1 /*
   2  * Copyright (c) 2003, 2018, 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 "memory/metaspaceShared.hpp"
  27 #include "runtime/arguments.hpp"
  28 #include "runtime/os.hpp"
  29 #include "runtime/thread.hpp"
  30 #include "utilities/vmError.hpp"
  31 
  32 #include <sys/types.h>
  33 #include <sys/wait.h>
  34 #include <signal.h>
  35 
  36 #ifdef LINUX
  37 #include <sys/syscall.h>
  38 #include <unistd.h>
  39 #endif
  40 #ifdef SOLARIS
  41 #include <thread.h>
  42 #endif
  43 #ifdef AIX
  44 #include <unistd.h>
  45 #endif
  46 #ifdef BSD
  47 #include <sys/syscall.h>
  48 #include <unistd.h>
  49 #endif
  50 
  51 
  52 // handle all synchronous program error signals which may happen during error
  53 // reporting. They must be unblocked, caught, handled.
  54 
  55 static const int SIGNALS[] = { SIGSEGV, SIGBUS, SIGILL, SIGFPE, SIGTRAP }; // add more if needed
  56 static const int NUM_SIGNALS = sizeof(SIGNALS) / sizeof(int);
  57 
  58 // Space for our "saved" signal flags and handlers
  59 static int resettedSigflags[NUM_SIGNALS];
  60 static address resettedSighandler[NUM_SIGNALS];
  61 
  62 // Needed for cancelable steps.
  63 static volatile pthread_t reporter_thread_id;
  64 
  65 void VMError::reporting_started() {
  66   // record pthread id of reporter thread.
  67   reporter_thread_id = ::pthread_self();
  68 }
  69 
  70 void VMError::interrupt_reporting_thread() {
  71   // We misuse SIGILL here, but it does not really matter. We need
  72   //  a signal which is handled by crash_handler and not likely to
  73   //  occurr during error reporting itself.
  74   ::pthread_kill(reporter_thread_id, SIGILL);
  75 }
  76 
  77 static void save_signal(int idx, int sig)
  78 {
  79   struct sigaction sa;
  80   sigaction(sig, NULL, &sa);
  81   resettedSigflags[idx]   = sa.sa_flags;
  82   resettedSighandler[idx] = (sa.sa_flags & SA_SIGINFO)
  83                               ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
  84                               : CAST_FROM_FN_PTR(address, sa.sa_handler);
  85 }
  86 
  87 int VMError::get_resetted_sigflags(int sig) {
  88   for (int i = 0; i < NUM_SIGNALS; i++) {
  89     if (SIGNALS[i] == sig) {
  90       return resettedSigflags[i];
  91     }
  92   }
  93   return -1;
  94 }
  95 
  96 address VMError::get_resetted_sighandler(int sig) {
  97   for (int i = 0; i < NUM_SIGNALS; i++) {
  98     if (SIGNALS[i] == sig) {
  99       return resettedSighandler[i];
 100     }
 101   }
 102   return NULL;
 103 }
 104 
 105 static void crash_handler(int sig, siginfo_t* info, void* ucVoid) {
 106   // unmask current signal
 107   sigset_t newset;
 108   sigemptyset(&newset);
 109   sigaddset(&newset, sig);
 110   // also unmask other synchronous signals
 111   for (int i = 0; i < NUM_SIGNALS; i++) {
 112     sigaddset(&newset, SIGNALS[i]);
 113   }
 114   os::Posix::unblock_thread_signal_mask(&newset);
 115 
 116   // support safefetch faults in error handling
 117   ucontext_t* const uc = (ucontext_t*) ucVoid;
 118   address pc = (uc != NULL) ? os::Posix::ucontext_get_pc(uc) : NULL;
 119 
 120   // Correct pc for SIGILL, SIGFPE (see JDK-8176872)
 121   if (sig == SIGILL || sig == SIGFPE) {
 122     pc = (address) info->si_addr;
 123   }
 124 
 125   if (uc && pc && StubRoutines::is_safefetch_fault(pc)) {
 126     os::Posix::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
 127     return;
 128   }
 129 
 130   VMError::report_and_die(NULL, sig, pc, info, ucVoid);
 131 }
 132 
 133 void VMError::reset_signal_handlers() {
 134   // install signal handlers for all synchronous program error signals
 135   sigset_t newset;
 136   sigemptyset(&newset);
 137 
 138   for (int i = 0; i < NUM_SIGNALS; i++) {
 139     save_signal(i, SIGNALS[i]);
 140     os::signal(SIGNALS[i], CAST_FROM_FN_PTR(void *, crash_handler));
 141     sigaddset(&newset, SIGNALS[i]);
 142   }
 143   os::Posix::unblock_thread_signal_mask(&newset);
 144 
 145 }
 146 
 147 // Write a hint to the stream in case siginfo relates to a segv/bus error
 148 // and the offending address points into CDS archive.
 149 void VMError::check_failing_cds_access(outputStream* st, const void* siginfo) {
 150 #if INCLUDE_CDS
 151   if (siginfo && UseSharedSpaces) {
 152     const siginfo_t* const si = (siginfo_t*)siginfo;
 153     if (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) {
 154       const void* const fault_addr = si->si_addr;
 155       if (fault_addr != NULL) {
 156         if (MetaspaceShared::is_in_shared_metaspace(fault_addr)) {
 157           st->print("Error accessing class data sharing archive. "
 158             "Mapped file inaccessible during execution, possible disk/network problem.");
 159         }
 160       }
 161     }
 162   }
 163 #endif
 164 }
 165