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