summaryrefslogtreecommitdiffstats
path: root/arch/s390/kernel/perf_cpum_sf.c
blob: bd4bbf61aaf368cba69d27edb2cd80dfac014493 (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
/*
 * Performance event support for the System z CPU-measurement Sampling Facility
 *
 * Copyright IBM Corp. 2013
 * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License (version 2 only)
 * as published by the Free Software Foundation.
 */
#define KMSG_COMPONENT	"cpum_sf"
#define pr_fmt(fmt)	KMSG_COMPONENT ": " fmt

#include <linux/kernel.h>
#include <linux/kernel_stat.h>
#include <linux/perf_event.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/moduleparam.h>
#include <asm/cpu_mf.h>
#include <asm/irq.h>
#include <asm/debug.h>
#include <asm/timex.h>

/* Minimum number of sample-data-block-tables:
 * At least one table is required for the sampling buffer structure.
 * A single table contains up to 511 pointers to sample-data-blocks.
 */
#define CPUM_SF_MIN_SDBT	1

/* Number of sample-data-blocks per sample-data-block-table (SDBT):
 * A table contains SDB pointers (8 bytes) and one table-link entry
 * that points to the origin of the next SDBT.
 */
#define CPUM_SF_SDB_PER_TABLE	((PAGE_SIZE - 8) / 8)

/* Maximum page offset for an SDBT table-link entry:
 * If this page offset is reached, a table-link entry to the next SDBT
 * must be added.
 */
#define CPUM_SF_SDBT_TL_OFFSET	(CPUM_SF_SDB_PER_TABLE * 8)
static inline int require_table_link(const void *sdbt)
{
	return ((unsigned long) sdbt & ~PAGE_MASK) == CPUM_SF_SDBT_TL_OFFSET;
}

/* Minimum and maximum sampling buffer sizes:
 *
 * This number represents the maximum size of the sampling buffer taking
 * the number of sample-data-block-tables into account.  Note that these
 * numbers apply to the basic-sampling function only.
 * The maximum number of SDBs is increased by CPUM_SF_SDB_DIAG_FACTOR if
 * the diagnostic-sampling function is active.
 *
 * Sampling buffer size		Buffer characteristics
 * ---------------------------------------------------
 *	 64KB		    ==	  16 pages (4KB per page)
 *				   1 page  for SDB-tables
 *				  15 pages for SDBs
 *
 *  32MB		    ==	8192 pages (4KB per page)
 *				  16 pages for SDB-tables
 *				8176 pages for SDBs
 */
static unsigned long __read_mostly CPUM_SF_MIN_SDB = 15;
static unsigned long __read_mostly CPUM_SF_MAX_SDB = 8176;
static unsigned long __read_mostly CPUM_SF_SDB_DIAG_FACTOR = 1;

struct sf_buffer {
	unsigned long	 *sdbt;	    /* Sample-data-block-table origin */
	/* buffer characteristics (required for buffer increments) */
	unsigned long  num_sdb;	    /* Number of sample-data-blocks */
	unsigned long num_sdbt;	    /* Number of sample-data-block-tables */
	unsigned long	 *tail;	    /* last sample-data-block-table */
};

struct cpu_hw_sf {
	/* CPU-measurement sampling information block */
	struct hws_qsi_info_block qsi;
	/* CPU-measurement sampling control block */
	struct hws_lsctl_request_block lsctl;
	struct sf_buffer sfb;	    /* Sampling buffer */
	unsigned int flags;	    /* Status flags */
	struct perf_event *event;   /* Scheduled perf event */
};
static DEFINE_PER_CPU(struct cpu_hw_sf, cpu_hw_sf);

/* Debug feature */
static debug_info_t *sfdbg;

/*
 * sf_disable() - Switch off sampling facility
 */
static int sf_disable(void)
{
	struct hws_lsctl_request_block sreq;

	memset(&sreq, 0, sizeof(sreq));
	return lsctl(&sreq);
}

/*
 * sf_buffer_available() - Check for an allocated sampling buffer
 */
static int sf_buffer_available(struct cpu_hw_sf *cpuhw)
{
	return !!cpuhw->sfb.sdbt;
}

/*
 * deallocate sampling facility buffer
 */
static void free_sampling_buffer(struct sf_buffer *sfb)
{
	unsigned long *sdbt, *curr;

	if (!sfb->sdbt)
		return;

	sdbt = sfb->sdbt;
	curr = sdbt;

	/* Free the SDBT after all SDBs are processed... */
	while (1) {
		if (!*curr || !sdbt)
			break;

		/* Process table-link entries */
		if (is_link_entry(curr)) {
			curr = get_next_sdbt(curr);
			if (sdbt)
				free_page((unsigned long) sdbt);

			/* If the origin is reached, sampling buffer is freed */
			if (curr == sfb->sdbt)
				break;
			else
				sdbt = curr;
		} else {
			/* Process SDB pointer */
			if (*curr) {
				free_page(*curr);
				curr++;
			}
		}
	}

	debug_sprintf_event(sfdbg, 5,
			    "free_sampling_buffer: freed sdbt=%p\n", sfb->sdbt);
	memset(sfb, 0, sizeof(*sfb));
}

static int alloc_sample_data_block(unsigned long *sdbt, gfp_t gfp_flags)
{
	unsigned long sdb, *trailer;

	/* Allocate and initialize sample-data-block */
	sdb = get_zeroed_page(gfp_flags);
	if (!sdb)
		return -ENOMEM;
	trailer = trailer_entry_ptr(sdb);
	*trailer = SDB_TE_ALERT_REQ_MASK;

	/* Link SDB into the sample-data-block-table */
	*sdbt = sdb;

	return 0;
}

/*
 * realloc_sampling_buffer() - extend sampler memory
 *
 * Allocates new sample-data-blocks and adds them to the specified sampling
 * buffer memory.
 *
 * Important: This modifies the sampling buffer and must be called when the
 *	      sampling facility is disabled.
 *
 * Returns zero on success, non-zero otherwise.
 */
static int realloc_sampling_buffer(struct sf_buffer *sfb,
				   unsigned long num_sdb, gfp_t gfp_flags)
{
	int i, rc;
	unsigned long *new, *tail;

	if (!sfb->sdbt || !sfb->tail)
		return -EINVAL;

	if (!is_link_entry(sfb->tail))
		return -EINVAL;

	/* Append to the existing sampling buffer, overwriting the table-link
	 * register.
	 * The tail variables always points to the "tail" (last and table-link)
	 * entry in an SDB-table.
	 */
	tail = sfb->tail;

	/* Do a sanity check whether the table-link entry points to
	 * the sampling buffer origin.
	 */
	if (sfb->sdbt != get_next_sdbt(tail)) {
		debug_sprintf_event(sfdbg, 3, "realloc_sampling_buffer: "
				    "sampling buffer is not linked: origin=%p"
				    "tail=%p\n",
				    (void *) sfb->sdbt, (void *) tail);
		return -EINVAL;
	}

	/* Allocate remaining SDBs */
	rc = 0;
	for (i = 0; i < num_sdb; i++) {
		/* Allocate a new SDB-table if it is full. */
		if (require_table_link(tail)) {
			new = (unsigned long *) get_zeroed_page(gfp_flags);
			if (!new) {
				rc = -ENOMEM;
				break;
			}
			sfb->num_sdbt++;
			/* Link current page to tail of chain */
			*tail = (unsigned long)(void *) new + 1;
			tail = new;
		}

		/* Allocate a new sample-data-block.
		 * If there is not enough memory, stop the realloc process
		 * and simply use what was allocated.  If this is a temporary
		 * issue, a new realloc call (if required) might succeed.
		 */
		rc = alloc_sample_data_block(tail, gfp_flags);
		if (rc)
			break;
		sfb->num_sdb++;
		tail++;
	}

	/* Link sampling buffer to its origin */
	*tail = (unsigned long) sfb->sdbt + 1;
	sfb->tail = tail;

	debug_sprintf_event(sfdbg, 4, "realloc_sampling_buffer: new buffer"
			    " settings: sdbt=%lu sdb=%lu\n",
			    sfb->num_sdbt, sfb->num_sdb);
	return rc;
}

/*
 * allocate_sampling_buffer() - allocate sampler memory
 *
 * Allocates and initializes a sampling buffer structure using the
 * specified number of sample-data-blocks (SDB).  For each allocation,
 * a 4K page is used.  The number of sample-data-block-tables (SDBT)
 * are calculated from SDBs.
 * Also set the ALERT_REQ mask in each SDBs trailer.
 *
 * Returns zero on success, non-zero otherwise.
 */
static int alloc_sampling_buffer(struct sf_buffer *sfb, unsigned long num_sdb)
{
	int rc;

	if (sfb->sdbt)
		return -EINVAL;

	/* Allocate the sample-data-block-table origin */
	sfb->sdbt = (unsigned long *) get_zeroed_page(GFP_KERNEL);
	if (!sfb->sdbt)
		return -ENOMEM;
	sfb->num_sdb = 0;
	sfb->num_sdbt = 1;

	/* Link the table origin to point to itself to prepare for
	 * realloc_sampling_buffer() invocation.
	 */
	sfb->tail = sfb->sdbt;
	*sfb->tail = (unsigned long)(void *) sfb->sdbt + 1;

	/* Allocate requested number of sample-data-blocks */
	rc = realloc_sampling_buffer(sfb, num_sdb, GFP_KERNEL);
	if (rc) {
		free_sampling_buffer(sfb);
		debug_sprintf_event(sfdbg, 4, "alloc_sampling_buffer: "
			"realloc_sampling_buffer failed with rc=%i\n", rc);
	} else
		debug_sprintf_event(sfdbg, 4,
			"alloc_sampling_buffer: tear=%p dear=%p\n",
			sfb->sdbt, (void *) *sfb->sdbt);
	return rc;
}

static void sfb_set_limits(unsigned long min, unsigned long max)
{
	struct hws_qsi_info_block si;

	CPUM_SF_MIN_SDB = min;
	CPUM_SF_MAX_SDB = max;

	memset(&si, 0, sizeof(si));
	if (!qsi(&si))
		CPUM_SF_SDB_DIAG_FACTOR = DIV_ROUND_UP(si.dsdes, si.bsdes);
}

static unsigned long sfb_max_limit(struct hw_perf_event *hwc)
{
	return SAMPL_DIAG_MODE(hwc) ? CPUM_SF_MAX_SDB * CPUM_SF_SDB_DIAG_FACTOR
				    : CPUM_SF_MAX_SDB;
}

static unsigned long sfb_pending_allocs(struct sf_buffer *sfb,
					struct hw_perf_event *hwc)
{
	if (!sfb->sdbt)
		return SFB_ALLOC_REG(hwc);
	if (SFB_ALLOC_REG(hwc) > sfb->num_sdb)
		return SFB_ALLOC_REG(hwc) - sfb->num_sdb;
	return 0;
}

static int sfb_has_pending_allocs(struct sf_buffer *sfb,
				   struct hw_perf_event *hwc)
{
	return sfb_pending_allocs(sfb, hwc) > 0;
}

static void sfb_account_allocs(unsigned long num, struct hw_perf_event *hwc)
{
	/* Limit the number of SDBs to not exceed the maximum */
	num = min_t(unsigned long, num, sfb_max_limit(hwc) - SFB_ALLOC_REG(hwc));
	if (num)
		SFB_ALLOC_REG(hwc) += num;
}

static void sfb_init_allocs(unsigned long num, struct hw_perf_event *hwc)
{
	SFB_ALLOC_REG(hwc) = 0;
	sfb_account_allocs(num, hwc);
}

static size_t event_sample_size(struct hw_perf_event *hwc)
{
	struct sf_raw_sample *sfr = (struct sf_raw_sample *) RAWSAMPLE_REG(hwc);
	size_t sample_size;

	/* The sample size depends on the sampling function: The basic-sampling
	 * function must be always enabled, diagnostic-sampling function is
	 * optional.
	 */
	sample_size = sfr->bsdes;
	if (SAMPL_DIAG_MODE(hwc))
		sample_size += sfr->dsdes;

	return sample_size;
}

static void deallocate_buffers(struct cpu_hw_sf *cpuhw)
{
	if (cpuhw->sfb.sdbt)
		free_sampling_buffer(&cpuhw->sfb);
}

static int allocate_buffers(struct cpu_hw_sf *cpuhw, struct hw_perf_event *hwc)
{
	unsigned long n_sdb, freq, factor;
	size_t sfr_size, sample_size;
	struct sf_raw_sample *sfr;

	/* Allocate raw sample buffer
	 *
	 *    The raw sample buffer is used to temporarily store sampling data
	 *    entries for perf raw sample processing.  The buffer size mainly
	 *    depends on the size of diagnostic-sampling data entries which is
	 *    machine-specific.  The exact size calculation includes:
	 *	1. The first 4 bytes of diagnostic-sampling data entries are
	 *	   already reflected in the sf_raw_sample structure.  Subtract
	 *	   these bytes.
	 *	2. The perf raw sample data must be 8-byte aligned (u64) and
	 *	   perf's internal data size must be considered too.  So add
	 *	   an additional u32 for correct alignment and subtract before
	 *	   allocating the buffer.
	 *	3. Store the raw sample buffer pointer in the perf event
	 *	   hardware structure.
	 */
	sfr_size = ALIGN((sizeof(*sfr) - sizeof(sfr->diag) + cpuhw->qsi.dsdes) +
			 sizeof(u32), sizeof(u64));
	sfr_size -= sizeof(u32);
	sfr = kzalloc(sfr_size, GFP_KERNEL);
	if (!sfr)
		return -ENOMEM;
	sfr->size = sfr_size;
	sfr->bsdes = cpuhw->qsi.bsdes;
	sfr->dsdes = cpuhw->qsi.dsdes;
	RAWSAMPLE_REG(hwc) = (unsigned long) sfr;

	/* Calculate sampling buffers using 4K pages
	 *
	 *    1. Determine the sample data size which depends on the used
	 *	 sampling functions, for example, basic-sampling or
	 *	 basic-sampling with diagnostic-sampling.
	 *
	 *    2. Use the sampling frequency as input.  The sampling buffer is
	 *	 designed for almost one second.  This can be adjusted through
	 *	 the "factor" variable.
	 *	 In any case, alloc_sampling_buffer() sets the Alert Request
	 *	 Control indicator to trigger a measurement-alert to harvest
	 *	 sample-data-blocks (sdb).
	 *
	 *    3. Compute the number of sample-data-blocks and ensure a minimum
	 *	 of CPUM_SF_MIN_SDB.  Also ensure the upper limit does not
	 *	 exceed a "calculated" maximum.  The symbolic maximum is
	 *	 designed for basic-sampling only and needs to be increased if
	 *	 diagnostic-sampling is active.
	 *	 See also the remarks for these symbolic constants.
	 *
	 *    4. Compute the number of sample-data-block-tables (SDBT) and
	 *	 ensure a minimum of CPUM_SF_MIN_SDBT (one table can manage up
	 *	 to 511 SDBs).
	 */
	sample_size = event_sample_size(hwc);
	freq = sample_rate_to_freq(&cpuhw->qsi, SAMPL_RATE(hwc));
	factor = 1;
	n_sdb = DIV_ROUND_UP(freq, factor * ((PAGE_SIZE-64) / sample_size));
	if (n_sdb < CPUM_SF_MIN_SDB)
		n_sdb = CPUM_SF_MIN_SDB;

	/* If there is already a sampling buffer allocated, it is very likely
	 * that the sampling facility is enabled too.  If the event to be
	 * initialized requires a greater sampling buffer, the allocation must
	 * be postponed.  Changing the sampling buffer requires the sampling
	 * facility to be in the disabled state.  So, account the number of
	 * required SDBs and let cpumsf_pmu_enable() resize the buffer just
	 * before the event is started.
	 */
	sfb_init_allocs(n_sdb, hwc);
	if (sf_buffer_available(cpuhw))
		return 0;

	debug_sprintf_event(sfdbg, 3,
			    "allocate_buffers: rate=%lu f=%lu sdb=%lu/%lu"
			    " sample_size=%lu cpuhw=%p\n",
			    SAMPL_RATE(hwc), freq, n_sdb, sfb_max_limit(hwc),
			    sample_size, cpuhw);

	return alloc_sampling_buffer(&cpuhw->sfb,
				     sfb_pending_allocs(&cpuhw->sfb, hwc));
}

static unsigned long min_percent(unsigned int percent, unsigned long base,
				 unsigned long min)
{
	return min_t(unsigned long, min, DIV_ROUND_UP(percent * base, 100));
}

static unsigned long compute_sfb_extent(unsigned long ratio, unsigned long base)
{
	/* Use a percentage-based approach to extend the sampling facility
	 * buffer.  Accept up to 5% sample data loss.
	 * Vary the extents between 1% to 5% of the current number of
	 * sample-data-blocks.
	 */
	if (ratio <= 5)
		return 0;
	if (ratio <= 25)
		return min_percent(1, base, 1);
	if (ratio <= 50)
		return min_percent(1, base, 1);
	if (ratio <= 75)
		return min_percent(2, base, 2);
	if (ratio <= 100)
		return min_percent(3, base, 3);
	if (ratio <= 250)
		return min_percent(4, base, 4);

	return min_percent(5, base, 8);
}

static void sfb_account_overflows(struct cpu_hw_sf *cpuhw,
				  struct hw_perf_event *hwc)
{
	unsigned long ratio, num;

	if (!OVERFLOW_REG(hwc))
		return;

	/* The sample_overflow contains the average number of sample data
	 * that has been lost because sample-data-blocks were full.
	 *
	 * Calculate the total number of sample data entries that has been
	 * discarded.  Then calculate the ratio of lost samples to total samples
	 * per second in percent.
	 */
	ratio = DIV_ROUND_UP(100 * OVERFLOW_REG(hwc) * cpuhw->sfb.num_sdb,
			     sample_rate_to_freq(&cpuhw->qsi, SAMPL_RATE(hwc)));

	/* Compute number of sample-data-blocks */
	num = compute_sfb_extent(ratio, cpuhw->sfb.num_sdb);
	if (num)
		sfb_account_allocs(num, hwc);

	debug_sprintf_event(sfdbg, 5, "sfb: overflow: overflow=%llu ratio=%lu"
			    " num=%lu\n", OVERFLOW_REG(hwc), ratio, num);
	OVERFLOW_REG(hwc) = 0;
}

/* extend_sampling_buffer() - Extend sampling buffer
 * @sfb:	Sampling buffer structure (for local CPU)
 * @hwc:	Perf event hardware structure
 *
 * Use this function to extend the sampling buffer based on the overflow counter
 * and postponed allocation extents stored in the specified Perf event hardware.
 *
 * Important: This function disables the sampling facility in order to safely
 *	      change the sampling buffer structure.  Do not call this function
 *	      when the PMU is active.
 */
static void extend_sampling_buffer(struct sf_buffer *sfb,
				   struct hw_perf_event *hwc)
{
	unsigned long num, num_old;
	int rc;

	num = sfb_pending_allocs(sfb, hwc);
	if (!num)
		return;
	num_old = sfb->num_sdb;

	/* Disable the sampling facility to reset any states and also
	 * clear pending measurement alerts.
	 */
	sf_disable();

	/* Extend the sampling buffer.
	 * This memory allocation typically happens in an atomic context when
	 * called by perf.  Because this is a reallocation, it is fine if the
	 * new SDB-request cannot be satisfied immediately.
	 */
	rc = realloc_sampling_buffer(sfb, num, GFP_ATOMIC);
	if (rc)
		debug_sprintf_event(sfdbg, 5, "sfb: extend: realloc "
				    "failed with rc=%i\n", rc);

	if (sfb_has_pending_allocs(sfb, hwc))
		debug_sprintf_event(sfdbg, 5, "sfb: extend: "
				    "req=%lu alloc=%lu remaining=%lu\n",
				    num, sfb->num_sdb - num_old,
				    sfb_pending_allocs(sfb, hwc));
}


/* Number of perf events counting hardware events */
static atomic_t num_events;
/* Used to avoid races in calling reserve/release_cpumf_hardware */
static DEFINE_MUTEX(pmc_reserve_mutex);

#define PMC_INIT      0
#define PMC_RELEASE   1
#define PMC_FAILURE   2
static void setup_pmc_cpu(void *flags)
{
	int err;
	struct cpu_hw_sf *cpusf = this_cpu_ptr(&cpu_hw_sf);

	err = 0;
	switch (*((int *) flags)) {
	case PMC_INIT:
		memset(cpusf, 0, sizeof(*cpusf));
		err = qsi(&cpusf->qsi);
		if (err)
			break;
		cpusf->flags |= PMU_F_RESERVED;
		err = sf_disable();
		if (err)
			pr_err("Switching off the sampling facility failed "
			       "with rc=%i\n", err);
		debug_sprintf_event(sfdbg, 5,
				    "setup_pmc_cpu: initialized: cpuhw=%p\n", cpusf);
		break;
	case PMC_RELEASE:
		cpusf->flags &= ~PMU_F_RESERVED;
		err = sf_disable();
		if (err) {
			pr_err("Switching off the sampling facility failed "
			       "with rc=%i\n", err);
		} else
			deallocate_buffers(cpusf);
		debug_sprintf_event(sfdbg, 5,
				    "setup_pmc_cpu: released: cpuhw=%p\n", cpusf);
		break;
	}
	if (err)
		*((int *) flags) |= PMC_FAILURE;
}

static void release_pmc_hardware(void)
{
	int flags = PMC_RELEASE;

	irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
	on_each_cpu(setup_pmc_cpu, &flags, 1);
}

static int reserve_pmc_hardware(void)
{
	int flags = PMC_INIT;

	on_each_cpu(setup_pmc_cpu, &flags, 1);
	if (flags & PMC_FAILURE) {
		release_pmc_hardware();
		return -ENODEV;
	}
	irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);

	return 0;
}

static void hw_perf_event_destroy(struct perf_event *event)
{
	/* Free raw sample buffer */
	if (RAWSAMPLE_REG(&event->hw))
		kfree((void *) RAWSAMPLE_REG(&event->hw));

	/* Release PMC if this is the last perf event */
	if (!atomic_add_unless(&num_events, -1, 1)) {
		mutex_lock(&pmc_reserve_mutex);
		if (atomic_dec_return(&num_events) == 0)
			release_pmc_hardware();
		mutex_unlock(&pmc_reserve_mutex);
	}
}

static void hw_init_period(struct hw_perf_event *hwc, u64 period)
{
	hwc->sample_period = period;
	hwc->last_period = hwc->sample_period;
	local64_set(&hwc->period_left, hwc->sample_period);
}

static void hw_reset_registers(struct hw_perf_event *hwc,
			       unsigned long *sdbt_origin)
{
	struct sf_raw_sample *sfr;

	/* (Re)set to first sample-data-block-table */
	TEAR_REG(hwc) = (unsigned long) sdbt_origin;

	/* (Re)set raw sampling buffer register */
	sfr = (struct sf_raw_sample *) RAWSAMPLE_REG(hwc);
	memset(&sfr->basic, 0, sizeof(sfr->basic));
	memset(&sfr->diag, 0, sfr->dsdes);
}

static unsigned long hw_limit_rate(const struct hws_qsi_info_block *si,
				   unsigned long rate)
{
	return clamp_t(unsigned long, rate,
		       si->min_sampl_rate, si->max_sampl_rate);
}

static int __hw_perf_event_init(struct perf_event *event)
{
	struct cpu_hw_sf *cpuhw;
	struct hws_qsi_info_block si;
	struct perf_event_attr *attr = &event->attr;
	struct hw_perf_event *hwc = &event->hw;
	unsigned long rate;
	int cpu, err;

	/* Reserve CPU-measurement sampling facility */
	err = 0;
	if (!atomic_inc_not_zero(&num_events)) {
		mutex_lock(&pmc_reserve_mutex);
		if (atomic_read(&num_events) == 0 && reserve_pmc_hardware())
			err = -EBUSY;
		else
			atomic_inc(&num_events);
		mutex_unlock(&pmc_reserve_mutex);
	}
	event->destroy = hw_perf_event_destroy;

	if (err)
		goto out;

	/* Access per-CPU sampling information (query sampling info) */
	/*
	 * The event->cpu value can be -1 to count on every CPU, for example,
	 * when attaching to a task.  If this is specified, use the query
	 * sampling info from the current CPU, otherwise use event->cpu to
	 * retrieve the per-CPU information.
	 * Later, cpuhw indicates whether to allocate sampling buffers for a
	 * particular CPU (cpuhw!=NULL) or each online CPU (cpuw==NULL).
	 */
	memset(&si, 0, sizeof(si));
	cpuhw = NULL;
	if (event->cpu == -1)
		qsi(&si);
	else {
		/* Event is pinned to a particular CPU, retrieve the per-CPU
		 * sampling structure for accessing the CPU-specific QSI.
		 */
		cpuhw = &per_cpu(cpu_hw_sf, event->cpu);
		si = cpuhw->qsi;
	}

	/* Check sampling facility authorization and, if not authorized,
	 * fall back to other PMUs.  It is safe to check any CPU because
	 * the authorization is identical for all configured CPUs.
	 */
	if (!si.as) {
		err = -ENOENT;
		goto out;
	}

	/* Always enable basic sampling */
	SAMPL_FLAGS(hwc) = PERF_CPUM_SF_BASIC_MODE;

	/* Check if diagnostic sampling is requested.  Deny if the required
	 * sampling authorization is missing.
	 */
	if (attr->config == PERF_EVENT_CPUM_SF_DIAG) {
		if (!si.ad) {
			err = -EPERM;
			goto out;
		}
		SAMPL_FLAGS(hwc) |= PERF_CPUM_SF_DIAG_MODE;
	}

	/* Check and set other sampling flags */
	if (attr->config1 & PERF_CPUM_SF_FULL_BLOCKS)
		SAMPL_FLAGS(hwc) |= PERF_CPUM_SF_FULL_BLOCKS;

	/* The sampling information (si) contains information about the
	 * min/max sampling intervals and the CPU speed.  So calculate the
	 * correct sampling interval and avoid the whole period adjust
	 * feedback loop.
	 */
	rate = 0;
	if (attr->freq) {
		rate = freq_to_sample_rate(&si, attr->sample_freq);
		rate = hw_limit_rate(&si, rate);
		attr->freq = 0;
		attr->sample_period = rate;
	} else {
		/* The min/max sampling rates specifies the valid range
		 * of sample periods.  If the specified sample period is
		 * out of range, limit the period to the range boundary.
		 */
		rate = hw_limit_rate(&si, hwc->sample_period);

		/* The perf core maintains a maximum sample rate that is
		 * configurable through the sysctl interface.  Ensure the
		 * sampling rate does not exceed this value.  This also helps
		 * to avoid throttling when pushing samples with
		 * perf_event_overflow().
		 */
		if (sample_rate_to_freq(&si, rate) >
		      sysctl_perf_event_sample_rate) {
			err = -EINVAL;
			debug_sprintf_event(sfdbg, 1, "Sampling rate exceeds maximum perf sample rate\n");
			goto out;
		}
	}
	SAMPL_RATE(hwc) = rate;
	hw_init_period(hwc, SAMPL_RATE(hwc));

	/* Initialize sample data overflow accounting */
	hwc->extra_reg.reg = REG_OVERFLOW;
	OVERFLOW_REG(hwc) = 0;

	/* Allocate the per-CPU sampling buffer using the CPU information
	 * from the event.  If the event is not pinned to a particular
	 * CPU (event->cpu == -1; or cpuhw == NULL), allocate sampling
	 * buffers for each online CPU.
	 */
	if (cpuhw)
		/* Event is pinned to a particular CPU */
		err = allocate_buffers(cpuhw, hwc);
	else {
		/* Event is not pinned, allocate sampling buffer on
		 * each online CPU
		 */
		for_each_online_cpu(cpu) {
			cpuhw = &per_cpu(cpu_hw_sf, cpu);
			err = allocate_buffers(cpuhw, hwc);
			if (err)
				break;
		}
	}
out:
	return err;
}

static int cpumsf_pmu_event_init(struct perf_event *event)
{
	int err;

	/* No support for taken branch sampling */
	if (has_branch_stack(event))
		return -EOPNOTSUPP;

	switch (event->attr.type) {
	case PERF_TYPE_RAW:
		if ((event->attr.config != PERF_EVENT_CPUM_SF) &&
		    (event->attr.config != PERF_EVENT_CPUM_SF_DIAG))
			return -ENOENT;
		break;
	case PERF_TYPE_HARDWARE:
		/* Support sampling of CPU cycles in addition to the
		 * counter facility.  However, the counter facility
		 * is more precise and, hence, restrict this PMU to
		 * sampling events only.
		 */
		if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES)
			return -ENOENT;
		if (!is_sampling_event(event))
			return -ENOENT;
		break;
	default:
		return -ENOENT;
	}

	/* Check online status of the CPU to which the event is pinned */
	if (event->cpu >= 0 && !cpu_online(event->cpu))
			return -ENODEV;

	/* Force reset of idle/hv excludes regardless of what the
	 * user requested.
	 */
	if (event->attr.exclude_hv)
		event->attr.exclude_hv = 0;
	if (event->attr.exclude_idle)
		event->attr.exclude_idle = 0;

	err = __hw_perf_event_init(event);
	if (unlikely(err))
		if (event->destroy)
			event->destroy(event);
	return err;
}

static void cpumsf_pmu_enable(struct pmu *pmu)
{
	struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);
	struct hw_perf_event *hwc;
	int err;

	if (cpuhw->flags & PMU_F_ENABLED)
		return;

	if (cpuhw->flags & PMU_F_ERR_MASK)
		return;

	/* Check whether to extent the sampling buffer.
	 *
	 * Two conditions trigger an increase of the sampling buffer for a
	 * perf event:
	 *    1. Postponed buffer allocations from the event initialization.
	 *    2. Sampling overflows that contribute to pending allocations.
	 *
	 * Note that the extend_sampling_buffer() function disables the sampling
	 * facility, but it can be fully re-enabled using sampling controls that
	 * have been saved in cpumsf_pmu_disable().
	 */
	if (cpuhw->event) {
		hwc = &cpuhw->event->hw;
		/* Account number of overflow-designated buffer extents */
		sfb_account_overflows(cpuhw, hwc);
		if (sfb_has_pending_allocs(&cpuhw->sfb, hwc))
			extend_sampling_buffer(&cpuhw->sfb, hwc);
	}

	/* (Re)enable the PMU and sampling facility */
	cpuhw->flags |= PMU_F_ENABLED;
	barrier();

	err = lsctl(&cpuhw->lsctl);
	if (err) {
		cpuhw->flags &= ~PMU_F_ENABLED;
		pr_err("Loading sampling controls failed: op=%i err=%i\n",
			1, err);
		return;
	}

	debug_sprintf_event(sfdbg, 6, "pmu_enable: es=%i cs=%i ed=%i cd=%i "
			    "tear=%p dear=%p\n", cpuhw->lsctl.es, cpuhw->lsctl.cs,
			    cpuhw->lsctl.ed, cpuhw->lsctl.cd,
			    (void *) cpuhw->lsctl.tear, (void *) cpuhw->lsctl.dear);
}

static void cpumsf_pmu_disable(struct pmu *pmu)
{
	struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);
	struct hws_lsctl_request_block inactive;
	struct hws_qsi_info_block si;
	int err;

	if (!(cpuhw->flags & PMU_F_ENABLED))
		return;

	if (cpuhw->flags & PMU_F_ERR_MASK)
		return;

	/* Switch off sampling activation control */
	inactive = cpuhw->lsctl;
	inactive.cs = 0;
	inactive.cd = 0;

	err = lsctl(&inactive);
	if (err) {
		pr_err("Loading sampling controls failed: op=%i err=%i\n",
			2, err);
		return;
	}

	/* Save state of TEAR and DEAR register contents */
	if (!qsi(&si)) {
		/* TEAR/DEAR values are valid only if the sampling facility is
		 * enabled.  Note that cpumsf_pmu_disable() might be called even
		 * for a disabled sampling facility because cpumsf_pmu_enable()
		 * controls the enable/disable state.
		 */
		if (si.es) {
			cpuhw->lsctl.tear = si.tear;
			cpuhw->lsctl.dear = si.dear;
		}
	} else
		debug_sprintf_event(sfdbg, 3, "cpumsf_pmu_disable: "
				    "qsi() failed with err=%i\n", err);

	cpuhw->flags &= ~PMU_F_ENABLED;
}

/* perf_exclude_event() - Filter event
 * @event:	The perf event
 * @regs:	pt_regs structure
 * @sde_regs:	Sample-data-entry (sde) regs structure
 *
 * Filter perf events according to their exclude specification.
 *
 * Return non-zero if the event shall be excluded.
 */
static int perf_exclude_event(struct perf_event *event, struct pt_regs *regs,
			      struct perf_sf_sde_regs *sde_regs)
{
	if (event->attr.exclude_user && user_mode(regs))
		return 1;
	if (event->attr.exclude_kernel && !user_mode(regs))
		return 1;
	if (event->attr.exclude_guest && sde_regs->in_guest)
		return 1;
	if (event->attr.exclude_host && !sde_regs->in_guest)
		return 1;
	return 0;
}

/* perf_push_sample() - Push samples to perf
 * @event:	The perf event
 * @sample:	Hardware sample data
 *
 * Use the hardware sample data to create perf event sample.  The sample
 * is the pushed to the event subsystem and the function checks for
 * possible event overflows.  If an event overflow occurs, the PMU is
 * stopped.
 *
 * Return non-zero if an event overflow occurred.
 */
static int perf_push_sample(struct perf_event *event, struct sf_raw_sample *sfr)
{
	int overflow;
	struct pt_regs regs;
	struct perf_sf_sde_regs *sde_regs;
	struct perf_sample_data data;
	struct perf_raw_record raw = {
		.frag = {
			.size = sfr->size,
			.data = sfr,
		},
	};

	/* Setup perf sample */
	perf_sample_data_init(&data, 0, event->hw.last_period);
	data.raw = &raw;

	/* Setup pt_regs to look like an CPU-measurement external interrupt
	 * using the Program Request Alert code.  The regs.int_parm_long
	 * field which is unused contains additional sample-data-entry related
	 * indicators.
	 */
	memset(&regs, 0, sizeof(regs));
	regs.int_code = 0x1407;
	regs.int_parm = CPU_MF_INT_SF_PRA;
	sde_regs = (struct perf_sf_sde_regs *) &regs.int_parm_long;

	psw_bits(regs.psw).ia	= sfr->basic.ia;
	psw_bits(regs.psw).dat	= sfr->basic.T;
	psw_bits(regs.psw).wait = sfr->basic.W;
	psw_bits(regs.psw).pstate = sfr->basic.P;
	psw_bits(regs.psw).as	= sfr->basic.AS;

	/*
	 * Use the hardware provided configuration level to decide if the
	 * sample belongs to a guest or host. If that is not available,
	 * fall back to the following heuristics:
	 * A non-zero guest program parameter always indicates a guest
	 * sample. Some early samples or samples from guests without
	 * lpp usage would be misaccounted to the host. We use the asn
	 * value as an addon heuristic to detect most of these guest samples.
	 * If the value differs from 0xffff (the host value), we assume to
	 * be a KVM guest.
	 */
	switch (sfr->basic.CL) {
	case 1: /* logical partition */
		sde_regs->in_guest = 0;
		break;
	case 2: /* virtual machine */
		sde_regs->in_guest = 1;
		break;
	default: /* old machine, use heuristics */
		if (sfr->basic.gpp || sfr->basic.prim_asn != 0xffff)
			sde_regs->in_guest = 1;
		break;
	}

	overflow = 0;
	if (perf_exclude_event(event, &regs, sde_regs))
		goto out;
	if (perf_event_overflow(event, &data, &regs)) {
		overflow = 1;
		event->pmu->stop(event, 0);
	}
	perf_event_update_userpage(event);
out:
	return overflow;
}

static void perf_event_count_update(struct perf_event *event, u64 count)
{
	local64_add(count, &event->count);
}

static int sample_format_is_valid(struct hws_combined_entry *sample,
				   unsigned int flags)
{
	if (likely(flags & PERF_CPUM_SF_BASIC_MODE))
		/* Only basic-sampling data entries with data-entry-format
		 * version of 0x0001 can be processed.
		 */
		if (sample->basic.def != 0x0001)
			return 0;
	if (flags & PERF_CPUM_SF_DIAG_MODE)
		/* The data-entry-format number of diagnostic-sampling data
		 * entries can vary.  Because diagnostic data is just passed
		 * through, do only a sanity check on the DEF.
		 */
		if (sample->diag.def < 0x8001)
			return 0;
	return 1;
}

static int sample_is_consistent(struct hws_combined_entry *sample,
				unsigned long flags)
{
	/* This check applies only to basic-sampling data entries of potentially
	 * combined-sampling data entries.  Invalid entries cannot be processed
	 * by the PMU and, thus, do not deliver an associated
	 * diagnostic-sampling data entry.
	 */
	if (unlikely(!(flags & PERF_CPUM_SF_BASIC_MODE)))
		return 0;
	/*
	 * Samples are skipped, if they are invalid or for which the
	 * instruction address is not predictable, i.e., the wait-state bit is
	 * set.
	 */
	if (sample->basic.I || sample->basic.W)
		return 0;
	return 1;
}

static void reset_sample_slot(struct hws_combined_entry *sample,
			      unsigned long flags)
{
	if (likely(flags & PERF_CPUM_SF_BASIC_MODE))
		sample->basic.def = 0;
	if (flags & PERF_CPUM_SF_DIAG_MODE)
		sample->diag.def = 0;
}

static void sfr_store_sample(struct sf_raw_sample *sfr,
			     struct hws_combined_entry *sample)
{
	if (likely(sfr->format & PERF_CPUM_SF_BASIC_MODE))
		sfr->basic = sample->basic;
	if (sfr->format & PERF_CPUM_SF_DIAG_MODE)
		memcpy(&sfr->diag, &sample->diag, sfr->dsdes);
}

static void debug_sample_entry(struct hws_combined_entry *sample,
			       struct hws_trailer_entry *te,
			       unsigned long flags)
{
	debug_sprintf_event(sfdbg, 4, "hw_collect_samples: Found unknown "
			    "sampling data entry: te->f=%i basic.def=%04x (%p)"
			    " diag.def=%04x (%p)\n", te->f,
			    sample->basic.def, &sample->basic,
			    (flags & PERF_CPUM_SF_DIAG_MODE)
					? sample->diag.def : 0xFFFF,
			    (flags & PERF_CPUM_SF_DIAG_MODE)
					?  &sample->diag : NULL);
}

/* hw_collect_samples() - Walk through a sample-data-block and collect samples
 * @event:	The perf event
 * @sdbt:	Sample-data-block table
 * @overflow:	Event overflow counter
 *
 * Walks through a sample-data-block and collects sampling data entries that are
 * then pushed to the perf event subsystem.  Depending on the sampling function,
 * there can be either basic-sampling or combined-sampling data entries.  A
 * combined-sampling data entry consists of a basic- and a diagnostic-sampling
 * data entry.	The sampling function is determined by the flags in the perf
 * event hardware structure.  The function always works with a combined-sampling
 * data entry but ignores the the diagnostic portion if it is not available.
 *
 * Note that the implementation focuses on basic-sampling data entries and, if
 * such an entry is not valid, the entire combined-sampling data entry is
 * ignored.
 *
 * The overflow variables counts the number of samples that has been discarded
 * due to a perf event overflow.
 */
static void hw_collect_samples(struct perf_event *event, unsigned long *sdbt,
			       unsigned long long *overflow)
{
	unsigned long flags = SAMPL_FLAGS(&event->hw);
	struct hws_combined_entry *sample;
	struct hws_trailer_entry *te;
	struct sf_raw_sample *sfr;
	size_t sample_size;

	/* Prepare and initialize raw sample data */
	sfr = (struct sf_raw_sample *) RAWSAMPLE_REG(&event->hw);
	sfr->format = flags & PERF_CPUM_SF_MODE_MASK;

	sample_size = event_sample_size(&event->hw);
	te = (struct hws_trailer_entry *) trailer_entry_ptr(*sdbt);
	sample = (struct hws_combined_entry *) *sdbt;
	while ((unsigned long *) sample < (unsigned long *) te) {
		/* Check for an empty sample */
		if (!sample->basic.def)
			break;

		/* Update perf event period */
		perf_event_count_update(event, SAMPL_RATE(&event->hw));

		/* Check sampling data entry */
		if (sample_format_is_valid(sample, flags)) {
			/* If an event overflow occurred, the PMU is stopped to
			 * throttle event delivery.  Remaining sample data is
			 * discarded.
			 */
			if (!*overflow) {
				if (sample_is_consistent(sample, flags)) {
					/* Deliver sample data to perf */
					sfr_store_sample(sfr, sample);
					*overflow = perf_push_sample(event, sfr);
				}
			} else
				/* Count discarded samples */
				*overflow += 1;
		} else {
			debug_sample_entry(sample, te, flags);
			/* Sample slot is not yet written or other record.
			 *
			 * This condition can occur if the buffer was reused
			 * from a combined basic- and diagnostic-sampling.
			 * If only basic-sampling is then active, entries are
			 * written into the larger diagnostic entries.
			 * This is typically the case for sample-data-blocks
			 * that are not full.  Stop processing if the first
			 * invalid format was detected.
			 */
			if (!te->f)
				break;
		}

		/* Reset sample slot and advance to next sample */
		reset_sample_slot(sample, flags);
		sample += sample_size;
	}
}

/* hw_perf_event_update() - Process sampling buffer
 * @event:	The perf event
 * @flush_all:	Flag to also flush partially filled sample-data-blocks
 *
 * Processes the sampling buffer and create perf event samples.
 * The sampling buffer position are retrieved and saved in the TEAR_REG
 * register of the specified perf event.
 *
 * Only full sample-data-blocks are processed.	Specify the flash_all flag
 * to also walk through partially filled sample-data-blocks.  It is ignored
 * if PERF_CPUM_SF_FULL_BLOCKS is set.	The PERF_CPUM_SF_FULL_BLOCKS flag
 * enforces the processing of full sample-data-blocks only (trailer entries
 * with the block-full-indicator bit set).
 */
static void hw_perf_event_update(struct perf_event *event, int flush_all)
{
	struct hw_perf_event *hwc = &event->hw;
	struct hws_trailer_entry *te;
	unsigned long *sdbt;
	unsigned long long event_overflow, sampl_overflow, num_sdb, te_flags;
	int done;

	if (flush_all && SDB_FULL_BLOCKS(hwc))
		flush_all = 0;

	sdbt = (unsigned long *) TEAR_REG(hwc);
	done = event_overflow = sampl_overflow = num_sdb = 0;
	while (!done) {
		/* Get the trailer entry of the sample-data-block */
		te = (struct hws_trailer_entry *) trailer_entry_ptr(*sdbt);

		/* Leave loop if no more work to do (block full indicator) */
		if (!te->f) {
			done = 1;
			if (!flush_all)
				break;
		}

		/* Check the sample overflow count */
		if (te->overflow)
			/* Account sample overflows and, if a particular limit
			 * is reached, extend the sampling buffer.
			 * For details, see sfb_account_overflows().
			 */
			sampl_overflow += te->overflow;

		/* Timestamps are valid for full sample-data-blocks only */
		debug_sprintf_event(sfdbg, 6, "hw_perf_event_update: sdbt=%p "
				    "overflow=%llu timestamp=0x%llx\n",
				    sdbt, te->overflow,
				    (te->f) ? trailer_timestamp(te) : 0ULL);

		/* Collect all samples from a single sample-data-block and
		 * flag if an (perf) event overflow happened.  If so, the PMU
		 * is stopped and remaining samples will be discarded.
		 */
		hw_collect_samples(event, sdbt, &event_overflow);
		num_sdb++;

		/* Reset trailer (using compare-double-and-swap) */
		do {
			te_flags = te->flags & ~SDB_TE_BUFFER_FULL_MASK;
			te_flags |= SDB_TE_ALERT_REQ_MASK;
		} while (!cmpxchg_double(&te->flags, &te->overflow,
					 te->flags, te->overflow,
					 te_flags, 0ULL));

		/* Advance to next sample-data-block */
		sdbt++;
		if (is_link_entry(sdbt))
			sdbt = get_next_sdbt(sdbt);

		/* Update event hardware registers */
		TEAR_REG(hwc) = (unsigned long) sdbt;

		/* Stop processing sample-data if all samples of the current
		 * sample-data-block were flushed even if it was not full.
		 */
		if (flush_all && done)
			break;

		/* If an event overflow happened, discard samples by
		 * processing any remaining sample-data-blocks.
		 */
		if (event_overflow)
			flush_all = 1;
	}

	/* Account sample overflows in the event hardware structure */
	if (sampl_overflow)
		OVERFLOW_REG(hwc) = DIV_ROUND_UP(OVERFLOW_REG(hwc) +
						 sampl_overflow, 1 + num_sdb);
	if (sampl_overflow || event_overflow)
		debug_sprintf_event(sfdbg, 4, "hw_perf_event_update: "
				    "overflow stats: sample=%llu event=%llu\n",
				    sampl_overflow, event_overflow);
}

static void cpumsf_pmu_read(struct perf_event *event)
{
	/* Nothing to do ... updates are interrupt-driven */
}

/* Activate sampling control.
 * Next call of pmu_enable() starts sampling.
 */
static void cpumsf_pmu_start(struct perf_event *event, int flags)
{
	struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);

	if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
		return;

	if (flags & PERF_EF_RELOAD)
		WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));

	perf_pmu_disable(event->pmu);
	event->hw.state = 0;
	cpuhw->lsctl.cs = 1;
	if (SAMPL_DIAG_MODE(&event->hw))
		cpuhw->lsctl.cd = 1;
	perf_pmu_enable(event->pmu);
}

/* Deactivate sampling control.
 * Next call of pmu_enable() stops sampling.
 */
static void cpumsf_pmu_stop(struct perf_event *event, int flags)
{
	struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);

	if (event->hw.state & PERF_HES_STOPPED)
		return;

	perf_pmu_disable(event->pmu);
	cpuhw->lsctl.cs = 0;
	cpuhw->lsctl.cd = 0;
	event->hw.state |= PERF_HES_STOPPED;

	if ((flags & PERF_EF_UPDATE) && !(event->hw.state & PERF_HES_UPTODATE)) {
		hw_perf_event_update(event, 1);
		event->hw.state |= PERF_HES_UPTODATE;
	}
	perf_pmu_enable(event->pmu);
}

static int cpumsf_pmu_add(struct perf_event *event, int flags)
{
	struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);
	int err;

	if (cpuhw->flags & PMU_F_IN_USE)
		return -EAGAIN;

	if (!cpuhw->sfb.sdbt)
		return -EINVAL;

	err = 0;
	perf_pmu_disable(event->pmu);

	event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;

	/* Set up sampling controls.  Always program the sampling register
	 * using the SDB-table start.  Reset TEAR_REG event hardware register
	 * that is used by hw_perf_event_update() to store the sampling buffer
	 * position after samples have been flushed.
	 */
	cpuhw->lsctl.s = 0;
	cpuhw->lsctl.h = 1;
	cpuhw->lsctl.tear = (unsigned long) cpuhw->sfb.sdbt;
	cpuhw->lsctl.dear = *(unsigned long *) cpuhw->sfb.sdbt;
	cpuhw->lsctl.interval = SAMPL_RATE(&event->hw);
	hw_reset_registers(&event->hw, cpuhw->sfb.sdbt);

	/* Ensure sampling functions are in the disabled state.  If disabled,
	 * switch on sampling enable control. */
	if (WARN_ON_ONCE(cpuhw->lsctl.es == 1 || cpuhw->lsctl.ed == 1)) {
		err = -EAGAIN;
		goto out;
	}
	cpuhw->lsctl.es = 1;
	if (SAMPL_DIAG_MODE(&event->hw))
		cpuhw->lsctl.ed = 1;

	/* Set in_use flag and store event */
	cpuhw->event = event;
	cpuhw->flags |= PMU_F_IN_USE;

	if (flags & PERF_EF_START)
		cpumsf_pmu_start(event, PERF_EF_RELOAD);
out:
	perf_event_update_userpage(event);
	perf_pmu_enable(event->pmu);
	return err;
}

static void cpumsf_pmu_del(struct perf_event *event, int flags)
{
	struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);

	perf_pmu_disable(event->pmu);
	cpumsf_pmu_stop(event, PERF_EF_UPDATE);

	cpuhw->lsctl.es = 0;
	cpuhw->lsctl.ed = 0;
	cpuhw->flags &= ~PMU_F_IN_USE;
	cpuhw->event = NULL;

	perf_event_update_userpage(event);
	perf_pmu_enable(event->pmu);
}

CPUMF_EVENT_ATTR(SF, SF_CYCLES_BASIC, PERF_EVENT_CPUM_SF);
CPUMF_EVENT_ATTR(SF, SF_CYCLES_BASIC_DIAG, PERF_EVENT_CPUM_SF_DIAG);

static struct attribute *cpumsf_pmu_events_attr[] = {
	CPUMF_EVENT_PTR(SF, SF_CYCLES_BASIC),
	NULL,
	NULL,
};

PMU_FORMAT_ATTR(event, "config:0-63");

static struct attribute *cpumsf_pmu_format_attr[] = {
	&format_attr_event.attr,
	NULL,
};

static struct attribute_group cpumsf_pmu_events_group = {
	.name = "events",
	.attrs = cpumsf_pmu_events_attr,
};
static struct attribute_group cpumsf_pmu_format_group = {
	.name = "format",
	.attrs = cpumsf_pmu_format_attr,
};
static const struct attribute_group *cpumsf_pmu_attr_groups[] = {
	&cpumsf_pmu_events_group,
	&cpumsf_pmu_format_group,
	NULL,
};

static struct pmu cpumf_sampling = {
	.pmu_enable   = cpumsf_pmu_enable,
	.pmu_disable  = cpumsf_pmu_disable,

	.event_init   = cpumsf_pmu_event_init,
	.add	      = cpumsf_pmu_add,
	.del	      = cpumsf_pmu_del,

	.start	      = cpumsf_pmu_start,
	.stop	      = cpumsf_pmu_stop,
	.read	      = cpumsf_pmu_read,

	.attr_groups  = cpumsf_pmu_attr_groups,
};

static void cpumf_measurement_alert(struct ext_code ext_code,
				    unsigned int alert, unsigned long unused)
{
	struct cpu_hw_sf *cpuhw;

	if (!(alert & CPU_MF_INT_SF_MASK))
		return;
	inc_irq_stat(IRQEXT_CMS);
	cpuhw = this_cpu_ptr(&cpu_hw_sf);

	/* Measurement alerts are shared and might happen when the PMU
	 * is not reserved.  Ignore these alerts in this case. */
	if (!(cpuhw->flags & PMU_F_RESERVED))
		return;

	/* The processing below must take care of multiple alert events that
	 * might be indicated concurrently. */

	/* Program alert request */
	if (alert & CPU_MF_INT_SF_PRA) {
		if (cpuhw->flags & PMU_F_IN_USE)
			hw_perf_event_update(cpuhw->event, 0);
		else
			WARN_ON_ONCE(!(cpuhw->flags & PMU_F_IN_USE));
	}

	/* Report measurement alerts only for non-PRA codes */
	if (alert != CPU_MF_INT_SF_PRA)
		debug_sprintf_event(sfdbg, 6, "measurement alert: 0x%x\n", alert);

	/* Sampling authorization change request */
	if (alert & CPU_MF_INT_SF_SACA)
		qsi(&cpuhw->qsi);

	/* Loss of sample data due to high-priority machine activities */
	if (alert & CPU_MF_INT_SF_LSDA) {
		pr_err("Sample data was lost\n");
		cpuhw->flags |= PMU_F_ERR_LSDA;
		sf_disable();
	}

	/* Invalid sampling buffer entry */
	if (alert & (CPU_MF_INT_SF_IAE|CPU_MF_INT_SF_ISE)) {
		pr_err("A sampling buffer entry is incorrect (alert=0x%x)\n",
		       alert);
		cpuhw->flags |= PMU_F_ERR_IBE;
		sf_disable();
	}
}
static int cpusf_pmu_setup(unsigned int cpu, int flags)
{
	/* Ignore the notification if no events are scheduled on the PMU.
	 * This might be racy...
	 */
	if (!atomic_read(&num_events))
		return 0;

	local_irq_disable();
	setup_pmc_cpu(&flags);
	local_irq_enable();
	return 0;
}

static int s390_pmu_sf_online_cpu(unsigned int cpu)
{
	return cpusf_pmu_setup(cpu, PMC_INIT);
}

static int s390_pmu_sf_offline_cpu(unsigned int cpu)
{
	return cpusf_pmu_setup(cpu, PMC_RELEASE);
}

static int param_get_sfb_size(char *buffer, const struct kernel_param *kp)
{
	if (!cpum_sf_avail())
		return -ENODEV;
	return sprintf(buffer, "%lu,%lu", CPUM_SF_MIN_SDB, CPUM_SF_MAX_SDB);
}

static int param_set_sfb_size(const char *val, const struct kernel_param *kp)
{
	int rc;
	unsigned long min, max;

	if (!cpum_sf_avail())
		return -ENODEV;
	if (!val || !strlen(val))
		return -EINVAL;

	/* Valid parameter values: "min,max" or "max" */
	min = CPUM_SF_MIN_SDB;
	max = CPUM_SF_MAX_SDB;
	if (strchr(val, ','))
		rc = (sscanf(val, "%lu,%lu", &min, &max) == 2) ? 0 : -EINVAL;
	else
		rc = kstrtoul(val, 10, &max);

	if (min < 2 || min >= max || max > get_num_physpages())
		rc = -EINVAL;
	if (rc)
		return rc;

	sfb_set_limits(min, max);
	pr_info("The sampling buffer limits have changed to: "
		"min=%lu max=%lu (diag=x%lu)\n",
		CPUM_SF_MIN_SDB, CPUM_SF_MAX_SDB, CPUM_SF_SDB_DIAG_FACTOR);
	return 0;
}

#define param_check_sfb_size(name, p) __param_check(name, p, void)
static const struct kernel_param_ops param_ops_sfb_size = {
	.set = param_set_sfb_size,
	.get = param_get_sfb_size,
};

#define RS_INIT_FAILURE_QSI	  0x0001
#define RS_INIT_FAILURE_BSDES	  0x0002
#define RS_INIT_FAILURE_ALRT	  0x0003
#define RS_INIT_FAILURE_PERF	  0x0004
static void __init pr_cpumsf_err(unsigned int reason)
{
	pr_err("Sampling facility support for perf is not available: "
	       "reason=%04x\n", reason);
}

static int __init init_cpum_sampling_pmu(void)
{
	struct hws_qsi_info_block si;
	int err;

	if (!cpum_sf_avail())
		return -ENODEV;

	memset(&si, 0, sizeof(si));
	if (qsi(&si)) {
		pr_cpumsf_err(RS_INIT_FAILURE_QSI);
		return -ENODEV;
	}

	if (si.bsdes != sizeof(struct hws_basic_entry)) {
		pr_cpumsf_err(RS_INIT_FAILURE_BSDES);
		return -EINVAL;
	}

	if (si.ad) {
		sfb_set_limits(CPUM_SF_MIN_SDB, CPUM_SF_MAX_SDB);
		cpumsf_pmu_events_attr[1] =
			CPUMF_EVENT_PTR(SF, SF_CYCLES_BASIC_DIAG);
	}

	sfdbg = debug_register(KMSG_COMPONENT, 2, 1, 80);
	if (!sfdbg)
		pr_err("Registering for s390dbf failed\n");
	debug_register_view(sfdbg, &debug_sprintf_view);

	err = register_external_irq(EXT_IRQ_MEASURE_ALERT,
				    cpumf_measurement_alert);
	if (err) {
		pr_cpumsf_err(RS_INIT_FAILURE_ALRT);
		goto out;
	}

	err = perf_pmu_register(&cpumf_sampling, "cpum_sf", PERF_TYPE_RAW);
	if (err) {
		pr_cpumsf_err(RS_INIT_FAILURE_PERF);
		unregister_external_irq(EXT_IRQ_MEASURE_ALERT,
					cpumf_measurement_alert);
		goto out;
	}

	cpuhp_setup_state(CPUHP_AP_PERF_S390_SF_ONLINE, "perf/s390/sf:online",
			  s390_pmu_sf_online_cpu, s390_pmu_sf_offline_cpu);
out:
	return err;
}
arch_initcall(init_cpum_sampling_pmu);
core_param(cpum_sfb_size, CPUM_SF_MAX_SDB, sfb_size, 0640);