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android / platform / libcore / 8153779ad32 / . / hotspot / src / share / vm / runtime / os.cpp
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/*
* Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
# include "incls/_precompiled.incl"
# include "incls/_os.cpp.incl"
# include <signal.h>
OSThread* os::_starting_thread = NULL;
address os::_polling_page = NULL;
volatile int32_t* os::_mem_serialize_page = NULL;
uintptr_t os::_serialize_page_mask = 0;
long os::_rand_seed = 1;
int os::_processor_count = 0;
volatile jlong os::_global_time = 0;
volatile int os::_global_time_lock = 0;
bool os::_use_global_time = false;
size_t os::_page_sizes[os::page_sizes_max];
#ifndef PRODUCT
int os::num_mallocs = 0; // # of calls to malloc/realloc
size_t os::alloc_bytes = 0; // # of bytes allocated
int os::num_frees = 0; // # of calls to free
#endif
// Atomic read of a jlong is assured by a seqlock; see update_global_time()
jlong os::read_global_time() {
#ifdef _LP64
return _global_time;
#else
volatile int lock;
volatile jlong current_time;
int ctr = 0;
for (;;) {
lock = _global_time_lock;
// spin while locked
while ((lock & 0x1) != 0) {
++ctr;
if ((ctr & 0xFFF) == 0) {
// Guarantee writer progress. Can't use yield; yield is advisory
// and has almost no effect on some platforms. Don't need a state
// transition - the park call will return promptly.
assert(Thread::current() != NULL, "TLS not initialized");
assert(Thread::current()->_ParkEvent != NULL, "sync not initialized");
Thread::current()->_ParkEvent->park(1);
}
lock = _global_time_lock;
}
OrderAccess::loadload();
current_time = _global_time;
OrderAccess::loadload();
// ratify seqlock value
if (lock == _global_time_lock) {
return current_time;
}
}
#endif
}
//
// NOTE - Assumes only one writer thread!
//
// We use a seqlock to guarantee that jlong _global_time is updated
// atomically on 32-bit platforms. A locked value is indicated by
// the lock variable LSB == 1. Readers will initially read the lock
// value, spinning until the LSB == 0. They then speculatively read
// the global time value, then re-read the lock value to ensure that
// it hasn't changed. If the lock value has changed, the entire read
// sequence is retried.
//
// Writers simply set the LSB = 1 (i.e. increment the variable),
// update the global time, then release the lock and bump the version
// number (i.e. increment the variable again.) In this case we don't
// even need a CAS since we ensure there's only one writer.
//
void os::update_global_time() {
#ifdef _LP64
_global_time = timeofday();
#else
assert((_global_time_lock & 0x1) == 0, "multiple writers?");
jlong current_time = timeofday();
_global_time_lock++; // lock
OrderAccess::storestore();
_global_time = current_time;
OrderAccess::storestore();
_global_time_lock++; // unlock
#endif
}
// Fill in buffer with current local time as an ISO-8601 string.
// E.g., yyyy-mm-ddThh:mm:ss-zzzz.
// Returns buffer, or NULL if it failed.
// This would mostly be a call to
// strftime(...., "%Y-%m-%d" "T" "%H:%M:%S" "%z", ....)
// except that on Windows the %z behaves badly, so we do it ourselves.
// Also, people wanted milliseconds on there,
// and strftime doesn't do milliseconds.
char* os::iso8601_time(char* buffer, size_t buffer_length) {
// Output will be of the form "YYYY-MM-DDThh:mm:ss.mmm+zzzz\0"
// 1 2
// 12345678901234567890123456789
static const char* iso8601_format =
"%04d-%02d-%02dT%02d:%02d:%02d.%03d%c%02d%02d";
static const size_t needed_buffer = 29;
// Sanity check the arguments
if (buffer == NULL) {
assert(false, "NULL buffer");
return NULL;
}
if (buffer_length < needed_buffer) {
assert(false, "buffer_length too small");
return NULL;
}
// Get the current time
jlong milliseconds_since_19700101 = timeofday();
const int milliseconds_per_microsecond = 1000;
const time_t seconds_since_19700101 =
milliseconds_since_19700101 / milliseconds_per_microsecond;
const int milliseconds_after_second =
milliseconds_since_19700101 % milliseconds_per_microsecond;
// Convert the time value to a tm and timezone variable
const struct tm *time_struct_temp = localtime(&seconds_since_19700101);
if (time_struct_temp == NULL) {
assert(false, "Failed localtime");
return NULL;
}
// Save the results of localtime
const struct tm time_struct = *time_struct_temp;
const time_t zone = timezone;
// If daylight savings time is in effect,
// we are 1 hour East of our time zone
const time_t seconds_per_minute = 60;
const time_t minutes_per_hour = 60;
const time_t seconds_per_hour = seconds_per_minute * minutes_per_hour;
time_t UTC_to_local = zone;
if (time_struct.tm_isdst > 0) {
UTC_to_local = UTC_to_local - seconds_per_hour;
}
// Compute the time zone offset.
// localtime(3C) sets timezone to the difference (in seconds)
// between UTC and and local time.
// ISO 8601 says we need the difference between local time and UTC,
// we change the sign of the localtime(3C) result.
const time_t local_to_UTC = -(UTC_to_local);
// Then we have to figure out if if we are ahead (+) or behind (-) UTC.
char sign_local_to_UTC = '+';
time_t abs_local_to_UTC = local_to_UTC;
if (local_to_UTC < 0) {
sign_local_to_UTC = '-';
abs_local_to_UTC = -(abs_local_to_UTC);
}
// Convert time zone offset seconds to hours and minutes.
const time_t zone_hours = (abs_local_to_UTC / seconds_per_hour);
const time_t zone_min =
((abs_local_to_UTC % seconds_per_hour) / seconds_per_minute);
// Print an ISO 8601 date and time stamp into the buffer
const int year = 1900 + time_struct.tm_year;
const int month = 1 + time_struct.tm_mon;
const int printed = jio_snprintf(buffer, buffer_length, iso8601_format,
year,
month,
time_struct.tm_mday,
time_struct.tm_hour,
time_struct.tm_min,
time_struct.tm_sec,
milliseconds_after_second,
sign_local_to_UTC,
zone_hours,
zone_min);
if (printed == 0) {
assert(false, "Failed jio_printf");
return NULL;
}
return buffer;
}
OSReturn os::set_priority(Thread* thread, ThreadPriority p) {
#ifdef ASSERT
if (!(!thread->is_Java_thread() ||
Thread::current() == thread ||
Threads_lock->owned_by_self()
|| thread->is_Compiler_thread()
)) {
assert(false, "possibility of dangling Thread pointer");
}
#endif
if (p >= MinPriority && p <= MaxPriority) {
int priority = java_to_os_priority[p];
return set_native_priority(thread, priority);
} else {
assert(false, "Should not happen");
return OS_ERR;
}
}
OSReturn os::get_priority(const Thread* const thread, ThreadPriority& priority) {
int p;
int os_prio;
OSReturn ret = get_native_priority(thread, &os_prio);
if (ret != OS_OK) return ret;
for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] > os_prio; p--) ;
priority = (ThreadPriority)p;
return OS_OK;
}
// --------------------- sun.misc.Signal (optional) ---------------------
// SIGBREAK is sent by the keyboard to query the VM state
#ifndef SIGBREAK
#define SIGBREAK SIGQUIT
#endif
// sigexitnum_pd is a platform-specific special signal used for terminating the Signal thread.
static void signal_thread_entry(JavaThread* thread, TRAPS) {
os::set_priority(thread, NearMaxPriority);
while (true) {
int sig;
{
// FIXME : Currently we have not decieded what should be the status
// for this java thread blocked here. Once we decide about
// that we should fix this.
sig = os::signal_wait();
}
if (sig == os::sigexitnum_pd()) {
// Terminate the signal thread
return;
}
switch (sig) {
case SIGBREAK: {
// Check if the signal is a trigger to start the Attach Listener - in that
// case don't print stack traces.
if (!DisableAttachMechanism && AttachListener::is_init_trigger()) {
continue;
}
// Print stack traces
// Any SIGBREAK operations added here should make sure to flush
// the output stream (e.g. tty->flush()) after output. See 4803766.
// Each module also prints an extra carriage return after its output.
VM_PrintThreads op;
VMThread::execute(&op);
VM_PrintJNI jni_op;
VMThread::execute(&jni_op);
VM_FindDeadlocks op1(tty);
VMThread::execute(&op1);
Universe::print_heap_at_SIGBREAK();
if (PrintClassHistogram) {
VM_GC_HeapInspection op1(gclog_or_tty, true /* force full GC before heap inspection */);
VMThread::execute(&op1);
}
if (JvmtiExport::should_post_data_dump()) {
JvmtiExport::post_data_dump();
}
break;
}
default: {
// Dispatch the signal to java
HandleMark hm(THREAD);
klassOop k = SystemDictionary::resolve_or_null(vmSymbolHandles::sun_misc_Signal(), THREAD);
KlassHandle klass (THREAD, k);
if (klass.not_null()) {
JavaValue result(T_VOID);
JavaCallArguments args;
args.push_int(sig);
JavaCalls::call_static(
&result,
klass,
vmSymbolHandles::dispatch_name(),
vmSymbolHandles::int_void_signature(),
&args,
THREAD
);
}
if (HAS_PENDING_EXCEPTION) {
// tty is initialized early so we don't expect it to be null, but
// if it is we can't risk doing an initialization that might
// trigger additional out-of-memory conditions
if (tty != NULL) {
char klass_name[256];
char tmp_sig_name[16];
const char* sig_name = "UNKNOWN";
instanceKlass::cast(PENDING_EXCEPTION->klass())->
name()->as_klass_external_name(klass_name, 256);
if (os::exception_name(sig, tmp_sig_name, 16) != NULL)
sig_name = tmp_sig_name;
warning("Exception %s occurred dispatching signal %s to handler"
"- the VM may need to be forcibly terminated",
klass_name, sig_name );
}
CLEAR_PENDING_EXCEPTION;
}
}
}
}
}
void os::signal_init() {
if (!ReduceSignalUsage) {
// Setup JavaThread for processing signals
EXCEPTION_MARK;
klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK);
instanceKlassHandle klass (THREAD, k);
instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
const char thread_name[] = "Signal Dispatcher";
Handle string = java_lang_String::create_from_str(thread_name, CHECK);
// Initialize thread_oop to put it into the system threadGroup
Handle thread_group (THREAD, Universe::system_thread_group());
JavaValue result(T_VOID);
JavaCalls::call_special(&result, thread_oop,
klass,
vmSymbolHandles::object_initializer_name(),
vmSymbolHandles::threadgroup_string_void_signature(),
thread_group,
string,
CHECK);
KlassHandle group(THREAD, SystemDictionary::threadGroup_klass());
JavaCalls::call_special(&result,
thread_group,
group,
vmSymbolHandles::add_method_name(),
vmSymbolHandles::thread_void_signature(),
thread_oop, // ARG 1
CHECK);
os::signal_init_pd();
{ MutexLocker mu(Threads_lock);
JavaThread* signal_thread = new JavaThread(&signal_thread_entry);
// At this point it may be possible that no osthread was created for the
// JavaThread due to lack of memory. We would have to throw an exception
// in that case. However, since this must work and we do not allow
// exceptions anyway, check and abort if this fails.
if (signal_thread == NULL || signal_thread->osthread() == NULL) {
vm_exit_during_initialization("java.lang.OutOfMemoryError",
"unable to create new native thread");
}
java_lang_Thread::set_thread(thread_oop(), signal_thread);
java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
java_lang_Thread::set_daemon(thread_oop());
signal_thread->set_threadObj(thread_oop());
Threads::add(signal_thread);
Thread::start(signal_thread);
}
// Handle ^BREAK
os::signal(SIGBREAK, os::user_handler());
}
}
void os::terminate_signal_thread() {
if (!ReduceSignalUsage)
signal_notify(sigexitnum_pd());
}
// --------------------- loading libraries ---------------------
typedef jint (JNICALL *JNI_OnLoad_t)(JavaVM *, void *);
extern struct JavaVM_ main_vm;
static void* _native_java_library = NULL;
void* os::native_java_library() {
if (_native_java_library == NULL) {
char buffer[JVM_MAXPATHLEN];
char ebuf[1024];
// Try to load verify dll first. In 1.3 java dll depends on it and is not always
// able to find it when the loading executable is outside the JDK.
// In order to keep working with 1.2 we ignore any loading errors.
hpi::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), "verify");
hpi::dll_load(buffer, ebuf, sizeof(ebuf));
// Load java dll
hpi::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), "java");
_native_java_library = hpi::dll_load(buffer, ebuf, sizeof(ebuf));
if (_native_java_library == NULL) {
vm_exit_during_initialization("Unable to load native library", ebuf);
}
// The JNI_OnLoad handling is normally done by method load in java.lang.ClassLoader$NativeLibrary,
// but the VM loads the base library explicitly so we have to check for JNI_OnLoad as well
const char *onLoadSymbols[] = JNI_ONLOAD_SYMBOLS;
JNI_OnLoad_t JNI_OnLoad = CAST_TO_FN_PTR(JNI_OnLoad_t, hpi::dll_lookup(_native_java_library, onLoadSymbols[0]));
if (JNI_OnLoad != NULL) {
JavaThread* thread = JavaThread::current();
ThreadToNativeFromVM ttn(thread);
HandleMark hm(thread);
jint ver = (*JNI_OnLoad)(&main_vm, NULL);
if (!Threads::is_supported_jni_version_including_1_1(ver)) {
vm_exit_during_initialization("Unsupported JNI version");
}
}
}
return _native_java_library;
}
// --------------------- heap allocation utilities ---------------------
char *os::strdup(const char *str) {
size_t size = strlen(str);
char *dup_str = (char *)malloc(size + 1);
if (dup_str == NULL) return NULL;
strcpy(dup_str, str);
return dup_str;
}
#ifdef ASSERT
#define space_before (MallocCushion + sizeof(double))
#define space_after MallocCushion
#define size_addr_from_base(p) (size_t*)(p + space_before - sizeof(size_t))
#define size_addr_from_obj(p) ((size_t*)p - 1)
// MallocCushion: size of extra cushion allocated around objects with +UseMallocOnly
// NB: cannot be debug variable, because these aren't set from the command line until
// *after* the first few allocs already happened
#define MallocCushion 16
#else
#define space_before 0
#define space_after 0
#define size_addr_from_base(p) should not use w/o ASSERT
#define size_addr_from_obj(p) should not use w/o ASSERT
#define MallocCushion 0
#endif
#define paranoid 0 /* only set to 1 if you suspect checking code has bug */
#ifdef ASSERT
inline size_t get_size(void* obj) {
size_t size = *size_addr_from_obj(obj);
if (size < 0 )
fatal2("free: size field of object #%p was overwritten (%lu)", obj, size);
return size;
}
u_char* find_cushion_backwards(u_char* start) {
u_char* p = start;
while (p[ 0] != badResourceValue || p[-1] != badResourceValue ||
p[-2] != badResourceValue || p[-3] != badResourceValue) p--;
// ok, we have four consecutive marker bytes; find start
u_char* q = p - 4;
while (*q == badResourceValue) q--;
return q + 1;
}
u_char* find_cushion_forwards(u_char* start) {
u_char* p = start;
while (p[0] != badResourceValue || p[1] != badResourceValue ||
p[2] != badResourceValue || p[3] != badResourceValue) p++;
// ok, we have four consecutive marker bytes; find end of cushion
u_char* q = p + 4;
while (*q == badResourceValue) q++;
return q - MallocCushion;
}
void print_neighbor_blocks(void* ptr) {
// find block allocated before ptr (not entirely crash-proof)
if (MallocCushion < 4) {
tty->print_cr("### cannot find previous block (MallocCushion < 4)");
return;
}
u_char* start_of_this_block = (u_char*)ptr - space_before;
u_char* end_of_prev_block_data = start_of_this_block - space_after -1;
// look for cushion in front of prev. block
u_char* start_of_prev_block = find_cushion_backwards(end_of_prev_block_data);
ptrdiff_t size = *size_addr_from_base(start_of_prev_block);
u_char* obj = start_of_prev_block + space_before;
if (size <= 0 ) {
// start is bad; mayhave been confused by OS data inbetween objects
// search one more backwards
start_of_prev_block = find_cushion_backwards(start_of_prev_block);
size = *size_addr_from_base(start_of_prev_block);
obj = start_of_prev_block + space_before;
}
if (start_of_prev_block + space_before + size + space_after == start_of_this_block) {
tty->print_cr("### previous object: %p (%ld bytes)", obj, size);
} else {
tty->print_cr("### previous object (not sure if correct): %p (%ld bytes)", obj, size);
}
// now find successor block
u_char* start_of_next_block = (u_char*)ptr + *size_addr_from_obj(ptr) + space_after;
start_of_next_block = find_cushion_forwards(start_of_next_block);
u_char* next_obj = start_of_next_block + space_before;
ptrdiff_t next_size = *size_addr_from_base(start_of_next_block);
if (start_of_next_block[0] == badResourceValue &&
start_of_next_block[1] == badResourceValue &&
start_of_next_block[2] == badResourceValue &&
start_of_next_block[3] == badResourceValue) {
tty->print_cr("### next object: %p (%ld bytes)", next_obj, next_size);
} else {
tty->print_cr("### next object (not sure if correct): %p (%ld bytes)", next_obj, next_size);
}
}
void report_heap_error(void* memblock, void* bad, const char* where) {
tty->print_cr("## nof_mallocs = %d, nof_frees = %d", os::num_mallocs, os::num_frees);
tty->print_cr("## memory stomp: byte at %p %s object %p", bad, where, memblock);
print_neighbor_blocks(memblock);
fatal("memory stomping error");
}
void verify_block(void* memblock) {
size_t size = get_size(memblock);
if (MallocCushion) {
u_char* ptr = (u_char*)memblock - space_before;
for (int i = 0; i < MallocCushion; i++) {
if (ptr[i] != badResourceValue) {
report_heap_error(memblock, ptr+i, "in front of");
}
}
u_char* end = (u_char*)memblock + size + space_after;
for (int j = -MallocCushion; j < 0; j++) {
if (end[j] != badResourceValue) {
report_heap_error(memblock, end+j, "after");
}
}
}
}
#endif
void* os::malloc(size_t size) {
NOT_PRODUCT(num_mallocs++);
NOT_PRODUCT(alloc_bytes += size);
if (size == 0) {
// return a valid pointer if size is zero
// if NULL is returned the calling functions assume out of memory.
size = 1;
}
NOT_PRODUCT(if (MallocVerifyInterval > 0) check_heap());
u_char* ptr = (u_char*)::malloc(size + space_before + space_after);
#ifdef ASSERT
if (ptr == NULL) return NULL;
if (MallocCushion) {
for (u_char* p = ptr; p < ptr + MallocCushion; p++) *p = (u_char)badResourceValue;
u_char* end = ptr + space_before + size;
for (u_char* pq = ptr+MallocCushion; pq < end; pq++) *pq = (u_char)uninitBlockPad;
for (u_char* q = end; q < end + MallocCushion; q++) *q = (u_char)badResourceValue;
}
// put size just before data
*size_addr_from_base(ptr) = size;
#endif
u_char* memblock = ptr + space_before;
if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
tty->print_cr("os::malloc caught, %lu bytes --> %p", size, memblock);
breakpoint();
}
debug_only(if (paranoid) verify_block(memblock));
if (PrintMalloc && tty != NULL) tty->print_cr("os::malloc %lu bytes --> %p", size, memblock);
return memblock;
}
void* os::realloc(void *memblock, size_t size) {
NOT_PRODUCT(num_mallocs++);
NOT_PRODUCT(alloc_bytes += size);
#ifndef ASSERT
return ::realloc(memblock, size);
#else
if (memblock == NULL) {
return os::malloc(size);
}
if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
tty->print_cr("os::realloc caught %p", memblock);
breakpoint();
}
verify_block(memblock);
NOT_PRODUCT(if (MallocVerifyInterval > 0) check_heap());
if (size == 0) return NULL;
// always move the block
void* ptr = malloc(size);
if (PrintMalloc) tty->print_cr("os::remalloc %lu bytes, %p --> %p", size, memblock, ptr);
// Copy to new memory if malloc didn't fail
if ( ptr != NULL ) {
memcpy(ptr, memblock, MIN2(size, get_size(memblock)));
if (paranoid) verify_block(ptr);
if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
tty->print_cr("os::realloc caught, %lu bytes --> %p", size, ptr);
breakpoint();
}
free(memblock);
}
return ptr;
#endif
}
void os::free(void *memblock) {
NOT_PRODUCT(num_frees++);
#ifdef ASSERT
if (memblock == NULL) return;
if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
if (tty != NULL) tty->print_cr("os::free caught %p", memblock);
breakpoint();
}
verify_block(memblock);
if (PrintMalloc && tty != NULL)
// tty->print_cr("os::free %p", memblock);
fprintf(stderr, "os::free %p\n", memblock);
NOT_PRODUCT(if (MallocVerifyInterval > 0) check_heap());
// Added by detlefs.
if (MallocCushion) {
u_char* ptr = (u_char*)memblock - space_before;
for (u_char* p = ptr; p < ptr + MallocCushion; p++) {
guarantee(*p == badResourceValue,
"Thing freed should be malloc result.");
*p = (u_char)freeBlockPad;
}
size_t size = get_size(memblock);
u_char* end = ptr + space_before + size;
for (u_char* q = end; q < end + MallocCushion; q++) {
guarantee(*q == badResourceValue,
"Thing freed should be malloc result.");
*q = (u_char)freeBlockPad;
}
}
#endif
::free((char*)memblock - space_before);
}
void os::init_random(long initval) {
_rand_seed = initval;
}
long os::random() {
/* standard, well-known linear congruential random generator with
* next_rand = (16807*seed) mod (2**31-1)
* see
* (1) "Random Number Generators: Good Ones Are Hard to Find",
* S.K. Park and K.W. Miller, Communications of the ACM 31:10 (Oct 1988),
* (2) "Two Fast Implementations of the 'Minimal Standard' Random
* Number Generator", David G. Carta, Comm. ACM 33, 1 (Jan 1990), pp. 87-88.
*/
const long a = 16807;
const unsigned long m = 2147483647;
const long q = m / a; assert(q == 127773, "weird math");
const long r = m % a; assert(r == 2836, "weird math");
// compute az=2^31p+q
unsigned long lo = a * (long)(_rand_seed & 0xFFFF);
unsigned long hi = a * (long)((unsigned long)_rand_seed >> 16);
lo += (hi & 0x7FFF) << 16;
// if q overflowed, ignore the overflow and increment q
if (lo > m) {
lo &= m;
++lo;
}
lo += hi >> 15;
// if (p+q) overflowed, ignore the overflow and increment (p+q)
if (lo > m) {
lo &= m;
++lo;
}
return (_rand_seed = lo);
}
// The INITIALIZED state is distinguished from the SUSPENDED state because the
// conditions in which a thread is first started are different from those in which
// a suspension is resumed. These differences make it hard for us to apply the
// tougher checks when starting threads that we want to do when resuming them.
// However, when start_thread is called as a result of Thread.start, on a Java
// thread, the operation is synchronized on the Java Thread object. So there
// cannot be a race to start the thread and hence for the thread to exit while
// we are working on it. Non-Java threads that start Java threads either have
// to do so in a context in which races are impossible, or should do appropriate
// locking.
void os::start_thread(Thread* thread) {
// guard suspend/resume
MutexLockerEx ml(thread->SR_lock(), Mutex::_no_safepoint_check_flag);
OSThread* osthread = thread->osthread();
osthread->set_state(RUNNABLE);
pd_start_thread(thread);
}
//---------------------------------------------------------------------------
// Helper functions for fatal error handler
void os::print_hex_dump(outputStream* st, address start, address end, int unitsize) {
assert(unitsize == 1 || unitsize == 2 || unitsize == 4 || unitsize == 8, "just checking");
int cols = 0;
int cols_per_line = 0;
switch (unitsize) {
case 1: cols_per_line = 16; break;
case 2: cols_per_line = 8; break;
case 4: cols_per_line = 4; break;
case 8: cols_per_line = 2; break;
default: return;
}
address p = start;
st->print(PTR_FORMAT ": ", start);
while (p < end) {
switch (unitsize) {
case 1: st->print("%02x", *(u1*)p); break;
case 2: st->print("%04x", *(u2*)p); break;
case 4: st->print("%08x", *(u4*)p); break;
case 8: st->print("%016" FORMAT64_MODIFIER "x", *(u8*)p); break;
}
p += unitsize;
cols++;
if (cols >= cols_per_line && p < end) {
cols = 0;
st->cr();
st->print(PTR_FORMAT ": ", p);
} else {
st->print(" ");
}
}
st->cr();
}
void os::print_environment_variables(outputStream* st, const char** env_list,
char* buffer, int len) {
if (env_list) {
st->print_cr("Environment Variables:");
for (int i = 0; env_list[i] != NULL; i++) {
if (getenv(env_list[i], buffer, len)) {
st->print(env_list[i]);
st->print("=");
st->print_cr(buffer);
}
}
}
}
void os::print_cpu_info(outputStream* st) {
// cpu
st->print("CPU:");
st->print("total %d", os::processor_count());
// It's not safe to query number of active processors after crash
// st->print("(active %d)", os::active_processor_count());
st->print(" %s", VM_Version::cpu_features());
st->cr();
}
void os::print_date_and_time(outputStream *st) {
time_t tloc;
(void)time(&tloc);
st->print("time: %s", ctime(&tloc)); // ctime adds newline.
double t = os::elapsedTime();
// NOTE: It tends to crash after a SEGV if we want to printf("%f",...) in
// Linux. Must be a bug in glibc ? Workaround is to round "t" to int
// before printf. We lost some precision, but who cares?
st->print_cr("elapsed time: %d seconds", (int)t);
}
// Looks like all platforms except IA64 can use the same function to check
// if C stack is walkable beyond current frame. The check for fp() is not
// necessary on Sparc, but it's harmless.
bool os::is_first_C_frame(frame* fr) {
#ifdef IA64
// In order to walk native frames on Itanium, we need to access the unwind
// table, which is inside ELF. We don't want to parse ELF after fatal error,
// so return true for IA64. If we need to support C stack walking on IA64,
// this function needs to be moved to CPU specific files, as fp() on IA64
// is register stack, which grows towards higher memory address.
return true;
#endif
// Load up sp, fp, sender sp and sender fp, check for reasonable values.
// Check usp first, because if that's bad the other accessors may fault
// on some architectures. Ditto ufp second, etc.
uintptr_t fp_align_mask = (uintptr_t)(sizeof(address)-1);
// sp on amd can be 32 bit aligned.
uintptr_t sp_align_mask = (uintptr_t)(sizeof(int)-1);
uintptr_t usp = (uintptr_t)fr->sp();
if ((usp & sp_align_mask) != 0) return true;
uintptr_t ufp = (uintptr_t)fr->fp();
if ((ufp & fp_align_mask) != 0) return true;
uintptr_t old_sp = (uintptr_t)fr->sender_sp();
if ((old_sp & sp_align_mask) != 0) return true;
if (old_sp == 0 || old_sp == (uintptr_t)-1) return true;
uintptr_t old_fp = (uintptr_t)fr->link();
if ((old_fp & fp_align_mask) != 0) return true;
if (old_fp == 0 || old_fp == (uintptr_t)-1 || old_fp == ufp) return true;
// stack grows downwards; if old_fp is below current fp or if the stack
// frame is too large, either the stack is corrupted or fp is not saved
// on stack (i.e. on x86, ebp may be used as general register). The stack
// is not walkable beyond current frame.
if (old_fp < ufp) return true;
if (old_fp - ufp > 64 * K) return true;
return false;
}
#ifdef ASSERT
extern "C" void test_random() {
const double m = 2147483647;
double mean = 0.0, variance = 0.0, t;
long reps = 10000;
unsigned long seed = 1;
tty->print_cr("seed %ld for %ld repeats...", seed, reps);
os::init_random(seed);
long num;
for (int k = 0; k < reps; k++) {
num = os::random();
double u = (double)num / m;
assert(u >= 0.0 && u <= 1.0, "bad random number!");
// calculate mean and variance of the random sequence
mean += u;
variance += (u*u);
}
mean /= reps;
variance /= (reps - 1);
assert(num == 1043618065, "bad seed");
tty->print_cr("mean of the 1st 10000 numbers: %f", mean);
tty->print_cr("variance of the 1st 10000 numbers: %f", variance);
const double eps = 0.0001;
t = fabsd(mean - 0.5018);
assert(t < eps, "bad mean");
t = (variance - 0.3355) < 0.0 ? -(variance - 0.3355) : variance - 0.3355;
assert(t < eps, "bad variance");
}
#endif
// Set up the boot classpath.
char* os::format_boot_path(const char* format_string,
const char* home,
int home_len,
char fileSep,
char pathSep) {
assert((fileSep == '/' && pathSep == ':') ||
(fileSep == '\\' && pathSep == ';'), "unexpected seperator chars");
// Scan the format string to determine the length of the actual
// boot classpath, and handle platform dependencies as well.
int formatted_path_len = 0;
const char* p;
for (p = format_string; *p != 0; ++p) {
if (*p == '%') formatted_path_len += home_len - 1;
++formatted_path_len;
}
char* formatted_path = NEW_C_HEAP_ARRAY(char, formatted_path_len + 1);
if (formatted_path == NULL) {
return NULL;
}
// Create boot classpath from format, substituting separator chars and
// java home directory.
char* q = formatted_path;
for (p = format_string; *p != 0; ++p) {
switch (*p) {
case '%':
strcpy(q, home);
q += home_len;
break;
case '/':
*q++ = fileSep;
break;
case ':':
*q++ = pathSep;
break;
default:
*q++ = *p;
}
}
*q = '\0';
assert((q - formatted_path) == formatted_path_len, "formatted_path size botched");
return formatted_path;
}
bool os::set_boot_path(char fileSep, char pathSep) {
const char* home = Arguments::get_java_home();
int home_len = (int)strlen(home);
static const char* meta_index_dir_format = "%/lib/";
static const char* meta_index_format = "%/lib/meta-index";
char* meta_index = format_boot_path(meta_index_format, home, home_len, fileSep, pathSep);
if (meta_index == NULL) return false;
char* meta_index_dir = format_boot_path(meta_index_dir_format, home, home_len, fileSep, pathSep);
if (meta_index_dir == NULL) return false;
Arguments::set_meta_index_path(meta_index, meta_index_dir);
// Any modification to the JAR-file list, for the boot classpath must be
// aligned with install/install/make/common/Pack.gmk. Note: boot class
// path class JARs, are stripped for StackMapTable to reduce download size.
static const char classpath_format[] =
"%/lib/resources.jar:"
"%/lib/rt.jar:"
"%/lib/sunrsasign.jar:"
"%/lib/jsse.jar:"
"%/lib/jce.jar:"
"%/lib/charsets.jar:"
"%/classes";
char* sysclasspath = format_boot_path(classpath_format, home, home_len, fileSep, pathSep);
if (sysclasspath == NULL) return false;
Arguments::set_sysclasspath(sysclasspath);
return true;
}
void os::set_memory_serialize_page(address page) {
int count = log2_intptr(sizeof(class JavaThread)) - log2_intptr(64);
_mem_serialize_page = (volatile int32_t *)page;
// We initialize the serialization page shift count here
// We assume a cache line size of 64 bytes
assert(SerializePageShiftCount == count,
"thread size changed, fix SerializePageShiftCount constant");
set_serialize_page_mask((uintptr_t)(vm_page_size() - sizeof(int32_t)));
}
// This method is called from signal handler when SIGSEGV occurs while the current
// thread tries to store to the "read-only" memory serialize page during state
// transition.
void os::block_on_serialize_page_trap() {
if (TraceSafepoint) {
tty->print_cr("Block until the serialize page permission restored");
}
// When VMThread is holding the SerializePage_lock during modifying the
// access permission of the memory serialize page, the following call
// will block until the permission of that page is restored to rw.
// Generally, it is unsafe to manipulate locks in signal handlers, but in
// this case, it's OK as the signal is synchronous and we know precisely when
// it can occur. SerializePage_lock is a transiently-held leaf lock, so
// lock_without_safepoint_check should be safe.
SerializePage_lock->lock_without_safepoint_check();
SerializePage_lock->unlock();
}
// Serialize all thread state variables
void os::serialize_thread_states() {
// On some platforms such as Solaris & Linux, the time duration of the page
// permission restoration is observed to be much longer than expected due to
// scheduler starvation problem etc. To avoid the long synchronization
// time and expensive page trap spinning, 'SerializePage_lock' is used to block
// the mutator thread if such case is encountered. Since this method is always
// called by VMThread during safepoint, lock_without_safepoint_check is used
// instead. See bug 6546278.
SerializePage_lock->lock_without_safepoint_check();
os::protect_memory( (char *)os::get_memory_serialize_page(), os::vm_page_size() );
os::unguard_memory( (char *)os::get_memory_serialize_page(), os::vm_page_size() );
SerializePage_lock->unlock();
}
// Returns true if the current stack pointer is above the stack shadow
// pages, false otherwise.
bool os::stack_shadow_pages_available(Thread *thread, methodHandle method) {
assert(StackRedPages > 0 && StackYellowPages > 0,"Sanity check");
address sp = current_stack_pointer();
// Check if we have StackShadowPages above the yellow zone. This parameter
// is dependant on the depth of the maximum VM call stack possible from
// the handler for stack overflow. 'instanceof' in the stack overflow
// handler or a println uses at least 8k stack of VM and native code
// respectively.
const int framesize_in_bytes =
Interpreter::size_top_interpreter_activation(method()) * wordSize;
int reserved_area = ((StackShadowPages + StackRedPages + StackYellowPages)
* vm_page_size()) + framesize_in_bytes;
// The very lower end of the stack
address stack_limit = thread->stack_base() - thread->stack_size();
return (sp > (stack_limit + reserved_area));
}
size_t os::page_size_for_region(size_t region_min_size, size_t region_max_size,
uint min_pages)
{
assert(min_pages > 0, "sanity");
if (UseLargePages) {
const size_t max_page_size = region_max_size / min_pages;
for (unsigned int i = 0; _page_sizes[i] != 0; ++i) {
const size_t sz = _page_sizes[i];
const size_t mask = sz - 1;
if ((region_min_size & mask) == 0 && (region_max_size & mask) == 0) {
// The largest page size with no fragmentation.
return sz;
}
if (sz <= max_page_size) {
// The largest page size that satisfies the min_pages requirement.
return sz;
}
}
}
return vm_page_size();
}
#ifndef PRODUCT
void os::trace_page_sizes(const char* str, const size_t region_min_size,
const size_t region_max_size, const size_t page_size,
const char* base, const size_t size)
{
if (TracePageSizes) {
tty->print_cr("%s: min=" SIZE_FORMAT " max=" SIZE_FORMAT
" pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT
" size=" SIZE_FORMAT,
str, region_min_size, region_max_size,
page_size, base, size);
}
}
#endif // #ifndef PRODUCT
// This is the working definition of a server class machine:
// >= 2 physical CPU's and >=2GB of memory, with some fuzz
// because the graphics memory (?) sometimes masks physical memory.
// If you want to change the definition of a server class machine
// on some OS or platform, e.g., >=4GB on Windohs platforms,
// then you'll have to parameterize this method based on that state,
// as was done for logical processors here, or replicate and
// specialize this method for each platform. (Or fix os to have
// some inheritance structure and use subclassing. Sigh.)
// If you want some platform to always or never behave as a server
// class machine, change the setting of AlwaysActAsServerClassMachine
// and NeverActAsServerClassMachine in globals*.hpp.
bool os::is_server_class_machine() {
// First check for the early returns
if (NeverActAsServerClassMachine) {
return false;
}
if (AlwaysActAsServerClassMachine) {
return true;
}
// Then actually look at the machine
bool result = false;
const unsigned int server_processors = 2;
const julong server_memory = 2UL * G;
// We seem not to get our full complement of memory.
// We allow some part (1/8?) of the memory to be "missing",
// based on the sizes of DIMMs, and maybe graphics cards.
const julong missing_memory = 256UL * M;
/* Is this a server class machine? */
if ((os::active_processor_count() >= (int)server_processors) &&
(os::physical_memory() >= (server_memory - missing_memory))) {
const unsigned int logical_processors =
VM_Version::logical_processors_per_package();
if (logical_processors > 1) {
const unsigned int physical_packages =
os::active_processor_count() / logical_processors;
if (physical_packages > server_processors) {
result = true;
}
} else {
result = true;
}
}
return result;
}