replay/replay-debugging.c

   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_del(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 void hmp_replay_break(Monitor *mon, const QDict *qdict)
 109 {
 110     int64_t icount = qdict_get_try_int(qdict, "icount", -1LL);
 111     Error *err = NULL;
 112
 113     qmp_replay_break(icount, &err);
 114     if (err) {
 115         error_report_err(err);
 116         return;
 117     }
 118 }
 119
 120 void qmp_replay_delete_break(Error **errp)
 121 {
 122     if (replay_mode == REPLAY_MODE_PLAY) {
 123         replay_delete_break();
 124     } else {
 125         error_setg(errp, "replay breakpoints are allowed only in play mode");
 126     }
 127 }
 128
 129 void hmp_replay_delete_break(Monitor *mon, const QDict *qdict)
 130 {
 131     Error *err = NULL;
 132
 133     qmp_replay_delete_break(&err);
 134     if (err) {
 135         error_report_err(err);
 136         return;
 137     }
 138 }
 139
 140 static char *replay_find_nearest_snapshot(int64_t icount,
 141                                           int64_t *snapshot_icount)
 142 {
 143     BlockDriverState *bs;
 144     QEMUSnapshotInfo *sn_tab;
 145     QEMUSnapshotInfo *nearest = NULL;
 146     char *ret = NULL;
 147     int nb_sns, i;
 148     AioContext *aio_context;
 149
 150     *snapshot_icount = -1;
 151
 152     bs = bdrv_all_find_vmstate_bs();
 153     if (!bs) {
 154         goto fail;
 155     }
 156     aio_context = bdrv_get_aio_context(bs);
 157
 158     aio_context_acquire(aio_context);
 159     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
 160     aio_context_release(aio_context);
 161
 162     for (i = 0; i < nb_sns; i++) {
 163         if (bdrv_all_find_snapshot(sn_tab[i].name, &bs) == 0) {
 164             if (sn_tab[i].icount != -1ULL
 165                 && sn_tab[i].icount <= icount
 166                 && (!nearest || nearest->icount < sn_tab[i].icount)) {
 167                 nearest = &sn_tab[i];
 168             }
 169         }
 170     }
 171     if (nearest) {
 172         ret = g_strdup(nearest->name);
 173         *snapshot_icount = nearest->icount;
 174     }
 175     g_free(sn_tab);
 176
 177 fail:
 178     return ret;
 179 }
 180
 181 static void replay_seek(int64_t icount, QEMUTimerCB callback, Error **errp)
 182 {
 183     char *snapshot = NULL;
 184     int64_t snapshot_icount;
 185
 186     if (replay_mode != REPLAY_MODE_PLAY) {
 187         error_setg(errp, "replay must be enabled to seek");
 188         return;
 189     }
 190
 191     snapshot = replay_find_nearest_snapshot(icount, &snapshot_icount);
 192     if (snapshot) {
 193         if (icount < replay_get_current_icount()
 194             || replay_get_current_icount() < snapshot_icount) {
 195             vm_stop(RUN_STATE_RESTORE_VM);
 196             load_snapshot(snapshot, errp);
 197         }
 198         g_free(snapshot);
 199     }
 200     if (replay_get_current_icount() <= icount) {
 201         replay_break(icount, callback, NULL);
 202         vm_start();
 203     } else {
 204         error_setg(errp, "cannot seek to the specified instruction count");
 205     }
 206 }
 207
 208 void qmp_replay_seek(int64_t icount, Error **errp)
 209 {
 210     replay_seek(icount, replay_stop_vm, errp);
 211 }
 212
 213 void hmp_replay_seek(Monitor *mon, const QDict *qdict)
 214 {
 215     int64_t icount = qdict_get_try_int(qdict, "icount", -1LL);
 216     Error *err = NULL;
 217
 218     qmp_replay_seek(icount, &err);
 219     if (err) {
 220         error_report_err(err);
 221         return;
 222     }
 223 }
 224
 225 static void replay_stop_vm_debug(void *opaque)
 226 {
 227     replay_is_debugging = false;
 228     vm_stop(RUN_STATE_DEBUG);
 229     replay_delete_break();
 230 }
 231
 232 bool replay_reverse_step(void)
 233 {
 234     Error *err = NULL;
 235
 236     assert(replay_mode == REPLAY_MODE_PLAY);
 237
 238     if (replay_get_current_icount() != 0) {
 239         replay_seek(replay_get_current_icount() - 1,
 240                     replay_stop_vm_debug, &err);
 241         if (err) {
 242             error_free(err);
 243             return false;
 244         }
 245         replay_is_debugging = true;
 246         return true;
 247     }
 248
 249     return false;
 250 }
 251
 252 static void replay_continue_end(void)
 253 {
 254     replay_is_debugging = false;
 255     vm_stop(RUN_STATE_DEBUG);
 256     replay_delete_break();
 257 }
 258
 259 static void replay_continue_stop(void *opaque)
 260 {
 261     Error *err = NULL;
 262     if (replay_last_breakpoint != -1LL) {
 263         replay_seek(replay_last_breakpoint, replay_stop_vm_debug, &err);
 264         if (err) {
 265             error_free(err);
 266             replay_continue_end();
 267         }
 268         return;
 269     }
 270     /*
 271      * No breakpoints since the last snapshot.
 272      * Find previous snapshot and try again.
 273      */
 274     if (replay_last_snapshot != 0) {
 275         replay_seek(replay_last_snapshot - 1, replay_continue_stop, &err);
 276         if (err) {
 277             error_free(err);
 278             replay_continue_end();
 279         }
 280         replay_last_snapshot = replay_get_current_icount();
 281     } else {
 282         /* Seek to the very first step */
 283         replay_seek(0, replay_stop_vm_debug, &err);
 284         if (err) {
 285             error_free(err);
 286             replay_continue_end();
 287         }
 288     }
 289 }
 290
 291 bool replay_reverse_continue(void)
 292 {
 293     Error *err = NULL;
 294
 295     assert(replay_mode == REPLAY_MODE_PLAY);
 296
 297     if (replay_get_current_icount() != 0) {
 298         replay_seek(replay_get_current_icount() - 1,
 299                     replay_continue_stop, &err);
 300         if (err) {
 301             error_free(err);
 302             return false;
 303         }
 304         replay_last_breakpoint = -1LL;
 305         replay_is_debugging = true;
 306         replay_last_snapshot = replay_get_current_icount();
 307         return true;
 308     }
 309
 310     return false;
 311 }
 312
 313 void replay_breakpoint(void)
 314 {
 315     assert(replay_mode == REPLAY_MODE_PLAY);
 316     replay_last_breakpoint = replay_get_current_icount();
 317 }
 318
 319 void replay_gdb_attached(void)
 320 {
 321     /*
 322      * Create VM snapshot on temporary overlay to allow reverse
 323      * debugging even if snapshots were not enabled.
 324      */
 325     if (replay_mode == REPLAY_MODE_PLAY
 326         && !replay_snapshot) {
 327         if (save_snapshot("start_debugging", NULL) != 0) {
 328             /* Can't create the snapshot. Continue conventional debugging. */
 329         }
 330     }
 331 }