/*
 * Copyright (c) 2006 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. Neither the name of The DragonFly Project 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 HOLDERS 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 "opt_ddb.h"
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/reboot.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <ddb/ddb.h>

#include <sys/thread2.h>
#include <sys/lwp.h>

#include <machine/trap.h>
#include <machine/md_var.h>
#include <machine/segments.h>
#include <machine/cpu.h>
#include <machine/smp.h>

#include <err.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>

int _ucodesel = GSEL(GUCODE_SEL, SEL_UPL);
int _udatasel = GSEL(GUDATA_SEL, SEL_UPL);

static void exc_segfault(int signo, siginfo_t *info, void *ctx);
#ifdef DDB
static void exc_debugger(int signo, siginfo_t *info, void *ctx);
#endif

/*
 * IPIs are 'fast' interrupts, so we deal with them directly from our
 * signal handler.
 *
 * WARNING: Signals are not physically disabled here so we have to enter
 * our critical section before bumping gd_intr_nesting_level or another
 * interrupt can come along and get really confused.
 */
static
void
ipisig(int nada, siginfo_t *info, void *ctxp)
{
        globaldata_t gd = mycpu;
        thread_t td = gd->gd_curthread;
        int save;

        save = errno;
        if (td->td_critcount == 0) {
                crit_enter_quick(td);
                ++gd->gd_cnt.v_ipi;
                ++gd->gd_intr_nesting_level;
                atomic_swap_int(&gd->gd_npoll, 0);
                lwkt_process_ipiq();
                --gd->gd_intr_nesting_level;
                crit_exit_quick(td);
        } else {
                need_ipiq();
        }
        errno = save;
}

/*
 * Unconditionally stop or restart a cpu.
 *
 * Note: cpu_mask_all_signals() masks all signals except SIGXCPU itself.
 * SIGXCPU itself is blocked on entry to stopsig() by the signal handler
 * itself.
 *
 * WARNING: Signals are not physically disabled here so we have to enter
 * our critical section before bumping gd_intr_nesting_level or another
 * interrupt can come along and get really confused.
 */
static
void
stopsig(int nada, siginfo_t *info, void *ctxp)
{
        globaldata_t gd = mycpu;
        thread_t td = gd->gd_curthread;
        sigset_t ss;
        int save;

        save = errno;
        sigemptyset(&ss);
        sigaddset(&ss, SIGALRM);
        sigaddset(&ss, SIGIO);
        sigaddset(&ss, SIGURG);
        sigaddset(&ss, SIGQUIT);
        sigaddset(&ss, SIGUSR1);
        sigaddset(&ss, SIGUSR2);
        sigaddset(&ss, SIGTERM);
        sigaddset(&ss, SIGWINCH);

        crit_enter_quick(td);
        ++gd->gd_intr_nesting_level;
        while (CPUMASK_TESTMASK(stopped_cpus, gd->gd_cpumask)) {
                sigsuspend(&ss);
        }
        --gd->gd_intr_nesting_level;
        crit_exit_quick(td);

        errno = save;
}

/*
 * SIGIO is used by cothreads to signal back into the virtual kernel.
 */
static
void
kqueuesig(int nada, siginfo_t *info, void *ctxp)
{
        globaldata_t gd = mycpu;
        thread_t td = gd->gd_curthread;
        int save;

        save = errno;
        if (td->td_critcount == 0) {
                crit_enter_quick(td);
                ++gd->gd_intr_nesting_level;
                cpu_ccfence();
                kqueue_intr(NULL);
                cpu_ccfence();
                --gd->gd_intr_nesting_level;
                crit_exit_quick(td);
        } else {
                need_kqueue();
        }
        errno = save;
}

static
void
timersig(int nada, siginfo_t *info, void *ctxp)
{
        globaldata_t gd = mycpu;
        thread_t td = gd->gd_curthread;
        int save;

        save = errno;
        if (td->td_critcount == 0) {
                crit_enter_quick(td);
                ++gd->gd_intr_nesting_level;
                cpu_ccfence();
                vktimer_intr(NULL);
                cpu_ccfence();
                --gd->gd_intr_nesting_level;
                crit_exit_quick(td);
        } else {
                need_timer();
        }
        errno = save;
}

static
void
cosig(int nada, siginfo_t *info, void *ctxp)
{
        int save;

        save = errno;
        /* handles critical section checks */
        signalintr(1);
        errno = save;
}

static
void
infosig(int nada, siginfo_t *info, void *ctxp)
{
        ucontext_t *ctx = ctxp;
        char buf[256];
        int save;

        save = errno;
        snprintf(buf, sizeof(buf), "lwp %d pc=%p sp=%p\n",
                (lwpid_t)lwp_gettid(),
                (void *)(intptr_t)ctx->uc_mcontext.mc_rip,
                (void *)(intptr_t)ctx->uc_mcontext.mc_rsp);
        write(2, buf, strlen(buf));
        errno = save;
}

void
init_exceptions(void)
{
        struct sigaction sa;

        bzero(&sa, sizeof(sa));
        sa.sa_sigaction = exc_segfault;
        sa.sa_flags |= SA_SIGINFO | SA_NODEFER;
        sigemptyset(&sa.sa_mask);
        sigaction(SIGBUS, &sa, NULL);
        sigaction(SIGSEGV, &sa, NULL);
        sigaction(SIGTRAP, &sa, NULL);
        sigaction(SIGFPE, &sa, NULL);

        sa.sa_flags &= ~SA_NODEFER;

#ifdef DDB
        sa.sa_sigaction = exc_debugger;
        sigaction(SIGQUIT, &sa, NULL);
#endif
        sa.sa_sigaction = ipisig;
        sigaction(SIGUSR1, &sa, NULL);

        sa.sa_sigaction = stopsig;
        sigaction(SIGXCPU, &sa, NULL);

        sa.sa_sigaction = kqueuesig;
        sigaction(SIGIO, &sa, NULL);

        sa.sa_sigaction = timersig;
        sigaction(SIGURG, &sa, NULL);

        sa.sa_sigaction = cosig;
        sigaction(SIGALRM, &sa, NULL);

        sa.sa_sigaction = infosig;
        sigaction(SIGINFO, &sa, NULL);
}

/*
 * This function handles a segmentation fault.
 *
 * XXX We assume that trapframe is a subset of ucontext.  It is as of
 *     this writing.
 */
static void
exc_segfault(int signo, siginfo_t *info, void *ctxp)
{
        ucontext_t *ctx = ctxp;
        int save;

        save = errno;
        kern_trap((struct trapframe *)&ctx->uc_mcontext.mc_rdi);
        splz();
        errno = save;
}

#ifdef DDB

static void
exc_debugger(int signo, siginfo_t *info, void *ctxp)
{
        ucontext_t *ctx = ctxp;
        int save;

        save = errno;
        kprintf("CAUGHT SIG %d RIP %08lx RSP %08lx TD %p\n",
                signo,
                ctx->uc_mcontext.mc_rip,
                ctx->uc_mcontext.mc_rsp,
                curthread);
        Debugger("interrupt from console");
        errno = save;
}

#endif