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

   1 /*
   2  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "runtime/arguments.hpp"
  27 #include "runtime/os.hpp"
  28 #include "runtime/thread.hpp"
  29 #include "utilities/vmError.hpp"
  30 
  31 #include <sys/types.h>
  32 #include <sys/wait.h>
  33 #include <sys/syscall.h>
  34 #include <unistd.h>
  35 #include <signal.h>
  36 
  37 void VMError::show_message_box(char *buf, int buflen) {
  38   bool yes;
  39   do {
  40     error_string(buf, buflen);
  41     int len = (int)strlen(buf);
  42     char *p = &buf[len];
  43 
  44     jio_snprintf(p, buflen - len,
  45                "\n\n"
  46                "Do you want to debug the problem?\n\n"
  47                "To debug, run 'gdb /proc/%d/exe %d'; then switch to thread " INTX_FORMAT " (" INTPTR_FORMAT ")\n"
  48                "Enter 'yes' to launch gdb automatically (PATH must include gdb)\n"
  49                "Otherwise, press RETURN to abort...",
  50                os::current_process_id(), os::current_process_id(),
  51                os::current_thread_id(), os::current_thread_id());
  52 
  53     yes = os::message_box("Unexpected Error", buf);
  54 
  55     if (yes) {
  56       // yes, user asked VM to launch debugger
  57       jio_snprintf(buf, buflen, "gdb /proc/%d/exe %d",
  58                    os::current_process_id(), os::current_process_id());
  59 
  60       os::fork_and_exec(buf);
  61       yes = false;
  62     }
  63   } while (yes);
  64 }
  65 
  66 // handle all synchronous program error signals which may happen during error
  67 // reporting. They must be unblocked, caught, handled. 
  68 
  69 static const int SIGNALS[] = { SIGSEGV, SIGBUS, SIGILL, SIGFPE, SIGTRAP }; // add more if needed
  70 static const int NUM_SIGNALS = sizeof(SIGNALS) / sizeof(int);
  71 
  72 // Space for our "saved" signal flags and handlers
  73 static int resettedSigflags[NUM_SIGNALS];
  74 static address resettedSighandler[NUM_SIGNALS];
  75 
  76 static void save_signal(int idx, int sig)
  77 {
  78   struct sigaction sa;
  79   sigaction(sig, NULL, &sa);
  80   resettedSigflags[idx]   = sa.sa_flags;
  81   resettedSighandler[idx] = (sa.sa_flags & SA_SIGINFO)
  82                               ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
  83                               : CAST_FROM_FN_PTR(address, sa.sa_handler);
  84 }
  85 
  86 int VMError::get_resetted_sigflags(int sig) {
  87   for (int i = 0; i < NUM_SIGNALS; i++) {
  88     if (SIGNALS[i] == sig) {
  89       return resettedSigflags[i];
  90     }
  91   }
  92   return -1;
  93 }
  94 
  95 address VMError::get_resetted_sighandler(int sig) {
  96   for (int i = 0; i < NUM_SIGNALS; i++) {
  97     if (SIGNALS[i] == sig) {
  98       return resettedSighandler[i];
  99     }
 100   }
 101   return NULL;
 102 }
 103 
 104 static void crash_handler(int sig, siginfo_t* info, void* ucVoid) {
 105   // unmask current signal
 106   sigset_t newset;
 107   sigemptyset(&newset);
 108   sigaddset(&newset, sig);
 109   // also unmask other synchronous signals
 110   for (int i = 0; i < NUM_SIGNALS; i++) {
 111     sigaddset(&newset, SIGNALS[i]);
 112   }
 113   pthread_sigmask(SIG_UNBLOCK, &newset, NULL);
 114 
 115   VMError err(NULL, sig, NULL, info, ucVoid);
 116   err.report_and_die();
 117 }
 118 
 119 void VMError::reset_signal_handlers() {
 120   // install signal handlers for all synchronous program error signals
 121   sigset_t newset;
 122   sigemptyset(&newset);
 123 
 124   for (int i = 0; i < NUM_SIGNALS; i++) {
 125     save_signal(i, SIGNALS[i]);
 126     os::signal(SIGNALS[i], CAST_FROM_FN_PTR(void *, crash_handler));
 127     sigaddset(&newset, SIGNALS[i]);
 128   }
 129   pthread_sigmask(SIG_UNBLOCK, &newset, NULL);
 130 }
--- EOF ---