binutils-gdb/gdb/remote-notif.c

286 lines
7.9 KiB
C

/* Remote notification in GDB protocol
Copyright (C) 1988-2017 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* Remote async notification is sent from remote target over RSP.
Each type of notification is represented by an object of
'struct notif', which has a field 'pending_reply'. It is not
NULL when GDB receives a notification from GDBserver, but hasn't
acknowledge yet. Before GDB acknowledges the notification,
GDBserver shouldn't send notification again (see the header comments
in gdbserver/notif.c).
Notifications are processed in an almost-unified approach for both
all-stop mode and non-stop mode, except the timing to process them.
In non-stop mode, notifications are processed in
remote_async_get_pending_events_handler, while in all-stop mode,
they are processed in remote_resume. */
#include "defs.h"
#include "remote.h"
#include "remote-notif.h"
#include "observer.h"
#include "event-loop.h"
#include "target.h"
#include "inferior.h"
#include "infrun.h"
#include "gdbcmd.h"
int notif_debug = 0;
/* Supported clients of notifications. */
static struct notif_client *notifs[] =
{
&notif_client_stop,
};
gdb_static_assert (ARRAY_SIZE (notifs) == REMOTE_NOTIF_LAST);
static void do_notif_event_xfree (void *arg);
/* Parse the BUF for the expected notification NC, and send packet to
acknowledge. */
void
remote_notif_ack (struct notif_client *nc, char *buf)
{
struct notif_event *event = nc->alloc_event ();
struct cleanup *old_chain
= make_cleanup (do_notif_event_xfree, event);
if (notif_debug)
fprintf_unfiltered (gdb_stdlog, "notif: ack '%s'\n",
nc->ack_command);
nc->parse (nc, buf, event);
nc->ack (nc, buf, event);
discard_cleanups (old_chain);
}
/* Parse the BUF for the expected notification NC. */
struct notif_event *
remote_notif_parse (struct notif_client *nc, char *buf)
{
struct notif_event *event = nc->alloc_event ();
struct cleanup *old_chain
= make_cleanup (do_notif_event_xfree, event);
if (notif_debug)
fprintf_unfiltered (gdb_stdlog, "notif: parse '%s'\n", nc->name);
nc->parse (nc, buf, event);
discard_cleanups (old_chain);
return event;
}
DEFINE_QUEUE_P (notif_client_p);
/* Process notifications in STATE's notification queue one by one.
EXCEPT is not expected in the queue. */
void
remote_notif_process (struct remote_notif_state *state,
struct notif_client *except)
{
while (!QUEUE_is_empty (notif_client_p, state->notif_queue))
{
struct notif_client *nc = QUEUE_deque (notif_client_p,
state->notif_queue);
gdb_assert (nc != except);
if (nc->can_get_pending_events (nc))
remote_notif_get_pending_events (nc);
}
}
static void
remote_async_get_pending_events_handler (gdb_client_data data)
{
gdb_assert (target_is_non_stop_p ());
remote_notif_process ((struct remote_notif_state *) data, NULL);
}
/* Remote notification handler. Parse BUF, queue notification and
update STATE. */
void
handle_notification (struct remote_notif_state *state, char *buf)
{
struct notif_client *nc;
size_t i;
for (i = 0; i < ARRAY_SIZE (notifs); i++)
{
const char *name = notifs[i]->name;
if (startswith (buf, name)
&& buf[strlen (name)] == ':')
break;
}
/* We ignore notifications we don't recognize, for compatibility
with newer stubs. */
if (i == ARRAY_SIZE (notifs))
return;
nc = notifs[i];
if (state->pending_event[nc->id] != NULL)
{
/* We've already parsed the in-flight reply, but the stub for some
reason thought we didn't, possibly due to timeout on its side.
Just ignore it. */
if (notif_debug)
fprintf_unfiltered (gdb_stdlog,
"notif: ignoring resent notification\n");
}
else
{
struct notif_event *event
= remote_notif_parse (nc, buf + strlen (nc->name) + 1);
/* Be careful to only set it after parsing, since an error
may be thrown then. */
state->pending_event[nc->id] = event;
/* Notify the event loop there's a stop reply to acknowledge
and that there may be more events to fetch. */
QUEUE_enque (notif_client_p, state->notif_queue, nc);
if (target_is_non_stop_p ())
{
/* In non-stop, We mark REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN
in order to go on what we were doing and postpone
querying notification events to some point safe to do so.
See details in the function comment of
remote.c:remote_notif_get_pending_events.
In all-stop, GDB may be blocked to wait for the reply, we
shouldn't return to event loop until the expected reply
arrives. For example:
1.1) --> vCont;c
GDB expects getting stop reply 'T05 thread:2'.
1.2) <-- %Notif
<GDB marks the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN>
After step #1.2, we return to the event loop, which
notices there is a new event on the
REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and calls the
handler, which will send 'vNotif' packet.
1.3) --> vNotif
It is not safe to start a new sequence, because target
is still running and GDB is expecting the stop reply
from stub.
To solve this, whenever we parse a notification
successfully, we don't mark the
REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and let GDB blocked
there as before to get the sequence done.
2.1) --> vCont;c
GDB expects getting stop reply 'T05 thread:2'
2.2) <-- %Notif
<Don't mark the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN>
2.3) <-- T05 thread:2
These pending notifications can be processed later. */
mark_async_event_handler (state->get_pending_events_token);
}
if (notif_debug)
fprintf_unfiltered (gdb_stdlog,
"notif: Notification '%s' captured\n",
nc->name);
}
}
/* Invoke destructor of EVENT and xfree it. */
void
notif_event_xfree (struct notif_event *event)
{
if (event != NULL && event->dtr != NULL)
event->dtr (event);
xfree (event);
}
/* Cleanup wrapper. */
static void
do_notif_event_xfree (void *arg)
{
notif_event_xfree ((struct notif_event *) arg);
}
/* Return an allocated remote_notif_state. */
struct remote_notif_state *
remote_notif_state_allocate (void)
{
struct remote_notif_state *notif_state = XCNEW (struct remote_notif_state);
notif_state->notif_queue = QUEUE_alloc (notif_client_p, NULL);
/* Register async_event_handler for notification. */
notif_state->get_pending_events_token
= create_async_event_handler (remote_async_get_pending_events_handler,
notif_state);
return notif_state;
}
/* Free STATE and its fields. */
void
remote_notif_state_xfree (struct remote_notif_state *state)
{
int i;
QUEUE_free (notif_client_p, state->notif_queue);
/* Unregister async_event_handler for notification. */
if (state->get_pending_events_token != NULL)
delete_async_event_handler (&state->get_pending_events_token);
for (i = 0; i < REMOTE_NOTIF_LAST; i++)
notif_event_xfree (state->pending_event[i]);
xfree (state);
}
void
_initialize_notif (void)
{
add_setshow_boolean_cmd ("notification", no_class, &notif_debug,
_("\
Set debugging of async remote notification."), _("\
Show debugging of async remote notification."), _("\
When non-zero, debugging output about async remote notifications"
" is enabled."),
NULL,
NULL,
&setdebuglist, &showdebuglist);
}