aboutsummaryrefslogtreecommitdiffstats
path: root/arch/powerpc/mm/hugetlbpage.c
blob: c94dc71af989277007c33ee3f804ee561d944c33 (plain) (blame)
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
/*
 * PPC64 (POWER4) Huge TLB Page Support for Kernel.
 *
 * Copyright (C) 2003 David Gibson, IBM Corporation.
 *
 * Based on the IA-32 version:
 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/sysctl.h>
#include <asm/mman.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/machdep.h>
#include <asm/cputable.h>
#include <asm/spu.h>

#define HPAGE_SHIFT_64K	16
#define HPAGE_SHIFT_16M	24

#define NUM_LOW_AREAS	(0x100000000UL >> SID_SHIFT)
#define NUM_HIGH_AREAS	(PGTABLE_RANGE >> HTLB_AREA_SHIFT)

unsigned int hugepte_shift;
#define PTRS_PER_HUGEPTE	(1 << hugepte_shift)
#define HUGEPTE_TABLE_SIZE	(sizeof(pte_t) << hugepte_shift)

#define HUGEPD_SHIFT		(HPAGE_SHIFT + hugepte_shift)
#define HUGEPD_SIZE		(1UL << HUGEPD_SHIFT)
#define HUGEPD_MASK		(~(HUGEPD_SIZE-1))

#define huge_pgtable_cache	(pgtable_cache[HUGEPTE_CACHE_NUM])

/* Flag to mark huge PD pointers.  This means pmd_bad() and pud_bad()
 * will choke on pointers to hugepte tables, which is handy for
 * catching screwups early. */
#define HUGEPD_OK	0x1

typedef struct { unsigned long pd; } hugepd_t;

#define hugepd_none(hpd)	((hpd).pd == 0)

static inline pte_t *hugepd_page(hugepd_t hpd)
{
	BUG_ON(!(hpd.pd & HUGEPD_OK));
	return (pte_t *)(hpd.pd & ~HUGEPD_OK);
}

static inline pte_t *hugepte_offset(hugepd_t *hpdp, unsigned long addr)
{
	unsigned long idx = ((addr >> HPAGE_SHIFT) & (PTRS_PER_HUGEPTE-1));
	pte_t *dir = hugepd_page(*hpdp);

	return dir + idx;
}

static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
			   unsigned long address)
{
	pte_t *new = kmem_cache_alloc(huge_pgtable_cache,
				      GFP_KERNEL|__GFP_REPEAT);

	if (! new)
		return -ENOMEM;

	spin_lock(&mm->page_table_lock);
	if (!hugepd_none(*hpdp))
		kmem_cache_free(huge_pgtable_cache, new);
	else
		hpdp->pd = (unsigned long)new | HUGEPD_OK;
	spin_unlock(&mm->page_table_lock);
	return 0;
}

/* Base page size affects how we walk hugetlb page tables */
#ifdef CONFIG_PPC_64K_PAGES
#define hpmd_offset(pud, addr)		pmd_offset(pud, addr)
#define hpmd_alloc(mm, pud, addr)	pmd_alloc(mm, pud, addr)
#else
static inline
pmd_t *hpmd_offset(pud_t *pud, unsigned long addr)
{
	if (HPAGE_SHIFT == HPAGE_SHIFT_64K)
		return pmd_offset(pud, addr);
	else
		return (pmd_t *) pud;
}
static inline
pmd_t *hpmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long addr)
{
	if (HPAGE_SHIFT == HPAGE_SHIFT_64K)
		return pmd_alloc(mm, pud, addr);
	else
		return (pmd_t *) pud;
}
#endif

/* Modelled after find_linux_pte() */
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
{
	pgd_t *pg;
	pud_t *pu;
	pmd_t *pm;

	BUG_ON(get_slice_psize(mm, addr) != mmu_huge_psize);

	addr &= HPAGE_MASK;

	pg = pgd_offset(mm, addr);
	if (!pgd_none(*pg)) {
		pu = pud_offset(pg, addr);
		if (!pud_none(*pu)) {
			pm = hpmd_offset(pu, addr);
			if (!pmd_none(*pm))
				return hugepte_offset((hugepd_t *)pm, addr);
		}
	}

	return NULL;
}

pte_t *huge_pte_alloc(struct mm_struct *mm,
			unsigned long addr, unsigned long sz)
{
	pgd_t *pg;
	pud_t *pu;
	pmd_t *pm;
	hugepd_t *hpdp = NULL;

	BUG_ON(get_slice_psize(mm, addr) != mmu_huge_psize);

	addr &= HPAGE_MASK;

	pg = pgd_offset(mm, addr);
	pu = pud_alloc(mm, pg, addr);

	if (pu) {
		pm = hpmd_alloc(mm, pu, addr);
		if (pm)
			hpdp = (hugepd_t *)pm;
	}

	if (! hpdp)
		return NULL;

	if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr))
		return NULL;

	return hugepte_offset(hpdp, addr);
}

int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
	return 0;
}

static void free_hugepte_range(struct mmu_gather *tlb, hugepd_t *hpdp)
{
	pte_t *hugepte = hugepd_page(*hpdp);

	hpdp->pd = 0;
	tlb->need_flush = 1;
	pgtable_free_tlb(tlb, pgtable_free_cache(hugepte, HUGEPTE_CACHE_NUM,
						 PGF_CACHENUM_MASK));
}

static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
				   unsigned long addr, unsigned long end,
				   unsigned long floor, unsigned long ceiling)
{
	pmd_t *pmd;
	unsigned long next;
	unsigned long start;

	start = addr;
	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none(*pmd))
			continue;
		free_hugepte_range(tlb, (hugepd_t *)pmd);
	} while (pmd++, addr = next, addr != end);

	start &= PUD_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PUD_MASK;
		if (!ceiling)
			return;
	}
	if (end - 1 > ceiling - 1)
		return;

	pmd = pmd_offset(pud, start);
	pud_clear(pud);
	pmd_free_tlb(tlb, pmd);
}

static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
				   unsigned long addr, unsigned long end,
				   unsigned long floor, unsigned long ceiling)
{
	pud_t *pud;
	unsigned long next;
	unsigned long start;

	start = addr;
	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
#ifdef CONFIG_PPC_64K_PAGES
		if (pud_none_or_clear_bad(pud))
			continue;
		hugetlb_free_pmd_range(tlb, pud, addr, next, floor, ceiling);
#else
		if (HPAGE_SHIFT == HPAGE_SHIFT_64K) {
			if (pud_none_or_clear_bad(pud))
				continue;
			hugetlb_free_pmd_range(tlb, pud, addr, next, floor, ceiling);
		} else {
			if (pud_none(*pud))
				continue;
			free_hugepte_range(tlb, (hugepd_t *)pud);
		}
#endif
	} while (pud++, addr = next, addr != end);

	start &= PGDIR_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PGDIR_MASK;
		if (!ceiling)
			return;
	}
	if (end - 1 > ceiling - 1)
		return;

	pud = pud_offset(pgd, start);
	pgd_clear(pgd);
	pud_free_tlb(tlb, pud);
}

/*
 * This function frees user-level page tables of a process.
 *
 * Must be called with pagetable lock held.
 */
void hugetlb_free_pgd_range(struct mmu_gather *tlb,
			    unsigned long addr, unsigned long end,
			    unsigned long floor, unsigned long ceiling)
{
	pgd_t *pgd;
	unsigned long next;
	unsigned long start;

	/*
	 * Comments below take from the normal free_pgd_range().  They
	 * apply here too.  The tests against HUGEPD_MASK below are
	 * essential, because we *don't* test for this at the bottom
	 * level.  Without them we'll attempt to free a hugepte table
	 * when we unmap just part of it, even if there are other
	 * active mappings using it.
	 *
	 * The next few lines have given us lots of grief...
	 *
	 * Why are we testing HUGEPD* at this top level?  Because
	 * often there will be no work to do at all, and we'd prefer
	 * not to go all the way down to the bottom just to discover
	 * that.
	 *
	 * Why all these "- 1"s?  Because 0 represents both the bottom
	 * of the address space and the top of it (using -1 for the
	 * top wouldn't help much: the masks would do the wrong thing).
	 * The rule is that addr 0 and floor 0 refer to the bottom of
	 * the address space, but end 0 and ceiling 0 refer to the top
	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
	 * that end 0 case should be mythical).
	 *
	 * Wherever addr is brought up or ceiling brought down, we
	 * must be careful to reject "the opposite 0" before it
	 * confuses the subsequent tests.  But what about where end is
	 * brought down by HUGEPD_SIZE below? no, end can't go down to
	 * 0 there.
	 *
	 * Whereas we round start (addr) and ceiling down, by different
	 * masks at different levels, in order to test whether a table
	 * now has no other vmas using it, so can be freed, we don't
	 * bother to round floor or end up - the tests don't need that.
	 */

	addr &= HUGEPD_MASK;
	if (addr < floor) {
		addr += HUGEPD_SIZE;
		if (!addr)
			return;
	}
	if (ceiling) {
		ceiling &= HUGEPD_MASK;
		if (!ceiling)
			return;
	}
	if (end - 1 > ceiling - 1)
		end -= HUGEPD_SIZE;
	if (addr > end - 1)
		return;

	start = addr;
	pgd = pgd_offset(tlb->mm, addr);
	do {
		BUG_ON(get_slice_psize(tlb->mm, addr) != mmu_huge_psize);
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			continue;
		hugetlb_free_pud_range(tlb, pgd, addr, next, floor, ceiling);
	} while (pgd++, addr = next, addr != end);
}

void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
		     pte_t *ptep, pte_t pte)
{
	if (pte_present(*ptep)) {
		/* We open-code pte_clear because we need to pass the right
		 * argument to hpte_need_flush (huge / !huge). Might not be
		 * necessary anymore if we make hpte_need_flush() get the
		 * page size from the slices
		 */
		pte_update(mm, addr & HPAGE_MASK, ptep, ~0UL, 1);
	}
	*ptep = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
}

pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
			      pte_t *ptep)
{
	unsigned long old = pte_update(mm, addr, ptep, ~0UL, 1);
	return __pte(old);
}

struct page *
follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
{
	pte_t *ptep;
	struct page *page;

	if (get_slice_psize(mm, address) != mmu_huge_psize)
		return ERR_PTR(-EINVAL);

	ptep = huge_pte_offset(mm, address);
	page = pte_page(*ptep);
	if (page)
		page += (address % HPAGE_SIZE) / PAGE_SIZE;

	return page;
}

int pmd_huge(pmd_t pmd)
{
	return 0;
}

struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
		pmd_t *pmd, int write)
{
	BUG();
	return NULL;
}


unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
					unsigned long len, unsigned long pgoff,
					unsigned long flags)
{
	return slice_get_unmapped_area(addr, len, flags,
				       mmu_huge_psize, 1, 0);
}

/*
 * Called by asm hashtable.S for doing lazy icache flush
 */
static unsigned int hash_huge_page_do_lazy_icache(unsigned long rflags,
						  pte_t pte, int trap)
{
	struct page *page;
	int i;

	if (!pfn_valid(pte_pfn(pte)))
		return rflags;

	page = pte_page(pte);

	/* page is dirty */
	if (!test_bit(PG_arch_1, &page->flags) && !PageReserved(page)) {
		if (trap == 0x400) {
			for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++)
				__flush_dcache_icache(page_address(page+i));
			set_bit(PG_arch_1, &page->flags);
		} else {
			rflags |= HPTE_R_N;
		}
	}
	return rflags;
}

int hash_huge_page(struct mm_struct *mm, unsigned long access,
		   unsigned long ea, unsigned long vsid, int local,
		   unsigned long trap)
{
	pte_t *ptep;
	unsigned long old_pte, new_pte;
	unsigned long va, rflags, pa;
	long slot;
	int err = 1;
	int ssize = user_segment_size(ea);

	ptep = huge_pte_offset(mm, ea);

	/* Search the Linux page table for a match with va */
	va = hpt_va(ea, vsid, ssize);

	/*
	 * If no pte found or not present, send the problem up to
	 * do_page_fault
	 */
	if (unlikely(!ptep || pte_none(*ptep)))
		goto out;

	/* 
	 * Check the user's access rights to the page.  If access should be
	 * prevented then send the problem up to do_page_fault.
	 */
	if (unlikely(access & ~pte_val(*ptep)))
		goto out;
	/*
	 * At this point, we have a pte (old_pte) which can be used to build
	 * or update an HPTE. There are 2 cases:
	 *
	 * 1. There is a valid (present) pte with no associated HPTE (this is 
	 *	the most common case)
	 * 2. There is a valid (present) pte with an associated HPTE. The
	 *	current values of the pp bits in the HPTE prevent access
	 *	because we are doing software DIRTY bit management and the
	 *	page is currently not DIRTY. 
	 */


	do {
		old_pte = pte_val(*ptep);
		if (old_pte & _PAGE_BUSY)
			goto out;
		new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
	} while(old_pte != __cmpxchg_u64((unsigned long *)ptep,
					 old_pte, new_pte));

	rflags = 0x2 | (!(new_pte & _PAGE_RW));
 	/* _PAGE_EXEC -> HW_NO_EXEC since it's inverted */
	rflags |= ((new_pte & _PAGE_EXEC) ? 0 : HPTE_R_N);
	if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
		/* No CPU has hugepages but lacks no execute, so we
		 * don't need to worry about that case */
		rflags = hash_huge_page_do_lazy_icache(rflags, __pte(old_pte),
						       trap);

	/* Check if pte already has an hpte (case 2) */
	if (unlikely(old_pte & _PAGE_HASHPTE)) {
		/* There MIGHT be an HPTE for this pte */
		unsigned long hash, slot;

		hash = hpt_hash(va, HPAGE_SHIFT, ssize);
		if (old_pte & _PAGE_F_SECOND)
			hash = ~hash;
		slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
		slot += (old_pte & _PAGE_F_GIX) >> 12;

		if (ppc_md.hpte_updatepp(slot, rflags, va, mmu_huge_psize,
					 ssize, local) == -1)
			old_pte &= ~_PAGE_HPTEFLAGS;
	}

	if (likely(!(old_pte & _PAGE_HASHPTE))) {
		unsigned long hash = hpt_hash(va, HPAGE_SHIFT, ssize);
		unsigned long hpte_group;

		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;

repeat:
		hpte_group = ((hash & htab_hash_mask) *
			      HPTES_PER_GROUP) & ~0x7UL;

		/* clear HPTE slot informations in new PTE */
#ifdef CONFIG_PPC_64K_PAGES
		new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HPTE_SUB0;
#else
		new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HASHPTE;
#endif
		/* Add in WIMG bits */
		rflags |= (new_pte & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
				      _PAGE_COHERENT | _PAGE_GUARDED));

		/* Insert into the hash table, primary slot */
		slot = ppc_md.hpte_insert(hpte_group, va, pa, rflags, 0,
					  mmu_huge_psize, ssize);

		/* Primary is full, try the secondary */
		if (unlikely(slot == -1)) {
			hpte_group = ((~hash & htab_hash_mask) *
				      HPTES_PER_GROUP) & ~0x7UL; 
			slot = ppc_md.hpte_insert(hpte_group, va, pa, rflags,
						  HPTE_V_SECONDARY,
						  mmu_huge_psize, ssize);
			if (slot == -1) {
				if (mftb() & 0x1)
					hpte_group = ((hash & htab_hash_mask) *
						      HPTES_PER_GROUP)&~0x7UL;

				ppc_md.hpte_remove(hpte_group);
				goto repeat;
                        }
		}

		if (unlikely(slot == -2))
			panic("hash_huge_page: pte_insert failed\n");

		new_pte |= (slot << 12) & (_PAGE_F_SECOND | _PAGE_F_GIX);
	}

	/*
	 * No need to use ldarx/stdcx here
	 */
	*ptep = __pte(new_pte & ~_PAGE_BUSY);

	err = 0;

 out:
	return err;
}

void set_huge_psize(int psize)
{
	/* Check that it is a page size supported by the hardware and
	 * that it fits within pagetable limits. */
	if (mmu_psize_defs[psize].shift && mmu_psize_defs[psize].shift < SID_SHIFT &&
		(mmu_psize_defs[psize].shift > MIN_HUGEPTE_SHIFT ||
			mmu_psize_defs[psize].shift == HPAGE_SHIFT_64K)) {
		HPAGE_SHIFT = mmu_psize_defs[psize].shift;
		mmu_huge_psize = psize;
#ifdef CONFIG_PPC_64K_PAGES
		hugepte_shift = (PMD_SHIFT-HPAGE_SHIFT);
#else
		if (HPAGE_SHIFT == HPAGE_SHIFT_64K)
			hugepte_shift = (PMD_SHIFT-HPAGE_SHIFT);
		else
			hugepte_shift = (PUD_SHIFT-HPAGE_SHIFT);
#endif

	} else
		HPAGE_SHIFT = 0;
}

static int __init hugepage_setup_sz(char *str)
{
	unsigned long long size;
	int mmu_psize = -1;
	int shift;

	size = memparse(str, &str);

	shift = __ffs(size);
	switch (shift) {
#ifndef CONFIG_PPC_64K_PAGES
	case HPAGE_SHIFT_64K:
		mmu_psize = MMU_PAGE_64K;
		break;
#endif
	case HPAGE_SHIFT_16M:
		mmu_psize = MMU_PAGE_16M;
		break;
	}

	if (mmu_psize >=0 && mmu_psize_defs[mmu_psize].shift)
		set_huge_psize(mmu_psize);
	else
		printk(KERN_WARNING "Invalid huge page size specified(%llu)\n", size);

	return 1;
}
__setup("hugepagesz=", hugepage_setup_sz);

static void zero_ctor(struct kmem_cache *cache, void *addr)
{
	memset(addr, 0, kmem_cache_size(cache));
}

static int __init hugetlbpage_init(void)
{
	if (!cpu_has_feature(CPU_FTR_16M_PAGE))
		return -ENODEV;

	huge_pgtable_cache = kmem_cache_create("hugepte_cache",
					       HUGEPTE_TABLE_SIZE,
					       HUGEPTE_TABLE_SIZE,
					       0,
					       zero_ctor);
	if (! huge_pgtable_cache)
		panic("hugetlbpage_init(): could not create hugepte cache\n");

	return 0;
}

module_init(hugetlbpage_init);