Subversion Repositories HelenOS

/*

 * Copyright (c) 2006 Ondrej Palkovsky

 * 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 genericipc

 * @{

 */

/** @file

 */

#include <arch.h>

#include <proc/task.h>

#include <proc/thread.h>

#include <errno.h>

#include <memstr.h>

#include <debug.h>

#include <ipc/ipc.h>

#include <ipc/sysipc.h>

#include <ipc/irq.h>

#include <ipc/ipcrsc.h>

#include <arch/interrupt.h>

#include <print.h>

#include <syscall/copy.h>

#include <security/cap.h>

#include <mm/as.h>

#include <print.h>

/** Maximum buffer size allowed for IPC_M_DATA_SEND requests. */

#define DATA_SEND_LIMIT     (64 * 1024)

#define GET_CHECK_PHONE(phone, phoneid, err) \

{ \

    if (phoneid > IPC_MAX_PHONES) { \

        err; \

    } \

    phone = &TASK->phones[phoneid]; \

}

#define STRUCT_TO_USPACE(dst, src)  copy_to_uspace(dst, src, sizeof(*(src)))

/** Decide if the method is a system method.

 *

 * @param method    Method to be decided.

 *

 * @return      Return 1 if the method is a system method.

 *          Otherwise return 0.

 */

static inline int method_is_system(unative_t method)

{

    if (method <= IPC_M_LAST_SYSTEM)

        return 1;

    return 0;

}

/** Decide if the message with this method is forwardable.

 *

 * - some system messages may be forwarded, for some of them

 *   it is useless

 *

 * @param method    Method to be decided.

 *

 * @return      Return 1 if the method is forwardable.

 *          Otherwise return 0.

 */

static inline int method_is_forwardable(unative_t method)

{

    switch (method) {

    case IPC_M_PHONE_HUNGUP:

        /* This message is meant only for the original recipient. */

        return 0;

    default:

        return 1;

    }

}

/** Decide if the message with this method is immutable on forward.

 *

 * - some system messages may be forwarded but their content cannot be altered

 *

 * @param method    Method to be decided.

 *

 * @return      Return 1 if the method is immutable on forward.

 *          Otherwise return 0.

 */

static inline int method_is_immutable(unative_t method)

{

    switch (method) {

    case IPC_M_AS_AREA_SEND:

    case IPC_M_AS_AREA_RECV:

    case IPC_M_DATA_SEND:

        return 1;

        break;

    default:

        return 0;

    }

}

/***********************************************************************

 * Functions that preprocess answer before sending it to the recepient.

 ***********************************************************************/

/** Decide if the caller (e.g. ipc_answer()) should save the old call contents

 * for answer_preprocess().

 *

 * @param call      Call structure to be decided.

 *

 * @return      Return 1 if the old call contents should be saved.

 *          Return 0 otherwise.

 */

static inline int answer_need_old(call_t *call)

{

    switch (IPC_GET_METHOD(call->data)) {

    case IPC_M_CONNECT_TO_ME:

    case IPC_M_CONNECT_ME_TO:

    case IPC_M_AS_AREA_SEND:

    case IPC_M_AS_AREA_RECV:

    case IPC_M_DATA_SEND:

        return 1;

    default:

        return 0;

    }

}

/** Interpret process answer as control information.

 *

 * This function is called directly after sys_ipc_answer().

 *

 * @param answer    Call structure with the answer.

 * @param olddata   Saved data of the request.

 *

 * @return      Return 0 on success or an error code.

 */

static inline int answer_preprocess(call_t *answer, ipc_data_t *olddata)

{

    int phoneid;

    if (IPC_GET_RETVAL(answer->data) == EHANGUP) {

        /* In case of forward, hangup the forwared phone,

         * not the originator

         */

        spinlock_lock(&answer->data.phone->lock);

        spinlock_lock(&TASK->answerbox.lock);

        if (answer->data.phone->state == IPC_PHONE_CONNECTED) {

            list_remove(&answer->data.phone->link);

            answer->data.phone->state = IPC_PHONE_SLAMMED;

        }

        spinlock_unlock(&TASK->answerbox.lock);

        spinlock_unlock(&answer->data.phone->lock);

    }

    if (!olddata)

        return 0;

    if (IPC_GET_METHOD(*olddata) == IPC_M_CONNECT_TO_ME) {

        phoneid = IPC_GET_ARG3(*olddata);

        if (IPC_GET_RETVAL(answer->data)) {

            /* The connection was not accepted */

            phone_dealloc(phoneid);

        } else {

            /* The connection was accepted */

            phone_connect(phoneid, &answer->sender->answerbox);

            /* Set 'phone hash' as arg3 of response */

            IPC_SET_ARG3(answer->data,

                (unative_t) &TASK->phones[phoneid]);

        }

    } else if (IPC_GET_METHOD(*olddata) == IPC_M_CONNECT_ME_TO) {

        /* If the users accepted call, connect */

        if (!IPC_GET_RETVAL(answer->data)) {

            ipc_phone_connect((phone_t *) IPC_GET_ARG5(*olddata),

                &TASK->answerbox);

        }

    } else if (IPC_GET_METHOD(*olddata) == IPC_M_AS_AREA_SEND) {

        if (!IPC_GET_RETVAL(answer->data)) {

            /* Accepted, handle as_area receipt */

            ipl_t ipl;

            int rc;

            as_t *as;

            ipl = interrupts_disable();

            spinlock_lock(&answer->sender->lock);

            as = answer->sender->as;

            spinlock_unlock(&answer->sender->lock);

            interrupts_restore(ipl);

            rc = as_area_share(as, IPC_GET_ARG1(*olddata),

                IPC_GET_ARG2(*olddata), AS,

                IPC_GET_ARG1(answer->data), IPC_GET_ARG3(*olddata));

            IPC_SET_RETVAL(answer->data, rc);

            return rc;

        }

    } else if (IPC_GET_METHOD(*olddata) == IPC_M_AS_AREA_RECV) {

        if (!IPC_GET_RETVAL(answer->data)) {

            ipl_t ipl;

            as_t *as;

            int rc;

            ipl = interrupts_disable();

            spinlock_lock(&answer->sender->lock);

            as = answer->sender->as;

            spinlock_unlock(&answer->sender->lock);

            interrupts_restore(ipl);

            rc = as_area_share(AS, IPC_GET_ARG1(answer->data),

                IPC_GET_ARG2(*olddata), as, IPC_GET_ARG1(*olddata),

                IPC_GET_ARG2(answer->data));

            IPC_SET_RETVAL(answer->data, rc);

        }

    } else if (IPC_GET_METHOD(*olddata) == IPC_M_DATA_SEND) {

        if (!IPC_GET_RETVAL(answer->data)) {

            int rc;

            uintptr_t dst;

            uintptr_t size;

            ASSERT(answer->buffer);

            dst = IPC_GET_ARG1(answer->data);

            size = IPC_GET_ARG3(answer->data);

            rc = copy_to_uspace((void *) dst, answer->buffer, size);

            if (rc != 0)

                IPC_SET_RETVAL(answer->data, rc);

            free(answer->buffer);

            answer->buffer = NULL;

        }

    }

    return 0;

}

/** Called before the request is sent.

 *

 * @param call      Call structure with the request.

 *

 * @return      Return 0 on success, ELIMIT or EPERM on error.

 */

static int request_preprocess(call_t *call)

{

    int newphid;

    size_t size;

    uintptr_t src;

    int rc;

    switch (IPC_GET_METHOD(call->data)) {

    case IPC_M_CONNECT_ME_TO:

        newphid = phone_alloc();

        if (newphid < 0)

            return ELIMIT;

        /* Set arg3 for server */

        IPC_SET_ARG5(call->data, (unative_t) &TASK->phones[newphid]);

        call->flags |= IPC_CALL_CONN_ME_TO;

        call->priv = newphid;

        break;

    case IPC_M_AS_AREA_SEND:

        size = as_area_get_size(IPC_GET_ARG1(call->data));

        if (!size)

            return EPERM;

        IPC_SET_ARG2(call->data, size);

        break;

    case IPC_M_DATA_SEND:

        src = IPC_GET_ARG2(call->data);

        size = IPC_GET_ARG3(call->data);

        if ((size <= 0) || (size > DATA_SEND_LIMIT))

            return ELIMIT;

        call->buffer = (uint8_t *) malloc(size, 0);

        rc = copy_from_uspace(call->buffer, (void *) src, size);

        if (rc != 0) {

            free(call->buffer);

            return rc;

        }

        break;

    default:

        break;

    }

    return 0;

}

/*******************************************************************************

 * Functions called to process received call/answer before passing it to uspace.

 *******************************************************************************/

/** Do basic kernel processing of received call answer.

 *

 * @param call      Call structure with the answer.

 */

static void process_answer(call_t *call)

{

    if (IPC_GET_RETVAL(call->data) == EHANGUP &&

        (call->flags & IPC_CALL_FORWARDED))

        IPC_SET_RETVAL(call->data, EFORWARD);

    if (call->flags & IPC_CALL_CONN_ME_TO) {

        if (IPC_GET_RETVAL(call->data))

            phone_dealloc(call->priv);

        else

            IPC_SET_ARG5(call->data, call->priv);

    }

}

/** Do basic kernel processing of received call request.

 *

 * @param box       Destination answerbox structure.

 * @param call      Call structure with the request.

 *

 * @return      Return 0 if the call should be passed to userspace.

 *          Return -1 if the call should be ignored.

 */

static int process_request(answerbox_t *box, call_t *call)

{

    int phoneid;

    if (IPC_GET_METHOD(call->data) == IPC_M_CONNECT_TO_ME) {

        phoneid = phone_alloc();

        if (phoneid < 0) { /* Failed to allocate phone */

            IPC_SET_RETVAL(call->data, ELIMIT);

            ipc_answer(box, call);

            return -1;

        }

        IPC_SET_ARG3(call->data, phoneid);

    }

    return 0;

}

/** Make a fast call over IPC, wait for reply and return to user.

 *

 * This function can handle only three arguments of payload, but is faster than

 * the generic function (i.e. sys_ipc_call_sync_slow()).

 *

 * @param phoneid   Phone handle for the call.

 * @param method    Method of the call.

 * @param arg1      Service-defined payload argument.

 * @param arg2      Service-defined payload argument.

 * @param arg3      Service-defined payload argument.

 * @param data      Address of userspace structure where the reply call will

 *          be stored.

 *

 * @return      Returns 0 on success.

 *          Return ENOENT if there is no such phone handle.

 */

unative_t sys_ipc_call_sync_fast(unative_t phoneid, unative_t method,

    unative_t arg1, unative_t arg2, unative_t arg3, ipc_data_t *data)

{

    call_t call;

    phone_t *phone;

    int res;

    int rc;

    GET_CHECK_PHONE(phone, phoneid, return ENOENT);

    ipc_call_static_init(&call);

    IPC_SET_METHOD(call.data, method);

    IPC_SET_ARG1(call.data, arg1);

    IPC_SET_ARG2(call.data, arg2);

    IPC_SET_ARG3(call.data, arg3);

    /*

     * To achieve deterministic behavior, zero out arguments that are beyond

     * the limits of the fast version.

     */

    IPC_SET_ARG4(call.data, 0);

    IPC_SET_ARG5(call.data, 0);

    if (!(res = request_preprocess(&call))) {

        ipc_call_sync(phone, &call);

        process_answer(&call);

    } else {

        IPC_SET_RETVAL(call.data, res);

    }

    rc = STRUCT_TO_USPACE(&data->args, &call.data.args);

    if (rc != 0)

        return rc;

    return 0;

}

/** Make a synchronous IPC call allowing to transmit the entire payload.

 *

 * @param phoneid   Phone handle for the call.

 * @param question  Userspace address of call data with the request.

 * @param reply     Userspace address of call data where to store the

 *          answer.

 *

 * @return      Zero on success or an error code.

 */

unative_t sys_ipc_call_sync_slow(unative_t phoneid, ipc_data_t *question,

    ipc_data_t *reply)

{

    call_t call;

    phone_t *phone;

    int res;

    int rc;

    ipc_call_static_init(&call);

    rc = copy_from_uspace(&call.data.args, &question->args,

        sizeof(call.data.args));

    if (rc != 0)

        return (unative_t) rc;

    GET_CHECK_PHONE(phone, phoneid, return ENOENT);

    if (!(res = request_preprocess(&call))) {

        ipc_call_sync(phone, &call);

        process_answer(&call);

    } else

        IPC_SET_RETVAL(call.data, res);

    rc = STRUCT_TO_USPACE(&reply->args, &call.data.args);

    if (rc != 0)

        return rc;

    return 0;

}

/** Check that the task did not exceed the allowed limit of asynchronous calls.

 *

 * @return      Return 0 if limit not reached or -1 if limit exceeded.

 */

static int check_call_limit(void)

{

    if (atomic_preinc(&TASK->active_calls) > IPC_MAX_ASYNC_CALLS) {

        atomic_dec(&TASK->active_calls);

        return -1;

    }

    return 0;

}

/** Make a fast asynchronous call over IPC.

 *

 * This function can only handle four arguments of payload, but is faster than

 * the generic function sys_ipc_call_async_slow().

 *

 * @param phoneid   Phone handle for the call.

 * @param method    Method of the call.

 * @param arg1      Service-defined payload argument.

 * @param arg2      Service-defined payload argument.

 * @param arg3      Service-defined payload argument.

 * @param arg4      Service-defined payload argument.

 *

 * @return      Return call hash on success.

 *          Return IPC_CALLRET_FATAL in case of a fatal error and

 *          IPC_CALLRET_TEMPORARY if there are too many pending

 *          asynchronous requests; answers should be handled first.

 */

unative_t sys_ipc_call_async_fast(unative_t phoneid, unative_t method,

    unative_t arg1, unative_t arg2, unative_t arg3, unative_t arg4)

{

    call_t *call;

    phone_t *phone;

    int res;

    if (check_call_limit())

        return IPC_CALLRET_TEMPORARY;

    GET_CHECK_PHONE(phone, phoneid, return IPC_CALLRET_FATAL);

    call = ipc_call_alloc(0);

    IPC_SET_METHOD(call->data, method);

    IPC_SET_ARG1(call->data, arg1);

    IPC_SET_ARG2(call->data, arg2);

    IPC_SET_ARG3(call->data, arg3);

    IPC_SET_ARG4(call->data, arg4);

    /*

     * To achieve deterministic behavior, zero out arguments that are beyond

     * the limits of the fast version.

     */

    IPC_SET_ARG5(call->data, 0);

    if (!(res = request_preprocess(call)))

        ipc_call(phone, call);

    else

        ipc_backsend_err(phone, call, res);

    return (unative_t) call;

}

/** Make an asynchronous IPC call allowing to transmit the entire payload.

 *

 * @param phoneid   Phone handle for the call.

 * @param data      Userspace address of call data with the request.

 *

 * @return      See sys_ipc_call_async_fast().

 */

unative_t sys_ipc_call_async_slow(unative_t phoneid, ipc_data_t *data)

{

    call_t *call;

    phone_t *phone;

    int res;

    int rc;

    if (check_call_limit())

        return IPC_CALLRET_TEMPORARY;

    GET_CHECK_PHONE(phone, phoneid, return IPC_CALLRET_FATAL);

    call = ipc_call_alloc(0);

    rc = copy_from_uspace(&call->data.args, &data->args,

        sizeof(call->data.args));

    if (rc != 0) {

        ipc_call_free(call);

        return (unative_t) rc;

    }

    if (!(res = request_preprocess(call)))

        ipc_call(phone, call);

    else

        ipc_backsend_err(phone, call, res);

    return (unative_t) call;

}

/** Forward a received call to another destination.

 *

 * @param callid    Hash of the call to forward.

 * @param phoneid   Phone handle to use for forwarding.

 * @param method    New method to use for the forwarded call.

 * @param arg1      New value of the first argument for the forwarded call.

 * @param mode      Flags that specify mode of the forward operation.

 *

 * @return      Return 0 on succes, otherwise return an error code.

 *

 * In case the original method is a system method, ARG1 and ARG2 are overwritten

 * in the forwarded message with the new method and the new arg1, respectively.

 * Otherwise the METHOD and ARG1 are rewritten with the new method and arg1,

 * respectively. Also note there is a set of immutable methods, for which the

 * new method and argument is not set and these values are ignored.

 *

 * Warning: When implementing support for changing additional payload

 *      arguments, make sure that ARG3 is not rewritten for certain

 *      system IPC

 */

unative_t sys_ipc_forward_fast(unative_t callid, unative_t phoneid,

    unative_t method, unative_t arg1, unative_t arg2, int mode)

{

    call_t *call;

    phone_t *phone;

    call = get_call(callid);

    if (!call)

        return ENOENT;

    call->flags |= IPC_CALL_FORWARDED;

    GET_CHECK_PHONE(phone, phoneid, {

        IPC_SET_RETVAL(call->data, EFORWARD);

        ipc_answer(&TASK->answerbox, call);

        return ENOENT;

    });    

    if (!method_is_forwardable(IPC_GET_METHOD(call->data))) {

        IPC_SET_RETVAL(call->data, EFORWARD);

        ipc_answer(&TASK->answerbox, call);

        return EPERM;

    }

    /*

     * Userspace is not allowed to change method of system methods on

     * forward, allow changing ARG1, ARG2 and ARG3 by means of method,

     * arg1 and arg2.

     * If the method is immutable, don't change anything.

     */

    if (!method_is_immutable(IPC_GET_METHOD(call->data))) {

        if (method_is_system(IPC_GET_METHOD(call->data))) {

            if (IPC_GET_METHOD(call->data) == IPC_M_CONNECT_TO_ME)

                phone_dealloc(IPC_GET_ARG5(call->data));

            IPC_SET_ARG1(call->data, method);

            IPC_SET_ARG2(call->data, arg1);

            IPC_SET_ARG3(call->data, arg2);

        } else {

            IPC_SET_METHOD(call->data, method);

            IPC_SET_ARG1(call->data, arg1);

            IPC_SET_ARG2(call->data, arg2);

        }

    }

    return ipc_forward(call, phone, &TASK->answerbox, mode);

}

/** Answer an IPC call - fast version.

 *

 * This function can handle only two return arguments of payload, but is faster

 * than the generic sys_ipc_answer().

 *

 * @param callid    Hash of the call to be answered.

 * @param retval    Return value of the answer.

 * @param arg1      Service-defined return value.

 * @param arg2      Service-defined return value.

 * @param arg3      Service-defined return value.

 * @param arg4      Service-defined return value.

 *

 * @return      Return 0 on success, otherwise return an error code.   

 */

unative_t sys_ipc_answer_fast(unative_t callid, unative_t retval,

    unative_t arg1, unative_t arg2, unative_t arg3, unative_t arg4)

{

    call_t *call;

    ipc_data_t saved_data;

    int saveddata = 0;

    int rc;

    /* Do not answer notification callids */

    if (callid & IPC_CALLID_NOTIFICATION)

        return 0;

    call = get_call(callid);

    if (!call)

        return ENOENT;

    if (answer_need_old(call)) {

        memcpy(&saved_data, &call->data, sizeof(call->data));

        saveddata = 1;

    }

    IPC_SET_RETVAL(call->data, retval);

    IPC_SET_ARG1(call->data, arg1);

    IPC_SET_ARG2(call->data, arg2);

    IPC_SET_ARG3(call->data, arg3);

    IPC_SET_ARG4(call->data, arg4);

    /*

     * To achieve deterministic behavior, zero out arguments that are beyond

     * the limits of the fast version.

     */

    IPC_SET_ARG5(call->data, 0);

    rc = answer_preprocess(call, saveddata ? &saved_data : NULL);

    ipc_answer(&TASK->answerbox, call);

    return rc;

}

/** Answer an IPC call.

 *

 * @param callid    Hash of the call to be answered.

 * @param data      Userspace address of call data with the answer.

 *

 * @return      Return 0 on success, otherwise return an error code.

 */

unative_t sys_ipc_answer_slow(unative_t callid, ipc_data_t *data)

{

    call_t *call;

    ipc_data_t saved_data;

    int saveddata = 0;

    int rc;

    /* Do not answer notification callids */

    if (callid & IPC_CALLID_NOTIFICATION)

        return 0;

    call = get_call(callid);

    if (!call)

        return ENOENT;

    if (answer_need_old(call)) {

        memcpy(&saved_data, &call->data, sizeof(call->data));

        saveddata = 1;

    }

    rc = copy_from_uspace(&call->data.args, &data->args,

        sizeof(call->data.args));

    if (rc != 0)

        return rc;

    rc = answer_preprocess(call, saveddata ? &saved_data : NULL);

    ipc_answer(&TASK->answerbox, call);

    return rc;

}

/** Hang up a phone.

 *

 * @param       Phone handle of the phone to be hung up.

 *

 * @return      Return 0 on success or an error code.

 */

unative_t sys_ipc_hangup(int phoneid)

{

    phone_t *phone;

    GET_CHECK_PHONE(phone, phoneid, return ENOENT);

    if (ipc_phone_hangup(phone))

        return -1;

    return 0;

}

/** Wait for an incoming IPC call or an answer.

 *

 * @param calldata  Pointer to buffer where the call/answer data is stored.

 * @param usec      Timeout. See waitq_sleep_timeout() for explanation.

 * @param flags     Select mode of sleep operation. See waitq_sleep_timeout()

 *          for explanation.

 *

 * @return      Hash of the call.

 *          If IPC_CALLID_NOTIFICATION bit is set in the hash, the

 *          call is a notification. IPC_CALLID_ANSWERED denotes an

 *          answer.

 */

unative_t sys_ipc_wait_for_call(ipc_data_t *calldata, uint32_t usec, int flags)

{

    call_t *call;

restart:   

    call = ipc_wait_for_call(&TASK->answerbox, usec,

        flags | SYNCH_FLAGS_INTERRUPTIBLE);

    if (!call)

        return 0;

    if (call->flags & IPC_CALL_NOTIF) {

        ASSERT(! (call->flags & IPC_CALL_STATIC_ALLOC));

        /* Set in_phone_hash to the interrupt counter */

        call->data.phone = (void *) call->priv;

        STRUCT_TO_USPACE(calldata, &call->data);

        ipc_call_free(call);

        return ((unative_t) call) | IPC_CALLID_NOTIFICATION;

    }

    if (call->flags & IPC_CALL_ANSWERED) {

        process_answer(call);

        ASSERT(! (call->flags & IPC_CALL_STATIC_ALLOC));

        atomic_dec(&TASK->active_calls);

        if (call->flags & IPC_CALL_DISCARD_ANSWER) {

            ipc_call_free(call);

            goto restart;

        }

        STRUCT_TO_USPACE(&calldata->args, &call->data.args);

        ipc_call_free(call);

        return ((unative_t) call) | IPC_CALLID_ANSWERED;

    }

    if (process_request(&TASK->answerbox, call))

        goto restart;

    /* Include phone address('id') of the caller in the request,

     * copy whole call->data, not only call->data.args */

    if (STRUCT_TO_USPACE(calldata, &call->data)) {

        return 0;

    }

    return (unative_t)call;

}

/** Connect an IRQ handler to a task.

 *

 * @param inr       IRQ number.

 * @param devno     Device number.

 * @param method    Method to be associated with the notification.

 * @param ucode     Uspace pointer to the top-half pseudocode.

 *

 * @return      EPERM or a return code returned by ipc_irq_register().

 */

unative_t sys_ipc_register_irq(inr_t inr, devno_t devno, unative_t method,

    irq_code_t *ucode)

{

    if (!(cap_get(TASK) & CAP_IRQ_REG))

        return EPERM;

    return ipc_irq_register(&TASK->answerbox, inr, devno, method, ucode);

}

/** Disconnect an IRQ handler from a task.

 *

 * @param inr       IRQ number.

 * @param devno     Device number.

 *