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 <thread.h>
  34 #include <signal.h>
  35 
  36 void VMError::show_message_box(char *buf, int buflen) {
  37   bool yes;
  38   do {
  39     error_string(buf, buflen);
  40     int len = (int)strlen(buf);
  41     char *p = &buf[len];
  42 
  43     jio_snprintf(p, buflen - len,
  44                "\n\n"
  45                "Do you want to debug the problem?\n\n"
  46                "To debug, run 'dbx - %d'; then switch to thread " INTX_FORMAT "\n"
  47                "Enter 'yes' to launch dbx automatically (PATH must include dbx)\n"
  48                "Otherwise, press RETURN to abort...",
  49                os::current_process_id(), os::current_thread_id());
  50 
  51     yes = os::message_box("Unexpected Error", buf);
  52 
  53     if (yes) {
  54       // yes, user asked VM to launch debugger
  55       jio_snprintf(buf, buflen, "dbx - %d", os::current_process_id());
  56 
  57       os::fork_and_exec(buf);
  58       yes = false;
  59     }
  60   } while (yes);
  61 }
  62 
  63 // handle all synchronous program error signals which may happen during error
  64 // reporting. They must be unblocked, caught, handled.
  65 
  66 static const int SIGNALS[] = { SIGSEGV, SIGBUS, SIGILL, SIGFPE, SIGTRAP }; // add more if needed
  67 static const int NUM_SIGNALS = sizeof(SIGNALS) / sizeof(int);
  68 
  69 // Space for our "saved" signal flags and handlers
  70 static int resettedSigflags[NUM_SIGNALS];
  71 static address resettedSighandler[NUM_SIGNALS];
  72 
  73 static void save_signal(int idx, int sig)
  74 {
  75   struct sigaction sa;
  76   sigaction(sig, NULL, &sa);
  77   resettedSigflags[idx]   = sa.sa_flags;
  78   resettedSighandler[idx] = (sa.sa_flags & SA_SIGINFO)
  79                               ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
  80                               : CAST_FROM_FN_PTR(address, sa.sa_handler);
  81 }
  82 
  83 int VMError::get_resetted_sigflags(int sig) {
  84   for (int i = 0; i < NUM_SIGNALS; i++) {
  85     if (SIGNALS[i] == sig) {
  86       return resettedSigflags[i];
  87     }
  88   }
  89   return -1;
  90 }
  91 
  92 address VMError::get_resetted_sighandler(int sig) {
  93   for (int i = 0; i < NUM_SIGNALS; i++) {
  94     if (SIGNALS[i] == sig) {
  95       return resettedSighandler[i];
  96     }
  97   }
  98   return NULL;
  99 }
 100 
 101 static void crash_handler(int sig, siginfo_t* info, void* ucVoid) {
 102   // unmask current signal
 103   sigset_t newset;
 104   sigemptyset(&newset);
 105   sigaddset(&newset, sig);
 106   // also unmask other synchronous signals
 107   for (int i = 0; i < NUM_SIGNALS; i++) {
 108     sigaddset(&newset, SIGNALS[i]);
 109   }
 110   thr_sigsetmask(SIG_UNBLOCK, &newset, NULL);
 111 
 112   VMError err(NULL, sig, NULL, info, ucVoid);
 113   err.report_and_die();
 114 }
 115 
 116 void VMError::reset_signal_handlers() {
 117   // install signal handlers for all synchronous program error signals
 118   sigset_t newset;
 119   sigemptyset(&newset);
 120 
 121   for (int i = 0; i < NUM_SIGNALS; i++) {
 122     save_signal(i, SIGNALS[i]);
 123     os::signal(SIGNALS[i], CAST_FROM_FN_PTR(void *, crash_handler));
 124     sigaddset(&newset, SIGNALS[i]);
 125   }
 126   thr_sigsetmask(SIG_UNBLOCK, &newset, NULL);
 127 }
--- EOF ---