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
replay_running_debug(void)29 bool replay_running_debug(void)
30 {
31 return replay_is_debugging;
32 }
33
hmp_info_replay(Monitor * mon,const QDict * qdict)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
qmp_query_replay(Error ** errp)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
replay_break(uint64_t icount,QEMUTimerCB callback,void * opaque)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
replay_delete_break(void)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
replay_stop_vm(void * opaque)86 static void replay_stop_vm(void *opaque)
87 {
88 vm_stop(RUN_STATE_PAUSED);
89 replay_delete_break();
90 }
91
qmp_replay_break(int64_t icount,Error ** errp)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
hmp_replay_break(Monitor * mon,const QDict * qdict)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
qmp_replay_delete_break(Error ** errp)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
hmp_replay_delete_break(Monitor * mon,const QDict * qdict)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
replay_find_nearest_snapshot(int64_t icount,int64_t * snapshot_icount)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
replay_seek(int64_t icount,QEMUTimerCB callback,Error ** errp)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
qmp_replay_seek(int64_t icount,Error ** errp)206 void qmp_replay_seek(int64_t icount, Error **errp)
207 {
208 replay_seek(icount, replay_stop_vm, errp);
209 }
210
hmp_replay_seek(Monitor * mon,const QDict * qdict)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
replay_stop_vm_debug(void * opaque)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
replay_reverse_step(void)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
replay_continue_end(void)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
replay_continue_stop(void * opaque)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
replay_reverse_continue(void)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
replay_breakpoint(void)311 void replay_breakpoint(void)
312 {
313 assert(replay_mode == REPLAY_MODE_PLAY);
314 replay_last_breakpoint = replay_get_current_icount();
315 }
316
replay_gdb_attached(void)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 }
330