summaryrefslogtreecommitdiffstats
path: root/arch/riscv/kernel/module.c
blob: 5e5a82644451e16d8bdfe229e2ce89b4c389c31e (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 *  Copyright (C) 2017 Zihao Yu
 */

#include <linux/elf.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/hashtable.h>
#include <linux/kernel.h>
#include <linux/log2.h>
#include <linux/moduleloader.h>
#include <linux/vmalloc.h>
#include <linux/sizes.h>
#include <linux/pgtable.h>
#include <asm/alternative.h>
#include <asm/sections.h>

struct used_bucket {
	struct list_head head;
	struct hlist_head *bucket;
};

struct relocation_head {
	struct hlist_node node;
	struct list_head *rel_entry;
	void *location;
};

struct relocation_entry {
	struct list_head head;
	Elf_Addr value;
	unsigned int type;
};

struct relocation_handlers {
	int (*reloc_handler)(struct module *me, void *location, Elf_Addr v);
	int (*accumulate_handler)(struct module *me, void *location,
				  long buffer);
};

/*
 * The auipc+jalr instruction pair can reach any PC-relative offset
 * in the range [-2^31 - 2^11, 2^31 - 2^11)
 */
static bool riscv_insn_valid_32bit_offset(ptrdiff_t val)
{
#ifdef CONFIG_32BIT
	return true;
#else
	return (-(1L << 31) - (1L << 11)) <= val && val < ((1L << 31) - (1L << 11));
#endif
}

static int riscv_insn_rmw(void *location, u32 keep, u32 set)
{
	__le16 *parcel = location;
	u32 insn = (u32)le16_to_cpu(parcel[0]) | (u32)le16_to_cpu(parcel[1]) << 16;

	insn &= keep;
	insn |= set;

	parcel[0] = cpu_to_le16(insn);
	parcel[1] = cpu_to_le16(insn >> 16);
	return 0;
}

static int riscv_insn_rvc_rmw(void *location, u16 keep, u16 set)
{
	__le16 *parcel = location;
	u16 insn = le16_to_cpu(*parcel);

	insn &= keep;
	insn |= set;

	*parcel = cpu_to_le16(insn);
	return 0;
}

static int apply_r_riscv_32_rela(struct module *me, void *location, Elf_Addr v)
{
	if (v != (u32)v) {
		pr_err("%s: value %016llx out of range for 32-bit field\n",
		       me->name, (long long)v);
		return -EINVAL;
	}
	*(u32 *)location = v;
	return 0;
}

static int apply_r_riscv_64_rela(struct module *me, void *location, Elf_Addr v)
{
	*(u64 *)location = v;
	return 0;
}

static int apply_r_riscv_branch_rela(struct module *me, void *location,
				     Elf_Addr v)
{
	ptrdiff_t offset = (void *)v - location;
	u32 imm12 = (offset & 0x1000) << (31 - 12);
	u32 imm11 = (offset & 0x800) >> (11 - 7);
	u32 imm10_5 = (offset & 0x7e0) << (30 - 10);
	u32 imm4_1 = (offset & 0x1e) << (11 - 4);

	return riscv_insn_rmw(location, 0x1fff07f, imm12 | imm11 | imm10_5 | imm4_1);
}

static int apply_r_riscv_jal_rela(struct module *me, void *location,
				  Elf_Addr v)
{
	ptrdiff_t offset = (void *)v - location;
	u32 imm20 = (offset & 0x100000) << (31 - 20);
	u32 imm19_12 = (offset & 0xff000);
	u32 imm11 = (offset & 0x800) << (20 - 11);
	u32 imm10_1 = (offset & 0x7fe) << (30 - 10);

	return riscv_insn_rmw(location, 0xfff, imm20 | imm19_12 | imm11 | imm10_1);
}

static int apply_r_riscv_rvc_branch_rela(struct module *me, void *location,
					 Elf_Addr v)
{
	ptrdiff_t offset = (void *)v - location;
	u16 imm8 = (offset & 0x100) << (12 - 8);
	u16 imm7_6 = (offset & 0xc0) >> (6 - 5);
	u16 imm5 = (offset & 0x20) >> (5 - 2);
	u16 imm4_3 = (offset & 0x18) << (12 - 5);
	u16 imm2_1 = (offset & 0x6) << (12 - 10);

	return riscv_insn_rvc_rmw(location, 0xe383,
			imm8 | imm7_6 | imm5 | imm4_3 | imm2_1);
}

static int apply_r_riscv_rvc_jump_rela(struct module *me, void *location,
				       Elf_Addr v)
{
	ptrdiff_t offset = (void *)v - location;
	u16 imm11 = (offset & 0x800) << (12 - 11);
	u16 imm10 = (offset & 0x400) >> (10 - 8);
	u16 imm9_8 = (offset & 0x300) << (12 - 11);
	u16 imm7 = (offset & 0x80) >> (7 - 6);
	u16 imm6 = (offset & 0x40) << (12 - 11);
	u16 imm5 = (offset & 0x20) >> (5 - 2);
	u16 imm4 = (offset & 0x10) << (12 - 5);
	u16 imm3_1 = (offset & 0xe) << (12 - 10);

	return riscv_insn_rvc_rmw(location, 0xe003,
			imm11 | imm10 | imm9_8 | imm7 | imm6 | imm5 | imm4 | imm3_1);
}

static int apply_r_riscv_pcrel_hi20_rela(struct module *me, void *location,
					 Elf_Addr v)
{
	ptrdiff_t offset = (void *)v - location;

	if (!riscv_insn_valid_32bit_offset(offset)) {
		pr_err(
		  "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
		  me->name, (long long)v, location);
		return -EINVAL;
	}

	return riscv_insn_rmw(location, 0xfff, (offset + 0x800) & 0xfffff000);
}

static int apply_r_riscv_pcrel_lo12_i_rela(struct module *me, void *location,
					   Elf_Addr v)
{
	/*
	 * v is the lo12 value to fill. It is calculated before calling this
	 * handler.
	 */
	return riscv_insn_rmw(location, 0xfffff, (v & 0xfff) << 20);
}

static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, void *location,
					   Elf_Addr v)
{
	/*
	 * v is the lo12 value to fill. It is calculated before calling this
	 * handler.
	 */
	u32 imm11_5 = (v & 0xfe0) << (31 - 11);
	u32 imm4_0 = (v & 0x1f) << (11 - 4);

	return riscv_insn_rmw(location, 0x1fff07f, imm11_5 | imm4_0);
}

static int apply_r_riscv_hi20_rela(struct module *me, void *location,
				   Elf_Addr v)
{
	if (IS_ENABLED(CONFIG_CMODEL_MEDLOW)) {
		pr_err(
		  "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
		  me->name, (long long)v, location);
		return -EINVAL;
	}

	return riscv_insn_rmw(location, 0xfff, ((s32)v + 0x800) & 0xfffff000);
}

static int apply_r_riscv_lo12_i_rela(struct module *me, void *location,
				     Elf_Addr v)
{
	/* Skip medlow checking because of filtering by HI20 already */
	s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
	s32 lo12 = ((s32)v - hi20);

	return riscv_insn_rmw(location, 0xfffff, (lo12 & 0xfff) << 20);
}

static int apply_r_riscv_lo12_s_rela(struct module *me, void *location,
				     Elf_Addr v)
{
	/* Skip medlow checking because of filtering by HI20 already */
	s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
	s32 lo12 = ((s32)v - hi20);
	u32 imm11_5 = (lo12 & 0xfe0) << (31 - 11);
	u32 imm4_0 = (lo12 & 0x1f) << (11 - 4);

	return riscv_insn_rmw(location, 0x1fff07f, imm11_5 | imm4_0);
}

static int apply_r_riscv_got_hi20_rela(struct module *me, void *location,
				       Elf_Addr v)
{
	ptrdiff_t offset = (void *)v - location;

	/* Always emit the got entry */
	if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
		offset = (void *)module_emit_got_entry(me, v) - location;
	} else {
		pr_err(
		  "%s: can not generate the GOT entry for symbol = %016llx from PC = %p\n",
		  me->name, (long long)v, location);
		return -EINVAL;
	}

	return riscv_insn_rmw(location, 0xfff, (offset + 0x800) & 0xfffff000);
}

static int apply_r_riscv_call_plt_rela(struct module *me, void *location,
				       Elf_Addr v)
{
	ptrdiff_t offset = (void *)v - location;
	u32 hi20, lo12;

	if (!riscv_insn_valid_32bit_offset(offset)) {
		/* Only emit the plt entry if offset over 32-bit range */
		if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
			offset = (void *)module_emit_plt_entry(me, v) - location;
		} else {
			pr_err(
			  "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
			  me->name, (long long)v, location);
			return -EINVAL;
		}
	}

	hi20 = (offset + 0x800) & 0xfffff000;
	lo12 = (offset - hi20) & 0xfff;
	riscv_insn_rmw(location, 0xfff, hi20);
	return riscv_insn_rmw(location + 4, 0xfffff, lo12 << 20);
}

static int apply_r_riscv_call_rela(struct module *me, void *location,
				   Elf_Addr v)
{
	ptrdiff_t offset = (void *)v - location;
	u32 hi20, lo12;

	if (!riscv_insn_valid_32bit_offset(offset)) {
		pr_err(
		  "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
		  me->name, (long long)v, location);
		return -EINVAL;
	}

	hi20 = (offset + 0x800) & 0xfffff000;
	lo12 = (offset - hi20) & 0xfff;
	riscv_insn_rmw(location, 0xfff, hi20);
	return riscv_insn_rmw(location + 4, 0xfffff, lo12 << 20);
}

static int apply_r_riscv_relax_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	return 0;
}

static int apply_r_riscv_align_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	pr_err(
	  "%s: The unexpected relocation type 'R_RISCV_ALIGN' from PC = %p\n",
	  me->name, location);
	return -EINVAL;
}

static int apply_r_riscv_add8_rela(struct module *me, void *location, Elf_Addr v)
{
	*(u8 *)location += (u8)v;
	return 0;
}

static int apply_r_riscv_add16_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	*(u16 *)location += (u16)v;
	return 0;
}

static int apply_r_riscv_add32_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	*(u32 *)location += (u32)v;
	return 0;
}

static int apply_r_riscv_add64_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	*(u64 *)location += (u64)v;
	return 0;
}

static int apply_r_riscv_sub8_rela(struct module *me, void *location, Elf_Addr v)
{
	*(u8 *)location -= (u8)v;
	return 0;
}

static int apply_r_riscv_sub16_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	*(u16 *)location -= (u16)v;
	return 0;
}

static int apply_r_riscv_sub32_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	*(u32 *)location -= (u32)v;
	return 0;
}

static int apply_r_riscv_sub64_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	*(u64 *)location -= (u64)v;
	return 0;
}

static int dynamic_linking_not_supported(struct module *me, void *location,
					 Elf_Addr v)
{
	pr_err("%s: Dynamic linking not supported in kernel modules PC = %p\n",
	       me->name, location);
	return -EINVAL;
}

static int tls_not_supported(struct module *me, void *location, Elf_Addr v)
{
	pr_err("%s: Thread local storage not supported in kernel modules PC = %p\n",
	       me->name, location);
	return -EINVAL;
}

static int apply_r_riscv_sub6_rela(struct module *me, void *location, Elf_Addr v)
{
	u8 *byte = location;
	u8 value = v;

	*byte = (*byte - (value & 0x3f)) & 0x3f;
	return 0;
}

static int apply_r_riscv_set6_rela(struct module *me, void *location, Elf_Addr v)
{
	u8 *byte = location;
	u8 value = v;

	*byte = (*byte & 0xc0) | (value & 0x3f);
	return 0;
}

static int apply_r_riscv_set8_rela(struct module *me, void *location, Elf_Addr v)
{
	*(u8 *)location = (u8)v;
	return 0;
}

static int apply_r_riscv_set16_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	*(u16 *)location = (u16)v;
	return 0;
}

static int apply_r_riscv_set32_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	*(u32 *)location = (u32)v;
	return 0;
}

static int apply_r_riscv_32_pcrel_rela(struct module *me, void *location,
				       Elf_Addr v)
{
	*(u32 *)location = v - (uintptr_t)location;
	return 0;
}

static int apply_r_riscv_plt32_rela(struct module *me, void *location,
				    Elf_Addr v)
{
	ptrdiff_t offset = (void *)v - location;

	if (!riscv_insn_valid_32bit_offset(offset)) {
		/* Only emit the plt entry if offset over 32-bit range */
		if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
			offset = (void *)module_emit_plt_entry(me, v) - location;
		} else {
			pr_err("%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
			       me->name, (long long)v, location);
			return -EINVAL;
		}
	}

	*(u32 *)location = (u32)offset;
	return 0;
}

static int apply_r_riscv_set_uleb128(struct module *me, void *location, Elf_Addr v)
{
	*(long *)location = v;
	return 0;
}

static int apply_r_riscv_sub_uleb128(struct module *me, void *location, Elf_Addr v)
{
	*(long *)location -= v;
	return 0;
}

static int apply_6_bit_accumulation(struct module *me, void *location, long buffer)
{
	u8 *byte = location;
	u8 value = buffer;

	if (buffer > 0x3f) {
		pr_err("%s: value %ld out of range for 6-bit relocation.\n",
		       me->name, buffer);
		return -EINVAL;
	}

	*byte = (*byte & 0xc0) | (value & 0x3f);
	return 0;
}

static int apply_8_bit_accumulation(struct module *me, void *location, long buffer)
{
	if (buffer > U8_MAX) {
		pr_err("%s: value %ld out of range for 8-bit relocation.\n",
		       me->name, buffer);
		return -EINVAL;
	}
	*(u8 *)location = (u8)buffer;
	return 0;
}

static int apply_16_bit_accumulation(struct module *me, void *location, long buffer)
{
	if (buffer > U16_MAX) {
		pr_err("%s: value %ld out of range for 16-bit relocation.\n",
		       me->name, buffer);
		return -EINVAL;
	}
	*(u16 *)location = (u16)buffer;
	return 0;
}

static int apply_32_bit_accumulation(struct module *me, void *location, long buffer)
{
	if (buffer > U32_MAX) {
		pr_err("%s: value %ld out of range for 32-bit relocation.\n",
		       me->name, buffer);
		return -EINVAL;
	}
	*(u32 *)location = (u32)buffer;
	return 0;
}

static int apply_64_bit_accumulation(struct module *me, void *location, long buffer)
{
	*(u64 *)location = (u64)buffer;
	return 0;
}

static int apply_uleb128_accumulation(struct module *me, void *location, long buffer)
{
	/*
	 * ULEB128 is a variable length encoding. Encode the buffer into
	 * the ULEB128 data format.
	 */
	u8 *p = location;

	while (buffer != 0) {
		u8 value = buffer & 0x7f;

		buffer >>= 7;
		value |= (!!buffer) << 7;

		*p++ = value;
	}
	return 0;
}

/*
 * Relocations defined in the riscv-elf-psabi-doc.
 * This handles static linking only.
 */
static const struct relocation_handlers reloc_handlers[] = {
	[R_RISCV_32]		= { .reloc_handler = apply_r_riscv_32_rela },
	[R_RISCV_64]		= { .reloc_handler = apply_r_riscv_64_rela },
	[R_RISCV_RELATIVE]	= { .reloc_handler = dynamic_linking_not_supported },
	[R_RISCV_COPY]		= { .reloc_handler = dynamic_linking_not_supported },
	[R_RISCV_JUMP_SLOT]	= { .reloc_handler = dynamic_linking_not_supported },
	[R_RISCV_TLS_DTPMOD32]	= { .reloc_handler = dynamic_linking_not_supported },
	[R_RISCV_TLS_DTPMOD64]	= { .reloc_handler = dynamic_linking_not_supported },
	[R_RISCV_TLS_DTPREL32]	= { .reloc_handler = dynamic_linking_not_supported },
	[R_RISCV_TLS_DTPREL64]	= { .reloc_handler = dynamic_linking_not_supported },
	[R_RISCV_TLS_TPREL32]	= { .reloc_handler = dynamic_linking_not_supported },
	[R_RISCV_TLS_TPREL64]	= { .reloc_handler = dynamic_linking_not_supported },
	/* 12-15 undefined */
	[R_RISCV_BRANCH]	= { .reloc_handler = apply_r_riscv_branch_rela },
	[R_RISCV_JAL]		= { .reloc_handler = apply_r_riscv_jal_rela },
	[R_RISCV_CALL]		= { .reloc_handler = apply_r_riscv_call_rela },
	[R_RISCV_CALL_PLT]	= { .reloc_handler = apply_r_riscv_call_plt_rela },
	[R_RISCV_GOT_HI20]	= { .reloc_handler = apply_r_riscv_got_hi20_rela },
	[R_RISCV_TLS_GOT_HI20]	= { .reloc_handler = tls_not_supported },
	[R_RISCV_TLS_GD_HI20]	= { .reloc_handler = tls_not_supported },
	[R_RISCV_PCREL_HI20]	= { .reloc_handler = apply_r_riscv_pcrel_hi20_rela },
	[R_RISCV_PCREL_LO12_I]	= { .reloc_handler = apply_r_riscv_pcrel_lo12_i_rela },
	[R_RISCV_PCREL_LO12_S]	= { .reloc_handler = apply_r_riscv_pcrel_lo12_s_rela },
	[R_RISCV_HI20]		= { .reloc_handler = apply_r_riscv_hi20_rela },
	[R_RISCV_LO12_I]	= { .reloc_handler = apply_r_riscv_lo12_i_rela },
	[R_RISCV_LO12_S]	= { .reloc_handler = apply_r_riscv_lo12_s_rela },
	[R_RISCV_TPREL_HI20]	= { .reloc_handler = tls_not_supported },
	[R_RISCV_TPREL_LO12_I]	= { .reloc_handler = tls_not_supported },
	[R_RISCV_TPREL_LO12_S]	= { .reloc_handler = tls_not_supported },
	[R_RISCV_TPREL_ADD]	= { .reloc_handler = tls_not_supported },
	[R_RISCV_ADD8]		= { .reloc_handler = apply_r_riscv_add8_rela,
				    .accumulate_handler = apply_8_bit_accumulation },
	[R_RISCV_ADD16]		= { .reloc_handler = apply_r_riscv_add16_rela,
				    .accumulate_handler = apply_16_bit_accumulation },
	[R_RISCV_ADD32]		= { .reloc_handler = apply_r_riscv_add32_rela,
				    .accumulate_handler = apply_32_bit_accumulation },
	[R_RISCV_ADD64]		= { .reloc_handler = apply_r_riscv_add64_rela,
				    .accumulate_handler = apply_64_bit_accumulation },
	[R_RISCV_SUB8]		= { .reloc_handler = apply_r_riscv_sub8_rela,
				    .accumulate_handler = apply_8_bit_accumulation },
	[R_RISCV_SUB16]		= { .reloc_handler = apply_r_riscv_sub16_rela,
				    .accumulate_handler = apply_16_bit_accumulation },
	[R_RISCV_SUB32]		= { .reloc_handler = apply_r_riscv_sub32_rela,
				    .accumulate_handler = apply_32_bit_accumulation },
	[R_RISCV_SUB64]		= { .reloc_handler = apply_r_riscv_sub64_rela,
				    .accumulate_handler = apply_64_bit_accumulation },
	/* 41-42 reserved for future standard use */
	[R_RISCV_ALIGN]		= { .reloc_handler = apply_r_riscv_align_rela },
	[R_RISCV_RVC_BRANCH]	= { .reloc_handler = apply_r_riscv_rvc_branch_rela },
	[R_RISCV_RVC_JUMP]	= { .reloc_handler = apply_r_riscv_rvc_jump_rela },
	/* 46-50 reserved for future standard use */
	[R_RISCV_RELAX]		= { .reloc_handler = apply_r_riscv_relax_rela },
	[R_RISCV_SUB6]		= { .reloc_handler = apply_r_riscv_sub6_rela,
				    .accumulate_handler = apply_6_bit_accumulation },
	[R_RISCV_SET6]		= { .reloc_handler = apply_r_riscv_set6_rela,
				    .accumulate_handler = apply_6_bit_accumulation },
	[R_RISCV_SET8]		= { .reloc_handler = apply_r_riscv_set8_rela,
				    .accumulate_handler = apply_8_bit_accumulation },
	[R_RISCV_SET16]		= { .reloc_handler = apply_r_riscv_set16_rela,
				    .accumulate_handler = apply_16_bit_accumulation },
	[R_RISCV_SET32]		= { .reloc_handler = apply_r_riscv_set32_rela,
				    .accumulate_handler = apply_32_bit_accumulation },
	[R_RISCV_32_PCREL]	= { .reloc_handler = apply_r_riscv_32_pcrel_rela },
	[R_RISCV_IRELATIVE]	= { .reloc_handler = dynamic_linking_not_supported },
	[R_RISCV_PLT32]		= { .reloc_handler = apply_r_riscv_plt32_rela },
	[R_RISCV_SET_ULEB128]	= { .reloc_handler = apply_r_riscv_set_uleb128,
				    .accumulate_handler = apply_uleb128_accumulation },
	[R_RISCV_SUB_ULEB128]	= { .reloc_handler = apply_r_riscv_sub_uleb128,
				    .accumulate_handler = apply_uleb128_accumulation },
	/* 62-191 reserved for future standard use */
	/* 192-255 nonstandard ABI extensions  */
};

static void
process_accumulated_relocations(struct module *me,
				struct hlist_head **relocation_hashtable,
				struct list_head *used_buckets_list)
{
	/*
	 * Only ADD/SUB/SET/ULEB128 should end up here.
	 *
	 * Each bucket may have more than one relocation location. All
	 * relocations for a location are stored in a list in a bucket.
	 *
	 * Relocations are applied to a temp variable before being stored to the
	 * provided location to check for overflow. This also allows ULEB128 to
	 * properly decide how many entries are needed before storing to
	 * location. The final value is stored into location using the handler
	 * for the last relocation to an address.
	 *
	 * Three layers of indexing:
	 *	- Each of the buckets in use
	 *	- Groups of relocations in each bucket by location address
	 *	- Each relocation entry for a location address
	 */
	struct used_bucket *bucket_iter;
	struct used_bucket *bucket_iter_tmp;
	struct relocation_head *rel_head_iter;
	struct hlist_node *rel_head_iter_tmp;
	struct relocation_entry *rel_entry_iter;
	struct relocation_entry *rel_entry_iter_tmp;
	int curr_type;
	void *location;
	long buffer;

	list_for_each_entry_safe(bucket_iter, bucket_iter_tmp,
				 used_buckets_list, head) {
		hlist_for_each_entry_safe(rel_head_iter, rel_head_iter_tmp,
					  bucket_iter->bucket, node) {
			buffer = 0;
			location = rel_head_iter->location;
			list_for_each_entry_safe(rel_entry_iter,
						 rel_entry_iter_tmp,
						 rel_head_iter->rel_entry,
						 head) {
				curr_type = rel_entry_iter->type;
				reloc_handlers[curr_type].reloc_handler(
					me, &buffer, rel_entry_iter->value);
				kfree(rel_entry_iter);
			}
			reloc_handlers[curr_type].accumulate_handler(
				me, location, buffer);
			kfree(rel_head_iter);
		}
		kfree(bucket_iter);
	}

	kfree(*relocation_hashtable);
}

static int add_relocation_to_accumulate(struct module *me, int type,
					void *location,
					unsigned int hashtable_bits, Elf_Addr v,
					struct hlist_head *relocation_hashtable,
					struct list_head *used_buckets_list)
{
	struct relocation_entry *entry;
	struct relocation_head *rel_head;
	struct hlist_head *current_head;
	struct used_bucket *bucket;
	unsigned long hash;

	entry = kmalloc(sizeof(*entry), GFP_KERNEL);

	if (!entry)
		return -ENOMEM;

	INIT_LIST_HEAD(&entry->head);
	entry->type = type;
	entry->value = v;

	hash = hash_min((uintptr_t)location, hashtable_bits);

	current_head = &relocation_hashtable[hash];

	/*
	 * Search for the relocation_head for the relocations that happen at the
	 * provided location
	 */
	bool found = false;
	struct relocation_head *rel_head_iter;

	hlist_for_each_entry(rel_head_iter, current_head, node) {
		if (rel_head_iter->location == location) {
			found = true;
			rel_head = rel_head_iter;
			break;
		}
	}

	/*
	 * If there has not yet been any relocations at the provided location,
	 * create a relocation_head for that location and populate it with this
	 * relocation_entry.
	 */
	if (!found) {
		rel_head = kmalloc(sizeof(*rel_head), GFP_KERNEL);

		if (!rel_head) {
			kfree(entry);
			return -ENOMEM;
		}

		rel_head->rel_entry =
			kmalloc(sizeof(struct list_head), GFP_KERNEL);

		if (!rel_head->rel_entry) {
			kfree(entry);
			kfree(rel_head);
			return -ENOMEM;
		}

		INIT_LIST_HEAD(rel_head->rel_entry);
		rel_head->location = location;
		INIT_HLIST_NODE(&rel_head->node);
		if (!current_head->first) {
			bucket =
				kmalloc(sizeof(struct used_bucket), GFP_KERNEL);

			if (!bucket) {
				kfree(entry);
				kfree(rel_head->rel_entry);
				kfree(rel_head);
				return -ENOMEM;
			}

			INIT_LIST_HEAD(&bucket->head);
			bucket->bucket = current_head;
			list_add(&bucket->head, used_buckets_list);
		}
		hlist_add_head(&rel_head->node, current_head);
	}

	/* Add relocation to head of discovered rel_head */
	list_add_tail(&entry->head, rel_head->rel_entry);

	return 0;
}

static unsigned int
initialize_relocation_hashtable(unsigned int num_relocations,
				struct hlist_head **relocation_hashtable)
{
	/* Can safely assume that bits is not greater than sizeof(long) */
	unsigned long hashtable_size = roundup_pow_of_two(num_relocations);
	/*
	 * When hashtable_size == 1, hashtable_bits == 0.
	 * This is valid because the hashing algorithm returns 0 in this case.
	 */
	unsigned int hashtable_bits = ilog2(hashtable_size);

	/*
	 * Double size of hashtable if num_relocations * 1.25 is greater than
	 * hashtable_size.
	 */
	int should_double_size = ((num_relocations + (num_relocations >> 2)) > (hashtable_size));

	hashtable_bits += should_double_size;

	hashtable_size <<= should_double_size;

	*relocation_hashtable = kmalloc_array(hashtable_size,
					      sizeof(**relocation_hashtable),
					      GFP_KERNEL);
	if (!*relocation_hashtable)
		return 0;

	__hash_init(*relocation_hashtable, hashtable_size);

	return hashtable_bits;
}

int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
		       unsigned int symindex, unsigned int relsec,
		       struct module *me)
{
	Elf_Rela *rel = (void *) sechdrs[relsec].sh_addr;
	int (*handler)(struct module *me, void *location, Elf_Addr v);
	Elf_Sym *sym;
	void *location;
	unsigned int i, type;
	unsigned int j_idx = 0;
	Elf_Addr v;
	int res;
	unsigned int num_relocations = sechdrs[relsec].sh_size / sizeof(*rel);
	struct hlist_head *relocation_hashtable;
	struct list_head used_buckets_list;
	unsigned int hashtable_bits;

	hashtable_bits = initialize_relocation_hashtable(num_relocations,
							 &relocation_hashtable);

	if (!relocation_hashtable)
		return -ENOMEM;

	INIT_LIST_HEAD(&used_buckets_list);

	pr_debug("Applying relocate section %u to %u\n", relsec,
	       sechdrs[relsec].sh_info);

	for (i = 0; i < num_relocations; i++) {
		/* This is where to make the change */
		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
			+ rel[i].r_offset;
		/* This is the symbol it is referring to */
		sym = (Elf_Sym *)sechdrs[symindex].sh_addr
			+ ELF_RISCV_R_SYM(rel[i].r_info);
		if (IS_ERR_VALUE(sym->st_value)) {
			/* Ignore unresolved weak symbol */
			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
				continue;
			pr_warn("%s: Unknown symbol %s\n",
				me->name, strtab + sym->st_name);
			return -ENOENT;
		}

		type = ELF_RISCV_R_TYPE(rel[i].r_info);

		if (type < ARRAY_SIZE(reloc_handlers))
			handler = reloc_handlers[type].reloc_handler;
		else
			handler = NULL;

		if (!handler) {
			pr_err("%s: Unknown relocation type %u\n",
			       me->name, type);
			return -EINVAL;
		}

		v = sym->st_value + rel[i].r_addend;

		if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) {
			unsigned int j = j_idx;
			bool found = false;

			do {
				unsigned long hi20_loc =
					sechdrs[sechdrs[relsec].sh_info].sh_addr
					+ rel[j].r_offset;
				u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info);

				/* Find the corresponding HI20 relocation entry */
				if (hi20_loc == sym->st_value
				    && (hi20_type == R_RISCV_PCREL_HI20
					|| hi20_type == R_RISCV_GOT_HI20)) {
					s32 hi20, lo12;
					Elf_Sym *hi20_sym =
						(Elf_Sym *)sechdrs[symindex].sh_addr
						+ ELF_RISCV_R_SYM(rel[j].r_info);
					unsigned long hi20_sym_val =
						hi20_sym->st_value
						+ rel[j].r_addend;

					/* Calculate lo12 */
					size_t offset = hi20_sym_val - hi20_loc;
					if (IS_ENABLED(CONFIG_MODULE_SECTIONS)
					    && hi20_type == R_RISCV_GOT_HI20) {
						offset = module_emit_got_entry(
							 me, hi20_sym_val);
						offset = offset - hi20_loc;
					}
					hi20 = (offset + 0x800) & 0xfffff000;
					lo12 = offset - hi20;
					v = lo12;
					found = true;

					break;
				}

				j++;
				if (j > sechdrs[relsec].sh_size / sizeof(*rel))
					j = 0;

			} while (j_idx != j);

			if (!found) {
				pr_err(
				  "%s: Can not find HI20 relocation information\n",
				  me->name);
				return -EINVAL;
			}

			/* Record the previous j-loop end index */
			j_idx = j;
		}

		if (reloc_handlers[type].accumulate_handler)
			res = add_relocation_to_accumulate(me, type, location,
							   hashtable_bits, v,
							   relocation_hashtable,
							   &used_buckets_list);
		else
			res = handler(me, location, v);
		if (res)
			return res;
	}

	process_accumulated_relocations(me, &relocation_hashtable,
					&used_buckets_list);

	return 0;
}

#if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
void *module_alloc(unsigned long size)
{
	return __vmalloc_node_range(size, 1, MODULES_VADDR,
				    MODULES_END, GFP_KERNEL,
				    PAGE_KERNEL, VM_FLUSH_RESET_PERMS,
				    NUMA_NO_NODE,
				    __builtin_return_address(0));
}
#endif

int module_finalize(const Elf_Ehdr *hdr,
		    const Elf_Shdr *sechdrs,
		    struct module *me)
{
	const Elf_Shdr *s;

	s = find_section(hdr, sechdrs, ".alternative");
	if (s)
		apply_module_alternatives((void *)s->sh_addr, s->sh_size);

	return 0;
}