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