 static char cpu_arch[] = "amd64";
 #elif defined(ARM)
 static char cpu_arch[] = "arm";
 #elif defined(PPC32)
 static char cpu_arch[] = "ppc";
 #elif defined(SPARC)
 #  ifdef _LP64
 static char cpu_arch[] = "sparcv9";
 #  else
 static char cpu_arch[] = "sparc";
 #  endif
 #else
 #error Add appropriate cpu_arch setting
 #endif
 // Compiler variant
 #ifdef COMPILER2
 #define COMPILER_VARIANT "server"
 #else
 #define COMPILER_VARIANT "client"
 #endif
 void os::Bsd::initialize_system_info() {
   int mib[2];
   size_t len;
   int cpu_val;
   julong mem_val;
   /* get processors count via hw.ncpus sysctl */
   mib[0] = CTL_HW;
   mib[1] = HW_NCPU;
   len = sizeof(cpu_val);
   if (sysctl(mib, 2, &cpu_val, &len, NULL, 0) != -1 && cpu_val >= 1) {
        assert(len == sizeof(cpu_val), "unexpected data size");
        set_processor_count(cpu_val);
   }
   else {
        set_processor_count(1);   // fallback
   }
   /* get physical memory via hw.memsize sysctl (hw.memsize is used
    * since it returns a 64 bit value)
    */
   mib[0] = CTL_HW;
 #if defined (HW_MEMSIZE) // Apple
   mib[1] = HW_MEMSIZE;
 #elif defined(HW_PHYSMEM) // Most of BSD
   mib[1] = HW_PHYSMEM;
 #elif defined(HW_REALMEM) // Old FreeBSD
   mib[1] = HW_REALMEM;
 #else
   #error No ways to get physmem
 #endif
   len = sizeof(mem_val);
   if (sysctl(mib, 2, &mem_val, &len, NULL, 0) != -1) {
        assert(len == sizeof(mem_val), "unexpected data size");
        _physical_memory = mem_val;
   } else {
        _physical_memory = 256*1024*1024;       // fallback (XXXBSD?)
   }
 #ifdef __OpenBSD__
   {
        // limit _physical_memory memory view on OpenBSD since
        // datasize rlimit restricts us anyway.
        struct rlimit limits;
        getrlimit(RLIMIT_DATA, &limits);
        _physical_memory = MIN2(_physical_memory, (julong)limits.rlim_cur);
   }
 #endif
 }
 #ifdef __APPLE__
 static const char *get_home() {
   const char *home_dir = ::getenv("HOME");
   if ((home_dir == NULL) || (*home_dir == '\0')) {
     struct passwd *passwd_info = getpwuid(geteuid());
     if (passwd_info != NULL) {
       home_dir = passwd_info->pw_dir;
     }
   }
   return home_dir;
 }
 #endif
 void os::init_system_properties_values() {
   // The next steps are taken in the product version:
   //
   // Obtain the JAVA_HOME value from the location of libjvm.so.
   // This library should be located at:
   // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
   //
   // If "/jre/lib/" appears at the right place in the path, then we
   // assume libjvm.so is installed in a JDK and we use this path.
   //
   // Otherwise exit with message: "Could not create the Java virtual machine."
   //
   // The following extra steps are taken in the debugging version:
   //
   // If "/jre/lib/" does NOT appear at the right place in the path
   // instead of exit check for $JAVA_HOME environment variable.
   //
   // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
   // then we append a fake suffix "hotspot/libjvm.so" to this path so
   // it looks like libjvm.so is installed there
   // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
   //
   // Otherwise exit.
   //
   // Important note: if the location of libjvm.so changes this
   // code needs to be changed accordingly.
 // See ld(1):
 //      The linker uses the following search paths to locate required
 //      shared libraries:
 //        1: ...
 //        ...
 //        7: The default directories, normally /lib and /usr/lib.
 #ifndef DEFAULT_LIBPATH
 #define DEFAULT_LIBPATH "/lib:/usr/lib"
 #endif
 // Base path of extensions installed on the system.
 #define SYS_EXT_DIR     "/usr/java/packages"
 #define EXTENSIONS_DIR  "/lib/ext"
 #define ENDORSED_DIR    "/lib/endorsed"
 #ifndef __APPLE__
   // Buffer that fits several sprintfs.
   // Note that the space for the colon and the trailing null are provided
   // by the nulls included by the sizeof operator.
   const size_t bufsize =
     MAX3((size_t)MAXPATHLEN,  // For dll_dir & friends.
          (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir
          (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir
   char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
   // sysclasspath, java_home, dll_dir
   {
     char *pslash;
     os::jvm_path(buf, bufsize);
     // Found the full path to libjvm.so.
     // Now cut the path to <java_home>/jre if we can.
     *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so.
     pslash = strrchr(buf, '/');
     if (pslash != NULL) {
       *pslash = '\0';            // Get rid of /{client|server|hotspot}.
     }
     Arguments::set_dll_dir(buf);
     if (pslash != NULL) {
       pslash = strrchr(buf, '/');
       if (pslash != NULL) {
         *pslash = '\0';          // Get rid of /<arch>.
         pslash = strrchr(buf, '/');
         if (pslash != NULL) {
           *pslash = '\0';        // Get rid of /lib.
         }
       }
     }
     Arguments::set_java_home(buf);
     set_boot_path('/', ':');
   }
   // Where to look for native libraries.
   //
   // Note: Due to a legacy implementation, most of the library path
   // is set in the launcher. This was to accomodate linking restrictions
   // on legacy Bsd implementations (which are no longer supported).
   // Eventually, all the library path setting will be done here.
   //
   // However, to prevent the proliferation of improperly built native
   // libraries, the new path component /usr/java/packages is added here.
   // Eventually, all the library path setting will be done here.
   {
     // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
     // should always exist (until the legacy problem cited above is
     // addressed).
     const char *v = ::getenv("LD_LIBRARY_PATH");
     const char *v_colon = ":";
     if (v == NULL) { v = ""; v_colon = ""; }
     // That's +1 for the colon and +1 for the trailing '\0'.
     char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
                                                      strlen(v) + 1 +
                                                      sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
                                                      mtInternal);
     sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
     Arguments::set_library_path(ld_library_path);
     FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal);
   }
   // Extensions directories.
   sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
   Arguments::set_ext_dirs(buf);
   // Endorsed standards default directory.
   sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
   Arguments::set_endorsed_dirs(buf);
   FREE_C_HEAP_ARRAY(char, buf, mtInternal);
 #else // __APPLE__
 #define SYS_EXTENSIONS_DIR   "/Library/Java/Extensions"
 #define SYS_EXTENSIONS_DIRS  SYS_EXTENSIONS_DIR ":/Network" SYS_EXTENSIONS_DIR ":/System" SYS_EXTENSIONS_DIR ":/usr/lib/java"
   const char *user_home_dir = get_home();
   // The null in SYS_EXTENSIONS_DIRS counts for the size of the colon after user_home_dir.
   size_t system_ext_size = strlen(user_home_dir) + sizeof(SYS_EXTENSIONS_DIR) +
     sizeof(SYS_EXTENSIONS_DIRS);
   // Buffer that fits several sprintfs.
   // Note that the space for the colon and the trailing null are provided
   // by the nulls included by the sizeof operator.
   const size_t bufsize =
     MAX3((size_t)MAXPATHLEN,  // for dll_dir & friends.
          (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + system_ext_size, // extensions dir
          (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir
   char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
   // sysclasspath, java_home, dll_dir
   {
     char *pslash;
     os::jvm_path(buf, bufsize);
     // Found the full path to libjvm.so.
     // Now cut the path to <java_home>/jre if we can.
     *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so.
     pslash = strrchr(buf, '/');
     if (pslash != NULL) {
       *pslash = '\0';            // Get rid of /{client|server|hotspot}.
     }
     Arguments::set_dll_dir(buf);
     if (pslash != NULL) {
       pslash = strrchr(buf, '/');
       if (pslash != NULL) {
         *pslash = '\0';          // Get rid of /lib.
       }
     }
     Arguments::set_java_home(buf);
     set_boot_path('/', ':');
   }
   // Where to look for native libraries.
   //
   // Note: Due to a legacy implementation, most of the library path
   // is set in the launcher. This was to accomodate linking restrictions
   // on legacy Bsd implementations (which are no longer supported).
   // Eventually, all the library path setting will be done here.
   //
   // However, to prevent the proliferation of improperly built native
   // libraries, the new path component /usr/java/packages is added here.
   // Eventually, all the library path setting will be done here.
   {
     // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
     // should always exist (until the legacy problem cited above is
     // addressed).
     // Prepend the default path with the JAVA_LIBRARY_PATH so that the app launcher code
     // can specify a directory inside an app wrapper
     const char *l = ::getenv("JAVA_LIBRARY_PATH");
     const char *l_colon = ":";
     if (l == NULL) { l = ""; l_colon = ""; }
     const char *v = ::getenv("DYLD_LIBRARY_PATH");
     const char *v_colon = ":";
     if (v == NULL) { v = ""; v_colon = ""; }
     // Apple's Java6 has "." at the beginning of java.library.path.
     // OpenJDK on Windows has "." at the end of java.library.path.
     // OpenJDK on Linux and Solaris don't have "." in java.library.path
     // at all. To ease the transition from Apple's Java6 to OpenJDK7,
     // "." is appended to the end of java.library.path. Yes, this
     // could cause a change in behavior, but Apple's Java6 behavior
     // can be achieved by putting "." at the beginning of the
     // JAVA_LIBRARY_PATH environment variable.
     char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
                                                      strlen(v) + 1 + strlen(l) + 1 +
                                                      system_ext_size + 3,
                                                      mtInternal);
     sprintf(ld_library_path, "%s%s%s%s%s" SYS_EXTENSIONS_DIR ":" SYS_EXTENSIONS_DIRS ":.",
             v, v_colon, l, l_colon, user_home_dir);
     Arguments::set_library_path(ld_library_path);
     FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal);
   }
   // Extensions directories.
   //
   // Note that the space for the colon and the trailing null are provided
   // by the nulls included by the sizeof operator (so actually one byte more
   // than necessary is allocated).
   sprintf(buf, "%s" SYS_EXTENSIONS_DIR ":%s" EXTENSIONS_DIR ":" SYS_EXTENSIONS_DIRS,
           user_home_dir, Arguments::get_java_home());
   Arguments::set_ext_dirs(buf);
   // Endorsed standards default directory.
   sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
   Arguments::set_endorsed_dirs(buf);
   FREE_C_HEAP_ARRAY(char, buf, mtInternal);
 #undef SYS_EXTENSIONS_DIR
 #undef SYS_EXTENSIONS_DIRS
 #endif // __APPLE__
 #undef SYS_EXT_DIR
 #undef EXTENSIONS_DIR
 #undef ENDORSED_DIR
 }
 ////////////////////////////////////////////////////////////////////////////////
 // breakpoint support
 void os::breakpoint() {
   BREAKPOINT;
 }
 extern "C" void breakpoint() {
   // use debugger to set breakpoint here
 }
 ////////////////////////////////////////////////////////////////////////////////
 // signal support
 debug_only(static bool signal_sets_initialized = false);
 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
 bool os::Bsd::is_sig_ignored(int sig) {
       struct sigaction oact;
       sigaction(sig, (struct sigaction*)NULL, &oact);
       void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*,  oact.sa_sigaction)
                                      : CAST_FROM_FN_PTR(void*,  oact.sa_handler);
       if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
            return true;
       else
            return false;
 }
 void os::Bsd::signal_sets_init() {
   // Should also have an assertion stating we are still single-threaded.
   assert(!signal_sets_initialized, "Already initialized");
   // Fill in signals that are necessarily unblocked for all threads in
   // the VM. Currently, we unblock the following signals:
   // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
   //                         by -Xrs (=ReduceSignalUsage));
   // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
   // other threads. The "ReduceSignalUsage" boolean tells us not to alter
   // the dispositions or masks wrt these signals.
   // Programs embedding the VM that want to use the above signals for their
   // own purposes must, at this time, use the "-Xrs" option to prevent
   // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
   // (See bug 4345157, and other related bugs).
   // In reality, though, unblocking these signals is really a nop, since
   // these signals are not blocked by default.
   sigemptyset(&unblocked_sigs);
   sigemptyset(&allowdebug_blocked_sigs);
   sigaddset(&unblocked_sigs, SIGILL);
   sigaddset(&unblocked_sigs, SIGSEGV);
   sigaddset(&unblocked_sigs, SIGBUS);
   sigaddset(&unblocked_sigs, SIGFPE);
   sigaddset(&unblocked_sigs, SR_signum);
   if (!ReduceSignalUsage) {
    if (!os::Bsd::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
       sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
       sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
    }
    if (!os::Bsd::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
       sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
       sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
    }
    if (!os::Bsd::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
       sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
       sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
    }
   }
   // Fill in signals that are blocked by all but the VM thread.
   sigemptyset(&vm_sigs);
   if (!ReduceSignalUsage)
     sigaddset(&vm_sigs, BREAK_SIGNAL);
   debug_only(signal_sets_initialized = true);
 }
 // These are signals that are unblocked while a thread is running Java.
 // (For some reason, they get blocked by default.)
 sigset_t* os::Bsd::unblocked_signals() {
   assert(signal_sets_initialized, "Not initialized");
   return &unblocked_sigs;
 }
 // These are the signals that are blocked while a (non-VM) thread is
 // running Java. Only the VM thread handles these signals.
 sigset_t* os::Bsd::vm_signals() {
   assert(signal_sets_initialized, "Not initialized");
   return &vm_sigs;
 }
 // These are signals that are blocked during cond_wait to allow debugger in
 sigset_t* os::Bsd::allowdebug_blocked_signals() {
   assert(signal_sets_initialized, "Not initialized");
   return &allowdebug_blocked_sigs;
 }
 void os::Bsd::hotspot_sigmask(Thread* thread) {
   //Save caller's signal mask before setting VM signal mask
   sigset_t caller_sigmask;
   pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
   OSThread* osthread = thread->osthread();
   osthread->set_caller_sigmask(caller_sigmask);
   pthread_sigmask(SIG_UNBLOCK, os::Bsd::unblocked_signals(), NULL);
   if (!ReduceSignalUsage) {
     if (thread->is_VM_thread()) {
       // Only the VM thread handles BREAK_SIGNAL ...
       pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
     } else {
       // ... all other threads block BREAK_SIGNAL
       pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
     }
   }
 }
 //////////////////////////////////////////////////////////////////////////////
 // create new thread
 // check if it's safe to start a new thread
 static bool _thread_safety_check(Thread* thread) {
   return true;
 }
 #ifdef __APPLE__
 // library handle for calling objc_registerThreadWithCollector()
 // without static linking to the libobjc library
 #define OBJC_LIB "/usr/lib/libobjc.dylib"
 #define OBJC_GCREGISTER "objc_registerThreadWithCollector"
 typedef void (*objc_registerThreadWithCollector_t)();
 extern "C" objc_registerThreadWithCollector_t objc_registerThreadWithCollectorFunction;
 objc_registerThreadWithCollector_t objc_registerThreadWithCollectorFunction = NULL;
 #endif
 #ifdef __APPLE__
 static uint64_t locate_unique_thread_id(mach_port_t mach_thread_port) {
   // Additional thread_id used to correlate threads in SA
   thread_identifier_info_data_t     m_ident_info;
   mach_msg_type_number_t            count = THREAD_IDENTIFIER_INFO_COUNT;
   thread_info(mach_thread_port, THREAD_IDENTIFIER_INFO,
               (thread_info_t) &m_ident_info, &count);
   return m_ident_info.thread_id;
 }
 #endif
 // Thread start routine for all newly created threads
 static void *java_start(Thread *thread) {
   // Try to randomize the cache line index of hot stack frames.
   // This helps when threads of the same stack traces evict each other's
   // cache lines. The threads can be either from the same JVM instance, or
   // from different JVM instances. The benefit is especially true for
   // processors with hyperthreading technology.
   static int counter = 0;
   int pid = os::current_process_id();
   alloca(((pid ^ counter++) & 7) * 128);
   ThreadLocalStorage::set_thread(thread);
   OSThread* osthread = thread->osthread();
   Monitor* sync = osthread->startThread_lock();
   // non floating stack BsdThreads needs extra check, see above
   if (!_thread_safety_check(thread)) {
     // notify parent thread
     MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
     osthread->set_state(ZOMBIE);
     sync->notify_all();
     return NULL;
   }
   osthread->set_thread_id(os::Bsd::gettid());
 #ifdef __APPLE__
   uint64_t unique_thread_id = locate_unique_thread_id(osthread->thread_id());
   guarantee(unique_thread_id != 0, "unique thread id was not found");
   osthread->set_unique_thread_id(unique_thread_id);
 #endif
   // initialize signal mask for this thread
   os::Bsd::hotspot_sigmask(thread);
   // initialize floating point control register
   os::Bsd::init_thread_fpu_state();
 #ifdef __APPLE__
   // register thread with objc gc
   if (objc_registerThreadWithCollectorFunction != NULL) {
     objc_registerThreadWithCollectorFunction();
   }
 #endif
   // handshaking with parent thread
   {
     MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
     // notify parent thread
     osthread->set_state(INITIALIZED);
     sync->notify_all();
     // wait until os::start_thread()
     while (osthread->get_state() == INITIALIZED) {
       sync->wait(Mutex::_no_safepoint_check_flag);
     }
   }
   // call one more level start routine
   thread->run();
   return 0;
 }
 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
   assert(thread->osthread() == NULL, "caller responsible");
   // Allocate the OSThread object
   OSThread* osthread = new OSThread(NULL, NULL);
   if (osthread == NULL) {
     return false;
   }
   // set the correct thread state
   osthread->set_thread_type(thr_type);
   // Initial state is ALLOCATED but not INITIALIZED
   osthread->set_state(ALLOCATED);
   thread->set_osthread(osthread);
   // init thread attributes
   pthread_attr_t attr;
   pthread_attr_init(&attr);
   pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
   // stack size
   if (os::Bsd::supports_variable_stack_size()) {
     // calculate stack size if it's not specified by caller
     if (stack_size == 0) {
       stack_size = os::Bsd::default_stack_size(thr_type);
       switch (thr_type) {
       case os::java_thread:
         // Java threads use ThreadStackSize which default value can be
         // changed with the flag -Xss
         assert (JavaThread::stack_size_at_create() > 0, "this should be set");
         stack_size = JavaThread::stack_size_at_create();
         break;
       case os::compiler_thread:
         if (CompilerThreadStackSize > 0) {
           stack_size = (size_t)(CompilerThreadStackSize * K);
           break;
         } // else fall through:
           // use VMThreadStackSize if CompilerThreadStackSize is not defined
       case os::vm_thread:
       case os::pgc_thread:
       case os::cgc_thread:
       case os::watcher_thread:
         if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
         break;
       }
     }
     stack_size = MAX2(stack_size, os::Bsd::min_stack_allowed);
     pthread_attr_setstacksize(&attr, stack_size);
   } else {
     // let pthread_create() pick the default value.
   }
   ThreadState state;
   {
     pthread_t tid;
     int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
     pthread_attr_destroy(&attr);
     if (ret != 0) {
       if (PrintMiscellaneous && (Verbose || WizardMode)) {
         perror("pthread_create()");
       }
       // Need to clean up stuff we've allocated so far
       thread->set_osthread(NULL);
       delete osthread;
       return false;
     }
     // Store pthread info into the OSThread
     osthread->set_pthread_id(tid);
     // Wait until child thread is either initialized or aborted
     {
       Monitor* sync_with_child = osthread->startThread_lock();
       MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
       while ((state = osthread->get_state()) == ALLOCATED) {
         sync_with_child->wait(Mutex::_no_safepoint_check_flag);
       }
     }
   }
   // Aborted due to thread limit being reached
   if (state == ZOMBIE) {
       thread->set_osthread(NULL);
       delete osthread;
       return false;
   }
   // The thread is returned suspended (in state INITIALIZED),
   // and is started higher up in the call chain
   assert(state == INITIALIZED, "race condition");
   return true;
 }
 /////////////////////////////////////////////////////////////////////////////
 // attach existing thread
 // bootstrap the main thread
 bool os::create_main_thread(JavaThread* thread) {
   assert(os::Bsd::_main_thread == pthread_self(), "should be called inside main thread");
   return create_attached_thread(thread);
 }
 bool os::create_attached_thread(JavaThread* thread) {
 #ifdef ASSERT
     thread->verify_not_published();
 #endif
   // Allocate the OSThread object
   OSThread* osthread = new OSThread(NULL, NULL);
   if (osthread == NULL) {
     return false;
   }
   osthread->set_thread_id(os::Bsd::gettid());
   // Store pthread info into the OSThread
 #ifdef __APPLE__
   uint64_t unique_thread_id = locate_unique_thread_id(osthread->thread_id());
   guarantee(unique_thread_id != 0, "just checking");
   osthread->set_unique_thread_id(unique_thread_id);
 #endif
   osthread->set_pthread_id(::pthread_self());
   // initialize floating point control register
   os::Bsd::init_thread_fpu_state();
   // Initial thread state is RUNNABLE
   osthread->set_state(RUNNABLE);
   thread->set_osthread(osthread);
   // initialize signal mask for this thread
   // and save the caller's signal mask
   os::Bsd::hotspot_sigmask(thread);
   return true;
 }
 void os::pd_start_thread(Thread* thread) {
   OSThread * osthread = thread->osthread();
   assert(osthread->get_state() != INITIALIZED, "just checking");
   Monitor* sync_with_child = osthread->startThread_lock();
   MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
   sync_with_child->notify();
 }
 // Free Bsd resources related to the OSThread
 void os::free_thread(OSThread* osthread) {
   assert(osthread != NULL, "osthread not set");
   if (Thread::current()->osthread() == osthread) {
     // Restore caller's signal mask
     sigset_t sigmask = osthread->caller_sigmask();
     pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
    }
   delete osthread;
 }
 //////////////////////////////////////////////////////////////////////////////
 // thread local storage
 // Restore the thread pointer if the destructor is called. This is in case
 // someone from JNI code sets up a destructor with pthread_key_create to run
 // detachCurrentThread on thread death. Unless we restore the thread pointer we
 // will hang or crash. When detachCurrentThread is called the key will be set
 // to null and we will not be called again. If detachCurrentThread is never
 // called we could loop forever depending on the pthread implementation.
 static void restore_thread_pointer(void* p) {
   Thread* thread = (Thread*) p;
   os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
 }
 int os::allocate_thread_local_storage() {
   pthread_key_t key;
   int rslt = pthread_key_create(&key, restore_thread_pointer);
   assert(rslt == 0, "cannot allocate thread local storage");
   return (int)key;
 }
 // Note: This is currently not used by VM, as we don't destroy TLS key
 // on VM exit.
 void os::free_thread_local_storage(int index) {
   int rslt = pthread_key_delete((pthread_key_t)index);
   assert(rslt == 0, "invalid index");
 }
 void os::thread_local_storage_at_put(int index, void* value) {
   int rslt = pthread_setspecific((pthread_key_t)index, value);
   assert(rslt == 0, "pthread_setspecific failed");
 }
 extern "C" Thread* get_thread() {
   return ThreadLocalStorage::thread();
 }
 ////////////////////////////////////////////////////////////////////////////////
 // time support
 // Time since start-up in seconds to a fine granularity.
 // Used by VMSelfDestructTimer and the MemProfiler.
 double os::elapsedTime() {
   return ((double)os::elapsed_counter()) / os::elapsed_frequency();
 }
 jlong os::elapsed_counter() {
   return javaTimeNanos() - initial_time_count;
 }
 jlong os::elapsed_frequency() {
   return NANOSECS_PER_SEC; // nanosecond resolution
 }
 bool os::supports_vtime() { return true; }
 bool os::enable_vtime()   { return false; }
 bool os::vtime_enabled()  { return false; }
 double os::elapsedVTime() {
   // better than nothing, but not much
   return elapsedTime();
 }
 jlong os::javaTimeMillis() {
   timeval time;
   int status = gettimeofday(&time, NULL);
   assert(status != -1, "bsd error");
   return jlong(time.tv_sec) * 1000  +  jlong(time.tv_usec / 1000);
 }
 #ifndef __APPLE__
 #ifndef CLOCK_MONOTONIC
 #define CLOCK_MONOTONIC (1)
 #endif
 #endif
 #ifdef __APPLE__
 void os::Bsd::clock_init() {
   mach_timebase_info(&_timebase_info);
 }
 #else
 void os::Bsd::clock_init() {
   struct timespec res;
   struct timespec tp;
   if (::clock_getres(CLOCK_MONOTONIC, &res) == 0 &&
       ::clock_gettime(CLOCK_MONOTONIC, &tp)  == 0) {
     // yes, monotonic clock is supported
     _clock_gettime = ::clock_gettime;
   }
 }
 #endif
 #ifdef __APPLE__
 jlong os::javaTimeNanos() {
     const uint64_t tm = mach_absolute_time();
     const uint64_t now = (tm * Bsd::_timebase_info.numer) / Bsd::_timebase_info.denom;
     const uint64_t prev = Bsd::_max_abstime;
     if (now <= prev) {
       return prev;   // same or retrograde time;
     }
     const uint64_t obsv = Atomic::cmpxchg(now, (volatile jlong*)&Bsd::_max_abstime, prev);
     assert(obsv >= prev, "invariant");   // Monotonicity
     // If the CAS succeeded then we're done and return "now".
     // If the CAS failed and the observed value "obsv" is >= now then
     // we should return "obsv".  If the CAS failed and now > obsv > prv then
     // some other thread raced this thread and installed a new value, in which case
     // we could either (a) retry the entire operation, (b) retry trying to install now
     // or (c) just return obsv.  We use (c).   No loop is required although in some cases
     // we might discard a higher "now" value in deference to a slightly lower but freshly
     // installed obsv value.   That's entirely benign -- it admits no new orderings compared
     // to (a) or (b) -- and greatly reduces coherence traffic.
     // We might also condition (c) on the magnitude of the delta between obsv and now.
     // Avoiding excessive CAS operations to hot RW locations is critical.
     // See https://blogs.oracle.com/dave/entry/cas_and_cache_trivia_invalidate
     return (prev == obsv) ? now : obsv;
 }
 #else // __APPLE__
 jlong os::javaTimeNanos() {
   if (Bsd::supports_monotonic_clock()) {
     struct timespec tp;
     int status = Bsd::_clock_gettime(CLOCK_MONOTONIC, &tp);
     assert(status == 0, "gettime error");
     jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
     return result;
   } else {
     timeval time;
     int status = gettimeofday(&time, NULL);
     assert(status != -1, "bsd error");
     jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
     return 1000 * usecs;
   }
 }
 #endif // __APPLE__
 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
   if (Bsd::supports_monotonic_clock()) {
     info_ptr->max_value = ALL_64_BITS;
     // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
     info_ptr->may_skip_backward = false;      // not subject to resetting or drifting
     info_ptr->may_skip_forward = false;       // not subject to resetting or drifting
   } else {
     // gettimeofday - based on time in seconds since the Epoch thus does not wrap
     info_ptr->max_value = ALL_64_BITS;
     // gettimeofday is a real time clock so it skips
     info_ptr->may_skip_backward = true;
     info_ptr->may_skip_forward = true;
   }
   info_ptr->kind = JVMTI_TIMER_ELAPSED;                // elapsed not CPU time
 }
 // Return the real, user, and system times in seconds from an
 // arbitrary fixed point in the past.
 bool os::getTimesSecs(double* process_real_time,
                       double* process_user_time,
                       double* process_system_time) {
   struct tms ticks;
   clock_t real_ticks = times(&ticks);
   if (real_ticks == (clock_t) (-1)) {
     return false;
   } else {
     double ticks_per_second = (double) clock_tics_per_sec;
     *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
     *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
     *process_real_time = ((double) real_ticks) / ticks_per_second;
     return true;
   }
 }
 char * os::local_time_string(char *buf, size_t buflen) {
   struct tm t;
   time_t long_time;
   time(&long_time);
   localtime_r(&long_time, &t);
   jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
                t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
                t.tm_hour, t.tm_min, t.tm_sec);
   return buf;
 }
 struct tm* os::localtime_pd(const time_t* clock, struct tm*  res) {
   return localtime_r(clock, res);
 }
 ////////////////////////////////////////////////////////////////////////////////
 // runtime exit support
 // Note: os::shutdown() might be called very early during initialization, or
 // called from signal handler. Before adding something to os::shutdown(), make
 // sure it is async-safe and can handle partially initialized VM.
 void os::shutdown() {
   // allow PerfMemory to attempt cleanup of any persistent resources
   perfMemory_exit();
   // needs to remove object in file system
   AttachListener::abort();
   // flush buffered output, finish log files
   ostream_abort();
   // Check for abort hook
   abort_hook_t abort_hook = Arguments::abort_hook();
   if (abort_hook != NULL) {
     abort_hook();
   }
 }
 // Note: os::abort() might be called very early during initialization, or
 // called from signal handler. Before adding something to os::abort(), make
 // sure it is async-safe and can handle partially initialized VM.
 void os::abort(bool dump_core) {
   os::shutdown();
   if (dump_core) {
 #ifndef PRODUCT
     fdStream out(defaultStream::output_fd());
     out.print_raw("Current thread is ");
     char buf[16];
     jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
     out.print_raw_cr(buf);
     out.print_raw_cr("Dumping core ...");
 #endif
     ::abort(); // dump core
   }
   ::exit(1);
 }
 // Die immediately, no exit hook, no abort hook, no cleanup.
 void os::die() {
   // _exit() on BsdThreads only kills current thread
   ::abort();
 }
 // This method is a copy of JDK's sysGetLastErrorString
 // from src/solaris/hpi/src/system_md.c
 size_t os::lasterror(char *buf, size_t len) {
   if (errno == 0)  return 0;
   const char *s = ::strerror(errno);
   size_t n = ::strlen(s);
   if (n >= len) {
     n = len - 1;
   }
   ::strncpy(buf, s, n);
   buf[n] = '\0';
   return n;
 }
 // Information of current thread in variety of formats
 pid_t os::Bsd::gettid() {
   int retval = -1;
 #ifdef __APPLE__ //XNU kernel
   // despite the fact mach port is actually not a thread id use it
   // instead of syscall(SYS_thread_selfid) as it certainly fits to u4
   retval = ::pthread_mach_thread_np(::pthread_self());
   guarantee(retval != 0, "just checking");
   return retval;
 #else
   #ifdef __FreeBSD__
   retval = syscall(SYS_thr_self);
   #else
     #ifdef __OpenBSD__
   retval = syscall(SYS_getthrid);
     #else
       #ifdef __NetBSD__
   retval = (pid_t) syscall(SYS__lwp_self);
       #endif
     #endif
   #endif
 #endif
   if (retval == -1) {
     return getpid();
   }
 }
 intx os::current_thread_id() {
 #ifdef __APPLE__
   return (intx)::pthread_mach_thread_np(::pthread_self());
 #else
   return (intx)::pthread_self();
 #endif
 }
 int os::current_process_id() {
   // Under the old bsd thread library, bsd gives each thread
   // its own process id. Because of this each thread will return
   // a different pid if this method were to return the result
   // of getpid(2). Bsd provides no api that returns the pid
   // of the launcher thread for the vm. This implementation
   // returns a unique pid, the pid of the launcher thread
   // that starts the vm 'process'.
   // Under the NPTL, getpid() returns the same pid as the
   // launcher thread rather than a unique pid per thread.
   // Use gettid() if you want the old pre NPTL behaviour.
   // if you are looking for the result of a call to getpid() that
   // returns a unique pid for the calling thread, then look at the
   // OSThread::thread_id() method in osThread_bsd.hpp file
   return (int)(_initial_pid ? _initial_pid : getpid());
 }
 // DLL functions
 #define JNI_LIB_PREFIX "lib"
 #ifdef __APPLE__
 #define JNI_LIB_SUFFIX ".dylib"
 #else
 #define JNI_LIB_SUFFIX ".so"
 #endif
 const char* os::dll_file_extension() { return JNI_LIB_SUFFIX; }
 // This must be hard coded because it's the system's temporary
 // directory not the java application's temp directory, ala java.io.tmpdir.
 #ifdef __APPLE__
 // macosx has a secure per-user temporary directory
 char temp_path_storage[PATH_MAX];
 const char* os::get_temp_directory() {
   static char *temp_path = NULL;
   if (temp_path == NULL) {
     int pathSize = confstr(_CS_DARWIN_USER_TEMP_DIR, temp_path_storage, PATH_MAX);
     if (pathSize == 0 || pathSize > PATH_MAX) {
       strlcpy(temp_path_storage, "/tmp/", sizeof(temp_path_storage));
     }
     temp_path = temp_path_storage;
   }
   return temp_path;
 }
 #else /* __APPLE__ */
 const char* os::get_temp_directory() { return "/tmp"; }
 #endif /* __APPLE__ */
 static bool file_exists(const char* filename) {
   struct stat statbuf;
   if (filename == NULL || strlen(filename) == 0) {
     return false;
   }
   return os::stat(filename, &statbuf) == 0;
 }
 bool os::dll_build_name(char* buffer, size_t buflen,
                         const char* pname, const char* fname) {
   bool retval = false;
   // Copied from libhpi
   const size_t pnamelen = pname ? strlen(pname) : 0;
   // Return error on buffer overflow.
   if (pnamelen + strlen(fname) + strlen(JNI_LIB_PREFIX) + strlen(JNI_LIB_SUFFIX) + 2 > buflen) {
     return retval;
   }
   if (pnamelen == 0) {
     snprintf(buffer, buflen, JNI_LIB_PREFIX "%s" JNI_LIB_SUFFIX, fname);
     retval = true;
   } else if (strchr(pname, *os::path_separator()) != NULL) {
     int n;
     char** pelements = split_path(pname, &n);
     if (pelements == NULL) {
       return false;
     }
     for (int i = 0 ; i < n ; i++) {
       // Really shouldn't be NULL, but check can't hurt
       if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
         continue; // skip the empty path values
       }
       snprintf(buffer, buflen, "%s/" JNI_LIB_PREFIX "%s" JNI_LIB_SUFFIX,
           pelements[i], fname);
       if (file_exists(buffer)) {
         retval = true;
         break;
       }
     }
     // release the storage
     for (int i = 0 ; i < n ; i++) {
       if (pelements[i] != NULL) {
         FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
       }
     }
     if (pelements != NULL) {
       FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
     }
   } else {
     snprintf(buffer, buflen, "%s/" JNI_LIB_PREFIX "%s" JNI_LIB_SUFFIX, pname, fname);
     retval = true;
   }
   return retval;
 }
 // check if addr is inside libjvm.so
 bool os::address_is_in_vm(address addr) {
   static address libjvm_base_addr;
   Dl_info dlinfo;
   if (libjvm_base_addr == NULL) {
     if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
       libjvm_base_addr = (address)dlinfo.dli_fbase;
     }
     assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
   }
   if (dladdr((void *)addr, &dlinfo) != 0) {
     if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
   }
   return false;
 }
 #define MACH_MAXSYMLEN 256
 bool os::dll_address_to_function_name(address addr, char *buf,
                                       int buflen, int *offset) {
   // buf is not optional, but offset is optional
   assert(buf != NULL, "sanity check");
   Dl_info dlinfo;
   char localbuf[MACH_MAXSYMLEN];
   if (dladdr((void*)addr, &dlinfo) != 0) {
     // see if we have a matching symbol
     if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
       if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
         jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
       }
       if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
       return true;
     }
     // no matching symbol so try for just file info
     if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
       if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
                           buf, buflen, offset, dlinfo.dli_fname)) {
          return true;
       }
     }
     // Handle non-dynamic manually:
     if (dlinfo.dli_fbase != NULL &&
         Decoder::decode(addr, localbuf, MACH_MAXSYMLEN, offset,
                         dlinfo.dli_fbase)) {
       if (!Decoder::demangle(localbuf, buf, buflen)) {
         jio_snprintf(buf, buflen, "%s", localbuf);
       }
       return true;
     }
   }
   buf[0] = '\0';
   if (offset != NULL) *offset = -1;
   return false;
 }
 // ported from solaris version
 bool os::dll_address_to_library_name(address addr, char* buf,
                                      int buflen, int* offset) {
   // buf is not optional, but offset is optional
   assert(buf != NULL, "sanity check");
   Dl_info dlinfo;
   if (dladdr((void*)addr, &dlinfo) != 0) {
     if (dlinfo.dli_fname != NULL) {
       jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
     }
     if (dlinfo.dli_fbase != NULL && offset != NULL) {
       *offset = addr - (address)dlinfo.dli_fbase;
     }
     return true;
   }
   buf[0] = '\0';
   if (offset) *offset = -1;
   return false;
 }
 // Loads .dll/.so and
 // in case of error it checks if .dll/.so was built for the
 // same architecture as Hotspot is running on
 #ifdef __APPLE__
 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) {
   void * result= ::dlopen(filename, RTLD_LAZY);
   if (result != NULL) {
     // Successful loading
     return result;
   }
   // Read system error message into ebuf
   ::strncpy(ebuf, ::dlerror(), ebuflen-1);
   ebuf[ebuflen-1]='\0';
   return NULL;
 }
 #else
 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
 {
   void * result= ::dlopen(filename, RTLD_LAZY);
   if (result != NULL) {
     // Successful loading
     return result;
   }
   Elf32_Ehdr elf_head;
   // Read system error message into ebuf
   // It may or may not be overwritten below
   ::strncpy(ebuf, ::dlerror(), ebuflen-1);
   ebuf[ebuflen-1]='\0';
   int diag_msg_max_length=ebuflen-strlen(ebuf);
   char* diag_msg_buf=ebuf+strlen(ebuf);
   if (diag_msg_max_length==0) {
     // No more space in ebuf for additional diagnostics message
     return NULL;
   }
   int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
   if (file_descriptor < 0) {
     // Can't open library, report dlerror() message
     return NULL;
   }
   bool failed_to_read_elf_head=
     (sizeof(elf_head)!=
         (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
   ::close(file_descriptor);
   if (failed_to_read_elf_head) {
     // file i/o error - report dlerror() msg
     return NULL;
   }
   typedef struct {
     Elf32_Half  code;         // Actual value as defined in elf.h
     Elf32_Half  compat_class; // Compatibility of archs at VM's sense
     char        elf_class;    // 32 or 64 bit
     char        endianess;    // MSB or LSB
     char*       name;         // String representation
   } arch_t;
   #ifndef EM_486
   #define EM_486          6               /* Intel 80486 */
   #endif
   #ifndef EM_MIPS_RS3_LE
   #define EM_MIPS_RS3_LE  10              /* MIPS */
   #endif
   #ifndef EM_PPC64
   #define EM_PPC64        21              /* PowerPC64 */
   #endif
   #ifndef EM_S390
   #define EM_S390         22              /* IBM System/390 */
   #endif
   #ifndef EM_IA_64
   #define EM_IA_64        50              /* HP/Intel IA-64 */
   #endif
   #ifndef EM_X86_64
   #define EM_X86_64       62              /* AMD x86-64 */
   #endif
   static const arch_t arch_array[]={
     {EM_386,         EM_386,     ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
     {EM_486,         EM_386,     ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
     {EM_IA_64,       EM_IA_64,   ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
     {EM_X86_64,      EM_X86_64,  ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
     {EM_SPARC,       EM_SPARC,   ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
     {EM_SPARC32PLUS, EM_SPARC,   ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
     {EM_SPARCV9,     EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
     {EM_PPC,         EM_PPC,     ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
     {EM_PPC64,       EM_PPC64,   ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
     {EM_ARM,         EM_ARM,     ELFCLASS32,   ELFDATA2LSB, (char*)"ARM"},
     {EM_S390,        EM_S390,    ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
     {EM_ALPHA,       EM_ALPHA,   ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
     {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
     {EM_MIPS,        EM_MIPS,    ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
     {EM_PARISC,      EM_PARISC,  ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
     {EM_68K,         EM_68K,     ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
   };
   #if  (defined IA32)
     static  Elf32_Half running_arch_code=EM_386;
   #elif   (defined AMD64)
     static  Elf32_Half running_arch_code=EM_X86_64;
   #elif  (defined IA64)
     static  Elf32_Half running_arch_code=EM_IA_64;
   #elif  (defined __sparc) && (defined _LP64)
     static  Elf32_Half running_arch_code=EM_SPARCV9;
   #elif  (defined __sparc) && (!defined _LP64)
     static  Elf32_Half running_arch_code=EM_SPARC;
   #elif  (defined __powerpc64__)
     static  Elf32_Half running_arch_code=EM_PPC64;
   #elif  (defined __powerpc__)
     static  Elf32_Half running_arch_code=EM_PPC;
   #elif  (defined ARM)
     static  Elf32_Half running_arch_code=EM_ARM;
   #elif  (defined S390)
     static  Elf32_Half running_arch_code=EM_S390;
   #elif  (defined ALPHA)
     static  Elf32_Half running_arch_code=EM_ALPHA;
   #elif  (defined MIPSEL)
     static  Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
   #elif  (defined PARISC)
     static  Elf32_Half running_arch_code=EM_PARISC;
   #elif  (defined MIPS)
     static  Elf32_Half running_arch_code=EM_MIPS;
   #elif  (defined M68K)
     static  Elf32_Half running_arch_code=EM_68K;
   #else
     #error Method os::dll_load requires that one of following is defined:\
          IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
   #endif
   // Identify compatability class for VM's architecture and library's architecture
   // Obtain string descriptions for architectures
   arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
   int running_arch_index=-1;
   for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
     if (running_arch_code == arch_array[i].code) {
       running_arch_index    = i;
     }
     if (lib_arch.code == arch_array[i].code) {
       lib_arch.compat_class = arch_array[i].compat_class;
       lib_arch.name         = arch_array[i].name;
     }
   }
   assert(running_arch_index != -1,
     "Didn't find running architecture code (running_arch_code) in arch_array");
   if (running_arch_index == -1) {
     // Even though running architecture detection failed
     // we may still continue with reporting dlerror() message
     return NULL;
   }
   if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
     ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
     return NULL;
   }
 #ifndef S390
   if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
     ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
     return NULL;
   }
 #endif // !S390
   if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
     if ( lib_arch.name!=NULL ) {
       ::snprintf(diag_msg_buf, diag_msg_max_length-1,
         " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
         lib_arch.name, arch_array[running_arch_index].name);
     } else {
       ::snprintf(diag_msg_buf, diag_msg_max_length-1,
       " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
         lib_arch.code,
         arch_array[running_arch_index].name);
     }
   }
   return NULL;
 }
 #endif /* !__APPLE__ */
 void* os::get_default_process_handle() {
 #ifdef __APPLE__
   // MacOS X needs to use RTLD_FIRST instead of RTLD_LAZY
   // to avoid finding unexpected symbols on second (or later)
   // loads of a library.
   return (void*)::dlopen(NULL, RTLD_FIRST);
 #else
   return (void*)::dlopen(NULL, RTLD_LAZY);
 #endif
 }
 // XXX: Do we need a lock around this as per Linux?
 void* os::dll_lookup(void* handle, const char* name) {
   return dlsym(handle, name);
 }
 static bool _print_ascii_file(const char* filename, outputStream* st) {
   int fd = ::open(filename, O_RDONLY);
   if (fd == -1) {
      return false;
   }
   char buf[32];
   int bytes;
   while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
     st->print_raw(buf, bytes);
   }
   ::close(fd);
   return true;
 }
 void os::print_dll_info(outputStream *st) {
   st->print_cr("Dynamic libraries:");
 #ifdef RTLD_DI_LINKMAP
   Dl_info dli;
   void *handle;
   Link_map *map;
   Link_map *p;
   if (dladdr(CAST_FROM_FN_PTR(void *, os::print_dll_info), &dli) == 0 ||
       dli.dli_fname == NULL) {
     st->print_cr("Error: Cannot print dynamic libraries.");
     return;
   }
   handle = dlopen(dli.dli_fname, RTLD_LAZY);
   if (handle == NULL) {
     st->print_cr("Error: Cannot print dynamic libraries.");
     return;
   }
   dlinfo(handle, RTLD_DI_LINKMAP, &map);
   if (map == NULL) {
     st->print_cr("Error: Cannot print dynamic libraries.");
     return;
   }
   while (map->l_prev != NULL)
     map = map->l_prev;
   while (map != NULL) {
     st->print_cr(PTR_FORMAT " \t%s", map->l_addr, map->l_name);
     map = map->l_next;
   }
   dlclose(handle);
 #elif defined(__APPLE__)
   uint32_t count;
   uint32_t i;
   count = _dyld_image_count();
   for (i = 1; i < count; i++) {
     const char *name = _dyld_get_image_name(i);
     intptr_t slide = _dyld_get_image_vmaddr_slide(i);
     st->print_cr(PTR_FORMAT " \t%s", slide, name);
   }
 #else
   st->print_cr("Error: Cannot print dynamic libraries.");
 #endif
 }
 void os::print_os_info_brief(outputStream* st) {
   st->print("Bsd");
   os::Posix::print_uname_info(st);
 }
 void os::print_os_info(outputStream* st) {
   st->print("OS:");
   st->print("Bsd");
   os::Posix::print_uname_info(st);
   os::Posix::print_rlimit_info(st);
   os::Posix::print_load_average(st);
 }
 void os::pd_print_cpu_info(outputStream* st) {
   // Nothing to do for now.
 }
 void os::print_memory_info(outputStream* st) {
   st->print("Memory:");
   st->print(" %dk page", os::vm_page_size()>>10);
   st->print(", physical " UINT64_FORMAT "k",
             os::physical_memory() >> 10);
   st->print("(" UINT64_FORMAT "k free)",
             os::available_memory() >> 10);
   st->cr();
   // meminfo
   st->print("\n/proc/meminfo:\n");
   _print_ascii_file("/proc/meminfo", st);
   st->cr();
 }
 void os::print_siginfo(outputStream* st, void* siginfo) {
   const siginfo_t* si = (const siginfo_t*)siginfo;
   os::Posix::print_siginfo_brief(st, si);
   if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
       UseSharedSpaces) {
     FileMapInfo* mapinfo = FileMapInfo::current_info();
     if (mapinfo->is_in_shared_space(si->si_addr)) {
       st->print("\n\nError accessing class data sharing archive."   \
                 " Mapped file inaccessible during execution, "      \
                 " possible disk/network problem.");
     }
   }
   st->cr();
 }
 static void print_signal_handler(outputStream* st, int sig,
                                  char* buf, size_t buflen);
 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
   st->print_cr("Signal Handlers:");
   print_signal_handler(st, SIGSEGV, buf, buflen);
   print_signal_handler(st, SIGBUS , buf, buflen);
   print_signal_handler(st, SIGFPE , buf, buflen);
   print_signal_handler(st, SIGPIPE, buf, buflen);
   print_signal_handler(st, SIGXFSZ, buf, buflen);
   print_signal_handler(st, SIGILL , buf, buflen);
   print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
   print_signal_handler(st, SR_signum, buf, buflen);
   print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
   print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
   print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
   print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
 }
 static char saved_jvm_path[MAXPATHLEN] = {0};
 // Find the full path to the current module, libjvm
 void os::jvm_path(char *buf, jint buflen) {
   // Error checking.
   if (buflen < MAXPATHLEN) {
     assert(false, "must use a large-enough buffer");
     buf[0] = '\0';
     return;
   }
   // Lazy resolve the path to current module.
   if (saved_jvm_path[0] != 0) {
     strcpy(buf, saved_jvm_path);
     return;
   }
   char dli_fname[MAXPATHLEN];
   bool ret = dll_address_to_library_name(
                 CAST_FROM_FN_PTR(address, os::jvm_path),
                 dli_fname, sizeof(dli_fname), NULL);
   assert(ret, "cannot locate libjvm");
   char *rp = NULL;
   if (ret && dli_fname[0] != '\0') {
     rp = realpath(dli_fname, buf);
   }
   if (rp == NULL)
     return;
   if (Arguments::created_by_gamma_launcher()) {
     // Support for the gamma launcher.  Typical value for buf is
     // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm".  If "/jre/lib/" appears at
     // the right place in the string, then assume we are installed in a JDK and
     // we're done.  Otherwise, check for a JAVA_HOME environment variable and
     // construct a path to the JVM being overridden.
     const char *p = buf + strlen(buf) - 1;
     for (int count = 0; p > buf && count < 5; ++count) {
       for (--p; p > buf && *p != '/'; --p)
         /* empty */ ;
     }
     if (strncmp(p, "/jre/lib/", 9) != 0) {
       // Look for JAVA_HOME in the environment.
       char* java_home_var = ::getenv("JAVA_HOME");
       if (java_home_var != NULL && java_home_var[0] != 0) {
         char* jrelib_p;
         int len;
         // Check the current module name "libjvm"
         p = strrchr(buf, '/');
         assert(strstr(p, "/libjvm") == p, "invalid library name");
         rp = realpath(java_home_var, buf);
         if (rp == NULL)
           return;
         // determine if this is a legacy image or modules image
         // modules image doesn't have "jre" subdirectory
         len = strlen(buf);
         assert(len < buflen, "Ran out of buffer space");
         jrelib_p = buf + len;
         // Add the appropriate library subdir
         snprintf(jrelib_p, buflen-len, "/jre/lib");
         if (0 != access(buf, F_OK)) {
           snprintf(jrelib_p, buflen-len, "/lib");
         }
         // Add the appropriate client or server subdir
         len = strlen(buf);
         jrelib_p = buf + len;
         snprintf(jrelib_p, buflen-len, "/%s", COMPILER_VARIANT);
         if (0 != access(buf, F_OK)) {
           snprintf(jrelib_p, buflen-len, "");
         }
         // If the path exists within JAVA_HOME, add the JVM library name
         // to complete the path to JVM being overridden.  Otherwise fallback
         // to the path to the current library.
         if (0 == access(buf, F_OK)) {
           // Use current module name "libjvm"
           len = strlen(buf);
           snprintf(buf + len, buflen-len, "/libjvm%s", JNI_LIB_SUFFIX);
         } else {
           // Fall back to path of current library
           rp = realpath(dli_fname, buf);
           if (rp == NULL)
             return;
         }
       }
     }
   }
   strncpy(saved_jvm_path, buf, MAXPATHLEN);
 }
 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
   // no prefix required, not even "_"
 }
 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
   // no suffix required
 }
 ////////////////////////////////////////////////////////////////////////////////
 // sun.misc.Signal support
 static volatile jint sigint_count = 0;
 static void
 UserHandler(int sig, void *siginfo, void *context) {
   // 4511530 - sem_post is serialized and handled by the manager thread. When
   // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
   // don't want to flood the manager thread with sem_post requests.
   if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
       return;
   // Ctrl-C is pressed during error reporting, likely because the error
   // handler fails to abort. Let VM die immediately.
   if (sig == SIGINT && is_error_reported()) {
      os::die();
   }
   os::signal_notify(sig);
 }
 void* os::user_handler() {
   return CAST_FROM_FN_PTR(void*, UserHandler);
 }
 extern "C" {
   typedef void (*sa_handler_t)(int);
   typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
 }
 void* os::signal(int signal_number, void* handler) {
   struct sigaction sigAct, oldSigAct;
   sigfillset(&(sigAct.sa_mask));
   sigAct.sa_flags   = SA_RESTART|SA_SIGINFO;
   sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
   if (sigaction(signal_number, &sigAct, &oldSigAct)) {
     // -1 means registration failed
     return (void *)-1;
   }
   return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
 }
 void os::signal_raise(int signal_number) {
   ::raise(signal_number);
 }
 /*
  * The following code is moved from os.cpp for making this
  * code platform specific, which it is by its very nature.
  */
 // Will be modified when max signal is changed to be dynamic
 int os::sigexitnum_pd() {
   return NSIG;
 }
 // a counter for each possible signal value
 static volatile jint pending_signals[NSIG+1] = { 0 };
 // Bsd(POSIX) specific hand shaking semaphore.
 #ifdef __APPLE__
 typedef semaphore_t os_semaphore_t;
 #define SEM_INIT(sem, value)    semaphore_create(mach_task_self(), &sem, SYNC_POLICY_FIFO, value)
 #define SEM_WAIT(sem)           semaphore_wait(sem)
 #define SEM_POST(sem)           semaphore_signal(sem)
 #define SEM_DESTROY(sem)        semaphore_destroy(mach_task_self(), sem)
 #else
 typedef sem_t os_semaphore_t;
 #define SEM_INIT(sem, value)    sem_init(&sem, 0, value)
 #define SEM_WAIT(sem)           sem_wait(&sem)
 #define SEM_POST(sem)           sem_post(&sem)
 #define SEM_DESTROY(sem)        sem_destroy(&sem)
 #endif
 class Semaphore : public StackObj {
   public:
     Semaphore();
     ~Semaphore();
     void signal();
     void wait();
     bool trywait();
     bool timedwait(unsigned int sec, int nsec);
   private:
     jlong currenttime() const;
     os_semaphore_t _semaphore;
 };
 Semaphore::Semaphore() : _semaphore(0) {
   SEM_INIT(_semaphore, 0);
 }
 Semaphore::~Semaphore() {
   SEM_DESTROY(_semaphore);
 }
 void Semaphore::signal() {
   SEM_POST(_semaphore);
 }
 void Semaphore::wait() {
   SEM_WAIT(_semaphore);
 }
 jlong Semaphore::currenttime() const {
     struct timeval tv;
     gettimeofday(&tv, NULL);
     return (tv.tv_sec * NANOSECS_PER_SEC) + (tv.tv_usec * 1000);
 }
 #ifdef __APPLE__
 bool Semaphore::trywait() {
   return timedwait(0, 0);
 }
 bool Semaphore::timedwait(unsigned int sec, int nsec) {
   kern_return_t kr = KERN_ABORTED;
   mach_timespec_t waitspec;
   waitspec.tv_sec = sec;
   waitspec.tv_nsec = nsec;
   jlong starttime = currenttime();
   kr = semaphore_timedwait(_semaphore, waitspec);
   while (kr == KERN_ABORTED) {
     jlong totalwait = (sec * NANOSECS_PER_SEC) + nsec;
     jlong current = currenttime();
     jlong passedtime = current - starttime;
     if (passedtime >= totalwait) {
       waitspec.tv_sec = 0;
       waitspec.tv_nsec = 0;
     } else {
       jlong waittime = totalwait - (current - starttime);
       waitspec.tv_sec = waittime / NANOSECS_PER_SEC;
       waitspec.tv_nsec = waittime % NANOSECS_PER_SEC;
     }
     kr = semaphore_timedwait(_semaphore, waitspec);
   }
   return kr == KERN_SUCCESS;
 }
 #else
 bool Semaphore::trywait() {
   return sem_trywait(&_semaphore) == 0;
 }
 bool Semaphore::timedwait(unsigned int sec, int nsec) {
   struct timespec ts;
   unpackTime(&ts, false, (sec * NANOSECS_PER_SEC) + nsec);
   while (1) {
     int result = sem_timedwait(&_semaphore, &ts);
     if (result == 0) {
       return true;
     } else if (errno == EINTR) {
       continue;
     } else if (errno == ETIMEDOUT) {
       return false;
     } else {
       return false;
     }
   }
 }
 #endif // __APPLE__
 static os_semaphore_t sig_sem;
 static Semaphore sr_semaphore;
 void os::signal_init_pd() {
   // Initialize signal structures
   ::memset((void*)pending_signals, 0, sizeof(pending_signals));
   // Initialize signal semaphore
   ::SEM_INIT(sig_sem, 0);
 }
 void os::signal_notify(int sig) {
   Atomic::inc(&pending_signals[sig]);
   ::SEM_POST(sig_sem);
 }
 static int check_pending_signals(bool wait) {
   Atomic::store(0, &sigint_count);
   for (;;) {
     for (int i = 0; i < NSIG + 1; i++) {
       jint n = pending_signals[i];
       if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
         return i;
       }
     }
     if (!wait) {
       return -1;
     }
     JavaThread *thread = JavaThread::current();
     ThreadBlockInVM tbivm(thread);
     bool threadIsSuspended;
     do {
       thread->set_suspend_equivalent();
       // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
       ::SEM_WAIT(sig_sem);
       // were we externally suspended while we were waiting?
       threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
       if (threadIsSuspended) {
         //
         // The semaphore has been incremented, but while we were waiting
         // another thread suspended us. We don't want to continue running
         // while suspended because that would surprise the thread that
         // suspended us.
         //
         ::SEM_POST(sig_sem);
         thread->java_suspend_self();
       }
     } while (threadIsSuspended);
   }
 }
 int os::signal_lookup() {
   return check_pending_signals(false);
 }
 int os::signal_wait() {
   return check_pending_signals(true);
 }
 ////////////////////////////////////////////////////////////////////////////////
 // Virtual Memory
 int os::vm_page_size() {
   // Seems redundant as all get out
   assert(os::Bsd::page_size() != -1, "must call os::init");
   return os::Bsd::page_size();
 }
 // Solaris allocates memory by pages.
 int os::vm_allocation_granularity() {
   assert(os::Bsd::page_size() != -1, "must call os::init");
   return os::Bsd::page_size();
 }
 // Rationale behind this function:
 //  current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
 //  mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
 //  samples for JITted code. Here we create private executable mapping over the code cache
 //  and then we can use standard (well, almost, as mapping can change) way to provide
 //  info for the reporting script by storing timestamp and location of symbol
 void bsd_wrap_code(char* base, size_t size) {
   static volatile jint cnt = 0;
   if (!UseOprofile) {
     return;
   }
   char buf[PATH_MAX + 1];
   int num = Atomic::add(1, &cnt);
   snprintf(buf, PATH_MAX + 1, "%s/hs-vm-%d-%d",
            os::get_temp_directory(), os::current_process_id(), num);
   unlink(buf);
   int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
   if (fd != -1) {
     off_t rv = ::lseek(fd, size-2, SEEK_SET);
     if (rv != (off_t)-1) {
       if (::write(fd, "", 1) == 1) {
         mmap(base, size,
              PROT_READ|PROT_WRITE|PROT_EXEC,
              MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
       }
     }
     ::close(fd);
     unlink(buf);
   }
 }
 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
                                     int err) {
   warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
           ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
           strerror(err), err);
 }
 // NOTE: Bsd kernel does not really reserve the pages for us.
 //       All it does is to check if there are enough free pages
 //       left at the time of mmap(). This could be a potential
 //       problem.
 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
   int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
 #ifdef __OpenBSD__
   // XXX: Work-around mmap/MAP_FIXED bug temporarily on OpenBSD
   if (::mprotect(addr, size, prot) == 0) {
     return true;
   }
 #else
   uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
                                    MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
   if (res != (uintptr_t) MAP_FAILED) {
     return true;
   }
 #endif
   // Warn about any commit errors we see in non-product builds just
   // in case mmap() doesn't work as described on the man page.
   NOT_PRODUCT(warn_fail_commit_memory(addr, size, exec, errno);)
   return false;
 }
 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
                        bool exec) {
   // alignment_hint is ignored on this OS
   return pd_commit_memory(addr, size, exec);
 }
 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
                                   const char* mesg) {
   assert(mesg != NULL, "mesg must be specified");
   if (!pd_commit_memory(addr, size, exec)) {
     // add extra info in product mode for vm_exit_out_of_memory():
     PRODUCT_ONLY(warn_fail_commit_memory(addr, size, exec, errno);)
     vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
   }
 }
 void os::pd_commit_memory_or_exit(char* addr, size_t size,
                                   size_t alignment_hint, bool exec,
                                   const char* mesg) {
   // alignment_hint is ignored on this OS
   pd_commit_memory_or_exit(addr, size, exec, mesg);
 }
 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
 }
 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
   ::madvise(addr, bytes, MADV_DONTNEED);
 }
 void os::numa_make_global(char *addr, size_t bytes) {
 }
 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
 }
 bool os::numa_topology_changed()   { return false; }
 size_t os::numa_get_groups_num() {
   return 1;
 }
 int os::numa_get_group_id() {
   return 0;
 }
 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
   if (size > 0) {
     ids[0] = 0;
     return 1;
   }
   return 0;
 }
 bool os::get_page_info(char *start, page_info* info) {
   return false;
 }
 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
   return end;
 }
 bool os::pd_uncommit_memory(char* addr, size_t size) {
 #ifdef __OpenBSD__
   // XXX: Work-around mmap/MAP_FIXED bug temporarily on OpenBSD
   return ::mprotect(addr, size, PROT_NONE) == 0;
 #else
   uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
                 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
   return res  != (uintptr_t) MAP_FAILED;
 #endif
 }
 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
   return os::commit_memory(addr, size, !ExecMem);
 }
 // If this is a growable mapping, remove the guard pages entirely by
 // munmap()ping them.  If not, just call uncommit_memory().
 bool os::remove_stack_guard_pages(char* addr, size_t size) {
   return os::uncommit_memory(addr, size);
 }
 static address _highest_vm_reserved_address = NULL;
 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
 // at 'requested_addr'. If there are existing memory mappings at the same
 // location, however, they will be overwritten. If 'fixed' is false,
 // 'requested_addr' is only treated as a hint, the return value may or
 // may not start from the requested address. Unlike Bsd mmap(), this
 // function returns NULL to indicate failure.
 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
   char * addr;
   int flags;
   flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
   if (fixed) {
     assert((uintptr_t)requested_addr % os::Bsd::page_size() == 0, "unaligned address");
     flags |= MAP_FIXED;
   }
   // Map reserved/uncommitted pages PROT_NONE so we fail early if we
   // touch an uncommitted page. Otherwise, the read/write might
   // succeed if we have enough swap space to back the physical page.
   addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
                        flags, -1, 0);
   if (addr != MAP_FAILED) {
     // anon_mmap() should only get called during VM initialization,
     // don't need lock (actually we can skip locking even it can be called
     // from multiple threads, because _highest_vm_reserved_address is just a
     // hint about the upper limit of non-stack memory regions.)
     if ((address)addr + bytes > _highest_vm_reserved_address) {
       _highest_vm_reserved_address = (address)addr + bytes;
     }
   }
   return addr == MAP_FAILED ? NULL : addr;
 }
 // Don't update _highest_vm_reserved_address, because there might be memory
 // regions above addr + size. If so, releasing a memory region only creates
 // a hole in the address space, it doesn't help prevent heap-stack collision.
 //
 static int anon_munmap(char * addr, size_t size) {
   return ::munmap(addr, size) == 0;
 }
 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
                          size_t alignment_hint) {
   return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
 }
 bool os::pd_release_memory(char* addr, size_t size) {
   return anon_munmap(addr, size);
 }
 static bool bsd_mprotect(char* addr, size_t size, int prot) {
   // Bsd wants the mprotect address argument to be page aligned.
   char* bottom = (char*)align_size_down((intptr_t)addr, os::Bsd::page_size());
   // According to SUSv3, mprotect() should only be used with mappings
   // established by mmap(), and mmap() always maps whole pages. Unaligned
   // 'addr' likely indicates problem in the VM (e.g. trying to change
   // protection of malloc'ed or statically allocated memory). Check the
   // caller if you hit this assert.
   assert(addr == bottom, "sanity check");
   size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Bsd::page_size());
   return ::mprotect(bottom, size, prot) == 0;
 }
 // Set protections specified
 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
                         bool is_committed) {
   unsigned int p = 0;
   switch (prot) {
   case MEM_PROT_NONE: p = PROT_NONE; break;
   case MEM_PROT_READ: p = PROT_READ; break;
   case MEM_PROT_RW:   p = PROT_READ|PROT_WRITE; break;
   case MEM_PROT_RWX:  p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
   default:
     ShouldNotReachHere();
   }
   // is_committed is unused.
   return bsd_mprotect(addr, bytes, p);
 }
 bool os::guard_memory(char* addr, size_t size) {
   return bsd_mprotect(addr, size, PROT_NONE);
 }
 bool os::unguard_memory(char* addr, size_t size) {
   return bsd_mprotect(addr, size, PROT_READ|PROT_WRITE);
 }
 bool os::Bsd::hugetlbfs_sanity_check(bool warn, size_t page_size) {
   return false;
 }
 // Large page support
 static size_t _large_page_size = 0;
 void os::large_page_init() {
 }
 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) {
   fatal("This code is not used or maintained.");
   // "exec" is passed in but not used.  Creating the shared image for
   // the code cache doesn't have an SHM_X executable permission to check.
   assert(UseLargePages && UseSHM, "only for SHM large pages");
   key_t key = IPC_PRIVATE;
   char *addr;
   bool warn_on_failure = UseLargePages &&
                         (!FLAG_IS_DEFAULT(UseLargePages) ||
                          !FLAG_IS_DEFAULT(LargePageSizeInBytes)
                         );
   // Create a large shared memory region to attach to based on size.
   // Currently, size is the total size of the heap
   int shmid = shmget(key, bytes, IPC_CREAT|SHM_R|SHM_W);
   if (shmid == -1) {
      // Possible reasons for shmget failure:
      // 1. shmmax is too small for Java heap.
      //    > check shmmax value: cat /proc/sys/kernel/shmmax
      //    > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
      // 2. not enough large page memory.
      //    > check available large pages: cat /proc/meminfo
      //    > increase amount of large pages:
      //          echo new_value > /proc/sys/vm/nr_hugepages
      //      Note 1: different Bsd may use different name for this property,
      //            e.g. on Redhat AS-3 it is "hugetlb_pool".
      //      Note 2: it's possible there's enough physical memory available but
      //            they are so fragmented after a long run that they can't
      //            coalesce into large pages. Try to reserve large pages when
      //            the system is still "fresh".
      if (warn_on_failure) {
        warning("Failed to reserve shared memory (errno = %d).", errno);
      }
      return NULL;
   }
   // attach to the region
   addr = (char*)shmat(shmid, req_addr, 0);
   int err = errno;
   // Remove shmid. If shmat() is successful, the actual shared memory segment
   // will be deleted when it's detached by shmdt() or when the process
   // terminates. If shmat() is not successful this will remove the shared
   // segment immediately.
   shmctl(shmid, IPC_RMID, NULL);
   if ((intptr_t)addr == -1) {
      if (warn_on_failure) {
        warning("Failed to attach shared memory (errno = %d).", err);
      }
      return NULL;
   }
   // The memory is committed
   MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
   return addr;
 }
 bool os::release_memory_special(char* base, size_t bytes) {
   if (MemTracker::tracking_level() > NMT_minimal) {
     Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
     // detaching the SHM segment will also delete it, see reserve_memory_special()
     int rslt = shmdt(base);
     if (rslt == 0) {
       tkr.record((address)base, bytes);
       return true;
     } else {
       return false;
     }
   } else {
     return shmdt(base) == 0;
   }
 }
 size_t os::large_page_size() {
   return _large_page_size;
 }
 // HugeTLBFS allows application to commit large page memory on demand;
 // with SysV SHM the entire memory region must be allocated as shared
 // memory.
 bool os::can_commit_large_page_memory() {
   return UseHugeTLBFS;
 }
 bool os::can_execute_large_page_memory() {
   return UseHugeTLBFS;
 }
 // Reserve memory at an arbitrary address, only if that area is
 // available (and not reserved for something else).
 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
   const int max_tries = 10;
   char* base[max_tries];
   size_t size[max_tries];
   const size_t gap = 0x000000;
   // Assert only that the size is a multiple of the page size, since
   // that's all that mmap requires, and since that's all we really know
   // about at this low abstraction level.  If we need higher alignment,
   // we can either pass an alignment to this method or verify alignment
   // in one of the methods further up the call chain.  See bug 5044738.
   assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
   // Repeatedly allocate blocks until the block is allocated at the
   // right spot. Give up after max_tries. Note that reserve_memory() will
   // automatically update _highest_vm_reserved_address if the call is
   // successful. The variable tracks the highest memory address every reserved
   // by JVM. It is used to detect heap-stack collision if running with
   // fixed-stack BsdThreads. Because here we may attempt to reserve more
   // space than needed, it could confuse the collision detecting code. To
   // solve the problem, save current _highest_vm_reserved_address and
   // calculate the correct value before return.
   address old_highest = _highest_vm_reserved_address;
   // Bsd mmap allows caller to pass an address as hint; give it a try first,
   // if kernel honors the hint then we can return immediately.
   char * addr = anon_mmap(requested_addr, bytes, false);
   if (addr == requested_addr) {
      return requested_addr;
   }
   if (addr != NULL) {
      // mmap() is successful but it fails to reserve at the requested address
      anon_munmap(addr, bytes);
   }
   int i;
   for (i = 0; i < max_tries; ++i) {
     base[i] = reserve_memory(bytes);
     if (base[i] != NULL) {
       // Is this the block we wanted?
       if (base[i] == requested_addr) {
         size[i] = bytes;
         break;
       }
       // Does this overlap the block we wanted? Give back the overlapped
       // parts and try again.
       size_t top_overlap = requested_addr + (bytes + gap) - base[i];
       if (top_overlap >= 0 && top_overlap < bytes) {
         unmap_memory(base[i], top_overlap);
         base[i] += top_overlap;
         size[i] = bytes - top_overlap;
       } else {
         size_t bottom_overlap = base[i] + bytes - requested_addr;
         if (bottom_overlap >= 0 && bottom_overlap < bytes) {
           unmap_memory(requested_addr, bottom_overlap);
           size[i] = bytes - bottom_overlap;
         } else {
           size[i] = bytes;
         }
       }
     }
   }
   // Give back the unused reserved pieces.
   for (int j = 0; j < i; ++j) {
     if (base[j] != NULL) {
       unmap_memory(base[j], size[j]);
     }
   }
   if (i < max_tries) {
     _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
     return requested_addr;
   } else {
     _highest_vm_reserved_address = old_highest;
     return NULL;
   }
 }
 size_t os::read(int fd, void *buf, unsigned int nBytes) {
   RESTARTABLE_RETURN_INT(::read(fd, buf, nBytes));
 }
 // TODO-FIXME: reconcile Solaris' os::sleep with the bsd variation.
 // Solaris uses poll(), bsd uses park().
 // Poll() is likely a better choice, assuming that Thread.interrupt()
 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with
 // SIGSEGV, see 4355769.
 int os::sleep(Thread* thread, jlong millis, bool interruptible) {
   assert(thread == Thread::current(),  "thread consistency check");
   ParkEvent * const slp = thread->_SleepEvent ;
   slp->reset() ;
   OrderAccess::fence() ;
   if (interruptible) {
     jlong prevtime = javaTimeNanos();
     for (;;) {
       if (os::is_interrupted(thread, true)) {
         return OS_INTRPT;
       }
       jlong newtime = javaTimeNanos();
       if (newtime - prevtime < 0) {
         // time moving backwards, should only happen if no monotonic clock
         // not a guarantee() because JVM should not abort on kernel/glibc bugs
         assert(!Bsd::supports_monotonic_clock(), "time moving backwards");
       } else {
         millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
       }
       if(millis <= 0) {
         return OS_OK;
       }
       prevtime = newtime;
       {
         assert(thread->is_Java_thread(), "sanity check");
         JavaThread *jt = (JavaThread *) thread;
         ThreadBlockInVM tbivm(jt);
         OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
         jt->set_suspend_equivalent();
         // cleared by handle_special_suspend_equivalent_condition() or
         // java_suspend_self() via check_and_wait_while_suspended()
         slp->park(millis);
         // were we externally suspended while we were waiting?
         jt->check_and_wait_while_suspended();
       }
     }
   } else {
     OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
     jlong prevtime = javaTimeNanos();
     for (;;) {
       // It'd be nice to avoid the back-to-back javaTimeNanos() calls on
       // the 1st iteration ...
       jlong newtime = javaTimeNanos();
       if (newtime - prevtime < 0) {
         // time moving backwards, should only happen if no monotonic clock
         // not a guarantee() because JVM should not abort on kernel/glibc bugs
         assert(!Bsd::supports_monotonic_clock(), "time moving backwards");
       } else {
         millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
       }
       if(millis <= 0) break ;
       prevtime = newtime;
       slp->park(millis);
     }
     return OS_OK ;
   }
 }
 void os::naked_short_sleep(jlong ms) {
   struct timespec req;
   assert(ms < 1000, "Un-interruptable sleep, short time use only");
   req.tv_sec = 0;
   if (ms > 0) {
     req.tv_nsec = (ms % 1000) * 1000000;
   }
   else {
     req.tv_nsec = 1;
   }
   nanosleep(&req, NULL);
   return;
 }
 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
 void os::infinite_sleep() {
   while (true) {    // sleep forever ...
     ::sleep(100);   // ... 100 seconds at a time
   }
 }
 // Used to convert frequent JVM_Yield() to nops
 bool os::dont_yield() {
   return DontYieldALot;
 }
 void os::yield() {
   sched_yield();
 }
 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
 void os::yield_all(int attempts) {
   // Yields to all threads, including threads with lower priorities
   // Threads on Bsd are all with same priority. The Solaris style
   // os::yield_all() with nanosleep(1ms) is not necessary.
   sched_yield();
 }
 // Called from the tight loops to possibly influence time-sharing heuristics
 void os::loop_breaker(int attempts) {
   os::yield_all(attempts);
 }
 ////////////////////////////////////////////////////////////////////////////////
 // thread priority support
 // Note: Normal Bsd applications are run with SCHED_OTHER policy. SCHED_OTHER
 // only supports dynamic priority, static priority must be zero. For real-time
 // applications, Bsd supports SCHED_RR which allows static priority (1-99).
 // However, for large multi-threaded applications, SCHED_RR is not only slower
 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
 // of 5 runs - Sep 2005).
 //
 // The following code actually changes the niceness of kernel-thread/LWP. It
 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
 // not the entire user process, and user level threads are 1:1 mapped to kernel
 // threads. It has always been the case, but could change in the future. For
 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
 #if !defined(__APPLE__)
 int os::java_to_os_priority[CriticalPriority + 1] = {
 ,              // 0 Entry should never be used
 ,              // 1 MinPriority
 ,              // 2
 ,              // 3
 ,              // 4
 ,              // 5 NormPriority
 ,              // 6
 ,              // 7
 ,              // 8
 ,              // 9 NearMaxPriority
 ,              // 10 MaxPriority
 // 11 CriticalPriority
 };
 #else
 /* Using Mach high-level priority assignments */
 int os::java_to_os_priority[CriticalPriority + 1] = {
 ,              // 0 Entry should never be used (MINPRI_USER)
 ,              // 1 MinPriority
 ,              // 2
 ,              // 3
 ,              // 4
 ,              // 5 NormPriority (BASEPRI_DEFAULT)
 ,              // 6
 ,              // 7
 ,              // 8
 ,              // 9 NearMaxPriority
 ,              // 10 MaxPriority
 // 11 CriticalPriority
 };
 #endif
 static int prio_init() {
   if (ThreadPriorityPolicy == 1) {
     // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
     // if effective uid is not root. Perhaps, a more elegant way of doing
     // this is to test CAP_SYS_NICE capability, but that will require libcap.so
     if (geteuid() != 0) {
       if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
         warning("-XX:ThreadPriorityPolicy requires root privilege on Bsd");
       }
       ThreadPriorityPolicy = 0;
     }
   }
   if (UseCriticalJavaThreadPriority) {
     os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
   }
   return 0;
 }
 OSReturn os::set_native_priority(Thread* thread, int newpri) {
   if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
 #ifdef __OpenBSD__
   // OpenBSD pthread_setprio starves low priority threads
   return OS_OK;
 #elif defined(__FreeBSD__)
   int ret = pthread_setprio(thread->osthread()->pthread_id(), newpri);
 #elif defined(__APPLE__) || defined(__NetBSD__)
   struct sched_param sp;
   int policy;
   pthread_t self = pthread_self();
   if (pthread_getschedparam(self, &policy, &sp) != 0)
     return OS_ERR;
   sp.sched_priority = newpri;
   if (pthread_setschedparam(self, policy, &sp) != 0)
     return OS_ERR;
   return OS_OK;
 #else
   int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
   return (ret == 0) ? OS_OK : OS_ERR;
 #endif
 }
 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
   if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
     *priority_ptr = java_to_os_priority[NormPriority];
     return OS_OK;
   }
   errno = 0;
 #if defined(__OpenBSD__) || defined(__FreeBSD__)
   *priority_ptr = pthread_getprio(thread->osthread()->pthread_id());
 #elif defined(__APPLE__) || defined(__NetBSD__)
   int policy;
   struct sched_param sp;
   pthread_getschedparam(pthread_self(), &policy, &sp);
   *priority_ptr = sp.sched_priority;
 #else
   *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
 #endif
   return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
 }
 // Hint to the underlying OS that a task switch would not be good.
 // Void return because it's a hint and can fail.
 void os::hint_no_preempt() {}
 ////////////////////////////////////////////////////////////////////////////////
 // suspend/resume support
 //  the low-level signal-based suspend/resume support is a remnant from the
 //  old VM-suspension that used to be for java-suspension, safepoints etc,
 //  within hotspot. Now there is a single use-case for this:
 //    - calling get_thread_pc() on the VMThread by the flat-profiler task
 //      that runs in the watcher thread.
 //  The remaining code is greatly simplified from the more general suspension
 //  code that used to be used.
 //
 //  The protocol is quite simple:
 //  - suspend:
 //      - sends a signal to the target thread
 //      - polls the suspend state of the osthread using a yield loop
 //      - target thread signal handler (SR_handler) sets suspend state
 //        and blocks in sigsuspend until continued
 //  - resume:
 //      - sets target osthread state to continue
 //      - sends signal to end the sigsuspend loop in the SR_handler
 //
 //  Note that the SR_lock plays no role in this suspend/resume protocol.
 //
 static void resume_clear_context(OSThread *osthread) {
   osthread->set_ucontext(NULL);
   osthread->set_siginfo(NULL);
 }
 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
   osthread->set_ucontext(context);
   osthread->set_siginfo(siginfo);
 }
 //
 // Handler function invoked when a thread's execution is suspended or
 // resumed. We have to be careful that only async-safe functions are
 // called here (Note: most pthread functions are not async safe and
 // should be avoided.)
 //
 // Note: sigwait() is a more natural fit than sigsuspend() from an
 // interface point of view, but sigwait() prevents the signal hander
 // from being run. libpthread would get very confused by not having
 // its signal handlers run and prevents sigwait()'s use with the
 // mutex granting granting signal.
 //
 // Currently only ever called on the VMThread or JavaThread
 //
 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
   // Save and restore errno to avoid confusing native code with EINTR
   // after sigsuspend.
   int old_errno = errno;
   Thread* thread = Thread::current();
   OSThread* osthread = thread->osthread();
   assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
   os::SuspendResume::State current = osthread->sr.state();
   if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
     suspend_save_context(osthread, siginfo, context);
     // attempt to switch the state, we assume we had a SUSPEND_REQUEST
     os::SuspendResume::State state = osthread->sr.suspended();
     if (state == os::SuspendResume::SR_SUSPENDED) {
       sigset_t suspend_set;  // signals for sigsuspend()
       // get current set of blocked signals and unblock resume signal
       pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
       sigdelset(&suspend_set, SR_signum);
       sr_semaphore.signal();
       // wait here until we are resumed
       while (1) {
         sigsuspend(&suspend_set);
         os::SuspendResume::State result = osthread->sr.running();
         if (result == os::SuspendResume::SR_RUNNING) {
           sr_semaphore.signal();
           break;
         } else if (result != os::SuspendResume::SR_SUSPENDED) {
           ShouldNotReachHere();
         }
       }
     } else if (state == os::SuspendResume::SR_RUNNING) {
       // request was cancelled, continue
     } else {
       ShouldNotReachHere();
     }
     resume_clear_context(osthread);
   } else if (current == os::SuspendResume::SR_RUNNING) {
     // request was cancelled, continue
   } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
     // ignore
   } else {
     // ignore
   }
   errno = old_errno;
 }
 static int SR_initialize() {
   struct sigaction act;
   char *s;
   /* Get signal number to use for suspend/resume */
   if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
     int sig = ::strtol(s, 0, 10);
     if (sig > 0 || sig < NSIG) {
         SR_signum = sig;
     }
   }
   assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
         "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
   sigemptyset(&SR_sigset);
   sigaddset(&SR_sigset, SR_signum);
   /* Set up signal handler for suspend/resume */
   act.sa_flags = SA_RESTART|SA_SIGINFO;
   act.sa_handler = (void (*)(int)) SR_handler;
   // SR_signum is blocked by default.
   // 4528190 - We also need to block pthread restart signal (32 on all
   // supported Bsd platforms). Note that BsdThreads need to block
   // this signal for all threads to work properly. So we don't have
   // to use hard-coded signal number when setting up the mask.
   pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
   if (sigaction(SR_signum, &act, 0) == -1) {
     return -1;
   }
   // Save signal flag
   os::Bsd::set_our_sigflags(SR_signum, act.sa_flags);
   return 0;
 }
 static int sr_notify(OSThread* osthread) {
   int status = pthread_kill(osthread->pthread_id(), SR_signum);
   assert_status(status == 0, status, "pthread_kill");
   return status;
 }
 // "Randomly" selected value for how long we want to spin
 // before bailing out on suspending a thread, also how often
 // we send a signal to a thread we want to resume
 static const int RANDOMLY_LARGE_INTEGER = 1000000;
 static const int RANDOMLY_LARGE_INTEGER2 = 100;
 // returns true on success and false on error - really an error is fatal
 // but this seems the normal response to library errors
 static bool do_suspend(OSThread* osthread) {
   assert(osthread->sr.is_running(), "thread should be running");
   assert(!sr_semaphore.trywait(), "semaphore has invalid state");
   // mark as suspended and send signal
   if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
     // failed to switch, state wasn't running?
     ShouldNotReachHere();
     return false;
   }
   if (sr_notify(osthread) != 0) {
     ShouldNotReachHere();
   }
   // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
   while (true) {
     if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
       break;
     } else {
       // timeout
       os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
       if (cancelled == os::SuspendResume::SR_RUNNING) {
         return false;
       } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
         // make sure that we consume the signal on the semaphore as well
         sr_semaphore.wait();
         break;
       } else {
         ShouldNotReachHere();
         return false;
       }
     }
   }
   guarantee(osthread->sr.is_suspended(), "Must be suspended");
   return true;
 }
 static void do_resume(OSThread* osthread) {
   assert(osthread->sr.is_suspended(), "thread should be suspended");
   assert(!sr_semaphore.trywait(), "invalid semaphore state");
   if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
     // failed to switch to WAKEUP_REQUEST
     ShouldNotReachHere();
     return;
   }
   while (true) {
     if (sr_notify(osthread) == 0) {
       if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
         if (osthread->sr.is_running()) {
           return;
         }
       }
     } else {
       ShouldNotReachHere();
     }
   }
   guarantee(osthread->sr.is_running(), "Must be running!");
 }
 ////////////////////////////////////////////////////////////////////////////////
 // interrupt support
 void os::interrupt(Thread* thread) {
   assert(Thread::current() == thread || Threads_lock->owned_by_self(),
     "possibility of dangling Thread pointer");
   OSThread* osthread = thread->osthread();
   if (!osthread->interrupted()) {
     osthread->set_interrupted(true);
     // More than one thread can get here with the same value of osthread,
     // resulting in multiple notifications.  We do, however, want the store
     // to interrupted() to be visible to other threads before we execute unpark().
     OrderAccess::fence();
     ParkEvent * const slp = thread->_SleepEvent ;
     if (slp != NULL) slp->unpark() ;
   }
   // For JSR166. Unpark even if interrupt status already was set
   if (thread->is_Java_thread())
     ((JavaThread*)thread)->parker()->unpark();
   ParkEvent * ev = thread->_ParkEvent ;
   if (ev != NULL) ev->unpark() ;
 }
 bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
   assert(Thread::current() == thread || Threads_lock->owned_by_self(),
     "possibility of dangling Thread pointer");
   OSThread* osthread = thread->osthread();
   bool interrupted = osthread->interrupted();
   if (interrupted && clear_interrupted) {
     osthread->set_interrupted(false);
     // consider thread->_SleepEvent->reset() ... optional optimization
   }
   return interrupted;
 }
 ///////////////////////////////////////////////////////////////////////////////////
 // signal handling (except suspend/resume)
 // This routine may be used by user applications as a "hook" to catch signals.
 // The user-defined signal handler must pass unrecognized signals to this
 // routine, and if it returns true (non-zero), then the signal handler must
 // return immediately.  If the flag "abort_if_unrecognized" is true, then this
 // routine will never retun false (zero), but instead will execute a VM panic
 // routine kill the process.
 //
 // If this routine returns false, it is OK to call it again.  This allows
 // the user-defined signal handler to perform checks either before or after
 // the VM performs its own checks.  Naturally, the user code would be making
 // a serious error if it tried to handle an exception (such as a null check
 // or breakpoint) that the VM was generating for its own correct operation.
 //
 // This routine may recognize any of the following kinds of signals:
 //    SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
 // It should be consulted by handlers for any of those signals.
 //
 // The caller of this routine must pass in the three arguments supplied
 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
 // field of the structure passed to sigaction().  This routine assumes that
 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
 //
 // Note that the VM will print warnings if it detects conflicting signal
 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
 //
 extern "C" JNIEXPORT int
 JVM_handle_bsd_signal(int signo, siginfo_t* siginfo,
                         void* ucontext, int abort_if_unrecognized);
 void signalHandler(int sig, siginfo_t* info, void* uc) {
   assert(info != NULL && uc != NULL, "it must be old kernel");
   int orig_errno = errno;  // Preserve errno value over signal handler.
   JVM_handle_bsd_signal(sig, info, uc, true);
   errno = orig_errno;
 }
 // This boolean allows users to forward their own non-matching signals
 // to JVM_handle_bsd_signal, harmlessly.
 bool os::Bsd::signal_handlers_are_installed = false;
 // For signal-chaining
 struct sigaction os::Bsd::sigact[MAXSIGNUM];
 unsigned int os::Bsd::sigs = 0;
 bool os::Bsd::libjsig_is_loaded = false;
 typedef struct sigaction *(*get_signal_t)(int);
 get_signal_t os::Bsd::get_signal_action = NULL;
 struct sigaction* os::Bsd::get_chained_signal_action(int sig) {
   struct sigaction *actp = NULL;
   if (libjsig_is_loaded) {
     // Retrieve the old signal handler from libjsig
     actp = (*get_signal_action)(sig);
   }
   if (actp == NULL) {
     // Retrieve the preinstalled signal handler from jvm
     actp = get_preinstalled_handler(sig);
   }
   return actp;
 }
 static bool call_chained_handler(struct sigaction *actp, int sig,
                                  siginfo_t *siginfo, void *context) {
   // Call the old signal handler
   if (actp->sa_handler == SIG_DFL) {
     // It's more reasonable to let jvm treat it as an unexpected exception
     // instead of taking the default action.
     return false;
   } else if (actp->sa_handler != SIG_IGN) {
     if ((actp->sa_flags & SA_NODEFER) == 0) {
       // automaticlly block the signal
       sigaddset(&(actp->sa_mask), sig);
     }
     sa_handler_t hand;
     sa_sigaction_t sa;
     bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
     // retrieve the chained handler
     if (siginfo_flag_set) {
       sa = actp->sa_sigaction;
     } else {
       hand = actp->sa_handler;
     }
     if ((actp->sa_flags & SA_RESETHAND) != 0) {
       actp->sa_handler = SIG_DFL;
     }
     // try to honor the signal mask
     sigset_t oset;
     pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
     // call into the chained handler
     if (siginfo_flag_set) {
       (*sa)(sig, siginfo, context);
     } else {
       (*hand)(sig);
     }
     // restore the signal mask
     pthread_sigmask(SIG_SETMASK, &oset, 0);
   }
   // Tell jvm's signal handler the signal is taken care of.
   return true;
 }
 bool os::Bsd::chained_handler(int sig, siginfo_t* siginfo, void* context) {
   bool chained = false;
   // signal-chaining
   if (UseSignalChaining) {
     struct sigaction *actp = get_chained_signal_action(sig);
     if (actp != NULL) {
       chained = call_chained_handler(actp, sig, siginfo, context);
     }
   }
   return chained;
 }
 struct sigaction* os::Bsd::get_preinstalled_handler(int sig) {
   if ((( (unsigned int)1 << sig ) & sigs) != 0) {
     return &sigact[sig];
   }
   return NULL;
 }
 void os::Bsd::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
   assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
   sigact[sig] = oldAct;
   sigs |= (unsigned int)1 << sig;
 }
 // for diagnostic
 int os::Bsd::sigflags[MAXSIGNUM];
 int os::Bsd::get_our_sigflags(int sig) {
   assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
   return sigflags[sig];
 }
 void os::Bsd::set_our_sigflags(int sig, int flags) {
   assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
   sigflags[sig] = flags;
 }
 void os::Bsd::set_signal_handler(int sig, bool set_installed) {
   // Check for overwrite.
   struct sigaction oldAct;
   sigaction(sig, (struct sigaction*)NULL, &oldAct);
   void* oldhand = oldAct.sa_sigaction
                 ? CAST_FROM_FN_PTR(void*,  oldAct.sa_sigaction)
                 : CAST_FROM_FN_PTR(void*,  oldAct.sa_handler);
   if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
       oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
       oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
     if (AllowUserSignalHandlers || !set_installed) {
       // Do not overwrite; user takes responsibility to forward to us.
       return;
     } else if (UseSignalChaining) {
       // save the old handler in jvm
       save_preinstalled_handler(sig, oldAct);
       // libjsig also interposes the sigaction() call below and saves the
       // old sigaction on it own.
     } else {
       fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
                     "%#lx for signal %d.", (long)oldhand, sig));
     }
   }
   struct sigaction sigAct;
   sigfillset(&(sigAct.sa_mask));
   sigAct.sa_handler = SIG_DFL;
   if (!set_installed) {
     sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
   } else {
     sigAct.sa_sigaction = signalHandler;
     sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
   }
 #ifdef __APPLE__
   // Needed for main thread as XNU (Mac OS X kernel) will only deliver SIGSEGV
   // (which starts as SIGBUS) on main thread with faulting address inside "stack+guard pages"
   // if the signal handler declares it will handle it on alternate stack.
   // Notice we only declare we will handle it on alt stack, but we are not
   // actually going to use real alt stack - this is just a workaround.
   // Please see ux_exception.c, method catch_mach_exception_raise for details
   // link http://www.opensource.apple.com/source/xnu/xnu-2050.18.24/bsd/uxkern/ux_exception.c
   if (sig == SIGSEGV) {
     sigAct.sa_flags |= SA_ONSTACK;
   }
 #endif
   // Save flags, which are set by ours
   assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
   sigflags[sig] = sigAct.sa_flags;
   int ret = sigaction(sig, &sigAct, &oldAct);
   assert(ret == 0, "check");
   void* oldhand2  = oldAct.sa_sigaction
                   ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
                   : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
   assert(oldhand2 == oldhand, "no concurrent signal handler installation");
 }
 // install signal handlers for signals that HotSpot needs to
 // handle in order to support Java-level exception handling.
 void os::Bsd::install_signal_handlers() {
   if (!signal_handlers_are_installed) {
     signal_handlers_are_installed = true;
     // signal-chaining
     typedef void (*signal_setting_t)();
     signal_setting_t begin_signal_setting = NULL;
     signal_setting_t end_signal_setting = NULL;
     begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
                              dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
     if (begin_signal_setting != NULL) {
       end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
                              dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
       get_signal_action = CAST_TO_FN_PTR(get_signal_t,
                             dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
       libjsig_is_loaded = true;
       assert(UseSignalChaining, "should enable signal-chaining");
     }
     if (libjsig_is_loaded) {
       // Tell libjsig jvm is setting signal handlers
       (*begin_signal_setting)();
     }
     set_signal_handler(SIGSEGV, true);
     set_signal_handler(SIGPIPE, true);
     set_signal_handler(SIGBUS, true);
     set_signal_handler(SIGILL, true);
     set_signal_handler(SIGFPE, true);
     set_signal_handler(SIGXFSZ, true);
 #if defined(__APPLE__)
     // In Mac OS X 10.4, CrashReporter will write a crash log for all 'fatal' signals, including
     // signals caught and handled by the JVM. To work around this, we reset the mach task
     // signal handler that's placed on our process by CrashReporter. This disables
     // CrashReporter-based reporting.
     //
     // This work-around is not necessary for 10.5+, as CrashReporter no longer intercedes
     // on caught fatal signals.
     //
     // Additionally, gdb installs both standard BSD signal handlers, and mach exception
     // handlers. By replacing the existing task exception handler, we disable gdb's mach
     // exception handling, while leaving the standard BSD signal handlers functional.
     kern_return_t kr;
     kr = task_set_exception_ports(mach_task_self(),
         EXC_MASK_BAD_ACCESS | EXC_MASK_ARITHMETIC,
         MACH_PORT_NULL,
         EXCEPTION_STATE_IDENTITY,
         MACHINE_THREAD_STATE);
     assert(kr == KERN_SUCCESS, "could not set mach task signal handler");
 #endif
     if (libjsig_is_loaded) {
       // Tell libjsig jvm finishes setting signal handlers
       (*end_signal_setting)();
     }
     // We don't activate signal checker if libjsig is in place, we trust ourselves
     // and if UserSignalHandler is installed all bets are off
     if (CheckJNICalls) {
       if (libjsig_is_loaded) {
         if (PrintJNIResolving) {
           tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
         }
         check_signals = false;
       }
       if (AllowUserSignalHandlers) {
         if (PrintJNIResolving) {
           tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
         }
         check_signals = false;
       }
     }
   }
 }
 /////
 // glibc on Bsd platform uses non-documented flag
 // to indicate, that some special sort of signal
 // trampoline is used.
 // We will never set this flag, and we should
 // ignore this flag in our diagnostic
 #ifdef SIGNIFICANT_SIGNAL_MASK
 #undef SIGNIFICANT_SIGNAL_MASK
 #endif
 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
 static const char* get_signal_handler_name(address handler,
                                            char* buf, int buflen) {
   int offset;
   bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
   if (found) {
     // skip directory names
     const char *p1, *p2;
     p1 = buf;
     size_t len = strlen(os::file_separator());
     while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
     jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
   } else {
     jio_snprintf(buf, buflen, PTR_FORMAT, handler);
   }
   return buf;
 }
 static void print_signal_handler(outputStream* st, int sig,
                                  char* buf, size_t buflen) {
   struct sigaction sa;
   sigaction(sig, NULL, &sa);
   // See comment for SIGNIFICANT_SIGNAL_MASK define
   sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
   st->print("%s: ", os::exception_name(sig, buf, buflen));
   address handler = (sa.sa_flags & SA_SIGINFO)
     ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
     : CAST_FROM_FN_PTR(address, sa.sa_handler);
   if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
     st->print("SIG_DFL");
   } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
     st->print("SIG_IGN");
   } else {
     st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
   }
   st->print(", sa_mask[0]=");
   os::Posix::print_signal_set_short(st, &sa.sa_mask);
   address rh = VMError::get_resetted_sighandler(sig);
   // May be, handler was resetted by VMError?
   if(rh != NULL) {
     handler = rh;
     sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
   }
   st->print(", sa_flags=");
   os::Posix::print_sa_flags(st, sa.sa_flags);
   // Check: is it our handler?
   if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
      handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
     // It is our signal handler
     // check for flags, reset system-used one!
     if((int)sa.sa_flags != os::Bsd::get_our_sigflags(sig)) {
       st->print(
                 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
                 os::Bsd::get_our_sigflags(sig));
     }
   }
   st->cr();
 }
 #define DO_SIGNAL_CHECK(sig) \
   if (!sigismember(&check_signal_done, sig)) \
     os::Bsd::check_signal_handler(sig)
 // This method is a periodic task to check for misbehaving JNI applications
 // under CheckJNI, we can add any periodic checks here
 void os::run_periodic_checks() {
   if (check_signals == false) return;
   // SEGV and BUS if overridden could potentially prevent
   // generation of hs*.log in the event of a crash, debugging
   // such a case can be very challenging, so we absolutely
   // check the following for a good measure:
   DO_SIGNAL_CHECK(SIGSEGV);
   DO_SIGNAL_CHECK(SIGILL);
   DO_SIGNAL_CHECK(SIGFPE);
   DO_SIGNAL_CHECK(SIGBUS);
   DO_SIGNAL_CHECK(SIGPIPE);
   DO_SIGNAL_CHECK(SIGXFSZ);
   // ReduceSignalUsage allows the user to override these handlers
   // see comments at the very top and jvm_solaris.h
   if (!ReduceSignalUsage) {
     DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
     DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
     DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
     DO_SIGNAL_CHECK(BREAK_SIGNAL);
   }
   DO_SIGNAL_CHECK(SR_signum);
   DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
 }
 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
 static os_sigaction_t os_sigaction = NULL;
 void os::Bsd::check_signal_handler(int sig) {
   char buf[O_BUFLEN];
   address jvmHandler = NULL;
   struct sigaction act;
   if (os_sigaction == NULL) {
     // only trust the default sigaction, in case it has been interposed
     os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
     if (os_sigaction == NULL) return;
   }
   os_sigaction(sig, (struct sigaction*)NULL, &act);
   act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
   address thisHandler = (act.sa_flags & SA_SIGINFO)
     ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
     : CAST_FROM_FN_PTR(address, act.sa_handler) ;
   switch(sig) {
   case SIGSEGV:
   case SIGBUS:
   case SIGFPE:
   case SIGPIPE:
   case SIGILL:
   case SIGXFSZ:
     jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
     break;
   case SHUTDOWN1_SIGNAL:
   case SHUTDOWN2_SIGNAL:
   case SHUTDOWN3_SIGNAL:
   case BREAK_SIGNAL:
     jvmHandler = (address)user_handler();
     break;
   case INTERRUPT_SIGNAL:
     jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
     break;
   default:
     if (sig == SR_signum) {
       jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
     } else {
       return;
     }
     break;
   }
   if (thisHandler != jvmHandler) {
     tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
     tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
     tty->print_cr("  found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
     // No need to check this sig any longer
     sigaddset(&check_signal_done, sig);
     // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
     if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
       tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
                     exception_name(sig, buf, O_BUFLEN));
     }
   } else if(os::Bsd::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Bsd::get_our_sigflags(sig)) {
     tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
     tty->print("expected:" PTR32_FORMAT, os::Bsd::get_our_sigflags(sig));
     tty->print_cr("  found:" PTR32_FORMAT, act.sa_flags);
     // No need to check this sig any longer
     sigaddset(&check_signal_done, sig);
   }
   // Dump all the signal
   if (sigismember(&check_signal_done, sig)) {
     print_signal_handlers(tty, buf, O_BUFLEN);
   }
 }
 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
 extern bool signal_name(int signo, char* buf, size_t len);
 const char* os::exception_name(int exception_code, char* buf, size_t size) {
   if (0 < exception_code && exception_code <= SIGRTMAX) {
     // signal
     if (!signal_name(exception_code, buf, size)) {
       jio_snprintf(buf, size, "SIG%d", exception_code);
     }
     return buf;
   } else {
     return NULL;
   }
 }
 // this is called _before_ the most of global arguments have been parsed
 void os::init(void) {
   char dummy;   /* used to get a guess on initial stack address */
 //  first_hrtime = gethrtime();
   // With BsdThreads the JavaMain thread pid (primordial thread)
   // is different than the pid of the java launcher thread.
   // So, on Bsd, the launcher thread pid is passed to the VM
   // via the sun.java.launcher.pid property.
   // Use this property instead of getpid() if it was correctly passed.
   // See bug 6351349.
   pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
   _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
   clock_tics_per_sec = CLK_TCK;
   init_random(1234567);
   ThreadCritical::initialize();
   Bsd::set_page_size(getpagesize());
   if (Bsd::page_size() == -1) {
     fatal(err_msg("os_bsd.cpp: os::init: sysconf failed (%s)",
                   strerror(errno)));
   }
   init_page_sizes((size_t) Bsd::page_size());
   Bsd::initialize_system_info();
   // main_thread points to the aboriginal thread
   Bsd::_main_thread = pthread_self();
   Bsd::clock_init();
   initial_time_count = javaTimeNanos();
 #ifdef __APPLE__
   // XXXDARWIN
   // Work around the unaligned VM callbacks in hotspot's
   // sharedRuntime. The callbacks don't use SSE2 instructions, and work on
   // Linux, Solaris, and FreeBSD. On Mac OS X, dyld (rightly so) enforces
   // alignment when doing symbol lookup. To work around this, we force early
   // binding of all symbols now, thus binding when alignment is known-good.
   _dyld_bind_fully_image_containing_address((const void *) &os::init);
 #endif
 }
 // To install functions for atexit system call
 extern "C" {
   static void perfMemory_exit_helper() {
     perfMemory_exit();
   }
 }
 // this is called _after_ the global arguments have been parsed
 jint os::init_2(void)
 {
   // Allocate a single page and mark it as readable for safepoint polling
   address polling_page = (address) ::mmap(NULL, Bsd::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
   guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
   os::set_polling_page( polling_page );
 #ifndef PRODUCT
   if(Verbose && PrintMiscellaneous)
     tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
 #endif
   if (!UseMembar) {
     address mem_serialize_page = (address) ::mmap(NULL, Bsd::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
     guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
     os::set_memory_serialize_page( mem_serialize_page );
 #ifndef PRODUCT
     if(Verbose && PrintMiscellaneous)
       tty->print("[Memory Serialize  Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
 #endif
   }
   // initialize suspend/resume support - must do this before signal_sets_init()
   if (SR_initialize() != 0) {
     perror("SR_initialize failed");
     return JNI_ERR;
   }
   Bsd::signal_sets_init();
   Bsd::install_signal_handlers();
   // Check minimum allowable stack size for thread creation and to initialize
   // the java system classes, including StackOverflowError - depends on page
   // size.  Add a page for compiler2 recursion in main thread.
   // Add in 2*BytesPerWord times page size to account for VM stack during
   // class initialization depending on 32 or 64 bit VM.
   os::Bsd::min_stack_allowed = MAX2(os::Bsd::min_stack_allowed,
             (size_t)(StackYellowPages+StackRedPages+StackShadowPages+
 *BytesPerWord COMPILER2_PRESENT(+1)) * Bsd::page_size());
   size_t threadStackSizeInBytes = ThreadStackSize * K;
   if (threadStackSizeInBytes != 0 &&
       threadStackSizeInBytes < os::Bsd::min_stack_allowed) {
         tty->print_cr("\nThe stack size specified is too small, "
                       "Specify at least %dk",
                       os::Bsd::min_stack_allowed/ K);
         return JNI_ERR;
   }
   // Make the stack size a multiple of the page size so that
   // the yellow/red zones can be guarded.
   JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
         vm_page_size()));
   if (MaxFDLimit) {
     // set the number of file descriptors to max. print out error
     // if getrlimit/setrlimit fails but continue regardless.
     struct rlimit nbr_files;
     int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
     if (status != 0) {
       if (PrintMiscellaneous && (Verbose || WizardMode))
         perror("os::init_2 getrlimit failed");
     } else {
       nbr_files.rlim_cur = nbr_files.rlim_max;
 #ifdef __APPLE__
       // Darwin returns RLIM_INFINITY for rlim_max, but fails with EINVAL if
       // you attempt to use RLIM_INFINITY. As per setrlimit(2), OPEN_MAX must
       // be used instead
       nbr_files.rlim_cur = MIN(OPEN_MAX, nbr_files.rlim_cur);
 #endif
       status = setrlimit(RLIMIT_NOFILE, &nbr_files);
       if (status != 0) {
         if (PrintMiscellaneous && (Verbose || WizardMode))
           perror("os::init_2 setrlimit failed");
       }
     }
   }
   // at-exit methods are called in the reverse order of their registration.
   // atexit functions are called on return from main or as a result of a
   // call to exit(3C). There can be only 32 of these functions registered
   // and atexit() does not set errno.
   if (PerfAllowAtExitRegistration) {
     // only register atexit functions if PerfAllowAtExitRegistration is set.
     // atexit functions can be delayed until process exit time, which
     // can be problematic for embedded VM situations. Embedded VMs should
     // call DestroyJavaVM() to assure that VM resources are released.
     // note: perfMemory_exit_helper atexit function may be removed in
     // the future if the appropriate cleanup code can be added to the
     // VM_Exit VMOperation's doit method.
     if (atexit(perfMemory_exit_helper) != 0) {
       warning("os::init2 atexit(perfMemory_exit_helper) failed");
     }
   }
   // initialize thread priority policy
   prio_init();
 #ifdef __APPLE__
   // dynamically link to objective c gc registration
   void *handleLibObjc = dlopen(OBJC_LIB, RTLD_LAZY);
   if (handleLibObjc != NULL) {
     objc_registerThreadWithCollectorFunction = (objc_registerThreadWithCollector_t) dlsym(handleLibObjc, OBJC_GCREGISTER);
   }
 #endif
   return JNI_OK;
 }
 // Mark the polling page as unreadable
 void os::make_polling_page_unreadable(void) {
   if( !guard_memory((char*)_polling_page, Bsd::page_size()) )
     fatal("Could not disable polling page");
 };
 // Mark the polling page as readable
 void os::make_polling_page_readable(void) {
   if( !bsd_mprotect((char *)_polling_page, Bsd::page_size(), PROT_READ)) {
     fatal("Could not enable polling page");
   }
 };
 int os::active_processor_count() {
   return _processor_count;
 }
 void os::set_native_thread_name(const char *name) {
 #if defined(__APPLE__) && MAC_OS_X_VERSION_MIN_REQUIRED > MAC_OS_X_VERSION_10_5
   // This is only supported in Snow Leopard and beyond
   if (name != NULL) {
     // Add a "Java: " prefix to the name
     char buf[MAXTHREADNAMESIZE];
     snprintf(buf, sizeof(buf), "Java: %s", name);
     pthread_setname_np(buf);
   }
 #endif
 }
 bool os::distribute_processes(uint length, uint* distribution) {
   // Not yet implemented.
   return false;
 }
 bool os::bind_to_processor(uint processor_id) {
   // Not yet implemented.
   return false;
 }
 void os::SuspendedThreadTask::internal_do_task() {
   if (do_suspend(_thread->osthread())) {
     SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
     do_task(context);
     do_resume(_thread->osthread());
   }
 }
 ///
 class PcFetcher : public os::SuspendedThreadTask {
 public:
   PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
   ExtendedPC result();
 protected:
   void do_task(const os::SuspendedThreadTaskContext& context);
 private:
   ExtendedPC _epc;
 };
 ExtendedPC PcFetcher::result() {
   guarantee(is_done(), "task is not done yet.");
   return _epc;
 }
 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
   Thread* thread = context.thread();
   OSThread* osthread = thread->osthread();
   if (osthread->ucontext() != NULL) {
     _epc = os::Bsd::ucontext_get_pc((ucontext_t *) context.ucontext());
   } else {
     // NULL context is unexpected, double-check this is the VMThread
     guarantee(thread->is_VM_thread(), "can only be called for VMThread");
   }
 }
 // Suspends the target using the signal mechanism and then grabs the PC before
 // resuming the target. Used by the flat-profiler only
 ExtendedPC os::get_thread_pc(Thread* thread) {
   // Make sure that it is called by the watcher for the VMThread
   assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
   assert(thread->is_VM_thread(), "Can only be called for VMThread");
   PcFetcher fetcher(thread);
   fetcher.run();
   return fetcher.result();
 }
 int os::Bsd::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
 {
   return pthread_cond_timedwait(_cond, _mutex, _abstime);
 }
 ////////////////////////////////////////////////////////////////////////////////
 // debug support
 bool os::find(address addr, outputStream* st) {
   Dl_info dlinfo;
   memset(&dlinfo, 0, sizeof(dlinfo));
   if (dladdr(addr, &dlinfo) != 0) {
     st->print(PTR_FORMAT ": ", addr);
     if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
       st->print("%s+%#x", dlinfo.dli_sname,
                  addr - (intptr_t)dlinfo.dli_saddr);
     } else if (dlinfo.dli_fbase != NULL) {
       st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
     } else {
       st->print("<absolute address>");
     }
     if (dlinfo.dli_fname != NULL) {
       st->print(" in %s", dlinfo.dli_fname);
     }
     if (dlinfo.dli_fbase != NULL) {
       st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
     }
     st->cr();
     if (Verbose) {
       // decode some bytes around the PC
       address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
       address end   = clamp_address_in_page(addr+40, addr, os::vm_page_size());
       address       lowest = (address) dlinfo.dli_sname;
       if (!lowest)  lowest = (address) dlinfo.dli_fbase;
       if (begin < lowest)  begin = lowest;
       Dl_info dlinfo2;
       if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
           && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
         end = (address) dlinfo2.dli_saddr;
       Disassembler::decode(begin, end, st);
     }
     return true;
   }
   return false;
 }
 ////////////////////////////////////////////////////////////////////////////////
 // misc
 // This does not do anything on Bsd. This is basically a hook for being
 // able to use structured exception handling (thread-local exception filters)
 // on, e.g., Win32.
 void
 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
                          JavaCallArguments* args, Thread* thread) {
   f(value, method, args, thread);
 }
 void os::print_statistics() {
 }
 int os::message_box(const char* title, const char* message) {
   int i;
   fdStream err(defaultStream::error_fd());
   for (i = 0; i < 78; i++) err.print_raw("=");
   err.cr();
   err.print_raw_cr(title);
   for (i = 0; i < 78; i++) err.print_raw("-");
   err.cr();
   err.print_raw_cr(message);
   for (i = 0; i < 78; i++) err.print_raw("=");
   err.cr();
   char buf[16];
   // Prevent process from exiting upon "read error" without consuming all CPU
   while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
   return buf[0] == 'y' || buf[0] == 'Y';
 }
 int os::stat(const char *path, struct stat *sbuf) {
   char pathbuf[MAX_PATH];
   if (strlen(path) > MAX_PATH - 1) {
     errno = ENAMETOOLONG;
     return -1;
   }
   os::native_path(strcpy(pathbuf, path));
   return ::stat(pathbuf, sbuf);
 }
 bool os::check_heap(bool force) {
   return true;
 }
 ATTRIBUTE_PRINTF(3, 0)
 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
   return ::vsnprintf(buf, count, format, args);
 }
 // Is a (classpath) directory empty?
 bool os::dir_is_empty(const char* path) {
   DIR *dir = NULL;
   struct dirent *ptr;
   dir = opendir(path);
   if (dir == NULL) return true;
   /* Scan the directory */
   bool result = true;
   char buf[sizeof(struct dirent) + MAX_PATH];
   while (result && (ptr = ::readdir(dir)) != NULL) {
     if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
       result = false;
     }
   }
   closedir(dir);
   return result;
 }
 // This code originates from JDK's sysOpen and open64_w
 // from src/solaris/hpi/src/system_md.c
 #ifndef O_DELETE
 #define O_DELETE 0x10000
 #endif
 // Open a file. Unlink the file immediately after open returns
 // if the specified oflag has the O_DELETE flag set.
 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
 int os::open(const char *path, int oflag, int mode) {
   if (strlen(path) > MAX_PATH - 1) {
     errno = ENAMETOOLONG;
     return -1;
   }
   int fd;
   int o_delete = (oflag & O_DELETE);
   oflag = oflag & ~O_DELETE;
   fd = ::open(path, oflag, mode);
   if (fd == -1) return -1;
   //If the open succeeded, the file might still be a directory
   {
     struct stat buf;
     int ret = ::fstat(fd, &buf);
     int st_mode = buf.st_mode;
     if (ret != -1) {
       if ((st_mode & S_IFMT) == S_IFDIR) {
         errno = EISDIR;
         ::close(fd);
         return -1;
       }
     } else {
       ::close(fd);
       return -1;
     }
   }
     /*
      * All file descriptors that are opened in the JVM and not
      * specifically destined for a subprocess should have the
      * close-on-exec flag set.  If we don't set it, then careless 3rd
      * party native code might fork and exec without closing all
      * appropriate file descriptors (e.g. as we do in closeDescriptors in
      * UNIXProcess.c), and this in turn might:
      *
      * - cause end-of-file to fail to be detected on some file
      *   descriptors, resulting in mysterious hangs, or
      *
      * - might cause an fopen in the subprocess to fail on a system
      *   suffering from bug 1085341.
      *
      * (Yes, the default setting of the close-on-exec flag is a Unix
      * design flaw)
      *
      * See:
      * 1085341: 32-bit stdio routines should support file descriptors >255
      * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
      * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
      */
 #ifdef FD_CLOEXEC
     {
         int flags = ::fcntl(fd, F_GETFD);
         if (flags != -1)
             ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
     }
 #endif
   if (o_delete != 0) {
     ::unlink(path);
   }
   return fd;
 }
 // create binary file, rewriting existing file if required
 int os::create_binary_file(const char* path, bool rewrite_existing) {
   int oflags = O_WRONLY | O_CREAT;
   if (!rewrite_existing) {
     oflags |= O_EXCL;
   }
   return ::open(path, oflags, S_IREAD | S_IWRITE);
 }
 // return current position of file pointer
 jlong os::current_file_offset(int fd) {
   return (jlong)::lseek(fd, (off_t)0, SEEK_CUR);
 }
 // move file pointer to the specified offset
 jlong os::seek_to_file_offset(int fd, jlong offset) {
   return (jlong)::lseek(fd, (off_t)offset, SEEK_SET);
 }
 // This code originates from JDK's sysAvailable
 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
 int os::available(int fd, jlong *bytes) {
   jlong cur, end;
   int mode;
   struct stat buf;
   if (::fstat(fd, &buf) >= 0) {
     mode = buf.st_mode;
     if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
       /*
       * XXX: is the following call interruptible? If so, this might
       * need to go through the INTERRUPT_IO() wrapper as for other
       * blocking, interruptible calls in this file.
       */
       int n;
       if (::ioctl(fd, FIONREAD, &n) >= 0) {
         *bytes = n;
         return 1;
       }
     }
   }
   if ((cur = ::lseek(fd, 0L, SEEK_CUR)) == -1) {
     return 0;
   } else if ((end = ::lseek(fd, 0L, SEEK_END)) == -1) {
     return 0;
   } else if (::lseek(fd, cur, SEEK_SET) == -1) {
     return 0;
   }
   *bytes = end - cur;
   return 1;
 }
 int os::socket_available(int fd, jint *pbytes) {
    if (fd < 0)
      return OS_OK;
    int ret;
    RESTARTABLE(::ioctl(fd, FIONREAD, pbytes), ret);
    //%% note ioctl can return 0 when successful, JVM_SocketAvailable
    // is expected to return 0 on failure and 1 on success to the jdk.
    return (ret == OS_ERR) ? 0 : 1;
 }
 // Map a block of memory.
 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
                      char *addr, size_t bytes, bool read_only,
                      bool allow_exec) {
   int prot;
   int flags;
   if (read_only) {
     prot = PROT_READ;
     flags = MAP_SHARED;
   } else {
     prot = PROT_READ | PROT_WRITE;
     flags = MAP_PRIVATE;
   }
   if (allow_exec) {
     prot |= PROT_EXEC;
   }
   if (addr != NULL) {
     flags |= MAP_FIXED;
   }
   char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
                                      fd, file_offset);
   if (mapped_address == MAP_FAILED) {
     return NULL;
   }
   return mapped_address;
 }
 // Remap a block of memory.
 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
                        char *addr, size_t bytes, bool read_only,
                        bool allow_exec) {
   // same as map_memory() on this OS
   return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
                         allow_exec);
 }
 // Unmap a block of memory.
 bool os::pd_unmap_memory(char* addr, size_t bytes) {
   return munmap(addr, bytes) == 0;
 }
 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
 // of a thread.
 //
 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
 // the fast estimate available on the platform.
 jlong os::current_thread_cpu_time() {
 #ifdef __APPLE__
   return os::thread_cpu_time(Thread::current(), true /* user + sys */);
 #else
   Unimplemented();
   return 0;
 #endif
 }
 jlong os::thread_cpu_time(Thread* thread) {
 #ifdef __APPLE__
   return os::thread_cpu_time(thread, true /* user + sys */);
 #else
   Unimplemented();
   return 0;
 #endif
 }
 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
 #ifdef __APPLE__
   return os::thread_cpu_time(Thread::current(), user_sys_cpu_time);
 #else
   Unimplemented();
   return 0;
 #endif
 }
 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
 #ifdef __APPLE__
   struct thread_basic_info tinfo;
   mach_msg_type_number_t tcount = THREAD_INFO_MAX;
   kern_return_t kr;
   thread_t mach_thread;
   mach_thread = thread->osthread()->thread_id();
   kr = thread_info(mach_thread, THREAD_BASIC_INFO, (thread_info_t)&tinfo, &tcount);
   if (kr != KERN_SUCCESS)
     return -1;
   if (user_sys_cpu_time) {
     jlong nanos;
     nanos = ((jlong) tinfo.system_time.seconds + tinfo.user_time.seconds) * (jlong)1000000000;
     nanos += ((jlong) tinfo.system_time.microseconds + (jlong) tinfo.user_time.microseconds) * (jlong)1000;
     return nanos;
   } else {
     return ((jlong)tinfo.user_time.seconds * 1000000000) + ((jlong)tinfo.user_time.microseconds * (jlong)1000);
   }
 #else
   Unimplemented();
   return 0;
 #endif
 }
 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
   info_ptr->max_value = ALL_64_BITS;       // will not wrap in less than 64 bits
   info_ptr->may_skip_backward = false;     // elapsed time not wall time
   info_ptr->may_skip_forward = false;      // elapsed time not wall time
   info_ptr->kind = JVMTI_TIMER_TOTAL_CPU;  // user+system time is returned
 }
 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
   info_ptr->max_value = ALL_64_BITS;       // will not wrap in less than 64 bits
   info_ptr->may_skip_backward = false;     // elapsed time not wall time
   info_ptr->may_skip_forward = false;      // elapsed time not wall time
   info_ptr->kind = JVMTI_TIMER_TOTAL_CPU;  // user+system time is returned
 }
 bool os::is_thread_cpu_time_supported() {
 #ifdef __APPLE__
   return true;
 #else
   return false;
 #endif
 }
 // System loadavg support.  Returns -1 if load average cannot be obtained.
 // Bsd doesn't yet have a (official) notion of processor sets,
 // so just return the system wide load average.
 int os::loadavg(double loadavg[], int nelem) {
   return ::getloadavg(loadavg, nelem);
 }
 void os::pause() {
   char filename[MAX_PATH];
   if (PauseAtStartupFile && PauseAtStartupFile[0]) {
     jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
   } else {
     jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
   }
   int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
   if (fd != -1) {
     struct stat buf;
     ::close(fd);
     while (::stat(filename, &buf) == 0) {
       (void)::poll(NULL, 0, 100);
     }
   } else {
     jio_fprintf(stderr,
       "Could not open pause file '%s', continuing immediately.\n", filename);
   }
 }
 // Refer to the comments in os_solaris.cpp park-unpark.
 //
 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
 // hang indefinitely.  For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
 // For specifics regarding the bug see GLIBC BUGID 261237 :
 //    http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
 // is used.  (The simple C test-case provided in the GLIBC bug report manifests the
 // hang).  The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
 // and monitorenter when we're using 1-0 locking.  All those operations may result in
 // calls to pthread_cond_timedwait().  Using LD_ASSUME_KERNEL to use an older version
 // of libpthread avoids the problem, but isn't practical.
 //
 // Possible remedies:
 //
 // 1.   Establish a minimum relative wait time.  50 to 100 msecs seems to work.
 //      This is palliative and probabilistic, however.  If the thread is preempted
 //      between the call to compute_abstime() and pthread_cond_timedwait(), more
 //      than the minimum period may have passed, and the abstime may be stale (in the
 //      past) resultin in a hang.   Using this technique reduces the odds of a hang
 //      but the JVM is still vulnerable, particularly on heavily loaded systems.
 //
 // 2.   Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
 //      of the usual flag-condvar-mutex idiom.  The write side of the pipe is set
 //      NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
 //      reduces to poll()+read().  This works well, but consumes 2 FDs per extant
 //      thread.
 //
 // 3.   Embargo pthread_cond_timedwait() and implement a native "chron" thread
 //      that manages timeouts.  We'd emulate pthread_cond_timedwait() by enqueuing
 //      a timeout request to the chron thread and then blocking via pthread_cond_wait().
 //      This also works well.  In fact it avoids kernel-level scalability impediments
 //      on certain platforms that don't handle lots of active pthread_cond_timedwait()
 //      timers in a graceful fashion.
 //
 // 4.   When the abstime value is in the past it appears that control returns
 //      correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
 //      Subsequent timedwait/wait calls may hang indefinitely.  Given that, we
 //      can avoid the problem by reinitializing the condvar -- by cond_destroy()
 //      followed by cond_init() -- after all calls to pthread_cond_timedwait().
 //      It may be possible to avoid reinitialization by checking the return
 //      value from pthread_cond_timedwait().  In addition to reinitializing the
 //      condvar we must establish the invariant that cond_signal() is only called
 //      within critical sections protected by the adjunct mutex.  This prevents
 //      cond_signal() from "seeing" a condvar that's in the midst of being
 //      reinitialized or that is corrupt.  Sadly, this invariant obviates the
 //      desirable signal-after-unlock optimization that avoids futile context switching.
 //
 //      I'm also concerned that some versions of NTPL might allocate an auxilliary
 //      structure when a condvar is used or initialized.  cond_destroy()  would
 //      release the helper structure.  Our reinitialize-after-timedwait fix
 //      put excessive stress on malloc/free and locks protecting the c-heap.
 //
 // We currently use (4).  See the WorkAroundNTPLTimedWaitHang flag.
 // It may be possible to refine (4) by checking the kernel and NTPL verisons
 // and only enabling the work-around for vulnerable environments.
 // utility to compute the abstime argument to timedwait:
 // millis is the relative timeout time
 // abstime will be the absolute timeout time
 // TODO: replace compute_abstime() with unpackTime()
 static struct timespec* compute_abstime(struct timespec* abstime, jlong millis) {
   if (millis < 0)  millis = 0;
   struct timeval now;
   int status = gettimeofday(&now, NULL);
   assert(status == 0, "gettimeofday");
   jlong seconds = millis / 1000;
   millis %= 1000;
   if (seconds > 50000000) { // see man cond_timedwait(3T)
     seconds = 50000000;
   }
   abstime->tv_sec = now.tv_sec  + seconds;
   long       usec = now.tv_usec + millis * 1000;
   if (usec >= 1000000) {
     abstime->tv_sec += 1;
     usec -= 1000000;
   }
   abstime->tv_nsec = usec * 1000;
   return abstime;
 }
 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
 // Conceptually TryPark() should be equivalent to park(0).
 int os::PlatformEvent::TryPark() {
   for (;;) {
     const int v = _Event ;
     guarantee ((v == 0) || (v == 1), "invariant") ;
     if (Atomic::cmpxchg (0, &_Event, v) == v) return v  ;
   }
 }
 void os::PlatformEvent::park() {       // AKA "down()"
   // Invariant: Only the thread associated with the Event/PlatformEvent
   // may call park().
   // TODO: assert that _Assoc != NULL or _Assoc == Self
   int v ;
   for (;;) {
       v = _Event ;
       if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
   }
   guarantee (v >= 0, "invariant") ;
   if (v == 0) {
      // Do this the hard way by blocking ...
      int status = pthread_mutex_lock(_mutex);
      assert_status(status == 0, status, "mutex_lock");
      guarantee (_nParked == 0, "invariant") ;
      ++ _nParked ;
      while (_Event < 0) {
         status = pthread_cond_wait(_cond, _mutex);
         // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
         // Treat this the same as if the wait was interrupted
         if (status == ETIMEDOUT) { status = EINTR; }
         assert_status(status == 0 || status == EINTR, status, "cond_wait");
      }
      -- _nParked ;
     _Event = 0 ;
      status = pthread_mutex_unlock(_mutex);
      assert_status(status == 0, status, "mutex_unlock");
     // Paranoia to ensure our locked and lock-free paths interact
     // correctly with each other.
     OrderAccess::fence();
   }
   guarantee (_Event >= 0, "invariant") ;
 }
 int os::PlatformEvent::park(jlong millis) {
   guarantee (_nParked == 0, "invariant") ;
   int v ;
   for (;;) {
       v = _Event ;
       if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
   }
   guarantee (v >= 0, "invariant") ;
   if (v != 0) return OS_OK ;
   // We do this the hard way, by blocking the thread.
   // Consider enforcing a minimum timeout value.
   struct timespec abst;
   compute_abstime(&abst, millis);
   int ret = OS_TIMEOUT;
   int status = pthread_mutex_lock(_mutex);
   assert_status(status == 0, status, "mutex_lock");
   guarantee (_nParked == 0, "invariant") ;
   ++_nParked ;
   // Object.wait(timo) will return because of
   // (a) notification
   // (b) timeout
   // (c) thread.interrupt
   //
   // Thread.interrupt and object.notify{All} both call Event::set.
   // That is, we treat thread.interrupt as a special case of notification.
   // The underlying Solaris implementation, cond_timedwait, admits
   // spurious/premature wakeups, but the JLS/JVM spec prevents the
   // JVM from making those visible to Java code.  As such, we must
   // filter out spurious wakeups.  We assume all ETIME returns are valid.
   //
   // TODO: properly differentiate simultaneous notify+interrupt.
   // In that case, we should propagate the notify to another waiter.
   while (_Event < 0) {
     status = os::Bsd::safe_cond_timedwait(_cond, _mutex, &abst);
     if (status != 0 && WorkAroundNPTLTimedWaitHang) {
       pthread_cond_destroy (_cond);
       pthread_cond_init (_cond, NULL) ;
     }
     assert_status(status == 0 || status == EINTR ||
                   status == ETIMEDOUT,
                   status, "cond_timedwait");
     if (!FilterSpuriousWakeups) break ;                 // previous semantics
     if (status == ETIMEDOUT) break ;
     // We consume and ignore EINTR and spurious wakeups.
   }
   --_nParked ;
   if (_Event >= 0) {
      ret = OS_OK;
   }
   _Event = 0 ;
   status = pthread_mutex_unlock(_mutex);
   assert_status(status == 0, status, "mutex_unlock");
   assert (_nParked == 0, "invariant") ;
   // Paranoia to ensure our locked and lock-free paths interact
   // correctly with each other.
   OrderAccess::fence();
   return ret;
 }
 void os::PlatformEvent::unpark() {
   // Transitions for _Event:
   //    0 :=> 1
   //    1 :=> 1
   //   -1 :=> either 0 or 1; must signal target thread
   //          That is, we can safely transition _Event from -1 to either
   //          0 or 1. Forcing 1 is slightly more efficient for back-to-back
   //          unpark() calls.
   // See also: "Semaphores in Plan 9" by Mullender & Cox
   //
   // Note: Forcing a transition from "-1" to "1" on an unpark() means
   // that it will take two back-to-back park() calls for the owning
   // thread to block. This has the benefit of forcing a spurious return
   // from the first park() call after an unpark() call which will help
   // shake out uses of park() and unpark() without condition variables.
   if (Atomic::xchg(1, &_Event) >= 0) return;
   // Wait for the thread associated with the event to vacate
   int status = pthread_mutex_lock(_mutex);
   assert_status(status == 0, status, "mutex_lock");
   int AnyWaiters = _nParked;
   assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
   if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
     AnyWaiters = 0;
     pthread_cond_signal(_cond);
   }
   status = pthread_mutex_unlock(_mutex);
   assert_status(status == 0, status, "mutex_unlock");
   if (AnyWaiters != 0) {
     status = pthread_cond_signal(_cond);
     assert_status(status == 0, status, "cond_signal");
   }
   // Note that we signal() _after dropping the lock for "immortal" Events.
   // This is safe and avoids a common class of  futile wakeups.  In rare
   // circumstances this can cause a thread to return prematurely from
   // cond_{timed}wait() but the spurious wakeup is benign and the victim will
   // simply re-test the condition and re-park itself.
 }
 // JSR166
 // -------------------------------------------------------
 /*
  * The solaris and bsd implementations of park/unpark are fairly
  * conservative for now, but can be improved. They currently use a
  * mutex/condvar pair, plus a a count.
  * Park decrements count if > 0, else does a condvar wait.  Unpark
  * sets count to 1 and signals condvar.  Only one thread ever waits
  * on the condvar. Contention seen when trying to park implies that someone
  * is unparking you, so don't wait. And spurious returns are fine, so there
  * is no need to track notifications.
  */
 #define MAX_SECS 100000000
 /*
  * This code is common to bsd and solaris and will be moved to a
  * common place in dolphin.
  *
  * The passed in time value is either a relative time in nanoseconds
  * or an absolute time in milliseconds. Either way it has to be unpacked
  * into suitable seconds and nanoseconds components and stored in the
  * given timespec structure.
  * Given time is a 64-bit value and the time_t used in the timespec is only
  * a signed-32-bit value (except on 64-bit Bsd) we have to watch for
  * overflow if times way in the future are given. Further on Solaris versions
  * prior to 10 there is a restriction (see cond_timedwait) that the specified
  * number of seconds, in abstime, is less than current_time  + 100,000,000.
  * As it will be 28 years before "now + 100000000" will overflow we can
  * ignore overflow and just impose a hard-limit on seconds using the value
  * of "now + 100,000,000". This places a limit on the timeout of about 3.17
  * years from "now".
  */
 static void unpackTime(struct timespec* absTime, bool isAbsolute, jlong time) {
   assert (time > 0, "convertTime");
   struct timeval now;
   int status = gettimeofday(&now, NULL);
   assert(status == 0, "gettimeofday");
   time_t max_secs = now.tv_sec + MAX_SECS;
   if (isAbsolute) {
     jlong secs = time / 1000;
     if (secs > max_secs) {
       absTime->tv_sec = max_secs;
     }
     else {
       absTime->tv_sec = secs;
     }
     absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
   }
   else {
     jlong secs = time / NANOSECS_PER_SEC;
     if (secs >= MAX_SECS) {
       absTime->tv_sec = max_secs;
       absTime->tv_nsec = 0;
     }
     else {
       absTime->tv_sec = now.tv_sec + secs;
       absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
       if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
         absTime->tv_nsec -= NANOSECS_PER_SEC;
         ++absTime->tv_sec; // note: this must be <= max_secs
       }
     }
   }
   assert(absTime->tv_sec >= 0, "tv_sec < 0");
   assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
   assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
   assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
 }
 void Parker::park(bool isAbsolute, jlong time) {
   // Ideally we'd do something useful while spinning, such
   // as calling unpackTime().
   // Optional fast-path check:
   // Return immediately if a permit is available.
   // We depend on Atomic::xchg() having full barrier semantics
   // since we are doing a lock-free update to _counter.
   if (Atomic::xchg(0, &_counter) > 0) return;
   Thread* thread = Thread::current();
   assert(thread->is_Java_thread(), "Must be JavaThread");
   JavaThread *jt = (JavaThread *)thread;
   // Optional optimization -- avoid state transitions if there's an interrupt pending.
   // Check interrupt before trying to wait
   if (Thread::is_interrupted(thread, false)) {
     return;
   }
   // Next, demultiplex/decode time arguments
   struct timespec absTime;
   if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
     return;
   }
   if (time > 0) {
     unpackTime(&absTime, isAbsolute, time);
   }
   // Enter safepoint region
   // Beware of deadlocks such as 6317397.
   // The per-thread Parker:: mutex is a classic leaf-lock.
   // In particular a thread must never block on the Threads_lock while
   // holding the Parker:: mutex.  If safepoints are pending both the
   // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
   ThreadBlockInVM tbivm(jt);
   // Don't wait if cannot get lock since interference arises from
   // unblocking.  Also. check interrupt before trying wait
   if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
     return;
   }
   int status ;
   if (_counter > 0)  { // no wait needed
     _counter = 0;
     status = pthread_mutex_unlock(_mutex);
     assert (status == 0, "invariant") ;
     // Paranoia to ensure our locked and lock-free paths interact
     // correctly with each other and Java-level accesses.
     OrderAccess::fence();
     return;
   }
 #ifdef ASSERT
   // Don't catch signals while blocked; let the running threads have the signals.
   // (This allows a debugger to break into the running thread.)
   sigset_t oldsigs;
   sigset_t* allowdebug_blocked = os::Bsd::allowdebug_blocked_signals();
   pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
 #endif
   OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
   jt->set_suspend_equivalent();
   // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
   if (time == 0) {
     status = pthread_cond_wait (_cond, _mutex) ;
   } else {
     status = os::Bsd::safe_cond_timedwait (_cond, _mutex, &absTime) ;
     if (status != 0 && WorkAroundNPTLTimedWaitHang) {
       pthread_cond_destroy (_cond) ;
       pthread_cond_init    (_cond, NULL);
     }
   }
   assert_status(status == 0 || status == EINTR ||
                 status == ETIMEDOUT,
                 status, "cond_timedwait");
 #ifdef ASSERT
   pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
 #endif
   _counter = 0 ;
   status = pthread_mutex_unlock(_mutex) ;
   assert_status(status == 0, status, "invariant") ;
   // Paranoia to ensure our locked and lock-free paths interact
   // correctly with each other and Java-level accesses.
   OrderAccess::fence();
   // If externally suspended while waiting, re-suspend
   if (jt->handle_special_suspend_equivalent_condition()) {
     jt->java_suspend_self();
   }
 }
 void Parker::unpark() {
   int s, status ;
   status = pthread_mutex_lock(_mutex);
   assert (status == 0, "invariant") ;
   s = _counter;
   _counter = 1;
   if (s < 1) {
      if (WorkAroundNPTLTimedWaitHang) {
         status = pthread_cond_signal (_cond) ;
         assert (status == 0, "invariant") ;
         status = pthread_mutex_unlock(_mutex);
         assert (status == 0, "invariant") ;
      } else {
         status = pthread_mutex_unlock(_mutex);
         assert (status == 0, "invariant") ;
         status = pthread_cond_signal (_cond) ;
         assert (status == 0, "invariant") ;
      }
   } else {
     pthread_mutex_unlock(_mutex);
     assert (status == 0, "invariant") ;
   }
 }
 /* Darwin has no "environ" in a dynamic library. */
 #ifdef __APPLE__
 #include <crt_externs.h>
 #define environ (*_NSGetEnviron())
 #else
 extern char** environ;
 #endif
 // Run the specified command in a separate process. Return its exit value,
 // or -1 on failure (e.g. can't fork a new process).
 // Unlike system(), this function can be called from signal handler. It
 // doesn't block SIGINT et al.
 int os::fork_and_exec(char* cmd) {
   const char * argv[4] = {"sh", "-c", cmd, NULL};
   // fork() in BsdThreads/NPTL is not async-safe. It needs to run
   // pthread_atfork handlers and reset pthread library. All we need is a
   // separate process to execve. Make a direct syscall to fork process.
   // On IA64 there's no fork syscall, we have to use fork() and hope for
   // the best...
   pid_t pid = fork();
   if (pid < 0) {
     // fork failed
     return -1;
   } else if (pid == 0) {
     // child process
     // execve() in BsdThreads will call pthread_kill_other_threads_np()
     // first to kill every thread on the thread list. Because this list is
     // not reset by fork() (see notes above), execve() will instead kill
     // every thread in the parent process. We know this is the only thread
     // in the new process, so make a system call directly.
     // IA64 should use normal execve() from glibc to match the glibc fork()
     // above.
     execve("/bin/sh", (char* const*)argv, environ);
     // execve failed
     _exit(-1);
   } else  {
     // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
     // care about the actual exit code, for now.
     int status;
     // Wait for the child process to exit.  This returns immediately if
     // the child has already exited. */
     while (waitpid(pid, &status, 0) < 0) {
         switch (errno) {
         case ECHILD: return 0;
         case EINTR: break;
         default: return -1;
         }
     }
     if (WIFEXITED(status)) {
        // The child exited normally; get its exit code.
        return WEXITSTATUS(status);
     } else if (WIFSIGNALED(status)) {
        // The child exited because of a signal
        // The best value to return is 0x80 + signal number,
        // because that is what all Unix shells do, and because
        // it allows callers to distinguish between process exit and
        // process death by signal.
        return 0x80 + WTERMSIG(status);
     } else {
        // Unknown exit code; pass it through
        return status;
     }
   }
 }
 // is_headless_jre()
 //
 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
 // in order to report if we are running in a headless jre
 //
 // Since JDK8 xawt/libmawt.so was moved into the same directory
 // as libawt.so, and renamed libawt_xawt.so
 //
 bool os::is_headless_jre() {
 #ifdef __APPLE__
     // We no longer build headless-only on Mac OS X
     return false;
 #else
     struct stat statbuf;
     char buf[MAXPATHLEN];
     char libmawtpath[MAXPATHLEN];
     const char *xawtstr  = "/xawt/libmawt" JNI_LIB_SUFFIX;
     const char *new_xawtstr = "/libawt_xawt" JNI_LIB_SUFFIX;
     char *p;
     // Get path to libjvm.so
     os::jvm_path(buf, sizeof(buf));
     // Get rid of libjvm.so
     p = strrchr(buf, '/');
     if (p == NULL) return false;
     else *p = '\0';
     // Get rid of client or server
     p = strrchr(buf, '/');
     if (p == NULL) return false;
     else *p = '\0';
     // check xawt/libmawt.so
     strcpy(libmawtpath, buf);
     strcat(libmawtpath, xawtstr);
     if (::stat(libmawtpath, &statbuf) == 0) return false;
     // check libawt_xawt.so
     strcpy(libmawtpath, buf);
     strcat(libmawtpath, new_xawtstr);
     if (::stat(libmawtpath, &statbuf) == 0) return false;
     return true;
 #endif
 }
 // Get the default path to the core file
 // Returns the length of the string
 int os::get_core_path(char* buffer, size_t bufferSize) {
   int n = jio_snprintf(buffer, bufferSize, "/cores");
   // Truncate if theoretical string was longer than bufferSize
   n = MIN2(n, (int)bufferSize);
   return n;
 }
 #ifndef PRODUCT
 void TestReserveMemorySpecial_test() {
   // No tests available for this platform
 }
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/os/bsd/vm/os_bsd.cpp@2d23269a45a0 (annotated)

src/os/bsd/vm/os_bsd.cpp