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_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 }