| 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 "system/replay.h" |
| 15 | #include "system/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 "qobject/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 | #ifdef CONFIG_HMP |
| 35 | void hmp_info_replay(MonitorHMP *hmp, const QDict *qdict) |
| 36 | { |
| 37 | if (replay_mode == REPLAY_MODE_NONE) { |
| 38 | monitor_hmp_printf(hmp, "Record/replay is not active\n"); |
| 39 | } else { |
| 40 | monitor_hmp_printf(hmp, |
| 41 | "%s execution '%s': instruction count = %"PRId64"\n", |
| 42 | replay_mode == REPLAY_MODE_RECORD ? "Recording" : "Replaying", |
| 43 | replay_get_filename(), replay_get_current_icount()); |
| 44 | } |
| 45 | } |
| 46 | #endif |
| 47 | |
| 48 | ReplayInfo *qmp_query_replay(Error **errp) |
| 49 | { |
| 50 | ReplayInfo *retval = g_new0(ReplayInfo, 1); |
| 51 | |
| 52 | retval->mode = replay_mode; |
| 53 | if (replay_get_filename()) { |
| 54 | retval->filename = g_strdup(replay_get_filename()); |
| 55 | } |
| 56 | retval->icount = replay_get_current_icount(); |
| 57 | return retval; |
| 58 | } |
| 59 | |
| 60 | static void replay_break(uint64_t icount, QEMUTimerCB callback, void *opaque) |
| 61 | { |
| 62 | assert(replay_mode == REPLAY_MODE_PLAY); |
| 63 | assert(replay_mutex_locked()); |
| 64 | assert(replay_break_icount >= replay_get_current_icount()); |
| 65 | assert(callback); |
| 66 | |
| 67 | replay_break_icount = icount; |
| 68 | |
| 69 | if (replay_break_timer) { |
| 70 | timer_del(replay_break_timer); |
| 71 | } |
| 72 | replay_break_timer = timer_new_ns(QEMU_CLOCK_REALTIME, |
| 73 | callback, opaque); |
| 74 | } |
| 75 | |
| 76 | static void replay_delete_break(void) |
| 77 | { |
| 78 | assert(replay_mode == REPLAY_MODE_PLAY); |
| 79 | assert(replay_mutex_locked()); |
| 80 | |
| 81 | if (replay_break_timer) { |
| 82 | timer_free(replay_break_timer); |
| 83 | replay_break_timer = NULL; |
| 84 | } |
| 85 | replay_break_icount = -1ULL; |
| 86 | } |
| 87 | |
| 88 | static void replay_stop_vm(void *opaque) |
| 89 | { |
| 90 | vm_stop(RUN_STATE_PAUSED); |
| 91 | replay_delete_break(); |
| 92 | } |
| 93 | |
| 94 | void qmp_replay_break(int64_t icount, Error **errp) |
| 95 | { |
| 96 | if (replay_mode == REPLAY_MODE_PLAY) { |
| 97 | if (icount >= replay_get_current_icount()) { |
| 98 | replay_break(icount, replay_stop_vm, NULL); |
| 99 | } else { |
| 100 | error_setg(errp, |
| 101 | "cannot set breakpoint at the instruction in the past"); |
| 102 | } |
| 103 | } else { |
| 104 | error_setg(errp, "setting the breakpoint is allowed only in play mode"); |
| 105 | } |
| 106 | } |
| 107 | |
| 108 | #ifdef CONFIG_HMP |
| 109 | void hmp_replay_break(MonitorHMP *hmp, const QDict *qdict) |
| 110 | { |
| 111 | int64_t icount = qdict_get_try_int(qdict, "icount", -1LL); |
| 112 | Error *err = NULL; |
| 113 | |
| 114 | qmp_replay_break(icount, &err); |
| 115 | if (err) { |
| 116 | error_report_err(err); |
| 117 | return; |
| 118 | } |
| 119 | } |
| 120 | #endif |
| 121 | |
| 122 | void qmp_replay_delete_break(Error **errp) |
| 123 | { |
| 124 | if (replay_mode == REPLAY_MODE_PLAY) { |
| 125 | replay_delete_break(); |
| 126 | } else { |
| 127 | error_setg(errp, "replay breakpoints are allowed only in play mode"); |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | #ifdef CONFIG_HMP |
| 132 | void hmp_replay_delete_break(MonitorHMP *hmp, const QDict *qdict) |
| 133 | { |
| 134 | Error *err = NULL; |
| 135 | |
| 136 | qmp_replay_delete_break(&err); |
| 137 | if (err) { |
| 138 | error_report_err(err); |
| 139 | return; |
| 140 | } |
| 141 | } |
| 142 | #endif |
| 143 | |
| 144 | static char *replay_find_nearest_snapshot(int64_t icount, |
| 145 | int64_t *snapshot_icount) |
| 146 | { |
| 147 | BlockDriverState *bs; |
| 148 | g_autofree QEMUSnapshotInfo *sn_tab = NULL; |
| 149 | QEMUSnapshotInfo *nearest = NULL; |
| 150 | int rv; |
| 151 | int nb_sns, i; |
| 152 | |
| 153 | *snapshot_icount = -1; |
| 154 | |
| 155 | bs = bdrv_all_find_vmstate_bs(NULL, false, NULL, NULL); |
| 156 | if (!bs) { |
| 157 | return NULL; |
| 158 | } |
| 159 | |
| 160 | nb_sns = bdrv_snapshot_list(bs, &sn_tab); |
| 161 | if (nb_sns < 0) { |
| 162 | return NULL; |
| 163 | } |
| 164 | |
| 165 | for (i = 0; i < nb_sns; i++) { |
| 166 | rv = bdrv_all_has_snapshot(sn_tab[i].name, false, NULL, NULL); |
| 167 | if (rv < 0) { |
| 168 | return NULL; |
| 169 | } |
| 170 | if (rv == 1) { |
| 171 | if (sn_tab[i].icount != -1ULL |
| 172 | && sn_tab[i].icount <= icount |
| 173 | && (!nearest || nearest->icount < sn_tab[i].icount)) { |
| 174 | nearest = &sn_tab[i]; |
| 175 | } |
| 176 | } |
| 177 | } |
| 178 | if (!nearest) { |
| 179 | return NULL; |
| 180 | } |
| 181 | |
| 182 | *snapshot_icount = nearest->icount; |
| 183 | return g_strdup(nearest->name); |
| 184 | } |
| 185 | |
| 186 | static void replay_seek(int64_t icount, QEMUTimerCB callback, Error **errp) |
| 187 | { |
| 188 | char *snapshot = NULL; |
| 189 | int64_t snapshot_icount; |
| 190 | |
| 191 | if (replay_mode != REPLAY_MODE_PLAY) { |
| 192 | error_setg(errp, "replay must be enabled to seek"); |
| 193 | return; |
| 194 | } |
| 195 | |
| 196 | snapshot = replay_find_nearest_snapshot(icount, &snapshot_icount); |
| 197 | if (snapshot) { |
| 198 | if (icount < replay_get_current_icount() |
| 199 | || replay_get_current_icount() < snapshot_icount) { |
| 200 | vm_stop(RUN_STATE_RESTORE_VM); |
| 201 | load_snapshot(snapshot, NULL, false, NULL, errp); |
| 202 | } |
| 203 | g_free(snapshot); |
| 204 | } |
| 205 | if (replay_get_current_icount() <= icount) { |
| 206 | replay_break(icount, callback, NULL); |
| 207 | vm_start(); |
| 208 | } else { |
| 209 | error_setg(errp, "cannot seek to the specified instruction count"); |
| 210 | } |
| 211 | } |
| 212 | |
| 213 | void qmp_replay_seek(int64_t icount, Error **errp) |
| 214 | { |
| 215 | replay_seek(icount, replay_stop_vm, errp); |
| 216 | } |
| 217 | |
| 218 | #ifdef CONFIG_HMP |
| 219 | void hmp_replay_seek(MonitorHMP *hmp, const QDict *qdict) |
| 220 | { |
| 221 | int64_t icount = qdict_get_try_int(qdict, "icount", -1LL); |
| 222 | Error *err = NULL; |
| 223 | |
| 224 | qmp_replay_seek(icount, &err); |
| 225 | if (err) { |
| 226 | error_report_err(err); |
| 227 | return; |
| 228 | } |
| 229 | } |
| 230 | #endif |
| 231 | |
| 232 | static void replay_stop_vm_debug(void *opaque) |
| 233 | { |
| 234 | replay_is_debugging = false; |
| 235 | vm_stop(RUN_STATE_DEBUG); |
| 236 | replay_delete_break(); |
| 237 | } |
| 238 | |
| 239 | bool replay_reverse_step(void) |
| 240 | { |
| 241 | Error *err = NULL; |
| 242 | |
| 243 | assert(replay_mode == REPLAY_MODE_PLAY); |
| 244 | |
| 245 | if (replay_get_current_icount() != 0) { |
| 246 | replay_seek(replay_get_current_icount() - 1, |
| 247 | replay_stop_vm_debug, &err); |
| 248 | if (err) { |
| 249 | error_free(err); |
| 250 | return false; |
| 251 | } |
| 252 | replay_is_debugging = true; |
| 253 | return true; |
| 254 | } |
| 255 | |
| 256 | return false; |
| 257 | } |
| 258 | |
| 259 | static void replay_continue_end(void) |
| 260 | { |
| 261 | replay_is_debugging = false; |
| 262 | vm_stop(RUN_STATE_DEBUG); |
| 263 | replay_delete_break(); |
| 264 | } |
| 265 | |
| 266 | static void replay_continue_stop(void *opaque) |
| 267 | { |
| 268 | Error *err = NULL; |
| 269 | if (replay_last_breakpoint != -1LL) { |
| 270 | replay_seek(replay_last_breakpoint, replay_stop_vm_debug, &err); |
| 271 | if (err) { |
| 272 | error_free(err); |
| 273 | replay_continue_end(); |
| 274 | } |
| 275 | return; |
| 276 | } |
| 277 | /* |
| 278 | * No breakpoints since the last snapshot. |
| 279 | * Find previous snapshot and try again. |
| 280 | */ |
| 281 | if (replay_last_snapshot != 0) { |
| 282 | replay_seek(replay_last_snapshot - 1, replay_continue_stop, &err); |
| 283 | if (err) { |
| 284 | error_free(err); |
| 285 | replay_continue_end(); |
| 286 | } |
| 287 | replay_last_snapshot = replay_get_current_icount(); |
| 288 | } else { |
| 289 | /* Seek to the very first step */ |
| 290 | replay_seek(0, replay_stop_vm_debug, &err); |
| 291 | if (err) { |
| 292 | error_free(err); |
| 293 | replay_continue_end(); |
| 294 | } |
| 295 | } |
| 296 | } |
| 297 | |
| 298 | bool replay_reverse_continue(void) |
| 299 | { |
| 300 | Error *err = NULL; |
| 301 | |
| 302 | assert(replay_mode == REPLAY_MODE_PLAY); |
| 303 | |
| 304 | if (replay_get_current_icount() != 0) { |
| 305 | replay_seek(replay_get_current_icount() - 1, |
| 306 | replay_continue_stop, &err); |
| 307 | if (err) { |
| 308 | error_free(err); |
| 309 | return false; |
| 310 | } |
| 311 | replay_last_breakpoint = -1LL; |
| 312 | replay_is_debugging = true; |
| 313 | replay_last_snapshot = replay_get_current_icount(); |
| 314 | return true; |
| 315 | } |
| 316 | |
| 317 | return false; |
| 318 | } |
| 319 | |
| 320 | void replay_breakpoint(void) |
| 321 | { |
| 322 | assert(replay_mode == REPLAY_MODE_PLAY); |
| 323 | replay_last_breakpoint = replay_get_current_icount(); |
| 324 | } |
| 325 | |
| 326 | void replay_gdb_attached(void) |
| 327 | { |
| 328 | /* |
| 329 | * Create VM snapshot on temporary overlay to allow reverse |
| 330 | * debugging even if snapshots were not enabled. |
| 331 | */ |
| 332 | if (replay_mode == REPLAY_MODE_PLAY |
| 333 | && !replay_snapshot) { |
| 334 | if (!save_snapshot("start_debugging", true, NULL, false, NULL, NULL)) { |
| 335 | /* Can't create the snapshot. Continue conventional debugging. */ |
| 336 | } |
| 337 | } |
| 338 | } |