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src/hotspot/os/linux/os_linux.cpp

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 408 #undef EXTENSIONS_DIR
 409 }
 410 
 411 ////////////////////////////////////////////////////////////////////////////////
 412 // breakpoint support
 413 
 414 void os::breakpoint() {
 415   BREAKPOINT;
 416 }
 417 
 418 extern "C" void breakpoint() {
 419   // use debugger to set breakpoint here
 420 }
 421 
 422 ////////////////////////////////////////////////////////////////////////////////
 423 // signal support
 424 
 425 debug_only(static bool signal_sets_initialized = false);
 426 static sigset_t unblocked_sigs, vm_sigs;
 427 
 428 bool os::Linux::is_sig_ignored(int sig) {
 429   struct sigaction oact;
 430   sigaction(sig, (struct sigaction*)NULL, &oact);
 431   void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*,  oact.sa_sigaction)
 432                                  : CAST_FROM_FN_PTR(void*,  oact.sa_handler);
 433   if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) {
 434     return true;
 435   } else {
 436     return false;
 437   }
 438 }
 439 
 440 void os::Linux::signal_sets_init() {
 441   // Should also have an assertion stating we are still single-threaded.
 442   assert(!signal_sets_initialized, "Already initialized");
 443   // Fill in signals that are necessarily unblocked for all threads in
 444   // the VM. Currently, we unblock the following signals:
 445   // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
 446   //                         by -Xrs (=ReduceSignalUsage));
 447   // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
 448   // other threads. The "ReduceSignalUsage" boolean tells us not to alter
 449   // the dispositions or masks wrt these signals.
 450   // Programs embedding the VM that want to use the above signals for their
 451   // own purposes must, at this time, use the "-Xrs" option to prevent
 452   // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
 453   // (See bug 4345157, and other related bugs).
 454   // In reality, though, unblocking these signals is really a nop, since
 455   // these signals are not blocked by default.
 456   sigemptyset(&unblocked_sigs);
 457   sigaddset(&unblocked_sigs, SIGILL);
 458   sigaddset(&unblocked_sigs, SIGSEGV);
 459   sigaddset(&unblocked_sigs, SIGBUS);
 460   sigaddset(&unblocked_sigs, SIGFPE);
 461 #if defined(PPC64)
 462   sigaddset(&unblocked_sigs, SIGTRAP);
 463 #endif
 464   sigaddset(&unblocked_sigs, SR_signum);
 465 
 466   if (!ReduceSignalUsage) {
 467     if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
 468       sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
 469     }
 470     if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
 471       sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
 472     }
 473     if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
 474       sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
 475     }
 476   }
 477   // Fill in signals that are blocked by all but the VM thread.
 478   sigemptyset(&vm_sigs);
 479   if (!ReduceSignalUsage) {
 480     sigaddset(&vm_sigs, BREAK_SIGNAL);
 481   }
 482   debug_only(signal_sets_initialized = true);
 483 
 484 }
 485 
 486 // These are signals that are unblocked while a thread is running Java.
 487 // (For some reason, they get blocked by default.)
 488 sigset_t* os::Linux::unblocked_signals() {
 489   assert(signal_sets_initialized, "Not initialized");
 490   return &unblocked_sigs;
 491 }
 492 
 493 // These are the signals that are blocked while a (non-VM) thread is




 408 #undef EXTENSIONS_DIR
 409 }
 410 
 411 ////////////////////////////////////////////////////////////////////////////////
 412 // breakpoint support
 413 
 414 void os::breakpoint() {
 415   BREAKPOINT;
 416 }
 417 
 418 extern "C" void breakpoint() {
 419   // use debugger to set breakpoint here
 420 }
 421 
 422 ////////////////////////////////////////////////////////////////////////////////
 423 // signal support
 424 
 425 debug_only(static bool signal_sets_initialized = false);
 426 static sigset_t unblocked_sigs, vm_sigs;
 427 












 428 void os::Linux::signal_sets_init() {
 429   // Should also have an assertion stating we are still single-threaded.
 430   assert(!signal_sets_initialized, "Already initialized");
 431   // Fill in signals that are necessarily unblocked for all threads in
 432   // the VM. Currently, we unblock the following signals:
 433   // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
 434   //                         by -Xrs (=ReduceSignalUsage));
 435   // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
 436   // other threads. The "ReduceSignalUsage" boolean tells us not to alter
 437   // the dispositions or masks wrt these signals.
 438   // Programs embedding the VM that want to use the above signals for their
 439   // own purposes must, at this time, use the "-Xrs" option to prevent
 440   // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
 441   // (See bug 4345157, and other related bugs).
 442   // In reality, though, unblocking these signals is really a nop, since
 443   // these signals are not blocked by default.
 444   sigemptyset(&unblocked_sigs);
 445   sigaddset(&unblocked_sigs, SIGILL);
 446   sigaddset(&unblocked_sigs, SIGSEGV);
 447   sigaddset(&unblocked_sigs, SIGBUS);
 448   sigaddset(&unblocked_sigs, SIGFPE);
 449 #if defined(PPC64)
 450   sigaddset(&unblocked_sigs, SIGTRAP);
 451 #endif
 452   sigaddset(&unblocked_sigs, SR_signum);
 453 
 454   if (!ReduceSignalUsage) {
 455     if (!os::Posix::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
 456       sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
 457     }
 458     if (!os::Posix::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
 459       sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
 460     }
 461     if (!os::Posix::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
 462       sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
 463     }
 464   }
 465   // Fill in signals that are blocked by all but the VM thread.
 466   sigemptyset(&vm_sigs);
 467   if (!ReduceSignalUsage) {
 468     sigaddset(&vm_sigs, BREAK_SIGNAL);
 469   }
 470   debug_only(signal_sets_initialized = true);
 471 
 472 }
 473 
 474 // These are signals that are unblocked while a thread is running Java.
 475 // (For some reason, they get blocked by default.)
 476 sigset_t* os::Linux::unblocked_signals() {
 477   assert(signal_sets_initialized, "Not initialized");
 478   return &unblocked_sigs;
 479 }
 480 
 481 // These are the signals that are blocked while a (non-VM) thread is


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