summaryrefslogtreecommitdiff
path: root/arch/powerpc/mm/tlb_low_64e.S
blob: 8b04c54e596f2a5a1bf770cb44013808eaf27246 (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
/*
 *  Low level TLB miss handlers for Book3E
 *
 *  Copyright (C) 2008-2009
 *      Ben. Herrenschmidt (benh@kernel.crashing.org), IBM Corp.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <asm/processor.h>
#include <asm/reg.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/cputable.h>
#include <asm/pgtable.h>
#include <asm/exception-64e.h>
#include <asm/ppc-opcode.h>

#ifdef CONFIG_PPC_64K_PAGES
#define VPTE_PMD_SHIFT	(PTE_INDEX_SIZE+1)
#else
#define VPTE_PMD_SHIFT	(PTE_INDEX_SIZE)
#endif
#define VPTE_PUD_SHIFT	(VPTE_PMD_SHIFT + PMD_INDEX_SIZE)
#define VPTE_PGD_SHIFT	(VPTE_PUD_SHIFT + PUD_INDEX_SIZE)
#define VPTE_INDEX_SIZE (VPTE_PGD_SHIFT + PGD_INDEX_SIZE)


/**********************************************************************
 *                                                                    *
 * TLB miss handling for Book3E with TLB reservation and HES support  *
 *                                                                    *
 **********************************************************************/


/* Data TLB miss */
	START_EXCEPTION(data_tlb_miss)
	TLB_MISS_PROLOG

	/* Now we handle the fault proper. We only save DEAR in normal
	 * fault case since that's the only interesting values here.
	 * We could probably also optimize by not saving SRR0/1 in the
	 * linear mapping case but I'll leave that for later
	 */
	mfspr	r14,SPRN_ESR
	mfspr	r16,SPRN_DEAR		/* get faulting address */
	srdi	r15,r16,60		/* get region */
	cmpldi	cr0,r15,0xc		/* linear mapping ? */
	TLB_MISS_STATS_SAVE_INFO
	beq	tlb_load_linear		/* yes -> go to linear map load */

	/* The page tables are mapped virtually linear. At this point, though,
	 * we don't know whether we are trying to fault in a first level
	 * virtual address or a virtual page table address. We can get that
	 * from bit 0x1 of the region ID which we have set for a page table
	 */
	andi.	r10,r15,0x1
	bne-	virt_page_table_tlb_miss

	std	r14,EX_TLB_ESR(r12);	/* save ESR */
	std	r16,EX_TLB_DEAR(r12);	/* save DEAR */

	 /* We need _PAGE_PRESENT and  _PAGE_ACCESSED set */
	li	r11,_PAGE_PRESENT
	oris	r11,r11,_PAGE_ACCESSED@h

	/* We do the user/kernel test for the PID here along with the RW test
	 */
	cmpldi	cr0,r15,0		/* Check for user region */

	/* We pre-test some combination of permissions to avoid double
	 * faults:
	 *
	 * We move the ESR:ST bit into the position of _PAGE_BAP_SW in the PTE
	 * ESR_ST   is 0x00800000
	 * _PAGE_BAP_SW is 0x00000010
	 * So the shift is >> 19. This tests for supervisor writeability.
	 * If the page happens to be supervisor writeable and not user
	 * writeable, we will take a new fault later, but that should be
	 * a rare enough case.
	 *
	 * We also move ESR_ST in _PAGE_DIRTY position
	 * _PAGE_DIRTY is 0x00001000 so the shift is >> 11
	 *
	 * MAS1 is preset for all we need except for TID that needs to
	 * be cleared for kernel translations
	 */
	rlwimi	r11,r14,32-19,27,27
	rlwimi	r11,r14,32-16,19,19
	beq	normal_tlb_miss
	/* XXX replace the RMW cycles with immediate loads + writes */
1:	mfspr	r10,SPRN_MAS1
	cmpldi	cr0,r15,8		/* Check for vmalloc region */
	rlwinm	r10,r10,0,16,1		/* Clear TID */
	mtspr	SPRN_MAS1,r10
	beq+	normal_tlb_miss

	/* We got a crappy address, just fault with whatever DEAR and ESR
	 * are here
	 */
	TLB_MISS_STATS_D(MMSTAT_TLB_MISS_NORM_FAULT)
	TLB_MISS_EPILOG_ERROR
	b	exc_data_storage_book3e

/* Instruction TLB miss */
	START_EXCEPTION(instruction_tlb_miss)
	TLB_MISS_PROLOG

	/* If we take a recursive fault, the second level handler may need
	 * to know whether we are handling a data or instruction fault in
	 * order to get to the right store fault handler. We provide that
	 * info by writing a crazy value in ESR in our exception frame
	 */
	li	r14,-1	/* store to exception frame is done later */

	/* Now we handle the fault proper. We only save DEAR in the non
	 * linear mapping case since we know the linear mapping case will
	 * not re-enter. We could indeed optimize and also not save SRR0/1
	 * in the linear mapping case but I'll leave that for later
	 *
	 * Faulting address is SRR0 which is already in r16
	 */
	srdi	r15,r16,60		/* get region */
	cmpldi	cr0,r15,0xc		/* linear mapping ? */
	TLB_MISS_STATS_SAVE_INFO
	beq	tlb_load_linear		/* yes -> go to linear map load */

	/* We do the user/kernel test for the PID here along with the RW test
	 */
	li	r11,_PAGE_PRESENT|_PAGE_EXEC	/* Base perm */
	oris	r11,r11,_PAGE_ACCESSED@h

	cmpldi	cr0,r15,0			/* Check for user region */
	std	r14,EX_TLB_ESR(r12)		/* write crazy -1 to frame */
	beq	normal_tlb_miss
	/* XXX replace the RMW cycles with immediate loads + writes */
1:	mfspr	r10,SPRN_MAS1
	cmpldi	cr0,r15,8			/* Check for vmalloc region */
	rlwinm	r10,r10,0,16,1			/* Clear TID */
	mtspr	SPRN_MAS1,r10
	beq+	normal_tlb_miss

	/* We got a crappy address, just fault */
	TLB_MISS_STATS_I(MMSTAT_TLB_MISS_NORM_FAULT)
	TLB_MISS_EPILOG_ERROR
	b	exc_instruction_storage_book3e

/*
 * This is the guts of the first-level TLB miss handler for direct
 * misses. We are entered with:
 *
 * r16 = faulting address
 * r15 = region ID
 * r14 = crap (free to use)
 * r13 = PACA
 * r12 = TLB exception frame in PACA
 * r11 = PTE permission mask
 * r10 = crap (free to use)
 */
normal_tlb_miss:
	/* So we first construct the page table address. We do that by
	 * shifting the bottom of the address (not the region ID) by
	 * PAGE_SHIFT-3, clearing the bottom 3 bits (get a PTE ptr) and
	 * or'ing the fourth high bit.
	 *
	 * NOTE: For 64K pages, we do things slightly differently in
	 * order to handle the weird page table format used by linux
	 */
	ori	r10,r15,0x1
#ifdef CONFIG_PPC_64K_PAGES
	/* For the top bits, 16 bytes per PTE */
	rldicl	r14,r16,64-(PAGE_SHIFT-4),PAGE_SHIFT-4+4
	/* Now create the bottom bits as 0 in position 0x8000 and
	 * the rest calculated for 8 bytes per PTE
	 */
	rldicl	r15,r16,64-(PAGE_SHIFT-3),64-15
	/* Insert the bottom bits in */
	rlwimi	r14,r15,0,16,31
#else
	rldicl	r14,r16,64-(PAGE_SHIFT-3),PAGE_SHIFT-3+4
#endif
	sldi	r15,r10,60
	clrrdi	r14,r14,3
	or	r10,r15,r14

BEGIN_MMU_FTR_SECTION
	/* Set the TLB reservation and seach for existing entry. Then load
	 * the entry.
	 */
	PPC_TLBSRX_DOT(0,r16)
	ld	r14,0(r10)
	beq	normal_tlb_miss_done
MMU_FTR_SECTION_ELSE
	ld	r14,0(r10)
ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_USE_TLBRSRV)

finish_normal_tlb_miss:
	/* Check if required permissions are met */
	andc.	r15,r11,r14
	bne-	normal_tlb_miss_access_fault

	/* Now we build the MAS:
	 *
	 * MAS 0   :	Fully setup with defaults in MAS4 and TLBnCFG
	 * MAS 1   :	Almost fully setup
	 *               - PID already updated by caller if necessary
	 *               - TSIZE need change if !base page size, not
	 *                 yet implemented for now
	 * MAS 2   :	Defaults not useful, need to be redone
	 * MAS 3+7 :	Needs to be done
	 *
	 * TODO: mix up code below for better scheduling
	 */
	clrrdi	r11,r16,12		/* Clear low crap in EA */
	rlwimi	r11,r14,32-19,27,31	/* Insert WIMGE */
	mtspr	SPRN_MAS2,r11

	/* Check page size, if not standard, update MAS1 */
	rldicl	r11,r14,64-8,64-8
#ifdef CONFIG_PPC_64K_PAGES
	cmpldi	cr0,r11,BOOK3E_PAGESZ_64K
#else
	cmpldi	cr0,r11,BOOK3E_PAGESZ_4K
#endif
	beq-	1f
	mfspr	r11,SPRN_MAS1
	rlwimi	r11,r14,31,21,24
	rlwinm	r11,r11,0,21,19
	mtspr	SPRN_MAS1,r11
1:
	/* Move RPN in position */
	rldicr	r11,r14,64-(PTE_RPN_SHIFT-PAGE_SHIFT),63-PAGE_SHIFT
	clrldi	r15,r11,12		/* Clear crap at the top */
	rlwimi	r15,r14,32-8,22,25	/* Move in U bits */
	rlwimi	r15,r14,32-2,26,31	/* Move in BAP bits */

	/* Mask out SW and UW if !DIRTY (XXX optimize this !) */
	andi.	r11,r14,_PAGE_DIRTY
	bne	1f
	li	r11,MAS3_SW|MAS3_UW
	andc	r15,r15,r11
1:
BEGIN_MMU_FTR_SECTION
	srdi	r16,r15,32
	mtspr	SPRN_MAS3,r15
	mtspr	SPRN_MAS7,r16
MMU_FTR_SECTION_ELSE
	mtspr	SPRN_MAS7_MAS3,r15
ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_USE_PAIRED_MAS)

	tlbwe

normal_tlb_miss_done:
	/* We don't bother with restoring DEAR or ESR since we know we are
	 * level 0 and just going back to userland. They are only needed
	 * if you are going to take an access fault
	 */
	TLB_MISS_STATS_X(MMSTAT_TLB_MISS_NORM_OK)
	TLB_MISS_EPILOG_SUCCESS
	rfi

normal_tlb_miss_access_fault:
	/* We need to check if it was an instruction miss */
	andi.	r10,r11,_PAGE_EXEC
	bne	1f
	ld	r14,EX_TLB_DEAR(r12)
	ld	r15,EX_TLB_ESR(r12)
	mtspr	SPRN_DEAR,r14
	mtspr	SPRN_ESR,r15
	TLB_MISS_STATS_D(MMSTAT_TLB_MISS_NORM_FAULT)
	TLB_MISS_EPILOG_ERROR
	b	exc_data_storage_book3e
1:	TLB_MISS_STATS_I(MMSTAT_TLB_MISS_NORM_FAULT)
	TLB_MISS_EPILOG_ERROR
	b	exc_instruction_storage_book3e


/*
 * This is the guts of the second-level TLB miss handler for direct
 * misses. We are entered with:
 *
 * r16 = virtual page table faulting address
 * r15 = region (top 4 bits of address)
 * r14 = crap (free to use)
 * r13 = PACA
 * r12 = TLB exception frame in PACA
 * r11 = crap (free to use)
 * r10 = crap (free to use)
 *
 * Note that this should only ever be called as a second level handler
 * with the current scheme when using SW load.
 * That means we can always get the original fault DEAR at
 * EX_TLB_DEAR-EX_TLB_SIZE(r12)
 *
 * It can be re-entered by the linear mapping miss handler. However, to
 * avoid too much complication, it will restart the whole fault at level
 * 0 so we don't care too much about clobbers
 *
 * XXX That code was written back when we couldn't clobber r14. We can now,
 * so we could probably optimize things a bit
 */
virt_page_table_tlb_miss:
	/* Are we hitting a kernel page table ? */
	andi.	r10,r15,0x8

	/* The cool thing now is that r10 contains 0 for user and 8 for kernel,
	 * and we happen to have the swapper_pg_dir at offset 8 from the user
	 * pgdir in the PACA :-).
	 */
	add	r11,r10,r13

	/* If kernel, we need to clear MAS1 TID */
	beq	1f
	/* XXX replace the RMW cycles with immediate loads + writes */
	mfspr	r10,SPRN_MAS1
	rlwinm	r10,r10,0,16,1			/* Clear TID */
	mtspr	SPRN_MAS1,r10
1:
BEGIN_MMU_FTR_SECTION
	/* Search if we already have a TLB entry for that virtual address, and
	 * if we do, bail out.
	 */
	PPC_TLBSRX_DOT(0,r16)
	beq	virt_page_table_tlb_miss_done
END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_TLBRSRV)

	/* Now, we need to walk the page tables. First check if we are in
	 * range.
	 */
	rldicl.	r10,r16,64-(VPTE_INDEX_SIZE+3),VPTE_INDEX_SIZE+3+4
	bne-	virt_page_table_tlb_miss_fault

	/* Get the PGD pointer */
	ld	r15,PACAPGD(r11)
	cmpldi	cr0,r15,0
	beq-	virt_page_table_tlb_miss_fault

	/* Get to PGD entry */
	rldicl	r11,r16,64-VPTE_PGD_SHIFT,64-PGD_INDEX_SIZE-3
	clrrdi	r10,r11,3
	ldx	r15,r10,r15
	cmpldi	cr0,r15,0
	beq	virt_page_table_tlb_miss_fault

#ifndef CONFIG_PPC_64K_PAGES
	/* Get to PUD entry */
	rldicl	r11,r16,64-VPTE_PUD_SHIFT,64-PUD_INDEX_SIZE-3
	clrrdi	r10,r11,3
	ldx	r15,r10,r15
	cmpldi	cr0,r15,0
	beq	virt_page_table_tlb_miss_fault
#endif /* CONFIG_PPC_64K_PAGES */

	/* Get to PMD entry */
	rldicl	r11,r16,64-VPTE_PMD_SHIFT,64-PMD_INDEX_SIZE-3
	clrrdi	r10,r11,3
	ldx	r15,r10,r15
	cmpldi	cr0,r15,0
	beq	virt_page_table_tlb_miss_fault

	/* Ok, we're all right, we can now create a kernel translation for
	 * a 4K or 64K page from r16 -> r15.
	 */
	/* Now we build the MAS:
	 *
	 * MAS 0   :	Fully setup with defaults in MAS4 and TLBnCFG
	 * MAS 1   :	Almost fully setup
	 *               - PID already updated by caller if necessary
	 *               - TSIZE for now is base page size always
	 * MAS 2   :	Use defaults
	 * MAS 3+7 :	Needs to be done
	 *
	 * So we only do MAS 2 and 3 for now...
	 */
	clrldi	r11,r15,4		/* remove region ID from RPN */
	ori	r10,r11,1		/* Or-in SR */

BEGIN_MMU_FTR_SECTION
	srdi	r16,r10,32
	mtspr	SPRN_MAS3,r10
	mtspr	SPRN_MAS7,r16
MMU_FTR_SECTION_ELSE
	mtspr	SPRN_MAS7_MAS3,r10
ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_USE_PAIRED_MAS)

	tlbwe

BEGIN_MMU_FTR_SECTION
virt_page_table_tlb_miss_done:

	/* We have overriden MAS2:EPN but currently our primary TLB miss
	 * handler will always restore it so that should not be an issue,
	 * if we ever optimize the primary handler to not write MAS2 on
	 * some cases, we'll have to restore MAS2:EPN here based on the
	 * original fault's DEAR. If we do that we have to modify the
	 * ITLB miss handler to also store SRR0 in the exception frame
	 * as DEAR.
	 *
	 * However, one nasty thing we did is we cleared the reservation
	 * (well, potentially we did). We do a trick here thus if we
	 * are not a level 0 exception (we interrupted the TLB miss) we
	 * offset the return address by -4 in order to replay the tlbsrx
	 * instruction there
	 */
	subf	r10,r13,r12
	cmpldi	cr0,r10,PACA_EXTLB+EX_TLB_SIZE
	bne-	1f
	ld	r11,PACA_EXTLB+EX_TLB_SIZE+EX_TLB_SRR0(r13)
	addi	r10,r11,-4
	std	r10,PACA_EXTLB+EX_TLB_SIZE+EX_TLB_SRR0(r13)
1:
END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_TLBRSRV)
	/* Return to caller, normal case */
	TLB_MISS_STATS_X(MMSTAT_TLB_MISS_PT_OK);
	TLB_MISS_EPILOG_SUCCESS
	rfi

virt_page_table_tlb_miss_fault:
	/* If we fault here, things are a little bit tricky. We need to call
	 * either data or instruction store fault, and we need to retreive
	 * the original fault address and ESR (for data).
	 *
	 * The thing is, we know that in normal circumstances, this is
	 * always called as a second level tlb miss for SW load or as a first
	 * level TLB miss for HW load, so we should be able to peek at the
	 * relevant informations in the first exception frame in the PACA.
	 *
	 * However, we do need to double check that, because we may just hit
	 * a stray kernel pointer or a userland attack trying to hit those
	 * areas. If that is the case, we do a data fault. (We can't get here
	 * from an instruction tlb miss anyway).
	 *
	 * Note also that when going to a fault, we must unwind the previous
	 * level as well. Since we are doing that, we don't need to clear or
	 * restore the TLB reservation neither.
	 */
	subf	r10,r13,r12
	cmpldi	cr0,r10,PACA_EXTLB+EX_TLB_SIZE
	bne-	virt_page_table_tlb_miss_whacko_fault

	/* We dig the original DEAR and ESR from slot 0 */
	ld	r15,EX_TLB_DEAR+PACA_EXTLB(r13)
	ld	r16,EX_TLB_ESR+PACA_EXTLB(r13)

	/* We check for the "special" ESR value for instruction faults */
	cmpdi	cr0,r16,-1
	beq	1f
	mtspr	SPRN_DEAR,r15
	mtspr	SPRN_ESR,r16
	TLB_MISS_STATS_D(MMSTAT_TLB_MISS_PT_FAULT);
	TLB_MISS_EPILOG_ERROR
	b	exc_data_storage_book3e
1:	TLB_MISS_STATS_I(MMSTAT_TLB_MISS_PT_FAULT);
	TLB_MISS_EPILOG_ERROR
	b	exc_instruction_storage_book3e

virt_page_table_tlb_miss_whacko_fault:
	/* The linear fault will restart everything so ESR and DEAR will
	 * not have been clobbered, let's just fault with what we have
	 */
	TLB_MISS_STATS_X(MMSTAT_TLB_MISS_PT_FAULT);
	TLB_MISS_EPILOG_ERROR
	b	exc_data_storage_book3e


/**************************************************************
 *                                                            *
 * TLB miss handling for Book3E with hw page table support    *
 *                                                            *
 **************************************************************/


/* Data TLB miss */
	START_EXCEPTION(data_tlb_miss_htw)
	TLB_MISS_PROLOG

	/* Now we handle the fault proper. We only save DEAR in normal
	 * fault case since that's the only interesting values here.
	 * We could probably also optimize by not saving SRR0/1 in the
	 * linear mapping case but I'll leave that for later
	 */
	mfspr	r14,SPRN_ESR
	mfspr	r16,SPRN_DEAR		/* get faulting address */
	srdi	r11,r16,60		/* get region */
	cmpldi	cr0,r11,0xc		/* linear mapping ? */
	TLB_MISS_STATS_SAVE_INFO
	beq	tlb_load_linear		/* yes -> go to linear map load */

	/* We do the user/kernel test for the PID here along with the RW test
	 */
	cmpldi	cr0,r11,0		/* Check for user region */
	ld	r15,PACAPGD(r13)	/* Load user pgdir */
	beq	htw_tlb_miss

	/* XXX replace the RMW cycles with immediate loads + writes */
1:	mfspr	r10,SPRN_MAS1
	cmpldi	cr0,r11,8		/* Check for vmalloc region */
	rlwinm	r10,r10,0,16,1		/* Clear TID */
	mtspr	SPRN_MAS1,r10
	ld	r15,PACA_KERNELPGD(r13)	/* Load kernel pgdir */
	beq+	htw_tlb_miss

	/* We got a crappy address, just fault with whatever DEAR and ESR
	 * are here
	 */
	TLB_MISS_STATS_D(MMSTAT_TLB_MISS_NORM_FAULT)
	TLB_MISS_EPILOG_ERROR
	b	exc_data_storage_book3e

/* Instruction TLB miss */
	START_EXCEPTION(instruction_tlb_miss_htw)
	TLB_MISS_PROLOG

	/* If we take a recursive fault, the second level handler may need
	 * to know whether we are handling a data or instruction fault in
	 * order to get to the right store fault handler. We provide that
	 * info by keeping a crazy value for ESR in r14
	 */
	li	r14,-1	/* store to exception frame is done later */

	/* Now we handle the fault proper. We only save DEAR in the non
	 * linear mapping case since we know the linear mapping case will
	 * not re-enter. We could indeed optimize and also not save SRR0/1
	 * in the linear mapping case but I'll leave that for later
	 *
	 * Faulting address is SRR0 which is already in r16
	 */
	srdi	r11,r16,60		/* get region */
	cmpldi	cr0,r11,0xc		/* linear mapping ? */
	TLB_MISS_STATS_SAVE_INFO
	beq	tlb_load_linear		/* yes -> go to linear map load */

	/* We do the user/kernel test for the PID here along with the RW test
	 */
	cmpldi	cr0,r11,0			/* Check for user region */
	ld	r15,PACAPGD(r13)		/* Load user pgdir */
	beq	htw_tlb_miss

	/* XXX replace the RMW cycles with immediate loads + writes */
1:	mfspr	r10,SPRN_MAS1
	cmpldi	cr0,r11,8			/* Check for vmalloc region */
	rlwinm	r10,r10,0,16,1			/* Clear TID */
	mtspr	SPRN_MAS1,r10
	ld	r15,PACA_KERNELPGD(r13)		/* Load kernel pgdir */
	beq+	htw_tlb_miss

	/* We got a crappy address, just fault */
	TLB_MISS_STATS_I(MMSTAT_TLB_MISS_NORM_FAULT)
	TLB_MISS_EPILOG_ERROR
	b	exc_instruction_storage_book3e


/*
 * This is the guts of the second-level TLB miss handler for direct
 * misses. We are entered with:
 *
 * r16 = virtual page table faulting address
 * r15 = PGD pointer
 * r14 = ESR
 * r13 = PACA
 * r12 = TLB exception frame in PACA
 * r11 = crap (free to use)
 * r10 = crap (free to use)
 *
 * It can be re-entered by the linear mapping miss handler. However, to
 * avoid too much complication, it will save/restore things for us
 */
htw_tlb_miss:
	/* Search if we already have a TLB entry for that virtual address, and
	 * if we do, bail out.
	 *
	 * MAS1:IND should be already set based on MAS4
	 */
	PPC_TLBSRX_DOT(0,r16)
	beq	htw_tlb_miss_done

	/* Now, we need to walk the page tables. First check if we are in
	 * range.
	 */
	rldicl.	r10,r16,64-PGTABLE_EADDR_SIZE,PGTABLE_EADDR_SIZE+4
	bne-	htw_tlb_miss_fault

	/* Get the PGD pointer */
	cmpldi	cr0,r15,0
	beq-	htw_tlb_miss_fault

	/* Get to PGD entry */
	rldicl	r11,r16,64-(PGDIR_SHIFT-3),64-PGD_INDEX_SIZE-3
	clrrdi	r10,r11,3
	ldx	r15,r10,r15
	cmpldi	cr0,r15,0
	beq	htw_tlb_miss_fault

#ifndef CONFIG_PPC_64K_PAGES
	/* Get to PUD entry */
	rldicl	r11,r16,64-(PUD_SHIFT-3),64-PUD_INDEX_SIZE-3
	clrrdi	r10,r11,3
	ldx	r15,r10,r15
	cmpldi	cr0,r15,0
	beq	htw_tlb_miss_fault
#endif /* CONFIG_PPC_64K_PAGES */

	/* Get to PMD entry */
	rldicl	r11,r16,64-(PMD_SHIFT-3),64-PMD_INDEX_SIZE-3
	clrrdi	r10,r11,3
	ldx	r15,r10,r15
	cmpldi	cr0,r15,0
	beq	htw_tlb_miss_fault

	/* Ok, we're all right, we can now create an indirect entry for
	 * a 1M or 256M page.
	 *
	 * The last trick is now that because we use "half" pages for
	 * the HTW (1M IND is 2K and 256M IND is 32K) we need to account
	 * for an added LSB bit to the RPN. For 64K pages, there is no
	 * problem as we already use 32K arrays (half PTE pages), but for
	 * 4K page we need to extract a bit from the virtual address and
	 * insert it into the "PA52" bit of the RPN.
	 */
#ifndef CONFIG_PPC_64K_PAGES
	rlwimi	r15,r16,32-9,20,20
#endif
	/* Now we build the MAS:
	 *
	 * MAS 0   :	Fully setup with defaults in MAS4 and TLBnCFG
	 * MAS 1   :	Almost fully setup
	 *               - PID already updated by caller if necessary
	 *               - TSIZE for now is base ind page size always
	 * MAS 2   :	Use defaults
	 * MAS 3+7 :	Needs to be done
	 */
#ifdef CONFIG_PPC_64K_PAGES
	ori	r10,r15,(BOOK3E_PAGESZ_64K << MAS3_SPSIZE_SHIFT)
#else
	ori	r10,r15,(BOOK3E_PAGESZ_4K << MAS3_SPSIZE_SHIFT)
#endif

BEGIN_MMU_FTR_SECTION
	srdi	r16,r10,32
	mtspr	SPRN_MAS3,r10
	mtspr	SPRN_MAS7,r16
MMU_FTR_SECTION_ELSE
	mtspr	SPRN_MAS7_MAS3,r10
ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_USE_PAIRED_MAS)

	tlbwe

htw_tlb_miss_done:
	/* We don't bother with restoring DEAR or ESR since we know we are
	 * level 0 and just going back to userland. They are only needed
	 * if you are going to take an access fault
	 */
	TLB_MISS_STATS_X(MMSTAT_TLB_MISS_PT_OK)
	TLB_MISS_EPILOG_SUCCESS
	rfi

htw_tlb_miss_fault:
	/* We need to check if it was an instruction miss. We know this
	 * though because r14 would contain -1
	 */
	cmpdi	cr0,r14,-1
	beq	1f
	mtspr	SPRN_DEAR,r16
	mtspr	SPRN_ESR,r14
	TLB_MISS_STATS_D(MMSTAT_TLB_MISS_PT_FAULT)
	TLB_MISS_EPILOG_ERROR
	b	exc_data_storage_book3e
1:	TLB_MISS_STATS_I(MMSTAT_TLB_MISS_PT_FAULT)
	TLB_MISS_EPILOG_ERROR
	b	exc_instruction_storage_book3e

/*
 * This is the guts of "any" level TLB miss handler for kernel linear
 * mapping misses. We are entered with:
 *
 *
 * r16 = faulting address
 * r15 = crap (free to use)
 * r14 = ESR (data) or -1 (instruction)
 * r13 = PACA
 * r12 = TLB exception frame in PACA
 * r11 = crap (free to use)
 * r10 = crap (free to use)
 *
 * In addition we know that we will not re-enter, so in theory, we could
 * use a simpler epilog not restoring SRR0/1 etc.. but we'll do that later.
 *
 * We also need to be careful about MAS registers here & TLB reservation,
 * as we know we'll have clobbered them if we interrupt the main TLB miss
 * handlers in which case we probably want to do a full restart at level
 * 0 rather than saving / restoring the MAS.
 *
 * Note: If we care about performance of that core, we can easily shuffle
 *       a few things around
 */
tlb_load_linear:
	/* For now, we assume the linear mapping is contiguous and stops at
	 * linear_map_top. We also assume the size is a multiple of 1G, thus
	 * we only use 1G pages for now. That might have to be changed in a
	 * final implementation, especially when dealing with hypervisors
	 */
	ld	r11,PACATOC(r13)
	ld	r11,linear_map_top@got(r11)
	ld	r10,0(r11)
	cmpld	cr0,r10,r16
	bge	tlb_load_linear_fault

	/* MAS1 need whole new setup. */
	li	r15,(BOOK3E_PAGESZ_1GB<<MAS1_TSIZE_SHIFT)
	oris	r15,r15,MAS1_VALID@h	/* MAS1 needs V and TSIZE */
	mtspr	SPRN_MAS1,r15

	/* Already somebody there ? */
	PPC_TLBSRX_DOT(0,r16)
	beq	tlb_load_linear_done

	/* Now we build the remaining MAS. MAS0 and 2 should be fine
	 * with their defaults, which leaves us with MAS 3 and 7. The
	 * mapping is linear, so we just take the address, clear the
	 * region bits, and or in the permission bits which are currently
	 * hard wired
	 */
	clrrdi	r10,r16,30		/* 1G page index */
	clrldi	r10,r10,4		/* clear region bits */
	ori	r10,r10,MAS3_SR|MAS3_SW|MAS3_SX

BEGIN_MMU_FTR_SECTION
	srdi	r16,r10,32
	mtspr	SPRN_MAS3,r10
	mtspr	SPRN_MAS7,r16
MMU_FTR_SECTION_ELSE
	mtspr	SPRN_MAS7_MAS3,r10
ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_USE_PAIRED_MAS)

	tlbwe

tlb_load_linear_done:
	/* We use the "error" epilog for success as we do want to
	 * restore to the initial faulting context, whatever it was.
	 * We do that because we can't resume a fault within a TLB
	 * miss handler, due to MAS and TLB reservation being clobbered.
	 */
	TLB_MISS_STATS_X(MMSTAT_TLB_MISS_LINEAR)
	TLB_MISS_EPILOG_ERROR
	rfi

tlb_load_linear_fault:
	/* We keep the DEAR and ESR around, this shouldn't have happened */
	cmpdi	cr0,r14,-1
	beq	1f
	TLB_MISS_EPILOG_ERROR_SPECIAL
	b	exc_data_storage_book3e
1:	TLB_MISS_EPILOG_ERROR_SPECIAL
	b	exc_instruction_storage_book3e


#ifdef CONFIG_BOOK3E_MMU_TLB_STATS
.tlb_stat_inc:
1:	ldarx	r8,0,r9
	addi	r8,r8,1
	stdcx.	r8,0,r9
	bne-	1b
	blr
#endif