summaryrefslogtreecommitdiff
path: root/kern/thread.c
blob: 9c82af5eca72b59659e45ba5edb698da320bb3b9 (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
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
/* 
 * Mach Operating System
 * Copyright (c) 1994-1987 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 *	File:	kern/thread.c
 *	Author:	Avadis Tevanian, Jr., Michael Wayne Young, David Golub
 *	Date:	1986
 *
 *	Thread management primitives implementation.
 */

#include <kern/printf.h>
#include <mach/std_types.h>
#include <mach/policy.h>
#include <mach/thread_info.h>
#include <mach/thread_special_ports.h>
#include <mach/thread_status.h>
#include <mach/time_value.h>
#include <machine/vm_param.h>
#include <kern/ast.h>
#include <kern/counters.h>
#include <kern/debug.h>
#include <kern/eventcount.h>
#include <kern/ipc_mig.h>
#include <kern/ipc_tt.h>
#include <kern/processor.h>
#include <kern/queue.h>
#include <kern/sched.h>
#include <kern/sched_prim.h>
#include <kern/syscall_subr.h>
#include <kern/thread.h>
#include <kern/thread_swap.h>
#include <kern/host.h>
#include <kern/kalloc.h>
#include <kern/slab.h>
#include <kern/mach_clock.h>
#include <vm/vm_kern.h>
#include <vm/vm_user.h>
#include <ipc/ipc_kmsg.h>
#include <ipc/ipc_port.h>
#include <ipc/mach_msg.h>
#include <ipc/mach_port.h>
#include <machine/machspl.h>		/* for splsched */
#include <machine/pcb.h>
#include <machine/thread.h>		/* for MACHINE_STACK */

thread_t active_threads[NCPUS];
vm_offset_t active_stacks[NCPUS];

struct kmem_cache thread_cache;

queue_head_t		reaper_queue;
decl_simple_lock_data(,	reaper_lock)

/* private */
struct thread	thread_template;

#if	MACH_DEBUG
#define	STACK_MARKER	0xdeadbeefU
boolean_t		stack_check_usage = FALSE;
decl_simple_lock_data(,	stack_usage_lock)
vm_size_t		stack_max_usage = 0;
#endif	/* MACH_DEBUG */

/*
 *	Machine-dependent code must define:
 *		pcb_init
 *		pcb_terminate
 *		pcb_collect
 *
 *	The thread->pcb field is reserved for machine-dependent code.
 */

#ifdef	MACHINE_STACK
/*
 *	Machine-dependent code must define:
 *		stack_alloc_try
 *		stack_alloc
 *		stack_free
 *		stack_handoff
 *		stack_collect
 */
#else	/* MACHINE_STACK */
/*
 *	We allocate stacks from generic kernel VM.
 *	Machine-dependent code must define:
 *		stack_attach
 *		stack_detach
 *		stack_handoff
 *
 *	The stack_free_list can only be accessed at splsched,
 *	because stack_alloc_try/thread_invoke operate at splsched.
 */

decl_simple_lock_data(, stack_lock_data)/* splsched only */
#define stack_lock()	simple_lock(&stack_lock_data)
#define stack_unlock()	simple_unlock(&stack_lock_data)

/*
 * We allocate kernel stacks using the slab allocator.
 */
static struct kmem_cache stack_cache;

/*
 *	stack_alloc_try:
 *
 *	Non-blocking attempt to allocate a kernel stack.
 *	Called at splsched with the thread locked.
 */

boolean_t stack_alloc_try(
	thread_t	thread,
	void		(*resume)(thread_t))
{
	vm_offset_t stack;

	stack = kmem_cache_alloc(&stack_cache);
	assert ((stack & (KERNEL_STACK_SIZE-1)) == 0);

#if	MACH_DEBUG
	if (stack)
		stack_init(stack);
#endif	/* MACH_DEBUG */
	if (! stack)
		stack = thread->stack_privilege;

	if (stack != 0) {
		stack_attach(thread, stack, resume);
		return TRUE;
	} else {
		return FALSE;
	}
}

/*
 *	stack_alloc:
 *
 *	Allocate a kernel stack for a thread.
 */

kern_return_t stack_alloc(
	thread_t	thread,
	void		(*resume)(thread_t))
{
	if (! stack_alloc_try (thread, resume))
		return KERN_RESOURCE_SHORTAGE;

	return KERN_SUCCESS;
}

/*
 *	stack_free:
 *
 *	Free a thread's kernel stack.
 *	Called at splsched with the thread locked.
 */

void stack_free(
	thread_t thread)
{
	vm_offset_t stack;

	stack = stack_detach(thread);

	if (stack != thread->stack_privilege)
		kmem_cache_free (&stack_cache, stack);
}

/*
 *	stack_collect:
 *
 *	Free excess kernel stacks.
 *	May block.
 */

void stack_collect(void)
{
}
#endif	/* MACHINE_STACK */

/*
 *	stack_privilege:
 *
 *	stack_alloc_try on this thread must always succeed.
 */

void stack_privilege(
	thread_t thread)
{
	/*
	 *	This implementation only works for the current thread.
	 */

	if (thread != current_thread())
		panic("stack_privilege");

	if (thread->stack_privilege == 0)
		thread->stack_privilege = current_stack();
}

void thread_init(void)
{
	kmem_cache_init(&thread_cache, "thread", sizeof(struct thread), 0,
			NULL, 0);

	/*
	 *	Kernel stacks should be naturally aligned, so that it
	 *	is easy to find the starting/ending addresses of a
	 *	stack given an address in the middle.
	 */
	kmem_cache_init(&stack_cache, "stack",
			KERNEL_STACK_SIZE, KERNEL_STACK_SIZE,
			NULL, 0);

	/*
	 *	Fill in a template thread for fast initialization.
	 *	[Fields that must be (or are typically) reset at
	 *	time of creation are so noted.]
	 */

	/* thread_template.links (none) */
	thread_template.runq = RUN_QUEUE_NULL;

	/* thread_template.task (later) */
	/* thread_template.thread_list (later) */
	/* thread_template.pset_threads (later) */

	/* thread_template.lock (later) */
	/* one ref for being alive; one for the guy who creates the thread */
	thread_template.ref_count = 2;

	thread_template.pcb = (pcb_t) 0;		/* (reset) */
	thread_template.kernel_stack = (vm_offset_t) 0;
	thread_template.stack_privilege = (vm_offset_t) 0;

	thread_template.wait_event = 0;
	/* thread_template.suspend_count (later) */
	thread_template.wait_result = KERN_SUCCESS;
	thread_template.wake_active = FALSE;
	thread_template.state = TH_SUSP | TH_SWAPPED;
	thread_template.swap_func = thread_bootstrap_return;

/*	thread_template.priority (later) */
	thread_template.max_priority = BASEPRI_USER;
/*	thread_template.sched_pri (later - compute_priority) */
#if	MACH_FIXPRI
	thread_template.sched_data = 0;
	thread_template.policy = POLICY_TIMESHARE;
#endif	/* MACH_FIXPRI */
	thread_template.depress_priority = -1;
	thread_template.cpu_usage = 0;
	thread_template.sched_usage = 0;
	/* thread_template.sched_stamp (later) */

	thread_template.recover = (vm_offset_t) 0;
	thread_template.vm_privilege = FALSE;

	thread_template.user_stop_count = 1;

	/* thread_template.<IPC structures> (later) */

	timer_init(&(thread_template.user_timer));
	timer_init(&(thread_template.system_timer));
	thread_template.user_timer_save.low = 0;
	thread_template.user_timer_save.high = 0;
	thread_template.system_timer_save.low = 0;
	thread_template.system_timer_save.high = 0;
	thread_template.cpu_delta = 0;
	thread_template.sched_delta = 0;

	thread_template.active = FALSE; /* reset */
	thread_template.ast = AST_ZILCH;

	/* thread_template.processor_set (later) */
	thread_template.bound_processor = PROCESSOR_NULL;
#if	MACH_HOST
	thread_template.may_assign = TRUE;
	thread_template.assign_active = FALSE;
#endif	/* MACH_HOST */

#if	NCPUS > 1
	/* thread_template.last_processor  (later) */
#endif	/* NCPUS > 1 */

	/*
	 *	Initialize other data structures used in
	 *	this module.
	 */

	queue_init(&reaper_queue);
	simple_lock_init(&reaper_lock);

#ifndef	MACHINE_STACK
	simple_lock_init(&stack_lock_data);
#endif	/* MACHINE_STACK */

#if	MACH_DEBUG
	simple_lock_init(&stack_usage_lock);
#endif	/* MACH_DEBUG */

	/*
	 *	Initialize any machine-dependent
	 *	per-thread structures necessary.
	 */

	pcb_module_init();
}

kern_return_t thread_create(
	task_t	parent_task,
	thread_t	*child_thread)		/* OUT */
{
	thread_t	new_thread;
	processor_set_t	pset;

	if (parent_task == TASK_NULL)
		return KERN_INVALID_ARGUMENT;

	/*
	 *	Allocate a thread and initialize static fields
	 */

	new_thread = (thread_t) kmem_cache_alloc(&thread_cache);

	if (new_thread == THREAD_NULL)
		return KERN_RESOURCE_SHORTAGE;

	*new_thread = thread_template;

	record_time_stamp (&new_thread->creation_time);

	/*
	 *	Initialize runtime-dependent fields
	 */

	new_thread->task = parent_task;
	simple_lock_init(&new_thread->lock);
	new_thread->sched_stamp = sched_tick;
	thread_timeout_setup(new_thread);

	/*
	 *	Create a pcb.  The kernel stack is created later,
	 *	when the thread is swapped-in.
	 */
	pcb_init(new_thread);

	ipc_thread_init(new_thread);

	/*
	 *	Find the processor set for the parent task.
	 */
	task_lock(parent_task);
	pset = parent_task->processor_set;
	pset_reference(pset);
	task_unlock(parent_task);

	/*
	 *	Lock both the processor set and the task,
	 *	so that the thread can be added to both
	 *	simultaneously.  Processor set must be
	 *	locked first.
	 */

    Restart:
	pset_lock(pset);
	task_lock(parent_task);

	/*
	 *	If the task has changed processor sets,
	 *	catch up (involves lots of lock juggling).
	 */
	{
	    processor_set_t	cur_pset;

	    cur_pset = parent_task->processor_set;
	    if (!cur_pset->active)
		cur_pset = &default_pset;

	    if (cur_pset != pset) {
		pset_reference(cur_pset);
		task_unlock(parent_task);
		pset_unlock(pset);
		pset_deallocate(pset);
		pset = cur_pset;
		goto Restart;
	    }
	}

	/*
	 *	Set the thread`s priority from the pset and task.
	 */

	new_thread->priority = parent_task->priority;
	if (pset->max_priority > new_thread->max_priority)
		new_thread->max_priority = pset->max_priority;
	if (new_thread->max_priority > new_thread->priority)
		new_thread->priority = new_thread->max_priority;
	/*
	 *	Don't need to lock thread here because it can't
	 *	possibly execute and no one else knows about it.
	 */
	compute_priority(new_thread, TRUE);

	/*
	 *	Thread is suspended if the task is.  Add 1 to
	 *	suspend count since thread is created in suspended
	 *	state.
	 */
	new_thread->suspend_count = parent_task->suspend_count + 1;

	/*
	 *	Add the thread to the processor set.
	 *	If the pset is empty, suspend the thread again.
	 */

	pset_add_thread(pset, new_thread);
	if (pset->empty)
		new_thread->suspend_count++;

#if	HW_FOOTPRINT
	/*
	 *	Need to set last_processor, idle processor would be best, but
	 *	that requires extra locking nonsense.  Go for tail of
	 *	processors queue to avoid master.
	 */
	if (!pset->empty) {
		new_thread->last_processor = 
			(processor_t)queue_first(&pset->processors);
	}
	else {
		/*
		 *	Thread created in empty processor set.  Pick
		 *	master processor as an acceptable legal value.
		 */
		new_thread->last_processor = master_processor;
	}
#else	/* HW_FOOTPRINT */
	/*
	 *	Don't need to initialize because the context switch
	 *	code will set it before it can be used.
	 */
#endif	/* HW_FOOTPRINT */

#if	MACH_PCSAMPLE
	new_thread->pc_sample.seqno = 0;
	new_thread->pc_sample.sampletypes = 0;
#endif	/* MACH_PCSAMPLE */

	new_thread->pc_sample.buffer = 0;
	/*
	 *	Add the thread to the task`s list of threads.
	 *	The new thread holds another reference to the task.
	 */

	parent_task->ref_count++;

	parent_task->thread_count++;
	queue_enter(&parent_task->thread_list, new_thread, thread_t,
					thread_list);

	/*
	 *	Finally, mark the thread active.
	 */

	new_thread->active = TRUE;

	if (!parent_task->active) {
		task_unlock(parent_task);
		pset_unlock(pset);
		(void) thread_terminate(new_thread);
		/* release ref we would have given our caller */
		thread_deallocate(new_thread);
		return KERN_FAILURE;
	}
	task_unlock(parent_task);
	pset_unlock(pset);

	ipc_thread_enable(new_thread);

	*child_thread = new_thread;
	return KERN_SUCCESS;
}

unsigned int thread_deallocate_stack = 0;

void thread_deallocate(
	thread_t	thread)
{
	spl_t		s;
	task_t		task;
	processor_set_t	pset;

	time_value_t	user_time, system_time;

	if (thread == THREAD_NULL)
		return;

	/*
	 *	First, check for new count > 0 (the common case).
	 *	Only the thread needs to be locked.
	 */
	s = splsched();
	thread_lock(thread);
	if (--thread->ref_count > 0) {
		thread_unlock(thread);
		(void) splx(s);
		return;
	}

	/*
	 *	Count is zero.  However, the task's and processor set's
	 *	thread lists have implicit references to
	 *	the thread, and may make new ones.  Their locks also
	 *	dominate the thread lock.  To check for this, we
	 *	temporarily restore the one thread reference, unlock
	 *	the thread, and then lock the other structures in
	 *	the proper order.
	 */
	thread->ref_count = 1;
	thread_unlock(thread);
	(void) splx(s);

	pset = thread->processor_set;
	pset_lock(pset);

#if	MACH_HOST
	/*
	 *	The thread might have moved.
	 */
	while (pset != thread->processor_set) {
	    pset_unlock(pset);
	    pset = thread->processor_set;
	    pset_lock(pset);
	}
#endif	/* MACH_HOST */

	task = thread->task;
	task_lock(task);

	s = splsched();
	thread_lock(thread);

	if (--thread->ref_count > 0) {
		/*
		 *	Task or processor_set made extra reference.
		 */
		thread_unlock(thread);
		(void) splx(s);
		task_unlock(task);
		pset_unlock(pset);
		return;
	}

	/*
	 *	Thread has no references - we can remove it.
	 */

	/*
	 *	Remove pending timeouts.
	 */
	reset_timeout_check(&thread->timer);

	reset_timeout_check(&thread->depress_timer);
	thread->depress_priority = -1;

	/*
	 *	Accumulate times for dead threads in task.
	 */
	thread_read_times(thread, &user_time, &system_time);
	time_value_add(&task->total_user_time, &user_time);
	time_value_add(&task->total_system_time, &system_time);

	/*
	 *	Remove thread from task list and processor_set threads list.
	 */
	task->thread_count--;
	queue_remove(&task->thread_list, thread, thread_t, thread_list);

	pset_remove_thread(pset, thread);

	thread_unlock(thread);		/* no more references - safe */
	(void) splx(s);
	task_unlock(task);
	pset_unlock(pset);
	pset_deallocate(pset);

	/*
	 *	A couple of quick sanity checks
	 */

	if (thread == current_thread()) {
	    panic("thread deallocating itself");
	}
	if ((thread->state & ~(TH_RUN | TH_HALTED | TH_SWAPPED)) != TH_SUSP)
		panic("unstopped thread destroyed!");

	/*
	 *	Deallocate the task reference, since we know the thread
	 *	is not running.
	 */
	task_deallocate(thread->task);			/* may block */

	/*
	 *	Clean up any machine-dependent resources.
	 */
	if ((thread->state & TH_SWAPPED) == 0) {
		splsched();
		stack_free(thread);
		(void) splx(s);
		thread_deallocate_stack++;
	}
	/*
	 * Rattle the event count machinery (gag)
	 */
	evc_notify_abort(thread);

	pcb_terminate(thread);
	kmem_cache_free(&thread_cache, (vm_offset_t) thread);
}

void thread_reference(
	thread_t	thread)
{
	spl_t		s;

	if (thread == THREAD_NULL)
		return;

	s = splsched();
	thread_lock(thread);
	thread->ref_count++;
	thread_unlock(thread);
	(void) splx(s);
}

/*
 *	thread_terminate:
 *
 *	Permanently stop execution of the specified thread.
 *
 *	A thread to be terminated must be allowed to clean up any state
 *	that it has before it exits.  The thread is broken out of any
 *	wait condition that it is in, and signalled to exit.  It then
 *	cleans up its state and calls thread_halt_self on its way out of
 *	the kernel.  The caller waits for the thread to halt, terminates
 *	its IPC state, and then deallocates it.
 *
 *	If the caller is the current thread, it must still exit the kernel
 *	to clean up any state (thread and port references, messages, etc).
 *	When it exits the kernel, it then terminates its IPC state and
 *	queues itself for the reaper thread, which will wait for the thread
 *	to stop and then deallocate it.  (A thread cannot deallocate itself,
 *	since it needs a kernel stack to execute.)
 */
kern_return_t thread_terminate(
	thread_t	thread)
{
	thread_t		cur_thread = current_thread();
	task_t			cur_task;
	spl_t			s;

	if (thread == THREAD_NULL)
		return KERN_INVALID_ARGUMENT;

	/*
	 *	Break IPC control over the thread.
	 */
	ipc_thread_disable(thread);

	if (thread == cur_thread) {

	    /*
	     *	Current thread will queue itself for reaper when
	     *	exiting kernel.
	     */
	    s = splsched();
	    thread_lock(thread);
	    if (thread->active) {
		    thread->active = FALSE;
		    thread_ast_set(thread, AST_TERMINATE);
	    }
	    thread_unlock(thread);
	    ast_on(cpu_number(), AST_TERMINATE);
	    splx(s);
	    return KERN_SUCCESS;
	}

	/*
	 *	Lock both threads and the current task
	 *	to check termination races and prevent deadlocks.
	 */
	cur_task = current_task();
	task_lock(cur_task);
	s = splsched();
	if ((vm_offset_t)thread < (vm_offset_t)cur_thread) {
		thread_lock(thread);
		thread_lock(cur_thread);
	}
	else {
		thread_lock(cur_thread);
		thread_lock(thread);
	}

	/*
	 *	If the current thread is being terminated, help out.
	 */
	if ((!cur_task->active) || (!cur_thread->active)) {
		thread_unlock(cur_thread);
		thread_unlock(thread);
		(void) splx(s);
		task_unlock(cur_task);
		thread_terminate(cur_thread);
		return KERN_FAILURE;
	}
    
	thread_unlock(cur_thread);
	task_unlock(cur_task);

	/*
	 *	Terminate victim thread.
	 */
	if (!thread->active) {
		/*
		 *	Someone else got there first.
		 */
		thread_unlock(thread);
		(void) splx(s);
		return KERN_FAILURE;
	}

	thread->active = FALSE;

	thread_unlock(thread);
	(void) splx(s);

#if	MACH_HOST
	/*
	 *	Reassign thread to default pset if needed.
	 */
	thread_freeze(thread);
	if (thread->processor_set != &default_pset) {
		thread_doassign(thread, &default_pset, FALSE);
	}
#endif	/* MACH_HOST */

	/*
	 *	Halt the victim at the clean point.
	 */
	(void) thread_halt(thread, TRUE);
#if	MACH_HOST
	thread_unfreeze(thread);
#endif	/* MACH_HOST */
	/*
	 *	Shut down the victims IPC and deallocate its
	 *	reference to itself.
	 */
	ipc_thread_terminate(thread);
	thread_deallocate(thread);
	return KERN_SUCCESS;
}

kern_return_t thread_terminate_release(
	thread_t thread,
	task_t task,
	mach_port_t thread_name,
	mach_port_t reply_port,
	vm_offset_t address,
	vm_size_t size)
{
	if (task == NULL)
		return KERN_INVALID_ARGUMENT;

	mach_port_deallocate(task->itk_space, thread_name);

	if (reply_port != MACH_PORT_NULL)
		mach_port_destroy(task->itk_space, reply_port);

	if ((address != 0) || (size != 0))
		vm_deallocate(task->map, address, size);

	return thread_terminate(thread);
}

/*
 *	thread_force_terminate:
 *
 *	Version of thread_terminate called by task_terminate.  thread is
 *	not the current thread.  task_terminate is the dominant operation,
 *	so we can force this thread to stop.
 */
void
thread_force_terminate(
	thread_t	thread)
{
	boolean_t	deallocate_here;
	spl_t s;

	ipc_thread_disable(thread);

#if	MACH_HOST
	/*
	 *	Reassign thread to default pset if needed.
	 */
	thread_freeze(thread);
	if (thread->processor_set != &default_pset)
		thread_doassign(thread, &default_pset, FALSE);
#endif	/* MACH_HOST */

	s = splsched();
	thread_lock(thread);
	deallocate_here = thread->active;
	thread->active = FALSE;
	thread_unlock(thread);
	(void) splx(s);

	(void) thread_halt(thread, TRUE);
	ipc_thread_terminate(thread);

#if	MACH_HOST
	thread_unfreeze(thread);
#endif	/* MACH_HOST */

	if (deallocate_here)
		thread_deallocate(thread);
}


/*
 *	Halt a thread at a clean point, leaving it suspended.
 *
 *	must_halt indicates whether thread must halt.
 *
 */
kern_return_t thread_halt(
	thread_t	thread,
	boolean_t		must_halt)
{
	thread_t	cur_thread = current_thread();
	kern_return_t	ret;
	spl_t	s;

	if (thread == cur_thread)
		panic("thread_halt: trying to halt current thread.");
	/*
	 *	If must_halt is FALSE, then a check must be made for
	 *	a cycle of halt operations.
	 */
	if (!must_halt) {
		/*
		 *	Grab both thread locks.
		 */
		s = splsched();
		if ((vm_offset_t)thread < (vm_offset_t)cur_thread) {
			thread_lock(thread);
			thread_lock(cur_thread);
		}
		else {
			thread_lock(cur_thread);
			thread_lock(thread);
		}

		/*
		 *	If target thread is already halted, grab a hold
		 *	on it and return.
		 */
		if (thread->state & TH_HALTED) {
			thread->suspend_count++;
			thread_unlock(cur_thread);
			thread_unlock(thread);
			(void) splx(s);
			return KERN_SUCCESS;
		}

		/*
		 *	If someone is trying to halt us, we have a potential
		 *	halt cycle.  Break the cycle by interrupting anyone
		 *	who is trying to halt us, and causing this operation
		 *	to fail; retry logic will only retry operations
		 *	that cannot deadlock.  (If must_halt is TRUE, this
		 *	operation can never cause a deadlock.)
		 */
		if (cur_thread->ast & AST_HALT) {
			thread_wakeup_with_result(TH_EV_WAKE_ACTIVE(cur_thread),
				THREAD_INTERRUPTED);
			thread_unlock(thread);
			thread_unlock(cur_thread);
			(void) splx(s);
			return KERN_FAILURE;
		}

		thread_unlock(cur_thread);
	
	}
	else {
		/*
		 *	Lock thread and check whether it is already halted.
		 */
		s = splsched();
		thread_lock(thread);
		if (thread->state & TH_HALTED) {
			thread->suspend_count++;
			thread_unlock(thread);
			(void) splx(s);
			return KERN_SUCCESS;
		}
	}

	/*
	 *	Suspend thread - inline version of thread_hold() because
	 *	thread is already locked.
	 */
	thread->suspend_count++;
	thread->state |= TH_SUSP;

	/*
	 *	If someone else is halting it, wait for that to complete.
	 *	Fail if wait interrupted and must_halt is false.
	 */
	while ((thread->ast & AST_HALT) && (!(thread->state & TH_HALTED))) {
		thread->wake_active = TRUE;
		thread_sleep(TH_EV_WAKE_ACTIVE(thread),
			simple_lock_addr(thread->lock), TRUE);

		if (thread->state & TH_HALTED) {
			(void) splx(s);
			return KERN_SUCCESS;
		}
		if ((current_thread()->wait_result != THREAD_AWAKENED)
		    && !(must_halt)) {
			(void) splx(s);
			thread_release(thread);
			return KERN_FAILURE;
		}
		thread_lock(thread);
	}

	/*
	 *	Otherwise, have to do it ourselves.
	 */
		
	thread_ast_set(thread, AST_HALT);

	while (TRUE) {
	  	/*
		 *	Wait for thread to stop.
		 */
		thread_unlock(thread);
		(void) splx(s);

		ret = thread_dowait(thread, must_halt);

		/*
		 *	If the dowait failed, so do we.  Drop AST_HALT, and
		 *	wake up anyone else who might be waiting for it.
		 */
		if (ret != KERN_SUCCESS) {
			s = splsched();
			thread_lock(thread);
			thread_ast_clear(thread, AST_HALT);
			thread_wakeup_with_result(TH_EV_WAKE_ACTIVE(thread),
				THREAD_INTERRUPTED);
			thread_unlock(thread);
			(void) splx(s);

			thread_release(thread);
			return ret;
		}

		/*
		 *	Clear any interruptible wait.
		 */
		clear_wait(thread, THREAD_INTERRUPTED, TRUE);

		/*
		 *	If the thread's at a clean point, we're done.
		 *	Don't need a lock because it really is stopped.
		 */
		if (thread->state & TH_HALTED) {
			return KERN_SUCCESS;
		}

		/*
		 *	If the thread is at a nice continuation,
		 *	or a continuation with a cleanup routine,
		 *	call the cleanup routine.
		 */
		if ((((thread->swap_func == mach_msg_continue) ||
		      (thread->swap_func == mach_msg_receive_continue)) &&
		     mach_msg_interrupt(thread)) ||
		    (thread->swap_func == thread_exception_return) ||
		    (thread->swap_func == thread_bootstrap_return)) {
			s = splsched();
			thread_lock(thread);
			thread->state |= TH_HALTED;
			thread_ast_clear(thread, AST_HALT);
			thread_unlock(thread);
			splx(s);

			return KERN_SUCCESS;
		}

		/*
		 *	Force the thread to stop at a clean
		 *	point, and arrange to wait for it.
		 *
		 *	Set it running, so it can notice.  Override
		 *	the suspend count.  We know that the thread
		 *	is suspended and not waiting.
		 *
		 *	Since the thread may hit an interruptible wait
		 *	before it reaches a clean point, we must force it
		 *	to wake us up when it does so.  This involves some
		 *	trickery:
		 *	  We mark the thread SUSPENDED so that thread_block
		 *	will suspend it and wake us up.
		 *	  We mark the thread RUNNING so that it will run.
		 *	  We mark the thread UN-INTERRUPTIBLE (!) so that
		 *	some other thread trying to halt or suspend it won't
		 *	take it off the run queue before it runs.  Since
		 *	dispatching a thread (the tail of thread_invoke) marks
		 *	the thread interruptible, it will stop at the next
		 *	context switch or interruptible wait.
		 */

		s = splsched();
		thread_lock(thread);
		if ((thread->state & TH_SCHED_STATE) != TH_SUSP)
			panic("thread_halt");
		thread->state |= TH_RUN | TH_UNINT;
		thread_setrun(thread, FALSE);

		/*
		 *	Continue loop and wait for thread to stop.
		 */
	}
}

void __attribute__((noreturn)) walking_zombie(void)
{
	panic("the zombie walks!");
}

/*
 *	Thread calls this routine on exit from the kernel when it
 *	notices a halt request.
 */
void	thread_halt_self(continuation_t continuation)
{
	thread_t	thread = current_thread();
	spl_t	s;

	if (thread->ast & AST_TERMINATE) {
		/*
		 *	Thread is terminating itself.  Shut
		 *	down IPC, then queue it up for the
		 *	reaper thread.
		 */
		ipc_thread_terminate(thread);

		thread_hold(thread);

		s = splsched();
		simple_lock(&reaper_lock);
		enqueue_tail(&reaper_queue, &(thread->links));
		simple_unlock(&reaper_lock);

		thread_lock(thread);
		thread->state |= TH_HALTED;
		thread_unlock(thread);
		(void) splx(s);

		thread_wakeup((event_t)&reaper_queue);
		counter(c_thread_halt_self_block++);
		thread_block(walking_zombie);
		/*NOTREACHED*/
	} else {
		/*
		 *	Thread was asked to halt - show that it
		 *	has done so.
		 */
		s = splsched();
		thread_lock(thread);
		thread->state |= TH_HALTED;
		thread_ast_clear(thread, AST_HALT);
		thread_unlock(thread);
		splx(s);
		counter(c_thread_halt_self_block++);
		thread_block(continuation);
		/*
		 *	thread_release resets TH_HALTED.
		 */
	}
}

/*
 *	thread_hold:
 *
 *	Suspend execution of the specified thread.
 *	This is a recursive-style suspension of the thread, a count of
 *	suspends is maintained.
 */
void thread_hold(
	thread_t	thread)
{
	spl_t			s;

	s = splsched();
	thread_lock(thread);
	thread->suspend_count++;
	thread->state |= TH_SUSP;
	thread_unlock(thread);
	(void) splx(s);
}

/*
 *	thread_dowait:
 *
 *	Wait for a thread to actually enter stopped state.
 *
 *	must_halt argument indicates if this may fail on interruption.
 *	This is FALSE only if called from thread_abort via thread_halt.
 */
kern_return_t
thread_dowait(
	thread_t		thread,
	boolean_t		must_halt)
{
	boolean_t		need_wakeup;
	kern_return_t		ret = KERN_SUCCESS;
	spl_t			s;

	if (thread == current_thread())
		panic("thread_dowait");

	/*
	 *	If a thread is not interruptible, it may not be suspended
	 *	until it becomes interruptible.  In this case, we wait for
	 *	the thread to stop itself, and indicate that we are waiting
	 *	for it to stop so that it can wake us up when it does stop.
	 *
	 *	If the thread is interruptible, we may be able to suspend
	 *	it immediately.  There are several cases:
	 *
	 *	1) The thread is already stopped (trivial)
	 *	2) The thread is runnable (marked RUN and on a run queue).
	 *	   We pull it off the run queue and mark it stopped.
	 *	3) The thread is running.  We wait for it to stop.
	 */

	need_wakeup = FALSE;
	s = splsched();
	thread_lock(thread);

	for (;;) {
	    switch (thread->state & TH_SCHED_STATE) {
		case			TH_SUSP:
		case	      TH_WAIT | TH_SUSP:
		    /*
		     *	Thread is already suspended, or sleeping in an
		     *	interruptible wait.  We win!
		     */
		    break;

		case TH_RUN	      | TH_SUSP:
		    /*
		     *	The thread is interruptible.  If we can pull
		     *	it off a runq, stop it here.
		     */
		    if (rem_runq(thread) != RUN_QUEUE_NULL) {
			thread->state &= ~TH_RUN;
			need_wakeup = thread->wake_active;
			thread->wake_active = FALSE;
			break;
		    }
#if	NCPUS > 1
		    /*
		     *	The thread must be running, so make its
		     *	processor execute ast_check().  This
		     *	should cause the thread to take an ast and
		     *	context switch to suspend for us.
		     */
		    cause_ast_check(thread->last_processor);
#endif	/* NCPUS > 1 */

		    /*
		     *	Fall through to wait for thread to stop.
		     */

		case TH_RUN	      | TH_SUSP | TH_UNINT:
		case TH_RUN | TH_WAIT | TH_SUSP:
		case TH_RUN | TH_WAIT | TH_SUSP | TH_UNINT:
		case	      TH_WAIT | TH_SUSP | TH_UNINT:
		    /*
		     *	Wait for the thread to stop, or sleep interruptibly
		     *	(thread_block will stop it in the latter case).
		     *	Check for failure if interrupted.
		     */
		    thread->wake_active = TRUE;
		    thread_sleep(TH_EV_WAKE_ACTIVE(thread),
				simple_lock_addr(thread->lock), TRUE);
		    thread_lock(thread);
		    if ((current_thread()->wait_result != THREAD_AWAKENED) &&
			    !must_halt) {
			ret = KERN_FAILURE;
			break;
		    }

		    /*
		     *	Repeat loop to check thread`s state.
		     */
		    continue;
	    }
	    /*
	     *	Thread is stopped at this point.
	     */
	    break;
	}

	thread_unlock(thread);
	(void) splx(s);

	if (need_wakeup)
	    thread_wakeup(TH_EV_WAKE_ACTIVE(thread));

	return ret;
}

void thread_release(
	thread_t	thread)
{
	spl_t			s;

	s = splsched();
	thread_lock(thread);
	if (--thread->suspend_count == 0) {
		thread->state &= ~(TH_SUSP | TH_HALTED);
		if ((thread->state & (TH_WAIT | TH_RUN)) == 0) {
			/* was only suspended */
			thread->state |= TH_RUN;
			thread_setrun(thread, TRUE);
		}
	}
	thread_unlock(thread);
	(void) splx(s);
}

kern_return_t thread_suspend(
	thread_t	thread)
{
	boolean_t		hold;
	spl_t			spl;

	if (thread == THREAD_NULL)
		return KERN_INVALID_ARGUMENT;

	hold = FALSE;
	spl = splsched();
	thread_lock(thread);
	/* Wait for thread to get interruptible */
	while (thread->state & TH_UNINT) {
		assert_wait(TH_EV_STATE(thread), TRUE);
		thread_unlock(thread);
		thread_block(thread_no_continuation);
		thread_lock(thread);
	}
	if (thread->user_stop_count++ == 0) {
		hold = TRUE;
		thread->suspend_count++;
		thread->state |= TH_SUSP;
	}
	thread_unlock(thread);
	(void) splx(spl);

	/*
	 *	Now  wait for the thread if necessary.
	 */
	if (hold) {
		if (thread == current_thread()) {
			/*
			 *	We want to call thread_block on our way out,
			 *	to stop running.
			 */
			spl = splsched();
			ast_on(cpu_number(), AST_BLOCK);
			(void) splx(spl);
		} else
			(void) thread_dowait(thread, TRUE);
	}
	return KERN_SUCCESS;
}


kern_return_t thread_resume(
	thread_t	thread)
{
	kern_return_t		ret;
	spl_t			s;

	if (thread == THREAD_NULL)
		return KERN_INVALID_ARGUMENT;

	ret = KERN_SUCCESS;

	s = splsched();
	thread_lock(thread);
	if (thread->user_stop_count > 0) {
	    if (--thread->user_stop_count == 0) {
		if (--thread->suspend_count == 0) {
		    thread->state &= ~(TH_SUSP | TH_HALTED);
		    if ((thread->state & (TH_WAIT | TH_RUN)) == 0) {
			    /* was only suspended */
			    thread->state |= TH_RUN;
			    thread_setrun(thread, TRUE);
		    }
		}
	    }
	}
	else {
		ret = KERN_FAILURE;
	}

	thread_unlock(thread);
	(void) splx(s);

	return ret;
}

/*
 *	Return thread's machine-dependent state.
 */
kern_return_t thread_get_state(
	thread_t		thread,
	int			flavor,
	thread_state_t		old_state,	/* pointer to OUT array */
	natural_t		*old_state_count)	/*IN/OUT*/
{
	kern_return_t		ret;

	if (thread == THREAD_NULL || thread == current_thread()) {
		return KERN_INVALID_ARGUMENT;
	}

	thread_hold(thread);
	(void) thread_dowait(thread, TRUE);

	ret = thread_getstatus(thread, flavor, old_state, old_state_count);

	thread_release(thread);
	return ret;
}

/*
 *	Change thread's machine-dependent state.
 */
kern_return_t thread_set_state(
	thread_t		thread,
	int			flavor,
	thread_state_t		new_state,
	natural_t		new_state_count)
{
	kern_return_t		ret;

	if (thread == THREAD_NULL || thread == current_thread()) {
		return KERN_INVALID_ARGUMENT;
	}

	thread_hold(thread);
	(void) thread_dowait(thread, TRUE);

	ret = thread_setstatus(thread, flavor, new_state, new_state_count);

	thread_release(thread);
	return ret;
}

kern_return_t thread_info(
	thread_t		thread,
	int			flavor,
	thread_info_t		thread_info_out,    /* pointer to OUT array */
	natural_t		*thread_info_count) /*IN/OUT*/
{
	int			state, flags;
	spl_t			s;

	if (thread == THREAD_NULL)
		return KERN_INVALID_ARGUMENT;

	if (flavor == THREAD_BASIC_INFO) {
	    thread_basic_info_t	basic_info;

	    /* Allow *thread_info_count to be one smaller than the
	       usual amount, because creation_time is a new member
	       that some callers might not know about. */

	    if (*thread_info_count < THREAD_BASIC_INFO_COUNT - 1) {
		return KERN_INVALID_ARGUMENT;
	    }

	    basic_info = (thread_basic_info_t) thread_info_out;

	    s = splsched();
	    thread_lock(thread);

	    /*
	     *	Update lazy-evaluated scheduler info because someone wants it.
	     */
	    if ((thread->state & TH_RUN) == 0 &&
		thread->sched_stamp != sched_tick)
		    update_priority(thread);

	    /* fill in info */

	    thread_read_times(thread,
			&basic_info->user_time,
			&basic_info->system_time);
	    basic_info->base_priority	= thread->priority;
	    basic_info->cur_priority	= thread->sched_pri;
	    read_time_stamp(&thread->creation_time,
			    &basic_info->creation_time);

	    /*
	     *	To calculate cpu_usage, first correct for timer rate,
	     *	then for 5/8 ageing.  The correction factor [3/5] is
	     *	(1/(5/8) - 1).
	     */
	    basic_info->cpu_usage = thread->cpu_usage /
					(TIMER_RATE/TH_USAGE_SCALE);
	    basic_info->cpu_usage = (basic_info->cpu_usage * 3) / 5;
#if	SIMPLE_CLOCK
	    /*
	     *	Clock drift compensation.
	     */
	    basic_info->cpu_usage =
		(basic_info->cpu_usage * 1000000)/sched_usec;
#endif	/* SIMPLE_CLOCK */

	    flags = 0;
	    if (thread->state & TH_SWAPPED)
		flags |= TH_FLAGS_SWAPPED;
	    if (thread->state & TH_IDLE)
		flags |= TH_FLAGS_IDLE;

	    if (thread->state & TH_HALTED)
		state = TH_STATE_HALTED;
	    else
	    if (thread->state & TH_RUN)
		state = TH_STATE_RUNNING;
	    else
	    if (thread->state & TH_UNINT)
		state = TH_STATE_UNINTERRUPTIBLE;
	    else
	    if (thread->state & TH_SUSP)
		state = TH_STATE_STOPPED;
	    else
	    if (thread->state & TH_WAIT)
		state = TH_STATE_WAITING;
	    else
		state = 0;		/* ? */

	    basic_info->run_state = state;
	    basic_info->flags = flags;
	    basic_info->suspend_count = thread->user_stop_count;
	    if (state == TH_STATE_RUNNING)
		basic_info->sleep_time = 0;
	    else
		basic_info->sleep_time = sched_tick - thread->sched_stamp;

	    thread_unlock(thread);
	    splx(s);

	    if (*thread_info_count > THREAD_BASIC_INFO_COUNT)
	      *thread_info_count = THREAD_BASIC_INFO_COUNT;
	    return KERN_SUCCESS;
	}
	else if (flavor == THREAD_SCHED_INFO) {
	    thread_sched_info_t	sched_info;

	    if (*thread_info_count < THREAD_SCHED_INFO_COUNT) {
		return KERN_INVALID_ARGUMENT;
	    }

	    sched_info = (thread_sched_info_t) thread_info_out;

	    s = splsched();
	    thread_lock(thread);

#if	MACH_FIXPRI
	    sched_info->policy = thread->policy;
	    if (thread->policy == POLICY_FIXEDPRI) {
		sched_info->data = (thread->sched_data * tick)/1000;
	    }
	    else {
		sched_info->data = 0;
	    }
#else	/* MACH_FIXPRI */
	    sched_info->policy = POLICY_TIMESHARE;
	    sched_info->data = 0;
#endif	/* MACH_FIXPRI */

	    sched_info->base_priority = thread->priority;
	    sched_info->max_priority = thread->max_priority;
	    sched_info->cur_priority = thread->sched_pri;
	    
	    sched_info->depressed = (thread->depress_priority >= 0);
	    sched_info->depress_priority = thread->depress_priority;

	    thread_unlock(thread);
	    splx(s);

	    *thread_info_count = THREAD_SCHED_INFO_COUNT;
	    return KERN_SUCCESS;
	}

	return KERN_INVALID_ARGUMENT;
}

kern_return_t	thread_abort(
	thread_t	thread)
{
	if (thread == THREAD_NULL || thread == current_thread()) {
		return KERN_INVALID_ARGUMENT;
	}

	/*
	 *
         *	clear it of an event wait 
         */
	evc_notify_abort(thread);

	/*
	 *	Try to force the thread to a clean point
	 *	If the halt operation fails return KERN_ABORTED.
	 *	ipc code will convert this to an ipc interrupted error code.
	 */
	if (thread_halt(thread, FALSE) != KERN_SUCCESS)
		return KERN_ABORTED;

	/*
	 *	If the thread was in an exception, abort that too.
	 */
	mach_msg_abort_rpc(thread);

	/*
	 *	Then set it going again.
	 */
	thread_release(thread);

	/*
	 *	Also abort any depression.
	 */
	if (thread->depress_priority != -1)
		thread_depress_abort(thread);

	return KERN_SUCCESS;
}

/*
 *	thread_start:
 *
 *	Start a thread at the specified routine.
 *	The thread must	be in a swapped state.
 */

void
thread_start(
	thread_t	thread,
	continuation_t	start)
{
	thread->swap_func = start;
}

/*
 *	kernel_thread:
 *
 *	Start up a kernel thread in the specified task.
 */

thread_t kernel_thread(
	task_t		task,
	continuation_t	start,
	void *		arg)
{
	kern_return_t	kr;
	thread_t	thread;

	kr = thread_create(task, &thread);
	if (kr != KERN_SUCCESS)
		return THREAD_NULL;

	/* release "extra" ref that thread_create gave us */
	thread_deallocate(thread);
	thread_start(thread, start);
	thread->ith_other = arg;

	/*
	 *	We ensure that the kernel thread starts with a stack.
	 *	The swapin mechanism might not be operational yet.
	 */
	thread_doswapin(thread);
	thread->max_priority = BASEPRI_SYSTEM;
	thread->priority = BASEPRI_SYSTEM;
	thread->sched_pri = BASEPRI_SYSTEM;
	(void) thread_resume(thread);
	return thread;
}

/*
 *	reaper_thread:
 *
 *	This kernel thread runs forever looking for threads to destroy
 *	(when they request that they be destroyed, of course).
 */
void __attribute__((noreturn)) reaper_thread_continue(void)
{
	for (;;) {
		thread_t thread;
		spl_t s;

		s = splsched();
		simple_lock(&reaper_lock);

		while ((thread = (thread_t) dequeue_head(&reaper_queue))
							!= THREAD_NULL) {
			simple_unlock(&reaper_lock);
			(void) splx(s);

			(void) thread_dowait(thread, TRUE);	/* may block */
			thread_deallocate(thread);		/* may block */

			s = splsched();
			simple_lock(&reaper_lock);
		}

		assert_wait((event_t) &reaper_queue, FALSE);
		simple_unlock(&reaper_lock);
		(void) splx(s);
		counter(c_reaper_thread_block++);
		thread_block(reaper_thread_continue);
	}
}

void reaper_thread(void)
{
	reaper_thread_continue();
	/*NOTREACHED*/
}

#if	MACH_HOST
/*
 *	thread_assign:
 *
 *	Change processor set assignment.
 *	Caller must hold an extra reference to the thread (if this is
 *	called directly from the ipc interface, this is an operation
 *	in progress reference).  Caller must hold no locks -- this may block.
 */

kern_return_t
thread_assign(
	thread_t	thread,
	processor_set_t	new_pset)
{
	if (thread == THREAD_NULL || new_pset == PROCESSOR_SET_NULL) {
		return KERN_INVALID_ARGUMENT;
	}

	thread_freeze(thread);
	thread_doassign(thread, new_pset, TRUE);

	return KERN_SUCCESS;
}

/*
 *	thread_freeze:
 *
 *	Freeze thread's assignment.  Prelude to assigning thread.
 *	Only one freeze may be held per thread.  
 */
void
thread_freeze(
	thread_t	thread)
{
	spl_t	s;
	/*
	 *	Freeze the assignment, deferring to a prior freeze.
	 */
	s = splsched();
	thread_lock(thread);
	while (thread->may_assign == FALSE) {
		thread->assign_active = TRUE;
		thread_sleep((event_t) &thread->assign_active,
			simple_lock_addr(thread->lock), FALSE);
		thread_lock(thread);
	}
	thread->may_assign = FALSE;
	thread_unlock(thread);
	(void) splx(s);

}

/*
 *	thread_unfreeze: release freeze on thread's assignment.
 */
void
thread_unfreeze(
	thread_t	thread)
{
	spl_t 	s;

	s = splsched();
	thread_lock(thread);
	thread->may_assign = TRUE;
	if (thread->assign_active) {
		thread->assign_active = FALSE;
		thread_wakeup((event_t)&thread->assign_active);
	}
	thread_unlock(thread);
	splx(s);
}

/*
 *	thread_doassign:
 *
 *	Actually do thread assignment.  thread_will_assign must have been
 *	called on the thread.  release_freeze argument indicates whether
 *	to release freeze on thread.
 */

void
thread_doassign(
	thread_t			thread,
	processor_set_t			new_pset,
	boolean_t			release_freeze)
{
	processor_set_t			pset;
	boolean_t			old_empty, new_empty;
	boolean_t			recompute_pri = FALSE;
	spl_t				s;
	
	/*
	 *	Check for silly no-op.
	 */
	pset = thread->processor_set;
	if (pset == new_pset) {
		if (release_freeze)
			thread_unfreeze(thread);
		return;
	}
	/*
	 *	Suspend the thread and stop it if it's not the current thread.
	 */
	thread_hold(thread);
	if (thread != current_thread())
		(void) thread_dowait(thread, TRUE);

	/*
	 *	Lock both psets now, use ordering to avoid deadlocks.
	 */
Restart:
	if ((vm_offset_t)pset < (vm_offset_t)new_pset) {
	    pset_lock(pset);
	    pset_lock(new_pset);
	}
	else {
	    pset_lock(new_pset);
	    pset_lock(pset);
	}

	/*
	 *	Check if new_pset is ok to assign to.  If not, reassign
	 *	to default_pset.
	 */
	if (!new_pset->active) {
	    pset_unlock(pset);
	    pset_unlock(new_pset);
	    new_pset = &default_pset;
	    goto Restart;
	}

	pset_reference(new_pset);

	/*
	 *	Grab the thread lock and move the thread.
	 *	Then drop the lock on the old pset and the thread's
	 *	reference to it.
	 */
	s = splsched();
	thread_lock(thread);

	thread_change_psets(thread, pset, new_pset);

	old_empty = pset->empty;
	new_empty = new_pset->empty;

	pset_unlock(pset);

	/*
	 *	Reset policy and priorities if needed.
	 */
#if	MACH_FIXPRI
	if (thread->policy & new_pset->policies == 0) {
	    thread->policy = POLICY_TIMESHARE;
	    recompute_pri = TRUE;
	}
#endif	/* MACH_FIXPRI */

	if (thread->max_priority < new_pset->max_priority) {
	    thread->max_priority = new_pset->max_priority;
	    if (thread->priority < thread->max_priority) {
		thread->priority = thread->max_priority;
		recompute_pri = TRUE;
	    }
	    else {
		if ((thread->depress_priority >= 0) &&
		    (thread->depress_priority < thread->max_priority)) {
			thread->depress_priority = thread->max_priority;
		}
	    }
	}

	pset_unlock(new_pset);

	if (recompute_pri)
		compute_priority(thread, TRUE);

	if (release_freeze) {
		thread->may_assign = TRUE;
		if (thread->assign_active) {
			thread->assign_active = FALSE;
			thread_wakeup((event_t)&thread->assign_active);
		}
	}

	thread_unlock(thread);
	splx(s);

	pset_deallocate(pset);

	/*
	 *	Figure out hold status of thread.  Threads assigned to empty
	 *	psets must be held.  Therefore:
	 *		If old pset was empty release its hold.
	 *		Release our hold from above unless new pset is empty.
	 */

	if (old_empty)
		thread_release(thread);
	if (!new_empty)
		thread_release(thread);

	/*
	 *	If current_thread is assigned, context switch to force
	 *	assignment to happen.  This also causes hold to take
	 *	effect if the new pset is empty.
	 */
	if (thread == current_thread()) {
		s = splsched();
		ast_on(cpu_number(), AST_BLOCK);
		(void) splx(s);
	}
}
#else	/* MACH_HOST */
kern_return_t
thread_assign(
	thread_t	thread,
	processor_set_t	new_pset)
{
	return KERN_FAILURE;
}
#endif	/* MACH_HOST */

/*
 *	thread_assign_default:
 *
 *	Special version of thread_assign for assigning threads to default
 *	processor set.
 */
kern_return_t
thread_assign_default(
	thread_t	thread)
{
	return thread_assign(thread, &default_pset);
}

/*
 *	thread_get_assignment
 *
 *	Return current assignment for this thread.
 */	    
kern_return_t thread_get_assignment(
	thread_t	thread,
	processor_set_t	*pset)
{
	if (thread == THREAD_NULL)
		return KERN_INVALID_ARGUMENT;

	*pset = thread->processor_set;
	pset_reference(*pset);
	return KERN_SUCCESS;
}

/*
 *	thread_priority:
 *
 *	Set priority (and possibly max priority) for thread.
 */
kern_return_t
thread_priority(
	thread_t	thread,
	int		priority,
	boolean_t	set_max)
{
    spl_t		s;
    kern_return_t	ret = KERN_SUCCESS;

    if ((thread == THREAD_NULL) || invalid_pri(priority))
	return KERN_INVALID_ARGUMENT;

    s = splsched();
    thread_lock(thread);

    /*
     *	Check for violation of max priority
     */
    if (priority < thread->max_priority) {
	ret = KERN_FAILURE;
    }
    else {
	/*
	 *	Set priorities.  If a depression is in progress,
	 *	change the priority to restore.
	 */
	if (thread->depress_priority >= 0) {
	    thread->depress_priority = priority;
	}
	else {
	    thread->priority = priority;
	    compute_priority(thread, TRUE);
	}

	if (set_max)
	    thread->max_priority = priority;
    }
    thread_unlock(thread);
    (void) splx(s);

    return ret;
}

/*
 *	thread_set_own_priority:
 *
 *	Internal use only; sets the priority of the calling thread.
 *	Will adjust max_priority if necessary.
 */
void
thread_set_own_priority(
	int	priority)
{
    spl_t	s;
    thread_t	thread = current_thread();

    s = splsched();
    thread_lock(thread);

    if (priority < thread->max_priority)
	thread->max_priority = priority;
    thread->priority = priority;
    compute_priority(thread, TRUE);

    thread_unlock(thread);
    (void) splx(s);
}

/*
 *	thread_max_priority:
 *
 *	Reset the max priority for a thread.
 */
kern_return_t
thread_max_priority(
	thread_t	thread,
	processor_set_t	pset,
	int		max_priority)
{
    spl_t		s;
    kern_return_t	ret = KERN_SUCCESS;

    if ((thread == THREAD_NULL) || (pset == PROCESSOR_SET_NULL) ||
    	invalid_pri(max_priority))
	    return KERN_INVALID_ARGUMENT;

    s = splsched();
    thread_lock(thread);

#if	MACH_HOST
    /*
     *	Check for wrong processor set.
     */
    if (pset != thread->processor_set) {
	ret = KERN_FAILURE;
    }
    else {
#endif	/* MACH_HOST */
	thread->max_priority = max_priority;

	/*
	 *	Reset priority if it violates new max priority
	 */
	if (max_priority > thread->priority) {
	    thread->priority = max_priority;

	    compute_priority(thread, TRUE);
	}
	else {
	    if (thread->depress_priority >= 0 &&
		max_priority > thread->depress_priority)
		    thread->depress_priority = max_priority;
	    }
#if	MACH_HOST
    }
#endif	/* MACH_HOST */

    thread_unlock(thread);
    (void) splx(s);

    return ret;
}

/*
 *	thread_policy:
 *
 *	Set scheduling policy for thread.
 */
kern_return_t
thread_policy(
	thread_t	thread,
	int		policy,
	int		data)
{
#if	MACH_FIXPRI
	kern_return_t	ret = KERN_SUCCESS;
	int		temp;
	spl_t		s;
#endif	/* MACH_FIXPRI */

	if ((thread == THREAD_NULL) || invalid_policy(policy))
		return KERN_INVALID_ARGUMENT;

#if	MACH_FIXPRI
	s = splsched();
	thread_lock(thread);

	/*
	 *	Check if changing policy.
	 */
	if (policy == thread->policy) {
	    /*
	     *	Just changing data.  This is meaningless for
	     *	timesharing, quantum for fixed priority (but
	     *	has no effect until current quantum runs out).
	     */
	    if (policy == POLICY_FIXEDPRI) {
		temp = data * 1000;
		if (temp % tick)
			temp += tick;
		thread->sched_data = temp/tick;
	    }
	}
	else {
	    /*
	     *	Changing policy.  Check if new policy is allowed.
	     */
	    if ((thread->processor_set->policies & policy) == 0) {
		    ret = KERN_FAILURE;
	    }
	    else {
		/*
		 *	Changing policy.  Save data and calculate new
		 *	priority.
		 */
		thread->policy = policy;
		if (policy == POLICY_FIXEDPRI) {
			temp = data * 1000;
			if (temp % tick)
				temp += tick;
			thread->sched_data = temp/tick;
		}
		compute_priority(thread, TRUE);
	    }
	}
	thread_unlock(thread);
	(void) splx(s);

	return ret;
#else	/* MACH_FIXPRI */
	if (policy == POLICY_TIMESHARE)
		return KERN_SUCCESS;
	else
		return KERN_FAILURE;
#endif	/* MACH_FIXPRI */
}

/*
 *	thread_wire:
 *
 *	Specify that the target thread must always be able
 *	to run and to allocate memory.
 */
kern_return_t
thread_wire(
	host_t		host,
	thread_t	thread,
	boolean_t	wired)
{
	spl_t		s;

	if (host == HOST_NULL)
	    return KERN_INVALID_ARGUMENT;

	if (thread == THREAD_NULL)
	    return KERN_INVALID_ARGUMENT;

	/*
	 * This implementation only works for the current thread.
	 * See stack_privilege.
	 */
	if (thread != current_thread())
	    return KERN_INVALID_ARGUMENT;

	s = splsched();
	thread_lock(thread);

	if (wired) {
	    thread->vm_privilege = TRUE;
	    stack_privilege(thread);
	}
	else {
	    thread->vm_privilege = FALSE;
/*XXX	    stack_unprivilege(thread); */
	    thread->stack_privilege = 0;
	}

	thread_unlock(thread);
	splx(s);

	return KERN_SUCCESS;
}

/*
 *	thread_collect_scan:
 *
 *	Attempt to free resources owned by threads.
 *	pcb_collect doesn't do anything yet.
 */

void thread_collect_scan(void)
{
	register thread_t	thread, prev_thread;
	processor_set_t		pset, prev_pset;

	prev_thread = THREAD_NULL;
	prev_pset = PROCESSOR_SET_NULL;

	lock_all_psets();
	queue_iterate(&all_psets, pset, processor_set_t, all_psets) {
		pset_lock(pset);
		queue_iterate(&pset->threads, thread, thread_t, pset_threads) {
			spl_t	s = splsched();
			thread_lock(thread);

			/*
			 *	Only collect threads which are
			 *	not runnable and are swapped.
			 */

			if ((thread->state & (TH_RUN|TH_SWAPPED))
							== TH_SWAPPED) {
				thread->ref_count++;
				thread_unlock(thread);
				(void) splx(s);
				pset->ref_count++;
				pset_unlock(pset);
				unlock_all_psets();

				pcb_collect(thread);

				if (prev_thread != THREAD_NULL)
					thread_deallocate(prev_thread);
				prev_thread = thread;

				if (prev_pset != PROCESSOR_SET_NULL)
					pset_deallocate(prev_pset);
				prev_pset = pset;

				lock_all_psets();
				pset_lock(pset);
			} else {
				thread_unlock(thread);
				(void) splx(s);
			}
		}
		pset_unlock(pset);
	}
	unlock_all_psets();

	if (prev_thread != THREAD_NULL)
		thread_deallocate(prev_thread);
	if (prev_pset != PROCESSOR_SET_NULL)
		pset_deallocate(prev_pset);
}

boolean_t thread_collect_allowed = TRUE;
unsigned thread_collect_last_tick = 0;
unsigned thread_collect_max_rate = 0;		/* in ticks */

/*
 *	consider_thread_collect:
 *
 *	Called by the pageout daemon when the system needs more free pages.
 */

void consider_thread_collect(void)
{
	/*
	 *	By default, don't attempt thread collection more frequently
	 *	than once a second.
	 */

	if (thread_collect_max_rate == 0)
		thread_collect_max_rate = hz;

	if (thread_collect_allowed &&
	    (sched_tick >
	     (thread_collect_last_tick + thread_collect_max_rate))) {
		thread_collect_last_tick = sched_tick;
		thread_collect_scan();
	}
}

#if	MACH_DEBUG

vm_size_t stack_usage(
	vm_offset_t stack)
{
	int i;

	for (i = 0; i < KERNEL_STACK_SIZE/sizeof(unsigned int); i++)
	    if (((unsigned int *)stack)[i] != STACK_MARKER)
		break;

	return KERNEL_STACK_SIZE - i * sizeof(unsigned int);
}

/*
 *	Machine-dependent code should call stack_init
 *	before doing its own initialization of the stack.
 */

void stack_init(
	vm_offset_t stack)
{
	if (stack_check_usage) {
	    int i;

	    for (i = 0; i < KERNEL_STACK_SIZE/sizeof(unsigned int); i++)
		((unsigned int *)stack)[i] = STACK_MARKER;
	}
}

/*
 *	Machine-dependent code should call stack_finalize
 *	before releasing the stack memory.
 */

void stack_finalize(
	vm_offset_t stack)
{
	if (stack_check_usage) {
	    vm_size_t used = stack_usage(stack);

	    simple_lock(&stack_usage_lock);
	    if (used > stack_max_usage)
		stack_max_usage = used;
	    simple_unlock(&stack_usage_lock);
	}
}

kern_return_t host_stack_usage(
	host_t		host,
	vm_size_t	*reservedp,
	unsigned int	*totalp,
	vm_size_t	*spacep,
	vm_size_t	*residentp,
	vm_size_t	*maxusagep,
	vm_offset_t	*maxstackp)
{
	natural_t total;
	vm_size_t maxusage;

	if (host == HOST_NULL)
		return KERN_INVALID_HOST;

	total = 0;	/* XXX */

	simple_lock(&stack_usage_lock);
	maxusage = stack_max_usage;
	simple_unlock(&stack_usage_lock);

	*reservedp = 0;
	*totalp = total;
	*spacep = *residentp = total * round_page(KERNEL_STACK_SIZE);
	*maxusagep = maxusage;
	*maxstackp = 0;
	return KERN_SUCCESS;
}

kern_return_t processor_set_stack_usage(
	processor_set_t	pset,
	unsigned int	*totalp,
	vm_size_t	*spacep,
	vm_size_t	*residentp,
	vm_size_t	*maxusagep,
	vm_offset_t	*maxstackp)
{
	unsigned int total;
	vm_size_t maxusage;
	vm_offset_t maxstack;

	thread_t *threads;
	thread_t tmp_thread;

	unsigned int actual;	/* this many things */
	unsigned int i;

	vm_size_t size, size_needed;
	vm_offset_t addr;

	if (pset == PROCESSOR_SET_NULL)
		return KERN_INVALID_ARGUMENT;

	size = 0; addr = 0;

	for (;;) {
		pset_lock(pset);
		if (!pset->active) {
			pset_unlock(pset);
			return KERN_INVALID_ARGUMENT;
		}

		actual = pset->thread_count;

		/* do we have the memory we need? */

		size_needed = actual * sizeof(thread_t);
		if (size_needed <= size)
			break;

		/* unlock the pset and allocate more memory */
		pset_unlock(pset);

		if (size != 0)
			kfree(addr, size);

		assert(size_needed > 0);
		size = size_needed;

		addr = kalloc(size);
		if (addr == 0)
			return KERN_RESOURCE_SHORTAGE;
	}

	/* OK, have memory and the processor_set is locked & active */

	threads = (thread_t *) addr;
	for (i = 0, tmp_thread = (thread_t) queue_first(&pset->threads);
	     i < actual;
	     i++,
	     tmp_thread = (thread_t) queue_next(&tmp_thread->pset_threads)) {
		thread_reference(tmp_thread);
		threads[i] = tmp_thread;
	}
	assert(queue_end(&pset->threads, (queue_entry_t) tmp_thread));

	/* can unlock processor set now that we have the thread refs */
	pset_unlock(pset);

	/* calculate maxusage and free thread references */

	total = 0;
	maxusage = 0;
	maxstack = 0;
	for (i = 0; i < actual; i++) {
		thread_t thread = threads[i];
		vm_offset_t stack = 0;

		/*
		 *	thread->kernel_stack is only accurate if the
		 *	thread isn't swapped and is not executing.
		 *
		 *	Of course, we don't have the appropriate locks
		 *	for these shenanigans.
		 */

		if ((thread->state & TH_SWAPPED) == 0) {
			int cpu;

			stack = thread->kernel_stack;

			for (cpu = 0; cpu < NCPUS; cpu++)
				if (active_threads[cpu] == thread) {
					stack = active_stacks[cpu];
					break;
				}
		}

		if (stack != 0) {
			total++;

			if (stack_check_usage) {
				vm_size_t usage = stack_usage(stack);

				if (usage > maxusage) {
					maxusage = usage;
					maxstack = (vm_offset_t) thread;
				}
			}
		}

		thread_deallocate(thread);
	}

	if (size != 0)
		kfree(addr, size);

	*totalp = total;
	*residentp = *spacep = total * round_page(KERNEL_STACK_SIZE);
	*maxusagep = maxusage;
	*maxstackp = maxstack;
	return KERN_SUCCESS;
}

/*
 *	Useful in the debugger:
 */
void
thread_stats(void)
{
	thread_t thread;
	int total = 0, rpcreply = 0;

	queue_iterate(&default_pset.threads, thread, thread_t, pset_threads) {
		total++;
		if (thread->ith_rpc_reply != IP_NULL)
			rpcreply++;
	}

	printf("%d total threads.\n", total);
	printf("%d using rpc_reply.\n", rpcreply);
}
#endif	/* MACH_DEBUG */