1 /* 2 * replay-debugging.c 3 * 4 * Copyright (c) 2010-2020 Institute for System Programming 5 * of the Russian Academy of Sciences. 6 * 7 * This work is licensed under the terms of the GNU GPL, version 2 or later. 8 * See the COPYING file in the top-level directory. 9 * 10 */ 11 12 #include "qemu/osdep.h" 13 #include "qapi/error.h" 14 #include "sysemu/replay.h" 15 #include "sysemu/runstate.h" 16 #include "replay-internal.h" 17 #include "monitor/hmp.h" 18 #include "monitor/monitor.h" 19 #include "qapi/qapi-commands-replay.h" 20 #include "qapi/qmp/qdict.h" 21 #include "qemu/timer.h" 22 #include "block/snapshot.h" 23 #include "migration/snapshot.h" 24 25 static bool replay_is_debugging; 26 static int64_t replay_last_breakpoint; 27 static int64_t replay_last_snapshot; 28 29 bool replay_running_debug(void) 30 { 31 return replay_is_debugging; 32 } 33 34 void hmp_info_replay(Monitor *mon, const QDict *qdict) 35 { 36 if (replay_mode == REPLAY_MODE_NONE) { 37 monitor_printf(mon, "Record/replay is not active\n"); 38 } else { 39 monitor_printf(mon, 40 "%s execution '%s': instruction count = %"PRId64"\n", 41 replay_mode == REPLAY_MODE_RECORD ? "Recording" : "Replaying", 42 replay_get_filename(), replay_get_current_icount()); 43 } 44 } 45 46 ReplayInfo *qmp_query_replay(Error **errp) 47 { 48 ReplayInfo *retval = g_new0(ReplayInfo, 1); 49 50 retval->mode = replay_mode; 51 if (replay_get_filename()) { 52 retval->filename = g_strdup(replay_get_filename()); 53 retval->has_filename = true; 54 } 55 retval->icount = replay_get_current_icount(); 56 return retval; 57 } 58 59 static void replay_break(uint64_t icount, QEMUTimerCB callback, void *opaque) 60 { 61 assert(replay_mode == REPLAY_MODE_PLAY); 62 assert(replay_mutex_locked()); 63 assert(replay_break_icount >= replay_get_current_icount()); 64 assert(callback); 65 66 replay_break_icount = icount; 67 68 if (replay_break_timer) { 69 timer_del(replay_break_timer); 70 } 71 replay_break_timer = timer_new_ns(QEMU_CLOCK_REALTIME, 72 callback, opaque); 73 } 74 75 static void replay_delete_break(void) 76 { 77 assert(replay_mode == REPLAY_MODE_PLAY); 78 assert(replay_mutex_locked()); 79 80 if (replay_break_timer) { 81 timer_free(replay_break_timer); 82 replay_break_timer = NULL; 83 } 84 replay_break_icount = -1ULL; 85 } 86 87 static void replay_stop_vm(void *opaque) 88 { 89 vm_stop(RUN_STATE_PAUSED); 90 replay_delete_break(); 91 } 92 93 void qmp_replay_break(int64_t icount, Error **errp) 94 { 95 if (replay_mode == REPLAY_MODE_PLAY) { 96 if (icount >= replay_get_current_icount()) { 97 replay_break(icount, replay_stop_vm, NULL); 98 } else { 99 error_setg(errp, 100 "cannot set breakpoint at the instruction in the past"); 101 } 102 } else { 103 error_setg(errp, "setting the breakpoint is allowed only in play mode"); 104 } 105 } 106 107 void hmp_replay_break(Monitor *mon, const QDict *qdict) 108 { 109 int64_t icount = qdict_get_try_int(qdict, "icount", -1LL); 110 Error *err = NULL; 111 112 qmp_replay_break(icount, &err); 113 if (err) { 114 error_report_err(err); 115 return; 116 } 117 } 118 119 void qmp_replay_delete_break(Error **errp) 120 { 121 if (replay_mode == REPLAY_MODE_PLAY) { 122 replay_delete_break(); 123 } else { 124 error_setg(errp, "replay breakpoints are allowed only in play mode"); 125 } 126 } 127 128 void hmp_replay_delete_break(Monitor *mon, const QDict *qdict) 129 { 130 Error *err = NULL; 131 132 qmp_replay_delete_break(&err); 133 if (err) { 134 error_report_err(err); 135 return; 136 } 137 } 138 139 static char *replay_find_nearest_snapshot(int64_t icount, 140 int64_t *snapshot_icount) 141 { 142 BlockDriverState *bs; 143 QEMUSnapshotInfo *sn_tab; 144 QEMUSnapshotInfo *nearest = NULL; 145 char *ret = NULL; 146 int nb_sns, i; 147 AioContext *aio_context; 148 149 *snapshot_icount = -1; 150 151 bs = bdrv_all_find_vmstate_bs(); 152 if (!bs) { 153 goto fail; 154 } 155 aio_context = bdrv_get_aio_context(bs); 156 157 aio_context_acquire(aio_context); 158 nb_sns = bdrv_snapshot_list(bs, &sn_tab); 159 aio_context_release(aio_context); 160 161 for (i = 0; i < nb_sns; i++) { 162 if (bdrv_all_find_snapshot(sn_tab[i].name, &bs) == 0) { 163 if (sn_tab[i].icount != -1ULL 164 && sn_tab[i].icount <= icount 165 && (!nearest || nearest->icount < sn_tab[i].icount)) { 166 nearest = &sn_tab[i]; 167 } 168 } 169 } 170 if (nearest) { 171 ret = g_strdup(nearest->name); 172 *snapshot_icount = nearest->icount; 173 } 174 g_free(sn_tab); 175 176 fail: 177 return ret; 178 } 179 180 static void replay_seek(int64_t icount, QEMUTimerCB callback, Error **errp) 181 { 182 char *snapshot = NULL; 183 int64_t snapshot_icount; 184 185 if (replay_mode != REPLAY_MODE_PLAY) { 186 error_setg(errp, "replay must be enabled to seek"); 187 return; 188 } 189 190 snapshot = replay_find_nearest_snapshot(icount, &snapshot_icount); 191 if (snapshot) { 192 if (icount < replay_get_current_icount() 193 || replay_get_current_icount() < snapshot_icount) { 194 vm_stop(RUN_STATE_RESTORE_VM); 195 load_snapshot(snapshot, errp); 196 } 197 g_free(snapshot); 198 } 199 if (replay_get_current_icount() <= icount) { 200 replay_break(icount, callback, NULL); 201 vm_start(); 202 } else { 203 error_setg(errp, "cannot seek to the specified instruction count"); 204 } 205 } 206 207 void qmp_replay_seek(int64_t icount, Error **errp) 208 { 209 replay_seek(icount, replay_stop_vm, errp); 210 } 211 212 void hmp_replay_seek(Monitor *mon, const QDict *qdict) 213 { 214 int64_t icount = qdict_get_try_int(qdict, "icount", -1LL); 215 Error *err = NULL; 216 217 qmp_replay_seek(icount, &err); 218 if (err) { 219 error_report_err(err); 220 return; 221 } 222 } 223 224 static void replay_stop_vm_debug(void *opaque) 225 { 226 replay_is_debugging = false; 227 vm_stop(RUN_STATE_DEBUG); 228 replay_delete_break(); 229 } 230 231 bool replay_reverse_step(void) 232 { 233 Error *err = NULL; 234 235 assert(replay_mode == REPLAY_MODE_PLAY); 236 237 if (replay_get_current_icount() != 0) { 238 replay_seek(replay_get_current_icount() - 1, 239 replay_stop_vm_debug, &err); 240 if (err) { 241 error_free(err); 242 return false; 243 } 244 replay_is_debugging = true; 245 return true; 246 } 247 248 return false; 249 } 250 251 static void replay_continue_end(void) 252 { 253 replay_is_debugging = false; 254 vm_stop(RUN_STATE_DEBUG); 255 replay_delete_break(); 256 } 257 258 static void replay_continue_stop(void *opaque) 259 { 260 Error *err = NULL; 261 if (replay_last_breakpoint != -1LL) { 262 replay_seek(replay_last_breakpoint, replay_stop_vm_debug, &err); 263 if (err) { 264 error_free(err); 265 replay_continue_end(); 266 } 267 return; 268 } 269 /* 270 * No breakpoints since the last snapshot. 271 * Find previous snapshot and try again. 272 */ 273 if (replay_last_snapshot != 0) { 274 replay_seek(replay_last_snapshot - 1, replay_continue_stop, &err); 275 if (err) { 276 error_free(err); 277 replay_continue_end(); 278 } 279 replay_last_snapshot = replay_get_current_icount(); 280 } else { 281 /* Seek to the very first step */ 282 replay_seek(0, replay_stop_vm_debug, &err); 283 if (err) { 284 error_free(err); 285 replay_continue_end(); 286 } 287 } 288 } 289 290 bool replay_reverse_continue(void) 291 { 292 Error *err = NULL; 293 294 assert(replay_mode == REPLAY_MODE_PLAY); 295 296 if (replay_get_current_icount() != 0) { 297 replay_seek(replay_get_current_icount() - 1, 298 replay_continue_stop, &err); 299 if (err) { 300 error_free(err); 301 return false; 302 } 303 replay_last_breakpoint = -1LL; 304 replay_is_debugging = true; 305 replay_last_snapshot = replay_get_current_icount(); 306 return true; 307 } 308 309 return false; 310 } 311 312 void replay_breakpoint(void) 313 { 314 assert(replay_mode == REPLAY_MODE_PLAY); 315 replay_last_breakpoint = replay_get_current_icount(); 316 } 317 318 void replay_gdb_attached(void) 319 { 320 /* 321 * Create VM snapshot on temporary overlay to allow reverse 322 * debugging even if snapshots were not enabled. 323 */ 324 if (replay_mode == REPLAY_MODE_PLAY 325 && !replay_snapshot) { 326 if (save_snapshot("start_debugging", NULL) != 0) { 327 /* Can't create the snapshot. Continue conventional debugging. */ 328 } 329 } 330 } 331