source: mainline/kernel/generic/src/ipc/sysipc.c@ 228e490

/*
 * 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 <ipc/kbox.h>
#include <synch/waitq.h>
#include <udebug/udebug_ipc.h>
#include <arch/interrupt.h>
#include <syscall/copy.h>
#include <security/cap.h>
#include <console/console.h>
#include <mm/as.h>
#include <print.h>

/**
 * Maximum buffer size allowed for IPC_M_DATA_WRITE and IPC_M_DATA_READ
 * requests.
 */
#define DATA_XFER_LIMIT  (64 * 1024)

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

/** Get phone from the current task by ID.
 *
 * @param phoneid Phone ID.
 * @param phone   Place to store pointer to phone.
 *
 * @return EOK on success, EINVAL if ID is invalid.
 *
 */
static int phone_get(sysarg_t phoneid, phone_t **phone)
{
        if (phoneid >= IPC_MAX_PHONES)
                return EINVAL;
        
        *phone = &TASK->phones[phoneid];
        return EOK;
}

/** Decide if the interface and method is a system method.
 *
 * @param imethod Interface and method to be decided.
 *
 * @return True if the interface and method is a system
 *         interface and method.
 *
 */
static inline bool method_is_system(sysarg_t imethod)
{
        if (imethod <= IPC_M_LAST_SYSTEM)
                return true;
        
        return false;
}

/** Decide if the message with this interface and method is forwardable.
 *
 * Some system messages may be forwarded, for some of them
 * it is useless.
 *
 * @param imethod Interface and method to be decided.
 *
 * @return True if the interface and method is forwardable.
 *
 */
static inline bool method_is_forwardable(sysarg_t imethod)
{
        switch (imethod) {
        case IPC_M_CONNECTION_CLONE:
        case IPC_M_CONNECT_ME:
        case IPC_M_PHONE_HUNGUP:
                /* This message is meant only for the original recipient. */
                return false;
        default:
                return true;
        }
}

/** Decide if the message with this interface and method is immutable on forward.
 *
 * Some system messages may be forwarded but their content cannot be altered.
 *
 * @param imethod Interface and method to be decided.
 *
 * @return True if the interface and method is immutable on forward.
 *
 */
static inline bool method_is_immutable(sysarg_t imethod)
{
        switch (imethod) {
        case IPC_M_SHARE_OUT:
        case IPC_M_SHARE_IN:
        case IPC_M_DATA_WRITE:
        case IPC_M_DATA_READ:
                return true;
        default:
                return false;
        }
}


/***********************************************************************
 * 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 true if the old call contents should be saved.
 *
 */
static inline bool answer_need_old(call_t *call)
{
        switch (IPC_GET_IMETHOD(call->data)) {
        case IPC_M_CONNECTION_CLONE:
        case IPC_M_CONNECT_ME:
        case IPC_M_CONNECT_TO_ME:
        case IPC_M_CONNECT_ME_TO:
        case IPC_M_SHARE_OUT:
        case IPC_M_SHARE_IN:
        case IPC_M_DATA_WRITE:
        case IPC_M_DATA_READ:
                return true;
        default:
                return false;
        }
}

/** 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)
{
        if ((native_t) IPC_GET_RETVAL(answer->data) == EHANGUP) {
                /* In case of forward, hangup the forwared phone,
                 * not the originator
                 */
                mutex_lock(&answer->data.phone->lock);
                irq_spinlock_lock(&TASK->answerbox.lock, true);
                if (answer->data.phone->state == IPC_PHONE_CONNECTED) {
                        list_remove(&answer->data.phone->link);
                        answer->data.phone->state = IPC_PHONE_SLAMMED;
                }
                irq_spinlock_unlock(&TASK->answerbox.lock, true);
                mutex_unlock(&answer->data.phone->lock);
        }
        
        if (!olddata)
                return 0;
        
        if (IPC_GET_IMETHOD(*olddata) == IPC_M_CONNECTION_CLONE) {
                int phoneid = IPC_GET_ARG1(*olddata);
                phone_t *phone = &TASK->phones[phoneid];
                
                if (IPC_GET_RETVAL(answer->data) != EOK) {
                        /*
                         * The recipient of the cloned phone rejected the offer.
                         * In this case, the connection was established at the
                         * request time and therefore we need to slam the phone.
                         * We don't merely hangup as that would result in
                         * sending IPC_M_HUNGUP to the third party on the
                         * other side of the cloned phone.
                         */
                        mutex_lock(&phone->lock);
                        if (phone->state == IPC_PHONE_CONNECTED) {
                                irq_spinlock_lock(&phone->callee->lock, true);
                                list_remove(&phone->link);
                                phone->state = IPC_PHONE_SLAMMED;
                                irq_spinlock_unlock(&phone->callee->lock, true);
                        }
                        mutex_unlock(&phone->lock);
                }
        } else if (IPC_GET_IMETHOD(*olddata) == IPC_M_CONNECT_ME) {
                phone_t *phone = (phone_t *) IPC_GET_ARG5(*olddata);
                
                if (IPC_GET_RETVAL(answer->data) != EOK) {
                        /*
                         * The other party on the cloned phoned rejected our
                         * request for connection on the protocol level.
                         * We need to break the connection without sending
                         * IPC_M_HUNGUP back.
                         */
                        mutex_lock(&phone->lock);
                        if (phone->state == IPC_PHONE_CONNECTED) {
                                irq_spinlock_lock(&phone->callee->lock, true);
                                list_remove(&phone->link);
                                phone->state = IPC_PHONE_SLAMMED;
                                irq_spinlock_unlock(&phone->callee->lock, true);
                        }
                        mutex_unlock(&phone->lock);
                }
        } else if (IPC_GET_IMETHOD(*olddata) == IPC_M_CONNECT_TO_ME) {
                int phoneid = IPC_GET_ARG5(*olddata);
                
                if (IPC_GET_RETVAL(answer->data) != EOK) {
                        /* The connection was not accepted */
                        phone_dealloc(phoneid);
                } else {
                        /* The connection was accepted */
                        phone_connect(phoneid, &answer->sender->answerbox);
                        /* Set 'phone hash' as arg5 of response */
                        IPC_SET_ARG5(answer->data,
                            (sysarg_t) &TASK->phones[phoneid]);
                }
        } else if (IPC_GET_IMETHOD(*olddata) == IPC_M_CONNECT_ME_TO) {
                /* If the users accepted call, connect */
                if (IPC_GET_RETVAL(answer->data) == EOK) {
                        ipc_phone_connect((phone_t *) IPC_GET_ARG5(*olddata),
                            &TASK->answerbox);
                }
        } else if (IPC_GET_IMETHOD(*olddata) == IPC_M_SHARE_OUT) {
                if (!IPC_GET_RETVAL(answer->data)) {
                        /* Accepted, handle as_area receipt */
                        
                        irq_spinlock_lock(&answer->sender->lock, true);
                        as_t *as = answer->sender->as;
                        irq_spinlock_unlock(&answer->sender->lock, true);
                        
                        int 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_IMETHOD(*olddata) == IPC_M_SHARE_IN) {
                if (!IPC_GET_RETVAL(answer->data)) { 
                        irq_spinlock_lock(&answer->sender->lock, true);
                        as_t *as = answer->sender->as;
                        irq_spinlock_unlock(&answer->sender->lock, true);
                        
                        int 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_IMETHOD(*olddata) == IPC_M_DATA_READ) {
                ASSERT(!answer->buffer);
                if (!IPC_GET_RETVAL(answer->data)) {
                        /* The recipient agreed to send data. */
                        uintptr_t src = IPC_GET_ARG1(answer->data);
                        uintptr_t dst = IPC_GET_ARG1(*olddata);
                        size_t max_size = IPC_GET_ARG2(*olddata);
                        size_t size = IPC_GET_ARG2(answer->data);
                        if (size && size <= max_size) {
                                /*
                                 * Copy the destination VA so that this piece of
                                 * information is not lost.
                                 */
                                IPC_SET_ARG1(answer->data, dst);
                                
                                answer->buffer = malloc(size, 0);
                                int rc = copy_from_uspace(answer->buffer,
                                    (void *) src, size);
                                if (rc) {
                                        IPC_SET_RETVAL(answer->data, rc);
                                        free(answer->buffer);
                                        answer->buffer = NULL;
                                }
                        } else if (!size) {
                                IPC_SET_RETVAL(answer->data, EOK);
                        } else {
                                IPC_SET_RETVAL(answer->data, ELIMIT);
                        }
                }
        } else if (IPC_GET_IMETHOD(*olddata) == IPC_M_DATA_WRITE) {
                ASSERT(answer->buffer);
                if (!IPC_GET_RETVAL(answer->data)) {
                        /* The recipient agreed to receive data. */
                        uintptr_t dst = (uintptr_t)IPC_GET_ARG1(answer->data);
                        size_t size = (size_t)IPC_GET_ARG2(answer->data);
                        size_t max_size = (size_t)IPC_GET_ARG2(*olddata);
                        
                        if (size <= max_size) {
                                int rc = copy_to_uspace((void *) dst,
                                    answer->buffer, size);
                                if (rc)
                                        IPC_SET_RETVAL(answer->data, rc);
                        } else {
                                IPC_SET_RETVAL(answer->data, ELIMIT);
                        }
                }
                free(answer->buffer);
                answer->buffer = NULL;
        }
        
        return 0;
}

static void phones_lock(phone_t *p1, phone_t *p2)
{
        if (p1 < p2) {
                mutex_lock(&p1->lock);
                mutex_lock(&p2->lock);
        } else if (p1 > p2) {
                mutex_lock(&p2->lock);
                mutex_lock(&p1->lock);
        } else
                mutex_lock(&p1->lock);
}

static void phones_unlock(phone_t *p1, phone_t *p2)
{
        mutex_unlock(&p1->lock);
        if (p1 != p2)
                mutex_unlock(&p2->lock);
}

/** Called before the request is sent.
 *
 * @param call  Call structure with the request.
 * @param phone Phone that the call will be sent through.
 *
 * @return Return 0 on success, ELIMIT or EPERM on error.
 *
 */
static int request_preprocess(call_t *call, phone_t *phone)
{
        switch (IPC_GET_IMETHOD(call->data)) {
        case IPC_M_CONNECTION_CLONE: {
                phone_t *cloned_phone;
                if (phone_get(IPC_GET_ARG1(call->data), &cloned_phone) != EOK)
                        return ENOENT;
                
                phones_lock(cloned_phone, phone);
                
                if ((cloned_phone->state != IPC_PHONE_CONNECTED) ||
                    phone->state != IPC_PHONE_CONNECTED) {
                        phones_unlock(cloned_phone, phone);
                        return EINVAL;
                }
                
                /*
                 * We can be pretty sure now that both tasks exist and we are
                 * connected to them. As we continue to hold the phone locks,
                 * we are effectively preventing them from finishing their
                 * potential cleanup.
                 *
                 */
                int newphid = phone_alloc(phone->callee->task);
                if (newphid < 0) {
                        phones_unlock(cloned_phone, phone);
                        return ELIMIT;
                }
                
                ipc_phone_connect(&phone->callee->task->phones[newphid],
                    cloned_phone->callee);
                phones_unlock(cloned_phone, phone);
                
                /* Set the new phone for the callee. */
                IPC_SET_ARG1(call->data, newphid);
                break;
        }
        case IPC_M_CONNECT_ME:
                IPC_SET_ARG5(call->data, (sysarg_t) phone);
                break;
        case IPC_M_CONNECT_ME_TO: {
                int newphid = phone_alloc(TASK);
                if (newphid < 0)
                        return ELIMIT;
                
                /* Set arg5 for server */
                IPC_SET_ARG5(call->data, (sysarg_t) &TASK->phones[newphid]);
                call->flags |= IPC_CALL_CONN_ME_TO;
                call->priv = newphid;
                break;
        }
        case IPC_M_SHARE_OUT: {
                size_t 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_READ: {
                size_t size = IPC_GET_ARG2(call->data);
                if ((size <= 0 || (size > DATA_XFER_LIMIT)))
                        return ELIMIT;
                
                break;
        }
        case IPC_M_DATA_WRITE: {
                uintptr_t src = IPC_GET_ARG1(call->data);
                size_t size = IPC_GET_ARG2(call->data);
                
                if (size > DATA_XFER_LIMIT)
                        return ELIMIT;
                
                call->buffer = (uint8_t *) malloc(size, 0);
                int rc = copy_from_uspace(call->buffer, (void *) src, size);
                if (rc != 0) {
                        free(call->buffer);
                        return rc;
                }
                
                break;
        }
#ifdef CONFIG_UDEBUG
        case IPC_M_DEBUG_ALL:
                return udebug_request_preprocess(call, phone);
#endif
        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 (((native_t) 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);
        }
        
        if (call->buffer) {
                /*
                 * This must be an affirmative answer to IPC_M_DATA_READ
                 * or IPC_M_DEBUG_ALL/UDEBUG_M_MEM_READ...
                 *
                 */
                uintptr_t dst = IPC_GET_ARG1(call->data);
                size_t size = IPC_GET_ARG2(call->data);
                int rc = copy_to_uspace((void *) dst, call->buffer, size);
                if (rc)
                        IPC_SET_RETVAL(call->data, rc);
                free(call->buffer);
                call->buffer = NULL;
        }
}

/** Do basic kernel processing of received call request.
 *
 * @param box  Destination answerbox structure.
 * @param call Call structure with the request.
 *
 * @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)
{
        if (IPC_GET_IMETHOD(call->data) == IPC_M_CONNECT_TO_ME) {
                int phoneid = phone_alloc(TASK);
                if (phoneid < 0) { /* Failed to allocate phone */
                        IPC_SET_RETVAL(call->data, ELIMIT);
                        ipc_answer(box, call);
                        return -1;
                }
                
                IPC_SET_ARG5(call->data, phoneid);
        }
        
        switch (IPC_GET_IMETHOD(call->data)) {
        case IPC_M_DEBUG_ALL:
                return -1;
        default:
                break;
        }
        
        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 imethod Interface and 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 user-space structure where the reply call will
 *                be stored.
 *
 * @return 0 on success.
 * @return ENOENT if there is no such phone handle.
 *
 */
sysarg_t sys_ipc_call_sync_fast(sysarg_t phoneid, sysarg_t imethod,
    sysarg_t arg1, sysarg_t arg2, sysarg_t arg3, ipc_data_t *data)
{
        phone_t *phone;
        if (phone_get(phoneid, &phone) != EOK)
                return ENOENT;
        
        call_t *call = ipc_call_alloc(0);
        IPC_SET_IMETHOD(call->data, imethod);
        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);
        
        int res = request_preprocess(call, phone);
        int rc;
        
        if (!res) {
#ifdef CONFIG_UDEBUG
                udebug_stoppable_begin();
#endif
                rc = ipc_call_sync(phone, call);
#ifdef CONFIG_UDEBUG
                udebug_stoppable_end();
#endif
                
                if (rc != EOK) {
                        /* The call will be freed by ipc_cleanup(). */
                        return rc;
                }
                
                process_answer(call);
        } else
                IPC_SET_RETVAL(call->data, res);
        
        rc = STRUCT_TO_USPACE(&data->args, &call->data.args);
        ipc_call_free(call);
        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 request User-space address of call data with the request.
 * @param reply   User-space address of call data where to store the
 *                answer.
 *
 * @return Zero on success or an error code.
 *
 */
sysarg_t sys_ipc_call_sync_slow(sysarg_t phoneid, ipc_data_t *request,
    ipc_data_t *reply)
{
        phone_t *phone;
        if (phone_get(phoneid, &phone) != EOK)
                return ENOENT;
        
        call_t *call = ipc_call_alloc(0);
        int rc = copy_from_uspace(&call->data.args, &request->args,
            sizeof(call->data.args));
        if (rc != 0) {
                ipc_call_free(call);
                return (sysarg_t) rc;
        }
        
        int res = request_preprocess(call, phone);
        
        if (!res) {
#ifdef CONFIG_UDEBUG
                udebug_stoppable_begin();
#endif
                rc = ipc_call_sync(phone, call);
#ifdef CONFIG_UDEBUG
                udebug_stoppable_end();
#endif
                
                if (rc != EOK) {
                        /* The call will be freed by ipc_cleanup(). */
                        return rc;
                }
                
                process_answer(call);
        } else
                IPC_SET_RETVAL(call->data, res);
        
        rc = STRUCT_TO_USPACE(&reply->args, &call->data.args);
        ipc_call_free(call);
        if (rc != 0)
                return rc;
        
        return 0;
}

/** Check that the task did not exceed the allowed limit of asynchronous calls
 * made over a phone.
 *
 * @param phone Phone to check the limit against.
 *
 * @return 0 if limit not reached or -1 if limit exceeded.
 *
 */
static int check_call_limit(phone_t *phone)
{
        if (atomic_get(&phone->active_calls) >= IPC_MAX_ASYNC_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 imethod Interface and 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 Call hash on success.
 * @return IPC_CALLRET_FATAL in case of a fatal error.
 * @return IPC_CALLRET_TEMPORARY if there are too many pending
 *         asynchronous requests; answers should be handled first.
 *
 */
sysarg_t sys_ipc_call_async_fast(sysarg_t phoneid, sysarg_t imethod,
    sysarg_t arg1, sysarg_t arg2, sysarg_t arg3, sysarg_t arg4)
{
        phone_t *phone;
        if (phone_get(phoneid, &phone) != EOK)
                return IPC_CALLRET_FATAL;
        
        if (check_call_limit(phone))
                return IPC_CALLRET_TEMPORARY;
        
        call_t *call = ipc_call_alloc(0);
        IPC_SET_IMETHOD(call->data, imethod);
        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);
        
        int res = request_preprocess(call, phone);
        
        if (!res)
                ipc_call(phone, call);
        else
                ipc_backsend_err(phone, call, res);
        
        return (sysarg_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().
 *
 */
sysarg_t sys_ipc_call_async_slow(sysarg_t phoneid, ipc_data_t *data)
{
        phone_t *phone;
        if (phone_get(phoneid, &phone) != EOK)
                return IPC_CALLRET_FATAL;

        if (check_call_limit(phone))
                return IPC_CALLRET_TEMPORARY;

        call_t *call = ipc_call_alloc(0);
        int rc = copy_from_uspace(&call->data.args, &data->args,
            sizeof(call->data.args));
        if (rc != 0) {
                ipc_call_free(call);
                return (sysarg_t) rc;
        }
        
        int res = request_preprocess(call, phone);
        
        if (!res)
                ipc_call(phone, call);
        else
                ipc_backsend_err(phone, call, res);
        
        return (sysarg_t) call;
}

/** Forward a received call to another destination
 *
 * Common code for both the fast and the slow version.
 *
 * @param callid  Hash of the call to forward.
 * @param phoneid Phone handle to use for forwarding.
 * @param imethod New interface and method to use for the forwarded call.
 * @param arg1    New value of the first argument for the forwarded call.
 * @param arg2    New value of the second argument for the forwarded call.
 * @param arg3    New value of the third argument for the forwarded call.
 * @param arg4    New value of the fourth argument for the forwarded call.
 * @param arg5    New value of the fifth argument for the forwarded call.
 * @param mode    Flags that specify mode of the forward operation.
 * @param slow    If true, arg3, arg4 and arg5 are considered. Otherwise
 *                the function considers only the fast version arguments:
 *                i.e. arg1 and arg2.
 *
 * @return 0 on succes, otherwise an error code.
 *
 * Warning: Make sure that ARG5 is not rewritten for certain system IPC
 *
 */
static sysarg_t sys_ipc_forward_common(sysarg_t callid, sysarg_t phoneid,
    sysarg_t imethod, sysarg_t arg1, sysarg_t arg2, sysarg_t arg3,
    sysarg_t arg4, sysarg_t arg5, unsigned int mode, bool slow)
{
        call_t *call = get_call(callid);
        if (!call)
                return ENOENT;
        
        call->flags |= IPC_CALL_FORWARDED;
        
        phone_t *phone;
        if (phone_get(phoneid, &phone) != EOK) {
                IPC_SET_RETVAL(call->data, EFORWARD);
                ipc_answer(&TASK->answerbox, call);
                return ENOENT;
        }
        
        if (!method_is_forwardable(IPC_GET_IMETHOD(call->data))) {
                IPC_SET_RETVAL(call->data, EFORWARD);
                ipc_answer(&TASK->answerbox, call);
                return EPERM;
        }
        
        /*
         * Userspace is not allowed to change interface and method of system
         * methods on forward, allow changing ARG1, ARG2, ARG3 and ARG4 by
         * means of method, arg1, arg2 and arg3.
         * If the interface and method is immutable, don't change anything.
         */
        if (!method_is_immutable(IPC_GET_IMETHOD(call->data))) {
                if (method_is_system(IPC_GET_IMETHOD(call->data))) {
                        if (IPC_GET_IMETHOD(call->data) == IPC_M_CONNECT_TO_ME)
                                phone_dealloc(IPC_GET_ARG5(call->data));
                        
                        IPC_SET_ARG1(call->data, imethod);
                        IPC_SET_ARG2(call->data, arg1);
                        IPC_SET_ARG3(call->data, arg2);
                        
                        if (slow) {
                                IPC_SET_ARG4(call->data, arg3);
                                /*
                                 * For system methods we deliberately don't
                                 * overwrite ARG5.
                                 */
                        }
                } else {
                        IPC_SET_IMETHOD(call->data, imethod);
                        IPC_SET_ARG1(call->data, arg1);
                        IPC_SET_ARG2(call->data, arg2);
                        if (slow) {
                                IPC_SET_ARG3(call->data, arg3);
                                IPC_SET_ARG4(call->data, arg4);
                                IPC_SET_ARG5(call->data, arg5);
                        }
                }
        }
        
        return ipc_forward(call, phone, &TASK->answerbox, mode);
}

/** Forward a received call to another destination - fast version.
 *
 * In case the original interface and method is a system method, ARG1, ARG2
 * and ARG3 are overwritten in the forwarded message with the new method and
 * the new arg1 and arg2, respectively. Otherwise the IMETHOD, ARG1 and ARG2
 * are rewritten with the new interface and method, arg1 and arg2, respectively.
 * Also note there is a set of immutable methods, for which the new method and
 * arguments are not set and these values are ignored.
 *
 * @param callid  Hash of the call to forward.
 * @param phoneid Phone handle to use for forwarding.
 * @param imethod New interface and method to use for the forwarded call.
 * @param arg1    New value of the first argument for the forwarded call.
 * @param arg2    New value of the second argument for the forwarded call.
 * @param mode    Flags that specify mode of the forward operation.
 *
 * @return 0 on succes, otherwise an error code.
 *
 */
sysarg_t sys_ipc_forward_fast(sysarg_t callid, sysarg_t phoneid,
    sysarg_t imethod, sysarg_t arg1, sysarg_t arg2, unsigned int mode)
{
        return sys_ipc_forward_common(callid, phoneid, imethod, arg1, arg2, 0, 0,
            0, mode, false); 
}

/** Forward a received call to another destination - slow version.
 *
 * This function is the slow verision of the sys_ipc_forward_fast interface.
 * It can copy all five new arguments and the new interface and method from
 * the userspace. It naturally extends the functionality of the fast version.
 * For system methods, it additionally stores the new value of arg3 to ARG4.
 * For non-system methods, it additionally stores the new value of arg3, arg4
 * and arg5, respectively, to ARG3, ARG4 and ARG5, respectively.
 *
 * @param callid  Hash of the call to forward.
 * @param phoneid Phone handle to use for forwarding.
 * @param data    Userspace address of the new IPC data.
 * @param mode    Flags that specify mode of the forward operation.
 *
 * @return 0 on succes, otherwise an error code.
 *
 */
sysarg_t sys_ipc_forward_slow(sysarg_t callid, sysarg_t phoneid,
    ipc_data_t *data, unsigned int mode)
{
        ipc_data_t newdata;
        int rc = copy_from_uspace(&newdata.args, &data->args,
            sizeof(newdata.args));
        if (rc != 0)
                return (sysarg_t) rc;
        
        return sys_ipc_forward_common(callid, phoneid,
            IPC_GET_IMETHOD(newdata), IPC_GET_ARG1(newdata),
            IPC_GET_ARG2(newdata), IPC_GET_ARG3(newdata),
            IPC_GET_ARG4(newdata), IPC_GET_ARG5(newdata), mode, true); 
}

/** 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 0 on success, otherwise an error code.
 *
 */
sysarg_t sys_ipc_answer_fast(sysarg_t callid, sysarg_t retval,
    sysarg_t arg1, sysarg_t arg2, sysarg_t arg3, sysarg_t arg4)
{
        /* Do not answer notification callids */
        if (callid & IPC_CALLID_NOTIFICATION)
                return 0;
        
        call_t *call = get_call(callid);
        if (!call)
                return ENOENT;
        
        ipc_data_t saved_data;
        bool saved;
        
        if (answer_need_old(call)) {
                memcpy(&saved_data, &call->data, sizeof(call->data));
                saved = true;
        } else
                saved = false;
        
        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);
        int rc = answer_preprocess(call, saved ? &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 0 on success, otherwise an error code.
 *
 */
sysarg_t sys_ipc_answer_slow(sysarg_t callid, ipc_data_t *data)
{
        /* Do not answer notification callids */
        if (callid & IPC_CALLID_NOTIFICATION)
                return 0;
        
        call_t *call = get_call(callid);
        if (!call)
                return ENOENT;
        
        ipc_data_t saved_data;
        bool saved;
        
        if (answer_need_old(call)) {
                memcpy(&saved_data, &call->data, sizeof(call->data));
                saved = true;
        } else
                saved = false;
        
        int rc = copy_from_uspace(&call->data.args, &data->args, 
            sizeof(call->data.args));
        if (rc != 0)
                return rc;
        
        rc = answer_preprocess(call, saved ? &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 0 on success or an error code.
 *
 */
sysarg_t sys_ipc_hangup(sysarg_t phoneid)
{
        phone_t *phone;
        
        if (phone_get(phoneid, &phone) != EOK)
                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.
 *
 */
sysarg_t sys_ipc_wait_for_call(ipc_data_t *calldata, uint32_t usec,
    unsigned int flags)
{
        call_t *call;
        
restart:
        
#ifdef CONFIG_UDEBUG
        udebug_stoppable_begin();
#endif
        
        call = ipc_wait_for_call(&TASK->answerbox, usec,
            flags | SYNCH_FLAGS_INTERRUPTIBLE);
        
#ifdef CONFIG_UDEBUG
        udebug_stoppable_end();
#endif
        
        if (!call)
                return 0;
        
        if (call->flags & IPC_CALL_NOTIF) {
                /* 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 ((sysarg_t) call) | IPC_CALLID_NOTIFICATION;
        }
        
        if (call->flags & IPC_CALL_ANSWERED) {
                process_answer(call);
                
                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 ((sysarg_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)) {
                /*
                 * The callee will not receive this call and no one else has
                 * a chance to answer it. Reply with the EPARTY error code.
                 */
                ipc_data_t saved_data;
                bool saved;
                
                if (answer_need_old(call)) {
                        memcpy(&saved_data, &call->data, sizeof(call->data));
                        saved = true;
                } else
                        saved = false;
                
                IPC_SET_RETVAL(call->data, EPARTY);
                (void) answer_preprocess(call, saved ? &saved_data : NULL);
                ipc_answer(&TASK->answerbox, call);
                return 0;
        }
        
        return (sysarg_t) call;
}

/** Interrupt one thread from sys_ipc_wait_for_call().
 *
 */
sysarg_t sys_ipc_poke(void)
{
        waitq_unsleep(&TASK->answerbox.wq);
        return EOK;
}

/** Connect an IRQ handler to a task.
 *
 * @param inr     IRQ number.
 * @param devno   Device number.
 * @param imethod Interface and 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().
 *
 */
sysarg_t sys_ipc_register_irq(inr_t inr, devno_t devno, sysarg_t imethod,
    irq_code_t *ucode)
{
        if (!(cap_get(TASK) & CAP_IRQ_REG))
                return EPERM;
        
        return ipc_irq_register(&TASK->answerbox, inr, devno, imethod, ucode);
}

/** Disconnect an IRQ handler from a task.
 *
 * @param inr   IRQ number.
 * @param devno Device number.
 *
 * @return Zero on success or EPERM on error.
 *
 */
sysarg_t sys_ipc_unregister_irq(inr_t inr, devno_t devno)
{
        if (!(cap_get(TASK) & CAP_IRQ_REG))
                return EPERM;
        
        ipc_irq_unregister(&TASK->answerbox, inr, devno);
        
        return 0;
}

#ifdef __32_BITS__

/** Syscall connect to a task by ID (32 bits)
 *
 * @return Phone id on success, or negative error code.
 *
 */
sysarg_t sys_ipc_connect_kbox(sysarg64_t *uspace_taskid)
{
#ifdef CONFIG_UDEBUG
        sysarg64_t taskid;
        int rc = copy_from_uspace(&taskid, uspace_taskid, sizeof(sysarg64_t));
        if (rc != 0)
                return (sysarg_t) rc;
        
        return ipc_connect_kbox((task_id_t) taskid);
#else
        return (sysarg_t) ENOTSUP;
#endif
}

#endif  /* __32_BITS__ */

#ifdef __64_BITS__

/** Syscall connect to a task by ID (64 bits)
 *
 * @return Phone id on success, or negative error code.
 *
 */
sysarg_t sys_ipc_connect_kbox(sysarg_t taskid)
{
#ifdef CONFIG_UDEBUG
        return ipc_connect_kbox((task_id_t) taskid);
#else
        return (sysarg_t) ENOTSUP;
#endif
}

#endif  /* __64_BITS__ */

/** @}
 */