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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* The communication mechanism for requesting that the driver perform work on
* behalf of the debugger. Messages are passed and processed in FIFO order,
* with no provision for high priority messages. High priority messages, such
* as debugger termination requests, should be passed using a different
* mechanism.
*
* Two FIFO queues are used for communication - one from the debugger to the
* driver, known as the driver_notify queue, and one from the driver to the
* debugger, known as the debugger_notify queue. Messages are added to one
* queue, processed by the party on the other end, and are sent back as
* acknowledgements on the other queue. All messages must be acknowledged, in
* part because the party who sent the message is the only one who can free it.
*
* Debugger-initiated work requests are usually triggered by dcmds such as
* ::load. In the case of a ::load, the debugger adds a load request to the
* driver_notify queue. The driver removes the request from the queue and
* processes it. When processing is complete, the message is turned into an
* acknowledgement, and completion status is added. The message is then added
* to the debugger_notify queue. Upon receipt, the debugger removes the
* message from the queue, notes the completion status, and frees it.
*
* The driver can itself initiate unsolicited work, such as the automatic
* loading of a dmod in response to a krtld module load notification. In this
* case, the driver loads the module and creates a work-completion message.
* This completion is identical to the one sent in the solicited load case
* above, with the exception of the acknowledgement bit, which isn't be set.
* When the debugger receives the completion message, it notes the completion
* status, and sends the message back to the driver via the driver_notify queue,
* this time with the acknowledgement bit set.
*/
#include <sys/types.h>
#include <kmdb/kmdb_asmutil.h>
#include <kmdb/kmdb_wr_impl.h>
#include <mdb/mdb_debug.h>
#include <mdb/mdb.h>
/*
* Called by the driver to pass a message to the debugger. The debugger could
* start running at any time. Nodes are added to the queue in FIFO order, but
* with links pointing in reverse order.
*/
void
kmdb_wr_debugger_notify(void *arg)
{
kmdb_wr_t *new = arg;
kmdb_wr_t *curtail;
new->wn_next = new->wn_prev = NULL;
membar_producer();
do {
if ((curtail = mdb.m_dbgwrtail) == NULL) {
/*
* The queue is empty, because tail will only be NULL if
* head is NULL too. We're the only one who can add
* to the queue, so we can blindly add our node. The
* debugger can't look at tail until head is non-NULL,
* so we set tail first.
*/
mdb.m_dbgwrtail = new;
membar_producer();
mdb.m_dbgwrhead = new;
membar_producer();
break;
}
/*
* Point the new node at the current tail. Attempt to set tail
* to point to our new node, but only as long as tail is what
* we think it is.
*/
new->wn_prev = curtail;
membar_producer();
} while (cas((uintptr_t *)&mdb.m_dbgwrtail, (uintptr_t)curtail,
(uintptr_t)new) != (uintptr_t)curtail);
}
/*
* Called by the debugger to receive messages from the driver. The driver
* has added the nodes in FIFO order, but has only set the prev pointers. We
* have to correct that before processing the nodes. This routine will not
* be preempted.
*/
int
kmdb_wr_debugger_process(int (*cb)(kmdb_wr_t *, void *), void *arg)
{
kmdb_wr_t *wn, *wnn;
int i;
if (mdb.m_dbgwrhead == NULL)
return (0); /* The queue is empty, so there's nothing to do */
/* Re-establish the next links so we can traverse in FIFO order */
mdb.m_dbgwrtail->wn_next = NULL;
for (wn = mdb.m_dbgwrtail; wn->wn_prev != NULL;
wn = wn->wn_prev)
wn->wn_prev->wn_next = wn;
/* We don't own wn after we've invoked the callback */
wn = mdb.m_dbgwrhead;
i = 0;
do {
wnn = wn->wn_next;
i += cb(wn, arg);
} while ((wn = wnn) != NULL);
mdb.m_dbgwrhead = mdb.m_dbgwrtail = NULL;
return (i);
}
/*
* Called by the debugger to check queue status.
*/
int
kmdb_wr_debugger_notify_isempty(void)
{
return (mdb.m_dbgwrhead == NULL);
}
/*
* Called by the debugger to pass a message to the driver. This routine will
* not be preempted.
*/
void
kmdb_wr_driver_notify(void *arg)
{
kmdb_wr_t *new = arg;
/*
* We restrict ourselves to manipulating the rear of the queue. We
* don't look at the head unless the tail is NULL.
*/
if (mdb.m_drvwrtail == NULL) {
new->wn_next = new->wn_prev = NULL;
mdb.m_drvwrhead = mdb.m_drvwrtail = new;
} else {
mdb.m_drvwrtail->wn_next = new;
new->wn_prev = mdb.m_drvwrtail;
new->wn_next = NULL;
mdb.m_drvwrtail = new;
}
}
/*
* Called by the driver to receive messages from the debugger. The debugger
* could start running at any time.
*
* NOTE: This routine may run *after* mdb_destroy(), and may *NOT* use any MDB
* services.
*/
int
kmdb_wr_driver_process(int (*cb)(kmdb_wr_t *, void *), void *arg)
{
kmdb_wr_t *worklist, *wn, *wnn;
int rc, rv, i;
if ((worklist = mdb.m_drvwrhead) == NULL) {
return (0); /* The queue is empty, so there's nothing to do */
}
mdb.m_drvwrhead = NULL;
/* The debugger uses tail, so enqueues still work */
membar_producer();
mdb.m_drvwrtail = NULL;
membar_producer();
/*
* The current set of messages has been removed from the queue, so
* we can process them at our leisure.
*/
wn = worklist;
rc = i = 0;
do {
wnn = wn->wn_next;
if ((rv = cb(wn, arg)) < 0)
rc = -1;
else
i += rv;
} while ((wn = wnn) != NULL);
return (rc == 0 ? i : -1);
}
/*
* Called by the debugger to check queue status
*/
int
kmdb_wr_driver_notify_isempty(void)
{
return (mdb.m_drvwrhead == NULL);
}
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