init_signals.cc

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/*
 * Copyright (c) 2012, 2015 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Copyright (c) 2000-2005 The Regents of The University of Michigan
 * Copyright (c) 2008 The Hewlett-Packard Development Company
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "sim/init_signals.hh"

#include <sys/types.h>
#include <unistd.h>

#include <csignal>
#include <iostream>
#include <string>

#if defined(__FreeBSD__)
#include <sys/param.h>

#endif

#include "base/atomicio.hh"
#include "base/cprintf.hh"
#include "base/logging.hh"
#include "sim/async.hh"
#include "sim/backtrace.hh"
#include "sim/core.hh"
#include "sim/eventq.hh"

using namespace std;

// Use an separate stack for fatal signal handlers
static uint8_t fatalSigStack[2 * SIGSTKSZ];

static bool
setupAltStack()
{
    stack_t stack;
#if defined(__FreeBSD__) && (__FreeBSD_version < 1100097)
    stack.ss_sp = (char *)fatalSigStack;
#else
    stack.ss_sp = fatalSigStack;
#endif
    stack.ss_size = sizeof(fatalSigStack);
    stack.ss_flags = 0;

    return sigaltstack(&stack, NULL) == 0;
}

static void
installSignalHandler(int signal, void (*handler)(int sigtype),
                     int flags = SA_RESTART)
{
    struct sigaction sa;

    memset(&sa, 0, sizeof(sa));
    sigemptyset(&sa.sa_mask);
    sa.sa_handler = handler;
    sa.sa_flags = flags;

    if (sigaction(signal, &sa, NULL) == -1)
        panic("Failed to setup handler for signal %i\n", signal);
}

static void
raiseFatalSignal(int signo)
{
    // The signal handler should have been reset and unmasked (it was
    // registered with SA_RESETHAND | SA_NODEFER), just raise the
    // signal again to invoke the default handler.
    pthread_kill(pthread_self(), signo);

    // Something is really wrong if the process is alive at this
    // point, manually try to exit it.
    STATIC_ERR("Failed to execute default signal handler!\n");
    _exit(127);
}

void
dumpStatsHandler(int sigtype)
{
    async_event = true;
    async_statdump = true;
    /* Wake up some event queue to handle event */
    getEventQueue(0)->wakeup();
}

void
dumprstStatsHandler(int sigtype)
{
    async_event = true;
    async_statdump = true;
    async_statreset = true;
    /* Wake up some event queue to handle event */
    getEventQueue(0)->wakeup();
}

void
exitNowHandler(int sigtype)
{
    async_event = true;
    async_exit = true;
    /* Wake up some event queue to handle event */
    getEventQueue(0)->wakeup();
}

void
abortHandler(int sigtype)
{
    const EventQueue *const eq(curEventQueue());
    if (eq) {
        ccprintf(cerr, "Program aborted at tick %llu\n", eq->getCurTick());
    } else {
        STATIC_ERR("Program aborted\n\n");
    }

    print_backtrace();
    raiseFatalSignal(sigtype);
}

static void
segvHandler(int sigtype)
{
    STATIC_ERR("gem5 has encountered a segmentation fault!\n\n");

    print_backtrace();
    raiseFatalSignal(SIGSEGV);
}

// Handle SIGIO
static void
ioHandler(int sigtype)
{
    async_event = true;
    async_io = true;
    /* Wake up some event queue to handle event */
    getEventQueue(0)->wakeup();
}

/*
 * M5 can do several special things when various signals are sent.
 * None are mandatory.
 */
void
initSignals()
{
    // Floating point exceptions may happen on misspeculated paths, so
    // ignore them
    signal(SIGFPE, SIG_IGN);

    // Dump intermediate stats
    installSignalHandler(SIGUSR1, dumpStatsHandler);

    // Dump intermediate stats and reset them
    installSignalHandler(SIGUSR2, dumprstStatsHandler);

    // Exit cleanly on Interrupt (Ctrl-C)
    installSignalHandler(SIGINT, exitNowHandler);

    // Print the current cycle number and a backtrace on abort. Make
    // sure the signal is unmasked and the handler reset when a signal
    // is delivered to be able to invoke the default handler.
    installSignalHandler(SIGABRT, abortHandler, SA_RESETHAND | SA_NODEFER);

    // Setup a SIGSEGV handler with a private stack
    if (setupAltStack()) {
        installSignalHandler(SIGSEGV, segvHandler,
                             SA_RESETHAND | SA_NODEFER | SA_ONSTACK);
    } else {
        warn("Failed to setup stack for SIGSEGV handler, "
             "using default signal handler.\n");
    }

    // Install a SIGIO handler to handle asynchronous file IO. See the
    // PollQueue class.
    installSignalHandler(SIGIO, ioHandler);
}