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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 operations.

 */

#include <console/klog.h>

#include <proc/task.h>

#include <proc/thread.h>

#include <arch.h>

#include <errno.h>

#include <syscall/copy.h>

#include <ipc/ipc.h>

#include <udebug/udebug.h>

#include <udebug/udebug_ops.h>

/**

 * Prepare a thread for a debugging operation.

 *

 * Simply put, return thread t with t->debug_lock held,

 * but only if it verifies all conditions.

 *

 * Specifically, verifies that thread t exists, is a userspace thread,

 * and belongs to the current task (TASK). Verifies, that the thread

 * has (or hasn't) go according to having_go (typically false).

 * It also locks t->debug_lock, making sure that t->debug_active is true

 * - that the thread is in a valid debugging session.

 *

 * Returns EOK if all went well, or an error code otherwise.

 * Interrupts must be already disabled when calling this function.

 *

 * Note: This function sports complicated locking.

 */

static int _thread_op_begin(thread_t *t, bool having_go)

{

    int rc;

    task_id_t taskid;

    taskid = TASK->taskid;

    /* Must lock threads_lock to ensure continued existence of the thread */

    spinlock_lock(&threads_lock);

    if (!thread_exists(t)) {

        spinlock_unlock(&threads_lock);

        return ENOENT;

    }

    spinlock_lock(&t->debug_lock);

    spinlock_lock(&t->lock);

    /* Now verify that it's the current task */

    if (t->task != TASK) {

        /* No such thread belonging to callee */

        rc = ENOENT;

        goto error_exit;

    }

    /* Verify that 't' is a userspace thread */

    if ((t->flags & THREAD_FLAG_USPACE) == 0) {

        /* It's not, deny its existence */

        rc = ENOENT;

        goto error_exit;

    }

    if ((t->debug_active != true) || (!t->debug_stop != having_go)) {

        /* Not in debugging session or undesired GO state */

        rc = EINVAL;

        goto error_exit;

    }

    spinlock_unlock(&threads_lock);

    spinlock_unlock(&t->lock);

    /* Only t->debug_lock left */

    return EOK; /* All went well */

    /* Executed when a check on the thread fails */

error_exit:

    spinlock_unlock(&t->lock);

    spinlock_unlock(&t->debug_lock);

    spinlock_unlock(&threads_lock);

    /* No locks left here */

    return rc;  /* Some errors occured */

}

static void _thread_op_end(thread_t *t)

{

    spinlock_unlock(&t->debug_lock);

}

/**

 * \return 0 (ok, but not done yet), 1 (done) or negative error code.

 */

int udebug_begin(call_t *call)

{

    ipl_t ipl;

    int reply;

    thread_t *t;

    link_t *cur;

    klog_printf("udebug_begin()");

    ipl = interrupts_disable();

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

    spinlock_lock(&TASK->lock);

    if (TASK->dt_state != UDEBUG_TS_INACTIVE) {

        spinlock_unlock(&TASK->lock);

        interrupts_restore(ipl);

        klog_printf("udebug_begin(): busy error");

        return EBUSY;

    }

    TASK->dt_state = UDEBUG_TS_BEGINNING;

    TASK->debug_begin_call = call;

    TASK->debugger = call->sender;

    if (TASK->not_stoppable_count == 0) {

        TASK->dt_state = UDEBUG_TS_ACTIVE;

        TASK->debug_begin_call = NULL;

        reply = 1; /* immediate reply */

    } else {

        reply = 0; /* no reply */

    }

    /* Set debug_active on all of the task's userspace threads */

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

        t = list_get_instance(cur, thread_t, th_link);

        spinlock_lock(&t->debug_lock);

        if ((t->flags & THREAD_FLAG_USPACE) != 0)

            t->debug_active = true;

        spinlock_unlock(&t->debug_lock);

    }

    spinlock_unlock(&TASK->lock);

    interrupts_restore(ipl);

    klog_printf("udebug_begin() done (%s)",

        reply ? "reply" : "stoppability wait");

    return reply;

}

int udebug_end(void)

{

    ipl_t ipl;

    int rc;

    klog_printf("udebug_end()");

    ipl = interrupts_disable();

    spinlock_lock(&TASK->lock);

    rc = udebug_task_cleanup(TASK);

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

    spinlock_unlock(&TASK->lock);

    interrupts_restore(ipl);

    if (rc < 0) return EINVAL;

    return 0;

}

int udebug_go(thread_t *t, call_t *call)

{

    ipl_t ipl;

    int rc;

    klog_printf("udebug_go()");

    ipl = interrupts_disable();

    /* On success, this will lock t->debug_lock */

    rc = _thread_op_begin(t, false);

    if (rc != EOK) {

        interrupts_restore(ipl);

        return rc;

    }

    t->debug_go_call = call;

    t->debug_stop = false;

    t->cur_event = 0;   /* none */

    /*

     * Neither t's lock nor threads_lock may be held during wakeup

     */

    waitq_wakeup(&t->go_wq, WAKEUP_FIRST);

    _thread_op_end(t);

    interrupts_restore(ipl);

    return 0;

}

int udebug_stop(thread_t *t, call_t *call)

{

    ipl_t ipl;

    int rc;

    klog_printf("udebug_stop()");

    ipl = interrupts_disable();

    /*

     * On success, this will lock t->debug_lock. Note that this makes sure

     * the thread is not stopped.

     */

    rc = _thread_op_begin(t, true);

    if (rc != EOK) {

        interrupts_restore(ipl);

        return rc;

    }

    /* Take GO away from the thread */

    t->debug_stop = true;

    if (!t->debug_stoppable) {

        /* Answer will be sent when the thread becomes stoppable */

        _thread_op_end(t);

        interrupts_restore(ipl);

        return 0;

    }

    /*

     * Answer GO call

     */

    klog_printf("udebug_stop - answering go call");

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

    call = t->debug_go_call;

    t->debug_go_call = NULL;

    IPC_SET_RETVAL(call->data, 0);

    IPC_SET_ARG1(call->data, UDEBUG_EVENT_STOP);

    klog_printf("udebug_stop/ipc_answer");

    THREAD->cur_event = UDEBUG_EVENT_STOP;

    _thread_op_end(t);

    spinlock_lock(&TASK->lock);

    ipc_answer(&TASK->answerbox, call);

    spinlock_unlock(&TASK->lock);

    interrupts_restore(ipl);

    klog_printf("udebog_stop/done");

    return 0;

}

int udebug_thread_read(void **buffer, size_t buf_size, size_t *n)

{

    thread_t *t;

    link_t *cur;

    unative_t tid;

    unsigned copied_ids;

    ipl_t ipl;

    unative_t *id_buffer;

    int flags;

    size_t max_ids;

    klog_printf("udebug_thread_read()");

    /* Allocate a buffer to hold thread IDs */

    id_buffer = malloc(buf_size, 0);

    if (!id_buffer) return ENOMEM;

    ipl = interrupts_disable();

    spinlock_lock(&TASK->lock);

    /* Verify task state */

    if (TASK->dt_state != UDEBUG_TS_ACTIVE) {

        spinlock_unlock(&TASK->lock);

        interrupts_restore(ipl);

        return EINVAL;

    }

    /* Copy down the thread IDs */

    max_ids = buf_size / sizeof(unative_t);

    copied_ids = 0;

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

        /* Do not write past end of buffer */

        if (copied_ids >= max_ids) break;

        t = list_get_instance(cur, thread_t, th_link);

        spinlock_lock(&t->lock);

        flags = t->flags;

        spinlock_unlock(&t->lock);

        /* Not interested in kernel threads */

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

            /* Using thread struct pointer as identification hash */

            tid = (unative_t) t;

            id_buffer[copied_ids++] = tid;

        }

    }

    spinlock_unlock(&TASK->lock);

    interrupts_restore(ipl);

    *buffer = id_buffer;

    *n = copied_ids * sizeof(unative_t);

    return 0;

}

int udebug_args_read(thread_t *t, void **buffer)

{

    int rc;

    ipl_t ipl;

    unative_t *arg_buffer;

    klog_printf("udebug_args_read()");

    /* Prepare a buffer to hold the arguments */

    arg_buffer = malloc(6 * sizeof(unative_t), 0);

    if (!arg_buffer) return ENOMEM;

    ipl = interrupts_disable();

    /* On success, this will lock t->debug_lock */

    rc = _thread_op_begin(t, false);

    if (rc != EOK) {

        interrupts_restore(ipl);

        return rc;

    }

    /* Additionally we need to verify that we are inside a syscall */

    if (t->cur_event != UDEBUG_EVENT_SYSCALL) {

        _thread_op_end(t);

        interrupts_restore(ipl);

        return EINVAL;

    }

    /* Copy to a local buffer before releasing the lock */

    memcpy(arg_buffer, t->syscall_args, 6 * sizeof(unative_t));

    _thread_op_end(t);

    interrupts_restore(ipl);

    *buffer = arg_buffer;

    return 0;

}

int udebug_regs_read(thread_t *t, void **buffer, size_t *n)

{

    istate_t *state;

    void *regs_buffer;

    int rc;

    ipl_t ipl;

    klog_printf("udebug_regs_read()");

    /* Prepare a buffer to hold the registers */

    regs_buffer = malloc(sizeof(istate_t), 0);

    if (!regs_buffer) return ENOMEM;

    ipl = interrupts_disable();

    /* On success, this will lock t->debug_lock */

    rc = _thread_op_begin(t, false);

    if (rc != EOK) {

        interrupts_restore(ipl);

        return rc;

    }

    state = t->uspace_state;

    if (state == NULL) {

        _thread_op_end(t);

        interrupts_restore(ipl);

        klog_printf("udebug_regs_read() - istate not available");

        return EBUSY;

    }

    /* Copy to the allocated buffer */

    memcpy(regs_buffer, state, sizeof(istate_t));

    _thread_op_end(t);

    interrupts_restore(ipl);

    *buffer = regs_buffer;

    *n = sizeof(istate_t);

    return 0;

}

int udebug_regs_write(thread_t *t, void *buffer)

{

    int rc;

    istate_t *state;

    ipl_t ipl;

    klog_printf("udebug_regs_write()");

    /* Try to change the thread's uspace_state */

    ipl = interrupts_disable();

    /* On success, this will lock t->debug_lock */

    rc = _thread_op_begin(t, false);

    if (rc != EOK) {

        interrupts_restore(ipl);

        return rc;

    }

    state = t->uspace_state;

    if (state == NULL) {

        _thread_op_end(t);

        interrupts_restore(ipl);

        klog_printf("udebug_regs_write() - istate not available");

        return EBUSY;

    }

    memcpy(t->uspace_state, buffer, sizeof(t->uspace_state));

    _thread_op_end(t);

    interrupts_restore(ipl);

    return 0;

}

int udebug_mem_read(unative_t uspace_addr, size_t n, void **buffer)

{

    void *data_buffer;

    int rc;

    klog_printf("udebug_mem_read()");

    data_buffer = malloc(n, 0);

    if (!data_buffer) return ENOMEM;

    klog_printf("udebug_mem_read: src=%u, size=%u", uspace_addr, n);

    /* NOTE: this is not strictly from a syscall... but that shouldn't

     * be a problem */

    rc = copy_from_uspace(data_buffer, (void *)uspace_addr, n);

    if (rc) return rc;

    *buffer = data_buffer;

    return 0;

}

int udebug_mem_write(unative_t uspace_addr, void *data, size_t n)

{

    int rc;

    udebug_task_state_t dts;

    klog_printf("udebug_mem_write()");

    /* Verify task state */

    spinlock_lock(&TASK->lock);

    dts = TASK->dt_state;

    spinlock_unlock(&TASK->lock);

    if (dts != UDEBUG_TS_ACTIVE)

        return EBUSY;

    klog_printf("dst=%u, size=%u", uspace_addr, n);

    /* NOTE: this is not strictly from a syscall... but that shouldn't

     * be a problem */

    rc = copy_to_uspace((void *)uspace_addr, data, n);

    if (rc) return rc;

    return 0;

}

/** @}

 */