extern "C" JNIEXPORT int
JVM_handle_linux_signal(int sig,
siginfo_t* info,
void* ucVoid,
int abort_if_unrecognized) {
// in fact this isn't ucontext_t* at all, but struct sigcontext*
// but Linux porting layer uses ucontext_t, so to minimize code change
// we cast as needed
ucontext_t* ucFake = (ucontext_t*) ucVoid;
sigcontext* uc = (sigcontext*)ucVoid;
Thread* t = ThreadLocalStorage::get_thread_slow();
SignalHandlerMark shm(t);
// Note: it's not uncommon that JNI code uses signal/sigset to install
// then restore certain signal handler (e.g. to temporarily block SIGPIPE,
// or have a SIGILL handler when detecting CPU type). When that happens,
// JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
// avoid unnecessary crash when libjsig is not preloaded, try handle signals
// that do not require siginfo/ucontext first.
if (sig == SIGPIPE || sig == SIGXFSZ) {
// allow chained handler to go first
if (os::Linux::chained_handler(sig, info, ucVoid)) {
return true;
} else {
if (PrintMiscellaneous && (WizardMode || Verbose)) {
char buf[64];
warning("Ignoring %s - see bugs 4229104 or 646499219",
os::exception_name(sig, buf, sizeof(buf)));
}
return true;
}
}
JavaThread* thread = NULL;
VMThread* vmthread = NULL;
if (os::Linux::signal_handlers_are_installed) {
if (t != NULL ){
if(t->is_Java_thread()) {
thread = (JavaThread*)t;
}
else if(t->is_VM_thread()){
vmthread = (VMThread *)t;
}
}
}
// decide if this trap can be handled by a stub
address stub = NULL;
address pc = NULL;
address npc = NULL;
//%note os_trap_1
if (info != NULL && uc != NULL && thread != NULL) {
pc = address(SIG_PC(uc));
npc = address(SIG_NPC(uc));
// Check to see if we caught the safepoint code in the
// process of write protecting the memory serialization page.
// It write enables the page immediately after protecting it
// so we can just return to retry the write.
if ((sig == SIGSEGV) && checkSerializePage(thread, (address)info->si_addr)) {
// Block current thread until the memory serialize page permission restored.
os::block_on_serialize_page_trap();
return 1;
}
if (checkPrefetch(uc, pc)) {
return 1;
}
// Handle ALL stack overflow variations here
if (sig == SIGSEGV) {
if (checkOverflow(uc, pc, (address)info->si_addr, thread, &stub)) {
return 1;
}
}
if (sig == SIGBUS &&
thread->thread_state() == _thread_in_vm &&
thread->doing_unsafe_access()) {
stub = StubRoutines::handler_for_unsafe_access();
}
if (thread->thread_state() == _thread_in_Java) {
do {
// Java thread running in Java code => find exception handler if any
// a fault inside compiled code, the interpreter, or a stub
if ((sig == SIGSEGV) && checkPollingPage(pc, (address)info->si_addr, &stub)) {
break;
}
if ((sig == SIGBUS) && checkByteBuffer(pc, &stub)) {
break;
}
if ((sig == SIGSEGV || sig == SIGBUS) &&
checkVerifyOops(pc, (address)info->si_addr, &stub)) {
break;
}
if ((sig == SIGSEGV) && checkZombie(uc, &pc, &stub)) {
break;
}
if ((sig == SIGILL) && checkICMiss(uc, &pc, &stub)) {
break;
}
if ((sig == SIGFPE) && checkFPFault(pc, info->si_code, thread, &stub)) {
break;
}
if ((sig == SIGSEGV) &&
checkNullPointer(pc, (intptr_t)info->si_addr, thread, &stub)) {
break;
}
} while (0);
// jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
// and the heap gets shrunk before the field access.
if ((sig == SIGSEGV) || (sig == SIGBUS)) {
checkFastJNIAccess(pc, &stub);
}
}
if (stub != NULL) {
// save all thread context in case we need to restore it
thread->set_saved_exception_pc(pc);
thread->set_saved_exception_npc(npc);
set_cont_address(uc, stub);
return true;
}
}
// signal-chaining
if (os::Linux::chained_handler(sig, info, ucVoid)) {
return true;
}
if (!abort_if_unrecognized) {
// caller wants another chance, so give it to him
return false;
}
if (pc == NULL && uc != NULL) {
pc = os::Linux::ucontext_get_pc((ucontext_t*)uc);
}
// unmask current signal
sigset_t newset;
sigemptyset(&newset);
sigaddset(&newset, sig);
sigprocmask(SIG_UNBLOCK, &newset, NULL);
VMError err(t, sig, pc, info, ucVoid);
err.report_and_die();
ShouldNotReachHere();
}
extern "C" JNIEXPORT int
JVM_handle_linux_signal(int sig,
siginfo_t* info,
void* ucVoid,
int abort_if_unrecognized) {
ucontext_t* uc = (ucontext_t*) ucVoid;
Thread* t = ThreadLocalStorage::get_thread_slow();
// Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
// (no destructors can be run)
os::WatcherThreadCrashProtection::check_crash_protection(sig, t);
SignalHandlerMark shm(t);
// Note: it's not uncommon that JNI code uses signal/sigset to install
// then restore certain signal handler (e.g. to temporarily block SIGPIPE,
// or have a SIGILL handler when detecting CPU type). When that happens,
// JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
// avoid unnecessary crash when libjsig is not preloaded, try handle signals
// that do not require siginfo/ucontext first.
if (sig == SIGPIPE || sig == SIGXFSZ) {
// allow chained handler to go first
if (os::Linux::chained_handler(sig, info, ucVoid)) {
return true;
} else {
if (PrintMiscellaneous && (WizardMode || Verbose)) {
char buf[64];
warning("Ignoring %s - see bugs 4229104 or 646499219",
os::exception_name(sig, buf, sizeof(buf)));
}
return true;
}
}
JavaThread* thread = NULL;
VMThread* vmthread = NULL;
if (os::Linux::signal_handlers_are_installed) {
if (t != NULL ){
if(t->is_Java_thread()) {
thread = (JavaThread*)t;
}
else if(t->is_VM_thread()){
vmthread = (VMThread *)t;
}
}
}
/*
NOTE: does not seem to work on linux.
if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
// can't decode this kind of signal
info = NULL;
} else {
assert(sig == info->si_signo, "bad siginfo");
}
*/
// decide if this trap can be handled by a stub
address stub = NULL;
address pc = NULL;
//%note os_trap_1
if (info != NULL && uc != NULL && thread != NULL) {
pc = (address) os::Linux::ucontext_get_pc(uc);
#ifdef BUILTIN_SIM
if (pc == (address) Fetch32PFI) {
uc->uc_mcontext.gregs[REG_PC] = intptr_t(Fetch32Resume) ;
return 1 ;
}
if (pc == (address) FetchNPFI) {
uc->uc_mcontext.gregs[REG_PC] = intptr_t (FetchNResume) ;
return 1 ;
}
#else
if (StubRoutines::is_safefetch_fault(pc)) {
uc->uc_mcontext.pc = intptr_t(StubRoutines::continuation_for_safefetch_fault(pc));
return 1;
}
#endif
#ifndef AMD64
// Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
// This can happen in any running code (currently more frequently in
// interpreter code but has been seen in compiled code)
if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
"to unstable signal handling in this distribution.");
}
#endif // AMD64
// Handle ALL stack overflow variations here
if (sig == SIGSEGV) {
address addr = (address) info->si_addr;
// check if fault address is within thread stack
if (addr < thread->stack_base() &&
addr >= thread->stack_base() - thread->stack_size()) {
// stack overflow
if (thread->in_stack_yellow_zone(addr)) {
thread->disable_stack_yellow_zone();
if (thread->thread_state() == _thread_in_Java) {
// Throw a stack overflow exception. Guard pages will be reenabled
// while unwinding the stack.
stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
} else {
// Thread was in the vm or native code. Return and try to finish.
return 1;
}
} else if (thread->in_stack_red_zone(addr)) {
// Fatal red zone violation. Disable the guard pages and fall through
// to handle_unexpected_exception way down below.
thread->disable_stack_red_zone();
tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
// This is a likely cause, but hard to verify. Let's just print
// it as a hint.
tty->print_raw_cr("Please check if any of your loaded .so files has "
"enabled executable stack (see man page execstack(8))");
} else {
// Accessing stack address below sp may cause SEGV if current
// thread has MAP_GROWSDOWN stack. This should only happen when
// current thread was created by user code with MAP_GROWSDOWN flag
// and then attached to VM. See notes in os_linux.cpp.
if (thread->osthread()->expanding_stack() == 0) {
thread->osthread()->set_expanding_stack();
if (os::Linux::manually_expand_stack(thread, addr)) {
thread->osthread()->clear_expanding_stack();
return 1;
}
thread->osthread()->clear_expanding_stack();
} else {
fatal("recursive segv. expanding stack.");
}
}
}
}
if (thread->thread_state() == _thread_in_Java) {
// Java thread running in Java code => find exception handler if any
// a fault inside compiled code, the interpreter, or a stub
// Handle signal from NativeJump::patch_verified_entry().
if ((sig == SIGILL || sig == SIGTRAP)
&& nativeInstruction_at(pc)->is_sigill_zombie_not_entrant()) {
if (TraceTraps) {
tty->print_cr("trap: zombie_not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
}
stub = SharedRuntime::get_handle_wrong_method_stub();
} else if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
stub = SharedRuntime::get_poll_stub(pc);
} else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
// BugId 4454115: A read from a MappedByteBuffer can fault
// here if the underlying file has been truncated.
// Do not crash the VM in such a case.
CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
nmethod* nm = (cb != NULL && cb->is_nmethod()) ? (nmethod*)cb : NULL;
if (nm != NULL && nm->has_unsafe_access()) {
stub = handle_unsafe_access(thread, pc);
}
}
else
if (sig == SIGFPE &&
(info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
stub =
SharedRuntime::
continuation_for_implicit_exception(thread,
pc,
SharedRuntime::
IMPLICIT_DIVIDE_BY_ZERO);
} else if (sig == SIGSEGV &&
!MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
// Determination of interpreter/vtable stub/compiled code null exception
stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
}
} else if (thread->thread_state() == _thread_in_vm &&
sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
thread->doing_unsafe_access()) {
stub = handle_unsafe_access(thread, pc);
}
// jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
// and the heap gets shrunk before the field access.
if ((sig == SIGSEGV) || (sig == SIGBUS)) {
address addr = JNI_FastGetField::find_slowcase_pc(pc);
if (addr != (address)-1) {
stub = addr;
}
}
// Check to see if we caught the safepoint code in the
// process of write protecting the memory serialization page.
// It write enables the page immediately after protecting it
// so we can just return to retry the write.
if ((sig == SIGSEGV) &&
os::is_memory_serialize_page(thread, (address) info->si_addr)) {
// Block current thread until the memory serialize page permission restored.
os::block_on_serialize_page_trap();
return true;
}
}
if (stub != NULL) {
// save all thread context in case we need to restore it
if (thread != NULL) thread->set_saved_exception_pc(pc);
#ifdef BUILTIN_SIM
uc->uc_mcontext.gregs[REG_PC] = (greg_t)stub;
#else
uc->uc_mcontext.pc = (__u64)stub;
#endif
return true;
}
// signal-chaining
if (os::Linux::chained_handler(sig, info, ucVoid)) {
return true;
}
if (!abort_if_unrecognized) {
// caller wants another chance, so give it to him
return false;
}
if (pc == NULL && uc != NULL) {
pc = os::Linux::ucontext_get_pc(uc);
}
// unmask current signal
sigset_t newset;
sigemptyset(&newset);
sigaddset(&newset, sig);
sigprocmask(SIG_UNBLOCK, &newset, NULL);
VMError err(t, sig, pc, info, ucVoid);
err.report_and_die();
ShouldNotReachHere();
}