| 1 | /* Remote notification in GDB protocol |
| 2 | |
| 3 | Copyright (C) 1988-2017 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | /* Remote async notification is sent from remote target over RSP. |
| 21 | Each type of notification is represented by an object of |
| 22 | 'struct notif', which has a field 'pending_reply'. It is not |
| 23 | NULL when GDB receives a notification from GDBserver, but hasn't |
| 24 | acknowledge yet. Before GDB acknowledges the notification, |
| 25 | GDBserver shouldn't send notification again (see the header comments |
| 26 | in gdbserver/notif.c). |
| 27 | |
| 28 | Notifications are processed in an almost-unified approach for both |
| 29 | all-stop mode and non-stop mode, except the timing to process them. |
| 30 | In non-stop mode, notifications are processed in |
| 31 | remote_async_get_pending_events_handler, while in all-stop mode, |
| 32 | they are processed in remote_resume. */ |
| 33 | |
| 34 | #include "defs.h" |
| 35 | #include "remote.h" |
| 36 | #include "remote-notif.h" |
| 37 | #include "observer.h" |
| 38 | #include "event-loop.h" |
| 39 | #include "target.h" |
| 40 | #include "inferior.h" |
| 41 | #include "infrun.h" |
| 42 | #include "gdbcmd.h" |
| 43 | |
| 44 | int notif_debug = 0; |
| 45 | |
| 46 | /* Supported clients of notifications. */ |
| 47 | |
| 48 | static struct notif_client *notifs[] = |
| 49 | { |
| 50 | ¬if_client_stop, |
| 51 | }; |
| 52 | |
| 53 | gdb_static_assert (ARRAY_SIZE (notifs) == REMOTE_NOTIF_LAST); |
| 54 | |
| 55 | static void do_notif_event_xfree (void *arg); |
| 56 | |
| 57 | /* Parse the BUF for the expected notification NC, and send packet to |
| 58 | acknowledge. */ |
| 59 | |
| 60 | void |
| 61 | remote_notif_ack (struct notif_client *nc, char *buf) |
| 62 | { |
| 63 | struct notif_event *event = nc->alloc_event (); |
| 64 | struct cleanup *old_chain |
| 65 | = make_cleanup (do_notif_event_xfree, event); |
| 66 | |
| 67 | if (notif_debug) |
| 68 | fprintf_unfiltered (gdb_stdlog, "notif: ack '%s'\n", |
| 69 | nc->ack_command); |
| 70 | |
| 71 | nc->parse (nc, buf, event); |
| 72 | nc->ack (nc, buf, event); |
| 73 | |
| 74 | discard_cleanups (old_chain); |
| 75 | } |
| 76 | |
| 77 | /* Parse the BUF for the expected notification NC. */ |
| 78 | |
| 79 | struct notif_event * |
| 80 | remote_notif_parse (struct notif_client *nc, char *buf) |
| 81 | { |
| 82 | struct notif_event *event = nc->alloc_event (); |
| 83 | struct cleanup *old_chain |
| 84 | = make_cleanup (do_notif_event_xfree, event); |
| 85 | |
| 86 | if (notif_debug) |
| 87 | fprintf_unfiltered (gdb_stdlog, "notif: parse '%s'\n", nc->name); |
| 88 | |
| 89 | nc->parse (nc, buf, event); |
| 90 | |
| 91 | discard_cleanups (old_chain); |
| 92 | return event; |
| 93 | } |
| 94 | |
| 95 | DEFINE_QUEUE_P (notif_client_p); |
| 96 | |
| 97 | /* Process notifications in STATE's notification queue one by one. |
| 98 | EXCEPT is not expected in the queue. */ |
| 99 | |
| 100 | void |
| 101 | remote_notif_process (struct remote_notif_state *state, |
| 102 | struct notif_client *except) |
| 103 | { |
| 104 | while (!QUEUE_is_empty (notif_client_p, state->notif_queue)) |
| 105 | { |
| 106 | struct notif_client *nc = QUEUE_deque (notif_client_p, |
| 107 | state->notif_queue); |
| 108 | |
| 109 | gdb_assert (nc != except); |
| 110 | |
| 111 | if (nc->can_get_pending_events (nc)) |
| 112 | remote_notif_get_pending_events (nc); |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | static void |
| 117 | remote_async_get_pending_events_handler (gdb_client_data data) |
| 118 | { |
| 119 | gdb_assert (target_is_non_stop_p ()); |
| 120 | remote_notif_process ((struct remote_notif_state *) data, NULL); |
| 121 | } |
| 122 | |
| 123 | /* Remote notification handler. Parse BUF, queue notification and |
| 124 | update STATE. */ |
| 125 | |
| 126 | void |
| 127 | handle_notification (struct remote_notif_state *state, char *buf) |
| 128 | { |
| 129 | struct notif_client *nc; |
| 130 | size_t i; |
| 131 | |
| 132 | for (i = 0; i < ARRAY_SIZE (notifs); i++) |
| 133 | { |
| 134 | const char *name = notifs[i]->name; |
| 135 | |
| 136 | if (startswith (buf, name) |
| 137 | && buf[strlen (name)] == ':') |
| 138 | break; |
| 139 | } |
| 140 | |
| 141 | /* We ignore notifications we don't recognize, for compatibility |
| 142 | with newer stubs. */ |
| 143 | if (i == ARRAY_SIZE (notifs)) |
| 144 | return; |
| 145 | |
| 146 | nc = notifs[i]; |
| 147 | |
| 148 | if (state->pending_event[nc->id] != NULL) |
| 149 | { |
| 150 | /* We've already parsed the in-flight reply, but the stub for some |
| 151 | reason thought we didn't, possibly due to timeout on its side. |
| 152 | Just ignore it. */ |
| 153 | if (notif_debug) |
| 154 | fprintf_unfiltered (gdb_stdlog, |
| 155 | "notif: ignoring resent notification\n"); |
| 156 | } |
| 157 | else |
| 158 | { |
| 159 | struct notif_event *event |
| 160 | = remote_notif_parse (nc, buf + strlen (nc->name) + 1); |
| 161 | |
| 162 | /* Be careful to only set it after parsing, since an error |
| 163 | may be thrown then. */ |
| 164 | state->pending_event[nc->id] = event; |
| 165 | |
| 166 | /* Notify the event loop there's a stop reply to acknowledge |
| 167 | and that there may be more events to fetch. */ |
| 168 | QUEUE_enque (notif_client_p, state->notif_queue, nc); |
| 169 | if (target_is_non_stop_p ()) |
| 170 | { |
| 171 | /* In non-stop, We mark REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN |
| 172 | in order to go on what we were doing and postpone |
| 173 | querying notification events to some point safe to do so. |
| 174 | See details in the function comment of |
| 175 | remote.c:remote_notif_get_pending_events. |
| 176 | |
| 177 | In all-stop, GDB may be blocked to wait for the reply, we |
| 178 | shouldn't return to event loop until the expected reply |
| 179 | arrives. For example: |
| 180 | |
| 181 | 1.1) --> vCont;c |
| 182 | GDB expects getting stop reply 'T05 thread:2'. |
| 183 | 1.2) <-- %Notif |
| 184 | <GDB marks the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN> |
| 185 | |
| 186 | After step #1.2, we return to the event loop, which |
| 187 | notices there is a new event on the |
| 188 | REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and calls the |
| 189 | handler, which will send 'vNotif' packet. |
| 190 | 1.3) --> vNotif |
| 191 | It is not safe to start a new sequence, because target |
| 192 | is still running and GDB is expecting the stop reply |
| 193 | from stub. |
| 194 | |
| 195 | To solve this, whenever we parse a notification |
| 196 | successfully, we don't mark the |
| 197 | REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN and let GDB blocked |
| 198 | there as before to get the sequence done. |
| 199 | |
| 200 | 2.1) --> vCont;c |
| 201 | GDB expects getting stop reply 'T05 thread:2' |
| 202 | 2.2) <-- %Notif |
| 203 | <Don't mark the REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN> |
| 204 | 2.3) <-- T05 thread:2 |
| 205 | |
| 206 | These pending notifications can be processed later. */ |
| 207 | mark_async_event_handler (state->get_pending_events_token); |
| 208 | } |
| 209 | |
| 210 | if (notif_debug) |
| 211 | fprintf_unfiltered (gdb_stdlog, |
| 212 | "notif: Notification '%s' captured\n", |
| 213 | nc->name); |
| 214 | } |
| 215 | } |
| 216 | |
| 217 | /* Invoke destructor of EVENT and xfree it. */ |
| 218 | |
| 219 | void |
| 220 | notif_event_xfree (struct notif_event *event) |
| 221 | { |
| 222 | if (event != NULL && event->dtr != NULL) |
| 223 | event->dtr (event); |
| 224 | |
| 225 | xfree (event); |
| 226 | } |
| 227 | |
| 228 | /* Cleanup wrapper. */ |
| 229 | |
| 230 | static void |
| 231 | do_notif_event_xfree (void *arg) |
| 232 | { |
| 233 | notif_event_xfree ((struct notif_event *) arg); |
| 234 | } |
| 235 | |
| 236 | /* Return an allocated remote_notif_state. */ |
| 237 | |
| 238 | struct remote_notif_state * |
| 239 | remote_notif_state_allocate (void) |
| 240 | { |
| 241 | struct remote_notif_state *notif_state = XCNEW (struct remote_notif_state); |
| 242 | |
| 243 | notif_state->notif_queue = QUEUE_alloc (notif_client_p, NULL); |
| 244 | |
| 245 | /* Register async_event_handler for notification. */ |
| 246 | |
| 247 | notif_state->get_pending_events_token |
| 248 | = create_async_event_handler (remote_async_get_pending_events_handler, |
| 249 | notif_state); |
| 250 | |
| 251 | return notif_state; |
| 252 | } |
| 253 | |
| 254 | /* Free STATE and its fields. */ |
| 255 | |
| 256 | void |
| 257 | remote_notif_state_xfree (struct remote_notif_state *state) |
| 258 | { |
| 259 | int i; |
| 260 | |
| 261 | QUEUE_free (notif_client_p, state->notif_queue); |
| 262 | |
| 263 | /* Unregister async_event_handler for notification. */ |
| 264 | if (state->get_pending_events_token != NULL) |
| 265 | delete_async_event_handler (&state->get_pending_events_token); |
| 266 | |
| 267 | for (i = 0; i < REMOTE_NOTIF_LAST; i++) |
| 268 | notif_event_xfree (state->pending_event[i]); |
| 269 | |
| 270 | xfree (state); |
| 271 | } |
| 272 | |
| 273 | void |
| 274 | _initialize_notif (void) |
| 275 | { |
| 276 | add_setshow_boolean_cmd ("notification", no_class, ¬if_debug, |
| 277 | _("\ |
| 278 | Set debugging of async remote notification."), _("\ |
| 279 | Show debugging of async remote notification."), _("\ |
| 280 | When non-zero, debugging output about async remote notifications" |
| 281 | " is enabled."), |
| 282 | NULL, |
| 283 | NULL, |
| 284 | &setdebuglist, &showdebuglist); |
| 285 | } |