aboutsummaryrefslogtreecommitdiff
path: root/arch/arc/mm/tlb.c
blob: fa18c00b0cfd7de6afc7985ff5a67161608f89b0 (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
/*
 * TLB Management (flush/create/diagnostics) for ARC700
 *
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.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 as
 * published by the Free Software Foundation.
 *
 * vineetg: Aug 2011
 *  -Reintroduce duplicate PD fixup - some customer chips still have the issue
 *
 * vineetg: May 2011
 *  -No need to flush_cache_page( ) for each call to update_mmu_cache()
 *   some of the LMBench tests improved amazingly
 *      = page-fault thrice as fast (75 usec to 28 usec)
 *      = mmap twice as fast (9.6 msec to 4.6 msec),
 *      = fork (5.3 msec to 3.7 msec)
 *
 * vineetg: April 2011 :
 *  -MMU v3: PD{0,1} bits layout changed: They don't overlap anymore,
 *      helps avoid a shift when preparing PD0 from PTE
 *
 * vineetg: April 2011 : Preparing for MMU V3
 *  -MMU v2/v3 BCRs decoded differently
 *  -Remove TLB_SIZE hardcoding as it's variable now: 256 or 512
 *  -tlb_entry_erase( ) can be void
 *  -local_flush_tlb_range( ):
 *      = need not "ceil" @end
 *      = walks MMU only if range spans < 32 entries, as opposed to 256
 *
 * Vineetg: Sept 10th 2008
 *  -Changes related to MMU v2 (Rel 4.8)
 *
 * Vineetg: Aug 29th 2008
 *  -In TLB Flush operations (Metal Fix MMU) there is a explict command to
 *    flush Micro-TLBS. If TLB Index Reg is invalid prior to TLBIVUTLB cmd,
 *    it fails. Thus need to load it with ANY valid value before invoking
 *    TLBIVUTLB cmd
 *
 * Vineetg: Aug 21th 2008:
 *  -Reduced the duration of IRQ lockouts in TLB Flush routines
 *  -Multiple copies of TLB erase code seperated into a "single" function
 *  -In TLB Flush routines, interrupt disabling moved UP to retrieve ASID
 *       in interrupt-safe region.
 *
 * Vineetg: April 23rd Bug #93131
 *    Problem: tlb_flush_kernel_range() doesn't do anything if the range to
 *              flush is more than the size of TLB itself.
 *
 * Rahul Trivedi : Codito Technologies 2004
 */

#include <linux/module.h>
#include <linux/bug.h>
#include <linux/mm_types.h>

#include <asm/arcregs.h>
#include <asm/setup.h>
#include <asm/mmu_context.h>
#include <asm/mmu.h>

/*			Need for ARC MMU v2
 *
 * ARC700 MMU-v1 had a Joint-TLB for Code and Data and is 2 way set-assoc.
 * For a memcpy operation with 3 players (src/dst/code) such that all 3 pages
 * map into same set, there would be contention for the 2 ways causing severe
 * Thrashing.
 *
 * Although J-TLB is 2 way set assoc, ARC700 caches J-TLB into uTLBS which has
 * much higher associativity. u-D-TLB is 8 ways, u-I-TLB is 4 ways.
 * Given this, the thrasing problem should never happen because once the 3
 * J-TLB entries are created (even though 3rd will knock out one of the prev
 * two), the u-D-TLB and u-I-TLB will have what is required to accomplish memcpy
 *
 * Yet we still see the Thrashing because a J-TLB Write cause flush of u-TLBs.
 * This is a simple design for keeping them in sync. So what do we do?
 * The solution which James came up was pretty neat. It utilised the assoc
 * of uTLBs by not invalidating always but only when absolutely necessary.
 *
 * - Existing TLB commands work as before
 * - New command (TLBWriteNI) for TLB write without clearing uTLBs
 * - New command (TLBIVUTLB) to invalidate uTLBs.
 *
 * The uTLBs need only be invalidated when pages are being removed from the
 * OS page table. If a 'victim' TLB entry is being overwritten in the main TLB
 * as a result of a miss, the removed entry is still allowed to exist in the
 * uTLBs as it is still valid and present in the OS page table. This allows the
 * full associativity of the uTLBs to hide the limited associativity of the main
 * TLB.
 *
 * During a miss handler, the new "TLBWriteNI" command is used to load
 * entries without clearing the uTLBs.
 *
 * When the OS page table is updated, TLB entries that may be associated with a
 * removed page are removed (flushed) from the TLB using TLBWrite. In this
 * circumstance, the uTLBs must also be cleared. This is done by using the
 * existing TLBWrite command. An explicit IVUTLB is also required for those
 * corner cases when TLBWrite was not executed at all because the corresp
 * J-TLB entry got evicted/replaced.
 */


/* A copy of the ASID from the PID reg is kept in asid_cache */
DEFINE_PER_CPU(unsigned int, asid_cache) = MM_CTXT_FIRST_CYCLE;

static int __read_mostly pae_exists;

/*
 * Utility Routine to erase a J-TLB entry
 * Caller needs to setup Index Reg (manually or via getIndex)
 */
static inline void __tlb_entry_erase(void)
{
	write_aux_reg(ARC_REG_TLBPD1, 0);

	if (is_pae40_enabled())
		write_aux_reg(ARC_REG_TLBPD1HI, 0);

	write_aux_reg(ARC_REG_TLBPD0, 0);
	write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
}

#if (CONFIG_ARC_MMU_VER < 4)

static inline unsigned int tlb_entry_lkup(unsigned long vaddr_n_asid)
{
	unsigned int idx;

	write_aux_reg(ARC_REG_TLBPD0, vaddr_n_asid);

	write_aux_reg(ARC_REG_TLBCOMMAND, TLBProbe);
	idx = read_aux_reg(ARC_REG_TLBINDEX);

	return idx;
}

static void tlb_entry_erase(unsigned int vaddr_n_asid)
{
	unsigned int idx;

	/* Locate the TLB entry for this vaddr + ASID */
	idx = tlb_entry_lkup(vaddr_n_asid);

	/* No error means entry found, zero it out */
	if (likely(!(idx & TLB_LKUP_ERR))) {
		__tlb_entry_erase();
	} else {
		/* Duplicate entry error */
		WARN(idx == TLB_DUP_ERR, "Probe returned Dup PD for %x\n",
					   vaddr_n_asid);
	}
}

/****************************************************************************
 * ARC700 MMU caches recently used J-TLB entries (RAM) as uTLBs (FLOPs)
 *
 * New IVUTLB cmd in MMU v2 explictly invalidates the uTLB
 *
 * utlb_invalidate ( )
 *  -For v2 MMU calls Flush uTLB Cmd
 *  -For v1 MMU does nothing (except for Metal Fix v1 MMU)
 *      This is because in v1 TLBWrite itself invalidate uTLBs
 ***************************************************************************/

static void utlb_invalidate(void)
{
#if (CONFIG_ARC_MMU_VER >= 2)

#if (CONFIG_ARC_MMU_VER == 2)
	/* MMU v2 introduced the uTLB Flush command.
	 * There was however an obscure hardware bug, where uTLB flush would
	 * fail when a prior probe for J-TLB (both totally unrelated) would
	 * return lkup err - because the entry didn't exist in MMU.
	 * The Workround was to set Index reg with some valid value, prior to
	 * flush. This was fixed in MMU v3 hence not needed any more
	 */
	unsigned int idx;

	/* make sure INDEX Reg is valid */
	idx = read_aux_reg(ARC_REG_TLBINDEX);

	/* If not write some dummy val */
	if (unlikely(idx & TLB_LKUP_ERR))
		write_aux_reg(ARC_REG_TLBINDEX, 0xa);
#endif

	write_aux_reg(ARC_REG_TLBCOMMAND, TLBIVUTLB);
#endif

}

static void tlb_entry_insert(unsigned int pd0, pte_t pd1)
{
	unsigned int idx;

	/*
	 * First verify if entry for this vaddr+ASID already exists
	 * This also sets up PD0 (vaddr, ASID..) for final commit
	 */
	idx = tlb_entry_lkup(pd0);

	/*
	 * If Not already present get a free slot from MMU.
	 * Otherwise, Probe would have located the entry and set INDEX Reg
	 * with existing location. This will cause Write CMD to over-write
	 * existing entry with new PD0 and PD1
	 */
	if (likely(idx & TLB_LKUP_ERR))
		write_aux_reg(ARC_REG_TLBCOMMAND, TLBGetIndex);

	/* setup the other half of TLB entry (pfn, rwx..) */
	write_aux_reg(ARC_REG_TLBPD1, pd1);

	/*
	 * Commit the Entry to MMU
	 * It doesn't sound safe to use the TLBWriteNI cmd here
	 * which doesn't flush uTLBs. I'd rather be safe than sorry.
	 */
	write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
}

#else	/* CONFIG_ARC_MMU_VER >= 4) */

static void utlb_invalidate(void)
{
	/* No need since uTLB is always in sync with JTLB */
}

static void tlb_entry_erase(unsigned int vaddr_n_asid)
{
	write_aux_reg(ARC_REG_TLBPD0, vaddr_n_asid | _PAGE_PRESENT);
	write_aux_reg(ARC_REG_TLBCOMMAND, TLBDeleteEntry);
}

static void tlb_entry_insert(unsigned int pd0, pte_t pd1)
{
	write_aux_reg(ARC_REG_TLBPD0, pd0);
	write_aux_reg(ARC_REG_TLBPD1, pd1);

	if (is_pae40_enabled())
		write_aux_reg(ARC_REG_TLBPD1HI, (u64)pd1 >> 32);

	write_aux_reg(ARC_REG_TLBCOMMAND, TLBInsertEntry);
}

#endif

/*
 * Un-conditionally (without lookup) erase the entire MMU contents
 */

noinline void local_flush_tlb_all(void)
{
	struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
	unsigned long flags;
	unsigned int entry;
	int num_tlb = mmu->sets * mmu->ways;

	local_irq_save(flags);

	/* Load PD0 and PD1 with template for a Blank Entry */
	write_aux_reg(ARC_REG_TLBPD1, 0);

	if (is_pae40_enabled())
		write_aux_reg(ARC_REG_TLBPD1HI, 0);

	write_aux_reg(ARC_REG_TLBPD0, 0);

	for (entry = 0; entry < num_tlb; entry++) {
		/* write this entry to the TLB */
		write_aux_reg(ARC_REG_TLBINDEX, entry);
		write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
	}

	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
		const int stlb_idx = 0x800;

		/* Blank sTLB entry */
		write_aux_reg(ARC_REG_TLBPD0, _PAGE_HW_SZ);

		for (entry = stlb_idx; entry < stlb_idx + 16; entry++) {
			write_aux_reg(ARC_REG_TLBINDEX, entry);
			write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
		}
	}

	utlb_invalidate();

	local_irq_restore(flags);
}

/*
 * Flush the entrie MM for userland. The fastest way is to move to Next ASID
 */
noinline void local_flush_tlb_mm(struct mm_struct *mm)
{
	/*
	 * Small optimisation courtesy IA64
	 * flush_mm called during fork,exit,munmap etc, multiple times as well.
	 * Only for fork( ) do we need to move parent to a new MMU ctxt,
	 * all other cases are NOPs, hence this check.
	 */
	if (atomic_read(&mm->mm_users) == 0)
		return;

	/*
	 * - Move to a new ASID, but only if the mm is still wired in
	 *   (Android Binder ended up calling this for vma->mm != tsk->mm,
	 *    causing h/w - s/w ASID to get out of sync)
	 * - Also get_new_mmu_context() new implementation allocates a new
	 *   ASID only if it is not allocated already - so unallocate first
	 */
	destroy_context(mm);
	if (current->mm == mm)
		get_new_mmu_context(mm);
}

/*
 * Flush a Range of TLB entries for userland.
 * @start is inclusive, while @end is exclusive
 * Difference between this and Kernel Range Flush is
 *  -Here the fastest way (if range is too large) is to move to next ASID
 *      without doing any explicit Shootdown
 *  -In case of kernel Flush, entry has to be shot down explictly
 */
void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
			   unsigned long end)
{
	const unsigned int cpu = smp_processor_id();
	unsigned long flags;

	/* If range @start to @end is more than 32 TLB entries deep,
	 * its better to move to a new ASID rather than searching for
	 * individual entries and then shooting them down
	 *
	 * The calc above is rough, doesn't account for unaligned parts,
	 * since this is heuristics based anyways
	 */
	if (unlikely((end - start) >= PAGE_SIZE * 32)) {
		local_flush_tlb_mm(vma->vm_mm);
		return;
	}

	/*
	 * @start moved to page start: this alone suffices for checking
	 * loop end condition below, w/o need for aligning @end to end
	 * e.g. 2000 to 4001 will anyhow loop twice
	 */
	start &= PAGE_MASK;

	local_irq_save(flags);

	if (asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID) {
		while (start < end) {
			tlb_entry_erase(start | hw_pid(vma->vm_mm, cpu));
			start += PAGE_SIZE;
		}
	}

	utlb_invalidate();

	local_irq_restore(flags);
}

/* Flush the kernel TLB entries - vmalloc/modules (Global from MMU perspective)
 *  @start, @end interpreted as kvaddr
 * Interestingly, shared TLB entries can also be flushed using just
 * @start,@end alone (interpreted as user vaddr), although technically SASID
 * is also needed. However our smart TLbProbe lookup takes care of that.
 */
void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
	unsigned long flags;

	/* exactly same as above, except for TLB entry not taking ASID */

	if (unlikely((end - start) >= PAGE_SIZE * 32)) {
		local_flush_tlb_all();
		return;
	}

	start &= PAGE_MASK;

	local_irq_save(flags);
	while (start < end) {
		tlb_entry_erase(start);
		start += PAGE_SIZE;
	}

	utlb_invalidate();

	local_irq_restore(flags);
}

/*
 * Delete TLB entry in MMU for a given page (??? address)
 * NOTE One TLB entry contains translation for single PAGE
 */

void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
	const unsigned int cpu = smp_processor_id();
	unsigned long flags;

	/* Note that it is critical that interrupts are DISABLED between
	 * checking the ASID and using it flush the TLB entry
	 */
	local_irq_save(flags);

	if (asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID) {
		tlb_entry_erase((page & PAGE_MASK) | hw_pid(vma->vm_mm, cpu));
		utlb_invalidate();
	}

	local_irq_restore(flags);
}

#ifdef CONFIG_SMP

struct tlb_args {
	struct vm_area_struct *ta_vma;
	unsigned long ta_start;
	unsigned long ta_end;
};

static inline void ipi_flush_tlb_page(void *arg)
{
	struct tlb_args *ta = arg;

	local_flush_tlb_page(ta->ta_vma, ta->ta_start);
}

static inline void ipi_flush_tlb_range(void *arg)
{
	struct tlb_args *ta = arg;

	local_flush_tlb_range(ta->ta_vma, ta->ta_start, ta->ta_end);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline void ipi_flush_pmd_tlb_range(void *arg)
{
	struct tlb_args *ta = arg;

	local_flush_pmd_tlb_range(ta->ta_vma, ta->ta_start, ta->ta_end);
}
#endif

static inline void ipi_flush_tlb_kernel_range(void *arg)
{
	struct tlb_args *ta = (struct tlb_args *)arg;

	local_flush_tlb_kernel_range(ta->ta_start, ta->ta_end);
}

void flush_tlb_all(void)
{
	on_each_cpu((smp_call_func_t)local_flush_tlb_all, NULL, 1);
}

void flush_tlb_mm(struct mm_struct *mm)
{
	on_each_cpu_mask(mm_cpumask(mm), (smp_call_func_t)local_flush_tlb_mm,
			 mm, 1);
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
{
	struct tlb_args ta = {
		.ta_vma = vma,
		.ta_start = uaddr
	};

	on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_tlb_page, &ta, 1);
}

void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
		     unsigned long end)
{
	struct tlb_args ta = {
		.ta_vma = vma,
		.ta_start = start,
		.ta_end = end
	};

	on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_tlb_range, &ta, 1);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
			 unsigned long end)
{
	struct tlb_args ta = {
		.ta_vma = vma,
		.ta_start = start,
		.ta_end = end
	};

	on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_pmd_tlb_range, &ta, 1);
}
#endif

void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
	struct tlb_args ta = {
		.ta_start = start,
		.ta_end = end
	};

	on_each_cpu(ipi_flush_tlb_kernel_range, &ta, 1);
}
#endif

/*
 * Routine to create a TLB entry
 */
void create_tlb(struct vm_area_struct *vma, unsigned long vaddr, pte_t *ptep)
{
	unsigned long flags;
	unsigned int asid_or_sasid, rwx;
	unsigned long pd0;
	pte_t pd1;

	/*
	 * create_tlb() assumes that current->mm == vma->mm, since
	 * -it ASID for TLB entry is fetched from MMU ASID reg (valid for curr)
	 * -completes the lazy write to SASID reg (again valid for curr tsk)
	 *
	 * Removing the assumption involves
	 * -Using vma->mm->context{ASID,SASID}, as opposed to MMU reg.
	 * -Fix the TLB paranoid debug code to not trigger false negatives.
	 * -More importantly it makes this handler inconsistent with fast-path
	 *  TLB Refill handler which always deals with "current"
	 *
	 * Lets see the use cases when current->mm != vma->mm and we land here
	 *  1. execve->copy_strings()->__get_user_pages->handle_mm_fault
	 *     Here VM wants to pre-install a TLB entry for user stack while
	 *     current->mm still points to pre-execve mm (hence the condition).
	 *     However the stack vaddr is soon relocated (randomization) and
	 *     move_page_tables() tries to undo that TLB entry.
	 *     Thus not creating TLB entry is not any worse.
	 *
	 *  2. ptrace(POKETEXT) causes a CoW - debugger(current) inserting a
	 *     breakpoint in debugged task. Not creating a TLB now is not
	 *     performance critical.
	 *
	 * Both the cases above are not good enough for code churn.
	 */
	if (current->active_mm != vma->vm_mm)
		return;

	local_irq_save(flags);

	tlb_paranoid_check(asid_mm(vma->vm_mm, smp_processor_id()), vaddr);

	vaddr &= PAGE_MASK;

	/* update this PTE credentials */
	pte_val(*ptep) |= (_PAGE_PRESENT | _PAGE_ACCESSED);

	/* Create HW TLB(PD0,PD1) from PTE  */

	/* ASID for this task */
	asid_or_sasid = read_aux_reg(ARC_REG_PID) & 0xff;

	pd0 = vaddr | asid_or_sasid | (pte_val(*ptep) & PTE_BITS_IN_PD0);

	/*
	 * ARC MMU provides fully orthogonal access bits for K/U mode,
	 * however Linux only saves 1 set to save PTE real-estate
	 * Here we convert 3 PTE bits into 6 MMU bits:
	 * -Kernel only entries have Kr Kw Kx 0 0 0
	 * -User entries have mirrored K and U bits
	 */
	rwx = pte_val(*ptep) & PTE_BITS_RWX;

	if (pte_val(*ptep) & _PAGE_GLOBAL)
		rwx <<= 3;		/* r w x => Kr Kw Kx 0 0 0 */
	else
		rwx |= (rwx << 3);	/* r w x => Kr Kw Kx Ur Uw Ux */

	pd1 = rwx | (pte_val(*ptep) & PTE_BITS_NON_RWX_IN_PD1);

	tlb_entry_insert(pd0, pd1);

	local_irq_restore(flags);
}

/*
 * Called at the end of pagefault, for a userspace mapped page
 *  -pre-install the corresponding TLB entry into MMU
 *  -Finalize the delayed D-cache flush of kernel mapping of page due to
 *  	flush_dcache_page(), copy_user_page()
 *
 * Note that flush (when done) involves both WBACK - so physical page is
 * in sync as well as INV - so any non-congruent aliases don't remain
 */
void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddr_unaligned,
		      pte_t *ptep)
{
	unsigned long vaddr = vaddr_unaligned & PAGE_MASK;
	phys_addr_t paddr = pte_val(*ptep) & PAGE_MASK;
	struct page *page = pfn_to_page(pte_pfn(*ptep));

	create_tlb(vma, vaddr, ptep);

	if (page == ZERO_PAGE(0)) {
		return;
	}

	/*
	 * Exec page : Independent of aliasing/page-color considerations,
	 *	       since icache doesn't snoop dcache on ARC, any dirty
	 *	       K-mapping of a code page needs to be wback+inv so that
	 *	       icache fetch by userspace sees code correctly.
	 * !EXEC page: If K-mapping is NOT congruent to U-mapping, flush it
	 *	       so userspace sees the right data.
	 *  (Avoids the flush for Non-exec + congruent mapping case)
	 */
	if ((vma->vm_flags & VM_EXEC) ||
	     addr_not_cache_congruent(paddr, vaddr)) {

		int dirty = !test_and_set_bit(PG_dc_clean, &page->flags);
		if (dirty) {
			/* wback + inv dcache lines (K-mapping) */
			__flush_dcache_page(paddr, paddr);

			/* invalidate any existing icache lines (U-mapping) */
			if (vma->vm_flags & VM_EXEC)
				__inv_icache_page(paddr, vaddr);
		}
	}
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

/*
 * MMUv4 in HS38x cores supports Super Pages which are basis for Linux THP
 * support.
 *
 * Normal and Super pages can co-exist (ofcourse not overlap) in TLB with a
 * new bit "SZ" in TLB page descriptor to distinguish between them.
 * Super Page size is configurable in hardware (4K to 16M), but fixed once
 * RTL builds.
 *
 * The exact THP size a Linx configuration will support is a function of:
 *  - MMU page size (typical 8K, RTL fixed)
 *  - software page walker address split between PGD:PTE:PFN (typical
 *    11:8:13, but can be changed with 1 line)
 * So for above default, THP size supported is 8K * (2^8) = 2M
 *
 * Default Page Walker is 2 levels, PGD:PTE:PFN, which in THP regime
 * reduces to 1 level (as PTE is folded into PGD and canonically referred
 * to as PMD).
 * Thus THP PMD accessors are implemented in terms of PTE (just like sparc)
 */

void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
				 pmd_t *pmd)
{
	pte_t pte = __pte(pmd_val(*pmd));
	update_mmu_cache(vma, addr, &pte);
}

void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
				pgtable_t pgtable)
{
	struct list_head *lh = (struct list_head *) pgtable;

	assert_spin_locked(&mm->page_table_lock);

	/* FIFO */
	if (!pmd_huge_pte(mm, pmdp))
		INIT_LIST_HEAD(lh);
	else
		list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
	pmd_huge_pte(mm, pmdp) = pgtable;
}

pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
{
	struct list_head *lh;
	pgtable_t pgtable;

	assert_spin_locked(&mm->page_table_lock);

	pgtable = pmd_huge_pte(mm, pmdp);
	lh = (struct list_head *) pgtable;
	if (list_empty(lh))
		pmd_huge_pte(mm, pmdp) = NULL;
	else {
		pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
		list_del(lh);
	}

	pte_val(pgtable[0]) = 0;
	pte_val(pgtable[1]) = 0;

	return pgtable;
}

void local_flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
			       unsigned long end)
{
	unsigned int cpu;
	unsigned long flags;

	local_irq_save(flags);

	cpu = smp_processor_id();

	if (likely(asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID)) {
		unsigned int asid = hw_pid(vma->vm_mm, cpu);

		/* No need to loop here: this will always be for 1 Huge Page */
		tlb_entry_erase(start | _PAGE_HW_SZ | asid);
	}

	local_irq_restore(flags);
}

#endif

/* Read the Cache Build Confuration Registers, Decode them and save into
 * the cpuinfo structure for later use.
 * No Validation is done here, simply read/convert the BCRs
 */
void read_decode_mmu_bcr(void)
{
	struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
	unsigned int tmp;
	struct bcr_mmu_1_2 {
#ifdef CONFIG_CPU_BIG_ENDIAN
		unsigned int ver:8, ways:4, sets:4, u_itlb:8, u_dtlb:8;
#else
		unsigned int u_dtlb:8, u_itlb:8, sets:4, ways:4, ver:8;
#endif
	} *mmu2;

	struct bcr_mmu_3 {
#ifdef CONFIG_CPU_BIG_ENDIAN
	unsigned int ver:8, ways:4, sets:4, res:3, sasid:1, pg_sz:4,
		     u_itlb:4, u_dtlb:4;
#else
	unsigned int u_dtlb:4, u_itlb:4, pg_sz:4, sasid:1, res:3, sets:4,
		     ways:4, ver:8;
#endif
	} *mmu3;

	struct bcr_mmu_4 {
#ifdef CONFIG_CPU_BIG_ENDIAN
	unsigned int ver:8, sasid:1, sz1:4, sz0:4, res:2, pae:1,
		     n_ways:2, n_entry:2, n_super:2, u_itlb:3, u_dtlb:3;
#else
	/*           DTLB      ITLB      JES        JE         JA      */
	unsigned int u_dtlb:3, u_itlb:3, n_super:2, n_entry:2, n_ways:2,
		     pae:1, res:2, sz0:4, sz1:4, sasid:1, ver:8;
#endif
	} *mmu4;

	tmp = read_aux_reg(ARC_REG_MMU_BCR);
	mmu->ver = (tmp >> 24);

	if (is_isa_arcompact()) {
		if (mmu->ver <= 2) {
			mmu2 = (struct bcr_mmu_1_2 *)&tmp;
			mmu->pg_sz_k = TO_KB(0x2000);
			mmu->sets = 1 << mmu2->sets;
			mmu->ways = 1 << mmu2->ways;
			mmu->u_dtlb = mmu2->u_dtlb;
			mmu->u_itlb = mmu2->u_itlb;
		} else {
			mmu3 = (struct bcr_mmu_3 *)&tmp;
			mmu->pg_sz_k = 1 << (mmu3->pg_sz - 1);
			mmu->sets = 1 << mmu3->sets;
			mmu->ways = 1 << mmu3->ways;
			mmu->u_dtlb = mmu3->u_dtlb;
			mmu->u_itlb = mmu3->u_itlb;
			mmu->sasid = mmu3->sasid;
		}
	} else {
		mmu4 = (struct bcr_mmu_4 *)&tmp;
		mmu->pg_sz_k = 1 << (mmu4->sz0 - 1);
		mmu->s_pg_sz_m = 1 << (mmu4->sz1 - 11);
		mmu->sets = 64 << mmu4->n_entry;
		mmu->ways = mmu4->n_ways * 2;
		mmu->u_dtlb = mmu4->u_dtlb * 4;
		mmu->u_itlb = mmu4->u_itlb * 4;
		mmu->sasid = mmu4->sasid;
		pae_exists = mmu->pae = mmu4->pae;
	}
}

char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len)
{
	int n = 0;
	struct cpuinfo_arc_mmu *p_mmu = &cpuinfo_arc700[cpu_id].mmu;
	char super_pg[64] = "";

	if (p_mmu->s_pg_sz_m)
		scnprintf(super_pg, 64, "%dM Super Page %s",
			  p_mmu->s_pg_sz_m,
			  IS_USED_CFG(CONFIG_TRANSPARENT_HUGEPAGE));

	n += scnprintf(buf + n, len - n,
		      "MMU [v%x]\t: %dk PAGE, %sJTLB %d (%dx%d), uDTLB %d, uITLB %d%s%s\n",
		       p_mmu->ver, p_mmu->pg_sz_k, super_pg,
		       p_mmu->sets * p_mmu->ways, p_mmu->sets, p_mmu->ways,
		       p_mmu->u_dtlb, p_mmu->u_itlb,
		       IS_AVAIL2(p_mmu->pae, ", PAE40 ", CONFIG_ARC_HAS_PAE40));

	return buf;
}

int pae40_exist_but_not_enab(void)
{
	return pae_exists && !is_pae40_enabled();
}

void arc_mmu_init(void)
{
	struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
	char str[256];
	int compat = 0;

	pr_info("%s", arc_mmu_mumbojumbo(0, str, sizeof(str)));

	/*
	 * Can't be done in processor.h due to header include depenedencies
	 */
	BUILD_BUG_ON(!IS_ALIGNED((CONFIG_ARC_KVADDR_SIZE << 20), PMD_SIZE));

	/*
	 * stack top size sanity check,
	 * Can't be done in processor.h due to header include depenedencies
	 */
	BUILD_BUG_ON(!IS_ALIGNED(STACK_TOP, PMD_SIZE));

	/*
	 * Ensure that MMU features assumed by kernel exist in hardware.
	 * For older ARC700 cpus, it has to be exact match, since the MMU
	 * revisions were not backwards compatible (MMUv3 TLB layout changed
	 * so even if kernel for v2 didn't use any new cmds of v3, it would
	 * still not work.
	 * For HS cpus, MMUv4 was baseline and v5 is backwards compatible
	 * (will run older software).
	 */
	if (is_isa_arcompact() && mmu->ver == CONFIG_ARC_MMU_VER)
		compat = 1;
	else if (is_isa_arcv2() && mmu->ver >= CONFIG_ARC_MMU_VER)
		compat = 1;

	if (!compat) {
		panic("MMU ver %d doesn't match kernel built for %d...\n",
		      mmu->ver, CONFIG_ARC_MMU_VER);
	}

	if (mmu->pg_sz_k != TO_KB(PAGE_SIZE))
		panic("MMU pg size != PAGE_SIZE (%luk)\n", TO_KB(PAGE_SIZE));

	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
	    mmu->s_pg_sz_m != TO_MB(HPAGE_PMD_SIZE))
		panic("MMU Super pg size != Linux HPAGE_PMD_SIZE (%luM)\n",
		      (unsigned long)TO_MB(HPAGE_PMD_SIZE));

	if (IS_ENABLED(CONFIG_ARC_HAS_PAE40) && !mmu->pae)
		panic("Hardware doesn't support PAE40\n");

	/* Enable the MMU */
	write_aux_reg(ARC_REG_PID, MMU_ENABLE);

	/* In smp we use this reg for interrupt 1 scratch */
#ifndef CONFIG_SMP
	/* swapper_pg_dir is the pgd for the kernel, used by vmalloc */
	write_aux_reg(ARC_REG_SCRATCH_DATA0, swapper_pg_dir);
#endif

	if (pae40_exist_but_not_enab())
		write_aux_reg(ARC_REG_TLBPD1HI, 0);
}

/*
 * TLB Programmer's Model uses Linear Indexes: 0 to {255, 511} for 128 x {2,4}
 * The mapping is Column-first.
 *		---------------------	-----------
 *		|way0|way1|way2|way3|	|way0|way1|
 *		---------------------	-----------
 * [set0]	|  0 |  1 |  2 |  3 |	|  0 |  1 |
 * [set1]	|  4 |  5 |  6 |  7 |	|  2 |  3 |
 *		~		    ~	~	  ~
 * [set127]	| 508| 509| 510| 511|	| 254| 255|
 *		---------------------	-----------
 * For normal operations we don't(must not) care how above works since
 * MMU cmd getIndex(vaddr) abstracts that out.
 * However for walking WAYS of a SET, we need to know this
 */
#define SET_WAY_TO_IDX(mmu, set, way)  ((set) * mmu->ways + (way))

/* Handling of Duplicate PD (TLB entry) in MMU.
 * -Could be due to buggy customer tapeouts or obscure kernel bugs
 * -MMU complaints not at the time of duplicate PD installation, but at the
 *      time of lookup matching multiple ways.
 * -Ideally these should never happen - but if they do - workaround by deleting
 *      the duplicate one.
 * -Knob to be verbose abt it.(TODO: hook them up to debugfs)
 */
volatile int dup_pd_silent; /* Be slient abt it or complain (default) */

void do_tlb_overlap_fault(unsigned long cause, unsigned long address,
			  struct pt_regs *regs)
{
	struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
	unsigned long flags;
	int set, n_ways = mmu->ways;

	n_ways = min(n_ways, 4);
	BUG_ON(mmu->ways > 4);

	local_irq_save(flags);

	/* loop thru all sets of TLB */
	for (set = 0; set < mmu->sets; set++) {

		int is_valid, way;
		unsigned int pd0[4];

		/* read out all the ways of current set */
		for (way = 0, is_valid = 0; way < n_ways; way++) {
			write_aux_reg(ARC_REG_TLBINDEX,
					  SET_WAY_TO_IDX(mmu, set, way));
			write_aux_reg(ARC_REG_TLBCOMMAND, TLBRead);
			pd0[way] = read_aux_reg(ARC_REG_TLBPD0);
			is_valid |= pd0[way] & _PAGE_PRESENT;
			pd0[way] &= PAGE_MASK;
		}

		/* If all the WAYS in SET are empty, skip to next SET */
		if (!is_valid)
			continue;

		/* Scan the set for duplicate ways: needs a nested loop */
		for (way = 0; way < n_ways - 1; way++) {

			int n;

			if (!pd0[way])
				continue;

			for (n = way + 1; n < n_ways; n++) {
				if (pd0[way] != pd0[n])
					continue;

				if (!dup_pd_silent)
					pr_info("Dup TLB PD0 %08x @ set %d ways %d,%d\n",
						pd0[way], set, way, n);

				/*
				 * clear entry @way and not @n.
				 * This is critical to our optimised loop
				 */
				pd0[way] = 0;
				write_aux_reg(ARC_REG_TLBINDEX,
						SET_WAY_TO_IDX(mmu, set, way));
				__tlb_entry_erase();
			}
		}
	}

	local_irq_restore(flags);
}

/***********************************************************************
 * Diagnostic Routines
 *  -Called from Low Level TLB Hanlders if things don;t look good
 **********************************************************************/

#ifdef CONFIG_ARC_DBG_TLB_PARANOIA

/*
 * Low Level ASM TLB handler calls this if it finds that HW and SW ASIDS
 * don't match
 */
void print_asid_mismatch(int mm_asid, int mmu_asid, int is_fast_path)
{
	pr_emerg("ASID Mismatch in %s Path Handler: sw-pid=0x%x hw-pid=0x%x\n",
	       is_fast_path ? "Fast" : "Slow", mm_asid, mmu_asid);

	__asm__ __volatile__("flag 1");
}

void tlb_paranoid_check(unsigned int mm_asid, unsigned long addr)
{
	unsigned int mmu_asid;

	mmu_asid = read_aux_reg(ARC_REG_PID) & 0xff;

	/*
	 * At the time of a TLB miss/installation
	 *   - HW version needs to match SW version
	 *   - SW needs to have a valid ASID
	 */
	if (addr < 0x70000000 &&
	    ((mm_asid == MM_CTXT_NO_ASID) ||
	      (mmu_asid != (mm_asid & MM_CTXT_ASID_MASK))))
		print_asid_mismatch(mm_asid, mmu_asid, 0);
}
#endif