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/*

 * Copyright (c) 2008 Jiri Svoboda

 * 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.

 */

/** @addtogroup generic

 * @{

 */

/**

 * @file

 * @brief   Udebug.

 */

#include <synch/waitq.h>

#include <console/klog.h>

#include <udebug/udebug.h>

#include <errno.h>

#include <arch.h>

void udebug_task_init(udebug_task_t *ut)

{

    mutex_initialize(&ut->lock);

    ut->dt_state = UDEBUG_TS_INACTIVE;

    ut->begin_call = NULL;

    ut->not_stoppable_count = 0;

    ut->evmask = 0;

}

static void udebug_wait_for_go(waitq_t *wq)

{

    int rc;

    ipl_t ipl;

    ipl = waitq_sleep_prepare(wq);

    wq->missed_wakeups = 0; /* Enforce blocking. */

    rc = waitq_sleep_timeout_unsafe(wq, SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE);

    waitq_sleep_finish(wq, rc, ipl);

}

void udebug_stoppable_begin(void)

{

    int nsc;

    call_t *db_call, *go_call;

    ipl_t ipl;

    ASSERT(THREAD);

    ASSERT(TASK);

    mutex_lock(&TASK->udebug.lock);

    nsc = --TASK->udebug.not_stoppable_count;

    if (TASK->udebug.dt_state == UDEBUG_TS_BEGINNING) {

        klog_printf("udebug_stoppable_begin");

        klog_printf(" - nsc := %d", nsc);

    }

    if (TASK->udebug.dt_state == UDEBUG_TS_BEGINNING && nsc == 0) {

        /*

         * This was the last non-stoppable thread. Reply to

         * DEBUG_BEGIN call.

         */

        db_call = TASK->udebug.begin_call;

        ASSERT(db_call);

        /* Lock order OK, THREAD->debug_lock is after TASK->udebug.lock */

        ipl = interrupts_disable();

        spinlock_lock(&THREAD->debug_lock);

        THREAD->debug_stoppable = true;

        spinlock_unlock(&THREAD->debug_lock);

        interrupts_restore(ipl);

        TASK->udebug.dt_state = UDEBUG_TS_ACTIVE;

        TASK->udebug.begin_call = NULL;

        mutex_unlock(&TASK->udebug.lock);

        IPC_SET_RETVAL(db_call->data, 0);

        //klog_printf("udebug_stoppable_begin/ipc_answer");

        ipc_answer(&TASK->answerbox, db_call);     

    } else if (TASK->udebug.dt_state == UDEBUG_TS_ACTIVE) {

        /*

         * Active debugging session

         */

        /* Lock order OK, THREAD->debug_lock is after TASK->udebug.lock */

        ipl = interrupts_disable();

        spinlock_lock(&THREAD->debug_lock);

        THREAD->debug_stoppable = true;

        if (THREAD->debug_active && THREAD->debug_stop) {

            /*

             * Thread was requested to stop - answer go call

             */

            /* Make sure nobody takes this call away from us */

            go_call = THREAD->debug_go_call;

            THREAD->debug_go_call = NULL;

            ASSERT(go_call);

            IPC_SET_RETVAL(go_call->data, 0);

            IPC_SET_ARG1(go_call->data, UDEBUG_EVENT_STOP);

            THREAD->cur_event = UDEBUG_EVENT_STOP;

            spinlock_unlock(&THREAD->debug_lock);

            interrupts_restore(ipl);

                ipc_answer(&TASK->answerbox, go_call);

                mutex_unlock(&TASK->udebug.lock);

        } else {

            /*

             * No stop request - nothing happens.

             */

            spinlock_unlock(&THREAD->debug_lock);

            interrupts_restore(ipl);

                mutex_unlock(&TASK->udebug.lock);

        }

    } else {

        /*

         * All other cases - nothing special happens.

         */

        /* Lock order OK, THREAD->debug_lock is after TASK->udebug.lock */

        ipl = interrupts_disable();

        spinlock_lock(&THREAD->debug_lock);

        THREAD->debug_stoppable = true;

        spinlock_unlock(&THREAD->debug_lock);

        interrupts_restore(ipl);

            mutex_unlock(&TASK->udebug.lock);

    }

}

void udebug_stoppable_end(void)

{

    ipl_t ipl;

restart:

    mutex_lock(&TASK->udebug.lock);

    /* Lock order OK, THREAD->debug_lock is after TASK->udebug.lock */

    ipl = interrupts_disable();

    spinlock_lock(&THREAD->debug_lock);

    if (TASK->udebug.dt_state == UDEBUG_TS_ACTIVE) {

        //klog_printf("udebug_stoppable_end");

        //klog_printf("debug_stop=%d", THREAD->debug_stop);

    }

    if (THREAD->debug_active &&

        THREAD->debug_stop == true) {

        TASK->udebug.begin_call = NULL;

        spinlock_unlock(&THREAD->debug_lock);

        interrupts_restore(ipl);

        mutex_unlock(&TASK->udebug.lock);

        udebug_wait_for_go(&THREAD->go_wq);

        goto restart;

        /* must try again - have to lose stoppability atomically */

    } else {

        ++TASK->udebug.not_stoppable_count;

        THREAD->debug_stoppable = false;

        spinlock_unlock(&THREAD->debug_lock);

        interrupts_restore(ipl);

        mutex_unlock(&TASK->udebug.lock);

    }

}

/** Upon being scheduled to run, check if the current thread should stop.

 *

 * This function is called from clock(). Preemption is enabled.

 * interrupts are disabled, but since this is called after

 * being scheduled-in, we can enable them, if we're careful enough

 * not to allow arbitrary recursion.

 */

void udebug_before_thread_runs(void)

{

    ipl_t ipl;

    /* This will happen if we get preempted inside this function. */

    if (THREAD->debug_in_before_thread_runs)

        return;

    THREAD->debug_in_before_thread_runs = true;

    ipl = interrupts_enable();

    /* Now we're free to do whatever we need (lock mutexes, sleep, etc.) */

    /* Check if we're supposed to stop */

    udebug_stoppable_begin();

    udebug_stoppable_end();

    interrupts_restore(ipl);

    THREAD->debug_in_before_thread_runs = false;

}

void udebug_syscall_event(unative_t a1, unative_t a2, unative_t a3,

    unative_t a4, unative_t a5, unative_t a6, unative_t id, unative_t rc,

    bool end_variant)

{

    call_t *call;

    ipl_t ipl;

    udebug_event_t etype;

    etype = end_variant ? UDEBUG_EVENT_SYSCALL_E : UDEBUG_EVENT_SYSCALL_B;

    mutex_lock(&TASK->udebug.lock);

    ipl = interrupts_disable();

    spinlock_lock(&THREAD->debug_lock);

    /* Must only generate events when in debugging session and have go */

    if (THREAD->debug_active != true ||

        THREAD->debug_stop == true ||

        (TASK->udebug.evmask & UDEBUG_EVMASK(etype)) == 0) {

        spinlock_unlock(&THREAD->debug_lock);

        interrupts_restore(ipl);

        mutex_unlock(&TASK->udebug.lock);

        return;

    }

    //klog_printf("udebug_syscall_event");

    call = THREAD->debug_go_call;

    THREAD->debug_go_call = NULL;

    IPC_SET_RETVAL(call->data, 0);

    IPC_SET_ARG1(call->data, etype);

    IPC_SET_ARG2(call->data, id);

    IPC_SET_ARG3(call->data, rc);

    //klog_printf("udebug_syscall_event/ipc_answer");

    THREAD->syscall_args[0] = a1;

    THREAD->syscall_args[1] = a2;

    THREAD->syscall_args[2] = a3;

    THREAD->syscall_args[3] = a4;

    THREAD->syscall_args[4] = a5;

    THREAD->syscall_args[5] = a6;

    /*

     * Make sure debug_stop is true when going to sleep

     * in case we get woken up by DEBUG_END. (At which

     * point it must be back to the initial true value).

     */

    THREAD->debug_stop = true;

    THREAD->cur_event = etype;

    spinlock_unlock(&THREAD->debug_lock);

    interrupts_restore(ipl);

    ipc_answer(&TASK->answerbox, call);

    mutex_unlock(&TASK->udebug.lock);

    udebug_wait_for_go(&THREAD->go_wq);

}

void udebug_thread_b_event(struct thread *t)

{

    call_t *call;

    ipl_t ipl;

    mutex_lock(&TASK->udebug.lock);

    ipl = interrupts_disable();

    spinlock_lock(&THREAD->debug_lock);

    klog_printf("udebug_thread_b_event");

    klog_printf("- check state");

    /* Must only generate events when in debugging session */

    if (THREAD->debug_active != true) {

        klog_printf("- debug_active: %s, debug_stop: %s",

            THREAD->debug_active ? "yes(+)" : "no(-)",

            THREAD->debug_stop ? "yes(-)" : "no(+)");

        spinlock_unlock(&THREAD->debug_lock);

        interrupts_restore(ipl);

        mutex_unlock(&TASK->udebug.lock);

        return;

    }

    klog_printf("- trigger event");

    call = THREAD->debug_go_call;

    THREAD->debug_go_call = NULL;

    IPC_SET_RETVAL(call->data, 0);

    IPC_SET_ARG1(call->data, UDEBUG_EVENT_THREAD_B);

    IPC_SET_ARG2(call->data, (unative_t)t);

    /*

     * Make sure debug_stop is true when going to sleep

     * in case we get woken up by DEBUG_END. (At which

     * point it must be back to the initial true value).

     */

    THREAD->debug_stop = true;

    THREAD->cur_event = UDEBUG_EVENT_THREAD_B;

    spinlock_unlock(&THREAD->debug_lock);

    interrupts_restore(ipl);

    ipc_answer(&TASK->answerbox, call);

    mutex_unlock(&TASK->udebug.lock);

    klog_printf("- sleep");

    udebug_wait_for_go(&THREAD->go_wq);

}

void udebug_thread_e_event(void)

{

    call_t *call;

    ipl_t ipl;

    mutex_lock(&TASK->udebug.lock);

    ipl = interrupts_disable();

    spinlock_lock(&THREAD->debug_lock);

    klog_printf("udebug_thread_e_event");

    klog_printf("- check state");

    /* Must only generate events when in debugging session */

    if (THREAD->debug_active != true) {

        klog_printf("- debug_active: %s, debug_stop: %s",

            THREAD->debug_active ? "yes(+)" : "no(-)",

            THREAD->debug_stop ? "yes(-)" : "no(+)");

        spinlock_unlock(&THREAD->debug_lock);

        interrupts_restore(ipl);

        mutex_unlock(&TASK->udebug.lock);

        return;

    }

    klog_printf("- trigger event");

    call = THREAD->debug_go_call;

    THREAD->debug_go_call = NULL;

    IPC_SET_RETVAL(call->data, 0);

    IPC_SET_ARG1(call->data, UDEBUG_EVENT_THREAD_E);

    /* Prevent any further debug activity in thread */

    THREAD->debug_active = false;

    THREAD->cur_event = 0;      /* none */

    THREAD->debug_stop = true;  /* set to initial value */

    spinlock_unlock(&THREAD->debug_lock);

    interrupts_restore(ipl);

    ipc_answer(&TASK->answerbox, call);

    mutex_unlock(&TASK->udebug.lock);

    /* This event does not sleep - debugging has finished in this thread */

}

static void breakpoint_trap_event(uintptr_t addr, udebug_event_t etype)

{

    call_t *call;

    ipl_t ipl;

    mutex_lock(&TASK->udebug.lock);

    ipl = interrupts_disable();

    spinlock_lock(&THREAD->debug_lock);

    /* Must only generate events when in debugging session and have go */

    if (THREAD->debug_active != true ||

        THREAD->debug_stop == true ||

        (TASK->udebug.evmask & UDEBUG_EVMASK(etype)) == 0) {

        spinlock_unlock(&THREAD->debug_lock);

        interrupts_restore(ipl);

        mutex_unlock(&TASK->udebug.lock);

        return;

    }

    klog_printf("udebug_breakpoint/trap_event");

    call = THREAD->debug_go_call;

    THREAD->debug_go_call = NULL;

    IPC_SET_RETVAL(call->data, 0);

    IPC_SET_ARG1(call->data, etype);

    IPC_SET_ARG2(call->data, addr);

    /*

     * Make sure debug_stop is true when going to sleep

     * in case we get woken up by DEBUG_END. (At which

     * point it must be back to the initial true value).

     */

    THREAD->debug_stop = true;

    THREAD->cur_event = etype;

    spinlock_unlock(&THREAD->debug_lock);

    interrupts_restore(ipl);

    klog_printf("- send answer");

    ipc_answer(&TASK->answerbox, call);

    mutex_unlock(&TASK->udebug.lock);

    udebug_wait_for_go(&THREAD->go_wq);

}

void udebug_breakpoint_event(uintptr_t addr)

{

    breakpoint_trap_event(addr, UDEBUG_EVENT_BREAKPOINT);

}

void udebug_trap_event(uintptr_t addr)

{

    breakpoint_trap_event(addr, UDEBUG_EVENT_TRAP);

}

/**

 * Terminate task debugging session.

 *

 * \param ta->udebug.lock must be already locked.

 * \return Zero on success or negative error code.

 */

int udebug_task_cleanup(struct task *ta)

{

    thread_t *t;

    link_t *cur;

    int flags;

    ipl_t ipl;

    klog_printf("udebug_task_cleanup()");

    klog_printf("task %llu", ta->taskid);

    if (ta->udebug.dt_state == UDEBUG_TS_BEGINNING &&

        ta->udebug.dt_state != UDEBUG_TS_ACTIVE) {

        klog_printf("udebug_task_cleanup(): task not being debugged");

        return EINVAL;

    }

    /* Finish debugging of all userspace threads */

    for (cur = ta->th_head.next; cur != &ta->th_head; cur = cur->next) {

        t = list_get_instance(cur, thread_t, th_link);

        ipl = interrupts_disable();

        spinlock_lock(&t->debug_lock);

        spinlock_lock(&t->lock);

        flags = t->flags;

        spinlock_unlock(&t->lock);

        /* Only process userspace threads */

        if ((flags & THREAD_FLAG_USPACE) != 0) {

            /* Prevent any further debug activity in thread */

            t->debug_active = false;

            t->cur_event = 0;   /* none */

            /* Still has go? */

            if (t->debug_stop == false) {

                /*

                * Yes, so clear go. As debug_active == false,

                 * this doesn't affect anything.

                 */

                t->debug_stop = true;  

                /* Answer GO call */

                klog_printf("answer GO call with EVENT_FINISHED");

                IPC_SET_RETVAL(t->debug_go_call->data, 0);

                IPC_SET_ARG1(t->debug_go_call->data, UDEBUG_EVENT_FINISHED);

                /* FIXME: must not call with interrupts disabled!!*/

                ipc_answer(&ta->answerbox, t->debug_go_call);

                t->debug_go_call = NULL;

            } else {

                /*

                 * Debug_stop is already at initial value.

                 * Yet this means the thread needs waking up.

                 */

                /*

                 * t's lock must not be held when calling

                 * waitq_wakeup.

                 */

                waitq_wakeup(&t->go_wq, WAKEUP_FIRST);

            }

        }

        spinlock_unlock(&t->debug_lock);

        interrupts_restore(ipl);

    }

    ta->udebug.dt_state = UDEBUG_TS_INACTIVE;

    ta->udebug.debugger = NULL;

    return 0;

}

/** @}

 */