aboutsummaryrefslogtreecommitdiff
path: root/arch/s390/net/bpf_jit_comp.c
blob: 167b31b186c1313c2cea094ee3b972233d61a608 (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
/*
 * BPF Jit compiler for s390.
 *
 * Minimum build requirements:
 *
 *  - HAVE_MARCH_Z196_FEATURES: laal, laalg
 *  - HAVE_MARCH_Z10_FEATURES: msfi, cgrj, clgrj
 *  - HAVE_MARCH_Z9_109_FEATURES: alfi, llilf, clfi, oilf, nilf
 *  - PACK_STACK
 *  - 64BIT
 *
 * Copyright IBM Corp. 2012,2015
 *
 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
 *	      Michael Holzheu <holzheu@linux.vnet.ibm.com>
 */

#define KMSG_COMPONENT "bpf_jit"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/init.h>
#include <linux/bpf.h>
#include <asm/cacheflush.h>
#include <asm/dis.h>
#include "bpf_jit.h"

int bpf_jit_enable __read_mostly;

struct bpf_jit {
	u32 seen;		/* Flags to remember seen eBPF instructions */
	u32 seen_reg[16];	/* Array to remember which registers are used */
	u32 *addrs;		/* Array with relative instruction addresses */
	u8 *prg_buf;		/* Start of program */
	int size;		/* Size of program and literal pool */
	int size_prg;		/* Size of program */
	int prg;		/* Current position in program */
	int lit_start;		/* Start of literal pool */
	int lit;		/* Current position in literal pool */
	int base_ip;		/* Base address for literal pool */
	int ret0_ip;		/* Address of return 0 */
	int exit_ip;		/* Address of exit */
	int tail_call_start;	/* Tail call start offset */
	int labels[1];		/* Labels for local jumps */
};

#define BPF_SIZE_MAX	0xffff	/* Max size for program (16 bit branches) */

#define SEEN_SKB	1	/* skb access */
#define SEEN_MEM	2	/* use mem[] for temporary storage */
#define SEEN_RET0	4	/* ret0_ip points to a valid return 0 */
#define SEEN_LITERAL	8	/* code uses literals */
#define SEEN_FUNC	16	/* calls C functions */
#define SEEN_TAIL_CALL	32	/* code uses tail calls */
#define SEEN_SKB_CHANGE	64	/* code changes skb data */
#define SEEN_REG_AX	128	/* code uses constant blinding */
#define SEEN_STACK	(SEEN_FUNC | SEEN_MEM | SEEN_SKB)

/*
 * s390 registers
 */
#define REG_W0		(MAX_BPF_JIT_REG + 0)	/* Work register 1 (even) */
#define REG_W1		(MAX_BPF_JIT_REG + 1)	/* Work register 2 (odd) */
#define REG_SKB_DATA	(MAX_BPF_JIT_REG + 2)	/* SKB data register */
#define REG_L		(MAX_BPF_JIT_REG + 3)	/* Literal pool register */
#define REG_15		(MAX_BPF_JIT_REG + 4)	/* Register 15 */
#define REG_0		REG_W0			/* Register 0 */
#define REG_1		REG_W1			/* Register 1 */
#define REG_2		BPF_REG_1		/* Register 2 */
#define REG_14		BPF_REG_0		/* Register 14 */

/*
 * Mapping of BPF registers to s390 registers
 */
static const int reg2hex[] = {
	/* Return code */
	[BPF_REG_0]	= 14,
	/* Function parameters */
	[BPF_REG_1]	= 2,
	[BPF_REG_2]	= 3,
	[BPF_REG_3]	= 4,
	[BPF_REG_4]	= 5,
	[BPF_REG_5]	= 6,
	/* Call saved registers */
	[BPF_REG_6]	= 7,
	[BPF_REG_7]	= 8,
	[BPF_REG_8]	= 9,
	[BPF_REG_9]	= 10,
	/* BPF stack pointer */
	[BPF_REG_FP]	= 13,
	/* Register for blinding (shared with REG_SKB_DATA) */
	[BPF_REG_AX]	= 12,
	/* SKB data pointer */
	[REG_SKB_DATA]	= 12,
	/* Work registers for s390x backend */
	[REG_W0]	= 0,
	[REG_W1]	= 1,
	[REG_L]		= 11,
	[REG_15]	= 15,
};

static inline u32 reg(u32 dst_reg, u32 src_reg)
{
	return reg2hex[dst_reg] << 4 | reg2hex[src_reg];
}

static inline u32 reg_high(u32 reg)
{
	return reg2hex[reg] << 4;
}

static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
{
	u32 r1 = reg2hex[b1];

	if (!jit->seen_reg[r1] && r1 >= 6 && r1 <= 15)
		jit->seen_reg[r1] = 1;
}

#define REG_SET_SEEN(b1)					\
({								\
	reg_set_seen(jit, b1);					\
})

#define REG_SEEN(b1) jit->seen_reg[reg2hex[(b1)]]

/*
 * EMIT macros for code generation
 */

#define _EMIT2(op)						\
({								\
	if (jit->prg_buf)					\
		*(u16 *) (jit->prg_buf + jit->prg) = op;	\
	jit->prg += 2;						\
})

#define EMIT2(op, b1, b2)					\
({								\
	_EMIT2(op | reg(b1, b2));				\
	REG_SET_SEEN(b1);					\
	REG_SET_SEEN(b2);					\
})

#define _EMIT4(op)						\
({								\
	if (jit->prg_buf)					\
		*(u32 *) (jit->prg_buf + jit->prg) = op;	\
	jit->prg += 4;						\
})

#define EMIT4(op, b1, b2)					\
({								\
	_EMIT4(op | reg(b1, b2));				\
	REG_SET_SEEN(b1);					\
	REG_SET_SEEN(b2);					\
})

#define EMIT4_RRF(op, b1, b2, b3)				\
({								\
	_EMIT4(op | reg_high(b3) << 8 | reg(b1, b2));		\
	REG_SET_SEEN(b1);					\
	REG_SET_SEEN(b2);					\
	REG_SET_SEEN(b3);					\
})

#define _EMIT4_DISP(op, disp)					\
({								\
	unsigned int __disp = (disp) & 0xfff;			\
	_EMIT4(op | __disp);					\
})

#define EMIT4_DISP(op, b1, b2, disp)				\
({								\
	_EMIT4_DISP(op | reg_high(b1) << 16 |			\
		    reg_high(b2) << 8, disp);			\
	REG_SET_SEEN(b1);					\
	REG_SET_SEEN(b2);					\
})

#define EMIT4_IMM(op, b1, imm)					\
({								\
	unsigned int __imm = (imm) & 0xffff;			\
	_EMIT4(op | reg_high(b1) << 16 | __imm);		\
	REG_SET_SEEN(b1);					\
})

#define EMIT4_PCREL(op, pcrel)					\
({								\
	long __pcrel = ((pcrel) >> 1) & 0xffff;			\
	_EMIT4(op | __pcrel);					\
})

#define _EMIT6(op1, op2)					\
({								\
	if (jit->prg_buf) {					\
		*(u32 *) (jit->prg_buf + jit->prg) = op1;	\
		*(u16 *) (jit->prg_buf + jit->prg + 4) = op2;	\
	}							\
	jit->prg += 6;						\
})

#define _EMIT6_DISP(op1, op2, disp)				\
({								\
	unsigned int __disp = (disp) & 0xfff;			\
	_EMIT6(op1 | __disp, op2);				\
})

#define _EMIT6_DISP_LH(op1, op2, disp)				\
({								\
	u32 _disp = (u32) disp;					\
	unsigned int __disp_h = _disp & 0xff000;		\
	unsigned int __disp_l = _disp & 0x00fff;		\
	_EMIT6(op1 | __disp_l, op2 | __disp_h >> 4);		\
})

#define EMIT6_DISP_LH(op1, op2, b1, b2, b3, disp)		\
({								\
	_EMIT6_DISP_LH(op1 | reg(b1, b2) << 16 |		\
		       reg_high(b3) << 8, op2, disp);		\
	REG_SET_SEEN(b1);					\
	REG_SET_SEEN(b2);					\
	REG_SET_SEEN(b3);					\
})

#define EMIT6_PCREL_LABEL(op1, op2, b1, b2, label, mask)	\
({								\
	int rel = (jit->labels[label] - jit->prg) >> 1;		\
	_EMIT6(op1 | reg(b1, b2) << 16 | (rel & 0xffff),	\
	       op2 | mask << 12);				\
	REG_SET_SEEN(b1);					\
	REG_SET_SEEN(b2);					\
})

#define EMIT6_PCREL_IMM_LABEL(op1, op2, b1, imm, label, mask)	\
({								\
	int rel = (jit->labels[label] - jit->prg) >> 1;		\
	_EMIT6(op1 | (reg_high(b1) | mask) << 16 |		\
		(rel & 0xffff), op2 | (imm & 0xff) << 8);	\
	REG_SET_SEEN(b1);					\
	BUILD_BUG_ON(((unsigned long) imm) > 0xff);		\
})

#define EMIT6_PCREL(op1, op2, b1, b2, i, off, mask)		\
({								\
	/* Branch instruction needs 6 bytes */			\
	int rel = (addrs[i + off + 1] - (addrs[i + 1] - 6)) / 2;\
	_EMIT6(op1 | reg(b1, b2) << 16 | (rel & 0xffff), op2 | mask);	\
	REG_SET_SEEN(b1);					\
	REG_SET_SEEN(b2);					\
})

#define _EMIT6_IMM(op, imm)					\
({								\
	unsigned int __imm = (imm);				\
	_EMIT6(op | (__imm >> 16), __imm & 0xffff);		\
})

#define EMIT6_IMM(op, b1, imm)					\
({								\
	_EMIT6_IMM(op | reg_high(b1) << 16, imm);		\
	REG_SET_SEEN(b1);					\
})

#define EMIT_CONST_U32(val)					\
({								\
	unsigned int ret;					\
	ret = jit->lit - jit->base_ip;				\
	jit->seen |= SEEN_LITERAL;				\
	if (jit->prg_buf)					\
		*(u32 *) (jit->prg_buf + jit->lit) = (u32) val;	\
	jit->lit += 4;						\
	ret;							\
})

#define EMIT_CONST_U64(val)					\
({								\
	unsigned int ret;					\
	ret = jit->lit - jit->base_ip;				\
	jit->seen |= SEEN_LITERAL;				\
	if (jit->prg_buf)					\
		*(u64 *) (jit->prg_buf + jit->lit) = (u64) val;	\
	jit->lit += 8;						\
	ret;							\
})

#define EMIT_ZERO(b1)						\
({								\
	/* llgfr %dst,%dst (zero extend to 64 bit) */		\
	EMIT4(0xb9160000, b1, b1);				\
	REG_SET_SEEN(b1);					\
})

/*
 * Fill whole space with illegal instructions
 */
static void jit_fill_hole(void *area, unsigned int size)
{
	memset(area, 0, size);
}

/*
 * Save registers from "rs" (register start) to "re" (register end) on stack
 */
static void save_regs(struct bpf_jit *jit, u32 rs, u32 re)
{
	u32 off = STK_OFF_R6 + (rs - 6) * 8;

	if (rs == re)
		/* stg %rs,off(%r15) */
		_EMIT6(0xe300f000 | rs << 20 | off, 0x0024);
	else
		/* stmg %rs,%re,off(%r15) */
		_EMIT6_DISP(0xeb00f000 | rs << 20 | re << 16, 0x0024, off);
}

/*
 * Restore registers from "rs" (register start) to "re" (register end) on stack
 */
static void restore_regs(struct bpf_jit *jit, u32 rs, u32 re)
{
	u32 off = STK_OFF_R6 + (rs - 6) * 8;

	if (jit->seen & SEEN_STACK)
		off += STK_OFF;

	if (rs == re)
		/* lg %rs,off(%r15) */
		_EMIT6(0xe300f000 | rs << 20 | off, 0x0004);
	else
		/* lmg %rs,%re,off(%r15) */
		_EMIT6_DISP(0xeb00f000 | rs << 20 | re << 16, 0x0004, off);
}

/*
 * Return first seen register (from start)
 */
static int get_start(struct bpf_jit *jit, int start)
{
	int i;

	for (i = start; i <= 15; i++) {
		if (jit->seen_reg[i])
			return i;
	}
	return 0;
}

/*
 * Return last seen register (from start) (gap >= 2)
 */
static int get_end(struct bpf_jit *jit, int start)
{
	int i;

	for (i = start; i < 15; i++) {
		if (!jit->seen_reg[i] && !jit->seen_reg[i + 1])
			return i - 1;
	}
	return jit->seen_reg[15] ? 15 : 14;
}

#define REGS_SAVE	1
#define REGS_RESTORE	0
/*
 * Save and restore clobbered registers (6-15) on stack.
 * We save/restore registers in chunks with gap >= 2 registers.
 */
static void save_restore_regs(struct bpf_jit *jit, int op)
{

	int re = 6, rs;

	do {
		rs = get_start(jit, re);
		if (!rs)
			break;
		re = get_end(jit, rs + 1);
		if (op == REGS_SAVE)
			save_regs(jit, rs, re);
		else
			restore_regs(jit, rs, re);
		re++;
	} while (re <= 15);
}

/*
 * For SKB access %b1 contains the SKB pointer. For "bpf_jit.S"
 * we store the SKB header length on the stack and the SKB data
 * pointer in REG_SKB_DATA if BPF_REG_AX is not used.
 */
static void emit_load_skb_data_hlen(struct bpf_jit *jit)
{
	/* Header length: llgf %w1,<len>(%b1) */
	EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_1,
		      offsetof(struct sk_buff, len));
	/* s %w1,<data_len>(%b1) */
	EMIT4_DISP(0x5b000000, REG_W1, BPF_REG_1,
		   offsetof(struct sk_buff, data_len));
	/* stg %w1,ST_OFF_HLEN(%r0,%r15) */
	EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, REG_15, STK_OFF_HLEN);
	if (!(jit->seen & SEEN_REG_AX))
		/* lg %skb_data,data_off(%b1) */
		EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
			      BPF_REG_1, offsetof(struct sk_buff, data));
}

/*
 * Emit function prologue
 *
 * Save registers and create stack frame if necessary.
 * See stack frame layout desription in "bpf_jit.h"!
 */
static void bpf_jit_prologue(struct bpf_jit *jit)
{
	if (jit->seen & SEEN_TAIL_CALL) {
		/* xc STK_OFF_TCCNT(4,%r15),STK_OFF_TCCNT(%r15) */
		_EMIT6(0xd703f000 | STK_OFF_TCCNT, 0xf000 | STK_OFF_TCCNT);
	} else {
		/* j tail_call_start: NOP if no tail calls are used */
		EMIT4_PCREL(0xa7f40000, 6);
		_EMIT2(0);
	}
	/* Tail calls have to skip above initialization */
	jit->tail_call_start = jit->prg;
	/* Save registers */
	save_restore_regs(jit, REGS_SAVE);
	/* Setup literal pool */
	if (jit->seen & SEEN_LITERAL) {
		/* basr %r13,0 */
		EMIT2(0x0d00, REG_L, REG_0);
		jit->base_ip = jit->prg;
	}
	/* Setup stack and backchain */
	if (jit->seen & SEEN_STACK) {
		if (jit->seen & SEEN_FUNC)
			/* lgr %w1,%r15 (backchain) */
			EMIT4(0xb9040000, REG_W1, REG_15);
		/* la %bfp,STK_160_UNUSED(%r15) (BPF frame pointer) */
		EMIT4_DISP(0x41000000, BPF_REG_FP, REG_15, STK_160_UNUSED);
		/* aghi %r15,-STK_OFF */
		EMIT4_IMM(0xa70b0000, REG_15, -STK_OFF);
		if (jit->seen & SEEN_FUNC)
			/* stg %w1,152(%r15) (backchain) */
			EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0,
				      REG_15, 152);
	}
	if (jit->seen & SEEN_SKB)
		emit_load_skb_data_hlen(jit);
	if (jit->seen & SEEN_SKB_CHANGE)
		/* stg %b1,ST_OFF_SKBP(%r0,%r15) */
		EMIT6_DISP_LH(0xe3000000, 0x0024, BPF_REG_1, REG_0, REG_15,
			      STK_OFF_SKBP);
}

/*
 * Function epilogue
 */
static void bpf_jit_epilogue(struct bpf_jit *jit)
{
	/* Return 0 */
	if (jit->seen & SEEN_RET0) {
		jit->ret0_ip = jit->prg;
		/* lghi %b0,0 */
		EMIT4_IMM(0xa7090000, BPF_REG_0, 0);
	}
	jit->exit_ip = jit->prg;
	/* Load exit code: lgr %r2,%b0 */
	EMIT4(0xb9040000, REG_2, BPF_REG_0);
	/* Restore registers */
	save_restore_regs(jit, REGS_RESTORE);
	/* br %r14 */
	_EMIT2(0x07fe);
}

/*
 * Compile one eBPF instruction into s390x code
 *
 * NOTE: Use noinline because for gcov (-fprofile-arcs) gcc allocates a lot of
 * stack space for the large switch statement.
 */
static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i)
{
	struct bpf_insn *insn = &fp->insnsi[i];
	int jmp_off, last, insn_count = 1;
	unsigned int func_addr, mask;
	u32 dst_reg = insn->dst_reg;
	u32 src_reg = insn->src_reg;
	u32 *addrs = jit->addrs;
	s32 imm = insn->imm;
	s16 off = insn->off;

	if (dst_reg == BPF_REG_AX || src_reg == BPF_REG_AX)
		jit->seen |= SEEN_REG_AX;
	switch (insn->code) {
	/*
	 * BPF_MOV
	 */
	case BPF_ALU | BPF_MOV | BPF_X: /* dst = (u32) src */
		/* llgfr %dst,%src */
		EMIT4(0xb9160000, dst_reg, src_reg);
		break;
	case BPF_ALU64 | BPF_MOV | BPF_X: /* dst = src */
		/* lgr %dst,%src */
		EMIT4(0xb9040000, dst_reg, src_reg);
		break;
	case BPF_ALU | BPF_MOV | BPF_K: /* dst = (u32) imm */
		/* llilf %dst,imm */
		EMIT6_IMM(0xc00f0000, dst_reg, imm);
		break;
	case BPF_ALU64 | BPF_MOV | BPF_K: /* dst = imm */
		/* lgfi %dst,imm */
		EMIT6_IMM(0xc0010000, dst_reg, imm);
		break;
	/*
	 * BPF_LD 64
	 */
	case BPF_LD | BPF_IMM | BPF_DW: /* dst = (u64) imm */
	{
		/* 16 byte instruction that uses two 'struct bpf_insn' */
		u64 imm64;

		imm64 = (u64)(u32) insn[0].imm | ((u64)(u32) insn[1].imm) << 32;
		/* lg %dst,<d(imm)>(%l) */
		EMIT6_DISP_LH(0xe3000000, 0x0004, dst_reg, REG_0, REG_L,
			      EMIT_CONST_U64(imm64));
		insn_count = 2;
		break;
	}
	/*
	 * BPF_ADD
	 */
	case BPF_ALU | BPF_ADD | BPF_X: /* dst = (u32) dst + (u32) src */
		/* ar %dst,%src */
		EMIT2(0x1a00, dst_reg, src_reg);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_ADD | BPF_X: /* dst = dst + src */
		/* agr %dst,%src */
		EMIT4(0xb9080000, dst_reg, src_reg);
		break;
	case BPF_ALU | BPF_ADD | BPF_K: /* dst = (u32) dst + (u32) imm */
		if (!imm)
			break;
		/* alfi %dst,imm */
		EMIT6_IMM(0xc20b0000, dst_reg, imm);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_ADD | BPF_K: /* dst = dst + imm */
		if (!imm)
			break;
		/* agfi %dst,imm */
		EMIT6_IMM(0xc2080000, dst_reg, imm);
		break;
	/*
	 * BPF_SUB
	 */
	case BPF_ALU | BPF_SUB | BPF_X: /* dst = (u32) dst - (u32) src */
		/* sr %dst,%src */
		EMIT2(0x1b00, dst_reg, src_reg);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_SUB | BPF_X: /* dst = dst - src */
		/* sgr %dst,%src */
		EMIT4(0xb9090000, dst_reg, src_reg);
		break;
	case BPF_ALU | BPF_SUB | BPF_K: /* dst = (u32) dst - (u32) imm */
		if (!imm)
			break;
		/* alfi %dst,-imm */
		EMIT6_IMM(0xc20b0000, dst_reg, -imm);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_SUB | BPF_K: /* dst = dst - imm */
		if (!imm)
			break;
		/* agfi %dst,-imm */
		EMIT6_IMM(0xc2080000, dst_reg, -imm);
		break;
	/*
	 * BPF_MUL
	 */
	case BPF_ALU | BPF_MUL | BPF_X: /* dst = (u32) dst * (u32) src */
		/* msr %dst,%src */
		EMIT4(0xb2520000, dst_reg, src_reg);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_MUL | BPF_X: /* dst = dst * src */
		/* msgr %dst,%src */
		EMIT4(0xb90c0000, dst_reg, src_reg);
		break;
	case BPF_ALU | BPF_MUL | BPF_K: /* dst = (u32) dst * (u32) imm */
		if (imm == 1)
			break;
		/* msfi %r5,imm */
		EMIT6_IMM(0xc2010000, dst_reg, imm);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_MUL | BPF_K: /* dst = dst * imm */
		if (imm == 1)
			break;
		/* msgfi %dst,imm */
		EMIT6_IMM(0xc2000000, dst_reg, imm);
		break;
	/*
	 * BPF_DIV / BPF_MOD
	 */
	case BPF_ALU | BPF_DIV | BPF_X: /* dst = (u32) dst / (u32) src */
	case BPF_ALU | BPF_MOD | BPF_X: /* dst = (u32) dst % (u32) src */
	{
		int rc_reg = BPF_OP(insn->code) == BPF_DIV ? REG_W1 : REG_W0;

		jit->seen |= SEEN_RET0;
		/* ltr %src,%src (if src == 0 goto fail) */
		EMIT2(0x1200, src_reg, src_reg);
		/* jz <ret0> */
		EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
		/* lhi %w0,0 */
		EMIT4_IMM(0xa7080000, REG_W0, 0);
		/* lr %w1,%dst */
		EMIT2(0x1800, REG_W1, dst_reg);
		/* dlr %w0,%src */
		EMIT4(0xb9970000, REG_W0, src_reg);
		/* llgfr %dst,%rc */
		EMIT4(0xb9160000, dst_reg, rc_reg);
		break;
	}
	case BPF_ALU64 | BPF_DIV | BPF_X: /* dst = dst / src */
	case BPF_ALU64 | BPF_MOD | BPF_X: /* dst = dst % src */
	{
		int rc_reg = BPF_OP(insn->code) == BPF_DIV ? REG_W1 : REG_W0;

		jit->seen |= SEEN_RET0;
		/* ltgr %src,%src (if src == 0 goto fail) */
		EMIT4(0xb9020000, src_reg, src_reg);
		/* jz <ret0> */
		EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
		/* lghi %w0,0 */
		EMIT4_IMM(0xa7090000, REG_W0, 0);
		/* lgr %w1,%dst */
		EMIT4(0xb9040000, REG_W1, dst_reg);
		/* dlgr %w0,%dst */
		EMIT4(0xb9870000, REG_W0, src_reg);
		/* lgr %dst,%rc */
		EMIT4(0xb9040000, dst_reg, rc_reg);
		break;
	}
	case BPF_ALU | BPF_DIV | BPF_K: /* dst = (u32) dst / (u32) imm */
	case BPF_ALU | BPF_MOD | BPF_K: /* dst = (u32) dst % (u32) imm */
	{
		int rc_reg = BPF_OP(insn->code) == BPF_DIV ? REG_W1 : REG_W0;

		if (imm == 1) {
			if (BPF_OP(insn->code) == BPF_MOD)
				/* lhgi %dst,0 */
				EMIT4_IMM(0xa7090000, dst_reg, 0);
			break;
		}
		/* lhi %w0,0 */
		EMIT4_IMM(0xa7080000, REG_W0, 0);
		/* lr %w1,%dst */
		EMIT2(0x1800, REG_W1, dst_reg);
		/* dl %w0,<d(imm)>(%l) */
		EMIT6_DISP_LH(0xe3000000, 0x0097, REG_W0, REG_0, REG_L,
			      EMIT_CONST_U32(imm));
		/* llgfr %dst,%rc */
		EMIT4(0xb9160000, dst_reg, rc_reg);
		break;
	}
	case BPF_ALU64 | BPF_DIV | BPF_K: /* dst = dst / imm */
	case BPF_ALU64 | BPF_MOD | BPF_K: /* dst = dst % imm */
	{
		int rc_reg = BPF_OP(insn->code) == BPF_DIV ? REG_W1 : REG_W0;

		if (imm == 1) {
			if (BPF_OP(insn->code) == BPF_MOD)
				/* lhgi %dst,0 */
				EMIT4_IMM(0xa7090000, dst_reg, 0);
			break;
		}
		/* lghi %w0,0 */
		EMIT4_IMM(0xa7090000, REG_W0, 0);
		/* lgr %w1,%dst */
		EMIT4(0xb9040000, REG_W1, dst_reg);
		/* dlg %w0,<d(imm)>(%l) */
		EMIT6_DISP_LH(0xe3000000, 0x0087, REG_W0, REG_0, REG_L,
			      EMIT_CONST_U64(imm));
		/* lgr %dst,%rc */
		EMIT4(0xb9040000, dst_reg, rc_reg);
		break;
	}
	/*
	 * BPF_AND
	 */
	case BPF_ALU | BPF_AND | BPF_X: /* dst = (u32) dst & (u32) src */
		/* nr %dst,%src */
		EMIT2(0x1400, dst_reg, src_reg);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_AND | BPF_X: /* dst = dst & src */
		/* ngr %dst,%src */
		EMIT4(0xb9800000, dst_reg, src_reg);
		break;
	case BPF_ALU | BPF_AND | BPF_K: /* dst = (u32) dst & (u32) imm */
		/* nilf %dst,imm */
		EMIT6_IMM(0xc00b0000, dst_reg, imm);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_AND | BPF_K: /* dst = dst & imm */
		/* ng %dst,<d(imm)>(%l) */
		EMIT6_DISP_LH(0xe3000000, 0x0080, dst_reg, REG_0, REG_L,
			      EMIT_CONST_U64(imm));
		break;
	/*
	 * BPF_OR
	 */
	case BPF_ALU | BPF_OR | BPF_X: /* dst = (u32) dst | (u32) src */
		/* or %dst,%src */
		EMIT2(0x1600, dst_reg, src_reg);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_OR | BPF_X: /* dst = dst | src */
		/* ogr %dst,%src */
		EMIT4(0xb9810000, dst_reg, src_reg);
		break;
	case BPF_ALU | BPF_OR | BPF_K: /* dst = (u32) dst | (u32) imm */
		/* oilf %dst,imm */
		EMIT6_IMM(0xc00d0000, dst_reg, imm);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_OR | BPF_K: /* dst = dst | imm */
		/* og %dst,<d(imm)>(%l) */
		EMIT6_DISP_LH(0xe3000000, 0x0081, dst_reg, REG_0, REG_L,
			      EMIT_CONST_U64(imm));
		break;
	/*
	 * BPF_XOR
	 */
	case BPF_ALU | BPF_XOR | BPF_X: /* dst = (u32) dst ^ (u32) src */
		/* xr %dst,%src */
		EMIT2(0x1700, dst_reg, src_reg);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_XOR | BPF_X: /* dst = dst ^ src */
		/* xgr %dst,%src */
		EMIT4(0xb9820000, dst_reg, src_reg);
		break;
	case BPF_ALU | BPF_XOR | BPF_K: /* dst = (u32) dst ^ (u32) imm */
		if (!imm)
			break;
		/* xilf %dst,imm */
		EMIT6_IMM(0xc0070000, dst_reg, imm);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_XOR | BPF_K: /* dst = dst ^ imm */
		/* xg %dst,<d(imm)>(%l) */
		EMIT6_DISP_LH(0xe3000000, 0x0082, dst_reg, REG_0, REG_L,
			      EMIT_CONST_U64(imm));
		break;
	/*
	 * BPF_LSH
	 */
	case BPF_ALU | BPF_LSH | BPF_X: /* dst = (u32) dst << (u32) src */
		/* sll %dst,0(%src) */
		EMIT4_DISP(0x89000000, dst_reg, src_reg, 0);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_LSH | BPF_X: /* dst = dst << src */
		/* sllg %dst,%dst,0(%src) */
		EMIT6_DISP_LH(0xeb000000, 0x000d, dst_reg, dst_reg, src_reg, 0);
		break;
	case BPF_ALU | BPF_LSH | BPF_K: /* dst = (u32) dst << (u32) imm */
		if (imm == 0)
			break;
		/* sll %dst,imm(%r0) */
		EMIT4_DISP(0x89000000, dst_reg, REG_0, imm);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_LSH | BPF_K: /* dst = dst << imm */
		if (imm == 0)
			break;
		/* sllg %dst,%dst,imm(%r0) */
		EMIT6_DISP_LH(0xeb000000, 0x000d, dst_reg, dst_reg, REG_0, imm);
		break;
	/*
	 * BPF_RSH
	 */
	case BPF_ALU | BPF_RSH | BPF_X: /* dst = (u32) dst >> (u32) src */
		/* srl %dst,0(%src) */
		EMIT4_DISP(0x88000000, dst_reg, src_reg, 0);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_RSH | BPF_X: /* dst = dst >> src */
		/* srlg %dst,%dst,0(%src) */
		EMIT6_DISP_LH(0xeb000000, 0x000c, dst_reg, dst_reg, src_reg, 0);
		break;
	case BPF_ALU | BPF_RSH | BPF_K: /* dst = (u32) dst >> (u32) imm */
		if (imm == 0)
			break;
		/* srl %dst,imm(%r0) */
		EMIT4_DISP(0x88000000, dst_reg, REG_0, imm);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_RSH | BPF_K: /* dst = dst >> imm */
		if (imm == 0)
			break;
		/* srlg %dst,%dst,imm(%r0) */
		EMIT6_DISP_LH(0xeb000000, 0x000c, dst_reg, dst_reg, REG_0, imm);
		break;
	/*
	 * BPF_ARSH
	 */
	case BPF_ALU64 | BPF_ARSH | BPF_X: /* ((s64) dst) >>= src */
		/* srag %dst,%dst,0(%src) */
		EMIT6_DISP_LH(0xeb000000, 0x000a, dst_reg, dst_reg, src_reg, 0);
		break;
	case BPF_ALU64 | BPF_ARSH | BPF_K: /* ((s64) dst) >>= imm */
		if (imm == 0)
			break;
		/* srag %dst,%dst,imm(%r0) */
		EMIT6_DISP_LH(0xeb000000, 0x000a, dst_reg, dst_reg, REG_0, imm);
		break;
	/*
	 * BPF_NEG
	 */
	case BPF_ALU | BPF_NEG: /* dst = (u32) -dst */
		/* lcr %dst,%dst */
		EMIT2(0x1300, dst_reg, dst_reg);
		EMIT_ZERO(dst_reg);
		break;
	case BPF_ALU64 | BPF_NEG: /* dst = -dst */
		/* lcgr %dst,%dst */
		EMIT4(0xb9130000, dst_reg, dst_reg);
		break;
	/*
	 * BPF_FROM_BE/LE
	 */
	case BPF_ALU | BPF_END | BPF_FROM_BE:
		/* s390 is big endian, therefore only clear high order bytes */
		switch (imm) {
		case 16: /* dst = (u16) cpu_to_be16(dst) */
			/* llghr %dst,%dst */
			EMIT4(0xb9850000, dst_reg, dst_reg);
			break;
		case 32: /* dst = (u32) cpu_to_be32(dst) */
			/* llgfr %dst,%dst */
			EMIT4(0xb9160000, dst_reg, dst_reg);
			break;
		case 64: /* dst = (u64) cpu_to_be64(dst) */
			break;
		}
		break;
	case BPF_ALU | BPF_END | BPF_FROM_LE:
		switch (imm) {
		case 16: /* dst = (u16) cpu_to_le16(dst) */
			/* lrvr %dst,%dst */
			EMIT4(0xb91f0000, dst_reg, dst_reg);
			/* srl %dst,16(%r0) */
			EMIT4_DISP(0x88000000, dst_reg, REG_0, 16);
			/* llghr %dst,%dst */
			EMIT4(0xb9850000, dst_reg, dst_reg);
			break;
		case 32: /* dst = (u32) cpu_to_le32(dst) */
			/* lrvr %dst,%dst */
			EMIT4(0xb91f0000, dst_reg, dst_reg);
			/* llgfr %dst,%dst */
			EMIT4(0xb9160000, dst_reg, dst_reg);
			break;
		case 64: /* dst = (u64) cpu_to_le64(dst) */
			/* lrvgr %dst,%dst */
			EMIT4(0xb90f0000, dst_reg, dst_reg);
			break;
		}
		break;
	/*
	 * BPF_ST(X)
	 */
	case BPF_STX | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = src_reg */
		/* stcy %src,off(%dst) */
		EMIT6_DISP_LH(0xe3000000, 0x0072, src_reg, dst_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_STX | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = src */
		/* sthy %src,off(%dst) */
		EMIT6_DISP_LH(0xe3000000, 0x0070, src_reg, dst_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_STX | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = src */
		/* sty %src,off(%dst) */
		EMIT6_DISP_LH(0xe3000000, 0x0050, src_reg, dst_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_STX | BPF_MEM | BPF_DW: /* (u64 *)(dst + off) = src */
		/* stg %src,off(%dst) */
		EMIT6_DISP_LH(0xe3000000, 0x0024, src_reg, dst_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_ST | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = imm */
		/* lhi %w0,imm */
		EMIT4_IMM(0xa7080000, REG_W0, (u8) imm);
		/* stcy %w0,off(dst) */
		EMIT6_DISP_LH(0xe3000000, 0x0072, REG_W0, dst_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_ST | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = imm */
		/* lhi %w0,imm */
		EMIT4_IMM(0xa7080000, REG_W0, (u16) imm);
		/* sthy %w0,off(dst) */
		EMIT6_DISP_LH(0xe3000000, 0x0070, REG_W0, dst_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_ST | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = imm */
		/* llilf %w0,imm  */
		EMIT6_IMM(0xc00f0000, REG_W0, (u32) imm);
		/* sty %w0,off(%dst) */
		EMIT6_DISP_LH(0xe3000000, 0x0050, REG_W0, dst_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_ST | BPF_MEM | BPF_DW: /* *(u64 *)(dst + off) = imm */
		/* lgfi %w0,imm */
		EMIT6_IMM(0xc0010000, REG_W0, imm);
		/* stg %w0,off(%dst) */
		EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W0, dst_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	/*
	 * BPF_STX XADD (atomic_add)
	 */
	case BPF_STX | BPF_XADD | BPF_W: /* *(u32 *)(dst + off) += src */
		/* laal %w0,%src,off(%dst) */
		EMIT6_DISP_LH(0xeb000000, 0x00fa, REG_W0, src_reg,
			      dst_reg, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_STX | BPF_XADD | BPF_DW: /* *(u64 *)(dst + off) += src */
		/* laalg %w0,%src,off(%dst) */
		EMIT6_DISP_LH(0xeb000000, 0x00ea, REG_W0, src_reg,
			      dst_reg, off);
		jit->seen |= SEEN_MEM;
		break;
	/*
	 * BPF_LDX
	 */
	case BPF_LDX | BPF_MEM | BPF_B: /* dst = *(u8 *)(ul) (src + off) */
		/* llgc %dst,0(off,%src) */
		EMIT6_DISP_LH(0xe3000000, 0x0090, dst_reg, src_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_LDX | BPF_MEM | BPF_H: /* dst = *(u16 *)(ul) (src + off) */
		/* llgh %dst,0(off,%src) */
		EMIT6_DISP_LH(0xe3000000, 0x0091, dst_reg, src_reg, REG_0, off);
		jit->seen |= SEEN_MEM;
		break;
	case BPF_LDX | BPF_MEM | BPF_W: /* dst = *(u32 *)(ul) (src + off) */
		/* llgf %dst,off(%src) */
		jit->seen |= SEEN_MEM;
		EMIT6_DISP_LH(0xe3000000, 0x0016, dst_reg, src_reg, REG_0, off);
		break;
	case BPF_LDX | BPF_MEM | BPF_DW: /* dst = *(u64 *)(ul) (src + off) */
		/* lg %dst,0(off,%src) */
		jit->seen |= SEEN_MEM;
		EMIT6_DISP_LH(0xe3000000, 0x0004, dst_reg, src_reg, REG_0, off);
		break;
	/*
	 * BPF_JMP / CALL
	 */
	case BPF_JMP | BPF_CALL:
	{
		/*
		 * b0 = (__bpf_call_base + imm)(b1, b2, b3, b4, b5)
		 */
		const u64 func = (u64)__bpf_call_base + imm;

		REG_SET_SEEN(BPF_REG_5);
		jit->seen |= SEEN_FUNC;
		/* lg %w1,<d(imm)>(%l) */
		EMIT6_DISP_LH(0xe3000000, 0x0004, REG_W1, REG_0, REG_L,
			      EMIT_CONST_U64(func));
		/* basr %r14,%w1 */
		EMIT2(0x0d00, REG_14, REG_W1);
		/* lgr %b0,%r2: load return value into %b0 */
		EMIT4(0xb9040000, BPF_REG_0, REG_2);
		if (bpf_helper_changes_pkt_data((void *)func)) {
			jit->seen |= SEEN_SKB_CHANGE;
			/* lg %b1,ST_OFF_SKBP(%r15) */
			EMIT6_DISP_LH(0xe3000000, 0x0004, BPF_REG_1, REG_0,
				      REG_15, STK_OFF_SKBP);
			emit_load_skb_data_hlen(jit);
		}
		break;
	}
	case BPF_JMP | BPF_CALL | BPF_X:
		/*
		 * Implicit input:
		 *  B1: pointer to ctx
		 *  B2: pointer to bpf_array
		 *  B3: index in bpf_array
		 */
		jit->seen |= SEEN_TAIL_CALL;

		/*
		 * if (index >= array->map.max_entries)
		 *         goto out;
		 */

		/* llgf %w1,map.max_entries(%b2) */
		EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_2,
			      offsetof(struct bpf_array, map.max_entries));
		/* clgrj %b3,%w1,0xa,label0: if %b3 >= %w1 goto out */
		EMIT6_PCREL_LABEL(0xec000000, 0x0065, BPF_REG_3,
				  REG_W1, 0, 0xa);

		/*
		 * if (tail_call_cnt++ > MAX_TAIL_CALL_CNT)
		 *         goto out;
		 */

		if (jit->seen & SEEN_STACK)
			off = STK_OFF_TCCNT + STK_OFF;
		else
			off = STK_OFF_TCCNT;
		/* lhi %w0,1 */
		EMIT4_IMM(0xa7080000, REG_W0, 1);
		/* laal %w1,%w0,off(%r15) */
		EMIT6_DISP_LH(0xeb000000, 0x00fa, REG_W1, REG_W0, REG_15, off);
		/* clij %w1,MAX_TAIL_CALL_CNT,0x2,label0 */
		EMIT6_PCREL_IMM_LABEL(0xec000000, 0x007f, REG_W1,
				      MAX_TAIL_CALL_CNT, 0, 0x2);

		/*
		 * prog = array->ptrs[index];
		 * if (prog == NULL)
		 *         goto out;
		 */

		/* sllg %r1,%b3,3: %r1 = index * 8 */
		EMIT6_DISP_LH(0xeb000000, 0x000d, REG_1, BPF_REG_3, REG_0, 3);
		/* lg %r1,prog(%b2,%r1) */
		EMIT6_DISP_LH(0xe3000000, 0x0004, REG_1, BPF_REG_2,
			      REG_1, offsetof(struct bpf_array, ptrs));
		/* clgij %r1,0,0x8,label0 */
		EMIT6_PCREL_IMM_LABEL(0xec000000, 0x007d, REG_1, 0, 0, 0x8);

		/*
		 * Restore registers before calling function
		 */
		save_restore_regs(jit, REGS_RESTORE);

		/*
		 * goto *(prog->bpf_func + tail_call_start);
		 */

		/* lg %r1,bpf_func(%r1) */
		EMIT6_DISP_LH(0xe3000000, 0x0004, REG_1, REG_1, REG_0,
			      offsetof(struct bpf_prog, bpf_func));
		/* bc 0xf,tail_call_start(%r1) */
		_EMIT4(0x47f01000 + jit->tail_call_start);
		/* out: */
		jit->labels[0] = jit->prg;
		break;
	case BPF_JMP | BPF_EXIT: /* return b0 */
		last = (i == fp->len - 1) ? 1 : 0;
		if (last && !(jit->seen & SEEN_RET0))
			break;
		/* j <exit> */
		EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
		break;
	/*
	 * Branch relative (number of skipped instructions) to offset on
	 * condition.
	 *
	 * Condition code to mask mapping:
	 *
	 * CC | Description	   | Mask
	 * ------------------------------
	 * 0  | Operands equal	   |	8
	 * 1  | First operand low  |	4
	 * 2  | First operand high |	2
	 * 3  | Unused		   |	1
	 *
	 * For s390x relative branches: ip = ip + off_bytes
	 * For BPF relative branches:	insn = insn + off_insns + 1
	 *
	 * For example for s390x with offset 0 we jump to the branch
	 * instruction itself (loop) and for BPF with offset 0 we
	 * branch to the instruction behind the branch.
	 */
	case BPF_JMP | BPF_JA: /* if (true) */
		mask = 0xf000; /* j */
		goto branch_oc;
	case BPF_JMP | BPF_JSGT | BPF_K: /* ((s64) dst > (s64) imm) */
		mask = 0x2000; /* jh */
		goto branch_ks;
	case BPF_JMP | BPF_JSGE | BPF_K: /* ((s64) dst >= (s64) imm) */
		mask = 0xa000; /* jhe */
		goto branch_ks;
	case BPF_JMP | BPF_JGT | BPF_K: /* (dst_reg > imm) */
		mask = 0x2000; /* jh */
		goto branch_ku;
	case BPF_JMP | BPF_JGE | BPF_K: /* (dst_reg >= imm) */
		mask = 0xa000; /* jhe */
		goto branch_ku;
	case BPF_JMP | BPF_JNE | BPF_K: /* (dst_reg != imm) */
		mask = 0x7000; /* jne */
		goto branch_ku;
	case BPF_JMP | BPF_JEQ | BPF_K: /* (dst_reg == imm) */
		mask = 0x8000; /* je */
		goto branch_ku;
	case BPF_JMP | BPF_JSET | BPF_K: /* (dst_reg & imm) */
		mask = 0x7000; /* jnz */
		/* lgfi %w1,imm (load sign extend imm) */
		EMIT6_IMM(0xc0010000, REG_W1, imm);
		/* ngr %w1,%dst */
		EMIT4(0xb9800000, REG_W1, dst_reg);
		goto branch_oc;

	case BPF_JMP | BPF_JSGT | BPF_X: /* ((s64) dst > (s64) src) */
		mask = 0x2000; /* jh */
		goto branch_xs;
	case BPF_JMP | BPF_JSGE | BPF_X: /* ((s64) dst >= (s64) src) */
		mask = 0xa000; /* jhe */
		goto branch_xs;
	case BPF_JMP | BPF_JGT | BPF_X: /* (dst > src) */
		mask = 0x2000; /* jh */
		goto branch_xu;
	case BPF_JMP | BPF_JGE | BPF_X: /* (dst >= src) */
		mask = 0xa000; /* jhe */
		goto branch_xu;
	case BPF_JMP | BPF_JNE | BPF_X: /* (dst != src) */
		mask = 0x7000; /* jne */
		goto branch_xu;
	case BPF_JMP | BPF_JEQ | BPF_X: /* (dst == src) */
		mask = 0x8000; /* je */
		goto branch_xu;
	case BPF_JMP | BPF_JSET | BPF_X: /* (dst & src) */
		mask = 0x7000; /* jnz */
		/* ngrk %w1,%dst,%src */
		EMIT4_RRF(0xb9e40000, REG_W1, dst_reg, src_reg);
		goto branch_oc;
branch_ks:
		/* lgfi %w1,imm (load sign extend imm) */
		EMIT6_IMM(0xc0010000, REG_W1, imm);
		/* cgrj %dst,%w1,mask,off */
		EMIT6_PCREL(0xec000000, 0x0064, dst_reg, REG_W1, i, off, mask);
		break;
branch_ku:
		/* lgfi %w1,imm (load sign extend imm) */
		EMIT6_IMM(0xc0010000, REG_W1, imm);
		/* clgrj %dst,%w1,mask,off */
		EMIT6_PCREL(0xec000000, 0x0065, dst_reg, REG_W1, i, off, mask);
		break;
branch_xs:
		/* cgrj %dst,%src,mask,off */
		EMIT6_PCREL(0xec000000, 0x0064, dst_reg, src_reg, i, off, mask);
		break;
branch_xu:
		/* clgrj %dst,%src,mask,off */
		EMIT6_PCREL(0xec000000, 0x0065, dst_reg, src_reg, i, off, mask);
		break;
branch_oc:
		/* brc mask,jmp_off (branch instruction needs 4 bytes) */
		jmp_off = addrs[i + off + 1] - (addrs[i + 1] - 4);
		EMIT4_PCREL(0xa7040000 | mask << 8, jmp_off);
		break;
	/*
	 * BPF_LD
	 */
	case BPF_LD | BPF_ABS | BPF_B: /* b0 = *(u8 *) (skb->data+imm) */
	case BPF_LD | BPF_IND | BPF_B: /* b0 = *(u8 *) (skb->data+imm+src) */
		if ((BPF_MODE(insn->code) == BPF_ABS) && (imm >= 0))
			func_addr = __pa(sk_load_byte_pos);
		else
			func_addr = __pa(sk_load_byte);
		goto call_fn;
	case BPF_LD | BPF_ABS | BPF_H: /* b0 = *(u16 *) (skb->data+imm) */
	case BPF_LD | BPF_IND | BPF_H: /* b0 = *(u16 *) (skb->data+imm+src) */
		if ((BPF_MODE(insn->code) == BPF_ABS) && (imm >= 0))
			func_addr = __pa(sk_load_half_pos);
		else
			func_addr = __pa(sk_load_half);
		goto call_fn;
	case BPF_LD | BPF_ABS | BPF_W: /* b0 = *(u32 *) (skb->data+imm) */
	case BPF_LD | BPF_IND | BPF_W: /* b0 = *(u32 *) (skb->data+imm+src) */
		if ((BPF_MODE(insn->code) == BPF_ABS) && (imm >= 0))
			func_addr = __pa(sk_load_word_pos);
		else
			func_addr = __pa(sk_load_word);
		goto call_fn;
call_fn:
		jit->seen |= SEEN_SKB | SEEN_RET0 | SEEN_FUNC;
		REG_SET_SEEN(REG_14); /* Return address of possible func call */

		/*
		 * Implicit input:
		 *  BPF_REG_6	 (R7) : skb pointer
		 *  REG_SKB_DATA (R12): skb data pointer (if no BPF_REG_AX)
		 *
		 * Calculated input:
		 *  BPF_REG_2	 (R3) : offset of byte(s) to fetch in skb
		 *  BPF_REG_5	 (R6) : return address
		 *
		 * Output:
		 *  BPF_REG_0	 (R14): data read from skb
		 *
		 * Scratch registers (BPF_REG_1-5)
		 */

		/* Call function: llilf %w1,func_addr  */
		EMIT6_IMM(0xc00f0000, REG_W1, func_addr);

		/* Offset: lgfi %b2,imm */
		EMIT6_IMM(0xc0010000, BPF_REG_2, imm);
		if (BPF_MODE(insn->code) == BPF_IND)
			/* agfr %b2,%src (%src is s32 here) */
			EMIT4(0xb9180000, BPF_REG_2, src_reg);

		/* Reload REG_SKB_DATA if BPF_REG_AX is used */
		if (jit->seen & SEEN_REG_AX)
			/* lg %skb_data,data_off(%b6) */
			EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
				      BPF_REG_6, offsetof(struct sk_buff, data));
		/* basr %b5,%w1 (%b5 is call saved) */
		EMIT2(0x0d00, BPF_REG_5, REG_W1);

		/*
		 * Note: For fast access we jump directly after the
		 * jnz instruction from bpf_jit.S
		 */
		/* jnz <ret0> */
		EMIT4_PCREL(0xa7740000, jit->ret0_ip - jit->prg);
		break;
	default: /* too complex, give up */
		pr_err("Unknown opcode %02x\n", insn->code);
		return -1;
	}
	return insn_count;
}

/*
 * Compile eBPF program into s390x code
 */
static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp)
{
	int i, insn_count;

	jit->lit = jit->lit_start;
	jit->prg = 0;

	bpf_jit_prologue(jit);
	for (i = 0; i < fp->len; i += insn_count) {
		insn_count = bpf_jit_insn(jit, fp, i);
		if (insn_count < 0)
			return -1;
		jit->addrs[i + 1] = jit->prg; /* Next instruction address */
	}
	bpf_jit_epilogue(jit);

	jit->lit_start = jit->prg;
	jit->size = jit->lit;
	jit->size_prg = jit->prg;
	return 0;
}

/*
 * Classic BPF function stub. BPF programs will be converted into
 * eBPF and then bpf_int_jit_compile() will be called.
 */
void bpf_jit_compile(struct bpf_prog *fp)
{
}

/*
 * Compile eBPF program "fp"
 */
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
{
	struct bpf_prog *tmp, *orig_fp = fp;
	struct bpf_binary_header *header;
	bool tmp_blinded = false;
	struct bpf_jit jit;
	int pass;

	if (!bpf_jit_enable)
		return orig_fp;

	tmp = bpf_jit_blind_constants(fp);
	/*
	 * If blinding was requested and we failed during blinding,
	 * we must fall back to the interpreter.
	 */
	if (IS_ERR(tmp))
		return orig_fp;
	if (tmp != fp) {
		tmp_blinded = true;
		fp = tmp;
	}

	memset(&jit, 0, sizeof(jit));
	jit.addrs = kcalloc(fp->len + 1, sizeof(*jit.addrs), GFP_KERNEL);
	if (jit.addrs == NULL) {
		fp = orig_fp;
		goto out;
	}
	/*
	 * Three initial passes:
	 *   - 1/2: Determine clobbered registers
	 *   - 3:   Calculate program size and addrs arrray
	 */
	for (pass = 1; pass <= 3; pass++) {
		if (bpf_jit_prog(&jit, fp)) {
			fp = orig_fp;
			goto free_addrs;
		}
	}
	/*
	 * Final pass: Allocate and generate program
	 */
	if (jit.size >= BPF_SIZE_MAX) {
		fp = orig_fp;
		goto free_addrs;
	}
	header = bpf_jit_binary_alloc(jit.size, &jit.prg_buf, 2, jit_fill_hole);
	if (!header) {
		fp = orig_fp;
		goto free_addrs;
	}
	if (bpf_jit_prog(&jit, fp)) {
		fp = orig_fp;
		goto free_addrs;
	}
	if (bpf_jit_enable > 1) {
		bpf_jit_dump(fp->len, jit.size, pass, jit.prg_buf);
		if (jit.prg_buf)
			print_fn_code(jit.prg_buf, jit.size_prg);
	}
	if (jit.prg_buf) {
		set_memory_ro((unsigned long)header, header->pages);
		fp->bpf_func = (void *) jit.prg_buf;
		fp->jited = 1;
	}
free_addrs:
	kfree(jit.addrs);
out:
	if (tmp_blinded)
		bpf_jit_prog_release_other(fp, fp == orig_fp ?
					   tmp : orig_fp);
	return fp;
}

/*
 * Free eBPF program
 */
void bpf_jit_free(struct bpf_prog *fp)
{
	unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
	struct bpf_binary_header *header = (void *)addr;

	if (!fp->jited)
		goto free_filter;

	set_memory_rw(addr, header->pages);
	bpf_jit_binary_free(header);

free_filter:
	bpf_prog_unlock_free(fp);
}