aboutsummaryrefslogtreecommitdiff
path: root/dump.c
blob: 9210a72d614ab62f7babc557117204f6656504e8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
/*
 * QEMU dump
 *
 * Copyright Fujitsu, Corp. 2011, 2012
 *
 * Authors:
 *     Wen Congyang <wency@cn.fujitsu.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 *
 */

#include "qemu/osdep.h"
#include "qemu-common.h"
#include "elf.h"
#include "cpu.h"
#include "exec/cpu-all.h"
#include "exec/hwaddr.h"
#include "monitor/monitor.h"
#include "sysemu/kvm.h"
#include "sysemu/dump.h"
#include "sysemu/sysemu.h"
#include "sysemu/memory_mapping.h"
#include "sysemu/cpus.h"
#include "qapi/qmp/qerror.h"
#include "qmp-commands.h"

#include <zlib.h>
#ifdef CONFIG_LZO
#include <lzo/lzo1x.h>
#endif
#ifdef CONFIG_SNAPPY
#include <snappy-c.h>
#endif
#ifndef ELF_MACHINE_UNAME
#define ELF_MACHINE_UNAME "Unknown"
#endif

uint16_t cpu_to_dump16(DumpState *s, uint16_t val)
{
    if (s->dump_info.d_endian == ELFDATA2LSB) {
        val = cpu_to_le16(val);
    } else {
        val = cpu_to_be16(val);
    }

    return val;
}

uint32_t cpu_to_dump32(DumpState *s, uint32_t val)
{
    if (s->dump_info.d_endian == ELFDATA2LSB) {
        val = cpu_to_le32(val);
    } else {
        val = cpu_to_be32(val);
    }

    return val;
}

uint64_t cpu_to_dump64(DumpState *s, uint64_t val)
{
    if (s->dump_info.d_endian == ELFDATA2LSB) {
        val = cpu_to_le64(val);
    } else {
        val = cpu_to_be64(val);
    }

    return val;
}

static int dump_cleanup(DumpState *s)
{
    guest_phys_blocks_free(&s->guest_phys_blocks);
    memory_mapping_list_free(&s->list);
    close(s->fd);
    if (s->resume) {
        vm_start();
    }

    return 0;
}

static int fd_write_vmcore(const void *buf, size_t size, void *opaque)
{
    DumpState *s = opaque;
    size_t written_size;

    written_size = qemu_write_full(s->fd, buf, size);
    if (written_size != size) {
        return -1;
    }

    return 0;
}

static void write_elf64_header(DumpState *s, Error **errp)
{
    Elf64_Ehdr elf_header;
    int ret;

    memset(&elf_header, 0, sizeof(Elf64_Ehdr));
    memcpy(&elf_header, ELFMAG, SELFMAG);
    elf_header.e_ident[EI_CLASS] = ELFCLASS64;
    elf_header.e_ident[EI_DATA] = s->dump_info.d_endian;
    elf_header.e_ident[EI_VERSION] = EV_CURRENT;
    elf_header.e_type = cpu_to_dump16(s, ET_CORE);
    elf_header.e_machine = cpu_to_dump16(s, s->dump_info.d_machine);
    elf_header.e_version = cpu_to_dump32(s, EV_CURRENT);
    elf_header.e_ehsize = cpu_to_dump16(s, sizeof(elf_header));
    elf_header.e_phoff = cpu_to_dump64(s, sizeof(Elf64_Ehdr));
    elf_header.e_phentsize = cpu_to_dump16(s, sizeof(Elf64_Phdr));
    elf_header.e_phnum = cpu_to_dump16(s, s->phdr_num);
    if (s->have_section) {
        uint64_t shoff = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) * s->sh_info;

        elf_header.e_shoff = cpu_to_dump64(s, shoff);
        elf_header.e_shentsize = cpu_to_dump16(s, sizeof(Elf64_Shdr));
        elf_header.e_shnum = cpu_to_dump16(s, 1);
    }

    ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write elf header");
    }
}

static void write_elf32_header(DumpState *s, Error **errp)
{
    Elf32_Ehdr elf_header;
    int ret;

    memset(&elf_header, 0, sizeof(Elf32_Ehdr));
    memcpy(&elf_header, ELFMAG, SELFMAG);
    elf_header.e_ident[EI_CLASS] = ELFCLASS32;
    elf_header.e_ident[EI_DATA] = s->dump_info.d_endian;
    elf_header.e_ident[EI_VERSION] = EV_CURRENT;
    elf_header.e_type = cpu_to_dump16(s, ET_CORE);
    elf_header.e_machine = cpu_to_dump16(s, s->dump_info.d_machine);
    elf_header.e_version = cpu_to_dump32(s, EV_CURRENT);
    elf_header.e_ehsize = cpu_to_dump16(s, sizeof(elf_header));
    elf_header.e_phoff = cpu_to_dump32(s, sizeof(Elf32_Ehdr));
    elf_header.e_phentsize = cpu_to_dump16(s, sizeof(Elf32_Phdr));
    elf_header.e_phnum = cpu_to_dump16(s, s->phdr_num);
    if (s->have_section) {
        uint32_t shoff = sizeof(Elf32_Ehdr) + sizeof(Elf32_Phdr) * s->sh_info;

        elf_header.e_shoff = cpu_to_dump32(s, shoff);
        elf_header.e_shentsize = cpu_to_dump16(s, sizeof(Elf32_Shdr));
        elf_header.e_shnum = cpu_to_dump16(s, 1);
    }

    ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write elf header");
    }
}

static void write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
                             int phdr_index, hwaddr offset,
                             hwaddr filesz, Error **errp)
{
    Elf64_Phdr phdr;
    int ret;

    memset(&phdr, 0, sizeof(Elf64_Phdr));
    phdr.p_type = cpu_to_dump32(s, PT_LOAD);
    phdr.p_offset = cpu_to_dump64(s, offset);
    phdr.p_paddr = cpu_to_dump64(s, memory_mapping->phys_addr);
    phdr.p_filesz = cpu_to_dump64(s, filesz);
    phdr.p_memsz = cpu_to_dump64(s, memory_mapping->length);
    phdr.p_vaddr = cpu_to_dump64(s, memory_mapping->virt_addr);

    assert(memory_mapping->length >= filesz);

    ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write program header table");
    }
}

static void write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
                             int phdr_index, hwaddr offset,
                             hwaddr filesz, Error **errp)
{
    Elf32_Phdr phdr;
    int ret;

    memset(&phdr, 0, sizeof(Elf32_Phdr));
    phdr.p_type = cpu_to_dump32(s, PT_LOAD);
    phdr.p_offset = cpu_to_dump32(s, offset);
    phdr.p_paddr = cpu_to_dump32(s, memory_mapping->phys_addr);
    phdr.p_filesz = cpu_to_dump32(s, filesz);
    phdr.p_memsz = cpu_to_dump32(s, memory_mapping->length);
    phdr.p_vaddr = cpu_to_dump32(s, memory_mapping->virt_addr);

    assert(memory_mapping->length >= filesz);

    ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write program header table");
    }
}

static void write_elf64_note(DumpState *s, Error **errp)
{
    Elf64_Phdr phdr;
    hwaddr begin = s->memory_offset - s->note_size;
    int ret;

    memset(&phdr, 0, sizeof(Elf64_Phdr));
    phdr.p_type = cpu_to_dump32(s, PT_NOTE);
    phdr.p_offset = cpu_to_dump64(s, begin);
    phdr.p_paddr = 0;
    phdr.p_filesz = cpu_to_dump64(s, s->note_size);
    phdr.p_memsz = cpu_to_dump64(s, s->note_size);
    phdr.p_vaddr = 0;

    ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write program header table");
    }
}

static inline int cpu_index(CPUState *cpu)
{
    return cpu->cpu_index + 1;
}

static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
                              Error **errp)
{
    CPUState *cpu;
    int ret;
    int id;

    CPU_FOREACH(cpu) {
        id = cpu_index(cpu);
        ret = cpu_write_elf64_note(f, cpu, id, s);
        if (ret < 0) {
            error_setg(errp, "dump: failed to write elf notes");
            return;
        }
    }

    CPU_FOREACH(cpu) {
        ret = cpu_write_elf64_qemunote(f, cpu, s);
        if (ret < 0) {
            error_setg(errp, "dump: failed to write CPU status");
            return;
        }
    }
}

static void write_elf32_note(DumpState *s, Error **errp)
{
    hwaddr begin = s->memory_offset - s->note_size;
    Elf32_Phdr phdr;
    int ret;

    memset(&phdr, 0, sizeof(Elf32_Phdr));
    phdr.p_type = cpu_to_dump32(s, PT_NOTE);
    phdr.p_offset = cpu_to_dump32(s, begin);
    phdr.p_paddr = 0;
    phdr.p_filesz = cpu_to_dump32(s, s->note_size);
    phdr.p_memsz = cpu_to_dump32(s, s->note_size);
    phdr.p_vaddr = 0;

    ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write program header table");
    }
}

static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
                              Error **errp)
{
    CPUState *cpu;
    int ret;
    int id;

    CPU_FOREACH(cpu) {
        id = cpu_index(cpu);
        ret = cpu_write_elf32_note(f, cpu, id, s);
        if (ret < 0) {
            error_setg(errp, "dump: failed to write elf notes");
            return;
        }
    }

    CPU_FOREACH(cpu) {
        ret = cpu_write_elf32_qemunote(f, cpu, s);
        if (ret < 0) {
            error_setg(errp, "dump: failed to write CPU status");
            return;
        }
    }
}

static void write_elf_section(DumpState *s, int type, Error **errp)
{
    Elf32_Shdr shdr32;
    Elf64_Shdr shdr64;
    int shdr_size;
    void *shdr;
    int ret;

    if (type == 0) {
        shdr_size = sizeof(Elf32_Shdr);
        memset(&shdr32, 0, shdr_size);
        shdr32.sh_info = cpu_to_dump32(s, s->sh_info);
        shdr = &shdr32;
    } else {
        shdr_size = sizeof(Elf64_Shdr);
        memset(&shdr64, 0, shdr_size);
        shdr64.sh_info = cpu_to_dump32(s, s->sh_info);
        shdr = &shdr64;
    }

    ret = fd_write_vmcore(&shdr, shdr_size, s);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write section header table");
    }
}

static void write_data(DumpState *s, void *buf, int length, Error **errp)
{
    int ret;

    ret = fd_write_vmcore(buf, length, s);
    if (ret < 0) {
        error_setg(errp, "dump: failed to save memory");
    }
}

/* write the memory to vmcore. 1 page per I/O. */
static void write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
                         int64_t size, Error **errp)
{
    int64_t i;
    Error *local_err = NULL;

    for (i = 0; i < size / s->dump_info.page_size; i++) {
        write_data(s, block->host_addr + start + i * s->dump_info.page_size,
                   s->dump_info.page_size, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }
    }

    if ((size % s->dump_info.page_size) != 0) {
        write_data(s, block->host_addr + start + i * s->dump_info.page_size,
                   size % s->dump_info.page_size, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }
    }
}

/* get the memory's offset and size in the vmcore */
static void get_offset_range(hwaddr phys_addr,
                             ram_addr_t mapping_length,
                             DumpState *s,
                             hwaddr *p_offset,
                             hwaddr *p_filesz)
{
    GuestPhysBlock *block;
    hwaddr offset = s->memory_offset;
    int64_t size_in_block, start;

    /* When the memory is not stored into vmcore, offset will be -1 */
    *p_offset = -1;
    *p_filesz = 0;

    if (s->has_filter) {
        if (phys_addr < s->begin || phys_addr >= s->begin + s->length) {
            return;
        }
    }

    QTAILQ_FOREACH(block, &s->guest_phys_blocks.head, next) {
        if (s->has_filter) {
            if (block->target_start >= s->begin + s->length ||
                block->target_end <= s->begin) {
                /* This block is out of the range */
                continue;
            }

            if (s->begin <= block->target_start) {
                start = block->target_start;
            } else {
                start = s->begin;
            }

            size_in_block = block->target_end - start;
            if (s->begin + s->length < block->target_end) {
                size_in_block -= block->target_end - (s->begin + s->length);
            }
        } else {
            start = block->target_start;
            size_in_block = block->target_end - block->target_start;
        }

        if (phys_addr >= start && phys_addr < start + size_in_block) {
            *p_offset = phys_addr - start + offset;

            /* The offset range mapped from the vmcore file must not spill over
             * the GuestPhysBlock, clamp it. The rest of the mapping will be
             * zero-filled in memory at load time; see
             * <http://refspecs.linuxbase.org/elf/gabi4+/ch5.pheader.html>.
             */
            *p_filesz = phys_addr + mapping_length <= start + size_in_block ?
                        mapping_length :
                        size_in_block - (phys_addr - start);
            return;
        }

        offset += size_in_block;
    }
}

static void write_elf_loads(DumpState *s, Error **errp)
{
    hwaddr offset, filesz;
    MemoryMapping *memory_mapping;
    uint32_t phdr_index = 1;
    uint32_t max_index;
    Error *local_err = NULL;

    if (s->have_section) {
        max_index = s->sh_info;
    } else {
        max_index = s->phdr_num;
    }

    QTAILQ_FOREACH(memory_mapping, &s->list.head, next) {
        get_offset_range(memory_mapping->phys_addr,
                         memory_mapping->length,
                         s, &offset, &filesz);
        if (s->dump_info.d_class == ELFCLASS64) {
            write_elf64_load(s, memory_mapping, phdr_index++, offset,
                             filesz, &local_err);
        } else {
            write_elf32_load(s, memory_mapping, phdr_index++, offset,
                             filesz, &local_err);
        }

        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }

        if (phdr_index >= max_index) {
            break;
        }
    }
}

/* write elf header, PT_NOTE and elf note to vmcore. */
static void dump_begin(DumpState *s, Error **errp)
{
    Error *local_err = NULL;

    /*
     * the vmcore's format is:
     *   --------------
     *   |  elf header |
     *   --------------
     *   |  PT_NOTE    |
     *   --------------
     *   |  PT_LOAD    |
     *   --------------
     *   |  ......     |
     *   --------------
     *   |  PT_LOAD    |
     *   --------------
     *   |  sec_hdr    |
     *   --------------
     *   |  elf note   |
     *   --------------
     *   |  memory     |
     *   --------------
     *
     * we only know where the memory is saved after we write elf note into
     * vmcore.
     */

    /* write elf header to vmcore */
    if (s->dump_info.d_class == ELFCLASS64) {
        write_elf64_header(s, &local_err);
    } else {
        write_elf32_header(s, &local_err);
    }
    if (local_err) {
        error_propagate(errp, local_err);
        return;
    }

    if (s->dump_info.d_class == ELFCLASS64) {
        /* write PT_NOTE to vmcore */
        write_elf64_note(s, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }

        /* write all PT_LOAD to vmcore */
        write_elf_loads(s, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }

        /* write section to vmcore */
        if (s->have_section) {
            write_elf_section(s, 1, &local_err);
            if (local_err) {
                error_propagate(errp, local_err);
                return;
            }
        }

        /* write notes to vmcore */
        write_elf64_notes(fd_write_vmcore, s, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }
    } else {
        /* write PT_NOTE to vmcore */
        write_elf32_note(s, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }

        /* write all PT_LOAD to vmcore */
        write_elf_loads(s, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }

        /* write section to vmcore */
        if (s->have_section) {
            write_elf_section(s, 0, &local_err);
            if (local_err) {
                error_propagate(errp, local_err);
                return;
            }
        }

        /* write notes to vmcore */
        write_elf32_notes(fd_write_vmcore, s, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }
    }
}

static int get_next_block(DumpState *s, GuestPhysBlock *block)
{
    while (1) {
        block = QTAILQ_NEXT(block, next);
        if (!block) {
            /* no more block */
            return 1;
        }

        s->start = 0;
        s->next_block = block;
        if (s->has_filter) {
            if (block->target_start >= s->begin + s->length ||
                block->target_end <= s->begin) {
                /* This block is out of the range */
                continue;
            }

            if (s->begin > block->target_start) {
                s->start = s->begin - block->target_start;
            }
        }

        return 0;
    }
}

/* write all memory to vmcore */
static void dump_iterate(DumpState *s, Error **errp)
{
    GuestPhysBlock *block;
    int64_t size;
    Error *local_err = NULL;

    do {
        block = s->next_block;

        size = block->target_end - block->target_start;
        if (s->has_filter) {
            size -= s->start;
            if (s->begin + s->length < block->target_end) {
                size -= block->target_end - (s->begin + s->length);
            }
        }
        write_memory(s, block, s->start, size, &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            return;
        }

    } while (!get_next_block(s, block));
}

static void create_vmcore(DumpState *s, Error **errp)
{
    Error *local_err = NULL;

    dump_begin(s, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        return;
    }

    dump_iterate(s, errp);
}

static int write_start_flat_header(int fd)
{
    MakedumpfileHeader *mh;
    int ret = 0;

    QEMU_BUILD_BUG_ON(sizeof *mh > MAX_SIZE_MDF_HEADER);
    mh = g_malloc0(MAX_SIZE_MDF_HEADER);

    memcpy(mh->signature, MAKEDUMPFILE_SIGNATURE,
           MIN(sizeof mh->signature, sizeof MAKEDUMPFILE_SIGNATURE));

    mh->type = cpu_to_be64(TYPE_FLAT_HEADER);
    mh->version = cpu_to_be64(VERSION_FLAT_HEADER);

    size_t written_size;
    written_size = qemu_write_full(fd, mh, MAX_SIZE_MDF_HEADER);
    if (written_size != MAX_SIZE_MDF_HEADER) {
        ret = -1;
    }

    g_free(mh);
    return ret;
}

static int write_end_flat_header(int fd)
{
    MakedumpfileDataHeader mdh;

    mdh.offset = END_FLAG_FLAT_HEADER;
    mdh.buf_size = END_FLAG_FLAT_HEADER;

    size_t written_size;
    written_size = qemu_write_full(fd, &mdh, sizeof(mdh));
    if (written_size != sizeof(mdh)) {
        return -1;
    }

    return 0;
}

static int write_buffer(int fd, off_t offset, const void *buf, size_t size)
{
    size_t written_size;
    MakedumpfileDataHeader mdh;

    mdh.offset = cpu_to_be64(offset);
    mdh.buf_size = cpu_to_be64(size);

    written_size = qemu_write_full(fd, &mdh, sizeof(mdh));
    if (written_size != sizeof(mdh)) {
        return -1;
    }

    written_size = qemu_write_full(fd, buf, size);
    if (written_size != size) {
        return -1;
    }

    return 0;
}

static int buf_write_note(const void *buf, size_t size, void *opaque)
{
    DumpState *s = opaque;

    /* note_buf is not enough */
    if (s->note_buf_offset + size > s->note_size) {
        return -1;
    }

    memcpy(s->note_buf + s->note_buf_offset, buf, size);

    s->note_buf_offset += size;

    return 0;
}

/* write common header, sub header and elf note to vmcore */
static void create_header32(DumpState *s, Error **errp)
{
    DiskDumpHeader32 *dh = NULL;
    KdumpSubHeader32 *kh = NULL;
    size_t size;
    uint32_t block_size;
    uint32_t sub_hdr_size;
    uint32_t bitmap_blocks;
    uint32_t status = 0;
    uint64_t offset_note;
    Error *local_err = NULL;

    /* write common header, the version of kdump-compressed format is 6th */
    size = sizeof(DiskDumpHeader32);
    dh = g_malloc0(size);

    strncpy(dh->signature, KDUMP_SIGNATURE, strlen(KDUMP_SIGNATURE));
    dh->header_version = cpu_to_dump32(s, 6);
    block_size = s->dump_info.page_size;
    dh->block_size = cpu_to_dump32(s, block_size);
    sub_hdr_size = sizeof(struct KdumpSubHeader32) + s->note_size;
    sub_hdr_size = DIV_ROUND_UP(sub_hdr_size, block_size);
    dh->sub_hdr_size = cpu_to_dump32(s, sub_hdr_size);
    /* dh->max_mapnr may be truncated, full 64bit is in kh.max_mapnr_64 */
    dh->max_mapnr = cpu_to_dump32(s, MIN(s->max_mapnr, UINT_MAX));
    dh->nr_cpus = cpu_to_dump32(s, s->nr_cpus);
    bitmap_blocks = DIV_ROUND_UP(s->len_dump_bitmap, block_size) * 2;
    dh->bitmap_blocks = cpu_to_dump32(s, bitmap_blocks);
    strncpy(dh->utsname.machine, ELF_MACHINE_UNAME, sizeof(dh->utsname.machine));

    if (s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) {
        status |= DUMP_DH_COMPRESSED_ZLIB;
    }
#ifdef CONFIG_LZO
    if (s->flag_compress & DUMP_DH_COMPRESSED_LZO) {
        status |= DUMP_DH_COMPRESSED_LZO;
    }
#endif
#ifdef CONFIG_SNAPPY
    if (s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) {
        status |= DUMP_DH_COMPRESSED_SNAPPY;
    }
#endif
    dh->status = cpu_to_dump32(s, status);

    if (write_buffer(s->fd, 0, dh, size) < 0) {
        error_setg(errp, "dump: failed to write disk dump header");
        goto out;
    }

    /* write sub header */
    size = sizeof(KdumpSubHeader32);
    kh = g_malloc0(size);

    /* 64bit max_mapnr_64 */
    kh->max_mapnr_64 = cpu_to_dump64(s, s->max_mapnr);
    kh->phys_base = cpu_to_dump32(s, s->dump_info.phys_base);
    kh->dump_level = cpu_to_dump32(s, DUMP_LEVEL);

    offset_note = DISKDUMP_HEADER_BLOCKS * block_size + size;
    kh->offset_note = cpu_to_dump64(s, offset_note);
    kh->note_size = cpu_to_dump32(s, s->note_size);

    if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
                     block_size, kh, size) < 0) {
        error_setg(errp, "dump: failed to write kdump sub header");
        goto out;
    }

    /* write note */
    s->note_buf = g_malloc0(s->note_size);
    s->note_buf_offset = 0;

    /* use s->note_buf to store notes temporarily */
    write_elf32_notes(buf_write_note, s, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        goto out;
    }
    if (write_buffer(s->fd, offset_note, s->note_buf,
                     s->note_size) < 0) {
        error_setg(errp, "dump: failed to write notes");
        goto out;
    }

    /* get offset of dump_bitmap */
    s->offset_dump_bitmap = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size) *
                             block_size;

    /* get offset of page */
    s->offset_page = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size + bitmap_blocks) *
                     block_size;

out:
    g_free(dh);
    g_free(kh);
    g_free(s->note_buf);
}

/* write common header, sub header and elf note to vmcore */
static void create_header64(DumpState *s, Error **errp)
{
    DiskDumpHeader64 *dh = NULL;
    KdumpSubHeader64 *kh = NULL;
    size_t size;
    uint32_t block_size;
    uint32_t sub_hdr_size;
    uint32_t bitmap_blocks;
    uint32_t status = 0;
    uint64_t offset_note;
    Error *local_err = NULL;

    /* write common header, the version of kdump-compressed format is 6th */
    size = sizeof(DiskDumpHeader64);
    dh = g_malloc0(size);

    strncpy(dh->signature, KDUMP_SIGNATURE, strlen(KDUMP_SIGNATURE));
    dh->header_version = cpu_to_dump32(s, 6);
    block_size = s->dump_info.page_size;
    dh->block_size = cpu_to_dump32(s, block_size);
    sub_hdr_size = sizeof(struct KdumpSubHeader64) + s->note_size;
    sub_hdr_size = DIV_ROUND_UP(sub_hdr_size, block_size);
    dh->sub_hdr_size = cpu_to_dump32(s, sub_hdr_size);
    /* dh->max_mapnr may be truncated, full 64bit is in kh.max_mapnr_64 */
    dh->max_mapnr = cpu_to_dump32(s, MIN(s->max_mapnr, UINT_MAX));
    dh->nr_cpus = cpu_to_dump32(s, s->nr_cpus);
    bitmap_blocks = DIV_ROUND_UP(s->len_dump_bitmap, block_size) * 2;
    dh->bitmap_blocks = cpu_to_dump32(s, bitmap_blocks);
    strncpy(dh->utsname.machine, ELF_MACHINE_UNAME, sizeof(dh->utsname.machine));

    if (s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) {
        status |= DUMP_DH_COMPRESSED_ZLIB;
    }
#ifdef CONFIG_LZO
    if (s->flag_compress & DUMP_DH_COMPRESSED_LZO) {
        status |= DUMP_DH_COMPRESSED_LZO;
    }
#endif
#ifdef CONFIG_SNAPPY
    if (s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) {
        status |= DUMP_DH_COMPRESSED_SNAPPY;
    }
#endif
    dh->status = cpu_to_dump32(s, status);

    if (write_buffer(s->fd, 0, dh, size) < 0) {
        error_setg(errp, "dump: failed to write disk dump header");
        goto out;
    }

    /* write sub header */
    size = sizeof(KdumpSubHeader64);
    kh = g_malloc0(size);

    /* 64bit max_mapnr_64 */
    kh->max_mapnr_64 = cpu_to_dump64(s, s->max_mapnr);
    kh->phys_base = cpu_to_dump64(s, s->dump_info.phys_base);
    kh->dump_level = cpu_to_dump32(s, DUMP_LEVEL);

    offset_note = DISKDUMP_HEADER_BLOCKS * block_size + size;
    kh->offset_note = cpu_to_dump64(s, offset_note);
    kh->note_size = cpu_to_dump64(s, s->note_size);

    if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
                     block_size, kh, size) < 0) {
        error_setg(errp, "dump: failed to write kdump sub header");
        goto out;
    }

    /* write note */
    s->note_buf = g_malloc0(s->note_size);
    s->note_buf_offset = 0;

    /* use s->note_buf to store notes temporarily */
    write_elf64_notes(buf_write_note, s, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        goto out;
    }

    if (write_buffer(s->fd, offset_note, s->note_buf,
                     s->note_size) < 0) {
        error_setg(errp, "dump: failed to write notes");
        goto out;
    }

    /* get offset of dump_bitmap */
    s->offset_dump_bitmap = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size) *
                             block_size;

    /* get offset of page */
    s->offset_page = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size + bitmap_blocks) *
                     block_size;

out:
    g_free(dh);
    g_free(kh);
    g_free(s->note_buf);
}

static void write_dump_header(DumpState *s, Error **errp)
{
     Error *local_err = NULL;

    if (s->dump_info.d_class == ELFCLASS32) {
        create_header32(s, &local_err);
    } else {
        create_header64(s, &local_err);
    }
    if (local_err) {
        error_propagate(errp, local_err);
    }
}

static size_t dump_bitmap_get_bufsize(DumpState *s)
{
    return s->dump_info.page_size;
}

/*
 * set dump_bitmap sequencely. the bit before last_pfn is not allowed to be
 * rewritten, so if need to set the first bit, set last_pfn and pfn to 0.
 * set_dump_bitmap will always leave the recently set bit un-sync. And setting
 * (last bit + sizeof(buf) * 8) to 0 will do flushing the content in buf into
 * vmcore, ie. synchronizing un-sync bit into vmcore.
 */
static int set_dump_bitmap(uint64_t last_pfn, uint64_t pfn, bool value,
                           uint8_t *buf, DumpState *s)
{
    off_t old_offset, new_offset;
    off_t offset_bitmap1, offset_bitmap2;
    uint32_t byte, bit;
    size_t bitmap_bufsize = dump_bitmap_get_bufsize(s);
    size_t bits_per_buf = bitmap_bufsize * CHAR_BIT;

    /* should not set the previous place */
    assert(last_pfn <= pfn);

    /*
     * if the bit needed to be set is not cached in buf, flush the data in buf
     * to vmcore firstly.
     * making new_offset be bigger than old_offset can also sync remained data
     * into vmcore.
     */
    old_offset = bitmap_bufsize * (last_pfn / bits_per_buf);
    new_offset = bitmap_bufsize * (pfn / bits_per_buf);

    while (old_offset < new_offset) {
        /* calculate the offset and write dump_bitmap */
        offset_bitmap1 = s->offset_dump_bitmap + old_offset;
        if (write_buffer(s->fd, offset_bitmap1, buf,
                         bitmap_bufsize) < 0) {
            return -1;
        }

        /* dump level 1 is chosen, so 1st and 2nd bitmap are same */
        offset_bitmap2 = s->offset_dump_bitmap + s->len_dump_bitmap +
                         old_offset;
        if (write_buffer(s->fd, offset_bitmap2, buf,
                         bitmap_bufsize) < 0) {
            return -1;
        }

        memset(buf, 0, bitmap_bufsize);
        old_offset += bitmap_bufsize;
    }

    /* get the exact place of the bit in the buf, and set it */
    byte = (pfn % bits_per_buf) / CHAR_BIT;
    bit = (pfn % bits_per_buf) % CHAR_BIT;
    if (value) {
        buf[byte] |= 1u << bit;
    } else {
        buf[byte] &= ~(1u << bit);
    }

    return 0;
}

static uint64_t dump_paddr_to_pfn(DumpState *s, uint64_t addr)
{
    int target_page_shift = ctz32(s->dump_info.page_size);

    return (addr >> target_page_shift) - ARCH_PFN_OFFSET;
}

static uint64_t dump_pfn_to_paddr(DumpState *s, uint64_t pfn)
{
    int target_page_shift = ctz32(s->dump_info.page_size);

    return (pfn + ARCH_PFN_OFFSET) << target_page_shift;
}

/*
 * exam every page and return the page frame number and the address of the page.
 * bufptr can be NULL. note: the blocks here is supposed to reflect guest-phys
 * blocks, so block->target_start and block->target_end should be interal
 * multiples of the target page size.
 */
static bool get_next_page(GuestPhysBlock **blockptr, uint64_t *pfnptr,
                          uint8_t **bufptr, DumpState *s)
{
    GuestPhysBlock *block = *blockptr;
    hwaddr addr, target_page_mask = ~((hwaddr)s->dump_info.page_size - 1);
    uint8_t *buf;

    /* block == NULL means the start of the iteration */
    if (!block) {
        block = QTAILQ_FIRST(&s->guest_phys_blocks.head);
        *blockptr = block;
        assert((block->target_start & ~target_page_mask) == 0);
        assert((block->target_end & ~target_page_mask) == 0);
        *pfnptr = dump_paddr_to_pfn(s, block->target_start);
        if (bufptr) {
            *bufptr = block->host_addr;
        }
        return true;
    }

    *pfnptr = *pfnptr + 1;
    addr = dump_pfn_to_paddr(s, *pfnptr);

    if ((addr >= block->target_start) &&
        (addr + s->dump_info.page_size <= block->target_end)) {
        buf = block->host_addr + (addr - block->target_start);
    } else {
        /* the next page is in the next block */
        block = QTAILQ_NEXT(block, next);
        *blockptr = block;
        if (!block) {
            return false;
        }
        assert((block->target_start & ~target_page_mask) == 0);
        assert((block->target_end & ~target_page_mask) == 0);
        *pfnptr = dump_paddr_to_pfn(s, block->target_start);
        buf = block->host_addr;
    }

    if (bufptr) {
        *bufptr = buf;
    }

    return true;
}

static void write_dump_bitmap(DumpState *s, Error **errp)
{
    int ret = 0;
    uint64_t last_pfn, pfn;
    void *dump_bitmap_buf;
    size_t num_dumpable;
    GuestPhysBlock *block_iter = NULL;
    size_t bitmap_bufsize = dump_bitmap_get_bufsize(s);
    size_t bits_per_buf = bitmap_bufsize * CHAR_BIT;

    /* dump_bitmap_buf is used to store dump_bitmap temporarily */
    dump_bitmap_buf = g_malloc0(bitmap_bufsize);

    num_dumpable = 0;
    last_pfn = 0;

    /*
     * exam memory page by page, and set the bit in dump_bitmap corresponded
     * to the existing page.
     */
    while (get_next_page(&block_iter, &pfn, NULL, s)) {
        ret = set_dump_bitmap(last_pfn, pfn, true, dump_bitmap_buf, s);
        if (ret < 0) {
            error_setg(errp, "dump: failed to set dump_bitmap");
            goto out;
        }

        last_pfn = pfn;
        num_dumpable++;
    }

    /*
     * set_dump_bitmap will always leave the recently set bit un-sync. Here we
     * set the remaining bits from last_pfn to the end of the bitmap buffer to
     * 0. With those set, the un-sync bit will be synchronized into the vmcore.
     */
    if (num_dumpable > 0) {
        ret = set_dump_bitmap(last_pfn, last_pfn + bits_per_buf, false,
                              dump_bitmap_buf, s);
        if (ret < 0) {
            error_setg(errp, "dump: failed to sync dump_bitmap");
            goto out;
        }
    }

    /* number of dumpable pages that will be dumped later */
    s->num_dumpable = num_dumpable;

out:
    g_free(dump_bitmap_buf);
}

static void prepare_data_cache(DataCache *data_cache, DumpState *s,
                               off_t offset)
{
    data_cache->fd = s->fd;
    data_cache->data_size = 0;
    data_cache->buf_size = 4 * dump_bitmap_get_bufsize(s);
    data_cache->buf = g_malloc0(data_cache->buf_size);
    data_cache->offset = offset;
}

static int write_cache(DataCache *dc, const void *buf, size_t size,
                       bool flag_sync)
{
    /*
     * dc->buf_size should not be less than size, otherwise dc will never be
     * enough
     */
    assert(size <= dc->buf_size);

    /*
     * if flag_sync is set, synchronize data in dc->buf into vmcore.
     * otherwise check if the space is enough for caching data in buf, if not,
     * write the data in dc->buf to dc->fd and reset dc->buf
     */
    if ((!flag_sync && dc->data_size + size > dc->buf_size) ||
        (flag_sync && dc->data_size > 0)) {
        if (write_buffer(dc->fd, dc->offset, dc->buf, dc->data_size) < 0) {
            return -1;
        }

        dc->offset += dc->data_size;
        dc->data_size = 0;
    }

    if (!flag_sync) {
        memcpy(dc->buf + dc->data_size, buf, size);
        dc->data_size += size;
    }

    return 0;
}

static void free_data_cache(DataCache *data_cache)
{
    g_free(data_cache->buf);
}

static size_t get_len_buf_out(size_t page_size, uint32_t flag_compress)
{
    switch (flag_compress) {
    case DUMP_DH_COMPRESSED_ZLIB:
        return compressBound(page_size);

    case DUMP_DH_COMPRESSED_LZO:
        /*
         * LZO will expand incompressible data by a little amount. Please check
         * the following URL to see the expansion calculation:
         * http://www.oberhumer.com/opensource/lzo/lzofaq.php
         */
        return page_size + page_size / 16 + 64 + 3;

#ifdef CONFIG_SNAPPY
    case DUMP_DH_COMPRESSED_SNAPPY:
        return snappy_max_compressed_length(page_size);
#endif
    }
    return 0;
}

/*
 * check if the page is all 0
 */
static inline bool is_zero_page(const uint8_t *buf, size_t page_size)
{
    return buffer_is_zero(buf, page_size);
}

static void write_dump_pages(DumpState *s, Error **errp)
{
    int ret = 0;
    DataCache page_desc, page_data;
    size_t len_buf_out, size_out;
#ifdef CONFIG_LZO
    lzo_bytep wrkmem = NULL;
#endif
    uint8_t *buf_out = NULL;
    off_t offset_desc, offset_data;
    PageDescriptor pd, pd_zero;
    uint8_t *buf;
    GuestPhysBlock *block_iter = NULL;
    uint64_t pfn_iter;

    /* get offset of page_desc and page_data in dump file */
    offset_desc = s->offset_page;
    offset_data = offset_desc + sizeof(PageDescriptor) * s->num_dumpable;

    prepare_data_cache(&page_desc, s, offset_desc);
    prepare_data_cache(&page_data, s, offset_data);

    /* prepare buffer to store compressed data */
    len_buf_out = get_len_buf_out(s->dump_info.page_size, s->flag_compress);
    assert(len_buf_out != 0);

#ifdef CONFIG_LZO
    wrkmem = g_malloc(LZO1X_1_MEM_COMPRESS);
#endif

    buf_out = g_malloc(len_buf_out);

    /*
     * init zero page's page_desc and page_data, because every zero page
     * uses the same page_data
     */
    pd_zero.size = cpu_to_dump32(s, s->dump_info.page_size);
    pd_zero.flags = cpu_to_dump32(s, 0);
    pd_zero.offset = cpu_to_dump64(s, offset_data);
    pd_zero.page_flags = cpu_to_dump64(s, 0);
    buf = g_malloc0(s->dump_info.page_size);
    ret = write_cache(&page_data, buf, s->dump_info.page_size, false);
    g_free(buf);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write page data (zero page)");
        goto out;
    }

    offset_data += s->dump_info.page_size;

    /*
     * dump memory to vmcore page by page. zero page will all be resided in the
     * first page of page section
     */
    while (get_next_page(&block_iter, &pfn_iter, &buf, s)) {
        /* check zero page */
        if (is_zero_page(buf, s->dump_info.page_size)) {
            ret = write_cache(&page_desc, &pd_zero, sizeof(PageDescriptor),
                              false);
            if (ret < 0) {
                error_setg(errp, "dump: failed to write page desc");
                goto out;
            }
        } else {
            /*
             * not zero page, then:
             * 1. compress the page
             * 2. write the compressed page into the cache of page_data
             * 3. get page desc of the compressed page and write it into the
             *    cache of page_desc
             *
             * only one compression format will be used here, for
             * s->flag_compress is set. But when compression fails to work,
             * we fall back to save in plaintext.
             */
             size_out = len_buf_out;
             if ((s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) &&
                    (compress2(buf_out, (uLongf *)&size_out, buf,
                               s->dump_info.page_size, Z_BEST_SPEED) == Z_OK) &&
                    (size_out < s->dump_info.page_size)) {
                pd.flags = cpu_to_dump32(s, DUMP_DH_COMPRESSED_ZLIB);
                pd.size  = cpu_to_dump32(s, size_out);

                ret = write_cache(&page_data, buf_out, size_out, false);
                if (ret < 0) {
                    error_setg(errp, "dump: failed to write page data");
                    goto out;
                }
#ifdef CONFIG_LZO
            } else if ((s->flag_compress & DUMP_DH_COMPRESSED_LZO) &&
                    (lzo1x_1_compress(buf, s->dump_info.page_size, buf_out,
                    (lzo_uint *)&size_out, wrkmem) == LZO_E_OK) &&
                    (size_out < s->dump_info.page_size)) {
                pd.flags = cpu_to_dump32(s, DUMP_DH_COMPRESSED_LZO);
                pd.size  = cpu_to_dump32(s, size_out);

                ret = write_cache(&page_data, buf_out, size_out, false);
                if (ret < 0) {
                    error_setg(errp, "dump: failed to write page data");
                    goto out;
                }
#endif
#ifdef CONFIG_SNAPPY
            } else if ((s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) &&
                    (snappy_compress((char *)buf, s->dump_info.page_size,
                    (char *)buf_out, &size_out) == SNAPPY_OK) &&
                    (size_out < s->dump_info.page_size)) {
                pd.flags = cpu_to_dump32(s, DUMP_DH_COMPRESSED_SNAPPY);
                pd.size  = cpu_to_dump32(s, size_out);

                ret = write_cache(&page_data, buf_out, size_out, false);
                if (ret < 0) {
                    error_setg(errp, "dump: failed to write page data");
                    goto out;
                }
#endif
            } else {
                /*
                 * fall back to save in plaintext, size_out should be
                 * assigned the target's page size
                 */
                pd.flags = cpu_to_dump32(s, 0);
                size_out = s->dump_info.page_size;
                pd.size = cpu_to_dump32(s, size_out);

                ret = write_cache(&page_data, buf,
                                  s->dump_info.page_size, false);
                if (ret < 0) {
                    error_setg(errp, "dump: failed to write page data");
                    goto out;
                }
            }

            /* get and write page desc here */
            pd.page_flags = cpu_to_dump64(s, 0);
            pd.offset = cpu_to_dump64(s, offset_data);
            offset_data += size_out;

            ret = write_cache(&page_desc, &pd, sizeof(PageDescriptor), false);
            if (ret < 0) {
                error_setg(errp, "dump: failed to write page desc");
                goto out;
            }
        }
    }

    ret = write_cache(&page_desc, NULL, 0, true);
    if (ret < 0) {
        error_setg(errp, "dump: failed to sync cache for page_desc");
        goto out;
    }
    ret = write_cache(&page_data, NULL, 0, true);
    if (ret < 0) {
        error_setg(errp, "dump: failed to sync cache for page_data");
        goto out;
    }

out:
    free_data_cache(&page_desc);
    free_data_cache(&page_data);

#ifdef CONFIG_LZO
    g_free(wrkmem);
#endif

    g_free(buf_out);
}

static void create_kdump_vmcore(DumpState *s, Error **errp)
{
    int ret;
    Error *local_err = NULL;

    /*
     * the kdump-compressed format is:
     *                                               File offset
     *  +------------------------------------------+ 0x0
     *  |    main header (struct disk_dump_header) |
     *  |------------------------------------------+ block 1
     *  |    sub header (struct kdump_sub_header)  |
     *  |------------------------------------------+ block 2
     *  |            1st-dump_bitmap               |
     *  |------------------------------------------+ block 2 + X blocks
     *  |            2nd-dump_bitmap               | (aligned by block)
     *  |------------------------------------------+ block 2 + 2 * X blocks
     *  |  page desc for pfn 0 (struct page_desc)  | (aligned by block)
     *  |  page desc for pfn 1 (struct page_desc)  |
     *  |                    :                     |
     *  |------------------------------------------| (not aligned by block)
     *  |         page data (pfn 0)                |
     *  |         page data (pfn 1)                |
     *  |                    :                     |
     *  +------------------------------------------+
     */

    ret = write_start_flat_header(s->fd);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write start flat header");
        return;
    }

    write_dump_header(s, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        return;
    }

    write_dump_bitmap(s, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        return;
    }

    write_dump_pages(s, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        return;
    }

    ret = write_end_flat_header(s->fd);
    if (ret < 0) {
        error_setg(errp, "dump: failed to write end flat header");
        return;
    }
}

static ram_addr_t get_start_block(DumpState *s)
{
    GuestPhysBlock *block;

    if (!s->has_filter) {
        s->next_block = QTAILQ_FIRST(&s->guest_phys_blocks.head);
        return 0;
    }

    QTAILQ_FOREACH(block, &s->guest_phys_blocks.head, next) {
        if (block->target_start >= s->begin + s->length ||
            block->target_end <= s->begin) {
            /* This block is out of the range */
            continue;
        }

        s->next_block = block;
        if (s->begin > block->target_start) {
            s->start = s->begin - block->target_start;
        } else {
            s->start = 0;
        }
        return s->start;
    }

    return -1;
}

static void get_max_mapnr(DumpState *s)
{
    GuestPhysBlock *last_block;

    last_block = QTAILQ_LAST(&s->guest_phys_blocks.head, GuestPhysBlockHead);
    s->max_mapnr = dump_paddr_to_pfn(s, last_block->target_end);
}

static DumpState dump_state_global = { .status = DUMP_STATUS_NONE };

static void dump_state_prepare(DumpState *s)
{
    /* zero the struct, setting status to active */
    *s = (DumpState) { .status = DUMP_STATUS_ACTIVE };
}

bool dump_in_progress(void)
{
    DumpState *state = &dump_state_global;
    return (state->status == DUMP_STATUS_ACTIVE);
}

static void dump_init(DumpState *s, int fd, bool has_format,
                      DumpGuestMemoryFormat format, bool paging, bool has_filter,
                      int64_t begin, int64_t length, Error **errp)
{
    CPUState *cpu;
    int nr_cpus;
    Error *err = NULL;
    int ret;

    s->has_format = has_format;
    s->format = format;

    /* kdump-compressed is conflict with paging and filter */
    if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
        assert(!paging && !has_filter);
    }

    if (runstate_is_running()) {
        vm_stop(RUN_STATE_SAVE_VM);
        s->resume = true;
    } else {
        s->resume = false;
    }

    /* If we use KVM, we should synchronize the registers before we get dump
     * info or physmap info.
     */
    cpu_synchronize_all_states();
    nr_cpus = 0;
    CPU_FOREACH(cpu) {
        nr_cpus++;
    }

    s->fd = fd;
    s->has_filter = has_filter;
    s->begin = begin;
    s->length = length;

    memory_mapping_list_init(&s->list);

    guest_phys_blocks_init(&s->guest_phys_blocks);
    guest_phys_blocks_append(&s->guest_phys_blocks);

    s->start = get_start_block(s);
    if (s->start == -1) {
        error_setg(errp, QERR_INVALID_PARAMETER, "begin");
        goto cleanup;
    }

    /* get dump info: endian, class and architecture.
     * If the target architecture is not supported, cpu_get_dump_info() will
     * return -1.
     */
    ret = cpu_get_dump_info(&s->dump_info, &s->guest_phys_blocks);
    if (ret < 0) {
        error_setg(errp, QERR_UNSUPPORTED);
        goto cleanup;
    }

    if (!s->dump_info.page_size) {
        s->dump_info.page_size = TARGET_PAGE_SIZE;
    }

    s->note_size = cpu_get_note_size(s->dump_info.d_class,
                                     s->dump_info.d_machine, nr_cpus);
    if (s->note_size < 0) {
        error_setg(errp, QERR_UNSUPPORTED);
        goto cleanup;
    }

    /* get memory mapping */
    if (paging) {
        qemu_get_guest_memory_mapping(&s->list, &s->guest_phys_blocks, &err);
        if (err != NULL) {
            error_propagate(errp, err);
            goto cleanup;
        }
    } else {
        qemu_get_guest_simple_memory_mapping(&s->list, &s->guest_phys_blocks);
    }

    s->nr_cpus = nr_cpus;

    get_max_mapnr(s);

    uint64_t tmp;
    tmp = DIV_ROUND_UP(DIV_ROUND_UP(s->max_mapnr, CHAR_BIT),
                       s->dump_info.page_size);
    s->len_dump_bitmap = tmp * s->dump_info.page_size;

    /* init for kdump-compressed format */
    if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
        switch (format) {
        case DUMP_GUEST_MEMORY_FORMAT_KDUMP_ZLIB:
            s->flag_compress = DUMP_DH_COMPRESSED_ZLIB;
            break;

        case DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO:
#ifdef CONFIG_LZO
            if (lzo_init() != LZO_E_OK) {
                error_setg(errp, "failed to initialize the LZO library");
                goto cleanup;
            }
#endif
            s->flag_compress = DUMP_DH_COMPRESSED_LZO;
            break;

        case DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY:
            s->flag_compress = DUMP_DH_COMPRESSED_SNAPPY;
            break;

        default:
            s->flag_compress = 0;
        }

        return;
    }

    if (s->has_filter) {
        memory_mapping_filter(&s->list, s->begin, s->length);
    }

    /*
     * calculate phdr_num
     *
     * the type of ehdr->e_phnum is uint16_t, so we should avoid overflow
     */
    s->phdr_num = 1; /* PT_NOTE */
    if (s->list.num < UINT16_MAX - 2) {
        s->phdr_num += s->list.num;
        s->have_section = false;
    } else {
        s->have_section = true;
        s->phdr_num = PN_XNUM;
        s->sh_info = 1; /* PT_NOTE */

        /* the type of shdr->sh_info is uint32_t, so we should avoid overflow */
        if (s->list.num <= UINT32_MAX - 1) {
            s->sh_info += s->list.num;
        } else {
            s->sh_info = UINT32_MAX;
        }
    }

    if (s->dump_info.d_class == ELFCLASS64) {
        if (s->have_section) {
            s->memory_offset = sizeof(Elf64_Ehdr) +
                               sizeof(Elf64_Phdr) * s->sh_info +
                               sizeof(Elf64_Shdr) + s->note_size;
        } else {
            s->memory_offset = sizeof(Elf64_Ehdr) +
                               sizeof(Elf64_Phdr) * s->phdr_num + s->note_size;
        }
    } else {
        if (s->have_section) {
            s->memory_offset = sizeof(Elf32_Ehdr) +
                               sizeof(Elf32_Phdr) * s->sh_info +
                               sizeof(Elf32_Shdr) + s->note_size;
        } else {
            s->memory_offset = sizeof(Elf32_Ehdr) +
                               sizeof(Elf32_Phdr) * s->phdr_num + s->note_size;
        }
    }

    return;

cleanup:
    dump_cleanup(s);
}

/* this operation might be time consuming. */
static void dump_process(DumpState *s, Error **errp)
{
    Error *local_err = NULL;

    if (s->has_format && s->format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
        create_kdump_vmcore(s, &local_err);
    } else {
        create_vmcore(s, &local_err);
    }

    s->status = (local_err ? DUMP_STATUS_FAILED : DUMP_STATUS_COMPLETED);
    error_propagate(errp, local_err);

    dump_cleanup(s);
}

static void *dump_thread(void *data)
{
    Error *err = NULL;
    DumpState *s = (DumpState *)data;

    dump_process(s, &err);

    if (err) {
        /* TODO: notify user the error */
        error_free(err);
    }
    return NULL;
}

void qmp_dump_guest_memory(bool paging, const char *file,
                           bool has_detach, bool detach,
                           bool has_begin, int64_t begin, bool has_length,
                           int64_t length, bool has_format,
                           DumpGuestMemoryFormat format, Error **errp)
{
    const char *p;
    int fd = -1;
    DumpState *s;
    Error *local_err = NULL;
    bool detach_p = false;

    if (runstate_check(RUN_STATE_INMIGRATE)) {
        error_setg(errp, "Dump not allowed during incoming migration.");
        return;
    }

    /* if there is a dump in background, we should wait until the dump
     * finished */
    if (dump_in_progress()) {
        error_setg(errp, "There is a dump in process, please wait.");
        return;
    }

    /*
     * kdump-compressed format need the whole memory dumped, so paging or
     * filter is not supported here.
     */
    if ((has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) &&
        (paging || has_begin || has_length)) {
        error_setg(errp, "kdump-compressed format doesn't support paging or "
                         "filter");
        return;
    }
    if (has_begin && !has_length) {
        error_setg(errp, QERR_MISSING_PARAMETER, "length");
        return;
    }
    if (!has_begin && has_length) {
        error_setg(errp, QERR_MISSING_PARAMETER, "begin");
        return;
    }
    if (has_detach) {
        detach_p = detach;
    }

    /* check whether lzo/snappy is supported */
#ifndef CONFIG_LZO
    if (has_format && format == DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO) {
        error_setg(errp, "kdump-lzo is not available now");
        return;
    }
#endif

#ifndef CONFIG_SNAPPY
    if (has_format && format == DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY) {
        error_setg(errp, "kdump-snappy is not available now");
        return;
    }
#endif

#if !defined(WIN32)
    if (strstart(file, "fd:", &p)) {
        fd = monitor_get_fd(cur_mon, p, errp);
        if (fd == -1) {
            return;
        }
    }
#endif

    if  (strstart(file, "file:", &p)) {
        fd = qemu_open(p, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, S_IRUSR);
        if (fd < 0) {
            error_setg_file_open(errp, errno, p);
            return;
        }
    }

    if (fd == -1) {
        error_setg(errp, QERR_INVALID_PARAMETER, "protocol");
        return;
    }

    s = &dump_state_global;
    dump_state_prepare(s);

    dump_init(s, fd, has_format, format, paging, has_begin,
              begin, length, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        s->status = DUMP_STATUS_FAILED;
        return;
    }

    if (detach_p) {
        /* detached dump */
        qemu_thread_create(&s->dump_thread, "dump_thread", dump_thread,
                           s, QEMU_THREAD_DETACHED);
    } else {
        /* sync dump */
        dump_process(s, errp);
    }
}

DumpGuestMemoryCapability *qmp_query_dump_guest_memory_capability(Error **errp)
{
    DumpGuestMemoryFormatList *item;
    DumpGuestMemoryCapability *cap =
                                  g_malloc0(sizeof(DumpGuestMemoryCapability));

    /* elf is always available */
    item = g_malloc0(sizeof(DumpGuestMemoryFormatList));
    cap->formats = item;
    item->value = DUMP_GUEST_MEMORY_FORMAT_ELF;

    /* kdump-zlib is always available */
    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
    item = item->next;
    item->value = DUMP_GUEST_MEMORY_FORMAT_KDUMP_ZLIB;

    /* add new item if kdump-lzo is available */
#ifdef CONFIG_LZO
    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
    item = item->next;
    item->value = DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO;
#endif

    /* add new item if kdump-snappy is available */
#ifdef CONFIG_SNAPPY
    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
    item = item->next;
    item->value = DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY;
#endif

    return cap;
}