summaryrefslogtreecommitdiff
path: root/arch/powerpc/mm/pgtable_64.c
blob: 91bb8836825a6f516a0000525b9f44b69799d42b (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
/*
 *  This file contains ioremap and related functions for 64-bit machines.
 *
 *  Derived from arch/ppc64/mm/init.c
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Modifications by Paul Mackerras (PowerMac) (paulus@samba.org)
 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
 *    Copyright (C) 1996 Paul Mackerras
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  Dave Engebretsen <engebret@us.ibm.com>
 *      Rework for PPC64 port.
 *
 *  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 <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/export.h>
#include <linux/types.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/stddef.h>
#include <linux/vmalloc.h>
#include <linux/memblock.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>

#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/prom.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/smp.h>
#include <asm/machdep.h>
#include <asm/tlb.h>
#include <asm/processor.h>
#include <asm/cputable.h>
#include <asm/sections.h>
#include <asm/firmware.h>
#include <asm/dma.h>

#include "mmu_decl.h"

#define CREATE_TRACE_POINTS
#include <trace/events/thp.h>

/* Some sanity checking */
#if TASK_SIZE_USER64 > PGTABLE_RANGE
#error TASK_SIZE_USER64 exceeds pagetable range
#endif

#ifdef CONFIG_PPC_STD_MMU_64
#if TASK_SIZE_USER64 > (1UL << (ESID_BITS + SID_SHIFT))
#error TASK_SIZE_USER64 exceeds user VSID range
#endif
#endif

unsigned long ioremap_bot = IOREMAP_BASE;

#ifdef CONFIG_PPC_MMU_NOHASH
static __ref void *early_alloc_pgtable(unsigned long size)
{
	void *pt;

	pt = __va(memblock_alloc_base(size, size, __pa(MAX_DMA_ADDRESS)));
	memset(pt, 0, size);

	return pt;
}
#endif /* CONFIG_PPC_MMU_NOHASH */

/*
 * map_kernel_page currently only called by __ioremap
 * map_kernel_page adds an entry to the ioremap page table
 * and adds an entry to the HPT, possibly bolting it
 */
int map_kernel_page(unsigned long ea, unsigned long pa, int flags)
{
	pgd_t *pgdp;
	pud_t *pudp;
	pmd_t *pmdp;
	pte_t *ptep;

	if (slab_is_available()) {
		pgdp = pgd_offset_k(ea);
		pudp = pud_alloc(&init_mm, pgdp, ea);
		if (!pudp)
			return -ENOMEM;
		pmdp = pmd_alloc(&init_mm, pudp, ea);
		if (!pmdp)
			return -ENOMEM;
		ptep = pte_alloc_kernel(pmdp, ea);
		if (!ptep)
			return -ENOMEM;
		set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
							  __pgprot(flags)));
	} else {
#ifdef CONFIG_PPC_MMU_NOHASH
		pgdp = pgd_offset_k(ea);
#ifdef PUD_TABLE_SIZE
		if (pgd_none(*pgdp)) {
			pudp = early_alloc_pgtable(PUD_TABLE_SIZE);
			BUG_ON(pudp == NULL);
			pgd_populate(&init_mm, pgdp, pudp);
		}
#endif /* PUD_TABLE_SIZE */
		pudp = pud_offset(pgdp, ea);
		if (pud_none(*pudp)) {
			pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
			BUG_ON(pmdp == NULL);
			pud_populate(&init_mm, pudp, pmdp);
		}
		pmdp = pmd_offset(pudp, ea);
		if (!pmd_present(*pmdp)) {
			ptep = early_alloc_pgtable(PAGE_SIZE);
			BUG_ON(ptep == NULL);
			pmd_populate_kernel(&init_mm, pmdp, ptep);
		}
		ptep = pte_offset_kernel(pmdp, ea);
		set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
							  __pgprot(flags)));
#else /* CONFIG_PPC_MMU_NOHASH */
		/*
		 * If the mm subsystem is not fully up, we cannot create a
		 * linux page table entry for this mapping.  Simply bolt an
		 * entry in the hardware page table.
		 *
		 */
		if (htab_bolt_mapping(ea, ea + PAGE_SIZE, pa, flags,
				      mmu_io_psize, mmu_kernel_ssize)) {
			printk(KERN_ERR "Failed to do bolted mapping IO "
			       "memory at %016lx !\n", pa);
			return -ENOMEM;
		}
#endif /* !CONFIG_PPC_MMU_NOHASH */
	}

#ifdef CONFIG_PPC_BOOK3E_64
	/*
	 * With hardware tablewalk, a sync is needed to ensure that
	 * subsequent accesses see the PTE we just wrote.  Unlike userspace
	 * mappings, we can't tolerate spurious faults, so make sure
	 * the new PTE will be seen the first time.
	 */
	mb();
#else
	smp_wmb();
#endif
	return 0;
}


/**
 * __ioremap_at - Low level function to establish the page tables
 *                for an IO mapping
 */
void __iomem * __ioremap_at(phys_addr_t pa, void *ea, unsigned long size,
			    unsigned long flags)
{
	unsigned long i;

	/* Make sure we have the base flags */
	if ((flags & _PAGE_PRESENT) == 0)
		flags |= pgprot_val(PAGE_KERNEL);

	/* Non-cacheable page cannot be coherent */
	if (flags & _PAGE_NO_CACHE)
		flags &= ~_PAGE_COHERENT;

	/* We don't support the 4K PFN hack with ioremap */
	if (flags & _PAGE_4K_PFN)
		return NULL;

	WARN_ON(pa & ~PAGE_MASK);
	WARN_ON(((unsigned long)ea) & ~PAGE_MASK);
	WARN_ON(size & ~PAGE_MASK);

	for (i = 0; i < size; i += PAGE_SIZE)
		if (map_kernel_page((unsigned long)ea+i, pa+i, flags))
			return NULL;

	return (void __iomem *)ea;
}

/**
 * __iounmap_from - Low level function to tear down the page tables
 *                  for an IO mapping. This is used for mappings that
 *                  are manipulated manually, like partial unmapping of
 *                  PCI IOs or ISA space.
 */
void __iounmap_at(void *ea, unsigned long size)
{
	WARN_ON(((unsigned long)ea) & ~PAGE_MASK);
	WARN_ON(size & ~PAGE_MASK);

	unmap_kernel_range((unsigned long)ea, size);
}

void __iomem * __ioremap_caller(phys_addr_t addr, unsigned long size,
				unsigned long flags, void *caller)
{
	phys_addr_t paligned;
	void __iomem *ret;

	/*
	 * Choose an address to map it to.
	 * Once the imalloc system is running, we use it.
	 * Before that, we map using addresses going
	 * up from ioremap_bot.  imalloc will use
	 * the addresses from ioremap_bot through
	 * IMALLOC_END
	 * 
	 */
	paligned = addr & PAGE_MASK;
	size = PAGE_ALIGN(addr + size) - paligned;

	if ((size == 0) || (paligned == 0))
		return NULL;

	if (mem_init_done) {
		struct vm_struct *area;

		area = __get_vm_area_caller(size, VM_IOREMAP,
					    ioremap_bot, IOREMAP_END,
					    caller);
		if (area == NULL)
			return NULL;

		area->phys_addr = paligned;
		ret = __ioremap_at(paligned, area->addr, size, flags);
		if (!ret)
			vunmap(area->addr);
	} else {
		ret = __ioremap_at(paligned, (void *)ioremap_bot, size, flags);
		if (ret)
			ioremap_bot += size;
	}

	if (ret)
		ret += addr & ~PAGE_MASK;
	return ret;
}

void __iomem * __ioremap(phys_addr_t addr, unsigned long size,
			 unsigned long flags)
{
	return __ioremap_caller(addr, size, flags, __builtin_return_address(0));
}

void __iomem * ioremap(phys_addr_t addr, unsigned long size)
{
	unsigned long flags = _PAGE_NO_CACHE | _PAGE_GUARDED;
	void *caller = __builtin_return_address(0);

	if (ppc_md.ioremap)
		return ppc_md.ioremap(addr, size, flags, caller);
	return __ioremap_caller(addr, size, flags, caller);
}

void __iomem * ioremap_wc(phys_addr_t addr, unsigned long size)
{
	unsigned long flags = _PAGE_NO_CACHE;
	void *caller = __builtin_return_address(0);

	if (ppc_md.ioremap)
		return ppc_md.ioremap(addr, size, flags, caller);
	return __ioremap_caller(addr, size, flags, caller);
}

void __iomem * ioremap_prot(phys_addr_t addr, unsigned long size,
			     unsigned long flags)
{
	void *caller = __builtin_return_address(0);

	/* writeable implies dirty for kernel addresses */
	if (flags & _PAGE_RW)
		flags |= _PAGE_DIRTY;

	/* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
	flags &= ~(_PAGE_USER | _PAGE_EXEC);

#ifdef _PAGE_BAP_SR
	/* _PAGE_USER contains _PAGE_BAP_SR on BookE using the new PTE format
	 * which means that we just cleared supervisor access... oops ;-) This
	 * restores it
	 */
	flags |= _PAGE_BAP_SR;
#endif

	if (ppc_md.ioremap)
		return ppc_md.ioremap(addr, size, flags, caller);
	return __ioremap_caller(addr, size, flags, caller);
}


/*  
 * Unmap an IO region and remove it from imalloc'd list.
 * Access to IO memory should be serialized by driver.
 */
void __iounmap(volatile void __iomem *token)
{
	void *addr;

	if (!mem_init_done)
		return;
	
	addr = (void *) ((unsigned long __force)
			 PCI_FIX_ADDR(token) & PAGE_MASK);
	if ((unsigned long)addr < ioremap_bot) {
		printk(KERN_WARNING "Attempt to iounmap early bolted mapping"
		       " at 0x%p\n", addr);
		return;
	}
	vunmap(addr);
}

void iounmap(volatile void __iomem *token)
{
	if (ppc_md.iounmap)
		ppc_md.iounmap(token);
	else
		__iounmap(token);
}

EXPORT_SYMBOL(ioremap);
EXPORT_SYMBOL(ioremap_wc);
EXPORT_SYMBOL(ioremap_prot);
EXPORT_SYMBOL(__ioremap);
EXPORT_SYMBOL(__ioremap_at);
EXPORT_SYMBOL(iounmap);
EXPORT_SYMBOL(__iounmap);
EXPORT_SYMBOL(__iounmap_at);

#ifndef __PAGETABLE_PUD_FOLDED
/* 4 level page table */
struct page *pgd_page(pgd_t pgd)
{
	if (pgd_huge(pgd))
		return pte_page(pgd_pte(pgd));
	return virt_to_page(pgd_page_vaddr(pgd));
}
#endif

struct page *pud_page(pud_t pud)
{
	if (pud_huge(pud))
		return pte_page(pud_pte(pud));
	return virt_to_page(pud_page_vaddr(pud));
}

/*
 * For hugepage we have pfn in the pmd, we use PTE_RPN_SHIFT bits for flags
 * For PTE page, we have a PTE_FRAG_SIZE (4K) aligned virtual address.
 */
struct page *pmd_page(pmd_t pmd)
{
	if (pmd_trans_huge(pmd) || pmd_huge(pmd))
		return pfn_to_page(pmd_pfn(pmd));
	return virt_to_page(pmd_page_vaddr(pmd));
}

#ifdef CONFIG_PPC_64K_PAGES
static pte_t *get_from_cache(struct mm_struct *mm)
{
	void *pte_frag, *ret;

	spin_lock(&mm->page_table_lock);
	ret = mm->context.pte_frag;
	if (ret) {
		pte_frag = ret + PTE_FRAG_SIZE;
		/*
		 * If we have taken up all the fragments mark PTE page NULL
		 */
		if (((unsigned long)pte_frag & ~PAGE_MASK) == 0)
			pte_frag = NULL;
		mm->context.pte_frag = pte_frag;
	}
	spin_unlock(&mm->page_table_lock);
	return (pte_t *)ret;
}

static pte_t *__alloc_for_cache(struct mm_struct *mm, int kernel)
{
	void *ret = NULL;
	struct page *page = alloc_page(GFP_KERNEL | __GFP_NOTRACK |
				       __GFP_REPEAT | __GFP_ZERO);
	if (!page)
		return NULL;
	if (!kernel && !pgtable_page_ctor(page)) {
		__free_page(page);
		return NULL;
	}

	ret = page_address(page);
	spin_lock(&mm->page_table_lock);
	/*
	 * If we find pgtable_page set, we return
	 * the allocated page with single fragement
	 * count.
	 */
	if (likely(!mm->context.pte_frag)) {
		atomic_set(&page->_count, PTE_FRAG_NR);
		mm->context.pte_frag = ret + PTE_FRAG_SIZE;
	}
	spin_unlock(&mm->page_table_lock);

	return (pte_t *)ret;
}

pte_t *page_table_alloc(struct mm_struct *mm, unsigned long vmaddr, int kernel)
{
	pte_t *pte;

	pte = get_from_cache(mm);
	if (pte)
		return pte;

	return __alloc_for_cache(mm, kernel);
}

void page_table_free(struct mm_struct *mm, unsigned long *table, int kernel)
{
	struct page *page = virt_to_page(table);
	if (put_page_testzero(page)) {
		if (!kernel)
			pgtable_page_dtor(page);
		free_hot_cold_page(page, 0);
	}
}

#ifdef CONFIG_SMP
static void page_table_free_rcu(void *table)
{
	struct page *page = virt_to_page(table);
	if (put_page_testzero(page)) {
		pgtable_page_dtor(page);
		free_hot_cold_page(page, 0);
	}
}

void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int shift)
{
	unsigned long pgf = (unsigned long)table;

	BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
	pgf |= shift;
	tlb_remove_table(tlb, (void *)pgf);
}

void __tlb_remove_table(void *_table)
{
	void *table = (void *)((unsigned long)_table & ~MAX_PGTABLE_INDEX_SIZE);
	unsigned shift = (unsigned long)_table & MAX_PGTABLE_INDEX_SIZE;

	if (!shift)
		/* PTE page needs special handling */
		page_table_free_rcu(table);
	else {
		BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
		kmem_cache_free(PGT_CACHE(shift), table);
	}
}
#else
void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int shift)
{
	if (!shift) {
		/* PTE page needs special handling */
		struct page *page = virt_to_page(table);
		if (put_page_testzero(page)) {
			pgtable_page_dtor(page);
			free_hot_cold_page(page, 0);
		}
	} else {
		BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
		kmem_cache_free(PGT_CACHE(shift), table);
	}
}
#endif
#endif /* CONFIG_PPC_64K_PAGES */

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

/*
 * This is called when relaxing access to a hugepage. It's also called in the page
 * fault path when we don't hit any of the major fault cases, ie, a minor
 * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have
 * handled those two for us, we additionally deal with missing execute
 * permission here on some processors
 */
int pmdp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
			  pmd_t *pmdp, pmd_t entry, int dirty)
{
	int changed;
#ifdef CONFIG_DEBUG_VM
	WARN_ON(!pmd_trans_huge(*pmdp));
	assert_spin_locked(&vma->vm_mm->page_table_lock);
#endif
	changed = !pmd_same(*(pmdp), entry);
	if (changed) {
		__ptep_set_access_flags(pmdp_ptep(pmdp), pmd_pte(entry));
		/*
		 * Since we are not supporting SW TLB systems, we don't
		 * have any thing similar to flush_tlb_page_nohash()
		 */
	}
	return changed;
}

unsigned long pmd_hugepage_update(struct mm_struct *mm, unsigned long addr,
				  pmd_t *pmdp, unsigned long clr,
				  unsigned long set)
{

	unsigned long old, tmp;

#ifdef CONFIG_DEBUG_VM
	WARN_ON(!pmd_trans_huge(*pmdp));
	assert_spin_locked(&mm->page_table_lock);
#endif

#ifdef PTE_ATOMIC_UPDATES
	__asm__ __volatile__(
	"1:	ldarx	%0,0,%3\n\
		andi.	%1,%0,%6\n\
		bne-	1b \n\
		andc	%1,%0,%4 \n\
		or	%1,%1,%7\n\
		stdcx.	%1,0,%3 \n\
		bne-	1b"
	: "=&r" (old), "=&r" (tmp), "=m" (*pmdp)
	: "r" (pmdp), "r" (clr), "m" (*pmdp), "i" (_PAGE_BUSY), "r" (set)
	: "cc" );
#else
	old = pmd_val(*pmdp);
	*pmdp = __pmd((old & ~clr) | set);
#endif
	trace_hugepage_update(addr, old, clr, set);
	if (old & _PAGE_HASHPTE)
		hpte_do_hugepage_flush(mm, addr, pmdp, old);
	return old;
}

pmd_t pmdp_clear_flush(struct vm_area_struct *vma, unsigned long address,
		       pmd_t *pmdp)
{
	pmd_t pmd;

	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
	if (pmd_trans_huge(*pmdp)) {
		pmd = pmdp_get_and_clear(vma->vm_mm, address, pmdp);
	} else {
		/*
		 * khugepaged calls this for normal pmd
		 */
		pmd = *pmdp;
		pmd_clear(pmdp);
		/*
		 * Wait for all pending hash_page to finish. This is needed
		 * in case of subpage collapse. When we collapse normal pages
		 * to hugepage, we first clear the pmd, then invalidate all
		 * the PTE entries. The assumption here is that any low level
		 * page fault will see a none pmd and take the slow path that
		 * will wait on mmap_sem. But we could very well be in a
		 * hash_page with local ptep pointer value. Such a hash page
		 * can result in adding new HPTE entries for normal subpages.
		 * That means we could be modifying the page content as we
		 * copy them to a huge page. So wait for parallel hash_page
		 * to finish before invalidating HPTE entries. We can do this
		 * by sending an IPI to all the cpus and executing a dummy
		 * function there.
		 */
		kick_all_cpus_sync();
		/*
		 * Now invalidate the hpte entries in the range
		 * covered by pmd. This make sure we take a
		 * fault and will find the pmd as none, which will
		 * result in a major fault which takes mmap_sem and
		 * hence wait for collapse to complete. Without this
		 * the __collapse_huge_page_copy can result in copying
		 * the old content.
		 */
		flush_tlb_pmd_range(vma->vm_mm, &pmd, address);
	}
	return pmd;
}

int pmdp_test_and_clear_young(struct vm_area_struct *vma,
			      unsigned long address, pmd_t *pmdp)
{
	return __pmdp_test_and_clear_young(vma->vm_mm, address, pmdp);
}

/*
 * We currently remove entries from the hashtable regardless of whether
 * the entry was young or dirty. The generic routines only flush if the
 * entry was young or dirty which is not good enough.
 *
 * We should be more intelligent about this but for the moment we override
 * these functions and force a tlb flush unconditionally
 */
int pmdp_clear_flush_young(struct vm_area_struct *vma,
				  unsigned long address, pmd_t *pmdp)
{
	return __pmdp_test_and_clear_young(vma->vm_mm, address, pmdp);
}

/*
 * We mark the pmd splitting and invalidate all the hpte
 * entries for this hugepage.
 */
void pmdp_splitting_flush(struct vm_area_struct *vma,
			  unsigned long address, pmd_t *pmdp)
{
	unsigned long old, tmp;

	VM_BUG_ON(address & ~HPAGE_PMD_MASK);

#ifdef CONFIG_DEBUG_VM
	WARN_ON(!pmd_trans_huge(*pmdp));
	assert_spin_locked(&vma->vm_mm->page_table_lock);
#endif

#ifdef PTE_ATOMIC_UPDATES

	__asm__ __volatile__(
	"1:	ldarx	%0,0,%3\n\
		andi.	%1,%0,%6\n\
		bne-	1b \n\
		ori	%1,%0,%4 \n\
		stdcx.	%1,0,%3 \n\
		bne-	1b"
	: "=&r" (old), "=&r" (tmp), "=m" (*pmdp)
	: "r" (pmdp), "i" (_PAGE_SPLITTING), "m" (*pmdp), "i" (_PAGE_BUSY)
	: "cc" );
#else
	old = pmd_val(*pmdp);
	*pmdp = __pmd(old | _PAGE_SPLITTING);
#endif
	/*
	 * If we didn't had the splitting flag set, go and flush the
	 * HPTE entries.
	 */
	trace_hugepage_splitting(address, old);
	if (!(old & _PAGE_SPLITTING)) {
		/* We need to flush the hpte */
		if (old & _PAGE_HASHPTE)
			hpte_do_hugepage_flush(vma->vm_mm, address, pmdp, old);
	}
	/*
	 * This ensures that generic code that rely on IRQ disabling
	 * to prevent a parallel THP split work as expected.
	 */
	kick_all_cpus_sync();
}

/*
 * We want to put the pgtable in pmd and use pgtable for tracking
 * the base page size hptes
 */
void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
				pgtable_t pgtable)
{
	pgtable_t *pgtable_slot;
	assert_spin_locked(&mm->page_table_lock);
	/*
	 * we store the pgtable in the second half of PMD
	 */
	pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD;
	*pgtable_slot = pgtable;
	/*
	 * expose the deposited pgtable to other cpus.
	 * before we set the hugepage PTE at pmd level
	 * hash fault code looks at the deposted pgtable
	 * to store hash index values.
	 */
	smp_wmb();
}

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

	assert_spin_locked(&mm->page_table_lock);
	pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD;
	pgtable = *pgtable_slot;
	/*
	 * Once we withdraw, mark the entry NULL.
	 */
	*pgtable_slot = NULL;
	/*
	 * We store HPTE information in the deposited PTE fragment.
	 * zero out the content on withdraw.
	 */
	memset(pgtable, 0, PTE_FRAG_SIZE);
	return pgtable;
}

/*
 * set a new huge pmd. We should not be called for updating
 * an existing pmd entry. That should go via pmd_hugepage_update.
 */
void set_pmd_at(struct mm_struct *mm, unsigned long addr,
		pmd_t *pmdp, pmd_t pmd)
{
#ifdef CONFIG_DEBUG_VM
	WARN_ON((pmd_val(*pmdp) & (_PAGE_PRESENT | _PAGE_USER)) ==
		(_PAGE_PRESENT | _PAGE_USER));
	assert_spin_locked(&mm->page_table_lock);
	WARN_ON(!pmd_trans_huge(pmd));
#endif
	trace_hugepage_set_pmd(addr, pmd);
	return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
}

void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
		     pmd_t *pmdp)
{
	pmd_hugepage_update(vma->vm_mm, address, pmdp, _PAGE_PRESENT, 0);
}

/*
 * A linux hugepage PMD was changed and the corresponding hash table entries
 * neesd to be flushed.
 */
void hpte_do_hugepage_flush(struct mm_struct *mm, unsigned long addr,
			    pmd_t *pmdp, unsigned long old_pmd)
{
	int ssize;
	unsigned int psize;
	unsigned long vsid;
	unsigned long flags = 0;
	const struct cpumask *tmp;

	/* get the base page size,vsid and segment size */
#ifdef CONFIG_DEBUG_VM
	psize = get_slice_psize(mm, addr);
	BUG_ON(psize == MMU_PAGE_16M);
#endif
	if (old_pmd & _PAGE_COMBO)
		psize = MMU_PAGE_4K;
	else
		psize = MMU_PAGE_64K;

	if (!is_kernel_addr(addr)) {
		ssize = user_segment_size(addr);
		vsid = get_vsid(mm->context.id, addr, ssize);
		WARN_ON(vsid == 0);
	} else {
		vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
		ssize = mmu_kernel_ssize;
	}

	tmp = cpumask_of(smp_processor_id());
	if (cpumask_equal(mm_cpumask(mm), tmp))
		flags |= HPTE_LOCAL_UPDATE;

	return flush_hash_hugepage(vsid, addr, pmdp, psize, ssize, flags);
}

static pmd_t pmd_set_protbits(pmd_t pmd, pgprot_t pgprot)
{
	pmd_val(pmd) |= pgprot_val(pgprot);
	return pmd;
}

pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot)
{
	pmd_t pmd;
	/*
	 * For a valid pte, we would have _PAGE_PRESENT or _PAGE_FILE always
	 * set. We use this to check THP page at pmd level.
	 * leaf pte for huge page, bottom two bits != 00
	 */
	pmd_val(pmd) = pfn << PTE_RPN_SHIFT;
	pmd_val(pmd) |= _PAGE_THP_HUGE;
	pmd = pmd_set_protbits(pmd, pgprot);
	return pmd;
}

pmd_t mk_pmd(struct page *page, pgprot_t pgprot)
{
	return pfn_pmd(page_to_pfn(page), pgprot);
}

pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
{

	pmd_val(pmd) &= _HPAGE_CHG_MASK;
	pmd = pmd_set_protbits(pmd, newprot);
	return pmd;
}

/*
 * This is called at the end of handling a user page fault, when the
 * fault has been handled by updating a HUGE PMD entry in the linux page tables.
 * We use it to preload an HPTE into the hash table corresponding to
 * the updated linux HUGE PMD entry.
 */
void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
			  pmd_t *pmd)
{
	return;
}

pmd_t pmdp_get_and_clear(struct mm_struct *mm,
			 unsigned long addr, pmd_t *pmdp)
{
	pmd_t old_pmd;
	pgtable_t pgtable;
	unsigned long old;
	pgtable_t *pgtable_slot;

	old = pmd_hugepage_update(mm, addr, pmdp, ~0UL, 0);
	old_pmd = __pmd(old);
	/*
	 * We have pmd == none and we are holding page_table_lock.
	 * So we can safely go and clear the pgtable hash
	 * index info.
	 */
	pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD;
	pgtable = *pgtable_slot;
	/*
	 * Let's zero out old valid and hash index details
	 * hash fault look at them.
	 */
	memset(pgtable, 0, PTE_FRAG_SIZE);
	return old_pmd;
}

int has_transparent_hugepage(void)
{
	if (!mmu_has_feature(MMU_FTR_16M_PAGE))
		return 0;
	/*
	 * We support THP only if PMD_SIZE is 16MB.
	 */
	if (mmu_psize_defs[MMU_PAGE_16M].shift != PMD_SHIFT)
		return 0;
	/*
	 * We need to make sure that we support 16MB hugepage in a segement
	 * with base page size 64K or 4K. We only enable THP with a PAGE_SIZE
	 * of 64K.
	 */
	/*
	 * If we have 64K HPTE, we will be using that by default
	 */
	if (mmu_psize_defs[MMU_PAGE_64K].shift &&
	    (mmu_psize_defs[MMU_PAGE_64K].penc[MMU_PAGE_16M] == -1))
		return 0;
	/*
	 * Ok we only have 4K HPTE
	 */
	if (mmu_psize_defs[MMU_PAGE_4K].penc[MMU_PAGE_16M] == -1)
		return 0;

	return 1;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */