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code / edge / openjdk / refs/heads/master / . / hotspot / src / os / linux / vm / os_linux.cpp
blob: 292d47886bcd69cd1b41a32d38bba429c4e79342 [file] [log] [blame]
/*
* Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
// no precompiled headers
#include "classfile/classLoader.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "code/icBuffer.hpp"
#include "code/vtableStubs.hpp"
#include "compiler/compileBroker.hpp"
#include "compiler/disassembler.hpp"
#include "interpreter/interpreter.hpp"
#include "jvm_linux.h"
#include "memory/allocation.inline.hpp"
#include "memory/filemap.hpp"
#include "mutex_linux.inline.hpp"
#include "oops/oop.inline.hpp"
#include "os_share_linux.hpp"
#include "prims/jniFastGetField.hpp"
#include "prims/jvm.h"
#include "prims/jvm_misc.hpp"
#include "runtime/arguments.hpp"
#include "runtime/extendedPC.hpp"
#include "runtime/globals.hpp"
#include "runtime/interfaceSupport.hpp"
#include "runtime/init.hpp"
#include "runtime/java.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/objectMonitor.hpp"
#include "runtime/orderAccess.inline.hpp"
#include "runtime/osThread.hpp"
#include "runtime/perfMemory.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/statSampler.hpp"
#include "runtime/stubRoutines.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/threadCritical.hpp"
#include "runtime/timer.hpp"
#include "services/attachListener.hpp"
#include "services/memTracker.hpp"
#include "services/runtimeService.hpp"
#include "utilities/decoder.hpp"
#include "utilities/defaultStream.hpp"
#include "utilities/events.hpp"
#include "utilities/elfFile.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/vmError.hpp"
// put OS-includes here
# include <sys/types.h>
# include <sys/mman.h>
# include <sys/stat.h>
# include <sys/select.h>
# include <pthread.h>
# include <signal.h>
# include <errno.h>
# include <dlfcn.h>
# include <stdio.h>
# include <unistd.h>
# include <sys/resource.h>
# include <pthread.h>
# include <sys/stat.h>
# include <sys/time.h>
# include <sys/times.h>
# include <sys/utsname.h>
# include <sys/socket.h>
# include <sys/wait.h>
# include <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>
# include <sys/ioctl.h>
PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#include <sched.h>
#undef _GNU_SOURCE
#else
#include <sched.h>
#endif
// if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
// getrusage() is prepared to handle the associated failure.
#ifndef RUSAGE_THREAD
#define RUSAGE_THREAD (1) /* only the calling thread */
#endif
#define MAX_PATH (2 * K)
#define MAX_SECS 100000000
// for timer info max values which include all bits
#define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
#define LARGEPAGES_BIT (1 << 6)
////////////////////////////////////////////////////////////////////////////////
// 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;
const int os::Linux::_vm_default_page_size = (8 * K);
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;
pthread_condattr_t os::Linux::_condattr[1];
static jlong initial_time_count=0;
static int clock_tics_per_sec = 100;
// For diagnostics to print a message once. see run_periodic_checks
static sigset_t check_signal_done;
static bool check_signals = true;
static pid_t _initial_pid = 0;
/* Signal number used to suspend/resume a thread */
/* do not use any signal number less than SIGSEGV, see 4355769 */
static int SR_signum = SIGUSR2;
sigset_t SR_sigset;
/* Used to protect dlsym() calls */
static pthread_mutex_t dl_mutex;
// Declarations
static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
// utility functions
static int SR_initialize();
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();
}
////////////////////////////////////////////////////////////////////////////////
// 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
#else
#ifdef __i386__
#define SYS_gettid 224
#else
#ifdef __amd64__
#define SYS_gettid 186
#else
#ifdef __sparc__
#define SYS_gettid 143
#else
#error define gettid for the arch
#endif
#endif
#endif
#endif
#endif
// Cpu architecture string
static char cpu_arch[] = HOTSPOT_LIB_ARCH;
// 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() {
// The next steps are taken in the product version:
//
// Obtain the JAVA_HOME value from the location of libjvm.so.
// This library should be located at:
// <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
//
// If "/jre/lib/" appears at the right place in the path, then we
// assume libjvm.so is installed in a JDK and we use this path.
//
// Otherwise exit with message: "Could not create the Java virtual machine."
//
// The following extra steps are taken in the debugging version:
//
// If "/jre/lib/" does NOT appear at the right place in the path
// instead of exit check for $JAVA_HOME environment variable.
//
// If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
// then we append a fake suffix "hotspot/libjvm.so" to this path so
// it looks like libjvm.so is installed there
// <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
//
// Otherwise exit.
//
// Important note: if the location of libjvm.so changes this
// code needs to be changed accordingly.
// See ld(1):
// The linker uses the following search paths to locate required
// shared libraries:
// 1: ...
// ...
// 7: The default directories, normally /lib and /usr/lib.
#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
// Base path of extensions installed on the system.
#define SYS_EXT_DIR "/usr/java/packages"
#define EXTENSIONS_DIR "/lib/ext"
#define ENDORSED_DIR "/lib/endorsed"
// Buffer that fits several sprintfs.
// Note that the space for the colon and the trailing null are provided
// by the nulls included by the sizeof operator.
const size_t bufsize =
MAX3((size_t)MAXPATHLEN, // For dll_dir & friends.
(size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir
(size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir
char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
// sysclasspath, java_home, dll_dir
{
char *pslash;
os::jvm_path(buf, bufsize);
// Found the full path to libjvm.so.
// Now cut the path to <java_home>/jre if we can.
*(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so.
pslash = strrchr(buf, '/');
if (pslash != NULL) {
*pslash = '\0'; // Get rid of /{client|server|hotspot}.
}
Arguments::set_dll_dir(buf);
if (pslash != NULL) {
pslash = strrchr(buf, '/');
if (pslash != NULL) {
*pslash = '\0'; // Get rid of /<arch>.
pslash = strrchr(buf, '/');
if (pslash != NULL) {
*pslash = '\0'; // Get rid of /lib.
}
}
}
Arguments::set_java_home(buf);
set_boot_path('/', ':');
}
// Where to look for native libraries.
//
// Note: Due to a legacy implementation, most of the library path
// is set in the launcher. This was to accomodate linking restrictions
// on legacy 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.
{
// Get the user setting of LD_LIBRARY_PATH, and prepended it. It
// should always exist (until the legacy problem cited above is
// addressed).
const char *v = ::getenv("LD_LIBRARY_PATH");
const char *v_colon = ":";
if (v == NULL) { v = ""; v_colon = ""; }
// That's +1 for the colon and +1 for the trailing '\0'.
char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
strlen(v) + 1 +
sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
mtInternal);
sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
Arguments::set_library_path(ld_library_path);
FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal);
}
// Extensions directories.
sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
Arguments::set_ext_dirs(buf);
// Endorsed standards default directory.
sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
Arguments::set_endorsed_dirs(buf);
FREE_C_HEAP_ARRAY(char, buf, mtInternal);
#undef DEFAULT_LIBPATH
#undef SYS_EXT_DIR
#undef EXTENSIONS_DIR
#undef ENDORSED_DIR
}
////////////////////////////////////////////////////////////////////////////////
// breakpoint support
void os::breakpoint() {
BREAKPOINT;
}
extern "C" void breakpoint() {
// use debugger to set breakpoint here
}
////////////////////////////////////////////////////////////////////////////////
// signal support
debug_only(static bool signal_sets_initialized = false);
static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
bool os::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);
#if defined(PPC64)
sigaddset(&unblocked_sigs, SIGTRAP);
#endif
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, mtInternal);
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, mtInternal);
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
assert (JavaThread::stack_size_at_create() > 0, "this should be set");
stack_size = JavaThread::stack_size_at_create();
break;
case os::compiler_thread:
if (CompilerThreadStackSize > 0) {
stack_size = (size_t)(CompilerThreadStackSize * K);
break;
} // else fall through:
// use VMThreadStackSize if CompilerThreadStackSize is not defined
case os::vm_thread:
case os::pgc_thread:
case os::cgc_thread:
case os::watcher_thread:
if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
break;
}
}
stack_size = MAX2(stack_size, os::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
// Restore the thread pointer if the destructor is called. This is in case
// someone from JNI code sets up a destructor with pthread_key_create to run
// detachCurrentThread on thread death. Unless we restore the thread pointer we
// will hang or crash. When detachCurrentThread is called the key will be set
// to null and we will not be called again. If detachCurrentThread is never
// called we could loop forever depending on the pthread implementation.
static void restore_thread_pointer(void* p) {
Thread* thread = (Thread*) p;
os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
}
int os::allocate_thread_local_storage() {
pthread_key_t key;
int rslt = pthread_key_create(&key, restore_thread_pointer);
assert(rslt == 0, "cannot allocate thread local storage");
return (int)key;
}
// Note: This is currently not used by VM, as we don't destroy TLS key
// on VM exit.
void os::free_thread_local_storage(int index) {
int rslt = pthread_key_delete((pthread_key_t)index);
assert(rslt == 0, "invalid index");
}
void os::thread_local_storage_at_put(int index, void* value) {
int rslt = pthread_setspecific((pthread_key_t)index, value);
assert(rslt == 0, "pthread_setspecific failed");
}
extern "C" Thread* get_thread() {
return ThreadLocalStorage::thread();
}
//////////////////////////////////////////////////////////////////////////////
// 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?
// Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
if (stack_size > 2 * K * K IA64_ONLY(*2))
stack_size = 2 * K * K IA64_ONLY(*2);
// 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;
intptr_t rss;
uintptr_t 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));
#define _UFM UINTX_FORMAT
#define _DFM INTX_FORMAT
/* 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 " _UFM _UFM _DFM _UFM _UFM _UFM _UFM,
&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 INTX_FORMAT */
&rsslim, /* 25 UINTX_FORMAT */
&scodes, /* 26 UINTX_FORMAT */
&ecode, /* 27 UINTX_FORMAT */
&stack_start); /* 28 UINTX_FORMAT */
}
#undef _UFM
#undef _DFM
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()) / os::elapsed_frequency(); // nanosecond resolution
}
jlong os::elapsed_counter() {
return javaTimeNanos() - initial_time_count;
}
jlong os::elapsed_frequency() {
return NANOSECS_PER_SEC; // nanosecond resolution
}
bool os::supports_vtime() { return true; }
bool os::enable_vtime() { return false; }
bool os::vtime_enabled() { return false; }
double os::elapsedVTime() {
struct rusage usage;
int retval = getrusage(RUSAGE_THREAD, &usage);
if (retval == 0) {
return (double) (usage.ru_utime.tv_sec + usage.ru_stime.tv_sec) + (double) (usage.ru_utime.tv_usec + usage.ru_stime.tv_usec) / (1000 * 1000);
} else {
// 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;
return;
} else {
// close librt if there is no monotonic clock
dlclose(handle);
}
}
}
warning("No monotonic clock was available - timed services may " \
"be adversely affected if the time-of-day clock changes");
}
#ifndef SYS_clock_getres
#if defined(IA32) || defined(AMD64)
#define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
#else
#warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
#define sys_clock_getres(x,y) -1
#endif
#else
#define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
#endif
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();
}
// This method is a copy of JDK's sysGetLastErrorString
// from src/solaris/hpi/src/system_md.c
size_t os::lasterror(char *buf, size_t len) {
if (errno == 0) return 0;
const char *s = ::strerror(errno);
size_t n = ::strlen(s);
if (n >= len) {
n = len - 1;
}
::strncpy(buf, s, n);
buf[n] = '\0';
return n;
}
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"; }
// This must be hard coded because it's the system's temporary
// directory not the java application's temp directory, ala java.io.tmpdir.
const char* os::get_temp_directory() { return "/tmp"; }
static bool file_exists(const char* filename) {
struct stat statbuf;
if (filename == NULL || strlen(filename) == 0) {
return false;
}
return os::stat(filename, &statbuf) == 0;
}
bool os::dll_build_name(char* buffer, size_t buflen,
const char* pname, const char* fname) {
bool retval = false;
// Copied from libhpi
const size_t pnamelen = pname ? strlen(pname) : 0;
// Return error on buffer overflow.
if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
return retval;
}
if (pnamelen == 0) {
snprintf(buffer, buflen, "lib%s.so", fname);
retval = true;
} else if (strchr(pname, *os::path_separator()) != NULL) {
int n;
char** pelements = split_path(pname, &n);
if (pelements == NULL) {
return false;
}
for (int i = 0 ; i < n ; i++) {
// Really shouldn't be NULL, but check can't hurt
if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
continue; // skip the empty path values
}
snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
if (file_exists(buffer)) {
retval = true;
break;
}
}
// release the storage
for (int i = 0 ; i < n ; i++) {
if (pelements[i] != NULL) {
FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
}
}
if (pelements != NULL) {
FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
}
} else {
snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
retval = true;
}
return retval;
}
// check if addr is inside libjvm.so
bool os::address_is_in_vm(address addr) {
static address libjvm_base_addr;
Dl_info dlinfo;
if (libjvm_base_addr == NULL) {
if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
libjvm_base_addr = (address)dlinfo.dli_fbase;
}
assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
}
if (dladdr((void *)addr, &dlinfo) != 0) {
if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
}
return false;
}
bool os::dll_address_to_function_name(address addr, char *buf,
int buflen, int *offset) {
// buf is not optional, but offset is optional
assert(buf != NULL, "sanity check");
Dl_info dlinfo;
if (dladdr((void*)addr, &dlinfo) != 0) {
// see if we have a matching symbol
if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
}
if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
return true;
}
// no matching symbol so try for just file info
if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
buf, buflen, offset, dlinfo.dli_fname)) {
return true;
}
}
}
buf[0] = '\0';
if (offset != NULL) *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) {
// buf is not optional, but offset is optional
assert(buf != NULL, "sanity check");
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;
}
if (dladdr((void*)addr, &dlinfo) != 0) {
if (dlinfo.dli_fname != NULL) {
jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
}
if (dlinfo.dli_fbase != NULL && offset != NULL) {
*offset = addr - (address)dlinfo.dli_fbase;
}
return true;
}
buf[0] = '\0';
if (offset) *offset = -1;
return false;
}
// Loads .dll/.so and
// in case of error it checks if .dll/.so was built for the
// same architecture as Hotspot is running on
// Remember the stack's state. The Linux dynamic linker will change
// the stack to 'executable' at most once, so we must safepoint only once.
bool os::Linux::_stack_is_executable = false;
// VM operation that loads a library. This is necessary if stack protection
// of the Java stacks can be lost during loading the library. If we
// do not stop the Java threads, they can stack overflow before the stacks
// are protected again.
class VM_LinuxDllLoad: public VM_Operation {
private:
const char *_filename;
char *_ebuf;
int _ebuflen;
void *_lib;
public:
VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
_filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
VMOp_Type type() const { return VMOp_LinuxDllLoad; }
void doit() {
_lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
os::Linux::_stack_is_executable = true;
}
void* loaded_library() { return _lib; }
};
void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
{
void * result = NULL;
bool load_attempted = false;
// Check whether the library to load might change execution rights
// of the stack. If they are changed, the protection of the stack
// guard pages will be lost. We need a safepoint to fix this.
//
// See Linux man page execstack(8) for more info.
if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
ElfFile ef(filename);
if (!ef.specifies_noexecstack()) {
if (!is_init_completed()) {
os::Linux::_stack_is_executable = true;
// This is OK - No Java threads have been created yet, and hence no
// stack guard pages to fix.
//
// This should happen only when you are building JDK7 using a very
// old version of JDK6 (e.g., with JPRT) and running test_gamma.
//
// Dynamic loader will make all stacks executable after
// this function returns, and will not do that again.
assert(Threads::first() == NULL, "no Java threads should exist yet.");
} else {
warning("You have loaded library %s which might have disabled stack guard. "
"The VM will try to fix the stack guard now.\n"
"It's highly recommended that you fix the library with "
"'execstack -c <libfile>', or link it with '-z noexecstack'.",
filename);
assert(Thread::current()->is_Java_thread(), "must be Java thread");
JavaThread *jt = JavaThread::current();
if (jt->thread_state() != _thread_in_native) {
// This happens when a compiler thread tries to load a hsdis-<arch>.so file
// that requires ExecStack. Cannot enter safe point. Let's give up.
warning("Unable to fix stack guard. Giving up.");
} else {
if (!LoadExecStackDllInVMThread) {
// This is for the case where the DLL has an static
// constructor function that executes JNI code. We cannot
// load such DLLs in the VMThread.
result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
}
ThreadInVMfromNative tiv(jt);
debug_only(VMNativeEntryWrapper vew;)
VM_LinuxDllLoad op(filename, ebuf, ebuflen);
VMThread::execute(&op);
if (LoadExecStackDllInVMThread) {
result = op.loaded_library();
}
load_attempted = true;
}
}
}
}
if (!load_attempted) {
result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
}
if (result != NULL) {
// Successful loading
return result;
}
Elf32_Ehdr elf_head;
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"},
#if defined(VM_LITTLE_ENDIAN)
{EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
#else
{EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
#endif
{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;
}
void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) {
void * result = ::dlopen(filename, RTLD_LAZY);
if (result == NULL) {
::strncpy(ebuf, ::dlerror(), ebuflen - 1);
ebuf[ebuflen-1] = '\0';
}
return result;
}
void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) {
void * result = NULL;
if (LoadExecStackDllInVMThread) {
result = dlopen_helper(filename, ebuf, ebuflen);
}
// Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
// library that requires an executable stack, or which does not have this
// stack attribute set, dlopen changes the stack attribute to executable. The
// read protection of the guard pages gets lost.
//
// Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
// may have been queued at the same time.
if (!_stack_is_executable) {
JavaThread *jt = Threads::first();
while (jt) {
if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
warning("Attempt to reguard stack yellow zone failed.");
}
}
jt = jt->next();
}
}
return result;
}
/*
* 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;
}
void* os::get_default_process_handle() {
return (void*)::dlopen(NULL, RTLD_LAZY);
}
static bool _print_ascii_file(const char* filename, outputStream* st) {
int fd = ::open(filename, O_RDONLY);
if (fd == -1) {
return false;
}
char buf[32];
int bytes;
while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
st->print_raw(buf, bytes);
}
::close(fd);
return true;
}
void os::print_dll_info(outputStream *st) {
st->print_cr("Dynamic libraries:");
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_brief(outputStream* st) {
os::Linux::print_distro_info(st);
os::Posix::print_uname_info(st);
os::Linux::print_libversion_info(st);
}
void os::print_os_info(outputStream* st) {
st->print("OS:");
os::Linux::print_distro_info(st);
os::Posix::print_uname_info(st);
// Print warning if unsafe chroot environment detected
if (unsafe_chroot_detected) {
st->print("WARNING!! ");
st->print_cr("%s", unstable_chroot_error);
}
os::Linux::print_libversion_info(st);
os::Posix::print_rlimit_info(st);
os::Posix::print_load_average(st);
os::Linux::print_full_memory_info(st);
}
// Try to identify popular distros.
// Most Linux distributions have a /etc/XXX-release file, which contains
// the OS version string. Newer Linux distributions have a /etc/lsb-release
// file that also 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.
// Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
// their own specific XXX-release file as well as a redhat-release file.
// Because of this the XXX-release file needs to be searched for before the
// redhat-release file.
// Since Red Hat has a lsb-release file that is not very descriptive the
// search for redhat-release needs to be before lsb-release.
// Since the lsb-release file is the new standard it needs to be searched
// before the older style release files.
// Searching system-release (Red Hat) and os-release (other Linuxes) are a
// next to last resort. The os-release file is a new standard that contains
// distribution information and the system-release file seems to be an old
// standard that has been replaced by the lsb-release and os-release files.
// Searching for the debian_version file is the last resort. It contains
// an informative string like "6.0.6" or "wheezy/sid". Because of this
// "Debian " is printed before the contents of the debian_version file.
void os::Linux::print_distro_info(outputStream* st) {
if (!_print_ascii_file("/etc/oracle-release", st) &&
!_print_ascii_file("/etc/mandriva-release", st) &&
!_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/lsb-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/ltib-release", st) &&
!_print_ascii_file("/etc/angstrom-version", st) &&
!_print_ascii_file("/etc/system-release", st) &&
!_print_ascii_file("/etc/os-release", st)) {
if (file_exists("/etc/debian_version")) {
st->print("Debian ");
_print_ascii_file("/etc/debian_version", st);
} else {
st->print("Linux");
}
}
st->cr();
}
void os::Linux::print_libversion_info(outputStream* st) {
// libc, pthread
st->print("libc:");
st->print("%s ", os::Linux::glibc_version());
st->print("%s ", os::Linux::libpthread_version());
if (os::Linux::is_LinuxThreads()) {
st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
}
st->cr();
}
void os::Linux::print_full_memory_info(outputStream* st) {
st->print("\n/proc/meminfo:\n");
_print_ascii_file("/proc/meminfo", st);
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();
}
void os::pd_print_cpu_info(outputStream* st) {
st->print("\n/proc/cpuinfo:\n");
if (!_print_ascii_file("/proc/cpuinfo", st)) {
st->print(" <Not Available>");
}
st->cr();
}
void os::print_siginfo(outputStream* st, void* siginfo) {
const siginfo_t* si = (const siginfo_t*)siginfo;
os::Posix::print_siginfo_brief(st, si);
#if INCLUDE_CDS
if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
UseSharedSpaces) {
FileMapInfo* mapinfo = FileMapInfo::current_info();
if (mapinfo->is_in_shared_space(si->si_addr)) {
st->print("\n\nError accessing class data sharing archive." \
" Mapped file inaccessible during execution, " \
" possible disk/network problem.");
}
}
#endif
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);
#if defined(PPC64)
print_signal_handler(st, SIGTRAP, buf, buflen);
#endif
}
static char saved_jvm_path[MAXPATHLEN] = {0};
// Find the full path to the current module, libjvm.so
void os::jvm_path(char *buf, jint buflen) {
// Error checking.
if (buflen < MAXPATHLEN) {
assert(false, "must use a large-enough buffer");
buf[0] = '\0';
return;
}
// Lazy resolve the path to current module.
if (saved_jvm_path[0] != 0) {
strcpy(buf, saved_jvm_path);
return;
}
char dli_fname[MAXPATHLEN];
bool ret = dll_address_to_library_name(
CAST_FROM_FN_PTR(address, os::jvm_path),
dli_fname, sizeof(dli_fname), NULL);
assert(ret, "cannot locate libjvm");
char *rp = NULL;
if (ret && dli_fname[0] != '\0') {
rp = realpath(dli_fname, buf);
}
if (rp == NULL)
return;
if (Arguments::created_by_gamma_launcher()) {
// Support for the gamma launcher. Typical value for buf is
// "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.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) {
char* jrelib_p;
int len;
// Check the current module name "libjvm.so".
p = strrchr(buf, '/');
assert(strstr(p, "/libjvm") == p, "invalid library name");
rp = realpath(java_home_var, buf);
if (rp == NULL)
return;
// determine if this is a legacy image or modules image
// modules image doesn't have "jre" subdirectory
len = strlen(buf);
assert(len < buflen, "Ran out of buffer room");
jrelib_p = buf + len;
snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
if (0 != access(buf, F_OK)) {
snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
}
if (0 == access(buf, F_OK)) {
// Use current module name "libjvm.so"
len = strlen(buf);
snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
} else {
// Go back to path of .so
rp = realpath(dli_fname, buf);
if (rp == NULL)
return;
}
}
}
}
strncpy(saved_jvm_path, buf, MAXPATHLEN);
}
void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
// no prefix required, not even "_"
}
void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
// no suffix required
}
////////////////////////////////////////////////////////////////////////////////
// sun.misc.Signal support
static volatile jint sigint_count = 0;
static void
UserHandler(int sig, void *siginfo, void *context) {
// 4511530 - sem_post is serialized and handled by the manager thread. When
// the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
// don't want to flood the manager thread with sem_post requests.
if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
return;
// Ctrl-C is pressed during error reporting, likely because the error
// handler fails to abort. Let VM die immediately.
if (sig == SIGINT && is_error_reported()) {
os::die();
}
os::signal_notify(sig);
}
void* os::user_handler() {
return CAST_FROM_FN_PTR(void*, UserHandler);
}
class Semaphore : public StackObj {
public:
Semaphore();
~Semaphore();
void signal();
void wait();
bool trywait();
bool timedwait(unsigned int sec, int nsec);
private:
sem_t _semaphore;
};
Semaphore::Semaphore() {
sem_init(&_semaphore, 0, 0);
}
Semaphore::~Semaphore() {
sem_destroy(&_semaphore);
}
void Semaphore::signal() {
sem_post(&_semaphore);
}
void Semaphore::wait() {
sem_wait(&_semaphore);
}
bool Semaphore::trywait() {
return sem_trywait(&_semaphore) == 0;
}
bool Semaphore::timedwait(unsigned int sec, int nsec) {
struct timespec ts;
// Semaphore's are always associated with CLOCK_REALTIME
os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
// see unpackTime for discussion on overflow checking
if (sec >= MAX_SECS) {
ts.tv_sec += MAX_SECS;
ts.tv_nsec = 0;
} else {
ts.tv_sec += sec;
ts.tv_nsec += nsec;
if (ts.tv_nsec >= NANOSECS_PER_SEC) {
ts.tv_nsec -= NANOSECS_PER_SEC;
++ts.tv_sec; // note: this must be <= max_secs
}
}
while (1) {
int result = sem_timedwait(&_semaphore, &ts);
if (result == 0) {
return true;
} else if (errno == EINTR) {
continue;
} else if (errno == ETIMEDOUT) {
return false;
} else {
return false;
}
}
}
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;
static Semaphore sr_semaphore;
void os::signal_init_pd() {
// Initialize signal structures
::memset((void*)pending_signals, 0, sizeof(pending_signals));
// Initialize signal semaphore
::sem_init(&sig_sem, 0, 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[PATH_MAX+1];
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);
}
}
static bool recoverable_mmap_error(int err) {
// See if the error is one we can let the caller handle. This
// list of errno values comes from JBS-6843484. I can't find a
// Linux man page that documents this specific set of errno
// values so while this list currently matches Solaris, it may
// change as we gain experience with this failure mode.
switch (err) {
case EBADF:
case EINVAL:
case ENOTSUP:
// let the caller deal with these errors
return true;
default:
// Any remaining errors on this OS can cause our reserved mapping
// to be lost. That can cause confusion where different data
// structures think they have the same memory mapped. The worst
// scenario is if both the VM and a library think they have the
// same memory mapped.
return false;
}
}
static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
int err) {
warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
", %d) failed; error='%s' (errno=%d)", addr, size, exec,
strerror(err), err);
}
static void warn_fail_commit_memory(char* addr, size_t size,
size_t alignment_hint, bool exec,
int err) {
warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
alignment_hint, exec, strerror(err), err);
}
// 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.
int os::Linux::commit_memory_impl(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);
if (res != (uintptr_t) MAP_FAILED) {
if (UseNUMAInterleaving) {
numa_make_global(addr, size);
}
return 0;
}
int err = errno; // save errno from mmap() call above
if (!recoverable_mmap_error(err)) {
warn_fail_commit_memory(addr, size, exec, err);
vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
}
return err;
}
bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
return os::Linux::commit_memory_impl(addr, size, exec) == 0;
}
void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
const char* mesg) {
assert(mesg != NULL, "mesg must be specified");
int err = os::Linux::commit_memory_impl(addr, size, exec);
if (err != 0) {
// the caller wants all commit errors to exit with the specified mesg:
warn_fail_commit_memory(addr, size, exec, err);
vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
}
}
// Define MAP_HUGETLB here so we can build HotSpot on old systems.
#ifndef MAP_HUGETLB
#define MAP_HUGETLB 0x40000
#endif
// Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
#ifndef MADV_HUGEPAGE
#define MADV_HUGEPAGE 14
#endif
int os::Linux::commit_memory_impl(char* addr, size_t size,
size_t alignment_hint, bool exec) {
int err = os::Linux::commit_memory_impl(addr, size, exec);
if (err == 0) {
realign_memory(addr, size, alignment_hint);
}
return err;
}
bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
bool exec) {
return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
}
void os::pd_commit_memory_or_exit(char* addr, size_t size,
size_t alignment_hint, bool exec,
const char* mesg) {
assert(mesg != NULL, "mesg must be specified");
int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
if (err != 0) {
// the caller wants all commit errors to exit with the specified mesg:
warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
}
}
void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
// We don't check the return value: madvise(MADV_HUGEPAGE) may not
// be supported or the memory may already be backed by huge pages.
::madvise(addr, bytes, MADV_HUGEPAGE);
}
}
void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
// This method works by doing an mmap over an existing mmaping and effectively discarding
// the existing pages. However it won't work for SHM-based large pages that cannot be
// uncommitted at all. We don't do anything in this case to avoid creating a segment with
// small pages on top of the SHM segment. This method always works for small pages, so we
// allow that in any case.
if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
commit_memory(addr, bytes, alignment_hint, !ExecMem);
}
}
void os::numa_make_global(char *addr, size_t bytes) {
Linux::numa_interleave_memory(addr, bytes);
}
// Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
// bind policy to MPOL_PREFERRED for the current thread.
#define USE_MPOL_PREFERRED 0
void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
// To make NUMA and large pages more robust when both enabled, we need to ease
// the requirements on where the memory should be allocated. MPOL_BIND is the
// default policy and it will force memory to be allocated on the specified
// node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
// the specified node, but will not force it. Using this policy will prevent
// getting SIGBUS when trying to allocate large pages on NUMA nodes with no
// free large pages.
Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
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;
}
int os::Linux::sched_getcpu_syscall(void) {
unsigned int cpu = 0;
int retval = -1;
#if defined(IA32)
# ifndef SYS_getcpu
# define SYS_getcpu 318
# endif
retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
#elif defined(AMD64)
// Unfortunately we have to bring all these macros here from vsyscall.h
// to be able to compile on old linuxes.
# define __NR_vgetcpu 2
# define VSYSCALL_START (-10UL << 20)
# define VSYSCALL_SIZE 1024
# define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
retval = vgetcpu(&cpu, NULL, NULL);
#endif
return (retval == -1) ? retval : cpu;
}
// Something to do with the numa-aware allocator needs these symbols
extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
extern "C" JNIEXPORT void numa_error(char *where) { }
extern "C" JNIEXPORT int fork1() { return fork(); }
// 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 it's not, try a direct syscall.
if (sched_getcpu() == -1)
set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
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")));
set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
libnuma_dlsym(handle, "numa_set_bind_policy")));
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, mtInternal) 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 = 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, mtInternal);
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, mtInternal);
}
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;
os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
unsigned long* os::Linux::_numa_all_nodes;
bool os::pd_uncommit_memory(char* addr, size_t size) {
uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
return res != (uintptr_t) MAP_FAILED;
}
static
address get_stack_commited_bottom(address bottom, size_t size) {
address nbot = bottom;
address ntop = bottom + size;
size_t page_sz = os::vm_page_size();
unsigned pages = size / page_sz;
unsigned char vec[1];
unsigned imin = 1, imax = pages + 1, imid;
int mincore_return_value = 0;
assert(imin <= imax, "Unexpected page size");
while (imin < imax) {
imid = (imax + imin) / 2;
nbot = ntop - (imid * page_sz);
// Use a trick with mincore to check whether the page is mapped or not.
// mincore sets vec to 1 if page resides in memory and to 0 if page
// is swapped output but if page we are asking for is unmapped
// it returns -1,ENOMEM
mincore_return_value = mincore(nbot, page_sz, vec);
if (mincore_return_value == -1) {
// Page is not mapped go up
// to find first mapped page
if (errno != EAGAIN) {
assert(errno == ENOMEM, "Unexpected mincore errno");
imax = imid;
}
} else {
// Page is mapped go down
// to find first not mapped page
imin = imid + 1;
}
}
nbot = nbot + page_sz;
// Adjust stack bottom one page up if last checked page is not mapped
if (mincore_return_value == -1) {
nbot = nbot + page_sz;
}
return nbot;
}
// 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.
// 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.
// 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. This only affects the main/initial thread
bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
if (os::Linux::is_initial_thread()) {
// As we manually grow stack up to bottom inside create_attached_thread(),
// it's likely that os::Linux::initial_thread_stack_bottom is mapped and
// we don't need to do anything special.
// Check it first, before calling heavy function.
uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
unsigned char vec[1];
if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
// Fallback to slow path on all errors, including EAGAIN
stack_extent = (uintptr_t) get_stack_commited_bottom(
os::Linux::initial_thread_stack_bottom(),
(size_t)addr - stack_extent);
}
if (stack_extent < (uintptr_t)addr) {
::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
}
}
return os::commit_memory(addr, size, !ExecMem);
}
// If this is a growable mapping, remove the guard pages entirely by
// munmap()ping them. If not, just call uncommit_memory(). This only
// affects the main/initial thread, but guard against future OS changes
// It's safe to always unmap guard pages for initial thread because we
// always place it right after end of the mapped region
bool os::remove_stack_guard_pages(char* addr, size_t size) {
uintptr_t stack_extent, stack_base;
if (os::Linux::is_initial_thread()) {
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 reserved/uncommitted pages PROT_NONE so we fail early if we
// touch an uncommitted page. Otherwise, the read/write might
// succeed if we have enough swap space to back the physical page.
addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
flags, -1, 0);
if (addr != MAP_FAILED) {
// anon_mmap() should only get called during VM initialization,
// don't need lock (actually we can skip locking even it can be called
// from multiple threads, because _highest_vm_reserved_address is just a
// hint about the upper limit of non-stack memory regions.)
if ((address)addr + bytes > _highest_vm_reserved_address) {
_highest_vm_reserved_address = (address)addr + bytes;
}
}
return addr == MAP_FAILED ? NULL : addr;
}
// Allocate (using mmap, NO_RESERVE, with small pages) at either a given request address
// (req_addr != NULL) or with a given alignment.
// - bytes shall be a multiple of alignment.
// - req_addr can be NULL. If not NULL, it must be a multiple of alignment.
// - alignment sets the alignment at which memory shall be allocated.
// It must be a multiple of allocation granularity.
// Returns address of memory or NULL. If req_addr was not NULL, will only return
// req_addr or NULL.
static char* anon_mmap_aligned(size_t bytes, size_t alignment, char* req_addr) {
size_t extra_size = bytes;
if (req_addr == NULL && alignment > 0) {
extra_size += alignment;
}
char* start = (char*) ::mmap(req_addr, extra_size, PROT_NONE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
-1, 0);
if (start == MAP_FAILED) {
start = NULL;
} else {
if (req_addr != NULL) {
if (start != req_addr) {
::munmap(start, extra_size);
start = NULL;
}
} else {
char* const start_aligned = (char*) align_ptr_up(start, alignment);
char* const end_aligned = start_aligned + bytes;
char* const end = start + extra_size;
if (start_aligned > start) {
::munmap(start, start_aligned - start);
}
if (end_aligned < end) {
::munmap(end_aligned, end - end_aligned);
}
start = start_aligned;
}
}
return start;
}
// Don't update _highest_vm_reserved_address, because there might be memory
// regions above addr + size. If so, releasing a memory region only creates
// a hole in the address space, it doesn't help prevent heap-stack collision.
//
static int anon_munmap(char * addr, size_t size) {
return ::munmap(addr, size) == 0;
}
char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
size_t alignment_hint) {
return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
}
bool os::pd_release_memory(char* addr, size_t size) {
return anon_munmap(addr, size);
}
static 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);
}
bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) {
bool result = false;
void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE,
-1, 0);
if (p != MAP_FAILED) {
void *aligned_p = align_ptr_up(p, page_size);
result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
munmap(p, page_size * 2);
}
if (warn && !result) {
warning("TransparentHugePages is not supported by the operating system.");
}
return result;
}
bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
bool result = false;
void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
-1, 0);
if (p != MAP_FAILED) {
// We don't know if this really is a huge page or not.
FILE *fp = fopen("/proc/self/maps", "r");
if (fp) {
while (!feof(fp)) {
char chars[257];
long x = 0;
if (fgets(chars, sizeof(chars), fp)) {
if (sscanf(chars, "%lx-%*x", &x) == 1
&& x == (long)p) {
if (strstr (chars, "hugepage")) {
result = true;
break;
}
}
}
}
fclose(fp);
}
munmap(p, page_size);
}
if (warn && !result) {
warning("HugeTLBFS is not supported by the operating system.");
}
return result;
}
/*
* Set the coredump_filter bits to include largepages in core dump (bit 6)
*
* From the coredump_filter documentation:
*
* - (bit 0) anonymous private memory
* - (bit 1) anonymous shared memory
* - (bit 2) file-backed private memory
* - (bit 3) file-backed shared memory
* - (bit 4) ELF header pages in file-backed private memory areas (it is
* effective only if the bit 2 is cleared)
* - (bit 5) hugetlb private memory
* - (bit 6) hugetlb shared memory
*/
static void set_coredump_filter(void) {
FILE *f;
long cdm;
if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
return;
}
if (fscanf(f, "%lx", &cdm) != 1) {
fclose(f);
return;
}
rewind(f);
if ((cdm & LARGEPAGES_BIT) == 0) {
cdm |= LARGEPAGES_BIT;
fprintf(f, "%#lx", cdm);
}
fclose(f);
}
// Large page support
static size_t _large_page_size = 0;
size_t os::Linux::find_large_page_size() {
size_t large_page_size = 0;
// 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)
ARM_ONLY(2 * M) PPC_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);
}
if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
proper_unit_for_byte_size(large_page_size));
}
return large_page_size;
}
size_t os::Linux::setup_large_page_size() {
_large_page_size = Linux::find_large_page_size();
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;
}
return _large_page_size;
}
bool os::Linux::setup_large_page_type(size_t page_size) {
if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
FLAG_IS_DEFAULT(UseSHM) &&
FLAG_IS_DEFAULT(UseTransparentHugePages)) {
// The type of large pages has not been specified by the user.
// Try UseHugeTLBFS and then UseSHM.
UseHugeTLBFS = UseSHM = true;
// Don't try UseTransparentHugePages since there are known
// performance issues with it turned on. This might change in the future.
UseTransparentHugePages = false;
}
if (UseTransparentHugePages) {
bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
UseHugeTLBFS = false;
UseSHM = false;
return true;
}
UseTransparentHugePages = false;
}
if (UseHugeTLBFS) {
bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
UseSHM = false;
return true;
}
UseHugeTLBFS = false;
}
return UseSHM;
}
void os::large_page_init() {
if (!UseLargePages &&
!UseTransparentHugePages &&
!UseHugeTLBFS &&
!UseSHM) {
// Not using large pages.
return;
}
if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
// The user explicitly turned off large pages.
// Ignore the rest of the large pages flags.
UseTransparentHugePages = false;
UseHugeTLBFS = false;
UseSHM = false;
return;
}
size_t large_page_size = Linux::setup_large_page_size();
UseLargePages = Linux::setup_large_page_type(large_page_size);
set_coredump_filter();
}
#ifndef SHM_HUGETLB
#define SHM_HUGETLB 04000
#endif
#define shm_warning_format(format, ...) \
do { \
if (UseLargePages && \
(!FLAG_IS_DEFAULT(UseLargePages) || \
!FLAG_IS_DEFAULT(UseSHM) || \
!FLAG_IS_DEFAULT(LargePageSizeInBytes))) { \
warning(format, __VA_ARGS__); \
} \
} while (0)
#define shm_warning(str) shm_warning_format("%s", str)
#define shm_warning_with_errno(str) \
do { \
int err = errno; \
shm_warning_format(str " (error = %d)", err); \
} while (0)
static char* shmat_with_alignment(int shmid, size_t bytes, size_t alignment) {
assert(is_size_aligned(bytes, alignment), "Must be divisible by the alignment");
if (!is_size_aligned(alignment, SHMLBA)) {
assert(false, "Code below assumes that alignment is at least SHMLBA aligned");
return NULL;
}
// To ensure that we get 'alignment' aligned memory from shmat,
// we pre-reserve aligned virtual memory and then attach to that.
char* pre_reserved_addr = anon_mmap_aligned(bytes, alignment, NULL);
if (pre_reserved_addr == NULL) {
// Couldn't pre-reserve aligned memory.
shm_warning("Failed to pre-reserve aligned memory for shmat.");
return NULL;
}
// SHM_REMAP is needed to allow shmat to map over an existing mapping.
char* addr = (char*)shmat(shmid, pre_reserved_addr, SHM_REMAP);
if ((intptr_t)addr == -1) {
int err = errno;
shm_warning_with_errno("Failed to attach shared memory.");
assert(err != EACCES, "Unexpected error");
assert(err != EIDRM, "Unexpected error");
assert(err != EINVAL, "Unexpected error");
// Since we don't know if the kernel unmapped the pre-reserved memory area
// we can't unmap it, since that would potentially unmap memory that was
// mapped from other threads.
return NULL;
}
return addr;
}
static char* shmat_at_address(int shmid, char* req_addr) {
if (!is_ptr_aligned(req_addr, SHMLBA)) {
assert(false, "Requested address needs to be SHMLBA aligned");
return NULL;
}
char* addr = (char*)shmat(shmid, req_addr, 0);
if ((intptr_t)addr == -1) {
shm_warning_with_errno("Failed to attach shared memory.");
return NULL;
}
return addr;
}
static char* shmat_large_pages(int shmid, size_t bytes, size_t alignment, char* req_addr) {
// If a req_addr has been provided, we assume that the caller has already aligned the address.
if (req_addr != NULL) {
assert(is_ptr_aligned(req_addr, os::large_page_size()), "Must be divisible by the large page size");
assert(is_ptr_aligned(req_addr, alignment), "Must be divisible by given alignment");
return shmat_at_address(shmid, req_addr);
}
// Since shmid has been setup with SHM_HUGETLB, shmat will automatically
// return large page size aligned memory addresses when req_addr == NULL.
// However, if the alignment is larger than the large page size, we have
// to manually ensure that the memory returned is 'alignment' aligned.
if (alignment > os::large_page_size()) {
assert(is_size_aligned(alignment, os::large_page_size()), "Must be divisible by the large page size");
return shmat_with_alignment(shmid, bytes, alignment);
} else {
return shmat_at_address(shmid, NULL);
}
}
char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, 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 && UseSHM, "only for SHM large pages");
assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
assert(is_ptr_aligned(req_addr, alignment), "Unaligned address");
if (!is_size_aligned(bytes, os::large_page_size())) {
return NULL; // Fallback to small pages.
}
// Create a large shared memory region to attach to based on size.
// Currently, size is the total size of the heap.
int shmid = shmget(IPC_PRIVATE, 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".
shm_warning_with_errno("Failed to reserve shared memory.");
return NULL;
}
// Attach to the region.
char* addr = shmat_large_pages(shmid, bytes, alignment, req_addr);
// 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);
return addr;
}
static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) {
assert(error == ENOMEM, "Only expect to fail if no memory is available");
bool warn_on_failure = UseLargePages &&
(!FLAG_IS_DEFAULT(UseLargePages) ||
!FLAG_IS_DEFAULT(UseHugeTLBFS) ||
!FLAG_IS_DEFAULT(LargePageSizeInBytes));
if (warn_on_failure) {
char msg[128];
jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
warning("%s", msg);
}
}
char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) {
assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
char* addr = (char*)::mmap(req_addr, bytes, prot,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
-1, 0);
if (addr == MAP_FAILED) {
warn_on_large_pages_failure(req_addr, bytes, errno);
return NULL;
}
assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
return addr;
}
// Reserve memory using mmap(MAP_HUGETLB).
// - bytes shall be a multiple of alignment.
// - req_addr can be NULL. If not NULL, it must be a multiple of alignment.
// - alignment sets the alignment at which memory shall be allocated.
// It must be a multiple of allocation granularity.
// Returns address of memory or NULL. If req_addr was not NULL, will only return
// req_addr or NULL.
char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) {
size_t large_page_size = os::large_page_size();
assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
assert(is_ptr_aligned(req_addr, alignment), "Must be");
assert(is_size_aligned(bytes, alignment), "Must be");
// First reserve - but not commit - the address range in small pages.
char* const start = anon_mmap_aligned(bytes, alignment, req_addr);
if (start == NULL) {
return NULL;
}
assert(is_ptr_aligned(start, alignment), "Must be");
char* end = start + bytes;
// Find the regions of the allocated chunk that can be promoted to large pages.
char* lp_start = (char*)align_ptr_up(start, large_page_size);
char* lp_end = (char*)align_ptr_down(end, large_page_size);
size_t lp_bytes = lp_end - lp_start;
assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
if (lp_bytes == 0) {
// The mapped region doesn't even span the start and the end of a large page.
// Fall back to allocate a non-special area.
::munmap(start, end - start);
return NULL;
}
int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
void* result;
// Commit small-paged leading area.
if (start != lp_start) {
result = ::mmap(start, lp_start - start, prot,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
-1, 0);
if (result == MAP_FAILED) {
::munmap(lp_start, end - lp_start);
return NULL;
}
}
// Commit large-paged area.
result = ::mmap(lp_start, lp_bytes, prot,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
-1, 0);
if (result == MAP_FAILED) {
warn_on_large_pages_failure(lp_start, lp_bytes, errno);
// If the mmap above fails, the large pages region will be unmapped and we
// have regions before and after with small pages. Release these regions.
//
// | mapped | unmapped | mapped |
// ^ ^ ^ ^
// start lp_start lp_end end
//
::munmap(start, lp_start - start);
::munmap(lp_end, end - lp_end);
return NULL;
}
// Commit small-paged trailing area.
if (lp_end != end) {
result = ::mmap(lp_end, end - lp_end, prot,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
-1, 0);
if (result == MAP_FAILED) {
::munmap(start, lp_end - start);
return NULL;
}
}
return start;
}
char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) {
assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
assert(is_ptr_aligned(req_addr, alignment), "Must be");
assert(is_size_aligned(alignment, os::vm_allocation_granularity()), "Must be");
assert(is_power_of_2(os::large_page_size()), "Must be");
assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
} else {
return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
}
}
char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) {
assert(UseLargePages, "only for large pages");
char* addr;
if (UseSHM) {
addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
} else {
assert(UseHugeTLBFS, "must be");
addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
}
if (addr != NULL) {
if (UseNUMAInterleaving) {
numa_make_global(addr, bytes);
}
// The memory is committed
MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
}
return addr;
}
bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
// detaching the SHM segment will also delete it, see reserve_memory_special_shm()
return shmdt(base) == 0;
}
bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
return pd_release_memory(base, bytes);
}
bool os::release_memory_special(char* base, size_t bytes) {
bool res;
if (MemTracker::tracking_level() > NMT_minimal) {
Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
res = os::Linux::release_memory_special_impl(base, bytes);
if (res) {
tkr.record((address)base, bytes);
}
} else {
res = os::Linux::release_memory_special_impl(base, bytes);
}
return res;
}
bool os::Linux::release_memory_special_impl(char* base, size_t bytes) {
assert(UseLargePages, "only for large pages");
bool res;
if (UseSHM) {
res = os::Linux::release_memory_special_shm(base, bytes);
} else {
assert(UseHugeTLBFS, "must be");
res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
}
return res;
}
size_t os::large_page_size() {
return _large_page_size;
}
// With SysV SHM the entire memory region must be allocated as shared
// memory.
// HugeTLBFS allows application to commit large page memory on demand.
// However, when committing memory with HugeTLBFS fails, the region
// that was supposed to be committed will lose the old reservation
// and allow other threads to steal that memory region. Because of this
// behavior we can't commit HugeTLBFS memory.
bool os::can_commit_large_page_memory() {
return UseTransparentHugePages;
}
bool os::can_execute_large_page_memory() {
return UseTransparentHugePages || UseHugeTLBFS;
}
// Reserve memory at an arbitrary address, only if that area is
// available (and not reserved for something else).
char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
const int max_tries = 10;
char* base[max_tries];
size_t size[max_tries];
const size_t gap = 0x000000;
// Assert only that the size is a multiple of the page size, since
// that's all that mmap requires, and since that's all we really know
// about at this low abstraction level. If we need higher alignment,
// we can either pass an alignment to this method or verify alignment
// in one of the methods further up the call chain. See bug 5044738.
assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
// Repeatedly allocate blocks until the block is allocated at the
// right spot. Give up after max_tries. Note that reserve_memory() will
// automatically update _highest_vm_reserved_address if the call is
// successful. The variable tracks the highest memory address every reserved
// by JVM. It is used to detect heap-stack collision if running with
// fixed-stack 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.
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_MILLISEC;
}
if(millis <= 0) {
return OS_OK;
}
prevtime = newtime;
{
assert(thread->is_Java_thread(), "sanity check");
JavaThread *jt = (JavaThread *) thread;
ThreadBlockInVM tbivm(jt);
OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
jt->set_suspend_equivalent();
// cleared by handle_special_suspend_equivalent_condition() or
// java_suspend_self() via check_and_wait_while_suspended()
slp->park(millis);
// were we externally suspended while we were waiting?
jt->check_and_wait_while_suspended();
}
}
} else {
OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
jlong prevtime = javaTimeNanos();
for (;;) {
// It'd be nice to avoid the back-to-back javaTimeNanos() calls on
// the 1st iteration ...
jlong newtime = javaTimeNanos();
if (newtime - prevtime < 0) {
// time moving backwards, should only happen if no monotonic clock
// not a guarantee() because JVM should not abort on kernel/glibc bugs
assert(!Linux::supports_monotonic_clock(), "time moving backwards");
} else {
millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
}
if(millis <= 0) break ;
prevtime = newtime;
slp->park(millis);
}
return OS_OK ;
}
}
//
// Short sleep, direct OS call.
//
// Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
// sched_yield(2) will actually give up the CPU:
//
// * Alone on this pariticular CPU, keeps running.
// * Before the introduction of "skip_buddy" with "compat_yield" disabled
// (pre 2.6.39).
//
// So calling this with 0 is an alternative.
//
void os::naked_short_sleep(jlong ms) {
struct timespec req;
assert(ms < 1000, "Un-interruptable sleep, short time use only");
req.tv_sec = 0;
if (ms > 0) {
req.tv_nsec = (ms % 1000) * 1000000;
}
else {
req.tv_nsec = 1;
}
nanosleep(&req, NULL);
return;
}
// Sleep forever; naked call to OS-specific sleep; use with CAUTION
void os::infinite_sleep() {
while (true) { // sleep forever ...
::sleep(100); // ... 100 seconds at a time
}
}
// Used to convert frequent JVM_Yield() to nops
bool os::dont_yield() {
return DontYieldALot;
}
void os::yield() {
sched_yield();
}
os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
void os::yield_all(int attempts) {
// Yields to all threads, including threads with lower priorities
// Threads on 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[CriticalPriority + 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
-5 // 11 CriticalPriority
};
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;
}
}
if (UseCriticalJavaThreadPriority) {
os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
}
return 0;
}
OSReturn os::set_native_priority(Thread* thread, int newpri) {
if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
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);
}
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 and JavaThreads (PC sampling)
//
static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
// Save and restore errno to avoid confusing native code with EINTR
// after sigsuspend.
int old_errno = errno;
Thread* thread = Thread::current();
OSThread* osthread = thread->osthread();
assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
os::SuspendResume::State current = osthread->sr.state();
if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
suspend_save_context(osthread, siginfo, context);
// attempt to switch the state, we assume we had a SUSPEND_REQUEST
os::SuspendResume::State state = osthread->sr.suspended();
if (state == os::SuspendResume::SR_SUSPENDED) {
sigset_t suspend_set; // signals for sigsuspend()
// get current set of blocked signals and unblock resume signal
pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
sigdelset(&suspend_set, SR_signum);
sr_semaphore.signal();
// wait here until we are resumed
while (1) {
sigsuspend(&suspend_set);
os::SuspendResume::State result = osthread->sr.running();
if (result == os::SuspendResume::SR_RUNNING) {
sr_semaphore.signal();
break;
}
}
} else if (state == os::SuspendResume::SR_RUNNING) {
// request was cancelled, continue
} else {
ShouldNotReachHere();
}
resume_clear_context(osthread);
} else if (current == os::SuspendResume::SR_RUNNING) {
// request was cancelled, continue
} else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
// ignore
} else {
// ignore
}
errno = old_errno;
}
static int SR_initialize() {
struct sigaction act;
char *s;
/* Get signal number to use for suspend/resume */
if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
int sig = ::strtol(s, 0, 10);
if (sig > 0 || sig < _NSIG) {
SR_signum = sig;
}
}
assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
"SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
sigemptyset(&SR_sigset);
sigaddset(&SR_sigset, SR_signum);
/* Set up signal handler for suspend/resume */
act.sa_flags = SA_RESTART|SA_SIGINFO;
act.sa_handler = (void (*)(int)) SR_handler;
// SR_signum is blocked by default.
// 4528190 - We also need to block pthread restart signal (32 on all
// supported 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_notify(OSThread* osthread) {
int status = pthread_kill(osthread->pthread_id(), SR_signum);
assert_status(status == 0, status, "pthread_kill");
return status;
}
// "Randomly" selected value for how long we want to spin
// before bailing out on suspending a thread, also how often
// we send a signal to a thread we want to resume
static const int RANDOMLY_LARGE_INTEGER = 1000000;
static const int RANDOMLY_LARGE_INTEGER2 = 100;
// returns true on success and false on error - really an error is fatal
// but this seems the normal response to library errors
static bool do_suspend(OSThread* osthread) {
assert(osthread->sr.is_running(), "thread should be running");
assert(!sr_semaphore.trywait(), "semaphore has invalid state");
// mark as suspended and send signal
if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
// failed to switch, state wasn't running?
ShouldNotReachHere();
return false;
}
if (sr_notify(osthread) != 0) {
ShouldNotReachHere();
}
// managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
while (true) {
if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
break;
} else {
// timeout
os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
if (cancelled == os::SuspendResume::SR_RUNNING) {
return false;
} else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
// make sure that we consume the signal on the semaphore as well
sr_semaphore.wait();
break;
} else {
ShouldNotReachHere();
return false;
}
}
}
guarantee(osthread->sr.is_suspended(), "Must be suspended");
return true;
}
static void do_resume(OSThread* osthread) {
assert(osthread->sr.is_suspended(), "thread should be suspended");
assert(!sr_semaphore.trywait(), "invalid semaphore state");
if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
// failed to switch to WAKEUP_REQUEST
ShouldNotReachHere();
return;
}
while (true) {
if (sr_notify(osthread) == 0) {
if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
if (osthread->sr.is_running()) {
return;
}
}
} else {
ShouldNotReachHere();
}
}
guarantee(osthread->sr.is_running(), "Must be running!");
}
////////////////////////////////////////////////////////////////////////////////
// interrupt support
void os::interrupt(Thread* thread) {
assert(Thread::current() == thread || Threads_lock->owned_by_self(),
"possibility of dangling Thread pointer");
OSThread* osthread = thread->osthread();
if (!osthread->interrupted()) {
osthread->set_interrupted(true);
// More than one thread can get here with the same value of osthread,
// resulting in multiple notifications. We do, however, want the store
// to interrupted() to be visible to other threads before we execute unpark().
OrderAccess::fence();
ParkEvent * const slp = thread->_SleepEvent ;
if (slp != NULL) slp->unpark() ;
}
// For JSR166. Unpark even if interrupt status already was set
if (thread->is_Java_thread())
((JavaThread*)thread)->parker()->unpark();
ParkEvent * ev = thread->_ParkEvent ;
if (ev != NULL) ev->unpark() ;
}
bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
assert(Thread::current() == thread || Threads_lock->owned_by_self(),
"possibility of dangling Thread pointer");
OSThread* osthread = thread->osthread();
bool interrupted = osthread->interrupted();
if (interrupted && clear_interrupted) {
osthread->set_interrupted(false);
// consider thread->_SleepEvent->reset() ... optional optimization
}
return interrupted;
}
///////////////////////////////////////////////////////////////////////////////////
// signal handling (except suspend/resume)
// This routine may be used by user applications as a "hook" to catch signals.
// The user-defined signal handler must pass unrecognized signals to this
// routine, and if it returns true (non-zero), then the signal handler must
// return immediately. If the flag "abort_if_unrecognized" is true, then this
// routine will never retun false (zero), but instead will execute a VM panic
// routine kill the process.
//
// If this routine returns false, it is OK to call it again. This allows
// the user-defined signal handler to perform checks either before or after
// the VM performs its own checks. Naturally, the user code would be making
// a serious error if it tried to handle an exception (such as a null check
// or breakpoint) that the VM was generating for its own correct operation.
//
// This routine may recognize any of the following kinds of signals:
// SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
// It should be consulted by handlers for any of those signals.
//
// The caller of this routine must pass in the three arguments supplied
// to the function referred to in the "sa_sigaction" (not the "sa_handler")
// field of the structure passed to sigaction(). This routine assumes that
// the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
//
// Note that the VM will print warnings if it detects conflicting signal
// handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
//
extern "C" JNIEXPORT int
JVM_handle_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");
int orig_errno = errno; // Preserve errno value over signal handler.
JVM_handle_linux_signal(sig, info, uc, true);
errno = orig_errno;
}
// 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 = NULL;
sa_sigaction_t sa = NULL;
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 {
fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
"%#lx for signal %d.", (long)oldhand, sig));
}
}
struct sigaction sigAct;
sigfillset(&(sigAct.sa_mask));
sigAct.sa_handler = SIG_DFL;
if (!set_installed) {
sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
} else {
sigAct.sa_sigaction = signalHandler;
sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
}
// 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);
#if defined(PPC64)
set_signal_handler(SIGTRAP, true);
#endif
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.
// Log that signal checking is off only if -verbose:jni is specified.
if (CheckJNICalls) {
if (libjsig_is_loaded) {
if (PrintJNIResolving) {
tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
}
check_signals = false;
}
if (AllowUserSignalHandlers) {
if (PrintJNIResolving) {
tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
}
check_signals = false;
}
}
}
}
// 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 * NANOSECS_PER_SEC) + 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 = 0;
bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
if (found) {
// skip directory names
const char *p1, *p2;
p1 = buf;
size_t len = strlen(os::file_separator());
while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
} else {
jio_snprintf(buf, buflen, PTR_FORMAT, handler);
}
return buf;
}
static void print_signal_handler(outputStream* st, int sig,
char* buf, size_t buflen) {
struct sigaction sa;
sigaction(sig, NULL, &sa);
// See comment for SIGNIFICANT_SIGNAL_MASK define
sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
st->print("%s: ", os::exception_name(sig, buf, buflen));
address handler = (sa.sa_flags & SA_SIGINFO)
? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
: CAST_FROM_FN_PTR(address, sa.sa_handler);
if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
st->print("SIG_DFL");
} else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
st->print("SIG_IGN");
} else {
st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
}
st->print(", sa_mask[0]=");
os::Posix::print_signal_set_short(st, &sa.sa_mask);
address rh = VMError::get_resetted_sighandler(sig);
// May be, handler was resetted by VMError?
if(rh != NULL) {
handler = rh;
sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
}
st->print(", sa_flags=");
os::Posix::print_sa_flags(st, sa.sa_flags);
// Check: is it our handler?
if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
// It is our signal handler
// check for flags, reset system-used one!
if((int)sa.sa_flags != os::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);
#if defined(PPC64)
DO_SIGNAL_CHECK(SIGTRAP);
#endif
// 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);
// Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
exception_name(sig, buf, O_BUFLEN));
}
} else if(os::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) {
fatal(err_msg("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 = javaTimeNanos();
// pthread_condattr initialization for monotonic clock
int status;
pthread_condattr_t* _condattr = os::Linux::condAttr();
if ((status = pthread_condattr_init(_condattr)) != 0) {
fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
}
// Only set the clock if CLOCK_MONOTONIC is available
if (Linux::supports_monotonic_clock()) {
if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
if (status == EINVAL) {
warning("Unable to use monotonic clock with relative timed-waits" \
" - changes to the time-of-day clock may have adverse affects");
} else {
fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
}
}
}
// else it defaults to CLOCK_REALTIME
pthread_mutex_init(&dl_mutex, NULL);
// If the pagesize of the VM is greater than 8K determine the appropriate
// number of initial guard pages. The user can change this with the
// command line arguments, if needed.
if (vm_page_size() > (int)Linux::vm_default_page_size()) {
StackYellowPages = 1;
StackRedPages = 1;
StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
}
}
// 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 != MAP_FAILED, "mmap Failed for memory serialize page");
os::set_memory_serialize_page( mem_serialize_page );
#ifndef PRODUCT
if(Verbose && PrintMiscellaneous)
tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
#endif
}
// initialize suspend/resume support - must do this before signal_sets_init()
if (SR_initialize() != 0) {
perror("SR_initialize failed");
return JNI_ERR;
}
Linux::signal_sets_init();
Linux::install_signal_handlers();
// Check minimum allowable stack size for thread creation and to initialize
// the java system classes, including StackOverflowError - depends on page
// size. Add a page for compiler2 recursion in main thread.
// Add in 2*BytesPerWord times page size to account for VM stack during
// class initialization depending on 32 or 64 bit VM.
os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
(size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
(2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
size_t threadStackSizeInBytes = ThreadStackSize * K;
if (threadStackSizeInBytes != 0 &&
threadStackSizeInBytes < os::Linux::min_stack_allowed) {
tty->print_cr("\nThe stack size specified is too small, "
"Specify at least %dk",
os::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());
#if defined(IA32)
workaround_expand_exec_shield_cs_limit();
#endif
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;
}
}
// With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
// we can make the adaptive lgrp chunk resizing work. If the user specified
// both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
// disable adaptive resizing.
if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
if (FLAG_IS_DEFAULT(UseNUMA)) {
UseNUMA = false;
} else {
if (FLAG_IS_DEFAULT(UseLargePages) &&
FLAG_IS_DEFAULT(UseSHM) &&
FLAG_IS_DEFAULT(UseHugeTLBFS)) {
UseLargePages = false;
} else {
warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
UseAdaptiveSizePolicy = false;
UseAdaptiveNUMAChunkSizing = 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));
// 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::init_2 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");
}
};
static int os_cpu_count(const cpu_set_t* cpus) {
int count = 0;
// only look up to the number of configured processors
for (int i = 0; i < os::processor_count(); i++) {
if (CPU_ISSET(i, cpus)) {
count++;
}
}
return count;
}
// Get the current number of available processors for this process.
// This value can change at any time during a process's lifetime.
// sched_getaffinity gives an accurate answer as it accounts for cpusets.
// If anything goes wrong we fallback to returning the number of online
// processors - which can be greater than the number available to the process.
int os::active_processor_count() {
cpu_set_t cpus; // can represent at most 1024 (CPU_SETSIZE) processors
int cpus_size = sizeof(cpu_set_t);
int cpu_count = 0;
// pid 0 means the current thread - which we have to assume represents the process
if (sched_getaffinity(0, cpus_size, &cpus) == 0) {
cpu_count = os_cpu_count(&cpus);
if (PrintActiveCpus) {
tty->print_cr("active_processor_count: sched_getaffinity processor count: %d", cpu_count);
}
}
else {
cpu_count = ::sysconf(_SC_NPROCESSORS_ONLN);
warning("sched_getaffinity failed (%s)- using online processor count (%d) "
"which may exceed available processors", strerror(errno), cpu_count);
}
assert(cpu_count > 0 && cpu_count <= processor_count(), "sanity check");
return cpu_count;
}
void os::set_native_thread_name(const char *name) {
// Not yet implemented.
return;
}
bool os::distribute_processes(uint length, uint* distribution) {
// Not yet implemented.
return false;
}
bool os::bind_to_processor(uint processor_id) {
// Not yet implemented.
return false;
}
///
void os::SuspendedThreadTask::internal_do_task() {
if (do_suspend(_thread->osthread())) {
SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
do_task(context);
do_resume(_thread->osthread());
}
}
class PcFetcher : public os::SuspendedThreadTask {
public:
PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
ExtendedPC result();
protected:
void do_task(const os::SuspendedThreadTaskContext& context);
private:
ExtendedPC _epc;
};
ExtendedPC PcFetcher::result() {
guarantee(is_done(), "task is not done yet.");
return _epc;
}
void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
Thread* thread = context.thread();
OSThread* osthread = thread->osthread();
if (osthread->ucontext() != NULL) {
_epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
} else {
// NULL context is unexpected, double-check this is the VMThread
guarantee(thread->is_VM_thread(), "can only be called for VMThread");
}
}
// Suspends the target using the signal mechanism and then grabs the PC before
// resuming the target. Used by the flat-profiler only
ExtendedPC os::get_thread_pc(Thread* thread) {
// Make sure that it is called by the watcher for the VMThread
assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
assert(thread->is_VM_thread(), "Can only be called for VMThread");
PcFetcher fetcher(thread);
fetcher.run();
return fetcher.result();
}
int os::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 {
// 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();
int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
set_fpu_control_word(fpu);
return status;
}
}
////////////////////////////////////////////////////////////////////////////////
// debug support
bool os::find(address addr, outputStream* st) {
Dl_info dlinfo;
memset(&dlinfo, 0, sizeof(dlinfo));
if (dladdr(addr, &dlinfo) != 0) {
st->print(PTR_FORMAT ": ", addr);
if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
st->print("%s+%#x", dlinfo.dli_sname,
addr - (intptr_t)dlinfo.dli_saddr);
} else if (dlinfo.dli_fbase != NULL) {
st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
} else {
st->print("<absolute address>");
}
if (dlinfo.dli_fname != NULL) {
st->print(" in %s", dlinfo.dli_fname);
}
if (dlinfo.dli_fbase != NULL) {
st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
}
st->cr();
if (Verbose) {
// decode some bytes around the PC
address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
address lowest = (address) dlinfo.dli_sname;
if (!lowest) lowest = (address) dlinfo.dli_fbase;
if (begin < lowest) begin = lowest;
Dl_info dlinfo2;
if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
&& end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
end = (address) dlinfo2.dli_saddr;
Disassembler::decode(begin, end, st);
}
return true;
}
return false;
}
////////////////////////////////////////////////////////////////////////////////
// misc
// This does not do anything on 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;
}
os::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;
}
// This code originates from JDK's sysOpen and open64_w
// from src/solaris/hpi/src/system_md.c
#ifndef O_DELETE
#define O_DELETE 0x10000
#endif
// Open a file. Unlink the file immediately after open returns
// if the specified oflag has the O_DELETE flag set.
// O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
int os::open(const char *path, int oflag, int mode) {
if (strlen(path) > MAX_PATH - 1) {
errno = ENAMETOOLONG;
return -1;
}
int fd;
int o_delete = (oflag & O_DELETE);
oflag = oflag & ~O_DELETE;
fd = ::open64(path, oflag, mode);
if (fd == -1) return -1;
//If the open succeeded, the file might still be a directory
{
struct stat64 buf64;
int ret = ::fstat64(fd, &buf64);
int st_mode = buf64.st_mode;
if (ret != -1) {
if ((st_mode & S_IFMT) == S_IFDIR) {
errno = EISDIR;
::close(fd);
return -1;
}
} else {
::close(fd);
return -1;
}
}
/*
* All file descriptors that are opened in the JVM and not
* specifically destined for a subprocess should have the
* close-on-exec flag set. If we don't set it, then careless 3rd
* party native code might fork and exec without closing all
* appropriate file descriptors (e.g. as we do in closeDescriptors in
* UNIXProcess.c), and this in turn might:
*
* - cause end-of-file to fail to be detected on some file
* descriptors, resulting in mysterious hangs, or
*
* - might cause an fopen in the subprocess to fail on a system
* suffering from bug 1085341.
*
* (Yes, the default setting of the close-on-exec flag is a Unix
* design flaw)
*
* See:
* 1085341: 32-bit stdio routines should support file descriptors >255
* 4843136: (process) pipe file descriptor from Runtime.exec not being closed
* 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
*/
#ifdef FD_CLOEXEC
{
int flags = ::fcntl(fd, F_GETFD);
if (flags != -1)
::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
}
#endif
if (o_delete != 0) {
::unlink(path);
}
return fd;
}
// create binary file, rewriting existing file if required
int os::create_binary_file(const char* path, bool rewrite_existing) {
int oflags = O_WRONLY | O_CREAT;
if (!rewrite_existing) {
oflags |= O_EXCL;
}
return ::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);
}
// This code originates from JDK's sysAvailable
// from src/solaris/hpi/src/native_threads/src/sys_api_td.c
int os::available(int fd, jlong *bytes) {
jlong cur, end;
int mode;
struct stat64 buf64;
if (::fstat64(fd, &buf64) >= 0) {
mode = buf64.st_mode;
if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
/*
* XXX: is the following call interruptible? If so, this might
* need to go through the INTERRUPT_IO() wrapper as for other
* blocking, interruptible calls in this file.
*/
int n;
if (::ioctl(fd, FIONREAD, &n) >= 0) {
*bytes = n;
return 1;
}
}
}
if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
return 0;
} else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
return 0;
} else if (::lseek64(fd, cur, SEEK_SET) == -1) {
return 0;
}
*bytes = end - cur;
return 1;
}
int os::socket_available(int fd, jint *pbytes) {
// Linux doc says EINTR not returned, unlike Solaris
int ret = ::ioctl(fd, FIONREAD, pbytes);
//%% note ioctl can return 0 when successful, JVM_SocketAvailable
// is expected to return 0 on failure and 1 on success to the jdk.
return (ret < 0) ? 0 : 1;
}
// Map a block of memory.
char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
char *addr, size_t bytes, bool read_only,
bool allow_exec) {
int prot;
int flags = MAP_PRIVATE;
if (read_only) {
prot = PROT_READ;
} else {
prot = PROT_READ | PROT_WRITE;
}
if (allow_exec) {
prot |= PROT_EXEC;
}
if (addr != NULL) {
flags |= MAP_FIXED;
}
char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
fd, file_offset);
if (mapped_address == MAP_FAILED) {
return NULL;
}
return mapped_address;
}
// Remap a block of memory.
char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
char *addr, size_t bytes, bool read_only,
bool allow_exec) {
// same as map_memory() on this OS
return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
allow_exec);
}
// Unmap a block of memory.
bool os::pd_unmap_memory(char* addr, size_t bytes) {
return munmap(addr, bytes) == 0;
}
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.
//
PRAGMA_DIAG_PUSH
PRAGMA_FORMAT_NONLITERAL_IGNORED
static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
static bool proc_task_unchecked = true;
static const char *proc_stat_path = "/proc/%d/stat";
pid_t tid = thread->osthread()->thread_id();
char *s;
char stat[2048];
int statlen;
char proc_name[64];
int count;
long sys_time, user_time;
char cdummy;
int idummy;
long ldummy;
FILE *fp;
// 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 possibly can be cases where there is no directory
// /proc/self/task, 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, ')');
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",
&cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
&ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
&user_time, &sys_time);
if ( count != 13 ) 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);
}
}
PRAGMA_DIAG_POP
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);
}
}
// 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;
jlong seconds = millis / 1000;
millis %= 1000;
if (seconds > 50000000) { // see man cond_timedwait(3T)
seconds = 50000000;
}
if (os::Linux::supports_monotonic_clock()) {
struct timespec now;
int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
assert_status(status == 0, status, "clock_gettime");
abstime->tv_sec = now.tv_sec + seconds;
long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
if (nanos >= NANOSECS_PER_SEC) {
abstime->tv_sec += 1;
nanos -= NANOSECS_PER_SEC;
}
abstime->tv_nsec = nanos;
} else {
struct timeval now;
int status = gettimeofday(&now, NULL);
assert(status == 0, "gettimeofday");
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 ;
_Event = 0 ;
status = pthread_mutex_unlock(_mutex);
assert_status(status == 0, status, "mutex_unlock");
// Paranoia to ensure our locked and lock-free paths interact
// correctly with each other.
OrderAccess::fence();
}
guarantee (_Event >= 0, "invariant") ;
}
int os::PlatformEvent::park(jlong millis) {
guarantee (_nParked == 0, "invariant") ;
int v ;
for (;;) {
v = _Event ;
if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
}
guarantee (v >= 0, "invariant") ;
if (v != 0) return OS_OK ;
// We do this the hard way, by blocking the thread.
// Consider enforcing a minimum timeout value.
struct timespec abst;
compute_abstime(&abst, millis);
int ret = OS_TIMEOUT;
int status = pthread_mutex_lock(_mutex);
assert_status(status == 0, status, "mutex_lock");
guarantee (_nParked == 0, "invariant") ;
++_nParked ;
// Object.wait(timo) will return because of
// (a) notification
// (b) timeout
// (c) thread.interrupt
//
// Thread.interrupt and object.notify{All} both call Event::set.
// That is, we treat thread.interrupt as a special case of notification.
// The underlying Solaris implementation, cond_timedwait, admits
// spurious/premature wakeups, but the JLS/JVM spec prevents the
// JVM from making those visible to Java code. As such, we must
// filter out spurious wakeups. We assume all ETIME returns are valid.
//
// TODO: properly differentiate simultaneous notify+interrupt.
// In that case, we should propagate the notify to another waiter.
while (_Event < 0) {
status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
if (status != 0 && WorkAroundNPTLTimedWaitHang) {
pthread_cond_destroy (_cond);
pthread_cond_init (_cond, os::Linux::condAttr()) ;
}
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") ;
// Paranoia to ensure our locked and lock-free paths interact
// correctly with each other.
OrderAccess::fence();
return ret;
}
void os::PlatformEvent::unpark() {
// Transitions for _Event:
// 0 :=> 1
// 1 :=> 1
// -1 :=> either 0 or 1; must signal target thread
// That is, we can safely transition _Event from -1 to either
// 0 or 1. Forcing 1 is slightly more efficient for back-to-back
// unpark() calls.
// See also: "Semaphores in Plan 9" by Mullender & Cox
//
// Note: Forcing a transition from "-1" to "1" on an unpark() means
// that it will take two back-to-back park() calls for the owning
// thread to block. This has the benefit of forcing a spurious return
// from the first park() call after an unpark() call which will help
// shake out uses of park() and unpark() without condition variables.
if (Atomic::xchg(1, &_Event) >= 0) return;
// Wait for the thread associated with the event to vacate
int status = pthread_mutex_lock(_mutex);
assert_status(status == 0, status, "mutex_lock");
int AnyWaiters = _nParked;
assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
AnyWaiters = 0;
pthread_cond_signal(_cond);
}
status = pthread_mutex_unlock(_mutex);
assert_status(status == 0, status, "mutex_unlock");
if (AnyWaiters != 0) {
status = pthread_cond_signal(_cond);
assert_status(status == 0, status, "cond_signal");
}
// Note that we signal() _after dropping the lock for "immortal" Events.
// This is safe and avoids a common class of futile wakeups. In rare
// circumstances this can cause a thread to return prematurely from
// cond_{timed}wait() but the spurious wakeup is benign and the victim will
// simply re-test the condition and re-park itself.
}
// JSR166
// -------------------------------------------------------
/*
* The solaris and 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.
*/
/*
* 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");
time_t max_secs = 0;
if (!os::Linux::supports_monotonic_clock() || isAbsolute) {
struct timeval now;
int status = gettimeofday(&now, NULL);
assert(status == 0, "gettimeofday");
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
}
}
}
} else {
// must be relative using monotonic clock
struct timespec now;
int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
assert_status(status == 0, status, "clock_gettime");
max_secs = now.tv_sec + MAX_SECS;
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_nsec;
if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
absTime->tv_nsec -= NANOSECS_PER_SEC;
++absTime->tv_sec; // note: this must be <= max_secs
}
}
}
assert(absTime->tv_sec >= 0, "tv_sec < 0");
assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
}
void Parker::park(bool isAbsolute, jlong time) {
// Ideally we'd do something useful while spinning, such
// as calling unpackTime().
// Optional fast-path check:
// Return immediately if a permit is available.
// We depend on Atomic::xchg() having full barrier semantics
// since we are doing a lock-free update to _counter.
if (Atomic::xchg(0, &_counter) > 0) return;
Thread* thread = Thread::current();
assert(thread->is_Java_thread(), "Must be JavaThread");
JavaThread *jt = (JavaThread *)thread;
// Optional optimization -- avoid state transitions if there's an interrupt pending.
// Check interrupt before trying to wait
if (Thread::is_interrupted(thread, false)) {
return;
}
// Next, demultiplex/decode time arguments
timespec absTime;
if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
return;
}
if (time > 0) {
unpackTime(&absTime, isAbsolute, time);
}
// Enter safepoint region
// Beware of deadlocks such as 6317397.
// The per-thread Parker:: mutex is a classic leaf-lock.
// In particular a thread must never block on the Threads_lock while
// holding the Parker:: mutex. If safepoints are pending both the
// the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
ThreadBlockInVM tbivm(jt);
// Don't wait if cannot get lock since interference arises from
// unblocking. Also. check interrupt before trying wait
if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
return;
}
int status ;
if (_counter > 0) { // no wait needed
_counter = 0;
status = pthread_mutex_unlock(_mutex);
assert (status == 0, "invariant") ;
// Paranoia to ensure our locked and lock-free paths interact
// correctly with each other and Java-level accesses.
OrderAccess::fence();
return;
}
#ifdef ASSERT
// Don't catch signals while blocked; let the running threads have the signals.
// (This allows a debugger to break into the running thread.)
sigset_t oldsigs;
sigset_t* allowdebug_blocked = os::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()
assert(_cur_index == -1, "invariant");
if (time == 0) {
_cur_index = REL_INDEX; // arbitrary choice when not timed
status = pthread_cond_wait (&_cond[_cur_index], _mutex) ;
} else {
_cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ;
if (status != 0 && WorkAroundNPTLTimedWaitHang) {
pthread_cond_destroy (&_cond[_cur_index]) ;
pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
}
}
_cur_index = -1;
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") ;
// Paranoia to ensure our locked and lock-free paths interact
// correctly with each other and Java-level accesses.
OrderAccess::fence();
// If externally suspended while waiting, re-suspend
if (jt->handle_special_suspend_equivalent_condition()) {
jt->java_suspend_self();
}
}
void Parker::unpark() {
int s, status ;
status = pthread_mutex_lock(_mutex);
assert (status == 0, "invariant") ;
s = _counter;
_counter = 1;
if (s < 1) {
// thread might be parked
if (_cur_index != -1) {
// thread is definitely parked
if (WorkAroundNPTLTimedWaitHang) {
status = pthread_cond_signal (&_cond[_cur_index]);
assert (status == 0, "invariant");
status = pthread_mutex_unlock(_mutex);
assert (status == 0, "invariant");
} else {
// must capture correct index before unlocking
int index = _cur_index;
status = pthread_mutex_unlock(_mutex);
assert (status == 0, "invariant");
status = pthread_cond_signal (&_cond[index]);
assert (status == 0, "invariant");
}
} else {
pthread_mutex_unlock(_mutex);
assert (status == 0, "invariant") ;
}
} else {
pthread_mutex_unlock(_mutex);
assert (status == 0, "invariant") ;
}
}
extern char** environ;
// 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};
pid_t pid = fork();
if (pid < 0) {
// fork failed
return -1;
} else if (pid == 0) {
// child process
execve("/bin/sh", (char* const*)argv, environ);
// execve failed
_exit(-1);
} else {
// copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
// care about the actual exit code, for now.
int status;
// Wait for the child process to exit. This returns immediately if
// the child has already exited. */
while (waitpid(pid, &status, 0) < 0) {
switch (errno) {
case ECHILD: return 0;
case EINTR: break;
default: return -1;
}
}
if (WIFEXITED(status)) {
// The child exited normally; get its exit code.
return WEXITSTATUS(status);
} else if (WIFSIGNALED(status)) {
// The child exited because of a signal
// The best value to return is 0x80 + signal number,
// because that is what all Unix shells do, and because
// it allows callers to distinguish between process exit and
// process death by signal.
return 0x80 + WTERMSIG(status);
} else {
// Unknown exit code; pass it through
return status;
}
}
}
// is_headless_jre()
//
// Test for the existence of xawt/libmawt.so or libawt_xawt.so
// in order to report if we are running in a headless jre
//
// Since JDK8 xawt/libmawt.so was moved into the same directory
// as libawt.so, and renamed libawt_xawt.so
//
bool os::is_headless_jre() {
struct stat statbuf;
char buf[MAXPATHLEN];
char libmawtpath[MAXPATHLEN];
const char *xawtstr = "/xawt/libmawt.so";
const char *new_xawtstr = "/libawt_xawt.so";
char *p;
// Get path to libjvm.so
os::jvm_path(buf, sizeof(buf));
// Get rid of libjvm.so
p = strrchr(buf, '/');
if (p == NULL) return false;
else *p = '\0';
// Get rid of client or server
p = strrchr(buf, '/');
if (p == NULL) return false;
else *p = '\0';
// check xawt/libmawt.so
strcpy(libmawtpath, buf);
strcat(libmawtpath, xawtstr);
if (::stat(libmawtpath, &statbuf) == 0) return false;
// check libawt_xawt.so
strcpy(libmawtpath, buf);
strcat(libmawtpath, new_xawtstr);
if (::stat(libmawtpath, &statbuf) == 0) return false;
return true;
}
// Get the default path to the core file
// Returns the length of the string
int os::get_core_path(char* buffer, size_t bufferSize) {
const char* p = get_current_directory(buffer, bufferSize);
if (p == NULL) {
assert(p != NULL, "failed to get current directory");
return 0;
}
return strlen(buffer);
}
/////////////// Unit tests ///////////////
#ifndef PRODUCT
#define test_log(...) \
do {\
if (VerboseInternalVMTests) { \
tty->print_cr(__VA_ARGS__); \
tty->flush(); \
}\
} while (false)
class TestReserveMemorySpecial : AllStatic {
public:
static void small_page_write(void* addr, size_t size) {
size_t page_size = os::vm_page_size();
char* end = (char*)addr + size;
for (char* p = (char*)addr; p < end; p += page_size) {
*p = 1;
}
}
static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
if (!UseHugeTLBFS) {
return;
}
test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
if (addr != NULL) {
small_page_write(addr, size);
os::Linux::release_memory_special_huge_tlbfs(addr, size);
}
}
static void test_reserve_memory_special_huge_tlbfs_only() {
if (!UseHugeTLBFS) {
return;
}
size_t lp = os::large_page_size();
for (size_t size = lp; size <= lp * 10; size += lp) {
test_reserve_memory_special_huge_tlbfs_only(size);
}
}
static void test_reserve_memory_special_huge_tlbfs_mixed() {
size_t lp = os::large_page_size();
size_t ag = os::vm_allocation_granularity();
// sizes to test
const size_t sizes[] = {
lp, lp + ag, lp + lp / 2, lp * 2,
lp * 2 + ag, lp * 2 - ag, lp * 2 + lp / 2,
lp * 10, lp * 10 + lp / 2
};
const int num_sizes = sizeof(sizes) / sizeof(size_t);
// For each size/alignment combination, we test three scenarios:
// 1) with req_addr == NULL
// 2) with a non-null req_addr at which we expect to successfully allocate
// 3) with a non-null req_addr which contains a pre-existing mapping, at which we
// expect the allocation to either fail or to ignore req_addr
// Pre-allocate two areas; they shall be as large as the largest allocation
// and aligned to the largest alignment we will be testing.
const size_t mapping_size = sizes[num_sizes - 1] * 2;
char* const mapping1 = (char*) ::mmap(NULL, mapping_size,
PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
-1, 0);
assert(mapping1 != MAP_FAILED, "should work");
char* const mapping2 = (char*) ::mmap(NULL, mapping_size,
PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
-1, 0);
assert(mapping2 != MAP_FAILED, "should work");
// Unmap the first mapping, but leave the second mapping intact: the first
// mapping will serve as a value for a "good" req_addr (case 2). The second
// mapping, still intact, as "bad" req_addr (case 3).
::munmap(mapping1, mapping_size);
// Case 1
test_log("%s, req_addr NULL:", __FUNCTION__);
test_log("size align result");
for (int i = 0; i < num_sizes; i++) {
const size_t size = sizes[i];
for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " -> " PTR_FORMAT " %s",
size, alignment, p, (p != NULL ? "" : "(failed)"));
if (p != NULL) {
assert(is_ptr_aligned(p, alignment), "must be");
small_page_write(p, size);
os::Linux::release_memory_special_huge_tlbfs(p, size);
}
}
}
// Case 2
test_log("%s, req_addr non-NULL:", __FUNCTION__);
test_log("size align req_addr result");
for (int i = 0; i < num_sizes; i++) {
const size_t size = sizes[i];
for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
char* const req_addr = (char*) align_ptr_up(mapping1, alignment);
char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false);
test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s",
size, alignment, req_addr, p,
((p != NULL ? (p == req_addr ? "(exact match)" : "") : "(failed)")));
if (p != NULL) {
assert(p == req_addr, "must be");
small_page_write(p, size);
os::Linux::release_memory_special_huge_tlbfs(p, size);
}
}
}
// Case 3
test_log("%s, req_addr non-NULL with preexisting mapping:", __FUNCTION__);
test_log("size align req_addr result");
for (int i = 0; i < num_sizes; i++) {
const size_t size = sizes[i];
for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
char* const req_addr = (char*) align_ptr_up(mapping2, alignment);
char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false);
test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s",
size, alignment, req_addr, p,
((p != NULL ? "" : "(failed)")));
// as the area around req_addr contains already existing mappings, the API should always
// return NULL (as per contract, it cannot return another address)
assert(p == NULL, "must be");
}
}
::munmap(mapping2, mapping_size);
}
static void test_reserve_memory_special_huge_tlbfs() {
if (!UseHugeTLBFS) {
return;
}
test_reserve_memory_special_huge_tlbfs_only();
test_reserve_memory_special_huge_tlbfs_mixed();
}
static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
if (!UseSHM) {
return;
}
test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
if (addr != NULL) {
assert(is_ptr_aligned(addr, alignment), "Check");
assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
small_page_write(addr, size);
os::Linux::release_memory_special_shm(addr, size);
}
}
static void test_reserve_memory_special_shm() {
size_t lp = os::large_page_size();
size_t ag = os::vm_allocation_granularity();
for (size_t size = ag; size < lp * 3; size += ag) {
for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
test_reserve_memory_special_shm(size, alignment);
}
}
}
static void test() {
test_reserve_memory_special_huge_tlbfs();
test_reserve_memory_special_shm();
}
};
void TestReserveMemorySpecial_test() {
TestReserveMemorySpecial::test();
}
#endif