src/os/bsd/vm/vmError_bsd.cpp

rev 7758 : 8065895 Synchronous signals during error reporting may terminate or hang VM process
Reviewed-by: dholmes,gziemski
Contributed-by: stuefe

*** 61,73 ****
        yes = false;
      }
    } while (yes);
  }
  
  // Space for our "saved" signal flags and handlers
! static int resettedSigflags[2];
! static address resettedSighandler[2];
  
  static void save_signal(int idx, int sig)
  {
    struct sigaction sa;
    sigaction(sig, NULL, &sa);
--- 61,79 ----
        yes = false;
      }
    } while (yes);
  }
  
+ // handle all synchronous program error signals which may happen during error
+ // reporting. They must be unblocked, caught, handled. 
+ 
+ static const int SIGNALS[] = { SIGSEGV, SIGBUS, SIGILL, SIGFPE, SIGTRAP }; // add more if needed
+ static const int NUM_SIGNALS = sizeof(SIGNALS) / sizeof(int);
+ 
  // Space for our "saved" signal flags and handlers
! static int resettedSigflags[NUM_SIGNALS];
! static address resettedSighandler[NUM_SIGNALS];
  
  static void save_signal(int idx, int sig)
  {
    struct sigaction sa;
    sigaction(sig, NULL, &sa);
*** 76,115 ****
                                ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
                                : CAST_FROM_FN_PTR(address, sa.sa_handler);
  }
  
  int VMError::get_resetted_sigflags(int sig) {
!   if(SIGSEGV == sig) {
!     return resettedSigflags[0];
!   } else if(SIGBUS == sig) {
!     return resettedSigflags[1];
    }
    return -1;
  }
  
  address VMError::get_resetted_sighandler(int sig) {
!   if(SIGSEGV == sig) {
!     return resettedSighandler[0];
!   } else if(SIGBUS == sig) {
!     return resettedSighandler[1];
    }
    return NULL;
  }
  
  static void crash_handler(int sig, siginfo_t* info, void* ucVoid) {
    // unmask current signal
    sigset_t newset;
    sigemptyset(&newset);
    sigaddset(&newset, sig);
!   sigprocmask(SIG_UNBLOCK, &newset, NULL);
  
    VMError err(NULL, sig, NULL, info, ucVoid);
    err.report_and_die();
  }
  
  void VMError::reset_signal_handlers() {
!   // Save sigflags for resetted signals
!   save_signal(0, SIGSEGV);
!   save_signal(1, SIGBUS);
!   os::signal(SIGSEGV, CAST_FROM_FN_PTR(void *, crash_handler));
!   os::signal(SIGBUS, CAST_FROM_FN_PTR(void *, crash_handler));
  }
--- 82,130 ----
                                ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
                                : CAST_FROM_FN_PTR(address, sa.sa_handler);
  }
  
  int VMError::get_resetted_sigflags(int sig) {
!   for (int i = 0; i < NUM_SIGNALS; i++) {
!     if (SIGNALS[i] == sig) {
!       return resettedSigflags[i];
!     }
    }
    return -1;
  }
  
  address VMError::get_resetted_sighandler(int sig) {
!   for (int i = 0; i < NUM_SIGNALS; i++) {
!     if (SIGNALS[i] == sig) {
!       return resettedSighandler[i];
!     }
    }
    return NULL;
  }
  
  static void crash_handler(int sig, siginfo_t* info, void* ucVoid) {
    // unmask current signal
    sigset_t newset;
    sigemptyset(&newset);
    sigaddset(&newset, sig);
!   // also unmask other synchronous signals
!   for (int i = 0; i < NUM_SIGNALS; i++) {
!     sigaddset(&newset, SIGNALS[i]);
!   }
!   pthread_sigmask(SIG_UNBLOCK, &newset, NULL);
  
    VMError err(NULL, sig, NULL, info, ucVoid);
    err.report_and_die();
  }
  
  void VMError::reset_signal_handlers() {
!   // install signal handlers for all synchronous program error signals
!   sigset_t newset;
!   sigemptyset(&newset);
! 
!   for (int i = 0; i < NUM_SIGNALS; i++) {
!     save_signal(i, SIGNALS[i]);
!     os::signal(SIGNALS[i], CAST_FROM_FN_PTR(void *, crash_handler));
!     sigaddset(&newset, SIGNALS[i]);
!   }
!   pthread_sigmask(SIG_UNBLOCK, &newset, NULL);
  }