Mercurial > hg > truffle
view src/os/linux/vm/os_linux.cpp @ 1378:9f5b60a14736
6939930: exception unwind changes in 6919934 hurts compilation speed
Reviewed-by: twisti
author | never |
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date | Thu, 15 Apr 2010 18:14:49 -0700 |
parents | a2ea687fdc7c |
children | f03d0a26bf83 96d554193f72 |
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/* * Copyright 1999-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ # define __STDC_FORMAT_MACROS // do not include precompiled header file # include "incls/_os_linux.cpp.incl" // put OS-includes here # include <sys/types.h> # include <sys/mman.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 <pwd.h> # include <poll.h> # include <semaphore.h> # include <fcntl.h> # include <string.h> # include <syscall.h> # include <sys/sysinfo.h> # include <gnu/libc-version.h> # include <sys/ipc.h> # include <sys/shm.h> # include <link.h> # include <stdint.h> # include <inttypes.h> #define MAX_PATH (2 * K) // for timer info max values which include all bits #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF) #define SEC_IN_NANOSECS 1000000000LL //////////////////////////////////////////////////////////////////////////////// // global variables julong os::Linux::_physical_memory = 0; address os::Linux::_initial_thread_stack_bottom = NULL; uintptr_t os::Linux::_initial_thread_stack_size = 0; int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL; int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL; Mutex* os::Linux::_createThread_lock = NULL; pthread_t os::Linux::_main_thread; int os::Linux::_page_size = -1; bool os::Linux::_is_floating_stack = false; bool os::Linux::_is_NPTL = false; bool os::Linux::_supports_fast_thread_cpu_time = false; const char * os::Linux::_glibc_version = NULL; const char * os::Linux::_libpthread_version = NULL; 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; /* Used to protect dlsym() calls */ static pthread_mutex_t dl_mutex; //////////////////////////////////////////////////////////////////////////////// // utility functions static int SR_initialize(); static int SR_finalize(); julong os::available_memory() { return Linux::available_memory(); } julong os::Linux::available_memory() { // values in struct sysinfo are "unsigned long" struct sysinfo si; sysinfo(&si); return (julong)si.freeram * si.mem_unit; } julong os::physical_memory() { return Linux::physical_memory(); } julong os::allocatable_physical_memory(julong size) { #ifdef _LP64 return size; #else julong result = MIN2(size, (julong)3800*M); if (!is_allocatable(result)) { // See comments under solaris for alignment considerations julong reasonable_size = (julong)2*G - 2 * os::vm_page_size(); result = MIN2(size, reasonable_size); } return result; #endif // _LP64 } //////////////////////////////////////////////////////////////////////////////// // 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; } #ifndef SYS_gettid // i386: 224, ia64: 1105, amd64: 186, sparc 143 #ifdef __ia64__ #define SYS_gettid 1105 #elif __i386__ #define SYS_gettid 224 #elif __amd64__ #define SYS_gettid 186 #elif __sparc__ #define SYS_gettid 143 #else #error define gettid for the arch #endif #endif // 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(SPARC) # ifdef _LP64 static char cpu_arch[] = "sparcv9"; # else static char cpu_arch[] = "sparc"; # endif #else #error Add appropriate cpu_arch setting #endif // pid_t gettid() // // Returns the kernel thread id of the currently running thread. Kernel // thread id is used to access /proc. // // (Note that getpid() on LinuxThreads returns kernel thread id too; but // on NPTL, it returns the same pid for all threads, as required by POSIX.) // pid_t os::Linux::gettid() { int rslt = syscall(SYS_gettid); if (rslt == -1) { // old kernel, no NPTL support return getpid(); } else { return (pid_t)rslt; } } // Most versions of linux have a bug where the number of processors are // determined by looking at the /proc file system. In a chroot environment, // the system call returns 1. This causes the VM to act as if it is // a single processor and elide locking (see is_MP() call). static bool unsafe_chroot_detected = false; static const char *unstable_chroot_error = "/proc file system not found.\n" "Java may be unstable running multithreaded in a chroot " "environment on Linux when /proc filesystem is not mounted."; void os::Linux::initialize_system_info() { set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); if (processor_count() == 1) { pid_t pid = os::Linux::gettid(); char fname[32]; jio_snprintf(fname, sizeof(fname), "/proc/%d", pid); FILE *fp = fopen(fname, "r"); if (fp == NULL) { unsafe_chroot_detected = true; } else { fclose(fp); } } _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE); assert(processor_count() > 0, "linux error"); } void os::init_system_properties_values() { // char arch[12]; // sysinfo(SI_ARCHITECTURE, arch, sizeof(arch)); // The next steps are taken in the product version: // // Obtain the JAVA_HOME value from the location of libjvm[_g].so. // This library should be located at: // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm[_g].so. // // If "/jre/lib/" appears at the right place in the path, then we // assume libjvm[_g].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[_g].so" to this path so // it looks like libjvm[_g].so is installed there // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm[_g].so. // // Otherwise exit. // // Important note: if the location of libjvm.so changes this // code needs to be changed accordingly. // The next few definitions allow the code to be verbatim: #define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n)) #define getenv(n) ::getenv(n) /* * 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. */ #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390)) #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib" #else #define DEFAULT_LIBPATH "/lib:/usr/lib" #endif #define EXTENSIONS_DIR "/lib/ext" #define ENDORSED_DIR "/lib/endorsed" #define REG_DIR "/usr/java/packages" { /* sysclasspath, java_home, dll_dir */ { char *home_path; char *dll_path; char *pslash; char buf[MAXPATHLEN]; os::jvm_path(buf, sizeof(buf)); // 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} */ dll_path = malloc(strlen(buf) + 1); if (dll_path == NULL) return; strcpy(dll_path, buf); Arguments::set_dll_dir(dll_path); 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 */ } } home_path = malloc(strlen(buf) + 1); if (home_path == NULL) return; strcpy(home_path, buf); Arguments::set_java_home(home_path); if (!set_boot_path('/', ':')) return; } /* * 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 Linux 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. */ { char *ld_library_path; /* * Construct the invariant part of ld_library_path. Note that the * space for the colon and the trailing null are provided by the * nulls included by the sizeof operator (so actually we allocate * a byte more than necessary). */ ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH)); sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch); /* * Get the user setting of LD_LIBRARY_PATH, and prepended it. It * should always exist (until the legacy problem cited above is * addressed). */ char *v = getenv("LD_LIBRARY_PATH"); if (v != NULL) { char *t = ld_library_path; /* That's +1 for the colon and +1 for the trailing '\0' */ ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1); sprintf(ld_library_path, "%s:%s", v, t); } Arguments::set_library_path(ld_library_path); } /* * 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). */ { char *buf = malloc(strlen(Arguments::get_java_home()) + sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR)); sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR, Arguments::get_java_home()); Arguments::set_ext_dirs(buf); } /* Endorsed standards default directory. */ { char * buf; buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR)); sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home()); Arguments::set_endorsed_dirs(buf); } } #undef malloc #undef getenv #undef EXTENSIONS_DIR #undef ENDORSED_DIR // Done return; } //////////////////////////////////////////////////////////////////////////////// // 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::Linux::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::Linux::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::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) { sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL); sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL); } if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) { sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL); sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL); } if (!os::Linux::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::Linux::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::Linux::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::Linux::allowdebug_blocked_signals() { assert(signal_sets_initialized, "Not initialized"); return &allowdebug_blocked_sigs; } void os::Linux::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::Linux::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); } } } ////////////////////////////////////////////////////////////////////////////// // detecting pthread library void os::Linux::libpthread_init() { // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a // generic name for earlier versions. // Define macros here so we can build HotSpot on old systems. # ifndef _CS_GNU_LIBC_VERSION # define _CS_GNU_LIBC_VERSION 2 # endif # ifndef _CS_GNU_LIBPTHREAD_VERSION # define _CS_GNU_LIBPTHREAD_VERSION 3 # endif size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0); if (n > 0) { char *str = (char *)malloc(n); confstr(_CS_GNU_LIBC_VERSION, str, n); os::Linux::set_glibc_version(str); } else { // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version() static char _gnu_libc_version[32]; jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version), "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release()); os::Linux::set_glibc_version(_gnu_libc_version); } n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0); if (n > 0) { char *str = (char *)malloc(n); confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n); // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells // us "NPTL-0.29" even we are running with LinuxThreads. Check if this // is the case. LinuxThreads has a hard limit on max number of threads. // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value. // On the other hand, NPTL does not have such a limit, sysconf() // will return -1 and errno is not changed. Check if it is really NPTL. if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 && strstr(str, "NPTL") && sysconf(_SC_THREAD_THREADS_MAX) > 0) { free(str); os::Linux::set_libpthread_version("linuxthreads"); } else { os::Linux::set_libpthread_version(str); } } else { // glibc before 2.3.2 only has LinuxThreads. os::Linux::set_libpthread_version("linuxthreads"); } if (strstr(libpthread_version(), "NPTL")) { os::Linux::set_is_NPTL(); } else { os::Linux::set_is_LinuxThreads(); } // LinuxThreads have two flavors: floating-stack mode, which allows variable // stack size; and fixed-stack mode. NPTL is always floating-stack. if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) { os::Linux::set_is_floating_stack(); } } ///////////////////////////////////////////////////////////////////////////// // thread stack // Force Linux kernel to expand current thread stack. If "bottom" is close // to the stack guard, caller should block all signals. // // MAP_GROWSDOWN: // A special mmap() flag that is used to implement thread stacks. It tells // kernel that the memory region should extend downwards when needed. This // allows early versions of LinuxThreads to only mmap the first few pages // when creating a new thread. Linux kernel will automatically expand thread // stack as needed (on page faults). // // However, because the memory region of a MAP_GROWSDOWN stack can grow on // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN // region, it's hard to tell if the fault is due to a legitimate stack // access or because of reading/writing non-exist memory (e.g. buffer // overrun). As a rule, if the fault happens below current stack pointer, // Linux kernel does not expand stack, instead a SIGSEGV is sent to the // application (see Linux kernel fault.c). // // This Linux feature can cause SIGSEGV when VM bangs thread stack for // stack overflow detection. // // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do // not use this flag. However, the stack of initial thread is not created // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though // unlikely) that user code can create a thread with MAP_GROWSDOWN stack // and then attach the thread to JVM. // // To get around the problem and allow stack banging on Linux, we need to // manually expand thread stack after receiving the SIGSEGV. // // There are two ways to expand thread stack to address "bottom", we used // both of them in JVM before 1.5: // 1. adjust stack pointer first so that it is below "bottom", and then // touch "bottom" // 2. mmap() the page in question // // Now alternate signal stack is gone, it's harder to use 2. For instance, // if current sp is already near the lower end of page 101, and we need to // call mmap() to map page 100, it is possible that part of the mmap() frame // will be placed in page 100. When page 100 is mapped, it is zero-filled. // That will destroy the mmap() frame and cause VM to crash. // // The following code works by adjusting sp first, then accessing the "bottom" // page to force a page fault. Linux kernel will then automatically expand the // stack mapping. // // _expand_stack_to() assumes its frame size is less than page size, which // should always be true if the function is not inlined. #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute #define NOINLINE #else #define NOINLINE __attribute__ ((noinline)) #endif static void _expand_stack_to(address bottom) NOINLINE; static void _expand_stack_to(address bottom) { address sp; size_t size; volatile char *p; // Adjust bottom to point to the largest address within the same page, it // gives us a one-page buffer if alloca() allocates slightly more memory. bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size()); bottom += os::Linux::page_size() - 1; // sp might be slightly above current stack pointer; if that's the case, we // will alloca() a little more space than necessary, which is OK. Don't use // os::current_stack_pointer(), as its result can be slightly below current // stack pointer, causing us to not alloca enough to reach "bottom". sp = (address)&sp; if (sp > bottom) { size = sp - bottom; p = (volatile char *)alloca(size); assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?"); p[0] = '\0'; } } bool os::Linux::manually_expand_stack(JavaThread * t, address addr) { assert(t!=NULL, "just checking"); assert(t->osthread()->expanding_stack(), "expand should be set"); assert(t->stack_base() != NULL, "stack_base was not initialized"); if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) { sigset_t mask_all, old_sigset; sigfillset(&mask_all); pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset); _expand_stack_to(addr); pthread_sigmask(SIG_SETMASK, &old_sigset, NULL); return true; } return false; } ////////////////////////////////////////////////////////////////////////////// // create new thread static address highest_vm_reserved_address(); // check if it's safe to start a new thread static bool _thread_safety_check(Thread* thread) { if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) { // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat) // Heap is mmap'ed at lower end of memory space. Thread stacks are // allocated (MAP_FIXED) from high address space. Every thread stack // occupies a fixed size slot (usually 2Mbytes, but user can change // it to other values if they rebuild LinuxThreads). // // Problem with MAP_FIXED is that mmap() can still succeed even part of // the memory region has already been mmap'ed. That means if we have too // many threads and/or very large heap, eventually thread stack will // collide with heap. // // Here we try to prevent heap/stack collision by comparing current // stack bottom with the highest address that has been mmap'ed by JVM // plus a safety margin for memory maps created by native code. // // This feature can be disabled by setting ThreadSafetyMargin to 0 // if (ThreadSafetyMargin > 0) { address stack_bottom = os::current_stack_base() - os::current_stack_size(); // not safe if our stack extends below the safety margin return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address(); } else { return true; } } else { // Floating stack LinuxThreads or NPTL: // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When // there's not enough space left, pthread_create() will fail. If we come // here, that means enough space has been reserved for stack. return true; } } // 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 LinuxThreads 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; } // thread_id is kernel thread id (similar to Solaris LWP id) osthread->set_thread_id(os::Linux::gettid()); if (UseNUMA) { int lgrp_id = os::numa_get_group_id(); if (lgrp_id != -1) { thread->set_lgrp_id(lgrp_id); } } // initialize signal mask for this thread os::Linux::hotspot_sigmask(thread); // initialize floating point control register os::Linux::init_thread_fpu_state(); // 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::Linux::supports_variable_stack_size()) { // calculate stack size if it's not specified by caller if (stack_size == 0) { stack_size = os::Linux::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 if (JavaThread::stack_size_at_create() > 0) 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::Linux::min_stack_allowed); pthread_attr_setstacksize(&attr, stack_size); } else { // let pthread_create() pick the default value. } // glibc guard page pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type)); ThreadState state; { // Serialize thread creation if we are running with fixed stack LinuxThreads bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack(); if (lock) { os::Linux::createThread_lock()->lock_without_safepoint_check(); } 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; if (lock) os::Linux::createThread_lock()->unlock(); 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); } } if (lock) { os::Linux::createThread_lock()->unlock(); } } // 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::Linux::_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; } // Store pthread info into the OSThread osthread->set_thread_id(os::Linux::gettid()); osthread->set_pthread_id(::pthread_self()); // initialize floating point control register os::Linux::init_thread_fpu_state(); // Initial thread state is RUNNABLE osthread->set_state(RUNNABLE); thread->set_osthread(osthread); if (UseNUMA) { int lgrp_id = os::numa_get_group_id(); if (lgrp_id != -1) { thread->set_lgrp_id(lgrp_id); } } if (os::Linux::is_initial_thread()) { // If current thread is initial thread, its stack is mapped on demand, // see notes about MAP_GROWSDOWN. Here we try to force kernel to map // the entire stack region to avoid SEGV in stack banging. // It is also useful to get around the heap-stack-gap problem on SuSE // kernel (see 4821821 for details). We first expand stack to the top // of yellow zone, then enable stack yellow zone (order is significant, // enabling yellow zone first will crash JVM on SuSE Linux), so there // is no gap between the last two virtual memory regions. JavaThread *jt = (JavaThread *)thread; address addr = jt->stack_yellow_zone_base(); assert(addr != NULL, "initialization problem?"); assert(jt->stack_available(addr) > 0, "stack guard should not be enabled"); osthread->set_expanding_stack(); os::Linux::manually_expand_stack(jt, addr); osthread->clear_expanding_stack(); } // initialize signal mask for this thread // and save the caller's signal mask os::Linux::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 Linux 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 int os::allocate_thread_local_storage() { pthread_key_t key; int rslt = pthread_key_create(&key, NULL); 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(); } ////////////////////////////////////////////////////////////////////////////// // initial thread // Check if current thread is the initial thread, similar to Solaris thr_main. bool os::Linux::is_initial_thread(void) { char dummy; // If called before init complete, thread stack bottom will be null. // Can be called if fatal error occurs before initialization. if (initial_thread_stack_bottom() == NULL) return false; assert(initial_thread_stack_bottom() != NULL && initial_thread_stack_size() != 0, "os::init did not locate initial thread's stack region"); if ((address)&dummy >= initial_thread_stack_bottom() && (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) return true; else return false; } // Find the virtual memory area that contains addr static bool find_vma(address addr, address* vma_low, address* vma_high) { FILE *fp = fopen("/proc/self/maps", "r"); if (fp) { address low, high; while (!feof(fp)) { if (fscanf(fp, "%p-%p", &low, &high) == 2) { if (low <= addr && addr < high) { if (vma_low) *vma_low = low; if (vma_high) *vma_high = high; fclose (fp); return true; } } for (;;) { int ch = fgetc(fp); if (ch == EOF || ch == (int)'\n') break; } } fclose(fp); } return false; } // Locate initial thread stack. This special handling of initial thread stack // is needed because pthread_getattr_np() on most (all?) Linux distros returns // bogus value for initial thread. void os::Linux::capture_initial_stack(size_t max_size) { // stack size is the easy part, get it from RLIMIT_STACK size_t stack_size; struct rlimit rlim; getrlimit(RLIMIT_STACK, &rlim); stack_size = rlim.rlim_cur; // 6308388: a bug in ld.so will relocate its own .data section to the // lower end of primordial stack; reduce ulimit -s value a little bit // so we won't install guard page on ld.so's data section. stack_size -= 2 * page_size(); // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat // 7.1, in both cases we will get 2G in return value. // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0, // SuSE 7.2, Debian) can not handle alternate signal stack correctly // for initial thread if its stack size exceeds 6M. Cap it at 2M, // in case other parts in glibc still assumes 2M max stack size. // FIXME: alt signal stack is gone, maybe we can relax this constraint? #ifndef IA64 if (stack_size > 2 * K * K) stack_size = 2 * K * K; #else // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small if (stack_size > 4 * K * K) stack_size = 4 * K * K; #endif // Try to figure out where the stack base (top) is. This is harder. // // When an application is started, glibc saves the initial stack pointer in // a global variable "__libc_stack_end", which is then used by system // libraries. __libc_stack_end should be pretty close to stack top. The // variable is available since the very early days. However, because it is // a private interface, it could disappear in the future. // // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar // to __libc_stack_end, it is very close to stack top, but isn't the real // stack top. Note that /proc may not exist if VM is running as a chroot // program, so reading /proc/<pid>/stat could fail. Also the contents of // /proc/<pid>/stat could change in the future (though unlikely). // // We try __libc_stack_end first. If that doesn't work, look for // /proc/<pid>/stat. If neither of them works, we use current stack pointer // as a hint, which should work well in most cases. uintptr_t stack_start; // try __libc_stack_end first uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end"); if (p && *p) { stack_start = *p; } else { // see if we can get the start_stack field from /proc/self/stat FILE *fp; int pid; char state; int ppid; int pgrp; int session; int nr; int tpgrp; unsigned long flags; unsigned long minflt; unsigned long cminflt; unsigned long majflt; unsigned long cmajflt; unsigned long utime; unsigned long stime; long cutime; long cstime; long prio; long nice; long junk; long it_real; uintptr_t start; uintptr_t vsize; uintptr_t rss; unsigned long rsslim; uintptr_t scodes; uintptr_t ecode; int i; // Figure what the primordial thread stack base is. Code is inspired // by email from Hans Boehm. /proc/self/stat begins with current pid, // followed by command name surrounded by parentheses, state, etc. char stat[2048]; int statlen; fp = fopen("/proc/self/stat", "r"); if (fp) { statlen = fread(stat, 1, 2047, fp); stat[statlen] = '\0'; fclose(fp); // Skip pid and the command string. Note that we could be dealing with // weird command names, e.g. user could decide to rename java launcher // to "java 1.4.2 :)", then the stat file would look like // 1234 (java 1.4.2 :)) R ... ... // We don't really need to know the command string, just find the last // occurrence of ")" and then start parsing from there. See bug 4726580. char * s = strrchr(stat, ')'); i = 0; if (s) { // Skip blank chars do s++; while (isspace(*s)); /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */ /* 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 */ i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld " UINTX_FORMAT UINTX_FORMAT UINTX_FORMAT " %lu " UINTX_FORMAT UINTX_FORMAT UINTX_FORMAT, &state, /* 3 %c */ &ppid, /* 4 %d */ &pgrp, /* 5 %d */ &session, /* 6 %d */ &nr, /* 7 %d */ &tpgrp, /* 8 %d */ &flags, /* 9 %lu */ &minflt, /* 10 %lu */ &cminflt, /* 11 %lu */ &majflt, /* 12 %lu */ &cmajflt, /* 13 %lu */ &utime, /* 14 %lu */ &stime, /* 15 %lu */ &cutime, /* 16 %ld */ &cstime, /* 17 %ld */ &prio, /* 18 %ld */ &nice, /* 19 %ld */ &junk, /* 20 %ld */ &it_real, /* 21 %ld */ &start, /* 22 UINTX_FORMAT */ &vsize, /* 23 UINTX_FORMAT */ &rss, /* 24 UINTX_FORMAT */ &rsslim, /* 25 %lu */ &scodes, /* 26 UINTX_FORMAT */ &ecode, /* 27 UINTX_FORMAT */ &stack_start); /* 28 UINTX_FORMAT */ } if (i != 28 - 2) { assert(false, "Bad conversion from /proc/self/stat"); // product mode - assume we are the initial thread, good luck in the // embedded case. warning("Can't detect initial thread stack location - bad conversion"); stack_start = (uintptr_t) &rlim; } } else { // For some reason we can't open /proc/self/stat (for example, running on // FreeBSD with a Linux emulator, or inside chroot), this should work for // most cases, so don't abort: warning("Can't detect initial thread stack location - no /proc/self/stat"); stack_start = (uintptr_t) &rlim; } } // Now we have a pointer (stack_start) very close to the stack top, the // next thing to do is to figure out the exact location of stack top. We // can find out the virtual memory area that contains stack_start by // reading /proc/self/maps, it should be the last vma in /proc/self/maps, // and its upper limit is the real stack top. (again, this would fail if // running inside chroot, because /proc may not exist.) uintptr_t stack_top; address low, high; if (find_vma((address)stack_start, &low, &high)) { // success, "high" is the true stack top. (ignore "low", because initial // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.) stack_top = (uintptr_t)high; } else { // failed, likely because /proc/self/maps does not exist warning("Can't detect initial thread stack location - find_vma failed"); // best effort: stack_start is normally within a few pages below the real // stack top, use it as stack top, and reduce stack size so we won't put // guard page outside stack. stack_top = stack_start; stack_size -= 16 * page_size(); } // stack_top could be partially down the page so align it stack_top = align_size_up(stack_top, page_size()); if (max_size && stack_size > max_size) { _initial_thread_stack_size = max_size; } else { _initial_thread_stack_size = stack_size; } _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size()); _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size; } //////////////////////////////////////////////////////////////////////////////// // 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()) * 0.000001; } jlong os::elapsed_counter() { timeval time; int status = gettimeofday(&time, NULL); return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count; } jlong os::elapsed_frequency() { return (1000 * 1000); } // For now, we say that linux does not support vtime. I have no idea // whether it can actually be made to (DLD, 9/13/05). bool os::supports_vtime() { return false; } 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, "linux error"); return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000); } #ifndef CLOCK_MONOTONIC #define CLOCK_MONOTONIC (1) #endif void os::Linux::clock_init() { // we do dlopen's in this particular order due to bug in linux // dynamical loader (see 6348968) leading to crash on exit void* handle = dlopen("librt.so.1", RTLD_LAZY); if (handle == NULL) { handle = dlopen("librt.so", RTLD_LAZY); } if (handle) { int (*clock_getres_func)(clockid_t, struct timespec*) = (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres"); int (*clock_gettime_func)(clockid_t, struct timespec*) = (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime"); if (clock_getres_func && clock_gettime_func) { // See if monotonic clock is supported by the kernel. Note that some // early implementations simply return kernel jiffies (updated every // 1/100 or 1/1000 second). It would be bad to use such a low res clock // for nano time (though the monotonic property is still nice to have). // It's fixed in newer kernels, however clock_getres() still returns // 1/HZ. We check if clock_getres() works, but will ignore its reported // resolution for now. Hopefully as people move to new kernels, this // won't be a problem. struct timespec res; struct timespec tp; if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 && clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) { // yes, monotonic clock is supported _clock_gettime = clock_gettime_func; } else { // close librt if there is no monotonic clock dlclose(handle); } } } } #ifndef SYS_clock_getres #if defined(IA32) || defined(AMD64) #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229) #else #error Value of SYS_clock_getres not known on this platform #endif #endif #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y) void os::Linux::fast_thread_clock_init() { if (!UseLinuxPosixThreadCPUClocks) { return; } clockid_t clockid; struct timespec tp; int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) = (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid"); // Switch to using fast clocks for thread cpu time if // the sys_clock_getres() returns 0 error code. // Note, that some kernels may support the current thread // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks // returned by the pthread_getcpuclockid(). // If the fast Posix clocks are supported then the sys_clock_getres() // must return at least tp.tv_sec == 0 which means a resolution // better than 1 sec. This is extra check for reliability. if(pthread_getcpuclockid_func && pthread_getcpuclockid_func(_main_thread, &clockid) == 0 && sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) { _supports_fast_thread_cpu_time = true; _pthread_getcpuclockid = pthread_getcpuclockid_func; } } jlong os::javaTimeNanos() { if (Linux::supports_monotonic_clock()) { struct timespec tp; int status = Linux::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, "linux error"); jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec); return 1000 * usecs; } } void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { if (Linux::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 LinuxThreads only kills current thread ::abort(); } // unused on linux for now. void os::set_error_file(const char *logfile) {} intx os::current_thread_id() { return (intx)pthread_self(); } int os::current_process_id() { // Under the old linux thread library, linux 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). Linux 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_linux.hpp file return (int)(_initial_pid ? _initial_pid : getpid()); } // DLL functions const char* os::dll_file_extension() { return ".so"; } const char* os::get_temp_directory() { const char *prop = Arguments::get_property("java.io.tmpdir"); return prop == NULL ? "/tmp" : prop; } static bool file_exists(const char* filename) { struct stat statbuf; if (filename == NULL || strlen(filename) == 0) { return false; } return os::stat(filename, &statbuf) == 0; } void os::dll_build_name(char* buffer, size_t buflen, const char* pname, const char* fname) { // Copied from libhpi const size_t pnamelen = pname ? strlen(pname) : 0; // Quietly truncate on buffer overflow. Should be an error. if (pnamelen + strlen(fname) + 10 > (size_t) buflen) { *buffer = '\0'; return; } if (pnamelen == 0) { snprintf(buffer, buflen, "lib%s.so", fname); } else if (strchr(pname, *os::path_separator()) != NULL) { int n; char** pelements = split_path(pname, &n); 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/lib%s.so", pelements[i], fname); if (file_exists(buffer)) { break; } } // release the storage for (int i = 0 ; i < n ; i++) { if (pelements[i] != NULL) { FREE_C_HEAP_ARRAY(char, pelements[i]); } } if (pelements != NULL) { FREE_C_HEAP_ARRAY(char*, pelements); } } else { snprintf(buffer, buflen, "%s/lib%s.so", pname, fname); } } const char* os::get_current_directory(char *buf, int buflen) { return getcwd(buf, buflen); } // check if addr is inside libjvm[_g].so bool os::address_is_in_vm(address addr) { static address libjvm_base_addr; Dl_info dlinfo; if (libjvm_base_addr == NULL) { dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo); libjvm_base_addr = (address)dlinfo.dli_fbase; assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm"); } if (dladdr((void *)addr, &dlinfo)) { if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true; } return false; } bool os::dll_address_to_function_name(address addr, char *buf, int buflen, int *offset) { Dl_info dlinfo; if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) { if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname); if (offset) *offset = addr - (address)dlinfo.dli_saddr; return true; } else { if (buf) buf[0] = '\0'; if (offset) *offset = -1; return false; } } struct _address_to_library_name { address addr; // input : memory address size_t buflen; // size of fname char* fname; // output: library name address base; // library base addr }; static int address_to_library_name_callback(struct dl_phdr_info *info, size_t size, void *data) { int i; bool found = false; address libbase = NULL; struct _address_to_library_name * d = (struct _address_to_library_name *)data; // iterate through all loadable segments for (i = 0; i < info->dlpi_phnum; i++) { address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); if (info->dlpi_phdr[i].p_type == PT_LOAD) { // base address of a library is the lowest address of its loaded // segments. if (libbase == NULL || libbase > segbase) { libbase = segbase; } // see if 'addr' is within current segment if (segbase <= d->addr && d->addr < segbase + info->dlpi_phdr[i].p_memsz) { found = true; } } } // dlpi_name is NULL or empty if the ELF file is executable, return 0 // so dll_address_to_library_name() can fall through to use dladdr() which // can figure out executable name from argv[0]. if (found && info->dlpi_name && info->dlpi_name[0]) { d->base = libbase; if (d->fname) { jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name); } return 1; } return 0; } bool os::dll_address_to_library_name(address addr, char* buf, int buflen, int* offset) { Dl_info dlinfo; struct _address_to_library_name data; // There is a bug in old glibc dladdr() implementation that it could resolve // to wrong library name if the .so file has a base address != NULL. Here // we iterate through the program headers of all loaded libraries to find // out which library 'addr' really belongs to. This workaround can be // removed once the minimum requirement for glibc is moved to 2.3.x. data.addr = addr; data.fname = buf; data.buflen = buflen; data.base = NULL; int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data); if (rslt) { // buf already contains library name if (offset) *offset = addr - data.base; return true; } else if (dladdr((void*)addr, &dlinfo)){ if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname); if (offset) *offset = addr - (address)dlinfo.dli_fbase; return true; } else { if (buf) 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 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 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; } /* * glibc-2.0 libdl is not MT safe. If you are building with any glibc, * chances are you might want to run the generated bits against glibc-2.0 * libdl.so, so always use locking for any version of glibc. */ void* os::dll_lookup(void* handle, const char* name) { pthread_mutex_lock(&dl_mutex); void* res = dlsym(handle, name); pthread_mutex_unlock(&dl_mutex); return res; } 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:"); char fname[32]; pid_t pid = os::Linux::gettid(); jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid); if (!_print_ascii_file(fname, st)) { st->print("Can not get library information for pid = %d\n", pid); } } void os::print_os_info(outputStream* st) { st->print("OS:"); // Try to identify popular distros. // Most Linux distributions have /etc/XXX-release file, which contains // the OS version string. Some have more than one /etc/XXX-release file // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.), // so the order is important. if (!_print_ascii_file("/etc/mandrake-release", st) && !_print_ascii_file("/etc/sun-release", st) && !_print_ascii_file("/etc/redhat-release", st) && !_print_ascii_file("/etc/SuSE-release", st) && !_print_ascii_file("/etc/turbolinux-release", st) && !_print_ascii_file("/etc/gentoo-release", st) && !_print_ascii_file("/etc/debian_version", st)) { st->print("Linux"); } st->cr(); // kernel st->print("uname:"); struct utsname name; uname(&name); st->print(name.sysname); st->print(" "); st->print(name.release); st->print(" "); st->print(name.version); st->print(" "); st->print(name.machine); st->cr(); // Print warning if unsafe chroot environment detected if (unsafe_chroot_detected) { st->print("WARNING!! "); st->print_cr(unstable_chroot_error); } // libc, pthread st->print("libc:"); st->print(os::Linux::glibc_version()); st->print(" "); st->print(os::Linux::libpthread_version()); st->print(" "); if (os::Linux::is_LinuxThreads()) { st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed"); } st->cr(); // rlimit st->print("rlimit:"); struct rlimit rlim; st->print(" STACK "); getrlimit(RLIMIT_STACK, &rlim); if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); else st->print("%uk", rlim.rlim_cur >> 10); st->print(", CORE "); getrlimit(RLIMIT_CORE, &rlim); if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); else st->print("%uk", rlim.rlim_cur >> 10); st->print(", NPROC "); getrlimit(RLIMIT_NPROC, &rlim); if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); else st->print("%d", rlim.rlim_cur); st->print(", NOFILE "); getrlimit(RLIMIT_NOFILE, &rlim); if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); else st->print("%d", rlim.rlim_cur); st->print(", AS "); getrlimit(RLIMIT_AS, &rlim); if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity"); else st->print("%uk", rlim.rlim_cur >> 10); st->cr(); // load average st->print("load average:"); double loadavg[3]; os::loadavg(loadavg, 3); st->print("%0.02f %0.02f %0.02f", loadavg[0], loadavg[1], loadavg[2]); st->cr(); } void os::print_memory_info(outputStream* st) { st->print("Memory:"); st->print(" %dk page", os::vm_page_size()>>10); // values in struct sysinfo are "unsigned long" struct sysinfo si; sysinfo(&si); st->print(", physical " UINT64_FORMAT "k", os::physical_memory() >> 10); st->print("(" UINT64_FORMAT "k free)", os::available_memory() >> 10); st->print(", swap " UINT64_FORMAT "k", ((jlong)si.totalswap * si.mem_unit) >> 10); st->print("(" UINT64_FORMAT "k free)", ((jlong)si.freeswap * si.mem_unit) >> 10); st->cr(); } // Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific // but they're the same for all the linux arch that we support // and they're the same for solaris but there's no common place to put this. const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR", "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG", "ILL_COPROC", "ILL_BADSTK" }; const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV", "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES", "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" }; const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" }; const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" }; void os::print_siginfo(outputStream* st, void* siginfo) { st->print("siginfo:"); const int buflen = 100; char buf[buflen]; siginfo_t *si = (siginfo_t*)siginfo; st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen)); if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) { st->print("si_errno=%s", buf); } else { st->print("si_errno=%d", si->si_errno); } const int c = si->si_code; assert(c > 0, "unexpected si_code"); switch (si->si_signo) { case SIGILL: st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]); st->print(", si_addr=" PTR_FORMAT, si->si_addr); break; case SIGFPE: st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]); st->print(", si_addr=" PTR_FORMAT, si->si_addr); break; case SIGSEGV: st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]); st->print(", si_addr=" PTR_FORMAT, si->si_addr); break; case SIGBUS: st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]); st->print(", si_addr=" PTR_FORMAT, si->si_addr); break; default: st->print(", si_code=%d", si->si_code); // no si_addr } if ((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.so or libjvm_g.so void os::jvm_path(char *buf, jint len) { // Error checking. if (len < 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 != 0, "cannot locate libjvm"); if (realpath(dli_fname, buf) == NULL) return; if (strcmp(Arguments::sun_java_launcher(), "gamma") == 0) { // Support for the gamma launcher. Typical value for buf is // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". 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 fix // up the path so it looks like libjvm.so is installed there (append a // fake suffix hotspot/libjvm.so). 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) { // Check the current module name "libjvm.so" or "libjvm_g.so". p = strrchr(buf, '/'); assert(strstr(p, "/libjvm") == p, "invalid library name"); p = strstr(p, "_g") ? "_g" : ""; if (realpath(java_home_var, buf) == NULL) return; sprintf(buf + strlen(buf), "/jre/lib/%s", cpu_arch); if (0 == access(buf, F_OK)) { // Use current module name "libjvm[_g].so" instead of // "libjvm"debug_only("_g")".so" since for fastdebug version // we should have "libjvm.so" but debug_only("_g") adds "_g"! // It is used when we are choosing the HPI library's name // "libhpi[_g].so" in hpi::initialize_get_interface(). sprintf(buf + strlen(buf), "/hotspot/libjvm%s.so", p); } else { // Go back to path of .so if (realpath(dli_fname, buf) == NULL) return; } } } } strcpy(saved_jvm_path, buf); } 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 }; // Linux(POSIX) specific hand shaking semaphore. static sem_t sig_sem; void os::signal_init_pd() { // Initialize signal structures ::memset((void*)pending_signals, 0, sizeof(pending_signals)); // Initialize signal semaphore ::sem_init(&sig_sem, 0, 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::Linux::page_size() != -1, "must call os::init"); return os::Linux::page_size(); } // Solaris allocates memory by pages. int os::vm_allocation_granularity() { assert(os::Linux::page_size() != -1, "must call os::init"); return os::Linux::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 linux_wrap_code(char* base, size_t size) { static volatile jint cnt = 0; if (!UseOprofile) { return; } char buf[40]; int num = Atomic::add(1, &cnt); snprintf(buf, sizeof(buf), "%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); } } // NOTE: Linux 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::commit_memory(char* addr, size_t size, bool exec) { int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE; uintptr_t res = (uintptr_t) ::mmap(addr, size, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); return res != (uintptr_t) MAP_FAILED; } bool os::commit_memory(char* addr, size_t size, size_t alignment_hint, bool exec) { return commit_memory(addr, size, exec); } void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) { } void os::free_memory(char *addr, size_t bytes) { ::mmap(addr, bytes, PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0); } void os::numa_make_global(char *addr, size_t bytes) { Linux::numa_interleave_memory(addr, bytes); } void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) { Linux::numa_tonode_memory(addr, bytes, lgrp_hint); } bool os::numa_topology_changed() { return false; } size_t os::numa_get_groups_num() { int max_node = Linux::numa_max_node(); return max_node > 0 ? max_node + 1 : 1; } int os::numa_get_group_id() { int cpu_id = Linux::sched_getcpu(); if (cpu_id != -1) { int lgrp_id = Linux::get_node_by_cpu(cpu_id); if (lgrp_id != -1) { return lgrp_id; } } return 0; } size_t os::numa_get_leaf_groups(int *ids, size_t size) { for (size_t i = 0; i < size; i++) { ids[i] = i; } return size; } 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; } extern "C" void numa_warn(int number, char *where, ...) { } extern "C" void numa_error(char *where) { } // If we are running with libnuma version > 2, then we should // be trying to use symbols with versions 1.1 // If we are running with earlier version, which did not have symbol versions, // we should use the base version. void* os::Linux::libnuma_dlsym(void* handle, const char *name) { void *f = dlvsym(handle, name, "libnuma_1.1"); if (f == NULL) { f = dlsym(handle, name); } return f; } bool os::Linux::libnuma_init() { // sched_getcpu() should be in libc. set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, dlsym(RTLD_DEFAULT, "sched_getcpu"))); if (sched_getcpu() != -1) { // Does it work? void *handle = dlopen("libnuma.so.1", RTLD_LAZY); if (handle != NULL) { set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t, libnuma_dlsym(handle, "numa_node_to_cpus"))); set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t, libnuma_dlsym(handle, "numa_max_node"))); set_numa_available(CAST_TO_FN_PTR(numa_available_func_t, libnuma_dlsym(handle, "numa_available"))); set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t, libnuma_dlsym(handle, "numa_tonode_memory"))); set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t, libnuma_dlsym(handle, "numa_interleave_memory"))); if (numa_available() != -1) { set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes")); // Create a cpu -> node mapping _cpu_to_node = new (ResourceObj::C_HEAP) GrowableArray<int>(0, true); rebuild_cpu_to_node_map(); return true; } } } return false; } // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id. // The table is later used in get_node_by_cpu(). void os::Linux::rebuild_cpu_to_node_map() { const size_t NCPUS = 32768; // Since the buffer size computation is very obscure // in libnuma (possible values are starting from 16, // and continuing up with every other power of 2, but less // than the maximum number of CPUs supported by kernel), and // is a subject to change (in libnuma version 2 the requirements // are more reasonable) we'll just hardcode the number they use // in the library. const size_t BitsPerCLong = sizeof(long) * CHAR_BIT; size_t cpu_num = os::active_processor_count(); size_t cpu_map_size = NCPUS / BitsPerCLong; size_t cpu_map_valid_size = MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size); cpu_to_node()->clear(); cpu_to_node()->at_grow(cpu_num - 1); size_t node_num = numa_get_groups_num(); unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size); for (size_t i = 0; i < node_num; i++) { if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) { for (size_t j = 0; j < cpu_map_valid_size; j++) { if (cpu_map[j] != 0) { for (size_t k = 0; k < BitsPerCLong; k++) { if (cpu_map[j] & (1UL << k)) { cpu_to_node()->at_put(j * BitsPerCLong + k, i); } } } } } } FREE_C_HEAP_ARRAY(unsigned long, cpu_map); } int os::Linux::get_node_by_cpu(int cpu_id) { if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) { return cpu_to_node()->at(cpu_id); } return -1; } GrowableArray<int>* os::Linux::_cpu_to_node; os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu; os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus; os::Linux::numa_max_node_func_t os::Linux::_numa_max_node; os::Linux::numa_available_func_t os::Linux::_numa_available; os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory; os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory; unsigned long* os::Linux::_numa_all_nodes; bool os::uncommit_memory(char* addr, size_t size) { return ::mmap(addr, size, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0) != MAP_FAILED; } // Linux uses a growable mapping for the stack, and if the mapping for // the stack guard pages is not removed when we detach a thread the // stack cannot grow beyond the pages where the stack guard was // mapped. If at some point later in the process the stack expands to // that point, the Linux kernel cannot expand the stack any further // because the guard pages are in the way, and a segfault occurs. // // However, it's essential not to split the stack region by unmapping // a region (leaving a hole) that's already part of the stack mapping, // so if the stack mapping has already grown beyond the guard pages at // the time we create them, we have to truncate the stack mapping. // So, we need to know the extent of the stack mapping when // create_stack_guard_pages() is called. // Find the bounds of the stack mapping. Return true for success. // // We only need this for stacks that are growable: at the time of // writing thread stacks don't use growable mappings (i.e. those // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this // only applies to the main thread. static bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) { FILE *f = fopen("/proc/self/maps", "r"); if (f == NULL) return false; while (!feof(f)) { size_t dummy; char *str = NULL; ssize_t len = getline(&str, &dummy, f); if (len == -1) { fclose(f); return false; } if (len > 0 && str[len-1] == '\n') { str[len-1] = 0; len--; } static const char *stack_str = "[stack]"; if (len > (ssize_t)strlen(stack_str) && (strcmp(str + len - strlen(stack_str), stack_str) == 0)) { if (sscanf(str, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) { uintptr_t sp = (uintptr_t)__builtin_frame_address(0); if (sp >= *bottom && sp <= *top) { free(str); fclose(f); return true; } } } free(str); } fclose(f); return false; } // If the (growable) stack mapping already extends beyond the point // where we're going to put our guard pages, truncate the mapping at // that point by munmap()ping it. This ensures that when we later // munmap() the guard pages we don't leave a hole in the stack // mapping. bool os::create_stack_guard_pages(char* addr, size_t size) { uintptr_t stack_extent, stack_base; if (get_stack_bounds(&stack_extent, &stack_base)) { if (stack_extent < (uintptr_t)addr) ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent); } return os::commit_memory(addr, size); } // 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) { uintptr_t stack_extent, stack_base; if (get_stack_bounds(&stack_extent, &stack_base)) { return ::munmap(addr, size) == 0; } 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 Linux 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::Linux::page_size() == 0, "unaligned address"); flags |= MAP_FIXED; } // Map uncommitted pages PROT_READ and PROT_WRITE, change access // to PROT_EXEC if executable when we commit the page. addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE, 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::reserve_memory(size_t bytes, char* requested_addr, size_t alignment_hint) { return anon_mmap(requested_addr, bytes, (requested_addr != NULL)); } bool os::release_memory(char* addr, size_t size) { return anon_munmap(addr, size); } static address highest_vm_reserved_address() { return _highest_vm_reserved_address; } static bool linux_mprotect(char* addr, size_t size, int prot) { // Linux wants the mprotect address argument to be page aligned. char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::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::Linux::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 linux_mprotect(addr, bytes, p); } bool os::guard_memory(char* addr, size_t size) { return linux_mprotect(addr, size, PROT_NONE); } bool os::unguard_memory(char* addr, size_t size) { return linux_mprotect(addr, size, PROT_READ|PROT_WRITE); } // Large page support static size_t _large_page_size = 0; bool os::large_page_init() { if (!UseLargePages) return false; if (LargePageSizeInBytes) { _large_page_size = LargePageSizeInBytes; } else { // large_page_size on Linux is used to round up heap size. x86 uses either // 2M or 4M page, depending on whether PAE (Physical Address Extensions) // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use // page as large as 256M. // // Here we try to figure out page size by parsing /proc/meminfo and looking // for a line with the following format: // Hugepagesize: 2048 kB // // If we can't determine the value (e.g. /proc is not mounted, or the text // format has been changed), we'll use the largest page size supported by // the processor. #ifndef ZERO _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M); #endif // ZERO FILE *fp = fopen("/proc/meminfo", "r"); if (fp) { while (!feof(fp)) { int x = 0; char buf[16]; if (fscanf(fp, "Hugepagesize: %d", &x) == 1) { if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) { _large_page_size = x * K; break; } } else { // skip to next line for (;;) { int ch = fgetc(fp); if (ch == EOF || ch == (int)'\n') break; } } } fclose(fp); } } const size_t default_page_size = (size_t)Linux::page_size(); if (_large_page_size > default_page_size) { _page_sizes[0] = _large_page_size; _page_sizes[1] = default_page_size; _page_sizes[2] = 0; } // Large page support is available on 2.6 or newer kernel, some vendors // (e.g. Redhat) have backported it to their 2.4 based distributions. // We optimistically assume the support is available. If later it turns out // not true, VM will automatically switch to use regular page size. return true; } #ifndef SHM_HUGETLB #define SHM_HUGETLB 04000 #endif char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) { // "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, "only for large pages"); key_t key = IPC_PRIVATE; char *addr; bool warn_on_failure = UseLargePages && (!FLAG_IS_DEFAULT(UseLargePages) || !FLAG_IS_DEFAULT(LargePageSizeInBytes) ); char msg[128]; // 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, SHM_HUGETLB|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 Linux 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) { jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno); warning(msg); } return NULL; } // attach to the region addr = (char*)shmat(shmid, NULL, 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) { jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err); warning(msg); } return NULL; } return addr; } bool os::release_memory_special(char* base, size_t bytes) { // detaching the SHM segment will also delete it, see reserve_memory_special() int rslt = shmdt(base); return rslt == 0; } size_t os::large_page_size() { return _large_page_size; } // Linux does not support anonymous mmap with large page memory. The only way // to reserve large page memory without file backing is through SysV shared // memory API. The entire memory region is committed and pinned upfront. // Hopefully this will change in the future... bool os::can_commit_large_page_memory() { return false; } bool os::can_execute_large_page_memory() { return false; } // Reserve memory at an arbitrary address, only if that area is // available (and not reserved for something else). char* os::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 LinuxThreads. 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; // Linux 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) { return ::read(fd, buf, nBytes); } // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation. // Solaris uses poll(), linux 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. const int NANOSECS_PER_MILLISECS = 1000000; 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(!Linux::supports_monotonic_clock(), "time moving backwards"); } else { millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS; } 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(!Linux::supports_monotonic_clock(), "time moving backwards"); } else { millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS; } if(millis <= 0) break ; prevtime = newtime; slp->park(millis); } return OS_OK ; } } int os::naked_sleep() { // %% make the sleep time an integer flag. for now use 1 millisec. return os::sleep(Thread::current(), 1, false); } // 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 Linux 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 Linux applications are run with SCHED_OTHER policy. SCHED_OTHER // only supports dynamic priority, static priority must be zero. For real-time // applications, Linux 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. int os::java_to_os_priority[MaxPriority + 1] = { 19, // 0 Entry should never be used 4, // 1 MinPriority 3, // 2 2, // 3 1, // 4 0, // 5 NormPriority -1, // 6 -2, // 7 -3, // 8 -4, // 9 NearMaxPriority -5 // 10 MaxPriority }; 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 Linux"); } ThreadPriorityPolicy = 0; } } return 0; } OSReturn os::set_native_priority(Thread* thread, int newpri) { if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK; int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri); return (ret == 0) ? OS_OK : OS_ERR; } 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; *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id()); 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); // notify the suspend action is completed, we have now resumed osthread->sr.clear_suspended(); } 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 // 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(), "Must be VMThread"); // read current suspend action int action = osthread->sr.suspend_action(); if (action == SR_SUSPEND) { suspend_save_context(osthread, siginfo, context); // Notify the suspend action is about to be completed. do_suspend() // waits until SR_SUSPENDED is set and then returns. We will wait // here for a resume signal and that completes the suspend-other // action. do_suspend/do_resume is always called as a pair from // the same thread - so there are no races // notify the caller osthread->sr.set_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); // wait here until we are resumed do { sigsuspend(&suspend_set); // ignore all returns until we get a resume signal } while (osthread->sr.suspend_action() != SR_CONTINUE); resume_clear_context(osthread); } else { assert(action == SR_CONTINUE, "unexpected sr action"); // nothing special to do - just leave the handler } 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 Linux platforms). Note that LinuxThreads 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::Linux::set_our_sigflags(SR_signum, act.sa_flags); return 0; } static int SR_finalize() { return 0; } // 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) { // mark as suspended and send signal osthread->sr.set_suspend_action(SR_SUSPEND); int status = pthread_kill(osthread->pthread_id(), SR_signum); assert_status(status == 0, status, "pthread_kill"); // check status and wait until notified of suspension if (status == 0) { for (int i = 0; !osthread->sr.is_suspended(); i++) { os::yield_all(i); } osthread->sr.set_suspend_action(SR_NONE); return true; } else { osthread->sr.set_suspend_action(SR_NONE); return false; } } static void do_resume(OSThread* osthread) { assert(osthread->sr.is_suspended(), "thread should be suspended"); osthread->sr.set_suspend_action(SR_CONTINUE); int status = pthread_kill(osthread->pthread_id(), SR_signum); assert_status(status == 0, status, "pthread_kill"); // check status and wait unit notified of resumption if (status == 0) { for (int i = 0; osthread->sr.is_suspended(); i++) { os::yield_all(i); } } osthread->sr.set_suspend_action(SR_NONE); } //////////////////////////////////////////////////////////////////////////////// // 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" int JVM_handle_linux_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"); JVM_handle_linux_signal(sig, info, uc, true); } // This boolean allows users to forward their own non-matching signals // to JVM_handle_linux_signal, harmlessly. bool os::Linux::signal_handlers_are_installed = false; // For signal-chaining struct sigaction os::Linux::sigact[MAXSIGNUM]; unsigned int os::Linux::sigs = 0; bool os::Linux::libjsig_is_loaded = false; typedef struct sigaction *(*get_signal_t)(int); get_signal_t os::Linux::get_signal_action = NULL; struct sigaction* os::Linux::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::Linux::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::Linux::get_preinstalled_handler(int sig) { if ((( (unsigned int)1 << sig ) & sigs) != 0) { return &sigact[sig]; } return NULL; } void os::Linux::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::Linux::sigflags[MAXSIGNUM]; int os::Linux::get_our_sigflags(int sig) { assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); return sigflags[sig]; } void os::Linux::set_our_sigflags(int sig, int flags) { assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range"); sigflags[sig] = flags; } void os::Linux::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 { fatal2("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; } // 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::Linux::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 (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) { tty->print_cr("Info: libjsig is activated, all active signal checking is disabled"); check_signals = false; } if (AllowUserSignalHandlers) { tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled"); check_signals = false; } } } } // This is the fastest way to get thread cpu time on Linux. // Returns cpu time (user+sys) for any thread, not only for current. // POSIX compliant clocks are implemented in the kernels 2.6.16+. // It might work on 2.6.10+ with a special kernel/glibc patch. // For reference, please, see IEEE Std 1003.1-2004: // http://www.unix.org/single_unix_specification jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) { struct timespec tp; int rc = os::Linux::clock_gettime(clockid, &tp); assert(rc == 0, "clock_gettime is expected to return 0 code"); return (tp.tv_sec * SEC_IN_NANOSECS) + tp.tv_nsec; } ///// // glibc on Linux 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]=" PTR32_FORMAT, *(uint32_t*)&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=" PTR32_FORMAT, 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::Linux::get_our_sigflags(sig)) { st->print( ", flags was changed from " PTR32_FORMAT ", consider using jsig library", os::Linux::get_our_sigflags(sig)); } } st->cr(); } #define DO_SIGNAL_CHECK(sig) \ if (!sigismember(&check_signal_done, sig)) \ os::Linux::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::Linux::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); } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) { tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN)); tty->print("expected:" PTR32_FORMAT, os::Linux::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 LinuxThreads the JavaMain thread pid (primordial thread) // is different than the pid of the java launcher thread. // So, on Linux, 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 = sysconf(_SC_CLK_TCK); init_random(1234567); ThreadCritical::initialize(); Linux::set_page_size(sysconf(_SC_PAGESIZE)); if (Linux::page_size() == -1) { fatal1("os_linux.cpp: os::init: sysconf failed (%s)", strerror(errno)); } init_page_sizes((size_t) Linux::page_size()); Linux::initialize_system_info(); // main_thread points to the aboriginal thread Linux::_main_thread = pthread_self(); Linux::clock_init(); initial_time_count = os::elapsed_counter(); pthread_mutex_init(&dl_mutex, NULL); } // 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) { Linux::fast_thread_clock_init(); // Allocate a single page and mark it as readable for safepoint polling address polling_page = (address) ::mmap(NULL, Linux::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, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); guarantee( mem_serialize_page != NULL, "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 } FLAG_SET_DEFAULT(UseLargePages, os::large_page_init()); // initialize suspend/resume support - must do this before signal_sets_init() if (SR_initialize() != 0) { perror("SR_initialize failed"); return JNI_ERR; } Linux::signal_sets_init(); Linux::install_signal_handlers(); size_t threadStackSizeInBytes = ThreadStackSize * K; if (threadStackSizeInBytes != 0 && threadStackSizeInBytes < Linux::min_stack_allowed) { tty->print_cr("\nThe stack size specified is too small, " "Specify at least %dk", Linux::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())); Linux::capture_initial_stack(JavaThread::stack_size_at_create()); Linux::libpthread_init(); if (PrintMiscellaneous && (Verbose || WizardMode)) { tty->print_cr("[HotSpot is running with %s, %s(%s)]\n", Linux::glibc_version(), Linux::libpthread_version(), Linux::is_floating_stack() ? "floating stack" : "fixed stack"); } if (UseNUMA) { if (!Linux::libnuma_init()) { UseNUMA = false; } else { if ((Linux::numa_max_node() < 1)) { // There's only one node(they start from 0), disable NUMA. UseNUMA = false; } } if (!UseNUMA && ForceNUMA) { UseNUMA = true; } } 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; status = setrlimit(RLIMIT_NOFILE, &nbr_files); if (status != 0) { if (PrintMiscellaneous && (Verbose || WizardMode)) perror("os::init_2 setrlimit failed"); } } } // Initialize lock used to serialize thread creation (see os::create_thread) Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false)); // Initialize HPI. jint hpi_result = hpi::initialize(); if (hpi_result != JNI_OK) { tty->print_cr("There was an error trying to initialize the HPI library."); return hpi_result; } // 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(); return JNI_OK; } // Mark the polling page as unreadable void os::make_polling_page_unreadable(void) { if( !guard_memory((char*)_polling_page, Linux::page_size()) ) fatal("Could not disable polling page"); }; // Mark the polling page as readable void os::make_polling_page_readable(void) { if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) { fatal("Could not enable polling page"); } }; int os::active_processor_count() { // Linux doesn't yet have a (official) notion of processor sets, // so just return the number of online processors. int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN); assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check"); return online_cpus; } 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; } /// // 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"); ExtendedPC epc; OSThread* osthread = thread->osthread(); if (do_suspend(osthread)) { if (osthread->ucontext() != NULL) { epc = os::Linux::ucontext_get_pc(osthread->ucontext()); } else { // NULL context is unexpected, double-check this is the VMThread guarantee(thread->is_VM_thread(), "can only be called for VMThread"); } do_resume(osthread); } // failure means pthread_kill failed for some reason - arguably this is // a fatal problem, but such problems are ignored elsewhere return epc; } int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime) { if (is_NPTL()) { return pthread_cond_timedwait(_cond, _mutex, _abstime); } else { #ifndef IA64 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control // word back to default 64bit precision if condvar is signaled. Java // wants 53bit precision. Save and restore current value. int fpu = get_fpu_control_word(); #endif // IA64 int status = pthread_cond_timedwait(_cond, _mutex, _abstime); #ifndef IA64 set_fpu_control_word(fpu); #endif // IA64 return status; } } //////////////////////////////////////////////////////////////////////////////// // debug support #ifndef PRODUCT static address same_page(address x, address y) { int page_bits = -os::vm_page_size(); if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits)) return x; else if (x > y) return (address)(intptr_t(y) | ~page_bits) + 1; else return (address)(intptr_t(y) & page_bits); } bool os::find(address addr) { Dl_info dlinfo; memset(&dlinfo, 0, sizeof(dlinfo)); if (dladdr(addr, &dlinfo)) { tty->print(PTR_FORMAT ": ", addr); if (dlinfo.dli_sname != NULL) { tty->print("%s+%#x", dlinfo.dli_sname, addr - (intptr_t)dlinfo.dli_saddr); } else if (dlinfo.dli_fname) { tty->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase); } else { tty->print("<absolute address>"); } if (dlinfo.dli_fname) { tty->print(" in %s", dlinfo.dli_fname); } if (dlinfo.dli_fbase) { tty->print(" at " PTR_FORMAT, dlinfo.dli_fbase); } tty->cr(); if (Verbose) { // decode some bytes around the PC address begin = same_page(addr-40, addr); address end = same_page(addr+40, addr); 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) && dlinfo2.dli_saddr != dlinfo.dli_saddr && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) end = (address) dlinfo2.dli_saddr; Disassembler::decode(begin, end); } return true; } return false; } #endif //////////////////////////////////////////////////////////////////////////////// // misc // This does not do anything on Linux. 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; } hpi::native_path(strcpy(pathbuf, path)); return ::stat(pathbuf, sbuf); } bool os::check_heap(bool force) { return true; } 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; } // 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 ::open64(path, oflags, S_IREAD | S_IWRITE); } // return current position of file pointer jlong os::current_file_offset(int fd) { return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR); } // move file pointer to the specified offset jlong os::seek_to_file_offset(int fd, jlong offset) { return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET); } // Map a block of memory. char* os::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::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::unmap_memory(char* addr, size_t bytes) { return munmap(addr, bytes) == 0; } static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time); static clockid_t thread_cpu_clockid(Thread* thread) { pthread_t tid = thread->osthread()->pthread_id(); clockid_t clockid; // Get thread clockid int rc = os::Linux::pthread_getcpuclockid(tid, &clockid); assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code"); return clockid; } // 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() { if (os::Linux::supports_fast_thread_cpu_time()) { return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); } else { // return user + sys since the cost is the same return slow_thread_cpu_time(Thread::current(), true /* user + sys */); } } jlong os::thread_cpu_time(Thread* thread) { // consistent with what current_thread_cpu_time() returns if (os::Linux::supports_fast_thread_cpu_time()) { return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); } else { return slow_thread_cpu_time(thread, true /* user + sys */); } } jlong os::current_thread_cpu_time(bool user_sys_cpu_time) { if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID); } else { return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time); } } jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) { return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread)); } else { return slow_thread_cpu_time(thread, user_sys_cpu_time); } } // // -1 on error. // static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) { static bool proc_pid_cpu_avail = true; static bool proc_task_unchecked = true; static const char *proc_stat_path = "/proc/%d/stat"; pid_t tid = thread->osthread()->thread_id(); int i; char *s; char stat[2048]; int statlen; char proc_name[64]; int count; long sys_time, user_time; char string[64]; int idummy; long ldummy; FILE *fp; // We first try accessing /proc/<pid>/cpu since this is faster to // process. If this file is not present (linux kernels 2.5 and above) // then we open /proc/<pid>/stat. if ( proc_pid_cpu_avail ) { sprintf(proc_name, "/proc/%d/cpu", tid); fp = fopen(proc_name, "r"); if ( fp != NULL ) { count = fscanf( fp, "%s %lu %lu\n", string, &user_time, &sys_time); fclose(fp); if ( count != 3 ) return -1; if (user_sys_cpu_time) { return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); } else { return (jlong)user_time * (1000000000 / clock_tics_per_sec); } } else proc_pid_cpu_avail = false; } // The /proc/<tid>/stat aggregates per-process usage on // new Linux kernels 2.6+ where NPTL is supported. // The /proc/self/task/<tid>/stat still has the per-thread usage. // See bug 6328462. // There can be no directory /proc/self/task on kernels 2.4 with NPTL // and possibly in some other cases, so we check its availability. if (proc_task_unchecked && os::Linux::is_NPTL()) { // This is executed only once proc_task_unchecked = false; fp = fopen("/proc/self/task", "r"); if (fp != NULL) { proc_stat_path = "/proc/self/task/%d/stat"; fclose(fp); } } sprintf(proc_name, proc_stat_path, tid); fp = fopen(proc_name, "r"); if ( fp == NULL ) return -1; statlen = fread(stat, 1, 2047, fp); stat[statlen] = '\0'; fclose(fp); // Skip pid and the command string. Note that we could be dealing with // weird command names, e.g. user could decide to rename java launcher // to "java 1.4.2 :)", then the stat file would look like // 1234 (java 1.4.2 :)) R ... ... // We don't really need to know the command string, just find the last // occurrence of ")" and then start parsing from there. See bug 4726580. s = strrchr(stat, ')'); i = 0; if (s == NULL ) return -1; // Skip blank chars do s++; while (isspace(*s)); count = sscanf(s,"%*c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu", &idummy, &idummy, &idummy, &idummy, &idummy, &ldummy, &ldummy, &ldummy, &ldummy, &ldummy, &user_time, &sys_time); if ( count != 12 ) return -1; if (user_sys_cpu_time) { return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec); } else { return (jlong)user_time * (1000000000 / clock_tics_per_sec); } } 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() { return true; } // System loadavg support. Returns -1 if load average cannot be obtained. // Linux 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); } } extern "C" { /** * NOTE: the following code is to keep the green threads code * in the libjava.so happy. Once the green threads is removed, * these code will no longer be needed. */ int jdk_waitpid(pid_t pid, int* status, int options) { return waitpid(pid, status, options); } int fork1() { return fork(); } int jdk_sem_init(sem_t *sem, int pshared, unsigned int value) { return sem_init(sem, pshared, value); } int jdk_sem_post(sem_t *sem) { return sem_post(sem); } int jdk_sem_wait(sem_t *sem) { return sem_wait(sem); } int jdk_pthread_sigmask(int how , const sigset_t* newmask, sigset_t* oldmask) { return pthread_sigmask(how , newmask, oldmask); } } // 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(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 == ETIME) { status = EINTR; } assert_status(status == 0 || status == EINTR, status, "cond_wait"); } -- _nParked ; // In theory we could move the ST of 0 into _Event past the unlock(), // but then we'd need a MEMBAR after the ST. _Event = 0 ; status = pthread_mutex_unlock(_mutex); assert_status(status == 0, status, "mutex_unlock"); } 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::Linux::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 == ETIME || status == ETIMEDOUT, status, "cond_timedwait"); if (!FilterSpuriousWakeups) break ; // previous semantics if (status == ETIME || 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") ; return ret; } void os::PlatformEvent::unpark() { int v, AnyWaiters ; for (;;) { v = _Event ; if (v > 0) { // The LD of _Event could have reordered or be satisfied // by a read-aside from this processor's write buffer. // To avoid problems execute a barrier and then // ratify the value. OrderAccess::fence() ; if (_Event == v) return ; continue ; } if (Atomic::cmpxchg (v+1, &_Event, v) == v) break ; } if (v < 0) { // Wait for the thread associated with the event to vacate int status = pthread_mutex_lock(_mutex); assert_status(status == 0, status, "mutex_lock"); 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 linux 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 NANOSECS_PER_SEC 1000000000 #define NANOSECS_PER_MILLISEC 1000000 #define MAX_SECS 100000000 /* * This code is common to linux 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 Linux) 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(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) { // Optional fast-path check: // Return immediately if a permit is available. if (_counter > 0) { _counter = 0 ; OrderAccess::fence(); 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 timespec absTime; if (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") ; 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::Linux::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::Linux::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 == ETIME || 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") ; // If externally suspended while waiting, re-suspend if (jt->handle_special_suspend_equivalent_condition()) { jt->java_suspend_self(); } OrderAccess::fence(); } 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") ; } } extern char** environ; #ifndef __NR_fork #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) #endif #ifndef __NR_execve #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) #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 LinuxThreads/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 = NOT_IA64(syscall(__NR_fork);) IA64_ONLY(fork();) if (pid < 0) { // fork failed return -1; } else if (pid == 0) { // child process // execve() in LinuxThreads 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. NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);) IA64_ONLY(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; } } }