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 rv;
 147     int nb_sns, i;
 148     AioContext *aio_context;
 149
 150     *snapshot_icount = -1;
 151
 152     bs = bdrv_all_find_vmstate_bs(NULL, false, NULL, NULL);
 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         rv = bdrv_all_has_snapshot(sn_tab[i].name, false, NULL, NULL);
 164         if (rv < 0)
 165             goto fail;
 166         if (rv == 1) {
 167             if (sn_tab[i].icount != -1ULL
 168                 && sn_tab[i].icount <= icount
 169                 && (!nearest || nearest->icount < sn_tab[i].icount)) {
 170                 nearest = &sn_tab[i];
 171             }
 172         }
 173     }
 174     if (nearest) {
 175         ret = g_strdup(nearest->name);
 176         *snapshot_icount = nearest->icount;
 177     }
 178     g_free(sn_tab);
 179
 180 fail:
 181     return ret;
 182 }
 183
 184 static void replay_seek(int64_t icount, QEMUTimerCB callback, Error **errp)
 185 {
 186     char *snapshot = NULL;
 187     int64_t snapshot_icount;
 188
 189     if (replay_mode != REPLAY_MODE_PLAY) {
 190         error_setg(errp, "replay must be enabled to seek");
 191         return;
 192     }
 193
 194     snapshot = replay_find_nearest_snapshot(icount, &snapshot_icount);
 195     if (snapshot) {
 196         if (icount < replay_get_current_icount()
 197             || replay_get_current_icount() < snapshot_icount) {
 198             vm_stop(RUN_STATE_RESTORE_VM);
 199             load_snapshot(snapshot, NULL, false, NULL, errp);
 200         }
 201         g_free(snapshot);
 202     }
 203     if (replay_get_current_icount() <= icount) {
 204         replay_break(icount, callback, NULL);
 205         vm_start();
 206     } else {
 207         error_setg(errp, "cannot seek to the specified instruction count");
 208     }
 209 }
 210
 211 void qmp_replay_seek(int64_t icount, Error **errp)
 212 {
 213     replay_seek(icount, replay_stop_vm, errp);
 214 }
 215
 216 void hmp_replay_seek(Monitor *mon, const QDict *qdict)
 217 {
 218     int64_t icount = qdict_get_try_int(qdict, "icount", -1LL);
 219     Error *err = NULL;
 220
 221     qmp_replay_seek(icount, &err);
 222     if (err) {
 223         error_report_err(err);
 224         return;
 225     }
 226 }
 227
 228 static void replay_stop_vm_debug(void *opaque)
 229 {
 230     replay_is_debugging = false;
 231     vm_stop(RUN_STATE_DEBUG);
 232     replay_delete_break();
 233 }
 234
 235 bool replay_reverse_step(void)
 236 {
 237     Error *err = NULL;
 238
 239     assert(replay_mode == REPLAY_MODE_PLAY);
 240
 241     if (replay_get_current_icount() != 0) {
 242         replay_seek(replay_get_current_icount() - 1,
 243                     replay_stop_vm_debug, &err);
 244         if (err) {
 245             error_free(err);
 246             return false;
 247         }
 248         replay_is_debugging = true;
 249         return true;
 250     }
 251
 252     return false;
 253 }
 254
 255 static void replay_continue_end(void)
 256 {
 257     replay_is_debugging = false;
 258     vm_stop(RUN_STATE_DEBUG);
 259     replay_delete_break();
 260 }
 261
 262 static void replay_continue_stop(void *opaque)
 263 {
 264     Error *err = NULL;
 265     if (replay_last_breakpoint != -1LL) {
 266         replay_seek(replay_last_breakpoint, replay_stop_vm_debug, &err);
 267         if (err) {
 268             error_free(err);
 269             replay_continue_end();
 270         }
 271         return;
 272     }
 273     /*
 274      * No breakpoints since the last snapshot.
 275      * Find previous snapshot and try again.
 276      */
 277     if (replay_last_snapshot != 0) {
 278         replay_seek(replay_last_snapshot - 1, replay_continue_stop, &err);
 279         if (err) {
 280             error_free(err);
 281             replay_continue_end();
 282         }
 283         replay_last_snapshot = replay_get_current_icount();
 284     } else {
 285         /* Seek to the very first step */
 286         replay_seek(0, replay_stop_vm_debug, &err);
 287         if (err) {
 288             error_free(err);
 289             replay_continue_end();
 290         }
 291     }
 292 }
 293
 294 bool replay_reverse_continue(void)
 295 {
 296     Error *err = NULL;
 297
 298     assert(replay_mode == REPLAY_MODE_PLAY);
 299
 300     if (replay_get_current_icount() != 0) {
 301         replay_seek(replay_get_current_icount() - 1,
 302                     replay_continue_stop, &err);
 303         if (err) {
 304             error_free(err);
 305             return false;
 306         }
 307         replay_last_breakpoint = -1LL;
 308         replay_is_debugging = true;
 309         replay_last_snapshot = replay_get_current_icount();
 310         return true;
 311     }
 312
 313     return false;
 314 }
 315
 316 void replay_breakpoint(void)
 317 {
 318     assert(replay_mode == REPLAY_MODE_PLAY);
 319     replay_last_breakpoint = replay_get_current_icount();
 320 }
 321
 322 void replay_gdb_attached(void)
 323 {
 324     /*
 325      * Create VM snapshot on temporary overlay to allow reverse
 326      * debugging even if snapshots were not enabled.
 327      */
 328     if (replay_mode == REPLAY_MODE_PLAY
 329         && !replay_snapshot) {
 330         if (!save_snapshot("start_debugging", true, NULL, false, NULL, NULL)) {
 331             /* Can't create the snapshot. Continue conventional debugging. */
 332         }
 333     }
 334 }